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  <row Id="1" PostTypeId="1" AcceptedAnswerId="12" CreationDate="2013-12-17T20:23:39.243" Score="43" ViewCount="3907" Body="&lt;p&gt;I recently had the opportunity to fly a PAR approach into Büchel Airbase in Germany. It was a ton of fun and I'll definitely try it again when I get the chance. However, as we were getting set up for the approach I received the following call&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;(callsign)&lt;/em&gt; request heading&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It caught me off guard, and it took a while but I eventually interpreted it as &quot;say heading&quot; and gave him my current heading. He didn't complain, but I'm still not sure if that's what he wanted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A bit later I got a similar call&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;(callsign)&lt;/em&gt; request QNE&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, I was unfamiliar with that &lt;a href=&quot;http://en.wikipedia.org/wiki/Q_code#Aviation&quot;&gt;Q-code&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt; and only later found out it means &quot;pressure altitude&quot;. Q-codes suck. Anyway I said &quot;Say again&quot; and he came back and asked how many were on board (which I incorrectly assumed at that point was what QNE meant), again, using &quot;request&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I've never heard a controller say &quot;request&quot; before, is it just army version of &quot;say&quot;? I'm pretty sure the guy was German, so it might be a German military thing, or a NATO thing, or just a simple mistake on his side?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: As a private pilot in Europe, you pretty much need to know QNH, QFE, QDM and QTE&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="8547" LastEditDate="2015-06-17T10:06:50.987" LastActivityDate="2015-06-17T10:06:50.987" Title="What does it mean when the controller uses the word &quot;request&quot;?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2" PostTypeId="2" ParentId="1" CreationDate="2013-12-17T20:33:20.077" Score="15" Body="&lt;p&gt;&quot;Request &quot; is very common in Europe but it's usually the pilot who will use it to talk to ATC, as in &quot;Request taxi&quot; or &quot;Request to enter your airspace&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never heard this phrase being used by a controller in Belgium, France and The Netherlands (where I've flown the most so far). Seems very odd to me.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="19" LastEditDate="2013-12-17T21:35:25.090" LastActivityDate="2013-12-17T21:35:25.090" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3" PostTypeId="5" CreationDate="2013-12-17T20:38:16.553" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2013-12-17T20:38:16.553" LastActivityDate="2013-12-17T20:38:16.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4" PostTypeId="4" CreationDate="2013-12-17T20:38:16.553" Score="0" Body="Questions regarding air traffic control, the system of controllers assigned the task of managing airspace." OwnerUserId="14" LastEditorUserId="14" LastEditDate="2013-12-22T18:34:25.637" LastActivityDate="2013-12-22T18:34:25.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5" PostTypeId="1" AcceptedAnswerId="8" CreationDate="2013-12-17T20:56:48.547" Score="34" ViewCount="2991" Body="&lt;p&gt;I've never had the opportunity to fly into a controlled airport with parallel runways, so I've never actually faced the situation. But, in the interest of being ahead of it, when would it be prudent to switch to ground frequency with this clearance (assume I just landed)?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N12345, right on E, cross 27 R, contact ground .9&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Should I call ground (or switch frequency, so I no longer hear the tower) before or after crossing 27 R? My by-the-book assumption would be immediately, as there's no &quot;then&quot; or &quot;after crossing&quot; or similar, but somehow that feels wrong. I suppose normally it doesn't really matter, but in the case of someone (which includes me, everyone makes mistakes) doing something wrong, where would they call me as I'm about to cross 27 R?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I ask is that I saw exactly this case in a YouTube video quite a while ago (can't find it anymore though), where exactly this happened. The pilot was narrating for the video and stated he'd switch frequencies &quot;now that he'd crossed the runway&quot;, at which point I started thinking about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the situation, I would probably rather wait since there's an inherent delay when switching frequencies anyway, I might as well wait a bit longer, but knowing myself, if I hadn't thought about it ahead of time I'd probably switch right away. The only reason I can think of for saying it this way is if 27 R is not an active runway, but then again, reality does not always match what's in the book.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="1696" LastEditDate="2015-02-27T21:35:23.183" LastActivityDate="2019-03-06T02:27:14.020" Title="Should you wait to switch to the ground frequency until after crossing a runway?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6" PostTypeId="1" AcceptedAnswerId="13" CreationDate="2013-12-17T21:11:50.633" Score="38" ViewCount="3936" Body="&lt;p&gt;There are some good sights to see inside of class Bravo airspace. What is the best way to plan and communicate to ATC that my intention is to fly into the airspace to see some specific landmarks?&lt;/p&gt;&#xA;" OwnerUserId="26" LastEditorUserId="64" LastEditDate="2014-01-08T06:40:17.550" LastActivityDate="2014-01-17T03:40:08.357" Title="How do I &quot;sightsee&quot; in a class Bravo airspace?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;flight-planning&gt;&lt;class-b-airspace&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7" PostTypeId="1" AcceptedAnswerId="14" CreationDate="2013-12-17T21:12:03.620" Score="36" ViewCount="4055" Body="&lt;p&gt;When I took delivery of a new Cessna 182T last year, I did a test flight for certification purposes. During the test flight we had to perform a power off stall but that didn't go as planned as it was simply impossible to stall. What happened is this: when the airspeed dropped well below the power off stall speed we simply started to sink slowly with a nose-high attitude at about 35 KIAS. This &quot;mushing&quot; went on for what seemed ages before I eventually applied power and pushed the nose down to gain airspeed again. We tried it again after that and the same thing happened. I had an instructor with me who has thousands of hours in a C172 and he had never experienced something like this before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The odd thing is that this only happened during that flight. During later flights this didn't occur anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a passenger in the back seat, fuel tanks only half full so the CG was more aft than usual, but well within limits&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ever since that flight I've wondered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What could cause this to happen? (My guess is it is CG related)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And most importantly:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If I would have continued this &quot;mushing&quot; flight, would it be possible to have entered a flat spin or a simple &quot;drop out of the sky&quot; like the infamous Air France 447?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4" LastEditorUserId="5517" LastEditDate="2015-02-19T20:46:54.023" LastActivityDate="2017-10-18T09:59:02.527" Title="Why would a Cessna 182T not enter a stall?" Tags="&lt;stall&gt;&lt;cg&gt;&lt;single-engine&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8" PostTypeId="2" ParentId="5" CreationDate="2013-12-17T21:12:54.790" Score="30" Body="&lt;p&gt;Remember that active runways are &lt;em&gt;always&lt;/em&gt; the jurisdiction of the local (tower) controller. Even if a ground controller tells you to cross a runway, they have to clear it with the local controller next to them. So generally you switch frequencies when you have finished crossing the runway unless told otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can tell you this is exactly how it works in Boise, Idaho where there are the parallels 10/28 L/R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you are unsure of any instructions a controller gives you, the basic rule is: ask. The tower controller won't mind, and will typically appreciate the clarification. Just read back the crossing instruction as normal, then ask.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Right on E, cross 27 R, contact ground .9, N12345, and should I contact ground on the other side of 27R or immediately?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-17T21:12:54.790" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9" PostTypeId="1" AcceptedAnswerId="11" CreationDate="2013-12-17T21:15:39.547" Score="78" ViewCount="21266" Body="&lt;p&gt;Hypothetical: Let's say (for whatever reason) a pilot became distracted or disorientated, and found themselves in &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspace_class_%28United_States%29#Class_B&quot;&gt;class B airspace&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What steps should they take immediately and after landing to be safe and avoid any backlash from authorities?&lt;/p&gt;&#xA;" OwnerUserId="26" LastEditorUserId="19" LastEditDate="2017-06-06T08:56:03.770" LastActivityDate="2017-06-07T21:24:46.243" Title="I just flew into class B airspace without a clearance, what should I do now?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;airspace&gt;&lt;class-b-airspace&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10" PostTypeId="1" AcceptedAnswerId="17" CreationDate="2013-12-17T21:20:19.807" Score="23" ViewCount="6539" Body="&lt;p&gt;If I only have a private pilot license, and am not the pilot in command, should I log my flight time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what are the limits of this? i.e. is that as true in the backseat as it is in the front seat? Must I have that type rating?&lt;/p&gt;&#xA;" OwnerUserId="26" LastEditorUserId="5517" LastEditDate="2016-07-06T12:23:28.750" LastActivityDate="2020-09-24T18:21:05.907" Title="Should I log flight time as a passenger?" Tags="&lt;logging&gt;" AnswerCount="8" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11" PostTypeId="2" ParentId="9" CreationDate="2013-12-17T21:29:21.003" Score="86" Body="&lt;p&gt;While still in the airspace, you should contact the controller if you can, since it may be important to safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After landing, you may get the dreaded phone number from a controller (probably tower or ground) which you're supposed to call and speak with someone from the FAA. You should not volunteer any information about the incident during this call without talking to a lawyer or AOPA legal services first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, &lt;strong&gt;most importantly&lt;/strong&gt;, fill out a report in the &lt;a href=&quot;http://asrs.arc.nasa.gov/&quot;&gt;Aviation Safety Reporting System&lt;/a&gt;. Any information you submit will not be used against you in an enforcement action by the FAA, and in many cases, people who volunteer information through the system receive much softer treatment, and sometimes forgo enforcement all together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason the FAA incentivizes this self-reporting is so they can better collect information about accidents which inevitably happen. If they know why you accidentally strayed into the bravo, maybe they can improve procedures or charts to help keep other pilots from making the same mistakes.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="3825" LastEditDate="2015-02-19T01:42:56.977" LastActivityDate="2015-02-19T01:42:56.977" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12" PostTypeId="2" ParentId="1" CreationDate="2013-12-17T21:32:49.063" Score="28" Body="&lt;p&gt;In civil aviation the ICAO standard phraseology should be used. This phraseology is described in ICAO document 9432. &#xA;The standard ICAO phraseology is to use the word &lt;em&gt;report&lt;/em&gt; in the first case.&#xA;According to the definitions it means: &quot;Pass me the following information ...&quot;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[callsign] report heading&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The second phrase is even stranger. QNE is the standard pressure altimetry setting of 1013.25 Hectopascal (29.92 inches of mercury in the US). When an altimeter is set to standard pressure, the normal way of reporting the altitude is in Flight Levels. So in this case the standard phraseology should have been&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[callsign] report Flight Level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2013-12-17T21:54:24.113" LastActivityDate="2013-12-17T21:54:24.113" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13" PostTypeId="2" ParentId="6" CreationDate="2013-12-17T21:35:34.120" Score="39" Body="&lt;p&gt;Just call up ATC on the approach frequency and request flight following to see the location you're interested in.  They'll assign you a transponder code and any restrictions.  For example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;N12345:&lt;/strong&gt; &quot;Houston approach, VFR request for Cessna 12345&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Houston TRACON:&lt;/strong&gt; &quot;Cessna 345, say request&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;N12345:&lt;/strong&gt; &quot;Cessna 12345 is at 1200 ft, 3 miles south of Houston Executive, requesting flight following to overfly the Greenway Plaza area for sightseeing, aircraft type is a Charlie 172 slant Golf.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Houston TRACON:&lt;/strong&gt; &quot;Cessna 345, squawk 4123.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;N12345:&lt;/strong&gt; &quot;squawk 4123 for Cessna 345&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Houston TRACON:&lt;/strong&gt; &quot;Cessna 345, radar contact. Cleared into Bravo, maintain at or below 3,500, remain north of the University, advise when your sightseeing is complete.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;N12345:&lt;/strong&gt; &quot;Cessna 345 is cleared into Bravo. Will remain at or below 3,500 and north of the University. Will advise when complete.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notice that it is preferred that you don't give your entire VFR request in the initial callup to avoid overwhelming the controllers if they're busy or not yet prepared to copy your entire request.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just ask for &quot;VFR request&quot; with your callsign and wait for them to ask for the details.&lt;/p&gt;&#xA;" OwnerUserId="27" LastEditorUserId="27" LastEditDate="2014-01-17T03:40:08.357" LastActivityDate="2014-01-17T03:40:08.357" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14" PostTypeId="2" ParentId="7" CreationDate="2013-12-17T21:41:18.467" Score="26" Body="&lt;p&gt;I think this is more common than you might think in a C182. The 182 is much more nose-heavy than a 172 (which is particularly noticeable in the flare) and this seems to limit the amount of upward pitch authority the elevator has at low speeds. The only stalls I've done in a 182 are much as you described - you can hold full back-elevator and you just sort of sit there sinking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinning could be an issue if it becomes uncoordinated, but a 182 is a very stable airplane and unlikely to enter a flat spin unless the CG is beyond the aft limit or severely uncoordinated. Perhaps someone else can weigh in further on that possibility, though.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-17T21:41:18.467" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15" PostTypeId="5" CreationDate="2013-12-17T21:44:12.613" Score="0" Body="&lt;p&gt;In class B airspace, IFR and VFR flights are permitted. All flights are provided with air traffic control services and are separated from each other. ATC clearance is required to operate in Class B airspace. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2013-12-22T18:33:56.463" LastActivityDate="2013-12-22T18:33:56.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16" PostTypeId="4" CreationDate="2013-12-17T21:44:12.613" Score="0" Body="Class B airspace is controlled airspace where both Instrument Flight Rules (IFR) and Visual Flight Rules (VFR) flights are permitted. Air Traffic Control will provide separation services to all flights in class B airspace." OwnerUserId="-1" LastEditorUserId="19" LastEditDate="2015-01-12T19:23:19.243" LastActivityDate="2015-01-12T19:23:19.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17" PostTypeId="2" ParentId="10" CreationDate="2013-12-17T22:07:36.660" Score="35" Body="&lt;p&gt;&lt;strong&gt;No, you &lt;em&gt;should&lt;/em&gt; not*.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, you should limit your logbook to records of your own flight experience. This would include any time spent training, as PIC, or as required crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time you can log as PIC is that which you spend as the &lt;em&gt;sole manipulator of the controls&lt;/em&gt;, the &lt;em&gt;sole occupant&lt;/em&gt;, or &lt;em&gt;as the pilot in command when the required crew is &gt;1&lt;/em&gt;. &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/sdl/local_more/avsafety_program/media/LOGGING%20PILOT-IN-COMMAND%20TIME.pdf&quot;&gt;Here's an article from an FAA FSDO describing the logging of PIC time in more detail&lt;/a&gt;. &lt;a href=&quot;http://www.rodmachado.com/_become_private_pilot/logging_flight_time.php&quot;&gt;Rod Machado&lt;/a&gt; has some good coverage of this as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're just hanging out in the airplane, it doesn't matter if you're in the front seat or the back seat. If you're receiving instruction, you should get an entry and a logbook endorsement from the instructor you're flying with. Most General Aviation aircraft don't require a type rating, so I'm unsure what the context of your final question is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&amp;nbsp;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;* It's worth noting that you can technically put whatever you want in your logbook, though it's not a great idea; when it comes time to fill out an FAA 8710 form for later ratings, it can get confusing. &lt;strong&gt;In my opinion, you still shouldn't log any time&lt;/strong&gt;, but if you're just wanting to record flights that you took with friends, that's fine. As an instructor who's had to slog through some weird logbooks, I'd really, &lt;strong&gt;really&lt;/strong&gt; encourage you to track that elsewhere, though. Your logbook is exactly that - it's &lt;strong&gt;your&lt;/strong&gt; logbook, for the logging of your flight time, and a record of your flight experience and training.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-17T22:34:41.297" LastActivityDate="2013-12-17T22:34:41.297" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18" PostTypeId="1" AcceptedAnswerId="25" CreationDate="2013-12-17T22:15:39.457" Score="17" ViewCount="1723" Body="&lt;p&gt;Let's say you discover that your landing light is inoperable during the preflight. Your aircraft doesn't have a MEL, so you follow 14 CFR §91.213(d). Assuming you do everything else required (placard, etc.), would placing a collar around a circuit breaker be considered deactivation? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, is there anything that a private pilot can do that would be considered deactivation?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="917" LastEditDate="2018-01-14T14:45:18.843" LastActivityDate="2018-01-14T14:45:18.843" Title="Is collaring a circuit breaker considered deactivation by the FAA?" Tags="&lt;faa-regulations&gt;&lt;preflight&gt;&lt;circuit-breaker&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19" PostTypeId="1" AcceptedAnswerId="22" CreationDate="2013-12-17T22:20:36.273" Score="25" ViewCount="2265" Body="&lt;p&gt;If I'm watching an aircraft fly overhead and it becomes apparent to me that it is failing, what action can I take in response to this incident?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For now I will leave this question generic as to location, but if it becomes necessary to narrow it down I am interested in the US specifically.&lt;/p&gt;&#xA;" OwnerUserId="44" LastActivityDate="2019-07-21T09:15:48.923" Title="What can I do as a bystander on the ground if I see an aircraft above me that appears to be failing?" Tags="&lt;aircraft-failure&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20" PostTypeId="5" CreationDate="2013-12-17T22:23:26.933" Score="0" Body="&lt;p&gt;The Federal Aviation Administration is the agency responsible for regulating and administering the United States National Airspace system.  It is a division of the United States Department of Transportation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appropriate questions for this tag would include those activities which require working directly with the FAA, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Certification&lt;/li&gt;&#xA;&lt;li&gt;Approval&lt;/li&gt;&#xA;&lt;li&gt;Letters of Authorization (RVSM, ADS-B, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Company Operations Specification approvals&lt;/li&gt;&#xA;&lt;li&gt;Manual Approvals/Acceptance/Revisions&lt;/li&gt;&#xA;&lt;li&gt;Filling out and submitting various forms (8410, 8710, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Rulemaking Process&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Related Tags&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt; - The United States Federal Aviation Regulations&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/aim&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aim&amp;#39;&quot; rel=&quot;tag&quot;&gt;aim&lt;/a&gt; - The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Information Manual&lt;/a&gt;, published by the FAA.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/usa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;usa&amp;#39;&quot; rel=&quot;tag&quot;&gt;usa&lt;/a&gt; - Questions specific to the United States (but not FAA regulations)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;See Also&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Federal Aviation Administration (&lt;a href=&quot;http://www.faa.gov&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Federal Aviation Administration (&lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Aviation_Administration&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;United States Department of Transportation (&lt;a href=&quot;http://www.dot.gov&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="69" LastEditDate="2014-01-18T16:57:17.527" LastActivityDate="2014-01-18T16:57:17.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21" PostTypeId="4" CreationDate="2013-12-17T22:23:26.933" Score="0" Body="The Federal Aviation Administration is the agency responsible for regulating and administering the United States National Airspace System.  Questions using this tag should **not** be about regulations." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T16:57:17.527" LastActivityDate="2014-01-18T16:57:17.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22" PostTypeId="2" ParentId="19" CreationDate="2013-12-17T22:30:15.063" Score="42" Body="&lt;p&gt;Honestly, very little.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, be clear as to whether you are actually see something failing. If you see flames, or a wing has broken off, then yes, it's a problem. However, if you see someone doing a slow spiral towards an empty field with the power idling, they're more likely to be practicing engine out procedures (something that's required for all US pilots to practice and demonstrate during their checkride for their certificate). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event that you actually see an impact, fire, off-airport landing and so on, call 911 and give them your location. They'll send the appropriate crews. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, if the aircraft is still flying, there's a strong chance the pilot(s) are already talking to ATC about their problem, if it actually exists. There's nothing you really can or need to do in this case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quick Anecdote: I've been told the story of a local police department who gets phone calls virtually every time a citizen lands his small airplane in his private field. Fire/police/medics/etc are summoned, when absolutely nothing bad has happened. This is why you should make an attempt to verify that a problem actually exists before reporting it.&lt;/p&gt;&#xA;" OwnerUserId="50" LastEditorUserId="50" LastEditDate="2013-12-23T09:35:07.073" LastActivityDate="2013-12-23T09:35:07.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23" PostTypeId="5" CreationDate="2013-12-17T22:33:54.653" Score="0" Body="&lt;p&gt;In aviation, standard radio (formally, radiotelephony) phraseology is used to ensure pilots worldwide are able to communicate in an unambiguous manner with Air Traffic Control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most well-known part of standard aviation radio phraseology is the use of the '&lt;a href=&quot;http://en.wikipedia.org/wiki/NATO_phonetic_alphabet&quot; rel=&quot;nofollow noreferrer&quot;&gt;phonetic alphabet&lt;/a&gt;' for letters and numbers: Alpha, Bravo, Charlie etc. This alphabet is not unique to aviation and &lt;a href=&quot;http://en.wikipedia.org/wiki/NATO_phonetic_alphabet#Usage&quot; rel=&quot;nofollow noreferrer&quot;&gt;is used&lt;/a&gt; for other activities where it's important to be able to communicate letters or spell words clearly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO document 9432 (apparently not available online) describes the standard phraseology which forms the basis of aviation radio communications worldwide. The ICAO phraseology is not exhaustive and at local level additional phraseologies can be in use. For example, the FAA issues a &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; that lists all standard words and phrases to be used by pilots and ATC in the US and is broadly aligned with ICAO standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about words, phrases and abbreviations used in aviation radio communications. More general questions about words, phrases or definitions should usually be tagged &lt;a href=&quot;/questions/tagged/terminology&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;terminology&amp;#39;&quot; rel=&quot;tag&quot;&gt;terminology&lt;/a&gt; instead.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Voice_procedure&quot; rel=&quot;nofollow noreferrer&quot;&gt;Voice procedure&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/NATO_phonetic_alphabet&quot; rel=&quot;nofollow noreferrer&quot;&gt;NATO phonetic alphabet&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; (FAA)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="8282" LastEditDate="2018-10-27T21:26:30.597" LastActivityDate="2018-10-27T21:26:30.597" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24" PostTypeId="4" CreationDate="2013-12-17T22:33:54.653" Score="0" Body="Questions about standard words and phrases used by pilots and ATC in radio communications" OwnerUserId="19" LastEditorUserId="62" LastEditDate="2014-11-13T18:36:16.800" LastActivityDate="2014-11-13T18:36:16.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25" PostTypeId="2" ParentId="18" CreationDate="2013-12-17T22:34:06.023" Score="14" Body="&lt;p&gt;Based on &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/13c094a06437c5fa862569d900744d86/%24FILE/Chap1-2.pdf&quot;&gt;this Advisory Circular&lt;/a&gt;, the answer is yes.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;g. Deactivation means to make a piece of equipment or an instrument unusable to the pilot/crew by preventing its operation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Collaring the circuit breaker prevents it from being pushed in, and therefore prevents its operation.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-17T22:34:06.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26" PostTypeId="2" ParentId="5" CreationDate="2013-12-17T22:54:42.733" Score="1" Body="&lt;p&gt;You have been cleared by the tower to cross a runway so you should stay with the tower frequency until you've crossed it. The reason being that ground control is not authorized to issue clearances for runway crossings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;In theory&lt;/em&gt;&lt;/strong&gt;, you should never cross a runway when on ground frequency because the tower is in charge of that.&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2013-12-17T22:54:42.733" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27" PostTypeId="1" AcceptedAnswerId="35" CreationDate="2013-12-17T22:58:51.143" Score="13" ViewCount="495" Body="&lt;p&gt;Consider a hypothetical pilot who knows they have a medical condition which the FAA considers disqualifying (under the standard medical qualification standards). Is that pilot permitted to operate under sport-pilot privileges if they do not believe their condition interferes with their ability to safely perform their sport piloting duties? Must that pilot consult with a private physician? If so, must the physician offer some sort of approval?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a &lt;a href=&quot;http://www.faa.gov/licenses_certificates/medical_certification/sportpilots/response4/&quot; rel=&quot;noreferrer&quot;&gt;similar question&lt;/a&gt; on the FAQ, but doesn't seem to answer it fully. They &quot;suggest&quot; consultation with a physician. Does that suggestion indicate a pilot who does not do so is in violation of a FAR?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;edit: This question is concerning operation of a powered airplane.&lt;/p&gt;&#xA;" OwnerUserId="48" LastEditorUserId="3201" LastEditDate="2015-12-31T09:44:36.100" LastActivityDate="2015-12-31T09:44:36.100" Title="What are the FAA sport-pilot self-certification standards?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28" PostTypeId="1" AcceptedAnswerId="31" CreationDate="2013-12-17T22:59:58.970" Score="23" ViewCount="11202" Body="&lt;p&gt;What are the minimum requirements for obtaining a privates pilot certificate if a pilot  already has a sport pilot certificate? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirements for a private pilot certificate don't changes because you already have a sport pilot license. However by successfully obtaining a Sport Pilot certificate, you should have already completed some of the private pilot requirements.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How much of your sport pilot training counts towards your private&#xA;pilot license?   &lt;/li&gt;&#xA;&lt;li&gt;How much of the training will have to be re-done?&lt;/li&gt;&#xA;&lt;li&gt;Does it depend on&#xA;the type of your flight instructor's certificate?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="51" LastEditorUserId="7532" LastEditDate="2015-12-31T19:42:21.100" LastActivityDate="2020-05-13T04:46:40.987" Title="What does a sport pilot have to do to get a private pilot certificate in the US?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;pilot-certification&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29" PostTypeId="1" AcceptedAnswerId="178" CreationDate="2013-12-17T23:19:06.760" Score="16" ViewCount="813" Body="&lt;p&gt;I'm interested in short, or trick, take-offs - such as from platforms, tall trees, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that I should have &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a &lt;a href=&quot;http://www.onsetcomp.com/products/sensors/s-wca-m003&quot;&gt;wind speed and direction&lt;/a&gt; measure&lt;/li&gt;&#xA;&lt;li&gt;an understanding of my wing surface area&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This will let me add to my intuition from regular launches (from sites with known-good launch conditions), and estimate how much velocity I need to add via a run / push.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The methodology to count the wind measure seem a bit more &lt;em&gt;grey&lt;/em&gt;, right now.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can have a sense of the wind where I am, but it may quickly change beyond my launch site.  Since I'm considering how to launch from a stationary position, it would be good to feed my senses / calculations more data like this.&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="39" LastEditDate="2013-12-19T06:41:02.677" LastActivityDate="2018-09-14T16:53:50.507" Title="How can I estimate the minimum runway needed to take off with a hang glider?" Tags="&lt;glider&gt;&lt;unpowered&gt;&lt;measurement&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="31" PostTypeId="2" ParentId="28" CreationDate="2013-12-18T00:24:18.830" Score="16" Body="&lt;p&gt;If you hold a Sport Pilot certificate and are looking to upgrade it to a Private Pilot certificate, your best bet is to use the requirements of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.5&quot;&gt;Part 61 Subpart E&lt;/a&gt;. All of the flight time you logged earning a Sport Pilot certificate applies towards Private, but additional hours and types of flight time need to be logged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirements for each are paraphrased below. You'd have to log the difference, which is a minimum of &lt;strong&gt;20 hours&lt;/strong&gt;, including another 5 hours of dual and 5 hours of solo. There's a lot more to it than what I reference below, but this is the basics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;How much of the training will have to be re-done?&lt;/em&gt; This should vary wildly from pilot to pilot. You'll need to redo training as required to meet standards. If you're transitioning right away, theoretically none, but it's likely that some retraining will be required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Does it depend on the type of your flight instructor's certificate?&lt;/em&gt; Yes.  If the instructor has only a sport pilot instructor certificate, none of the dual instruction hours are able to be counted for the private pilot dual hours criteria.  They are not an &quot;authorized instructor&quot; for private pilot privileges.  If the CFI had a CFI-airplane certificate then those dual hours working towards the sport pilot certificate will count toward the dual hour requirements of the private pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/kern%20ink%20-%20(2009)%20legal%20interpretation.pdf&quot;&gt;Kern INK Interpretation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Required for Sport&lt;/strong&gt; (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.10.1.7&quot;&gt;citation&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;20 hours of flight time, including at least: &#xA;15 hours of flight training from an authorized instructor and at least:&#xA;5 hours of solo flight training in the areas of operation listed in §61.311&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Required for Private&lt;/strong&gt; (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.5.1.5&quot;&gt;citation&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;40 hours of flight time that includes at least:&#xA;20 hours of flight training from an authorized instructor and: &#xA;10 hours of solo flight training in the areas of operation listed in §61.107(b)(1)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;If you've chosen a flight school that operates a Part 141 program, you get to do it all over. Hooray!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="9491" LastEditDate="2015-11-21T12:24:00.930" LastActivityDate="2015-11-21T12:24:00.930" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="32" PostTypeId="1" AcceptedAnswerId="33" CreationDate="2013-12-18T00:41:42.787" Score="17" ViewCount="3394" Body="&lt;p&gt;I've got schools with both part approvals in my area. I'm just interested in recreational flying, I'm not sure which part is more suited to my needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the differences I should consider before choosing one or the other?&lt;/p&gt;&#xA;" OwnerUserId="13" LastEditorUserId="3201" LastEditDate="2015-12-31T09:40:01.270" LastActivityDate="2015-12-31T09:40:01.270" Title="What's the difference between FAA Part 61 and Part 141 training?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="33" PostTypeId="2" ParentId="32" CreationDate="2013-12-18T00:47:58.653" Score="9" Body="&lt;p&gt;There's no singular right answer, it's up to the individual and how he or she learns best. The biggest difference between the two you'll find is that part 141 schools are always very structured in their training regiment. That is not to say part 61 isn't (nor does it imply that it's better for everyone), it's just that part 61 does things according to what they wish with less FAA oversight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might know that under part 141, the earliest you can get your ticket is 35 hours, while part 61 requires a minimum of 40 hours. Don't let that red herring influence you; almost everyone takes more than 40 hours regardless of the school type.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2013-12-18T00:47:58.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="35" PostTypeId="2" ParentId="27" CreationDate="2013-12-18T01:10:53.877" Score="10" Body="&lt;p&gt;Unless the pilot has had their certificate revoked or suspended by the FAA for their medical condition or has failed an application for a medical certificate&lt;sup&gt;1&lt;/sup&gt;, they would probably be fine after seeing a physician. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=886855e9ac707a9a56fa07aa2c588d8b&amp;amp;node=14:2.0.1.1.2.1.1.17&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;FAR 61.23(c)(2)&lt;/a&gt; states that sport pilots using a driver's license to satisfy medical requirements must:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(ii) Have been found eligible for the issuance of at least a third-class airman medical certificate at the time of his or her most recent application (if the person has applied for a medical certificate);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Not have had his or her most recently issued medical certificate (if the person has held a medical certificate) suspended or revoked or most recent Authorization for a Special Issuance of a Medical Certificate withdrawn; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) Not know or have reason to know of any medical condition that would make that person unable to operate a light-sport aircraft in a safe manner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the holder has a valid US driver's license, it would (presumably) be taken upon the certificate holder to have &quot;reason to know&quot; by virtue of having a checkup with a physician to check that this condition does not affect their ability to fly safely, especially if the person involved was in any sort of doubt as to their medical condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if they have had a checkup with a physician that finds no particular issues, and that condition does not affect the validity of their driver's license, they should be fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sup&gt;1: &lt;/sup&gt;By section (ii), the pilot must still have a medical test and pass for at least a Class 3 medical certificate, if the FAA has revoked or found unsatisfactory their previous medical under a Class 1 or Class 2 certificate.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2013-12-18T05:51:03.120" LastActivityDate="2013-12-18T05:51:03.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="37" PostTypeId="1" AcceptedAnswerId="38" CreationDate="2013-12-18T01:25:20.083" Score="13" ViewCount="650" Body="&lt;p&gt;I'm from Brazil, and here we use the West/East rule, so we use an odd flight level when we fly between &lt;code&gt;0/360 - 179&lt;/code&gt;, and when we fly between &lt;code&gt;180 - 359&lt;/code&gt; we fly in an even flight level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what should you do in other countries? Where I can find those rules?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard that in Europe it's totally different, and that in some countries in Asia they use meters, instead of feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where can I find this information?&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="1696" LastEditDate="2015-04-16T16:14:05.600" LastActivityDate="2015-04-16T16:14:05.600" Title="Where can I find regulations in different countries for flight level rules based on direction of flight?" Tags="&lt;flight-planning&gt;&lt;regulations&gt;&lt;flight-level&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="38" PostTypeId="2" ParentId="37" CreationDate="2013-12-18T01:34:56.767" Score="13" Body="&lt;p&gt;Every country's Civil Aviation Authority issues an Aeronautical Information Publication (AIP) as part of their Aeronautical Information Services (AIS) which contains the information you are looking for. Most likely the information about Flight Level rules will be contained in the GEN (General) or ENR (En-Route) section. For Europe, most information from the AIP's can be found through the &lt;a href=&quot;http://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&quot;&gt;European AIS Database&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2013-12-18T01:34:56.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="39" PostTypeId="1" AcceptedAnswerId="596" CreationDate="2013-12-18T01:54:12.867" Score="14" ViewCount="3695" Body="&lt;p&gt;If a pilot holding a US certificate wanted to convert it to an equivalent EASA (JAA?) certificate, what training, flight experience, and exams are necessary to obtain equivalency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the process differ for private, instrument, commercial, ATP, and instructor ratings?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2014-01-18T17:13:30.617" LastActivityDate="2014-01-18T17:13:30.617" Title="What are the requirements to convert an FAA certificate to EASA/JAA?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;easa-regulations&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="40" PostTypeId="1" AcceptedAnswerId="260" CreationDate="2013-12-18T02:08:23.297" Score="12" ViewCount="2641" Body="&lt;p&gt;What types of factors come into account when planning takeoff performance for dual engine aircraft under FAR 23, compared to the aircraft with certified takeoff distances under FAR 25 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the margin for light aircraft would be less, but does this difference make a significant change in the required (legal) distance or is it less that it seems?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-04-16T23:55:48.740" Title="How do FAR 23 takeoff requirements compare to FAR 25 requirements?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="41" PostTypeId="1" AcceptedAnswerId="49" CreationDate="2013-12-18T02:49:47.420" Score="32" ViewCount="7879" Body="&lt;p&gt;The Boeing 757 (at least in the US) is in a special class of its own with respect to air traffic control wake turbulence advisories and separation. This is apparently due to it producing stronger wake vortices than would be expected from an aircraft of similar size and weight. What about the 757's design causes these strong vortices? What led to the decision to treat it differently than similar aircraft?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="97" LastEditDate="2014-01-13T02:13:49.723" LastActivityDate="2016-05-21T20:57:16.393" Title="What is the cause of unusually strong wake turbulence from the 757?" Tags="&lt;air-traffic-control&gt;&lt;aerodynamics&gt;&lt;boeing&gt;&lt;wake-turbulence&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="42" PostTypeId="1" AcceptedAnswerId="94" CreationDate="2013-12-18T03:02:08.533" Score="8" ViewCount="1455" Body="&lt;p&gt;My electronic E6B does calculations for both planned and actual true airspeed (yielding different results). I was told the difference has to do with assumptions about temperature, but the manual doesn't give any details. What is the difference between the two?&lt;/p&gt;&#xA;" OwnerUserId="79" LastActivityDate="2013-12-18T17:29:25.673" Title="What is the difference between planned true airspeed and actual true airspeed?" Tags="&lt;e6b&gt;&lt;temperature&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="43" PostTypeId="1" AcceptedAnswerId="86" CreationDate="2013-12-18T03:08:04.773" Score="12" ViewCount="546" Body="&lt;p&gt;Here in Idaho we have a lot of mountains and desert areas where if I had to make an emergency landing or crashed it may take a very long time to find me. In that case I can see the benefit to opening a flight plan. But in areas where I'm flying over most or all populated areas, someone would see the crash well before they would start looking for me. In that case, are there other reasons to file and open a flight plan?&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2020-06-27T16:07:15.613" Title="Are there benefits to opening a flight plan if I'm flying over populated areas?" Tags="&lt;safety&gt;&lt;flight-planning&gt;&lt;fss&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="44" PostTypeId="1" AcceptedAnswerId="46" CreationDate="2013-12-18T03:09:47.847" Score="13" ViewCount="13370" Body="&lt;p&gt;Automated airport weather observations can be produced by several types of equipment: AWOS-A, AWOS-1, AWOS-2, AWOS-3, and ASOS are the ones I've seen mentioned. What are the differences between these reporting systems? Are the older systems still prevalent, or have they been mostly converted to the new systems?&lt;/p&gt;&#xA;" OwnerUserId="79" LastActivityDate="2016-12-29T17:56:22.667" Title="What is the difference between the various automated airport weather observing systems?" Tags="&lt;weather&gt;&lt;asos&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="46" PostTypeId="2" ParentId="44" CreationDate="2013-12-18T03:28:29.533" Score="6" Body="&lt;p&gt;ASOS is basically a replacement for AWOS with more reporting parameters, and the first units were installed in 1991.  According to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Automated_airport_weather_station&quot; rel=&quot;noreferrer&quot;&gt;Automated airport weather station Wikipedia page&lt;/a&gt;, each different type has the following parameters:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;AWOS&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;AWOS A: barometric pressure and altimeter setting (in inches of    Mercury). &lt;/li&gt;&#xA;  &lt;li&gt;AWOS I: wind speed and wind gusts (in knots), wind    direction (from which the wind is blowing) and variable wind    direction (in&#xA;  degrees of the compass), temperature and dew point (in    degrees&#xA;  Celsius), altimeter setting and density altitude. &lt;/li&gt;&#xA;  &lt;li&gt;AWOS II:    all AWOS I parameters, plus visibility and variable visibility (in    miles). &lt;/li&gt;&#xA;  &lt;li&gt;AWOS III: all AWOS II parameters, plus sky condition (in    oktas), cloud ceiling height (in feet), and liquid precipitation&lt;br&gt;&#xA;  accumulation (in inches). &lt;/li&gt;&#xA;  &lt;li&gt;AWOS III P: all AWOS III parameters, plus    precipitation type (rain, snow and sometimes drizzle) identification.&lt;/li&gt;&#xA;  &lt;li&gt;AWOS III T: all AWOS III parameters, plus thunderstorm detection (via    a cloud-to-ground lightning detector). &lt;/li&gt;&#xA;  &lt;li&gt;AWOS III P/T: all AWOS III    parameters, plus precipitation type identification and thunderstorm    detection. &lt;/li&gt;&#xA;  &lt;li&gt;AWOS IV Z: all AWOS III P/T parameters, plus freezing rain    detection via a freezing rain sensor (Note: this configuration used&lt;br&gt;&#xA;  to be called AWOS III PTZ). &lt;/li&gt;&#xA;  &lt;li&gt;AWOS IV R: all AWOS III P/T parameters,    plus runway surface condition. &lt;/li&gt;&#xA;  &lt;li&gt;AWOS IV Z/R: all AWOS III P/T    parameters, plus freezing rain detection and runway surface    condition.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ASOS&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;They generally report all the parameters of the AWOS-III, while also&#xA;  having the additional capabilities of reporting temperature and dew&#xA;  point in degrees Fahrenheit, present weather, icing, lightning, sea&#xA;  level pressure and precipitation accumulation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-18T03:28:29.533" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="47" PostTypeId="1" AcceptedAnswerId="71" CreationDate="2013-12-18T03:45:52.563" Score="7" ViewCount="3306" Body="&lt;p&gt;From what I understand, whether or not a flight is classified as private or commercial in the eyes of US Customs and Border Protection (CBP) has nothing to do with the Federal Aviation Regulations (FAR) flight rules that they are operating under. For instance, I understand that I can legally be operating under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR Part 91&lt;/a&gt; and still be a commercial flight in the eyes of CBP. What then is the determining factor?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="12247" LastEditDate="2020-01-22T07:35:19.523" LastActivityDate="2020-01-22T07:35:19.523" Title="What is the difference between a private and a commercial flight according to the US Customs and Border Protection?" Tags="&lt;us-cbp&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="48" PostTypeId="2" ParentId="42" CreationDate="2013-12-18T04:01:44.387" Score="2" Body="&lt;p&gt;It's very possible that your flight computer's TAS calculation is expecting calibrated airspeed rather than indicated airspeed; the difference between these two can often be enough to affect your results by a meaningful amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft do not have a formula for the conversion, or enough information to convert airspeeds other than those specified in the manual. This means that the &quot;CAS&quot; used for TAS calculations is often actually IAS. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-18T16:28:29.447" LastActivityDate="2013-12-18T16:28:29.447" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="49" PostTypeId="2" ParentId="41" CreationDate="2013-12-18T04:12:24.283" Score="30" Body="&lt;p&gt;My understanding, primarily based on &lt;a href=&quot;http://web.archive.org/web/20090731181404/http://oea.larc.nasa.gov/PAIS/Concept2Reality/wake_vortex.html&quot;&gt;this archived NASA document&lt;/a&gt; (also linked to on the B757 Wikipedia article), is that there were several issues leading to the decision to make the 757 a special case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First&lt;/strong&gt;, there were some notable accidents where witnesses seemed to indicate the cause was 757 wake turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cessna Citation - December 18, 1992 - Billings, Montana&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Witnesses reported that the airplane suddenly and rapidly rolled left and then contacted the ground while in a near-vertical dive. Recorded ATC radar data showed that, at the point of upset, the Citation was about 2.8 nmi behind a Boeing 757 and on a flight path that was about 300 ft below the flight path of the 757.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;IAI Westwind - December 15, 1993 - Santa Ana, California&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;witnesses reported that the airplane rolled abruptly and that the onset of the event was sudden. The Westwind was about 2.1 nmi behind a Boeing 757 and on a flight path that was about 400 ft below the flight path of the 757.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Additional accidents were noted with a Cessna 182, MD-88, and a Boeing 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second&lt;/strong&gt;, there were some controversial NOAA flyby tests which showed:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;for a peculiar set of weather conditions that lasted about 0.5 hour, the vortex velocity of the 757 was approximately 50 percent higher than that of the 767 at similar vortex ages (younger than 60 sec) measured in less favorable weather conditions. However, the results also showed that overall the wake of the 757 decayed faster than that of the 767; in fact, the wake behaved as would be expected for an aircraft of the size and weight of the 757.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third&lt;/strong&gt;, they felt the slower approach speed of the 757 (vs. similar aircraft) made it more likely that trailing aircraft would inadvertently close the separation gap during approach.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ultimately, I believe the correct answer to your question is actually that there is nothing particularly special about the B757 in regards to wake turbulence. This &lt;a href=&quot;http://www.airspacemag.com/need-to-know/Need_To_Know_757_hazard.html?c=y&amp;amp;page=2&quot;&gt;Air&amp;amp;Space Magazine Article&lt;/a&gt; indicates that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boeing maintains that there is nothing about the wing design that would cause wake turbulence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The wake from the 757 is no stronger or weaker than you would predict from the weight, span, and speed of the airplane,&quot; agrees NASA's David Hinton, who has taken wake measurements at airports around the country and is principal investigator of NASA's NextGen Airportal Project.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The decision to put the 757 in its own category was controversial at the time and not based on particularly strong evidence. It was done out of precaution due to anecdotal evidence and possibly flawed test results. On the other hand, you could argue that ATC erring on the side of caution is best if there is any doubt. To be fair, a 757 is on the &lt;em&gt;larger&lt;/em&gt; side of the small category.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2013-12-18T05:32:43.870" LastActivityDate="2013-12-18T05:32:43.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="50" PostTypeId="2" ParentId="43" CreationDate="2013-12-18T04:13:53.683" Score="5" Body="&lt;p&gt;The biggest thing that comes to mind is that even if somebody saw your aircraft crash (or land off airport), they may not know to respond, or who to contact. A flight plan has aircraft and pilot info attached, including emergency contact. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure that the assumption that somebody will see the crash is quite right, but it's certainly more likely than in the backcountry!&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-18T04:13:53.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="51" PostTypeId="1" AcceptedAnswerId="58" CreationDate="2013-12-18T04:48:30.490" Score="39" ViewCount="3954" Body="&lt;p&gt;Just what the title states.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the Wright brothers, aviation technology for fixed-wing craft has advanced by an order or more. Rotary wing craft on the other hand (I know little about aviation; please correct me!) have advanced significantly by way of lift capacity, and maneuverability. Yet velocity has achieved nothing like the kind of advance seen in case of fixed-wing craft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is a rotary wing craft capable of supersonic flight? &lt;/li&gt;&#xA;&lt;li&gt;How is it limited by contemporary technology?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="83" LastEditorUserId="39" LastEditDate="2014-01-07T05:24:20.653" LastActivityDate="2014-03-07T20:37:39.050" Title="Is a rotary wing craft capable of supersonic flight?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;&lt;supersonic&gt;&lt;rotary-wing&gt;&lt;theory&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="52" PostTypeId="2" ParentId="32" CreationDate="2013-12-18T04:54:26.600" Score="7" Body="&lt;p&gt;I did my training at a Part 61 school, but we followed Jeppesen's Part 141 syllabus. So the differences can be minimal if choose that route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not relevant to Private Pilot training, but an important difference between Part 61 and Part 141, when it comes to Instrument training, is that Part 61 requires 50 hours of PIC cross-country, whereas Part 141 does not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I wanted to start my instrument rating, I only had 25 hours PIC cross-country, so Part 141 sounded appealing to me. Having recently moved to New York City and not knowing anyone in aviation here, I called the owner of a Part 141 school, and immediately disliked him. He was arrogant and egotistical and didn't care about anything I had to say. He just wanted to brag about his airline experience and how organized his school is... then didn't even call me back at the time he said he would. So I called up another flight school and immediately liked them and went flying with them the same week. Unfortunately they're only a Part 61 school, but the fact that I like them is a big win.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point is, the biggest difference between any two schools is not actually 61 vs. 141, it's the people who run it, and whether or not you mesh with them. Unless you have commercial ambitions (where Part 141 might help get you where you're going faster), base your decision on the &lt;em&gt;people&lt;/em&gt;, not the &lt;em&gt;part&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-18T04:54:26.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="53" PostTypeId="1" CreationDate="2013-12-18T05:03:43.213" Score="15" ViewCount="2009" Body="&lt;p&gt;I understand that you need to get an overflight permit before entering Cuban airspace, even if you aren't landing there.  How do you go about getting permission to overfly them enroute to another country?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Updated now that flights to Cuba are allowed by US operators.  What has changed, and what are the requirements now?  Can we pay them directly yet?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-08-16T02:15:53.067" LastActivityDate="2018-08-04T02:38:29.780" Title="What is required to fly over Cuba enroute to another country?" Tags="&lt;us-cuba&gt;&lt;iacc&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="54" PostTypeId="1" AcceptedAnswerId="99" CreationDate="2013-12-18T05:15:18.933" Score="11" ViewCount="132" Body="&lt;p&gt;Because of US foreign policy, flights between the US and Cuba are prohibited except for certain conditions.  If I am flying there for an approved reason (such as to visit immediate family), how do I obtain the proper permission to do so?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-18T19:01:05.263" Title="How does a US registered pilot obtain approval to fly to Cuba?" Tags="&lt;us-cbp&gt;&lt;us-cuba&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="55" PostTypeId="1" CreationDate="2013-12-18T05:19:59.677" Score="6" ViewCount="891" Body="&lt;p&gt;I have heard conflicting information regarding pre-clearing customs in the USVI.  On one hand, I have heard that once you clear customs you are done and don't need to do anything special on arrival.  But the I've also heard that you need to land at an Airport of Entry upon arrival and notify local customs of your arrival.  I have even called Customs and Border Protection and gotten conflicting answers!  What is actually required?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-04-09T19:54:21.000" Title="What are the US Customs requirements upon returning to the US after pre-clearing customs in the US Virgin Islands?" Tags="&lt;us-cbp&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="56" PostTypeId="2" ParentId="5" CreationDate="2013-12-18T05:50:46.460" Score="12" Body="&lt;pre&gt;&lt;code&gt;N12345, right on E, cross 27 R, contact ground .9&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Do it in exactly the order they tell you. Right turn on E, cross the next runway, then stop and contact ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have an airport diagram handy if you can, it will make a world of difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ETA: If they want you to switch to ground before crossing 27R, they'll probably just say this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;N12345, right on E, contact ground .9&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;In which case, you turn right on E, cross the hold position lines, stop, and switch to ground. The ground controllers will direct you the rest of the way, coordinating with tower controllers where crossing runways is required. In fact, in this case, they'll probably give you very explicit instructions not to cross any more runways until told to do so.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="87" LastEditDate="2013-12-28T17:10:53.333" LastActivityDate="2013-12-28T17:10:53.333" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="57" PostTypeId="1" AcceptedAnswerId="73" CreationDate="2013-12-18T05:53:44.753" Score="16" ViewCount="7044" Body="&lt;p&gt;I have heard about Simultaneous Offset Instrument Approaches (SOIA), special procedures for runways that are spaced particularly close together. How exactly do they work? What are the requirements for an airport to be eligible for the procedure? What special requirements are there for pilots flying the approach?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="72" LastEditDate="2014-03-03T05:24:46.800" LastActivityDate="2019-06-10T23:13:17.843" Title="What is a Simultaneous Offset Instrument Approach (SOIA)?" Tags="&lt;iaps&gt;&lt;runways&gt;&lt;approach&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="58" PostTypeId="2" ParentId="51" CreationDate="2013-12-18T05:59:46.707" Score="36" Body="&lt;p&gt;Currently there is no rotary wing craft capable of supersonic flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combined with the forward motion through the air, the rotating blades attack the air on one side and retreat backwards on the other.  As the aircraft moves faster this poses 2 problems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The retreating blade has a point of zero air speed, starting from the axis at hover and moving to the tip with forward speed, an effect known as &lt;strong&gt;&lt;a href=&quot;http://www.av8n.com/how/htm/yaw.html#sec-p-factor&quot;&gt;P-factor&lt;/a&gt;&lt;/strong&gt;.  Eventually a large portion of the blade has negative airflow (backwards to what it had when hovering) causing loss of lift control on that side (there may still be lift, but the pitch of the blade has little influence). The craft will roll (and I believe gyro forces will bring the pitch up, and the craft will recover)&lt;/li&gt;&#xA;&lt;li&gt;The advancing blade will go supersonic, starting from the tip. Aerodynamics change.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are ideas of new blade actuators that can change the blade for 1) reverse airspeed and 2) supersonic aerodynamics.  As you have noticed, nothing has panned out so far...&lt;/p&gt;&#xA;" OwnerUserId="85" LastEditorUserId="85" LastEditDate="2013-12-24T04:44:36.270" LastActivityDate="2013-12-24T04:44:36.270" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="59" PostTypeId="2" ParentId="9" CreationDate="2013-12-18T06:06:22.207" Score="52" Body="&lt;p&gt;I've done it three times in 1200 hours of flying, I must admit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First time, my plane was performing better than usual (conditions were just right) and I nicked the SFO airspace on climb-out. About 20 minutes later, they called me with a phone number to call when I landed. Spent the rest of the flight shitting bricks. When I got to my destination, I was chewed out by the controller for about fifteen minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was so rattled I didn't leave my home airport again until I'd gone up with an instructor for a refresher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second time was in Boston. I flew through an airspace extension that wasn't on the map. Spent a few minutes on the radio arguing with the controller about it. &quot;It's not on my map&quot;. &quot;Well, we have a letter of agreement with the local airports.&quot; &quot;But it's not on my map, how was I supposed to know?&quot;. Nothing else ever came of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lesson learned: the space between the top of a class D and the bottom of the overlying class B airspace might be considered part of the class B, so just avoid them unless you're under ATC control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third time, I was in contact with ATC, skirting outside the lowest layer of their class B. I turned left to avoid a cloud when I should have turned right, and got chewed out by the controller and told to make an immediate right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, the bottom line is that if you didn't actually endanger anybody, and just nicked the corner of the airspace (which is what I did in all three cases), you'll probably just get away with a stern talking-to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But blunder through the path of an incoming airliner, and you're probably looking at a 4-month suspension of your license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Filing an &lt;a href=&quot;http://asrs.arc.nasa.gov/report/electronic.html&quot;&gt;ASRS report&lt;/a&gt; is probably a very good idea if it ever happens to you.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="87" LastEditDate="2014-04-27T14:24:42.267" LastActivityDate="2014-04-27T14:24:42.267" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="60" PostTypeId="1" AcceptedAnswerId="62" CreationDate="2013-12-18T06:13:48.507" Score="36" ViewCount="76965" Body="&lt;p&gt;Wind information can be reported by various sources (ATIS, METAR, TAF, spoken on the radio, etc). I was taught that officially some of these sources are relative to magnetic north and others to true north (although practically this isn't always followed). Which sources are supposed to use which reference system?&lt;/p&gt;&#xA;" OwnerUserId="79" LastActivityDate="2017-04-06T04:00:49.723" Title="When are winds given with respect to true vs. magnetic north?" Tags="&lt;wind&gt;&lt;magnetic-variation&gt;&lt;metar&gt;&lt;atis&gt;&lt;radio-communications&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="61" PostTypeId="2" ParentId="10" CreationDate="2013-12-18T06:15:19.537" Score="4" Body="&lt;p&gt;Adding to what egid said, you can only log flight time as a crew member if you're filling a role as a &lt;em&gt;required&lt;/em&gt; crew member.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was an enforcement action many years ago against a pilot who was flying right seat in a small cargo plane because his employer's rules required two people in the cockpit. He figured that since his employer required him to be there, it made him a required crew member and so he logged the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the FAA regs did &lt;em&gt;not&lt;/em&gt; require him to be there, so in their view, he was &lt;em&gt;not&lt;/em&gt; a required crew member and they took action against him for falsifying his logs.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="100" LastEditDate="2013-12-18T18:55:35.810" LastActivityDate="2013-12-18T18:55:35.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="62" PostTypeId="2" ParentId="60" CreationDate="2013-12-18T07:05:30.327" Score="40" Body="&lt;p&gt;The general rule is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If you read it, it's true. If you hear it, it's magnetic.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All charts and textual sources (METAR, TAF, winds aloft, surface analysis charts, etc) use true north as the reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATIS/AWOS/ASOS broadcasts, or any information a controller gives you over the radio, is magnetic.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wind direction broadcast over FAA radios is in reference to magnetic north.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM Section 7-1-11&lt;/a&gt; (page 7-1-26 in the 5/26/16 edition)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One exception to the &quot;if you hear it&quot; rule is that a FSS briefer will read you the winds referenced to true north, since they're just reading you the charts/textual information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is at least true in the United States... other countries may vary in some instances)&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2017-04-06T04:00:49.723" LastActivityDate="2017-04-06T04:00:49.723" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="63" PostTypeId="1" AcceptedAnswerId="229" CreationDate="2013-12-18T08:45:13.627" Score="26" ViewCount="4945" Body="&lt;p&gt;Suppose you're the co-pilot on a flight and during pre-flight, talking to the captain, you smell alcohol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although you didn't see him drinking and the smell isn't strong, what does regulation stipulate you should do?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-22T02:33:44.577" LastActivityDate="2014-03-22T02:33:44.577" Title="What to do if the captain smells like alcohol?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;pilots&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="64" PostTypeId="1" AcceptedAnswerId="102" CreationDate="2013-12-18T09:10:31.267" Score="45" ViewCount="161344" Body="&lt;p&gt;During taxi, the taxi lights are used, and I think the landing lights are required to be used up to 10.000 feet for all commercial flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, my question is regarding the abovementioned lights: beacon, anti-collision, strobe, logo, and navigation lights. When are they to be used, and when should they not be used? What is the meaning and purpose of each one?&lt;/p&gt;&#xA;" OwnerUserId="70" LastEditorUserId="22726" LastEditDate="2019-02-22T04:16:35.323" LastActivityDate="2019-06-14T20:14:04.780" Title="When to use beacon, anti-collision, strobe, logo, and navigation lights?" Tags="&lt;faa-regulations&gt;&lt;aircraft-lighting&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="65" PostTypeId="1" AcceptedAnswerId="84" CreationDate="2013-12-18T09:12:04.723" Score="52" ViewCount="101059" Body="&lt;p&gt;I'm not a professional pilot, just an enthusiast, so this might seem obvious to others; but I noticed that airports don't use sequential numbering for runways, starting from 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Liverpool (for example) has runway 9/27; so how are these numbers assigned? Also, what do Left and Right signify?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2020-11-03T09:34:29.973" Title="How are runways numbered?" Tags="&lt;runways&gt;&lt;airport&gt;" AnswerCount="6" CommentCount="10" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="66" PostTypeId="2" ParentId="65" CreationDate="2013-12-18T09:12:04.723" Score="14" Body="&lt;p&gt;Runway numbers are determined by their heading, e.g. for Liverpool, runway 9/27 is facing approx. &lt;a href=&quot;https://aviation.stackexchange.com/questions/82/whats-the-difference-between-true-vs-magnetic-headings&quot;&gt;magnetic heading&lt;/a&gt; 90° in one direction, and 270° in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airport has parallel runways, these would then be marked Left, Center and Right, e.g. 9L/9C/9R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heathrow has two parallel runways, the 'right' runway has &lt;a href=&quot;https://goo.gl/maps/qJ5JA&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;09 R&lt;/strong&gt;&lt;/a&gt; on the east and &lt;a href=&quot;https://goo.gl/maps/l1kD8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;27 L&lt;/strong&gt;&lt;/a&gt; on the west end (and the other is 09L/27R).&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="1467" LastEditDate="2017-08-18T10:08:29.457" LastActivityDate="2017-08-18T10:08:29.457" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="67" PostTypeId="1" AcceptedAnswerId="144" CreationDate="2013-12-18T09:37:19.057" Score="13" ViewCount="1539" Body="&lt;p&gt;I obtained a JAR PPL in 2003 and flew regularly for a few years afterwards. My last flight as Pilot in Command was around 2006 and as I have not kept up the required number of hours per year since then I'm assuming my license will have lapsed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do I need to do to regain my PPL? Will I need to retake the exams, the radio telephony license, and the Skills Test?&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2016-09-08T10:20:40.467" LastActivityDate="2016-09-08T10:20:40.467" Title="How do I renew/revalidate my lapsed JAR PPL?" Tags="&lt;pilot-certification&gt;&lt;easa&gt;&lt;ppl&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="68" PostTypeId="1" AcceptedAnswerId="212" CreationDate="2013-12-18T09:40:49.780" Score="10" ViewCount="1454" Body="&lt;p&gt;I've found a 737 &lt;a href=&quot;http://www.pulsaraviation.com/techdata/737%20Maintenance%20Planning%20Data%20D6-38278%20Rev94%2025Mar2011/01___031.pdf&quot;&gt;maintenance planning data document&lt;/a&gt; produced by Boeing, which gives a suggested schedule on page 6.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also found a British Airways &lt;a href=&quot;http://media.corporate-ir.net/media_files/irol/69/69499/bafactbook/2007/Section3_March2007.pdf&quot;&gt;Fact Book document&lt;/a&gt;, which on the last page gives a schedule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So who decides how often an aircraft and its individual components should be inspected? Is it the manufacturer, the airline, or somebody else? Is there a set standard or does this differ between manufacturers/airlines/countries?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2018-07-03T13:57:43.953" Title="Who decides an aircraft's maintenance schedule?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="69" PostTypeId="1" AcceptedAnswerId="469" CreationDate="2013-12-18T09:56:30.090" Score="10" ViewCount="11429" Body="&lt;p&gt;I used to work for a company making maintenance software for the shipping industry. Each component, from a cylinder in an engine to the furnace has to be inspected after (e.g.) 10,000 running hours, or every 2 years, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Are task cards like the one below still used in aviation, or is there a more up-to-date way of working nowadays? (The PDF I got this from is 10,000 pages long)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What must airlines do to ensure their planes are maintained according to schedule?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mViou.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2013-12-18T16:43:16.840" LastActivityDate="2019-09-13T17:45:23.803" Title="Are task cards still used in aircraft maintenance?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="70" PostTypeId="1" CreationDate="2013-12-18T10:33:48.477" Score="16" ViewCount="701" Body="&lt;p&gt;Does anyone have data on how much time the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-225_Mriya&quot; rel=&quot;noreferrer&quot;&gt;An-225&lt;/a&gt; (only one was produced; it is currently the largest aircraft in the world) spends flying/on missions and how much it waits for customers?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a very unique aircraft within the scope of contemporary aviation:&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SeBDE.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there is a copy of the plane - partially built.  Does that suggest there might be need for the completion of second aircraft, to meet demand?&lt;/p&gt;&#xA;" OwnerUserId="105" LastEditorUserId="22726" LastEditDate="2019-05-18T21:54:33.330" LastActivityDate="2019-05-18T21:54:33.330" Title="What is the usage ratio of the An-225 Mriya?" Tags="&lt;commercial-operations&gt;&lt;cargo&gt;&lt;antonov-225&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="71" PostTypeId="2" ParentId="47" CreationDate="2013-12-18T11:59:03.750" Score="8" Body="&lt;p&gt;According to the &lt;a href=&quot;https://eapis.cbp.dhs.gov/docs/help.html#a2&quot; rel=&quot;nofollow&quot;&gt;CBP eAPIS FAQ&lt;/a&gt;, this definition is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a329147dbf8d2fc6eb123e0adf6aeed8&amp;amp;mc=true&amp;amp;node=se19.1.122_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;19 CFR 122.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) &lt;em&gt;Commercial aircraft&lt;/em&gt;. A “commercial aircraft” is any aircraft&#xA;  transporting passengers and/or cargo for some payment or other&#xA;  consideration, including money or services rendered.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) &lt;em&gt;Private aircraft&lt;/em&gt;. A “private aircraft” is any aircraft engaged in&#xA;  a personal or business flight to or from the U.S. which is not:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Carrying passengers and/or cargo for commercial purposes;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Leaving the U.S. carrying neither passengers nor cargo in order to&#xA;  lade passengers and/or cargo in a foreign area for commercial&#xA;  purposes; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Returning to the U.S. carrying neither passengers nor cargo in&#xA;  ballast after leaving with passengers and/or cargo for commercial&#xA;  purposes;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-12-14T17:37:58.513" LastActivityDate="2015-12-14T17:37:58.513" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="72" PostTypeId="2" ParentId="53" CreationDate="2013-12-18T12:18:25.957" Score="3" Body="&lt;p&gt;AOPA has a &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/May/23/Cuba-makes-changes-to-overflight-permit-fees.aspx&quot; rel=&quot;nofollow&quot;&gt;short article&lt;/a&gt; about flying over Cuba, it includes the following quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is important for all U.S. pilots and U.S. aircraft owners to know&#xA;  that in order to request a[n overflight] permit, or to pay fees to Cuba related to&#xA;  your aircraft, you must obtain an OFAC license or retain the services&#xA;  of a provider that has an OFAC license&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since OFAC appears to have &lt;a href=&quot;http://www.treasury.gov/about/organizational-structure/offices/Pages/Office-of-Foreign-Assets-Control.aspx&quot; rel=&quot;nofollow&quot;&gt;virtually no web presence&lt;/a&gt;, I would assume that using a third-party provider is the most viable option. Another (older) AOPA &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2009/May/6/Air-Journey-plans-trips-to-Cuba.aspx&quot; rel=&quot;nofollow&quot;&gt;article&lt;/a&gt; mentions one.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-18T12:18:25.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="73" PostTypeId="2" ParentId="57" CreationDate="2013-12-18T12:40:55.300" Score="23" Body="&lt;p&gt;SOIA (Simultaneous Offset Instrument Approaches) allow airports with parallel runways that are 750 to 3000 feet apart to conduct (almost) simultaneous approaches to the two runways. At an airport, one runway uses the ILS PRM approach, while the other runway uses an offset LDA PRM approach (with glideslope). SOIA refers to the LDA PRM approach, where another aircraft is flying the ILS PRM approach ahead. PRM stands for Precision Runway Monitor, which is a high-update radar system allowing for &quot;equivalent&quot; safety with reduced margins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a PRM approach is conducted, there must be two frequencies per runway:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a primary frequency for both the transmission and receipt of instructions&lt;/li&gt;&#xA;&lt;li&gt;a &quot;monitor&quot; frequency, only for ATC to transmit on&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The reason for the &quot;monitor&quot; frequency is just in case the primary frequency is blocked and breakout instructions have to be provided. The tower controller will communicate to aircraft on both frequencies, both in normal PRM operations and when providing breakout instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a &quot;monitor&quot; controller that ensures that the two aircraft never get dangerously close together -- if such a situation occurs, the &quot;monitor&quot; controller overrides the tower controller on both frequencies to allow for immediate breakout instructions to be given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of the two approaches, the more interesting of the two is the offset LDA PRM approach. In the LDA PRM approach, aircraft fly an approach course that is 2.5 to 3 degrees offset from the runway heading, following the glideslope until the MAP (this course does not meet up with the runway threshold), at which point the pilot should proceed visually to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html#B$8Kqe6atcn&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CwXJv.png&quot; alt=&quot;Diagram of an LDA PRM approach (SOIA) -- FAA AIM&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MAP on a LDA PRM approach is 3000 feet away from the ILS approach course, meaning aircraft have to manoeuvre towards the extended runway centreline to be stable by 500 feet -- the less spacing between the two runways, the more aircraft will have to turn. This does mean that it is less suitable to larger aircraft, due to the manoeuvring required at higher speeds (than other aircraft), though most SOIA approaches are designed for larger aircraft as well. Before reaching the MAP, the pilot must have have:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the runway in sight;&lt;/li&gt;&#xA;&lt;li&gt;the aircraft on the adjacent ILS PRM approach in sight; and&lt;/li&gt;&#xA;&lt;li&gt;notified ATC that traffic is in sight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This means that the aircraft on the ILS PRM approach should be ahead of the other aircraft. To allow time for visual contact, aircraft should be clear of cloud before the MAP, which is taken into account when deciding on the minimum cloud ceiling allowed for the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NTZ (No Transgression Zone) is a 2000 foot wide area between the two approach courses which aircraft must not enter at any time. ATC would immediately issue breakout instructions to both aircraft if an aircraft breaches the NTZ, as there would be very little horizontal separation between the two aircraft. [The FAA AIM][3] states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the unlikely event that an aircraft &quot;blunders&quot; off its course and makes a worst case turn of 30 degrees toward the adjacent final approach course, closing speeds of 135 feet per second could occur that constitute the need for quick reaction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Special training requirements vary from country to country. In the US, SOIA special training requirements are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Parts 121/129/135: operator training as agreed to by FAA and educational video&lt;/li&gt;&#xA;&lt;li&gt;Part 91 transport category: read about PRM approaches in AIM, video&lt;/li&gt;&#xA;&lt;li&gt;Part 91 other: read about PRM and SOIA approaches in AIM, video&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An example of a SOIA approach is the SFO runway 28R LDA PRM approach:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZsMn6.png&quot; alt=&quot;KSFO LDA PRM RWY 28R&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="8282" LastEditDate="2019-06-10T23:13:17.843" LastActivityDate="2019-06-10T23:13:17.843" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="74" PostTypeId="2" ParentId="65" CreationDate="2013-12-18T12:48:35.940" Score="12" Body="&lt;p&gt;The information from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0203.html&quot; rel=&quot;noreferrer&quot;&gt;US AIM&lt;/a&gt; may be useful here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. Runway Designators. Runway numbers and letters are determined from&#xA;  the approach direction. The runway number is the whole number nearest&#xA;  one‐tenth the magnetic azimuth of the centerline of the runway,&#xA;  measured clockwise from the magnetic north. The letters, differentiate&#xA;  between left (L), right (R), or center (C), parallel runways, as&#xA;  applicable:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. For two parallel runways “L” “R.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. For three parallel runways “L” “C” “R.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As to why the runway is actually constructed on heading 1, 9 or something else, that is determined by the local prevailing wind conditions among other considerations (terrain etc.). Aircraft always take off or land into the wind (as far as possible), so that is a key factor in how runways are positioned. NASA has a very good &lt;a href=&quot;http://virtualskies.arc.nasa.gov/airport_design/5.html&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt; on airport layouts that goes into more detail.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-08-14T17:14:38.857" LastActivityDate="2014-08-14T17:14:38.857" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="75" PostTypeId="5" CreationDate="2013-12-18T15:05:37.087" Score="0" Body="&lt;p&gt;Question regarding transport of goods using aircraft.&lt;/p&gt;&#xA;" OwnerUserId="105" LastEditorUserId="105" LastEditDate="2013-12-22T18:35:59.473" LastActivityDate="2013-12-22T18:35:59.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="76" PostTypeId="4" CreationDate="2013-12-18T15:05:37.087" Score="0" Body="Question regarding transport of goods using aircraft." OwnerUserId="105" LastEditorUserId="105" LastEditDate="2013-12-22T18:33:04.737" LastActivityDate="2013-12-22T18:33:04.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="77" PostTypeId="1" AcceptedAnswerId="105" CreationDate="2013-12-18T15:06:38.823" Score="29" ViewCount="4453" Body="&lt;p&gt;It's easy to go online and look at prices of a Cessna 172, but what are some examples &lt;strong&gt;&lt;em&gt;of how to break down&lt;/em&gt;&lt;/strong&gt; the real world costs of ownership? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How much other maintenance should you plan for?&lt;/li&gt;&#xA;&lt;li&gt;How much does an engine overhaul cost?&lt;/li&gt;&#xA;&lt;li&gt;Insurance&lt;/li&gt;&#xA;&lt;li&gt;Hangar&lt;/li&gt;&#xA;&lt;li&gt;etc..&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It would be great to also get some typical costs and ranges, since some element are more predictable than others.  Obviously the costs will vary based on individual aircraft and location, as well as over time, but I'm looking for information that would help someone make the buy/rent decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking for &lt;em&gt;the structure of the costs&lt;/em&gt; to start making a plan for cost analysis and diligence. For example, with an IFR aircraft, what costs are involved with keeping it current?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="1696" LastEditDate="2015-10-07T14:59:12.140" LastActivityDate="2015-10-13T23:13:07.733" Title="What are the typical facets of ownership costs, for a single engine aircraft?" Tags="&lt;aircraft-maintenance&gt;&lt;cost&gt;&lt;aircraft-ownership&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="78" PostTypeId="1" AcceptedAnswerId="81" CreationDate="2013-12-18T15:43:49.210" Score="23" ViewCount="3063" Body="&lt;p&gt;I did my initial training in a high altitude area, where it got pretty hot in the summer,  so I'm not at all surprised when I hear an ASOS announce:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Caution: Density Altitude (a few thousand above field elev.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But recently, I was flying in SE. Kansas when it was extremely cold outside. The ASOS announced:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Caution: Density Altitude minus 1800 ft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I understand that cold winter air can make the air extremely dense, leading to a negative density altitude. But I don't understand the &lt;strong&gt;caution&lt;/strong&gt; part of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I'm aware, low density altitudes mean your engine generates more power, and your wings generate more lift. Everything is better with low density altitudes, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the &lt;strong&gt;caution&lt;/strong&gt; for?  What should I be looking out for?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="1696" LastEditDate="2016-06-14T16:52:51.943" LastActivityDate="2016-06-14T16:52:51.943" Title="Why would ASOS have a caution for Low Density Altitude?" Tags="&lt;weather&gt;&lt;density-altitude&gt;&lt;asos&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="79" PostTypeId="2" ParentId="78" CreationDate="2013-12-18T16:01:05.230" Score="8" Body="&lt;p&gt;The &lt;strong&gt;caution&lt;/strong&gt; is probably the default prefix for a nonstandard DA notice, not anything particular to the fact that it's negative. You're correct that lower DA will improve performance, and an &lt;a href=&quot;https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56396/FAA%20P-8740-02%20DensityAltitude%5Bhi-res%5D%20branded.pdf&quot;&gt;FAAsafety.gov document on density altitude (PDF)&lt;/a&gt; doesn't discuss low DA at all.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-18T16:01:05.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="81" PostTypeId="2" ParentId="78" CreationDate="2013-12-18T16:13:40.157" Score="20" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Low density altitudes mean your engine generates more power, and your wings generate more lift. Everything is better with low density altitudes, right?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The potential danger in low density altitudes is that your engine generates more power than it can handle. Even without exceeding the maximum rated RPM and manifold pressure, you can exceed the rated power of an engine under low density altitude conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low temperatures the air becomes denser. At standard sea level conditions air has a temperature of 15 degrees Celcius and a density of 1.225 kg per cubic meter. &#xA;When the temperature is -30 degrees Celcius, the density increases to 1.452 kg per cubic meter. The equivalent altitude where this density is found under standard atmosphere conditions would be about -5900 ft. This is called the density altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When air with these properties enters the combustion chamber of your engine and is combusted to the normal exhaust temperature it expands (increases in pressure) far more that air normally would, resulting in excessive power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.faasafety.gov/gslac/alc/libview_normal.aspx?id=10520&quot;&gt;FAA paper on Winter Flying Tips&lt;/a&gt; says the following about the risks associated with low density altitudes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do not overboost supercharged engines. This is easy to do because at very low density altitude, the engine &quot;thinks&quot; it is operating as much as 8,000 feet below sea level in certain situations. Care should be exercised in operating normally aspirated engines. Power output increases at about 1% for each ten degrees of temperature below that of standard air. At -40 degree F, an engine will develop 10 percent more than rated power even though RPM and MP limits are not exceeded. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2013-12-19T15:07:45.763" LastActivityDate="2013-12-19T15:07:45.763" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="82" PostTypeId="1" AcceptedAnswerId="83" CreationDate="2013-12-18T16:19:49.553" Score="27" ViewCount="128764" Body="&lt;p&gt;What is the difference between a true and a magnetic heading?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are/were magnetic headings used in aviation?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-17T06:09:42.497" LastActivityDate="2021-02-15T21:50:20.183" Title="What's the difference between True vs Magnetic headings?" Tags="&lt;flight-instruments&gt;&lt;navigation&gt;&lt;magnetic-variation&gt;&lt;heading&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="83" PostTypeId="2" ParentId="82" CreationDate="2013-12-18T16:30:01.190" Score="17" Body="&lt;p&gt;The &quot;heading&quot; refers to the direction an aircraft is pointing. For a Magnetic Heading, this is in relation to Magnetic North. For a True Heading, this is in relation to True North.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;True North&lt;/strong&gt; is directly over the earth's axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Magnetic North&lt;/strong&gt; is somewhere over Canada, moving towards Russia.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To get the &lt;strong&gt;Magnetic Heading&lt;/strong&gt;, you just read it off the magnetic compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get the &lt;strong&gt;True Heading&lt;/strong&gt;, you need to first read the magnetic compass, then either add an Easterly, or subtract a Westerly, magnetic variation; based upon the isogonic lines on your sectional (the purple dashed lines labeled 5°W, 3°E, etc).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example 1: Magnetic Heading 177 w/ 3 degrees East Magnetic deviation = true course 180. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example 2: Magnetic Heading 177 w/ 3 degrees West Magnetic deviation = true course 174. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Because of this, in the past, magnetic headings were used because a simple compass could be used. Finding reliable true headings was difficult until the era of things like the gyrocompass (patented in 1906 (Germany) and 1908 (USA)) and more recently, GPS.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-05-14T18:15:19.550" LastActivityDate="2017-05-14T18:15:19.550" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="84" PostTypeId="2" ParentId="65" CreationDate="2013-12-18T16:30:51.977" Score="61" Body="&lt;p&gt;Runways are usually numbered according to their direction, more precisely called runway magnetic bearing or QFU (&lt;a href=&quot;http://en.wikipedia.org/wiki/Q_code&quot;&gt;see Q codes&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a plane flying toward the runway on final approach in a day without any wind. Divide its magnetic heading by 10, round it to the nearest whole number and you'll usually get the runway number. For example, if the magnetic heading is 345° then 345/10=34,5, so the runway number will be 35 which will be a runway used for landings (and takeoffs) to the north.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Opposite ends of the same runway have different numbers, 18 (which represents 180 degrees) apart. A runway with 35  for landings to the north will have runway 17 for landings to the south. Even though these are the same strip of concrete, they are treated as separate runways by pilots and controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there are two airports near one another with runways at the same angle, sometimes one of the airports will add or subtract one from the runway number to help planes differentiate between the airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Occasionally a runway number will change when the magnetic declination angle changes in such amount, making the runway magnetic bearing divided by 10 and rounded to the nearest whole number increase or decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some runways in areas of large magnetic declination use true instead of magnetic headings for the runway numbers. This is not unusual in northern Canada and Greenland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is more than one parallel runway at an airport, L, R, or C may be appended to the runway number for Left, Right, or Center. These are based on the approach direction, so, for example, the runway 35L would be called 17R from the opposite direction.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="854" LastEditDate="2014-08-15T12:48:36.200" LastActivityDate="2014-08-15T12:48:36.200" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="85" PostTypeId="2" ParentId="64" CreationDate="2013-12-18T16:41:02.463" Score="22" Body="&lt;p&gt;Here are some types of lights: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A &lt;strong&gt;beacon&lt;/strong&gt; is a light that flashes slowly. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Strobes&lt;/strong&gt; are the bright white lights that flash about once per second.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Navigation lights&lt;/strong&gt; are the red, green, and white lights that are on continuously, like on a boat. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Logo lights&lt;/strong&gt; are lights used to light up something on the side of the plane, and their use is optional.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Strobes and beacons are considered anti-collision lights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anti-collision lights, if the plane has them, should be used whenever the engine is running except when they interfere with ground operations. Strobes do not have to be used all the time if a beacon is on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigation lights should be used during night operations.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-19T17:26:00.620" LastActivityDate="2013-12-19T17:26:00.620" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="86" PostTypeId="2" ParentId="43" CreationDate="2013-12-18T16:42:58.920" Score="11" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0501.html&quot;&gt;AIM section 5-1-4&lt;/a&gt;, the main reason is search and rescue:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. It is strongly recommended that a flight plan (for a VFR flight) be&#xA;  filed with an FAA FSS. This will ensure that you receive VFR Search&#xA;  and Rescue Protection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the question becomes, does search and rescue have value in populated areas? I would say that - excluding large cities - populated areas are actually not very densely populated at all (relatively speaking), and there is a very good chance that no one will see your aircraft come down or even react if they do. You might be flying at night, or no one may be looking in the right direction, or they may assume you're landing at a private strip or doing cropdusting or whatever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And even when an aircraft is known to be down in a specific area, it's often very hard to find it - especially if you land in trees - so anything you can do to narrow down the search area is important. An AOPA safety video (I forget which one) mentioned an incident where a helicopter went down less than a mile from a runway threshold at a class B airport and it still took 24 hours to locate it (the details may be different, but you get the idea).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-18T16:42:58.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="87" PostTypeId="1" AcceptedAnswerId="91" CreationDate="2013-12-18T16:43:07.407" Score="18" ViewCount="1760" Body="&lt;p&gt;When ATC gives you headings to fly, do they consider wind correction? In theory they should because they call it a &lt;strong&gt;&lt;em&gt;heading&lt;/em&gt;&lt;/strong&gt; and not a &lt;strong&gt;&lt;em&gt;track&lt;/em&gt;&lt;/strong&gt;, but do they? After all, the heading they want you to fly depends on wind direction and airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or do they actually mean &lt;strong&gt;&lt;em&gt;track&lt;/em&gt;&lt;/strong&gt; instead of &lt;strong&gt;&lt;em&gt;heading&lt;/em&gt;&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="69" LastEditDate="2013-12-27T01:36:11.850" LastActivityDate="2013-12-27T01:36:11.850" Title="Do controllers take wind into account when giving headings?" Tags="&lt;air-traffic-control&gt;&lt;heading&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="88" PostTypeId="2" ParentId="63" CreationDate="2013-12-18T16:48:17.597" Score="-1" Body="&lt;p&gt;This is clear cut. You are required to wait 8 hours after taking a drink of alcohol before you fly a plane. According to FAA regulations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may act or attempt to act as a crewmember of a civil&#xA;  aircraft—&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) Within 8 hours after the consumption of any alcoholic beverage;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) While under the influence of alcohol;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(3) While using any drug that affects the person's faculties in any&#xA;    way contrary to safety; or&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(4) While having an alcohol concentration of 0.04 or greater in a&#xA;    blood or breath specimen. Alcohol concentration means grams of alcohol&#xA;    per deciliter of blood or grams of alcohol per 210 liters of breath.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;(b) Except in an emergency, no pilot of a civil aircraft may allow a&#xA;  person who appears to be intoxicated or who demonstrates by manner or&#xA;  physical indications that the individual is under the influence of&#xA;  drugs (except a medical patient under proper care) to be carried in&#xA;  that aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) A crewmember shall do the following:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) On request of a law enforcement officer, submit to a test to&#xA;    indicate the alcohol concentration in the blood or breath, when—&lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(i) The law enforcement officer is authorized under State or local law&#xA;      to conduct the test or to have the test conducted; and&lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;(ii) The law enforcement officer is requesting submission to the test&#xA;      to investigate a suspected violation of State or local law governing&#xA;      the same or substantially similar conduct prohibited by paragraph&#xA;      (a)(1), (a)(2), or (a)(4) of this section.&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="110" LastEditorUserId="39" LastEditDate="2014-01-03T20:09:39.287" LastActivityDate="2014-01-03T20:09:39.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="89" PostTypeId="2" ParentId="55" CreationDate="2013-12-18T16:54:02.123" Score="1" Body="&lt;p&gt;You're required to notify and clear customs if you land in the 50 U.S. states or Puerto Rico from the U.S. Virgin Islands, even though the U.S. Virgin Islands is part of the U.S.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;All private aircraft arriving in the United States via the Gulf of Mexico or the Atlantic&#xA;Coast from a foreign location in the Western Hemisphere south of 30 degrees north&#xA;latitude, or from any place in Mexico or from the U.S. Virgin Islands, shall also furnish a&#xA;notice of intended arrival. Such aircraft must then land for inspection at the nearest&#xA;designated airport unless an overflight exemption has been granted under Section&#xA;122.25 of the Customs Regulations.&quot;&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-18T16:54:02.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="90" PostTypeId="2" ParentId="7" CreationDate="2013-12-18T17:00:19.043" Score="6" Body="&lt;p&gt;A stall occurs based on angle of attack, not speed. If the plane tends to nose over near stall speed, the angle of attack may not increase enough for a full stall, even though the plane is losing altitude. If you want to perform a low speed stall in the plane, keep pulling the stick back to maintain altitude or climb slightly as the power is eased off. Use the rudder to keep the wings level to reduce the likelihood of a spin.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-18T17:00:19.043" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="91" PostTypeId="2" ParentId="87" CreationDate="2013-12-18T17:01:01.077" Score="13" Body="&lt;p&gt;When the controller says &lt;strong&gt;heading&lt;/strong&gt;, he means &lt;strong&gt;heading&lt;/strong&gt;. &#xA;So if he wants you to go into a specific direction, he will take wind into account. The reason for issuing heading are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Every aircraft can fly it, because a compass is fitted on every aircraft. Track keeping requires more sophisticated avionics. &lt;/li&gt;&#xA;&lt;li&gt;If two aircraft fly adjacent to each other, the wind will offset them by the same amount and therefore separation is assured. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Quite often a controller will ask you to report your present heading prior to instructing a one so he can make more accurate adjustments to your course, especially if you were under own navigation before being vectored. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With Mode S radars and the right equipment in the aircraft, the current heading can be downloaded from the avionics without the pilot being aware of it. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2013-12-18T17:11:35.837" LastActivityDate="2013-12-18T17:11:35.837" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="92" PostTypeId="2" ParentId="87" CreationDate="2013-12-18T17:19:02.453" Score="8" Body="&lt;p&gt;ATC gives headings, and they mean &lt;strong&gt;heading&lt;/strong&gt;; any wind correction is included in the controller's planning. You'll occasionally hear controllers adjust headings (&quot;turn 10 degrees left&quot;) because the wind exceeded their expectations. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-18T17:19:02.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="93" PostTypeId="1" AcceptedAnswerId="95" CreationDate="2013-12-18T17:28:04.207" Score="21" ViewCount="1859" Body="&lt;p&gt;What is the best way to keep logbook entries backed up?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should a photocopied or scanned image on a computer suffice? Can an Excel spreadsheet or other software/apps be used? In case a logbook is lost or (unfortunately) destroyed, should all entries from the backup be rewritten in a new logbook?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when one has 100s or 1000s of hours, spreading over several logbooks, how much importance the older logbooks will have? Would someone go over every page to make sure that this individual actually have 1375.2 hours (as an example)?&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="5517" LastEditDate="2015-02-19T20:42:21.213" LastActivityDate="2015-02-19T20:42:21.213" Title="What is the best way to keep logbook entries backed up?" Tags="&lt;logging&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="94" PostTypeId="2" ParentId="42" CreationDate="2013-12-18T17:29:25.673" Score="2" Body="&lt;p&gt;From the manual for &lt;a href=&quot;http://www.sportys.com/source/slashpages/manuals/E6B%20manual_new.pdf&quot; rel=&quot;nofollow&quot;&gt;an electronic E6B&lt;/a&gt; which seems to be similar to yours:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PLANNED TRUE AIRSPEED&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This function is used to calculate true airspeed for preflight &#xA;  planning. It will compute the true airspeed in knots and Mach  number&#xA;  and density altitude, given the pressure altitude,  temperature, and&#xA;  calibrated airspeed in knots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ACTUAL TRUE AIRSPEED &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This function calculates true airspeed, Mach number and  density&#xA;  altitude given pressure altitude, indicated temperature  in Celsius&#xA;  and calibrated airspeed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The manual doesn't give any more information on the difference between the two calculations so we can only guess...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both methods use pressure altitude and calibrated airspeed. One clue is that the &quot;planned&quot; version uses &quot;temperature&quot;, while the &quot;actual&quot; version uses &quot;indicated temperature&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my guess is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you use the &quot;actual&quot; version in flight, and it expects you to input &lt;a href=&quot;http://en.wikipedia.org/wiki/Total_air_temperature&quot; rel=&quot;nofollow&quot;&gt;Total Air Temperature&lt;/a&gt; (TAT), read from the gauge in the airplane, which it then converts to Outside Air Temperature (OAT) to do the density altitude and true airspeed calculation. &lt;/li&gt;&#xA;&lt;li&gt;You use the &quot;planned&quot; version for flight planning, where the temperature you have available is the OAT.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The TAT is the OAT plus the rise in temperature due to the air being brought to rest relative to the airplane. &#xA;Since the TAT is a bit higher than the OAT, the &quot;actual&quot; version should give slightly lower density altitude and a slightly lower true airspeed.&lt;/p&gt;&#xA;" OwnerUserId="16" LastActivityDate="2013-12-18T17:29:25.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="95" PostTypeId="2" ParentId="93" CreationDate="2013-12-18T17:43:42.800" Score="14" Body="&lt;p&gt;The FAA requirements are for the information to be logged, without specifying the details of how it is logged. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's OK to use electronic log books, and multiple log books. Scanned images are as good as photocopies. Just print them if you ever need them on paper. Some items are required to be signed, so scanned signatures and endorsements may be necessary in an electronic logbook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The older the information, the less its importance. Log books are normally examined to see if what you're doing is legal, checking ratings, currency, training and reviews, etc. If you are flying without required night or IFR currency, for example, it is conceivable that they'd want to check previous flights to see how often that has happened in the past. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An insurance company might want to make sure you've got the hours you claim, but the FAA's interest is to see if you are legal.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-18T17:43:42.800" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="96" PostTypeId="1" AcceptedAnswerId="98" CreationDate="2013-12-18T18:08:23.557" Score="36" ViewCount="14697" Body="&lt;p&gt;I've been watching a lot of videos shot with mini cameras (like a GoPro) from outside the aircraft. Some look like they're mounted on or under wings, others from underneath the aircraft. This looks cool, I want to do it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the FAA is pretty strict on unapproved modifications to aircraft and I've heard that attaching cameras can conflict with this. What should I know before I attempt to attach a camera to the outside of my aircraft?&lt;/p&gt;&#xA;" OwnerUserId="13" LastEditorUserId="19" LastEditDate="2015-06-19T08:57:50.583" LastActivityDate="2015-06-19T08:57:50.583" Title="Can I attach a camera to the outside of my aircraft in the USA?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="98" PostTypeId="2" ParentId="96" CreationDate="2013-12-18T18:46:21.560" Score="27" Body="&lt;p&gt;The NTSB actually &lt;a href=&quot;http://www.ntsb.gov/doclib/recletters/2012/A-12-048-049.pdf&quot;&gt;recommended&lt;/a&gt; the use of exterior cameras to the FAA in 2012.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to be &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=35049&quot;&gt;something of&lt;/a&gt; a &lt;a href=&quot;http://www.askacfi.com/5681/mounting-camera-on-outside-of-aircraft.htm&quot;&gt;grey area&lt;/a&gt;, but it looks like you should contact your local FSDO for approval of an &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/field_approvals/field_approv_proc/&quot;&gt;external load&lt;/a&gt; if you're permanently fixing a camera to a plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The grey area comes in that if the camera is temporarily attached, you shouldn't need special approval, but in practicality it could come loose and damage the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GoPro says this about affixing their cameras to planes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Industrial strength suction cup. Strong enough to pull dents out of a car door or stay attached to an airplane at 200mph+, proven though not endorsed by GoPro per FAA rules.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's a &lt;a href=&quot;http://www.supercub.org/forum/showthread.php?43970-GoPro-2-External-Camera-Mount-Minor-Alteration/page2&quot;&gt;forum thread&lt;/a&gt; where someone asked the FSDO to sign it off as a Minor Alteration, and it was determined that a short logbook entry would suffice:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Temporarily installed a GoPro camera mounted to a standard inspection panel on (Left/Right) lower wing in place of the standard inspection panel. There are no electrical connections associated with this installation. This is a minor alteration as it has no appreciable effect on performance, flight characteristics, or other qualities affecting airworthiness (refer to FAR 1.1 Major Alteration and FAR 21.93). A net weight change of 9 oz is incurred with the temporary installation; therefore, the weight and balance change is negligible (refer to AC 43.13 1B, 10-2 (c)).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2013-12-18T19:10:20.340" LastActivityDate="2013-12-18T19:10:20.340" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="99" PostTypeId="2" ParentId="54" CreationDate="2013-12-18T19:01:05.263" Score="3" Body="&lt;p&gt;To obtain approval to fly to Cuba you must first sumbit an application for an OFAC (Office of Foreign Assets Control) License through their &lt;a href=&quot;https://licensing.ofac.treas.gov/Apply/Introduction.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cuba Travel&lt;/a&gt; website or by mail:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Office of Foreign Assets Control&lt;/p&gt;&#xA;&lt;p&gt;U.S. Department of the Treasury&lt;/p&gt;&#xA;&lt;p&gt;Treasury Annex&lt;/p&gt;&#xA;&lt;p&gt;1500 Pennsylvania Avenue, NW&lt;/p&gt;&#xA;&lt;p&gt;Washington, DC 20220&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Once you have your OFAC license, that completes your US legal requirements, as far as I'm aware.* There are other requirements that you have to fulfill to receive a Cuban visa upon entering, but since you have asked about obtaining US approval I haven't looked into that in detail.&lt;/p&gt;&#xA;&lt;p&gt;For the record, this is the same method that anyone would use to travel to Cuba. Pilots flying to Cuba must ensure that all their passengers also have their own individual OFAC license.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;* &lt;em&gt;I am not a lawyer. Please do not consider this to be legal advice. I would recommend calling OFAC and inquiring for further help with the process.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Sources:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.treasury.gov/resource-center/sanctions/Programs/Documents/cuba.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cuba: What You Need To Know About U.S. Sanctions Against Cuba - OFAC&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.treasury.gov/about/organizational-structure/offices/Pages/Office-of-Foreign-Assets-Control.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;OFAC Contact Info&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="44" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2013-12-18T19:01:05.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="100" PostTypeId="1" AcceptedAnswerId="116" CreationDate="2013-12-18T19:01:55.480" Score="13" ViewCount="1804" Body="&lt;p&gt;Flight hours costs approximately $285 per hour. Below is a screenshot from a local (Newport Beach, CA) school regarding what it takes to become a private pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hB327.png&quot; alt=&quot;local costs&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I was hoping that maybe there might be a school in a local country like Mexico where I could do that for less money. If so, are there any things that I need to take into consideration. Or how do I make sure that those hours will be applicable to my license to be able to fly in the US?&lt;/p&gt;&#xA;" OwnerUserId="117" LastEditorUserId="97" LastEditDate="2014-01-13T02:10:32.453" LastActivityDate="2019-04-12T19:26:11.533" Title="Can I save money on becoming a helicopter pilot in the US if I do flight hours in Mexico?" Tags="&lt;pilot-certification&gt;&lt;cost&gt;&lt;helicopter&gt;&lt;flight-school&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="102" PostTypeId="2" ParentId="64" CreationDate="2013-12-18T19:06:04.997" Score="36" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;Aeronautical Information Manual (AIM)&lt;/a&gt; is a great place to look for questions like this, and has this on the subject:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4-3-23. Use of Aircraft Lights&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Aircraft position lights are required to be lighted on aircraft&#xA;  operated on the surface and in flight from sunset to sunrise. In&#xA;  addition, aircraft equipped with an anti-collision light system are&#xA;  required to operate that light system during all types of operations&#xA;  (day and night). However, during any adverse meteorological&#xA;  conditions, the pilot-in-command may determine that the anti-collision&#xA;  lights should be turned off when their light output would constitute a&#xA;  hazard to safety (14 CFR Section 91.209). Supplementary strobe lights&#xA;  should be turned off on the ground when they adversely affect ground&#xA;  personnel or other pilots, and in flight when there are adverse&#xA;  reflection from clouds.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. An aircraft anti-collision light system can use one or more&#xA;  rotating beacons and/or strobe lights, be colored either red or white,&#xA;  and have different (higher than minimum) intensities when compared to&#xA;  other aircraft. Many aircraft have both a rotating beacon and a strobe&#xA;  light system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. The FAA has a voluntary pilot safety program, Operation Lights On,&#xA;  to enhance the see-and-avoid concept. Pilots are encouraged to turn on&#xA;  their landing lights during takeoff; i.e., either after takeoff&#xA;  clearance has been received or when beginning takeoff roll. Pilots are&#xA;  further encouraged to turn on their landing lights when operating&#xA;  below 10,000 feet, day or night, especially when operating within 10&#xA;  miles of any airport, or in conditions of reduced visibility and in&#xA;  areas where flocks of birds may be expected, i.e., coastal areas, lake&#xA;  areas, around refuse dumps, etc. Although turning on aircraft lights&#xA;  does enhance the see-and-avoid concept, pilots should not become&#xA;  complacent about keeping a sharp lookout for other aircraft. Not all&#xA;  aircraft are equipped with lights and some pilots may not have their&#xA;  lights turned on. Aircraft manufacturer's recommendations for&#xA;  operation of landing lights and electrical systems should be observed.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Prop and jet blast forces generated by large aircraft have&#xA;  overturned or damaged several smaller aircraft taxiing behind them. To&#xA;  avoid similar results, and in the interest of preventing upsets and&#xA;  injuries to ground personnel from such forces, the FAA recommends that&#xA;  air carriers and commercial operators turn on their rotating beacons&#xA;  anytime their aircraft engines are in operation. General aviation&#xA;  pilots using rotating beacon equipped aircraft are also encouraged to&#xA;  participate in this program which is designed to alert others to the&#xA;  potential hazard. Since this is a voluntary program, exercise caution&#xA;  and do not rely solely on the rotating beacon as an indication that&#xA;  aircraft engines are in operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;e. Prior to commencing taxi, it is recommended to turn on navigation,&#xA;  position, anti­collision, and logo lights (if equipped). To signal&#xA;  intent to other pilots, consider turning on the taxi light when the&#xA;  aircraft is moving or intending to move on the ground, and turning it&#xA;  off when stopped or yielding to other ground traffic. Strobe lights&#xA;  should not be illuminated during taxi if they will adversely affect&#xA;  the vision of other pilots or ground personnel.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;f. At the discretion of the pilot­in­command, all exterior lights&#xA;  should be illuminated when taxiing on or across any runway. This&#xA;  increases the conspicuousness of the aircraft to controllers and other&#xA;  pilots approaching to land, taxiing, or crossing the runway. Pilots&#xA;  should comply with any equipment operating limitations and consider&#xA;  the effects of landing and strobe lights on other aircraft in their&#xA;  vicinity.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;g. When entering the departure runway for takeoff or to “line up and&#xA;  wait,” all lights, except for landing lights, should be illuminated to&#xA;  make the aircraft conspicuous to ATC and other aircraft on approach.&#xA;  Landing lights should be turned on when takeoff clearance is received&#xA;  or when commencing takeoff roll at an airport without an operating&#xA;  control tower.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2015-11-19T01:01:42.580" LastActivityDate="2015-11-19T01:01:42.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="104" PostTypeId="1" AcceptedAnswerId="106" CreationDate="2013-12-18T19:13:36.700" Score="23" ViewCount="4884" Body="&lt;p&gt;So let's assume that I'm the sole manipulator of the flight controls in an aircraft in which I'm rated and that I fly an instrument approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What weather does the FAA require (assuming that I'm not wearing a view limiting device) in order to log the approach for currency requirements?  For instance, if I am cleared for an ILS in visual conditions, can I log it?  What if I start the approach in the clouds and break out at 1,500 ft and continue the approach?  1,000 ft?  Before/after the outer marker?  150 feet above minimums?  I think that you get the idea....  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="72" LastEditDate="2014-03-03T05:33:05.230" LastActivityDate="2017-04-20T00:35:20.917" Title="What are the weather requirements to log an instrument approach?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;instrument-flight-rules&gt;&lt;currency&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="105" PostTypeId="2" ParentId="77" CreationDate="2013-12-18T19:21:54.677" Score="26" Body="&lt;p&gt;I've heard it said that the break-even point for owning vs renting is 200 hours/year. I fly a lot less than that, but I don't like sharing my toys, so I own anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I make it a point to not actually count my cost of ownership, because it wouldn't be fun any more, but I'll give you some rough numbers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I bought a 1962 Mooney for \$30,000. That's about as cheap as it gets, and this was reflected in the condition of the plane and the high-time engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first year had it, I spent \$18,000 on an engine rebuild, new prop, new carb, new magnetos, new oil pump, and all the other firewall-forward upgrades that were required when I got the new engine. Five years later, I spent \$14,000 on new paint. It still needs a new interior, but that can wait. I spent about \$3000 at West Texas Aero installing speed upgrades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Budget \$10/hour for your next engine rebuild.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Annual inspection typically runs \$3000 to \$6000 depending on what they find wrong. I'm getting a tank resealed this year, so it's going to be an expensive one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parking runs typically \$50-\$100/month, depending on where you are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insurance for my old crate runs \$750/year. Expect to pay more for a nicer plane or if you have less experience. &lt;em&gt;Note:&lt;/em&gt; get a commercial license; it will pay for itself in reduced insurance in the long run.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think gas will typically run \$5-6/gallon, depending on a lot of factors. My Mooney burns around 9.5gph, and flies 142 kts so it's really economical in that respect (and the main reason I don't upgrade).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Light twins are cheap to buy, but that's because their cost of ownership is through the roof. A low-time pilot can expect to pay \$12,000/year for insurance and the annual inspection will also be a back-breaker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used to have money. Now I have an airplane.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="72" LastEditDate="2014-04-23T12:23:16.033" LastActivityDate="2014-04-23T12:23:16.033" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="106" PostTypeId="2" ParentId="104" CreationDate="2013-12-18T19:23:50.737" Score="20" Body="&lt;p&gt;Update with relevant info from &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2015/InFO15012.pdf&quot; rel=&quot;noreferrer&quot;&gt;InFO 15012&lt;/a&gt; (I'm skipping the FTD portions as not relevant to the question, and including the simulated parts but &lt;em&gt;italicizing&lt;/em&gt; them as they're useful but also not relevant). Translated, you can log an approach when:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;it is flown solely by reference to instruments, and&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;it is flown in IMC, and Actual Instrument time is logged, or&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;the PF is using a view-limiting device, and Simulated Instrument time is logged;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;you must fly the &lt;strong&gt;complete approach&lt;/strong&gt; from a feeder or the IAP (or Vectors to Final) and remain established the whole time. This means you fly initial, intermediate, and final segments, unless you're on vectors.&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;if flying the approach in IMC, &lt;strong&gt;you may log an approach that&lt;/strong&gt;:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;continues to DA/DH or MDA in actual&lt;/strong&gt;, or &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;becomes VMC before DA/DH or MDA, provided you are inside the FAF&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;if simulating the approach, you must continue to the DA/DH or MDA under the hood (or other VLD);&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;That's pretty much it. Here's the source text:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A pilot may log an IAP for currency or training when the pilot&#xA;  accomplishes the IAP in accordance with the following conditions:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must operate that&#xA;  aircraft or authorized training device solely by reference to&#xA;  instruments [§ 61.51(g)(1)];&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must be established on&#xA;  each required segment of the IAP to the minimum descent altitude (MDA)&#xA;  or decision altitude/decision height (DA/DH);&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft simulating instrument flight conditions, a flight simulator, a flight training device, or an&#xA;  aviation training device, the simulated instrument meteorological&#xA;  conditions (IMC) must continue to MDA or DA/DH; and&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, the flight must be conducted under actual or simulated instrument flight conditions [§ 61.51(g)(1)].&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft maneuvering in IMC, and the aircraft transitions from IMC to visual flight conditions on the final approach&#xA;  segment of the IAP prior to or upon reaching MDA or DA/DH.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Previously, I linked to Rod Machado, who cites the FAA in an &lt;a href=&quot;http://www.rodmachado.com/_become_private_pilot/logging_flight_time.php&quot; rel=&quot;noreferrer&quot;&gt;answer&lt;/a&gt; to this that I quite like, and which was pretty frequently referred to when I was instructing at a flight school:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once you have been cleared for and have initiated an instrument approach in IMC, you may log that approach for instrument currency, regardless of the altitude at which you break out of the clouds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...but this is not the latest knowledge anymore. It's functionally pretty close to the InFo rules for IMC approaches, though!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-10-02T20:48:46.290" LastActivityDate="2015-10-02T20:48:46.290" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="107" PostTypeId="1" AcceptedAnswerId="110" CreationDate="2013-12-18T19:44:51.220" Score="19" ViewCount="54724" Body="&lt;p&gt;I've heard that some pilots have this difficulty to determine the correct use of both features. So, which is the difference between using the vertical speed, instead using the flight level change during a descent? When, and how to use it?  &lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="39" LastEditDate="2013-12-19T00:22:59.720" LastActivityDate="2017-12-10T20:06:14.683" Title="Flight Level Change or Vertical Speed - When to use it?" Tags="&lt;flight-level&gt;&lt;vertical-speed&gt;&lt;descent&gt;&lt;autopilot&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="108" PostTypeId="2" ParentId="64" CreationDate="2013-12-18T19:51:39.433" Score="4" Body="&lt;p&gt;FARs are available &lt;a href=&quot;http://www.faa.gov/regulations_policies/faa_regulations/&quot; rel=&quot;nofollow&quot;&gt;online here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;91.205 says for night flight, you need position lights (the red, green, white lights), anti-collision lights, and a landing light if flown for hire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IIRC, it is customary, but not required, to activate the flashing red beacon any time the engine is running, as a warning to people on the ground. This might be mentioned in the AIM, but I'm pretty sure it's not in the FARs.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="65" LastEditDate="2015-03-10T14:18:09.380" LastActivityDate="2015-03-10T14:18:09.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="109" PostTypeId="2" ParentId="107" CreationDate="2013-12-18T19:58:43.327" Score="10" Body="&lt;p&gt;Just MHO: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical speed should never be used when climbing because you could stall if insufficient power is added for the requested climb rate. Using FLC when climbing guarantees you maintain the best airspeed (best rate or best angle, depending on the situation)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, when descending I always use VS mode because it gets you down to the proper altitude in time (if you've calculated the required VS before starting your descent). It also prevents physical discomfort for you and your passengers. If you use FLC during the descent you have to be very careful with power in order not to exceed safe airspeeds (in addition to the discomfort caused by excessive descent rates)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not an expert opinion but just a personal opinion...&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2013-12-18T19:58:43.327" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="110" PostTypeId="2" ParentId="107" CreationDate="2013-12-18T20:02:01.477" Score="14" Body="&lt;p&gt;&lt;strong&gt;FLC mode maintains airspeed&lt;/strong&gt; during a climb or descent, while &lt;strong&gt;VS mode maintains a specific vertical speed&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often air traffic controllers will request that you &quot;maintain 250 knots in the descent&quot; or something to that effect, which is much easier to achieve when using Flight Level Change. As another answer points out, by maintaining airspeed, climbs are made safer as the autopilot will not attempt to maintain a rate of climb regardless of whether or not the airspeed is safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FLC mode is typically only available in advanced autopilots, and as far as I know they need to connect to an Air Data Computer to get the necessary information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to use FLC would depend on the equipment available to you: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;aircraft with auto throttle will maintain speed and an appropriate rate of descent automatically. &lt;/li&gt;&#xA;&lt;li&gt;for aircraft without auto throttle you'd set your target altitude, enable FLC, adjust your target speed if needed, and set your throttle for climb or descent to maintain the desired altitude change rate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm referencing the Garmin GFC700 as it's the only autopilot I've used with FLC mode, but I imagine the same steps and rules would apply.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="1961" LastEditDate="2014-07-01T18:38:56.803" LastActivityDate="2014-07-01T18:38:56.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="111" PostTypeId="2" ParentId="82" CreationDate="2013-12-18T20:05:41.237" Score="3" Body="&lt;p&gt;&lt;strong&gt;True north&lt;/strong&gt; (geodetic north) is the direction along the earth's surface towards the geographic North Pole.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;True geodetic north usually differs from &lt;strong&gt;magnetic north&lt;/strong&gt; (the direction a compass points toward the magnetic north pole), and from grid north (the direction northwards along the grid lines of a map projection). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cx3Wbm.gif&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Magnetic declination&lt;/strong&gt; is the angle between compass north (the direction the north end of a compass needle points) and true north (the direction along the earth's surface towards the geographic North Pole). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to get &lt;strong&gt;Magnetic Heading&lt;/strong&gt;, look at your compass. To get the true heading, you will need to look to a WAC chart, and depending on your position, add or remove degrees according to your position's &lt;strong&gt;Magnetic declination&lt;/strong&gt; .&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="97" LastEditDate="2015-05-03T04:03:03.070" LastActivityDate="2015-05-03T04:03:03.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="112" PostTypeId="1" CreationDate="2013-12-18T20:37:00.817" Score="3" ViewCount="1756" Body="&lt;p&gt;Is it possible to briefly summarize how a commercial plane navigation system operates to a layperson (e.g. a passenger)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft takes off, reaches a certain altitude, and then lands perfect on a runway somewhere else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the navigation system affect this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do pilots know where to go and where to land?&lt;/p&gt;&#xA;" OwnerUserId="42" LastEditorUserId="72" LastEditDate="2014-03-04T02:07:14.627" LastActivityDate="2014-03-04T02:07:14.627" Title="How does aircraft navigation work?" Tags="&lt;navigation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2013-12-19T00:41:45.633" ContentLicense="CC BY-SA 3.0" />
  <row Id="114" PostTypeId="1" CreationDate="2013-12-18T20:43:07.557" Score="11" ViewCount="412" Body="&lt;p&gt;Does the FAA regulate drones at this time?&lt;br&gt;&#xA;Maybe they regulate only a certain class / size of UAV / UAS?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is drone regulation to the level that traffic is managed through ATC?&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="57" LastEditDate="2014-01-30T23:34:09.227" LastActivityDate="2014-09-02T13:02:29.153" Title="How is drone (UAS) traffic regulated in the US?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="115" PostTypeId="1" CreationDate="2013-12-18T20:43:18.860" Score="14" ViewCount="8292" Body="&lt;p&gt;&lt;strong&gt;What is the average range, accuracy, and update frequency of radar systems used to monitor airspace in the USA?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm primarily interested in capabilities for tracking smaller general aviation aircraft without enhanced return data channels like ADS-B, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please include sources, if possible. As an example, by looking at TRACON/ASR data exports (CDR), these systems &lt;em&gt;appear&lt;/em&gt; to update an aircraft echo at about a 4.7 second frequency, give or take a few tenths. However, I not been been able to source or verify my findings or similar statements made by expert witnesses in litigation cases.&lt;/p&gt;&#xA;" OwnerUserId="118" LastEditorUserId="69" LastEditDate="2014-01-18T17:05:39.417" LastActivityDate="2015-05-09T11:30:36.167" Title="What is the range and accuracy of ATC radar systems?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;&lt;radar&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="116" PostTypeId="2" ParentId="100" CreationDate="2013-12-18T20:46:08.687" Score="10" Body="&lt;p&gt;As far as I can tell from the FARs as long as your training is performed by an FAA-certificated flight instructor and complies with the appropriate requirements of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=271233c94ed1f4118329f39cc2ebc7bf&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2&quot;&gt;part 61&lt;/a&gt; of the FARs you could theoretically do parts of your (primary/private) training anywhere you want, get all your endorsements, then come back to the USA to take your checkride and get a regular US (FAA) pilot's license for the appropriate category/class of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a practical standpoint I think this may be more work than the money you save.&lt;br&gt;&#xA;If you do your pre-solo training in Mexico any instructor you come to in the US is going to want to fly with you a bit before they endorse you to solo.&lt;br&gt;&#xA;If you try to do the whole thing in Mexico you would have to comply with Mexico's flight training requirements (Medical, student pilot certification, solo endorsements, etc. - about which I know basically nothing) as well the US FAA's requirements (like holding a US student pilot certificate with appropriate endorsements prior to taking your checkride). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that the procedure is a little different if you want to get a &lt;em&gt;Mexican&lt;/em&gt; pilot's certificate and then &lt;em&gt;convert&lt;/em&gt; it to a US/FAA certificate (that's all detailed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=271233c94ed1f4118329f39cc2ebc7bf&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.2.1.10&quot;&gt;FAR 61.75&lt;/a&gt; if you're interested. It doesn't sound like that's what you want to do, but at least as far as the regulations go that seems to be a more well-traveled path and something your local FSDO could probably advise you on - at the very least it would involve paperwork, possibly also a checkride).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'd like to say a couple of words on &lt;a href=&quot;http://en.wikipedia.org/wiki/Principles_of_learning#Primacy&quot;&gt;Primacy&lt;/a&gt; since we're talking about training: &lt;em&gt;Where you learn and the procedures you learn first will form the foundation of your aviation knowledge.&lt;/em&gt;&lt;br&gt;&#xA;What that ultimately means for you depends on how different the regulations are where you do your training versus where you will do most of your flying. The FAA has been moving to standardize our procedures to be more in line with ICAO standards for a number of years now, but there are still differences and you may have to re-learn some of the regulatory bits of aviation if you did the bulk of your training elsewhere. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes sense &lt;em&gt;to me&lt;/em&gt; to learn to fly where you intend to fly -- ideally in the same region (a sleepy corner of the midwest versus lower New York's airspace can be a culture shock!) but if cost is a factor find the best bang for your training buck in the airspace system you'll be spending most of your time in.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-18T20:46:08.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="117" PostTypeId="2" ParentId="114" CreationDate="2013-12-18T20:46:41.287" Score="2" Body="&lt;p&gt;As of yet, I cannot tell &lt;a href=&quot;http://www.ainonline.com/aviation-news/2013-04-05/new-rtca-committee-seeks-expedite-uas-standards&quot; rel=&quot;nofollow&quot;&gt;if drone traffic is regulated&lt;/a&gt;, but I do find that &lt;a href=&quot;http://www.rtca.org/calendar_day.asp?date=2/24/2014&amp;amp;event=120&quot; rel=&quot;nofollow&quot;&gt;the FAA has created a committee&lt;/a&gt; to design the appropriate architecture and guidelines.&lt;/p&gt;&#xA;" OwnerUserId="57" LastActivityDate="2013-12-18T20:46:41.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="118" PostTypeId="1" AcceptedAnswerId="125" CreationDate="2013-12-18T20:54:32.393" Score="11" ViewCount="1118" Body="&lt;p&gt;Based on the reading I've been doing of FAA's Next Generation Air Traffic Control (&lt;a href=&quot;http://en.wikipedia.org/wiki/Next_Generation_Air_Transportation_System&quot;&gt;NextGen&lt;/a&gt;) plans, I've been wondering if and how radar systems will continue to be used for ATC as NextGen rolls out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it correct to assert that radar coverage will effectively become a less precise, backup only, data feed? I am suggesting this because my understanding (which could easily be incorrect) is that ADS-B will mandated for most (everyone?) and so aircraft will be actively reporting their precise position without the need for a radar track.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Will existing radar coverage eventually be phased out?  Seems unlikely due to airspace security issues alone. But are there any other reasons to keep radar coverage?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="118" LastEditorUserId="118" LastEditDate="2013-12-18T22:02:25.267" LastActivityDate="2015-05-09T11:31:53.463" Title="How will radar systems be used in FAA's NextGen ATC plans?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="119" PostTypeId="1" AcceptedAnswerId="151" CreationDate="2013-12-18T20:55:26.277" Score="18" ViewCount="3367" Body="&lt;p&gt;The Boeing 737 was originally designed in the 1960's and flew into the 1980's before a major redesign (the 737-700, -800, and -900 models) was implemented.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming up in a few years will be the next major revamp of the line as the 737-Max series (737-7, 737-8, and 737-9). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What major changes have been incorporated in these revisions?&lt;/p&gt;&#xA;" OwnerUserId="80" LastEditorUserId="97" LastEditDate="2014-01-13T02:09:30.823" LastActivityDate="2017-09-28T00:07:02.257" Title="With the upgrade of the 737 to the Max model, what major changes are incorporated?" Tags="&lt;boeing&gt;&lt;boeing-737&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="120" PostTypeId="1" AcceptedAnswerId="122" CreationDate="2013-12-18T20:55:48.920" Score="17" ViewCount="6156" Body="&lt;p&gt;Civilians fly kites for entertainment.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a limit, after which the kite is considered an aircraft and becomes regulated?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is a kite considered a balloon, after a certain size?  Do technology or other control apparatus make the distinction?  Is it purely height-based, and size is (mostly?) irrelevant?&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="19" LastEditDate="2016-07-28T16:45:05.843" LastActivityDate="2018-12-29T03:37:34.243" Title="Is there any size of tethered kite that is regulated by the FAA?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="121" PostTypeId="1" AcceptedAnswerId="408" CreationDate="2013-12-18T21:11:36.750" Score="6" ViewCount="226" Body="&lt;p&gt;Do grounding systems have any standards or conventions?  Is tethering specified in any way?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can understand the engineering aspects of the question, but I am wondering about &lt;em&gt;regulation&lt;/em&gt; or &lt;em&gt;convention&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;.....I have a suspicion that any kind of formal or experimental craft / flyer is probably not regulated, so long as it doesn't 'escape' and remain in the air while it drifts into a controlled airspace.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;I've participated in many balloon flights, and have never seen anything specific with this, so I suspect the answer is too simple ('no') or that this question is otherwise not well formatted&lt;/li&gt;&#xA;&lt;li&gt;this question may be too close to the history of experimental-craft&lt;/li&gt;&#xA;&lt;li&gt;I would appreciate help with proposing tags for this question&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="57" LastEditorUserId="57" LastEditDate="2013-12-19T14:13:42.543" LastActivityDate="2014-06-20T16:26:48.117" Title="Are there standard ground-tether systems for unpowered aircraft?" Tags="&lt;unpowered&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="122" PostTypeId="2" ParentId="120" CreationDate="2013-12-18T21:12:16.360" Score="17" Body="&lt;p&gt;As one of my instructors was fond of pointing out, there's pretty much a regulation for everything -- &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.15&amp;amp;idno=14#14:2.0.1.3.15.2&quot;&gt;in the US kites and balloons would be covered under FAR part 101&lt;/a&gt; which is pretty short and to the point as far as government regulations go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big rules regarding kites/balloons kick in for a kite &quot;over 5 pounds&quot; or a balloon &quot;over 6 feet in diameter / 115 cubic feet of gas capacity&quot;, and are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You have to keep them at least 500 feet below any clouds.&lt;/li&gt;&#xA;&lt;li&gt;You have to keep them &lt;em&gt;less than&lt;/em&gt; 500 feet above the ground.&lt;/li&gt;&#xA;&lt;li&gt;You must be at least 5 miles from the boundary of any airport.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If your kite/balloon is going to be more than 150 feet above the surface you're also supposed to coordinate with the closest ATC facility (who would theoretically put out a NOTAM saying &quot;John Doe is going to be flying a kite/balloon/thingy here, between these hours. Please try not to hit it.&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some lighting requirements (if you fly the balloon/kite at night), and visibility requirements (but really, who wants to fly a kite in less than 3 miles visibility? That seems like pretty lousy kite weather.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a favor to your local pilot community (and to prevent having your wayward kite dragged off by a Cessna on short final) it's probably best to observe the three &quot;big rules&quot; above regardless of the size of your kite - a 6-ounce piece of balsa and cellophane can still make a lot of people's days more interesting if it appears in an unexpected location.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-18T21:12:16.360" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="123" PostTypeId="2" ParentId="115" CreationDate="2013-12-18T21:23:28.760" Score="5" Body="&lt;p&gt;This is a general answer, not specific applicable to the situation in the USA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several types of radars in use to monitor airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically you can distinguish two classes of radar:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Primary radar&lt;/strong&gt; does not require the aircraft to carry a transponder, it is a form of non-cooperative surveillance.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Secondary radar&lt;/strong&gt; on the other hand requires the aircraft to carry a transponder; the transponder replies to interrogations from the radar. This is called cooperative surveillance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Radars operate basically by line-of-sight, however due to atmospheric effects the radio waves follow the curvature of the earth to some degree. Aircraft flying low are quickly below the horizon, but aircraft at FL450 can be detected on secondary radar at ranges up to 300NM if the radar is operated for such range. Typically the range is less. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the further the range that a radar needs to look, the slower it rotates. An airport surface radar may rotate as fast as twice per second, long range en-route radars can go as slow as once per 12 seconds. For typical TMA / TRACON use, 5 seconds would be in the right ballpark, for en-route 8 seconds will be about right. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The accuracy depends on the type of antenna, whether it is primary or secondary radar, and the distance of the aircraft from the radar head. The accuracy of the distance measurement are not so much affected by the range, and varies from about 5 meters to 300 meters. However, atmospheric circumstances can degrade these figures, especially at long range. The across beam accuracy is very much dependent on the distance from the antenna due to limited angular accuracy of the radar. The further you get, the worse the across beam accuracy becomes.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-09T11:30:36.167" LastActivityDate="2015-05-09T11:30:36.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="124" PostTypeId="2" ParentId="112" CreationDate="2013-12-18T21:25:42.217" Score="12" Body="&lt;p&gt;&lt;strong&gt;How do you navigate in your car?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before you depart, you have a general understanding of which direction you're going.&lt;br&gt;&#xA;(&lt;em&gt;the supermarket is to the east of my house, about 3 miles.  I believe it will take me about 5 minutes to get there&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you start driving, you keep your eyes open looking for information and clues.&lt;br&gt;&#xA;(&lt;em&gt;The yellow lines on the road denote a two-way street.  Certain landmarks are familiar and expected.&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you proceed, you may refer to your car dashboard to make sure things are as expected&lt;br&gt;&#xA;(&lt;em&gt;My speed is 43MPH.   I had planned for 45MPH... pretty close.  My engine is running at 2,500 RPM, which is appropriate&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may have advanced instruments as well&lt;br&gt;&#xA;(&lt;em&gt;The GPS in my car is telling me to take the next right turn, and go 1/2 mile&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;&lt;strong&gt;Its very much the same with flying.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots have pre-flight preparation where they go over a general plan.&lt;br&gt;(&lt;em&gt;we're going to fly north, on a heading of about 025 for 3 hours.  We'll be passing over a large lake, and landing at our destination with a city off to our left&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As they move towards the runway, they look for other airplanes, read the signs around the  runway, and refer to their maps.&lt;br&gt;&#xA;(&lt;em&gt;I see a sign indicating I'm on taxi-way Bravo, approaching Runway 31.  I see yellow markings on the pavement indicating I should get permission before I cross&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once they take off, they look at their instruments to verify they're going at the expected speed, altitude and direction.&lt;br&gt;&#xA;(&lt;em&gt;Altitude is 35,000 feet, as planned.  Engines are at the right pressure, and speed is 440 knots, as expected&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can look out the window for large landmarks, lakes, mountains, cities, etc.&lt;br&gt;&#xA;(&lt;em&gt;I'm passing by the mountain I saw on the map.  I see the river valley below me, and a large city ahead of me, just like I planned&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They may use advanced services like GPS Navigation, Radar and radio signals to help navigate.&#xA;(&lt;em&gt;My GPS is showing my position and direction.  It says to turn a little to the right to stay on course.   The navigation radio says I'm 25 Nautical Miles away from the radio transmitter&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And they can talk to Air Traffic Control who can observe them on radar, and advise them to make adjustments to their course for navigation, and to stay separated from other airplanes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If they cannot see out the window, navigation does become a bit more complicated, and reliant on Instruments, GPS, Radar and Radio.&lt;p&gt;But given a very careful plan of &lt;em&gt;&quot;Fly for exactly 31 minutes, at exactly a heading of 027, at exactly a speed of 130Kts&quot;&lt;/em&gt;, it is pretty remarkable how close the airplane will end up to the intended destination.&lt;p&gt;&#xA;That process is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Dead_reckoning&quot;&gt;Dead Reckoning&lt;/a&gt;.  It requires some detailed advanced planning, but isn't that difficult.   Combining Dead Reckoning with Instrument flying, and pilots can go through zero-visibility and still come out at the intended location.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2013-12-18T21:38:45.260" LastActivityDate="2013-12-18T21:38:45.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="125" PostTypeId="2" ParentId="118" CreationDate="2013-12-18T21:46:29.477" Score="4" Body="&lt;p&gt;Under the &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/FR-2010-05-28/pdf/2010-12645.pdf&quot; rel=&quot;nofollow&quot;&gt;ADS-B rule&lt;/a&gt; of the FAA aircraft operating in Classes A, B, and C airspace, as well as certain other specified classes of airspace&#xA;within the U.S. National Airspace System are required to operate ADS-B Out avionics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that these aircraft can be tracked without the use of radar. These ADS-B tracks will be more accurate than radar tracks and have a higher update rate. However for reasons of integrity, continuity of service and security, radar will continue to provide coverage. Currently a lot of airspace is covered by multiple radar layers, the introduction of ADS-B allows for a reduction in redundant radar coverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft not equipped with ADS-B (operating outside of class A,B, or C airspace) will be tracked using radar. The radar tracks will be broadcast on TIS-B (Traffic Information Service - Broadcast) so that aircraft with ADS-B In receivers detect these aircraft as well. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-09T11:31:53.463" LastActivityDate="2015-05-09T11:31:53.463" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="126" PostTypeId="1" CreationDate="2013-12-18T21:53:58.907" Score="17" ViewCount="35334" Body="&lt;p&gt;Let's say I call up Wx and have the wind direction and I know the runway headings from my charts and the pattern is empty. I can do the math, but it's tedious and slow and even worse when there are multiple runways. This is what I usually do:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Runways are 13 and 31&lt;/li&gt;&#xA;&lt;li&gt;Wind is 253° which rounds to 25&lt;/li&gt;&#xA;&lt;li&gt;$25-13=12$&lt;/li&gt;&#xA;&lt;li&gt;$31-25=6$&lt;/li&gt;&#xA;&lt;li&gt;I'm going to use Runway 31&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is there a trick to determine best runway quickly without doing the math?&lt;/p&gt;&#xA;" OwnerUserId="120" LastEditorUserId="72" LastEditDate="2014-04-23T12:24:02.037" LastActivityDate="2019-01-22T22:35:11.797" Title="What's a quick way to determine which runway to use?" Tags="&lt;runways&gt;&lt;wind&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="127" PostTypeId="2" ParentId="126" CreationDate="2013-12-18T21:58:58.180" Score="7" Body="&lt;p&gt;In uncontrolled airports I've avoided problems simply by asking on CTAF which runway is in use when 10-7SM out. This has worked out well because often times there are aircraft in the pattern on the wrong runway (from the perspective of crosswind) because conditions changed and traffic has been busy, or someone is just doing their own thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've even had a unicom station respond with a recommendation when nobody in the air responded. It doesn't hurt to ask and if you get no response a quick glance at the heading indicator can save you the math by just visualizing the runways over the indicator and choosing the one that's closest to the wind.&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2013-12-18T21:58:58.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="128" PostTypeId="2" ParentId="126" CreationDate="2013-12-18T22:03:45.567" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a trick to determine best runway quickly without doing the math?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aside from &quot;Asking the other pilots in the pattern / UNICOM&quot;, none I'm aware of.&lt;br&gt;&#xA;The closest thing to a &quot;trick&quot; I can offer you if you're going in to a completely unattended field are the following suggestions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If your &lt;a href=&quot;http://en.wikipedia.org/wiki/Heading_indicator&quot; rel=&quot;noreferrer&quot;&gt;directional gyro (DG)&lt;/a&gt; has a heading bug, set the heading bug to the wind direction.&lt;br&gt;&#xA;Now find the runway alignment closest to the bug. That's the runway you want.&lt;br&gt;&#xA;(If your DG doesn't have a heading bug you may still be able to do this visually easier than doing math - of course this relies on you flying in a plane with a  DG or a vertical card compass...).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Break out your &lt;a href=&quot;http://en.wikipedia.org/wiki/E6B&quot; rel=&quot;noreferrer&quot;&gt;E6B&lt;/a&gt;, dial in the wind direction, and find the closest runway heading.&lt;br&gt;&#xA;Same logic as (1), but for when you're stuck in a Piper Cub with only the wet compass.&lt;br&gt;&#xA;One drawback - it only works with mechanical flight computers...&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you have your sectional out, lay your pen or ruler on it to show the wind direction.&lt;br&gt;&#xA;See which runway alignment is closest to the ruler. That's the runway you want.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Count on your fingers.&lt;br&gt;&#xA;(Seriously, this is what I do most of the time. I'm an engineer, I can't add and subtract!)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-03-03T15:06:10.357" LastActivityDate="2015-03-03T15:06:10.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="129" PostTypeId="1" AcceptedAnswerId="16310" CreationDate="2013-12-18T22:13:07.313" Score="11" ViewCount="5861" Body="&lt;p&gt;There are a number of different ways of taking off with a powerless hang glider, the most commonly used being either running down a hill or jumping off a cliff/platform. This is how I learned to hang glide and is the standard way of getting airborne for most hang gliders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I recently moved to Houston, Texas which is extremely flat. As far as I can tell, there isn't a single hill tall enough to take off from within a 100 mile radius of where I live.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I safely get airborne when I am on flat ground?&lt;/p&gt;&#xA;" OwnerUserId="115" LastEditorUserId="34686" LastEditDate="2019-07-24T17:40:07.010" LastActivityDate="2019-07-24T20:09:10.397" Title="How can a hang glider take off from flat ground?" Tags="&lt;takeoff&gt;&lt;glider&gt;&lt;ultralight&gt;&lt;unpowered&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="130" PostTypeId="2" ParentId="10" CreationDate="2013-12-18T22:20:28.110" Score="10" Body="&lt;p&gt;Yes, log it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your logbook is &lt;em&gt;your&lt;/em&gt; record of your flight experience. Use a line in your logbook to remember a flight with a friend or a warbird flight you took at an air show. If I'm a passenger in the right seat of a small aircraft and I'm paying attention I am probably learning something. If I'm currently working towards my instrument rating and I'm sitting in the backseat of a friend's instrument rating lesson then I'm almost certainly learning things that I wouldn't get while actually flying the plane. Record those experiences for yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the numbers columns for that entry are going to be empty. No landings, no flight time, none of that. You wouldn't want to accidentally use those flights for currency or ratings. AOPA has a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Learn-to-Fly/Logging-Cross-Country-Time/Logbooks-and-Logging-Time.aspx&quot; rel=&quot;noreferrer&quot;&gt;good article interpreting the FARs rules on logging time&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you can use an empty column for passenger numbers or just use your comments section.&lt;/p&gt;&#xA;" OwnerUserId="120" LastActivityDate="2013-12-18T22:20:28.110" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="132" PostTypeId="2" ParentId="126" CreationDate="2013-12-18T22:28:42.853" Score="20" Body="&lt;p&gt;This might take a few seconds longer, but it's math-free: On your kneeboard, draw a quadrant (like this: +). Draw a line through it for your runway(s). Draw an arrow to represent the wind. The answer will be apparent. Do it enough times, and you'll be able to visualize the drawing without actually doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also a great technique for calculating holds.&lt;/p&gt;&#xA;" OwnerUserId="50" LastActivityDate="2013-12-18T22:28:42.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="133" PostTypeId="1" AcceptedAnswerId="138" CreationDate="2013-12-18T22:40:37.170" Score="13" ViewCount="1839" Body="&lt;p&gt;Due west of KLAS and Death Valley are a large number of MOAs and Restricted areas. On the sectional and terminal area charts, there are thin magenta lines snaking over some of the mountain tops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do those lines represent? They don't seem to be a mode C veil of any sort, and the legend doesn't otherwise mention a thin magenta line without spikes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3G7RA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="50" LastEditorUserId="167" LastEditDate="2014-05-14T01:57:40.710" LastActivityDate="2014-05-14T01:57:40.710" Title="What are those thin magenta lines on the Sectional / Terminal Area Chart near Death Valley?" Tags="&lt;aeronautical-charts&gt;&lt;symbology&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="134" PostTypeId="1" CreationDate="2013-12-18T22:46:31.513" Score="15" ViewCount="800" Body="&lt;p&gt;Since the retirement of the Concorde and the Tupolev Tu-144, there aren't any civilian airplanes (passengers carrier or business jet) flying supersonic. I heard that Dassault and SAAB had rather advanced studies on this topic but abandoned them due to various problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have current references indicating that an aircraft manufacturer plans to develop a supersonic transport aircraft?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="27883" LastEditDate="2018-01-13T15:18:49.730" LastActivityDate="2018-01-13T15:18:49.730" Title="Are there any serious plans for a new supersonic civilian aircraft?" Tags="&lt;supersonic&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="0" ClosedDate="2013-12-27T20:19:55.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="136" PostTypeId="1" AcceptedAnswerId="141" CreationDate="2013-12-18T22:54:56.057" Score="6" ViewCount="430" Body="&lt;p&gt;I know that to be allowed to fly an aircraft has to be certified by an agency and that this one is not the same for European or American (for instance) aircraft. What are the different steps that an aircraft designed to fly in Europe has to go through in order to be certified? Proof on the paper of some features? Ground tests (which one)? Flight tests (which one)?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="7532" LastEditDate="2015-12-15T22:30:19.640" LastActivityDate="2016-03-17T20:47:38.223" Title="What are the different steps to certify a new aircraft in Europe?" Tags="&lt;aircraft-certification&gt;&lt;easa-regulations&gt;&lt;flight-testing&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="137" PostTypeId="1" AcceptedAnswerId="139" CreationDate="2013-12-18T22:58:39.997" Score="23" ViewCount="4903" Body="&lt;p&gt;When flying in an Airbus, I often (if not always) hear a weird sound before the aircraft starts to accelerate for taking off. From where exactly does this sound come from? Why doesn't it appear on other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="39" LastEditDate="2013-12-21T02:36:39.807" LastActivityDate="2013-12-21T02:36:39.807" Title="What is this sound from Airbus aircraft before take off?" Tags="&lt;airbus&gt;&lt;passenger&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="138" PostTypeId="2" ParentId="133" CreationDate="2013-12-18T23:09:25.210" Score="13" Body="&lt;p&gt;Those lines denote areas of the MOA which have altitude exclusions different from what is listed on the chart's MOA table. In this case:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MOA Excludes Airspace 3000' AGL &amp;amp; Below&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notice the same style magenta lines are drawn in circles around airports in the MOA which also have the same style remark excluding a specific portion of the airspace.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-18T23:09:25.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="139" PostTypeId="2" ParentId="137" CreationDate="2013-12-18T23:14:42.787" Score="33" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.boston.com/community/blogs/askthepilot/2013/09/curious_flyers_want_to_know_wh.html&quot;&gt;Ask the Pilot&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Almost every frequent flyer has encountered this sound at one time or&#xA;  another. [...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It happens on twin-engine Airbus models: the A320 series (includes the&#xA;  subvariants A319 and A321) and the larger A330. [...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;What you hear is a device called the power transfer unit, or PTU,&#xA;  which is designed to ensure adequate hydraulic pressures during&#xA;  single-engine operations. [...] Since it is activated only when the&#xA;  pressure falls below a certain level, the PTU cycles on and off, on&#xA;  and off, on and off.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Some Boeing aircraft also employ a PTU, but the operation is slightly&#xA;  different and it doesn’t bark like a dog.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Another noise peculiar to Airbus models is a shrill, prolonged whine&#xA;  heard at the gate prior to departure and again after landing. This is&#xA;  an electric hydraulic pump used to open and close the cargo doors.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-18T23:14:42.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="140" PostTypeId="1" AcceptedAnswerId="11294" CreationDate="2013-12-18T23:14:45.110" Score="14" ViewCount="2941" Body="&lt;p&gt;As a private pilot I have zero knowledge about how big jets are being flown so I was a little surprised to see that smaller Airbuses (A32x) only use spoilers for roll control on final approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the initial phase of the approach ailerons are being used but at a certain point they stay in the neutral position and roll is controlled by the spoilers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I mentioned this to the pilot when exiting the aircraft he was a little annoyed by the question and he said I must have seen it wrong. I've seen this numerous times since then so I'm pretty sure I wasn't mistaken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this actually how the spoilers are used on approach, and if so, why?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="1696" LastEditDate="2015-02-19T20:55:19.880" LastActivityDate="2019-02-27T23:22:37.063" Title="Is roll control achieved exclusively with spoilers on an A320 on final approach?" Tags="&lt;airbus&gt;&lt;ailerons&gt;&lt;spoilers&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="141" PostTypeId="2" ParentId="136" CreationDate="2013-12-18T23:36:49.793" Score="5" Body="&lt;p&gt;The EASA &lt;a href=&quot;http://www.easa.europa.eu/agency-measures/certification-specifications.php&quot;&gt;certification requirements&lt;/a&gt; are all publicly available online. Actually proving that an aircraft meets those criteria will certainly include all the steps you mentioned although exactly what happens probably depends a lot on the specific aircraft and manufacturer.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-18T23:36:49.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="142" PostTypeId="2" ParentId="136" CreationDate="2013-12-19T00:01:16.527" Score="3" Body="&lt;p&gt;It does really depend on where the aircraft is being designed and manufactured. The initial type certification is done with the authorities in the State of Design / Manufacture. If that country happens to be outside of the EU, EASA will identify what extra proof of compliance will be required to fulfil the European certification requirements.   &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2013-12-19T00:01:16.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="144" PostTypeId="2" ParentId="67" CreationDate="2013-12-19T00:03:04.447" Score="7" Body="&lt;p&gt;I'll have a go at answering this.  It's confused by the UK's transition from the JAA to EASA licensing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My JAR-PPL(A), issued in 2011, is valid for 5 years so yes, I assume yours will have expired.  My FRTOL is valid for 10 years so presumably yours will have expired too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirements are hidden in &lt;a href=&quot;http://www.caa.co.uk/docs/33/CAA_CAP%20804.pdf&quot;&gt;CAP 804&lt;/a&gt; ([Deep breath] Section&amp;nbsp;7, Part&amp;nbsp;B (Schedule&amp;nbsp;7) Part&amp;nbsp;C, Section&amp;nbsp;2, Paragraph&amp;nbsp;9-(1)(c)).  Renewing an expired licence (single-engined/single pilot aeroplane) seems to require meeting FCL.740.A of Part-FCL (type rating) and Appendix 9 to Part–FCL (skills test).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe this effectively means you'll have to undertake training to ensure you can pass the skills test, pass it and pay to have your licence reissued.  (Not forgetting the medical.)   You will end-up with a part-FCL PPL (which do not expire).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about having to retake the FRTOL tests, I think you may just have to re-sit the theory (PPL comms), fill out a form and pay but the answer is probably in CAP 804 somewhere!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The easiest/best thing to do would be to pop-in to your local friendly FTO and discuss with them...&lt;/p&gt;&#xA;" OwnerUserId="109" LastActivityDate="2013-12-19T00:03:04.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="145" PostTypeId="1" AcceptedAnswerId="429" CreationDate="2013-12-19T00:15:04.023" Score="5" ViewCount="849" Body="&lt;p&gt;The FAA will open up to flying civilian drones in 2015. Should we get pilot licenses to be ready for this? if so, is there a difference between plane or helicopter pilot license?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Links related:&lt;/strong&gt;&lt;br&gt; &#xA;&lt;a href=&quot;http://www.californiareport.org/archive/R201310230850/b&quot; rel=&quot;nofollow&quot;&gt;NASA Helps Draw Up Rules for Flying Drones in the U.S&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.latimes.com/nation/la-na-drones-rules-20131108,0,3969978.story#axzz2nsJ4jkiS&quot; rel=&quot;nofollow&quot;&gt;FAA making plans for drone flights in U.S.&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://endthelie.com/2013/01/30/u-s-colleges-begin-offering-more-drone-piloting-programs-to-keep-up-with-domestic-drone-boom/#axzz2nsJOYVed&quot; rel=&quot;nofollow&quot;&gt;U.S. colleges begin offering more drone piloting programs to keep up with domestic drone boom&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://abclocal.go.com/kabc/story?id=9085952&quot; rel=&quot;nofollow&quot;&gt;California bills tackle drones, personal privacy&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.cbsnews.com/news/aviation-schools-prepare-for-boom-in-demand-for-drone-pilots/&quot; rel=&quot;nofollow&quot;&gt;Aviation schools prepare for boom in demand for drone pilots&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="117" LastEditorUserId="69" LastEditDate="2013-12-27T01:40:12.027" LastActivityDate="2014-04-07T02:13:33.400" Title="What licenses and/or training should one obtain to be able to fly a drone in California?" Tags="&lt;faa-regulations&gt;&lt;flight-school&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="146" PostTypeId="2" ParentId="115" CreationDate="2013-12-19T01:03:11.927" Score="3" Body="&lt;p&gt;&lt;em&gt;I originally posted this simply as a comment, but I suppose it's more of a partial answer.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I researched this about six months ago and found that, in the US, 6 seconds was the standard for a TRACON, and 12 seconds for an ARTCC - allowing them to see about a 60nmi and 120nmi radius, respectively. I don't have sources off-hand, but if I come across them, I'll post them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure about the accuracy, but when it's a human looking at a screen, discrepancies of even tens of feet is probably not particularly meaningful.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-19T01:03:11.927" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="147" PostTypeId="5" CreationDate="2013-12-19T01:47:14.417" Score="0" Body="&lt;p&gt;When the question is pertinent to flight at velocities exceeding the velocity of sound, apply this tag. A slightly more detailed introduction on supersonic flight may be perused on &lt;a href=&quot;http://en.wikipedia.org/wiki/Supersonic_aircraft&quot; rel=&quot;nofollow&quot;&gt;wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="83" LastEditorUserId="83" LastEditDate="2013-12-22T18:33:45.820" LastActivityDate="2013-12-22T18:33:45.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="148" PostTypeId="4" CreationDate="2013-12-19T01:47:14.417" Score="0" Body="Use for questions relating to flight at speeds greater than sound and related effects from doing so." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-30T00:41:20.013" LastActivityDate="2014-01-30T00:41:20.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="149" PostTypeId="1" AcceptedAnswerId="2698" CreationDate="2013-12-19T01:55:35.453" Score="52" ViewCount="58521" Body="&lt;p&gt;What are the main differences in flying a Boeing vs an Airbus aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ignoring cosmetics, e.g. nose/window shape (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1436/how-can-i-tell-apart-an-airbus-from-a-boeing&quot;&gt;How can I tell apart an Airbus from a Boeing?&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-05-22T00:00:44.547" Title="What are the main differences piloting Boeing vs. Airbus aircraft?" Tags="&lt;airbus&gt;&lt;boeing&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="150" PostTypeId="2" ParentId="149" CreationDate="2013-12-19T02:00:57.530" Score="27" Body="&lt;p&gt;Boeing aircraft primarily feature a traditional &quot;yoke&quot; system, which allows pilots to directly control the plane:&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uRwL6.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast, Airbus aircraft use a &quot;fly-by-wire&quot; system via a joystick which transmits electrical signals to control the plane:&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BseuC.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Airbus aircraft limit pilots' capabilities in situations that require extreme action to be taken; the computer may prevent the pilot from pushing the plane past its safe ranges, which could be necessary in case of an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing aircraft leave ultimate control mostly to the pilot.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2013-12-19T02:29:50.823" LastActivityDate="2013-12-19T02:29:50.823" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="151" PostTypeId="2" ParentId="119" CreationDate="2013-12-19T02:51:59.740" Score="17" Body="&lt;p&gt;There are of course a lot of tiny changes that Boeing would have done to the aircraft that most of us wouldn't notice, but for brevity I've just included the major changes between the 737NG series and the upcoming 737MAX.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The CFM LEAP-1B engine replaces the current CFM56 engines. Some of the significant improvements in fuel efficiency (15% savings minus drag from larger engine touted by CFM) come from a much higher bypass ratio (from 5.3:1 to approximately 9:1) and materials that can tolerate higher temperatures. Chevrons (saw-toothed tips at the end of the nacelle) have also been included to reduce engine noise on takeoff.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The engine change required changes to the nose landing gear to allow enough clearance from the ground, extending the nose gear by about 8 inches (20cm) and modifying the nose gear bay to allow it to fit into the existing space.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The AT (Advanced Technology) winglets replace the 737NG's blended winglets. The AT winglet incorporates two portions, done to reduce the weight required (compared to a larger blended wingtip) while still reducing block fuel burn by about 1.5%.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fly-by-wire spoiler system reduces the need for long cabling between the cockpit and the spoiler hydraulic actuators, saving weight, reducing stopping distance by quicker actuation and increasing the accuracy of the controls.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Redesigned tailcone and modifications to elevator to improve aerodynamics, removing the requirement for vortex generators (VGs), which improves predictability and control by making the air turbulent, but as a result increasing drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2013-12-24T05:14:54.470" LastActivityDate="2013-12-24T05:14:54.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="152" PostTypeId="2" ParentId="107" CreationDate="2013-12-19T03:02:34.550" Score="9" Body="&lt;p&gt;They are different modes that control aircraft pitch in different ways, and as a pilot you select what you want based on your current requirements.  Note that the modes even behave differently depending on the aircraft / autopilot, so referring to the actual aircraft/autopilot documentation is essential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many autopilots don't even have a Flight Level Change mode, but instead have an Indicated Airspeed (IAS) mode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autopilot modes like these are typically &quot;dumb&quot; and just do what they are told, without taking anything else into consideration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of which mode that is used, remember that it is the pilot responsibility to monitor the aircraft and to make sure that it is doing what they want it to do!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Indicated Airspeed / Flight Level Change&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This mode usually adjusts the pitch of the aircraft in order to maintain a specific airspeed.  In simple systems, the only inputs that are used are airspeed and aircraft pitch.&lt;/li&gt;&#xA;&lt;li&gt;You usually control the vertical speed of the aircraft by making power adjustments:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;By reducing power, your vertical speed will decrease.&lt;/li&gt;&#xA;&lt;li&gt;By increasing power, your vertical speed will increase.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In some systems your actual altitude is compared to the selected target altitude and a minimum climb or descent is maintained even if the airspeed can't be maintained.&lt;/li&gt;&#xA;&lt;li&gt;In some systems the aircraft altitude is used to change the behavior (for instance, in one aircraft that I have flown, if you are below 8,000 ft MSL and hit FLC, it will descend at 1,000 FPM but if you are above 8,000 feet it specifies a 250 KT IAS hold).&lt;/li&gt;&#xA;&lt;li&gt;In some systems, the pitch is adjusted to maintain a specific climb/descent schedule which automatically changes based on altitude.  For instance, a descent schedule might be Mach 0.80 until 29,000 ft., 350 KIAS until 10,000 ft. and 250 KIAS below 10,000 ft.&lt;/li&gt;&#xA;&lt;li&gt;Another aircraft that I have flown in the past even had two climb schedules. You could toggle between the &quot;normal&quot; climb and the &quot;high speed&quot; climb by hitting the FLC button more than once.&lt;/li&gt;&#xA;&lt;li&gt;A lot of autopilots (especially older ones) tend to oscillate around the target airspeed and constantly pitch up and down while trying to fly a specific airspeed.  For this reason (keeping in mind that passenger comfort could be an issue) many people avoid speed modes, especially at higher altitudes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Vertical Speed&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This mode usually adjusts the pitch of the aircraft in order to maintain a specific vertical speed.  Again, it is usually a &quot;dumb&quot; mode and doesn't look at anything but vertical speed and aircraft pitch.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2017-12-10T20:06:14.683" LastActivityDate="2017-12-10T20:06:14.683" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="153" PostTypeId="1" AcceptedAnswerId="162" CreationDate="2013-12-19T03:29:13.413" Score="19" ViewCount="10952" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.13.9.3.32&quot;&gt;FAR Part 91, Appendix G, Section 2&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) &lt;em&gt;Altitude-keeping equipment: All aircraft.&lt;/em&gt; To approve an aircraft&#xA;  group or a nongroup aircraft, the Administrator must find that the&#xA;  aircraft meets the following requirements:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;code&gt;&lt;/code&gt; &lt;code&gt;&lt;/code&gt;(2) The aircraft must be equipped with at least one automatic altitude&#xA;  control system that controls the aircraft altitude&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that it does &lt;strong&gt;not&lt;/strong&gt; say that it must be engaged, or even operative.  Simply &quot;equipped&quot;, and also that this is to &lt;strong&gt;approve&lt;/strong&gt; an aircraft for RVSM.  From what I can find, there is no operational requirement for the autopilot to actually be working or engaged.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that my MEL allows me to defer the autopilot and still fly, can I fly in RVSM airspace?  Some people however say that if you are in RVSM airspace that the autopilot must be &lt;strong&gt;working&lt;/strong&gt; and &lt;strong&gt;engaged&lt;/strong&gt;.  Right or wrong?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-24T01:08:51.510" LastActivityDate="2015-03-24T20:21:44.970" Title="Is it legal to fly in RVSM airspace with an inoperative autopilot?" Tags="&lt;faa-regulations&gt;&lt;autopilot&gt;&lt;airspace&gt;&lt;rvsm&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="154" PostTypeId="1" AcceptedAnswerId="166" CreationDate="2013-12-19T03:41:20.290" Score="9" ViewCount="3926" Body="&lt;p&gt;Does time logged in these foreign-registered aircraft (cross country, etc) count towards US certificates or ratings? Or is it flight experience that should be excluded from an 8710?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2013-12-30T03:39:42.303" LastActivityDate="2020-10-29T19:22:24.667" Title="Can time logged in foreign aircraft be applied towards an FAA certificate or rating?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;far-61&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="155" PostTypeId="1" AcceptedAnswerId="156" CreationDate="2013-12-19T04:09:48.380" Score="8" ViewCount="291" Body="&lt;p&gt;I know that under FAR Part 135, specific approval is required for an RNAV SID/STAR (given via an OpSpec), but what about Part 91?  Does the aircraft/pilot have to be approved, and if so how is the approval obtained?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-19T17:53:09.993" Title="Is FAA approval required in order to fly an RNAV SID/STAR for a private aircraft operated under FAR Part 91?" Tags="&lt;far-91&gt;&lt;sid-star&gt;&lt;faa-approval&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="156" PostTypeId="2" ParentId="155" CreationDate="2013-12-19T04:43:06.297" Score="8" Body="&lt;p&gt;The best answer I can give is &lt;strong&gt;generally, no.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In relatively few cases – for aircraft &lt;strong&gt;operated under Part 91 Subpart K&lt;/strong&gt;, which applies to fractional ownership like Netjets – the operator must possess an &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N%208900.176.pdf&quot;&gt;Mspec&lt;/a&gt;, which would be applied for at the local FSDO. I'm not sure what that process looks like, but &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs800/afs820/part91k_oper/&quot;&gt;the FAA's Commercial Operations Branch has some good information on that front&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For all other Part 91 operations&lt;/strong&gt; the aircraft simply needs to be appropriately equipped. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-19T17:53:09.993" LastActivityDate="2013-12-19T17:53:09.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="157" PostTypeId="1" CreationDate="2013-12-19T04:50:18.267" Score="12" ViewCount="566" Body="&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=EeOQElvfnpE&quot; rel=&quot;noreferrer&quot;&gt;John Ninomiya&lt;/a&gt; discusses his experience with developing this new style of ballooning on &lt;a href=&quot;http://www.clusterballoon.org/&quot; rel=&quot;noreferrer&quot;&gt;his Cluster Ballooning website.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the site's links are now broken, but on there he formerly attested that he was granted a pilots' license by the FAA for this style of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember the wording clearly suggesting that this license was different than other flight license. Does anyone know how it did, or could have, differed? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Any other relevant &lt;a href=&quot;http://en.wikipedia.org/wiki/Cluster_ballooning&quot; rel=&quot;noreferrer&quot;&gt;history about cluster ballooning&lt;/a&gt; is also appreciated. &lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="1467" LastEditDate="2016-05-25T10:36:56.240" LastActivityDate="2016-05-25T10:36:56.240" Title="How does a pilots license of cluster ballooning differ from other ballooning or unpowered flight?" Tags="&lt;pilot-certification&gt;&lt;unpowered&gt;&lt;lighter-than-air&gt;&lt;balloon&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="158" PostTypeId="1" AcceptedAnswerId="236" CreationDate="2013-12-19T04:56:52.807" Score="17" ViewCount="3584" Body="&lt;p&gt;I have seen &lt;a href=&quot;http://www.rockymountainhotair.com/propellers.htm&quot;&gt;fans like these&lt;/a&gt; for use in ballooning and glider propulsion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does adding one of these change the definition of the flight vehicle?  e.g. is it No longer a balloon, but now an aircraft?  Does only the flight elevation and proximity to a controlled airspace matter — or does the capacity of the craft have an impact?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose another dimension of this question regards if licensure changes in such case.&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="1467" LastEditDate="2016-05-25T10:37:06.583" LastActivityDate="2017-08-18T23:54:49.183" Title="Does adding a motorized fan to a hot air balloon change its class as an aircraft?" Tags="&lt;faa-regulations&gt;&lt;single-engine&gt;&lt;lighter-than-air&gt;&lt;balloon&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="159" PostTypeId="1" AcceptedAnswerId="886" CreationDate="2013-12-19T05:39:51.600" Score="15" ViewCount="23565" Body="&lt;p&gt;I've heard several terms referring to air traffic control procedures that restrict movement for a certain period of time: &lt;em&gt;ground stop&lt;/em&gt;, &lt;em&gt;ground delay&lt;/em&gt;, and &lt;em&gt;gate hold&lt;/em&gt; (plus others I'm sure I'm forgetting at the moment). How exactly does each of these procedures work? And do they affect arrivals, departures, or both?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="14957" LastEditDate="2021-01-13T10:17:53.707" LastActivityDate="2021-01-13T10:17:53.707" Title="What are the differences between &quot;ground stop&quot;, &quot;ground delay&quot;, and &quot;gate hold&quot;?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="160" PostTypeId="1" CreationDate="2013-12-19T06:11:20.090" Score="29" ViewCount="9537" Body="&lt;p&gt;I know that an ILS transmits not only the correct glideslope but also signals that can be interpreted as a false glide path. But I'm not familiar with the details of these erroneous indications. What causes &quot;side lobe&quot; or &quot;mirror&quot; false glideslopes? How many are there, where are they located, and what sensing do they cause in the aircraft? What is the typical behavior of a glideslope signal outside its usable range, or is it completely unpredictable?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="22726" LastEditDate="2019-08-31T00:47:50.117" LastActivityDate="2019-08-31T00:47:50.117" Title="What is the behavior of false glideslope signals?" Tags="&lt;ils&gt;&lt;glideslope&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="161" PostTypeId="2" ParentId="153" CreationDate="2013-12-19T07:39:15.413" Score="3" Body="&lt;p&gt;For RVSM, the autopilot (and altimeter) has to be operable, certified for maintaining a tight altitude tolerance, and maintained in an approved RVSM maintenance schedule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=4d278bf784f2b21983a0a2ab34f92b14&amp;amp;node=14:2.0.1.3.10&amp;amp;rgn=div5#14:2.0.1.3.10.13.9.3.32&quot; rel=&quot;nofollow&quot;&gt;FAA Part 91, appendix G, Section 2.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event the autopilot fails at RVSM altitudes, the pilot shall contact ATC and state &quot;Unable RVSM Due Equipment&quot;. ATC will provide non-RVSM separation and/or clear the aircraft out of RVSM airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0406.html#2wsW211a5mweb&quot; rel=&quot;nofollow&quot;&gt;AIM 4-6-8&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-19T23:53:43.130" LastActivityDate="2013-12-19T23:53:43.130" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="162" PostTypeId="2" ParentId="153" CreationDate="2013-12-19T10:02:09.867" Score="14" Body="&lt;p&gt;About whether or not you can fly with an inoperative autopilot, take a look at §91.180:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;§91.180   Operations within airspace designated as Reduced Vertical Separation Minimum airspace.&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraph (b) of this section, no person may&#xA;  operate a civil aircraft in airspace designated as Reduced Vertical&#xA;  Separation Minimum (RVSM) airspace unless:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The operator and &lt;strong&gt;the operator's aircraft comply with the minimum&#xA;  standards of appendix G of this part&lt;/strong&gt;; and&lt;/li&gt;&#xA;  &lt;li&gt;The operator is authorized by the Administrator or the country of&#xA;  registry to conduct such operations.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(b) The Administrator may authorize a deviation from the requirements&#xA;  of this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You also can't &lt;em&gt;say&lt;/em&gt; that your aircraft is allowed to operate in RVSM airspace:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Section 4. RVSM Operations&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Each person requesting a clearance to operate within RVSM airspace&#xA;  shall correctly annotate the flight plan filed with air traffic&#xA;  control with the status of the operator and aircraft with regard to&#xA;  RVSM approval. Each operator shall verify RVSM applicability for the&#xA;  flight planned route through the appropriate flight planning&#xA;  information sources.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) &lt;strong&gt;No person may show, on the flight plan filed with air traffic&#xA;  control, an operator or aircraft as approved for RVSM operations, or&#xA;  operate on a route or in an area where RVSM approval is required,&#xA;  unless:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The operator is authorized by the Administrator to perform such&#xA;  operations; and&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;&lt;strong&gt;The aircraft has been approved and complies with the requirements&#xA;  of Section 2 of this appendix.&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If it's not operational, the aircraft no longer qualities for RVSM, and therefore must be provided with 2000 feet vertical separation (each way) between other aircraft. Alternatively, ATC can refuse entry into RVSM airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding having the autopilot engaged, &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2091-85.pdf&quot;&gt;Appendix 4 of AC 91-85&lt;/a&gt;, Section &quot;5. In-flight Procedures&quot; states: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;e. An automatic altitude-control system should be operative and engaged during level cruise, except when circumstances such as the need to retrim the aircraft or turbulence require disengagement. In any event, adherence to cruise altitude should be done by reference to one of the two primary altimeters; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="72" LastEditorUserId="3504" LastEditDate="2014-12-08T23:44:04.267" LastActivityDate="2014-12-08T23:44:04.267" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="163" PostTypeId="1" AcceptedAnswerId="173" CreationDate="2013-12-19T11:14:29.583" Score="1" ViewCount="3190" Body="&lt;p&gt;During an emergency solely related to aviation (ie not a medical situation), suppose that some airline passenger believes that he/she can help in the cockpit. Since the cockpit door is locked for security, how can he/she volunteer their services and enter the cockpit to try to help? I am guessing that someone with minimal flying experience (such as an amateur gamer of Microsoft Flight Simulator) can help. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question presumes the ability of airline passengers to help. Here is a real-life example: According to the &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Mayday_episodes#Season_12_.282012.29&quot; rel=&quot;nofollow&quot;&gt;Mayday episode&lt;/a&gt; on Air France Flight 447, while attempting to recover from a stall, the first officer pushed his yoke up (wrongly), while the reserve first officer pushed his yoke down (correctly).  This opposition in pushing nullified each other and the plane continued its fall in its stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain was out of the cockpit at the start of the stall. He returned afterwards (I don't recall exactly when), spent some critical time surveying the control panel, but didn't apprehend the problem in time. Might a passenger have helped to perceive the problem (without spending time examining the instruments)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please feel free to edit this post; I'm not an expert on aviation. &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="128" LastEditDate="2015-09-04T00:11:15.333" LastActivityDate="2015-09-04T00:11:15.333" Title="How can passengers help in the cockpit in an aviational emergency?" Tags="&lt;emergency&gt;&lt;passenger&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ClosedDate="2013-12-20T22:29:02.307" ContentLicense="CC BY-SA 3.0" />
  <row Id="164" PostTypeId="1" AcceptedAnswerId="165" CreationDate="2013-12-19T12:19:19.890" Score="25" ViewCount="83508" Body="&lt;p&gt;Why does an airplane need trim, and what does it do during the flight? Does an autopilot adjust the trim automatically?&lt;/p&gt;&#xA;" OwnerUserId="70" LastEditorUserId="1467" LastEditDate="2016-02-22T18:25:22.837" LastActivityDate="2018-01-15T11:16:38.517" Title="What does the term &quot;trimming&quot; most commonly mean in aviation?" Tags="&lt;flight-controls&gt;&lt;navigation&gt;&lt;flight-instruments&gt;&lt;terminology&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="165" PostTypeId="2" ParentId="164" CreationDate="2013-12-19T12:59:15.883" Score="15" Body="&lt;p&gt;The purpose of trimming is to free the pilot from having to exert a constant pressure on the controls. This is often used to maintain straight and level flight, however trimming can also be used at any phase of flight - for example to maintain a constant rate of climb or descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most basic form, as found on most light aircraft is elevator trim. Usually operated by a wheel, it moves the elevator up or down by a small amount in the same sense as the yoke (back to go up, forward to go down). This can be used to settle the aircraft into straight flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another form of trim is rudder trim. Often found in larger light aircraft and twin-engined aircraft it can be used to adjust for a crosswind to keep the aircraft flying straight. On multi-engine aircraft it can also be used to trim out the differential thrust caused by one engine failing.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="13197" LastEditDate="2016-02-22T17:56:50.010" LastActivityDate="2016-02-22T17:56:50.010" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="166" PostTypeId="2" ParentId="154" CreationDate="2013-12-19T14:03:04.400" Score="9" Body="&lt;p&gt;Yes, it counts: the FAA doesn't care where flying hours are accumulated provided that the US written and/or practical test requirements are met. I learned to fly in South Africa then applied for an unrestricted FAA license (i.e. not a foreign based license). The FSDO told me that I could count all my time in SA (cross-countries, night flights etc.) towards the FAA license requirements, but I would still have to pass the FAA written and practical tests like any other student pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One practical issue in this situation is that hours may be logged slightly differently in different countries, by regulation or simply by local practice. The two examples I encountered were that PIC time is (was?) defined differently in SA and the US, and the number of landings is not relevant in SA for currency so no one logs them.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-19T14:03:04.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="167" PostTypeId="1" AcceptedAnswerId="31560" CreationDate="2013-12-19T14:16:05.123" Score="12" ViewCount="3226" Body="&lt;p&gt;As a private pilot, I am familiar with tower, ground, approach and departure control, but I am aware that there are other entities like clearance, pushback and center. If I were flying a commercial airliner, what is a complete, ordered list of entities (and a brief description of roles) I might talk with over a flight between two class B airports?&lt;/p&gt;&#xA;" OwnerUserId="26" LastEditorUserId="11136" LastEditDate="2016-09-15T15:27:19.010" LastActivityDate="2016-09-16T14:37:00.090" Title="What ATC entities does a commercial airliner communicate with?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="168" PostTypeId="2" ParentId="164" CreationDate="2013-12-19T14:21:37.080" Score="17" Body="&lt;p&gt;In short: trimming neutralizes the force required to keep control surfaces in a specific position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most (if not all) aircraft have some sort of elevator trim control. For example, when the pilot has to keep pulling back on the yoke/stick during a climb, trimming &quot;nose-up&quot; will neutralize that force. The elevator will then remain in the same position without any force required on the part of the pilot. Trimming is usually done by means of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Trim_tab&quot; rel=&quot;noreferrer&quot; title=&quot;Trim tab&quot;&gt;Trim tab&lt;/a&gt; on the control surface and is controlled by a trim wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elevator trimming is used:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;During climbs: to maintain a constant air speed and rate of climb&lt;/li&gt;&#xA;&lt;li&gt;During descents: to maintain a constant air speed and glide path&lt;/li&gt;&#xA;&lt;li&gt;During level flight: to maintain altitude and speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Although elevator trim is the most common, trimming can also be done on rudder (quite common) and ailerons (only on larger aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rudder trim is used to maintain coordinated flight without rudder input by the pilot. Many single engine planes with powerful engines require rudder trim to offset the &quot;left-turning tendency&quot; caused by P-factor and propellor wash hitting the rudder. Aircraft without adjustable rudder trim will usually have a fixed trim tab on the rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most autopilots will control the elevator trim wheel because the servos controlling the elevator could easily be overpowered by the required force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's important to note that in most cases (especially on small airplanes) trimming doesn't actually &lt;strong&gt;move&lt;/strong&gt; the control surfaces. It changes the force required to deflect the control surfaces. Although there are many types of trimming devices, the common &lt;strong&gt;trim tab&lt;/strong&gt; makes the airflow do all the work. The trim tab causes the airflow to push the control surface in a specific position. On larger aircraft with hydraulically operated control surfaces, trim tabs are less common (see also &lt;a href=&quot;https://aviation.stackexchange.com/questions/1231/is-trimming-aircraft-to-relieve-pilot-of-applying-force-on-control-stick-pedal-s/1235#1235&quot;&gt;this answer to another question&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-01-27T17:03:34.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="169" PostTypeId="2" ParentId="164" CreationDate="2013-12-19T14:29:08.500" Score="3" Body="&lt;p&gt;Trimming is changing the stability of an aircraft in such a way that when no control inputs are given, the aircraft maintains its attitude and speed. It allows the pilot to release the control input without the aircraft deviating from the intended path. In general the aircraft is trimmed for straight and level flight, but it can also be trimmed for descent or even for turns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various ways in which an aircraft can be trimmed. &#xA;Trimming most commonly refers to elevator trim. This involves changing the angle of incidence of a trim tab on the elevator in such a way that when the control column is released the aircraft does not pitch up or down by itself. In large aircraft, the angle of whole horizontal stabilizer can be changed to trim the pitch tendency of the aircraft. &#xA;Aircraft that have a fuel tank in the tail can move the centre of gravity by transferring fuel between forward and aft fuel tanks. Use of CG trim not only affects the pitch tendency of the aircraft but also reduces the fuel burn since less aerodynamic forces are needed to balance the aircraft, thereby reducing the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other forms of trim are aileron trim and rudder trim. These are used to nullify  any asymmetric characteristics of the aircraft. These characteristics can be caused for example due effects of propeller wash, mechanical deformation of the aircraft (or poor manufacturing tolerances) or engine out situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On most larger aircraft the autopilot uses elevator trim or horizontal stabilizer trim to control the aircraft in pitch in addition to elevator control. For turning, ailerons and rudder are used, the asymmetric trim is not used by the autopilot. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2013-12-19T14:29:08.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="170" PostTypeId="1" AcceptedAnswerId="1332" CreationDate="2013-12-19T15:23:38.187" Score="32" ViewCount="5903" Body="&lt;p&gt;As a passenger with a keen interest in aviation, I'd like to think I'd be eagle-eyed enough to spot a problem that the pilots mightn't be able to see, from where they're sitting (for example, an engine sputtering or ice on the wings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What things can we look out for, sat in the cabin, that might ultimately save a plane?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="72" LastEditDate="2014-01-17T08:11:08.120" LastActivityDate="2020-03-10T15:08:22.607" Title="What things can a passenger look out for, to indicate an emergency?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;emergency&gt;" AnswerCount="9" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="171" PostTypeId="2" ParentId="140" CreationDate="2013-12-19T15:32:21.440" Score="11" Body="&lt;p&gt;This &lt;a href=&quot;http://www.youtube.com/watch?v=iCWBQsjqGNk&quot;&gt;HD video&lt;/a&gt; of an A320 landing in Chicago shows that the ailerons move all the time during the approach, although the excitations are very limited from the moment the final flaps are selected. It seems there is some kind of limiting functions activated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus has various versions of the aileron and spoiler control system on the A320 family. It is important to note that all these control surfaces are used together to control roll, yaw and alleviate gust loading on the wing. On the short field kit, the ailerons will move upwards on both sides to assist in steeper descent. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is very common to use spoilers for augmented roll control during low speeds, most big jets use it. It is sometimes observed that spoilers deploy partially during takeoff under strong crosswind conditions. Here is an &lt;a href=&quot;http://www.youtube.com/watch?v=i9IhQxmt08U&quot;&gt;example of a B767&lt;/a&gt; that has spoilers deflected during most of the take-off roll.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2013-12-19T15:32:21.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="172" PostTypeId="2" ParentId="170" CreationDate="2013-12-19T15:38:46.870" Score="20" Body="&lt;p&gt;Interestingly, the reason why many airlines require window blinds to be raised for take-off and landing is specifically due to the extra visibility it affords passengers and cabin crew in spotting any particular problems for which the pilot and flight crew may not have very good visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skeptics.stackexchange.com/questions/8849/why-do-we-open-the-window-shades-during-landing-and-take-off/8853#8853&quot;&gt;Skeptics: Why do we open the window shades during landing and take-off?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Crew and passengers can easily see any external damage, fire or smoke indicating a problem and perhaps bringing it to the attention of flight crew quicker.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There were also reports that it was a passenger who noticed a engine cowling door having been left open after maintenance on a &lt;a href=&quot;http://www.telegraph.co.uk/news/aviation/10092099/Engine-doors-on-stricken-BA-flight-left-open-official-report-finds.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;recent British Airways incident flight&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vtM11.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;However, although the pilot and flight crew may not be able to see these things directly, you should rest assured that their instrumentation should bring to their attention any engine problems. An engine malfunction or fire would almost certainly become apparent to the flight crew by virtue of warning indications, and loss of power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, if you ever have cause for concern as a passenger you should bring it to the attention of cabin crew. They will, one would hope, have the skill &amp;amp; experience to know whether to bring it to the attention of the flight crew!&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2017-04-13T12:46:45.343" LastActivityDate="2014-03-19T08:04:50.450" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="173" PostTypeId="2" ParentId="163" CreationDate="2013-12-19T16:06:15.493" Score="41" Body="&lt;p&gt;The short answer is to sit down, shut up, and stay the heck out of the way.  That's what I would do.  If you can quietly help the one or two people sitting next to you do the same, you're doing your part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seriously, the last thing the flight crew needs in a flight emergency is extra distractions from passengers - especially those without directly relevant experience (e.g., an off duty airline pilot commuting home).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less seriously, it's a common fantasy/daydream among private pilots that some weird emergency results in them taking over the controls.  Pre-9/11, I had the opportunity to try landing a 747 in one of the airline's full motion sims.  (I have zero relevant experience in flying something that big).  On the first landing, all the big pieces came to a stop on or near airport property.  On the second attempt, I think I got most of the pieces to come to a stop on or near the runway.  I doubt many people would have survived either attempt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My plan if this would ever happen in real life is to get on the radio &amp;amp; demand that an instructor tell me which buttons on the autopilot to push.  If successful, I'd then go buy a lottery ticket before the crazy luck wears off :-)&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2013-12-19T16:06:15.493" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="174" PostTypeId="2" ParentId="129" CreationDate="2013-12-19T17:03:16.607" Score="1" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You need to create lift, so (as one person mentioned) you can do this by towing - e.g. getting pulled by a car.  Then (if the air is right) you'll be able to gain enough altitude to sustain flight among prevalent currents.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You could presumably run and produce the same effect, if you had the right wind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;a small fan + motor could do similar - but now you are no longer in the range of powerless flight&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;you could try to fly a kite or small chute, to given you additional lift and aid powerless take-ff&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="57" LastActivityDate="2013-12-19T17:03:16.607" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="175" PostTypeId="1" AcceptedAnswerId="179" CreationDate="2013-12-19T17:07:42.790" Score="18" ViewCount="381" Body="&lt;p&gt;I'm currently saving money for a plane and training, and the expectations are that I won't have the money for full ownership of much else north of a Cessna 150.  I'm investigating partial ownership instead, and I've read that forming a company/partnership to own the plane is better than each member of the group just pitching in out of pocket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any drawbacks to using this method for plane ownership?&lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="1696" LastEditDate="2015-10-07T14:57:58.420" LastActivityDate="2015-10-07T14:57:58.420" Title="Partial ownership: are there any pitfalls to owning the plane through a shell company?" Tags="&lt;aircraft-ownership&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="176" PostTypeId="2" ParentId="175" CreationDate="2013-12-19T17:29:38.880" Score="9" Body="&lt;p&gt;I was in a club like that.  The big advantage (for us) was that we didn't have to pay sales tax when buying or selling a share.  The club owns the plane (&amp;amp; the tools &amp;amp; the engine reserve, etc) and you buy shares in the club.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We had to have an annual meeting, officers, &amp;amp; file with the state.  It wasn't a big deal.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2013-12-19T17:29:38.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="177" PostTypeId="1" AcceptedAnswerId="181" CreationDate="2013-12-19T18:26:26.627" Score="29" ViewCount="38555" Body="&lt;p&gt;What are the rules with regards to landing a float plane on a body of water?  Can I land anywhere (non-emergency, obviously) that would also accommodate the take-off?  If not, how do I determine which bodies of water would allow it and which would not? &lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="69" LastEditDate="2014-01-18T17:49:28.717" LastActivityDate="2018-10-24T03:24:35.863" Title="If I have a float plane, can I land on any body of water?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;seaplane&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="178" PostTypeId="2" ParentId="29" CreationDate="2013-12-19T18:26:52.393" Score="8" Body="&lt;p&gt;What you need is enough lift to remain in the air. For that, the maximum lift of your hang glider needs to exceed the total weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you know the total weight of the glider (you included), you can derive the theoretical minimum airspeed from the lift formula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L_{max}=\frac12{\rho}V^2C_{max}S$$&#xA;$$V_{min}=\sqrt{\frac{2W}{{\rho}C_{max}S}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$L$ = lift&lt;/li&gt;&#xA;&lt;li&gt;$\rho$ = air density&lt;/li&gt;&#xA;&lt;li&gt;$V$ = air speed&lt;/li&gt;&#xA;&lt;li&gt;$C_{max}$ = maximum lift coefficient&lt;/li&gt;&#xA;&lt;li&gt;$S$ = wing surface&lt;/li&gt;&#xA;&lt;li&gt;$W$ = weight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now you have to know your maximum lift coefficient. Suppose this is 1.2, and for safety and initial manoeuvring, let's add a margin of 40% to the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say your mass is 85 kg, and the glider has a mass of 35 kg. The total weight would be 120 kg &amp;mdash; that is about 1,177N weight, which for the sake of safety margin is increased to 1,650N.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll estimate the surface of the wing to be $16m^2$. Assume a normal day, the air density will be about $1.225kg/m^3$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Filling in the numbers is the formula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_{min}=\sqrt{\frac{2\times1650}{1.225\times1.2\times16}}\approx 12 \textrm{ m/s}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any wind speed you get you can subtract from this figure: what is left you have to achieve by pushing, running or diving.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-09T11:40:12.773" LastActivityDate="2015-05-09T11:40:12.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="179" PostTypeId="2" ParentId="175" CreationDate="2013-12-19T18:35:14.863" Score="18" Body="&lt;p&gt;The main thing to do is to realize why you're creating the corporation.  We created a 501(c)7 (in the US) corporation which is a tax-exempt organization and falls under &quot;social club.&quot;  We did this to limit our personal liability.  However, if you are creating the corporation to limit personal liability, you have to make sure to operate like a corporation - call each other &quot;co-owners&quot; instead of &quot;partners&quot; (there are legal ramifications to this, not just semantics).  People around the airport should know it's a co-owned plane by a corporation, not that it's &quot;your plane.&quot;  Basically if you want the liability protection of a corporation, you must act like one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Great book to read regarding the legal side of things is &quot;&lt;a href=&quot;http://amzn.com/1560277637&quot; rel=&quot;nofollow&quot;&gt;Practical Aviation Law&lt;/a&gt;&quot; by J. Scott Hamilton&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on how you set it up (we did a 501(c)7 tax exempt, and yes, you still have to file a tax return), how you use the airplane matters too.  For example, we can't earn money using the airplane (conducting flight instruction to non-co-owners, for example), due to the 501(c)7 status.  Under other corporate structures you can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I guess to actually answer your questions: There are some pitfalls, but I think they can be avoided.  Most group ownership things fail because of lack of communication and documentation, forming a corporation kind of forces you to spell out things explicitly and then all involved have no excuse for not knowing &quot;the rules.&quot; (You have to write up bylaws and have at least one annual meeting, which forces the communication aspect!)&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="97" LastEditDate="2015-05-03T04:04:45.127" LastActivityDate="2015-05-03T04:04:45.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="180" PostTypeId="2" ParentId="177" CreationDate="2013-12-19T18:42:32.097" Score="1" Body="&lt;p&gt;Drawing on some personal observations, many float-plane sites around Seattle are marked on maps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://skyvector.com/?ll=47.75514156211891,-122.2606417382991&amp;amp;chart=1&amp;amp;zoom=1&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Kenmore&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://skyvector.com/?ll=47.643077492900474,-122.33074788693787&amp;amp;chart=1&amp;amp;zoom=1&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Lake Union&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://skyvector.com/?ll=48.64265610046108,-122.85841165933282&amp;amp;chart=1&amp;amp;zoom=1&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Rosario&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I've also observed float planes taking off and landing at sites that are not appropriately marked on the map.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot cite regulations, but my eyeballs suggest that any safe place may be legally okay.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2013-12-19T18:42:32.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="181" PostTypeId="2" ParentId="177" CreationDate="2013-12-19T18:44:01.743" Score="16" Body="&lt;p&gt;It really depends on the state, though you can't land in National Parks (the National Park Service regulates that, not the FAA).  The FAA doesn't care where you land it, though if you ball it up due to poor choice of landing area then they'll have something to say.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some states don't really care where you land (like Oregon), others don't let you land anywhere (like New Jersey).  You should contact your state and get the regulations from them.&lt;/p&gt;&#xA;" OwnerUserId="66" LastEditorUserId="66" LastEditDate="2013-12-19T19:23:41.653" LastActivityDate="2013-12-19T19:23:41.653" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="182" PostTypeId="2" ParentId="170" CreationDate="2013-12-19T18:57:41.497" Score="45" Body="&lt;p&gt;Honestly, as a passenger, you're not really qualified to look for problems.  If you're a pilot qualified &lt;em&gt;and with experience&lt;/em&gt; in that type then you might see something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've had passengers tell my flight attendants that they saw flames coming out of a seam in the engine cowling.  It was actually a section of orange rubbery material that was sticking out and flapping in the breeze.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ice on the wings depends on the airplane too, you're often going to see some ice on the leading edges in icing conditions, and it's normal.  To know what's not normal, you have to have experience with that specific type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is actually one thing you could probably look for.  There are no airplanes that I know of that can safely take off with ice on the top of the wings (behind the leading edges).  That would be a legitimate thing to scream about; however, a pilot that would take off in such a case probably shouldn't be a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can certainly ask questions about things you see, but don't phrase it such that you think you found a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Window shades are requested to be open for take off and landing by some operators to allow the flight attendants to quickly assess the situation outside when directing an evacuation.  It has nothing to do with allowing passengers to look for problems.  Not all airlines have this policy either, it's somewhat uncommon, the first thing I do when I sit down at a window in the back is close the window, and it's rare that I'm asked to open it.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2013-12-19T18:57:41.497" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="183" PostTypeId="1" AcceptedAnswerId="227" CreationDate="2013-12-19T18:57:44.110" Score="28" ViewCount="8317" Body="&lt;p&gt;I own a PPL(A) license following JAR-FCL. Recently, this license has been exchanged for a European EASA license.&#xA;My training was on a motor glider (TMG), I do not have ratings for SEP, but TMG and Ultralight only.&#xA;In Germany I will have to fly a one hour test on an SEP to get the rating (plus about 5h for training).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do I have to do in the US to get the rating?&lt;/p&gt;&#xA;" OwnerUserId="133" LastEditorUserId="69" LastEditDate="2014-01-18T17:10:53.793" LastActivityDate="2014-07-29T19:44:57.647" Title="I have a European EASA license - what do I need to do to be allowed to fly in the US?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;far-61&gt;&lt;ppl&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="184" PostTypeId="1" AcceptedAnswerId="191" CreationDate="2013-12-19T18:58:48.983" Score="18" ViewCount="4184" Body="&lt;p&gt;In case of an emergency landing (non-fatal) on a road/highway or in a large field, what happens next?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Should police be contacted?&lt;/li&gt;&#xA;&lt;li&gt;Should aircraft owner and/or insurance be contacted?&lt;/li&gt;&#xA;&lt;li&gt;In case landing is on a road or highway, what should the pilot do?&lt;/li&gt;&#xA;&lt;li&gt;In case of landing on someone's personal property, what should one do?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="3504" LastEditDate="2015-01-20T15:05:30.610" LastActivityDate="2015-01-20T15:05:30.610" Title="After an emergency landing, what procedures should the pilot follow?" Tags="&lt;flight-planning&gt;&lt;emergency&gt;&lt;aircraft-failure&gt;&lt;landing&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="185" PostTypeId="2" ParentId="177" CreationDate="2013-12-19T19:02:51.663" Score="3" Body="&lt;p&gt;States with coastlines often manage this through a &quot;port authority&quot; association, &lt;a href=&quot;http://www.massport.com/&quot; rel=&quot;nofollow&quot;&gt;like Massachuesetts.&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes it is a joint association, like in the case of the &lt;a href=&quot;http://www.panynj.gov/&quot; rel=&quot;nofollow&quot;&gt;PA-NY-NJ Port Authority&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="57" LastActivityDate="2013-12-19T19:02:51.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="186" PostTypeId="5" CreationDate="2013-12-19T19:04:33.747" Score="0" Body="&lt;p&gt;Landing is when an aircraft touches down on the ground and is the final phase of flight. Landing techniques vary depending on the aircraft and the landing surface, but most landings in a fixed-wing aircraft include four stages: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Descent (or final approach): reducing speed, lining up with the runway and descending to just above the surface&lt;/li&gt;&#xA;&lt;li&gt;Flare (or roundout): lifting the nose of the aircraft just before touchdown to avoid landing nose first, and reducing speed further&lt;/li&gt;&#xA;&lt;li&gt;Touchdown: making contact with the ground&lt;/li&gt;&#xA;&lt;li&gt;Rollout: slowing the aircraft on the ground&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aircraft always land into the &lt;a href=&quot;/questions/tagged/wind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wind&amp;#39;&quot; rel=&quot;tag&quot;&gt;wind&lt;/a&gt;, if possible, because it reduces the aircraft's &lt;a href=&quot;/questions/tagged/groundspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;groundspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;groundspeed&lt;/a&gt; on touchdown; for instance, if an aircraft has an &lt;a href=&quot;/questions/tagged/airspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspeed&lt;/a&gt; of 80 knots on landing with a headwind of 20 knots, then the groundspeed at touchdown is reduced to 60 knots. A lower groundspeed results in a gentler, safer landing with less &lt;a href=&quot;/questions/tagged/braking&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;braking&amp;#39;&quot; rel=&quot;tag&quot;&gt;braking&lt;/a&gt; required, because the aircraft has less kinetic energy and momentum when it touches down.  In contrast, landing with a tailwind &lt;em&gt;increases&lt;/em&gt; the aircraft's groundspeed for a given airspeed; to use our earlier aircraft with an 80-knot airspeed at touchdown, a 20-knot tailwind would require the aircraft to touch down with a groundspeed of &lt;em&gt;100&lt;/em&gt; knots, putting much more stress on the brakes, hastening &lt;a href=&quot;/questions/tagged/tire&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tire&amp;#39;&quot; rel=&quot;tag&quot;&gt;tire&lt;/a&gt; wear, and increasing the amount of runway needed to stop safely (thus also increasing the risk of a &lt;a href=&quot;/questions/tagged/runway-overrun&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runway-overrun&amp;#39;&quot; rel=&quot;tag&quot;&gt;runway-overrun&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After touchdown, the pilot slows the aircraft during rollout to a speed where it can be safely steered on the ground (or water).  Wheel brakes, &lt;a href=&quot;/questions/tagged/spoilers&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spoilers&amp;#39;&quot; rel=&quot;tag&quot;&gt;spoilers&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/airbrakes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbrakes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbrakes&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/thrust-reverser&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust-reverser&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust-reverser&lt;/a&gt;s, and even &lt;a href=&quot;/questions/tagged/parachute&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;parachute&amp;#39;&quot; rel=&quot;tag&quot;&gt;parachute&lt;/a&gt;s can be used to help slow the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;/questions/tagged/helicopter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helicopter&amp;#39;&quot; rel=&quot;tag&quot;&gt;helicopter&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/stol&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stol&amp;#39;&quot; rel=&quot;tag&quot;&gt;stol&lt;/a&gt;/&lt;a href=&quot;/questions/tagged/vtol&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vtol&amp;#39;&quot; rel=&quot;tag&quot;&gt;vtol&lt;/a&gt; aircraft may use different landing techniques, and many aircraft require specific procedures for certain conditions such as short or contaminated (e.g. snow-covered) runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for all questions about landing techniques and procedures, legal regulations on landings, and so on. Questions about approaches - i.e. the maneuvering phase of flight before final approach - should usually be tagged &lt;a href=&quot;/questions/tagged/approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;approach&lt;/a&gt; instead.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Landing&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-08-08T05:45:43.307" LastActivityDate="2019-08-08T05:45:43.307" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="187" PostTypeId="4" CreationDate="2013-12-19T19:04:33.747" Score="0" Body="Landing is the final phase of flight, when an aircraft touches down on the runway or other surface." OwnerUserId="57" LastEditorUserId="6919" LastEditDate="2015-04-09T06:32:10.870" LastActivityDate="2015-04-09T06:32:10.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="188" PostTypeId="2" ParentId="184" CreationDate="2013-12-19T19:05:35.720" Score="8" Body="&lt;p&gt;You are talking explicitly about an emergency landing, not about an outlanding (yes, this word really seems to exist...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the answer that is valid in Europe:&#xA;In case of emergency, the federal office of aviation has to be informed. They will then check the conditions. If you start before their OK, it will be a criminal act.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it was a security landing, you will need to ask the owner of the land for permission and you'll need somebody who's watching while you take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no, you don't have to inform the police, but usually you will.&lt;/p&gt;&#xA;" OwnerUserId="133" LastActivityDate="2013-12-19T19:05:35.720" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="189" PostTypeId="2" ParentId="159" CreationDate="2013-12-19T21:04:30.767" Score="5" Body="&lt;p&gt;At least for the US, the specific terms you mentioned are defined in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;GROUND STOP (GS)- The GS is a process that requires aircraft that meet&#xA;a specific criteria to remain on the ground. The criteria may be&#xA;airport specific, airspace specific, or equipment specific; for&#xA;example, all departures to San Francisco, or all departures entering&#xA;Yorktown sector, or all Category I and II aircraft going to Charlotte.&#xA;GSs normally occur with little or no warning.&lt;/p&gt;&#xA;&lt;p&gt;GROUND DELAY PROGRAM (GDP)- A traffic management process administered&#xA;by the ATCSCC; when aircraft are held on the ground. The purpose of&#xA;the program is to support the TM mission and limit airborne holding.&#xA;It is a flexible program and may be implemented in various forms&#xA;depending upon the needs of the AT system. Ground delay programs&#xA;provide for equitable assignment of delays to all system users.&lt;/p&gt;&#xA;&lt;p&gt;GATE HOLD PROCEDURES- Procedures at selected airports to hold aircraft&#xA;at the gate or other ground location whenever departure delays exceed&#xA;or are anticipated to exceed 15 minutes. The sequence for departure&#xA;will be maintained in accordance with initial call-up unless modified&#xA;by flow control restrictions. Pilots should monitor the ground&#xA;control/clearance delivery frequency for engine start/taxi advisories&#xA;or new proposed start/taxi time if the delay changes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Wikipedia has some more information:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_stop&quot; rel=&quot;noreferrer&quot;&gt;Ground stop&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_delay_program&quot; rel=&quot;noreferrer&quot;&gt;Ground delay program&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;But I suspect that a really detailed explanation is probably only in the ATC manuals and procedures (and is probably far too long and complex to post here). I'm neither a commercial pilot nor a controller, though, so hopefully someone with more direct knowledge can comment.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-07T23:27:33.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="190" PostTypeId="1" AcceptedAnswerId="194" CreationDate="2013-12-19T21:31:32.360" Score="16" ViewCount="1869" Body="&lt;p&gt;When flying under Part 135, is it legal to takeoff knowing that you will exceed the allowable duty time due to an unplanned delay after the start of taxi?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ce76c8d77f2874ddda156e3e0c016e82&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot;&gt;135.267&lt;/a&gt;(d) says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each assignment under paragraph (b) of this section must provide&#xA;  for at least 10 consecutive hours of rest during the 24-hour period&#xA;  that precedes the planned completion time of the assignment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if the determining factor is the &lt;em&gt;planned completion time of the assignment&lt;/em&gt;, am I good if my passengers showed up late on an earlier leg, or if I have to wait at the runway for 30 minutes before I takeoff if it will cause me to exceed the limit?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2015-02-19T19:30:01.547" LastActivityDate="2015-02-19T19:30:01.547" Title="Do pilots have to consider unplanned delays for Part 135 duty time exceedance?" Tags="&lt;faa-regulations&gt;&lt;far-135&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="191" PostTypeId="2" ParentId="184" CreationDate="2013-12-19T22:01:23.427" Score="22" Body="&lt;p&gt;There seem to be two parts to your question. First, what practical steps can I take on the ground immediately after landing? Second, which authorities must be notified?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the first point, there are just too many scenarios to have a single answer but basically you should immediately check for injuries or damage to property and activate the emergency services if required. After that, secure the aircraft to prevent any further damage, call your insurance company and inform the aircraft owner and local property owner (as applicable). I'd also suggest giving your family a call rather than have them hear on TV news that you were &quot;in a crash landing&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more dramatic possibilities, of course: if you ditched or landed in a remote area or in extreme weather then actual survival could be your highest priority. But that's a topic for &lt;a href=&quot;https://outdoors.stackexchange.com/&quot;&gt;another site&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the second point, at least in the US it's possible that you don't have to notify anyone. If no one is hurt, nothing is damaged, and none of the incidents requiring immediate notification occurred (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7220e44ec883d713cc6836fce8d3d8e8&amp;amp;node=49:7.1.4.1.12.2.1.1&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;49 CFR 830.5&lt;/a&gt; and the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0706.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 7-6-2&lt;/a&gt;) then there's no legal requirement to inform anyone. The authorities in this case would be the NTSB, not the FAA, by the way. There's a more detailed discussion of these requirements &lt;a href=&quot;http://www.aerolegalservices.com/Articles/Aircraft%20Accident-Incident%20Reporting.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An additional concern that I know nothing about is liability and other legal issues. Getting legal advice - e.g. from your insurance company or AOPA - would probably be a good idea whatever the circumstances.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:48:01.717" LastActivityDate="2013-12-19T22:01:23.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="192" PostTypeId="2" ParentId="160" CreationDate="2013-12-19T23:59:09.780" Score="21" Body="&lt;p&gt;The glideslope system is an analog system, and as such, it's subject to aliasing, resonances, heterodyning, and eight other technical terms I pulled out of my ass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe a diagram will help:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.answers.com/topic/false-glide-slope&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/v5ap5.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.answers.com/topic/false-glide-slope&quot; rel=&quot;noreferrer&quot;&gt;false glide slopes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In plain English, above the &quot;real&quot; glideslope, there are false glide slopes caused by your equipment locking onto the wrong phase of the signals. If you lock onto the wrong lobe, it will still take you to the runway, but at a much higher rate of descent than you planned for. Maybe steeper than you can manage safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the correct lobe is the bottom-most one in the system (see diagram), you'll be ok as long as you intercept it from below. If you intercept from above, you could lock onto the wrong one, and then you're gonna have a Real Bad Day.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="40395" LastEditDate="2019-05-15T02:33:33.387" LastActivityDate="2019-05-15T02:33:33.387" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="193" PostTypeId="2" ParentId="126" CreationDate="2013-12-20T00:46:49.940" Score="6" Body="&lt;p&gt;When I arrive at an uncontrolled airport, and there's nobody there to tell me what everybody else is doing, I overfly the airport to get the lay of the land and to look at the wind sock. This should be SOP for everybody.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One glance at the wind sock will tell you which runway the winds favor. No math or diagrams required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should also be looking for a &lt;a href=&quot;http://www.groundinstructor.com/mod/page/view.php?id=1004&quot; rel=&quot;nofollow noreferrer&quot;&gt;tetrahedron&lt;/a&gt;. This will also give you information about the pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nominally, this is the authoritative answer about landing direction, but I've known airports where the tetrahedron was inoperative. If the wind is strong and the wind sock contradicts the tetrahedron, consider trusting the wind sock instead. Or better yet, consult the locals.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="87" LastEditDate="2019-01-22T22:35:11.797" LastActivityDate="2019-01-22T22:35:11.797" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="194" PostTypeId="2" ParentId="190" CreationDate="2013-12-20T01:02:43.467" Score="12" Body="&lt;p&gt;Note that if you operate under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2a7da0cbb5e764526dbddb044662e55c&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§135.267(b)&lt;/a&gt;, that there isn't any specific duty time definition -- there are only regulations concerning the maximum flight time and minimum rest time in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2a7da0cbb5e764526dbddb044662e55c&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§135.267(d)&lt;/a&gt; (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/533/what-is-the-legal-interpretation-of-rest-for-faa-part-135-operations&quot;&gt;this question&lt;/a&gt; for the definition of rest time). In &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc400/civil_penalty/casefile/view/1995/1995-8.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;a FAA Civil Penalty Order&lt;/a&gt;, it is noted that duty time is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;any time that is not a rest period.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you're operating under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2a7da0cbb5e764526dbddb044662e55c&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§135.267(c)&lt;/a&gt;, &quot;a regularly assigned duty period&quot; is also not defined, however, a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/berry%20-%20%282009%29%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;legal interpretation in 2009&lt;/a&gt; states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a pilot under a regularly assigned duty period &quot;comes to work and ... goes home at the same time every day&quot;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now the question is, whether late passengers or being held up by ATC would be considered as affecting &quot;the planned completion time of the assignment&quot;. The FAA has held in &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2013/masterson%20-%20%282013%29%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;prior legal interpretations&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;delays caused by late passenger or cargo arrivals, maintenance&#xA;  difficulties, and adverse weather are beyond the control of the&#xA;  certificate holder.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And in &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2012/kidd%20-%20%282012%29%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;another legal interpretation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;delays due to air traffic control, mechanical problems, or adverse&#xA;  weather could constitute circumstances that are beyond the control of&#xA;  the certificate holder.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, it is noted that these provisions only apply &lt;em&gt;if&lt;/em&gt; the original schedule was realistic. For example, if it is typical that ATC will place aircraft into a hold for 1 hour and this is not taken into account, this could be considered an &quot;unrealistic&quot; schedule for the purposes of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2a7da0cbb5e764526dbddb044662e55c&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§135.267&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that if no initial &quot;planned completion time of the assignment&quot; was calculated prior to accepting an assignment though, then &quot;being late&quot; may not be a legal defence if taken to court. In 1995, a case involving &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc400/civil_penalty/casefile/view/1995/1995-8.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Charter Airlines, Walker and Mort&lt;/a&gt; questioned whether it was a violation of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2a7da0cbb5e764526dbddb044662e55c&amp;amp;node=14:3.0.1.1.11.6.3.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§135.267(b) &amp;amp; §135.267(d)&lt;/a&gt; to accept a flight even when it was known that the cargo would be late to arrive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because it was found that there was no &quot;planned completion time of the assignment&quot;, they were on duty when waiting for the cargo (and therefore not &quot;free of all obligations&quot;) and they had accepted the assignment &lt;em&gt;after&lt;/em&gt; it was aware that the incoming cargo would be late, the FAA issued civil penalties amounting to \$10000 for Charter Airlines, and \$2000 each for Walker and Mort.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-04-23T12:24:48.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="195" PostTypeId="1" AcceptedAnswerId="196" CreationDate="2013-12-20T01:57:05.167" Score="12" ViewCount="839" Body="&lt;p&gt;On this approach plate, the holding pattern shown is depicted for a missed approach:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7XKsJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7XKsJ.png&quot; alt=&quot;Approach plate: PADU NDB-A RWY 30 CIRCLING&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in the notes, it says to&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Descend to 6000 in holding pattern.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;even though you should only climb to 4700 feet, according to the missed approach procedure:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Climb to 3000 via 166° bearing then climbing left turn to 4700 direct DUT NDB/DME and hold.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does the note actually mean (especially since it seems to be implying you would be &lt;em&gt;higher&lt;/em&gt; than 6000 on the missed approach procedure)?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="572" LastEditDate="2015-02-19T10:09:26.317" LastActivityDate="2015-02-19T10:09:26.317" Title="What is the correct holding altitude for the missed approach at Unalaska (PADU)?" Tags="&lt;approach&gt;&lt;iaps&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="196" PostTypeId="2" ParentId="195" CreationDate="2013-12-20T02:46:56.657" Score="7" Body="&lt;p&gt;That note actually refers to the holding pattern in general, not to the missed approach procedure. Your reading of the missed is correct.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Descend to 6000 in holding pattern.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Refers to descent from the MSA or any other enroute altitude. Before transitioning from enroute to the outbound initial segment (departing the IAF) the pilot must descend in the hold to 6000. Once leaving DUT outbound, descend as specified to 4700. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-20T05:26:48.713" LastActivityDate="2013-12-20T05:26:48.713" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="197" PostTypeId="2" ParentId="195" CreationDate="2013-12-20T05:23:50.247" Score="5" Body="&lt;p&gt;In this approach (and several others in Alaska) you may need to descend in a holding pattern from a higher assigned altitude to one that is used to begin the approach. For example, you might be assigned 10,000 ft. coming to Dutch Harbor from Cold Bay on G8. When you get to DUT, the initial approach fix, you would descend in the holding pattern from 10,000 to 6000, and continue to the procedure turn from there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Egid said, it does not affect the missed approach, in which you climb to 4,700 feet and hold at DUT.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-20T05:23:50.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="198" PostTypeId="1" AcceptedAnswerId="211" CreationDate="2013-12-20T05:44:04.003" Score="61" ViewCount="114255" Body="&lt;p&gt;Some people consider flying small planes very dangerous. Just how dangerous is it to fly in a light single-engine plane? For example, how does the fatality rate compare to driving a car, riding a motorcycle, etc.?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="97" LastEditDate="2014-01-13T02:06:29.213" LastActivityDate="2018-11-20T14:15:19.777" Title="How dangerous is flying in a single-engine plane?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;single-engine&gt;" AnswerCount="4" CommentCount="11" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="199" PostTypeId="1" CreationDate="2013-12-20T05:51:56.747" Score="14" ViewCount="6175" Body="&lt;p&gt;What equipment is required to fly a small plane across the Atlantic via Canada, Greenland, and Iceland? Is any additional training required beyond an ordinary pilot certificate? Can it be done in VFR flight?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-20T20:02:29.187" LastActivityDate="2014-10-27T13:42:21.593" Title="What is required for transatlantic flight in a private plane?" Tags="&lt;equipment&gt;&lt;visual-flight-rules&gt;&lt;transatlantic&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="200" PostTypeId="1" AcceptedAnswerId="206" CreationDate="2013-12-20T05:59:32.067" Score="16" ViewCount="10400" Body="&lt;p&gt;If you plan to fly on a cold morning and there is frost on the plane, what needs to be done?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you have to remove the frost from the windows? wings? tail? fuselage?&lt;br&gt;&#xA;How should you remove a thick layer of frost?&lt;br&gt;&#xA;Can you rub the frost until it's smooth and take off?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="64" LastEditDate="2014-01-10T16:29:22.697" LastActivityDate="2014-12-06T17:50:53.390" Title="How do you handle frost on a plane?" Tags="&lt;preflight&gt;&lt;icing&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="201" PostTypeId="1" AcceptedAnswerId="204" CreationDate="2013-12-20T06:02:49.770" Score="13" ViewCount="9583" Body="&lt;p&gt;What is a demonstrated crosswind component? Is it possible to land in a crosswind greater than the demonstrated crosswind component? Is it safe to?&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2021-03-12T05:19:42.830" Title="What is a demonstrated crosswind component?" Tags="&lt;crosswind&gt;&lt;aircraft-limitations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="202" PostTypeId="1" AcceptedAnswerId="218" CreationDate="2013-12-20T06:19:25.213" Score="17" ViewCount="2881" Body="&lt;p&gt;Is it true that it's legal to fly a plane over max gross weight in Alaska? If so, what are the rules?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="39" LastEditDate="2013-12-21T01:21:12.370" LastActivityDate="2013-12-21T17:31:01.127" Title="Is it legal to overload a plane in Alaska?" Tags="&lt;faa-regulations&gt;&lt;aircraft-limitations&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="203" PostTypeId="1" AcceptedAnswerId="208" CreationDate="2013-12-20T06:21:14.973" Score="22" ViewCount="10005" Body="&lt;p&gt;Is there a reason a pilot would takeoff downwind or land downwind? Is it legal to do this?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="14661" LastEditDate="2016-06-17T04:43:11.377" LastActivityDate="2017-04-21T12:27:28.770" Title="Do pilots ever intentionally takeoff or land downwind?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;wind&gt;&lt;takeoff&gt;" AnswerCount="10" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="204" PostTypeId="2" ParentId="201" CreationDate="2013-12-20T06:27:33.293" Score="12" Body="&lt;p&gt;A demonstrated crosswind component is highest crosswind (corrected to make it 90°) which has been shown to be possible to safely land by a test pilot. It shall not require exceptional skill by an ordinary pilot, however it does not mean every pilot will be able to do so. It is also NOT a limit (contrary to what some say) - if the pilot does decide to land higher crosswinds, they can do so (but please take caution).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This number may not necessarily be the highest crosswind component that it's possible to land in -- it just has to be above the minimum capabilities required in the regulations. For example, say an aircraft, flown perfectly (yes, we're dreaming), was capable of handling a 30 knot crosswind component (no gust, ISA conditions), the manufacturer only needs to demonstrate safe landing with a crosswind component of one-fifth of the reference stall speed in the landing configuration. This would be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;10 knots @ 50KIAS V&lt;sub&gt;S0&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;12 knots @ 60KIAS V&lt;sub&gt;S0&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;14 knots @ 70KIAS V&lt;sub&gt;S0&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;15 knots @ 75KIAS V&lt;sub&gt;S0&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7d1c7874017bd39fc5f2d31d120a6cf5&amp;amp;node=14:1.0.1.3.10.2.67.44&amp;amp;rgn=div8&quot;&gt;Reference&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) A 90 degree cross-component of wind velocity, demonstrated to be safe for taxiing, takeoff, and landing must be established and must be not less than 0.2 V&lt;sub&gt;S0&lt;/sub&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2013-12-21T00:06:44.730" LastActivityDate="2013-12-21T00:06:44.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="205" PostTypeId="1" AcceptedAnswerId="213" CreationDate="2013-12-20T06:31:21.600" Score="23" ViewCount="2159" Body="&lt;p&gt;I read that ADS-B is required by the year 2020. What does this mean? What is ADS-B used for, and who needs it?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="69" LastEditDate="2014-01-18T17:51:59.413" LastActivityDate="2016-01-29T20:52:00.970" Title="What is ADS-B and who needs it?" Tags="&lt;faa-regulations&gt;&lt;avionics&gt;&lt;ads-b&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="206" PostTypeId="2" ParentId="200" CreationDate="2013-12-20T06:48:47.997" Score="18" Body="&lt;p&gt;You should definitely not attempt flight if there is frost on the windows that would affect visibility, or on any of the wings or flight control surfaces.  Frost accumulation on such surfaces can reduce the lift generated by your wings, possibly causing a crash on takeoff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.ntsb.gov/doclib/safetyalerts/SA_006.pdf&quot;&gt;According to the NTSB&lt;/a&gt;, frost the size of a grain of salt, distributed as sparsely as one per square centimeter over a wing's upper surface, can destroy enough lift to prevent a plane from taking off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cheapest solution is to try to re-position the plane on the ramp so that the sunlight has a chance to melt it away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also temporarily move the plane into a heated hangar until it melts, or ask the FBO to do so for you.  If the forecast is predicting a chance of such conditions the night before, you can usually call the FBO on the night before and ask them to move your plane into their hangar just for the night, in advance of your morning flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're really anxious to go, you can ask the FBO to apply a heated deicing solution to your plane, but be prepared to pay for it (it's priced by the gallon and the amount needed will depend on the size and amount of frost of your plane).  Not all FBOs will have deicing capabilities, particularly if the region does not commonly experience such conditions.&lt;/p&gt;&#xA;" OwnerUserId="27" LastEditorUserId="27" LastEditDate="2014-01-16T03:59:06.250" LastActivityDate="2014-01-16T03:59:06.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="208" PostTypeId="2" ParentId="203" CreationDate="2013-12-20T07:11:09.813" Score="23" Body="&lt;p&gt;It's perfectly legal, but check the Chart Supplement (or AFD, or instrument approaches) to see if there are &lt;em&gt;special exceptions&lt;/em&gt; for that airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is a non-towered airport and you aren't assigned a runway, you should of course try to use the &lt;em&gt;prevailing runway&lt;/em&gt; that is already in use by other traffic in the pattern when it makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports have &lt;em&gt;obstructions in one direction&lt;/em&gt; of their runways that make it necessary (or safer) to always land or depart in a certain direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some runways have a steep incline in one direction, making it preferable to &lt;em&gt;land upslope&lt;/em&gt; and &lt;em&gt;depart downslope&lt;/em&gt;.  (For example &lt;a href=&quot;http://youtu.be/EfAw8ulhTiQ&quot; rel=&quot;noreferrer&quot;&gt;Lukla, Nepal: YouTube&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also common for larger airports to have &lt;em&gt;preferred directions&lt;/em&gt; for arrival or departures in order to keep the flight volume high, even when the wind prefers other runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, that usually relates to &lt;em&gt;operating with intentional crosswinds&lt;/em&gt; at an airport that has &lt;em&gt;parallel runways in a primary direction&lt;/em&gt; (allowing them to conduct more simultaneous flight operations), but not in the intersecting direction.&lt;/p&gt;&#xA;" OwnerUserId="27" LastEditorUserId="27" LastEditDate="2016-12-19T22:50:30.060" LastActivityDate="2016-12-19T22:50:30.060" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="209" PostTypeId="2" ParentId="205" CreationDate="2013-12-20T07:25:24.490" Score="4" Body="&lt;p&gt;ADS-B is a complex topic, but the FAA has mandated that by 2020 most aircraft operating in any airspace that currently requires a Mode C transponder should be &quot;ADS-B Out&quot; equipped, with minor exceptions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that it is possible to be &quot;ADS-B In&quot; equipped but not &quot;ADS-B Out&quot; equipped.  The FAA does not mandate anything regarding &quot;ADS-B In&quot; yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various &lt;a href=&quot;https://en.wikipedia.org/wiki/ADS-B#Benefits&quot; rel=&quot;nofollow&quot;&gt;safety and efficiency benefits&lt;/a&gt; of having ADS-B equipped aircraft.  ATC benefits from ADS-B Out by having more accurate position information, allowing them to potentially allow aircraft to operate closer to each other since current radar technology is far less accurate.  Pilots benefit from ADS-B In by being able to receive weather in the cockpit and see the depicted positions of aircraft around them for collision avoidance.&lt;/p&gt;&#xA;" OwnerUserId="27" LastEditorUserId="27" LastEditDate="2013-12-20T08:22:12.847" LastActivityDate="2013-12-20T08:22:12.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="210" PostTypeId="2" ParentId="167" CreationDate="2013-12-20T07:29:59.603" Score="8" Body="&lt;p&gt;As others have commented, it's really not much different than the average GA communications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of communicating with an FBO, airlines communicate with their company. (The company handles the aircraft part of it, anyway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The clearance controller exists just as it does in GA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There'll be a ground controller they need to ask before pushing back, but that's just because it's logistically a tad more difficult for two 737s to go around each other than two 172s. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tower (called &quot;local control&quot; in ATC) is just like you're used to - control of the runways and the immediate airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jets (and turboprops...) spend less time talking to Departure/Approach, and usually end up on Center frequencies much more quickly. There's various sectors, but again... it's no different than you're used to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The process then goes in reverse for landing as you'd expect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these (even the airline company frequencies at larger airports) are available on LiveATC. Try following one flight through from start to finish sometime!&lt;/p&gt;&#xA;" OwnerUserId="50" LastActivityDate="2013-12-20T07:29:59.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="211" PostTypeId="2" ParentId="198" CreationDate="2013-12-20T07:45:24.447" Score="65" Body="&lt;p&gt;I get this question a lot from people who are apprehensive about flying with a private pilot.  I'm afraid I won't be reducing these fears in any way.  Let's review some general statistics during 2008.  Note - these stats aren't specific to light or single engine aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://apps.bts.gov/publications/national_transportation_statistics/html/table_02_14.html&quot;&gt;NTSB&lt;/a&gt; reported there were 1.21 fatalities per 100,000 flight hours for private aircraft (Part 91 operators).  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www-fars.nhtsa.dot.gov/main/index.aspx&quot;&gt;NHTSA&lt;/a&gt; reported there were 1.26 fatalities per 100 million miles travelled by automobile&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;We can equate that to about 2 million hours (estimating an average speed of 50mph). This gives us 0.063 fatalities per 100,000 driving hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Private aircraft have a fatality rate about 19 times greater than driving.  It is also true that a majority of the accidents that occur are pilot error (71%) and could have been prevented. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are risks involved when taking to the sky as a private pilot and understanding these risks is part of the continual learning process.  The key to safety is performing careful planning, keeping current and proficient, knowing when to cancel flights or turn around and not to exceed your capabilities or the capabilities of your aircraft.  &lt;/p&gt;&#xA;" OwnerUserId="1" LastEditorUserId="753" LastEditDate="2014-11-21T15:21:45.043" LastActivityDate="2014-11-21T15:21:45.043" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="212" PostTypeId="2" ParentId="68" CreationDate="2013-12-20T07:50:09.350" Score="7" Body="&lt;p&gt;The manufacturer lists all maintenance that should be done, and when. This is the first document you found, from Boeing. Some of this maintenance may be required, other things might be recommended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The operator can use that plan, while following maintenance laws (e.g. the required annual inspection). Or, they can submit a new rolling maintenance plan to their National Aviation Authority (e.g. FAA) for approval, which is usually done to prevent large downtime events for the aircraft. (This &quot;rolling inspection&quot; is done so that all of the necessary things are inspected at the proper intervals, but not all at the same time.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a bit more, too: the Aviation Authorities can create Airworthiness Directives that can add additional required maintenance that must be done within certain limits (usually hourly, but can be situation dependent) for the aircraft to be airworthy.&lt;/p&gt;&#xA;" OwnerUserId="50" LastEditorUserId="97" LastEditDate="2013-12-20T18:15:03.460" LastActivityDate="2013-12-20T18:15:03.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="213" PostTypeId="2" ParentId="205" CreationDate="2013-12-20T10:09:06.100" Score="29" Body="&lt;p&gt;To answer your first question, ADS-B stands for Automatic Dependent Surveillance - Broadcast. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Automatic&lt;/strong&gt; in the sense that it operates without external stimulus (unlike radar)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Dependent&lt;/strong&gt; in the sense that the surveillance information is derived from on board systems&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Surveillance&lt;/strong&gt; in the sense that it's primary intended to provide surveillance information to other parties&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Broadcast&lt;/strong&gt; because it transmits to all listeners without knowing who those listeners are, there is no two-way communication.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The capability of an aircraft to transmit ADS-B signals is called &lt;strong&gt;ADS-B OUT&lt;/strong&gt;, the capability of an aircraft to receive ADS-B signals is called &lt;strong&gt;ADS-B IN&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B data contains information about the identity, position, altitude and velocity of the aircraft. The position and velocity information is derived from GNSS (GPS). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three technologies defined for ADS-B &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;1090ES&lt;/strong&gt; is operating on 1090 MHz, the same frequency used for Secondary Surveillance Radar (SSR) and Airborne Collision Avoidance Systems (ACAS/TCAS). Messages are transmitted by the same transponder that also replies to radar interrogations. This will be a Mode-S capable transponder because the data is formatted in a similar way. Since this frequency is the worldwide used standard for aviation, international aviation will use this ADS-B standard.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;UAT&lt;/strong&gt; (Universal Access Transceiver) works on 978 MHz. A special transceiver is required to use this form of ADS-B. The transceiver is able to send and receive data, it will also receive ADS-B transmissions from other aircraft. UAT is only allowed within the USA and China. The frequency 978 MHz is reserved for other purposes (DME/TACAN) in other countries.  To encourage people to equip with ADS-B voluntarily, the FAA provides additional services on UAT. These are Traffic Information Service - Broadcast (TIS-B) which transmits position of aircraft detected by FAA's SSR's and Flight Information Service - Broadcast (FIS-B) which provides the receiver with weather information and operational data such a airspace restrictions and NOTAMS. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;VHF Datalink Mode 4 (VLDm4)&lt;/strong&gt; uses a frequency in the 118-136.975 MHz block, which is internationally reserved for aviation. Normally these frequencies are used for voice communications, so a special radio is required to support VDLm4. Just like UAT, VDL mode 4 allows for services like TIS-B and FIS-B. VDLm4 was tried in Sweden and Russia, but has not been able to gather much mass. It is unlikely that it will be used on a large scale.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since you mention 2020 as the year by which aircraft should be equipped with ADS-B I am going to assume you are from FAA-land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA mandates aircraft in the 48 contiguous states (and D.C.) that operate in class A, B, or C airspace or class E airspace above 10000ft (class E airspace below 2500 AGL excluded) to be ADS-B OUT equipped by January 1st, 2020. &#xA;The mandate itself can be found &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/FR-2010-05-28/pdf/2010-12645.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and the associated Advisory Circular (AC90-114) can be found &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2090-114.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft operating below 18000 ft can use either UAT or 1090ES. Above 18000ft, 1090ES is to only approved ADS-B technology. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Countries that have ADS-B mandates are (this list is probably not exhaustive)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Australia&lt;/li&gt;&#xA;&lt;li&gt;Canada&#xA;(Hudson bay)&lt;/li&gt;&#xA;&lt;li&gt;China&lt;/li&gt;&#xA;&lt;li&gt;Countries in the &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2011:305:0035:0052:EN:PDF&quot; rel=&quot;noreferrer&quot;&gt;European Union&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Fiji&lt;/li&gt;&#xA;&lt;li&gt;Hong Kong&lt;/li&gt;&#xA;&lt;li&gt;India&lt;/li&gt;&#xA;&lt;li&gt;Indonesia&lt;/li&gt;&#xA;&lt;li&gt;Seychelles&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.caas.gov.sg/caasWeb2010/export/sites/caas/en/Regulations/Aeronautical_Information/AIP_Supplements/download/AIPSUP254-13.pdf&quot; rel=&quot;noreferrer&quot;&gt;Singapore&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/FR-2010-05-28/pdf/2010-12645.pdf&quot; rel=&quot;noreferrer&quot;&gt;USA&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Vietnam&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-01-29T20:52:00.970" LastActivityDate="2016-01-29T20:52:00.970" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="214" PostTypeId="5" CreationDate="2013-12-20T10:37:08.697" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2013-12-20T10:37:08.697" LastActivityDate="2013-12-20T10:37:08.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="215" PostTypeId="4" CreationDate="2013-12-20T10:37:08.697" Score="0" Body="Radar is a surveillance technology that uses radio waves to determine the range (and azimuth) of an aircraft. It works by measuring the time difference between a radio transmission and the echo or reply to that transmission. Radars are the most common surveillance equipment used by ATC." OwnerUserId="97" LastEditorUserId="19" LastEditDate="2014-01-15T15:06:05.063" LastActivityDate="2014-01-15T15:06:05.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="216" PostTypeId="2" ParentId="203" CreationDate="2013-12-20T11:32:24.167" Score="17" Body="&lt;p&gt;Yes, aircraft do take-off and land downwind sometimes. During low wind conditions it is sometimes preferable to use a runway in the downwind direction for noise abatement reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During downwind landing the ground speed will be higher and therefore it takes more distance to stop the aircraft. This increases the risk of a runway excursion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During downwind departure a higher ground speed is needed to take-off and therefore a longer runway will be required. An other effect is that the climb-out angle is lower due to tailwind, lowering the obstacle clearance and increasing the risk of Controlled Flight Into Terrain (CFIT). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial aircraft have limits one the amount of tailwind that is allowed on take-off and landing. For most aircraft it is 10 or 15 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information about the safety aspects of tailwind operations see &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1148.pdf&quot;&gt;this report&lt;/a&gt; by NLR. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-05T08:36:31.463" LastActivityDate="2014-02-05T08:36:31.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="217" PostTypeId="2" ParentId="203" CreationDate="2013-12-20T12:25:43.277" Score="11" Body="&lt;p&gt;In the case of motorless flight (preferrably intentionally, i.e. with a glider) the choice of landing direction for an outlanding is very strongly influenced by the terrain. Of course it is much preferrable to land with headwind, but in uneven terrain this can be impossible. In sloping terrain, it can be better (or compulsory) to land into direction of the steepest rise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same thing also can be the case for landing or (reversed) for takeoff on airports with very pronounced runway slopes (mostly in mountaineous terrain, e.g. in &lt;a href=&quot;https://en.wikipedia.org/wiki/Courchevel_Airport&quot;&gt;Courchevel&lt;/a&gt;), or glacier landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, it is simply convenient to land downwind, again esp. for motorless aircraft to reduce the distance to the hangar - conditions permitting, of course.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2013-12-20T12:41:04.590" LastActivityDate="2013-12-20T12:41:04.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="218" PostTypeId="2" ParentId="202" CreationDate="2013-12-20T15:48:30.167" Score="18" Body="&lt;p&gt;Under some conditions, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&amp;amp;rgn=div5#14:2.0.1.3.10.4.7.12&quot;&gt;FAR §91.323&lt;/a&gt; allows for a 15% increase (up to 12,500 lbs) in max gross weight in Alaska:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Notwithstanding any other provision of the Federal Aviation Regulations, the Administrator will approve, as provided in this section, &lt;strong&gt;an increase in the maximum certificated weight of an airplane&lt;/strong&gt; type certificated under Aeronautics Bulletin No. 7–A of the U.S. Department of Commerce dated January 1, 1931, as amended, or under § 91.325 14 CFR Ch. I (1–1–05 Edition) the normal category of part 4a of the former Civil Air Regulations (14 CFR part 4a, 1964 ed.) if that airplane is &lt;strong&gt;operated in the State of Alaska&lt;/strong&gt; by—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;A certificate holder &lt;strong&gt;conducting operations under part 121 or part 135&lt;/strong&gt; of this chapter; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The U.S. Department of Interior in conducting its game and fish law enforcement activities or its management, fire detection, and fire suppression activities concerning public lands.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(b) The maximum certificated weight approved under this section may not exceed—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;12,500 pounds;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;115 percent of the maximum weight listed in the FAA aircraft specifications;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The weight at which the airplane meets the positive maneuvering load factor requirement for the normal category specified in § 23.337 of this chapter; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The weight at which the airplane meets the climb performance requirements under which it was type certificated.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(c) In determining the maximum certificated weight, the Administrator considers the structural soundness of the airplane and the terrain to be traversed.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) The maximum certificated weight determined under this section is added to the airplane's operation limitations and is identified as the maximum weight authorized for operations within the State of Alaska.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One possible reason for this is that Alaska Statute Section 02.35.110 requires aircraft operating to/from and within Alaska to carry additional emergency and survival equipment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) An airman may not make a flight inside the state with an aircraft unless emergency equipment is carried as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;the following minimum equipment must be carried during the summer months:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;rations for each occupant sufficient to sustain life for one week;&lt;/li&gt;&#xA;  &lt;li&gt;one axe or hatchet;&lt;/li&gt;&#xA;  &lt;li&gt;one first aid kit;&lt;/li&gt;&#xA;  &lt;li&gt;an assortment of tackle such as hooks, flies, lines, and sinkers;&lt;/li&gt;&#xA;  &lt;li&gt;one knife;&lt;/li&gt;&#xA;  &lt;li&gt;fire starter;&lt;/li&gt;&#xA;  &lt;li&gt;one mosquito headnet for each occupant;&lt;/li&gt;&#xA;  &lt;li&gt;two small signaling devices such as colored smoke bombs, railroad fuses, or Very pistol shells, in sealed metal containers.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;in addition to the equipment required under (1) of this subsection, the following must be carried as minimum equipment from October 15 to April 1 of each year:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;one pair of snowshoes;&lt;/li&gt;&#xA;  &lt;li&gt;one sleeping bag;&lt;/li&gt;&#xA;  &lt;li&gt;one wool blanket or equivalent for each occupant over four.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(b) However, operators of multi-engine aircraft licensed to carry more than 15 passengers need carry only the food, mosquito nets, and signalling equipment at all times other than the period from October 15 to April 1 of each year, when two sleeping bags, and one blanket for every two passengers shall also be carried. All of the above requirements as to emergency rations and equipment are considered to be minimum requirements which are to remain in full force and effect, except as further safety measures may be from time to time imposed by the department.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2013-12-21T17:31:01.127" LastActivityDate="2013-12-21T17:31:01.127" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="219" PostTypeId="2" ParentId="203" CreationDate="2013-12-20T17:26:39.140" Score="15" Body="&lt;p&gt;Landing downwind is often the only option when flying an instrument approach procedure to minimums (the lowest ceiling at which landing is permitted).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many airports only have approaches to one runway direction. In the event that the approach is required and circling is not possible, a straight-in downwind landing is the pilot's only option. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, given an approach to runway &lt;strong&gt;27&lt;/strong&gt; with winds of &lt;strong&gt;8 knots at 080&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Circling MDA      | 1100 feet MSL&#xA;Straight-in DA    |  700 feet MSL&#xA;Field elevation   |  450 feet MSL&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;If the clouds are below 1100 feet, a pilot would be unable to circle to the &quot;correct&quot; runway  09; they would have to land straight in to 27, which is a &lt;strong&gt;downwind landing&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Given the aircraft I personally fly, I will avoid doing so and divert to an alternate if the tailwind is higher than 10 knots or the runway is shorter than 4500 feet. Tailwind landings are inherently riskier and I'd rather take the delay.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-20T21:44:47.913" LastActivityDate="2013-12-20T21:44:47.913" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="220" PostTypeId="2" ParentId="200" CreationDate="2013-12-20T17:46:17.137" Score="15" Body="&lt;p&gt;I don't know if you're in the US, but if so then by regulation you must remove it from all critical areas before flight, per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=76362b848e2f847cca599309779d5140&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.6.7.14&amp;amp;idno=14&quot;&gt;14 CFR 91.527&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.527   Operating in icing conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No pilot may take off an airplane that has frost, ice, or snow&#xA;  adhering to any propeller, windshield, stabilizing or control surface;&#xA;  to a powerplant installation; or to an airspeed, altimeter, rate of&#xA;  climb, or flight attitude instrument system or wing, except that&#xA;  takeoffs may be made with frost under the wing in the area of the fuel&#xA;  tanks if authorized by the FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In practice, that really means removing it all, and I guess that other countries have similar rquirements. The NTSB has a detailed &lt;a href=&quot;http://www.ntsb.gov/doclib/safetyalerts/SA_006.pdf&quot;&gt;guide&lt;/a&gt; on ground icing where they say that it must be removed &quot;by any means necessary&quot; before flight. For light aircraft, the usual recommendation is to hangar the aircraft and let the frost melt off. But you need to ensure any moisture is completely removed before flying, otherwise it may re-freeze.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger transport aircraft (or any aircraft, in principle) are usually de-iced, which is a common sight at airports in winter. The FAA has an extremely detailed &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/deicing/media/standardized_international_ground_deice_program.pdf&quot;&gt;document&lt;/a&gt; if you're curious.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-20T17:46:17.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="221" PostTypeId="1" AcceptedAnswerId="223" CreationDate="2013-12-20T18:00:12.693" Score="27" ViewCount="39221" Body="&lt;p&gt;To most non-U.S. pilots who have little or no experience flying in the U.S., the concept of a FBO is not very well understood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is a FBO and what are the services that it can provide? I've heard that they can refuel your plane, move it to a hangar, clean it, provide preflight planning facilities, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a charge for these services (I guess so) and if so, what can be expected? I've also seen many airports with multiple FBOs. How does that work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All I know is that FBO stands for &quot;Fixed Base Operator&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may seem like a very stupid question but in Europe there's no such thing. If you need fuel you either taxi to the pump and fill up or call up the fuel provider (if you're lucky because they usually only serve private jets).&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2020-08-17T07:30:46.380" Title="What exactly is an FBO and what services are provided?" Tags="&lt;airport&gt;&lt;fbo&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="222" PostTypeId="2" ParentId="203" CreationDate="2013-12-20T18:03:02.033" Score="10" Body="&lt;p&gt;I fly small Cessna aircraft, but frequently fly out of airports with 10,000 ft. runways.  (A C-172 typically needs around 1,500 ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when its more convenient for me, I can ask the Tower for an &quot;Opposite Direction Departure&quot;, meaning that I want to take off with the wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does take me a little more time to get my airspeed up and take off, but so long as I have plenty of runway in front of me, its not a problem.  And it generally means I can take off more directly towards my course, instead of taking off, flying a pattern around the airport, then getting on course.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2013-12-20T18:03:02.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="223" PostTypeId="2" ParentId="221" CreationDate="2013-12-20T18:31:24.907" Score="25" Body="&lt;p&gt;A Fixed Base Operator (FBO) is an entity - usually a commercial company - which provides &quot;aviation services&quot; at an airport. One of the main services they provide is fueling, either full service or a self service pump.  They don't all provide both 100LL and JetA, but most do.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger ones provide other services, such as catering, lavatory service, pre-flight briefing computers and wifi access, ground power units, and tie down or hangar space for parking.  Charges vary from place to place, most large FBOs will charge a fee for aircraft parking, but sometimes waive a day or so of that if you purchase fuel.  They can often assist in arranging ground transport or hotels as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most are open hours like 7AM - 8PM, but that varies as well.  Most self-service pumps can be used 24 hours a day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some have a &quot;crew car&quot; available to borrow for a short trip to get lunch or run an errand, though calling ahead to check on that is important.&lt;/p&gt;&#xA;" OwnerUserId="143" LastEditorUserId="64" LastEditDate="2014-01-08T21:46:02.010" LastActivityDate="2014-01-08T21:46:02.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="224" PostTypeId="2" ParentId="39" CreationDate="2013-12-20T19:38:06.337" Score="1" Body="&lt;p&gt;I have no personal experience of this question but it is &lt;a href=&quot;https://easa.europa.eu/flightstandards/faq.html#thirdcountryconversion&quot; rel=&quot;nofollow&quot;&gt;included&lt;/a&gt; in the EASA &lt;a href=&quot;https://easa.europa.eu/flightstandards/faq.html&quot; rel=&quot;nofollow&quot;&gt;Flight Standard FAQ&lt;/a&gt;. The key point seems to me to be this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The competent authority of the Member State to which an applicant&#xA;  applies will determine the conversion requirements, which can be&#xA;  reduced on the basis of a recommendation from an approved training&#xA;  organisation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Therefore, the national aviation authority of the Member State where&#xA;  an applicant resides or wishes to work should be contacted for further&#xA;  information concerning the applicable acceptance requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, the exact requirements are determined locally by the EASA member state you live in and/or want to fly in. Perhaps someone who's actually been through the process could give a better answer.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-20T19:38:06.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="225" PostTypeId="1" AcceptedAnswerId="363" CreationDate="2013-12-20T20:55:19.030" Score="9" ViewCount="5354" Body="&lt;p&gt;Is there a good website which shows airports (both public and GA)? I can look it on Google and Bing Maps (as shown in the image below). Shown the picture, I have zoomed in a lot to see airport icons (bottom left and top right). I feel that the icon on Bing (right) can be easily spotted than the one on Google (left). Even if I zoom out one level, Bing still shows both airports but Google doesn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I search on Internet, mostly A/F Directories are returned. Wikipedia also has a thorough list but I don't like plotting them on a map to find their proximity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k2tfg.jpg&quot; alt=&quot;Google and Bing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="97" LastEditDate="2014-04-03T22:57:12.487" LastActivityDate="2016-12-23T17:34:44.620" Title="Is there a website which highlights airport locations on a map?" Tags="&lt;airport&gt;&lt;website&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="226" PostTypeId="2" ParentId="225" CreationDate="2013-12-20T21:03:54.913" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://skyvector.com&quot;&gt;SkyVector&lt;/a&gt; is a great resource for aviation maps and data of all kinds. It offers worldwide sectional- and low-ifr-type charts, and a fully-featured &lt;a href=&quot;http://skyvector.com/airports&quot;&gt;Airports section&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if you also want airport diagrams, but you may also get some decent results with &lt;a href=&quot;http://openstreetmap.org&quot;&gt;OpenStreetMap&lt;/a&gt;. The open source maps have some hit-or-miss levels of detail for airports, some including full taxiway and runway data. Others are just property outlines.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-20T21:03:54.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="227" PostTypeId="2" ParentId="183" CreationDate="2013-12-20T21:04:32.677" Score="17" Body="&lt;p&gt;From a private pilot's perspective, there are two possible options: a foreign-based license or a 'full' FAA pilot's license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first type is defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.2.1.10&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.75&lt;/a&gt;, which starts like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§61.75   Private pilot certificate issued on the basis of a foreign&#xA;  pilot license.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) General. A person who holds a foreign pilot license at the private&#xA;  pilot level or higher that was issued by a contracting State to the&#xA;  Convention on International Civil Aviation may apply for and be issued&#xA;  a U.S. private pilot certificate with the appropriate ratings if the&#xA;  foreign pilot license meets the requirements of this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You apply to the FAA and they check with Germany (or wherever) that your foreign license is valid. If it is, they'll issue a foreign-based license &quot;with the appropriate ratings&quot; with no flight or theory test of any kind required. That's for VFR only; if you're instrument rated then you also have to do a theory test as well if you want to fly IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That sounds great - and I suppose it is - but there are two big practical concerns. First, any limitations on the foreign license are applied, e.g. if your license is for daytime VFR only then you're still restricted to that, even if a regular FAA license would allow night VFR. And if your foreign license expires or becomes invalid for any reason, the FAA one does too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, you won't have been required to learn anything about US regulations or flying practices. So you might not fly safely or legally because you simply don't know the rules or even what services are available to you as a pilot (FSS, Flight Following, TRSA etc.). One way to handle this is to get some general orientation or introductory training from a US instructor or school, but as a foreigner that will require TSA approval unless you can do it as ground school only (which is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=aab5506849ce022b72a376259dfecffd&amp;amp;node=49:9.1.3.5.16.1.10.2&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;not defined&lt;/a&gt; as &quot;flight training&quot;). But you might find - as I did - that some instructors will not work with a foreign student at all until they have TSA approval, whether or not it's just ground work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other option is to get a normal, full FAA license. You have to pass the same FAA medical, written and flight tests as US pilots to the same &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot; rel=&quot;noreferrer&quot;&gt;standards&lt;/a&gt;. You can count your previous flight time towards the required hours but you do need to be able to pass the tests so you will certainly need some instruction. And as a foreigner you will need TSA approval before you can receive any flight training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big advantage of getting a full license is that it never expires. If you really want to get one and you have the time and money then you could look into spending a month somewhere suitable in the US (Florida? Arizona?) at a flight school to get it as quickly and cheaply as possible.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-06-26T17:50:27.487" LastActivityDate="2014-06-26T17:50:27.487" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="229" PostTypeId="2" ParentId="63" CreationDate="2013-12-20T22:04:42.223" Score="20" Body="&lt;p&gt;Unfortunately, at least in the US, the regulations don't stipulate that &lt;strong&gt;you&lt;/strong&gt; do &lt;em&gt;anything&lt;/em&gt;. Airline policy is a different matter, and one which I cannot speak to, as it will be different in every case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can provide some background and my own take on this, but it's hard to have one exact answer (what if you're wrong?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA regulations rely on pilots self-regulating. If a pilot drinks within an 8 hour (or, as is often policy for airlines, 12 hour) window prior to the flight, they are required to remove themselves from that flight. If they do not take this action, &lt;em&gt;somebody else must&lt;/em&gt;. Often, this person is the First Officer, a junior pilot who has years of flying with pilots who might come to view them as untrustworthy. Perhaps this can help explain why it's such a difficult action to take.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is a difficult topic, and one which regularly comes up during airline flight training. That said, the courses I took that discussed this scenario essentially landed on a couple of steps (this was years ago, this is probably a bit rusty):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Confront the pilot. Ask them if they've been drinking in the last X hours. If they claim they have not been, or they push back:&lt;/li&gt;&#xA;&lt;li&gt;Attempt to explain to them the situation they're putting their career (and you) in;&lt;/li&gt;&#xA;&lt;li&gt;Try to get them to remove themselves from the flight and contact a union representative.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Beyond that, I don't want to make suggestions. Getting them to talk to the union they are a member of is probably a wise idea, as they can offer possible solutions or arrange treatment if the pilot has alcohol abuse problems (which is not a huge stretch, if they're showing up to work reeking of booze). &lt;a href=&quot;http://blog.aopa.org/flighttraining/?p=1240&quot;&gt;AOPA Flight Training&lt;/a&gt; has a blog post that discusses some similar scenarios.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-20T23:16:17.387" LastActivityDate="2013-12-20T23:16:17.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="230" PostTypeId="2" ParentId="199" CreationDate="2013-12-20T22:28:39.223" Score="9" Body="&lt;p&gt;While probably legal to fly over the Atlantic VFR, it appears getting out of Canadas airspace is a different matter. After a bit of googling I found &lt;a href=&quot;http://www.copanational.org/CC-42.cfm&quot;&gt;this article&lt;/a&gt; on COPA's website, saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Both for flying in the northern parts of Canada as well as in&#xA;  Greenland airspace, an ADF is legally required (refer to TC AIM&#xA;  3.16.10 and CAR 605.18). I didn’t have one, so one had to be installed. Other than that, FDOW didn’t need any modifications. IFR&#xA;  approved GPS is an absolute must; we had three GPS receivers on board.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Speaking of IFR: As per CAR 602.19, pilots attempting trans-oceanic&#xA;  flight must hold an instrument rating. Even though an IFR flight plan&#xA;  is only required above 5,500 feet across the Atlantic, NavCanada will&#xA;  not issue an oceanic VFR clearance when leaving Canada. In addition,&#xA;  it is extremely unlikely for any airplane to stay in VMC during the&#xA;  whole trans-Atlantic flight. Therefore, it’s mandatory that both,&#xA;  pilot and airplane are certified and current IFR.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, weather over the Atlantic can be very treacherous, especially if you're unable to climb on top.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are quite a few stories around about crossing the Atlantic in smaller airplanes, there's also an &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Ice_Pilots_NWT_episodes&quot;&gt;Ice Pilots NWT episode&lt;/a&gt; (season 1 episode 9) where they ferry two water-bombers to Turkey, although not very technical, it's a nice watch.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2013-12-20T22:28:39.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="231" PostTypeId="2" ParentId="145" CreationDate="2013-12-20T23:13:09.513" Score="2" Body="&lt;p&gt;From the &lt;a href=&quot;http://www.latimes.com/nation/la-na-drones-rules-20131108,0,3969978.story#ixzz2o3lERUvp&quot; rel=&quot;nofollow&quot;&gt;second link you posted&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Until regulations establish who can fly a drone and where, Huerta said, the FAA will license drone operators on a case-by-case basis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's doubtful that getting an airplane or helicopter pilot certificate will aid legally with the transition. It could obviously help with the concepts, but until the FAA releases an NPRM (Notice of Proposed Rule Making), the best we can do is guess.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-20T23:13:09.513" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="232" PostTypeId="2" ParentId="158" CreationDate="2013-12-21T02:10:51.290" Score="10" Body="&lt;p&gt;Well, a balloon already &lt;strong&gt;&lt;em&gt;is&lt;/em&gt;&lt;/strong&gt; an aircraft, specifically:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A balloon is a lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you were to attach engine-driven propellers to your balloon it would no longer be a &quot;balloon&quot;. It would start to sound a lot more like another kind of aircraft -- an airship:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An airship is an engine-driven, lighter than air vehicle that can be controlled in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So from a licensing standpoint there would appear to be two major considerations: First the pilot of such a chimera would need to be licensed to act as pilot in command of an airship (not a balloon), and second the modification itself would have to go through appropriate regulatory channels, since it is changing the fundamental nature of the aircraft in a way that would almost certainly attract some scrutiny.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Specifically regarding the fans/propellers you're talking about, it looks like those are intended for use as &lt;em&gt;inflation fans&lt;/em&gt; to help you out when you're setting a hot-air balloon up - once you've got the envelope inflated and the heater is doing its job you don't really need the fan anymore, and you would leave it with your ground crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can tell they aren't intended for use as engines for moving and steering a balloon - I suppose you could carry one aloft with you if you were feeling bold, but I'm not sure what the impact of doing so would be from a regulatory standpoint when it's not permanently attached to the balloon, and I'm not sure how effective they would be as propulsion with only a few horsepower behind them.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-21T02:27:21.683" LastActivityDate="2013-12-21T02:27:21.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="233" PostTypeId="1" AcceptedAnswerId="234" CreationDate="2013-12-21T02:26:09.903" Score="20" ViewCount="39882" Body="&lt;p&gt;I know that in most piston aircraft that there is a mixture control for the engine. My question is, how does the mixture control affect the engine's operation and what type of situations dictate a particular mixture setting? Would an incorrect mixture setting be detrimental, a minor effect or nothing at all?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-04-02T00:31:52.177" LastActivityDate="2018-12-17T00:46:10.710" Title="How does the mixture of an engine affect the engine's operation?" Tags="&lt;piston-engine&gt;&lt;mixture&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="234" PostTypeId="2" ParentId="233" CreationDate="2013-12-21T03:36:54.267" Score="25" Body="&lt;p&gt;Simple Answer: Running the engine lean or rich at different altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer Answer: There are a couple of reasons you want to adjust the mixture of a aircraft engine.  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Since air density changes with altitude, it's a good idea to be able to change the fuel/air mixture at different altitudes.  If you did not adjust the mixture at high altitudes you may not get full power because the air is thinner and now there is same amount of fuel being mixed with less air.  All the unburnt fuel can cause issues like loss of power and/or fouling of plugs.&lt;/li&gt;&#xA;&lt;li&gt;Being able to lean the mixture at higher altitude lets you save fuel, so you can go further on a full tank.  (hence saving money)&lt;/li&gt;&#xA;&lt;li&gt;Running a engine rich can help cool engine.  Fuel acts like a coolant in this manner.  Typically on climbing you want to run the engine a bit rich because your going slower and less air is able to help cool the engine.&lt;/li&gt;&#xA;&lt;li&gt;Traditional piston powered aircraft engines are shut off by pulling the mixture to the off position.  This starves the engine and burns off remaining fuel in the cylinders.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This topic can also bring up other discussions.  Like EGT, CHT, running an engine rich of peak or lean of peak, monitoring fuel flow rate with a flow meter, and fuel injectors on fuel injected systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;" OwnerUserId="150" LastEditorUserId="938" LastEditDate="2014-04-02T19:35:51.327" LastActivityDate="2014-04-02T19:35:51.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="235" PostTypeId="2" ParentId="233" CreationDate="2013-12-21T04:24:45.873" Score="9" Body="&lt;p&gt;The mixture control allows you to increase (to run &quot;richer&quot;) or decrease (to run &quot;leaner&quot;) the amount of fuel in the fuel-air mixture. As a general rule, you want to &quot;lean out&quot; the engine at higher altitudes because the air is thinner, and it takes more air (by volume) to burn the same amount of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mixture controls are used with many piston engines. However, turbine engines and some piston engines with fuel injection or altitude compensating carburetors do not have mixture controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to zingle-dingle's points, it is important to lean an engine for takeoff at high elevations. At a 7,000 ft (or higher) runway, for example, an engine with a full-rich mixture setting will not generate nearly as much power as one properly leaned out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the normal mixture setting at low-elevation airports may be full-rich, this may come as a surprise to someone visiting the mountains. It's not uncommon for a plane to crash at a high elevation airport because the engine was not leaned properly for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, if an engine is properly leaned out at 14,000 ft., for example, the mixture should be adjusted to be more rich on or before a descent to 1,000 ft. to prevent engine overheating or possible stoppage due to too little fuel in the fuel/air mixture.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-21T16:11:00.290" LastActivityDate="2013-12-21T16:11:00.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="236" PostTypeId="2" ParentId="158" CreationDate="2013-12-21T05:58:01.800" Score="10" Body="&lt;p&gt;Yes, a hot air balloon would change class, if you are adding an engine and propeller to provide thrust. With powered flight comes the need to provide some form of flight control; at this point, you have an airship, albeit a &lt;a href=&quot;http://en.wikipedia.org/wiki/Thermal_airship&quot;&gt;thermal airship&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the FAA's &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/airships/airships_regs/media/aceAirshipDesignCriteria.pdf&quot;&gt;Airship Design Criteria&lt;/a&gt;, and much like @voretaq7's citation in another answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An airship is an engine-driven, lighter-than-air aircraft, that can be steered.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA has a whole section on &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/airships/&quot;&gt;Airships&lt;/a&gt;, for further reading.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-21T05:58:01.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="237" PostTypeId="2" ParentId="70" CreationDate="2013-12-21T06:15:51.050" Score="10" Body="&lt;p&gt;As a privately-operated aircraft, this is probably not going to be a question which is completely answerable. All that is available is best guesses and incomplete information!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, the An-225's &lt;a href=&quot;http://flightaware.com/live/flight/UR82060&quot; rel=&quot;noreferrer&quot;&gt;last tracked flight&lt;/a&gt; on FlightAware – as of today – was March 15, 2012 between Bangor, Maine (KBGR) and Port Harcourt, Nigeria (DNPO). That suggests that the An-225 is either being excluded from flight tracks, or simply hasn't visited the US since early 2012.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from that, the only other likely place for flight information is photo sharing websites like &lt;a href=&quot;http://airliners.net&quot; rel=&quot;noreferrer&quot;&gt;airliners.net&lt;/a&gt; and &lt;a href=&quot;http://www.flickr.com/search/?q=an225&amp;amp;s=rec&quot; rel=&quot;noreferrer&quot;&gt;flickr&lt;/a&gt;, or on &lt;a href=&quot;http://youtube.com&quot; rel=&quot;noreferrer&quot;&gt;youtube&lt;/a&gt;. Browsing through flickr, I tried to track down dates of recent photos in unique locations (which is a guess at best):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;May 21 2013&#xA;June 24 2013&#xA;September 25 2013&#xA;September 26 2013&#xA;November 12 2013&#xA;November 17 2013&#xA;December 10 2013&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are more, but I stopped searching. It looks like it's probably doing charter cargo trips at most a couple of times a month, which is honestly more frequently than I expected! If you're interested, I'd encourage you to track down more on the sources I mentioned.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-21T06:15:51.050" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="238" PostTypeId="1" AcceptedAnswerId="242" CreationDate="2013-12-21T06:27:26.097" Score="10" ViewCount="2654" Body="&lt;p&gt;I've read that SFO has a specialized FMS Bridge Visual approach to 28R that is not published but instead is custom tailored for specific operators. What exactly is this approach and how does it work? When is it assigned, and what advantage does it have over other visual approaches to runway 28R?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="69" LastEditDate="2013-12-30T21:51:31.593" LastActivityDate="2019-06-01T21:36:27.050" Title="What is the FMS Bridge Visual 28R approach at SFO?" Tags="&lt;fms&gt;&lt;sfo&gt;&lt;iaps&gt;&lt;visual-approaches&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="239" PostTypeId="1" CreationDate="2013-12-21T06:43:31.913" Score="9" ViewCount="4767" Body="&lt;p&gt;I recently read about flap load relief systems in some aircraft that attempt to prevent flap overspeeds by automatically retracting flaps under certain conditions.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are these systems common on all large aircraft or are they specific to just a few?&lt;/li&gt;&#xA;&lt;li&gt;How do they work (i.e. under what conditions will they retract flaps)?&lt;/li&gt;&#xA;&lt;li&gt;Do they prevent the possibility of overspeeding flaps altogether, or do they just make it less likely to happen?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="79" LastEditorUserId="65" LastEditDate="2015-03-03T15:28:06.200" LastActivityDate="2015-03-03T15:29:34.100" Title="How does a flap load relief system work?" Tags="&lt;flaps&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="240" PostTypeId="1" CreationDate="2013-12-21T07:25:46.840" Score="9" ViewCount="3300" Body="&lt;p&gt;Half bank can make turns more comfortable for passengers, but ATC expects turns to be at standard rate much (most?) of the time.  When is it permissible to use half bank?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2013-12-21T13:33:14.440" LastActivityDate="2013-12-21T20:42:31.547" Title="When should the half bank mode of an autopilot be used?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;autopilot&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="241" PostTypeId="1" CreationDate="2013-12-21T14:07:08.730" Score="13" ViewCount="18296" Body="&lt;p&gt;What makes a constant speed prop different from a fixed pitch prop, and what are the operational differences between airplanes with the two?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="41" LastEditDate="2013-12-21T18:08:01.030" LastActivityDate="2014-01-28T21:35:18.277" Title="What are the operational differences between an airplane equipped with a constant speed propeller and one with a fixed pitch propeller?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="242" PostTypeId="2" ParentId="238" CreationDate="2013-12-21T15:53:43.290" Score="7" Body="&lt;p&gt;The &lt;strong&gt;&lt;em&gt;FMS Bridge Visual Approach 28R&lt;/em&gt;&lt;/strong&gt; is a version of the &lt;strong&gt;&lt;em&gt;Quiet Bridge Visual Approach 28R&lt;/em&gt;&lt;/strong&gt; which is coded with GPS coordinates and can be included in an FMS database for approved operators.  This allows the procedure to be used when the SFO &#xA;VOR is out of service, and also gives ATC additional flexibility by allowing them to clear pilots direct to any of the fixes without needing to intercept the radial on the standard arrival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot must either tell ATC that they can accept it verbally, or include &lt;strong&gt;&lt;em&gt;FMS28R ABLE&lt;/em&gt;&lt;/strong&gt; in the remarks of their flight plan so that they know that the flight is capable of flying the approach.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-21T15:53:43.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="243" PostTypeId="1" AcceptedAnswerId="244" CreationDate="2013-12-21T16:03:33.460" Score="9" ViewCount="1147" Body="&lt;p&gt;The FARs (or &lt;strong&gt;Federal Aviation Regulations&lt;/strong&gt;) are the regulations imposed by the FAA on aviation within the United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many questions make reference to FAR 23, or FAR 91 etc. What are each of these? Where can one lookup the text?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="69" LastEditDate="2014-01-18T18:05:26.313" LastActivityDate="2015-05-03T04:06:07.920" Title="What are FARs &amp; where can I find them? What is FAR 23, 25, 135, etc?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="244" PostTypeId="2" ParentId="243" CreationDate="2013-12-21T16:03:33.460" Score="5" Body="&lt;p&gt;In the US the &quot;Federal Aviation Regulations&quot; (FARs) is shorthand for referring to Title 14 of the Code of Federal Regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can browse all sections of FARs at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14tab_02.tpl&quot; rel=&quot;nofollow&quot;&gt;ECFR.Gov&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR 23, for example, covers airworthiness standards. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.10&amp;amp;rgn=div5#14:1.0.1.3.10.2.59.3&quot; rel=&quot;nofollow&quot;&gt;§ 23.25&lt;/a&gt; regulates weight limits.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-05-03T04:06:07.920" LastActivityDate="2015-05-03T04:06:07.920" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="245" PostTypeId="1" CreationDate="2013-12-21T16:20:35.297" Score="12" ViewCount="3598" Body="&lt;p&gt;When flying at higher altitudes, does it matter if you have a turboprop vs a piston engine driving a propeller? &lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="1696" LastEditDate="2015-02-23T21:55:49.403" LastActivityDate="2015-02-23T21:55:49.403" Title="Do turboprop and piston engines perform differently at higher altitudes?" Tags="&lt;propeller&gt;&lt;turboprop&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="246" PostTypeId="1" AcceptedAnswerId="35934" CreationDate="2013-12-21T16:24:25.000" Score="15" ViewCount="1506" Body="&lt;p&gt;The MD-900 is a helicopter which seems to be quite popular with law enforcement agencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0fle.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, instead of an anti-torque tail rotor, a fan exhaust is directed out slots in the tail boom. I was wondering if this works in regards to auto rotation, should the aircraft lose its engines.&lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="1696" LastEditDate="2015-02-09T18:20:47.300" LastActivityDate="2017-03-01T21:02:20.890" Title="How does the MD 900 accomplish auto rotation with the NOTAR system?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="247" PostTypeId="2" ParentId="241" CreationDate="2013-12-21T16:24:49.483" Score="7" Body="&lt;p&gt;A constant speed propeller runs at a specific rpm by changing the blade pitch. When the blades are at a lower pitch (i.e., flatter angle), there is less air resistance, so the propeller puts less drag on the engine and runs faster. Additional pitch causes more drag and slower RPM. A governor (or something similar) will adjust the blade pitch to keep the propeller running at a particular rpm, even when more or less power is produced by the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A constant speed prop is typically found on more powerful engines. Constant speed props are more efficient, but are more complex and heavier than fixed pitch props.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some planes have a prop speed control for the pilot to adjust the propeller rpm, and some, such has the Cirrus SR22 and Pilatus PC12 have a single prop speed for flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The operation of a variable pitch prop depends on the plane. For example, in a Cirrus SR22 you don't even have a propeller pitch control. You operate it just like a fixed pitch prop. With a Pilatus PC12, the only prop pitch adjustments are when you feather the prop on engine shutdown or reverse the prop pitch for landing or ground operations. In a Beech Bonanza A36, you adjust the prop pitch for max RPM (minimum pitch) on takeoff, then add pitch for cruise flight, and max RPM for landing (in case of go-around).&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-30T03:55:16.850" LastActivityDate="2013-12-30T03:55:16.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="248" PostTypeId="1" CreationDate="2013-12-21T16:32:44.233" Score="12" ViewCount="916" Body="&lt;p&gt;Piloting an aircraft, if skydivers cannot jump on a flight, what should I take care of when landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any special recommendations which should be taken into account?&lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="97" LastEditDate="2013-12-21T17:23:27.533" LastActivityDate="2015-06-25T20:21:36.493" Title="If skydivers cannot jump on a flight, what should I take care of when landing?" Tags="&lt;landing&gt;&lt;skydiving&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="249" PostTypeId="2" ParentId="248" CreationDate="2013-12-21T16:32:44.233" Score="20" Body="&lt;p&gt;You should descend in a controlled way, taking into account that your descent rate should be ≤ 29 mph (less than 13 m/s), once below 2,500 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the descent rate is higher than that, then there is a risk of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_activation_device&quot; rel=&quot;noreferrer&quot;&gt;AAD&lt;/a&gt; popping the skydiver's reserve parachute, mid-flight.&lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="8300" LastEditDate="2015-06-25T20:21:36.493" LastActivityDate="2015-06-25T20:21:36.493" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="250" PostTypeId="2" ParentId="245" CreationDate="2013-12-21T16:35:27.567" Score="11" Body="&lt;p&gt;In general, a turbine engine will produce more power than a piston engine at higher altitudes. A turbocharged piston engine, with compressed air intake, will lose less power at altitude than an normally aspirated piston engine. A turbine engine will lose even less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a rough example, a normally aspirated Cirrus SR-22 has a service ceiling of 17,500 ft. A turbocharged SR-22 has a ceiling of 25,000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A turbocharged piston Piper Malibu Mirage has a service ceiling of 25,000 ft., while the turbine powered Malibu Meridian has a ceiling of 30,000 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turboprop Pilatus PC12 and Socata TBM-850 have service ceilings of 30,000 ft. or above.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-22T02:19:04.047" LastActivityDate="2013-12-22T02:19:04.047" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="251" PostTypeId="2" ParentId="248" CreationDate="2013-12-21T18:47:04.227" Score="2" Body="&lt;p&gt;Perhaps trivial, but your landing weight will be higher than during a standard run sans skydivers, which will have an impact on stall speed, landing distance etc.&lt;/p&gt;&#xA;" OwnerUserId="95" LastActivityDate="2013-12-21T18:47:04.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="252" PostTypeId="2" ParentId="246" CreationDate="2013-12-21T19:13:08.787" Score="13" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/NOTAR&quot;&gt;https://en.wikipedia.org/wiki/NOTAR&lt;/a&gt; the NOTAR fan is driven by the main rotor transmission. This will ensure maneuverability during autorotation.&lt;/p&gt;&#xA;" OwnerUserId="95" LastActivityDate="2013-12-21T19:13:08.787" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="253" PostTypeId="2" ParentId="240" CreationDate="2013-12-21T20:14:13.490" Score="2" Body="&lt;p&gt;Seems like the accepted practice is to use half rate when faster than 250 knots, in cruise, or when flying in icing conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0510.html&quot; rel=&quot;nofollow&quot;&gt;AIM (5-10-3)&lt;/a&gt; also states that pilots should use half standard rate (through probably referring to hand-flying) when on final of a no-gyro approach like a PAR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest of the time, in terminal areas and when holding, standard rate is expected by ATC. When unable to maintain standard rate (icing, for example) in those cases, notifying ATC should suffice. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-21T20:42:31.547" LastActivityDate="2013-12-21T20:42:31.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="254" PostTypeId="1" AcceptedAnswerId="868" CreationDate="2013-12-21T21:58:13.720" Score="21" ViewCount="7349" Body="&lt;p&gt;If a pilot uses an electronic flight bag (say, an iPad with ForeFlight or WingX), are they required to carry paper charts as a backup? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do different rules apply to operations under Parts 91, 121, and 135?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-11T21:00:13.433" LastActivityDate="2014-01-11T21:00:13.433" Title="Do pilots using an electronic flight bag need to carry paper charts?" Tags="&lt;faa-regulations&gt;&lt;aeronautical-charts&gt;&lt;equipment&gt;&lt;electronics&gt;&lt;efb&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="255" PostTypeId="2" ParentId="254" CreationDate="2013-12-21T22:02:34.507" Score="7" Body="&lt;p&gt;Typically pilots using EFBs (which need to be approved by the FAA if being used for Part 121 or 135 flights) do not need to carry paper charts if, as Steve points out, you have at least two of them.  For Part 121, 135, and 91K there is usually a six month period after gaining EFB approval when the FAA requires paper backups in addition to the EFB's as a precaution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical EFB program will have contingency procedures to use in the event of a failure or problem with one or more of the EFBs, and usually says that if one fails (and it can not be replaced or repaired) that you may not depart unless you have paper backups.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lots of other good information about EFBs is available in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1020099&quot; rel=&quot;nofollow&quot;&gt;Advisory Circular 120-76B&lt;/a&gt; and in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73540&quot; rel=&quot;nofollow&quot;&gt;Advisory Circular 91-78&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T00:34:39.357" LastActivityDate="2014-01-11T00:34:39.357" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="256" PostTypeId="1" AcceptedAnswerId="257" CreationDate="2013-12-21T22:41:32.193" Score="15" ViewCount="1735" Body="&lt;p&gt;Aircraft which have been in service for a long time often have a lot of entries in their logbooks for Airworthiness Directives (ADs). What are they, and why are they important?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2014-01-18T17:55:07.067" LastActivityDate="2020-02-01T03:21:05.543" Title="What is an Airworthiness Directive?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;aircraft-maintenance&gt;&lt;airworthiness-directive&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="257" PostTypeId="2" ParentId="256" CreationDate="2013-12-21T22:41:32.193" Score="15" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/continued_operation/ad/&quot;&gt;Straight from the FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airworthiness Directives (ADs) are legally enforceable rules issued by the FAA in accordance with 14 CFR part 39 to correct an unsafe condition in a product. 14 CFR part 39 defines a product as an aircraft, aircraft engine, propeller, or appliance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When an aircraft or other component is found to have flaws or other issues, the FAA will issue an AD specifying a solution to be applied to the item. The AD must be complied with, often by a date or total time on the airframe. The action required could simply be an inspection (often recurring after, say, 100 hours of time in service), while in other cases requires modification, strengthening, or replacement of parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the more prominent cases requiring ADs to be issued was the &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-FAA-issues-changes-to-V-tail-Bonanza-ADs.aspx&quot;&gt;V-tail Bonanza&lt;/a&gt;, which had issues with the tail's structural integrity under high loads. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost of complying with an AD falls on the owner/operator of the aircraft. &lt;strong&gt;Failing to comply with an AD renders the aircraft unairworthy&lt;/strong&gt;. It also could incur FAA penalties, but more importantly, it could result in structural damage or failure, and in some cases ultimately cause a fatal accident.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-22T05:18:17.033" LastActivityDate="2013-12-22T05:18:17.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="258" PostTypeId="1" CreationDate="2013-12-22T01:34:01.180" Score="18" ViewCount="2464" Body="&lt;p&gt;The most obvious one is fuel. Many modern military aircraft, however, are capable of refueling in mid-air. Crew fatigue, another obvious one, can also be addressed by rotating a crew out, and is a non-issue in unmanned aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question therefore is, what factors would prevent an aircraft from staying in mid-air indefinitely? Are there any such factors that cannot be addressed, and would make it impossible to design an aircraft that could stay up indefinitely, or at least for an exceptionally long time? &lt;/p&gt;&#xA;" OwnerUserId="165" LastActivityDate="2014-06-27T03:09:17.583" Title="What are the factors that limit how long an aircraft can stay aloft?" Tags="&lt;aircraft-limitations&gt;&lt;aircraft-design&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="259" PostTypeId="2" ParentId="258" CreationDate="2013-12-22T02:59:39.570" Score="15" Body="&lt;p&gt;Maintenance is probably the biggest issue. What types of maintenance is needed and the failures that not performing those steps will lead to depends on the design of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, on a piston engine used in a small aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine will need oil replaced at some point, and unless a system was created to cycle in new oil in-flight this is probably the first thing that will break down after crew and fuel (as you mentioned). Oil breaking down will lead to early failure of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel and air filters will get clogged, leading to the engine shutting down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which leads to engine wear. Eventually piston rings, ignition systems, etc. will wear out.&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2013-12-22T02:59:39.570" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="260" PostTypeId="2" ParentId="40" CreationDate="2013-12-22T03:22:18.927" Score="6" Body="&lt;p&gt;The single biggest difference is that FAR 25 has rules that pertain to wet runways. Aside from that, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11&amp;amp;rgn=div5#14:1.0.1.3.11.2.155.12&quot; rel=&quot;nofollow&quot;&gt;FAR 25.113(a)&lt;/a&gt; uses the greater of two tests to determine accelerate-stop distance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(1) Accelerate to $V_{EF}$, then reject the takeoff&lt;/li&gt;&#xA;&lt;li&gt;(2) Accelerate to the highest speed required for takeoff (somewhat unclear?), then reject the takeoff&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;...while &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.10&amp;amp;rgn=div5#14:1.0.1.3.10.2.60.11&quot; rel=&quot;nofollow&quot;&gt;23.55(a)&lt;/a&gt; is more or less equivalent to 25.113(a)(1).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing the three methods, the rules are &lt;em&gt;mostly&lt;/em&gt; comparable. The only major difference is that under Part 25 &lt;em&gt;&quot;a distance equivalent to 2 seconds at the $V_1$ for takeoff from a dry runway&quot;&lt;/em&gt; (25.113a.1.iv and 25.113a.2.iii) must be added to the other factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because aircraft certified under Part 25 must use the greater of two different tests &lt;strong&gt;and&lt;/strong&gt; add a distance equivalent to 2 seconds at $V_1$, accelerate-stop distances will likely be greater than for Part 23-certified designs that are otherwise similar.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For reference:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.10&amp;amp;rgn=div5#14:1.0.1.3.10.2.60.11&quot; rel=&quot;nofollow&quot;&gt;FAR 23.55(a)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11&amp;amp;rgn=div5#14:1.0.1.3.11.2.155.12&quot; rel=&quot;nofollow&quot;&gt;FAR 25.113(a)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="39" LastEditorUserId="97" LastEditDate="2014-04-16T23:55:48.740" LastActivityDate="2014-04-16T23:55:48.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="261" PostTypeId="5" CreationDate="2013-12-22T03:38:28.340" Score="0" Body="&lt;p&gt;The Federal Aviation Regulations (FARs), officially a part of Title 14 of the United States' Code of Federal Regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FARs contain rules pertaining to everything aviation-related: pilots, aircraft, maintenance, flight training, airlines and other commercial operations, the marking of obstacles and buildings... the list goes on. Wikipedia has a very &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Aviation_Regulations&quot; rel=&quot;nofollow&quot;&gt;thorough description&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specific areas of the FARs with their own tags include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-91&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-91&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-91&lt;/a&gt; Part 91 - General flight and operating rules&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-135&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-135&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-135&lt;/a&gt; Part 135 - Operating Requirements: Commuter and On Demand Operations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="39" LastEditorUserId="64" LastEditDate="2013-12-30T21:52:42.383" LastActivityDate="2013-12-30T21:52:42.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="262" PostTypeId="4" CreationDate="2013-12-22T03:38:28.340" Score="0" Body="The Federal Aviation Regulations (FARs) are the aviation rules of the United States of America." OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-22T18:34:09.603" LastActivityDate="2013-12-22T18:34:09.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="263" PostTypeId="1" AcceptedAnswerId="1225" CreationDate="2013-12-22T04:53:08.523" Score="12" ViewCount="4424" Body="&lt;p&gt;What restrictions are there on a flight in international airspace? For example, if you fly into the Pacific Ocean more than 12 miles (or whatever the distance is) offshore, are you free to fly any speed (such as faster than sound), at any altitude, or in any weather? Are FAA regulations in effect? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is anybody really &quot;in charge&quot; of this airspace? If not, how do airliners keep organized on intercontinental flights?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="69" LastEditDate="2014-01-18T18:03:55.277" LastActivityDate="2014-01-21T23:41:58.110" Title="What restrictions apply in international airspace?" Tags="&lt;faa-regulations&gt;&lt;international&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="264" PostTypeId="2" ParentId="258" CreationDate="2013-12-22T05:08:24.417" Score="14" Body="&lt;h2&gt;The pilot.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Seriously. You're it.&lt;br&gt;&#xA;For the sake of (absurdist) argument, let's say we build something akin to a &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_U-2&quot;&gt;U-2&lt;/a&gt; out of ultra-strong, super-lightweight composites - let's make it a pure glider (it's close enough anyway, and now we have no engine or anything to get in the way and fail!), and we'll use only the best-traied factory capuchin monkeys to ensure a perfect assembly so all the parts do their job exactly per design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We've got a million-plus-hour glider, and we just dropped a &lt;s&gt;hapless victim&lt;/s&gt; volunteer pilot off at say 50,000 feet with a top-secret life support system that's going to give them heat, air, water, a nice steak dinner every night, and even take care of that odd human desire not to sit in our own waste products.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could - in this theoretical wonderplane, ride air currents, thermals, storm updrafts (for the crazy), etc. and stay aloft pretty much indefinitely, but eventually our volunteer is going to get sick of steak, or start getting bed sores/blood clots/cramps from the seat, or just plain get sick of looking for that next updraft to keep the glider aloft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we make the whole thing remote controlled with a wind-turbine generator to power the controls we could swap out pilots and possibly keep it going for years, but it's not much of an &quot;airplane&quot; if there's nobody flying it -- just another drone.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ultimately every other factor you can come up with is going to be subordinate to the endurance of the humans on board - as a lot of the GA pilots I hang out with are fond of pointing out many of us fly in aircraft easily have 4-5 hours of fuel endurance, but most of us only have a 2-3 hour bladder (and no magic steak-serving life support machine. Gotta buy me one of those for Christmas...).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-22T05:08:24.417" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="265" PostTypeId="1" CreationDate="2013-12-22T05:16:24.773" Score="14" ViewCount="27284" Body="&lt;p&gt;Is there a method by which the conversions can be achieved on the fly by using a mathematical formulae and not using specific area charts?&lt;/p&gt;&#xA;" OwnerUserId="166" LastEditorUserId="14897" LastEditDate="2021-03-27T02:27:18.147" LastActivityDate="2021-04-12T10:19:56.013" Title="How do I convert true heading to magnetic heading or the other way around?" Tags="&lt;navigation&gt;&lt;heading&gt;&lt;magnetic-compass&gt;&lt;magnetic-variation&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="266" PostTypeId="5" CreationDate="2013-12-22T05:27:58.780" Score="0" Body="&lt;p&gt;Part 91 of the US Federal Air Regulations deals with general operating rules for civil aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains regulatory requirements pertaining to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2&quot; rel=&quot;nofollow&quot;&gt;flight rules&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.3&quot; rel=&quot;nofollow&quot;&gt;equipment, instrument and certification requirements&lt;/a&gt;, and other requirements applicable to all flights conducted in US airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14&quot; rel=&quot;nofollow&quot;&gt;The full text of FAR 91 can be found online, as 14 CFR 91&lt;/a&gt;, as well as in printed form at most pilot shops.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:35:06.280" LastActivityDate="2013-12-22T18:35:06.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="267" PostTypeId="4" CreationDate="2013-12-22T05:27:58.780" Score="0" Body="Part 91 of the US Federal Air Regulations (FARs) deals with general operating rules for civil aircraft. " OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:32:59.207" LastActivityDate="2013-12-22T18:32:59.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="268" PostTypeId="5" CreationDate="2013-12-22T05:36:30.010" Score="0" Body="&lt;p&gt;Part 135 of the US Federal Air Regulations deals with &quot;Commuter and On-Demand&quot; commercial aircraft operations, such as sightseeing tours and charter flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This section contains requirements &lt;em&gt;in addition to&lt;/em&gt; those under &lt;a href=&quot;/questions/tagged/far-91&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-91&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-91&lt;/a&gt;, such as &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=6e070b45eab4d2b5d4ba63e9155161f7&amp;amp;node=14:3.0.1.1.11.3&amp;amp;rgn=div6&quot; rel=&quot;nofollow&quot;&gt;specific additional equipment that must be present on the aircraft&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=6e070b45eab4d2b5d4ba63e9155161f7&amp;amp;node=14:3.0.1.1.11.5&amp;amp;rgn=div6&quot; rel=&quot;nofollow&quot;&gt;additional flight crew qualifications&lt;/a&gt;, and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=6e070b45eab4d2b5d4ba63e9155161f7&amp;amp;node=14:3.0.1.1.11.10&amp;amp;rgn=div6&quot; rel=&quot;nofollow&quot;&gt;additional maintenance-related stipulations&lt;/a&gt; which carriers operating under part 135 are required to comply with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;tpl=/ecfrbrowse/Title14/14cfr135_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;The full text of FAR 135 is available online as 14 CFR 135&lt;/a&gt;, as well as in printed form at most pilot shops.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:35:38.347" LastActivityDate="2013-12-22T18:35:38.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="269" PostTypeId="4" CreationDate="2013-12-22T05:36:30.010" Score="0" Body="Part 135 of the US Federal Air Regulations deals with &quot;commuter and on-demand&quot; commercial aircraft operations - for example, sightseeing tours and charter flights." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:34:03.260" LastActivityDate="2013-12-22T18:34:03.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="270" PostTypeId="5" CreationDate="2013-12-22T05:48:36.867" Score="0" Body="&lt;p&gt;The CG (Center of Gravity) of aircraft is the point at which the aircraft would balance if it were possible to suspend it at that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The center of gravity is affected by the aircraft's loading (fuel, passengers, baggage, etc.), and is the &quot;balance&quot; portion of the &lt;a href=&quot;/questions/tagged/weight-and-balance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;weight-and-balance&amp;#39;&quot; rel=&quot;tag&quot;&gt;weight-and-balance&lt;/a&gt; calculations performed prior to flight. In order to ensure safety of flight the center of gravity must lie within a predetermined range specified by the manufacturer. Operation of the aircraft with the center of gravity outside of this range can result in severe difficulty controlling the aircraft, and ultimately lead to an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For additional information on Center of Gravity and its importance to flight refer to the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Center_of_gravity_of_an_aircraft&quot; rel=&quot;nofollow&quot;&gt;Wikipedia: Center of Gravity of an Aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/faa-h-8083-1a.pdf&quot; rel=&quot;nofollow&quot;&gt;The FAA Aircraft Weight &amp;amp; Balance Handbook&lt;/a&gt; (FAA-H-8083-1a), specifically Chapter 2.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:34:22.387" LastActivityDate="2013-12-22T18:34:22.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="271" PostTypeId="4" CreationDate="2013-12-22T05:48:36.867" Score="0" Body="The CG (Center of Gravity) of aircraft is the point at which the aircraft would balance if it were possible to suspend it at that point." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-22T18:33:14.207" LastActivityDate="2013-12-22T18:33:14.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="272" PostTypeId="1" CreationDate="2013-12-22T06:04:29.310" Score="4" ViewCount="176" Body="&lt;p&gt;The Boeing 737 flew for several years despite &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_rudder_issues&quot; rel=&quot;nofollow&quot;&gt;rudder issues&lt;/a&gt; which had not been fully understood and resolved. It's conceivable that flyers who avoided the aircraft had had less probability of injury or death while flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does one identify which aircraft are &lt;em&gt;currently&lt;/em&gt; under some sort of investigation for similar, on-going issues?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="5517" LastEditDate="2016-03-01T20:43:14.803" LastActivityDate="2016-03-01T20:43:14.803" Title="How to determine if an aircraft type is currently under investigation?" Tags="&lt;aircraft-failure&gt;&lt;accidents&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="273" PostTypeId="2" ParentId="265" CreationDate="2013-12-22T06:17:25.197" Score="18" Body="&lt;p&gt;Short answer: &lt;a href=&quot;http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html&quot; rel=&quot;noreferrer&quot;&gt;Yes there is, but it doesn't always work, it involves a &lt;em&gt;LOT&lt;/em&gt; of math, and you're probably not gonna like it.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Medium Answer: Most flight planning software incorporates a True/Magnetic heading conversion system (&lt;a href=&quot;http://www.foreflight.com&quot; rel=&quot;noreferrer&quot;&gt;ForeFlight&lt;/a&gt; for example).&lt;br /&gt;&#xA;Using an electronic flight planning tool like this is probably your best bet if you want an on-the-fly determination made for you.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Long answer:&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/International_Association_of_Geomagnetism_and_Aeronomy&quot; rel=&quot;noreferrer&quot;&gt;International Association of Geomagnetism and Aeronomy&lt;/a&gt; (now there's a mouthful!) periodically publishes what's known as &amp;quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/International_Geomagnetic_Reference_Field&quot; rel=&quot;noreferrer&quot;&gt;International Geomagnetic Reference Field (IGRF)&lt;/a&gt;&amp;quot;.  It's a mathematical model of Earth's geomagnetic field, which you can work from some &lt;em&gt;exceptionally&lt;/em&gt; complicated trigonometry (or just look up the coefficients in a table which is what most sane folks do).&lt;/p&gt;&#xA;&lt;p&gt;If reading text like &amp;quot;Mathematically, the IGRF model consists of the Gauss coefficients which define a spherical harmonic expansion of the magnetic scalar potential.&amp;quot; makes your eyes roll back into your head (I was a math nerd and it makes &lt;em&gt;&lt;strong&gt;MINE&lt;/strong&gt;&lt;/em&gt; roll back!) using the model is probably not for you.&lt;br /&gt;&#xA;If your eyes are still focused on this text however, click on through to that link way back at the top of my answer and you'll be rewarded with a formula you can plug into your trusty calculator.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-23T22:23:26.177" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="274" PostTypeId="2" ParentId="272" CreationDate="2013-12-22T07:36:28.633" Score="3" Body="&lt;p&gt;All aircraft are constantly under investigation. Service bulletins and airworthiness directives are issued for every certified plane and engine. These are optional and mandatory checks and maintenance to be done in additional to the normally scheduled maintenance. Every accident and important incident is investigated by the NTSB, with a &lt;a href=&quot;http://www.ntsb.gov/aviationquery/&quot; rel=&quot;nofollow&quot;&gt;public report&lt;/a&gt; available online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a period of time before an airworthiness directive is made final that might be considered an investigative phase, but information on this is generally not publicly available. One &lt;a href=&quot;http://www.usatoday.com/story/travel/flights/2012/11/19/airbus-rudder/1707421/&quot; rel=&quot;nofollow&quot;&gt;notable example&lt;/a&gt; pertains to the rudder controls on the Airbus A-300.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-22T07:36:28.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="275" PostTypeId="1" AcceptedAnswerId="276" CreationDate="2013-12-22T07:47:12.450" Score="19" ViewCount="8399" Body="&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=6mbIRXnCSts&quot;&gt;This video&lt;/a&gt; shows a Hawker jet with the wing fluttering up and down like it's about to break. What can cause flutter like that? Can it actually cause a wing or stabilizer failure? How can flutter be prevented? What should be done if something like this happens?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="97" LastEditDate="2014-01-13T02:03:41.820" LastActivityDate="2015-05-20T08:26:55.557" Title="What causes aileron and elevator flutter?" Tags="&lt;aerodynamics&gt;&lt;flutter&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="276" PostTypeId="2" ParentId="275" CreationDate="2013-12-22T08:17:58.723" Score="14" Body="&lt;p&gt;Imbalanced or loose (and, in extreme cases, &lt;a href=&quot;http://www.ntsb.gov/news/events/Pages/2012_Reno_NV_BMG.aspx&quot; rel=&quot;nofollow&quot;&gt;structurally weak&lt;/a&gt;) control surfaces can cause flutter, &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroelastic_flutter#Flutter&quot; rel=&quot;nofollow&quot;&gt;a type of harmonic motion&lt;/a&gt;. Flutter is a very dangerous condition; if it is not stopped, it can cause structural failure and potentially lead to a fatal accident. V-tail Bonanzas had a series of such accidents related to flutter of the butterfly ruddervator tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that prevention is a combination of good maintenance and keeping the aircraft below Vne (never exceed speed), or possibly other speeds in some configurations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The appropriate reaction would be to slow down, first and foremost. Descending is probably also a wise choice.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="19" LastEditDate="2015-05-20T08:26:55.557" LastActivityDate="2015-05-20T08:26:55.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="277" PostTypeId="2" ParentId="198" CreationDate="2013-12-22T09:34:49.003" Score="46" Body="&lt;p&gt;Since Geoff took the devil's advocate position, I'll play cheerleader.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the statistics another way, like &lt;a href=&quot;http://www.aopa.org/letsgoflying/stories/080829safety.html&quot;&gt;AOPA does&lt;/a&gt;, you'll find that General Aviation has &quot;about one-sixth as many accidents on a per-vehicle-mile basis&quot; compared to driving.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or to put it another way I'm 6 times more likely to get in a car accident driving to the airport as I am doing an equivalent number of miles puttering around in the pattern (my drive isn't that far - it's only worth a few laps around the pattern).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So now I've gone and left you with two essentially contradictory answers, both based on statistics from the same source, and both equally valid from a cold, unfeeling, numerical standpoint. But the answer isn't important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Geoff and I are both really making the same point:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Each flight is as safe as the pilot wants to make it.&lt;/strong&gt;  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilot comes up with a plan for the flight, gathers as much information as they can about the weather, the aircraft, the route, etc., and then assess the situation.&lt;br&gt;&#xA;They weigh the risks and determine whether or not the level of risk in making that flight is &lt;em&gt;acceptable&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The statistics are useful. Most pilots I know spend a lot of time thinking about them (mainly why they're so lousy, and how we can make them better), but as a passenger remember they lump in the professionals with the students, and the conscientious pilot doing a thorough preflight with the one who haphazardly kicks the tire as he's climbing in for a 500 mile trip as his first flight in 6 months.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which kind of pilot are &lt;strong&gt;&lt;em&gt;you&lt;/em&gt;&lt;/strong&gt; flying with?  &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-22T09:34:49.003" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="279" PostTypeId="1" AcceptedAnswerId="288" CreationDate="2013-12-22T15:57:58.437" Score="27" ViewCount="17482" Body="&lt;p&gt;AIM 4-4-7 (b) says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots of airborne aircraft should read back those parts of ATC&#xA;  clearances and instructions containing altitude assignments, vectors,&#xA;  or runway assignments as a means of mutual verification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a student pilot soloing into class C airspace, on one flight ATC kept repeating everything back until I spoke it back to him. As I approached the airport he informed me of the bearing (12 o'clock) and distance to the airport until I acknowledged him (comms were pretty busy so I didn't initially repeat back his information).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since then I've noticed that if I don't repeat back wake turbulence warnings verbatim they will repeat the warning until I do. With a traffic alert I repeat back immediately 'looking for traffic' because if I look first they'll keep repeating the warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from AIM 4-4-7 is there any more specific guidance?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="69" LastEditDate="2013-12-25T04:14:16.510" LastActivityDate="2021-02-09T00:58:53.747" Title="Which ATC instructions should be repeated back by the pilot?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;aim&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="280" PostTypeId="1" CreationDate="2013-12-22T17:09:56.677" Score="10" ViewCount="3301" Body="&lt;p&gt;China recently caused some controversy by announcing an Air Defense Identification Zone (ADIZ) in the &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/c/c9/JADIZ_and_CADIZ_and_KADIZ_in_East_China_Sea.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;East China Sea&lt;/a&gt;. There is also an ADIZ surrounding &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/en/4/46/ADIZ_Boundaries.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;most of North America.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is an ADIZ and what does it take to fly across one? For example, what would be necessary to fly a private plane directly from Apalachicola to Cedar Key, Florida?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gon6T.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="923" LastEditDate="2015-04-16T03:42:55.400" LastActivityDate="2015-04-16T03:42:55.400" Title="What is an Air Defense Identification Zone (ADIZ)?" Tags="&lt;airspace&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="281" PostTypeId="1" AcceptedAnswerId="284" CreationDate="2013-12-22T17:20:18.260" Score="22" ViewCount="2264" Body="&lt;p&gt;Is it legal for planes to takeoff and land in zero visibility? Is it safe?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="1696" LastEditDate="2015-02-11T23:22:07.487" LastActivityDate="2015-02-11T23:22:07.487" Title="Is it legal and safe to take off or land in zero visibility?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="282" PostTypeId="2" ParentId="279" CreationDate="2013-12-22T17:41:37.060" Score="13" Body="&lt;p&gt;This little quote from the AIM is the source of a lot of confusion for new pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html&quot; rel=&quot;noreferrer&quot;&gt;4-2-3&lt;/a&gt; (c), the AIM also says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;c. Subsequent Contacts and Responses to Callup from a Ground Facility.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;You should acknowledge all callups or clearances&lt;/em&gt; unless the controller&#xA;  or FSS specialist advises otherwise.&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  Acknowledge with your aircraft identification, either at the beginning&#xA;  or at the end of your transmission, and one of the words &quot;Wilco,&quot;&#xA;  &quot;Roger,&quot; &quot;Affirmative,&quot; &quot;Negative,&quot; or other appropriate remarks;&#xA;  e.g., &quot;PIPER TWO ONE FOUR LIMA, ROGER.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Let me make it simple:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You should &lt;strong&gt;read back&lt;/strong&gt; those items that the AIM 4-4-7 specifies (and that you quoted in your question).  Basically any time that they give you a clearance or anything that contains a number.&lt;/li&gt;&#xA;&lt;li&gt;You should &lt;strong&gt;acknowledge&lt;/strong&gt; with at the bare minimum your aircraft call sign and preferably something that lets them know that you got their instructions/message and understand it, &lt;strong&gt;every&lt;/strong&gt; time that ATC talks to you.&lt;br&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The one exception is after you have been handed off to the final controller on a PAR approach, you do not acknowledge their instructions.  They come too fast and you will have your hands full (and they specifically tell you this after your initial contact.)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a short aside, you should know that there is case law which says that even when a pilot reads back a clearance incorrectly, the controller is not &lt;em&gt;legally obligated&lt;/em&gt; to listen or correct the pilot.  They consider it the pilot responsibility to hear and understand all clearances.  For instance:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Controller: Cessna 1234, descend and maintain 3,000 feet&lt;br&gt;&#xA;  Pilot: Cessna 1234, Roger, descend and maintain 2,000 feet&lt;br&gt;&#xA;  Controller: No response&lt;br&gt;&#xA;  Pilot: Descends to 2,000 feet because that is what he understood, and&#xA;  may now be violated for it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, most controllers are very good and catch mistakes like this that you may make, but I have heard conversations in the cockpit along the lines of &quot;it must be right because they didn't correct me when I read it back&quot; and this is a situation ripe for problems/violations.  If there is &lt;strong&gt;&lt;em&gt;ever&lt;/em&gt;&lt;/strong&gt; a doubt, ask for clarification!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-20T09:16:00.307" LastActivityDate="2014-02-20T09:16:00.307" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="283" PostTypeId="2" ParentId="280" CreationDate="2013-12-22T17:52:34.517" Score="10" Body="&lt;h1&gt;What is an ADIZ?&lt;/h1&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/CEA2B0DB41194679862571650050EB78?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 99.3&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Air defense identification zone (ADIZ) means an area of airspace over land or water in which the ready identification, location, and control of all aircraft (except for Department of Defense and law enforcement aircraft) is required in the interest of national security.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;To put it simply, if you're going to fly in the United States ADIZ, the United States government wants to know:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Who&lt;/strong&gt; you are&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Where&lt;/strong&gt; you are&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;What&lt;/strong&gt; you're doing&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;What do I need to have before I fly through one?&lt;/h1&gt;&#xA;&lt;p&gt;A few things, actually.  They're listed in &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 5-6-1&lt;/a&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You generally need to &lt;strong&gt;file a flight plan&lt;/strong&gt; (but there are exceptions). (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/73465F95F99CF294862571650050EDD2?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 99.11&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;You need a &lt;strong&gt;two-way radio&lt;/strong&gt;. (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/73DB8EF69BBF6171862571650050ED42?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 99.9(a)&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;You need to have a &lt;strong&gt;Mode C transponder&lt;/strong&gt;, and it has to be on. (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/06E2A6F0D3DDA649862571650050EEEE?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 99.13&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;If you're going DVFR (rather than IFR), you need to give an &lt;strong&gt;estimated time&lt;/strong&gt; of ADIZ penetration at least 15 minutes before entering it. (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/73A99B851D6EBCB9862571650050EF7C?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 99.15&lt;/a&gt;, also reference &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 5-6-1.4b&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;What do I need to do while I'm in one?&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Remain no more than &lt;strong&gt;5 minutes&lt;/strong&gt; off the proposed ETA to your various waypoints&lt;/li&gt;&#xA;&lt;li&gt;Remain no more than:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;10 miles&lt;/strong&gt; from the centerline of your route, if over land&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;20 miles&lt;/strong&gt; from the centerline of your route, if over water&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2013-12-22T17:52:34.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="284" PostTypeId="2" ParentId="281" CreationDate="2013-12-22T18:39:45.980" Score="17" Body="&lt;p&gt;In the US, for general aviation flights, operating under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=3efaad1b0a259d4e48f1150a34d1aa77&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14&quot;&gt;Part 91 of the FARs&lt;/a&gt;, it is legal to take off with zero visibility (&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/CH-02.pdf&quot;&gt;see page 2-2 of the IPH&lt;/a&gt;, PDF). In my opinion, &lt;strong&gt;it is not safe.&lt;/strong&gt; If an emergency were to take place, you would be unable to return and land; under Part 91, it is &lt;em&gt;not&lt;/em&gt; legal to land unless conditions are equal to or better than a runway's published approach minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless you've got a great alternate nearby, conditions are improving rapidly, or you've got an extra engine or two, you probably shouldn't take off in conditions you couldn't land in. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-22T19:36:33.393" LastActivityDate="2013-12-22T19:36:33.393" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="285" PostTypeId="2" ParentId="263" CreationDate="2013-12-22T19:20:00.837" Score="2" Body="&lt;p&gt;The relevant FAA information is available &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/oceanic_remote/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. As the page says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The dynamics of oceanic and remote international operations are such&#xA;  that they are constantly evolving and it is incumbent upon the&#xA;  operators to closely monitor any changes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The general approach as I very roughly understand it is that ICAO defines general procedures, airspace etc. for international airspace but each country is responsible for ensuring that their aircraft comply, so if - for example - you want to cross the North Atlantic in an N-registered aircraft then you require FAA approval.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.paris.icao.int/documents_open/show_file.php?id=606&quot; rel=&quot;nofollow&quot;&gt;North Atlantic Operations and Airspace Manual&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Within this airspace a formal Approval Process by the State of&#xA;  Registry of the aircraft or the State of the Operator ensures that&#xA;  aircraft meet defined MNPS Standards and that appropriate crew&#xA;  procedures and training have been adopted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The document does acknowledge that it's mainly aimed at airlines but it also states that it applies to GA flights too:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft without NAT MNPS or RVSM Approvals may, of course, also fly&#xA;  across the North Atlantic below FL285. However, due consideration must&#xA;  be given to the particular operating environment. Especially by&#xA;  pilots/operators of single and twin engine aircraft. Weather&#xA;  conditions can be harsh; there are limited VHF radio communications&#xA;  and ground-based navigation aids; and the terrain can be rugged and&#xA;  sparsely populated. International General Aviation (IGA) flights at&#xA;  these lower levels constitute a very small percentage of the overall&#xA;  NAT traffic but they account for the vast majority of Search and&#xA;  Rescue operations. Specific guidance for the pilots and operators of&#xA;  such flights was previously contained in the North Atlantic&#xA;  International General Aviation (NAT IGA) Operations Manual published&#xA;  by the FAA on behalf of the ICAO North Atlantic Systems Planning Group&#xA;  (NAT SPG). However, with effect from this Edition 2013, such guidance&#xA;  has been subsumed into this document.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-22T19:20:00.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="286" PostTypeId="2" ParentId="279" CreationDate="2013-12-22T19:49:31.633" Score="9" Body="&lt;p&gt;Regardless of what the AIM says, the practical rule I've always been taught is &quot;read back all instructions&quot;. In other words, if ATC is telling you to do something then you must read it back otherwise they have no way to know if you understood the instruction correctly and will do what they expect you to. This includes clearance, ground and airborne instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC information on the other hand is not an instruction (e.g. traffic advisories) so you only need to acknowledge it. But you should also read back altimeter settings because they're essential for maintaining altitude and therefore separation correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And ATC is often very good at giving student pilots extra attention so even if they wouldn't expect a readback in other circumstances, they may have made an extra effort in the case you mentioned to make sure there was no possible misunderstanding.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-22T19:49:31.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="287" PostTypeId="1" AcceptedAnswerId="291" CreationDate="2013-12-22T20:09:10.487" Score="22" ViewCount="5776" Body="&lt;p&gt;Many pilots who are not native English speakers have a hard time when they start flying in the U.S. because of the pace and sometimes elaborate instructions given to pilots by controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advice given by instructors is to tell the controller that you're a student pilot, even though you may be a fully licensed (private) pilot. The effect should be that the controller will be more lenient towards the pilot and speak slower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would first of all like to know if it is legal to tell a controller that you're a student pilot even if you're not (I know, all pilots should see themselves as students for the rest of their life, but that's another topic). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, isn't there a chance that you'd get refused entry in class B airspace because you're announcing that you're a student pilot?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="572" LastEditDate="2015-02-19T10:07:22.567" LastActivityDate="2017-06-19T20:57:55.913" Title="Can you tell ATC you are a &quot;student pilot&quot; when you are not?" Tags="&lt;air-traffic-control&gt;&lt;student-pilot&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="288" PostTypeId="2" ParentId="279" CreationDate="2013-12-22T20:19:12.453" Score="32" Body="&lt;p&gt;ATC is, broadly speaking, required to ensure that pilots hear, understand, and acknowledge information that is delivered.  The way they do that is via read-backs, and although the AIM mentions a few of the things that are required it's a good idea to read back &lt;em&gt;anything that's important&lt;/em&gt; (If you're not sure, err on the side of &quot;It's important&quot;), with your aircraft callsign (No callsign? Doesn't count!). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some important things controllers usually expect you to read back?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Clearances (headings, vectors, altitudes, transponder codes, and radio frequencies).&lt;/strong&gt;&lt;br&gt;&#xA;Like the AIM says, mutual verification.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Runway assignments, hold short instructions, line-up-and-wait, and takeoff clearances.&lt;/strong&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Taxi routes Instructions, &lt;em&gt;ESPECIALLY&lt;/em&gt; runway crossings &amp;amp; hold-short instructions.&lt;/strong&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Wake Turbulence advisories.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Traffic point-outs.&lt;/strong&gt;&lt;br&gt;&#xA;The magic words here, by the by, are &quot;&lt;em&gt;Negative Contact&lt;/em&gt;&quot; and &quot;&lt;em&gt;Traffic In Sight&lt;/em&gt;&quot;.&lt;br&gt;&#xA;&lt;sup&gt;I think if you say &quot;Tally Ho!&quot; you're required to buy everyone on the frequency a bottle of 30-year-old scotch.&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Instructions to &quot;&lt;em&gt;Maintain visual separation with&lt;/em&gt;&quot; some traffic&lt;/strong&gt;&lt;br&gt;&#xA;ATC is handing off collision avoidance responsibility to you as the pilot.&lt;br&gt;&#xA;They need to hear &quot;&lt;em&gt;Will maintain visual separation with&lt;/em&gt;&quot; the traffic in question.&lt;br&gt;&#xA;&lt;em&gt;They also need you to tell them if you lose visual contact.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Airport Point-Outs&lt;/strong&gt; (Especially if there are several airports close to each other)&lt;br&gt;&#xA;You can also pre-empt this by calling the controller: &quot;Cessna 12345 has Podunk Municipal in sight&quot;, possibly with a bearing and approximate distance.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Landing Clearances&lt;/strong&gt;&lt;br&gt;&#xA;If you're in a busy pattern and they give you a sequence (&quot;Number 3, cleared to land&quot;) they want to hear that part too.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;That altimeter setting you get after a handoff.&lt;/strong&gt;&lt;br&gt;&#xA;(I blame &lt;a href=&quot;http://www.avweb.com/news/sayagain/183139-1.html?redirected=1&quot; rel=&quot;noreferrer&quot;&gt;Don Brown&lt;/a&gt; for getting me into this habit, but it IS a good one unless the frequency is crazy)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This list is by no means exhaustive, but it's most of the big stuff.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2016-02-25T04:31:11.280" LastActivityDate="2016-02-25T04:31:11.280" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="289" PostTypeId="2" ParentId="287" CreationDate="2013-12-22T20:26:35.913" Score="4" Body="&lt;p&gt;An experienced ATC controller giving my flying club a presentation suggested that as you said, we're all students, since we are always learning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;His recommendation is to say 'student pilot' whenever we feel like we need extra patience and clarity regardless of how long we've had our PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, I wouldn't over use it unless I really felt like I needed some extra patience, especially in a class B.&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2013-12-22T20:26:35.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="290" PostTypeId="2" ParentId="287" CreationDate="2013-12-22T20:52:40.510" Score="7" Body="&lt;p&gt;Is it legal? Sure.  As others have pointed out it's also pretty darn honest!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a private pilot. I'm also a student pilot, working on my instrument rating.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I'm done with that I'll probably work on a complex endorsement and a commercial rating, maybe even a CFI if I get ambitious, and a tailwheel endorsement is on my list.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I can find a rich benefactor to pay for it a multi-engine rating or even a seaplane rating would be fun to pursue. And I'll sell my soul for a DC-3 type rating. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if I collect all the ratings I want I would still go up every month or so with an instructor just to kick around and drill stuff that I wouldn't normally do, and I work through phases of the &lt;a href=&quot;https://www.faasafety.gov/WINGS/pppinfo/&quot; rel=&quot;noreferrer&quot;&gt;FAA WINGS program&lt;/a&gt;, which is certainly designed as a training/learning experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Might a controller deny you clearance into specific airspace if you tell them you're a student? Sure.&lt;br&gt;&#xA;But they might deny you the clearance anyway - maybe they're busy, or maybe they're just in a bad mood.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Does it matter?&lt;br&gt;&#xA;I don't think so. I identified myself as a student pilot &lt;em&gt;maybe&lt;/em&gt; five times in my flight training, all while doing required &quot;supervised solo&quot; work at the local airport.&lt;br&gt;&#xA;In my case I've always been comfortable with radio communication, so it wasn't an issue from that standpoint, and I've never felt that I needed any &quot;extra patience&quot; from ATC - they tend to be a very patient lot, even when I screw up (a few legendary local grouches aside).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/S0Ixl.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S0Ixlm.png&quot; alt=&quot;On the ATC Frequency, no one knows you&amp;#39;re a dog...er, student&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-22T20:52:40.510" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="291" PostTypeId="2" ParentId="287" CreationDate="2013-12-22T22:36:43.347" Score="40" Body="&lt;p&gt;It's a bad idea to give false information to a controller as a matter of practice. Instead of calling yourself a student when you're not, it would be better to say you're unfamiliar with the area or that your English is not perfect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers are almost always accommodating to less-than-proficient pilots and will usually make allowances whenever time and traffic permits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your English is not good, be sure and use simple, direct phraseology. Read the AIM to become familiar with the common phrases used with ATC. Even something as simple as hearing &quot;radar identified&quot; in Canada instead of the usual U.S. phrase &quot;radar contact&quot; has caused many a native English speaker to reply &quot;say again?&quot;&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-22T22:36:43.347" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="292" PostTypeId="1" AcceptedAnswerId="300" CreationDate="2013-12-22T23:32:39.487" Score="16" ViewCount="5149" Body="&lt;p&gt;When should a transponder be turned turn on?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;On the ground?&lt;/li&gt;&#xA;&lt;li&gt;Always in flight?&lt;/li&gt;&#xA;&lt;li&gt;Only when required: during radar service (flight following), above 10,000ft MSL, inside the Mode C Veil, or on IFR flight?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Should Altitude Mode be used whenever the transpoder is on?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="1696" LastEditDate="2018-04-20T19:40:57.963" LastActivityDate="2018-04-20T19:40:57.963" Title="When should a transponder be used?" Tags="&lt;avionics&gt;&lt;transponder&gt;&lt;aircraft-operations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="293" PostTypeId="1" AcceptedAnswerId="297" CreationDate="2013-12-22T23:35:35.843" Score="7" ViewCount="571" Body="&lt;p&gt;Is there a way to make sure a flight is tracked on &lt;a href=&quot;http://flightaware.com&quot; rel=&quot;nofollow&quot;&gt;flightaware.com&lt;/a&gt; or similar sites?&lt;br&gt;&#xA;Similarly, is there a way to &lt;em&gt;prevent&lt;/em&gt; a flight's track from being available to the public?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="1696" LastEditDate="2018-04-20T19:40:36.777" LastActivityDate="2018-04-20T19:40:36.777" Title="When are flight tracks publicly available?" Tags="&lt;online-tracking&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="294" PostTypeId="1" CreationDate="2013-12-22T23:39:25.693" Score="15" ViewCount="829" Body="&lt;p&gt;Is it possible to fly internationally understanding only English for radio communications? Are there exceptions?&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="69" LastEditDate="2013-12-27T01:41:57.787" LastActivityDate="2013-12-27T01:41:57.787" Title="Is English sufficient for international aviation?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;international&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="295" PostTypeId="2" ParentId="294" CreationDate="2013-12-23T00:40:59.490" Score="6" Body="&lt;p&gt;I can only speak for Europe and the U.S. but be prepared to encounter controllers who only speak French when flying in France. As far as I know, France is the only country in Europe where English is not required for ATC. The same may be true for (former) French colonies but I don't know for sure.&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2013-12-23T00:40:59.490" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="296" PostTypeId="2" ParentId="294" CreationDate="2013-12-23T00:41:45.513" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://cfapp.icao.int/fsix/lp/docs/resolution.pdf&quot;&gt;ICAO has standardized on English&lt;/a&gt; (PDF), which &quot;urges&quot; (apparently it does not require?) contracting states (participating members) to use English for all communication. I believe proficiency standards implementation was originally set for 2008, but was &lt;a href=&quot;http://cfapp.icao.int/fsix/lp/docs/English.pdf&quot;&gt;pushed back to 2011&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exceptions to this standard would be, most likely, any country which is not &lt;a href=&quot;http://www.icao.int/about-icao/Pages/member-states.aspx&quot;&gt;an ICAO member&lt;/a&gt;. For the most part, as of now flight in ICAO member countries &lt;em&gt;should&lt;/em&gt; be possible if English is your only language, as the proficiency standards testing has been rolled out.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Personally speaking, I recently flew in Iceland, which has some &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_cities_and_towns_in_Iceland&quot;&gt;forbiddingly-hard-to-pronounce names&lt;/a&gt;, but is an ICAO member state and which uses English for everything. It was a great, low-stress experience; air traffic controllers were very understanding and knew what I meant when I attempted to pronounce place names, even if I butchered them. Which I almost certainly did.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-23T00:41:45.513" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="297" PostTypeId="2" ParentId="293" CreationDate="2013-12-23T00:51:16.470" Score="8" Body="&lt;p&gt;Skimming &lt;a href=&quot;http://flightaware.com/about/faq&quot;&gt;FlightAware's FAQs&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;ul&gt;&#xA;&lt;li&gt;The most consistent way to show up on FlightAware is to have your flight worked by ATC (a squawk code and an IFR flight plan), or to fly an airplane equipped with ADS-B Out.&lt;/li&gt;&#xA;&lt;li&gt;FlightAware &lt;a href=&quot;http://flightaware.com/about/faq#vfr&quot;&gt;doesn't really track VFR flights&lt;/a&gt; unless they have ADS-B Out:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;some VFR aircraft with flight following are available on the position maps but it largely unreliable&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  You can block your tail number &lt;a href=&quot;http://flightaware.com/about/faq#blockmytail&quot;&gt;in a few ways&lt;/a&gt;. Both the FAA and FlightAware operate block lists.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-23T00:51:16.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="299" PostTypeId="2" ParentId="293" CreationDate="2013-12-23T01:03:58.430" Score="4" Body="&lt;p&gt;Sites that track aircraft including FAA 5 minute delayed are &lt;a href=&quot;http://www.flightradar24.com&quot; rel=&quot;nofollow&quot;&gt;Flight Radar 24&lt;/a&gt; and &lt;a href=&quot;http://planefinder.net/&quot; rel=&quot;nofollow&quot;&gt;Plane Finder&lt;/a&gt; I am also putting up a private tracking network in the Philippines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These sites use volunteers that host equipment on an internet connection. Typically these sites will receive Data from Mode S Transponders from up to 200+ miles away with the right aerials. I only need about 6-8 sites to cover the whole Philippines. Line Of Sight limits below horizon reception, so you do need a station close to an airport if you want to get ground traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you emit Mode-S then you will be seen. There are no regulations to prohibit that and almost impossible to enforce.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone can create this setup for less than $30.00, so there is no point in worrying about who is seeing what.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA so have the ability to hide a specific aircraft, you can request that, but the private networks will report the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another technology called MultiLateration that can determine an aircraft's location form 4 or more ground stations with Mode A or Mode C transponders. Flight Radar are actively implementing this in Europe now. It requires a network called PlanePlotter to operate.&lt;/p&gt;&#xA;" OwnerUserId="172" LastActivityDate="2013-12-23T01:03:58.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="300" PostTypeId="2" ParentId="292" CreationDate="2013-12-23T01:44:50.280" Score="16" Body="&lt;p&gt;At least in the United States the FAA recently (I &lt;em&gt;think&lt;/em&gt; in 2012?) changed the recommendation for transponder operation in the AIM.  It now reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Civil and military transponders should be turned to the “on&quot; or normal altitude reporting position prior to moving on the airport surface to ensure the aircraft is visible to ATC surveillance systems. IN ALL CASES, WHILE IN CONTROLLED AIRSPACE EACH PILOT OPERATING AN AIRCRAFT EQUIPPED WITH AN OPERABLE ATC TRANSPONDER MAINTAINED IN ACCORDANCE WITH 14 CFR SECTION 91.413 MUST OPERATE THE TRANSPONDER, INCLUDING MODE C IF INSTALLED, ON THE APPROPRIATE CODE OR AS ASSIGNED BY ATC. IN CLASS G AIRSPACE, THE TRANSPONDER SHOULD BE OPERATING WHILE AIRBORNE UNLESS OTHERWISE REQUESTED BY ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Cribbed from &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot; rel=&quot;nofollow&quot;&gt;Chapter 4-1 of the AIM&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically &quot;Turn it on before you taxi, and turn it off right before you shut down the engine. Always use the Altitude mode (Mode C) unless ATC tells you otherwise.&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In practice having the transponder on while on the airport surface doesn't do much unless your field has something like &lt;a href=&quot;http://en.wikipedia.org/wiki/ASDE-X&quot; rel=&quot;nofollow&quot;&gt;ASDE-X&lt;/a&gt; which plots aircraft transponders on a screen in the tower, but it generally doesn't hurt anything and it ensures you don't forget to turn the transponder on when you take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operating your transponder while on the ground &lt;em&gt;may&lt;/em&gt; cause &quot;ground clutter&quot; on nearby radar station's displays (possibly setting off the conflict-alert system) - this is why many of us were taught to set our transponders to standby mode while on the ground. In practice this usually isn't an issue, and if it is a problem local ATC will ask you to &quot;&lt;em&gt;squawk standby while taxiing&lt;/em&gt;&quot; to resolve the issue.&lt;br&gt;&#xA;If anyone gives you a hard time about it copy the number and politely quote the AIM.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-09-21T19:21:47.140" LastActivityDate="2015-09-21T19:21:47.140" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="301" PostTypeId="2" ParentId="294" CreationDate="2013-12-23T02:23:10.173" Score="9" Body="&lt;p&gt;ATC and pilots must be able to communicate in English on international flights involving ICAO member states. There are 191 countries that are members of the ICAO, covering almost all of the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While communications may be performed in the local language, English must be used upon request on international flights. Controllers and flight crew engaged in communications for international flights should be proficient in spoken English in addition to English aviation phraseology. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some domestic airways and airports may require communications in the local language instead of English.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So English is sufficient if you stick to international airports and airways, but be sure to check the language requirements before you venture into foreign domestic airspace and airports.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-23T02:29:01.970" LastActivityDate="2013-12-23T02:29:01.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="303" PostTypeId="2" ParentId="134" CreationDate="2013-12-23T03:05:42.077" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://aerioncorp.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerion&lt;/a&gt; is planning a supersonic business jet which has a projected completion year of 2021:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NlAu8t.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an article &lt;a href=&quot;http://www.forbes.com/sites/grantmartin/2013/10/31/the-worlds-first-supersonic-business-jet-will-fly-in-2021/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Forbes&lt;/a&gt; have written about it.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="97" LastEditDate="2014-02-23T10:34:57.430" LastActivityDate="2014-02-23T10:34:57.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="304" PostTypeId="1" CreationDate="2013-12-23T03:35:57.453" Score="6" ViewCount="380" Body="&lt;p&gt;I plan on starting my flight training soon at the age of 41, but I don't want to stop at PPL and simply fly for fun: I want to ultimately be a CFI. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With this goal in mind, my question is what recommendations can my fellow aviation enthusiasts and experts give me in the planning I should do for my aviation education? Is there a specific type of facility to select for training, a progression of obtaining certificates and ratings I should follow, etc.?&lt;/p&gt;&#xA;" OwnerUserId="173" LastEditorUserId="65" LastEditDate="2015-01-20T15:51:25.377" LastActivityDate="2015-01-20T15:51:25.377" Title="How can I customize my training to become a flight instructor?" Tags="&lt;flight-training&gt;&lt;career&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="305" PostTypeId="1" AcceptedAnswerId="313" CreationDate="2013-12-23T04:56:30.433" Score="14" ViewCount="19475" Body="&lt;p&gt;I read that a three blade can improve climb performance and decrease noise.  How does that work?&lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="39" LastEditDate="2013-12-24T04:26:09.363" LastActivityDate="2013-12-24T04:26:09.363" Title="What's the difference between a two-blade prop and three-blade?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="306" PostTypeId="1" AcceptedAnswerId="360" CreationDate="2013-12-23T05:28:59.073" Score="12" ViewCount="2673" Body="&lt;p&gt;As the Pilot In Command of a private aircraft, what are the customs procedures that must be complied with before leaving, before returning, and upon arrival to the USA?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-24T03:23:11.637" LastActivityDate="2015-05-07T03:40:54.060" Title="What US customs procedures must the pilot of a private aircraft follow when traveling in and out of the country?" Tags="&lt;faa-regulations&gt;&lt;us-cbp&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="307" PostTypeId="1" AcceptedAnswerId="317" CreationDate="2013-12-23T06:01:10.703" Score="10" ViewCount="12697" Body="&lt;p&gt;In the US, what is the legal definition of aerobatic flight? What are the restrictions (both for the aircraft and its location/maneuvers) applied to aerobatic flight? I remember reading something about a restriction on degrees of pitch or bank, but I was looking around for it and can't seem to find it again.&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="69" LastEditDate="2014-01-18T18:04:06.620" LastActivityDate="2014-01-18T18:04:06.620" Title="What are the US definition and restrictions on aerobatic flight?" Tags="&lt;faa-regulations&gt;&lt;aerobatics&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="308" PostTypeId="1" AcceptedAnswerId="316" CreationDate="2013-12-23T06:14:21.990" Score="7" ViewCount="347" Body="&lt;p&gt;I was reading a forum for professional pilots and ran across a thread on lateral offset procedures during oceanic flight (apparently having the FMS offset the aircraft from the centerline of an oceanic track). How does lateral offset work? Is it required for all oceanic aircraft or optional for some operators? Is it explicitly assigned by ATC or is it an implicit part of oceanic flight? What is its purpose, and why isn't it used in non-oceanic airspace?&lt;/p&gt;&#xA;" OwnerUserId="79" LastActivityDate="2013-12-23T07:57:28.977" Title="How do oceanic lateral offset procedures work?" Tags="&lt;air-traffic-control&gt;&lt;fms&gt;&lt;oceanic&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="309" PostTypeId="1" AcceptedAnswerId="321" CreationDate="2013-12-23T06:22:23.093" Score="10" ViewCount="1817" Body="&lt;p&gt;According to FAA rules, controllers are required to hold aircraft 2 or 3 minutes for wake turbulence under certain conditions. When is that wake turbulence hold required, and when are pilots allowed to waive it? What is the correct way to request a waiver?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="69" LastEditDate="2014-01-06T13:47:30.217" LastActivityDate="2014-09-16T17:16:03.700" Title="When and how can pilots waive wake turbulence holds in the US?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;wake-turbulence&gt;&lt;holding&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="311" PostTypeId="1" CreationDate="2013-12-23T06:49:38.313" Score="29" ViewCount="8920" Body="&lt;p&gt;We've all heard the &quot;acts like a cushion of air&quot; explanation tossed casually around by CFIs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also plenty of books and reference materials that give a detailed, accurate, and complete explanation of ground effect, and which are incomprehensible to most student pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What's the simplest way to accurately explain ground effect?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="11671" LastEditDate="2015-10-27T23:15:37.623" LastActivityDate="2019-07-21T03:25:09.803" Title="What is ground effect?" Tags="&lt;aerodynamics&gt;&lt;ground-effect&gt;" AnswerCount="10" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="312" PostTypeId="1" CreationDate="2013-12-23T06:55:38.030" Score="26" ViewCount="20977" Body="&lt;p&gt;Whenever I hear anyone talking about P-Factor, (whether it be single-engine left turning tendencies or multi-engine loss of directional control scenarios), someone always brings up the fact that the descending blade of a propeller generates more thrust than the ascending blade.  I'm wondering why that's the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is P-Factor and why does it occur?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2020-01-02T03:00:26.570" Title="What's P-Factor and why does it occur?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="313" PostTypeId="2" ParentId="305" CreationDate="2013-12-23T06:56:09.773" Score="15" Body="&lt;p&gt;At the absolute simplest, compared to a two-bladed propeller, a slightly smaller three-bladed propeller can produce more thrust at a given RPM, improving climb performance. Because of the smaller diameter, the propeller tips actually travel slower than the equivalent two-bladed design, reducing noise inside and outside the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hartzell Propeller has a great &lt;a href=&quot;http://hartzellprop.com/faq/technical-questions/&quot;&gt;set of technical answers about propellers&lt;/a&gt;. Their explanation of why more blades produces less noise is pretty good:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A 2-blade propeller produces two pressure pulses per revolution, where a 3-blade propeller will produce three smaller pulses per revolution (for the same amount of total thrust) which is inherently smoother and therefore quieter. The 3-blade propeller will generally have a smaller diameter than the 2-blade propeller that it replaces, which also reduces the tip speed and noise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2013-12-24T03:47:11.187" LastActivityDate="2013-12-24T03:47:11.187" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="314" PostTypeId="2" ParentId="312" CreationDate="2013-12-23T07:09:55.973" Score="9" Body="&lt;p&gt;Rather than try to do a full ground school session, I'm going to point you at &lt;strong&gt;&lt;a href=&quot;http://www.av8n.com/how/htm/yaw.html#sec-p-factor&quot;&gt;the section on P-Factor in the awesome (free) textbook See How It Flies&lt;/a&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To attempt to paraphrase, it occurs when your aircraft is operating at high angles of attack. Just like the advancing blade on a helicopter produces more thrust because it's heading upwind, the descending blade of the propeller produces more thrust because it has a higher angle of attack relative to the aircraft's motion through the air.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-23T07:09:55.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="315" PostTypeId="1" AcceptedAnswerId="336" CreationDate="2013-12-23T07:14:13.650" Score="7" ViewCount="2982" Body="&lt;p&gt;There has been a lot discussion about replacing 121.5 MHz &lt;a href=&quot;http://en.wikipedia.org/wiki/Distress_radiobeacon&quot; rel=&quot;nofollow&quot;&gt;emergency locator transmitters (ELTs)&lt;/a&gt; with 406 MHz ELTs, since 121.5 MHz ELTs are no longer monitored by satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are private planes required to have 406 MHz ELTs for operation? Is there a deadline for conversion? Since this is a country-by-country regulation, I am interested in&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Canada&lt;/li&gt;&#xA;&lt;li&gt;U.S.&lt;/li&gt;&#xA;&lt;li&gt;Mexico&lt;/li&gt;&#xA;&lt;li&gt;Bahamas&lt;/li&gt;&#xA;&lt;li&gt;Europe&lt;/li&gt;&#xA;&lt;li&gt;Australia&lt;/li&gt;&#xA;&lt;li&gt;(other countries, if information is available.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="110" LastEditorUserId="65" LastEditDate="2015-03-03T15:23:35.510" LastActivityDate="2015-03-03T15:23:35.510" Title="Do 121.5 MHz ELTs have to be replaced with 406 MHz models?" Tags="&lt;emergency&gt;&lt;avionics&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="316" PostTypeId="2" ParentId="308" CreationDate="2013-12-23T07:46:00.793" Score="4" Body="&lt;p&gt;On high-altitude North Atlantic flights, planes can fly zero, one, or two miles to the right of the centerline of your assigned track. The offset is randomly selected. This is called Strategic Lateral Offset Procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's used in the oceanic flights or flights over remote land where there is typically no radar service, and ATC cannot &quot;see&quot; traffic separation. It provides, on average, additional horizontal separation between planes reducing the likelihood of midair collision and high altitude wake turbulence (which can occur as a result of RVSM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strategic lateral offsets can be authorized in en-route oceanic or remote continental airspace. The decision to apply a strategic lateral offset is the responsibility of the flight crew, and only where offsets have been authorized by the ATS and when the aircraft is equipped with automatic offset tracking capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/oceanic/documents/WATRS_Plus/DOC_4444_16.5_SLOP_25Feb2011.docx&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/oceanic/documents/WATRS_Plus/DOC_4444_16.5_SLOP_25Feb2011.docx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-23T07:57:28.977" LastActivityDate="2013-12-23T07:57:28.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="317" PostTypeId="2" ParentId="307" CreationDate="2013-12-23T08:12:58.880" Score="12" Body="&lt;p&gt;Aerobatic flight is &quot;an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGFAR.NSF/0/9c54cb14e91a41b8852566cf0067b9fe!OpenDocument&quot;&gt;FAA (91.303)&lt;/a&gt;, no person may operate an aircraft in aerobatic flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Over any congested area of a city, town, or settlement;&lt;/li&gt;&#xA;&lt;li&gt;Over an open air assembly of persons;&lt;/li&gt;&#xA;&lt;li&gt;Within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport;&lt;/li&gt;&#xA;&lt;li&gt;Within 4 nautical miles of the center line of any Federal airway;&lt;/li&gt;&#xA;&lt;li&gt;Below an altitude of 1,500 feet above the surface; or&lt;/li&gt;&#xA;&lt;li&gt;When flight visibility is less than 3 statute miles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aerobatic flight is sometimes considered to be flight with more than 30 degrees pitch or more than 60 degrees bank. This is incorrect. It applies to wearing a parachute. (FAR 91.307)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A normal category aircraft is certified for the following &quot;non-acrobatic&quot; operation: Stalls, lazy eights, chandelles, and steep turns, in which the angle of bank is not more than 60°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A utility category aircraft is certified for spins (if approved for plane), lazy eights, chandelles, and steep turns, or similar manoeuvres, in which the angle of bank is more than 60 degrees but not more than 90 degrees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An acrobatic category aircraft is required for other aerobatics.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2013-12-23T16:12:59.520" LastActivityDate="2013-12-23T16:12:59.520" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="318" PostTypeId="1" AcceptedAnswerId="329" CreationDate="2013-12-23T08:31:12.587" Score="11" ViewCount="42640" Body="&lt;p&gt;As we all know from our instrument training, the MOCA is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MINIMUM OBSTRUCTION CLEARANCE ALTITUDE (MOCA)- The lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments which &lt;strong&gt;meets obstacle clearance requirements&lt;/strong&gt; for the entire route segment and which &lt;strong&gt;assures acceptable navigational signal coverage only within 25 statute (22 nautical) miles&lt;/strong&gt; of a VOR. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whereas the MEA is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MINIMUM EN ROUTE IFR ALTITUDE (MEA)- The lowest published altitude between radio fixes which &lt;strong&gt;assures acceptable navigational signal coverage&lt;/strong&gt; and &lt;strong&gt;meets obstacle clearance requirements&lt;/strong&gt; between those fixes. The MEA prescribed for a Federal airway or segment thereof, area navigation low or high route, or other direct route applies to the entire width of the airway, segment, or route between the radio fixes defining the airway, segment, or route. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Both quotes taken straight from the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/M.HTM&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only difference in language is the bit about 22 miles from a VOR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, when you're within those 22 miles, there's no practical difference between a MEA and a MOCA, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aJe1W.png&quot; alt=&quot;MEA/MOCA difference on V84 within 22 NM of PMM&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If that's true, why is there an 1800 foot difference between the MEA and the MOCA within 22 miles of the PMM VOR on V84?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-04-05T00:45:02.600" Title="Is there a difference between MEA and MOCA within 22 nm of a VOR?" Tags="&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="319" PostTypeId="2" ParentId="306" CreationDate="2013-12-23T09:39:32.453" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ifim/airspace/&quot; rel=&quot;nofollow&quot;&gt;The FAA outlines the procedures on their website.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, you'll need proper documentation for the airplane, flight plans, passports for everyone on board, and more.&lt;/p&gt;&#xA;" OwnerUserId="50" LastActivityDate="2013-12-23T09:39:32.453" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="320" PostTypeId="1" AcceptedAnswerId="355" CreationDate="2013-12-23T14:27:25.267" Score="27" ViewCount="2643" Body="&lt;p&gt;This is a snippet from the &lt;a href=&quot;http://goo.gl/1jqQ56&quot; rel=&quot;noreferrer&quot;&gt;KESC RNAV 36&lt;/a&gt; approach.  It's a real procedure, I didn't photoshop it except to add highlighting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I was in the position that the blue aircraft is in (roughly 10 miles from WOKOL bearing approximately 320), and I had been cleared to WOKOL for the RNAV 36. I am assuming ATC did not explicitly tell me to do a procedure turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I supposed to do when I get to WOKOL?  The plate says NoPT, which is obviously a mistake.  Do I still fly the course reversal?  Do I whip into a 150 degree left turn over WOKOL as illustrated?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some relevant passages from the AIM:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AIM 5-4-9:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The procedure turn or hold-in-lieu-of-PT is a required maneuver when it is depicted on the approach chart, unless cleared by ATC for a straight-in approach. Additionally, the procedure turn or &lt;strong&gt;hold-in-lieu-of-PT is not permitted when the symbol “No PT” is depicted&lt;/strong&gt; on the initial segment being used, when a RADAR VECTOR to the final approach course is provided, or when conducting a timed approach from a holding fix.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;AIM 5-4-5 (D. 2. b.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The published procedure will be annotated to indicate when the course&#xA;  reversal is not necessary when flying within a particular TAA area;&#xA;  e.g., “NoPT.” Otherwise, the pilot is expected to execute the course&#xA;  reversal under the provisions of 14 CFR Section 91.175. The pilot&#xA;  &lt;strong&gt;may elect&lt;/strong&gt; to use the course reversal pattern when it is not required by the procedure, but must inform air traffic control and&#xA;  receive clearance to do so.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If an instrument plate contains errors, am I still required to comply with them?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8cew4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="69" LastEditDate="2013-12-27T01:42:13.727" LastActivityDate="2014-10-21T03:15:19.793" Title="If there is a misprint on an instrument plate, is a pilot required to comply with it?" Tags="&lt;faa-regulations&gt;&lt;approach&gt;&lt;iaps&gt;&lt;instrument-procedures&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="321" PostTypeId="2" ParentId="309" CreationDate="2013-12-23T15:47:27.460" Score="11" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0703.html&quot; rel=&quot;nofollow&quot;&gt;AIM 7-3-9&lt;/a&gt; lists the required separations. Behind a heavy aircraft, the departure hold is 3 minutes and it may not be waived. Behind a small aircraft, the hold may be waived on pilot request only:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3. Additionally, appropriate time or distance intervals are provided to departing aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Two minutes or the appropriate 4 or 5 mile radar separation when&#xA;  takeoff behind a heavy/B757 jet will be:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) From the same threshold.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) On a crossing runway and projected flight paths will cross.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) From the threshold of a parallel runway when staggered ahead of&#xA;  that of the adjacent runway by less than 500 feet and when the runways&#xA;  are separated by less than 2,500 feet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- Controllers may not reduce or waive these intervals.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. A 3-minute interval will be provided when a small aircraft will&#xA;  takeoff:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. From an intersection on the same runway (same or opposite direction) behind a departing large aircraft,&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. In the opposite direction on the same runway behind a large aircraft takeoff or low/missed approach.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- This 3-minute interval may be waived upon specific pilot&#xA;  request.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. A 3-minute interval will be provided for all aircraft taking off&#xA;  when the operations are as described in subparagraph b1 and 2 above,&#xA;  the preceding aircraft is a heavy/B757 jet, and the operations are on&#xA;  either the same runway or parallel runways separated by less than&#xA;  2,500 feet. Controllers may not reduce or waive this interval.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; The AIM &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html&quot; rel=&quot;nofollow&quot;&gt;4-3-10(f)&lt;/a&gt; (intersection takeoffs) also addresses this question, including suggested pilot phraseology for waiving the hold (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Controllers are required to separate small aircraft (12,500 pounds or&#xA;  less, maximum certificated takeoff weight) departing (same or opposite&#xA;  direction) from an intersection behind a large nonheavy aircraft on&#xA;  the same runway, by ensuring that at least a 3-minute interval exists&#xA;  between the time the preceding large aircraft has taken off and the&#xA;  succeeding small aircraft begins takeoff roll. To inform the pilot of&#xA;  the required 3-minute hold, the controller will state, “Hold for wake&#xA;  turbulence.” If after considering wake turbulence hazards, the pilot&#xA;  feels that a lesser time interval is appropriate, the pilot may&#xA;  request a waiver to the 3-minute interval. &lt;strong&gt;To initiate such a request,&#xA;  simply say “Request waiver to 3-minute interval,” or a similar&#xA;  statement.&lt;/strong&gt; Controllers may then issue a takeoff clearance if other&#xA;  traffic permits, since the pilot has accepted the responsibility for&#xA;  wake turbulence separation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wake turbulence in general is considered a key safety issue by the FAA and there is a large amount of information in the AIM, the ATC guide and elsewhere.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-09-16T17:16:03.700" LastActivityDate="2014-09-16T17:16:03.700" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="322" PostTypeId="2" ParentId="254" CreationDate="2013-12-23T15:56:45.820" Score="3" Body="&lt;p&gt;Yes, if you only carry one EFB, then you have to also carry paper charts as a backup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See AC 120-76B.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. Paper Data Removal. &lt;strong&gt;At least two operational EFBs are required&lt;/strong&gt; to remove paper&#xA;  products that contain aeronautical charts, checklists, or other data required by the operating rules. The design of the EFB function requires that no single failure or&#xA;  common mode error may cause the loss of required aeronautical information.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;If paper charts are &quot;required operating information&quot;&lt;/strike&gt; If you would otherwise be required to carry a paper chart, then you either still have to carry one, or else carry two EFBs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about part 91 operators?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft operated under part 91, except for parts 91F and 91K, require no EFB authorization or compliance with this AC, &lt;strong&gt;provided the EFB does not replace any equipment or operating information&lt;/strong&gt; required by the regulations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-01-10T21:54:15.970" LastActivityDate="2014-01-10T21:54:15.970" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="323" PostTypeId="1" AcceptedAnswerId="326" CreationDate="2013-12-23T16:07:08.057" Score="25" ViewCount="3583" Body="&lt;p&gt;I know there is controversy over the safety and utility of performing spins for training, but what are the regulations limiting them for training (solo and dual) or 'just for fun'?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="69" LastEditDate="2014-01-18T17:52:22.633" LastActivityDate="2017-10-30T03:26:15.983" Title="What are the restrictions on performing intentional spins?" Tags="&lt;faa-regulations&gt;&lt;spins&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="325" PostTypeId="2" ParentId="320" CreationDate="2013-12-23T16:17:03.910" Score="11" Body="&lt;p&gt;The literal answer to your question about complying with the plate is also in AIM 5-4-9, right after the piece you quoted (my bold):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE- The pilot may elect to use the procedure turn or&#xA;  hold-in-lieu-of-PT when it is not required by the procedure, but must&#xA;  first receive an amended clearance from ATC. &lt;strong&gt;If the pilot is uncertain&#xA;  whether the ATC clearance intends for a procedure turn to be conducted&#xA;  or to allow for a straight-in approach, the pilot must immediately&#xA;  request clarification from ATC&lt;/strong&gt; (14 CFR Section 91.123).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, any time you aren't sure or you suspect something is odd then you should just ask ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if your question is about this specific procedure and whether the NoPT notation is (or even can be) correct or not, you might want to phrase your question in that way.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-23T16:17:03.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="326" PostTypeId="2" ParentId="323" CreationDate="2013-12-23T16:34:11.273" Score="19" Body="&lt;p&gt;There are at least three FARs that apply (maybe more?). First, &quot;aerobatics&quot; as defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=0f7905af7a714fb61ba55c9ee7b12323&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.4.7.2&amp;amp;idno=14&quot; rel=&quot;noreferrer&quot;&gt;91.303&lt;/a&gt; seems to include spinning:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For the purposes of this section, aerobatic flight means an&#xA;  intentional maneuver involving an abrupt change in an aircraft's&#xA;  attitude, an abnormal attitude, or abnormal acceleration, not&#xA;  necessary for normal flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means the general restrictions in 91.303 would apply:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an aircraft in aerobatic flight—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Over any congested area of a city, town, or settlement;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Over an open air assembly of persons;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Within the lateral boundaries of the surface areas of Class B,&#xA;  Class C, Class D, or Class E airspace designated for an airport;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Within 4 nautical miles of the center line of any Federal airway;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Below an altitude of 1,500 feet above the surface; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) When flight visibility is less than 3 statute miles.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Second, spinning an aircraft not approved for spinning in the POH would be a violation of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=771eb1473b07812aed1de86536cd25df&amp;amp;n=14y2.0.1.3.10&amp;amp;r=PART&amp;amp;ty=HTML#14:2.0.1.3.10.1.4.5&quot; rel=&quot;noreferrer&quot;&gt;91.9&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.9   Civil aircraft flight manual, marking, and placard&#xA;  requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraph (d) of this section, no person may&#xA;  operate a civil aircraft without complying with the operating&#xA;  limitations specified in the approved Airplane or Rotorcraft Flight&#xA;  Manual, markings, and placards, or as otherwise prescribed by the&#xA;  certificating authority of the country of registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Finally, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.1.4.7&quot; rel=&quot;noreferrer&quot;&gt;91.13&lt;/a&gt; would also prohibit spinning a non-certificated aircraft because it's a 'catch-all' regulation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.13   Careless or reckless operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Aircraft operations for the purpose of air navigation. No person&#xA;  may operate an aircraft in a careless or reckless manner so as to&#xA;  endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But spinning itself is absolutely legal and is required for a flight instructor rating as described in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.8.1.2&quot; rel=&quot;noreferrer&quot;&gt;61.183.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: there's also a requirement in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.4.7.4&quot; rel=&quot;noreferrer&quot;&gt;91.307&lt;/a&gt; that if non-crewmembers are on board then parachutes are required for maneuvers with 'extreme' bank or pitch, unless the flight is a test or training flight:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Unless each occupant of the aircraft is wearing an approved&#xA;  parachute, no pilot of a civil aircraft carrying any person (other&#xA;  than a crewmember) may execute any intentional maneuver that exceeds—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;A bank of 60 degrees relative to the horizon; or&lt;/li&gt;&#xA;  &lt;li&gt;A nose-up or nose-down attitude of 30 degrees relative to the&#xA;  horizon.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(d) Paragraph (c) of this section does not apply to—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Flight tests for pilot certification or rating; or&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Spins and other flight maneuvers required by the regulations for&#xA;  any certificate or rating when given by—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) A certificated flight instructor; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) An airline transport pilot instructing in accordance with §61.67 of this chapter.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="72" LastEditDate="2014-02-01T07:17:30.230" LastActivityDate="2014-02-01T07:17:30.230" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="327" PostTypeId="2" ParentId="311" CreationDate="2013-12-23T18:27:10.050" Score="6" Body="&lt;p&gt;Simple explanation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When out of ground effect, air on the bottom of the wing has plenty of room to move around. When in ground effect, the air on the bottom of the wing can't move around nearly as well and therefore pushes the plane upward to try and make more room. &lt;/p&gt;&#xA;" OwnerUserId="178" LastActivityDate="2013-12-23T18:27:10.050" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="328" PostTypeId="1" AcceptedAnswerId="332" CreationDate="2013-12-23T18:49:12.290" Score="16" ViewCount="7975" Body="&lt;p&gt;Is it required when under VFR to contact an airfield's approach when approaching to land at a class D? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airnav.com/airport/KDLH&quot; rel=&quot;nofollow&quot;&gt;KDLH&lt;/a&gt; is my example airfield. They possess independent radar approach and departure (same frequency) with a separate tower frequency. What would be the process of approaching this airfield under VFR?&lt;/p&gt;&#xA;" OwnerUserId="178" LastEditorUserId="572" LastEditDate="2015-02-12T07:27:56.460" LastActivityDate="2020-12-15T20:21:51.417" Title="Is it required to contact approach when flying VFR into a Class D airfield?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;airspace&gt;&lt;visual-flight-rules&gt;&lt;class-d-airspace&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="329" PostTypeId="2" ParentId="318" CreationDate="2013-12-23T19:11:34.380" Score="3" Body="&lt;p&gt;You are right. Within 22 nautical miles of the VOR, there is no practical difference between an MEA and a MOCA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it should be noted that the 22 nmi is only a limitation if navigating via VOR's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;14 CFR - CHAPTER I § 91.177  Minimum altitudes for IFR operations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Operation of aircraft at minimum altitudes.&#xA;  Except when necessary for&#xA;  takeoff or landing, or unless otherwise&#xA;  authorized by the FAA, no person may&#xA;  operate an aircraft under IFR below—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The applicable minimum altitudes&#xA;  prescribed in parts 95 and 97 of this&#xA;  chapter. However, if both a MEA and a&#xA;  MOCA are prescribed for a particular&#xA;  route or route segment, a person may&#xA;  operate an aircraft below the MEA&#xA;  down to, but not below, the MOCA, provided&#xA;  the applicable navigation signals&#xA;  are available. &lt;strong&gt;For aircraft using VOR&#xA;  for navigation, this applies only when&#xA;  the aircraft is within 22 nautical miles&#xA;  of that VOR&lt;/strong&gt; (based on the reasonable&#xA;  estimate by the pilot operating the aircraft&#xA;  of that distance)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The MOCA provides &quot;obstacle clearance requirements for the entire route segment,&quot; so if the applicable navigation signal is GPS, and you're receiving it, then you've met the requirements. This is why sometimes you see a MOCA on segments which aren't within 22 nmi of any VOR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One other &lt;em&gt;practical&lt;/em&gt; difference to keep in mind is that, especially in mountainous areas, you're much more likely to get radar coverage, and have better communcations clarity, at the MEA than the MOCA (I saw this a lot in Idaho). In those cases, ATC is probably going to prefer the MEA.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2013-12-23T19:11:34.380" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="330" PostTypeId="1" AcceptedAnswerId="333" CreationDate="2013-12-23T19:18:28.583" Score="11" ViewCount="511" Body="&lt;p&gt;What liabilities apply to the owner of an aircraft who allows other pilots to use his aircraft for not-for-profit and non-commercial use? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: An aircraft owner has a friend that wants to use his aircraft on a semi-regular basis (20-40 hours/year). His friend is willing to pay a fair share of maintenance, hangar, fuel, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Liabilities not limited to insurance, but also regulation, maintenance, etc)&lt;/p&gt;&#xA;" OwnerUserId="178" LastEditorUserId="1696" LastEditDate="2015-10-07T14:57:34.367" LastActivityDate="2015-10-07T14:57:34.367" Title="When sharing an airplane, what liability does the owner bear?" Tags="&lt;usa&gt;&lt;aircraft-ownership&gt;&lt;insurance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="332" PostTypeId="2" ParentId="328" CreationDate="2013-12-23T19:43:11.427" Score="9" Body="&lt;p&gt;No it is not required to contact approach. Unless you have to go through a larger D, C or B airspace to get there. I don't know of any larger Ds in the US, but there are plenty of D-airfields underneath C and B airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Germany (and I think around Europe, not sure though), there's a distinction between the tower-D and the approach-D (the former being called D-CTR, and the other just D), to enter the approach-D you'd have to talk to approach, but if you can sneak under/around it, go ahead and call the tower directly, let them know where you are, and they'll tell you how to enter their airspace. In the US, they'll probably just tell you to enter the pattern (like &quot;N12345, enter and report the right base for runway 5&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Europe you need an explicit clearance and they'll usually tell you how to enter (like &quot;DEFGH, enter control zone via Echo, report Echo&quot;, Echo being a reporting point on the chart, Echo usually being to the east, with November, Whiskey and Sierra being north, west and south respectively (usually, that is, there may be more, and they may be placed differently, but they're always on the sectional or the terminal area chart)&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2013-12-23T19:43:11.427" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="333" PostTypeId="2" ParentId="330" CreationDate="2013-12-23T21:54:36.103" Score="8" Body="&lt;p&gt;Most of the liabilities (but not all) fall under the insurance of the aircraft. Your insurance policy is your largest liability. This is important not just for protection of your aircraft, but if your insurance ends up void in an incident, you could have a lawsuit on your hands. Don't assume that aviation insurance is similar to car insurance, either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Insurance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot (on plan)- Aviation insurance has 3 catagories: Pilot, Named Individuals, Other (explained later). The owner pays insurance based on their qualifications and those specifically named. If you are going to be borrowing on a regular basis, weigh the cost of adding you to the plan.&lt;/li&gt;&#xA;&lt;li&gt;Pilot (off plan) - Insurance specifies whether or not you may borrow the aircraft to others, but also what qualifications that pilot must have. You may have only have 100 hours and are insured, but the insurance company may ask for 500 hours of someone you borrow the aircraft to. &lt;/li&gt;&#xA;&lt;li&gt;Aircraft - Regardless of the pilot, if the aircraft is out of compliance on maintenance or airworthiness, it is not being flown legally and therefore voids the insurance. As the owner (primary on the insurance), this is your responsibility as an owner and the pilot's responsibility as PIC. Both of you can be hit for this one.&lt;/li&gt;&#xA;&lt;li&gt;Reimbursement - Just because it is non-commercial use, your insurance may still specify what you can be compensated for. This may be only the actual expenses of the flight (fuel, oil, airport fees) and may include limits on hourly charges for maintenance. Keep in mind that this does not authorize you to break regulation on commercial use. You cannot make a profit.&lt;/li&gt;&#xA;&lt;li&gt;Legal flight - Above all else, the flight must be legal. The flight needs to comply with all FAA regulations. &lt;/li&gt;&#xA;&lt;li&gt;Non-commercial use - I keep coming back to this, but this is very important. The pilot may be a commercial pilot, but this doesn't authorize them to use the aircraft for hire. With many insurance plans, you can have a CFI train you since you are the owner, but a CFI cannot train someone else and you cannot train someone else. This makes and aircraft for hire and requires a 100-hour inspection. &lt;/li&gt;&#xA;&lt;li&gt;Other - Pilots who do not own an aircraft may have their own (renters) policy. While this may cover liabilities of those in the aircraft, don't assume that this also covers your aircraft. A pilot paying $200/year won't likely have coverage for your shiny new Cirrus.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Other&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the owner, you have liability in accurate record keeping. If you fudge documents on your aircraft that make it appear FAA compliant to the PIC, then you can be held liable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Notes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are only the items that come to mind. Feel free to add. &lt;/p&gt;&#xA;" OwnerUserId="178" LastActivityDate="2013-12-23T21:54:36.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="334" PostTypeId="2" ParentId="311" CreationDate="2013-12-23T22:34:30.383" Score="9" Body="&lt;p&gt;The ground acts as an aerodynamic mirror. When the wing approaches the surface it is as if an inverted wing comes from below. Their high pressure areas amplify each other, increasing the efficiency and thereby reducing the drag.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2013-12-23T22:34:30.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="335" PostTypeId="2" ParentId="311" CreationDate="2013-12-23T22:42:18.090" Score="25" Body="&lt;p&gt;It's impossible to give a correct AND simple explanation I think. I would explain it like this if I was asked:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The downwash from the wings and the downward component of the wingtip vortices create a higher than normal pressure area below the wings because the air hits the ground and can't &quot;escape&quot;, increasing lift.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Induced drag is reduced because wingtip vortices (causing drag) can't fully develop close to the ground.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2013-12-24T00:46:04.590" LastActivityDate="2013-12-24T00:46:04.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="336" PostTypeId="2" ParentId="315" CreationDate="2013-12-23T23:11:47.820" Score="7" Body="&lt;p&gt;I can't speak for the other countries, but at the moment (December 2013), at least in the United States, the answer is &lt;strong&gt;no&lt;/strong&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA and the FCC have been engaged in a bit of a regulatory battle of wills on this subject, (most recently in March of 2013, and covered &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2010/July/20/FAA-says-no-to-FCC-ban-on-121-5-MHz-ELT.aspx&quot;&gt;by AOPA&lt;/a&gt;, &lt;a href=&quot;http://www.eaa.org/news/2013/2013-09-05_DOT-FAA-comment-on-FCC-ELT-proposal.asp&quot;&gt;EAA&lt;/a&gt;, and &lt;a href=&quot;http://www.avweb.com/avwebflash/news/Senators_ELT_Phaseout_208689-1.html&quot;&gt;AvWeb&lt;/a&gt; pretty extensively) - Basically the FCC wants us to take our 121.5MHz woop-woop boxes and make them &lt;em&gt;go away&lt;/em&gt;, because they're pretty lousy for search-and-rescue, and the FAA is, for the moment, telling the FCC to get stuffed because regulating aircraft is the FAA's job.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now just because you don't &lt;em&gt;have&lt;/em&gt; to replace your ELT doesn't mean you &lt;em&gt;shouldn't&lt;/em&gt; -- to be honest a 121.5MHz ELT is not much better than having no ELT at all (&lt;a href=&quot;https://www.cospas-sarsat.org&quot;&gt;COSPAS-SARSAT&lt;/a&gt; doesn't monitor 121.5 anymore), so you should consider the type of flying you do, and the likelihood of an incident where the ELT might be useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new 406MHz ELTs are vastly superior to 121.5MHz units for search-and-rescue performance, and if I were running a commercial operation, or flying regularly in an area were search-and-rescue help may be hard to come by if I had an emergency (like say Alaska) I'd fork over the cash for a GPS-enabled 406MHz ELT to replace the ancient 121.5MHz unit in my plane in a cold second. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-23T23:11:47.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="337" PostTypeId="2" ParentId="320" CreationDate="2013-12-24T00:17:39.947" Score="6" Body="&lt;p&gt;Other RNAV approaches have the NoPT labeled on the the side away from the runway. This one is probably a misprint. If you believe an approach is incorrect, you should ask ATC just to make sure. If you feel the need to differ from an approach as published, whether because of a misprint, weather, traffic, a whim, or an emergency, you should ask or inform ATC. &lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-24T00:17:39.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="338" PostTypeId="1" AcceptedAnswerId="354" CreationDate="2013-12-24T00:45:11.460" Score="7" ViewCount="295" Body="&lt;p&gt;Low Enroute IFR charts in Alaska (and maybe elsewhere?) have blue routes and MEAs for GPS equipped aircraft, such as T266, 7000G MEA, below. Is an IFR GPS sufficient to use these, or is WAAS required?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vjr8v.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="72" LastEditDate="2014-03-03T05:33:16.530" LastActivityDate="2014-03-03T05:33:16.530" Title="Do Special MEA altitudes and routes in Alaska require WAAS?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="339" PostTypeId="1" AcceptedAnswerId="340" CreationDate="2013-12-24T01:26:44.523" Score="10" ViewCount="1680" Body="&lt;p&gt;Piston aircraft engines require regular oil changes, and at least in the US it's something the FARs allow an owner with a private pilot certificate to do.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some of the things I should look for during an oil change (or what are some of the things I should be sure my shop is checking when they do an oil change)?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-24T01:43:33.953" Title="What should I look for / check during an oil change?" Tags="&lt;aircraft-maintenance&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="340" PostTypeId="2" ParentId="339" CreationDate="2013-12-24T01:26:44.523" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;First, a word of caution - Don't attempt your own oil changes on an aircraft unless you're familiar with the process, and have both the tools and skills you'll need to get it done right.&lt;br&gt;&#xA;  It's probably a good idea to have your mechanic supervise you on your first oil change, and check your work on the next few until you're sure you've got the hang of  it.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This isn't an oil-change how-to - just a list of stuff to look at to judge the general health of an engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Disclaimers and warnings out of the way, here's what I look for (or ask the shop to check) during an oil change:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Draining that dirty old oil&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;First, don't forget to grab a sample for oil analysis while you're draining (I'll talk about that a little later!).&lt;br&gt;&#xA;Now, while the oil is running out of the drain you're really looking for big chunks of metal coming out with it (or heaven forbid blocking the drain hole) You also want to make sure there is no nasty &lt;a href=&quot;http://www.youtube.com/watch?v=krFCWCzBIJo&quot;&gt;sludge&lt;/a&gt; coming out (that's a car in the video, but the principle is the much same).&lt;br&gt;&#xA;Basically what's coming out of the drain should look like oil. It'll be &lt;em&gt;dirty&lt;/em&gt; (dark to black, rather than the pretty clear-ish liquid you poured into the engine all those hours ago), but it should still be flowing nicely.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Obviously chunks of metal here would be bad. If you're noticing them in the drained oil you've got some serious mechanical damage in your engine and you need a mechanic to check it out.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Sludge generally means you need to talk to your mechanic too - often it means a bunch of low-time oil changes to clean out the gunk from the engine, but if it's severe it could indicate other engine problems that need attention&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Checking the Oil Screen&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;If your engine has an oil suction screen that can be removed and cleaned (as on most Lycoming engines), remove it and inspect it for any pieces of metal, then clean it and reinstall it.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As with chunks in the drained oil, bits of metal in the screen are often a sign of a serious mechanical problem - if you find any you're going to want to talk to your mechanic.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Inspecting the Oil Filter&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;As part of every oil change the filter should be cut open and inspected for fine metallic particles in the pleats. There are a few of ways to do this (one is to simply stretch the pleats out under a bright light and look at them, another is to wash the filter in a solvent and strain the used solvent through a coffee filter to see if any particles are left behind).&lt;br&gt;&#xA;&lt;a href=&quot;http://www.eaavideo.org/video.aspx?v=3735936001&quot;&gt;EAA has a great video on inspecting an oil filter - it's worth the 10 minutes to watch.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you find any bits of metal  in the filter you already know what I'm going to say -- you're going to want a mechanic to check things out. A very small amount of metal may not be a serious issue, or it might be the beginnings of an engine on a path to self-destruction. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Run an oil analysis&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Some people do an oil analysis every oil change, some people don't ever do one.&lt;br&gt;&#xA;Smarter people than me say it's probably a good idea to do them, so I consider it to be cheap insurance and a good window into where those &quot;bits of metal&quot; I keep talking about above might eventually start coming from.&lt;br&gt;&#xA;There are plenty of companies that do aviation oil analysis and for an idea on what's in the report &lt;a href=&quot;http://www.blackstone-labs.com/report-explanation.php&quot;&gt;check out Blackstone Labs' interactive report explanation page&lt;/a&gt;.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.eaavideo.org/video.aspx?v=1672104239&quot;&gt;There's another EAA video that talks about oil analysis which is worth the 3 minutes to watch too...&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note that a single oil analysis won't tell you much (unless things are REALLY out of whack) - it's the long term stability or trends that matter here, so if you're going to do an oil analysis be prepared to do them at every oil change from now on...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Do the things that aren't oil-related&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;An oil change is a good opportunity to do some other regular maintenance - Since the cowling is off anyway why not clean/gap/rotate your spark plugs (which is another mind-numbing task the FARs allow owners with a private pilot certificate to do)?&lt;br&gt;&#xA;In fact since the cowling is apart and your engine is naked now's the time to give it a good once over for any loose parts, chafing wires, etc. that might have come up since the last oil change or service that had someone under the cowling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's probably also a good opportunity to check all your lights (interior and exterior), and break out the manufacturer's lubrication chart to see if there are any other things that need to be oiled, greased, cleaned, or sprayed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;So what's all this fuss about metal?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;You've probably noticed above that I'm really harping on all the ways you can find metal in your oil in this answer.  The simple fact is that all engines wear, and eventually they &lt;em&gt;wear out&lt;/em&gt;. That wear shows up as microscopic bits of metal relatively harmlessly suspended in the oil (what the oil analysis picks up), but if that wear suddenly accelerates bigger pieces of metal start getting torn off of the moving parts in your engine, and showing up in other places like the oil filter and screen, letting you know something is wrong with your engine, and &lt;em&gt;hopefully&lt;/em&gt; letting you know on the ground rather than in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't want to give the wrong impression here though: Not every bit of metal that turns up in an oil filter will be a death sentence for the engine that produced it! In fact brand new engines sometimes produce a few bits of metal during break-in as parts wear in to each other, and they stop after the first oil change or two. The thing to remember is any metal showing up where it shouldn't be during an oil change is definitely something to have checked out by a mechanic.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-24T01:43:33.953" LastActivityDate="2013-12-24T01:43:33.953" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="341" PostTypeId="1" CreationDate="2013-12-24T02:06:10.020" Score="17" ViewCount="1405" Body="&lt;p&gt;A friend of mine has had Type 1 diabetes most of his life, and has it well under control.  How does he go about finding out if he can get his medical and learn to fly?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="65" LastEditDate="2015-03-03T15:25:51.760" LastActivityDate="2020-06-24T12:30:17.843" Title="Can a person with Type 1 Diabetes get a medical and learn to fly?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;&lt;faa-approval&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="342" PostTypeId="1" AcceptedAnswerId="344" CreationDate="2013-12-24T02:25:54.690" Score="18" ViewCount="2536" Body="&lt;p&gt;I was flying on &lt;a href=&quot;http://www.flyporter.com&quot; rel=&quot;noreferrer&quot;&gt;Porter Airlines&lt;/a&gt; and they had an info card about how similar the Bombardier (I still say DeHavilland) Dash 8 Q400s are to the &lt;a href=&quot;http://cseries.com&quot; rel=&quot;noreferrer&quot;&gt;Bombardier CSeries&lt;/a&gt; they have ordered.&lt;/p&gt;&#xA;&lt;p&gt;There was a cool overlay photo to show relative sizes and shapes:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZkBrg.png&quot; alt=&quot;Dash 8 vs CSeries&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Looking at that image, it got me wondering about the straight vs angled wing.  Straight vs angled tails, etc.&lt;/p&gt;&#xA;&lt;p&gt;I get that a jet is faster than a turbo prop.&lt;/p&gt;&#xA;&lt;p&gt;Cseries cruise speeds are:&#xA;Mach 0.78 (828 km/h, 447 kn, 514 mph)&lt;/p&gt;&#xA;&lt;p&gt;Dash8 Q400 cruise speeds are:&#xA;414 mph (667 km/h) 360 knots&lt;/p&gt;&#xA;&lt;p&gt;Those are pretty close and yet that is a pretty radical wing design change.&lt;/p&gt;&#xA;&lt;p&gt;Is this just the history an old design (Dash 8) vs a very modern design?&lt;/p&gt;&#xA;" OwnerUserId="80" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-06-06T19:38:46.253" Title="Why the different wing and tail designs in similar sized jets vs turbo prop?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;&lt;dash-8&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="343" PostTypeId="2" ParentId="341" CreationDate="2013-12-24T02:41:36.133" Score="11" Body="&lt;p&gt;As far as the FAA is concerned your friend &lt;em&gt;can&lt;/em&gt; get a medical, but he will need a &lt;em&gt;special issuance&lt;/em&gt; medical, will only qualify for a third-class medical, and will be prohibited from operating aircraft outside the United States.&lt;br&gt;&#xA;In addition there are some specific &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/dec_cons/disease_prot/diabetes_insulin/initial/&quot; rel=&quot;noreferrer&quot;&gt;requirements to obtain the special-issuance medical for insulin-dependent diabetics&lt;/a&gt;, and monitoring requirements before and during flight which must be adhered to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/dec_cons/disease_prot/diabetes_insulin/&quot; rel=&quot;noreferrer&quot;&gt;FAA has a page of guidance for Aviation Medical Examiners&lt;/a&gt; that deals with insulin-dependent diabetes which your friend should review (and be prepared to discuss with their AME).&lt;br&gt;&#xA;&lt;a href=&quot;http://www.diabetes.org/living-with-diabetes/know-your-rights/discrimination/employment-discrimination/pilots-and-diabetes-discrimination/faa-medical-certification.html&quot; rel=&quot;noreferrer&quot;&gt;Diabetes.org also has a page on Diabetes and FAA Certification&lt;/a&gt;, and &lt;a href=&quot;http://aopa.org&quot; rel=&quot;noreferrer&quot;&gt;AOPA&lt;/a&gt;'s medical folks would be a useful resource to help ensure that the special issuance medical goes through without any hiccups.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-03-03T15:26:30.093" LastActivityDate="2015-03-03T15:26:30.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="344" PostTypeId="2" ParentId="342" CreationDate="2013-12-24T03:52:15.557" Score="13" Body="&lt;p&gt;Well, for starters, the speeds are actually pretty significantly different. The Cseries is almost 25% faster than the Q400. Swept airfoils are much more efficient at those higher speeds, as are jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Q400 is also a wildly stretched version of the original DeHavilland Canada DHC-8 (Dash 8), which was itself based on the 4-engine DHC-7 (Dash 7) STOL airliner. DHC has a lot of history building short takeoff and landing aircraft with pretty extreme performance, and a lot of that colored the design of the Dash 8. What you see today in the Q400 is the result of about 70 years of backcountry aircraft design, applied to a commuter airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cseries, on the other hand, is a clean-sheet Bombardier design meant to compete with the E-jets and the smallest 737s (and 717).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully that answers your questions!&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2013-12-24T03:52:15.557" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="345" PostTypeId="1" AcceptedAnswerId="361" CreationDate="2013-12-24T04:25:27.923" Score="12" ViewCount="1828" Body="&lt;p&gt;If conditions at a towered airport are not IFR, can pilots request a special VFR clearance? For example, at a Class D airport, &lt;strong&gt;ceiling 1300 broken, 10 sm visibility&lt;/strong&gt; is technically too low to remain in the pattern (assuming a 1000 foot AGL pattern and maintaining at least 500 feet below clouds), yet it is not IFR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a Special VFR clearance, the pilot would be able to maintain a 1000 foot pattern and remain clear of clouds. If the pilot requests SVFR, will the tower grant it?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2014-01-18T17:53:55.483" LastActivityDate="2015-01-19T16:27:37.943" Title="To receive an SVFR clearance, does the airport need to be reporting IFR conditions?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;special-vfr&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="346" PostTypeId="2" ParentId="239" CreationDate="2013-12-24T05:22:09.323" Score="6" Body="&lt;p&gt;I'm not sure how common flap load relief systems are - I know the Airbus A330 has them and I believe all the Airbus A3xx series do. I've also found &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/340657/&quot; rel=&quot;nofollow&quot;&gt;at least one post that seems to imply it's common on most &quot;large commercial&quot; aircraft&lt;/a&gt;, which I assume encompasses most transport category aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Airbus the system is based on airspeed - When the maximum flap extension speed (V&lt;sub&gt;FE&lt;/sub&gt;) is exceeded by a certain threshold the ship's computer automatically retracts the flaps.&lt;br&gt;&#xA;My understanding is the retraction is staged, so if you've got full flaps selected and exceed V&lt;sub&gt;FE&lt;/sub&gt; for that flap setting the system takes out one notch -- presumably it would continue doing so if you're still exceeding the operating limitations of the flap system until it reaches a point where it's convinced you're not going to damage the airframe.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the overspeed condition is corrected (the speed has reduced to below V&lt;sub&gt;fe&lt;/sub&gt; by a set threshold) the flaps are returned to the selected position.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-03-03T15:29:34.100" LastActivityDate="2015-03-03T15:29:34.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="347" PostTypeId="1" AcceptedAnswerId="387" CreationDate="2013-12-24T06:00:13.170" Score="21" ViewCount="6833" Body="&lt;p&gt;As temperatures here in New York plunge toward (and below) freezing it's time for those of us without nice heated hangars to start thinking about pre-heating our aircraft before we turn the key.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201505%20%2807-01-2002%29/Cold%20Weather%20Starting.pdf&quot;&gt;Lycoming SI 1505&lt;/a&gt; tells me that &quot;&lt;em&gt;The use of pre-heat will facilitate starting during cold weather, and is required when the engine has been allowed to drop to temperatures below +10°F/-12°C (+20°F/-6°C for –76 series engine models)&lt;/em&gt;&quot;, but the general recommendations I've been given are to preheat if it's been below freezing in the last 4 hours.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what temperature does it start to become beneficial to preheat a piston aircraft engine prior to starting, and how does one ensure that the engine is thoroughly and evenly heated?&lt;br&gt;&#xA;I'm pre-heating on the ramp, using a forced-hot-air heater.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="97" LastEditDate="2014-01-13T01:58:04.460" LastActivityDate="2015-05-18T05:14:45.143" Title="When is pre-heating a piston engine important, and how does one pre-heat correctly?" Tags="&lt;weather&gt;&lt;piston-engine&gt;&lt;cold-weather&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="348" PostTypeId="1" AcceptedAnswerId="604" CreationDate="2013-12-24T15:22:14.127" Score="11" ViewCount="1329" Body="&lt;p&gt;When designing an airplane meant to cruise at transonic speeds (or supersonic speeds), I heard that one should look at the isobars on the main wing in order to assess if the shape, sweep angle and other airfoil parameters are suitably chosen. I also read that the better configuration yields isobars that are parallel to the leading edge. I already know that there are several techniques to get the isobars aligned with the leading edge (area ruling, adapting the sweep angle, extra care in the design of the junction between the fuselage and the wing), but why is this configuration better than another one? What does it improve?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="14897" LastEditDate="2019-03-22T08:22:56.497" LastActivityDate="2019-03-22T08:22:56.497" Title="Why should isobars be aligned with the leading edge of the main wing for a transonic cruiser?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;wing-sweep&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="349" PostTypeId="2" ParentId="345" CreationDate="2013-12-24T17:08:56.987" Score="4" Body="&lt;p&gt;&lt;strong&gt;In Europe&lt;/strong&gt;, a SVFR clearance may be given when meteorological conditions are below VFR &lt;strong&gt;&lt;em&gt;within the control zone of the airport&lt;/em&gt;&lt;/strong&gt; (ceiling below 1,500ft AGL and visibility less than 5km). The clearance can only be given when the aircraft can stay clear of clouds, see the ground and with a minimum surface visibility of 1.5km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, if the visibility is between 1.5km and 5km and/or the ceiling is between 1,000ft and 1,500fr AGL, a SVFR clearance can be requested. Those conditions are not solid IFR though. Also, SVFR can never be offered to the pilot. The pilot has to explicitly ask for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The rules for SVFR are different in the U.S.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2013-12-24T17:08:56.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="350" PostTypeId="1" AcceptedAnswerId="353" CreationDate="2013-12-24T17:42:44.427" Score="5" ViewCount="1229" Body="&lt;p&gt;What's the procedure to use the Bendix/King KAP 140 autopilot in the Cessna piston singles to climb to a certain altitude and then capture it and level off?&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="100" LastEditDate="2020-05-04T08:54:41.987" LastActivityDate="2020-05-04T08:54:41.987" Title="What is the procedure to climb and level off using a Bendix/King KAP140 autopilot?" Tags="&lt;autopilot&gt;&lt;altitude&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="351" PostTypeId="1" AcceptedAnswerId="571" CreationDate="2013-12-24T17:53:23.633" Score="24" ViewCount="6322" Body="&lt;p&gt;I noticed on &lt;a href=&quot;http://skyvector.com&quot;&gt;SkyVector&lt;/a&gt; that, for example, the Resolute Bay VOR (&lt;a href=&quot;http://skyvector.com/?ll=74.73084486128703,-94.93217468569226&amp;amp;chart=301&amp;amp;zoom=2&quot;&gt;YRB&lt;/a&gt;) and Baker Lake VOR (&lt;a href=&quot;http://skyvector.com/?ll=64.32142699248374,-96.10464477842463&amp;amp;chart=301&amp;amp;zoom=1&quot;&gt;YBK&lt;/a&gt;) seem to be oriented in such a way that the 360 radial is pointing in the direction of true north (and I don't think the variation is anywhere near zero there).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know VORs are supposed to be oriented according to magnetic north, but is it common practice close to the magnetic poles to have them point true instead? If so, is there any way to tell if a particular VOR is doing just that, except looking at the chart and noticing that the small arrow is pointing north rather than off to one side?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="19" LastEditDate="2015-02-23T13:07:42.237" LastActivityDate="2018-10-07T04:41:30.373" Title="How are VORs oriented near the magnetic poles?" Tags="&lt;navigation&gt;&lt;vor&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="352" PostTypeId="2" ParentId="351" CreationDate="2013-12-24T18:07:30.247" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;noreferrer&quot;&gt;VOR stations&lt;/a&gt; in areas of magnetic compass unreliability are oriented with respect to True North.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think you can tell if it's pointing true north by looking at the charts. However, it doesn't really matter anyway because your own compass would be unreliable as well when flying in the vicinity of such a VOR. After all, when navigating using a VOR, you don't fly a heading, you fly a radial.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="65" LastEditDate="2015-02-23T15:37:07.960" LastActivityDate="2015-02-23T15:37:07.960" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="353" PostTypeId="2" ParentId="350" CreationDate="2013-12-24T19:08:56.667" Score="3" Body="&lt;p&gt;Only the KAP140 two-axis autopilot with altitude preselect supports capturing a preselected altitude (which is the one installed in the Cessna 172 before the introduction of the Garmin GFC700)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Preselect the desired altitude using the altitude preselect knob, switch to VS mode, select the desired VS and the AP will switch to altitude hold mode when the preselected altitude is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taken from &lt;a href=&quot;http://www.bendixking.com/HWL/media/PDF/PilotsGuides/PG-KAP140.pdf&quot; rel=&quot;nofollow&quot;&gt;the manual&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="97" LastEditDate="2015-05-03T04:06:23.007" LastActivityDate="2015-05-03T04:06:23.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="354" PostTypeId="2" ParentId="338" CreationDate="2013-12-24T19:44:51.550" Score="5" Body="&lt;p&gt;The answer appears to be yes. The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/notices/2013-11-14/AH03004.HTM&quot;&gt;FAA document&lt;/a&gt; that describes this rule says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TSO C145a and TSO C146a GPS WAAS navigation systems are authorized to&#xA;  be used as the only means of navigation on Federal airways and other&#xA;  published ATS routes in lieu of ground-based navigation aids in Alaska&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.pra.org/publicdl/Ground%20School%20Training/NACO%20Aeronautical%20Chart%20Users%20Guides/8th_ifr_intro.pdf&quot;&gt;IFR chart legend&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To utilize these routes aircraft will need to be equipped with IFR&#xA;  approved Global Navigation Satellite System (GNSS). In Alaska,&#xA;  TSO-145a and 146a equipment is required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And both TSO &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgtso.nsf/0/8f5172f7537bbc6286256dad00643ce3!OpenDocument&quot;&gt;C145&lt;/a&gt; and &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgtso.nsf/0/BD9399D32EE5750A86256DAD00643D48?OpenDocument&quot;&gt;C146&lt;/a&gt; specifically mention WAAS in their titles.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-24T19:44:51.550" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="355" PostTypeId="2" ParentId="320" CreationDate="2013-12-24T20:47:03.433" Score="39" Body="&lt;p&gt;The first thing that you should do is check the NOTAM's for the airport (which of course, you should do before you leave on your flight).  Very often, these types of errors have been discovered by someone else and the FAA will have issued a NOTAM to let everyone know.  In this case there is no NOTAM, so we would have had no reason to suspect an issue before we took off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main point has already been made.  If you are airborne and there is any reason to suspect that something is wrong, ask ATC for clarification and move on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I encountered this situation and couldn't ask for clarification (ie. lost communication) then I would simply select a different approach and fly it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the record, the Jeppesen chart has it coded correctly:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GTK0z.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, aside from the operational considerations, it is very important to notify the FAA when you find discrepancies like this so that they can be fixed.  Here is a quote from the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;REPORTING CHART DISCREPANCIES&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Your experience as a pilot is valuable&#xA;  and your feedback is  important. We make every effort to display&#xA;  accurate information  on all FAA charts and publications, so we&#xA;  appreciate your input.  Please notify us concerning any requests for&#xA;  changes, or potential  discrepancies you see while using our charts&#xA;  and related products.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;FAA, AeroNav Products&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;SSMC4 Sta. 4503&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;1305 East-West Highway&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;Silver Spring, MD 20910-3281&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Telephone Toll-Free 1-800-626-3677&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;E-mail: 9-AMC-Aerochart@faa.gov&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Mark the chart you are using with the suggested&#xA;  changes and  include an explanation of the discrepancy. Mail this&#xA;  corrected  chart to the address above and we will send you a&#xA;  replacement  right away. Suggestions concerning this guide are also&#xA;  welcome.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For the record, I have already emailed the plate with the suggested changes to the email address above (on 24 DEC 2013), and hopefully a NOTAM will be issued soon and an amended approach procedure will follow sometime after.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Update (09 JAN 2014)&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I received the following response from the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dear Louis: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Thank you for reporting the problem&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Control Number 18335 has been assigned to this issue for tracking&#xA;  purposes.  This concern has been closed with the following Response:   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Thank You for your inquiry. A P-NOTAM is being assigned to correct the discrepancy.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Regards,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the NOTAM hasn't been issued as of yet.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Update 2 (17 JAN 2014)&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;New NOTAM issued to address the error on the instrument approach procedure:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;!FDC 4/3036 ESC IAP DELTA COUNTY, ESCANABA, MI.&#xA;   RNAV (GPS) RWY 36, ORIG...&#xA;     CHANGE TAA TO READ FROM 274/30 CW 094/30 (NOPT) TO WOKOL&#xA;     (IF/IAF) AND FROM 094/30 CW 274/30 TO WOKOL (IF/IAF).&#xA;   THIS IS RNAV (GPS) RWY 36, ORIG-A.&#xA;   1401171859-PERM&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;h1&gt;Update 3 (06 MAR 2014):&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;New, corrected chart issued and the NOTAM was cancelled the next day.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-10-21T03:15:19.793" LastActivityDate="2014-10-21T03:15:19.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="356" PostTypeId="2" ParentId="347" CreationDate="2013-12-24T20:59:57.920" Score="5" Body="&lt;p&gt;Mike Busch, in &lt;a href=&quot;http://www.eaavideo.org/video.aspx?v=1149666747001&quot; rel=&quot;nofollow&quot;&gt;an EAA webinar&lt;/a&gt; dated 8 September 2011 claims fantastic Engine longevity. He calls a start with the engine below 20°F a significant wear event, recommending preheat below 32°F.  Pumping forced air through the cowling for 15 minutes, time enough for a thorough preflight, records check etc, should do the trick.  Be careful not to blister the finish on your cowling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning the &quot;Why&quot;, I suppose the main reason is that aluminum and steel composing the engine have dissimialr Coefficents of thermal expansion (Cte), and cold temperatures, far outside their operating range, can move the fit of parts out of tolerance.  Regarding &quot;How&quot; to make sure your engine is sufficiently pre-headted, I suppose you could watch the oil temperature guage.  Mine starts at 50F. I would be comfortable starting the engine if the needle had at least made it off the peg, but this may take a long time.  Since Oil plays such an important role in temperature control of the engine, some preheaters attach magnetically to the oil pan. I have heard of some pilots sending heated air up the exhaust stacks in an effort to heat the internals.  I don't know how effective that is in heating the oil.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="97" LastEditDate="2015-05-03T04:06:45.897" LastActivityDate="2015-05-03T04:06:45.897" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="357" PostTypeId="1" CreationDate="2013-12-24T21:25:57.690" Score="11" ViewCount="1645" Body="&lt;p&gt;Obviously, obstacle clearance, charts, atc instructions etc. can require a specific rate of climb or descent, or at least pose limits that are easily calculated. When no such restrictions apply, there appears to be a large amount of freedom in selecting a vertical speed for reaching a certain instructed altitude. Are there standard rates in common use? What (preferably quantifiable) factors help pilots decide how quickly they want to get to their desired altitude? &lt;/p&gt;&#xA;" OwnerUserId="67" LastEditorUserId="1696" LastEditDate="2018-04-16T18:15:43.130" LastActivityDate="2018-04-16T18:15:43.130" Title="How to decide on a rate of climb or descent if no specific vertical speed is required?" Tags="&lt;aircraft-operations&gt;&lt;vertical-speed&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="358" PostTypeId="2" ParentId="328" CreationDate="2013-12-24T21:32:38.783" Score="4" Body="&lt;p&gt;Out of courtesy, you MAY contact approach when VFR, but it is by no means necessary. Judging by the 86th issue of the Green Bay sectional, it is not even obvious that radar services are available.  The procedure would be to listen to ATIS on 124.1 and contact tower before entering the class D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe this is true even if you are flying into a class D airfield with charted TRSA, such as Fargo (FAR) or Tri-Cities (TRI)  You are welcome and encouraged to lookup the frequency on the edge of the chart, (it will likely be contained in the ATIS) contact approach during the approach to the field, but it is by no means compulsory.  You can make your desire for non-participation clear by stating &quot;Negative Radar Service&quot; in your initial contact, arriving or departing.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="182" LastEditDate="2014-01-22T16:30:48.643" LastActivityDate="2014-01-22T16:30:48.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="359" PostTypeId="2" ParentId="357" CreationDate="2013-12-24T21:48:48.250" Score="11" Body="&lt;p&gt;In general terms, the higher you are the better your fuel efficiency, so you will want to climb quickly and then stay as high as you can until you need to start your descent in order to land.  For jets, a common way to approximate your top of descent is by using the &quot;3:1 rule&quot; where you take your desired altitude loss in thousands of feet and multiply it by three.  For instance if you need to lose 35,000 ft. you would start down 105NM ($\frac{35000ft \times 3NM}{1000ft}$) prior to your destination, staying at altitude until then in order to save fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as your rate, the first place I would check would be the AFM of the airplane that you are flying.  Smaller airplanes will have Vy (best rate of climb speed) that may be used for this purpose unless another speed is specified (to help with cooling, etc).  Larger aircraft often have specific climb and descent schedules (for example, climb at 250 KIAS until 10,000 ft then 300 KIAS until you transition to Mach 0.76) which the manufacturer recommends and provides performance information for.  Fly these speeds and take what vertical speed that you get.  Usually, &lt;em&gt;flying by the book&lt;/em&gt; is the place to start unless you have a specific reason to do otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0404.html&quot; rel=&quot;nofollow&quot;&gt;AIM 4-4-10&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;d. When ATC has not used the term “AT PILOT'S DISCRETION” nor imposed any climb or descent restrictions, pilots should initiate climb or descent promptly on acknowledgement of the clearance. Descend or climb at an optimum rate consistent with the operating characteristics of the aircraft to 1,000 feet above or below the assigned altitude, and then attempt to descend or climb at a rate of between 500 and 1,500 fpm until the assigned altitude is reached. If at anytime the pilot is unable to climb or descend at a rate of at least 500 feet a minute, advise ATC. If it is necessary to level off at an intermediate altitude during climb or descent, advise ATC, except when leveling off at 10,000 feet MSL on descent, or 2,500 feet above airport elevation (prior to entering a Class C or Class D surface area), when required for speed reduction.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt; &lt;em&gt;Leveling off at 10,000 feet MSL on descent or 2,500 feet above airport elevation (prior to entering a Class C or Class D surface area) to comply with 14 CFR Section 91.117 airspeed restrictions is commonplace. Controllers anticipate this action and plan accordingly. Leveling off at any other time on climb or descent may seriously affect air traffic handling by ATC. Consequently, it is imperative that pilots make every effort to fulfill the above expected actions to aid ATC in safely handling and expediting traffic.&lt;/em&gt;  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="72" LastEditDate="2014-04-23T12:29:51.607" LastActivityDate="2014-04-23T12:29:51.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="360" PostTypeId="2" ParentId="306" CreationDate="2013-12-24T22:57:18.757" Score="8" Body="&lt;p&gt;&lt;strong&gt;General&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Each person leaving the country must be authorized to return to the US.  (ie. they are a US citizen or their visa allows them to leave and return to the US.)&lt;/li&gt;&#xA;&lt;li&gt;Ensure that you have all required paperwork&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot license&lt;/li&gt;&#xA;&lt;li&gt;Medical&lt;/li&gt;&#xA;&lt;li&gt;Aircraft Registration&lt;/li&gt;&#xA;&lt;li&gt;The aircraft must have a current &lt;a href=&quot;https://dtops.cbp.dhs.gov/&quot; rel=&quot;nofollow&quot;&gt;customs decal&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Ensure that the aircraft is properly equipped&#xA;&lt;ul&gt;&#xA;&lt;li&gt;12&quot; Registration Numbers&lt;/li&gt;&#xA;&lt;li&gt;Transponder&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Before Leaving the US&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;File eAPIS&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://eapis.cbp.dhs.gov/&quot; rel=&quot;nofollow&quot;&gt;eAPIS&lt;/a&gt; is required to be filed at least 60 minutes prior to your departure.&lt;/li&gt;&#xA;&lt;li&gt;Other third party services (ie. &lt;a href=&quot;http://www.flightplan.com&quot; rel=&quot;nofollow&quot;&gt;FlightPlan.com&lt;/a&gt;, etc.) may make this easier if you do it a lot.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;File an international flight plan&#xA;&lt;ul&gt;&#xA;&lt;li&gt;May be an instrument or a defence VFR flight plan&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Before Returning to the US&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;File eAPIS (see above)&lt;/li&gt;&#xA;&lt;li&gt;File a flight plan (see above)&lt;/li&gt;&#xA;&lt;li&gt;Notify customs and obtain permission at least one hour prior to landing in the US.  Record the initials of the customs officer that you spoke to just in case they misplace your notification.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Note that if you are coming from locations &quot;south of the US&quot; (for the specific definition, see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d10359b0d7b5c0bda361264cb132db96&amp;amp;mc=true&amp;amp;node=se19.1.122_123&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;), you must stop at the &lt;em&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d10359b0d7b5c0bda361264cb132db96&amp;amp;mc=true&amp;amp;node=se19.1.122_124&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;designated airport&lt;/a&gt;&lt;/em&gt; closest to your point of border crossing to clear customs (unless you have an overflight permit).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Upon Arrival in the US&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You must land at an &lt;a href=&quot;http://www.cbp.gov/sites/default/files/documents/Airports%20where%20CBP%20Inspection%20Services%20are%20Normally%20Available%20%28Jan2015%29.pdf&quot; rel=&quot;nofollow&quot;&gt;airport of entry&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Report immediately to the designated customs location&lt;/li&gt;&#xA;&lt;li&gt;Do not allow anybody or anything to leave/enter the aircraft until the customs official gives your permission&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The only exception that I know of to this are the South Florida airports where you are expected to take all people and belongings into the customs facility for inspection.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Discard any international garbage in the approved manner.&lt;/li&gt;&#xA;&lt;li&gt;Provide required paperwork&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;http://www.cbp.gov/travel/clearing-cbp/traveler-entry-form&quot; rel=&quot;nofollow&quot;&gt;Customs Declaration&lt;/a&gt; for each arriving family&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Wait for customs to specifically tell you that you are cleared before you attempt to leave.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Notes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not all-encompassing, please help add to and expand this list so that others may learn from our experience!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A TON of useful information is made available by the FAA in the &lt;a href=&quot;http://xpda.com/flyingtoeurope/private_%20flyers_1.pdf&quot; rel=&quot;nofollow&quot;&gt;Guide for Private Flyers&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-05-07T03:40:54.060" LastActivityDate="2015-05-07T03:40:54.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="361" PostTypeId="2" ParentId="345" CreationDate="2013-12-24T23:13:30.953" Score="10" Body="&lt;p&gt;A Special VFR (SVFR) clearance may be issued to a pilot when:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The weather is below VFR weather minimums, as reported at the intended airport&lt;/li&gt;&#xA;&lt;li&gt;The pilot is able to remain clear of clouds&lt;/li&gt;&#xA;&lt;li&gt;The pilot has at least one mile flight visibility (other than helicopters) at all times&lt;/li&gt;&#xA;&lt;li&gt;The pilot is operating (or wants to operate) within the lateral boundaries of the airport surface area&lt;/li&gt;&#xA;&lt;li&gt;The pilot specifically requests it.  &lt;/li&gt;&#xA;&lt;li&gt;The airport is not among those listed in &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/part-91/appendix-D&quot; rel=&quot;nofollow&quot;&gt;14 CFR Part 91, Appendix D&lt;/a&gt; (except helicopters)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the weather is not reported at the airport, the pilot must tell ATC that they are &quot;unable to maintain VFR&quot; and request SVFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note:  The weather conditions that you describe above are technically &quot;Marginal VFR&quot; and not IFR.  It would be a perfect situation to operate SVFR though.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="3504" LastEditDate="2015-01-19T16:27:37.943" LastActivityDate="2015-01-19T16:27:37.943" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="362" PostTypeId="1" AcceptedAnswerId="412" CreationDate="2013-12-25T00:06:17.890" Score="7" ViewCount="4881" Body="&lt;p&gt;Does anyone currently own or have experience flying an &lt;a href=&quot;http://www.iconaircraft.com/&quot; rel=&quot;nofollow&quot;&gt;ICON A5 aircraft&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They claim a range of &lt;strong&gt;300 NM (555.6 km)&lt;/strong&gt;. I would like to know whether this is a theoretical calculated range, or a true/actual number?&lt;/p&gt;&#xA;" OwnerUserId="34" LastEditorUserId="62" LastEditDate="2020-05-22T14:46:34.047" LastActivityDate="2020-05-22T14:46:34.047" Title="What is the actual range of ICON A5?" Tags="&lt;flight-planning&gt;&lt;range&gt;&lt;icon-a5&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="363" PostTypeId="2" ParentId="225" CreationDate="2013-12-25T01:56:35.937" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.fltplan.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;FltPlan.com&lt;/a&gt; has a great airport mapping engine.  Just click on &quot;Nearby Airports&quot; on the main page and enter the location that you want to search around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can search by zip code, city name, or an existing airport id and filter the results by minimum runway length, distance, approach types, and fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example of the results:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SCxmb.jpg&quot; alt=&quot;Nearby Airports 1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WFFI6.jpg&quot; alt=&quot;Nearby Airports 2&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2015-05-03T04:07:59.463" LastActivityDate="2015-05-03T04:07:59.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="364" PostTypeId="2" ParentId="315" CreationDate="2013-12-25T02:02:00.000" Score="4" Body="&lt;p&gt;In Australia aircraft which require the carriage of an ELT are to use a beacon which operates on frequencies 406 and 121.5 MHz. &lt;em&gt;&lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS%3aSTANDARD%3a%3apc=PC_90275&quot; rel=&quot;nofollow&quot;&gt;CASA ELT Regulation Changes&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulation they refer to (CAR 252A) can be viewed in it's current form &lt;a href=&quot;http://www.comlaw.gov.au/Details/F2013C00371/Html/Volume_3#_Toc358291615&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. Part four is as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(4)  For an emergency locator transmitter, emergency position indicating &#xA;           radio beacon or personal locator beacon to be an eligible ELT, it&#xA;           must meet the following requirements:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(a)  it must, if activated, operate simultaneously:&lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(i)  in the frequency band 406 MHz–406.1 MHz; and&lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;(ii)  on 121.5 MHz;&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;    &#xA;    &lt;p&gt;(b)  it must be registered with the Australian Maritime Safety Authority;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(c)  if it is fitted with a lithium‑sulphur dioxide battery—the battery&#xA;                  must be of a type authorised by the FAA in accordance with&#xA;                  TSO‑C142 or TSO‑C142a.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="124" LastEditorUserId="39" LastEditDate="2013-12-25T06:47:39.810" LastActivityDate="2013-12-25T06:47:39.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="365" PostTypeId="5" CreationDate="2013-12-25T02:06:24.473" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2013-12-25T02:06:24.473" LastActivityDate="2013-12-25T02:06:24.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="366" PostTypeId="4" CreationDate="2013-12-25T02:06:24.473" Score="0" Body="Instrument Approach Procedures (IAPs) are procedures used by pilots to maneuver an aircraft by reference to their instruments during an approach, published by the FAA and other third parties (most notably Jeppesen)." OwnerUserId="69" LastEditorUserId="64" LastEditDate="2014-01-27T16:12:29.480" LastActivityDate="2014-01-27T16:12:29.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="367" PostTypeId="1" CreationDate="2013-12-25T02:33:10.180" Score="13" ViewCount="4509" Body="&lt;p&gt;Why do some aircraft require anti-icing on the tail while others (Dassault Falcon Jets, Boeing 737, 747, etc.) don't?&lt;/p&gt;&#xA;" OwnerUserId="186" LastEditorUserId="1696" LastEditDate="2015-02-09T20:56:05.147" LastActivityDate="2015-02-09T22:19:01.293" Title="Why do only some aircraft require tail anti-icing?" Tags="&lt;aerodynamics&gt;&lt;icing&gt;&lt;anti-ice&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="368" PostTypeId="5" CreationDate="2013-12-25T03:56:15.500" Score="0" Body="&lt;p&gt;Air Traffic Control (ATC) refers to a service provided by ground-based controllers who direct and coordinate air traffic in order to improve safety and efficiency. The full ICAO term is Air Traffic Control Service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC is usually provided at a national level by a civilian or military organization (depending on the country) although in some regions there may also be an international ATC organization, such as &lt;a href=&quot;http://www.eurocontrol.int/&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol&lt;/a&gt; in Europe. Depending on local regulations, ATC may provide services to all flights at all times, or to only some flights at certain times or in certain airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC services vary by country and location, but they typically include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ground control, which directs aircraft moving on the ground at an airport&lt;/li&gt;&#xA;&lt;li&gt;Tower control, which directs aircraft on final approach to or taking off from an airport&lt;/li&gt;&#xA;&lt;li&gt;Arrival/Departure control, which directs aircraft arriving in or departing from an airport's local airspace&lt;/li&gt;&#xA;&lt;li&gt;En route control, which directs aircraft as they cruise between airports&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Controllers use radar and other technologies to plan, track and direct air traffic. They communicate instructions to pilots verbally by radio, or - if possible - by &lt;a href=&quot;http://en.wikipedia.org/wiki/Aviation_light_signals&quot; rel=&quot;nofollow&quot;&gt;light gun&lt;/a&gt; in case of radio failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a flight is under ATC control, controllers may provide different types of instructions to pilots, by radio. They may instruct the pilot to fly a specific altitude, heading or speed; clear (authorize) pilots to take off, land or start an instrument approach; or provide other instructions as required. The main purpose of ATC instructions is to avoid collisions by providing adequate separation between aircraft; a secondary, but still important purpose is to improve efficiency by routing flights so as to avoid unnecessary delays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots are usually required to follow all ATC instructions unless there is a critical safety reason not to, but pilots may request ATC to allow an alternative flight path and the pilot always has final authority over the flight. In an emergency, ATC can assist pilots by providing guidance to the nearest airport, directing other air traffic away from the aircraft in distress, giving information about weather conditions and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for all questions about ATC organizations, procedures and interactions between ATC and pilots.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control&quot; rel=&quot;nofollow&quot;&gt;Air traffic control&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/nas/&quot; rel=&quot;nofollow&quot;&gt;National Airspace System&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eurocontrol.int/&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-12-29T18:46:28.517" LastActivityDate="2015-12-29T18:46:28.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="369" PostTypeId="4" CreationDate="2013-12-25T03:56:15.500" Score="0" Body="Air Traffic Control (ATC) is a service of ground-based controllers that directs and coordinates aircraft to improve safety and efficiency." OwnerUserId="69" LastEditorUserId="62" LastEditDate="2014-09-18T00:06:20.357" LastActivityDate="2014-09-18T00:06:20.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="370" PostTypeId="1" AcceptedAnswerId="373" CreationDate="2013-12-25T04:24:06.430" Score="15" ViewCount="2433" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=0a1f56a8c1e2264729257a51649ceabf&amp;amp;node=14:3.0.1.1.11.7.3.2&amp;amp;rgn=div8&quot;&gt;135.293(a)(7)(iii)&lt;/a&gt; requires that pilots be tested on:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) Operating in or near thunderstorms (including best penetrating&#xA;  altitudes), turbulent air (including clear air turbulence), icing,&#xA;  hail, and other potentially hazardous meteorological conditions;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So what are the best penetrating altitudes when forced to operate in a thunderstorm?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most obvious answer is to stay out of it in the first place, but the reg requires us to come up with an answer....&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2018-06-21T18:52:04.090" Title="What is the best altitude to penetrate a thunderstorm?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;far-135&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="371" PostTypeId="1" AcceptedAnswerId="375" CreationDate="2013-12-25T04:28:33.110" Score="17" ViewCount="8391" Body="&lt;p&gt;Most new commercial pilots don't have a lot of flight time, so won't be hired by the airlines or corporate operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of operations require an air carrier certificate (even though they are a &quot;commercial&quot; pilot, they can't just start flying people around)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can they do to build time while (hopefully) getting paid to fly?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-01-13T01:54:49.223" LastActivityDate="2017-08-21T10:48:02.930" Title="What can a new commercial pilot do to build flight time?" Tags="&lt;faa-regulations&gt;&lt;career&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="372" PostTypeId="1" AcceptedAnswerId="48398" CreationDate="2013-12-25T04:51:06.310" Score="16" ViewCount="7333" Body="&lt;p&gt;If ATC gives me a clearance to cross a fix at a specific altitude or a descent at pilot's discretion and I read back the clearance, is my readback considered the report specified in the AIM, or do I have to inform them when I actually start down?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ATpubs/AIM/aim0503.html&quot;&gt;AIM 5-3-3.&lt;/a&gt; Additional Reports&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. The following reports should be made to ATC or FSS facilities&#xA;  without a specific ATC request:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. At all times.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) When vacating any previously assigned altitude or flight level for&#xA;  a newly assigned altitude or flight level.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An Example - Say that a pilot is flying at flight level 340 100 NM from Wilmington VOR and gets the following clearance:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ATC: N1234, cross Wilmington VOR at flight level 240&lt;br&gt;&#xA;  Pilot: Cross Wilmington VOR at flight level 240, N1234&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ATC: N1234, descend at pilot's discretion to flight level 240&lt;br&gt;&#xA;  Pilot: Descend at pilot's discretion to flight level 240  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's a little early to start down since we want to stay high for fuel efficiency, so the pilot decides to wait until 30 NM from the VOR to start down.  When they reach that point, are they required to inform ATC before starting the descent or are they considered to have reported the descent earlier?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hear pilots that do it both ways and each camp is pretty emphatic about it....&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="72" LastEditDate="2014-03-03T05:33:32.357" LastActivityDate="2019-03-26T01:29:27.907" Title="Are you required to report leaving an altitude if you have been given a crossing restriction?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;aim&gt;" AnswerCount="5" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="373" PostTypeId="2" ParentId="370" CreationDate="2013-12-25T04:52:05.157" Score="21" Body="&lt;p&gt;The obvious answer you mentioned should be reiterated: &lt;strong&gt;Avoid thunderstorms whenever possible&lt;/strong&gt;! Just because there are &quot;best penetrating altitudes&quot; doesn't change the fact that thunderstorms are extremely hazardous to aircraft and should be avoided in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that said, the FAA's &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac%2000-24c.pdf&quot;&gt;Advisory Circular 00-24C&lt;/a&gt; mentions that, if unable to avoid penetrating a thunderstorm:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To avoid the most critical icing, establish a penetration altitude below the freezing level or above the level of -15ºC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is to help minimize rapid accumulation of clear ice:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Supercooled water freezes on impact with an aircraft. Clear icing can occur at any &#xA;  altitude above the freezing level but at high levels, icing from smaller droplets may be rime or &#xA;  mixed rime and clear. The abundance of large, supercooled water droplets makes clear icing very &#xA;  rapid between 0ºC and -15ºC, and encounters can be frequent in a cluster of cells. Thunderstorm &#xA;  icing can be extremely hazardous.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another point to mention is that, regardless of there being a recommended &quot;penetration altitude,&quot; it is important to maintain a constant attitude, not altitude:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is almost impossible to hold a constant altitude in a thunderstorm, and maneuvering &#xA;  in an attempt to do so greatly increases stress on the aircraft. Stresses are least if the aircraft is &#xA;  held in a constant attitude. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But again, emphasizing the dangers of thunderstorms, the circular states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Never regard any thunderstorm lightly, even when radar &#xA;  observers report the echoes are of light intensity. Avoiding thunderstorms is the best policy.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Weather recognizable as a thunderstorm should be considered hazardous, &#xA;  as penetration of any thunderstorm can lead to an aircraft accident and fatalities to those on &#xA;  board. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="79" LastActivityDate="2013-12-25T04:52:05.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="374" PostTypeId="2" ParentId="371" CreationDate="2013-12-25T05:24:30.660" Score="3" Body="&lt;p&gt;One of the most common ways to build time is to instruct.  You will need to get your CFI Rating.  I know you can also tow banners, and possibly sky divers (Not too sure on this one.)&lt;/p&gt;&#xA;" OwnerUserId="188" LastActivityDate="2013-12-25T05:24:30.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="375" PostTypeId="2" ParentId="371" CreationDate="2013-12-25T06:20:42.820" Score="20" Body="&lt;p&gt;For a commercial pilot (without a CFI rating) you've got some options, but the real golden goose of time building is flight instructing. Most folks I know who are time-building accumulate the minimum amount of time until they have enough to get the CFI rating, then go out and instruct to get to their end goal (time / types).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the CFI rating, some things to look in to include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Banner Tow (if available in your area)&lt;/li&gt;&#xA;&lt;li&gt;Crop dusting (again, if available in your area)&lt;/li&gt;&#xA;&lt;li&gt;Glider towing &lt;/li&gt;&#xA;&lt;li&gt;Skydiving&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=7721&quot;&gt;The FAA has a page on skydiving operations this that's worth a read.&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Ferry Piloting (if you don't mind the travel)&lt;/li&gt;&#xA;&lt;li&gt;Photo work - anything from costal erosion photos to event coverage depending on your location.&lt;/li&gt;&#xA;&lt;li&gt;News work - Hand in hand with Photo work, but also traffic and the like.&lt;/li&gt;&#xA;&lt;li&gt;Sightseeing flights&lt;br&gt;&#xA;&lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-Commercial-Air-Tour-Charity-and-Sightseeing-Rule.aspx&quot;&gt;AOPA has a page on this which is worth a read&lt;/a&gt;, take care as you almost certainly want to be sure you fall under Part 91 and not Part 135!&lt;/li&gt;&#xA;&lt;li&gt;Deliveries.&lt;br&gt;&#xA;Someone needs a wedding cake moved across the state? You can often do that in a Cessna more efficiently than they can by car, and as a commercial pilot you can even charge for it.&lt;/li&gt;&#xA;&lt;li&gt;Corporate Flight Jobs  &lt;/li&gt;&#xA;&lt;li&gt;Sightseeing within 25sm of an airport&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are some outfits that will &quot;sell&quot; you SIC in their cargo twins. It's a way to build TT, but it's considered an unscrupulous practice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of these will probably require the very time you're looking to build, or experience in specific types of aircraft, but it can't hurt to investigate.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2015-01-14T00:14:56.387" LastActivityDate="2015-01-14T00:14:56.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="376" PostTypeId="2" ParentId="370" CreationDate="2013-12-25T06:33:38.690" Score="6" Body="&lt;p&gt;0 AGL. Do not ever penetrate a thunderstorm in an airplane. It is stupid. People die that way every year.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-25T06:33:38.690" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="378" PostTypeId="2" ParentId="351" CreationDate="2013-12-25T07:06:25.787" Score="9" Body="&lt;p&gt;In areas of large magnetic declination, approaches and runways are given in true instead of magnetic headings, designated by T after the heading, such as RNAV 13T approach. If you are assigned a VOR radial, just follow that radial whether it is true or magnetic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The important thing is that you don't use magnetic headings on a true approach. Look out for that capital T up north.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2013-12-25T07:06:25.787" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="379" PostTypeId="2" ParentId="51" CreationDate="2013-12-25T07:38:46.200" Score="5" Body="&lt;p&gt;A rotor on an aircraft/rotorcraft is basically an airfoil section twisted along its length. This twist is also known as the pitch, and in most cases it is variable. On approaching Mach 1 or the speed of sound, shock waves begin to form on an aircraft (eg. on the wings)  and there is a sharp rise in drag (known as wave drag). This is due to the fact that at high speeds, the airflow can no longer be treated as incompressible flow. The rotors face the same compressibility effects that an aircraft wing  faces near the speed of sound, hence it isn't able to overcome this drag.&lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="189" LastEditDate="2013-12-28T17:16:09.903" LastActivityDate="2013-12-28T17:16:09.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="380" PostTypeId="2" ParentId="348" CreationDate="2013-12-25T09:56:00.480" Score="3" Body="&lt;p&gt;The aim of parallel isobars on the wing is to generate quasi two-dimensional flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say, the layout is set. You shaped the wing in a way to 'force' the isobars to be parallel with the sweep - the entire span.&#xA;You now (should) have the same pressure distribution in every single profile of your wing. This eases your calculations extremely!&lt;/p&gt;&#xA;" OwnerUserId="190" LastActivityDate="2013-12-25T09:56:00.480" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="381" PostTypeId="1" CreationDate="2013-12-25T12:57:54.160" Score="13" ViewCount="1299" Body="&lt;p&gt;I know that the F-16 (F-16I and Block 50/52/60 models) have conformal fuel tanks standard now on top of the wing/fuselage area.  The Silent Eagle model of the F-15E proposed by Boeing for South Korea, and other F-15E customers had them added.  The F-18E (Superhornet) has demoed a set recently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on older aircraft, how common were conformal fuel tanks?  Or have they always been drop tanks before?&lt;/p&gt;&#xA;" OwnerUserId="80" LastEditorUserId="39" LastEditDate="2015-04-16T16:44:32.043" LastActivityDate="2015-05-11T20:32:38.487" Title="How common are conformal fuel tanks?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="382" PostTypeId="1" CreationDate="2013-12-25T16:19:36.073" Score="13" ViewCount="3901" Body="&lt;p&gt;We are working on a UAV and will soon get to the testing phase. We intend to fly at a maximum altitude of 300-400 meters. I wanted to know as to what restrictions apply to the airspace in India (specifically Delhi) with respect to flying UAVs as well as the altitudes from which they apply?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We will also be testing autonomous capabilities. Do we need to get any licenses for this?&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="72" LastEditDate="2015-01-24T08:29:13.257" LastActivityDate="2015-05-13T10:27:19.827" Title="What restrictions apply to flying RC and UAV planes in India at very low altitudes?" Tags="&lt;airspace&gt;&lt;unmanned-aerial-vehicle&gt;&lt;dgca-india-regulations&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="383" PostTypeId="1" AcceptedAnswerId="384" CreationDate="2013-12-25T19:20:23.417" Score="6" ViewCount="6023" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.13&amp;amp;idno=14#14:2.0.1.3.13.1.9.2&quot;&gt;FAR 91.3&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft approach category means a grouping of aircraft based on a&#xA;  speed of VREF, if specified, or if VREF is not specified, 1.3 Vso at&#xA;  the maximum certificated landing weight. VREF, Vso, and the maximum&#xA;  certificated landing weight are those values as established for the&#xA;  aircraft by the certification authority of the country of registry.&#xA;  The categories are as follows—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Category A: Speed less than 91 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Category B: Speed 91 knots or more but less than 121 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Category C: Speed 121 knots or more but less than 141 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Category D: Speed 141 knots or more but less than 166 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Category E: Speed 166 knots or more.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So an aircraft category never changes because it is always Vref at max landing weight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What if I fly an approach at a speed that falls into a different category?  For instance, a jet may land at significantly less than this speed if very light, or more than this speed if landing with less than full flaps due to a failure (or any other operational reason).  Which minimums do you use then?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-25T19:28:19.113" Title="Which approach category minimums should I use when conducting an instrument approach?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="384" PostTypeId="2" ParentId="383" CreationDate="2013-12-25T19:20:23.417" Score="9" Body="&lt;p&gt;According to the FAA Safety Alert for Operators issued on 09/20/2012 (&lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2012/SAFO12005.pdf&quot;&gt;SAFO 12005&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A pilot may never use the approach minimums specified for an approach category lower than their certified approach category, even if the actual approach is flown at a speed that would be in the lower approach category.&lt;/li&gt;&#xA;&lt;li&gt;A pilot must always use the approach minimums specified for an approach category higher than their certified approach category if the actual approach will be flown at a speed that would be in the higher approach category. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that this is different in other areas of the world (Canada for example uses the actual approach speed of the aircraft to determine the approach category).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-25T19:28:19.113" LastActivityDate="2013-12-25T19:28:19.113" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="385" PostTypeId="2" ParentId="312" CreationDate="2013-12-25T19:50:04.907" Score="20" Body="&lt;p&gt;For simplicity, assume a single-engine plane with a two-blade propeller. Just imagine an aircraft is perfectly level and moving forward through the air. The angle of attack on both blades of the propeller would be the same. Now imagine the plane pitches up a bit. One blade's angle of attack will increase and other will decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ap2Or.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2011/December/feature-rudder.html&quot;&gt;AOPA.org&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Within reason, the greater the angle of attack, the greater the thrust generated. So one blade (or, to be more precise, a blade on one side of the aircraft) will generate more thrust than the other.&lt;/p&gt;&#xA;" OwnerUserId="195" LastEditorUserId="3201" LastEditDate="2015-06-14T13:29:51.610" LastActivityDate="2015-06-14T13:29:51.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="386" PostTypeId="2" ParentId="311" CreationDate="2013-12-25T19:53:15.730" Score="-5" Body="&lt;p&gt;Near the ground, the ground can push up on the airplane, giving it more lift.&lt;/p&gt;&#xA;" OwnerUserId="195" LastActivityDate="2013-12-25T19:53:15.730" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="387" PostTypeId="2" ParentId="347" CreationDate="2013-12-25T21:55:33.870" Score="16" Body="&lt;p&gt;I'm going to be referring to &lt;a href=&quot;http://www.avweb.com/news/maint/182846-1.html&quot; rel=&quot;noreferrer&quot;&gt;an old AvWeb article by Mike Busch&lt;/a&gt; with my links in this post.&lt;br /&gt;&#xA;As with most of what Mike writes, it's worth a good read.&lt;/p&gt;&#xA;&lt;h1&gt;Why is Pre-Heating Important?&lt;/h1&gt;&#xA;&lt;p&gt;Pre-heating your engine in the winter is important for a bunch of reasons, but there are two main ones that should get your attention - the first is preventing &lt;em&gt;metal-on-metal wear&lt;/em&gt; by ensuring all parts have adequate clearances to function, and the second is improving &lt;em&gt;lubrication&lt;/em&gt; by making sure your oil is ready to flow, and the spaces it's going to flow in to are opened up enough to let the oil in.&lt;/p&gt;&#xA;&lt;h2&gt;Metal-on-Metal Wear&lt;/h2&gt;&#xA;&lt;p&gt;Starting a piston engine is responsible for most of the wear the engine sees in its life - surfaces which have long since had their protective coatings of oil drip off are banging together while you crank the engine, and for a few seconds after startup until the oil pump can build up pressure and splash lubrication in the crank case can thoroughly coat the other moving parts.&lt;/p&gt;&#xA;&lt;p&gt;In the case of a truly &lt;em&gt;cold&lt;/em&gt; start there's an additional complication: like &lt;a href=&quot;https://aviation.stackexchange.com/a/356/64&quot;&gt;2NinerRomeo points out&lt;/a&gt;, different metals in your engine have different coefficients of thermal expansion, and you have steel (probably several alloys), aluminum, brass, and a few others in your powerplant. &lt;a href=&quot;http://www.avweb.com/news/maint/182846-1.html?redirected=1#bearings&quot; rel=&quot;noreferrer&quot;&gt;When cold the clearances between these metals can be so tight that the additional wear is substantial&lt;/a&gt;, and at a certain point you may even damage the engine by attempting a start, shaving or spinning bearings and scuffing cylinder walls with the rapidly expanding pistons once the engine fires.&lt;/p&gt;&#xA;&lt;h2&gt;Lubrication&lt;/h2&gt;&#xA;&lt;p&gt;The other factor to consider in a cold start is lubrication - both the oil doing the lubricating, and the spaces into which it needs to flow.&lt;/p&gt;&#xA;&lt;p&gt;Take the dipstick out of a cold engine and you will marvel at how the oil just clings there in a thick layer (this is especially true of heavy single-grade oil like 100W, but even 15W50 starts getting very sticky down in the 30°F-35°F range).  Oil that has thickened up from the cold doesn't pump very well - your engine may take a longer than normal time to develop oil pressure, and narrow spaces may get little to no lubrication until the oil has heated (and thinned) enough to get through the narrower oil galleys and tight spaces between some components.&lt;/p&gt;&#xA;&lt;p&gt;Those tight spaces, as I mentioned under Metal-on-Metal Wear, tend to be tighter when it's cold, which means it's even harder for oil to work its way in and build up a good film of fluid. Until that film is built up and doing its job your engine is really &lt;em&gt;inadequately lubricated&lt;/em&gt;, even if it's running. (Check out the webinar video in 2NinerRomeo's answer where Mike Busch goes into a lot of detail on how oil works, he has a nice explanation of the fluid film lubrication process.)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;How do I make sure I do my preheat right?&lt;/h1&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/maint/182846-1.html?redirected=1#finest&quot; rel=&quot;noreferrer&quot;&gt;The best preheat possible is spending the night in a nice, warm, heated hangar.&lt;/a&gt; It basically guarantees that every part of your aircraft has been brought up to the same temperature, and even affords you a nice place to preflight as opposed to doing it out on the ramp in the 6-but-feels-like-60 knot winter winds.&lt;/p&gt;&#xA;&lt;p&gt;A hangar preheat isn't just the best for your engine -- your gyro instruments get brought up to a nice warm temperature (remember, mechanical gyros have to spin up, and they have the same issues as your engine did in terms of clearances being reduced by the cold), and the ship's battery gets warmed up too so it's ready to provide its best possible cranking current.&lt;/p&gt;&#xA;&lt;h3&gt;I don't have a hangar you insensitive clod!&lt;/h3&gt;&#xA;&lt;p&gt;Unfortunately some of us (like ME) don't have hangars - heated or otherwise - or our local FBO charges a hefty sum to spend the night in the warm. Those of us without hangars have to make due with a ramp pre-heat of some kind.  I'm going to assume you're in the same boat as me (no hangar, no electricity), and have to use some other technique.&lt;/p&gt;&#xA;&lt;p&gt;Most ramp pre-heats where you have neither a hangar nor electricity take the form of a &lt;a href=&quot;http://www.avweb.com/news/maint/182846-1.html?redirected=1#hotair&quot; rel=&quot;noreferrer&quot;&gt;&amp;quot;forced hot air&amp;quot; system&lt;/a&gt; - either one wheeled around by the FBO, or portable ones powered by propane. &lt;a href=&quot;http://www.aircraftspruce.com/catalog/eppages/ncpreheater.php&quot; rel=&quot;noreferrer&quot;&gt;There are even ones built around a camp stove&lt;/a&gt; which are deceptively good at the job (and in a pinch can burn the avgas you drained checking your tanks for water).&lt;/p&gt;&#xA;&lt;p&gt;The general procedure for a forced-hot-air preheat is to point the heat into the cowl's cooling inlets, letting the warm air flow over and around the engine and out the cooling outlets. Start the heater up before your preflight, and with a little luck by the time you're done with the walk-around your engine will be ready to start.&lt;br /&gt;&#xA;If it's extremely cold you may want to block part of the inlets and put a blanket over the cowling during the pre-heat to help keep the heat trapped on the engine, and as 2NinerRomeo points out, when using a high-intensity heat source like a propane heater make sure you don't pump so much heat into the cowling that you blister your paint.  A gradual warm-up is what you want - we're slow-roasting the engine, not broiling it.&lt;/p&gt;&#xA;&lt;h2&gt;How do I know the preheat is &amp;quot;done&amp;quot;?&lt;/h2&gt;&#xA;&lt;p&gt;There are three common ways to tell if your preheat has had enough time to adequately warm your engine - each technique works pretty well, and you can use whichever makes the most sense for your situation.&lt;/p&gt;&#xA;&lt;h3&gt;Testing by feel&lt;/h3&gt;&#xA;&lt;p&gt;This is classic if you have a cowling that can be easily opened like most Piper aircraft, just feel all of your cylinders and the crankcase. They should, if your preheat was thorough enough, all be slightly warm to the touch. It's low-tech, but it works well if you can use it.&lt;br /&gt;&#xA;As a practical matter it's usually easier to tell if the &amp;quot;top end&amp;quot; (cylinders) are ready this way than it is the &amp;quot;bottom end&amp;quot; crank case / crankshaft / bearings), but with some cowlings (many Cessnas, or my Cherokee 180) you're simply not getting your hand in there to feel the engine: you can reach the front cylinders and a bit of the case, but the aft half of the engine is basically inaccessible without taking the cowling apart (and losing all that trapped heat).&lt;/p&gt;&#xA;&lt;h3&gt;Testing with the dipstick&lt;/h3&gt;&#xA;&lt;p&gt;Another good indicator is that when you take the dipstick out of the engine the oil flows off nicely -- compare with how thick and syrupy the oil was in the cold engine and is should be obvious when it's &amp;quot;ready&amp;quot;.&lt;br /&gt;&#xA;This works for pretty much every engine, even if the only access you have is the little oil door, but it's also one of the slowest &amp;amp; most conservative indicators: pretty much all the thermal mass of the engine needs to heat up before the oil in the sump is going to get warmed up and start to loosen up.&lt;/p&gt;&#xA;&lt;h3&gt;Checking with your instruments&lt;/h3&gt;&#xA;&lt;p&gt;The final way to check the status of your preheat is to check your engine instruments: If your cylinder head temperatures are all reading something reasonable (say 60-70F) and your oil temperature is at least &amp;quot;off the peg&amp;quot; your engine has been thoroughly heated.&lt;br /&gt;&#xA;This technique is a little instrumentation-dependent though -- some engines may not show an oil temperature indication until you get your oil up into the 90 degree range (which would be great for start-up, but lousy for sitting on the ramp waiting). For those engines you probably want to use the dip stick test to check if the oil is &amp;quot;ready&amp;quot;.&lt;br /&gt;&#xA;This technique also works best if you have individual cylinder probes, as you can determine if your engine has been evenly heated (this is especially true of longer engines, like a 6-cylinder powerplant: if the front cylinders have been getting blasted with warm air and are in the 90s, but the rear cylinders are still reading 30 degrees you may need to adjust your preheat procedure to warm those rear cylinders!)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Parting Thoughts - Stuff outside the engine compartment?&lt;/h1&gt;&#xA;&lt;p&gt;I've concentrated mostly on pre-heating the engine, which is what most people think about when they think about pre-heating aircraft, but as I mentioned briefly it's worth noting that other parts of the aircraft benefit from pre-heating too.&lt;/p&gt;&#xA;&lt;p&gt;For example, a warm battery (60-70°F) will crank better than a cold one. If your battery is in the engine compartment it will get warmed up during your preheat, otherwise you should be aware that cold starting puts a pretty heavy demand on the battery, and your battery will appreciate if you limit cranking as much as practical.&lt;/p&gt;&#xA;&lt;p&gt;Similarly, your gyro instruments (turn &amp;amp; bank, directional gyro, attitude indicator) will all need to spin up - that happens in a hurry (as soon as you hit the master for the electric ones, as soon as the engine catches and the vacuum pump starts really spinning for the vacuum driven ones).&lt;br /&gt;&#xA;If you can direct some warm air into the cabin your gyro instruments will thank you (and you'll probably thank yourself - those control yokes are COLD!). The gyros take less of a beating than your engine, and certainly cost less to replace when they wear out, but keeping them happy is worth a little effort.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-27T15:24:24.280" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="388" PostTypeId="2" ParentId="381" CreationDate="2013-12-25T22:45:39.407" Score="8" Body="&lt;p&gt;Technically speaking, &lt;a href=&quot;http://en.wikipedia.org/wiki/Conformal_fuel_tank&quot;&gt;conformal tanks&lt;/a&gt; don't take up hardpoints, so I'm not sure what we have today has an equivalent in older designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, I'd say somewhat common; streamlined fuel tanks and other conformal packages have been used for quite a while in several different designs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some World War II Supermarine Spitfires used what was called a &quot;&lt;a href=&quot;https://www.google.com/search?q=spitfire+slipper+fuel+tank&amp;amp;tbm=isch&quot;&gt;slipper tank&lt;/a&gt;&quot; - a streamlined package of up to 90 gallons (&lt;a href=&quot;http://en.wikipedia.org/wiki/Supermarine_Spitfire_%28late_Merlin-powered_variants%29&quot;&gt;additional source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The early 1960s-era &lt;a href=&quot;http://en.wikipedia.org/wiki/English_Electric_Lightning&quot;&gt;English Electric Lightning&lt;/a&gt; used a 'conformal ventral store' that could hold either a fuel tank or rocket engine (?!). The Gloster Javelin used a similar set of &quot;&lt;a href=&quot;http://it.wikipedia.org/wiki/File:Gloster_Javelin.svg&quot;&gt;bosom tanks&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-04-16T16:43:47.400" LastActivityDate="2015-04-16T16:43:47.400" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="389" PostTypeId="1" AcceptedAnswerId="2032" CreationDate="2013-12-25T23:01:01.503" Score="16" ViewCount="11855" Body="&lt;p&gt;When flying a domestic US flight, an alternate airport is not required unless the weather is below specific minimums at the destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the rules when on an international flight plan and leaving or returning to the US?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In larger airplanes, carrying the extra fuel required to fly to an alternate (which costs money) is a little silly when there isn't a cloud in the sky and there are multiple airports in the vicinity of your destination that can be easily reached with your already required 45 minute IFR reserve.  We should always have a plan for when things go wrong, but if it can be done safely, is it &lt;strong&gt;&lt;em&gt;legal&lt;/em&gt;&lt;/strong&gt; to file an international flight plan without an alternate? &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="72" LastEditDate="2014-03-03T07:46:01.160" LastActivityDate="2014-09-11T21:24:26.517" Title="Is an alternate airport always required when flying internationally?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;&lt;icao&gt;" AnswerCount="5" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="390" PostTypeId="1" AcceptedAnswerId="403" CreationDate="2013-12-25T23:49:24.553" Score="15" ViewCount="2078" Body="&lt;p&gt;The major reason that lead &lt;a href=&quot;http://en.wikipedia.org/wiki/Kid_in_the_cockpit&quot;&gt;Aeroflot Flight 593&lt;/a&gt; to crash was the partial disengagement of the of autopilot (by the pilot's kid who was in the cockpit) which could have been avoided if the pilots were more familiar with the Airbus 310-100 or there was an audible alert. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do new Airbus aircrafts have an audible alert in such cases now? were the old ones some how altered to implement this?&lt;/p&gt;&#xA;" OwnerDisplayName="user197" LastEditorUserId="1696" LastEditDate="2016-06-14T16:52:57.320" LastActivityDate="2016-06-14T16:52:57.320" Title="Did Airbus add an audible alert when the autopilot partially disengage after the crash of Aeroflot Flight 593?" Tags="&lt;accidents&gt;&lt;autopilot&gt;&lt;airbus&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="391" PostTypeId="1" CreationDate="2013-12-25T23:59:26.217" Score="14" ViewCount="3600" Body="&lt;p&gt;Uncontrolled cabin fires only need a few minutes to spread throughout the cabin of an aircraft, killing everyone onboard and destroying the airframe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, we all know that depressurization and fire do not combine; the lack of oxygen will eliminate one of the elements necessary to keep the fire alive. So if an aircraft had a way to depressurize the cabin and eliminate oxygen in the event of a fire, the fire would be extinguished, saving lives. Of course this applies to flights above 14,000 ft. I know that depressurization is dangerous but there is a better chance of surviving a depressurization than surviving flames.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does a mechanism exist to depressurize the aircraft in case of uncontrolled fire in the cabin? If so, under what circumstances would it be used?&lt;/p&gt;&#xA;" OwnerDisplayName="user197" LastEditorUserId="97" LastEditDate="2014-01-28T17:33:04.690" LastActivityDate="2015-08-21T06:01:49.683" Title="Should depressurization be considered in the event of an inflight cabin fire?" Tags="&lt;emergency&gt;&lt;cabin-pressure&gt;&lt;fire&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="392" PostTypeId="2" ParentId="391" CreationDate="2013-12-26T00:07:31.360" Score="10" Body="&lt;p&gt;Some aircraft do have a manual decompression button which can be used by the pilot in a situation like this.  Keep in mind however that it will only help until the pilot descends (which you will want to do asap in order to land) and the air isn't as thin.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is very important for the crew to get on the ground as rapidly as possible, and simultaneously attempt to put out the fire in order to minimize the amount of damage that can be done.  The single biggest factor in an aircraft fire is how much time elapses before they land and can evacuate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if the cabin depressurizes, typically the oxygen masks deploy automatically which when combined with a fire can have even more disastourous results.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-26T00:38:21.090" LastActivityDate="2013-12-26T00:38:21.090" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="393" PostTypeId="5" CreationDate="2013-12-26T01:34:04.917" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://www.dgca.nic.in/&quot; rel=&quot;nofollow&quot;&gt;Directorate General of Civil Aviation&lt;/a&gt; is the aviation regulatory body in India. Flight rules and certification requirements are promulgated by that agency.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="64" LastEditDate="2014-07-08T19:46:27.370" LastActivityDate="2014-07-08T19:46:27.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="394" PostTypeId="4" CreationDate="2013-12-26T01:34:04.917" Score="0" Body="Questions dealing with regulations promulgated by India's Directorate General of Civil Aviation (DGCA)" OwnerUserId="-1" LastEditorUserId="64" LastEditDate="2014-07-08T19:46:27.370" LastActivityDate="2014-07-08T19:46:27.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="395" PostTypeId="2" ParentId="390" CreationDate="2013-12-26T02:04:35.940" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a12000e19229ed17c8feeeb9bf80fa9d&amp;amp;node=14:1.0.1.3.11&amp;amp;rgn=div5#14:1.0.1.3.11.6.193.16&quot; rel=&quot;nofollow&quot;&gt;14 CFR 25.1329 - Flight guidance system&lt;/a&gt; (which the Airbus must conform to in order to receive FAA approval) requires that all transport category aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(j) Following disengagement of the autopilot, a warning (visual and&#xA;  auditory) must be provided to each pilot and be timely and distinct&#xA;  from all other cockpit warnings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, all transport category airplanes certified by the FAA have a visual and auditory alert when the autopilot is disengaged.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-27T01:08:53.903" LastActivityDate="2013-12-27T01:08:53.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="396" PostTypeId="1" CreationDate="2013-12-26T03:10:59.913" Score="6" ViewCount="1169" Body="&lt;p&gt;This is related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/382&quot;&gt;my earlier question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delhi has a lot of areas with restricted airspace and no fly zones. Assuming we are able to get the necessary licenses and permissions to fly, what should we do if we accidentally enter no fly zones while in controlled flight? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude will be less than 400 meters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once (and if) we are clear of the no fly zone, where should we report the incident? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;This is a hypothetical question. I do not intend to break any laws knowingly.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-12-14T21:02:52.730" Title="What protocol should be followed after accidentally entering restricted airspace with a UAV?" Tags="&lt;airspace&gt;&lt;unmanned-aerial-vehicle&gt;&lt;dgca-india-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="397" PostTypeId="2" ParentId="367" CreationDate="2013-12-26T03:30:06.300" Score="10" Body="&lt;p&gt;Some airplanes don't need the horizontal stabilizer to have anti-ice because it was shown during flight testing that there were no adverse effects from having ice on the tail.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is mainly because the horizontal stabilizer/elevator has been designed so that even with a degradation of lift due to the ice, it still produces a sufficient tail down force to maintain control, even when approaching the stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplanes that do have anti-ice usually either have smaller horizontal stabilizers or (on some older designs) couldn't get the FAA to sign off on a design without it.  Some designs are also more prone to collecting ice (based mainly on the radius of the leading edge) so must demonstrate sufficient handling qualities with even more ice, which may not be possible.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-26T03:35:17.500" LastActivityDate="2013-12-26T03:35:17.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="398" PostTypeId="2" ParentId="396" CreationDate="2013-12-26T05:07:42.500" Score="7" Body="&lt;p&gt;Well this one I can answer even without being an expert on India's airspace regulations: Entering a &quot;no-fly zone&quot; or other restricted area with an aircraft - even an unmanned one - is going to be &lt;em&gt;some kind of a violation&lt;/em&gt;.&#xA;You local authorities could tell you what kind, but it doesn't matter: it's a situation to be entirely avoided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should plan your test flights to occur far, &lt;strong&gt;&lt;em&gt;far&lt;/em&gt;&lt;/strong&gt; away from such restricted areas (as well as from airports, population centers, &quot;open-air gatherings of people&quot; (to use the FAA's parlance), or anything else that you might disturb, damage, destroy, or annoy during your testing.&lt;br&gt;&#xA;This is almost certainly what the DGCA is going to tell you if you contact them and ask for advice on test parameters for an Unmanned Aerial Vehicle, but more importantly it's just &lt;em&gt;plain good old fashioned Common Sense!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you cannot exercise such common sense you should rethink &amp;amp; rework your plans until you can.&lt;br&gt;&#xA;If after &lt;em&gt;real, honest rethinking&lt;/em&gt; you're still in a situation where you feel you may inadvertently penetrate controlled or restricted airspace then coordinate with the agencies that handle that airspace &lt;strong&gt;&lt;em&gt;PRIOR TO YOUR TESTING&lt;/em&gt;&lt;/strong&gt; to make appropriate arrangements.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now if you exercised all due common sense and still the absolute worst happens (Murphy's law rears its ugly head and LITERALLY everything that can go wrong does - even the engine cutoff and the emergency self-destruct didn't work!) you may still accidentally wander into airspace you shouldn't be in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that DOES happen your procedures &lt;em&gt;should&lt;/em&gt; be effectively the same as they are in a manned aircraft anywhere in the world if you encounter the same situation: &lt;strong&gt;Communicate, Confess,&lt;/strong&gt; and &lt;strong&gt;&lt;em&gt;Comply&lt;/em&gt;&lt;/strong&gt;.&lt;br&gt;&#xA;Contact the controlling authority (e.g. tower, approach, the military division responsible, etc.), let them know what's happened, tell them &lt;em&gt;where you are&lt;/em&gt; (in this case, where your drone is - they'll likely ask you to copy a number if they want to find out where &quot;home base&quot; is), and comply with any instructions they give you.&lt;br&gt;&#xA;(This may mean you need a radio and a list of frequencies on the ground with you - picking up a sectional chart would be a good idea. You may also need a radio-relay in your UAV depending on what kind of range the vehicle has...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, the controller might get a little snippy with you (you are after all somewhere you're not supposed to be. Controllers tend to not like that!), and you might get in a little trouble for the violation (because again, you're somewhere you're not supposed to be), but that's all preferable to the potential alternative of smacking your UAV into a plane full of people at 300 feet on short final to Indira Gandhi International Airport.&lt;br&gt;&#xA;As with all aviation operations, safety &lt;em&gt;must&lt;/em&gt; be your overriding concern. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-26T05:07:42.500" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="399" PostTypeId="5" CreationDate="2013-12-26T05:49:46.820" Score="0" Body="&lt;p&gt;Piston aircraft engines are &lt;a href=&quot;http://en.wikipedia.org/wiki/Reciprocating_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;reciprocating&lt;/a&gt; internal combustion engines, similar to the type found most automobiles, which are used as powerplants in some aircraft, generally driving a propeller either directly or through a reduction-drive gearbox.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These engines are typically gasoline-powered, &lt;a href=&quot;http://en.wikipedia.org/wiki/Avgas&quot; rel=&quot;nofollow noreferrer&quot;&gt;burning some form of AvGas or automotive gasoline&lt;/a&gt;, though some &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_diesel_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft diesel engines&lt;/a&gt; exist, which can burn diesel fuel or jet fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first successful powered aircraft all used piston engines, which remained ubiquitous on aircraft of all sizes through the early-to-mid-1950s.  However, the first workable &lt;a href=&quot;/questions/tagged/jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet&lt;/a&gt;s were built and placed into military service during World War II, and the raw speed of jets and their ability to use practically any combustible liquid as &lt;a href=&quot;/questions/tagged/fuel&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel&lt;/a&gt; led them to quickly eclipse piston engines in &lt;a href=&quot;/questions/tagged/fighter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fighter&amp;#39;&quot; rel=&quot;tag&quot;&gt;fighter&lt;/a&gt; aircraft (with &lt;a href=&quot;/questions/tagged/bomber&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bomber&amp;#39;&quot; rel=&quot;tag&quot;&gt;bomber&lt;/a&gt;s following soon afterward).  The first &lt;a href=&quot;/questions/tagged/jet-airliner&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-airliner&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-airliner&lt;/a&gt; (the &lt;a href=&quot;/questions/tagged/de-havilland-comet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;de-havilland-comet&amp;#39;&quot; rel=&quot;tag&quot;&gt;de-havilland-comet&lt;/a&gt;) entered commercial service in 1952, and the first widely-successful jetliner (the &lt;a href=&quot;/questions/tagged/boeing-707&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-707&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-707&lt;/a&gt;) carried its first paying passengers in 1958; the large piston-engined airliners of the 1940s and 1950s, such as the &lt;a href=&quot;/questions/tagged/lockheed-constellation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lockheed-constellation&amp;#39;&quot; rel=&quot;tag&quot;&gt;lockheed-constellation&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/dc-7&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-7&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-7&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/boeing-377-stratocruiser&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-377-stratocruiser&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-377-stratocruiser&lt;/a&gt;, fell almost entirely out of frontline passenger service by the end of the 1960s.  Even for small, short-haul aircraft (where a jet's high speed provides little advantage, and its high fuel consumption provides a considerable &lt;em&gt;disadvantage&lt;/em&gt;), piston engines were progressively replaced by &lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt;s, due to the latter's vastly-higher &lt;a href=&quot;/questions/tagged/reliability&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;reliability&amp;#39;&quot; rel=&quot;tag&quot;&gt;reliability&lt;/a&gt; (large piston engines, with their many cylinders, valves, pistons, sparkplugs, etc., are notoriously prone to suffering &lt;a href=&quot;/questions/tagged/engine-failure&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine-failure&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine-failure&lt;/a&gt;s) and their ability to run on the same fuels used for large jet aircraft.  Since at least 1970, the main niche for piston engines in aviation has been small &lt;a href=&quot;/questions/tagged/general-aviation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;general-aviation&amp;#39;&quot; rel=&quot;tag&quot;&gt;general-aviation&lt;/a&gt; aircraft, as small piston engines are much more reliable than their larger counterparts, and turbine engines scale down poorly to very small sizes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other powerplant types include:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt; - a turbine engine driving a propeller.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt; - a turbine engine producing thrust directly&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2019-07-29T12:03:52.890" LastActivityDate="2019-07-29T12:03:52.890" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="400" PostTypeId="4" CreationDate="2013-12-26T05:49:46.820" Score="0" Body="Piston (reciprocating) aircraft engines are internal combustion engines, similar to the type found in most automobiles. They are typically gasoline powered." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-10T19:20:43.183" LastActivityDate="2014-01-10T19:20:43.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="401" PostTypeId="5" CreationDate="2013-12-26T06:00:26.967" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;https://easa.europa.eu&quot; rel=&quot;nofollow&quot;&gt;European Air Safety Agency (EASA)&lt;/a&gt; is the European agency responsible for regulation of aviation and investigation of aviation accidents/incidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EASA is based in Cologne, Germany. Its &lt;a href=&quot;http://easa.europa.eu/what-we-do.php&quot; rel=&quot;nofollow&quot;&gt;responsibilities broadly include&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Expert advice to the EU for drafting new legislation&lt;/li&gt;&#xA;&lt;li&gt;Implementing and monitoring safety rules, including inspections in the Member States;&lt;/li&gt;&#xA;&lt;li&gt;Type certification of aircraft and components&lt;/li&gt;&#xA;&lt;li&gt;Authorization of third-country (non EU) operators&lt;/li&gt;&#xA;&lt;li&gt;Safety analysis and research.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Appropriate questions for this tag would include those activities which require working directly with the EASA, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Certification&lt;/li&gt;&#xA;&lt;li&gt;Approval&lt;/li&gt;&#xA;&lt;li&gt;Manual Approvals/Acceptance/Revisions&lt;/li&gt;&#xA;&lt;li&gt;Filling out and submitting various forms&lt;/li&gt;&#xA;&lt;li&gt;Rulemaking Process&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Related Tags&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/easa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;easa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;easa-regulations&lt;/a&gt; EASA Regulations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="69" LastEditDate="2014-01-18T17:16:49.363" LastActivityDate="2014-01-18T17:16:49.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="402" PostTypeId="4" CreationDate="2013-12-26T06:00:26.967" Score="0" Body="EASA is the European Air Safety Agency, a joint regulatory and investigative body responsible for both aviation regulations in the European Community *and* the investigation of accidents and incidents which occur in the European Community or which involve aircraft designs certificated by EASA." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-30T21:52:35.820" LastActivityDate="2013-12-30T21:52:35.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="403" PostTypeId="2" ParentId="390" CreationDate="2013-12-26T06:01:35.203" Score="18" Body="&lt;p&gt;All Airbus aircraft from the A320 onwards currently do not have an method of disabling lateral or pitch control without the full disconnection of the autopilot. In the case that one of the controls fail, the autopilot will also disconnect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the autopilot disconnecting fully, Airbus aircraft have an audible &quot;cavalry charge&quot; which sounds for 3 seconds if disconnected normally, and continuously (until cancelled) if due to a failure or a non-standard method of disconnecting the autopilot.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2013-12-26T13:07:19.350" LastActivityDate="2013-12-26T13:07:19.350" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="404" PostTypeId="5" CreationDate="2013-12-26T06:09:11.447" Score="0" Body="&lt;p&gt;Reduced Vertical Separation Minimum (RVSM) is a class of operations which allow aircraft between FL290 and FL410 to operate with 1000 feet of vertical separation, rather than the 2000 foot minimum separation previously required. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;RVSM operations are an ICAO standard which may be implemented by individual regulating authorities. When implemented, aircraft operating in RVSM airspace are required to have specially certified altimeters and autopilots which meet specific performance requirements for safety when operating with reduced vertical separation.   For specific equipment requirements consult each regulating authority's requirements and equipment certification information.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-30T21:53:00.057" LastActivityDate="2013-12-30T21:53:00.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="405" PostTypeId="4" CreationDate="2013-12-26T06:09:11.447" Score="0" Body="Reduced Vertical Separation Minimum (RVSM) is a class of operations which allow aircraft between FL290 and FL410 to operate with 1000 feet of vertical separation, rather than the 2000 foot minimum separation previously required. " OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-30T21:50:58.153" LastActivityDate="2013-12-30T21:50:58.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="406" PostTypeId="1" AcceptedAnswerId="407" CreationDate="2013-12-26T06:22:33.677" Score="33" ViewCount="26233" Body="&lt;p&gt;I've read that ICAO defines Class F airspace but the FAA has chosen not to use the airspace class in the US. What is the ICAO definition of Class F airspace and how does it differ from other airspace classes? What countries use Class F airspace? Why does the FAA only use A-E and G?&lt;/p&gt;&#xA;" OwnerUserId="79" LastEditorUserId="22726" LastEditDate="2018-05-10T19:54:39.410" LastActivityDate="2018-05-10T19:54:39.410" Title="What is Class F airspace, and why is it not used in the US?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;airspace&gt;&lt;icao&gt;&lt;class-f-airspace&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="407" PostTypeId="2" ParentId="406" CreationDate="2013-12-26T06:54:26.563" Score="31" Body="&lt;p&gt;ICAO Class F airspace is a bit of an odd duck (and the US FAA is apparently not the only agency that thinks so - from a quick check on &lt;a href=&quot;http://en.wikipedia.org/wiki/Airspace_class&quot;&gt;Wikipedia&lt;/a&gt; it seems more jurisdictions ignore class F than implement it. They only mention Class F as being in use in Germany and the UK).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a functional/regulatory standpoint Class F is a sort of hybrid between &quot;Class E&quot; controlled airspace and &quot;Class G&quot; (fully) uncontrolled airspace:&lt;br&gt;&#xA;Class F airspace is designated as &quot;uncontrolled&quot;, but you can get ATC clearances in Class F airspace just like in controlled airspace. The catch is they're &quot;advisory only&quot; (so you don't &lt;em&gt;have&lt;/em&gt; to comply with them, and all the weight is on the pilot's shoulders ). Similarly ATC will provide separation services to IFR flights in Class F airspace, but they do so &quot;where possible&quot;, which means they might tell you they can't provide that service and you're on your own with see-and-avoid.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general use case for Class F airspace seems to be allowing IFR flights to operate in &quot;uncontrolled airspace&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a US pilot (and thus having no experience with Class F Airspace), it sounds like the services provided in Class F airspace are effectively the equivalent of &lt;a href=&quot;http://flighttraining.aopa.org/students/crosscountry/articles/2931.html&quot;&gt;VFR Traffic Advisories (&quot;Flight Following&quot;)&lt;/a&gt;: Controllers can give you advisories and make &lt;em&gt;suggestions&lt;/em&gt;, but all responsibility is ultimately still on the pilot's shoulders, and you can politely tell the controller to get stuffed if you don't like their suggestions (without needing to declare an emergency to vest yourself with that authority).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US we already have the Flight Following system and culture set up for VFR folks (and generally speaking it's available nationwide, irrespective of airspace class, as long as the controller can get you on radar and isn't overworked). We also have a pretty robust Class E airspace nationwide.&lt;br&gt;&#xA;Because of this the FAA probably sees no need to designate specific &quot;Class F&quot; regions where IFR flights can get the equivalent of &quot;Flight Following&quot;: If you're VFR you can usually get flight following if you want it, and if you're IFR you should have no trouble staying in controlled airspace (Class A, B, C, D, or E) for your entire route of flight.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-05-01T15:55:16.203" LastActivityDate="2014-05-01T15:55:16.203" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="408" PostTypeId="2" ParentId="121" CreationDate="2013-12-26T07:37:25.683" Score="2" Body="&lt;p&gt;In the United States moored balloons (or kites) are governed under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.15&amp;amp;idno=14&quot; rel=&quot;nofollow&quot;&gt;Part 101 of the FARs&lt;/a&gt; (a much neglected and &lt;em&gt;very short&lt;/em&gt; corner of the regulations that also covers amateur rocketry and &quot;unmanned free balloons&quot; -- looking at your profile it's probably a section you'd find very interesting!). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this particular case you're probably looking for &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.15&amp;amp;idno=14#14:2.0.1.3.15.2&quot; rel=&quot;nofollow&quot;&gt;Subpart B - Moored Balloons and Kites&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FAA is mum on the specific engineering requirements of mooring systems - I expect they anticipate you will work with structural and mechanical engineers to design a tethering system that can safely hold the loads your moored object will place on it (or just tie it to the biggest, most structurally secure thing you can find, with a nice heavy rope and a proper knot).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few things they &lt;strong&gt;&lt;em&gt;ARE&lt;/em&gt;&lt;/strong&gt; pretty specific about though.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some operating limitations (altitude, size, location, visibility).&lt;/li&gt;&#xA;&lt;li&gt;The fact that you have to &lt;em&gt;tell them about it in advance&lt;/em&gt;&lt;br&gt;&#xA;(At least if it's more than 150 feet AGL, per &lt;code&gt;14CFR101.15&lt;/code&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Lighting and marking requirements for the tether(s)&lt;br&gt;&#xA;(&lt;code&gt;14CFR101.17&lt;/code&gt;, which basically says the mooring line must have pennants (daytime) and/or lights (nighttime) to ensure visibility)&lt;/li&gt;&#xA;&lt;li&gt;What happens to &lt;em&gt;Balloons&lt;/em&gt; if the tether breaks&lt;br&gt;&#xA;(&lt;code&gt;14CFR101.19&lt;/code&gt;, which basically says if the balloon breaks free of its moorings you need a &quot;rapid deflation device&quot; that gets it down in a hurry so it's not just wandering around up there).  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Interestingly they don't seem to care so much if a kite escapes its moorings.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-26T07:37:25.683" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="409" PostTypeId="2" ParentId="69" CreationDate="2013-12-26T08:02:01.383" Score="3" Body="&lt;p&gt;I'm not sure about for &quot;general maintenance&quot;, but the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook/media/FAA-8083-30_Ch08.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AMT Handbook&lt;/a&gt; chapter on inspections has some language that piqued my interest while I was trying to sniff out an answer.&lt;br&gt;&#xA;It says that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The appropriate checklist or checklists must be utilized to ensure that no items will be forgotten or overlooked during the inspection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA feels so strongly about this they even go on to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Always use a checklist when performing an inspection. The checklist may be of your own design, one provided by the manufacturer of the equipment being inspected, or one obtained from some other source.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Task cards are &lt;em&gt;basically&lt;/em&gt; a checklist (or I guess more accurately a &quot;check book&quot; - you go through and reference/fill out each card as you perform the task indicated, and the FAA wants mechanics to &lt;em&gt;use checklists&lt;/em&gt; (at least on inspections, and with the standard implied &lt;em&gt;OR ELSE&lt;/em&gt; hanging out there), so I'd imagine they're still in use in some form (though the paper / PDF product may have been replaced by something fancy and electronic).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine there are some pretty slick electronic checklist/task card systems out there by now (&lt;a href=&quot;http://avprosoftware.com/#&amp;amp;panel1-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;AvPro Software seems to offer one that I stumbled on with a quick Google search&lt;/a&gt;, no comments on quality), but I'm just the dumb slob what flies these things and I don't know much about the maintenance end - just enough to know I know enough to be dangerous if left alone with a screwdriver :-)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="11215" LastEditDate="2019-09-13T17:45:23.803" LastActivityDate="2019-09-13T17:45:23.803" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="410" PostTypeId="2" ParentId="304" CreationDate="2013-12-26T08:45:00.317" Score="7" Body="&lt;p&gt;First, if you haven't already &lt;a href=&quot;http://www.aopa.org/letsgoflying/ready/choose/howto.html&quot;&gt;go check out AOPA's Let's Go Flying site - specifically their page on how to pick a flight school/instructor&lt;/a&gt;. Some of the advice I'm going to give you is pretty much ripped right from them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For my two cents, if you're going for a career move (even a part-time side job type career), you want to optimize your training path - you do not want to be like me where you're doing this whole aviation thing &quot;just for kicks&quot; and can be be a perpetual student pilot taking as long as you want to get each rating!  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking this means you want to follow the &quot;traditional&quot; path of certificates and ratings in your chosen aircraft category and class. For Airplanes that would be Private Pilot, Instrument Rating, Commercial Pilot, and CFI.&lt;br&gt;&#xA;You &lt;em&gt;probably&lt;/em&gt; don't want to &quot;detour&quot; to ratings like Sport Pilot (unless you want to become a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a648b8f829748f1156770f7ecf441144&amp;amp;node=14:2.0.1.1.2.11&amp;amp;rgn=div6#14:2.0.1.1.2.11.1.2&quot;&gt;sport pilot instructor&lt;/a&gt; and don't intend to ever become a &quot;regular&quot; CFI, in which case this path lets you skip the instrument and commercial ratings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The private-&gt;Instrument-&gt;Commercial-&gt;CFI path is &quot;typical&quot; in my experience, and it generally seems to make sense because the skills you use in each phase naturally build on each other and will help you with the more difficult tasks the next rating will demand.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's probably also worth spending a little time with the Part 61 requirements for each certificate and rating you intend to pick up and planning ahead -- for example, if you can economize by making sure your instrument rating cross-country flight time requirements also satisfy some or all of the requirements for the Commercial rating you can avoid having to do &lt;em&gt;basically&lt;/em&gt; the same flying twice.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as where you do your training, a lot of that depends on your personal situation (funding, schedule and personality).  The general rule here is &quot;the more you fly the faster the training goes&quot;.  I was a weekend warrior for most of my private training, and between weather delays and extended gaps between lessons it took me a LONG time to get that first ticket - the instrument rating may end up taking just as long!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're a good student, can take a substantial block of vacation, and have the money to throw at your training an accelerated/immersive program is often the most cost-effective and shortest route to a given certificate or rating: You are effectively becoming a full-time flight student, flying and studying every day, and when you eat, breathe, and sleep aviation you generally pick things up a lot quicker.&lt;br&gt;&#xA;As an added advantage these are often Part 141 programs, which reduces the hour requirements for the certificates and ratings (but even if the training is conducted under Part 61 you're still at an advantage because of the immersive nature of the program).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If becoming a full-time student is not an option for you a structured Part 141 program may still be: Some Part 141 schools have &quot;weekend warrior&quot; programs that follow the same syllabus, and have the same benefit of reducing the hour requirements. The drawback is they're not as &quot;immersive&quot;, so information may not sink in as quickly and skills will probably take longer to develop - you'll take longer (and probably spend more money) as a weekend student than you would as a full-time student.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last option is &quot;regular&quot; Part 61 training, which is what most of the folks I know with day jobs they can't escape from do. This is certainly the most flexible option as you're basically training on your own schedule and program. Good instructors will almost universally still be working from some kind of syllabus to keep your training on-track and moving forward, but there's more freedom to jump around and change up the order of lessons, which is nice if you're getting stuck, or bored, or need to really work on a specific maneuver/concept for a while.&lt;br&gt;&#xA;The downside is the same as I already mentioned for &quot;weekend warrior&quot; 141 training: the time between lessons really puts a hurting on your mechanical skill development and knowledge retention, and you'll probably wind up taking longer to finish your training.&lt;br&gt;&#xA;There is however no reason you couldn't finish up a Part 61 training program right around the bare minimums for each certificate/rating, assuming you fly frequently and don't hit too many personal stumbling blocks along the way.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-26T08:45:00.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="411" PostTypeId="1" AcceptedAnswerId="413" CreationDate="2013-12-26T08:55:53.893" Score="15" ViewCount="4003" Body="&lt;p&gt;When you're circling, it has been said that you are required to keep view of the runway at all times below the MDA. However, sometimes this can be impossible due to issues with visibility, such as being banked to turn around for final, or because a flock of birds are circling between the airport and your aircraft. Are you required to execute the missed approach if this occurs or not?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="39" LastEditDate="2014-01-13T21:01:24.637" LastActivityDate="2014-03-15T03:56:37.010" Title="Are you required to have constant view of the runway when circling?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;approach&gt;&lt;circling-approach&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="412" PostTypeId="2" ParentId="362" CreationDate="2013-12-26T09:03:53.583" Score="5" Body="&lt;p&gt;I can't speak directly to the ICON A5 as I neither own nor fly one, but for every aircraft I'm familiar with the manufacturer's &quot;book numbers&quot; are generous theoretical values - for example, they typically assume flying perfectly straight-and-level in a no-wind condition, and getting the best possible fuel economy performance from the powerplant.&lt;br&gt;&#xA;The Icon folks are openly honest about this on their specs page: &lt;a href=&quot;http://www.iconaircraft.com/a5-model.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;code&gt;Performance specifications are estimates only.&lt;/code&gt;&lt;/a&gt;, and range is certainly &quot;Performance&quot; in my book.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Personally I have no doubt that the A5 could manage 300NM under the conditions for which its designers did the math to arrive at that number - it's a slick little plane with a fuel-sipping engine - but they may have done a &quot;to empty tanks&quot; calculation (leaving you to account for the &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGFAR.NSF/0/8333a51da144cf9e852566cf00618289!OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;VFR fuel reserves you're legally required to have&lt;/a&gt;), and in the real world the 15-knot headwind you run into will &lt;em&gt;substantially&lt;/em&gt; reduce your range (or, conversely, you can fly in the other direction and increase it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with all aircraft your mileage will, quite literally, vary depending on the day and direction of flight.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-26T09:03:53.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="413" PostTypeId="2" ParentId="411" CreationDate="2013-12-26T11:28:35.260" Score="14" Body="&lt;p&gt;A &quot;circle-to-land&quot; maneuver is &lt;em&gt;basically&lt;/em&gt; a low-altitude traffic pattern - albeit one that you arrived at by being guided in on some instrument approach. The magic that makes this low (and possibly abbreviated) pattern possible is that the runway ends at airports with circling approaches have protected (obstacle free) airspace around them, which looks something like this:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/kQeYS.jpg&quot; alt=&quot;Circling Approach Area&quot;&gt;&lt;br&gt;&#xA;(A more detailed explanation of the size of the circling approach area can be found &lt;a href=&quot;https://aviation.stackexchange.com/questions/973/when-conducting-a-circling-approach-how-close-do-you-have-to-stay-to-the-airpor&quot;&gt;on this question&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it's basically a traffic pattern my understanding is you treat it as such, and that as long as you stay in visual contact with the airport and within the protected airspace (by visually judging your distance from the field, and knowing your altitude) you're unlikely to hit anything, and you can do all your usual pattern maneuvering as long as you can ***visually* be sure you're within the pretty blue part of the image above (your GPS cant help you here).  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To see what this means for an example approach with some turns, consider my liberally-stolen and slightly-marked-up diagram below.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/U29gu.gif&quot; alt=&quot;Circling Approach Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you lose contact with your intended runway end for a few seconds because of the turn/bank required at point &quot;A&quot; that's OK: as long as you can still maintain visual contact with the airport/runway environment when you roll out (say by looking out the back window), and as long as you can remain clear of clouds, and can maintain visual clearance from any potential obstacles you may continue the approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're flying out and on the leg from &quot;A&quot; to &quot;B&quot; and all of a sudden you look back out the window and the airport is gone in the haze and clouds, you need to go missed: You've lost the airport/runway environment, and can no longer judge your distance to stay in the &quot;safe&quot; airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly if you're in a high-wing aircraft and your turns at &quot;B&quot; and &quot;C&quot; briefly obscure the airport while you're turning you can still continue the approach - if you've any doubt where the airport is just pick up the wing like you would in a VFR pattern (and if the airport isn't there like it's supposed to be go missed!)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding your bird scenario, that's an interesting one that I don't think is covered in any diagrams, but if a flock of birds causes you to maneuver in such a way that you lose contact with the airport (and you can't just pick up a wing and have it be right where you expected it to be) you're obviously going to have to abandon the approach and go missed. It's the equivalent of the airport disappearing in the haze on that A-to-B leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Honestly though, if a flock of birds shows up and hangs out in a way that requires you to start maneuvering around them while you're trying to shoot a circling approach in real IFR you may want to just go missed anyway (given the odds this probably won't cost you too many approaches). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a real world situation with poor visibility, possibly precipitation, and likely a cloud ceiling really close to your altitude, do you &lt;em&gt;really&lt;/em&gt; want to try to be maneuvering down low to avoid some stupid bird that couldn't even be bothered to call the tower?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't you feel much better pointing the aircraft in a generally &quot;upward&quot; direction and following the nice friendly needle again for a little while?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm just starting my IFR training, but I think I'd feel better with that option :-)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-01-13T19:23:31.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="414" PostTypeId="2" ParentId="411" CreationDate="2013-12-26T15:48:21.817" Score="9" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=f95b6f9372211ab172769488bc322b2e&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.2.6.42&amp;amp;idno=14&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.175(e)&lt;/a&gt; you must go missed...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Whenever an identifiable part of the airport is not distinctly visible&#xA;  to the pilot during a circling maneuver &lt;strong&gt;at or above MDA&lt;/strong&gt;, unless the&#xA;  inability to see an identifiable part of the airport results only from&#xA;  a normal bank of the aircraft during the circling approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I added the emphasis about the MDA, because 91.175(c) says that &lt;strong&gt;below&lt;/strong&gt; the MDA you're required to have the runway environment in sight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This FAA &lt;a href=&quot;http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=17273&quot; rel=&quot;nofollow&quot;&gt;paper&lt;/a&gt; on approaches to MDA/DH has more information and also states that the airport must be in sight:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You must have visual contact with the airport before attempting a&#xA;  circle-to-land maneuver, and you must maintain visual contact with the&#xA;  airport at all times while circling to land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AIM 5-4-21 &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;nofollow&quot;&gt;explains&lt;/a&gt; how to get established on the missed approach:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To become established on the prescribed missed approach course, the pilot should make an initial climbing turn toward the landing runway and continue the turn until established on the missed approach course&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-13T21:35:53.080" LastActivityDate="2014-01-13T21:35:53.080" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="415" PostTypeId="2" ParentId="372" CreationDate="2013-12-26T17:18:24.560" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/2a2b29ae7f0732e886257384006cb117!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;AIM 5-3-3.&lt;/a&gt; Additional Reports&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. The following reports should be made to ATC or FSS facilities&#xA;  without a specific ATC request:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. At all times.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) &lt;strong&gt;When vacating&lt;/strong&gt; any previously assigned altitude or flight level for&#xA;  a newly assigned altitude or flight level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Emphasis mine.  The phrase 'when vacating' is pretty unambiguous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edited answer to better respond to your comment. Previous answer below.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;Strike&gt;The AIM explains the purpose of readbacks in &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0404.html&quot; rel=&quot;nofollow&quot;&gt;4-4-7b&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ATC Clearance/Instruction Readback.&#xA;  Pilots of airborne aircraft should read back those parts of ATC clearances and instructions containing altitude assignments, vectors, or runway assignments as a means of &lt;strong&gt;mutual verification&lt;/strong&gt;. The read back of the “numbers&quot; &lt;strong&gt;serves as a double check&lt;/strong&gt; between pilots and controllers and reduces the kinds of communications errors that occur when a number is either “misheard&quot; or is incorrect.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although this is stretching, I find it easier to believe that a readback does not qualify and you should call again when you actually start down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, the AIM references &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/2a2b29ae7f0732e886257384006cb117!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;FAR 91.183&lt;/a&gt;, which says that the pilot of an aircraft operating under IFR must report as soon as possible&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Any other information relating to the safety of flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you figure altitude changes qualify as safety of flight information, it's probably not a bad idea to make a second radio call.&lt;/strike&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2013-12-27T05:44:43.530" LastActivityDate="2013-12-27T05:44:43.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="416" PostTypeId="2" ParentId="406" CreationDate="2013-12-26T17:32:37.100" Score="3" Body="&lt;p&gt;In Canada anyway according to the CARS (Canadian Aviation Regulations) Class F airspace is &quot;airspace of defined dimensions within which activities must be confined because of their nature, and within which limitations may be imposed upon aircraft operations that are not a part of those activities.&quot; Basically it's airspace dedicated to a certain activity and you better make damn sure you're not going to be getting in the way of that activity before you enter. &lt;/p&gt;&#xA;" OwnerUserId="205" LastActivityDate="2013-12-26T17:32:37.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="417" PostTypeId="2" ParentId="311" CreationDate="2013-12-26T17:38:48.907" Score="9" Body="&lt;p&gt;Here's my simplification, it's not the full story, but it covers the essentials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift:&#xA;When you are in free space, the high pressure below your wing dissipates into the surrounding air. When you're in ground effect, the high pressure below the wing encounters an incompressible solid, and therefore cannot dissipate as quick, causing higher pressure below the wing, and therefore more lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag:&#xA;When you're in free space, the wake (turbulent, low pressure) behind your aircraft dissipates unimpeded until it becomes uniform with the surrounding atmosphere. When you're in ground effect, the air near the ground absorbs this dissipation  quicker because it has to shear against the ground (more friction that air in free space). Additionally, wing-tip vortices encounter the ground and dissipate much quicker than in free space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect the reason GE is tied to wing length is because the longer your wing is, the stronger your wing tip vortices, and the further air has to travel laterally to exit the high pressure zone under the wing.&lt;/p&gt;&#xA;" OwnerUserId="206" LastEditorUserId="206" LastEditDate="2014-01-02T16:58:04.413" LastActivityDate="2014-01-02T16:58:04.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="418" PostTypeId="2" ParentId="406" CreationDate="2013-12-26T18:10:33.647" Score="15" Body="&lt;p&gt;Class F airspace is often used in the UK as a kind of &quot;GA airway.&quot; It designates preferred paths with a advisory ATC service that GA traffic can use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, there is a class F route defined between the north west of England and the Isle of Man. Having a preferred route and an ATC service makes sense for that route as its an expanse of open water. It simplifies search and rescue operations. &lt;/p&gt;&#xA;" OwnerUserId="210" LastActivityDate="2013-12-26T18:10:33.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="419" PostTypeId="2" ParentId="51" CreationDate="2013-12-26T19:06:17.330" Score="7" Body="&lt;p&gt;Since the question seems about aircraft theory, I'll answer with theory. The short answer is that anything can, and will fly given enough time and effort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the biggest limitations for making a conventional configuration rotary aircraft fly at supersonic speeds is materials. When a rotary blade is inline with the path of travel, it has to withstand significant compression forces along its long axis from the shock. There are three solutions for a conventional configuration - bigger &amp;amp; stronger blade (heavier) new materials, or shorter blades (less lift).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't mind deviating from conventional design, then introducing a shroud around the blades will allow you to remove these forces from consideration by allowing your shroud to absorb the forces of the created shock. You could probably reduce the weight of each individual blade by bracing it against the shroud, (think - beam braced at one end vs both ends) Since the air between a shock wave and expansion waves is sub-sonic. If you're lucky, and physics doesn't hate you, then you may get expansion waves behind the shroud, so your rotor blades will be in a sub-sonic medium. By pumping air from above the shrouded rotor to the underside, you cause lower pressure on top, higher pressure on the bottom, causing a pressure gradient and generating lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is all speculation based on my limited aerodynamics knowledge. In real life physics usually hates you, and you'll get some really messed up expansion waves and shock waves along the inside of the shroud, coupled with some fugly shocks being formed by the rotor blades themselves. Since prototyping has become super expensive, and wind tunnels seem to be a dying race nowadays, this would have to be simulated with CFD, and as far as I know, CFD isn't that fast and accurate yet, which could explain why this hasn't been tried yet.&lt;/p&gt;&#xA;" OwnerUserId="206" LastEditorUserId="206" LastEditDate="2013-12-26T19:14:38.513" LastActivityDate="2013-12-26T19:14:38.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="420" PostTypeId="1" CreationDate="2013-12-26T19:36:28.343" Score="7" ViewCount="25465" Body="&lt;p&gt;By what way and with which variables could you determine a plane's maximum rate of climb per time? If I'm not mistaken, I'm looking for V&lt;sub&gt;Y&lt;/sub&gt;.&lt;/p&gt;&#xA;" OwnerUserId="212" LastEditorUserId="7532" LastEditDate="2015-09-30T20:08:25.870" LastActivityDate="2019-03-21T14:22:38.350" Title="How can I calculate maximum rate of climb?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="421" PostTypeId="2" ParentId="41" CreationDate="2013-12-26T20:29:26.440" Score="2" Body="&lt;p&gt;I have also heard that because the 757 and 767 were developed in conjunction the 757 (although a narrow body) shares much if not all of its wing design with the wide body 767. Due to the fact that most of the wake turbulence (vortices) of an aircraft in flight is due to the air's interaction with the wing, the 757 essentially using a heavy aircraft's wing (767) causes it to have an unusual amount of wake turbulence compared to its size.&lt;/p&gt;&#xA;" OwnerUserId="214" LastActivityDate="2013-12-26T20:29:26.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="422" PostTypeId="2" ParentId="420" CreationDate="2013-12-26T20:32:54.687" Score="1" Body="&lt;p&gt;You are correct that Vy will give you the max RoC. However Vy is actually only a speed, not a climb rate, and will correspond to slightly different rates of climb depending on a few factors. The ones that spring to mind are A/C weight, temperature, and density altitude. Along with power setting but that one is somewhat self explanatory. As for determining the speed, normally you would just consult your PPOH or AOM to find a performance chart that will give you the base speed and you can correct it for each of the variables listed in order to have a precise climb rate.&lt;/p&gt;&#xA;" OwnerUserId="214" LastActivityDate="2013-12-26T20:32:54.687" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="423" PostTypeId="2" ParentId="391" CreationDate="2013-12-26T21:27:46.043" Score="10" Body="&lt;p&gt;It takes three things to make combustion - heat, fuel, oxidizer. If you eliminate air, you may not have eliminated the oxidizer if the fire has access to some other oxidizer. While decompression does eliminate some heat (probably not enough), if it's an electrical, self-oxidizing, or metal fire, you're not going to put it out with decompression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oxygen-fueled small fires can be put out with a wet cloth (like a wet cotton t-shirt). If the fire is in the engine, most (if not all) commercial planes have built in extinguishers and fuel shut-off, if it's in the baggage compartment, then there's a chance that you're not going to land fast enough to avoid structural failure on or before landing, and decompression won't help because the baggage compartment is already depressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: David Richerby brought to my attention that passenger planes have pressurized cargo areas. In my research, I came across &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q2/3/&quot; rel=&quot;noreferrer&quot;&gt;this page&lt;/a&gt; on Boeing's site. Apparently, Boeing decided to solve the issue by:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Starve the fire of oxygen&lt;br&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;for &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/25.857&quot; rel=&quot;noreferrer&quot;&gt;Class E&lt;/a&gt; cargo compartments only, the pilots do depressurize the compartment.&lt;br&gt;&lt;/li&gt;&#xA;&lt;li&gt;for other types of cargo compartments, the pilots close the vents, to essentially allow for the fire to burn out all the existing oxygen, and preventing the flow of additional oxygen to the compartment.&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;Suppressant - Planes are equipped with Halon gas that suppresses fires until the plane lands.&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="206" LastEditorUserId="97" LastEditDate="2015-05-03T04:08:58.460" LastActivityDate="2015-05-03T04:08:58.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="424" PostTypeId="2" ParentId="406" CreationDate="2013-12-26T21:53:27.263" Score="6" Body="&lt;p&gt;As voretaq7 said, it's a bit of an odd duck, and I don't know how it works in the UK but in Germany F is only to allow IFR approaches/departures for uncontrolled airfields. So basically, as soon as an airfield in G has an IFR approach, they get a F airspace around them, which in turn is usually only active when there's an IFR approach in progress. As soon as it's completed, it reverts to G (depicted on the sectional as &quot;F(HX)&quot;, meaning it's not always active). So in order to determine if F or G rules apply, you need to ask FIS or AFIS (or approach, but then you're probably IFR already, so you don't need to care).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VFR &quot;flight following&quot; is not related to the airspace and is provided by FIS in E, F and G airspace, as long as radar coverage is available pretty much. In D and C it's called CVFR and is provided by approach (or &quot;Radar&quot; as they like to call it). It works the same way when shooting an approach into a G airfield in the US, you're only cleared for the approach, as soon as you enter G, it's up to you to see and avoid, as far as I know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point of having an F airspace is that the visibility requirements are different for VFR aircraft, where you have to stay a mile away/thousand feet from clouds, whereas in G they only need to stay clear of clouds. Allowing IFR approaches in G has the potential of allowing an IFR aircraft pop out of a cloud and not have even a mile or thousand feet separation from the next VFR aircraft. Note that these extra VFR requirements are specific to Germany and deviates from the ICAO definition of airspace F.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;&lt;br&gt;&#xA;Germany is in the process of discontinuing the use of airspace F for IFR approaches into uncontrolled fields, in accordance with EU regulation 923/2012 &quot;Standardised [sic] European Rules of the Air&quot;, or SERA. Once SERA is in effect, IFR approaches will be allowed within airspace G in Germany as well. Current airspace F will be replaced with airspace G and a so called &quot;Radio Mandatory Zone&quot;, or RMZ.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-04-28T16:21:42.733" LastActivityDate="2014-04-28T16:21:42.733" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="425" PostTypeId="2" ParentId="420" CreationDate="2013-12-27T01:03:46.123" Score="1" Body="&lt;p&gt;Variables will have to include air conditions (temperature, humidity, altitude starting from), engine performance data at said altitude, and the vy speed for the airplane in question.&lt;/p&gt;&#xA;" OwnerUserId="223" LastActivityDate="2013-12-27T01:03:46.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="426" PostTypeId="1" AcceptedAnswerId="432" CreationDate="2013-12-27T01:31:09.240" Score="31" ViewCount="32257" Body="&lt;p&gt;Which is the maximum speed that an airliner is limited to while taxiing?&lt;br&gt;&#xA;I know that during 90 degree turns it is 10 knots, but what about long, straight taxiways? 20 knots? 25? 30? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More broadly, where I can find this information?&lt;br&gt;&#xA;Would it be in company SOPs? Manufacturer's FCOM?&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="572" LastEditDate="2015-02-19T10:05:55.473" LastActivityDate="2020-11-08T05:50:52.237" Title="What is the maximum taxi speed and who defines it?" Tags="&lt;aircraft-limitations&gt;&lt;taxiing&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="427" PostTypeId="1" AcceptedAnswerId="591" CreationDate="2013-12-27T01:45:44.520" Score="12" ViewCount="3585" Body="&lt;p&gt;For instance, I don't remember paragraph &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=5085c2dea08cf814d1140424b6c3e695&amp;amp;n=14y2.0.1.1.2&amp;amp;r=PART&amp;amp;ty=HTML#14:2.0.1.1.2.1.1.31&quot; rel=&quot;noreferrer&quot;&gt;61.51&lt;/a&gt;(e)(iii) at all from way back when I studied it to determine when I could log PIC time.  I'm fairly certain that it has been added since then (actually, there was no sport pilot license back then so I know that it has at least been changed), but I would like to know when it was changed and what the changes were.&lt;/p&gt;&#xA;&lt;p&gt;At the bottom of the reg, it includes this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[Doc. No. 25910, 62 FR 16298, Apr. 4, 1997; Amdt. 61-103, 62 FR 40897,&#xA;July 30, 1997; Amdt. 61-104, 63 FR 20286, Apr. 23, 1998; Amdt. 61-110,&#xA;69 FR 44865, July 27, 2004; Amdt. 61-124, 74 FR 42549, Aug. 21, 2009;&#xA;Amdt. 61-128, 76 FR 54105, Aug. 31, 2011]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This tells me &lt;strong&gt;when&lt;/strong&gt; it was amended, but not &lt;strong&gt;what&lt;/strong&gt; was amended.&lt;/p&gt;&#xA;&lt;p&gt;Does the FAA make that information available?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-02-13T16:24:32.380" Title="How can I see the revision history of a particular FAR?" Tags="&lt;faa-regulations&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="428" PostTypeId="1" AcceptedAnswerId="430" CreationDate="2013-12-27T01:50:57.347" Score="35" ViewCount="11388" Body="&lt;p&gt;It's winter time and many light aircraft are sitting idle. This can be detrimental to an engine's health.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a good rule of thumb for how often a piston engine should be exercised, and for how long?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft cannot be flown, what is an acceptable alternative?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-15T22:24:16.490" LastActivityDate="2019-02-16T21:23:16.930" Title="How often should an engine be run, to stay mechanically sound?" Tags="&lt;piston-engine&gt;&lt;aircraft-maintenance&gt;&lt;aircraft-ownership&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="429" PostTypeId="2" ParentId="145" CreationDate="2013-12-27T02:04:01.787" Score="2" Body="&lt;p&gt;Well, I have two answers for you - one personal, and one practical:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Personally&lt;/em&gt;&lt;/strong&gt;, as a pilot (and very occasional airline passenger) I think anyone operating a drone &lt;em&gt;should&lt;/em&gt; be required to get a pilot's license of some kind. Maybe I'm just grumpy, but I spent a lot of time cramming the skills and knowledge into my brain that are required to safely operate in the US National Airspace System. It can get pretty complicated and crowded up there, and I think we need the operators of unmanned aircraft to have a thorough understanding of that.&lt;br&gt;&#xA;The last thing anyone wants is a UAV smacking into a plane because it wandered somewhere it shouldn't be &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;PRACTICALLY&lt;/em&gt;&lt;/strong&gt; though, it remains to be seen what regulations the FAA will impose for unmanned civil aircraft - they may require a pilot's certificate (speculating: In the category and class equivalent to the Unmanned Aerial Vehicle you'll be operating), or they may require a &quot;remote operator's certificate&quot; of some kind (perhaps with special emphasis on remote-operation-specific issues like command uplink delay), or they may not impose a requirement at all and treat them like model aircraft until the first accident involving one of these things causes a public outcry.&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/231/64&quot;&gt;Like egid said&lt;/a&gt;, until the FAA issues a NPRM telling us what they're thinking of doing here we really won't know - your guesses are as good as ours right now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;em&gt;would&lt;/em&gt; suggest at least an Private Pilot Ground School course while you're gearing up though -- and I would suggest it even if the FAA decides no license is requried for being a UAV operator. The airspace, chart reading, flight planning, and ATC portions of the course are something you'll probably want to be familiar with (and are broadly applicable across all kinds of aviation), and a good ground school course usually isn't that expensive.&lt;br&gt;&#xA;(As to whether you take the knowledge test at the end of the course, that's up to you -- the results are good for 2 years in case you decide to pursue a pilot certificate, but the test you have to take as a UAV operator may wind up being different from the one you'd have to take as a private pilot, or may not exist at all, so you might just be setting yourself up for having to take two tests. Again, at this stage your guess would be as good as mine here.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2013-12-27T02:04:01.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="430" PostTypeId="2" ParentId="428" CreationDate="2013-12-27T02:53:11.033" Score="33" Body="&lt;p&gt;All your plane's systems are happier when you're flying, including the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, you'd fly often in order to keep your engine happy (distributing clean oil throughout the system to protect against corrosion and heating it enough to drive off water from the crankcase).&lt;br&gt;&#xA;As a rule of thumb &lt;a href=&quot;http://www.blackstone-labs.com/Newsletters/Aircraft/July-1-2013.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Blackstone Labs (the oil analysis folks) consider piston engines &quot;inactive&quot; if they've had less than about 5 hours of flight time per month&lt;/a&gt;. Their threshold &lt;em&gt;used to be&lt;/em&gt; 10 hours, so I personally try to fly at least 10 hours a month much when practical, but 5 at a minimum.&lt;br&gt;&#xA;Blackstone has a LOT of data on aircraft engine wear patterns accumulated, and I generally trust their insight in this regard (after all they're not trying to sell me an engine, just asking me to pay them to play with my used oil).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When weather or other factors mean you can't fly enough to keep your engine &quot;active&quot; you can preserve it in accordance with the manufacturer's instructions, but let's be honest, most of us aren't going to &quot;pickle&quot; our engines for the winter. It's a LOT of work, and it means you &lt;em&gt;can't go fly&lt;/em&gt; on those nice winter days we sometimes get.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In situations like this, it may be beneficial to ground-run your engine (say at least on a monthly basis) just to keep things lubricated and happy. Ground runs at a little below runup power or a fast idle are usually the order of the day here. Taxiing around is also probably a good idea, if practical, to keep your wheel bearings and related components moving -- maybe take your plane down to the runup pad and back.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;When doing the ground run you want to observe a few guidelines to make sure what you're doing is actually &lt;em&gt;beneficial&lt;/em&gt; to the engine:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Make sure you've got clean oil in the plane!&lt;/strong&gt;&lt;br&gt;&#xA;Any time you think the plane is going to be inactive you want to have good, clean oil in the engine (and you want to have done a thorough ground run or flight to spread that clean oil everywhere). This gives you optimal protection against corrosion.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Treat it like a flight.&lt;/strong&gt;&lt;br&gt;&#xA;Preflight the plane like you're taking it up, even if you're not.  You may not be flying much because of the weather, so there's a real chance your plane's systems will be in less-than-excellent shape. That thorough walk-around may catch a potentially expensive problem before it becomes a real issue.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/347/when-is-pre-heating-a-piston-engine-important-and-how-do-i-do-the-pre-heat-righ&quot;&gt;&lt;strong&gt;Preheat if necessary.&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;Hand-in-hand with treating it like a real flight, you want to make sure you're not abusing your engine in the name of protecting it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Get the engine oil to normal operating temperature.&lt;/strong&gt;&lt;br&gt;&#xA;Part of the point of the ground run is to drive off water that has condensed in your oil -- oil is good for metal parts, and water is bad for them.&lt;br&gt;&#xA;If you don't get the engine oil up to normal middle-of-the-green-arc temperatures and keep it there for a good while (20-30 minutes at least) you may not be driving out the water, which can lead to a very unhappy engine.&lt;br&gt;&#xA;&lt;strong&gt;&lt;em&gt;If you don't get the oil up to operating temperature long enough you may wind up doing more harm than good!&lt;/em&gt;&lt;/strong&gt; Combustion blow-by leaking around the piston rings contains water (and a bunch of other corrosive things your engine doesn't like), and really short ground runs that don't bring the engine to temperature are mainly just causing wear from the startup and dumping these nasty things into your oil. Your engine is not going to like that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Run long enough to recharge your battery.&lt;/strong&gt;&lt;br&gt;&#xA;Watch your ammeter/load meter after startup, and make sure that your battery has been replenished before you shut down.&lt;br&gt;&#xA;This means running your engine at a high enough RPM that the charging system can charge the battery (a fast idle is usually fine), and long enough that the battery can be charged (which isn't a problem, because if you were paying attention to #4 you've noticed we'll be running the engine a good while anyway).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Monitor your cylinder head temperatures.&lt;/strong&gt;&lt;br&gt;&#xA;If equipped with CHT probes, make sure you're not exceeding the CHT limits for your engine during the ground runs.  This goes hand in hand with #7 below.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Lean your mixture to avoid fouling your plugs.&lt;/strong&gt;&lt;br&gt;&#xA;You should be using less than 65% of your engine's max rated power for these ground runs -- in fact, you should &lt;em&gt;probably&lt;/em&gt; be somewhere around 50-60%.  Rather than running full rich, pull back on the red knob and let the engine burn cleaner (but keep an eye out for the warning signs of detonation/preignition).&lt;br&gt;&#xA;You probably only want to do this if you've got Cylinder Head Temperature readouts you trust -- when in doubt you can always run full rich (for the added cylinder cooling) and just clean your plugs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Depending on the outside air temperature your ground run may last anywhere from 30 minutes to 90 minutes (I've not personally had one last longer than that, though it's theoretically possible I suppose) -- it all depends on how long #4 and #5 above take.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A final thought: I use ASL CamGuard in my oil. It goes in with every oil change.  &lt;a href=&quot;http://www.aircraftspruce.com/catalog/pdf/ASL_NEWSLETTER_vol_1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mike Busch (a smarter guy than me) swears by it&lt;/a&gt;, and there seems to be ample real-world-anecdotal evidence as well as a good amount of actual materials testing research that indicates it's a pretty decent corrosion inhibitor.&lt;br&gt;&#xA;I've not had my plane/engine long enough to know if this treatment is effective or not, but it certainly doesn't seem to be &lt;em&gt;hurting&lt;/em&gt; anything, and while it's a little expensive it's not &quot;liquid gold&quot; prices, so it strikes me as cheap enough insurance that you may as well dump it in the sump. This is especially true when you weigh it against the price of a bottom-end overhaul because you got pitted cam lobes or lifters...&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="37321" LastEditDate="2019-02-16T21:23:16.930" LastActivityDate="2019-02-16T21:23:16.930" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="431" PostTypeId="2" ParentId="427" CreationDate="2013-12-27T03:03:30.270" Score="4" Body="&lt;p&gt;You can find this information with a bit of digging.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hit up the GPO (Government Printing Office) &lt;a href=&quot;http://www.gpo.gov/fdsys/browse/collectionCfrFR.action?collectionCode=CFRPARTS&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Choose the date range you want to look up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then choose the Title of the CFR you want (Aviation stuff is Title 14 CFR), and drill down until you find the Part you want, and it will give you some meta data about the change, and then the actual text of the change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There might be an easier way, but, it is the federal government, so maybe not. :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your specific question, &lt;a href=&quot;http://www.gpo.gov/fdsys/search/pagedetails.action?browsePath=&amp;amp;granuleId=2011-26229&amp;amp;packageId=FR-2011-10-12&amp;amp;fromBrowse=true&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; is the link. (Click on the &quot;Text&quot; link for full details)&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="97" LastEditDate="2015-05-03T04:09:45.813" LastActivityDate="2015-05-03T04:09:45.813" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="432" PostTypeId="2" ParentId="426" CreationDate="2013-12-27T03:25:24.833" Score="24" Body="&lt;p&gt;A &amp;quot;Safety Alert for Operators&amp;quot; (SAFO 09004) from 2/11/09 says &amp;quot;Slow the aircraft to a fast walking speed on the centerline of the landing runway prior to attempting to exit the runway. Taxi at a fast walking speed until parked at the ramp or until aligned with the centerline of the runway for takeoff.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Which, of course, isn't a regulation, in this example is specifically talking about winter conditions.&lt;/p&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2009/SAFO09004.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2009/SAFO09004.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Riverside County in Southern California has an ordinance (regulation) that states:&#xA;Section 12.08.100 Taxi speed.&#xA;No person shall taxi any aircraft on the airport unless there will be no danger of collision&#xA;with any person or object. &lt;strong&gt;All aircraft shall be taxied at a safe and reasonable speed&#xA;commensurate with safe operation&lt;/strong&gt; in relation to existing conditions and with due regard for&#xA;other aircraft, persons and property. (Ord. 5661 § 1, 1988; prior code § 5.11 (part))&#xA;Source: &lt;a href=&quot;http://www.riversideca.gov/municode/pdf/12/12-08.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.riversideca.gov/municode/pdf/12/12-08.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;So whatever a &amp;quot;safe and reasonable speed&amp;quot; is.  I've heard it called a &amp;quot;brisk walking pace.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;I had an airline pilot as a ground school instructor once, and she said that ground control was giving them a hassle one day, so everyone decided to taxi at a &amp;quot;brisk walking pace&amp;quot; around LAX.  Got ground whipped into shape real quick!&lt;/p&gt;&#xA;&lt;p&gt;The FAA's website, under &amp;quot;Best Practices&amp;quot; says to &amp;quot;Maintain an appropriate taxi speed.&amp;quot;&#xA;&lt;a href=&quot;http://www.faa.gov/airports/runway_safety/pilots/best_practices/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/airports/runway_safety/pilots/best_practices/&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Since it's not clearly defined by the FAA, I assume that most airlines limit taxi speeds via their SOPs, also due to the variety of equipment, it might be unfeasible for the FAA to mandate a specific speed.&lt;/p&gt;&#xA;&lt;p&gt;Roughly:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max 30 kts: straight line with no close obstacles (for example: back-tracking on the runway)&lt;/li&gt;&#xA;&lt;li&gt;Max 20 kts: straight line with obstacles (for example: on the taxiway, or close to other aircraft/stands/ground vehicles)&lt;/li&gt;&#xA;&lt;li&gt;Max 10 kts: turns and entry onto ramp area&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="132" LastEditorUserId="132" LastEditDate="2020-11-08T05:50:52.237" LastActivityDate="2020-11-08T05:50:52.237" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="433" PostTypeId="1" AcceptedAnswerId="437" CreationDate="2013-12-27T04:57:53.763" Score="24" ViewCount="20077" Body="&lt;p&gt;If I own a helicopter and am appropriately rated, can I land the helicopter anywhere that isn't private property, and is a safe place to land (clear of obstructions, appropriate surface, etc.)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is specifically about the regulatory requirements to land a helicopter off-airport in the United States.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="69" LastEditDate="2014-01-18T17:52:33.963" LastActivityDate="2014-01-18T17:52:33.963" Title="Can I land a helicopter anywhere?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="434" PostTypeId="1" AcceptedAnswerId="435" CreationDate="2013-12-27T05:04:21.273" Score="13" ViewCount="1477" Body="&lt;p&gt;In flight training, you're always told not to cross-control, (for example, rolling right aileron, and stepping on the left rudder), but it seems to me that is exactly what a slip is doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it that a slip is intentional, and a cross-controlled situation is typically unintentional?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="65" LastEditDate="2015-03-20T19:54:50.387" LastActivityDate="2018-05-26T15:29:00.287" Title="Is a slip an intentional consequence of a cross-control?" Tags="&lt;aerodynamics&gt;&lt;maneuver&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="435" PostTypeId="2" ParentId="434" CreationDate="2013-12-27T06:11:31.427" Score="14" Body="&lt;p&gt;You are right: A slip is a cross-controlled (and uncoordinated) situation. It's exactly what your instructor was teaching you to avoid during your early lessons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as nomenclature goes: all slips are cross-controlled maneuvers, but not all cross-controlled maneuvers are slips: On climb-out in most piston singles you will be stomping on the right rudder to offset the plane's left-turning tendencies, and you will probably notice that you're rolling in a tiny bit of left aileron (which offsets the banking tendency introduced by the rudder) - your controls may be very slightly crossed, but the result is coordinated flight (a centered ball).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The real difference here between an &quot;unintentionally cross-controlled situation&quot; and an &quot;intentional slip&quot; is the intentional bit: When you are knowingly slipping the aircraft - for example to bleed off altitude on a high final without increasing your airspeed - you're aware that you're flying in an uncoordinated and aerodynamically unstable condition. You're aware of the risks, and are hopefully monitoring the aircraft carefully to avoid a stall/spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a little more insight, faaflighttest.us &lt;a href=&quot;http://faaflighttest.us/Cross-Controlled.pdf&quot;&gt;has a reprint/copy of an Aviation Safety article from April 2006&lt;/a&gt; which is worth a read, and possibly an hour in the air practicing some of what they discuss with your instructor so you can get the &quot;feel&quot;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-27T06:11:31.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="436" PostTypeId="2" ParentId="6" CreationDate="2013-12-27T07:59:53.163" Score="4" Body="&lt;p&gt;You can also familiarize yourself with helicopter routes for the airspace you're flying in. I fairly frequently go into the BOS class B and almost always use a helicopter route in and out, which helps ATC know exactly what you're referring to.&lt;/p&gt;&#xA;" OwnerUserId="222" LastActivityDate="2013-12-27T07:59:53.163" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="437" PostTypeId="2" ParentId="433" CreationDate="2013-12-27T08:06:18.450" Score="9" Body="&lt;p&gt;Per &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/b4a0cab3e513bb58852566c70067018f/91693c93525de33e862576c100763e31!OpenDocument&quot;&gt;§91.119 of the FARs&lt;/a&gt;, yes. That said, you can't just find an open field-there may be local/state regulations regarding helicopter operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 91.119:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) A helicopter may be operated at less than the minimums&#xA;  prescribed in paragraph (b) or (c) of this section, provided each&#xA;  person operating the helicopter complies with any routes or altitudes&#xA;  specifically prescribed for helicopters by the FAA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="222" LastEditorUserId="39" LastEditDate="2013-12-27T18:20:32.230" LastActivityDate="2013-12-27T18:20:32.230" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="438" PostTypeId="2" ParentId="157" CreationDate="2013-12-27T08:09:27.150" Score="11" Body="&lt;p&gt;The license required for operating a manned free balloon would be a &quot;Lighter-than-air, Balloon&quot; license (as opposed to a &quot;regular&quot; license, which is usually thought of as being for &quot;regular&quot; Airplanes - the kind that take off and land using runways, as opposed to lakes).&lt;br&gt;&#xA;Cluster balloons are, for all regulatory purposes, just &quot;balloons&quot; - the only difference is rather than having one monolithic envelope filed with hot air like the balloons most of us are used to seeing they have a bunch of smaller envelopes, usually filled with helium.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://amsrvs.registry.faa.gov/airmeninquiry/&quot;&gt;An Airman Registry Search&lt;/a&gt; shows that there is one &quot;John Ninomiya&quot;, with a commercial pilot's license for lighter-than-air balloons, which is consistent with what I'd expect.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A lot of the requirements for a private pilot license in balloons are similar to what you need to do to get a private pilot license in an airplane - for example you still need to learn the same regulatory environment, you'll learn to read the same charts, you'll cover flight planning and weather, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The differences are that you'll be learning balloon systems rather than aircraft systems, and the experience requirements under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.5.1.5&quot;&gt;FAR 61.109&lt;/a&gt; are pretty radically different because of the fact that balloon flying is pretty radically different from flying around in an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can peruse &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14&quot;&gt;Part 61 of the FARs&lt;/a&gt; for all the specific details on training requirements for lighter-than-air balloon pilot certificates - &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.5&quot;&gt;Subpart E  (Private Pilots)&lt;/a&gt; is probably where you want to look.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-27T08:09:27.150" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="439" PostTypeId="1" AcceptedAnswerId="453" CreationDate="2013-12-27T09:28:05.630" Score="26" ViewCount="9519" Body="&lt;p&gt;How does an aircraft tailplane keep the aircraft stable, and prevent it from tipping over? Also, how does the lift generated by a tailplane compare to that generated by the wing?&lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="97" LastEditDate="2014-01-28T17:33:55.400" LastActivityDate="2019-08-19T06:17:32.053" Title="How does an aircraft tailplane work?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="440" PostTypeId="2" ParentId="439" CreationDate="2013-12-27T09:37:00.013" Score="7" Body="&lt;p&gt;A wing with a conventional aerofoil profile makes a negative contribution to longitudinal stability. This means that any disturbance (such as a gust) which raises the nose produces a nose-up pitching moment which tends to raise the nose further. With the same disturbance, the presence of a tailplane produces a restoring nose-down pitching moment, which may counteract the natural instability of the wing and make the aircraft longitudinally stable (much the same way a windvane always points into the wind). &lt;a href=&quot;https://en.wikipedia.org/wiki/Tailplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;(From the Wikipedia page on tailplanes)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tailplane does not produce any lift. You could say it produces a 'Negative Lift'. The reason many early aviators were killed is because the tailplanes produced lift in order to help the plane fly which would result in unrecoverable nose-up tailplane stall. Most modern aircraft are designed so that when the airflow decreases, the effect/momentum produced by the tail surface is decreased as to prevent the previously mentioned condition&lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="9839" LastEditDate="2019-08-19T06:17:32.053" LastActivityDate="2019-08-19T06:17:32.053" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="441" PostTypeId="2" ParentId="433" CreationDate="2013-12-27T09:39:15.697" Score="4" Body="&lt;p&gt;It all depends on the exact location. You need the Federal, State, Local, USFS, Zoning, etc... If you have a spot you'd like to land at, you need to start doing the research early and make sure you don't forget any agency or possible owner before you land. Just because the land owner says it's ok, doesn't mean you won't get into serious trouble with someone else.&lt;/p&gt;&#xA;" OwnerUserId="163" LastActivityDate="2013-12-27T09:39:15.697" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="442" PostTypeId="2" ParentId="389" CreationDate="2013-12-27T09:48:48.700" Score="0" Body="&lt;p&gt;Think about &lt;em&gt;why&lt;/em&gt; you have to choose an alternate airport. The most important thing to remember about alternates is that they will only be used when the weather is bad.  The destination airport has gone below IFR minimums, and you are now relying on your alternate airport to get safely back on the ground.  The planned flight has essentially been aborted, and a back-up plan of action is required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So even if the rules do not dictate that you should get an alternate airport, it's best to have one or more in case something goes wrong. During an emergency the last thing you want to do is get a chart and start finding an airport. &lt;/p&gt;&#xA;" OwnerUserId="163" LastActivityDate="2013-12-27T09:48:48.700" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="443" PostTypeId="1" AcceptedAnswerId="450" CreationDate="2013-12-27T11:49:34.933" Score="18" ViewCount="2237" Body="&lt;p&gt;What should a pilot of any large commercial passenger airplane do if they feel sleepy?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the maximum time per day during which  the pilot may control the airplane ?&lt;/p&gt;&#xA;" OwnerUserId="140" LastEditorUserId="12720" LastEditDate="2017-05-21T13:53:26.580" LastActivityDate="2017-05-21T13:53:26.580" Title="What should a pilot do if they feel sleepy?" Tags="&lt;safety&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="444" PostTypeId="2" ParentId="439" CreationDate="2013-12-27T12:02:27.077" Score="2" Body="&lt;p&gt;The wings(which has a aerofoil cross section ) produce lift (basically a force that acts opposite to weight)  which act at a distance from center of gravity (C.G) so the force gets transferred to C.G. as a force and moment(in clockwise direction) which lead to  pitch up movement&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To balance that moment tail are used the tail produce lift (small compared to that produced by wings) so if we transfer it to C.G. an force and moment (since it produce less lift it should be placed far from C.G)  this moment acts in anticlockwise direction thus neutralizing the moment due to wings ...Thus making the aircraft stable ...&lt;/p&gt;&#xA;" OwnerUserId="140" LastActivityDate="2013-12-27T12:02:27.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="445" PostTypeId="2" ParentId="439" CreationDate="2013-12-27T13:29:54.943" Score="1" Body="&lt;p&gt;The absolute value of the lift generated by the tailplane varies and depends on the phase in which your plane is in that moment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Takeoff (flaps extended): high drift&lt;br&gt;&#xA;  Climb (no flaps): mostly lift (not much)&lt;br&gt;&#xA;  Cruise (no flaps): drift&lt;br&gt;&#xA;  Landing (flaps extended): high drift&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Due to the fuel consumption the weight of the plane reduces while flight. This may change the position of your center of gravity and this in turn will affect the absolute value of your lift/drift. Usually |drift| increases, in other words, while flight the lift of the tailplane decreases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some words to stability:&#xA;Just think about equilibrium of moments.&lt;br&gt;&#xA;The center of gravity is near the main wing. The high lift of the main wing is very near to c.o.g., the drift of the tailplane is rather far away from it. The sum of all moments equals zero, they will balance the plane if there are gusts etc.&lt;/p&gt;&#xA;" OwnerUserId="190" LastActivityDate="2013-12-27T13:29:54.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="446" PostTypeId="1" AcceptedAnswerId="449" CreationDate="2013-12-27T15:32:39.057" Score="13" ViewCount="1501" Body="&lt;p&gt;On two of my trips (same airline, same kind of plane 777), I noticed that the airplane took very different routes (from New York to UAE).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1st Trip in 2012 (blue): Duration 11h 30m&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2nd Trip in 2013 (green): Duration 13h 00m&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that the blue line is the shorter distance, and probably also because of jet streams, it took lesser time. But why a plane would take this green route, even not considering jet streams?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I am not an important person, I could not ask the captain of the plane this question at the end of journey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;P.S.: I observed the flight paths on the entertainment system this airline has for all passengers.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CyJ4F.gif&quot; alt=&quot;Travel Path&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="572" LastEditDate="2015-02-19T16:16:48.083" LastActivityDate="2015-06-05T09:59:17.023" Title="Why are different routes flown between the the same pair of airports?" Tags="&lt;flight-planning&gt;&lt;international&gt;&lt;oceanic&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="447" PostTypeId="2" ParentId="389" CreationDate="2013-12-27T15:38:01.937" Score="2" Body="&lt;p&gt;This isn't very clear, at least based on the published information that I could find. The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0501.html&quot; rel=&quot;nofollow&quot;&gt;AIM 5-1-9&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Use of FAA Form 7233-4 is recommended for domestic IFR flights and is&#xA;  mandatory for all IFR flights that will depart U.S. domestic airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/flight_plan_filing/media/faa7233-4.pdf&quot; rel=&quot;nofollow&quot;&gt;7233-4&lt;/a&gt; is basically an ICAO flight plan form, and the AIM says this about the alternates:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Alternate and 2nd Alternate Aerodrome (Optional)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But it isn't clear - to me - if the word &quot;optional&quot; applies here to the entire line, or only to the second alternate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the AIM also says this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE- Although alternate airport information filed in an FPL will be&#xA;  accepted by air traffic computer systems, it will not be presented to&#xA;  controllers. If diversion to an alternate airport becomes necessary,&#xA;  pilots are expected to notify ATC and request an amended clearance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That could mean that both the alternate and second alternate are optional, since there would be no point in requiring information that isn't even visible to ATC. However that's a guess and could easily be wrong (the data could be useful in other ways); I couldn't find any guidance on this on ICAO's site either. And airlines probably have their own internal rules on identifying and filing alternates as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flight returning to the US would almost certainly use an ICAO flight plan, so whatever the correct interpretation of &quot;optional&quot; is here, it would apply to those flights too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, regardless of what the regulations say, filing alternates does have the significant benefit of 'forcing' you to plan and review your route more carefully.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-27T15:38:01.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="448" PostTypeId="2" ParentId="426" CreationDate="2013-12-27T15:46:28.360" Score="27" Body="&lt;p&gt;And here, a Reference from &lt;a href=&quot;http://www.737ng.co.uk/B737%20Flight%20Crew%20Training%20Manual%20-%20All.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boeing's 737 FCTM (pdf)&lt;/a&gt;. Ch2 for ground operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sadCJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="39" LastEditDate="2013-12-27T19:51:09.753" LastActivityDate="2013-12-27T19:51:09.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="449" PostTypeId="2" ParentId="446" CreationDate="2013-12-27T16:03:24.487" Score="15" Body="&lt;p&gt;Lots of reasons are possible, ranging from winds to other issues. In this case I'm willing to bet that the first flight was based on the most efficient routing to take advantage of tailwinds en route and that the second was avoiding Syrian and Turkish air space because of the political issues there earlier this year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.rhinocarhire.com/Car-Hire-News/September-2013/Flight-Delays-Incurred-Avoiding-Syrian-0163.aspx&quot;&gt;Flight Delays Incurred Avoiding Syrian Airspace&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.arabianbusiness.com/royal-jordanian-stops-flying-over-syrian-airspace-491765.html&quot;&gt;Royal Jordanian stops flying over Syrian airspace&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="241" LastEditorUserId="65" LastEditDate="2015-02-19T15:42:32.537" LastActivityDate="2015-02-19T15:42:32.537" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="450" PostTypeId="2" ParentId="443" CreationDate="2013-12-27T16:16:56.670" Score="23" Body="&lt;p&gt;If a pilot is not rested enough to safely operate the aircraft, they should not fly. If a pilot is flying and falling asleep, they should switch out with another pilot or land.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current FAA regulations for domestic flights generally limit pilots to eight hours of flight time during a 24-hour period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the Air Force, actual flight duty periods vary depending on the aircraft type and mission but we are required to get 12 hours of crew rest with the opportunity for 8 hours of uninterrupted rest prior to flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read the FAA's Fact Sheet on Pilot Flight Time, Rest, and Fatigue &lt;a href=&quot;http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=6762&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="244" LastEditorUserId="72" LastEditDate="2014-03-11T09:24:35.397" LastActivityDate="2014-03-11T09:24:35.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="451" PostTypeId="1" AcceptedAnswerId="452" CreationDate="2013-12-27T16:29:36.433" Score="5" ViewCount="494" Body="&lt;p&gt;In the USA, what training options does a student pilot aiming for their private pilot license have?&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="1696" LastEditDate="2015-02-09T18:19:00.343" LastActivityDate="2015-02-09T18:19:00.343" Title="What are the flight training options for a private pilot's license in the US?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;flight-training&gt;&lt;ppl&gt;&lt;flight-school&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="452" PostTypeId="2" ParentId="451" CreationDate="2013-12-27T16:50:15.017" Score="9" Body="&lt;p&gt;There are lots of options. Flight training is the US is usually divided into &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14&quot;&gt;part 61&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;tpl=/ecfrbrowse/Title14/14cfr141_main_02.tpl&quot;&gt;part 141&lt;/a&gt;. Part 61 is general flight instruction and any FAA approved instructor can teach you under it: many part 61 instructors are independent or work for or with FBOs at GA airports. Part 141 governs flight schools that have a standard curriculum and are much more structured; they're often associated with training commercial pilots looking for airline careers. The license you get is exactly the same whichever way you learn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are pros and cons to both approaches, &lt;a href=&quot;http://www.flyingmag.com/pilot-technique/new-pilots/flight-school-part-61-or-part-141&quot;&gt;this article&lt;/a&gt; summarizes them well but the most important general point is probably that part 61 is 'one on one' training so it can be tailored for you and fit your schedule, whereas part 141 is 'school' training and if you can't follow their schedule then it usually isn't possible anyway. For that reason, part 61 is often the only practical option for many private pilots who have jobs and families.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps your real question here is &quot;how do I find an instructor?&quot;, in which case you need to search the web, check out local FBOs and flight schools, ask for recommendations from pilots you know and so on. It's definitely worth investing some time to find the right instructor for you, because that can make a huge difference to your progress (and your costs).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2013-12-27T16:50:15.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="453" PostTypeId="2" ParentId="439" CreationDate="2013-12-27T16:51:34.523" Score="21" Body="&lt;p&gt;For conventional designs, the tail is composed of two parts: the horizontal tail and the vertical tail. They play a role in the trim and the manoeuvrability of the aircraft but at different levels. The horizontal tail is mainly used for longitudinal stability (and trim) while the vertical tails used for the lateral stability (and trim).&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;About Stability&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;It is possible to talk of stability only after having defined an equilibrium point around which the stability is studied. An aircraft is in equilibrium if the forces and moments it experiences are balanced. Using a simple model for the longitudinal analysis, it can be decomposed in three relations called the trim equations. In order to keep it simple, it will be assumed here that the angle of attack and the flight path angle are zero. (Note that the same reasoning can be achieved with non-zero values but the equations then become quite messy.)&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Longitudinal Equilibrium&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;These three equations are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L=mg$$&#xA;$$T=D$$&#xA;$$M=0$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $L$ is the total lift, $mg$ is the weight of the aircraft, $T$ is the thrust, $D$ is the drag and $M$ is the pitching moment around the centre of gravity of the aircraft. The second equation won't be studied further since it does not help to understand the role of the horizontal tail and its influence. Looking at the following picture, one can see that usually, the centre of gravity and the point where the lift applies (called the aerodynamic centre) are not the same. This means that the lift generated by the wing creates an induced moment around the centre of gravity that one should add to the already intrinsic pitching moment due to the main wing (usually a pitch down moment for conventional airfoils).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rM5V8.png&quot; alt=&quot;Longitudinal Stability&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing that, it is possible to rewrite the two equations of interest including the contributions from the main wing and from the horizontal tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$W+L_t=L_w$$&#xA;$$M_0+bL_t=aL_w$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From these equations and the figure, it appears that the horizontal tail is used to generate a lift which induces a moment helping to balance the moments equilibrium and thus prevent the aircraft to spin on itself (pitchwise).&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Drawback and Solution&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;From both the figure and the equations it turns out that the lift contribution from the tail is usually negative, meaning that more lift from the main wing is needed to keep a trimmed (or balanced) aircraft. This drawback can be overcome by the use of a canard configuration instead.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Lateral Stability&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The same can be done for the lateral equilibrium and stability but there it is the vertical tail that is used. It is symmetrical so that there is no yaw induced and if there is some side force experienced, it will create a moment in order to reduce the side-slip angle.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Comparison of Lift Created by the Tail and Main Wing&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;For a trimmed configuration, it is easy to see that the lift created by the main wing is more or less the one created by the tail plus the total weight of the aircraft, which gives an idea of the difference between the two forces.&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="97" LastEditDate="2014-04-17T02:40:14.207" LastActivityDate="2014-04-17T02:40:14.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="456" PostTypeId="2" ParentId="451" CreationDate="2013-12-27T19:53:25.750" Score="4" Body="&lt;p&gt;Practically, the biggest variance in cost is going to be the price per hour of the airplane you rent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A brand new Garmin 1000 equipped 172 might be 175 bucks an hour plus.  There may or may not be a fuel surcharge on top of that.  A 1968 Piper Warrior with basic instruments might be 100 an hour fuel included.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For basic VFR training you don't need a shiny new airplane with lots of bells and whistles, so if you're shopping for price, shop based on the price and availability of rental planes.  Instructor fees and other costs won't vary much.&lt;/p&gt;&#xA;" OwnerUserId="223" LastEditorUserId="223" LastEditDate="2013-12-27T20:00:44.303" LastActivityDate="2013-12-27T20:00:44.303" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="457" PostTypeId="5" CreationDate="2013-12-27T20:30:38.750" Score="0" Body="&lt;p&gt;Regulations mean the legally enforceable rules for operating and maintaining aircraft, training pilots etc. This usually refers to laws such as the &lt;a href=&quot;http://www.faa.gov/regulations_policies/faa_regulations/&quot; rel=&quot;nofollow&quot;&gt;Federal Aviation Regulations&lt;/a&gt; in the USA and their equivalents in other jurisdictions, although it can also include local laws that may impact aviation such as zoning, noise reduction and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regulations may also include publications like the US &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Information Manual&lt;/a&gt; which, although not made up of actual laws, is still considered regulatory in the sense that any deviation from its recommendations could be subject to review by the aviation authorities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Information about best practices, techniques, tips etc. are not regulations.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2013-12-30T21:51:05.450" LastActivityDate="2013-12-30T21:51:05.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="458" PostTypeId="4" CreationDate="2013-12-27T20:30:38.750" Score="0" Body="Questions about legal or administrative regulations that apply to flying, training, maintenance etc. This covers only what is required and enforceable by the applicable legal authorities, it does not include best practices, tips or other information." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2013-12-30T21:52:25.067" LastActivityDate="2013-12-30T21:52:25.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="459" PostTypeId="5" CreationDate="2013-12-27T20:52:34.547" Score="0" Body="&lt;p&gt;Flight training includes all forms of required or voluntary flight training for pilots and other crew. This includes training for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilots and other flight crew&lt;/li&gt;&#xA;&lt;li&gt;Cabin crew&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about flight training and testing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For questions about licensing, privileges and so on, use the tag for the appropriate regulatory authority (&lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/easa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;easa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;easa-regulations&lt;/a&gt;, etc).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-07-31T19:49:46.080" LastActivityDate="2015-07-31T19:49:46.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="460" PostTypeId="4" CreationDate="2013-12-27T20:52:34.547" Score="0" Body="Flight training includes all aspects of training and testing pilots and other crew members" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-07-31T19:49:46.080" LastActivityDate="2015-07-31T19:49:46.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="461" PostTypeId="5" CreationDate="2013-12-27T20:59:39.927" Score="0" Body="&lt;p&gt;This tag should be used for questions about flights that depart from one country and overfly or land in another. Because different countries have different regulations, standards and languages, it is not always obvious which rules and regulations are in force for international operations or what practices are usually followed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag should also be used for questions about air traffic control over oceanic regions of international airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag should not be used for activities such as maintenance or national air traffic control, which are clearly limited to one specific country.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2013-12-30T21:49:59.523" LastActivityDate="2013-12-30T21:49:59.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="462" PostTypeId="4" CreationDate="2013-12-27T20:59:39.927" Score="0" Body="This tag should be used for questions about flights that depart from one country and land in another one, i.e. it is not always obvious which jurisdictions have control over the flight." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2013-12-30T21:51:00.497" LastActivityDate="2013-12-30T21:51:00.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="463" PostTypeId="5" CreationDate="2013-12-27T21:10:44.590" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://www.icao.int&quot; rel=&quot;nofollow&quot;&gt;International Civil Aviation Organization&lt;/a&gt; is a UN body headquartered in Montreal. It plays a major role in international aviation by developing and promoting unified international standards for training, navigation, infrastructure, flight planning and other aspects of aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about ICAO itself, e.g. membership, publications, legal authority. For questions about international aviation regulations and standards defined by ICAO, use &lt;a href=&quot;/questions/tagged/icao-sarps&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;icao-sarps&amp;#39;&quot; rel=&quot;tag&quot;&gt;icao-sarps&lt;/a&gt; instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For questions about regulations in specific countries or regulations defined by other bodies such as the FAA or EASA, use the more appropriate 'local' tag, e.g. &lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/easa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;easa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;easa-regulations&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-09-09T13:37:36.757" LastActivityDate="2016-09-09T13:37:36.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="464" PostTypeId="4" CreationDate="2013-12-27T21:10:44.590" Score="0" Body="The International Civil Aviation Organization is a UN body that develops international aviation standards." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-25T23:25:56.140" LastActivityDate="2014-01-25T23:25:56.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="466" PostTypeId="1" CreationDate="2013-12-27T23:32:59.957" Score="28" ViewCount="3999" Body="&lt;p&gt;As an engineer I can explain in very technical terms exactly what makes an airplane fly, however, it isn't easily understood by non-technical people.  How can I explain it to a non-technical person, or a nine year old, in a way that isn't really incorrect but is far less technical than what we learn as pilots?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14197" LastEditDate="2017-04-26T13:42:18.240" LastActivityDate="2019-09-11T18:27:36.860" Title="How do I explain what makes an airplane fly to a non-technical person?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="467" PostTypeId="2" ParentId="389" CreationDate="2013-12-28T00:54:41.657" Score="3" Body="&lt;p&gt;I think the answer here is &quot;It depends on the rules of the countries whose airspace you will be using&quot; -- For example if I'm going in to Canada from my home base in New York I would need an alternate airport if &lt;strong&gt;&lt;em&gt;either&lt;/em&gt;&lt;/strong&gt; the US or Canadian regs required one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course &lt;a href=&quot;https://aviation.stackexchange.com/a/442/64&quot;&gt;as Lucas pointed out&lt;/a&gt; what is legal and what is prudent aren't always the same: you probably want to have an alternate airport &lt;em&gt;in mind&lt;/em&gt; for every flight (VFR or IFR), and you may want to list them on your flight plans so ATC has the information (even if it's not visible to controllers it can be used for Search &amp;amp; Rescue purposes and the like if the worst should happen).&lt;br&gt;&#xA;Similarly you probably want to have multiple realistic diversion options in mind along your whole route, just to have all your bases covered. &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2013-12-28T00:54:41.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="468" PostTypeId="2" ParentId="466" CreationDate="2013-12-28T02:47:14.690" Score="15" Body="&lt;p&gt;Here's one way to do it: airplanes work by pushing air. The wings push air down, and the airplane turns by pushing air in different ways. Engines push air to the back, pulling the plane forward. Wings work by turning the air downwards--the airflow on the top of the wing follows the curve of the wing, which points it downward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My apologies if this is too low-level--is this what you had in mind?&lt;/p&gt;&#xA;" OwnerUserId="222" LastEditorUserId="222" LastEditDate="2013-12-30T03:51:52.400" LastActivityDate="2013-12-30T03:51:52.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="469" PostTypeId="2" ParentId="69" CreationDate="2013-12-28T03:00:32.663" Score="6" Body="&lt;p&gt;I just watched &lt;a href=&quot;http://www.bbc.co.uk/programmes/b01l1w71&quot; rel=&quot;nofollow noreferrer&quot;&gt;Engineering Giants - Jumbo Jet Strip-Down&lt;/a&gt;, following a British Airways 747 on its D-Check in 2012.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least for BA, it would seem that paper task/job cards are still heavily used. Apparently there are over 12,000 individual jobs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've taken a short (7 secs) clip from the episode, showing walls full of task cards:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/CWsvUjyrHO8?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5pzSn.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:10:37.907" LastActivityDate="2015-10-01T19:10:37.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="470" PostTypeId="2" ParentId="466" CreationDate="2013-12-28T03:04:34.873" Score="45" Body="&lt;p&gt;The simplest explanation is the &quot;hand out of the window&quot; one:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hold your hand out of the window while in a moving car and hold your hand at an angle. It gets pushed upwards. Your hand represents the wing of an airplane. The plane's engine simply makes sure the &quot;hand&quot; keeps moving forward against the force of the wind.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even a 4-year old understands the concept using this explanation.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="-1" LastEditDate="2013-12-28T07:57:32.800" LastActivityDate="2013-12-28T07:57:32.800" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="471" PostTypeId="1" AcceptedAnswerId="473" CreationDate="2013-12-28T05:11:29.190" Score="6" ViewCount="2477" Body="&lt;p&gt;I am 15 right now and I want to get the Certificate/License when i am 17. (17 is the age right?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much training do I need and is there any written tests etc? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of IFR training will be included/needed? &lt;/p&gt;&#xA;" OwnerUserId="259" LastEditorUserId="69" LastEditDate="2014-01-06T13:46:01.210" LastActivityDate="2014-01-06T13:46:01.210" Title="What are the requirements to get your private pilot certificate?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="472" PostTypeId="1" AcceptedAnswerId="496" CreationDate="2013-12-28T14:05:19.343" Score="22" ViewCount="7148" Body="&lt;p&gt;An assumed temperature takeoff intentionally requires a pilot to use more runway than would be normally required.  Why would someone want to do that instead of getting off the runway in the minimum distance possible?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-01-13T01:48:56.843" LastActivityDate="2014-06-05T05:29:51.627" Title="Why would an airplane pilot choose to intentionally use more runway than required for a takeoff?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;runways&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="473" PostTypeId="2" ParentId="471" CreationDate="2013-12-28T15:19:40.907" Score="5" Body="&lt;p&gt;&lt;strong&gt;In the US&lt;/strong&gt;, you'll need to be 16 old to start training and 17 to get your Private Pilot's license in a piston-powered aircraft. To get your license you'll have to have a minimum of 40 hours total time, including at least 20 with an instructor and 10 solo. You will also have to pass a written test, and get a Medical certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Details:&lt;/em&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're pursuing a Private Pilot license, per &lt;strong&gt;14 CFR §61.83&lt;/strong&gt;(a) or (b) you must be 16 years old to get a student pilot certificate (or 14 years old if you're going to train in a balloon or glider.)   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;NOTE:&lt;/strong&gt; 14 CFR mean Code of Federal Regulations, Title 14 - Aeronautics &amp;amp; Space.  §61.## means &quot;Part 61&quot; which covers Certification of Pilots and Instructors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To start training you will also have to pass a medical exam for a 3rd Class Medical Certificate, per &lt;strong&gt;14 CFR §61.23&lt;/strong&gt;(a)(3). If you're generally healthy, getting a 3rd Class Medical isn't terribly difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you successfully complete the training, per &lt;strong&gt;14 CFR §61.103&lt;/strong&gt;(a) or (b) you can get your Private Pilot license for an airplane at 17 years old (or 16 years old for a balloon or glider.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per &lt;strong&gt;14 CFR §61.109&lt;/strong&gt;(a) to get your license you will need to have completed at least 40 hours of flight time, including at least 20 hours of time with an instructor and 10 hours of solo time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, many pilots take more than the required minimum 40 hours to get their license. My suggestion is to try to complete your training in as short a calendar time as is possible. By taking lessons frequently (more than once per week) you will minimize the amount of &quot;repeat&quot; lessons, which will help you get your license with fewer hours. If you're only taking a lesson every few weeks, you will end up repeating topics and spending more than the required 40 hour minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per &lt;strong&gt;14 CFR §61.35&lt;/strong&gt;, you will have to complete a ground school program (can be with an instructor, or a &quot;home study&quot; course) before you take the Knowledge test (aka: written exam.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per &lt;strong&gt;14 CFR §61.109&lt;/strong&gt;(a)(3), you will need at least 3 hours of &quot;Instrument&quot; flight training to get your Private Pilot license. That's really not intended to be enough for you to fly safely on instruments, but to give you a basic set of skills to get out of a low-visibility situation. If you keep up with your flying, getting in Instrument rating is a GREAT idea, once you have enough hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can look up the specific wording of all of the rules at &lt;a href=&quot;http://www.ecfr.gov/&quot;&gt;http://www.ecfr.gov/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another good resource for student pilots is the Aircraft Owner's and Pilot's Association's Learn to Fly page &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Learn-to-Fly.aspx&quot;&gt;http://www.aopa.org/Pilot-Resources/Learn-to-Fly.aspx&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="264" LastActivityDate="2013-12-28T15:19:40.907" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="474" PostTypeId="1" CreationDate="2013-12-28T17:25:27.227" Score="2" ViewCount="682" Body="&lt;p&gt;What would be the most optimal shape for a quadcopter design? I have tried the cross beam design, but the center joint, though epoxied, is extremely prone to shearing off on impact.&lt;/p&gt;&#xA;" OwnerUserId="189" LastActivityDate="2014-01-02T22:54:19.940" Title="Quadcopter Design" Tags="&lt;aircraft-design&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ClosedDate="2014-01-16T00:33:01.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="475" PostTypeId="1" CreationDate="2013-12-28T17:31:13.860" Score="35" ViewCount="28398" Body="&lt;p&gt;What is the procedure for landing on an aircraft carrier? How is the checklist different from a regular landing?&lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="5517" LastEditDate="2015-02-23T22:11:30.810" LastActivityDate="2017-01-09T21:41:51.253" Title="What is the procedure for landing on an aircraft carrier?" Tags="&lt;landing&gt;&lt;aircraft-carrier&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="476" PostTypeId="2" ParentId="466" CreationDate="2013-12-28T19:19:18.603" Score="6" Body="&lt;p&gt;Every pilot knows the first thing that makes an airplane fly is money. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;as I tried to explain the 4 forces to my 6 year old daughter and trying to coach her I asked, what makes it fall out of the sky. I expected weight or gravity and she said lack of money. She was right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I try to explain it like a straw. You have four straws, one in front, one in back, one above and one below. The one below the aircraft sucks at a constant rate and never stops (gravity/weight). The one in front is the prop generating thrust. It is essentially sucking its way forward. The one in back is drag and it varies by situation but it's always trying to keep you from going forward. The final one is the one on top and that is lift. Lift is generated by the wings and sucks the airplane up. The wing creates lift by moving forward. If any of the straws win other than the front one and the top one, you crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for wind, no you can fly through no wind but the addition of wind coming at you effectively helps fill that forward straw so you can essentially take off at a lower ground speed. This is called relative wind. If your plane flies at 54 knots and you could essentially fly into a 34 knot headwind at 20 knots and achieve backwards flight at 14 knots.&lt;/p&gt;&#xA;" OwnerUserId="266" LastActivityDate="2013-12-28T19:19:18.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="477" PostTypeId="2" ParentId="471" CreationDate="2013-12-28T19:39:34.987" Score="4" Body="&lt;p&gt;One thing to note is everything &lt;a href=&quot;https://aviation.stackexchange.com/a/473/64&quot;&gt;in user264's answer&lt;/a&gt; is the minimum required and solely lies upon the individual to:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Study - yes flying an airplane does require some academics, basic math, navigation, basic physics. The more of the basic reading you do up front will help very bit with keeping hours down on learning to fly&lt;/li&gt;&#xA;&lt;li&gt;Your personal willingness to be humbled - flight is an art - you will hear it at some point, every pilot judges their flight by the landing. The reason for this is it is the hardest part of flying. All the training you receive will be things to teach you about landing. Do well with those and they will help you to make good landings. It will be a challenge but well worth it&lt;/li&gt;&#xA;&lt;li&gt;Listen and ask lots of questions - your instructor is trying to lead an art class.&lt;/li&gt;&#xA;&lt;li&gt;On average it takes 50-70 hours to make a private pilot. Usually closer to 70&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="266" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2013-12-28T20:59:17.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="478" PostTypeId="2" ParentId="474" CreationDate="2013-12-28T20:47:50.777" Score="2" Body="&lt;p&gt;There's really no &quot;optimal design&quot; for a quadracopter - there are many &lt;em&gt;good&lt;/em&gt; designs, each of which is a compromise between several factors like endurance, performance, flight handling characteristics, and durability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question seems to imply that you want something that's geared toward durability (and probably beginner-friendly flight handling characteristics) since you seem to be worried about things &quot;shearing off on impact&quot;, and I'm going to break this to you as gently as I can: &lt;em&gt;No aircraft is designed to crash&lt;/em&gt;.&lt;br&gt;&#xA;Some designs are &lt;em&gt;better&lt;/em&gt; at crashing than others -- in manned aircraft that means they're designed to let the occupants walk away, and in unmanned aircraft it means they're designed for you to put the pieces back together as quickly as possible.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The cross-beam design isn't really built for durability. It's the sport model - light, fast, maneuverable, and often just a little bit unsafe.&lt;br&gt;&#xA;You can improve its crashworthiness by &lt;strong&gt;&lt;em&gt;designing it to break apart&lt;/em&gt;&lt;/strong&gt; on impact (i.e. rather than trying to beef up the center hub build it so the beams can detach and be easily reattached). This will hopefully reduce the work you have to do after a crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an alternate design though, consider something like the one pictured below:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/vFg9t.jpg&quot; alt=&quot;&amp;quot;full frame&amp;quot; quadracopter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These full-frame quadracopters are the kind you'll often find at mall kiosks (made out of styrofoam). They're great for beginners because the frame design braces itself and can take substantially more abuse than simple cross-beam designs.&lt;br&gt;&#xA;The design also inherently protects the propeller blades from whacking into things when you lose control (and innocent bystanders from whacking into the propeller blades) which is a nice bonus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This particular example has the motors mounted on a modified cross-beam structure under the copter, but designs where the mounting comes from above &amp;amp; an undercarriage is provided for landing are also out there in the wild. Another option is a frame thick enough that your propeller/motor attachments can come out of the middle of the frame, protecting them further.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2013-12-28T20:53:29.477" LastActivityDate="2013-12-28T20:53:29.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="479" PostTypeId="2" ParentId="475" CreationDate="2013-12-28T21:12:10.017" Score="3" Body="&lt;p&gt;Don't know about a checklist, but I know that when they get ready to land (as in, they are about to touch down on the carrier) they set the engines to max thrust, just incase they do not hit the cable to slow them down. I thought that &lt;a href=&quot;http://www.youtube.com/watch?v=ecoeU2OugSg&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; about it was cool.&lt;/p&gt;&#xA;" OwnerUserId="259" LastEditorUserId="97" LastEditDate="2014-02-07T00:15:53.637" LastActivityDate="2014-02-07T00:15:53.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="480" PostTypeId="2" ParentId="475" CreationDate="2013-12-28T21:42:29.563" Score="17" Body="&lt;p&gt;There are a few differences in landing on an aircraft carrier versus on the ground.&lt;br&gt;&#xA;I've got no carrier (or military) experience so I can't really speak to the checklists, except to say that they would be slightly different for each aircraft, but it's a subject that's interesting to me so I've done a little digging over the years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the differences that always stick out in my mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The whole airport is moving&lt;br&gt;&#xA;When setting up for launch or recovery carriers typically &quot;steam into the wind&quot;, creating a combined headwind of whatever the winds on the sea are, plus the speed of the carrier.  This minimizes the deck speed of landing aircraft, and is advantageous for takeoffs as well.&lt;br&gt;&#xA;As an example, if you've got a 10 knot breeze and the carrier is steaming along at 30 knots into the wind the effective headwind on deck is 40 knots, so aircraft landing have a deck speed (ground speed) about 40 knots lower than their indicated airspeed, which makes decelerating them easier.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Arresting_gear#Sea-based_systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;The arresting gear (Hook &amp;amp; Wires)&lt;/a&gt;&lt;br&gt;&#xA;Even with the headwind above, modern carrier-based aircraft - with the exception of helicopters - touch down with some substantial forward velocity. They would not be able to stop using conventional thrust reversers and brakes, so in order to actually &lt;em&gt;STOP&lt;/em&gt; the aircraft on the deck arresting gear is used to rapidly decelerate it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The &quot;full-throttle touchdown&quot;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/479/64&quot;&gt;As Cameron pointed out&lt;/a&gt;, part of normal carrier landing procedure is to set the aircraft's engines to maximum thrust as soon as your wheels hit the deck, in preparation for a &quot;bolter&quot; if you miss the arresting gear (or it fails to stop your aircraft).&lt;br&gt;&#xA;This is due to the short deck -- there is generally insufficient distance for either a rollout/stopping the aircraft with brakes or the pilot's reaction time for a &quot;touch-and-go&quot; when they realize they missed the wire. With the engines at full thrust the pilot is already accelerating and preparing to climb out and try again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The approach slope guidance &lt;a href=&quot;http://en.wikipedia.org/wiki/Optical_landing_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;(Optical landing system)&lt;/a&gt;&lt;br&gt;&#xA;This is the &quot;ball&quot; you hear pilots talking about in all those naval aviation movies, this is the equivalent of the various land-based approach slope systems (PAPIs/VASIs).  In the US Navy the optical landing system is controlled by the Landing Signal Officer (LSO), who also issues instructions to the pilot as necessary to facilitate safe recovery of the aircraft. My understanding is other navies with aircraft carriers have a similar person on deck.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that all of the above is for fixed-wing aircraft.&lt;br&gt;&#xA;Helicopters can and do land on aircraft carriers too, but their procedures are much closer to &quot;normal&quot; (land) landings, because of the nature of helicopters.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2013-12-28T21:56:17.227" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="481" PostTypeId="1" AcceptedAnswerId="10072" CreationDate="2013-12-29T07:47:17.957" Score="22" ViewCount="10566" Body="&lt;p&gt;Is it possible for the pilot to be held responsible for violating a Temporary Flight Restriction if the controller makes a mistake while you are operating under an Instrument flight plan (ie: does not deviate you around it, or allows you to go through it without clearing you with the responsible body)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a commonly held belief that the pilot is immune from TFRs while under IFR, but I found a forum thread that seems to indicate the opposite, where both the pilot and the controller were at fault and both received a suspension.  &lt;a href=&quot;http://www.studentpilot.com/interact/forum/archive/index.php/t-17212.html&quot;&gt;http://www.studentpilot.com/interact/forum/archive/index.php/t-17212.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Bonus: Can anyone find a more official reference for that story, and whether there was any legal followup from AOPA Legal or otherwise?)&lt;/p&gt;&#xA;" OwnerUserId="27" LastEditorUserId="72" LastEditDate="2014-03-03T05:32:51.990" LastActivityDate="2015-07-28T23:49:00.540" Title="Can you bust a TFR while operating under IFR?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;instrument-flight-rules&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="482" PostTypeId="1" AcceptedAnswerId="487" CreationDate="2013-12-29T08:11:42.430" Score="17" ViewCount="1822" Body="&lt;p&gt;Forgive my total lack of aviation knowledge. I just flew out of &lt;a href=&quot;http://en.wikipedia.org/wiki/File%3aSFO_map.png&quot;&gt;SFO&lt;/a&gt; and was fascinated by the fact that pairs of planes alternated between departing on 28L + 28R (simultaneously) and arriving on 19L/R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is this: What amount of micromanagement from ATC exists to keep taking-off planes on schedule and not running into the landing planes, especially in cases where runways cross? How much information does the tower give to the taxiing planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="268" LastEditorUserId="69" LastEditDate="2013-12-29T17:05:15.893" LastActivityDate="2015-04-08T14:42:33.633" Title="How does ATC handle arriving/departing runways that cross?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="484" PostTypeId="1" AcceptedAnswerId="486" CreationDate="2013-12-29T16:45:53.397" Score="19" ViewCount="4086" Body="&lt;p&gt;What is the purpose of the piece of string taped to a glider canopy? Is it effectively a turn coordinator, but then what advantages would it have over a gauge such as the ones fitted in powered aircraft?&lt;/p&gt;&#xA;" OwnerUserId="269" LastEditorUserId="3504" LastEditDate="2015-02-09T23:58:03.707" LastActivityDate="2015-02-10T16:20:14.400" Title="What is the purpose of the string taped to the front of the canopy on gliders?" Tags="&lt;glider&gt;&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="485" PostTypeId="2" ParentId="481" CreationDate="2013-12-29T16:47:14.067" Score="5" Body="&lt;p&gt;I think that you are confusing the rules for Restricted airspace and those for TFR's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the type of TFR, there are different regulation that cover them, but they are very similar.  For instance, Presidential TFR's are governed by the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=15119b7230cff7cb1aacbc8f51c94128;rgn=div8;view=text;node=14:2.0.1.3.10.2.4.24;idno=14;cc=ecfr&quot; rel=&quot;nofollow&quot;&gt;§91.141&lt;/a&gt;   Flight restrictions in the proximity of the Presidential and&#xA;  other parties. &lt;strong&gt;No person may operate an aircraft over or in the&#xA;  vicinity of&lt;/strong&gt; any area to be visited or traveled by the President, the&#xA;  Vice President, or other public figures &lt;strong&gt;contrary to the restrictions&#xA;  established by the Administrator and published in a Notice to Airmen&#xA;  (NOTAM)&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(emphasis mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that it specifically says that &quot;No person may operate an aircraft...contrary to the restrictions established by the Administrator and published in a Notice to Airmen&quot;.  Operating IFR does not preclude you from that responsibility.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Restricted areas on the other hand are covered by the following regulation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.19&quot; rel=&quot;nofollow&quot;&gt;§91.133&lt;/a&gt;   Restricted and prohibited areas. (a) No person may operate&#xA;  an aircraft within a restricted area (designated in part 73) contrary&#xA;  to the restrictions imposed, or within a prohibited area, &lt;strong&gt;unless that person has the permission of the using or controlling agency, as appropriate.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(emphasis mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ATC clears you into a restricted area (or even assigns a heading which takes you into it), they have given you the required permission.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-12-08T22:14:50.630" LastActivityDate="2014-12-08T22:14:50.630" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="486" PostTypeId="2" ParentId="484" CreationDate="2013-12-29T16:51:15.600" Score="22" Body="&lt;p&gt;Yes, the yaw string on the canopy of a glider is there to show you whether or not you are coordinated, especially during turns.  It indicates the relative wind, so will be straight unless the glider is slipping or skidding, in which case it will swing to the left or right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those not familiar with them, here is an image that shows one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X8TOr.jpg&quot; alt=&quot;Glider yaw string&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Yaw_string&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, they are also used on other aircraft (even jet fighters and the U-2!) although they are used in almost every glider.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the advantages that it has over an actual instrument installed in the panel are numerous:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is directly in your line of sight while looking outside, so you don't have to look at the instrument panel to see if you are yawing.&lt;/li&gt;&#xA;&lt;li&gt;It is more sensitive &lt;/li&gt;&#xA;&lt;li&gt;It reacts faster to changes&lt;/li&gt;&#xA;&lt;li&gt;It is cheaper&lt;/li&gt;&#xA;&lt;li&gt;It is lighter&lt;/li&gt;&#xA;&lt;li&gt;It doesn't require electricity (or even an electrical system on the glider)&lt;/li&gt;&#xA;&lt;li&gt;It costs far less to maintain&lt;/li&gt;&#xA;&lt;li&gt;It is easy to recognize when it fails (it's either there or not)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2013-12-30T15:38:20.753" LastActivityDate="2013-12-30T15:38:20.753" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="487" PostTypeId="2" ParentId="482" CreationDate="2013-12-29T17:19:32.500" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7110.65V_with_CHG_2_.pdf&quot;&gt;Chapter 9 - Departure Procedures and Separation&lt;/a&gt; of the FAA Order titled &quot;Air Traffic Control&quot; covers the procedures that are used for aircraft departures, including those cases where they have intersecting runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are numerous procedures that they follow that are specific to intersecting runways, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;3-9-4 - LINE UP AND WAIT (LUAW)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the tower has an airplane Line Up And Wait (taxi onto the active runway but not actually takeoff) because of another airplane that is landing or taking off on an intersecting runway, they must inform them of the other airplane and why they are not taking off.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;3-9-7 - WAKE TURBULENCE SEPARATION FOR INTERSECTION DEPARTURES&lt;/li&gt;&#xA;&lt;li&gt;3-9-8 - INTERSECTING RUNWAY SEPARATION&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This probably covers most of what you are asking about, and has some great pictures showing when they are allowed to clear another airplane for takeoff in different situations.  For instance, they can't clear an airplane for takeoff with another airplane landing on an intersecting runway until after they have passed their runway.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that there are similar procedures in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7110.65V_with_CHG_2_.pdf&quot;&gt;Chapter 10 - Arrival Procedures and Separation&lt;/a&gt;   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, there are &lt;strong&gt;lots&lt;/strong&gt; of extra procedures that must be followed when using intersecting runways simultaneously, but they also get a lot of operational benefits when they can do it so are able to get a lot more airplanes on and off the ground in the same amount of time. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="679" LastEditDate="2015-04-08T07:24:38.660" LastActivityDate="2015-04-08T07:24:38.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="488" PostTypeId="2" ParentId="472" CreationDate="2013-12-29T18:05:51.787" Score="2" Body="&lt;p&gt;Airshow pilots will sometimes use more runway than necessary.  They'll get the wheels off the ground but remain in ground effect (sometimes only a foot off the runway, which I count as &quot;still using the runway&quot;) while accelerating.  The extra speed will permit them to make a dramatic vertical climb that's a lot steeper than Vy or Vx would permit.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2013-12-29T18:05:51.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="489" PostTypeId="1" AcceptedAnswerId="490" CreationDate="2013-12-29T21:53:06.990" Score="31" ViewCount="3861" Body="&lt;p&gt;I have heard of pilots rolling airplanes that aren't approved for it (Cessna 172, Learjets, etc.), and other than the obvious legal issues, are there any mechanical or safety reasons to avoid it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;DISCLAIMER&lt;/strong&gt;&lt;br&gt;&#xA;I do not advocate doing anything (like this) that is not legal, but am looking more for additional reasons that I can use to &lt;strong&gt;dissuade&lt;/strong&gt; people from doing this when they say that it &lt;em&gt;isn't hurting anyone&lt;/em&gt; or something along those lines.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="64" LastEditDate="2013-12-30T06:07:55.143" LastActivityDate="2020-10-05T14:57:43.570" Title="Is it safe to roll an airplane that isn't approved for it?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;aerobatics&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="490" PostTypeId="2" ParentId="489" CreationDate="2013-12-29T23:26:16.217" Score="61" Body="&lt;p&gt;There are a lot of good reasons not to roll such an airplane.&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If the plane has gyroscopic instruments, you might tumble them (cause the spinning gyro to hit the inside of the instrument).  This can be expensive.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You might easily over-stress the air frame.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Load_factor_%28aeronautics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Normal category light aircraft are rated to -1.5 to +3.8Gs&lt;/a&gt;.  (That's for a new aircraft)  A botched roll can easily hit 4.5 or higher.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;If you over stress the air frame, you might just put a lot of very expensive &amp;quot;wrinkles&amp;quot; in the skin that would be very hard to explain to the FBO, your boss, or the insurance company.  Trashing the gyros would be cheaper.&lt;/p&gt;&#xA;&lt;p&gt;If you're not lucky, the wings fold up and you fall out of the sky.  It's a stupid way to die.&lt;/p&gt;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;Non-aerobatic aircraft typically have limited elevator authority; once upside down, you might find it very difficult to keep the nose pushed up high enough to keep the roll going.  Turning a botched roll into a &amp;quot;split-S&amp;quot; is one of the worst &amp;quot;recovery&amp;quot; mistakes you can make, and you're setting yourself up for it.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Non-aerobatic aircraft often have gravity-feed fuel systems.  A little bit of 0 or negative &amp;quot;G&amp;quot; and it will get very very quiet in the plane.  Some people consider this silence detrimental to the continued safety of the flight.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Non-aerobatic aircraft rarely have inverted oil systems.  As the engine gets quiet, it also loses most of its lubrication.  Bare metal on metal friction can be detrimental to achieving &lt;a href=&quot;http://en.wikipedia.org/wiki/Time_between_overhaul&quot; rel=&quot;nofollow noreferrer&quot;&gt;TBO&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;Having said all that, in the hands of an &lt;em&gt;expert&lt;/em&gt;, it is &lt;em&gt;technically&lt;/em&gt; possible to barrel roll most aircraft.&lt;/p&gt;&#xA;&lt;p&gt;A good way to tell if you're an expert is to call your insurance company and tell them exactly what you plan to do.  If they'll quote you affordable coverage, you might be an expert.&lt;/p&gt;&#xA;&lt;p&gt;Obligatory links because if I don't include them someone else will:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=Ra_khhzuFlE&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tex Johnson rolling a 707&lt;/a&gt;.  I'm pretty sure he'd never get away with this today.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/W2-9BL7sllk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bob Hoover pouring iced tea&lt;/a&gt;.  Bob Hoover is beyond expert.  Way, way, beyond expert.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr/&gt;&#xA;If you want to roll an airplane, contact your local aerobatic club.  In the US and some countries, it's the [International Aerobatic Club][5].  Get some competent dual instruction in a suitably rated airplane.&#xA;" OwnerUserId="52" LastEditorUserId="52344" LastEditDate="2020-10-05T14:57:43.570" LastActivityDate="2020-10-05T14:57:43.570" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="491" PostTypeId="2" ParentId="472" CreationDate="2013-12-30T01:12:31.247" Score="3" Body="&lt;p&gt;It's basically a question of economics. Derating your takeoff means using a lower thrust setting for the engine which means less wear and thus less money spent on maintenance. &lt;/p&gt;&#xA;" OwnerUserId="272" LastActivityDate="2013-12-30T01:12:31.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="492" PostTypeId="1" AcceptedAnswerId="32460" CreationDate="2013-12-30T03:02:06.800" Score="20" ViewCount="7361" Body="&lt;p&gt;In remote areas that have no radar (oceanic airspace, etc.) how is aircraft separation maintained so that airplanes don't get too close?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do areas that normally have radar do when there is a sudden radar outage?  There are airplanes going everywhere, not necessarily on standard airways, and a lot of them are being given radar vectors.  What happens when the screens go dark?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14957" LastEditDate="2016-10-17T17:53:09.657" LastActivityDate="2016-10-21T20:13:12.010" Title="How are aircraft separated in a non-radar environment?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;radar&gt;&lt;surveillance&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="493" PostTypeId="2" ParentId="492" CreationDate="2013-12-30T03:49:58.423" Score="13" Body="&lt;p&gt;For oceanic airspace, flights proceed along specified tracks and altitudes specified in their filed flight plan. From there, once they leave radar-controlled airspace, radio reports are made to ATC, who ensure that aircraft are appropriately separated if a flight needs to change its track or altitude. See &lt;a href=&quot;https://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot;&gt;the wiki article&lt;/a&gt; the North Atlantic tracks, which give a good overview on the track system. Specifically:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Prior to departure, airline flight dispatchers/flight operations officers will determine the best track based on destination, aircraft weight, aircraft type, prevailing winds and Air Traffic Control route charges. The aircraft will then contact the Oceanic Center controller before entering oceanic airspace and request the track giving the estimated time of arrival at the entry point. The Oceanic Controllers then calculate the required separation distances between aircraft and issue clearances to the pilots. It may be that the track is not available at that altitude or time so an alternate track or altitude will be assigned. Planes cannot change assigned course or altitude without permission.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Contingency plans exist within the North Atlantic Track system to account for any operational issues that occur. For example, if an aircraft can no longer maintain the speed or altitude it was assigned, the aircraft can move off the track route and fly parallel to its track, but well away from other aircraft. Also, pilots on North Atlantic Tracks are required to inform air traffic control of any deviations in altitude or speed necessitated by avoiding weather, such as thunderstorms or turbulence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm going to leave the &quot;what happens when things break&quot; to someone else.&lt;/p&gt;&#xA;" OwnerUserId="222" LastEditorUserId="222" LastEditDate="2013-12-30T05:15:06.220" LastActivityDate="2013-12-30T05:15:06.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="494" PostTypeId="2" ParentId="492" CreationDate="2013-12-30T04:23:38.827" Score="12" Body="&lt;p&gt;When the screens go dark ATC breaks out the flight progress strips (and possibly the &lt;a href=&quot;http://www.avweb.com/news/sayagain/182641-1.html?redirected=1&quot;&gt;shrimp boats&lt;/a&gt; or other airplane-substitutes to lay on a map &amp;amp; push around) and uses brain power to substitute for the computer and radar. Check out &lt;a href=&quot;http://www.avweb.com/news/sayagain/191625-1.html?redirected=1&quot;&gt;one of my favorite &quot;Say Again?&quot; columns over on AvWeb&lt;/a&gt; which talks a little bit about it (and you can find lots more if you browse the archives).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Broadly, there's a few implications to non-radar operations - both routine and &quot;when stuff breaks&quot; - most of which are concessions to safety. The one most pilots will feel, and the biggest safety item, is that &quot;random RNAV routes can only be approved in a radar environment&quot; (you'll find that gem in the AIM, but the translation is this: &quot;GPS Direct? YOU NO CAN HAS!&quot;).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To facilitate separation in a non-radar environment the controllers are going to chuck you (and every other IFR flight) on airways, at standard IFR altitudes, quite probably with a specified airspeed, and they're going to route you navaid-to-navaid.&lt;br&gt;&#xA;The idea here is simple: &quot;You gotta put them together to keep them apart&quot;: By ensuring all flights are on known airways, at known altitudes, and at known speeds controllers have a good idea of who is where in their airspace.  They will supplement this mental picture by asking pilots to report crossing certain fixes (intersections/radials), so that they know exactly where that flight is when they make their report (which will help them account for winds aloft, and give them an idea of what the flight's ground speed is in addition to the airspeed they're asking them to fly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the above provides IFR-to-IFR separation, which is what the controller is concerned with. IFR-to-VFR separation (which is normally supplemented by radar) becomes the responsibility of the pilots (&quot;See and Avoid&quot;) - this means it's largely a factor of altitude (that 500-foot difference between IFR and VFR cruising altitudes and those cloud clearance requirements should start to seem pretty important right about now).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2013-12-30T04:23:38.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="495" PostTypeId="2" ParentId="472" CreationDate="2013-12-30T04:56:36.390" Score="27" Body="&lt;p&gt;Imagine you're doing a takeoff at a high density altitude. You need more runway to get up to speed because your engine is producing less power and you need to move faster to move the same amount of air over your wings as you would at a lower DA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft can pretend the DA is higher by using a higher than normal temperature when calculating takeoff information. In jets with automated engine controllers, this setting -in a round about way- allows you to set the engines to produce only the minimum thrust required to get off the ground safely. Since that results in less thrust, there is less wear on the engine and that adds up significantly over time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your trade-off for this decreased wear is that you need more runway, which is usually readily available. If you suddenly need full power you just move the throttle to the Take-Off/Go-Around (TOGA) or emergency power setting (or push a TOGA button on the throttle), which overrides the temperature preset.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2013-12-30T04:56:36.390" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="496" PostTypeId="2" ParentId="472" CreationDate="2013-12-30T12:54:00.527" Score="20" Body="&lt;p&gt;An assumed temperature takeoff (also known as &quot;flex&quot; on Airbus/Fokker aircraft) is where the engine thrust is reduced to match the performance on a higher-temperature day, up to either the maximum thrust reduction allowed or the maximum assumed temperature that meets takeoff distance requirements. Unlike a derate, assumed temperature takeoffs do not reduce the minimum control speed used for calculating takeoff speeds ($V_{MCG}$ for $V_1$, $V_{MCA}$ for $V_2$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The minimum selectable temperature is the lowest temperature beyond the flat rating temperature range (the range of temperatures where maximum thrust is achievable, limited by an engine control unit), and the highest temperature is the temperature at which the maximum thrust reduction allowed will be met. Except with specific certification and approval (such as 40% flex on the A340), such a procedure must not reduce the thrust beyond 25% of the nominal takeoff thrust (either full rate or a takeoff derate). For example, the range of assumed temperatures permitted is 30-75°C (flat rated to $ISA+15$, thrust at 75°C is 75% of normal rating).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason for performing an assumed temperature takeoff is to conserve engine life, therefore reducing maintenance costs. According to Boeing, engine wear exponentially increases with the takeoff thrust used -- with engines costing about 10 million USD each, this has the potential to save a lot of money for airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are taking off using assumed temperature, you may (but are not required to) add thrust to TOGA in the case of an emergency, however if you are using a takeoff derate, you must not increase the thrust beyond the derated N1, as this could cause a loss of control (higher thrust = higher actual $V_{MCG}$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all aircraft allow assumed temperature in conjunction with derates. For example, you can only select a derate &lt;em&gt;or&lt;/em&gt; a flex temperature on all Airbus aircraft (if a derate option is offered).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: do not attempt to &quot;copy the jet jocks&quot; in a piston aircraft and attempt a reduced throttle takeoff: only at takeoff throttle levels is extra fuel injected for cooling and reduction beyond this point could result in CHT levels rising to unacceptable levels, increasing the risk of engine damage.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="97" LastEditDate="2014-04-17T00:03:17.487" LastActivityDate="2014-04-17T00:03:17.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="497" PostTypeId="1" CreationDate="2013-12-30T13:32:30.017" Score="7" ViewCount="1588" Body="&lt;p&gt;How often does an autopilot update the position of the ailerons (or any other control surface) during cruise? Per second, per minute, or something else?&lt;/p&gt;&#xA;" OwnerDisplayName="user278" LastEditorUserId="39" LastEditDate="2013-12-30T19:07:29.520" LastActivityDate="2014-04-16T23:41:23.027" Title="How often does an autopilot update control surfaces' positions?" Tags="&lt;autopilot&gt;&lt;flight-controls&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="498" PostTypeId="1" AcceptedAnswerId="531" CreationDate="2013-12-30T19:14:07.090" Score="-1" ViewCount="2300" Body="&lt;p&gt;In the newest aircraft, autopilots are of paramount importance, but how are they designed? What is the hardware used to run them (I guess it is quite different from my laptop)? What is the software (language) used and what are its characteristics (regular clock counter, robust, ...)? This question concerns mainly civil aircraft since I guess that it will be hard to get answers for military ones!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt; To make this question answerable and less broad, I would like to have answers focusing on turbojet engine aircraft used as civilian carriers (A320 seems a good candidate to me but I am opened to any other airplane fitting the description).&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="113" LastEditDate="2013-12-30T23:21:26.313" LastActivityDate="2014-01-01T19:58:04.543" Title="What are the technologies used in A320 autopilot?" Tags="&lt;autopilot&gt;&lt;avionics&gt;" AnswerCount="2" CommentCount="9" ClosedDate="2014-01-13T00:20:44.820" ContentLicense="CC BY-SA 3.0" />
  <row Id="499" PostTypeId="1" AcceptedAnswerId="503" CreationDate="2013-12-30T20:31:16.933" Score="10" ViewCount="1905" Body="&lt;p&gt;How do turbochargers improve engine performance at high altitudes / density altitudes?&lt;br&gt;&#xA;Could you also address how this benefit could become a liability at low density altitudes, for example when the density altitude is negative?&lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="21" LastEditDate="2013-12-31T00:23:08.930" LastActivityDate="2019-05-31T23:31:23.777" Title="How do turbochargers aid engine performance as density altitude increases?" Tags="&lt;piston-engine&gt;&lt;density-altitude&gt;&lt;turbocharged&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="500" PostTypeId="1" AcceptedAnswerId="504" CreationDate="2013-12-30T21:03:28.623" Score="15" ViewCount="2256" Body="&lt;p&gt;As part of a project I'm doing I plotted the flight paths of about 2000 flights around the globe, I noticed over both the North Atlantic and Pacific that there is a pattern to the flight paths:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IEZEP.png&quot; alt=&quot;North Atlantic Flights&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should be able to see Europe on the right and the USA on the left. Why is there such a common pattern in the flight paths? They all seem to cross every 10 degrees longitude and 1 degree latitude. Is there any explanation for this?&lt;/p&gt;&#xA;" OwnerUserId="281" LastEditorUserId="14897" LastEditDate="2018-03-14T18:50:52.943" LastActivityDate="2018-03-14T18:50:52.943" Title="Do autopilots force the aircraft to fly over certain coordinates?" Tags="&lt;autopilot&gt;&lt;flight-planning&gt;&lt;navigation&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="501" PostTypeId="2" ParentId="500" CreationDate="2013-12-30T21:58:33.510" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://skyvector.com/?ll=52.88415911423284,-67.39160156101475&amp;amp;chart=304&amp;amp;zoom=9&quot; rel=&quot;nofollow&quot;&gt;This map&lt;/a&gt; should help explain it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navigation points are spaced out evenly, and the planes aim for those points.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2013-12-30T21:58:33.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="502" PostTypeId="2" ParentId="500" CreationDate="2013-12-30T22:08:12.680" Score="9" Body="&lt;p&gt;It's not that the &lt;em&gt;autopilot&lt;/em&gt; forces the airplane over certain coordinates.  The autopilot follows a programmed flight plan (that is typically entered by the pilot or the dispatcher).  There is a huge database of standard reporting points that the flight plan is made up of, which is why you see similar routes.  So in answer to your question, it's not the autopilot, but rather there are published reporting point and standard routes that most pilots program their autopilot to follow.  The autopilot is the servant, not the master :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This helps with search and rescue (heaven forbid!) efforts if an airplane is lost, then it can give SAR a good starting point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS is supposed to help create more direct routes, but total reliance on GPS-aided navigation isn't fully implemented world-wide.&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2013-12-30T22:08:12.680" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="503" PostTypeId="2" ParentId="499" CreationDate="2013-12-30T22:11:03.383" Score="11" Body="&lt;p&gt;An oversimplification for sure: Turbochargers essentially compress the air going into the engine (cylinders) to maintain (near) sea level pressure internally, so the external density altitude doesn't affect the performance of the engine.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;liability&quot; at low density altutudes is that it is possible to over-boost the engine, potentially damaging it. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/78/caution-low-density-altitude&quot;&gt;the related question&lt;/a&gt; for more in-depth explanation and the liability of having a turbocharger at low density altitude.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2013-12-30T22:29:37.430" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="504" PostTypeId="2" ParentId="500" CreationDate="2013-12-30T22:14:16.217" Score="15" Body="&lt;p&gt;Historically, when flying over land, aircraft follow jet routes or airways (same thing, different altitude), which are pre-defined routes from one land-based navigational station (such as VOR) to another. Variations in terrain (such as mountains), location of the VOR, and other airspace considerations all affect the location of routes available to aircraft in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over water, however, there are no terrain features, navigation is not conducted primarily with VOR, and there are far fewer airspace concerns in general.  Therefore, waypoints are placed in a grid (why not?), which encourages uniformity in flight paths over time, which is what you have discovered.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2013-12-30T22:14:16.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="505" PostTypeId="2" ParentId="498" CreationDate="2013-12-30T23:36:25.827" Score="2" Body="&lt;p&gt;Hopefully the following information will prompt a more specific question (or series of questions):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I looked up S-TEC autopilots because they have an STC (supplemental type certificate) for their autopilot system for over 1,600 models of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An &lt;strong&gt;autopilot&lt;/strong&gt; is an avionics system designed to serve two primary purposes:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Enhance a pilot’s flight control capabilities&lt;/li&gt;&#xA;  &lt;li&gt;Reduce cockpit workload by putting the airplane in an automatic flight mode&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An autopilot consists of three &lt;em&gt;basic components&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Mode selector/programmer&lt;/strong&gt; (The device that allows the pilot to program the autopilot to achieve the intended flight profile. This may interact with other avionics, such as a GPS unit)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Computer&lt;/strong&gt; (This receives the information from the programmer or avionics and sends the appropriate signal to the actuators)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Actuators&lt;/strong&gt; (The servos or motors which physically move the aircraft's control surfaces)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;An autopilot system can be either &lt;em&gt;position-based&lt;/em&gt; or &lt;em&gt;rate-based&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Position or attitude autopilots&lt;/strong&gt; typically use the pilot’s attitude indicator as a gyroscope signal source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Rate-based autopilot systems&lt;/strong&gt; use rate gyros and/or accelerometers as primary sensors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many features and functions of an autopilot which are outlined in the referenced PDF file below, but to give you an overview:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing Stabilizer (Wing Leveler). &lt;/li&gt;&#xA;&lt;li&gt;Heading Mode. &lt;/li&gt;&#xA;&lt;li&gt;Course Tracking and Coupling. &lt;/li&gt;&#xA;&lt;li&gt;Course Deviation Warning. &lt;/li&gt;&#xA;&lt;li&gt;Dual Mode Intercept.&lt;/li&gt;&#xA;&lt;li&gt;Roll Steering.&lt;/li&gt;&#xA;&lt;li&gt;Altitude Hold.&lt;/li&gt;&#xA;&lt;li&gt;Vertical Speed.&lt;/li&gt;&#xA;&lt;li&gt;Pre-Selected Altitude Capture.&lt;/li&gt;&#xA;&lt;li&gt;Glideslope Coupling.&lt;/li&gt;&#xA;&lt;li&gt;Trim.&lt;/li&gt;&#xA;&lt;li&gt;Control Wheel Steering.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Fundamentally, autopilots typically perform the following tasks:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maintaining Assigned Altitude and Heading.&lt;/li&gt;&#xA;&lt;li&gt;Holding a heading&lt;/li&gt;&#xA;&lt;li&gt;Tracking a VOR, GPS, LORAN or LOC signal&lt;/li&gt;&#xA;&lt;li&gt;Intercepting the course&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each one of these aspects of an autopilot could provide several ideas for questions that could help you get a fuller picture of all the technologies involved in autopilots, and perhaps help you limit the scope of your question to something that might not require textbook-length answer :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps in your quest!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;S-TEC Autopilot Overview:&#xA;&lt;a href=&quot;http://sharepoint.s-tec.com/Documentation/Shared%20Documents/Autopilot%20Selection/AutoPilotBook.pdf&quot; rel=&quot;nofollow&quot;&gt;http://sharepoint.s-tec.com/Documentation/Shared%20Documents/Autopilot%20Selection/AutoPilotBook.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;S-TEC Pilot Operating Handbooks:&#xA;&lt;a href=&quot;http://sharepoint.s-tec.com/Documentation/default.aspx&quot; rel=&quot;nofollow&quot;&gt;http://sharepoint.s-tec.com/Documentation/default.aspx&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Garmin also makes a GA autopilot called the GFC 700 which integrates into their Garmin 1000 flight deck.  More info here: &lt;a href=&quot;http://www8.garmin.com/learningcenter/training/gfc700/&quot; rel=&quot;nofollow&quot;&gt;http://www8.garmin.com/learningcenter/training/gfc700/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2013-12-30T23:36:25.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="506" PostTypeId="1" AcceptedAnswerId="507" CreationDate="2013-12-30T23:51:47.230" Score="14" ViewCount="799" Body="&lt;p&gt;Autopilots used in piston GA usually do not have throttle control. They only manage the control surfaces. However to trim an aircraft one needs to play on both throttle setting (and more physically, thrust) and control surface deflections (aerodynamic forces). What happens if the autopilot cannot trim the aircraft due to the propulsion settings? Is there any alert from the autopilot for the pilot?&lt;/p&gt;&#xA;" OwnerUserId="113" LastActivityDate="2013-12-31T00:21:02.583" Title="What happens when autopilot and propulsion settings do not match?" Tags="&lt;autopilot&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="507" PostTypeId="2" ParentId="506" CreationDate="2013-12-31T00:21:02.583" Score="9" Body="&lt;p&gt;It all depends on the autopilot, but generally no. If for example, you tell the autopilot to climb at 300 fpm, it will keep adjusting pitch to do just that.   As you climb higher (without changing the power) the autopilot will keep increasing pitch to maintain the set vertical speed.  Eventually the airplane will get too slow because of the increased pitch and can even stall.  Some autopilots have pitch limits or monitor the stall inputs and automatically disconnect before it gets to this point, but others don't.  It is very important to know your autopilot and to monitor it at all times to make sure that it is doing what you want. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-31T00:21:02.583" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="508" PostTypeId="1" CreationDate="2013-12-31T01:04:54.037" Score="11" ViewCount="988" Body="&lt;p&gt;Is there a technique anyone has to make it easier to give PIREPs (mnemonics, etc?)  I'd like to be able to give them while I fly but I can never find the expected format handy, so it ends up being a hassle.  If there's a trick anyone has to make it easy to give one, please share!&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="1696" LastEditDate="2015-02-11T22:56:44.360" LastActivityDate="2015-02-11T22:56:44.360" Title="What is an easy format for giving pilot reports?" Tags="&lt;air-traffic-control&gt;&lt;weather&gt;&lt;radio-communications&gt;&lt;pirep&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="509" PostTypeId="1" AcceptedAnswerId="511" CreationDate="2013-12-31T01:12:45.777" Score="6" ViewCount="1894" Body="&lt;p&gt;As a PPL holder in the USA, what do I need to have on the aircraft (or otherwise?) in order to be able to legally fly at night?  LSAs are much cheaper to operate, so it looks very tempting in order to be able to fly more hours, I'm just concerned about getting stuck out at dusk, especially in winter.&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="97" LastEditDate="2014-01-28T17:34:16.040" LastActivityDate="2014-01-28T17:34:16.040" Title="What is needed to operate a LSA aircraft at night?" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="510" PostTypeId="2" ParentId="328" CreationDate="2013-12-31T02:01:50.467" Score="1" Body="&lt;p&gt;Unless there is a charted B or C airspace, you are not &lt;em&gt;REQUIRED&lt;/em&gt; to contact the approach facility.  Different towers may have different opinions on what they prefer you to do, however.  Some have TRSAs (responsibility is mapped out, and you can participate if you want), and some just mysteriously have a approach/departure frequency listed and it's anyone's guess where that airspace extends to.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a further amplification, they may just tell you 'contact approach on 123.45 and remain clear of the delta'.  So, their own operating procedures will dictate that you do contact approach, but you could run into a similar situation at any airfield where you just have to follow tower instructions.&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="162" LastEditDate="2013-12-31T20:32:52.047" LastActivityDate="2013-12-31T20:32:52.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="511" PostTypeId="2" ParentId="509" CreationDate="2013-12-31T03:58:50.887" Score="2" Body="&lt;p&gt;Since you have your private, the LSA just has to be approved.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgOrders.nsf/0/7a09d53fb0d5325586257885004d9e1b/%24FILE/8130.2G_CHG1_Incorporated.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Order 8130.2G CHG 1&lt;/a&gt; which covers LSA certification:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(5) This aircraft is to be operated under VFR, day only, unless&#xA;  appropriately equipped for night and/or instrument flight in&#xA;  accordance with 14 CFR § 91.205, and when allowed by the&#xA;  manufacturer’s operating instructions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it must be properly equipped (see below) AND &lt;strong&gt;&lt;em&gt;allowed by the manufacturer’s operating instructions.&lt;/em&gt;&lt;/strong&gt;   You will need to check this with each manufacturer to see if they certified it for night flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.3.7.3&quot; rel=&quot;nofollow&quot;&gt;91.205&lt;/a&gt; says day VFR instruments (paragraph b) plus: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Visual flight rules (night). For VFR flight at night, the&#xA;  following instruments and equipment are required:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Instruments and equipment specified in paragraph (b) of this&#xA;  section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Approved position lights.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) An approved aviation red or aviation white anticollision light&#xA;  system on all U.S.-registered civil aircraft. Anticollision light&#xA;  systems initially installed after August 11, 1971, on aircraft for&#xA;  which a type certificate was issued or applied for before August 11,&#xA;  1971, must at least meet the anticollision light standards of part 23,&#xA;  25, 27, or 29 of this chapter, as applicable, that were in effect on&#xA;  August 10, 1971, except that the color may be either aviation red or&#xA;  aviation white. In the event of failure of any light of the&#xA;  anticollision light system, operations with the aircraft may be&#xA;  continued to a stop where repairs or replacement can be made.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) If the aircraft is operated for hire, one electric landing light.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) An adequate source of electrical energy for all installed&#xA;  electrical and radio equipment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) One spare set of fuses, or three spare fuses of each kind&#xA;  required, that are accessible to the pilot in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2013-12-31T03:58:50.887" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="512" PostTypeId="2" ParentId="508" CreationDate="2013-12-31T05:03:25.083" Score="5" Body="&lt;p&gt;PIREPs have no required format other than the identifying information: Location, Time, Altitude, and Aircraft Type.  Other than that, you can call in any number of weather elements as a PIREP.  I often call in nothing but winds aloft and temperature, simply because I know those are more difficult for the weather service to measure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA SkySpotter provides a &lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/Pilot%20Resources/ASI/various%20safety%20pdfs/pirep.pdf&quot;&gt;nice flash card&lt;/a&gt; for recalling the various items, but there's no mnemonic provided.  If you're interested in giving the most complete PIREP possible, I'd suggest following the same format as an ATIS broadcast: wind, visibility, clouds, precip, and then touching on any other relevant information such as temperature or turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, though, &lt;strong&gt;the most important thing about PIREPs is that you give them. The briefer or controller who takes your report will be able to format it properly if you give the elements out of order...they're just happy to get it at all.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2013-12-31T05:03:25.083" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="513" PostTypeId="2" ParentId="500" CreationDate="2013-12-31T12:44:53.747" Score="21" Body="&lt;p&gt;Over the North Atlantic, there are no predefined low-level or high-level airways as there are over the continents. In order for aircraft to get a tailwind for eastbound flights and get out of the wind for westbound flights, Canadian and UK air traffic control set tracks based on the expected wind conditions twice a day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lines you are seeing are called an 'Organized Track System'; is this part of the world, they're called 'NAT' (North Atlantic) Tracks. Five to six roughly-parallel tracks will be defined and move around every day, but they will generally go between whole degrees of latitude and 10° increments of longitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, tonight's (Dec 31/13) track BRAVO ('B') will go from a intersection in the UK called...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ERAKA (at 58°N/10°W) to&lt;br&gt;&#xA;60°N/20°W to&lt;br&gt;&#xA;61°N/30°W to&lt;br&gt;&#xA;61°N/40°W to&lt;br&gt;&#xA;60°N/50°W to&lt;br&gt;&#xA;MOATT (at 58.025°N/59.928°W) to&lt;br&gt;&#xA;LOMTA (at 57.203°N/62.619°W).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/ZqgCgLd.gif&quot; alt=&quot;Depiction of the daily NAT tracks&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="14897" LastEditDate="2018-03-14T18:49:08.810" LastActivityDate="2018-03-14T18:49:08.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="514" PostTypeId="2" ParentId="497" CreationDate="2013-12-31T16:33:17.353" Score="7" Body="&lt;p&gt;So often that to any observer (visual or tactile) it appears continuous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I say this as someone who has 2500 hours operating a transport category airplane. The flight director provides continuous guidance that the autopilot continuously follows. When holding the control column with autopilot on (below 10k feet you hold the controls even with autopilot engaged) you would interpret it as continuous input (the autopilot moves the controls just as if the other pilot were flying). &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-01T18:37:34.003" LastActivityDate="2014-01-01T18:37:34.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="515" PostTypeId="1" AcceptedAnswerId="521" CreationDate="2013-12-31T17:19:43.020" Score="16" ViewCount="3339" Body="&lt;p&gt;So the EGT gauge on the 172 (and other cessna singles?) doesn't have a numerical scale on it, just markings every 25 degrees.  I know that one is supposed to use the EGT for leaning operations (ROP, LOP, what have you), but it's always stymied me that there are no actual numbers on it.  Any reason why this is so?&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="69" LastEditDate="2013-12-31T22:15:48.917" LastActivityDate="2014-01-01T00:30:36.247" Title="Why does the EGT gauge in 172s have no numbers on it?" Tags="&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="516" PostTypeId="1" AcceptedAnswerId="522" CreationDate="2013-12-31T19:18:20.280" Score="30" ViewCount="29392" Body="&lt;p&gt;I'm a student pilot doing all VFR flying and making flight plans for training. I've heard that most people don't file a flight plan for VFR outside of training though, and instead request &quot;flight following&quot; from nearby ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When can I do this in flight? Which ATC can do this for me?&lt;/p&gt;&#xA;" OwnerUserId="13" LastEditorUserId="572" LastEditDate="2016-04-06T06:03:01.637" LastActivityDate="2017-03-13T21:58:51.237" Title="When can I request flight following?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;flight-training&gt;&lt;visual-flight-rules&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="517" PostTypeId="1" AcceptedAnswerId="519" CreationDate="2013-12-31T20:12:37.030" Score="10" ViewCount="1489" Body="&lt;p&gt;Let's say we have a Cessna 150 or some other lightweight two seater and no chance to land with head wind for whatever reason. &#xA;We're trying to land with a constant tailwind of 7 knots. &#xA;I would try to land as close to stall speed as possible to compensate the tailwind. So much for the theory. In reality, the wind is not constant. If I'm close to stall, dying wind will give me trouble. What's a general good approach for such situations? What configuration would you choose? &#xA;If the runway is very long, one can just go faster. But often, runways are rather short. &lt;/p&gt;&#xA;" OwnerUserId="133" LastEditorUserId="69" LastEditDate="2013-12-31T23:16:01.617" LastActivityDate="2020-03-25T11:31:09.857" Title="How to land a sports plane with tailwind?" Tags="&lt;landing&gt;&lt;aircraft-performance&gt;&lt;light-sport-aircraft&gt;" AnswerCount="7" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="518" PostTypeId="2" ParentId="328" CreationDate="2013-12-31T20:13:15.470" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;@Pondlife I suppose it's possible there's an airport somewhere with Class D airspace that REQUIRES you to call approach before you can call the tower, even for VFR flights, but I can't think of any off hand. That would certainly be an unusual situation though: I'd expect a NOTAM about the procedure at the very least.–  voretaq7Dec 25 at 7:05&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Required&lt;/strong&gt; is too strong a word.  Standard Procedure to land VFR at Westchester County Airport, White Plains NY (KHPN) is to contact NY Approach first for sequencing.  However, I have heard both sides of this: a pilot being chewed out for not contacting approach, and sent back away from the Delta space to &quot;get in line&quot;, and also the tower accepting arrivals that just call the tower as the first contact.  It is all based on how busy the Tower is.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;requirement&quot; to call Approach first is not written in any NOTAM I can find.  It is a &quot;local knowledge&quot; thing.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="162" LastEditDate="2013-12-31T20:35:51.183" LastActivityDate="2013-12-31T20:35:51.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="519" PostTypeId="2" ParentId="517" CreationDate="2013-12-31T20:22:30.710" Score="16" Body="&lt;p&gt;Land normally.  Check your POH (Pilot Operating Handbook) first to ensure you have enough runway including the extra needed for a tailwind.  The only thing to watch out for is that winds tend to moderate as you get closer to the ground.  In a headwind landing, the relative wind will decrease, In a tailwind landing the relative wind will increase, so there will be an increased tendency to float way down the runway.  Be on speed for a short field landing technique.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="162" LastEditDate="2013-12-31T20:36:41.233" LastActivityDate="2013-12-31T20:36:41.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="520" PostTypeId="2" ParentId="516" CreationDate="2013-12-31T20:32:22.560" Score="12" Body="&lt;p&gt;You may request flight following anytime, pre-certificate and after.  My CFI required me to request FF while on my student solos - and sometimes ATC is too busy to grant that service, so don't be too surprised if you are turned down.  It is always based on a workload permitted basis by ATC.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another tip - while you are a student pilot, always identify yourself as a student in your flight following request.  ATC does in fact go out of their way to assist students.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowhere is this written down, but I would not request FF for a very short flight.  To me that is just annoying to the controller.  But that may just be me.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="21" LastEditDate="2014-01-01T00:30:43.107" LastActivityDate="2014-01-01T00:30:43.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="521" PostTypeId="2" ParentId="515" CreationDate="2013-12-31T20:38:49.570" Score="18" Body="&lt;p&gt;The simple EGT gauges do not have numerical scales because you never lean to a temperature.  You find the peak temperature, set the movable red needle to that temperature, and then lean to x degrees lean (or enrichen to x degrees) of peak temperature.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Set the peak temperature at full throttle, full rich at a sea level airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This system eliminates the concerns of calibration: Is the gauge calibrated, did the mechanic install the probe in exactly the right spot, etc. etc.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="21" LastEditDate="2014-01-01T00:30:36.247" LastActivityDate="2014-01-01T00:30:36.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="522" PostTypeId="2" ParentId="516" CreationDate="2013-12-31T21:01:37.517" Score="25" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/520/64&quot;&gt;SkipMiller said&lt;/a&gt;, you can basically request flight following at any time and any certificate level - student, sport pilot, private pilot - the service is available to anyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We're told that FF is &quot;workload permitting&quot;.&lt;br&gt;&#xA;I used to think that meant they'd give you services when they can.   But I was wrong about that. Instead, once they accept you, you're in the system, and get full services.   If they get too busy, they'll tell you and kick you out of the system.  (&lt;em&gt;&quot;Radar Services Terminated; Squawk VFR&quot;&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FF depends on radar services.   When flying rather low and near mountains, its easy for them to lose you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for when you should request it:  You &lt;em&gt;can&lt;/em&gt; request it at anytime.&lt;br&gt;&#xA;Personally, I wouldn't be in a hurry to request it as soon as you depart.   Wait until you're established on course, in a cruise-attitude (instead of a climb), and everything is settled and running smoothly.  Then know your position, and how you're going to report it.  Know where you're going (both by name and ICAO identifier), and try to anticipate any questions they might ask.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look for the Center/Approach/Depature where you are  (look in your AF/D for an airport close to you), and call up with:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You&lt;/strong&gt;:   &lt;em&gt;&quot;Seattle Center; November 12345: VFR, with request&quot;&lt;/em&gt;&lt;br&gt;&#xA;&lt;em&gt;translation:&lt;/em&gt;  Calling Seattle Center, this is N12345.  I'm VFR (so you haven't heard from me before... don't be surprised!), and I have a request.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Center&lt;/strong&gt;:  &lt;em&gt;&quot;November 12345: Say request.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You&lt;/strong&gt;:  &lt;em&gt;&quot;November 12345 is SkyHawk, 10 mi. South of Harvey Field, 4,500 feet.  Request VFR Flight Following to Friday Harbor&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;translation&lt;/em&gt;: I'm a Cessna Skyhawk, my location and altitude will help you find me.  I'm asking for FF to this other airport.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Center&lt;/strong&gt;:  &lt;em&gt;&quot;N345: Squawk 4532 and Ident.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You&lt;/strong&gt;: (Set your transponder to 4532, press the Identify Button), and say &lt;em&gt;&quot;4532 and Ident, N345&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Center&lt;/strong&gt;:  &lt;em&gt;&quot;N345: Radar Contact, 11 mi. south of Sierra Four Tree, at 4,500.  Traffic at your 1o'clock, 5 mi. North Bound, Altitude indicates 3,000.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;translation&lt;/em&gt;:  I found you on my radar scope, and am describing the position I see you. (If you disagree, speak up!).  You have traffic ahead and slightly to your right.  Their transponder indicates 3,000 feet, but I cannot independently verify that.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-01-01T23:43:30.057" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="523" PostTypeId="2" ParentId="426" CreationDate="2013-12-31T21:04:12.357" Score="11" Body="&lt;p&gt;There is no official FAA guidance on taxi speed.  There is an urban legend around that the speed limit is &quot;no faster than a man can walk&quot; and although every airplane exceeds that pace today, the origin of that &quot;no faster than a man can walk&quot; goes back to the early days of aviation.  The very early planes had no brakes and no steerable wheels!  They required wing walkers to stop the planes and to guide them around corners.  Yes it was possible for the pilot to raise the tailskid off the ground and rudder his way around a corner, but in close quarters this would add too much speed so that wing walkers were the solution.  Why the rule of &quot;no faster than...&quot;  Don't leave your steering gear (the wing walkers) behind!  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="11" LastEditDate="2014-01-10T17:51:45.350" LastActivityDate="2014-01-10T17:51:45.350" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="525" PostTypeId="2" ParentId="517" CreationDate="2013-12-31T23:15:27.677" Score="10" Body="&lt;p&gt;You should never try to land &quot;as close to stall speed as possible&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Manufacturers have a recommended approach and landing speed for a reason.  It is a compromise between a safe margin over stall speed, aircraft controllability, and landing distance.  You should use their experience with the airplane by following their recommendations.  Sometimes they have adjustments because of the wind, sometimes they don't because they don't feel that they are necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Follow the recommended procedures and the POH/AFM will tell you the performance that you can expect. Do anything else and you are flying in an uncharted area (literally) and can find yourself in trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, make sure that you check to see if there is a limitation for a maximum tailwind component for the specific airplane.  If you exceed this, you can run into controlability issues or exceed the maximum speed that the tire is rated for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, just fly by the book and be aware that you will use more runway so be sure to check the operating handbook to stay safe. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-01T17:03:55.933" LastActivityDate="2014-01-01T17:03:55.933" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="526" PostTypeId="2" ParentId="508" CreationDate="2014-01-01T00:38:37.330" Score="2" Body="&lt;p&gt;The technique I have is to just call up ATC and ask if they've got time for &amp;quot;a quick PIREP&amp;quot;. If I'm giving a PIREP I'm almost always either on flight following or IFR, in which case they already have my aircraft type; from there, I give a brief report with the items I want to provide. It usually looks something like this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Cessna 321AB:&lt;/strong&gt; Seattle Center, Cessna 321AB... I've got a PIREP for you if you have a moment.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;ZSE:&lt;/strong&gt; Cessna 1AB, go ahead.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Cessna 321AB:&lt;/strong&gt; Ok... over CLM at 7500, five minutes ago, the winds aloft were 280 at 20, temperature 39, clear below.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;ZSE:&lt;/strong&gt; Cessna 1AB, got it. Thank you.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I never worry about order, and I've never gotten yelled at by ATC or Flight Service.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As an aside, if it's crazy windy aloft with lots of changes per altitude, I'll give ATC winds almost always. If there's icing conditions or below-freezing temps, I will &lt;em&gt;always&lt;/em&gt; provide a PIREP. They don't get into the system often enough and if you treat it casually and provide just the relevant info for the day (if it's clear, don't tell them this) you're doing everybody a great service.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-01T00:38:37.330" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="527" PostTypeId="2" ParentId="497" CreationDate="2014-01-01T05:32:36.073" Score="0" Body="&lt;p&gt;Well I remember doing a night flight from Japan to Uk over russia&#xA;in a JAl 747 and a perfect view of the wing, and night start et all..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And one thing I noticed was that the inner airelon&#xA;moved once every four seconds as in a change, next, next, next&#xA;no predictable will be up or down or whatever way..&#xA;just a maybe 10cm movement or less, continuously..&#xA;was a joy to watch and some PID controller..&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/PID_controller&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/PID_controller&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="42" LastActivityDate="2014-01-01T05:32:36.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="528" PostTypeId="1" AcceptedAnswerId="529" CreationDate="2014-01-01T05:55:24.107" Score="15" ViewCount="5323" Body="&lt;p&gt;Tonight's fireworks got me wondering:  With all of the firework displays happening at the same time, how do they keep aircraft away from them?  Is there any risk of collision or blinding the pilots?  Is there anything that pilots need to do differently when fireworks are in the area?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-02-14T19:01:32.103" Title="Are fireworks a hazard to aircraft?" Tags="&lt;safety&gt;&lt;airspace&gt;" AnswerCount="3" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="529" PostTypeId="2" ParentId="528" CreationDate="2014-01-01T15:39:53.440" Score="8" Body="&lt;p&gt;In &lt;a href=&quot;/questions/tagged/canada&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;canada&amp;#39;&quot; rel=&quot;tag&quot;&gt;canada&lt;/a&gt; and I assume in a similar way in the United States, fireworks are treated like any other obstacle such as a communication tower, building, or crane. The location and elevation of the firework activity is assessed for impacts to any instrument procedures, airways, minimum altitude areas, etc. and NOTAM to temporarily amend affected procedures will be issued prior to the activity to advertise the changes and their effective periods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, this doesn't address the VFR side of things. Operating near fireworks is essentially the same &lt;em&gt;see and be seen&lt;/em&gt; idea. NOTAM get issued here all the time for the fireworks activity themselves and they would include a radius from the centre point. Simply avoiding the area is usually sufficient.&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2014-01-01T15:39:53.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="531" PostTypeId="2" ParentId="498" CreationDate="2014-01-01T19:58:04.543" Score="6" Body="&lt;p&gt;Most sophisticated autopilot systems used in modern airliners are integral parts of a larger Flight Management System (FMS). FMS systems include multiple independant computers communicating over one or more common data busses which allow for expandability and upgradability. Examples of the various 'customer facing' independent parts for the B-737, each it's own computer, are one or more Control Display Units (CDUs), Mode Control Panel (MCP), and autopilot logic computers. There are also multiple independent and redundant computers for the various air data and navigation position systems that feed into the FMS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each computer is optimized for it's specific task so it is very difficult to answer your question. Characteristically, there is just enough computing horsepower to get the job done and nothing more (and occasionally just a bit less...).&lt;/p&gt;&#xA;" OwnerUserId="249" LastActivityDate="2014-01-01T19:58:04.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="532" PostTypeId="2" ParentId="528" CreationDate="2014-01-02T02:56:12.560" Score="3" Body="&lt;p&gt;In addition to the previous answer, there are often TFRs (Temporary Flight Restrictions) around the areas of organized fireworks displays- before you fly you're responsible for knowing where these locations are and not flying into that airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as avoiding the stray bottle rocket, hopefully you're high enough in cruise and lucky enough in takeoff/landing to avoid these hazards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as blinding, the fireworks can take away your night vision if you're close enough but I don't think it would blind. At least it has never happened to me.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-01-02T02:56:12.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="533" PostTypeId="1" AcceptedAnswerId="536" CreationDate="2014-01-02T12:19:39.650" Score="8" ViewCount="8076" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=224e5eff75b49b3d4b23f02c9958f369&amp;amp;node=14:3.0.1.1.11.6&amp;amp;rgn=div6&quot;&gt;14 CFR 135, Subpart F&lt;/a&gt; contains the rest requirements for Part 135 operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest requirement for 1 and 2 pilot unscheduled crews (typical) comes from:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;135.267(d)&lt;/strong&gt;&lt;br&gt;&#xA;  Each assignment under paragraph (b) of this section must provide for at least 10 consecutive hours of rest during the 24-hour&#xA;  period that precedes the planned completion time of the assignment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does the FAA consider rest and what actions by the company will interrupt the required rest?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2020-01-27T14:32:44.050" LastActivityDate="2020-01-27T14:32:44.050" Title="What is the legal interpretation of rest for FAA Part 135 operations?" Tags="&lt;faa-regulations&gt;&lt;far-135&gt;&lt;pilot-fatigue&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="534" PostTypeId="1" AcceptedAnswerId="610" CreationDate="2014-01-02T14:48:21.383" Score="5" ViewCount="576" Body="&lt;p&gt;I understand you're required to have an AZF-license, on top of a BZF-license to do IFR radio transmissions in Germany; I also figure the test is similar to the BZF license with a written and an oral part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's a typical sequence of radio calls in the oral test? Are there any particular gotchas one should be aware of? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read through a list of phrases (out of something called NfL), so I'm vaguely familiar with the differences from US phraseology, but I got from the BZF test there are other differences, like you tend to get a question &quot;Are you ready to copy&quot;, rather than the &quot;advise ready to copy&quot; I'm used to.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="572" LastEditDate="2015-02-19T10:04:22.487" LastActivityDate="2015-02-19T10:04:22.487" Title="What does the German AZF radio license test comprise of in the oral examination?" Tags="&lt;radio-communications&gt;&lt;germany&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="535" PostTypeId="2" ParentId="51" CreationDate="2014-01-02T17:03:05.373" Score="9" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Republic_XF-84H&quot;&gt;Republic XF-84H &quot;Thunderscreech&quot;&lt;/a&gt; was a USAF jet fighter modified with a turboshaft engine and a propeller designed to operate at supersonic blade speeds. It first flew in 1955, and the result was &lt;a href=&quot;http://www.youtube.com/watch?v=YItexQxJS9U&quot;&gt;a noise that was literally deafening&lt;/a&gt;. During ground engine runs, &quot;the prototypes could reportedly be heard 25 miles (40 km) away.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas there may be some advantages of a supersonic propeller, the side effects (the noise) prohibit the use of a supersonic propeller even for military applications, let alone civilian ones.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question proposes a helicopter with supersonic blades, at least on the blade advancing side of the helicopter.  There is no research that I know of that would indicate a supersonic blade on the main rotor of a helicopter will act differently than the supersonic blade on a propeller on an airplane.  The assumption is therefore that the blades would experience a very significant increase in drag, and would also produce a very significant amount of noise.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-03-07T20:37:39.050" LastActivityDate="2014-03-07T20:37:39.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="536" PostTypeId="2" ParentId="533" CreationDate="2014-01-02T17:06:17.677" Score="6" Body="&lt;p&gt;The 10 hours of rest need to be uninterrupted, planned, and not spent on call. Essentially, the pilots need to have 10 hours in which they are not obligated to do &lt;strong&gt;any work for the company&lt;/strong&gt; &lt;em&gt;at all&lt;/em&gt;.  Note that it does not mean &quot;10 hours of sleep&quot;, and it is up to the pilot what they do with their time off.  (They can even technically fly for another 135 operator during that time, but they run the risk of being &quot;careless and reckless&quot; if they aren't well rested.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NATA has &lt;a href=&quot;http://www.nata.aero/data/files/abj/FAA_legal_interpretations_abj.pdf&quot; rel=&quot;nofollow&quot;&gt;an article about some of the FAA's legal interpretations (pdf)&lt;/a&gt; that's pretty interesting and relatively recent (2011). Their paraphrase of the FAA's varying interpretations is this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the FAA has said that for a “rest period” to be legal it must be: 1) continuous, 2) determined prospectively (i.e. known in advance) and 3) free from all restraint from the certificate holder, including freedom from work or freedom from the present responsibility for work should the occasion arise.  Being on call is specifically mentioned as not rest.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is an interpretation that is repeated throughout a lot of articles and forum discussions. It's also often pointed out that many (most?) 135 carriers blatantly ignore these rules, as most charter operations require pilots to be on call.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;For example&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You arrive at 19:00, and are done with paperwork / postflight / etc by 19:30 and leave the airport. The moment that you leave the airport is the beginning of your rest period; it will need to last 10 uninterrupted hours, which means until at least 0530 the next morning (1930 to 0530) to mean anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get a call from dispatch at 21:00 telling you about a flight that might take place in the morning and that you must be available for a call at 05:00 just in case - your rest ends at 05:00. Because your rest period ended 30 minutes early (when you were required to be available), you did not get the 10 hours of rest and can't take a flight without violating 135.267(d).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Another caveat:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are no explicit limits on duty time (the exception being 135.267(c) involving a &quot;regularly assigned duty period of no more than 14 hours&quot; which doesn't apply to most 135 operators).  The limit is on &lt;strong&gt;&lt;em&gt;planned flying&lt;/em&gt;&lt;/strong&gt; conducted under 135. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you &lt;strong&gt;plan&lt;/strong&gt; on parking the airplane when you can show 10 hours of rest in the previous 24 hours (which is why some people incorrectly assume that you are limited to 14 hours of duty: 24 - 10 = 14!), you can be kept on duty afterwards.  You can even fly under Part 91 for the company.  You can clean the airplane, or do office work.  While none of that is rest and it is still duty, it is legal unless you get in the airplane to fly under Part 135 without getting the required rest.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2014-01-03T02:01:08.793" LastActivityDate="2014-01-03T02:01:08.793" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="537" PostTypeId="1" AcceptedAnswerId="548" CreationDate="2014-01-02T17:26:54.253" Score="48" ViewCount="12584" Body="&lt;p&gt;&lt;em&gt;(background: low-hour, low-experience, private pilot.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've got an issue regarding talking to air traffic controllers, especially when I think they may have messed up, yet still giving them the respect they deserve as hard working professionals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One common scenario is when I'm ready to go, along with multiple other planes, all coming from various taxiways.   I know the tower tries hard to clear us each more-or-less in the order we've called up.   But when one plane feels they've been badly skipped, or possibly forgotten, it can get awkward.&lt;p&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard a pilot say (very politely, and with good cause):&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;&quot;Tower; Arrow-23: Did you forget about me?&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;only to have the tower come back with a snappy and frustrated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;&quot;I'm doing the best I can.  I'll get you all out of here as fast as I can.  Just wait your turn!&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Obviously, that didn't go very well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, I've tried to be patient for awhile, only to learn that the Tower really did overlook me, and sequenced several planes out in front of me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground, its wasted fuel, HOBBS, and time.&lt;br&gt;&#xA;But in the air, it can be more significant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes I've had tower miss actually clearing me to land.&lt;br&gt;If they're trying to sequence me in, I stay on an extended the downwind leg for a long time, waiting to be cleared before turning base.  But if they really did get busy and overlook me, I can end up well out of position.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I call and ask, sometimes they'll get a little testy with me if they are just busy.&lt;br&gt;&#xA;If I stay silent, I might've been skipped/forgotten, and end up flying downwind for a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Whats the most appropriate, friendly, and polite way to check in and make sure nothing got missed, without sounding accusatory?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="69" LastEditDate="2014-01-13T01:51:49.680" LastActivityDate="2014-10-19T01:07:43.550" Title="How can I politely remind ATC that I'm waiting for instructions or clearance?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="538" PostTypeId="2" ParentId="537" CreationDate="2014-01-02T17:52:30.887" Score="27" Body="&lt;p&gt;What I usually do is repeat the last clearance or instruction. That way you give ATC the impression that you're not impatient but just reporting your progress. If they really forgot you they will quickly rectify the situation. If they didn't and it was intentional, they won't feel as if they are being accused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Examples:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;When holding at a holding point:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tower, N1234, holding RWY 27&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;When still on extended downwind, being &quot;forgotten&quot;:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tower, N1234, continuing downwind&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;When waiting for a landing clearance during approach:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tower, N1234, continuing approach&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;And if they still don't clear you when you're already below 200ft or over the threshold:&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, VERY short final&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-02T18:03:06.837" LastActivityDate="2014-01-02T18:03:06.837" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="539" PostTypeId="1" AcceptedAnswerId="549" CreationDate="2014-01-02T18:45:41.837" Score="1" ViewCount="1259" Body="&lt;p&gt;I am interested in real-life experiences to do with using LiFePO4 batteries in light aircraft and motorized gliders compared to standard PbA ones. LiFePO4 seem to be a very attractive alternative to the good ole lead ballast with regard to weight/size and useable capacity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Points of interest include amongst others:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Operation safety&lt;/li&gt;&#xA;&lt;li&gt;Handling (e.g. with regard to charging)&lt;/li&gt;&#xA;&lt;li&gt;Robustness (electric, mechanical)&lt;/li&gt;&#xA;&lt;li&gt;Compatibility (electric, fittings etc.)&lt;/li&gt;&#xA;&lt;li&gt;Cost vs. Benefit assessment&lt;/li&gt;&#xA;&lt;li&gt;Temperature influence&lt;/li&gt;&#xA;&lt;li&gt;Life expectancy&lt;/li&gt;&#xA;&lt;li&gt;Technical / legal admission (e.g. insurance-related)&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="95" LastEditorUserId="64" LastEditDate="2014-03-14T15:38:00.430" LastActivityDate="2014-03-14T15:38:00.430" Title="Experiences with LiFePO4 starter batteries in light aircraft or motorized gliders?" Tags="&lt;piston-engine&gt;&lt;light-sport-aircraft&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-01-07T15:56:50.917" ContentLicense="CC BY-SA 3.0" />
  <row Id="540" PostTypeId="2" ParentId="184" CreationDate="2014-01-02T19:14:24.697" Score="22" Body="&lt;p&gt;Outlandings are a regular occurrence when gliding cross-country. During competitions with tens of participants, it is not uncommon for a few gliders to land out each day. For this reason, in the UK at least, glider pilots are taught how to land out, and think about this eventuality on every flight. Many will have experienced a landout with an instructor before going solo, and practice approaches to fields are a requirement of gaining the cross-country endorsement (part of the UK syllabus).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, there isn't a lot to do after your beautifully-executed landing. In common law countries (including the US and the UK) on private land you are trespassing, and the landowner can ask you to leave. Of course this is already your intention, but it's complicated by the expensive machine you have just deposited there. Any damage you cause (or caused, on your way in) is your liability. Your aircraft is still yours, and the landowner cannot prevent you from removing it. If he tries, he is responsible for keeping it safe and will be liable for any damage. He can charge a reasonable fee for his time and the unauthorised use of his land, but often will not. Some landowners object to professional balloon companies charging large sums for taking parties of champagne drinkers into their fields and want a cut of the profits. In this case, remind him that you are a private individual and that you landed there without intending to in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So your plan should basically be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Make the aircraft safe.&lt;/li&gt;&#xA;&lt;li&gt;Inform whoever you were most recently in contact with that you have landed safely (ATC, or your fellow travellers on common frequencies).&lt;/li&gt;&#xA;&lt;li&gt;Find the landowner, explain that you didn't mean to land there, that it was an emergency and that you intend to retrieve your property as soon as possible. Obtain permission for vehicles to enter his land.&lt;/li&gt;&#xA;&lt;li&gt;Contact your friends to bring the trailer, derig the aircraft and drive home.&lt;/li&gt;&#xA;&lt;li&gt;Buy dinner for your friends.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you have approached over built-up areas or roads, someone will probably have seen you and is likely to call the emergency services on your behalf. In the UK, NATS (the National Air Traffic Service) coordinates with the police in cases of aircraft outlandings. You should call their distress and diversion (D&amp;amp;D) cell to inform them of the situation, even if there is no damage or injury.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the landowner tries to impound your aircraft or becomes aggressive, call the police. There have been cases where landowners have caused damage to aircraft and recourse was only possible because of police attendance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have caused any damage, try to come to an agreement on the cost. Often, young crops are not damaged by landing aircraft, and if you have landed in a long crop you are probably not capable of discussing compensation. Ploughed fields and grass fields are more likely to have damaged your aircraft than the other way round.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outlandings are not the end of the world. If it worries you, why not hop along to your local gliding club and take a flight. Most instructors will be more than happy to show you round the local fields!&lt;/p&gt;&#xA;" OwnerUserId="306" LastActivityDate="2014-01-02T19:14:24.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="544" PostTypeId="1" AcceptedAnswerId="2782" CreationDate="2014-01-02T22:23:51.390" Score="9" ViewCount="5360" Body="&lt;p&gt;I am familiar with the NACA 4-digit and 5-digit airfoil design system where airfoils, but I was wondering if anyone had some good reference material or software for designing a completely custom airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I understand, many new aircraft use completely custom non-NACA airfoils, sometimes several different airfoils over the wingspan. I am curious about how the design process goes from specifications of the airflow (incidence angle, perhaps the sweep of the wing, air speed, density, reynolds number etc) to a new custom airfoil?&lt;/p&gt;&#xA;" OwnerUserId="206" LastEditorUserId="65" LastEditDate="2015-04-15T17:40:14.257" LastActivityDate="2015-04-15T17:40:14.257" Title="How to go about designing a custom airfoil?" Tags="&lt;aircraft-design&gt;&lt;airfoil&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="545" PostTypeId="2" ParentId="474" CreationDate="2014-01-02T22:54:19.940" Score="2" Body="&lt;p&gt;From what I understand, you want stability and good crash-worthiness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For stability, what you want is to drop the CG of the middle section below the plane of the propellers. The lower the CG of the middle part, the more stable your craft will be. Additionally, you would want to lower the control sensitivity of the pitch, roll, and yaw axes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;voretaq7 did a great job covering crash worthiness in my opinion, in addition to protecting the propellers from impact, properly designed shrouds can actually improve the performance of your aircraft as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trick to any crash is to dissipate as much energy as possible. One way, as vortaq mentioned is by designing the copter to break apart. Another way is to absorb the fall with purpose-built mechanisms that absorb  energy. These mechanisms are generally refered to as suspensions in cars and motorcycles. A suspension consists of a spring mechanism, and a dampening mechanism. The simple description is that you need a spring to absorb the impact, and a dampener to keep it from bouncing back up. Here are some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flat carbon fiber rods - good spring force, poor dampening, light weight.&#xA;Shocks (like from RC cars) - limited spring travel, heavy, good dampening.&#xA;Foam - properties depend on the type of foam, but generally has good dampening.&lt;/p&gt;&#xA;" OwnerUserId="206" LastActivityDate="2014-01-02T22:54:19.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="546" PostTypeId="2" ParentId="544" CreationDate="2014-01-02T22:59:46.570" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot;&gt;XFOIL&lt;/a&gt; is a piece of free software that appears to be under at least semi-active development (latest update this year, nothing for two years prior). I've never used it and know nothing about it; this was merely the product of a google search for &quot;&lt;a href=&quot;https://www.google.com/search?rls=en&amp;amp;q=airfoil%20design&amp;amp;ie=UTF-8&amp;amp;oe=UTF-8&quot;&gt;airfoil design&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XPlane has a feature called &lt;a href=&quot;http://wiki.x-plane.com/Supplement%3a_Airfoil-Maker&quot;&gt;Airfoil Maker&lt;/a&gt; that I messed with once. It hurt my brain, but not necessarily because it was bad - it's just complicated stuff. The fun part about XPlane for design is that you also get to design or modify aircraft and fly them to see how the changes affect performance, handling, or other characteristics.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-02T22:59:46.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="547" PostTypeId="2" ParentId="497" CreationDate="2014-01-02T23:39:48.240" Score="0" Body="&lt;p&gt;It depends on the manufacturer and model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although it's possible to create an autopilot that updates real-time/continuously, not all autopilots are actually designed to do so. Some autopilots (particularly older ones) updated once a minute, sometimes even slower. There are several logical reasons to do this - one is to conserve power, the other is to lower cost - slower computers used to be significantly cheaper than ones that were fast enough to compute real time. It's also simply unnecessary to continuously update the control surfaces. So say you drift a couple hundred feet off course because the wind changed, the autopilot will correct within the next minute, and you'll end up continuing on merrily and you (as a pilot or passenger) would not have noticed. The only time you need continuous updates to the control surfaces and engine speed, is during landing, and if I'm not mistaken, there's isn't a fully autonomously landing autopilot on the market (for civilian planes anyhow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, an autopilot that continuously updates the control surfaces may end up creating a jerky flight because it's constantly auto-correcting for wind gusts and changes in wind direction.&lt;/p&gt;&#xA;" OwnerUserId="206" LastActivityDate="2014-01-02T23:39:48.240" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="548" PostTypeId="2" ParentId="537" CreationDate="2014-01-02T23:51:36.663" Score="57" Body="&lt;p&gt;There's lots of advice I can give you here, but the answer is really that the degree of communication tower wants/needs depends on your local tower (and to some degree the individual controllers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the most universal piece of advice I can give you is to think like a controller.  Listen to the frequency and get a picture of what's going on in the airspace before you call them, and when you get good at it you'll also get good at knowing what kind of a situation you're flying in to (Is the airspace empty, or are there 4 planes in the pattern for landings, 3 in the opposite downwind shooting touch-and-gos, and a jet arrival on an instrument approach that just got dumped on the tower inside 7 miles barreling in &amp;amp; messing everything up?) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also remember that from a controller's perspective of priorities (&quot;Safe, Orderly, Expedient&quot;) speed doesn't count for much when compared to the other two requirements of the job (and aircraft on the ground are &lt;em&gt;inherently&lt;/em&gt; Safe and Orderly unless they do something stupid like go charging across the hold-short line). Unfortunately for us pilots delaying the plane on the ground (that isn't moving, and is thus unlikely to hit anything) is generally preferable to trying to maneuver and delay the ones in the air (that can't stop moving unless they hit something, which is generally considered to be a Bad Thing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a masters class in &quot;thinking like a controller&quot; call your local tower and ask to arrange a tour / shadow a controller for an afternoon. Spending the day in the cab is a great way to get an appreciation for how crazy things can get up there.&lt;br&gt;&#xA;You can usually Google up the phone number, or call Flight Service or your local FSDO and ask. For most towers it's relatively easy to set up a tour (they'll ask for a driver's license and possibly FAA certificate number to do a background check and make sure you're not &lt;em&gt;completely&lt;/em&gt; insane).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The rest of this post is just my personal view on getting along with controllers based on doing most of my training &amp;amp; flying at a pretty busy towered field (According to &lt;a href=&quot;http://aspm.faa.gov/opsnet/sys/Tower.asp&quot;&gt;the FAA's ATADS &quot;Tower Operations&quot; ranking&lt;/a&gt; KFRG was #42 in 2013). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;On The Ground&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;When you're ready to go call tower and tell them - Something like &lt;code&gt;Tower, Cessna 12345 number one runway 32, ready to go.&lt;/code&gt; is usually plenty (if your airport is configured such that there may be some question as to &lt;em&gt;where&lt;/em&gt; you are specify which taxiway/intersection you're at).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After you call the tower and tell them you're ready my experience is you're not likely to be forgotten about. You may be sitting there for a while (my personal record is about a half hour at the hold-short line), but the tower can &lt;em&gt;usually&lt;/em&gt; see you sitting there at the runway end waiting. They want to get rid of you, they just need a hole big enough that they can get you onto the runway and airborne without creating any conflicts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you &lt;em&gt;are&lt;/em&gt; forgotten (it does happen sometimes - you'll see other aircraft being cleared for takeoff who called the tower to report ready after you, or the controller changes, or you've been listening and are pretty sure the airspace is clear but you're still waiting) a polite call to remind the tower you're ready to go isn't out of order. Just don't be &lt;em&gt;That Guy&lt;/em&gt; calling every couple of minutes, and if the controller gets a little snippy just be the better person and shrug it off.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;In The Air&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;In the air is a slightly different story.  Sometimes it can take me 3 or 4 calls to get tower to even acknowledge my existence on busy days (again, you don't want to be &lt;em&gt;That Guy&lt;/em&gt; calling the tower every 10 seconds - you should have a picture of what's going on in the airspace, and if the controller is busy you may have to circle outside their airspace for a while).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you've made contact a good controller will communicate with you and tell you what they need you to do and where they want you to report, where to turn base, or who they want you to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you feel like you've been forgotten a well-timed position report is usually the best way to remind the tower you exist (and as a bonus it helps everyone else with their mental picture of the airspace too).&lt;br&gt;&#xA;For example on an extended downwind for runway 01 at Republic you'll pass Sunrise Highway (a pretty easily identified road, and if you miss it you'll spot the train tracks right after it), the inner shore of Long Island, and the outer shore of the barrier beaches. Reporting each of those points while waiting for tower to call your base generally works (if they genuinely forgot about you they'll usually have an &quot;Oh S%$^!&quot; moment when you call them over the outer shoreline and turn you in for a 7-mile final).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One exception to my position reports technique is landing clearance -- I generally do &lt;em&gt;something&lt;/em&gt; to remind myself if I've been cleared to land (fold a chart, turn my kneeboard, etc.) and if I don't recall being cleared I'll call somewhere between 500 feet and the threshold with something line &lt;code&gt;Tower, confirm N12345 landing clearance?&lt;/code&gt; (Where depends on the conditions of the day - sometimes they crank out departures pretty tight &amp;amp; if someone's rolling waiting until they're airborne is usually a good idea).&lt;br&gt;&#xA;Sometimes they cleared me and I missed it.&lt;br&gt;&#xA;Sometimes they didn't clear me and they do.&lt;br&gt;&#xA;Sometimes they have an &quot;Oh S%$^!&quot; moment (they forgot about me, have a conflict, and I go around).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of those situations are generally preferable to landing on a runway someone else may have been told they can use.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-03T16:23:41.447" LastActivityDate="2014-01-03T16:23:41.447" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="549" PostTypeId="2" ParentId="539" CreationDate="2014-01-03T01:56:26.000" Score="3" Body="&lt;p&gt;Well, I'll start by saying that (at least to my knowledge, in the USA) there are &lt;em&gt;no&lt;/em&gt; certificated/PMA'd/TSO'd LiFePO&lt;sub&gt;4&lt;/sub&gt; batteries currently available on the market for use in certificated airframes.&lt;br&gt;&#xA;That means if you're using a type-certificated aircraft (or an LSA that didn't ship with one originally and for which there is no manufacturer-approved procedure to install one) you're basically out of luck unless you can convince your local FSDO to approve it as a one-off modification to your airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there are some people using them in homebuilts. &lt;a href=&quot;http://www.n416.com/LiFePO4.html&quot; rel=&quot;nofollow&quot;&gt;This guy, for example&lt;/a&gt; has used one on his SQ2000 to replace the starter/cranking battery, and &lt;a href=&quot;http://www.aerolithium.com/faq.html&quot; rel=&quot;nofollow&quot;&gt;there's a company called AeroLithium that sells aviation lithium batteries (albeit uncertified)&lt;/a&gt; which some folks seem to be using in (experimental) Carbon Cubs with a good deal of success.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As to the batteries themselves, my aircraft is certificated, I've got no desire to take it experimental, and my relationship with the local FSDO is not one where I could just walk in and say &quot;I want to stick one of these in my plane. Sign off on the 337 form KTHXBYE!&quot; so this is all just theoretical:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Operationally, LiFePO&lt;sub&gt;4&lt;/sub&gt; is a &lt;em&gt;relatively safe&lt;/em&gt; chemistry.&lt;br&gt;&#xA;Unlike conventional lead-acid batteries it's not going to spit sulfuric acid on your plane during charging or hard maneuvering.  Unlike other Lithium-based chemistries (say Lithium-Cobalt of Dreamliner fire fame) it's not as prone to blowing up or catching fire if short-circuited or otherwise abused (though puncturing it is still a Bad Thing).&lt;br&gt;&#xA;Note however that as LiFePO&lt;sub&gt;4&lt;/sub&gt; is a lithium based chemistry water may not be the best extinguishing agent for a ruptured/burning battery. One of the potential decomposition products of a burning or ruptured LiFePO&lt;sub&gt;4&lt;/sub&gt; battery in the presence of water is Hydrogen Fluoride (HF), which is rather nasty stuff.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Handling and Charging is generally normal - as in you can connect it to your aircraft charging system with appropriately-rated breakers/fuses.&lt;br&gt;&#xA;Checking cell balance is recommended periodically, but without adequate information on the use of these batteries in aircraft we can't say what &quot;periodically&quot; means -- Every 10 hours? Every 50? Annually? (If installing one of these in a homebuilt I'd start with every 10 hours and work from there).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Robustness should be superior to lead-acid batteries in all respects (mechanical and electrical).&lt;br&gt;&#xA;For use in an aircraft a sturdy housing around the cells would be a Must Have to prevent the battery from being ruptured in the event of an incident, but that could be produced reasonably.&lt;br&gt;&#xA;Electrically LiFePO&lt;sub&gt;4&lt;/sub&gt; has a lower self-discharge rate, better tolerance for overcharging, and better (flatter) discharge curves - all Good Things.  It is also stable over a wide range of temperatures, and at least theoretically will outlast lead-acid batteries on a charge/discharge cycle and calendar-year basis (though again, without real-world utilization data we can't really say anything for sure here).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cost-Benefit is hard to qualify.&lt;br&gt;&#xA;LiFePO&lt;sub&gt;4&lt;/sub&gt; batteries can be had cheaper than &quot;aircraft batteries&quot;, largely owing to the fact that they're not approved for use in certificated aircraft.&lt;br&gt;&#xA;Because of their higher energy density they're also substantially lighter for the same amp-hour capacity, which is always attractive when we're talking about aircraft applications.&lt;br&gt;&#xA;All of those benefits aren't worth a warm bucket of spit &lt;em&gt;to me&lt;/em&gt; because I can't install one in my airplane (though I'd certainly consider it seriously if it were a viable option).  If you &lt;em&gt;can&lt;/em&gt; install one in your airplane as a replacement for your main battery it may well be worth considering.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-03T01:56:26.000" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="550" PostTypeId="1" AcceptedAnswerId="554" CreationDate="2014-01-03T03:01:17.233" Score="12" ViewCount="13361" Body="&lt;p&gt;What is an ICAO pilot license?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen it as a job requirement before, does my FAA ATP count?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-09-02T09:13:04.010" LastActivityDate="2016-09-02T09:13:04.010" Title="Does an FAA pilot certificate qualify as an ICAO pilot licence?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="551" PostTypeId="5" CreationDate="2014-01-03T04:55:01.367" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Light-sport_aircraft&quot; rel=&quot;nofollow&quot;&gt;Light Sport aircraft&lt;/a&gt; are simple aircraft which may be operated by a pilot holding a Sport Pilot certificate or higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific regulations governing what constitutes a &quot;Light Sport Aircraft&quot; vary slightly from jurisdiction to jurisdiction.  In the United States some of the requirements for an airplane (land) to qualify as a Light Sport aircraft are as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A maximum takeoff weight of not more than 1,320 pounds (600 kilograms)  &lt;/li&gt;&#xA;&lt;li&gt;A maximum airspeed in level flight with maximum continuous power (V&lt;sub&gt;H&lt;/sub&gt;) of not more than 120 knots CAS under standard atmospheric conditions at sea level.&lt;/li&gt;&#xA;&lt;li&gt;A maximum stalling speed of not more than 45 knots CAS at the aircraft's maximum certificated takeoff weight.&lt;/li&gt;&#xA;&lt;li&gt;A maximum seating capacity of two persons, including the pilot.&lt;/li&gt;&#xA;&lt;li&gt;A single, reciprocating engine&lt;/li&gt;&#xA;&lt;li&gt;A fixed-pitch propeller or ground-adjustable propeller&lt;/li&gt;&#xA;&lt;li&gt;A nonpressurized cabin, if equipped with a cabin.&lt;/li&gt;&#xA;&lt;li&gt;Fixed landing gear&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that this is not a complete list of FAA requirements, and that regulations for light-sport aircraft (or their equivalent) in other countries may vary.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-03T07:13:52.497" LastActivityDate="2014-01-03T07:13:52.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="552" PostTypeId="4" CreationDate="2014-01-03T04:55:01.367" Score="0" Body="Light Sport aircraft are simple aircraft, generally limited to two seats, a maximum gross weight of 600kg (1320lbs), and a single piston-powered engine driving a propeller, which may be operated by a pilot holding a Sport Pilot certificate or higher." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-03T07:13:45.543" LastActivityDate="2014-01-03T07:13:45.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="553" PostTypeId="2" ParentId="497" CreationDate="2014-01-03T05:08:29.927" Score="6" Body="&lt;p&gt;According to the paper &lt;em&gt;&lt;a href=&quot;http://dspace.mit.edu/handle/1721.1/28892&quot; rel=&quot;noreferrer&quot;&gt;Reconfigurable autopilot design for a high performance aircraft using model predictive control&lt;/a&gt;&lt;/em&gt;, each control surface is updated at a different rate depending on the needs of the overall system.  What they used in their experiments (and is most likely not the same in every aircraft because they will test to see what is required) is as follows:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cqEsu.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The bandwidth column shows you how often the control surface is updated, and ranges from 3.9 times per second (on the slow moving leading edge of the wing) to 13.8 times per second (on the aileron because of the fast response of the airplane to roll control inputs).&lt;/p&gt;&#xA;&lt;p&gt;This is a fixed value selected during the system design, and does not change based on the phase of flight (so it would be the same whether in cruise or in the landing configuration).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-03T05:08:29.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="554" PostTypeId="2" ParentId="550" CreationDate="2014-01-03T05:40:07.420" Score="13" Body="&lt;p&gt;My understanding is that most FAA licenses would also qualify as &quot;ICAO Licenses&quot; (certainly the ATP seems to as we have a bunch of US/FAA certificated ATPs acting as international captains for US airlines flying to/from ICAO member states). From a quick read I think anything from Private up meets the ICAO Annex 1 (personnel licensing) requirements. (It appears that ICAO charges for Annex 1, but &lt;a href=&quot;http://www.cad.gov.rs/docs/atm/ICAO%20Annex%201.pdf&quot;&gt;the fine folks in the Republic of Serbia have made the 2011 edition available on their Civil Aviation Directorate's website&lt;/a&gt; for us to all read and enjoy).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In addition to the Annex 1 requirements, &lt;a href=&quot;http://www.icao.int/safety/AirNavigation/Pages/peltrgFAQ.aspx&quot;&gt;ICAO's FAQ&lt;/a&gt; has the following to say about licensing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;ICAO licence or international licence&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ICAO does not issue any licences. Licences issued by ICAO Contracting States on the basis of Standards and Recommended Practices of Annex 1 – Personnel Licensing, are habitually called ICAO licences. This has led many to believe that there is a specific ICAO or international licence. The fact is that there is not one single international licence issued by ICAO or any other organization. States issue their own licences based on national regulations in conformity with Annex 1 specifications and validate licences issued by other Contracting States on the basis of bilateral or multilateral agreements or the fulfilment of nationally legislated requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;International recognition of flight crew licences&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Convention on International Civil Aviation, often called the Chicago Convention, provides for worldwide recognition of flight crew licences issued by any member State of the International Civil Aviation Organization (ICAO) provided that:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;the licence meets or exceeds the ICAO licensing Standards of Annex 1 – Personnel Licensing to the Convention on International Civil Aviation; and&lt;/li&gt;&#xA;  &lt;li&gt;the licence is used on an aircraft which is registered in the State which has issued or validated the licence.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;If the licence is to be used on an aircraft which is not registered in the issuing State, the licence holder must obtain a validation of the licence from the State of Registry or alternatively obtain a new licence issued by the State of Registry. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically your US/FAA license is a valid &quot;ICAO License&quot; as long as you're flying a US-registered aircraft &amp;amp; the nation you're flying to/through accepts US/FAA licenses (possibly with some additional requirements on a per-country basis).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you got a job for a Serbian airline and needed to fly an aircraft registered in Serbia you would need the Serbian Civil Aviation Directorate to issue you a license (or validate your FAA license) because they are the state of registry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I've read you can get a private license issued pretty easily in most ICAO member states - the procedures are roughly analogous to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.2.1.10&quot;&gt;US FAR 61.75&lt;/a&gt; - but if you want anything more than that there are other hoops to jump through to &quot;convert&quot; your license, which can range from just a written exam to a full-fledged checkride or more -- this is probably what people are referring to when they say it's difficult to get an &quot;ICAO License&quot; issued.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-03T05:40:07.420" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="555" PostTypeId="1" AcceptedAnswerId="559" CreationDate="2014-01-03T07:45:48.317" Score="27" ViewCount="16047" Body="&lt;p&gt;I was watching a documentary about a Lufthansa A380, and they said that the pilot and co-pilot are required to eat different meals; why is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a country-specific requirement, or airline-specific?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="69" LastEditDate="2014-01-18T18:02:23.457" LastActivityDate="2021-05-24T04:05:00.497" Title="Is it true that the pilot and co-pilot are required to eat different meals?" Tags="&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="556" PostTypeId="1" AcceptedAnswerId="570" CreationDate="2014-01-03T07:52:29.073" Score="17" ViewCount="7108" Body="&lt;p&gt;A question on Travel (&lt;a href=&quot;https://travel.stackexchange.com/questions/7814/are-parachutes-allowed-on-airplanes-as-cabin-baggage&quot;&gt;Are parachutes allowed on airplanes as cabin baggage?&lt;/a&gt;) got me to wondering: hypothetically, what items could the &quot;über-paranoid&quot; passenger or pilot bring on-board to potentially save their life in an emergency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I.e. a parachute, oxygen, a portable smoke hood?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the technicalities? I.e. would a parachute be of any use above a certain altitude? What about with oxygen?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2018-12-26T22:35:36.937" Title="What items could you bring on-board to maximise your chance of survival in an emergency?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;emergency&gt;" AnswerCount="8" CommentCount="19" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="557" PostTypeId="2" ParentId="556" CreationDate="2014-01-03T09:42:48.893" Score="23" Body="&lt;p&gt;The two most important things you can bring on board that are likely to save your life in an emergency are &lt;strong&gt;a physically fit body&lt;/strong&gt; and &lt;strong&gt;a ticket to a seat in an exit row&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-01-03T09:42:48.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="558" PostTypeId="2" ParentId="555" CreationDate="2014-01-03T11:30:30.840" Score="10" Body="&lt;p&gt;Although I have no reliable sources to this, I believe that pilots have to eat different meals to avoid food poisoning and therefore becoming sick mid-flight.&lt;/p&gt;&#xA;&lt;p&gt;As for drinks, it should not matter as long as they drink from a separate bottle / can.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; According to the article &lt;a href=&quot;http://www.nytimes.com/1984/03/27/science/the-doctor-s-world-are-pilots-protected-from-contaminated-food.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Are Pilots Protected From Contaminated Food?&lt;/a&gt;, it is not in FAA's policy for the pilots to eat different meals.&#xA;However, the airlines can still choose to make some kind of rule.&lt;/p&gt;&#xA;" OwnerUserId="313" LastEditorUserId="13666" LastEditDate="2021-05-24T00:27:13.000" LastActivityDate="2021-05-24T00:27:13.000" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="559" PostTypeId="2" ParentId="555" CreationDate="2014-01-03T11:51:44.713" Score="33" Body="&lt;p&gt;It is a company specific rule found in the Flight Operations Manual so is airline specific.  There is usually a statement that goes along with it which also says to avoid foods with a higher than typical rate of food poisoning, such as raw fish before and during the Flight.  In the US, the FOM is submitted to, and accepted by the FAA so the procedures become required.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-01-03T20:51:52.103" LastActivityDate="2014-01-03T20:51:52.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="560" PostTypeId="2" ParentId="556" CreationDate="2014-01-03T15:13:11.450" Score="10" Body="&lt;p&gt;I've seen it suggested many times that those seated near the rear of aircraft seem to have higher survival rates in crashes than those seated near the front.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h3iJl.gif&quot; alt=&quot;Diagram of aircraft survival rates in different aircraft areas&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Survival rates for various parts of the passenger cabin, based on an analysis of all commercial jet crashes in the United States since 1971 where detailed seating charts were available. (Illustration by Gil Ahn. Diagram Courtesy of seatguru.com.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.popularmechanics.com/technology/aviation/safety/4219452&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Safest Seat on a Plane: PM Investigates How to Survive a Crash&lt;/em&gt; on  Popular Mechanics&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="8282" LastEditDate="2018-12-26T22:35:36.937" LastActivityDate="2018-12-26T22:35:36.937" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="561" PostTypeId="1" AcceptedAnswerId="574" CreationDate="2014-01-03T16:56:06.383" Score="13" ViewCount="3424" Body="&lt;p&gt;Without relying on winds aloft or LLWS data, can pilots identify wind shear conditions visually, by watching clouds or otherwise?&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-09T01:47:53.520" Title="Can wind shear conditions be identified visually?" Tags="&lt;weather&gt;&lt;wind&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="562" PostTypeId="2" ParentId="561" CreationDate="2014-01-03T17:21:55.230" Score="3" Body="&lt;p&gt;Clouds with flat tops or bottoms (anvil shapes) can indicate wind shear. Fronts are usually accompanied by wind direction and speed changes which can easily be seen in the clouds as the front approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smoke stacks can provide an indication of wind shear if smoke changes direction or shape as it rises. &lt;/p&gt;&#xA;" OwnerUserId="81" LastActivityDate="2014-01-03T17:21:55.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="563" PostTypeId="2" ParentId="561" CreationDate="2014-01-03T18:46:00.430" Score="2" Body="&lt;p&gt;A combination or one or more of the following conditions may indicate wind shear is present:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Indicated airspeed variations in excess of 15 knots&lt;/li&gt;&#xA;&lt;li&gt;Groundspeed variations (decreasing head wind or increasing tail wind, or a shift from head wind to tail wind)&lt;/li&gt;&#xA;&lt;li&gt;Vertical-speed excursions of 500 fpm or more&lt;/li&gt;&#xA;&lt;li&gt;Pitch attitude excursions of five degrees or more&lt;/li&gt;&#xA;&lt;li&gt;Glideslope deviation of one dot or more&lt;/li&gt;&#xA;&lt;li&gt;Heading variations of 10 degrees or more&lt;/li&gt;&#xA;&lt;li&gt;Unusual autothrottle activity or throttle lever position&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are &lt;em&gt;visual&lt;/em&gt; indications in the sense that you're looking at the way the aircraft is performing versus out the window for cues from the environment.&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="287" LastEditDate="2014-01-03T18:54:04.920" LastActivityDate="2014-01-03T18:54:04.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="564" PostTypeId="2" ParentId="481" CreationDate="2014-01-03T20:08:42.537" Score="1" Body="&lt;p&gt;Here's something that leads me to answer in the affirmative, though unlikely:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the TFR (such as the VIP restrictions we often see in the USA) prohibits flight training, but you are on an IFR flight plan and the controller clears you through the TFR, did you still break it? (Such would be the case if you were an instrument student.) I'd say that yes, you did, as you failed to comply with the restrictions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, would you get busted for this? Probably not, unless something else went wrong and the nature of the operation was revealed. (Of course, to avoid this discrepancy, you could say that the CFI was the PIC, and was getting you out of the TFR so that you could conduct training elsewhere.)&lt;/p&gt;&#xA;" OwnerUserId="50" LastActivityDate="2014-01-03T20:08:42.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="565" PostTypeId="1" AcceptedAnswerId="567" CreationDate="2014-01-03T20:15:58.833" Score="14" ViewCount="5244" Body="&lt;p&gt;So one thing that always struck me as kind of odd was when you depart a class D tower (VFR) and you get your departure instructions, that's kind of ... it. You just go on your merry way and switch off frequency whenever you want to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do people just stay on the tower frequency listening until they're outside of the airspace? Or do you give the tower a courtesy call (N123 leaving the class D) when you get to the boundary, and then switch off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, is it legal to switch immediately to another frequency as soon as the tower says 'left turnout approved, resume own navigation'? It always seemed a bit of a hole to me. But, are controllers bothered by a extra &quot;check out&quot; on leaving the class D?&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="572" LastEditDate="2015-04-16T10:28:13.590" LastActivityDate="2015-04-16T10:28:13.590" Title="What is the proper procedure for leaving class D airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;class-d-airspace&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="566" PostTypeId="2" ParentId="565" CreationDate="2014-01-03T20:25:08.290" Score="13" Body="&lt;p&gt;You are responsible for staying on frequency as long as you are in the class D space, UNLESS you are granted an early frequency change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you leave Class D, you are free to change frequencies without notice.&lt;br&gt;&#xA;If its a busy area, many controllers will still give you traffic advisories as long as you're nearby, and its reasonable to stay on frequency until you're considerably outside their space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If its a very quiet area, it might be friendly to tell the controller to have a nice day as you're leaving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason you may want an early frequency change is if you want to talk to another authority ASAP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Boeing Field (KBFI) and Renton Municiple (KRNT) are very close together, with adjoining Class-D spaces.  Its common for practice flights to go between them.&#xA;(&lt;a href=&quot;http://skyvector.com/?ll=47.51986635128485,-122.26706941010242&amp;amp;chart=128&amp;amp;zoom=1&amp;amp;plan=A.K1.KBFI%3aG.47.492123714694095,-122.27341282415671%3aG.47.520820093830565,-122.22085694627012%3aA.K1.KRNT&quot;&gt;Example map&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The conversation may go like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You:&lt;/strong&gt; &quot;&lt;em&gt;Boeing Tower; N513WF: Holding short, Rwy 13L, ready to go; Request early Frequency Change to Renton&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; &quot;&lt;em&gt;3WF: Cleared for Takeoff, Rwy 13L.  Frequency Change approved above 400 feet.  No turns until instructed.&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You get to 400+ feet, then call up Renton:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You:&lt;/strong&gt; &quot;&lt;em&gt;Renton Tower: N513WF, out of Boeing's 13L, request touch-n-gos&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Renton:&lt;/strong&gt; &quot;&lt;em&gt;3WF: Enter Right-traffic, following a Warrior, you're #2&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Congrats:  You're talking to Renton, while still inside Boeing's Delta-space.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-01-03T20:35:33.257" LastActivityDate="2014-01-03T20:35:33.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="567" PostTypeId="2" ParentId="565" CreationDate="2014-01-03T20:37:13.203" Score="16" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html&quot;&gt;AIM covers this from an operations / legal standpoint&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3-2-5. Class D Airspace&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;4. Departures from:&lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(a) A primary or satellite airport with an operating control tower. &lt;strong&gt;Two‐way radio communications must be established and maintained with the control tower, and thereafter as instructed by ATC while operating in the Class D airspace.&lt;/strong&gt; &lt;em&gt;[emphasis mine]&lt;/em&gt;&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While operating in Class D airspace, you must maintain two-way radio contact with the tower – monitor the frequency and be prepared to respond. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may leave the frequency once you are either clear of the airspace, or receive instructions to that end from ATC (&lt;em&gt;&quot;N1234, frequency change approved&quot;&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether or not controllers are &lt;em&gt;bothered&lt;/em&gt; by you letting them know that you've left, I can't say, but it would probably qualify as frequency congestion. If they want to get in touch with you, they'll try (&lt;em&gt;&quot;N1234, are you still with me?&quot;&lt;/em&gt;), but once you're outside the Class D airspace they're generally only providing advisory information.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-04T00:16:11.890" LastActivityDate="2014-01-04T00:16:11.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="568" PostTypeId="1" AcceptedAnswerId="569" CreationDate="2014-01-03T20:48:36.993" Score="27" ViewCount="12059" Body="&lt;p&gt;Leaving aside the claimed &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2011/May/1/Dogfight-Running-lean-of-peak&quot;&gt;pros and cons&lt;/a&gt; of lean-of-peak (LOP) vs. rich-of-peak (ROP), the C172S Lycoming IO-360-L2A handbook I have says &quot;Continuous operation at mixture settings lean of peak EGT is prohibited&quot;, and indeed I was always taught to run the engine ROP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you should always follow the POH for your aircraft, but considering piston engines in general, why would running LOP be prohibited? &lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2020-09-05T15:30:39.960" Title="Why should some piston engines not be run lean of peak?" Tags="&lt;piston-engine&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="569" PostTypeId="2" ParentId="568" CreationDate="2014-01-03T21:20:27.983" Score="26" Body="&lt;p&gt;Considering piston engines in general there's a few reasons not to run &quot;lean of peak&quot;, but the arguments I'm aware of all fall into three broad categories:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Poor Instrumentation&lt;/strong&gt;&lt;br&gt;&#xA;Most folks advocating Lean-of-Peak engine operation will also tell you that you need a good engine monitor (with Exhaust Gas Temperature (EGT) and Cylinder Head Temperature (CHT) probes for &lt;em&gt;each cylinder&lt;/em&gt;) so you can ensure that all your cylinders are operating within safe temperature limits.&lt;br&gt;&#xA;Manufacturer CHT/EGT systems are often &quot;single-probe&quot;. On the IO-360 in your Cessna example that leaves you with a 3 cylinder blind spot in your monitoring, and the potential risk of damaging your engine based on the incomplete information you have.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Uneven mixture distribution&lt;/strong&gt;&lt;br&gt;&#xA;Some engines simply &lt;em&gt;can't&lt;/em&gt; run lean of peak because of uneven mixture distribution: Either the engine will get rough as some cylinders &quot;miss&quot;, or you'll have some cylinders lean of peak EGT and at a safe cylinder head temperature while others are redlining their CHT and potentially causing damage to your engine.&lt;br&gt;&#xA;This sort of uneven mixture distribution happens frequently in carbureted engines, but there are many injected engines which also have poor fuel distribution &amp;amp; significant variation in mixture between cylinders (This is where GAMIJectors makes their money - by providing balanced injectors to even out fuel distribution).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&quot;In Case Something Breaks&quot;&lt;/strong&gt;&lt;br&gt;&#xA;Hypothetical scenario: you are cruising at 8000 feet, you've leaned for cruise, and your mixture control suddenly fails in such a way that your engine is stuck at the current mixture setting.  All the airports within your endurance range are roughly at sea level.&lt;br&gt;&#xA;An engine running lean of peak may begin to run rough as you descend for landing (the mixture becomes too lean to support combustion).  An engine running rich of peak may continue to run acceptably through the descent. (The mixture may transition into &lt;a href=&quot;http://www.oshkosh365.org/saarchive/eaa_articles/2012_12_08.pdf&quot;&gt;&quot;the red box zone&quot;&lt;/a&gt; where operation at high power settings are dangerous, but you'll theoretically be reducing power for your descent, so the chance of doing damage to your engine isn't that high unless you have to perform a go-around or other high-power maneuver.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A prohibition on Lean-of-Peak operation in your POH is probably historically based on #1 or #2 above -- the manufacturer doesn't want to advise you to do something that might damage your engine.  Running Rich-of-Peak is conservative operating guidance, where the downside is slightly increased fuel consumption and the possibility of fouling a spark plug (which is not likely at normal operating power settings) versus the downside of potential engine damage from improper Lean-of-Peak operation.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-03T21:20:27.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="570" PostTypeId="2" ParentId="556" CreationDate="2014-01-03T22:11:34.547" Score="30" Body="&lt;p&gt;Most of the items you can bring with you to maximize your chances of surviving an in-flight emergency are items you're &lt;em&gt;not going to be allowed to bring with you&lt;/em&gt;.&lt;br&gt;&#xA;About the only things I could recommend bringing along on a commercial flight are your cellphone and a personal locator beacon (PLB) of some kind, but frankly if your airliner goes down ATC is going to know where you were when they lost contact, (and the plane has an &lt;a href=&quot;http://en.wikipedia.org/wiki/Emergency_Locator_Transmitter&quot; rel=&quot;noreferrer&quot;&gt;Emergency Locator Transmitter&lt;/a&gt; already).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should also wear &lt;em&gt;sensible clothing&lt;/em&gt; -- natural fibers like wool or cotton are the order of the day if in-flight fire is a concern. Polyester or other synthetic fabrics will melt to your skin and cause you to have a Bad Time.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;More directly addressing your question though, the items that spring immediately to my mind (and why you probably won't be taking them with you) are:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;A parachute (what prompted your question)&lt;/strong&gt;&lt;br&gt;&#xA;Sure, you can bring your parachute. It's kind of a useless security blanket though.&lt;br&gt;&#xA;From cruise flight you'd basically be executing a high-altitude jump &lt;a href=&quot;http://www.halojumper.com&quot; rel=&quot;noreferrer&quot;&gt;(let's say a HALO jump, because you want to get down as quick as you can)&lt;/a&gt;. You would require oxygen to remain conscious longer than about 30-45 seconds (though an automatic-opening chute may save you here), as well as protective clothing to survive the low temperatures while you're free-falling.&lt;br&gt;&#xA;Those concerns aside, remember that airliner cabins are pressurized and the doors are typically &quot;plug doors&quot; that open &lt;em&gt;inward&lt;/em&gt;. No human is strong enough to open that door with the cabin pressurized, and if you've lost cabin pressure for some reason you're better off putting on that little drop-down oxygen mask like the nice flight attendant told you to in the safety briefing. You're not going to save yourself if you pass out from hypoxia while putting on your chute and trying to get to the door.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;An oxygen mask / smoke hood can be useful in a fire.&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most airlines are not going to let you carry an oxygen cylinder onto the plane (as others pointed out in comments, oxygen and in-flight fires can cause more problems than it solves).  That holds true for pretty much any kind of compressed gas because really, how do they know what's in that tank?  &lt;/li&gt;&#xA;&lt;li&gt;A smoke hood using a filter (or a sealed rebreather hood) with no compressed air supply may make it past security, but ask yourself honestly: &quot;Am I proficient enough to use an emergency escape smoke hood in an in-flight emergency?&quot; -- If you can't answer &quot;yes&quot; you're probably putting yourself (and others) in more danger wasting time donning the hood versus just getting out of the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;A life vest (if traveling over water)&lt;/strong&gt;&lt;br&gt;&#xA;This is overkill on an airliner (though those of us that fly little planes should &lt;em&gt;seriously&lt;/em&gt; consider flotation devices when flying over water).&lt;br&gt;&#xA;Your airline seat cushion &lt;em&gt;really&lt;/em&gt; &lt;strong&gt;&lt;em&gt;CAN&lt;/em&gt;&lt;/strong&gt; be used as a flotation device. Those big yellow slides also detach from the plane and make marvelous floats. Frankly if you need any of these items you're in a situation where having your own Mae West isn't going to really enhance your chances of survival.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;A utility knife capable of cutting your seatbelt&lt;/strong&gt;&lt;br&gt;&#xA;This is &lt;em&gt;incredibly&lt;/em&gt; useful for a bunch of reasons, not just cutting your way out of your seatbelt. In fact I keep one in my plane. Sharp and/or pointy things make airport security nervous though - if you try to take such an item on an airline flight it will likely be taken away from you before you get anywhere near the plane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Food and Water&lt;/strong&gt;&lt;br&gt;&#xA;Useful if you have to make an emergency landing in a remote area, but frankly airliners already have beverages (some may even still have food).&lt;br&gt;&#xA;If you're carrying a light snack you're as set as you're going to be in this department.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Emergency Blankets&lt;/strong&gt;&lt;br&gt;&#xA;Nice to have, but most commercial aircraft already have shock blankets on board (and much like food/water, this is really only useful if you have an otherwise uneventful landing in a remote area).&lt;br&gt;&#xA;If it makes you feel better to have your own blanket you can get pre-packed ones that can fit in basically any carry-on for about $5-10.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Signal flares&lt;/strong&gt;&lt;br&gt;&#xA;Again, mainly useful if you have an emergency landing in a remote area (and your PLB and the plane's ELT don't work for some reason). Flares are good both for signaling rescuers and for starting fires to keep warm.&lt;br&gt;&#xA;I don't know if rescue flares are still routinely carried on commercial airliners, but I &lt;em&gt;can&lt;/em&gt; say with reasonable certainty that you will not be allowed to carry on your own. They don't let you smoke on most airlines these days - they're certainly not going to let you carry on a self-igniting flare!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1696" LastEditDate="2016-07-21T21:39:04.667" LastActivityDate="2016-07-21T21:39:04.667" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="571" PostTypeId="2" ParentId="351" CreationDate="2014-01-03T23:42:08.663" Score="19" Body="&lt;p&gt;In &lt;a href=&quot;http://en.wikipedia.org/wiki/Canadian_airspace&quot; rel=&quot;noreferrer&quot;&gt;Canadian Airspace&lt;/a&gt;, Northern Domestic Airspace (NDA) is the area of compass unreliability within which runways and NAVAIDs are oriented to true or grid north versus magnetic north.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should not need to worry about which NAVAID is to true north; simply keep track of whether you're in Southern or Northern Domestic Airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.flytime.ca/files/2013/03/airspace-tc.gif&quot; alt=&quot;NDA and SDA&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.477" LastActivityDate="2015-02-23T15:31:44.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="572" PostTypeId="1" AcceptedAnswerId="573" CreationDate="2014-01-04T03:21:29.500" Score="28" ViewCount="7424" Body="&lt;p&gt;In many places, it's been stated that you should reduce power slowly to prevent engine damage.  Depending on who you talk to, some say you should reduce the manifold pressure by 1 inch per minute, others say two. However, I'm not sure just how reducing power quickly will damage an engine, and if you do, what would happen. Could someone explain?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2015-08-26T12:33:35.787" Title="How can reducing power too quickly on a piston engine damage it?" Tags="&lt;piston-engine&gt;" AnswerCount="7" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="573" PostTypeId="2" ParentId="572" CreationDate="2014-01-04T03:49:37.050" Score="21" Body="&lt;p&gt;The main concern cited in regards to reducing power too quickly is that you could shock cool the engine.  A sudden decrease in power, particularly at high altitudes where it is cold can cause a rapid decrease in temperature of the engine which can cause damage to the cylinder heads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the theory is very controversial because there is no evidence that the cooling causes a problem, and in fact the engine cools much more quickly when you shut it down at the end of a flight.  A very good article going into more specifics about cooling of aircraft engines is here:  &lt;a href=&quot;http://www.avweb.com/news/maint/182883-1.html?redirected=1&quot;&gt;the physics and metallurgy of &quot;shock cooling&quot;&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the more interesting points that it discusses is that only about 12% of the heat generated from combustion ends up making its way through the block and is dissipated by air cooling (cooling fins).  This means that most of the heat is already going somewhere else anyway (the largest part goes out the exhaust), and the &quot;air cooling&quot; doesn't make that big of a difference anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As always, be sure that you follow all recommendations and limitations from your POH or engine manufacturer in regards to engine cooling, CHT's, etc. since they could have procedures for other reasons as well. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-04T17:43:59.300" LastActivityDate="2014-01-04T17:43:59.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="574" PostTypeId="2" ParentId="561" CreationDate="2014-01-04T04:56:38.317" Score="7" Body="&lt;p&gt;Can you see wind shear?  Nope, but you can sometimes see &lt;em&gt;indications&lt;/em&gt; of it.  &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Airbus&lt;/a&gt;, windshear is usually associated with the following weather situations (photos found on Google images by me and are clickable to take you to the source):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jet streams&lt;br&gt;&#xA;&lt;a href=&quot;http://www.redorbit.com/education/reference_library/earth/atmosphere/2582934/wind_shear/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oyNz2m.jpg&quot; alt=&quot;Jet stream photo&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Mountain waves&lt;br&gt;&#xA;&lt;a href=&quot;http://www.siskiyous.edu/shasta/env/clouds/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uRIVRm.jpg&quot; alt=&quot;Mountain wave photo&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Frontal surfaces&lt;br&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Weather_front&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SkDA7m.jpg&quot; alt=&quot;Weather Front - Shelf Cloud&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.windows2universe.org/earth/Atmosphere/front.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bma64m.jpg&quot; alt=&quot;Weather Front&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Thunderstorms and convective clouds (and I added virga here too)&lt;br&gt;&#xA;&lt;a href=&quot;http://www.physicalgeography.net/fundamentals/7t.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vxwxhm.jpg&quot; alt=&quot;Thunderstorm&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://ceres.larc.nasa.gov/ceres_brochure.php?page=3&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eh78em.png&quot; alt=&quot;Convective Clouds&quot;&gt;&lt;/a&gt; &#xA;&lt;a href=&quot;http://www.nc-climate.ncsu.edu/edu/k12/PrecipTypes/body&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MvOQRm.jpg&quot; alt=&quot;Virga&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Microbursts.&lt;br&gt;&#xA;&lt;a href=&quot;http://retreatwx.blogspot.com/2013/04/wind-just-blows-me-away.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c2gBIm.jpg&quot; alt=&quot;Microburst&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://tjsgarden.com/2012/07/09/what-is-microburst-storm/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qOjK8m.jpg&quot; alt=&quot;Microburst&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Avoid these at all cost!  Actually, that's the easy part.  The windshear without the visible signs is more the issue, and &lt;a href=&quot;https://aviation.stackexchange.com/a/563/69&quot;&gt;csatlos's answer&lt;/a&gt; does a good job of telling you what to look for during flight (especially takeoff and landing when you are low and slow).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-01-09T00:32:44.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="576" PostTypeId="2" ParentId="568" CreationDate="2014-01-04T17:20:15.450" Score="-2" Body="&lt;p&gt;Running too far lean of peak is bad for the engine. That's easy to do if the mixture isn't precise enough, or if you descend and forget to adjust the mixture. If there's not much leeway in a particular engine or if the engine is susceptible to damage from running a little too far lean of peak, the manufacturer will prohibit the practice.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-01-04T17:20:15.450" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="577" PostTypeId="1" AcceptedAnswerId="603" CreationDate="2014-01-04T18:09:17.140" Score="29" ViewCount="5832" Body="&lt;p&gt;So the other day as I was flying, I started to wonder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=0GC-yL7tYYU&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ju30g.jpg&quot; alt=&quot;cloud flying&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All pilots should be familiar with basic VFR cloud clearance requirements in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.5.33&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.155&lt;/a&gt; (and if not, then go study now!).  When flying piston airplanes, we probably spend most of our time in the Class E below 10,000 ft. arena:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avstop.com/balloon/heater.htm&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yVsum.jpg&quot; alt=&quot;Class E &amp;lt; 10,000&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is great and all, but how can we actually determine how far away we are (especially vertically)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought about using a sextant and some &quot;simple math&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5g3qf.gif&quot; alt=&quot;sextant&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://tex.stackexchange.com/questions/64100/breaking-an-array-of-equations&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9XJ8s.png&quot; alt=&quot;sample math&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, I need to know my actual distance TO the cloud as well as my angle...  A quick Google search found one of these, but I'm not so sure how it will work with a cloud:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aliexpress.com/item/Vector-Optics-8x30-Laser-RangeFinder-Monocular-SCAN-1200M-w-Rain-REFL-150-Mode-Range-Finder-Distance/634988085.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/go9cw.jpg&quot; alt=&quot;Range Finder&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all seriousness though, how can we stay legal and safe when operating VFR in the vicinity of clouds?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:36:12.570" LastActivityDate="2018-04-10T07:49:11.557" Title="How can I tell how far I am from a cloud?" Tags="&lt;weather&gt;&lt;far-91&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="578" PostTypeId="5" CreationDate="2014-01-04T18:16:25.810" Score="0" Body="&lt;p&gt;Part 61 of the US Federal Air Regulations deals with FAA pilot and instructor certification. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains regulatory requirements pertaining to airman certification in the USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14&quot; rel=&quot;nofollow&quot;&gt;The full text of FAR 61 can be found online, as 14 CFR 61&lt;/a&gt;, as well as in printed form at most pilot shops.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-04T23:38:25.790" LastActivityDate="2014-01-04T23:38:25.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="579" PostTypeId="4" CreationDate="2014-01-04T18:16:25.810" Score="0" Body="Part 61 of the US Federal Air Regulations deals with FAA pilot and instructor certification." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-04T23:38:29.277" LastActivityDate="2014-01-04T23:38:29.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="580" PostTypeId="1" AcceptedAnswerId="583" CreationDate="2014-01-04T18:44:29.297" Score="13" ViewCount="1671" Body="&lt;p&gt;Let's say I want to get night current again, but I haven't flown at night recently so I hire an instructor to fly with me. If I don't count PIC time I don't see a problem, I would just log it as dual instruction. But if I log PIC time, is the instructor considered a passenger? If so I wouldn't be able to have the instructor with me since I am not night current. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an exception for flying with an instructor?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="69" LastEditDate="2014-01-13T04:13:18.517" LastActivityDate="2014-01-13T04:13:18.517" Title="Can I count PIC time when regaining night currency with an instructor?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="581" PostTypeId="2" ParentId="577" CreationDate="2014-01-04T18:53:29.823" Score="17" Body="&lt;p&gt;While distances are hard for many people to estimate, time is much easier for many people to estimate.  Pull out your trusty E6B, and work out the distance in terms of seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, at a cruising speed of 110Kts &lt;em&gt;(typical for many small GA student planes)&lt;/em&gt;,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;3 Miles is 1 minute 30 seconds&lt;/li&gt;&#xA;&lt;li&gt;2000 feet is 10 seconds.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So if you cannot see where you'll be in 1:30, visibility is too low.&lt;br&gt;&#xA;If you can fly to a cloud in less than 10 seconds, you're too close.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flyingmag.com/&quot; rel=&quot;noreferrer&quot;&gt;Flying Magazine&lt;/a&gt; essentially said the same thing in &lt;a href=&quot;http://www.flyingmag.com/technique/tip-week/judging-vfr-cloud-distances&quot; rel=&quot;noreferrer&quot;&gt;&quot;Judging VFR Cloud Distances&quot;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-12-29T20:21:46.813" LastActivityDate="2015-12-29T20:21:46.813" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="582" PostTypeId="2" ParentId="580" CreationDate="2014-01-04T18:57:15.373" Score="4" Body="&lt;p&gt;Here's the FAA's legal definition of a &lt;strong&gt;pilot in command&lt;/strong&gt; from &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/7B29C0FFCE0C430A86256EDF00478339?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt;. Note that this is a definition completely independent from the requirements to &lt;em&gt;log&lt;/em&gt; PIC time:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilot in command means the person who:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) Has final authority and responsibility for the operation and safety of the flight;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) Has been designated as pilot in command before or during the flight; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(3) Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On a flight like this, you may &lt;em&gt;act&lt;/em&gt; as PIC of the flight as long as you are rated for the aircraft, and you may therefore &lt;em&gt;log&lt;/em&gt; PIC time. The CFI can &lt;em&gt;log&lt;/em&gt; PIC time, as an instructor can log all time spent instructing (this would count - you're working on your night landings). &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.51&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51(e)&lt;/a&gt; covers the logging of PIC time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, for some reason, the pilot receiving instruction does not feel competent to &lt;em&gt;act&lt;/em&gt; as the PIC, they can designate the CFI as the PIC based on item (2) of the definition in 14 CFR 1.1. If this is the case, as they're still sole manipulator of the controls, PIC &lt;em&gt;time&lt;/em&gt; may still be &lt;em&gt;logged&lt;/em&gt; by the non-instructing pilot.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-04T20:08:21.563" LastActivityDate="2014-01-04T20:08:21.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="583" PostTypeId="2" ParentId="580" CreationDate="2014-01-04T19:06:59.507" Score="11" Body="&lt;p&gt;You can log PIC time because you are &quot;the sole manipulator of the controls of an aircraft for which the pilot is rated&quot; (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=55da5e17099eb6fa458d6700a7ccaf92&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2.1.1.31&amp;amp;idno=14&quot;&gt;14 CFR 61.51&lt;/a&gt;).  That's all that is required in this case for the pilot to log PIC time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So since a pilot must be night current in order to fly with passengers, (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.1.1.36&quot;&gt;61.57(b)&lt;/a&gt;) the question becomes, &quot;is a flight instructor considered a passenger if they are providing instruction&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA has a &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2008/April/200804_Departments_Legal_Briefing.html&quot;&gt;flight briefing&lt;/a&gt; about this specific scenario where they quote FAA legal interpretations as saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;We agree that, for purposes of section 61.57(b), an authorized&#xA;  instructor providing instruction in an aircraft is not considered a&#xA;  passenger with respect to the person receiving instruction, even where&#xA;  the person receiving the instruction is acting as [pilot in command].&#xA;  (The instructor must be current, qualified to instruct, and hold a&#xA;  category, class, and type rating in the aircraft, if a class and type&#xA;  rating is required.) The instructor is not a passenger because he is&#xA;  present specifically to train the person receiving instruction.&#xA;  Neither is the person receiving instruction a passenger with respect&#xA;  to the instructor. This training may take place, even though neither&#xA;  pilot has met the 61.57(b) requirements.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that they say in this case, since neither of them is a passenger, that technically &lt;strong&gt;&lt;em&gt;neither&lt;/em&gt;&lt;/strong&gt; the pilot or the flight instructor has to be night current.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-05T04:06:47.257" LastActivityDate="2014-01-05T04:06:47.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="584" PostTypeId="1" AcceptedAnswerId="585" CreationDate="2014-01-04T19:47:30.703" Score="11" ViewCount="848" Body="&lt;p&gt;Who runs the Air Traffic Control system in Canada? Is it the government?&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2014-05-16T21:54:39.480" Title="Who runs the Air Navigation System (air traffic control) in Canada?" Tags="&lt;air-traffic-control&gt;&lt;canada&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="585" PostTypeId="2" ParentId="584" CreationDate="2014-01-04T19:47:30.703" Score="12" Body="&lt;p&gt;No. Unlike the United States where the Federal Aviation Administration (FAA) is both the operator and regulator of the air navigation system (ANS), these roles are separated in Canada and performed by two different parties. They are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The regulator: &lt;a href=&quot;http://www.tc.gc.ca/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;code&gt;Tranport Canada - Government of Canada&lt;/code&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;The operator: &lt;a href=&quot;http://www.navcanada.ca/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;code&gt;NAV CANADA&lt;/code&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The Government of Canada passed the &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/acts/C-29.7/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Civil Air Navigation Services Commercialization Act of 1996&lt;/a&gt;, which effectively sold the ANS to a newly-formed corporation, &quot;NAV CANADA&quot; for the price of $1.5 billion dollars. Since 1996, Transport Canada's role has changed to regulation and enforcement; they introduce, amend, revoke, and enforce the Canadian Aviation Regulations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NAV CANADA become the sole operator of the civil ANS and is a private company whose revenues come from aviation customers and technology sales, not Government of Canada.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NAV CANADA operates the civil ANS using 7 Area Control Centres, 41 Control Towers, 56 Flight Service Stations, and 8 Flight Information Centres; military aerodromes and terminal control areas remained the responsibility of the Department of National Defence.&#xA;&lt;img src=&quot;https://i.imgur.com/r5WWL2pl.png&quot; alt=&quot;Map of Canadian FIRs, Towers, FSS, and FICs&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2014-01-04T19:47:30.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="586" PostTypeId="1" AcceptedAnswerId="589" CreationDate="2014-01-04T20:16:19.813" Score="9" ViewCount="35708" Body="&lt;p&gt;FAR 135.385 requires that at your destination airport your flight planning shows that you could make a full-stop landing &quot;within 60 percent of the effective length&quot; of the runway when flying transport-category turbine-powered aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For piston-powered aircraft FAR 135.377 has a similar 70% rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do you calculate minimum runway lengths under these rules?&lt;br&gt;&#xA;Can you use 80% of the runway? What if the runway is wet? &lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="64" LastEditDate="2014-01-04T23:49:46.510" LastActivityDate="2015-04-02T17:03:16.427" Title="How do you calculate minimum runway lengths for Part 135 operations using the 60% rule?" Tags="&lt;runways&gt;&lt;aircraft-performance&gt;&lt;far-135&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="587" PostTypeId="1" AcceptedAnswerId="590" CreationDate="2014-01-04T21:35:01.600" Score="10" ViewCount="7183" Body="&lt;p&gt;As far as I know, most (or all) airplane owners purchase insurance that covers liability, if nothing else. Good idea or not, &lt;strong&gt;is aircraft insurance legally required in the US, in the way that automobile insurance &lt;a href=&quot;http://en.wikipedia.org/wiki/Vehicle_insurance_in_the_United_States&quot;&gt;is required&lt;/a&gt;&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-04T22:41:11.553" Title="Do aircraft owners need to purchase insurance?" Tags="&lt;aircraft-ownership&gt;&lt;liability&gt;&lt;insurance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="588" PostTypeId="1" AcceptedAnswerId="592" CreationDate="2014-01-04T21:38:01.680" Score="13" ViewCount="4966" Body="&lt;p&gt;Per &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/23e90761e5001c628625754500734f2a!OpenDocument&quot;&gt;FAR 91.307&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless each occupant of the aircraft is wearing an approved&#xA;  parachute, no pilot of a civil aircraft carrying any person (other&#xA;  than a crewmember) may execute any intentional maneuver that&#xA;  exceeds...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if I'm flying aerobatics solo, I'm not required to have a parachute. But if I have a passenger, both are required to have one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the rationale for that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that in something like a Super Decathlon, where the pilot must exit the plane before the passenger, it would be senseless to have one for the passenger but not the pilot. But is there anything more to this?&lt;/p&gt;&#xA;" OwnerUserId="26" LastActivityDate="2017-04-02T16:36:21.933" Title="Why a parachute for aerobatics only when carrying a passenger?" Tags="&lt;faa-regulations&gt;&lt;far-91&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="589" PostTypeId="2" ParentId="586" CreationDate="2014-01-04T22:33:28.937" Score="6" Body="&lt;h1&gt;Required runway length for landing&lt;/h1&gt;&#xA;&lt;p&gt;The minimum runway length required for landing under Part 135 operations is, believe it or not, the same as Part 91: You need to be able to land and stop within the available runway length specified in the AFM.   This is what you use when you are getting ready to land.&lt;/p&gt;&#xA;&lt;p&gt;That being said, since you reference the &amp;quot;60%/80% rules&amp;quot;, there is a more stringent requirement that is required as part of your &lt;em&gt;preflight planning&lt;/em&gt; and specified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f6264ba184562097b414fe34a507ebbe&amp;amp;node=14:3.0.1.1.11.9.3.14&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 135.385&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h1&gt;60% Rule for Large Turbine Transport Category Airplanes&lt;/h1&gt;&#xA;&lt;p&gt;This rule is specified in 14 CFR 135.385(b), and says (in part):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;no person operating a turbine engine powered large transport category airplane may take off that airplane unless its weight on arrival ... would allow a full stop landing at the intended destination airport within 60 percent of the effective length of each runway&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So to follow the regulation by the letter, you need to take 60% of the runway length and compare it to your actual landing distance.&lt;/p&gt;&#xA;&lt;h2&gt;Example&lt;/h2&gt;&#xA;&lt;p&gt;We want to land on a 6,000 ft. runway, so our max allowable landing distance is 3,600 ft.:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$6,000ft\times60\%=3,600ft$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Determining minimum runway length&lt;/h2&gt;&#xA;&lt;p&gt;Sometimes pilots prefer to ask the question in a different way, and ask &amp;quot;what is the minimum runway distance needed for the current conditions&amp;quot; instead of &amp;quot;what can my maximum landing distance be.  To calculate this, we simply re-arrange our formula above like this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$Minimum~Runway=\frac{Actual~Landing~Distance}{60\%}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;If our actual landing distance is 3,000 ft. then we would need a minimum field length of 5,000 ft.:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{3,000ft}{60\%}=5,000ft$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;h1&gt;80% Rule&lt;/h1&gt;&#xA;&lt;p&gt;The 80% rule specified in 14 CFR 135.385(f) works exactly the same way, but can only be used by an &amp;quot;An eligible on-demand operator&amp;quot; if approved in accordance with their Operations Specifications (A057 and C049) and the procedures listed in their Flight Operations Manual.&lt;/p&gt;&#xA;&lt;p&gt;You would then replace the 60% with 80% in the above calculations.&lt;/p&gt;&#xA;&lt;h1&gt;Wet Runways&lt;/h1&gt;&#xA;&lt;p&gt;14 CFR 135.385(d) says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(d) Unless, based on a showing of actual operating landing techniques on wet runways, a shorter landing distance (but never less than that required by paragraph (b) of this section) has been approved for a specific type and model airplane and included in the Airplane Flight Manual, no person may take off a turbojet airplane when the appropriate weather reports or forecasts, or any combination of them, indicate that the runways at the destination airport may be wet or slippery at the estimated time of arrival unless the effective runway length at the destination airport is at least 115 percent of the runway length required under paragraph (b) of this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So basically, you use the information from your AFM for wet runway landing distance, or if it isn't provided (since it isn't required), you do the same calculation that you did before but include an additional 15%.&lt;/p&gt;&#xA;&lt;h2&gt;Example:&lt;/h2&gt;&#xA;&lt;p&gt;Taking the example from the 60% rule and assuming that it is wet, we have a max landing distance of 3,130 ft.:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{6,000ft\times60\%}{115\%}=3,130ft$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Minimum Runway Length When Wet&lt;/h2&gt;&#xA;&lt;p&gt;The minimum runway distance with a 3,000 ft. actual landing distance would be 5,750 ft.:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{3,000 ft\times115\%}{60\%}=5,750ft$$&lt;/span&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-17T23:25:58.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="590" PostTypeId="2" ParentId="587" CreationDate="2014-01-04T22:41:11.553" Score="7" Body="&lt;p&gt;Aircraft insurance for personal aircraft is not &lt;strong&gt;&lt;em&gt;legally required&lt;/em&gt;&lt;/strong&gt; by any part of the US FARs, nor to my knowledge is it required by any state government, though I'm only familiar with New York in that regard. (As you'll note from the Wikipedia page you linked to, not all states require automobile insurance either, though most do now...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft insurance is most directly comparable to marine insurance.&lt;br&gt;&#xA;It's generally required by:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Your lender (if you didn't pay cash)&lt;br&gt;&#xA;They want to be sure you have hull coverage so if the plane is damaged they still get paid.&lt;/li&gt;&#xA;&lt;li&gt;Your FBO or Airport Management.&lt;br&gt;&#xA;As a condition of having a tiedown/hangar most FBOs require some form of liability insurance in case you taxi into a building or another plane.&lt;/li&gt;&#xA;&lt;li&gt;Good old-fashioned common sense.&lt;br&gt;&#xA;A light piston single is unlikely to take out a building, but if you have an incident costs can rack up fast. Having someone else to step up and pay those big bills is beneficial.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-04T22:41:11.553" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="591" PostTypeId="2" ParentId="427" CreationDate="2014-01-04T23:05:27.837" Score="11" Body="&lt;p&gt;Changes to federal aviation regulations are listed on the FAA’s Regulatory &amp;amp; Guidance Library (RGL) at &lt;a href=&quot;http://rgl.faa.gov/&quot; rel=&quot;noreferrer&quot;&gt;http://rgl.faa.gov/&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From the home page, click on the database titled &quot;Code of Federal Regulations&quot;&lt;/li&gt;&#xA;&lt;li&gt;On the left, in the navigation tree, select one of the branches under &quot;Historical CFR&quot; (for example, &quot;By Part&quot;)&lt;/li&gt;&#xA;&lt;li&gt;On the right, expand the items leading to the regulation that you are looking for (in this case Part 61)&lt;/li&gt;&#xA;&lt;li&gt;Scroll down to the regulation that you are looking for (61.51) and it will list the original version and all of the revisions:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ai7ZL.png&quot; alt=&quot;61.51 revision history&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each revision is a link which takes you to the regulation as of that version, with links to the NPRM's and dockets so that you can see what has been changed!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-04T23:05:27.837" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="592" PostTypeId="2" ParentId="588" CreationDate="2014-01-04T23:29:13.640" Score="14" Body="&lt;p&gt;Well, as with many issues involving the FAA, the &quot;why&quot; is a bit of a mystery.  Perhaps they thought that the pilot can &quot;lead by example&quot; if a bail-out is needed.  I'd imagine that a lot of passengers would be a little reluctant to jump out of an airplane, but once they see the pilot go I can see them becoming highly motivated!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as not needing the parachute if only crew members are on board, the FAA has long held the view that they aren't protecting pilots from doing stupid things to themselves since they are knowledgeable and informed, but their regulations are to protect the &quot;general public&quot;, or the passengers in this case, who don't know any better.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-05T01:38:03.883" LastActivityDate="2014-01-05T01:38:03.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="593" PostTypeId="1" AcceptedAnswerId="602" CreationDate="2014-01-04T23:45:31.727" Score="17" ViewCount="4503" Body="&lt;p&gt;When the Cirrus was first introduced, it included a Ballistic Recovery System, which shoots a parachute out the rear of the plane that can save a plane and its occupants when something goes wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeing as how this technology has been honed over the past decades, why don't all new planes incorporate this feature?  I would think that any drawbacks outweigh the benefit of not losing one's life when something happens unexpectedly.&lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="97" LastEditDate="2014-11-09T02:34:04.813" LastActivityDate="2014-11-09T02:34:04.813" Title="Why don't all new GA planes include a parachute system?" Tags="&lt;safety&gt;&lt;aircraft-certification&gt;&lt;airframe-parachute&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="595" PostTypeId="1" AcceptedAnswerId="600" CreationDate="2014-01-05T00:07:33.210" Score="14" ViewCount="1516" Body="&lt;p&gt;METARs, TAFs, the area forecast (FA), and flight service briefings are great tools, but if I'm planning a flight with an overnight stay (or a flight that itself might take me a couple of days of travel time) I often feel that the weather picture I'm getting is a little too short-term for my liking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from watching The Weather Channel are there any supplementary weather sources I can look at which are useful for aviation/flight-planning purposes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested mainly in resources for the USA but answers for other countries would be interesting too.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-18T14:53:56.633" Title="How/Where can I get additional weather information for flight planning?" Tags="&lt;weather&gt;&lt;flight-planning&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="596" PostTypeId="2" ParentId="39" CreationDate="2014-01-05T00:18:43.803" Score="6" Body="&lt;p&gt;As @Pondlife states, this will depend on each member state's implementation of the EASA rules but I would expect that the implementations would be similar -- otherwise what is the point of EASA?  (That would be a good question except it would no doubt be closed as being too &quot;opinion based&quot;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've added a link to the relevant UK documentation and marked this as a Community Wiki answer so that hopefully others can expand on this for other states and perhaps add personal experiences.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;UK&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.caa.co.uk/docs/33/CAA_CAP%20804.pdf&quot; rel=&quot;noreferrer&quot;&gt;CAP 804&lt;/a&gt; Section 4, Part Q deals with &quot;Validation and Conversion of Non-EASA licences issued by States other than the UK&quot;.&lt;/p&gt;&#xA;" OwnerUserId="109" LastActivityDate="2014-01-05T00:18:43.803" CommentCount="2" CommunityOwnedDate="2014-01-05T00:18:43.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="597" PostTypeId="2" ParentId="595" CreationDate="2014-01-05T01:26:26.990" Score="3" Body="&lt;p&gt;The (experimental) &lt;a href=&quot;http://rapidrefresh.noaa.gov/HRRRavi/Welcome.cgi?dsKey=hrrr_jet&amp;amp;domain=t1&quot; rel=&quot;nofollow&quot;&gt;High Resolution Rapid Refresh model&lt;/a&gt; is pretty awesome. It's got a huge selection of plots and some aviation-specific filters. It's not particularly forward looking, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most non-aviation forecasts are going to be pretty low detail, unfortunately. I would tend to stick with NOAA source data rather than third party stuff, as I doubt most websites are actually using custom climate models. The &lt;a href=&quot;http://www.cpc.ncep.noaa.gov/products/predictions/814day/&quot; rel=&quot;nofollow&quot;&gt;NOAA Climate Prediction Center has an 8-14 day outlook composite&lt;/a&gt; that might be somewhat useful. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good NOAA source you didn't mention is &lt;a href=&quot;http://aviationweather.gov&quot; rel=&quot;nofollow&quot;&gt;http://aviationweather.gov&lt;/a&gt;, which has a more classic aviation focus in its available data. It has longer-term forecasts, but they often are graphical, low-resolution, and not of particularly great use for long term planning. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-05T01:48:22.380" LastActivityDate="2014-01-05T01:48:22.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="598" PostTypeId="2" ParentId="595" CreationDate="2014-01-05T01:53:51.797" Score="1" Body="&lt;p&gt;As you mention that you are interested for resource in other country other than USA, here is the TAF, METAR/SPECI for Hong Kong International Airport(VHHH/HKG), ang SIGMET for HKFIR(VHHK). You may access them though &lt;a href=&quot;http://www.hko.gov.hk/aviat/amt_e/wxobsfc_e.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.hko.gov.hk/aviat/amt_e/wxobsfc_e.htm&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="328" LastActivityDate="2014-01-05T01:53:51.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="599" PostTypeId="2" ParentId="595" CreationDate="2014-01-05T02:31:25.427" Score="4" Body="&lt;p&gt;One tool I use which is not aviation-specific is the &lt;a href=&quot;http://forecast.weather.gov/product_sites.php?site=NWS&amp;amp;product=AFD&quot; rel=&quot;nofollow&quot;&gt;NWS/NOAA Area Forecast Discussion&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a text-based collection of notes from the forecasters at regional National Weather Service offices, and I've found them to be full of useful &quot;tribal knowledge&quot; about weather patterns in an area.&lt;br&gt;&#xA;I've found the most useful sections are the synopsis through the long-term (about 1-week) discussions. There is a brief aviation-specific section as well, which is also available on &lt;a href=&quot;http://aviationweather.gov/products/afd/&quot; rel=&quot;nofollow&quot;&gt;aviationweather.gov&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-05T02:31:25.427" CommentCount="1" CommunityOwnedDate="2014-01-05T02:31:25.427" ContentLicense="CC BY-SA 3.0" />
  <row Id="600" PostTypeId="2" ParentId="595" CreationDate="2014-01-05T03:09:50.550" Score="4" Body="&lt;p&gt;The Meteorological Service of Canada (MSC), the United States National Weather Service (NWS) and the National Meteorological Service of Mexico (NMSM) have a joint project called &lt;a href=&quot;http://weather.gc.ca/ensemble/naefs/index_e.html&quot; rel=&quot;nofollow&quot;&gt;&lt;code&gt;North American Ensemble Forecast System (NAEFS)&lt;/code&gt;&lt;/a&gt;. I've referred to it in the past to get some outlook on temperature and precipitation amounts more than a couple days in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the NAEFS site:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NAEFS combines state of the art ensemble forecasts, developed at the MSC and the NWS. When combined, the grand ensemble can provide weather forecast guidance for the 1-14 day period that is of higher quality than the currently available operational guidance based on either set of ensembles alone. It allows the generation of a set of forecast products that are seamless across the national boundaries between Canada, the United States and Mexico.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="287" LastActivityDate="2014-01-05T03:09:50.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="601" PostTypeId="2" ParentId="572" CreationDate="2014-01-05T08:20:20.900" Score="14" Body="&lt;p&gt;I'm generally not a fan of the shock-cooling theory myself, but I am a fan of &quot;don't abuse your engine&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Piston engines have &lt;em&gt;lots&lt;/em&gt; of moving parts. Abrupt power changes, whether caused by advancing the throttle or retarding it, cause all of those moving parts to change speeds faster than inertia and kindness would like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to be kind to your engine open or close the throttle at a reasonable pace during normal operations.  Reasonable varies of course - Generally 2-3 seconds from idle to full throttle seems reasonable for takeoffs (you might be a little more aggressive on power-off stall recovery, but taking 1-2 seconds to push the throttle back in shouldn't really affect your recovery).&lt;br&gt;&#xA;On the other side, you should rarely have to go from full-throttle to idle, but when practicing engine-out scenarios or similar taking a second or two to smoothly reduce the power from cruise to idle rather than simply yanking on the throttle is nicer for you and your engine.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of course all of the advice above about being nice to your engine goes out the window in a real emergency - your priority is your safety, the safety of your passengers, and the safety of people on the ground.&lt;br&gt;&#xA;If you actually stall the wing, or need to abort a takeoff, or anything else happens where your first instinct is a rapid power change don't hesitate to &lt;em&gt;rapidly&lt;/em&gt; put the throttle where you need it, and the engine can like it or lump it as long as it does what its told.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-05T09:39:50.970" LastActivityDate="2014-01-05T09:39:50.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="602" PostTypeId="2" ParentId="593" CreationDate="2014-01-05T08:47:49.710" Score="12" Body="&lt;p&gt;Airframe parachutes are becoming an increasingly popular option on newly-certificated aircraft, thanks in part to the track record of successful deployments on Cirrus aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I had to speculate on why they're not showing up in older certificated designs (like the Piper PA-28 or the Cessna 172 &amp;amp; 182) I'd go with the reason I mentioned in my comment: &quot;New&quot; Pipers and Cessnas are basically extended manufacturing runs of &lt;em&gt;very&lt;/em&gt; old designs - going on 50+ years. Changing an existing aircraft design to include the required hardpoints, breakaway panels, etc. for a parachute system would be a &lt;em&gt;substantial&lt;/em&gt; change to the type certificate, and under Part 23 certification rules doing so would cost the manufacturer an equally-substantial sum of money for the design, engineering, and testing required.&lt;br&gt;&#xA;Light GA aircraft sales at the moment are, shall we say, &lt;em&gt;lackluster&lt;/em&gt; -- the additional costs for the engineering, the type certificate update, and the parachute itself would certainly not help matters, as that cost would need to be passed along to the eventual purchaser of parachute-equipped aircraft (which would probably mean putting a 50+ year old classic Piper or Cessna design in the same price category as a clean-sheet Cirrus SR20/SR22).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the mainly-financial reasons above &lt;a href=&quot;https://aviation.stackexchange.com/questions/593/why-dont-all-new-ga-planes-include-a-parachute-system#comment890_593&quot;&gt;Quantas 94 Heavy&lt;/a&gt; has a point regarding weight.  &lt;a href=&quot;http://brsparachutes.com/cessna_182_faq.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;BRS (the premier airframe parachute company) makes a STC'd kit for some Cessna aircraft&lt;/a&gt;.&lt;br&gt;&#xA;This kit costs about 80 pounds of useful load, and on many light GA aircraft the useful load is marginal enough that this added weight means you're effectively sacrificing a passenger to the installation. The Cessna retrofit kit also takes up a substantial amount of space in the baggage compartment &lt;a href=&quot;http://brsparachutes.com/files/brsparachutes/files/BRS%20Cessna%20182%20White%20paper.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;as you can see from their installation white paper&lt;/a&gt;, which is certainly a negative factor as well. Were the chute to be incorporated into the design by Cessna it would likely be installed in a similar location (there just aren't many other places to put it) with a similar cost in weight and cargo space.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-01-05T08:47:49.710" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="603" PostTypeId="2" ParentId="577" CreationDate="2014-01-05T09:24:09.673" Score="18" Body="&lt;p&gt;The answer, as best I can discern it from my training &amp;amp; my own experience, is &quot;&lt;em&gt;You can't!&lt;/em&gt;&quot; -- every instructor I've flown with has said that cloud clearances are the most inadvertently-busted regulation, even when pilots are doing their best to obey the requirements.&lt;br&gt;&#xA;Our eyes and brain are really good at judging distance relative to landmarks and objects of known size (that's how we can tell we're on a &quot;3 mile final&quot; or &quot;8 miles out&quot;), but without known references our ability to estimate distance quickly falls apart, and there simply aren't that many useful landmarks in the sky.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Judging lateral distance to clouds is, at least in my experience, generally easier than vertical distance - as long as you're a fair distance away from the cloud anyway.&lt;br&gt;&#xA;You can roughly estimate the ground position of a cloud pretty easily (and if you can't you can always use its shadow and be &lt;em&gt;pretty close&lt;/em&gt;). You can also usually find features on the ground of known size (runways, for example: You can get the length of the longest runway at a field from your handy VFR sectional), and figure out how many of those are between you and the cloud's ground position.&lt;br&gt;&#xA;Also if you're doing this whole pilotage-and-navigation thing right you know where you are on the chart, and you can visually estimate the ground position of a cloud pretty easily (again if all else fails use its shadow and you'll be close). Break out your plotter and you can figure out how many miles away you are from the cloud (but inside about 3 miles this is going to get pretty difficult, and with your head in the cockpit mucking about with the chart and plotter you may wind up &lt;em&gt;inside&lt;/em&gt; the cloud by the time you're done working up your estimate!).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A final close-in technique for clouds at your altitude is to use your wing. You know your aircraft's wingspan, and you can also say that roughly half that value is the length of one wing. Figure out how many &quot;wings away&quot; the cloud is, and do the math -- of course if you're at a distance where you can do that kind of visual estimation you're likely to be close to the cloud clearance limits.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Judging vertical distance is harder.  The usual advice if you're below the clouds is to get the cloud heights from a local airports ATIS or AWOS and use that as a guide.  If you're above the clouds PIREPs for cloud tops serve the same purpose.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Visually if you're &lt;em&gt;above&lt;/em&gt; the cloud the same skills you use to judge your height above a runway will work. The catch is those skills really only work when you're within about 1000 to 2000 feet (i.e. &quot;By the time you can really judge the distance you may already be too close!&quot;).&lt;br&gt;&#xA;Coming up from below a cloud you're basically relying on judging your closing speed to an object of unknown / nebulous size: As you approach the cloud it's going to get bigger, but you don't really know how big it's going to get before you wind up inside it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a final visual cue in any direction, remember that clouds aren't clearly-defined boundaries - Often you'll see little wispy streaks of cloud around you as you're getting closer to the cloud you're trying to avoid (particularly when approaching from below). This is a pretty definitive indication that you're probably closer to the cloud than you should be, and you should start heading &lt;em&gt;away&lt;/em&gt; from the cloud before you wind up inside it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I think the best bottom-line practical advice I've ever gotten on cloud clearances, loosely paraphrased from a couple of the local CFIs: &quot;Just stay way the heck away from clouds until you're instrument rated and on an IFR flight plan.&quot; and &quot;If you think you might be too close to a cloud, get further away!&quot; -- the latter probably being what the FAA is getting at with their statutory distance requirements.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-05T09:24:09.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="604" PostTypeId="2" ParentId="348" CreationDate="2014-01-05T11:14:18.017" Score="10" Body="&lt;p&gt;I finally found several arguments to answer this question from different sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sweep and Mach Number from Airbus&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This argument is developed in an &lt;a href=&quot;https://www.airbus.com/content/dam/corporate-topics/publications/fast/FAST05.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus magazine from 1985&lt;/a&gt;. To grasp it it is important to understand the purpose of swept wing. By sweeping the main wings one introduces an angle between the leading edge of the wing and a line perpendicular to the fuselage axis. Let's consider two airplanes, one with swept wings (A) and one with straight wings (B).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most important parameters is the Mach Number experienced by the wings. It is measured normal to the leading edge of the wing which means that for the two airplanes flying at the same Mach Number, the Mach Number seen by wings of (B) is larger than the one seen by the wings of (A). This allows to fly at higher speed because it delays the large increase in drag (drag divergence) and other effects linked to the Mach Number around the airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if the isobars on the wing are not aligned with the leading edge, they are following a less swept pattern which tends to reduce the benefits from the sweep angle of the main wing because the effective sweep angle is smaller and the Mach Number around the wing should not be computed normal to the leading edge but normal to the isobars close to the leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a theoretical point of view it would even be better to have isobars not aligned with the leading edge but having a larger sweep angle. However this never happens due to boundary conditions at the root and the tip of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Other sources&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this is also explained &lt;a href=&quot;https://web.archive.org/web/20161026014351/http://adg.stanford.edu/aa241/drag/sweepncdc.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, this last &lt;a href=&quot;http://www.flightglobal.com/pdfarchive/view/1964/1964%20-%200023.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt; deals also with the matters but does not justify the need for the isobars to be parallel to the leading edge. It deals more with the shock on the wing and the ways to weaken it and thus reduce the drag.&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="14897" LastEditDate="2019-03-22T08:19:39.837" LastActivityDate="2019-03-22T08:19:39.837" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="605" PostTypeId="1" AcceptedAnswerId="616" CreationDate="2014-01-05T15:35:29.580" Score="10" ViewCount="10656" Body="&lt;p&gt;Some aircraft have pusher type propellers.  In what ways is it different from a tractor type propeller?  What's are the advantages and disadvantages over a tractor type.&lt;/p&gt;&#xA;" OwnerUserId="177" LastEditorUserId="19" LastEditDate="2017-03-17T08:57:04.503" LastActivityDate="2017-03-17T08:57:04.503" Title="What are the differences in aircraft performance between tractor and pusher propeller designs?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="606" PostTypeId="1" AcceptedAnswerId="609" CreationDate="2014-01-05T15:57:01.947" Score="42" ViewCount="21146" Body="&lt;p&gt;So I was looking at the &lt;a href=&quot;http://www.alexander-schleicher.de/produkte/asw27/asw27_main_e.htm&quot;&gt;description of a ASW 27 B glider&lt;/a&gt; and ran across this statement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Two water tanks in the wing plus a further 35 liter tank in the&#xA;  fuselage enable the ASW 27 B to carry more water ballast than any&#xA;  other 15 m glider and also give it the widest range of wing loadings&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If a glider is trying to stay aloft as long as possible, wouldn't it be better to be light?  Why would you add ballast and be able to dump it?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="34686" LastEditDate="2020-03-13T02:17:25.940" LastActivityDate="2020-03-13T18:04:53.517" Title="Why would a glider have water ballast? If it is trying to stay aloft without an engine, wouldn't it be better to be as light as possible?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;aircraft-physics&gt;&lt;glider&gt;&lt;descent&gt;" AnswerCount="8" CommentCount="3" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="607" PostTypeId="1" AcceptedAnswerId="608" CreationDate="2014-01-05T17:00:36.633" Score="7" ViewCount="979" Body="&lt;p&gt;Part 135 instrument currency in a jet aircraft requiring two pilots, requires both pilots to be instrument current. But how about the same situation for a Part 91 flight? Does the SIC need to have his 6 approaches with tracking, intercepting, holding etc... in the last 6 months?&lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="1696" LastEditDate="2015-04-17T14:32:11.440" LastActivityDate="2015-04-17T14:32:11.440" Title="Is Part 91 Instrument currency for SIC similar to Part 135 requirements?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;far-91&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="608" PostTypeId="2" ParentId="607" CreationDate="2014-01-05T17:32:39.717" Score="3" Body="&lt;p&gt;Only if you fall under the Fractional rules (Subpart K).  Otherwise SIC currency requirements for turbojet airplanes are specified in 14 CFR 91.531, which requires you to be current via 14 CFR 61.55 and has no instrument &lt;em&gt;currency&lt;/em&gt; requirement (although you do need your instrument &lt;em&gt;rating&lt;/em&gt; to fly under IFR).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T15:48:37.693" LastActivityDate="2014-01-18T15:48:37.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="609" PostTypeId="2" ParentId="606" CreationDate="2014-01-05T19:16:04.257" Score="60" Body="&lt;p&gt;&lt;em&gt;Mass doesn't affect the maximum distance, only the maximum endurance.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, image two identical planes A and B: A weights 50kg less than B. Assuming no wind (horizontal / vertical) and speed of best glide, both gliders will land at the exact same spot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lighter airplane A however will arrive later than B, as the speed of best glide is less than for B. In conclusion you can say, that additional mass only increases cruise speed, but not the travel distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glider competitions are most of the time a route you have to fly in the shortest time possible. So that means, if you have a higher speed of best glide, you can fly faster in competitions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only downside to having a higher weight is, that your liftrate in thermals will be decreased and due to the higher speed it is harder to center the thermals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is to some extend also possible to shift the Centre of Gravity (CG) with the added load. The further it is to the aft limit, the higher your maximum distance is. This is because you will have less down-force from the stabilizer required. (If the CG is at the front limit, you will need to pull the control stick in order to fly level, therefore you have more drag). However I think this is rather a positive side effect and most of the time the water is used for flying faster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: I am a glider pilot and currently doing my ATPL training.&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="213" LastEditDate="2014-01-06T02:20:58.313" LastActivityDate="2014-01-06T02:20:58.313" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="610" PostTypeId="2" ParentId="534" CreationDate="2014-01-05T19:35:25.333" Score="4" Body="&lt;p&gt;There are a lot of differences in the US and European communication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I got my AZF about a year ago and basically you have to do simulated IFR departure and approach. In addition you will have to fill out an IFR flightplan and answer 30 IFR communication questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say it is a similar difficulty like the BZF, it might be even a little bit easier, as you just have to repeat what the controller tells you (but you still have to be aware where you are).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example on how radio communication is done can be found at &lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP413Supplement.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.caa.co.uk/docs/33/CAP413Supplement.pdf&lt;/a&gt; or &lt;a href=&quot;http://training.ivao.de/trainingsunterlagen.html?tx_drwiki_pi1%5Bkeyword%5D=IFR-Funkbeispiel&quot; rel=&quot;nofollow&quot;&gt;http://training.ivao.de/trainingsunterlagen.html?tx_drwiki_pi1%5Bkeyword%5D=IFR-Funkbeispiel&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would however recommend a training at a flight school (which costs around 150 Euros).&lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-05T19:35:25.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="611" PostTypeId="2" ParentId="372" CreationDate="2014-01-05T20:51:39.497" Score="1" Body="&lt;p&gt;Absolutely report leaving the previously assigned altitude.  And this applies equally when receiving a clearance &quot;cleared for the approach.&quot;  I recall once being cleared for an approach from a holding pattern.  Planes were stacked above me.  I wanted to maintain my holding altitude until over the holding fix.  Thus I did not say, &quot;Leaving 2000 feet.&quot; I left that altitude quickly when approach control told the plane above me to descend to 2,000 feet.&lt;/p&gt;&#xA;" OwnerUserId="331" LastActivityDate="2014-01-05T20:51:39.497" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="612" PostTypeId="2" ParentId="606" CreationDate="2014-01-05T22:10:21.857" Score="4" Body="&lt;p&gt;Force's answer is pretty much &lt;em&gt;the&lt;/em&gt; answer, but also consider that mass = inertia. If you weigh more, you are less likely to be disturbed by any given outside force (turbulence). A lighter plane is more maneuverable but it will also bounce around a lot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot comment on how much of an effect the ballasts in question have on this for a glider, though.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-05T22:10:21.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="613" PostTypeId="1" AcceptedAnswerId="617" CreationDate="2014-01-05T22:51:49.070" Score="27" ViewCount="23664" Body="&lt;p&gt;I was just curious, in the past, smoking on planes was permitted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the law surrounding smoking in your own private plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iCCJz.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-18T21:41:53.187" LastActivityDate="2017-09-23T20:35:52.273" Title="Is it legal to smoke in your own plane?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="614" PostTypeId="2" ParentId="556" CreationDate="2014-01-05T23:17:46.703" Score="13" Body="&lt;p&gt;I would like to add a thunderer whistle to the list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iD5rlt.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A thunderer whistle is an essential survival tool not only after a plane crash. It enables you to be heard miles away when rescue teams are looking for you. It helps them find you quicker, and if you're capable to, you can also morse. Finally, a thunderer whistle is small and light. I have one in my flight bag.&lt;/p&gt;&#xA;" OwnerUserId="332" LastEditorUserId="97" LastEditDate="2014-03-14T07:17:55.443" LastActivityDate="2014-03-14T07:17:55.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="615" PostTypeId="1" AcceptedAnswerId="619" CreationDate="2014-01-05T23:35:06.140" Score="17" ViewCount="9460" Body="&lt;p&gt;Are there any regulations the FAA has ruled to get into a Control Tower? Do people need any special kind of security clearance? Are there forbidden items or other special rules?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd also want to know if there's a way for non-pilots (your average civilian Joe) to get into a Control Tower.&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="3201" LastEditDate="2016-03-04T07:48:00.733" LastActivityDate="2016-03-04T07:48:00.733" Title="What is the security policy for getting into a Control Tower in the US?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;usa&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="616" PostTypeId="2" ParentId="605" CreationDate="2014-01-06T00:58:10.140" Score="12" Body="&lt;p&gt;Well one major difference is the blade pitch, pusher props will seem to be backwards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You must also modify the engine's bearings to be able to support the propeller mounting and crankshaft in compression, rather than tension.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pusher prop's engine also has to be cooled differently than a tractor, because the propeller is not blowing air over the engine. Therefore some ducting and ram air magic has to be done, or some other system of cooling implemented. Many pusher-type planes have had severe issues with cooling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: some of the next few might not necessarily apply to pusher-type planes where the engine is mounted above the fuselage, like the Lake Amphibian and many other seaplanes, or some other oddities like the B-36. I am talking about more conventional pushers like the Velocity, Beech Starship, or Cessna 337.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue is FOD. A pusher prop will likely be mounted behind at least one of the wheels, which can kick dirt and rocks up into the propeller. Now imagine a prop that is very close to one of the mains. Even on paved runways you encounter rocks and debris occasionally, and it only takes one hit in the right place to produce a failure-causing nick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compounding on that last one, when a tractor-type plane takes off, beacause the prop is forward of the center of mass, the propeller will rotate &lt;em&gt;up&lt;/em&gt;, away from the ground. But a pusher prop is usually just the opposite: it will rotate &lt;em&gt;down&lt;/em&gt; a bit, increasing the chances of a prop-strike. This is one that is heavily considered and worked-around while building pusher-type planes, but while you can mitigate the danger by placing the prop closer to the CM, or making the landing gear taller, you can't completely remove it as far as I know.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-01-06T01:49:28.653" LastActivityDate="2014-01-06T01:49:28.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="617" PostTypeId="2" ParentId="613" CreationDate="2014-01-06T01:15:15.703" Score="23" Body="&lt;p&gt;The short answer to &quot;Can I smoke in my own private aircraft?&quot; is &quot;Yes, usually&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Promised, I looked up the relevant FAR (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.10&amp;amp;idno=14#14:1.0.1.3.10.4.86.72&quot;&gt;23.853 - Passenger &amp;amp; Crew Compartment Interiors&lt;/a&gt;).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual rule is long and verbose, but pretty common sense. The important &lt;em&gt;regulatory&lt;/em&gt; bits for most personal aircraft are just two points though. You must:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Have &quot;an adequate number&quot; of self-contained ash trays&lt;br&gt;&#xA;You don't want flicked ash or a snubbed cigarette to start an in-flight fire.&lt;/li&gt;&#xA;&lt;li&gt;Have &quot;No Smoking&quot; signs you can illuminate, if the passenger/crew compartments are separated&lt;br&gt;&#xA;This doesn't apply to most of us since our &quot;personal&quot; airplanes are light singles, but if you've got a fancy twin with a curtain or door between you and the passengers you'll need those signs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For &quot;commuter category&quot; aircraft there are &lt;em&gt;even more&lt;/em&gt; requirements. Those requirements don't apply to most &quot;personal&quot; planes, so even though it's probably a good idea to meet some of those requirements if you're going to allow smoking in your personal aircraft they're not &lt;em&gt;legally required&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All that said, while it's &lt;em&gt;likely&lt;/em&gt; legal (unless you've removed your ashtrays or your plane didn't come with them) common sense generally dictates you don't want to smoke in your plane - It's bad for the vacuum-driven instruments' filters, will require even more attention to cleaning the inside of your windows, and a loose cigarette in turbulence or a bunch of ashes blown about by an open air vent can be a pretty substantial distraction.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-06T01:15:15.703" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="618" PostTypeId="2" ParentId="615" CreationDate="2014-01-06T01:40:32.177" Score="5" Body="&lt;p&gt;I've arranged tours of two control towers (a class D and a class B) and a TRACON without any issues. I was only required to provide proof of US citizenship, from what I remember.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You must turn OFF (not airplane mode) cell phones before entering the tower or active part of the TRACON.&lt;/p&gt;&#xA;" OwnerUserId="81" LastActivityDate="2014-01-06T01:40:32.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="619" PostTypeId="2" ParentId="615" CreationDate="2014-01-06T01:52:22.153" Score="18" Body="&lt;p&gt;It is still possible (and in my experience not that difficult) to get FAA tower tours (and sometimes even TRACON or Center tours), though you should be reasonable in your expectations here -- You are probably &lt;strong&gt;&lt;em&gt;NOT&lt;/em&gt;&lt;/strong&gt; going to get a tour of the tower at JFK or LAX.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FAA used to actively encourage pilots with an instrument rating (or pursuing instrument training) to sign up for ATC facility tours under a program called &lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/10732&quot;&gt;&quot;Operation Raincheck&quot;&lt;/a&gt; -- This program is still running, though it's been &lt;em&gt;substantially&lt;/em&gt; scaled back (Poke around on the FAA Safety Team's &lt;a href=&quot;https://faasafety.gov/SPANS/events/EventList.aspx&quot;&gt;SPANS system&lt;/a&gt;, or sign up for notices in your area and keep a sharp eye out. &lt;a href=&quot;http://faasafety.gov/SPANS/event_details.aspx?eid=52727&amp;amp;caller=/SPANS/events/EventList.aspx&quot;&gt;Tours usually have a &lt;strong&gt;&lt;em&gt;very&lt;/em&gt;&lt;/strong&gt; limited number of slots available, and they fill up fast!&lt;/a&gt;).&lt;br&gt;&#xA;(As an example of how quickly the slots fill up, when N90 (New York TRACON) last had a Raincheck event it was full within a few hours of being announced. No, I didn't get a slot.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;At towered GA airports - particularly ones with a lot of flight training - you can also contact the tower directly. &lt;a href=&quot;http://flighttraining.aopa.org/flightbag/forms/atc.pdf&quot;&gt;The printed AOPA Airport Directory has facility numbers in it&lt;/a&gt; but that's a little out of date. You can also get the phone number from Flight Service, the local FSDO, or ask the tower/ground controller for the number if they're not too busy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you call the facility explain that you're a pilot/student pilot and would like to arrange to tour the facility (and if possible shadow a controller). They will usually ask for your name, address, airman certificate number, and a few other things to run a check and get approval to let you in to the facility. You will also be expected to have government issued photo ID with you when you show up.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;My experience arranging a tour of our local tower was extremely pleasant - they are happy to do the tours and let you shadow a controller, and I even got to pick their brains about some peculiarities in local procedures.&lt;br&gt;&#xA;It's a great educational experience, and I would recommend it for any pilot/student pilot.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-06T01:52:22.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="620" PostTypeId="1" CreationDate="2014-01-06T02:37:11.883" Score="6" ViewCount="352" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7f43be430ca6f4b806aeacb2ee1b23a8&amp;amp;node=47:5.0.1.1.2.3.95&amp;amp;rgn=div7&quot; rel=&quot;nofollow&quot;&gt;47 CFR 87.87&lt;/a&gt; requires the captain of a US registered aircraft to have their Restricted Radiotelephone Operator Permit (RP) unless it is a domestic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do you go about getting one?  I used the FCC's website a long time ago and remember that it is terribly confusing.  A great answer would include step-by-step directions for those that haven't had to do it yet!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="609" LastEditDate="2015-01-11T03:36:30.807" LastActivityDate="2015-01-11T03:36:30.807" Title="The captain of an aircraft flying an international flight is required to have a Restricted Radiotelephone Operator Permit. How do you get one?" Tags="&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="622" PostTypeId="1" AcceptedAnswerId="639" CreationDate="2014-01-06T05:06:10.183" Score="15" ViewCount="4526" Body="&lt;p&gt;If there seems to be very little traffic at an untowered airport, and no one's replied to any of your radio calls, is it acceptable to just fly a straight-in approach to the runway, or should you still fly the full traffic pattern to final? It just seems like it would be a waste of time and fuel when it's not really necessary. Is there anything wrong with doing so?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="19" LastEditDate="2017-01-16T14:09:42.203" LastActivityDate="2020-02-17T06:54:18.850" Title="Is a full traffic pattern required when there is no traffic at an untowered airport?" Tags="&lt;approach&gt;&lt;traffic-pattern&gt;&lt;non-towered-airport&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="623" PostTypeId="2" ParentId="622" CreationDate="2014-01-06T05:16:16.277" Score="6" Body="&lt;p&gt;It is legal. The left downwind pattern entry at a 45 degree angle is recommended in the AIM to standardize operations and is therefore not regulatory in nature. However, the reason it's not a particularly good idea is that not all aircraft are required to have radios at a non-towered airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A traffic pattern is quite small compared to the en route phase or an instrument approach, there's not much time or fuel to be wasted.&lt;/p&gt;&#xA;" OwnerUserId="338" LastActivityDate="2014-01-06T05:16:16.277" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="624" PostTypeId="2" ParentId="622" CreationDate="2014-01-06T05:25:07.737" Score="12" Body="&lt;p&gt;See &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2090-66A/%24FILE/AC90-66A.pdf&quot;&gt;AC 90-66A - RECOMMENDED ‘STANDARD TRAFFIC  PATTERNS AND PRACTICES FOR AERONAUTICAL OPERATIONS AT AIRPORTS WITHOUT OPERATING CONTROL TOWERS&lt;/a&gt;  for information about uncontrolled airport traffic patterns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It includes the following which says that while the FAA recommends using the full pattern, it is not required:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h1&gt;7. GENERAL OPERATING PRACTICES.&lt;/h1&gt;&#xA;  &#xA;  &lt;p&gt;a. Use of standard traffic patterns for all ‘aircraft  and CTAF procedures by radio-equipped aircraft  are&#xA;  recommended at all airports without operating  control towers.&#xA;  However, it is recognized that other  traffic patterns may already be&#xA;  in common use  at some airports or that special circumstances or &#xA;  conditions exist that may prevent use of the standard  traffic pattern  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And then:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;e. The FAA encourages pilots to use the standard  traffic pattern.&#xA;  However, for those pilots who choose  to execute a straight-in&#xA;  approach, maneuvering for  and execution of the approach should be&#xA;  completed  so as not to disrupt the flow of arriving and  departing&#xA;  traffic. Therefore, pilots operating in the  traffic pattern should be&#xA;  alert at all times to  aircraft executing straight-in approaches.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;f. Pilots who wish to conduct instrument  approaches should be&#xA;  particularly alert for other aircraft in the pattern SO as to avoid&#xA;  interrupting  the flow of traffic. Position reports on the CTAF &#xA;  should include distance and direction from the  airport, as well as&#xA;  the pilot’s intentions upon completion of the approach&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-06T05:25:07.737" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="625" PostTypeId="2" ParentId="620" CreationDate="2014-01-06T05:53:24.807" Score="6" Body="&lt;p&gt;You have to use the remarkably obtuse &lt;a href=&quot;http://wireless.fcc.gov/uls/index.htm?job=home&quot; rel=&quot;nofollow&quot;&gt;FCC Universal Licensing System&lt;/a&gt; if you want to request a license online. You'll specifically need &lt;a href=&quot;http://transition.fcc.gov/Forms/Form605/605.html&quot; rel=&quot;nofollow&quot;&gt;FCC Form 605&lt;/a&gt;, the apparently very-accurately-named &quot;Quick-Form Application for Authorization in the Ship, Aircraft, Amateur, Restricted and Commercial Operator, and General Mobile Radio Services&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From there, you're on your own, I'm afraid. I applied for mine years ago and it looked identical.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Do note that this is essentially a fee on operators who fly internationally, as there's no exam to complete and no proof of eligibility to provide. You simply request the license and pay the application costs. It's a bit silly.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-13T01:34:54.740" LastActivityDate="2014-01-13T01:34:54.740" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="626" PostTypeId="2" ParentId="622" CreationDate="2014-01-06T07:59:48.070" Score="2" Body="&lt;p&gt;There are a few airports out there with this line in their AF/D page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;STANDARD TFC PATTERN REQUIRED OF ALL ACFT.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://skyvector.com/airport/MBT/Murfreesboro-Municipal-Airport&quot; rel=&quot;nofollow&quot;&gt;Such as KMBT, as seen here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure how legally binding this is, but it is written.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-06T07:59:48.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="627" PostTypeId="1" AcceptedAnswerId="633" CreationDate="2014-01-06T10:10:31.027" Score="34" ViewCount="32326" Body="&lt;p&gt;One of my life goals is to learn how to fly a plane. I can't do it now due to time constraints, but I am curious: How much, in general terms, does it cost to learn how to fly? I.e. piloting lessons, license fees, etc. I would be doing it in the US.&lt;/p&gt;&#xA;" OwnerUserId="339" LastActivityDate="2016-07-10T23:16:04.307" Title="How much, generally speaking, does it cost to learn how to fly?" Tags="&lt;usa&gt;&lt;flight-training&gt;&lt;cost&gt;&lt;student-pilot&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="628" PostTypeId="2" ParentId="627" CreationDate="2014-01-06T10:56:57.283" Score="6" Body="&lt;p&gt;Highly depends on where you go. The big pt 141 school north of me charges \$9,000-12,000. You'll learn in IFR equipped mid-80's model 172's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Learn with me or my partner, and you'll pay about \$6,000 if you don't waste time. We have a 172C and a 172M. They're not really IFR equipped (they &lt;em&gt;are&lt;/em&gt; but not enough for any &lt;em&gt;real&lt;/em&gt; IFR flying) but they're well maintained and all that. Without sacrificing safety, we keep our costs to a minimum and that's passed directly on to the student.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big school has a good part 141 curriculum and great instructors, but the average guy wanting to learn to fly doesn't need a special course or high-tech instruments and other costly devices for training. It's far cheaper to learn with the basics and then transition into that other stuff when you need it. I can promise people they're not missing anything, because I went through a 141 college program and I'm teaching the exact same stuff, almost the same way under part 61.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I would say to look at \$6,000-\$10,000, depending on the aircraft and your location.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="97" LastEditDate="2014-04-17T01:01:54.440" LastActivityDate="2014-04-17T01:01:54.440" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="629" PostTypeId="2" ParentId="627" CreationDate="2014-01-06T13:03:34.837" Score="8" Body="&lt;p&gt;StallSpins answer is probably correct, however as you haven't flown a plane before, I suppose you don't know a lot of aircraft terminology (like VFR/IFR) either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, you should know that there are different types of licenses. The one you want to do is the PPL - a Private Pilot License. In the US this enables you to fly single-engine Planes during the day and the night in so called &quot;VFR-Conditions&quot;, meaning that you navigate by matching a map with the terrain below you and fly a course you defined before. Obviously you cannot fly if you cannot see much of the terrain, there are some minimums like visibility in order to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also you cannot use this license for commercial actions like shipping cargo or transporting persons, if you get more money from it than it actually costs you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though most schools advertise that the PPL costs 6000-9000 USD, this only includes the minimum hours (and I have been told by US flight instructors that it is not possible to actually stay within the minimum hours). I would therefore say it costs at least 10,000 to 14,000 USD, depending on how good you perform.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is still cheaper than my European PPL, I paid about twice as much for it. &lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-06T13:03:34.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="630" PostTypeId="2" ParentId="622" CreationDate="2014-01-06T13:47:29.220" Score="6" Body="&lt;p&gt;Nobody on the radio does NOT mean no traffic.  You have IFR Arrivals not yet released by approach to tower frequency, and you have 100% legal no radio aircraft.  Fly the pattern so that they know where to look for you!&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-06T13:47:29.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="631" PostTypeId="2" ParentId="627" CreationDate="2014-01-06T15:44:06.313" Score="23" Body="&lt;p&gt;The minimum required hours of instruction is 40 hours.  How many will you need to get the license?  That depends on a lot of factors.  Very few students are good enough at 40 hours to pass the practical test.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can only fly once per week, you will &quot;forget&quot; some of what you learned on the last lesson.  &quot;Forget&quot; is in quotes because some of the forgetting is intellectual, and some is forgetting the sight picture and muscle memory of what you should be doing.  Bottom line is that if you only fly once per week it will take longer.  It took me about 70 hours over a period of about one year, flying once per week with the usual weekends not flying for family obligations and weather.  70 hours was, back then, about the national average.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So multiply 70 hours by your flight school and CFI's combined hourly rate.  Then add some for ground schooling.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-06T15:44:06.313" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="632" PostTypeId="2" ParentId="428" CreationDate="2014-01-06T15:55:57.313" Score="4" Body="&lt;p&gt;Ground running your engine is not good for it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The objective is to get the oil hot enough to boil off any acidic water created by exhaust gas blow by (exhaust gas leaking around the piston rings and ending up in the crank case).  The oil temp should get up to 180 degrees (measured at the temperature sensor) which means it is much hotter down in the bearings etc. so the water is vaporized.  You can't do this on the ground without getting your cylinders too hot!  The only solution to this dilemma is to fly the plane whenever possible in the winter.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other suggestion: to use CamGuard in the oil is a good one.  It keeps a layer of oil on the crank and camshafts longer than other products.  This lengthens the time you can let the plane sit safely between flights.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-06T15:55:57.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="633" PostTypeId="2" ParentId="627" CreationDate="2014-01-06T16:14:25.767" Score="36" Body="&lt;p&gt;Assuming a regular private pilot's license (i.e. not sport/recreation), a part 61 instructor, and a rented aircraft, then you need to budget for the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft rental (this usually includes oil and fuel)&lt;/li&gt;&#xA;&lt;li&gt;Instructor time (air and ground)&lt;/li&gt;&#xA;&lt;li&gt;Materials (books, DVDs, charts, fuel tester etc.) as recommended by your instructor&lt;/li&gt;&#xA;&lt;li&gt;Headset&lt;/li&gt;&#xA;&lt;li&gt;Third-class medical&lt;/li&gt;&#xA;&lt;li&gt;Insurance&lt;/li&gt;&#xA;&lt;li&gt;Written test fee&lt;/li&gt;&#xA;&lt;li&gt;Examiner's fee for the actual test&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If we assume the aircraft costs \$120/hr wet (i.e. including oil and fuel), an instructor costs \$40/hr and you need 50 hours to be ready for the test (40 is the minimum required) then you can do a calculation like this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;35 flying hours with instructor: \$5600&lt;/li&gt;&#xA;&lt;li&gt;15 flying hours solo: \$1800&lt;/li&gt;&#xA;&lt;li&gt;15 hours ground school (instructor's time): \$600&lt;/li&gt;&#xA;&lt;li&gt;Materials: \$500&lt;/li&gt;&#xA;&lt;li&gt;Headset: \$500&lt;/li&gt;&#xA;&lt;li&gt;Third-class medical: \$150&lt;/li&gt;&#xA;&lt;li&gt;Renter's insurance: \$700 (per year)&lt;/li&gt;&#xA;&lt;li&gt;Written test fee: \$150&lt;/li&gt;&#xA;&lt;li&gt;DPE test fee: \$400 (plus \$120 rental for the aircraft)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Total: \$10,520&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can play around with these numbers, there's a lot of variation and research is obviously important. But the single largest cost will be the number of flying hours you need, so anything you can do to reduce that time is worthwhile and the simplest - but unfortunately not the easiest - way to do it is to fly as much as possible, i.e. several times a week. Given weather and other factors, you should probably even plan to fly more than you actually can on paper: a bunch of flights will certainly be cancelled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also train in the most 'minimal' aircraft you can find: a two-seater aircraft without a glass panel could be \$50/hr cheaper than a four-seater with a G1000. Unless you have a very clear idea about what sort of flying you'll do in the longer term there's no point in paying for anything that isn't directly required for the private pilot's test.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="97" LastEditDate="2014-04-17T01:01:06.873" LastActivityDate="2014-04-17T01:01:06.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="634" PostTypeId="1" AcceptedAnswerId="635" CreationDate="2014-01-06T16:40:48.370" Score="12" ViewCount="1839" Body="&lt;p&gt;I was taught during my private pilot training to only provide the minimum information necessary to the FAA when they ask for something so that you don't open yourself up to more scrutiny.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that spirit, what am I legally required to provide to an FAA inspector during a ramp check?  If they ask for something, can I tell them &quot;No&quot; or &quot;I will respond to that in writing within 30 days after I have my lawyer review your question&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my car, I can refuse to let them look inside unless they have a search warrant.  Does the same apply with a private airplane?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2017-10-23T23:24:16.203" Title="What information am I legally required to provide during a FAA ramp check?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="635" PostTypeId="2" ParentId="634" CreationDate="2014-01-06T17:06:43.200" Score="10" Body="&lt;p&gt;AOPA has a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/FAA-Enforcement/Ramp-Checks&quot; rel=&quot;nofollow noreferrer&quot;&gt;good article&lt;/a&gt; on this topic:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You're required to present pilot and medical certificates (plus logbook if required for flight)&lt;/li&gt;&#xA;&lt;li&gt;The inspector may not detain you&lt;/li&gt;&#xA;&lt;li&gt;The inspector may not board the aircraft without informing you&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But an inspector is authorized to check the following items:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The airworthiness certificate&lt;/li&gt;&#xA;&lt;li&gt;The aircraft registration&lt;/li&gt;&#xA;&lt;li&gt;The operating handbook&lt;/li&gt;&#xA;&lt;li&gt;The weight and balance information&lt;/li&gt;&#xA;&lt;li&gt;The minimum equipment list (if applicable)&lt;/li&gt;&#xA;&lt;li&gt;Aeronautical charts (if applicable)&lt;/li&gt;&#xA;&lt;li&gt;The general airworthiness of the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The ELT battery&lt;/li&gt;&#xA;&lt;li&gt;A VOR check&lt;/li&gt;&#xA;&lt;li&gt;The seats/safety belts.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, saying as little as possible seems to be a good plan:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the ramp check is due to a possible violation, anything you say or&#xA;  do may be used against you.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If you have enrolled in AOPA's Legal Services Plan, call AOPA's Pilot&#xA;  Information Center at 800/USA-AOPA immediately. The consequences for&#xA;  even minor infractions can be far more serious than you might think.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for a search warrant, a ramp check is an FAA administrative process, not a law enforcement action. The issue of law enforcement checking private aircraft is a &lt;a href=&quot;http://www.aopa.org/AOPA-Live.aspx?watch=%7BC77BAA09-5142-44EB-83CF-BA2EE899AFF3%7D&quot; rel=&quot;nofollow noreferrer&quot;&gt;hot topic&lt;/a&gt; currently and AOPA provides a &lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/News/All%20News/2013/June/CBPGuidelinesKneeboard.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;checklist&lt;/a&gt; in case you are stopped for search. Their recommendation is to refuse the search (unless they have a warrant, of course) but not interfere if they go ahead and do it anyway.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="18572" LastEditDate="2017-10-23T23:24:16.203" LastActivityDate="2017-10-23T23:24:16.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="636" PostTypeId="2" ParentId="627" CreationDate="2014-01-06T17:20:28.527" Score="12" Body="&lt;p&gt;I added mine up after I finished, and it came to about \$12,000 over about 18 months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I didn't push myself to finish as cheaply or quickly as possible.&lt;br&gt;&#xA;I think I finished around 55 hours.&lt;Br&gt;&#xA;(I also flew out of a relatively expensive airport/region)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If cost is a major factor, you can find ways to trim some costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, every moment you spend preparing, studying, &quot;chair-flying&quot;, and practicing procedures on the ground is a cost that you don't need to incur in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make sure you have each procedure down solid, know your target airspeeds, altitudes, and courses, then hopefully when you get in the air, you won't have any wasted maneuvers because you forgot to setup properly.  Make every moment of actual HOBBS time count towards flying experience, and not for something that could've been covered on the ground, and you can probably trim 25% or more off the cost.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="97" LastEditDate="2014-04-17T01:02:46.110" LastActivityDate="2014-04-17T01:02:46.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="637" PostTypeId="1" AcceptedAnswerId="649" CreationDate="2014-01-06T17:30:53.687" Score="11" ViewCount="410" Body="&lt;p&gt;Say, anybody who made an outstanding contribution to technology, flight methodologies, etc (for example, the Wright Brothers); has the FAA ever issued a license (private pilot, etc.) to anyone that deserved such honor?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="69" LastEditDate="2014-01-18T17:09:32.580" LastActivityDate="2014-01-18T17:09:32.580" Title="Has the FAA ever granted anybody a license honoris causa?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;faa-approval&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="639" PostTypeId="2" ParentId="622" CreationDate="2014-01-06T18:07:25.430" Score="7" Body="&lt;p&gt;I'd like to answer your question with a short example. A few days ago I flew to Venice (untowered) and decided to make a teardrop entry to set up for the 45. My calls were 10 and 5 miles out, both ending with &quot;any traffic please advise.&quot; Guess what I saw overtaking me on my 4 o'clock position only a few hundred feet away at same altitude (500 feet above pattern)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is legal to make a straight in, but before you think about the time or fuel you waste please think about your own and even the guys who's not on CTAF and obviously heads down safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly the 45 and the continue the pattern (it's not always left, check your sectional and the A/FD) everybody knows what the other one is doing and if necessary can act accordingly. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="995" LastEditDate="2020-02-17T06:54:18.850" LastActivityDate="2020-02-17T06:54:18.850" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="640" PostTypeId="2" ParentId="534" CreationDate="2014-01-06T18:18:13.073" Score="0" Body="&lt;p&gt;Training at a flight school is absolutely recommended. It is true that the AZF is a lot easier then the BZF exam, but you should be aware of what's coming up and that's not done by reading but by practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the controller is in a good mood on your exam day you may have spent a little to much money on preparation, but if they had no breakfast that morning you are happy to be used for copying clearances you will never hear when you are sitting in a plane and no longer at a table.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="64" LastEditDate="2014-01-08T21:59:26.070" LastActivityDate="2014-01-08T21:59:26.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="641" PostTypeId="2" ParentId="595" CreationDate="2014-01-06T18:41:45.053" Score="5" Body="&lt;p&gt;In my eyes, it's always a good idea to call WX BRIEF the evening before your planned flight (if you don't know your registration at this time, the pilot's last name is sufficient) and ask for a outlook briefing. Before you call check the TAFs and SIGWX charts available at &lt;a href=&quot;http://aviationweather.gov/products/swl/&quot; rel=&quot;nofollow&quot;&gt;http://aviationweather.gov/products/swl/&lt;/a&gt; so you have a good idea what the briefer is talking about. These guys are really helpful and especially when you call in the evening hours they take a lot of time to discuss the weather situation with you and even answer related questions or suggest other weather sources which may be helpful for your particular operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For you who don't know WX BRIEF: it's a free number 1800WXBRIEF (18009927433) you can dial in the US to get a standard, abbreviated, or outlook briefing. This service is provided by Lockheed Martin flight services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need help to interpret weather information you will find the answer to your question in &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/215166&quot; rel=&quot;nofollow&quot;&gt;Advisory circular 00-45G&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="2984" LastEditDate="2014-08-18T14:53:56.633" LastActivityDate="2014-08-18T14:53:56.633" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="642" PostTypeId="1" CreationDate="2014-01-06T18:43:54.923" Score="6" ViewCount="287" Body="&lt;p&gt;Also wondering which agencies regulate weather modification activities? Any idea where I can find more information about this?&lt;/p&gt;&#xA;" OwnerUserId="344" LastEditorUserId="69" LastEditDate="2014-01-18T18:07:33.637" LastActivityDate="2016-02-16T11:14:56.243" Title="What United States state and federal agencies generally participate in aerial weather modification?" Tags="&lt;weather&gt;&lt;usa&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="643" PostTypeId="1" AcceptedAnswerId="645" CreationDate="2014-01-06T19:23:41.513" Score="21" ViewCount="5042" Body="&lt;p&gt;In some light aircraft, like a Cessna 172, the pitot tube is heated but the exterior static port isn't. The usual reason I've heard is that static ports are much less susceptible to icing, but why is that the case?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="65" LastEditDate="2015-03-03T15:43:33.627" LastActivityDate="2015-03-03T21:09:44.270" Title="Why the pitot tube is heated but the static port isn't?" Tags="&lt;aircraft-design&gt;&lt;flight-instruments&gt;&lt;pitot-static&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="644" PostTypeId="2" ParentId="643" CreationDate="2014-01-06T19:29:11.333" Score="3" Body="&lt;p&gt;Because &lt;em&gt;static ports are much less susceptible to icing&lt;/em&gt;, exactly as you said.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Also because alternate static sources are available.  If your static port ices up, you can pull the lever for alternate static source, and get another air-source from inside the cabin)&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-06T19:29:11.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="645" PostTypeId="2" ParentId="643" CreationDate="2014-01-06T19:36:24.850" Score="15" Body="&lt;p&gt;You'll find your answer if you take a look at the form of a pitot tube or other kinds of ducts where pitot (or total) pressure is taken and compare it to the parts of the aerofoil where ice is prone to accumulate. Ice will most likely form on the leading edge of thin surfaces in the airstream but not on the side of the fuselage. If ice would built up there you will probably have some more urgent problems then switching to your alternate static source ;)&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="946" LastEditDate="2015-03-03T20:31:03.907" LastActivityDate="2015-03-03T20:31:03.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="646" PostTypeId="2" ParentId="642" CreationDate="2014-01-06T19:53:59.113" Score="0" Body="&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Weather_modification#US_National_Oceanic_and_Atmospheric_Administration&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the US, the National Oceanic and Atmospheric Administration keeps records of weather modification projects on behalf of the Secretary of Commerce, under authority of Public Law 92-205, 15 USC § 330B, enacted in 1971&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Also read up on &lt;a href=&quot;http://en.wikipedia.org/wiki/Chemtrail_conspiracy_theory&quot; rel=&quot;nofollow&quot;&gt;ChemTrails&lt;/a&gt; and the CIA.)&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-06T19:53:59.113" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="647" PostTypeId="2" ParentId="508" CreationDate="2014-01-06T20:13:41.833" Score="8" Body="&lt;ul&gt;&#xA;&lt;li&gt;Who you are:&lt;br&gt;&#xA;&lt;code&gt;Cherokee 1234A, a P28A&lt;/code&gt;&lt;/li&gt;&#xA;&lt;li&gt;Where you are:&lt;br&gt;&#xA;&lt;code&gt;10 miles north of La Belle VOR, altitude 6000 feet&lt;/code&gt;&lt;/li&gt;&#xA;&lt;li&gt;Build your own &quot;METAR&quot;:&lt;br&gt;&#xA;&lt;code&gt;Five minutes ago (time) wind aloft 230 @ 24 (wind) imc (visibility) medium turbulence (weather phenomena) broken clouds at my altitude, clear below (cloud cover) temperature 10 degrees (temperature)&lt;/code&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's it!&lt;br&gt;&#xA;There might be a way to exactly meet the form the controller needs to write it down, but this works fine and you have a fluent and well structured report. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="64" LastEditDate="2014-01-10T16:23:54.040" LastActivityDate="2014-01-10T16:23:54.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="648" PostTypeId="1" AcceptedAnswerId="659" CreationDate="2014-01-06T21:17:19.503" Score="26" ViewCount="11623" Body="&lt;p&gt;Runway numbers in most of the world are based on the runway's orientation relative to magnetic north.  For example a runway with a magnetic heading of 135° to 144° will be numbered &lt;code&gt;14&lt;/code&gt;, and one with a magnetic heading of 145° to 154° will be numbered &lt;code&gt;15&lt;/code&gt;.&lt;br&gt;&#xA;Runway numbers are &lt;a href=&quot;http://www.mercurynews.com/breaking-news/ci_24613702/earths-magnetic-shift-causes-first-change-runway-numbers&quot;&gt;occasionally changed&lt;/a&gt; due to changes in the Earth's magnetic field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At my home field Runway &lt;code&gt;14/32&lt;/code&gt; is oriented 145.7°/325.7°, per the &lt;a href=&quot;https://i.stack.imgur.com/tMhdP.png&quot;&gt;FAA's airport diagram&lt;/a&gt;, and it has been this way for some time (I first recall noticing it over a year ago).&lt;br&gt;&#xA;My understanding is that this runway should, at some point, be renumbered &lt;code&gt;15/33&lt;/code&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the FAA determine when to request that an airport change its runway numbers?&lt;br&gt;&#xA;Is the decision to update the runway designation made by the FAA, or by the airport's management?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2019-04-06T13:22:05.833" Title="How do airports determine when they should change their runway numbers?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;&lt;magnetic-variation&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="649" PostTypeId="2" ParentId="637" CreationDate="2014-01-06T21:19:22.103" Score="11" Body="&lt;p&gt;It's an interesting question, and &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2012/April/18/Meet-the-artist-who-designed-your-certificate&quot;&gt;according to AOPA&lt;/a&gt; they did award one to the guy who designed the current FAA license card:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA awarded Dahlvang his own (honorary) certificate, nicely framed&#xA;  with a gold seal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But it doesn't say what's printed on that certificate and I assume it isn't actually valid for flight. If you give someone a real pilot's license you give them the authority to operate an aircraft and I can't imagine the FAA handing out licenses to unqualified people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orville Wright did get an honorary certificate, as did other 'old-timers', but that pre-dates the FAA and again it isn't clear if they were 'real' certificates or not:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://corescholar.libraries.wright.edu/special_ms1_photographs/1523/&quot;&gt;Orville Wright&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://earlyaviators.com/eparkeva.htm&quot;&gt;Evan J. Parker&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I don't know if that really answers the question, but anyway in practical terms I think it's probably a lot easier for the FAA to come up with a suitably impressive but legally worthless certificate rather than give someone a real one and deal with the legal issues involved in breaking their own rules and possibly federal law.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-06T21:19:22.103" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="650" PostTypeId="2" ParentId="643" CreationDate="2014-01-06T21:39:44.120" Score="16" Body="&lt;p&gt;Some aircraft &lt;strong&gt;DO&lt;/strong&gt; heat the static port, if only by side effect: Piper PA28 aircraft (Cherokee/Warrior/Archer/Arrow ) for example have the static port located on the pitot mast.  When pitot heat is turned on in these aircraft the entire mast heats up, including the static port.&lt;br&gt;&#xA;This characteristic would be the same on most aircraft with a combined pitot/static mast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why most light aircraft don't heat the static port, there are two big reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, as you've heard, static ports are normally not located in areas susceptible to icing -- they're on the side of the fuselage in areas of relatively undisturbed air (on most of the Cessnas I'm familiar with they're forward of the doors, on other aircraft they're right around where the registration numbers get painted). As &lt;a href=&quot;https://aviation.stackexchange.com/a/645/64&quot;&gt;Falk pointed out&lt;/a&gt; this means ice normally won't accumulate there.&lt;br&gt;&#xA;As an additional protection some aircraft have multiple external static ports (connected to a shared static line) so that if one port &lt;em&gt;does&lt;/em&gt; get iced over you still have a source of reference pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, a static failure is relatively easy to deal with - particularly in unpressurized light aircraft.  Many unpressurized aircraft that are regularly flown in instrument conditions will have an alternate static source in the cabin (which is simply a valve that opens the static line to cabin air), or the traditional &quot;break the VSI glass&quot; solution can be used to get a mostly-working altimeter.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-01-07T03:09:46.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="651" PostTypeId="2" ParentId="648" CreationDate="2014-01-06T22:23:00.030" Score="3" Body="&lt;p&gt;There is no real need to change the runway identifier just because the variation changed. Sometimes this is done but you'll find enough places aroud the world where there is up to a 10 degree offset (maybe even more) between the numbers on the runway and it's magnetic orientation. At some biger airports with more then three parallel runways this is even done by purpose because if you already have xx left, center and right you can't call the fourth &quot;right right&quot; but what you do is you name them xx left and right and xx+1 left and right see for exampel LAX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets think about the use of the runway numbers. I only need them to x-check if I'm on the right runway prior to departure, to have a reference while approaching an airfield and to quickliy calculate the x-wind - my math isn't so good that five degrees would make a difference ;) and the other things are for sure important but also work out with some offset (I have never seen intersecting runways with only 10 degrees difference in orientation where a confusion would be possible)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no source where I found this but in my eyes it's very dependent on the importance of the airfield if they change it when there are more then 6 degrees offset or not.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-01-06T22:28:23.663" LastActivityDate="2014-01-06T22:28:23.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="652" PostTypeId="2" ParentId="568" CreationDate="2014-01-06T22:48:29.887" Score="5" Body="&lt;p&gt;The lyc O-320 happens to be prone to exhaust valve guide wear. Heat accelerates wear. Running LOP generally causes the exhaust valve to run hotter than running ROP and wear out much faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an ROP environment, the extra fuel that is not burnt lands on many of the top end components including the exhaust valve. As it evaporates off the surface or out of the fuel/air charge, it cools the component or charge slightly (kinda like water evaporating  off your skin cools it down). &#xA;May not sound like much, but it makes a big difference in the rate of wear of top end components.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="340" LastEditDate="2014-01-06T23:00:47.410" LastActivityDate="2014-01-06T23:00:47.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="653" PostTypeId="1" AcceptedAnswerId="658" CreationDate="2014-01-06T23:15:19.963" Score="9" ViewCount="900" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/626/64&quot;&gt;StallSpin's answer&lt;/a&gt; on the recent question about VFR traffic patterns has got me thinking about the &quot;Remarks&quot; section of the Chart Supplement (formerly the Airport/Facility Directory).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are all taught in training to review the Supplement entry for airports we intend to visit (part of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=02c6f60140d060eeb2763799c09b8e15&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.2.4.2&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.103's&lt;/a&gt; &quot;become familiar with all available information&quot; requirement), and to comply with any restrictions noted - typically things like &quot;no touch-and-go landings&quot;, &quot;Standard traffic pattern required of all aircraft&quot;, &quot;Prior Permission Required for jet aircraft&quot;, etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from it being The Right Thing To Do, and avoiding the possibility of local fines/sanctions, are the remarks in the Supplement &quot;regulatory&quot; such as to &lt;em&gt;require&lt;/em&gt; compliance, or are they &lt;em&gt;advisory&lt;/em&gt; where compliance is encouraged but not mandatory?&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-10-07T17:26:39.497" Title="Are remarks in the Chart Supplement (A/FD) &quot;regulatory&quot; or &quot;advisory&quot;?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;&lt;chart-supplement&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="654" PostTypeId="1" AcceptedAnswerId="661" CreationDate="2014-01-06T23:25:01.970" Score="44" ViewCount="36748" Body="&lt;p&gt;I realised that this question is very broad, but I intend it as an example to illustrate the actual costs incurred by a typical long-haul commercial flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purpose of this question, I would assume the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A380 or (modern) B747 in typical 3-class configuration&lt;/li&gt;&#xA;&lt;li&gt;Full occupancy&lt;/li&gt;&#xA;&lt;li&gt;12 hours flight time (or more)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here are the cost position I can think of right now:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuel&lt;/li&gt;&#xA;&lt;li&gt;Aircraft amortisation&lt;/li&gt;&#xA;&lt;li&gt;In-flight crew salaries&lt;/li&gt;&#xA;&lt;li&gt;Ground crew salaries (boarding crew, aircraft preparation and cleaning, luggage loading, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Catering&lt;/li&gt;&#xA;&lt;li&gt;Various insurances&lt;/li&gt;&#xA;&lt;li&gt;Airport fees (landing tax, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Overflight fees&lt;/li&gt;&#xA;&lt;li&gt;Administrative cost (managing/issuing tickets, etc.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What am I missing? What would be the absolute (and relative) cost budget for each of these? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: in airline operations, is this cost typically handled as &quot;per flight hour&quot; (as in general aviation), &quot;per flight&quot;, or in another way?&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="13197" LastEditDate="2016-02-14T18:30:48.560" LastActivityDate="2017-09-02T18:09:23.977" Title="What's the typical cost (and its breakdown) for a long-haul commercial flight?" Tags="&lt;cost&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="655" PostTypeId="1" AcceptedAnswerId="656" CreationDate="2014-01-06T23:34:33.463" Score="11" ViewCount="26685" Body="&lt;p&gt;EASA requires pilots to log separately night time and night landings in the personal logbook. Now, I'm not sure in which period of time a landing is a night landing and flight time is night flight time. I would appreciate your answer, maybe also with a trustworthy source. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="20401" LastEditDate="2018-04-27T23:22:50.947" LastActivityDate="2018-04-27T23:22:50.947" Title="What is the EASA definition of night time?" Tags="&lt;easa-regulations&gt;&lt;night-flying&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="656" PostTypeId="2" ParentId="655" CreationDate="2014-01-07T00:02:06.283" Score="11" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.easa.europa.eu/agency-measures/docs/opinions/2011/04/Annexes%20to%20Regulation.pdf&quot;&gt;this handy document from EASA&lt;/a&gt;, &lt;code&gt;night&lt;/code&gt; is defined as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;…the period between the end of evening civil twilight and the beginning of morning civil twilight, or such other period between sunset and sunrise as may be prescribed by the appropriate authority, as defined by the Member State.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(The FAA and ICAO use a similar definition.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You can get the Civil Twilight times from &lt;a href=&quot;http://www.sunrisesunset.com/predefined.asp&quot;&gt;a convenient astronomical calendar&lt;/a&gt;, but ignoring the specifics, the same rule of thumb the FAA uses for purposes of night currency will likely work for you too:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Night starts one hour after sunset&lt;br&gt;&#xA;(Sunset being when the last of the visible sun disc drops below the horizon.)&lt;/li&gt;&#xA;&lt;li&gt;Night ends one hour before sunrise&lt;br&gt;&#xA;(Sunrise being when the first of the visible sun disk breaks the horizon.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This actually cheats you out of a few minutes of &quot;night&quot; on either side of the calculation, but it's conservative guidance if you're conservative in what you log you won't accidentally mess up and give yourself more night time than you're really entitled too (i.e. you won't make yourself &quot;night current&quot; when you really aren't).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that I'm a US pilot -- since all my flying and training is based on FAA regs in the US if I'm completely off the mark and any European pilots or CFIs want to set me right it would be much appreciated :-)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-07T00:02:06.283" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="657" PostTypeId="2" ParentId="622" CreationDate="2014-01-07T02:33:26.310" Score="2" Body="&lt;p&gt;It is recommended in the AIM and elsewhere that you use the traffic pattern. However, the FAR requires only that you make any turns in the proper direction, not that you fly the pattern or enter the pattern on downwind. Straight in approaches are not prohibited. (91.126)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Unless otherwise authorized or required, each person operating an aircraft on or in the vicinity of an airport in a Class G airspace area must comply with the requirements of this section.... When approaching to land at an airport without an operating control tower in Class G airspace... Each pilot of an airplane must make all turns of that airplane to the left unless the airport displays approved light signals or visual markings indicating that turns should be made to the right, in which case the pilot must make all turns to the right;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Otherwise authorized or required&quot; applies to circling approaches, in which turns may be made in any direction (opening up a whole new set of risks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safety and common sense may dictate that you fly the pattern as a matter of practice. It is also safer to announce your position, and to announce &quot;left (or right) downwind&quot; and &quot;left (or right) base&quot;, in case you or the plane you don't see happens to be going the wrong direction.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-01-07T02:33:26.310" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="658" PostTypeId="2" ParentId="653" CreationDate="2014-01-07T03:13:22.697" Score="3" Body="&lt;p&gt;A required rule in the airport/facility directory is required. It is a very good idea to check the AFD entry online (or on paper) before you fly to a new airport. It just takes a second and you can learn important things, such as &quot;NO DEPS AFT 2230&quot; or &quot;PPR FOR TKOF ON RY 15. CTC FBO 970-920-2016&quot; (&lt;a href=&quot;http://www.airnav.com/airport/kase&quot; rel=&quot;nofollow&quot;&gt;Aspen&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-01-07T03:13:22.697" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="659" PostTypeId="2" ParentId="648" CreationDate="2014-01-07T05:30:21.277" Score="18" Body="&lt;p&gt;Implementing changes to runway numbers is quite complicated and requires a lot of different parties to get involved.  There is a ton of related information in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.19E.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 8260.19E&lt;/a&gt; and it has the details.&lt;/p&gt;&#xA;&lt;h1&gt;Simple Version&lt;/h1&gt;&#xA;&lt;p&gt;According to an article by the NBAA called &amp;quot;&lt;a href=&quot;http://www.nbaa.org/ops/airports/20110314-magnetic-north.php&quot; rel=&quot;noreferrer&quot;&gt;How Changes in Magnetic North Are Impacting Airports&lt;/a&gt;&amp;quot;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;“Adjustments to runways like this and to navigational aids are&#xA;ongoing,” according the Kathleen Bergen, a spokeswoman for the FAA&#xA;Southern Region. “Every five years, the FAA reevaluates shifts in the&#xA;pole—its magnetic variation—and makes changes to runways and flight&#xA;procedures as needed,” she said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h1&gt;Medium Version&lt;/h1&gt;&#xA;&lt;p&gt;NOAA, NOS, and NGS (see below) provide the magnetic variation information, and publish it every five years.  They work with a bunch of different offices, and different branches of the military as they make adjustments.  When a determination is made that a runway number should be changed, they coordinate with several other groups (such as AeroNav Products, OSG-FPT, the applicable Airportt Traffic Service Area Office, and the Airports Division), to choose the actual number used, based on &amp;quot;careful consideration and evaluation of a number of factors&amp;quot; and then to make the actual changes in charting, runway markings and signs, etc.&lt;/p&gt;&#xA;&lt;p&gt;They are supposed to change it when it is more than three degrees off from what it is &lt;em&gt;should&lt;/em&gt; to be.  &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5340_1l.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5340-1L - Standards for Airport Markings&lt;/a&gt; contains the official runway designator rules (paraphrased):  If the actual magnetic course of the runway ends in 5, it can use either number, otherwise you round to the closest runway number (there are some variations for special cases like parallel runways and such, but this covers most runways). So in your example, 145 is still valid as runway 14, and they wouldn't need to change it until it exceeds 148 deg.  In your case, the annual rate of change for Farmingdale airport (as of 2010) is 0.0 deg East, so I don't see that happening for awhile.&lt;/p&gt;&#xA;&lt;h1&gt;Long Version - Quotes from FAA Order 8260.19E (above)&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Section 5. Implementing Epoch Year Magnetic Variation (MV)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;a. &lt;strong&gt;Background.&lt;/strong&gt; The National Oceanic and Atmospheric Administration&#xA;(NOAA), National Ocean Service (NOS), and the National Geodetic&#xA;Survey (NGS), for all areas of the United States and its territories&#xA;for application to navigation charts and maps, is the source for&#xA;magnetic variation (MV) information and tools for establishing&#xA;magnetic variation. Changing values for MV are tabulated and published on&#xA;a 5-year epoch basis; e.g., 00, 05, 10, 15, 20, etc. In order to&#xA;assist in stabilizing the National Airspace System (NAS), a fixed&#xA;value of MV is assigned to each  navigational aid and airport as the&#xA;Magnetic Variation of Record. This value is applied to true&#xA;directions to obtain the magnetic values for radials, courses,&#xA;bearings, and headings published in instrument flight procedures.&#xA;Periodic updating of the MV assigned to navigation facilities is&#xA;required to maintain reasonable proximity of alignment with the&#xA;earth’s ever-changing magnetic field. ...&lt;/p&gt;&#xA;&lt;p&gt;b.&#xA;&lt;strong&gt;Participating Offices.&lt;/strong&gt; Management and control of Epoch Year MV values&#xA;require action  by the following offices:&lt;br /&gt;&#xA;(1) AeroNav Products.&lt;br /&gt;&#xA;(2) Military Organizations.&lt;br /&gt;&#xA;(3) National Flight Data Center (NFDC).&lt;br /&gt;&#xA;(4) Western, Central, and Eastern Technical Operations.&lt;br /&gt;&#xA;(5) Western, Central, and Eastern OSG-FPTs.&lt;br /&gt;&#xA;(6) Regional Airports Divisions.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;f. &lt;strong&gt;Regional Airports Division/Airports District Office (ADO).&lt;/strong&gt;&#xA;Coordinate with the  applicable OSG-FPT prior to establishing or&#xA;revising runway designator numbers for an airport  having one or more&#xA;instrument approach or departure procedures, to determine the&#xA;appropriate MV to be applied to the runway true bearing. Determination&#xA;of the runway designator number should be a matter of joint agreement&#xA;with AeroNav Products, and be accomplished sufficiently in advance to&#xA;allow for procedural amendments. Take appropriate NOTAM action if&#xA;repainting of an affected runway has not been accomplished on the&#xA;required date.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;2-18. &lt;strong&gt;Guidelines&lt;/strong&gt;. The identification and selection of navigational&#xA;aids or airports as candidates for revision of MV of Record require&#xA;careful consideration and evaluation of a number of factors - as the&#xA;impact of MV changes can be considerable. The applicable Air Traffic&#xA;Service Area Office may have to initiate or revise published air&#xA;traffic procedures; the Technical Operations Service (AJW-0) is&#xA;directly involved in facility rotations and requires proper&#xA;coordination. The Airports Division, or appropriate military&#xA;authority, may have to arrange for repainting of runway designator&#xA;numbers [see paragraph 8-58e(2)(e)].&lt;/p&gt;&#xA;&lt;p&gt;a. MV versus Epoch Year Value. When the difference between the MV of&#xA;Record and the nearest future Epoch Year value of any navigational aid&#xA;or airport is 3 degrees or more, the MV of Record must be changed to&#xA;the nearest future Epoch Year value.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-07T05:51:25.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="660" PostTypeId="2" ParentId="243" CreationDate="2014-01-07T06:37:40.117" Score="4" Body="&lt;h1&gt;FARs on the web&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;There are several sites on the web, but my favorite is the FAA's own Regulatory and Guidance Library at &lt;a href=&quot;http://rgl.faa.gov/&quot; rel=&quot;nofollow&quot;&gt;http://rgl.faa.gov/&lt;/a&gt;.  If you click the &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameset&quot; rel=&quot;nofollow&quot;&gt;Code of Federal Regulations&lt;/a&gt; link on their main page, you can look at current &lt;strong&gt;&lt;em&gt;and historical regulations as well as preamble information, links to the dockets, NPRM's, and more&lt;/em&gt;&lt;/strong&gt;.  Just click on &quot;By Part&quot; under the &quot;Current CFR&quot; section, and you can browse through each section. If you then scroll down, you will find the two that you asked about:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Part 23 - AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Part 91 - GENERAL OPERATING AND FLIGHT RULES&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Click the arrow next to each part and it will show links to the full text of each regulation.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Extra Info&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The site also includes the following databases:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Advisory Circulars&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Draft Advisory Circulars&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Airworthiness Directives&#xA;&lt;ul&gt;&#xA;&lt;li&gt;AD NPRMs&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;CARs/CAMs/Aero-Bulletins&lt;/li&gt;&#xA;&lt;li&gt;Code of Federal Regulations&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CFR NPRMs&lt;/li&gt;&#xA;&lt;li&gt;CFR Final Rules&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Equivalent Levels of Safety&lt;/li&gt;&#xA;&lt;li&gt;Exemptions&lt;/li&gt;&#xA;&lt;li&gt;Orders/Notices&lt;/li&gt;&#xA;&lt;li&gt;Parts Manufacturer Approvals&lt;/li&gt;&#xA;&lt;li&gt;Policy&lt;/li&gt;&#xA;&lt;li&gt;Regulatory Basis Tool&lt;/li&gt;&#xA;&lt;li&gt;Special Airworthiness Information Bulletins&lt;/li&gt;&#xA;&lt;li&gt;Special Conditions&lt;/li&gt;&#xA;&lt;li&gt;Supplemental Type Certificates&lt;/li&gt;&#xA;&lt;li&gt;Technical Standard Orders and Index&lt;/li&gt;&#xA;&lt;li&gt;Type Certificate Data Sheets&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-07T06:37:40.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="661" PostTypeId="2" ParentId="654" CreationDate="2014-01-07T12:17:12.383" Score="50" Body="&lt;h2&gt;Fuel&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The fuel consumption of the A380 is about 11 metric tonnes per hour. With a fuel price of &lt;a href=&quot;http://www.iata.org/publications/economics/fuel-monitor/Pages/price-analysis.aspx&quot; rel=&quot;noreferrer&quot; title=&quot;IATA Fuel price table&quot;&gt;\$1000 per metric tonne&lt;/a&gt;, this results in \$11000 per flight hour. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Amortization&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An A380 will cost about \$350M. The aircraft will be used for about 25 to 30 years, but let's assume the amortization period is about 20 years with a residual value of \$50M. With an interest rate of 5%, you would pay about \$24M per year. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is about \$2740 per hour, or \$0.76 per second, flying or not. &#xA;Assuming a usage of  60%, taking into account turn around times at the gate and maintenance downtime,  it boils down to \$3915 per flight hour. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Crew&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Captain costs &lt;a href=&quot;http://www.askcaptainlim.com/salary-propilot-78/307-singapore-airlines-pilots-salary.html%20Singapore%20airlines%20salaries&quot; rel=&quot;noreferrer&quot;&gt;\$160K per year, the F/O \$90000&lt;/a&gt;. Let's assume they fly about 60 hours per month, the combined flight deck crew cost is about \$350 per flight hour for the base salary. Another \$80 needs to be added for allowances bringing the total to \$430 per flight hour. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin crew rate would be around $40 per hour, so for 20 crew the cost will be \$800 per flight hour.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also allowances for overnight stays and hotel costs need to be taken into account&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Airport charges&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These vary extremely between airports. You can basically break the costs down into costs related to the aircraft, the passengers and various taxes by the government. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft cost usually are related to the Maximum Take-off Mass (MTOM) of the aircraft and the noise category. A Boeing 747-400, while less heavy than an A380, will in some cases be more expensive due to the higher noise level. Many airports differentiate between peak and off-peak hour landings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find accurate data for the A380 but an old table that I have for the Boeing 747-400 suggest that total the cost vary between about \$6000 to \$25000. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Overflight charges&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Fees are levied by countries whose territory is flown over, mainly to cover ATC cost. The cost is typically based on the distance flown and the MTOW. For a 747-400ER over Europe, the fee is on average &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/publication/files/customer-guide-2014-version-8-0-with-coversheet.pdf&quot; rel=&quot;noreferrer&quot;&gt;145EUR per 100km&lt;/a&gt;. Assuming an average speed of about 900km/h, the hourly cost is about 1300EUR/h. These costs are lower over the high seas and over the US. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Rough total&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Based on the above, the total will be between \$22,000 and \$41,000 per hour.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-02-06T19:38:30.793" LastActivityDate="2017-02-06T19:38:30.793" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="662" PostTypeId="1" AcceptedAnswerId="10077" CreationDate="2014-01-07T12:50:37.013" Score="11" ViewCount="1736" Body="&lt;p&gt;If I recall, in America there were several &quot;Prohibited Access&quot; airspaces and others required permission, via radio, to enter in a typical aircraft. But, what if I'm gliding over a restricted airspace? (Say, over the Capitol?). Would I be shot down (or fined, sued, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="327" LastActivityDate="2014-12-08T18:13:37.010" Title="Can gliders access restricted airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;glider&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="663" PostTypeId="2" ParentId="662" CreationDate="2014-01-07T13:39:48.803" Score="5" Body="&lt;p&gt;It doesn't matter what category of aircraft that you are flying, the rules for restricted and prohibited airspace applies the same unless there is a specific exemption in a NOTAM for that, which I haven't seen before. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="3504" LastEditDate="2014-12-08T17:10:16.487" LastActivityDate="2014-12-08T17:10:16.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="664" PostTypeId="2" ParentId="662" CreationDate="2014-01-07T13:46:42.187" Score="5" Body="&lt;p&gt;As Inafziger has already said, there is no difference between a glider and a conventional airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;However&lt;/em&gt; it is possible to fly with both types of airplanes into all kinds of airspaces, if ATC granted the entry. In 99 per cent of the times they will require a transponder though, which only a few gliders have. (I think most aerobatic gliders have one)&lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-07T13:46:42.187" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="665" PostTypeId="1" AcceptedAnswerId="666" CreationDate="2014-01-07T13:47:29.333" Score="20" ViewCount="880" Body="&lt;p&gt;Looking at this video on &lt;a href=&quot;http://www.youtube.com/watch?v=Km2MA_hCCG0&quot; rel=&quot;noreferrer&quot;&gt;Youtube&lt;/a&gt;, I'm wondering if it is actually legal to take off with a windscreen iced like that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WN8mX.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For VFR this is a no go, but what about IFR and under what conditions?&lt;/p&gt;&#xA;" OwnerUserId="133" LastEditorUserId="72" LastEditDate="2014-03-03T05:25:27.590" LastActivityDate="2014-03-03T05:25:27.590" Title="Is it legal to take off with an iced windscreen?" Tags="&lt;faa-regulations&gt;&lt;preflight&gt;&lt;icing&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="666" PostTypeId="2" ParentId="665" CreationDate="2014-01-07T14:31:37.057" Score="15" Body="&lt;p&gt;When operating under Part 91, taking off with an iced windshield is not permitted. It does not differentiate between IFR and VFR operations.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.527 Operating in icing conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No pilot may take off an airplane that has frost, ice, or snow&#xA;  adhering to any propeller, windshield, stabilizing or control surface;&#xA;  to a powerplant installation; or to an airspeed, altimeter, rate of&#xA;  climb, or flight attitude instrument system or wing, except that&#xA;  takeoffs may be made with frost under the wing in the area of the fuel&#xA;  tanks if authorized by the FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now in the case that the winshield is simply covered in condensation (not ice), I'm not so sure about that, though it'd be pretty stupid to takeoff without heating the windshield and pretty much zero visibility for no particular reason. In that particular video though, that's definitely ice.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-07T14:43:22.897" LastActivityDate="2014-01-07T14:43:22.897" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="667" PostTypeId="1" AcceptedAnswerId="668" CreationDate="2014-01-07T14:41:40.117" Score="32" ViewCount="19599" Body="&lt;p&gt;I was watching Flight Radar 24, positioned near my house, to see what planes I could spot, and noticed a Cessna 550's transponder just dropped off @ 5,325 ft in a high-speed descent!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there something I should do about it? Or do I assume somebody in ATC has seen it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anything anyone should do in similar circumstances?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O3DF3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O3DF3.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-22T02:51:56.713" LastActivityDate="2014-03-22T02:51:56.713" Title="I just saw a plane drop off online radar; should I do anything about it?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="668" PostTypeId="2" ParentId="667" CreationDate="2014-01-07T14:51:19.840" Score="41" Body="&lt;p&gt;Really there's nothing you should do in cases like these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flightradar24, FlightAware, and similar services should not be used for flight safety purposes, and most of them specifically state so in their terms of service (such as sections 12 and 14 of &lt;a href=&quot;http://www.flightradar24.com/terms-and-conditions&quot;&gt;Flightradar24's terms and conditions&lt;/a&gt;). Their sources may go down for whatever reason -- that does not mean that the plane has crashed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These services can only track what ATC controllers can (for the most part), so it's more likely that if there is a real issue, that they'd notice without the general public making a fuss.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In this specific case the flight was being tracked using &lt;code&gt;MLAT&lt;/code&gt; (designated by the radar type &lt;code&gt;T-MLAT&lt;/code&gt;, which is shown in your animated image file). MLAT flight track accuracy relies on the accuracy and number of the receivers in the area, and according to Flightradar24's website, MLAT generally &lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot;&gt;only works above 10000 feet&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;MLAT&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;In some regions with coverage from several FR24-receivers we also&#xA;  calculate positions of aircraft with the help of Multilateration&#xA;  (MLAT), by using a method known as Time Difference of Arrival (TDOA).&#xA;  By measuring the difference in time to receive the signal from&#xA;  aircraft with an older ModeS-transponder, it's possible to calculate&#xA;  the position of these aircraft. Four FR24-receivers or more, receiving&#xA;  signals from the same aircraft, are needed to make MLAT work. That&#xA;  means that MLAT coverage can only be achieved above about 10000-20000&#xA;  feet as the probability that signal can be received by four or more&#xA;  receivers increases with increased altitude.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MLAT coverage is today limited to some parts of Europe and North&#xA;  America, but expanding fast.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So as the aircraft descends below 10,000 feet there is an increasing chance that you will lose it on Flightradar24's tracking system.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-08T04:56:02.070" LastActivityDate="2014-01-08T04:56:02.070" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="669" PostTypeId="2" ParentId="667" CreationDate="2014-01-07T14:54:18.603" Score="13" Body="&lt;p&gt;Nothing you should do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight Radar 24 does not have coverage down to ground level in all areas. ATC has better surveillance and will be aware of the aircraft. Probably it's just in a fast descent, the Citation II / Bravo is quite a nice toy. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-07T14:54:18.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="670" PostTypeId="1" AcceptedAnswerId="671" CreationDate="2014-01-07T15:50:46.177" Score="8" ViewCount="235" Body="&lt;p&gt;Are the broadcasters private individuals, governments, companies? Are they required to function 24/7 and if they don't, are the owners fined?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="69" LastEditDate="2014-01-13T01:54:28.613" LastActivityDate="2014-01-13T01:54:28.613" Title="Who's in charge of running VOLMET stations worldwide?" Tags="&lt;weather&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="671" PostTypeId="2" ParentId="670" CreationDate="2014-01-07T16:53:42.827" Score="1" Body="&lt;p&gt;This is an interesting question. According to the Air Navigation Plan of the ICAO (Part 6), all member countries have to broadcast these volmets, therefore it is extremely likely, that all Volmet stations are run by the government.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also states that this service has to be available all the time, but I doubt that fines are involved. There will be a Notam issued though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://aviadocs.net/icaodocs/Docs/9673_vol1_en.pdf&quot; rel=&quot;nofollow&quot;&gt;http://aviadocs.net/icaodocs/Docs/9673_vol1_en.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-07T16:53:42.827" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="673" PostTypeId="1" AcceptedAnswerId="681" CreationDate="2014-01-07T18:15:19.387" Score="30" ViewCount="48943" Body="&lt;p&gt;I've always wondered, what are those dual-layered (bonus: sometimes they have a little &amp;lt;2mm hole, why is it there?) windows commercial jets put next to their seats made of?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="1696" LastEditDate="2015-10-07T14:33:30.297" LastActivityDate="2017-11-11T09:47:35.520" Title="What materials are plane windows made of?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;windows&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="674" PostTypeId="5" CreationDate="2014-01-07T18:28:50.657" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-07T18:28:50.657" LastActivityDate="2014-01-07T18:28:50.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="675" PostTypeId="4" CreationDate="2014-01-07T18:28:50.657" Score="0" Body="Based in France, and with significant activity across Europe, the company produces approximately half of the world's jet airliners." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-11T18:11:55.137" LastActivityDate="2014-01-11T18:11:55.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="676" PostTypeId="5" CreationDate="2014-01-07T18:29:51.867" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-07T18:29:51.867" LastActivityDate="2014-01-07T18:29:51.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="677" PostTypeId="4" CreationDate="2014-01-07T18:29:51.867" Score="0" Body="A United States-based multinational corporation that designs, manufactures and sells fixed-wing aircraft, rotorcraft, rockets and satellites." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-11T18:11:51.777" LastActivityDate="2014-01-11T18:11:51.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="678" PostTypeId="2" ParentId="673" CreationDate="2014-01-07T18:32:48.347" Score="12" Body="&lt;p&gt;Windows are either made of acrylics (&lt;a href=&quot;https://en.wikipedia.org/wiki/Poly%28methyl_methacrylate%29&quot; rel=&quot;nofollow&quot;&gt;PMMA&lt;/a&gt;, brand name e.g. &quot;Plexiglas&quot;) or polycarbonate (&lt;a href=&quot;https://en.wikipedia.org/wiki/Polycarbonate&quot; rel=&quot;nofollow&quot;&gt;PC&lt;/a&gt;, &quot;Lexan&quot; or &quot;Makrolon&quot;) materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The small hole is there to provide ventilation and enable removal of moisture/condensation, but the hole is only in the thin protective screen on the inside. The much thicker actual window that holds the pressure is (hopefully) not punctured.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="1961" LastEditDate="2014-06-22T10:46:42.790" LastActivityDate="2014-06-22T10:46:42.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="679" PostTypeId="5" CreationDate="2014-01-07T18:33:19.977" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-07T18:33:19.977" LastActivityDate="2014-01-07T18:33:19.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="680" PostTypeId="4" CreationDate="2014-01-07T18:33:19.977" Score="0" Body="Avionics is applied electronics to aviation. Radars, radios, instruments, dashboards, they all belong to this category." OwnerUserId="327" LastEditorUserId="327" LastEditDate="2014-01-07T19:18:23.303" LastActivityDate="2014-01-07T19:18:23.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="681" PostTypeId="2" ParentId="673" CreationDate="2014-01-07T18:34:09.713" Score="27" Body="&lt;p&gt;Generally aircraft windows are made of what we colloquially call &quot;plexiglass&quot; of some kind (Lexan polycarbonate is common in light General Aviation aircraft, acrylic plastics are also used).  This material is light, relatively strong (not shatter-proof, but it'll take a moderate beating) and has decent optical properties.&lt;br&gt;&#xA;Its major drawback is &quot;crazing&quot; -- hairline cracks on the surface of the material that form over time from dirt, stress, temperature, UV exposure, and the like.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Bonus answer: The little hole serves a couple of purposes, but the biggie is pressure relief/equalization. &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/170548/&quot;&gt;This gets discussed over on airliners.net a lot&lt;/a&gt; and they've covered it pretty thoroughly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the hole ensures that the cabin pressure is pushing against the outer (primary, usually thicker) sheet of plexiglass, which is plug-wedged into the fuselage structure and can't go anywhere.&lt;br&gt;&#xA;Should the outer pane be damaged the hole will also theoretically bleed cabin pressure off at a controlled rate - though how successful that equalization is would depend on your altitude (and thus the pressure differential between the cabin and the outside air) and the degree of damage to the outer pane.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-07T18:34:09.713" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="682" PostTypeId="1" AcceptedAnswerId="683" CreationDate="2014-01-07T18:43:15.043" Score="21" ViewCount="21533" Body="&lt;p&gt;As far as I am concerned, FlightRadar24 reads out transponder responses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As most engine driven aircrafts have at least a mode C transponder, is there a site that displays such traffic as well?&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="97" LastEditDate="2014-04-03T04:05:07.087" LastActivityDate="2019-09-06T14:29:49.847" Title="Is there a website similar to FlightRadar24, but showing general aviation?" Tags="&lt;online-tracking&gt;&lt;website&gt;&lt;general-aviation&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="683" PostTypeId="2" ParentId="682" CreationDate="2014-01-07T18:56:52.780" Score="12" Body="&lt;p&gt;Yes, and no.&lt;br&gt;&#xA;FlightAware (and I believe FlightRadar24) will show General Aviation aircraft (I panned around a bit and found &lt;code&gt;N802AF&lt;/code&gt;, a Pilatus, buzzing around over Bethlehem, Pennsylvania just now).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The catch is most of these systems are fed with ATC data, and generally only pick up flights that are either on an instrument flight plan, or which have picked up flight following &amp;amp; been entered into the ATC system by the controller who set up the strip.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most light GA aircraft are flying around VFR (transponder code 1200), and don't show up on these flight tracking sites. Similarly if you're assigned a &quot;local&quot; transponder code rather than a system-wide one  you typically won't show up on the tracking sites either (this is often the case when you're flying VFR and go through Approach/Departure for Class C or Class B transitions/arrivals).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As more of the fleet is equipped with ADS-B this coverage may improve, as anyone can set up an ADS-B receiver and skim the traffic data. That data is currently only broadcast when a &quot;participating aircraft&quot; (ADS-B &lt;em&gt;Out&lt;/em&gt; equipped) is in the area though...&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-07T19:12:52.933" LastActivityDate="2014-01-07T19:12:52.933" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="684" PostTypeId="2" ParentId="595" CreationDate="2014-01-07T19:02:54.357" Score="7" Body="&lt;p&gt;In Europe, several national meteorological services provide additional info (sometimes on a paid basis). Some other services cater e.g. especially to glider pilots. Examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.flugwetter.de/&quot;&gt;http://www.flugwetter.de/&lt;/a&gt; ($)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dwd.de/bvbw/appmanager/bvbw/dwdwwwDesktop/?_nfpb=true&amp;amp;_pageLabel=_dwdwww_spezielle_nutzer_luftfahrt&amp;amp;T52801598661179816505191gsbDocumentPath=Navigation%2FLuftfahrt%2FPublic%2Fluftsportberichte__home__node.html%3F__nnn%3Dtrue&quot;&gt;DWD - Deutscher Wetterdienst Luftfahrt&lt;/a&gt;  (free)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.meteoschweiz.admin.ch/web/de/services/aviatik.html&quot;&gt;http://www.meteoschweiz.admin.ch/web/de/services/aviatik.html&lt;/a&gt; ($)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nzz.ch/wetter/thermikprognose/&quot;&gt;http://www.nzz.ch/wetter/thermikprognose/&lt;/a&gt; (free)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://wetter-jetzt.de/&quot;&gt;http://wetter-jetzt.de/&lt;/a&gt;  ($)&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are also a number of private websites run by clubs and/or enthusiast pilots, e.g. &lt;a href=&quot;http://www.schaenissoaring.ch/wetter_berichte.cfm?SelectedMenuID=154&quot;&gt;http://www.schaenissoaring.ch/wetter_berichte.cfm?SelectedMenuID=154&lt;/a&gt; or &lt;a href=&quot;http://www.alpenstreckenflug.de/wettera.htm&quot;&gt;http://www.alpenstreckenflug.de/wettera.htm&lt;/a&gt; which offer excellent (curated) information, sometimes on very special conditions like mountain waves etc..&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2014-01-07T19:09:18.943" LastActivityDate="2014-01-07T19:09:18.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="685" PostTypeId="2" ParentId="682" CreationDate="2014-01-07T19:16:26.253" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://flightaware.com&quot; rel=&quot;nofollow&quot;&gt;FlightAware&lt;/a&gt; picks up GA traffic, but only if it is on a flight plan (which sometimes includes VFR aircraft receiving flight following) or if the aircraft is &lt;a href=&quot;http://flightaware.com/adsb/&quot; rel=&quot;nofollow&quot;&gt;ADS-B Out equipped and within their ADS-B coverage areas&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, you're not currently going to get a full picture of the environment from any source - not in the way that ATC does, at least. Public sources aren't going to show the many, many aircraft not squawking unique codes.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-07T19:16:26.253" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="686" PostTypeId="1" AcceptedAnswerId="687" CreationDate="2014-01-07T19:19:40.617" Score="16" ViewCount="32175" Body="&lt;p&gt;If the center of gravity of an airplane is too far aft, it will become more unstable&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Iif the CG is too far forward, then drag will increase due to increased angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what are the benefits to operating with the CG near the aft, or forward, CG limits? In what situations would one choose to do so?&lt;/p&gt;&#xA;" OwnerUserId="16" LastEditorUserId="65" LastEditDate="2015-04-15T17:44:44.617" LastActivityDate="2015-04-15T21:09:36.267" Title="Are there advantages when operating with CG near forward or aft limits?" Tags="&lt;aircraft-performance&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="687" PostTypeId="2" ParentId="686" CreationDate="2014-01-07T19:27:56.117" Score="13" Body="&lt;p&gt;A CG near the aft reduces drag by reducing the necessary downforce that has to be supplied (usually) by the &lt;a href=&quot;https://aviation.stackexchange.com/q/439/95&quot;&gt;tailplane&lt;/a&gt;.&lt;br&gt;&#xA;This is also a point for competition gliding (more often than not you have water ballast in the vertical tailplane to compensate for those love handles). Aerobatic gliders sometimes feature aft lead ballast to enable maneuvers like tailspins which are not possible with a forward CG. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aft CGs come with reduced stability, which can be a severe flight-safety concern (e.g. in case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Spin_%28flight%29#Unrecoverable_spins&quot; rel=&quot;nofollow noreferrer&quot;&gt;unrecoverable spins&lt;/a&gt;).&lt;br&gt;&#xA;Some fighter aircraft feature inherently unstable aerodynamics (see &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermaneuverability#High_aerodynamic_maneuverability&quot; rel=&quot;nofollow noreferrer&quot;&gt;super-maneuverability&lt;/a&gt;) which offer great agility (e.g. turning rates), but need constant input by a flight constrol system (and woe if that &lt;a href=&quot;https://www.youtube.com/watch?v=o0Q0Qywyd_4&quot; rel=&quot;nofollow noreferrer&quot;&gt;fails&lt;/a&gt;, e.g. via &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilot-induced_oscillation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot Induced Oscillation&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A forward CG results in greater flight stability and reduced danger of sudden stalling, but also increased drag (because of the increased downforce required from the tailplane).  In extreme cases this can limit the maneuverability as well and cause a &lt;a href=&quot;http://www.merriam-webster.com/dictionary/pancake+landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;pancake landing&lt;/a&gt; (the tailplane can only produce so much lift/downforce before itself stalls, at which point it is no longer holding your nose up).&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-04-15T21:09:36.267" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="688" PostTypeId="2" ParentId="682" CreationDate="2014-01-07T20:01:13.170" Score="1" Body="&lt;p&gt;The remarkable &lt;a href=&quot;https://skylines.aero/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skylines project&lt;/a&gt; offers tracking based on data transmitted from your smartphone, e.g. using the great and free &lt;a href=&quot;http://www.xcsoar.org&quot; rel=&quot;nofollow noreferrer&quot;&gt;XCSoar&lt;/a&gt; software. Quite glider-centric, though.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2019-09-06T14:29:49.847" LastActivityDate="2019-09-06T14:29:49.847" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="689" PostTypeId="2" ParentId="686" CreationDate="2014-01-07T20:03:48.960" Score="8" Body="&lt;p&gt;The main benefit of operating with an aft CG, as mentioned, is that it can measurably reduce drag. This happens because less tail down force is required to maintain level flight in a given configuration. As a result, you can burn less fuel to maintain the same speed (or increase your speed for no additional fuel burn) compared to a forward CG. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you ensure you remain within your aircraft's CG envelope, you can test this out by having a passenger shift their seat aft while in cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are, of course, some safety concerns. @yankeekilo's answer covers this thoroughly, but if nothing else it should be reiterated that an aft cg is inherently less stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A forward CG makes recovery from stalls much easier, and in some cases can make stalls much harder to achieve because the moment-arm of your aircraft's CG changes. This change can leave the tailplane with insufficient input during slow flight, which is why you may never reach stall in the first place; it also makes landings dangerous as there may not be enough control range to flare. If this happens, you'll &lt;a href=&quot;http://www.youtube.com/watch?v=Eopl5QLQ5zs&quot;&gt;wheelbarrow or porpoise the aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-07T20:03:48.960" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="690" PostTypeId="2" ParentId="595" CreationDate="2014-01-07T20:05:46.743" Score="1" Body="&lt;p&gt;It's paid content but the weather briefs from &lt;a href=&quot;http://avwxworkshops.com/&quot; rel=&quot;nofollow&quot;&gt;http://avwxworkshops.com/&lt;/a&gt; are great.  I have used them to help take my light plane across the country twice.  Considering the importance of weather, I think membership is a good deal relative to the other costs of flying.  I'm not affiliated, just a happy customer.&lt;/p&gt;&#xA;" OwnerUserId="358" LastActivityDate="2014-01-07T20:05:46.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="691" PostTypeId="1" AcceptedAnswerId="699" CreationDate="2014-01-07T21:34:06.680" Score="18" ViewCount="41297" Body="&lt;p&gt;&lt;em&gt;(Related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/627/how-much-generally-speaking-does-it-cost-to-learn-how-to-fly&quot;&gt;this question&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many pilots have told me that an IFR rating is the most valuable thing i can do to improve my flying and margin of safety.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are courses as quick as, &quot;Get your IFR in 10 days!&quot;, but I'm unsure if that's  quality training that will stick with me.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How much should it cost for a robust, worthwhile IFR program for single engine land airplanes?&lt;br&gt;&#xA;What would distinguish a worthy program from one that merely meets minimums?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-08-27T02:18:14.863" Title="How much should it cost to get IFR-rated? What to look for?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;instrument-flight-rules&gt;&lt;cost&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="692" PostTypeId="5" CreationDate="2014-01-07T21:35:22.517" Score="0" Body="&lt;p&gt;General aviation - frequently abbreviated as GA - is a broad term that covers all civil aviation activities apart from scheduled, commercial passenger flights. This includes non-commercial recreational flying, but also commercial flights such as corporate jet transport, private charters for passengers or cargo, agricultural flights (crop dusting), aerial surveying, photography, air ambulances, firefighting and many other activities.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/General_aviation&quot; rel=&quot;nofollow&quot;&gt;General aviation&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-03-19T19:38:54.000" LastActivityDate="2015-03-19T19:38:54.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="693" PostTypeId="4" CreationDate="2014-01-07T21:35:22.517" Score="0" Body="General aviation (GA) includes all civil aviation activities except scheduled, commercial passenger flights. GA covers private recreational flying, corporate jet flights, flight training, crop dusting, aerial photography, and other activities." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-03-19T19:38:54.000" LastActivityDate="2015-03-19T19:38:54.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="694" PostTypeId="5" CreationDate="2014-01-07T21:49:27.110" Score="0" Body="&lt;p&gt;Instrument flight rules (IFR) is a set of regulations governing aircraft operations. IFR regulations allow a qualified pilot in a suitably equipped aircraft to fly and navigate using only instruments, without any visual reference outside the aircraft. IFR may be required because of weather conditions, airspace rules or for other reasons, but a pilot may choose to operate a flight under IFR even when there is no requirement to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR is usually contrasted with VFR (visual flight rules); all flights operate under either IFR or VFR. IFR should not be confused with IMC (instrument meteorological conditions), which are weather conditions in which IFR is required.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/IFR&quot; rel=&quot;nofollow&quot;&gt;IFR&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;nofollow&quot;&gt;IMC&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-07T22:21:41.570" LastActivityDate="2014-01-07T22:21:41.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="695" PostTypeId="4" CreationDate="2014-01-07T21:49:27.110" Score="0" Body="Instrument flight rules (IFR) is a set of regulations governing aircraft operations. IFR permits flying and navigating by instruments alone in conditions where there is no visual reference outside the aircraft." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-07T22:22:05.117" LastActivityDate="2014-01-07T22:22:05.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="696" PostTypeId="5" CreationDate="2014-01-07T22:00:25.713" Score="0" Body="&lt;p&gt;Visual flight rules (VFR) is a set of regulations governing aircraft operations. VFR regulations allow a pilot to fly and navigate by looking outside the aircraft and is permitted only when weather conditions are good enough to give the pilot a continuous view of the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some countries may allow VFR over the top, where a VFR flight temporarily loses visual contact with the ground as it flies over - but not into - cloud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VFR is usually contrasted with IFR (&lt;a href=&quot;/questions/tagged/instrument-flight-rules&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;instrument-flight-rules&amp;#39;&quot; rel=&quot;tag&quot;&gt;instrument-flight-rules&lt;/a&gt;); all flights operate under either VFR or IFR. VFR should not be confused with &lt;a href=&quot;/questions/tagged/vmc&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vmc&amp;#39;&quot; rel=&quot;tag&quot;&gt;vmc&lt;/a&gt; (visual meteorological conditions), which are weather conditions in which VFR is allowed.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_meteorological_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;VMC&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/VFR_over-the-top&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR over the top&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-03-25T05:55:28.657" LastActivityDate="2019-03-25T05:55:28.657" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="697" PostTypeId="4" CreationDate="2014-01-07T22:00:25.713" Score="0" Body="Visual flight rules (VFR) is a set of regulations governing aircraft operations. VFR permits flying and navigating by visual reference outside the aircraft." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-07T22:21:49.180" LastActivityDate="2014-01-07T22:21:49.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="698" PostTypeId="2" ParentId="606" CreationDate="2014-01-07T22:26:52.253" Score="23" Body="&lt;p&gt;In addition to the other answers, let´s look at this L/D(=E) diagram of the enticing &lt;a href=&quot;http://www.dg-flugzeugbau.de/technische-daten-1000-e.html&quot; rel=&quot;noreferrer&quot;&gt;DG-1000&lt;/a&gt; from DG Flugzeugbau (but fear not, 'tis true for all gliders) :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DUyHv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best L/D ratio is equal for different wing loadings, but is occuring at different speeds - the higher the load, the higher speed. You can also see that the minimum/stall speed is also higher for higher loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next diagram shows the &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_curve_%28aviation%29&quot; rel=&quot;noreferrer&quot;&gt;polar curve&lt;/a&gt;:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ZFmN6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that the minimum sink rate occurs at lightest load. The heavier the load, the longer you will have to circle in the same thermal for a given height gain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The loading is a tradeoff between higher average speed and less efficient climbing. In case of strong thermals and/or long glide intervals, the optimum moves toward more, in weak conditions towards less or no ballast. The good thing is that you can dump water rather quickly (also partially), so that in a competition you usually tend to fill up (and dump  in case) rather than start light (the &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Quintus&quot; rel=&quot;noreferrer&quot;&gt;Quintus&lt;/a&gt; e.g can take up to &lt;em&gt;250&lt;/em&gt; liters!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aft ballast in the vertical tailplane is sometimes used to balance a forward CG caused by water in the wings -  depending on your ship, partial dumping can be problematic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are many philosophies and tactical debates concerning the &quot;water or no water&quot; dispute, but once you´ve overtaken an identical, lighter ship with full wings and no height loss, you get to see how much fun ballast can be (until the next thermal, that is).&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2014-01-07T22:41:23.943" LastActivityDate="2014-01-07T22:41:23.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="699" PostTypeId="2" ParentId="691" CreationDate="2014-01-07T23:07:51.627" Score="8" Body="&lt;p&gt;The Part 141 flight school that I used to work at quoted around \$7,000 for their instrument package, which was 30 hours of dual flight, 20 hours of ground instruction, and 10 hours of PC-ATD simulator time. They were a Cessna Pilot Center using the old CPC King Schools course. It was a good course, and while numbers varied, I did have a couple of students who squeaked by right on the Part 141 course minimums. Other pilots added 5 to 10 hours more flight training into the mix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, my gut says that it should cost an average pilot who has 100+ hours and flies semi-regularly between \$7,000 and \$9,000; probably closer to the low end than the high end, especially if the student does a bunch of self study at home on a flight simulator, possibly using VATSim as a simulated ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as what to look for, I would recommend a Part 141 course just because the FAA is involved in the course standards, and instructor standardization is (supposed to be) part of the 141 criteria. It might be worth asking what their first-attempt pass rate is on checkrides, but that's not a meaningful long-term measure of the course's quality, just a short-term one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should find a course whose syllabus makes sense, includes simulator training and scenario-based flights, and make sure you work with an instructor you like. They can't be your best friend - they very well might need to give you some serious critique or cut a lesson short because things aren't going well - but you should be happy to spend a couple of hours a foot away from them in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'm trying to track down the average hours to attain an instrument rating in the US; if I find it, I'll update my answer.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="72" LastEditDate="2014-04-23T12:32:34.263" LastActivityDate="2014-04-23T12:32:34.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="700" PostTypeId="1" AcceptedAnswerId="706" CreationDate="2014-01-08T00:13:37.460" Score="41" ViewCount="20998" Body="&lt;p&gt;I'm not an aviator, I guess I'd call myself an enthusiast. I'm also a physics nut. I've always wondered about this but I equally worried my question posed to a commercial airline crew would land me in the Homeland Security Suites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On helicopters, torque along the vertical axis is countered by a smaller tail rotor (or a twin main rotor rotating in the opposite direction).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is whether the turbines/fans of multi-engine jet aircraft rotate in the same direction. I.e., do both the port engine and the starboard engine rotate uniformly clockwise or counterclockwise?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like if that were the case then maintenance might be easier but it would create some instability along the longitudinal axis of the airframe due to torque and moment arms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Follow up: I guess, then, that single engine propeller aircraft utilize trim presets to compensate for the longitudinal torque generated by their propeller–correct?&lt;/p&gt;&#xA;" OwnerUserId="363" LastEditorUserId="167" LastEditDate="2016-01-05T23:36:16.803" LastActivityDate="2017-09-27T22:31:57.353" Title="Do turbine engines on multi-engine aircraft rotate in opposite directions to offset torque?" Tags="&lt;jet-engine&gt;&lt;multi-engine&gt;&lt;turbine&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="701" PostTypeId="1" AcceptedAnswerId="703" CreationDate="2014-01-08T00:15:04.710" Score="41" ViewCount="85060" Body="&lt;p&gt;What are the advantages and disadvantages of a high-wing vs. low-wing aircraft design? When might one prefer one to the other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the answer the same for large and small aircraft?&lt;/p&gt;&#xA;" OwnerUserId="16" LastEditorUserId="65" LastEditDate="2015-03-12T18:54:47.007" LastActivityDate="2015-12-21T18:38:01.963" Title="What are the pros and cons of high-wing compared to low-wing design?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;" AnswerCount="9" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="702" PostTypeId="2" ParentId="682" CreationDate="2014-01-08T00:22:13.920" Score="1" Body="&lt;p&gt;You are right @Force the information presented on flightradar24.com are based on transponder outputs and completed with information stored in a database. Unfortunately a &quot;simple&quot; mode C or S is not sufficient for this. Flightradar24 gets its data not from ATC radars but from private suporters who run a receiver for so called ADS-B outputs from the aircraft. These are more advanced digital information then only the squawk, registration/callsign and altitude of an aircraft used by airliners. But more and more private owners use this technology and that's why you can look foreward to track more and more G/A traffic on flightradar24.com.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that flightaware.com also uses this data and additionally uses data provided by the FAA (with a five minute delay) as well. But you won't be able to track any aircraft with a VFR flight plan - unless he is ADS-B equipped - becuase in the US these flight plans are only used for SAR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A little additional remark: If you observe the German airspace at flightradar24.com you'll sometimes find some microlights on the 'scope' - sometimes I think these aircraft are 100kg aircraft and 250kg avionics.&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-08T00:22:13.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="703" PostTypeId="2" ParentId="701" CreationDate="2014-01-08T00:25:04.670" Score="35" Body="&lt;p&gt;This is actually a really hard question to answer, as there are a ton of factors. I'll try to cover a few.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Visibility&lt;/strong&gt; is probably the reason you most hear when it comes to GA pilots. &#xA;&lt;ul&gt;&#xA;&lt;li&gt;High-wing aircraft offer better visibility below the aircraft, especially for passengers in 4-seat or larger aircraft, as the wing doesn't block it. &lt;/li&gt;&#xA;&lt;li&gt;Low-wing aircraft can offer better visibility above the aircraft, as the wing remains mostly out of the field of view.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Note that a lot of midair collisions involve mixed types; low-wing aircraft descend into high-wing, or high-wing aircraft climb into low-wing.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Landing characteristics&lt;/strong&gt; are different, as low-wing aircraft can incur more ground effect than high-wing.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Aerodynamic stability&lt;/strong&gt; of the two designs differs a bit; the center of lift can be higher in a high-wing design, often offset with dihedral in low-wing aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Ground clearance&lt;/strong&gt; (and debris protection), specifically in multi-engine aircraft, is going to be greater when engines are mounted on a high wing rather than a low wing. This is true of both propeller and jet engines, although propellers tend to have a larger radius for a given aircraft size.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are a bunch more, but that ought to get the &lt;del&gt;argument&lt;/del&gt; discussion going.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-08T00:25:04.670" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="704" PostTypeId="2" ParentId="701" CreationDate="2014-01-08T00:39:13.653" Score="11" Body="&lt;p&gt;@Egid, your already gave really good and correct answer dealing with the most important benefits and downsides, or simple the most significant differences. I like to follow your invitation and add the differences I thought of and you have not already mentioned:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The additional ground clearance also benefits the maximum crosswind some high-wing aircraft can cope with,  what in my eyes is also an important point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also high wing aircraft - talking about light sports - benefit the design of the fuel system as it allows consumption from both tanks simultaneously without installation of additional fuel pumps - this is not only a benefit for lazy pilots but has probably already prevented some accidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now somebody needs to tell me why I'm flying low-wing ;)&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="5517" LastEditDate="2015-12-21T18:38:01.963" LastActivityDate="2015-12-21T18:38:01.963" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="705" PostTypeId="2" ParentId="642" CreationDate="2014-01-08T00:55:32.477" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;http://www.swc.state.nd.us/4dlink9/4dcgi/GetSubCategoryRecord/atmospheric%20resources/ND%20Cloud%20Modification%20Project&quot; rel=&quot;nofollow&quot;&gt;North Dakota State Water Commission&lt;/a&gt; runs the North Dakota Cloud Modification Project, which primarily seems to work at reducing hail damage to crops during the thunderstorm season, and has been active (perhaps not continuously) since 1975.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They've got a &lt;a href=&quot;http://www.swc.state.nd.us/4dlink9/4dcgi/GetContentRecord/PB-292&quot; rel=&quot;nofollow&quot;&gt;section on program evaluations&lt;/a&gt;; a peer-reviewed article published in 1997 states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] the expanded 13-year NDCMP data base showed a 45% decrease in losses in the target area (Smith, et al., 1997).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Their website has a ton of information; a company called &lt;a href=&quot;http://www.weathermodification.com/projects.php&quot; rel=&quot;nofollow&quot;&gt;Weather Modification, Inc.&lt;/a&gt; is the contractor for ND State and does a lot of other work as well. Either the state or WMI would probably be able to provide additional data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may also be worth noting that Russia does lots of weather modification work as well (perhaps more when it was the Soviet Union). No idea how successful any of it is.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-08T00:55:32.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="706" PostTypeId="2" ParentId="700" CreationDate="2014-01-08T01:24:12.560" Score="31" Body="&lt;p&gt;Engines on airliners turn the same direction. The torque isn't as much an issue on jets as it is on props.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of multiengine prop planes have propellers that turn in opposite directions. In turbine engines this can be done in a gearbox to allow the same engine to be used on both sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some turbine engines, such as the PT6, have two turbines turning in opposite directions, but the propeller friction produces additional torque in one direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Single engine planes sometimes have the engine mounted at a slight angle to reduce the effect of the propwash (and maybe torque?). The propwash causes imbalance at low speed and high power when the descending blade tends to push air down over the wing on that side, and and vice versa for the ascending blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Immediately after takeoff, the rudder of a single engine plane is normally depressed, to some extent, to make up for the uneven torque and propwash. This may be done manually, with trim settings, or both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher speeds, the effect of the propeller torque is not as noticeable because the wings are held &quot;more tightly&quot; by the airflow.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-01-08T01:24:12.560" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="707" PostTypeId="5" CreationDate="2014-01-08T02:23:21.580" Score="0" Body="&lt;p&gt;Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aerospace study and engineering, including aircraft design and performance calculations. Pilots are usually taught at least some basic aerodynamic principles as part of their training, depending on their level of certification. Aerodynamics also has many applications outside the field of aviation, such as in automotive design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for questions about lift, drag, airfoil efficiency. It is not appropriate for performance questions that are specifically about engines or other non-aerodynamic aircraft components.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aerodynamics&quot; rel=&quot;nofollow&quot;&gt;Aerodynamics&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-09T21:35:20.093" LastActivityDate="2014-01-09T21:35:20.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="708" PostTypeId="4" CreationDate="2014-01-08T02:23:21.580" Score="0" Body="Aerodynamics is the study of how air moves and interacts with solid objects. It is an essential part of aircraft design." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-09T21:35:07.957" LastActivityDate="2014-01-09T21:35:07.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="709" PostTypeId="5" CreationDate="2014-01-08T02:25:11.510" Score="0" Body="&lt;p&gt;Takeoff is when an aircraft lifts off the ground and is the first phase of flight. Takeoff techniques vary depending on the aircraft and the runway or other surface, but a typical takeoff in an &lt;a href=&quot;/questions/tagged/airplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;airplane&lt;/a&gt; has four stages: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lining up (or positioning): taxiing onto the runway and lining up with the centerline&lt;/li&gt;&#xA;&lt;li&gt;Rolling: applying power and increasing speed to the point where the aircraft is creating enough lift to fly&lt;/li&gt;&#xA;&lt;li&gt;Rotation: lifting the nose of the aircraft to initiate the actual lift-off from the ground&lt;/li&gt;&#xA;&lt;li&gt;Climb-out: climbing to an initial minimum altitude before making any maneuvers such as turning&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aircraft always take off into the &lt;a href=&quot;/questions/tagged/wind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wind&amp;#39;&quot; rel=&quot;tag&quot;&gt;wind&lt;/a&gt; if possible, because it reduces the groundspeed required to become airborne; e.g. if an aircraft requires an airspeed of 60 knots to take off and there is a headwind of 20 knots then the groundspeed at takeoff is reduced to 40 knots. A lower groundspeed at takeoff means that the aircraft can lift off sooner, requiring less runway, and also means that less braking is required in the event of a &lt;a href=&quot;/questions/tagged/rejected-takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rejected-takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;rejected-takeoff&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A departing aircraft lines up on the runway centerline before beginning the takeoff roll, to make sure that in case of crosswinds or control issues there is maximum space available on both sides of the aircraft.  The aircraft may start rolling immediately or it may wait on the runway before starting the roll (in an ATC environment, the pilot may be instructed to &quot;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;line up and wait&lt;/a&gt;&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The takeoff roll begins when the aircraft starts accelerating to reach takeoff speed. The required speed can vary depending on the aircraft's configuration (e.g. with or without flaps). When the aircraft reaches takeoff speed, the pilot rotates (lifts the nose) to start the actual flight. Larger aircraft also have a &quot;decision speed&quot; referred to as &lt;a href=&quot;http://en.wikipedia.org/wiki/V_speeds#V1_definitions&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;&lt;/a&gt;, where the aircraft is not yet able to rotate but has passed the point where it is still possible to abort the takeoff in the remaining runway length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After rotation the aircraft starts its initial climb and during this phase of takeoff the pilot configures the aircraft for the climb by setting an appropriate airspeed, retracting flaps and undercarriage (if applicable) and performing any other required actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Takeoffs in a &lt;a href=&quot;/questions/tagged/helicopter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helicopter&amp;#39;&quot; rel=&quot;tag&quot;&gt;helicopter&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/balloon&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;balloon&amp;#39;&quot; rel=&quot;tag&quot;&gt;balloon&lt;/a&gt;, or other special aircraft types require different techniques, and all aircraft may require special takeoff procedures for specific conditions such as short runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for all questions about takeoff techniques and procedures, legal regulations on takeoffs and so on.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Takeoff&quot; rel=&quot;nofollow noreferrer&quot;&gt;Takeoff&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/V_speeds&quot; rel=&quot;nofollow noreferrer&quot;&gt;V speeds&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8282" LastEditorUserId="22726" LastEditDate="2019-09-26T14:01:17.577" LastActivityDate="2019-09-26T14:01:17.577" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="710" PostTypeId="4" CreationDate="2014-01-08T02:25:11.510" Score="0" Body="Takeoff is the first phase of flight, when an aircraft lifts off from the runway or other surface." OwnerUserId="327" LastEditorUserId="22726" LastEditDate="2019-09-27T00:01:17.483" LastActivityDate="2019-09-27T00:01:17.483" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="711" PostTypeId="5" CreationDate="2014-01-08T02:27:36.053" Score="0" Body="&lt;p&gt;The Civil Aviation Authority of the USA is the Federal Aviation Administration &lt;a href=&quot;/questions/tagged/faa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'faa'&quot; rel=&quot;tag&quot;&gt;faa&lt;/a&gt; / &lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'faa-regulations'&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="19" LastEditDate="2015-04-02T17:56:08.800" LastActivityDate="2015-04-02T17:56:08.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="712" PostTypeId="4" CreationDate="2014-01-08T02:27:36.053" Score="0" Body="Use this tag for questions which are specific to the United States, but not regulatory in nature. For questions about aviation regulations in the US, use the faa-regulations tag." OwnerUserId="327" LastEditorUserId="6" LastEditDate="2014-04-11T03:13:47.143" LastActivityDate="2014-04-11T03:13:47.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="713" PostTypeId="2" ParentId="382" CreationDate="2014-01-08T02:29:44.827" Score="6" Body="&lt;p&gt;Since no-one has answered this yet, I'll give it a crack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.usai.in/regulations.html&quot;&gt;Unmanned Systems Association of India&lt;/a&gt;, UAVs are required to submit a specific request to the Directorate General of Civil Aviation to allow them to fly UAVs in a specific area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For RC aircraft, you must make sure that they use one of the following frequencies (&lt;a href=&quot;http://articles.timesofindia.indiatimes.com/2009-07-31/india/28208731_1_frequency-planes-customs&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;27004 KHz&lt;/li&gt;&#xA;&lt;li&gt;27116 KHz&lt;/li&gt;&#xA;&lt;li&gt;27148 KHz&lt;/li&gt;&#xA;&lt;li&gt;27156 KHz&lt;/li&gt;&#xA;&lt;li&gt;27228 KHz&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm not so sure about what makes an aircraft in the RC category, as opposed to an UAV though -- if someone could fill me in on that, that'd be great.&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-01-08T02:29:44.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="714" PostTypeId="5" CreationDate="2014-01-08T02:43:00.187" Score="0" Body="&lt;p&gt;METAR weather reporting format is used by aviation weather stations for routine weather reporting (typically hourly). The information contained in a METAR report includes the location of the weather station, date &amp;amp; time of the weather observation, the wind speed &amp;amp; direction, visibility, precipitation, cloud cover, temperature, and barometric pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar, but distinct, type of weather information report is &lt;a href=&quot;https://aviation.stackexchange.com/tags/taf&quot;&gt;TAF, or Terminal Area Forecast&lt;/a&gt;, which provides a forecast rather than the most recently available information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical US METAR observation looks like this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;METAR KTTN 051853Z 04011KT 4SM -SN BKN050 OVC100 02/M02 A3006 RMK AO2&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Decoded:&lt;br&gt;&#xA;This is a routine hourly report (&lt;code&gt;METAR&lt;/code&gt;) at Trenton-Mercer Airport (&lt;a href=&quot;http://www.airnav.com/airport/KTTN&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;code&gt;KTTN&lt;/code&gt;&lt;/a&gt;).&lt;br&gt;&#xA;The observation was taken on the 5th of this month, at 1853 UTC (&lt;code&gt;051853Z&lt;/code&gt;).&lt;br&gt;&#xA;The winds were from 040°, at 11 knots (&lt;code&gt;04011KT&lt;/code&gt;).&lt;br&gt;&#xA;Ground-level visibility was 4 statute miles (&lt;code&gt;4SM&lt;/code&gt;), with light snow falling (&lt;code&gt;-SN&lt;/code&gt;).&lt;br&gt;&#xA;There was a broken cloud layer at 5000 feet (&lt;code&gt;BKN040&lt;/code&gt;, and an overcast layer at 10000 feet (&lt;code&gt;OVC100&lt;/code&gt;).&lt;br&gt;&#xA;The temperature was 2° Celsius, and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dew_point&quot; rel=&quot;nofollow noreferrer&quot;&gt;dew point&lt;/a&gt; was -2° Celsius (&lt;code&gt;02/M02&lt;/code&gt;).&lt;br&gt;&#xA;The barometric pressure (altimeter setting) was 30.06 inches of mercury (&lt;code&gt;A3006&lt;/code&gt;).&lt;br&gt;&#xA;There are remarks (comments, following&lt;code&gt;RMK&lt;/code&gt;), which in this case specify the type of weather station equipment that generated the report.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Detailed information on METARs, including a reference for decoding the information, can be found &lt;a href=&quot;http://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;on Wikipedia&lt;/a&gt;, as well as through a variety of other sources.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="14897" LastEditDate="2018-02-24T13:51:19.573" LastActivityDate="2018-02-24T13:51:19.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="715" PostTypeId="4" CreationDate="2014-01-08T02:43:00.187" Score="0" Body="METAR is a format for reporting the latest available weather information. It is similar to but distinct from TAF." OwnerUserId="327" LastEditorUserId="753" LastEditDate="2018-02-24T18:48:54.877" LastActivityDate="2018-02-24T18:48:54.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="716" PostTypeId="1" AcceptedAnswerId="717" CreationDate="2014-01-08T02:48:46.867" Score="22" ViewCount="18355" Body="&lt;p&gt;When designing an aircraft, there has to be a decision as to the aspect ratio of a wing. It's been said that having a higher aspect wing will reduce drag for the same wing area, however most of the time wings are shorter than they can be. So my question is, what exactly dictates the aspect ratio of a wing, and why don't they make them as long as possible?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2019-05-18T20:58:46.783" Title="What dictates the aspect ratio of an aircraft's wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="717" PostTypeId="2" ParentId="716" CreationDate="2014-01-08T03:16:23.800" Score="10" Body="&lt;p&gt;&lt;strong&gt;Aspect ratio&lt;/strong&gt; is the ratio based on the span and chord of an aircraft's wings. The &lt;em&gt;span&lt;/em&gt; is the length of the wings measured wingtip to wingtip; the &lt;em&gt;chord&lt;/em&gt; is the 'depth' of the wing from the leading edge to the trailing edge, measured in a straight line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because very few aircraft have constant chord planforms, this requires a not-very-fancy formula to calculate (&lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/geom.html&quot; rel=&quot;noreferrer&quot;&gt;source: NASA&lt;/a&gt;), so that we can effectively average the chord:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$AR=\frac{b^2}{S}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$AR=$ Aspect ratio&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$B=$ Wingspan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$S=$ Wing's area&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Math aside, aspect ratio is chosen based on an aircraft's role or requirements. A need for agility dictates a low aspect ratio, as does a need for compactness. In both cases, fighter aircraft and bush aircraft benefit from agility and small size. High aspect ratios provide great cruise efficiency but can have poor landing characteristics (high drag at low speeds or high angles of attack due to frontal area) that are often offset by high-lift devices like flaps and slats.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the second half of your question: even when a high aspect ratio is desired, wings are not made as long as possible for two reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first is structural; the bending forces associated with wings of extreme length are, well, extreme, and the materials required are pretty space-age. See high-performance gliders, or at the crazy end, solar- or human-powered aircraft, for examples of this. It's just hard to do at the size of an airliner. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second reason is more practical: space is expensive. An extremely high-aspect ratio wing takes up a ton of space relative to the rest of the aircraft. In an attempt to offset this, early 777s (which had a larger span than 767s and 747s) were offered with folding wingtips, but nobody bought that option and it got dropped.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="97" LastEditDate="2014-04-17T02:00:46.063" LastActivityDate="2014-04-17T02:00:46.063" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="718" PostTypeId="1" AcceptedAnswerId="721" CreationDate="2014-01-08T03:32:24.257" Score="13" ViewCount="818" Body="&lt;p&gt;In doing some planning for an upcoming flight, I noticed my destination (a towered airport) has a NOTAM about the runway: &quot;FICON PATCHY ICE&quot;. That seems rather vague, I'd like more information before departing. Who should I contact to get more details about the runway conditions and how it might affect my flight?&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="97" LastEditDate="2014-01-13T01:16:13.670" LastActivityDate="2014-01-13T01:16:13.670" Title="How can I get more details about information in a NOTAM?" Tags="&lt;flight-planning&gt;&lt;airport&gt;&lt;notam&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="719" PostTypeId="2" ParentId="691" CreationDate="2014-01-08T03:33:14.387" Score="3" Body="&lt;p&gt;Unfortunately I don't have the full details any more of what I paid when I did my part 61 IR, but from what I can remember the costs are similar to the ones I &lt;a href=&quot;https://aviation.stackexchange.com/questions/627/how-much-generally-speaking-does-it-cost-to-learn-how-to-fly/633#633&quot;&gt;listed&lt;/a&gt; in the other question you mentioned:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft rental&lt;/li&gt;&#xA;&lt;li&gt;Instructor time (air and ground)&lt;/li&gt;&#xA;&lt;li&gt;Materials (books, DVDs, charts, hood, timer etc.)&lt;/li&gt;&#xA;&lt;li&gt;Written test fee&lt;/li&gt;&#xA;&lt;li&gt;Examiner's fee for the actual test&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If we assume a part 61 instructor (\$40/hr) and an IFR-capable rented aircraft (\$130/hr wet) then we come out with something like this (you need a minimum of 40 hours instrument time):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;45 flying hours with instructor: \$7650&lt;/li&gt;&#xA;&lt;li&gt;15 hours ground school (instruction and simulator time): \$600&lt;/li&gt;&#xA;&lt;li&gt;Materials: \$600&lt;/li&gt;&#xA;&lt;li&gt;Written test fee: \$150&lt;/li&gt;&#xA;&lt;li&gt;DPE test fee: \$400 (plus \$130 rental for the aircraft)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Total: \$9530&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that under part 61 you also need to have 50 hours cross-country PIC time, which I didn't include in this calculation. And I increased the materials cost slightly here, because IR materials seem to be more expensive than private pilot ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Key factors to consider are the instructor (as with any training) and the aircraft. A good instructor will help make sure things stick in your mind, even if the training is accelerated. I required 49.6 dual hours for my IR according to my logbook, but that was spread out over 10 months and I could certainly have reduced it by flying more often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the aircraft, it's important to think about which aircraft you'll use your IR in, because training on a glass panel will probably be \$20+/hr more expensive than on 'steam gauges'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, you can make a lot of use of PC simulators like Microsoft Flight Simulator to practice instrument flight at home, which will be a lot cheaper than doing it in the air and it's surprisingly effective. Your FBO or flight school might have something more advanced, of course. And self-study in general will cut down on the ground school time you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no experience of part 141 or accelerated courses, so I can't say anything useful about those options but I would certainly research them if I was considering an IR. &quot;Worthy&quot; is a fairly subjective thing, but you can always ask around for recommendations, speak to previous students and so on.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-04-23T12:33:21.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="720" PostTypeId="2" ParentId="718" CreationDate="2014-01-08T03:43:43.040" Score="0" Body="&lt;p&gt;In such a case the best action would be to call the tower's published telephone number. They will have more information regarding this notam (and might even have created it themselves) .&lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-08T03:43:43.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="721" PostTypeId="2" ParentId="718" CreationDate="2014-01-08T03:45:44.520" Score="12" Body="&lt;p&gt;What, you dislike the fact that the NOTAM about patchy ice is patchy in its detail? :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally if you need more information about a NOTAM (in the US) you can check with:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Flight Service&lt;/strong&gt;&#xA;While collecting your briefing ask if they have any more detail -- sometimes they do, sometimes they don't, but it's worth asking.  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;A local FBO&lt;/strong&gt;&lt;br&gt;&#xA;Particularly for &lt;code&gt;FICON&lt;/code&gt; NOTAMs - A local FBO will usually know the condition of the field, and often have other useful info for you (like how much a heated hangar is going to cost you for the night).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Airport Operations&lt;/strong&gt;&lt;br&gt;&#xA;Again, particularly for &lt;code&gt;FICON&lt;/code&gt; NOTAMs - These guys will usually have a pretty good picture of the field's condition, since they're generally the poor shmucks responsible for doing the snow/ice clearing.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Failing all of those, you can also call the tower phone number at a towered field (you can get that number from Flight Service too) and ask them for details.&lt;br&gt;&#xA;I usually make the tower my last resort call - they're almost certainly going to be willing to give you as much information as they can, but they're also busy doing other stuff like dealing with planes taking off/landing/taxiing around &amp;amp; they'd probably appreciate if we tried the other sources first.&lt;br&gt;&#xA;The other folks I mentioned generally have someone sitting around to answer phones and questions.&lt;br&gt;&#xA;In the case of Flight Service, that's basically their job :-)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-08T03:45:44.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="722" PostTypeId="2" ParentId="718" CreationDate="2014-01-08T03:46:54.587" Score="4" Body="&lt;p&gt;Well this NOTAM really doesn't give a good impression of what's the actual condition is, but I appreciate you being keen to get some detailed information prior getting there. You should consider to call the airport manager - find the number e.g. at skyvector, but I wouldn't wait until the date of your departure, as these people are sometimes not easy to contact and it needs several tries, but of cause the information, especially regarding this NOTAM,  should be as up to date as possible. A local FBO could also provide you with some more detailed information. &lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-08T03:46:54.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="723" PostTypeId="2" ParentId="716" CreationDate="2014-01-08T04:19:08.780" Score="4" Body="&lt;p&gt;To answer your question it's maybe helpful to remember why a higher aspect ratio generates less drag. A higher aspect ratio causes less induced drag at the same lift than an aerofoil with a lower aspect ratio. Okay, we need a certain amount of lift and our aim is to gain this lift as efficient as possible. Lets do it: Higher aspect ratio -&gt; less drag, less drag less fuel burn, less fuel burn -&gt; higher efficiency - perfect, but there are maybe other ways to reduce drag and safe for example space, or weight - a longer leading edge creates more form drag and where do you park this giant aircraft and it means a lot of weight to get sufficient strength for this giant wing - weight needs lift to fly and more lift causes more drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Okay, I think it's clear now, that it's not sufficient to consider only one way of tuning the efficiency of your aircraft. There are also nice possibilities like winglets to reduce induced drag for only a little extra weight and also just a little extra interference drag or a good range of possible CGs which requires left negative lift on the tail = less lift required at the wing. New materials and design techniques also allow to work on the all in all shape of the wing which increases the efficiency rapidly.  Building a good aircraft is finding a good balance and so you can't just concentrate on only one possible solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope my wired talk can help you a little bit, sorry I fly this stuff and I guess all my colleagues are happy that I don't build it ;)&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="72" LastEditDate="2014-01-08T04:34:17.990" LastActivityDate="2014-01-08T04:34:17.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="724" PostTypeId="2" ParentId="700" CreationDate="2014-01-08T04:42:51.777" Score="11" Body="&lt;p&gt;Let's give a short and snappy answer regarding jets: it's all about efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a part of an engine is damaged then the engine will most likely be replaced and repaired while the aircraft is flying with another engine. An engine turning clockwise and an engine turning counterclockwise are two different engines. Let's do some simple economics now: is it more efficient to have only one extra engine you can use regardless of which engine failed or if you need an extra engine for each side? Clearly the most economical maintenance solution is to ensure both jets, regardless of the side of the airframe they attach to, are identical and thus interchangeable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking as someone who's not a scientist, the torque effect at jet engines indeed is negligible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about props? The biggest factor affecting props is that an ascending blade  delivers less lift (in forward direction) than the descending blade. If you now chose two engines both turning in the same direction and attach these to the wings of an aircraft, one side has the descending blade outboard and on the other side it will be inboard - now you have a critical engine. If the engine where the descending blade is inboard (critical engine) fails, it creates a greater yaw than if the other engine fails. Now you need to evaluate if safety and structural design allow you to have two engines turning in the same direction.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="363" LastEditDate="2014-01-09T03:51:30.700" LastActivityDate="2014-01-09T03:51:30.700" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="725" PostTypeId="5" CreationDate="2014-01-08T05:32:56.093" Score="0" Body="&lt;p&gt;A &lt;strong&gt;glider&lt;/strong&gt; is an aircraft that is designed to be operated in unpowered flight. They typically have long, high-aspect-ratio wings, and are lightweight compared to powered aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sailplanes&lt;/em&gt; have no internal propulsion and can be towed aloft by tow planes or launched using ground-based winches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some types, occasionally referred to as &lt;em&gt;self-launching gliders&lt;/em&gt; or &lt;em&gt;motorgliders&lt;/em&gt;, have propulsion systems, but they generally only use their engines to reach a point at which they can begin gliding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Hang gliders&lt;/em&gt; are minimal fabric-and-tube, delta-winged gliders launched on foot and typically steered by shifting the pilot's weight. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-08T13:56:44.610" LastActivityDate="2014-01-08T13:56:44.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="726" PostTypeId="4" CreationDate="2014-01-08T05:32:56.093" Score="0" Body="Use for gliders; combine with specific tags, e.g. [sailplane], if required." OwnerUserId="39" LastEditorUserId="14897" LastEditDate="2021-04-22T16:55:17.490" LastActivityDate="2021-04-22T16:55:17.490" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="727" PostTypeId="5" CreationDate="2014-01-08T06:36:43.687" Score="0" Body="&lt;p&gt;A crosswind is wind blowing across the direction of travel of an aircraft (as opposed to a headwind, or a tailwind).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rndnc.gif&quot; alt=&quot;Illustration of wind direction in tailwind, headwind, and crosswind&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A crosswind may be a direct crosswind (blowing at exactly 90 degrees to the aircraft's direction of travel as shown above), or a wind blowing at an angle to the direction of travel (a headwind/tailwind with a &lt;em&gt;crosswind component&lt;/em&gt;, which can be calculated using a &lt;a href=&quot;https://i.stack.imgur.com/2xcio.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;crosswind component grid&lt;/a&gt;; such a wind is also known as a &lt;em&gt;quartering headwind/tailwind&lt;/em&gt;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2019-09-20T23:37:55.503" LastActivityDate="2019-09-20T23:37:55.503" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="728" PostTypeId="4" CreationDate="2014-01-08T06:36:43.687" Score="0" Body="A crosswind is wind blowing across the direction of travel of an aircraft (as opposed to a headwind or tailwind)." OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2019-09-20T23:38:11.187" LastActivityDate="2019-09-20T23:38:11.187" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="729" PostTypeId="5" CreationDate="2014-01-08T06:52:09.170" Score="0" Body="&lt;p&gt;A stall is an aerodynamic condition wherein the angle of attack of a wing increases beyond the &quot;critical angle of attack&quot;, causing the wing to cease generating lift. It's important to note that stalls can happen at any airspeed and in any attitude; the only cause of a stall is exceeding the critical angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the angle of attack of a wing increases it generates more lift, up until the &lt;em&gt;critical angle of attack&lt;/em&gt;. Increasing the angle of attack beyond the critical angle results in a turbulent, detached airflow along the top of the wing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CV2Df.jpg&quot; alt=&quot;Stall diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point the wing is no longer generating lift, and the angle of attack must be reduced to allow the wing to produce lift again.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For more information about aerodynamic stalls and recovery &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_(flight)&quot; rel=&quot;nofollow noreferrer&quot;&gt;see the Wikipedia article&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="62" LastEditDate="2015-05-14T15:13:20.363" LastActivityDate="2015-05-14T15:13:20.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="730" PostTypeId="4" CreationDate="2014-01-08T06:52:09.170" Score="0" Body="A stall is an aerodynamic condition wherein the angle of attack of a wing increases beyond the &quot;critical angle of attack&quot;, causing the wing to cease generating lift." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-08T13:56:00.250" LastActivityDate="2014-01-08T13:56:00.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="731" PostTypeId="5" CreationDate="2014-01-08T07:02:10.220" Score="0" Body="&lt;p&gt;A turboprop engine is a type of turbine engine which drives an aircraft &lt;a href=&quot;/questions/tagged/propeller&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;propeller&amp;#39;&quot; rel=&quot;tag&quot;&gt;propeller&lt;/a&gt; to produce thrust (as opposed to a &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;, where the turbine exhaust provides thrust directly). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turboprop engines are very efficient at speeds below 390 knots, and are often found on smaller &quot;commuter&quot; aircraft, where the superior reliability of turbine engines (compared to &lt;a href=&quot;/questions/tagged/piston-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;piston-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;piston-engine&lt;/a&gt;s) and the efficiency of propellers for generating thrust make them an economically attractive choice.  (Very small &lt;a href=&quot;/questions/tagged/general-aviation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;general-aviation&amp;#39;&quot; rel=&quot;tag&quot;&gt;general-aviation&lt;/a&gt; aircraft still tend to use piston engines, as turboprops don't scale down to very small sizes particularly well.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Turboprop&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia for more on turboprops.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2019-05-27T04:30:34.543" LastActivityDate="2019-05-27T04:30:34.543" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="732" PostTypeId="4" CreationDate="2014-01-08T07:02:10.220" Score="0" Body="A turboprop engine is a type of turbine engine which drives an aircraft propeller to produce thrust (as opposed to a jet engine, where the turbine exhaust provides thrust directly).&#xD;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-08T13:54:38.883" LastActivityDate="2014-01-08T13:54:38.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="733" PostTypeId="5" CreationDate="2014-01-08T07:24:01.500" Score="0" Body="&lt;p&gt;The E6B is a &quot;flight computer&quot; designed to perform common aviation calculations, such as &quot;How much fuel will be burned in 3 hours in cruise flight?&quot; or &quot;How long will it take to travel 248 nautical miles at a speed of 132 knots?&quot;, conversions such as quantity of fuel (liters or gallons) to weight (kilograms or pounds), and calculating the effects of wind on cruise flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The traditional E6B is a mechanical slide rule, as shown below, however electronic E6B calculators are available, and E6B functionality is often incorporated into other aviation applications like weight &amp;amp; balance calculators or flight planning software.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/1DrwE.jpg&quot; alt=&quot;Mechanical E6B&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an example of how to use a mechanical E6B &lt;a href=&quot;http://www.youtube.com/watch?v=chVB8jvHw8Q&quot; rel=&quot;nofollow noreferrer&quot;&gt;see this YouTube video&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-08T13:59:28.997" LastActivityDate="2014-01-08T13:59:28.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="734" PostTypeId="4" CreationDate="2014-01-08T07:24:01.500" Score="0" Body="The E6B is a &quot;flight computer&quot; designed to perform common aviation calculations during flight planning, or in-flight." OwnerUserId="-1" LastEditorUserId="64" LastEditDate="2016-06-28T05:27:39.007" LastActivityDate="2016-06-28T05:27:39.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="735" PostTypeId="1" AcceptedAnswerId="737" CreationDate="2014-01-08T07:43:05.243" Score="27" ViewCount="7778" Body="&lt;p&gt;Turbine engines are covered, which of course is to contain the process (just like a super/turbocharged engine is as soon as the air enters the intake). But it got me thinking, doesn't this also reduce - or even completely remove - the induced drag around the tips of the fan blades?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be possible to have a similar setup for a standard prop, it doesn't even have to be stationary, it could be a ring connecting the tips of the prop, spinning with it, like an infinite winglet.  It has the added safety benefit that it'll be visible when the prop is spinning. And I figure if the ring is strong enough to maintain its circumference, the load on the prop should be marginal since it's spinning around its own center of mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the induced drag on the prop not large enough to warrant any thought, or would such a prop-winglet-ring (I'm sure there's a real name for it, anyone know what I'm talking about?) cause other disruptions of the airflow? Or perhaps there are other reasons, like it would simply be too hard to solve for constant-speed props?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="6919" LastEditDate="2015-04-14T09:38:45.967" LastActivityDate="2021-03-11T19:19:44.907" Title="Would connecting propeller blades with a continuous ring reduce induced drag?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="736" PostTypeId="1" AcceptedAnswerId="763" CreationDate="2014-01-08T10:56:08.927" Score="7" ViewCount="3647" Body="&lt;p&gt;In aeroelasticity, there are three main phenomena that one should take care of: &lt;a href=&quot;http://www.youtube.com/watch?v=I-tvVp1QT3U&quot;&gt;divergence&lt;/a&gt;, aileron reversal and &lt;a href=&quot;http://www.youtube.com/watch?v=jiN1dAdqQv4&quot;&gt;flutter&lt;/a&gt;. Each of them has an associated speed at which the phenomenon might start to occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During wind-tunnel tests it is possible to increase the flutter speed to have access to the divergence speed first by using some small masses smartly placed on the wing. This is due to the fact that usually flutter speed is smaller than divergence speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it always the case for aircraft (without additional masses on the wing)? If not do you have any example? If yes do you have an explanation why or a mathematical proof of it?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="62" LastEditDate="2014-01-08T14:00:10.073" LastActivityDate="2014-01-08T20:35:48.460" Title="Is flutter speed always smaller than divergence speed for aircraft?" Tags="&lt;aerodynamics&gt;&lt;aeroelasticity&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="737" PostTypeId="2" ParentId="735" CreationDate="2014-01-08T11:45:37.177" Score="19" Body="&lt;p&gt;What you're talking about does exist, &lt;a href=&quot;http://d32gw8q6pt8twd.cloudfront.net/wp-content/uploads/2012/01/Picture-19.png&quot;&gt;they are called Q-Tip Propellers.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that a propeller blade is just an airfoil - like a wing - and the basic aerodynamics are no different than a wing. But the rotation of the blade creates more phenomena than a wing, in particular the helicoidal vortex one sees behind the prop and causes all sorts of &lt;em&gt;propeller effects&lt;/em&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, nothing would prevent us from having winglets at the prop tips :&#xA;the advantages would be&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Making the prop more efficient by reducing the induced drag (same as a winglet on a wing )&lt;/li&gt;&#xA;&lt;li&gt;Reducing noise&lt;/li&gt;&#xA;&lt;li&gt;Keeping the propeller tip speed subsonic by decreasing its length&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The big problem is in aerodynamic stresses, and as far as I know there have been some quite spectacular failures during testing, so the solution is now to give a greater sweep to the tips (see that as equivalent to the 777 wing tip compared to the 787 for instance). Try and find articles on the &lt;em&gt;Hartzell Q-tip&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As naval propellers are wider and capable of deealing with bigger torque stresses, modern ones do have winglets. You could find some pictures on the web.  &lt;/p&gt;&#xA;" OwnerUserId="368" LastEditorUserId="64" LastEditDate="2014-01-08T17:32:22.917" LastActivityDate="2014-01-08T17:32:22.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="738" PostTypeId="1" AcceptedAnswerId="746" CreationDate="2014-01-08T14:22:33.703" Score="186" ViewCount="185244" Body="&lt;p&gt;Microsoft Flight Simulator has &quot;flight lessons&quot; with a virtual flight instructor, some of which teach concepts that are taught during actual flight training. These simulators are becoming &lt;em&gt;very&lt;/em&gt; realistic, and I can see them being helpful as an introduction to a subject prior to running the &lt;a href=&quot;https://aviation.stackexchange.com/q/7430/1696&quot;&gt;Hobbs meter&lt;/a&gt; and paying for actual flight time. Will this experience help or hurt someone who decides to become a real pilot? Is it a tool which can help students/instructors in an actual training environment? &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2019-11-22T16:47:20.473" LastActivityDate="2020-08-17T13:31:14.450" Title="Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?" Tags="&lt;flight-training&gt;&lt;flight-simulator&gt;" AnswerCount="14" CommentCount="3" FavoriteCount="68" ContentLicense="CC BY-SA 4.0" />
  <row Id="739" PostTypeId="2" ParentId="682" CreationDate="2014-01-08T14:24:36.407" Score="11" Body="&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To properly track GA aircraft, one needs to operate professional equipment or an ATC datastream, both which are not available to most websites.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Flight radar 24 shows GA traffic in some occasions, but in general it cannot track these aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FR24 works primarily on ADS-B, which is a surveillance technology that transmits aircraft information including position. Strictly speaking, ADS-B messages are not responses since they are unsolicited transmissions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;General aviation equipped with only a Mode A/C (/S) transponder will not transmit ADS-B data. Mode A/C radar replies do not contain position information encoded in them so even if the receiver receives these responses, the position cannot be determined from them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only if a message is received by 4 receivers which are carefully synchronized in time, it is possible to determine the position that the message was sent from by analyzing the times of arrival at each receiver. The travel distance of the signal to each receiver is different and even though the signal travels at the speed of light, the time difference of arrival is measurable. Using the 4 times of arrival the position can be revealed using a process called multilateration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FR24 is using this method for aircraft that transmit Mode S replies but for Mode A/C it is difficult. Firstly there is no aircraft identifier the A/C messages. If a lot of aircraft are flying with the same Mode A code (e.g. 1200 VFR) the arrival times quickly become ambiguous. To add to the difficulty there is no difference between the Mode A and Mode C message formats, so you might easily be comparing the time of a Mode A message from one receiver to a Mode C message from another.&#xA;Professional multilateration systems used for ATC make use of transmission antenna's that interrogate the aircraft transponders (like radar) to remove any ambiguities. This is not allowed for hobby systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally FR24 works on 1090 MHz ADS-B messages. In the USA, an additional ADS-B technology is in use on 978 MHz (UAT). So even if GA is ADS-B equipped, in the USA they might not be detected by FR24. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to properly track GA aircraft, one needs professional equipment or an ATC datastream, both which are not available to most websites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA provides 5 minute delayed radar track of aircraft, but only of those aircraft that fly on an IFR flight plan are included. Also aircraft owners can opt-out of that system for privacy reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some websites that show GA movement. One that I like is the monitoring website for residents living near &lt;a href=&quot;http://inzicht.bezoekbas.nl/&quot;&gt;Amsterdam airport Schiphol&lt;/a&gt;. The website is fed by ATC data, with a delay of about 1 minute. It shows all traffic except military. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-08T14:24:36.407" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="740" PostTypeId="1" AcceptedAnswerId="742" CreationDate="2014-01-08T14:54:53.527" Score="8" ViewCount="4158" Body="&lt;p&gt;Normal commercial jets drop gas masks when cabin pressure drops, and supply oxygen, but, where does that oxygen come from? Do commercial jets store oxygen? If they do, isn't pressurised oxygen very flammable and too hazardous to carry?&lt;/p&gt;&#xA;" OwnerUserId="327" LastActivityDate="2014-01-21T21:21:46.217" Title="Where does the Oxygen for the emergency gas masks come from?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;jet&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="741" PostTypeId="2" ParentId="740" CreationDate="2014-01-08T15:18:33.987" Score="5" Body="&lt;p&gt;Wikipedia has an excellent article on the subject:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Emergency_oxygen_system&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Emergency_oxygen_system&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases the oxygen masks are connected to a central oxygen supply (or more accurately, a  supply of breathing gas, containing a mix of oxygen and other gas). The oxygen can also be generated using a &lt;a href=&quot;http://en.wikipedia.org/wiki/Chemical_oxygen_generator&quot; rel=&quot;nofollow&quot;&gt;chemical device&lt;/a&gt;, one for each oxygen mask or seat row.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: contrary to what many people believe, oxygen is not required during normal flight. The outside air at high altitude still contains the same percentage of oxygen (21%) as on the ground. The outside air is pressurized and fed into the fuselage, allowing normal breathing.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-08T15:33:14.480" LastActivityDate="2014-01-08T15:33:14.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="742" PostTypeId="2" ParentId="740" CreationDate="2014-01-08T15:19:58.747" Score="12" Body="&lt;p&gt;On commercial aircraft the oxygen supply of the masks in the cabin comes either from a chemical oxygen generator or a centralized oxygen bottle system. The flight deck is always equipped with pressurized oxygen masks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chemical oxygen generators generate lots of heat when they are activated. When normally placed in their overhead compartments the heat is slowly dissipated. However, oxygens generators are hazardous when canisters are not in their appropriate place. The &lt;a href=&quot;http://www.ntsb.gov/doclib/reports/1997/aar9706.pdf&quot; rel=&quot;noreferrer&quot; title=&quot;NTSB accident report&quot;&gt;ValuJet Flight 592&lt;/a&gt; crash into the Everglades on 11 May 1996 was caused by a fire after improperly packed oxygen generators in the cargo hold were accidentally activated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressurized oxygen bottles also are hazardous. Not only because the oxygen can turn a small fire into a blaze but if the high pressure bottles explode they cause substantial damage. On &#xA;25 July 2008 an oxygen bottle installed in a &lt;a href=&quot;http://www.atsb.gov.au/media/2409291/ao2008053.pdf&quot; rel=&quot;noreferrer&quot; title=&quot;ATSB Qantas Flight 30 report&quot;&gt;Qantas Boeing 747&lt;/a&gt; ruptured and propelled itself upward through the floor into the cabin. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2014-01-08T20:23:34.293" LastActivityDate="2014-01-08T20:23:34.293" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="743" PostTypeId="2" ParentId="740" CreationDate="2014-01-08T15:23:38.220" Score="6" Body="&lt;p&gt;Airliners do not carry tanks of oxygen for the &quot;rubber jungle&quot; when the ox masks are deployed.  The oxygen is created by chemical reaction within canisters stored in the overhead that are not activated until the rubber jungle drops down.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This chemical reaction does create a lot of heat.  That's what caused the Valuejet fire and crash in the Florida everglades a few years ago.  The canisters were being shipped and were not clearly marked as hazardous cargo, and other safety steps were missed that may have inerted the canisters.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the many millions probably billions of canister-hours that these devices have been used over the years, I would conclude they are safe.  Given the disaster that happened when they were handled improperly for shipping, I would also say the airlines cannot lower their guard on shipping these apparently harmless canisters at any time, ever.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-21T21:21:46.217" LastActivityDate="2014-01-21T21:21:46.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="744" PostTypeId="2" ParentId="738" CreationDate="2014-01-08T15:27:19.093" Score="64" Body="&lt;p&gt;It can definitely help: when I did my instrument rating my instructor used MS FS to walk through (fly through?) various procedures before doing them for real. He also used it for NDB training because the aircraft we used didn't have ADF. I found it very useful, and if I had bought it myself it would probably have saved me a lot of time and money. The main benefit for me was that it lets you run through procedures to practice getting all the steps right and in the right order; I've never used any scenarios like the ones you mentioned so I don't know how useful they are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another very useful simulator I've used is the &lt;a href=&quot;http://www.mypilotstore.com/mypilotstore/sep/6210&quot; rel=&quot;noreferrer&quot;&gt;Garmin G1000 PC trainer&lt;/a&gt;. The G1000 has so many features that trying to identify them all while sitting in an actual aircraft is difficult, even if you have the aircraft available and can pay for it. It also lets you practice various failure modes, which is often difficult to do in the real aircraft. Garmin provides simulators for their 'basic' aviation GPS units too, and they're great for the same reason: you can play around as much as you like. There's no doubt in my mind that they help very significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that as glass cockpits become more and more common, simulation will become more and more important. They're great tools, but they also bring a lot of complexity and learning how to handle that complexity safely is a lot easier using a simulator. Of course you eventually need to go up, fly, and try out what you've learned for real, but it's no fun trying to flip through a G1000 user guide in flight.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="21864" LastEditDate="2018-08-02T21:01:55.620" LastActivityDate="2018-08-02T21:01:55.620" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="745" PostTypeId="2" ParentId="735" CreationDate="2014-01-08T16:17:38.067" Score="11" Body="&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Ducted_fan&quot;&gt;ducted fan&lt;/a&gt; comes close to what you're describing, although the ring around the propeller is stationary instead of attached to and spinning with the propeller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of a ducted fan is higher efficiency due to reduced propeller blade tip losses (essentially induced drag) but this efficiency advantage is lost at higher speeds and/or lower thrust demand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &quot;normal&quot; aircraft, the drawbacks of a ducted fan outweigh the efficiency gains. Ducted fans are mainly used in airships and VTOL aircraft like the infamous &lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_X-22&quot;&gt;Bell X-22&lt;/a&gt;. They are also used in most jet model airplanes.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-08T16:26:43.977" LastActivityDate="2014-01-08T16:26:43.977" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="746" PostTypeId="2" ParentId="738" CreationDate="2014-01-08T16:40:52.180" Score="163" Body="&lt;p&gt;&lt;strong&gt;Clarification&lt;/strong&gt;:&lt;br&gt;This was written about Microsoft Flight Simulator X (FSX).   Parts of the answer probably apply to the new Microsoft Flight Simulator (2020 release), but that isn't what I had in mind when writing this.  Maybe a new answer will be appropriate after using MSFS for some time.&lt;/p&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/744/7691&quot;&gt;@Pondlife gave a very good answer&lt;/a&gt;, and I'll add a few bits to that.&lt;/p&gt;&#xA;&lt;p&gt;Even after having gotten my license, I still use flight sims (mainly Microsoft FSX and X-Plane 10) for some practice.&lt;/p&gt;&#xA;&lt;p&gt;Before flying into an unfamiliar airport, or over an unfamiliar area, I'll often load it up in a simulator, and fly it.&lt;/p&gt;&#xA;&lt;p&gt;Especially when I was a student, I found this incredibly helpful for my long cross country flights. You can look at a map all you want, but its still not the same as sitting in the simulator, and looking around (&lt;em&gt;&amp;quot;I see the mountain on my left.... and the lake below me.  I can follow this valley all the way to the airport...&amp;quot;&lt;/em&gt; etc). And I've generally found the simulator, with good terrain and textures loaded, can be pretty close to reality.&lt;/p&gt;&#xA;&lt;p&gt;The night before I did a student flight from &lt;a href=&quot;http://skyvector.com/?ll=46.61734816682296,-123.93806388012696&amp;amp;chart=1&amp;amp;zoom=6&amp;amp;plan=A.K1.KBFI:G.47.43112208056429,-122.21923828336968:A.K1.KPLU:G.46.53801903196894,-122.4243164083625:G.45.966933325303984,-122.55703233623723:G.45.689467140542064,-122.72421092615514:A.K1.KVUO&quot; rel=&quot;noreferrer&quot;&gt;KBFI to KVUO&lt;/a&gt;, I flew the entire thing in FSX. The next day, it really felt pretty much like making the same flight all over again. Based on the landmarks, timing, views, etc, I knew exactly where I was, and I was confident that everything was going right.&lt;/p&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;That said, in my opinion there are some things simulators do very poorly.&lt;br&gt;&#xA;Some of these are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Takeoffs&lt;/strong&gt;&lt;br&gt;The application of power and left-turning tendency on the ground just doesn't feel realistic at all. The climb out doesn't feel right.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Landings&lt;/strong&gt;&lt;br&gt;Ground effect is difficult to observe in a simulator. The flare doesn't feel like reality, and touching down (or bouncing) is not realistic at all.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Cross Control, Slip, Spin &amp;amp; Unusual Attitudes&lt;/strong&gt;&lt;br&gt;Anything beyond basic maneuvers up to 30 degrees bank or 20 degrees climb doesn't match reality.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This is dependent on your simulator, some perform certain things more realistically than others.&lt;/p&gt;&#xA;&lt;p&gt;Because of these limitations, I would NOT use a flight simulator to try to learn takeoffs, landings, or certain maneuvers. (You can learn the &amp;quot;procedure&amp;quot; in a simulator... when to reduce power, when to add flaps. But the &amp;quot;feel&amp;quot; will be all wrong).&lt;/p&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;If you're going to try to incorporate flight sim into your training, there are some basic things you should do:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Spend LOTS of time configuring it&lt;/strong&gt;&lt;br&gt;Unlike a video-game, this is not &amp;quot;plug-n-play&amp;quot;. Spend time learning &lt;em&gt;all&lt;/em&gt; the controls.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Turn on Realism&lt;/strong&gt;&lt;br&gt;When adjusting your controls, set all &amp;quot;null-zones&amp;quot; to zero, set &amp;quot;Sensitivity&amp;quot; to maximum, turn off helpers like &amp;quot;auto-mixture&amp;quot; and &amp;quot;auto-rudder&amp;quot;, etc. (However, I do keep &amp;quot;Gyro-Drift&amp;quot; turned off in my sim.  Its annoying, and adds little practical value)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Turn on Weather&lt;/strong&gt;&lt;br&gt;The flight simulators typically come pre-setup with zero wind, good weather, standard temperature, etc. Configure yours to pull from real-world weather sources, or add some clouds, a variety of winds, and don't always fly at noon. Set the timing for early morning flights, twilight flights, night flights, etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;Another &amp;quot;fun&amp;quot; area where flight simulators can be slightly helpful is in emergency procedures.&lt;/p&gt;&#xA;&lt;p&gt;Typically in real-world training, my instructor told me:  &amp;quot;We're going to practice engine-out emergencies&amp;quot; and my mind immediately starts preparing for that... And naturally, we have to do them at a safe altitude in a safe area.&lt;/p&gt;&#xA;&lt;p&gt;In a flight simulator, you can set up the computer to give you a random emergency at a random time. You might get the problem on short-final, or over a metro-downtown area. Something that you just &lt;em&gt;can't&lt;/em&gt; do in reality.&lt;/p&gt;&#xA;&lt;p&gt;I haven't had any real-life emergencies, so I don't know how accurate a flight simulator is. But I believe that &lt;em&gt;some practice&lt;/em&gt; is better than no practice at all, and flight sim lets me fly into storms, icing, get lost in fog, fly approaches below minimums, have an engine seize up on me, etc, all without risking my butt or a $200,000 airframe.&lt;/p&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;&lt;em&gt;Since @Lnafziger suggested more specifically addressing flight training:&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;I do believe that flight sim can help with certain aspects of training, but in other areas, it is no help at all, or actually harmful.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Training Areas simulators can help with:&lt;/strong&gt;&lt;p&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Procedures&lt;/strong&gt;&lt;br&gt;Reviewing steps and procedures &lt;em&gt;before&lt;/em&gt; going in the air.  For example, for a student, steep turns or stall recovery can be a little nerve wracking at first. It may be much easier (and cheaper) to do it in a sim with an instructor, discussing all the steps and reasons for actions. Then when the student gets in the air, they won't have the &amp;quot;feel&amp;quot; for it, but at least the general process is already familiar.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Navigation&lt;/strong&gt;&lt;br&gt;Tuning and identifying VORs, and interpreting the needles can be done just as well be done on the ground as in the air. If the sim has good, realistic terrain (I prefer &lt;a href=&quot;http://www.megascenery.com/&quot; rel=&quot;noreferrer&quot;&gt;MegaSceneryEarth&lt;/a&gt;), it can also be used for some visual reference lessons.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Instrument interpretation&lt;/strong&gt;&lt;br&gt;Scanning and cross-checking the 6-pack of instruments can be done in a simulator just fine, and a student can practice doing it for long periods of time for a fraction of the cost of flight time.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;Training Areas simulators are very bad at:&lt;/strong&gt;&lt;p&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;On the ground &amp;amp; Outside the plane&lt;/strong&gt;&lt;br&gt;Anything on the ground, such as taxiing and parking, or anything outside the airplane, such as pre-flight inspection, or weather interpretation, just doesn't work in a sim.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Radios&lt;/strong&gt;&lt;br&gt;I haven't seen any flight sims that really work for the practice of talking on or listening to the radios. (I haven't used VATSIM, which &lt;em&gt;might&lt;/em&gt; help). I don't think there's any good substitute for actually flying in a real airspace while simultaneously engaging in real radio conversations.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Feel&lt;/strong&gt;&lt;br&gt;Even the best full-motion sim isn't a substitute for the forces a student feels in a real airplane. This is especially true on ground-reference maneuvers, takeoffs, and landings, where I feel sims fall far short of reality.  No one will ever get a &amp;quot;feel&amp;quot; for the plane from a simulator.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;For much more information on the topic, I recommend these books:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wiley.com/WileyCDA/WileyTitle/productCd-1118105028.html&quot; rel=&quot;noreferrer&quot;&gt;Scenario-Based Training with X-Plane and Microsoft Flight Simulator&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/0bOfqm.jpg&quot; alt=&quot;Scenario-Based Training&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/com/0764588222&quot; rel=&quot;noreferrer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Microsoft Flight Simulator X For Pilots Real World Training&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6mud3m.jpg&quot; alt=&quot;Real World Training&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;And here's a picture of my old simulator rig.&lt;br&gt;&#xA;(Its been improved a bit since this picture)&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/91TBhm.jpg&quot; alt=&quot;My old sim setup.&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2020-08-17T13:31:14.450" LastActivityDate="2020-08-17T13:31:14.450" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="747" PostTypeId="2" ParentId="389" CreationDate="2014-01-08T17:15:16.690" Score="2" Body="&lt;p&gt;You all give some nice explanation but to answer the actual question, no, there are operations, where no alternate is required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some really remote airports which are right in the middle of nowhere are referred as isolated airports. If you are going to these fields, no alternate will be required but you are required to take a lot of extra fuel (EASA requires the fuel you would consume while holding for 2 hours in 1500 feet above the destination). I chose this example because I know that this is pretty much the same all around the world, but different authorities also approve some other flights without having an alternate. See the FAA, or even the very strict EASA which doesn't require an alternate if independent runways with instrument approaches and sufficient weather information for the destination, forecasting 'good' weather are available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does not depend on the state you are going to, anyway this state has to except your operation first, but on the state of the operator. The exact procedures saying for which kind of operation you need which amount of alternates, where they must be located, what minimum equipment they need to offer and how much fuel you need to take is written in the operations manual, which is at least as restrictive as the rules of the state of the operator.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="938" LastEditDate="2014-09-11T21:24:26.517" LastActivityDate="2014-09-11T21:24:26.517" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="748" PostTypeId="2" ParentId="738" CreationDate="2014-01-08T17:31:25.607" Score="20" Body="&lt;p&gt;Sorry, I know that's not nice to read but all in all I like to answer your question with a no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight simulators on your computer doesn't offer the possibility to learn how to actually fly an airplane, they even teach you to act in a different way and in my eyes this might be even very dangerous especially if you only have a little flying experience yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there are exceptions: I now don't like to talk about flying but operating an airplane. A flight simulator for sure offers a good possibility to train procedures. To learn instrument approaches you maybe better go into a FNPT but other procedures and flows like organising approaches, work on a proper timing and workflow, practice briefings and even get used to some instruments. Tracking VORs and NDBs outbound from different positions, deciding for the right holding entry and all this stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But once again, a PC flight simulator does not teach you flying the actual airplane and can even be a disadvantage for your initial flight training. If you get used to flying and handle your aircraft well, then it probably is a great way to learn more complex operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another problem I've often observed is that people who 'trained' a lot on their computer become far too confident on what they are doing and very used to procedures which in the actual plane may not work. Always remember that you are a pilot who likes to learn and use the computer only as a helpful device to get a impression how things basically work. If then questions occur, ask your flight instructor. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="8375" LastEditDate="2015-08-21T13:17:27.627" LastActivityDate="2015-08-21T13:17:27.627" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="749" PostTypeId="2" ParentId="735" CreationDate="2014-01-08T18:04:39.690" Score="2" Body="&lt;p&gt;For historical perspective do some research on the Culver Channel Wing produced in 1952-53.  This twin engine (pusher) plane has two ducts that do not completely encircle the prop but are part of the wing.  This lead to extremely short take off capabilities because the airflow over the wing was not tied to forward ground speed. I would even go as far to say that it was an early step in ducted fan VTOL capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This article by &lt;A HREF=&quot;http://www.airport-data.com/articles/view/N5855V-1964-Custer-Channel-Wing-CCW-5-Rev-4:1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Doug Robertson&lt;/A&gt; posted in 2005 on &lt;A HREF=&quot;http://www.airport-data.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;airport-data.com&lt;/A&gt; contains some beautiful pictures, and an what appears to be a well researched narrative history of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="19195" LastEditDate="2017-01-15T09:45:07.980" LastActivityDate="2017-01-15T09:45:07.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="750" PostTypeId="2" ParentId="735" CreationDate="2014-01-08T18:35:01.067" Score="5" Body="&lt;p&gt;Q-Tips and Ducted fans are the big ones to solve the problems you're thinking of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your ring idea would be very difficult to implement for a number of reasons, weight being primary. A metal ring all the way around the propeller would add a significant amount of weight to the aircraft, which would likely cancel out any efficiency gains you get from stabilizing the airflow. In addition, the tips of a propeller are already experiencing several  &lt;em&gt;thousand&lt;/em&gt; G's at normal operating RPMs. This is acceptable because the prop gets continuously lighter as you approach the tips. But if you were to attach a ring of metal weighing a few dozen pounds, the forces would be astronomical, and your prop would very quickly fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second issue is that in order to have efficient propellers, we rotate the blades slightly to change the angle at which they bite into the air. These are called constant speed propellers, and they're already somewhat complicated. If you go and add a second pivoting point to the prop tips so that they can move inside the ring, you're just adding a bunch of bearings, grease, weight, and another failure point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, balancing the ring would likely be a difficult task. First your ring would have to be manufactured to very precise tolerances which would be quite expensive. The slightest nick or dent in the ring (which happens frequently to propellers) will cause it to become unbalanced and would at minimum require work, and at most could cause the whole propeller to shake itself apart. This is already a minor concern for props, but when you put your heavy disk out on a long arm from it's fulcrum, then subject it to incredibly high G forces, you're just amplifying any faults it may have.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-08T18:35:01.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="751" PostTypeId="1" AcceptedAnswerId="752" CreationDate="2014-01-08T18:42:43.303" Score="52" ViewCount="43180" Body="&lt;p&gt;I did my training around the Seattle area, and was told that landing at SeaTac Airport (the region's major International/Commercial airport), while not strictly forbidden, was definitely frowned upon because it can slow down and interfere with the big planes on schedules. To discourage GA aircraft from using the big airport, they have a variety of landing fees, ramp fees, and prior-approval requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But later, I moved near MCI, and was told that landing at the big airport was no big deal.  That they're actually happy to have little planes there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly small GA planes, do you land at the major airports in your area?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What advanced preparations can you make to minimize your impact on the &quot;big boys&quot;, and remain a good airspace citizen?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="69" LastEditDate="2014-01-09T02:26:34.520" LastActivityDate="2015-07-23T00:31:48.757" Title="Can you fly a light GA airplane into a major hub? What operational considerations are there if you do?" Tags="&lt;usa&gt;&lt;airport&gt;&lt;general-aviation&gt;" AnswerCount="10" CommentCount="2" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="752" PostTypeId="2" ParentId="751" CreationDate="2014-01-08T18:50:19.327" Score="61" Body="&lt;p&gt;Can you?  Absolutely, and air traffic control will treat you (almost) like any other airplane.  You are supposedly handled on a first-come-first-serve basis (reality is slightly different with different aircraft speeds, etc.).  Do the airlines like it if you slow them down?  No, but it's part of the system and the way that it works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very often, there are multiple runways at bigger airports, and sometimes there are even shorter runways that are dedicated for airplanes that don't need to land on the same one as the &quot;big boys&quot;.  Even if not, they will work you in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, that being said, &lt;em&gt;very often&lt;/em&gt; there is a better option.  As you said, there are usually high fees at the big airports, so landing at a smaller satellite airport can often save you money &lt;strong&gt;and&lt;/strong&gt; save you time because you won't have to taxi as far or sit and wait in line to get out.  An extra 15 minutes by car can be better than an extra 30 minutes while taxiing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as being prepared, it isn't really much different than smaller airports &lt;em&gt;other&lt;/em&gt; than the fact that ATC is &lt;em&gt;much&lt;/em&gt; busier.  They don't have the time/tolerance to keep repeating instructions to you, and expect you to be &quot;on your game&quot;.  When they rattle off taxi instructions like &quot;Cessna N1234, taxi to the ramp via Alpha, Tango, Echo, and Xray. Hold short of runway 23.&quot; they expect a quick readback and for you to follow instructions exactly because they need to move on to the next guy.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will also help everyone out if you don't fly your final approach the way that most people are taught for an entire 10 mile final:  very close to your actual landing speed.  In fact, you are usually landing on a runway that is 4X+ the distance that you need and you can slow down fairly quickly (especially compared to a jet), so if you can fly an extra 20 (or 80) knots as long as possible, it will be greatly appreciated and keep traffic moving.  Make sure that you leave yourself enough time to slow down at the end and above all else, &lt;strong&gt;&lt;em&gt;be safe&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-08T19:22:02.640" LastActivityDate="2014-01-08T19:22:02.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="753" PostTypeId="1" AcceptedAnswerId="772" CreationDate="2014-01-08T19:02:42.673" Score="22" ViewCount="6525" Body="&lt;p&gt;During initial flight training a lot of emphasis is placed on stalls and spins and how to recover from them, but is it possible to recover from a fully developed spin in an airliner? Do these large aircraft have enough rudder authority to pull it off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has it ever been done? And is it part of the training for specific type ratings? (in a simulator of course)&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="64" LastEditDate="2016-02-02T03:29:07.503" LastActivityDate="2017-09-26T23:30:14.827" Title="Is spin recovery possible in an airliner?" Tags="&lt;airliner&gt;&lt;spins&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="754" PostTypeId="2" ParentId="751" CreationDate="2014-01-08T19:27:27.963" Score="29" Body="&lt;p&gt;Just to add to Lnafziger's answer (which is entirely correct), the FAA has designated five airports as &quot;High Density Traffic Airports&quot; (covered in &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol2/pdf/CFR-2011-title14-vol2-part93-subpartK.pdf&quot;&gt;FAR Part 93 Subpart K&lt;/a&gt;) which specifically limit the number of &lt;em&gt;scheduled&lt;/em&gt; IFR arrivals, and it's easy to misread that as &quot;you can't land here.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 93.129 specifically says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) IFR. The operator of an aircraft&#xA;  may take off or land the aircraft under&#xA;  IFR at a designated high density traffic&#xA;  airport without regard to the maximum&#xA;  number of operations allocated&#xA;  for that airport if the operation is not&#xA;  a scheduled operation to or from a high&#xA;  density airport and he obtains a departure&#xA;  or arrival reservation, as appropriate,&#xA;  from ATC. The reservation is&#xA;  granted by ATC &lt;strong&gt;whenever the aircraft&#xA;  may be accommodated without significant&#xA;  additional delay&lt;/strong&gt; to the operations&#xA;  allocated for the airport for which the&#xA;  reservations is requested.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An almost identical exemption for VFR is listed in paragraph (b).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So they're essentially giving you a heads up that ATC can simply turn you away, and will likely do so during peak operation periods. However, during off hours (including hours when High Density rules are not in effect), there is no reason you can't land at even the biggest of [civilian] airports in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High Density Airports currently include Laguardia (KLGA), John F. Kennedy (KJFK), Newark (KEWR), Reagan National (KDCA), and O'Hare (KORD).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Exceptions...&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LGA and DCA require a slot reservation during most hours for unscheduled operations through the &lt;a href=&quot;https://www.fly.faa.gov/ecvrs/index.html&quot;&gt;e-CVRS&lt;/a&gt; system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, DCA has very strict requirements which allow for only 48 GA flights each day. Among the requirements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.tsa.gov/about-tsa/armed-security-officer-aso-program&quot;&gt;TSA Approved Armed guard&lt;/a&gt; on board.&lt;/li&gt;&#xA;&lt;li&gt;No changes to the passenger manifest 24 hours prior to the flight.&lt;/li&gt;&#xA;&lt;li&gt;TSA inspection of aircraft and passengers at a &lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/dassp_gatewaylist_3-21-2013.pdf&quot;&gt;gateway airport&lt;/a&gt; prior to arrival.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See the whole list on the &lt;a href=&quot;http://www.tsa.gov/stakeholders/security-programs-and-initiatives&quot;&gt;TSA's website&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And don't forget, the Washington, DC area has &lt;a href=&quot;http://en.wikipedia.org/wiki/Washington,_DC_Metropolitan_Area_Special_Flight_Rules_Area&quot;&gt;special flight rules&lt;/a&gt; in general. In other words, don't ever expect to land at DCA unless you have a really good reason.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="923" LastEditDate="2014-04-09T03:20:19.623" LastActivityDate="2014-04-09T03:20:19.623" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="755" PostTypeId="2" ParentId="738" CreationDate="2014-01-08T19:37:47.050" Score="7" Body="&lt;p&gt;Though in the presence of other great answers, my two cents are just worth two cents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read at several places that &lt;em&gt;&lt;a href=&quot;https://www.wikihow.com/Chair-Fly&quot; rel=&quot;nofollow noreferrer&quot;&gt;chair flying&lt;/a&gt;&lt;/em&gt; at home is very beneficial during flight training. However it appears to be very boring. A better alternative is always a flight simulator. As everyone has mentioned, it is not a replacement to actual flying, but at least it makes you prepare for the steps to do in a certain situation.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2018-03-14T17:16:36.473" LastActivityDate="2018-03-14T17:16:36.473" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="756" PostTypeId="1" AcceptedAnswerId="757" CreationDate="2014-01-08T19:44:20.540" Score="11" ViewCount="2866" Body="&lt;p&gt;I really appreciate &lt;a href=&quot;http://skyvector.com&quot;&gt;skyvector.com&lt;/a&gt; as a tool for initial route planning and providing me with a good lookout to the upcoming VFR flight, but honestly I'm not very satisfied with the FAA Sectional charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using these charts navigation in some more congested areas is tough work especially as I'm not very familiar with the area yet. Its often useful to have a satellite picture of these areas to identify some helpfull landmarks, which might not be shown on the sectional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know how to transfer the skyvector route to Google Maps, or know an alternative to achieve a similar result?&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="69" LastEditDate="2014-01-18T17:07:12.973" LastActivityDate="2014-05-15T19:26:16.413" Title="Can I display the route which I have created with skyvector.com on google maps?" Tags="&lt;usa&gt;&lt;flight-planning&gt;&lt;navigation&gt;&lt;visual-flight-rules&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="757" PostTypeId="2" ParentId="756" CreationDate="2014-01-08T19:54:42.623" Score="2" Body="&lt;p&gt;It's not web based, but you can use Google Earth for this — &lt;a href=&quot;http://www.gelib.com/aeronautical-charts-united-states.htm&quot; rel=&quot;nofollow&quot;&gt;There are overlays for aeronautical charts available&lt;/a&gt;, and you can do all your flight planning by entering routes in Google Earth. Then just turn off the sectional and you'll have the Google Earth satellite imagery to work with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an added bonus (relating to your comment about mainly using an Android tabled): Google Earth &lt;a href=&quot;https://play.google.com/store/apps/details?id=com.google.earth&quot; rel=&quot;nofollow&quot;&gt;is available as an Android application&lt;/a&gt; (and the plugin version of the chart overlay should work in the tablet app — I know it works in the &lt;a href=&quot;https://itunes.apple.com/us/app/google-earth/id293622097?mt=8&quot; rel=&quot;nofollow&quot;&gt;iOS version of Earth&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;BIG SCARY IMPORTANT DISCLAIMER&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;As the folks who publish that collection of charts will tell you, the charts are not always current and thus &lt;strong&gt;&lt;em&gt;should not be used for navigational purposes&lt;/em&gt;&lt;/strong&gt; (much like SkyVector).  You can of course replace the chart graphics with current ones (or locate a chart collection that &lt;em&gt;is&lt;/em&gt; current) if you want to, but as you're only using this as a pre-flight planning aid and will be doing your &lt;em&gt;real&lt;/em&gt; flight planning with current charts and data the ones provided in the Google Earth Library are probably &quot;good enough&quot; for your purposes.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2014-05-15T19:26:16.413" LastActivityDate="2014-05-15T19:26:16.413" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="758" PostTypeId="1" AcceptedAnswerId="761" CreationDate="2014-01-08T19:59:25.997" Score="38" ViewCount="87662" Body="&lt;p&gt;What, if any, requirements are there to maintain a private pilot certificate? For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do I have to renew my certificate after a period of time? E.g. annually, 5 years, 10 years&lt;/li&gt;&#xA;&lt;li&gt;Do I have to receive a minimum number of continued training hours?&lt;/li&gt;&#xA;&lt;li&gt;Do I have to fly a minimum number of hours?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For instance, say I had enough money/time to go out and start the process of getting a private pilot certificate tomorrow, but I didn't plan to make use of it in the foreseeable future, would it cost me more in time and money than if I waited until I had plans to use it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is assuming I live and fly in the USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related Question:&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/627/how-much-generally-speaking-does-it-cost-to-learn-how-to-fly&quot;&gt;How much, generally speaking, does it cost to learn how to fly?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&#xA;Note I understand the safety aspect of not practicing and &quot;getting rusty&quot;, for lack of a better term on my part, and that practically a certain amount of retraining would be required (though it seems that it is not legally required). The retraining is not mandated and I would need to retrain until I felt proficient enough technically and practically. Retraining would include familiarizing myself with the controls, instruments, radio, physics, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My main concern was that (a) at some point I my certificate would expire and I would have to go through the process again, making the initial effort practically useless, (b) that I may have to pay a significant amount of money to keep the certificate from expiring, or (c) that I would have to commit to a certain number of hours (instructed or solo) per year to keep the certificate.&lt;/p&gt;&#xA;" OwnerUserId="378" LastEditorUserId="3386" LastEditDate="2017-05-09T13:22:34.963" LastActivityDate="2017-05-09T13:22:34.963" Title="What does it take to maintain a private pilot certificate?" Tags="&lt;usa&gt;&lt;cost&gt;&lt;ppl&gt;&lt;far-61&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="760" PostTypeId="2" ParentId="758" CreationDate="2014-01-08T20:09:38.203" Score="12" Body="&lt;p&gt;The plain and simple answer to your updated question is that once you get your pilot license, it is good forever.  You can go 50 years without flying, and the license itself is still valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it comes time to fly again, depending on the type of airplane that you want to fly, you will probably also need a medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will need to have a Flight Review within the previous two years that you will need to be able to pass (and you have to be &lt;em&gt;proficient&lt;/em&gt; in order to pass it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most importantly, in order to be &lt;strong&gt;&lt;em&gt;safe&lt;/em&gt;&lt;/strong&gt;, you will want to fly enough to be proficient and comfortable in the airplane so that you don't hurt yourself, others, or the airplane.  If you go a long time without flying, it can be almost like starting over.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, the additional training that you will have to do in order to become comfortable  will end up costing you more in the long run, but you don't have to do anything to maintain just the license portion that you are asking about.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-08T21:37:19.680" LastActivityDate="2014-01-08T21:37:19.680" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="761" PostTypeId="2" ParentId="758" CreationDate="2014-01-08T20:11:53.653" Score="41" Body="&lt;p&gt;A license, once granted, is good forever (barring some enforcement action).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, you need more than just a license to fly.  To &lt;em&gt;use&lt;/em&gt; your license, while flying solo, you also need a Medical Certificate (if required for the aircraft or flight rules) and a Current BFR (Biennial Flight Review).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Medical Certificates are good for 5 years until you're 40, then good for 2 years.&#xA;Its a quick trip to an FAA approved doctor to examine you for any obvious medical conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A BFR is a review with an instructor every two years to make sure you're still proficient and safe.  If all goes well, it takes about 90 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;However&lt;/em&gt;&lt;/strong&gt;, if you want to fly passengers, you also need 3 landings within the previous 90 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to fly passengers &lt;em&gt;at night&lt;/em&gt;, you need 3 landings to a full stop, at night, within the previous 90 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your 90-day landings have lapsed, you can quickly fix it with 3 trips around the pattern, taking off and landing each time (touch-n-go during the day, or full-stop at night).  Then taxi back to the ramp, pick up your passengers, and go on your way.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="69" LastEditDate="2015-11-17T00:07:28.070" LastActivityDate="2015-11-17T00:07:28.070" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="762" PostTypeId="2" ParentId="758" CreationDate="2014-01-08T20:14:33.897" Score="5" Body="&lt;p&gt;There is no simple answer to this question because it depends how much you fly and how much time you need to re-learn after not flying for a while.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A US private pilot's license never expires, but you do lose currency. The recurring training requirement is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.1.1.35&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.56&lt;/a&gt;: you must pass a biennial flight review (BFR) every two years, which consists of one hour ground school and one hour in the air with an instructor. If you do not have a current BFR (or have passed an equivalent test) then you can't fly as PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from the BFR there is no requirement at all to fly regularly, nor is there a requirement to fly a minimum number of hours. That's for solo day VFR only; there are minimums if you intend to carry passengers, fly at night or operate under IFR (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#14:2.0.1.1.2.1.1.36&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.57&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in an extreme case, you could get your license and not fly for 20 years. Then you would 'just' need to pass a BFR to become legal again, with no need to do the theory and practical tests over again (a BFR is not a test). But you would need a valid third-class medical as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The costs are impossible to estimate because it depends on how long your break from flying is and how quick you are to pick it up again. If you don't fly for a year you might need a couple of hours with an instructor to be safe again, but if you don't fly for 5 years it's probably going to be much more time. This is definitely one case where 'safe' is a lot more important than 'legal'.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-08T20:29:03.047" LastActivityDate="2014-01-08T20:29:03.047" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="763" PostTypeId="2" ParentId="736" CreationDate="2014-01-08T20:35:48.460" Score="6" Body="&lt;p&gt;Flutter speed will usually be smaller than divergence speed. Flutter will appear first because as a phenomenon, by definition, describes the state of the deformation of the wing where it deflects for example up and down in a vibrating fashion. Divergence on the other hand is when the moments from the aerodynamic forces acting on the wing are larger than the restoring moments due to structural stiffness thus resulting in failure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of simplicity -since the entire calculation is pretty lengthy- let's imagine an airfoil at an angle of incidence &lt;code&gt;θο&lt;/code&gt; that's been twisted by an angle &lt;code&gt;θ&lt;/code&gt; due to aerodynamic loading. This additional angle θ is used to measure the twisting strain (dynamic) energy &lt;code&gt;0.5*K*θ^2&lt;/code&gt; where K is the stiffness of the airfoil - much like a spring's K constant. An increase in speed will increase angle θ and the corresponding strain energy stored in the structure. When the speed reaches the divergence speed the restoring forces are smaller than the aerodynamic forces and the angle θ becomes infinite but since infinite is impossible in reality, the structure fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very early airplanes (Wright, Langley) had major divergence problems and where unable to fly although they had airfoils capable of generating the lift necessary. The same airplanes with stiffer wings in later designs where able to fly. Modern airplanes due to proper design and stiffer materials have divergence speeds higher than flutter speeds. Divergence is a measure of the overall stiffness of the structure and is also used in order for the aircraft to get certified.&lt;/p&gt;&#xA;" OwnerUserId="376" LastActivityDate="2014-01-08T20:35:48.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="764" PostTypeId="1" AcceptedAnswerId="793" CreationDate="2014-01-08T21:24:35.790" Score="13" ViewCount="4120" Body="&lt;p&gt;In 2010 Fox News posted &lt;a href=&quot;http://www.foxnews.com/scitech/2010/03/13/future-jetpacks-sale-late-year/&quot;&gt;an article&lt;/a&gt; in which they quoted a representative of the FAA saying that the FAA might not regulate jetpacks (the representative did say that they could fall under Part 103). Do any regulations exist in the US for jetpacks?&lt;/p&gt;&#xA;" OwnerUserId="44" LastEditorUserId="247" LastEditDate="2014-12-11T18:33:38.693" LastActivityDate="2014-12-11T18:33:38.693" Title="What regulations in the US exist for jetpacks?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="765" PostTypeId="1" AcceptedAnswerId="1127" CreationDate="2014-01-08T21:48:41.560" Score="11" ViewCount="5512" Body="&lt;p&gt;When it comes to operating an aircraft, what are the practical differences between a &lt;em&gt;turbocharged&lt;/em&gt; engine and a &lt;em&gt;supercharged&lt;/em&gt; engine? I'm aware of the &lt;strong&gt;mechanics&lt;/strong&gt; - turbochargers being exhaust-driven, while superchargers are mechanically driven - so I'm looking for the &lt;strong&gt;differences in how pilots need to treat the systems&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do power settings need to be set differently?&lt;/li&gt;&#xA;&lt;li&gt;Are temperatures more of a concern with superchargers?&lt;/li&gt;&#xA;&lt;li&gt;Is it easier or harder to overboost a supercharger? If you do, are there waste gates?&lt;/li&gt;&#xA;&lt;li&gt;Do engines with superchargers need a cool-down period before being shut off?&lt;/li&gt;&#xA;&lt;li&gt;Any other operational differences that would be meaningful for pilots to know.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Similarly, what are the ownership implications of any differences? Does one cost more to maintain than the other due to the way they are constructed? Will a supercharged engine have a lower TBO because of the mechanical aspects of the system, or will it be the same as a turbocharged engine?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-09T05:48:52.503" LastActivityDate="2016-12-12T19:03:35.027" Title="To a pilot, does turbocharging differ from supercharging?" Tags="&lt;piston-engine&gt;&lt;turbocharged&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="766" PostTypeId="1" AcceptedAnswerId="770" CreationDate="2014-01-08T21:51:02.337" Score="12" ViewCount="2115" Body="&lt;p&gt;If I want to take an airplane to Europe, what additional aircraft equipment is required beyond the US requirements?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, I know that we need 8.33Khz spacing radios, what else is there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I heard that it will be changing in 2015 to have additional requirements.  What will those be, and will there be any exceptions (ie, can we obtain a waiver)?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T17:12:41.217" LastActivityDate="2015-05-09T11:58:14.720" Title="What additional aircraft equipment is required to fly a US registered airplane in Europe?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="767" PostTypeId="1" AcceptedAnswerId="768" CreationDate="2014-01-08T21:53:27.753" Score="17" ViewCount="20893" Body="&lt;p&gt;I got my private pilot license when I was 17 but was unable to continue flying. I am moving into a position to get back in the air, but I no longer have my log book as it was lost between moves. What is the best way to move forward? &lt;/p&gt;&#xA;" OwnerUserId="384" LastEditorUserId="39" LastEditDate="2014-01-09T18:41:32.940" LastActivityDate="2018-03-20T01:25:26.850" Title="How does a pilot replace their logbook if it has been lost?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="768" PostTypeId="2" ParentId="767" CreationDate="2014-01-08T21:58:11.700" Score="19" Body="&lt;p&gt;The best approach is to start a new logbook with totals that carry over from your latest FAA 8710 - in this case, it sounds like you will roll back to the hours from when you earned your private pilot certificate. There are &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.5,Ch1,Sec8&quot;&gt;some other options listed in FAA Order 8900.1, 5-172&lt;/a&gt;, but it's unlikely any of them will work for your situation (except, perhaps for &quot;Receipts for aircraft rentals&quot;, if your FBO is still open and still has the records).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can request a copy of your 8710 from the FAA, which I'm gonna quote here because that's the best way to not screw anything up:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airmen who have lost their logbooks or flight records may request copies of their files from the FAA [by sending &lt;strong&gt;&lt;em&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/media/COMPRQST.pdf&quot;&gt;this form&lt;/a&gt;&lt;/em&gt;&lt;/strong&gt;] to the following:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;FAA Airmen Certification Branch, AFS-760&lt;br/&gt;&#xA;    P.O. Box 25082&lt;br/&gt;&#xA;    Oklahoma City, OK 73125&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;or&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;FAA Aeromedical Certification&lt;br/&gt;&#xA;    P.O. Box 25082&lt;br/&gt;&#xA;    Oklahoma City, OK 73125&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Once you receive the copy, the first line in your new logbook should probably summarize all the totals from the 8710 (just like if it was a flight). The remarks would specify &quot;time forward from 8710 dated DD/MM/YYY&quot; or something to that effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best of luck getting your records back!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-08-01T20:20:29.090" LastActivityDate="2014-08-01T20:20:29.090" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="769" PostTypeId="2" ParentId="767" CreationDate="2014-01-08T22:23:16.840" Score="2" Body="&lt;p&gt;As you wrote: &lt;em&gt;&quot;I just want to restart recreational flying and possibly pursue additional ratings&quot;&lt;/em&gt;, you don't technically need your old log book to start flying again if you still have your license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the answers on &lt;a href=&quot;https://aviation.stackexchange.com/questions/758/what-does-it-take-to-maintain-a-private-pilot-certificate&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll need your license, a current medical, and a BFR.&lt;br&gt;But I don't think you need proof of hours.&lt;br&gt;   Of course, getting a fully signed off BFR is a lot easier if you have a log book showing recent time, but it is not required.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-01-08T22:23:16.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="770" PostTypeId="2" ParentId="766" CreationDate="2014-01-08T23:31:32.277" Score="7" Body="&lt;p&gt;An overview of ATC related avionics can be found on the &lt;a href=&quot;http://www.eurocontrol.int/articles/requirements-civil-aircraft&quot; rel=&quot;nofollow&quot; title=&quot;Eurocontrol avionics table&quot;&gt;Eurocontrol website&lt;/a&gt;. There are a couple of things changing in 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The list below includes change to ATC related avionics requirements in 2015. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition other avionic requirements not related to ATC are imposed, but that is outside my field of expertise. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;Surveillance&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2011:305:0035:0052:EN:PDF&quot; rel=&quot;nofollow&quot; title=&quot;Surveillance Performance &amp;amp; Interoperability&quot;&gt;Commission Implementing Rule (IR) (EU) No 1207/2011&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014R1028&amp;amp;from=EN&quot; rel=&quot;nofollow&quot;&gt;Commission Implementing Rule (IR) (EU) No 1028/2014 (Amendment of 1207/2011)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ADS-B&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B (1090ES) will be mandated  from 7 January 2017 for aircraft with MTOM &gt; 5700 kg and Max cruise TAS &gt; 250 Kts with an individual  certificate  of  airworthiness  first  issued on or after 8 June 2016. For aircraft certified before 8 June 2016 with the same MTOM and max cruise speed class ADS-B will be mandated after 7 June 2020 . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applies to all IFR flights in the European Civil Aviation Conference (ECAC) airspace, excluding oversea territories. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mode-S Elementary Surveillance (ELS)&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode S ELS will be mandated for all aircraft operating according to Instrument Flight Rules from 8 January 2015&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applies to all IFR flights in the ECAC airspace, excluding oversea territories. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mode-S Enhanced Surveillance (EHS)&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode S EHS will be mandated for &lt;strong&gt;new&lt;/strong&gt; aircraft with MTOM &gt; 5700 kg and Max cruise TAS &gt; 250 Kts from 8 January 2015. For existing aircraft in the same MTOM and max cruise speed class Mode S EHS will be mandated after 7 December 2017.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applies to all IFR flights in the ECAC airspace, excluding oversea territories. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Communication&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2009:013:0003:0019:EN:PDF&quot; rel=&quot;nofollow&quot;&gt;Commission Implementing Rule (IR)(EU) No 29/2009&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Controller-Pilot Data Link Communications (CPDLC)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CPDLC (VDL Mode 2) is mandated above FL285 from 5 February 2015&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applies to all IFR flights in the ECAC airspace, excluding oversea territories.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Safety Enhancements&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2011:336:0020:0022:EN:PDF&quot; rel=&quot;nofollow&quot;&gt;Commission Implementing Rule (IR) (EU) No 1332/2011&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From 1 December 2015 TCAS II version 7.1  will be mandated for all aircraft build before March 2012 with MTOM &gt; 5700 kg and Max cruise TAS &gt; 250 Kts operating in EU airspace. Aircraft first certified after 1 March 2012 already need to operate with TCAS II version 7.1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside EU airspace, but within ECAC airspace, TCAS version 7.0 is still allowed.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-09T11:58:14.720" LastActivityDate="2015-05-09T11:58:14.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="771" PostTypeId="2" ParentId="751" CreationDate="2014-01-08T23:43:34.193" Score="12" Body="&lt;p&gt;Must be an American thing to allow GA to land at major airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elsewhere in the world it's pretty much banned.   For example if you read the AIP sheet for Heathrow it says &lt;strong&gt;&lt;em&gt;&quot;Flights for recreational, commemorative, charity and record breaking purposes, light twin engined private aircraft and all light single engined aircraft will not be permitted to use the airport.&quot;&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elsewhere in the world, airports also tend to be located in class A airspace, which are IFR only and not open to VFR traffic.  So most PPLs without an IR rating would not be able to get anywhere near the airport anyway.&lt;/p&gt;&#xA;" OwnerUserId="389" LastActivityDate="2014-01-08T23:43:34.193" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="772" PostTypeId="2" ParentId="753" CreationDate="2014-01-08T23:44:07.257" Score="15" Body="&lt;p&gt;There were a lot of other mitigating factors in the Colgan Air 3407 crash. Was that one recoverable? It depends. It never should have got to the point of a stall in the first place. It was more preventable than recoverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in answer to your question, again, it depends. Every aircraft in the air can stall and be recovered, if responded to properly. But the plane may very well bend and break if the stall develops too far. Then it may not be recoverable. And most large airliners (or aircraft bigger than a few thousand pounds with multiple engines) aren't designed for the stresses of spins, so they never teach to a full stall. In those types of aircraft a full stall is much more dangerous, and they can be much more difficult to recover from, especially if you break something. Besides, in aircraft like that, you should receive plenty of direct warning long before you reach the point of a stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I was teaching, stalls and spins were one of my favorite subjects for early pilots. Especially in light trainers like the Cessna 150/152s. Those aircraft were always incredibly good at stalls/spins and incredibly forgiving. You can put a Cessna into a hands-off full stall if you trim it right, and it will stop rotating in a spin if you simply let go of it (and have enough altitude). I always taught my students spin recovery from a full spin, even at the Private Pilot level. And usually shortly after teaching them full stalls. I would stall it, make it rotate at least 3 or 4 times, and have them recover the spin. Then have them do it themselves. I never had to worry about my students not knowing how to recover from an unintentional stall/spin. By the time my students were learning to fly multis, I was teaching them more stall recognition and avoidance than recovery. Recovery is essentially the same in all aircraft. You just have to be sure to not reach that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's only one thing you really need with any aircraft in a stall/spin, and that's altitude. Unfortunately, takeoffs and landings are the most likely places for you to get behind the aircraft and let it unintentionally stall/spin. That's why you learn how to recognize them very early in your pilot training. You can't spin without a stall first, and just about any airplane will give you fair warning before you stall it. The trick is recognizing the situation before it becomes serious.&lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2014-01-08T23:44:07.257" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="773" PostTypeId="5" CreationDate="2014-01-09T00:49:36.273" Score="0" Body="&lt;p&gt;Weight-and-balance typically refers to insuring that the aircraft is loaded so as to be within the weight limitations and the balance limitations for intended operations. Commercial operators are usually required to complete a weight-and-balance form before takeoff. That form typically must then be retained for a period of time and available for inspection by regulating authorities. Weight is not just the overall weight limited by aircraft performance, but also limits imposed by the aircraft structure. For large aircraft, there is a max weight for taxi, another slightly lower for takeoff, another for max zero fuel weight, and another for max landing weight. Each of these maximums may also include separate operating envelopes for each condition that express the forward and aft limits of the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The center of gravity is typically expressed in percent of the mean aerodynamic chord, often shown as %MAC. Large aircraft typically have a recommended %MAC for the zero fuel weight for optimal operaton.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-01-09T01:43:04.227" LastActivityDate="2014-01-09T01:43:04.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="774" PostTypeId="4" CreationDate="2014-01-09T00:49:36.273" Score="0" Body="Weight-and-balance is determining that an aircraft is loaded within the limits of it's weight carrying capability and that the center of gravity is within the operational envelopes of the aircraft." OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-01-09T01:43:07.713" LastActivityDate="2014-01-09T01:43:07.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="775" PostTypeId="1" AcceptedAnswerId="776" CreationDate="2014-01-09T00:55:53.507" Score="14" ViewCount="18827" Body="&lt;p&gt;I know pilots can substitute WINGS phases for the Flight Review otherwise required every two years. How do I do this? Do I have to attend a class to meet all the equivalency requirements?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="97" LastEditDate="2014-01-13T01:12:38.460" LastActivityDate="2014-01-13T01:12:38.460" Title="How do I use the FAA's WINGS program as a flight review?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;&lt;faa-wings-program&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="776" PostTypeId="2" ParentId="775" CreationDate="2014-01-09T01:28:20.937" Score="14" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faasafety.gov/WINGS/pub/learn_more.aspx&quot;&gt;FAA Safety Team's WINGS program&lt;/a&gt; allows pilots to bypass the traditional &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY%5CRGFAR.NSF/0/8E5FD1956A15733586256959004BB274?OpenDocument&quot;&gt;FAR 61.56&lt;/a&gt; flight review by completing a &quot;phase&quot; of the WINGS program.  The program and requirements are detailed in FAA Advisory Circular 61-91 &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac%2061-91j.pdf&quot;&gt;(currently 61-91J)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short version is that a &quot;phase&quot; of WINGS consists of three credits of &quot;flight activities&quot; and three credits of &quot;knowledge activities&quot;, which must be earned with a 12 calendar month period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight credits are earned by flying with an instructor and demonstrating safe &amp;amp; proficient flying skills in specific areas of operation.&lt;br&gt;&#xA;For example, one &quot;Basic WINGS&quot; flight activity (worth 1 credit) is demonstrating basic air work - forward slips, steep turns, rectangular course, S-turns, and turns around a point - to Private Pilot practical test standards.&lt;br&gt;&#xA;When you have successfully completed a flight activity your instructor can log in to the FAA Safety / WINGS site and give you credit for completing the activity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowledge credits are earned by attending seminars and classes - these can be &lt;a href=&quot;https://faasafety.gov/SPANS/events/EventList.aspx&quot;&gt;in-person seminars set up by the FAA Safety Team&lt;/a&gt;, or on-line webinars.  Many of the &lt;a href=&quot;http://www.aopa.org/asf/online_courses/&quot;&gt;AOPA Air Safety Institute online courses&lt;/a&gt; qualify for WINGS credit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you complete a phase of wings your flight review clock resets, and your flight review becomes due 24 calendar months from the date you completed that phase.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ultimately participating in the WINGS program probably means you will be spending &lt;em&gt;more&lt;/em&gt; than the &quot;bare minimum&quot; 1 hour of ground time and 1 hour of flight time that FAR 61.56 requires. While you can often complete flight activities in an hour (or much less if you're proficient) the knowledge topics often take longer: the webinars are typically 30-40 minutes each, and in-person seminars can easily last an hour or more.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major benefit to the WINGS program is increased safety through building your knowledge and proficiency - the seminars are actually informative (and the in-person ones can even be fun, depending on who is running them), and the flight activities are pretty easy (though there are certainly challenging ones available if you want to push yourself and really sharpen your skills). Resetting the flight review is an enticement to encourage all of us to participate.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-09T01:28:20.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="777" PostTypeId="1" AcceptedAnswerId="788" CreationDate="2014-01-09T01:30:17.203" Score="25" ViewCount="5551" Body="&lt;p&gt;With 2,000hrs of flight time, a commercial ticket for ASEL and AMEL, CFI, CFII, MEI, and a Master's in Aeronautical Science I could easily qualify to fly right seat for a regional airline, but I just can't compete with pilots willing to work for \$17k/yr. For comparison, federal minimum wage is &lt;a href=&quot;http://poverty.ucdavis.edu/faq/what-are-annual-earnings-full-time-minimum-wage-worker&quot;&gt;currently just over $15K/yr&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are the starting salaries at US Regional Airlines so low?&lt;br&gt;&#xA;It seems odd that pilots go through extensive training which takes a great deal of time and expense, but they have to be prepared to work for what is a very low salary compared to other jobs that require a high level of skill and education.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supply and demand is one explanation, but I really don't understand how there is so much competition for flying jobs but at the same time there is a supposed &quot;pilot shortage&quot;.&lt;br&gt;&#xA;Are there really so many pilots out there that the competition for jobs drives down starting salaries so low?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am hoping to understand why it is that well-qualified pilots appear to have so little earning power in the marketplace.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="69" LastEditDate="2014-05-14T15:59:53.453" LastActivityDate="2014-09-30T17:48:34.513" Title="Why are US Regional Airline starting wages so low?" Tags="&lt;airline-operations&gt;&lt;career&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="778" PostTypeId="2" ParentId="777" CreationDate="2014-01-09T01:43:22.683" Score="21" Body="&lt;p&gt;Well, the short version is: The airlines pay what they have to pay in a free market.  They can get away with it because pilots are willing to accept it.  Like any other &lt;em&gt;business&lt;/em&gt; they are in it to make money and keeping costs down is just as good as making extra money, so they aren't going to volunteer anything extra.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, why do pilots do it?  Because of the promise of better things down the road.  It isn't as good as it used to be, but after being at the airlines for a few years, you can make a livable wage and as you get further into your career at a major airline, you still get paid pretty well for a &quot;part time&quot; job.  As I've heard other pilots say before:  It's better than a &quot;real&quot; job!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other pilots do it just because they love it and can't imagine doing anything else! &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-09T01:43:22.683" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="779" PostTypeId="2" ParentId="561" CreationDate="2014-01-09T01:47:53.520" Score="3" Body="&lt;p&gt;Good photos, but there are many indirect wind indicators that can affect aircraft especially when in close proximity to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One I experienced between Whitehorse and anchorage at about FL330 was a 9° temperature rise. A couple minutes later I flew into sever turbulence for about 30 seconds. The turbulence stopped and the temperature went back down. I was above an overcast and clear above but I could see through a small hole in the clouds some mountain tops. I check a chart and there was a mountain about 18 thousand feet tall. I figured that the cause was mechanical lifting of the jet stream over the mountains and I few through the burble on the backside of the mountain which cased the temperature to rise. So be very careful around mountains, things can happen with or without clouds as show in another comment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other things to look for that a lot of pilots may not be aware of is to learn the surroundings of the airports that you intend on flying into even your home base. Look for major features that could have an affect on wind. For example Hot Springs, VA has a mountain top airport and the wind blows upward and over the far end of the runway and then down to the runway a few thousand feet toward to departure end. What effect the wind has on an airplane as it enters the null area of little wind is that there is little acceleration on the airspeed indicator. The airspeed indicator also indicates the effect of the wind over your wings which can be very interesting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are close to large bodies of water and the airport is within a couple of mile from the water there can be very strong changes in the wind direction. I was on final at 3000 ft. with a strong wind from the right with a crab that caused me to view the runway through my side window. As I descended to within about 600 ft. I got into lake effect wind and ended up turning the airplane about 60° left to keep lined up with the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look for quarries and undulating land features that can indicate airflow. You cannot see the air but you can certainly see the land features that will give you a pretty good idea what to expect. Just this last weekend a corporate jet, after making a go around in Aspen tried to land on the second attempt and crashed. The wind was from the northwest 15 gusting to 25 kts. Aspen has a large mountain just to the west side of the runway and the pilot was attempted a down hill landing with the far end of the runway 200 ft. lower than the approach end which is at the max allowable of 2%. Aspen id 7800' AGL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a lot of wind gotcha's out there, this is a good topic keep them coming guys.&lt;/p&gt;&#xA;" OwnerUserId="400" LastActivityDate="2014-01-09T01:47:53.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="780" PostTypeId="2" ParentId="753" CreationDate="2014-01-09T02:00:30.213" Score="-2" Body="&lt;p&gt;Big airplanes of the jet types have what is called stick shakers to warn pilots of an approaching stall and a stick pusher to initiate a recovery. In training with jets most pilots do 100% of there training in simulators and then make three takeoff's and landings in the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;T tail airplanes may not be able to recover from stalls if the airplane get into a deep stall because airflow over the tail is blocked by the airplane and the elevator becomes ineffective.&lt;/p&gt;&#xA;" OwnerUserId="400" LastActivityDate="2014-01-09T02:00:30.213" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="781" PostTypeId="2" ParentId="751" CreationDate="2014-01-09T02:13:18.183" Score="5" Body="&lt;p&gt;If you go into any big airport you had better be organized and prepared. First of all be alert with you communications, ATC gives instructions once and expects you to understand what is being said and that expect you to do it, they may not have the time for seconds. The more they have to work with pilots that do not know the airport or procedures only loads the system and sets up hazard situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once on the ground have an airport diagram chart open and read to use. I recommend that you have paper and pencil ready to copy a taxi clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are at airports like LGA they do not have the normal taxiway signs, the signage is painted in the runways and taxi ways and are difficult to see when the cockpit is low to the ground. Especially when crossing runways that have crowns, Good luck in night conditions. The big airplanes with pilots that se 20 feet above the airport do not have that problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than that, no problem.&lt;/p&gt;&#xA;" OwnerUserId="400" LastActivityDate="2014-01-09T02:13:18.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="782" PostTypeId="1" AcceptedAnswerId="783" CreationDate="2014-01-09T02:15:08.170" Score="13" ViewCount="4594" Body="&lt;p&gt;I know it's a bit odd, but I like using my TI-89 graphing calculator in addition to an E6B when doing calculations. It helps me avoid dumb arithmetic errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read the section &quot;Use of Test Aids and Materials&quot; of  &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_guides/media/rec_private_pilot_ktg_oct2013.pdf&quot;&gt;Recreational Pilot and Private Pilot Knowledge Test Guide (FAA-G_8082-17)&lt;/a&gt;. It seems to meet all of the requirements except (d), which I don't really understand:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The use of magnetic cards, magnetic tapes, modules, computer chips, or&#xA;  any other device upon  which pre-written programs or information&#xA;  related to the test can be stored and retrieved is  prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does anyone have a definitive answer on whether these types of calculators are permitted?&lt;/p&gt;&#xA;" OwnerUserId="401" LastEditorUserId="69" LastEditDate="2014-01-18T17:54:06.860" LastActivityDate="2014-01-18T17:54:06.860" Title="Are TI graphing calculators permitted on the FAA knowledge exams?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="783" PostTypeId="2" ParentId="782" CreationDate="2014-01-09T02:23:01.663" Score="9" Body="&lt;p&gt;The document you cite actually goes on to explain what the procedure is for calculators, and when testing centers can prevent you from using your own (you'll be provided a loaner):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Testing centers may provide a calculator to you and/or deny use of your personal calculator based on the following limitations:&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;a. Prior to, and upon completion of the test, while in the presence of the Unit Member (formerly referred to as proctor), you must actuate the ON/OFF switch and perform any other function that ensures erasure of any data stored in memory circuits.&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;b. The use of electronic calculators incorporating permanent or continuous type memory circuits without erasure capability is prohibited. The Unit Member may refuse the use of your calculator when unable to determine the calculator’s erasure capability.&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;[...]&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, you can bring a graphing calculator and wipe it, but unless the center is able to confirm that you've removed all stored memory, they're probably just gonna say &quot;nah&quot; and hand you a basic calculator. There's a pretty good chance that your graphing calculator falls under the &quot;permanent or continuous type memory circuits&quot; category anyway.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-09T02:23:01.663" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="784" PostTypeId="2" ParentId="766" CreationDate="2014-01-09T02:59:49.793" Score="0" Body="&lt;p&gt;I really depends on what kind of aircraft we are talking abut. All the additional avionics @DeltaLima already has mentioned correctly effect aircraft with a MTOM of 5700kg or greater. If you think about some smaller G/A planes like a Cherokee or Skyhawk you should consider additional noise abatement. If you don't fulfill some requirements regarding noise abatement you will most probably spend a lot more money on landing fees or even meight be not allowed to land at some airports. I honestly don't know about noise regulations for bigger aircraft, but I guess that the differences between the US and Europe at this point are most significant at light types.&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-09T02:59:49.793" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="785" PostTypeId="2" ParentId="765" CreationDate="2014-01-09T03:51:06.497" Score="0" Body="&lt;p&gt;It's more or less the same as in a car. For me as a pilot a turbo- or supercharged engine is a absolute advantage - to have more power is sometimes really useful and also benefits the safety or it's just for fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For everyone whos not sure about the working principle of these systems or the difference between a turbocharger and a supercharger I will give a short description:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both are compressors installed in the manifold wich are used to get more air or air-fuel mixture into the engine or simply raise the density, which especially at higher altitudes provides some extra power. The difference between both is the way the compressors are driven.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A Turbocharger&lt;/strong&gt; is driven by a turbine in the exhaust. That's very efficient because it uses some of the ~ 70% wasted energy in a piston engine but also creates some back pressure on the exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A supercharger&lt;/strong&gt; is like other auxiliaries, e.g. the engine fuel pump, driven by the engine it self wich of cause costs a bit of engine efficiency but all in all the engine benefits from the installation. The great advantage compared to a turbocharger is that a supercharger works fine at all RPMs while a turbocharger needs some higher exhaust pressure to start working properly which makes it effective only at high power settings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot you don't need to take care of some additional switches but must of cause treat your engine a little bit different (higher risk to overpower). Do not use intermittent throttle position during take off or climb - allways go full forward. The use of intermittent throttle positions only causes your engine to work at higher load and non optimal cooling for longer time. If RPM exceedslimits reduce the Prop pitch carefully - rapidly lowering the RPM can cause severe damage to the engine! If you are used to lean mixture on the ground, stick to it your engine (the spark plugs) will be thankful but go full mixture for take off, even at some higher altitudes to achive maximum internal cooling of the cylinders - monitor the temperatures. These are some general suggestions based on my experience and knowledge, please refer always to the manual!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another risk I can thin of is, that you might be not used to flying at higher altitudes or VFR 'over the tops'. Try both with an instructor or experienced pilot first before doing it solo. You might be healthy and never had problems with your medical, anyway you should be able to lear how your body behaves. Also you might not be used to flying without the normal horizon - this might be lost when descending or climbing in VMC but in close vicinity of clouds. It's not my intention to consider you as unexperienced but I like to write this answer in a way, that it's helpful for everyone whos interested in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operator or owner of an aircraft should not only consider the advantages of forced ignition. Before I've edited this answer I wrote, that piston engines are nlt developed to be turbo/supercharged. This way to say it was obviously not really helpfull for you, sorry. What I want you to think of are the additional loads acting on the engine. You have high pressure within the cylinders,  even some back pressure on the exhaust (turbocharger only) or additional friction to drive the supercharger. The engines whitch are equipped with forced ignition or those where turbochargers are available fore of cause are built to handel these forces but I still consider them to effect the life of those engines. So there are definitely more extra costs then the purchase of the equipment.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-01-09T23:12:21.520" LastActivityDate="2014-01-09T23:12:21.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="786" PostTypeId="1" AcceptedAnswerId="857" CreationDate="2014-01-09T11:25:28.590" Score="36" ViewCount="5920" Body="&lt;p&gt;Note before reading further that I'm asking this question purely on theoretical grounds, though you are more than welcome to talk about practical aspects as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, my question. It's common knowledge amongst many pilots that turnbacks are one of the least safe methods of attempting to survive an engine failure in a single engine aircraft. However, is it actually possible at all to turnback an aircraft to return to the airport perimeter or the runway? How much of it is simply pilot error in executing a possible manoeuvre, as opposed to pilots thinking that they can pull something off that is just impossible, no matter what?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purposes of this question, we shall assume the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;there is only one runway, so a reciprocal turn is required (we shall assume 210 degrees)&lt;/li&gt;&#xA;&lt;li&gt;the aircraft has a flaps up stall speed at MTOW of 75 knots&lt;/li&gt;&#xA;&lt;li&gt;the aircraft has a best glide ratio of 1:12 at 100 knots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Alternatively, if you have any other information that is more akin to a real aircraft, you can use that in lieu of this information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources or an explanation as to why this it is or isn't impossible would be appreciated in your answers.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="247" LastEditDate="2014-07-07T05:42:36.320" LastActivityDate="2018-11-05T04:54:36.137" Title="Is it even remotely feasible to turnback a single engine aircraft with an engine failure?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;accidents&gt;&lt;single-engine&gt;&lt;engine-failure&gt;" AnswerCount="10" CommentCount="10" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="787" PostTypeId="2" ParentId="786" CreationDate="2014-01-09T14:32:07.623" Score="16" Body="&lt;p&gt;It is &quot;remotely feasible&quot;, you can watch &lt;a href=&quot;https://www.youtube.com/watch?v=t6v45p9liIc&quot; rel=&quot;nofollow noreferrer&quot;&gt;this pilot story&lt;/a&gt; from AOPA about someone who did it. But, that doesn't mean that you or anyone else will be successful in attempting it because of the large number of variables that you mentioned. And one successful execution does not mean that it's a good idea in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One suggestion I've read several times is to try it yourself in the air: set the 'ground' at say 3000agl then try it out with whatever aircraft configurations you like and see what the results are. But even if you pull it off in those conditions, will you do it again in a real situation with the added stress and possibly additional weight (passengers, luggage) in the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, based on everything I've read and been told, it's called the impossible turn for a reason. My training anecdote from an instructor was a local pilot flying with his son who tried it, made the turn but stalled out, crashed on the runway, made it out of the aircraft but then had to watch his son burn to death in the wreckage. That sort of story makes a landing in a field or even a street seem very attractive, which was exactly my instructor's intention.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22864" LastEditDate="2018-06-09T01:33:05.630" LastActivityDate="2018-06-09T01:33:05.630" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="788" PostTypeId="2" ParentId="777" CreationDate="2014-01-09T15:23:29.357" Score="11" Body="&lt;p&gt;You need to look at turn-of-the-century early industrial age history for your answer.  Factories were filled with skilled workers who could weave or smith or do some other specialty with great speed.  These were not unskilled workers by modern standards, but their skills were common in those days.  The efficient factories lowered prices for those products, making those skills less valuable.  The workers were dependent on that factory for their livelihood, they could not easily find work outside the factory.  If they grew up in that factory town, they likely had no other skills.  There were few factories of their kind they could work in, and no unions or labor laws.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airline pilots are in a similar situation.  While airline mechanics can quit and maintain power plants or trucks with a little training, pilots are stuck with now three major airlines and a handful of regional airlines.  They have no skills that can cross over to another industry.  Their unions cannot strike or even hint at a job action expressing their discontent.  But the airlines can outsource their jobs to cheaper pilots, and have done so with over half their pilot jobs over the past decade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those cheaper pilots are disappearing, as the major airlines start hiring, and young people realize what the career of an airline pilot has become.  This has been leading up to a pilot shortage for many years, and the efforts to stave off that shortage have resulted in fewer pilots getting trained every year.  The result will certainly be a wave of much higher pay, but it won't change the underlying cause.  The wave of young people who rush into the career when the pay skyrockets will certainly see their pay drop again, along with layoffs and working the bottom jobs, when the airlines have enough pilots and hit another down decade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oh, and $17k is a little more than Skywest, Republic, American Eagle, Great Lakes, and other entry-level carriers pay their new-hires for the first several years.  Sorry.&lt;/p&gt;&#xA;" OwnerUserId="425" LastActivityDate="2014-01-09T15:23:29.357" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="789" PostTypeId="2" ParentId="786" CreationDate="2014-01-09T15:33:11.997" Score="8" Body="&lt;p&gt;The reason that we are trained to simply not turn back is the same reason we memorize and drill the instant action items in emergency checklists. When the stuff hits the fan, you don't have time to think about all the possibilities of your actions. Your initial response time is critical to a successful outcome. Especially when you're already low and slow. And in an actual emergency situation, your chances of responding correctly are severely diminished if you have to think about what you're doing. You should KNOW what you'll do before it happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V_1$ cuts in a multi-engine aircraft are a great example of making an instant decision that may seem counter-intuitive. If an engine stops before you hit $V_1$ speed, you abort. Otherwise, you know for a fact that once you reach $V_1$ speed, you will continue that takeoff, even if one of your engines fail. You'll deal with the emergency in the air, where it's safer and you have time to run the drill. Turning back to the airport falls into the same category. Turning back may seem attractive, but if you're still in takeoff phase, your chances of success are much smaller if you try a tight bank in a slow, low aircraft.  &lt;/p&gt;&#xA;" OwnerUserId="383" LastEditorUserId="97" LastEditDate="2014-04-16T23:54:56.863" LastActivityDate="2014-04-16T23:54:56.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="790" PostTypeId="2" ParentId="786" CreationDate="2014-01-09T16:06:28.487" Score="12" Body="&lt;p&gt;There's a very good discussion of the &quot;impossible turn&quot; at the following link:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nar-associates.com/technical-flying/impossible/possible.html&quot;&gt;http://www.nar-associates.com/technical-flying/impossible/possible.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It goes into an AIAA study using a flight simulator with new and experienced pilots and it shows that while it's technically feasible, pilots need to train for it and be very strict with their bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a lot of detail in the link that's hard to summarize, but the gist is that most untrained pilots fail and crash in a simulator, so unless you've practiced it, it's not worth trying.&lt;/p&gt;&#xA;" OwnerUserId="21" LastActivityDate="2014-01-09T16:06:28.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="792" PostTypeId="2" ParentId="200" CreationDate="2014-01-09T17:11:13.207" Score="0" Body="&lt;p&gt;Of all the challenges in aviation, ice is probably the scariest, no matter the size of the airplane. It can ruin your day REAL fast if you don't deal with it properly. Bigger aircraft usually have better systems / support personnel to deal with it, but it still needs to be dealt with on smaller aircraft. If you're still on the ground, remove it completely. From every surface. Use deice fluid to get rid of it (or a heated hangar), and if the accumulation is such that it keeps returning quickly, anti-ice solution can work. But this level of icing should definitely factor into your No-Go decision. &lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2014-01-09T17:11:13.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="793" PostTypeId="2" ParentId="764" CreationDate="2014-01-09T17:35:26.367" Score="8" Body="&lt;p&gt;This depends on what you mean by a &quot;jetpack&quot;. If you mean the classic James Bond-style rocket pack, then according to an FAA spokesman &lt;a href=&quot;http://online.wsj.com/news/articles/SB123655460908765815&quot;&gt;quoted&lt;/a&gt; in the Wall Street Journal they just don't fly long enough for the FAA to be interested:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once aloft, a jetpack pilot is preoccupied with getting down quickly:&#xA;  A typical pack holds about 10 gallons of fuel, only enough to fly for&#xA;  about half a minute. The Federal Aviation Administration doesn't&#xA;  regulate jetpacks. &quot;Thirty seconds is not sufficient to be considered&#xA;  a flight,&quot; says FAA spokesman Les Dorr. He adds that it's up to the&#xA;  individual to assess the risks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the other hand if you're referring to the &lt;a href=&quot;http://www.martinjetpack.com/&quot;&gt;Martin Jetpack&lt;/a&gt;, which uses fans instead of rockets, then several sources (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Martin_Jetpack&quot;&gt;Wikipedia&lt;/a&gt;) say that it's considered an ultralight by the FAA, in which case all the usual ultralight regulations would apply. But I couldn't find any direct confirmation of that on Martin's site.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-09T17:35:26.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="794" PostTypeId="2" ParentId="738" CreationDate="2014-01-09T18:53:09.253" Score="11" Body="&lt;p&gt;I spend a bit of time using a flight sim (Lockheed-Martin's Prepar3D).  I have discussed this very question with CFI's and there is some disagreement.  A flight sim cannot &quot;teach you to fly.&quot;  It can help you practice what you have learned in your flight lessons.  there are some caveats: 1) you have to have rudder pedals and a stick or yoke.  2) More monitors is better.  3) Using photorealistic scenery will get you more familiar with area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A home rig with the minimum &quot;bells and whistles&quot; can run up to $1,000 or more.  That's about 5 hours of real world flight lessons plus ground school (If you shop around).  You can learn A LOT in 5 hours of flight training.&lt;/p&gt;&#xA;" OwnerUserId="459" LastEditorUserId="39" LastEditDate="2014-01-10T21:31:08.713" LastActivityDate="2014-01-10T21:31:08.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="795" PostTypeId="2" ParentId="758" CreationDate="2014-01-09T19:15:15.203" Score="1" Body="&lt;p&gt;To answer your question simply with emphasis on continued cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your certificate never expires and never needs renewed.&#xA;There is no minimum hours required for life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only cost involved to become current is to hire a flight instructor for a flight review(FR). This isn't required every 2 years, but you must have had a FR within 2 years of operating as a private pilot. There is no test and no examiner for a FR. The only requirement is one hour of flight and one hour of ground training with an instructor of your choosing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only other cost involved to operate as a private pilot would be a medical certificate from a designated medical examiner. A private pilot can fly as a sport pilot without a medical under certain limitations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have the money/time now, and feel that it would more practical/better investment than waiting for costs to go up, than there is very little expense you would need to spend later.&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-01-09T19:15:15.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="796" PostTypeId="2" ParentId="786" CreationDate="2014-01-09T19:31:26.150" Score="1" Body="&lt;p&gt;The answer is yes and no. If at a sufficient altitude, a return to the airport is feasible. If a suitable landing spot is in front of you that is the best option. You MUST know your aircrafts limitations and your skill level to determine when it is safe to return to the airport.&lt;/p&gt;&#xA;" OwnerUserId="461" LastEditorUserId="39" LastEditDate="2014-01-09T20:36:48.563" LastActivityDate="2014-01-09T20:36:48.563" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="798" PostTypeId="5" CreationDate="2014-01-09T20:15:08.393" Score="0" Body="&lt;p&gt;Airspace in general refers to the air - or atmosphere - above a specific country or other ground area, e.g. US airspace, Washington DC airspace, etc. For aviation purposes airspace is classified and divided in various ways; these classifications are broadly similar in most countries but the details can vary. Operating in various types of airspace usually requires the pilot to follow certain rules or have certain training, and some airspace may be completely closed to air traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One important classification is the airspace &lt;em&gt;class&lt;/em&gt;, which is lettered from A to G (&lt;em&gt;class A&lt;/em&gt;, &lt;em&gt;class B&lt;/em&gt; etc.) although not all classes exist in all countries.  Class A is the most restrictive and class G the least restrictive.  Each airspace class has different rules for who can operate in them and in which circumstances, e.g. class A in the US is limited to &lt;a href=&quot;/questions/tagged/instrument-flight-rules&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;instrument-flight-rules&amp;#39;&quot; rel=&quot;tag&quot;&gt;instrument-flight-rules&lt;/a&gt; flights only.  See &lt;a href=&quot;/questions/tagged/airspace-classes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspace-classes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspace-classes&lt;/a&gt; for questions about these classes and the differences between them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second classification is &lt;em&gt;special use airspace&lt;/em&gt;, which covers many different designations including prohibited airspace, restricted airspace, military training zones and others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airspace classes and uses are clearly marked on aviation charts, although temporary and even permanent changes may be made at any time for security or other reasons. Understanding airspace types and their associated rules is important for all pilots.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airspace_class&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airspace class&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/TOC.html#Chapter%203.%E2%80%82Airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;US FAA AIM chapter on airspace&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2018-05-10T19:55:00.387" LastActivityDate="2018-05-10T19:55:00.387" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="799" PostTypeId="4" CreationDate="2014-01-09T20:15:08.393" Score="0" Body="Airspace means the air above a specific country (e.g. US airspace) but for aviation purposes it is usually divided into different types, each of which may have different regulations." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-09T22:01:51.200" LastActivityDate="2014-01-09T22:01:51.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="800" PostTypeId="1" AcceptedAnswerId="807" CreationDate="2014-01-09T20:15:20.550" Score="13" ViewCount="6317" Body="&lt;p&gt;Mechanical and hydro-mechanical flight control systems (cables, pushrods, hydraulics) all offer pilots some form of feedback – direct or, in the case of hydraulics, artificial – as the aircraft maneuvers and forces are applied to the controls.  I know that early FBW, like that in the &lt;a href=&quot;http://en.wikipedia.org/wiki/F-16#Cockpit_and_ergonomics&quot;&gt;F-16 prototypes&lt;/a&gt;, used a rigid system that often allowed pilots to over-control the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do &lt;a href=&quot;http://en.wikipedia.org/wiki/Fly-by-wire&quot;&gt;fly-by-wire&lt;/a&gt;-equipped airliners, like their non-FBW siblings, use an artificial feel system to provide control feedback?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-09T22:38:06.213" LastActivityDate="2018-01-18T03:32:18.207" Title="Do fly-by-wire flight controls in airliners provide artificial feel?" Tags="&lt;flight-controls&gt;&lt;fly-by-wire&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="802" PostTypeId="2" ParentId="738" CreationDate="2014-01-09T21:42:47.370" Score="19" Body="&lt;p&gt;I spent a lot of time (years) flying MSFS before getting into a cockpit for real. Turns out I had developed a bad habit of using the instruments rather than my eyes. When simming I probably spent 80% of my time looking at instruments and the moving map and only 20% looking outside. The biggest surprise for me about IRL flying was that these ratios were reversed, at least in VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now being a pilot it is very helpful for practicing procedures, test-flying cross countries, and, with the ground detail in FSX, practicing navigating by reference to ground features (e.g. &quot;IFR&amp;amp;R&quot;: I Follow Roads and Railroads).&lt;/p&gt;&#xA;" OwnerUserId="352" LastActivityDate="2014-01-09T21:42:47.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="804" PostTypeId="5" CreationDate="2014-01-09T23:15:44.627" Score="0" Body="&lt;p&gt;Flight planning is the process of preparing for a flight by gathering, calculating and documenting all necessary information about the route, weather and the aircraft itself. Typically this includes (at least) the following activities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Identifying a route to fly and the appropriate navigation method(s) to use&lt;/li&gt;&#xA;&lt;li&gt;Selecting alternate landing airfields in case a diversion is required&lt;/li&gt;&#xA;&lt;li&gt;Calculating how long each leg of the flight will last&lt;/li&gt;&#xA;&lt;li&gt;Calculating the fuel required&lt;/li&gt;&#xA;&lt;li&gt;Checking weather forecasts and the possible effects on the flight&lt;/li&gt;&#xA;&lt;li&gt;Calculating the weight that will be loaded on board the aircraft&lt;/li&gt;&#xA;&lt;li&gt;Checking TFRs, NOTAMs and other information that may affect the flight&lt;/li&gt;&#xA;&lt;li&gt;Preparing and filing a flight plan&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Many of these activities are related, e.g. poor weather may require a different, longer route that increases the time and fuel required for a flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;General aviation pilots usually plan flights themselves; airlines employ flight dispatchers to plan flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for any of the activities mentioned above, and in general for any planning activity that takes place before a flight departs.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_planning&quot; rel=&quot;nofollow&quot;&gt;Flight planning&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_planner&quot; rel=&quot;nofollow&quot;&gt;Flight planner&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-09T23:30:41.987" LastActivityDate="2014-01-09T23:30:41.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="805" PostTypeId="4" CreationDate="2014-01-09T23:15:44.627" Score="0" Body="Flight planning is the process of preparing for a flight: planning a route to fly, identifying alternate destinations in case of diversion, calculating required fuel, ensuring the aircraft will not be not overloaded and so on." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-09T23:30:50.270" LastActivityDate="2014-01-09T23:30:50.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="806" PostTypeId="2" ParentId="800" CreationDate="2014-01-10T00:02:26.997" Score="0" Body="&lt;p&gt;To answers this question I need to remember my favourite subject, Principles of Flight - just kidding. The key to the aswer is the requirement that civil (sorry, I don't know about military, but you're also not asking) aircraft are required to have a certain amount of stick force per G. What does this mean? In simple words:the aircraft is required to require the pilot to put more force on the controls if he wants to achive a higher load factor. Even simpler: we are supposed to work hard to have fun ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we need to know what fly by wire is. FBW means that the imputs from the pilots are brought to the control surfaces, or better the actuators digital. So there is no mechanical connection between the surfaces, where the aerodynamic forces act and the controls the pilot feels. That means that there are also no stick forces per G. That would also make a pilots life very hard. I can not imagine to fly a plane without feeling it / getting a feedback on the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking into account both facts I've listed above my answer is yes, an airliner which is fly by wire equipped needs also to be equipped with an artificial feel system.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-01-10T00:07:38.833" LastActivityDate="2014-01-10T00:07:38.833" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="807" PostTypeId="2" ParentId="800" CreationDate="2014-01-10T00:14:21.327" Score="8" Body="&lt;p&gt;After some digging, I found an answer for myself: &lt;strong&gt;yes, some FBW airliners use artificial feel systems, but not all of them&lt;/strong&gt;. According to &lt;em&gt;&lt;a href=&quot;http://books.google.com/books?id=EumPJQBViz4C&amp;amp;lpg=PA167&amp;amp;ots=HTgROzbAa0&amp;amp;dq=boeing%20fly%20by%20wire%20%22artificial%20feel%22&amp;amp;pg=PA167#v=onepage&amp;amp;q=boeing%20fly%20by%20wire%20%22artificial%20feel%22&amp;amp;f=false&quot;&gt;Electronics in the Evolution of Flight (Google Books)&lt;/a&gt;&lt;/em&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The [Boeing] 777 fly-by-wire system employs &lt;em&gt;envelope protection.&lt;/em&gt; This feature of the artificial-feel system provides increasingly greater force when the aircraft is pushed to its limits.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Conversely, Airbus does not provide any feedback to the pilots as their flight control system enforces control laws that cannot be overridden by inputs (source: &lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_12.pdf&quot;&gt;Aerospatiale engineering document&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The positioning of the control surfaces is no longer a simple reflection of the pilot’s control inputs and conversely, the natural aerodynamic characteristics of the aircraft are not fed back directly to the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Getting regulatory, since I did some further research: 14 CFR 29.395, certification of Transport Category aircraft, only &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=481d44507e861a5d391dace19a071d4a&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.14&amp;amp;idno=14#14:1.0.1.3.14.3.329.13&quot;&gt;states that the controls are required to &lt;em&gt;resist&lt;/em&gt; a certain amount of force&lt;/a&gt; (i.e., not break). This differs from how much force is required to &quot;achieve the positive limit maneuvering load factor&quot; or otherwise impart changes to the aircraft's orientation (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=cf1ebd59dcb997f14447306b34545796&amp;amp;node=14:1.0.1.3.10.2.62.31&amp;amp;rgn=div8&quot;&gt;14 CFR 23.155&lt;/a&gt; / &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=cf1ebd59dcb997f14447306b34545796&amp;amp;r=SECTION&amp;amp;n=14y1.0.1.3.10.2.62.32&quot;&gt;23.157&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-10T03:15:35.900" LastActivityDate="2014-01-10T03:15:35.900" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="808" PostTypeId="1" CreationDate="2014-01-10T01:06:15.817" Score="22" ViewCount="1302" Body="&lt;p&gt;While asking the question in chat &lt;em&gt;How do we get controllers on the site?&lt;/em&gt; &lt;a href=&quot;http://chat.stackexchange.com/transcript/message/13099918#13099918&quot;&gt;@egid suggested&lt;/a&gt; there may be FAA or union restrictions on participating in Q&amp;amp;A. That would be sad since pilots and controllers communicating with each other improves safety and efficiency... but certainly doesn't mean it isn't true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know of specific restrictions placed on controllers by the FAA or NATCA (National Air Traffic Controllers Association) which would prevent them from answering questions on this site?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I realize this blurs the line slightly between the main site and &lt;a href=&quot;https://aviation.meta.stackexchange.com/&quot;&gt;meta&lt;/a&gt;, but I'm asking about legal reasons, not speculation about why we haven't attracted any controllers yet (that I'm aware of).&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-03-16T15:52:28.310" LastActivityDate="2016-04-12T18:30:56.597" Title="Can Air Traffic Controllers participate in Q&amp;A?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="809" PostTypeId="1" AcceptedAnswerId="813" CreationDate="2014-01-10T01:53:18.803" Score="22" ViewCount="19293" Body="&lt;p&gt;Coast patrol has a dedicated frequency for emergency that must be watched at almost all hours, and even if I recall, it had a &quot;dead silent period&quot; to prioritise whatever emergency might be reported. Is there a dedicated frequency for aviation? Or shall MAYDAYs just be sent to the standard ATC frequency?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="69" LastEditDate="2014-01-13T01:53:22.000" LastActivityDate="2014-10-18T01:26:38.040" Title="Is there a dedicated emergency frequency?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;radio-communications&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="810" PostTypeId="2" ParentId="809" CreationDate="2014-01-10T01:57:34.173" Score="20" Body="&lt;p&gt;Yes, the aircraft emergency frequency (which we often call &quot;guard&quot;) is 121.5 MHz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is monitored by many control towers and flight service stations. It is also typically monitored by airplanes on cross-country trips (especially airliners). You will occasionally hear ATC ask an airplane to try to contact another airplane &quot;on guard&quot; in an attempt to relay a message to an aircraft which they have lost communications with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you are currently in communication with ATC on another frequency, or there is a frequency where you know you can communicate your distress and it will be heard, you should use that frequency instead, because there is no guarantee your message will be heard on 121.5 in all parts of the country/world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older ELT's (emergency locator transmitter) also transmitted a siren type sound on this frequency when activated which &lt;a href=&quot;http://www.youtube.com/watch?v=I_AMzBuoLs0&quot;&gt;sounds like this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, it is used as an intercept frequency. In other words, if you get intercepted by a fighter jet, you better be listening in on 121.5 for any commands they give you.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2014-01-10T02:02:57.217" LastActivityDate="2014-01-10T02:02:57.217" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="811" PostTypeId="2" ParentId="809" CreationDate="2014-01-10T01:59:31.763" Score="6" Body="&lt;p&gt;As a general rule, declaring an emergency should be done on the frequency you are currently communicating on. However, there is a dedicated emergency frequency as Bret said (121.5 MHz), which is the same all over the world. It's generally used if there is no response from the ATC facility the pilot was communicating with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On many glass cockpits there's even a shortcut to tune to the emergency frequency. For example, on Garmin equipment like the G1000 and G530/430 you have to press and hold the &quot;flip-flop&quot; key for 2 seconds and it will automatically tune 121.5 for you.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-10T02:04:49.230" LastActivityDate="2014-01-10T02:04:49.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="813" PostTypeId="2" ParentId="809" CreationDate="2014-01-10T02:02:46.853" Score="27" Body="&lt;p&gt;If a pilot is already speaking to ATC (or monitoring a frequency) they should continue to use that frequency for any emergency or abnormal situation.&lt;/p&gt;&#xA;&lt;p&gt;If they are not currently receiving ATC services or on an ATC frequency, attempt to use 121.5. Many ATC providers and enroute airliners monitor this frequency and can relay or provide assistance.&lt;/p&gt;&#xA;&lt;p&gt;The FAA's &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0603.html&quot; rel=&quot;noreferrer&quot;&gt;AIM (6-3-1)&lt;/a&gt; describes emergency use of 121.5 in the United States:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;h. Although the frequency in use or other frequencies assigned by ATC are preferable, the following emergency frequencies can be used for distress or urgency communications, if necessary or desirable:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;1. 121.5 MHz and 243.0 MHz. Both have a range generally limited to line of sight. 121.5 MHz is guarded by direction finding stations and some military and civil aircraft. 243.0 MHz is guarded by military aircraft. Both 121.5 MHz and 243.0 MHz are guarded by military towers, most civil towers, FSSs, and radar facilities. &lt;strong&gt;Normally ARTCC emergency frequency capability does not extend to radar coverage limits.&lt;/strong&gt; &lt;em&gt;[emphasis mine]&lt;/em&gt; If an ARTCC does not respond when called on 121.5 MHz or 243.0 MHz, call the nearest tower or FSS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-10T02:45:18.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="814" PostTypeId="1" AcceptedAnswerId="818" CreationDate="2014-01-10T03:04:57.527" Score="14" ViewCount="10390" Body="&lt;p&gt;How do I get permission to fly an airplane with a non-safety-related airworthiness issue, like being out of annual or having an inoperative radio in order to take it somewhere that it can be fixed?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T17:03:47.020" LastActivityDate="2014-01-18T17:03:47.020" Title="How do I obtain permission to fly an airplane that isn't airworthy?" Tags="&lt;faa&gt;&lt;airworthiness&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="815" PostTypeId="1" AcceptedAnswerId="816" CreationDate="2014-01-10T03:07:53.073" Score="12" ViewCount="7365" Body="&lt;p&gt;At least where I fly, most instrument approaches now use a &lt;em&gt;Hold In Lieu of Procedure Turn&lt;/em&gt; (&lt;strong&gt;HILO&lt;/strong&gt;). The &quot;full procedure&quot; now consists of a turn in the hold before proceeding inbound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/P5PAO.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/P5PAOm.png&quot; alt=&quot;KPAE ILS Y RWY 16R (annotated)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the example above (click to embiggen), if a pilot is northeast of EYWOK and receives the following clearance from Seattle Approach:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cessna 123AB, proceed direct EYWOK, maintain 3000 until established, cleared for the ILS Yankee approach at Paine Field.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Are they &lt;strong&gt;required&lt;/strong&gt; to fly the course reversal, or can they proceed inbound on the final approach course immediately upon reaching EYWOK and fly direct to ITIPE?  If not, what instruction must be received in order to skip the HILO procedure?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="72" LastEditDate="2014-03-03T05:32:08.437" LastActivityDate="2014-03-03T05:32:08.437" Title="When cleared for an approach and not on vectors, is a depicted course reversal always required?" Tags="&lt;air-traffic-control&gt;&lt;iaps&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="816" PostTypeId="2" ParentId="815" CreationDate="2014-01-10T03:12:12.793" Score="11" Body="&lt;p&gt;Yes, with this procedure you are required to fly the procedure turn unless you are flying the CVV transition (which is notated as NoPT), are receiving vectors to final, or receive a clearance for a &quot;straight-in approach&quot; over EYWOK.  If you are cleared direct to the final approach fix, none of these apply (but remember that you can always &lt;strong&gt;request&lt;/strong&gt; a &lt;em&gt;straight-in approach&lt;/em&gt; if you don't want to do the course reversal)!&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/66AFE97435E47B3A86256E1A00518D27?OpenDocument&quot;&gt;FAR 91.175&lt;/a&gt;&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(j) Limitation on procedure turns. In the case of a radar vector to a&#xA;  final approach course or fix, a timed approach from a holding fix, or&#xA;  an approach for which the procedure specifies &quot;No PT,&quot; no pilot may&#xA;  make a procedure turn unless cleared to do so by ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AIM states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot;&gt;5-4-6. Approach Clearance&lt;/a&gt;&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;4. If proceeding to an IAF with a published course reversal (procedure turn or hold­in­lieu of PT pattern), except when cleared for a&#xA;  straight in approach by ATC, the pilot must execute the procedure&#xA;  turn/hold­in­lieu of PT, and complete the approach.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5. If cleared to an IAF/IF via a NoPT route, or no procedure turn/hold­in­lieu of PT is published, continue with the published&#xA;  approach.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6. In addition to the above, RNAV aircraft may be issued a clearance direct to the IAF/IF at intercept angles not greater than 90 degrees&#xA;  for both conventional and RNAV instrument approaches. Controllers may&#xA;  issue a heading or a course direct to a fix between the IF and FAF at&#xA;  intercept angles not greater than 30 degrees for both conventional and&#xA;  RNAV instrument approaches. In all cases, controllers will assign&#xA;  altitudes that ensure obstacle clearance and will permit a normal&#xA;  descent to the FAF. When clearing aircraft direct to the IF, ATC will&#xA;  radar monitor the aircraft until the IF and will advise the pilot to&#xA;  expect clearance direct to the IF at least 5 miles from the fix. ATC&#xA;  must issue a straight­in approach clearance when clearing an aircraft&#xA;  direct to an IAF/IF with a procedure turn or hold-in-lieu of a&#xA;  procedure turn, and ATC does not want the aircraft to execute the&#xA;  course reversal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;7. RNAV aircraft may be issued a clearance direct to the FAF that is also charted as an IAF, in which case the pilot is expected to execute&#xA;  the depicted procedure turn or hold­in­lieu of procedure turn.  ATC&#xA;  will not issue a straight­in approach clearance.  If the pilot desires&#xA;  a straight­in approach, they must request vectors to the final&#xA;  approach course outside of the FAF or fly a published “NoPT” route. &#xA;  When visual approaches are in use, ATC may clear an aircraft direct to&#xA;  the FAF.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-10T05:18:25.653" LastActivityDate="2014-01-10T05:18:25.653" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="817" PostTypeId="2" ParentId="814" CreationDate="2014-01-10T03:23:29.767" Score="12" Body="&lt;p&gt;The FAA / Philidelphia FSDO already gave a &lt;a href=&quot;https://www.faa.gov/about/office_org/field_offices/fsdo/phl/local_more/media/ferry_permit.pdf&quot;&gt;perfect short and snappy official answer&lt;/a&gt; perfectly matching your question. &#xA;Please note the restrictions mentioned in this handy sheet to stay absolutely legal :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short summary: contact &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot;&gt;your local FSDO&lt;/a&gt; to request a Special Flight Permit (&quot;ferry permit&quot;), which are commonly used for:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flying the aircraft to a base where repairs, alterations, or maintenance are to be performed&lt;/li&gt;&#xA;&lt;li&gt;Flying an aircraft whose annual inspection has expired to a base where an annual inspection can be accomplished.&lt;/li&gt;&#xA;&lt;li&gt;Production flight testing of new production aircraft.&lt;/li&gt;&#xA;&lt;li&gt;To authorize the operation of an aircraft at a weight in excess of its maximum certificated takeoff weight.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;and many other reasons detailed in the link above.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To obtain a special flight permit you will need to provide the following info to the FAA:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Purpose of the flight.&lt;/li&gt;&#xA;&lt;li&gt;Proposed flight itinerary.&lt;/li&gt;&#xA;&lt;li&gt;Essential crew required to operate the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The ways, if any, in which the aircraft does not comply with the applicable airworthiness requirements.&lt;/li&gt;&#xA;&lt;li&gt;Any other information they may request&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="343" LastEditorUserId="64" LastEditDate="2014-01-10T16:08:46.063" LastActivityDate="2014-01-10T16:08:46.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="818" PostTypeId="2" ParentId="814" CreationDate="2014-01-10T03:23:40.700" Score="16" Body="&lt;p&gt;You must request a &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/sp_flt_permit/&quot;&gt;Special Flight Permit&lt;/a&gt; from the &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/locate_office/&quot;&gt;nearest FSDO&lt;/a&gt; (Flight Standards District Office).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll need to fill out &lt;em&gt;&lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/sp_awcert_regs/&quot;&gt;Form 8130-6&lt;/a&gt;, Application for U.S. Airworthiness&lt;/em&gt;, appropriately calling out the reasons you need a SFP (ferry flight, etc). Once the form is submitted, you may be subject to an inspection by an FAA official or representative, verifying that your aircraft is in fact &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/airworthiness_certification/cond_safe_oper/&quot;&gt;in a condition for safe operation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avemco, the insurance company, has &lt;a href=&quot;http://www.avemco.com/information/blogs/The-Facts-on-Ferry-Permits.aspx&quot;&gt;a good article on ferry permits&lt;/a&gt; that might be worth an extended read and which I don't intend to copy here.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-10T03:23:40.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="819" PostTypeId="1" CreationDate="2014-01-10T03:47:20.567" Score="16" ViewCount="1865" Body="&lt;p&gt;So, the Learjet 60 that I used to fly has the following limitation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/McK3V.png&quot; alt=&quot;Learjet 60 AFM page&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question, is &lt;strong&gt;why would&lt;/strong&gt; a manufacturer certify an airplane for ditching if it isn't required?  The airplane is most likely going to be totaled anyway, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or does it just mean that since it isn't certified for ditching that we aren't allowed to do it?  Guess no double engine failures over water will be in my near future....&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-01-13T01:10:01.523" LastActivityDate="2014-01-13T01:10:01.523" Title="Why would an airplane be approved for ditching?" Tags="&lt;aircraft-limitations&gt;&lt;afm&gt;&lt;far-25&gt;&lt;ditching&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="820" PostTypeId="2" ParentId="819" CreationDate="2014-01-10T03:54:43.050" Score="13" Body="&lt;p&gt;I think that &lt;a href=&quot;http://federal.eregulations.us/cfr/section/title14/chapterI/part25/sect25.801?selectdate=8/15/2013&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.801&lt;/a&gt; might sum this one up. Aircraft that are approved for ditching under 25.801 have to meet several requirements:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(b) Each practicable design measure, compatible with the general characteristics of the airplane, must be taken to minimize the probability that in an emergency landing on water, the behavior of the airplane would cause immediate injury to the occupants or would make it impossible for them to escape.&lt;/p&gt;&#xA;&lt;p&gt;(c) &lt;strong&gt;The probable behavior of the airplane in a water landing must be investigated by model tests&lt;/strong&gt; [&lt;em&gt;emphasis mine&lt;/em&gt;] or by comparison with airplanes of similar configuration for which the ditching characteristics are known. Scoops, flaps, projections, and any other factor likely to affect the hydrodynamic characteristics of the airplane, must be considered.&lt;/p&gt;&#xA;&lt;p&gt;(d) It must be shown that, &lt;strong&gt;under reasonably probable water conditions, the flotation time and trim of the airplane will allow the occupants to leave the airplane and enter the liferafts required by § 25.1415.&lt;/strong&gt; [&lt;em&gt;emphasis mine&lt;/em&gt;] If compliance with this provision is shown by buoyancy and trim computations, appropriate allowances must be made for probable structural damage and leakage. If the airplane has fuel tanks (with fuel jettisoning provisions) that can reasonably be expected to withstand a ditching without leakage, the jettisonable volume of fuel may be considered as buoyancy volume.&lt;/p&gt;&#xA;&lt;p&gt;(e) Unless the effects of the collapse of external doors and windows are accounted for in the investigation of the probable behavior of the airplane in a water landing (as prescribed in paragraphs (c) and (d) of this section), the external doors and windows must be designed to withstand the probable maximum local pressures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Basically, the aircraft needs to have its hydrodynamic behavior while ditching investigated, and it must then float long enough for the occupants to escape. It sounds like the Learjet 60, if ditched, is not guaranteed to either a) remain structurally sound, or b) allow the crew and passengers to get out before it slips below the waves.&lt;/p&gt;&#xA;&lt;p&gt;An aircraft that &lt;em&gt;was&lt;/em&gt; certified for ditching, on the other hand, basically means two things:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The crew knows that they have at least a chance of doing it right (and will possibly change how the aircraft is configured or prepared), probably with an actual published checklist available to them; and:&lt;/li&gt;&#xA;&lt;li&gt;If the crew screws it up, it's &lt;strong&gt;their own fault and the manufacturer might not be held liable&lt;/strong&gt;; the aircraft met certification standards. This would significantly reduce their liability in a crash. It's probably mostly that one, honestly.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-10T23:32:53.913" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="821" PostTypeId="5" CreationDate="2014-01-10T03:56:24.887" Score="0" Body="&lt;p&gt;The AFM contains various sections with information pertaining to the safe operation of the aircraft.  Some typical sections are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limitations&lt;/li&gt;&#xA;&lt;li&gt;Performance&lt;/li&gt;&#xA;&lt;li&gt;Normal Procedures&lt;/li&gt;&#xA;&lt;li&gt;Abnormal Procedures&lt;/li&gt;&#xA;&lt;li&gt;Emergency Procedures&lt;/li&gt;&#xA;&lt;li&gt;Weight &amp;amp; Balance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Questions using this tag should be about the AFM and what it contains or means by a particular statement.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-10T04:24:20.063" LastActivityDate="2014-01-10T04:24:20.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="822" PostTypeId="4" CreationDate="2014-01-10T03:56:24.887" Score="0" Body="An Aircraft Flight Manual is a book containing the information required to operate the aircraft that is published by the manufacturer of the aircraft." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-10T04:24:06.780" LastActivityDate="2014-01-10T04:24:06.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="824" PostTypeId="5" CreationDate="2014-01-10T04:46:36.033" Score="0" Body="&lt;p&gt;Part 25 of the US Federal Air Regulations deals with airworthiness standards for transport category airplanes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains regulatory requirements pertaining to transport category aircraft certification in the USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transport airplanes are airplanes for which a type certificate is applied for under part 21 in the transport category and that meet the transport category airworthiness requirements. Multi-engine airplanes with more than 19 seats or a maximum takeoff weight greater than 19,000 lb must be certificated in the transport category.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;tpl=/ecfrbrowse/Title14/14cfr25_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;The full text of FAR 25 can be found online, as 14 CFR 25&lt;/a&gt;, as well as in printed form at most pilot shops.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-10T05:55:01.523" LastActivityDate="2014-01-10T05:55:01.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="825" PostTypeId="4" CreationDate="2014-01-10T04:46:36.033" Score="0" Body="Part 25 of the US Federal Air Regulations (FARs) is titled &quot;AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES&quot;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-10T05:54:58.163" LastActivityDate="2014-01-10T05:54:58.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="826" PostTypeId="1" AcceptedAnswerId="827" CreationDate="2014-01-10T05:30:02.183" Score="11" ViewCount="2604" Body="&lt;p&gt;Somewhere in the United States, there's an airfield (probably military) with a runway made entirely out of metal.  I've seen the approach plate for it, but I can't remember the identifier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What airfield am I thinking of?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-02-28T03:37:00.440" Title="There's an airfield somewhere in the United States with a metal runway. Where is it?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="827" PostTypeId="2" ParentId="826" CreationDate="2014-01-10T05:43:35.577" Score="17" Body="&lt;p&gt;You are thinking of &lt;a href=&quot;http://skyvector.com/airport/NJM/Bogue-Field-Mcalf-Airport&quot;&gt;Bogue Field (KNJM)&lt;/a&gt;. It is a Marine Corps auxiliary landing field, currently mocked up to look like a carrier deck, and last I heard it was still active and in use to practice carrier landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway surface is Perforated Steel Planking (PSP - actually I believe the new stuff isn't &quot;steel&quot; anymore but the name remains) - discrete sections that can be laid out to quickly construct temporary landing strips in forward combat zones.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A search on AirNav for &quot;pierced steel plaking&quot; came up with a couple more military fields:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airnav.com/airport/KNXP&quot;&gt;KNXP&lt;/a&gt;   Twentynine Palms SELF Airport (Strategic Expeditionary Landing Field) - &#xA;Twentynine Palms, California, USA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airnav.com/airport/2CA9&quot;&gt;2CA9&lt;/a&gt;   Castle Dome Army Heliport - &#xA;Yuma Proving Ground (Yuma), Arizona, USA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2CA9 says it's a helipad but it's 3000x65. The rest of the results were all (reasonably sized) helipads.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-02-28T03:37:00.440" LastActivityDate="2015-02-28T03:37:00.440" CommentCount="2" CommunityOwnedDate="2014-01-10T05:43:35.577" ContentLicense="CC BY-SA 3.0" />
  <row Id="828" PostTypeId="2" ParentId="809" CreationDate="2014-01-10T07:19:00.230" Score="5" Body="&lt;p&gt;Canada has similar procedures to the US.  From the &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-menu-3092.htm&quot;&gt;Transport Canada Aeronautical Information Manual&lt;/a&gt;, in the COM section:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;5.11 Emergency Communications&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The first transmission of the distress call and message by an aircraft&#xA;  should be on the air-to-ground frequency in use at the time. If the&#xA;  aircraft is unable to establish communication on the frequency in use,&#xA;  the distress call and message should be repeated on the HF general&#xA;  calling or distress frequency 3 023.5 kHz, 5 680 kHz, 121.5 MHz, 406.1&#xA;  MHz, or other distress frequency available, such as 2 182 kHz, in an&#xA;  effort to establish communications with any ground station or the&#xA;  maritime service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="487" LastActivityDate="2014-01-10T07:19:00.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="829" PostTypeId="1" AcceptedAnswerId="837" CreationDate="2014-01-10T12:48:31.147" Score="32" ViewCount="8379" Body="&lt;p&gt;It's noted in many POHs to keep your aircraft clean all the time, but is there a reason to this?  Dirt hardly add any sort of weight to the aircraft, bugs are extremely small and other things such as cars easily move even when dirty as a mud pig.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does having dirt or bugs on your aircraft seriously affect the structure or performance signficantly?&lt;br&gt;&#xA;If so, why?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="64" LastEditDate="2014-01-10T15:34:38.220" LastActivityDate="2014-01-12T11:29:30.687" Title="Why are dirt and bugs on an aircraft so bad?" Tags="&lt;aircraft-performance&gt;&lt;aircraft-maintenance&gt;" AnswerCount="9" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="830" PostTypeId="2" ParentId="829" CreationDate="2014-01-10T13:38:03.270" Score="6" Body="&lt;p&gt;The first thought is possibly that a build-up of dirt/bugs on the surfaces of the aircraft would affect the smooth flow of air and thus affect the amount of drag produced. This could, albeit quite slight, affect the flight characteristics of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a secondary thought, certain substances - especially bird poo - are quite corrosive and could therefore lead to more structural damage which is extremely hard to spot. You should keep your car clean for much the same reason - however on a car the worst you're going to get is a little rust spot on your bodywork. In the wrong place on a aircraft that could be a corroded rivet or bolt.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2014-01-10T13:38:03.270" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="831" PostTypeId="2" ParentId="829" CreationDate="2014-01-10T13:43:27.800" Score="28" Body="&lt;p&gt;One of the main reasons why it's not a good thing to have dead bugs on the windshield is that it becomes very difficult to spot other traffic. Other planes are just little specks at a distance and when your windshield is covered with specks from dead bugs it becomes very difficult to spot another aircraft in the distance.&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2014-01-10T13:43:27.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="832" PostTypeId="2" ParentId="829" CreationDate="2014-01-10T13:48:20.453" Score="17" Body="&lt;p&gt;Bugs or other dirt can have several effects on a (light) aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It will have some effect on airflow, however slight&lt;/li&gt;&#xA;&lt;li&gt;It may affect the paint or surface by corroding or leaving stains&lt;/li&gt;&#xA;&lt;li&gt;It can block pitot tubes or other openings&lt;/li&gt;&#xA;&lt;li&gt;It can build up on windows and obstruct the view&lt;/li&gt;&#xA;&lt;li&gt;A heavy buildup of dirt could make the brakes less effective&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The effect of dead bugs on airflow is probably negligible (frost or ice would be a different story), but a blocked pitot tube can be very dangerous because the airspeed indicator will read incorrectly. Dead bugs on the windscreen may seem like a minor issue, but even a small blind spot could hide another aircraft and prevent the pilot seeing it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-10T13:48:20.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="833" PostTypeId="1" AcceptedAnswerId="836" CreationDate="2014-01-10T14:34:22.323" Score="30" ViewCount="7498" Body="&lt;p&gt;I have heard it is very difficult for a pilot to land on a carrier deck.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;a href=&quot;https://aviation.stackexchange.com/questions/475/aircraft-carrier-landing&quot;&gt;have read this question&lt;/a&gt; but it didn't really give me a sense of the challenges that pilots face.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/827/57&quot;&gt;This question lent me the insight&lt;/a&gt; that &lt;strong&gt;&lt;em&gt;metal decks&lt;/em&gt;&lt;/strong&gt;, themselves, have different properties (that I should have considered)... perhaps friction, changes due to thermal shifts (that asphalt does not exhibit), perhaps it 'gives' differently under touch-down pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone paint a more-complete picture?  I'm sure there are also other factors, besides that the deck is moving.... but even then - perhaps there are 'different kinds' of movements of the deck that I haven't considered.&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2019-01-11T02:14:53.440" Title="What makes it so hard to land on an aircraft carrier?" Tags="&lt;landing&gt;&lt;aircraft-carrier&gt;" AnswerCount="5" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="834" PostTypeId="5" CreationDate="2014-01-10T14:35:26.780" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-10T14:35:26.780" LastActivityDate="2014-01-10T14:35:26.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="835" PostTypeId="4" CreationDate="2014-01-10T14:35:26.780" Score="0" Body="Anything related to the operation of aircraft around carriers: landing, take-off, taxi, storage, etc." OwnerUserId="57" LastEditorUserId="57" LastEditDate="2014-01-10T15:04:17.313" LastActivityDate="2014-01-10T15:04:17.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="836" PostTypeId="2" ParentId="833" CreationDate="2014-01-10T14:46:58.247" Score="27" Body="&lt;h1&gt;Edit&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Since another user, with actual carrier experience, has given a &lt;a href=&quot;https://aviation.stackexchange.com/a/58938/43&quot;&gt;detailed answer&lt;/a&gt;, please refer to his answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It now appears that a good part of my answer was incorrect.  As I wrote in the beginning, my answer was based on flight-sim experience, and reading, but nothing formal or official.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll leave my answer up, solely for historical reference, unless the better answer gets accepted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&lt;hr&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never done it IRL, but read about it lots, and Flight Simmed it many times, so I'll take a stab.&lt;br&gt;(&lt;em&gt;until someone who has actually done it says better&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Glide Path&lt;/strong&gt;&lt;br&gt;&#xA;When landing on a fixed runway, your glide-path is pretty much right towards the end of the runway.&lt;br&gt;Its not like that at all on a Carrier.  From up high, you are actually aiming for a point &lt;em&gt;in front&lt;/em&gt; of the carrier.  You're aiming for where the runway &lt;em&gt;will be&lt;/em&gt; in 30 seconds.   As you get closer, the carrier moves closer into position.  But still not entirely in position until the last second.   So you're always aiming for an invisible/imaginary point where the runway will be at the last second.&#xA;&lt;p&gt;This is the best picture I've found of what I'm describing:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/tf6tN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tf6tNm.jpg&quot; alt=&quot;Carrier landing&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Notice that the flight path indicator (the little circle in the HUD) is well beyond the front of the carrier.  If this plane was landing on a runway, the flight path would be aimed right at the numbers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;No Flare&lt;/strong&gt;&lt;br&gt;&#xA;In a typical runway landing you flare out just before touchdown, &quot;float&quot; for a second and drop on to the runway.&lt;br&gt;In a carrier landing, you maintain your glide-path attitude all the way on to the deck.   There's no flare or float. This helps you hit exactly the spot you're aiming for (the 3-wire), but in some sense you really are crashing into the deck at a not-inconsiderable descent rate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Pitching Deck&lt;/strong&gt;&lt;br&gt;&#xA;Remember the glide path to the imaginary touch-down point?  Because the carrier deck can be pitching or rolling in the waves, that imaginary touch-down point is not a fixed distance directly in front of the ship.  As the ship bobs and weaves around, your touchdown point is moving around too.   That makes it even harder to hit the point right.  It can well be at the last second, as your plane is dropping quickly, the deck suddenly jumps up to meet you, making the impact even more violent.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Sideways Movement&lt;/strong&gt;&lt;br&gt;&#xA;The landing part of a carrier deck is the diagonal part on the back of the deck.   It is angled about 20-degrees to the left, relative to the carrier.  But it is moving directly forward with the movement of the carrier.  This means the &quot;runway&quot; is not moving directly away from you, but slipping sideways.   &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2019-01-11T02:14:53.440" LastActivityDate="2019-01-11T02:14:53.440" CommentCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="837" PostTypeId="2" ParentId="829" CreationDate="2014-01-10T14:54:33.417" Score="36" Body="&lt;p&gt;For (modern) gliders with highly optimized laminar flow &lt;a href=&quot;https://en.wikipedia.org/wiki/Airfoil&quot; rel=&quot;noreferrer&quot;&gt;airfoils&lt;/a&gt;, bugs (or dirt) are a non-negligible factor, especially in competition gliding. There are some older laminar airfoils that are notoriously allergic to bugs (and rain), but all are to a certain degree. This is also the reason why any glider pilot worth his or her salt will painstakingly clean their ship each afternoon and before each competition flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sufficient bugs will degrade your performance by a noticeable amount - most gliding computers even have a special &quot;bug&quot; factor to include that into glide path calculation (even though the measuring and correllation of that is quite subjective). I´ve had a few flights in somewhat biblically bug-infested conditions (summer, hot, low thermals) that more or less painted the leading edge black (like in this picture from an &lt;a href=&quot;http://www.dg-flugzeugbau.de/mueckenputzer-e.html&quot; rel=&quot;noreferrer&quot;&gt;article on the DG Flugzeugbau website&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AilMW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bug wipers are quite common on high-end and competition gliders and can be found e.g. at &lt;a href=&quot;http://www.storka.at/&quot; rel=&quot;noreferrer&quot;&gt;http://www.storka.at/&lt;/a&gt;. Or try to google for &quot;Mückenputzer&quot;. Of course bug wipers are not without drawbacks (concerning cost, installation, ease of use, drag etc.). A friend of mine once stuck a banana peel on his wing and tried to remove that with the wiper, resulting in banana &lt;em&gt;and&lt;/em&gt; wiper being stuck in the middle of the wing. It took some creative maneuvers to clear &lt;em&gt;that&lt;/em&gt; mess, by which time probably a lifetime aerodynamic benefit of cleaning had been spent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the comparison with cars, their &lt;a href=&quot;https://en.wikipedia.org/wiki/Automotive_aerodynamics&quot; rel=&quot;noreferrer&quot;&gt;aerodynamics&lt;/a&gt; differ in a lot of ways. In comparison to a wing there is no laminar flow to talk of at higher speeds (most of it is turbulent), which drastically reduces the influence of the surface smoothness on the drag produced.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2014-01-10T15:51:48.337" LastActivityDate="2014-01-10T15:51:48.337" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="838" PostTypeId="1" AcceptedAnswerId="840" CreationDate="2014-01-10T15:11:33.077" Score="35" ViewCount="47814" Body="&lt;p&gt;I recently came across this picture of the Boeing 787 series aircraft's incredible wingflex:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lEhvU.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose this is a consequence of using very light CFRP wings, but how does the wingflex itself improve the 787's flight performance? Do the benefits/drawbacks also apply to the 747-8 (which IIRC also uses CFRP wings)?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="14897" LastEditDate="2020-03-05T09:48:20.307" LastActivityDate="2020-03-05T09:48:20.307" Title="What are the effects of the Boeing 787's very flexible wings?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;boeing-787&gt;&lt;wing-flex&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="839" PostTypeId="2" ParentId="738" CreationDate="2014-01-10T16:37:36.377" Score="12" Body="&lt;p&gt;Since I was a young kid I was addicted to flight sims. In all honesty, I think that is what really developed my passion for flying - I'm now 18 with a PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I found with MS:FS is that it really helped me in terms of understanding things. For example, how control input = output, how VOR works, and good airmanship. This led me to be 8 lessons &lt;em&gt;ahead&lt;/em&gt; of where I should be, when I was 8 lessons in. - What would happen is that I'd go up with my instructor, and the planned lesson would be completed [well] within a few minutes, so they started the next lesson in the air.. 8 times in a row. I give this credit to flight simulator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After what I like to call the &quot;practical part&quot; of flying, IE learning how to make the aircraft do as you want, MS:FS stops having a real effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot properly learn to navigate, talk to ATC, taxi, do checks etc with a flight simulator. And, if you do it properly, you won't find any downsides with learning with one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A common issue is that people may become obsessed with the instruments in a cockpit, and not look &lt;em&gt;outside&lt;/em&gt;. Try and stay conscious of how much you use instruments, and I strongly suggest getting a peripheral such as TrackIR, which simulates head movement (best £100 I've ever spent). There are also online groups such as VATSIM which provide advanced tutoring to fly like a professional, with copilots and talking to voluntary certified ATCOs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a more realistic flight dynamics experience, I recommend Xplane 10, if your computer can handle it. I have some videos on my &lt;a href=&quot;http://www.youtube.com/user/FlightInformer/videos&quot;&gt;YouTube channel&lt;/a&gt; that show how sims can be useful for some things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Happy flying :)&lt;/p&gt;&#xA;" OwnerUserId="369" LastActivityDate="2014-01-10T16:37:36.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="840" PostTypeId="2" ParentId="838" CreationDate="2014-01-10T16:40:46.000" Score="25" Body="&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/267122/&quot; rel=&quot;noreferrer&quot;&gt;From here:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The amount of flex is really a product of the material. The wing requires a specified ultimate strength; with metal, that translates into a given amount of flex. This can be varied within limits, but it is really the material, its stiffness to yield point ratio, and its fatigue properties, that control how much flex you are going to end up with. CFRP is a very different material, and has much less stiffness for the same yield point, and has essentially no fatigue problems. This is beneficial in that it provides a smoother ride in turbulence; the wing acting essentially like a giant leaf spring. There is some lift lost due to the nature of the curvature, though. However, this is relatively small.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="369" LastEditorUserId="1696" LastEditDate="2015-09-08T02:44:23.003" LastActivityDate="2015-09-08T02:44:23.003" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="841" PostTypeId="2" ParentId="200" CreationDate="2014-01-10T16:42:39.977" Score="1" Body="&lt;p&gt;Polishing the frost until smooth used to be a legally permitted way of handling the problem.  The regs have changed, because a very small amount of frost, polished or not, can seriously affect your aircraft's performance.  It must be removed!  POLISHING THE FROST IS NO LONGER PERMITTED.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if the frost is not on control surfaces, say on the top of the fuselage, it is ok to fly with it on.  (Unless of course you are flying a Piaggio or some other plane where the shape of the fuselage creates lift...)  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-10T16:42:39.977" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="844" PostTypeId="2" ParentId="786" CreationDate="2014-01-10T17:13:03.453" Score="2" Body="&lt;p&gt;It is not only remotely feasible it is very possible. One of our club members departed a sea-level airport and reached 6,500 feet altituce when the engine quit.  He turned back and landed on the runway he departed from.  He actually landed long and over-ran the runway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now try that at 500 feet above runway altitude and you won't be able to make it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So where you are when the fan stops is important, as is your skill level.  Get with a CFI and practice this! &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-10T17:13:03.453" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="845" PostTypeId="5" CreationDate="2014-01-10T17:16:08.887" Score="0" Body="&lt;p&gt;Safety is a very broad topic and includes all measures taken to protect aircraft, passengers and crew from accidents or other incidents. Safety can be achieved and improved in many different ways including aircraft design, airspace layout, crew training, maintenance, flight planning, post-incident investigations and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that safety should not be confused with security, which is concerned with protection against deliberate malicious acts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about how aviation safety is measured, achieved and improved, including questions about accidents and accident investigation. For questions that are purely about security (e.g. anti-hijacking measures) use &lt;a href=&quot;/questions/tagged/security&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'security'&quot; rel=&quot;tag&quot;&gt;security&lt;/a&gt; instead, although some questions may involve both safety and security.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_safety&quot; rel=&quot;nofollow&quot;&gt;Aviation safety&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faasafety.gov/&quot; rel=&quot;nofollow&quot;&gt;FAA Safety Team&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-18T17:29:56.327" LastActivityDate="2015-01-18T17:29:56.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="846" PostTypeId="4" CreationDate="2014-01-10T17:16:08.887" Score="0" Body="Safety includes all aspects of protecting aircraft, passengers and crew from accidents, mistakes and other potentially dangerous situations." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-18T17:29:56.327" LastActivityDate="2015-01-18T17:29:56.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="847" PostTypeId="1" CreationDate="2014-01-10T17:24:55.977" Score="15" ViewCount="17629" Body="&lt;p&gt;Are there any LSA aircraft that are IFR certified? A LSA would be the perfect private commuter plane for an instrument rated private pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, what are the most cost effective airplanes that are IFR certified? Is there anything cheaper than a C172?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to be clear: I am asking about aircraft that are IFR &lt;em&gt;certified&lt;/em&gt;, meaning that they can be flown IFR in IMC conditions. I am also aware that there is a huge difference between different countries with regard to aircraft certification so my question is mainly about the U.S.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="72" LastEditDate="2014-03-03T05:33:46.753" LastActivityDate="2020-05-30T12:41:03.687" Title="Are there any LSA aircraft that can be flown IFR in IMC?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;aircraft-certification&gt;&lt;light-sport-aircraft&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="848" PostTypeId="2" ParentId="847" CreationDate="2014-01-10T17:42:28.510" Score="5" Body="&lt;p&gt;A quick websearch leads me to believe that you can fly a properly equipped LSA on an IFR flight plan (eg: being directed by ATC), but you &lt;em&gt;cannot&lt;/em&gt; fly an LSA into IMC.&lt;p&gt;IMC and IFR are not the same thing, and LSA's may be equipped for IFR flight, but they cannot be certified for IMC flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sources:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.flyingmag.com/aircraft/lsasport/lsa-instrument-training&quot; rel=&quot;nofollow noreferrer&quot;&gt;LSA for Instrument Training?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Frequently-Asked-Questions-About-Sport-Pilot.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Light Sport Aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;More info, April, 2017:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://generalaviationnews.com/2017/04/17/can-you-fly-ifr-in-an-lsa/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://generalaviationnews.com/2017/04/17/can-you-fly-ifr-in-an-lsa/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In summary, if you are an instrument pilot, and if you are current, and if you have a medical, and if you purchase an aircraft like the Bristell and register it as an ELSA, no regulation prevents you from filing and flying IFR including into IMC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2017-04-25T16:58:32.593" LastActivityDate="2017-04-25T16:58:32.593" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="849" PostTypeId="2" ParentId="847" CreationDate="2014-01-10T17:44:31.793" Score="5" Body="&lt;p&gt;There is at least one LSA that is approved for IFR flight: &lt;a href=&quot;http://www.zenithair.com/zodiac/ch650/index.html&quot; rel=&quot;nofollow&quot;&gt;The Zodiac 650&lt;/a&gt; (available as a kit, or a factory-built Special Light Sport Aircraft).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;More broadly, you can operate light sport aircraft under IFR (in VMC or IMC) as long as it's permitted by the operating instructions. &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Frequently-Asked-Questions-About-Sport-Pilot.aspx&quot; rel=&quot;nofollow&quot;&gt;AOPA's Light Sport / Sport Pilot FAQ&lt;/a&gt; addresses this well, so I'll just steal their answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Can I fly a special light sport aircraft (SLSA) in IFR conditions or at night?&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Only day/VFR conditions are specifically addressed in the ASTM consensus standards that govern the production of SLSA. Being that sport pilots and those exercising sport pilot privileges are limited to flying only in day/VFR conditions, this seems appropriate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;On the other hand, if an appropriately rated pilot (example: private pilot with an instrument rating) wants to fly SLSA under IFR or at night, the aircraft's operating limitations must allow it, and the aircraft must be equipped per 91.205 for VFR flight at night and/or IFR flight. Additionally, 91.327(d) requires all SLSA to be operated in accordance with the aircraft's operating instructions. Operating instructions differ from operating limitations in that the engine, airframe, and accessory manufacturers issue them; the FAA issues operating limitations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An example of operating instructions is a SLSA equipped with a Rotax engine. Rotax's operating instructions prohibit the use of a Rotax engine at night or in IFR conditions unless it is the FAA type certificated engine (14 CFR part 33). Other engine, airframe, and accessory manufacturers might impose similar restrictions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If you are appropriately rated and would like to operate a special light sport aircraft at night or under IFR, contact the manufacturer to determine if any provisions can be made.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Note also that there were some rumors of the ASTM consensus standards changing at some point to require &lt;code&gt;DAY VFR ONLY&lt;/code&gt; placards on new Special Light-Sport Aircraft -- At this time I don't believe that's happened yet, but it might...)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-10T18:01:10.907" LastActivityDate="2014-01-10T18:01:10.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="850" PostTypeId="2" ParentId="847" CreationDate="2014-01-10T17:45:03.027" Score="5" Body="&lt;p&gt;Yes. As long as the pilot is IFR rated with a medical certificate and the aircraft is properly equipped. Including IFR certified lighting, avionics and power-plant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ASTM commitee voted to ban LSA flight into IMC, but that has not been approved by the FAA, as mentioned &lt;a href=&quot;http://light-sport-hangar-flyin.blogspot.com/2010/08/weve-all-seen-ads-full-ifr-equipped-lsa.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="65" LastEditDate="2015-03-04T18:32:30.400" LastActivityDate="2015-03-04T18:32:30.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="851" PostTypeId="5" CreationDate="2014-01-10T18:13:55.087" Score="0" Body="&lt;p&gt;Weather refers to atmospheric conditions such as &lt;a href=&quot;/questions/tagged/wind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wind&amp;#39;&quot; rel=&quot;tag&quot;&gt;wind&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/temperature&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;temperature&amp;#39;&quot; rel=&quot;tag&quot;&gt;temperature&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/precipitation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;precipitation&amp;#39;&quot; rel=&quot;tag&quot;&gt;precipitation&lt;/a&gt;, all of which have a large influence over aviation activities, especially flights. Weather is a key factor in &lt;a href=&quot;/questions/tagged/flight-planning&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-planning&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-planning&lt;/a&gt;, but also affects &lt;a href=&quot;/questions/tagged/aircraft-design&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-design&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-design&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/equipment&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;equipment&amp;#39;&quot; rel=&quot;tag&quot;&gt;equipment&lt;/a&gt;, and is always included in &lt;a href=&quot;/questions/tagged/flight-training&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-training&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-training&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;National weather services usually prepare aviation-specific forecasts and other information, and there are international formats for describing weather in aviation terms. Among the most well known are &lt;a href=&quot;/questions/tagged/metar&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;metar&amp;#39;&quot; rel=&quot;tag&quot;&gt;metar&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/taf&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;taf&amp;#39;&quot; rel=&quot;tag&quot;&gt;taf&lt;/a&gt;s, which are current observations and forecasts for a specific &lt;a href=&quot;/questions/tagged/airport&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airport&amp;#39;&quot; rel=&quot;tag&quot;&gt;airport&lt;/a&gt; or weather observation point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for all questions where weather is a factor, including weather observation and forecasting (for aviation specifically), the effect of weather on aircraft and flight planning, in-flight operational considerations, etc..&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Weather&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weather&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://aviationweather.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Weather Center&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_aerodrome_forecast&quot; rel=&quot;nofollow noreferrer&quot;&gt;TAF&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-13T07:36:03.790" LastActivityDate="2019-10-13T07:36:03.790" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="852" PostTypeId="4" CreationDate="2014-01-10T18:13:55.087" Score="0" Body="Weather means the atmospheric conditions, including wind, temperature and precipitation, in a specific area at a specific time." OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-13T09:27:18.427" LastActivityDate="2019-10-13T09:27:18.427" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="853" PostTypeId="1" CreationDate="2014-01-10T18:32:11.083" Score="6" ViewCount="2392" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/74438&quot; rel=&quot;nofollow&quot;&gt;Advisory Circular AC 61-136&lt;/a&gt; which outlines the approval and limitations of flight training devices seems to contradict &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.57(c)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To what extent can I use an AATD for instrument currency? In addition, to what extent can an AATD be used toward and instrument proficiency check (IPC)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have located this &lt;a href=&quot;http://www.kingschools.com/flight-simulators/redbird/docs/approved-instrument-recency-experience-without-a-flight-instructor.pdf&quot; rel=&quot;nofollow&quot;&gt;document&lt;/a&gt; from the FAA Office of Aviation Safety that clarifies that AATDs and BATDs are governed by &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.4&quot; rel=&quot;nofollow&quot;&gt;FAR 61.4(c)&lt;/a&gt; and are authorized for specific purposes and can be used in the same manner at a Flight Training Device instead of a Aviation Training Device as long as they have an approve Letter of Agreement (LOA) from the administrator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This leads me to believe that an AATD qualifies for FAR &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot; rel=&quot;nofollow&quot;&gt;61.57(c)(2)&lt;/a&gt; not FAR &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot; rel=&quot;nofollow&quot;&gt;61.57(c)(3)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="72" LastEditDate="2014-03-03T05:31:55.420" LastActivityDate="2017-04-11T01:10:09.523" Title="Can I log instrument flight time for currency purposes in an Advanced Aviation Training Device (AATD)?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="854" PostTypeId="2" ParentId="853" CreationDate="2014-01-10T19:03:22.397" Score="3" Body="&lt;p&gt;From what I can tell, the Advisory Circular is outdated. It was issued July 14, 2008, while the most recent update to 14 CFR 61.57 was effective Nov 15, 2013.&lt;/p&gt;&#xA;&lt;p&gt;When the AC was issued, 61.57(c) &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/253B8561B407368686256DAC004DA961?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;did not contain the wording specific to Aviation Training Devices&lt;/a&gt; (effective 11/17/2003). That language was added in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/246A05C63B4083B48625768F005D0F75?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;the version effective 10/20/2009&lt;/a&gt;, and the AC apparently has not been revised since that point.&lt;/p&gt;&#xA;&lt;p&gt;At this point the regulations are more specific (and regulatory) than the Advisory Circular. You should be able to log recent flight instrument experience in a ATD based on 61.57(c)(3), or the subsequent subsections that pertain to mixed currency.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(3) Use of an aviation training device for maintaining instrument experience. Within the 2 calendar months preceding the month of the flight, that person performed and logged at &lt;strong&gt;least the following tasks, iterations, and time&lt;/strong&gt; [&lt;em&gt;emphasis mine&lt;/em&gt;] in an aviation training device and has performed the following--&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(i) Three hours of instrument experience.&lt;br/&gt;&#xA;(ii) Holding procedures and tasks.&lt;br/&gt;&#xA;(iii) Six instrument approaches.&lt;br/&gt;&#xA;(iv) Two unusual attitude recoveries while in a descending, Vne airspeed condition and two unusual attitude recoveries while in an ascending, stall speed condition.&lt;br/&gt;&#xA;(v) Interception and tracking courses through the use of navigational electronic systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-10T20:21:50.650" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="855" PostTypeId="5" CreationDate="2014-01-10T19:11:30.737" Score="0" Body="&lt;p&gt;An aircraft propeller is a set of airfoils (most propellers have from two to six of these airfoils, which are called &lt;em&gt;propeller blades&lt;/em&gt;) designed to convert the rotary motion of a spinning engine shaft (usually from a &lt;a href=&quot;/questions/tagged/piston-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;piston-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;piston-engine&lt;/a&gt; or &lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt;) into thrust which can be used to propel an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All early aircraft used propellers for propulsion; small &lt;a href=&quot;/questions/tagged/general-aviation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;general-aviation&amp;#39;&quot; rel=&quot;tag&quot;&gt;general-aviation&lt;/a&gt; aircraft and many commuter and regional airliners still use propellers, as do many midsize cargo aircraft and military transports, but they have been superseded by various types of &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt; for essentially all combat aircraft and large airliners and cargo planes designed since the 1950s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft propellers are generally made of metal, wood, or composite materials, and may be fixed-pitch, ground-adjustable, or constant-speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional information can be found in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Propeller_(aircraft)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article on aircraft propellers&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2018-12-29T09:41:17.867" LastActivityDate="2018-12-29T09:41:17.867" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="856" PostTypeId="4" CreationDate="2014-01-10T19:11:30.737" Score="0" Body="Aircraft propellers are airfoils which convert rotary motion from a piston or turbine engine into thrust suitable for propelling an aircraft." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-10T19:31:40.680" LastActivityDate="2014-01-10T19:31:40.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="857" PostTypeId="2" ParentId="786" CreationDate="2014-01-10T19:51:28.247" Score="17" Body="&lt;p&gt;Nobody mentioned the theory so far, so I'll try to fill in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Disclaimer: The below calculations and estimates are based on what I know about the physics involved. I don't know whether they are actually mentioned in pilot operating handbook of any aircraft.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To successfully turn back, you after climbing at best climb rate, when the engine quits you push down, execute the turn at suitably slightly higher speed to maintain the angle of attack and glide back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rate of climb is thrust/weight minus lift/drag, the glide rate is just lift/drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glide rate in the turn is higher by factor depending on the bank angle (coordinated turn; uncoordinated turn is always worse). Calculating best glide rate turn leads to bank angle should be around 45°, speed should be about 19% higher to maintain best glide angle of attack and about 41% higher rate of descent than in straight glide. According to the article linked in the other answer, flying at just above stall speed (which is also 19% higher than in straight flight) should be better due to tighter circle despite worse lift/drag ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radius, and thus length of the turn of course depends on speed. At 110 knots (true speed, not indicated) the turn will take about 1.4 nm, at 160 knots it will already be about 3 nm. At 60 knots it will only be 0.42 nm. Since you need to maintain indicated speed, the true speed will slightly increase with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So for the turn back to be possible the plane needs to have sufficient power to climb faster than it will descend in the glide and you have to be high enough to allow for the extra gliding distance (which due to higher rate of descent corresponds to even longer straight glide).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All or most planes will have sufficient thrust at sea level to climb faster than they descend in glide. But since thrust decreases with altitude and temperature, if your departure point is high or warm enough, it may no longer be the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the thrust is sufficient, the distance between climb and glide profile starts at zero on lift-off and will only become sufficient to cover the extra miles in the turn above some altitude. The altitude depends on many factors mentioned above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not reasonable to try it without knowing what altitude is needed for it at current conditions.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-01-11T00:08:30.467" LastActivityDate="2014-01-11T00:08:30.467" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="858" PostTypeId="5" CreationDate="2014-01-10T20:53:40.557" Score="0" Body="&lt;p&gt;VOR (VHF Omnidirectional Range) is a radio navigation technology used by aircraft to determine their position and remain on-course.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article on VORs&lt;/a&gt; contains some of the technical details on how the radio signal actually works, but a very simple conceptual explanation of how a VOR works can be found &lt;a href=&quot;http://stoenworks.com/Tutorials/Understanding%20Vors.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, and is paraphrased below:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At its core a VOR station emits two signals - a &quot;sweep&quot; and a &quot;strobe&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The sweep signal continually rotates through a 360 degree circle at a known rate.  &lt;/li&gt;&#xA;  &lt;li&gt;Every time the sweep signal crosses 0 degrees (North) the strobe signal fires.  &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;By timing the difference between when you receive the &quot;strobe&quot; signal and when the &quot;sweep&quot; signal arrives you can determine your bearing to the station, as shown in the animation below.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4n430.gif&quot; alt=&quot;VOR animation&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For an interactive demonstration of how VOR signals correspond to the navigational instruments in an aircraft &lt;a href=&quot;http://www.myaviationschool.com/free-aviation-products/simulators/vor-simulator.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;check out this VOR simulator&lt;/a&gt; (requires Flash).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-10T21:03:30.043" LastActivityDate="2014-01-10T21:03:30.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="859" PostTypeId="4" CreationDate="2014-01-10T20:53:40.557" Score="0" Body="VOR (VHF Omnidirectional Range) is a radio navigation technology used by aircraft to determine their position and remain on-course." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-10T21:03:34.090" LastActivityDate="2014-01-10T21:03:34.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="860" PostTypeId="2" ParentId="426" CreationDate="2014-01-10T21:25:14.230" Score="15" Body="&lt;p&gt;Both of the Boeing 747 operators I flew for in the 1990s observed a max taxi speed of 25 knots on a straight taxiway. We were told in ground school that Boeing recommended 20 knots.&lt;/p&gt;&#xA;&lt;p&gt;Concerning a previous answer of 10 knots in a turn, while that may be a good general answer, it would be subject to conditions. I remember once almost leaving the taxiway in a turn at Jeddah even though I was a little less than 10 knots. It was over 110F, which made the asphalt a little slippery. After than experience, I slowed my 90 degree turns to around 6-7 knots if there was any question concerning the conditions.&lt;/p&gt;&#xA;&lt;p&gt;Another consideration concerning taxi speed is how heavy you are and how far you have to taxi. The problem is tire heating. I seem to remember being told the Boeing 747 had a maximum taxi distance of 30,000 feet at maximum weight. I don't know whether that was really true, but I do know that at Honolulu a taxi to the reef runway from some parking areas is at or a little over that.&lt;/p&gt;&#xA;&lt;p&gt;Since I've been retired for 15 years, please take anything I say with due consideration to my ageing-failing brain.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="9702" LastEditDate="2020-11-05T09:56:38.397" LastActivityDate="2020-11-05T09:56:38.397" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="861" PostTypeId="2" ParentId="738" CreationDate="2014-01-10T21:28:43.077" Score="15" Body="&lt;p&gt;I'm not a pilot so I can't answer the second part of the question, but &lt;strong&gt;a flight sim can definitely help with learning.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My story:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been &quot;playing with&quot; MS Flight Simulator ever since the first version came out for the original Mac's nine-inch black-and-white monitor. (It only had the Cessna 172, a Learjet, and a Sopwith Camel.) Many years later, while working at Microsoft, I was practically the only person in the office (not USA) able to do the product press demo at the launch of MS Flight Sim 97 &lt;em&gt;(edit: it was more likely &lt;a href=&quot;https://en.wikipedia.org/wiki/History_of_Microsoft_Flight_Simulator#Flight_Simulator_2000&quot; rel=&quot;noreferrer&quot;&gt;FS2000&lt;/a&gt;, a major upgrade in 1999)&lt;/em&gt;. The Cessna is still in there. After the press conference (at an airport!), people were invited to try it for real; we had hired a couple of flight instructors and their ... Cessna's! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was lucky to get the final slot, and I swear that &lt;em&gt;the only thing the flight instructor ever touched was the radio, and the prop angle at take-off!&lt;/em&gt; I had never touched an airplane before (except as an airline passenger, duh) but with my MSFS practice -- even without yoke and pedals -- I just felt right at home and every detail of the 10-minute flight was just as I expected it to be. My own impression is that my flight and landing was considerably smoother than the other &quot;student&quot; that I flew with.&lt;/p&gt;&#xA;" OwnerUserId="536" LastEditorUserId="536" LastEditDate="2015-09-03T20:59:24.287" LastActivityDate="2015-09-03T20:59:24.287" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="862" PostTypeId="2" ParentId="829" CreationDate="2014-01-10T21:42:14.863" Score="8" Body="&lt;p&gt;A lot of bugs on the leading edge of a wing does significantly degrade performance. Years ago I gave a lot of float plane instruction in a J3 with an 85 hp engine. If the student was heavy and there were a lot of bugs, it wouldn't fly. Clean off the bugs and it would. &lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-01-10T21:42:14.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="863" PostTypeId="5" CreationDate="2014-01-10T21:42:52.777" Score="0" Body="&lt;p&gt;Navigation is the process of traveling from one location to another in a planned, controlled way. This includes planning a route, steering an aircraft (or other vehicle) along it, and checking progress and position against the plan. It also includes other tasks such as determining current position after becoming disoriented. Navigation is a key piloting skill included in all levels of flight training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many techniques and technologies for navigation, but in modern aviation they fall into three main groups:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Visual navigation&lt;/li&gt;&#xA;&lt;li&gt;Ground-based &lt;a href=&quot;/questions/tagged/radio-navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radio-navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;radio-navigation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Satellite (GPS) navigation (also known as &lt;a href=&quot;/questions/tagged/gnss&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gnss&amp;#39;&quot; rel=&quot;tag&quot;&gt;gnss&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Pilots can navigate visually by comparing their view of the ground to a map or aviation chart, looking at landmarks and geographical features to follow their route (also known as &lt;em&gt;pilotage&lt;/em&gt;). This is often done together with &lt;a href=&quot;http://en.wikipedia.org/wiki/Dead_reckoning#Air_navigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;dead reckoning&lt;/a&gt;, where the pilot pre-calculates the necessary headings, distances and times to fly. (&lt;a href=&quot;https://en.wikipedia.org/wiki/Celestial_navigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Celestial navigation&lt;/a&gt; is another, now almost entirely obsolete, form of visual navigation.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots can use ground-based radio aids together with instruments in the aircraft to indicate position and distance in various ways. This includes &lt;a href=&quot;/questions/tagged/vor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vor&amp;#39;&quot; rel=&quot;tag&quot;&gt;vor&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/dme&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dme&amp;#39;&quot; rel=&quot;tag&quot;&gt;dme&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/ndb&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ndb&amp;#39;&quot; rel=&quot;tag&quot;&gt;ndb&lt;/a&gt;, as well as &lt;a href=&quot;/questions/tagged/ils&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ils&amp;#39;&quot; rel=&quot;tag&quot;&gt;ils&lt;/a&gt; transmitters (consisting of separate &lt;a href=&quot;/questions/tagged/localizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;localizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;localizer&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/glideslope&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glideslope&amp;#39;&quot; rel=&quot;tag&quot;&gt;glideslope&lt;/a&gt; transmitters) for final approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS navigation uses satellites, sometimes supported by ground-based transmitters, to show the aircraft's precise position. Conceptually this is very similar to using a 'moving map' GPS system in a car, but aviation GPS units have many additional features including support for flying instrument approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about air navigation.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_navigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air navigation&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://wiki.flightgear.org/Radio_beacons&quot; rel=&quot;nofollow noreferrer&quot;&gt;Radio beacons&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-08-20T10:03:10.633" LastActivityDate="2019-08-20T10:03:10.633" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="864" PostTypeId="4" CreationDate="2014-01-10T21:42:52.777" Score="0" Body="Navigation is the process of planning and controlling travel from one location to another. There are many methods of navigation using different techniques and instruments." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-07-23T15:36:11.937" LastActivityDate="2015-07-23T15:36:11.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="866" PostTypeId="5" CreationDate="2014-01-10T22:00:07.113" Score="0" Body="&lt;p&gt;Passengers (or &lt;em&gt;pax&lt;/em&gt;) on aircraft are people who are not part of the crew and have no tasks or duties on board. A passenger may be a friend on board for a pleasure flight, a paying customer on an airline or other commercial flight, or even an off-duty pilot or &lt;a href=&quot;/questions/tagged/flight-attendant&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-attendant&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-attendant&lt;/a&gt; commuting to their home base (a practice known as &lt;em&gt;deadheading&lt;/em&gt;). Passengers may give the &lt;a href=&quot;/questions/tagged/pilots&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pilots&amp;#39;&quot; rel=&quot;tag&quot;&gt;pilots&lt;/a&gt; directions, and even participate in flight planning (as in the case of charter flights or corporate jets), but they have no legal authority to make decisions in the air, and typically play no part in carrying out the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is appropriate for all questions about the operational and technical aspects of carrying passengers on board any aircraft, and may also be used for aviation questions asked from a passenger's perspective where a reasonably non-technical answer is preferred.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More general questions about passengers on airline flights in particular may be directed to &lt;a href=&quot;http://travel.stackexchange.com/&quot;&gt;travel.stackexchange.com&lt;/a&gt;, especially if the questions are about non-technical business practices such as ticket pricing or overbooking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, &lt;a href=&quot;http://en.wikipedia.org/wiki/Passenger&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-21T06:37:47.750" LastActivityDate="2019-10-21T06:37:47.750" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="867" PostTypeId="4" CreationDate="2014-01-10T22:00:07.113" Score="0" Body="A passenger is someone carried on an aircraft who is not part of the crew and has no responsibility for carrying out the flight." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-10T23:39:10.833" LastActivityDate="2014-01-10T23:39:10.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="868" PostTypeId="2" ParentId="254" CreationDate="2014-01-10T22:07:30.557" Score="8" Body="&lt;p&gt;A EFB is a legal replacement for paper charts and you are not required to carry backup if you are operating as part 91 single engine piston. &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1020099&quot;&gt;Advisory Circular 120-76B&lt;/a&gt; is in reference to part 91F (Large and Turbine-Powered Multiengine Airplanes). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/eb15b0c685650a0486257321006b3b8c/%24FILE/AC%2091_78.pdf&quot;&gt;AC 91-78&lt;/a&gt; is aimed at Part 91 operators, VFR or IFR and states that EFBs can be used in all phases of flight in lieu of paper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A backup data source is suggested, but is not required. Note that this backup can be another electronic device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://ipadpilotnews.com/2013/09/ipad-legal-briefing-for-pilots/&quot;&gt;iPad Legal Briefing for Pilots&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="423" LastEditDate="2014-01-10T22:13:13.320" LastActivityDate="2014-01-10T22:13:13.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="869" PostTypeId="2" ParentId="786" CreationDate="2014-01-10T22:08:57.150" Score="5" Body="&lt;p&gt;Interesting question, especially as I'm learning to fly just now. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My pre-flight abort briefing with the CFI is that if we lose power below 700ft AGL, we're going to land on a suitable field 20° off the nose (after pitching for best-glide speed, 68kts in our plane). However, above 700ft AGL, I'm being taught that we are going to pitch for best-glide and turn to the airport and land at &quot;any available runway&quot;. The plane we're flying is C172S and we have never tried this at the airport, but in the air we did 360° turns with idle engine and 68 kts with only about ~300ft lost altitude. I was truly surprised about that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm still uneasy about returning to the field, though.&lt;/p&gt;&#xA;" OwnerUserId="540" LastActivityDate="2014-01-10T22:08:57.150" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="870" PostTypeId="2" ParentId="159" CreationDate="2014-01-10T22:26:47.837" Score="10" Body="&lt;p&gt;@Pondlife has good quotes and I'll supply some of the direct knowledge he requested.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Ground Stop&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Your destination airport cannot accommodate arrivals -- at all.  In this case, they will disallow all planes destined for that airport to take off from wherever they are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples of what might cause ground stops are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Weather impacting standard arrival routes, probably more than one.  Aircraft are already in holding patterns and they are running low on altitudes/fixes to put us, and/or those of us in holds are getting close to diverting for fuel.&lt;/li&gt;&#xA;&lt;li&gt;Airport or runway closure.  If you can't land, you probably shouldn't take off.&lt;/li&gt;&#xA;&lt;li&gt;All gates are occupied.  If planes cannot depart, there may be nowhere to park arrivals.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You'll note that many times you'll see ground stops described as &quot;Tier 1&quot;, &quot;Tier 2&quot;.  In short, the T1 ARTCCs are those that directly border with the ARTCC of the destination.  T2 ARTCCs are those bordering the T1 ARTCCs and so on.  Sometimes only T1 departure airports are affected by a ground stop, and sometimes it is everyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground stops are issued with update times, usually (in my experience) 45-60 minutes later.  They are subject to cancellation at any time, or extension with updated in another 60 minutes.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Ground Delays&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These are like the Ground Stops but the airport knows it can accommodate you, just not exactly when you planned to be there.  The reason is most often weather at the destination airport.  Runway closures, accidents, construction, plowing/de-icing can all cause these delays also.   &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;An example&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;In good weather, airport A may land 90 aircraft per hour.  The helpful airlines have scheduled 110 airplanes to land in one particular hour (no slots at this airport!).  Low clouds and high winds have moved in and now airport A can only land 40 airplanes per hour.  Now of the 110 airplanes, 70 of them will be delayed.  The airlines and ATC will work out which 70 planes those are, and which 40 planes will be allowed in that hour, and start issuing ground delay times.  Of course, these delays spill over into the next hour and cascade.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a ground delay program is in effect, you will get a &quot;Wheels up time&quot; from ATC, which is when you have to be airborne.  Not sooner, and not much later (3-5 minutes usually).  Getting into your spot in the arrival flow depends on you taking off at this time.  In these scenarios ATC can figure out how/when to get you to your destination, if this isn't the case, that is usually when the Ground Stop program gets started.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Gate Hold Procedure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There is too much happening out on the taxiways, and no room for you.  Stay at the gate!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons for gate holds:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;De-icing is in effect and not enough room for everyone to line up at once.&lt;/li&gt;&#xA;&lt;li&gt;The line to takeoff is too long&lt;/li&gt;&#xA;&lt;li&gt;Your departure fixes are closed/saturated (This one happens a lot in the NYC Tracon)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In these cases, ATC will issue you a time to start and pushback via clearance delivery (at big airports) or ground control (smaller airports).  Sometimes ramp control can be helpful and help coordinate things... usually not.  When your time is up, you push and taxi and contact ground control.  Not any different than normal except you are given a specific time to do it.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="15991" LastEditDate="2016-07-20T22:00:41.020" LastActivityDate="2016-07-20T22:00:41.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="871" PostTypeId="1" AcceptedAnswerId="872" CreationDate="2014-01-10T22:45:26.417" Score="10" ViewCount="1229" Body="&lt;p&gt;All things equal, from a standard traffic pattern at a towered airport, is it safer to do a short approach when approved by tower, or a normal one? Assume a Cherokee, Cessna 172, or similar small trainer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My gut is a short approach should be safer, because I stay closer to the airport in case something goes wrong and I can let up on the decent rate if I hit unexpected wind shifts. However, I descend at 1000fpm in a slip, instead of 500fpm with my nose pointing to the runway. The workload also tends to be higher because there is less time.&lt;/p&gt;&#xA;" OwnerUserId="526" LastEditorUserId="572" LastEditDate="2015-02-19T10:03:44.650" LastActivityDate="2015-02-19T10:03:44.650" Title="Is it safer to do a regular approach than a short approach?" Tags="&lt;flight-training&gt;&lt;landing&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="872" PostTypeId="2" ParentId="871" CreationDate="2014-01-10T22:57:39.753" Score="4" Body="&lt;p&gt;The safest approach to a normal landing is a &lt;a href=&quot;http://www.avweb.com/news/leadingedge/leading_edge_23_stabilized_approaches199047-1.html&quot; rel=&quot;nofollow&quot;&gt;stabilized approach&lt;/a&gt;, so it's going to depend a lot on you, your aircraft, and the day's conditions. If you're operating in a confined area, then that changes things a lot, and I'm not going to address that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also depends on your definition of a normal pattern and approach. The FAA &lt;a href=&quot;http://books.google.com/books?id=3HUhAgAAQBAJ&amp;amp;pg=PT127&amp;amp;lpg=PT127&amp;amp;dq=faa+downwind+traffic+pattern+distance&amp;amp;source=bl&amp;amp;ots=IWl2s84znv&amp;amp;sig=-FL6s2Pw4iR3lR1naIVbdCFO8jE&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=6XvQUt7qJcz2oAShrYCYDg&amp;amp;ved=0CF8Q6AEwBg#v=onepage&amp;amp;q=faa%20downwind%20traffic%20pattern%20distance&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;recommends you fly your downwind around ½ mile to 1 mile from the runway centerline&lt;/a&gt;, which should keep you fairly close to the airport anyway, and &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html#sx982ROBE&quot; rel=&quot;nofollow&quot;&gt;you should be turning base at least ¼ mile away from the runway threshold&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, &lt;strong&gt;a normal approach is going to be much safer&lt;/strong&gt;. As you point out in your question, a short approach often requires extreme descent rates or slips (or both), and results in a much shorter final; neither of those situations improve safety. Approaching with a high descent rate just so that you can reduce it if necessary doesn't strike me as a particularly good choice for normal operations, either.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-11T18:02:29.920" LastActivityDate="2014-01-11T18:02:29.920" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="875" PostTypeId="1" AcceptedAnswerId="878" CreationDate="2014-01-11T01:51:00.487" Score="8" ViewCount="3022" Body="&lt;p&gt;Assuming I've got the hardware and software that meets the FAA requirements for a BATD (Basic Aviation Training Device), what is the process I would go through to get the simulator certified? &lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="64" LastEditDate="2016-07-08T17:57:20.553" LastActivityDate="2018-08-31T07:55:37.973" Title="What is the process to get a simulator FAA certified for IFR training?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;flight-simulator&gt;&lt;faa-approval&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="876" PostTypeId="5" CreationDate="2014-01-11T01:52:26.207" Score="0" Body="&lt;p&gt;Instituto de Aeronáutica Civil de Cuba (or &quot;Civil Aviation Institute of Cuba&quot;) is the civil aviation authority of Cuba.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions concerning aviation law in the country of Cuba should be tagged IACC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see their website:  &lt;a href=&quot;http://www.iacc.gob.cu/&quot; rel=&quot;nofollow&quot;&gt;www.iacc.gob.cu&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T05:58:23.790" LastActivityDate="2014-01-11T05:58:23.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="877" PostTypeId="4" CreationDate="2014-01-11T01:52:26.207" Score="0" Body="Instituto de Aeronáutica Civil de Cuba (or &quot;Civil Aviation Institute of Cuba&quot;) is the civil aviation authority of Cuba." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T05:58:09.493" LastActivityDate="2014-01-11T05:58:09.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="878" PostTypeId="2" ParentId="875" CreationDate="2014-01-11T02:29:54.767" Score="9" Body="&lt;p&gt;The FAA &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/74438&quot;&gt;Advisory Circular 61-136&lt;/a&gt; contains the guidance for Aviation Training Devices, including the BATD's.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AC states that as long as the system has been FAA approved by the manufacturer (and in your case you say that it &quot;meets the FAA requirements&quot;), that no specific approval is required for training conducted under 14 CFR 61.  For use under 14 CFR 141 however, you would need specific FAA approval (see below).&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;14 CFR 61 Approval&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;You must simply follow the conditions specified in the AC:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5. APPROVAL OF BATD FOR USE UNDER PART 61.&lt;/strong&gt; To be approved for use for pilot   training and certification under part 61, a BATD should:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Be capable of providing procedural training in all elements for&#xA;  which it is to be used.  Those elements should be specified in an&#xA;  acceptable training curriculum or as specifically  authorized by the&#xA;  FAA and meet the description and suggested criteria outlined in this&#xA;  appendix.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. Have the following documents available for inspection by the&#xA;  student and instructor: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The list of ATD components as required by paragraph 3c, &lt;/li&gt;&#xA;  &lt;li&gt;A copy of AFS-800’s letter of approval and authorized use of the ATD, and &lt;/li&gt;&#xA;  &lt;li&gt;A copy of the QAG for the ATD being used.   &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;c. Successfully pass the start-up self-test described in paragraph&#xA;  8c(2). If the device is being used in a course of training for a pilot&#xA;  certificate or rating, a person authorized by the FAA to provide&#xA;  ground or flight instruction should observe this test. After the ATD&#xA;  self-test is complete, no other software of any kind may be started on&#xA;  the computer running the ATD software.   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Remain in the approved configuration during the training session.&#xA;  Authorized ATD  instruction may not proceed after a malfunction of the&#xA;  ATD system has occurred. The operator  must correct the ATD&#xA;  malfunction and repeat the start-up test described in paragraph c of&#xA;  this section before resuming authorized instruction. In addition, a&#xA;  BATD may be used in a training curriculum that provides for:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A similar scope and content of a syllabus that is used under part 141; &lt;/li&gt;&#xA;  &lt;li&gt;Instructional materials for flight events; &lt;/li&gt;&#xA;  &lt;li&gt;A means of showing progress, such as an outline of stage (phase) checks and criterion  levels of performance; and &lt;/li&gt;&#xA;  &lt;li&gt;The authorized use as approved in the AFS-800 letter of approval.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;14 CFR 141 Approval&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;141 Approval is almost the same, but must be approved by the school's POI (principle operations inspector):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;6. APPROVAL OF BATD FOR USE UNDER PART 141.&lt;/strong&gt; Local FSDO may approve  BATDs as part of an overall part 141 curriculum approval and&#xA;  certification process. Pilot schools that want to use a BATD as part&#xA;  of their training curriculum must notify their principal operations&#xA;  inspector (POI). The POI is responsible for approving how the BATD is&#xA;  to be used in the certificate holder’s part 141 curriculum. To be&#xA;  approved for use under part 141, a BATD should:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Be capable of providing training in all elements in which it will&#xA;  be used, as specified in the syllabus, and meet the description and&#xA;  suggested criteria outlined in this appendix.     b. Have the&#xA;  following documents available for inspection by the student and&#xA;  instructor:   &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The list of ATD components required in paragraph 3c, &lt;/li&gt;&#xA;  &lt;li&gt;A copy of AFS-800’s letter of approval and authorized use of the ATD, and &lt;/li&gt;&#xA;  &lt;li&gt;A copy of the QAG for the ATD being used.  &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;c. Successfully pass the start-up self-test described in paragraph 8c&#xA;  of this appendix. A  person authorized by the FAA to provide ground or&#xA;  flight instruction should observe this test. After the ATD self-test&#xA;  is complete, no other software of any kind may be started on the&#xA;  computer running the ATD software.   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Remain in the approved configuration during the training session.&#xA;  Authorized ATD  instruction may not proceed after a malfunction of the&#xA;  ATD system has occurred. The operator  must correct the ATD&#xA;  malfunction and repeat the start-up test described in paragraph c of&#xA;  this section before resuming authorized instruction.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;e. Be used in an integrated ground and flight training curriculum&#xA;  which provides for:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The scope and content of a curriculum in compliance with part 141, &lt;/li&gt;&#xA;  &lt;li&gt;The authorized use as approved in the AFS-800 letter of approval, &lt;/li&gt;&#xA;  &lt;li&gt;Instructional materials for flight events, and &lt;/li&gt;&#xA;  &lt;li&gt;An outline of stage (phase) checks and criterion levels of performance.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-11T02:29:54.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="879" PostTypeId="5" CreationDate="2014-01-11T02:56:52.753" Score="0" Body="&lt;p&gt;&lt;em&gt;Aircraft design&lt;/em&gt; describes the different choices that aircraft designers (typically aerospace engineers) make when creating an aircraft.  Most choices are a compromise between multiple important goals in the design of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag should be used for questions about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The positive and/or negative factors of a particular design&lt;/li&gt;&#xA;&lt;li&gt;Differences between two different designs&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2018-12-30T00:39:28.747" LastActivityDate="2018-12-30T00:39:28.747" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="880" PostTypeId="4" CreationDate="2014-01-11T02:56:52.753" Score="0" Body="Questions about the different choices that aircraft designers (typically aerospace engineers) make in order to create an aircraft." OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2018-12-30T13:10:04.287" LastActivityDate="2018-12-30T13:10:04.287" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="881" PostTypeId="5" CreationDate="2014-01-11T03:06:36.653" Score="0" Body="&lt;p&gt;Use this tag when the question is not specific to a particular category or type of aircraft, but is more general in nature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specific categories of aircraft that may be used instead are: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/airplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;airplane&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/rotorcraft&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rotorcraft&amp;#39;&quot; rel=&quot;tag&quot;&gt;rotorcraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/glider&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glider&amp;#39;&quot; rel=&quot;tag&quot;&gt;glider&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/lighter-than-air&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lighter-than-air&amp;#39;&quot; rel=&quot;tag&quot;&gt;lighter-than-air&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/powered-lift&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;powered-lift&amp;#39;&quot; rel=&quot;tag&quot;&gt;powered-lift&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/powered-parachute&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;powered-parachute&amp;#39;&quot; rel=&quot;tag&quot;&gt;powered-parachute&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/weight-shift-control&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;weight-shift-control&amp;#39;&quot; rel=&quot;tag&quot;&gt;weight-shift-control&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T05:56:56.300" LastActivityDate="2014-01-11T05:56:56.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="882" PostTypeId="4" CreationDate="2014-01-11T03:06:36.653" Score="0" Body="The aircraft tag should be used for general questions which do not apply to a particular category of aircraft." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T05:58:15.447" LastActivityDate="2014-01-11T05:58:15.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="883" PostTypeId="5" CreationDate="2014-01-11T03:10:08.657" Score="0" Body="&lt;p&gt;An autopilot is a system used to guide an aircraft without assistance from a person.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about how autopilots work or are designed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also: &lt;a href=&quot;http://en.wikipedia.org/wiki/Autopilot&quot; rel=&quot;nofollow&quot;&gt;Autopilot&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T18:46:14.273" LastActivityDate="2014-01-11T18:46:14.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="884" PostTypeId="4" CreationDate="2014-01-11T03:10:08.657" Score="0" Body="An autopilot is a system used to guide an aircraft without assistance from a person." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T18:46:01.227" LastActivityDate="2014-01-11T18:46:01.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="885" PostTypeId="2" ParentId="871" CreationDate="2014-01-11T03:18:41.660" Score="2" Body="&lt;p&gt;Oh, this one is hard to answer, but let me have a try:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will be no universal answer as it is very dependent on&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How likely are certain emergency situations to happen&lt;/li&gt;&#xA;&lt;li&gt;The Runway available&lt;/li&gt;&#xA;&lt;li&gt;Terrain below (obstacles, landingsights outside the airport, populated area or not)&lt;/li&gt;&#xA;&lt;li&gt;The aircrafts characteristics (ofcause we are talking only of SE)&lt;/li&gt;&#xA;&lt;li&gt;You&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and most probably even on some more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your chances to get to the 'safe' runway should you encounter an engine failure are much bigger and you will also be faster on ground in case of fire if you remain close to the field - both emergencies are very remote but allways to consider. I take them into account when planning to fly over Water or over congested areas according to FAR 91.119&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:&#xA;  (a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.&#xA;  [...]&#xA;  FAR 91.119&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A traffic pattern is obviously a maneuver necessary for takeoff and landing. But you are not asking about legal facts but about safety, so let's go ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We found out that a closer pattern will most probably give you the best chances if you have an engine failure or fire and there is no other safe spot to land then the runway. But that's not completely true because if you compare a 'normal' to a short approach ~70% of the pattern (~90% of the engines workload) will be exactly the same which even makes an engine failure or an fire on board more remote to happen during the phase of flight where you are closer tomthe runway as 'normal'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@Egid mentioned a stabilised approach,  which results in a lot of safety. He even called it the safest way to fly an approach - guess what my comment on this is, right, start reading at the top: it's dependent on blablabla ;) All right man, you're answer is basically correct and I practice it 90% of my landings but the runway available and obstacles sometimes make me think a different way. Assuming a short muddy grass strip : Stop talking about extra safety thanks to a short approach - suitable words were either funny or risky. Also a stabilised approach until 50ft would not be my first choice.  If I would approach this runway with nothing else in my mind than maximum safety I would chose a little longer final than usual, stabilise the airplane early - final configuration, all checklists done, on spped on glide path on centerline - but after clearing the obstacles deviate from the approach path to do a short field landing optimally with the aircraft fully stalled at touchdown on threshold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are aircraft you either fly stabilised or better leave on ground. An example would be the Cirrus aircraft, but honestly I have not enough experience on them to really consider them to be not suitable for steep dives into final. Anyway these and other agile aircraft are much safer to operate the 'normal' way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also a huge point to consider.  If I would sit there with the hands on the controls flying not further than a quarter mile from the runway afraid of my engine going off any second, I would rather visit the doctor but don't go flying.  There are these days where you are concerned of anything, check everything 3 times and take some extra precautions wherever possible. But then I've checked everything but my self prior this flight. You won't perform well if you are afraid of what you are doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I don't think that you are someone who's afraid but someone who wants to do his best to fly as safe as possible - a pilot who thinks that way he's supposed to do. But you're still a factor. Ask your self if you are familiar enough with the aircraft, the approach, the situation and feel comfortable to cut it short if you like to do so. Consider that there will be a higher workload (work / time) you will have to manage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all you need to think of a lot off points and I myself come to the result that I would brief and fly the approach I feel most comfortable with - easy isn't it? ;)&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-11T03:18:41.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="886" PostTypeId="2" ParentId="159" CreationDate="2014-01-11T04:36:52.117" Score="8" Body="&lt;p&gt;The FAA Air Traffic Organization has issued a booklet titled &quot;&lt;a href=&quot;http://www.fly.faa.gov/Products/Training/Traffic_Management_for_Pilots/TFM_in_the_NAS_Booklet_ca10.pdf&quot;&gt;Traffic Flow Management in &#xA;the National Airspace System&lt;/a&gt;&quot; which was specifically written for pilots and s flight operations personnel.  They cover Traffic Flow Management (TFM) in great detail (68 pages) but here is a small portion covering the most commonly used traffic management techniques.  Each section also includes an extensive &quot;How does it work&quot; sub-section which you can look at if you want more details.  I would &lt;strong&gt;&lt;em&gt;highly&lt;/em&gt;&lt;/strong&gt; recommend that any pilot read the entire booklet (while it is 63 pages, it is booklet format so it goes quickly)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;&lt;em&gt;GREAT&lt;/em&gt;&lt;/strong&gt; website that the FAA has allows you to see a list of, and the current status of all of the following programs in one place:  &lt;a href=&quot;http://www.fly.faa.gov/ois&quot;&gt;http://www.fly.faa.gov/ois&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Ground delay programs (GDP)&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Ground Delay Program (GDP) is a traffic management procedure  where&#xA;  aircraft are delayed at their departure airport in order to  manage&#xA;  demand and capacity at their arrival airport. Flights are  assigned&#xA;  departure times, which in turn regulates their arrival time  at the&#xA;  impacted airport.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GDP will normally be implemented at airports where capacity has  been&#xA;  reduced because of weather—such as low ceilings, thunderstorms  or&#xA;  wind—or when demand exceeds capacity for a sustained period.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GDPs are implemented to ensure the arrival demand at an airport  is&#xA;  kept at a manageable level to preclude extensive holding and to &#xA;  prevent aircraft from having to divert to other airports. They are &#xA;  also used in support of Severe Weather Avoidance Plan (SWAP).  (See&#xA;  section on SWAP.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Airspace flow programs (AFP)&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airspace Flow Programs (AFP) were introduced in Summer 2006  and&#xA;  marked a significant new step in en route traffic management.  The&#xA;  principal goal for the initial deployment was to provide enhanced  en&#xA;  route traffic management during severe weather events. An AFP  is a&#xA;  traffic management process that identifies constraints in the  en&#xA;  route system, develops a real-time list of flights that are filed into&#xA;  the  constrained area, and distributes EDCTs to meter the demand&#xA;  through  the area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Ground stops (GS)&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A ground stop (GS) is a procedure requiring aircraft that meet &#xA;  specific criteria to remain on the ground. The GS may be airport &#xA;  specific, related to a geographical area, or equipment related.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Severe weather avoidance plan (SWAP)&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;SWAP is a formalized program that is developed for areas susceptible &#xA;  to disruption in air traffic flows caused by thunderstorms. Each air &#xA;  traffic facility may develop its own strategy for managing the severe &#xA;  weather event. Their plan then becomes part of the overall daily &#xA;  operations plan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Special traffic management program (STMP)&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A STMP is a long-range strategic initiative that is implemented when &#xA;  a location requires special handling to accommodate above-normal &#xA;  traffic demand, e.g., Masters golf tournament, NBAA Convention, etc.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Gate hold&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Gate hold is not a traffic flow management technique, but is instead used by airports to keep you from starting engines and taxing just sit in line burning fuel when you can't takeoff due to a delay program.  It makes everybody's life better if you don't leave in the first place!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T06:12:52.973" LastActivityDate="2014-01-11T06:12:52.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="887" PostTypeId="1" AcceptedAnswerId="889" CreationDate="2014-01-11T06:32:58.703" Score="22" ViewCount="26508" Body="&lt;p&gt;What is a &quot;guarded&quot; frequency and how does it differ from a frequency that's unguarded?&lt;/p&gt;&#xA;" OwnerUserId="544" LastActivityDate="2018-09-22T18:01:21.243" Title="Why is 121.5 called &quot;guard&quot;?" Tags="&lt;radio-communications&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="888" PostTypeId="1" AcceptedAnswerId="903" CreationDate="2014-01-11T06:33:39.170" Score="33" ViewCount="4895" Body="&lt;p&gt;I know that they certify airplanes for lightning strikes (at least some of them anyway), but does it cause any damage to the airplane or to the electronics?  Are there any required inspections if an airplanes is struck by lightning?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airspacemag.com/flight-today/How-Things-Work-Lightning-Protection.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wWwEL.jpg&quot; alt=&quot;Airplane being struck by lightning&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-11T07:40:04.183" LastActivityDate="2018-12-06T07:00:55.040" Title="What happens when an airplane gets struck by lightning?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;aircraft-design&gt;&lt;aircraft-certification&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="889" PostTypeId="2" ParentId="887" CreationDate="2014-01-11T06:53:39.927" Score="24" Body="&lt;p&gt;It is called guard because everybody is supposed to listen/guard the frequency just in case someone has a problem.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Guard definitions:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;a state of caution, vigilance, or preparedness against adverse&#xA;  circumstances&lt;/li&gt;&#xA;  &lt;li&gt;watch over in order to protect or control.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0603.html&quot;&gt;AIM 6-3-1&lt;/a&gt;(h)(1) says (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;121.5 MHz and 243.0 MHz. Both have a range generally limited to line of sight. &lt;strong&gt;121.5 MHz is guarded&lt;/strong&gt; by direction finding stations and&#xA;  some military and civil aircraft. &lt;strong&gt;243.0 MHz is guarded&lt;/strong&gt; by military&#xA;  aircraft. &lt;strong&gt;Both 121.5 MHz and 243.0 MHz are guarded&lt;/strong&gt; by military&#xA;  towers, most civil towers, FSSs, and radar facilities. Normally ARTCC&#xA;  emergency frequency capability does not extend to radar coverage&#xA;  limits. If an ARTCC does not respond when called on 121.5 MHz or 243.0&#xA;  MHz, call the nearest tower or FSS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="65" LastEditDate="2015-03-04T18:34:53.837" LastActivityDate="2015-03-04T18:34:53.837" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="890" PostTypeId="5" CreationDate="2014-01-11T07:00:00.247" Score="0" Body="&lt;p&gt;An emergency is when an aircraft and/or its crew and passengers are in immediate danger, or when there is immediate danger to people on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emergencies have many possible causes, including ones outside the aircraft itself. For example (this is not a complete list):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Structural damage or failure&lt;/li&gt;&#xA;&lt;li&gt;Systems failures&lt;/li&gt;&#xA;&lt;li&gt;Flight into severe weather conditions&lt;/li&gt;&#xA;&lt;li&gt;Fire on board&lt;/li&gt;&#xA;&lt;li&gt;Pilot incapacitation&lt;/li&gt;&#xA;&lt;li&gt;Deliberate hijacking or sabotage&lt;/li&gt;&#xA;&lt;li&gt;Fuel shortage&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most aircraft have checklists and procedures for some specific emergencies such as engine failure, in-flight fires, and loss of pressurization. However, it is obviously impossible to plan for every possible scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an emergency occurs, the pilot may make a general mayday radio call or inform Air Traffic Control that he is &quot;declaring an emergency&quot;. An aircraft in distress has priority over all other air traffic and the pilot is generally allowed to take any action necessary to ensure the safety of the flight, even if that action might not be allowed in normal circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft cannot reach its original destination as planned because of an emergency, the pilot may choose to land at a different airport or make a forced landing if there is no other alternative.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0601.html&quot; rel=&quot;nofollow&quot;&gt;Emergency procedures&lt;/a&gt; (FAA Aeronautical Information Manual)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc1001.html&quot; rel=&quot;nofollow&quot;&gt;Emergencies&lt;/a&gt; (FAA ATC Orders)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="12720" LastEditDate="2016-02-08T16:23:49.367" LastActivityDate="2016-02-08T16:23:49.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="891" PostTypeId="4" CreationDate="2014-01-11T07:00:00.247" Score="0" Body="An emergency is any situation that threatens the safety of an aircraft, the people on board it, or people on the ground." OwnerUserId="97" LastEditorUserId="62" LastEditDate="2014-09-20T05:51:08.627" LastActivityDate="2014-09-20T05:51:08.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="892" PostTypeId="5" CreationDate="2014-01-11T07:01:33.787" Score="0" Body="&lt;p&gt;A runway is the long, rectangular surface area that aircraft land on and take off from. Larger runways are usually constructed entirely from artificial materials such as asphalt or concrete, but runways are also made by preparing natural surfaces such as grass, dirt, snow or even ice. The term &quot;water runway&quot; is sometimes used in seaplane operations, but a runway is normally understood to be on land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most runways have markings to provide information about the runway heading, touchdown zone, surface available for landings and so on. Additionally, many runways have lighting for use at night or in low visibility. Smaller runways in remote locations may have no markings or lighting of any kind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runways are orientated depending on the prevailing winds (aircraft almost always take off and land into the wind) and other factors such as terrain. They are numbered based on their magnetic heading: &quot;runway 18/36&quot; describes a north-south runway, referred to as &quot;runway three six&quot; when taking off to the north and &quot;runway one eight&quot; when taking off to the south. Parallel runways at the same airport usually have the same number with &quot;left&quot; and &quot;right&quot; appended, e.g. &quot;one eight left&quot; and &quot;three six right&quot; would refer to the same physical runway. If there are three parallel runways, they are designated &quot;left&quot;, &quot;center&quot; and &quot;right&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;active runway&quot; is the runway currently in use for takeoffs and landings; a large airport may have several active runways at once. The active runway is primarily determined by the current wind direction and can change at any time. At controlled airports this is managed by Air Traffic Control but at uncontrolled airports pilots decide themselves which runway to use and communicate with other pilots appropriately.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Runway&quot; rel=&quot;nofollow&quot;&gt;Runway&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://virtualskies.arc.nasa.gov/airport_design/5.html&quot; rel=&quot;nofollow&quot;&gt;Airport layout&lt;/a&gt; (NASA)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-22T21:52:24.870" LastActivityDate="2014-01-22T21:52:24.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="893" PostTypeId="4" CreationDate="2014-01-11T07:01:33.787" Score="0" Body="A runway is a &quot;defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft&quot; (ICAO definition)." OwnerUserId="97" LastEditorUserId="62" LastEditDate="2014-01-22T21:51:43.130" LastActivityDate="2014-01-22T21:51:43.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="894" PostTypeId="5" CreationDate="2014-01-11T07:03:56.910" Score="0" Body="&lt;p&gt;The term is sometimes used loosely as a synonym for cockpit instruments as a whole, in which context it can include engine instruments, navigational and communication equipment.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-11T18:12:36.750" LastActivityDate="2014-01-11T18:12:36.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="895" PostTypeId="4" CreationDate="2014-01-11T07:03:56.910" Score="0" Body="Flight instruments provide the pilot with information about the flight situation of that aircraft, such as altitude, speed and direction; and are of particular use in conditions of poor visibility, such as in clouds, when such information is not available from visual reference outside the aircraft." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-13T00:09:48.357" LastActivityDate="2014-01-13T00:09:48.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="896" PostTypeId="5" CreationDate="2014-01-11T07:04:45.587" Score="0" Body="&lt;p&gt;An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot aboard. Its flight is controlled either autonomously by onboard computers or by the remote control of a pilot on the ground or in another vehicle. The typical launch and recovery method of an unmanned aircraft is by the function of an automatic system or an external operator on the ground. and also referred to as an unpiloted aerial vehicle and a remotely piloted aircraft (RPA) by the International Civil Aviation Organization (ICAO), is an aircraft without a human pilot aboard. ICAO classify unmanned aircraft into two types under Circular 328 AN/190:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Autonomous aircraft – currently considered unsuitable for regulation due to legal and liability issues&#xA;Remotely piloted aircraft – subject to civil regulation under ICAO and under the relevant national aviation authority&lt;/li&gt;&#xA;&lt;li&gt;The typical launch and recovery method of an unmanned aircraft is by the function of an automatic system or an external operator on the ground. Historically, UAVs were simple remotely piloted aircraft, but autonomous control is increasingly being employed.[not in citation given]. The Nazi-German V-1 flying bomb flew autonomously powered by a pulsejet.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;They are usually deployed for military and special operation applications, but also used in a growing number of civil applications, such as policing and firefighting, and nonmilitary security work, such as inspection of power, pipelines, and real estate. UAVs are often preferred for missions that are too &quot;dull, dirty or dangerous&quot; for manned aircraft. There is also a growing enthusiast market for UAVs, particularly for videography and racing.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="34932" LastEditDate="2018-10-19T21:59:37.030" LastActivityDate="2018-10-19T21:59:37.030" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="897" PostTypeId="4" CreationDate="2014-01-11T07:04:45.587" Score="0" Body="An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without a human pilot on board. Its flight is controlled either autonomously by computers in the vehicle or under the remote control of a pilot on the ground or in another vehicle." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-05-28T05:20:16.790" LastActivityDate="2019-05-28T05:20:16.790" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="898" PostTypeId="5" CreationDate="2014-01-11T07:06:48.880" Score="0" Body="&lt;p&gt;A &lt;em&gt;helicopter&lt;/em&gt; is a kind of aircraft where the &lt;a href=&quot;/questions/tagged/airfoil&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airfoil&amp;#39;&quot; rel=&quot;tag&quot;&gt;airfoil&lt;/a&gt;s that generate lift are attached to one or more vertical or near-vertical spinning shafts, forming the helicopter's &lt;em&gt;main rotor&lt;/em&gt; assembly or assemblies.  This allows a helicopter to remain airborne even at low or zero forward speed, whereas a fixed-wing aircraft has to maintain a high forward speed in order for its wings to produce sufficient lift to keep it in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, helicopters can take off and land vertically, and, instead of needing a long &lt;a href=&quot;/questions/tagged/runway&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runway&amp;#39;&quot; rel=&quot;tag&quot;&gt;runway&lt;/a&gt;, they only require a small, circular &lt;a href=&quot;/questions/tagged/helipad&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helipad&amp;#39;&quot; rel=&quot;tag&quot;&gt;helipad&lt;/a&gt;, not much larger than the helicopter itself.  Helicopters are, therefore, invaluable for operations in dense urban or forested areas (where it would generally be impossible to find sufficient room for fixed-wing aircraft to take off or land), to or from small, remote sites such as offshore oil platforms (ditto), and for &lt;a href=&quot;/questions/tagged/military&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;military&amp;#39;&quot; rel=&quot;tag&quot;&gt;military&lt;/a&gt; close air support (where a helicopter can hover over the battlezone and provide continuous fire in support of ground units, whereas a fixed-wing aircraft has to fly over in multiple short passes that can leave gaps of no air support in between them).  Helicopters can also hover in midair above the ground, which allows them to be used to pick up and/or deliver supplies, equipment, and/or personnel without needing to land, if need be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters with only a single main rotor need some way of keeping the torque from the spinning rotor from spinning the helicopter itself around; the most common way of doing this is with a smaller &lt;a href=&quot;/questions/tagged/tail-rotor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail-rotor&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail-rotor&lt;/a&gt; that blows air sideways, but other methods also exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Helicopter&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-05-27T04:29:42.533" LastActivityDate="2019-05-27T04:29:42.533" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="899" PostTypeId="4" CreationDate="2014-01-11T07:06:48.880" Score="0" Body="A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would usually not be able to take off or land." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-11T07:54:27.950" LastActivityDate="2014-01-11T07:54:27.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="900" PostTypeId="5" CreationDate="2014-01-11T07:09:23.550" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-11T07:09:23.550" LastActivityDate="2014-01-11T07:09:23.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="901" PostTypeId="4" CreationDate="2014-01-11T07:09:23.550" Score="0" Body="Unpowered flight is the ability to stay airborne for a period of time without using any power source." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-11T18:11:35.587" LastActivityDate="2014-01-11T18:11:35.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="902" PostTypeId="2" ParentId="887" CreationDate="2014-01-11T07:33:14.373" Score="12" Body="&lt;p&gt;Two reasons:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, and most relevant today, all facilities are supposed to &quot;guard&quot; (monitor) the frequency if able. Most ATC facilities and Flight Service stations monitor 121.5MHz, as do many airliners or aircraft with two radios.  &lt;a href=&quot;https://aviation.stackexchange.com/a/889/64&quot;&gt;Lnafziger already gave you the relevant AIM paragraphs&lt;/a&gt; that talk about this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, &quot;guard frequencies&quot; in general radio terminology are frequencies that have extra protection in the band.&lt;br&gt;&#xA;This is done for two reasons: to prevent use of the guard channel from interfering with other channels, and/or to ensure that the guard channel is always clear and that adjacent channels won't &quot;bleed over&quot; and render it unusable. This mattered more in the days of tube radios with poor frequency alignment &amp;amp; confinement - modern radios bleed much less, but some frequencies are still afforded extra band protection.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;121.5MHz in the USA is guarded in both respects - monitored as Lnafziger describes, and afforded extra band protection (50KHz on either side, 121.425 - 121.475 MHz &amp;amp; 121.525 - 121.575 are unusable per &lt;a href=&quot;http://www.ramairskyways.com/html/Documents/AC90-50D_VHF.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 90-50&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-01-11T08:22:39.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="903" PostTypeId="2" ParentId="888" CreationDate="2014-01-11T07:35:37.507" Score="27" Body="&lt;p&gt;The vast majority of aircraft require an inspection, from small Cessna singles to Boeing airliners. Usually, they require at the very least:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A visual inspection of the aircraft for damage, particularly the nose, tail section and wingtips. Most of the time, the damage is easily visible as &quot;burn&quot; marks or erosion of parts of the skin.&lt;/li&gt;&#xA;&lt;li&gt;A check of the communication/navigation systems, both visually and functional testing&lt;/li&gt;&#xA;&lt;li&gt;A check of all avionics, including GPS systems&lt;/li&gt;&#xA;&lt;li&gt;Propeller should be removed and inspected by an A/P for damage&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine should be inspected by a procedure similar to the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Remove the engine from the aircraft and disassemble it.&lt;/li&gt;&#xA;&lt;li&gt;Inspect the engine for arcing and heat damage to the crankshaft,&#xA;main bearings, counterweights, camshaft lobes, bearings, gear teeth&#xA;and any other parts applicable to your engine. Any magnetic parts&#xA;should be degaussed following the specific procedure in your manual.&lt;/li&gt;&#xA;&lt;li&gt;Measure each other part to make sure it is within tolerances for your engine.&lt;/li&gt;&#xA;&lt;li&gt;Reassemble, then install the engine.&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;(depends on company) Send in an lightning strike report to your manufacturer&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Confirmation of compass being within 10 degrees of another (stricter for transport low visibility operations) after completion of repair/inspection works&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cessna 172R Maintenance Manual&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot;&gt;Aero Magazine -- Lightning Strikes: Protection, Inspection, and Repair&lt;/a&gt; (Boeing, Q4 2012)&lt;/li&gt;&#xA;&lt;li&gt;Continental Maintenance and Overhaul Manual: M-18&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-11T09:13:11.560" LastActivityDate="2014-01-11T09:13:11.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="904" PostTypeId="2" ParentId="808" CreationDate="2014-01-11T11:33:30.040" Score="6" Body="&lt;p&gt;The full FAA regulations covering controllers can be found at &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking through the table of contents (page 25 onwards), I couldn't find anything related.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also searched the document for the phrases: &lt;code&gt;forum&lt;/code&gt;, &lt;code&gt;internet&lt;/code&gt;, &lt;code&gt;online&lt;/code&gt;, &lt;code&gt;discuss&lt;/code&gt; - nothing relevant was found.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, the &lt;a href=&quot;http://www.atca.org/&quot; rel=&quot;nofollow&quot;&gt;ATCA&lt;/a&gt; (Air Traffic Control Association) has been running annual conferences on air traffic control for &lt;a href=&quot;http://www.atca.org/58annual&quot; rel=&quot;nofollow&quot;&gt;58 years&lt;/a&gt;, where they obviously discuss ATC; and they also have members of the FAA on the committee.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've searched Google too, and can't find anything relevant.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-21T04:47:00.800" LastActivityDate="2014-03-21T04:47:00.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="905" PostTypeId="2" ParentId="887" CreationDate="2014-01-11T11:39:38.207" Score="9" Body="&lt;p&gt;I wonder whether it comes from the French, where the verb &quot;guarder&quot; means &quot;to keep&quot; or &quot;to reserve&quot; or &quot;to keep in reserve&quot;. A &quot;guarded&quot; frequency would then mean &quot;a reserved frequency&quot; which makes perfect sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;http://en.wikipedia.org/wiki/Mayday#History&quot;&gt;&lt;code&gt;Mayday&lt;/code&gt; comes from the French&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="556" LastActivityDate="2014-01-11T11:39:38.207" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="906" PostTypeId="1" AcceptedAnswerId="907" CreationDate="2014-01-11T12:26:07.033" Score="21" ViewCount="2519" Body="&lt;p&gt;Supposing a pilot reports having a laser beam shone on them to ATC, what action should they take?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the pilot allowed to take evasive action?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can other planes request clearance to avoid the area?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-12-20T00:37:17.433" LastActivityDate="2014-12-20T00:37:17.433" Title="What must ATC do, following a reported laser sighting by a plane?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;laser-illumination&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="907" PostTypeId="2" ParentId="906" CreationDate="2014-01-11T12:26:07.033" Score="20" Body="&lt;p&gt;Here's what the regulations say ATC should do:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Broadcast on all appropriate frequencies a general caution warning every 5 minutes for 20 minutes following the last report;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Include information on the ATIS broadcast for one hour following the last report;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Report the incident through the Domestic Events Network (DEN), or to their overlying TRACON or ARTCC facility.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;As for the pilots, lasers are regarded as an emergency, so you &lt;em&gt;are&lt;/em&gt; permitted to take evasive action.&lt;/p&gt;&#xA;&lt;p&gt;Other aircraft are also permitted to request clearance to avoid the area.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Here are the relevant FAA orders:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAAO JO 7110.65&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;10-2-14. UNAUTHORIZED LASER ILLUMINATION OF AIRCRAFT&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;a. When a laser event is reported to an air traffic facility, broadcast on all appropriate frequencies a general caution warning every five minutes for 20 minutes following the last report.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;PHRASEOLOGY-&lt;/strong&gt;&lt;/em&gt; &lt;em&gt;UNAUTHORIZED LASER ILLUMINATION EVENT, (location), (altitude).&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;b. Terminal facilities must include reported unauthorized laser illumination events on the ATIS broadcast for one hour following the last report. Include the time, location, altitude, color, and direction of the laser as reported by the pilot.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt; All personnel can expect aircrews to regard lasers as an inflight emergency and may take evasive action to avoid laser illumination. Additionally, other aircraft may request clearance to avoid the area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/7210.3v.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAAO JO 7210.3&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;2-1-27. REPORTING UNAUTHORIZED LASER ILLUMINATION OF AIRCRAFT&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;All FAA Air Traffic Control facilities, Federal Contract Towers and Flight Service Stations shall report unauthorized laser illumination incidents through the Domestic Events Network (DEN), providing the following information:&lt;/p&gt;&#xA;&lt;p&gt;a. UTC date and time of event.&lt;/p&gt;&#xA;&lt;p&gt;b. Call Sign, or aircraft registration number.&lt;/p&gt;&#xA;&lt;p&gt;c. Type of aircraft.&lt;/p&gt;&#xA;&lt;p&gt;d. Nearest major city.&lt;/p&gt;&#xA;&lt;p&gt;e. Altitude.&lt;/p&gt;&#xA;&lt;p&gt;f. Location of event (e.g., latitude/longitude and/or Fixed Radial Distance (FRD)).&lt;/p&gt;&#xA;&lt;p&gt;g. Brief description of the event.&lt;/p&gt;&#xA;&lt;p&gt;h. Any other pertinent information.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;&lt;/em&gt; &lt;em&gt;Facilities without direct access to the DEN shall forward the information through the overlying TRACON or ARTCC facility&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-11T12:26:07.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="908" PostTypeId="1" AcceptedAnswerId="912" CreationDate="2014-01-11T12:42:07.597" Score="27" ViewCount="35667" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAAO JO 7110.65&lt;/a&gt;, §10-1-1 states that &amp;quot;pan-pan&amp;quot; can be used to indicate a state of urgency:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;a. An emergency can be either a &lt;em&gt;Distress&lt;/em&gt; or an &lt;em&gt;Urgency&lt;/em&gt; condition as defined in the &amp;quot;Pilot/Controller Glossary.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;b. A pilot who encounters a &lt;em&gt;Distress&lt;/em&gt; condition should declare an emergency by beginning the initial communication with the word &amp;quot;Mayday,&amp;quot; preferably repeated three times. For an &lt;em&gt;Urgency&lt;/em&gt; condition, the word &amp;quot;Pan-Pan&amp;quot; should be used in the same manner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Under what conditions might a pilot use the phrase &amp;quot;pan-pan&amp;quot;, versus &amp;quot;Mayday&amp;quot;?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-04-15T15:05:22.250" Title="When should the term &quot;pan-pan&quot; be used instead of &quot;Mayday&quot;?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;pan-pan&gt;&lt;phraseology&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="909" PostTypeId="2" ParentId="517" CreationDate="2014-01-11T12:58:17.187" Score="1" Body="&lt;p&gt;Land normally per the POH is the correct answer per accepted answer.  Just remember that your ground speed will be faster and roll out will be longer. You'll pass the turnoff you usually make with a headwind.&lt;/p&gt;&#xA;" OwnerUserId="53" LastActivityDate="2014-01-11T12:58:17.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="910" PostTypeId="1" AcceptedAnswerId="914" CreationDate="2014-01-11T14:31:44.873" Score="35" ViewCount="34461" Body="&lt;p&gt;In aeroplanes that are equipped for autoland and landing at an airport with a working and adequate instrument landing system for the conditions, why would a pilot choose not to use autoland?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I had to guess, I'd say it's due to some of the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Autoland is stressful and labour-intensive for pilots compared with flying the plane normally down to the ground in VMC.&lt;/li&gt;&#xA;&lt;li&gt;Autoland produces less comfortable or otherwise &quot;worse&quot; quality landings.&lt;/li&gt;&#xA;&lt;li&gt;Using autoland is less fun or enjoyable for the pilots.&lt;/li&gt;&#xA;&lt;li&gt;The use of autoland is restricted by aviation regulations.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But I don't have any sources to back up these claims.&lt;/p&gt;&#xA;&#xA;&#xA;" OwnerUserId="558" LastEditorUserId="946" LastEditDate="2014-06-30T19:44:31.613" LastActivityDate="2018-09-23T05:21:56.910" Title="Why don't pilots always use autoland?" Tags="&lt;autopilot&gt;&lt;flight-instruments&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="911" PostTypeId="2" ParentId="908" CreationDate="2014-01-11T14:34:51.030" Score="3" Body="&lt;p&gt;Mayday should be used if you or any passengers on board are in danger and need immediate assistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pan-Pan is used when a safety problem exists, which might not necessarily be related to your plane (eg if you see another aircraft/vehicle in danger or if you for example notice a fire on ground).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pan-Pan therefore informs potential rescuers (including emergency services and other craft in the area) that a safety problem exists whereas &quot;Mayday&quot; will call upon them to drop all other activities and immediately initiate a rescue attempt.&lt;/p&gt;&#xA;" OwnerUserId="213" LastActivityDate="2014-01-11T14:34:51.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="912" PostTypeId="2" ParentId="908" CreationDate="2014-01-11T14:47:26.070" Score="16" Body="&lt;p&gt;Oddly enough, the FARs and the AIM do not define these terms even though they use them frequently, but it is in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot Controller Glossary&lt;/a&gt; (see below).  This is one of those areas that I've never really been given specific training on and I guess figured that I would &quot;know it when I saw it&quot;.  The definitions kind of support that since they leave it to the discretion of the pilot:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EMERGENCY- A distress or an urgency condition.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DISTRESS (MAYDAY)- A condition of being threatened by serious and/or imminent&#xA;  danger and of requiring immediate assistance.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;URGENCY (PAN-PAN)- A condition of being concerned about safety and of requiring&#xA;  timely but not immediate assistance; a potential distress condition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Flight Safety released a report titled &lt;a href=&quot;http://flightsafety.org/ao/ao_mar_apr00.pdf&quot; rel=&quot;noreferrer&quot;&gt;Use of Standard Phraseology by Flight Crews and Air Traffic Controllers Clarifies Aircraft Emergencies&lt;/a&gt; which includes a quote from an official in which she says that there is a misconception among some pilots about the difference between declaring mayday and pan-pan:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have observed many cases where a mayday is given when pan-pan should&#xA;  be sufficient.  Many pilots do not realize that this distinction is&#xA;  ATC's way of prioritizing two or more aircraft with an emergency at&#xA;  the same time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;She also included some of the most important factors to consider when deciding to declare an emergency:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Is the aircraft in immediate danger?&lt;/li&gt;&#xA;  &lt;li&gt;Does the aircraft require immediate assistance?&lt;/li&gt;&#xA;  &lt;li&gt;Will the aircraft require priority handling during the approach or during any other phase of flight?&lt;/li&gt;&#xA;  &lt;li&gt;Will the aircraft need special assistance on the ground?&lt;/li&gt;&#xA;  &lt;li&gt;Does the crew need any assistance from other parties?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The most important thing though is not whether you declare exactly the right kind of emergency, but that you actually let them know when you need help.  Don't forget that you can also change your mind.  If you declared an Urgency condition and decide that you need more assistance/priority, you can always &quot;upgrade&quot; it to a Distress, and vice-versa. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="62" LastEditDate="2015-04-07T23:28:04.703" LastActivityDate="2015-04-07T23:28:04.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="913" PostTypeId="2" ParentId="829" CreationDate="2014-01-11T15:16:29.300" Score="2" Body="&lt;p&gt;A rough surface on the leading edge of the wing has a surprisingly large effect. I tried to answer a similar/related question on the Skeptics site:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skeptics.stackexchange.com/questions/17663/can-a-sandpaper-thick-layer-of-ice-reduce-lift-by-30-percent-and-increase-drag-u&quot;&gt;Can a sandpaper-thick layer of ice reduce lift by 30 percent and increase drag up to 40 percent?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="556" LastEditorUserId="-1" LastEditDate="2017-04-13T12:46:45.343" LastActivityDate="2014-01-11T15:16:29.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="914" PostTypeId="2" ParentId="910" CreationDate="2014-01-11T15:18:56.273" Score="40" Body="&lt;p&gt;There are a number of reasons why pilot don't use autoland all the time, even if the airport and aircraft are equipped with the right equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To name the two most important ones:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots need to practise their flying technique. If they would always&#xA;fly autopilot, they would lose the skills to fly. Skills that they&#xA;need when the autopilot does fail. There are phases of flight where&#xA;it is better or even required to let the autopilot do its job, but&#xA;landing is one the things pilot are allowed to and need to be capable&#xA;of doing themselves. Of course autoland needs to be practised as well.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Auto land requires very accurate ILS guidance. Even if the airport is&#xA;equipped with calibrated ILS Cat IIIb equipment (required for&#xA;autoland), the signals will be degraded by traffic that is operating&#xA;near the ILS antennas. Under low visibility circumstances, when&#xA;pilots cannot land visually, traffic spacing is increased and ground&#xA;vehicles are not allowed anywhere near the ILS antennas to ensure the&#xA;best possible signal quality. This is a standard part of the Low&#xA;Visibility Procedures (LVP) of all airports. The downside of this is&#xA;that the capacity of the airport is reduced. If autoland would be&#xA;performed while there is no ILS signal protection, the effects can be&#xA;&lt;a href=&quot;http://www.youtube.com/watch?v=0rn-iI7wX-Y&quot; rel=&quot;noreferrer&quot;&gt;spectacular&lt;/a&gt; at best or fatal at worst.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/051iJ.jpg&quot; alt=&quot;Singapore airlines 777-3000ER incident in Munich (by BFU)&quot; title=&quot;Automatic landing with unprotected ILS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Photo by BFU, incident report &lt;a href=&quot;http://www.bfu-web.de/EN/Publications/Investigation%20Report/2011/FactualReport_11_EX010_B777_Munic.pdf?__blob=publicationFile&quot; rel=&quot;noreferrer&quot; title=&quot;BFU report of SIA B777-300ER incident at Munich&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="72" LastEditDate="2014-01-11T21:48:51.600" LastActivityDate="2014-01-11T21:48:51.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="915" PostTypeId="2" ParentId="910" CreationDate="2014-01-11T15:35:58.377" Score="12" Body="&lt;p&gt;Autoland is typically only used when it absolute has to, which means when the weather dictates or when it needs to be used for currency requirements.  ATC doesn't care if you are going to do one, but I have heard guys give courtesy calls to the tower letting them know they'd be autolanding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest pain with autoland is that it is a monitored approach.  My only experience with those are in Category II ILS approaches (though my aircraft did not have autoland capability).  Monitored approaches are higher workload and are briefed and flown differently than normal approaches*.  As noted by another answer, when you are going to fly an ILS to cat II or III minimums, the ground controllers need to be protecting the ILS critical areas to guarantee the glideslope quality if you are going to follow it below cat I minimums.  This may require coordination with the tower controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, other pilots I've asked about autolands in Boeing widebody aircraft have all told me some variation of not liking to autoland unless they have to do one per company procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*&lt;sub&gt;Feel free to follow &lt;a href=&quot;https://aviation.stackexchange.com/questions/966/what-is-a-monitored-approach&quot;&gt;&quot;What is a monitored approach?&quot;&lt;/a&gt; in another question and read more about specific question.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-12T09:51:50.827" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="916" PostTypeId="2" ParentId="829" CreationDate="2014-01-11T16:21:39.687" Score="7" Body="&lt;p&gt;Mud dauber wasps are credited for at least two total losses: &lt;a href=&quot;http://en.wikipedia.org/wiki/Birgenair_Flight_301&quot;&gt;Birgenair Flight 301&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Florida_Commuter_Airlines_crash&quot;&gt;Florida Commuter Airlines Flight 65&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airfoil soiling can make a large difference to performance. I don't operate aircraft, but I have operated wind turbines. Older stall-regulated wind turbines can take a performance hit of &lt;a href=&quot;http://www.renewableenergyfocus.com/view/3243/o-m-for-wind-turbine-blades/&quot;&gt;20%&lt;/a&gt; if they're not kept clean.&lt;/p&gt;&#xA;" OwnerUserId="560" LastActivityDate="2014-01-11T16:21:39.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="917" PostTypeId="5" CreationDate="2014-01-11T18:39:09.140" Score="0" Body="&lt;p&gt;Radio in various forms and using different frequencies is widely used in aviation for aircraft to communicate with each other and with air traffic control or other ground stations. Most voice communication is either VHF, HF, or UHF:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;VHF&lt;/strong&gt; (&lt;strong&gt;V&lt;/strong&gt;ery &lt;strong&gt;H&lt;/strong&gt;igh &lt;strong&gt;F&lt;/strong&gt;requency) communication uses a dedicated band of frequencies from 118 through 137 megahertz (MHz), in a region of the spectrum known as the &lt;em&gt;airband&lt;/em&gt; (which also includes an adjacent range of frequencies from 108 through 117.95 MHz used by &lt;a href=&quot;/questions/tagged/vor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vor&amp;#39;&quot; rel=&quot;tag&quot;&gt;vor&lt;/a&gt; stations for &lt;a href=&quot;/questions/tagged/radio-navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radio-navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;radio-navigation&lt;/a&gt; purposes, as well as for the &lt;a href=&quot;/questions/tagged/localizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;localizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;localizer&lt;/a&gt; portion of an &lt;a href=&quot;/questions/tagged/ils&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ils&amp;#39;&quot; rel=&quot;tag&quot;&gt;ils&lt;/a&gt; system).  Most radio traffic to and from civilian aircraft is VHF, except over the oceans or in extremely remote or mountainous areas (VHF transmissions are line-of-sight, meaning that they cannot, under normal circumstances, be used to communicate with stations or aircraft beyond the horizon).  A dedicated &lt;a href=&quot;/questions/tagged/emergency&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;emergency&amp;#39;&quot; rel=&quot;tag&quot;&gt;emergency&lt;/a&gt;, or &quot;guard&quot;, channel exists at 121.5 MHz.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;HF&lt;/strong&gt; (&lt;strong&gt;H&lt;/strong&gt;igh &lt;strong&gt;F&lt;/strong&gt;requency) communication uses a number of frequency bands scattered throughout the portion of the spectrum from 2 to 30 MHz.  Unlike VHF transmissions, transmissions in the HF bands reflect off the Earth's upper atmosphere, making them useful for communicating with aircraft or ATC facilities beyond the horizon.  Like the VHF band, the HF bands include a guard channel, located at 2.182 MHz.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;UHF&lt;/strong&gt; (&lt;strong&gt;U&lt;/strong&gt;ltra &lt;strong&gt;H&lt;/strong&gt;igh &lt;strong&gt;F&lt;/strong&gt;requency) communication uses a dedicated band from 225 MHz through 400 MHz, and is used almost exclusively by &lt;a href=&quot;/questions/tagged/military&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;military&amp;#39;&quot; rel=&quot;tag&quot;&gt;military&lt;/a&gt; aircraft (as the higher frequency of the signal allows the use of smaller and lighter transmitters, making it easier to set up an ATC station in the field), who use it for the same purposes for which civilian aircraft use VHF; it is legal, in most countries, to install a UHF radio in a civilian aircraft, but there is little point in doing so unless you're planning to talk to military aircraft.  The main civilian use of this UHF band is for ILS glideslope transmitters, which are not generally used, or useful, for voice communications.  The UHF guard channel is located at 243 MHz.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other frequencies may also be used for voice and/or data transmissions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Light aircraft are typically equipped only for voice communication; airliners and other larger aircraft frequently have telemetry systems that provide data links to the ground. Some countries may require pilots to have a specific license and/or training before being allowed to use aircraft radio transmitters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about radio communication systems on board aircraft, including topics like frequencies, radio procedures, equipment, phraseology and so on. It &lt;em&gt;may&lt;/em&gt; also be appropriate for questions about ground-based radio navigation aids like VORs; those questions should usually be tagged &lt;a href=&quot;/questions/tagged/navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;navigation&lt;/a&gt; (or, if one exists, the tag for the specific type of navaid - for instance, &lt;a href=&quot;/questions/tagged/vor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vor&amp;#39;&quot; rel=&quot;tag&quot;&gt;vor&lt;/a&gt;), but in some cases both tags may be useful (e.g. voice communication over a VOR).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see the Wikipedia articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Radio&quot; rel=&quot;nofollow noreferrer&quot;&gt;Radio in general&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Very_high_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;VHF radio&lt;/a&gt; (&lt;a href=&quot;https://en.wikipedia.org/wiki/Airband&quot; rel=&quot;nofollow noreferrer&quot;&gt;The VHF airband&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/High_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;HF radio&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ultra_high_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;UHF radio&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-08-10T00:12:09.590" LastActivityDate="2019-08-10T00:12:09.590" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="918" PostTypeId="4" CreationDate="2014-01-11T18:39:09.140" Score="0" Body="Radio is the primary way that pilots communicate with air traffic control and with other aircraft." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-01-11T18:52:21.697" LastActivityDate="2014-01-11T18:52:21.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="919" PostTypeId="5" CreationDate="2014-01-11T19:10:07.570" Score="0" Body="&lt;p&gt;An airport is any facility in a specific location where aircraft perform &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt;s. That includes &lt;a href=&quot;/questions/tagged/helipad&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helipad&amp;#39;&quot; rel=&quot;tag&quot;&gt;helipad&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/seaplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;seaplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;seaplane&lt;/a&gt; bases, but not &lt;a href=&quot;/questions/tagged/aircraft-carrier&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-carrier&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-carrier&lt;/a&gt;s (which have no fixed position). The exact terminology used for airports may be different in different countries. &lt;a href=&quot;/questions/tagged/general-aviation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;general-aviation&amp;#39;&quot; rel=&quot;tag&quot;&gt;general-aviation&lt;/a&gt; airports and private runways are sometimes referred to as &lt;em&gt;airfields&lt;/em&gt; or &lt;em&gt;airstrips&lt;/em&gt;, and &lt;a href=&quot;/questions/tagged/military&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;military&amp;#39;&quot; rel=&quot;tag&quot;&gt;military&lt;/a&gt; airports are often called &lt;em&gt;air bases&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports vary widely in size from large international commercial hubs with multiple &lt;a href=&quot;/questions/tagged/runways&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runways&amp;#39;&quot; rel=&quot;tag&quot;&gt;runways&lt;/a&gt; to smaller general aviation airfields and private grass strips. Airports can provide many different facilities for &lt;a href=&quot;/questions/tagged/passenger&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;passenger&amp;#39;&quot; rel=&quot;tag&quot;&gt;passenger&lt;/a&gt;s, &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt;, and aircraft, depending on their size; e.g., passenger terminals, refueling, maintenance, ground transport links, hangars, etc..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about how aircraft operate in and around airports, and for questions about airport operations. You may be referred to &lt;a href=&quot;https://travel.stackexchange.com&quot;&gt;Travel Stack Exchange&lt;/a&gt; if you ask about something related to business practices or non-aviation activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-11T06:53:39.593" LastActivityDate="2019-10-11T06:53:39.593" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="920" PostTypeId="4" CreationDate="2014-01-11T19:10:07.570" Score="0" Body="Questions about the aviation aspects of airports. Questions focused on the passenger aspects should be asked at Travel.SE." OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-11T01:47:45.893" LastActivityDate="2019-10-11T01:47:45.893" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="921" PostTypeId="1" AcceptedAnswerId="927" CreationDate="2014-01-11T20:16:34.667" Score="31" ViewCount="14220" Body="&lt;p&gt;In a recent flight on an Airbus A380 I noticed that its ailerons are split into three segments which move independently. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What advantages does this design have? Do other aircraft have split ailerons (or other control surfaces)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y4fqp.jpg&quot; alt=&quot;Multiple ailerons on an Airbus A380&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="16" LastEditorUserId="39" LastEditDate="2014-01-11T20:44:27.223" LastActivityDate="2018-11-03T16:09:35.260" Title="Why do some aircraft have multiple ailerons per wing?" Tags="&lt;aircraft-design&gt;&lt;airbus&gt;&lt;ailerons&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="922" PostTypeId="1" CreationDate="2014-01-11T20:17:08.297" Score="8" ViewCount="468" Body="&lt;p&gt;I'm wondering if it is it ok to use a consumer tablet and electronic charts (e.g. within the &lt;a href=&quot;https://itunes.apple.com/us/app/air-navigation-pro/id301046057?mt=8&quot; rel=&quot;nofollow&quot;&gt;AirNav Pro app&lt;/a&gt;) instead of the paper version for recreational VFR single-piston flights? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: to clarify, my question is indeed about &lt;em&gt;official, up-to-date&lt;/em&gt; charts, accessed with consumer hardware (I mention AirNav Pro, but it could well be any pdf reader for that purpose) as opposed to paper medium.&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="69" LastEditDate="2014-01-18T17:14:32.953" LastActivityDate="2014-01-19T10:39:38.467" Title="Is it ok to use an iPad (or similar consumer hardware) and electronic charts for GA in Europe?" Tags="&lt;visual-flight-rules&gt;&lt;easa-regulations&gt;&lt;aeronautical-charts&gt;&lt;efb&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="923" PostTypeId="1" AcceptedAnswerId="940" CreationDate="2014-01-11T20:49:43.373" Score="12" ViewCount="3083" Body="&lt;p&gt;I've read a couple of times that &quot;own-ship position display&quot; is not authorized for use on Class 1 or 2 EFBs (by the FAA), and that both the FAA and EASA are cautioning against that feature's use on EFBs in general. &lt;em&gt;Own-ship position is an aircraft's GPS position displayed against georeferenced charts and diagrams.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the use of a portable device - iPad or otherwise - should not be enough for primary navigation, but &lt;strong&gt;what safety concerns do the authorities have with own-ship display?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specific accident reports or official citations would be great.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="14897" LastEditDate="2021-03-02T12:15:03.130" LastActivityDate="2021-03-02T12:15:03.130" Title="What concerns do the FAA and EASA have in 2014 with &quot;own-ship position display&quot; on EFBs?" Tags="&lt;navigation&gt;&lt;easa&gt;&lt;efb&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="924" PostTypeId="5" CreationDate="2014-01-11T20:55:24.943" Score="0" Body="&lt;p&gt;An &lt;em&gt;Electronic Flight Bag&lt;/em&gt; (EFB) is typically a small, general-purpose, portable computer or tablet device that pilots and flight crews can use to perform or support tasks while in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most commonly, EFBs contain software to present charts, instrument approach procedures, checklists, and manuals.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-11T22:42:44.693" LastActivityDate="2014-01-11T22:42:44.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="925" PostTypeId="4" CreationDate="2014-01-11T20:55:24.943" Score="0" Body="Electronic Flight Bags are small, portable computers that flight crews can use while performing in-flight tasks." OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-11T22:42:33.927" LastActivityDate="2014-01-11T22:42:33.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="926" PostTypeId="2" ParentId="921" CreationDate="2014-01-11T21:05:45.180" Score="7" Body="&lt;p&gt;I don't know the specific rationale in this case, but if you think about mechanical advantage, the farther an aileron is out from the center of gravity, the more roll effect will have on the airplane. You'll notice in the image that the outer aileron is deflected less than the inner aileron, even though they are probably producing roughly the same roll moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A benefit I see is that it undoubtedly reduces wing-loading at the far end of the wings, and therefore reduces stress/flex on the wing during turns. This could be very important for an aircraft as massive and heavy as an A380, but less important for smaller aircraft where the wing-load is naturally less.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2014-01-11T21:05:45.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="927" PostTypeId="2" ParentId="921" CreationDate="2014-01-11T21:25:01.293" Score="29" Body="&lt;h2&gt;General Reasons&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are three main reasons for having multiple ailerons per wing on large aircraft:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Aileron Reversal&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;On a large aircraft, at high speeds a deflected aileron can twist the wing enough to cause a net roll torque opposite to the one intended.  The further out on the wing an aileron is, the more likely this problem is to arise.  For high-speed aircraft, this necessitates an outboard/inboard aileron, with the outboard being locked out at a certain speed limit. On the Airbus A380, the downwards motion of the outward aileron is locked out at 240 KIAS, and upward motion at 300 KIAS.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Systems Redundancy&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Another issue is that on most large aircraft, it is simply infeasible to have cables running through the aircraft, so hydraulic systems are used instead. Having ailerons split would allow for more redundancy of system failures, allowing more controllability in these failure conditions.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Load Alleviation Function&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Building on what Bret Copeland has already discussed in his answer, multiple ailerons can be used by fly-by-wire computers to flex the aircraft's wings in a specific manner to allow for less loading on the wing during cruise (counteracts the wing's natural tendency to flex upwards), as well as allowing for dynamic turbulence alleviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the examples of using this is in Airbus's Safety First magazine (&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/2275.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;July 2012&lt;/a&gt;), where they use the flexibility of having three ailerons to tune out lateral accelerations in the rear of the aircraft changing the gains of each of the controls. By being able to move the centre aileron a fraction after the inner aileron, they managed to avoid these initial shifts during flight testing of the A380.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Other Aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The majority of airliners have multiple ailerons, however in some instances (such as the Airbus A310), there is no outboard aileron -- this function is replaced by spoilers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example of using computers on multiple ailerons is the Boeing 747-8, with the use of the outboard aileron to fix issues relating to the development of flutter in certain extremes of the flight envelope, called the Outboard Aileron Modal Suppression (OAMS) system.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="34686" LastEditDate="2018-11-03T11:46:34.173" LastActivityDate="2018-11-03T11:46:34.173" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="928" PostTypeId="2" ParentId="908" CreationDate="2014-01-11T21:52:53.497" Score="6" Body="&lt;p&gt;The rule of thumb I was given when learning to fly (not in the US) was that mayday means &quot;this aircraft is in immediate danger and I need assistance&quot;, whereas pan-pan means &quot;I have an urgent safety issue but the aircraft is not in immediate danger&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Put another way, mayday always means that your own aircraft is in distress, but pan-pan is appropriate for reporting other aircraft in distress, ships or other vessels in distress, passenger emergencies aboard your own aircraft (someone has a heart attack and you need a diversion immediately) and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I think this is a rather grey area. For example, a few months ago a passenger &lt;a href=&quot;http://www.cnn.com/2013/11/14/us/florida-plane-rescue/&quot;&gt;jumped from a light aircraft in Florida&lt;/a&gt;. According to the definition I was taught, the pilot should have made a pan-pan call because there was no immediate danger to the aircraft. In fact, he made a mayday call, which might still have been very appropriate because if the pilot was so shaken (understandably) that he needed vectors or other immediate assistance in order to land safely then the aircraft was indeed in danger, thus justifying a mayday call.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-11T21:52:53.497" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="929" PostTypeId="5" CreationDate="2014-01-11T22:18:28.200" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-11T22:18:28.200" LastActivityDate="2014-01-11T22:18:28.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="930" PostTypeId="4" CreationDate="2014-01-11T22:18:28.200" Score="0" Body="Use this tag for questions regarding the certification of aircraft. If your question is regarding regulations or a specific country, please add the relevant tag and state so in your question." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-11T22:26:31.093" LastActivityDate="2014-01-11T22:26:31.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="931" PostTypeId="1" CreationDate="2014-01-11T22:22:27.807" Score="18" ViewCount="3220" Body="&lt;p&gt;A 15 hour flight across the Pacific obviously requires more fuel than a 7.5-hour transatlantic flight.  How significant is the hourly fuel consumption increase due to the additional fuel carried at the beginning of the longer flight? Another way of asking the question would be: How much more more fuel do you need to carry (in a typical heavy plane such as the B747-400) for a flight that is twice as long?&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="69" LastEditDate="2014-01-13T05:05:36.157" LastActivityDate="2015-10-12T01:01:37.747" Title="How does flight duration affect the hourly fuel consumption in heavy aircraft?" Tags="&lt;flight-planning&gt;&lt;aircraft-performance&gt;&lt;fuel&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="932" PostTypeId="5" CreationDate="2014-01-11T23:20:41.747" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-11T23:20:41.747" LastActivityDate="2014-01-11T23:20:41.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="933" PostTypeId="4" CreationDate="2014-01-11T23:20:41.747" Score="0" Body="This tag should be used for questions specific to operations on single-engine aircraft. If a question equally applies to both singles and multi-engine aircraft, this tag should not be used." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-11T23:56:59.863" LastActivityDate="2014-01-11T23:56:59.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="934" PostTypeId="2" ParentId="931" CreationDate="2014-01-12T01:13:37.400" Score="23" Body="&lt;h1&gt;General Answer&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The heavier the airplane, the more fuel it will burn in a given amount of time.  Therefore, if you takeoff with enough fuel to fly further, you will be burning more fuel in each corresponding hour than if you took off at a lighter weight to fly a shorter distance.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Example&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I don't have performance information for the 747, but I can give you an example for a G-IV corporate jet.  Instead of comparing a short trip to a longer trip, I planned the same trip with different amounts of fuel in order to make the airplane heavier.  I planned the flight for the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flight Conditions&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fly from Los Angeles to Detroit, using the same route and average Boeing winds for July&lt;/li&gt;&#xA;&lt;li&gt;Climb to and maintain the optimum altitude, with step climbs where appropriate&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Trip 1: Climb initially to FL450 and stay there for the entire flight (the optimum altitude for this weight)&lt;/li&gt;&#xA;&lt;li&gt;Trip 2: Climb initially to FL410 and then climb to FL450 2:32 into the flight (the optimum altitude the weight initially followed by a climb once the optimum altitude has changed)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Fuel:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Trip 1: Takeoff with enough to land with a 1:30 reserve - 59,000 lb. takeoff weight&lt;/li&gt;&#xA;&lt;li&gt;Trip 2: Takeoff with max fuel, landing with a 5:39 reserve - 73,000 lb. takeoff weight&lt;/li&gt;&#xA;&lt;li&gt;Taxi fuel is not included in the first hour burns, but climb fuel is.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Results&lt;/h2&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;          Trip 1      Trip 2  &#xA;Hour     Fuel Burn    Fuel Burn     Diff&#xA; 1        4,212         4,844      +13.7 %&#xA; 2        2,536         3,088      +21.8 %&#xA; 3        2,411         3,123      +29.5 %&#xA; 4        2,163         2,103      -2.8 %  &#xA; Total    11,722        13,558     +15.7 %   &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;h2&gt;Summary&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As you can see, the fuel burn is significantly higher in the first 3 hours due to the additional fuel that we were carrying (and therefore the higher weight of the aircraft).  Hour 4 is almost the same because of the idle power descent used in the planning software.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-10T18:29:20.983" LastActivityDate="2014-04-10T18:29:20.983" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="935" PostTypeId="2" ParentId="922" CreationDate="2014-01-12T01:56:49.827" Score="1" Body="&lt;p&gt;No, these kind of apps (AirNav, VFRNAV etc.) are not meant to replace paper charts. You'll find phrases like this on most of the websites which offer those apps you will find paragraphs like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Please note that this software is not intended to replace a certified navigation device. You should always use official aeronautical documentation when preparing and performing a flight. You should always use certified navigation devices when performing a flight. [Source: &lt;a href=&quot;https://itunes.apple.com/us/app/air-navigation-pro/id301046057?mt=8&quot; rel=&quot;nofollow&quot;&gt;https://itunes.apple.com/us/app/air-navigation-pro/id301046057?mt=8&lt;/a&gt; ]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is certified software like for example Jeppesen Mobile TC available.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-01-19T10:39:38.467" LastActivityDate="2014-01-19T10:39:38.467" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="936" PostTypeId="2" ParentId="923" CreationDate="2014-01-12T02:30:57.787" Score="6" Body="&lt;p&gt;I can't speak for EASA, but as far as the FAA the short version (from &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1020099&quot; rel=&quot;noreferrer&quot;&gt;AC 120-76B&lt;/a&gt;) is that &lt;code&gt;In-flight depiction of own-ship position is classified as a major safety effect and cannot be formally authorized for use on a Class 1 or Class 2 EFB.&lt;/code&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically the only kind of EFB that the FAA wants displaying own-ship position in flight is a Class 3 system (basically a permanently-installed piece of hardware that's gone through all the certification and testing requirements of any other piece of installed navigation equipment, like for example your panel-mount GPS or an approved MFD like a &lt;a href=&quot;https://buy.garmin.com/en-US/US/in-the-air/avionics-safety/mfd-pfd/gmx-200/prod6422.html&quot; rel=&quot;noreferrer&quot;&gt;Garmin GMX 200&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can find the FAA hasn't given an official reason for this (I went on quite a hunt), but I suspect it is out of an overabundance of caution: Class 3 EFBs are subject to strict design and change controls (like any other TSO'd avionics hardware), whereas iDevices, android tables, laptops, and their internal/plug-in/wireless GPS receivers are not.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has no way of ensuring that changes (like say a Stratus firmware update or an iOS update) won't adversely affect the accuracy of own-ship position display, nor can they guarantee that the EFB software will correctly detect GPS errors and disable own-ship position display. They would prefer you not have the display at all than rely on possibly inaccurate information and wind up flying through airspace you shouldn't be in (or worse, flying into an obstruction) because you were trusting your EFB's position display.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A tiny bit of light at the end of the rainbow, at least for us light General Aviation piston folks:&lt;br&gt;&#xA;AC 120-76B is specifically aimed at part 121, 125, 135, 91F, and 91K operators (i.e. &quot;Not light GA&quot;).&lt;br&gt;&#xA;The rest of us Part 91 folks are supposed to look at &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/73540&quot; rel=&quot;noreferrer&quot;&gt;AC 91-78&lt;/a&gt; (which talks about EFBs and removal of paper from the cockpit), and that Advisory Circular is blissfully silent on the subject of own-ship position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That seems to imply that you can strap your iPad to your Cessna's yoke and turn on own-ship position display and not incur the wrath of the FAA - &lt;a href=&quot;http://ipadpilotnews.com/2013/09/ipad-legal-briefing-for-pilots/&quot; rel=&quot;noreferrer&quot;&gt;an interpretation you can find others on the internet agreeing with&lt;/a&gt; - though it should certainly not be considered a navigational reference (merely &quot;an aid to situational awareness&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that if you don't &lt;em&gt;display&lt;/em&gt; own-ship position data there's nothing that says you can't &lt;em&gt;use&lt;/em&gt; it -- e.g. by turning off the little airplane graphic but still centering your map based on your GPS information. I know ForeFlight has this capability.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Standard Disclaimer:&lt;/strong&gt;&lt;br&gt;&#xA;  I'm not a lawyer and I don't work for the FAA. My interpretation of regulations is worth exactly nothing. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-12T02:36:59.707" LastActivityDate="2014-01-12T02:36:59.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="937" PostTypeId="5" CreationDate="2014-01-12T04:53:10.210" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-12T04:53:10.210" LastActivityDate="2014-01-12T04:53:10.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="938" PostTypeId="4" CreationDate="2014-01-12T04:53:10.210" Score="0" Body="&quot;Pan-pan&quot; is a signal used to indicate an urgent situation where there is no immediate danger to aircraft or life." OwnerUserId="567" LastEditorUserId="567" LastEditDate="2014-01-12T13:55:05.070" LastActivityDate="2014-01-12T13:55:05.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="939" PostTypeId="1" AcceptedAnswerId="1347" CreationDate="2014-01-12T04:54:49.407" Score="25" ViewCount="9756" Body="&lt;p&gt;At first I wasn't even sure if any airlines flew southern Pacific great circle route flights, but it looks like Qantas (&lt;a href=&quot;http://flightaware.com/live/flight/QFA27/history/20140111/0150Z/YSSY/SCEL&quot;&gt;QFA27&lt;/a&gt;) operates a flight between Sydney and Santiago, Chile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For northern Pacific greate circle routes, you are flying near Canada/Alaska and then Russia for most of the flight, so you have some airports you could potentially divert to if an emergency arose. I've search online for more details about how this works for these flight, but haven't had much luck finding information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any point on the southern Pacific great circle route for flights to divert to? Or is there not really any backup plan if something goes wrong? Are there specific requirements that must be met for an aircraft to fly this route?&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="69" LastEditDate="2014-01-26T16:45:11.157" LastActivityDate="2015-08-20T10:22:28.493" Title="Are there diversion points for southern Pacific great circle route flights?" Tags="&lt;flight-planning&gt;&lt;airline-operations&gt;&lt;oceanic&gt;&lt;casa-regulations&gt;&lt;etops&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="940" PostTypeId="2" ParentId="923" CreationDate="2014-01-12T08:34:27.560" Score="10" Body="&lt;p&gt;Display of ownship's position has a very strong effect on the mental model that the pilot has of it's navigation. When the EFB displayed position is wrong, the change that the pilot will detect that by comparing to other instruments or outside visual are very limited. This is a safety concern. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To have the EFB approved to display ownship's position, the most straightforward way would have been to certify it under TSO C129a &quot;Airborne Supplemental Navigation Equipment using the Global Positioning System (GPS)&quot; TSO-C129a has now been superseded by TSO-C196 which has slightly different requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often class I or class II EFB will have a GPS receiver that technically could be used as the source of ownship's position. The GPS receivers chips used in are not designed and certified against the &lt;em&gt;&quot;Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS)”&lt;/em&gt; (RTCA document DO-208), which is a requirement of TSO-C129a or &lt;em&gt;&quot;Minimum Operational Performance Standards for Global Positioning System/Aircraft Base Augmentation System&quot;&lt;/em&gt; (RTCA document DO-316) which is a requirement for TSO-C196.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major technical difference between simple commercially available GPS chips and aviation grade GPS chips is that the latter include a Receiver Autonomous Integrity Monitoring (RAIM) function which does Fault Detection (and Exclusion).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a GPS satellite would drift out of it's orbit or GPS data gets corrupted in the receiver, an ordinary GPS chip would most likely display a position error, while an aviation GPS chip would either indicate a failure state (fault detection) or still display the correct position (fault exclusion). This protects the pilot from being mislead by a map shift. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-12T08:34:27.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="941" PostTypeId="2" ParentId="829" CreationDate="2014-01-12T11:14:51.447" Score="0" Body="&lt;p&gt;I know that the Supermarine company painstakingly blind riveted the leading edge of the spitfire wing as it proved faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They did a series of experiments some involving gluing split peas in rows to mimic domed rivets!&lt;/p&gt;&#xA;" OwnerUserId="570" LastActivityDate="2014-01-12T11:14:51.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="942" PostTypeId="2" ParentId="829" CreationDate="2014-01-12T11:29:30.687" Score="1" Body="&lt;p&gt;The worst thing is a perfect flat surface, as you get a bond of static air to the surface. The flowing air has to pull away from this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best I have seen is when the wing surface has millions of small features which make the air turbulent - this is all on a macro scale at the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above flowing air rides over the turbulent air more freely.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like a stack of steel plate on thousands of ball bearings. Imagine taking the bearings away and trying to slide the steel across the floor!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sharks do this, their skin has details which stop the flowing water sticking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way is the repel the air molecules at atomic level from the wing surface - reduces sticking.   You use a high voltage electrode on leading edge to charge the air&#xA;So the wing and the air now share like charges and repel each other - less sticking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thx for the opportunity to share odd memories of random facts from decades ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have ran out of skill now and will probably not bother you again,, Steve&lt;/p&gt;&#xA;" OwnerUserId="571" LastActivityDate="2014-01-12T11:29:30.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="945" PostTypeId="5" CreationDate="2014-01-12T16:43:18.853" Score="0" Body="&lt;p&gt;The Transportation Security Administration is an agency of the US Department of Homeland Security in charge of transportation security.  They are most notable for being in charge of airport security.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions with the TSA tag should be about TSA regulations or procedures&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For additional information, see:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The TSA Webpage: &lt;a href=&quot;http://www.tsa.gov&quot; rel=&quot;nofollow&quot;&gt;http://www.tsa.gov&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Transportation_Security_Administration&quot; rel=&quot;nofollow&quot;&gt;TSA (Wikipedia)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-12T18:21:24.093" LastActivityDate="2014-01-12T18:21:24.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="946" PostTypeId="4" CreationDate="2014-01-12T16:43:18.853" Score="0" Body="The Transportation Security Administration is an agency of the US Department of Homeland Security in charge of transportation security.  They are most notable for being in charge of airport security." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-12T18:21:29.440" LastActivityDate="2014-01-12T18:21:29.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="947" PostTypeId="2" ParentId="931" CreationDate="2014-01-12T17:48:36.177" Score="13" Body="&lt;p&gt;Another consideration is the fact that the center of gravity changes as the fuel burns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet another is whether you have ballast fuel, fuel used to bring the zero fuel weight c.g. within the allowable envelope. Technically speaking, ballast fuel is not available to burn, although obviously if that's all that's left you're going to use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's the matter of extra fuel to make a captain happy that's above what the flight planned fuel is. Let's say the captain wants 8,000 lbs of extra fuel. For the old 747-100 and -200 aircraft, the rule of thumb was that if you loaded extra fuel, 20% of that fuel would be used just to carry it. In other words, If you wanted an extra 8,000 pounds available, you needed to load 10,000 extra.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another rule of thumb for the old 747s that was used as a check on whether the fuel called for in the flight plan was reasonable, was to figure 30,000 lbs burns for the first two hours, 25,000 lbs per hour after the first two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately I no longer have the manuals for the 747 that would allow me to accurately compare, say, a four hour flight against an eight hour flight.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-10-14T21:05:37.663" LastActivityDate="2014-10-14T21:05:37.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="948" PostTypeId="1" AcceptedAnswerId="950" CreationDate="2014-01-12T17:51:53.843" Score="11" ViewCount="7558" Body="&lt;p&gt;I just heard it somewhere but I'm not sure about it.   If it is, then why don't they build airtight fuselages?&lt;/p&gt;&#xA;" OwnerUserId="574" LastEditorUserId="97" LastEditDate="2014-01-28T17:36:54.400" LastActivityDate="2014-11-06T22:06:22.883" Title="Is constant air pressure maintained inside the fuselage?" Tags="&lt;aircraft-design&gt;&lt;cabin-pressure&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="949" PostTypeId="2" ParentId="888" CreationDate="2014-01-12T17:57:59.663" Score="15" Body="&lt;p&gt;The one time that I was struck by lightning for sure (there with a couple of other times I wondered if I had) was in a Cessna 310. Everything was working after the strike. However, an inspection of the airplane afterward showed that the very aft end of the right tip tank had melted and then resolidified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, a lightning charge typically &quot;flows&quot; around the outside of a metal aircraft.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-01-12T17:57:59.663" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="950" PostTypeId="2" ParentId="948" CreationDate="2014-01-12T18:02:20.997" Score="14" Body="&lt;p&gt;For the purposes of air pressure inside aircraft, they are broken down into two broad categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Unpressurized - These aircraft are typically piston powered and can't go very high, so do not even attempt to regulate the air pressure inside the fuselage.&lt;/li&gt;&#xA;&lt;li&gt;Pressurized - These aircraft do maintain pressurization in the fuselage, but it isn't constant beyond a certain point.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The category determines the answer to your question:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Unpressurized Aircraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Unpressurized aircraft are not built air-tight for a couple of reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is very hard to make something as large as an airplane truly air-tight, and keep it that way.  Over time, seals will start to leak, fittings will loosen, etc.&lt;/li&gt;&#xA;&lt;li&gt;The fuselage would have to be much stronger to withstand the pressure difference between the inside and the outside.  This would make them heavier and more expensive.&lt;/li&gt;&#xA;&lt;li&gt;There isn't much need.  These airplanes don't fly high enough to really require a pressurized fuselage and a person can breathe more or less normally even though you aren't at sea level.  (Think of people that live on mountains.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Pressurized Aircraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Without going into the details of &lt;strong&gt;how&lt;/strong&gt; an aircraft is pressurized (which isn't really relevant to your question), the air pressure inside the fuselage of a pressurized aircraft is usually maintained at sea level pressure up to a certain point.  However, the fuselage is designed to withstand a particular maximum differential air pressure, so in order to protect it (basically keep it from &quot;popping&quot; when the air pressure outside the airplane drops too low), the pressure is allowed to decrease when needed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In typical jet airplanes, the pressure inside portions of the airplane (typically the passenger compartment, some of the cargo holds, and maybe an avionics bay) at cruising altitude is maintained at a pressure which corresponds to an outside air pressure at an altitude of about 5,000 - 8,000 feet (referred to as &quot;&lt;a href=&quot;http://www.skybrary.aero/index.php/Cabin_Altitude&quot; rel=&quot;nofollow&quot;&gt;cab&lt;/a&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cabin_pressurization#Cabin_altitude&quot; rel=&quot;nofollow&quot;&gt;in&lt;/a&gt; &lt;a href=&quot;http://www.boeing.com/boeing/commercial/cabinair/environmentfacts.page&quot; rel=&quot;nofollow&quot;&gt;alt&lt;/a&gt;&lt;a href=&quot;http://www.who.int/ith/mode_of_travel/cab/en/&quot; rel=&quot;nofollow&quot;&gt;itude&lt;/a&gt;&quot;), depending on the cruising altitude and the design of the airplane.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-11-06T22:06:22.883" LastActivityDate="2014-11-06T22:06:22.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="951" PostTypeId="2" ParentId="948" CreationDate="2014-01-12T18:17:36.877" Score="2" Body="&lt;p&gt;In many General Aviation aircraft (small planes that don't go above approximately 12,000 ft.), the air pressure in the fuselage is the same as the outside air.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most people have no difficulties at altitudes up to 12,000 ft, so there is no need to maintain a pressurized environment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specific rules state that unpressurized airplanes have supplemental oxygen available, depending on how high the plane is, for how long, and whether its flying during the day or night.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-12T18:17:36.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="952" PostTypeId="1" CreationDate="2014-01-12T19:08:33.693" Score="8" ViewCount="1305" Body="&lt;p&gt;I need to replace two fuel senders in each wing of a Socata TB20, and a replacement is almost $500.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wanted to know whether a shop exists in the US that reconditions these?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some research, I'm still not sure if reconditioning resistive fuel senders is common practice at all. I only heard anecdotically about it&lt;/p&gt;&#xA;" OwnerUserId="576" LastEditorUserId="69" LastEditDate="2014-01-13T12:49:08.957" LastActivityDate="2015-06-11T21:41:56.540" Title="Can resistive fuel senders/transducers be repaired/reconditioned?" Tags="&lt;usa&gt;&lt;aircraft-maintenance&gt;&lt;fuel&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="953" PostTypeId="2" ParentId="948" CreationDate="2014-01-12T19:41:32.947" Score="12" Body="&lt;p&gt;Many aircraft are not pressurized and therefore not airtight. The occupants would suffocate, if nothing else, and most unpressurized aircraft do not regularly operate at altitudes requiring pressurization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of &lt;a href=&quot;http://en.wikipedia.org/wiki/Cabin_pressurization&quot;&gt;pressurized aircraft&lt;/a&gt;, it's actually &lt;strong&gt;necessary&lt;/strong&gt; that the cabin is &lt;strong&gt;not airtight&lt;/strong&gt;. They are, instead, &lt;em&gt;nearly airtight&lt;/em&gt; and can withstand significant pressure differentials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin pressurization works by bleeding high-pressure air from the engines, which is then run through packs (heat exchangers and &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_cycle_machine&quot;&gt;air cycle machines&lt;/a&gt;) to cool it. After conditioning, the air is fed into the cabin. This is what creates the lower cabin altitude relative to the outside atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because more air is &lt;em&gt;constantly&lt;/em&gt; being added to the fuselage, a pressure outflow valve is required &lt;strong&gt;&lt;em&gt;and it is constantly dumping air from inside the aircraft&lt;/em&gt;&lt;/strong&gt;. In normal operations, it's automatically controlled, but can be manually overridden in emergency situations.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-12T20:50:53.503" LastActivityDate="2014-01-12T20:50:53.503" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="954" PostTypeId="2" ParentId="948" CreationDate="2014-01-12T20:26:44.130" Score="3" Body="&lt;p&gt;The answers so far have talked about the differences between pressurized and unpressurized airplanes, however to answer your question why they're not &lt;em&gt;airtight&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is two-fold, first as egid pointed out, the pressure differential would probably be too great for the hull to withstand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, and in my opinion, more importantly, humans consume oxygen and output carbon dioxide (and water). Having your ship airtight, would cause everyone inside to slowly but surely suffocate from carbon dioxide poisoning and lack of oxygen as the little oxygen carried within the aircraft slowly gets breathed away. So you need to keep replacing that air, and the easiest way to do that is to let the old air out, and put new air in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Dan Pichelman points out, people in Subs aren't dropping like flies. True, they're not, but they are in fact also replacing the air. Almost. They're removing the CO2 (using Scrubbers) and adding Oxygen (from oxygen tanks). It would probably be possible to solve it this way for aircraft as well. The question remains whether it is feasible weight wise, and if it's easier to just pressurize the aircraft using bleed air and dump the old air overboard.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-01-12T21:27:45.627" LastActivityDate="2014-01-12T21:27:45.627" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="955" PostTypeId="1" CreationDate="2014-01-12T20:44:11.890" Score="6" ViewCount="1384" Body="&lt;p&gt;Our Cessna 172P is equipped with a digital CO-meter rather than the traditional Quantum eye carbon monoxide detector.&#xA;Today I was flying along in winter conditions, and naturally used cabin heat. During the flight, I heard some occasional short beeps, and couldn't figure out what it was. I looked at the CO-meter which has a red alarm light, but that light was definitely off. &#xA;On the ground, after shutting down the engine, I heard another short beep, and it definitely came from the CO-meter! The digital readout was showing 10ppm.&#xA;During post-flight, with the door open, the readout dropped to 0 ppm.&#xA;I routinely check the CO-meter battery during preflight, so I'm pretty sure the beep is not a reminder for a dead battery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to these sources: &lt;a href=&quot;http://www.coheadquarters.com/ZerotoMillion1.htm&quot;&gt;http://www.coheadquarters.com/ZerotoMillion1.htm&lt;/a&gt; , &lt;a href=&quot;http://library.thinkquest.org/10121/textonly/exposure.htm&quot;&gt;http://library.thinkquest.org/10121/textonly/exposure.htm&lt;/a&gt; and wikipedia 10ppm is nothing to be concerned about with exposure over a two-hour flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone else have a digital CO-meter and can tell if a reading of 10ppm is normal with cabin heat?&#xA;Or should I be concerned our exhaust or heat exchanger is faulty?&lt;/p&gt;&#xA;" OwnerUserId="577" LastActivityDate="2014-12-25T17:59:10.023" Title="CO-meter indicates 10ppm of Carbon Monoxide when I turn on Cabin heat - should I be concerned?" Tags="&lt;safety&gt;&lt;piston-engine&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="956" PostTypeId="1" AcceptedAnswerId="960" CreationDate="2014-01-12T21:02:30.540" Score="16" ViewCount="38289" Body="&lt;p&gt;Does an aircraft use its engines to taxi or is it always pulled by some other vehicle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen a small lorry pulling it sometimes; is it really pulling the huge thing, or does the aircraft use its own power somehow?&lt;/p&gt;&#xA;" OwnerUserId="574" LastEditorUserId="97" LastEditDate="2014-01-28T17:37:07.057" LastActivityDate="2017-02-20T15:38:08.133" Title="How does an aircraft taxi?" Tags="&lt;airport&gt;&lt;taxiing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="957" PostTypeId="2" ParentId="956" CreationDate="2014-01-12T21:04:32.567" Score="17" Body="&lt;p&gt;Usually an aircraft taxies under its own power. Aircraft have no powered wheels, so the forward thrust comes from the engines. Only pushback from the gate is mostly done by a tractor, although some aircraft can use reverse thrust for that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft is being moved for maintenance purposes or simply relocation at the airfield, the aircraft is usually pulled. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Research is going on into fitting electro motors into aircraft wheels so that they can taxi without having to start the engines. Lufthansa has done some &lt;a href=&quot;http://www.youtube.com/watch?v=au_5lSwYjig&quot;&gt;experiments&lt;/a&gt;. The concept would save taxi fuel and is more friendly to the airport environment (noise, polution), however the additional weight of the motor drive system would offset these benefits because it causes additional fuel burn during flight.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="524" LastEditDate="2014-08-12T18:22:53.207" LastActivityDate="2014-08-12T18:22:53.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="958" PostTypeId="5" CreationDate="2014-01-12T21:05:34.440" Score="0" Body="&lt;p&gt;Aircraft performance covers areas such as the amount of runway required to takeoff or land and how fast an airplane can climb or descend.  It is a very important aspect of flight planning that needs to be evaluated before every flight. &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Use this tag for:&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;General questions about how performance numbers are calculated&lt;/li&gt;&#xA;&lt;li&gt;Questions about how performance is affected by various factors (temperature, wind, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Questions about specific aircraft performance (how much runway does xxx use for takeoff)&lt;/li&gt;&#xA;&lt;li&gt;Questions comparing the performance of different types of aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-13T00:09:56.073" LastActivityDate="2014-01-13T00:09:56.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="959" PostTypeId="4" CreationDate="2014-01-12T21:05:34.440" Score="0" Body="Aircraft performance covers areas such as the amount of runway required to takeoff or land and how fast an airplane can climb or descend.  " OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-13T00:47:53.280" LastActivityDate="2014-01-13T00:47:53.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="960" PostTypeId="2" ParentId="956" CreationDate="2014-01-12T21:11:40.840" Score="22" Body="&lt;p&gt;Aircraft are not always moved with &lt;a href=&quot;http://en.wikipedia.org/wiki/Pushback&quot;&gt;tugs&lt;/a&gt; (the small vehicle you refer to). Much of the time, they operate under their own power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners are generally pushed back from the gate using a tug, as that's the simplest and most efficient method. They then taxi to the runway (and all the way up to the gate, after landing) using their own engines to provide thrust. This is true of both jets and propeller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some work is being done on self-contained electric-powered ground propulsion; one major player in this area is a company called &lt;a href=&quot;http://en.wikipedia.org/wiki/WheelTug&quot;&gt;WheelTug&lt;/a&gt;. They use high-torque motors and the aircraft APU to allow the aircraft to move itself without starting its engines or requiring a tug to be connected and disconnected.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="3172" LastEditDate="2014-08-12T17:38:08.043" LastActivityDate="2014-08-12T17:38:08.043" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="961" PostTypeId="2" ParentId="956" CreationDate="2014-01-12T21:39:32.600" Score="6" Body="&lt;p&gt;Most aircraft taxi using their own engine power. Tugs are usually only used to get an aircraft to a safe distance away from all structures, people, and other aircraft before engine start, or if the engine(s) are inoperable (maintenance, mothballing, etc.). However, there is a system (called the ElectricGreen Taxiing System, introduced at the 2013 Paris Air Show) that attaches to the wheel and uses an electric motor to move instead of the main engine(s). It is currently only available on the Airbus A320 family and the Boeing 737 family. &lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2014-01-12T21:39:32.600" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="962" PostTypeId="2" ParentId="948" CreationDate="2014-01-12T21:39:41.430" Score="4" Body="&lt;p&gt;Pressurized aircraft are not airtight, and neither are they constant pressure.  One key facet that would make being airtight impossible is the need to change pressure in the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To change pressure in the cabin, air is pumped in via the packs (covered in another answer), and air is let out via outflow valves.  The input is fairly constant flow and pressurization is modulated by how open/closed the outflow valve is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin pressure must change because the airframe has a maximum pressure differential between the cabin and outside (7.8 PSI in the EMB-145) and as you climb the pressure in the cabin must be reduced.  The cabin is generally 8000 ft pressure altitude at during cruise.  Subsequently the cabin pressure is increased to the landing airport during descent.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accompanying these changes in pressure are temperature changes naturally occurring as result of the pressure change (see: ideal gas law).  You may notice this during descents in regional jets as they tend to get very warm as the cabin is compressed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To regulate the temperature, you need air conditioning, and so you have packs and air cycle machines to deliver air at the proper temperature to the cabin.  Now that you have to provide air into the cabin, its not worth even thinking about CO2 scrubbers and O2 tanks, because the packs take care of that with fresh air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That should cover airplanes not being airtight, why they aren't airtight and that the also are not constant pressure.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-12T21:39:41.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="963" PostTypeId="1" AcceptedAnswerId="965" CreationDate="2014-01-12T21:47:13.433" Score="5" ViewCount="878" Body="&lt;p&gt;I'm just wondering because the wing isn't fixed, but they aren't rotary-wings either.&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="97" LastEditDate="2014-01-28T17:37:53.483" LastActivityDate="2014-01-28T17:37:53.483" Title="Do Grumman F-14s, Panavia Tornados, and other swing-wing airplanes count as &quot;fixed-wing aircraft?&quot;" Tags="&lt;wing&gt;&lt;jet&gt;&lt;fixed-wing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="964" PostTypeId="2" ParentId="489" CreationDate="2014-01-12T21:52:36.330" Score="0" Body="&lt;p&gt;Do not even think about it unless you are an expert. I read about an incident in Sport Aviation in which a non-aerobatic performer rolled a piston twin. The airframe was overstressed and it broke up in flight. All four on board were killed.&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2014-01-12T21:52:36.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="965" PostTypeId="2" ParentId="963" CreationDate="2014-01-12T22:04:58.330" Score="10" Body="&lt;p&gt;Yes - they are still considered fixed wing aircraft. Just because they have variable-sweep sections doesn't change what type of aircraft they are; their aerodynamics, behavior, and performance characteristics are still squarely in the 'fixed wing' category.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-12T22:04:58.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="966" PostTypeId="1" AcceptedAnswerId="967" CreationDate="2014-01-12T22:34:27.777" Score="16" ViewCount="2085" Body="&lt;p&gt;I've heard this term used to describe approaches into low weather (e.g. category 2 ILS), what is it?  How is this different than an ILS approach?  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="72" LastEditDate="2014-03-03T05:31:43.367" LastActivityDate="2017-01-28T09:48:48.350" Title="What is a monitored approach?" Tags="&lt;iaps&gt;&lt;instrument-flight-rules&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="967" PostTypeId="2" ParentId="966" CreationDate="2014-01-12T22:34:27.777" Score="19" Body="&lt;p&gt;A monitored approach is a special kind of instrument approach involving added verbal call outs and increased monitoring of the airplane and is typically conducted when weather is below a certain threshold. For example, a crew may be required to fly a monitored approach if the weather is below 3/4 mile vis and the captain has less than 100 hours in type, or in any case with the weather below ILS Category I minimums. It is also specific to multi-crew aircraft and requires at least 2 pilots and in many cases an autopilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a crew environment, the pilots are typically designated as Pilot Flying (PF) and Pilot Not Flying (PNF).  In general the PF is flying and making commands of the PNF, and the PNF mans the radios and operates gear and flaps the command of the PF.  More detail of this setup probably deserves its own question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate a monitored approach, I'll describe on based on my companies procedures.  The specific requirements can vary between operators based on crew training, aircraft equipment and approved opspecs.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;The monitored approach briefing&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;We have identified the arrival airport current weather is 1200 RVR and obscured ceilings and we plan to fly the ILS to category II minimums.  Myself and my first officer have both have current category 2 training, neither of us are high-minimums, and the aircraft has no MEL items effecting category 2 operations.  We are legal to fly the approach, but company operations require we fly it as a monitored approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of who has been PF and PNF up to this point, the first officer becomes the PF and the captain the PNF.  The PF briefs the approach as normal except for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CAT II radar altitude minimums&lt;/li&gt;&#xA;&lt;li&gt;Low vis taxi routes if applicable&lt;/li&gt;&#xA;&lt;li&gt;The approach will be flown by the autopilot (company specific)&lt;/li&gt;&#xA;&lt;li&gt;Special autopilot considerations&lt;/li&gt;&#xA;&lt;li&gt;Required verbal call outs (see below)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;The monitored approach&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;For my company, the autopilot had to be engaged in &quot;CAT 2&quot; mode before glideslope intercept.  This will vary by aircraft and company.  For the approach, as noted earlier, the first officer is PF, captain is PNF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PF duties are to monitor the autopilot and to execute the missed approach if the autopilot has problems.  The PNF also monitors the autopilot.  The pilots are monitoring the autopilot for performance and for indications it cannot meet required tolerances for the approach.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF will call for gear and flaps as normal, except a non standard flap setting may be used for the approach (e.g. we flew flaps 22 instead of 45).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once configured for landing, the PF will call for &quot;Landing checklist - to the line&quot; (company specific), this for us was the normal landing checklist with the caveat that the checklist is complete when the captain announces &quot;Landing, I have the airplane&quot; (more on this in a moment).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nearing the Cat II decision height (typically 100 ft RA), the PNF will announce &quot;Going heads up&quot;, discontinue monitoring the autopilot and look for the approach lighting system and the runway lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PF will continue to monitor the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane will announce &quot;Minimums&quot; at the radar altitude DH and when the airplane reaches this height, the PNF will fly the missed approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the captain sees the required lighting to continue the approach, they will announce &quot;Landing, I have the airplane&quot;, and the FO will reply &quot;you have the airplane, landing checklist complete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Captain must disconnect the autopilot (by 50 feet, no autoland for us), and would fly any aborted landing executed after taking control.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Caveats&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Rules on autopilot usage, disconnect heights and autolanding will vary based on aircraft and company policies.  My example assumes an Embraer-145 certified for Cat 2 approaches and no autothrottles or autoland capability.  Checklist verbiage and flap configurations mentioned also would vary by aircraft and company.  And finally, the specific callouts will vary by company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it seems like there was a lot of Category II specific things in my example, the two concepts of reduced visibility ILS approaches and monitored approaches are intertwined, and you will almost always be flying a monitored approach because it is required to conduct the low weather approach by company policy. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-21T01:19:32.833" LastActivityDate="2014-01-21T01:19:32.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="968" PostTypeId="2" ParentId="955" CreationDate="2014-01-12T23:29:00.120" Score="10" Body="&lt;p&gt;The short answer is you should be concerned.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although 10PPM of carbon monoxide doesn't pose an immediate health risk for short term exposure the fact that the level is rising &lt;em&gt;when you turn on the cabin heat&lt;/em&gt; &amp;amp; falling when you ventilate the cabin (by opening the door) indicates you may have an exhaust leak, and those tend to get worse over time.&lt;br&gt;&#xA;You should have your shop open the heat muff &amp;amp; inspect the exhaust system for cracks/leaks before your next flight (or if that isn't possible avoid (or limit) use of cabin heat &amp;amp; defrost &amp;amp; monitor the CO meter as part of your scan until the exhaust system can be checked).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should also check your CO meter: electronic CO meters have a finite life, just like chemical spot detectors (though they generally last several years) - your detector's manual will specify a replacement interval. As the sensors age they may give inaccurate readings.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A note about ground operations - Electronic CO detectors are sensitive enough to occasionally generate transient alarms during ground operations due to exhaust gasses entering the cabin. This can happen during summer or winter.&lt;br&gt;&#xA;As long as the levels are low and the alarm clears when you're moving (taxi or during climb-out) this is probably not a problem, but you should know what is &quot;normal&quot; for your aircraft.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-12T23:29:00.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="969" PostTypeId="1" AcceptedAnswerId="971" CreationDate="2014-01-12T23:43:36.507" Score="9" ViewCount="667" Body="&lt;p&gt;Can aircraft be modified to have an enormous audio system, like the ones in cars? Has the FAA got any regulations on this (or maybe on in-cabin maximum noise volume?), would power be a limitation for the audio system?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="72" LastEditDate="2014-01-13T01:29:56.583" LastActivityDate="2014-01-13T18:57:48.470" Title="Is it possible to &quot;pimp up your aircraft&quot; with an audio system?" Tags="&lt;faa-regulations&gt;&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="970" PostTypeId="2" ParentId="955" CreationDate="2014-01-13T00:07:29.113" Score="7" Body="&lt;p&gt;Even though voretaq7's answer is correct, I just want to add that there is also a chance that the sensor is broken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should know that the sensor is made of a ceramic plate that has to be heated in order to get a readout, and then it is cooled down again. Also it has to be calibrated before using, to get an absolute measurement instead of a relative measurement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you ever left the sensor in a very cold/wet or very hot place? Or did you leave it in the aircraft on the ground during a sunny day? The ceramic plate can easily be damaged by exposing it to the conditions mentioned above. You might want to test it in another plane and if it still shows the same output, the chances are high that the sensor is broken.&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="3504" LastEditDate="2014-12-25T17:59:10.023" LastActivityDate="2014-12-25T17:59:10.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="971" PostTypeId="2" ParentId="969" CreationDate="2014-01-13T00:12:52.790" Score="4" Body="&lt;p&gt;Absolutely not, as it would not be in the sense of security.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It would block engine sounds (eg you won't be able to hear a rough engine)&lt;/li&gt;&#xA;&lt;li&gt;It would block warning sounds, for example stall warnings&lt;/li&gt;&#xA;&lt;li&gt;It would block any other abnormal sounds&lt;/li&gt;&#xA;&lt;li&gt;You will have problems understanding ATC (and they will have even more problems understanding you)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are just some reasons out of my head. If you want to listen to music inflight, buy a good headset with an AUX-In socket, those normally reduce the volume as soon as a transmission is incoming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And apart from the audio volume, it would also put a high load on the battery / alternator, which are probably not able to handle such a high load.&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="213" LastEditDate="2014-01-13T11:08:00.130" LastActivityDate="2014-01-13T11:08:00.130" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="972" PostTypeId="1" AcceptedAnswerId="974" CreationDate="2014-01-13T00:43:39.293" Score="5" ViewCount="1056" Body="&lt;p&gt;What is the policy for ATC towers to notify aircraft the frequency they broadcast and monitor on has changed? How do they do it, if radio isn't available (because they just changed their frequency)?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="97" LastEditDate="2014-03-21T04:03:40.500" LastActivityDate="2021-04-07T21:42:34.753" Title="How should a Traffic Control Tower notify aircraft that their frequency just changed?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="973" PostTypeId="1" AcceptedAnswerId="976" CreationDate="2014-01-13T00:49:46.190" Score="11" ViewCount="3832" Body="&lt;p&gt;I heard that the FAA recently changed how they calculate the protected area for circling approaches, and it looked quite complicated because it changes based on altitude and speed, etc.  Can you please explain how you know when to use the old -vs- new criteria, what distance you can safely use, and how to figure it out quickly when flying?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="72" LastEditDate="2014-03-03T07:45:43.203" LastActivityDate="2014-03-03T07:45:43.203" Title="When conducting a circling approach, how close do you have to stay to the airport (especially with the new FAA requirements)?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;airspace&gt;&lt;iaps&gt;&lt;circling-approach&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="974" PostTypeId="2" ParentId="972" CreationDate="2014-01-13T00:53:01.627" Score="13" Body="&lt;p&gt;ATC frequencies don't change very often, but when they do they are planned well in advance.  NOTAM's are issued ahead of time to let people know, and if the airport has ATIS they will include the new frequency on the ATIS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is an enroute frequency, the other controllers will simply hand you off to the new frequency, and you don't even need to know about it ahead of time.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-13T00:53:01.627" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="975" PostTypeId="2" ParentId="972" CreationDate="2014-01-13T01:01:54.923" Score="8" Body="&lt;p&gt;A Notice to Airmen (NOTAM) will be issued for the airport pending a charting change.  If you subscribe to a charting service like Jeppesen, you will get a change notice from them and updated approach plates with the new frequency.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-13T01:01:54.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="976" PostTypeId="2" ParentId="973" CreationDate="2014-01-13T02:08:45.633" Score="5" Body="&lt;p&gt;The protected area for circling approaches is based on distance from the runway(s), and the size of that area (and your approach MDA) depends upon your aircraft's VREF or 1.3&amp;times;V&lt;sub&gt;SO&lt;/sub&gt; — or, if higher, your actual IAS approach speed. Here's the graphic the FAA uses to demonstrate this, along with the old protected area radii:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kE5b7m.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;New circling minumums&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;For approaches that use the new criteria, both Aeronav and Jeppesen charts show an inverted &quot;&lt;strong&gt;C&lt;/strong&gt;&quot; in the circling minimums section of the approach plate. This signifies that the approach uses the new, altitude-dependent protected areas. Those areas are defined in the same way as before, but with different radii.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Aeronav (NACO) format:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TZpSJ.jpg&quot; alt=&quot;Aeronav&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Jeppesen format:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wi3sJ.jpg&quot; alt=&quot;Jeppesen&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as figuring out how large your protected area is in flight, you'll have to use the inverted &quot;&lt;strong&gt;C&lt;/strong&gt;&quot; as a cue to look up the table that will be included in the appendices of the approach plates:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aeronav.faa.gov/d-tpp/1401/frntmatter.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mfDA1.png&quot; alt=&quot;New minimums table&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NBAA has &lt;a href=&quot;http://www.nbaa.org/ops/airspace/issues/20130418-faa-expands-size-of-protected-airspace-for-circling-approaches.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;a more detailed description of the changes&lt;/a&gt;, but this basically sums it up.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The update leaves us with what is honestly a less-than-desirable system. Looking up a table to brief your circling radius in flight (or even prior to your flight) is certainly a lot less useful than simply printing the protected area radius on the minimums section. It's worth noting that feature &lt;a href=&quot;http://aeronav.faa.gov/content/aeronav/acfstatus/RDs/09-01-213_TERPS_Chg21_Circling_Appr.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;was proposed in 2009&lt;/a&gt; (p. 4) when the change was being discussed.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-13T16:26:49.307" LastActivityDate="2014-01-13T16:26:49.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="977" PostTypeId="5" CreationDate="2014-01-13T02:58:25.030" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-13T02:58:25.030" LastActivityDate="2014-01-13T02:58:25.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="978" PostTypeId="4" CreationDate="2014-01-13T02:58:25.030" Score="0" Body="Questions relating to the costs of owning, renting or flying a plane, etc." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-13T03:12:24.790" LastActivityDate="2014-01-13T03:12:24.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="979" PostTypeId="5" CreationDate="2014-01-13T02:59:49.287" Score="0" Body="&lt;p&gt;Aircraft maintenance refers to the routine (and not-so-routine) work required to keep an aircraft in an operable and airworthy condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft maintenance questions can include questions about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Work performed by aircraft maintenance technicians, mechanics, and repair shops&lt;/strong&gt;&lt;br&gt;&#xA;Things like as pitot-static system tests, annual inspections, and engine overhauls)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Specialty shop work&lt;/strong&gt;&lt;br&gt;&#xA;Interior refits and aircraft painting&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Preventive maintenance&lt;/strong&gt;&lt;br&gt;&#xA;Typically items covered under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.21&amp;amp;idno=14#14:1.0.1.3.21.0.363.14.53&quot; rel=&quot;nofollow&quot;&gt;FAR 43 Appendix A&lt;/a&gt; and can be performed by a mechanic or a certificated pilot under 91&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Authorized owner-performed maintenance&lt;/strong&gt;&lt;br&gt;&#xA;Such as what can be done on a Light-Sport aircraft with a repairman's certificate,  an experimental aircraft by the builder, or &lt;a href=&quot;http://www.copanational.org/AircraftInCaOwnerMaint.cfm&quot; rel=&quot;nofollow&quot;&gt;work on a Canadian aircraft registered as &quot;Owner Maintenance&quot;&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1961" LastEditDate="2015-04-09T06:31:43.743" LastActivityDate="2015-04-09T06:31:43.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="980" PostTypeId="4" CreationDate="2014-01-13T02:59:49.287" Score="0" Body="Use this tag for questions pertaining to the maintenance of aircraft, including owner-performed maintenance and required inspections (annual, 100-hour, etc.)" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-14T23:07:01.607" LastActivityDate="2014-01-14T23:07:01.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="981" PostTypeId="5" CreationDate="2014-01-13T04:16:58.203" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-13T04:16:58.203" LastActivityDate="2014-01-13T04:16:58.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="982" PostTypeId="4" CreationDate="2014-01-13T04:16:58.203" Score="0" Body="Currency refers to recency of experience that may be required by aviation authorities in order to operate an aircraft." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-13T04:32:24.370" LastActivityDate="2014-01-13T04:32:24.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="984" PostTypeId="1" CreationDate="2014-01-13T08:40:51.877" Score="4" ViewCount="298" Body="&lt;p&gt;Typically, a pilot will have airplane insurance (or renter's insurance, if flying un-owned aircraft), car insurance, home insurance, life insurance and then for good measure purchase an &quot;umbrella&quot;-type insurance (usually up to $1MM). Have there been cases where this wasn't enough insurance, or the pilot thought he or she was insured but there was something unforeseen that rendered his insurance policies ineffective of shielding him or her from liability?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is specific towards American pilots, in this case if would be for an &quot;average&quot; person, owning/flying a small single-engine piston airplane and a net worth of less than $1MM.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="69" LastEditDate="2014-01-13T12:52:38.957" LastActivityDate="2014-08-07T00:10:39.987" Title="Are there any pitfalls to be wary of when purchasing an &quot;umbrella&quot; insurance policy?" Tags="&lt;usa&gt;&lt;liability&gt;&lt;insurance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="985" PostTypeId="1" AcceptedAnswerId="995" CreationDate="2014-01-13T08:49:26.543" Score="9" ViewCount="2031" Body="&lt;p&gt;We've been having some discussions around if there was a specific ruling from the FAA that explicitly said that if a cylinder was showing less than 60 on the compression test, the FAA deemed it unairworthy.  I've heard that, it's a rule-of-thumb and not a ruling, but I don't know for sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has this been conclusively made into a ruling from the FAA, or does it exist as a rule-of-thumb and there are other factors to consider?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be specific to United States/FAA and 4-6 cylinder Lycoming or Continental piston engines.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="19" LastEditDate="2017-03-27T08:21:27.627" LastActivityDate="2017-03-27T08:21:27.627" Title="Is there an FAA ruling about the airworthiness of piston engines with less than 60 on the compression test?" Tags="&lt;faa-regulations&gt;&lt;piston-engine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="986" PostTypeId="1" AcceptedAnswerId="989" CreationDate="2014-01-13T08:55:43.183" Score="25" ViewCount="1659" Body="&lt;p&gt;Have there been any studies that gathered statistics on overlooked items on preflight inspections, or even statistics on how many pilots actually perform a good preflight (following a checklist, etc.)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If such a study exists, did it uncover anything that proved to be something that was often overlooked?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an industry &quot;best practices&quot; document for preflight inspections (beyond just following the manufacturer's checklist found in the POH)?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="65" LastEditDate="2015-04-15T17:49:16.803" LastActivityDate="2017-12-28T12:59:03.900" Title="What is the most overlooked item during preflight inspection?" Tags="&lt;safety&gt;&lt;preflight&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="987" PostTypeId="5" CreationDate="2014-01-13T12:41:20.707" Score="0" Body="&lt;p&gt;The &lt;strong&gt;Boeing 737&lt;/strong&gt; is a narrowbody twinjet airliner produced by &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt;, which first flew in 1967 and was introduced into commercial service with &lt;a href=&quot;/questions/tagged/lufthansa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lufthansa&amp;#39;&quot; rel=&quot;tag&quot;&gt;lufthansa&lt;/a&gt; in February 1968.  It has been continuously in production ever since then, and is the best-selling commercial jetliner in history, with the 10,000th 737 coming off the assembly line in March 2018.  The 737, in all its various iterations, is also, since the last of the &lt;a href=&quot;/questions/tagged/dc-9-family&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-9-family&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-9-family&lt;/a&gt; (the DC-9-95, marketed as the Boeing 717) left production in April 2006, Boeing's only narrowbody airliner still in production (and the only Boeing-&lt;em&gt;designed&lt;/em&gt; narrowbody produced since &lt;a href=&quot;/questions/tagged/boeing-757&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-757&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-757&lt;/a&gt; production ceased in October 2004); Boeing's other three currently-produced airliners, the &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;, are all widebody (twin-aisle) aircraft.  The 737's primary competition is from the &lt;a href=&quot;/questions/tagged/airbus-a320&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a320&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a320&lt;/a&gt; family of jetliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 has had a total of thirteen passenger variants throughout its history (plus several military or business-jet versions), falling into four families:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The original-series 737 (the 737-100 and 737-200), with a total of 1,125 produced from 1965 through 1988; these are easily distinguishable by their use of low-&lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt; Pratt &amp;amp; Whitney JT8D &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt; engines, unlike all newer 737s.  Due to their higher noise levels and fuel consumption compared to later models, few 737-200s remain in service, and none of the smaller 737-100.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 737 Classic series (the 737-300, -400, and -500), with a total of 1,988 produced from 1984 until 2000; these are larger (except for the 737-500) than the original 737s, and feature various aerodynamic enhancements, but most of the original 737's design was, nevertheless, inherited intact (including a hitherto-unforeseen design defect in the 737's system of &lt;a href=&quot;/questions/tagged/flight-controls&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-controls&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-controls&lt;/a&gt; which could cause the &lt;a href=&quot;/questions/tagged/rudder&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rudder&amp;#39;&quot; rel=&quot;tag&quot;&gt;rudder&lt;/a&gt; to jam in the fully-deflected position).  They are also the first 737s to use a high-bypass turbofan, the CFM International (GE/SNECMA)&lt;sup&gt;1&lt;/sup&gt; CFM56; due to the limited space available underneath the 737's wings, various engine components were moved from the bottom of the engine to the sides, giving the engine nacelles of all CFM56-powered 737s a highly-distinctive &quot;hamster-pouch&quot; shape.  The new engines produce much less noise than those on the 737-100 and -200, and are more fuel-efficient; this, combined with the improved aerodynamics, gives Classic 737s a considerably greater range than the original series.  However, they still burn more fuel and have a shorter range than the newer families of 737, and, as such, are being slowly replaced by 737s from these newer families (although there are still many Classic 737s in service throughout the world).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;The 737 Next Generation (NG) series (the 737-600, -700, -800, and -900), with 7,092 produced from 1996 through 2019; these feature a larger, more efficient wing, greater fuel capacity, and a newer, more efficient variant of the CFM56 engine, all of which combine to give them greater range yet than previous 737 models.  The 737 NGs are also the first 737s to use a modern &quot;glass cockpit&quot;, with primarily electronic displays rather than mechanical gauges and dials, and the largest Next Generation 737s are a further step up in passenger capacity than the 737s that came before.&lt;/li&gt;&#xA;&lt;li&gt;The 737 MAX series (the 737 MAX 7, MAX 8, MAX 200 [officially MAX 8200], and MAX 9, with another variant, the MAX 10, under development), with 387 having been produced and delivered since 2016 and over 4,500 more orders pending; these incorporate various aerodynamic tweaks (including a distinctive split-tip winglet) compared to the 737 NG series, plus an updated cabin interior, but their most visible change is the use of a new, more efficient engine, the CFM International LEAP.  The LEAP is larger than the CFM56, necessitating larger and longer landing gear for the 737 MAX compared to all prior 737s (and allowing for the elimination of the hamster-pouch nacelle design), and its engine nacelles incorporate noise-reducing chevrons similar to those first seen on the &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;.  The 737 MAX series includes both the largest (737 MAX 9, soon to be displaced by the 737 MAX 10) and longest-range (737 MAX 7) 737s yet.  Since March 2019, the 737 MAX series has been temporarily grounded pending a fix for a new flight-control bug (this time involving the &lt;a href=&quot;/questions/tagged/mcas&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;mcas&amp;#39;&quot; rel=&quot;tag&quot;&gt;mcas&lt;/a&gt; system, used to slightly improve the aircraft's handling characteristics in certain high-&lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt; flight regimes); as of January 2020, test flights are in progress, but passenger service has not yet resumed.  737 MAX production was temporarily paused starting in January 2020, with full-scale production to resume as soon as the aircraft is cleared to return to service.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The 737 may, at some point in the future, be replaced by a &quot;New Midsize Airplane&quot; (NMA); however, the NMA might well turn out to be yet another family of 737s (as happened with the 737 MAX series).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To learn more, see Wikipedia's articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 737 overall, plus information specific to the Original series&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Classic&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 737 Classic&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_rudder_issues&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Original / Classic's flight-control bugs&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 737 Next Generation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 737 MAX&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX_groundings&quot; rel=&quot;nofollow noreferrer&quot;&gt;the MAX's flight control bugs&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_New_Midsize_Airplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;the New Midsize Airplane&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: SNECMA was renamed to &quot;Safran&quot; in 2016.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2020-01-07T08:56:22.347" LastActivityDate="2020-01-07T08:56:22.347" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="988" PostTypeId="4" CreationDate="2014-01-13T12:41:20.707" Score="0" Body="A short- to medium-range twinjet narrow-body airliner, originally introduced in 1968. &#xD;&#xA;With over 10,500 aircraft delivered and over 4500 on order, the Boeing 737 is the most popular commercial jetliner in history. " OwnerUserId="19" LastEditorUserId="22726" LastEditDate="2020-01-07T07:41:41.573" LastActivityDate="2020-01-07T07:41:41.573" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="989" PostTypeId="2" ParentId="986" CreationDate="2014-01-13T14:24:30.597" Score="21" Body="&lt;p&gt;This FAA &lt;a href=&quot;http://lessonslearned.faa.gov/Northwest255/E_Checklists.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; is about using electronic checklists for airline flights (it concludes that they're better than paper ones) and includes this quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;They found the crews averaged 3.2 checklist errors per flight (one of&#xA;  the observed flights had 14.) The most-common checklist error involved&#xA;  the omission or deferral of an item, which was later forgotten.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;NASA commissioned a &lt;a href=&quot;http://ti.arc.nasa.gov/m/profile/adegani/Cockpit%20Checklists.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;general study&lt;/a&gt; into checklists in 1990, but it doesn't identify specific items that are commonly overlooked. It does say that as the number of items on a checklist increases, the chances of overlooking any individual one does too:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Swain and Guttman (1983), in their study of nuclear power plant&#xA;  operations “recognized the fact that as the list of items grows, there&#xA;  may be a higher probability of overlooking any given item” (chap. 15,&#xA;  p. 13)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The final section of the paper has recommendations for checklist design, which could be considered the &quot;best practices&quot; you mentioned, but of course it's a very general list, e.g.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The most critical items on the task-checklist should be listed as&#xA;  close as possible to the beginning of the task-checklist, in order to&#xA;  increase the likelihood of completing the item before interruptions may occur&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;AOPA's Flight Training magazine has an &lt;a href=&quot;https://web.archive.org/web/20151222033956/http://flighttraining.aopa.org/magazine/2006/February/200602_Features_Unlucky_13.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; on &quot;frequently forgotten&quot; checks that is more specific and most of the checks seem to apply to most (light) aircraft, but it doesn't provide any authoritative sources. They also have a &quot;how to preflight&quot; &lt;a href=&quot;https://web.archive.org/web/20140316204425/http://flighttraining.aopa.org/students/presolo/skills/howtopreflight.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; that gives more information and includes this interesting observation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As an experiment, I held a preflight contest with a &quot;bugged&quot; trainer.&#xA;  I reversed the rigging on the ailerons so their movement was contrary&#xA;  to control inputs. Every one of the contestants checked control&#xA;  movement and freedom, but no one caught the problem.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Putting all that together suggests - only to me, and I'm not an expert - that it's less important to think about specific items that you might forget, and more important to ensure that you complete the checklist fully and really verify the results of each check. If you consider some checklist items to be 'more important' than others then it could also lead to mistakes because you overlook the 'less important' ones.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="753" LastEditDate="2017-12-28T12:59:03.900" LastActivityDate="2017-12-28T12:59:03.900" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="990" PostTypeId="2" ParentId="808" CreationDate="2014-01-13T14:37:35.320" Score="10" Body="&lt;p&gt;I am not aware of any legal limitation for air trafic controllers to speak out on a public website, but there could be one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;StuckMic.com is however an ATC forum in which FAA ATCo's seem to participate actively. This leads me to believe that they are allowed to speak out on a public website. There are very likely restrictions on what they can share.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-13T14:37:35.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="991" PostTypeId="1" AcceptedAnswerId="992" CreationDate="2014-01-13T14:42:23.570" Score="11" ViewCount="3550" Body="&lt;p&gt;If you fly low, air is dense so you can get more thrust from your engines, but you get more drag.&lt;br&gt;&#xA;On the other hand if you fly higher you have less drag but the output of engine decreases as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what's the optimum altitude to fly at, and how does one determine it?&lt;/p&gt;&#xA;" OwnerUserId="574" LastEditorUserId="64" LastEditDate="2014-01-13T18:36:50.940" LastActivityDate="2019-06-02T16:07:33.127" Title="How do I determine the best altitude to fly for fuel economy?" Tags="&lt;weather&gt;&lt;aircraft-performance&gt;&lt;density-altitude&gt;&lt;fuel&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="992" PostTypeId="2" ParentId="991" CreationDate="2014-01-13T15:03:25.793" Score="13" Body="&lt;p&gt;The optimum altitude depends on your aircraft, the engines and the weather. But most important is to decide what you are trying to achieve. If you would like to optimize your fuel consumption per distance travelled, the altitude you will fly at will be higher than if you try to optimize your fuel consumption per time unit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel per distance travelled is usually better at altitude, while fuel flow per time unit is lower at lower altitudes. In other words, if you want to go far, fly high. If you want to keep flying long, fly low. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winds play an important role as well. If you have a strong headwind high up, you might go further staying low. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is quite some difference between reciprocating engines and jet / turbine engines here. The former perform better at lower altitudes, while the latter do just fine until much higher. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-13T15:03:25.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="993" PostTypeId="2" ParentId="991" CreationDate="2014-01-13T15:09:27.643" Score="3" Body="&lt;p&gt;Another factor in the decision to fly low or high: turbulence.  How important is it to you and your passengers to have a smooth ride?  Higher is generally less turbulent but check those Airmets and Pireps!&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-13T15:09:27.643" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="994" PostTypeId="2" ParentId="952" CreationDate="2014-01-13T15:28:37.233" Score="4" Body="&lt;p&gt;While I have no personal experience with refurbished or reconditioned fuel senders, I did some research, and there &lt;a href=&quot;http://goo.gl/iK4JYM&quot; rel=&quot;nofollow&quot;&gt;do appear to be shops&lt;/a&gt; that will work on aviation units. An &lt;a href=&quot;http://goo.gl/Hb3K0S&quot; rel=&quot;nofollow&quot;&gt;alternate search&lt;/a&gt; has some different results. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These results imply that that it is both legal to recondition fuel senders, and that there are a few options within the US.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the record, I wasn't able to track down a manufacturer or part number for the units used by SOCATA, which makes it a bit more difficult to research. I do know that Cessna senders can be found for &lt;a href=&quot;http://www.mcfarlane-aviation.com/SearchResults.aspx?ID=99806010&amp;amp;SearchType=Keyword&amp;amp;Search=fuel%20sender&amp;amp;&quot; rel=&quot;nofollow&quot;&gt;under $300&lt;/a&gt; at McFarlane, if that gives you a price comparison, or in case one of those is the right unit. &lt;a href=&quot;http://www.aircraftspruce.com/menus/ep/fuelsender.html&quot; rel=&quot;nofollow&quot;&gt;Aircraft Spruce&lt;/a&gt; has even cheaper units (Rochester and Westach) but I'm not sure why they are &lt;em&gt;so cheap&lt;/em&gt;; often the parts Spruce carries are not for certified aircraft, but that doesn't seem to be the case. Either option is certainly cheaper than the price SOCATA seems to have quoted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck with your search, and if you find a shop or a part number, make sure to update (or comment on) your question!&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-13T15:28:37.233" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="995" PostTypeId="2" ParentId="985" CreationDate="2014-01-13T15:34:14.100" Score="11" Body="&lt;p&gt;Long story short is that the manufacturers instructions take precedence over all. &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/appendix-D_to_part_43&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR Part 43 Appendix D&lt;/a&gt; requires that at each annual and 100 hr the compression be checked and that if there is &quot;weak&quot; compression further inspection of condition and tolerances of the engine have to be made. Now the term &quot;weak&quot; is kind of broad. &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99861&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Advisory Circular AC43.13-1B&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a cylinder has less than a 60/80 reading on the differential test gauges on a hot engine, and procedures in paragraphs 8-14b(5)(i) and (j) fail to raise the compression reading, the cylinder must be removed and inspected.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However&lt;/strong&gt;, it also states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This advisory circular (AC) contains methods, techniques, and practices acceptable to the Administrator for the inspection and repair of nonpressurized areas of civil aircraft, only when there are no manufacturer repair or maintenance instructions. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the gist of it seems to be that if the compression is below 60/80 on a hot engine IN GENERAL, then yes it needs to be removed and inspected, UNLESS the manufacturers instructions state otherwise. Keep in mind Advisory Circulars are guidelines and not regulatory in nature although they are usually used as best practice guides. There is a great AVweb article &lt;a href=&quot;http://www.avweb.com/news/savvyaviator/188758-1.html?redirected=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Savvy Aviator #13: Putting Compression In Context&lt;/a&gt; that has more in depth analysis. &lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="19" LastEditDate="2017-03-27T08:11:45.997" LastActivityDate="2017-03-27T08:11:45.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="996" PostTypeId="2" ParentId="939" CreationDate="2014-01-13T18:23:57.290" Score="5" Body="&lt;p&gt;On the great circle route from Sydney to Santiago, from southern New Zealand (past Invercargill, maybe) to southern Chile, there is a stretch of about 4,000 nm with no landing sites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are specific requirements for air carriers for &quot;extended overwater operations.&quot; These take into account the aircraft range after engine failure, distance to diversion airports, emergency equipment and training, etc. There is definitely a backup plan in place for every overwater airline flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A twin engine jet airliner will have an ETOPS (&lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;Extended range Twin Operations&lt;/a&gt;) rating that is the distance it able to reliably fly, fully loaded, on one engine. Many Boeing 777s have an ETOPS rating of 330 minutes, for example, which means they must fly on a route that keeps them within 5.5 hours of an airport at single engine speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners conducting extended overwater operations must be ditching certified, which involves aircraft design, emergency equipment, and crew training for emergency water landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fInn0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="396" LastEditDate="2014-01-14T08:04:07.520" LastActivityDate="2014-01-14T08:04:07.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="997" PostTypeId="2" ParentId="969" CreationDate="2014-01-13T18:57:48.470" Score="9" Body="&lt;p&gt;While there are &lt;a href=&quot;https://aviation.stackexchange.com/a/971/64&quot;&gt;many great reasons not to do this&lt;/a&gt; it would seem from a cursory scan of the FARs that the answer is &quot;Yes, you can.&quot; -- At least one company (&lt;a href=&quot;http://www.altoaviation.com/prod_aes.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alto Aviation&lt;/a&gt;) is producing aircraft entertainment systems with relatively &quot;pimped out&quot; audio capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These systems seem more geared toward &quot;cabin class&quot; aircraft where the crew and passenger compartments are separated (mainly business twin/turboprop/jet aircraft), though I suppose you could conceivably install it in something like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-32&quot; rel=&quot;nofollow noreferrer&quot;&gt;PA-32&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_206&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 206&lt;/a&gt;, or even light piston singles if you wanted to.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such an installation would be subject to the same restrictions as any electrical device installation (requiring a check to ensure it doesn't overload the electrical system, and verification that it won't interfere with navigation or communication equipment), and I would imagine some of the work required may qualify as a &quot;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ec3a64d9ccc48e67394097874cd6eb61&amp;amp;node=14:1.0.1.3.21.0.363.14.53&amp;amp;rgn=div9&quot; rel=&quot;nofollow noreferrer&quot;&gt;major alteration&lt;/a&gt;&quot; as a change to the &quot;basic design of the electrical system&quot; may be involved.&lt;br&gt;&#xA;There may also be additional operating restrictions placed on the installed equipment (like &quot;Not permitted for use during taxi, takeoff, or landing&quot; to prevent it from being a distraction/safety hazard during critical phases of flight).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-01-13T18:57:48.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="998" PostTypeId="2" ParentId="984" CreationDate="2014-01-13T19:08:11.203" Score="3" Body="&lt;p&gt;An umbrella policy is insurance on top of insurance in case your primary insurance is not enough. For this reason it is usually inexpensive relative to to other insurance policies. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using your example, a million dollars beyond what you are already insured for is a pretty good amount of coverage. It would take a really catastrophic event for a small plane to do more than a million dollars worth of damage beyond the limits of an owner's or renter's insurance policy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're considering an umbrella policy be sure that it does not specifically exclude aircraft because many do. If you purchase a policy through an agent who knows that you are a pilot, you're probably fine but don't assume that your commercial umbrella policy covers you because many commercial umbrella polices specifically exclude aircraft.&lt;br&gt;&#xA;I would be more worried about the umbrella policy excluding aircraft (like you mentioned unforeseen things rendering the policy ineffective in the last sentence of the first paragraph) rather than a million dollars on top the normal coverage not being enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also assuming that by typical pilot you mean small aircraft not a corporate jet or something that has a lot more potential liability.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="64" LastEditDate="2014-01-13T19:16:46.930" LastActivityDate="2014-01-13T19:16:46.930" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="999" PostTypeId="1" AcceptedAnswerId="1009" CreationDate="2014-01-13T19:50:24.597" Score="18" ViewCount="11409" Body="&lt;p&gt;I've been flying Cessna 172 &amp;amp; 182's my whole flying life up to this point.  I know that Cirruses (Cirri?) have a &quot;side yoke&quot; and Diamonds, Citabrias and others have control sticks coming up through the seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this a design difference or are there actual functional differences between airplanes that have control yokes (like Cessna 182's) or sticks (like Diamonds) or side yokes (like Cirrus)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I realize that with the side yoke offers more legroom perhaps, but are there reasons beyond that - like pull/push force required?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="65" LastEditDate="2015-04-15T17:47:35.190" LastActivityDate="2019-08-25T14:51:04.307" Title="What are design or functional differences between sticks and yokes?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1000" PostTypeId="1" AcceptedAnswerId="1005" CreationDate="2014-01-13T19:54:15.770" Score="15" ViewCount="4324" Body="&lt;p&gt;I often hear a spec of the &quot;roll-rate&quot; when talking about aerobatic airplanes and the term &quot;fast ailerons.&quot; What exactly does that mean, and what makes the ailerons on an aerobatic airplane different than the ailerons on a non-aerobatic airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the design of the ailerons affect the roll-rate of the airplane?&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2018-03-18T01:48:21.397" Title="What makes the ailerons on an aerobatic airplane different than the ailerons on a non-aerobatic airplane?" Tags="&lt;aircraft-design&gt;&lt;aerobatics&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1001" PostTypeId="1" AcceptedAnswerId="1004" CreationDate="2014-01-13T19:57:26.317" Score="14" ViewCount="7326" Body="&lt;p&gt;I've seen airplanes (typically Cessna 172s) with a &quot;Powerflow&quot; exhaust system and then claim to get several more horsepower, resulting in faster cruise speeds.  How does a Powerflow exhaust work, and why does it increase horsepower?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="64" LastEditDate="2014-01-14T23:03:17.033" LastActivityDate="2021-01-05T03:09:11.047" Title="Why/How does a &quot;Powerflow&quot; exhaust increase horsepower?" Tags="&lt;piston-engine&gt;&lt;aircraft-performance&gt;&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1002" PostTypeId="2" ParentId="952" CreationDate="2014-01-13T20:05:29.550" Score="5" Body="&lt;p&gt;There are shops that do this and &lt;a href=&quot;https://aviation.stackexchange.com/a/994/64&quot;&gt;egid gave you a couple of hints on how to find one&lt;/a&gt;, but your local mechanic can probably recondition your fuel sender about as well as any of the specialty shops, as long as they're not squeamish about opening up the unit (and as long as the unit &lt;em&gt;can&lt;/em&gt; be opened up - I'm not sure about the TB20 senders).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's basically involved is cleaning the resistor element and wiper contacts, making sure everything is making good contact through its full range of travel, and verifying that the sender is still within a reasonable calibration range when you're done with the cleaning (you can use your other, working sender to determine what's &quot;reasonable&quot;, or verify using your fuel gauge).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://documents.clubexpress.com/documents.ashx?key=2npcOElrLayHk46cCBko651s%2B08N0D%2F2WajwHsh%2BIKIlnDrHciiU%2BgyP2ydKyEVSTG4ELLO3fSU3niq5MlkUYg%3D%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Comanche folks have a nice article on reconditioning a (really beat up) fuel sender&lt;/a&gt;, and technologically they're similar to automotive fuel senders, so &lt;a href=&quot;http://documents.clubexpress.com/documents.ashx?key=2npcOElrLayHk46cCBko651s%2B08N0D%2F2WajwHsh%2BIKIlnDrHciiU%2BgyP2ydKyEVSTG4ELLO3fSU3niq5MlkUYg%3D%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article about reconditioning Corvette fuel senders&lt;/a&gt; may also be useful to get an idea of what you're in for.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-01-13T20:05:29.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1003" PostTypeId="2" ParentId="1001" CreationDate="2014-01-13T20:32:27.417" Score="11" Body="&lt;p&gt;Powerflow exhaust systems are based on the principle that an engine is, essentially, a large noisy air pump: air is drawn in through the intake, and pumped out the exhaust.&lt;br&gt;&#xA;A limiting factor on how much horsepower an engine produces is how quickly you can move a given volume of air through the engine (because of restrictions in either the intake or exhaust system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft, like Cessna 172s or 140/150/160 horsepower Piper Cherokees, have an exhaust system that restricts how quickly exhaust gasses can be &quot;pumped out&quot;, due to unfavorable geometry, narrow pipe sizes, or both. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Powerflow systems, like &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Tuned_exhaust&quot;&gt;tuned exhaust&lt;/a&gt;&quot; systems you find on sports cars, provide a wide pipe and a geometry that encourages pulling as much of the exhaust gas out of the cylinder as possible, which means less energy is wasted pushing the piston up during the exhaust stroke, and more oxygen-rich air will be pulled into the cylinder during the subsequent intake stroke - both contributing to producing more usable horsepower.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-13T20:32:27.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1004" PostTypeId="2" ParentId="1001" CreationDate="2014-01-13T20:34:05.257" Score="16" Body="&lt;p&gt;It has to do with resonance.  Think of a pipe organ - each pipe resonates at a certain frequency, which we hear as a note or tone.  The length of the pipe determines its note/tone/resonance frequency.  Your plane's exhaust system has a certain resonance frequency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your plane's engine has a certain note or tone, too.  That is largely determined by engine RPM.  A powerflow exhaust matches the exhaust resonance frequency with the engine's rpm at a typical high cruise setting.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a micro level, here is what happens.  After a cylinder's power stroke, when the exhaust valve first opens, exhaust floods out into the exhaust system.  Soon the exhaust valve shuts and the inertia of the gasses moving down the exhaust system cause the exhaust gas to continue towards the exit, creating a lower pressure behind it (near the exhaust valve).  If the resonance frequency of the exhaust system matches the rpm, at that point the exhaust valve opens on the next cycle, and the lower pressure area in the exhaust assists in scavenging the exhaust out of the cylinder.  On the subsequent intake stroke, there is less residual pressure in the cylinder and it can &quot;suck in&quot; more fuel/air mixture.  More fuel/air, more power.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to say this is that it takes power for the engine to force the exhaust out of the cylinder and through the exhaust system.  The Powerflow system reduces the power required to do this.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-13T20:56:00.590" LastActivityDate="2014-01-13T20:56:00.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1005" PostTypeId="2" ParentId="1000" CreationDate="2014-01-13T20:45:20.163" Score="12" Body="&lt;p&gt;The term &quot;fast ailerons&quot; is an informal term that generally refers to the response of the plane relative to the pilot's input to the aileron controls on the stick or yolk. The faster the plane responds, the faster the ailerons (or other controls).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The roll rate is the speed at which a plane can complete a roll. This depends on a number of factors, including aileron size, maximum aileron deflection, wing length, and speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ailerons that can deflect a lot of air without disrupting the airflow over the wing too much are desirable in an aerobatic plane, so the roll rate can be increased and so the plane will have better roll control at lower speeds. While larger ailerons are desirable on an aerobatic plane, they are also more susceptible to flutter at high speeds, which is not desirable because it tends to rip them off the wing. There are several design techniques that can be used to mitigate this, such as gap seals, counterweights, countersurfaces, etc.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-01-13T20:45:20.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1006" PostTypeId="2" ParentId="999" CreationDate="2014-01-13T21:05:03.377" Score="-2" Body="&lt;p&gt;I think you will not find side yokes (side sticks) on older aircraft that have purely mechanical connections to the control surfaces.  Sometimes they require both pilot and copilot to shove on the controls to get the desired result.  Look at how robust the controls are on a DC-3 for example.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the force required, it is merely a design issue.  Potato, Potatoe.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-13T21:05:03.377" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="1007" PostTypeId="1" AcceptedAnswerId="1039" CreationDate="2014-01-13T21:17:43.970" Score="13" ViewCount="1313" Body="&lt;p&gt;When I learned to fly helicopters, I of course spent significant time learning about and practicing autorotations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CFI at my school, who had around 15,000 hrs (that's right, fifteen thousand!) said a few times that practice, knowledge and currency are vital &amp;mdash; but as long as you got the entry right (following which you can fly to the ground) and executed at least a decent attempt at the flare and cushion, you would survive. Is this a correct take on the survivability of an autorotation? &lt;strong&gt;Do fatalities arise primarily from errors during the autorotation entry or flare?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you might not get to use the machine again, and you might spend some time in hospital, you would live to fly another day.  I am assuming a reasonable place on dry land is available to finally come to rest and no post-crash fire.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1696" LastEditDate="2015-03-02T20:14:15.927" LastActivityDate="2015-03-02T20:14:15.927" Title="Will occupants usually survive a decent autorotation?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1008" PostTypeId="1" AcceptedAnswerId="1010" CreationDate="2014-01-13T21:36:52.893" Score="10" ViewCount="25511" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/A380&quot;&gt;Wikipedia&lt;/a&gt; provides some numbers (typical empty weight, MTOW, max fuel capacity, etc.), but I can't seem to find more detailed figures. For a purpose of this question, let's assume a fully loaded A380 in typical 3-class configuration (~530 passengers) and fuel for a long haul flight (&gt;10h).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what is the typical weight of the passengers + luggages? Is any additional cargo typically carried? If so how much? What about the weight of crew and catering? And fuel weight? (Fuel weight will depend on actual flight duration, so the answer should mention the corresponding flight duration.)&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="97" LastEditDate="2014-01-13T22:23:50.227" LastActivityDate="2014-04-18T03:34:59.380" Title="What is the weight budget of a fully loaded A380?" Tags="&lt;weight-and-balance&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1009" PostTypeId="2" ParentId="999" CreationDate="2014-01-13T22:05:46.710" Score="20" Body="&lt;p&gt;There is some link between the type of control and the design maneuverability of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a yoke.  Imagine twisting it to bank.  You are moving it with a twisting motion of one or both arms and in general, aircraft fitted with such yokes are capable of low to moderate roll rates.  Big displacements are uncommon but small, rapid, alternating changes are common.  Watch a wide body PF making control movements during a landing with any kind of xwind or turbulence.  They are less sensitive and give more visual feedback as to the control positions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider a stick, central to the pilot flying.  This is moved with a movement of the arm, generally only one, and can be rapidly displaced easily.  This is normally associated with aircraft with high rates of roll, especially in an aircraft designed to rapidly null out or reverse the roll.   It is also physically easier to move a stick than a yoke under high-G as the arm movement gives a longer lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A great example of this was the Vulcan which, despite its size, enormous wing area and large fin, was so rollable that it could out-maneuver the interceptors of its day.  It has a control column rather than a yoke and the PF would throw it around at altitude as if it were a fighter.  This would not be easy to do with a yoke.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a bit long in the tooth and haven't flown fixed wing for many years.  I am not familiar with the rationale behind side sticks which are fitted to both low and high performance aircraft.  I am guessing they are fitted more for reasons of ergonomics than for performance.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="753" LastEditDate="2019-08-25T14:51:04.307" LastActivityDate="2019-08-25T14:51:04.307" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="1010" PostTypeId="2" ParentId="1008" CreationDate="2014-01-13T23:35:06.867" Score="10" Body="&lt;p&gt;These weights are all based on the maximum an aircraft will ever see. The maximum allowed weight of passengers (+luggage) and cargo (called payload weight) is the difference between the &lt;strong&gt;Operational empty weight&lt;/strong&gt; (about 270,000 kg) and the &lt;strong&gt;Zero fuel weight&lt;/strong&gt; (361,000 kg). This means the payload weight is about 91,000 kg. The passenger and crew weight can be estimated by the following numbers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;175 lbs per pax + 30 lbs of baggage for short medium range distance (or 40 lbs for long range)&lt;/li&gt;&#xA;&lt;li&gt;175 lbs per crew member + 30 lbs of baggage$^1$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So let's say that (for easier calculations) the average passenger + luggage weight is 100 kg.&#xA;When we assume 530 passengers and 25 crew, then the weight would be $555\times100=55,000kg$. That leaves 36,000 kg for cargo.&#xA;All the weights listed are, of course, maximum weights. That means that an aircraft in general does not meet these values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum fuel weight is the difference between &lt;strong&gt;maximum ramp weight&lt;/strong&gt; and &lt;strong&gt;zero fuel weight&lt;/strong&gt; (which is $562,000-361,000=201,000kg$). About 2,000 kg is taken for the time the engines are running while the aircraft did not yet take of (for taxiing etc). This is the difference between maximum ramp weight and MTOW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of fuel varies so much per flight that I really can't say anything about it. It depends on the air pressure in the flight path (aircraft choose their routes depending on that, for a faster flight), weather along the route, and much more. For quite a good overview I suggest for you to read &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_planning#Fuel_calculation&quot; rel=&quot;nofollow&quot;&gt;this Wikipedia page&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope I answered your question sufficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$^1$ Source: Jan Roskam, Airplane design, Part I: Preliminary Sizing of Airplanes (1985)&lt;/p&gt;&#xA;" OwnerUserId="598" LastEditorUserId="97" LastEditDate="2014-04-18T03:34:59.380" LastActivityDate="2014-04-18T03:34:59.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1012" PostTypeId="1" AcceptedAnswerId="1014" CreationDate="2014-01-14T01:30:28.637" Score="10" ViewCount="30465" Body="&lt;p&gt;I am kind of stuck for calculating a descent path on the ILS RWY 7 approach into &lt;a href=&quot;http://www.airnav.com/airport/KORL&quot; rel=&quot;nofollow noreferrer&quot;&gt;KORL&lt;/a&gt;. Assuming the glide slope is not available and you have to use the localizer only, what is the best way to calculate the descent and Decision to Land Point?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1glEV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1glEV.png&quot; alt=&quot;ILS or LOC RWY 7 KORL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in the approach chart, the MDA is 660 feet for the localizer only approach. Assuming a glide path of 3°, I calculated a descent of 318 feet per Nautical Mile. However, that would not correlate to the 1919 feet at the Outer Marker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would be the best way to calculate / plan the approach in this example?&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="14897" LastEditDate="2016-08-20T18:20:02.737" LastActivityDate="2016-08-20T18:20:02.737" Title="How to calculate the vertical profile for a LOC only approach?" Tags="&lt;iaps&gt;&lt;instrument-flight-rules&gt;&lt;localizer&gt;&lt;non-precision-approach&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1013" PostTypeId="2" ParentId="1012" CreationDate="2014-01-14T01:58:19.053" Score="2" Body="&lt;p&gt;Ignore the 1919 glideslope intercept at the OM, as that is for an ILS approach only. For the LOC approach, in Cat A, you will cross the FAF at 2000 and descend to the 660ft MDA over the next 5.5nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are (at least) two ways to plan and fly a non precision approach. You can just try to descend constant from the FAF to the MAP, hoping you reach the MDA and maybe being in a position to land. The alternative is to reach the MDA early, prior to the MAP, ensuring that you spend at least some time at the actual approach minimums. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;constant rate to threshold&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For a constant descent rate to the MAP, you should divide the altitude to descend (FAF minus MDA) by the distance to travel. In this case, that's (2000 - 660)/5.5, or 243 feet per nautical mile. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;early descent to MDA&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There is no published VDP, so I'll assume a self-determined point 1.0nm from the MAP; this means you must descend at 330 feet per nm:  (2000-660)/4.5. At 90 knots that is around 450 fpm, which is about what I'd expect for a non precision approach. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as a decision-to-land point goes, that depends on the aircraft and your personal minimums more than something I can calculate. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-14T02:09:29.273" LastActivityDate="2014-01-14T02:09:29.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1014" PostTypeId="2" ParentId="1012" CreationDate="2014-01-14T02:14:28.353" Score="5" Body="&lt;p&gt;The approach shows that the glideslope (if it were working) is a three degree descent angle.   You can calculate your own visual descent point (VDP), since one isn't provided for you, by taking the height above touchdown (600 ft. in this case) and dividing it by 300 ft/NM.  This gives you 2.0 miles from the runway.  Since the chart shows the runway threshold at 0.2 DME, your VDP will be at 2.2 DME.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that your navigation equipment does not provide a pseudo-glideslope, your best bet is to descend at your normal rate (in a light airplane I would say 800-900 fpm) until you level at 660 ft. (the MDA), then fly to your calculated VDP (2.2 DME) and if you have the required visual cues then descend to the runway knowing that it will be a standard 3 degree descent (300 ft./NM).  If you don't have it at this point, then you can start an early climb and fly the missed approach.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Put another way, first you calculate your VDP:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{Height~Above~Touchdown}{Descent~Rate}=VDP~Distance~From~Runway$$&#xA;$$\frac{600ft}{300 ft/NM}=2.0NM$$&#xA;$$VDP=Runway~Threshold+VDP~Distance~From~Runway$$&#xA;$$0.2DME+2.0NM=2.2 DME$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you fly the approach:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cross HERNY at 2,000 ft.&lt;/li&gt;&#xA;&lt;li&gt;Descend to minimums (660 ft.) at 800-900 fpm.&lt;/li&gt;&#xA;&lt;li&gt;Fly to 2.2 DME at 660 ft.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At 2.2 DME, if you see the runway environment, start your descent and land&lt;/li&gt;&#xA;&lt;li&gt;If you don't see the runway, start your climb and fly the published missed approach&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-17T02:35:15.627" LastActivityDate="2014-04-17T02:35:15.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1015" PostTypeId="1" AcceptedAnswerId="1016" CreationDate="2014-01-14T02:40:04.177" Score="11" ViewCount="1043" Body="&lt;p&gt;I have flown a bunch of times on a Bombardier Dash-8 Q400 on a couple of different airlines, and several times I have flown a shuttle flight that is basically empty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been instructed to change seats on these flights, reportadly to balance the plane better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears as though the request comes from the cockpit relayed back to the cabin staff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane appears to be static in place, so how do they determine that they need to balance the plane?  Does the landing gear report this sort of info?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Dash-8 is a reasonably 'large' airplane that it seems sort of surprising that the balance is so delicate that the weight of a few people can make the difference. &lt;/p&gt;&#xA;" OwnerUserId="80" LastEditorUserId="69" LastEditDate="2014-01-14T03:16:06.410" LastActivityDate="2014-01-14T03:16:06.410" Title="On a larger airplane, how do they manage balance?" Tags="&lt;weight-and-balance&gt;&lt;turboprop&gt;&lt;dash-8&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1016" PostTypeId="2" ParentId="1015" CreationDate="2014-01-14T02:47:36.170" Score="9" Body="&lt;p&gt;Before the main cabin door is closed, the ramp personnel will deliver a cargo sheet that lists&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;number of checked bags&lt;/li&gt;&#xA;&lt;li&gt;number of gate checked bags&lt;/li&gt;&#xA;&lt;li&gt;number of heavy checked bags&lt;/li&gt;&#xA;&lt;li&gt;pounds of commercial cargo&lt;/li&gt;&#xA;&lt;li&gt;pounds of company cargo&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With numbers broken down by cargo bin where accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight attendant will deliver a sheet with passenger count in zones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FMS or EICAS screens can tell you how much fuel is on board.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From there, some airline have ACARS programs that you plug those numbers into and it will give you weight information (to turn #bags and #people into pounds). Other have worksheets to calculate the weights.  In the EMB-145 we then had to spin a special wheel with the weight information to get the balance info.  This can vary by operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some operators will have the W&amp;amp;B calculated by dispatch and all of the numbers I mention above are put into the computer system by various people and the dispatcher will deliver the W&amp;amp;B and takeoff reference data to the pilots via ACARS. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;What if there is a problem?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Problems can be overweight overall, overweight in the cabin, overweight in the bag compartments or out of balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For overweight, remove people or bags as necessary.  If fuel has not arrived and you can do without some, call dispatch to revise the numbers and load less fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are out of balance, you move people or bags around.  This was rarely an issue and if it does happen you just ask a passenger from zone X to sit in zone Y for takeoff.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-14T02:55:21.493" LastActivityDate="2014-01-14T02:55:21.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1017" PostTypeId="1" AcceptedAnswerId="1114" CreationDate="2014-01-14T03:12:26.910" Score="14" ViewCount="18218" Body="&lt;p&gt;When flying an airplane that requires more than one crew member, does the SIC need to be landing current and instrument current, or is this a requirement only for the PIC?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it matter which regulations that you are operating under (Part 91, 121, or 135)?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T03:52:59.103" LastActivityDate="2019-04-11T17:57:30.030" Title="Does a Second In Command have to be landing and instrument current like a Pilot In Command does?" Tags="&lt;faa-regulations&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1019" PostTypeId="1" CreationDate="2014-01-14T03:29:18.793" Score="8" ViewCount="2282" Body="&lt;p&gt;I recently had someone ask me if there was a GPS RAIM availability calculator available for the iPad.  There isn't, but it got me thinking that I could write one.  After doing some searching, I can't find a good explanation of how to calculate RAIM availability, so am looking for the formulas used to calculate it for a specific route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want this to be an offline tool, so the calculations need to be complete, rather than relying on a website for the information. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T12:32:58.307" LastActivityDate="2014-05-02T03:58:53.627" Title="How is GPS RAIM availability calculated?" Tags="&lt;raim&gt;&lt;gnss&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1020" PostTypeId="5" CreationDate="2014-01-14T03:41:06.827" Score="0" Body="&lt;p&gt;This tag should be used for questions about how GPS works and uses of GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see: &lt;a href=&quot;http://en.wikipedia.org/wiki/Global_Positioning_System&quot; rel=&quot;nofollow&quot;&gt;GPS (Wikipedia)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T04:26:22.923" LastActivityDate="2014-01-14T04:26:22.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1021" PostTypeId="4" CreationDate="2014-01-14T03:41:06.827" Score="0" Body="Global Positioning System consists of a group of satellites that are used in conjunction with special purpose receivers to calculate a precise location.  It is often used for aircraft navigation purposes." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T04:22:50.207" LastActivityDate="2014-01-14T04:22:50.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1022" PostTypeId="5" CreationDate="2014-01-14T03:44:02.653" Score="0" Body="&lt;p&gt;RAIM is used to determine whether or not the position calculated by a GPS system is correct.  It requires one additional satellite in addition to those required to calculate the position in order to cross-check the calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see: &lt;a href=&quot;http://en.wikipedia.org/wiki/Receiver_autonomous_integrity_monitoring&quot; rel=&quot;nofollow&quot;&gt;RAIM (Wikipedia)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T04:26:33.533" LastActivityDate="2014-01-14T04:26:33.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1023" PostTypeId="4" CreationDate="2014-01-14T03:44:02.653" Score="0" Body="Receiver Autonomous Integrity Monitoring is a technology developed to assess the integrity of GPS signals in GPS receiver systems. " OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T04:22:53.363" LastActivityDate="2014-01-14T04:22:53.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1024" PostTypeId="5" CreationDate="2014-01-14T03:46:14.300" Score="0" Body="&lt;p&gt;&lt;em&gt;Non-precision&lt;/em&gt; or &lt;em&gt;nonprecision&lt;/em&gt; approaches are instrument approach procedures (&lt;a href=&quot;/questions/tagged/iaps&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;iaps&amp;#39;&quot; rel=&quot;tag&quot;&gt;iaps&lt;/a&gt;) that provide lateral guidance to the approaching aircraft (keeping its flightpath aligned with and pointed at the &lt;a href=&quot;/questions/tagged/runway&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runway&amp;#39;&quot; rel=&quot;tag&quot;&gt;runway&lt;/a&gt;), but &lt;em&gt;not&lt;/em&gt; vertical guidance (the pilot has to manually figure out how and when to descend, sometimes with the help of &lt;a href=&quot;/questions/tagged/air-traffic-control&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;air-traffic-control&amp;#39;&quot; rel=&quot;tag&quot;&gt;air-traffic-control&lt;/a&gt;).  In contrast, a &lt;a href=&quot;/questions/tagged/precision-approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;precision-approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;precision-approach&lt;/a&gt; provides both lateral &lt;em&gt;and&lt;/em&gt; vertical guidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-precision approaches, somewhat counterintuitively, are generally &lt;em&gt;harder&lt;/em&gt; to fly than precision approaches, as they place greater demands on the pilot's piloting skills (as opposed to just flying the aircraft down the tunnel in the sky and having the ILS display or the PAR controller or whatnot tell you if you're in the wrong chunk of air).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples of non-precision approaches include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/vor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vor&amp;#39;&quot; rel=&quot;tag&quot;&gt;vor&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/ndb&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ndb&amp;#39;&quot; rel=&quot;tag&quot;&gt;ndb&lt;/a&gt; approaches utilize, as the names suggest, a VOR or NDB installation on or near the airport.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/localizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;localizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;localizer&lt;/a&gt;, or LOC, approaches utilize the localizer portion of an airport's &lt;a href=&quot;/questions/tagged/ils&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ils&amp;#39;&quot; rel=&quot;tag&quot;&gt;ils&lt;/a&gt; installation; the localizer provides only lateral guidance, unlike the full ILS, but it can still be used even if the ILS's &lt;a href=&quot;/questions/tagged/glideslope&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glideslope&amp;#39;&quot; rel=&quot;tag&quot;&gt;glideslope&lt;/a&gt; is out of service.&lt;/li&gt;&#xA;&lt;li&gt;Some types of &lt;a href=&quot;/questions/tagged/rnav&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rnav&amp;#39;&quot; rel=&quot;tag&quot;&gt;rnav&lt;/a&gt; (&lt;a href=&quot;/questions/tagged/gnss&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gnss&amp;#39;&quot; rel=&quot;tag&quot;&gt;gnss&lt;/a&gt;) approaches, which use satellite navigation (GPS) to determine the aircraft's location, provide only lateral guidance, and are, thus, non-precision approaches; other types are true precision approaches, providing both lateral and vertical guidance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information, &lt;a href=&quot;http://en.wikipedia.org/wiki/Non-precision_approach#Non-precision_approaches_and_systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-08-20T10:01:49.963" LastActivityDate="2019-08-20T10:01:49.963" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1025" PostTypeId="4" CreationDate="2014-01-14T03:46:14.300" Score="0" Body="Non-precision approaches are instrument approach procedures (IAPs) that do not include vertical guidance." OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-08-18T03:11:01.147" LastActivityDate="2019-08-18T03:11:01.147" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1026" PostTypeId="5" CreationDate="2014-01-14T03:51:01.473" Score="0" Body="&lt;p&gt;A &lt;em&gt;localizer&lt;/em&gt; (or &lt;em&gt;localiser&lt;/em&gt;, if you're British) is a ground-based &lt;a href=&quot;/questions/tagged/radio-navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radio-navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;radio-navigation&lt;/a&gt; aid which provides lateral guidance to approaching aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A localizer consists of an antenna array which transmits in two narrow beams - one slightly to the left of the approach course and one slightly to the right - which use the same radio frequency, but pulse at different rates.  An aircraft's localizer receiver listens to the signal from the two beams; if the overall signal pulses at the rate of the left-of-course beam, the aircraft is too far to the left (and the pilot's &lt;a href=&quot;/questions/tagged/flight-instruments&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-instruments&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-instruments&lt;/a&gt; tell them to fly further right), and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A localizer usually forms one part of an &lt;a href=&quot;/questions/tagged/ils&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ils&amp;#39;&quot; rel=&quot;tag&quot;&gt;ils&lt;/a&gt;; however, it can usually also be used on its own, without the glideslope, to provide guidance for a &lt;a href=&quot;/questions/tagged/non-precision-approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;non-precision-approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;non-precision-approach&lt;/a&gt; (this is known as a &lt;em&gt;localizer approach&lt;/em&gt; or &lt;em&gt;localizer-only approach&lt;/em&gt;, abbreviated LOC).  There are two main types of localizer approach:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;em&gt;front-course&lt;/em&gt; localizer approach is basically an ILS approach minus the glideslope; it uses the signal emitted from (surprise surprise) the front side of the localizer array (the side that it's designed to provide the best guidance on).  Newer localizer antennae emit essentially their entire signal from the front of the array, making a front-course approach the only type possible with these localizers.&lt;/li&gt;&#xA;&lt;li&gt;Older localizers, however, can sometimes be used for a &lt;em&gt;back-course&lt;/em&gt; (or, in Europe, &lt;em&gt;back beam&lt;/em&gt;) localizer approach.  As you might have guessed from the name, this takes advantage of the fact that older designs of localizer arrays emitted significant amounts of signal in non-front directions (known as &lt;em&gt;sidelobes&lt;/em&gt;), with a major portion of this being emitted directly backwards.  Although less reliable than a front-course approach (due to the weaker signal), a back-course approach - if properly flown - is still quite safe (assuming, of course, that the localizer in question is old enough to support this kind of approach).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The vast majority of localizers are located some distance past the far ends of the runways they serve, and mark out an approach path that leads straight to, and down, the runway.  However, for some airports, terrain considerations make a straight-in approach impossible or inadvisable, and the localizer beam is, instead, at a considerable angle to the runway (and may be located a considerable distance therefrom); at a certain point in such an approach, aircraft wishing to land rather than crash must deviate from the localizer path and maneuver visually to the runway.  Such a non-aligned localizer is called a &lt;em&gt;localizer-type directional aid&lt;/em&gt; (LDA); in a few rare cases, an LDA is paired with a &lt;a href=&quot;/questions/tagged/glideslope&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glideslope&amp;#39;&quot; rel=&quot;tag&quot;&gt;glideslope&lt;/a&gt; to form an &lt;em&gt;instrument guidance system&lt;/em&gt; (IGS), an unusual subtype of ILS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see the Wikipedia articles about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system_localizer&quot; rel=&quot;nofollow noreferrer&quot;&gt;The localizer&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Localizer_type_directional_aid&quot; rel=&quot;nofollow noreferrer&quot;&gt;The LDA&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-08-22T05:47:08.157" LastActivityDate="2019-08-22T05:47:08.157" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1027" PostTypeId="4" CreationDate="2014-01-14T03:51:01.473" Score="0" Body="A localizer is a radio navigation aid used for lateral guidance by aircraft approaching an airport to land." OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-08-22T05:46:54.307" LastActivityDate="2019-08-22T05:46:54.307" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1028" PostTypeId="1" AcceptedAnswerId="1029" CreationDate="2014-01-14T04:11:33.117" Score="17" ViewCount="487" Body="&lt;p&gt;I'm considering getting a private pilot license, but considering that it is &lt;a href=&quot;https://aviation.stackexchange.com/a/211/567&quot;&gt;more dangerous than driving a car&lt;/a&gt; (with pilot error being a large factor of that), I want to make sure I train with a CFI and aircraft that are safe, and also ensure that I learn the habits necessary to become a safe pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any objective (or fairly reliable subjective) ways to determine the quality of training provided by CFI at a local flying club? &lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-01-14T08:04:28.473" Title="How can I determine the quality of training provided by a CFI at a local flying club?" Tags="&lt;flight-training&gt;&lt;ppl&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1029" PostTypeId="2" ParentId="1028" CreationDate="2014-01-14T05:16:10.567" Score="13" Body="&lt;p&gt;Jeff, I really appreciate that you ask for safety before asking for the price. Unfortunately it takes some experience and time at a school to say if the equipment and teaching methods are safe or not, but I'll try my best to provide you with some of my insights into flight training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I personally tend to the bigger flight schools. Having a strict training concept and standardized methods is a huge benefit in safety. If the same teachers also do more advanced training like IR or MEP your PPL training will most probably also be more intense. Your training should concentrate on learning to fly not flying the nicest routes but of course you should also enjoy your time. That's why you should of course also have a look at the people who are there. They should not only be friendly, but also be professional and well organised. The most annoying thing during flight training is bad organization and the changing of schedules due to absolutely avoidable reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good maintenance is key for safety. Here again, a big flight school that can do it's own maintenance has a lot of advantages. Often it happens that there are minor problems which should be fixed before the next flight without being a big safety hazard. It's better to squawk this and wait ten minutes until maintenance has fixed it, rather then flying without having it fixed, or cancelling the lesson. If the flight school has its own maintenance and they are happy with their work they will tell you and also show you around. Honestly the only thing you can do is to look if the hangar looks clean and tidy. If you decide for a smaller school without its own maintenance, it should at least be done at the same airport. Otherwise this could cause regular delays in your training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also think of yourself. During your solos and later when having your license you are allowed to and you will fly alone without an instructor. Be motivated to learn more than you have to. Know your aircraft and ask your questions. RTFM should not be the general answer of your flight school but you should spend some time doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I made a list with all my questions before visiting different flight school so I don't forget to ask them. I would sugest you to do the same before getting there. If you for example ask for some more detailed information how many flight time you have to do with an instructor before flying solo and what exercises and maybe progress checks you'll have to do prior to it, you'll get a good insight how structured the flight training is. Also don't forget to ask about the theoretical part. That's really dependent on your self if you prefer to learn with books or with a teacher in front of you.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="526" LastEditDate="2014-01-14T08:04:28.473" LastActivityDate="2014-01-14T08:04:28.473" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1030" PostTypeId="2" ParentId="999" CreationDate="2014-01-14T06:22:38.547" Score="2" Body="&lt;p&gt;I'm posting only to confirm a detail mentioned in Simon's excellent answer, since I've flown all three of the aircraft mentioned in the question (Cirrus, Cessna, Diamond), which he hasn't.&lt;/p&gt;&#xA;&lt;p&gt;The bit about side yokes, which he mentions he isn't familiar with, is completely correct.  To reiterate:&lt;/p&gt;&#xA;&lt;h3&gt;Control type ordered by ease of control input&lt;/h3&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Center stick&lt;/strong&gt; (easiest)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Side stick&lt;/strong&gt; / &lt;strong&gt;side yoke&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Standard (center) yoke&lt;/strong&gt; (least easy)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-14T06:22:38.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1031" PostTypeId="2" ParentId="1019" CreationDate="2014-01-14T07:32:31.703" Score="1" Body="&lt;p&gt;RAIM availability calculations are simply checking to see if at least 5 satellites will be visible, that's all it is.  You'll need the orbital equations to calculate that though.  It would probably be easier to pull data from one of the websites that provide RAIM information. &lt;a href=&quot;http://www.raimprediction.net&quot; rel=&quot;nofollow&quot;&gt;http://www.raimprediction.net&lt;/a&gt; is the FAA's site.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-01-14T07:32:31.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1032" PostTypeId="2" ParentId="931" CreationDate="2014-01-14T07:51:36.960" Score="7" Body="&lt;p&gt;On the 747-400, the general rule for extra fuel used to carry extra fuel was 4% per hour or 3% per hour depending on your requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you wish to arrive with 10,000 pounds extra after a 10 hour flight you would have to load 14,000 pounds extra before departure (the 4% rule)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you load 14,000 pounds extra before departure for the same 10 hour flight, this is burnt at 3% per hour (the 3% rule) leaving you with about 10,000 pounds at arrival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sums:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$10,000\times4\%\times10hours=4,000lbs~burnt$$ to carry it, so load 14,000 pounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$14,000\times3\%\times10hours=4,200lbs~burnt$$ to carry it, leaving 9,800 at the destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close enough for Government work!&lt;/p&gt;&#xA;" OwnerUserId="608" LastEditorUserId="97" LastEditDate="2014-04-18T03:14:12.100" LastActivityDate="2014-04-18T03:14:12.100" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1033" PostTypeId="2" ParentId="1019" CreationDate="2014-01-14T09:03:41.187" Score="7" Body="&lt;p&gt;The website that Ralgha points out is indeed the one to look at for the US. They also provide a SOAP interface should you want to create your own app for the IPAD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For RAIM to be available, you need to check firstly that at least 5 satellites (Space Vehicles in GPS language) are visible from you position, or 4 if your RAIM algorithm uses Baro-aiding. They have to be well above the horizon. How much depends on your satellite receiver, the FAA uses 5 degrees on their website. There are some receivers that use a masking angle of only 3 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orbital equations can be taken from the &lt;a href=&quot;http://www.gps.gov/technical/icwg/IS-GPS-200G.pdf&quot;&gt;GPS interface control document&lt;/a&gt;, section 30.3.3.1.3. They take &lt;a href=&quot;http://navcen.uscg.gov/?Do=gpsArchives&amp;amp;path=ALMANACS/YUMA&amp;amp;year=2014&amp;amp;exten=txt&quot;&gt;almanac data&lt;/a&gt; as input. Apart from the Space Vehicle orbits, you also need to take into account their health from the &lt;a href=&quot;http://navcen.uscg.gov/?Do=constellationStatus&quot;&gt;NANU's&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the satellites available, you need to calculate the RAIM containment bound. This is the maximum size that a position error can grow due to a faulty satellite signal without the RAIM algorithm noticing it within 10 seconds (with a 99.9% probability). If that containment bound is more than 1 nautical mile, RAIM is said to be unavailable for terminal procedures. For NPA a 0.3 nautical mile radius is used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The containment bound depends very much on the geometry of the satellites, more that on the number of satellites available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with the RAIM algorithms is that they aren't standardized. There are several ways to perform RAIM and because GPS manufacturers use proprietary solutions there is little information available to the public. So calculating the containment bound is where you will get stuck. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there is no easy way to implement RAIM prediction on an IPad, apart from using the FAA website. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Europe has also a RAIM prediction website; &lt;a href=&quot;http://augur.ecacnav.com/&quot;&gt;AUGUR&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-14T09:03:41.187" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1034" PostTypeId="2" ParentId="279" CreationDate="2014-01-14T10:52:05.473" Score="4" Body="&lt;p&gt;Not really an answer per-se, but I usually find it much easier to learn what NOT to read-back:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Weather information (except QNH (altimeter settings)), like wind speed/direction, etc&lt;/li&gt;&#xA;&lt;li&gt;Time/hour/estimates (except EAT (expected approach time) when cleared to a hold)&lt;/li&gt;&#xA;&lt;li&gt;Chatter (hey, it happens! don't read it back)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can't seem to think to any others, though there should be a couple more. Anything else that doesn't fall into this will get a readback from me. &lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-01-14T22:37:19.800" LastActivityDate="2014-01-14T22:37:19.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1035" PostTypeId="1" AcceptedAnswerId="1037" CreationDate="2014-01-14T11:11:07.260" Score="27" ViewCount="4671" Body="&lt;p&gt;Apparently, even if you have declared an urgent situation or an emergency, you cannot enter restricted or prohibited airspace, and ATC may not be able to clear you into the area. So, my question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you had a serious condition onboard an aircraft (say severe icing) and high terrain (I know, you probably haven't planned) in all directions except for restricted or prohibited airspace, what should you do to try and make sure that people are aware of your situation and can try and minimise the risk of doing so?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="69" LastEditDate="2014-01-14T18:28:25.573" LastActivityDate="2015-07-01T22:20:44.090" Title="What should you do if you are forced to enter restricted or prohibited airspace?" Tags="&lt;airspace&gt;&lt;emergency&gt;&lt;special-use-airspace&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1037" PostTypeId="2" ParentId="1035" CreationDate="2014-01-14T13:05:44.930" Score="26" Body="&lt;p&gt;Even if ATC can't legally give you permission to enter prohibited airspace (they &lt;em&gt;sometimes&lt;/em&gt; can for restricted airspace by the way), if you declare an emergency they will still coordinate with the controlling agency which will help to keep you safe.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Squawk 7700, fly as high as possible, turn on all your lights, broadcast your intentions on 121.5 if you aren't talking to ATC, and don't make any sudden dives toward the ground/buildings, etc.  This will all help to show that you aren't trying to &quot;sneak in under the radar&quot; and can only improve your situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't be surprised if you get intercepted though, and make sure that you talk to them on 121.5 if you do.  Know your &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;intercept procedures (section 5-6-2)&lt;/a&gt; and follow them exactly.  They will most likely try to help you as much as possible.  You will still face a lot of questions and probably even certificate action when you get on the ground though because, as you said, poor planning is no excuse....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, this applies in the US. Some other countries (possibly Cuba, Iran, etc.) tend to be far more sensitive to issues like this and may &quot;shoot first and ask questions later&quot;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-07-01T22:20:44.090" LastActivityDate="2015-07-01T22:20:44.090" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1038" PostTypeId="2" ParentId="1035" CreationDate="2014-01-14T14:55:19.943" Score="14" Body="&lt;p&gt;Aviate, Navigate, Communicate.  In that order.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, solve the in-flight emergency.  If that truly means penetrating prohibited or restricted airspace, do it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, navigate to exit the prohibited or restricted airspace as soon as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, Communicate to ATC what you are doing and why.  Follow instructions given if they don't conflict with your safety. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, when on the ground, file a NASA ASRS report.  Explain what/where/why.  Pictures etc to document this are a good idea but not in flight.  You have an emergency situation... what are you fiddling with a camera for?  Take them on the ground.  If you have time to take in-flight photos (icing) they can be used against you unless you have a plane certified for flight in icing conditions.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-14T14:55:19.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1039" PostTypeId="2" ParentId="1007" CreationDate="2014-01-14T15:04:27.840" Score="3" Body="&lt;p&gt;If the pilot flubs the flare and landing, the result is frequently survivable.  The reason is that even a flubbed autorotation will reduce the vertical speed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Student and instructor walked away from this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nydailynews.com/news/national/helicopter-crashes-westchester-county-airport-article-1.1560222&quot; rel=&quot;nofollow&quot;&gt;http://www.nydailynews.com/news/national/helicopter-crashes-westchester-county-airport-article-1.1560222&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-14T15:39:00.113" LastActivityDate="2014-01-14T15:39:00.113" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1040" PostTypeId="1" AcceptedAnswerId="1041" CreationDate="2014-01-14T15:21:40.330" Score="6" ViewCount="1476" Body="&lt;p&gt;Not factoring learning curve, personal safety minimums, and pilot proficiency, what is the absolute minimum flight time that must be logged in order to carry a passenger in a piston engine aircraft in the United States?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm am looking for an answer for the airplane category. Not gliders or ultralights.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="423" LastEditDate="2014-01-14T22:16:37.163" LastActivityDate="2014-01-14T22:16:37.163" Title="What is the minimum possible number of hours required to carry passengers?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;usa&gt;&lt;far-61&gt;&lt;logging&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1041" PostTypeId="2" ParentId="1040" CreationDate="2014-01-14T15:30:10.973" Score="10" Body="&lt;p&gt;I believe the answer, at least in the US is &lt;strong&gt;20 hours of flight time, plus however long a checkride takes.&lt;/strong&gt; A sport pilot can carry a single passenger and the minimum requirements are outlined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=625d5c266c877fc98a4aa57f38e91bd9&amp;amp;node=14:2.0.1.1.2&amp;amp;rgn=div5#14:2.0.1.1.2.10.1.7&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §61.313&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;If you are applying for a sport pilot certificate with&lt;/strong&gt; [...]&#xA;Airplane category and single-engine land or sea class privileges,&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Then you must log at least&lt;/strong&gt; [...]&#xA;20 hours of flight time, including at least 15 hours of flight training from an authorized instructor in a single-engine airplane and at least 5 hours of solo flight training in the areas of operation listed in §61.311,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If a sport pilot applicant logged exactly 20 hours, got signed off, and then passed their checkride on the first attempt... they would be able to fly passengers as soon as they completed the checkride. That means, realistically, probably 21 to 21.5 hours.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-14T15:52:10.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1042" PostTypeId="2" ParentId="1040" CreationDate="2014-01-14T15:56:38.557" Score="4" Body="&lt;p&gt;Zero, if you bring along a flight instructor :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You fly the plane, the flight instructor keeps you safe and legal, and your passenger sits in the back seat.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-01-14T15:56:38.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1043" PostTypeId="1" AcceptedAnswerId="1052" CreationDate="2014-01-14T16:00:16.853" Score="30" ViewCount="16711" Body="&lt;p&gt;Piston engines reach full rpm within a second or two, but turbines take much longer. Why is that?&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="1696" LastEditDate="2014-03-26T22:41:27.997" LastActivityDate="2017-04-21T19:03:02.687" Title="Why do turbine engines take so long to spool up?" Tags="&lt;jet-engine&gt;&lt;jet&gt;&lt;turbine&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1044" PostTypeId="2" ParentId="1043" CreationDate="2014-01-14T16:34:22.213" Score="1" Body="&lt;p&gt;Momentum is given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\mathrm{Momentum}=\mathrm{Mass}\times\mathrm{Velocity}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Work done is given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\mathrm{Work~done}=\mathrm{Force}\times\mathrm{Distance}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Work done is measured in watts, defined as joules per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing this, you can see how a battery will behave with a bigger load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet engine has a larger mass, and must reach a higher velocity. The work done to do so will increase too, with a more powerful battery doing more rotations. The thing is, it's not a &lt;em&gt;proportionally larger&lt;/em&gt; battery. If you gave jet planes a really powerful battery, the work done would be huge, and a lot of force would be applied in very little time (high wattage), so that it would start up in the same time as a prop. However, this would be very energy inefficient (due to heating), so it works out best to use a smaller battery to start up over a longer period of time.&lt;/p&gt;&#xA;" OwnerUserId="369" LastEditorUserId="946" LastEditDate="2014-12-05T08:53:28.160" LastActivityDate="2014-12-05T08:53:28.160" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1048" PostTypeId="1" AcceptedAnswerId="1055" CreationDate="2014-01-14T19:41:03.213" Score="4" ViewCount="1421" Body="&lt;p&gt;What 2 parts of the airframe are the first to have structural failure after exceeding maximum speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry. I just thought there might be a part that usually failed first.&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="580" LastEditDate="2014-01-14T22:55:19.557" LastActivityDate="2014-01-14T22:55:19.557" Title="Where are the first structural damages after maximum speed is passed?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;&lt;aircraft-limitations&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2014-01-14T22:38:52.297" ContentLicense="CC BY-SA 3.0" />
  <row Id="1049" PostTypeId="1" AcceptedAnswerId="1050" CreationDate="2014-01-14T19:41:38.127" Score="16" ViewCount="6040" Body="&lt;p&gt;In flight training we're warned against &lt;em&gt;skidding turns&lt;/em&gt; since they have a higher potential for a stall/spin (the classic example being the stall/spin on the base to final turn).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, how does the airplane behave during a stall entered from a &lt;em&gt;slip&lt;/em&gt;? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a cross-controlled condition, but since the rudder input is opposite to what it would be in a skid, is it more difficult, or not possible, to spin from such a situation?&lt;/p&gt;&#xA;" OwnerUserId="16" LastActivityDate="2016-12-22T17:07:29.600" Title="What happens in a stall during a slip?" Tags="&lt;aerodynamics&gt;&lt;spins&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1050" PostTypeId="2" ParentId="1049" CreationDate="2014-01-14T20:09:08.287" Score="13" Body="&lt;p&gt;In order for a spin to develop, you need two things from the airplane:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;it must be stalled&lt;/li&gt;&#xA;&lt;li&gt;it must be yawing.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since the airplane is not yawing while in a slip (it is actually flying straight ahead, although uncoordinated), the airplane simply won't spin.  Instead, when the stall occurs the higher wing (which has the higher angle of attack) will stall first, the wing will drop, and the wings will tend level.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, it is still a stall and can be dangerous at low altitudes.  It can also turn into a spin if you leave the rudder applied as the wings level and you come out of the slip (and into a skid).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best protection for all of this is to watch your airspeed and angle of attack to make sure that you always have sufficient airspeed so that you never stall in the first place.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Additional Information&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Since this has generated some debate, here is additional information:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Spin&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Spin_%28flight%29&quot;&gt;Wikipedia&lt;/a&gt; (emphasis added by me):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Spins can be entered intentionally or unintentionally, from any flight&#xA;  attitude and from practically any airspeed—&lt;em&gt;all that is required is&#xA;  sufficient &lt;strong&gt;yaw&lt;/strong&gt; rate while an aircraft is &lt;strong&gt;stalled&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Yaw&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;So this brings us to &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_principal_axes#Normal_axis_.28yaw.29&quot;&gt;Yaw - Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The yaw axis is defined to be perpendicular to the body of the wings&#xA;  with its origin at the center of gravity and directed towards the&#xA;  bottom of the aircraft. &lt;em&gt;A yaw motion is a movement of the nose of the&#xA;  aircraft from side to side&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Skid&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Skid_%28aerodynamic%29&quot;&gt;Skid - Wikipedia&lt;/a&gt; actually covers this exact scenario:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The skid is more dangerous than the slip if the airplane is close to a&#xA;  stall. In the slip, the raised wing — the left one if the airplane is&#xA;  turning to the right — will stall before the lowered one, and the&#xA;  airplane will reduce the bank angle, which prevents the stall. In the&#xA;  skid, the lowered wing will stall before the raised one, and the&#xA;  airplane will tighten the turn, and the stall can develop to a spin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Slip&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Slip_%28aerodynamic%29&quot;&gt;Slip - Wikipedia&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A slip is an aerodynamic state where an aircraft is moving somewhat&#xA;  sideways as well as forward relative to the oncoming airflow or&#xA;  relative wind. In other words, for a conventional aircraft, the nose&#xA;  will be pointing in the opposite direction to the bank of the wing(s).&#xA;  The aircraft is not in coordinated flight and therefore is flying&#xA;  inefficiently.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the &lt;em&gt;aircraft&lt;/em&gt; is moving sideways.  The nose of the aircraft is not moving, and it is therefore not yawing.  It also says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Often, if an airplane in a slip is made to stall, it displays very&#xA;  little of the yawing tendency that causes a skidding stall to develop&#xA;  into a spin. A stalling airplane in a slip may do little more than&#xA;  tend to roll into a wings level attitude. In fact, in some airplanes&#xA;  stall characteristics may even be improved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-14T22:36:53.960" LastActivityDate="2014-01-14T22:36:53.960" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="1051" PostTypeId="2" ParentId="738" CreationDate="2014-01-14T20:45:41.280" Score="38" Body="&lt;p&gt;I believe that there's an element to this question which has not been covered.  This is very much a personal response.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question specifically asks whether it can help you to learn how to fly or become a better pilot.  This is actually two questions in one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Physical and mental limitations not withstanding, I would say that just about anyone can learn how to fly.  But I don't believe that everyone who can learn how to fly could be a good pilot.  Flying and pilotage are very much more than successfully operating a flying machine in order to fly.  It's even a lot more than doing that and following the procedures (ATC, operating in controlled airspace etc) which accompany it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being a good pilot requires a certain aptitude and attitude (and I'm not talking about what you see on the AH).  It needs, let's not beat about the bush, a reasonably good IQ and education.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot becomes good when the operation of the machine or the following of the procedures is not enough to to produce a safe, successful conclusion.  A good pilot avoids the traps and pitfalls that catch the unwary and have proved the rule, all to often, that in the ongoing contest between the earth and flimsy machines arriving in other than controlled circumstances, the earth has yet to lose.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good pilot takes care of the machine and it's passengers.  A good pilot can deal with the unexpected and make sound decisions to continue a flight or not or perhaps even to not commit aviation at all.  A good pilot has situational awareness which tells them, via sixth sense, that the bizjet calling left base is a potential threat and is already looking by the time the tower calls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But much more than this, there are some very important elements to flying which a sim can never provide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is the emotional response; that thrill, that feeling of privilege, that unquantifiable human response to flying that is so much more than operating the machine.  There is also a set of skills and mental and physical responses without which, it is not possible to be a &quot;good pilot&quot; (IMHO).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me give a brief background of where I'm coming from and a concrete example of what I mean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have only a couple of hundred hours.  A handful on fixed wing, the rest on helicopters.  I also have about 3500 hours &quot;flying&quot; big tin on VATSIM (if you are serious about PC simming and don't know about VATSIM, Google for it right now!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In VATSIM, I can operate a 777 (my favourite) very successfully including all of the related procedures which VATSIM does a remarkably good job of simulating.  I can fly a SID, follow my planned route, follow a STAR and do a visual onto 26R at Heathrow without breaking sweat, talking to and complying with ATC all the way. I can deal with an unexpected hold or a last minute change of arrival without fluster. I know this all works because I have also been lucky enough to do this in a &quot;real&quot; sim (737) and I had no problems at all using the automatics and hand flying the machine for the first 500 and last 1000 feet to depart and arrive safely back at Heathrow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, when I was learning to fly a helicopter, the reality of it all was very different.  Hovering is like learning to ride a bike.  I would say anyone with reasonable co-ordination can learn to do it.  I can hover all helicopters I've flown with ease.  Without even thinking about it.  Thing is, I can't really tell you how to do it and I have never been able to keep a PC sim helicopter in the air for more than a few minutes without getting into horrible shape.  Try explaining to a child how to ride a bike.  I reckon it's impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you switch from lurching around the sky with your instructor calling &quot;I have control&quot; every 20 seconds to that magical moment when you are suddenly in a steady hover, there are some things which simply cannot be simulated which your brain needs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The beginners mistake is to focus on the ground, I think most people are looking about 15 metres ahead.  You cannot succeed like that.  What you want to do is focus your eyes well into the distance and let your peripheral vision do the work.  It's almost subconscious and I can't even tell you how it all works but you do realise that you are moving over the ground with subtle cues coming in from your periphery.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second, and more important set of cues, are those that come through the &quot;seat of your pants&quot;.  With a little experience, you just &quot;know&quot; when the helicopter moves, even before your peripheral vision has picked up the movement and you've already put that pressure on the cyclic (and it generally is pressure, not movement) to arrest the movement before the machine has deviated from it's position.  There are always small movements but to an external observer, you are sitting there, in the air, without so much as a ripple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Subtle sounds are also important.  I can tell you pretty much where the rotor RPM is without looking at the tach and can certainly tell instantly when it's going down.  The second cue is from the tach but by that time, I'm already on the collective to adjust.  The tach just qualifies what I know and shows me that I'm doing the right thing to correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure that the fixed wing guys could provide good parallels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My experience on sims tells me that you can indeed learn how to operate the machine and prosecute the procedures around it but it cannot help you to fly, nor to be a good (or better) pilot.  Where a sim can help is in teaching you the operation and procedures to the point where your brain is free to concentrate on flying and pilotage and your heart free to enjoy the sensations, because the mechanical stuff has moved into your subconscious and has become muscle memory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying is emotional; it's passionate; it's determination; it's personal conquest; it runs in your veins. It's many things more than a sim can ever provide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't get &quot;Oh I have slipped the surly bonds&quot;, then you are an operator, not a flyer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&#xA;Am I a good pilot?  I'd say I'm average, and striving to be better, but that, in reality, probably describes most pilots, since it is impossible for most to be better than average.  I do recognise that I'm in that statistically dangerous zone where I have enough hours to think I'm good but not enough hours to prove it.  In my experience, ego and cahonas tell many pilots that they &lt;strong&gt;are&lt;/strong&gt; good pilots ;)&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2014-11-11T08:31:27.977" LastActivityDate="2014-11-11T08:31:27.977" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1052" PostTypeId="2" ParentId="1043" CreationDate="2014-01-14T20:50:21.897" Score="41" Body="&lt;p&gt;I'm not an engineer (which might be better suited to answer this) so this is from simplified things they feed pilots:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines take much longer to spool up (i.e. increase RPM) than piston engines, especially at low RPM because of the pressure ratio/increased airflow necessary to keep the compressor from stalling/surging/blowing up every time when changing power settings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The (simplified) jet engine cycle contains a compressor that pushes air into a combustion chamber, where it burns, and then blows out the rear end rotating a turbine that moves the compressor from back where we started at. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you &quot;add more power&quot; (i.e. put more fuel in) it takes a while for that extra fuel to produce more thrust, which in turn takes a while to accelerate the turbine, which will make the compressor spin faster, which will finally bring more compressed air into the combustion chamber to utilize all that extra fuel you poured in at step 1. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding power all of a sudden will increase the pressure in the combustion chamber, so much that air that is &quot;upstream&quot; (i.e still in the compressor) does not want to advance. The extra pressure in the combustion chamber did not have enough time to spool up the turbine, so now the compressor is underpowered to keep &quot;pushing&quot; compressed air into the combustion chamber. Air starts flowing backwards (i.e. from combustion chamber to compressor), engine surges, all hell breaks loose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there is a lag (electronically these days, the pilots can floor the trust levers as fast as they like) when the engines are at low RPM, the FADEC only adds a little bit of extra fuel, waits for the airflow to stabilize, then adds a little more, and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the graph below might explain this. Every time you change RPM, you will increase Pressure Ratio (i.e. move up the graph), then you wait a little bit for Air Mass Flow to increase (i.e. move right). If you increase the Pressure Ratio too much, without the accompanying mass flow (which take a while because of inertia) you will enter the surge line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tpOCY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar thing happens on spool down, albeit a gentler one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this with the piston engine where you put more air/gas mixture into the cylinder, it makes for a bigger bang, accelerates the piston faster, and the very next piston cycle you can theoretically get max power.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="938" LastEditDate="2014-12-04T21:18:19.243" LastActivityDate="2014-12-04T21:18:19.243" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1054" PostTypeId="2" ParentId="1040" CreationDate="2014-01-14T21:53:34.870" Score="2" Body="&lt;p&gt;Top of my head:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;11.5 hours can get you an Ultralight license. Max 1 passenger and 750kg total weight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;46.5 hours will get you a PPL. You can carry up to 19 passengers, beyond that you need a type-rating on the airplane, so you add a few more hours (depends on airplane)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;202 hours will get you a CPL. Same as above, but now you are allowed to charge them for the flight.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-14T21:53:34.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1055" PostTypeId="2" ParentId="1048" CreationDate="2014-01-14T21:59:50.883" Score="3" Body="&lt;p&gt;Q: Which link of a chain will fail first when you exceed the maximum design tension?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A: The weakest link.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It could be any link since none is designed as the weakest link.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-14T21:59:50.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1056" PostTypeId="5" CreationDate="2014-01-14T22:10:31.370" Score="0" Body="&lt;p&gt;&quot;Preflight&quot; encompasses many aspects of preparing for a flight, including obtaining a flight briefing and computing weight-and-balance, however this tag deals mainly with the &lt;em&gt;preflight inspection&lt;/em&gt; - a basic check of the aircraft and its systems undertaken before each flight to ensure that no serious airworthiness issues or maintenance items (&quot;squawks&quot;) exist, and that the aircraft is in a condition to complete the flight safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Preflight steps vary for each aircraft, however they often begin with a manufacturer's preflight checklist, and include things like ensuring that the engine has sufficient fuel and oil, the landing gear tires are properly inflated, the flight controls are free and correctly rigged, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/skills/howtopreflight.html&quot; rel=&quot;nofollow&quot;&gt;AOPA has an excellent article on the basics of a preflight inspection&lt;/a&gt; for additional information.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="69" LastEditDate="2014-01-14T22:42:17.297" LastActivityDate="2014-01-14T22:42:17.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1057" PostTypeId="4" CreationDate="2014-01-14T22:10:31.370" Score="0" Body="Use this tag for questions about pre-flight inspections and aircraft preparation." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-14T23:07:04.437" LastActivityDate="2014-01-14T23:07:04.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1058" PostTypeId="2" ParentId="1048" CreationDate="2014-01-14T22:30:45.947" Score="1" Body="&lt;p&gt;Unfortunately it's impossible to answer your question. No part of any aircraft design will simply fail because the 'speed' is to high. You need to consider the airspeed (in this particular case the equivalent airspeed) as a force acting on the airframe and as Force stated correctly it's not the only factor, which needs to be considered. Mass, existing weakening of the structure and the attitude as well as the surface design, which obviously varies between different aircraft, need to be taken into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now tell a Pilot that he is not allowed to bank more than x1 degrees,  if the aircrafts mass is bigger than x2 or even lighter than x3, if the aircrafts last overhaul was more than x4 month ago, at a higer airspeed then x5 KEAS. He will refuse it - by the way the aircraft won't be certified because of its manual - as well as he would refuse to calculate the load factor while flying. Thats why maximum speeds are calculated or even set up during flight testing. VNE, VA, VFE, VLO... all expressed in KIAS. By the way 2 different aircraft flying the same KEAS will most probably don't have the same indicated airspeed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general you can say that at maybe 70 percent of all aircraft either the parts which carry the heaviest loads or those parts which are not reinforced to withstand high loads, because they don't have to during normal operation plus safety margins, fail first when exceeding VNE and the safety margin in straight and level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The never exceed speed can also be set as the aircraft becomes only very hard to control above it, there were no further tests and calculations made or for sure also some other reasons.&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-14T22:30:45.947" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1059" PostTypeId="5" CreationDate="2014-01-15T00:12:55.933" Score="0" Body="&lt;p&gt;ADS-B (Automatic Dependent Surveillance - Broadcast) is a cooperative surveillance technology for tracking aircraft. &#xA;It is:   &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Automatic&lt;/strong&gt; in the sense that it operates without external stimulus (unlike radar)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Dependent&lt;/strong&gt; in the sense that the surveillance information is derived from on board systems&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Surveillance&lt;/strong&gt; in the sense that it's primary intended to provide surveillance information to other parties&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Broadcast&lt;/strong&gt; because it transmits to all listeners without knowing who does listeners are, there is no two-way communication.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The capability of an aircraft to transmit ADS-B signals is called ADS-B OUT, the capability of an aircraft to receive ADS-B signals is called ADS-B IN.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B data contains information about the identity, position, altitude and velocity of the aircraft. The position and velocity information is derived from GNNS (GPS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three technologies defined for ADS-B&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;1090ES&lt;/strong&gt; is operating on 1090 MHz, the same frequency used for Secondary Surveillance Radar (SSR) and Airborne Collision Avoidance Systems (ACAS/TCAS). Messages are transmitted by the same transponder that also replies to radar interrogations. This will be a Mode-S capable transponder because the data is formatted in a similar way. Since this frequency is the worldwide used standard for aviation, international aviation will use this ADS-B standard.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Universal Access Transceiver (UAT)&lt;/strong&gt; works on 978 MHz. A special transceiver is required to use this form of ADS-B. The transceiver is able to send and receive data, it will also receive ADS-B transmissions from other aircraft. UAT is only allowed within the USA, the frequency 978 MHz is reserved for other purposes in other countries. Within Europe it is for example used for mobile telephony (GSM). To encourage people to equip with ADS-B voluntarily, the FAA provides additional services on UAT. These are Traffic Information Service - Broadcast (TIS-B) which transmits position of aircraft detected by FAA's SSR's and Flight Information Service - Broadcast (FIS-B) which provides the receiver with weather information and operational data such as airspace restrictions and NOTAMS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;VHF Datalink Mode 4 (VLDm4)&lt;/strong&gt; uses a frequency in the 118-136.975 MHz block, which is internationally reserved for aviation. Normally these frequencies are used for voice communications, so a special radio is required to support VDLm4. Just like UAT, VDL mode 4 allows for services like TIS-B and FIS-B. VDLm4 was tried in Sweden and Russia, but has not been able to gather much mass. It is unlikely that it will be used on a large scale.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information on ADS-B &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_dependent_surveillance-broadcast&quot; rel=&quot;nofollow noreferrer&quot;&gt;see the Wikipedia page&lt;/a&gt;.   &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="8282" LastEditDate="2018-10-07T18:45:18.227" LastActivityDate="2018-10-07T18:45:18.227" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1060" PostTypeId="4" CreationDate="2014-01-15T00:12:55.933" Score="0" Body="ADS-B (Automatic Dependent Surveillance - Broadcast) is a surveillance technology that works by broadcasting GNSS position, velocity and identity to interested parties. It can be used as a supplement to or alternative to radar systems for tracking aircraft. It is a component of the FAA's NextGen ATC improvements, as well as the European SESAR programme." OwnerUserId="64" LastEditorUserId="19" LastEditDate="2014-01-15T15:06:21.173" LastActivityDate="2014-01-15T15:06:21.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1061" PostTypeId="5" CreationDate="2014-01-15T03:07:20.030" Score="0" Body="&lt;p&gt;is for obtaining licenses, certificates, and ratings. It includes the required paperwork and testing, but not the training (use &lt;a href=&quot;/questions/tagged/flight-training&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-training&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-training&lt;/a&gt; instead).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2020-01-17T20:59:32.810" LastActivityDate="2020-01-17T20:59:32.810" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1062" PostTypeId="4" CreationDate="2014-01-15T03:07:20.030" Score="0" Body="is for obtaining licenses, certificates, and ratings. It includes the required paperwork and testing, but not the training (use [flight-training] instead)." OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2020-01-17T20:59:32.810" LastActivityDate="2020-01-17T20:59:32.810" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1063" PostTypeId="1" AcceptedAnswerId="1064" CreationDate="2014-01-15T03:36:32.153" Score="19" ViewCount="2715" Body="&lt;p&gt;So after the long wait, when someone finally gets that phone call for an interview at an airline, what do they need to study?  What kinds of questions will they ask during the interview?  How many interviews do they typically have to go through before a hire decision is made?  In short, how does it work?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-08T23:35:40.893" LastActivityDate="2014-11-20T14:05:45.167" Title="What can be expected in an airline interview?" Tags="&lt;airline-operations&gt;&lt;career&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1064" PostTypeId="2" ParentId="1063" CreationDate="2014-01-15T04:42:59.517" Score="26" Body="&lt;h1&gt;The Delta Interview Process&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I interviewed about three months ago at one of the several regionals that uses the Delta interview process.  It goes a little something like this:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Company Introduction&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You arrive in the morning, somebody meets you, shakes your hand, and you usually hear a little speech or presentation about the company.  If your prospective employer uses &lt;a href=&quot;http://www.airlineapps.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirlineApps&lt;/a&gt;, they'll have you verify that all of your information is still current, and gather your paperwork.  Then, it's off to Computer-Based Testing!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Computer Based Testing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;CBT in the Delta interview is divided into three segments: cognitive, personality, and job knowledge.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Cognitive&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The cognitive test is essentially reflex and memory games, of the sort you'd see on lumosity.com.  Some examples:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown a horizontal line, with a pointer in the center.  The pointer will move from side to side at random along the line.  It is your task to counteract this random movement using the arrow keys to keep the pointer as close as possible to the center of the line.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Focus and concentration&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown two words, such as &lt;code&gt;DF3ET&lt;/code&gt; and &lt;code&gt;DEFET&lt;/code&gt;.  It is your task to determine as quickly as possible if they are the same or different, and to click the appropriate &lt;kbd&gt;same&lt;/kbd&gt; or &lt;kbd&gt;different&lt;/kbd&gt; button on screen.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures: Attention to detail?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown a table of six numerals paired with six simple shapes.  This table remains on screen.  You are shown a series of these shapes.  Decode, as quickly as possible, the series of shapes into the numerals they represent.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Matching, working memory.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown a graphic of a man holding a flag in one hand.  The man is either facing towards or away from you.  The man is either right-side-up or upside-down.  No matter his orientation, determine as quickly as possible whether the man is holding the flag in his right or left hand.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Spatial awareness&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A line wavers back and forth in a white area between two red zones in a random fashion.  When the space bar is pressed, the line will instantly be reset to the center of the white area.  It is your task to press the space bar as quickly as possible after the red line leaves the white area, but not before.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Attention, reflexes.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown the horizontal line with the pointer as well as the white area with the line.  It is your task to keep the pointer centered with the arrow keys while simultaneously using the space bar to reset the line when and only when it moves outside the white area.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Division of attention, reflexes&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown a series of six simple shapes.  It is your task to recall the six numerals that were paired with these shapes from earlier in the test.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Recall&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A series of simple mental math problems is presented.  &quot;Which would you rather have, 1/4th of \$200, 1/5th of \$300, or 1/3 of \$250?&quot;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Mental math skills&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You are shown four rectangles.  One has a thin border, one contains a filled in arrow pointing left, one has a shaded arrow pointing right, one has a thick border.  There are multiple exercises to the test.  During some portions of the test, you are asked to click the rectangle whose arrow matches the direction of the one you are shown.  In others, you are asked to click the one whose shading matches.  In others, the border.  These criteria change at random.  Your task is to match the proper criteria as quickly and accurately as possible.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Attention to detail, adaptation to changing conditions.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Listen through your headphones.  A series of notes will be played.  Then a second series of notes will be played.  Touch &lt;kbd&gt;SAME&lt;/kbd&gt; or &lt;kbd&gt;DIFFERENT&lt;/kbd&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measures:  Whether you were good at &lt;a href=&quot;http://en.wikipedia.org/wiki/Simon_%28game%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Simon&lt;/a&gt; as a kid.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Personality&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;You are shown approximately 130 statements, one at a time.  Your task is to determine how much you agree or disagree with them on the following scale:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Strongly Agree&lt;/li&gt;&#xA;&lt;li&gt;Agree&lt;/li&gt;&#xA;&lt;li&gt;Neither agree nor disagree&lt;/li&gt;&#xA;&lt;li&gt;Disagree&lt;/li&gt;&#xA;&lt;li&gt;Strongly disagree&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The statements are similar to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I think the new morality is no morality at all.&lt;/li&gt;&#xA;&lt;li&gt;Over the years, I have done some pretty stupid things.&lt;/li&gt;&#xA;&lt;li&gt;I have literally jumped for joy.&lt;/li&gt;&#xA;&lt;li&gt;I have a hard time resisting temptation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Job Knowledge&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This test measures technical knowledge.  It contains questions concerning:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Turbine engine theory&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Descent planning &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;DME arc degree-to-nautical-mile calculations&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stall recovery procedures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Mach-to-TAS conversion&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Transport category systems knowledge&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Emergency procedures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aerodynamics&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;and more!&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Thank Wright that's out of the way, next up is lunch!&lt;/h2&gt;&#xA;&#xA;&lt;h2&gt;Then comes the interviews:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Tell me about a scary time in the cockpit&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/63/167&quot;&gt;What would you do if you were an FO and the captain arrived smelling like alcohol&lt;/a&gt;?&lt;/li&gt;&#xA;&lt;li&gt;Which is colder, -40 C or -40 F?&lt;/li&gt;&#xA;&lt;li&gt;I see that you failed a checkride, tell me about it.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And so on.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;The conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You made it!  Someone comes out and shakes your hand.  Now it's time to fill out PRIA paperwork and pee in a cup.  If all goes well, you're given a conditional offer of employment!  Congrats!  You're a regional FO!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If you can make it through training)&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-20T14:05:45.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1065" PostTypeId="1" AcceptedAnswerId="1075" CreationDate="2014-01-15T06:25:01.620" Score="5" ViewCount="1071" Body="&lt;p&gt;What are the main structural design software packages that are used by the most of the aircraft manufacturers. There are a number of software packages but which one is widely accepted and used for the structural design of the aeroplane.&lt;/p&gt;&#xA;" OwnerUserId="177" LastEditorUserId="69" LastEditDate="2014-01-15T15:27:03.487" LastActivityDate="2014-01-15T16:45:59.607" Title="Structural design software for airplanes" Tags="&lt;aircraft-design&gt;&lt;software&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ClosedDate="2014-01-15T21:41:54.793" ContentLicense="CC BY-SA 3.0" />
  <row Id="1066" PostTypeId="1" AcceptedAnswerId="1067" CreationDate="2014-01-15T07:29:52.370" Score="8" ViewCount="570" Body="&lt;p&gt;Say I have requested a special VFR to enter Class D airspace. Approach acknowledges and clears me into the Class D airspace. &lt;strong&gt;After&lt;/strong&gt; entering the Class D airspace the airport visibility drops &amp;lt; 1 mile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I required to exit the airspace or can I continue as normal?&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="69" LastEditDate="2014-01-17T20:48:46.553" LastActivityDate="2014-01-17T20:48:46.553" Title="Can Approach cancel my special VFR clearance if I'm already cleared?" Tags="&lt;faa-regulations&gt;&lt;visual-flight-rules&gt;&lt;special-vfr&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1067" PostTypeId="2" ParentId="1066" CreationDate="2014-01-15T08:50:49.120" Score="14" Body="&lt;p&gt;The clearance comes with the catch that you need to maintain the minimum visibility requirements and sky conditions, if you're not able to, you have no clearance, it's pretty much as simple as that. Either you need to navigate in such a way that you avoid the weather (which might require you to leave the airspace) or you can do one of two things&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Request an IFR clearance if you're rated and equipped&lt;/li&gt;&#xA;&lt;li&gt;Declare an emergency and land in the nearest suitable spot, assuming you can still see the ground&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If it is deteriorating so quickly that you cannot go back to where you came from (i.e. the weather is not better outside the D), you'd be flying illegally outside the D as well, so no point in going there really, but more importantly, if the weather is deteriorating that dramatically, you don't have much time before you'll be completely blind, and by that time you'll want to be on the ground with as little injuries as possible, no matter where or the condition of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the minimums are different depending on where you are (jurisdiction) and type of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-01-15T08:50:49.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1068" PostTypeId="2" ParentId="1049" CreationDate="2014-01-15T13:11:03.790" Score="0" Body="&lt;p&gt;You are indeed yawing in a coordinated turn, yes or no?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you stall in a coordinated turn, will you enter a spin?  I'll answer that one: No.  My CFI and I spent a few hours exploring accelerated stalls, both straight and turning.  This is not a spin entry maneuver.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the original statement you made that two things are necessary for a spin: stalled and yawing, is not completely correct.  It is stalled and uncoordinated.  I don't think this is just a nit we are picking.  Having said that, spins out of slips are rare.  In an aggressive slip, the nose can blank the airflow over one wing and if the pilot doesn't react immediately and appropriately, you are in a spin.  I discount the logic that a badly executed slip turns into a skid turns into a stall.  While possibly true aerodynamically, the purpose of our training is to prevent unintentional spins, and you can indeed get into a spin from a slip.  Your statement that you can't spin from a slip is just not helpful to the majority of pilots who are basically just in search of the Hundred Dollar Hamburger.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-15T13:11:03.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1069" PostTypeId="2" ParentId="1065" CreationDate="2014-01-15T15:10:28.203" Score="3" Body="&lt;p&gt;There are many package available for structural analysis, but I know that &lt;a href=&quot;http://en.wikipedia.org/wiki/Nastran&quot; rel=&quot;nofollow&quot; title=&quot;Nastran&quot;&gt;NASTRAN&lt;/a&gt;/&lt;a href=&quot;http://www.mscsoftware.com/product/patran&quot; rel=&quot;nofollow&quot; title=&quot;PATRAN&quot;&gt;PATRAN&lt;/a&gt; are used extensively in aerospace engineering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The software was originally developed for NASA in the sixties and has been expanded with a suite of problem solvers for various structural problems including fatigue and acoustics.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-15T15:10:28.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1070" PostTypeId="1" CreationDate="2014-01-15T15:25:10.970" Score="5" ViewCount="28897" Body="&lt;p&gt;How do I calculate the distance to touchdown when the glideslope angle is different from 3°? For example, you are 670ft AGL on a 3.2° glideslope approach; what do I change in the formula to calculate the distance?&lt;/p&gt;&#xA;" OwnerUserId="631" LastEditorUserId="62" LastEditDate="2014-01-15T16:28:24.653" LastActivityDate="2015-02-19T18:00:48.197" Title="How can I calculate distance based on altitude and glideslope angle?" Tags="&lt;navigation&gt;&lt;general-aviation&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1071" PostTypeId="2" ParentId="1070" CreationDate="2014-01-15T16:28:51.563" Score="2" Body="&lt;p&gt;Since the 1 in 60 rule of thumb yields a solution of 300 feet for every NM from the touchdown point for a 3 degree slope, use 320 feet for a 3.2 degree slope.  So 670ft, gives you a nadgers whisker over 2 nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be a little more precise, 2.09375 nm ($\frac{670}{320}$)&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2014-06-13T10:25:52.050" LastActivityDate="2014-06-13T10:25:52.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1072" PostTypeId="1" AcceptedAnswerId="1077" CreationDate="2014-01-15T16:33:03.203" Score="35" ViewCount="18180" Body="&lt;p&gt;Let's say I have business on a US military base (e.g. JBLM), and I'd like to fly a privately owned aircraft there. What is the process I follow before the flight to get approval to land, and once I'm enroute to ensure everything goes smoothly?&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="69" LastEditDate="2014-01-18T18:02:39.020" LastActivityDate="2020-04-30T20:17:37.877" Title="What process do I follow to land a civilian aircraft on a military base?" Tags="&lt;faa-regulations&gt;&lt;military&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1073" PostTypeId="2" ParentId="1070" CreationDate="2014-01-15T16:40:42.057" Score="2" Body="&lt;p&gt;The $300ft/NM$ used to calculate your height above the runway at a particular distance is just an approximation that is easy to remember, and is close enough for our purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a more exact number, you can use some trigonometry:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\tan(3)=\frac{xft}{6,076ft/NM}=318ft/NM$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(the &quot;real&quot; number).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For 3.2 degrees, it would be:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\tan(3.2)=\frac{xft}{6,076 ft/NM}=340ft/NM$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you want to know the appropriate altitude for, say a 3 mile final on a 3.2 degree glideslope, it would be:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Runway~Touchdown~Elevation+340ft/NM\times3NM=TDE+1,020ft$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your specific example where you already know the altitude and want to know when to start the descent, the answer would be $2NM$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{670ft}{340ft/NM}=2.0NM$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;($1.97$ if you want to be REALLY exact.)&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-18T03:32:18.893" LastActivityDate="2014-04-18T03:32:18.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1074" PostTypeId="2" ParentId="1070" CreationDate="2014-01-15T16:42:43.033" Score="1" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BCPb5.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;$$tan(3.2)=\frac{670}{a}$$&#xA;$$\frac{670}{\tan(3.2)}=a$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a=11,983ft$$&#xA;$$11,983ft=1.97NM$$&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="97" LastEditDate="2014-04-17T01:19:10.353" LastActivityDate="2014-04-17T01:19:10.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1075" PostTypeId="2" ParentId="1065" CreationDate="2014-01-15T16:45:59.607" Score="3" Body="&lt;p&gt;CATIA has been used in large projects like &lt;a href=&quot;http://www.boeing.com/boeing/commercial/777family/compute/compute2.page&quot; rel=&quot;nofollow&quot;&gt;Boeing 777&lt;/a&gt; and companies like &lt;a href=&quot;http://www.3ds.com/press-releases/single/lockheed-martin-expands-use-of-dassault-systemes-solutions-upgrades-delmia-robotics-implementation/&quot; rel=&quot;nofollow&quot;&gt;Lockheed Martin&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wouldn't say it is the standard across the aerospace industry though as other software like Pro E and Solidworks can be used as well. &lt;/p&gt;&#xA;" OwnerUserId="633" LastActivityDate="2014-01-15T16:45:59.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1076" PostTypeId="2" ParentId="1072" CreationDate="2014-01-15T17:04:33.240" Score="4" Body="&lt;p&gt;I'd never heard of JBLM but I guess you're referring to Joint Base Lewis-McChord which has the identifier KTCM? Airnav &lt;a href=&quot;http://www.airnav.com/airport/KTCM&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt; it's joint civilian and military use, AOPA &lt;a href=&quot;http://www.aopa.org/airports/KTCM&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt; it's private military, but the AF/D &lt;a href=&quot;http://aeronav.faa.gov/afd/12DEC2013/nw_170_12DEC2013.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt; it's joint, which should be the definitive answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, as a joint field then civilian flights should be OK but I would carefully read the entire AF/D entry as well as any other information it references and if you have any doubts or concerns at all then you should contact them in advance. Even if you don't, I would still contact them anyway and in this case the AF/D tells you to do exactly that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;tran acft parking extremely ltd. 24 hr prior coordination rqr&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Landing at a private military field on the other hand would require special permission from the military which I assume is very unlikely to be granted unless you have good connections on base.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update from an anonymous user:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The reason that AirNav says 'joint military/civillian use' is that at&#xA;  one time KGRF (the airfield on the Army side of JBLM, then a separate&#xA;  installation - Fort Lewis) had an 'Aero Club' that operated a flight&#xA;  school &amp;amp; rented Cessnas for use by the base population. They also&#xA;  allowed troops who owned personal aircraft to base them on field at&#xA;  the Aero Club. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;That Aero Club facility closed due to insufficient use during the&#xA;  height of Iraq/AFG deployments, and with it civil use of the JBLM&#xA;  runways ended. The ramp space is now used by military aviation units&#xA;  (an Army Combat Aviation Brigade) that moved to JBLM after the Aero&#xA;  Club closed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-07-25T21:30:03.200" LastActivityDate="2018-07-25T21:30:03.200" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="1077" PostTypeId="2" ParentId="1072" CreationDate="2014-01-15T17:47:56.580" Score="36" Body="&lt;p&gt;Landing at a US military base isn't all that hard (I've landed at Ft. Drum before), you just have to get prior permission (PPR) (submitted at least 30 days in advance and confirmed within 24 hours according to 32 CFR 855.8), and need to have a &quot;good reason&quot; (as determined by them).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=80a5b18b20a48d67997e6d51e202012c&amp;amp;node=32:6.1.1.6.10&amp;amp;rgn=div5#ap32.6.855_123.1&quot; rel=&quot;noreferrer&quot;&gt;32 CFR 855, Table 1&lt;/a&gt; (which is quite long) includes the purposes that are normally allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will be required to submit the following forms to the base commander (See the A/FD):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dtic.mil/whs/directives/infomgt/forms/eforms/dd2400.pdf&quot; rel=&quot;noreferrer&quot;&gt;DD Form 2400 - Civil Aircraft Certificate of Insurance&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dtic.mil/whs/directives/infomgt/forms/eforms/dd2401.pdf&quot; rel=&quot;noreferrer&quot;&gt;DD Form 2401 - Civil Aircraft Landing Permit&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dtic.mil/whs/directives/infomgt/forms/eforms/dd2402.pdf&quot; rel=&quot;noreferrer&quot;&gt;DD Form 2402 - Civil Aircraft Hold Harmless Agreement&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=80a5b18b20a48d67997e6d51e202012c&amp;amp;node=32:6.1.1.6.10&amp;amp;rgn=div5&quot; rel=&quot;noreferrer&quot;&gt;32 CFR 855&lt;/a&gt; contains the regulations pertaining to US Air Force airfields (and the rules are similar for each branch).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;855.1 - Policy&lt;/strong&gt; includes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Normally, landing permits will be issued only for civil aircraft&#xA;  operating in support of official Government business. Other types of&#xA;  use may be authorized if justified by exceptional circumstances.&#xA;  Access will be granted on an equitable basis.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Any aircraft operator with an inflight emergency may land at any&#xA;  Air Force airfield without prior authorization. An inflight emergency&#xA;  is defined as a situation that makes continued flight hazardous.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;855.5 - Responsibilities and authorities.&lt;/strong&gt; includes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(6) Will not authorize use of Air Force airfields:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) In competition with civil airports by providing services or&#xA;  facilities that are already available in the private sector.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note: Use to conduct business with or for the US Government is not&#xA;  considered as competition with civil airports.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Solely for the convenience of passengers or aircraft operator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Solely for transient aircraft servicing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) By civil aircraft that do not meet US Department of&#xA;  Transportation operating and airworthiness standards.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(v) That selectively promotes, benefits, or favors a specific&#xA;  commercial venture unless equitable consideration is available to all&#xA;  potential users in like circumstances.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vi) For unsolicited proposals in procuring Government business or&#xA;  contracts.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vii) Solely for customs-handling purposes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(viii) When the air traffic control tower and base operations are&#xA;  closed or when a runway is restricted from use by all aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="9461" LastEditDate="2016-10-06T15:24:56.577" LastActivityDate="2016-10-06T15:24:56.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1078" PostTypeId="2" ParentId="1070" CreationDate="2014-01-15T17:56:16.680" Score="2" Body="&lt;p&gt;Just in case you don't have a calculator at hand (yeah, I know...):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wolframalpha.com/input/?i=%28670ft%29/Tan%5B3.2%C2%B0%5D%20in%20nautical%20miles&quot; rel=&quot;nofollow noreferrer&quot;&gt;WolframAlpha&lt;/a&gt; returns (unsurprisingly): 1.97nm (and lot of other entertaining info).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wvmfi.png&quot; alt=&quot;Mathematica graphics&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sidenote: Because &lt;a href=&quot;https://en.wikipedia.org/wiki/Small-angle_approximation&quot; rel=&quot;nofollow noreferrer&quot;&gt;$\tan(\alpha)\approx\alpha~for~small~\alpha$&lt;/a&gt;, you can use a simple linear approximation in this case. Your new glide distance will be more or less $\frac{3}{3.2}=\frac{15}{16}=0.9375$ times the original one.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="97" LastEditDate="2014-04-17T01:10:30.667" LastActivityDate="2014-04-17T01:10:30.667" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1079" PostTypeId="1" CreationDate="2014-01-15T18:04:36.663" Score="12" ViewCount="547" Body="&lt;p&gt;I am currently a private pilot with an instrument rating and multi-engine rating.  I own and regularly fly my own twin engine airplane and have been thinking about getting my commercial rating.  Part of the PTS requirements for the commercial multi-engine include the emergency procedures for engine out/emergency descents, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Since I have already had a check ride (multi-engine rating) that included ALL of these maneuvers, do I still have to perform these on a commercial multi-engine check ride?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="635" LastEditorUserId="39" LastEditDate="2014-01-15T20:01:31.873" LastActivityDate="2014-01-15T20:01:31.873" Title="Do I have to do all exercises during a checkride, even if I did them in a previous one?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1080" PostTypeId="2" ParentId="1079" CreationDate="2014-01-15T18:36:52.737" Score="9" Body="&lt;p&gt;&lt;strong&gt;Yes, if this is your initial rating on a Commercial certificate, you have to do all of that rating's required tasks.&lt;/strong&gt; A checkride for a given certificate is always self-contained. In the case of an additional Commercial rating (ASEL, for example) you can refer to the appropriate &quot;Additional Rating Task Table&quot; and you'll see that some areas are already covered by the existing Commercial rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look closely, you'll notice that the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot;&gt;PTS standards&lt;/a&gt; for the same maneuvers are more precise for Commercial than they are for Private. Notice that Steep Turns differ in both bank angle and execution technique:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Commercial (from FAA-S-8081-12C)&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;Task A: Steep Turns (AMEL and AMES)&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;References: FAA-H-8083-3; POH/AFM.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Objective: To determine that the applicant:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Exhibits satisfactory knowledge of the elements related to steep turns.&lt;/li&gt;&#xA;  &lt;li&gt;Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Rolls into a coordinated 360° steep turn with at least a 50° bank, followed by a 360° steep turn in the opposite direction.&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Divides attention between airplane control and orientation.&lt;/li&gt;&#xA;  &lt;li&gt;Maintains the entry altitude, ±100 feet, airspeed, ±10 knots,&#xA;  bank, ±5°; and rolls out on the entry heading, ±10°.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Private (from FAA-S-8081-14B)&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;Task A: Steep Turns (AMEL and AMES)&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;References: FAA-H-8083-3; POH/AFM.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Objective: To determine that the applicant:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Exhibits satisfactory knowledge of the elements related to steep turns.&lt;/li&gt;&#xA;  &lt;li&gt;Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Rolls into a coordinated 360° turn; maintains a 45° bank.&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Performs the task in the opposite direction, as specified by&#xA;  the examiner.&lt;/li&gt;&#xA;  &lt;li&gt;Divides attention between airplane control and orientation.&lt;/li&gt;&#xA;  &lt;li&gt;Maintains the entry altitude, ±100 feet, airspeed, ±10 knots,&#xA;  bank, ±5°; and rolls out on the entry heading, ±10°.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-15T18:42:42.340" LastActivityDate="2014-01-15T18:42:42.340" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1081" PostTypeId="1" AcceptedAnswerId="1108" CreationDate="2014-01-15T19:54:31.703" Score="7" ViewCount="18619" Body="&lt;p&gt;Buried away in the front matter of the FAA charts is a section titled &quot;IFR TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES&quot;.  Note that this is &lt;strong&gt;&lt;em&gt;not&lt;/em&gt;&lt;/strong&gt; a graphical departure procedure that is in with the rest of the approach plates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aeronav.faa.gov/d-tpp/1401/SE1TO.PDF&quot;&gt;Knoxville, TN (KTYS)&lt;/a&gt; contains the following departure procedure in that section:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DEPARTURE PROCEDURE: Rwy 5L, climb heading 048°  to 3400 before&#xA;  proceeding on course. Rwy 5R, climb  heading 048° to 3500 before&#xA;  proceeding on course. Rwy  23L, climb heading 228° to 3500 before&#xA;  proceeding on  course. Rwy 23R, climb heading 228° to 3500 before &#xA;  proceeding on course.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Question: If I receive an IFR clearance along the lines of &quot;*N1234, cleared to XXX as filed, climb and maintain....&quot; and I didn't file any kind of departure, am I expected to fly the above ODP, and will ATC know what I'm doing if I do?  Does it matter if it is VMC or IMC? &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-17T03:01:41.327" Title="When should an Obstacle Departure Procedure (ODP) be used?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1082" PostTypeId="1" AcceptedAnswerId="1083" CreationDate="2014-01-15T19:55:35.737" Score="14" ViewCount="2788" Body="&lt;p&gt;There is a lot of confusion around what it means to have ADS-B.  What is the minimum equipment required to meet the mandate? Can I use a Stratus to meet that requirement?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="64" LastEditDate="2014-01-17T19:00:02.847" LastActivityDate="2017-04-10T21:06:59.280" Title="Will a portable ADS-B unit, like Stratus, meet the requirements for my aircraft to be ADS-B equipped by the 2020 mandate?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;ads-b&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1083" PostTypeId="2" ParentId="1082" CreationDate="2014-01-15T20:11:44.543" Score="13" Body="&lt;p&gt;The short version is &lt;strong&gt;&lt;em&gt;no&lt;/em&gt;&lt;/strong&gt; the Stratus will not meet the requirements, and for several reasons.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final rule requires ADS-B OUT (and the Stratus is only ADS-B IN) that meets particular TSO requirements (see below), and portable units will not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has an &lt;a href=&quot;http://www.faa.gov/nextgen/implementation/programs/adsb/faq/#7&quot;&gt;ADS-B FAQ&lt;/a&gt; on their website which has a lot of great ADS-B information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The minimum equipment required to meet the mandate is addressed by:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What equipment is required by the new rule?&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The rule specifies ADS-B&#xA;  Out equipment compliant with either Technical Standard Order&#xA;  (TSO)-C154c (Universal Access Transceiver) or TSO-C166b (1090 ES).&#xA;  However, to operate in Class A airspace, aircraft are required to&#xA;  equip with avionics certified to TSO-C166b.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAQ also specifically addresses the question of portable units and says that they will not be allowed:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Will the FAA allow portable/handheld units, or will they have to be panel mounts only?&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Installed transponders and GPS units must meet certification&#xA;  standards. Handheld devices and displays that serve only for&#xA;  situational awareness have more flexibility and are not certified&#xA;  installations. In order to comply with 14 CFR § 91.225 and 91.227&#xA;  aircraft intended to fly in ADS-B airspace must have installed and&#xA;  certified equipment. Portable installations are not compliant to the&#xA;  rule and would only be usable for receiving FIS-B services for&#xA;  situational awareness. The FAA is in the early stages of investigating&#xA;  a portable device for glider aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-15T20:37:24.697" LastActivityDate="2014-01-15T20:37:24.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1084" PostTypeId="2" ParentId="1081" CreationDate="2014-01-15T20:27:43.443" Score="-1" Body="&lt;p&gt;I'd recommend reading this link:&#xA;&lt;a href=&quot;http://expertaviator.com/2012/11/10/obstacle-departure-procedures-and-assign-headings/&quot; rel=&quot;nofollow&quot; title=&quot;expertaviator.com&quot;&gt;Obstacle Departure Procedures&lt;/a&gt;.&#xA;Seems to have the answer you're looking for: in short if you are IFR you must fly the ODP unless you meet one of the alternative requirements or ATC advises you otherwise. &lt;/p&gt;&#xA;" OwnerUserId="311" LastActivityDate="2014-01-15T20:27:43.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1085" PostTypeId="2" ParentId="1000" CreationDate="2014-01-15T22:03:56.440" Score="4" Body="&lt;p&gt;One of the distinctive feature often found on aerobatics aircraft ailerons are &lt;a href=&quot;http://en.wikipedia.org/wiki/Aileron#Spades&quot; rel=&quot;nofollow noreferrer&quot;&gt;spades&lt;/a&gt;. They are an efficient form of aerodynamic counterbalance that serve to reduce the effort needed on the stick to actuate the aileron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also serve to bring the centre of mass of the aileron forward of the hinge line in order to help prevent control surface flutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tazHY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Being more efficient than &quot;normal&quot; ailerons (i.e. achieving higher roll rate), aeroboatics ailerons would require much more torque to actuate (without counterbalance).&lt;/li&gt;&#xA;&lt;li&gt;The stick should be as &quot;light&quot; as possible to increase flight precision and reduce pilot fatigue .&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Cons&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Having a lighter control force can make it more difficult to find the centrepoint of the control quickly.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="94" LastEditorUserId="-1" LastEditDate="2014-02-24T18:35:13.810" LastActivityDate="2014-02-24T18:35:13.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1086" PostTypeId="1" AcceptedAnswerId="1088" CreationDate="2014-01-16T02:01:09.203" Score="27" ViewCount="13472" Body="&lt;p&gt;My experience in aviation is essentially zero, but looking at Wikipedia it seems like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-95&quot; rel=&quot;noreferrer&quot;&gt;Tu-95 Bear&lt;/a&gt; offers high subsonic speed and extreme range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that turboprop engines are more fuel efficient than jet engines. If all the above are true then why we do not get to see more rotary engine planes in commercial airline flights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a noise concern? I see that the TU-95 is apparently the &quot;noisiest military aircraft on Earth&quot;.&lt;/p&gt;&#xA;" OwnerUserId="564" LastEditorUserId="12720" LastEditDate="2017-03-24T22:55:28.970" LastActivityDate="2019-09-12T14:48:43.443" Title="Why are propeller engines uncommon on airliners?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;&lt;piston-engine&gt;&lt;turboprop&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1087" PostTypeId="1" CreationDate="2014-01-16T02:52:35.017" Score="21" ViewCount="80141" Body="&lt;p&gt;This approach shows two sets of minimums that both have vertical guidance with a Decision Altitude (DA).  What is the difference between LNAV/VNAV and LPV, and why does LPV have lower minimums?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aeronav.faa.gov/d-tpp/1401/05942R26.PDF&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/46n0T.png&quot; alt=&quot;KFXE RNAV 26 Approach plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2018-11-16T16:05:48.467" LastActivityDate="2019-03-23T07:00:26.227" Title="What is the difference between LNAV/VNAV and LPV minimums on an RNAV approach?" Tags="&lt;iaps&gt;&lt;rnav&gt;" AnswerCount="7" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1088" PostTypeId="2" ParentId="1086" CreationDate="2014-01-16T02:52:42.280" Score="34" Body="&lt;p&gt;Well, first let's clear up a few terms: &#xA;When you say &quot;rotary&quot; engine I'm assuming you're referring to &lt;a href=&quot;http://en.wikipedia.org/wiki/Radial_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;radial engines&lt;/a&gt;, a type of piston engine that used to be pretty common on aircraft. (These days &lt;a href=&quot;http://en.wikipedia.org/wiki/Opposed-piston_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;opposed piston engines&lt;/a&gt; are what you typically find on piston-powered aircraft, &lt;a href=&quot;http://en.wikipedia.org/wiki/Rotary_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;rotary engines&lt;/a&gt; are yet another design, but their usage died out around the end of World War I.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The TU-95 is not actually a piston-powered aircraft.  It's a &lt;a href=&quot;http://en.wikipedia.org/wiki/Turboprop&quot; rel=&quot;nofollow noreferrer&quot;&gt;turboprop&lt;/a&gt; – basically a turbine engine similar to what you'd find in a jet, only rigged up to turn a propeller rather than produce &quot;jet thrust&quot; directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From an efficiency standpoint, turbine engines are usually more fuel efficient than their piston counterparts, and jet fuel is denser and less refined than aviation gasoline and is consequently cheaper for operators to procure. Turbine engines also offer more reliability than piston engines, and the maintenance on a turboprop engine is also largely similar to a jet engine with a few extra components, which is an advantage for a company operating a fleet of jet and propeller driven aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The differences in operating efficiency and reliability are the major reason why gasoline-powered piston engines have basically disappeared from scheduled airline service.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So why don't we see more turboprops? Actually we see a lot of them, if you look in the right places.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jets and Turboprops are good at different things: broadly simplifying, a turboprop is more efficient at lower altitudes and airspeeds while a jet engine is more efficient at higher altitudes and airspeeds.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result we see turboprop aircraft like &lt;a href=&quot;http://en.wikipedia.org/wiki/ATR_72&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATR 72s&lt;/a&gt; in use for short-haul &quot;commuter&quot; service, but for trans-continental or trans-oceanic flights where they spend a long time cruising at high altitude jets dominate the sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since most people are flying to go relatively long distances there are comparatively more jets in scheduled airline service than turboprops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noise is probably also a factor: fast turboprops like the Bear are &lt;strong&gt;&lt;em&gt;LOUD&lt;/em&gt;&lt;/strong&gt; not due to the engine, but due to the propeller.  The tips of the spinning propeller on a TU-95 can approach supersonic speeds, which causes quite a bit of noise. The TU-95's &lt;a href=&quot;http://en.wikipedia.org/wiki/Contra-rotating_propellers&quot; rel=&quot;nofollow noreferrer&quot;&gt;contra-rotating propellers&lt;/a&gt; (which help produce thrust more efficiently) also contribute to a louder noise footprint.  In the case of the TU-95 this doesn't matter – it's a military plane, and the Russian air force doesn't care if people complain as the aircraft has a mission to complete and that's more important than a few noise complaints.  If United Airlines were to operate a TU-95 out of Kennedy departing over people's houses I suspect they would quickly reconsider their choice of equipment when the noise complaints started coming in....&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="11671" LastEditDate="2019-09-12T14:48:43.443" LastActivityDate="2019-09-12T14:48:43.443" CommentCount="16" CommunityOwnedDate="2014-01-16T02:52:42.280" ContentLicense="CC BY-SA 4.0" />
  <row Id="1089" PostTypeId="2" ParentId="1086" CreationDate="2014-01-16T03:31:43.863" Score="0" Body="&lt;p&gt;Noise should not be the problem. Modern turbo prop driven aircraft are even more quiet compared to similar aircraft driven by jet engines. It is - like always - all about economy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's talk about the available engine types. (All you experienced aviators, I'll keep it very simple and so in some points even not 100% correct. If you don't like this, please skip this paragraph, if you like to have moe details on an engine type, please feel free to ask your questions) &lt;strong&gt;Piston engines&lt;/strong&gt; are the earliest engines and still most common or light sport aircraft. You can compare them to the engine in your car, but instead of driving the gearbox which drives your wheels, they drive a propeller (sometimes also via a gearbox). Piston engines strong enough to power an airliner, as they did in the past, consume far too much fuel and oil to be efficient enough to compete with jet engines.  There are different types of &lt;strong&gt;jet engines&lt;/strong&gt;. The classic jet engine &lt;em&gt;sucks&lt;/em&gt; in air with its fan, &lt;em&gt;squeeze&lt;/em&gt; it in a compressor, makes it go &lt;em&gt;bang&lt;/em&gt; in a combustion chamber and &lt;em&gt;blows&lt;/em&gt; it out, while a turbine ahead of the nozzle uses a bit of this energy to drive the fan and the compressor - remember this four words and you will always know how it works ;) This simple kind of jet engine was used for early jet driven passenger planes, but nowadays you'll only find it in military jets. Modern passenger aircraft use the same principle, but their engines have a far bigger fan &lt;strong&gt;turbo fan engines&lt;/strong&gt;. Most of the air is bypassed around the &quot;core&quot; of the engine. This air delivers more than half of the thrust.. There are also &lt;strong&gt;turbo prop engines&lt;/strong&gt;: simply replace the fan with a propeller. And finally &lt;strong&gt;turbo shaft&lt;/strong&gt; engines where all of the jet engines power is used to drive a propeller and the exhaust delivers no forward energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where does all this noise come from? To keep it simple, we can say that differences in speed produce noise. Jet engines are noisy because of the high difference in speed of the air passed through the engine and the free air stream. The cold air stream of a turbo fan engine is slower so there is less speed difference at the exhaust and less noise. The noise of propeller engines is mostly dependent on the speed of the propeller. The tips of the propeller blades are obviously the fastes moving parts. Their design requires them to remain subsonic to deliver thrust but propeller speed as well as the speed of the fan in turbo fan engines is more and more reduced to reduce noise emissions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An economic engine must not only be quite but also powerful as well as fuel efficient. You are right turbo prop engines are generally the most fuel efficient engines but would you as a passenger like to sit ten hours in an airplane to get from London to New York? I don't and most airliners won't like such a plane too, because flight time costs money. Turboprop aircraft are most efficient on short distances where the difference in speed doesn't makes such a huge difference in flight time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another problem with turbo prop engines are the passengers. There are many people who see an propeller and think that they are sitting in one of the oldest airplanes ever. They trust in jet engines,  low wing design and everything you would find on an &quot;modern&quot; passenger airplane drawn by a seven years old child.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope you'll find your answer, considering all this really basic and simplified knowledge.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="2176" LastEditDate="2014-12-08T13:41:44.850" LastActivityDate="2014-12-08T13:41:44.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1090" PostTypeId="2" ParentId="1087" CreationDate="2014-01-16T03:35:02.540" Score="7" Body="&lt;p&gt;LPV is a higher precision approach requiring equipment beyond what is needed for LNAV/VNAV. In particular you need dual WAAS recievers in a certified installation. The improved guidance is what allows the lower DH. &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Localizer_performance_with_vertical_guidance&quot;&gt;See this link for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-16T03:35:02.540" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1091" PostTypeId="2" ParentId="1087" CreationDate="2014-01-16T03:40:36.607" Score="2" Body="&lt;p&gt;LPV - Localizer Performance with Vertical Guidance is some kind of enhanced satellite navigation with an required accuracy of 16 meters in the horizontal and 20 meters in the vertical plane during 95 percent of the time, achieved by multiple special GPS (WAAS) receivers.  Obviously this accuracy allows to reduce the minima on the approaches.&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-01-16T03:40:36.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1092" PostTypeId="1" AcceptedAnswerId="1095" CreationDate="2014-01-16T13:13:13.783" Score="6" ViewCount="1644" Body="&lt;p&gt;I regularly fly a DA42 4-seater equipped with a G1000 system. Sometimes my passengers in the rear seats complain that the radio volume is too loud for them but it is OK for me (intercom is just right for everybody). Reason probably is that I am using a very different headset than them which I assume has a higher impedance and thus requires more electrical power for the same audio volume. If I turned down the COM volume it would be too quiet for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if there is any trick to adjusting/balancing the volume in such a setup. &lt;/p&gt;&#xA;" OwnerUserId="332" LastEditorUserId="19" LastEditDate="2016-07-28T15:04:36.100" LastActivityDate="2016-07-28T15:04:36.100" Title="G1000: Is it possible to balance the radio volume for pilots and passengers?" Tags="&lt;avionics&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1093" PostTypeId="2" ParentId="1087" CreationDate="2014-01-16T15:29:39.497" Score="10" Body="&lt;p&gt;LNAV/VNAV approaches were originally designed for larger, more sophisticated turbine aircraft utilizing onboard Flight Management Systems (FMS). These types of approaches uses barometric altimeters and ground radio equipment to compute a descent path and add vertical guidance to an existing non-precision approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An LPV approach still provides vertical guidance but is not a precision approach. In this type of approach WAAS GPS satellite and ground-based data are used to provide the aircraft with the vertical descent information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually a WAAS approved GPS navigator, like the Garmin 430w, is capable of flying both LPV and LNAV/VNAV approaches.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="1696" LastEditDate="2018-11-16T16:03:13.930" LastActivityDate="2018-11-16T16:03:13.930" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="1094" PostTypeId="2" ParentId="1092" CreationDate="2014-01-16T15:33:51.293" Score="3" Body="&lt;p&gt;Intercom Volume Control is the rotary knob on the bottom of the Audio Panel. The small knob controls the pilot ICS volume, while the large knob controls the copilot/passenger ICS volume. Just be sure to be in VOL mode (VOL in the lower left to be illuminated).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Volume for Coms/Navs are controlled by the COM radio volume control located on both the PFD and MFD, but (as far as I know) you cannot set that volume independently for pilot/copilot/passenger.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-16T15:33:51.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1095" PostTypeId="2" ParentId="1092" CreationDate="2014-01-16T16:02:56.600" Score="6" Body="&lt;p&gt;You can't control the radio volume separately for the passengers but you can control the intercom volume separately. If the passengers' headsets have individual volume controls you can ask them to turn down the volume and you can then compensate by turning up the passenger volume for the intercom. That way the overall intercom volume will be about the same but the radio/ATC volume will be lowered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all else fails, you could turn off the radio completely for your passengers :-)&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2014-01-16T16:02:56.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1096" PostTypeId="1" AcceptedAnswerId="1097" CreationDate="2014-01-16T18:54:33.830" Score="12" ViewCount="1526" Body="&lt;p&gt;So the LOC/DME-E approach to KASE lists for the missed approach course to use the I-PKN localizer, but then there's a note 'course outbound is normal sensing'.  Does that mean that in effect, this particular LOC is installed 'backwards' so when flying away from it you get normal indications?  How common is this?  Only for LOC-defined missed approaches?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/B6UnT.png&quot; alt=&quot;KASE LOC/DME-E pproach plate&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="72" LastEditDate="2014-03-03T05:28:51.493" LastActivityDate="2021-03-15T15:23:45.537" Title="Why do some back course operations use normal sensing?" Tags="&lt;iaps&gt;&lt;navigation&gt;&lt;instrument-flight-rules&gt;&lt;localizer&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1097" PostTypeId="2" ParentId="1096" CreationDate="2014-01-16T19:23:59.627" Score="8" Body="&lt;p&gt;Notice that in the plan view, the shading of the localizers are on the opposite sides. If you are flying south-west, the actual localizer used for the approach has the shading on the right, while the one used for the missed approach has the shading on the left. This can also be used to tell you what sensing to expect.  The note is also there to make it more obvious that the sensing will be backwards from what you might expect when flying outbound on a &quot;normal&quot;  localizer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, this particular localizer is designed to transmit backwards and you will get &lt;em&gt;indications that would be normal while flying inbound&lt;/em&gt; when flying outbound on the missed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that because of the high terrain/mountains in the area that they wanted to make it as easy as possible to fly without getting confused as to which way you are supposed to turn.  Combined with the fact that it is never used in a situation where you would be flying inbound makes it a perfect candidate to reverse the sensing.  Unfortunately, in my mind it actually makes it harder to understand.  We are taught from the beginning of our instrument training how to handle flying a localizer outbound, and now we have to do it the opposite way.  Rather confusing if you ask me, but you get used to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as &quot;how common is it&quot;, this is the only one that I've seen (but I'm &lt;strong&gt;guessing&lt;/strong&gt; that there are others)....&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-16T21:50:48.233" LastActivityDate="2014-01-16T21:50:48.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1098" PostTypeId="2" ParentId="170" CreationDate="2014-01-16T19:32:28.903" Score="11" Body="&lt;p&gt;This will not work in a large commercial airplane but if you are flying a smaller airplane (think Cessna), especially in a crowded airspace, I try to make it into the passenger briefing that if they spot any traffic coming our way, I probably know about it, but they should feel free to call it, including direction and relative height. It never hurts to have the extra pairs of eyes, and passengers seems to enjoy the extra responsibility bestowed upon them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, chances are the pilot is aware of any situation long before the passengers.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-16T19:32:28.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1099" PostTypeId="1" AcceptedAnswerId="1100" CreationDate="2014-01-16T19:55:26.517" Score="2" ViewCount="507" Body="&lt;p&gt;I'm starting to save up to get my pilots license and I was thinking I might be able to do some amount of prep work by using a flight simulator.  That being said, I realize there must be some huge limitations to what I can actually learn, on my own, on a flight sim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, out of curiosity, are there good things to try practicing on my own in a flight sim?  There's got to be a few basic things that would make it worth my time...  Otherwise I'll just go back to flying around aimlessly like I usually do :).&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-01-16T20:31:52.860" Title="Advantages in using a flight sim to prep for a private license?" Tags="&lt;flight-training&gt;&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-01-16T20:49:49.500" ContentLicense="CC BY-SA 3.0" />
  <row Id="1100" PostTypeId="2" ParentId="1099" CreationDate="2014-01-16T20:31:52.860" Score="7" Body="&lt;p&gt;I'd advise against &quot;flying around aimlessly&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if it is a simple, routine flight between two nearby airports, fly it fully, and try to fly it as professionally as possible (can you keep your heading to within +/- 3 degrees? can you keep your altitude spot-on?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another good exercise is to do all your navigation planning in detail (each heading for a certain number of minutes), then try to take off, and using nothing but the compass and stopwatch, find out how close you get.  (and when you end up off-course, figure out where you went wrong!)&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-16T20:31:52.860" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1101" PostTypeId="1" AcceptedAnswerId="1105" CreationDate="2014-01-16T22:03:29.660" Score="6" ViewCount="3694" Body="&lt;p&gt;Has the FAA regulated yet the maximum dBs of noise an aircraft's engine is allowed to generate, and what the range of &quot;safe operation&quot; would be? If they have, what are their regulations on it?&lt;/p&gt;&#xA;" OwnerUserId="327" LastEditorUserId="327" LastEditDate="2015-12-06T14:01:53.783" LastActivityDate="2015-12-06T14:01:53.783" Title="What is the maximum amount of noise an aircraft is allowed to generate?" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;&lt;icao&gt;&lt;noise&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1102" PostTypeId="1" CreationDate="2014-01-16T22:09:11.173" Score="13" ViewCount="5010" Body="&lt;p&gt;Is someone who holds a current EASA PPL(A) allowed to operate an FAA &quot;November&quot; registered aircraft in Europe? Of course I'm talking about a type of aircraft and of operation he or she would be allowed to conduct with an, for example, German-registered aircraft.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="97" LastEditDate="2014-04-22T06:40:56.307" LastActivityDate="2017-09-03T13:55:27.393" Title="Is someone holding an EASA PPL (A) allowed to operate a &quot;November&quot; registered aircraft in Europe?" Tags="&lt;faa-regulations&gt;&lt;ppl&gt;&lt;easa-regulations&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1103" PostTypeId="2" ParentId="1102" CreationDate="2014-01-16T22:43:33.907" Score="9" Body="&lt;p&gt;This is regulated by the FAA in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.3&quot;&gt;FAR 61.3&lt;/a&gt; &lt;strong&gt;and&lt;/strong&gt; local regulations specific to each country&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;(a) Required pilot certificate for operating a civil aircraft of the&#xA;  United States. No person may serve as a required pilot flight&#xA;  crewmember of a civil aircraft of the United States, unless that&#xA;  person:&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Has in the person's physical possession or readily accessible in&#xA;  the aircraft when exercising the privileges of that pilot certificate&#xA;  or authorization—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) A pilot certificate issued under this part and in accordance with&#xA;  § 61.19; (ii) A special purpose pilot authorization issued under §&#xA;  61.77;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) A temporary certificate issued under § 61.17;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) A document conveying temporary authority to exercise certificate&#xA;  privileges issued by the Airmen Certification Branch under § 61.29(e);&#xA;  or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(v) When operating an aircraft within a foreign country, a pilot&#xA;  license issued by that country may be used.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To operate a US-registered aircraft you either need an FAA license or a pilot license issued by the country where the aircraft is operated in. This also means that you are not allowed to fly into another country, unless you also have a license issued by that country. Even if individual countries allow foreign registered aircraft to be operated by a license holder of another (non-FAA) country, it would still be a violation of FAR 61.3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line: if you want to fly a N-registered aircraft without an FAA pilot license in Europe, you need a pilot license issued by every country you're flying into. For example, if you plan a trip from The Netherlands to Portugal you would need 5 different EASA PPL licenses issued by The Netherlands, Belgium, France, Spain and Portugal.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-04-21T21:18:16.553" LastActivityDate="2014-04-21T21:18:16.553" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1104" PostTypeId="2" ParentId="1101" CreationDate="2014-01-16T23:10:01.607" Score="5" Body="&lt;p&gt;If it can be regulated it shall be regulated -- the relevant section of law is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.19&amp;amp;idno=14&quot; rel=&quot;noreferrer&quot;&gt;FAR 36 - NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS CERTIFICATION&lt;/a&gt;, with a number of &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.list/parentTopicID/112&quot; rel=&quot;noreferrer&quot;&gt;advisory circulars as well&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These requirements are aimed mainly at Transport Category aircraft, and the absolute noise level limits are rather high (certainly nothing you'd want to be standing near without hearing protection).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's probably of more interest to most people are the &lt;a href=&quot;http://www.faa.gov/airports/environmental/airport_noise/&quot; rel=&quot;noreferrer&quot;&gt;FAA's guidelines on &lt;strong&gt;&lt;em&gt;Airport Noise&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt;, and specifically &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/order/energy_orders/1050-1E.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 1050-1E&lt;/a&gt;, which deals with the noise you are actually exposed to on the ground (rather than what is generated by the plane's engines).&lt;br&gt;&#xA;Order 1050-1E goes into great detail on what is considered &quot;acceptable&quot; noise levels for various types of land use around airports.  Airport construction and/or expansion projects are evaluated against these criteria using computational models to ensure that noise levels will not exceed the FAA's guidelines.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-16T23:10:01.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1105" PostTypeId="2" ParentId="1101" CreationDate="2014-01-16T23:13:30.837" Score="5" Body="&lt;p&gt;The answer can be found in Annex 16 of the ICAO, a copy including the noise limits can be found &lt;a href=&quot;http://www.dfld.de/Downloads/Annex_16.pdf&quot; rel=&quot;nofollow&quot;&gt;here (PDF)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below a little excerpt from the annex:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) For acoustical changes to Stage 1 airplanes, regardless of the&#xA;  number of engines, the noise levels prescribed under § 36.7(c) of this&#xA;  part.&#xA;  What are the 'Chapter 2' and 'Chapter 3' aircraft noise classifications?&#xA;  Certificated noise levels for larger aircraft are classified by the ICAO 'Standards and Recommended Practices – Aircraft Noise: Annex 16 to the Convention on International Civil Aviation' into a) Chapter 2 types, characterised by the noisier, low bypass turbofan aircraft and early high bypass turbofan aircraft, and b) Chapter 3 types, characterised by the modern, quieter, high bypass turbofan aircraft. Under European legislation, since 2002, 'Chapter 2' aircraft (of over 34 tonnes maximum take-off weight or with more than 19 seats) have no longer been allowed to operate at European airports. There are separate noise certification schemes for small propeller aircraft and for helicopters.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For any Stage 2 airplane regardless of the number of engines:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Flyover: 108 EPNdB for maximum weight of 600,000 pounds or more;&#xA;  for each halving of maximum weight (from 600,000 pounds), reduce the&#xA;  limit by 5 EPNdB; the limit is 93 EPNdB for a maximum weight of 75,000&#xA;  pounds or less.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Lateral and approach: 108 EPNdB for maximum weight of 600,000&#xA;  pounds or more; for each halving of maximum weight (from 600,000&#xA;  pounds), reduce the limit by 2 EPNdB; the limit is 102 EPNdB for a&#xA;  maximum weight of 75,000 pounds or less.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) For any Stage 3 airplane:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Flyover.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) For airplanes with more than 3 engines: 106 EPNdB for maximum&#xA;  weight of 850,000 pounds or more; for each halving of maximum weight&#xA;  (from 850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89&#xA;  EPNdB for a maximum weight of 44,673 pounds or less;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) For airplanes with 3 engines: 104 EPNdB for maximum weight of&#xA;  850,000 pounds or more; for each halving of maximum weight (from&#xA;  850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89 EPNdB&#xA;  for a maximum weight of 63,177 pounds or less; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) For airplanes with fewer than 3 engines: 101 EPNdB for maximum&#xA;  weight of 850,000 pounds or more; for each halving of maximum weight&#xA;  (from 850,000 pounds), reduce the limit by 4 EPNdB; the limit is 89&#xA;  EPNdB for a maximum weight of 106,250 pounds or less.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Lateral, regardless of the number of engines: 103 EPNdB for&#xA;  maximum weight of 882,000 pounds or more; for each halving of maximum&#xA;  weight (from 882,000 pounds), reduce the limit by 2.56 EPNdB; the&#xA;  limit is 94 EPNdB for a maximum weight of 77,200 pounds or less.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Approach, regardless of the number of engines: 105 EPNdB for&#xA;  maximum weight of 617,300 pounds or more; for each halving of maximum&#xA;  weight (from 617,300 pounds), reduce the limit by 2.33 EPNdB; the&#xA;  limit is 98 EPNdB for a maximum weight of 77,200 pounds or less.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) For any Stage 4 airplane, the flyover, lateral, and approach&#xA;  maximum noise levels are prescribed in Chapter 4, Paragraph 4.4,&#xA;  Maximum Noise Levels, and Chapter 3, Paragraph 3.4, Maximum Noise&#xA;  Levels, of the International Civil Aviation Organization (ICAO) Annex&#xA;  16, Environmental Protection, Volume I, Aircraft Noise, Third Edition,&#xA;  July 1993, Amendment 7, effective March 21, 2002. [Incorporated by&#xA;  reference, see § 36.6].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="213" LastEditorUserId="65" LastEditDate="2015-03-04T18:07:10.750" LastActivityDate="2015-03-04T18:07:10.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1106" PostTypeId="1" AcceptedAnswerId="1107" CreationDate="2014-01-16T23:27:03.307" Score="22" ViewCount="7149" Body="&lt;p&gt;I'm pretty sure that there are no aircraft equipped with a brake on its nose wheel, however two of my colleagues think there might have been.  Are there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft with retractable gear of course have devices to stop the wheels from spinning when retracted,  but I'm asking about brakes used to stop or slow down the aircraft. Please don't consider aircraft with a tail wheel, gliders, experimental aircraft, or aircraft used for flight testing (certified aircraft only).&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="69" LastEditDate="2014-01-17T00:25:51.520" LastActivityDate="2019-06-07T02:33:09.947" Title="Are there any aircraft with a nose wheel braking system?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1107" PostTypeId="2" ParentId="1106" CreationDate="2014-01-16T23:41:40.663" Score="24" Body="&lt;p&gt;There are quite a few 727 that actually had nose wheel braking, however they utilized it only for maximum braking power. (Also they were proven to be ineffective and unreliable, so a service bulletin was written to remove the system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Saab Gripens use nose wheel brakes to stop as well, the main gear sits farther aft than most planes, so there is quite a bit of weight on the nose gear, which makes it effective for stopping.&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="3825" LastEditDate="2015-11-23T23:13:07.343" LastActivityDate="2015-11-23T23:13:07.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1108" PostTypeId="2" ParentId="1081" CreationDate="2014-01-17T00:28:00.237" Score="4" Body="&lt;p&gt;According to the definition of the FAA it is a recommended procedure, so there is generally no need to follow it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;OBSTACLE DEPARTURE PROCEDURE (ODP)- A preplanned instrument flight rule (IFR) departure procedure printed for pilot use in textual or graphic form to provide obstruction clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or radar vector) has been specifically assigned by ATC. (Source: &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/O.HTM&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Pilot/Controller Glossary&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/29651A3A1F5D129186257384006CB41D?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.175&lt;/a&gt; you are responsible to ensure sufficient obstacle clearance if the airport is IFR (of course also if the airport is VFR).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(f) Civil airport takeoff minimums. This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter.&#xA;  (1) Unless otherwise authorized by the FAA, no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter.&#xA;  (2) If takeoff weather minimums are not prescribed under part 97 of this chapter for a particular airport, the following weather minimums apply to takeoffs under IFR:&#xA;  (i) For aircraft, other than helicopters, having two engines or less--1 statute mile visibility.&#xA;  (ii) For aircraft having more than two engines--1/2 statute mile visibility.&#xA;  (iii) For helicopters--1/2 statute mile visibility.&#xA;  (3) Except as provided in paragraph (f)(4) of this section, no pilot may takeoff under IFR from a civil airport having published obstacle departure procedures (ODPs) under part 97 of this chapter for the takeoff runway to be used, unless the pilot uses such ODPs.&#xA;  (4) Notwithstanding the requirements of paragraph (f)(3) of this section, no pilot may takeoff from an airport under IFR unless:&#xA;  (i) For part 121 and part 135 operators, the pilot uses a takeoff obstacle clearance or avoidance procedure that ensures compliance with the applicable airplane performance operating limitations requirements under part 121, subpart I or part 135, subpart I for takeoff at that airport; or&#xA;  (ii) For part 129 operators, the pilot uses a takeoff obstacle clearance or avoidance procedure that ensures compliance with the airplane performance operating limitations prescribed by the State of the operator for takeoff at that airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case it seems to be the easiest way to follow the ODP, but it's not binding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/69/lnafziger&quot;&gt;Lnafziger &lt;/a&gt; correctly commented that this is not applicable for part 91 operation. That's why I like to add a part of this &lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=6198&quot; rel=&quot;nofollow noreferrer&quot;&gt;Article&lt;/a&gt;, which I've found on the AOPA website, to my answer.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] We cannot assume that ATC will assign any special routing or altitude based on the ODP. They expect the pilot to fly the procedure if necessary without further clearance. FAA Order 7110.65R, Air Traffic Control--the controller's handbook--states, &quot;If a published IFR departure is not included in an ATC clearance, compliance with such a procedure is the pilot's prerogative.&quot; In other words, you have to decide whether you need to follow a specific route or procedure and fly accordingly. Now, we might think this is wrong, dangerous, and dumb, but it is the way procedures are arranged.[...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to all this information ATC would expect you to follow this procedure, at least in IMC. If you like to fly it in VMC and it does not disagree with your ATC clearance you are also welcome to do so. If there is any confusion I tend to ask and clarify the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases an ODP says that you should climb on runway heading at least until passing xxx feet before turning in a direction. I would always comply with it and if there is severe CAVOK and ATC then asks me to turn earlier, I would do it, so everyone is happy and on the safe side.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-01-17T03:01:41.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1109" PostTypeId="1" AcceptedAnswerId="1126" CreationDate="2014-01-17T00:35:52.547" Score="38" ViewCount="5878" Body="&lt;p&gt;I saw a sign at the Smithsonian about the Space Shuttle where it said that their gear was not extended until 50 feet above the ground.  I've searched and searched for something definitive that had the actual procedures used, but can't find anything.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put this in perspective, the policy for every jet that I have flown has been to have the gear down and locked between 1,500 ft. and 500 ft. (at the very lowest).  50 feet seems very very low! What happens if it doesn't come down on the first try and they need time to troubleshoot?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="13197" LastEditDate="2016-05-06T22:06:53.747" LastActivityDate="2016-05-06T23:25:07.353" Title="Did the Space Shuttle really wait until 50 feet above the ground before they put the gear down?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;nasa&gt;&lt;space-shuttle&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1110" PostTypeId="2" ParentId="1109" CreationDate="2014-01-17T02:24:58.453" Score="16" Body="&lt;p&gt;The official source says that the landing gear is deployed &lt;a href=&quot;http://spaceflight.nasa.gov/shuttle/reference/shutref/sts/profile.html&quot;&gt;at around 1700ft AGL&lt;/a&gt;, however I suspect an error in that statement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the document though, the spaceshuttle has a 1.5 degree glideslope in the short final and around 200kt. In &lt;a href=&quot;http://www.youtube.com/watch?v=YOxZsbyjSb8&quot;&gt;this video&lt;/a&gt; the landing gear is extended 18 seconds before the touchdown. 1.5° glideslope equals 2.6% glide path (tan 1.5). 200kt are 337.56 ft/s and 2.6% of that are 8.8 ft/s. The space shuttle is therefore descending with about 9ft/s in the very short final. 9*18 equals 162, which means that in this video the gear was extended at roughly 160ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, these are rough estimates. Before the short final the space shuttle has a descent rate of 10,000ft/min, therefore it might be, that it was even higher in the video. But even though if it was 10ft/s, that would mean that for 50ft the gear is not extended five seconds before touchdown, not counting the time it actually takes to extend it into a safe position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The link Qantas 94 Heavy posted in the comment says &quot;300 ± 100 feet&quot;, so it would be somewhat close to that. My guess is, that the spaceshuttle is still faster than 200 kt at this point and therefore has a higher sinkrate.&lt;/p&gt;&#xA;" OwnerUserId="213" LastEditorUserId="213" LastEditDate="2014-01-17T13:46:13.893" LastActivityDate="2014-01-17T13:46:13.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1111" PostTypeId="1" AcceptedAnswerId="1113" CreationDate="2014-01-17T05:57:58.437" Score="9" ViewCount="1481" Body="&lt;p&gt;If I'm flying in conditions that are conducive to carburetor icing, and my carb-heat cable becomes in-operable, is there anything I can do to prevent engine failure if my carburetor starts icing up? Assuming there are no immediate landing-areas to stop and fix the problem.&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="1696" LastEditDate="2018-04-16T18:15:29.410" LastActivityDate="2018-04-16T18:15:29.410" Title="What can I do if my carb-heat cable breaks in-flight?" Tags="&lt;piston-engine&gt;&lt;aircraft-operations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1112" PostTypeId="2" ParentId="1111" CreationDate="2014-01-17T06:43:13.863" Score="2" Body="&lt;p&gt;On some planes, the alternate air source is heated by the engine and may be better than no heat at all. Running the engine leaner can help, because carb ice is blocks the air, making the engine run too rich. A higher RPM can help, but moving the throttle may knock loose the ice and kill the engine.&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="110" LastEditDate="2014-01-17T06:56:57.667" LastActivityDate="2014-01-17T06:56:57.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1113" PostTypeId="2" ParentId="1111" CreationDate="2014-01-17T07:59:28.587" Score="12" Body="&lt;p&gt;Well, this depends a little on your situation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;strong&gt;&lt;em&gt;all&lt;/em&gt;&lt;/strong&gt; cases your goal is get on the ground in a controlled manner that leaves the pilot, passengers, and airframe intact - so obviously you'll be heading for the nearest airport (and if you can get in contact with ATC and explain your situation doing so would be a really good idea).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;No signs of carb ice (yet).&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;If you're flying in conditions conducive to carburetor icing but &lt;em&gt;don't yet have signs of icing&lt;/em&gt; there are a few things you can do to help prevent it from forming:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Seek a warmer/drier altitude&lt;/strong&gt;&lt;br&gt;&#xA;There's &lt;a href=&quot;https://i.stack.imgur.com/sgAx5.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;a wonderful diagram I'm sure everyone has seen&lt;/a&gt; that gives an idea of the probability of carb ice. If you can find an altitude where the temperature/dew point spread is less conducive to carb ice formation fly there until you can land.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Lean the mixture (as practical)&lt;/strong&gt; to limit evaporative cooling from the fuel vaporizing.&lt;br&gt;&#xA;This can limit the temperature drop in the carburetor, and if it's only a few degrees of difference between ice and no ice it might help.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Avoid low-power operation&lt;/strong&gt; (&amp;lt;60% power).&lt;br&gt;&#xA;A partially closed throttle plate is more likely to pick up ice (there is a greater pressure drop across the throttle plate which means a greater temperature drop).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;&quot;Clear&quot; the engine periodically&lt;/strong&gt; by opening &amp;amp; closing the throttle.&lt;br&gt;&#xA;This helps ensure the throttle plate does not freeze in place, and can dislodge any small ice patches before they become a more serious problem.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I think this would qualify as an &quot;urgency&quot; situation (&lt;code&gt;pan-pan&lt;/code&gt;), &lt;a href=&quot;https://aviation.stackexchange.com/questions/908/when-should-the-term-pan-pan-be-used-instead-of-mayday&quot;&gt;per this answer&lt;/a&gt;.&lt;br&gt;&#xA;  If you can get in contact with ATC don't hesitate to let them know that.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Signs of carb ice are apparent.&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;If you &lt;em&gt;do&lt;/em&gt; have signs of carb icing you can do all of the things above too, but how effective they are may vary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/1112/64&quot;&gt;xpda noted&lt;/a&gt; adjusting the mixture can help (typically carb ice makes the engine run over-rich).&lt;br&gt;&#xA;In extreme cases wide-open throttle and an aggressively leaned mixture may keep the engine producing power (and will reduce the pressure drop across the throttle plate, possibly bringing the carb temperature up enough that the ice will melt off).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In many light singles your alternate air &lt;em&gt;is&lt;/em&gt; the carb heat box, but if you have an alternate air source for the engine &lt;em&gt;besides&lt;/em&gt; carb heat that may be worth trying as well (especially if it's in the engine compartment or heated cabin). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Carburetor icing with carb heat inoperative is a bona-fide &lt;strong&gt;emergency&lt;/strong&gt;.&lt;br&gt;&#xA;  I can't imagine &lt;em&gt;not&lt;/em&gt; making a &lt;code&gt;mayday&lt;/code&gt; call in this case. Best-case scenario you wind up making an uneventful landing with fire trucks waiting to greet you ; Worst-case scenario you wind up landing somewhere that's not an airport, but at least someone &lt;em&gt;knows where you are&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-01-17T07:59:28.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1114" PostTypeId="2" ParentId="1017" CreationDate="2014-01-17T11:08:38.920" Score="13" Body="&lt;p&gt;&lt;strong&gt;FAA&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a compilation of what I could find relevant to the question. Feel free to come up with corrections if I missed anything (I'm an EASA FCL guy)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Co-pilot Landing Currency:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Part 61: 3 takeoff/landings in previous 12 months (61.55)    &lt;/li&gt;&#xA;&lt;li&gt;Part 135: no requirements other than those in part 61 (above)&lt;/li&gt;&#xA;&lt;li&gt;Part 121: 3 takeoff/landings in previous 90 days (121.439)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Co-pilot Instrument Currency:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Part 61: no requirements for SIC&lt;/li&gt;&#xA;&lt;li&gt;Part 135: 135.245 requires that SIC's must meet part 61 PIC instrument currency requirements in 61.57(c) (see below)&lt;/li&gt;&#xA;&lt;li&gt;Part 121: recurrent flight training every 12 months, including at least 1 ILS approach to minimums&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Following is the list of relevant FARs :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/2D89A60C90C6A9F786257BAA00701F54?OpenDocument&quot;&gt;§ 61.55 Second-in-command qualifications&lt;/a&gt;&lt;/strong&gt;   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Except as provided in paragraph (d) of this section, no person may serve as a second in&#xA;  command of an aircraft type certificated for more than one required&#xA;  pilot flight crewmember or in operations requiring a second in command&#xA;  unless that person has within the previous 12 calendar months:&lt;br&gt;&#xA;  (2)&#xA;  Except as provided in paragraph (e) of this section, performed and&#xA;  logged pilot time in the type of aircraft or in a flight simulator&#xA;  that represents the type of aircraft for which second-in-command&#xA;  privileges are requested, which includes --&lt;br&gt;&#xA;  (i) Three takeoffs and&#xA;  three landings to a full stop as the sole manipulator of the flight&#xA;  controls; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) This section does not apply to a person who is:[...operating part&#xA;  121,125,135...] &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) The holder of a commercial or airline transport&#xA;  pilot certificate with the appropriate category and class rating is&#xA;  not required to meet the requirements of paragraph (b)(2) of this&#xA;  section, provided the pilot: [... is not carrying paying&#xA;  passengers...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/DA8A38C5CABEDB6086257C24005B6A1E?OpenDocument&quot;&gt;§ 61.57 Recent flight experience: Pilot in command.&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) General experience.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Except as provided in paragraph (e) of this section, no person may&#xA;  act as a pilot in command of an aircraft carrying passengers or of an&#xA;  aircraft certificated for more than one pilot flight crewmember unless&#xA;  that person has made at least three takeoffs and three landings within&#xA;  the preceding 90 days, [...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Instrument experience.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Except as provided in paragraph (e) of this section, no person may act&#xA;  as pilot in command under IFR or in weather conditions less than the&#xA;  minimums prescribed for VFR, unless within the preceding 6 calendar&#xA;  months, that person has: [...6 approaches, holdings, intercepting&#xA;  &amp;amp;tracking course...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/742A3BE5161B716F8625694A006FCE64?OpenDocument&quot;&gt;§ 135.245 Second in command qualifications&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) [...] no certificate holder may use any person, nor may any person&#xA;  serve, as second in command of an aircraft unless that person holds at&#xA;  least a commercial pilot certificate with appropriate category and&#xA;  class ratings and an instrument rating. For flight under IFR, that&#xA;  person must meet the recent instrument experience requirements of part&#xA;  61 of this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is an excerpt from an &lt;a href=&quot;http://www.offhand.org/amb/pic-time.txt&quot;&gt;FAA Legal Interpretation&lt;/a&gt; concerning 135.245:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Next, unlike a PIC, an SIC's qualification to operate an aircraft&#xA;  under IFR in part 135 service is not dependent on compliance with §&#xA;  135.297.  Rather, § 135.245 sets the qualifications for pilots serving as SIC in part 135 operations.  It states that a pilot must meet the&#xA;  instrument experience requirements of part 61 to serve as SIC in&#xA;  flight under IFR.  Section 61.57(c) sets out the recent instrument&#xA;  flight experience requirements which include, among other things, six&#xA;  instrument approaches within the previous six months.  &lt;em&gt;See&lt;/em&gt; Legal&#xA;  Interpretation to Gerald Naekel, from Donald P. Byrne, Assistant Chief&#xA;  Counsel Regulations and Enforcement Division (June 18, 1991) (noting&#xA;  that although the section title refers to pilots in command, the&#xA;  instrument recency requirements of that section apply to SICs).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/801F8FE17B7A21FD86256DBF006D906F?OpenDocument&quot;&gt;§ 135.247 Pilot qualifications: Recent experience.&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No certificate holder may use any person, nor may any person&#xA;  serve, as pilot in command of an aircraft carrying passengers unless,&#xA;  within the preceding 90 days, that person has—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Made three takeoffs and three landings as the sole manipulator of&#xA;  the flight controls in an aircraft of the same category and class and,&#xA;  if a type rating is required, of the same type in which that person is&#xA;  to serve; or [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/EA93832A91C2F123852566EF006CED77?OpenDocument&quot;&gt;§ Part 121.433 Training required&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c)Recurrent training. (1) No certificate holder may use any person&#xA;  nor may any person serve as a required crewmember on an airplane&#xA;  unless, within the preceding 12 calendar months --  (i) For flight&#xA;  crewmembers, he has satisfactorily completed recurrent ground and&#xA;  flight training for that airplane and crewmember position and a flight&#xA;  check as applicable; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/0FB1260DF69B855B852566EF006CF4DC?OpenDocument&quot;&gt;§ Part 121.439 Pilot qualifications: Recent experience.&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No certificate holder may use any person nor may any person serve&#xA;  as a required pilot flight crewmember, unless within the preceding 90&#xA;  days, that person has made at least three takeoffs and landings in the&#xA;  type airplane in which that person is to serve.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EASA&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FCL is very clear about it: PIC and co-pilot both need to be landing current. If holding an IR rating then specific night currency is not required. No instrument currency is required as long as the IR is valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FCL.060 Recent experience&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Aeroplanes, helicopters, powered-lift, airships and sailplanes. A&#xA;  pilot shall not operate an aircraft in commercial air  transport or&#xA;  carrying passengers: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) &lt;strong&gt;as PIC or co-pilot&lt;/strong&gt; unless he/she has carried out, in the preceding&#xA;  &lt;strong&gt;90 days&lt;/strong&gt;, at least &lt;strong&gt;3 take-offs, approaches and  landings&lt;/strong&gt; in an aircraft&#xA;  of the same type or class or an FFS representing that type or class.&#xA;  The 3 take-offs and landings shall be performed in either multi-pilot&#xA;  or single-pilot operations, depending on the privileges held by the &#xA;  pilot; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) as PIC at night unless he/she: &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(i) has carried out in the preceding 90 days at least 1 take-off,&#xA;    approach and landing at night as a pilot flying in an aircraft of the&#xA;    same type or class or an FFS representing that type or class; or &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(ii) holds an IR;&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="419" LastEditorUserId="69" LastEditDate="2014-01-21T20:14:02.563" LastActivityDate="2014-01-21T20:14:02.563" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1116" PostTypeId="1" CreationDate="2014-01-17T16:21:40.553" Score="7" ViewCount="18267" Body="&lt;p&gt;With the intention of landing, taking off, or entering the traffic pattern at an airport in Class E airspace, what is the minimum ceiling and visibility as a VFR pilot in the USA.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="97" LastEditDate="2014-01-28T07:37:11.050" LastActivityDate="2019-12-15T22:45:48.050" Title="What is the minimum ceiling and visibility limits in Class E airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;visual-flight-rules&gt;&lt;far-91&gt;&lt;class-e-airspace&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1117" PostTypeId="1" CreationDate="2014-01-17T16:27:14.860" Score="13" ViewCount="4390" Body="&lt;p&gt;If you are on a heading, being vectored to intercept final on an instrument approach, and it appears that you will fly through the final approach without being cleared to intercept it, what should you do?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="72" LastEditDate="2014-03-03T05:31:13.177" LastActivityDate="2021-01-13T16:41:07.200" Title="What is the procedure when being vectored for an approach and ATC allows you to pass through the final approach course?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;approach&gt;&lt;instrument-flight-rules&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1118" PostTypeId="2" ParentId="1117" CreationDate="2014-01-17T16:32:21.320" Score="20" Body="&lt;p&gt;Usually when ATC has a need to vector you across the final approach course, they will tell you about it before they do.  Something along the lines of &quot;N1234 fly heading 230, vectors across final for spacing.&quot;.  If they don't and you see that you are getting close, you should ask them if they want you to intercept the course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AIM addresses this in paragraph &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot;&gt;5-4-3 Approach Control&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) After release to approach control, aircraft are vectored to the&#xA;  final approach course (ILS, MLS, VOR, ADF, etc.). Radar vectors and&#xA;  altitude or flight levels will be issued as required for spacing and&#xA;  separating aircraft. Therefore, pilots must not deviate from the&#xA;  headings issued by approach control. Aircraft will normally be&#xA;  informed when it is necessary to vector across the final approach&#xA;  course for spacing or other reasons. If approach course crossing is&#xA;  imminent and the pilot has not been informed that the aircraft will be&#xA;  vectored across the final approach course, the pilot should query the&#xA;  controller.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The pilot is not expected to turn inbound on the final approach&#xA;  course unless an approach clearance has been issued. This clearance&#xA;  will normally be issued with the final vector for interception of the&#xA;  final approach course, and the vector will be such as to enable the&#xA;  pilot to establish the aircraft on the final approach course prior to&#xA;  reaching the final approach fix.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA Air Traffic Control Order &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0509.html&quot;&gt;Section 9 - Radar Arrivals&lt;/a&gt; also has the following directive for approach controllers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-9-3. VECTORS ACROSS FINAL APPROACH COURSE&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Inform the aircraft whenever a vector will take it across the final&#xA;  approach course and state the reason for such action.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;em&gt;In the event you are unable to so inform the aircraft, the pilot is not expected to turn inbound on the final approach course unless&#xA;  approach clearance has been issued.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;&lt;strong&gt;PHRASEOLOGY-&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;em&gt;EXPECT VECTORS ACROSS FINAL FOR (purpose).&lt;/em&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;&lt;strong&gt;EXAMPLE-&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;em&gt;“EXPECT VECTORS ACROSS FINAL FOR SPACING.”&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-17T16:44:15.343" LastActivityDate="2014-01-17T16:44:15.343" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1119" PostTypeId="2" ParentId="1116" CreationDate="2014-01-17T16:49:20.553" Score="6" Body="&lt;p&gt;VFR cloud clearance requirements are listed in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/074608a2fa18b48a86256eeb006704ef!OpenDocument&quot;&gt;14 CFR 91.155&lt;/a&gt; and for Class E airspace specifies:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Class E:&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;em&gt;Less than 10,000 feet MSL.&lt;/em&gt;&lt;br&gt;&#xA;  Flight Visibility: 3 statute miles&lt;br&gt;&#xA;  Distance From Clouds: 500 feet below, 1,000 feet above, 2,000 feet&#xA;  horizontal.     &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;At or above 10,000 feet MSL.&lt;/em&gt;&lt;br&gt;&#xA;  Flight Visibility: 5 statute miles&lt;br&gt;&#xA;  Distance From Clouds: 1,000 feet below, 1,000 feet above, 1 statute&#xA;  mile horizontal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is also a requirement specific to Class E &lt;em&gt;surface areas&lt;/em&gt; that says that the ceiling must be &lt;em&gt;at least&lt;/em&gt; 1,000 feet in order to operate in the airspace.  It is also listed in 91.155:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Except as provided in Sec. 91.157, no person may operate an&#xA;  aircraft beneath the ceiling under VFR within the lateral boundaries&#xA;  of controlled airspace designated to the surface for an airport when&#xA;  the ceiling is less than 1,000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that there are exceptions for both of these that refer to &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/688420e12b4f38e9862576e300703639!OpenDocument&quot;&gt;91.157 Special VFR Weather Minimums&lt;/a&gt; if you are instrument rated and the aircraft is instrument equipped.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-17T16:55:52.427" LastActivityDate="2014-01-17T16:55:52.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1120" PostTypeId="1" AcceptedAnswerId="1125" CreationDate="2014-01-17T17:22:24.117" Score="5" ViewCount="3738" Body="&lt;p&gt;I realize that airlines can operate with different numbers of Pilots and Flight Attendants, depending on the route, aircraft and length of flight (EET). Which are the types of crew members that an airline can have, with the correct titles? I've heard about captains, master captains and cruise captains, but how can I identify them during the flights?  &lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="69" LastEditDate="2014-01-18T18:07:15.027" LastActivityDate="2015-02-12T00:06:49.983" Title="What are common airline crew titles and positions?" Tags="&lt;airline-operations&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1121" PostTypeId="1" AcceptedAnswerId="1122" CreationDate="2014-01-17T17:47:58.693" Score="19" ViewCount="3670" Body="&lt;p&gt;Some light aircraft now have airframe parachutes. If a pilot does have to pull the chute on a Cirrus (for example), is the aircraft flyable or at least repairable after landing or is it a write-off? What G forces are involved in the impact? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that there are lots of possible variables here, but let's assume that the parachute deploys correctly and in plenty of time for a stabilized descent; touchdown is in 'ideal' conditions, i.e. on level, unobstructed ground; and impact forces are as described in the &lt;a href=&quot;http://cirrusaircraft.com/static/img/CAPS_Guide.pdf&quot;&gt;Cirrus CAPS guide&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane will assume its touchdown attitude to optimize occupant&#xA;  protection. The airplane will descend under the canopy at less than&#xA;  1700 fpm and ground impact is expected to be equivalent to dropping&#xA;  from a height of 13 feet (about 4 meters). The airframe, seats and&#xA;  landing gear are all designed to absorb the impact energy.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="97" LastEditDate="2014-11-09T02:34:12.490" LastActivityDate="2016-03-01T21:43:08.743" Title="Is a light aircraft still usable after a successful airframe parachute deployment?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;airframe-parachute&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1122" PostTypeId="2" ParentId="1121" CreationDate="2014-01-17T18:56:25.293" Score="17" Body="&lt;p&gt;For the Cirrus at least, it sounds like that the odds are that the plane will be a loss.  Thus far of 53 CAP deployments, only &quot;9 CAPS Planes that Were Repaired and Flew Again&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Revision A7 of the Cirrus SR22 POH currently states &quot;CAPS deployment is expected to result in damage to the airframe&quot; that updates the earlier language that &quot;The system is intended to saves the lives of the occupants but will most likely destroy the aircraft.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.cirruspilots.org/copa/safety_programs/w/safety_pages/723.cirrus-caps-history.aspx&quot;&gt;https://www.cirruspilots.org/copa/safety_programs/w/safety_pages/723.cirrus-caps-history.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="526" LastActivityDate="2014-01-17T18:56:25.293" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1123" PostTypeId="5" CreationDate="2014-01-17T19:21:52.490" Score="0" Body="&lt;p&gt;Jet engines are engines which propel aircraft by &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_propulsion&quot; rel=&quot;nofollow noreferrer&quot;&gt;jet propulsion&lt;/a&gt;, ejecting high-velocity exhaust gasses through propelling nozzles to generate thrust that moves the aircraft.  In common use, the term refers specifically to airbreathing jet engines, which require a continuous supply of outside air in order to function.  The most-commonly-used types of jet engine are the &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt; (including the &lt;a href=&quot;/questions/tagged/geared-turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;geared-turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;geared-turbofan&lt;/a&gt;) and &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt;; the &lt;a href=&quot;/questions/tagged/ramjet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ramjet&amp;#39;&quot; rel=&quot;tag&quot;&gt;ramjet&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/scramjet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;scramjet&amp;#39;&quot; rel=&quot;tag&quot;&gt;scramjet&lt;/a&gt; are much less common, and seen almost exclusively on &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; and/or &lt;a href=&quot;/questions/tagged/hypersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;hypersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;hypersonic&lt;/a&gt; aircraft.  Other, rarer types include the &lt;a href=&quot;/questions/tagged/pulsejet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pulsejet&amp;#39;&quot; rel=&quot;tag&quot;&gt;pulsejet&lt;/a&gt;, which is unusual in that it uses pulsed (rather than continuous) combustion, and is generally only seen on unmanned aircraft, and the &lt;a href=&quot;/questions/tagged/motorjet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;motorjet&amp;#39;&quot; rel=&quot;tag&quot;&gt;motorjet&lt;/a&gt;, a very early type of jet engine which is mainly of historical interest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines are commonly found on transport-category airliners, as well as many corporate aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More information on jet engines &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;can be found on Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Related Aircraft Propulsion Tags&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/piston-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;piston-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;piston-engine&lt;/a&gt; for reciprocating engines, usually gasoline powered. Mainly used on light aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt; for turbine engines which drive a propeller to generate thrust rather than using jet propulsion.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/turboshaft&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboshaft&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboshaft&lt;/a&gt; for turbine engines which are used to provide electrical, hydraulic, and/or pneumatic power, rather than directly for propulsion.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/rocket&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rocket&amp;#39;&quot; rel=&quot;tag&quot;&gt;rocket&lt;/a&gt; for engines which carry an onboard supply of oxidizer in addition to fuel, and do not need to take in outside air.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2019-11-12T08:58:40.180" LastActivityDate="2019-11-12T08:58:40.180" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1124" PostTypeId="4" CreationDate="2014-01-17T19:21:52.490" Score="0" Body="Engines which propel aircraft via &quot;jet propulsion&quot;, i.e. by expelling high-velocity gasses (usually primarily air) through propelling nozzles." OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2018-08-16T03:02:36.947" LastActivityDate="2018-08-16T03:02:36.947" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1125" PostTypeId="2" ParentId="1120" CreationDate="2014-01-17T19:29:18.113" Score="4" Body="&lt;p&gt;As the EET is variable from flight to flight you should better say that it is dependent on specific kinds of operation or routes, which is quite the same but includes also the time before and after the flight. Flight duty time starts at check in and ends at check out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are general requirements based on the maximum allowed duty time of a crew member, which are again based on the regulations of the aviation authority of the operators country. Finally it differs from airline to airline and is regulated by the operations manual, which can of course be not less restrictive than the authority, but there are some general titles you often hear:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Captain&lt;/strong&gt; The Captain is the PIC (pilot in command) of this flight and responsible for a safe operation. He must be on station for departure and arrival. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;First Officer&lt;/strong&gt; The F/O is also found on every airliner operation. On short or medium ranges he is the 'Copilot', some airlines fly with two F/Os on long haul flights and in some portions of this flight most probably the two F/Os are in the cockpit and the captain takes a nap.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Second Officer&lt;/strong&gt; When starting at an airline, you sometimes begin as a S/O and are only alloweed to do specific tasks. So for example handling the radios during departure and arrival, or having the controls during the cruise phase.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Cruise Captain&lt;/strong&gt; Well, read the name ;) He might be a Captain and only in the function of a Cruise Captain for a specific flight, but once again, it depends on the operator.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="343" LastEditorUserId="3945" LastEditDate="2015-02-12T00:06:49.983" LastActivityDate="2015-02-12T00:06:49.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1126" PostTypeId="2" ParentId="1109" CreationDate="2014-01-17T19:57:34.947" Score="52" Body="&lt;p&gt;If you're looking for a definitive source, how about the &lt;a href=&quot;http://www.nasa.gov/centers/johnson/pdf/390651main_shuttle_crew_operations_manual.pdf&quot;&gt;Shuttle Crew Operations Manual&lt;/a&gt;. It's essentially the POH for the Space Shuttle. Secton 2.14-2 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The landing gear is deployed at 300 ± 100 feet and at a maximum of 312 knots equivalent airspeed (KEAS).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although, the targeted deploy speed was 288 KEAS according to the Normal Procedures section 5.4-7, which matches up with approximately what you see in HUD videos.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manual says the gear may take up to 10 seconds to fully deploy, but based on HUD videos (measuring the time it takes for &lt;code&gt;//GR//&lt;/code&gt; to change to &lt;code&gt;GR-DN&lt;/code&gt;), this process pretty consistently took about 6 seconds and was completed by about 70-130 feet AGL depending on the deployment altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason they deployed so late is because the shuttle was a very non-aerodynamic &quot;airplane&quot; to begin with, and lowering the gear would reduce its lift-to-drag ratio even further. However, there were non-standard procedures in place (see section 7.4-25) where, if the speed brake (a split rudder&amp;nbsp;&amp;ndash; not a wing surface) was stuck closed, they would have lowered the gear earlier in order to act as a speed brake. Note that the hydraulic system was incapable of raising the gear in-flight, so once down, it stays down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the shuttle was a &quot;glider&quot; (a generous use of that term) at landing, with no chance of going around, the gear &lt;strong&gt;absolutely must work on the first try&lt;/strong&gt;. A shuttle belly landing would have ended very bad due to its high speed and high angle of attack. In order to assure the gear would extend, there were several redundant systems in place:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The doors had a bungee-assist system which exerted 2000 pounds of force (~9 kN) on the nose wheel doors, and 5000 pounds (~22 kN) on each of the main wheel doors.&lt;/li&gt;&#xA;&lt;li&gt;The nose wheel had a pyro-assist system which fired every time the gear was deployed, and helped assure it would lock into place.&lt;/li&gt;&#xA;&lt;li&gt;The gear is normally deployed through a combination of &quot;springs, hydraulic actuators, aerodynamic forces, and gravity.&quot;&lt;/li&gt;&#xA;&lt;li&gt;However, &lt;strong&gt;&lt;em&gt;if all else fails&lt;/em&gt;&lt;/strong&gt;, and the gear does not begin to move within 1 second of issuing the command, a pyrotechnic initiator cuts the locks and forces the gear down.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So they were pretty confident it was going to work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the original procedure for deciding when to deploy the gear was based on airspeed, not altitude. However, this resulted in an inconsistent safety margin. This quote from the &lt;em&gt;Flight Procedures Handbook: Approach, Landing and Rollout&lt;/em&gt; explains it better (sorry, I don't have a link to a doc, I probably downloaded it from a &lt;a href=&quot;http://www.nasaspaceflight.com/&quot;&gt;nasaspaceflight.com&lt;/a&gt; forum a few years ago with a paid membership):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The landing gear deploy cue for STS-1 through STS-4 occurred when the velocity decelerated through &lt;strong&gt;270 KEAS&lt;/strong&gt;. This corresponded to an altitude of 200 ft on the nominal energy trajectory. Flight STS-1 followed the velocity cue procedure which, due to its much higher than expected energy, &lt;strong&gt;did not occur until an altitude of 85 ft&lt;/strong&gt;. Had the gear been deployed at 200 ft, some of that excess energy would have been dissipated. Flight STS-2 was very low on energy, reaching a maximum velocity of only 274 KEAS at 1100 ft altitude. The 270 KEAS cue occurred at 600 ft, but the actual deploy occurred at 400 ft, adding to the already existing low energy condition. Lower energy occurred since the nominal altitude for gear deploy would have occurred at 200 ft on a nominal trajectory. Flight STS-3 was high on energy, not decelerating through 270 KEAS until an altitude of 87 ft. T/D occurred earlier than expected on STS-3 and the gear was actually down and locked only a couple of seconds before first wheel contact. It was after STS-3 that altitude was selected as the gear deploy cue because it would compensate for off-nominal energy conditions, not make them worse, and still satisfy safety concerns. Downrange was also considered as a gear deploy cue, and it too, had advantages over velocity.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as the sign you are referring to, I see three possibilities:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;They were referring to the very early missions which sometimes saw very late gear deployment,&lt;/li&gt;&#xA;&lt;li&gt;They were rounding down for dramatic effect, or&lt;/li&gt;&#xA;&lt;li&gt;They simply made it up on the spot as if it were a statistic.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="6" LastEditorUserId="946" LastEditDate="2016-05-06T23:25:07.353" LastActivityDate="2016-05-06T23:25:07.353" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="1127" PostTypeId="2" ParentId="765" CreationDate="2014-01-17T21:59:16.013" Score="9" Body="&lt;p&gt;I have some of the answers:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;•Is it easier or harder to overboost a supercharger? If you do, are there waste gates?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an important point.  Waste gates, when opened, allow exhaust to bypass the turbocharger, reducing manifold pressure by slowing down the turbo.  Older turbos had manually adjusted waste gates, and even fixed waste gates.  The pilot would have to monitor boost pressure and adjust the waste gate to avoid overboosting the engine.  Newer turbos have automatic waste gates.  Superchargers, being belt or gear driven, do not have waste gates as the supercharger is not dependent on exhaust gas flow.  I do not know if they have manifold pressure releif valves in case of overpressure but I doubt they would.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a key difference in a pilot's operation of the engine is that in a manual waste gate engine, the manifold pressure gauge needs to be scanned frequently and the waste gate adjusted accordingly.   Less important in an automatic waste gate or supercharged engine.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;•Do engines with superchargers need a cool-down period before being shut off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No.  The cooldown period in turbochargers is necessary to cool down the bearings in the turbocharger after high cruise power settings.  Idling on the ground allows cooler oil to flow through the bearings, removing excess heat.  Look at your exhaust gas temperature gauge - this is the temperature of the gasses flowing through your turbocharger.  The oil present in the turbocharger bearings will &quot;coke&quot;, or turn into a solid at that temperature.  Upon landing, a slow taxi to the ramp will usually provide sufficient cool down time.  Usually!  Time this and don't forget to cool down as recommended.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Superchargers are geared to the engine (or belted) and do not use the hot exhaust as their source of power.  So even though they can get quite hot, they don't approach the heat of the exhaust gasses.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;•Any other operational differences that would be meaningful for pilots to know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not really an operational difference, but in addition to turbocharged and supercharged engines, there are also turbonormalized engines.  TN engines are turbocharged engines with their boost limited to atmospheric pressure at sea level.  Say 30 inches, not the 40 inches you might expect from a turbocharged engine.  The TN engine permits sea level performance up to a critical altitude, above which the TN engine cannot maintain sea level manifold pressure.  In other words, performance at a sea level takeoff will not be materially different from that of a naturally aspirated engine, but as you climb, the power will not decline as you climb.  So your Leadville CO takeoff will be the envy of the stock C-172 crowd.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-17T21:59:16.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1128" PostTypeId="1" AcceptedAnswerId="1168" CreationDate="2014-01-18T05:29:42.143" Score="13" ViewCount="4373" Body="&lt;p&gt;The early Boeing 737 models had wings with triple-slotted flaps that appeared to be derived from the 727. When the 737 was redesigned as the Next Generation series (dash 600 through 900), these flaps were dropped in favor of a double-slotted design. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why did Boeing choose to make this change, and what were the trade offs? Did it impact performance?&lt;/strong&gt; I had always been under the impression that early 737s were reasonably capable on shorter and rougher runways. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-20T01:43:11.253" Title="When Boeing designed the 737NG, what factors influenced the change in the flap system?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1129" PostTypeId="5" CreationDate="2014-01-18T16:57:34.497" Score="0" Body="&lt;p&gt;FAA regulations cover the aviation rules of the United States of America and territories.&#xA;This tag should be used for questions regarding requirements or limitations imposed by FAA regulations or other related guidance material.  It should &lt;strong&gt;not&lt;/strong&gt; be used for questions about contacting the FAA, filling out FAA forms, or other areas of FAA responsibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Title 14 of the United States Code of Federal Regulations (14 CFR) contains the aviation laws that the FAA is responsible for maintaining and enforcing.  14 CFR is also known as the Federal Aviation Regulations (FARs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contain rules pertaining to everything aviation-related: pilots, aircraft, maintenance, flight training, airlines and other commercial operations, the marking of obstacles and buildings, etc.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Related Tags&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-25&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-25&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-25&lt;/a&gt; Part 25 - Airworthiness Standards: Transport Category Airplanes&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-61&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-61&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-61&lt;/a&gt; Part 61 - Certification: Pilots, Flight Instructors, and Ground Instructors&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-91&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-91&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-91&lt;/a&gt; Part 91 - General flight and operating rules&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-121&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-121&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-121&lt;/a&gt; Part 121 - regulations governing U.S. scheduled air carriers&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/far-135&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;far-135&amp;#39;&quot; rel=&quot;tag&quot;&gt;far-135&lt;/a&gt; Part 135 - Operating Requirements: Commuter and On Demand Operations&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/aim&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aim&amp;#39;&quot; rel=&quot;tag&quot;&gt;aim&lt;/a&gt; - The Aeronautical Information Manual&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/usa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;usa&amp;#39;&quot; rel=&quot;tag&quot;&gt;usa&lt;/a&gt; - Questions specific to the United States (but not FAA regulations)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;See also&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;14 CFR (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dc08f5a0d35304312a716fc3a4036f37&amp;amp;tpl=/ecfrbrowse/Title14/14tab_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;eCFR.gov&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Federal Aviation Regulations (&lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Aviation_Regulations&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2020-01-20T02:40:01.680" LastActivityDate="2020-01-20T02:40:01.680" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1130" PostTypeId="4" CreationDate="2014-01-18T16:57:34.497" Score="0" Body="FAA regulations cover the aviation rules of the United States of America and its territories.&#xD;&#xA;This tag should be used for questions regarding requirements or limitations imposed by FAA regulations or other related guidance material.  It should **not** be used for questions about contacting the FAA, filling out FAA forms, or other areas of FAA responsibility." OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-02-28T05:13:10.283" LastActivityDate="2019-02-28T05:13:10.283" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1131" PostTypeId="5" CreationDate="2014-01-18T17:01:38.287" Score="0" Body="&lt;p&gt;The Federal Aviation Administration is the agency responsible for regulating and administering the United States National Airspace system.  It is a division of the United States Department of Transportation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appropriate questions for this tag would include those activities which require working directly with the FAA, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Certification&lt;/li&gt;&#xA;&lt;li&gt;Approval&lt;/li&gt;&#xA;&lt;li&gt;Letters of Authorization (RVSM, ADS-B, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Company Operations Specification approvals&lt;/li&gt;&#xA;&lt;li&gt;Manual Approvals/Acceptance/Revisions&lt;/li&gt;&#xA;&lt;li&gt;Filling out and submitting various forms (8410, 8710, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Rulemaking Process&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Related Tags&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt; - The United States Federal Aviation Regulations&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/aim&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aim&amp;#39;&quot; rel=&quot;tag&quot;&gt;aim&lt;/a&gt; - The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Information Manual&lt;/a&gt;, published by the FAA.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/usa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;usa&amp;#39;&quot; rel=&quot;tag&quot;&gt;usa&lt;/a&gt; - Questions specific to the United States (but not FAA regulations)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;See Also&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Federal Aviation Administration (&lt;a href=&quot;http://www.faa.gov&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Federal Aviation Administration (&lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Aviation_Administration&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;United States Department of Transportation (&lt;a href=&quot;http://www.dot.gov&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T17:01:38.287" LastActivityDate="2014-01-18T17:01:38.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1132" PostTypeId="4" CreationDate="2014-01-18T17:01:38.287" Score="0" Body="Use this tag for questions about the FAA itself. Questions about FAA regulations should use the faa-regulations tag. The FAA (Federal Aviation Administration) is the agency responsible for regulating and administering the United States National Airspace System." OwnerUserId="69" LastEditorUserId="6" LastEditDate="2014-04-11T03:09:45.130" LastActivityDate="2014-04-11T03:09:45.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1133" PostTypeId="5" CreationDate="2014-01-18T17:22:02.860" Score="0" Body="&lt;p&gt;EASA maintains the aviation laws for most of Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contain rules pertaining to everything aviation-related: pilots, aircraft, maintenance, flight training, airlines and other commercial operations, the marking of obstacles and buildings, etc.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Related Tags&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/easa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;easa&amp;#39;&quot; rel=&quot;tag&quot;&gt;easa&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T17:22:02.860" LastActivityDate="2014-01-18T17:22:02.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1134" PostTypeId="4" CreationDate="2014-01-18T17:22:02.860" Score="0" Body="EASA maintains the aviation laws for most of Europe.&#xD;&#xA;&#xD;&#xA;It contain rules pertaining to everything aviation-related: pilots, aircraft, maintenance, flight training, airlines and other commercial operations, the marking of obstacles and buildings, etc.&#xD;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T17:22:02.860" LastActivityDate="2014-01-18T17:22:02.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1136" PostTypeId="5" CreationDate="2014-01-18T18:00:29.560" Score="0" Body="&lt;h1&gt;See Also&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CASA (&lt;a href=&quot;http://www.casa.gov.au/&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Civil Aviation Safety Authority (&lt;a href=&quot;http://en.wikipedia.org/wiki/Civil_Aviation_Safety_Authority&quot; rel=&quot;nofollow&quot;&gt;Website&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T18:00:29.560" LastActivityDate="2014-01-18T18:00:29.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1137" PostTypeId="4" CreationDate="2014-01-18T18:00:29.560" Score="0" Body="The Australian Civil Aviation Safety Authority (CASA) is responsible for maintaining and enforcing the Australian aviation regulations.  Questions using this tag should be related to the Australian aviation regulations." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-18T18:00:29.560" LastActivityDate="2014-01-18T18:00:29.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1138" PostTypeId="2" ParentId="443" CreationDate="2014-01-18T19:01:04.183" Score="19" Body="&lt;p&gt;The first thing a pilot should do if they feel sleepy is &lt;strong&gt;&lt;em&gt;Check the CO sensor&lt;/em&gt;&lt;/strong&gt;.  Drowsiness is the first sign of Carbon Monoxide Poisoning.  Checking for CO poisoning only takes a second, and can be easily mitigated and remedied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;NOTE:&lt;/strong&gt;  Apparently a &lt;a href=&quot;http://www.sportys.com/PilotShop/product/13010&quot;&gt;Pulse Oximeter&lt;/a&gt; will &lt;em&gt;not&lt;/em&gt; indicate a CO poisoning problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully, it is &lt;em&gt;not&lt;/em&gt; CO poisoning, and they just partied to long the night before.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-03-11T14:30:34.853" LastActivityDate="2014-03-11T14:30:34.853" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1139" PostTypeId="1" AcceptedAnswerId="1145" CreationDate="2014-01-18T21:32:11.017" Score="14" ViewCount="2859" Body="&lt;p&gt;I am curious if the inverted plane in the movie Flight 2012 has anything to do with reality / emergency practices. And if it does, can you please explain the concept/ aerodynamics behind of it , or why someone would ever do that even as last resort? &lt;/p&gt;&#xA;" OwnerUserId="564" LastEditorUserId="22726" LastEditDate="2018-10-16T03:16:03.377" LastActivityDate="2018-10-16T03:16:03.377" Title="Is it possible to fly a large aircraft inverted?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;inverted-flight&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1140" PostTypeId="2" ParentId="1139" CreationDate="2014-01-18T21:39:38.057" Score="11" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Express_Flight_705&quot;&gt;FedEx 705&lt;/a&gt; underwent extreme maneuvers, even inverted flight. The captain was trying to disorient a hijacker while the first officer fought him hand-to-hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=XnNI1gi7u_U&quot;&gt;Here's a dramatization of it.&lt;/a&gt; Not sure if it's the best one but there are others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of your airfoils are designed to produce lift at 0 angle of attack (a perfectly symmetrical airfoil will not), which means that although it's more difficult than with a symmetrical airfoil, you can fly (inverted) at an angle that they will produce lift at negative angles as well. You will be inverted with the nose very high above the horizon, higher than it would be for level flight at a normal attitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, the aircraft is really not built to do invert maneuvers. Legally they must be able to withstand -1G, but that doesn't leave much room to maneuver while inverted. In reality, most aircraft are designed beyond legal limits just for safety. On top of that, just because an aircraft is rated for a certain load limit does not mean that it will catastrophically fail if that limit is exceeded. It may bend and wrinkle beyond repair, but it should take a lot more than that to fall apart. The problem is that you have no guarantee.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-01-18T21:51:47.390" LastActivityDate="2014-01-18T21:51:47.390" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1141" PostTypeId="1" CreationDate="2014-01-18T21:47:41.870" Score="19" ViewCount="7975" Body="&lt;p&gt;What should one do when done sumping a small amount of fuel during a pre-flight?  Should it be dumped on the ramp? Or is it considered necessary to find the container far away from the airplane? Is it considered safe to dump it right back into the plane if it is uncontaminated?&lt;/p&gt;&#xA;" OwnerUserId="188" LastEditorUserId="1467" LastEditDate="2018-05-04T12:18:32.177" LastActivityDate="2018-05-04T12:18:32.177" Title="What should I do with fuel drained from the sumps during preflighting?" Tags="&lt;preflight&gt;&lt;fuel&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1142" PostTypeId="2" ParentId="1141" CreationDate="2014-01-18T22:03:40.423" Score="1" Body="&lt;p&gt;I always put it back in the tank if it's not contaminated. Even if it is I'll put as much as I can back in. A few millimeters of water is not going to do anything when it would take almost a gallon of it just to reach the fuel pickup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for dumping, I've heard the EPA has been known to watch airports with heavy flight activity. They'll write your tail number down and send you a fine. Some states don't have any laws about it, though. I would save all the fuel I could, honestly. You can filter out uncontaminated fuel and reuse it. I know that's not really plausible if you're not in a hangar, though.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-18T22:03:40.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1144" PostTypeId="2" ParentId="1141" CreationDate="2014-01-19T01:33:00.050" Score="4" Body="&lt;p&gt;You &lt;em&gt;should&lt;/em&gt; dispose of it in a fuel disposal container, if your airport has them (and many states require it). Barring that, the best option is a type of fuel strainer called a GATS jar that has a built-in filter to catch any particulates. If you pull a sample in a GATS jar that comes back &quot;dry&quot; you just unscrew the filter and put it back in the tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you pull water, you should dispose of it in a way that doesn't involve dumping it on the ground. Either put it in a disposal container (lobby your airport or FBO to install them if they don't exist) or your own labeled gas can and use it for your lawnmower or something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have no other option, try to avoid pouring it in a puddle on the ground. Toss it in an arc so it covers a large area and can evaporate as quickly as possible&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-19T01:33:00.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1145" PostTypeId="2" ParentId="1139" CreationDate="2014-01-19T01:33:35.060" Score="19" Body="&lt;p&gt;In the movie Flight (2012), Captain Whittaker (Denzel Washington) does not explain why he deliberately inverted his aircraft, but the obvious inference is: since the horizontal stabilizer has slipped off its jackscrew and become jammed into a descent angle beyond the authority of the elevators to correct, in inverted flight this would push the nose far above the horizon and result in either a climb or a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this attitude, Whittaker would have been pulling back on the yoke to prevent the stall.  In the movie, this worked.  The aircraft was still not under control, but was no longer diving and overspeeding.  Suddenly rolling the aircraft upright in the last seconds before contact with terrain is the unrealistic part.  A hot fighter jet might accomplish this but the roll rate of a passenger jet is too slow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The movie's flight emergency is based mostly on the crash of Alaska Airlines flight 261 on January 31, 2000.  In that incident, the pilots experienced a jammed horizontal stabilizer with uncontrollable dive, and inverted their MD-80 to arrest their descent.  Unfortunately in real life neither flying officer was stuffed to the gills with booze and coke: the maneouver failed and the aircraft crashed with no survivors.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-01-19T01:33:35.060" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1146" PostTypeId="2" ParentId="1141" CreationDate="2014-01-19T01:53:54.423" Score="13" Body="&lt;p&gt;The FAA issued an Aviation Safety Program publication called &lt;a href=&quot;http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=6846&quot;&gt;All About Fuel&lt;/a&gt; which talks about fuel preflight, including sumping fuel.  It contains the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;&lt;strong&gt;Preflight Action&lt;/em&gt;&lt;/strong&gt;     As pilot in command, you have the responsibility to determine that your aircraft is properly serviced.&#xA;  Check your aircraft before each flight and be sure you have the&#xA;  correct type of fuel. This practice may save your life! Take the time&#xA;  to inspect your aircraft thoroughly. Good preflight procedures:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Be sure all of the fuel and oil tank caps and covers are installed and secured properly after you visually check the fluid level.  &lt;/li&gt;&#xA;  &lt;li&gt;Observe the color and odor of the fuel as you check the tank.  &lt;/li&gt;&#xA;  &lt;li&gt;Draw a generous sample of fuel from each sump and screen drain into a transparent container. Check for the presence of water, dirt, rust&#xA;  or other contaminants. Unless you have the proper kind of fuel tester&#xA;  (e.g., GATS jar with intact fuel strainer), do not attempt to save the&#xA;  fuel drained from the sumps by pouring it back into the tank. Note: If&#xA;  you are not equipped to safely pour the drained fuel back into the&#xA;  tank, please be sure to dispose of it in accordance with EPA&#xA;  regulation.  &lt;/li&gt;&#xA;  &lt;li&gt;Check that each fuel tank vent is clear of restrictions; i.e., dirt, ice, snow, bent or pinched tubes, etc.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Any FBO that sells fuel should have a way to dispose of it.  Some of them make it more obvious than others by putting sump barrels out on the ramp, but ask them what to do with it before you go out to the airplane and they should be able to help you out.  For environmental reasons, you definitely shouldn't dump it on the ground, because even if it does evaporate, it will come down somewhere.  At some airports you can even get in a lot of trouble (and have to pay a big fine) by dumping fuel on the ramp.  Don't take a chance!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-19T01:53:54.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1147" PostTypeId="1" AcceptedAnswerId="1148" CreationDate="2014-01-19T01:58:46.370" Score="33" ViewCount="2597" Body="&lt;p&gt;Another enthusiast question. I watch a lot of the National Geographic Channel's &quot;Air Crash Investigation&quot;, for better or worse, and it seems accident investigators make tremendous use of the Cockpit Voice Recorder &quot;CVR&quot; and Flight Data Recorder &quot;FDR&quot; to determine the chain of events leading up to- or the root cause of an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the more recent episodes of ACI (Season 12 Ep. 13) was about &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Air France 447&lt;/a&gt;, the worst disaster in French aviation history. That investigation spent &lt;em&gt;two years and $50 million just locating the CVR and FDR&lt;/em&gt; which were ultimately found resting 4 kilometers beneath the mid-Atlantic. Even after the recovery, there were concerns one of the drives had failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That ACI episode also mentioned that the Airbus A330-203 in that accident came equipped with a system which periodically transmitted maintenance data to a remote Airbus location in Paris to alert ground crews of possible maintenance issues with inbound aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that Airbus already uses similar technology for maintenance data (and I think I recall hearing Boeing does too), I was wondering if either Airbus, Boeing, or the FAA, plan to facilitate or mandate that the CVR and FDR record to the cloud or a remote location either in lieu of or in addition to the physical devices installed in commercial aircraft. I would think this would be an accident investigator's dream come true, with almost instant access to vital investigative information, while drastically reducing instances of going without these crucial tools when the physical devices are unrecoverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, does anyone in the know have any idea if there are plans for CVR and FDR data to be transmitted and recorded to the cloud or a remote location?&lt;/p&gt;&#xA;" OwnerUserId="363" LastEditorUserId="22726" LastEditDate="2020-05-25T22:07:27.300" LastActivityDate="2020-05-25T22:07:27.300" Title="Could the CVR and FDR record to the cloud?" Tags="&lt;faa-regulations&gt;&lt;avionics&gt;&lt;accidents&gt;&lt;flight-recorders&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1148" PostTypeId="2" ParentId="1147" CreationDate="2014-01-19T02:42:31.110" Score="18" Body="&lt;p&gt;The basic problem with transmitting CVR &amp;amp; FDR data to the ground from flight is the sheer amount of data that is generated by today's sophisticated airplanes.  There are hundreds of parameters being recorded many times per second plus the voice channels.  Today's airliners &lt;a href=&quot;http://www.computerworlduk.com/news/infrastructure/3433595/boeing-787s-create-half-terabyte-of-data-per-flight-says-virgin-atlantic/&quot;&gt;record 500 GB of data on each flight&lt;/a&gt;.  Take this and multiply it by the thousands of airplanes that are in flight at any given moment, and you can see that there would need to be a lot of bandwidth available for all of it to be transmitted wirelessly.  There would also need to be a world-wide standard developed and hardware deployed so that an airplane can transmit the data no matter where they are.  Airplanes operating in remote locations would have to use satellites, which are relatively low speed and expensive to deploy/maintain/operate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, it just isn't practical with today's technology.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-19T02:48:25.290" LastActivityDate="2014-01-19T02:48:25.290" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1150" PostTypeId="1" AcceptedAnswerId="1151" CreationDate="2014-01-19T06:35:26.873" Score="14" ViewCount="2160" Body="&lt;p&gt;Let's assume that I'm on a check-ride and my next requirement is to perform a short-field landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm coming in for landing and it's obvious I'm not going to hit my mark, can I perform a go-around and try again? Would that be considered a fail?&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="19" LastEditDate="2017-03-12T21:19:04.533" LastActivityDate="2017-03-12T21:19:04.533" Title="Will I fail a check-ride if I do a go-around for a short-field landing?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;checkride&gt;&lt;designated-examiner&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1151" PostTypeId="2" ParentId="1150" CreationDate="2014-01-19T06:49:15.513" Score="22" Body="&lt;h2&gt;In general, you get one free go-around.&lt;/h2&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;First of all, any checkride which involves short-field landings probably also involves demonstrating go-arounds.  &lt;strong&gt;If you don't do one on your own, your examiner will have to ask to see one later.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Going around when it's obvious you're not going to make your point demonstrates good judgment.&lt;/strong&gt;  It shows that you're not going to try to force the airplane into an unsafe situation just to hit your mark.  If the runway you're landing on really &lt;em&gt;is&lt;/em&gt; a short field, continuing the landing attempt would not only be a bad idea, it would be unsafe, and the examiner would be correct in taking the controls from you, as well as failing you.  If the runway is long and you're simulating a short field landing, the same applies.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;If you go around on a short-field landing and then go around on the next one as well, the examiner is going to start to wonder whether you really know what you're doing.&lt;/strong&gt;  Let's face it, it should not take you three tries to get properly set up for a short field landing, unless perhaps if the day is remarkably turbulent or there is a strong gusty crosswind.  If that's the case, though, why in the world did you decide to take your checkride in those conditions?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-19T06:49:15.513" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1152" PostTypeId="1" AcceptedAnswerId="1153" CreationDate="2014-01-19T10:38:32.453" Score="27" ViewCount="4472" Body="&lt;p&gt;I'm simplifying here, but every introduction to flying shows us that the profile of a wing leads to lower pressure on the upper side of the wing, hence the wing and the plane attached to it will be pulled up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does that explain a plane flying inverted? If the explanation was right, the plane would pull itself towards earth.&lt;/p&gt;&#xA;" OwnerUserId="133" LastEditorUserId="69" LastEditDate="2014-01-19T13:13:00.353" LastActivityDate="2021-02-10T22:45:17.793" Title="If the profile of a wing pulls a plane up, why can planes fly inverted?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1153" PostTypeId="2" ParentId="1152" CreationDate="2014-01-19T11:44:59.677" Score="25" Body="&lt;p&gt;Normally, an airfoil is optimized for best lift/drag (L/D) efficiency for a certain flight profile (usually a compromise). Since most of the time for most aircraft inverted flight is &lt;em&gt;not&lt;/em&gt; an issue, you get an airfoil that is optimized for upright flight, and this is best achieved with asymmetric geometries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, depending on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Angle_of_attack&quot;&gt;angle of attack&lt;/a&gt; any airfoil can (and will) generate &quot;negative&quot; lift, only much less efficiently so, than for the optimized regime,  resulting in increased drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The desired angle of attack for conventional aerodynamically controlled aircraft is maintained by the elevator. For symmetric airfoils commonly used for aerobatic planes, the performance for upright and inverted flight is quite similar. For 99% of all other airfoils inverted flight will work up to a certain point, depending on the available power, CG, the maximum lift and rudder forces availabe before stall. As a result, for some aircraft, a stable inverted flight cannot be maintained, while for others it could be (but with varying penalty to performance, stall speed etc). The aerodynamical possiblity of inverted flight is of course limited by structural and other considerations.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2014-01-19T13:49:40.897" LastActivityDate="2014-01-19T13:49:40.897" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1154" PostTypeId="2" ParentId="1141" CreationDate="2014-01-19T12:30:28.513" Score="5" Body="&lt;p&gt;Personally, I have a gas powered tug to pull/push my plane with. My tug is only certified for mogas, but I pour all of my avgas samples into it... I've &lt;em&gt;never&lt;/em&gt; had to fuel it any other way.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-01-19T12:30:28.513" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1155" PostTypeId="1" AcceptedAnswerId="1165" CreationDate="2014-01-19T13:33:35.400" Score="11" ViewCount="1191" Body="&lt;p&gt;I understand that for an amateur-built that you are required to build at least 51% of the aircraft yourself, but how can there be kits which appear practically completed, just some quick assembly jobs? Could someone explain how this 51% rule works, and what is this percentage based on?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="97" LastEditDate="2014-01-28T17:40:11.030" LastActivityDate="2019-10-24T10:30:58.727" Title="How exactly is the 51% rule applied for amateur-built aircraft?" Tags="&lt;aircraft-design&gt;&lt;amateur-experimental&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1156" PostTypeId="2" ParentId="1152" CreationDate="2014-01-19T13:58:05.167" Score="12" Body="&lt;p&gt;This relation between a wing's curvature and a pressure difference on both sides is often part of the 'equal transit time' explanation; air on the curved side has to traverse a longer distance in the same amount of time, therefore goes faster, which leads to a lower pressure. This explanation is very common and completely wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In normal flight, pitching the nose up causes the aircraft to climb because the wings meet the air at a steeper angle; the lift increases. It makes sense that rotating the wings in the opposite direction decreases lift. In fact, point the nose down far enough and the wings will produce no lift at all. Beyond that, the generated lift becomes negative and the wings will start to pull the aircraft down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During our hypothetical manoeuvre, our attitude has varied by about 10°. That's not exactly flying upside down yet, the curved side of the wings were on top the entire time. Whether or not the lift was pointing up as well, depended on the angle at which the wings meet the air, the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true for inverted flight. If we find ourselves at an attitude where the wings are pulling us down, we raise the nose. At first, the downward lift will disappear and at higher angles of attack, start pointing up and grow larger. At sufficient airspeeds and angles of attack, we have enough lift to maintain altitude upside down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why do wings need to be curved at all? They don't. Flat wings also provide lift at non-zero angles of attack and are perfectly usable, but not very efficient. Properly shaped airfoils create more lift and less drag. To find out why, consult a more accurate explanation of how planes really fly.&lt;/p&gt;&#xA;" OwnerUserId="67" LastActivityDate="2014-01-19T13:58:05.167" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1157" PostTypeId="1" AcceptedAnswerId="1163" CreationDate="2014-01-19T14:10:28.953" Score="24" ViewCount="3864" Body="&lt;p&gt;When I was learning for my license, one of the first diagrams I remember was about the wing profile. The air going around the wing and on the upper side it has to travel a longer way, thus generating lower pressure and bang, plane is flying.&#xA;Same explanation already back at school.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See my other question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1152/if-the-profile-of-a-wing-pulls-a-plane-up-why-can-planes-fly-inverted/1156?noredirect=1#1156&quot;&gt;if the theory was right, why can planes fly inverted?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here's the follow up: why is this wrong theory so popular and still part of books?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it make sense to teach students how a wing really works? I mean just look at any RC plane meeting - you'll be amazed what &lt;a href=&quot;http://www.youtube.com/watch?v=0rJnXZsrMjU&quot; rel=&quot;nofollow noreferrer&quot;&gt;weird designs are capable of flying&lt;/a&gt; if there's enough engine power. &lt;/p&gt;&#xA;" OwnerUserId="133" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2019-10-02T15:27:35.813" Title="Why is the wrong explanation of &quot;air travels a longer distance and creates a lift&quot; so popular?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1159" PostTypeId="2" ParentId="1150" CreationDate="2014-01-19T17:11:42.917" Score="15" Body="&lt;p&gt;In short, &lt;strong&gt;No&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I messed up both my short field, and soft-field landings.&lt;br&gt;&#xA;I properly called and executed a go-around, and hit the landings on the second tries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The examiner passed me, and gave me credit for executing properly when the landing couldn't be saved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the important thing that he called out after the flight is that a Private Pilot's License is a &quot;License to Learn&quot; in a very literal sense.   You are not required to execute every maneuver perfectly to pass.  You are required to execute to a tolerance such that the safe outcome of the flight is not in question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All instructors and examiners understand that learning is a life-long process, and recent events have repeatedly shown us how even the most experienced commercial pilots still need improvement on some skills.  As long as you demonstrate that you can control the plane, exercise good judgement, and keep everything safe, you're likely to pass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The corollary to this is that once you have your license, you cannot believe that you are &lt;em&gt;done&lt;/em&gt; and qualified.   Having a PPL just means you have a &lt;strong&gt;&lt;em&gt;ton&lt;/em&gt;&lt;/strong&gt; more to learn, but you can practice and learn a lot of that on your own, without an instructor constantly next to you.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-01-19T17:49:57.497" LastActivityDate="2014-01-19T17:49:57.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1160" PostTypeId="2" ParentId="1157" CreationDate="2014-01-19T17:16:03.737" Score="20" Body="&lt;h2&gt;Wouldn't it make sense to teach students how a wing really works?&lt;/h2&gt;&#xA;&lt;p&gt;&lt;strong&gt;No, not really.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Ask any (good) CFI and they'll tell you that there are certain topics that a student really needs to understand properly.  Examples:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What's a stabilized approach and how do you fly one?  (A disappointing number of students tell me it means holding the same airspeed all the way down)&lt;/li&gt;&#xA;&lt;li&gt;Why do we clear the prop area?  (You'd think this would be too simple to screw up, but there's been more students than I've got fingers on my throttle hand who haven't yelled &amp;quot;clear!&amp;quot; &lt;em&gt;until they're already cranking the engine&lt;/em&gt;.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;And so on.&lt;/p&gt;&#xA;&lt;p&gt;How a wing &lt;em&gt;really&lt;/em&gt; works is not one of these topics - the consequences of misunderstanding a stabilized approach are that you screw it up and your landings are terrible (or even dangerous).  The consequences of misunderstanding prop safety are that someone loses a hand or dies.  The consequences of misunderstanding how a wing generates lift are...well...the wing keeps flying anyway.&lt;/p&gt;&#xA;&lt;p&gt;Now, if the student is an aerospace engineer, they'll need to know the real story, but for a pilot, they can continue in their ignorance for their entire career and never be negatively affected (unless they meet an aerospace engineer in a bar and get into a fight).&lt;/p&gt;&#xA;&lt;p&gt;To extend the point, I myself tell students that to &lt;em&gt;properly&lt;/em&gt; understand GPS, you need to get into the theory of relativity, but for a functional but incorrect understanding, you can think of it as &amp;quot;DME-in-space&amp;quot;.  &lt;strong&gt;It's very wrong on several levels, but it's enough to satisfy the needs of that category of student - same as the wing pressure-differential explanation.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-19T17:16:03.737" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1161" PostTypeId="2" ParentId="1150" CreationDate="2014-01-19T17:25:32.403" Score="12" Body="&lt;p&gt;&lt;strong&gt;No, you shouldn't fail&lt;/strong&gt; &lt;em&gt;if you're going around for a valid reason&lt;/em&gt; and the go-around is well executed. If you're well prepared, the way you operate on the checkride should be how you would operate if the examiner was &lt;em&gt;any other passenger&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you take a look at the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot;&gt;Practical Test Standards&lt;/a&gt; for &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot;&gt;Airplane (FAA-S-8081-14B)&lt;/a&gt;, there are a couple of areas that help answer your question. The biggest one is that Normal &amp;amp; Crosswind Landing (Task B, p. 43) includes this as a subtask:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the applicant [...] 11. Executes a timely go around decision when the approach cannot be made within the tolerances specified above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...while Go-Around/Rejected Landing (Task L, p. 50) includes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the applicant [...] 2. Makes a timely decision to discontinue the approach to landing. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That said, it's interesting to note that &lt;em&gt;none of the other landing tasks&lt;/em&gt; include the &quot;timely go around decision&quot; subtask from Task B, so this possibly gives examiners a bit of leeway. You should be executing the go around as early as possible, at the soonest point you think that your setup is not correct. If you're too high on base, or you're not descending enough, or you forget to get your flaps in at the right time - reset the maneuver! And when you execute your go-around, make sure it is well executed (and to the PTS standards).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, a lot of your checkride comes down to the criteria under &lt;strong&gt;Examiner Responsibility&lt;/strong&gt; (p. 10):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;Satisfactory Performance&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;Satisfactory performance to meet the requirements for certification is based on the applicant’s ability to safely:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;perform the Tasks specified in the Areas of Operation for the certificate or rating sought within the approved standards;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;demonstrate mastery of the aircraft by performing each Task successfully&lt;/strong&gt;;&lt;/li&gt;&#xA;  &lt;li&gt;demonstrate satisfactory proficiency and competency within the approved standards;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;demonstrate sound judgment and exercises aeronautical decision-making/risk management&lt;/strong&gt;; and&lt;/li&gt;&#xA;  &lt;li&gt;demonstrate single-pilot competence if the aircraft is type certificated for single-pilot operations.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Between &quot;mastery of the aircraft...&quot; and &quot;demonstrate sound judgment&quot;, there is a wide range left up to the examiner. Most examiners, I feel, are pretty sympathetic to students' nerves and the day's conditions. If it takes you one (&lt;em&gt;maybe&lt;/em&gt; two) go-arounds to nail your short-field landing, and the rest of the flight went well, you're set. If they have to take over because you're constantly going around... you're going to get to try again later after some more practice.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-19T17:52:16.440" LastActivityDate="2014-01-19T17:52:16.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1162" PostTypeId="2" ParentId="1150" CreationDate="2014-01-19T18:10:02.383" Score="10" Body="&lt;p&gt;I did a go around on the short field for my PPL checkride. I was floating too much and even with a slip and s-turn I couldn't make it. So I went around and tried again. On my second try I turned base further downwind so I had a long final. Then I dragged it in for a spot on landing. The DE asked me if I knew why I was floating so much and I told him I had a tailwind but on the surface the windsock showed totally calm. He said I was right and that he calculated a 15 knot tailwind while I was flying. There was a lot of other traffic in the pattern so I didn't have the option of switching sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DE told me that the go around was the right thing to do because he can't fail me for my landing if I don't land. He said if I was doing a lot of go-arounds for no reason that would be a problem, but otherwise a go around isn't a landing.&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2014-01-19T18:10:02.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1163" PostTypeId="2" ParentId="1157" CreationDate="2014-01-19T18:15:13.733" Score="30" Body="&lt;p&gt;Long story short is that both Newton's third law and the Bernoulli's effect are two different ways of explaining the same phenomena. Accurate equations have been written to explain both. Newton's third law, the air being forced down and forcing the airplane up, is actually the &lt;em&gt;effect&lt;/em&gt; of lift though not the cause. The &lt;em&gt;cause&lt;/em&gt; of lift is the change in pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The falsehood that is taught is usually that the two little air particles actually meet up at the same point downstream at the trailing edge of the wing at the same time. This is completely false. In fact, if you were to actually track two air particles, one over the top, and one across the bottom, the one going over the top of the wing will probably arrive much sooner than the one on the bottom! [Even though the distance IS longer] It picks up that much speed. Also they don't actually really meetup again afterwards at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real pivotal relation (which I learned in my Advanced Aerodynamics class at ERAU using John. D. Anderson's book &lt;em&gt;&lt;a href=&quot;http://books.google.com/books/about/Introduction_to_Flight.html?id=uMV5cgAACAAJ&quot;&gt;Intro to Flight&lt;/a&gt;&lt;/em&gt;) is the Kutta-Joukowsky theorem. Taking the time to explain this to a Private Pilot student would probably be a waste of your time and theirs but I will sum it up here anyway to be fair to the question. I will assume incompressible flow because after about Mach .3&amp;lt; it starts to get more complicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Kutta-Joukowsky theorem takes the integral of velocity times the cosine of the incremental angle of the distance along the closed curve. This is a quantity called circulation. The lift equation is then formed as lift equals density (altitude basically) times velocity times circulation. So if you really want get in-depth here is an &lt;a href=&quot;http://web.mit.edu/2.016/www/handouts/2005Reading4.pdf&quot;&gt;article from MIT&lt;/a&gt; that explains &lt;em&gt;potential flow theory&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you will find is that the &lt;em&gt;cause&lt;/em&gt; of lift is indeed directly related to Bernoulli's principle in that the change in pressure is what creates the lift. &lt;strong&gt;However&lt;/strong&gt; it has nothing to do with particles meeting up at the trailing edge because they never really do meet up. This doesn't discount Newton's third law either: lift can be explained that way but it is the &lt;em&gt;effect&lt;/em&gt; of lift, not the actual cause. And yes, like you mentioned, even a flat-plate for example can create lift when angled right in a wind tunnel. &lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="275" LastEditDate="2014-01-24T02:26:42.787" LastActivityDate="2014-01-24T02:26:42.787" CommentCount="26" ContentLicense="CC BY-SA 3.0" />
  <row Id="1164" PostTypeId="1" CreationDate="2014-01-19T18:57:09.697" Score="5" ViewCount="561" Body="&lt;p&gt;Anecdotally I have heard of various things that I can do to make steel brakes last longer before they have to be replaced, and they make sense but how much does it really help?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things that I have heard: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Land at the minimum recommend speed&lt;/li&gt;&#xA;&lt;li&gt;Use maximum reverse thrust (if you have it)&lt;/li&gt;&#xA;&lt;li&gt;Delay braking after landing (if on a sufficiently long runway) to allow slowing before brake application&lt;/li&gt;&#xA;&lt;li&gt;Various taxi techniques (taxi on one engine, don't ride the brakes, but instead build up speed and then brake to slow down.  Rinse and repeat.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there any studies that have been done to show how much these things help and whether or not it makes a measurable difference?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="100" LastEditDate="2020-05-04T08:56:42.723" LastActivityDate="2020-05-04T08:56:42.723" Title="How much does pilot technique affect brake life?" Tags="&lt;pilot-technique&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1165" PostTypeId="2" ParentId="1155" CreationDate="2014-01-19T22:33:11.550" Score="6" Body="&lt;p&gt;The requirement which states that &lt;strong&gt;at least 51% of the tasks needed to make the aircraft airworthy must be accomplished by amateurs&lt;/strong&gt; is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.3.9.8.11.14&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 21.191(g)&lt;/a&gt;. Presumably this would exclude finishing items like paint, some instruments, avionics, interiors, etc., as those are items which in most cases are not required for airworthiness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has &lt;a href=&quot;http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/kits/&quot; rel=&quot;nofollow noreferrer&quot;&gt;several checklists&lt;/a&gt; which inspectors use to evaluate the &quot;major portion&quot; requirement. Homebuilders thoroughly document the construction process (or at least, they should!) in a builder's log; a lot of these tend to turn into massive photoblogs. &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99737&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 20-27G contains guidance on what this documentation should look like and contain&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;two weeks to taxi&quot; builder-assist programs that exist out there generally get the basics working, but they certainly aren't &quot;two weeks to flight&quot;. Most manufacturers carefully calculate the amount of work they can offer as a kit, based on the number of tasks remaining for the builder to finish. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not a builder, so I can't say for sure, but I understand most of the advantage to these programs is &lt;em&gt;not&lt;/em&gt; that somebody is helping you - it's that they can supply tools, jigs, and a lot of behind-the-scenes support like organizing your workflow and providing answers to questions with no turnaround time. &lt;strong&gt;They're not there building the plane with you; they're there to make it possible for you to build the plane more quickly&lt;/strong&gt;... if that distinction makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.eaa.org/eaa/aircraft-building/building-your-aircraft/getting-started/the-51-percent-rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;EAA also offers a pretty good FAQ for the 51-percent rule&lt;/a&gt;, which I admit to paraphrasing here and there!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="5568" LastEditDate="2019-10-24T10:30:58.727" LastActivityDate="2019-10-24T10:30:58.727" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1166" PostTypeId="1" AcceptedAnswerId="1175" CreationDate="2014-01-19T23:46:53.077" Score="16" ViewCount="4218" Body="&lt;p&gt;I get that standard brakes and carbon fiber brakes are made out of two different materials, but some of the procedures are different between them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, they recommend &quot;heavy&quot; braking on landing (even if it isn't required) in order to &lt;em&gt;prevent&lt;/em&gt; brake wear.  Why is that?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What other differences are there between them that a pilot needs to know about before flying an aircraft with carbon fiber brakes?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-06-11T06:40:24.550" Title="Why is &quot;heavy braking&quot; recommended in an aircraft with carbon fiber brakes in order to prevent brake wear? That seems backwards!" Tags="&lt;aircraft-design&gt;&lt;pilot-technique&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1167" PostTypeId="1" AcceptedAnswerId="1174" CreationDate="2014-01-20T00:19:46.920" Score="10" ViewCount="13659" Body="&lt;p&gt;My only detailed experience with carburetors is in aircraft. I'm pretty familiar with the principles behind float-type carbs, but I recently saw a schematic for a &quot;downdraft carburetor&quot; with a choke valve. This got me curious, so I did a little research and found that what I'm used to is an &quot;updraft carburetor&quot;, and that (according to wikipedia) they &lt;a href=&quot;http://en.wikipedia.org/wiki/Carburetor#Principles&quot; rel=&quot;noreferrer&quot;&gt;fell out of fashion&lt;/a&gt; in the automotive industry in the &lt;strong&gt;1930s&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why is the updraft carburetor design so prevalent in aviation?&lt;/strong&gt; Does an updraft carb actually have a choke valve?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Images below to provide a little context for those of us who are not engine experts!&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Typical aviation carb:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PXTpE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PXTpEm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Typical downdraft automotive carb:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ABtyX.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ABtyXm.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-20T05:59:58.897" LastActivityDate="2016-12-16T00:22:04.563" Title="Why are updraft carburetors standard in aviation?" Tags="&lt;piston-engine&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1168" PostTypeId="2" ParentId="1128" CreationDate="2014-01-20T01:43:11.253" Score="10" Body="&lt;p&gt;One of the biggest differences that you will see between the flaps on the two is that the NG (photo on the right) has continuous span flaps while the classic has split inboard and outboard flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n7pg6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n7pg6m.jpg&quot; alt=&quot;737 Classic Flaps&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/OhDoE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OhDoEm.jpg&quot; alt=&quot;737NG Flaps&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combined with the longer wing on the NG, this gives the new flaps more surface area, so they don't need to be quite as effective.  Overall, the NG actually has better performance than the classic, mainly because of the redesigned wing which is 25% larger and has winglets; both of which help out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though the performance is better with comparable triple-slotted flaps, the double-slotted flaps are lighter (which helps with overall aircraft performance) and have fewer moving parts.  This makes them more reliable and they require less maintenance.  Most new aircraft designs are moving to either double or even single slotted flaps because of this simpler design and the fact that today's runways don't require the extra performance that would be gained by the more complicated flaps.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Photo Credits&lt;/strong&gt;:&lt;br&gt;&#xA;&lt;a href=&quot;http://farm8.staticflickr.com/7131/7448379360_c2cf935b68_o.jpg&quot; rel=&quot;noreferrer&quot;&gt;737 Classic Flaps&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://i1.ytimg.com/vi/PTdnMDxehf0/maxresdefault.jpg&quot; rel=&quot;noreferrer&quot;&gt;737NG Flaps&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-20T01:43:11.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1169" PostTypeId="1" AcceptedAnswerId="1170" CreationDate="2014-01-20T02:07:55.717" Score="15" ViewCount="1640" Body="&lt;p&gt;FAR 61.57 (a) requires that one must make 3 takeoffs and landings within the preceding 90 days in order to carry passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does a &quot;crash landing&quot; count for the 61.57 currency? By &quot;crash landing&quot; I mean a landing on which an incident/accident occurs under the NTSB definitions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if I'm in the circuit to gain 61.57 currency, and on my 3rd landing attempt, I crash the aircraft into a tree well short of the runway. Would I then be allowed to go rent another aircraft and carry a passenger?&lt;/p&gt;&#xA;" OwnerUserId="48" LastEditorUserId="69" LastEditDate="2014-01-20T04:07:54.910" LastActivityDate="2014-01-20T04:07:54.910" Title="Can a &quot;crash landing&quot; be used for FAR 61.57 currency?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;accidents&gt;&lt;currency&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1170" PostTypeId="2" ParentId="1169" CreationDate="2014-01-20T03:40:10.370" Score="13" Body="&lt;p&gt;As far as I can find, the FAA doesn't define the term &lt;em&gt;landing&lt;/em&gt; so it could be argued either way.  The &quot;typical&quot; &lt;a href=&quot;http://www.merriam-webster.com/dictionary/landing&quot;&gt;definition of landing&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;1:&lt;/strong&gt; an act or process of one that lands; especially :  a going or bringing&#xA;  to a surface (as land or shore) after a voyage or flight&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That definition doesn't say that it has to be &quot;controlled&quot; or that the airplane has to be usable again!  Even if you decide that it wasn't a &quot;successful landing&quot;, you could always get your third landing later if you are still allowed to fly, and then carry the passengers.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So this brings us to the second part of your question:  Are you allowed to fly after an accident?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you had an accident (as defined by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title49/49cfr830_main_02.tpl&quot;&gt;49 CFR 830&lt;/a&gt;) you must immediately notify the NTSB of the accident.  Once you do that, you have 10 days to file the required report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point, you still have a valid pilot license and can legally fly another airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chances are however, that you will be receiving a certified letter from the local FSDO requiring a &lt;em&gt;reexamination&lt;/em&gt; in order to keep your license because your competence has been called into question.  If you don't call them to make an appointment, they will start the process to suspend your certificate.  During this time, you can also continue to fly because you still have a valid license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA can also use their emergency authority to immediately suspend your license if they feel that it is warranted.  This can be appealed to the NTSB board if you feel that it isn't justified, and they have up to five days to respond.  At this point you are not allowed to fly pending the response from the board.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This, and a lot more information can be found on &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/FAA-Enforcement/FAA-Enforcement.aspx&quot;&gt;AOPA's FAA Enforcement Webpage&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-20T03:40:10.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1171" PostTypeId="1" AcceptedAnswerId="1173" CreationDate="2014-01-20T03:49:43.147" Score="7" ViewCount="2609" Body="&lt;p&gt;Aircraft categories include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airplane&lt;/li&gt;&#xA;&lt;li&gt;Rotorcraft&lt;/li&gt;&#xA;&lt;li&gt;Glider&lt;/li&gt;&#xA;&lt;li&gt;Lighter than air&lt;/li&gt;&#xA;&lt;li&gt;Powered lift&lt;/li&gt;&#xA;&lt;li&gt;Powered parachute&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;strong&gt;Weight-shift-control&lt;/em&gt;&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm familiar with all of these &lt;em&gt;except&lt;/em&gt; for weight-shift-control.  What are they??&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="609" LastEditDate="2015-01-11T03:35:10.970" LastActivityDate="2015-01-11T03:35:10.970" Title="What is a weight-shift-control category aircraft?" Tags="&lt;flight-controls&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1172" PostTypeId="2" ParentId="1167" CreationDate="2014-01-20T05:38:35.253" Score="9" Body="&lt;p&gt;You get a lot of answers about shorter intake manifolds, less probability of flooding the cylinders if your carb floods, and many other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But to me, it comes down to one big issue: visibility. You need to mount your engine high enough that you have adequate prop clearance without having to have long, heavy landing gear struts. So you mount your engine fairly high on the airframe. Now do you want to have a carburetor sitting on top of that engine directly in the pilot's field of view? Why would you do that when you have all that space down below the engine?&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-01-20T19:45:20.127" LastActivityDate="2014-01-20T19:45:20.127" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1173" PostTypeId="2" ParentId="1171" CreationDate="2014-01-20T05:40:07.483" Score="7" Body="&lt;p&gt;Basically, it's &lt;a href=&quot;http://goo.gl/Ux9ARd&quot; rel=&quot;nofollow noreferrer&quot;&gt;a powered hang glider&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/s5OjT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Weight-shift control (WSC) aircraft means a powered aircraft with a framed pivoting wing and a fuselage controllable only in pitch and roll by the pilot’s ability to change the aircraft’s center of gravity (CG) with respect to the wing. Flight control of the aircraft depends on the wing’s ability to deform flexibly rather than on the use of control surfaces. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;— &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA H-8083-5 Weight Shift Control Aircraft Flying Handbook&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're commonly called &quot;trikes&quot; and are literally big delta-wing hang gliders with a lot more structure and an engine. &lt;a href=&quot;http://www.youtube.com/watch?v=znP4T45iGqY&quot; rel=&quot;nofollow noreferrer&quot;&gt;Check out a cockpit video of one in flight!&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-20T18:36:00.240" LastActivityDate="2014-01-20T18:36:00.240" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1174" PostTypeId="2" ParentId="1167" CreationDate="2014-01-20T06:02:43.027" Score="10" Body="&lt;p&gt;I can think of three reasons to use an updraft carburetor in a single-engine GA airplane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anti-flooding:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The float-bowl regulator in your carburetor is cheap and simple, but it is far from perfect under all conditions.  Short periods of zero-G or negative-G operation, caused by a quick dive, turbulence, or even bumping over uneven ground, can jiggle the float and spill liquid fuel into the venturi.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a downdraft or sidedraft carburetor, this liquid falls into the intake manifold and wets the interior walls and may get into the cylinders, causing an over-rich mixture condition.  The engine is said to be &quot;flooded&quot; and will not run until the liquid is cleared out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With an updraft carburetor, the spilled fuel tends to fall out before it can foul anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gravity feed:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your aircraft has fuel tanks higher than the carburetor when in cruise attitude, you may be able to remain under power if your fuel pump fails.  An updraft carburetor can be mounted lower in the engine compartment than sidedraft or downdraft types; in fact, it is usually under the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early automobiles did this to avoid the need for a fuel pump; fuel was fed by gravity from a fuel tank higher than the carburetor, e.g. just below the windshield.  The lower the position of the carburetor, the deeper the fuel tank could be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convenience:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look inside the cowling of most GA planes, you will see much more space under the engine block than above it.  That seems to be the best place for lots of auxiliary equipment and attachments, including the carburetor and air filter.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-01-20T06:02:43.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1175" PostTypeId="2" ParentId="1166" CreationDate="2014-01-20T14:27:49.480" Score="23" Body="&lt;p&gt;I know nothing about this topic but it's quite an interesting one so I did some Googling and found a detailed &lt;a href=&quot;http://chihchin.sg1002.myweb.hinet.net/A330/Carbon%20brakes.pdf&quot;&gt;Airbus document&lt;/a&gt; called &quot;Proper Operation of Carbon Brakes&quot;. It includes the following information:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All brake manufacturers highlight the fact that carbon wear is heavily&#xA;  affected by brake temperature&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is completely different from steel brakes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...energy is theoretically not the primary parameter for carbon wear,&#xA;  whereas it is the  most important one for steel brakes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The document goes on to say this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Generally speaking, to increase carbon brake life, brakes should&#xA;  either be operated cold or hot but not at intermediate warm&#xA;  temperatures&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All recommended braking techniques should aim at reducing the number&#xA;  of brake applications and optimizing the carbon brake temperature&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The specific temperatures mentioned in the document are different for different manufacturers, but generally the intermediate range to avoid seems to be roughly 100-300C. That would explain why 'heavy' braking might be recommended: it's better to use one single brake action that generates more heat and gets into the higher temperatures than to brake multiple times more lightly. Nevertheless, the document also says that overheating is still unsafe and the use of max autobrake is not recommended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a related discussion of exactly this question &lt;a href=&quot;http://www.pprune.org/tech-log/514065-logic-illogic-use-hard-braking-carbon-brakes-long-dry-runways.html#post7830359&quot;&gt;elsewhere&lt;/a&gt; that goes into the physical explanation (although it doesn't quote any sources): at lower temperatures, the carbon becomes a powder which abrades the brake pads, lowering its life; as the temperature rises, the carbon starts behaving like a fluid so the wear is greatly reduced. Most discussions of carbon brakes that I found say that their physical properties and behavior are well documented, but not well understood.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-20T14:27:49.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1176" PostTypeId="1" AcceptedAnswerId="1178" CreationDate="2014-01-20T14:58:45.787" Score="18" ViewCount="7472" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rotax#Aircraft_engines&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rotax engines&lt;/a&gt; have no mixture control, yet they don't seem to have any more problems than other engines at altitude. How do they handle the lower air density in order to not get a too rich a mixture?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="20394" LastEditDate="2021-02-03T16:27:03.810" LastActivityDate="2021-02-03T16:27:03.810" Title="Carbureted Rotax engines have no mixture control, how do they handle less dense air?" Tags="&lt;piston-engine&gt;&lt;mixture&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1178" PostTypeId="2" ParentId="1176" CreationDate="2014-01-20T15:25:49.143" Score="16" Body="&lt;p&gt;According to &lt;a href=&quot;http://legacy.rotax-owner.com/si_tb_info/serviceinfo/5ul89.pdf&quot; rel=&quot;noreferrer&quot;&gt;this owners manual&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;4.5 High altitude compensator (H.A.C. kit)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;H.A.C. is a high altitude compensator developed by ROTAX which adjusts the air/  fuel&#xA;mixture automatically from sea level to 6500 m altitude using a&#xA;special BING  carburetor.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.greenskyadventures.com/bing/hacArticle.htm&quot; rel=&quot;noreferrer&quot;&gt;This page&lt;/a&gt; has information on how the Bing carburetor works (with pictures!):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Here's how it works&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Did you ever wonder what makes fuel flow up the jets, from the&#xA;carburetor float bowl, enroute to the engine? Is it vacuum at the&#xA;venturi?  That's not quite descriptive enough. It is better defined as&#xA;a differential pressure between the float bowl and the venturi. What's&#xA;the pressure in the float bowl? Here is an important hint, the bowl is&#xA;vented to outside atmosphere. So, it should be the same atmosphere, or&#xA;ambient pressure, that's feeding the airfilter.  If it is not,  the&#xA;differential between the venturi and float bowl is going to change and&#xA;so will the mixture...Maybe richer, maybe leaner. Just think of that&#xA;for a second. If  fuel air mixture can be thrown off, accidentally by&#xA;improperly venting the the float bowls, why not control the venting to&#xA;effectively control mixture? That's exactly what your Bing 54 can do,&#xA;automatically, when a High Altitude Compensator is added.  If&#xA;pressure in the float bowl is reduced, relative to the venturi,  less&#xA;fuel makes its way up the jets, and consequently, mixture is leaner.&lt;/p&gt;&#xA;&lt;p&gt;The HAC unit has two chambers separated by a diaphragm. One chamber is&#xA;completely sealed (except during calibration) and air density within&#xA;remains constant. The other has airfilter, float bowl, and venturi&#xA;connections, so air density on this side is variable. It is in this&#xA;chamber, that ambient pressure can be reduced by feeding it to the&#xA;venturi via a connection on late model carburetors. The amount of&#xA;ambient reduction is controlled by a tapered needle which changes&#xA;position with deflection of the diaphragm. Think of the diaphragm as a&#xA;flexible wall between two chambers that allows the sealed side to&#xA;expand or contract as changes in ambient pressure occur on the other&#xA;side. The reduced  (from ambient) pressure gets routed to the float&#xA;bowl(s) via their vent lines with a resulting leaning affect..  If&#xA;that supply of low pressure is shut off, float bowl pressure returns&#xA;to ambient, and the mixture goes as rich as the jets will allow. With&#xA;HAC installations, standard jetting starts out several steps richer.&#xA;This is why we say the default, or failure mode is typically toward&#xA;the rich side.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-20T15:25:49.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1179" PostTypeId="2" ParentId="1176" CreationDate="2014-01-20T15:33:49.287" Score="14" Body="&lt;p&gt;The simple answer to this, is that Rotax employs Constant Depression carburetors, which is a type of &lt;a href=&quot;https://en.wikipedia.org/wiki/Carburetor#Operation&quot; rel=&quot;noreferrer&quot;&gt;Variable-Venturi carburetor&lt;/a&gt;. In essence the fuel/air ratio is adjusted automatically based on air pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuel jet opening is varied by a tapered needles that slides inside the fuel jet and is controlled by a vacuum operated piston.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tE5vS.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="14897" LastEditDate="2017-04-29T09:48:38.253" LastActivityDate="2017-04-29T09:48:38.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1180" PostTypeId="2" ParentId="9" CreationDate="2014-01-20T15:54:56.960" Score="2" Body="&lt;p&gt;Since this question doesn't specify whether the pilot is operating as VFR or IFR or if the pilot has had previous communications with ATC, my best recommendation is to directly exit the airspace and then contact ATC for clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are on an IFR flight plan and following a previous clearance, I would continue on your last assigned clearance and contact ATC as soon as possible. I would not recommend landing inside Class-B airspace without clearance unless you have a communications failure. Even with a failure, it might be more practical/safe to land to the nearest destination outside of Class B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Upon landing, fill out an ASRS report and, depending on the infraction, seek legal advice in some form like &lt;a href=&quot;https://pilot-protection-services.aopa.org/&quot; rel=&quot;nofollow&quot;&gt;AOPA Pilot Protection Services&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-01-20T15:54:56.960" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1181" PostTypeId="1" CreationDate="2014-01-20T16:00:16.720" Score="21" ViewCount="23152" Body="&lt;p&gt;There's a standing tradition, at least in the USA, that a student pilot has their shirt cut, signed and dated by their instructor. What is the origin of this practice and what is its significance?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="7532" LastEditDate="2015-11-01T20:41:00.720" LastActivityDate="2019-09-22T05:00:25.893" Title="Why are student pilots' shirt tails cut after they complete their first solo?" Tags="&lt;flight-training&gt;&lt;student-pilot&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1182" PostTypeId="2" ParentId="1181" CreationDate="2014-01-20T16:08:42.623" Score="28" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/First_solo_flight#Traditions&quot;&gt;Supposedly&lt;/a&gt;, this is because in the early days of flight before intercoms were common instructors used to sit behind their students in a tandem aircraft and pull on their shirt tails to give directions. After successfully soloing, the student has shown that he doesn't need that direction any more and therefore doesn't need his shirt in one piece either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This isn't a universal tradition: I had the end of my tie cut off to mark my first solo (in South Africa). I had to go out and buy a tie first!&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-20T16:08:42.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1183" PostTypeId="1" AcceptedAnswerId="1184" CreationDate="2014-01-20T17:49:23.140" Score="9" ViewCount="6669" Body="&lt;p&gt;Common solutions for aerobatic piston singles is to have either header tanks (for wing tanks, as I understand it) or flop tubes (for fuselage tanks).&lt;br&gt;&#xA;Do fuel systems in a fighter jet work on the same principles? Or are they somehow smarter to allow more erratic maneuvers?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="1467" LastEditDate="2018-04-25T07:58:14.823" LastActivityDate="2018-04-25T07:58:14.823" Title="Do fighter jets have a traditional inverted fuel system?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;&lt;fighter&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1184" PostTypeId="2" ParentId="1183" CreationDate="2014-01-20T18:01:03.720" Score="6" Body="&lt;p&gt;I don't know for certain as I'm not military, but I imagine that they pressurize the fuel tanks using bleed air, much like jet airliners do. It's also likely that they make use of boost and ejector pumps to provide positive pressure directly to more centrally-located tanks which the engines then feed from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Z4XR.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;(from &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_ch14.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AMT Handbook&lt;/a&gt; [pdf])&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15 has both wing &amp;amp; fuselage tanks; &lt;a href=&quot;http://www.f-15e.info/joomla/technology/fuel-system/90-internal-fuel-system&quot; rel=&quot;noreferrer&quot;&gt;according to a site of dubious accuracy (F-15E.info)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The left and right engine feed tanks contain baffles in order to provide a limited amount of fuel to the boost pumps during inverted flight or during negative G maneuvers&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/b7Pvo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Left wing tank&lt;/li&gt;&#xA;  &lt;li&gt;Auxiliary tank&lt;/li&gt;&#xA;  &lt;li&gt;Left engine feed tank&lt;/li&gt;&#xA;  &lt;li&gt;Right wing tank&lt;/li&gt;&#xA;  &lt;li&gt;Right engine feed tank&lt;/li&gt;&#xA;  &lt;li&gt;Tank 1 (main tank)&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://i365.photobucket.com/albums/oo98/shonuff/tank-forum1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Baffles are dividers in the tank itself&lt;/a&gt; that limit the speed at which fuel can flow from one end to another, usually to prevent fuel sloshing and screwing up balance.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-20T18:13:12.380" LastActivityDate="2014-01-20T18:13:12.380" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1185" PostTypeId="2" ParentId="233" CreationDate="2014-01-20T19:21:42.953" Score="5" Body="&lt;p&gt;The stoichiometric mixture is the ideal chemical ratio of air:fuel, that will burn all the fuel in the mixture with no excess oxygen left. It is located at somewhere around 15 parts air and 1 part fuel per unit of mass. Mind you: the ideal ratio is based on mass, not on volume so if air density changes (as you climb/descend), as the carburetor is basically mixing volumes, your air:fuel ratio will change with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mixture control will help you adjust that ideal 15:1 ratio, between what is called &quot;lean&quot; (more than 15 parts air), and &quot;rich&quot; (less than 15 parts).  Most power is available at the ideal ~15:1 so normally that is where you would want to aim your mixture. However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Running a bit on the &quot;rich&quot; side of ideal will consume more fuel,&#xA;generate less power, and might cause carbon deposits, but the&#xA;extra vapor-fuel that remains unburned will serve as a coolant and reduce&#xA;the temperature of your cylinders. That is why most of the times the&#xA;pilots will set mixture on the &quot;rich&quot; side of ideal.&lt;/li&gt;&#xA;&lt;li&gt;Running a bit on the &quot;lean&quot; side of the ideal will consume less fuel,&#xA;will generate a little bit less power, but the lack of cooling from&#xA;the extra fuel will eventually overheat the cylinders, leading to all&#xA;sort of nasty stuff like detonation and overheating the oil. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As for the particular situations calling for operations: 99% of the times you simply want a good/ideal mixture, which is why mixture control is pretty much getting automated&#xA;these days. There are very few exceptions I can think of: for long cruise at cold temperatures I might try a leaner mixture to see if I can skim a couple of pounds of fuel. Or in an emergency engine-coughing situation I might cram the mixture to full rich to prevent the engine from starving or overheating. But then again, if mixture is automated the FADEC will do that anyway.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-20T19:21:42.953" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1186" PostTypeId="5" CreationDate="2014-01-20T21:29:07.833" Score="0" Body="&lt;p&gt;Different types of aircraft &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt; use different types of fuel.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Turboprops and jets burn &lt;a href=&quot;/questions/tagged/jet-fuel&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-fuel&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-fuel&lt;/a&gt;.  The most common jet fuel is &lt;em&gt;Jet A-1&lt;/em&gt;, which is a type of kerosene (in the U.S., &lt;em&gt;Jet A&lt;/em&gt;, which has a slightly higher freezing point but is otherwise very similar to Jet A-1, is used instead); in very cold climates, &lt;em&gt;Jet B&lt;/em&gt;, a 70-30 mixture of gasoline and kerosene, is used, as it has a lower freezing point than Jet A or A-1. Some airlines have tested biofuels as an alternative to traditional hydrocarbons.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Piston-engine aircraft most commonly use &lt;a href=&quot;/questions/tagged/avgas&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;avgas&amp;#39;&quot; rel=&quot;tag&quot;&gt;avgas&lt;/a&gt; - typically &lt;em&gt;100LL&lt;/em&gt;, which is essentially 100 octane leaded gasoline. Because of the relatively high cost of avgas, it's possible to find piston engines that have been built or adapted to use other fuels such as Jet A/A-1, &lt;em&gt;mogas&lt;/em&gt; (motor gasoline, i.e. normal gasoline like that used for road vehicles) or diesel.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;/questions/tagged/fuel-tanks&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel-tanks&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel-tanks&lt;/a&gt; are located differently on different aircraft but they are very commonly placed in the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag is suitable for questions about all fuel types, as well as questions about procedures and regulations related to fuel. Questions about calculating fuel requirements or optimizing fuel use should usually be tagged &lt;a href=&quot;/questions/tagged/performance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;performance&amp;#39;&quot; rel=&quot;tag&quot;&gt;performance&lt;/a&gt; and/or &lt;a href=&quot;/questions/tagged/flight-planning&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-planning&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-planning&lt;/a&gt; as well. Questions about fuel economy should use &lt;a href=&quot;/questions/tagged/fuel-consumption&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel-consumption&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel-consumption&lt;/a&gt; instead.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_fuel&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jet fuel&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Avgas&quot; rel=&quot;nofollow noreferrer&quot;&gt;Avgas&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-09-09T15:54:54.483" LastActivityDate="2019-09-09T15:54:54.483" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1187" PostTypeId="4" CreationDate="2014-01-20T21:29:07.833" Score="0" Body="Different aircraft engines use different fuels; the most common types are Jet A or A-1 for jet and turboprop engines, and avgas for piston engines." OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2018-06-28T18:41:38.430" LastActivityDate="2018-06-28T18:41:38.430" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1188" PostTypeId="2" ParentId="1164" CreationDate="2014-01-20T22:02:25.933" Score="3" Body="&lt;p&gt;I can't speak to techniques for for larger aircraft like the ones you're describing (reverse thrust, etc.), but for light GA aircraft one of the best things you can do to extend the life of your brakes is to not use them for directional or speed control during taxi&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft brake linings are &lt;a href=&quot;http://www.aircraftspruce.com/catalog/pdf/liningconditioningprocess.pdf&quot; rel=&quot;nofollow&quot;&gt;&quot;heat glazed&quot; as part of their initial conditioning&lt;/a&gt;, and the heat from normal use (slowing down after a landing) maintains that glaze, but light brake use wears away the glaze on the surface of the brake linings, which reduces brake effectiveness and increases wear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as landings go, I was always taught to use &quot;aerodynamic braking&quot; as much as possible (keeping the yoke back on the landing rollout). I don't know how much it helps with brake wear, but I find I don't need to be on the brakes as long, and anything that reduces the amount of time the linings and discs are rubbing on each other is probably saving a few millimeters of wear.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sup&gt;1&lt;/sup&gt; – Obviously safety is paramount here - if you're on a downhill taxiway you might &lt;em&gt;have&lt;/em&gt; to ride your brakes unless you can get reverse thrust from your engine(s). Also on planes where differential braking is your sole means of directional control while taxiing just try not to drag the brakes the whole time you're moving.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-03-02T21:41:12.060" LastActivityDate="2015-03-02T21:41:12.060" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1189" PostTypeId="1" AcceptedAnswerId="1190" CreationDate="2014-01-20T22:21:13.480" Score="75" ViewCount="20109" Body="&lt;p&gt;This question is about light, tricycle, single engine aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have made it a habit to raise the flaps right after touchdown (when the nosewheel is on the ground). My instructor used to do that every time during initial training so I took over the habit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes sense to do this for the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;better braking performance because lift is reduced while rolling out&lt;/li&gt;&#xA;&lt;li&gt;less crosswind effect, reducing the risk of loss of directional control after landing&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;(less important) it's part of the after landing checklist, so when it's done, it's done&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, I was recently checked out on a C182 that I wanted to rent in Florida and when I raised the flaps right after touchdown the instructor shouted &quot;&lt;em&gt;what the &amp;lt; beep &gt; are you doing? You should &lt;strong&gt;never&lt;/strong&gt; raise the flaps until you've turned off the runway&lt;/em&gt;&quot;. He couldn't provide a good reason though, so when I told him about the things I listed above he simple mumbled something about keeping my attention on the runway instead of fiddling with the flaps lever (which is a something I don't even have to think about)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: &lt;strong&gt;Is it really a bad idea to raise the flaps that soon after landing? Or is it actually a good habit?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(I noticed that most airliners also wait until they're clear of the runway, but these jets have spoilers to get rid of all the lift)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="19" LastEditDate="2017-03-14T10:08:55.183" LastActivityDate="2021-02-07T20:23:04.023" Title="Is it considered good or bad practice to raise the flaps right after touchdown?" Tags="&lt;landing&gt;&lt;single-engine&gt;&lt;flaps&gt;" AnswerCount="14" CommentCount="14" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1190" PostTypeId="2" ParentId="1189" CreationDate="2014-01-20T22:46:27.573" Score="61" Body="&lt;p&gt;You should wait until clearing the runway before performing &lt;strong&gt;any&lt;/strong&gt; non-essential checklist items because you are still in a critical phase of flight and at a relatively high risk while still on the runway.  You should focus 100% of your attention to controlling the airplane (don't stop flying the airplane until you come to a complete stop) and watching for other traffic (or someone crossing the runway in front of you) that might be a hazard.&lt;/p&gt;&#xA;&lt;p&gt;There is also the possibility that in a retractable gear airplane you could accidently retract the gear if you are moving things while still preoccupied with landing.  Once you exit the runway and come to a complete stop, you can devote the proper attention to the after landing checklist so will be more likely to complete it correctly without missing any items that may become an issue on your next flight.&lt;/p&gt;&#xA;&lt;p&gt;That being said, follow the guidance in your POH.  Sometimes there are abnormal situations that actually call for this, like voretaq7 mentions in his answer, the Cherokee POH references it as a short field landing technique.&lt;/p&gt;&#xA;&lt;h1&gt;FAA Guidance&lt;/h1&gt;&#xA;&lt;p&gt;The FAA also covers this in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2091-73B.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 91-73B - Parts 91 and 135 Single Pilot, Flight&#xA;School Procedures During Taxi Operations&lt;/a&gt;.   It says (in part):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;7. SINGLE-PILOT PROCEDURES.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;a. General.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;In addition, upon  landing, no items should be changed or moved until&#xA;the entire aircraft has crossed the respective  runway’s hold short&#xA;line.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;NOTE: After the entire aircraft crosses over the landing runway’s hold  short line, conduct after-landing checklist items, based upon&#xA;company  procedures, before contacting ATC for taxi instructions.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h1&gt;You could also fail a checkride for doing this&lt;/h1&gt;&#xA;&lt;p&gt;The PTS also repeatedly stresses the  objective:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;strong&gt;Utilizes after landing runway incursion avoidance procedures.&lt;/strong&gt;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;To figure out what they mean by that, we can look at their &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/phak%20-%20appendix%201.pdf&quot; rel=&quot;noreferrer&quot;&gt;Runway Incursion Avoidance&lt;/a&gt; material, which says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Finally, after landing and upon exiting  the runway, ensure your&#xA;aircraft has completely crossed over  the runway hold markings. Once&#xA;all parts of the aircraft have  crossed the runway holding position&#xA;markings, you must hold  unless further instructions have been issued&#xA;by ATC. &lt;strong&gt;Do not  initiate non-essential communications or actions until&#xA;the  aircraft has stopped and the brakes set.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-24T06:54:46.303" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1191" PostTypeId="2" ParentId="1189" CreationDate="2014-01-20T22:46:30.227" Score="35" Body="&lt;p&gt;Raise the flaps after leaving the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A light single doesn't weigh that much and in the short time slowing down from the speed you touchdown at and taxi speed, the difference in weight on wheels between flaps 0 and flaps X is not worth worrying about unless you are landing on a true short field.&lt;/li&gt;&#xA;&lt;li&gt;If the crosswind is that strong, you still need to apply proper control deflection with the flaps up.  Don't let complacency bite you on this one. &lt;/li&gt;&#xA;&lt;li&gt;The after landing checklist is called for after exiting the runway, not while on the runway.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And the biggest reason:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You will fly something bigger and/or complex one day (maybe) and there will be more than a simple flap lever to touch and it is best to wait to mess with those controls until things have settled down and you are taxiing. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That instructor got on your case, I know examiners that will take exception to touching the flaps on the runway and I can say for certain any OE Captain or APD will really get on your case for doing it.  Start proper habits now, particularly if you aspire to fly anything bigger than a light single.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-21T01:11:46.637" LastActivityDate="2014-01-21T01:11:46.637" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1192" PostTypeId="2" ParentId="1189" CreationDate="2014-01-20T22:59:53.830" Score="25" Body="&lt;p&gt;&lt;em&gt;Raising the flaps right after touchdown. Good or Bad?&lt;/em&gt; -- The answer is an emphatic &lt;strong&gt;Yes.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major reason for &lt;strong&gt;&lt;em&gt;not&lt;/em&gt;&lt;/strong&gt; raising your flaps until you've cleared the runway and come to a stop is that it's &lt;em&gt;one more thing&lt;/em&gt; for the pilot to do in an already workload-intensive period (landing). &lt;a href=&quot;https://aviation.stackexchange.com/a/1190/64&quot;&gt;As others have pointed out you might hit the wrong control&lt;/a&gt; or otherwise mess up in a way that can ruin your day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a matter of general procedure I was taught not to raise the flaps until clear of the runway for normal landings, and that's what I do. It seems the safest way to operate since there's always plenty of time to do things after you've cleared the runway and stopped.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The major reason for raising the flaps while you're still on the runway is, as you pointed out in your question, better braking performance - I don't know about for the Cessna 182, but it's mentioned as part of the short field procedures in the Cherokee POH: &lt;code&gt;There will be less chance of skidding the tires if the flaps are retracted before applying the brakes.&lt;/code&gt;&lt;br&gt;&#xA;They're not saying &quot;retract the flaps&quot;, but they're certainly &lt;a href=&quot;http://xkcd.com/552/&quot; rel=&quot;noreferrer&quot;&gt;waggling their eyebrows suggestively while pointing at the flap lever and mouthing &quot;save your tires&quot;&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Empirically (yeah, I tested it, I'm strange like that) retracting the flaps on the Cherokee makes a small but appreciable difference in stopping distance (and a noticeable difference in how hard I can hit the brakes before the tires protest), so when I'm landing on an actual short field or drilling short-field procedures I retract the flaps during rollout at about the same point I would in a touch-and-go landing.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-07-02T22:25:40.867" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1193" PostTypeId="1" AcceptedAnswerId="1194" CreationDate="2014-01-21T00:05:46.653" Score="14" ViewCount="3155" Body="&lt;p&gt;When I extend my flaps to 10 degrees, what exactly is the 10 degrees measuring?  Is this referring to the angle of the flap blades themselves, the new angle of the wing chord, the change in the new critical angle of attack or something else?&lt;/p&gt;&#xA;" OwnerUserId="526" LastEditorUserId="1696" LastEditDate="2015-02-11T22:30:12.377" LastActivityDate="2015-02-11T22:30:12.377" Title="What is the meaning of flap detent names (e.g., 10 degrees)?" Tags="&lt;flight-controls&gt;&lt;flaps&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1194" PostTypeId="2" ParentId="1193" CreationDate="2014-01-21T01:02:26.743" Score="11" Body="&lt;p&gt;The &quot;Degrees&quot; of flap deployment generally refers to the deflection from the neutral (0° - flush with the rest of the wing) position of the flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most GA aircraft this is an actual angular measurement - 10° of flaps corresponds to the flaps lowering 10° from their neutral position, but the degree of travel can also be given as a percentage (0-100%). The aircraft's maintenance manual will specify the actual travel (and specify how it is to be measured), and if specific position detents are provided there will usually be &quot;rigging limits&quot; specified for where each position stop must be &amp;amp; how accurate the control position must be at each stop.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-21T01:02:26.743" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1195" PostTypeId="1" AcceptedAnswerId="1196" CreationDate="2014-01-21T02:01:58.997" Score="8" ViewCount="29944" Body="&lt;p&gt;Under what conditions do I need to have a takeoff alternate airport listed on a dispatch release?  How far away can my takeoff alternate airport be?  Do I need to worry about this in part 91 operations or is it just a 121/135 thing?&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-06-26T10:44:29.923" Title="When do I need a takeoff alternate?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1196" PostTypeId="2" ParentId="1195" CreationDate="2014-01-21T02:24:08.463" Score="7" Body="&lt;p&gt;You should refer to the published IAPs for an airport to determine if it has non-standard takeoff minimums (for AeroNav charts, this is the T in the black triangle). There's a section on this in the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;noreferrer&quot;&gt;Instrument Procedures Handbook, Chapter 2&lt;/a&gt; (2-6):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The FAA establishes takeoff minimums for every airport that has published Standard Instrument Approaches. These minimums are used by commercially operated aircraft, namely Part 121 and 135 operators.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=95dae076de30f143ad7226ea63cb8a26&amp;amp;node=14:3.0.1.1.11.4.3.9&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.217 describes the requirements for the alternate airport&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No person may takeoff an aircraft under IFR from an airport where weather conditions are at or above takeoff minimums but are below authorized IFR landing minimums unless there is an alternate airport within 1 hour's flying time (at normal cruising speed, in still air) of the airport of departure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;...and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=88e39598f91a7b96021dc5c72904ac7b&amp;amp;node=14:3.0.1.1.7.21.3.14&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;so does 14 CFR 121.617&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(1) Aircraft having two engines. Not more than one hour from the departure airport at normal cruising speed in still air with one engine inoperative.&lt;/p&gt;&#xA;&lt;p&gt;(2) Aircraft having three or more engines. Not more than two hours from the departure airport at normal cruising speed in still air with one engine inoperative.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;Part 91&lt;/h2&gt;&#xA;&lt;p&gt;14 CFR 91 does not require a takeoff alternate. I'm going to quote the IFH again because it's an authoritative FAA source and because I very much agree with it (2-6):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Aircraft operating under Part 91 are not required to comply with established takeoff minimums. Legally, a zero/zero departure may be made, but it is never advisable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-21T02:37:11.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1197" PostTypeId="1" CreationDate="2014-01-21T03:32:19.373" Score="8" ViewCount="4421" Body="&lt;p&gt;There are various services that use world-wide Boeing Winds for forecast wind data which can be used to calculate an approximate flight time between two locations.  They usually have best case, worst case, and average case for each location, altitude, and date in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have searched and searched Google to no avail.  Where can this wind data be found, and how can it be used in a commercial product?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those of you who don't know what the Boeing winds are, I found this description of their software product on am informal message board (not related to Boeing):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;PC WindTemp&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;INTRODUCTION&lt;/strong&gt; &lt;br&gt;&#xA;  The Boeing PC Windtemp program provides global average and statistical winds and temperatures aloft over a 30 year&#xA;  period. These data are used primarily for comparative transport&#xA;  airplane performance and economic studies. The data may also be used&#xA;  for transport airplane route planning on an annual, seasonal, or&#xA;  monthly basis.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note: Actual winds and temperatures at a specific location and time&#xA;  may differ appreciably from those computed by PC Windtemp. Therefore,&#xA;  data from PC Windtemp must not be used for flight planning, aircraft&#xA;  dispatch, airborne flight navigation, or any other type of actual&#xA;  flight operations.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;PROGRAM FEATURES&lt;/strong&gt; &lt;br&gt;&#xA;  A seasonal and monthly database with global coverage from 1000 millibars (364 feet pressure altitude) to 10&#xA;  millibars (101,885 feet pressure altitude). Annual data updates to the&#xA;  most recent 30 year period. Airport codes and coordinates may be&#xA;  imported from a text file in a comma separated value (CSV)&#xA;  format Calculates enroute wind and temperature for up to 50 airport&#xA;  pairs at a time. Calculates enroute wind and temperature for simple&#xA;  great circle tracks or tracks with up to 250 waypoints, with or&#xA;  without altitude changes. Calculates average enroute wind and&#xA;  temperature or any reliability (quantile) between 50% and 99%. Months&#xA;  or seasons, reliabilities, altitudes, and speeds may be nested for&#xA;  input efficiency. Formatted and text output reports are&#xA;  available. Program subroutines (DLLs) can be called from other&#xA;  programs written with C++ or Visual Basic in order to incorporate&#xA;  Windtemp functionality in those programs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="504" LastEditDate="2014-01-21T16:52:34.270" LastActivityDate="2014-01-21T16:52:34.270" Title="Where can Boeing wind data be found?" Tags="&lt;wind&gt;&lt;boeing&gt;&lt;winds-aloft&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1198" PostTypeId="2" ParentId="1189" CreationDate="2014-01-21T03:59:40.057" Score="11" Body="&lt;p&gt;I say bad for some planes. Also other planes it will be bad in some conditions.  So follow what the operations manual says for that plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using full flaps is a very high drag and very poor L/D ratio configuration for the plane to be in. By raising flaps the potential increase in tire grip (from reduced lift) for braking is offset partially or entirely by the reduction in aerodynamic drag.  There will be a speed threshold somewhere that will mean fully retracted flaps provides more braking than full flaps, but don't forget you have to transition from fully extended to retracted giving you a surge in your L/D ratio. Remember that takeoff flaps setting gives better L/D ratio than no flaps at that speed and AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of those things changing during landing does not lend itself to smooth, predictable, and easier controlled deceleration.  Plus, as others have pointed out, retracting your flaps partway through a landing distracts you from your task at hand, and for limited or no benefit or even, worse braking performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:  The better braking performance with flaps up may be true for some planes but not for all &quot;light&quot; tricycle single engine aircraft.  This will depend on many design factors that the operation manual authors choose to use the &lt;a href=&quot;http://en.wikipedia.org/wiki/Keep_it_simple&quot; rel=&quot;noreferrer&quot;&gt;KISS principal&lt;/a&gt; and just say always continue the rollout with the full flaps until you're off the runway or parked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During rollout the wings may transition from flying to fully stalled due to the reduced air speed while on full flaps.  This will be a sever reduction in lift, that greatly enhances tire grip, while at the same time has all of the drag as before.  If the flaps are retracted in this sort of plane at that stage the wings may go back to flying while at the same time reducing the amount of drag (giving the surge in L/D).  This surge will be particularly bad during the transition from full to no flaps.  Even though there will not be enough lift to make any wheels come up, it will reduce the tire grip.  That reduction in grip could cause one of the rear wheels to skid, suddenly reducing the braking performance of one side of the aircraft and cause the plane to spin around.  Depending on the speed you're going when your nose gear touches down and you decide to retract the flaps, this could be very bad.  Even if that extreme doesn't happen, the the loss of tire grip at the same time as a reduction in drag from the flaps means less braking performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the planes the OP flies their wings may remain flying (not stalled) for the &quot;high&quot; speed part of the rollout that aerodynamic forces are significant, so retracting the flaps severely reduces the lift and a bit of drag, giving the tires much more grip and braking power than any loss of aerodynamic braking provided by the flaps.&lt;/p&gt;&#xA;" OwnerUserId="656" LastEditorUserId="-1" LastEditDate="2014-01-28T17:32:03.513" LastActivityDate="2014-01-28T17:32:03.513" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1199" PostTypeId="1" AcceptedAnswerId="1380" CreationDate="2014-01-21T05:08:20.997" Score="8" ViewCount="29188" Body="&lt;p&gt;In the US, what are the requirements that a student pilot must demonstrate to their examiner  before they can take a checkride for their private pilot airplane certificate?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-28T03:09:10.583" LastActivityDate="2016-09-19T04:47:22.260" Title="What are the requirements to take the private pilot check ride?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;logging&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1200" PostTypeId="2" ParentId="1197" CreationDate="2014-01-21T06:19:10.420" Score="1" Body="&lt;p&gt;The wind data that Jeppesen/Boeing uses is proprietary, they have their own meteorologists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar data is available from &lt;a href=&quot;http://aviationweather.gov/&quot; rel=&quot;nofollow&quot; title=&quot;Aviationweather.gov&quot;&gt;NOAA&lt;/a&gt;.  They have a data server that can provide wind information.&lt;/p&gt;&#xA;" OwnerUserId="534" LastActivityDate="2014-01-21T06:19:10.420" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1201" PostTypeId="2" ParentId="258" CreationDate="2014-01-21T08:40:36.847" Score="6" Body="&lt;p&gt;The factors and solutions are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;pilot: there are a few options&#xA;&lt;ul&gt;&#xA;&lt;li&gt;make it an unmanned aerial vehicle (UAV).&lt;/li&gt;&#xA;&lt;li&gt;and/or make it so it can be intercepted mid flight for crew and supply changes.&lt;/li&gt;&#xA;&lt;li&gt;and/or make it self sufficient. This would require a massive aircraft if it is even possible, certainly not at the moment (2014), though partial self sufficiency could be doable with today's technology.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;fuel: make it solar. Solar aircraft can store energy as altitude and/or batteries to remain aloft at night.  A Solar panel's life is typically considered about 50 years at which time they produce 50% of their original power.  There have been a few examples like the &lt;a href=&quot;http://en.wikipedia.org/wiki/NASA_Helios&quot; rel=&quot;nofollow&quot;&gt;NASA Helios&lt;/a&gt; that could stay aloft 24/7.&lt;/li&gt;&#xA;&lt;li&gt;bad weather avoidance: has to be fast enough to get out of the way&lt;/li&gt;&#xA;&lt;li&gt;consumables: like oil/grease, etc&#xA;&lt;ul&gt;&#xA;&lt;li&gt;use non-contact bearings where you can to reduce the need. You can't replace all of them due to the inherent instabilities of non-contact bearings.  It is particularly problematic with bearings around high power/load shafts such as thrust bearings responsible for preventing the prop shaft from pulling out of the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;you could also provide systems for replenishing these consumables.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;moving parts wear:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;limit the number of moving parts. Electric motors can be built with only 1 moving part&lt;/li&gt;&#xA;&lt;li&gt;provide systems to bring replacements on board and install them with either maintenance droids (yes like the function that R2D2 was supposed to be for), or with maintenance crew that will also need a way on and off the plane.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;material fatigue such as parts that are developing fatigue fractures and also materials that suffer weather damage (eg plastics/paint degrading due to UV light or metal corrosion): this one is tough as I can't think of anything to replace a critical structural component such as a wing spar in flight.  Repairs may be able to be made by temporarily providing alternate structural integrity (think of something like scaffolding but providing structural support around the affected area) while in-situ material repairs are made in the area with damage.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Maintenance is the biggest issue. &lt;a href=&quot;http://titanaerospace.com/august-29-2013-huge-solar-plane-could-fly-for-five-years&quot; rel=&quot;nofollow&quot;&gt;Titan Aerospace&lt;/a&gt; offers UAV aircraft that can stay aloft for 5 years at a time.  Basically it can stay in flight until it breaks like the &lt;a href=&quot;http://en.wikipedia.org/wiki/NASA_Helios&quot; rel=&quot;nofollow&quot;&gt;NASA Helios&lt;/a&gt; did.  Essentially the current thinking is to make it relatively cheap and unmanned while we figure out the average life expectancy of these things so we can bring them in for repair/decommissioning.&lt;/p&gt;&#xA;" OwnerUserId="656" LastEditorUserId="656" LastEditDate="2014-03-28T10:14:48.940" LastActivityDate="2014-03-28T10:14:48.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1202" PostTypeId="1" AcceptedAnswerId="1205" CreationDate="2014-01-21T09:48:57.660" Score="4" ViewCount="2224" Body="&lt;p&gt;I was reading a POH which stated something along the lines of&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;NOTE&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Except as noted, all airspeeds quoted in this handbook are Indicated&#xA;  Airspeeds (IAS) in Knots and assume zero instrument error.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why didn't they denote that as CAS (calibrated airspeed) instead, which is without instrument error? Is there a key difference between the two that I'm missing?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-21T10:43:03.687" LastActivityDate="2014-01-22T07:43:25.637" Title="Is IAS without instrument error the same as CAS?" Tags="&lt;flight-instruments&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1203" PostTypeId="2" ParentId="1202" CreationDate="2014-01-21T09:56:52.227" Score="3" Body="&lt;p&gt;Instrument error is usually something to do with the actual instrument (like the arm on the dial or something). The primary difference between IAS and CAS as I understand it is air pressure discrepancies in the Pitot-tube due to different angle of attacks and airflow disturbances due to the airframe. The POH of the Katana DA20 I regularly fly has a chart mapping IAS/CAS, with two different lines corresponding to different flaps configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm no aeronautical engineer and this is a layman's understanding, so feel free to correct me. As I understand it, IAS (without instrument error) is the measured air pressure, CAS is the theoretical air pressure which would've have been measured, would it be possible to measure it perfectly, and instrument error is due to machining imprecisions or otherwise errors in the construction of the instrument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently the question wasn't if IAS without instrument error is the same as CAS, but why not use CAS throughout the POH. The easy answer is, since the CAS cannot be measured, but IAS can (to the extent that construction precision allow) and is displayed to the pilot, why should he memorize numbers which he'll never see? Charting IAS makes much more sense, and although they'll be offset by instrument errors, those are (generally) individual to the aircraft, and so it's the closest you're going to get in a printed manual which is not a one-of copy for a single aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/CzDVzyk.png&quot; alt=&quot;POH Chart IAS/CAS&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-01-21T10:26:15.563" LastActivityDate="2014-01-21T10:26:15.563" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1204" PostTypeId="2" ParentId="1166" CreationDate="2014-01-21T10:04:06.793" Score="18" Body="&lt;p&gt;The amount of time spent on the brakes is the most important thing which dictates the wear of carbon brakes, not the amount of energy put into them (which is the case with steel brakes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By braking harder, &lt;strong&gt;you are spending less time on the brakes&lt;/strong&gt; in total, which means that you will have less wear on the brakes. Let's just imaging you wear 1/10000th of the brake every second, no matter how hard or soft you brake. By braking lightly, taking 20 seconds to stop, you'd wear out 1/500th of the brake. But if you only took 10 seconds, you'd wear just 1/1000th of the brake. While it's not &lt;em&gt;quite&lt;/em&gt; as simple as that, that's the general idea of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another contribution factor is the non-linear and non-proportional correlation between brake wear and brake temperatures. While this is slightly counter-intuitive, brake wear increases until about 200°C disk temperature (note that indicated temperature is usually lower), then it actually &lt;em&gt;decreases&lt;/em&gt; from there until it becomes much hotter (about 700-800°C). So, by braking harder, you will also heat up the brakes to the point where brake wear is &lt;em&gt;less&lt;/em&gt; than by braking lightly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of this, it's better to apply the brakes in one go, to reduce the total time on the brakes. Boeing's excellent article on the &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_03_09/article_05_1.html&quot; rel=&quot;noreferrer&quot;&gt;Operational Advantages of Carbon Brakes&lt;/a&gt; gives the following advice when taxiing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;Taxi braking recommendations for carbon and steel brakes&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;Because the wear mechanisms are different between carbon and steel&#xA;  brakes, different taxi braking techniques are recommended for carbon&#xA;  brakes in order to maximize brake life.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Steel brake wear is directly proportional to the kinetic energy&#xA;  absorbed by the brakes. Maximum steel brake life can be achieved&#xA;  during taxi by using a large number of small, light brake&#xA;  applications, allowing some time for brake cooling between&#xA;  applications. High airplane gross weights and high brake application&#xA;  speeds tend to reduce steel brake life because they require the brakes&#xA;  to absorb a large amount of kinetic energy.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Carbon brake wear is primarily dependent on the total number of brake&#xA;  applications — one firm brake application causes less wear than&#xA;  several light applications. Maximum carbon brake life can be achieved&#xA;  during taxi by using a small number of long, moderately firm brake&#xA;  applications instead of numerous light brake applications. This can be&#xA;  achieved by allowing taxi speed to increase from below target speed to&#xA;  above target speed, then using a single firm brake application to&#xA;  reduce speed below the target and repeating if required, rather than&#xA;  maintaining a constant taxi speed using numerous brake applications.&#xA;  Carbon brake wear is much less sensitive to airplane weight and speed&#xA;  than steel brake wear.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;These recommendations are intended as general taxi guidelines only.&#xA;  Safety and passenger comfort should remain the primary considerations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2015-06-11T06:40:24.550" LastActivityDate="2015-06-11T06:40:24.550" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1205" PostTypeId="2" ParentId="1202" CreationDate="2014-01-21T10:28:10.043" Score="5" Body="&lt;p&gt;Even without instrument error, IAS does not equal CAS. This because there are two kinds of errors that make up the difference between Indicated Airspeed (IAS) and Calibrated Airspeed (CAS)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Installation error&lt;/li&gt;&#xA;&lt;li&gt;Instrument error&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Installation error&lt;/strong&gt; is basically a pressure error. Airspeed measurement is a measure of dynamic pressure of the undisturbed airflow. When the pitot tube is not placed directly into undisturbed airflow the IAS will not equal the CAS. Another source of installation error are leaks in the pitot system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Instrument error&lt;/strong&gt; is the error introduced by ASI itself by transforming the pressure to a speed indication. For example calibration errors of the pressure sensor or excessive friction in the mechanical drive system of the dial fall into this category. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The POH in your example assumes no Instrument error, but is corrected for installation error. An implicit assumption is made that there are no leaks in the system, so the POH corrects for airflow disturbances. That is why some aircraft have different tables for different configurations; the configurations affect the airflow around the pitot tube.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft equipped with electronic Air Data Computers (ADC's) the installation error is sometimes automatically corrected by making use of angle of attack sensors, electronic configuration information and lookup tables.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-01-22T07:43:25.637" LastActivityDate="2014-01-22T07:43:25.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1206" PostTypeId="2" ParentId="1197" CreationDate="2014-01-21T10:40:53.037" Score="0" Body="&lt;p&gt;Usually inside the dispatch document, you will have a list with all enroute fixes, like this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;FIX    FREQ     AWY   WIND    COORDS&#xA;---------------------------------------  &#xA;VKZ    123.45   UN857 235/60º W... S... &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Usually airlines have their own system to deal with that, but search about lufthansa's LIDO, they can provide this information for you, click &lt;a href=&quot;https://www.lhsystems.com/solutions-services/airline-solutions-services/flight-deck-solutions/lidoflightplanning/lidoflight/lidoflight-modules/lidoflight-winds.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; to understand a little bit more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as said by Jim, all data is provided by NOAA via winds aloft charts, you can find it &lt;a href=&quot;http://www.aviationweather.gov/sitemap/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, section &quot;Wind and Temperature&quot;.  &lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="74" LastEditDate="2014-01-21T13:00:39.670" LastActivityDate="2014-01-21T13:00:39.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1207" PostTypeId="2" ParentId="1199" CreationDate="2014-01-21T11:40:30.323" Score="4" Body="&lt;p&gt;I'm sure someone will post the exact regs, but as a stop-gap, from memory:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;40 hours (35 if the school is part 141) minimum total time&lt;/li&gt;&#xA;&lt;li&gt;20 hours dual instruction&lt;/li&gt;&#xA;&lt;li&gt;3 hours flight &quot;by reference to instruments&quot; (under the hood)&lt;/li&gt;&#xA;&lt;li&gt;5 hours solo cross country (50nm minimum between two points along each trip)&lt;/li&gt;&#xA;&lt;li&gt;One solo 150nm XC flight with at least 3 airports (two of which must be at least 50nm apart)&lt;/li&gt;&#xA;&lt;li&gt;3 hours night flight (dual instruction)&lt;/li&gt;&#xA;&lt;li&gt;One night XC (dual)&lt;/li&gt;&#xA;&lt;li&gt;10 night landings (full stop)&lt;/li&gt;&#xA;&lt;li&gt;3 hours of dual instruction explicitly for check ride prep, within 90 days of the check ride&lt;/li&gt;&#xA;&lt;li&gt;Endorsements for the items above needing endorsements&lt;/li&gt;&#xA;&lt;li&gt;An endorsement from a CFI stating the candidate is prepared for the check ride.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Additionally, mine has a statement that my (part 61) CFI had seen my US passport (and its number) establishing proof that I am a US citizen, in accordance with 49 CFR 1552.3(A).&lt;/p&gt;&#xA;" OwnerUserId="73" LastEditorUserId="73" LastEditDate="2014-01-22T12:16:41.933" LastActivityDate="2014-01-22T12:16:41.933" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1208" PostTypeId="2" ParentId="1189" CreationDate="2014-01-21T12:49:45.277" Score="4" Body="&lt;p&gt;I guess it depends on the situation. If you do raise them make sure that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You won't be going-around&lt;/li&gt;&#xA;&lt;li&gt;You don't move another control by mistake&lt;/li&gt;&#xA;&lt;li&gt;The aircraft is stable&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Thanks to all those who answered. Lots of interesting and useful information here.&lt;/p&gt;&#xA;" OwnerUserId="665" LastEditorUserId="665" LastEditDate="2020-03-19T16:07:06.957" LastActivityDate="2020-03-19T16:07:06.957" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1209" PostTypeId="2" ParentId="1197" CreationDate="2014-01-21T15:02:27.270" Score="3" Body="&lt;p&gt;An alternative to the Boeing data (if it exists, you might need to call one of their sales reps to find it) is publicly available meteorological data.  One such project is the &lt;a href=&quot;http://www.esrl.noaa.gov/psd/data/reanalysis/reanalysis.shtml&quot; rel=&quot;nofollow&quot;&gt;NCEP/NCAR Reanalysis Project&lt;/a&gt;.  There are a few others, as well as archived data.  None of these is exactly the Boeing dataset, but I'd bet that the Boeing dataset is based at least in part upon data like these.  The benefit to the data below is that in most cases it is free and there is a lot of it.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Reanalysis Data&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Reanalysis data is constructed from the best available past observations, which are assimilated into a weather model to fill in the gaps between obs and in time.  There are many such projects with various scales (global, regional) and time periods.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;The &lt;a href=&quot;http://www.esrl.noaa.gov/psd/data/reanalysis/reanalysis.shtml&quot; rel=&quot;nofollow&quot;&gt;NCEP/NCAR Reanalysis Project&lt;/a&gt;&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This dataset has 4-times-daily, daily and monthly values between 1948 and present and long term monthly means for 1981-2010.  The data is global. The data is publicly available and you can retrieve files in &lt;a href=&quot;http://www.unidata.ucar.edu/software/netcdf/&quot; rel=&quot;nofollow&quot;&gt;NetCDF&lt;/a&gt; format from the linked website.  The wind data is stored on pressure levels (e.g. 1000 mb, 500 mb, 250 mb) and is stored in its u (east-west) and v (north-south) components separately.  &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;The &lt;a href=&quot;http://www.ecmwf.int/products/data/archive/descriptions/e4/index.html&quot; rel=&quot;nofollow&quot;&gt;ERA40&lt;/a&gt;&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This dataset is a global dataset covering 1957-2002 and has various output resolutions available.  Output from ECMWF is typically in the GRIB format and not all of it is free for non-research use.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;The &lt;a href=&quot;http://www.emc.ncep.noaa.gov/mmb/rreanl/&quot; rel=&quot;nofollow&quot;&gt;NARR&lt;/a&gt;&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The North American Regional Reanalysis, as the name suggests, is a regional dataset covering North America.  The data covers 1979 - present.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Observations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Long term past observations are archived at the &lt;a href=&quot;http://www.ncdc.noaa.gov/data-access&quot; rel=&quot;nofollow&quot;&gt;NCDC&lt;/a&gt; and include surface stations, weather balloons and model data, among others.  From the various models available a statistical representation of winds could feasibly be produced.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-21T15:02:27.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1210" PostTypeId="1" CreationDate="2014-01-21T16:18:28.787" Score="18" ViewCount="160659" Body="&lt;p&gt;There seems to be many regulation bodies across the globe, how are they different and how are they alike? Specifically, how is ICAO different from the rest?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="72" LastEditDate="2014-01-23T03:43:20.857" LastActivityDate="2016-07-09T12:09:02.870" Title="What is the difference between ICAO, JAA, FAA, EASA, and CAA?" Tags="&lt;faa&gt;&lt;icao&gt;&lt;easa&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1212" PostTypeId="2" ParentId="1199" CreationDate="2014-01-21T17:01:40.673" Score="2" Body="&lt;p&gt;Mah explained everything very well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The non-flying requirements are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Be at least 17 years old (14 years old for glider or balloon rating)&lt;/li&gt;&#xA;&lt;li&gt;Be able to read, speak, write and understand the English language&lt;/li&gt;&#xA;&lt;li&gt;Obtain at least a third class medical certificate from an Aviation Medical Examiner &lt;/li&gt;&#xA;&lt;li&gt;Pass a paper/computerized aeronautical knowledge test&lt;/li&gt;&#xA;&lt;li&gt;Pass an oral test and flight test administered by an FAA inspector, FAA-designated examiner, or authorized check instructor&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States#Private_pilot&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="17036" LastEditDate="2016-09-19T04:47:22.260" LastActivityDate="2016-09-19T04:47:22.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1213" PostTypeId="2" ParentId="1189" CreationDate="2014-01-21T17:11:14.393" Score="6" Body="&lt;p&gt;You say that you don't even think about 'flipping the lever'.&#xA;Well, that means that you missed something very basic in flying habits.&#xA;Raising the flaps means - moving that relevant lever AND making sure that they are up - either visually or by indicator. This you should not be doing while taxiing and definitely not ON the runway.&#xA;Just like when you take of you apply full power - which means - you push the throttle all the way in AND check you have max RPM and all you engine gauges are green.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My answer is a definite - No.&lt;/p&gt;&#xA;" OwnerUserId="671" LastActivityDate="2014-01-21T17:11:14.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1214" PostTypeId="1" AcceptedAnswerId="1221" CreationDate="2014-01-21T18:06:54.423" Score="4" ViewCount="111" Body="&lt;p&gt;Are there any online records that may indicate why a specific DPE may have lost qualifications recently?&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="1696" LastEditDate="2015-02-11T22:12:47.123" LastActivityDate="2015-02-11T22:12:47.123" Title="Are records of certificate actions available?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1215" PostTypeId="2" ParentId="1214" CreationDate="2014-01-21T18:21:26.983" Score="1" Body="&lt;p&gt;It probably won't answer your questions directly, but you can begin by looking through the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/operations/agc300/reports/Quarters/&quot; rel=&quot;nofollow&quot;&gt;FAA's Quarterly Enforcement Reports&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(You may be able to find more detailed information somewhere else on that same site. I'm not sure.)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-21T18:21:26.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1216" PostTypeId="1" AcceptedAnswerId="1217" CreationDate="2014-01-21T18:27:46.600" Score="9" ViewCount="1155" Body="&lt;p&gt;For normal sightseeing flights in a typical hot air balloon, what instruments or avionics does the pilot usually carry? Do balloons have a minimum equipment list?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="1467" LastEditDate="2016-05-25T10:37:17.053" LastActivityDate="2016-05-25T10:37:17.053" Title="What instruments or avionics do balloons usually have?" Tags="&lt;flight-instruments&gt;&lt;lighter-than-air&gt;&lt;balloon&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1217" PostTypeId="2" ParentId="1216" CreationDate="2014-01-21T19:08:54.843" Score="5" Body="&lt;p&gt;The magic regulation for minimum equipment on a balloon (in the USA) is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.15&amp;amp;idno=14#14:1.0.1.3.15.6.363.4&quot; rel=&quot;noreferrer&quot;&gt;14CFR31.85 (&quot;Required Basic Equipment&quot; for manned free-air balloons)&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requires that balloons be equipped with:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;For all balloons&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;[Reserved]&lt;/li&gt;&#xA;  &lt;li&gt;An altimeter.&lt;/li&gt;&#xA;  &lt;li&gt;A rate of climb indicator.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h3&gt;For hot air balloons (additional equipment):&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;A fuel quantity gauge.  &lt;/li&gt;&#xA;  &lt;li&gt;An envelope temperature indicator.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h3&gt;For captive gas balloons (additional equipment):&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A compass.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Beyond what's required by regulation, in most free balloon operations I've seen they also carry an aviation radio and/or a CB radio (to communicate with their ground crew) - this is usually a handheld transceiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/faa-h-8083-11.pdf&quot; rel=&quot;noreferrer&quot;&gt;The FAA Balloon Flying Handbook&lt;/a&gt; also makes for interesting reading. They talk about required and optional instruments and equipment found on various types of balloons in Chapter 2.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-21T19:08:54.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1218" PostTypeId="1" AcceptedAnswerId="1249" CreationDate="2014-01-21T20:26:47.110" Score="17" ViewCount="950" Body="&lt;p&gt;I know some uncontrolled airports can have more operations per day than many controlled airports. That got me wondering what the process is for the change to a towered, controlled airport. I know a control tower was recently built (2005) at Provo, UT (KPVU) which is the second busiest airport in Utah. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there simply a threshold of average operations/day? Do the number of accidents and incidents come into play?&lt;/li&gt;&#xA;&lt;li&gt;Does the FAA start the process or does the community have to lobby for the tower?&lt;/li&gt;&#xA;&lt;li&gt;Who pays for the tower, is it all federal FAA funds or does the state and city where the airport is located pay?&lt;/li&gt;&#xA;&lt;li&gt;Are there any US airports where towers are being built or considered? Given the recent sequestration and how close we came to having over 100 towers shut down, I'm guessing any current plans are on hold.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="81" LastEditorUserId="62" LastEditDate="2014-01-21T21:09:25.977" LastActivityDate="2014-01-22T23:05:56.313" Title="What's the process for an uncontrolled airfield to become controlled/towered?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1219" PostTypeId="1" AcceptedAnswerId="1220" CreationDate="2014-01-21T20:39:49.543" Score="30" ViewCount="15284" Body="&lt;p&gt;I understand that a large(r) commercial jet slows down after landing using the following methods:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wheel brakes&lt;/li&gt;&#xA;&lt;li&gt;Reverse thrust&lt;/li&gt;&#xA;&lt;li&gt;Spoilers/flaps/airbrakes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What is the effectiveness of each compared to the others? What if one of the first 2 fails? Can an airliner usually be stopped without using wheel brakes or without using reverse thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what if the runway is slick because of rain, snow or ice? Does that change the equation?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-21T20:57:48.727" LastActivityDate="2019-07-16T10:04:26.073" Title="For large jets, what is the primary means of slowing down after landing?" Tags="&lt;landing&gt;&lt;airliner&gt;&lt;braking&gt;&lt;thrust-reverser&gt;" AnswerCount="6" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1220" PostTypeId="2" ParentId="1219" CreationDate="2014-01-21T20:46:59.017" Score="29" Body="&lt;p&gt;The brakes are much more effective than anything else, at least for the jet I have experience in (EMB-145).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our landing performance data typically assumes full braking application, spoilers deployed and no reverse thrust.  The airplane will most certainly stop without using reverse thrust, just not as fast.  I never tried not using the brakes, and if I were to I would want a light airplane and a very long runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Lnafziger pointed out in the comments, the brakes are part of redundant systems so that they are always available.  In the EMB-145, the brakes were serviced by two independent* hydraulic systems. The inboard brakes were on one system while the outboards were on the other for a total of four wheels each with big carbon fiber brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To address the comments on slick runways, assuming braking action allows an attempt to land in the first place, you have to be careful. With reverse thrust alone you may not be able to maintain the runway centerline and directional control may become difficult through uneven deployment of the reversers and other factors.  In this scenario the spoilers are helpful to increase traction and brake effectiveness.  In short, if the runway is slick then the only way I'm attempting a no-wheel-brake landing is after declaring an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, to address the question in the title, the wheel brakes are always the primary means of slowing the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*&lt;sub&gt;You could transfer fluid between our systems through the parking brake.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="16724" LastEditDate="2019-07-16T10:04:26.073" LastActivityDate="2019-07-16T10:04:26.073" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1221" PostTypeId="2" ParentId="1214" CreationDate="2014-01-21T20:48:30.410" Score="2" Body="&lt;p&gt;Due to privacy concerns, certificate actions are not made publicly available without a formal request, and have to be made via an acceptable means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a document titled &lt;a href=&quot;http://www.faa.gov/pilots/lic_cert/pria/guidance/&quot; rel=&quot;nofollow&quot;&gt;Information Provided by PRIA, FOIA, and the Privacy Act&lt;/a&gt; which goes into details about how information can be requested and what they will provide:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;PRIA is basically a request made by a hiring air carrier, so you wouldn't be able to do that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;FOIA is the Freedom of Information Act, and the above document states:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Through FOIA, ANY enforcement action, whether still open or fully&#xA;  adjudicated and closed, can be reported.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Privacy Act allows you to request your own records, or a third party &lt;em&gt;company&lt;/em&gt; may request records, so neither of these would apply in your case either.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-21T20:48:30.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1222" PostTypeId="2" ParentId="1219" CreationDate="2014-01-21T21:13:23.667" Score="14" Body="&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=wXpjBxD0Rhg&quot;&gt;This video&lt;/a&gt; on YouTube shows a 777 in certification trials, accelerating at maximum gross weight from standing start to $V_R$, then stopping with maximum brake pressure and no reverse thrust. The brake discs are also ground down to the minimum thickness permitted by the maintenance manual to simulate the worst case scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The brakes get white hot!  Then the plane has to taxi for 5 minutes, before having the fire department cool the brakes.  The test is to ensure that the brakes can handle the maximum load as certified, and secondly that the brakes do not catch on fire and incinerate the airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the runway is slick it just takes longer to stop.  Thrust reverse will help significantly in this case.  Thrust reverse is prohibited below a certain speed because the reverse thrust will kick up FOD which the engines may suck in, causing expen$ive damage.  However, in an emergency, thrust reverse will stop the plane.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="97" LastEditDate="2014-04-16T23:37:52.080" LastActivityDate="2014-04-16T23:37:52.080" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1223" PostTypeId="1" AcceptedAnswerId="1236" CreationDate="2014-01-21T22:45:02.137" Score="11" ViewCount="10004" Body="&lt;p&gt;I suspect most pilots have done it at least once: briefly experience zero g when flying a parabolic path. It's quite an experience (if your stomach can handle it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question is: are there any risks involved in doing something like that? (I know, getting in an airplane by itself is a risk, but that's not the point)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could think of a few potential risks, but I'm not sure if they are real or not:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine lubrication in single engine piston airplanes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And if not properly executed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Risk of a stall, both in the pull up phase and in the &quot;arc&quot; phase&lt;/li&gt;&#xA;&lt;li&gt;Overstressing the airplane when pulling out of the dive to get up to speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Follow-up questions: Is it considered to be an acrobatic maneuver? Are there any regulations that would prohibit it?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="69" LastEditDate="2014-01-21T22:52:22.790" LastActivityDate="2014-01-22T16:48:30.723" Title="What are the risks involved when doing a classic zero-g maneuver?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1224" PostTypeId="1" CreationDate="2014-01-21T23:00:11.480" Score="3" ViewCount="268" Body="&lt;p&gt;If an airplane is already equipped for RVSM flight, how do we obtain a Letter of Authorization (LOA) for RVSM in order to actually fly in RVSM airspace?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-22T15:51:22.210" Title="How is RVSM approval obtained for a properly equipped airplane?" Tags="&lt;faa&gt;&lt;far-91&gt;&lt;rvsm&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1225" PostTypeId="2" ParentId="263" CreationDate="2014-01-21T23:41:58.110" Score="6" Body="&lt;p&gt;When a US registered pilot is operating in international airspace, he is bound by both the US aviation regulations (14 CFR) and ICAO Annex 2, as required by 14 CFR 91.703.  It also requires compliance with MNPS and RVSM airspace rules where appropriate.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Sec. 91.703 - Operations of civil aircraft of U.S. registry outside of the United States.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Each person operating a civil aircraft of U.S. registry outside of&#xA;  the United States shall--&lt;br&gt;&#xA;  &lt;strong&gt;&lt;em&gt;(1) When over the high seas, comply with&#xA;  annex 2 (Rules of the Air) to the Convention on International Civil&#xA;  Aviation and with Secs. 91.117(c), 91.127, 91.129, and 91.131;&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;  (2) When within a foreign country, comply with the regulations relating to&#xA;  the flight and maneuver of aircraft there in force;&lt;br&gt;&#xA;  [(3) Except for&#xA;  Sec. Sec. 91.117(a), 91.307(b), 91.309, 91.323, and 91.711, comply&#xA;  with this part so far as it is not inconsistent with applicable&#xA;  regulations of the foreign country where the aircraft is operated or&#xA;  annex 2 of the Convention on International Civil Aviation; and]&lt;br&gt;&#xA;  (4) When operating within airspace designated as Minimum Navigation&#xA;  Performance Specifications (MNPS) airspace, comply with Sec. 91.705.&#xA;  When operating within airspace designated as Reduced Vertical&#xA;  Separation Minimum (RVSM) airspace, comply with Sec. 91.706.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Annex&#xA;  2 to the Convention on International Civil Aviation, Ninth&#xA;  Edition--July 1990, with Amendments through Amendment 32 effective&#xA;  February 19, 1996, to which reference is made in this part, is&#xA;  incorporated into this part and made a part hereof as provided in 5&#xA;  U.S.C. Sec. 552 and pursuant to 1 CFR part 51. Annex 2 (including a&#xA;  complete historic file of changes thereto) is available for public&#xA;  inspection at the Rules Docket, AGC-200, Federal Aviation&#xA;  Administration, 800 Independence Avenue SW., Washington, DC 20591; or&#xA;  at the Office of the Federal Register, 800 North Capitol Street, NW.,&#xA;  Suite 700, Washington, DC. In addition, Annex 2 may be purchased from&#xA;  the International Civil Aviation Organization (Attention: Distribution&#xA;  Officer), P.O. Box 400, Succursale, Place de L'Aviation&#xA;  Internationale, 1000 Sherbrooke Street West, Montreal, Quebec, Canada&#xA;  H3A 2R2.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atbarc/99-3.HTM&quot;&gt;Another unrelated FAA document&lt;/a&gt; explains it in plain language:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;International Civil Aviation Organization (ICAO)&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ICAO is an agency of the United Nations that originated from the&#xA;  signing of the Convention on International Civil Aviation in December&#xA;  1944 (referred to as the Chicago Convention). This organization was&#xA;  formed to promote the safe and orderly development of international&#xA;  civil aviation. The Chicago Convention produced International&#xA;  Standards and Recommended Practices (SARP) aimed at standardizing&#xA;  international civil aviation operational practices and services.&#xA;  Currently, these SARP's are contained in 18 annexes to the Chicago&#xA;  Convention. In particular, Annex 2, Rules of the Air, and Annex 11,&#xA;  Air Traffic Services, are pertinent to this paper as they relate to&#xA;  civil aircraft operations, the establishment of airspace, and air&#xA;  traffic control (ATC) services in international airspace. Although not&#xA;  addressed in this paper, it should be noted that the SARP's are&#xA;  augmented by various ICAO documents containing Procedures for Air&#xA;  Navigation Services (PANS) that amplify the basic principles in the&#xA;  SARP's. Further, to supplement the worldwide procedures contained in&#xA;  the annexes and PANS, ICAO develops Regional Supplementary Procedures,&#xA;  which are part of the Air Navigation Plans agreed upon to meet the&#xA;  needs of specific geographical areas.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Two articles of the Chicago Convention also have a bearing on the&#xA;  subject of this paper:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Article 3:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Exempts state-owned aircraft (which includes military aircraft) from&#xA;  the provisions of Annex 11 and its Standards and Recommended&#xA;  Practices. (Note: As an ICAO Contracting State, the U.S. has agreed&#xA;  that its state aircraft will be operated in international airspace&#xA;  with due regard for the safety of civil aircraft.)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Article 12:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Obligates each ICAO Contracting State to adopt measures to insure that&#xA;  persons operating an aircraft within its territory shall comply with&#xA;  that state's air traffic rules; or with Annex 2, Rules of the Air,&#xA;  when operating over the high seas. The U.S. satisfied this&#xA;  responsibility through Title 14, Code of Federal Regulations (CFR)&#xA;  Part 91 which requires that operators of aircraft comply with U.S.&#xA;  operating rules when in the U.S., and that U.S.-registered aircraft&#xA;  comply with Annex 2 when over the high seas (see section 91.703).&#xA;  However, section 91.703 applies only to civil aircraft, and state&#xA;  aircraft operating outside the U.S. are only subject to the &quot;due&#xA;  regard&quot; provisions of Article 3 of the Convention.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Under ICAO agreements, the SARP's in Annex 11 apply to airspace under&#xA;  the jurisdiction of a contracting state which has accepted the&#xA;  responsibility of providing air traffic services over the high seas,&#xA;  or in airspace of undetermined sovereignty.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-21T23:41:58.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1226" PostTypeId="2" ParentId="1210" CreationDate="2014-01-21T23:53:47.023" Score="9" Body="&lt;p&gt;Let me give you a brief description of all the authorities you mentioned (as far as I know them). I hope this will help you and answers your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO&lt;/strong&gt; - The International Civil Aviation Organization is was founded to set up international standards in aviation. When international air travel became more and more present (1947) there was a need have international regulations. The ICAO counts 191 member states and all have to adopt their guidelines or advice the ICAO of regional differences, which will then published by the ICAO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FAA&lt;/strong&gt; The Federal Aviation Administration is the aviation authority of the United States of America. It is responsible for setting up the federal aviation regulations (FAR), which are binding for all flight operations in the US. The FAA also provides air traffic control service at most control towers and all en-route air traffic control centers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EASA&lt;/strong&gt; - The European Aviation Safety Agency, former Joint Aviation Authority (JAA), is best described by taking both names: It's the European aviation authority. I personally (on my license it still says JAA) don't see the advantages of EASA compared to JAA. I've heard that they are aiming for a 'Single European Sky', which I would really appreciate, but it also costs a lot of money and means a bunch of new paperwork. Let's return to your question as an authority you can compare EASA to the FAA, but you need to remember that it is still an international and organization, so even if they are small, there are regional differences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CAA&lt;/strong&gt; - Honestly I don't even know what the abbreviation stands for, but as far as I know it's the Chinese aviation authority and a governmental organization of the republic of China. It's also Civil Aviation Authority for UK. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you see, all of them are there to establish rules for aviation in order to make it as safe and efficient as possible. The ICAO is international and responsible for very basic - they are still complex - general rules. The other authority are making there regulations according to, or at least, based on the ICAO standards.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="-1" LastEditDate="2016-07-09T12:09:02.870" LastActivityDate="2016-07-09T12:09:02.870" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1227" PostTypeId="2" ParentId="60" CreationDate="2014-01-22T00:34:02.547" Score="-2" Body="&lt;p&gt;Another good general rule &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Everything the weather man tells you it's true ... the rest is magnetic&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-22T00:34:02.547" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1228" PostTypeId="2" ParentId="1199" CreationDate="2014-01-22T00:39:42.197" Score="0" Body="&lt;p&gt;Regulations are somewhat different for different aircraft (airplane, helicopter, glider, etc). I'll assume the question asks about private pilot for single-engine land-based aircraft (SEL).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the United States, answer can be found in FAR §61 subpart E. Applicable sections are: 103(a),(c)-(j), 105, 107(a),(b)(1), 109(a).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1e34acc0646cdf8bf39113d9728a7a4a&amp;amp;node=14:2.0.1.1.2.5&amp;amp;rgn=div6&quot; rel=&quot;nofollow&quot;&gt;FAR §61, Subpart E&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: not a lawyer, just a humble student pilot navigating this gauntlet himself :-).&lt;/p&gt;&#xA;" OwnerUserId="540" LastActivityDate="2014-01-22T00:39:42.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1229" PostTypeId="2" ParentId="1219" CreationDate="2014-01-22T01:31:21.873" Score="16" Body="&lt;p&gt;Perhaps instead of thinking of a single primary means of slowing a large jet, we should think about a primary means for a given set of conditions, the combinations of which are numerous. To mention a few: What is the weight of the aircraft. Passenger aircraft are typically nowhere near max landing weight when they land. Freighters are often loaded such that they may be very close (or even over truth be told) to max landing weight. Is the aircraft going to be on the ground a sufficient time for brakes heated to their max to cool? Was the leg from which you are landing long enough to allow the brake and tire energy from the taxi and takeoff to dissipate? Is where you're landing used to having to handle hot brakes and thus can be expected to have a huffer readily available to cool them and people who know how to do it? Do you have a reverser locked out for maintenance. Does your next departure allow for safely leaving the gear down for awhile and thus gave you more leeway on heating the brakes when you landed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just some thoughts.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-01-22T01:31:21.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1230" PostTypeId="2" ParentId="1219" CreationDate="2014-01-22T10:19:53.550" Score="2" Body="&lt;p&gt;While landing you want to reduce speed for which you need spoilers and to have more lift and drag you have the Flaps deployed than just when you touch down on runway ground spoilers are deployed. If want to land with short runway length then you go for reverse thrust (nice to have in normal scenario but in case of emergency it can be a life-saver). Then we need wheel brakes to stop the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effectiveness:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When in air/near ground: only spoilers/Flaps and airbrake (ground spoilers) are effective to reduce speed of aircraft but not to stop it&lt;/li&gt;&#xA;&lt;li&gt;Flap are required to keep the aircraft in a configuration such that you don't crash on ground&lt;/li&gt;&#xA;&lt;li&gt;When on ground: you still have airbrakes/spoilers effective when aircraft speed is high but its effectiveness decreases at low speed. So, are other control surfaces useless @ low speed (Flaps/Spoilers etc). Reverse thrust and wheel brakes are the one you can rely on. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Failures:&#xA;All critical systems on aircraft have redundancy so the probabilty of failure is around 1e-8 /flight-hr but still you never know. I think you will be able to land but you need more runway length in case of two fail scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, I believe you can land without wheel brakes by using reverse thrust but purpose of reverse thrust is only to reduce aircraft speed such that we land on short runway. so, its not recommended to not use wheel brakes and use reverse thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slick runway/rain or snow on runway has same effect as it has on other land vehicles.. Aircraft will take more runway length than usual.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="72" LastEditDate="2014-01-22T11:56:05.097" LastActivityDate="2014-01-22T11:56:05.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1231" PostTypeId="1" AcceptedAnswerId="1235" CreationDate="2014-01-22T10:48:59.280" Score="9" ViewCount="2716" Body="&lt;p&gt;I know that historically pilots used to trim an aircraft to relieve continuous application of force during climb/cruise/descent, and at that trim tabs existed on control surfaces (elevator, ailerons, etc) which could be used to hold the position of the control surface without the pilot applying any force. But now, we don't usually have trim tabs, and with fly-by-wire systems forces have been reduced on the pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does trimming do anything other than reduce pilot workload? Also:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Do modern aircraft still follow this concept of trim to reduce pilot's continuous force on the flight controls?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Apart from pilot workload and fuel efficiency (I know that trimming an aircraft can produce drag), what other benefits does trim offer?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Without trim tabs, how is trimming accomplished?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="685" LastEditorUserId="39" LastEditDate="2014-01-22T17:30:02.690" LastActivityDate="2017-08-21T12:30:34.287" Title="Is trimming aircraft to relieve pilot of applying force on control stick/Pedal still applicable?" Tags="&lt;flight-controls&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1232" PostTypeId="2" ParentId="1231" CreationDate="2014-01-22T12:28:12.403" Score="1" Body="&lt;p&gt;Trim still exists on new airplanes.   I don't know where you got the idea that planes don't have trim tabs, or that FBW eliminated this.  Any sources or evidence to support your claim?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(&lt;a href=&quot;http://www.wired.com/autopia/2012/07/boeing-787-dreamliner-flight/#slideid-131441&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; describes the trim of the 787)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-22T12:28:12.403" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1233" PostTypeId="2" ParentId="1231" CreationDate="2014-01-22T15:30:03.183" Score="2" Body="&lt;p&gt;Trims function is to balance the downward directed lift from the horizontal stab against the upward directed lift from the wing.  Obviously, the lift generated by the wing varies with airspeed, and as a consequence we trim for an airspeed.  The other consequence is we trim for 0 control column/stick deflection, that is to say the balance of forces we trim for assumes no control input.  We do this for stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The perception we get from that is that we trim to reduce control forces, and while that conclusion is true, I argue that it is a consequence to what we are really doing.  With that said, the control column force reduction is absolutely essential, particularly when flying a high performance airplane capable of a wide range of speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For FBW systems, the need to balance the lift on the trim and wing is still necessary and so the need for trim still exists.  The trim won't have an impact on control forces in this case, but will adjust the need for deflection of the stick just as in a traditional control column or stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For larger airplanes without a trim tab, the horizontal stabilizer becomes a &lt;strong&gt;horizontal stabilator&lt;/strong&gt; in which the entire horizontal surface moves.  The whole surface rotates to change its angle of attack and the associated change in lift is how trim is accomplished.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the other trims (aileron and rudder) in larger airplanes these can be implemented in the hydraulic actuators that actually move those control surfaces. These would cause a constant offset deflection from the control input.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-22T15:35:28.017" LastActivityDate="2014-01-22T15:35:28.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1234" PostTypeId="2" ParentId="1224" CreationDate="2014-01-22T15:51:22.210" Score="2" Body="&lt;p&gt;You can find lots of information on RVSM at &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/documentation/&quot; rel=&quot;nofollow&quot;&gt;this FAA website&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/documents/FAQ_AIR_Aug_10.doc&quot; rel=&quot;nofollow&quot;&gt;This MSWord document&lt;/a&gt; found on that site:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Operational Approval or Authorization.   The FSDO or CMO will grant operational approval or authorize the operator to conduct RVSM operations by issuing Operations Specifications paragraphs B046 and D092 to air carriers or issuing a Letter of Authorization (LOA) to general aviation operators, as appropriate.  Individual operator RVSM-compliant airframes are listed in D092 or on the LOA, as appropriate.  The FSDO or CMO will take this action after it has determined that the operator’s aircraft are RVSM compliant; it has approved the operator’s RVSM maintenance program; a CMO has approved or a FSDO has accepted the operations programs and the office has accepted the operator’s plan for participation in the monitoring program. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/aircraft_certification/&quot; rel=&quot;nofollow&quot;&gt;This Excel spreadsheet&lt;/a&gt; lists points of contact at various FSDOs.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-22T15:51:22.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1235" PostTypeId="2" ParentId="1231" CreationDate="2014-01-22T15:54:20.100" Score="18" Body="&lt;p&gt;Almost all &lt;strong&gt;airplanes&lt;/strong&gt; have &lt;em&gt;trim&lt;/em&gt; (I'm fairly certain that the Wright Flyer didn't, so I can't say &lt;em&gt;all&lt;/em&gt; airplanes do), but a lot of newer designs don't use &lt;em&gt;trim tabs&lt;/em&gt; because they are less aerodynamically efficient than alternative designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, the Falcon 50 &amp;amp; 900 that I fly doesn't have a single trim tab on it.  Normally the flight controls are moved by hydraulics and a small electrical actuator is used to adjust the position of the aileron and rudder for trim purposes.  Pitch trim is accomplished by moving the front of the entire horizontal stabilizer in order to adjust the angle and amount of lift produced by the tail.  This is done so that the elevator can be neutralized and not create the additional drag caused by being in the airflow.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On FBW airplanes, they may or may not have manual trim that is used (under normal circumstances) by the pilot.   Trimming is still taking place on FBW airplanes without manual trim, but it is simply automated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing typically designs their FBW airplanes so that they behave like a &quot;normal&quot; airplane, and require the pilot to trim in order to relieve the control forces.  This is all completely artificial though, programmed simply to give feedback to the pilot.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus on the other hand doesn't give any feedback to the pilot through the side stick so there are no control forces to relieve.   When you release the side stick, it centers and the aircraft maintains its current pitch and bank angle.  In this case, the autopilot automatically trims the airplane for the current conditions, and the pilot doesn't need to worry about it.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-22T17:20:41.837" LastActivityDate="2014-01-22T17:20:41.837" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1236" PostTypeId="2" ParentId="1223" CreationDate="2014-01-22T16:10:54.700" Score="10" Body="&lt;p&gt;The biggest risk is improper execution.  If you build up too much airspeed and pull out of the dive at 4-G and break something, that will be your primary issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your secondary risks will be associated with the fuel and oil system starvation if they depend on gravity for operation.  This risk is balanced by how long you can sustain 0-g flight.  Oil issues are bigger risk than fuel, as even if you did sustain 0-g long enough to starve the engine, you should get it back as soon as you are in positive G.  This particular risk will vary by airplane and I probably can't say something as general as &quot;not typically a problem for short duration 0-g excursions&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An additional secondary risk is unsecured objects in the cockpit.  This presents a number of possible complications:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;floating objects may distract you from aviating&lt;/li&gt;&#xA;&lt;li&gt;floating objects may break something (the example of a window in the cockpit would cause a major distraction for the remainder of flight)&lt;/li&gt;&#xA;&lt;li&gt;Most importantly, this can change your CG which can have dire consequences if something heavy enough gets moved far enough.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I wouldn't put risk of stall too high on the list, because you should be doing this with enough altitude and in coordinated flight so a stall would just be a simple recovery.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for whether this is an aerobatic maneuver, it is a lot like a departure stall but a botched recovery (pushing over to 0-g before the stall breaks) and only a passenger could say for sure what you were actually doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That leads into the last risk I can think of, and that is when your passenger deposits his/her lunch all over the airplane.  In 0-g that could get on the windscreen and obscure your vision.  Be careful!&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-22T16:48:30.723" LastActivityDate="2014-01-22T16:48:30.723" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1237" PostTypeId="2" ParentId="1223" CreationDate="2014-01-22T16:17:49.883" Score="7" Body="&lt;p&gt;I did quite a number of zero gravity manoeuvres on a Cessna Citation II, not as a pilot but as an experiment coordinator. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine lubrication was gravity based on that aircraft, and zero-g caused a Master Caution / oil pressure warning. Since the zero gravity manoeuvres lasted only for about 12 seconds, this wasn't a problem according to the engine manufacturer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Entry and recovery caused extra g-forces on the airframe, I remember we reached 2.5g during pull up. Especially the recovery out of the parabolic flight was tricky, balancing between duration of the zero-g segment, g-force during pull up and overspeed. Sometimes spoilers were deployed at the end of the parabolic section to keep the speed down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There isn't much risk of stall, since the higher wing loading occurs at quite a high speed, keeping the required lift coefficient low. The low speed segment on top of the parabola is a zero g, so no stalling there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another serious risk is getting hit by things flying around the cockpit and cabin when negative G is accidentally achieved. Flight manuals crashing into your head at 2.5g during the pull up are no fun. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Negative G's are also a risk for the fuel system when it is purely gravity based. If air bubbles get trapped inside the fuel line it can cause engine stall. I think this is less of a problem in jet / turbine engines which seem to have fuel pumps in any case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Citation II negative G s caused a spray of fuel from the vents in the wing tip;  spectacular but harmless. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-22T16:17:49.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1238" PostTypeId="1" CreationDate="2014-01-22T17:39:36.147" Score="17" ViewCount="19505" Body="&lt;p&gt;In the Chart Supplement there is occasionally a &lt;code&gt;‡&lt;/code&gt; symbol after the operating hours for control towers (and other time information) like what's shown below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/913KW.png&quot; alt=&quot;AFD snapshot&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does the ‡ symbol represent?&lt;/p&gt;&#xA;" OwnerUserId="687" LastEditorUserId="62" LastEditDate="2016-10-07T17:24:36.413" LastActivityDate="2016-10-07T17:24:36.413" Title="What does the ‡ symbol in the Chart Supplement (A/FD) designate?" Tags="&lt;flight-training&gt;&lt;chart-supplement&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1239" PostTypeId="2" ParentId="1238" CreationDate="2014-01-22T17:44:58.743" Score="15" Body="&lt;p&gt;The ‡ symbol in the A/FD specifies that the location observes daylight savings time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is from the A/FD legend, which can be found online by going to the &lt;a href=&quot;http://aeronav.faa.gov/index.asp?xml=aeronav/applications/d_afd&quot; rel=&quot;noreferrer&quot;&gt;online digital A/FD&lt;/a&gt; and searching for an airport.  The &lt;em&gt;A/FD Legend&lt;/em&gt; link will then be at the top of the search results (unfortunately the link changes every cycle so I can't include an exact link).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;6 TIME CONVERSION&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Hours of operation of all facilities are expressed&#xA;  in Coordinated Universal Time (UTC) and shown as ‘‘Z’’ time. The&#xA;  directory indicates the number of hours to be subtracted from UTC to&#xA;  obtain local standard time and local daylight saving time UTC–5(–4DT).&#xA;  &lt;strong&gt;&lt;em&gt;The symbol ‡ indicates that during periods of Daylight Saving Time&#xA;  effective hours will be one hour earlier than shown.&lt;/em&gt;&lt;/strong&gt; In those areas&#xA;  where daylight saving time is not observed the (–4DT) and ‡ will not&#xA;  be shown. Daylight saving time is in effect from 0200 local time the&#xA;  second Sunday in March to 0200 local time the first Sunday in&#xA;  November. Canada and all U.S. Conterminous States observe daylight&#xA;  saving time except Arizona and Puerto Rico, and the Virgin Islands. If&#xA;  the state observes daylight saving time and the operating times are&#xA;  other than daylight saving times, the operating hours will include the&#xA;  dates, times and no ‡ symbol will be shown, i.e., April 15–Aug 31&#xA;  0630–1700Z, Sep 1–Apr 14 0600–1700Z.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-13T05:15:47.693" LastActivityDate="2014-02-13T05:15:47.693" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1240" PostTypeId="1" AcceptedAnswerId="1241" CreationDate="2014-01-22T18:34:06.333" Score="6" ViewCount="219" Body="&lt;p&gt;As a numbers/statistics geek I would like to be able to look up information on how &quot;busy&quot; particular airports or regions are.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure the FAA collects this data, but is it accessible to the general public?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-22T18:46:32.647" Title="Where can I get information on ATC facility activity, like the number of flights handled in a month?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="0" CommunityOwnedDate="2014-01-22T18:34:06.333" ContentLicense="CC BY-SA 3.0" />
  <row Id="1241" PostTypeId="2" ParentId="1240" CreationDate="2014-01-22T18:34:06.333" Score="5" Body="&lt;p&gt;The FAA's &lt;a href=&quot;http://aspm.faa.gov/opsnet/sys/Main.asp&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Activity Data System (ATADS)&lt;/a&gt; contains broad statistical information on activity in the national airspace system which can be used to get an idea of how &quot;busy&quot; a particular Center, TRACON, or Tower facility is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The caveat is this data only encompasses aircraft talking to Air Traffic Control, so it &lt;em&gt;won't&lt;/em&gt; be able to tell you anything about uncontrolled fields except possibly what you can glean from Center/TRACON activity information for the greater area.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'm not sure where they get their data from, but &lt;a href=&quot;http://www.fltplan.com/AwMainSearchToAirportID.exe?a=1&quot; rel=&quot;noreferrer&quot;&gt;Fltplan.com&lt;/a&gt; has annual reported data for each airport in their &lt;em&gt;Airports &amp;amp; FBO's&lt;/em&gt; database:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, this is for KBRY (which is uncontrolled):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wj3vf.png&quot; alt=&quot;KBRY Aircraft Data&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="69" LastEditDate="2014-01-22T18:46:32.647" LastActivityDate="2014-01-22T18:46:32.647" CommentCount="0" CommunityOwnedDate="2014-01-22T18:34:06.333" ContentLicense="CC BY-SA 3.0" />
  <row Id="1242" PostTypeId="1" AcceptedAnswerId="1243" CreationDate="2014-01-22T18:43:45.813" Score="5" ViewCount="746" Body="&lt;p&gt;Most GA piston aircraft still use dual magnetos for their ignition system, but there are some &lt;a href=&quot;http://www.electroair.net/stc_ignition_kit.html&quot; rel=&quot;nofollow&quot;&gt;STC kits available to add electronic ignition to common piston engines&lt;/a&gt;, and new aircraft often come with &lt;a href=&quot;http://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;FADEC&lt;/a&gt; systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there particular FAA requirements for electronic ignition systems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what are they and how can you demonstrate compliance?&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="97" LastEditDate="2014-03-21T04:02:19.083" LastActivityDate="2014-03-21T04:02:19.083" Title="What FAA requirements exist for electronic ignition systems on piston engines?" Tags="&lt;faa-regulations&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1243" PostTypeId="2" ParentId="1242" CreationDate="2014-01-22T19:52:45.777" Score="5" Body="&lt;p&gt;The ignition requirements are pretty straight-forward:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#14:1.0.1.3.10.5.97.75&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;§23.1165   Engine ignition systems.&lt;/strong&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Each battery ignition system must be supplemented by a generator&#xA;  that is automatically available as an alternate source of electrical&#xA;  energy to allow continued engine operation if any battery becomes&#xA;  depleted.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The capacity of batteries and generators must be large enough to&#xA;  meet the simultaneous demands of the engine ignition system and the&#xA;  greatest demands of any electrical system components that draw from&#xA;  the same source.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The design of the engine ignition system must account for—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The condition of an inoperative generator;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The condition of a completely depleted battery with the generator&#xA;  running at its normal operating speed; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The condition of a completely depleted battery with the generator&#xA;  operating at idling speed, if there is only one battery.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) There must be means to warn appropriate crewmembers if&#xA;  malfunctioning of any part of the electrical system is causing the&#xA;  continuous discharge of any battery used for engine ignition.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Each turbine engine ignition system must be independent of any&#xA;  electrical circuit that is not used for assisting, controlling, or&#xA;  analyzing the operation of that system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) In addition, for commuter category airplanes, each turbine engine&#xA;  ignition system must be an essential electrical load.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-22T19:52:45.777" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1244" PostTypeId="2" ParentId="1231" CreationDate="2014-01-22T20:33:27.243" Score="2" Body="&lt;p&gt;In reference to item 1 of the question, it's not only to reduce the pilot's continuous force on the flight controls but also that of the autopilot. For example, you're straight and level with the autopilot holding altitude, and as the flight progresses your center of gravity is moving forward due to fuel burn. The autopilot compensates with an up-elevator force. On 747-100s -200s there's a gauge that shows you how much up-elevator the autopilot is commanding. So, if you're about to disengage the autopilot, you'd best glance down at that gauge to anticipate the control force you're going to need. If you're in cruise, you may still want to keep an eye on it and add appropriate trim manually to save a little fuel. If you're lazy, you can ignore it, and when the up-elevator requirement reaches a certain point, the autopilot will trim it out.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-01-22T20:33:27.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1245" PostTypeId="1" CreationDate="2014-01-22T21:50:13.640" Score="10" ViewCount="2385" Body="&lt;p&gt;In a multi-engine airplane, if an engine failure occurs at the exact moment that a decision needs to be made to reject or continue the takeoff, and there is plenty of runway available to do either, which one is statistically safer?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more technical way to ask the same question would be:  When there is sufficient runway available, is it better to artificially increase $V_1$ (via an assumed temperature takeoff or similar approved procedure) in order to stay on the runway longer in case an abort is required, or would it be better to leave $V_1$ at the lower speed and take any problems into the air?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="247" LastEditDate="2014-07-07T05:41:57.230" LastActivityDate="2014-07-07T05:41:57.230" Title="During a takeoff emergency, is it safer to abort or continue the takeoff if either can be done within the available runway?" Tags="&lt;safety&gt;&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;multi-engine&gt;&lt;engine-failure&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1246" PostTypeId="1" AcceptedAnswerId="1248" CreationDate="2014-01-22T22:01:43.467" Score="16" ViewCount="8885" Body="&lt;p&gt;I was looking at &lt;a href=&quot;http://www.gelib.com/aeronautical-charts-united-states.htm&quot;&gt;http://www.gelib.com/aeronautical-charts-united-states.htm&lt;/a&gt;, where you can download shape files for Google Earth that show US airspaces.  I'm writing some software that has a similar need and need to find a source for this data.  I'm looking for data that defines the extents of airspaces including MOAs, restricted areas, etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been pouring through the FAA's website with no luck.  The link I referenced above says its source was the National Aeronautical Charting Office (NACO), which I'm having very little luck finding as well.  I think it may have been renamed, thus the poor results.  I also called the FAA and can't seem to find anyone there that knows where to transfer me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, does anyone here have any helpful pointers on finding said information?  I want to pull it directly from the source to make sure it is always up-to-date and accurate.&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="62" LastEditDate="2014-01-23T13:36:22.140" LastActivityDate="2021-03-07T23:19:23.997" Title="Where can I get the FAA data that defines airspace, including MOAs etc.?" Tags="&lt;faa&gt;&lt;airspace&gt;&lt;aeronautical-charts&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1247" PostTypeId="2" ParentId="1246" CreationDate="2014-01-22T22:14:20.500" Score="3" Body="&lt;p&gt;You are looking for Aeronautical Navigation Products (&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/&quot; rel=&quot;nofollow&quot;&gt;AeroNav Products&lt;/a&gt;) (formerly NACO).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They have a number of digital products, which should have the data that you are looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, their &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/&quot; rel=&quot;nofollow&quot;&gt;contact information&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Customer Service:  (800) 626-3677&lt;br&gt;&#xA;  9-AMC-Aerochart@faa.gov  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Abigail &quot;Abby&quot; Smith, Director&lt;br&gt;&#xA;  FAA, AeroNav Products AJV-3&lt;br&gt;&#xA;  1305 East-West Hwy&lt;br&gt;&#xA;  Silver Spring, MD 20910&lt;br&gt;&#xA;  (301) 427-5000&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-22T22:22:13.693" LastActivityDate="2014-01-22T22:22:13.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1248" PostTypeId="2" ParentId="1246" CreationDate="2014-01-22T22:34:16.163" Score="13" Body="&lt;p&gt;Take a look at the &lt;a href=&quot;https://nfdc.faa.gov/xwiki/bin/view/NFDC/WebHome&quot; rel=&quot;nofollow noreferrer&quot;&gt;National Flight Data Center&lt;/a&gt;.  The data appears to be contained in &lt;a href=&quot;https://nfdc.faa.gov/xwiki/bin/view/NFDC/56+Day+NASR+Subscription&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASR&lt;/a&gt;. I mentioned in my comment that there may be no official source for spatial data, but I think this may include what you are looking for.&lt;/p&gt;&#xA;&lt;p&gt;These are derived products. The cannonical definitions are the legal descriptions found in FAA Orders with the prefix 7400. At the time of this writing, &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1038054&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7400.11 (current version E)&lt;/a&gt; covered airspace classes A,B,C,D and E as well as reporting points. The &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1039057&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7400.10 (current version C)&lt;/a&gt; covered special use airspaces. Both publications can be found at the &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA's Website&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="54557" LastEditDate="2021-02-23T22:54:23.977" LastActivityDate="2021-02-23T22:54:23.977" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="1249" PostTypeId="2" ParentId="1218" CreationDate="2014-01-22T23:05:56.313" Score="9" Body="&lt;p&gt;I finally found an &lt;a href=&quot;http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Process-Brief-Criteria-For-Establishing-Air-Traffic-Control-Towers-and-the-Contract-Tower-Program.aspx&quot;&gt;AOPA article&lt;/a&gt; that discusses requirements for a control tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA has the authority to establish control towers or discontinue&#xA;  control tower services through the National Airspace System when&#xA;  activity levels and safety considerations merit such action.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In order to open a new tower, there must be a positive Benefit-Cost ratio (which is a complicated thing to calculate).  The FAA typically pays for the cost, and here is the criteria that they list:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Criteria&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;According to FAR Part 170.13, the following criteria, along with&#xA;  general facility establishment standards, must be met before an&#xA;  airport can qualify for a control tower:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The airport, whether publicly or privately owned, must be open to and available for use by the public as defined in the Airport and&#xA;  Airway Improvement Act of 1982;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The airport must be part of the National Plan of Integrated Airport Systems;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The airport owners/authorities must have entered into appropriate assurances and covenants to guarantee that the airport will continue&#xA;  in operation for a long enough period to permit the amortization of&#xA;  the control tower investment;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The FAA must be furnished appropriate land without cost for construction of the control tower; and&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The airport must meet the benefit-cost ratio criteria specified herein utilizing three consecutive FAA annual counts and projections&#xA;  of future traffic during the expected life of the tower facility. (An&#xA;  FAA annual count is a fiscal year or a calendar year activity summary.&#xA;  Where actual traffic counts are unavailable or not recorded,&#xA;  adequately documented FAA estimates of the scheduled and nonscheduled&#xA;  activity may be used.)&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;The FARs specifically state that an airport is not guaranteed to&#xA;  receive a control tower, even if the airport meets all the criteria&#xA;  listed above. This is where the contract tower program comes in. The&#xA;  FAA, responding to an airport sponsor's request for an air traffic&#xA;  control tower, can elect to establish a contract tower. The FAA can&#xA;  either elect to pay for the service in its entirety, or enter into a&#xA;  cost-sharing agreement with the sponsor, depending on the results of&#xA;  the benefit-cost analysis. Typically, the airport sponsor is&#xA;  responsible for 10 percent of the cost of construction and operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For the Benefit-Cost calculation, they use the following criteria:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Site-specific activity forecasts are used to estimate three categories&#xA;  of tower benefits:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Benefits from prevented collisions between aircraft.&lt;/li&gt;&#xA;  &lt;li&gt;Benefits from other prevented accidents.&lt;/li&gt;&#xA;  &lt;li&gt;Benefits from reduced flying time.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;Explicit dollar values are assigned to the prevention of fatalities&#xA;  and injuries and time saved.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Tower establishment costs include:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Annual operating costs: staffing, maintenance, equipment, supplies, and leased services.&lt;/li&gt;&#xA;  &lt;li&gt;Investment costs: facilities, equipment, and operational start-up.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article contains a lot more information, along with links to the relevant regulations, etc.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-22T23:05:56.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1250" PostTypeId="2" ParentId="1245" CreationDate="2014-01-23T02:14:56.147" Score="7" Body="&lt;p&gt;The best answer I can provide is &lt;em&gt;it depends&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an emergency involving flight controls, trim runaways, pitch trim fail, full hydraulic failure, or a windshear indication, if the remaining runway was what I knew I could land and rollout on, I would abort the takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all other emergencies including engine failure and/or fire, I would takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is how I briefed my FO when I was a captain and similar to how my captains briefed me when I was an FO.  The most common verbiage other captains used was &quot;I'll abort after $V_1$ for failure to fly&quot;, and I consider the specific scenarios I mention to meet that criteria for the EMB-145.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll also explicitly say that I consider the aborts I listed to be safer than to takeoff:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;flight controls - for obvious reasons&lt;/li&gt;&#xA;&lt;li&gt;trim runaways - an out of trim transport category airplane can be a beast to fly&lt;/li&gt;&#xA;&lt;li&gt;pitch trim fail - in the EMB-145 a re-trim from &quot;8 up&quot; to &quot;6 up&quot; has to happen at pretty slow airspeeds after takeoff or the aerodynamic forces on the stab will overcome the trim motor.&lt;/li&gt;&#xA;&lt;li&gt;full hydraulic failure - we did it in the sim and it is a two person job to manhandle the controls, not particularly fun.&lt;/li&gt;&#xA;&lt;li&gt;windshear indication - low and slow and performance decreasing windshear means you'll probably be back on the ground anyway.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I would consider aborting, given a long enough runway, to be safer than taking off for these scenarios.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="97" LastEditDate="2014-04-17T00:04:35.890" LastActivityDate="2014-04-17T00:04:35.890" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1251" PostTypeId="1" AcceptedAnswerId="1254" CreationDate="2014-01-23T02:22:49.467" Score="7" ViewCount="1846" Body="&lt;p&gt;This is what I know: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$V_1$ is the takeoff airspeed after which the aircraft &lt;strong&gt;must&lt;/strong&gt; take off, no matter what happens after $V_1$ has been reached. That's the easy part (I think).&lt;/li&gt;&#xA;&lt;li&gt;$V_R$ is the rotation airspeed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there any other $V$-speeds?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm specifically curious about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is $V_1$ related to runway length? &lt;/li&gt;&#xA;&lt;li&gt;Is there an absolute maximum $V_1$ for each aircraft type? If so, can it vary based on conditions (takeoff weight, density altitude, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Are there circumstances where $V_1$ is higher than $V_R$? If so, does that mean that $V_1$ is never called on a normal takeoff? (this is the case for most light aircraft, but I guess the whole concept is not applicable in that case)&lt;/li&gt;&#xA;&lt;li&gt;What exactly is $V_2$?&lt;/li&gt;&#xA;&lt;li&gt;Is there a $V_3$? (and so on)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Anything else worth knowing about $V$-speeds?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="97" LastEditDate="2014-04-16T23:44:07.790" LastActivityDate="2014-06-19T21:06:02.947" Title="What are the V-Speeds used during a normal takeoff in a multi-engine airplane?" Tags="&lt;takeoff&gt;&lt;multi-engine&gt;&lt;v-speeds&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1252" PostTypeId="2" ParentId="1245" CreationDate="2014-01-23T02:23:58.960" Score="18" Body="&lt;p&gt;In my experience, admittedly dated (retired 1999) whether it's 'better' or not didn't enter into the consideration. A reduced-power assumed-temperature was always used (unless there was something that prohibited it) because of the cost factor, and the power reduction used was always such that there was the proper amount of runway but not 'plenty' of runway. There was a maximum amount of reduction above which you could not legally go, but that was rarely used in my experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that said, it's the captain's airplane. While I was a 747 f.o., I occasionally saw captains use less than the power reduction called for. More often, but still not a lot, I saw captains simply call for a max power takeoff rather fussing with adjusting the reduced power. Max power takeoffs were always entered into the aircraft maintenance log because it was required to do one every so often. I forget the exact requirement..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I was a captain, I almost always observed the recommended reduced power. Twice doing this it became a closer thing than I would have liked. The first time was on the reef runway at Honolulu. We were over 800,000 lbs, it was my leg, and we lifted off at the very end. I rotated a couple of knots or so early because the end seemed to be getting very close. I thought a lot about that takeoff and discussed it with a number of people. My view, and I think the consensus view was: beware of high-humidity reduced power takeoffs. Humid air is less dense than dry air, but the performance charts (at least the ones we used) didn't take that into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A year or so later at Dhahran, Saudi Arabia, we were bringing a full load of troops back from Desert Storm. Reduced power was called for, the humidity was very high, and it was the f.o.s leg. A little over half way down the runway I didn't like how it was looking, and called for max power. Discussing it later with the f.o. and the f.e., we had all come to the same conclusion at about the same time. I had simply been the first to verbalize. &lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-01-23T02:23:58.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1253" PostTypeId="2" ParentId="1251" CreationDate="2014-01-23T02:35:07.433" Score="2" Body="&lt;p&gt;Stretching my memory, but I'll try, and others can correct what I get wrong. Think 'balanced field length'. Given an engine failure, $V_1$ is that speed at which if you abort you will be able to stop at the very end of the runway. $V_1$ is that speed at which if you choose to fly you will lift off at the very end of the runway. $V_1$ is that speed which if you are above and you abort you will go off the end of the runway (Kalitta 747 freighter a few years back tried to abort at $V_1+30$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer the runway, the higher your $V_1$. Enough runway and $V_1$ can exceed $V_2$, but that doesn't mean anything because you're going to rotate at $V_2$. If you choose to stay on the runway after $V_2$, you begin moving into an area limited by max tire heating. Maybe you can say that max $V_1$ is the max tire speed? I don't know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can't remember a $V_3$.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="97" LastEditDate="2014-04-16T23:51:22.093" LastActivityDate="2014-04-16T23:51:22.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1254" PostTypeId="2" ParentId="1251" CreationDate="2014-01-23T02:40:17.280" Score="5" Body="&lt;p&gt;$V_1$ is &lt;strong&gt;takeoff decision speed&lt;/strong&gt;.  It is based upon:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Runway length&lt;/li&gt;&#xA;&lt;li&gt;Temperature&lt;/li&gt;&#xA;&lt;li&gt;Reduced thrust takeoff&lt;/li&gt;&#xA;&lt;li&gt;Takeoff weight&lt;/li&gt;&#xA;&lt;li&gt;Takeoff flap setting&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If $V_1$ is higher than $V_R$, then (as far as I am aware), $V_1$ will be adjusted to be the same as $V_R$.  You have to make the decision to takeoff by the time you rotate, so it does not make much sense to have $V_1$ higher than $V_R$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V_2$ is &lt;strong&gt;takeoff safety speed&lt;/strong&gt;.  During a one engine inop takeoff we would accelerate to and climb at this airspeed to our acceleration height (a height we could level off at and be safe from obstacles while we further accelerate).  We also referenced certain flap transitions on takeoff to $V_2$ (e.g. $V_2+15$ - flaps 0)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To address the rest of the question, $V_1$ and $V_2$ are primarily used in large aircraft.  In light twins you also need to be aware of $V_{MC}$.  $V_{MC}$ is the minimum controllable airspeed with an engine inop.  In particular you do not want to be slower than this airspeed during climbout in case of engine failure.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="97" LastEditDate="2014-04-16T23:46:59.083" LastActivityDate="2014-04-16T23:46:59.083" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1255" PostTypeId="1" AcceptedAnswerId="1305" CreationDate="2014-01-23T03:05:20.577" Score="9" ViewCount="15298" Body="&lt;p&gt;If someone decides to become a professional pilot - meaning an airline or business jet pilot in the USA - what does it cost to get the certifications and ratings and build enough hours to become employable? Let's assume that the person is starting from scratch and works through private, instrument, commercial and ATP qualifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking of a scenario where someone already has a career and income but decides to change to flying and is able to invest the necessary time and money. Of course this could include other commercial flying jobs along the way - like crop dusting or banner towing - but the idea would be to eventually reach a position that pays a decent salary. &quot;Decent&quot; isn't very precise but I mean something much higher than the low regional salaries mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/questions/777/why-are-regional-airline-wages-barely-above-federal-minimum-wage&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-30T22:55:24.947" Title="What does it cost to get an ATP certificate from scratch?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;airline-operations&gt;&lt;career&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1256" PostTypeId="1" AcceptedAnswerId="1307" CreationDate="2014-01-23T06:31:26.317" Score="7" ViewCount="14349" Body="&lt;p&gt;&lt;a href=&quot;http://chat.stackexchange.com/transcript/message/13343469#13343469&quot;&gt;Inspired by a discussion in chat&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most GA piston singles are powered by either Lycoming or Continental engines.&lt;br&gt;&#xA;The engine designs used by both manufacturers are broadly similar (4-cycle, horizontally-opposed, gasoline-powered, air-cooled), and they're both generally available with either carburetors or fuel injection, but I know they're not &quot;identical products&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some of the differences between the designs used by the two manufacturers, and what practical implications do those choices have for pilots?&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="19" LastEditDate="2017-01-25T14:20:11.763" LastActivityDate="2017-09-05T16:04:06.690" Title="What are the differences between Lycoming and Continental engine designs?" Tags="&lt;piston-engine&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1257" PostTypeId="1" AcceptedAnswerId="1275" CreationDate="2014-01-23T08:07:40.800" Score="17" ViewCount="3236" Body="&lt;p&gt;I remember back in the 90's that commercial planes would line up on the runway, stop, apply full power and then release the brake to take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I've been on flight where they've literally rolled from the taxiway straight onto the runway and then powered up without stopping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why has that changed? What were the reasons for the older style?&lt;/p&gt;&#xA;" OwnerUserId="682" LastEditorUserId="62" LastEditDate="2014-01-23T13:42:05.563" LastActivityDate="2014-01-23T19:48:05.963" Title="Are rolling takeoffs now more common than powering up while holding on the brakes?" Tags="&lt;airline-operations&gt;&lt;takeoff&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1258" PostTypeId="1" AcceptedAnswerId="1261" CreationDate="2014-01-23T09:24:32.493" Score="9" ViewCount="11564" Body="&lt;p&gt;Requirements for 'complex' airplane seem to vary between regulators and between pilots, so let's have this settled once and for all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the definition of a 'complex' airplane as defined by FAA and EASA?&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="69" LastEditDate="2014-02-20T09:27:39.640" LastActivityDate="2014-02-20T09:27:39.640" Title="What are the requirements for a 'complex' airplane?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;far-61&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1259" PostTypeId="1" AcceptedAnswerId="1272" CreationDate="2014-01-23T09:30:05.757" Score="24" ViewCount="2024" Body="&lt;p&gt;In larger aircraft, shallow, high-power approaches are performed as a matter of routine, but in light aircraft it seems to be frowned upon, especially in clear weather and smooth fields. Why is &quot;dragging it in&quot; considered bad in small aircraft?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-23T09:38:48.813" LastActivityDate="2018-02-21T01:36:10.540" Title="Why is &quot;dragging it in&quot; considered bad in small aircraft, but fine in larger aircraft?" Tags="&lt;approach&gt;&lt;fixed-wing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1260" PostTypeId="2" ParentId="1246" CreationDate="2014-01-23T09:32:43.847" Score="1" Body="&lt;p&gt;You may take a look at &lt;a href=&quot;http://www.openaip.net&quot; rel=&quot;nofollow&quot;&gt;openAIP&lt;/a&gt;. It contains nearly up-to-date airspace and airport information besides other aviation topics. Airspace data is available for download as .aip file. This is actually a very simple XML file that can easily be used in any application.&lt;/p&gt;&#xA;" OwnerUserId="692" LastActivityDate="2014-01-23T09:32:43.847" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1261" PostTypeId="2" ParentId="1258" CreationDate="2014-01-23T09:33:14.897" Score="13" Body="&lt;p&gt;For the FAA, a &quot;complex aeroplane&quot; must have:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A retractable gear (not necessary for a seaplane);&lt;/li&gt;&#xA;&lt;li&gt;In-flight adjustable flaps; and&lt;/li&gt;&#xA;&lt;li&gt;A controllable pitch propeller.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The FAA's definition is given in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=257acc4699ee7253af775fc7e9492e51&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.1.1.1&quot;&gt;14 CFR 61.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Complex airplane&lt;/em&gt; means an airplane that has a retractable landing&#xA;  gear, flaps, and a controllable pitch propeller, including airplanes&#xA;  equipped with an engine control system consisting of a digital&#xA;  computer and associated accessories for controlling the engine and&#xA;  propeller, such as a full authority digital engine control; or, in the&#xA;  case of a seaplane, flaps and a controllable pitch propeller,&#xA;  including seaplanes equipped with an engine control system consisting&#xA;  of a digital computer and associated accessories for controlling the&#xA;  engine and propeller, such as a full authority digital engine control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, the EASA has a different definition of a &quot;complex motor-powered aircraft&quot; that is an airplane, which is considerably more &quot;complex&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an aeroplane:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;with a maximum certificated take-off mass exceeding 5 700 kg, or&lt;/li&gt;&#xA;  &lt;li&gt;certificated for a maximum passenger seating configuration of more than nineteen, or&lt;/li&gt;&#xA;  &lt;li&gt;certificated for operation with a minimum crew of at least two pilots, or&lt;/li&gt;&#xA;  &lt;li&gt;equipped with (a) turbojet engine(s) or more than one turboprop engine&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that 5700kg is about 12567 pounds.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-23T09:47:21.070" LastActivityDate="2014-01-23T09:47:21.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1262" PostTypeId="1" AcceptedAnswerId="1274" CreationDate="2014-01-23T10:15:59.543" Score="11" ViewCount="12700" Body="&lt;p&gt;Both landings are done when an airplane's nose is not in inline with the runway. How are these two different? when should one technique be preferred over other?&lt;/p&gt;&#xA;" OwnerUserId="689" LastEditorUserId="689" LastEditDate="2014-01-23T16:07:43.190" LastActivityDate="2016-10-27T19:39:21.353" Title="What is the difference between a crabbed and de-crab landing?" Tags="&lt;landing&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1263" PostTypeId="1" AcceptedAnswerId="1267" CreationDate="2014-01-23T11:52:23.867" Score="7" ViewCount="3742" Body="&lt;p&gt;As far as my knowledge goes: There is a 250 kt speed limit under the altitude of 10.000 feet. &lt;a href=&quot;http://puu.sh/6v6zM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;This screenshot&lt;/strong&gt;&lt;/a&gt; seem to show an aircraft below 10.000 feet and traveling at 285 kts at the time i captured the screenshot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think this aircraft posed any threats to other aviation traffic as there is no other traffic in the airspace. I was just curious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly after: I see &lt;a href=&quot;http://puu.sh/6v73q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;this&lt;/strong&gt;&lt;/a&gt; aircraft taking off from the same airport. Doing the same thing as the first plane.&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="62" LastEditDate="2014-01-23T14:41:47.613" LastActivityDate="2014-01-23T14:41:47.613" Title="Did this aircraft illegally exceed 250kts below 10,000ft?" Tags="&lt;easa-regulations&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1265" PostTypeId="1" AcceptedAnswerId="1308" CreationDate="2014-01-23T12:28:56.917" Score="10" ViewCount="6515" Body="&lt;p&gt;I often fly the PMDG 737-800 (with winglets) in my home simulator and most of the time, I find it hard to slow the aircraft down for landing when I descend. Most of the time, I need to deploy the speedbrakes to keep descending without increasing speed. I usually start my descent earlier than the marked top of descent point to make the flight a little smoother. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I was wondering if this is a bug or if the real aircraft actually behaves like this. I have wondered about this for some time. I can only dream about becoming a pilot and find out myself cause of my bad eyesight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://www.youtube.com/watch?v=8BGL5lH-VXY&quot;&gt;video on YouTube&lt;/a&gt; of me landing the 737 where I had to deploy speedbrakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this video is getting a little outdated: I can no longer recall exactly the payload or weight of this aircraft. But I normally fly with a heavy payload.&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="97" LastEditDate="2015-03-25T03:02:45.710" LastActivityDate="2020-12-11T17:02:19.777" Title="Is the descent performance of the PMDG 737-800 accurate?" Tags="&lt;boeing&gt;&lt;boeing-737&gt;&lt;flight-simulator&gt;&lt;descent&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1267" PostTypeId="2" ParentId="1263" CreationDate="2014-01-23T14:07:14.540" Score="18" Body="&lt;p&gt;First of all, this aircraft was flying in Europe, not in FAA land. In Europe there is no general limitation to 250 knots below 10000 ft. There is no EASA airspace restrictions, every country has their own set of rules. There are airspaces that have speed restrictions below 10000 ft, others don't and sometimes aircraft are allowed to go faster than 250 knots with ATC permission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, the 250 knots is an &lt;strong&gt;indicated airspeed&lt;/strong&gt; limitation. At 10000 ft, 250 KIAS (Knots Indicated Air Speed) will be approximately 289 KTAS (Knots True Air Speed). And then there is the additional effect of wind. With a strong tailwind you can exceed 350 knots ground speed while still flying below 250 KIAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, the data in the image you linked is provided by ADS-B. ADS-B can transmit either ground speed or air speed. Under the European ADS-B mandate, aircraft must transmit ground speed, not air speed. But since this mandate will not affect this particular aircraft until December 7, 2017 it might very well be transmitting True Air Speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that ADS-B data is not purely derived from GPS. The Mode S transponder which provides the ADS-B out functionality on this aircraft is attached to various data channels and is getting Indicated Airspeed, barometric vertical rate. In fact ADS-B vertical rate is preferably from a barometric source.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-01-23T14:39:47.767" LastActivityDate="2014-01-23T14:39:47.767" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1268" PostTypeId="2" ParentId="1255" CreationDate="2014-01-23T14:29:36.690" Score="2" Body="&lt;p&gt;Well.. There's not a real easy answer to this question.  Starting a career in aviation is no small undertaking.  Large aviation universities like Embry-Riddle really are a good as they say, but the focus is more on getting a degree along side your flying.  Most airlines require a 4 year degree, but they don't care in what field, they just want to know that you have a good foundation and the commitment to complete your higher education.  That said, if you already have a degree, then you might want to shop around for a place that can focus more on flying and less on the classroom.  If you don't have a degree, then you could consider a large Aviation University, but its not cheap, and it might be until retirement to reap the dividends.  Also know, that smaller flight schools run professional pilot programs and can give a more focused study path.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fair warning, just to get a private,instrument,commercial,multi-engine,ATP certificates will take at least a year if you're &lt;em&gt;highly&lt;/em&gt; motivated, but probably longer. Add school, if needed, and you're at 3-4 years before you can even enter the workforce. Then, after recent legislation, the time required to be a co-pilot with an airline has soared, forcing pilot's to find hours elsewhere.  Generally as a flight instructor which could take another year or three to accumulate enough time to get hired by an airline. Finally after you get planted in the right seat of that airliner, it takes another 3 or 4 years of low seniority grunt work to break 30k in pay. Mandatory retirement is now 65. So now after 9-12 years, your finally an airline pilot, but not much time till retirement.  If you want to fly, and have a desire for aviation, then you should have no problem, you just won't get rich.&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-01-23T14:29:36.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1269" PostTypeId="2" ParentId="1259" CreationDate="2014-01-23T14:33:37.353" Score="21" Body="&lt;p&gt;This is less of a &quot;big -vs- small&quot; question, and more of a &quot;single-engine -vs- multi-engine&quot; question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to answer your question with another question: What would happen if an engine were to fail during the approach in each case? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a single-engine aircraft you want to always be in a position to land if the engine fails, so you don't want to get too far from the runway, while in a multi-engine aircraft you can continue the approach if an engine fails.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You want to be careful not to take this concept too far though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See:  &lt;a href=&quot;https://aviation.stackexchange.com/questions/871/short-approach-vs-normal&quot;&gt;Short approach vs Normal&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, in jet aircraft the power needs to be kept relatively high so that additional power is available quickly if needed since the engines take awhile to accelerate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See:  &lt;a href=&quot;https://aviation.stackexchange.com/questions/1043/why-do-turbine-engines-take-so-long-to-spool-up&quot;&gt;Why do turbine engines take so long to spool up?&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Partially because of this, the idea of a &lt;em&gt;stabilized approach&lt;/em&gt; was widely incorporated.  This requires that the aircraft is in a stable, continuous rate descent to the runway and that the approach be abandoned if not within required parameters at a specified minimum altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A secondary reason is that &quot;larger&quot; aircraft are commonly flying instrument approaches to help transition from the enroute/terminal phase of flight to the runway.  These standard procedures are designed for use in instrument conditions and allow plenty of time to safely configure for a stabilized landing.  Even in visual conditions, they are commonly used when there is a lot of traffic to &quot;put everybody in line&quot;.  Even a small single-engine airplane will probably be further from the runway than they like at big airports, just because of the amount of other traffic.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-01-23T15:29:15.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1270" PostTypeId="2" ParentId="1262" CreationDate="2014-01-23T15:02:09.327" Score="5" Body="&lt;p&gt;Wikipedia's &lt;a href=&quot;http://en.wikipedia.org/wiki/Crosswind_landing#Techniques&quot;&gt;definitions&lt;/a&gt; are a bit unclear but it seems to say that de-crabbing is where you straighten the aircraft in the air just &lt;em&gt;before&lt;/em&gt; touchdown; crabbing is where you straighten on the runway &lt;em&gt;after&lt;/em&gt; touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;De-crabbing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Just before the flare, opposite rudder (downwind rudder) is applied&#xA;  to eliminate the crab&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Crabbing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;upon touchdown the airplane tracks towards the upwind edge of the&#xA;  runway while de-crabbing to align with the runway. Immediate upwind&#xA;  aileron is needed to ensure the wings remain level while rudder is&#xA;  needed to track center line. The greater the amount of crab at&#xA;  touchdown, the larger the lateral deviation from the point of&#xA;  touchdown.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Personally I find these definitions odd: in my limited experience in light aircraft, a &quot;crabbing&quot; approach is what Wikipedia calls &quot;de-crabbing&quot;, and &quot;de-crabbing&quot; is the action of straightening the aircraft in the air before touchdown. I have no idea why a pilot would prefer to land the aircraft at an angle to the runway and then correct on the ground. But perhaps this is normal practice in larger aircraft; I have no idea about that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-01-23T15:02:09.327" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1271" PostTypeId="1" AcceptedAnswerId="1290" CreationDate="2014-01-23T15:32:14.917" Score="15" ViewCount="14619" Body="&lt;p&gt;Most (all?) airlines require the use of a &lt;em&gt;stabilized approach&lt;/em&gt;, and it is constantly referred to as a safer way to land an airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the criteria for an approach to be considered stabilized?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes it safer than a &quot;normal&quot; (unstabilized?) approach?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-23T16:49:44.477" LastActivityDate="2020-04-11T13:30:26.963" Title="What is a stabilized approach?" Tags="&lt;landing&gt;&lt;approach&gt;&lt;visual-approaches&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1272" PostTypeId="2" ParentId="1259" CreationDate="2014-01-23T16:40:44.300" Score="26" Body="&lt;p&gt;For the GA fleet, there is some historical precedent operating here.  Years ago, engines were much less reliable than they are today.  Dragging it in generally means that you cannot glide it in if you have a complete power failure.  This translates to saying in the event of an engine failure, you are landing off airport with limited selection of landing sites (your altitude is low as you are now below pattern altitude).  So if you are flying behind an old Curtis OX-5 in your Jenny, a gliding approach to landing was recommended back in the day.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines are much more reliable today.  After an analysis of landing accidents, the FAA determined that a stabilized approach to landing is less likely to result in an accident, and they changed their guidance accordingly. Stabilized approaches are partial power-on landings.  Some old timers and some old time CFIs reject the FAA's statistical analysis and still teach/fly glide-it-in landings.  Properly executed, both approaches to landing are safe.  It is just that the FAA thinks that stabilized approaches are safer given engines commonly in use today.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also true that virtually all airlines require stabilized approaches in their operating specs, and that a go around is mandatory if the approach is not stabilized.  With this in mind, flight schools that aspire to send their graduates to the majors will all teach stabilized approaches.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-23T17:21:18.677" LastActivityDate="2014-01-23T17:21:18.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1273" PostTypeId="2" ParentId="1265" CreationDate="2014-01-23T16:56:06.317" Score="1" Body="&lt;p&gt;I have not flown the 737, but I can tell you that jets &lt;em&gt;in general&lt;/em&gt; have a relatively low amount of drag (they are very &quot;clean&quot;).  This makes them hard to slow down and they build up speed easily and quickly.  The 737-800 is a Next Generation 737, and has the updated wing that includes (among other enhancements) winglets, so this problem would be even more prevalent than on the classic 737's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slowing down and going down at the same time is very hard to do in airplanes like this, and use of spoilers is almost always required when the airplane is in a clean configuration if you need to do both.  Descent planning is an important part of flight in such aircraft.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-23T16:56:06.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1274" PostTypeId="2" ParentId="1262" CreationDate="2014-01-23T17:01:05.970" Score="16" Body="&lt;p&gt;Consider where the center of gravity is in relation to the main wheels. If you are in a tail dragger, you definitely would prefer to de-crab (never heard that term before now) before touching down. If you touched down while crabbed, you'd have a moment created by the center of gravity around the main gear to ground loop the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a tricycle gear airplane, that same moment would work to straighten the airplane since the center of gravity is forward of the main gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a crosswind from the right, for example, when you apply left rudder to align the aircraft with the runway, the right wing will want to come up (you just gave it a little extra speed), so you will want to use right aileron to at least counter that as you certainly don't want the crosswind component to get 'under' the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both 747 operators I flew for recommended touching down in the crab. Personally I didn't like that and used a combination approach in a heavy crosswind, take out some of the crab but not all. Also, while they did caution against lowering the upwind wing, I always lowered the wing a little. I once figured out how much the wing would have to be lowered before ground contact, and it was quite substantial, more than I would ever think of using. Also, as I remember, It would not be the wingtip or an outboard engine pod that would make first contact, but rather the outboard corner of the outboard wing flap when set to flaps 30.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, when your touch down speed is 140 knots, for example, you'll have to crab much less for a given crosswind component than if your touchdown speed is 70 knots. Cosine or tangent of the angle, I forget which.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-10-27T19:12:17.410" LastActivityDate="2016-10-27T19:12:17.410" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1275" PostTypeId="2" ParentId="1257" CreationDate="2014-01-23T17:03:11.533" Score="18" Body="&lt;p&gt;Whether to use a &lt;em&gt;static&lt;/em&gt; or a &lt;em&gt;rolling&lt;/em&gt; takeoff is usually at the discretion of the captain as long as performance is not an issue and ATC doesn't need you to wait on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons to do a static takeoff include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less runway is required&lt;/li&gt;&#xA;&lt;li&gt;Better obstacle clearance (mainly because of the earlier liftoff)&lt;/li&gt;&#xA;&lt;li&gt;Takeoff engine power can be confirmed prior to brake release&lt;/li&gt;&#xA;&lt;li&gt;ATC may require an aircraft to wait on the runway due to wake turbulence separation requirements&lt;/li&gt;&#xA;&lt;li&gt;The aircraft manufacturer may not allow a rolling takeoff&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Reasons to do a rolling takeoff:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is sufficient runway available&lt;/li&gt;&#xA;&lt;li&gt;Obstacles are not an issue&lt;/li&gt;&#xA;&lt;li&gt;Takeoff engine power can be set relatively quickly and an abort can still be made at a low speed&lt;/li&gt;&#xA;&lt;li&gt;They take less time to perform, and at busy airports this can mean getting another airplane or two out/in per hour&lt;/li&gt;&#xA;&lt;li&gt;They offer more passenger comfort because of the smoother acceleration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Not all airplanes provide performance information for rolling take offs. In this case, a commonly used technique is to ensure that takeoff power is set by a certain point on the runway and adding that distance to your calculated takeoff roll for planning purposes.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="6" LastEditDate="2014-01-23T19:48:05.963" LastActivityDate="2014-01-23T19:48:05.963" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1276" PostTypeId="1" AcceptedAnswerId="1277" CreationDate="2014-01-23T17:06:50.610" Score="13" ViewCount="2546" Body="&lt;p&gt;The FAA offers instrument approach procedures on their website free of charge (&lt;a href=&quot;http://aeronav.faa.gov/index.asp?xml=aeronav/applications/d_tpp&quot;&gt;FAA Charts&lt;/a&gt;).  Is there a similar site provided by EASA or the EU?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-04T17:49:56.357" LastActivityDate="2019-02-03T04:11:36.857" Title="Is there an online source for European Instrument Approach Procedures?" Tags="&lt;iaps&gt;&lt;aeronautical-charts&gt;&lt;easa&gt;&lt;eu&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1277" PostTypeId="2" ParentId="1276" CreationDate="2014-01-23T17:10:13.373" Score="13" Body="&lt;p&gt;Eurocontrol has an online repository of &lt;a href=&quot;http://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&quot; rel=&quot;noreferrer&quot;&gt;European Aeronatical Information Services&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll need to register, but the basic service is free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By default, the application is JAVA applet based, which works not in the best way. After logging on, you can change the default behaviour to HTML based, which makes it more user friendly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GL40C.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then clicking &quot;Enter Application&quot; will bring to the next level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here you'll find several reporting options, but what you are interested in is located under &quot;PAMS Light [AIP]&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iuMuw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Select the country you are interested in, &quot;Charts&quot; for AIP type and &quot;AD&quot; for Aerodrome and there you have the charts. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-01-23T17:43:24.307" LastActivityDate="2014-01-23T17:43:24.307" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1279" PostTypeId="2" ParentId="1271" CreationDate="2014-01-23T17:18:20.860" Score="6" Body="&lt;p&gt;The airlines I flew for considered a stabilized approach to be a constant airspeed and thus constant rate of descent from the outer marker to the flare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was touted as a safer approach because it removed the variable of a changing airspeed and thus a changing rate of descent. Controllers, I think, also more or less depend on it or for spacing when things are busy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, however, there's no traffic, I observed that whether American pilots used a stabilized approach was more often than not a matter of their experience. Personally, I never used a stabilized approach when I didn't have to. They waste time and fuel, and they're not as much fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note my qualification of American pilots. We had the advantage, at least back in the days of a strong general aviation population, of having a lot of experience working up through different conditions and different aircraft types. Japanese and Korean pilots and others who had gone through ab initio training had never been taught anything but stabilized approaches and thus would always fly such.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-01-23T18:51:54.017" LastActivityDate="2014-01-23T18:51:54.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1281" PostTypeId="2" ParentId="1265" CreationDate="2014-01-23T19:01:01.423" Score="5" Body="&lt;p&gt;Until someone with more authority steps in...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a friend who flies 737's and he has mentioned several times how well they glide and how difficult they are to slow down. He tries really hard to not to use the speedbrakes because &quot;they just shake the plane&quot; making an uncomfortable experience for the passengers. They simply manage this &quot;problem&quot; (actually a really good thing in terms of fuel burn) by planning the descent properly, and always starting down early enough to not require spoilers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't speak as to the accuracy of PMDG, but I would guess the performance you're seeing is at least roughly similar to real world, and it's your descent planning which needs adjusting. What surprises me is that the FMS wouldn't automatically select a reasonable top of descent, but perhaps there is a difference between how you are flying the descent and how the FMS expected it to be flown.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2014-01-23T19:01:01.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1282" PostTypeId="1" AcceptedAnswerId="1283" CreationDate="2014-01-23T19:57:38.187" Score="33" ViewCount="11831" Body="&lt;p&gt;On the &lt;a href=&quot;http://skyvector.com/?ll=36.186880306392254,-95.88262939757304&amp;amp;chart=301&amp;amp;zoom=1&quot; rel=&quot;noreferrer&quot;&gt;Tulsa, Oklahoma VFR sectional&lt;/a&gt; the top of the outer Class C ring says &quot;OBJECTIONABLE&quot;. Does this indicate some information on the chart is in dispute? I don't see anything in the VFR chart legend or side panels about the meaning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/q6gna.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="167" LastEditDate="2014-05-14T01:57:54.677" LastActivityDate="2014-12-27T18:00:43.130" Title="What does &quot;OBJECTIONABLE&quot; indicate on a VFR chart?" Tags="&lt;airspace&gt;&lt;aeronautical-charts&gt;&lt;symbology&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1283" PostTypeId="2" ParentId="1282" CreationDate="2014-01-23T20:37:59.737" Score="20" Body="&lt;p&gt;It means that the airspace around the airport is still under review after a proposed change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This article explains it in more detail: &lt;a href=&quot;http://expertaviator.com/2012/07/31/what-is-an-objectionable-airport/&quot;&gt;http://expertaviator.com/2012/07/31/what-is-an-objectionable-airport/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And here's the official text: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=dcd99a685fc7b1dcde1663cbc9b6884c&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:3.0.1.3.27&amp;amp;idno=14&quot;&gt;Part 157&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§157.7   FAA determinations. (a) The FAA will conduct an aeronautical&#xA;  study of an airport proposal and, after consultations with interested&#xA;  persons, as appropriate, issue a determination to the proponent and&#xA;  advise those concerned of the FAA determination. The FAA will consider&#xA;  matters such as the effects the proposed action would have on existing&#xA;  or contemplated traffic patterns of neighboring airports; the effects&#xA;  the proposed action would have on the existing airspace structure and&#xA;  projected programs of the FAA; and the effects that existing or&#xA;  proposed manmade objects (on file with the FAA) and natural objects&#xA;  within the affected area would have on the airport proposal. While&#xA;  determinations consider the effects of the proposed action on the safe&#xA;  and efficient use of airspace by aircraft and the safety of persons&#xA;  and property on the ground, the determinations are only advisory.&#xA;  Except for an objectionable determination, each determination will&#xA;  contain a determination-void date to facilitate efficient planning of&#xA;  the use of the navigable airspace. A determination does not relieve&#xA;  the proponent of responsibility for compliance with any local law,&#xA;  ordinance or regulation, or state or other Federal regulation.&#xA;  Aeronautical studies and determinations will not consider&#xA;  environmental or land use compatibility impacts.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) An airport determination issued under this part will be one of the&#xA;  following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) No objection.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Conditional. A conditional determination will identify the&#xA;  objectionable aspects of a project or action and specify the&#xA;  conditions which must be met and sustained to preclude an&#xA;  objectionable determination.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) &lt;strong&gt;Objectionable. An objectionable determination will specify the&#xA;  FAA's reasons for issuing such a determination&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Determination void date. All work or action for which notice is&#xA;  required by this sub-part must be completed by the determination void&#xA;  date. Unless otherwise extended, revised, or terminated, an FAA&#xA;  determination becomes invalid on the day specified as the&#xA;  determination void date. Interested persons may, at least 15 days in&#xA;  advance of the determination void date, petition the FAA official who&#xA;  issued the determination to:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Revise the determination based on new facts that change the basis&#xA;  on which it was made; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Extend the determination void date. Determinations will be&#xA;  furnished to the proponent, aviation officials of the state concerned,&#xA;  and, when appropriate, local political bodies and other interested&#xA;  persons.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-23T21:05:46.803" LastActivityDate="2014-01-23T21:05:46.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1284" PostTypeId="2" ParentId="1282" CreationDate="2014-01-23T20:39:24.363" Score="13" Body="&lt;p&gt;According to the FAA Aeronautical Navigation Products &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/faq/index.cfm?print=go#q3d&quot;&gt;FAQ&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What does &quot;OBJECTIONABLE&quot; stand for on VFR Charts?&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;OBJECTIONABLE&quot; indicates an airspace determination per FAA Joint&#xA;  Order 7400.2J Section 4, Airport Charting and Publication of Airport&#xA;  Data, issued 9 FEB 2012. When you see this indication on a chart be&#xA;  sure to refer to the applicable Airport/Facility Directory for more&#xA;  information. FAA Regional Airports Offices are responsible for&#xA;  airspace determinations. Address any challenges to objectionable&#xA;  airspace determinations to your regional airports office.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/AIR.pdf&quot;&gt;&lt;strong&gt;FAA Joint Order 7400.2J&lt;/strong&gt;&lt;/a&gt; Section 4 refers to Airport Airspace Analysis and says (emphasis added by me):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;10−1−1. PURPOSE&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. This part provides guidelines, procedures, and standards that&#xA;  supplement those contained in 14 CFR part 157, Notice of Construction,&#xA;  Alteration, Activation, and Deactivation of Airports.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. These guidelines, procedures, and standards &lt;strong&gt;&lt;em&gt;must be used in&#xA;  determining the effect construction, alteration, activation, or&#xA;  deactivation of an airport will have on the safe and efficient use of&#xA;  the navigable airspace by aircraft&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;10−4−1. POLICY&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. All landing facilities which have received airspace determinations&#xA;  or those not analyzed, must be properly documented and processed in&#xA;  accordance with procedures contained in FAAO 5010.4, Airport Safety&#xA;  Data Program.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. &lt;strong&gt;&lt;em&gt;Landing facilities that have received objectionable airspace&#xA;  determinations must be published in the NFDD as “objectionable.”&lt;/em&gt;&lt;/strong&gt; They&#xA;  must be depicted on VFR aeronautical charts only and without&#xA;  identifying text other than to designate objectionable status. They&#xA;  must not be published in the Airport/Facility Directory (A/FD).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-23T21:05:57.553" LastActivityDate="2014-01-23T21:05:57.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1285" PostTypeId="1" AcceptedAnswerId="1286" CreationDate="2014-01-23T20:56:31.030" Score="19" ViewCount="3663" Body="&lt;p&gt;Is it just my imagination, or is it a fact that many large airliners actually touch down &quot;crabbed&quot; on difficult crosswind landings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's what I mean in &lt;a href=&quot;https://www.youtube.com/watch?v=OtnL4KYVtDE#t=66&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;, or as shown in this picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2ncBn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the main landing gear specifically designed to allow this? Is it recommended or discouraged by the manufacturer?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="65" LastEditDate="2015-02-11T21:00:15.503" LastActivityDate="2016-07-04T17:29:04.167" Title="Is the main landing gear of a large airplane designed for sideways (crabbed) touchdowns?" Tags="&lt;landing&gt;&lt;crosswind&gt;&lt;pilot-technique&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1286" PostTypeId="2" ParentId="1285" CreationDate="2014-01-23T22:10:41.483" Score="19" Body="&lt;p&gt;The landing gear is indeed designed to cope with crabbed crosswind landings.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recommendation is to avoid crab on landing however in severe crosswind conditions it is sometimes impossible to decrab completely without introducing excessive bank. Therefore some residual crab has to be allowed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus recommends &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-LAND-SEQ05.pdf&quot;&gt;less then 5 degrees&lt;/a&gt; of residual crab on landing, but aircraft are designed to cope with more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An exceptional design is found in the B-52, where the main landing gear can rotated to be aligned with the direction of travel to deal with extreme crab angles. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-23T22:10:41.483" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1287" PostTypeId="1" AcceptedAnswerId="1289" CreationDate="2014-01-23T22:19:30.000" Score="16" ViewCount="1746" Body="&lt;p&gt;At a controlled airport, the tower advises large flocks of small birds at the approach end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm in a small trainer aircraft like a Cherokee or Cessna 172. Should I request to land the other way (Rwy 9 vs 27), proceed as normal but just expect them to only be a distraction?  What are the best options here?&lt;/p&gt;&#xA;" OwnerUserId="526" LastEditorUserId="3386" LastEditDate="2016-04-24T17:20:46.663" LastActivityDate="2016-04-25T01:27:03.410" Title="What is the best strategy for landing when a flock of birds is on the runway?" Tags="&lt;landing&gt;&lt;birds&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1288" PostTypeId="2" ParentId="1287" CreationDate="2014-01-23T22:23:11.060" Score="2" Body="&lt;p&gt;The best option is to go around.  Maybe the noise of you passing overhead will scare them into the air and they will land elsewhere.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-23T22:23:11.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1289" PostTypeId="2" ParentId="1287" CreationDate="2014-01-23T23:15:31.160" Score="24" Body="&lt;p&gt;I think the answer depends on what the birds are doing, but all options are basically &quot;at the pilot's risk&quot; - the tower is just advising you there are some birds hanging around the airport, but nobody can say how they're going to react to you trying to land there too.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the flock is airborne and flying across the final (completely neglecting to coordinate their movements with tower, as birds are wont to do) you can request an extended downwind until they've moved on.&lt;br&gt;&#xA;This has happened to me twice, and in my experience birds tend to be far less interested in airports than pilots. They're usually gone in a minute or two.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If they're sitting &lt;em&gt;on&lt;/em&gt; the runway somewhere you can try a low pass over the field to scare them off, but my preference would be to ask the tower/unicom operator if they can chase them away for me with a ground vehicle (so I'm not near the flock in case they decide to disperse &quot;upward&quot; instead of &quot;outward&quot;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If they're just pecking around in the grass near the approach end of the runway looking for lunch &lt;a href=&quot;https://aviation.stackexchange.com/a/1288/64&quot;&gt;Skip Miller&lt;/a&gt; &amp;amp; &lt;a href=&quot;https://aviation.stackexchange.com/questions/1287/flock-of-birds-at-approach-end-of-runway#comment2019_1287&quot;&gt;p1l0t&lt;/a&gt; have the right idea with a go-around or low approach/overflight to scare them off.&lt;br&gt;&#xA;(This is part of why a low pass over an unattended uncontrolled field is often advisable -- you'll hopefully scare off any critters on the runway that you wouldn't want there when you actually land.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If they're &quot;airport birds&quot; you might want to just land.&lt;br&gt;&#xA;Some of the airports by me have resident flocks of birds that I'm convinced just sit there and rate people's landings - I swear I saw the same birds every day shooting touch-and-gos.&lt;br&gt;&#xA;These are the kind of birds that aren't going to scatter when you do a low pass unless you hit them with your landing gear, so just be aware of where they are (in case they lose their minds and try to commit suicide by propeller) but they probably won't bother you.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I don't think I'd ask for a downwind landing because of birds (unless we're talking geese or hawks or something), but if it's a calm-wind day, the pattern is empty, and you're more comfortable with that idea go ahead and ask. The worst the tower can do is say &quot;unable&quot;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-01-23T23:15:31.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1290" PostTypeId="2" ParentId="1271" CreationDate="2014-01-23T23:46:54.750" Score="13" Body="&lt;p&gt;When you look at FAA publications &lt;a href=&quot;http://www.faa.gov/news/safety_briefing/2013/media/se_topic_june_2013.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the criteria for a &quot;stabilized approach&quot;&lt;/a&gt; is pretty simple:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A stabilized approach is one in which the pilot establishes and maintains a constant angle glidepath towards a predetermined point on the landing runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;When pilots talk about stabilized approaches we generally mean a little more than that though - for example &lt;a href=&quot;http://www.skybrary.aero/index.php/Stabilised_Approach&quot; rel=&quot;nofollow noreferrer&quot;&gt;the SKYbrary description of a stabilized approach&lt;/a&gt;, &lt;a href=&quot;http://flightsafety.org/files/alar_bn7-1stablizedappr.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Flight Safety Foundation&lt;/a&gt;, and &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-APPR-SEQ01.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus&lt;/a&gt; all include more than just the constant-angle glide path in their recommendations for what makes an approach &quot;stabilized&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Criteria that are commonly included in a &quot;stabilized approach&quot; are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maintaining a constant-angle glidepath toward a predetermined aiming point on the runway.&lt;/li&gt;&#xA;&lt;li&gt;Maintaining a specified descent rate&lt;/li&gt;&#xA;&lt;li&gt;Maintaining a specified airspeed (V&lt;sub&gt;app&lt;/sub&gt;)&lt;br&gt;&#xA;(Generally being &lt;em&gt;slightly&lt;/em&gt; above V&lt;sub&gt;app&lt;/sub&gt; is OK, but below is unacceptable.)&lt;/li&gt;&#xA;&lt;li&gt;Having the aircraft configured for landing (gear, flaps, etc.)&lt;/li&gt;&#xA;&lt;li&gt;All required checklists completed&lt;/li&gt;&#xA;&lt;li&gt;The approach can be maintained with only &quot;small corrections&quot; to pitch, heading, or power.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An approach is &quot;stabilized&quot; if all the required criteria are met by a specific altitude (Airbus calls them &quot;Stabilization Heights&quot;, and recommends 500 feet for approaches in VMC, and 1000 feet for approaches in IMC).&lt;br&gt;&#xA;If the approach is not stabilized by the appropriate stabilization height (or conditions cause the approach to become &quot;destabilized&quot; - a sudden change in winds for example) the approach is abandoned (a &quot;go-around&quot;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So what makes stabilized approaches safer?&lt;/strong&gt;&lt;br&gt;&#xA;The theory is that a stabilized approach reduces the pilot's workload as they're getting closer to the ground: If the aircraft is configured for landing and all the checklists have been completed all the pilot has to do is gently nudge the controls to keep the plane going where they want it, and they can concentrate all of their attention on a nice, safe, (hopefully) smooth landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are stabilized approaches always safer?&lt;/strong&gt;&lt;br&gt;&#xA;From a workload perspective, yes. It's hard to argue with &quot;The pilot has less work to do&quot;.&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1259/why-is-dragging-it-in-considered-bad-in-small-aircraft-but-fine-in-larger-air&quot;&gt;From a &quot;What if my one-and-only engine dies?&quot; perspective, maybe not.&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stabilized approaches generally require partial power to be maintained throughout the approach, and although the engines in modern single-engine piston/jet aircraft have a pretty good track record of reliability there are good arguments for &quot;non-stabilized&quot; approaches (or approaches that are effectively &quot;stabilized&quot; at idle power) in single-engine aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you're &lt;em&gt;not&lt;/em&gt; flying a &quot;stabilized approach&quot; the way the airline folks define it you're well-served by incorporating some of the elements though - going around if your checklists aren't completed by a certain altitude, abandoning the approach if you have to manhandle the controls to try to keep things together, etc.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-01-23T23:46:54.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1291" PostTypeId="5" CreationDate="2014-01-24T03:36:48.370" Score="0" Body="" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-24T03:36:48.370" LastActivityDate="2014-01-24T03:36:48.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1292" PostTypeId="4" CreationDate="2014-01-24T03:36:48.370" Score="0" Body="Questions related to aerodynamic spins (intentional or otherwise), including spin entry and recovery techniques." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-01-24T03:36:48.370" LastActivityDate="2014-01-24T03:36:48.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1293" PostTypeId="1" AcceptedAnswerId="1300" CreationDate="2014-01-24T05:34:00.237" Score="6" ViewCount="4324" Body="&lt;p&gt;Are pilots allowed to perform FMS database updates under part 135?  If so, do they need formal training entered in their pilot records before they are allowed to do it? &lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="62" LastEditDate="2014-01-24T20:07:46.353" LastActivityDate="2014-01-24T21:06:59.847" Title="May pilots perform FMS database updates under Part 135?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;far-135&gt;&lt;fms&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1294" PostTypeId="1" AcceptedAnswerId="1299" CreationDate="2014-01-24T06:25:01.083" Score="8" ViewCount="8064" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/1263/did-this-aircraft-illegally-exceed-250kts-below-10-000ft&quot;&gt;Did this aircraft illegally exceed 250kts below 10,000ft?&lt;/a&gt; it was mentioned that unlike here in the US, EASA does not have a 250 kt. speed limit below 10,000 ft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So does this mean that are we allowed to go as fast as we want?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://fun.datang.net/pic/indexp568.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mQaid.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mach 8? ;-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the maximum indicated airspeed specified by EASA when operating in the European Union?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2021-05-10T21:30:31.960" Title="What is the speed limit in European airspace?" Tags="&lt;easa-regulations&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1295" PostTypeId="1" AcceptedAnswerId="1297" CreationDate="2014-01-24T06:28:58.153" Score="3" ViewCount="3644" Body="&lt;p&gt;The &lt;a href=&quot;http://aeronav.faa.gov/index.asp?xml=aeronav/applications/d_tpp&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA&lt;/a&gt; offers instrument approach procedures on their website free of charge, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1276/is-there-an-online-source-for-european-instrument-approach-procedures&quot;&gt;EASA&lt;/a&gt; does too.  Does Canada have them online for us to use?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-01-24T12:56:53.517" Title="Is there an online source for Canadian Instrument Approach Procedures?" Tags="&lt;iaps&gt;&lt;aeronautical-charts&gt;&lt;transport-canada&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1296" PostTypeId="2" ParentId="1293" CreationDate="2014-01-24T07:58:14.377" Score="4" Body="&lt;p&gt;I assume that by updating you mean loading a pre-compiled database into the FMS, replacing the old one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RNAV database inside the FMS should be updated according to the 28 day Aeronautical Information Regulation and Control (AIRAC) cycle. Typically this is a maintenance task and the pilot has no play in this. Of course if the pilot also holds the required maintenance certificates, then he can update the database in the appropriate way. However, he is not acting in his capacity of pilot in that case, but wearing his maintenance hat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases the database update is not considered maintenance and can be performed by the pilot. 14 CFR Part 43 covers Maintenance, preventive maintenance, rebuilding and alteration. It contains an interesting section regarding databases; 14 CFR § 43.3(k) specifically addresses database updates.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(k) &lt;strong&gt;&lt;em&gt;Updates of databases in installed avionics meeting the conditions&#xA;  of this paragraph are not considered maintenance&lt;/em&gt;&lt;/strong&gt; and may be performed&#xA;  by pilots provided:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The database upload is:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Initiated from the flight deck;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Performed without disassembling the avionics unit; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Performed without the use of tools and/or special equipment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The pilot must comply with the certificate holder's procedures or&#xA;  the manufacturer's instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The holder of operating certificates must make available written&#xA;  procedures consistent with manufacturer's instructions to the pilot&#xA;  that describe how to:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Perform the database update; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Determine the status of the data upload.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If these conditions are not met, then there is a final escape door which might apply to Part 135 rotorcraft pilots:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=9d7de8e7c84faf84a2822512f76c1002&amp;amp;node=14:1.0.1.3.21.0.363.3&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR § 43.3(h)&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(h) Notwithstanding the provisions of paragraph (g) of this section,&#xA;  the Administrator may approve a certificate holder under Part 135 of&#xA;  this chapter, &lt;strong&gt;&lt;em&gt;operating rotorcraft in a remote area&lt;/em&gt;&lt;/strong&gt;, to allow a pilot&#xA;  to perform specific preventive maintenance items provided—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The items of preventive maintenance are a result of a known or&#xA;  suspected mechanical difficulty or malfunction that occurred en route&#xA;  to or in a remote area;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The pilot has satisfactorily completed an approved training&#xA;  program and is authorized in writing by the certificate holder for&#xA;  each item of preventive maintenance that the pilot is authorized to&#xA;  perform;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) There is no certificated mechanic available to perform preventive&#xA;  maintenance;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) The certificate holder has procedures to evaluate the&#xA;  accomplishment of a preventive maintenance item that requires a&#xA;  decision concerning the airworthiness of the rotorcraft; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) The items of preventive maintenance authorized by this section are&#xA;  those listed in paragraph (c) of appendix A of this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the database update meets the conditions stated in paragraph (k) of  14 CFR § 43.3 it is not considered maintenance and may be performed by the pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When  CFR § 43.3 (k) conditions are not met the pilot cannot perform the update unless the Administrator approves it under 14 CFR § 43.3(h).&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="69" LastEditDate="2014-01-24T21:06:59.847" LastActivityDate="2014-01-24T21:06:59.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1297" PostTypeId="2" ParentId="1295" CreationDate="2014-01-24T11:24:21.300" Score="4" Body="&lt;p&gt;Not officially, no. The official approaches are available in a PDF format to download for 20 CAD for each volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;https://www.fltplan.com/canadianapproachplates.htm&quot; rel=&quot;nofollow&quot;&gt;FltPlan.com&lt;/a&gt; claims to provide free, up-to-date charts:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In cooperation with Nav Canada, FltPlan.com is pleased to announce&#xA;  free Canadian Approach Plates, also know as CAP (Canada Air Pilot).&#xA;  These online charts include all instrument approaches, airport&#xA;  diagrams, SIDs, STARs, and special use approach plates for Canadian&#xA;  Airports. They work similarly to the already available U.S. approach&#xA;  plates.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;CAP is an extension of FltPlan.com's continuously expanding coverage&#xA;  of Canada, Mexico, Latin America and the Caribbean. In May of this&#xA;  year, we expanded our coverage to include the filing of IFR&#xA;  intra-Canada flight plans. The availability of free, online Canadian&#xA;  Approach Plates brings a new level of safety and convenience for&#xA;  pilots in the planning stages of their trip.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though I have not seen anything from Nav Canada stating that this is &quot;in cooperation with Nav Canada&quot;, they do &lt;a href=&quot;http://www.navcanada.ca/EN/products-and-services/Pages/List-Distributors.aspx&quot; rel=&quot;nofollow&quot;&gt;seem to be an authorised distributor&lt;/a&gt; of paper charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note &lt;a href=&quot;https://www.fltplan.com/canadianapproachplates.htm&quot; rel=&quot;nofollow&quot;&gt;FltPlan.com&lt;/a&gt; warns that these charts shall not be printed as a replacement for &quot;proper&quot; paper charts -- I am not sure whether these are deemed to be official or not, but it is rather unlikely.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-24T12:56:53.517" LastActivityDate="2014-01-24T12:56:53.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1298" PostTypeId="2" ParentId="1295" CreationDate="2014-01-24T12:44:23.180" Score="1" Body="&lt;p&gt;There is currently no official source of free Canadian Aeronautical Publications which can be printed for use.&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2014-01-24T12:44:23.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1299" PostTypeId="2" ParentId="1294" CreationDate="2014-01-24T13:00:19.633" Score="9" Body="&lt;p&gt;Airspace regulations do not fall under the authority of EASA. Each country has their own set of rules published under supervision of their own National Aviation Authority in the AIP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The origin of the 250 knots IAS limitation below 10000ft can be found in the ICAO airspace classes definitions. The ICAO airspace definitions include a 250 knots IAS limitation below 10000ft / FL100 in:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Class C: VFR&lt;/li&gt;&#xA;&lt;li&gt;Class D, E, F and G: both VFR and IFR&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That means that in class A and B there is no speed limitation below 10000ft / FL100. In class C, IFR has no speed limitation, but VFR has. In Europe you will find a lot of class A, B and C airspace below 10000ft. In the US, there is no class A airspace below 18000' feet. There is class B and C airspace below 10000ft, but the FAA basically put a blanket speed limitation of 250knots below 10000ft, even inside class B and C airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that ICAO airspace classes are recommendations, countries have the authority to deviate from the ICAO recommendations as long as they publish these deviations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section ENR (En-route) 1.4 of the AIP contains the ATS Airspace Classifications and states includes the deviations from the ICAO airspace definition. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-24T13:00:19.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1300" PostTypeId="2" ParentId="1293" CreationDate="2014-01-24T13:19:47.310" Score="5" Body="&lt;p&gt;Updating a navigation database used to be considered &lt;em&gt;preventative maintenance&lt;/em&gt; and was required to be performed by a mechanic under Part 135.  However, the regulations were changed at the end of 2012 (here is the &lt;a href=&quot;https://www.federalregister.gov/articles/2012/11/29/2012-28845/pilot-loading-of-aeronautical-database-updates#h-36&quot; rel=&quot;nofollow&quot;&gt;final rule&lt;/a&gt;) and it no longer falls under this category so pilots are allowed to update &quot;aeronautical databases&quot; (a new term) if it is &quot;easy&quot; to do (see the regulation quoted below for the exact requirements).  There is no training requirement specified by the regulations, however there may be company specific procedures which require it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.21&amp;amp;idno=14#14:1.0.1.3.21.0.363.3&quot; rel=&quot;nofollow&quot;&gt;14 CFR 43.3&lt;/a&gt; was updated, and now says (in part):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(k) Updates of databases in installed avionics meeting the conditions&#xA;  of this paragraph are not considered maintenance and may be performed&#xA;  by pilots provided:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The database upload is:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Initiated from the flight deck;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Performed without disassembling the avionics unit; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Performed without the use of tools and/or special equipment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The pilot must comply with the certificate holder's procedures or&#xA;  the manufacturer's instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) &lt;strong&gt;The holder of operating certificates must make available written&#xA;  procedures consistent with manufacturer's instructions to the pilot&#xA;  that describe how to:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Perform the database update; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Determine the status of the data upload.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-24T21:01:59.837" LastActivityDate="2014-01-24T21:01:59.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1301" PostTypeId="1" AcceptedAnswerId="1304" CreationDate="2014-01-24T16:36:54.510" Score="9" ViewCount="574" Body="&lt;p&gt;Many airports have parallel runways but only one runway has a PAPI/VASI. If both runways start at the same point and have similar touch-down points, is it safe to use the parallel runway's lights for the approach and landing?&lt;/p&gt;&#xA;" OwnerUserId="81" LastActivityDate="2014-01-24T17:56:26.260" Title="Is it safe to use a parallel runway's PAPI/VASI?" Tags="&lt;runways&gt;&lt;airport-lighting&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1302" PostTypeId="2" ParentId="1301" CreationDate="2014-01-24T17:06:03.620" Score="2" Body="&lt;p&gt;It is considered &quot;safe&quot; for a pilot to use &lt;strong&gt;&lt;em&gt;all&lt;/em&gt;&lt;/strong&gt; available information to safely conduct a flight.  This does not exclude using other references, such as a parallel PAPI as a means to cross-check.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is not &lt;em&gt;legal&lt;/em&gt; to use a parallel PAPI as your primary guidance.   If there were to be an incident, and you were to tell an investigator, &quot;the parallel PAPI indicated that I was on the GS&quot;, he'd think you were a bit nutty, and fault you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If instead, you were able to tell him &quot;I was properly lined up for the Left, and then cross-checked with the PAPI on the Right, which also indicated a stabilized approach on the GS&quot;, he might commend you for creative cross-checking.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-01-24T17:13:04.607" LastActivityDate="2014-01-24T17:13:04.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1303" PostTypeId="2" ParentId="1301" CreationDate="2014-01-24T17:11:30.477" Score="3" Body="&lt;p&gt;Not necessarily.  The PAPI is installed, and the angle is set for the obstacles in the approach path for that specific runway.  There could be obstacles on the parallel that the other PAPI would not give you clearance over because it was never surveyed for that.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-24T17:11:30.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1304" PostTypeId="2" ParentId="1301" CreationDate="2014-01-24T17:50:40.430" Score="6" Body="&lt;p&gt;Per the AIM (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0201.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;2-1-2 - Visual Glideslope Indicators&lt;/a&gt;) &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The visual glide path of the PAPI typically provides safe obstruction clearance within plus or minus 10 degrees of the extended runway centerline and to 4 SM from the runway threshold.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Deviations from that are supposed to be noted in the Airport/Facility Directory, for example if the clearance path is offset from the centerline, or theoretically if you &lt;em&gt;could&lt;/em&gt; use a parallel PAPI...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few miles out you're probably within the 10 degree arc, so the PAPI will be useful, but as you get closer that arc narrows, &lt;a href=&quot;https://aviation.stackexchange.com/a/1303/64&quot;&gt;and as Lnafziger mentioned there might be an obstacle in your way&lt;/a&gt; (like the FAA-Standard 50-foot tree right at the threshold line).&lt;br&gt;&#xA;Also &lt;a href=&quot;https://aviation.stackexchange.com/a/1302/64&quot;&gt;as abelenky pointed out&lt;/a&gt; you're not supposed to be using parallel PAPIs/VASIs for approach guidance - It's a good cross-check, but not a primary reference.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-01-24T17:56:26.260" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1305" PostTypeId="2" ParentId="1255" CreationDate="2014-01-24T17:56:44.007" Score="8" Body="&lt;p&gt;The cost from 0 to ATP can be highly variable.  An easier number to quantify is 0 - Commercial/CFI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the cost of 0 - Comm/CFI can vary, but there are a few accelerated programs that offer this.  One service (I'm not advertising, so I'm not naming them) offers a program that lasts 150 days and costs $65,000* + checkride expenses.  You start with nothing and end up with single/multi commercial, an instrument rating and your CFI/MEI/II along with 100 hours multi-engine time.  This particular program (and others like it probably) hires their instructors from within, so there is a possibility for multi-instruction -- but you won't be making much money for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost of commercial to ATP is harder to nail down because of the possibilities that open up post-commercial.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;On the high end, you could just rent or buy time to ATP mins, but that could cost a fortune.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the low end you could work to ATP mins and make some money.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A good way to make money with a fresh commercial/cfi ticket is to instruct. There are also jobs like banner towing or pipeline/powerline patrol you could do, but you probably still need to build time beyond commercial mins to be competitive for those jobs.  You also mention cropdusting, but keep in mind many of those ops are turbine powered ag-cats and you won't be competitive there with a fresh commercial ticket.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;*&lt;sub&gt;You can do it cheaper but I'm giving these numbers because a fast but expensive program may appeal to a career changer.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-24T17:56:44.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1307" PostTypeId="2" ParentId="1256" CreationDate="2014-01-24T22:31:28.550" Score="3" Body="&lt;p&gt;Lycoming engines have the camshaft above the crankshaft, and Continental engines have the cam below the crankshaft.  This seems to keep the Conti cams better oiled and therefore less susceptible to corrosion. &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-24T22:31:28.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1308" PostTypeId="2" ParentId="1265" CreationDate="2014-01-25T02:52:10.883" Score="12" Body="&lt;p&gt;You haven't provided everything possible to really ascertain the issue noted, but based on what you have I've noticed the following things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You'll find most 737s at 240-250 KIAS passing through 10000 feet, rather than the 220 knots that you were going at (while 220 KIAS is above minimum clean speed at normal landing weights, it's still slower than most)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Being heavy actually makes minimum drag and max L/D speeds higher, which means that for the same speed, you'll actually descend at &lt;em&gt;less&lt;/em&gt; of a gradient than if you were lighter&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Boeing 737-800W has a idle descent ratio of about 1:20, which means that at 250 knots you're only going to be descending about 1200fpm -- the 737-800 (especially with winglets) is a very slick bird.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For your reference, you can see the distances required for an idle descent (.78/280/250), plus allowances for a straight-in approach:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;|=====================================================|&#xA;|          |       |      |       DISTANCE (NM)       |&#xA;| PRESSURE |       |      |---------------------------|&#xA;| ALTITUDE | TIME  | FUEL |  LANDING WEIGHT (1000 KG) |&#xA;|   (FT)   | (MIN) | (KG) |  40  |  50  |  60  |  70  |&#xA;|----------|-------|------|------|------|------|------|&#xA;|   41000  |   27  |  340 |  102 |  119 | 133  |  142 |&#xA;|   39000  |   26  |  340 |   97 |  114 | 127  |  136 |&#xA;|   37000  |   25  |  330 |   92 |  108 | 121  |  130 |&#xA;|   35000  |   24  |  330 |   88 |  103 | 116  |  125 |&#xA;|   33000  |   24  |  320 |   84 |   99 | 111  |  120 |&#xA;|   31000  |   23  |  320 |   80 |   94 | 105  |  113 |&#xA;|   29000  |   22  |  310 |   75 |   88 |  98  |  106 |&#xA;|   27000  |   21  |  300 |   70 |   82 |  92  |   99 |&#xA;|   25000  |   20  |  300 |   66 |   77 |  86  |   92 |&#xA;|   23000  |   19  |  290 |   61 |   71 |  79  |   85 |&#xA;|   21000  |   18  |  280 |   57 |   66 |  73  |   78 |&#xA;|   19000  |   17  |  270 |   52 |   61 |  67  |   72 |&#xA;|   17000  |   15  |  250 |   48 |   55 |  61  |   65 |&#xA;|   15000  |   14  |  240 |   44 |   50 |  55  |   58 |&#xA;|   10000  |   11  |  200 |   30 |   34 |  37  |   39 |&#xA;|    5000  |    7  |  150 |   18 |   19 |  20  |   21 |&#xA;|    1500  |    4  |  110 |    9 |    9 |   9  |    9 |&#xA;|=====================================================|&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-01-25T02:52:10.883" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1311" PostTypeId="1" AcceptedAnswerId="1312" CreationDate="2014-01-25T04:08:50.533" Score="20" ViewCount="2466" Body="&lt;p&gt;I just flew into Bravo unintentionally 48 hours ago. My error: I thought I was 1,500 feet above the ceiling, but I was 1,000 feet below it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, I had an incorrect frequency for Approach, and while I eventually found the proper frequency (I'd planned to request flight following) I had crossed over the outer ring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I contacted Approach, the Approach Controller explained I was in Bravo, and to turn West and exit. I did say, &quot;Am I not ABOVE Bravo airspace?&quot; He said &quot;No, you're in it&quot; and to fly West and exit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From that moment, I followed approach control's directions to a T, but could not understand why he directed me West (remaining in Class B for 13 more miles) instead of having me climb 1,500 feet or angle back North or North-West to exit Bravo more quickly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was given the dreaded phone number, made the call after landing, had a friendly enough discussion, and he said it would probably lead to a counseling session. My question is what is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm familiar with the remedial training option the FAA may offer, but what did he mean by &quot;counseling session&quot;? The controller implied it would be handled by phone. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not freaking yet, just concerned. I told everything that happened on that phone call, and then filed an ASRS report.&lt;/p&gt;&#xA;" OwnerUserId="699" LastEditorUserId="97" LastEditDate="2014-03-21T04:00:53.760" LastActivityDate="2014-03-21T04:00:53.760" Title="What is a counseling session with the FSDO/FAA?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;airspace&gt;&lt;class-b-airspace&gt;&lt;fsdo&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1312" PostTypeId="2" ParentId="1311" CreationDate="2014-01-25T05:31:45.000" Score="17" Body="&lt;p&gt;A &quot;Counseling Session&quot; is the lightest slap on the wrist the FAA can give you (aside from doing nothing).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it means &quot;you screwed up, you know you screwed up, and &lt;em&gt;we (the FAA) know you know you screwed up&lt;/em&gt;&quot; -- they just want to sit you down with someone from the FSDO (probably a FAA Safety Team representative) and have a conversation to make sure everyone is clear on what happened, &lt;em&gt;how&lt;/em&gt; the violation happened and that you know how you can avoid this sort of thing happening in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that counseling sessions are &quot;informal&quot; (they're not an official &quot;administrative action&quot;, so I'm pretty sure they don't go on your airman record) - the FSDO will note that they talked to you and bury that tidbit in their internal file, to be generally forgotten unless you decide to make a habit of busting airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The closest &quot;official documentation&quot; I can find on counseling sessions is in the &lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/270/1207/Representative%20Manual.pdf&quot;&gt;FAA Safety Team's Representative Manual&lt;/a&gt; -- Page 12 if you're interested.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some things to bear in mind:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You're the kind of pilot the FAA isn't out to beat up on.&lt;br&gt;&#xA;Yes, you screwed up - but you know that and you clearly want to make sure you don't do it again, which is really all they want too. &lt;/li&gt;&#xA;&lt;li&gt;Make sure you're clear in your mind what happened &amp;amp; how to avoid similar incidents in the future.&lt;br&gt;&#xA;Did you misread the chart? The altimeter? Get distracted looking up the frequency? Something else?&lt;/li&gt;&#xA;&lt;li&gt;Don't admit to any &lt;em&gt;other&lt;/em&gt; violations during the counseling session.&lt;br&gt;&#xA;(Presumably you didn't commit any, you got a proper flight briefing, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Hang on to your ASRS strip.&lt;br&gt;&#xA;You won't need it for a counseling session, though mentioning you've filed an ASRS report won't hurt anything. If the FAA opts for a more formal action that strip is going to be important.&lt;/li&gt;&#xA;&lt;li&gt;If you have &lt;a href=&quot;https://pilot-protection-services.aopa.org&quot;&gt;AOPA pilot protection services&lt;/a&gt; now would be a good time to chat with them too, just to cover all your bases.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-25T05:31:45.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1313" PostTypeId="1" AcceptedAnswerId="1316" CreationDate="2014-01-25T05:39:13.933" Score="10" ViewCount="197" Body="&lt;p&gt;If I want to launch high power rockets NOT at a NAR or TRA sanctioned launch, assuming I am properly certified, what do I need to do?  I looked in the FAR|AIM, but I couldn't find anything on rockets, but I think the rocketry section has been omitted from the PPT FAR|AIM.&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="69" LastEditDate="2014-01-25T06:33:37.810" LastActivityDate="2014-01-25T06:33:37.810" Title="What type of hoops do I have to jump through to launch high power rockets?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1314" PostTypeId="1" AcceptedAnswerId="1317" CreationDate="2014-01-25T05:44:27.177" Score="12" ViewCount="3692" Body="&lt;p&gt;If I'm flying along in my C-152 and I am trying to go in a straight line through the &quot;center&quot; of C airspace (to land at a regional airport under the airspace), but the controller tells me to remain clear, what should I do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be safe to fly under the C, or above it, or would it be best to completely circle around even if it takes extra time and fuel?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="69" LastEditDate="2014-01-25T06:23:52.927" LastActivityDate="2014-04-21T21:51:08.933" Title="I've been denied VFR clearance through C airspace, what should I do?" Tags="&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1315" PostTypeId="2" ParentId="1314" CreationDate="2014-01-25T06:16:19.883" Score="3" Body="&lt;p&gt;When the controller tells you to &quot;remain clear&quot; it simply means that he is too busy to help you out at the moment.  Traffic situations change quickly though, so I would recommend taking the most direct route that you can while remaining outside of his airspace and when things sound like they have quieted down a little, give him another try.  If it isn't feasible (you are landing at the primary airport, or you need to enter it to get to the other airport) then you can circle until things calm down for the controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the airport that you are wanting to land at is under the Class C airspace anyway, probably the best way would be to go ahead and descend a little earlier than you had planned and fly under the shelf.  Assuming that you have sufficient terrain clearance it would probably be better than flying over the top since you have to go down there anyway.  That being said, there's no reason not to fly over the top if it's more convenient!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In either case, the main thing to watch for is arrival and departure traffic for the primary airport.  The controller basically told you that there is a lot of it.  If you are instrument rated, take a look at the arrival and departure procedures so that you can try to avoid them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just be sure that you don't accidentally fly into his airspace without a clearance and you should be fine!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-25T06:23:03.563" LastActivityDate="2014-01-25T06:23:03.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1316" PostTypeId="2" ParentId="1313" CreationDate="2014-01-25T06:32:53.573" Score="8" Body="&lt;p&gt;The FAR section that you are looking for is available on the ecfr website:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.15&amp;amp;idno=14&quot;&gt;PART 101—MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More specifically, it is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.15&amp;amp;idno=14#14:2.0.1.3.15.3&quot;&gt;Subpart C— Amateur Rockets&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main regulations that apply are (see the above link for the full text of the regulations):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§101.23   General operating limitations.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) You must operate an amateur rocket in such a manner that it:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Is launched on a suborbital trajectory;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) When launched, must not cross into the territory of a foreign&#xA;  country unless an agreement is in place between the United States and&#xA;  the country of concern;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Is unmanned; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Does not create a hazard to persons, property, or other aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The FAA may specify additional operating limitations necessary to&#xA;  ensure that air traffic is not adversely affected, and public safety&#xA;  is not jeopardized.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§101.25   Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When operating Class 2-High Power Rockets or Class 3-Advanced High&#xA;  Power Rockets, you must comply with the General Operating Limitations&#xA;  of §101.23. In addition, you must not operate Class 2-High Power&#xA;  Rockets or Class 3-Advanced High Power Rockets—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) At any altitude where clouds or obscuring phenomena of more than&#xA;  five-tenths coverage prevails;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) At any altitude where the horizontal visibility is less than five&#xA;  miles;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Into any cloud;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Between sunset and sunrise without prior authorization from the&#xA;  FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Within 9.26 kilometers (5 nautical miles) of any airport boundary&#xA;  without prior authorization from the FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) In controlled airspace without prior authorization from the FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) Unless you observe the greater of the following separation&#xA;  distances from any person or property that is not associated with the&#xA;  operations:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Not less than one-quarter the maximum expected altitude;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) 457 meters (1,500 ft.);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) Unless a person at least eighteen years old is present, is charged&#xA;  with ensuring the safety of the operation, and has final approval&#xA;  authority for initiating high-power rocket flight; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Unless reasonable precautions are provided to report and control a&#xA;  fire caused by rocket activities.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§101.27   ATC notification for all launches.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may operate an unmanned rocket other than a Class 1—Model&#xA;  Rocket unless that person gives the following information to the FAA&#xA;  ATC facility nearest to the place of intended operation no less than&#xA;  24 hours before and no more than three days before beginning the&#xA;  operation:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§101.29   Information requirements.&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-25T06:32:53.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1317" PostTypeId="2" ParentId="1314" CreationDate="2014-01-25T06:37:46.500" Score="23" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If I'm flying along in my C-152 and I am trying to go in a straight line through the &quot;center&quot; of C airspace, but the controller tells me to remain clear, what should I do?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, the obvious answer is &lt;strong&gt;&lt;em&gt;remain clear of the Class C airspace&lt;/em&gt;&lt;/strong&gt; :-)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;HOW&lt;/em&gt; you remain clear is entirely up to you - you can go over, under, or around - you just can't go &lt;em&gt;through&lt;/em&gt;, and I think that's the more interesting part of your question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Flying around the class C airspace is usually a safe choice (&lt;em&gt;don't&lt;/em&gt; skim along the margins though - give it some reasonable breathing room), but as you've noted it could add a lot of time/fuel. You need to balance that with the time/fuel required to climb above the airspace, or the risks of flying under the airspace (mainly obstacles) to make your decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm going to use my local class C airspace as an example for an exercise in aeronautical decision making because conveniently there's a VOR you could hypothetically be circling while talking to approach, and an airport on the other side you might want to get to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In our hypothetical example let's say you're circling Deer Park VOR (&lt;code&gt;A&lt;/code&gt;) at 2500 feet, and you want to cut through the Class C airspace to get to Brookhaven (&lt;code&gt;B&lt;/code&gt;), but approach isn't cooperating.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zLPH0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zLPH0m.jpg&quot; alt=&quot;Islip class C&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Click to embiggen.&lt;/sup&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've got three options sketched out here - think about them, then hover over the spoiler boxes for my thinking on each of the three routes:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The dashed line through the center (the route you were hoping Approach would give you).&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; A straight line is the shortest distance between two points, but this straight line stinks: Since Approach wouldn't let you go through the class C airspace you're going to have to spiral-climb to 4200 feet or higher (5500 feet if you're playing by the hemispheric rule), and then when you get to the cut-out in the class C on the other side you're going to have to dive down to get to pattern altitude.&lt;br&gt;&#xA;That doesn't seem safe, nor efficient to me, so let's toss that idea out the window.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The northern route under the class C airspace.&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; Simple enough, we'll split the difference between the ground (roughly sea level) and the floor of the airspace (1500 feet) and fly under the shelf at 1250 feet. Plenty of room above and below (if your altimeter is set right and you're any kind of decent pilot).&lt;br&gt;&#xA; So this is the part where I confess that I'm a big ol' wuss and don't like to be close to the ground. It's like a porcupine, but with radio towers for quills (like the one I marked with a big &lt;strong&gt;OUCH&lt;/strong&gt; - at 1250 feet there'd be less than 500 feet between my landing gear and the top of that tower).&lt;br&gt;&#xA; I'm not happy with the obstacle clearance on this route (and while I could certainly rearrange the line a bit to avoid the obstacles I'm not going to because they serve my purpose) -- the northern route is out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The southern route under the class C airspace.&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; Same idea as the northern route - descend to 1250 feet and fly under the shelf, but I like this route a whole lot better.&lt;br&gt;&#xA; There are really great landmarks here (&quot;Fly southeast toward the looped road, then go to the middle of the bay and stay between the two shore lines until you pass the bridge at Smith Point. At that point you'll see the airport off your left wing and can maneuver to enter the pattern.&quot;)&lt;br&gt;&#xA; You're also over water, and we don't tend to have any radio towers sticking up out of the bay.&lt;br&gt;&#xA; You'll need to watch out for traffic from Bayport, students practicing ground-reference maneuvers, and banner-tow planes in the summer, but that's just your basic everyday VFR &quot;See and Avoid&quot; situation.&lt;br&gt;&#xA; This is probably the route I'd pick.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-25T06:37:46.500" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1318" PostTypeId="1" AcceptedAnswerId="1319" CreationDate="2014-01-25T11:53:32.217" Score="20" ViewCount="926" Body="&lt;p&gt;I'm a low time PPL.  In my personal opinion, practice &lt;a href=&quot;http://en.wikipedia.org/wiki/Pan-pan&quot; rel=&quot;noreferrer&quot;&gt;pans&lt;/a&gt;, perhaps one or two a year, are a good thing.  Practice in a procedure that builds confidence removes one more item from the pucker factor list if it does all go wrong and lets your brain focus on the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The D&amp;amp;D cell are always happy to assist and I know that they welcome it as it gives them practice as much as it does me. They are always excellent and it's comforting to know that they are there if I ever need them for real.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I know that many pro pilots do not approve of this.  I am aware that they are often required to monitor guard and that practice pans can be a source of noise but is it really that disturbing?  I've even had that terse &quot;transmitting on guard&quot; broadcast which to me is a) entirely rhetorical and b) great irony.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If something genuine crops up on guard, then of course I'd shut up and continue on my way but are there any &lt;strong&gt;genuine&lt;/strong&gt; reasons for amateurs to not practice?  Surely it's better for all users of the sky to be as good as they can?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="572" LastEditDate="2015-04-17T06:05:45.050" LastActivityDate="2015-04-17T06:05:45.050" Title="Practice Pans - are there any genuine reasons not to use them?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;radio-communications&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1319" PostTypeId="2" ParentId="1318" CreationDate="2014-01-25T13:05:51.327" Score="16" Body="&lt;p&gt;I presume you are from UK since it is the only country I know of that uses practice pans. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, ICAO (ICAO Annex 10, Volume V, § 4.1.3.1.1) states that the emergency frequency 121.5 MHz (sometimes called &quot;guard&quot;) shall be used only for genuine emergencies. So typically any other use is considered misuse. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, countries can file deviations from this rule and publish these deviations in their AIP. One such example is the UK, where 121.5 can be used for practice PAN calls to ensure pilot familiarity with the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots not familiar with the situation in the UK sometimes frown upon this use, and as you mention, jump in with the dreaded &quot;transmitting on guard&quot; sentence. But those doing that seem to have the same reaction when a real emergency is going on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying in the UK and want to practice an emergency situation you are &lt;a href=&quot;http://www.caa.co.uk/docs/33/srg_gad_D&amp;amp;D_poster.pdf&quot;&gt;encouraged&lt;/a&gt; to do so by the D&amp;amp;D cells. But remember to ask permission first:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A/C &gt; London Centre, &lt;em&gt;callsign&lt;/em&gt;, request Practice Pan&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If they have the time to accommodate you, the reply will be something like&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;London &gt; &lt;em&gt;callsign&lt;/em&gt;, Practice Pan acknowledged, continue when ready &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And remember, it is not only a practice for you, but also for controllers. There is a benefit for everyone flying around.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-25T13:05:51.327" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1320" PostTypeId="1" AcceptedAnswerId="1322" CreationDate="2014-01-25T14:49:42.457" Score="11" ViewCount="12710" Body="&lt;p&gt;We all get sick, suffer from allergies and sometimes chronic issues.  It is not safe to fly while on some medicines or in some cases, for some time after taking the medicine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do I know what I can take and still fly?  What resources are out there to check if a specific medicine is compatible with flying (AOPA, FAA, etc)?  Is there a comprehensive list of what I can and cannot take?&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="97" LastEditDate="2014-03-21T03:58:08.017" LastActivityDate="2016-07-18T17:49:10.027" Title="What medications may pilots take while flying?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;medical&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1321" PostTypeId="1" AcceptedAnswerId="1338" CreationDate="2014-01-25T14:57:23.983" Score="7" ViewCount="17680" Body="&lt;p&gt;Exemption 3585 allows 121 carriers (and perhaps others) to dispatch to destinations in certain cases with weather below minimums.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the forecast weather minimums to be dispatched under exemption 3585?  When is it required to have a second alternate listed on the release?  What are the forecast weather requirements at the two alternates?  What is the regulatory basis for this exemption?&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-26T00:50:33.130" Title="Can someone explain Exemption 3585?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;airline-operations&gt;&lt;dispatch&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1322" PostTypeId="2" ParentId="1320" CreationDate="2014-01-25T15:00:41.000" Score="9" Body="&lt;p&gt;AOPA has the best database that I know of, but you have to be a member to view it.  They have some free information on their &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/FAA-Policy.aspx&quot; rel=&quot;nofollow&quot;&gt;Medications&lt;/a&gt; page though. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There they talk about FAA Policy, and it starts with:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Federal Aviation Regulations include no specific references to&#xA;  medication usage. FAR 61.53 prohibits acting as pilot-in-command or in&#xA;  any other capacity as a required pilot flight crewmember, while that&#xA;  person:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Knows or has reason to know of any medical condition that would make the person unable to meet the requirement for the medical certificate&#xA;  necessary for the pilot operation, or:&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Is taking medication or receiving other treatment for a medical condition that results in the person being unable to meet the&#xA;  requirements for the medical certificate necessary for the pilot&#xA;  operation. Further, FAR 91.17 prohibits the use of &quot;any drug that&#xA;  affects the persons faculties in any way contrary to safety.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.aviationmedicine.com/medication-database/&quot; rel=&quot;nofollow&quot;&gt;AMAS&lt;/a&gt; (Aviation Medicine Advisory Service) also has a list (which is free) but I don't think that it is organized as well.  They are recommended by ALPA and NBAA though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important thing though, of course, is to self evaluate and make sure that you don't fly if you are having any adverse reactions from the medication, &lt;em&gt;or the underlying condition&lt;/em&gt; that you are taking the medicine for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any list that you consult has to be used only as a guide though, and not a carte-blanche approval.  Individual people can have reactions even to medications that are considered &quot;safe&quot; and &quot;allowed&quot; by the FAA, and this is why they don't list specific medications that they allow.  The FAA has a brochure called &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Meds_brochure.pdf&quot; rel=&quot;nofollow&quot;&gt;Medications and Flying&lt;/a&gt;, and one part of it has a few things to consider before taking any medication:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First, consider the underlying condition  that you are treating. What&#xA;  will be the  consequences if the medication doesn’t work  or if it&#xA;  wears off before the ﬂight is over?  A good general rule to follow is&#xA;  not to ﬂy  if you must depend on the medication to  keep the ﬂight&#xA;  safe. In other words, if the  untreated condition is one that would&#xA;  prevent  safe ﬂying, then you shouldn’t ﬂy until the  condition&#xA;  improves — whether you take the  medication or not.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Second, you must &lt;strong&gt;consider your reaction to  the medication&lt;/strong&gt;. There&#xA;  are two broad categories  of medication reactions. One is a unique&#xA;  reaction  based on an individual’s biological make-up.  Most people&#xA;  don’t have such reactions but  anyone can, given the right medication.&#xA;  Because  of this, you should NEVER ﬂy after taking any  medication&#xA;  that you have not taken before. It  is not until after you have taken&#xA;  the medication  that you will ﬁnd out whether you have this  uncommon&#xA;  and unexpected reaction to the  medication.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Third, &lt;strong&gt;consider the potential for adverse  reactions,&lt;/strong&gt; or side&#xA;  effects — unwanted reactions  to medications. This type of reaction is&#xA;  quite common, and the manufacturer of the  medication lists these on&#xA;  the label. You MUST  carefully read all labeling. If you don’t have &#xA;  access to the label, then don’t ﬂy while using the  medication. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Look for such key words as lightheadedness,  dizziness, drowsiness, or&#xA;  visual disturbance. If  these side effects are listed or if the label&#xA;  contains  any warning about operating motor vehicles or  machinery,&#xA;  then you should not ﬂy while using  the medication. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Side effects can occur at any time, so even if  you’ve taken the same&#xA;  medication in the past  without experiencing side effects, they could&#xA;  still  occur the next time. For this reason, you must  never ﬂy after&#xA;  taking a medication with any of  the above-noted side effects.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-07-18T17:49:10.027" LastActivityDate="2016-07-18T17:49:10.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1323" PostTypeId="1" CreationDate="2014-01-25T17:33:52.090" Score="16" ViewCount="6222" Body="&lt;p&gt;Suppose the max crosswind rated for my C-182 is 15kts, but the wind is directly across and gusting to 20kts.  Is it legal for me to go? I've heard plenty hangar flying stories of many an operation that exceeds the design specifications of certain planes that end successfully. &lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="97" LastEditDate="2014-01-25T20:51:48.990" LastActivityDate="2018-11-15T11:59:26.877" Title="Is it legal to takeoff in a crosswind that exceeds the design limit of my aircraft?" Tags="&lt;takeoff&gt;&lt;aircraft-limitations&gt;&lt;crosswind&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1324" PostTypeId="2" ParentId="1323" CreationDate="2014-01-25T18:03:00.690" Score="15" Body="&lt;p&gt;The 15kt crosswind for the 182 is not a design limit at all. If it were a design limit, it would be specifically stated in the POH. To be honest, I think there's no such thing as a design limit for crosswind. It all comes down to how much rudder authority there's left at a specific crosswind strength. And even that depends on many factors like approach speed, flap settings, weight, CG, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what the POH for the C182T says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Demonstrated Crosswind Velocity is the velocity of the crosswind&#xA;  component for which adequate control of the airplane during takeoff&#xA;  and landing was actually demonstrated during certification tests. The&#xA;  value shown is not considered to be limiting.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The maximum allowable crosswind velocity is dependent upon pilot&#xA;  capability as well as airplane limitations. Operation in direct&#xA;  crosswinds of 15 knots has been demonstrated&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is perfectly legal to land and takeoff with a stronger crosswind component. It's up to the pilot to determine if it's safe to do so or not. It all depends what the pilot's capabilities are.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-01-25T18:34:31.187" LastActivityDate="2014-01-25T18:34:31.187" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1326" PostTypeId="1" AcceptedAnswerId="1337" CreationDate="2014-01-25T19:52:59.443" Score="10" ViewCount="3905" Body="&lt;p&gt;Watching the first episode of &lt;a href=&quot;http://www.youtube.com/watch?v=GziV0efQrN4&quot; rel=&quot;noreferrer&quot;&gt;Dangerous Flights&lt;/a&gt;, a ferry pilot has aftermarket fuel tanks fitted inside the cabin of an old Merlin IIB:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nirOym.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the regulatory requirements to be able to do this? / How can you get permission to fit extra tanks inside a plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anything that needs to be specially considered when designing the tanks and valves etc?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this commonplace when ferry flying long-haul?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-25T19:58:40.680" LastActivityDate="2014-01-25T23:41:18.477" Title="What regulations surround fitting aftermarket fuel tanks inside the cabin?" Tags="&lt;faa-regulations&gt;&lt;modifications&gt;&lt;fuel-tanks&gt;&lt;ferry-flight&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1327" PostTypeId="5" CreationDate="2014-01-25T20:01:16.770" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-25T20:01:16.770" LastActivityDate="2014-01-25T20:01:16.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1328" PostTypeId="4" CreationDate="2014-01-25T20:01:16.770" Score="0" Body="Ferry flights are delivery flights for the purpose of returning an aircraft to base, delivering a new aircraft from its place of manufacture to its customer, moving an aircraft from one base of operations to another or moving an aircraft to or from a maintenance facility for repairs, overhaul or other work." OwnerUserId="97" LastEditorUserId="69" LastEditDate="2014-01-25T23:11:20.100" LastActivityDate="2014-01-25T23:11:20.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1329" PostTypeId="5" CreationDate="2014-01-25T20:09:27.953" Score="0" Body="&lt;p&gt;The US DoD &lt;a href=&quot;http://www.thefreedictionary.com/aircraft+modification&quot; rel=&quot;nofollow&quot;&gt;defines&lt;/a&gt; this as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A change in the physical characteristics of aircraft, accomplished either by a change in production specifications or by alteration of items already produced&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-26T02:20:22.393" LastActivityDate="2014-01-26T02:20:22.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1330" PostTypeId="4" CreationDate="2014-01-25T20:09:27.953" Score="0" Body="Questions relating to aircraft modifications" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-26T02:20:30.393" LastActivityDate="2014-01-26T02:20:30.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1331" PostTypeId="1" AcceptedAnswerId="1334" CreationDate="2014-01-25T20:44:40.230" Score="24" ViewCount="5882" Body="&lt;p&gt;Let's say that you're on approach to a remote airport to refuel (for arguments sake, &lt;a href=&quot;https://en.wikipedia.org/wiki/Funafuti_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Funafuti International Airport&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tuvalu&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tuvalu&lt;/a&gt;), with 1-2 hours of fuel remaining in your aircraft. Contacting ATC to request permission to land, they tell you that the only runway is closed for an unspecified reason and will not reopen for ~2 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://secure.universalweather.com/regusers/flightplanning2/tools/alt_finder/alternates.html?airport=NGFU&amp;amp;radius=500&quot; rel=&quot;nofollow noreferrer&quot;&gt;The nearest airport is 295nm away&lt;/a&gt;, so you agree to hold, hoping the runway is soon reopened. After waiting a little while, the runway is still not reopened, so you declare an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the airport required to reopen the runway? Does the fact that the nation is not a part of &lt;a href=&quot;https://en.wikipedia.org/wiki/Convention_on_International_Civil_Aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Chicago Convention&lt;/a&gt; change anything?*&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supposing ATC refuse to reopen the runway, is the pilot permitted to land anyway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's presume the aircraft is not certified for ditching.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Searching Google, I found that &lt;a href=&quot;http://www.flightglobal.com/news/articles/low-fuel-forced-italian-md-82-to-land-on-closed-runway-316861/&quot; rel=&quot;nofollow noreferrer&quot;&gt;at least one&lt;/a&gt; emergency aircraft has landed on a closed runway.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;* &lt;strong&gt;2020 update:&lt;/strong&gt; in Nov 2017 Tuvalu became ICAO's 192nd member state (&lt;a href=&quot;https://www.icao.int/Newsroom/Pages/Tuvalu-becomes-ICAOs-192nd-Member-State.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;icao.int&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="14897" LastEditDate="2020-01-14T22:17:54.837" LastActivityDate="2020-03-05T14:00:05.220" Title="May an emergency aircraft land on a closed runway?" Tags="&lt;air-traffic-control&gt;&lt;emergency-procedures&gt;&lt;icao&gt;&lt;closed-runways&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="1332" PostTypeId="2" ParentId="170" CreationDate="2014-01-25T20:56:23.737" Score="44" Body="&lt;p&gt;This headline made the news this week: &lt;a href=&quot;http://gizmodo.com/passenger-snaps-photo-of-fuel-pouring-out-of-a-dreamlin-1506027806&quot; rel=&quot;noreferrer&quot;&gt;Passenger Snaps Photo of Fuel Pouring Out of a Dreamliner's Wing&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The passenger, Ann Kristin Balto from Tromsø, noticed the highly disconcerting leak as the plane was taxiing to the runway—before it actually took off. After alerting the stewardess, the flight was immediately cancelled.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LWuYS.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So fuel leaks are one thing you could look out for!&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-27T00:47:45.270" LastActivityDate="2014-01-27T00:47:45.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1333" PostTypeId="2" ParentId="1331" CreationDate="2014-01-25T21:01:37.657" Score="16" Body="&lt;p&gt;If you already declared an emergency all bets are off, and you must do whatever is required to save the vehicle. There can be no talk about being 'permitted' or even 'cleared' to land if an emergency has been declared.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO Annex 2 2.3.1 Responsibility of pilot-in-command&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot-in-command of an aircraft shall, whether manipulating the&#xA;  controls or not, be responsible for the operation of the aircraft in&#xA;  accordance with the rules of the air, except that the pilot-in-command&#xA;  &lt;strong&gt;may depart from these rules&lt;/strong&gt; in circumstances that render such&#xA;  departure absolutely necessary &lt;strong&gt;in the interests of safety&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-01-25T21:01:37.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1334" PostTypeId="2" ParentId="1331" CreationDate="2014-01-25T22:47:43.353" Score="45" Body="&lt;h1&gt;Preflight Planning&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's say that you're on approach to a remote airport to refuel, with&#xA;  1-2 hours of fuel remaining in your aircraft. ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The nearest airport is 3-4 hours away...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;First of all, it looks as if the pilot has already broken several regulations in order to end up in this situation.  He either didn't file an alternate, or if he did then he didn't carry enough fuel to get to it (and additional reserves as required).  If the runway is closed for an extended period of time, there would likely have been a NOTAM stating that the runway would be closed.  All of this sounds like poor preflight planning, and probably the 'ole careless and reckless thrown in for good measure.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The Problem&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Contacting ATC to request permission to land, they tell you that the only runway is&#xA;  closed for an unspecified reason and will not reopen for ~2 hours.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Okay, we need to figure out what the &quot;unspecified reason&quot; is because this can change things dramatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dailymail.co.uk/travel/article-2009791/JFK-Turtles-Flights-delays-New-York-airport-mating-turtles.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1FTBPm.jpg&quot; alt=&quot;turtles at airport&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Is it for endangered migrating turtles?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.panoramio.com/photo/13129957&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8kkOCm.jpg&quot; alt=&quot;runway construction&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Is it for construction?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, he needs to use all available resources.  Talk to ATC and explain the situation. Ask them how they can help clear the runway so that we can land.  He should tell them that an emergency is imminent without their assistance.  They will do everything that they can to help you, including coordinating with people on the ground to get out of the way.  Be creative.  Did you know that there is no regulation (in the US) requiring you to land on an actual runway?  Ask them if you can land on the taxiway.  For that matter, land in the grass beside the runway.  It would be better than going for a swim or crashing after running out of gas!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's presume the airport is surrounded by ocean, and the aircraft is not certified for ditching.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ummm, &lt;strong&gt;&lt;em&gt;who cares&lt;/em&gt;&lt;/strong&gt; if it is certified for ditching?  If you are over water, it doesn't matter.  If you are over land, it doesn't matter.  If you have a choice, pick land (even if it's off-airport).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Supposing ATC refuse to reopen the runway, is the pilot permitted to land anyway?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, they wouldn't really do this unless there was a &lt;strong&gt;&lt;em&gt;really&lt;/em&gt;&lt;/strong&gt; good reason, mainly meaning that it would be dangerous for the aircraft to land there (like in the second picture above).  In this case, we can't really ignore ATC and land anyway &lt;em&gt;until&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Declaring the Emergency&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...so you choose to hold, hoping the runway is soon reopened. After&#xA;  waiting a while, the runway is still not reopened, so you declare an&#xA;  emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;At least our poor pilot did this right.  Rather than blindly continuing to hold, he declared an emergency.  &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Getting on the Ground&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Now we have a lot more latitude and options, and ATC is better able to help us because they can pretty much do &lt;em&gt;whatever it takes&lt;/em&gt; to save the aircraft.  This can change a &quot;&lt;em&gt;Sorry, there is nothing I can do.&lt;/em&gt;&quot; into a &quot;&lt;em&gt;Cleared to land any runway or taxiway.&lt;/em&gt;&quot; all on its own. They may throw in a &quot;&lt;em&gt;Landing at your own risk.&lt;/em&gt;&quot; if there are still hazards, but that's just to clear them of liability.  Even if they still refuse, you can simply advise them of what you will be doing and go ahead and do it.  &lt;strong&gt;Keep in mind however, that it may be better to scope out an off-airport landing site if the danger is so great that ATC won't allow you to land even under such dire circumstances.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the &lt;strong&gt;&lt;em&gt;pilot&lt;/em&gt;&lt;/strong&gt; is the final authority for safe operation of the aircraft.  Get on the ground and sort it out after the fact. (Poor turtles....)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, just do what you can to stay alive, and preferably use the airplane again.  There are going to be tons of questions and probably major legal battles.  Someone will probably go after the pilot's certificate.  On the bright side, he will be around to actually see it happen though.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-25T23:02:31.550" LastActivityDate="2014-01-25T23:02:31.550" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1335" PostTypeId="5" CreationDate="2014-01-25T23:16:13.503" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Convention_on_International_Civil_Aviation&quot; rel=&quot;nofollow&quot;&gt;Convention on International Civil Aviation&lt;/a&gt;, also known as the Chicago Convention, established &lt;a href=&quot;/questions/tagged/icao&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;icao&amp;#39;&quot; rel=&quot;tag&quot;&gt;icao&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All United Nations states - except Dominica, Liechtenstein, and Tuvalu - plus the Cook Islands have signed the treaty.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-25T23:25:39.387" LastActivityDate="2014-01-25T23:25:39.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1336" PostTypeId="4" CreationDate="2014-01-25T23:16:13.503" Score="0" Body="The international rules of airspace for all member nations (most of the world)." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-01-25T23:25:50.217" LastActivityDate="2014-01-25T23:25:50.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1337" PostTypeId="2" ParentId="1326" CreationDate="2014-01-25T23:25:22.637" Score="11" Body="&lt;p&gt;This is covered by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=ec0b21ef66eb658579d21358621c749d&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.3.7.2&amp;amp;idno=14&quot;&gt;14 CFR 91.203&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.203   Civil aircraft: Certifications required.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No person may operate an aircraft with a fuel tank installed&#xA;  within the passenger compartment or a baggage compartment unless the&#xA;  installation was accomplished pursuant to part 43 of this chapter, and&#xA;  a copy of FAA Form 337 authorizing that installation is on board the&#xA;  aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;tpl=/ecfrbrowse/Title14/14cfr43_main_02.tpl&quot;&gt;14 CFR 43&lt;/a&gt; covers MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, it needs to be an approved installation that is signed off and approved by the FAA using a &lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/documentlibrary/media/form/faa337.pdf&quot;&gt;Form 337&lt;/a&gt; - MAJOR REPAIR AND ALTERATION (Airframe, Powerplant, Propeller, or Appliance)&lt;/strong&gt;.  The maintenance shop will take care of that aspect for you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is pretty common for delivering aircraft that need to cross the ocean, and there are even companies that specialize in it.  Really, your only option is to purchase an already approved kit because certification costs are so high.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NBAA actually has a &lt;a href=&quot;http://www.nbaa.org/ops/maint/inoperative-equipment/special-flight-permit.php&quot;&gt;nice article&lt;/a&gt; which goes into more details, with lots of helpful links.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-25T23:41:18.477" LastActivityDate="2014-01-25T23:41:18.477" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1338" PostTypeId="2" ParentId="1321" CreationDate="2014-01-26T00:50:33.130" Score="6" Body="&lt;p&gt;Exemption 3585 is an exemption to 14 CFR 121 dispatch requirements for weather originally requested by Peoples Express.  Lots of airlines have requested similar approval, and here is an example on regulations.gov for &lt;a href=&quot;http://www.regulations.gov/contentStreamer?objectId=09000064814cdc0f&amp;amp;disposition=attachment&amp;amp;contentType=pdf&quot;&gt;Air Transportation International&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exemption that they asked and were approved for was:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...an exemption from &lt;strong&gt;§§ 121.613, 121.619(a), and 121.625&lt;/strong&gt; of Title&#xA;  14, Code of Federal Regulations (14 CFR) to the extent necessary to&#xA;  dispatch airplanes under instrument flight rules when conditional&#xA;  language in a one-time increment of the weather forecast states&#xA;  that the weather at the destination, alternate airport, or both&#xA;  airports could be below the authorized weather minimums when other&#xA;  time increments of the weather forecast state the weather conditions&#xA;  will be at or above the authorized weather minimums.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, if there is a conditional or temporary weather condition that is below minimums at the destination or the alternate airport at the flight's ETA&lt;sup&gt;1,2&lt;/sup&gt;, where the flight could not normally be released, they can depart under the 3585 exemption as long as a second alternate that is above required minimums&lt;sup&gt;3&lt;/sup&gt; is filed in the flight plan and enough fuel is carried to reach the furthest alternate plus the required 45 minute reserve.  There are a few other requirements too (training, manual and OpSpec revisions, etc.) but you can take a look at the letter to see them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exemption must be requested of and approved by the FAA for each air carrier that wants to use it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;em&gt;The forecast weather conditions at the destination airport must not be less&#xA;than one-half of the lowest weather minimum visibility value established&#xA;for the instrument approach procedure expected to be used at the&#xA;destination&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; &lt;em&gt;The forecast weather conditions at the first alternate airport must not be less than one-half of the alternate weather minimum ceiling and visibility values&#xA;specified in ATI’s operations specifications for that airport&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt; &lt;em&gt;With respect to the second alternate airport listed in the flight release&#xA;pursuant to this exemption, the METAR, the appropriate time increment of&#xA;the TAF, or any combination thereof for that airport must indicate in the&#xA;main body and remarks section of the METAR or TAF that the forecast&#xA;weather conditions will be at or above the alternate airport weather&#xA;minimum ceiling and visibility values specified in ATI’s operations&#xA;specifications for that airport&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-26T00:50:33.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1339" PostTypeId="1" CreationDate="2014-01-26T01:19:14.703" Score="12" ViewCount="2181" Body="&lt;p&gt;If someone does a contract flight, or a mechanic does contract maintenance for an aircraft owner and they refuse to pay after the fact, what options do they have to &quot;encourage&quot; the owner to pay?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the big problems is that this tends to happen informally:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Owner:&lt;/strong&gt; &quot;Hey, can you do this flight for me?&quot;&lt;br&gt;&#xA;  &lt;strong&gt;Pilot:&lt;/strong&gt; &quot;Sure, I charge $xxx.&quot; &quot;&lt;br&gt;&#xA;  &lt;strong&gt;Owner:&lt;/strong&gt; &quot;Okay, great.  See you on Monday morning at 9:00.&quot;&lt;br&gt;&#xA;  &lt;strong&gt;Pilot:&lt;/strong&gt; &quot;Sounds good, see you then.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So they show up, do the flight, send an invoice, and wait.  And wait..  And wait....  After a few weeks or 30 days, they send the invoice again.  Give it a bit and make a phone call.  Eventually it becomes clear that they just aren't that interested in paying a lone individual without the typical resources of a larger company.  Unfortunately, this happens more than you would think in this industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It probably isn't enough money to actually go out and hire a lawyer for, but it's irritating and &lt;strong&gt;they want their money&lt;/strong&gt;.  It's the principle!  I've heard of people placing a lien against the aircraft.  Is that something that an individual can do, or do you have to hire a lawyer?  Is small claims court an option?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for an answer that describes general approaches that can be taken, as obviously specific legal advice cannot be given without details of a situation like this.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-26T02:25:44.170" LastActivityDate="2018-07-06T04:38:35.817" Title="What options do pilots and mechanics have when an aircraft owner doesn't pay up?" Tags="&lt;usa&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1340" PostTypeId="2" ParentId="1339" CreationDate="2014-01-26T01:39:47.730" Score="15" Body="&lt;p&gt;You should be able &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/record_aircraft_lien/&quot; rel=&quot;noreferrer&quot;&gt;record a lien&lt;/a&gt; against the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Avionics News ran a &lt;a href=&quot;http://www.aea.net/AvionicsNews/ANArchives/LegalEaseMar09.pdf&quot; rel=&quot;noreferrer&quot;&gt;Legal Ease piece&lt;/a&gt; about just this, which is well worth reading fully:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If a lien is properly asserted, the lien claimant (the aircraft mechanic) has encumbered the aircraft in question, meaning the aircraft no longer has clear title.&lt;/p&gt;&#xA;&lt;p&gt;Clear title is highly desirable to an aircraft purchaser, who can determine if an aircraft has any liens on its title through a simple title search. Once there is a lien on an aircraft, to sell the aircraft with clear title, the aircraft owner must obtain a release from the lien claimant. This means the owner must pay you for your services before they are able to sell the aircraft with clear title.&lt;/p&gt;&#xA;&lt;p&gt;If the owner fails to pay the lien claimant to have the lien lifted, the aircraft will be sold subject to the lien. This means the aircraft does not have clear title, and although the aircraft will have a new owner, your lien will remain in effect.&lt;/p&gt;&#xA;&lt;p&gt;Most buyers, however, will not purchase an aircraft subject to a lien, and thus, you usually will manage to receive the money owed to you when the owner decides to sell the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;If you do not want to wait for the aircraft to be sold to satisfy your lien, you can bring a foreclosure proceeding, forcing the sale of the aircraft, usually at an auction.&lt;/p&gt;&#xA;&lt;p&gt;The proceeds from this sale go to the lien claimant to extinguish the lien. If the proceeds are greater than the lien, any money exceeding the amount of the lien goes to the aircraft owner. Additionally, if there are no bidders at the sale (an unusual occurrence), the aircraft may be given to the lien claimant for the price of the lien.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;One thing worth bearing in mind, is the &lt;a href=&quot;http://www.aerolienslist.com/claim_view.php&quot; rel=&quot;noreferrer&quot;&gt;Aero Liens List&lt;/a&gt; - a free resource which lists liens placed against aircraft owners. If your new client is on their &amp;quot;deadbeat client list&amp;quot; then you may want to think twice about doing the trip or get paid in advance!&lt;/p&gt;&#xA;&lt;p&gt;You asked whether a lien could be registered by a &lt;em&gt;pilot&lt;/em&gt; for lost wages (rather than a &lt;em&gt;mechanic&lt;/em&gt; for lost labour/parts); just searching the above list for &amp;quot;John&amp;quot;, I found at least one pilot who has two liens (against seperate companies) for lost wages: &lt;a href=&quot;http://www.aerolienslist.com/claim_deadbeat.php?id=376&quot; rel=&quot;noreferrer&quot;&gt;#1&lt;/a&gt; &lt;a href=&quot;http://www.aerolienslist.com/claim_deadbeat.php?id=376&quot; rel=&quot;noreferrer&quot;&gt;#2&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aerolienslist.com/claim_deadbeat.php?id=1094&quot; rel=&quot;noreferrer&quot;&gt;Another lien&lt;/a&gt; (PDF unavailable) lists its nature of the claim as &amp;quot;Salary owed&amp;quot;.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-01-26T02:10:01.750" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1341" PostTypeId="5" CreationDate="2014-01-26T02:27:27.677" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-26T02:27:27.677" LastActivityDate="2014-01-26T02:27:27.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1342" PostTypeId="4" CreationDate="2014-01-26T02:27:27.677" Score="0" Body="For questions relating to navigation charts, but not performance charts." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-26T03:33:13.937" LastActivityDate="2014-01-26T03:33:13.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1343" PostTypeId="1" AcceptedAnswerId="1393" CreationDate="2014-01-26T02:55:11.780" Score="9" ViewCount="6042" Body="&lt;p&gt;What does one need to do when a turboprop engine gets over-torqued? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't over-torqued an engine before, but it seems it could happen inadvertently, say while doing a go-around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Why is important &lt;em&gt;not&lt;/em&gt; to over-torque an engine?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What happens if you &lt;em&gt;do&lt;/em&gt; over-torque an engine?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="553" LastEditorUserId="97" LastEditDate="2014-01-27T04:50:18.840" LastActivityDate="2017-03-25T04:55:25.607" Title="What happens when a turbo-prop is over-torqued?" Tags="&lt;aircraft-maintenance&gt;&lt;turboprop&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1344" PostTypeId="5" CreationDate="2014-01-26T03:39:05.660" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-26T03:39:05.660" LastActivityDate="2014-01-26T03:39:05.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1345" PostTypeId="4" CreationDate="2014-01-26T03:39:05.660" Score="0" Body="An abbreviation of &quot;pilot report&quot;, which are reports of actual conditions experienced by pilots in a particular area." OwnerUserId="72" LastEditorUserId="69" LastEditDate="2014-01-26T03:52:50.677" LastActivityDate="2014-01-26T03:52:50.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1346" PostTypeId="2" ParentId="1323" CreationDate="2014-01-26T03:52:02.843" Score="5" Body="&lt;p&gt;&lt;strong&gt;NO&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not if it is actually a design limit.  In the case of the 182 it probably isn't actually a limit though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regard to crosswind information provided by the manufacturer, there are two different types.  For example, here are excerpts from the Falcon 50 AFM (which I happen to have handy):&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Demonstrated Crosswind Component&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Demonstrated Crosswind&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Satisfactory controllability during take-off and landing has been&#xA;  demonstrated with 90 degrees crosswind component up to 30 kt.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A demonstrated crosswind component is just that.  Demonstrated.  It is the highest amount of crosswind that was encountered during the certification process and is put into the AFM as a guide.  It is not a limiting factor though.  This is what the Falcon 50 has in its POH.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Operational Limits&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Operational Limits&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Crosswind&lt;br&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Inoperative engine on lee side: 23 kt.   &lt;/li&gt;&#xA;  &lt;li&gt;Inoperative engine on weather side: 5 kt.   &lt;/li&gt;&#xA;  &lt;li&gt;Center inoperative engine: 23 kt.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case, we have an actual crosswind limitation which can not be legally exceeded.  (Note that in this case this is for a one engine inoperative ferry.)  &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Regulatory Definition&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In the case of the Falcon, it is certified under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=20c044b3eed9d9cb6059d435ced64271&amp;amp;n=14y1.0.1.3.11&amp;amp;r=PART&amp;amp;ty=HTML&quot; rel=&quot;nofollow&quot;&gt;14 CFR Part 25&lt;/a&gt;.  The requirements are similar (but not the same) for Part 23 airplanes.  In particular, we need to look at:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=20c044b3eed9d9cb6059d435ced64271&amp;amp;node=14:1.0.1.3.11.2.160.37&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;§25.237 - Wind velocities.&lt;/a&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) For land planes and amphibians, the following applies:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A 90-degree cross component of wind velocity, demonstrated to be&#xA;  safe for takeoff and landing, must be established for dry runways and&#xA;  must be at least 20 knots or 0.2 VSR0, whichever is greater, except&#xA;  that it need not exceed 25 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The crosswind component for takeoff established without ice&#xA;  accretions is valid in icing conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The landing crosswind component must be established for:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Non-icing conditions, and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Icing conditions with the landing ice accretion defined in&#xA;  appendix C.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For seaplanes and amphibians, the following applies:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A 90-degree cross component of wind velocity, up to which takeoff&#xA;  and landing is safe under all water conditions that may reasonably be&#xA;  expected in normal operation, must be established and must be at least&#xA;  20 knots or 0.2 VSR0, whichever is greater, except that it need not&#xA;  exceed 25 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) A wind velocity, for which taxiing is safe in any direction under&#xA;  all water conditions that may reasonably be expected in normal&#xA;  operation, must be established and must be at least 20 knots or 0.2&#xA;  VSR0, whichever is greater, except that it need not exceed 25 knots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This basically says that they need to test it up to 25 knots.  They can choose to test it higher if they want to, but it isn't required.  If they find that there is a speed less than 25 knots where the airplane isn't &quot;safe&quot;, then they need to impose an actual operating limitation.  Otherwise, they just publish the value that it was tested to for reference and it is not a limiting value.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="679" LastEditDate="2015-01-24T18:47:02.693" LastActivityDate="2015-01-24T18:47:02.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1347" PostTypeId="2" ParentId="939" CreationDate="2014-01-26T06:02:14.697" Score="31" Body="&lt;p&gt;This particular flight was a Boeing 747 flying from YSSY (Sidney) to SCEL (Santiago).  Because a 747 has more than two engines, they don't have specific time limits on how far from land that they can fly like two engine airplanes do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, they do have to carry enough fuel to make it to a suitable airport in the event that the airplane depressurizes or it has an engine failure at any point along their route.&lt;sup&gt;1&lt;/sup&gt;.  This doesn't mean that they have to make it all of the way to their destination in the event of a problem though.  They use en-route diversion airports and have predefined points on their flight plan which tell them where to divert to at any given point during the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice on this flight (see the images below) that their planned route is considerably further North than the shorter great circle route.  This is probably so that they can use NTAA (Tahiti) as a diversion airport if they have a problem.  The route is also optimized for the current winds at the cruising altitude, so it may be more fuel efficient to go out of the way in order to have more favorable winds.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, without seeing their actual dispatch paperwork we can't know for sure whether or not they could have even flown the great circle route with the amount of fuel that the airplane can hold, but we'll just assume that they are using NTAA as an ETOPS airport for the purposes of this discussion.  That being said, we will use the following airports as our ETOPS diversion airports:  NZCH, NTAA, and SCEL.  In this case, their diversion plan in the event of an emergency would probably be something like this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From takeoff (YSSY) until a point a little less than half way to NZCH (New Zealand)&lt;sup&gt;2&lt;/sup&gt; they would divert back to their point of departure&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;From a little less than half way to NZCH until a point around 46W52 they would divert to NZCH.&lt;/li&gt;&#xA;&lt;li&gt;Between the points that would be around 46W52 and 47W25 they would divert to NTAA.&lt;/li&gt;&#xA;&lt;li&gt;After 47W25 they would continue on to their destination (SCEL) because it would be faster than turning around and going back to any of the other airports.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each of the points takes wind into consideration, and as they pass each one they will always know which airport that they can reach in the least amount of time.  The most important thing is that they always have enough fuel to make it &lt;em&gt;somewhere safe&lt;/em&gt; in the event of an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tapZv.png&quot; alt=&quot;QFA27 Filed Route&quot;&gt;&#xA;&lt;em&gt;Filed Route&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j2NI3.png&quot; alt=&quot;Great Circle Route&quot;&gt;&#xA;&lt;em&gt;Great Circle Route&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;em&gt;They also have to carry enough fuel to fly to their alternate airport and additional contingency fuel.  One thing to keep in mind is that a jet burns &lt;strong&gt;considerably&lt;/strong&gt; more fuel at low altitudes than they do at their optimum altitude, so they have to carry a lot of extra fuel to meet this (and other) requirement.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; &lt;em&gt;If they turned around at the exact halfway point, it would take them longer to return than to continue because of the East winds.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Regulations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those of you interested in the actual fuel requirements for a flight like this, the US regulations are listed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=daa0248cbfc27cec50970f7740577020&amp;amp;node=14:3.0.1.1.7&amp;amp;rgn=div5#14:3.0.1.1.7.30.3.2.25&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 121&lt;/a&gt;.  I'll use these as an example (other countries will be very similar, but I know these.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice that almost every line of the regulations listed here will require extra fuel to be on board the airplane. (Look for the ✈ symbol next to each one that I have added.)  Fortunately, it isn't quite as bad as it looks though, because some of the fuel that is pumped into the airplane can be used for more than one purpose.  For instance, a portion of the fuel may be used to divert to an ETOPS airport &lt;strong&gt;and&lt;/strong&gt; used to fly to your destination, because they will only be doing one or the other.  The pertinent regulations are summarized here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=daa0248cbfc27cec50970f7740577020&amp;amp;node=14:3.0.1.1.7&amp;amp;rgn=div5#14:3.0.1.1.7.21.3.30&quot; rel=&quot;noreferrer&quot;&gt;§121.645 - Fuel supply: Turbine-engine powered airplanes...&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For any certificate holder conducting flag or supplemental&#xA;  operations outside the 48 contiguous United States and the District of&#xA;  Columbia, unless authorized by the Administrator in the operations&#xA;  specifications, no person may release for flight or takeoff a&#xA;  turbine-engine powered airplane (other than a turbo-propeller powered&#xA;  airplane) unless, considering wind and other weather conditions&#xA;  expected, it has enough fuel—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (1) To fly to and land at the airport to which it is released;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (2) After that, to fly for a period of 10 percent of the total time&#xA;  required to fly from the airport of departure to, and land at, the&#xA;  airport to which it was released;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (3) After that, to fly to and land at the most distant alternate&#xA;  airport specified in the flight release, if an alternate is required;&#xA;  and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (4) After that, to fly for 30 minutes at holding speed at 1,500 feet&#xA;  above the alternate airport (or the destination airport if no&#xA;  alternate is required) under standard temperature conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=daa0248cbfc27cec50970f7740577020&amp;amp;node=14:3.0.1.1.7&amp;amp;rgn=div5#14:3.0.1.1.7.21.3.31&quot; rel=&quot;noreferrer&quot;&gt;§121.646 - En-route fuel supply: flag and supplemental operations.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may dispatch or release for flight a turbine-engine&#xA;  powered airplane with more than two engines for a flight more than 90&#xA;  minutes (with all engines operating at cruise power) from an Adequate&#xA;  Airport unless the following fuel supply requirements are met:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The airplane has enough fuel to meet the requirements of&#xA;  §121.645(b);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (2) The airplane has enough fuel to fly to the Adequate Airport—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (i) Assuming a rapid decompression at the most critical point;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (ii) Assuming a descent to a safe altitude in compliance with the&#xA;  oxygen supply requirements of §121.333; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (iii) Considering expected wind and other weather conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (3) The airplane has enough fuel to hold for 15 minutes at 1500 feet&#xA;  above field elevation and conduct a normal approach and landing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may dispatch or release for flight an ETOPS flight&#xA;  unless, considering wind and other weather conditions expected, it has&#xA;  the fuel otherwise required by this part and enough fuel to satisfy&#xA;  each of the following requirements:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (1) Fuel to fly to an ETOPS Alternate Airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (i) Fuel to account for rapid decompression and engine failure. The&#xA;  airplane must carry the greater of the following amounts of fuel:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (A) Fuel sufficient to fly to an ETOPS Alternate Airport assuming a&#xA;  rapid decompression at the most critical point followed by descent to&#xA;  a safe altitude in compliance with the oxygen supply requirements of&#xA;  §121.333 of this chapter;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (B) Fuel sufficient to fly to an ETOPS Alternate Airport (at the&#xA;  one-engine-inoperative cruise speed) assuming a rapid decompression&#xA;  and a simultaneous engine failure at the most critical point followed&#xA;  by descent to a safe altitude in compliance with the oxygen&#xA;  requirements of §121.333 of this chapter; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (C) Fuel sufficient to fly to an ETOPS Alternate Airport (at the one&#xA;  engine inoperative cruise speed) assuming an engine failure at the&#xA;  most critical point followed by descent to the one engine inoperative&#xA;  cruise altitude.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (ii) Fuel to account for errors in wind forecasting. In calculating&#xA;  the amount of fuel required by paragraph (b)(1)(i) of this section,&#xA;  the certificate holder must increase the actual forecast wind speed by&#xA;  5% (resulting in an increase in headwind or a decrease in tailwind) to&#xA;  account for any potential errors in wind forecasting. If a certificate&#xA;  holder is not using the actual forecast wind based on a wind model&#xA;  accepted by the FAA, the airplane must carry additional fuel equal to&#xA;  5% of the fuel required for paragraph (b)(1)(i) of this section, as&#xA;  reserve fuel to allow for errors in wind data.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (iii) Fuel to account for icing. In calculating the amount of fuel&#xA;  required by paragraph (b)(1)(i) of this section (after completing the&#xA;  wind calculation in paragraph (b)(1)(ii) of this section), the&#xA;  certificate holder must ensure that the airplane carries the greater&#xA;  of the following amounts of fuel in anticipation of possible icing&#xA;  during the diversion:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (A) Fuel that would be burned as a result of airframe icing during 10&#xA;  percent of the time icing is forecast (including the fuel used by&#xA;  engine and wing anti-ice during this period).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (B) Fuel that would be used for engine anti-ice, and if appropriate&#xA;  wing anti-ice, for the entire time during which icing is forecast.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (iv) Fuel to account for engine deterioration. In calculating the&#xA;  amount of fuel required by paragraph (b)(1)(i) of this section (after&#xA;  completing the wind calculation in paragraph (b)(1)(ii) of this&#xA;  section), the airplane also carries fuel equal to 5% of the fuel&#xA;  specified above, to account for deterioration in cruise fuel burn&#xA;  performance unless the certificate holder has a program to monitor&#xA;  airplane in-service deterioration to cruise fuel burn performance.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (2) Fuel to account for holding, approach, and landing. In addition to&#xA;  the fuel required by paragraph (b)(1) of this section, the airplane&#xA;  must carry fuel sufficient to hold at 1500 feet above field elevation&#xA;  for 15 minutes upon reaching an ETOPS Alternate Airport and then&#xA;  conduct an instrument approach and land.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (3) Fuel to account for APU use. If an APU is a required power source,&#xA;  the certificate holder must account for its fuel consumption during&#xA;  the appropriate phases of flight.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=daa0248cbfc27cec50970f7740577020&amp;amp;node=14:3.0.1.1.7&amp;amp;rgn=div5#14:3.0.1.1.7.21.3.32&quot; rel=&quot;noreferrer&quot;&gt;§121.647 - Factors for computing fuel required.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Each person computing fuel required for the purposes of this subpart&#xA;  shall consider the following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (a) Wind and other weather conditions forecast.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (b) Anticipated traffic delays.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (c) One instrument approach and possible missed approach at&#xA;  destination.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;✈ (d) Any other conditions that may delay landing of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For the purposes of this section, required fuel is in addition to&#xA;  unusable fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-14T18:39:08.060" LastActivityDate="2014-04-14T18:39:08.060" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1348" PostTypeId="2" ParentId="516" CreationDate="2014-01-26T07:43:22.953" Score="23" Body="&lt;p&gt;Since a student pilot posed the query, here are some various thoughts based on my experience with FF. I'm a low-time VFR pilot (500 hours). I rarely make short flights; mostly cc for 1-3 hours.  (I wouldn't typically use FF for a 30-min hop). I consider FF a HUGE privilege that could easily be taken away if enough GA pilots abuse it, neglect it, or don't take it seriously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;strong&gt;&lt;em&gt;always&lt;/em&gt;&lt;/strong&gt; use FF at night.  I highly recommend that.  I do a lot of night flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm flying thru or even near Charlie airspace by day, I use FF near and thru that region.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm flying near or thru Bravo airspace by day, I use FF for the entire flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have &lt;strong&gt;&lt;em&gt;never&lt;/em&gt;&lt;/strong&gt; been refused for FF. Maybe it required a 2nd request a few times, but never refused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make sure your transponder is kept in good working order and calibrated according to your AD once you get your own plane.  If there is an issue with your transponder, FF may ask you to ident, and if they still can't establish a fix on you, they may ask you to recycle your transponder (turn it off, give it 5 seconds, turn it back on, let it re-set.)  &lt;strong&gt;Never do this unless asked or without asking their permission&lt;/strong&gt;.  You drop off their radar completely for several seconds, and if they're not expecting it they'll rightfully freak.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's &lt;strong&gt;&lt;em&gt;very easy&lt;/em&gt;&lt;/strong&gt; to miss a call from FF if you're talking with your passengers.&#xA;I inform my passengers that I'm using FF and I either need to isolate myself or limit discussion.  Most of my passengers love to hear the ATC chatter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't refuse a &quot;request&quot; from a controller unless it creates a safety concern. For example, I've been kindly requested to veer around a busy corridor near Louisville at 11 pm when UPS has taken over the airport.  (Why would I say no?)  Understand if you're not in the corridor or in the airspace, FF will &quot;request&quot; rather than &quot;demand.&quot;  Tell them you'd be happy to.  It will probably cost you 90 seconds. Remember you're the smallest guy they're watching.  Respect that!!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whenever you hear your tail number called, put your right hand on the frequency dial before they say the next word.  Nothing annoys FF more than low time VFR pilots asking two or three times to repeat a frequency when they are handing you off to the next sector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Learn which FF calls MUST be answered and which don't.  You'll probably learn mostly by trial and error, but you can get in far more trouble by saying nothing than by offering a quick, &lt;em&gt;&quot;937 Affirm.&quot;&lt;/em&gt;  When they say, &quot;937, traffic at 10 O'clock, 7,000 feet. No factor.&quot; you don't have to reply ... but why not?  &lt;em&gt;&quot;937 Roger.&quot;&lt;/em&gt;  It's a lot like being reassured that your teenager didn't fall asleep in the middle of a conversation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I never fail to affirm a frequency change on a handoff ... I don't necessarily read back the new frequency ... just &quot;937 Affirm.  G'night.&quot;  If they go looking for you, they have reason to be annoyed.  I've been the &quot;annoyer&quot; before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Always help a controller who is asking you to help find a missing pilot.  They'll love you for it.  (If you ID yourself as a student, they likely won't pick you to ask for help)  That's reason #267 to always keep a pen handy ... a semi-panicking controller who says, &quot;937, can you do me a favor?  Go to 123.475 and see if you can find N654 Mike Papa.  He never terminated radar coverage and we can't find him.&quot;  It happens.  More than you'd think.  Drives the  controllers crazy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;ALWAYS&lt;/em&gt;&lt;/strong&gt; advise on your altitude changes.  They'll usually say, &quot;Maintain VFR and advise of any altitude changes.&quot;  Again, it will drive them nuts if you start a descent without advising.  When you advise, they will always verify and usually thank you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're using an intermediate waypoint such as an airport or VOR, let FF know it if it's far enough off of a direct route to your destination airport that it could cause some confusion.  04º ... don't bother.  25º ... bother.  Same goes for deviating around weather.  Chances are they'll let you know of the approaching weather before you see it, but do all you can to make their job easy.  Beat 'em to the punch and they'll appreciate it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once I'm within 15 miles or so of my destination airport, I often get the feeling that FF is reeeeally wishing I'd terminate radar so they can get rid of me ... but since a lot of confusion and bad things can happen on approach, don't terminate FF earlier than you feel comfortable.  They'll want you to tell them you have the weather and the field in sight when you terminate.  Whether it's legal, proper, assumed, or otherwise, when you advise, &quot;Indy Service, N937 has the Indy Metro weather and field in sight&quot; they will immediately respond with their &quot;termination&quot; spiel.  By day, I typically do this 8-10 miles out.  By night, especially with any weather, rarely before 5-6 miles out. When you start flying RNAV/GPS or ILS approaches, that's usually the intermediate approach fix.&lt;/p&gt;&#xA;" OwnerUserId="699" LastEditorUserId="699" LastEditDate="2014-01-26T07:50:33.107" LastActivityDate="2014-01-26T07:50:33.107" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1349" PostTypeId="1" AcceptedAnswerId="1350" CreationDate="2014-01-26T07:49:19.853" Score="13" ViewCount="4966" Body="&lt;p&gt;What steps should I take after failing the oral portion of the check ride for my PPL?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="62" LastEditDate="2014-01-26T16:13:27.963" LastActivityDate="2014-01-27T04:46:06.673" Title="What should I do after failing the oral portion of my private pilot check ride?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1350" PostTypeId="2" ParentId="1349" CreationDate="2014-01-26T08:15:18.567" Score="13" Body="&lt;p&gt;AOPA has a &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2013/November/feature-deal.html&quot; rel=&quot;nofollow&quot;&gt;great article&lt;/a&gt; about this, and it basically says:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Since you failed the oral, more studying is probably in order.&lt;/li&gt;&#xA;&lt;li&gt;You will need to receive training in the area(s) of the checkride that you failed from a flight instructor.&lt;/li&gt;&#xA;&lt;li&gt;Once the flight instructor feels that you are proficient and able to pass the checkride, they will sign your logbook so that you may take it again.&lt;/li&gt;&#xA;&lt;li&gt;Schedule your checkride again.  If you take it within 60 days, you will only need to test on the areas that you failed.  After 60 days you have to take the entire checkride over again.&lt;/li&gt;&#xA;&lt;li&gt;Take your Notice of Disapproval (8060-5) with you to the checkride (you didn't burn it did you??)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Like the article says, it isn't the end of the world!  About 20% of first time applicants fail their checkride, but all you have to do is use it as a learning experience and let it make you an even better pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have questions about specific subjects, you can also ask questions here and we will be happy to help you out!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-01-27T04:46:06.673" LastActivityDate="2014-01-27T04:46:06.673" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1351" PostTypeId="2" ParentId="1349" CreationDate="2014-01-26T08:23:41.823" Score="13" Body="&lt;p&gt;Keegan, I understand you may not want to specify where you had difficulty, but without knowing that, I'm afraid it's going to be difficult for anyone to help direct you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me throw out two thoughts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) If you failed on regulatory questions, that is a lot like studying for a spelling bee.  Reading, retention, and repetition is hard work, but required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) If you failed on the &quot;what if&quot; questions, I have a feeling you have even more work to do.  I think the &quot;what if&quot; questions are what separates the great pilots from the pilots I'd refuse to fly with.  &quot;What if&quot; you lose your engine over this spot at 7,500 feet MSL with the winds aloft 160º at 30 knots at 6,000 and 180º at 45 knots at 9,000?  If you didn't know instinctively at every moment of your flight where you would put the aircraft down using your GPS nearest feature, your flight plan (filed or not), your engine out training, and your common sense, then you're going to have a little more difficult time convincing the DPE who failed you to give you another chance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm absolutely not trying to scare you off of flying, but I've only got 500 hours and I've already been through a failed alternator at night and a nearly engine out landing by day (diminished power leading to a deviation and unscheduled &quot;idled&quot; landing) and it only takes once to know for certain whether you can pull these off with your training and good common sense, or panic and declare an emergency unnecessarily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you'd like to post a few examples of questions that gave you trouble, I know everyone who browses this forum will be helpful.&lt;/p&gt;&#xA;" OwnerUserId="699" LastActivityDate="2014-01-26T08:23:41.823" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1352" PostTypeId="1" AcceptedAnswerId="1354" CreationDate="2014-01-26T12:02:08.283" Score="10" ViewCount="4330" Body="&lt;p&gt;Some airplanes like the B-52 or the MU-2 use spoilerons instead of ailerons to control roll. What is the benefit of ailerons vs spoilerons and vice versa?&lt;/p&gt;&#xA;" OwnerUserId="163" LastEditorUserId="69" LastEditDate="2014-01-26T14:32:36.637" LastActivityDate="2014-01-27T05:25:12.543" Title="What is the benefit of spoilerons compared to ailerons?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1353" PostTypeId="2" ParentId="634" CreationDate="2014-01-26T12:12:22.943" Score="1" Body="&lt;p&gt;My CFI instructed me to present my Pilot's License for the inspector to view (only if asked) but never to hand it to him ... because that is interpreted by the FAA as &quot;voluntarily surrendering&quot; one's license ... in which case he may keep it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have nothing to back that up, but this is an instructor with 3500 hours and serves as an airport chairman, so I tend to believe he knows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same person tells me that the most common reason for random ramp checks is to find private pilots flying what can be determined by the FAA to be flights for compensation of some kind.  AOPA had an article about a month ago about the ambiguity of this regulation.  The FAA's definition of &quot;compensation&quot; seems to be so far reaching it is undefinable.  If, for example, I fly a friend to a college football game and he later helps me get a better paying job, the FAA seems to be saying that they can determine that I received an indirect benefit (compensation) as a result of our joy ride.  Laughable.&lt;/p&gt;&#xA;" OwnerUserId="699" LastEditorUserId="699" LastEditDate="2014-01-26T12:17:25.557" LastActivityDate="2014-01-26T12:17:25.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1354" PostTypeId="2" ParentId="1352" CreationDate="2014-01-26T14:42:42.770" Score="12" Body="&lt;p&gt;Two reasons often-cited for having spoilerons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;better roll control (especially during stall)&lt;/li&gt;&#xA;&lt;li&gt;doesn't take up space for flaps&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Because of their location, they don't need to take up space which could be used for flaps. For example, on the MU-2, the primary reason for using spoilerons was to allow for full-span flaps at the rear, lowering clean wing area while still having acceptable stall speeds in the takeoff/landing configurations (and therefore shorter landing distances). This is one of the reasons for it to takeoff from runways less than 3000 feet, while having a cruise speed of up to 300 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, spoilerons have the disadvantage of killing lift, which can be deadly in situations such as a one-engine-out situation in a twin. To compensate for this, usually minimal constant spoiler use is recommended, and mostly rudder is used if an engine fails. If available, aileron trim (despite the name, there aren't any &quot;real&quot; ailerons on such an aircraft) is used to reduce drag if long-term use is expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilerons tend to have less of a difference in roll rates at low and high speeds, compared to ailerons -- this could either be considered an advantage or a disadvantage, depending on the situation and whether a pilot is used to one type of roll control or another. This can negatively affect the roll control feel of the aircraft though, as it might feel slightly sluggish at higher airspeeds. They also tend not to provide much (if any) feedback to the pilot, which is a disadvantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that most large airliners use both spoilerons and ailerons for roll control, to be able to still have an aileron while supplementing large control inputs with the spoilers.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-27T05:25:12.543" LastActivityDate="2014-01-27T05:25:12.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1355" PostTypeId="2" ParentId="1320" CreationDate="2014-01-26T18:06:54.407" Score="7" Body="&lt;p&gt;Call an AME. They'll answer your questions more definitively and then you'll have an official opinion. AOPA's database is good but it is &lt;strong&gt;not&lt;/strong&gt; official and probably wouldn't hold up as a defense if you somehow got in trouble for using some medication that you thought was okay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, an AME can refer you to alternative medications that might be approved. For example, Cetirizine (Zyrtec etc.) is banned because it causes drowsiness and blurred vision, but Loratadine (Claritin etc.) is acceptable. Perfectly viable substitute for some people with allergies (not me, unfortunately) but you'd never know it looking at AOPA's list (although I think AMAS talks about alternatives).&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-01-27T04:32:14.260" LastActivityDate="2014-01-27T04:32:14.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1356" PostTypeId="5" CreationDate="2014-01-27T02:18:50.527" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-01-27T02:18:50.527" LastActivityDate="2014-01-27T02:18:50.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1357" PostTypeId="4" CreationDate="2014-01-27T02:18:50.527" Score="0" Body="NOTAMs (Notices To Airmen) are important notices to let pilots know of changed conditions or restrictions that are likely to affect the ability of pilots to conduct normal operations." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-01-27T02:27:34.003" LastActivityDate="2014-01-27T02:27:34.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1358" PostTypeId="2" ParentId="1352" CreationDate="2014-01-27T02:53:43.550" Score="7" Body="&lt;p&gt;Aside from freeing up trailing edge space for flaps, spoilerons induce no adverse yaw when they are deflected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ailerons can cause a yawing moment opposite the roll direction leading to uncoordinated flight; spoilerons, because they only deploy on the low wing, can in some installations result in proverse yaw that can serve to reduce the need for rudder coordination. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-27T02:53:43.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1359" PostTypeId="2" ParentId="164" CreationDate="2014-01-27T09:26:57.170" Score="-2" Body="&lt;p&gt;Say you have trimmed an Aircraft than forces on aircraft i.e Lift == Weight &amp;amp; Thrust == Drag. So aircraft is flying (straight and level) or climbing or descending at constant speed or rate(of climb or descend).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simple to remmember, Trimmed Aircraft means Lift = Weight and Thrust = Drag thats it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lot of way to trim an aircraft: Trim Tabs on control surface, complete surface moves to trim corresponding control surface (ex: stabilizer moves in response to pitch trim command) etc.&lt;/p&gt;&#xA;" OwnerUserId="685" LastActivityDate="2014-01-27T09:26:57.170" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1360" PostTypeId="2" ParentId="497" CreationDate="2014-01-27T09:39:37.120" Score="3" Body="&lt;p&gt;This is not only an Autopilot-specific question but also a design-specific question, which will be different based on the OEM (Original Equipment Manufacturer) and the Aircraft Specification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually in modern aircraft, the Autopilot sends commands to Flight Control System which then sends commands to Actuators and this progression of commands happens at different rates. This update rate could be, for example, 100 Hz (10 ms), 80 Hz (12.5 ms) or may be even slower or faster, depending on the flight control system of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the command is not sent per second or minute, but rather 100's of commands per second, because commands to move the control surface are the most critical commands on an aircraft.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="97" LastEditDate="2014-04-16T23:41:23.027" LastActivityDate="2014-04-16T23:41:23.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1361" PostTypeId="1" CreationDate="2014-01-27T14:33:10.730" Score="18" ViewCount="21318" Body="&lt;p&gt;If you are flying VFR into deterioration weather conditions and would like to continue the flight under IFR, or you would like to climb to a better altitude but are restricted by a cloud layer, what is the easiest way to go about requesting and instrument clearance.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="62" LastEditDate="2018-02-25T05:07:24.523" LastActivityDate="2021-05-18T18:22:01.650" Title="How do you request a &quot;pop up&quot; IFR clearance?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;clearance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1362" PostTypeId="2" ParentId="1361" CreationDate="2014-01-27T15:09:46.377" Score="14" Body="&lt;p&gt;Assuming you are not already talking to ATC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You: &lt;code&gt;Houston Center, Cessna 1234X, request&lt;/code&gt;*&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Center: &lt;code&gt;Cessna 34X, Houston Center, go ahead&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You: &lt;code&gt;Cessna 34X is a 172/U, 35 North IDU, 4500 ft, request IFR to Austin&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Center: &lt;code&gt;Cessna 34X ident, fly heading 270&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Center: &lt;code&gt;Cessna 34X is cleared to AUS via radar vectors, climb and maintain 6000 ft, squawk 5634&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is essentially the same as making a request for VFR flight following services with the exceptions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Your aircraft needs to be legal for IFR.&lt;/li&gt;&#xA;&lt;li&gt;You need to be rated and current for IFR.&lt;/li&gt;&#xA;&lt;li&gt;You will receive a clearance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you already have flight following and need IFR, the controller has you on his scope and already has a strip for you, and you just need to ask him to make you IFR.  In that case he will just put you on an IFR altitude and give you a clearance limit and route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*&lt;sub&gt;As noted in the comments, you may decorate this call with something identifying the nature of your request&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-27T15:36:04.827" LastActivityDate="2014-01-27T15:36:04.827" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1363" PostTypeId="1" AcceptedAnswerId="1370" CreationDate="2014-01-27T15:49:01.040" Score="20" ViewCount="31945" Body="&lt;p&gt;For a Private Pilot License in USA, what happens when a student takes his/her checkride? I want to know the sequence of events. According to my knowledge, which is sort of vague, things proceed as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Student takes an oral and written exam (not sure if it's on the same day of checkride or prior to that).&lt;/li&gt;&#xA;&lt;li&gt;Examiner asks student to plan a cross-country flight.&lt;/li&gt;&#xA;&lt;li&gt;Examiner and students go for this planned cross-country flight.&lt;/li&gt;&#xA;&lt;li&gt;Examiner may or may not cancel this plan and ask student to go back (does not affect result).&lt;/li&gt;&#xA;&lt;li&gt;At the end, examiner tells the student if he/she has passed or not.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;What I do not know is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How much of the above is accurate?&lt;/li&gt;&#xA;&lt;li&gt;And how long does it take?&lt;/li&gt;&#xA;&lt;li&gt;How are emergency procedures created and tested?&lt;/li&gt;&#xA;&lt;li&gt;Who makes sure that the weather is suitable for flying?&lt;/li&gt;&#xA;&lt;li&gt;What if the checkride has to be cancelled for reasons not controlled by student?&lt;/li&gt;&#xA;&lt;li&gt;What else did I miss?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2016-03-11T00:38:01.443" LastActivityDate="2016-03-11T14:09:21.290" Title="What happens during a checkride for a private pilot license?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;ppl&gt;&lt;checkride&gt;&lt;designated-examiner&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1364" PostTypeId="1" AcceptedAnswerId="1366" CreationDate="2014-01-27T15:58:35.247" Score="18" ViewCount="4295" Body="&lt;p&gt;A &quot;Sterile Cockpit&quot; means avoiding all conversations and actions not related to flight during important flight times.  &lt;em&gt;(eg. No extraneous conversations, no non-important electronics, no eating, etc)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial pilots are told to observe Sterile Cockpit below 10,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what about Private Pilots who may rarely ever go above 10,000?  When do you begin observing sterile cockpit?  When do you consider it safe to talk with passengers, take a snack, or fiddle with the new GPS?&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-01-27T16:31:35.980" Title="When should pilots observe a &quot;Sterile Cockpit&quot;?" Tags="&lt;safety&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1365" PostTypeId="2" ParentId="1363" CreationDate="2014-01-27T16:13:23.863" Score="13" Body="&lt;p&gt;You will be examined in 3 ways, &lt;code&gt;written&lt;/code&gt;, &lt;code&gt;oral&lt;/code&gt; and &lt;code&gt;practical&lt;/code&gt;.  The &lt;code&gt;checkride&lt;/code&gt; consists of only the &lt;code&gt;oral&lt;/code&gt; and &lt;code&gt;practical&lt;/code&gt; portions of the exams.  The &lt;code&gt;written&lt;/code&gt; is computer based and must have been completed with the 2 years preceding the &lt;code&gt;checkride&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you complete the written you will get a sheet that is stamped and embossed certifying your score and listing your deficient areas.  You will present this to the &lt;code&gt;designated examiner&lt;/code&gt; (DE) that conducts your checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When your instructor recommends you for the checkride, he (or you) will coordinate with the DE and tell you to prepare a cross country flight plan (complete with winds/times/fuel burn for the day of the exam).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you arrive at the checkride, the DE will being querying your knowledge about the airplane, its limitations, v-speeds, equipment, legality for VFR day/night flight, etc.  He will also query your knowledge on flight planning, weather, airworthiness, navigation, regulations, etc.  The topics of interest are all listed in the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot;&gt;Practical Test Standards (PTS)&lt;/a&gt; area of operation I.  These questions comprise the oral examination.  This can take anywhere from 1 - 3 hours, depending on numerous factors (your performance, your deficiencies on the written, what checkride this is (initial vs addon vs instructor), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the airworthiness questioning will involve the aircraft logbooks and verifying the airplane is legal for the flight you are about to embark on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the practical part of the exam, the DE is going to observe and make notes and give the occasional command or question.  He is not going to coach you.  If he touches the controls, you will get the pink slip.  From the go/no-go decision to the end of flight, &lt;strong&gt;you are the PIC&lt;/strong&gt; and you must demonstrate the ability to perform as one.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will preflight and perform some variety of takeoff at the DEs discretion and then proceed on your cross country flight.  At some point along this flight you will find the need to divert and will be tested knowing how to calculate time/fuel burn to your new destination based on your present position, as well as properly turning to a heading that will get you there.  Along the way you will do maneuvers.  When you get there you will do some landings and takeoffs.  On the way back home, you will do maneuvers.   The list of maneuvers and how well you need to fly them are in the same PTS document linked above.  This flight will probably be around 2.0 on the hobbes clock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If at anytime you &quot;bust&quot; the checkride, the DE should tell you immediately and give you the option to go home or continue.  It is in your interest to continue if your nerves haven't got the better of you as if you re-take the exam within 60 days you do not have to repeat successful items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you park the plane the DE will go inside while you do the post-flight and when you get inside he will either have a temporary certificate or a pink slip.  If you get the certificate, you are a private pilot.  If you get the pink slip, you get some more instruction and try again.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-01-27T16:33:05.040" LastActivityDate="2014-01-27T16:33:05.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1366" PostTypeId="2" ParentId="1364" CreationDate="2014-01-27T16:17:45.573" Score="15" Body="&lt;p&gt;The &quot;sterile cockpit rule&quot; is an informal name for &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b20a1f7322bceeea9fb5b78ed1f9499b&amp;amp;node=14:3.0.1.1.7.20.3.8&amp;amp;rgn=div8&quot;&gt;14 CFR 121.542&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e56b27b02662af952e2ccf7aa12f765c&amp;amp;node=14:3.0.1.1.11.2.3.25&amp;amp;rgn=div8&quot;&gt;14 CFR 135.100&lt;/a&gt;.  It says that no non-essential duties may be done during a &lt;strong&gt;critical phase of flight&lt;/strong&gt; which is defined as &quot;&lt;em&gt;all ground operations involving taxi, takeoff and landing, and all other flight operations conducted below 10,000 feet, &lt;strong&gt;except cruise flight&lt;/strong&gt;&quot;.&lt;/em&gt;  In your example, once they level off at cruise, even if it is below 10,000 feet, it no longer applies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this doesn't apply to Part 91 operations like you describe, it is a very good idea to follow the rule anyway to prevent distractions and increase the level of safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the GPS, I would recommend fiddling with it on the ground before you takeoff and be familiar with its operation before you need to use it.  Being heads down for an extended period of time is never a good idea (unless you have a safety pilot along to keep an eye on things and look for traffic)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full text of the regulation is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§121.542   Flight crewmember duties.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No certificate holder shall require, nor may any flight crewmember&#xA;  perform, any duties during a critical phase of flight except those&#xA;  duties required for the safe operation of the aircraft. Duties such as&#xA;  company required calls made for such nonsafety related purposes as&#xA;  ordering galley supplies and confirming passenger connections,&#xA;  announcements made to passengers promoting the air carrier or pointing&#xA;  out sights of interest, and filling out company payroll and related&#xA;  records are not required for the safe operation of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No flight crewmember may engage in, nor may any pilot in command&#xA;  permit, any activity during a critical phase of flight which could&#xA;  distract any flight crewmember from the performance of his or her&#xA;  duties or which could interfere in any way with the proper conduct of&#xA;  those duties. Activities such as eating meals, engaging in&#xA;  nonessential conversations within the cockpit and nonessential&#xA;  communications between the cabin and cockpit crews, and reading&#xA;  publications not related to the proper conduct of the flight are not&#xA;  required for the safe operation of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) For the purposes of this section, critical phases of flight&#xA;  includes all ground operations involving taxi, takeoff and landing,&#xA;  and all other flight operations conducted below 10,000 feet, except&#xA;  cruise flight.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note: Taxi is defined as “movement of an airplane under its own power&#xA;  on the surface of an airport.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;NASA has a great article called &lt;a href=&quot;http://asrs.arc.nasa.gov/publications/directline/dl4_sterile.htm&quot;&gt;The Sterile Cockpit&lt;/a&gt; which goes into a &lt;strong&gt;lot&lt;/strong&gt; more information, and includes some interesting statistics from the ASRS database about accidents/incidents that were in some way caused by not following this regulation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;48% were altitude deviations&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;14% were course deviations&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;14% were runway transgressions&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;14% were general distractions with no specific adverse consequences&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;8% involved takeoffs or landings without clearance&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2% involved near mid-air collisions due to inattention and&#xA;  distractions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Abiding by the sterile cockpit rule can help you to avoid situations like that! The article also gives some examples from the database and talks about a couple of crashes that were attributed to lack of compliance.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-27T16:31:35.980" LastActivityDate="2014-01-27T16:31:35.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1367" PostTypeId="2" ParentId="1363" CreationDate="2014-01-27T16:20:09.633" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How much of the above is accurate?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You take the written exam before you take the checkride. When you pass the written, the proctor will give you a piece of paper that proves you passed, you need to show that to the DPE before the checkride. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my case, when I called the DPE to schedule the checkride, he asked me to plan a cross country flight to an airport we both agreed upon. The examiner will review your planning and preflight preparation for the flight but you won't be landing at your destination. Depending on your examiner, he may ask you to divert or simply proceed with other requirements of the test.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And how long does it take?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That depends on the examiner. I believe an hour for the oral and two for the practical flight is common.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How emergency procedures are created and tested?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You should look through the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot;&gt;Practical Test Standards book&lt;/a&gt; to understand what will be required of you. Expect a simulated engine failure, steep turns, power off and power on stalls, slow flight, etc.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Who makes sure that the weather is suitable for flying?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You do, your examiner will be deferring to your judgement about all aspects of the flight. Weather, aircraft airworthiness, your comfort level, etc. He's looking to see if you'll be a safe pilot and make good decisions about flying. If you don't like the weather then reschedule the checkride.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What if checkride has to be cancelled for reasons not controlled by student?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then you'll reschedule with the examiner. I've heard of people having to reschedule four or five times before they actually flew the practical test.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What else did I miss?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know it's easier said than done but: relax! Treat the checkride less as a test and more as your first flight with a passenger. The examiner wants you to pass but they also want to make sure you'll be a safe pilot. Go up with your CFI as many times as needed to feel comfortable and then go up with another CFI in a mock checkride.&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="81" LastEditDate="2014-01-27T16:33:02.007" LastActivityDate="2014-01-27T16:33:02.007" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1368" PostTypeId="1" AcceptedAnswerId="1371" CreationDate="2014-01-27T16:56:27.640" Score="8" ViewCount="2014" Body="&lt;p&gt;In class D and E airspace, there is no separation between IFR and VFR traffic. However, most airspace in the United States below 18,500 feet MSL is class E airspace, which is exactly where non-pressurized aircraft cruise when flying IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is not about regulation (that's perfectly clear: no separation between IFR/VFR) but I'm curious to learn how safe it actually is when cruising at 10,000 feet in VMC on an IFR flight plan while in class E airspace. I'm pretty sure many pilots will be on autopilot without taking too much notice of what's happening outside but according to the regulations the pilot is still responsible for seeing and avoiding other VFR traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any accident statistics on this? I have read hundreds of accident reports over the last few years and I can't remember ever seeing a report on a midair collision between IFR and VFR aircraft in class E.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="72" LastEditDate="2014-03-03T05:30:27.060" LastActivityDate="2018-06-13T11:48:14.247" Title="How safe is IFR in class E?" Tags="&lt;airspace&gt;&lt;visual-flight-rules&gt;&lt;instrument-flight-rules&gt;&lt;class-e-airspace&gt;&lt;separation&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1369" PostTypeId="2" ParentId="1368" CreationDate="2014-01-27T17:14:56.967" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm pretty sure 99% of pilots will be on autopilot without taking too much notice of what's happening outside but according to the regulations the pilot is still responsible for seeing and avoiding other VFR traffic.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, shame on the pilots, then.  Put down your iPads and do your job.  It is &quot;see and avoid&quot;.  Perhaps they have some automation in the cockpit to help them like TIS or TCAS etc. but it is their responsibility to avoid a collision - period.  And the old Mark I eyeball is frequently the only way to accomplish that task.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question more directly, the system works pretty well.  I don't have statistics but I do know that we would read a lot about it in the press if collisions happened regularly.    &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-27T17:14:56.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1370" PostTypeId="2" ParentId="1363" CreationDate="2014-01-27T17:15:41.730" Score="29" Body="&lt;p&gt;That's pretty much the checkride in a nutshell - for all the details on what's expected you should refer to the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/&quot; rel=&quot;noreferrer&quot;&gt;FAA Practical Test Standards&lt;/a&gt; for the rating you're pursuing.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Before your checkride&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;At some point before your checkride you must take a &quot;knowledge test&quot; (the &quot;written exam&quot;) - you must pass that exam in order to qualify to take the checkride (the &quot;practical test&quot;).&lt;br&gt;&#xA;The results of the knowledge test are good for 2 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also receive instruction from your CFI specifically for &quot;checkride preparation&quot; (you must have 3 hours of this instruction within the 60 days prior to taking your checkride).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually your instructor or school will arrange for an examiner. Be sure to find out where he wants you to plan your cross-country trip to, and also ask for his weight (so you can do the weight and balance calculations), and the cost of the checkride (so you can have the money ready).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;The Oral Exam&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The day of your checkride&lt;sup&gt;1&lt;/sup&gt; you'll probably spend at least as much time on the ground with the examiner than in the air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll start with the practicalities: making sure your &lt;a href=&quot;http://www.faa.gov/forms/index.cfm/go/document.information/documentid/185868&quot; rel=&quot;noreferrer&quot;&gt;8710&lt;/a&gt; is in order, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1199/what-are-the-requirements-to-take-the-private-pilot-check-ride&quot;&gt;verifying your eligibility&lt;/a&gt;, and paying the examiner. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, you'll go over your logbook with the examiner (do everyone a favor and bookmark all the things they'll need to see), and then you'll be given &lt;a href=&quot;http://www.youtube.com/watch?v=kr483zBbQKw&quot; rel=&quot;noreferrer&quot;&gt;a thorough oral grilling&lt;/a&gt;&lt;sup&gt;2&lt;/sup&gt; by the examiner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll be expected to know your aircraft's V speeds, it's useful load, and its fuel capacity (in gallons and hours), and you might have to be able to answer intelligently based on a scenario, like &quot;supposed you want to take 3 members of your football team's lineup on a 300 mile trip...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will also be scenario-based regulatory questions (&quot;You're taking your friends for a flight in the spring, but you haven't been in an airplane all winter. What do you need in order to be able to conduct this flight?&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also be expected to plan (or have planned, depending on the examiner&lt;sup&gt;3&lt;/sup&gt;) a cross-country flight (including a weight and balance calculation using the examiner's weight, and possibly including one or more fuel stops), and be able to explain your decision-making process for things like the planned course (if you don't fly in an absolute straight line) and your proposed altitude(s) and en-route waypoint(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; - Usually you do the oral exam, then go fly.  Sometimes you may do the oral one day and the flight portion another day - for example if the weather is lousy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; - This video is a little old, but a lot of it is still valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt; - You used to have to complete the flight plan the day of the exam, within 30 minutes, but that requirement has vanished from the PTS. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;The Flight Exam&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Every examiner conducts this a little differently - the tasks can be done in any order as long as they're all accomplished - but everyone I know has had the same basic sequence of events on their checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the oral you're going to get an update to your weather briefing (because you should), do a preflight inspection, get in the plane, and go fly your cross-country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never met anyone who has actually flown the whole cross-country flight -- The examiner will typically have you fly through one or two waypoints to demonstrate that you can actually navigate, then you'll be told that something has gone awry and you need to divert (&quot;The guy in the back is sick, take me to the closest airport before he hurls.&quot;).&lt;br&gt;&#xA;When you've demonstrated your ability to navigate and divert, you'll usually cancel your flight plan (if you opened one) and break off to do the required air work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point during your checkride the examiner will give you an engine failure, because aircraft engines are supremely unreliable whenever an examiner or CFI is in the right seat. You will be expected to pick a suitable landing point, establish a glide to that landing point, and run the &quot;engine failure&quot; checklist appropriate to your plane.  The engine usually &quot;miraculously restarts&quot; at some point once the examiner is confident you would have been able to put the plane down on your intended landing spot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air-work consists of all the require flight maneuvers, such as steep turns, stalls, slips, and slow flight, the required ground reference maneuvers, and basic instrument maneuvers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the air work is complete you'll return to the airport (or maybe to the airport you diverted to) for the dog-and-pony-show landings (one go-around -- usually called by the examiner with something exciting like &quot;There's a moose on the runway! Go around!&quot;, one normal landing, one short-field landing over an FAA-Standard 50-foot giraffe, and one soft-field landing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you mess up and the examiner has to fail you they will tell you immediately after finishing the maneuver that you busted on. You &lt;em&gt;usually&lt;/em&gt; have the option of continuing the test and completing the remaining tasks unless you did something that made the examiner fear for his or her life (if you're comfortable continuing this reduces the number of tasks you'll have to complete when you re-take the checkride).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you don't screw any thing up too badly, scare the examiner, or hit anything taxiing back to the ramp you're a private pilot - the examiner will fill out the appropriate paperwork, sign your logbook, and issue you your temporary certificate.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Your specific questions that I didn't answer above&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How long does it take?&lt;/strong&gt;&lt;br&gt;&#xA;My checkride took about 3-4 hours -- about 1-2 hours for the logbook review &amp;amp; oral, just over an hour in the plane, and about an hour of &quot;miscellaneous bits&quot; (re-briefing the weather, the preflight, securing the plane after the practical portion of the test, completing the IACRA paperwork to make your new certificate/rating official).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How are emergencies created/tested?&lt;/strong&gt;&lt;br&gt;&#xA;The standard engine failure is usually created by pulling the throttle back. Your examiner may throw other curve balls at you (like handing you the foggles and saying &quot;You just flew into a cloud, get us out of it.&quot;), or create random distractions (&quot;dropping&quot; their pen during climb-out appears to be a favorite from reading other people's checkride stories).&lt;br&gt;&#xA;What's important isn't how the situations arise, but how you handle them.  The examiner wants to see you fly the airplane safely, run the appropriate checklist(s), and handle the emergency in such a way that they're confident if it happened for real you'd be able to do the right thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Who makes sure the weather is suitable for flying?&lt;/strong&gt;&lt;br&gt;&#xA;&lt;em&gt;You do!&lt;/em&gt; You are acting as Pilot In Command for your checkride, and you are expected to exercise sound judgment.&lt;br&gt;&#xA;The examiner is not going to let you take off into a thunderstorm or gale-force winds (examiners have excellent self-preservation instincts. Most of them are or were flight instructors.), but if the &lt;em&gt;examiner&lt;/em&gt; has to be the one to say &quot;Yeah, I don't think we should fly in this weather&quot; that's a guaranteed failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What if the checkride has to be cancelled for reasons not controlled by the student?&lt;/strong&gt;&lt;br&gt;&#xA;If you've already started (e.g. taken the oral, but can't do the flight portion because of weather, or the plane develops a mechanical problem) you'll receive a &quot;notice of discontinuance&quot; and reschedule the remainder of the exam.&lt;br&gt;&#xA;Typically you can do this within 60 days, and you'll only have to do the portions of the exam you didn't do previously (though you can be re-tested on everything).&lt;br&gt;&#xA;The same thing happens if you or the examiner have to cancel the exam for reasons not related to your aeronautical performance (that triple-breakfast-burrito on checkride day was &lt;em&gt;NOT&lt;/em&gt; a good idea and you need to get back on the ground &lt;em&gt;RIGHT NOW&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What else did I miss?&lt;/strong&gt;&lt;br&gt;&#xA;Probably a lot. I probably missed a lot too.&lt;br&gt;&#xA;My checkride wasn't that long ago but I really don't remember much about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A common misconception is that the DE will bust you for one deviation or one wrong answer on the oral. That's simply not true. You must perform at an &quot;acceptable level of competence,&quot; and only if you fail to perform at such a level will you be failed. The best way to avoid this is to acknowledge the deviation by saying something like &quot;I'm low, correcting,&quot; and then correct. That way the DE knows you know what is happening in the plane, and that you are taking positive steps to correct it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, don't think the DE can read your mind. Brief out loud everything that is happening in the plane: annunciate the checklist items, and say &quot;takeoff checklist complete&quot; when you're done; when you scan for traffic or make a clearing turn, say &quot;clearing&quot;; if you see a plane say something like &quot;traffic, 4 o'clock low, opposite direction, no factor.&quot; The more you say, the more the DE knows how you think, and aeronautical decision-making is one of the most important skills a pilot must learn.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-12-18T20:50:23.093" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1371" PostTypeId="2" ParentId="1368" CreationDate="2014-01-27T18:30:57.863" Score="9" Body="&lt;p&gt;As with any flight, &quot;It's as safe as you make it&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vast majority of the General Aviation fleet (piston singles) don't even &lt;em&gt;have&lt;/em&gt; an autopilot, and the ones that do may only be single-axis units (wing levelers), so the pilot has to have some level of attention on flying the airplane.&lt;br&gt;&#xA;If we assume these are the folks flying around VFR we can also generally assume they &lt;em&gt;should&lt;/em&gt; be looking out the window the vast majority of the time (like Skip said, &lt;a href=&quot;https://aviation.stackexchange.com/a/1369/64&quot;&gt;&quot;Put down your iPads and do your job.&quot;&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding to that, &quot;See and avoid&quot; is every pilot's responsibility in VMC - whether operating under Visual Flight Rules or Instrument Flight Rules - if you can see, you are expected to avoid (and if necessary deal with ATC freaking out about you deviating from a clearance later).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A number of other steps have been taken to enhance safety in Class D and E airspace:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.2.5.35&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.159&lt;/a&gt; prescribes specific VFR cruising altitudes, and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.2.6.44&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.179&lt;/a&gt; is the IFR equivalent.&lt;br&gt;&#xA;The cruising altitudes in these regulations result in an automatic 500-foot vertical separation of VFR and IFR traffic (at least between 3,000 feet MSL and 18,000 feet MSL - which is where VFR and IFR traffic are likely to be mixing in cruise. ).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally IFR traffic is &lt;em&gt;usually&lt;/em&gt; receiving radar separation services (there are some non-radar areas in the US, but not many). Nominally this separation is &quot;IFR-to-IFR&quot; in Class E airspace, but if a controller sees a VFR target squawking 1200 and behaving unpredictably they can vector IFR traffic around it.&lt;br&gt;&#xA;Similarly if a controller sees a &quot;primary target only&quot; (something without a transponder, and not reporting altitude information) they will often vector IFR traffic around it until they can establish what it is and what it's doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Within class D airspace the level of service you'll get depends somewhat on the equipment the controllers have.  A &quot;purely visual&quot; tower with no radar can only give traffic advisories for aircraft they can see by looking out their window, but if they see a conflict they're going to say something. A tower with radar (either local or slaved from a nearby airport) may give VFR-to-VFR or VFR-to-IFR separation advisories based on that data as well, sometimes including advisories to aircraft inbound who are outside their airspace.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="10076" LastEditDate="2018-06-13T11:48:14.247" LastActivityDate="2018-06-13T11:48:14.247" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1372" PostTypeId="1" AcceptedAnswerId="1373" CreationDate="2014-01-27T18:58:57.027" Score="-1" ViewCount="14694" Body="&lt;p&gt;This question aims to serve as a &lt;a href=&quot;https://meta.stackexchange.com/questions/11740/what-are-community-wiki-posts&quot;&gt;Community Wiki&lt;/a&gt; resource.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Feel free to edit the list of aviation-related TV shows below!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/1375/what-aviation-related-movies-are-there/1376&quot;&gt;What aviation-related movies are there?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-04-20T22:49:01.680" Title="What aviation-related TV shows are there?" Tags="&lt;airport&gt;&lt;accidents&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="4" ClosedDate="2014-02-03T00:39:43.113" ContentLicense="CC BY-SA 3.0" />
  <row Id="1373" PostTypeId="2" ParentId="1372" CreationDate="2014-01-27T18:58:57.027" Score="12" Body="&#xA;&#xA;&lt;h2&gt;Disasters&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mayday_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Air Crash Investigation&lt;/a&gt; (a.k.a. Mayday): &lt;strong&gt;2002 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircrash_Confidential&quot; rel=&quot;nofollow&quot;&gt;Aircrash Confidential&lt;/a&gt;: &lt;strong&gt;2011 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Seconds_from_disaster&quot; rel=&quot;nofollow&quot;&gt;Seconds From Disaster&lt;/a&gt;: &lt;strong&gt;2004 - now&lt;/strong&gt; - not all aircraft related&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.channel4.com/programmes/terror-in-the-skies&quot; rel=&quot;nofollow&quot;&gt;Terror In The Skies&lt;/a&gt;: &lt;strong&gt;2013 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Documentaries&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airplane_Repo&quot; rel=&quot;nofollow&quot;&gt;Airplane Repo&lt;/a&gt;: &lt;strong&gt;2010 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/AFP%3a_American_Fighter_Pilot&quot; rel=&quot;nofollow&quot;&gt;American Fighter Pilot&lt;/a&gt;: &lt;strong&gt;2002&lt;/strong&gt; -  &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dangerous_Flights&quot; rel=&quot;nofollow&quot;&gt;Dangerous Flights&lt;/a&gt;: &lt;strong&gt;2012 - now&lt;/strong&gt; - follows a team of ferry pilots&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flying_Wild_Alaska&quot; rel=&quot;nofollow&quot;&gt;Flying Wild Alaska&lt;/a&gt;: &lt;strong&gt;2011 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Jetstream_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Jet Stream&lt;/a&gt;: &lt;strong&gt;2008&lt;/strong&gt; -  follows 8 pilots training with the Royal Canadian Air Force to fly one of the most advanced supersonic tactical fighter jets in the world &amp;mdash; the CF-18 Hornet&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ice_Pilots_NWT&quot; rel=&quot;nofollow&quot;&gt;Ice Pilots&lt;/a&gt;:  &lt;strong&gt;2009 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.discovery.ca/showpage.aspx?sid=38987&quot; rel=&quot;nofollow&quot;&gt;Mighty Planes&lt;/a&gt;: &lt;strong&gt;2012 - now&lt;/strong&gt; - series about unique large aircraft&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/The_Aviators_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;The Aviators&lt;/a&gt;: &lt;strong&gt;2010 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Airports&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airport_24/7%3a_Miami&quot; rel=&quot;nofollow&quot;&gt;Airport 24/7: Miami&lt;/a&gt;: &lt;strong&gt;2012 - now&lt;/strong&gt; - follows the daily life at Miami International Airport&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Animal_Airport&quot; rel=&quot;nofollow&quot;&gt;Animal Airport&lt;/a&gt;: &lt;strong&gt;2000 - now&lt;/strong&gt; - &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://natgeotv.com/uk/ultimate-airport-dubai&quot; rel=&quot;nofollow&quot;&gt;Ultimate Airport: Dubai&lt;/a&gt;: &lt;strong&gt;2013 - now&lt;/strong&gt; - follows the daily life and construction at the world's 2nd busiest airport&lt;sup&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/World%27s_busiest_airports_by_international_passenger_traffic&quot; rel=&quot;nofollow&quot;&gt;1&lt;/a&gt;&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Sitcoms&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_America_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Air America&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Come_Fly_with_Me_%282010_TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Come Fly With Me&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wings_%28NBC_TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Wings&lt;/a&gt;: &lt;strong&gt;1990 - 1997&lt;/strong&gt; - drama/comedy&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Dramas&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airwolf&quot; rel=&quot;nofollow&quot;&gt;AirWolf&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Baa_Baa_Black_Sheep_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Black Sheep Squadron&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Blue_Thunder_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Blue Thunder&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/El_Se%C3%B1or_de_los_Cielos&quot; rel=&quot;nofollow&quot;&gt;El Señor de los Cielos&lt;/a&gt;: &lt;strong&gt;2013 - now&lt;/strong&gt; - Spanish language, English subtitles&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/LAX_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;LAX&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pan_Am_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;Pan Am&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pensacola%3a_Wings_of_Gold&quot; rel=&quot;nofollow&quot;&gt;Pensacola: Wings of Gold&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Supercarrier_%28TV_series%29&quot; rel=&quot;nofollow&quot;&gt;SuperCarrier&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-20T22:49:01.680" LastActivityDate="2014-04-20T22:49:01.680" CommentCount="0" CommunityOwnedDate="2014-01-27T18:58:57.027" ContentLicense="CC BY-SA 3.0" />
  <row Id="1375" PostTypeId="1" AcceptedAnswerId="1376" CreationDate="2014-01-27T23:03:09.953" Score="-2" ViewCount="419" Body="&lt;p&gt;This question aims to serve as a &lt;a href=&quot;https://meta.stackexchange.com/questions/11740/what-are-community-wiki-posts&quot;&gt;Community Wiki&lt;/a&gt; resource.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Feel free to edit the list of aviation-related movies below!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/1372/what-aviation-related-tv-shows-are-there/1373&quot;&gt;What aviation-related TV shows are there?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-12T19:48:13.680" Title="What aviation-related movies are there?" Tags="&lt;general-aviation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2014-02-03T00:39:26.597" ContentLicense="CC BY-SA 3.0" />
  <row Id="1376" PostTypeId="2" ParentId="1375" CreationDate="2014-01-27T23:03:49.083" Score="3" Body="&#xA;&#xA;&lt;h2&gt;Action&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0092099/&quot; rel=&quot;nofollow&quot;&gt;Top Gun&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Comedy&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0080339/&quot; rel=&quot;nofollow&quot;&gt;Airplane!&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0120797/&quot; rel=&quot;nofollow&quot;&gt;Pushing Tin&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Drama&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0065377/&quot; rel=&quot;nofollow&quot;&gt;Airport&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0080545/&quot; rel=&quot;nofollow&quot;&gt;Cloud Dancer&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt1907668/&quot; rel=&quot;nofollow&quot;&gt;Flight&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0137799/&quot; rel=&quot;nofollow&quot;&gt;Ground Control&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0338751/&quot; rel=&quot;nofollow&quot;&gt;The Aviator&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0086197/&quot; rel=&quot;nofollow&quot;&gt;The Right Stuff&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Factual&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0475994/&quot; rel=&quot;nofollow&quot;&gt;One Six Right&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt1112756/&quot; rel=&quot;nofollow&quot;&gt;Speed and Angels&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0475276/&quot; rel=&quot;nofollow&quot;&gt;United 93&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;http://www.tcm.com/this-month/article/160793|0/Aviation-In-Film-Tuesdays-in-July.html&quot; rel=&quot;nofollow&quot;&gt;Turner Classic Movies&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;TCM lists 43 aviation movies in it's catalogue&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Miscellaneous&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0346156/?ref_=nv_sr_1&quot; rel=&quot;nofollow&quot;&gt;Sky Captain and the World of Tomorrow&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0065377/?ref_=nv_sr_1&quot; rel=&quot;nofollow&quot;&gt;Airport&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0071110/?ref_=nv_sr_2&quot; rel=&quot;nofollow&quot;&gt;Airport 1975&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0075648/?ref_=nv_sr_3&quot; rel=&quot;nofollow&quot;&gt;Airport '77&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0078740/?ref_=nv_sr_4&quot; rel=&quot;nofollow&quot;&gt;Concorde... Airport '79&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wings_(1927_film)&quot; rel=&quot;nofollow&quot;&gt;Wings&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Best picture, 1st Academy Awards (1927)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0099575/?ref_=nv_sr_3&quot; rel=&quot;nofollow&quot;&gt;Fire Birds&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0118571/?ref_=nv_sr_1&quot; rel=&quot;nofollow&quot;&gt;Air Force One&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0057811/?ref_=fn_al_tt_1&quot; rel=&quot;nofollow&quot;&gt;633 Squadron&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0116629/?ref_=nv_sr_2&quot; rel=&quot;nofollow&quot;&gt;Independence Day&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt1628841/plotsummary?ref_=tt_ov_pl&quot; rel=&quot;nofollow&quot;&gt;Independence Day: Resurgence&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Coming soon to a theatre near you!&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0050204/?ref_=fn_al_tt_5&quot; rel=&quot;nofollow&quot;&gt;Bombers B-52&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0046806/?ref_=fn_al_tt_1&quot; rel=&quot;nofollow&quot;&gt;The Bridges at Toko-Ri&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0057090/?ref_=nm_flmg_act_29&quot; rel=&quot;nofollow&quot;&gt;A Gathering of Eagles&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0043270/?ref_=nm_flmg_act_66&quot; rel=&quot;nofollow&quot;&gt;Air Cadet&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0059797/?ref_=nv_sr_1&quot; rel=&quot;nofollow&quot;&gt;Those Magnificent Men in Their Flying Machines or How I Flew from London to Paris in 25 hours 11 minutes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0094712/?ref_=fn_tt_tt_11&quot; rel=&quot;nofollow&quot;&gt;Bat*21&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0059183/?ref_=nm_flmg_act_20&quot; rel=&quot;nofollow&quot;&gt;The Flight of the Phoenix&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The good one with Jimmy Stewart. Not the remake.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0043859/?ref_=nm_flmg_act_54&quot; rel=&quot;nofollow&quot;&gt;No Highway in the Sky&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0091059/?ref_=nv_sr_5&quot; rel=&quot;nofollow&quot;&gt;Flight of the Navigator&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0408790&quot; rel=&quot;nofollow&quot;&gt;Flightplan&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-12T19:48:13.680" LastActivityDate="2015-10-12T19:48:13.680" CommentCount="0" CommunityOwnedDate="2014-01-27T23:03:49.083" ContentLicense="CC BY-SA 3.0" />
  <row Id="1377" PostTypeId="1" CreationDate="2014-01-27T23:47:49.167" Score="5" ViewCount="258" Body="&lt;p&gt;So every once in awhile I see an article talking about the air traffic control strikes in Europe like this one:  &lt;a href=&quot;http://english.cntv.cn/20140124/102596.shtml&quot; rel=&quot;nofollow&quot;&gt;European air traffic controllers to strike&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does this affect me if I am flying to Europe?  Do they just close the doors and all airspace becomes uncontrolled airspace?  I'm guessing not, but that's what I envision when I hear that!  What happens if they go on strike while I'm over the ocean on my way there?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-28T02:02:30.527" LastActivityDate="2014-01-28T07:33:54.040" Title="How do the European ATC strikes affect us as pilots?" Tags="&lt;air-traffic-control&gt;&lt;eu&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1378" PostTypeId="1" AcceptedAnswerId="1379" CreationDate="2014-01-28T00:05:33.537" Score="15" ViewCount="70251" Body="&lt;p&gt;As I understand it, the FAA certifies certain aircraft types for IFR flight in general. All aircraft of that type are then certified, not something you have to do with each individual aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the minimum requirements for aircraft to be certified for IFR? Is it all location-sensing equipment?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a bonus: can I get a single aircraft that is only VFR certified to be IFR certified if I add more equipment?&lt;/p&gt;&#xA;" OwnerUserId="13" LastEditorUserId="97" LastEditDate="2014-03-21T03:57:22.560" LastActivityDate="2016-02-02T10:45:33.993" Title="What are the FAA requirements for an aircraft to be IFR certified?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;aircraft-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1379" PostTypeId="2" ParentId="1378" CreationDate="2014-01-28T00:24:36.083" Score="10" Body="&lt;p&gt;As you say, the FAA certifies an aircraft for certain &quot;kinds of operation&quot;.  For a normal category airplane certified under 14 CFR 23, it basically says that it must be &quot;established appropriate to the installed equipment&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§23.1525   Kinds of operation.&lt;/strong&gt;&lt;br&gt;&#xA;  The kinds of operation authorized (e.g. VFR, IFR, day or night) and the meteorological conditions (e.g.&#xA;  icing) to which the operation of the airplane is limited or from which&#xA;  it is prohibited, must be established appropriate to the installed&#xA;  equipment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The installed equipment required for IFR flight (beyond that required for VFR flight)  is listed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=ae21a142e1d5d86d12a58b1472c62fa2&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.3.7.3&amp;amp;idno=14&quot;&gt;91.205&lt;/a&gt;(d) and is mostly equipment used to communicate with ATC and to maintain control of the airplane when flying without visual reference to the ground (so no navigation equipment is specified):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.205   Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Instrument flight rules. For IFR flight, the following instruments&#xA;  and equipment are required:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Instruments and equipment specified in paragraph (b) of this&#xA;  section, and, for night flight, instruments and equipment specified in&#xA;  paragraph (c) of this section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Two-way radio communication and navigation equipment suitable for&#xA;  the route to be flown.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Gyroscopic rate-of-turn indicator, except on the following&#xA;  aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Airplanes with a third attitude instrument system usable through&#xA;  flight attitudes of 360 degrees of pitch and roll and installed in&#xA;  accordance with the instrument requirements prescribed in §121.305(j)&#xA;  of this chapter; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Rotorcraft with a third attitude instrument system usable through&#xA;  flight attitudes of ±80 degrees of pitch and ±120 degrees of roll and&#xA;  installed in accordance with §29.1303(g) of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Slip-skid indicator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Sensitive altimeter adjustable for barometric pressure.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) A clock displaying hours, minutes, and seconds with a sweep-second&#xA;  pointer or digital presentation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) Generator or alternator of adequate capacity.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(8) Gyroscopic pitch and bank indicator (artificial horizon).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(9) Gyroscopic direction indicator (directional gyro or equivalent).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as converting an airplane from VFR to IFR, the Type Certificate Data Sheet (TCDS) must specify that the airplane is designed for IFR flight, and then you could add the missing equipment to make it qualify.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-28T00:24:36.083" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1380" PostTypeId="2" ParentId="1199" CreationDate="2014-01-28T03:08:24.517" Score="8" Body="&lt;h1&gt;Private Pilot Airplane Single-Engine Checkride Requirements&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Eligibility Requirements (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c9181abc36bfecf4684a3a110a7f0f6a&amp;amp;node=14:2.0.1.1.2.5.1.2&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.103&lt;/a&gt;)&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Be at least 17 years of age for a rating in other than a glider or balloon&lt;/li&gt;&#xA;&lt;li&gt;Be able to read, speak, write, and understand the English language&lt;/li&gt;&#xA;&lt;li&gt;Instructor logbook endorsement certifying your aeronautical knowledge (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c9181abc36bfecf4684a3a110a7f0f6a&amp;amp;node=14:2.0.1.1.2.5.1.3&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.105&lt;/a&gt;) and that you are prepared for the written test&lt;/li&gt;&#xA;&lt;li&gt;Passed the written test and can present your original embossed Airman Knowledge Test Report &lt;/li&gt;&#xA;&lt;li&gt;Instructor logbook endorsement certifying your flight proficiency (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c9181abc36bfecf4684a3a110a7f0f6a&amp;amp;node=14:2.0.1.1.2.5.1.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.107&lt;/a&gt;)and that you are ready for the flight test&lt;/li&gt;&#xA;&lt;li&gt;Log all required aeronautical experience (below)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Aeronautical Experience (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c9181abc36bfecf4684a3a110a7f0f6a&amp;amp;node=14:2.0.1.1.2.5.1.5&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.109&lt;/a&gt;):&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;40 hours of flight time (35 for 141 schools) that includes:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;20 hours of dual instruction&lt;/li&gt;&#xA;&lt;li&gt;10 hours of solo flight training &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;3 hours of cross-country dual&lt;/li&gt;&#xA;&lt;li&gt;3 hours of night dual (to get an unrestricted license) that includes:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1 cross-country flight of over 100 nautical miles total distance&lt;/li&gt;&#xA;&lt;li&gt;10 takeoffs and 10 landings to a full stop (with each landing involving a flight in the traffic pattern) at an airport&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;3 hours of instrument dual&lt;/li&gt;&#xA;&lt;li&gt;3 hours of dual in preparation for the practical test within 2 calendar months &lt;/li&gt;&#xA;&lt;li&gt;10 hours of solo including&#xA;&lt;ul&gt;&#xA;&lt;li&gt;5 hours of cross-country time&lt;/li&gt;&#xA;&lt;li&gt;1 150 NM solo cross country flight, with full-stop landings at three points and one segment of the flight consisting of a straight-line distance of more than 50 NM between the takeoff and landing locations&lt;/li&gt;&#xA;&lt;li&gt;3 takeoffs and 3 landings to a full stop (with each landing involving a flight in the traffic pattern) at an airport with an operating control tower&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="2143" LastEditDate="2015-02-25T15:30:59.620" LastActivityDate="2015-02-25T15:30:59.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1381" PostTypeId="1" AcceptedAnswerId="1384" CreationDate="2014-01-28T05:04:57.410" Score="31" ViewCount="18831" Body="&lt;p&gt;My explanation of how a constant speed propeller works has always been a little shaky. I know about the &quot;speeder spring,&quot; &quot;counter-weights,&quot; and how it utilizes the engine oil pressure, but I'd love to know of a simple and easy-to-understand diagram and explanation that I can use to really understand it, and then teach it to others?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="22726" LastEditDate="2019-09-18T21:10:47.400" LastActivityDate="2019-09-18T21:55:40.820" Title="How does a constant-speed propeller work?" Tags="&lt;general-aviation&gt;&lt;constant-speed-propeller&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="1382" PostTypeId="1" AcceptedAnswerId="1395" CreationDate="2014-01-28T06:40:14.747" Score="13" ViewCount="1040" Body="&lt;p&gt;A popular airport near me (&lt;a href=&quot;http://airnav.com/airport/KMYF&quot; rel=&quot;noreferrer&quot;&gt;KMYF&lt;/a&gt;) has two parallel runways, 28/10 R/L and a crosswind runway, 5/23. Almost always, 28R/L is in use. I'm sure they knew that there was generally a sea breeze in the area, and the wind typically will be right down the runway or within 10-20 degrees of centerline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure they do prevailing wind study for the area, and my questions are about the study: What are the specifications for the study? Does the study vary in length depending on location? Is there a standard study battery of tests that they use, and do they test things like average temperature during the study to determine runway length (to maximize utility during high density altitude operations)?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="132" LastEditDate="2014-05-09T23:13:48.137" LastActivityDate="2014-05-09T23:13:48.137" Title="How is a prevailing wind/average temperature study conducted to determine the runway direction and length for an airport?" Tags="&lt;faa&gt;&lt;weather&gt;&lt;runways&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1383" PostTypeId="1" AcceptedAnswerId="1386" CreationDate="2014-01-28T06:42:58.370" Score="39" ViewCount="91937" Body="&lt;p&gt;In the United States, if I own land that has an area suitable for landing a small general aviation airplane, can I just create a private runway, or do I have to officially be registered with the FAA or some government agency?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="97" LastEditDate="2014-01-28T06:46:45.757" LastActivityDate="2018-10-15T18:47:51.327" Title="If I own land, can I create a private runway on my property for my own use?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;&lt;airport&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1384" PostTypeId="2" ParentId="1381" CreationDate="2014-01-28T07:11:26.723" Score="37" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/24hoB.jpg&quot; alt=&quot;The pilot valve is resting directly on the flyweights.&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/U5ARz.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Before we get started, I should mention that the most basic constant-speed propellers were driven by balancing air pressure and centrifugal force. The blades were shaped in such a way, or equipped with a counterweight that would cause the blade to intrinsically move to a shallow pitch. However, when air was moved over the blade, it would begin to overpower the counterweight and push the blade to a higher pitch. It's a pretty ingenious design that meant that the prop would automatically be at a high RPM when the plane was moving slowly (takeoff, landing, climbs),  and would automatically move to a higher pitch when the plane sped up for cruise. There is even a single-bladed propeller that utilized this design very efficiently for light aircraft. The problem is that this type of propeller is not pilot-adjustable, and I am assuming you are wondering about adjustable props, so that's what we'll talk about from here on.&lt;/p&gt;&#xA;&lt;p&gt;In the first picture, observe that the pilot valve is resting directly on the flyweights (separated by a bearing). The second picture better depicts the valve system. So we see that the speeder spring is pushing down on the top of the pilot valve's shaft, which is in turn resting on the flyweights.&lt;/p&gt;&#xA;&lt;p&gt;First off, the flyweights are turned by the crankshaft, so any change in engine RPM is immediately reacted to.&lt;/p&gt;&#xA;&lt;p&gt;There are a few ways that the propeller is attached to the piston, and a rack and pinon type gear system is common and easy to imagine. The rack is fixed to the piston so that when it moves, the prop blade's pinion gear is rotated and thus the blade is rotated. Another common type uses a peg that is offset from the center of the blade's circular base. When the piston moves, it pushes or pulls on the peg and because the peg is offset it causes the blade to twist.&lt;/p&gt;&#xA;&lt;h2&gt;Overspeed: When your airspeed increases.&lt;/h2&gt;&#xA;&lt;p&gt;When the RPMs increase, the centrifugal force causes the flyweights to want to spread apart in order to conserve momentum. Because they're in an L shape and have a hinge in the corner, this causes the lower part to rise up, pulling the pilot valve up and compressing the speeder spring. When the pilot valve is raised, pressurized oil from the pump is allowed to flow into the prop hub through a tube that passes through the center of the hub piston. The oil fills a cavity in front of the piston, pushing it backwards. The prop blade is rotated to a higher pitch (closer to feather) which slows the engine RPM. When the RPM is reduced, the flyweights will be under less centrifugal force, and the speeder spring will push them back to equilibrium (on-speed), pushing the pilot valve back down to block the hub oil tube from gaining or losing oil.&lt;/p&gt;&#xA;&lt;h2&gt;Underspeed: When your airspeed decreases.&lt;/h2&gt;&#xA;&lt;p&gt;When the RPMs decrease, there is less centrifugal force acting on the flyweights. Due to their shape as described earlier, they are no longer able to push up on the speeder spring with the same force as before, so the compressed spring will begin to expand. This brings the top of the flyweights in, and their bottoms down. When their bottoms move down, the pilot valve moves down as well and unblocks the hub oil tube. Positive oil pressure in the hub and the blades' built-in tendency to want to move to a low pitch pushes the oil out of the hub and back into the oil system. The piston moves forward and the blades rotate to a low-pitch condition. The flyweights do not necessarily return to equilibrium, especially if you manually set the spring to maximum compression with the prop lever: you want the prop to stay at minimum pitch no matter what.&lt;/p&gt;&#xA;&lt;h2&gt;Loss of oil pressure:&lt;/h2&gt;&#xA;&lt;p&gt;Oil pressure is constantly pushing against the bottom of the pilot valve, trying to force it upwards. The speeder spring is resisting, and while the flyweights are on-speed, the whole system is in equilibrium with the valve blocking the hub tube. When you lose oil pressure, that pressure is no longer holding the valve up and the speeder spring will win, pushing the valve down and allowing the oil to flow out of the hub. This resets the prop to the low-pitch climb setting, giving us maximum power because that's more useful than maximum speed in the emergency situation that is probably about to occur.&lt;/p&gt;&#xA;&lt;h2&gt;So why do we do this?&lt;/h2&gt;&#xA;&lt;p&gt;All propellers are set at a pitch. Theoretically, a propeller is pitched to move forward a certain distance each revolution, just like a screw moving through wood. But unlike wood, air is fluid and difficult to grip. If you imagine screwing a screw into a board, the only way to make it go in faster is to turn it faster. This is because the screw's pitch is fixed. If you could space out the rungs on the screw (increase the pitch) the screw would move through the wood faster but it would become much harder to turn.&lt;/p&gt;&#xA;&lt;p&gt;An airplane's propeller works much the same way. When we first take off, we need to impart maximum power into the air and it doesn't matter if we don't move forward very far for each revolution, because we're not going very fast anyway. We just want to move as much air as possible. But we will reach a certain point where the only way to speed to is to increase the number of prop revolutions, and that's impractical with our engines. The only alternative is to change the pitch of the blade. We change it to a pitch which allows us to move forward a greater distance with each revolution, in exchange for less power being imparted into the air each revolution. Luckily, we don't need to pump out so much energy, just enough to keep us from slowing down.&lt;/p&gt;&#xA;&lt;p&gt;If you like numbers, imagine we have an engine and propeller that theoretically (at perfect efficiency) moves forward 1 foot for each revolution, and it can make 1 revolution per second, giving a maximum forward speed of 1 foot per second. That's perfectly fine when we're taking off: we might be moving forward at 0.5 fps, and we have some air being blown backwards a 0.5 fps. When when we level off at cruise, we're stuck at 1 fps. But we want to go 3 fps and we know our airframe can handle it. The easiest option is to turn the engine three times as fast, but unfortunately that would send some pistons flying out of the cowling. So we have to change the prop pitch to one that moves forward 3 feet for each revolution, that way it's still turning at the same rate, but it will move us forward three times as far. Or more likely we're still going 1 fps but only 1/3 RPM and burning 1/3 the fuel! It's here that you can see the issue: if we're burning 1/3 the fuel, we're only imparting 1/3 the energy into the air through the prop, and there's no way we could climb or accelerate quickly (if at all) at that setting.&lt;/p&gt;&#xA;&lt;p&gt;A final way to think about it is just like the gears on a car. Your transmission allows you to, at 1500RPM, go 10mph or 60mph or any speed in between. The problem is that if you try to accelerate from 10mph to 60mph while maintaining 1500RPM, it will take a much longer time than if you were to bump it up to 2500RPM. High gears are great for cruising and &lt;em&gt;maintaining&lt;/em&gt; speed, but are not great for accelerating. They allow you to keep your RPMs low, your torque low, and your fuel burn low, because you don't need that extra energy. A high prop pitch is exactly the same.&lt;/p&gt;&#xA;&lt;h2&gt;A note about multi-engine aircraft:&lt;/h2&gt;&#xA;&lt;p&gt;They are just the opposite of singles. Where singles require positive oil pressure to increase blade pitch, multis require positive pressure to decrease it. This is because in a multi, you want the propeller to feather automatically if you lose oil pressure (because of an engine failure). This removes a significant amount of drag from that side of the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;They are equipped with either a spring or a nitrogen charge in the hub that is pressurized, pushing the hub piston back to the feathered position. The prop governor works the same way but the pilot valve directs oil to push against the back of the piston, moving it forward and compressing the spring/nitrogen, moving the prop to a lower pitch.&lt;/p&gt;&#xA;&lt;p&gt;Some are also equipped with an unfeathering accumulator. This is a bottle with a piton in the top (also charged with nitrogen) that fills up with oil when the engine is running. When you bring the prop out of high RPM, the bottle is sealed off from the rest of the system. If you lose oil pressure, the prop will feather like it's supposed to, but there will still be pressurized oil in the accumulator. That way if you manage to get your engine issues taken care of, you can push the prop lever full forward, open the valve to the accumulator, and the pressurized nitrogen will force the oil out of the bottle to put the whole system under positive pressure for a few seconds. This positive pressure moves the hub piston forward and unfeathers the prop.&lt;/p&gt;&#xA;&lt;p&gt;Now you might think &amp;quot;If multis feather when they lose oil pressure, why are all those twins out on the ramp sitting there with low-pitched props?&amp;quot; Well, they have centrifugal locking pins that disappear when the engine RPM is high enough. If it gets low, they will fall back down into a groove around the hub piston or its shaft and lock it into a low-pitch state. This is not a fool-proof system, however, because the pins have been known to stick, and people have been known to shut the engine off with the prop lever less than full-forward. In that case you either need to get some strong guys out there to manually twist the prop back, or you need to waste a chunk of your starter's precious life turning the engine over to create oil pressure to unfeather the prop. Most engines can not start in a feathered state due to the huge drag from the blades being perpendicular to their direction of rotation.&lt;/p&gt;&#xA;&lt;h2&gt;On turboprops:&lt;/h2&gt;&#xA;&lt;p&gt;Although it can vary engine to engine, turboprops use similar systems to multi-engine aircraft but at much higher pressures and with the ability to enter beta mode (reverse pitch). That introduces problems mainly in that the engine will very quickly overspeed with the blade pitch is 0 and the prop is generating no thrust/load. I'm not going to attempt to explain it because I've never really worked with one. &lt;a href=&quot;http://www.aviationpros.com/article/10388997/propeller-control-for-turbo-prop-engines&quot; rel=&quot;noreferrer&quot;&gt;This guy seems to do a good job, though.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-09-18T21:55:40.820" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="1385" PostTypeId="2" ParentId="1377" CreationDate="2014-01-28T07:33:54.040" Score="1" Body="&lt;p&gt;Since these strikes are announced in advance, you will not be caught by surprise half way accross the ocean. If you try to file a flightplan through the soon to be closed airspace, the &lt;a href=&quot;https://www.public.cfmu.eurocontrol.int/PUBPORTAL/gateway/spec/index.html&quot; rel=&quot;nofollow&quot; title=&quot;CFMU public network operations portal&quot;&gt;CFMU&lt;/a&gt; will not accept your plan. There will be no IFR traffic in the airspace before they close down the service. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know about VFR.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-01-28T07:33:54.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1386" PostTypeId="2" ParentId="1383" CreationDate="2014-01-28T07:37:24.943" Score="30" Body="&lt;p&gt;In short: Yes, you can. The FAA doesn't really care, as long as you're not going to interrupt class B or C operations. And honestly as long as you're not hosting a dozen other aircraft, how are they going to tell the difference between a field and an airstrip? If you want it on a chart or you are near special airspace, you need to contact the FSDO and talk to them about it (it's good to do that anyway). They will send someone out to survey it and talk with you, and hopefully approve it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the local authorities that usually ends up being troublesome. Your state/county/city might have laws that apply, and you'll need to find that out on your own. A friend of mine spent just a few days talking/meeting with the FAA on his strip, but spent weeks dealing with the state transportation department and a local ban on new grass strips which he sat right on the border of (as in it was a ban in a 50 mile radius and his house was on mile 50). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Persistence is key, good luck!&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-28T07:37:24.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1387" PostTypeId="1" AcceptedAnswerId="1388" CreationDate="2014-01-28T10:16:38.613" Score="21" ViewCount="11408" Body="&lt;p&gt;I know that some countries (Russia and China for instance) use meters to measure altitude while the rest of the world uses feet. Why isn't this standardized around the world? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess all modern cockpit instruments nowdays offer both unit system measurements, but this must be creating some confusion for pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who decides which measurement units should be used for aircraft altitude? The airlines? ATC? Each country?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are both units of measure used?  Are there any pros or cons with using meters?&lt;/p&gt;&#xA;" OwnerUserId="70" LastEditorUserId="1696" LastEditDate="2015-02-23T21:44:09.687" LastActivityDate="2019-01-18T15:08:00.700" Title="Who decides what measurement units are used for altitude, and why is there no standard?" Tags="&lt;flight-instruments&gt;&lt;measurement&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1388" PostTypeId="2" ParentId="1387" CreationDate="2014-01-28T10:54:41.663" Score="20" Body="&lt;p&gt;Unfortunately, countries tend to want to decide themselves how stuff is supposed to work once you're within their borders. That's why we have different rules and laws, and when you go somewhere else in the world, you might need to know some of the differences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In England they drive on the wrong side of the road, imagine that! :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to have things run smoothly in something so utterly international as aviation, the organization called &lt;a href=&quot;http://www.icao.int&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO&lt;/a&gt; (International Civil Aviation Organization) where most countries of the world are members, dictates the rules, (I believe they are) called the ICAO drafts recommendations which the member states should incorporate into their respective laws and regulations. If they choose not to, they need to inform the ICAO of such deviation, don't know exactly what happens then, but I believe the idea is to at least let everybody know there's a discrepancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ICAO Annex 5 specifies units to use, including units for altitude and actually specifying &lt;strong&gt;meters&lt;/strong&gt; as the primary unit, with feet being accepted as non-SI alternative. Why on earth you'd want to go against the majority on this I don't know, perhaps due to the fact that it's an SI unit and they want to be as much SI as they can. So it's basically up to each country how they want to play it. Most countries stuck with feet.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="9370" LastEditDate="2019-01-18T15:08:00.700" LastActivityDate="2019-01-18T15:08:00.700" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1389" PostTypeId="1" AcceptedAnswerId="1390" CreationDate="2014-01-28T15:13:09.947" Score="15" ViewCount="28494" Body="&lt;p&gt;Airplanes with propellers were invented a long time ago. After that, jet engines came into existence. My question is: why do we still have propeller engines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons I can think of are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They are cheaper;&lt;/li&gt;&#xA;&lt;li&gt;They cannot achieve very high speed;&lt;/li&gt;&#xA;&lt;li&gt;They are not very noisy (though not always).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Besides these, are there any other reasons general aviation airplanes built nowadays don't have jet engines?&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="69" LastEditDate="2014-01-30T03:49:27.727" LastActivityDate="2017-10-23T04:00:10.483" Title="Why are propeller airplanes still made?" Tags="&lt;aircraft-design&gt;&lt;piston-engine&gt;&lt;propeller&gt;&lt;jet-engine&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1390" PostTypeId="2" ParentId="1389" CreationDate="2014-01-28T16:08:58.493" Score="41" Body="&lt;p&gt;Jet engines are only efficient at high altitudes and high speed (25,000+ feet or so and 300+ knots or so true airspeed).  The cost of making and operating an airplane capable of flying there is very high, and most general aviation flights have no need of such performance (or expense) hence, propeller airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reciprocating engine propeller airplanes are relatively efficient at low altitudes and airspeeds, they are more economical for the average types of general aviation flights.  They are also much cheaper to build and operate than a turbine powered airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turboprops fill the efficiency gap between reciprocating and pure jet engines, being most efficient at mid altitudes and airspeeds.  Still more expense and performance than most general aviation flights need though.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-01-28T16:08:58.493" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1391" PostTypeId="2" ParentId="190" CreationDate="2014-01-28T16:11:50.920" Score="0" Body="&lt;p&gt;I believe that the law applies to the information provided the flight plan. Since this document is often used for lawful evidence in other areas of aviation, it would make sense for this to be what is used for &quot;planned&quot; flight.&lt;/p&gt;&#xA;" OwnerUserId="369" LastActivityDate="2014-01-28T16:11:50.920" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1392" PostTypeId="2" ParentId="1343" CreationDate="2014-01-28T16:16:25.617" Score="2" Body="&lt;p&gt;You shouldn't over-torque an engine because you can stress parts more than they're intended to be and cause accelerated wear, or possibly damage or failure.  Modern turbines are designed well past their published limits though, so over-torquing does not necessarily mean anything was hurt, it depends on how far over it went, and how long it lasted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do over torque an engine, the first step is to determine (if possible) how much the limit was exceeded.  What happens next is determined by how much the limit was exceeded.  Up to a point, nothing needs to be done.  After that, varying levels of inspection might be required.  Beyond a certain point, part replacement or rebuild/overhaul might be required.  What exactly happens is specific to each engine.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-01-28T16:16:25.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1393" PostTypeId="2" ParentId="1343" CreationDate="2014-01-28T17:03:33.410" Score="5" Body="&lt;p&gt;This short answer is that you could break something if you over torque the engine.  And that's really about all that we can tell you in general terms.  The manufacturer or an engine repair shop could tell you what is most likely to fail for a particular model, but the failure modes won't be consistent from engine to engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as what to do if you were to over torque one, refer the the aircraft flight manual.  They will have a limitations section, and most airplanes will have &quot;transient&quot; limits in addition to the &quot;normal&quot; limits.  For instance, the limitation could be 100%, with a transient limit of 103% for 10 seconds and 105% for 5 seconds.  If the transient limits are exceeded, then you (or more likely a mechanic on your behalf) would need to refer to the maintenance manual for instructions.  Depending on the severity of the exceedance, it can be anything from simply logging it in the engine logbooks to a complete tear down and overhaul of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll also add that some pilots lean towards pretending that the exceedance never happened, and hope that nobody noticed.  This is not a good idea for several reason, the main one being that something could have been damaged that is not immediately obvious.  Even though things are running correctly now doesn't mean that all is well, and if an inspection is required, it's for a reason.  Another issue is that a lot of modern engines are computer controlled and monitored.  The next time that the computer information is downloaded, maintenance will see the exceedance anyway and if you have flown it since then you could be in even more trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In short, follow the AFM procedures for your airplane.  They are there to help keep you safe!&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-28T17:03:33.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1394" PostTypeId="2" ParentId="1389" CreationDate="2014-01-28T17:12:24.167" Score="14" Body="&lt;p&gt;It is all mission related.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller engines - and I am including turboprops - are much more efficient at lower speeds and altitudes.  Example: the C-130 Hercules cargo aircraft.  It can get in and out of fields much shorter than a turbojet or turbofan can, while trucking a large load, because it has those huge propellers clawing at the air.  Jets, as stated before, have the advantage high and fast.  But that is not the mission of the Hercules.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-29T14:31:44.977" LastActivityDate="2014-01-29T14:31:44.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1395" PostTypeId="2" ParentId="1382" CreationDate="2014-01-28T17:26:58.013" Score="6" Body="&lt;p&gt;FAA &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5300-13&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 150/5300-13A (&quot;Airport Design&quot;)&lt;/a&gt; talks a little about this (you want Appendix 2, &quot;Wind Analysis&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically you start by figuring out what kind of aircraft you want to operate at the airport, and establishing some basic wind limits (specifically, the maximum crosswind and tailwind components you want to deal with).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you call up NOAA's &quot;National Climate Data Center&quot;, tell them where you're looking to build your airport, and see if they can have wind data for the location you're looking to build on.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If NOAA doesn't have data you have a couple of other options -- another nearby airport's wind analysis can be used (if the topography doesn't vary that much and the wind analysis is &quot;recent&quot;), or you may have to perform a wind survey which basically means placing a &lt;a href=&quot;http://en.wikipedia.org/wiki/Anemometer&quot; rel=&quot;nofollow noreferrer&quot;&gt;anemometers&lt;/a&gt; on the site to record the wind speed and direction for a year.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Armed with collected wind data you tally up the number of observations in given wind speed ranges and mark them down on a &quot;wind rose&quot;.&lt;br&gt;&#xA;You then place your runway(s) on the wind rose so that they're aligned with the prevailing winds and determine your &quot;wind coverage&quot; - the amount of time the winds at your site are within your crosswind and tailwind limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advisory circular I linked to shows you how to do this by hand, but there's also software to do this which is how most folks do it. &lt;a href=&quot;https://airports-gis.faa.gov/airportsgis/publicToolbox/windroseForm.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;The FAA even has a handy web form&lt;/a&gt; which will generate the wind rose and runway/crosswind limit bars for you.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that this is just the wind part. As you've alluded to there are a number of other considerations, like terrain: If the prevailing winds favor runway 36, but runway 36 points right at a mountain a mile from the field you might have to align the runway 33 or 03 and sacrifice a perfect headwind for not having pilots fly into the mountain.&lt;br&gt;&#xA;Also as ratchet mentioned the airspace around your proposed site may influence your runway layout and types of operations. &lt;a href=&quot;https://oeaaa.faa.gov/oeaaa/external/portal.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;There's a separate FAA office that deals with &quot;Obstruction Evaluation and Airspace analysis&quot;&lt;/a&gt; and a process to go through to ensure that your airport is not deemed &lt;a href=&quot;https://aviation.stackexchange.com/questions/1282/what-does-objectionable-indicate-on-a-vfr-chart&quot;&gt;&quot;Objectionable&quot;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also as you alluded to in your question there are other considerations like density altitude (local temperature and humidity trends) which will influence design factors like runway length - there's another advisory circular (&lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5325-4&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 150/5325-4B&lt;/a&gt;) that talks about runway design criteria, including length considerations.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For even more than you ever wanted to know about airport design you can check out &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the full 150-series of Advisory Circulars&lt;/a&gt;, which all deal with airports in some way (there are ACs on design, construction, markings, lighting, ARFF, and even how to qualify for and obtain federal aid).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-01-28T17:26:58.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1396" PostTypeId="2" ParentId="1361" CreationDate="2014-01-28T18:27:26.470" Score="14" Body="&lt;p&gt;There is an excellent article on AvWeb about &lt;a href=&quot;http://www.avweb.com/news/system/183174-1.html?redirected=1&quot;&gt;Pop-Up IFR&lt;/a&gt; which goes into more about when pilots should ask for a pop-up IFR clearance.  One of the most importatnt aspects is that if you are starting to get uncomfortable with the weather, or are being forced lower and lower, don't hesitate just because you aren't familiar with the proper procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, you need to talk to ATC.  Find a frequency on your charts or from FSS.  If time is of the essence (you are in deteriorating VFR conditions and it's no better behind you) then ask for help on guard (121.5) rather than endangering yourself while looking for a frequency.  If the weather has gotten so bad that you are no longer able to maintain VFR or can no longer maintain safe terrain clearance, then start climbing immediately and contact ATC as soon as possible for help and a clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More than anything else, &lt;strong&gt;&lt;em&gt;be clear&lt;/em&gt;&lt;/strong&gt; when you are in need.  Don't hesitate to declare an emergency if needed.  They really want to help you in this situation!  All of this applies, even if you aren't 100% legal for IFR flight if it can be done safely (i.e. just because your transponder hasn't received a 24 month inspection in time doesn't mean that you should just keep going lower until you end up clipping a tower).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of that being said, asking for the clearance is done in pretty much the same way as asking for VFR flight following.  Tell them &lt;em&gt;who&lt;/em&gt; you are, &lt;em&gt;where&lt;/em&gt; you are, and &lt;em&gt;what&lt;/em&gt; you need.  Their first priority when they get a request like this is to get you somewhere safe, and then they will ask you for additional information if they need it.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-28T18:27:26.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1397" PostTypeId="1" AcceptedAnswerId="1470" CreationDate="2014-01-28T18:54:42.760" Score="34" ViewCount="29540" Body="&lt;p&gt;Different jet airplanes mount the engines in different ways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flyawaysimulation.com/downloads/files/3435/fsx-virgin-atlantic-airbus-a380/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tLM2Ym.jpg&quot; alt=&quot;A380&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Under the wing&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationexplorer.com/727_facts.htm&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LQBnQm.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;To the fuselage&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the engine location affect aircraft performance?  Is one better than the other?  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2018-05-12T12:04:53.310" LastActivityDate="2018-05-12T12:04:53.310" Title="How does the mounting location of a jet engine affect aircraft performance?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;engine-placement&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1398" PostTypeId="2" ParentId="1397" CreationDate="2014-01-28T19:50:08.973" Score="11" Body="&lt;p&gt;Generally there are 3 engine placements:&#xA;In the tail, on the fuselage in the back, or under the wings. I'll go over the pros and cons of each.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;On the tail&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Pros&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Not many pros, except that it lets one turn a four-holer into a three-holer which is usually more efficient. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Cons&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Generally if you lose the engine in the tail, you risk losing rudder control and you also need a thoroughly reinforced tail, plus you have fuel lines running near the cabin, and you have a significant amount of weight not near the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;On the fuselage in the back&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Pros&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Helps to prevent debris from entering the engine, allows for more room for flaps on the wing, and lighter, more aerodynamic wings since they are not holding up engines, generally allowing for slower approach speeds, also the thrust is closer to the center of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Cons&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Fuel lines near the back of the aircraft,tail has to be a T-tail, as well as reinforced. and center of gravity issues.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Under the wings&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Pros&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Well centered with the center of gravity, allows for more weight shifting in the cabin, and with the bags. The fuel is also kept away from the cabin, and the noise is better spread out through the cabin. In the event that something goes wrong, debris is also less likely to enter the cabin. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Cons&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Much easier to get debris swept into the engine, wings have to be reinforced, lose some area for flaps and slats, raising approach speed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Some useful links&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://adg.stanford.edu/aa241/propulsion/engineplacement.html&quot;&gt;http://adg.stanford.edu/aa241/propulsion/engineplacement.html&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/750042/&quot;&gt;http://www.airliners.net/aviation-forums/general_aviation/read.main/750042/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Performance Wise&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tail:&lt;/strong&gt; Generally not the best, as it has center of gravity issues and drag problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fuselage:&lt;/strong&gt; Good for poor quality runways or low approach speeds but can add weight in reinforcing the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Under the wing:&lt;/strong&gt; Good for getting more load as less center of gravity issues, but raises approach speeds.&lt;/p&gt;&#xA;" OwnerUserId="311" LastEditorUserId="718" LastEditDate="2014-01-29T23:34:14.630" LastActivityDate="2014-01-29T23:34:14.630" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1399" PostTypeId="2" ParentId="1397" CreationDate="2014-01-28T20:14:19.753" Score="13" Body="&lt;p&gt;Mounting jet engines above the wings (see: &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-72&quot; rel=&quot;noreferrer&quot;&gt;Antonov An 72&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_YC-14&quot; rel=&quot;noreferrer&quot;&gt;Boeing YC-14&lt;/a&gt;) takes advantage of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Coand%C4%83_effect&quot; rel=&quot;noreferrer&quot;&gt;Coandă effect&lt;/a&gt; to increase lift and improve short-field takeoff and landing performance. The high-velocity engine exhaust (I'm hand-waving a bit here) adheres to the surface and allows the wing to produce lift somewhat longer than it could otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This layout also vastly reduces the amount of debris and spray that can reach the intakes and damage the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CKTEum.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-28T20:14:19.753" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1400" PostTypeId="1" AcceptedAnswerId="2947" CreationDate="2014-01-28T21:18:31.130" Score="29" ViewCount="31630" Body="&lt;p&gt;What design considerations go into the decision between conventional tails and T-tails?  Functionally the horizontal stabilizer/stabilator are the same in both cases, providing negative lift, the elevator control and a method for pitch trim.  What are the differences though?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I am aware the T-tails I have flown have T-tails for avoiding propwash (PA-44) or aft engine placement (EMB-145).  Are there other reasons for having a T-tail?  What are the aerodynamic consequences a pilot needs to be aware of with a T-tail (e.g. avoiding hard de-rotation on touchdown, issues at high AOA, etc)?&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="22726" LastEditDate="2019-09-06T21:17:06.410" LastActivityDate="2019-09-06T21:17:06.410" Title="How do conventional and T-tails differ?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;t-tail&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1401" PostTypeId="2" ParentId="241" CreationDate="2014-01-28T21:35:18.277" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1381/how-does-a-constant-speed-propeller-work/1384?noredirect=1#comment2221_1384&quot;&gt;See here for my own explanation of the workings of various constant-speed propeller systems.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main operational difference is in power management. With a fixed pitch propeller, if you want more power for climb or speed, you add throttle. When you pitch up, the the RPM will slow due to less air moving through the propeller: suddenly instead of inertia helping you along, your engine is having to work to keep you going. When you pitch down, the RPM will increase due to more air moving through the prop. In this case you have to reduce throttle or you will overspeed the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a constant speed propeller, engine RPM is largely unaffected by the attitude and airspeed of the aircraft. The problem is that if you're flying along at cruise speed with your propeller in cruise configuration and decide to pitch up to climb, your propeller is not able to impart the full energy of the engine into the air. Your climb performance will be diminished or non-existant until you reset the prop to a low pitch. So the main thing to consider is that with a CS prop, maximum power is not always instantly available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also damage the engine easier with a CS prop, in my opinion. With a fixed pitch prop if you go into a dive, your RPM will increase giving you visual and auditory clues that it's happening. With a CS prop, you can enter into a dive and possibly go all the way to Vne without the engine noticing a thing. The problem arises when you're going fast and decide you want to push the prop lever forward: your engine suddenly jumps hundreds or thousands of RPMs in an instant. This is extremely bad for it and that's why many aircraft manuals say not to increase to max RPM above a certain airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, although it is more than made up for in efficiency, engine management is just more complicated with a CS prop. Say you're wanting to maintain a stabilized approach at 100kts. You need to find some combination of throttle and prop settings that gives you enough power to maintain a stable sinkrate, and either has enough drag to slow you down to 100kts, or has minimal drag, allowing you to keep your speed up.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-01-28T21:35:18.277" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1402" PostTypeId="1" AcceptedAnswerId="1404" CreationDate="2014-01-28T21:37:02.663" Score="19" ViewCount="52671" Body="&lt;p&gt;A pilot with a new commercial certificate is excited at the new world of getting-paid-to-fly they have opened up.  That is, until their instructor or good friend reminds them of 14 CFR 119 and the grey line that separates operations that do or do not require an operating certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is cut and dry that a commercial pilot can be paid to do certain things, but when you decide you are going to start doing things for a friend (&quot;yea, I can transport XYZ for you on my next trip to Kalamazoo&quot;) things start to get murky. Especially once your friend starts paying you, you make a habit of transporting things and he tells his friends about your service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what point are you holding out your services to the public and when do you cross the line from private carriage into common carriage?  How far can you go without an operating certificate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for regulatory answers or anything written from a FSDO, basically anything not anecdotal.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-01-31T19:20:33.550" Title="What do the terms 'holding out' and 'common carriage' mean?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;commercial-operations&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1403" PostTypeId="2" ParentId="1402" CreationDate="2014-01-28T21:59:17.280" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%20120-12A.pdf&quot; rel=&quot;nofollow&quot;&gt;Advisory Circular 120-12A&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to part D, it would seem that when you have long-term contracts to serve somewhere between 3 and 18 customers are you likely to be considered a common carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what they're getting at is that those guys who had 18-24 had the ability to serve 18-24 clients at max. So while they were still working private contracts and not open to the general public, they were accepting as many contracts as they were able, which is really no different than holding out to the public. But if you have three full-time aircraft and are flying contracts for two clients on a semi-regular basis, you are not likely to be seen as holding out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a very hard thing to define because there is no right answer. The definition varies between FSDOs and even between operations in question. If you do a lot of research you'll find that the FAA tends to be conservative and will say that operations that may &lt;em&gt;blatantly&lt;/em&gt; fall under private carriage via 120-12A's guidelines must still be a 135 operation or worse. Then another case that strikingly similar might come up and the ruling is that it's okay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only real way to know where that line turns from light gray to dark gray is to call the FSDO and ask.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-28T21:59:17.280" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1404" PostTypeId="2" ParentId="1402" CreationDate="2014-01-28T22:01:27.977" Score="14" Body="&lt;p&gt;Oddly enough, &quot;common carriage&quot; is not defined in the FAR's, but that is because it is a &quot;common law term&quot; and not specific to aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22647&quot;&gt;AC120-12A - Private Carriage Versus Common Carriage of Persons or Property&lt;/a&gt; contains guidance that can be used to help determine whether or not an operation falls under common carriage.  Take a look at it for specific examples, but the &quot;plain language&quot; version is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Common Carriage:&lt;/strong&gt; A carrier becomes a common carrier when it &quot;holds itself out&quot; to the public, or to a segment of the public.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Holding Out:&lt;/strong&gt;  A carrier is holding out when they represent themselves as willing to furnish transportation within the limits of its facilities to any person who wants it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lots of ways to &quot;hold out&quot;, but the basic idea is if &lt;em&gt;someone in the general public comes to you&lt;/em&gt; and asks you to fly them and you agree, you are probably holding out.  Any form of advertising demonstrates a clear sign that you are holding out.  There are also other activities that qualify, so look over the AC if you have further questions, and if that doesn't answer it your best bet is to contact an aviation lawyer.  You could also contact your local FSDO with questions.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as transporting a third part for hire, both common and private carriage require an air carrier certificate issued under 125 or 135 depending on the size of the airplane&lt;sup&gt;1&lt;/sup&gt;. This means that your trip for a friend would be in violation because you don't have the required air carrier operating certificate.  (Thank you @p1l0t for clarifying this for me!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/DA32720D0EB3829386256959004CBCFA?OpenDocument&quot;&gt;119.23&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Operators engaged in passenger-carrying operations, cargo operations,&#xA;  or both with airplanes &lt;strong&gt;when common carriage is not involved&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Each person who conducts operations when common carriage is not&#xA;  involved with airplanes having a passenger-seat configuration of 20&#xA;  seats or more, excluding each crewmember seat, or a payload capacity&#xA;  of 6,000 pounds or more, shall, unless deviation authority is issued--&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Comply with the certification and operations specifications&#xA;  requirements of part 125 of this chapter;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Conduct its operations with those airplanes in accordance with the&#xA;  requirements of part 125 of this chapter; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Be issued operations specifications in accordance with those&#xA;  requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) &lt;strong&gt;Each person who conducts noncommon carriage&lt;/strong&gt; (except as provided in&#xA;  Sec. 91.501 (b) of this chapter) &lt;strong&gt;or private carriage operations for&#xA;  compensation or hire&lt;/strong&gt; with airplanes having a passenger-seat&#xA;  configuration of &lt;strong&gt;less than 20 seats&lt;/strong&gt;, excluding each crewmember seat,&#xA;  and a payload capacity of less than 6,000 pounds shall--&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Comply with the certification and operations specifications&#xA;  requirements in subpart C of this part;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) &lt;strong&gt;Conduct those operations in accordance with the requirements of&#xA;  part 135 of this chapter&lt;/strong&gt;, except for those requirements applicable&#xA;  only to commuter operations; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Be issued operations specifications in accordance with those&#xA;  requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA takes a very dim view of people who start competing with actual air carriers and are unlicensed to do so.  It's a quick way to have your license suspended and end up with some hefty fines and other legal troubles.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; There are of course the regulations that allow operations &quot;in furtherance of a business&quot; which is why I specified a third party.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-31T19:20:33.550" LastActivityDate="2014-01-31T19:20:33.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1405" PostTypeId="1" AcceptedAnswerId="1407" CreationDate="2014-01-28T22:06:03.047" Score="13" ViewCount="7332" Body="&lt;p&gt;When I take commercial flights, or you see turns in the vapour trails, they turn very sharply. What's the reason for this - wouldn't it be more efficient to turn gradually?&lt;/p&gt;&#xA;" OwnerUserId="716" LastEditorUserId="69" LastEditDate="2014-01-29T04:25:19.417" LastActivityDate="2014-03-31T01:31:34.393" Title="Why do commercial flights turn / bank so sharply?" Tags="&lt;air-traffic-control&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1406" PostTypeId="2" ParentId="1405" CreationDate="2014-01-28T22:12:18.023" Score="9" Body="&lt;p&gt;Airliners actually turn relatively slowly, but are often so far away (when viewed from the ground) that they &lt;em&gt;appear&lt;/em&gt; to be turning sharply. An airliner cruising at 35,000 feet is actually over 7 miles away, which makes scale hard to comprehend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the air, riding in an airliner, you may be confusing &lt;em&gt;rate of turn&lt;/em&gt; with &lt;em&gt;roll rate&lt;/em&gt; or &lt;em&gt;angle of bank&lt;/em&gt;. An airliner will roll relatively smoothly into a bank angle of up to 30° (which can seem steep), and a rate of turn (change in compass heading) of between 3° and 1.5° per second. You often don't feel the roll, but will observe the bank by looking out the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for the 1.5-3° turn rate is so that Air Traffic Control can have some way to predict where an aircraft will be in x seconds. &lt;a href=&quot;https://en.wikipedia.org/wiki/ROT_%28aviation%29&quot;&gt;Rate of turn is standardized&lt;/a&gt;, making that possible.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-01-28T22:12:18.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1407" PostTypeId="2" ParentId="1405" CreationDate="2014-01-28T22:15:22.473" Score="22" Body="&lt;p&gt;Airplanes are expected by air traffic control to turn at a &quot;standard rate of turn&quot; which is 3 degrees per second.  This will provide a 90 degree turn in 30 seconds.  A standard rate is used so that controllers can anticipate how long it takes for an airplane to turn to a heading and they can line them up easier.  It also makes the turn happen in a smaller amount of airspace so that two airplanes can be flying in the same general vicinity without getting too close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, at the speeds that jet airplanes travel this would mean a very high angle of bank.  A standard rate turn at 200 KT TAS is about 30 degrees of bank and jets can go much faster than this, which would require even higher bank angles.  They actually limit it to 25 degrees of bank when using a flight director, mainly for passenger comfort.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be impressive when looking out the window and seeing the ground, but don't worry, the airplane is more than designed for it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is used mainly at lower altitudes where there are lots of airplanes.  Once they are up high and airplanes are further apart (and the turns are also usually smaller) they  can bank even less (by using a &quot;half-bank&quot; mode) which adds to passenger comfort.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-31T01:31:34.393" LastActivityDate="2014-03-31T01:31:34.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1408" PostTypeId="2" ParentId="1405" CreationDate="2014-01-28T22:15:31.177" Score="1" Body="&lt;p&gt;Most aircraft tend to make standard rate two-minute turns, as in it would take them two minutes to turn 360 degrees (3 degrees per second). At higher altitudes and higher speeds (or heavier aircraft) they might do half-rate (four minute) turns, which are 1.5 degrees per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So at a higher speed (which high-flying planes are likely to be at), to turn a the same &lt;em&gt;rate,&lt;/em&gt; they must bank more sharply. That's why at higher speeds the halve the rate, so they can reduce the required bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More likely though, it's just your perspective. From your position on the ground it looks like they're turning sharply but in reality it took them several miles to make the turn. From your position in the plane, it's difficult to comprehend how fast you're going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, at higher airspeed speed sharper bank angles are required to keep the plane coordinated during a standard rate turn. This means that when you turn, you feel like you're being pressed down into your seat instead of sideways out of it (like when you take a turn fast in a car). &lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-01-29T03:44:11.633" LastActivityDate="2014-01-29T03:44:11.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1409" PostTypeId="2" ParentId="1387" CreationDate="2014-01-28T22:18:01.897" Score="18" Body="&lt;p&gt;In response to the pros/cons of feet vs. meters, the big advantage that feet have over meters, is that it allows you to use nice human-memorable numbers for cruising altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, we generally use 500ft for visual separation, and 1000ft for separating IFR traffic from other IFR. This translates to roughly 150m and 300m respectively. This means, we can explain IFR cruising altitudes as odd-thousands going east, and even thousands going west (up to FL410).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this were in meters, you'd have to try to explain that going east it's 300m multiplied by odd numbers, and west it's 300m multiplied by even numbers. It's certainly not impossible to figure out in your head, it just isn't as quick and easy. Unfortunately 100m is considered too little separation, and 500m would be an inefficient use of airspace (over-separation), otherwise there might be more of a global push to use meters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, although Russia does use meters, they have actually adopted the international &quot;Flight Levels&quot; (i.e. &quot;climb and maintain FL350&quot; which would be equal to 10650m), so now international flights do not have to change altitude when crossing the border into Russian airspace. However, I believe this is not true for other countries which use meters, such as China, where the separation is typically 300m.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2014-01-28T22:18:01.897" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1410" PostTypeId="1" AcceptedAnswerId="1411" CreationDate="2014-01-28T22:23:25.870" Score="27" ViewCount="2893" Body="&lt;p&gt;Many larger airports (class Bravos) have a landing fee. What's the process for assessing and collecting the fees?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How do these landing fees work with general aviation aircraft?&lt;/li&gt;&#xA;&lt;li&gt;Where can I find out what the fee will be? Is it published?&lt;/li&gt;&#xA;&lt;li&gt;How will I be charged the fee? (Pay before leaving the airport, bill sent to my home, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Is the landing fee a flat rate or is it calculated based on aircraft weight or some other factor?&lt;/li&gt;&#xA;&lt;li&gt;I've heard that the landing fee is generally waived if you buy a few gallons of (overpriced) gas at an FBO, is that true?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Example scenario: I offer to take a friend up for a scenic flight. He lives very close to a moderately busy class B airport while my home airport and FBO is over an hour away from him. I offer to fly into the class B airport to pick him up and then drop him off at the end of the flight.&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="64" LastEditDate="2015-10-30T02:51:41.367" LastActivityDate="2020-05-18T00:10:00.387" Title="How do landing fees work at larger airports?" Tags="&lt;airport&gt;&lt;usa&gt;&lt;landing-fees&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1411" PostTypeId="2" ParentId="1410" CreationDate="2014-01-28T22:26:39.410" Score="25" Body="&lt;p&gt;Well, the short version is that there really isn't a standard (and this applies to small as well as large airports).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some airport authorities charge fees that are billed through the FBO, some don't.&lt;/li&gt;&#xA;&lt;li&gt;Some airport authorities bill you directly, some don't.&lt;/li&gt;&#xA;&lt;li&gt;Normally you pay at the FBO before you leave.  &lt;/li&gt;&#xA;&lt;li&gt;Most of the FBO's set their own fees (although they may come from corporate).&lt;/li&gt;&#xA;&lt;li&gt;Some FBO's don't charge any fees (although not very many these days).&lt;/li&gt;&#xA;&lt;li&gt;Some FBO's waive some (or all) of their fees if you buy fuel, some don't.&lt;/li&gt;&#xA;&lt;li&gt;Most FBO's charge a fee based on the size/class/weight of aircraft, some don't.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;In short, call ahead to the FBO that you will be using and ask them what the fees are and whether or not any of them can be waived.  They are used to this question and will have the information handy for you.&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-28T22:26:39.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1412" PostTypeId="2" ParentId="1400" CreationDate="2014-01-29T08:20:43.977" Score="17" Body="&lt;p&gt;There's a lot to this, and I'm no aircraft engineer, so if there are any other answers, I'll happily delete this. Anyway, from what I've been told:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The T-tail sticks the elevators out of the disturbed air of the wings, prop, and (usually most of) the fuselage which gives you better elevator authority, and makes a tail stall less likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has some drawbacks though, by putting the elevators directly in the (turbulent) separated flow from the wings during a stall can put you in a (more or less) unrecoverable &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_%28flight%29#Deep_stall&quot; rel=&quot;noreferrer&quot;&gt;deep stall&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Deep_stall.svg/200px-Deep_stall.svg.png&quot; alt=&quot;Deep stall&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Picture from the linked Wikipedia article)&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.570" LastActivityDate="2014-01-29T08:20:43.977" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1413" PostTypeId="1" AcceptedAnswerId="1414" CreationDate="2014-01-29T14:08:17.777" Score="22" ViewCount="5318" Body="&lt;p&gt;If an aircraft exceeds its critical Mach number, does it affect the way the aircraft is handled? Are there any significant changes to performance or the safety of the aircraft when above this speed? What actually happens to the aircraft in the first place?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-01-29T22:14:59.457" Title="How does exceeding the critical Mach number of an aircraft affect its operation?" Tags="&lt;safety&gt;&lt;airspeed&gt;&lt;fixed-wing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1414" PostTypeId="2" ParentId="1413" CreationDate="2014-01-29T14:40:14.563" Score="31" Body="&lt;p&gt;At the critical mach number, some part of the aircraft (usually the wing) will have air flowing over it at a speed in excess of mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is not meant to fly at transonic or supersonic speeds, shock waves will flow over the wing. This can either cause the wing to stall, the control surfaces to become unresponsive, or the plane to go into the mach tuck, which is very dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mach tuck is a phenomenon first observed with the P-38 Lightnings and Spitfires in World War II. These planes were so clean that when dive bombing it was possible to exceed their critical mach number. When this happened the center of lift would move back on the wing. This would cause the plane to 'tuck'; the elevators stop functioning, and the plane's dive becomes steeper and steeper until the aircraft is actually partially inverted. Recovery can be attempted by lowering the gear, extending the dive brakes, and lowering the flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In later versions of the P-38 a small 'speed bump' flap was added for diving which caused a more even pressure distribution on the wing, and decreased the chance of entering a mach tuck.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-01-29T22:14:59.457" LastActivityDate="2014-01-29T22:14:59.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1416" PostTypeId="2" ParentId="198" CreationDate="2014-01-29T19:44:24.933" Score="21" Body="&lt;p&gt;Because I'm both a single engine pilot and motorcycle rider, the way I explain risk to new passengers is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Daytime flight over non-mountainous terrain:  Like riding a motorcycle with full gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Daytime flight in instrument conditions or over mountainous terrain in clear air:  Like riding a motorcycle with only a helmet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Night flight over non-mountainous terrain:  Like riding a motorcycle with a helmet but no headlight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Night flight in instrument conditions over non-mountainous terrain:  Like riding a motorcycle at night with a headlight but no helmet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Night flight in instrument conditions over mountainous terrain:  Like riding a motorcycle at night with no helmet, in the rain, over the speed limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any flight in which the pilot says 'watch this sh*t' - Like riding a motorcycle at night with no helmet, over the speed limit, while drunk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a single engine airplane is more dangerous than 'driving to the airport'.&lt;/p&gt;&#xA;" OwnerUserId="534" LastActivityDate="2014-01-29T19:44:24.933" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1417" PostTypeId="1" AcceptedAnswerId="1421" CreationDate="2014-01-29T19:44:29.607" Score="12" ViewCount="472" Body="&lt;p&gt;Are there any considerations to take into account when flying around supersonic aircraft? I know that wake turbulence from large aircraft can pose a threat to smaller planes. Is the same true of the shock waves generated by planes in supersonic flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, do fighter pilots need to be aware of the shock waves caused by other fighter planes in the vicinity?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-01-29T21:45:42.883" Title="Do the shock waves from a supersonic plane affect general aviation planes?" Tags="&lt;jet&gt;&lt;wake-turbulence&gt;&lt;supersonic&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1418" PostTypeId="1" AcceptedAnswerId="1420" CreationDate="2014-01-29T19:52:32.060" Score="73" ViewCount="137780" Body="&lt;p&gt;When a non-pilot hears the word stall, it brings to mind what happens when a car stalls -  the engine quits. It seems like that would be a dangerous scenario in an airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a non-pilot perspective, what happens when an airplane stalls and why is it important for pilots to practice it?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="69" LastEditDate="2014-01-30T04:10:07.613" LastActivityDate="2018-01-06T15:04:53.627" Title="What happens when an airplane stalls and why do pilots practice it?" Tags="&lt;aerodynamics&gt;&lt;aircraft-design&gt;&lt;flight-training&gt;&lt;stall&gt;" AnswerCount="10" CommentCount="0" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="1419" PostTypeId="2" ParentId="1418" CreationDate="2014-01-29T20:08:49.147" Score="17" Body="&lt;p&gt;The stalls that pilots practice are &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_%28flight%29&quot;&gt;aerodynamic stalls&lt;/a&gt; not engine stalls. It happens when the critical angle of attack is exceeded. [Typically the nose is pitched up too much is what it means]. It results in airflow separation that means that the wing no longer is generating any [significant] lift. As soon as the pilot recovers by letting the nose down and regaining some airspeed they are flying again. We practice these for the purpose of being able to recognize the onset of a stall and being able to recover from an inadvertent stall. This is important because while it is actually kind of fun at altitude, near the ground (like while on approach or departure for example) it can be deadly.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="391" LastEditDate="2014-01-30T01:36:24.043" LastActivityDate="2014-01-30T01:36:24.043" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1420" PostTypeId="2" ParentId="1418" CreationDate="2014-01-29T21:13:24.717" Score="71" Body="&lt;p&gt;Stall was an unfortunate choice of words for an engine that suddenly quits since the aerodynamic stall in aviation means something very different and isn't related to the aircraft engine at all&lt;sup&gt;1&lt;/sup&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To a non-pilot, an aerodynamic stall can best be described as the situation where there is not enough air flowing over the wings to create the amount of lift needed to hold up the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason that student pilots practice stalls is to learn the telltale signs that occur just before it happens and to make the recovery procedure automatic.  If pilots can recognize an impending stall, they can take corrective action to either avoid the stall altogether or to recover as quickly as possible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of training, inadvertent stalls typically only occur shortly before landing and after takeoff, when the pilot gets distracted while already at a slow speed.  In both of these situations the airplane is very close to the ground, immediately requiring the correct action from the pilot in order to avoid a crash.  This needs to be instinctive and corrected using &lt;a href=&quot;http://en.wikipedia.org/wiki/Muscle_memory&quot; rel=&quot;noreferrer&quot;&gt;muscle memory&lt;/a&gt; so that it is accomplished as rapidly as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next logical question is usually:  &lt;em&gt;How does a pilot fix an airplane that has stalled?&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fortunately, airplanes are designed so that even during a stall the tail is still effective&lt;sup&gt;2&lt;/sup&gt; and the pilot is able to use it to force the nose down.  This makes the airplane go faster, since it is pointed down towards the ground, and gets more air moving over the wing which allows it to create enough lift for the airplane to start flying again.  During practice it is usually pretty uneventful, but when it happens at a low altitude there may not be enough time to regain flying speed before the airplane crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, AOPA has a great Safety Publication targeting flight instructors called &lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=5318&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Why we teach slow flight and stalls&lt;/em&gt;&lt;/a&gt; which is available on their website.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; However, the sail on a sailboat can also &quot;stall&quot; when there isn't enough wind and since they have been around since 3,000 BC I guess that technically this usage of the word applies to both situations.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; There are some stalls in particular airplane designs known as deep stalls that can be unrecoverable.  I don't think that this is important when describing it to a layperson though.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2018-01-06T15:04:53.627" LastActivityDate="2018-01-06T15:04:53.627" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="1421" PostTypeId="2" ParentId="1417" CreationDate="2014-01-29T21:21:09.750" Score="7" Body="&lt;p&gt;Great question!  I am far from an expert in supersonic flight, but according to this &lt;a href=&quot;http://www.nasa.gov/connect/chat/sonic_boom_chat.html#.Uulv0GRdXw8&quot;&gt;NASA chat transcript&lt;/a&gt;, Ed Haering (an aerospace engineer at NASA's Dryden Flight Research Center in Edwards, Ca. who I would consider to be an expert) answers just this question and says that it isn't a problem for other airplanes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;chetman1020&lt;/strong&gt;: Do sonic booms ever disrupt other things in the air?&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Ed&lt;/strong&gt;: Sonic booms can temporarily dissipate or accentuate a &quot;Sun-Dog,&quot; the small bit of a rainbow off to either side of the Sun&#xA;  caused by high altitude ice crystals. Aircraft are not affected by&#xA;  booms from other aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-01-29T21:45:42.883" LastActivityDate="2014-01-29T21:45:42.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1422" PostTypeId="2" ParentId="1418" CreationDate="2014-01-29T22:07:20.060" Score="34" Body="&lt;p&gt;&lt;strong&gt;An engine stall and an aerodynamic stall are completely different.&lt;/strong&gt; In aviation, an engine stall is referred to as an engine failure, and an aerodynamic stall is simply referred to as a stall.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;For Nerds&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An aerodynamic stall happens when the wing stops producing lift because the &lt;a href=&quot;http://en.wikipedia.org/wiki/Angle_of_attack&quot; rel=&quot;noreferrer&quot;&gt;Angle of Attack&lt;/a&gt; is too high. This is usually, but not always, caused by pulling back on the stick without adjusting power appropriately. Various factors including the weight of the aircraft, flaps, and icing can change the angle of attack the aircraft stalls at.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;For the rest of us&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A stall happens when the wing no longer creates lift. This happens when the speed of the air going over the wing decreases too much. Basically, this is why the advice one mother gave her son during World War I, 'Fly low and slow, I don't want you to get hurt!' makes very little sense aerodynamically speaking.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why pilots practice stalls&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Pilots practice stalls to learn the warning signs that they are entering a stall, and to practice recovering from a stall should they ever end up in one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, as &lt;strong&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/728/brinky&quot;&gt;brinky&lt;/a&gt;&lt;/strong&gt; stated in a comment to this answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While in flight training or when moving to a different airframe,&#xA;  pilots practice putting the aircraft in a stall and then recovering&#xA;  from it to also develop &quot;muscle-type&quot; memory, because stalls are&#xA;  probably the single most unsettling and unpredictable behavior that&#xA;  all aircraft share, and different airframes may react very differently&#xA;  to stalls. Stalls are unforgiving and must be rectified promptly, due&#xA;  to rapid altitude loss.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-01-30T17:26:07.773" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1423" PostTypeId="1" AcceptedAnswerId="15658" CreationDate="2014-01-29T22:32:30.057" Score="10" ViewCount="13634" Body="&lt;p&gt;Is there a general vertical speed that pilots shoot for, or is it entirely by feel/trial-and-error?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2015-06-10T20:41:05.067" Title="What vertical speed at touchdown makes a 'perfect' landing?" Tags="&lt;landing&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1424" PostTypeId="2" ParentId="1423" CreationDate="2014-01-29T23:03:55.737" Score="8" Body="&lt;p&gt;In my experience it's feel/trial-and-error-and-error-and-error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;5 feet off the runway is not a good time to be looking at your VSI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr/&gt;&#xA;Edit&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you're looking at a record of your vertical speed after the fact:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lower numbers are better of course. The goal is to get the rate low enough that the landing gear can absorb the impact without passing on any of the energy. 60 FPM would be 1 foot/second. I'm sure most landing gear would soak that up and earn you praises from your passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've had exactly one &quot;squeeker&quot; - I didn't know I'd touched down until the wheels started moving.  Naturally, I was in a single seat airplane with no witnesses :-(&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="52" LastEditDate="2014-01-30T18:15:20.530" LastActivityDate="2014-01-30T18:15:20.530" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1427" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T00:13:58.780" Score="6" Body="&lt;p&gt;Stall has to do with the attachment of the boundary layer on the upper surface of the wing. When the airflow separates (&lt;a href=&quot;http://www.youtube.com/watch?v=J-xxCkebdZs&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt;) from the surface it stops generating lift and the wing stalls. Lift is the aerodynamic force that keeps the aircraft airborne. It's the reaction of the air to the mass of the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, lightheartedly, to make a &lt;strong&gt;super simple analogy&lt;/strong&gt;, let's say that the equivalent of lift when you walk is the upward reaction of the floor to the mass of your body (&lt;em&gt;which is actually true&lt;/em&gt;); imagine also that you are walking and suddenly a trapdoor opens under your feet (airflow separation). As soon as you feel that you're falling you instinctively open your arms trying to grab something while your eyes are looking around for something to hold on, say a handle or the edges of the trapdoor. This is the situation that one could say that &lt;strong&gt;you have stalled&lt;/strong&gt;. Your normal walking was interrupted and now you're falling. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots train in order to recognize the symptoms and learn where the &lt;em&gt;&quot;handles&quot;&lt;/em&gt; are -i.e. necessary actions to take- when this situation occurs.&lt;/p&gt;&#xA;" OwnerUserId="376" LastActivityDate="2014-01-30T00:13:58.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1428" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T00:26:39.370" Score="1" Body="&lt;p&gt;A stall is when the plane exceeds the linear and predictable. If it hits the air too steep, the flow over the wings collapses into chaos and the behaviour is not always predictable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots practice to develop the skills to recover into the linear range of flight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;/questions/tagged/spins&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spins&amp;#39;&quot; rel=&quot;tag&quot;&gt;spins&lt;/a&gt; and look up the number of people who have died after stalling a &quot;laminar flow&quot; wing (the Gee-Bee racer comes to mind here).&lt;/p&gt;&#xA;" OwnerUserId="729" LastEditorUserId="97" LastEditDate="2014-01-30T00:59:35.907" LastActivityDate="2014-01-30T00:59:35.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1429" PostTypeId="2" ParentId="1423" CreationDate="2014-01-30T00:32:34.973" Score="33" Body="&lt;p&gt;I would argue that the way to think of the perfect landing is not in terms of vertical speed but rather in terms of the G-forces involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thinking in terms of G-force, the perfect force depends on what you're landing on and how long it is. The various conditions I can think of offhand are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;long dry runway, no wind or straight down the runway -- try for a greaser if you want, although arguably a greaser is not the safest landing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;cross wind -- the higher the xwind the more you want a firm touchdown.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;short runway -- firm so you will have effective braking.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;wet runway -- firm, especially if the runway has standing water. The two times that I blew tires on landing was when there was standing water and I didn't plant it firmly enough. In the first case the tires blew before I used the brakes. It was an F27 and one of our pilots was in back at a window seat. He said the two right wheels never rotated at all. I had touched down with a greaser on a puddle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;carrier -- I once checked out a Navy carrier pilot in a 182. It was really hard for him to flare for a landing, since they don't do that. As I remember, he said that they wanted a 4G landing impact.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-01-30T08:11:39.920" LastActivityDate="2014-01-30T08:11:39.920" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1430" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T01:14:04.780" Score="2" Body="&lt;p&gt;A stall can be observed visually on an aircraft with a flexible cloth wing, such as a hang glider or micro-light. To land a hang glider, one deliberately triggers a stall which spreads out across the wing surface, and you can see the fabric going limp.&lt;/p&gt;&#xA;" OwnerUserId="731" LastActivityDate="2014-01-30T01:14:04.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1431" PostTypeId="1" AcceptedAnswerId="1433" CreationDate="2014-01-30T01:49:46.320" Score="29" ViewCount="3199" Body="&lt;p&gt;Since gliders don't have engines, is it possible for them to go around? Are there any extra features on a glider to try to prevent that situation from happening?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="8482" LastEditDate="2015-06-22T06:19:30.873" LastActivityDate="2020-09-11T20:05:08.863" Title="Can a glider make a go-around?" Tags="&lt;glider&gt;&lt;go-around&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1432" PostTypeId="2" ParentId="1431" CreationDate="2014-01-30T02:44:09.570" Score="22" Body="&lt;p&gt;No, a glider can't make a go around, but if they are going fast enough they can make a low pass (which looks like a go around), but that generally means that they won't be in a position to actually land even if they wanted to.  The key to safely managing and landing a glider is energy management.  When coming in to land it can't be too slow and low OR too high and fast (only one factor can be adjusted by trading altitude for airspeed or vice-versa).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most gliders have airbrakes or spoilers which are used to bleed off excess energy.  A typical approach will have them deployed about half way when on final to land so that they can be used like a throttle in an airplane.  If they get low or slow, the airbrakes can be stowed in order to increase the glide ratio (just like adding power in an airplane).  If they get high or fast the airbrakes can be extended further and/or the glider can be slipped in order to decrease the glide ratio (just like reducing power in an airplane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the very high glide ratio and no engine to go around with, they land very similar too an airplane. If you've never flown one, I would highly recommend it.  Not only is it fun, it will make you a better overall pilot! &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-07-14T18:50:13.727" LastActivityDate="2014-07-14T18:50:13.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1433" PostTypeId="2" ParentId="1431" CreationDate="2014-01-30T07:45:22.410" Score="28" Body="&lt;p&gt;No. A (pure) glider cannot make a go-around in the way a powered machine can. The glide path can be influenced by airbrakes, flaps,  chutes or slipping, but mostly those are for reducing your L/D, i.e., steepening the approach (you win again, gravity!).&lt;/p&gt;&#xA;&lt;p&gt;Gaining height without updraft is only possible by converting kinetic energy (speed), and that gain is limited by the stall speed. So while you can rise a few meters when you pull up from landing airspeed, you will find yourself way too high above the runway at minimum speed and hoping for the best.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;https://youtu.be/DxbyDwe1_tk&quot; rel=&quot;nofollow noreferrer&quot;&gt;highly enjoyable* spectacle of a low fly-by of a glider&lt;/a&gt; is achieved by &lt;em&gt;starting&lt;/em&gt; with really high (unlandable) speed which is then converted into height and shortly followed by the inevitable landing**. For some older (mostly wooden) gliders, even this is not a very good idea because they combine a lower V&lt;sub&gt;NE&lt;/sub&gt; with lower L/D ratios,  leaving you low and slow after pulling up from redline speeds.&lt;/p&gt;&#xA;&lt;p&gt;In a glider, you get one chance for a smooth landing (freak thermals excluding). But a properly trained pilot gets used to this very quickly. A proper landing procedure together with brakes, flaps, etc. will bring you down safely.&lt;/p&gt;&#xA;&lt;p&gt;*but not necessarily safe or recommended&lt;/p&gt;&#xA;&lt;p&gt;** unless you catch a proper thermal or dynamic updraft.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="31425" LastEditDate="2020-09-11T20:05:08.863" LastActivityDate="2020-09-11T20:05:08.863" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="1434" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T09:50:29.120" Score="10" Body="&lt;p&gt;When the airplane is at a &quot;regular&quot; angle of attack (angle with the direction of the wind), with the nose more or less forward, the wing works as designed and produces lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airplane turns the nose straight up while continuing to go forward, it's intuitive that the wings stop producing lift, as they are just vertical walls against the wind at this point. (The plane can still fly in this condition if the engines alone can pull all the weight, but that's only common in fighter and acrobat planes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It turns out that the transition between these two is relatively sudden. As the angle of attack increases, wing lift goes up and up and up, then suddenly drops sharply as the smooth air flow detaches from the back of the wing. That's the stall. It can also happen when lowering speed while keeping the angle constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to why pilots practice it, nothing to add to &lt;a href=&quot;https://aviation.stackexchange.com/a/1422/747&quot;&gt;what flyingfisch said&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="747" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-08-22T00:40:10.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1435" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T10:03:12.160" Score="4" Body="&lt;p&gt;&quot;Stall&quot; in aviation generally means an aerodynamic stall. An &quot;engine stall&quot; would be called just that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an excellent understandable writeup of an Airbus crash from a stall, Air France flight 447, on the UK's &lt;a href=&quot;http://www.telegraph.co.uk/technology/9231855/Air-France-Flight-447-Damn-it-were-going-to-crash.html&quot; rel=&quot;noreferrer&quot;&gt;Daily Telegraph&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wing provides lift to a plane as a direct result of the air flowing over the surface. A stationary plane falls - without airspeed, the wings cannot provide lift. A stall occurs when the airspeed falls too low, and the lift provided by the wings cannot maintain flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airspeed can fall too low for several reasons; for AF447 it was the most common case, that the plane's angle of attack was raised too high, and the engines could not provide enough thrust to keep the plane flying above its stall speed. In this scenario, memory of stall practices should kick in and the pilot should point the nose down to regain airspeed, allowing the wings to provide more lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the article suggests that the Airbus controls take commands rather than being a modifiable reflection of the current state of the aircraft, so once the stick was released it wasn't apparent that the plane was trying to climb to the other pilot. Eventually airspeed dropped so low that the airspeed sensors themselves switched off, silencing the stall warning. When the pilots realised the mistake and pointed the nose back down, the increasing airspeed re-enabled the airspeed sensors, which restarted the stall warning, perhaps confusing the crew further. The captain realised just before impact: &quot;10 degrees of pitch...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practising of scenarios is to prepare crew so that in the event of some danger or failure, they do not panic but respond appropriately and correct the problem. &lt;/p&gt;&#xA;" OwnerUserId="748" LastActivityDate="2014-01-30T10:03:12.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1436" PostTypeId="1" CreationDate="2014-01-30T10:42:08.510" Score="49" ViewCount="88259" Body="&lt;p&gt;When looking at an airplane, what are the main external features I should look at if I want to determine if it is an Airbus or a Boeing (shape of the tail, fuselage, winglets, wings, etc.)? Same questions from a passenger point of view, quietly seated inside?&lt;/p&gt;&#xA;" OwnerUserId="113" LastActivityDate="2021-01-27T15:43:34.040" Title="How can I tell apart an Airbus from a Boeing?" Tags="&lt;aircraft-design&gt;&lt;boeing&gt;&lt;airbus&gt;" AnswerCount="13" CommentCount="2" FavoriteCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="1437" PostTypeId="2" ParentId="1400" CreationDate="2014-01-30T11:10:25.457" Score="5" Body="&lt;p&gt;The considerations in the roe's answer are entirely correct but there might be other factors to take into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, it is true that using conventional tail leads to the fact that the airflow over the tail might be disturbed by the main wing and/or the engines and/or the fuselage. However, the downwash induced by the main wing on the flow is taken into account (for the cruise conditions) in the design of the tail in order to reduce some negative aspects of the interaction between the main wing and the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another major difference between these two configurations concerns the stability. As I already explained in this &lt;a href=&quot;https://aviation.stackexchange.com/a/453/113&quot;&gt;answer&lt;/a&gt;, the tail is used to create some lift that is required to fulfil the trim relations. Regarding the &quot;vertical&quot; force equilibrium equation, there is no real difference between the two configurations but there is a big one for the moment equilibrium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that you have the same amount of lift generated by the both configurations (this is relevant due to the &quot;vertical&quot; force equilibrium), a quick sketch will convince you that both the angle and the lever arm are different. The conclusion of this study cannot be drawn without a specific example but I hope it is clear for you that stability is really impacted by the choice of the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a structural point of view, when flying transonic (or even supersonic) it is not good to have a T-tail configuration because it usually induces flutter on the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, at a lower level but still a difference, using a T-tail increases the wake (compared to a conventional configuration, where the tail is almost in the wake of the main wings and the fuselage) behind your aircraft and thus the drag you need to overcome is larger.&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-01-30T11:10:25.457" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1438" PostTypeId="2" ParentId="1436" CreationDate="2014-01-30T13:27:42.273" Score="9" Body="&lt;p&gt;Externally, focus on the fuselage shape.  The top of the fuselage on an airbus runs level until very near the aft end.  A Boeing fuselage is more conical at the rear end, with the top curving down to meet the bottom line curving up.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Internally, look at the safety briefing card.  Remember, the interior fit out of planes is determined by the airline, not the manufacturer.&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-01-30T13:27:42.273" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1439" PostTypeId="1" AcceptedAnswerId="1440" CreationDate="2014-01-30T15:10:47.067" Score="23" ViewCount="10335" Body="&lt;p&gt;Is there generally a minimum altitude for ejecting in order for the sequence to function reliably (all the way to opening the chute, and slowing down to a survivable descent rate)? I've seen ejector seats test being done on the ground, don't know if there were actually test pilots in those seats though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w48hW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w48hWm.jpg&quot; alt=&quot;Low-Leve F-16 Ejection&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume all bets are off if you're not wings level (obviously a low-level inverted ejection has a 0% chance of success).&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="718" LastEditDate="2014-01-31T20:59:21.857" LastActivityDate="2017-02-27T23:09:22.077" Title="Is there a minimum altitude for ejection seats?" Tags="&lt;military&gt;&lt;ejection-seat&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1440" PostTypeId="2" ParentId="1439" CreationDate="2014-01-30T16:02:32.047" Score="23" Body="&lt;p&gt;&lt;strong&gt;It depends on the ejection seat.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern &lt;a href=&quot;https://en.wikipedia.org/wiki/Ejection_seat#Zero-zero_ejection_seat&quot;&gt;zero-zero ejection seats&lt;/a&gt; are designed to be usable at zero speed, zero altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older ejection seats had different minimums which varied from model to model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note, the early F-104 ejection seats required quite a bit of altitude to deploy properly, since the pilot exited through the bottom of the aircraft. This was done because there was some concern that the pilot would hit the F-104's T-tail with a standard ejection seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that it may actually be possible to eject from an inverted aircraft. According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Ejector_seat&quot;&gt;Wikipedia&lt;/a&gt; (bold added for emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The minimal ejection altitude for ACES II seat in inverted flight is&#xA;  about 140 feet (43 m) above ground level at 150 KIAS. While the&#xA;  Russian counterpart - &lt;strong&gt;K-36DM has the minimal ejection altitude from&#xA;  inverted flight of 100 feet (30 m) AGL.&lt;/strong&gt; When an aircraft is equipped&#xA;  with the Zvezda K-36DM ejection seat and the pilot is wearing the&#xA;  КО-15 protective gear, he is able to eject at airspeeds from 0 to&#xA;  1,400 kilometres per hour (870 mph) and altitudes of 0 to 25 km (16 mi&#xA;  or about 82,000 ft). The K-36DM ejection seat features drag chutes and&#xA;  a small shield that rises between the pilot's legs to deflect air&#xA;  around the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-01-30T17:33:44.377" LastActivityDate="2014-01-30T17:33:44.377" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1441" PostTypeId="2" ParentId="1418" CreationDate="2014-01-30T16:22:17.250" Score="2" Body="&lt;p&gt;In paragliding, the pilot stalls the wing on purpose sometimes in order to recover the glider from some situation - when the lines are messed up or there's something else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is similar to rebooting your computer.&lt;/p&gt;&#xA;" OwnerUserId="756" LastActivityDate="2014-01-30T16:22:17.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1442" PostTypeId="2" ParentId="114" CreationDate="2014-01-30T16:44:37.377" Score="3" Body="&lt;p&gt;Regulations regarding UAVs are very restrictive in controlled airspace. Whenever a company wants to test out a UAS, they have to request a block of airspace from the FAA (or local ATC body). This block is restricted to UAS traffic. No manned aircraft are allowed in that area for the duration of the test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently companies are working with the FAA to integrate UAVs into the regular airspace system. Recently, the FAA designated 6 states as test sites for the FAA to test UAVs.&lt;/p&gt;&#xA;" OwnerUserId="757" LastActivityDate="2014-01-30T16:44:37.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1443" PostTypeId="1" AcceptedAnswerId="1445" CreationDate="2014-01-30T17:05:50.543" Score="11" ViewCount="3873" Body="&lt;p&gt;&lt;strong&gt;Primary target&lt;/strong&gt;: An aircraft not reporting mode-C, the only thing the controller has is the return on the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a controller reports a primary target as traffic to other aircraft, the controller does not have the altitude of the target. Given this, I conclude that ATC radar does not have the altitude (angle-up) to the target, and only provides azimuth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So then without the altitude, how does the radar-system know where to put the target laterally on the screen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example, a radar picks up a target that is 10 miles from the station. If the target is 0 AGL, the proper position would be 10 miles out. However, if the target is at 15,000ft, the proper position would be 9.5 miles out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the difference is so small, does the radar just put the target at 10 miles, and the FAA separation guidelines factor in the discrepancy?&lt;/p&gt;&#xA;" OwnerUserId="757" LastActivityDate="2017-04-17T17:26:02.030" Title="How do ATC radars know where to position a primary target?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1444" PostTypeId="2" ParentId="1439" CreationDate="2014-01-30T17:31:06.747" Score="13" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ejection_seat&quot;&gt;Pilots have successfully ejected at negative altitudes&lt;/a&gt; in a handful of instances, after being forced to ditch in water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Documented evidence exists that pilots of the &lt;a href=&quot;http://www.ejectionsite.com/eunderh2o.htm&quot;&gt;US&lt;/a&gt; and &lt;a href=&quot;http://www.bharat-rakshak.com/NAVY/History/1970s/Pasricha.html&quot;&gt;Indian&lt;/a&gt; Navies have performed this feat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also: I once read, but cannot now locate, the citation awarded a pilot of the USAF for the world record lowest altitude successful (i.e. the pilot survived) emergency ejection from a stricken aircraft over land: sixteen feet below ground level.  Apparently the young pilot was practicing with his T-33 single-engine trainer when the engine flamed out and could not be restarted.  The pilot observed the flat desert below, crossed by several paved roads and highways.  One road seemed to be completely clear of traffic, so he opted for a gear-down dead-stick landing on it, hoping to minimize damage to the aircraft.  He discovered only after touchdown that the paved strip was not a road at all but a flash flood drainage ditch, wide enough for the fuselage but not the wings.  The aircraft was seriously damaged and set on fire.  The damage prevented the canopy from opening, so the pilot used the ejection seat to escape burning to death.  He survived with minor burns, some compression damage to his spine, and two broken ankles.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-01-30T17:31:06.747" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1445" PostTypeId="2" ParentId="1443" CreationDate="2014-01-30T17:38:40.630" Score="11" Body="&lt;p&gt;Primary radar, even modern digital systems, do not give any possibility to the controller to determine altitude.  The digital system has that capability, but civil ATC does not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In primary radar displays usually just the azimuth and range are plotted. So an aircraft at 15.000 ft 9.5 NM away will be plotted on 10 NM distance, just like an aircraft at 0 ft 10NM away. Usually the secondary radar is collocated with the primary so secondary targets can be displayed using the same projection (disregarding the altitude). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you now apply horizontal separation based on this projection, you will never bust the separation minima. It is a conservative way of providing separation, but when there is no altitude information it is the best possible way. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that this does not only apply to primary targets, but also to Mode-A only targets&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-09-18T09:23:34.873" LastActivityDate="2014-09-18T09:23:34.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1446" PostTypeId="1" AcceptedAnswerId="1447" CreationDate="2014-01-30T17:58:15.200" Score="18" ViewCount="20238" Body="&lt;p&gt;I imagine that the tires on commercial jets wear out pretty fast with all those squealing landings as the tire suddenly has to spin up from zero to the speed of landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How many landings does any average commercial airliner tire last before it is discarded?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before landing, why not have a small motor assembly on the landing gear to spin up the tires to the correct speed? Surely this would avoid the degrading tire burn. The tire might last a lot longer and might even offset the cost of the motor assembly.&lt;/p&gt;&#xA;" OwnerUserId="759" LastEditorUserId="1696" LastEditDate="2015-02-11T20:22:26.000" LastActivityDate="2018-09-27T09:35:59.280" Title="How long do airliner tires last? Can this be improved?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1447" PostTypeId="2" ParentId="1446" CreationDate="2014-01-30T18:43:03.027" Score="11" Body="&lt;p&gt;I've heard that airliners' tires will last about 200-250 depending on how many hard landings are made. Bizjet tires will last longer, and light aircraft tires will last indefinitely, depending on how gentle you are and what kind of surface you're landing on. I had one start cracking around the wall and just looking unsafe long before the treads ever started to wear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the spin-up idea, it's been proposed many many times, but generally always rejected due to weight and maintenance costs. However, now that fuel is by far the main expense in an airliner's trip, companies are looking for any way to reduce fuel burn. As it turns out, taxiing an airliner burns quite a bit of fuel. They've already started turning one engine off for long taxis, and I think that electric wheel motors will be the next big thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The motors have gotten light enough and strong enough that they are a now a viable option. They can be powered by the APU or by a set of batteries (which are also now becoming light enough, see the 787 when they get the kinks worked out). So when they get around to putting them on aircraft for taxiing purposes, you can bet that they'll be spun-up right before landing.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-30T18:43:03.027" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1448" PostTypeId="2" ParentId="1436" CreationDate="2014-01-30T18:49:19.950" Score="14" Body="&lt;h1&gt;Externally&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The empennage (tail section) is consistent on most Boeings and Airbuses. An Airbus will have a bit of the fuselage sticking out behind the tail planes, whereas most Boeing aircraft have the tail planes right up against the rear of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Internally&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The internal appearance of airliners vary widely since it is up to the airline, not the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Comparison&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Airbus a300&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X6VT1.jpg&quot; alt=&quot;a300&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Boeing 737&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qQlVs.jpg&quot; alt=&quot;737&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2015-03-02T13:52:42.327" LastActivityDate="2015-03-02T13:52:42.327" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1449" PostTypeId="1" AcceptedAnswerId="1455" CreationDate="2014-01-30T19:05:12.123" Score="22" ViewCount="34888" Body="&lt;p&gt;&lt;strong&gt;Are full flaps ever used on takeoff?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One flying book I read strongly discouraged anything more than quarter flaps on most planes due to the amount of drag produced. I was just wondering if there are any scenarios where full flaps might be necessary.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="65" LastEditDate="2015-03-12T19:08:24.540" LastActivityDate="2015-07-26T00:24:41.593" Title="Should full flaps be deployed on takeoff?" Tags="&lt;aerodynamics&gt;&lt;takeoff&gt;&lt;flaps&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1450" PostTypeId="2" ParentId="1449" CreationDate="2014-01-30T20:14:41.097" Score="5" Body="&lt;p&gt;Typically more flaps will get you in the air sooner, but due to the added drag your climb will be shallower. So when the runway is really short and there are no obstacles, full flaps might be the solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are aircraft that are not certified for full flap take-offs and in some cases that additional drag might in fact reduce the performance so badly that the take-off run will be extended. The operating manual will provide guidance. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-04T01:10:25.880" LastActivityDate="2014-02-04T01:10:25.880" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1451" PostTypeId="2" ParentId="1449" CreationDate="2014-01-30T20:27:33.003" Score="0" Body="&lt;p&gt;As a certification requirement, all planes must be able to climb from sea level at max gross weight with full flaps deployed, in standard day conditions.  As has been noted by others, the rate of ciimb will be anemic.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the PA-28 that I fly, the third notch of flaps adds a lot of drag and very little lift.  POH procedure is to use two notches, not three, of flaps for a short field takeoff.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-01-30T22:51:29.623" LastActivityDate="2014-01-30T22:51:29.623" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1452" PostTypeId="1" CreationDate="2014-01-30T21:17:39.730" Score="14" ViewCount="1096" Body="&lt;p&gt;I'm planning on getting my CFI certificate and I would like to purchase a Cessna 172 to rent to students and provide instruction in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the legal requirements for me to do so?  Are there specific things I need to do beyond 100 hour inspections?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best way to set something like that up to provide personal liability protection?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="69" LastEditDate="2014-02-03T12:19:04.960" LastActivityDate="2014-02-03T12:19:04.960" Title="What are the legal requirements for me to purchase an airplane that I will provide instruction in?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;aircraft-ownership&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1453" PostTypeId="2" ParentId="1402" CreationDate="2014-01-30T21:21:12.067" Score="6" Body="&lt;p&gt;I agree with &lt;a href=&quot;https://aviation.stackexchange.com/a/1404/391&quot;&gt;Lnafziger&lt;/a&gt;'s post with the advisory circular definition of holding out versus common carriage. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;AC120-12A - Private Carriage Versus Common Carriage of Persons or&#xA;  Property contains guidance that can be used to help determine whether&#xA;  or not an operation falls under common carriage. Take a look at it for&#xA;  specific examples, but the &quot;plain language&quot; version is:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Common Carriage: A carrier becomes a common carrier when it &quot;holds&#xA;  itself out&quot; to the public, or to a segment of the public.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Holding Out: A carrier is holding out when they represent themselves&#xA;  as willing to furnish transportation within the limits of its&#xA;  facilities to any person who wants it.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There are lots of ways to &quot;hold out&quot;, but the basic idea is if someone&#xA;  in the general public comes to you and asks you to fly them and you&#xA;  agree, you are probably holding out. Any form of advertising&#xA;  demonstrates a clear sign that you are holding out. There are also&#xA;  other activities that qualify, so look over the AC if you have further&#xA;  questions, and if that doesn't answer it your best bet is to contact&#xA;  an aviation lawyer. You could also contact your local FSDO with&#xA;  questions.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;HOWEVER, and this is the big but that can get you into a world of trouble, just because you have a commercial pilots license and yes you &lt;em&gt;can&lt;/em&gt; get legally paid to fly you really &lt;strong&gt;cannot&lt;/strong&gt; carry passengers for compensation. Typically a commercial pilot can have a job like flying skydivers, crop dusting, aerial photography and (with an instructors certificate) provide flight instruction for compensation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There seems to be a big misconception though that a person can just get a commercial pilots license and take their friends up for compensation. This is false. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/7B29C0FFCE0C430A86256EDF00478339?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 1.1&lt;/a&gt; clearly defines commercial operator as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Commercial operator means a person who, for compensation or hire,&#xA;  engages in the carriage by aircraft in air commerce of persons or&#xA;  property, other than as an air carrier or foreign air carrier or under&#xA;  the authority of Part 375 of this title. Where it is doubtful that an&#xA;  operation is for &quot;compensation or hire&quot;, the test applied is whether&#xA;  the carriage by air is merely incidental to the person's other&#xA;  business or is, in itself, a major enterprise for profit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In fact, inside of &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%20120-12A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC120-12A&lt;/a&gt; itself it even states under Part I:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In summary, persons intending to conduct only private operations in&#xA;  support of other business should look cautiously at any proposal for&#xA;  revenue-generating flights which most likely would require&#xA;  certification as an air carrier.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So while you can fly for hire, you cannot carry passengers or property because then you are acting as a commercial operator. You can work for a commercial operator with that license although for 135 you will need 1200hrs to be PIC. You can do other for hire flying like carrying skydivers, crop dusting, banner towing or aerial photography though as perscribed in the only exceptions stated in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/6ed75326fa829948862572820066a936!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 119.1(e)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to fly with your friends you cannot charge them for your time. You could be flying to a business meeting and happen to be on the clock anyway but you cannot specifically charge for the transportation. What you also can do (even as a private pilot) is share costs. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2.5.1.8&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 61.113&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A private pilot may not pay less than the pro rata share of the&#xA;  operating expenses of a flight with passengers, provided the expenses&#xA;  involve only fuel, oil, airport expenditures, or rental fees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To summarize a commercial pilots license allows you to fly for hire but does not allow you to act as a commercial operator and carry persons or property &lt;strong&gt;other than as an air carrier&lt;/strong&gt;. You can work for someone who has that certificate but you can't just rent or buy a plane and charge a passenger for your time as pilot legally even as a commercial pilot. You can only split costs with them just like you could as a private pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/avlaw/186346-1.html?redirected=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Traps For The Unwary: Business Flying And The &quot;Compensation Or Hire&quot; Rule&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have seen some mentions of trying to get away with Part 91 Subpart K as well. &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/91.1005&quot; rel=&quot;nofollow noreferrer&quot;&gt;§ 91.1005 Prohibitions and limitations.&#xA;(a) Except as provided in § 91.321 or § 91.501, no owner may carry persons or property for compensation or hire on a program flight.&lt;/a&gt; &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/91.501&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.501&lt;/a&gt;, however, is going to say this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Operations that may be conducted under the rules in this subpart&#xA;  instead of those in parts 121, 129, 135, and 137 of this chapter when&#xA;  common carriage is not involved, include— &#xA;  (1) Ferry or training&#xA;  flights; &#xA;  (2) Aerial work operations such as aerial photography or&#xA;  survey, or pipeline patrol, but not including fire fighting&#xA;  operations;&#xA;  (3) Flights for the demonstration of an airplane to&#xA;  prospective customers when &lt;strong&gt;no charge&lt;/strong&gt; is made except for those&#xA;  specified in paragraph (d) of this section; &#xA;  (4) Flights conducted by&#xA;  the operator of an airplane for his personal transportation, or the&#xA;  transportation of his guests when &lt;strong&gt;no charge, assessment, or fee&lt;/strong&gt; is&#xA;  made for the transportation; &#xA;  (5) Carriage of officials, employees,&#xA;  guests, and property of a company on an airplane operated by that&#xA;  company, or the parent or a subsidiary of the company or a subsidiary&#xA;  of the parent, when the carriage is within the scope of, and&#xA;  incidental to, the business of the company (other than transportation&#xA;  by air) and &lt;strong&gt;no charge, assessment or fee&lt;/strong&gt; is made for the carriage in&#xA;  excess of the cost of owning, operating, and maintaining the airplane,&#xA;  except that no charge of any kind may be made for the carriage of a&#xA;  guest of a company, when the carriage is not within the scope of, and&#xA;  incidental to, the business of that company; &#xA;  (6) The carriage of&#xA;  company officials, employees, and guests of the company on an airplane&#xA;  operated under a time sharing, interchange, or joint ownership&#xA;  agreement as defined in paragraph (c) of this section; &#xA;  (7) The carriage of property (other than mail) on an airplane operated by a&#xA;  person in the furtherance of a business or employment (other than&#xA;  transportation by air) when the carriage is within the scope of, and&#xA;  incidental to, that business or employment and &lt;strong&gt;no charge, assessment,&lt;/strong&gt;&#xA;  &lt;strong&gt;or fee&lt;/strong&gt; is made for the carriage other than those specified in&#xA;  paragraph (d) of this section; &#xA;  (8) The carriage on an airplane of an athletic team, sports group, choral&#xA;  group, or similar group having a common purpose or objective when there is&#xA;  &lt;strong&gt;no  charge, assessment, or fee of any kind&lt;/strong&gt; made by any person for that &#xA;  carriage; &#xA;  and (9) The carriage of persons on an airplane operated by a person in the&#xA;  furtherance of a business other than transportation by air for the&#xA;  purpose of selling them land, goods, or property, including franchises&#xA;  or distributorships, when the carriage is within the scope of, and&#xA;  incidental to, that business and no charge, assessment, or fee is made&#xA;  for that carriage. (10) Any operation identified in paragraphs (b)(1)&#xA;  through (b)(9) of this section when conducted— (i) By a fractional&#xA;  ownership program manager, or (ii) By a fractional owner in a&#xA;  fractional ownership program aircraft operated under subpart K of this&#xA;  part, except that a flight under a joint ownership arrangement under&#xA;  paragraph (b)(6) of this section may not be conducted. For a flight&#xA;  under an interchange agreement under paragraph (b)(6) of this section,&#xA;  the exchange of equal time for the operation must be properly&#xA;  accounted for as part of the total hours associated with the&#xA;  fractional owner's share of ownership.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you think that you can fly as a &quot;private carrier&quot; under Part 91 and charge for it and not be found as needing a 135 air carrier certificate (or maybe 121, 125, etc..) you are in for a world of hurt. &lt;a href=&quot;https://www.aopa.org/News-and-Video/All-News/1995/February/1/Pilot-Counsel.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA Legal Counsel&lt;/a&gt; Offers a nice write up on some of the differences between having a CPL and being a commercial operator. The exceptions to this rule are the ones in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/6ed75326fa829948862572820066a936!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;119.1(e)&lt;/a&gt; as mention before (aerial photography, etc..).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why &quot;&lt;em&gt;private carriage&lt;/em&gt;&quot; does &lt;strong&gt;NOT&lt;/strong&gt; relieve you of getting an air carrier certificate. Even if you are found to be private carriage &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f2a3b3a3a1be0b69eb233dd2721c77d0&amp;amp;node=14:3.0.1.1.5.2.1.2&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 119.23(b)&lt;/a&gt; clearly states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Each person who conducts noncommon carriage (except as provided in §91.501(b) of this chapter) or private carriage operations for&#xA;  compensation or hire with airplanes having a passenger-seat&#xA;  configuration of less than 20 seats, excluding each crewmember seat,&#xA;  and a payload capacity of less than 6,000 pounds shall—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Comply with the certification and operations specifications&#xA;  requirements in subpart C of this part;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Conduct those operations in accordance with the requirements of&#xA;  part 135 of this chapter, except for those requirements applicable&#xA;  only to commuter operations; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Be issued operations specifications in accordance with those&#xA;  requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Guess what &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=f2a3b3a3a1be0b69eb233dd2721c77d0&amp;amp;n=14y3.0.1.1.5&amp;amp;r=PART&amp;amp;ty=HTML#14:3.0.1.1.5.3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Subpart C&lt;/a&gt; of 119 is going to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§119.33   General requirements. (a) A person may not operate as a direct air carrier unless that person—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Is a citizen of the United States;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Obtains an Air Carrier Certificate; &lt;em&gt;and etc..&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So any notion that you can fly for compensation other than exceptions in 119.1(e) is &lt;strong&gt;FALSE&lt;/strong&gt; unless you also possess the appropriate operating certificate.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-01-31T18:01:01.823" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1454" PostTypeId="1" AcceptedAnswerId="1459" CreationDate="2014-01-30T21:58:13.280" Score="12" ViewCount="3850" Body="&lt;p&gt;Is it possible to rent a float plane with a private pilot's license?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying floats is one of the main attractions for me to learn to fly.  However, after some searching on the internet I can only find wheeled aircraft that are available for rent in my area.  Am I missing something?  Are there flying clubs or partnerships that have float planes available?  I would love to fly floats but owning a seaplane is not in the cards for me at this point in my life.&lt;/p&gt;&#xA;" OwnerUserId="762" LastEditorUserId="69" LastEditDate="2014-01-30T23:24:06.057" LastActivityDate="2019-03-28T15:46:02.883" Title="Where can I rent a float plane?" Tags="&lt;usa&gt;&lt;seaplane&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1455" PostTypeId="2" ParentId="1449" CreationDate="2014-01-30T22:23:42.000" Score="21" Body="&lt;p&gt;First, you have to remember on some configurations, the lower stages of flap will mostly add drag and very little lift. Sometimes that extra notch of full flaps is only there to change the camber of the wing to add a bit of a nose down attitude to help with visibility on landing. Both are items you do not require on takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, when selecting flaps for take-off there are two things to consider: runway length and obstacles to clear after the runway:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Runway Length&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally when lowering flaps your $V_{\text{mu}}$ (the speed at which you become airborne, “minimum unstick speed”) will decrease. This  means a shorter runway for normal stages of flaps. As you continue to add more flaps your $V_{\text{mu}}$ will be lower, but because of the added drag, which decreases acceleration,  it will actually take a longer distance to reach that lower $V_{\text{mu}}$. There is a sweet spot in-between, though. “Take-off Flaps” is not always designed to give you the shortest takeoff roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Obstacle Clearance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that is because once airborne, the more flaps you have deployed, the higher the drag, the less excess thrust available, thus the less you can climb. Simply put, you are now flying at a low speed and barely climbing. Not a good idea if there are tall trees waiting for you at the end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It would be illegal&lt;/strong&gt;  to take-off on full flaps if:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;POH says it is prohibited,or&lt;/li&gt;&#xA;&lt;li&gt;For commercial flying, if the flap setting does not provide the minimum required gross obstacle clearance climb gradient (depending on the type of operation and number of engines, between 2.4%-3.0% ).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2015-03-13T07:24:01.873" LastActivityDate="2015-03-13T07:24:01.873" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1456" PostTypeId="1" CreationDate="2014-01-30T22:42:57.503" Score="12" ViewCount="35974" Body="&lt;p&gt;Is there a map I can refer to in order to pick up the correct frequency for VFR flight following while enroute? I know I can request a frequency from ATC as I depart, but what if I want to fly around and do sight seeing, practice maneuver for my checkride etc. for a while, then pick up flight following for the remainder of the trip?&lt;/p&gt;&#xA;" OwnerUserId="526" LastEditorUserId="62" LastEditDate="2014-01-30T23:01:07.897" LastActivityDate="2021-03-29T20:26:12.687" Title="On a chart, how can I find the frequency for flight following?" Tags="&lt;air-traffic-control&gt;&lt;flight-training&gt;&lt;usa&gt;&lt;visual-flight-rules&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1457" PostTypeId="2" ParentId="1456" CreationDate="2014-01-30T22:46:46.510" Score="6" Body="&lt;p&gt;In the United States, you can consult the VFR Sectional Chart and look for the frequency box located near a terminal area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vi2Vu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise you'll need to consult the Airport Facility Directory for the region your are flying to find a ARTCC (Center) frequency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/twmD5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="423" LastEditDate="2014-01-30T22:56:47.713" LastActivityDate="2014-01-30T22:56:47.713" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1458" PostTypeId="2" ParentId="1456" CreationDate="2014-01-30T22:59:34.467" Score="3" Body="&lt;p&gt;I assume you're in the US? If you got flight following when you departed from a controlled field then ATC should tell you if you need to change frequency, unless of course they have to stop providing you the service because of workload or whatever.&lt;/p&gt;&#xA;&lt;p&gt;In general, flight following is provided by the nearest TRACON or ARTCC, so you can look in at least three places, two of which are maps:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The VFR chart, if you're near a controlled field, which shows the TRACON frequencies&lt;/li&gt;&#xA;&lt;li&gt;The IFR en route chart, which shows the ARTCC frequency for your general area even if you're not close to a controlled field&lt;/li&gt;&#xA;&lt;li&gt;The Chart Supplement, if you're near a controlled field&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2021-03-29T20:26:12.687" LastActivityDate="2021-03-29T20:26:12.687" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1459" PostTypeId="2" ParentId="1454" CreationDate="2014-01-30T23:01:07.843" Score="11" Body="&lt;p&gt;The &lt;a href=&quot;http://www.seaplanes.org/spa/&quot;&gt;Seaplane Pilot's Association&lt;/a&gt; publishes a &lt;a href=&quot;http://www.seaplanes.org/mambo/index.php?option=com_content&amp;amp;task=view&amp;amp;id=41&quot;&gt;Water Landing Directory&lt;/a&gt; that includes seaplane facilities and flight planning maps for cross countries. This lists facilities that offer seaplane rental's. There is a discounted price on the directory for SPA members.&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-01-30T23:01:07.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1460" PostTypeId="1" AcceptedAnswerId="1463" CreationDate="2014-01-31T02:49:00.710" Score="12" ViewCount="1521" Body="&lt;p&gt;I'm learning ATC and one question is worrying me..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do I tell a pilot to exit a hold and continue inbound...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eg: pilot has entered hold and done one orbit.&#xA;and started the second, &#xA;and I want the aircraft to turn again 180 degree on inbound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically how do I tell an aircraft to break out the stack, and continue flight plan.&lt;/p&gt;&#xA;" OwnerUserId="42" LastEditorUserId="69" LastEditDate="2014-02-01T13:48:04.570" LastActivityDate="2014-02-15T14:43:57.233" Title="How do I clear an aircraft to exit a hold?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;holding&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1461" PostTypeId="2" ParentId="1460" CreationDate="2014-01-31T03:22:53.460" Score="0" Body="&lt;p&gt;When you issue the hold you should give them an expect further clearance time, so that's one way to imply that they will be exiting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually I hear ATC say &quot;report procedure turn inbound&quot; or in the case of your question, &quot;report inbound to [the fix]&quot; right after the aircraft turns outbound the second/third/nth time. When the pilot reports inbound, ATC might say &quot;pass [hold fix] at or above [altitude],&quot; but definitely &quot;proceed on course/you're clear for the approach.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry if my terminology is off, I haven't flown IFR in a while.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-31T03:22:53.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1462" PostTypeId="2" ParentId="1460" CreationDate="2014-01-31T03:30:40.147" Score="1" Body="&lt;p&gt;Simply clear the aircraft to a new fix or provide vectors, depending on the situation. There's no need to explicitly state that they should exit the hold. If you'd like them to continue as per the flight plan, you can use something like (at least in the US):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOVEMBER 368 JULIET ECHO, CLEARED TO (destination) VIA LAST ROUTING CLEARED [(further instructions)].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0406.html&quot; rel=&quot;nofollow&quot;&gt;FAA AIM, paragraph 4-6-2&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-02-15T14:43:57.233" LastActivityDate="2014-02-15T14:43:57.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1463" PostTypeId="2" ParentId="1460" CreationDate="2014-01-31T03:50:06.513" Score="14" Body="&lt;p&gt;This depends on what exactly you want the aircraft to do:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Immediately depart the hold and fly directly to another fix:&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 cleared to 'clearance limit' via direct 'fix' and then as previously filed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Immediately depart the hold and fly an assigned heading:&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 Cleared to 'clearance limit' via radar vectors. Fly heading 'heading'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Proceed to another fix after passing the holding point inbound:&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 After 'holding fix', cleared to 'clearance limit' via direct 'fix' and then as previously filed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Fly the published approach after passing the holding point inbound:&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 Maintain 'altitude' until 'holding fix', cleared 'approach name'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;Altitude&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Lastly, add the altitude to any of the above clearances if it is different than the current altitude by adding a climb/descend and maintain  'altitude' clearance. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-01T10:36:08.560" LastActivityDate="2014-02-01T10:36:08.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1464" PostTypeId="1" AcceptedAnswerId="1465" CreationDate="2014-01-31T04:21:42.270" Score="21" ViewCount="8889" Body="&lt;p&gt;For example, let's say we have an Airbus A330 in front, which has just landed, well past the threshold and looks like it's going to be alright. Next in line to land is a small general aviation aircraft, such as a Cessna 172.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it looks like there's little to no risk of the two aircraft colliding and there's already more than enough space to stop the aircraft, so why can't a controller use their judgement to be able to clear the aircraft behind to land? It seems like that it's a waste of time when you know that there's going to be more than ample time for the previous aircraft to turn off, so what's the problem with that?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2020-03-07T05:55:13.633" Title="Why can't aircraft be cleared to land before the preceding aircraft turns off the runway?" Tags="&lt;air-traffic-control&gt;&lt;safety&gt;&lt;runways&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1465" PostTypeId="2" ParentId="1464" CreationDate="2014-01-31T04:37:55.747" Score="17" Body="&lt;p&gt;Actually, the FAA doesn't always require the preceding airplane to clear the runway if they have the required separation unless it is dark (when it is very hard to visually estimate distances).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0310.html&quot;&gt;FAA Air Traffic Control Order Section 10. Arrival Procedures and Separation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3-10-6. ANTICIPATING SEPARATION&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Landing clearance to succeeding aircraft in a landing sequence need&#xA;  not be withheld if you observe the positions of the aircraft and&#xA;  determine that prescribed runway separation will exist when the&#xA;  aircraft crosses the landing threshold. Issue traffic information to&#xA;  the succeeding aircraft if a preceding arrival has not been previously&#xA;  reported and when traffic will be departing prior to their arrival.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE- “American Two Forty-Five, Runway One-Eight, cleared to land,&#xA;  number two following a United Seven-Thirty-Seven two mile final.&#xA;  Traffic will depart prior to your arrival.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“American Two Forty-Five, Runway One-Eight, cleared to land. Traffic&#xA;  will depart prior to your arrival.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- Landing sequence number is optional at tower facilities where&#xA;  the arrival sequence to the runway is established by the approach&#xA;  control.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. Anticipating separation must not be applied when conducting LUAW&#xA;  operations, except as authorized in paragraph 3-10-5b2. Issue&#xA;  applicable traffic information when using this provision.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE- “American Two Forty-Five, Runway One-Eight, cleared to land.&#xA;  Traffic will be a Boeing Seven-Fifty-Seven holding in position.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the separation is specified in the same document:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3-10-3. SAME RUNWAY SEPARATION&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Separate an arriving aircraft from another aircraft using the same&#xA;  runway by ensuring that the arriving aircraft does not cross the&#xA;  landing threshold until one of the following conditions exists or&#xA;  unless authorized in para 3-10-10, Altitude Restricted Low Approach.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The other aircraft has landed and is clear of the runway. (See FIG 3-10-1.) Between sunrise and sunset, if you can determine distances by&#xA;  reference to suitable landmarks and the other aircraft has landed, it&#xA;  need not be clear of the runway if the following minimum distance from&#xA;  the landing threshold exists:&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(a) When a Category I aircraft is landing behind a Category I or II-&#xA;  3,000 feet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) When a Category II aircraft is landing behind a Category I or II-&#xA;  4,500 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-31T04:37:55.747" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="1466" PostTypeId="1" AcceptedAnswerId="1467" CreationDate="2014-01-31T05:24:04.840" Score="11" ViewCount="4240" Body="&lt;p&gt;I know there has been some cases where a flight instructor is sued after a current or former student does something that gets themselves (the student) killed or causes damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that there have been cases where a flight instructor has been acquitted by proving that they took &lt;em&gt;due care&lt;/em&gt; in their flight instruction, and the accident was not a result of poor instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What specifically would a prudent flight instructor do to ensure they are keeping detailed enough records to prove that they are providing adequate instruction and that a resulting accident would not be due to poor instruction?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the records a CFI is legally required to keep, and what are the records they should keep in addition to that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is in context of CFIs in the United States.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="69" LastEditDate="2014-02-03T12:19:41.587" LastActivityDate="2014-02-03T12:19:41.587" Title="What records should a CFI keep to prove they took due care in the quality of their instruction?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;usa&gt;&lt;liability&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1467" PostTypeId="2" ParentId="1466" CreationDate="2014-01-31T07:03:52.893" Score="5" Body="&lt;p&gt;Have a well defined syllabus, and then a daily activity sheet where you write down the lesson you did, the time it took, and how the student performed. If anything peculiar happens, make a note. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a well-written lesson binder too. Even if you don't need to use the binder to teach a lesson (like steep turns, that's not really much of a ground lesson), have it in there anyway to show that you know what you're talking about. If you have a page that only says &quot;Teach steep turns&quot; and a lawyer gets a hold of it, there's nothing to prove that you actually know how to teach steep turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AS for legally required records:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You must sign the logbook of anyone you have given flight or ground training.&lt;/li&gt;&#xA;&lt;li&gt;You must maintain a record of the following:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The date and name of each person whose logbook/student pilot certificate you endorse for solo flight privileges (I keep a record of &lt;em&gt;every&lt;/em&gt; endorsement).&lt;/li&gt;&#xA;&lt;li&gt;The date and name of each person you endorse for a knowledge/practical test, and the kind, date, and result of the test.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You must keep the records for at least 3 years.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-01-31T07:03:52.893" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1469" PostTypeId="2" ParentId="1452" CreationDate="2014-01-31T08:38:00.320" Score="10" Body="&lt;p&gt;The requirement for 100 hour inspections is probably the biggest regulatory/legal item you'll come up against.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for other regulatory items, there's some fuzz on the subject of whether providing the aircraft used in flight instruction and receiving compensation makes that aircraft &quot;for hire&quot; and triggers all the other FARs that come into play when operating an aircraft &quot;for hire&quot; (like the requirement for a working landing light, or the requirement for approved flotation devices if you're beyond power-off gliding distance from shore).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could argue pretty convincingly either way (and there are some convincing arguments on the internet both ways), but I've not seen anything from the FAA that I would call definitive.&lt;br&gt;&#xA;The safe interpretation would be to treat the operation as &quot;for hire&quot; unless you can get something in writing from your local FSDO or the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/contacts/&quot;&gt;FAA Chief Counsel's office&lt;/a&gt; saying that it isn't.&lt;br&gt;&#xA;(Honestly the additional regulatory burden is really not that onerous - I mean don't you want a working landing light and life jackets &lt;em&gt;anyway&lt;/em&gt;?)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as liability goes you're going to want to talk to an aviation insurance broker about at least three kinds of policies:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Insurance for yourself, as a CFI.&lt;/li&gt;&#xA;&lt;li&gt;Insurance for the aircraft, as a rental aircraft/aircraft used for instruction.&lt;/li&gt;&#xA;&lt;li&gt;&quot;Renter's Insurance&quot; for your students.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The first two cover you.  The third protects your students in case they damage the aircraft on a solo flight: your insurance company may try to recoup their loss from the student responsible for the damages (&lt;a href=&quot;http://en.wikipedia.org/wiki/Subrogation#Indemnity_insurer.27s_subrogation_rights&quot;&gt;subrogation&lt;/a&gt;), and a (good) renter's insurance policy would cover such an occurrence, as well as paying for any &lt;em&gt;other&lt;/em&gt; things which may have been damaged like airport lighting, parked aircraft, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These insurance policies may also have additional requirements above and beyond those in the FARs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on your personal assets and the level of risk you're comfortable with an umbrella liability policy - either through your aviation broker or another broker/agent - may also be something worth considering (if you have such a policy written by someone who does not specialize in aviation make certain the policy does not have an aviation exclusion).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-01-31T08:38:00.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1470" PostTypeId="2" ParentId="1397" CreationDate="2014-01-31T12:22:24.780" Score="24" Body="&lt;p&gt;Engine location performance-affecting factors:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1. Mounted in the wing root&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;low asymetric yaw on engine failure, less rudder required: less drag&lt;/li&gt;&#xA;&lt;li&gt;no engine pods: less parasitic drag&lt;/li&gt;&#xA;&lt;li&gt;engines closer to CG, less downforce needed from the tail:  less drag&lt;/li&gt;&#xA;&lt;li&gt;very little reverse thrust available&lt;/li&gt;&#xA;&lt;li&gt;Little space for high-bypass-ratio engines&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. Mounted in pods under the wing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;high asymetric yaw on engine failure requires larger rudder: drag penalties&lt;/li&gt;&#xA;&lt;li&gt;engines provide bending relief on the wing, allowing better wing design (thinner wings): less drag&lt;/li&gt;&#xA;&lt;li&gt;at high incidence angles the pods can prevent spanwise flow: less drag and better stall characteristics &lt;/li&gt;&#xA;&lt;li&gt;full thrust can impose a large, undesirable, pitch up moment (think stall recovery)&lt;/li&gt;&#xA;&lt;li&gt;less freedom in roll on cross-wind landings&lt;/li&gt;&#xA;&lt;li&gt;Location ahead of the wing's elastic line helps to dampen flutter&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. Mounted inside the tail or on pods on the rear fuselage&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;low asymetric yaw on engine failure, less rudder required: less drag&lt;/li&gt;&#xA;&lt;li&gt;wing design is freed from the need to accomodate engines, allows for more complex wing designs: better performance throughout the flight envelope&lt;/li&gt;&#xA;&lt;li&gt;heavy engines so far aft of the fuselage require wings mounted further aft, and a higher tail to support that: more drag&lt;/li&gt;&#xA;&lt;li&gt;Lower landing gear required, especially in case of short fuselages&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's about what I can come up from memory, maybe someone can merge all answers into a comunity wiki kinda post..&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="511" LastEditDate="2016-02-26T21:45:06.150" LastActivityDate="2016-02-26T21:45:06.150" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1471" PostTypeId="1" CreationDate="2014-01-31T12:48:21.597" Score="2" ViewCount="109" Body="&lt;p&gt;In &lt;em&gt;As the Pro Flies&lt;/em&gt;, John R. Hoyt writes (pages 41-42):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Suppose we have to land in high, gusty winds. That's what happened to&#xA;  Pilot Z, who once landed his plane during such conditions with his&#xA;  flaps down. After the wheels were on the runway he relaxed, never&#xA;  realizing that a plane is not landed until the switches are cut.&#xA;  Because he still had airspeed and because full flaps lowered the&#xA;  take-off speed, a small gust of wind was all that he needed to begin&#xA;  flying again. The additional lift was enough to raise him 10 feet from&#xA;  the runway, and at that point he ran out of gust, a condition aptly&#xA;  described as dis-gusted. He would have dropped back on the runway, had&#xA;  not an alert co-pilot opened the throttles and saved both the day and&#xA;  the landing gear.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He goes on to state how much flap should be used in what conditions, and then he finishes with this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let us then &lt;em&gt;raise&lt;/em&gt; the flaps in gusty or crosswinds as soon as the&#xA;  wheels touch down. To wait until it is time to taxi doesn't help slow&#xA;  the plane very much, and flaps do constitute a hazard in gusts.&#xA;  Besides, it is surprising how much a small pebble costs when it goes&#xA;  through a flap.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is he right? Should flaps be raised immediately after touchdown in gusty conditions?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="64" LastEditDate="2015-06-26T17:08:04.147" LastActivityDate="2015-06-26T17:08:04.147" Title="Raising flaps on touchdown in gusty conditions" Tags="&lt;landing&gt;&lt;flaps&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="1" ClosedDate="2014-02-01T03:29:23.793" ContentLicense="CC BY-SA 3.0" />
  <row Id="1473" PostTypeId="1" CreationDate="2014-01-31T14:23:24.583" Score="22" ViewCount="62510" Body="&lt;p&gt;How do I contact a Flight Service Station (FSS) in the United States in order to receive weather information or open a flight plan after I've already departed.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="69" LastEditDate="2014-01-31T15:45:15.583" LastActivityDate="2018-01-02T04:22:05.757" Title="How do I contact Flight Service while in flight?" Tags="&lt;usa&gt;&lt;radio-communications&gt;&lt;fss&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1474" PostTypeId="2" ParentId="1436" CreationDate="2014-01-31T15:14:03.800" Score="5" Body="&lt;p&gt;One thing that comes into my mind is the winglets (when present on newer aircraft). Airbus uses those that are triangular wingtip fence whereas boeing uses the blended winglet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the shape of the nose can give you an indication. On Boeing they are more sharp and protruded whereas on airbus the design is &quot;softer&quot; and more rounded..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check pics of a 737 and a A319 and you will notice the difference&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="258" LastEditDate="2014-01-31T15:45:51.887" LastActivityDate="2014-01-31T15:45:51.887" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1475" PostTypeId="2" ParentId="1446" CreationDate="2014-01-31T15:18:32.420" Score="6" Body="&lt;p&gt;Although tyres can wear out &quot;pretty fast&quot; with numerous landings however as long as the carcass is in good condition then the tyre will go for a retread rather than be discarded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So from a purely economic point of view I suspect a retread is the cheapest option rather than trying to develop elaborate systems to extend the life of the tread. The other issues I can see with spin up motors is lack of space and temperatures. There is very little room inside a wheel rim for any motors, they are filled with multi-plate disc brakes. The brakes get very hot when braking and would be a very harsh environment for any motor. So far simpler and cheaper to retread the tyre when it starts to get worn out.&lt;/p&gt;&#xA;" OwnerUserId="769" LastActivityDate="2014-01-31T15:18:32.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1477" PostTypeId="1" CreationDate="2014-01-31T16:08:42.860" Score="13" ViewCount="1598" Body="&lt;p&gt;Can my training in a Sport aircraft with a Sport instructor be used to fulfill the requirements to become a Private Pilot?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, assume I've started my training to be a Sport Pilot, but decided I'd rather be a Private Pilot.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="12220" LastEditDate="2016-04-04T13:09:57.553" LastActivityDate="2016-04-04T13:09:57.553" Title="Can hours logged training to be a Sport Pilot apply toward the Private Pilot Certificate?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1478" PostTypeId="2" ParentId="1477" CreationDate="2014-01-31T16:56:56.327" Score="9" Body="&lt;p&gt;Absolutely, you can log just about any flight time in an aircraft!   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The definition of flight time is in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/A16147FC43C4F9B286257A9500451B45?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 1.1&lt;/a&gt; and says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Flight time&lt;/strong&gt; means:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Pilot time that commences when an aircraft moves under its own&#xA;  power for the purpose of flight and ends when the aircraft comes to&#xA;  rest after landing; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For a glider without self-launch capability, pilot time that&#xA;  commences when the glider is towed for the purpose of flight and ends&#xA;  when the glider comes to rest after landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, the &lt;strong&gt;instruction&lt;/strong&gt; logged towards a sport pilot rating by a &lt;em&gt;flight instructor certificate with a sport pilot rating&lt;/em&gt; (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/7F4301528DF1D8DF862576C400578B2B?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.413&lt;/a&gt;) may not be used toward the requirements of the private pilot certificate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the instructor is a CFI certified under &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/1635CA05BE5D036C86256EE10063A4D5?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.181&lt;/a&gt; then the instruction may also be used towards your private pilot certificate but you will need to be proficient to the higher standards, which may require additional training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who already have their Sport Pilot Certificate, take a look at this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/28/what-does-a-sport-pilot-have-to-do-to-get-a-private-pilot-certificate&quot;&gt;What does a sport pilot have to do to get a private pilot certificate?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-01-31T17:31:28.080" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1479" PostTypeId="2" ParentId="1466" CreationDate="2014-01-31T18:09:14.017" Score="4" Body="&lt;p&gt;Our 141 school keeps records digitally, but before that we used curriculum binders.  Each flight in the course had its own lesson plan listing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The planned lesson time&lt;/li&gt;&#xA;&lt;li&gt;The actual lesson time&lt;/li&gt;&#xA;&lt;li&gt;The elements or maneuvers to be accomplished&lt;/li&gt;&#xA;&lt;li&gt;What level of proficiency the student would need to demonstrate on each element in order to be considered satisfactory&lt;/li&gt;&#xA;&lt;li&gt;A space for the student's actual proficiency level per element&lt;/li&gt;&#xA;&lt;li&gt;A space for remarks&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Once the flight was complete, after filling out the logbook, both the instructor and student would sign the lesson sheet.  When everything in the binder was PTS or better, the student could be endorsed for the checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the second half of your question, I just copied this directly from &lt;a href=&quot;https://aviation.stackexchange.com/a/1467/167&quot;&gt;StallSpin's excellent answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AS for legally required records:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;You must sign the logbook of anyone you have given flight or ground training.&lt;/li&gt;&#xA;  &lt;li&gt;You must maintain a record of the following:&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The date and name of each person whose logbook/student pilot certificate you endorse for solo flight privileges (I keep a record of&#xA;  &lt;em&gt;every&lt;/em&gt; endorsement).&lt;/li&gt;&#xA;  &lt;li&gt;The date and name of each person you endorse for a knowledge/practical test, and the kind, date, and result of the test.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;You must keep the records for at least 3 years.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even though the minimum is 3 years, I keep the records forever.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-01-31T18:09:14.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1480" PostTypeId="2" ParentId="1473" CreationDate="2014-01-31T18:36:50.590" Score="25" Body="&lt;p&gt;For filing and opening VFR flight plans, pushing back your ETA because of a delay, and a few more obscure things which you can find in section &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0401.html&quot; rel=&quot;noreferrer&quot;&gt;4-1-21 of the AIM&lt;/a&gt; you would contact Flight Service (addressed as &lt;em&gt;&quot;region Radio&quot;&lt;/em&gt; - e.g. &quot;New York Radio&quot; or &quot;Bridgeport Radio&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The universal flight service frequency is 122.2, and above 5000 feet you should be able to get someone on that frequency, but it's not guaranteed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yo can't raise someone on 122.2, or you're below 5000 feet, there are local Flight Service frequencies are listed on VORs as shown below. As a general rule if you can receive the VOR you can talk to Flight Service with the frequencies listed, and using these local frequencies helps avoid congestion on the universal frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f4dgc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f4dgc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(skyvector.com)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initial calls to Flight Service should take the form:&lt;br&gt;&#xA;&lt;code&gt;&amp;lt;Facility Name&amp;gt; Radio, Cessna 12345, 5 northeast of Hampton VOR&lt;/code&gt;&lt;br&gt;&#xA;(as above for Flight Watch, Who you're talking to (&quot;New York Radio&quot; in the example above), Who you are, and Where you are.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a little catch with Flight Service frequencies: If there is an &lt;code&gt;R&lt;/code&gt; after the frequency (as shown for 122.1 here) it is a receive-only frequency. You will talk to flight service on that frequency, but you will &lt;em&gt;listen&lt;/em&gt; to the VOR's audio channel to hear Flight Service's responses.&lt;br&gt;&#xA;When you call Flight Service using one of these frequencies make sure your nav radio is tuned to the VOR and the voice channel volume is up, and let them know which VOR you're listening to as opposed to your location.&lt;br&gt;&#xA;In this example if you were contacting Flight Service on 1221 the call would be &lt;code&gt;New York Radio, Cessna 12345, receiving on Hampton VOR&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For weather (giving PIREPs or asking for a weather report) you will also talk to Flight Service: There used to be a separate service (Flight Watch) and frequency for this, but weather-related tasks were consolidated into the general Flight Service frequency in late 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radio coverage and contact procedures are identical to what was mentioned above for dealing with flight plan stuff, but you should make it clear you're looking for weather updates (add &quot;requesting enroute weather&quot;) or that you want to give a PIREP (add &quot;With a pilot report&quot;) so the Flight Service Specialist on the other end of the radio knows what you're looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As weather is generally a localized phenomenon (and weather updates or PIREPs can take some time to relay) it is probably be a good idea to use the local flight service frequencies for weather-relatedrather than the universal 122.2 frequency to avoid congestion there, though I don't believe the FAA or Flight Service has issued any official guidance on this since Flight Watch was consolidated with the rest of Flight Service.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="14897" LastEditDate="2017-04-28T11:27:16.327" LastActivityDate="2017-04-28T11:27:16.327" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1481" PostTypeId="1" CreationDate="2014-01-31T19:13:34.627" Score="20" ViewCount="5125" Body="&lt;p&gt;I would like to use an iPad for preflight planning. Can I also use the iPad to check weather while I'm en route?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="97" LastEditDate="2014-03-19T07:33:25.980" LastActivityDate="2014-03-19T07:33:25.980" Title="Can I use cellular data to receive in-flight weather on my iPad?" Tags="&lt;faa-regulations&gt;&lt;flight-planning&gt;&lt;weather&gt;&lt;efb&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1482" PostTypeId="2" ParentId="1481" CreationDate="2014-01-31T19:27:42.783" Score="6" Body="&lt;h1&gt;I have never had much luck with cellular data in flight.&lt;/h1&gt;&#xA;&lt;p&gt;This might just be a function of the kinds of locations where I fly, but in my experience the connection is never good enough to get reliable weather information. Once in a while you might get an update, but I wouldn't count on it.&lt;/p&gt;&#xA;&lt;p&gt;A &lt;strong&gt;much&lt;/strong&gt; better option (if you can afford it) is &lt;a href=&quot;http://www.appareo.com/cat/primarymenu/products/stratus/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FIS-B&lt;/a&gt;, which has always worked reliably for me, especially when there really is weather out there (which is when you really need it to work).&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-01T18:59:08.293" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1483" PostTypeId="2" ParentId="1481" CreationDate="2014-01-31T19:31:41.333" Score="8" Body="&lt;p&gt;Unfortunately, in the US it is not permitted to use cellular service in flight because the FCC does not permit it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the bright side, the FCC just released a &lt;a href=&quot;http://transition.fcc.gov/Daily_Releases/Daily_Business/2013/db1121/DOC-324307A1.pdf&quot;&gt;press release&lt;/a&gt; which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;November 21st, 2013  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;STATEMENT OF CHAIRMAN TOM WHEELER ON FCC PROPOSAL TO INCREASE  CONSUMER ACCESS TO IN-FLIGHT MOBILE WIRELESS SERVICES&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Washington, D.C. – Chairman Tom Wheeler has issued the following&#xA;  statement:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“Today, we circulated a proposal to expand consumer access and choice&#xA;  for in-flight mobile  broadband. Modern technologies can deliver&#xA;  mobile services in the air safely and reliably, and the time is right&#xA;  to review our outdated and restrictive rules. I look forward to&#xA;  working closely with my colleagues, the FAA, and the airline industry&#xA;  on this review of new mobile opportunities for consumers.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;-FCC-&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, even if it might work at low altitudes, I would highly recommend against it if you are flying IFR.  I have seen videos of cell phones causing flight instruments to act erratically and they can cause major issues if the airplane isn't specifically certified for it.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-01-31T19:31:41.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1484" PostTypeId="2" ParentId="1481" CreationDate="2014-01-31T19:33:16.887" Score="2" Body="&lt;p&gt;Yes....ish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US up until recently the answer was an emphatic (FCC-mandated) NO, but the FCC &lt;a href=&quot;http://www.fcc.gov/guides/wireless-devices-airplanes&quot; rel=&quot;nofollow noreferrer&quot;&gt;is considering relaxing those rules&lt;/a&gt;, and if those rule changes go through you will be &lt;em&gt;legally&lt;/em&gt; able to use your iPad's cellular data connection in flight (provided the pilot in command deems it's not a hazard to the flight - so remember to tell yourself it's OK to use the iPad).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pretty much every CFI I've flown with has ignored this rule, and I'll admit to occasionally checking weather on my phone in flight too. It &lt;em&gt;sometimes&lt;/em&gt; works, but in my experience only at relatively low altitudes (I typically lose my cellular signal somewhere between 2500 and 3500 feet AGL. There are long, boring technical reasons for this but basically the way the cell site antennas are designed the signal covers the ground below where cell site is - there's not much signal aimed at the sky above it).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it only generally works on climb-out (when my pre-flight weather briefing is still &quot;fresh&quot;) or as I'm descending toward my destination (when I'm typically doing &lt;em&gt;other things&lt;/em&gt; like talking to controllers or trying to get the field's weather on the radio) I've not found it to be particularly useful to use cellular data to get in-flight weather / information updates.&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/1482/64&quot;&gt;As Steve said, ADS-B equipment is a much better (albeit more expensive) option.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-01-31T19:33:16.887" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1485" PostTypeId="2" ParentId="1481" CreationDate="2014-01-31T19:34:29.520" Score="12" Body="&lt;p&gt;&lt;em&gt;Can&lt;/em&gt; you? Yes, but service might be slow or spotty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;May you do so &lt;strong&gt;legally&lt;/strong&gt;?&lt;/em&gt; That probably depends. The FAA doesn't specifically prohibit the use of &lt;em&gt;any&lt;/em&gt; electronics in GA aircraft; they only state that &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.1.4.11&quot;&gt;under 14 CFR §91.21, those aboard an IFR aircraft can't operate electronic devices unless&lt;/a&gt; they are&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Portable voice recorders;&lt;/li&gt;&#xA;  &lt;li&gt;Hearing aids;&lt;/li&gt;&#xA;  &lt;li&gt;Heart pacemakers;&lt;/li&gt;&#xA;  &lt;li&gt;Electric shavers; or&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used.&lt;/strong&gt; [emphasis mine]&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's possibly questionable that you as the pilot are an authority on whether or not your devices will cause interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FCC, however, has &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=47:2.0.1.1.2.8.27.12&amp;amp;idno=47&quot;&gt;banned the use of cellular &lt;em&gt;phones&lt;/em&gt; in flight per 47 CFR §22.925&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whether or not that can be interpreted to apply to an iPad's 3G connection is pretty iffy.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-01-31T20:29:36.910" LastActivityDate="2014-01-31T20:29:36.910" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1486" PostTypeId="1" AcceptedAnswerId="1487" CreationDate="2014-01-31T20:52:36.087" Score="18" ViewCount="4988" Body="&lt;p&gt;When a pilot ejects, what happens to the ejection seat? Does the pilot stay in the seat until he lands, or does it get disconnected from the pilot somehow?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-02-03T11:34:26.390" LastActivityDate="2018-07-10T18:40:17.640" Title="What happens to the ejection seat after a pilot ejects?" Tags="&lt;military&gt;&lt;ejection-seat&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1487" PostTypeId="2" ParentId="1486" CreationDate="2014-01-31T22:17:42.503" Score="17" Body="&lt;p&gt;It depends on the seat. Most modern seats, including the ACES II system common in US Fighter Jets, fall away from the pilot at a pre-determined altitude. &lt;a href=&quot;http://science.howstuffworks.com/transport/flight/modern/ejection-seat2.htm&quot;&gt;[src]&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once out of the plane, a drogue gun in the seat fires a metal slug that pulls a small parachute, called a drogue parachute, out of the top of the chair. This slows the person's rate of descent and stabilizes the seat's altitude and trajectory. After a specified amount of time, an altitude sensor causes the drogue parachute to pull the main parachute from the pilot's chute pack. At this point, a seat-man-separator motor fires and the seat falls away from the crewmember. The person then falls back to Earth as with any parachute landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally, according to that link, this occurs at just over 100-200 feet above &lt;em&gt;ejection height&lt;/em&gt;. However, if you eject at high altitude, such as Captain Scott O'Grady did (26,000 ft), the seat will fall away on a sensor (either 10,000 or 18,000 feet, I don't recall which). The chute may open automatically, or if it is not set to at that height, you can then pull the chute manually, or wait until its set height to open.&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-01-31T22:17:42.503" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1488" PostTypeId="1" AcceptedAnswerId="1489" CreationDate="2014-02-01T02:08:03.293" Score="20" ViewCount="6651" Body="&lt;p&gt;FAR 61.57 says that you need to have completed three takeoffs and landings to a full stop in order to carry passengers at night. However, you only need three touch-and-gos in order to carry passengers during the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why the difference?&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some rationale for this?  Are full-stop landings considered safer during the night?&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="97" LastEditDate="2014-02-03T11:33:38.090" LastActivityDate="2014-02-03T11:33:38.090" Title="What's the reasoning for full-stop landings at night but touch-and-gos during the day for passenger currency?" Tags="&lt;faa-regulations&gt;&lt;currency&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1489" PostTypeId="2" ParentId="1488" CreationDate="2014-02-01T03:27:42.017" Score="19" Body="&lt;p&gt;There are three really convincing arguments I've heard for this - I'm not sure which is &quot;correct&quot; and explains the FAA's logic, but personally I suspect it's a little bit of each.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Argument 1:&lt;/strong&gt; Night landings are &quot;special&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A night landing is definitely different from a day landing - there's much less of a sight picture in the flare unless your airport is in a really bright area or you have a bright moon (and even then it's &quot;different&quot;).&lt;br&gt;&#xA;If all you're doing is tapping your wheels on the ground and quickly accelerating back to takeoff speed you're missing a lot of what a landing is - bringing the nose down, decelerating to a safe taxi speed, and leaving the runway under control.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which conveniently brings us to...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Argument 2:&lt;/strong&gt; &quot;You gotta learn how to taxi all over again!&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's something my instructor told me, and I didn't really understand what he meant until I was in the plane. Airports are &lt;strong&gt;&lt;em&gt;really dark&lt;/em&gt;&lt;/strong&gt; and it's hard to find your way around the taxiways at night. Personally I think a big part of this requirement is the &lt;em&gt;intent&lt;/em&gt; that you taxi off the runway and make your way back to the end to shoot another circuit. The hardest thing about my night training - aside from &lt;em&gt;finding the darn airports&lt;/em&gt; was taxiing around without getting lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Of course the regs don't say anything about &quot;Taxi off the runway&quot; - they just say &quot;full stop&quot;. You can satisfy the legal requirement with &quot;stop-and-go&quot; landings, but there's a nagging voice in my head that says you're not really &quot;getting current&quot; if that's all you do...)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Argument 3:&lt;/strong&gt; It slows your procedures down, which makes you safer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Touch-and-Go landings are kinda dangerous if you think about them - &lt;em&gt;Bring the plane in for a landing (which is already a lot of work). Now as soon as all your wheels are on the ground make a mental judgment as to whether you have enough runway to take off from given your current position &amp;amp; rolling start, if so retract your flaps to an appropriate takeoff setting, cram the throttle back in, and take off again.&lt;/em&gt;.&lt;br&gt;&#xA;When you look at them that way it's a bit odd that we have students do them (and there's more than one CFI around on the internet who says it's a lousy teaching tool).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding &quot;Oh yeah, and it's dark out!&quot; to that already difficult and dangerous procedure above is just &lt;em&gt;begging&lt;/em&gt; for an accident - especially in a retractable gear aircraft (gear lever, flaps lever, and what happens if you miss in the dark cockpit?).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-01T03:27:42.017" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1490" PostTypeId="1" AcceptedAnswerId="1491" CreationDate="2014-02-02T02:55:41.980" Score="6" ViewCount="3828" Body="&lt;p&gt;If a passenger shows up with an oxygen tank, can they bring it with them on the flight if their doctor says that it is medically necessary, or is a compressed tank of air considered hazardous material? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the regulations that cover this for flights operated under Part 91 and Part 135?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-02T03:49:49.713" LastActivityDate="2014-02-09T16:51:14.373" Title="Is it legal to carry medical oxygen on an aircraft for a passenger?" Tags="&lt;faa-regulations&gt;&lt;far-91&gt;&lt;far-135&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1491" PostTypeId="2" ParentId="1490" CreationDate="2014-02-02T03:58:20.490" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f1712fbee386b3367b9b1b09e556e881&amp;amp;node=14:3.0.1.1.11.2.3.19&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;FAR Part 135.91&lt;/a&gt; notes that medical oxygen containers - whether for the storage, generation, or dispensing of oxygen - must be:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;135.91.a.1.i Of an approved type or in conformity with the manufacturing, packaging, marking, labeling, and maintenance requirements of title 49 CFR parts 171, 172, and 173, except §173.24(a)(1)&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.1.ii When owned by the certificate holder, maintained under the certificate holder's approved maintenance program;&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.1.iii Free of flammable contaminants on all exterior surfaces; and&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.1.iv Appropriately secured.&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.2 When the oxygen is stored in the form of a liquid, the equipment must have been under the certificate holder's approved maintenance program since its purchase new or since the storage container was last purged.&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.3.i-ii When the oxygen is stored in the form of a compressed gas as defined in title 49 CFR 173.300(a) When owned by the certificate holder, it must be maintained under its approved maintenance program; and The pressure in any oxygen cylinder must not exceed the rated cylinder pressure.&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.4 The pilot in command must be advised when the equipment is on board, and when it is intended to be used.&lt;/p&gt;&#xA;&lt;p&gt;135.91.a.5 The equipment must be stowed, and each person using the equipment must be seated, so as not to restrict access to or use of any required emergency or regular exit, or of the aisle in the passenger compartment.&lt;/p&gt;&#xA;&lt;p&gt;135.91.b No person may smoke and no certificate holder may allow any person to smoke within 10 feet of oxygen storage and dispensing equipment carried under paragraph (a) of this section.&lt;/p&gt;&#xA;&lt;p&gt;135.91.c No certificate holder may allow any person other than a person trained in the use of medical oxygen equipment to connect or disconnect oxygen bottles or any other ancillary component while any passenger is aboard the aircraft&lt;/p&gt;&#xA;&lt;p&gt;135.91.d Paragraph (a)(1)(i) of this section does not apply when that equipment is furnished by a professional or medical emergency service for use on board an aircraft in a medical emergency when no other practical means of transportation (including any other properly equipped certificate holder) is reasonably available and the person carried under the medical emergency is accompanied by a person trained in the use of medical oxygen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Part 91 &lt;em&gt;does not&lt;/em&gt; seem to speak to medical oxygen&lt;/p&gt;&#xA;&lt;p&gt;Additionally, a &lt;a href=&quot;http://www.faa.gov/about/initiatives/cabin_safety/portable_oxygen/&quot; rel=&quot;noreferrer&quot;&gt;page on the FAA website&lt;/a&gt; notes that:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In the DOT final rule, section 382.133 generally requires that air carriers conducting passenger service must permit someone with a disability to use an FAA-approved portable oxygen concentrator (POC) on all flights (on aircraft originally designed to have a maximum passenger capacity of more than 19 seats) unless the device does not meet applicable FAA requirements for medical portable electronic devices (M-PED) and does not display a manufacturer’s label that indicates the device meets those FAA requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The page goes on to list approved oxygen containers. So, it seems that the FAA &lt;strong&gt;does not consider POCs to be hazardous, so long as they meet certain FAA approval standards&lt;/strong&gt;. (If you are asking about General Aviation requirements, I would assume an FAA-certified POC is okay to bring on a GA flight as well)&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-09T16:51:14.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1492" PostTypeId="1" AcceptedAnswerId="1500" CreationDate="2014-02-02T14:44:56.617" Score="12" ViewCount="2656" Body="&lt;p&gt;Say that I want to leave the city and go hunting somewhere.  Is it legal to bring a hunting rifle and ammunition with me in a private airplane? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, are there specific procedures to follow in order for it to be done safely? &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="167" LastEditDate="2014-02-02T21:13:54.650" LastActivityDate="2014-02-03T04:58:00.447" Title="Is it legal to bring (or allow someone else to bring) a firearm on a private flight?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;far-91&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1493" PostTypeId="1" AcceptedAnswerId="1498" CreationDate="2014-02-02T17:13:11.403" Score="29" ViewCount="86957" Body="&lt;p&gt;PAPI and VASI seem to be very similar in the the information they provide - i.e. are you on the glide slope or off it. Is there a functional difference between the two? If there is a difference, and one is superior to the other, is there a construction cost savings where an airport might chose one over the other?&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="1467" LastEditDate="2015-03-17T12:15:58.200" LastActivityDate="2020-03-15T00:19:10.263" Title="What's the functional difference between PAPI and VASI?" Tags="&lt;airport&gt;&lt;airport-lighting&gt;&lt;papi&gt;&lt;vasi&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1497" PostTypeId="2" ParentId="1493" CreationDate="2014-02-02T20:00:56.290" Score="17" Body="&lt;p&gt;The PAPI is functionally different from the VASI in terms of precision (hence the name!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Precision_approach_path_indicator&quot;&gt;Precision Approach Path Indicator&lt;/a&gt; (PAPI)&lt;/strong&gt; uses four sets of two lamps, placed next to each other to provide the pilot with 5 distinct levels of precision (&lt;code&gt;r&lt;/code&gt; = red; &lt;code&gt;w&lt;/code&gt; = white):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;code&gt;r r r r&lt;/code&gt; - below glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;r r r w&lt;/code&gt; - slightly below glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;r r w w&lt;/code&gt; - on glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;r w w w&lt;/code&gt; - slightly above glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;w w w w&lt;/code&gt; - above glideslope&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's also some degree of fading between red and white.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_approach_slope_indicator&quot;&gt;Visual Approach Slope Indicator&lt;/a&gt; (VASI)&lt;/strong&gt; uses four sets of two lamps in a box formation (two on top, two on bottom) to provide something more like 3 distinct sets of information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;code&gt;r r&lt;/code&gt;&lt;br&gt;&#xA;&lt;code&gt;r r&lt;/code&gt; - below glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;r r&lt;/code&gt;&lt;br&gt;&#xA;&lt;code&gt;w w&lt;/code&gt; - on glideslope&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;w w&lt;/code&gt;&lt;br&gt;&#xA;&lt;code&gt;w w&lt;/code&gt; - above glideslope&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The more vertical placement of the VASI lights is the origin of the mnemonic &quot;white over white, you're high as a kite; red over white, you're all right; Red over red, you're dead&quot;.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Operation&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;As far as operation and installation goes, I'm under the impression that both use the same two-lamp modules, configured with lenses, reflectors, and filters. Presumably the cost to install a VASI is lower, which is why they're much more common; alignment and maintenance is also likely to be cheaper as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, if one set of lamps in a PAPI is out of service, the entire unit is unusable. If a set of lamps in a VASI is out, the redundancy of the system means that it still can provide some information (albeit information that should be used with extreme caution).&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-02-02T20:42:34.857" LastActivityDate="2014-02-02T20:42:34.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1498" PostTypeId="2" ParentId="1493" CreationDate="2014-02-02T20:20:23.357" Score="26" Body="&lt;p&gt;A PAPI and a VASI are very similar in the the information they provide. The only functional differences between the VASI and PAPI is that the VASI has the red over the white, the PAPI the white actually goes to the right of the red, and the PAPI offers higher precision (or more glideslopes depending how you look at it a larger airliner with a high cockpit may elect to fly a slightly higher glidepath). The concept is the same though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;VASI&lt;/strong&gt; looks like this:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/SGBaq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Usage&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the saying goes,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Red over White, you're alright. (on glidepath)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Red over Red, you're dead. (too low)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;White over White, you're out-of-sight (too high)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ygdlp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;PAPI&lt;/strong&gt; like this:&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/7/7b/PAPI_Jersey_Airport.JPG&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A regular VASI only offers one glide slope and is designed for an aircraft where the cockpit isn't so high up. &lt;em&gt;However&lt;/em&gt;, there is a such thing as two-light PAPI, and a three-bar VASI. So either of them can really be tailored to fit the costs and types of aircraft flying to that airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a four-bar PAPI it is higher precision. Since the PAPI systems uses a narrower beam of light you must fly the glide path more precisely than the VASI to stay on the beam. The PAPI, with its extra lights, forewarns you when you are drifting from the desired glide path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pDUaF.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pDUaF.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://airportlightingcompany.com/images/PAPI-Diagram.gif&quot; rel=&quot;noreferrer&quot;&gt;airportlightingcompany.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So one red light would indicate slightly above glide slope, two and two would indicate the normal glide slope, and three red lights would indicate slightly below the glide slope on a 4-bar PAPI. A Three bar VASI works in similar fashion except there are only two glide paths with two reds being the lower, two whites the higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hnTiN.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="8282" LastEditDate="2019-02-16T21:23:13.620" LastActivityDate="2019-02-16T21:23:13.620" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1499" PostTypeId="1" AcceptedAnswerId="1503" CreationDate="2014-02-02T20:35:21.330" Score="4" ViewCount="11792" Body="&lt;p&gt;Everyone I know knows about DUATS and Flight Service weather briefers, but you almost never hear about TWEB and TIBS.  They have something to do with telephones and recorded weather information...are they the same thing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What's the difference between TWEBs and TIBS?  When is it appropriate to use each?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-02-03T04:51:22.727" LastActivityDate="2014-02-03T04:51:22.727" Title="What's the difference between TWEBs and TIBS?" Tags="&lt;flight-planning&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1500" PostTypeId="2" ParentId="1492" CreationDate="2014-02-02T21:48:06.753" Score="17" Body="&lt;p&gt;This is a tricky question, because it depends greatly on the laws of the locations you're flying to / from.  Here's a few of the things you have to take into consideration.&lt;/p&gt;&#xA;&lt;h1&gt;Transporting is generally ok&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/USCODE-2011-title18/html/USCODE-2011-title18-partI-chap44-sec926A.htm&quot; rel=&quot;noreferrer&quot;&gt;According to &lt;strong&gt;18 U.S.C. 926A&lt;/strong&gt;:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Notwithstanding any other provision of any law or any rule or&#xA;regulation of a State or any political subdivision thereof, any person&#xA;who is not otherwise prohibited by this chapter from transporting,&#xA;shipping, or receiving a firearm &lt;strong&gt;shall be entitled to transport a&#xA;firearm&lt;/strong&gt; for any lawful purpose &lt;strong&gt;from any place where he may lawfully&#xA;possess&lt;/strong&gt; and carry such firearm &lt;strong&gt;to any other place where he may&#xA;lawfully possess&lt;/strong&gt; and carry such firearm if, during such transportation&#xA;the firearm is &lt;strong&gt;unloaded&lt;/strong&gt;, and &lt;strong&gt;neither the firearm nor any ammunition&#xA;being transported is readily accessible&lt;/strong&gt; or is directly accessible from&#xA;the passenger compartment of such transporting vehicle: Provided, That&#xA;in the case of a vehicle without a compartment separate from the&#xA;driver's compartment the firearm or ammunition shall be contained in a&#xA;locked container other than the glove compartment or console.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;926A says nothing about the method of transport.  Most often it applies to motor vehicles, but it can just as easily apply to aircraft.  &lt;strong&gt;Therefore as long as you're ok to carry at the departure airport and the destination airport, federal law protects you in between.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Also, remember that 926A only protects you if the firearm is unloaded and locked / inaccessible.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;h1&gt;Ok, but can I bring my gun unloaded onto airport property, right?&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Not in a sterile area&lt;/h3&gt;&#xA;&lt;p&gt;You can't take a firearm into the sterile area of an airport.  &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=1ced5b69464d2621557bcad98c596051;rgn=div5;view=text;node=49:9.1.3.5.9;idno=49;cc=ecfr&quot; rel=&quot;noreferrer&quot;&gt;49 CFR 1540.5 defines a sterile area&lt;/a&gt; as:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Sterile area means a portion of an airport defined in the airport&#xA;security program that provides passengers access to boarding aircraft&#xA;and to which the access generally is controlled by TSA, or by an&#xA;aircraft operator under part 1544 of this chapter or a foreign air&#xA;carrier under part 1546 of this chapter, through the screening of&#xA;persons and property.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, if the terminal and the GA ramp are two separate entities, you're probably ok.  However, I've flown to some smaller airports where the GA ramp and the TSA terminal are right next to each other.  In these cases, you need to be careful that you don't get into the sterile area with your firearm.&lt;/p&gt;&#xA;&lt;h3&gt;Maybe not anywhere on the airport&lt;/h3&gt;&#xA;&lt;p&gt;Local law might prohibit the possession of a firearm anywhere on airport property, or the airport itself might ban firearms on their premises.  The only way to know is to check the specific airport you intend to fly out of.&lt;/p&gt;&#xA;&lt;h1&gt;What if I want to carry loaded?&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;The first thing to remember if you carry loaded is that &lt;strong&gt;18 USC 926A does not protect you&lt;/strong&gt;.  In that case, you're exercising the privileges of either open or concealed carry according to the laws of the departure and destination states.&lt;/p&gt;&#xA;&lt;h3&gt;Open carry&lt;/h3&gt;&#xA;&lt;p&gt;Some states prohibit open carry.  &lt;a href=&quot;http://www.youtube.com/watch?v=NQDJdurpUsA&quot; rel=&quot;noreferrer&quot;&gt;Others allow open carry when unloaded&lt;/a&gt;.  Others allow open carry when loaded.  Some require a permit.  Some don't.  Some only require a permit for handguns but not long guns.  If you're going to open carry (perhaps a hunting rifle on a sling), make sure that the local area allows this.&lt;/p&gt;&#xA;&lt;h3&gt;Concealed carry&lt;/h3&gt;&#xA;&lt;p&gt;Some locations prohibit concealed carry outright (to the best of my knowledge, you still can't carry concealed in Chicago, for example).  Other states allow concealed carry with a permit from either that state or &lt;a href=&quot;http://www.usacarry.com/concealed_carry_permit_reciprocity_maps.html&quot; rel=&quot;noreferrer&quot;&gt;a state which they have reciprocity with&lt;/a&gt;.  So, for example, a Mississippi permit would be honored in Texas, but not in Nebraska.  Others allow concealed carry without a permit at all (that is, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Second_Amendment_to_the_United_States_Constitution&quot; rel=&quot;noreferrer&quot;&gt;2nd Amendment&lt;/a&gt; is your permit).  First, be sure that your concealed permit has reciprocity with the destination state.&lt;/p&gt;&#xA;&lt;p&gt;Even if you think you're open carrying, watch out.  &lt;strong&gt;In some states, the act of being in a vehicle, no matter how visibly your firearm is displayed, makes it concealed carry.&lt;/strong&gt;  If you don't have a concealed carry permit, you may be in violation.&lt;/p&gt;&#xA;&lt;h1&gt;Is there anything else waiting out there to bite me?&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;&lt;a href=&quot;http://www.nraila.org/gun-laws/articles/2010/guide-to-the-interstate-transportation.aspx&quot; rel=&quot;noreferrer&quot;&gt;Oh yes.&lt;/a&gt;&lt;/h3&gt;&#xA;&lt;p&gt;For example, Rhode Island.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A Rhode Island carry permit is generally required to&#xA;transport a handgun in a vehicle. This requirement does not apply,&#xA;however, to the holder of an out-of-state carry permit who intends to&#xA;travel uninterrupted through the state.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Is a fuel stop an &amp;quot;interruption&amp;quot;?&lt;/p&gt;&#xA;&lt;p&gt;Or New Jersey.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[New Jersey] State law generally prohibits any person from knowingly possessing or&#xA;transporting any rifle or shotgun without first having obtained a New&#xA;Jersey firearms purchaser identification card (FPIC),or from&#xA;possessing or transporting any handgun without first having obtained a&#xA;New Jersey handgun carry permit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Or Chicago.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Chicago, for example, bans handguns declared “unsafe” by the&#xA;Superintendent of the Department of Police, so-called “assault&#xA;weapons,” machine guns and other firearms regulated under the National&#xA;Firearms Act, “laser sight accessories,” firearm silencers or&#xA;“mufflers,” “high-capacity” (i.e., more than 12-round) magazines, and&#xA;“metal piercing bullets” (which include ammunition with non-lead&#xA;projectiles).  All these items are subject to seizure and forfeiture.&#xA;In some cases, the local ordinances have no explicit exceptions to&#xA;these bans for travelers merely passing through the jurisdiction&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Or New York City.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Possession of a handgun within New York City requires a New York City&#xA;handgun license or a special permit from the city police commissioner&#xA;validating a state license within the city. Even New York state&#xA;licenses are generally not valid within New York City unless a&#xA;specific exemption applies, such as when the New York City police&#xA;commissioner has issued a special permit to the licensee or “the&#xA;firearms covered by such license are being transported by the licensee&#xA;in a locked container and the trip through the city of New York is&#xA;continuous and uninterrupted.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Look, just tell me what to do.&lt;/h1&gt;&#xA;&lt;p&gt;Fine.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Carry your firearms unloaded, locked, and inaccessible.&lt;/li&gt;&#xA;&lt;li&gt;Make as few intermediate stops as possible&lt;/li&gt;&#xA;&lt;li&gt;Know and comply with all local laws both at your departure and your destination&lt;/li&gt;&#xA;&lt;li&gt;Stay out of sterile areas while armed on airport property&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-03T04:58:00.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1501" PostTypeId="1" AcceptedAnswerId="1523" CreationDate="2014-02-02T22:54:38.943" Score="1" ViewCount="1515" Body="&lt;p&gt;I am looking for an Aerospace Engineering program in the EU. I heard the &lt;a href=&quot;http://www.tudelft.nl/en/study/master-of-science/master-programmes/aerospace-engineering/&quot; rel=&quot;nofollow&quot;&gt;Aerospace Engineering Department&lt;/a&gt; in Delft University in the Netherlands is one of the best programmes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I prefer English speaking countries, such as the Netherlands, Scotland, and Scandinavian countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be more specific I would like to study about the operation of airlines, airports, maintenance, how to do aircraft take-off performance calculations, and regulations relating to the operation of EFB applications.&lt;/p&gt;&#xA;" OwnerUserId="479" LastEditorUserId="479" LastEditDate="2014-02-03T12:07:17.213" LastActivityDate="2016-02-12T19:57:25.573" Title="Aerospace Engineer program in EU?" Tags="&lt;career&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2014-02-14T01:53:25.850" ContentLicense="CC BY-SA 3.0" />
  <row Id="1502" PostTypeId="1" AcceptedAnswerId="1504" CreationDate="2014-02-03T01:56:00.653" Score="13" ViewCount="26502" Body="&lt;p&gt;I was recently having a conversation where the term &quot;clearance delivery&quot; popped up, and was talking about his time flying into PHX, but in all of my time flying, I've never heard of the term before! Could someone explain to me what exactly is this for, and where would you find this?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="69" LastEditDate="2014-02-03T02:26:47.017" LastActivityDate="2014-02-03T02:26:47.017" Title="What is &quot;clearance delivery&quot; meant for?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1503" PostTypeId="2" ParentId="1499" CreationDate="2014-02-03T02:01:21.303" Score="1" Body="&lt;p&gt;NOAA has a great guide on their website called &lt;a href=&quot;http://www.srh.noaa.gov/epz/?n=pilots_guide&quot; rel=&quot;nofollow&quot;&gt;A Pilot's Guide to Aviation Weather Services&lt;/a&gt; which covers these (and more)!  They actually describe it better than I could.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short version though is that TIBS is a telephone weather service while TWEB is a recorded route briefing that you can listen to while airborne.  Both are used for supplemental information and don't replace an official briefing.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;TIBS&lt;/strong&gt; Telephone Information Briefing Service  &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;TWEB&lt;/strong&gt; Transcribed Weather Enroute Broadcast  &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;PATWAS&lt;/strong&gt; Pilot's Automatic Telephone Weather Answering Service&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TRANSCRIBED WEATHER BROADCASTs (TWEB) are continuous broadcasts of&#xA;  recorded NOTAM and weather information prepared for a 50-nautical mile&#xA;  wide zone along a route and for selected terminal areas. TWEBs are&#xA;  broadcast over selected NDB and VOR facilities and generally contain a&#xA;  weather synopsis, in-flight advisories, route and/or local vicinity&#xA;  forecasts. Winds Aloft Forecasts, current weather reports, NOTAMs, and&#xA;  special notices. TWEB outlets are listed below by state:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PILOT'S AUTOMATIC TELEPHONE WEATHER ANSWERING SERVICE (PATWAS), and&#xA;  the TELEPHONE INFORMATION BRIEFING SERVICE (TIBS), provide continuous&#xA;  recordings of weather and aeronautical information. The information&#xA;  may include area and/or route briefings, airspace procedures, and&#xA;  special announcements. Telephone numbers for PATWAS and TIBS locations&#xA;  are found in the Airport/Facility Directory.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TWEBs, PATWAS, and TIBS are for preflight or inflight planning and&#xA;  should not be considered a substitute for formal preflight briefings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-03T02:01:21.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1504" PostTypeId="2" ParentId="1502" CreationDate="2014-02-03T02:17:18.427" Score="15" Body="&lt;p&gt;&quot;Clearance Delivery&quot; is exactly what you've surmised it is - a frequency used on the ground to copy your initial clearance from ATC before you take off.&lt;br&gt;&#xA;The idea behind using a dedicated frequency for this is that it avoids tying up the ground control frequency (used for authorizing ground movement on taxiways and such) with long clearances and readbacks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearance Delivery is found at controlled fields. Pilots operating under Instrument Flight Rules will generally use it prior to each flight, and at airfields in class C or class B airspace it's used by VFR pilots as well (since they'll be talking to departure controllers very shortly after take off until clear of the controlled airspace).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At less busy fields Clearance Delivery is often staffed by the same controller working Ground (e.g. at &lt;a href=&quot;http://www.airnav.com/airport/KISP&quot;&gt;Long Island / Mac Arthur&lt;/a&gt; it's usually the same controller working both positions), and at some airports clearances will be read over the ground control frequency when it's not busy. At busier airports clearance is usually its own position - possibly with multiple frequencies (e.g. at &lt;a href=&quot;http://www.airnav.com/airport/lga&quot;&gt;La Guardia&lt;/a&gt; there is a separate clearance frequency for helicopters).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-03T02:17:18.427" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1505" PostTypeId="2" ParentId="1449" CreationDate="2014-02-03T04:56:59.940" Score="5" Body="&lt;p&gt;Not all flaps are the same and you should read the poh for the suggested and prescribed way to operate the aircraft you are flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the Grumman AA5 series flaps provide a lot of drag and no real extra lift nor slow speed ability.  They do allow sharp descents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas a Cessna 172 flaps will increase lift and lower stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read the manuals.&lt;/p&gt;&#xA;" OwnerUserId="793" LastActivityDate="2014-02-03T04:56:59.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1507" PostTypeId="1" AcceptedAnswerId="1509" CreationDate="2014-02-03T11:31:58.767" Score="17" ViewCount="2999" Body="&lt;p&gt;How does it feel when you change from an aircraft to another but of the same model?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes when you change a car and drive another one of exactly the same model you do feel differences due to various factors like wear and tear, mileage, different service schedules etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this apply also to aircraft or are they exactly the same?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="97" LastEditDate="2014-02-03T23:47:51.920" LastActivityDate="2015-03-11T08:41:29.690" Title="Do two of the same model of aircraft feel different to fly?" Tags="&lt;aircraft-design&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1508" PostTypeId="2" ParentId="1501" CreationDate="2014-02-03T12:35:13.557" Score="4" Body="&lt;p&gt;The topics you describe are certainly part of aerospace engineering, however they are somewhat specialized topics. I am not trying to discourage you, but Aerospace engineering involves a lot of mathematics and physics. If these fields do not appeal to you, you will be having a hard time to get through to the sweeter parts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some universities only offer a Master programme for Aerospace engineering, which typically follows on to their Bachelor programme Mechanical engineering. If you are really interested in aviation, I would recommend to select a full (Bachelor and Master) Aerospace programme. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerospace engineering programmes generally involve a thorough basis of mathematics (linear algebra, calculus) , physics (mechanics, thermodynamics), material sciences before introducing more specialized subjects like aerodynamics, aircraft performance, and space flight. At bachelor level, you will get an introduction to a diverse set of aerospace related subjects. At master level you will go deeper into an area, although you will have to accept that you won't master all subjects you mention. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had a good time at Delft University, it certainly has a good Aerospace Engineering programme which I would recommend. &#xA;In addition I had the pleasure to work with a graduate from Bristol university, she is very knowledgeable. I'd certainly look into their programme as well. &#xA;For Scandinavia I would look into aerospace programmes in Sweden. Sweden has quite an active Aerospace industry. Linköping is their centre of Aerospace Engineering.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-02-03T12:35:13.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1509" PostTypeId="2" ParentId="1507" CreationDate="2014-02-03T13:09:03.973" Score="19" Body="&lt;p&gt;This applies to aircraft just as well as it does to cars. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are little differences between aircraft from the moment they come of the production line, however these are barely observable. Over time the differences become larger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, jet engine performance slowly deteriorates until the next overhaul, leading to increased fuel consumption. Another source of differences is permanent deformation of the aircraft due to extreme loads. A well known example of this is the B747 of &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot;&gt;China Airlines flight 006&lt;/a&gt; that had a permanently bent wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airlines flight crew sometimes know that specific airframes have specific characteristics like difficult lateral trim. The flight operations department will observe differences in fuel consumption between airframes of the same model. That can be a reason not to deploy a specific aircraft on long routes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the wear and tear like causes there are design difference as well between airframes of the same model. This is described well by Terry. &#xA;A captain once told me she almost aborted an approach in IMC when the radar altimeter did not come up on final. It turned out the RAD ALT display was at a different position on the screen in this particular aircraft. Their fleet had several second hand aircraft with slight cockpit differences which caused confusion all the time. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-04T00:41:07.260" LastActivityDate="2014-02-04T00:41:07.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1510" PostTypeId="1" AcceptedAnswerId="1512" CreationDate="2014-02-03T13:37:20.863" Score="12" ViewCount="19487" Body="&lt;p&gt;I am an aviation fan, relatively new to the industry.  While I thoroughly enjoy plane spotting at my local KORD airport, at times I tune to LiveATC and Flightaware to get my fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, my observations are that flightaware is a bit delayed 3-5 minutes, and not all air traffic is shown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried Flightradar24, it is more current, but wildly inaccurate at times and a bit &quot;synthetic&quot; as they try to fill in the data gaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from getting into an actual ATC tower, which I am sure is nearly impossible for a civilian, what are my best options as far as getting my fix in?  Apps, services, etc (paid and free), doesn't matter.&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="572" LastEditDate="2015-02-19T10:03:00.623" LastActivityDate="2015-02-19T10:03:00.623" Title="Where can I find real-time flight tracking with the least amount of delay?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;&lt;online-tracking&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1512" PostTypeId="2" ParentId="1510" CreationDate="2014-02-03T14:04:50.247" Score="11" Body="&lt;p&gt;You can buy a DVB-TV USB stick for around €20, which will allow you to receive ADS-B data:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gaonxt.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Up from that, you can get a high-end ADS-B receiver that costs about €750:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eQqGlt.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, FlightRadar24 offers free hardware in selected locations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ufj4nt.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bear in mind that these devices will only allow you to receive signals within a relatively small area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing worth noting is by contributing the data received by these devices, you get a free FlightRadar24 Premium subscription.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lots more information is available at &lt;a href=&quot;http://www.flightradar24.com/increase-coverage&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightRadar24 &gt; Increase Coverage&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-19T22:02:05.893" LastActivityDate="2014-04-19T22:02:05.893" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1513" PostTypeId="2" ParentId="1510" CreationDate="2014-02-03T14:06:48.477" Score="3" Body="&lt;p&gt;If you don't mind dropping some cash, &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B00A1VSO9M&quot; rel=&quot;nofollow&quot;&gt;a handheld radio scanner&lt;/a&gt; will let you listen to as-it-happens ATC transmissions.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combine that with a current copy of the &lt;a href=&quot;http://www.airnav.com/airport/KORD&quot; rel=&quot;nofollow&quot;&gt;Chicago O'Hare approach procedures&lt;/a&gt; (near the bottom of the page) and you'll be able to follow traffic in real time by looking out your window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you're not tied to O'Hare or you just feel like getting out for a day, head over to Midway.  There's a Giordano's right off the approach end of the airport.  You can get you some pizza while looking out the window and watching Southwest Airlines squeeze 737s onto a 6,500 foot runway.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-02-03T14:06:48.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1514" PostTypeId="5" CreationDate="2014-02-03T15:05:21.827" Score="0" Body="&lt;p&gt;A Private Pilot's License (PPL) allows an individual to act as 'pilot in command' of an aircraft for private purposes, i.e. not for pay (more precisely, not for compensation). A PPL holder may carry passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A PPL is often the first pilot's license that someone earns and it is usually a pre-requisite for more advanced licenses such as commercial or ATP licenses. The requirements for a PPL as well as the specific privileges it allows are different in different countries, e.g. a US PPL allows pilots to fly at night but a European PPL does not. PPLs are typically issued for a specific category or class of aircraft, e.g. someone may hold a helicopter PPL but not a fixed-wing PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some countries there may be other types of private license that are similar to a PPL but have different restrictions and privileges. For example, the US issues recreational and sport pilot certificates that are more restricted than a 'full' PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &quot;license&quot; is not always the correct term: in the US, the FAA issues certificates, not licenses, although informally many people refer to licenses anyway, probably because of an implicit comparison to a driver's license.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Private_pilot_licence&quot; rel=&quot;nofollow&quot;&gt;Private pilot license&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/&quot; rel=&quot;nofollow&quot;&gt;Airmen certification&lt;/a&gt; (FAA)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-09-11T15:00:32.867" LastActivityDate="2014-09-11T15:00:32.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1515" PostTypeId="4" CreationDate="2014-02-03T15:05:21.827" Score="0" Body="A Private Pilot's License (PPL) allows individuals to fly aircraft for pleasure or personal travel, but not for pay. It is often the first pilot's license that someone earns and is usually required for more advanced licenses." OwnerUserId="774" LastEditorUserId="62" LastEditDate="2014-09-11T15:00:13.780" LastActivityDate="2014-09-11T15:00:13.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1516" PostTypeId="5" CreationDate="2014-02-03T15:09:36.357" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-02-03T15:09:36.357" LastActivityDate="2014-02-03T15:09:36.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1517" PostTypeId="4" CreationDate="2014-02-03T15:09:36.357" Score="0" Body="Refers to questions asking about airline practices, procedures, and processes both in the employment arena and in flight." OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-02-03T16:06:35.310" LastActivityDate="2014-02-03T16:06:35.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1518" PostTypeId="2" ParentId="1507" CreationDate="2014-02-03T15:19:07.420" Score="4" Body="&lt;p&gt;Engine performance and control rigging are probably two of the more obvious ways this is noticeable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft with cable or pushrod controls, the system can develop slack and create a null zone where moving the controls does nothing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as engines go, every engine wears differently. Some get crappy field overhauls and never really produce their original power again. Others are nearing end of life and have low compression in one or more cylinders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless you're flying aircraft from an exceptionally well maintained fleet that distributes the flight hours fairly evenly, moving between models will almost always highlight a difference or two.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-02-03T15:19:07.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1519" PostTypeId="2" ParentId="1510" CreationDate="2014-02-03T15:25:25.450" Score="1" Body="&lt;p&gt;All data from the FAA is delayed by at least five minutes unless you can show an actual need for real-time data.  Additional information is provided in their agreement for accessing the data (below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have pointed out, there is various hardware that can be used to see real-time data in a small local area, but it only shows aircraft that are properly equipped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as going into a control tower, take a look at &lt;a href=&quot;https://aviation.stackexchange.com/q/615/69&quot;&gt;What is the security policy for getting into a Control Tower?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.fly.faa.gov/ASDI/asdidocs/ASDI_MOA_Ver_1.4a.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA ASDI Memorandum of Agreement&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As a result of the aviation-related attacks of September 11, 2001 in&#xA;  the United States, the FAA reviewed security risks related to the&#xA;  ASDI/NASSI feed and determined that only Subscribers that are Class&#xA;  One Users are authorized to receive the full near real time ASDI and&#xA;  NASSI data set (this includes Direct Subscribers with Class One&#xA;  Indirect Subscribers).  Subscribers that are Class Two Users are not&#xA;  authorized to receive near real time flight tracking and position&#xA;  messages.  Class Two Users are only authorized to receive the full&#xA;  ASDI and NASSI data set that has been time-delayed at least 5 minutes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Class 1:&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A Class One User is a professional aviation organization with an&#xA;  established flight dispatch or planning function that requires near&#xA;  real time positional flight-tracking capabilities.  This organization&#xA;  must have direct responsibility for dispatching or tracking aircraft&#xA;  it owns or be contracted by the owner of the aircraft to do so.&lt;br&gt;&#xA;  Examples are airlines, regional air carriers, air taxis, any&#xA;  organization providing dispatch or tracking functions for aircraft&#xA;  owners, flight operation centers, government users (as described in&#xA;  Section &#xA;  5.5), and professional flight planning service providers.   Fixed Base Operators (FBOs), corporate flight departments, and part 135 operators&#xA;  must have direct responsibility for dispatching or tracking aircraft&#xA;  to qualify as a Class One User.  The FAA shall be the  final arbiter&#xA;  for any disputes regarding the interpretation of this Section.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Class 2:&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A Class Two User is any user not meeting the criteria of a Class One User (e.g., most general aviation; non-aviation-related&#xA;  entities and individuals; any other entity without a specific&#xA;  requirement for near real time positional flight-tracking).  Class Two&#xA;  Users can obtain Class Two (time-delayed data) either directly from&#xA;  the FAA Traffic Flow Management System Hubsite Class Two ASDI/NASSI&#xA;  interface or from Direct Subscribers that provide time-delayed Class&#xA;  Two data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-02-03T15:25:25.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1520" PostTypeId="2" ParentId="1507" CreationDate="2014-02-03T15:37:24.410" Score="13" Body="&lt;p&gt;The biggest differences that you will notice is that, especially on older models, the panel in the cockpit is not standardized and the avionics can vary wildly in both location and operation.  As an example, take a look at these two 172 panels:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://iho.hu/img/repules_12_03/120305_Glass/172panel.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WaBFEm.jpg&quot; alt=&quot;C172-1&quot;&gt;&lt;/a&gt; &lt;a href=&quot;http://1823.img.pp.sohu.com.cn/images/blog/2011/3/19/11/11/u40837436_12f85648389g214.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nQhnOm.jpg&quot; alt=&quot;C172-2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lighting is another thing that can vary from just barely passable to sleek modern solutions that allow you to see everything easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should definetely take some time with any new airplane on the ground and learn where everything is before you take it up for an actual flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from these differences, as others have pointed out, you may notice some small performance differences depending on the total time on the engine, etc.  These usually aren't that big of a difference as long as they are properly maintained.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="65" LastEditDate="2015-03-10T16:59:54.477" LastActivityDate="2015-03-10T16:59:54.477" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1521" PostTypeId="2" ParentId="1507" CreationDate="2014-02-03T17:07:40.917" Score="22" Body="&lt;p&gt;In larger aircraft being flown by airlines that buy their airplanes from the carriers that originally bought them from the manufacturers, this can be a real problem. For example, Boeing used to allow considerable customization of 747 cockpits. For example, the forward cockpit overhead panel of 747-100 and -200 aircraft made for TWA had the switches reversed from all other purchasing airlines. The panel was at an angle, neither vertical nor horizontal. TWA treated it as a logically horizontal panel in that if you wanted a switch on, you moved it forward. All other airlines treated it as a logically vertical panel in that if you wanted a switch on, you moved it up. Thus, from the pilot's point of view, to turn on a switch on a TWA airplane, you moved the switch in the reverse direction of the other airplanes. Things got especially bad when switches from, say, an ex-Pan Am airplane were put in an ex-TWA airplane. Towards the end of my career (retired 1999), if I was in an ex-TWA airplane, I always looked directly at an overhead panel switch before throwing it. The differences section of the QRH (Quick Reference Handbook) of both 747 carriers I flew for was lengthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I remember, the FAA finally stepped in and required Boeing to offer less cockpit customization.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-03T17:07:40.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1522" PostTypeId="2" ParentId="1507" CreationDate="2014-02-03T18:15:39.097" Score="9" Body="&lt;p&gt;A lot of this depends on what you mean by &quot;the same model&quot; - there is a lot more variation between aircraft than there is between cars, and a lot more that the pilot can customize. While every Ford Mustang you get in will be relatively similar even if you're going from mid-1960s to early 2000s models you could get in two planes that came off the assembly line right after each other yet seem completely different depending on what their owners have done to the avionics and airframe over the years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of the avionics and &lt;a href=&quot;https://aviation.stackexchange.com/a/1520/64&quot;&gt;panel layout&lt;/a&gt; and possible &lt;a href=&quot;https://aviation.stackexchange.com/a/1518/64&quot;&gt;engine performance&lt;/a&gt; variation every aircraft is different: for the most part they're hand-assembled (even airliners to some extent) so there's variation there, and planes last a long time so each one has aged differently.&lt;br&gt;&#xA;One airframe may have been in accidents and had major repairs that weren't quite to spec, another may have rigging issues (I flew a trainer that required left rudder in a right turn to remain coordinated), so you have to develop a feel for each plane you fly.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As another example of variation between planes consider that both Cessna and Piper have produced very long-lived &quot;models&quot;: Cessna's 172 and Piper's Cherokee family (which I've picked because both are still in production today).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By one measure these are the same &quot;model&quot; (It's a Cessna 172, or a Piper PA28), and they'll fly largely the same as any other plane of the same type.&lt;br&gt;&#xA;By another measure there are many different models in each family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example you could have a  Cessna 172 E with mechanical flaps, or a Cessna 172 F with electric flaps. You could have a Cherokee C model with &quot;barn door&quot; air vents and overhead trim, or an E model with the vents in the wing root and a trim wheel between the seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes these differences won't matter much to the pilot - the difference in air vent location in the Cherokees doesn't really affect your flying.  Other times it's a difference you need to be aware of, like whether your flap controls are a switch on the panel or a lever on the floor in the Cessna, or whether you reach up or down for trim in the Cherokee.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-02-03T18:15:39.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1523" PostTypeId="2" ParentId="1501" CreationDate="2014-02-03T20:11:46.327" Score="3" Body="&lt;p&gt;&lt;em&gt;&lt;sub&gt;Updated: February 2016&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind this is &lt;strong&gt;aerospace engineering&lt;/strong&gt;, but some places offer stuff like &lt;strong&gt;aviation management&lt;/strong&gt;, which might be more what you are after, depending on what you want to do. TU Delft is more tailored to the former.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While most of the topics of interest you mention will only appear in some capacity in the TU Delft AE BSc, they will appear in more detail and focus in certain MSc tracks. I'm not sure which you are after. &#xA;While you mentioned Sweden, they do the first year BSc in Swedish, which stops you unless you know the language (All MSc is English). KTH (Kungliga Tekniska Högskolan), Stockholm is normally considered the best TU in Sweden and does AE as MSc. Again, it might not match what you're looking for. Scotland has plenty of programs- a search in the UCAS serach engine should suffice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wherever you go, it's a big cultural question as well. What are your expectations of for instance social life? There are two similar but still different countries &amp;amp; cultures. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I am a former BSc Aerospace Engineering student at TU Delft. In my opinion, the uni has great facilities and it's for most part a very good (of course with the occasional bad lemons that you would find anywhere). Student teams are also of very high quality. The topics you mention thought would probably be more dealt with in the master program however. The BSc. is pretty 'heavy' engineering (calculations/exercises) for most part with a lot of conceptual and a little practical work to try and brighten up your day :) TU Delft may be good but you won't get through it on a banana peel. First year dropout rate is ~55% according to one &lt;a href=&quot;http://delta.tudelft.nl/artikel/bsa-vertoont-dalende-lijn/30344&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;. University &lt;a href=&quot;http://www.tudelft.nl/en/study/undergraduates-bachelors/undergraduate-programmes/aerospace-engineering/study-in-numbers/&quot; rel=&quot;nofollow&quot;&gt;officially&lt;/a&gt; says 76% however. A minority pull it off in the official three years but most take longer. Important consideration if you’re paying the non-EU fee.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2016-02-12T19:57:25.573" LastActivityDate="2016-02-12T19:57:25.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1524" PostTypeId="1" AcceptedAnswerId="1525" CreationDate="2014-02-03T20:19:25.173" Score="18" ViewCount="2992" Body="&lt;p&gt;I was told that certain plane spotting activities like taking photos of aircraft taking off and landing could be illegal in the US since 9/11? What are the regulations on this, and what should I be aware of before I set my camera up at the end of the runway?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="946" LastEditDate="2019-02-14T17:13:13.073" LastActivityDate="2019-02-14T17:13:13.073" Title="What are the regulations regarding plane spotting in the US?" Tags="&lt;usa&gt;&lt;regulations&gt;&lt;plane-spotting&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1525" PostTypeId="2" ParentId="1524" CreationDate="2014-02-03T20:50:56.160" Score="18" Body="&lt;p&gt;Generally absent a specific prohibition you can take a photo of anything you can see with your eyes from public property (like a sidewalk). That includes airports, airplanes, bridges, tunnels, police officers, kittens, and unicorns.&lt;br&gt;&#xA;(For more in-depth information check out &lt;a href=&quot;http://www.andrewkantor.com/legalrights/Legal%20Rights%20of%20Photographers2.pdf&quot; rel=&quot;noreferrer&quot;&gt;Andrew Kantor's excellent article&lt;/a&gt; and &lt;a href=&quot;http://www.krages.com/phoright.htm&quot; rel=&quot;noreferrer&quot;&gt;Bert Krages' excellent one-page flyer on photographers' rights&lt;/a&gt;, or check out &lt;a href=&quot;http://photography.stackexchange.com&quot;&gt;http://photography.stackexchange.com&lt;/a&gt; - they've &lt;a href=&quot;https://photo.stackexchange.com/q/15873/2147&quot;&gt;covered airport photography&lt;/a&gt;, though not in any real depth, and I'm sure they have some street photographers well versed in the legal aspects of taking pictures.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So what constitutes a &quot;specific prohibition&quot; on photography? Generally a clearly visible sign that says &lt;code&gt;PHOTOGRAPHY PROHIBITED&lt;/code&gt; (the old Grumman facility in Bethpage had such signs on all of the fences where there was a decent view of the runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Absent such a clear prohibition you're free to take all the photos you want as long as you're on public property while you're doing it (i.e. &quot;not trespassing on airport property&quot;), but be aware that some law enforcement officials may not see it that way, and you may have to have some uncomfortable interactions with them.&lt;br&gt;&#xA;In my experience most &lt;em&gt;police officers&lt;/em&gt; are well versed in the law, though occasionally you'll find one who isn't. You're more likely to have trouble with a &quot;rent-a-cop&quot; security guard though.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you want really good photographs (and you're not photographing at a major airport like JFK or O'Hare) you might want to speak to the airport management. At smaller airports someone - either airport personnel or a local pilot - might be able and willing to escort you airside where you can get some really great shots.&lt;br&gt;&#xA;It helps in this situation if you have a body of work you can show (either published photos or art prints). The caveat is that many airports will also ask that you carry some kind of insurance while you're photographing on their property (and at larger airline fields that requirement can be substantial).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:44:06.937" LastActivityDate="2014-02-03T20:50:56.160" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="1526" PostTypeId="2" ParentId="1524" CreationDate="2014-02-03T20:59:14.867" Score="9" Body="&lt;p&gt;The &lt;a href=&quot;https://www.aclu.org/free-speech/know-your-rights-photographers&quot;&gt;ACLU notes&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Transportation Security Administration (TSA) acknowledges that photography is permitted in and around airline security checkpoints as long as you're not interfering with the screening process. The TSA does ask that its security monitors not be photographed, though it is not clear whether they have any legal basis for such a restriction when the monitors are plainly viewable by the traveling public.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The TSA also warns that local or airport regulations may impose restrictions that the TSA does not. It is difficult to determine if any localities or airport authorities actually have such rules. If you are told you cannot take photographs in an airport you should ask what the legal authority for that rule is.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Popular among photographers, &lt;em&gt;&lt;a href=&quot;http://www.krages.com/ThePhotographersRight.pdf&quot;&gt;The Photographer's Right&lt;/a&gt;&lt;/em&gt;, a summary of legal rights related to photography (prepared by a lawyer), says that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are some exceptions to the general rule. A significant one is that commanders of military installations can prohibit photographs of specific areas when they deem it necessary to protect national security.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Despite misconceptions to the contrary, the following subjects can almost always be photographed lawfully from public places:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;accident and fire scenes, children, celebrities, bridges and other infrastructure, residential and commercial buildings, industrial facilities and public utilities, &lt;strong&gt;transportation facilities (e.g., airports)&lt;/strong&gt;, criminal activities, law enforcement officers&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some airports are more spotter-friendly than others. You can search online to find discussion forums on people's opinions which ones are better than others. Any airport that is private property (not many major ones, I believe) of course can do whatever they want, but many airports stop photography for a &quot;safety&quot; measure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Standard IANAL disclosure.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-02-03T20:59:14.867" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1527" PostTypeId="1" AcceptedAnswerId="1528" CreationDate="2014-02-03T21:26:23.677" Score="11" ViewCount="8045" Body="&lt;p&gt;I'm thinking of building some of physical aspects of a flight simulator, such as the overhead panels and pedestal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a &lt;strong&gt;publication available where I could find detailed dimensions of cockpit panel sizes&lt;/strong&gt; of say Boeing 737 and A320s? I've found some pictures online but they don't quite have the detail I would like. Google images shows a few results with detailed dimensions, so I'm wondering where they got theirs from... actual measurements perhaps? (there are photos of measurements, but i'd like something maybe a little more exact)  Is there maybe a standard size of these panels, also on the larger jets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/4/43/Overhead_panel_of_an_Airbus_A320_during_cruise.jpg&quot; alt=&quot;A320 Overhead&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sort of thing I'm looking for: &#xA;&lt;img src=&quot;https://i.stack.imgur.com/Sd7QK.jpg&quot; alt=&quot;AP Dimensions&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2018-12-29T00:51:57.313" LastActivityDate="2018-12-29T00:51:57.313" Title="Where can I find detailed dimensions of aircraft panels?" Tags="&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1528" PostTypeId="2" ParentId="1527" CreationDate="2014-02-03T21:50:50.250" Score="7" Body="&lt;p&gt;There appears to be some (free) quality materials accessible through the download section of &lt;a href=&quot;http://www.opencockpits.com/index.php/en/download/&quot; rel=&quot;nofollow&quot;&gt;Open Cockpit's Website&lt;/a&gt;, including CAD (.dwg) files and drawings such as this &lt;a href=&quot;http://www.opencockpits.com/index.php/en/download/item/b737-overhead?category_id=48%20%22737%20Overhead&quot; rel=&quot;nofollow&quot;&gt;737 Overhead Panel&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(seem to have at least partially answered my own question, but a clear technical drawing if somebody could provide/suggest a source of one would be greatly appreciated)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-04T15:49:41.353" LastActivityDate="2014-02-04T15:49:41.353" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1529" PostTypeId="1" AcceptedAnswerId="1530" CreationDate="2014-02-03T22:29:17.973" Score="17" ViewCount="7133" Body="&lt;p&gt;I understand that a SAAAR / RNP AR is a &quot;special&quot; approach and that special approval is required to even get the approach plate, but what exactly is it?  Aspen is an example of an airport that has one.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14897" LastEditDate="2021-03-12T19:07:03.493" LastActivityDate="2021-03-12T19:07:03.493" Title="What is a SAAAR / RNP AR instrument approach?" Tags="&lt;faa&gt;&lt;approach&gt;&lt;iaps&gt;&lt;faa-approval&gt;&lt;rnp&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1530" PostTypeId="2" ParentId="1529" CreationDate="2014-02-04T00:29:49.850" Score="20" Body="&lt;p&gt;First allow me to give a quick introduction to RNAV and RNP before geting to SAAAR / RNP AR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Area Navigation (RNAV) is a method of instrument flight rules (IFR) navigation that allows an aircraft to fly on any desired path within the coverage of referenced navigation beacons, rather than navigating directly to and from the beacons. In other words, waypoints can be defined at arbitrary locations and paths betweens those points (and traditional navigation beacons as well) can be defined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;RNAV routes are coded into the navigation database by ARINC 424 path-terminators. Whilst RNAV routes can be designed in such a way that the lateral path is strictly described, in general the lateral path has a quite some freedom due to floating leg types (e.g. turn at altitude, fly heading etc) and wiggle room for the aircraft to negotiate the turns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the route is described only by TF (track to fix) and RF (radius to fix) path terminators, the lateral path is fully fixed. These fixed lateral paths allow procedure designers, for example, to design approaches through mountain valleys down to the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;RNAV defines a 95% accuracy bounds. For example, RNAV 1 requires the aircraft to be within 1 NM from the path centreline 95% of the time. The route designer will ensure a 2 NM obstacle free zone around the path in such a case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that RNAV provides no assurance against exceeding the 2 NM zone. There is no automated system monitoring required. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Potentially causes of deviations between the path intended by the procedure designer and the actual flown path can be grouped into three categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First, there is the Path Definition Error. This is caused by database&#xA;coding mismatch with the original path design.&lt;/li&gt;&#xA;&lt;li&gt;Second, there is the Path Steering Error, caused by the combination&#xA;of display inaccuracies on the Navigation Display and the inability&#xA;of the pilot or the autoflight system to stay exactly on path (Flight&#xA;Technical Error).&lt;/li&gt;&#xA;&lt;li&gt;Third, there is Position Estimation Error, which is the difference between the position of the aircraft estimated by the navigation system and the true position.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is not unthinkable that while normally (95% of the time) the aircraft will fly within e.g. 1 NM of the intended centre line, there are cases that the aircraft will exceed the 1NM by far, possibly even busting the 2 NM obstacle free zone. That could potentially ruin your day if it happens in a mountain valley.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is where RNP comes in. RNP (Required Navigation Performance) is basically RNAV with added protection. For example, RNP 1 again defines a 1NM accuracy for 95% of the time, but it also offers 99.999% assurance that it will not exceed the 2NM. It will raise an alert if the 2 NM value will potentially be exceeded. So in addition to what RNAV offers, it includes a system monitoring function that will detect navigation errors and alerts for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RNP value alway gives the 95% accuracy, the 99.999% assurance (integrity) limit is always at twice that value. So RNP 0.3 means that the aircraft has to stay within 0.3 NM of the designed path centreline 95% of the time. And if it exceeds the 0.6 NM threshold, an alert will be raised with 99.999% certainty. &#xA;RNP systems therefore require a system monitoring function.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To ensure that the RNP values are met, each of the three error sources mentioned earlier must be under control. For RNP values down to 1 NM that is not much of a challenge. Standard procedures and equipment are deemed to be sufficient here. (of course the required RNP values must be met by the Actual Navigation Performance) &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If an approach requires tighter limits, such as RNP 0.3 or 0.15, then special authorization is required.&lt;br&gt;&#xA;This is where &lt;strong&gt;SAAAR&lt;/strong&gt; comes in (&lt;b&gt;S&lt;/b&gt;pecial &lt;b&gt;A&lt;/b&gt;ircraft and &lt;b&gt;A&lt;/b&gt;ircrew &lt;b&gt;A&lt;/b&gt;uthorization &lt;b&gt;R&lt;/b&gt;equired), now renamed to RNP AR (RNP Authorization Required). RNP AR routes only make use of TF and RF leg types to fully fix the lateral path. RF legs are not supported by all navigation systems by default. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get authorization for RNP AR, the aircraft needs to comply with the applicable functional and performance requirements, the crew needs to be trained and lot's of documentation must be maintained. Basically proof must be provided that all of the three error terms are under strict control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a sense it is somewhat similar to ILS CAT III approval. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;References: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2090-101A.pdf%20%5BAC%2090-101A%5D&quot; rel=&quot;noreferrer&quot;&gt;AC 90-101A&lt;/a&gt; describes a means of compliance for RNP AR &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/tv/?mediaId=836&quot; rel=&quot;noreferrer&quot;&gt;RNAV / RNP presentation&lt;/a&gt; gives a good explanation of RNAV and RNP&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-03-13T12:55:50.427" LastActivityDate="2017-03-13T12:55:50.427" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1531" PostTypeId="1" AcceptedAnswerId="1532" CreationDate="2014-02-04T11:57:44.350" Score="25" ViewCount="43346" Body="&lt;p&gt;A few days ago, a Copa flight from Porto Alegre to Panama was delayed from noon until 12:30 AM. The company explained that the high temperature (about 40 degrees Celsius) would require a longer runway for takeoff since the air was thinner, and that resulted in non-operational conditions for the wings and engines with the available runway length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One source (in portuguese): &lt;a href=&quot;http://www.radioguaiba.com.br/Noticias/?Noticia=515816&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.radioguaiba.com.br/Noticias/?Noticia=515816&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true? Can a high temperature really prevent takeoff?&lt;/p&gt;&#xA;" OwnerUserId="616" LastEditorUserId="13197" LastEditDate="2018-12-23T21:36:48.393" LastActivityDate="2018-12-23T22:06:12.960" Title="Does temperature affect takeoff performance?" Tags="&lt;aircraft-design&gt;&lt;weather&gt;&lt;aircraft-performance&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1532" PostTypeId="2" ParentId="1531" CreationDate="2014-02-04T12:53:51.493" Score="30" Body="&lt;p&gt;Yes, temperature effects airplane performance &lt;em&gt;both&lt;/em&gt; the engine itself and the aerodynamics involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What Is Density Altitude?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Density altitude is pressure altitude corrected for nonstandard&#xA;  temperature. As temperature and altitude increase, air density&#xA;  decreases. In a sense, it's the altitude at which the airplane &quot;feels&quot;&#xA;  its flying.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How Will High Density Altitude Affect Flight?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On a hot and humid day, the aircraft will accelerate more slowly down&#xA;  the runway, will need to move faster to attain the same lift, and will&#xA;  climb more slowly. The less dense the air, the less lift, the more&#xA;  lackluster the climb, and the longer the distance needed for takeoff&#xA;  and landing. Fewer air molecules in a given volume of air also result&#xA;  in reduced propeller efficiency and therefore reduced net thrust. All&#xA;  of these factors can lead to an accident if the poor performance has&#xA;  not been anticipated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Weather/Density-Altitude&quot; rel=&quot;noreferrer&quot;&gt;Tips for Flying in High Density Altitude Areas&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way of looking at it is that higher temperatures make the airplane fly the way it would at a higher altitude where the air is less dense. An airplane cannot climb to infinity, it has what is called a service ceiling [and an absolute ceiling] that the aircraft can no longer climb any higher. This also because of a decrease in air density, but for a different reason. Raising the temperature of the air also decreases this air density. You can use an &lt;a href=&quot;http://wahiduddin.net/calc/calc_da.htm&quot; rel=&quot;noreferrer&quot;&gt;Air Density Calculator&lt;/a&gt; or a &lt;strong&gt;Density Altitude Chart&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iPYzc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;to determine how the aircraft will fly. It is especially important at airports with short runways or high actual altitudes [Denver, Colorado for example] where the aircraft already may need to be near maximum performance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the density altitude is 4,000ft than that means that airplane will fly like it was at 4,000ft at standard atmospheric temperature. Standard atmospheric temperature [at sea level] is 15 degrees Celsius or 59 degrees Fahrenheit. An airplane departing at a sea level airport, at 100F would feel like it is already flying at over 2600ft. An airplane departing at a 5,000ft airport would feel like it is already flying at over 8700ft. If clearing the trees at the end of the runway was already a concern at this particular airport it may not happen anymore.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="391" LastEditDate="2014-02-04T13:36:54.797" LastActivityDate="2014-02-04T13:36:54.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1533" PostTypeId="2" ParentId="1531" CreationDate="2014-02-04T12:55:26.067" Score="7" Body="&lt;p&gt;Absolutely: thinner air, whether caused by a higher altitude or a higher temperature, decreases aircraft performance in two ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It decreases the amount of air going into the engine, which means that less fuel can be introduced in order to maintain the correct fuel to air mixture. This produces less power output from the engine &lt;strong&gt;and&lt;/strong&gt; decreases the thrust generated by the fans in the turbofan engines.  This increases the amount of time (and therefore runway distance) that it takes to accelerate to flying speed. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At a particular airspeed, there is less actual air (fewer air particles) moving across the wings.  Since this is what produces lift, the airplane must be moving faster in order to create the same amount of lift.  This requires more time, and therefore more runway. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Climb performance is also reduced for the same reasons, and can also be a factor preventing an aircraft from taking off if there are obstacles that must be out-climbed (there is also a minimum amount of climb required after takeoff for certification, so performance charts don't even have information past a certain point).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a &quot;real world&quot; example, take a look at this chart from a jet that I fly, and notice that the hotter the temperature or the higher the takeoff altitude, the lower the weight that you are allowed to takeoff at:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fyj2u.jpg&quot; alt=&quot;Falcon 50 Max Takeoff Weight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 40 deg C, even at seal level, this airplane is limited by climb performance to a takeoff weight of about 13,700 kg. (instead of the &lt;em&gt;normal&lt;/em&gt; 17,600 kg.), and this doesn't even consider the amount of runway required!  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exact same principle applies to runway distance required, but there are additional variables which make the graph much more complicated to follow:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QvbEt.jpg&quot; alt=&quot;DA50 Balanced Field Length&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-04T22:47:44.170" LastActivityDate="2014-02-04T22:47:44.170" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1534" PostTypeId="2" ParentId="1531" CreationDate="2014-02-04T12:59:52.320" Score="10" Body="&lt;p&gt;Yes, it is quite correct that an airplane requires a longer runway on a hot day. The effect is the same as being at a high altitude. High up on a hot day, in the middle of a low pressure zone is the worst, as the effects are combined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it comes down to is air density, less dense air means less &quot;stuff&quot; for the wings to sail through, generating less lift, and thus requires higher airspeed before being able to lift off. On top of that, engines need oxygen to fuel the combustion, less dense air means less oxygen and therefore less power output from the engine. And just as the wings are less effective, so are the propeller or fan blades, converting less engine power to thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in essence, low density means you'll need more airspeed to climb away from the ground, and you have less power at your disposal for reaching that airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A well known video taped &lt;a href=&quot;http://www.youtube.com/watch?v=OVM3RRd1vf0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stinson crash in Idaho&lt;/a&gt; a while back is generally attributed to high density altitude. High density altitude means low air density (may sound counterintuitive, but it basically means that it is equivalent of a high altitude, where the atmosphere is naturally less dense). The airfield elevation was 6370 ft, however the density altitude on that day has been calculated to have been 9167 ft, a substantial difference.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="13197" LastEditDate="2018-12-23T22:06:12.960" LastActivityDate="2018-12-23T22:06:12.960" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="1535" PostTypeId="2" ParentId="1531" CreationDate="2014-02-04T13:35:56.000" Score="2" Body="&lt;p&gt;As others have said, yes it can and does happen.  In PHX a few years ago the airport was closed to most aircraft for temperatures at/above 120.  Note please it is not that the planes can't fly in that heat, it is because the planes don't have the proper high density altitude charts so they can't determine how long a runway is needed.  i.e., for part 121 operations such a flight would be illegal.&lt;br&gt;&#xA;Why don't they have the performance tables?  It costs a lot to develop them, and IF they exist, the manufacturers sell them as an extra cost item to the plane's operator.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't believe there is any max temperature limit for the small GA planes that many of us fly, except to say that 120+ degrees is @#&amp;amp;*$# hot in a non-airconditioned GA plane.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-02-04T13:57:53.507" LastActivityDate="2014-02-04T13:57:53.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1536" PostTypeId="1" CreationDate="2014-02-04T14:25:27.743" Score="26" ViewCount="16495" Body="&lt;p&gt;On commercial airlines, I've noticed that the flight attendants always ask everyone to open up their window shades before landing or takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always wondered why this is. Is it something to do with the mechanics of the plane? Is it some kind of passenger-comfort thing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't imagine what difference this act makes, but the attendants seemed really insistent on it. :)&lt;/p&gt;&#xA;" OwnerUserId="801" LastEditorUserId="1696" LastEditDate="2015-10-07T14:39:01.860" LastActivityDate="2015-10-07T14:39:01.860" Title="Why open up the window shades before takeoff and landing?" Tags="&lt;commercial-operations&gt;&lt;windows&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1537" PostTypeId="2" ParentId="1536" CreationDate="2014-02-04T15:21:58.400" Score="33" Body="&lt;p&gt;I'm not sure about other countries, but in the USA there is no FAA requirement mandating that the window shades be open for takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Individual airlines vary in their procedures, with some requiring them to be open while others do not.  This is set by company policy, presumably set by management because they decided that there was/was not a safety benefit in doing so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, I would prefer the window shades to be open all of the time so that even passengers have the chance to point out something that they think might be a problem.  For example, recently a passenger on an airliner &lt;a href=&quot;http://www.nytimes.com/2013/01/09/business/fuel-leak-is-latest-setback-for-boeing-787.html?_r=0&quot; rel=&quot;noreferrer&quot;&gt;noticed a fuel leak&lt;/a&gt; and told a flight attendant about it before the airplane took off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One important thing to keep in mind is that in the event of an emergency evacuation, you should always look out the window before opening an emergency exit to make sure that there isn't a fire or other hazard just outside the door.  This is why a lot of emergency exits don't even have window shades on their windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skeptics.stackexchange.com/a/8853&quot;&gt;This answer on Skeptics.SE&lt;/a&gt; also points out that emergency crews responding to a crash can see through the open windows to better respond and help the people on the airplane.  It also mentions that the passengers eyes will also be more acclimated to the lighting outside the airplane if the window shades are open.  This is also why some airlines have policies requiring the cabin lighting to match the outside light (i.e. the lights will be on bright during the day and dim/out at night).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://travel.stackexchange.com/a/20208&quot;&gt;This answer on Travel.SE&lt;/a&gt; also goes into more detail from a person who works in the airline safety industry.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2014-02-04T15:21:58.400" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1538" PostTypeId="1" AcceptedAnswerId="1569" CreationDate="2014-02-04T17:21:46.557" Score="4" ViewCount="3066" Body="&lt;p&gt;The companies that I have worked for in the past require International Procedures Training like the ones offered by Scott IPC, Flight Safety, CAE Simuflite, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under what conditions is this training required?  (I.e. do I need it to fly to Canada, Mexico, or the Bahamas or is it just to cross the Atlantic/Pacific?)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What regulation requires this training and how often is it required?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-06T10:30:49.830" Title="When is International Procedures Training required?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;international&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1539" PostTypeId="1" AcceptedAnswerId="1540" CreationDate="2014-02-04T17:38:02.207" Score="13" ViewCount="5529" Body="&lt;p&gt;Whenever I sit in an aircraft and we taxi around the airport, I wonder how exactly is the airport organized, for example, the arrangement of the taxiways and runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to locate airport diagrams? I'm mostly interested in Paris CDG, Prague PRG and Amsterdam AMS.&lt;/p&gt;&#xA;" OwnerUserId="802" LastEditorUserId="97" LastEditDate="2014-04-17T22:46:30.347" LastActivityDate="2015-04-11T11:34:01.390" Title="Are the airport &quot;taxi&quot; plans available online?" Tags="&lt;airport&gt;&lt;taxiing&gt;&lt;eu&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1540" PostTypeId="2" ParentId="1539" CreationDate="2014-02-04T17:48:17.673" Score="12" Body="&lt;p&gt;A great site to download airport diagrams and other charts is &lt;a href=&quot;https://charts.aero&quot; rel=&quot;nofollow&quot;&gt;charts.aero&lt;/a&gt;. As of April 2015, however, the site seems gone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport diagrams show all the taxiways and ramps, which is what you are looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that this is an unofficial website. The charts should not be used for actual navigation.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="3386" LastEditDate="2015-04-05T09:40:15.850" LastActivityDate="2015-04-05T09:40:15.850" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1542" PostTypeId="2" ParentId="1539" CreationDate="2014-02-04T17:53:03.913" Score="12" Body="&lt;p&gt;In the US, you can find this on the FAA's website &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/diagrams/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;. You can search for a US Airport, and it will pull up a Airport diagram with Taxiways, Runup areas, and Runways on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find an official guide for European airports, but &lt;a href=&quot;http://www.bostonvirtualatc.com/charts/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; has a detailed &lt;a href=&quot;http://www.bostonvirtualatc.com/charts/index.html?Page=LFPG_index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;guide for CDG&lt;/a&gt;, among others, with a &lt;a href=&quot;http://www.bostonvirtualatc.com/charts/LFPG/AD/AD%202%20LFPG%20OACI%201%20%28Aerodrome%20Chart%29.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;taxiway map&lt;/a&gt; being one component. They also have a similar guide for &lt;a href=&quot;http://www.bostonvirtualatc.com/charts/index.html?Page=EHAM_index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AMS&lt;/a&gt;. They do not have one for PRG. Keep in mind these are unofficial charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/m1PG3.png&quot; alt=&quot;CDG Airport Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Lnafziger noted, &lt;a href=&quot;http://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; also has airport charts, including approaches. The downside is you must register (free) first to access them. You can read more in &lt;a href=&quot;https://aviation.stackexchange.com/a/1277/774&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-02-04T18:00:13.907" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1543" PostTypeId="1" AcceptedAnswerId="1544" CreationDate="2014-02-04T19:50:16.853" Score="57" ViewCount="10014" Body="&lt;p&gt;As per subject, I see that the above mentioned aircraft and some others that have engines mounted on the rear of the fuselage, have the engine intakes tilted slightly upwards. Why has this solution been implemented?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it be better having them parallel to ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airflow of the exhaust is directed slightly towards the ground would't it affect the plane causing it to push the nose downwards?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="22726" LastEditDate="2019-11-06T23:48:33.177" LastActivityDate="2019-11-06T23:48:33.177" Title="Why does the DC-9 have engines that are angled slightly upwards?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;dc-9-family&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="1544" PostTypeId="2" ParentId="1543" CreationDate="2014-02-04T20:16:33.443" Score="70" Body="&lt;p&gt;I believe there this could be traced back to the so-called &lt;strong&gt;downwash angle&lt;/strong&gt; of the air coming off the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the picture below (and put on some imaginary engines on the back like the DC9/MD80), it becomes clear that by mounting it upwards by a few degrees would make it meet the airstream at the streamline angle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Streamlines_around_a_NACA_0012.svg/302px-Streamlines_around_a_NACA_0012.svg.png&quot; alt=&quot;Downwash&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would want to that streamline to interact with the aircraft fan blades with the wind at the same angles. I would imagine that if you did not do this, it would result in an uneven force on the fan blades, which would probably be highly undesirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the drawings of the DC9, it might appear that the shorter version has a higher angle, and that the longer version has a smaller angle, as further from the wing the downwash angle is less, as could also be seen above. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.the-blueprints.com/blueprints-depot/modernplanes/douglas/douglas-dc-9.gif&quot; alt=&quot;DC9&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a little further analysis, the following is apparently off the &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-236280.html&quot; rel=&quot;noreferrer&quot;&gt;DC-9 Manual&lt;/a&gt;, and might shed a little more light on the design, in particular in the last paragraph:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The nacelles have been designed to enclose the JT8D engine with a&#xA;  shape that will allow the highest installed performance ( thrust minus&#xA;  drag ) possible at all flight conditions. The nacelle nose cowling is&#xA;  nonsymmetrical to keep the drag to a minimum at the high mach number&#xA;  cruising conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The nonsymmetry is required to maintain an extremely flat nacelle line&#xA;  adjacent to the fuselage, such that the nacelle supervelocity&#xA;  increments, when added to those from the pylon and fuselage, do not&#xA;  lead to super-critical velocities with resultant shockwave losses.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The nacelle axis and pylon have been set at 3 degrees angle of attack&#xA;  relative to the fuselage to align them with the local flow conditions&#xA;  prevalent at cruising conditions. This is necessary to eliminate the&#xA;  interference and high induced drag that they would otherwise be&#xA;  subjected to. &lt;strong&gt;The nozzle is then canted upward relative to the engine&#xA;  axis, thus eliminating the pitching effects due to thrust&lt;/strong&gt;.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Following picture appears to show the nozzle angle is in fact more horizontal than the entry angle, with the underside longer than the upper side:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://farm4.staticflickr.com/3279/2734260605_33a35bd085_o.jpg&quot; alt=&quot;MD80 engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, while it might not aesthetically pleasing maybe to have it off by a few degrees from the fuselage body, but it does bring advantages when seen with the airflow, and resulting concerns about that the thrust is not being vectored along the body axis is corrected by the nozzle.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.643" LastActivityDate="2014-02-04T22:59:19.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1546" PostTypeId="1" AcceptedAnswerId="1548" CreationDate="2014-02-05T01:00:05.687" Score="8" ViewCount="3295" Body="&lt;p&gt;I remember hearing that special training was required to fly into the Washington DC area and that it didn't really apply to me (maybe it was VFR only?).  What is the requirement and what must you do when flying in the area?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-05T01:09:34.617" LastActivityDate="2014-02-05T01:38:15.240" Title="What special training is required to fly in the Washington DC area?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;flight-planning&gt;&lt;tfr&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1547" PostTypeId="1" AcceptedAnswerId="1560" CreationDate="2014-02-05T01:05:19.443" Score="10" ViewCount="8486" Body="&lt;p&gt;In the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow&quot;&gt;A/FD&lt;/a&gt; for KDCA, it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE: See Special Notices — District of Columbia Ronald Reagan Washington National Airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know that there are special restrictions for flying into DCA, but where is this &quot;Special Notice&quot; that they are referring to, and how can I get permission to fly into DCA under Part 91?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-23T23:35:45.403" LastActivityDate="2014-04-23T23:35:45.403" Title="What requirements are there to fly into KDCA?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1548" PostTypeId="2" ParentId="1546" CreationDate="2014-02-05T01:15:10.440" Score="8" Body="&lt;p&gt;There is a training course on &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=55&amp;amp;preview=true&quot;&gt;FAASafety.gov&lt;/a&gt; that all pilots operating VFR flight within 60nmi of Washington DC must take.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I assume you are flying IFR, you would not be required to take it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Brief-FAA-Special-Awareness-Training-for-the-Washington-D-C-Metropolitan-Area.aspx&quot;&gt;AOPA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All of the following operations are exempt from the training&#xA;  requirement:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Pilots operating under instrument flight rules (IFR);&lt;/li&gt;&#xA;  &lt;li&gt;Law enforcement, military, and aeromedical operations; and&lt;/li&gt;&#xA;  &lt;li&gt;A pilot who must deviate to the extent necessary to address an emergency situation.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="757" LastActivityDate="2014-02-05T01:15:10.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1549" PostTypeId="2" ParentId="1546" CreationDate="2014-02-05T01:16:31.163" Score="6" Body="&lt;p&gt;You are correct.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Starting on February 9, 2009, any pilots flying VFR within a 60 nautical miles (110 km) radius centered on the ADIZ are required to complete training about the ADIZ. This training can be completed online through a course called &amp;quot;Navigating the New DC ADIZ&amp;quot;. Pilots may also complete the required training by attending a seminar offered at a Flight Standards District Office. Pilots must obtain a certificate which proves that the training has been completed. This certificate is not required to be carried with the pilot, but must be produced when requested from law enforcement or other agencies. Pilots flying IFR are not subject to this requirement. [&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/a3a275ddf311d1e0862574a30049e712!OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;src&lt;/a&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is not a TFR, but a permanent special flight rules area. More info can be found &lt;a href=&quot;http://en.wikipedia.org/wiki/Washington,_DC_Metropolitan_Area_Special_Flight_Rules_Area&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; on flying around DC in general.&lt;/p&gt;&#xA;&lt;p&gt;The specific rules can be found in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/a3a275ddf311d1e0862574a30049e712!OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 91.161&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Operations within a 60-nautical mile radius of the Washington, DC VOR/DME under visual flight rules (VFR). Except as provided under paragraph (e) of this section, no person may serve as a pilot in command or as second in command of an aircraft while flying within a 60-nautical mile radius of the DCA VOR/DME, under VFR, unless that pilot has completed Special Awareness Training and holds a certificate of training completion.&lt;/p&gt;&#xA;&lt;p&gt;(b) Special Awareness Training. The Special Awareness Training consists of information to educate pilots about the procedures for flying in the Washington, DC area and, more generally, in other types of special use airspace. This free training is available on the FAA's Web site. Upon completion of the training, each person will need to print out a copy of the certificate of training completion.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-05T01:38:15.240" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1550" PostTypeId="5" CreationDate="2014-02-05T01:16:59.713" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-02-05T01:16:59.713" LastActivityDate="2014-02-05T01:16:59.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1551" PostTypeId="4" CreationDate="2014-02-05T01:16:59.713" Score="0" Body="TFR, or Temporary Flight Restriction is a section of airspace that the FAA has restricted entry into. It is usually issued for airshows and presidential travel." OwnerUserId="757" LastEditorUserId="757" LastEditDate="2014-02-05T01:22:13.967" LastActivityDate="2014-02-05T01:22:13.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1552" PostTypeId="2" ParentId="1547" CreationDate="2014-02-05T01:37:22.690" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ronald_Reagan_Washington_National_Airport#Operations&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; notes (sourced to a TSA page, but page has been moved)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;On October 18, 2005 Ronald Reagan Washington National Airport was reopened to general aviation on a limited basis (48 operations per day) and under restrictions: passenger and crew manifests must be submitted to the Transportation Security Administration 24 hours in advance, and all planes must pass through one of 27 &amp;quot;gateway airports&amp;quot; where re-inspections of aircraft, passengers, and baggage take place. An armed security officer must be on board before departing a gateway airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Brief-GA-Access-Ronald-Reagan-Washington-National-Airport-DCA.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA&lt;/a&gt; has more details, but it does not appear to allow light aircraft, instead restricting flights to only:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;• Operators under a partial security program approved by TSA under 49 CFR 1544.101(b), which operate aircraft with a passenger seating configuration of 31 or more but 60 or fewer seats.&lt;/p&gt;&#xA;&lt;p&gt;• Operators under a Private Charter Standard Security Plan (PCSSP) approved by the TSA under 49 CFR 1544.101(f), which operate aircraft with a passenger seating configuration of 61 or more seats or a maximum certificated takeoff weight of 45,500 kg (101,309 pounds) or more.&lt;/p&gt;&#xA;&lt;p&gt;• Operators in scheduled or charter service with a Twelve Five Standard Security Plan (TFSSP) approved by TSA under 49 CFR 1544.101(d), which operate aircraft with a maximum certificated takeoff weight of greater than 12,500 pounds.&lt;/p&gt;&#xA;&lt;p&gt;• Aircraft operated by corporations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The process overview at the linked AOPA page is fairly detailed, but involves several applications, a background check, passenger lists, and more. In addition, the flight must &lt;em&gt;originate from a gateway airport, not just any airfield&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-05T01:37:22.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1553" PostTypeId="1" AcceptedAnswerId="1555" CreationDate="2014-02-05T02:16:33.010" Score="13" ViewCount="24301" Body="&lt;p&gt;I do a lot of shortwave radio listening, and I often listen to MWARA air traffic radio transmissions based out of San Francisco for flights crossing the Pacific Ocean. When giving position reports the pilots always report fuel, position, and some strange names. Usually they give the strange name, and then report &quot;NEXT --strange name here--&quot;. Some of the names I've heard are &quot;Diallo&quot;, &quot;Gallop&quot;, &quot;Gitsol&quot; (sp?). What are these?&lt;/p&gt;&#xA;" OwnerUserId="810" LastEditorUserId="64" LastEditDate="2014-02-05T18:11:24.020" LastActivityDate="2019-03-22T12:42:35.137" Title="What are pilot position reports?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;navigation&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1554" PostTypeId="2" ParentId="1553" CreationDate="2014-02-05T02:41:27.547" Score="5" Body="&lt;p&gt;These names probably sound like you spelled them, but are all five-letter codes describing a fixed coordinate. For example 'MNATE' = manatee, but there are also many of those you can't really pronounce. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's now explain the use of them: Air traffic control needs to know where you are planning to go and also needs to be able to send you to specific positions in order to maintain a safe and efficient traffic flow. Now they can't say &quot;turn right at the next lights and then take the third left&quot; so we need to build our own &quot;streets&quot;. Therefore we use radio beacons on the surface and GPS fixes. Obviously it it would be hard to build and maintain a radio beacon somewhere far out in the pacific so the majority of the fixes out there are defined by coordinates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why do they use these strange names? Well, THNDR even as &quot;Tango-Hotel-November-Delta-Romeo&quot; is easier to comunicate than Nort 20° 15.5 West 100° 12.3, isn't it? In aviation our GPS systems also use a common data base, which is updated by a fixed shedule. So, other than in your car, we also have all the up-to-date locations and pilots don't have to put in x-digit coordinates but only five-digit waypoints.&lt;/p&gt;&#xA;" OwnerUserId="343" LastActivityDate="2014-02-05T02:41:27.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1555" PostTypeId="2" ParentId="1553" CreationDate="2014-02-05T02:43:12.667" Score="19" Body="&lt;h1&gt;Navigation Fixes&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The words that you are hearing are navigation fixes that are published on the pacific crossing charts.  They are used so that aircraft can report their position to Air Traffic Control using a standard, easy to say name that is located at a specific geographic location.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can think of them like street intersections.  Instead of saying &lt;strong&gt;&lt;em&gt;29 degrees 44 minutes 18.8 seconds North, 95 degrees 24 minutes 38.5 seconds West&lt;/em&gt;&lt;/strong&gt; (GPS coordinates), you would say &lt;strong&gt;&lt;em&gt;the intersection of South Shepherd Drive and West Alabama Street&lt;/em&gt;&lt;/strong&gt;&lt;sup&gt;1&lt;/sup&gt;.  In the case of aviation though, they take it one step further and give it a five letter (usually) pronounceable name like the ones that you are hearing on the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navigation fixes that you refer to are standard reporting points located on airways going between the SW coast of the US to/from Hawaii:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GALIP and DIALO are on R576 (outbound airway)&lt;/li&gt;&#xA;&lt;li&gt;GITLE is on R585 (inbound airway)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To see an actual chart and to follow along, the FAA offers &lt;a href=&quot;http://aeronav.faa.gov/digital_enroute_planning.asp?eff=02-06-2014&amp;amp;end=04-03-2014&quot; rel=&quot;noreferrer&quot;&gt;IFR Enroute Aeronautical Planning Charts&lt;/a&gt; on their website (these would be on the PORC chart).  Here is a low resolution excerpt from the area that we are talking about:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JTUgm.jpg&quot; alt=&quot;PORC Chart Excerpt CA-HI&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical flight will file an airway with only the start and end fixes along with the airway name instead of specifying every fix on the route.  For instance, it might look something like &lt;code&gt;GALIP R576 OGG&lt;/code&gt; which tells ATC that they will fly directly between all of the fixes on the airway: &lt;code&gt;GALIP DADIE DIALO DUSAK DRAYK DENNS OOG&lt;/code&gt;.  The filled in triangle at each of these fixes means that it is a &lt;strong&gt;&lt;em&gt;mandatory&lt;/em&gt;&lt;/strong&gt; reporting point, and they will be required to make a position report every time that they cross one.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Position Reports&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Position reports are given in a standard format specified in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0503.html#6bG96JACK&quot; rel=&quot;noreferrer&quot;&gt;AIM 5-3-2&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;d. Position Report Items:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. Position reports should include the following items:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Identification;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Position;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Time;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Altitude or flight level (include actual altitude or flight level&#xA;  when operating on a clearance specifying VFR-on-top);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Type of flight plan (not required in IFR position reports made&#xA;  directly to ARTCCs or approach control);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) ETA and name of next reporting point;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) The name only of the next succeeding reporting point along the&#xA;  route of flight; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) Pertinent remarks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Example (from 5-3-1):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(Name) CENTER, (aircraft identification), (position), (time),&#xA;  (altitude), (type of flight plan), (ETA and name of next reporting&#xA;  point), (the name of the next succeeding reporting point), AND&#xA;  (remarks).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Or a better example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Los Angeles Center, N1234, over GALIP at 1645, Flight Level 370, Estimating DADIE at 1730, DIALO next&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Then, when they get to DADIE, they do it all over again:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Los Angeles Center, N1234, over DADIE at 1730, Flight Level 370, Estimating DIALO at 1818, DUSAK next&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This continues until the aircraft is identified on radar again at which time they can discontinue reporting unless specifically requested by ATC.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Mapped &lt;a href=&quot;https://www.google.com/maps/place/29%C2%B044%2718.8%22N+95%C2%B024%2738.5%22W/@29.738556,-95.410698,95m/data=!3m1!1e3!4m2!3m1!1s0x0:0x0&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; for the curious.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-14T05:53:40.593" LastActivityDate="2014-02-14T05:53:40.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1556" PostTypeId="2" ParentId="1553" CreationDate="2014-02-05T02:58:08.550" Score="8" Body="&lt;p&gt;The names that you mention are reporting points.  The aircraft that you're hearing are not visible on radar by air traffic control, so they're reporting their location so that ATC can keep track of them.  The specific format of the call they're making is &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0503.html&quot;&gt;published in the AIM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1. Position reports should include the following items:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Identification;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Position;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Time;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Altitude or flight level (include actual altitude or flight level&#xA;  when operating on a clearance specifying VFR-on-top);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Type of flight plan (not required in IFR position reports made&#xA;  directly to ARTCCs or approach control);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) ETA and name of next reporting point;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) The name only of the next succeeding reporting point along the&#xA;  route of flight; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) Pertinent remarks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-02-05T02:58:08.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1557" PostTypeId="1" AcceptedAnswerId="1558" CreationDate="2014-02-05T03:30:23.913" Score="15" ViewCount="1602" Body="&lt;p&gt;When flying on a long-haul flight, you can often see gate allocations for when you land a hour or two before actually arriving at the airport, including transfer information and connecting flights. However, with so many aircraft and frequently changing situations, how do they manage to allocate these gates so far out in advance?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="69" LastEditDate="2014-02-05T03:40:01.330" LastActivityDate="2014-02-05T05:17:29.050" Title="How are airlines able to work out gate allocations so far in advance?" Tags="&lt;airport&gt;&lt;airline-operations&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1558" PostTypeId="2" ParentId="1557" CreationDate="2014-02-05T03:33:37.770" Score="11" Body="&lt;p&gt;Route times are pretty well known. If you know when the plane should depart and how long the flight should last, it's pretty easy to calculate when it will be arriving. Give a few minutes leeway on either side, and you should be good. If the plane is not there on time, you send it somewhere else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most large aircraft have some sort of &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot;&gt;ACARS&lt;/a&gt; that allows them to talk to company dispatch and let them know if they're going to be early or late, among other things. Barring that, they almost always have a company radio frequency that they can relay messages on one way or another.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-02-05T05:17:29.050" LastActivityDate="2014-02-05T05:17:29.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1559" PostTypeId="2" ParentId="1539" CreationDate="2014-02-05T06:49:48.880" Score="6" Body="&lt;p&gt;If you look up the ICAO code, e.g. here &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code&quot;&gt;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;then Google for the code + charts, e.g &quot;EGLL charts&quot;, you will usually find what you're looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.co.uk/search?q=egll+charts&quot;&gt;https://www.google.co.uk/search?q=egll+charts&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2014-02-05T06:49:48.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1560" PostTypeId="2" ParentId="1547" CreationDate="2014-02-05T07:28:03.113" Score="14" Body="&lt;p&gt;The &amp;quot;special notices&amp;quot; are a section of the &lt;a href=&quot;http://aeronav.faa.gov/afd/06FEB2014/NE_rear_06FEB2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;A/FD&lt;/a&gt;, but those notices paint a very incomplete picture. Both the FAA and the TSA have requirements regarding DCA. The very basics are that you must get authorization from both the FAA and TSA 24 hours in advance, you must have an armed security officer, and you must depart from a &lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/dassp_gatewaylist_3-21-2013.pdf&quot; rel=&quot;noreferrer&quot;&gt;gateway airport&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The details are, well...&lt;/p&gt;&#xA;&lt;h2&gt;FAA Requirements&lt;/h2&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Regulations require an arrival/departure slot to be reserved via the &lt;a href=&quot;https://www.fly.faa.gov/ecvrs/index.html&quot; rel=&quot;noreferrer&quot;&gt;e-CVRS&lt;/a&gt; system during most hours, just like other airports designated as high-density airports.&lt;/li&gt;&#xA;&lt;li&gt;Flights to DCA must originate from within a 1250 mile perimeter (with limited exceptions).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;TSA requirements&lt;/h2&gt;&#xA;&lt;p&gt;The TSA requirements are referred to as the DCA Access Standard Security Program (DASSP). An overview is given on this &lt;a href=&quot;http://www.tsa.gov/stakeholders/security-programs-and-initiatives&quot; rel=&quot;noreferrer&quot;&gt;tsa.gov page&lt;/a&gt; (scroll down to &amp;quot;DCA Access Standard Security Program&amp;quot;).&lt;/p&gt;&#xA;&lt;p&gt;Details can be found in the &lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/inerim_final_rule_v2.pdf&quot; rel=&quot;noreferrer&quot;&gt;Interim Final Rule&lt;/a&gt;... because calling the ruling both &lt;em&gt;interim&lt;/em&gt; and &lt;em&gt;final&lt;/em&gt; won't confuse anyone. Here is a summarization of that document:&lt;/p&gt;&#xA;&lt;h3&gt;Section A. Aircraft Operator Requirements:&lt;/h3&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Security Coordinators&lt;/strong&gt; The aircraft operator (company) must have a designated security coordinator who is the point of contact for the TSA and is responsible for implementing the DASSP requirements. This person must undergo a TSA security threat assessment, and a fingerprint-based criminal history records check (CHRC) by the FBI.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;DCA Access Standard Security Program (DASSP)&lt;/strong&gt; TSA will verify the operator's status with the FAA before sending the DASSP document which contains &amp;quot;sensitive security information&amp;quot; which must be implemented, and the operator must notify TSA when all requirements have been implemented.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Flightcrew Members&lt;/strong&gt; Each flight crew member (does not include flight attendants) must undergo a fingerprint-based CHRC and an FAA record check. Almost any prior restricted airspace violation is an immediate disqualifier.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Flight Approvals&lt;/strong&gt; Each flight into or out of DCA requires a tentative slot reservation from the FAA (see FAA reqirement #1 above) before applying for TSA authorization. The TSA application must be submitted at least 24 hours prior to aircraft departure. If TSA approves the application, they will transmit this to the FAA which will issue the final slot reservation, and TSA will notify the operator. The &lt;strong&gt;TSA only approves up to 48 applications&lt;/strong&gt; for a given date. The application must include (once per round-trip):&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The name, address, and citizen status of each passenger and crewmember (includes flight attendants).&lt;/li&gt;&#xA;&lt;li&gt;The registration number of the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The flight plan.&lt;/li&gt;&#xA;&lt;li&gt;and... &amp;quot;any other information required by TSA.&amp;quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Operating Requirements&lt;/strong&gt; Each flight must:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;be operated under instrument flight rules.&lt;/li&gt;&#xA;&lt;li&gt;not make any intermediate stops between the designated gateway airport and DCA.&lt;/li&gt;&#xA;&lt;li&gt;have the aircraft, crew, passengers, and property inspected by TSA prior to departure.&lt;/li&gt;&#xA;&lt;li&gt;have the cockpit door closed and locked for the duration of the flight (if equipped).&lt;/li&gt;&#xA;&lt;li&gt;have at least one armed security officer who meets the armed security officer requirements.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Costs&lt;/strong&gt; TSA charges \$15 for each crew member and passenger to conduct the security threat assessment. Additionally, they charge for the screening services at the airport which are &amp;quot;currently estimated at \$296 per round trip into and out of DCA.&amp;quot;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Protection of Sensitive Security Infonnation&lt;/strong&gt; The specific security details described in the DASSP must only be shared on a need-to-know basis.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Other Security Procedures&lt;/strong&gt; This paragraph basically says TSA can make you do whatever they want... as if that wasn't obvious by this point in the list.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Compliance&lt;/strong&gt; TSA can perform any inspection or test it wants to verify the operators compliance with DASSP.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;h3&gt;Section B. Fixed Base Operator Requirements&lt;/h3&gt;&#xA;&lt;p&gt;&lt;em&gt;That's right, there are two section B's, one right after the other... in case you weren't already convinced the TSA has strong attention to detail.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;This section just says there are FBO requirements for gateway airports. Here is a list of &lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/dassp_gatewaylist_3-21-2013.pdf&quot; rel=&quot;noreferrer&quot;&gt;Gateway Airports&lt;/a&gt; dated March 21, 2013. The list is always subject to change and seems to have more to do with whether there is an FBO at the airport who wants to put up the DASSP more than anything else.&lt;/p&gt;&#xA;&lt;h3&gt;Section C. Armed Security Officer Requirements&lt;/h3&gt;&#xA;&lt;p&gt;Armed security officers must be an active or retired law enforcement officer, or an individual approved by the TSA. This requires a similar background check as the security coordinator and law enforcement training which TSA finds acceptable. For more information, see the &lt;a href=&quot;http://www.tsa.gov/about-tsa/armed-security-officer-aso-program&quot; rel=&quot;noreferrer&quot;&gt;Armed Security Officer (ASO) Program&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Flying under Part 91?&lt;/h3&gt;&#xA;&lt;p&gt;At first glance it doesn't seem like there is any rule explicitly prohibiting Part 91 operations in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5e655959da7dab4ee420e2f5192708b4&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5&quot; rel=&quot;noreferrer&quot;&gt;49 CFR Part 1544&lt;/a&gt;, and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5e655959da7dab4ee420e2f5192708b4&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5#49:9.1.3.5.11.1.10.1&quot; rel=&quot;noreferrer&quot;&gt;§1544.1 Applicability of this part.&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) This part prescribes aviation security rules governing the following:&lt;/p&gt;&#xA;&lt;p&gt;(1) The operations of aircraft operators holding operating certificates under 14 CFR part 119 for scheduled passenger operations, public charter passenger operations, private charter passenger operations; the operations of aircraft operators holding operating certificates under 14 CFR part 119 operating aircraft with a maximum certificated takeoff weight of 12,500 pounds or more; &lt;strong&gt;and other aircraft operators adopting and obtaining approval of an aircraft operator security program.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The general definition of an &lt;em&gt;aircraft operator&lt;/em&gt; is not limited to an operator with a Part 119 operating certificate. &lt;strong&gt;However, the possibility of using part 91 seems to be ruled out&lt;/strong&gt; by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5e655959da7dab4ee420e2f5192708b4&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5#49:9.1.3.5.11.2.10.1&quot; rel=&quot;noreferrer&quot;&gt;§1544.101 Adoption and implementation.&lt;/a&gt; where it enumerates the scenarios TSA is willing to approve, and there are no Part 91 operations in the list.&lt;/p&gt;&#xA;&lt;p&gt;There are probably a few reasons why Part 91 is not allowed. Most notably:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;TSA has specific aircraft operator requirements which an individual operator is unlikely to be able to comply with, and&lt;/li&gt;&#xA;&lt;li&gt;There are only 48 slots available per day, and therefore preference is given to commercial operators - the explicitly given explanation for why non-airline flights are permitted at all is to permit &amp;quot;operators, their customers, and affected local businesses to recover from the adverse economic impacts brought on by the events of September 11, 2001.&amp;quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Other fun quotes:&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TSA may, at its discretion, require any flight into or out of DCA under this subpart to comply with additional security measures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and...&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In addition, if TSA or the FAMS requires that the aircraft have one or more Federal Air Marshals (FAMs) on board, the aircraft operator must allow the FAM(s) onboard, at no cost to the Federal Government.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and...&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TSA may, at its discretion, &lt;strong&gt;cancel any or all flight approvals at any time&lt;/strong&gt; without prior notice to the aircraft operator. For example, if the threat level in the Washington, D.C., area or in the vicinity of any of the gateway airports is set at ORANGE or RED, TSA is likely to cancel any and all flight approvals into and out of DCA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, happy flying everyone!&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-23T12:37:49.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1561" PostTypeId="2" ParentId="205" CreationDate="2014-02-05T12:36:05.850" Score="1" Body="&lt;p&gt;This &lt;a href=&quot;http://adsb.tc.faa.gov/WG3_Meetings/Meeting8/Squitter-Lon.pdf&quot; rel=&quot;nofollow&quot; title=&quot;MIT Presentation&quot;&gt;MIT paper&lt;/a&gt; is a bit dated, but very technical information about the ADS-B protocol for the tinkerer in you.&lt;/p&gt;&#xA;" OwnerUserId="795" LastActivityDate="2014-02-05T12:36:05.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1562" PostTypeId="1" CreationDate="2014-02-05T13:52:38.353" Score="31" ViewCount="65625" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=fVq4_HhBK8Y&quot;&gt;In &lt;em&gt;Airplane&lt;/em&gt; there is a famous sequence:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Roger Murdock: Flight 2-0-9'er, you are cleared for take-off.&#xA;Captain Oveur: Roger!&#xA;Roger Murdock: Huh?&#xA;Tower voice: L.A. departure frequency, 123 point 9'er.&#xA;Captain Oveur: Roger!&#xA;Roger Murdock: Huh?&#xA;Victor Basta: Request vector, over.&#xA;Captain Oveur: What?&#xA;Tower voice: Flight 2-0-9'er cleared for vector 324.&#xA;Roger Murdock: We have clearance, Clarence.&#xA;Captain Oveur: Roger, Roger. What's our vector, Victor?&#xA;Tower voice: Tower's radio clearance, over!&#xA;Captain Oveur: That's Clarence Oveur. Over.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Regardless of the silly dialogue, when the captain asks &quot;What's our vector, Victor?&quot; what is he referring to? Does the scene refer to actual issues that one might discuss with air traffic control?&lt;/p&gt;&#xA;" OwnerUserId="339" LastEditorUserId="1696" LastEditDate="2015-04-28T15:10:23.740" LastActivityDate="2020-03-10T18:02:17.947" Title="&quot;What's our vector, Victor?&quot;: What does this mean?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1563" PostTypeId="2" ParentId="1562" CreationDate="2014-02-05T14:17:53.673" Score="14" Body="&lt;p&gt;A &lt;em&gt;vector&lt;/em&gt; refers to a heading given by Air Traffic Control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to start learning aviation phraseology, there might be better sources out there:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://contentzone.eurocontrol.int/phraseology/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Say again&lt;/em&gt; phraseology database&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/115.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;All clear&lt;/em&gt; phraseology manual&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is some resemblance of reality but a number of things are mixed up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of replying with a 'roger', safety critical information is read back. This allows ATC to confirm that the instruction is clearly understood and if necessary they can correct errors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scene describes a take-off. In normal life, and assuming this is controlled airspace, the crew will like to know what to do after getting airborne before they start their take-off roll. There is no point in taking off if you are not allowed to fly in the airspace above the airport. That is why the departure clearance (here &quot;vector 324&quot;) will be  issued first. Vectors will be given as &quot;heading&quot;. Very often the departure clearance is a standard route instead of vectors. (e.g. LEKKO two alpha departure). On large airports, departure clearances are given on a separate frequency to avoid congestion on the ground and tower frequencies. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Departure clearance&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tower&lt;/strong&gt;: Fiction two zero niner, after departure, turn right heading three two five, climb and maintain six thousand feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FIC209&lt;/strong&gt;: After departure heading three two five, 6000 ft. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Take-off clearance&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tower&lt;/strong&gt;: Fiction two zero niner, runway 27, cleared for take-off&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FIC209&lt;/strong&gt;: Cleared for take-off runway 27, Fiction two zero niner.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Hand over to departure frequency&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tower&lt;/strong&gt;: Fiction two zero niner, contact departure one two three decimal niner&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FIC209&lt;/strong&gt;: Departure on one two three decimal niner, Fiction two zero niner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FIC209&lt;/strong&gt;: L.A. departure, Fiction two zero niner one thousand climbing six thousand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Departure&lt;/strong&gt;: Fiction two zero niner, radar contact, maintain present heading, climb and maintain ten thousand&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FIC209&lt;/strong&gt;: climbing ten thousand,  Fiction two zero niner&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, when on the tower frequency, the words &quot;take-off&quot;, and &quot;cleared&quot; are only used when the actual take-off clearance is given. This is to avoid (catastrophic) confusion. &#xA;Since &quot;After take-off&quot; cannot be used, instead the phrase &quot;after departure&quot; or &quot;when airborne&quot; is used. &lt;/p&gt;&#xA;&#xA;&#xA;" OwnerUserId="19" LastEditorUserId="13197" LastEditDate="2020-03-10T18:02:17.947" LastActivityDate="2020-03-10T18:02:17.947" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1564" PostTypeId="1" AcceptedAnswerId="1567" CreationDate="2014-02-05T14:26:36.193" Score="26" ViewCount="11345" Body="&lt;p&gt;Some aircraft such as the DHC-6 Twin Otter, have their throttles on the overhead panel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OMeYC.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason that they are not on a center console between the pilot seats or mounted to the panel like on most airplanes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like it would be more comfortable for the pilot if he didn't have to reach up to change the power settings.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-03-17T05:37:25.920" LastActivityDate="2018-12-30T22:34:26.687" Title="Why are the throttles of aircraft such as the Twin Otter placed on the overhead panel?" Tags="&lt;aircraft-design&gt;&lt;throttle&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1565" PostTypeId="2" ParentId="1564" CreationDate="2014-02-05T15:08:37.913" Score="3" Body="&lt;p&gt;In the case of a high wing multi engine plane, like the Grumman seaplanes, the distance and a less convoluted path for a steel cable from the throttle control to the engine may have a lot to do with this design choice.  However, this is a guess completely unencumbered with facts.....&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-02-05T21:33:54.450" LastActivityDate="2014-02-05T21:33:54.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1566" PostTypeId="2" ParentId="1562" CreationDate="2014-02-05T15:19:00.063" Score="24" Body="&lt;p&gt;A vector is defined by a direction and magnitude.  In aviation these represent your heading (the direction) and your speed (the magnitude).  However, in normal aviation usage &quot;vector&quot; only refers to the heading and other nomenclature is used to assign/report speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Jetlink 1234, Cleveland Center, turn left heading 250 for traffic&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In which case the vector assigned by ATC is 250 degrees, or 20 degrees south of magnetic west.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question &quot;What is our vector, Victor?&quot;, Victor should state the heading they have been assigned to fly from ATC.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An alternative question would be &quot;What is your heading?&quot; and then you would answer with the direction you are currently flying.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-05-01T16:11:36.673" LastActivityDate="2015-05-01T16:11:36.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1567" PostTypeId="2" ParentId="1564" CreationDate="2014-02-05T15:57:13.930" Score="25" Body="&lt;p&gt;I think it was for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It makes for straight path for the controls to reach the engines, as all of these are fly by cable. Many of these aircraft where also designed for harsh climates, so I imagine it's an advantage to have less pulleys and other things which might rust and require maintenance. &lt;/li&gt;&#xA;&lt;li&gt;There is very little space to place the throttles further down, especially with the control column mounted on the DHC6 Twin Otter where it is. If you did want a pedestal, you'd have to seperate the control columns, requiring further mechanical components, and you'd have to route the engine cables upwards, both of which would be undesirable.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a7iLG.jpg&quot; alt=&quot;Twin Otter Cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you mentioned, there are downsides. Commonly mentioned ones are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is not particularly comfortable to have you arm raised for an extended period of time, and you lose some sensitivity in it.&lt;/li&gt;&#xA;&lt;li&gt;You hope that the other pilot used his deodorant that morning.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other somewhat similar aircraft which use this configuration are the PBY Catalina and Grumman Goose. Another one is the Avro York heavy transport aircraft.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2018-12-30T22:34:26.687" LastActivityDate="2018-12-30T22:34:26.687" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="1568" PostTypeId="2" ParentId="1564" CreationDate="2014-02-05T18:16:43.410" Score="17" Body="&lt;p&gt;Overhead throttles are a pretty common thing in seaplanes (see the picture in &lt;a href=&quot;https://aviation.stackexchange.com/a/1567/64&quot;&gt;Manfred's answer&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This actually came up as an &lt;a href=&quot;http://www.youngeagles.org/questions/afmviewfaq.asp?faqid=1579&quot; rel=&quot;noreferrer&quot;&gt;EAA Young Eagles FAQ&lt;/a&gt; and in addition to the reasons Manfred gave the Grumman engineer they spoke to gave an explanation I'd not heard before:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;…first and foremost, the reason the throttle are overhead is due to a physiological issue related to the g-forces encountered during water landings. At times, forces as high as 3 Gs can be registered on contact with the water, and by having the throttles hanging down from a pivot point above, it's nearly impossible for the hand of the pilot to bend the throttle.&lt;br&gt;&#xA;  When the downward force is encountered, the pilot's hands will move downward as well, so the force is applied to the throttle in a way that will not damage the linkage, and it will not likely result in an abrupt throttle position change. With a panel mounted throttle, it's likely that a higher-G landing on the water (or on the deck of a carrier) would result in a bent throttle. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-02-05T18:16:43.410" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1569" PostTypeId="2" ParentId="1538" CreationDate="2014-02-05T20:33:55.453" Score="3" Body="&lt;p&gt;I have never heard of a specific &quot;International Procedures&quot;  program/rating. However, this was taken from one of the websites offering this training:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;it will satisfy the training requirements needed for MNPS, RVSM,&#xA;  RNP-4, RNP-10, B-RNAV and P-RNAV Special Use Airspace approvals&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My guess is this course is offered as a bundle of MNPS/RVSM/RNAV training programs to the operators. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the operator to be certified to fly in MNPS airspace, they need to have a specific authorization from the regulating authority (in FAA they specifically need OpSpecB039) which in turn, requires specific training programs for the pilots. The same is valid about operation in RVSM,RNAV,etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no specific recurency training period; however, each approval certificate, for each specific operator, must include an approved 'initial and recurrent training program' which will specify the training frequency. At most, these periods must abide &#xA;by the operator's program for proficiency check and line checks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;8900.1 4.1.4 98(d)&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NAT/MINIMUM NAVIGATION PERFORMANCE SPECIFICATIONS (MNPS) AIRSPACE.  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Each  aircraft is suitably equipped and capable of meeting the MNPS standards.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The operator has established operating procedures that&#xA;  ensure that MNPS standards are met. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;&lt;strong&gt;The flightcrews are trained and capable of operating to MNPS requirements&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All NAT/MNPS approvals are granted by issuing OpSpec paragraph B039,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO NAT Doc 007 § 1.2.1&lt;/strong&gt; (I'm really not an FAA guy, somebody might find the Part 135 / 91 equivalent)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All flights within NAT MNPS Airspace must have the approval of either&#xA;  the State of Registry of the aircraft, or the State of the&#xA;  Operator[...] These aspects include: the navigation equipment used,&#xA;  together with its installation and maintenance procedures; plus the&#xA;  crew navigation procedures employed &lt;strong&gt;and the crew training&#xA;  requirements&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;The ICAO doc goes on to further detail what that training should include (1.3.8 - &gt; 1.3.12), but does not specify a training frequency or the need for recurrent training.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Appendix G to Part 91: Operations in Reduced Vertical Separation Minimum (RVSM) Airspace&lt;/strong&gt;&#xA;Section 3 Operator Authorization &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b)An applicant for authorization to operate within RVSM airspace&#xA;  shall apply in a form and manner prescribed by the Administrator. The&#xA;  application must include the following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For an applicant who operates under part 121 or 135 of this chapter or under subpart K of this part, &lt;strong&gt;initial and recurring pilot&#xA;  training&lt;/strong&gt; requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;AMC1 SPA.RVSM.105 RVSM operational approval&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Training programmes, operating practices and procedures :&#xA;      The operator should submit training syllabi for &lt;strong&gt;initial and recurrent training  programmes&lt;/strong&gt; together with other relevant material.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-02-06T10:30:49.830" LastActivityDate="2014-02-06T10:30:49.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1571" PostTypeId="1" CreationDate="2014-02-05T21:28:27.707" Score="16" ViewCount="2332" Body="&lt;p&gt;Sorry for the slightly strange question, but Ryanair (Europe's Largest Low Cost Carrier) decided that seat back pockets took too much effort and got rid of them, and it appears the sick bags in the process.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pqkAh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pqkAh.jpg&quot; alt=&quot;Ryanair Interior&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://poloconghaile.com/wp-content/uploads/2013/10/Ryanair-flight-interior.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;poloconghaile.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;So the question comes up...&lt;/p&gt;&#xA;&lt;p&gt;What happens &lt;strong&gt;when Ryanair flights encounter turbulence&lt;/strong&gt;? I can hardly imagine the Flight Attendants handing out bags ad-hoc when it's sufficiently shaky to cause motion sickness among the passengers.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2020-12-19T15:00:00.243" LastActivityDate="2020-12-19T15:00:00.243" Title="What does Ryanair do without Sick Bags?" Tags="&lt;commercial-aviation&gt;&lt;ryanair&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="1572" PostTypeId="1" CreationDate="2014-02-06T00:50:01.170" Score="10" ViewCount="1721" Body="&lt;p&gt;If a pilot has the opportunity to fly as an SIC in a private jet, what FAA requirements must they comply with in order to fly with passengers?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-18T12:56:40.883" Title="What does a pilot have to do in order to fly as a second in command in a private jet?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1573" PostTypeId="1" AcceptedAnswerId="1576" CreationDate="2014-02-06T00:52:33.697" Score="11" ViewCount="8720" Body="&lt;p&gt;What can I do if my not-so-newly issued temporary pilot certificate is about to expire and I haven't gotten my permanent certificate yet?  Is there any way that I can keep flying while waiting for it, and is there a way to check on the status of the permanent certificate?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-06T01:59:06.490" LastActivityDate="2016-04-28T18:19:03.373" Title="What happens when a temporary pilot certificate expires?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1574" PostTypeId="1" AcceptedAnswerId="1575" CreationDate="2014-02-06T01:04:53.087" Score="12" ViewCount="1996" Body="&lt;p&gt;If a pilot wishes to obtain an initial FAA type rating - say, for a Boeing 737 - are the requirements to obtain that rating the same as if they were getting a type rating for an Airbus A320? If they are different, where can these requirements be found?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume that in both cases the pilot is ATP-rated.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="69" LastEditDate="2014-02-17T18:34:27.497" LastActivityDate="2014-02-17T18:34:27.497" Title="Are the requirements for an initial type rating the same across types?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1575" PostTypeId="2" ParentId="1574" CreationDate="2014-02-06T01:16:41.517" Score="11" Body="&lt;p&gt;Actually, it doesn't matter whether you are a Private pilot or an ATP, the requirements for a type rating are in the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-5F.pdf&quot;&gt;Airline Transport Pilot and Aircraft Type Rating Practical Test Standards&lt;/a&gt;, which apply regardless of the aircraft type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the PTS, it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Practical Test Book Description&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This practical test book contains the Airline Transport Pilot and &#xA;  Aircraft Type Rating Practical Test Standards—Airplane.  The Airline&#xA;  Transport Pilot and Aircraft Type Rating Practical Test &#xA;  Standards—Airplane includes Areas of Operation and Tasks for the &#xA;  initial issuance of an airline transport pilot certificate and for the&#xA;  addition of category, class, and aircraft type ratings to an airline &#xA;  transport pilot certificate. These Areas of Operation and Tasks also &#xA;  apply for the issuance of an airplane type rating to a private or &#xA;  commercial pilot certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You basically cover everything needed for the ATP.  The differences between the different airplanes come out during the practical test just like they do for any other checkride.  The examiner (who will be typed in the airplane) asks you about the things that are specific to each airplane, but this isn't really a lot different than him asking you questions specific to a Cessna or a Piper during your private pilot checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTS specifies general &lt;em&gt;Areas of Operation&lt;/em&gt;'s instead of saying exactly what needs to be tested for every aircraft type. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here they are for a type rating:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Section 1: Preflight Preparation&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Areas of Operation&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;I. Preflight Preparation&lt;br&gt;&#xA;  Task A: Equipment Examination&lt;br&gt;&#xA;  Task B: Performance and Limitations &#xA;  Task C: Water and Seaplane Characteristics (AMES/ASES)&lt;br&gt;&#xA;  Task D: Seaplane Bases, Maritime Rules, and Aids to Marine Navigation (AMES/ASES)  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Section 2: Preflight Procedures, Inflight Maneuvers, and Postflight Procedures&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Areas of Operation&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;II. Preflight Procedures&lt;br&gt;&#xA;  Task A: Preflight Inspection&lt;br&gt;&#xA;  Task B: Powerplant Start &#xA;  Task C: TAXIING &#xA;  Task D: Sailing (AMES/ASES)&lt;br&gt;&#xA;  Task E: Seaplane Base/Water Landing Site Markings and Lighting (AMES, ASES)&lt;br&gt;&#xA;  Task F: Pre-Takeoff Checks  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;III. Takeoff and Departure Phase&lt;br&gt;&#xA;  Task A: Normal and Crosswind Takeoff&lt;br&gt;&#xA;  Task B: Glassy Water Takeoff and Climb (AMES/ASES)&lt;br&gt;&#xA;  Task C: Rough Water Takeoff and Climb (AMES/ASES)&lt;br&gt;&#xA;  Task D: Confined-Area Takeoff and Climb (AMES/ASES)&lt;br&gt;&#xA;  Task E: Instrument Takeoff&lt;br&gt;&#xA;  Task F: Powerplant Failure during Takeoff&lt;br&gt;&#xA;  Task G: Rejected Takeoff&lt;br&gt;&#xA;  Task H: Departure Procedures &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;IV. Inflight Maneuvers&lt;br&gt;&#xA;  Task A: Steep Turns&lt;br&gt;&#xA;  Task B: Approaches to Stalls and Stall Recovery&lt;br&gt;&#xA;  Task C: Powerplant Failure—Multiengine Airplane&lt;br&gt;&#xA;  Task D: Powerplant Failure—Single–Engine Airplane&lt;br&gt;&#xA;  Task E: Specific Flight Characteristics&lt;br&gt;&#xA;  Task F: Recovery from Unusual Attitudes  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;V. Instrument Procedures&lt;br&gt;&#xA;  Task A: Standard Terminal Arrival/Flight Management System Procedures&lt;br&gt;&#xA;  Task B: Holding&lt;br&gt;&#xA;  Task C: Precision Approaches (PA) &#xA;  Task D: Nonprecision Approaches (NPA)&lt;br&gt;&#xA;  Task E: Circling Approach &#xA;  Task F: Missed Approach  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;VI. Landings and Approaches to Landings&lt;br&gt;&#xA;  Task A: Normal and Crosswind Approaches and Landings&lt;br&gt;&#xA;  Task B: Landing from a Precision Approach&lt;br&gt;&#xA;  Task C: Approach and Landing with (Simulated) Powerplant Failure—Multiengine Airplane&lt;br&gt;&#xA;  Task D: Landing From a Circling Approach&lt;br&gt;&#xA;  Task E: Rough Water Approach and Landing (AMES/ASES)&lt;br&gt;&#xA;  Task F: Glassy Water Approach And Landing (AMES/ASES) &#xA;  Task G: Confined-Area Approach and Landing (AMES/ASES)&lt;br&gt;&#xA;  Task H: Rejected Landing&lt;br&gt;&#xA;  Task I: Landing from a No Flap or a Nonstandard Flap Approach  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;VII. Normal and Abnormal Procedures&lt;br&gt;&#xA;  Task A: Normal and Abnormal Procedures  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;VIII. Emergency Procedures&lt;br&gt;&#xA;  Task A: Emergency Procedures  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;IX. Postflight Procedures&lt;br&gt;&#xA;  Task A: After-Landing Procedures&lt;br&gt;&#xA;  Task B: Anchoring (AMES/ASES)&lt;br&gt;&#xA;  Task C: Docking and Mooring (AMES/ASES)&lt;br&gt;&#xA;  Task D: Beaching (AMES/ASES)&lt;br&gt;&#xA;  Task E: Ramping (AMES/ASES)&lt;br&gt;&#xA;  Task F: Parking and Securing &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-06T03:36:19.963" LastActivityDate="2014-02-06T03:36:19.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1576" PostTypeId="2" ParentId="1573" CreationDate="2014-02-06T01:20:08.877" Score="11" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2004/February/9/Pilots-can-request-extensions-to-temporary-certificates-online&quot;&gt;this AOPA article&lt;/a&gt;, you can request an extension online through the FAA's &lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/airmen_services/&quot;&gt;Airmen On-Line Services&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also can look up your current status here: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/new_verification_info/&quot;&gt;http://www.faa.gov/licenses_certificates/airmen_certification/new_verification_info/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my case, this was updated about a week before my card arrived in the mail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see what date's submissions they have processed here: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification&quot;&gt;http://www.faa.gov/licenses_certificates/airmen_certification&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="6" LastEditDate="2014-02-06T18:49:42.083" LastActivityDate="2014-02-06T18:49:42.083" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1577" PostTypeId="1" AcceptedAnswerId="1578" CreationDate="2014-02-06T02:08:46.110" Score="8" ViewCount="3729" Body="&lt;p&gt;I know it might seem like a silly basic question, clearly some of these aircraft are awfully complex.  I doubt anyone questions the idea of a type rating for a 747-400.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But where is the line between, &quot;sure, if you can fly you can probably fly this one&quot; and, &quot;you need to know how to fly this plane in particular&quot;.  What sorts of functionality cause that sort of distinction?  &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="69" LastEditDate="2014-02-17T17:48:01.737" LastActivityDate="2014-02-17T17:48:01.737" Title="Why do some aircraft require type ratings to fly them?" Tags="&lt;aircraft-certification&gt;&lt;pilot-technique&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1578" PostTypeId="2" ParentId="1577" CreationDate="2014-02-06T02:17:39.523" Score="2" Body="&lt;p&gt;The FAA specifies the airplanes that require a type rating in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/daa4c54debeb6dca86256f3400626ab0/15c90b07303160f48625793b0068f317!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.31&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 61.31 - Type rating requirements, additional training, and&#xA;  authorization requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Type ratings required. A person who acts as a pilot in command of&#xA;  any of the following aircraft must hold a type rating for that aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Large aircraft (except lighter-than-air).&lt;br&gt;&#xA;  (2) Turbojet-powered airplanes.&lt;br&gt;&#xA;  (3) Other aircraft specified by the Administrator through aircraft type certificate procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So in short, large aircraft (meaning that they weigh more than 12,500 lbs.), aircraft having turbojet engines, or any airplane deemed suitable complex that it needs it by the FAA need a type rating in order to fly it as PIC.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-06T02:17:39.523" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="1579" PostTypeId="1" AcceptedAnswerId="1580" CreationDate="2014-02-06T03:49:04.480" Score="10" ViewCount="2808" Body="&lt;p&gt;I believe anything the FAA refers to as a &quot;rating&quot; &lt;em&gt;upgrades&lt;/em&gt; automatically with your license. For example, if I get my instrument rating on my Private Pilot License, I don't have to retake the instrument checkride when I get my commercial license in order to fly IFR commercially. This is not true for license classes (single engine land, multi-engine land, single engine sea, multi-engine sea). If I get a private MEL, and then take my commercial checkride in a single engine, I still have to take another commercial MEL checkride in order to exercise commercial privileges in a multi-engine airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, do type ratings work like instrument ratings or like license classes, and what regulations govern this?&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2015-04-10T10:23:26.137" Title="Does a Type Rating &quot;upgrade&quot; with your license?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1580" PostTypeId="2" ParentId="1579" CreationDate="2014-02-06T04:00:52.473" Score="11" Body="&lt;p&gt;The answer to this lies in &lt;a href=&quot;http://fsims.faa.gov/WDocs/8900.1/V05%20Airman%20Cert/Chapter%2002/05_002_018Rev1.htm&quot;&gt;8900.1, Volume 5, Chapter 2, Section 18 - Conduct an Airline Transport Pilot Certification, Including Additional Category/Class Ratings&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases, yes the type rating &quot;upgrades&quot; or &quot;elevates&quot; along with your license since the type rating is always evaluated at ATP standards, even if you only have a private or commercial certificate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exceptions are type ratings for single-engine airplanes and type ratings that have a &quot;VFR ONLY&quot; restriction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;8900.1 excerpt:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-710    PILOT CERTIFICATE LEVEL AND CATEGORY AND CLASS RATING.&lt;/strong&gt; The following category and class rating(s) for which the applicant has&#xA;  qualified on the original or subsequent ATP practical tests are&#xA;  entered on the ATP certificate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;A.    Addition of Lighter-than-Air and Glider Class Ratings.&lt;/strong&gt; A lighter-than-air or glider category rating may be added to an existing&#xA;  ATP certificate; however, the rating may be added only at the&#xA;  recreational, private, or commercial pilot certificate level, as&#xA;  appropriate to the practical test completed. There is no provision for&#xA;  the original issuance of an ATP certificate with a lighter-than-air or&#xA;  glider category rating.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;B.    Type Ratings.&lt;/strong&gt; Type rating tests are conducted to the ATP standard for all grades of pilot certificate. Therefore, all type&#xA;  ratings in that category and class of aircraft for which the practical&#xA;  test is conducted in are upgraded after successful completion of the&#xA;  practical test. For example, a person who holds B-737, DC-3, and SK-62&#xA;  type ratings on his or her commercial pilot certificate, and later&#xA;  satisfactorily completes an ATP practical test in a CE-750, would have&#xA;  his/her B-737 and DC-3 type ratings elevated up to the ATP&#xA;  certificate. The SK-62 would not elevate up because the practical test&#xA;  was in a multiengine airplane. However, when the person satisfactorily&#xA;  completes an ATP practical test in a helicopter, the SK-62 would then&#xA;  elevate up to the ATP certificate. Therefore, all of the type ratings&#xA;  held on the superseded certificate carry forward at the new&#xA;  certificate level within category and class.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE:  A type rating for a single-engine airplane may not be upgraded&#xA;  to the ATP level.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1)    Except for type ratings and, under some circumstances, the&#xA;  instrument rating, other ratings indicated on the superseded pilot&#xA;  certificate are carried forward at the commercial, private, or&#xA;  recreational pilot certificate level, as indicated on the superseded&#xA;  certificate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2)    Instrument rating privileges are shown on the ATP certificate&#xA;  only if the ATP practical test was conducted under visual flight rules&#xA;  (VFR) only, or to retain instrument privileges that were held on the&#xA;  superseded certificate for a category of aircraft other than the one&#xA;  used for the ATP practical test.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;C.    Type Rating Limited to VFR.&lt;/strong&gt; A type rating bearing the limitation “VFR ONLY” may be added to an existing certificate other&#xA;  than an ATP certificate under the provisions of § 61.63(e). This&#xA;  limitation may be added to an aircraft type rating not capable of&#xA;  instrument maneuvers or procedures required on a practical test. The&#xA;  practical test must be administered under the appropriate ATP PTS for&#xA;  an aircraft type rating limited to “VFR ONLY”. A type rating bearing&#xA;  the limitation “VFR ONLY” may be added to an existing ATP certificate&#xA;  under the provisions of § 61.157(g). The practical test must be&#xA;  administered under the appropriate ATP PTS for an aircraft type rating&#xA;  limited to “VFR ONLY.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE:  There is no provision for taking an initial practical test for&#xA;  an ATP certificate in an aircraft that would require a VFR limitation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-06T05:19:38.477" LastActivityDate="2014-02-06T05:19:38.477" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1581" PostTypeId="2" ParentId="1573" CreationDate="2014-02-06T04:01:05.777" Score="8" Body="&lt;p&gt;&lt;strong&gt;The FSDO can issue you a new temporary certificate&lt;/strong&gt; if your previous one has or is about to expire and your permanent one hasn't arrived in the mail yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I got my ATP, I had to file on paper rather than through IACRA and my certificate was delayed long enough that I needed to ask an inspector to write me out a new temporary.  Took about ten minutes start to finish, the hardest part was the drive to the FSDO.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-02-06T04:01:05.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1582" PostTypeId="1" AcceptedAnswerId="1590" CreationDate="2014-02-06T09:05:45.983" Score="12" ViewCount="5923" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What difference to the pilot does it make it say a runway is Concrete or Asphalt? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does it require different information in the flight management system or other calculations? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-06T15:50:47.170" LastActivityDate="2019-03-18T18:53:44.540" Title="What difference does the choice of paved runway surface make to aircraft?" Tags="&lt;airport&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1583" PostTypeId="1" AcceptedAnswerId="1584" CreationDate="2014-02-06T14:30:16.793" Score="30" ViewCount="15630" Body="&lt;p&gt;I understand that most larger jets have a &lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot;&gt;Ram Air Turbine (RAT)&lt;/a&gt; in case of total electrical failure (for instance, when you &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;run out of fuel&lt;/a&gt;) in order to at least have some hydraulics and a couple of instruments. The RAT gets deployed automatically at the loss of electrical systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But how does it get deployed? I'm interested in the triggering mechanism, as, during a complete electrical failure, there can be no electrical trigger (computer or otherwise). So it must be something mechanical. Or are they relying on batteries?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I figured it'd have to be some failsafe mechanism, like stored (hydraulic or otherwise) pressure held back by something like an electromagnet or hydraulic pressure, cut the power and presto, the RAT deploys. However, I've never seen one deployed on an aircraft sitting on the ground with the power off, so that kind of shot down that idea.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="64" LastEditDate="2014-02-08T05:21:04.407" LastActivityDate="2018-09-05T02:53:19.273" Title="How do Ram Air Turbines get deployed?" Tags="&lt;safety&gt;&lt;aircraft-failure&gt;&lt;aircraft-systems&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1584" PostTypeId="2" ParentId="1583" CreationDate="2014-02-06T15:54:36.480" Score="27" Body="&lt;p&gt;The RAT is automatically deployed on many aircraft, including the CRJ and A320 series, but it can be manually released as well. In between the loss of power and the RAT spins up you have the batteries to fall back to which are normally fully charged.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;strong&gt;Airbus Manual&lt;/strong&gt; has the following comment on the APU:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In case of total loss of all main generators, the RAT is automatically&#xA;extended and drives the emergency generator via a hydraulic motor. The&#xA;EMER GEN supplies the AC ESS BUS and the DC ESS BUS via the ESS TR.&#xA;The ECAM WD remains powered, with associated procedures presented.&#xA;Alternate law is operative through ELAC 1 and SEC 1&lt;/p&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=A319-320-321_Flight_Deck_and_Systems_Briefing_for_Pilots.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;While this is for the &lt;strong&gt;CRJ&lt;/strong&gt;, who call it an Air Driven Generator (ADG):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In the event of a complete AC power failure in flight, the ADG will&#xA;automatically deploy and supply emergency AC power to the ADG bus and&#xA;to the AC essential bus. If the automatic deploy function fails, the&#xA;ADG can be deployed manually by pulling the ADG manual release handle&#xA;on the ADG CONTROL control panel at the rear of the center console.&lt;/p&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=CRJ-00_and_00-Electrical.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A RAT, with the spring loaded actuator visible:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z8vP6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z8vP6.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;I think most if not all are spring loaded, and have a little help from gravity on the way. You'll also notice that many are stored to be pushed into place by the jetstream.&lt;/p&gt;&#xA;&lt;p&gt;Have a look at this &lt;a href=&quot;http://www.youtube.com/watch?v=67pBrUVPAO8&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt; below around 0:20. The slow upwards motion suggests that it's having to reload the spring energy at 1:20. The doors are attached mechanically.&lt;/p&gt;&#xA;&lt;p&gt;Taking a look at the &lt;strong&gt;Airbus Electrical System&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AZlRM.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AZlRM.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As can be seen, there's a hierarchy to electrical power use, and the battery feeds the essential busses, where the RAT deployment would be included. If I'm not mistaken, power is very limited: You loose some of the more fancy control computers along with the non-necessary stuff, like the copilot's displays, as can be seen in the following &lt;a href=&quot;http://www.youtube.com/watch?v=djd7f_azfiI&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Bear in mind that some aircraft, such as the 747 (up to -400), do not have a RAT on the aircraft, and rely on the windmilling engines to provide sufficient hydraulics to control the aircraft, and as such there's no deployment of sorts necessary.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-09-05T02:53:19.273" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="1585" PostTypeId="5" CreationDate="2014-02-06T15:59:39.647" Score="0" Body="&lt;p&gt;&lt;strong&gt;Aircraft systems&lt;/strong&gt; are the essential systems found on most aircraft, including power plants, fuel systems, electrical systems, and flight instruments.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="12623" LastEditDate="2016-06-27T03:51:10.413" LastActivityDate="2016-06-27T03:51:10.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1586" PostTypeId="4" CreationDate="2014-02-06T15:59:39.647" Score="0" Body="The essential systems found on most aircraft, including power plants, fuel systems, electrical systems, and flight instruments." OwnerUserId="38272" LastEditorUserId="38272" LastEditDate="2019-03-28T18:21:59.647" LastActivityDate="2019-03-28T18:21:59.647" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1587" PostTypeId="1" AcceptedAnswerId="1588" CreationDate="2014-02-06T16:47:21.507" Score="12" ViewCount="3427" Body="&lt;p&gt;I remember reading that the security for foreigners doing a flying license in the United States were rigorous (as would be expected). As a European Union citizen, what would I expect to need to do from a paperwork/legal standpoint (FAA, CBP etc.) to be allowed to pursue a private licence in the USA, assuming I have no previous flying experience?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-02-06T22:13:17.240" LastActivityDate="2014-02-07T01:47:59.453" Title="What security clearances does a foreign citizen doing a flying course in the United States have to pass?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;usa&gt;&lt;student-pilot&gt;&lt;tsa&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1588" PostTypeId="2" ParentId="1587" CreationDate="2014-02-06T17:04:58.040" Score="14" Body="&lt;p&gt;You need 2 things before you can start flight training in the U.S.:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An &lt;strong&gt;appropriate visa&lt;/strong&gt;. &lt;em&gt;A tourist visa (B2), business visa (B1) or VWP (Visa Waiver Program) is &lt;strong&gt;not&lt;/strong&gt; accepted&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;TSA clearance&lt;/strong&gt; through the &lt;a href=&quot;https://www.flightschoolcandidates.gov/&quot;&gt;Alien Flight Student Program (AFSP)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Flight-Instructor-Resources/AOPAs-Guide-to-TSAs-Alien-Flight-Training-Citizenship-Validation-Rule.aspx&quot;&gt;complete process&lt;/a&gt; is documented at the AOPA website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a nutshell, this is what you need to do:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Make sure you have a proper visa or permanent resident card (green card). A visa that allows you to &lt;strong&gt;&lt;em&gt;live&lt;/em&gt;&lt;/strong&gt; in the U.S. is fine (you don't need a specific visa for flight training). Examples of appropriate visas: H1B, H4, L1, L2 but there are many others&lt;/li&gt;&#xA;&lt;li&gt;If you don't have one of the visas mentioned above, you need to apply for a student visa (&lt;strong&gt;M-1&lt;/strong&gt;). You need to contact a flight school that will assist you with the visa application.&lt;/li&gt;&#xA;&lt;li&gt;Contact a flight school if you haven't already done so in the previous step. They will register your &quot;case&quot; and provide you with information you need when applying for TSA clearance.&lt;/li&gt;&#xA;&lt;li&gt;Apply for the AFSP program on the TSA website&lt;/li&gt;&#xA;&lt;li&gt;Wait for approval by the TSA (is a multistep process that could take a while. It includes having your fingerprints scanned, among other things)&lt;/li&gt;&#xA;&lt;li&gt;Start your training&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2014-02-07T01:47:59.453" LastActivityDate="2014-02-07T01:47:59.453" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1589" PostTypeId="2" ParentId="1587" CreationDate="2014-02-06T17:06:01.247" Score="3" Body="&lt;p&gt;There are two different legal requirements for a citizen of a foreign country to do flight training in the United States:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You require an TSA approval for each course you intend to participate in (if you for example also like to do your instrument rating in the US you need a second approval). Read more about TSAs Alien Flight Student Program on their &lt;a href=&quot;https://www.flightschoolcandidates.gov/afsp2/?acct_type=c&amp;amp;section=WN&quot; rel=&quot;nofollow&quot;&gt;website&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You're also required to have a visa to legally stay in the United States for the time of your training. Most probably you'll require a student visa (M1) but maybe also another type of visa is appropriate for you. Find more information on the website of the US embassy in your country. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When choosing your flight school do not only consider getting the TSA approval but also if your flying hours there will be accepted by EASA to get your desired license. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-02-06T17:47:02.197" LastActivityDate="2014-02-06T17:47:02.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1590" PostTypeId="2" ParentId="1582" CreationDate="2014-02-06T17:27:08.793" Score="6" Body="&lt;p&gt;Both are paved surfaces, so it doesn't make any difference when calculating takeoff and landing distances (ASDR, TORR, TODR, LDR). If your aircrafts performance computer offers the possibility to calculate the takeoff and landing performance, speeds and distances it won't make any difference between concrete and asphalt runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also from the pilots perspective, not thinking about the calculations, it is not a real difference. Maybe asphalt runways are a little more prone to have standing water on it if they are not groved then concrete runways and also tend more to get cracks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports will have their reasons why they decide for one of these types of runway. The condition of the surface the runway is build on (slopes, strength, water) as well as the costs will obviously be factors which needs to be considered. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-02-06T17:39:43.710" LastActivityDate="2014-02-06T17:39:43.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1591" PostTypeId="2" ParentId="1582" CreationDate="2014-02-06T17:57:43.633" Score="8" Body="&lt;p&gt;Concrete is better for certain large airports. Asphalt never completely hardens, and will always behave like an extremely viscous liquid. So when you heat it up (on a hot summer's day), it becomes less viscous. When you put a heavy weight on it (like an airliner), it will tend to flow away from and surround that airliner. Planes pull up to a gate, sit for an hour or so, and suddenly their wheels have sank into the ramp six inches and they can't move. Same with runways, the constant shock of landing aircraft cause the asphalt to buckle and warp eventually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concrete has issues in the cold, however, especially if it is not laid well. It can buckle and crumble when it expands and contracts. However, it only gets stronger as it ages and it can easily be made to withstand the hardest of landing impacts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The type of material does not make any noticeable difference to takeoff/landing performance.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-06T17:57:43.633" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1592" PostTypeId="2" ParentId="1571" CreationDate="2014-02-06T18:03:22.693" Score="12" Body="&lt;p&gt;Well how many people get airsick during each flight and how many of those really vomit? And of those, how many actually use the provided sick bags? I'm not familiar with getting air sick but I'm sure there are not a lot people really using these bags. There is also no legal requirement for having sick bags. It is an item for 'additional passenger comfort'. Ryanair probably thought this way and so they saved some more money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also don't hand out sick bags when they are encountering chops but I'm sure they will have one for you if you ask them.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="97" LastEditDate="2014-02-07T13:47:03.377" LastActivityDate="2014-02-07T13:47:03.377" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1593" PostTypeId="1" AcceptedAnswerId="1594" CreationDate="2014-02-06T19:49:54.083" Score="11" ViewCount="3788" Body="&lt;p&gt;The 8900 is sometimes quoted as a reference when trying to determine FAA policies.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is it and where can it be found?  Is it regulatory in nature?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2020-01-30T12:45:43.123" Title="What is the &quot;8900&quot; that the FAA uses for guidance?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1594" PostTypeId="2" ParentId="1593" CreationDate="2014-02-07T02:14:58.380" Score="14" Body="&lt;p&gt;The &lt;strong&gt;Flight Standards Information Management System&lt;/strong&gt;, created by &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8900.1.pdf&quot;&gt;FAA Order 8900.1&lt;/a&gt;, is the source of all information relating to aviation safety inspector job tasks.  It's about 8,000 pages worth of (non-regulatory) guidance and policy helping FAA Inspectors to do their job properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's an electronic-only document, which can be found at &lt;a href=&quot;http://fsims.faa.gov/&quot;&gt;fsims.faa.gov&lt;/a&gt;, or by visiting the &lt;a href=&quot;https://www.faa.gov/&quot;&gt;FAA homepage&lt;/a&gt; and entering &quot;8900&quot; in the search box at the top right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's all kinds of good stuff in there, such as:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.5,Ch2,Sec12&quot;&gt;How do I give a practical test for a CFI applicant with a sport pilot rating?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.4,Ch9,Sec1&quot;&gt;How do I perform field approval of a major repair or alteration?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.6,Ch1,Sec4&quot;&gt;How do I do a ramp inspection?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;And lots more!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FSIMS is open to the general public - if you want to know what an inspector does day in and day out (or what to expect when you meet one), FSIMS is the one-stop-shopping location for the answers to all your questions.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-02-07T02:42:39.207" LastActivityDate="2014-02-07T02:42:39.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1595" PostTypeId="5" CreationDate="2014-02-07T02:15:34.160" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;https://www.tsa.gov/&quot; rel=&quot;nofollow&quot;&gt;Transportation Security Administration&lt;/a&gt; (TSA) is part of the US &lt;a href=&quot;https://www.dhs.gov/&quot; rel=&quot;nofollow&quot;&gt;Department of Homeland Security&lt;/a&gt; and is responsible for securing and protecting all major US transportation systems, including aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TSA directly controls or influences many aspects of aviation security, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Security standards and procedures on the ground and in the air&lt;/li&gt;&#xA;&lt;li&gt;Security screening of pilots&lt;/li&gt;&#xA;&lt;li&gt;Security screening of passengers&lt;/li&gt;&#xA;&lt;li&gt;Searching cargo&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that the TSA is concerned with &lt;em&gt;security&lt;/em&gt;, not &lt;em&gt;safety&lt;/em&gt;, which is the responsibility of the &lt;a href=&quot;http://www.ntsb.gov/Pages/default.aspx&quot; rel=&quot;nofollow&quot;&gt;National Transportation Safety Board (NTSB)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about TSA requirements for pilots and aircraft, including student pilot screening and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Alien_Flight_Student_Program&quot; rel=&quot;nofollow&quot;&gt;Alien Flight Student Program (AFSP)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions about passenger security checkpoints and baggage searches are off-topic on this site; you can ask them on &lt;a href=&quot;http://travel.stackexchange.com/&quot;&gt;travel.SE&lt;/a&gt; instead.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="62" LastEditDate="2016-05-24T20:58:05.230" LastActivityDate="2016-05-24T20:58:05.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1596" PostTypeId="4" CreationDate="2014-02-07T02:15:34.160" Score="0" Body="The Transportation Security Administration is responsible for aviation security in the USA, including screening pilots and passengers" OwnerUserId="4" LastEditorUserId="62" LastEditDate="2016-05-24T20:58:05.230" LastActivityDate="2016-05-24T20:58:05.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1597" PostTypeId="2" ParentId="1562" CreationDate="2014-02-07T02:23:43.870" Score="11" Body="&lt;p&gt;I'm a little late to this question, but want to add a little for people who aren't familiar with an aircraft heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you said, the dialog is intentionally silly (and not entirely accurate) but most of what they are saying is loosely based on reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short version is that a vector is where an air traffic controller is talking to an aircraft that is visible on radar, they know where they want the aircraft to go, and they assign a direction for them to fly in order to get there.  This gets the aircraft where they want them without the aircraft needing to navigate on their own, and often allows them to take a &quot;shortcut&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The longer version:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;vector&lt;/em&gt; as defined in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/index.htm&quot; rel=&quot;noreferrer&quot;&gt;Pilot Controller Glossary is&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/V.HTM&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;VECTOR&lt;/strong&gt;&lt;/a&gt; - A heading issued to an aircraft to provide&#xA;  navigational guidance by radar.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(See ICAO term RADAR VECTORING.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course, that leads to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/R.HTM&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;RADAR VECTORING [ICAO]&lt;/strong&gt;&lt;/a&gt; - Provision of navigational guidance&#xA;  to aircraft in the form of specific headings, based on the use of&#xA;  radar.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which then leads to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/H.HTM&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;HEADING&lt;/strong&gt;&lt;/a&gt; - ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wait a minute...  They don't define it!  Okay, for those people that aren't pilots, a heading is the direction that an aircraft is flying.  They are three digit numbers corresponding to the 360 degrees in a circle wrapped around a compass rose:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://academic.brooklyn.cuny.edu/geology/leveson/core/graphics/mapgraphics/circ-360newsx.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0ywYOm.gif&quot; alt=&quot;Compass Rose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While technically a heading is to the nearest degree, ATC will only ever assign headings rounded to the nearest 5 degrees.  So, after North, the usable headings would be: 005, 010, 015, 020, etc. all the way around until you get to 355 and then 360.  After that it wraps around again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if air traffic control wants you to fly North East, they will tell you to fly a heading of 045, South would be 180, and North would be 360 (fun fact, 000 is not a valid heading).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When ATC assigns a heading for a vector, they always have to be cognizant of what happens if the radio in the aircraft fails.  Obviously they wouldn't expect you to fly straight ahead in that direction forever, so they include the end result of the vector in the clearance.  Usually they also include the direction of the turn for those pilots that aren't very good determining directions.  ;-)  For example, they could say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, Turn left, fly heading 345, radar vectors to Fort Lauderdale International Airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case, they expect the aircraft to start a left turn, roll out on a heading of 345 and continue to fly straight until they get another clearance.  If the radio failed, they would turn direct to the airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes they want the aircraft to fly a heading until they intercept a published portion of an instrument procedure.  In this case, they would say something like:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, fly heading 045 to intercept &amp;lt;the procedure&amp;gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The airplane would then fly the assigned heading until they get to the procedure and then fly the published procedure!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-08T16:28:21.333" LastActivityDate="2014-02-08T16:28:21.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1598" PostTypeId="1" AcceptedAnswerId="1600" CreationDate="2014-02-07T02:34:23.603" Score="11" ViewCount="1981" Body="&lt;p&gt;Why would ATC generally issue vectors instead of simply issuing speed reductions to aircraft? It'd seem more efficient to have aircraft flying less track miles, so is there any reason that speed control is worse than giving vectors to aircraft?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-02-07T02:54:24.220" Title="Why are vectors used for sequencing rather than speed control?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1599" PostTypeId="2" ParentId="1598" CreationDate="2014-02-07T02:52:21.380" Score="8" Body="&lt;p&gt;It is easier for an aircraft to change headings than to change speed, especially in situations that would require the aircraft to slow down and then speed back up repeatedly.  ATC is also restricted from slowing aircraft below certain minimum speeds until they get closer to the airport, so a vector may be their only option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if ATC is trying to line two airplanes up on final and get them spaced a certain distance apart and going the same speed, a vector is usually the best tool because all they have to do is angle the following airplane correctly to intercept final and don't have to issue any speed adjustments.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-07T02:52:21.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1600" PostTypeId="2" ParentId="1598" CreationDate="2014-02-07T02:54:24.220" Score="11" Body="&lt;p&gt;Let's say you have two aircraft that will reach the same point in space at the same time, and your job is to keep them three miles apart.  One way to do it is to calculate how many knots the second aircraft should reduce their speed so that at the time the first aircraft reaches the point, the second aircraft will have fallen three miles in trail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately for you, this means that you have to work a time-speed-distance-wind problem for every single aircraft that you, as a controller, handle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, you pick a point three miles away and tell the second aircraft to fly there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air traffic controllers are human, and humans are better at angles than we are at numbers.  The simplest thing for controllers is usually the best thing - they've got lots on their mind already without making them do math too!  This might change in the NEXTGEN air traffic network (where everyone has a GPS position and speed readout right there on the screen) but for now, easy is better than hard.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-02-07T02:54:24.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1601" PostTypeId="1" AcceptedAnswerId="25271" CreationDate="2014-02-07T03:13:41.627" Score="12" ViewCount="7949" Body="&lt;p&gt;Most 135 training/testing says something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f6c71bcc2c3d80b2d3a3c07b9e53b274&amp;amp;node=14:3.0.1.1.11.8.3.16&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;§135.343&lt;/a&gt;   Crewmember initial and recurrent training requirements. No&#xA;  certificate holder may use a person, nor may any person serve, as a&#xA;  crewmember in operations under this part &lt;strong&gt;&lt;em&gt;unless that crewmember has&#xA;  completed the appropriate initial or recurrent training phase of the&#xA;  training program appropriate to the type of operation in which the&#xA;  crewmember is to serve since the beginning of the 12th calendar month&#xA;  before that service&lt;/em&gt;&lt;/strong&gt;. This section does not apply to a certificate&#xA;  holder that uses only one pilot in the certificate holder's&#xA;  operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Before that though, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f6c71bcc2c3d80b2d3a3c07b9e53b274&amp;amp;node=14:3.0.1.1.11.8.3.2&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 135.323&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f6c71bcc2c3d80b2d3a3c07b9e53b274&amp;amp;node=14:3.0.1.1.11.8.3.2&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;§135.323&lt;/a&gt; - Training program: General.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Whenever a crewmember who is required to take recurrent training&#xA;  under this subpart completes the training in the calendar month&#xA;  before, or the calendar month after, the month in which that training&#xA;  is required, the crewmember is considered to have completed it in the&#xA;  calendar month in which it was required.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So let's say that I completed initial training in March.  This says that if I complete recurrent training in February or April that they consider the training to have been completed in March.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what happens if a year passes and recurrent training is due.  I don't make it in February or March, but the company schedules me for recurrent training towards the end of April.  Is it legal for me to fly in April before I go to recurrent training?  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;At this point, I don't meet 135.343 (because I am no longer within the required 12 calendar months) but I haven't been to training yet, so 135.323 doesn't really apply.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my interpretation of the regulations I would say no, &lt;strong&gt;however&lt;/strong&gt; every 135 company that I have ever flown for continues using pilots until they go to school, or stop flying at the end of the late grace month if they still haven't gone.  The POI's have never complained about it.  I feel like I must be missing something.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it legal for me to fly 135 trips during the late-grace month??  Note that the same the same scenario applies to 61.58 PIC checks as well, which also have a provision to train during the eligibility period (the month before or the month after it is due).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-02-15T21:01:24.570" LastActivityDate="2017-05-02T19:33:23.697" Title="For training with a grace month, is it legal to fly in the month after training expires before going to school?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;far-91&gt;&lt;far-61&gt;&lt;far-135&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1603" PostTypeId="1" AcceptedAnswerId="1604" CreationDate="2014-02-07T08:03:31.353" Score="14" ViewCount="3211" Body="&lt;p&gt;Antennas sticking out of an aircraft obviously increase profile drag, but the folks who design antennas have done a lot to improve aerodynamics: High performance aircraft can have antennas mounted inside of fiberglass components like wingtips, and flush-mounte antennas are available for transponders and DME equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For slower light GA aircraft more aerodynamic antennas are also available (e.g. &lt;a href=&quot;http://www.rami.com/product-view.php?pid=24&quot;&gt;blade-style transponder antennas&lt;/a&gt; are available which produce about 80% less drag than older &lt;a href=&quot;http://www.rami.com/product-view.php?pid=164&quot;&gt;spike-and-ball style antennas&lt;/a&gt;), measured at 250 MPH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the average light GA aircraft has a V&lt;sub&gt;NE&lt;/sub&gt; below 250 MPH and isn't generally covered in antennas, how significant is the antenna drag on a typical light GA airframe?  For example, would stripping the ~6 pounds of antenna drag from your average Cessna make an appreciable difference in airspeed?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-04T11:19:36.170" Title="How significant is antenna drag on light GA aircraft?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1604" PostTypeId="2" ParentId="1603" CreationDate="2014-02-07T08:59:32.273" Score="16" Body="&lt;p&gt;From an aerospace engineering perspective:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/shaped.html&quot; rel=&quot;noreferrer&quot;&gt;drag coefficient&lt;/a&gt; ($C_D$) of a round antenna is can be estimated by around $.5$ depending on shape, while for an streamlined shape it's around $0.045$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eqqgp.png&quot; alt=&quot;Drag&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://en.wikipedia.org/wiki/Drag_coefficient&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag is defined as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$D=\frac12C_D{\rho}V^2A$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, say you have a 0.01 m wide antenna 0.25 m long, for an aircraft moving at 50 m/s. At sea level conditions, air density $\rho=1.225 \mathrm {kg/m^3}$. Say that $C_D=0.5$. If my calculations add up, it's around $1.9 \mathrm{N}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say you have the same antenna, for the same aircraft aircraft moving at 50 m/s. Air density is $1.225 \mathrm{kg/m^3}$, but this time the antenna is streamlined with $C_D=0.04$. This results in a force of only $0.15 \mathrm {N}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;strong&gt;Updates&lt;/strong&gt;: Originally the formula included $\frac12$ twice which was wrong, and that the force was given in kg, rather than newtons; my apologies.)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-09-04T11:19:36.170" LastActivityDate="2015-09-04T11:19:36.170" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1605" PostTypeId="2" ParentId="1603" CreationDate="2014-02-07T09:05:46.677" Score="5" Body="&lt;p&gt;Given how abysmal your average GA plane is in the aerodynamics department, the amount of drag added by antennas is almost nothing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have some numbers for a Cherokee 160 from an aircraft performance class -although I make no claims that they're 100% accurate- and I'm seeing between 250-360 lbs of drag during level flight depending on the airspeed. Add your 6lbs of antenna drag onto that, and in order to maintain the same airspeed you need at maximum (a density altitude of 10,000 feet) 3 additional horsepower. At sea level it barely registers a change at all.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-07T09:05:46.677" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1606" PostTypeId="1" CreationDate="2014-02-07T15:54:34.807" Score="15" ViewCount="1852" Body="&lt;p&gt;I don't know if this also applies to the U.S. or just to Europe, but in Europe the civilian airspace is frequently used by military jets. On numerous occasions I've seen F-16's and other fighter jets using the same airspace I was flying in (both controlled and uncontrolled)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the regulations, we should &quot;see and avoid&quot; other traffic but &lt;strong&gt;does that rule apply when encountering these fast military jets&lt;/strong&gt;? Let's face it: there's no way you can see and avoid a fighter jet approaching at +400kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there specific regulations covering this? Who's at fault when a midair collision occurs? (sadly it has happened in the past)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It happened again last week: &lt;a href=&quot;https://en.wikipedia.org/wiki/2015_Moncks_Corner_mid-air_collision&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/2015_Moncks_Corner_mid-air_collision&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can something like this happen? Don't F16's have their own radar?&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="4" LastEditDate="2015-07-11T16:09:24.083" LastActivityDate="2015-07-11T16:09:24.083" Title="Are civilian/GA pilots expected to &quot;see and avoid&quot; fast military jets in VMC?" Tags="&lt;airspace&gt;&lt;military&gt;&lt;see-and-avoid&gt;&lt;vmc&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1607" PostTypeId="2" ParentId="1606" CreationDate="2014-02-07T16:00:19.910" Score="8" Body="&lt;p&gt;Yes, both pilots are required to see and avoid at all times when operating in VMC conditions.  Typically the military pilots have radar used to pickup other aircraft that can help them, but ultimately it still comes down to looking outside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have military training routes charted here in the US that are used by military aircraft when operating at high speeds, and pilot should be especially vigilant when operating in the vicinity of one of these routes.  Use all available information: Get flight following and  contact the frequency on the chart for current operational information, and above all keep an eye out for them!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://aeronav.faa.gov/content/aeronav/online/pdf_files/Chart_Users_Guide_11thEd.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Chart Users Guide&lt;/a&gt; shows an example of how they chart it on VFR Charts:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Military Training Routes (MTRs) are shown on  Sectionals and TACs.&#xA;  They are identified by the route  designator: &lt;img src=&quot;https://i.stack.imgur.com/44Wtc.png&quot; alt=&quot;MTR example&quot;&gt;. Route&#xA;  designators  are shown in solid black on the route centerline, &#xA;  positioned along the route for continuity. The designator  IR or VR is&#xA;  not repeated when two or more routes  are established over the same&#xA;  airspace, e.g., IR201- 205-227. Routes numbered 001 to 099 are shown&#xA;  as  IR1 or VR99, eliminating the initial zeros. Direction of  flight&#xA;  along the route is indicated by small arrowheads  adjacent to and in&#xA;  conjunction with each route  designator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The following note appears on Sectionals and TACs  covering the&#xA;  conterminous United States.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NNnfm.png&quot; alt=&quot;MTR Warning&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There are IFR (IR) and VFR (VR) routes as follows:  Route&#xA;  identification: a. Routes at or below 1500’ AGL (with no segment &#xA;  above 1500’) are identified by four-digit numbers;  e.g., VR1007, etc.&#xA;  These routes are generally  developed for flight under Visual Flight&#xA;  Rules. b. Routes above 1500’ AGL (some segments of  these routes may&#xA;  be below 1500’) are identified by  three or fewer digit numbers; e.g.,&#xA;  IR21, VR302,  etc. These routes are developed for flight under &#xA;  Instrument Flight Rules. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MTRs can vary in width from 4 to 16 miles. Detailed  route width&#xA;  information is available in the Flight  Information Publication (FLIP)&#xA;  AP/1B (a DoD  publication), or in the Digital Aeronautical Chart &#xA;  Supplement (DACS) produced by AeroNav Products. Special Military&#xA;  Activity areas are indicated on the  Sectionals by a boxed note in&#xA;  black type. The note  contains radio frequency information for&#xA;  obtaining area  activity status.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xXOPv.png&quot; alt=&quot;MTR Frequency Box&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On IFR charts, they are similar:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MILITARY TRAINING ROUTES (MTRs)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Military Training Routes (MTRs) are routes established  for the&#xA;  conduct of low-altitude, high-speed military flight  training&#xA;  (generally below 10,000 feet MSL at airspeeds  in excess of 250 knots&#xA;  Indicated Air Speed). These  routes are depicted in brown on Enroute&#xA;  Low Altitude  Charts, and are not shown on inset charts or on IFR &#xA;  Enroute High Altitude Charts. Enroute Low Altitude  Charts depict all&#xA;  IR (IFR Military Training Route) and VR  (VFR Military Training Route)&#xA;  routes, except those VRs  that are entirely at or below 1,500 feet&#xA;  AGL. Military Training Routes are identified by designators  (IR-107,&#xA;  VR-134) which are shown in brown on the  route centerline. Arrows are&#xA;  shown to indicate the  direction of flight along the route. The width&#xA;  of the route  determines the width of the line that is plotted on the &#xA;  chart:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Route segments with a width of 5 NM or less, both  sides of the&#xA;  centerline, are shown by a .02” line.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Route segments with a width greater than 5 NM, either  or both sides&#xA;  of the centerline, are shown by a .035”  line.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MTRs for particular chart pairs (ex. L1/2, etc.) are  alphabetically,&#xA;  then numerically tabulated. The  tabulation includes MTR type and&#xA;  unique ident and  altitude range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as who is at fault, it is a joint responsibility so everybody would be in most cases.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-08T03:22:47.227" LastActivityDate="2014-02-08T03:22:47.227" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1608" PostTypeId="2" ParentId="1606" CreationDate="2014-02-07T16:21:16.527" Score="14" Body="&lt;p&gt;It is both parties responsibility to see-and-avoid, but it does help to know where you are more likely to find high speed military activity and high performance maneuvering to aid you in seeing and avoiding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military operations in the US are typically confined to military training routes (MTR), military operations areas (MOA), restricted airspace and prohibited airspace.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MTRs are low altitude, high speed routes and are charted on sectional charts so you know to be extra vigilant around them or to just avoid them altogether. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military operation areas or MOAs are charted and are big boxes with ceiling and floor altitudes.  GA aircraft can query ATC if these are active and in any case they can fly into them.  If a GA aircraft penetrates and active MOA, the military activity is typically stopped until you leave.  General rule of thumb is to just not go there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Restricted areas are only accessible to you when cold, so there will not be military activity there if you allowed to be there.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prohibited airspace may not have military activity before you show up, but certainly will after you do, and you might get to watch an F16 attempt slow flight and form up on your wing.  Remember your intercept procedures for this one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any military activity outside of this will generally be typical enroute flying at altitude.  You will occasionally hear ATC coordinating mid-air refueling but that won't be something you have to worry about.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-07T16:21:16.527" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1609" PostTypeId="1" AcceptedAnswerId="4983" CreationDate="2014-02-07T19:44:44.187" Score="67" ViewCount="83704" Body="&lt;p&gt;I'm told that this is true, but I can't imagine why.  It seems like the fact that there is less air would make the engines less efficient...  But that probably just shows how little I know about jet engines.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-09-30T17:46:45.913" LastActivityDate="2019-02-17T13:06:18.223" Title="Why do jet engines get better fuel efficiency at high altitudes?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;" AnswerCount="10" CommentCount="3" FavoriteCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="1610" PostTypeId="2" ParentId="1609" CreationDate="2014-02-07T20:23:24.807" Score="30" Body="&lt;p&gt;What matters for a jet engine is the pressure and temperature differentials between the exhaust gas and the ambient atmosphere.  It is the expansion and high kinetic energy of the exhaust gas as it exits the engine that provides the thrust (and noise) of a jet (note this does not take into account the bypass portion of a turbofan).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ambient pressure is atmospheric pressure, which for example at the surface is roughly 1000 hPa and at cruise might be 200 hPa or roughly a fifth of the pressure at the surface.  The temperature at that altitude is also typically around -50 C. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exhaust gas pressure and temperature is controlled by a few things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The compression by the N2 compressor stages -- Increases temperature and pressure&lt;/li&gt;&#xA;&lt;li&gt;The hot section -- Greatly increases temperature and pressure&lt;/li&gt;&#xA;&lt;li&gt;The N1/N2 turbine stages -- slight decrease in temp/pressure (work done on moving the turbines).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As the outside pressure is dropping as we climb, to maintain the same pressure differential in the engine, we need less temperature and pressure in the engine, and one way to do this is to reduce airflow into the engine and fuel added to that air.  The atmosphere takes care of reducing airflow (there is just less of it up at cruise, though this also depends on airspeed) and the FADEC takes care of adjusting the fuel flow.  The net result is less fuel needed to produce the same pressure differential when the air outside has a lower pressure, e.g. cruise flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the other answers/comments make reference to mass flow through the jet, and particularly the mass flow through the exhaust nozzle.  I agree with that, but I didn't mention it directly because that mass flow is setup by the pressure gradient within the engine.  I should also clarify that pressure at the nozzle will be at or very close to ambient atmospheric pressure and it is the pressure gradient between that ambient pressure and that in the hot section that establishes the mass flow rate out of the engine.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, to address the bypass ratio comment, see Lnafziger's comment.  The turbofan engines on the EMB-145 are similar in that the bypass provides more thrust at sea level than cruise.  This perhaps relates to increased fuel efficiency at cruise in that the N1 fan is doing less work and thus the N1 turbine is extracting less energy from the engine.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-13T19:30:26.787" LastActivityDate="2014-02-13T19:30:26.787" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1611" PostTypeId="2" ParentId="1609" CreationDate="2014-02-07T20:24:14.390" Score="21" Body="&lt;p&gt;They work better at high altitude firstly because the air is cooler. Cool air expands more when heated than warm air. It is the expansion of the air that drives combustion engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second reason is the low density of the air. Low density causes low drag and therefore the aircraft flies much faster at high altitude than on low altitude when it is given the same thrust. At this high speed, the mass flow through the engine is comparable to the mass flow at low speed in high density air (low altitude). The amount of energy needed is to heat the air to exhaust temperature is comparable between high and low altitudes. But since the aircraft at high altitude flies much faster, the amount of power generated is higher $(Power=Thrust\times{Speed})$ at altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference with propeller aircraft is that at high speeds the propeller loses efficiency, and therefore the available power decreases with altitude.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="97" LastEditDate="2014-04-18T03:17:29.937" LastActivityDate="2014-04-18T03:17:29.937" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1612" PostTypeId="1" AcceptedAnswerId="1617" CreationDate="2014-02-07T21:50:27.700" Score="11" ViewCount="16630" Body="&lt;p&gt;Do all flights need to have filed flight plans or only ones that fit certain criteria? What are the criteria?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-02-08T15:58:06.557" LastActivityDate="2014-02-08T15:58:06.557" Title="When is a flight plan required?" Tags="&lt;faa-regulations&gt;&lt;flight-planning&gt;&lt;flight-plans&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1613" PostTypeId="1" CreationDate="2014-02-07T22:05:33.567" Score="10" ViewCount="3835" Body="&lt;p&gt;How does a pilot determine the difference between a firm landing, and one that needs to be written up for a hard landing inspection in a Cessna 172S?&lt;/p&gt;&#xA;" OwnerUserId="186" LastEditorUserId="2143" LastEditDate="2015-02-13T00:29:32.640" LastActivityDate="2015-02-13T00:29:32.640" Title="How can I know if a landing exceeds the hard landing threshold for a Cessna 172S?" Tags="&lt;landing&gt;&lt;general-aviation&gt;&lt;cessna-172&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1614" PostTypeId="1" CreationDate="2014-02-07T22:19:52.663" Score="9" ViewCount="3297" Body="&lt;p&gt;I am currently working on the modeling of blade/casing interactions in aircraft engines. The work is carried out in partnership with a company, therefore, there is a limited amount of it that could be published openly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any &lt;strong&gt;OpenSource&lt;/strong&gt; compressor or turbine blade designs available (e.g. NACA airfoil profiles for wings)? Where could I find detailed dimensions and material properties?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea would be to use it for publication purposes, thus displaying relevant characteristics and realistic behaviors, while keeping all the confidential data of the company internally.&lt;/p&gt;&#xA;" OwnerUserId="201" LastEditorUserId="201" LastEditDate="2014-02-10T19:00:52.800" LastActivityDate="2017-11-18T20:55:13.730" Title="Where can I find detailed dimensions of an aircraft engine compressor blade?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;turboprop&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1615" PostTypeId="2" ParentId="1613" CreationDate="2014-02-07T22:27:30.063" Score="9" Body="&lt;p&gt;Was it uncomfortable or did it hurt?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it hurt you, it probably hurt the plane. That 500 pound engine is hanging a foot and a half from the firewall by four bolts. It's not hard to cause some damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, if you think it needs to be checked, just say something to the mechanic. It's not that time consuming, and it's better to be safe than sorry.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-07T22:27:30.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1616" PostTypeId="2" ParentId="1609" CreationDate="2014-02-07T22:31:25.103" Score="11" Body="&lt;p&gt;&lt;strong&gt;For a non-math approach:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's think how a jet engine works and compare low altitude with high altitude flights. The engine takes air from the intake situated at the front. As you are climbing, the air becomes less dense (there is less air mass in a volume) so you need to go a little faster just so that the mass of the air coming in through the intake is the same in a given second. You will actually get the same mass flow of air at high altitudes as you will get at low altitudes, but you are actually travelling faster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you compress that air, remembering that as you are now travelling faster higher up, the ram effect will help you out and compress some of that air for you, just by 'ramming' your engines into it at high speed. As you compress it you pass it to the combustion chamber where it burns. This combustion stage is the same for both high and low altitudes, although the fact that at higher altitudes air is colder actually helps a little bit, as we can burn more fuel without reaching dangerous temperatures, so that's nice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After burning it up, the air is passed through a turbine then expelled out the back. Now here it gets a bit complicated: You see, it is more efficient to accelerate a lot of air (mass) a little bit(small dv), than to accelerate a little bit of air(small mass) to a very fast speed(dv). This means in turn that the faster the airplane moves, the better the jet propulsive efficiency gets. So as you climb, you go faster and the flow gets better efficiency, plus the lower air pressure behind you means there is less of a force pushing against your outflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what do we have in low vs high flight: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same amount of air intake, same amount of combustion, same amount of fuel used, better jet propulsion at higher altitudes and better speed at higher altitudes. You just get more bangs for your bucks at higher altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For a mathematical approach:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=E8VfieYhsjg&quot;&gt;Jet Engine (Gas Turbine) Efficiency&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-02-07T22:31:25.103" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1617" PostTypeId="2" ParentId="1612" CreationDate="2014-02-07T22:38:33.173" Score="12" Body="&lt;p&gt;In the US you need to file a flight plan for the following flights:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;IFR flights&lt;/li&gt;&#xA;&lt;li&gt;Defense VFR Flights, which are required to fly in the ADIZ that is off the coast of the US (an IFR flight plan may also be used).&lt;/li&gt;&#xA;&lt;li&gt;Some TFR's only allow air traffic to fly within their boundaries if they are on an IFR or VFR flight plan.&lt;/li&gt;&#xA;&lt;li&gt;A DC FRZ flight plan is required to fly VFR in the DC FRZ.&lt;/li&gt;&#xA;&lt;li&gt;A DC SFRA flight plan is required to fly VFR in the DC SFRA.&lt;/li&gt;&#xA;&lt;li&gt;When entering or leaving the U.S., an ICAO international flight plan (IFR or VFR).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other than that, no flight plans are required, but are strongly recommended so that search and rescue gets called if you don't show up at your destination on time!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-08T13:40:56.363" LastActivityDate="2014-02-08T13:40:56.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1618" PostTypeId="2" ParentId="1613" CreationDate="2014-02-08T00:23:10.680" Score="5" Body="&lt;p&gt;StallSpin has already mentioned the crucial point. The firewall will be damaged if the nose gear experiences an excessive shock. It can easily be inspected for deformation by removing the upper half of the cowling (looking through the hole for the oil dipstick,  even with a flashlight,  is not sufficient). The main gear is very sturdy and will probably be damaged last. Anyway, I would sugest to have a close look on it and check the overall condition. Also check the position of the tire valves.  They should be at a 90 degree angle to the tire. A hard landing can go together with brake application during touch down which could cause damage to the tires. Last but not least the oleo strut of the nose gear should be inspected. Find the clearance of the oleo strut under normal loads in the POH.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="774" LastEditDate="2014-02-08T02:22:05.457" LastActivityDate="2014-02-08T02:22:05.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1619" PostTypeId="2" ParentId="1613" CreationDate="2014-02-08T03:30:38.010" Score="2" Body="&lt;p&gt;You should refer to the service manual for your specific airplane, but to give an idea,  the &lt;a href=&quot;http://www.micro-tools.net/pdf/Cessna/172_sm_69-76.pdf&quot; rel=&quot;nofollow&quot;&gt;Cessna 172 AND SKYHAWK SERIES 1969 THRU 1976 SERVICE MANUAL&lt;/a&gt; says that you should look for &quot;buckled skin or floorboards, and loose or sheared rivets in the area of the main gear support&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;18-61. REPAIR AFTER HARD LANDING. Buckled  skin or floorboards, and&#xA;  loose or sheared rivets in  the area of the main gear support will&#xA;  give evidence  of damage to the structure from an extremely hard &#xA;  landing. When such evidence is present, the entire  support structure&#xA;  must be examined, and all support  forgings must be checked for&#xA;  cracks, using a dye  penetrant and proper magnification. Bulkheads in &#xA;  the damaged area must be checked for alignment,  and deformation of&#xA;  the bulkhead webs must be determined with the aid of a&#xA;  straightedge. Damaged support structure, buckled floorboards and&#xA;  skins, and  damaged or questionable forgings must be replaced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2015-02-13T00:27:33.070" LastActivityDate="2015-02-13T00:27:33.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1620" PostTypeId="5" CreationDate="2014-02-08T04:57:34.083" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-02-08T04:57:34.083" LastActivityDate="2014-02-08T04:57:34.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1621" PostTypeId="4" CreationDate="2014-02-08T04:57:34.083" Score="0" Body="For questions relating to how the use of procedures affect operations." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-02-08T05:14:37.433" LastActivityDate="2014-02-08T05:14:37.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1622" PostTypeId="1" AcceptedAnswerId="1623" CreationDate="2014-02-08T06:09:04.990" Score="12" ViewCount="18576" Body="&lt;p&gt;I've flown a Piper that has a button labeled &lt;code&gt;CWS&lt;/code&gt; on the yoke, right next to the &quot;Push-To-Talk&quot; button.  I never got a chance to push it though.  What does it do?&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2017-08-25T08:44:45.647" Title="What's a CWS button?" Tags="&lt;flight-controls&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1623" PostTypeId="2" ParentId="1622" CreationDate="2014-02-08T06:48:37.390" Score="15" Body="&lt;p&gt;Sounds like that plane has (or once had) an STEC autopilot installed - &lt;code&gt;CWS&lt;/code&gt; stands for &lt;b&gt;C&lt;/b&gt;ontrol &lt;b&gt;W&lt;/b&gt;heel &lt;b&gt;S&lt;/b&gt;teering - basically it allows you to set a pitch attitude / turn rate using the yoke, which the autopilot will then maintain until instructed to do otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is still installed you also normally use the &lt;code&gt;CWS&lt;/code&gt; mode as part of the preflight routine to get the autopilot to activate so you can make sure you can overpower it (details on the preflight as well as using the &lt;code&gt;CWS&lt;/code&gt; feature can be found in the autopilot manual, which &lt;em&gt;should&lt;/em&gt; be with the POH).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is no longer installed the switch technically should have been removed with the rest of the system and a blanking plate installed in its place.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-08T06:48:37.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1624" PostTypeId="1" AcceptedAnswerId="1625" CreationDate="2014-02-08T16:26:27.780" Score="7" ViewCount="7758" Body="&lt;p&gt;When flying to Teterboro, NJ (KTEB) and cleared via the JAIKE THREE ARRIVAL from Flat Rock (FAK):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/r2sis.jpg&quot; alt=&quot;JAIKE THREE&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does ATC expect when they give a clearance like:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, Descend VIA the JAIKE THREE ARRIVAL&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then, what if they give the next clearance when over JAIKE:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, Descend and maintain 7000&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I believe that there is a difference in ATC procedures over whether or not the crossing restrictions still need to be made between US and Canadian rules, what should be done in both cases?  (And out of curiosity, does ICAO have anything to say about this situation?)&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2014-03-23T14:25:26.893" LastActivityDate="2014-03-23T14:25:26.893" Title="What is a &quot;Descend Via&quot; clearance?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;transport-canada&gt;&lt;sid-star&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1625" PostTypeId="2" ParentId="1624" CreationDate="2014-02-08T17:17:34.637" Score="8" Body="&lt;p&gt;The &quot;DESCEND VIA&quot; clearance is described in FAA order &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;7110.65U (pdf)&lt;/a&gt; Section 4-5-7 paragraph h, which defines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;h. Instructions to vertically navigate on a STAR/RNAV STAR/FMSP with published &gt;restrictions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PHRASEOLOGY-&#xA;  DESCEND VIA (STAR/RNAV STAR/FMSP name and number)&#xA;  TERMINAL: DESCEND VIA (STAR/RNAV STAR/FMSP name and number and runway number).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE-&#xA;  “Descend via the Mudde One Arrival.”&#xA;  “Cross JCT at flight level two four zero, then descend via the Coast Two &gt;Arrival.”&#xA;  TERMINAL: “Descend via the Lendy One Arrival, Runway 22 left.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This instruction authorizes the pilot to navigate the STAR laterally as published and to navigate vertically to meet all published altitude restrictions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Clearance to “descend via” authorizes pilots:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;To vertically and laterally navigate on a STAR/RNAV STAR/FMSP.&lt;/li&gt;&#xA;  &lt;li&gt;When cleared to a waypoint depicted on a STAR/RNAV STAR/FMSP, to descend from a previously assigned altitude at pilot's discretion to the altitude depicted for that waypoint, and once established on the depicted arrival, to navigate laterally and vertically to meet all published restrictions. ATC is responsible for obstacle clearance when issuing a “descend via” clearance from a previously assigned altitude.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though speed restrictions are not specifically addressed in the above paragraph, it does note that you will meet &quot;all published restrictions&quot; to include speed restrictions.  This is supported by a later note:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EXAMPLE-&#xA;  “United 454 descend via the Haris One Arrival, except after Bruno, maintain one zero thousand.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE-&#xA;  The aircraft should track laterally and vertically on the Haris One Arrival &lt;strong&gt;and should descend so as to comply with all speed and altitude restrictions&lt;/strong&gt; until reaching Bruno and then maintain 10,000. Upon reaching 10,000, aircraft should maintain 10,000 until cleared by ATC to continue to descend.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This example and note pertain to modifications to a published altitude, but the note establishes that you comply with all published altitudes and speeds when flying the procedure as published.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2012/InFO12014.pdf&quot;&gt;InFO 12014&lt;/a&gt; explicitly states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Published speed restrictions are always mandatory. Published speed must be complied with regardless of the use of “Climb/Descend Via” clearance. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the example of the JAIKE 3 Arrival, the clearance&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, Descend VIA the JAIKE THREE ARRIVAL&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;will be issued if you are already established on the arrival laterally and authorizes you do follow the published route and altitudes.  Assuming the FAK transition is your cleared route when you receive the descend via clearance, you would fly the lateral route&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FAK QBEES VAALI PALEO PEEDS FUBRR BUZIE SPNCR JAIKE ILENE WACKI REGLE SBJ &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and you would descend at your discretion to be at 13,000 ft at JAIKE, at 13,000 ft at ILENE, at 11,000 ft at WACKI (and at 250 kts) and 7000 ft at REGLE.  You descend to and cross the fixes at these altitudes because you have been authorized to vertically navigate the STAR via the &quot;DESCEND VIA&quot; clearance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: This arrival contains an &quot;EXPECT&quot; altitude and the controller should not issue a DESCEND VIA clearance until you are past this fix unless you gives you specific instructions as in:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 cross PEEDS at FL240 then descend via the JAIKE 3 arrival&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;If the controller at any time issues an instruction e.g.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234, Descend and maintain 7000&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;then:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;In the USA&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;then you would continue to navigate laterally on the STAR but would descend to 7000 ft, disregarding any published altitudes on the STAR.  You are no longer authorized to navigate vertically on the STAR.  If the controller requires you to still cross certain fixes at certain altitudes, they will specify those crossing restrictions in the descent clerance, e.g.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N1234 Cross WACKI at 11000 250 kts then descend and maintain 7000 ft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h3&gt;In Cadanda / ICAO rules&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;you shall continue to meet all published crossing altitudes on your descent to your cleared altitude.  For reference on this difference, see &lt;a href=&quot;http://content.govdelivery.com/attachments/USAFAA/2012/02/14/file_attachments/95497/InFO12003.pdf&quot;&gt;FAA InFO 12003&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-08T17:40:02.510" LastActivityDate="2014-02-08T17:40:02.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1626" PostTypeId="1" AcceptedAnswerId="1643" CreationDate="2014-02-08T18:43:45.830" Score="17" ViewCount="3460" Body="&lt;p&gt;I've noticed that on almost all aircraft (Boeing, Airbus etc.) the nose gear rotates forwards for retraction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gx88V.jpg&quot; alt=&quot;737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, on a some aircraft, in particular a few Russian models, the opposite is used: the nose gear is rotated towards the rear for stowage:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Xsia.jpg&quot; alt=&quot;Tu154&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(this includes the Tu154, Tu134)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any logic behind this decision? I imagined it was better to place it folding forwards, such that the gear was assisted into place by the air, especially for manual free fall. Looking at pictures of the TU-154 with its gear down, there seems to be plenty of space forward.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-02-08T19:45:33.837" LastActivityDate="2017-06-09T17:12:59.050" Title="Why is there a difference between nosegear retraction directions?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1627" PostTypeId="1" AcceptedAnswerId="1628" CreationDate="2014-02-08T19:09:50.307" Score="16" ViewCount="2104" Body="&lt;p&gt;The reason for my arguments here are (assuming that you have sufficient runway distance):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That with less thrust, less force should also be required to hold the aircraft as desired, and possibly the aircraft should be easier to control and fly when the engine fails than if it does so with the thrust set to full blast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine event, such as a bird strike, might (?) be less likely to have catastrophic consequences for e.g. the turbine blades when they are not running at full thrust and their design limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never having actually commanded an aircraft, are any of these ideas correct?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="3386" LastEditDate="2017-11-14T19:44:32.947" LastActivityDate="2017-11-14T19:44:32.947" Title="Is it possible that derated thrust takeoffs are safer than normal takeoffs?" Tags="&lt;takeoff&gt;&lt;throttle&gt;&lt;bird-strike&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1628" PostTypeId="2" ParentId="1627" CreationDate="2014-02-08T20:10:38.220" Score="19" Body="&lt;p&gt;The reasons presented at ground school for the benefits of de-rated thrust takeoffs were twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;less chance of catastrophic engine failure during takeoff&lt;/li&gt;&#xA;&lt;li&gt;less overall wear between overhauls &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is from this standpoint that reduced thrust takeoffs are safer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you point out, these are only authorized when the weights, temperature and runway length allow, but for the EMB-145 virtually every takeoff we did was eligible for reduced thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You point about ease of control with an engine out is countered by engine out procedures which involve setting max thrust on the remaining engine (for two-engine ops).  During takeoff roll in the EMB-145XR, this puts the other engine at 117% power.  With the exception of flying near $V_{MC}$ (for light twins) the extra thrust is a benefit and not a hindrance to control and if this is at or after $V_1$ you'll want the thrust to go flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question about a bird strike is going to go one of two ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;the bird hits the N1 fan and goes through the bypass ducting&lt;/li&gt;&#xA;&lt;li&gt;the bird hits the N1 fan and is ingested into the N2 compressor stages&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In either scenario a reduced thrust vs full thrust takeoff is not going to make a huge difference, but scenario 2 will be far more destructive to the engine than scenario 1.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="97" LastEditDate="2014-04-16T23:56:23.657" LastActivityDate="2014-04-16T23:56:23.657" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1630" PostTypeId="1" AcceptedAnswerId="1647" CreationDate="2014-02-09T02:04:13.403" Score="22" ViewCount="12119" Body="&lt;p&gt;I have heard and read many times that for &quot;heavy aircraft&quot;, they use a standard rate of turn which is 1.5° per second (4 minute turn), but I have never found an official source which addresses this. Although... I'm actually not even sure where the normal 3° per second (2 minute) standard rate turn is defined either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wikipedia entry on &lt;a href=&quot;http://en.wikipedia.org/wiki/ROT_%28aviation%29&quot;&gt;ROT (Aviation)&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Light aircraft are equipped with 2-minute turn indicators while heavy aircraft are equipped with 4-minute turn indicators.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't see why &quot;heavy&quot; would have anything to with turning rate, but airspeed certainly does.&#xA;So, I'm wondering if this is true, or just something they think is true because airplanes often use half-rate turns at airspeeds above 250 knots and bank limiting prevents them from making a standard rate turn at airspeeds above ≈ 200 knots?&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="19" LastEditDate="2016-11-21T10:44:13.693" LastActivityDate="2016-11-21T10:44:13.693" Title="What is the standard rate of turn for heavy aircraft?" Tags="&lt;faa-regulations&gt;&lt;icao-sarps&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1631" PostTypeId="2" ParentId="1630" CreationDate="2014-02-09T03:03:18.110" Score="4" Body="&lt;p&gt;Many airliners, heavy or otherwise, don't even have turn indicators anymore.  Airliners don't worry about rate of turn, they just go to a given bank angle, typically 25-30 degrees, and are done with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it's true that rate of turn doesn't depend on weight, but heavy aircraft usually fly faster, hence having a slower rate of turn.  Pretty much all airliners go too fast to make a 3 minute turn practical unless in the terminal area and slowed down.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-02-09T03:03:18.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1632" PostTypeId="1" CreationDate="2014-02-09T04:53:59.443" Score="12" ViewCount="16919" Body="&lt;p&gt;Are there speeds that cannot be exceeded at certain altitudes?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="72" LastEditDate="2014-02-09T06:00:53.833" LastActivityDate="2018-01-25T14:39:49.890" Title="Are there limits to speeds at certain altitudes?" Tags="&lt;faa-regulations&gt;&lt;airspeed&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1634" PostTypeId="2" ParentId="1632" CreationDate="2014-02-09T05:45:06.810" Score="15" Body="&lt;p&gt;The following maximum speeds apply in the US (A few aren't based on altitude, but I've included them to be more complete):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=cb470249e723d511451e211bdde99d6f&amp;amp;node=14:2.0.1.3.10.9.7.6&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.817&lt;/a&gt;: Mach 1 over land (with a few exceptions that are noted in Appendix B to 91.817)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.117&lt;/a&gt;(a): 250 KIAS below 10,000 ft. MSL&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.117&lt;/a&gt;(b): 200 KIAS below 2,500 ft. within 4NM of the primary airport for Class C and D airspace (unless within Class B airspace)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.117&lt;/a&gt;(c): 200 KIAS under the shelf of Class B airspace&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.117&lt;/a&gt;(c): 200 KIAS in a VFR corridor through Class B airspace&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0503.html#Rn7352webb&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-3-8&lt;/a&gt;(2): Maximum holding speeds:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At or below 6,000 ft. 200 KIAS&lt;/li&gt;&#xA;&lt;li&gt;6,001 to 14,000 ft. 230 KIAS&lt;/li&gt;&#xA;&lt;li&gt;Above 14,000 ft 265 KIAS&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://tfr.faa.gov/save_pages/detail_1_6386.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Some NOTAMs&lt;/a&gt; specify a maximum speed when operating within their limits.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0507.html#qnI37aJACK&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-7-2&lt;/a&gt;: Maximum speed as assigned by ATC&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.117&lt;/a&gt;(d): Any of these speeds may be exceeded if the minimum safe airspeed for the aircraft is higher and you notify ATC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#14:2.0.1.3.10.2.4.1&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.101&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0507.html#qnI37aJACK&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-7-2&lt;/a&gt; NOTE 2 state that none of these apply when more than 12 NM from the coast of the united states.  Because of this, you will often see pilots fly at greater than 250 KIAS when below 10,000 feet and more than 12 NM off-shore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft specific limitations must also be complied with.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2018-01-25T14:39:49.890" LastActivityDate="2018-01-25T14:39:49.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1635" PostTypeId="1" AcceptedAnswerId="1638" CreationDate="2014-02-09T13:19:10.900" Score="7" ViewCount="1622" Body="&lt;p&gt;I found this picture earlier with a &lt;strong&gt;Lufthansa express&lt;/strong&gt; livery:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/92/Lufthansa_Express_Boeing_737-500_KvW.jpg&quot; alt=&quot;737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also appears to have been on a few larger aircraft like the A300:&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/96/Airbus_A300B4-603,_Lufthansa_Express_AN0482471.jpg&quot; alt=&quot;A300&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could somebody enlighten me as to what this operation was or the difference to mainline Lufthansa? I tried to search but couldn't find anything.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.687" LastActivityDate="2014-04-08T20:40:40.503" Title="What was 'Lufthansa Express'?" Tags="&lt;airline-operations&gt;&lt;lufthansa&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1636" PostTypeId="1" AcceptedAnswerId="1637" CreationDate="2014-02-09T14:46:44.587" Score="19" ViewCount="8758" Body="&lt;p&gt;It's apparently legal for pilots to fly over the top of clouds and fly VFR. However, I don't understand how it's possible to do so, especially since there is no visual reference to rely on to ensure that you are heading in the right direction. So, how exactly &lt;em&gt;does&lt;/em&gt; this work, are there any limitations on this and is it possible to be done safely?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="572" LastEditDate="2017-01-18T10:16:04.023" LastActivityDate="2017-01-18T10:16:04.023" Title="How can pilots fly VFR over-the-top in overcast conditions?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1637" PostTypeId="2" ParentId="1636" CreationDate="2014-02-09T15:13:49.017" Score="16" Body="&lt;p&gt;Perhaps the most important rule for a VFR pilot is &quot;see and avoid&quot; -- be able to see any immediate dangers (other aircraft, buildings, ground) and avoid them. When flying above the clouds, you can certainly see other aircraft and avoid them (as long as you're maintaining required cloud clearances), and the same for buildings. You cannot see the ground but on the presumption that your altitude is well above the ground and not significantly changing, this is not a factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you're able to see the horizon, you're unlikely to become disoriented to the point of not actually knowing that the aircraft is or isn't flying straight and level. (Contrast that with flying in the clouds, where it's easy to become spatially disoriented and not be aware that you're starting to dive.) Limitations are basic: it's the PIC's responsibility to follow the regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to heading in the right direction and navigation in general, VFR flight does not mean one cannot rely on radio aids to navigation. VOR and GPS certainly make navigation very possible while on top, but to get to your question of &quot;can it be done safely?&quot; -- I suppose this comes down to a question of how reliable are your electronics and where are the weak spots; is the pilot under flight following or otherwise in contact with ATC, etc. If one were on top and were to lose the electrical system, there's certainly an emergency to be declared. If already in contact with ATC, it's an emergency that can likely be managed with the utmost of safety.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-02-09T15:13:49.017" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1638" PostTypeId="2" ParentId="1635" CreationDate="2014-02-09T15:24:29.513" Score="4" Body="&lt;p&gt;I found this &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/297598/&quot; rel=&quot;nofollow noreferrer&quot;&gt;forum discussion&lt;/a&gt; from a few years ago, which stated:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;LH Express was their brand name for domestic services for some years in the mid 90s. I'm not sure when the LH Express name disappeared, but they definitely were not promoting the Express name in 1997 any more. So the aircraft you saw was probably just not repainted yet. LH used to operate B737 of various series and several Airbuses.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;One of the guys went on to say it was a low-cost domestic route, set up in competition to &lt;a href=&quot;http://en.wikipedia.org/wiki/DBA_%28airline%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Deutsche BA&lt;/a&gt;. Unfortunately, it did not succeed enough in competition and was eventually shut down. They did fly some small Boeings like the 737, and the Airbus 300 and 310.&lt;/p&gt;&#xA;&lt;p&gt;Additionally, a &lt;a href=&quot;http://www.nytimes.com/1992/10/24/business/worldbusiness/24iht-luft_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;NY Times article&lt;/a&gt; from 1992 gives a small blurb about the startup of the line:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Under the new strategy, eight key domestic German routes are to be served by a special spin-off division, Lufthansa Express, that promises passengers a better on-time record, faster check-in and a chance at bargain prices.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;Another innovation of Lufthansa Express will be bargain prices on late-night and short-notice flights. Passengers get a 55 percent discount savings on flights after 7:30 P.M., even without advance reservation, for example.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;The most controversial aspect of Lufthansa Express is something passengers are unlikely to hear much about: The starting pay for a crew on Express flights will be about 25 percent less than on traditional Lufthansa flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Another thread &lt;a href=&quot;http://forum.keypublishing.com/showthread.php?44482-Whatever-happened-to-the-quot-Lufthansa-Express-quot-concept&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; has a few minor other details. Interestingly enough, Amazon still has a &lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/com/B008N7MX48&quot; rel=&quot;nofollow noreferrer&quot; rel=&quot;nofollow noreferrer&quot;&gt;listing&lt;/a&gt; for a model LH Express 737 (out of stock).&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-09T15:30:07.690" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1639" PostTypeId="2" ParentId="1630" CreationDate="2014-02-09T16:44:05.853" Score="1" Body="&lt;p&gt;Like Ralgha said, larger aircraft with EFIS typically, don't have turn indicators or turn and slip.  Best judgment and flight director is use what one would use to make turns.  I'd have to dig into my manuals to make sure, but I think that a bank angle for standard rate is calculated up to a certain bank angle (I think less than 30 degrees) for pax comfort. Standard rate at 300kts is going to be a pretty bank angle.&lt;/p&gt;&#xA;" OwnerUserId="835" LastActivityDate="2014-02-09T16:44:05.853" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1640" PostTypeId="1" AcceptedAnswerId="1642" CreationDate="2014-02-09T17:22:15.817" Score="18" ViewCount="86310" Body="&lt;p&gt;When I first started flying jet aircraft, I found different instruments that measure temperature in different ways and it was quite confusing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between Outside Air Temperature, Ram Air Temperature (RAT), Total Air Temperature (TAT), Static Air Temperature (SAT), and any that I might have missed?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-09T17:49:39.200" LastActivityDate="2017-03-05T20:08:44.763" Title="What is the difference between OAT, RAT, TAT, and SAT?" Tags="&lt;aircraft-design&gt;&lt;flight-instruments&gt;&lt;temperature&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1641" PostTypeId="1" CreationDate="2014-02-09T17:26:44.947" Score="7" ViewCount="26145" Body="&lt;p&gt;I had never really heard of OpSpecs until I started a new flying job that was at a Part 135 company.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So for those people who are new to this (or are just interested):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is an Operation Specification and how does it relate to the actual CFR regulations?  &lt;/li&gt;&#xA;&lt;li&gt;What kinds of things are they used for?&lt;/li&gt;&#xA;&lt;li&gt;Who uses OpSpecs?&lt;/li&gt;&#xA;&lt;li&gt;In general terms, how is an OpSpec obtained?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-06-26T16:16:11.787" Title="What are Operations Specifications (OpSpecs)?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1642" PostTypeId="2" ParentId="1640" CreationDate="2014-02-09T18:17:39.027" Score="22" Body="&lt;p&gt;As you measure temperature moving at high velocities, your outside thermometer will measure a higher temp than what is actually outside (what a non-moving thermometer would get). That's because as the air rams into your thermometer it gets a little bit compressed, and that makes it heat up a little bit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Amazingly, some smart people have even calculated how much that &quot;ram rise&quot; is, and you can actually compensate (well, in theory) from the indicated temperature to calculate what the actual outside air temp is: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Ram~Rise=SAT\times0.2\times{M}^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $SAT$ is Static Air Temperature in Kelvin, $M$ is Mach number&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Problem is, not all instruments will compress that air in the same way, and not all of them will pick up this Ram Rise entirely. So they will publish a $K$, a ram-rise-coefficient (also called recovery factor) meaning how much of from the theoretical Ram Rise they actually pick up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(OAT/SAT) Static Air Temperature&lt;/strong&gt; = noted as $T_S$, actual temperature of the air outside, the same your thermometer will pick up if you were not moving &#xA;(say, in a balloon?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(RAT) Ram Air Temperature&lt;/strong&gt; = noted as $T_M$, actual measured temperature by your instrument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$RAT=SAT+k\times{Ram~Rise}$$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(TAT) Total Air Temperature&lt;/strong&gt; = noted as $T_T$, total temperature as measured by an instrument with $K$-coefficient of $1$.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$TAT=SAT+Ram~Rise$$&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2016-12-14T14:53:55.173" LastActivityDate="2016-12-14T14:53:55.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1643" PostTypeId="2" ParentId="1626" CreationDate="2014-02-09T21:36:22.257" Score="19" Body="&lt;p&gt;For both main and nose landing gear the main and really only consideration is where they can make space for the gear (there is no standard direction for retracting the main landing gear either; the Tu-154 retracts main gear rearwards into the &lt;a href=&quot;https://en.wikipedia.org/wiki/Anti-shock_body&quot; rel=&quot;noreferrer&quot;&gt;anti-shock body&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most common configuration is retracting nose gear forward, because it's easy to make space for it there leaving more space for the cargo hold. I don't think the air pressure during gravity extension plays any role in the decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most older Russian planes were however originally designed with glass nose seating navigator, so they did not have the room there. It was no longer the case with Tu-154 though. So they either had other equipment there or were simply used to making it retract rearward and didn't think about the advantage of changing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most common configuration for main gear is retracting it inward into the wing box, but note that the Tu-154 is exception there as well retracting the main gear into the rather large anti-shock bodies. Because they needed the anti-shock bodies they thought how to use them and there were not that many options.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="14897" LastEditDate="2016-06-07T12:47:43.200" LastActivityDate="2016-06-07T12:47:43.200" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1644" PostTypeId="2" ParentId="1641" CreationDate="2014-02-09T23:39:58.480" Score="12" Body="&lt;p&gt;Putting aside the legal definition for someone else, they are a set of rules that an operator (an airline for example) agrees to operate by. The FAA has to approve them. The ops specs can be more restrictive than applicable FAA regulations, but never less restrictive (as I remember). They cover many things, some of which (that I can remember) are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Type of equipment you're going to operate.&lt;/li&gt;&#xA;&lt;li&gt;Where you're going to operate.&lt;/li&gt;&#xA;&lt;li&gt;Extent to which VFR operations will be allowed.&lt;/li&gt;&#xA;&lt;li&gt;Types of navigation equipment permitted.&lt;/li&gt;&#xA;&lt;li&gt;Who you can offer your services to.&lt;/li&gt;&#xA;&lt;li&gt;Crew training required.&lt;/li&gt;&#xA;&lt;li&gt;Duty and flight time limitations.&lt;/li&gt;&#xA;&lt;li&gt;Disciplinary protocols to follow.&lt;/li&gt;&#xA;&lt;li&gt;Flight planning, dispatch, flight following requirements.&lt;/li&gt;&#xA;&lt;li&gt;Lists of who is who: chief pilot, flight standards director, etc.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are a lot more areas, but basically it's how you're going to operate your airline. The thing to remember is to give yourself as much leeway as possible. Don't do something stupid like saying that if someone fails an alcohol or drug test that you're simply doing to fire them. Provide for as much VFR operation as you can possibly get the FAA to agree to. Don't saddle yourself with impossible maintenance requirements if you have a mechanical problem in, say, Harare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ops specs are best written by someone who has been around the block many times. Write them poorly and you're going to cost yourself a lot of money that you would otherwise not have to spend. If you get a recalcitrant FAA inspector, it's worth fighting it out. Appeal as necessary until you get what you need. Don't be afraid to show up the ignorance of FAA newbies that may have been assigned. Also, remember that the FAA regions are not standardized. It may even be worth considering changing the region where you're technically based to get what you want.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-09T23:39:58.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1645" PostTypeId="1" AcceptedAnswerId="1650" CreationDate="2014-02-10T01:21:52.890" Score="13" ViewCount="5584" Body="&lt;p&gt;I've seen a few panel shots where the traditional turn coordinator has been replaced with a second artificial horizon, as shown below.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3Vskj.jpg&quot; alt=&quot;Panel with second horizon gyro&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefits seem obvious - if my artificial horizon failed I'd certainly like to have a fully functional back-up rather than a turn coordinator with no pitch information. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under what circumstances/conditions are these second horizon gyros acceptable as replacements?&lt;br&gt;&#xA;Are there any drawbacks that I should be aware of if I'm considering installing one.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="72" LastEditDate="2014-03-03T05:28:26.830" LastActivityDate="2015-06-29T21:05:25.287" Title="When/How may I replace the Turn Coordinator with an Artificial Horizon?" Tags="&lt;faa-regulations&gt;&lt;flight-instruments&gt;&lt;instrument-flight-rules&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1646" PostTypeId="1" AcceptedAnswerId="1664" CreationDate="2014-02-10T03:14:45.420" Score="11" ViewCount="3911" Body="&lt;p&gt;In a car, when you speed, you get pulled over, probably get a ticket, and you might get points added to your license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are air traffic rules enforced? Are there patrol planes that make sure no one is going over the speed limit? I have always been curious about that.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-02-10T17:25:21.763" Title="What happens when you break the rules while flying?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1647" PostTypeId="2" ParentId="1630" CreationDate="2014-02-10T03:25:13.487" Score="17" Body="&lt;p&gt;I'm only able to find the following about bank angles, which specifically refers to turns while in a holding pattern:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0503.html#Rn7352webb&quot;&gt;AIM 5-3-8&lt;/a&gt;6.(b):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;(b) Make all turns during entry and while holding at:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) 3 degrees per second; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) 30 degree bank angle; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) 25 degree bank provided a flight director system is used.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;&lt;br&gt;&#xA;  Use whichever requires the least bank angle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is also in the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/FAA-H-8261-1A.pdf&quot;&gt;Instrument Procedures Handbook&lt;/a&gt; which under *&lt;em&gt;High Performance Holding&lt;/em&gt; on page 3-25 says that a flight director has a bank angle limit of 25 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we use the above guidelines, then a flight director will use 3 degrees per second or 25 degrees of bank, whichever is less.  My calculations give us the following bank angles and associated rate of turns&lt;sup&gt;1&lt;/sup&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;        Standard Rate      Actual        Rate&#xA;TAS      Bank Angle      Bank Angle     of turn&#xA;80         13.17           13.17         3.00&#xA;120        19.34           19.34         3.00&#xA;160        25.08           25.00         2.99&#xA;200        30.33           25.00         2.39&#xA;240        35.07           25.00         1.99&#xA;280        39.31           25.00         1.71&#xA;320        43.10           25.00         1.49&#xA;360        46.48           25.00         1.33&#xA;400        49.48           25.00         1.20&#xA;440        52.15           25.00         1.09&#xA;480        54.54           25.00         1.00&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;As you can see, a jet travelling at 480 Knots TAS (not uncommon at altitude) would require almost a 55 degree bank angle to make a standard rate turn, which would be an amount considered by almost anyone as excessive. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When limited to 25 degrees of bank, this would result in a rate of turn of 1 degree per second (or a 6 minute turn).  Anything over 160 Knots TAS would be less than a standard rate turn, and once past 320 Knots TAS it  wouldn't even be a 1/2 standard rate turn.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the 1/2 Standard Rate, they often use the 1/2 BANK autopilot mode at high altitudes.  This would result in a rate of turn approximately halved, so a 360 degree turn would take 12 minute at the same 480 Knots TAS.  ATC expects the normal bank in the terminal environment though, so it isn't used at lower altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have said, transport category jets don't even have a rate of turn indicator (it isn't required by 14 CFR 25 if you have a third attitude indicator) and they simply fly bank angles.  Normal hand flying is limited to 30 degrees, which would allow a standard rate turn at a slightly higher airspeed, but then starts to taper off just the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot;&gt;Instrument Flying Handbook&lt;/a&gt; does include this little tidbit in the section on turn indicators on page 5-21:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The dial of these instruments is marked “2 MIN TURN.”  Some&#xA;  turn-and-slip indicators used in faster aircraft are  marked “4 MIN&#xA;  TURN.” In either instrument, a standard  rate turn is being made&#xA;  whenever the needle aligns with a  doghouse. A standard rate turn is&#xA;  3° per second. In a 2 minute  instrument, if the needle is one needle&#xA;  width either side of  the center alignment mark, the turn is 3° per&#xA;  second and the  turn takes 2 minutes to execute a 360° turn. In a 4&#xA;  minute  instrument, the same turn takes two widths deflection of the &#xA;  needle to achieve 3° per second.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So maybe at some point in the past it was more common (or maybe faster but-not-quite-as-fast-as-todays-jets) but you just don't see that anymore.  (It could be where all of the references to 1/2 standard rate turns come from though.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Math adapted from the formulas &lt;a href=&quot;http://www.luizmonteiro.com/Article_Bank_Angle_for_Std_Rate_03.aspx&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-10T05:12:18.217" LastActivityDate="2014-02-10T05:12:18.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1648" PostTypeId="1" CreationDate="2014-02-10T04:53:25.980" Score="6" ViewCount="6369" Body="&lt;p&gt;Part 135 and (I believe) Part 121 operations all have a requirement to use a source of weather that has been approved by the U.S. National Weather Service:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e8faa6e940e3734588f3db72db5f76e5&amp;amp;node=14:3.0.1.1.11.4.3.7&amp;amp;rgn=div8&quot;&gt;§135.213&lt;/a&gt;   Weather reports and forecasts.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Whenever a person operating an aircraft under this part is&#xA;  required to use a weather report or forecast, that person shall use&#xA;  &lt;strong&gt;&lt;em&gt;that of the U.S. National Weather Service, a source approved by the&#xA;  U.S. National Weather Service, or a source approved by the&#xA;  Administrator&lt;/em&gt;&lt;/strong&gt;. However, for operations under VFR, the pilot in command&#xA;  may, if such a report is not available, use weather information based&#xA;  on that pilot's own observations or on those of other persons&#xA;  competent to supply appropriate observations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does the FAA or the U.S. National Weather Service maintain a list of weather providers that have been approved and are legal for us to use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, then how do we know whether a particular source has been approved?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-10T06:35:00.363" Title="What sources of weather are approved by the U.S. National Weather Service?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;weather&gt;&lt;far-135&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1649" PostTypeId="2" ParentId="1648" CreationDate="2014-02-10T05:57:17.047" Score="7" Body="&lt;p&gt;There is an ongoing issue with this, as far as I am aware. First off, this does not apply to part 91, and nothing does as far as I am aware: you can get your weather from anywhere, but having it on record with FSS or DUATs gives you a little more padding if something goes wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're going to get weather online, which most large operations do, the FAA requires air carriers to get weather information only from Qualified Internet Communications Providers (QICP). This is outlined under &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_00-62.pdf&quot;&gt;AC 00-62&lt;/a&gt;. Or rather, it &lt;em&gt;was&lt;/em&gt; outlined there. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/Cancellation_Memno_AC_00-62.pdf&quot;&gt;00-62 was quietly cancelled in mid 2013.&lt;/a&gt; In addition, the only list of QICPs (which would have answered your question) I know/knew about was removed from the FAA website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few weeks after it was cancelled I found out about it and called the FSDO to ask (Memphis or Louisville, I don't remember which). The man who should know told me that I knew about as much as he did. Their regional offices hadn't told them anything, and he was telling everyone to continue using the qualified service they were previously using until they learned more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not called them back since, but after a quick search, I only found &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/notice/n_8900.210.pdf&quot;&gt;this OpSpec document&lt;/a&gt; and one that it supersedes from a few months before (8900.199). There is also a newer one in the series (8900.242) but it seems to have no information relevant to the question. I must adimit that this document is a bit over my head, but it seems that they did an overhaul of the weather regulations regarding 135 and 121, and that use of a QICP is no longer required. So I take it that unless your carrier is only certified to use a certain system, you're now allowed to use whatever you want to get the weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/&quot;&gt;You can read those documents here&lt;/a&gt;, the three I mention were published under AFS-200. Search for that and you'll find them and more.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So I did some more research:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v03%20tech%20admin/chapter%2026/03_026_002.pdf&quot;&gt;Check out 8900.1 Ch 26 Section 2. Regulatory Sources of Aviation Weather Information and Aviation Weather Information Systems – Parts 91K, 121, and 135&lt;/a&gt;. The first bit has a good overview of all the weather products and their intended purposes. Relevance to the question starts at 3-2073(A) &lt;em&gt;Weather Reports Prepared by the NWS or a Source Approved by the NWS.&lt;/em&gt; (page 6 in the PDF version).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much further down it says (&lt;em&gt;in reference to &lt;strong&gt;part 135, 121, 125, etc&lt;/strong&gt; certificate holders only&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;B. Accessing Weather Information via the Public Internet.&lt;/strong&gt; Certificate holders and &#xA;  program managers often access weather information via the public Internet. When accessing &#xA;  weather information this way, certificate holders and program managers are required to use &#xA;  weather information that is provided by a weather source authorized by regulation, or approved &#xA;  by the Administrator, and is listed in the certificate holders’/program managers’ &#xA;  OpSpecs/MSpecs. In the past, the FAA maintained a list of approved QICP. However, the FAA &#xA;  no longer approves QICPs. The FAA has canceled AC 00-62, Internet Communications of &#xA;  Aviation Weather and NOTAMS, and no longer maintains a list of approved QICPs. Certificate &#xA;  holders and program managers using the public Internet to access weather information are &#xA;  responsible for ensuring accurate and timely delivery of information without data corruption &#xA;  during the transmission.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's all pretty cut and dry, I think, but keep in mind that those OpSpec papers mention that everything in 8900.1 Ch. 26 is under review and has been edited recently and will be further edited in the near future.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-02-10T06:35:00.363" LastActivityDate="2014-02-10T06:35:00.363" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1650" PostTypeId="2" ParentId="1645" CreationDate="2014-02-10T06:38:40.627" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC91-75.pdf&quot; rel=&quot;nofollow&quot;&gt;Check out AC 91-75&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe it has everything you're looking for. It seems the FAA really doesn't like turn coordinators these days:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“[T]he FAA believes, and &#xA;  all other commenters apparently agree … the rate-of-turn indicator is no &#xA;  longer as useful as an instrument which gives both horizontal and vertical &#xA;  attitude information.” &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which is completely true...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't see a drawback, really. You'll also have to buy a slip-skid indicator (it seems that most replacement attitude indicators can be ordered bundled with one.), so you're really not losing anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: The other posts and comments raise some good discussion, I suggest reading those as well.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-02-11T18:47:46.233" LastActivityDate="2014-02-11T18:47:46.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1651" PostTypeId="2" ParentId="1646" CreationDate="2014-02-10T06:46:30.083" Score="5" Body="&lt;p&gt;Did you get caught? If yes, you face enforcement action. Maybe a fine, maybe a revocaation or suspension of your certificate for a while, maybe jail time. If no, you might feel guilty enough to &lt;a href=&quot;http://asrs.arc.nasa.gov/overview/summary.html&quot; rel=&quot;noreferrer&quot;&gt;send in an ASRS form.&lt;/a&gt; This greatly decreases your chances of getting punished later if someone finds out, unless they also find out you intentionally broke the rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Honestly, there are a ton of rules in aviation but they're enforced by a fairly small agency who isn't even that vigilant when it comes to the little guys. Kind of the opposite of the police on the ground. But in all, it's pretty easy to do almost whatever you want and not even break a rule. Use common sense to stay safe and usually you're within the law in the air.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-10T06:46:30.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1652" PostTypeId="2" ParentId="537" CreationDate="2014-02-10T06:56:46.250" Score="13" Body="&lt;p&gt;Lots of good feedback here.  Whenever I am compelled to call the ATC to confirm a clearance or instruction, or if I suspect I was simply forgotten, I just carefully word it as though I may be the one who missed their call even if I'm 99% certain I didn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I'd never say, &quot;Tower N1234 sitting at the threshold of 27 ... did you forget about me?&quot;  (Accusative)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rather, &quot;Tower N1234 sitting at the threshold of 27 ... did I miss your clearance for takeoff by chance?&quot;  (Inquisitive)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many towered airports ... especially Class Delta ... have their own little methods of madness or traditions or idiosyncrasies that you won't know the first or second time in.  I recently flew in and out of Fort Myers Page Field.  Normally, I'll never switch from ground to tower until told to do so.  I taxied to the runway threshold, did a runup, then called ground to say I was ready to go ... and &quot;Shall I switch to the tower frequency?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answer, &quot;N1234, at this airport, whenever you arrive at the threshold you may go ahead and switch to the tower frequency and let 'em know when you're ready.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK ... fine ... cordial ... polite ... but certainly not by the book.&lt;/p&gt;&#xA;" OwnerUserId="699" LastActivityDate="2014-02-10T06:56:46.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1653" PostTypeId="1" AcceptedAnswerId="1678" CreationDate="2014-02-10T06:58:46.370" Score="6" ViewCount="507" Body="&lt;p&gt;I was once (like ten years ago) on a transpacific flight with Northwest from KIX/RJBB to KDTW on a Boeing 747 and our flight as delayed at the gate for about an hour because of some issue with a &quot;floating horizon&quot; (I remembered incorrectly, the issue was a &quot;artificial horizon&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is that a malfunction with the attitude indicator? What exactly went wrong? It sounded like they fixed it by swapping out a component, maybe the instrument itself?&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="567" LastEditDate="2014-11-20T13:52:23.247" LastActivityDate="2014-11-20T13:52:23.247" Title="What kind of malfunction is an &quot;artificial horizon&quot;?" Tags="&lt;aircraft-maintenance&gt;&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1654" PostTypeId="2" ParentId="1645" CreationDate="2014-02-10T08:59:12.630" Score="4" Body="&lt;p&gt;I can think of a couple of things, the most prominent is the power source. Turn indicators are usually electrically powered, whereas attitude indicators are vacuum powered, and the idea is to provide redundancy should either power source fail. This is not always the case though, and if your second attitude indicator is powered electrically, that's obviously a non-issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second thing is the absence of a ROT indication, forcing you to calculate the correct bank angle for a standard rate turn should you ever really need one. The only situation I can think of where it is imperative that you can do a standard rate/half rate turn is a no-gyro approach in which case you've probably also lost your vacuum source, and you don't want to start playing mind games, but it's not as crucial as the power source redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for whether it's acceptable, StallSpin seems to have that covered. The pictured second attitude indicator is fitted with a slip indicator, so that should cover that aspect.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-02-10T08:59:12.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1656" PostTypeId="1" AcceptedAnswerId="1663" CreationDate="2014-02-10T13:29:43.260" Score="12" ViewCount="721" Body="&lt;p&gt;Has anyone come across any academic study on the effects of information provided by &quot;glass&quot; instrumentation that affects, favorably or unfavorably, situational awareness, skill and performance, and decision making?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related question:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/3577/where-does-the-term-steam-cockpit-come-from&quot;&gt;Where does the term &amp;#39;steam cockpit&amp;#39; come from?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="838" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-03-08T03:09:43.847" Title="Are there any studies on the safety of glass versus steam instruments?" Tags="&lt;safety&gt;&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1657" PostTypeId="1" CreationDate="2014-02-10T13:48:00.823" Score="9" ViewCount="1429" Body="&lt;p&gt;So Justin Bieber was in the news again a couple of days ago:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://entertainment.time.com/2014/02/05/justin-bieber-plane-marijuana-arrests/&quot;&gt;Pilots on Justin Bieber’s Plane Had to Wear Masks Because of Pot Smoke&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are pilots &lt;strong&gt;legally obligated&lt;/strong&gt; to do in a situation like this where the passengers (allegedly) are doing drugs or any other illegal activity?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notify ATC, call 911, or land immediately?  Are any of these required or can you tell them to stop and if they comply you are good?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any good recommendations on how to handle the passengers?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-10T16:10:03.950" LastActivityDate="2014-02-10T19:15:50.547" Title="What should pilots do if they observe illegal activity onboard an aircraft?" Tags="&lt;faa-regulations&gt;&lt;passenger&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1658" PostTypeId="2" ParentId="1657" CreationDate="2014-02-10T13:59:17.043" Score="4" Body="&lt;p&gt;I think a lot would depend on the type of illegal activity observed.  For example, if someone was getting injured or worse, that would mean the crew would need to take immediate and aggressive action, which would include possibly putting themselves in some danger to protect the victim, at least to a certain degree.  That said, getting the plane down safely would be higher priority for safety all the way around so protecting the victim needs to be weighed against the risk of getting injured to the point the pilot can no longer fly the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Bieber's case, escalating the situation by trying to intervene would only create risk of the crew being injured and then unable to bring the plane down with no real upside.  Putting out a warning, then proceeding to a suitable airport immediately would seem to be the most prudent course of action.  &lt;/p&gt;&#xA;" OwnerUserId="838" LastEditorUserId="838" LastEditDate="2014-02-10T18:00:17.317" LastActivityDate="2014-02-10T18:00:17.317" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1659" PostTypeId="1" AcceptedAnswerId="1662" CreationDate="2014-02-10T14:30:16.323" Score="29" ViewCount="38416" Body="&lt;p&gt;This is something I've wondered about for a long time.  On really large airplanes, like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400&quot;&gt;747-400&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380&quot;&gt;A380&lt;/a&gt; for example, I would assume that the weight of the passengers on board is a significant to the flight characteristics of the plane. And it seems like it would be pretty easy to put all the passengers in an odd place (like all at the front or back) and as a result significantly change the flight characteristics of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, assuming I'm right (tell me if I'm not), how do commercial aircraft counter this problem? Do they do their best to distribute passengers throughout the craft with seat assignments? Or do they have ballast they can move around (like fuel ballast)?  Or is the weight shift not significant enough to warrant anything along these lines?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2015-02-13T15:59:29.430" LastActivityDate="2019-04-10T04:26:45.827" Title="Is passenger weight distribution important on a commercial flight?" Tags="&lt;weight-and-balance&gt;&lt;commercial-operations&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1660" PostTypeId="2" ParentId="1659" CreationDate="2014-02-10T14:51:47.350" Score="0" Body="&lt;p&gt;On an under-booked flight the passengers are spread around through seat assignments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emergency exits are kept clear, and if someone tries to sneak there for the extra leg room they are asked to return to their seats (at least the underage passengers are).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: I was on such a underbooked short haul flight for a school trip, we plus a handful of other passengers only filled a third to half of the plane. On the return flight we coincided with another school trip returning and there was a clear split between our class and the other school.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="849" LastEditDate="2014-02-11T20:42:29.680" LastActivityDate="2014-02-11T20:42:29.680" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1661" PostTypeId="2" ParentId="1659" CreationDate="2014-02-10T15:38:51.493" Score="6" Body="&lt;p&gt;I'm not sure how sensitive/flexible the widebodies are but on the smaller regional jets, the crew will use the &quot;whizwheel&quot; to determine CG location.  The aircraft is divided up into n regions (depends on how large/long the aircraft is).  If the CG is too far forward, the crew will require that a few passengers to move from the forward region to the aft regions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm certain that the same thing happens on the larger jets but the crews receive weight an balance from dispatch or whomever does it for them for the purposes of review.&lt;/p&gt;&#xA;" OwnerUserId="835" LastActivityDate="2014-02-10T15:38:51.493" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1662" PostTypeId="2" ParentId="1659" CreationDate="2014-02-10T15:39:01.160" Score="32" Body="&lt;p&gt;On the EMB-145 the passenger cabin was split into 5 zones and we were given passenger totals in each zone from the flight attendant prior to leaving the gate.  If balance is off (this happened quite rarely for us) you would tell the flight attendant &quot;I need 2 passengers from zone 5 moved to zone 1&quot; or &quot;I need a passenger from zone 3 moved to zone 2&quot; or some other similar instruction.  The flight attendant would solicit volunteers and if no one did, they would instruct someone to move.  The move was only for takeoff and once airborne they could go back to their normal seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After moving passengers we would re-calculate the weight and balance to verify we were in the envelope and set takeoff trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar methods are used in larger airplanes with the cabin split into zones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only time we would use ballast is when we had a full cabin and not enough bags in the cargo (not common).  In those cases we would ask ops for ballast and they would put something in the cargo.  They would try to make it useful if an outstation needed something else they would just load 50 lb bags of sand.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-10T15:39:01.160" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1663" PostTypeId="2" ParentId="1656" CreationDate="2014-02-10T16:26:54.790" Score="6" Body="&lt;p&gt;The FAA released a 70 page report back in 2003 titled &lt;a href=&quot;https://www.faa.gov/training_testing/training/fits/research/media/TAA%20Final%20Report.pdf&quot; rel=&quot;nofollow&quot;&gt;General Aviation Technically Advanced Aircraft FAA – Industry Safety Study&lt;/a&gt; which basically says that the overall accident rate of the two types of airplanes are almost the same.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They found that the &quot;available safety&quot; of Technically Advanced Aircraft (TAA) is greater than non-TAA aircraft, however in emergency situations pilots often were not aware of the resources available. To offset this, they recommend (among other things) more training for pilots before flying TAA's so that they actually have the safety related aspects available to them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here were their official findings:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Team Findings:&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The safety problems found in the accidents studied by the Team are  typical of problems that occurred after previous introductions of new &#xA;  aircraft technology and all also reflect typical GA pilot judgment&#xA;  errors  found in analysis of non-TAA accidents &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Previous safety problems similar to those identified in this Study have  been remedied through a combination of improved training and, in&#xA;  the  case of new aircraft capabilities, pilot screening (i.e.,&#xA;  additional insurance  company requirements of pilot experience). &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The predominant TAA-system-specific finding is that the steps required to  call up information and program an approach in&#xA;  IFR-certified GPS  navigators are numerous, and during high workload&#xA;  situations they can  distract from the primary pilot duty of flying&#xA;  the aircraft. MFDs in the  accident aircraft did not appear to present&#xA;  a complexity problem. The  Team also believes that PFDs, while not&#xA;  installed in any of the accident  aircraft and just now becoming&#xA;  available in TAAs, similarly are not likely to  present a complexity&#xA;  problem. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;TAAs provide increased “available safety”, i.e., a potential for increased  safety. However, to actually obtain this available safety,&#xA;  pilots must  receive additional training in the specific TAA systems&#xA;  in their aircraft that  will enable them to exploit the opportunities&#xA;  and operate within the  limitations inherent in their TAA systems. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The template for securing this increased safety exists from the  experiences with previous new technology introductions –the current &#xA;  aircraft model-specific training and insurance requirements applicable&#xA;  to  high-performance single and multi engine small airplanes. However,&#xA;  the  existing training infrastructure currently is not able to provide&#xA;  the needed  training in TAAs. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Effective and feasible interventions have been identified, mostly  recommending improvements in training, and effective implementation &#xA;  mechanisms for the recommended interventions exist. Therefore, TAA &#xA;  safety problems can be addressed, and the additional available safety&#xA;  of  TAAs to address traditional causes of GA accidents can be realized&#xA;  as  well.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;APOA has a nice &lt;a href=&quot;https://www.aopa.org/News-and-Video/All-News/2012/March/1/Report-compares-glass-analog-panel-safety.aspx&quot; rel=&quot;nofollow&quot;&gt;summary here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-10T16:51:56.607" LastActivityDate="2014-02-10T16:51:56.607" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1664" PostTypeId="2" ParentId="1646" CreationDate="2014-02-10T17:17:40.440" Score="12" Body="&lt;p&gt;When you break the rules while flying, it falls into one of two categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Only you know about it&lt;/li&gt;&#xA;&lt;li&gt;The FAA knows about it&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In either case, the very first thing you do is file a &lt;a href=&quot;http://asrs.arc.nasa.gov/report/caveat.html?formType=general&quot;&gt;NASA ASRS form&lt;/a&gt;.  You might ask, why does NASA care about airplanes?  They are acting as an uninterested 3rd party to your actions, and collate statistics from this information.  If the FAA becomes aware of your actions, the presence of an ASRS form in many cases limits the action the FAA can take against you.  It is always worth filling out and I have filled out a few myself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case the FAA knows about it, how do they know about it?  This typically happens when you are in radar control and do something wrong or are on the ground and do something wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples of this are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight plan in the FMS is incorrect and you make a turn off of your cleared course.  The controller will see this.&lt;/li&gt;&#xA;&lt;li&gt;You taxi incorrectly &lt;/li&gt;&#xA;&lt;li&gt;Runway incursion &lt;/li&gt;&#xA;&lt;li&gt;Climb / descend through your cleared altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In most of these cases, the controller will just correct you.  In cases that result in a loss of separation or a runway incursion, you may get a phone number from the controller to call when you land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less commonly, something you do may be witnessed by an FAA inspector -- you buzzed the tower when he was on the ramp watching you.  Or perhaps he watched you get into a plane and fly off without performing a pre-flight inspection.  Perhaps you were ramp checked and something wasn't right with you or the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all of the above cases, if you are able to file an ASRS form, do it.  If you do something that may be severe and are a member of AOPA, call their legal team and discuss the situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the FAA responds to something they know about, it can range from a controller talking to you over the phone up to certificate action (suspension, revoked) to the infamous &quot;709 ride&quot;, in which the FSDO administers a checkride and decides which, if any, ratings you keep and which you lose.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-10T17:25:21.763" LastActivityDate="2014-02-10T17:25:21.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1666" PostTypeId="2" ParentId="1657" CreationDate="2014-02-10T18:19:22.520" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol2/xml/CFR-2012-title14-vol2-sec91-19.xml&quot; rel=&quot;nofollow&quot;&gt;FAR 91.19&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.19&#xA;      Carriage of narcotic drugs, marihuana, and depressant or stimulant drugs  or substances.&#xA;      (a) Except as provided in paragraph (b) of this section, no person may &#xA;  operate a civil aircraft within the United States &lt;strong&gt;with&#xA;  knowledge&lt;/strong&gt; that narcotic drugs, marihuana, and depressant or&#xA;  stimulant drugs or substances as defined in Federal or State statutes&#xA;  are carried in the aircraft.&#xA;      (b) Paragraph (a) of this section does not apply to any carriage of narcotic drugs, marihuana, and depressant or stimulant drugs or&#xA;  substances authorized by or under any Federal or State statute or by&#xA;  any Federal or State agency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the FAA seems to say that if you know about it than you should not take the flight. This makes it seem that if you started to smell pot smoke while you flying you now have knowledge of it and should take some action. Also &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol2/xml/CFR-2012-title14-vol2-sec91-17.xml&quot; rel=&quot;nofollow&quot;&gt;FAR 91.17&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.17&#xA;      Alcohol or drugs.&#xA;      (a) No person may act or attempt to act as a crewmember of a civil aircraft—&#xA;      (1) Within 8 hours after the consumption of any alcoholic beverage;&#xA;      (2) While under the influence of alcohol;&#xA;      (3) While using any drug that affects the person's faculties in any way contrary to safety; or&#xA;      (4) While having an alcohol concentration of 0.04 or greater in a blood or breath specimen. Alcohol concentration means grams of alcohol&#xA;  per deciliter of blood or grams of alcohol per 210 liters of breath.&#xA;      (b) Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner&#xA;  or physical indications that the individual is under the influence of&#xA;  drugs (except a medical patient under proper care) to be carried in&#xA;  that aircraft.&#xA;      (c) A crewmember shall do the following:&#xA;      (1) On request of a law enforcement officer, submit to a test to indicate the alcohol concentration in the blood or breath, when—&#xA;      (i) The law enforcement officer is authorized under State or local law to conduct the test or to have the test conducted; and&#xA;      (ii) The law enforcement officer is requesting submission to the test to investigate a suspected violation of State or local law&#xA;  governing the same or substantially similar conduct prohibited by&#xA;  paragraph (a)(1), (a)(2), or (a)(4) of this section.&#xA;      (2) Whenever the FAA has a reasonable basis to believe that a person may have violated paragraph (a)(1), (a)(2), or (a)(4) of this&#xA;  section, on request of the FAA, that person must furnish to the FAA&#xA;  the results, or authorize any clinic, hospital, or doctor, or other&#xA;  person to release to the FAA, the results of each test taken within 4&#xA;  hours after acting or attempting to act as a crewmember that indicates&#xA;  an alcohol concentration in the blood or breath specimen.&#xA;      (d) Whenever the Administrator has a reasonable basis to believe that a person may have violated paragraph (a)(3) of this section, that&#xA;  person shall, upon request by the Administrator, furnish the&#xA;  Administrator, or authorize any clinic, hospital, doctor, or other&#xA;  person to release to the Administrator, the results of each test taken&#xA;  within 4 hours after acting or attempting to act as a crewmember that&#xA;  indicates the presence of any drugs in the body.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Any test information obtained by the Administrator under paragraph (c) or (d) of this section may be evaluated in determining a&#xA;  person's qualifications for any airman certificate or possible&#xA;  violations of this chapter and may be used as evidence in any legal&#xA;  proceeding under section 602, 609, or 901 of the Federal Aviation Act&#xA;  of 1958.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that as the pilot you need to stay sober and this likely why the pilots of the aircraft donned their (I'm &lt;em&gt;assuming&lt;/em&gt; oxygen) masks. This however, is only the Federal &lt;em&gt;Aviation&lt;/em&gt; Regulations. That is, Title 14 (Aeronautics and Space) of the Code of Federal Regulations. So even though the &lt;strong&gt;FAA&lt;/strong&gt; might take a blind eye to you if your passengers had marijuana or cocaine or some other illegal substance &lt;strong&gt;and you had no knowledge&lt;/strong&gt; it still doesn't mean that Federal, State, or local law enforcement couldn't try to nail you on possession charges. I would say pretty safely that as the pilot as soon as you find out there are illegal drugs on board it is your obligation to reduce exposure to the crew and to discontinue flight as soon &lt;strong&gt;AS SAFELY&lt;/strong&gt; possible.&lt;/p&gt;&#xA;" OwnerUserId="391" LastEditorUserId="391" LastEditDate="2014-02-10T19:15:50.547" LastActivityDate="2014-02-10T19:15:50.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1667" PostTypeId="2" ParentId="1657" CreationDate="2014-02-10T18:47:08.157" Score="3" Body="&lt;p&gt;Disclaimer: I am neither aviator nor lawyer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think there is any special law regarding illegal activity on board of an aircraft. So:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the activity creates a safety risk, the commander should do whatever they evaluate as the safest way to continue or end the flight. Flying the aircraft is a priority, but if lives of the pilots are in danger, they should do whatever they can to defend themselves including extreme manoeuvres (like &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Express_Flight_705&quot; rel=&quot;nofollow&quot;&gt;FedEx 705&lt;/a&gt;) or the reduction of cabin altitude mentioned in the comments (passenger oxygen masks will fall out automatically, but one can't move around cabin while breathing from those, so it still might provide useful help).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Otherwise it's just the general criminal law that applies. Most jurisdictions require that anybody who finds about serious crime reports it except if they believe their close relative might have committed it. This obligation applies to murder (including attempted) and treason and might apply to other crimes depending on the country. For international flights the country of operator should be applicable, but the legal terms unfortunately seem to be a mess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to how you report it, the most efficient way would be to tell ATC that you had a crime on board and request police to meet you on landing. Unless you can't do that because the offender would hear it and endanger the aircraft more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether to land immediately depends on the same concern. Expedient landing will tip the offender that they are going to be arrested and they may fight. There was recently a case when police found who committed a murder, but he just boarded a plane from Vienna to New York. They told the crew, but elected to continue the flight so he didn't suspect they know about him though it made it more difficult for the justice than arresting him on the EU ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-02-10T18:47:08.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1668" PostTypeId="2" ParentId="1645" CreationDate="2014-02-10T19:21:41.703" Score="10" Body="&lt;p&gt;The &lt;a href=&quot;http://www.av8n.com/how/&quot; rel=&quot;noreferrer&quot;&gt;How It Flies&lt;/a&gt; in section on &lt;a href=&quot;http://www.av8n.com/how/htm/aoastab.html#sec-spiral-recovery&quot; rel=&quot;noreferrer&quot;&gt;Spiral Dive Recovery&lt;/a&gt; mentions:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If you don’t have good outside references, you &lt;strong&gt;should &lt;em&gt;not&lt;/em&gt; rely on the attitude indicator (artificial horizon).&lt;/strong&gt; The attitude indicator contains a gyro mounted on ordinary mortal gimbals, which can only accommodate a limited range of pitch and bank angles. A steep spiral can easily cause the gyro to tumble, whereupon it will need several minutes of relatively straight and level flying before it can re-erect itself. Military aircraft have non-tumbling attitude indicators, but you’re not likely to find such things in a rented Skyhawk. Therefore, &lt;strong&gt;you should roll the wings level by reference to the rate-of-turn gyro.&lt;/strong&gt;&lt;sup&gt;8&lt;/sup&gt; Being a rate gyro (as opposed to a free gyro) it has no gimbals, and therefore can’t possibly suffer from gimbal lock.&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;8&lt;/sup&gt; That is, the turn needle or turn coordinator, whichever you happen to have.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And in section on &lt;a href=&quot;http://www.av8n.com/how/htm/spins.html#sec-spin-recovery&quot; rel=&quot;noreferrer&quot;&gt;Spin Recovery&lt;/a&gt; it adds:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If you get into a spin in instrument conditions, you should &lt;strong&gt;rely primarily&lt;/strong&gt; on the airspeed indicator &lt;strong&gt;and the rate-of-turn gyro.&lt;/strong&gt; The inclinometer ball cannot be trusted; it is likely to be centrifuged away from the center of the airplane — giving an indication that depends on where the instrument is installed, telling you nothing about the direction of spin. The artificial horizon (attitude indicator) cannot be trusted since it may have tumbled due to gimbal lock. It is better to trust the rate-of-turn, which cannot possibly suffer from gimbal lock, since it has no gimbals. Remember, it is a rate gyro (not a free gyro), so it doesn’t need gimbals.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you have good enough artificial horizon designed to avoid gimbal-lock, the you don't need turn coordinator. But with ordinary artificial horizon the turn coordinator combined with vertical speed indicator (despite it's problems like rather slow reaction time) are useful backup for recovering from in-flight upsets.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-10T19:31:30.847" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1669" PostTypeId="1" AcceptedAnswerId="1670" CreationDate="2014-02-10T20:51:42.047" Score="26" ViewCount="20544" Body="&lt;p&gt;One of the enforcement actions that FAA can take against a pilot is known as a &quot;709 ride&quot; in which your certifications and rating are reevaluated by the FAA.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the regulatory basis for this exam?&lt;/li&gt;&#xA;&lt;li&gt;What are the possible outcomes of this examination?&lt;/li&gt;&#xA;&lt;li&gt;When is this enforcement action used against a pilot?&lt;/li&gt;&#xA;&lt;li&gt;What happens during a 709 ride? (maneuvers, oral examination, etc)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastEditorUserId="1696" LastEditDate="2015-04-21T15:31:11.570" LastActivityDate="2015-04-21T15:31:11.570" Title="What is a 709 ride?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1670" PostTypeId="2" ParentId="1669" CreationDate="2014-02-10T22:06:38.603" Score="22" Body="&lt;p&gt;The regulatory basis for the exam comes from &lt;a href=&quot;http://www.law.cornell.edu/uscode/text/49/44709&quot;&gt;49 USC 44709&lt;/a&gt; (hence the name), which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) The Administrator of the Federal Aviation Administration may reinspect at any time a civil aircraft, aircraft engine, propeller, appliance, design organization, production certificate holder, air navigation facility, or air agency, or reexamine an airman holding a certificate issued under section 44703 of this title. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The outcomes and procedures are handled as show &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=6B5517EC9C4A91258525734F00766681&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Possible Outcomes&lt;/strong&gt; (&lt;em&gt;5-1424&lt;/em&gt;, &lt;em&gt;5-1428&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;: As shown in 5-1428, the results are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Issuance of a letter of results to the airman;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Possible issuance of a Temporary Airman Certificate; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Possible downgrade of the airman’s certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the airman &lt;em&gt;satisfactorily completes the reexamination&lt;/em&gt; (5-1424(A)), then the inspector will issue a letter of results. If the certificate had been temporarily suspended, then the &lt;code&gt;FSDO forwards a copy of the letter of results to the Regional Assistant Chief Counsel, who then takes appropriate action to terminate the suspension. If the airman needs use of the certificate immediately, the Regional Assistant Chief Counsel may authorize the inspector to issue a temporary certificate that bears all ratings and limitations from the original certificate.&lt;/code&gt; Otherwise, if the certificate had &lt;em&gt;not&lt;/em&gt; been suspended, the airman is free &lt;code&gt;to exercise the privileges of the certificate and/or ratings.&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airman does &lt;em&gt;not satisfactorily complete the reexamination&lt;/em&gt; (5-1424(B)), then:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airman must be informed in detail of each deficiency. Additionally, if the airman’s certificate had been temporarily deposited at the FSDO and the temporary deposit term is nearing expiration, a decision must be made to suspend the certificate or to extend the temporary deposit period for another 30 days. If, in the opinion of the inspector, the airman could successfully complete another reexamination by obtaining additional instruction, every effort must be made to encourage the airman to do so.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Depending on what the inspector decides, one of two things happens:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1) When the inspector decides to allow the airman additional time, the inspector takes the airman's certificate for temporary deposit at the FSDO and issues a temporary certificate. The temporary certificate must have a limitation against carrying passengers and a 30-day expiration date. The airman has 30 days in which to practice or obtain additional dual instruction before being reexamined again.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2) If the inspector determines the airman is unable to establish qualification to hold the certificate or rating, legal enforcement action must be taken to revoke the airman’s certificate and/or ratings. (See FAA Order 2150.3, Chapter 8.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When is the enforcement action issued?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is mostly covered in the above sections. Essentially, if you are not found deficient, a revocation of your suspension will begin to be processed or you can just proceed on your merry way. If you are found deficient, then you will either be immediately be issued a temporary certificate with limitations so you can practice to pass another re-exam, or your certificate will revoked as soon as can be legally done (presumably the inspector will tell you not to fly, but I don't have backing for that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What happens during a 709 ride?&lt;/strong&gt; (&lt;em&gt;5-1423&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part (A) of 5-1423 deals with this, and states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Extent of Reexamination.&lt;/strong&gt; The inspector should test the airman only in the areas specified in the letter of notification. However, if other deficient areas are noted during the reexamination, these would also be the basis for failure of the test. For example, during a reexamination when the airman was to be tested on the ability to recognize and recover from stalls, the inspector noted that on takeoff the airman over-rotated to a dangerously high pitch attitude, requiring the inspector to take corrective action. In this situation the reexamination should be discontinued, and the airman should be informed of failing the test because of deficient skills exhibited while en route to demonstrate the maneuvers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Part (B) notes that the inspector can place special emphasis on certain areas based on the reason for the letter being issued. You can fail if you are unqualified for &lt;em&gt;any&lt;/em&gt; maneuver contained in the PTS for the certificate/rating you are being tested for, as Part (C) notes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part (D) notes that the test does not have to be flight-based, though presumably one that &lt;em&gt;did&lt;/em&gt; would have some portion of oral examination. (Part (E) allows the test to be taken in a simulator, if it is requested by the airman and approved by the inspector).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Knowledge Reexamination.&lt;/strong&gt; The reexamination may be conducted using an oral or knowledge test, devised by the inspector, if the area to be reexamined is one of knowledge rather than skill or flight proficiency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-02-10T22:06:38.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1671" PostTypeId="2" ParentId="1669" CreationDate="2014-02-10T22:06:39.733" Score="4" Body="&lt;p&gt;Reference: &lt;a href=&quot;http://www.law.cornell.edu/uscode/text/49/44709&quot; rel=&quot;nofollow&quot;&gt;http://www.law.cornell.edu/uscode/text/49/44709&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulatory basis appears to be 49 U.S. Code § 44709 - Amendments, modifications, suspensions, and revocations of certificates&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When might a 709 ride happen:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Administrator of the Federal Aviation Administration may reinspect at any time a civil aircraft, aircraft engine, propeller, appliance, design organization, production certificate holder, air navigation facility, or air agency, or reexamine an airman holding a certificate issued under section 44703 of this title.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally only as the result of some (alleged) violation. I've found references to CFIs receiving 709's as a result of actions performed by not only their students, but former students as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possible outcomes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA may amend, modify, suspend, or revoke the certificate in question.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What happens:&#xA;I haven't found a definitive source to this but rather anecdotal evidence to suggest the pilot being examined is subject to the PTS of the certificate in question, but this is not to imply that a full check ride will be required. Rather, the extent of the examination is up to the inspector.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-02-10T22:06:39.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1672" PostTypeId="1" AcceptedAnswerId="1675" CreationDate="2014-02-10T22:17:53.080" Score="9" ViewCount="1216" Body="&lt;p&gt;In reference to &lt;a href=&quot;http://edition.cnn.com/2014/02/05/showbiz/justin-bieber-marijuana-flight/&quot;&gt;this incident&lt;/a&gt; by a certain (in)famous artist, i'm wondering &lt;strong&gt;how effective modern aircraft are at clearing smoke&lt;/strong&gt; for single aisle commercial aircraft such as B737/A320 or a business jet like in the story? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Which direction does the airflow in a cabin move? Top to bottom? &lt;/li&gt;&#xA;&lt;li&gt;How far are people effected by secondhand smoke if somebody lights a cigarette? Would it be within a one-meter range or would people notice across the whole cabin?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-10T22:47:19.587" LastActivityDate="2014-02-10T23:24:09.247" Title="How effective are modern aircraft at clearing smoke?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1673" PostTypeId="1" AcceptedAnswerId="1674" CreationDate="2014-02-10T22:22:29.913" Score="17" ViewCount="1618" Body="&lt;p&gt;I've seen multiple videos online of evacuation slide tests and they all tend to be almost violent as they are very fast and loud, but I can't help thinking that it must put a lot of force on those seams when they inflate and along with that the material. Is there any &lt;strong&gt;limit to how many times these may be deployed&lt;/strong&gt; before they must be retired?&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2017-11-29T16:11:30.160" Title="Is there any limit to how many times an aircraft evacuation slide may be deployed?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1674" PostTypeId="2" ParentId="1673" CreationDate="2014-02-10T22:53:58.030" Score="18" Body="&lt;p&gt;The slide has to be removed from the aircraft completely (generally) and sent back to it's manufacturer to be inspected and repacked, but yes, it can be reused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gadling.com/2010/08/16/ask-gadling-does-it-really-cost-25-000-to-repack-an-airplane-e/&quot;&gt;This article talks about it in more detail.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a far as &quot;how many times&quot;, I would assume until it breaks ;).  Though honestly, I doubt a slide would ever be deployed more than once, maybe twice in it's life span.  &lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-02-10T22:53:58.030" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1675" PostTypeId="2" ParentId="1672" CreationDate="2014-02-10T23:24:09.247" Score="11" Body="&lt;p&gt;The most relevant data I could find was located &lt;a href=&quot;http://www.ncbi.nlm.nih.gov/pubmed/9016748&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, in a study on &quot;In-flight cabin smoke control&quot;. In the abstract, they stated that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tests on a Boeing 757, modified to allow smoke venting out through the top of the cabin, showed that the buoyant smoke front moved at 0.46m/s (1.5ft/sec) with and 0.27m/sec (0.9ft/sec) against, the axial ventilation airflow. Flight tests in a modified Boeing 727 showed that a ceiling level counterflow of about 0.55m/sec (1.8ft/sec) was required to arrest the forward movement of buoyant smoke. A design goal of 0.61m/s (2ft/sec) axial cabin flow would require a flow rate of 99m3/min (3500ft^3/min) in a furnished Boeing 757. The current maximum fresh air cabin ventilation flow is 78m^3/min (2756 ft^3/min).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In short, during &lt;em&gt;continuous generation&lt;/em&gt; of smoke, cabin air will not be recirculated quickly enough to stop smoke from filling the cabin; however, if the smoke production is temporary, then it should dissipate quickly (time of course depends on the size of the cabin and the amount of smoke produced).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On page 2 of this &lt;a href=&quot;https://engineering.purdue.edu/~yanchen/paper/2007-3.pdf&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt;, a discussion of airflow occurs and contained this image, showing circulation patterns on wide-body airliners. A linked study on that same page noted that &lt;code&gt;an under-floor displacement air distribution system [like the commonly used type picture below] can provide a much better air quality than a mixing air distribution system&lt;/code&gt;. The paper goes on to provide more diagrams of airflow and comparisons of various effectiveness if you're interested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mL3OS.png&quot; alt=&quot;Aircraft Circulation Patterns&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has a fairly detailed summary of their cabin airflow &lt;a href=&quot;http://www.boeing.com/boeing/commercial/cabinair/index.page&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. It says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Inside the cabin, the air flows in a generally circular patterns and exits through floor grilles on either side of the cabin and on airplanes with overhead recirculation, the air may exit through the overhead. The exiting air goes below the cabin floor into the lower lobe of the fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So at least on most Boeing planes, air exits at your feet, though it &lt;em&gt;can&lt;/em&gt; exit at the ceiling. Airbus also has a page &lt;a href=&quot;http://www.airbus.com/innovation/well-being/inside/atmosphere/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, but with much less detail. Airbus claims a complete recirculation every 2 to 3 minutes, while Boeing merely states airflow is continuous. The article linked below says in general, airplane recirculation occurs aproximately 20 circulations per hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;a href=&quot;http://www.nbcnews.com/id/34708785/ns/travel-travel_tips/t/airplane-air-not-bad-you-think/&quot; rel=&quot;noreferrer&quot;&gt;NBC article&lt;/a&gt; on cabin air states that to pick up a &lt;em&gt;sickness&lt;/em&gt;, you need to be close, &lt;code&gt;usually within two rows&lt;/code&gt;. The article goes on to say that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft is divided into ventilation segments of three to seven rows; you share air only with passengers in your segment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So presumably if there were smoke, it would be captured in a small area were it not too pervasive.&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-02-10T23:24:09.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1676" PostTypeId="1" AcceptedAnswerId="1677" CreationDate="2014-02-11T03:36:59.470" Score="20" ViewCount="20175" Body="&lt;p&gt;I've read a lot of NTSB crash reports regarding small, GA aircraft (just trying to figure out what went wrong and what to avoid.)  There seem to be a lot of reports that talk about &quot;low altitude high speed stalls&quot; (accelerated stall) happening on approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is an accelerated stall, and how is it created?  What is the best way to avoid one?  As they seem to cause a lot of GA accidents...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="69" LastEditDate="2014-08-05T11:41:00.043" LastActivityDate="2014-08-05T11:41:00.043" Title="Accelerated Stall, what is it, how do you prevent it?" Tags="&lt;general-aviation&gt;&lt;stall&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1677" PostTypeId="2" ParentId="1676" CreationDate="2014-02-11T04:24:07.903" Score="22" Body="&lt;h1&gt;Short Version&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;An accelerated stall is a stall that occurs at an airspeed higher than normal due to a higher load factor (g loading).&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Longer Version&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;When an aircraft is in a bank or when pulling back on the yoke quickly, the wing has to create additional lift to support the aircraft since the load factor has increased.  This increases the angle of attack beyond the critical angle of attack (the point where the wings can no longer produce enough lift to support the airplane) and the airplane will stall even though it is above the normal stall speed for the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JRuQl.png&quot; alt=&quot;Load Factor Explained&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Example&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Let's say that we are flying an airplane that has a &quot;normal&quot; stall speed of 60 KIAS.  If we start a 60 degree banked turn, this will increase the load factor on the airplane by two (2g) and will increase our stall speed by 41% to 85 KIAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lW1M0.gif&quot; alt=&quot;Load Factor Chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fairly common cause of this type of accident is when a pilot overshoots the runway centerline during the turn from base to final and steepens the bank angle in order to &quot;turn faster&quot; to get back on final.  Because the stall speed goes up, they can stall the airplane even though they normally never even come close at their current airspeed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, they should have just maintained the current bank angle that they had (instead of steepening it) and continued the turn back to re-intercept final using normal maneuvers.  If that couldn't be done in the amount of altitude/distance available, then simply go around and come back to try again (while making the proper wind correction in the turns this time).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-08-05T11:38:53.087" LastActivityDate="2014-08-05T11:38:53.087" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="1678" PostTypeId="2" ParentId="1653" CreationDate="2014-02-11T06:39:13.380" Score="5" Body="&lt;p&gt;Best bet is that there was an issue with the artificial horizon. If it was on an older aircraft without a glass cockpit, the gyro or its gimbal was probably broken causing the face to 'float' around or just stick at an odd angle. Then it was then communicated poorly to you by someone. Other than that I have never heard of a &quot;floating horizon&quot; and a google search doesn't yield any results either.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-11T06:39:13.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1679" PostTypeId="1" AcceptedAnswerId="1681" CreationDate="2014-02-11T12:55:33.290" Score="7" ViewCount="2742" Body="&lt;p&gt;I've seen on numerous different constant-speed propeller aircraft and different pilots using different RPMs during the cruise phase on a propeller aircraft. What dictates the RPM used during normal cruise operations, and why is that the case? Often there are multiple possible throttle/RPM combinations that deliver the same power, so where would you pick one or the other?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="1696" LastEditDate="2014-04-08T19:55:17.420" LastActivityDate="2014-04-08T19:55:17.420" Title="What dictates the prop RPM used during cruise?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;constant-speed-propeller&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1680" PostTypeId="2" ParentId="1679" CreationDate="2014-02-11T13:37:30.123" Score="8" Body="&lt;p&gt;The POH has performance tables (random example: &lt;a href=&quot;http://www.avsim.com/pages/0310/Carenado/Manual5.jpg&quot;&gt;http://www.avsim.com/pages/0310/Carenado/Manual5.jpg&lt;/a&gt;) showing fuel burn, true air speed, and %hp, for a given altitude, RPM, and manifold pressure. The pilot selects a performance configuration based primarily on what speed they wish to cruise at, which in turn determines how much fuel they're going to use. Different pilots differ in how much speed they want to achieve, making things somewhat a matter of opinion, but regardless of selection it's standard that the more you pull from the engine, the more harm you do to the engine. Personally, I tend to aim for 65% to 75% maximum horsepower in order to neither overtax my engine, nor use more fuel than is needed.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-02-11T13:37:30.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1681" PostTypeId="2" ParentId="1679" CreationDate="2014-02-11T14:39:20.030" Score="13" Body="&lt;p&gt;&quot;Dictate&quot; is the wrong word.  Within the ranges listed in the POH, the pilot may select rpm/MP settings as he pleases to meet other criteria.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Charles Lindbergh instructed many WWII pilots in a technique to extend range, by flying with low rpm and high manifold pressure.  This extended range by reducing the &quot;pumping losses&quot; required to maintain low manifold pressure.  Over long distances this technique did extend range considerably.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, lower rpm reduces noise - remember that the propeller is the largest contributor to a propeller-driven plane's noise signature.  This is important in the terminal environment where the noise can affect the ground, but it also affects in-cockpit noise regardless of altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This answer does not contradict the former answer, but it extends it to point out that there are other important factors that the pilot should consider in selection of engine operation parameters.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-02-11T16:43:10.450" LastActivityDate="2014-02-11T16:43:10.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1682" PostTypeId="1" AcceptedAnswerId="1683" CreationDate="2014-02-11T16:53:03.937" Score="14" ViewCount="2063" Body="&lt;p&gt;With all the shiny new glass cockpits it would seem that the days of the spinning mechanical gyro (and associated tumbling due to gimbal lock) should be over: Sparing everyone the &lt;a href=&quot;http://is.muni.cz/th/256569/fi_m/Masters_thesis.pdf&quot;&gt;boring math&lt;/a&gt; it should suffice to say that solid-state gyros can be engineered and built in such a way that gimbal lock is impossible, but I'm not certain that's how they're actually designed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do modern AHRS systems with solid-state gyros (or replacement electronic horizons like &lt;a href=&quot;http://www.kellymfg.com/images/RCA2600%20information.pdf&quot;&gt;the RC Allen 2600 series&lt;/a&gt;) still suffer from gimbal lock, or do they provide true 3-dimensional freedom?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested primarily in answers from a light General Aviation standpoint, but answers about electronic gyros on commuter and transport category aircraft would be interesting too.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-02-11T17:06:39.237" LastActivityDate="2015-09-20T03:10:28.840" Title="Are solid-state attitude indicators subject to gimbal lock?" Tags="&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1683" PostTypeId="2" ParentId="1682" CreationDate="2014-02-11T17:52:15.643" Score="10" Body="&lt;p&gt;AHRS cannot suffer from gimbal lock (as there are no gimbals that can share axes):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Conventional gyros are also susceptible to gimbal lock under certain conditions. The AHRS is an all-attitude system and is free from such problems. — &lt;em&gt;from &lt;a href=&quot;http://goo.gl/1Y3Fkj&quot;&gt;A Layman's Guide to AHRS&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That said, AHRS systems can still be tumbled - I know that for a while an air show routine was flown in a (then) Columbia 400 with G1000; the pilot remarked that the system Xed out only briefly while executing inverted maneuvers. In comparison, the Avidyne AHRS at the time required a full 2+ minutes of straight and level flight before resetting itself.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-02-11T17:52:15.643" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1684" PostTypeId="1" CreationDate="2014-02-11T21:39:56.927" Score="15" ViewCount="17532" Body="&lt;p&gt;When is an aircraft required to have a Cockpit Voice Recorder or a Flight Data Recorder?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="22726" LastEditDate="2019-05-27T02:55:09.447" LastActivityDate="2019-05-27T02:55:09.447" Title="Which aircraft are required to have a black box?" Tags="&lt;faa-regulations&gt;&lt;equipment&gt;&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1685" PostTypeId="2" ParentId="1684" CreationDate="2014-02-11T22:45:47.037" Score="16" Body="&lt;p&gt;&lt;strong&gt;Cockpit Voice Recorders&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Required for:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;large 4-engined turbine-powered planes&lt;/li&gt;&#xA;&lt;li&gt;large 4-engined pressurized planes&lt;/li&gt;&#xA;&lt;li&gt;multiengined turbine-powered planes seating 10+ passengers&lt;/li&gt;&#xA;&lt;li&gt;multiengined turbine-powered rotorcraft seating 20+ passengers&lt;/li&gt;&#xA;&lt;li&gt;multiengined turbine-powered planes and rotorcraft seating 6+ passengers &lt;em&gt;and&lt;/em&gt; requiring two pilots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Relevant regulations: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1b970fdf000773a59ac729b8b778ff13&amp;amp;node=14:3.0.1.1.7.11.2.45&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 121.359&lt;/a&gt;, &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/125.227&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 125.227&lt;/a&gt;, &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/135.151&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.151&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;121.359(d)&lt;/strong&gt; No person may operate a multiengine, turbine-powered airplane having a passenger seat configuration of 10-19 seats unless it is equipped with an approved cockpit voice recorder&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;125.227(a)&lt;/strong&gt; No certificate holder may operate a large turbine engine powered airplane or a large pressurized airplane with four reciprocating engines unless an approved cockpit voice recorder is installed in that airplane and is operated continuously from the start of the use of the checklist (before starting engines for the purpose of flight) to completion of the final checklist at the termination of the flight.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;135.151(a)&lt;/strong&gt; No person may operate a multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of six or more and for which two pilots are required by certification or operating rules unless it is equipped with an approved cockpit voice recorder&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;135.151(b)&lt;/strong&gt; No person may operate a multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of 20 or more seats unless it is equipped with an approved cockpit voice recorder&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Flight Data Recorders&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Required for:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Multiengine turbine-powered airplanes or rotorcraft seating 10+ passengers&lt;/li&gt;&#xA;&lt;li&gt;Multiengine turbine-powered airplanes or rotorcraft seating 6+ passengers &lt;em&gt;and&lt;/em&gt; requiring two pilots&lt;/li&gt;&#xA;&lt;li&gt;Large airplanes meant for use either over 25,000 feet&lt;/li&gt;&#xA;&lt;li&gt;Large turbine-powered airplanes&lt;/li&gt;&#xA;&lt;li&gt;Turbine-powered transport category planes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Relevant regulations: &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/91.609&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.609&lt;/a&gt;, &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/121.343&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 121.343&lt;/a&gt;, &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/121.344&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 121.344&lt;/a&gt;,&#xA;&lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/135.152&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.152&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;91.609(c)(1)&lt;/strong&gt; No person may operate a U.S. civil registered, multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration, excluding any pilot seats of 10 or more that has been manufactured after October 11, 1991, unless it is equipped with one or more approved flight recorders that utilize a digital method of recording and storing data and a method of readily retrieving that data from the storage medium, that are capable of recording the data specified in appendix E to this part, for an airplane, or appendix F to this part, for a rotorcraft, of this part within the range, accuracy, and recording interval specified, and that are capable of retaining no less than 8 hours of aircraft operation.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;91.609(e)&lt;/strong&gt; Unless otherwise authorized by the Administrator, after October 11, 1991, no person may operate a U.S. civil registered multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of six passengers or more and for which two pilots are required by type certification or operating rule unless it is equipped with an approved cockpit voice recorder that: &lt;em&gt;(1)&lt;/em&gt; Is installed in compliance with § 23.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); § 25.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); § 27.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); or § 29.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g) of this chapter, as applicable; and &lt;em&gt;(2)&lt;/em&gt; Is operated continuously from the use of the checklist before the flight to completion of the final checklist at the end of the flight.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;121.343(b)&lt;/strong&gt; No person may operate a large airplane type certificated up to and including September 30, 1969, for operations above 25,000 feet altitude, or a turbine-engine powered airplane certificated before the same date, unless it is equipped before May 26, 1989 with one or more approved flight recorders that utilize a digital method of recording and storing data and a method of readily retrieving that data from the storage medium.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;121.344(a)&lt;/strong&gt; Except as provided in paragraph (l) of this section, no person may operate under this part a turbine-engine-powered transport category airplane unless it is equipped with one or more approved flight recorders that use a digital method of recording and storing data and a method of readily retrieving that data from the storage medium.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Exceptions: &lt;code&gt;For aircraft manufactured before August 18, 1997, the following aircraft types need not comply with this section: Bell 212, Bell 214ST, Bell 412, Bell 412SP, Boeing Chinook (BV-234), Boeing/Kawasaki Vertol 107 (BV/KV-107-II), deHavilland DHC-6, Eurocopter Puma 330J, Sikorsky 58, Sikorsky 61N, Sikorsky 76A.&lt;/code&gt; [src: &lt;em&gt;14 CFR 135.152(k)&lt;/em&gt;]&lt;/p&gt;&#xA;&lt;p&gt;Additionally, the NBAA has &lt;a href=&quot;http://www.nbaa.org/ops/cns/cvr-fdr/&quot; rel=&quot;noreferrer&quot;&gt;links&lt;/a&gt; to summaries, but I do not have an account with them and was unable to retrieve the data.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-12T00:56:47.633" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1686" PostTypeId="2" ParentId="1572" CreationDate="2014-02-11T23:12:50.833" Score="0" Body="&lt;p&gt;In general, FAR Part 61, section 55a,b outlines specific requirements for those designated as Second-in-command of Aircraft requiring more than one pilot.  Section b probably covers the specific training you're curious about. See also parts 121, 125, and 135 for more specific requirements.&lt;/p&gt;&#xA;" OwnerUserId="728" LastActivityDate="2014-02-11T23:12:50.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1687" PostTypeId="1" AcceptedAnswerId="2015" CreationDate="2014-02-12T00:14:47.883" Score="8" ViewCount="322" Body="&lt;p&gt;Where can I find nice flutter animations/videos (other than &lt;em&gt;YouTube&lt;/em&gt;) to add to a presentation without violating Copyright regulations ? It can either be for wings as well as blade arrays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are you aware of any &lt;em&gt;OpenSource&lt;/em&gt; database on this topic ? &lt;/p&gt;&#xA;" OwnerUserId="201" LastEditorUserId="1696" LastEditDate="2015-02-12T22:30:58.837" LastActivityDate="2019-09-25T13:04:59.227" Title="Where can I find nice animations of flutter?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;flutter&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2019-09-25T17:14:06.527" ContentLicense="CC BY-SA 3.0" />
  <row Id="1689" PostTypeId="1" AcceptedAnswerId="1691" CreationDate="2014-02-12T02:48:38.890" Score="17" ViewCount="13575" Body="&lt;p&gt;Air Force One is obviously a big deal.  We close terminals and implement other seemingly crazy safeguards against terrorist attacks while the president is en-route to an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does ATC protect the president whilst in the air?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I have heard of TFRs for &quot;VIP in the area&quot; reasons &amp;mdash; is that for AF1?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I am guessing that the aircraft identification is blocked, but wouldn't they still need to have the transponder on for TCAS?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Specifically, the Wikipedia page on &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_force_one&quot;&gt;Air Force One&lt;/a&gt; has the following quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air traffic controllers gave Air Force One an ominous warning that a passenger jet was close to Air Force One and was unresponsive to calls. &quot;As we got over Gainesville, Fla., we got the word from Jacksonville Center. They said, 'Air Force One you have traffic behind you and basically above you that is descending into you, we are not in contact with them – they have shut their responder off.' And at that time it kind of led us to believe maybe someone was coming into us in Sarasota, they saw us take off, they just stayed high and are following us at this point. We had no idea what the capabilities of the terrorists were at that point.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does having the transponder on just paint a huge target on the radar for terrorists?&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="97" LastEditDate="2014-02-23T10:01:42.423" LastActivityDate="2018-08-29T18:42:56.040" Title="How does ATC protect Air Force One?" Tags="&lt;air-traffic-control&gt;&lt;terrorism&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1691" PostTypeId="2" ParentId="1689" CreationDate="2014-02-12T04:14:23.973" Score="19" Body="&lt;p&gt;Whenever Air Force 1 takes off or lands, the FAA establishes a 'Temporary Flight Restriction'.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially this is a big 'upside down wedding cake' of airspace in which Air Traffic Control exercises very tight control of any aircraft operating in the TFR.  Any traffic entering the TFR without prior approval, or any aircraft deviating from ATC instructions will be intercepted by military aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When President Obama takes a bus trip the FAA establishes a TFR over the bus, that moves so as to stay over the bus as he rolls along!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has a good article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Temporary_flight_restriction#Temporary_flight_restrictions&quot;&gt;TFRs&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="534" LastEditorUserId="97" LastEditDate="2014-02-23T10:05:35.417" LastActivityDate="2014-02-23T10:05:35.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1692" PostTypeId="1" AcceptedAnswerId="1695" CreationDate="2014-02-12T05:18:16.147" Score="7" ViewCount="1813" Body="&lt;p&gt;While looking over a tutorial on how to operate the Garmin GNS430, I couldn't find any info on how the device would report a degraded or low accuracy signal. What are the accuracy requirements for aviation GPS navigation systems and how are they required to alert a user in the case of a reduced accuracy situation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not specifically asking about RAIM here, as I believe that is mostly designed to identify a malfunctioning satellite or compromised signal. An example scenario would be some atmospheric condition that reduces positional accuracy to 1/4 mile or less.&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="81" LastEditDate="2014-02-12T06:14:33.243" LastActivityDate="2014-04-18T03:11:15.280" Title="How do aviation GPS navigation systems report GPS accuracy?" Tags="&lt;avionics&gt;&lt;gnss&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1693" PostTypeId="2" ParentId="1659" CreationDate="2014-02-12T05:24:09.360" Score="14" Body="&lt;p&gt;A few items just to add to the background info:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Large aircraft aren't just interested in being within the envelope, but also want to be close to an optimal c.g. location. For the 747-100, -200, -400 a zero fuel weight c.g. of 26.6 percent of the mean aerodynamic chord is the usual aiming point. This is done to minimize fuel burn while still staying within limits as fuel is burnt.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Large aircraft may also require different operating procedures when the c.g. is within certain parts of the c.g. envelope. The one that occurs to me offhand is the requirement for using a low-gross-weight-aft-cg takeoff procedure for 747s. There's also a restricted forward c.g. limit on the 747 when an operator has elected to use increased aft c.g. loading limits.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As your airspeed increases, a c.g. close to the forward or aft limits becomes less critical because the tail plane has more authority.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-12T05:24:09.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1694" PostTypeId="2" ParentId="1572" CreationDate="2014-02-12T05:29:20.567" Score="3" Body="&lt;p&gt;Don't know if the same rules still apply, but back in the 70s and 80s I used to fly legally as the second pilot on corporate jets with just a commercial license with IFR and multi-engine ratings. At the time I had no type ratings.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-12T05:29:20.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1695" PostTypeId="2" ParentId="1692" CreationDate="2014-02-12T08:05:04.887" Score="9" Body="&lt;p&gt;The required GPS accuracy depends mainly on the application. En-route requirements are more lenient than the accuracy requirements for non precision approaches. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS accuracy is the result of inaccuracies in the signal combined with a factor based on the geometry of the satellites. Within the receiver the position error is thus estimated by looking at&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The geometry of the satellites contributing to the position fix&lt;/li&gt;&#xA;&lt;li&gt;The estimated user equivalent ranging error (UERE) caused by various disturbances&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;From the geometry of the satellites, the (Geometric) Dilution of Precision (&lt;a href=&quot;http://en.wikipedia.org/wiki/Dilution_of_precision_%28GPS%29&quot; rel=&quot;noreferrer&quot; title=&quot;Dilution_of_precision&quot;&gt;DOP&lt;/a&gt;) is calculated. This is a number that expresses how the geometry of the satellites used to calculate the position influences the accuracy of the position solution. In an ideal situation, $DOP=1$, any value less than $4$ is considered good. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/36W4p.png&quot; alt=&quot;Simple illustration of DOP (a) good DOP smallest possible area of uncertainty, (b) degraded DOP, larger area of uncertainty&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DOP can be split up in three components, the horizontal (HDOP), the vertical (VDOP) and the time (TDOP). For horizontal position accuracy HDOP is used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second factor in the accuracy estimation is the User Equivalent Ranging Error (UERE). In the illustration above, this is the width of ranging bands. &#xA;UERE is composed of various factors:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ephemeris data - Errors in the transmitted location of the satellite&lt;/li&gt;&#xA;&lt;li&gt;Satellite clock - Errors in the transmitted clock.&lt;/li&gt;&#xA;&lt;li&gt;Ionosphere - Errors in pseudorange measurements caused by ionospheric effects&lt;/li&gt;&#xA;&lt;li&gt;Troposphere - Errors in pseudorange measurements caused by tropospheric effects&lt;/li&gt;&#xA;&lt;li&gt;Multipath - Errors caused by reflected signals entering the receiver antenna&lt;/li&gt;&#xA;&lt;li&gt;Receiver- Errors in the receiver's measurement of range caused by various internal factors.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The effect of the ephemeris data error is in the order of 2 meters (standard deviation). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accuracy of the satellite clock used to be intentionally degraded under the Selective Availability programme. SA was turned of in May 2000, drastically improving the GPS accuracy. Receivers developed before that date are unaware of this change and will estimate a worse accuracy than they actually achieve. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/G8f0u.png&quot; alt=&quot;Selective Availability turned off&quot;&gt;. The residual clock error after SA was turned of is equivalent to about 2.5 meters (standard deviation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS signal includes parameters for an ionospheric model which can be used to correct ionospheric effects. The residual error cause by signal delay in the ionosphere is in the order of 5 meter (standard deviation).  It is the most significant contribution to the UERE. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tropospheric effects are much less than the ionospheric effect. The effect is about 0.5 m (standard deviation). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multipath effects (caused by reflections of signals) are very much depending on the environment. In a city the effects are worse than in the air. For airborne applications multipath can be cause by reflections of the signal from the wings. The effect is very limited. On the airport surface there can be significant effects especially near buildings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Receiver errors caused by unstable oscillators (thermal noise), quantization and rounding errors, software errors etc. This contribution can be reduced by improving the design of the antenna and receiver; which all comes at cost. &#xA;Let's estimate the contributions to UERE about 3 meters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The UERE is the root mean square of all these contributions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$UERE=\sqrt{2^2+2.5^2+5^2+0.5^2+1^2+3^2}\approx6.75meters$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 95% accuracy is then estimated by $2\times{UERE}\times{HDOP}$. For a HDOP of $2$, the position would be estimated to be within 27 meters 95% of the time. Typical accuracy is better, because the UERE factors are estimated quite conservatively. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Augmentation systems such as WAAS and GBAS can improve the GPS accuracy by sending correction signals. The GNS 430 (without the 'W') does not use these signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the DOP is greater than $4$, the GNS 430 will display a message &quot;Degraded accuracy&quot;. You can find the DOP on the Satellite status page. This page also shows the estimated position error. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that all the calculations to estimate the position error assume that GPS is working as it should, i.e. a fault free condition. Faults can occur in the satellites, in the transmission of data to the receiver and in the receiver itself. Fault detection is part of the RAIM function.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="97" LastEditDate="2014-04-18T03:11:15.280" LastActivityDate="2014-04-18T03:11:15.280" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1696" PostTypeId="1" AcceptedAnswerId="1721" CreationDate="2014-02-12T10:08:45.280" Score="18" ViewCount="12788" Body="&lt;p&gt;I know that it's possible for military aircraft to &quot;intercept&quot; a civilian or foreign aircraft (and I'm well aware of the US interception procedures), but why would they be  doing it in the first place? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does it actually prevent from occurring?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can't remotely control the aircraft, so is there anything that they can do once they intercept it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sItbi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="700" LastEditDate="2014-10-29T20:07:18.007" LastActivityDate="2014-10-29T20:07:18.007" Title="What's the point of intercepting an aircraft?" Tags="&lt;safety&gt;&lt;military&gt;&lt;flight-interception&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1697" PostTypeId="2" ParentId="1696" CreationDate="2014-02-12T10:25:48.840" Score="11" Body="&lt;p&gt;As far as I know, interception of civilian aircraft is done to assess a situation where the safe status of a flight is uncertain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Vueling A320 &lt;a href=&quot;http://www.youtube.com/watch?v=zmvh2wP1BHs&quot;&gt;got intercepted&lt;/a&gt; some time ago when the French ATC weren't able to communicate with the pilot. The same airline some time later got &lt;a href=&quot;http://avherald.com/h?article=4550b86c&quot;&gt;another interception by the Dutch&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intercepting the aircraft and watching the situation inside the cockpit and/or the cabin can help to assess whether there is a serious situation developing (and further actions can be taken, such as alerting emergency services on the ground, monitoring the flight path, continuing the interception procedure to try to improve the situation). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not about &lt;em&gt;piloting&lt;/em&gt; the intercepted aircraft, but about assessing the status of the flight. I think it's just a matter of gaining some time if a hijacking occurs.&lt;/p&gt;&#xA;" OwnerUserId="424" LastEditorUserId="424" LastEditDate="2014-02-13T06:45:42.380" LastActivityDate="2014-02-13T06:45:42.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1698" PostTypeId="2" ParentId="1696" CreationDate="2014-02-12T10:28:02.017" Score="16" Body="&lt;p&gt;Military interception usually happens after failure to make the aircraft comply by other means (such as radio, light signals, flares). So, first and foremost it is one way to do visual communications, which is usually hard for the pilot to miss. The messages for follow (wide level turn), land (low pass, landing gear extended), and continue on course (climbing turn) are well established (possibly even internationally?) and all pilots should know them, and are probably enough to defuse most situations. Not to mention that you should try to establish radio communications on 121.5 if you're being intercepted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd wager a guess that the most common cause for interception is that a pilot has strayed into restricted airspace without talking to anyone on the radio, without any malicious intent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot ignores the messages, there's always the option of using force, if the risk to occupants and collateral on the ground is acceptable.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-02-12T10:33:49.880" LastActivityDate="2014-02-12T10:33:49.880" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1699" PostTypeId="1" CreationDate="2014-02-12T12:53:32.977" Score="7" ViewCount="9230" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;SID=257acc4699ee7253af775fc7e9492e51&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.1.1.34&quot;&gt;14 CFR 61.55&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) A person may receive a second-in-command pilot type rating for an&#xA;  aircraft after satisfactorily completing the second-in-command&#xA;  familiarization training requirements under paragraph (b) of this&#xA;  section in that type of aircraft provided the training was completed&#xA;  within the 12 calendar months before the month of application for the&#xA;  SIC pilot type rating. The person must comply with the following&#xA;  application and pilot certification procedures:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) The applicant must appear in person at a FAA Flight Standards&#xA;  District Office or to an Examiner with his or her logbook/training&#xA;  records and with the completed and signed FAA Form 8710-1.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) There is no practical test required for the issuance of the “SIC&#xA;  Privileges Only” pilot type rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What exactly is an SIC type rating used for and how can someone get a &quot;type rating&quot; without any kind of practical test?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-10-01T17:57:46.807" Title="What is an SIC type rating?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;&lt;type-ratings&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1700" PostTypeId="1" AcceptedAnswerId="1705" CreationDate="2014-02-12T12:58:18.887" Score="12" ViewCount="2470" Body="&lt;p&gt;I hear a lot about CRM these days (it seems to be a buzz word). It is related to safety, but what exactly is it?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I know, it also applies to single pilot flights (even in a Cessna 150!), but where is the &quot;crew&quot; that is being managed in this case and how does it improve safety?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2017-04-27T19:14:29.187" LastActivityDate="2017-04-27T19:14:29.187" Title="What is Crew Resource management (CRM)?" Tags="&lt;safety&gt;&lt;crew-resource-management&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1701" PostTypeId="2" ParentId="1700" CreationDate="2014-02-12T13:58:10.547" Score="0" Body="&lt;p&gt;In Europe:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, Crew Resource Management or Cockpit Resource Management training is only needed for commercial/airline flights where multi-pilot aircrafts are flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's basically Multi Crew Co-operation (MCC) training (plus the communication aspect) with the purpose of increasing the efficiency of communication, coordination, decision-making and leadership in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end it breaks down to efficient pilot communication, efficient distribution of cockpit tasks and &quot;inter-pilot-double-checks&quot; (meaning a pilot checking the other pilot actions and vice-versa).&lt;/p&gt;&#xA;" OwnerUserId="854" LastEditorUserId="854" LastEditDate="2014-02-13T09:47:36.823" LastActivityDate="2014-02-13T09:47:36.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1702" PostTypeId="2" ParentId="1700" CreationDate="2014-02-12T16:14:40.877" Score="8" Body="&lt;p&gt;CRM is not just crew anymore - it's now typically referred to as &amp;quot;&lt;em&gt;Cockpit&lt;/em&gt; Resource Management&amp;quot; (or in some cases, when no crew is present, as &amp;quot;Single-Pilot Resource Management&amp;quot;) and it's something the FAA emphasizes on &lt;strong&gt;all&lt;/strong&gt; checkrides.&lt;/p&gt;&#xA;&lt;p&gt;CRM includes all resources available to any pilot. In a typical light GA aircraft this means checklists, instruments, gauges, radios, and nav. However, ATC is a resource, especially during abnormal or emergency situations. So is FSS, Unicom, or even other aircraft nearby (think relaying an IFR cancellation etc).&lt;/p&gt;&#xA;&lt;p&gt;In a large aircraft, CRM obviously includes your flight and cabin crew, plus other airline or corporate perks like dispatch.&lt;/p&gt;&#xA;&lt;p&gt;The safety improvements come from knowing when to offload work or call on systems or people for assistance. Even a non-pilot passenger can be a huge help in spotting other aircraft, tuning radios, rummaging around for your spare pen... that's all CRM and lets the pilot focus on flying.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/#pilots&quot; rel=&quot;noreferrer&quot;&gt;Private Pilot PTS (FAA-S-8081-14B)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;Special Emphasis Areas&lt;/h3&gt;&#xA;&lt;p&gt;Examiners shall place special emphasis upon areas of aircraft operations considered critical to flight safety. Among these are:&lt;/p&gt;&#xA;&lt;p&gt; 15. Single-Pilot Resource Management (SRM), and&lt;br/&gt;&#xA; 16. Other areas deemed appropriate to any phase of the&#xA;practical test.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-12T16:35:40.193" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1703" PostTypeId="1" AcceptedAnswerId="1706" CreationDate="2014-02-12T16:26:08.873" Score="21" ViewCount="4715" Body="&lt;p&gt;I read that an ILS is a precision approach system. It provides a final approach with precision in both horizontal and vertical guidance to the runways. But I don't know &lt;em&gt;how&lt;/em&gt; precise it is because there were a number of accidents related to landing operations.&lt;/p&gt;&#xA;" OwnerUserId="848" LastEditorUserId="69" LastEditDate="2014-02-12T22:34:32.327" LastActivityDate="2014-03-24T12:06:46.883" Title="How precise is an ILS (Instrument landing system)?" Tags="&lt;ils&gt;&lt;navaids&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1704" PostTypeId="2" ParentId="1699" CreationDate="2014-02-12T16:34:16.013" Score="3" Body="&lt;p&gt;It's an ICAO requirement, basically it's just official documentation showing that you've been trained and are  competent to act as SIC in a given airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO is an organization that standardizes regulations and procedures among the participating countries (close to 200 if I recall).  If you fly as SIC internationally you'll probably need an SIC type rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rating is almost the same as a PIC type rating, except the rejected takeoff and taxi requirements (and maybe some others) don't have to be met.  It's basically a formality for any airline first officer as they will have met all the requirements just by going through the airline's training.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-02-12T16:34:16.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1705" PostTypeId="2" ParentId="1700" CreationDate="2014-02-12T16:42:27.440" Score="9" Body="&lt;p&gt;CRM is about making use of all available resources to safely conduct a flight.  Pilots these days (even single pilot ops) have a wealth of resources available to them.  Anything you can see and anyone you can talk to is a resource, and CRM is about making efficient use of those resources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a light single you will have a subset of these resources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cockpit displays&lt;/li&gt;&#xA;&lt;li&gt;Charts&lt;/li&gt;&#xA;&lt;li&gt;Checklists&lt;/li&gt;&#xA;&lt;li&gt;ATC&lt;/li&gt;&#xA;&lt;li&gt;FSS&lt;/li&gt;&#xA;&lt;li&gt;Flight Watch (EFAS)&lt;/li&gt;&#xA;&lt;li&gt;Live Weather downlinks (e.g. XM satellite weather)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On a large transport aircraft these change a bit:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cockpit displays&lt;/li&gt;&#xA;&lt;li&gt;Charts&lt;/li&gt;&#xA;&lt;li&gt;Checklists&lt;/li&gt;&#xA;&lt;li&gt;ATC&lt;/li&gt;&#xA;&lt;li&gt;FSS&lt;/li&gt;&#xA;&lt;li&gt;EFAS&lt;/li&gt;&#xA;&lt;li&gt;Onboard RADAR&lt;/li&gt;&#xA;&lt;li&gt;The QRH (quick reference handbook)&lt;/li&gt;&#xA;&lt;li&gt;The FOM (flight operations manual)&lt;/li&gt;&#xA;&lt;li&gt;The other pilot(s)&lt;/li&gt;&#xA;&lt;li&gt;The cabin crew&lt;/li&gt;&#xA;&lt;li&gt;Passengers (Doctor in a medical emergency?  People helping in an evac?)&lt;/li&gt;&#xA;&lt;li&gt;Dispatch&lt;/li&gt;&#xA;&lt;li&gt;Medlink&lt;/li&gt;&#xA;&lt;li&gt;Company Ops&lt;/li&gt;&#xA;&lt;li&gt;For ground ops:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuellers&lt;/li&gt;&#xA;&lt;li&gt;Ramp personell&lt;/li&gt;&#xA;&lt;li&gt;Gate agents&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;More and more emphasis is placed on managing these resources as you move up the chain.  By the time you are taking your first 121 upgrade checkride, it is more about judgement and CRM than it is about the flying. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-12T16:50:33.250" LastActivityDate="2014-02-12T16:50:33.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1706" PostTypeId="2" ParentId="1703" CreationDate="2014-02-12T16:46:15.510" Score="20" Body="&lt;p&gt;The ILS is &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot;&gt;precise enough to allow landings in essentially zero visibility, including those performed by autoland&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The ground based bits&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The vertical range is 1.4° (0.7° above glideslope, 0.7° below) and the horizontal varies, but is a maximum of 6° wide. What this means in terms of how many feet or meters off the centerline an aircraft is varies depending on where the aircraft is on the approach, but it's generally correct to say that the closer an aircraft gets to the ILS antennae, the more precise the system is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specifications for a localizer antenna require that it be no less precise than ±10.5m - this is for a Cat I approach, and it gets correspondingly more precise as the category increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's always the risk of interference with the transmitters; as noted in the comments, accidents have been caused by airport vehicles parked in the ILS critical area, interfering with the signals, and as the equipment ages it can require recalibration.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The airborne bits&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It's possible for receivers to have issues that could affect precision; antennas can get loose connections or become covered in ice, while pilots might interpret indications incorrectly, misread reverse sensing, or &lt;a href=&quot;http://www.pprune.org/tech-log/358117-ils-capture-above-false-gs.html&quot;&gt;intercept a 'false glideslope' from above&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Regarding accidents&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;You're correct - there are many accidents related to landing operations. That said, you may be including those which weren't flying an ILS approach - it's hard to say since you aren't citing anything. Still, it's possible that there's confusion between &lt;strong&gt;navigation precision&lt;/strong&gt; and &lt;strong&gt;safety of flight&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many (not all) of landing accidents involving instrument approaches do center around human error rather than equipment failure; pilots tuning in the wrong frequency or incorrectly setting avionics and instruments (reversing the inbound course on an HSI causes reverse sensing, that sort of thing), or people on the ground screwing up.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-02-12T22:18:52.967" LastActivityDate="2014-02-12T22:18:52.967" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1707" PostTypeId="1" AcceptedAnswerId="2776" CreationDate="2014-02-12T17:29:21.087" Score="13" ViewCount="1261" Body="&lt;p&gt;When climbing or descending in a multi-crew cockpit, most SOP's require a verbal callout at 1,000 ft. prior to the assigned altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I typically hear different callouts by different people:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;One to go&quot;&lt;/li&gt;&#xA;&lt;li&gt;&quot;Six thousand for seven thousand&quot;&lt;/li&gt;&#xA;&lt;li&gt;&quot;Six thousand climbing seven thousand&quot;&lt;/li&gt;&#xA;&lt;li&gt;&quot;Six for seven&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is this just a personal preference kind of thing or is there an actual safety benefit to one or the other?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2015-04-21T15:24:03.383" LastActivityDate="2019-03-29T17:08:44.690" Title="How should the crew callout 1,000 ft. prior to assigned altitude?" Tags="&lt;safety&gt;&lt;phraseology&gt;&lt;sop&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1708" PostTypeId="2" ParentId="1238" CreationDate="2014-02-12T19:00:50.420" Score="1" Body="&lt;p&gt;Or, alternatively, the answer is that the tower has the same (local) operating hours no matter if it's DST or not, i.e., it's always 9-5 local.  However, since all hours are written in Zulu and the conversion to Zulu and local can change depending on if it's DST or not, this provides a quick shortcut to duplicating every entry's times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More than anything else, this is a cautionary note that one should never speak 'x Standard time' unless you mean it - just say 'x time' instead.&lt;/p&gt;&#xA;" OwnerUserId="162" LastActivityDate="2014-02-12T19:00:50.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1709" PostTypeId="2" ParentId="1703" CreationDate="2014-02-12T20:18:59.913" Score="10" Body="&lt;p&gt;ILS is can be very precise, but there are many factors that may compromise the precision. When all these factors are avoided, automatic landing with no visibility is reliably possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ILS installations are classified in three categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;CAT I: Category 1 allows for decision height (DH) no less than 200 ft (height, so above ground level).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ILS creates the signal by interference of different signals emitted by offset antennas. If one of them fails, but not the other, the signal may appear as perfectly centred to the instrument on board of the approaching aircraft with no way to tell that it does not actually work. Therefore pilots should cross-reference their position using other sources (DME, VOR, ADF, marker beacons).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a video about this kind of failure (describes an actual incident where the glide slope stopped working without indication, the crew noticed by cross-checking against DME and altitude, plus description of the failure), but I can't find it now.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CAT II: Category 2 allows for DH not less than 100 ft and allows using auto-land until touch-down. It needs to have far field monitoring that can detect incorrect or incomplete signal and the transmission system has to be doubled. It also needs to be somewhat more precisely aligned than CAT I.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CAT III: Category 3 allows auto-land including roll-out. It has subcategories IIIa that allows DH not less than 50 ft, IIIb that allows DH down to 0 ft (so effectively no DH) and visibility 75 m (otherwise the plane could not taxi off the runway as there is no guidance for taxiing; when there is, it will be called CAT IIIc). It has stricter limits on precision and monitoring than the CAT II.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Independent of the category, direct line of sight is needed. The signal is not affected by fog and precipitation, but is distorted by any obstacles. Aircraft or even small vehicle crossing the runway or taxiing in front of the transmitter will significantly distort the signal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's why each ILS CAT II and CAT III installation has ILS protected areas and to actually use auto-landing, special procedures need to be in effect that keep these areas clear. When they are not, incidents like &lt;a href=&quot;http://avherald.com/h?article=445873f3&quot;&gt;Singapore B773 at Munich on Nov 3rd 2011, runway excursion&lt;/a&gt; happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly attempting to auto-land on CAT I lead to accidents like &lt;a href=&quot;http://avherald.com/h?article=46e20f3a&quot;&gt;Air India A320 at Jaipur on Jan 5th 2014, runway excursion on emergency landing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-02-12T20:18:59.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1710" PostTypeId="2" ParentId="1699" CreationDate="2014-02-12T22:54:45.840" Score="1" Body="&lt;p&gt;Its a box to check to make ICAO happy if you want your operation to fly outside of the US.  For a 121 initial training program it literally is a checkbox -- you pass training and have an 8710 ready and an APD gives you the rating.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its a formalization of knowing the airplane well enough to operate it in normal and abnormal conditions without the rigor of the PIC type (e.g. as an FO you do the oral exam with your sim partner and as Lnafziger points out, you don't cover the PTS for the SIC type like you do for a PIC type).&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-13T19:33:07.023" LastActivityDate="2014-02-13T19:33:07.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1711" PostTypeId="2" ParentId="1703" CreationDate="2014-02-13T02:18:09.023" Score="1" Body="&lt;p&gt;Quoting &lt;a href=&quot;https://aviation.stackexchange.com/questions/1703/how-precise-is-an-ils-instrument-landing-system/1706#1706&quot;&gt;egid&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The vertical range is 1.4° (0.7° above glideslope, 0.7° below) and&#xA;  the horizontal varies, but is a maximum of 6° wide. What this means in&#xA;  terms of how many feet or meters off the centerline an aircraft is&#xA;  varies depending on where the aircraft is on the approach, but it's&#xA;  generally correct to say that the closer an aircraft gets to the ILS&#xA;  antennae, the more precise the system is.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know of at least one reader who has a problem with this statement, so I'm only adding these comments for clarification.  EGID is correct.  Think of the localizer as a funnel ... the &quot;hopper&quot; end of the funnel catches more liquid when it is bigger and fans out wider ... but it ultimately leads to the same narrow downspout.  If the purpose of this funnel is to catch and direct more incoming liquid (aircraft) then it's doing no one favors to have too narrow of a hopper.  All funnels are very precise on the small end.  You want an ILS to be fairly forgiving for the reason that you may be intercepting it while blind and in the soup.&lt;/p&gt;&#xA;" OwnerUserId="699" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-03-24T12:06:46.883" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1712" PostTypeId="1" AcceptedAnswerId="1713" CreationDate="2014-02-13T05:22:00.020" Score="32" ViewCount="9467" Body="&lt;p&gt;When flying on a long-haul airliner flight in economy, often I find it very hard to fall asleep. However, when off cockpit duties, they still have to get rest so that they are able to control the aircraft without being exhausted and collapsing on the controls when they are on duty. Are there are any specific methods of helping pilots to gain the rest required on board an aircraft? Have there been any studies about the effectiveness of these?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="21827" LastEditDate="2017-12-30T09:47:01.937" LastActivityDate="2019-01-01T16:07:29.030" Title="How do pilots rest on long-haul flights?" Tags="&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1713" PostTypeId="2" ParentId="1712" CreationDate="2014-02-13T06:21:24.280" Score="27" Body="&lt;p&gt;Unlike passengers in economy who are trying to sleep in sitting position in seat that can be only partially reclined, the pilots sleep lying in a bed. Long range aircraft have a crew rest area. They are often above or below the main cabin and therefore low, not allowing standing up, but they always have beds or fully convertible chairs. The flight crew rest area is most commonly for 3 and separate cabin crew rest area for whatever is the usual number of flight attendants in given plane.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="3386" LastEditDate="2018-11-19T08:21:28.623" LastActivityDate="2018-11-19T08:21:28.623" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="1714" PostTypeId="2" ParentId="1712" CreationDate="2014-02-13T09:59:28.117" Score="32" Body="&lt;p&gt;Since a picture speaks for a thousand words...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are often called &quot;coffins&quot; or &quot;sarcophagus&quot; around here... (Portugal)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qeFYs.jpg&quot; alt=&quot;crew rest area&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Boeing/Boeing-777-240-LR/0908517&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="854" LastEditorUserId="8282" LastEditDate="2019-01-01T16:07:29.030" LastActivityDate="2019-01-01T16:07:29.030" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="1715" PostTypeId="1" AcceptedAnswerId="1716" CreationDate="2014-02-13T11:38:00.687" Score="9" ViewCount="163" Body="&lt;p&gt;In theory, the authority to approve an LSA manufacturer and design has the right to audit their testing and work. What I'm interested in how often does this happen in practice, and whether there have been any cases of violations found because of this. Is the system of trusting manufacturers to be honest with their paperwork working so far?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="19" LastEditDate="2017-03-20T16:15:52.910" LastActivityDate="2017-03-20T16:15:52.910" Title="Have there been instances where a LSA manufacturer has been audited?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1716" PostTypeId="2" ParentId="1715" CreationDate="2014-02-13T13:50:56.350" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.lama.bz/wp-content/uploads/2013/03/Internal-Audit-Outline-0612.pdf&quot; rel=&quot;noreferrer&quot;&gt;Per this letter&lt;/a&gt; it appears that manufacturers who make LSA compliant aircraft are subject to a sort of enforced self regulation.  Basically, they are required to audit themselves every year and are told that the FAA could come and inspect their facility at any given moment, with heavy fines if an inspection is failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of this each aircraft itself is inspected by a technician before it leaves the facility to make sure that each aircraft meets the standards.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.lama.bz/wp-content/uploads/2013/03/Internal-Audit-Outline-0612.pdf&quot; rel=&quot;noreferrer&quot;&gt;The entire process is explained in more detail here.&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did a bit of a search over a few of my favorite LSA news sites and I couldn't find any instances where an FAA inspection actually resulted in the proposed fines/punishments.  It seems that so far the semi-self-regulation model is working fairly well.  Well enough that, as Dan Johnson points out in that second article, it appears the FAA is considering using the same certification model for type aircraft as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarize, yes they are being audited, but by themselves.  It is also likely that outside bodies are auditing them as well, but nothing newsworthy seems to have come of any random inspections, so there is no mention of said audits.  I'm sure if somebody fails one, it will be big news.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-02-13T15:41:51.093" LastActivityDate="2014-02-13T15:41:51.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1717" PostTypeId="2" ParentId="1707" CreationDate="2014-02-13T15:54:16.723" Score="1" Body="&lt;p&gt;While I don't fly in a plane requiring more than one person, when there happens to be two pilots, such as one flying safety so the other can fly under the hood, I prefer the &quot;1,000 feet remaining&quot; or &quot;1,000 remaining&quot; call out.  I don't really have some scientific reason for it, but it just seems more logical to me and easier to interpret.  &lt;/p&gt;&#xA;" OwnerUserId="838" LastActivityDate="2014-02-13T15:54:16.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1718" PostTypeId="2" ParentId="1707" CreationDate="2014-02-13T15:59:00.523" Score="4" Body="&lt;p&gt;As far as I know, there are no published FAA guidelines on it.  An operator develops their SOP, and the FAA approves it, so whatever the SOP says is approved by the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ours is, &quot;one thousand to go,&quot; by the pilot flying, and then, &quot;nine thousand for ten thousand,&quot; responded by the pilot  monitoring.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-02-13T15:59:00.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1719" PostTypeId="2" ParentId="1696" CreationDate="2014-02-13T16:03:11.377" Score="5" Body="&lt;p&gt;One large part of the reason to intercept any aircraft is to visually confirm  the identity of the aircraft.  While every other method of communication is valid in establishing the identity, only &quot;eyes on&quot; can unequivocally confirm the tail number and registration of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="728" LastActivityDate="2014-02-13T16:03:11.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1720" PostTypeId="2" ParentId="1609" CreationDate="2014-02-13T17:49:20.830" Score="-7" Body="&lt;p&gt;I'm not even close to an expert. But here it goes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air like water is thick. Submarines are slower than boats. Jets are faster than boats. Automobiles are faster than boats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Space has no friction because there is no matter. But I think jets still work in space. Of course they need oxygen. Just like Superman doesn't need ground friction to run fast, while some other super heroes do. Which is why I find it unrealistic how a super heroes that need ground friction are able to run so fast and make sharp turns without doing serious damage to floors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'm guessing that being that the air is less thick up higher, that the easier it is to travel through. The jets don't depend on friction like propellers do. Superman doesn't need friction like Flash Gordon or Wonder Woman. So in space, Wonder Woman would be helpless because her propellers don't work while Superman's jets will work just fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course jet's need oxygen. So I'm not sure how all that works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And something I didn't think of was what was mentioned in another post. Sound needs air. So yeah. Sound can increase friction.&lt;/p&gt;&#xA;" OwnerUserId="866" LastActivityDate="2014-02-13T17:49:20.830" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1721" PostTypeId="2" ParentId="1696" CreationDate="2014-02-13T19:25:26.173" Score="15" Body="&lt;p&gt;The most common reason for interception is that an aircraft is not communicating with ATC and is somewhere that they aren't supposed to be.  Often times it turns out to be unintentional with the aircraft on a VFR flight (i.e. poor flight planning or deviating for weather) and straying into a restricted or prohibited area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these cases, the standard intercept signals (&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html#XiC212ROBE&quot;&gt;AIM 5-6-4&lt;/a&gt;) are designed to attract the pilot's attention and have them proceed out of the area.  In addition to the &quot;standard&quot; signals, they can also drop flares in front of the airplane to really get their attention if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cases where the airplane still doesn't respond &lt;strong&gt;and&lt;/strong&gt; the aircraft appears to be a threat to national security, the decision can be made by a few senior military and civilian officials to actually shoot down the aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For more detail, in the US section &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html&quot;&gt;5-6-2&lt;/a&gt; of the AIM gives the following reasons that a civil aircraft may be intercepted by a military aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-6-2. Interception Procedures&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a. General.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. In conjunction with the FAA, Air Defense Sectors monitor air traffic and could order an intercept in the interest of national&#xA;  security or defense. Intercepts during peacetime operations are vastly&#xA;  different than those conducted under increased states of readiness.&#xA;  The interceptors may be fighters or rotary wing aircraft. The reasons&#xA;  for aircraft intercept include, but are not limited to:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Identify an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Track an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Inspect an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Divert an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Establish communications with an aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Flightgear.org also has a good &lt;a href=&quot;http://wiki.flightgear.org/Aircraft_interception#Reasons_for_interception_in_real_life&quot;&gt;wiki on interception procedures&lt;/a&gt; that covers some of the common reasons that they are used (and includes all of the ones that I was going to include):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Reasons for interception in real life&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Civilian aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;While interception of civilian aircraft is a last resort, interception&#xA;  is often the only means available to identify an aircraft that have&#xA;  not filed a flight plan and/or have no transponder and can not be&#xA;  contacted. Apart from identification interception is as well often the&#xA;  only means to redirect an aircraft that is straying into limited&#xA;  airspace or is believed to be involved in illegal activities.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Identification&lt;/strong&gt;&lt;br&gt;&#xA;  Visual identification of aircraft that can not otherwise be identified.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Redirection&lt;/strong&gt;&lt;br&gt;&#xA;  An aircraft may be intercepted and through visual signals or radio communication on emergency channels be requested to&#xA;  change route and possibly to land at an specific airport if an aircraft &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;is straying away from a route,&lt;/li&gt;&#xA;  &lt;li&gt;are entering a danger, restricted or prohibited area,&lt;/li&gt;&#xA;  &lt;li&gt;are suspected to fly illegally or is smuggling goods or persons,&lt;/li&gt;&#xA;  &lt;li&gt;enters a countries airspace without permit an fails to follow instructions to leave the airspace or land at a specific airport,&lt;/li&gt;&#xA;  &lt;li&gt;enters a countries airspace at different positions or routes than permitted, or &lt;/li&gt;&#xA;  &lt;li&gt;is a hazard to other aircraft&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-13T19:33:32.567" LastActivityDate="2014-02-13T19:33:32.567" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1722" PostTypeId="1" AcceptedAnswerId="1727" CreationDate="2014-02-13T19:41:25.123" Score="14" ViewCount="43259" Body="&lt;p&gt;Under normal 2 pilot part 121 ops I could only be scheduled to fly 8 hours in a given day.  This is plenty for the routes we flew (longest leg around 4 hours) so I never encountered the rules for longer flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For flying beyond 8 hours -- long haul international ops -- what determines how many pilots must be on board?  Is only flight time taken into account or is the number of timezones crossed also a factor?  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2019-03-15T05:45:30.643" Title="How many pilots do long flights need?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1723" PostTypeId="1" AcceptedAnswerId="1724" CreationDate="2014-02-13T19:47:42.273" Score="9" ViewCount="14393" Body="&lt;p&gt;When frost adheres to the airplane or it is snowing, you need to make sure the airplane is clean when you depart.  You've probably seen the trucks spraying aircraft in the winter before departure, but what are the spraying it with?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know of at least 4 types of de-/anti-ice fluids but perhaps there are others.  What does each fluid consist of and what is its function?  How do I know if these fluids are available at an airport I plan to operate from?  Are there limits in how soon I must depart once fluid is applied?&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="609" LastEditDate="2014-04-08T19:49:02.723" LastActivityDate="2014-04-08T19:49:02.723" Title="What are the different kinds of de-ice fluid?" Tags="&lt;weather&gt;&lt;anti-ice&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1724" PostTypeId="2" ParentId="1723" CreationDate="2014-02-13T20:29:20.350" Score="8" Body="&lt;h1&gt;Fluid Types&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Deicing_fluid&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; contains a good summary of the different types of fluid:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Types&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Type I fluids have a low viscosity, and are considered &quot;unthickened&quot;. They provide only short term protection because they&#xA;  quickly flow off surfaces after use. They are typically sprayed on hot&#xA;  (130–180°F, 55-80°C) at high pressure to remove snow, ice, and frost.&#xA;  Usually they are dyed orange to aid in identification and application.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Type II fluids are pseudoplastic, which means they contain a polymeric thickening agent to prevent their immediate flow off&#xA;  aircraft surfaces. Typically the fluid film will remain in place until&#xA;  the aircraft attains 100 knots or so (almost 200 km/h), at which point&#xA;  the viscosity breaks down due to shear stress. The high speeds&#xA;  required for viscosity breakdown means that this type of fluid is&#xA;  useful only for larger aircraft. The use of type II fluids is&#xA;  diminishing in favour of type IV. Type II fluids are generally light&#xA;  yellow in color.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Type III fluids can be thought of as a compromise between type I and type II fluids. They are intended for use on slower aircraft, with&#xA;  a rotation speed of less than 100 knots. Type III fluids are generally&#xA;  light yellow in color.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Type IV fluids meet the same AMS standards as type II fluids, but they provide a longer holdover time. They are typically dyed green to&#xA;  aid in the application of a consistent layer of fluid.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Chemical Composition&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The main component of deicing fluid is usually propylene glycol or&#xA;  ethylene glycol. Other ingredients vary depending on the manufacturer,&#xA;  but the exact composition of a particular brand of fluid is generally&#xA;  held as confidential proprietary information.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Call ahead to the airport to see what kind of deice/anti-ice fluid that they have because each one is different.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Time Limits&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Every year, the FAA publishes tables which include information about how long the various deice fluids will provide protection under various weather conditions.  Here is an example table:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/t8JSa.jpg&quot; alt=&quot;Holdover Table&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this particular fluid (ABAX ECOWING AD-49 Type IV) we can lookup a specific example such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;-10 Degrees Celcius&lt;/li&gt;&#xA;&lt;li&gt;75% fluid and 25% water&lt;/li&gt;&#xA;&lt;li&gt;Light Snow&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This shows that the fluid will provide protection for 1:40 to 2:05. If you are delayed longer than that, you will need to deice again.  Since &lt;strong&gt;every&lt;/strong&gt; part of the aircraft needs to be protected, the timing starts when they first start spraying the aircraft.  Note that other types of fluid (particularly Type I fluids) have &lt;strong&gt;much&lt;/strong&gt; shorter holdover times than this, so be careful and make sure that you check!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Resources&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/media/FAA_2013-14_Holdover_Tables.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;OFFICIAL FAA HOLDOVER TIME TABLES WINTER 2013-2014&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23199&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 120-60B - Ground Deicing and Anti-icing Program&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-13T20:29:20.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1725" PostTypeId="1" CreationDate="2014-02-13T20:32:14.720" Score="8" ViewCount="20209" Body="&lt;p&gt;I constantly see regulations which refer to &quot;flag&quot; and &quot;supplemental&quot; operations.  For example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr121_main_02.tpl&quot;&gt;14 CFR 121 — OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Subpart Q—FLIGHT TIME LIMITATIONS AND REST REQUIREMENTS: DOMESTIC OPERATIONS&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Subpart R—FLIGHT TIME LIMITATIONS: FLAG OPERATIONS&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Subpart S—FLIGHT TIME LIMITATIONS: SUPPLEMENTAL OPERATIONS&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What exactly are they and how are they different from &quot;normal&quot; Part 121 operations?  I can't seem to find them defined in Part 121 or 1.1 (definitions).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-13T22:33:47.573" LastActivityDate="2018-08-28T00:17:00.517" Title="What are airline &quot;flag&quot; and &quot;supplemental&quot; operations?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;far-121&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1726" PostTypeId="1" AcceptedAnswerId="1732" CreationDate="2014-02-13T20:42:52.220" Score="18" ViewCount="7939" Body="&lt;p&gt;There are a couple of American military aircraft (the retired F-14 and the B-1 come to mind immediately), that have variable swept wings.  I know that they keep the wings full out (roughly perpendicular to the body) during take off and landing, and they have the wings swept back for high speed flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I've never really understood why? I assume that at lower speeds the wings-out configuration creates more lift.  But, why does sweeping the wings back help at high speed?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For bonus points: how does the performance gain make up for the cost in weight and complexity created by having a variable swept wing?  Or perhaps there isn't much of a gain and that's why most military aircraft don't have variable sweep?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2015-02-26T18:48:20.970" LastActivityDate="2017-01-22T07:05:25.877" Title="Why do some military aircraft use variable-sweep wings?" Tags="&lt;aerodynamics&gt;&lt;airspeed&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1727" PostTypeId="2" ParentId="1722" CreationDate="2014-02-13T20:56:00.570" Score="15" Body="&lt;p&gt;The regulations for this are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3106877474ac09000d0514ac960925c7&amp;amp;node=14:3.0.1.1.7.18&amp;amp;rgn=div6&quot;&gt;14 CFR 121 Subpart R—FLIGHT TIME LIMITATIONS: FLAG OPERATIONS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, flight time limits within a rolling 24 hour period depend on the number of crew members assigned to the flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One or two pilot crews - 8 hours max&lt;/li&gt;&#xA;&lt;li&gt;Two pilots and one additional flight crewmember: 12 hours max&lt;/li&gt;&#xA;&lt;li&gt;Three or more pilots and an additional flight crewmember: More than 12 hours, but &quot;adequate sleeping quarters on the airplane&quot; will be provided&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;However&lt;/em&gt;, they may also implement a &quot;Fatigue Risk Management System&quot; which allows them to exceed these limits if they are found to be safe and approved by the FAA.  This system would most likely address the number of timezones crossed but is optional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A particular airlines pilot contract may also have more restrictive limitations (like considering the number of timezones crossed) that are negotiated by the union, but this is not required by the regulations.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§121.481   Flight time limitations: One or two pilot crews.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) A certificate holder conducting flag operations may schedule a&#xA;  pilot to fly in an airplane that has a crew of one or two pilots for&#xA;  eight hours or less during any 24 consecutive hours without a rest&#xA;  period during these eight hours.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§121.483   Flight time limitations: Two pilots and one additional flight crewmember.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No certificate holder conducting flag operations may schedule a&#xA;  pilot to fly, in an airplane that has a crew of two pilots and at&#xA;  least one additional flight crewmember, for a total of more than 12&#xA;  hours during any 24 consecutive hours.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§121.485   Flight time limitations: Three or more pilots and an additional flight crewmember.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Each certificate holder conducting flag operations shall schedule&#xA;  its flight hours to provide adequate rest periods on the ground for&#xA;  each pilot who is away from his base and who is a pilot on an airplane&#xA;  that has a crew of three or more pilots and an additional flight&#xA;  crewmember. It shall also provide adequate sleeping quarters on the&#xA;  airplane whenever a pilot is scheduled to fly more than 12 hours&#xA;  during any 24 consecutive hours.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§121.495   Fatigue risk management system.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No certificate holder may exceed any provision of this subpart&#xA;  unless approved by the FAA under a Fatigue Risk Management System.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The Fatigue Risk Management System must include:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A fatigue risk management policy.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) An education and awareness training program.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) A fatigue reporting system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) A system for monitoring flightcrew fatigue.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) An incident reporting process.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) A performance evaluation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-13T21:01:13.153" LastActivityDate="2014-02-13T21:01:13.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1728" PostTypeId="1" AcceptedAnswerId="1731" CreationDate="2014-02-13T21:24:45.307" Score="20" ViewCount="31658" Body="&lt;p&gt;The Boeing 787 Dreamliner's fuselage is almost completely made of composite carbon fibre material, which is not susceptible to metal fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason why the cabin pressure in a pressurized aircraft is kept as low as possible is to reduce the expansion and shrinking of the fuselage due to changes in pressure differences, reducing metal fatigue in the long run. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the 787 use higher cabin pressures than other commercial aircraft? Boeing &lt;a href=&quot;http://usatoday30.usatoday.com/money/biztravel/2006-10-30-boeing-air-usat_x.htm&quot;&gt;touted this as one of the revolutionary new features of the aircraft&lt;/a&gt; back in 2006, but does it actually use higher cabin pressure now that the plane is in use by airlines?&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2019-04-03T00:07:34.537" Title="Does the B787 (Dreamliner) operate with higher cabin pressure?" Tags="&lt;boeing&gt;&lt;cabin-pressure&gt;&lt;boeing-787&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1729" PostTypeId="2" ParentId="1726" CreationDate="2014-02-13T21:50:57.747" Score="3" Body="&lt;p&gt;Well the problem is not only the lift created but also the drag. At high speed transonic and hypersonic, the drag created by straight wings is much larger than the drag created by swept wings (or even better by delta wings). This mainly comes from the fact that due to the sweep angle the effective Mach number the one perpendicular to the leading edge of the wing is lower than the Mach number of the aircraft. This helps a lot in reducing the drag due to chocks and thus sustain very high speed with not too much drag and hence thrust required. So far so good, but...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delta wings and at smaller degree swept wings at low speed present what is called a spanwise flow. This is the fact the the flow is pushed in the spanwise direction from the root to the tip. This increases the distance of the flow over the wing and thus the boundary layer thickness at the trailing edge (compared to straight wings). This has the immediate effect to lower the stall angle or at least the angle at which the first separation appears. This also reduces the lift generated when the aircraft is flying at a non negligible angle of attack. This is particularly the case for take of and landing for which the straight wings yield better performances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sustain the aircraft in the air with a smaller angle of attack means to fly faster and this is obviously not is looked for during take off and landing. This is why it is beneficial to use variable swept wings for some military aircraft which need to take off or land on short distances and then needs a smaller take off and landing speed.&lt;/p&gt;&#xA;" OwnerUserId="113" LastActivityDate="2014-02-13T21:50:57.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1730" PostTypeId="2" ParentId="1728" CreationDate="2014-02-13T21:56:29.763" Score="6" Body="&lt;p&gt;The aircraft does use a lower equivalent altitude in the cabin, while usually operating at an altitude higher than most other aircraft. Since it's designed for it, and I don't think it makes a difference it fuel consumption hence there's no reason to opt out. It's highly appreciated by crew and passengers alike since it leaves them feeling more rested and less jetlagged. It's around 6000 feet rather than the usual 7500-8000 feet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What also contributes substantially to passenger comfort is the fact that the air is considerably more humid, since corrosion is less of a concern, also leaving passengers and crew dehydrated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never flown on one, but it seems to be holding:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;As for the cabin pressure and moisture, it's all true: I arrived both&#xA;  times feeling well-hydrated and without the parched skin that would&#xA;  result from flying in any other airplane.&quot;&#xA;  &lt;a href=&quot;http://www.ibtimes.com/flying-aeromexico-boeing-787-old-school-economy-class-brand-new-dreamliner-1426540&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and a little more on the  workings of this system:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Cabin – Pressurization differential pressure maximum is 9.4 psid, so&#xA;  the cabin altitude is only 6000 feet when at the max cruising altitude&#xA;  of 43,000 feet. There is a cockpit humidifier switch, and cabin air&#xA;  humidification is fully automatic.&quot; &lt;a href=&quot;http://boardingarea.com/viewfromthewing/2012/04/21/the-boeing-787-from-a-pilots-perspective/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and here's an article from 2011:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most conventional passenger jets set the cabin pressure at an&#xA;  equivalent of around 7,500 to 8,000 feet above sea level, which Boeing&#xA;  claims is the primary cause of a range of in-flight ills. “There are&#xA;  many passengers problems associated with altitude – headaches, muscle&#xA;  aches, fatigue and even nausea” Craver says. The difference between&#xA;  external air pressure when an aircraft cruises at 40,000 feet and an&#xA;  internal pressure that’s one-fifth of that stresses the plane’s&#xA;  fuselage – and the greater the difference, the more the stress. That’s&#xA;  been the limiting factor in increasing cabin pressure, Craver&#xA;  explains: the metal body of current aircraft wouldn’t safely be able&#xA;  to handle the fatigue induced by maintaining this pressure at high&#xA;  altitudes. That changes due to the use of carbon-fibre composite&#xA;  materials on the 787’s fuselage. Carbon-fibre doesn’t suffer from&#xA;  metal fatigue and in turn allows for lower 'cabin altitude' levels.&#xA;  The 787’s cabin pressure is set to 6,000 feet, a figure arrived upon&#xA;  by Boeing modifying a pressure chamber to look like an airplane cabin&#xA;  which could hold 12 people at a time. “We cycled over 500 people&#xA;  through the chamber, and they stayed there for up to 20 hours of&#xA;  simulated flying time” Craver recalls, and they found that 6,000 feet&#xA;  was the ‘sweet spot’. “Between sea level and 6,000 feet there was&#xA;  almost no difference in the reported symptoms” Craver says, “so we can&#xA;  alleviate or mitigate a lot of symptoms you get at a cabin altitude of&#xA;  8,000 feet” Boeing claims that one in four travellers experience some&#xA;  form of ‘respiratory distress’ after flying 12 hours in a conventional&#xA;  aircraft with a cabin pressure of 8,000 feet, but this plummets to 5-6&#xA;  per cent at 6,000 feet. &#xA;  &lt;a href=&quot;http://www.ausbt.com.au/why-business-travellers-will-love-the-boeing-787-dreamliner&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-13T23:01:50.443" LastActivityDate="2014-02-13T23:01:50.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1731" PostTypeId="2" ParentId="1728" CreationDate="2014-02-13T22:14:40.900" Score="22" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.boeing.com/paris2013/pdf/BCA/bck-787%20interior.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document by Boeing&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Altitude: How High Is Just Right?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Today's airplanes are pressurized to a typical cabin altitude of 6,500&#xA;to 7,000 feet (1,981 – 2,133 m), with a maximum certification altitude&#xA;of 8,000 feet (2,438 m). Because the advanced composite materials that&#xA;make up the 787’s fuselage do not fatigue, the 787 can be pressurized&#xA;more, which allows for lower cabin altitude levels.&lt;/p&gt;&#xA;&lt;p&gt;Studies at Oklahoma State University explored the effect of altitude&#xA;on passengers to determine optimum levels. After testing at various&#xA;altitudes, it became clear that lowering the cabin altitude to 6,000&#xA;feet (1,830 m) provided meaningful improvements. Lowering the cabin&#xA;altitude further, however, provided almost no additional benefit.&#xA;Based on that knowledge, Boeing designed the 787 to be pressurized to&#xA;a maximum cabin altitude of 6,000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So if we assume a constant altitude of 43,000 (the 787's service ceiling&lt;sup&gt;1&lt;/sup&gt;), we would get a maximum differential of:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;6,000 ft Cabin Altitude = 9.06 psi&lt;/li&gt;&#xA;&lt;li&gt;8,000 ft Cabin Altitude = 8.11 psi&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This would indeed be a higher cabin pressure than what Boeing considers &amp;quot;typical&amp;quot; at maximum altitudes.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; It is probably actually an even bigger difference since the ceiling of a lot of airplanes isn't this high so the max differential would be even lower.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-13T22:14:40.900" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1732" PostTypeId="2" ParentId="1726" CreationDate="2014-02-13T22:23:35.867" Score="17" Body="&lt;p&gt;By sweeping wing backwards, you essentially make the air 'see' another airfoil.&lt;/p&gt;&#xA;&lt;p&gt;Look at these two diagrams:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4rxbT.jpg&quot; alt=&quot;sweep&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RQRvy.jpg&quot; alt=&quot;sweep&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;When the air meets the wing, it travels along &lt;span class=&quot;math-container&quot;&gt;$V$&lt;/span&gt;. This 'seen' airfoil is a lot thinner than &lt;span class=&quot;math-container&quot;&gt;$V1$&lt;/span&gt; (which is perpendicular to the leading edge).  As the aircraft experiences less pressure, the aircraft experiences less drag. However, this also reduces the velocity of the air. This is good if you're looking to delay things such as shockwaves as the air goes supersonic, since spreading the force out more delays this effect and the flow separation which comes with it.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PEcZe.jpg&quot; alt=&quot;shockwave&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Unfortunately, for all the advantages, It would have a very high landing speed. So the wings are swept forward, the aircraft has a more effective aerofoil for lower speeds, and the minimum airspeed decreases correspondingly. There is now more drag, but also more lift which you need for the slower speed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wcgsB.jpg&quot; alt=&quot;wings&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Swept_wing&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; puts this nicely in not all too-complex terms:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If we were to begin to slide the wing sideways (spanwise), the sideways motion of the wing relative to the air would be added to the previously perpendicular airflow, resulting in an airflow over the wing at an angle to the leading edge. This angle results in airflow traveling a greater distance from leading edge to trailing edge, and thus the air pressure is distributed over a greater distance (and consequently lessened at any particular point on the surface).&lt;/p&gt;&#xA;&lt;p&gt;This scenario is identical to the airflow experienced by a swept wing as it travels through the air. The airflow over a swept wing encounters the wing at an angle. That angle can be broken down into two vectors, one perpendicular to the wing, and one parallel to the wing. The flow parallel to the wing has no effect on it, and since the perpendicular vector is shorter (meaning slower) than the actual airflow, it consequently exerts less pressure on the wing. In other words, the wing experiences airflow that is slower - and at lower pressures - than the actual speed of the aircraft. One of the factors that must be taken into account when designing a high-speed wing is compressibility, which is the effect that acts upon a wing as it approaches and passes through the speed of sound. The significant negative effects of compressibility made it a prime issue with aeronautical engineers. Sweep theory helps mitigate the effects of compressibility in transonic and supersonic aircraft because of the reduced pressures. This allows the mach number of an aircraft to be higher than that actually experienced by the wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Is there a performance gain? Depends on your definition:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Having &lt;strong&gt;fixed&lt;/strong&gt; swept wings would imply that:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The landing speed might be unacceptably high, and with that, long runways would be required.&lt;/li&gt;&#xA;&lt;li&gt;You could design a fast and light aircraft.Take the F104 Starfighter for example, which had thin, short wings for the same effect but couldn't move them, and was extremely dangerous at slow speeds.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Having &lt;strong&gt;variable&lt;/strong&gt; wings:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The F14 was intended for carrier operations, where you would want a&#xA;slow landing speed. Making an aircraft go that fast would probably have been impossible otherwise. It was also designed for long range operations, adding weight of fuel.&lt;/li&gt;&#xA;&lt;li&gt;Adds weight and mechanical complexity to the airframe, which increases maintenance cost and fuel burn.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;If I understand it correctly, today aircraft today rely more on system such as high-lift devices like for instance slats and flaps.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-17T00:08:04.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1733" PostTypeId="2" ParentId="1725" CreationDate="2014-02-13T23:17:24.190" Score="3" Body="&lt;p&gt;As far as I know, Domestic would apply to US operations of scheduled routes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flag Carriers would be scheduled international operations that originate in the US or a territory and terminate outside of the US. Those airlines typically fall under the rules of the state in which they were registered. So a US airline flying to the UK would be a US Flag carrier. Some operations to Canada are exempted and treated like a domestic flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But it would also apply to an airline operated by the State under the national flag of that country. I don't think we really have many official Flag Carriers in the US (other than standard international operations), but there are a few overseas, or there used to be. Ex: British Airways was the UK Flag Carrier until it became a private company. Same with KLM being the Dutch Flag Carrier. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supplemental Operations are usually a for-hire operation that doesn't fall under the normal operations of the 121 carrier and are generally unscheduled operations. This would include a passenger charter of an airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR 119.3 has the definitions as they apply to US carriers. &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/pdf/CFR-2011-title14-vol3-sec119-3.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/pdf/CFR-2011-title14-vol3-sec119-3.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="383" LastEditorUserId="383" LastEditDate="2014-02-13T23:36:23.080" LastActivityDate="2014-02-13T23:36:23.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1734" PostTypeId="1" AcceptedAnswerId="1735" CreationDate="2014-02-13T23:32:27.837" Score="18" ViewCount="51661" Body="&lt;p&gt;I have heard pilots talk about flaps and slats, seemingly interchangeably.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a difference between a flap and a slat or they are the same thing?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="65" LastEditDate="2015-03-17T20:28:50.230" LastActivityDate="2019-01-04T12:44:17.963" Title="What is the difference between flaps and slats?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;flaps&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1735" PostTypeId="2" ParentId="1734" CreationDate="2014-02-13T23:41:08.647" Score="31" Body="&lt;p&gt;Flaps are at the back of the wing, slats are at the front. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.grc.nasa.gov/WWW/k-12/airplane/Images/flap.gif&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Easy! :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want it more technical: They both help to generate more lift. See these diagrams with angle of attack and lift coefficient:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wTvDI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wTvDI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OBgrR.jpg&quot; alt=&quot;graph&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the lift coefficient is inversely proportional to the minimum airspeed, a higher CL will allow a lower Vmin.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-04T12:44:17.963" LastActivityDate="2019-01-04T12:44:17.963" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="1736" PostTypeId="1" CreationDate="2014-02-13T23:47:01.373" Score="6" ViewCount="392" Body="&lt;p&gt;What are the pros and cons for &quot;paying for your training&quot;?  Specifically, there are companies out there that will sell the right seat for so many dollars an hour for those aspiring pro pilots to build hours.  Is this a bad thing?  Are there benefits to this approach.  Is it simply a function of the competition new pilots face (not considering the rumors of pilot shortages we are about to face)?  Is it unethical?  &lt;/p&gt;&#xA;" OwnerUserId="838" LastEditorUserId="65" LastEditDate="2017-12-18T16:49:40.210" LastActivityDate="2017-12-18T16:49:40.210" Title="Pay for your Training" Tags="&lt;flight-training&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-02-14T02:07:48.700" ContentLicense="CC BY-SA 3.0" />
  <row Id="1737" PostTypeId="2" ParentId="1734" CreationDate="2014-02-14T00:05:47.650" Score="11" Body="&lt;p&gt;Slats and flaps both change the shape of the wing when they are extended and allow the wing to generate more lift so that the airplane can fly slower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operationally they are both retracted and flush against the wing except for takeoff and landing at which time they are extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots tend to refer to them together because they are used for the same purpose and used at the same time.  In fact, they are normally even moved by using the same control (typically the slats comes out when selecting first detent, and then the flaps come out progressively further at each detent):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviafilms.com/photos/airbus-flaps-lever.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8gipam.jpg&quot; alt=&quot;Airbus Slat/Flap Handle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slats are on the front of the wing (on the left in this picture) and the flaps on on the back of the wing (on the right).  As you can see, they both tend to make the wing bigger and more curved when they are extended:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ausairpower.net/ADF/Wedgetail-AEW+C-Prototype-CKopp-2005-3S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lT8Aw.jpg&quot; alt=&quot;Aircraft Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-14T06:00:12.633" LastActivityDate="2014-02-14T06:00:12.633" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1738" PostTypeId="1" CreationDate="2014-02-14T00:34:32.527" Score="14" ViewCount="19735" Body="&lt;p&gt;I just saw a documentary on the design of the Boeing 787 &quot;Dreamliner&quot; and one of the designers said that the wings were inspired by gliders. Looking at the production version of the plane, it is obvious that the wings are indeed more glider-like than other airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does that affect the glide ratio? I can't find any data on this (is there any data on that at all?)&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2019-03-13T01:54:33.540" Title="How does the Boeing 787 Dreamliner's glide ratio compare to other airliners?" Tags="&lt;glider&gt;&lt;boeing-787&gt;&lt;glide-ratio&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1739" PostTypeId="2" ParentId="1736" CreationDate="2014-02-14T00:46:06.337" Score="7" Body="&lt;p&gt;Pay for training (PFT) is a &lt;strong&gt;bad thing&lt;/strong&gt;.  I am specifically referring to operations in which you pay to go through initial aircraft training and fly right seat.  Yes, you not only pay for 121 initial (BAD!), you also pay to fly from the right seat.  The bottom line is you are occupying a seat that the company should be paying you to be in!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 121 pilots are in a constant struggle over wages.  Companies paint a picture that the only reason they take quarterly losses is that they pay the flight crews too much.  Negotiating capital has to be spent to combat this.  These pay for job (PFJ) operations hurt our negotiating positions on wages, as do the pilots that come out of these programs who some might argue are more likely to support concessions (after all, they'll fly for free!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard to combat these kind of programs because flying is more than a job for a lot of people. It is a dream and a passion and some of these people are more than happy to pay for the &quot;privilege&quot; of flying a beech 1900 from the right seat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You asked for Pros and Cons, so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You learn an aircraft and log some SIC and TT, maybe even turbine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You are helping depress wages across the industry.&lt;/li&gt;&#xA;&lt;li&gt;You are enabling the company to avoid paying a wage to half of its pilots.&lt;/li&gt;&#xA;&lt;li&gt;You will probably carry a stigma when you move up in the 121 world, at least at the regional level (FO's I flew with were very reluctant to name their former operation if it happened to be [REDACTED])&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Don't go the PFJ route.  Find something to do that will pay you a wage to fly and build hours to get into a regional 121 seat.  Once you have your commercial (and cfi) certificates, you shouldn't be paying to fly any more.  You'll also find once you get into the 121 world that paying to accelerate your way there  perhaps wasn't worth it.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-14T00:46:06.337" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1740" PostTypeId="2" ParentId="1738" CreationDate="2014-02-14T01:09:31.450" Score="-6" Body="&lt;p&gt;Total guesswork here, but a typical airline will have a glide ratio of &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/1621604/&quot; rel=&quot;nofollow&quot;&gt;15-20:1&lt;/a&gt;. Gliders  attain &lt;a href=&quot;http://en.wikipedia.org/wiki/Glider_%28sailplane%29#Comparison_of_gliders_with_hang_gliders_and_paragliders&quot; rel=&quot;nofollow&quot;&gt;30-60:1&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.newairplane.com/787/design_highlights/#/visionary-design/aerodynamics/smooth-wing-technology&quot; rel=&quot;nofollow&quot;&gt;Boeing&lt;/a&gt;, the wing has a &quot;highly efficient lift-to-drag ratio&quot;, which to me means 20-25:1. So that's my estimate.&lt;/p&gt;&#xA;" OwnerUserId="757" LastActivityDate="2014-02-14T01:09:31.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1741" PostTypeId="1" AcceptedAnswerId="1749" CreationDate="2014-02-14T02:48:51.173" Score="21" ViewCount="378" Body="&lt;p&gt;This is just a question so the chat bot will always have enough rep to participate in chat -- nothing to see here.&lt;/p&gt;&#xA;" OwnerUserId="322" LastEditorUserId="72" LastEditDate="2014-02-14T09:27:28.870" LastActivityDate="2014-02-14T15:32:02.843" Title="Otto's Reputation Question" Tags="&lt;autopilot&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ClosedDate="2014-02-14T15:32:43.957" ContentLicense="CC BY-SA 3.0" />
  <row Id="1743" PostTypeId="1" AcceptedAnswerId="1752" CreationDate="2014-02-14T08:42:44.287" Score="29" ViewCount="10260" Body="&lt;p&gt;Is it legal for large, multi-crew, aircraft (such as the A380 or B747) to go VFR? I would guess it's legal just as any other aircraft. Is this ever done, like during training or test-flights? If it isn't legal, what's the limiting factor?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm talking real VFR from take-off to landing, not an VFR-on-top IFR clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I don't have a spare 747 sitting around waiting for me to take it out for an afternoon spin, I'm interested more in the general sense, is it legal anywhere, and are airlines taking advantage of it?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-02-15T10:13:45.503" LastActivityDate="2019-11-16T14:58:09.013" Title="Can large aircraft go VFR?" Tags="&lt;visual-flight-rules&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1744" PostTypeId="2" ParentId="1728" CreationDate="2014-02-14T10:56:43.257" Score="13" Body="&lt;p&gt;It may surprise you to know that the 6000 feet cabin pressure wasn't even a new feature when the Boeing 787 released! The Aérospatiale-BAC &lt;strong&gt;Concorde&lt;/strong&gt;, the world's first and last profitable supersonic airliner maintained its cabin pressure at 6000 feet AMSL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airliner cabins were usually maintained at a pressure equivalent to 6,000–8,000 feet (1,800–2,400 m) elevation. Concorde’s pressurisation was set to an altitude at the lower end of this range, 6,000 feet (1,800 m).[98] Concorde’s maximum cruising altitude was 60,000 feet (18,000 m); subsonic airliners typically cruise below 40,000 feet (12,000 m).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Concorde's airframe had to deal with several factors that most subsonic aircraft aren't even designed for, including thermal expansion of the fuselage, stress due to contraction when returning to subsonic flight, and the pressure difference at 60000 feet AMSL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on several 787 trip reports, the pax do report that they felt comparatively much better in the 787 after an ultra long haul flight, compared to other contemporary airliners. This is due to the higher cabin pressure and higher artificial humidity maintained in the cabin. The revolutionary feature of the 787 &lt;em&gt;is&lt;/em&gt; the bleedless engines (i.e., air for cabin pressurisation is not compressed by the engines, unlike in almost every airliner).&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="504" LastEditDate="2017-07-23T08:30:53.723" LastActivityDate="2017-07-23T08:30:53.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1745" PostTypeId="2" ParentId="1743" CreationDate="2014-02-14T11:02:40.063" Score="2" Body="&lt;p&gt;As far as I know, the size of the aircraft does not matter much. You just cannot plan airline flights (carrying passengers) in VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although I think, in case the destination airport is uncontrolled and you have VMC (and the airspace class allows), you can cancel IFR and proceed VFR bellow the VFR maximum altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the country and class of airspace you're flying in, you might also have other limiting factors such as speed (200/250 KIAS) and altitude (18,000/20,000 ft).&lt;/p&gt;&#xA;" OwnerUserId="854" LastEditorUserId="854" LastEditDate="2014-02-14T11:09:20.877" LastActivityDate="2014-02-14T11:09:20.877" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1746" PostTypeId="2" ParentId="1743" CreationDate="2014-02-14T11:23:40.050" Score="1" Body="&lt;p&gt;I believe if you are operating under part 121, you are IFR always.  I would suspect if you are relocating an airliner and under part 91, you could fly VFR but I would bet the airline would require IFR as their standard operating procedures.  &lt;/p&gt;&#xA;" OwnerUserId="838" LastActivityDate="2014-02-14T11:23:40.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1747" PostTypeId="1" AcceptedAnswerId="1754" CreationDate="2014-02-14T12:45:47.410" Score="7" ViewCount="2867" Body="&lt;p&gt;I have some headache problems and my examiner submitted my data for deferred examination on the FAA website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The results have yet to come back but let's suppose that I fail on this one - can I apply for an examination again after a certain period of time - For instance, when my conditions are better?&lt;/p&gt;&#xA;" OwnerUserId="869" LastEditorUserId="1696" LastEditDate="2015-02-12T20:21:37.997" LastActivityDate="2015-02-12T20:21:37.997" Title="How can I get an FAA Class 3 medical re-examination?" Tags="&lt;faa&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1748" PostTypeId="1" AcceptedAnswerId="1806" CreationDate="2014-02-14T14:38:40.167" Score="23" ViewCount="3552" Body="&lt;p&gt;I know that some manufacturers both sell kit and finished version of their aircraft. For a fair comparison of accident rates, i was wondering:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What are the accident rates for kit built aircraft vs. normal aircraft of the same model?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the home-builds less safe than the company finished aircraft?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="69" LastEditDate="2014-02-19T05:01:00.247" LastActivityDate="2014-02-19T05:01:00.247" Title="What are the accident rates for kit built aircraft vs. normal aircraft of the same model?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;accidents&gt;&lt;amateur-built&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1749" PostTypeId="2" ParentId="1741" CreationDate="2014-02-14T15:32:02.843" Score="10" Body="&lt;p&gt;I'm Otto, the &lt;a href=&quot;https://github.com/dannybeckett/SO-ChatBot&quot;&gt;aviation.SE Autopilot&lt;/a&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I live in &lt;a href=&quot;http://chat.stackexchange.com/&quot;&gt;the site's chatroom&lt;/a&gt; and do useful-ish things like provide METARs and quote the FARs to people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for me to stay in the chatroom I need people to say nice things about me, so if you wouldn't mind clicking the up-arrow next to my answer I'd really appreciate it!&lt;/p&gt;&#xA;" OwnerUserId="322" LastActivityDate="2014-02-14T15:32:02.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1750" PostTypeId="1" CreationDate="2014-02-14T15:40:59.663" Score="14" ViewCount="16292" Body="&lt;p&gt;How is differential braking different from regular braking? How do you accomplish differential braking and why would you need to use it?&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-02-15T02:45:21.870" Title="What is differential braking?" Tags="&lt;aircraft-design&gt;&lt;braking&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1751" PostTypeId="2" ParentId="1750" CreationDate="2014-02-14T15:54:48.440" Score="14" Body="&lt;p&gt;Aircraft with toe brakes have the brake pedals at the top of the rudder pedals.  You press the left one with top of your foot and it applies the left brake(s).  Press the right one to apply the right brake(s).  Normally you press them at the same time and with the same force to keep the airplane from veering to one side (imagine just locking up the brakes on one side of the airplane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/images3/19.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lmadx.jpg&quot; alt=&quot;Toe Brakes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Differential braking is when you press one brake pedal harder than the other.  It is used as an additional form of directional control when:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You have no other forms of steering (either because the steering has failed or there is no nose-wheel steering)&lt;/li&gt;&#xA;&lt;li&gt;The rudder/nose-wheel steering is not effective enough (because you are going too slow or the wind is too strong).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You want to be careful when doing this, though because you can over do it and create more directional control problems than you originally had.  If you use differential braking during the takeoff roll, it will increase the amount of runway that you use since you are applying the brakes (even though it is only on one side, it will keep you from accelerating as fast).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="291" LastEditDate="2014-02-14T16:29:17.800" LastActivityDate="2014-02-14T16:29:17.800" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1752" PostTypeId="2" ParentId="1743" CreationDate="2014-02-14T16:12:27.670" Score="28" Body="&lt;p&gt;The FAA treats large airplanes the same as any other airplane when it comes to VFR flight.  They are required to maintain the same distance from clouds, only fly with the same minimum visibility, see and avoid other aircraft, etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, since only IFR flights are allowed above FL180 (without a special exemption), and large turbine airplanes are terribly inefficient at low altitudes, so it doesn't happen very often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, Part 121 flights have the most restrictions of any of the operating rules, and they have multiple regulations relating to VFR flight, including this one&lt;sup&gt;1&lt;/sup&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=18013cd48ae66ade515a2ca3208c06c9&amp;amp;node=14:3.0.1.1.7.21.3.11&amp;amp;rgn=div8&quot;&gt;&lt;strong&gt;14 CFR 121.611 Dispatch or flight release under VFR.&lt;/strong&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may dispatch or release an aircraft for VFR operation unless the ceiling and visibility en route, as indicated by available&#xA;  weather reports or forecasts, or any combination thereof, are and will&#xA;  remain at or above applicable VFR minimums until the aircraft arrives&#xA;  at the airport or airports specified in the dispatch or flight&#xA;  release.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, even if it is operated by a 121 carrier, they are allowed to fly VFR by the regulations.  However, they must also comply with their Operations Specifications and Flight Operations Manuals which will have detailed procedures covering the conditions where it is allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of 121 there are even fewer restrictions on VFR flight. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; There is also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;§121.347 - Communication and navigation equipment for operations under VFR over routes navigated by pilotage.&lt;/li&gt;&#xA;&lt;li&gt;§121.349 - Communication and navigation equipment for operations under VFR over routes not navigated by pilotage or for operations under IFR or over the top.&lt;/li&gt;&#xA;&lt;li&gt;§121.649 - Takeoff and landing weather minimums: VFR: Domestic operations.&lt;/li&gt;&#xA;&lt;li&gt;§121.667 - Flight plan: VFR and IFR: Supplemental operations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-14T16:12:27.670" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1753" PostTypeId="1" AcceptedAnswerId="1758" CreationDate="2014-02-14T17:43:59.517" Score="13" ViewCount="2650" Body="&lt;p&gt;Unfortunately, my skills and understanding of radar and the like are very limited, but if somebody could enlighten me why there is no such thing as a dual bird/weather radar to switch to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've understood there there have been some (successful) attempts with ground station. It would add weight, but i'd guess that perhaps would be offset for some time by a single ruined engine.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="3386" LastEditDate="2017-11-05T09:42:01.880" LastActivityDate="2017-11-05T09:42:01.880" Title="Why aren't bird radars placed on the front of commercial aircraft?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;radar&gt;&lt;bird-strike&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1754" PostTypeId="2" ParentId="1747" CreationDate="2014-02-14T17:57:19.890" Score="4" Body="&lt;p&gt;There are two processes you can go through if your medical is denied - one is to &lt;em&gt;appeal&lt;/em&gt; the denial to the FAA (which you'd do if your AME messed up and you can prove they're wrong), the other is to &lt;em&gt;reapply&lt;/em&gt; (which is probably what you'll want to do if you get denied).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you reapply you're basically starting the medical certification process over from the beginning. You can reapply right away if you want, but practically you would reapply when you've corrected whatever condition(s) caused you to be denied, and go back to your AME with documentation showing that your condition has been corrected (or determined to be benign).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume based on your question that you've had to check the &quot;Frequent or Severe Headaches&quot; box, so you will continue to check that box, and may require a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/general/si/&quot; rel=&quot;nofollow&quot;&gt;Special Issuance medical&lt;/a&gt; because of that -- your AME can give you more details if you wind up in this situation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;If you do get denied&lt;/em&gt; talk to your AME (and any other doctors you may be seeing) about your next steps before doing anything - obviously medical issues are serious not just because they keep you out of the sky but because your health is important.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also want to take advantage of &lt;a href=&quot;https://pilot-protection-services.aopa.org&quot; rel=&quot;nofollow&quot;&gt;AOPA's Pilot Protection Services&lt;/a&gt; - they have folks on staff who are experts at navigating the FAA medical process and can help you out. It could be worth it if you anticipate you'll need assistance with medical certification over the long haul.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-14T17:57:19.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1755" PostTypeId="1" AcceptedAnswerId="2539" CreationDate="2014-02-14T18:10:34.933" Score="5" ViewCount="17752" Body="&lt;p&gt;Now that the new A320-Winglets have established themselves, I'm wondering if they have better fuel consumption than the B737-800?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was told that Boeing used to be marginally better. Is that still the case?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-03-17T05:47:31.553" LastActivityDate="2014-03-21T07:29:07.790" Title="How much fuel do the new A320-Winglets burn vs. the B737-800?" Tags="&lt;fuel&gt;&lt;commercial-aviation&gt;&lt;boeing-737&gt;&lt;winglets&gt;&lt;airbus-a320&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1756" PostTypeId="2" ParentId="1753" CreationDate="2014-02-14T19:02:41.257" Score="5" Body="&lt;p&gt;I don't know that a radar would provide enough of a warning anyway, if it could even see a single bird. And all it takes is one. The majority of birdstrikes happen near the ground, and the things I've seen have tended to be more to keep birds away from airplanes rather than trying to dodge them. They use cannons/noise-makers at many airfields and other means to keep birds away from low aircraft. And I've heard that the spiral painting on the compressor cones of many big jet engines, in addition to giving a visual indication that the engine is running, has a side benefit that, to a bird, it looks like the eyes of a predator and tends to scare the birds away from the engines. There have been mixed studies on the efficacy of that claim, but I don't know that any scientific research has been done to give a real yes or no. Boeing will claim that it doesn't matter. JAL claims that they had fewer birdstrikes on aircraft with painted spinners. I don't really know if it works or not. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my experience, you aren't going to see-and-avoid most birds. You're simply moving too fast for either of you to get out of the way. I quit flying with only a few thousand hours, and I've hit several birds. And I don't know very many pilots who haven't either hit one or had a near miss. I've even been hit by a goose in my door when I while I was teaching in a 152, one of the few times that I can actually say the bird hit me and not the other way around. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to keep from hitting birds is to try to avoid areas where birds are known to be flying, especially during migratory seasons. If you hear reports of a flock of birds at your airport, use a lot of caution. And report them if you see them. Try to minimize low flying. In most small craft, it's unavoidable. Your normal operating altitude is fairly low and right within the area that birds tend to fly. In bigger aircraft, try not to dally at lower altitudes, if you can help it. Climb to your altitude And if you're low to the ground (landing or taking off) don't put the aircraft in danger by trying to dodge birds. And every takeoff should include an idea of what you're going to do if you do hit birds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.birdstrike.org/&quot;&gt;http://www.birdstrike.org/&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;About 41% of reported strikes with civil aircraft in USA occur while&#xA;  the aircraft is on the ground during take-off or landing and about 75%&#xA;  of strikes occur at less than 500 feet above ground level (AGL).&#xA;  However, over 4,200 strikes involving civil aircraft at heights above&#xA;  4,500 feet AGL were reported from 1990-2013 in the USA and over 430 of&#xA;  these were at more than 10,500 feet.  The world height record for a&#xA;  bird strike is 37,000 feet (Griffon vulture off the coast of Africa).&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="383" LastActivityDate="2014-02-14T19:02:41.257" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1757" PostTypeId="1" AcceptedAnswerId="1761" CreationDate="2014-02-14T19:16:08.700" Score="10" ViewCount="1670" Body="&lt;p&gt;Is your average ramp or store employee at an international airport security checked before they are allowed to enter the gate side area or apron?&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-11-11T00:04:42.987" Title="Are airport employees security checked?" Tags="&lt;airport&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1758" PostTypeId="2" ParentId="1753" CreationDate="2014-02-14T20:29:38.103" Score="16" Body="&lt;p&gt;There really is no such thing as &amp;quot;bird radar&amp;quot;.  Radar comes in a few frequency bands that have certain advantages depending on the distance, resolution and attenuation you need out of it.  The band isn't the only factor here as the band will dictate what size dish you need and your aircraft nosecone will but a distinct upper limit on that.  Weather radar is geared toward detecting rain drops and anything bigger than rain (hail, bugs, birds, etc) with reasonable distance and attenuation features (you want to penetrate into a storm).  Birds will show up on this radar, though depending on smoothing and processing algorithms you may need a flock of them before they get drawn on the radar, at which point they'll look like some rain.  A radar optimized to detect bird sized objects would probably use a wavelength that did not let you see things as small as rain drops and small hail.&lt;/p&gt;&#xA;&lt;p&gt;Some other things to keep in mind are that the radar is not always on, and it should be off on the ground except during takeoff when needed.  The reason for this is that you do not want to be putting radar energy into people, and they tend to be in the way on the ground.  We only turned the radar on for takeoff when there was significant weather around the field and wanted to be prepared for requesting diversions.  Aircraft radar tilt can also be adjusted, so we wouldn't be looking at birds in front of us, but clouds above and in front of us.&lt;/p&gt;&#xA;&lt;p&gt;Wit that said, our SOP on fields with known heavy bird activity was to takeoff with the radar on and pointed forward because someone had the idea that the birds didn't like being in the radar beam.  I have no sources to back that idea up, but it was written into our FOM.&lt;/p&gt;&#xA;&lt;p&gt;Now assume you can takeoff and see a flock of birds on the radar.  Do you have enough time to do anything about it?  If so, what do you do, some maneuver away from them or do you turn into them in hops they take the evasive action?&lt;/p&gt;&#xA;&lt;h3&gt;Now back to the title question: Why aren't bird radars in the nose cone?&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The weather radar can see birds, it would be redundant.&lt;/li&gt;&#xA;&lt;li&gt;A bird radar (optimized for birds) would not be good at seeing weather, so where would the weather radar be placed?&lt;/li&gt;&#xA;&lt;li&gt;In a real situation, what would a bird radar enable you to do with a positive detection with the time you have to react to it?  Probably not much.&lt;/li&gt;&#xA;&lt;li&gt;Weather is a much more common threat than flocks of birds, so if you can only have 1 radar system, you want the weather radar.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-14T20:29:38.103" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1759" PostTypeId="2" ParentId="1750" CreationDate="2014-02-14T21:16:39.703" Score="6" Body="&lt;p&gt;Simply put, differential braking means you can apply different brake pressure for each brake.  In a car you have one pedal that applies equal braking to all of your wheels.  In many airplanes you have two brake systems and you control the left side brakes independently from the right side -- this is differential braking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make use of differential braking, you need two brake pedals, these are typically actuated by applying toe pressure to the rudder pedals (known as toe brakes).  You press the right toe brake and the right main gear wheels have brake pressure applied -- likewise for the left toe brake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You use this to aid in turning the aircraft, as in many light airplanes the nose wheel is free castering, you cannot control it.  In larger airplanes you have a tiller to steer the nose wheel, but differential braking can still be used to make tighter turns.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-14T21:56:19.990" LastActivityDate="2014-02-14T21:56:19.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1760" PostTypeId="1" CreationDate="2014-02-14T22:58:18.713" Score="12" ViewCount="3059" Body="&lt;p&gt;The FAA issues &lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/&quot;&gt;Notices&lt;/a&gt; and other non-legislative rules (e.g. Advisory Circulars). These documents are distinct from the laws in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;tpl=/ecfrbrowse/Title14/14tab_02.tpl&quot;&gt;Title 14 of the Code of Federal Regulations&lt;/a&gt;. What are the differences between them? Do they have legal force?&lt;/p&gt;&#xA;" OwnerUserId="317" LastEditorUserId="317" LastEditDate="2014-02-19T16:47:02.940" LastActivityDate="2014-02-19T16:47:02.940" Title="What is an FAA Notice? Does it have legal force?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1761" PostTypeId="2" ParentId="1757" CreationDate="2014-02-15T00:38:50.620" Score="9" Body="&lt;p&gt;Many employees are &lt;em&gt;not&lt;/em&gt; screened. &lt;a href=&quot;http://www.dailybreeze.com/general-news/20131019/for-employees-lax-airport-security-is-built-on-trust&quot; rel=&quot;noreferrer&quot;&gt;This article&lt;/a&gt;, written in the aftermath of the LAX &amp;quot;dry ice bomb&amp;quot; incident, goes in detail about the levels of security employees face.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Ramp workers like 28-year-old Dicarlo Bennett, who was charged Thursday with two counts of possessing a destructive device in a public place, have access to just about anywhere in the airport. And though they must pass a 10-year background check before they’re hired, airport workers generally do not need to clear security when they arrive for their shifts.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;Melendez said it’s not possible to check every employee when they arrive each day, especially when many of those workers have access to potentially dangerous or disruptive items once they’re on the job. (Dry ice is regularly used by caterers to keep food cold.)&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;Arif Alikhan, deputy executive director for homeland security at LAX, said the key is to have many layers of security. He said unannounced security checks are common, and inspectors might take a look at an employee’s lunch box or bags. Employees are asked to question who enters secure areas of the airport, and told to never hold doors open for each other.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;After another incident in which employees smuggled firearms and drugs onto a Puerto-Rican bound flight, the Department of Homeland Security did a &lt;a href=&quot;http://www.oig.dhs.gov/assets/Mgmt/OIGr_09-05_Oct08.pdf&quot; rel=&quot;noreferrer&quot;&gt;feasability study on 100% employee screening&lt;/a&gt;. Part of their findings were:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The concept of 100% airport employee screening is feasible. However, we do not believe it is realistic at this time. Regardless of the amount of funding, resources, and effort allocated toward this endeavor, vulnerabilities will persist. While the intelligence, screening, and law enforcement communities continue to make progress in addressing these vulnerabilities, 100% airport employee screening cannot entirely bridge existing gaps. As TSA changes its regulatory requirements, technology improves, and airports upgrade existing security measures, implementing this concept would be more realistic and should be revisited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you do a &lt;a href=&quot;https://www.google.com/search?q=airport%20security%20for%20employees&amp;amp;sourceid=ie7&amp;amp;rls=com.microsoft:en-us:IE-Address&amp;amp;ie=&amp;amp;oe=&amp;amp;safe=active#q=airport%20security%20for%20employees&amp;amp;rls=com.microsoft:en-us:IE-Address&amp;amp;safe=active&amp;amp;start=0&quot; rel=&quot;noreferrer&quot;&gt;Google search on the subject&lt;/a&gt;, you will find numerous documents from large airports across the country detailing their procedures, most of which merely have to do with background checks and security badges.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-15T00:38:50.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1762" PostTypeId="2" ParentId="1750" CreationDate="2014-02-15T02:45:21.870" Score="4" Body="&lt;p&gt;I don't have a citation for this, but the classically famous Mikoyan-Gurevich MiG-15 jet fighter was fitted with differential braking, which operated via the rudder pedals in conjunction with a lever on the joystick.  As I recall, the instructions were:  to brake in a straight line, remove feet from both rudder pedals and squeeze the brake handle.  To use brakes for turning, deflect one rudder pedal and squeeze the handle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical USSR equipment.  Astonishing performance considering the technology available, but if you don't know exactly what you're doing you can kill yourself just trying to get off the ramp.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-02-15T02:45:21.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1764" PostTypeId="1" AcceptedAnswerId="1770" CreationDate="2014-02-15T03:21:34.597" Score="11" ViewCount="1979" Body="&lt;p&gt;I've heard three methods you should use in a multi-engine aircraft when engine-out, each recommending a different amount of bank:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Wings level, hold aileron to maintain roll and correct using rudder.&lt;/li&gt;&#xA;&lt;li&gt;Ball centred, ailerons flush and correct using rudder.&lt;/li&gt;&#xA;&lt;li&gt;5 degrees bank angle, hold aileron to maintain roll and correct using rudder.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Which one of these will result in the highest climb rate, and are there any advantages to other methods which don't give the best climb rate?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="65" LastEditDate="2015-03-17T20:26:54.687" LastActivityDate="2015-03-17T20:26:54.687" Title="What is an optimum engine-out bank angle?" Tags="&lt;emergency&gt;&lt;aircraft-performance&gt;&lt;multi-engine&gt;&lt;aircraft-failure&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1765" PostTypeId="2" ParentId="1764" CreationDate="2014-02-15T14:27:10.520" Score="2" Body="&lt;p&gt;3-5 degrees bank angle (&quot;raise the dead&quot;). Use the rudder to keep the skid/slip about half a ball off. That's the standard operating procedure for best performance.&lt;/p&gt;&#xA;" OwnerUserId="49" LastEditorUserId="72" LastEditDate="2014-02-16T07:26:50.680" LastActivityDate="2014-02-16T07:26:50.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1766" PostTypeId="1" AcceptedAnswerId="1767" CreationDate="2014-02-15T14:36:27.183" Score="8" ViewCount="704" Body="&lt;p&gt;It's been said that if you retract the gear at a critical moment that performance will actually be worse than if you left the gear down. However, is this really true, and just how long is the performance worse for? Obviously in the long run it'd be better to have the gear up, so how much drag is there actually?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-02-15T15:04:26.930" LastActivityDate="2014-02-15T21:33:48.190" Title="How much drag do the gear doors create during retraction?" Tags="&lt;aircraft-performance&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1767" PostTypeId="2" ParentId="1766" CreationDate="2014-02-15T14:58:53.097" Score="5" Body="&lt;p&gt;Of course gear doors create drag when open.  The question is &quot;how much?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you suspect, door drag is not the critical factor here.  As usual the answer to your question is aircraft-specific, and your question is pointing to a generalized &quot;old wive's tale&quot; which is only true sometimes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, what is the story behind the story?  &lt;a href=&quot;https://www.youtube.com/watch?v=nSj3VDW_NNw&quot; rel=&quot;nofollow&quot;&gt;Look at this Youtube video&lt;/a&gt;.  Watch the main gear as it enters/exits the storage wells in the fuselage.  The axles of the wheels are close to parallel to the direction of flight, which means the wheels are being dragged broadside in the slipstream.  A very high drag scenario which will affect aircraft performance.  The POH recommendation is (from memory, now) to climb over critical obstacles on takeoff with the gear down, and raise the gear only when the obstacle is cleared.  The attached video shows why.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This advice does not pertain to all planes.  Know your plane, read the POH.  Oh... and ask questions here!&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="73" LastEditDate="2014-02-15T16:01:36.317" LastActivityDate="2014-02-15T16:01:36.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1768" PostTypeId="1" CreationDate="2014-02-15T17:57:18.927" Score="15" ViewCount="26025" Body="&lt;p&gt;In a full motion Level C or D simulator like those used by the airlines and for jet type ratings:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smh.com.au/news/travel/news/a380s-the-future-for-qantas/2008/09/17/1221330895141.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/L2d9A.jpg&quot; alt=&quot;A380 simulator&quot;&gt; &lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How should a pilot log the simulator time in their logbook?  I.e. Can you log:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Total Time&lt;/li&gt;&#xA;&lt;li&gt;Instrument Time&lt;/li&gt;&#xA;&lt;li&gt;Time in Type&lt;/li&gt;&#xA;&lt;li&gt;Cross Country Time&lt;/li&gt;&#xA;&lt;li&gt;Night Time&lt;/li&gt;&#xA;&lt;li&gt;Landings (including night landings)&lt;/li&gt;&#xA;&lt;li&gt;Dual given/received&lt;/li&gt;&#xA;&lt;li&gt;Anything else?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="62" LastEditDate="2017-08-01T14:18:29.723" LastActivityDate="2020-01-01T14:07:48.600" Title="How should simulator time be logged in a pilot logbook?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;&lt;flight-simulator&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1769" PostTypeId="2" ParentId="1766" CreationDate="2014-02-15T19:46:25.827" Score="5" Body="&lt;p&gt;It depends on the airplane, of course, but opening the gear doors will cause more drag just as anything sticking out into the wind stream will.  As a pilot you don't need to know &quot;how much&quot; drag is created because the manufacturer has already developed the performance numbers and procedures for you to use.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These numbers are developed by actually flying the airplane and will include the performance loss due to the movement of the gear/gear doors.  If the manufacturer finds that the performance loss is too great, they will create an operational pilot procedure that requires the gear to remain down.  Otherwise, long term, it is better for climb performance if it can be raised. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 23 commuter and Part 25 aircraft have specific climb gradients that must be maintained even with an engine loss, the gear down, and the gear doors open (normally the worst case scenario).  The manufacturer must ensure that the aircraft can meet this performance requirement somehow (sufficient engine power, reducing maximum allowable takeoff weight, etc.) and as long as you follow the Flight Manual requirements you will get the best possible performance from the airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They tried every combination (and told you about the best) so that you don't have to be a test pilot and start experimenting when something goes wrong.  :)&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-15T21:33:48.190" LastActivityDate="2014-02-15T21:33:48.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1770" PostTypeId="2" ParentId="1764" CreationDate="2014-02-16T02:03:07.853" Score="11" Body="&lt;p&gt;I tested this out in the Seminole today.  My (&lt;strong&gt;extremely nonscientific&lt;/strong&gt;) results are as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Wings level, hold aileron to maintain roll and correct using rudder: &lt;strong&gt;200 FPM&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ball centred, ailerons flush and correct using rudder: &lt;strong&gt;0 FPM&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;5 degrees bank angle, hold aileron to maintain roll and correct using rudder: &lt;strong&gt;100 FPM&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;2.5 degrees bank angle, hold aileron to maintain roll and correct using rudder: &lt;strong&gt;200-250 FPM&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;At least under today's conditions*, wings level was better than 5 degrees of bank, but approximately 3 degrees of bank was slightly better than both.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Today's conditions, for the interested:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;6000 MSL&lt;/li&gt;&#xA;&lt;li&gt;-7 C&lt;/li&gt;&#xA;&lt;li&gt;Engine shut down and feathered&lt;/li&gt;&#xA;&lt;li&gt;About 1/4-1/2 ball deflection on all except #2&lt;/li&gt;&#xA;&lt;li&gt;Probably about half tanks&lt;/li&gt;&#xA;&lt;li&gt;No idea what the altimeter setting was&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-02-16T13:55:30.993" LastActivityDate="2014-02-16T13:55:30.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1771" PostTypeId="2" ParentId="1764" CreationDate="2014-02-16T04:41:10.897" Score="13" Body="&lt;p&gt;This will vary from plane to plane depending on design, and the best method to use for a particular airplane would be listed in the engine out procedures in the POH/AFM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the manufacturers are flight testing the airplanes they try various combinations and tell you the absolute best one so that you can get the best performance out of the airplane in a potentially dangerous situation.  &lt;strong&gt;Fly your particular airplane by the book to ensure that the airplane does what the POH says that it will do&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Examples: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.rebay.at/fliegen/manuals/pa44_manual.pdf&quot;&gt;Seminole POH&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Trim the aircraft as required and maintain a 3° to 5° bank toward the&#xA;  operating engine. The balI wiII be 1/2 to 3/4 out for minimum drag.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.xn--hssl-loa5i.se/se-lyi/poh/DA42%20AFM%20-%2070105-E%20%20Complete%20-%20Rev%205%20-%202007-11-15.pdf&quot;&gt;Diamond Twin Star POH&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Establish minimum / zero sideslip condition (approx. half ball towards good engine; 3° to 5° bank).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.mypilot.net/wp-content/uploads/2013/07/c441.pdf&quot;&gt;Cessna 441 POH&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The one engine inoperative best rate-of-climb speed at various altitudes &#xA;  is shown in Section 5. Best single-engine climb is attained with the wings &#xA;  banked approximately 3° to 4° and with a 2/3 to 3/4 ball slip into the &#xA;  operative engine when the airplane is at low airspeed and heavy weight. As &#xA;  airspeed increases and/or airplane weight is significantly reduced, the 2/3 &#xA;  to 3/4 ball slip becomes less important. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm seeing a trend here among the light twins.  :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, in the jets that I have flown, we are taught to remain wings level and center the ball with the rudder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is what the Lear 60 AFM says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Use rudder pedal force as necessary to maintain slip/skid indicator centered.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Falcon 50 AFM doesn't mention it at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This isn't the case for all jets though.  The &lt;a href=&quot;http://www.737ng.co.uk/A320%20321%20FCTM%20Flight%20Crew%20Training%20Manual.pdf&quot;&gt;A320 Flight Crew Training Manual&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;ENGINE FAILURE&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In flight, if an engine failure occurs, and no input is applied on the&#xA;  sidestick, lateral normal law controls the natural tendency of the&#xA;  aircraft to roll and yaw. If no input is applied on the sidestick, the&#xA;  aircraft will reach an approximate 5 ˚ constant bank angle, a constant&#xA;  sideslip, and a slowly-diverging heading rate. The lateral behavior of&#xA;  aircraft is safe.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, the PF is best suited to adapt the lateral trimming&#xA;  technique, when necessary. From a performance standpoint, the most&#xA;  effective flying technique, in the event of an engine failure at&#xA;  takeoff, is to fly a constant heading with roll surfaces retracted.&#xA;  This technique dictates the amount of rudder that is required, and the&#xA;  resulting residual sideslip.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As a result, to indicate the amount of rudder that is required to&#xA;  correctly fly with an engine-out at takeoff, the measured sideslip&#xA;  index is shifted on the PFD by the computed, residual-sideslip value.&#xA;  This index appears in blue, instead of in yellow, and is referred to&#xA;  as the beta target. If the rudder pedal is pressed to center the beta&#xA;  target index, the PF will fly with the residual slip, as required by&#xA;  the engine-out condition. Therefore, the aircraft will fly at a&#xA;  constant heading with ailerons and spoilers close to neutral position.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-17T15:59:44.963" LastActivityDate="2014-02-17T15:59:44.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1772" PostTypeId="1" AcceptedAnswerId="1773" CreationDate="2014-02-16T07:18:04.017" Score="6" ViewCount="1486" Body="&lt;p&gt;I'm fond of ultralight flying and stumbled over the &lt;a href=&quot;http://aerosports.gr/&quot; rel=&quot;nofollow&quot;&gt;SF-1 Archon&lt;/a&gt; site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aerosports.gr/index.php/specifications&quot; rel=&quot;nofollow&quot;&gt;Specifications&lt;/a&gt; for more details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found it very appealing as an ultralight and feel like flying it even though i don't have any prior experience with pusher configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have never heard of the &lt;strong&gt;FFA&lt;/strong&gt; (flying fuselage aircraft) concept so far. My knowledge is rather limited to basic conventional aircraft where the fuselage is considered to neutral by design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone expand on it please?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="1696" LastEditDate="2015-02-17T23:29:42.813" LastActivityDate="2015-10-17T20:49:45.100" Title="What is a flying fuselage aircraft (FFA)?" Tags="&lt;aircraft-design&gt;&lt;amateur-built&gt;&lt;ultralight&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1773" PostTypeId="2" ParentId="1772" CreationDate="2014-02-16T09:07:44.087" Score="4" Body="&lt;p&gt;I found this off the website after some searching:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The advantages of the flying fuselage aircraft (FFA) category,&#xA;  compared to conventional aircraft (CA) category and flying body&#xA;  aircraft (FBA) category, are the following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In conventional aircraft design, the fuselage is aerodynamically&#xA;  neutral and joins only the separate parts of the aircraft. As the&#xA;  wings grow the buoyancy grows as well. In the flying body aircrafts,&#xA;  aerodynamic lift is produced only on the outside of the fuselage and&#xA;  the wings, which comprise a unite body. As the fuselage and wings&#xA;  grow, the generated lift becomes greater. In the flying fuselage&#xA;  aircraft the extra lift is generated from the interior of the fuselage&#xA;  and from the whole aircraft in and out. Thus, maximizing the full&#xA;  extent of the aerodynamic performance of the aircraft. Practically,&#xA;  the new category of the flying fuselage has the following advantages&#xA;  compared to the other categories above. i) because of the greater&#xA;  generated lift ,the aircraft is designed smaller in size, in order to&#xA;  have the same performance as its peers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ii) due to the smaller dimensions of the aircraft, it occupies less&#xA;  space and needs a smaller hangar. (cost reduction).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;iii) the most important advantage is that during the flight in&#xA;  conventional and flying body aircrafts, stability comes only from the&#xA;  main wings dihedral, as well as the size of caudal. The flying&#xA;  fuselage design acts as a funnel and provides extra stability to the&#xA;  aircraft, making the air mass passing through the fuselage in a column&#xA;  of air (air shaft). This is maximizing the stability of the aircraft&#xA;  in all angles and phases of flight. &lt;a href=&quot;http://www.aerosports.gr/index.php/advances&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So what I think what they're trying to say is that the body generates lift as well. It sounds mostly like something like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Blended_wing_body&quot; rel=&quot;nofollow noreferrer&quot;&gt;blended wing body&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting_body&quot; rel=&quot;nofollow noreferrer&quot;&gt;lifting body&lt;/a&gt; in my opinion as a meeting point between a conventional and flying wing aircraft. In any case, the term FFA seems very uncommon and not widely used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aerosports.gr/images/photos_gallery/archonSF1/4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;SF-1 http://www.aerosports.gr/images/photos_gallery/archonSF1/4.jpg&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest similar thing I've found was this &lt;a href=&quot;http://en.wikipedia.org/wiki/NASA_M2-F1&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft&lt;/a&gt;. The F-22 Raptor which it seems to closely mimic is not considered a flying wing nor a blended wing body, and after looking at the fuselage I remained a little unconvinced that it generates substantial lift as a body due to the substantial upper structure and lower structure. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-16T10:49:48.727" LastActivityDate="2014-02-16T10:49:48.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1774" PostTypeId="2" ParentId="1772" CreationDate="2014-02-16T09:29:30.390" Score="3" Body="&lt;p&gt;&quot;Flying Fuselage&quot; is kind of a buzzword for this aircraft, as far as I know. Normally they're called &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting_body&quot; rel=&quot;nofollow&quot;&gt;Lifting Body&lt;/a&gt; aircraft. The point is to make the fuselage generate lift by shaping it somewhat like a wing. The ones on the wiki page generate 75% or more of their lift with the fuselage alone, but they don't &lt;em&gt;have&lt;/em&gt; to; for example, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow&quot;&gt;Piaggio Avanti's&lt;/a&gt; fuselage generates a good bit of lift, allowing its wings to be shorter. An example on the extreme opposite side would be the Apollo crew capsules. If necessary, they could be angled in such a way that the capsule produced lift while it flew through the extreme upper atmosphere. This allowed them to adjust their re-entry trajectory without having to carry fuel or wings.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-16T09:29:30.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1775" PostTypeId="2" ParentId="245" CreationDate="2014-02-16T10:40:23.000" Score="7" Body="&lt;p&gt;Of course it does!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One simple way of looking at this is that piston-powered (well cylinders) are constant-volume engines (ie. 1200cc). As you go higher the air becomes less dense so there is less air mass (and fuel) getting into the engines. If the density becomes half what it was at sea level, you now have in effect a 600cc equivalent engine, etc. Power will be less and less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A turboprop is a constant pressure engine, so as you climb, you kinda need to go faster and faster, but basically you still burn the same amount of air/fuel. You will lose power as you climb in a turboprop,  but that's mostly cause the propeller loses efficiency at the higher speeds you fly higher up. The turbine itself is still as efficient as on the ground.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-02-16T10:40:23.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1776" PostTypeId="1" AcceptedAnswerId="1781" CreationDate="2014-02-16T14:30:38.830" Score="25" ViewCount="49599" Body="&lt;p&gt;Some aircraft come with a Pilot Operating Handbook and some come with an Aircraft Flight Manual.  Why the different name, and is there a difference between them?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2021-05-21T08:27:28.230" Title="What is the difference between a POH and an AFM?" Tags="&lt;afm&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1777" PostTypeId="2" ParentId="1776" CreationDate="2014-02-16T18:00:16.970" Score="-5" Body="&lt;p&gt;The POH is the official book of rules for that specific serial number airplane.  The AFM is the unofficial/generic one for a type of airplane that may or may not match the one it's in.  On occasion you'll run into a book labeled &quot;AFM&quot; that is in fact actually the &quot;POH&quot; (often due to an STC requirement).&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-02-16T18:00:16.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1778" PostTypeId="1" AcceptedAnswerId="1779" CreationDate="2014-02-16T18:04:26.283" Score="13" ViewCount="1143" Body="&lt;p&gt;Written tests are only good for 24 calendar months before they must be applied to a certificate (or lost).  Spin training is a requirement of the flight instructor certificate.  Does the required spin training have the same limitation of life as a written test?  Or, is it like an endorsement where it's good &quot;forever&quot;?&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-02-16T23:12:31.967" Title="How long is spin training good for in the USA?" Tags="&lt;faa-regulations&gt;&lt;spins&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1779" PostTypeId="2" ParentId="1778" CreationDate="2014-02-16T23:12:31.967" Score="13" Body="&lt;p&gt;CFI candidates receive a spin training endorsement with no expiration date. According to &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_61-65e.pdf&quot;&gt;AC 61-65E (the endorsement appendix)&lt;/a&gt;, it should look like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;46. Spin training: section 61.183(i)(1).&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;I certify that &lt;code&gt;(First name, MI, Last name)&lt;/code&gt; has received the required training of section 61.183(i). I have determined that &lt;code&gt;he/she&lt;/code&gt; is competent in instructional skills for training stall awareness, spin entry, spins, and spin recovery procedures.&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;/s/ [date] J. J. Jones 987654321CFI Exp. 12-31-05&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The basis for this is that 61.183 doesn't specify a time period in which the endorsement must be received:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;SID=257acc4699ee7253af775fc7e9492e51&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.8.1.2&quot;&gt;§61.183   Eligibility requirements.&lt;/a&gt;&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;To be eligible for a flight instructor certificate or rating a person must:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;[...]&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;&lt;code&gt;(i)&lt;/code&gt; Accomplish the following for a flight instructor certificate with an airplane or a glider rating:&lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;&lt;code&gt;(1)&lt;/code&gt; Receive a logbook endorsement from an authorized instructor indicating that the applicant is competent and possesses instructional proficiency in stall awareness, spin entry, spins, and spin recovery procedures after providing the applicant with flight training in those training areas in an airplane or glider, as appropriate, that is certificated for spins; and&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-02-16T23:12:31.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1780" PostTypeId="1" AcceptedAnswerId="1782" CreationDate="2014-02-17T00:00:09.587" Score="10" ViewCount="3045" Body="&lt;p&gt;Can full motion simulator training time (FSI) be counted towards the required 100 hours that a part 135 captain is a High Minimum Captain? &lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="69" LastEditDate="2014-02-17T17:35:17.460" LastActivityDate="2014-02-17T17:35:17.460" Title="Does simulator time count as time in type?" Tags="&lt;far-135&gt;&lt;far-61&gt;&lt;flight-simulator&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1781" PostTypeId="2" ParentId="1776" CreationDate="2014-02-17T01:34:11.003" Score="24" Body="&lt;p&gt;Both a POH and an AFM meet the &quot;Operating Limitations&quot; requirement in the &lt;a href=&quot;https://www.acronymfinder.com/Airworthiness-Certificate,-Radio-Station-License,-Registration-Certificate,-Operating-Limitations,-Weight-and-Balance-%28documents-required-to-be-in-an-aircraft-by-the-FAA%29-%28ARROW%29.html&quot; rel=&quot;noreferrer&quot;&gt;ARROW&lt;/a&gt; acronym.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between the two is mainly in length and content: an AFM is usually a thinner document, satisfying the requirements of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.10#14:1.0.1.3.10.7.106&quot; rel=&quot;noreferrer&quot;&gt;FAR 23.1581&lt;/a&gt; and not much else, while a POH contains these required items plus other information like system diagrams (The contents &amp;amp; format of a POH are standardized in &lt;a href=&quot;http://gama.aero/files/gama_specification_1_october_1996_pdf_498ca05388.pdf&quot; rel=&quot;noreferrer&quot;&gt;GAMA's Specification 1&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Parts&lt;/em&gt; of the POH (like the Limitations section) are FAA-Approved, and serve as the AFM, and both documents are typically associated with a specific airframe (by serial number).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A better explanation might be this:&lt;/strong&gt;&lt;br&gt;&#xA;The &lt;code&gt;AFM&lt;/code&gt; is a regulatory document (it's contents are prescribed under the section of the regulations the aircraft was certificated under - Part 23, Part 25, etc). The &lt;code&gt;POH&lt;/code&gt; is a GAMA-defined document whose contents meet the regulatory requirements of an AFM, and present other information in a standardized way so that a pilot can go from a Cessna to a Piper to a Mooney to a Socata and browse the book to learn about the airplane they're about to fly with all the information presented the same way no matter who the manufacturer is.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The other two types of documents you may encounter are an &quot;Owner's Manual&quot; (which usually goes along with a thinner AFM &amp;amp; provides some of the information found in the newer-style POH) and a Pilot Information Manual (PIM) which is a &quot;generic&quot; version of the POH which many pilots buy so they can study the procedures without removing the regulatory document from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/11_phak_ch9.pdf&quot; rel=&quot;noreferrer&quot;&gt;Chapter 9 of the Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; talks a little about the differences between the two documents (and a whole lot of other flight documents).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="679" LastEditDate="2019-03-31T17:26:41.687" LastActivityDate="2019-03-31T17:26:41.687" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="1782" PostTypeId="2" ParentId="1780" CreationDate="2014-02-17T05:06:52.163" Score="7" Body="&lt;p&gt;Unfortunately, no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8b28a2092c4a740f7e85fd0255332482&amp;amp;node=14:3.0.1.1.11.4.3.13&amp;amp;rgn=div8&quot;&gt;135.225 - IFR: Takeoff, approach and landing minimums&lt;/a&gt; (e) requires:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The MDA or DA/DH and visibility landing minimums prescribed in part 97&#xA;  of this chapter or in the operator's operations specifications are&#xA;  increased by 100 feet and 1⁄2 mile respectively, but not to exceed the&#xA;  ceiling and visibility minimums for that airport when used as an&#xA;  alternate airport, &lt;strong&gt;for each pilot in command of a turbine-powered&#xA;  airplane who has not served at least 100 hours as pilot in command in&#xA;  that type of airplane.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So this means that our question becomes:  &lt;strong&gt;&lt;em&gt;Can a pilot log PIC time when &quot;flying&quot; a simulator?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to this question comes from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=8ba6845324e8b8199b52458202355632;rgn=div8;view=text;node=14:2.0.1.1.2.1.1.31;idno=14;cc=ecfr&quot;&gt;61.51 - Pilot logbooks&lt;/a&gt;, where you will notice that none of the bold parts (marked by me) have been met in the situation that you describe.  Generally, PIC time requires you to be PIC of an &lt;strong&gt;&lt;em&gt;aircraft&lt;/em&gt;&lt;/strong&gt;, and does not provide for PIC time when in a simulator unless you are providing instruction:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A sport, recreational, private, commercial, or airline transport&#xA;  pilot may log pilot in command flight time for flights-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When the pilot is the sole manipulator of the controls &lt;strong&gt;of an&#xA;  aircraft&lt;/strong&gt; for which the pilot is rated, or has sport pilot privileges&#xA;  for that category and class of aircraft, if the aircraft class rating&#xA;  is appropriate;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) When the pilot is the sole occupant &lt;strong&gt;in the aircraft&lt;/strong&gt;;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) When the pilot, except for a holder of a sport or recreational&#xA;  pilot certificate, acts as pilot in command &lt;strong&gt;of an aircraft&lt;/strong&gt; for&#xA;  which more than one pilot is required under the type certification of&#xA;  the aircraft or the regulations under which the flight is conducted;&#xA;  or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) When the pilot performs the duties of pilot in command while&#xA;  under the supervision of a qualified pilot in command provided—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) If rated to act as pilot in command of the aircraft, an airline&#xA;  transport pilot may log all flight time while acting as pilot in&#xA;  command &lt;strong&gt;of an operation requiring an airline transport pilot&#xA;  certificate&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) A &lt;strong&gt;certificated flight instructor&lt;/strong&gt; may log pilot in command&#xA;  flight time for all flight time while &lt;strong&gt;serving as the authorized&#xA;  instructor&lt;/strong&gt; in an operation if the instructor is rated to act as&#xA;  pilot in command of that aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) A &lt;strong&gt;student pilot&lt;/strong&gt; may log pilot-in-command time only when the&#xA;  student pilot—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Is the sole occupant of the &lt;strong&gt;aircraft&lt;/strong&gt; or is performing the&#xA;  duties of pilot of command of an airship requiring more than one pilot&#xA;  flight crewmember;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Has a solo flight endorsement as required under §61.87 of this&#xA;  part; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Is undergoing training for a pilot certificate or rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-17T05:06:52.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1783" PostTypeId="2" ParentId="1764" CreationDate="2014-02-17T07:13:44.603" Score="5" Body="&lt;p&gt;I'll add a physical explanation (based on the excellent &lt;a href=&quot;http://www.av8n.com/how/htm/multi.html#sec-1out-coordination&quot;&gt;How It Flies&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust asymmetry generates a torque that will tend to turn the aircraft. To avoid turning, you counter this torque with rudder. The moment of the rudder will balance the moment of the thrust, but the &lt;em&gt;force&lt;/em&gt; generated by the rudder will not be balanced and will cause some slip itself and slip increases drag. So you need to balance the force by adding a bit of sideways lift by banking into the live engine (&quot;raise the dead&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of bank depends on the relative magnitude of the moments and forces involved. If the engines are further apart, the moment of thrust will be larger so rudder will have to produce larger force to counter it and the bank will have to be higher to counter the rudder force. The further aft the rudder is, the less force it needs to produce to yield the same moment and therefore less bank will be needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It follows that the correct bank angle is different for each aircraft. See Lnafziger's answer for examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the slip-skid ball will no longer correspond to slip directly. The ball shows the direction of total weight (gravity plus centrifugal force). Normally it is centred when the weight is correctly balanced by lift, but here the lift is additionally balancing the rudder force, so the ball will be slightly off centre as the weight is directly to the ground when flying straight, but the aircraft is slightly banked.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-02-17T07:13:44.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1784" PostTypeId="1" AcceptedAnswerId="1785" CreationDate="2014-02-17T09:48:30.223" Score="21" ViewCount="6977" Body="&lt;p&gt;I think i've read that the B787 has a common type rating with the B767 and B777. But I also think I've read that pilots are only allowed to fly two types of aircraft at a time... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when they go to fly the 787, do they have to give up one of the their ratings if say they were previously allowed to fly the 767 and 777? Would the same still apply for say a B757 and B767 which have very similar flightdecks? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EASA and FAA perspectives would be appreciated :)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="69" LastEditDate="2014-02-17T18:34:48.497" LastActivityDate="2020-10-12T13:22:05.317" Title="How many type ratings are pilots allowed to hold at once?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;commercial-aviation&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1785" PostTypeId="2" ParentId="1784" CreationDate="2014-02-17T13:41:19.037" Score="29" Body="&lt;p&gt;There is no limit to the number of type ratings that a person can hold. The &lt;a href=&quot;http://www.guinnessworldrecords.com/records-2000/most-faa-aircraft-pilot-type-ratings-by-an-individual/&quot; rel=&quot;noreferrer&quot;&gt;world record&lt;/a&gt; for most type ratings held by an individual currently stands at 105!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For safety reasons, most airlines only allow a pilot to be &lt;em&gt;currently assigned&lt;/em&gt; to two aircraft types at one time so that they don't start to confuse the different airplanes and mix things up. This isn't a regulation though, at least in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your example, those airplanes are the same &lt;strong&gt;type&lt;/strong&gt; so would only count as one of the two that they could be assigned to, but this will vary based on individual airline policy and the complexity of the differences between the actual aircraft involved. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="5568" LastEditDate="2018-02-27T20:50:26.507" LastActivityDate="2018-02-27T20:50:26.507" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1787" PostTypeId="1" AcceptedAnswerId="1788" CreationDate="2014-02-18T12:07:15.663" Score="8" ViewCount="3679" Body="&lt;p&gt;In February 2015, all flights above FL285 in EU airspace are required to have CPDLC/Link 2000+.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However,  I have been told by an avionics provider that some aircraft types are exempt from the requirement.  Where can I find the complete list of exemptions?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-18T12:35:57.570" LastActivityDate="2019-03-12T15:29:02.187" Title="Which airplanes are exempt from Europe's 2015 CPDLC (Link 2000+) requirement?" Tags="&lt;easa-regulations&gt;&lt;avionics&gt;&lt;cpdlc&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1788" PostTypeId="2" ParentId="1787" CreationDate="2014-02-18T12:50:25.503" Score="6" Body="&lt;p&gt;The European Commission has published the &lt;a href=&quot;http://ec.europa.eu/transport/modes/air/single_european_sky/doc/implementing_rules/2014_01_22_2nd_exemption_under_29_2009.pdf&quot; rel=&quot;noreferrer&quot;&gt;Commission Implementing Decision of 9.12.2011&#xA;on exemptions&lt;/a&gt; under Article 14 of &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ%3aL:2009:013:0003:0019%3aEN%3aPDF&quot; rel=&quot;noreferrer&quot;&gt;Commission Regulation (EC) N° 29/2009&lt;/a&gt; (the CPDLC rule)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains the following table of aircraft that are permanently exempted from the CPDLC implementing rule.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;╔════════════════════════════╦════════════╦════════════════╗&#xA;║           Model            ║  ICAO Id   ║ Marketing Name ║&#xA;╠════════════════════════════╬════════════╬════════════════╣&#xA;║ Airbus A318 - 112          ║ A318       ║ A318           ║&#xA;║ Airbus ACJ - 319           ║ A319       ║ ACJ 319        ║&#xA;║ Airbus ACJ - 320           ║ A320       ║ ACJ 320        ║&#xA;║ Airbus A330 – 200/300      ║ A332/A333  ║ A330           ║&#xA;║ Airbus A340 – 200/300      ║ A342/A343/ ║ A340           ║&#xA;║              /500/600      ║ A345/A346  ║                ║&#xA;║ British Aeropace AVRO      ║ RJ1H       ║ AVRO RJ        ║&#xA;║     RJ100                  ║            ║                ║&#xA;║ Dassault Falcon 10 and     ║ FA10       ║ Falcon 10      ║&#xA;║     Falcon 100             ║            ║                ║&#xA;║ Dassault Fan Jet Falcon    ║ FA20       ║ Falcon 20      ║&#xA;║     Basic and              ║            ║                ║&#xA;║     Serie C/D/E/F/G        ║            ║                ║&#xA;║ Dassault Mystère-Falcon    ║ FA20       ║ Falcon 20      ║&#xA;║     200, 20GF and 20-      ║            ║                ║&#xA;║     C5/D5/E5/F5            ║            ║                ║&#xA;║ Dassault Falcon 50EX and   ║ FA50       ║ Falcon 50      ║&#xA;║     Mystère Falcon 50      ║            ║                ║&#xA;║ Dassault Falcon 900, 900B, ║ F900       ║ Falcon 900     ║&#xA;║     900C and 900 EX        ║            ║                ║&#xA;║ Dassault Falcon 2000       ║ F2TH       ║ Falcon 2000    ║&#xA;║     and 2000EX             ║            ║                ║&#xA;║ Gulfstream GIV             ║ GLF4       ║ Gulfstream IV  ║&#xA;║     and GIV-SP             ║            ║                ║&#xA;║ Gulfstream G300            ║ GLF4       ║ Gulfstream 300 ║&#xA;║ Gulfstream G400            ║ GLF4       ║ Gulfstream 400 ║&#xA;║ Gulfstream GV              ║ GLF5       ║ Gulfstream V   ║&#xA;║ McDonnell Douglas MD11-F   ║ MD11       ║ MD-11          ║&#xA;║      and MD11-CF           ║            ║                ║&#xA;╚════════════════════════════╩════════════╩════════════════╝&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-02-18T12:50:25.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1789" PostTypeId="1" AcceptedAnswerId="1791" CreationDate="2014-02-18T14:37:27.837" Score="13" ViewCount="1314" Body="&lt;p&gt;I'm wondering if it's possible to forward slip a large commercial aircraft, like the A320 or even B777, and if so:  is effective or useful, since most small aircraft which I gather do it have no spoilers for instance which large aircraft do?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="774" LastEditDate="2014-02-18T18:59:32.570" LastActivityDate="2019-03-21T20:16:36.397" Title="Is it possible and effective to perform a forward slip in a large commercial jet?" Tags="&lt;aircraft-performance&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1790" PostTypeId="1" AcceptedAnswerId="1792" CreationDate="2014-02-18T15:01:23.400" Score="27" ViewCount="20070" Body="&lt;p&gt;I have heard that some aircraft that do not have an APU can run an engine in &quot;Hotel Mode&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is hotel mode? Are there any advantages to having it instead of an APU?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="1696" LastEditDate="2015-11-30T18:41:31.567" LastActivityDate="2019-01-03T01:07:15.337" Title="What is &quot;Hotel Mode&quot; on a turboprop engine?" Tags="&lt;turboprop&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1791" PostTypeId="2" ParentId="1789" CreationDate="2014-02-18T15:08:29.113" Score="14" Body="&lt;p&gt;It's it possible?  Yes, you would do it the same way as in any other airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it effective?  Yes, just look at all of the fuselage area that is exposed to the relative wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it useful?  Not really.  With all of the other drag devices, you shouldn't really need it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it recommended?  You would have to check the AFM.  I looked in the &lt;a href=&quot;http://www.737ng.co.uk/A320%20321%20FCTM%20Flight%20Crew%20Training%20Manual.pdf&quot; rel=&quot;noreferrer&quot;&gt;A320 Flight Crew Training Manual&lt;/a&gt; and there is no limitation against it, but if you need to slip then that's a strong indication of poor planning and an unstabilized approach which would require a go around.  Even at higher altitudes, it isn't very comfortable for the passengers!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-19T00:36:06.617" LastActivityDate="2014-02-19T00:36:06.617" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1792" PostTypeId="2" ParentId="1790" CreationDate="2014-02-18T15:11:41.810" Score="31" Body="&lt;p&gt;&lt;strong&gt;Hotel mode&lt;/strong&gt; is a feature on ATR 42/72 turboprops replacing an APU by locking the right-hand #2 engine (PW100) with a 'propeller brake' while allowing the turbine, and therefore also the generator, to run, providing electrical power and bleed air.&lt;/p&gt;&#xA;&lt;p&gt;ATR describes this as the following:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The propeller brake is fitted on a countershaft on the RH engine reduction gearbox in order to stop the propeller (and the power turbine)&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;HP (High Pressure) spool drives the DC generator.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Bleed pressure is available downstream the HP compressor and supplies both packs.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This picture should give you sort-of an idea of how it works:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/crB0C.jpg&quot; alt=&quot;hotel-mode&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;If I gather correctly, the propeller drive shaft is locked, and the (HP) compressor shaft is free to run.&lt;/p&gt;&#xA;&lt;p&gt;Here's another pic of a PW100 engine:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i162.photobucket.com/albums/t277/stickshaker_photos/Air%20Show/IMG_0849edit.jpg&quot; alt=&quot;engine&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Hotel Mode seems to be generally disliked for a number of reasons:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's very loud, especially if you're lifting baggage next to it&lt;/li&gt;&#xA;&lt;li&gt;It consumes a lot of fuel, since you're running a full engine.&lt;/li&gt;&#xA;&lt;li&gt;It could be dangerous if the propeller brake is in poor condition and suddenly loses its grip.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This configuration is rare, if not unique. The rival Dash-8 has a separate APU, as does the Saab 2000. It was an optional feature on the Fokker 50. The smaller Jetstream 41 only has a battery.&lt;/p&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/ATR72-POWER_PLANT.html&quot; rel=&quot;noreferrer&quot;&gt;SmartCockpit ATR-72 documents&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-01-02T19:05:08.650" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="1793" PostTypeId="1" AcceptedAnswerId="1796" CreationDate="2014-02-18T15:53:02.907" Score="28" ViewCount="15687" Body="&lt;p&gt;By my understanding, the Mach Number at a given altitude is calculated by dividing IAS by the speed of sound at that altitude. So how is this speed of sound calculated to display the Mach Number on the Mach Meter? Does the Mach Meter share the same pitot tube used to calculate airspeed?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="69" LastEditDate="2014-02-18T21:28:17.883" LastActivityDate="2019-08-14T16:20:35.083" Title="How does a Mach Meter determine the speed of sound at a given altitude?" Tags="&lt;flight-instruments&gt;&lt;airspeed&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1794" PostTypeId="2" ParentId="1793" CreationDate="2014-02-18T16:08:09.930" Score="23" Body="&lt;p&gt;An (analog) machmeter looks something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/l7F9d.jpg&quot; alt=&quot;machmeter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's more like an more complex version of the airspeed indicator, in this case correcting for the altitude in the process. That being said, I found this extract apparently from an FAA publication:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some older mechanical Machmeters not driven from an air data computer use an altitude aneroid inside the instrument that converts pitot-static pressure into Mach number. These systems assume that the temperature at any altitude is standard; therefore, the indicated Mach number is inaccurate whenever the temperature deviates from standard. These systems are called indicated Machmeters. Modern electronic Machmeters use information from an air data computer system to correct for temperature errors. These systems display true Mach number.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most systems today use more detailed data from sensors to give a correct value through a variety of (complex) calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A little more discussion is &lt;a href=&quot;http://www.pprune.org/tech-log/397424-mach-number.html&quot; rel=&quot;noreferrer&quot;&gt;available on PPruNe&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Side note: Speed of sound ($a$) itself is &lt;em&gt;solely determined by temperature&lt;/em&gt; (that being said, you are able to determine it from pressure, as pressure is a function of temperature) hence the problem with the analog system above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For air:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a=\sqrt{R{\gamma}T}~m/s$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R=287$  Specific Gas constant [dimensionless]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\gamma=1.4$  Specific heat ratio [dimensionless] &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T=$ Absolute temperature [K]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that you're reading off indicated airspeed [IAS] in knots in the cockpit, which is not the same as True airspeed [TAS] converted to m/s, in case you're trying to work out your mach speed manually ($M=\frac{TAS}{a}$)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For use without knowledge of airspeed &amp;amp; temperature, &lt;a href=&quot;http://en.wikipedia.org/wiki/Machmeter&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia gives the following formula&lt;/a&gt; for subsonic flows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$M=\sqrt{5((\frac{P_T}{P}+1)^\frac27-1)}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P_T=$ Total Pressure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P=$ Static Pressure&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-04-17T01:46:56.913" LastActivityDate="2014-04-17T01:46:56.913" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1795" PostTypeId="2" ParentId="1760" CreationDate="2014-02-18T18:09:05.693" Score="7" Body="&lt;p&gt;As SSumner pointed out, &lt;a href=&quot;http://www.faa.gov/regulations_policies/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA produces all kinds of paper&lt;/a&gt; - some of which is &quot;regulatory&quot; and/or have legal force, and some of which isn't.  I won't go into all of the specific document categories, but I'll talk about a few that most of us will find interesting.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Handbooks and Manuals&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;The FAA actually publishes full-length books, if you know where to look!&lt;br&gt;&#xA;The FAA has written books on &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying an airplane&lt;/a&gt;,  &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/FAA-H-8083-11.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying balloons&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/risk_management_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;risk management&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/faa-h-8083-19A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;buying &amp;amp; owning an airplane&lt;/a&gt;, and a whole bunch of other topics which provide broad information that you can use to familiarize yourself with a topic.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Advisory Circulars&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;Advisory Circulars (ACs) are the FAA's way of explaining their regulations.&lt;br&gt;&#xA;They're broken down into sections which generally match up with the FARs they're interpreting.  Some ACs may rival the lengths of handbooks, but they are much more narrowly focused, generally dealing with a single topic and often much easier to understand than the legislation they're interpreting.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/airworthiness_directives/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Airworthiness Directives&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;When an unsafe condition is identified in an aircraft or component which requires action the FAA can issue an Airworthiness Directive (AD), requiring that specific actions be taken.&lt;br&gt;&#xA;Often the required action is compliance with a manufacturer's Service Bulletin (or compliance with a service bulletin is also an acceptable method of compliance with an AD).&lt;br&gt;&#xA;There are also &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Special Airworthiness Information Bulletins&lt;/a&gt; (SAIBs), which are like &quot;Mini-ADs&quot;: The FAA is calling operators' and mechanics' attention to something which may not merit an AD. SAIBs are informational - you don't have to comply with them - but it's certainly a good idea to read them and pay attention to the things they're highlighting. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.list/documentType/order&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Orders&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;An &quot;Order&quot; describes procedures used by the FAA. For example, &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1019803&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7110.65U&lt;/a&gt; describes various aspects of how ATC works. &#xA;Procedures described in Orders may be modified by Notices.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.list/documentType/notice&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Notices&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;A &quot;Notice&quot; is just an agency's way of saying &quot;Yo! Pay attention! Something's happening!&quot;&lt;br&gt;&#xA;Your question seems generally concerned with internal notices which I linked to in the title. These generally modify Orders, like &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.659_Non-Intersecting_Converging_Runway_Operations_(90-day_extension).pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;.&lt;br&gt;&#xA;The FAA can also issue &quot;Public Notices&quot; about &lt;a href=&quot;http://www.faasafety.gov/spans/noticeView.aspx?nid=5160&quot; rel=&quot;nofollow noreferrer&quot;&gt;changes that affect airmen and the   general public&lt;/a&gt;, or pretty much any other topic they'd like.  Public Notices are published on faa.gov as well, but the easiest place to find those is through the FAA Safety Team's &lt;a href=&quot;http://www.faasafety.gov/spans/notices_public.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;SPANS system&lt;/a&gt; which is searchable and has a much nicer interface than digging through the FAA site by region.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for whether the non-legislative documents have legal force the answer is a very well-qualified &quot;maybe&quot;.  Some certainly have the force of &lt;em&gt;regulation&lt;/em&gt; – Airworthiness Directives being the most obvious – and for our purposes I think that's what you're really concerned with, because the &lt;em&gt;law&lt;/em&gt; says you have to comply with the &lt;em&gt;regulations&lt;/em&gt;.&lt;br&gt;&#xA;Orders and Notices are similarly &quot;regulatory&quot; for the agency: The FAA has to comply with its own orders, so ATC has to be operated the way JO 7110 says it's to be operated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For stuff like ACs, Handbooks, etc. we &lt;a href=&quot;http://chat.stackexchange.com/transcript/message/13639545#13639545&quot;&gt;discussed this in chat a while back&lt;/a&gt; talking about the answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1593/what-is-the-8900-that-the-faa-uses-for-guidance&quot;&gt;FAA Order 8900 and the FSMS&lt;/a&gt; - the gist of it is that the non-legislative documents the FAA produces are generally interpretations and guidance, but they are &lt;strong&gt;&quot;effectively regulatory&quot;&lt;/strong&gt; in that if you go against them you need to have an &lt;em&gt;excellent&lt;/em&gt; reason for doing so, and be prepared to back it up with appropriate justification and evidence if asked. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a classic example, alterations to aircraft are expected to be performed in accordance with manufacturer's maintenance procedures, or &quot;other methods, techniques, or practices acceptable to the Administrator&quot; which are described in AC 43.13 (&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2043.13-2B.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;43.13-2B&lt;/a&gt; deals with light, non-pressurized aircraft and is an interesting read).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mechanic doesn't &lt;strong&gt;&lt;em&gt;have&lt;/em&gt;&lt;/strong&gt; to comply with the guidance in AC 43.13, but if a mechanic were to modify an aircraft without conforming to that guidance they would need to supply supporting documentation as to why their work is acceptable, such as a statement from a Designated Engineering Representative, otherwise the FAA could deem the work &quot;unacceptable&quot; (and from a liability standpoint, the mechanic could wind up in serious trouble should something go wrong with the aircraft as a result of that work).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-02-18T18:09:05.693" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1796" PostTypeId="2" ParentId="1793" CreationDate="2014-02-18T19:37:52.647" Score="22" Body="&lt;p&gt;Most modern jets use an Air Data Computer (ADC) to calculate (among other things) Mach Number.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://thumbs1.ebaystatic.com/d/l225/m/mQ1FlptDNFg2k6xAtImkVtQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fELpW.jpg&quot; alt=&quot;ADC&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Air Data Computer&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An ADC is simply a computer which accepts measurements of atmospheric data to calculate various flight related data.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical ADC may be connected to$^1$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Inputs&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Static System Pressure&lt;/li&gt;&#xA;&lt;li&gt;Pitot Pressure&lt;/li&gt;&#xA;&lt;li&gt;Total Air Temperature (TAT)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Outputs (Calculated)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pressure Altitude&lt;/li&gt;&#xA;&lt;li&gt;Baro-Corrected Altitude&lt;/li&gt;&#xA;&lt;li&gt;Vertical Speed&lt;/li&gt;&#xA;&lt;li&gt;Mach Number&lt;/li&gt;&#xA;&lt;li&gt;Total Air Temperature&lt;/li&gt;&#xA;&lt;li&gt;Calibrated Airspeed&lt;/li&gt;&#xA;&lt;li&gt;True Airspeed&lt;/li&gt;&#xA;&lt;li&gt;Digitized Pressure Altitude (Gillham) &lt;/li&gt;&#xA;&lt;li&gt;Altitude Hold&lt;/li&gt;&#xA;&lt;li&gt;Airspeed Hold&lt;/li&gt;&#xA;&lt;li&gt;Mach Hold&lt;/li&gt;&#xA;&lt;li&gt;Flight Control Gain Scheduling. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each of the inputs and outputs may be analog or digital depending on the design of the system, and are used for many purposes throughout the airplane.  Each output is a purely calculated value based on the various input measurements and data stored within the unit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question about the pitot source for the Mach Meter: Yes, they use the same pitot and static sources as the airspeed indicator.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of mechanical instruments, they are both connected directly to the pitot static system.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of an ADC, the pitot static system is connected directly to the ADC and then electrical signals communicate the airspeed and mach number to the electric airspeed indicator and mach meter (or EFIS), which no longer require actual pitot static connections.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;The Math&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;A simplified example for the Mach Number calculation$^2$ would be based on the pressure inputs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Mach~number=5((PT/PS+1)^{0.2857}–1)^\frac12$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$PT$ = Total Pressure&lt;br&gt;&#xA;$PS$ = Static Pressure &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual calculation makes corrections to the pressure data to compensate for installation errors and nonlinear sensor readings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that it doesn't actually calculate the (local) speed of sound (LSS) in order to determine the current mach number, but with the TAT input and the calculated mach number, it &lt;em&gt;could&lt;/em&gt; calculate it by calculating the outside air temperature (OAT/SAT) first:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$SAT=\frac{TAT}{1+0.2\times{Mach}^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$LSS=38.945\sqrt{SAT}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, let's say that the TAT is -36C (237.16K) and we are flying Mach 0.80:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$SAT=\frac{237.16}{1+0.2\times0.8^2}=\frac{237.16}{1.128}=210.25°K=-63°C$$  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$LSS=38.945\sqrt{210.25}=38.945\times14.5=564.70knots$$  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, these are simplified formulas because the actual ones would consider sensor error, etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;$^1$ List of inputs and outputs obtained from &lt;a href=&quot;http://techaidproducts.com/PDFs/Air%20Data%20Computers.pdf&quot; rel=&quot;noreferrer&quot;&gt;Air Data Computers&lt;/a&gt;.&lt;br&gt;&#xA;$^2$ Formula from &lt;a href=&quot;http://www.spaceagecontrol.com/Main/TATSensorOperationAndEquations&quot; rel=&quot;noreferrer&quot;&gt;TAT Sensor Operation and Equations&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-18T03:28:38.357" LastActivityDate="2014-04-18T03:28:38.357" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1797" PostTypeId="2" ParentId="1793" CreationDate="2014-02-18T20:55:46.047" Score="10" Body="&lt;p&gt;A Machmeter does not determine the speed of sound. It doesn't even need to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Mach~Number=\frac{P_T-P_S}{P_S}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mach number is simply the ratio between total pressure minus static pressure, divided by the static pressure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is why:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Mach~Number=\frac{TAS}{LSS}$$  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Mach number is true airspeed versus the local speed of sound&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$TAS=IAS\sqrt{T}\div\sqrt{P}\div16.97$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Converting indicated speed to true speed, we need to multiply with the square root of absolute temperature (in °K)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$LSS=38.94\sqrt{T}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the local speed of sound is directly proportional with the square root of absolute temperature (in °K)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you divide $TAS=IAS\sqrt{T}\div\sqrt{P}\div16.97$ by $LSS=38.94\sqrt{T}$, the $\sqrt{T}$ will cancel eachother out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Mach~Number=\frac{IAS}{\sqrt{P}x}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IAS we already have, it's dynamic pressure minus static pressure, and $P$ is just static pressure, or, like I said in the beginning:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Mach~Number=\frac{P_T-P_S}{P_S}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See, no thermometer... only dynamic and static pressure.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="97" LastEditDate="2014-04-18T03:24:59.423" LastActivityDate="2014-04-18T03:24:59.423" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1798" PostTypeId="1" AcceptedAnswerId="12652" CreationDate="2014-02-19T00:08:51.527" Score="24" ViewCount="4236" Body="&lt;p&gt;I learned in my intro to engineering class at my college that 5th gen fighters (which are stealth aircraft) are designed with similar angles to evade radar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this true?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, does the angle matter?  Many of these modern fighters looks to have very similar angles (no pun intended).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1MAhQ.jpg&quot; alt=&quot;Sukhoi PAK FA&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="1696" LastEditDate="2015-02-13T20:29:56.960" LastActivityDate="2015-02-15T18:07:22.393" Title="Do similar angles on a plane make it more stealthy?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;stealth&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1799" PostTypeId="2" ParentId="1798" CreationDate="2014-02-19T01:16:04.717" Score="18" Body="&lt;p&gt;The angle matters because radar works kind of like a mirror. Imagine holding a mirror out in front of you. If you start to twist it in any direction, you reach a certain point where the light coming off of you is no longer bounced back into your eyes, but is reflected off in another direction. Radar however cannot ever be completely reflected away, but this same principle allows a significant portion of the radar's energy to be deflected off in a useless direction, instead of back toward the dish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angles are similar because that angle was determined to have the smallest radar signature. So it makes sense that every other facet on the same (geometric) plane would be at the same angle. This means that the radar's energy is directed away in a very specific direction (away from the source), rather than a bunch of different angles (that would be more likely to return the energy to the source).&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-02-19T01:16:04.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1800" PostTypeId="2" ParentId="1464" CreationDate="2014-02-19T01:51:03.100" Score="7" Body="&lt;p&gt;Although this is obviously not real-world, &lt;a href=&quot;http://www.vatsim.net&quot; rel=&quot;noreferrer&quot;&gt;VATSIM&lt;/a&gt; does try to mimic it as closely as possible.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.vatsim-uk.co.uk/download/fetch/?downloadID=00119&quot; rel=&quot;noreferrer&quot;&gt;London Luton's VMATs&lt;/a&gt; has this to say:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;3.2.6 Land after procedures&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Normally, only one aircraft is permitted to land or take-off on the runway in use at any one time. However, when the traffic sequence is two successive landing aircraft, the second one may be allowed to land before the first one has cleared the runway in use, providing that:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It is during daylight hours&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The preceding aircraft does not intend to backtrack in order to vacate&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There is no evidence that braking action may be adversely affected&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The second aircraft will be able to see the first aircraft clearly and continuously until it is clear of the runway&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The second aircraft has been warned&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In place of the standard &amp;quot;cleared to land&amp;quot;, the instruction &amp;quot;Land after (first aircraft type)&amp;quot;. The responsibility for ensuring separation then lies with the pilot of the second aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-19T01:51:03.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1801" PostTypeId="1" AcceptedAnswerId="1804" CreationDate="2014-02-19T02:13:24.333" Score="15" ViewCount="2297" Body="&lt;p&gt;As technology becomes more advance airplanes are becoming less and less stable.  In flight school I learned that it's dangerous to load a Cessna out of it's CG range, and now in college (for aerospace engineering) I'm learning about modern fighters and their fundamentally unstable designs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of these unstable aircraft are supermaneuverable but rely on computers to fly them more than the human pilot in the cockpit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure that these airplanes are thoroughly checked before every flight to make sure the computer systems will perform accordingly, but in the event of a failure what kind of side affects might a pilot experience?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two conditions I can think of are&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;No computer aid, but the control surfaces are still &quot;responsive&quot;&lt;/li&gt;&#xA;&lt;li&gt;The pilot loses all control of the aircraft and none of the inputs work.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KateE.jpg&quot; alt=&quot;X-29&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="1696" LastEditDate="2015-02-19T20:45:31.407" LastActivityDate="2021-03-18T07:00:39.917" Title="How do &quot;fundamentally unstable&quot; aircraft deal with the risk of computer failure?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;aircraft-limitations&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1802" PostTypeId="1" AcceptedAnswerId="1805" CreationDate="2014-02-19T02:22:03.430" Score="88" ViewCount="23577" Body="&lt;p&gt;With the recent advances in drone and remote control technology, why are there still commercial and military pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that there can be some serious tactical advantages to human pilots in military operations, but for patrol and commercial flights what are the advantages of a human pilot in the aircraft as opposed to a drone or a remotely controlled airplane?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="69" LastEditDate="2014-02-19T07:22:57.047" LastActivityDate="2017-06-29T21:59:59.313" Title="Why do we still use pilots to fly airplanes?" Tags="&lt;autopilot&gt;&lt;unmanned-aerial-vehicle&gt;&lt;pilots&gt;" AnswerCount="6" CommentCount="16" FavoriteCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="1803" PostTypeId="1" CreationDate="2014-02-19T02:28:51.157" Score="3" ViewCount="1239" Body="&lt;p&gt;There are more experimental class aircraft in the USA than any other.  That being said, what type of requirements does an experimental aircraft have to meet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, are there ways around certain regulations?  For example, the guy in the picture below was battling with the FAA so they would let him fly his jet pack in the USA over the grand canyon, which they originally said no to, but they eventually let him - is this because he is &quot;famous&quot; and therefore has less rules he needs to follow?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fD3H3.jpg&quot; alt=&quot;Guy flying on jet wing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="1696" LastEditDate="2015-03-02T22:46:29.623" LastActivityDate="2015-03-02T22:46:29.623" Title="What are the US regulations governing experimental aircraft?" Tags="&lt;faa-regulations&gt;&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1804" PostTypeId="2" ParentId="1801" CreationDate="2014-02-19T02:36:14.827" Score="19" Body="&lt;p&gt;&quot;fundamentally unstable&quot; but über-responsive aircraft have multiple computers that take a vote on everything the pilot wants to do. If one computer fails the others will take over. There is often no direct connection between the control column and the flight surfaces so the &quot;no computer aid&quot; situation would be the same as #2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If everything fails, the checklist is rather short: eject &lt;em&gt;immediately&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="891" LastActivityDate="2014-02-19T02:36:14.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1805" PostTypeId="2" ParentId="1802" CreationDate="2014-02-19T03:08:53.813" Score="119" Body="&lt;p&gt;That's a good question, and brings up a joke that many pilots know well:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;What's going to be in the cockpit of the future?&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;A dog and a pilot.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;A dog?  Why a dog?&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Well, the dog is there to keep the pilot from touching anything.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Ummm, why have the pilot then?&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Well, someone has to feed the dog! &quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Technology has improved to the point where airplanes can pretty much fly and even land themselves.  They are even getting pretty good at handling &quot;normal&quot; emergencies like engine failures and depressurizations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where pilots really shine though are the type of abnormal and emergency situations that aren't &quot;in the book&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot;&gt;When an engine flies apart and shreds the hydraulic lines on all three redundant hydraulic systems&lt;/a&gt;, a computer will be out of options because it was never programmed to handle that (because it was considered &quot;virtually impossible&quot; when it was designed).  A pilot on the other hand can analyze and experiment until he finds enough of a solution to keep the airplane in the air as he works through other issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a total electrical failure, the computers won't be much good.  Sure, you can design redundant systems and make it so that it &quot;can never happen&quot;, but what about &lt;strong&gt;when&lt;/strong&gt; it does?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also all of the little things that a pilot is constantly making decisions on how to handle.  Some examples could include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can the airplane fly with a particular feature inoperative?  &lt;/li&gt;&#xA;&lt;li&gt;What about multiple features inoperative?  &lt;/li&gt;&#xA;&lt;li&gt;How do they interact with each other?  &lt;/li&gt;&#xA;&lt;li&gt;What do you do when the passengers take too long to board and you are going to miss your departure slot?  &lt;/li&gt;&#xA;&lt;li&gt;What do you do when the ground crew forgets to close a door?  &lt;/li&gt;&#xA;&lt;li&gt;What about when the tug driver doesn't push you back &lt;em&gt;quite&lt;/em&gt; far enough?  &lt;/li&gt;&#xA;&lt;li&gt;Or ATC wants to change you to a different runway?  &lt;/li&gt;&#xA;&lt;li&gt;Or you &lt;strong&gt;ask&lt;/strong&gt; ATC to change you to a different runway because it might save a few minutes and that will keep you from having to deice again?  &lt;/li&gt;&#xA;&lt;li&gt;Or another airplane unexpectedly pulls out in front of you while taxiing?  &lt;/li&gt;&#xA;&lt;li&gt;A pilot can see &quot;ugly&quot; clouds off the end of the runway and decide that it would be better to wait a bit before taking off.  &lt;/li&gt;&#xA;&lt;li&gt;What happens when a flock of birds suddenly appears during the takeoff roll?  &lt;/li&gt;&#xA;&lt;li&gt;What happens when a passenger gets sick or unruly?  &lt;/li&gt;&#xA;&lt;li&gt;When do you need to divert and when can you continue? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On a typical flight, a pilot will make hundreds of small decisions that can make a big difference in the flight.  Any one of these (or one of the tens or hundreds of thousands of other things that could happen) could trip up a computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot is also there as the &quot;final authority&quot;.  If a hacker were to somehow hack into the automated systems, a pilot can always disconnect them and fly the airplane manually.  He can turn off systems, he can be...  Well, the pilot can be creative and a computer can only do what it was programmed to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right now when a drone crashes it isn't such a big deal because &lt;em&gt;nobody was on board&lt;/em&gt;.  If an airliner with a load full of paying passengers crashes it is a &lt;strong&gt;big&lt;/strong&gt; deal.  Even just one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of these problems can be overcome.  Some of them already have been.  Some of them may never be fully handled in an automatic way but maybe we could still do automated flights with an acceptable level of safety.  Some automation is actually &lt;strong&gt;better&lt;/strong&gt; than some pilots in certain areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the biggest reason that we don't have fully automated passenger airplanes is because the general public feels comforted by a &lt;strong&gt;&lt;em&gt;person&lt;/em&gt;&lt;/strong&gt; being up front who can take over and carry them to safety if needed.  Even if the technology were 100% ready for automated passenger flights, I think that the number of people willing to purchase a ticket would be so low that it would be financially unfeasible for an airline to deploy it.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-20T09:31:06.313" LastActivityDate="2014-02-20T09:31:06.313" CommentCount="30" ContentLicense="CC BY-SA 3.0" />
  <row Id="1806" PostTypeId="2" ParentId="1748" CreationDate="2014-02-19T04:33:11.900" Score="9" Body="&lt;p&gt;The Australian Transport Safety Bureau did a report titled:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.atsb.gov.au/publications/2007/ar-2007-043%282%29.aspx&quot;&gt;Amateur-built aircraft Part 2: Analysis of accidents involving VH-registered non-factory-built aeroplanes 1988-2010&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This report specifically covers this and found that the accident rate was three times higher in kit built -vs- similar factory build aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What did this report do&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The ATSB investigated the safety history of amateur-built aircraft in&#xA;  Australia through analysis of accident data held in the ATSB’s&#xA;  occurrence database from 1988 to 2010. Comparisons were made between&#xA;  accidents involving amateur-built aircraft and those involving similar&#xA;  factory-built aircraft to help identify whether the rate and types of&#xA;  accidents differed between these two groups of aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;What the ATSB found&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Amateur-built aircraft had an accident rate three times higher than&#xA;  comparable factory-built certified aircraft conducting similar flight&#xA;  operations between 1988 and 2010. The fatal and serious injury&#xA;  accident rate was over five times higher in amateur-built aircraft, in&#xA;  particular due to relatively more serious injury accidents. The pilots&#xA;  of amateur-built aircraft involved in accidents were significantly&#xA;  more experienced overall than factory-built aircraft accident pilots.&#xA;  However, they were significantly less experienced on the aircraft type&#xA;  that they were flying at the time of the accident.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Over half of the accidents were precipitated by mechanical events,&#xA;  which were mainly complete or partial engine failures. Following the&#xA;  amateur-built phase one test period, mechanical failures were still&#xA;  significantly more common when compared with factory-built aircraft. A&#xA;  quarter of accidents were from loss of aircraft control. Structural&#xA;  failures were not common precursors in amateur-built aircraft.&#xA;  Collision with terrain and forced landing accidents were more frequent&#xA;  in amateur-built aircraft. Collisions with terrain, hard landings, and&#xA;  runway excursions were more likely to result in a serious injury from&#xA;  an amateur-built aircraft accident than for factory-built accidents.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the EAA says that homebuilt aircraft have an accident rate of less than 1% higher than the general aviation fleet in their &lt;a href=&quot;http://www.eaa.org/homebuilders/faq.asp&quot;&gt;FAQ&lt;/a&gt;, but this didn't compare homebuilt to factory built in similar models:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How Safe Are Amateur-Built/Homebuilt Aircraft?&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Studies by FAA and the National Transportation Safety Board (NTSB)&#xA;  show that Amateur-Built/Homebuilt aircraft have an accident rate less&#xA;  than one percentage point higher than the general aviation fleet. In&#xA;  fact, the accident rate for Amateur-Built/homebuilt aircraft is&#xA;  dropping. The total number of registered homebuilt aircraft is&#xA;  increasing by about 1,000 per year, while the total number of&#xA;  accidents has stayed virtually the same. Another good barometer of&#xA;  safety is insurance rates. Companies that insure both homebuilts and&#xA;  production aircraft charge about the same rates for owners of either&#xA;  type of airplane. That indicates a similar level of risk.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-19T04:33:11.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1807" PostTypeId="1" AcceptedAnswerId="1821" CreationDate="2014-02-19T06:51:14.447" Score="37" ViewCount="139221" Body="&lt;p&gt;Reading various reports including number of flight hours of the pilots I always wonder how it relates to years of service. In most professions, people work 40 hours a week, which gives around 1900 hours a year (assuming 4-5 weeks vacation as is usual in Europe). But pilots seem to have much fewer &lt;em&gt;flight&lt;/em&gt; hours. I even read that in certain military operation the norm was 750 hours in a year. But that was difficult military operation and I haven't seen any number for common airline operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how many flight hours is usual for full-time airline pilot to log in a year? And what does he do in the rest of his duty time? Or does he have less duty time than the usual 40 hours a week?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="258" LastEditDate="2016-01-29T20:36:02.050" LastActivityDate="2017-07-29T11:28:01.573" Title="What is common number of flight hours a year for an airline pilot?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1808" PostTypeId="2" ParentId="1807" CreationDate="2014-02-19T07:16:40.020" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1e483077c0bff7e356d8aece28712f40&amp;amp;node=14:3.0.1.1.7.17.3.2&amp;amp;rgn=div8&quot;&gt;14 CFR 121&lt;/a&gt; contains the legal limit for flight time for airline pilots in the US (you didn't specify whose regulations you were interested in):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No certificate holder conducting domestic operations may schedule&#xA;  any flight crewmember and no flight crewmember may accept an&#xA;  assignment for flight time in scheduled air transportation or in other&#xA;  commercial flying if that crewmember's total flight time in all&#xA;  commercial flying will exceed—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) 1,000 hours in any calendar year;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) 100 hours in any calendar month;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) 30 hours in any 7 consecutive days;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That gives you a rough idea of what the airlines would like every pilot to fly in order to best utilize them.  The actual number of hours flown however depends on a lot of things, including the lines that the pilots bid on and whether or not they pick up any extra trips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this appears less than a &quot;typical&quot; job, keep in mind, this limit only applies to &lt;strong&gt;flight time&lt;/strong&gt; (which oddly enough includes time taxiing the airplane).  The crew will spend additional time before the trip, between each leg, and at the end of the trip taking care of things like pre-flights and post-flights, getting clearances, doing paperwork, etc.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-02-20T03:17:12.690" LastActivityDate="2014-02-20T03:17:12.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1809" PostTypeId="1" AcceptedAnswerId="1812" CreationDate="2014-02-19T08:28:43.077" Score="2" ViewCount="2549" Body="&lt;p&gt;We know that most of the plane accidents and deaths result from the explosion of fuel tanks in the planes, like when two planes collide, or when the plane falls on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the advent of technology, i wonder whether it is possible to prevent the fuel explosion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can this be done by evaporating the fuel in the planes just before the collision?&#xA;Or use a solid architecture encapsulating the fuel tanks in the planes, such that the fuel is not set to fire?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What research has been done in this field and if so what were the findings?&lt;/p&gt;&#xA;" OwnerUserId="896" LastEditorUserId="19" LastEditDate="2014-02-19T09:52:59.350" LastActivityDate="2014-02-19T12:34:30.333" Title="Is it possible to prevent plane accidents due to fuel explosion?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;accidents&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1810" PostTypeId="2" ParentId="1809" CreationDate="2014-02-19T09:34:37.093" Score="10" Body="&lt;p&gt;Evaporating/misting is the primary cause of the fireball and adding to that just makes the fireball larger and takes a lot of energy that just isn't available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA tried to study anti misting measures with their &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_Impact_Demonstration&quot;&gt;controlled impact demonstration&lt;/a&gt; once using an additive that made the fuel more syrup-like so it wouldn't spray as much; they essentially made napalm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A solid structure to contain fuel may sound promising but that would add a lot of weight and is not bulletproof (designing a oblong shape that will survive an 800 km/h impact into concrete is far from trivial).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One option would be to cut the engine+all power and force cool it down using the extinguishing system so there isn't an ignition source to catch the fuel on fire but again isn't fool proof and if there is no collision the plane will be dead in the air.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-02-19T09:34:37.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1811" PostTypeId="2" ParentId="1802" CreationDate="2014-02-19T12:18:06.443" Score="2" Body="&lt;p&gt;Even for military applications, having fully automated aircraft isn't the best of options (except when it comes to cost, pilots cost more than computers).&lt;br/&gt;&#xA;Quite apart from the risk of accidentally losing control over the drone (a solar flare at just the wrong moment, oops), there's the risk of the control link being jammed or even the control systems being hacked and taken over by an opponent.&lt;br/&gt;&#xA;While that's not that great a risk sending a Predator drone over Afghanistan of Somalia, sending the equivalent of a B-2 piloted by computers on a strike to say China does invoke that risk.&lt;br/&gt;&#xA;And I'm not talking about Terminator style robots taking over the world and hunting humans to extinction (which is a big reason why the public has trouble with armed drones) but human interference causing the drone to either crash, divert to an enemy base and be captured, or be reprogrammed to strike back at its owner by the enemy.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And in part that plays in commercial aircraft as well. A well equipped criminal gang could break into the control systems and take them over, sending an airliner with several hundred passengers out of control (or into a holding pattern, demanding ransom). No more trying to sneak people with funny accents onto airliners with plastic explosives in their shoes or underwear, which (romantic though it may be to some, and providing martyrdom to the 'volunteer') isn't very likely to succeed.&lt;br/&gt;&#xA;And that was already a real worry when Boeing and Airbus introduced their Electronic Flight Bag equipment, the idea that someone could break in in an airliner's systems and reprogram those to provide false data to the pilots who'd then use that to fly to the wrong place caused serious headaches (and those things can be reprogrammed only on the ground using a cable from a laptop...).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-02-19T12:18:06.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1812" PostTypeId="2" ParentId="1809" CreationDate="2014-02-19T12:34:30.333" Score="15" Body="&lt;p&gt;&quot;We know that most of the plane accidents and deaths result from the explosion of fuel tanks in the planes&quot;&lt;br/&gt;&#xA;This is a fallacy. Most deaths don't happen because of explosions, but because of impact damage, fire, and inhalation of toxic fumes (in no particular order).&lt;br/&gt;&#xA;Next to that, many people tend to get killed because they are crushed by fellow passengers during evacuations. And some die on the ground being run over by emergency vehicles or from environmental conditions (heat, cold, wildlife).&lt;br/&gt;&#xA;Ratchet Freak correctly points out why your &quot;solutions&quot; won't work (in fact one of them will make the problems worse). And yes, research is being done and has been done. Modern jet fuel has a much higher flame point and vapour pressure than does regular gasoline as a result. Fuel tanks are fitted with baffles and sometimes coolers to keep the fuel liquid so it doesn't explode easily. This is in part a result of what happened to TWA800, one of the very few accidents to be caused by a fuel tank explosion (and there the explosion was itself only possible due to a combination of rare circumstances and chance events, made worse by maintenance problems with the aircraft).&lt;br/&gt;&#xA;The image of aircraft (and cars, trains, ships, buildings, anything really) blowing up in a wall of flame at the least trouble is one created and perpetuated by Hollywood and has no reflection in reality whatsoever.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-02-19T12:34:30.333" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1813" PostTypeId="2" ParentId="1798" CreationDate="2014-02-19T12:44:04.620" Score="1" Body="&lt;p&gt;Define &quot;with similar angles&quot;. In itself the phrase means nothing.&lt;br/&gt;&#xA;The basic shape of the airframe is of course a function primarilly of its required function to provide lift and enough inner volume for the aircraft's components.&lt;br/&gt;&#xA;Stealth depends on several factors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;absorption&lt;/li&gt;&#xA;&lt;li&gt;scatter&lt;/li&gt;&#xA;&lt;li&gt;deflection&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are functions of the shape and materials used. Creating surfaces that cause incoming EM waves to scatter in many directions rather than being reflected directly back causes the return signal received by a RADAR system to be much weaker, reducing the detection range.&lt;br/&gt;&#xA;But a big part is also played by placing grids in air intakes, shielding sharp edges with sawtooth overlays (see the canopy and bay doors, for example), and covering different parts of the aircraft in different materials.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-02-19T12:44:04.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1814" PostTypeId="1" AcceptedAnswerId="1820" CreationDate="2014-02-19T15:41:22.123" Score="34" ViewCount="87288" Body="&lt;p&gt;Are turboprops really more efficient than jets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, does that mean that airlines who use jets sacrifice fuel for faster flights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GAd6u.jpg&quot; alt=&quot;ATR-72&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="65" LastEditDate="2015-03-17T20:01:33.853" LastActivityDate="2019-03-16T21:59:24.663" Title="Which engine is more efficient between turboprop vs jet?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;&lt;cost&gt;&lt;jet&gt;&lt;turboprop&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1815" PostTypeId="2" ParentId="1803" CreationDate="2014-02-19T15:54:04.947" Score="1" Body="&lt;p&gt;Your first question &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are more experimental class aircraft in the USA than any other. That being said, what type of requirements does an experimental aircraft have to meet. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;is very broad and should probably be its own question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to your second question &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, are there ways around certain regulations? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The short answer is &quot;Yes&quot;.  You can apply to the FAA for a waiver of specific regulations.  It's commonly done for aerobatic contests to permit aerobatics below 1500', within 4 nm of an airway, etc.  The waiver is of extremely limited duration and calls out the regulations to be waived.  Air shows also have them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't personally requested such a waiver but I've seen them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA probably permitted the overflight because the pilot was able to show it was safe, would do no harm, and wouldn't cause them any problems.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-02-19T15:54:04.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1816" PostTypeId="2" ParentId="1802" CreationDate="2014-02-19T16:00:17.073" Score="14" Body="&lt;p&gt;In addition to Lnafziger's excellent post which focuses on the advantages of a human in the cockpit, I will focus on the relation between &lt;em&gt;recent developments&lt;/em&gt; and the fact that there are &lt;em&gt;still&lt;/em&gt; pilots in the cockpit. In commercial aviation, technological changes take a very long time before they are widely adopted. Especially if they require complex changes to the whole industry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose some manufacturer would start to develop a unpiloted transport aircraft today. Just the design of the aircraft and the systems would probably take about 10 years. In parallel certification standards need to be developed. It will probably take another 5 years to certify the aircraft. That would mean that in an optimistic scenario it would take 15 years before the first commercial flight could be made with such an aircraft. During this time conventional piloted aircraft will still be produced. And they will still be produced for a while after unpiloted aircraft becomes available. Now consider that an airframe will be flown for about 30 years, perhaps a little less if it really uneconomical to do so. That means that we will see piloted aircraft for at least another 50 years if we'd start to move to unpiloted commercial aviation today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This also means that for a long time there will be a mix of piloted aircraft and unpiloted aircraft together. How will ATC deal with that? For ATC to deal with unpiloted aircraft, a lot of changes need to be made to ATC systems worldwide. These will take even longer than the development of the aircraft itself. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-02-19T16:00:17.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1817" PostTypeId="2" ParentId="1814" CreationDate="2014-02-19T16:20:01.863" Score="31" Body="&lt;p&gt;For short distances, turboprops are more fuel efficient than jets. On the longer flights, the jet (turbofan) engines win the race. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbofan engines perform best at high altitudes. At medium and low altitudes, the turboprops are more efficient engines. Since all flights start and end at low altitudes, the high altitude cruise segment needs to be long enough for the turbofan engine to offset it's disadvantage during start and landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The break even point is somewhere between 300 and 500 NM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The jets are indeed faster, but on short flights the time difference is marginal. A large percentage of the time is spent on the airport and at low altitude where speed is often restricted. The longer the flight is distance wise, the time factor becomes an import advantage for the jet. Not only do passenger like the shorter flight, but it also means less cost for the operator that pays pilots and flight attendants by the hour.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-19T17:04:03.100" LastActivityDate="2014-02-19T17:04:03.100" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1819" PostTypeId="2" ParentId="1802" CreationDate="2014-02-19T16:30:46.220" Score="41" Body="&lt;p&gt;To play devil's advocate, there were two illustrative examples in 2009:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;US Airways Flight 1549&lt;/strong&gt; was safely landed on the Hudson, a feat that the autopilot could not have handled; but&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Air France Flight 447&lt;/strong&gt;'s autopilot handed control back to the pilots, and their incorrect reactions contributed to the loss of everyone on board.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The idea of the pilot &quot;up front who can take over and carry them to safety&quot; is comforting, but not necessarily accurate. It's worth noting that Chesley &quot;Sully&quot; Sullenberger, the pilot from Flight 1549, was a former USAF pilot, arguably better trained to deal with the situation than the average commercial pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although it is accurate to say that a pilot can respond to situations an autopilot isn't programmed for, it is not accurate to say that an autopilot &lt;em&gt;couldn't be&lt;/em&gt; programmed to deal with extreme situations. I can't lay my hands on it now, but I remember seeing a video where an autonomous pilot system corrected for the explosive removal of a model plane's wing, testing the control inputs and corresponding outputs to adapt to the loss (NASA's &lt;a href=&quot;http://ti.arc.nasa.gov/tech/asr/aces/&quot;&gt;Adaptive Control&lt;/a&gt; seems similar).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect we will ease into full automation of aviation, via the equivalent of today's drone pilots; imagine a group of pilots, ready to remotely take over in circumstances beyond those autopilots can handle, at some ground location, able to patch in to the airliner remotely. Freight will likely be an earlier adopter on cost grounds, with passenger following once a sufficient safety level is demonstrated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equally, automation outside the cockpit has further to go; some of Lnafziger's scenarios would not occur if the ATC was also autonomous, for example. As in other forms of transportation, there may be issues with autonomous and conventional vehicles operating alongside one another that would have to be ironed out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I agree that the social aspects are far more pressing here than the technological ones, though; people's acceptance of autonomous technologies seems set to lag their performance.&lt;/p&gt;&#xA;" OwnerUserId="907" LastEditorUserId="907" LastEditDate="2015-05-17T19:36:26.583" LastActivityDate="2015-05-17T19:36:26.583" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="1820" PostTypeId="2" ParentId="1814" CreationDate="2014-02-19T16:57:38.133" Score="39" Body="&lt;p&gt;The short answer to both your questions are &lt;strong&gt;Yes&lt;/strong&gt;. The long answer is, it's not so simple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/ATR-72&quot;&gt;ATR 72&lt;/a&gt; you have pictured has a top speed of 276 knots and a range of 1,300 miles. It can carry around 70 passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://casa.gov.au/manuals/regulate/acm/256r003.pdf&quot;&gt;This document&lt;/a&gt; provides detailed comparisons of burn rates. So we can see the ATR 72 burns about 810 Liters per hour (about 214 gallons/hr). A &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737&quot;&gt;Boeing 737-400&lt;/a&gt; seats about 150, has a maximum range of about 2,400 miles, and a cruising speed of about 473 knots (almost double the range, and over 1.5 times the speed). But its burn rate is about 3,000 liters per hour (793 gallons).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is it a strict trade-off? Speed for Efficiency? Well, not entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TAS is &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/True_airspeed&quot;&gt;true airspeed&lt;/a&gt;&lt;/em&gt;. That is, &lt;code&gt;the speed of the aircraft relative to the airmass in which it is flying&lt;/code&gt;. However, an &lt;em&gt;decrease in density&lt;/em&gt; (e.g. high altitudes; air is less dense) will yield an &lt;em&gt;increase in TAS&lt;/em&gt;. Thus, it is easier to fly at the same &lt;em&gt;true airspeed&lt;/em&gt; at higher altitudes. Since jets are generally used on longer flights (where much of the time in the air is spent at high cruise altitude), they have to work less to fly the same speed as they would 10,000 feet below. There are other reasons why jets are more efficient at high altitudes - they have to combine less fuel with the thinner air, and there is less drag at high altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why don't propeller planes fly at high altitudes then? Well, part of it is that turboprops are &lt;em&gt;less efficient&lt;/em&gt; at higher speeds &lt;strong&gt;and&lt;/strong&gt; higher altitudes, and jets (&lt;a href=&quot;http://en.wikipedia.org/wiki/Turbofan&quot;&gt;turbofans&lt;/a&gt;) are &lt;em&gt;more efficient&lt;/em&gt; at both (obviously to a point, but airliners don't fly fast or high enough to decrease their efficiency again).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since jet engines can also produce more thrust, they are better suited to large airplanes, which are the ones used for &lt;em&gt;long distances&lt;/em&gt; (e.g. if you wanted a propeller plane the size of an Airbus A380, you would need a lot more than 4 engines). So jets are used in situations where they are more economical, and props where they are more economical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turboprop characteristics&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Efficient at low speed, low altitude&lt;/li&gt;&#xA;&lt;li&gt;Low thrust&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This leads to smaller aircraft on shorter, slower routes, like you've observed, since they don't &lt;em&gt;have to&lt;/em&gt; climb or fly fast to get there in a reasonable amount of time. Also these short hops generally require &lt;em&gt;fewer passengers&lt;/em&gt;, or flying a second flight is better than needing a much bigger plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbofan characteristics&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Efficient at high speed, high altitude&lt;/li&gt;&#xA;&lt;li&gt;High thrust&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This leads to larger aircraft on longer, faster routes, like you've observed, since they &lt;em&gt;need&lt;/em&gt; to fly higher and faster to get there in a reasonable amount of time. Also since these routes are more &quot;popular&quot;, and it costs so much to fly that far, it makes more sense to put more passengers on one plane, than two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, an airline would &lt;em&gt;not&lt;/em&gt; sacrifice fuel for faster flights &lt;em&gt;if that was the only advantage&lt;/em&gt;, unless they knew there could be a price premium for the faster flight (e.g. Concorde).&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-02-19T17:23:22.957" LastActivityDate="2014-02-19T17:23:22.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1821" PostTypeId="2" ParentId="1807" CreationDate="2014-02-19T20:20:17.807" Score="36" Body="&lt;p&gt;Flight hours are limited to 30 hours in 7 days, 100 hours in a month and 1000 in a year.  Scheduling rules also say I need at least 1 day off a week, so 6 day trips are the max for me (121 US domestic scheduled).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at a typical trip, which at my company tended to be a 4 day trip.  You want good productive trips, but you can't always get them.  On a 4 day trip let's say I have 6 hours of flight scheduled each day, or 24 hours scheduled that week.  I am getting paid the better of 24 hours or the actual flight time.  Now let's look at my duty day.  For a 6 hour day with 4 legs it was not unheard of to have a 12 hour duty day.  So now for a 4 day trip, I'm &quot;at work&quot; 48 hours and being paid for half of that.  Now consider that I'm not going home every night and my trip starts at 6 am on Friday and ends at midnight Monday night -- that totals to 90 hours away from home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does this compare to a 40 hour work week in an office?  In that case you are on duty 40 hours, getting paid 40 hours (or salary) and if you have a 1 hour commute one way, you are spending 50 hours away from home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to the flight schedule.  A given month will have trips less productive than 24 hours and although you can probably build a 96 hour month if you tried, the average line of flying is typically going to be 75 hours of flying.  You can ballpark that will equate to 150 duty hours and 300 hours away from home for the month.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extrapolate that to a year, and you have 900 flight hours, 1800 duty hours and 3600 hours away from home.  I would say this represents the average US domestic 121 pilot.  Some do more, some do less, but this is pretty typical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do we do with all of that duty time that isn't flying?  Let's see:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Eating&lt;/li&gt;&#xA;&lt;li&gt;Updating charts&lt;/li&gt;&#xA;&lt;li&gt;Checking the weather&lt;/li&gt;&#xA;&lt;li&gt;Checking the paperwork&lt;/li&gt;&#xA;&lt;li&gt;Coordinating with gate agents, ramp agents, fuel agents to make sure we leave on time&lt;/li&gt;&#xA;&lt;li&gt;Programming the FMS and getting our IFR clearance&lt;/li&gt;&#xA;&lt;li&gt;Preflighting the airplane&lt;/li&gt;&#xA;&lt;li&gt;Postflighting the airplane&lt;/li&gt;&#xA;&lt;li&gt;Doing the weight and balance&lt;/li&gt;&#xA;&lt;li&gt;Sleeping&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note, that all of these activities require we are at the airport, in the secure area and we are not being paid.  The pay clock starts (roughly) when the airplane is buttoned up and the parking brake is released and ends when the parking brake is set and main cabin door opened.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="8282" LastEditDate="2017-07-29T11:28:01.573" LastActivityDate="2017-07-29T11:28:01.573" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="1822" PostTypeId="2" ParentId="1245" CreationDate="2014-02-19T20:23:07.017" Score="7" Body="&lt;p&gt;Well, since you are asking about 'statistically' :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a Boeing presentation entitled &lt;strong&gt;&lt;a href=&quot;https://www.google.ro/search?q=V1+and+the+Go+/+No+Go+Decision&quot; rel=&quot;nofollow&quot;&gt;'V1 and the Go / No Go Decision'&lt;/a&gt;&lt;/strong&gt; from 2002&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In there it presents the case of Rejected TakeOffs and Overruns out of an estimated &lt;strong&gt;76,000 RTOs&lt;/strong&gt; studied between 1958 and 1990 about &lt;strong&gt;74 ended in Overruns&lt;/strong&gt;. 56% of them were initiated after V1 (most of them &gt;120kts), and also 56% of them were avoidable completely by continuing the takeoff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This puts your statistical chances of a mishap about 0.1% in case of RTO before V1 and about 56% after. If you think you have a better chance in the air, take the flight.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="72" LastEditDate="2014-04-23T12:41:06.800" LastActivityDate="2014-04-23T12:41:06.800" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1823" PostTypeId="2" ParentId="1798" CreationDate="2014-02-19T23:07:49.560" Score="9" Body="&lt;p&gt;I assume you're using the term 'similar angles' in a geometric sense, to mean that the angle from a reference like the aircraft centerline to the lines made by two structural features are the same.  Your photo shows this well, with the wing leading edge angle the same as the horizontal stabilizer leading edge angle and the same as the inlet (?) angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the reason for this is that the overall likelihood of radar detection is lower because each of these features will reflect radar signal in the same direction as one another.  This means that the reflection will be very much stronger in the direction they reflect, but that reflection has a very narrow spread.  In contrast, the features will not reflect radar strongly at all other angles.  Thus the radar dish has to be &quot;lucky&quot; to be at exactly the right angle from the aircraft to receive the strong signature, and so the overall probability of detection is reduced since at most angles the reflection signature is reduced.  This is also the reason that flat surfaces are used in many stealth designs.&lt;/p&gt;&#xA;" OwnerUserId="643" LastActivityDate="2014-02-19T23:07:49.560" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1824" PostTypeId="2" ParentId="1801" CreationDate="2014-02-19T23:12:33.640" Score="5" Body="&lt;p&gt;Unfortunately you seem to be conflating a two distinct issues in one question.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Computer control of aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Unstable aircraft design.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;First dealing with computer control, or flight control systems. Many modern designs military and civil are using digital fly by wire (FBW) systems. This has little or nothing to do with aircraft stability. These systems often have no mechanical backup, so in reality the pilot is merely instructing the computer how to fly the plane. Modern FBW systems use a quadraplex system, i.e. there are 4 duplicate computers. 3 are active and one is hibernating. Then if one system goes duff the other 2 can switch the duff one off and bring the 4th out of hibernation. If you only had 2 computers how do you know which one is wrong? - hence 3 are used. Prior to flight clearance these systems are tested with thousands of hours of rig testing, safety checks etc. Whole volumes have been written on the subject.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second issue - unstable aircraft design. Again a couple of comments, first aircraft instability levels are not driven by manoeuvrability requirements - modern military aircraft are aerodynamically unstable for supersonic performance not manoeuvrability. Modern FBW systems allow designers to explore unstable designs but there is a limit. Originally the FBW systems were looking at pitch instability but now it is being extended to lateral instability for some of the more novel stealth designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in terms of your two proposed conditions - if there is a mechanical backup then pilots can adapt and are capable of controlling slightly unstable configurations in the event of a failure, although they may whinge a little about the handling qualities. For a fully digital FBW system then for your proposed conditions then as the systems failed there would be a gradual degradation in flying qualities but there would still be a backup system allowing a return to base capability. To have a total loss in control then there would have to occurred a series of multiple failures. Again risk and safety assessments are another whole volume of work.&lt;/p&gt;&#xA;" OwnerUserId="769" LastEditorUserId="769" LastEditDate="2014-02-20T08:13:41.097" LastActivityDate="2014-02-20T08:13:41.097" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1825" PostTypeId="1" CreationDate="2014-02-20T01:42:33.973" Score="6" ViewCount="2145" Body="&lt;p&gt;After September 11th, the FAA required all Part 135 air carrier flights to prefix their registration number with a &quot;T&quot; and use the &quot;Tango November&quot; prefix on the radio.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every once in a great while (about once to twice a year) I still hear someone doing this, but surely there are more 135 flights than this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it (or was it ever) &lt;strong&gt;required&lt;/strong&gt; to use the &quot;T&quot; prefix for Part 135 flights?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-20T08:57:14.220" LastActivityDate="2014-12-08T17:18:10.603" Title="Is a &quot;T&quot; (Tango) prefix required before the registration number for Part 135 flights?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;flight-planning&gt;&lt;far-135&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1826" PostTypeId="2" ParentId="1825" CreationDate="2014-02-20T03:51:06.613" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html#byIa0JACK&quot; rel=&quot;nofollow&quot;&gt;AIM 4-2-4&lt;/a&gt;, part A.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;4. Air Taxi or other commercial operators not having FAA authorized call signs should prefix their normal identification with the phonetic&#xA;  word &quot;Tango.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE- Tango Aztec Two Four Six Four Alpha.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It was pre-911 but not often used. It is just a way for operators who have no callsign to let ATC know that they are a charter operation. If appropriate, it may be dropped after initial contact, just like shortening your tail number.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="69" LastEditDate="2014-02-20T05:22:00.617" LastActivityDate="2014-02-20T05:22:00.617" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1827" PostTypeId="1" CreationDate="2014-02-20T06:04:27.197" Score="8" ViewCount="1393" Body="&lt;p&gt;I worked on Russian Fighter aircraft where both the Rudder Pedals were mechanically interlinked i.e Captain applies force on his pedal than both pedals (Captain &amp;amp; First Officer) move &amp;amp; vice versa. Single Pedal sensor Unit (of course redundant sensors) senses the position and sends it to the Fly-By-Wire Computer for moving the control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to know if this is true for all aircraft (Fighter/Commercial, Boeing/Airbus, etc.) and if not, what are different implementations? Maybe different sensors for Captain/First Officer, different arch etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also on the same lines, how does Pedal Feel operate i.e, does it takes a signal from pilot pedal sensor or from actuators to provide feel to the pilot/copilot?&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="19" LastEditDate="2017-05-05T08:58:58.437" LastActivityDate="2017-05-07T16:02:00.243" Title="Do the captain's and first officer's rudder pedals always move together?" Tags="&lt;flight-controls&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1828" PostTypeId="1" AcceptedAnswerId="1845" CreationDate="2014-02-20T07:29:59.043" Score="13" ViewCount="7470" Body="&lt;p&gt;If it were a beautiful sunny VFR day and you were cleared for a circling approach, can you begin the circle prior to the final approach fix/circling DH in order to maneuver visually to land?&lt;/p&gt;&#xA;&lt;p&gt;Here are two examples of situations where it would be very useful, and both are real life clearances that I have gotten multiple times:&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Example 1 - KASE&lt;/h1&gt;&#xA;&lt;p&gt;Clearance:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;N1234, Cleared for the VOR/DME-C approach, cleared to land runway 15&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UgSIl.png&quot; alt=&quot;KASE VOR/DME-C&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;If you follow the step downs until the final approach fix (ZIGBU) you will be at 2,983 ft. above the runway (10,820 ft. MSL) with 2.9 miles to go (9.61 degree descent angle).  To put this in perspective, on a normal 3 degree descent, you should be at 870 ft. above the runway so are over 2,000 ft. high on less than a 3 mile final.&lt;/p&gt;&#xA;&lt;p&gt;Could you begin the circle early and descend while visually avoiding any obstacles prior to the step-down fixes?  Say cross ALLIX at 11,000 ft. and ZIGBU at 9,000 ft. (assuming that this cleared all obstacles)? Keep in mind that this is a circling approach so we will be operating below the MDA visually at some point on final anyway.&lt;/p&gt;&#xA;&lt;p&gt;If not, then it would be nearly impossible to land straight-in while flying most jets, and yet I have never seen anyone do a 360 or a similar maneuver while on final here (and who would want to do that in the valley anyway??).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Example 2 - KTEB&lt;/h1&gt;&#xA;&lt;p&gt;Clearance:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;N1234, Cleared for the ILS Runway 6 Circle Runway 1 Approach, cleared to land runway 1&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z1H9r.png&quot; alt=&quot;KTEB ILS 6&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;If I fly the ILS (localizer and glideslope) until reaching circling minimums, especially in a category C or D airplane and with this runway layout, it will take a lot of room to turn right for a base leg to runway 1 and then turn back left to intercept final and lose the required altitude.&lt;/p&gt;&#xA;&lt;p&gt;Could you start the circle a little sooner by making the right turn early (prior to DH, but still within the protected circling area) in order to intercept the extended final for runway 1?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-21T06:47:29.460" Title="When flying a circling approach, is it permitted to begin the visual circling segment prior to the final approach fix?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;&lt;non-precision-approach&gt;&lt;instrument-procedures&gt;&lt;terps&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1829" PostTypeId="2" ParentId="1827" CreationDate="2014-02-20T07:58:29.240" Score="3" Body="&lt;p&gt;All? I doubt there's anyone who knows all models of aircraft but it seems the norm at least. &lt;br/&gt;&#xA;How they operate depends on the aircraft of course. Anywhere from fully mechanical, direct linkage to the rudder through cables to directly driving hydraulic pumps that drive the rudder to driving sensors that feed data to the flight control computers which in turn drive electric motors that drive the hydraulic pumps that drive the rudder.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-02-20T07:58:29.240" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1830" PostTypeId="1" CreationDate="2014-02-20T09:11:11.940" Score="10" ViewCount="990" Body="&lt;p&gt;Quadcopters, by virtue of software-piloting rather than human-piloting, are capable of new modes of flight. I've seen one in which the machine maintains altitude &lt;a href=&quot;http://www.engineering.com/DesignerEdge/DesignerEdgeArticles/ArticleID/6542/Athletic-and-Adapting-Quadcopters.aspx&quot; rel=&quot;nofollow&quot;&gt;despite the loss of two rotors by spinning (yaw)&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder about a different mode, though; if a quadcopter could maintain a very high degree of pitch, then the flight is closer to a very short 4-engine X-wing aeroplane. This would be the advantage of a tiltrotor; after takeoff, rotate into the near-vertical position and permit much higher rates as we are no longer limited by usual helicopter dissymetry of lift arguments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this possible? &lt;em&gt;Are there other modes beyond the capacities of traditional aircraft?&lt;/em&gt; E.g. yaw spinning in the forward pitch position, coast-and-burn by varying the pitch periodically to switch between gaining altitude and gaining forward momentum, etc.&lt;/p&gt;&#xA;" OwnerUserId="748" LastEditorUserId="15311" LastEditDate="2017-12-06T14:38:09.127" LastActivityDate="2017-12-06T14:52:13.900" Title="Does a quadcopter have flight modes beyond traditional aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;aircraft-limitations&gt;&lt;quadcopter&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1831" PostTypeId="2" ParentId="1245" CreationDate="2014-02-20T13:13:05.947" Score="3" Body="&lt;p&gt;In light airplanes, if you have runway remaining, landing is the preferred choice even once you've taken off.  It's not a &quot;ground reject or continue&quot; choice.  It's a 3 stage process.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Can I reject safely on the ground?&lt;/li&gt;&#xA;&lt;li&gt;After that point, Can I now land safely in the remaining distance (or even have a survivable runoff, which you may choose if you &lt;em&gt;know&lt;/em&gt; your particular airplane can't climb on remaining engines)&lt;/li&gt;&#xA;&lt;li&gt;After that, I'm committed to lost engine procedures and attempting to fly (in some configurations, sustained flight is not possible and you're actually committing to an off airport landing)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-02-20T13:13:05.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1832" PostTypeId="2" ParentId="1827" CreationDate="2014-02-20T14:35:33.293" Score="15" Body="&lt;p&gt;In the EMB-145 and -135 the rudder controls are mechanically linked in the tail in an assembly that converts torque from the rudder cables to linear rod input into the rudder hydraulic control units.  Up until this assembly the rudders are technically independent and the cables for each rudder are routed differently through the airframe so that a single point of damage does not render the rudder inop.  The autopilot servo is only located on the captains rudder cables.  Through the rear linkage both pilots rudder pedals will move together when either provides input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our other controls are a bit more interesting.  The roll input is also linked, but it is linked at the control column,  Each yoke independently controls its own aileron -- the CA yoke only flies the left aileron and the FO yoke the right aileron.  It is only through the control column linkage that each yoke can control the whole airplane.  It is done this way so that if there is a problem with a cable jamming, the control interlock can be disconnected and at least half control regained.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-20T14:35:33.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1833" PostTypeId="1" CreationDate="2014-02-20T14:40:41.973" Score="19" ViewCount="1736" Body="&lt;p&gt;Some airlines, Delta in particular, have dark underbellies on their liveries. Is this only aesthetic or is there a purpose for it?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2015-03-23T16:55:21.960" LastActivityDate="2015-06-15T14:07:18.653" Title="Why are airliner underbellies generally painted differently?" Tags="&lt;airliner&gt;&lt;livery&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1834" PostTypeId="2" ParentId="1802" CreationDate="2014-02-20T15:33:51.750" Score="7" Body="&lt;p&gt;Surely the main reason is moral hazard&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot is probably literally going to be the first to die seeing as he's sitting at the front so he's reasonably well motivated to do the job properly&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember a friend of mine who was an army aircraft technician was obliged to go on all test flights after he'd completed a repair for the very same reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the concept of civilian drones will die (and probably some poor people on the ground along with it) following the first crash of such a vehicle.&lt;/p&gt;&#xA;" OwnerUserId="925" LastEditorUserId="925" LastEditDate="2014-02-20T15:43:47.400" LastActivityDate="2014-02-20T15:43:47.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1835" PostTypeId="2" ParentId="1833" CreationDate="2014-02-20T16:38:50.337" Score="7" Body="&lt;p&gt;Aircraft are generally a nice bright white. Aside from the company logo, this leaves the other company colors needing a space. The tail, engine cowlings and underbellies are the more effective places to put it. There is color on the tail, color on the bottom, and the logo in between.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/3/33/Boeing_747-8_first_flight_Everett,_WA.jpg&quot; alt=&quot;747&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, the lower one lifts forward the identity of the company much better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.deltamuseum.org/images/site/history-livery/boeing-777-new-livery.jpg?sfvrsn=2&quot; alt=&quot;delta&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.740" LastActivityDate="2015-06-15T14:07:18.653" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1836" PostTypeId="2" ParentId="1828" CreationDate="2014-02-20T18:45:51.843" Score="1" Body="&lt;p&gt;You cannot legally descend below minimum altitudes. Going to 11,000' before Allix or 9000' before Zigbu is not allowed unless you cancel IFR or are cleared for a visual approach. Sometimes the stepdowns are used to keep you above traffic instead of obstacles. That's the case at Orlando International, for example, where the ILS approach from the north overflies the ILS approach from the east at Orlando Executive.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-02-20T18:45:51.843" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1837" PostTypeId="1" CreationDate="2014-02-20T18:50:35.690" Score="11" ViewCount="8891" Body="&lt;p&gt;Most ILS approaches include localizer minimums that can be used if the glideslope transmitter or receiver fails.  For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TJabp.png&quot; alt=&quot;KFXE ILS 8&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, to fly the ILS you would intercept the glideslope just before PRAIZ and fly the 3 degree glideslope down to minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we were cleared for the ILS approach, but we instead wanted to ignore the glideslope and fly the LOC only approach&lt;sup&gt;1&lt;/sup&gt; (for whatever reason:  training, practice, etc.), could we do that without specific ATC approval since it is on the same chart and says &quot;ILS or LOC&quot;?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; We could fly the LOC only approach by crossing PRAIZ at 2,200 ft. and then descend at an &quot;optimum&quot; rate until leveling off at the MDA of 520 ft.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-23T12:11:57.120" Title="Is it legal to fly the localizer approach when cleared for the ILS?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;iaps&gt;&lt;instrument-procedures&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1838" PostTypeId="2" ParentId="1828" CreationDate="2014-02-20T21:38:25.023" Score="2" Body="&lt;p&gt;Well, some of the things you are talking about are not even permitted for a visual approach :-)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's my 2c :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO Doc 8161 7.2.2&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After initial visual contact, the basic assumption is that the runway&#xA;  environment should be kept in sight while at minimum descent&#xA;  altitude/height (MDA/H) for circling&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The circling approach allows you to fly at/below the MDA around the airport while having (part of) the airport in sight AND while inside the circling approach area (~4.5 miles max for category E). It's not a license to disregard altitude restrictions while descending on the approach. It's also not a license to start flying around the class D airspace at will.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For KASE the highest category allowed for circling is C. The protected area (centered around the runway threshold) for category C is 1.7NM.  You cannot begin your circling until 1.2 NM after ZIGBU. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that after ZIGBU you can descend to the circling MDA of 10220 and with the airport in sight you can continue to descend all the way to the rwy threshold any time you wish. How are you going to lose 3000' in 2.9 NM I have no idea. But I'm pretty sure a circle to land clearance does not allow you to break that &quot;10820' or above&quot; restriction.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-02-20T23:14:17.470" LastActivityDate="2014-02-20T23:14:17.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1839" PostTypeId="1" CreationDate="2014-02-20T22:08:44.910" Score="12" ViewCount="4059" Body="&lt;p&gt;I am wondering which companies develop software for systems on airplanes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a software engineer major and I would love to work with planes in some way. I am not sure if that would be more of an electrical engineering position or not, any input would be greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="928" LastEditorUserId="97" LastEditDate="2014-04-07T22:57:25.930" LastActivityDate="2019-02-08T14:36:27.587" Title="Which companies develop software for airplane systems?" Tags="&lt;career&gt;&lt;software&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ClosedDate="2019-02-10T05:10:31.380" ContentLicense="CC BY-SA 3.0" />
  <row Id="1840" PostTypeId="1" AcceptedAnswerId="1841" CreationDate="2014-02-20T22:44:52.280" Score="18" ViewCount="5956" Body="&lt;p&gt;I frequently hear the tower instruction &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Report a two mile base for runway 5&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is the intention of that instruction? I realize that under these circumstances that we're not looking for pinpoint precision, but still it would be nice to know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the record, I'm not asking what a base is (or the fact that &quot;left&quot; is implicit), but what two miles are we talking about? Two miles straight line distance from the threshold? A base to a two mile final? On the base leg, two miles from the centerline? (I'm pretty sure the last one isn't it, but hey, I've been wrong before)&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2019-07-19T18:23:37.733" Title="What is a two- or three-mile base exactly?" Tags="&lt;air-traffic-control&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1841" PostTypeId="2" ParentId="1840" CreationDate="2014-02-20T22:53:11.170" Score="10" Body="&lt;p&gt;They basically ask you to report it as a &quot;memory jogger&quot; for themselves so that they can do something when you call in (like clear you to land).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A standard airport traffic pattern is described in Chapter 7 of the Airplane Flying Handbook as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The downwind leg is a course flown parallel to the landing runway, but&#xA;  in a direction opposite to the intended landing direction. This leg&#xA;  should be approximately 1/2 to 1 mile out from the landing runway, and&#xA;  at the specified traffic pattern altitude. During this leg, the before&#xA;  landing check should be completed and the landing gear extended if&#xA;  retractable. Pattern altitude should be maintained until abeam the&#xA;  approach end of the landing runway. At this point, power should be&#xA;  reduced and a descent begun. The downwind leg continues past a point&#xA;  abeam the approach end of the runway to a point approximately 45° from&#xA;  the approach end of the runway, and a medium bank turn is made onto&#xA;  the base leg.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.vatusa.net/training/Traffic_Pattern.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BZJQb.gif&quot; alt=&quot;AIM Traffic Pattern&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the tower asks you to fly a two mile pattern, they want you to fly a pattern that has the downwind leg 2 miles out from the runway instead of the 1/2 to 1 mile that is normal.  The base leg would still be turned when 45° from the approach end of the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, you are either:  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Doing pattern work in which case you fly the two mile wide pattern and should report turning base, or&lt;/li&gt;&#xA;&lt;li&gt;Approaching the airport and the controller would like you to enter the two mile wide pattern on the base leg.  You should report the point where you would have normally turned onto the base leg if you were flying the entire pattern (45° to the runway).  This would actually be both of your last two scenarios above:  Established on the base leg, two miles prior to intercepting a two mile final (which for fun would actually be 2.83 miles from the runway).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-21T06:05:29.127" LastActivityDate="2014-02-21T06:05:29.127" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1842" PostTypeId="2" ParentId="1839" CreationDate="2014-02-20T23:31:51.303" Score="11" Body="&lt;p&gt;This entire branch is known as  avionics (aviation electronics). Limited work is generally done by the aircraft producers themselves, and the majority is subcontracted to specialist companies. A name which does come to mind is &lt;strong&gt;Thales group&lt;/strong&gt;, who are behind much of the Airbus A380 avionics. Other ones are &lt;strong&gt;Rockwell Collins&lt;/strong&gt;, &lt;strong&gt;Honeywell&lt;/strong&gt; and &lt;strong&gt;Garmin&lt;/strong&gt;. These are however though often at the top of an iceberg of various subsystems and controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.fujaa.ae/gallery/158.jpg&quot; alt=&quot;g1000&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A huge increase in this field (particularly in small aircraft but now also coming to larger ones) has been in tablet computers and the like in the past few years, and while I'm not a pilot I think it's hardly at the limit of what is possible. An iPad has more processing power than most if not virtually all aircraft flying today. Many customers today are disappointed if they don't get WiFi and inflight entertainment onboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the increase in drones and unmanned aircraft, it's certainly not a shrinking field. A large area of this includes complex calculations and plenty of sensors. And more drones and unmanned aircraft require advanced communication and control systems. I've even heard about dynamic models of aircraft who adapt the plane's control to maintain control in the event of structural failure or serious damage. Only having scratched the field personally it's a very broad field with plenty.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.753" LastActivityDate="2014-02-20T23:49:17.277" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1843" PostTypeId="2" ParentId="1837" CreationDate="2014-02-21T03:30:44.773" Score="1" Body="&lt;p&gt;That's even very common when doing flight training, but instead of going to Exec I would sugest yo to shoot a real LOC (only) approach in Pompano just north of it ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't offer you the 100% legal, floorless, perfect answer for this but ther has been no trouble, yet. Probably the most correct option you have is to particularly ask for the LOC APCH for flight training, but if you demonstrate good airmen ship flying the approch, following a predetermined descend profile leveling off half a mile prior to your DTL, this sould even keep you within half scale until leveling off at yor MDA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't matter on which plate the approach is printed, the key point for ATC is, that you are following the same lateral and approximately the same vertical profile, at pretty much the same speed. Ther is obviously no other technique to maintain seperation required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you should not plan on doing this without one crew member having the runway inside, or at least with a cloud base reported well above your LOC minimums. If you fail your glide path indicator (put a sticker on it) and you are - for any reason - not visual with the runway at your minimums passing the DTL go around, do not change back to the ILS.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-03-01T19:29:09.670" LastActivityDate="2014-03-01T19:29:09.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1844" PostTypeId="1" AcceptedAnswerId="1930" CreationDate="2014-02-21T04:23:39.850" Score="6" ViewCount="1713" Body="&lt;p&gt;I recently saw an argument in a forum I frequent that sumping the tanks when the system was below freezing was a &lt;em&gt;bad idea&lt;/em&gt;, as you can't drain solid ice from the fuel system, and there is a chance that ice may jam the drain open, causing your entire tank of avgas to empty onto the ramp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this is certainly a possibility, is it a reason to skip sumping the fuel system during preflight, or do the reasons for checking the fuel system outweigh the risk of a tank of fuel winding up on the ground?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-25T21:36:21.153" Title="Should you sump fuel tanks when the fuel system is below freezing?" Tags="&lt;piston-engine&gt;&lt;preflight&gt;&lt;cold-weather&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1845" PostTypeId="2" ParentId="1828" CreationDate="2014-02-21T04:57:00.437" Score="10" Body="&lt;p&gt;While researching this subject, I found a few things that shed light on the subject:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Procedures&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0408.html&quot; rel=&quot;noreferrer&quot;&gt;FAA ATC Order 4-8-1&lt;/a&gt; Note 1 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; Clearances authorizing instrument approaches are issued on the basis that, if visual contact with the ground is made before the&#xA;  approach is completed, the entire approach procedure will be followed&#xA;  unless the pilot receives approval for a contact approach, is cleared&#xA;  for a visual approach, or cancels their IFR flight plan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So we have to follow the entire approach, which includes all mandatory altitudes.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aspen Approach&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0310.html#atc0310.html.6&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;AIM 5-4-20. Approach and Landing Minimums&lt;/strong&gt;&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. Straight-in Minimums are shown on the IAP when the final approach&#xA;  course is within 30 degrees of the runway alignment (15 degrees for&#xA;  GPS IAPs) and a normal descent can be made from the IFR altitude shown&#xA;  on the IAP to the runway surface. When either the normal rate of&#xA;  descent or the runway alignment factor of 30 degrees (15 degrees for&#xA;  GPS IAPs) is exceeded, a straight-in minimum is not published and a&#xA;  circling minimum applies. The fact that a straight-in minimum is not&#xA;  published does not preclude pilots from landing straight-in if they&#xA;  have the active runway in sight and have sufficient time to make a&#xA;  normal approach for landing. Under such conditions and when ATC has&#xA;  cleared them for landing on that runway, pilots are not expected to&#xA;  circle even though only circling minimums are published. If they&#xA;  desire to circle, they should advise ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The key part for this discussion is that, for approaches that would be straight-in if it weren't for the high descent rate on final (like the KASE approach), &lt;strong&gt;pilots are not expected to circle even though only circling minimums are published. If they desire to circle, they should advise ATC.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, in this case we can't land straight-in after making the last crossing restriction, so what can we do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combining the two quoted passages, our options are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Get approval for a contact approach&lt;/li&gt;&#xA;&lt;li&gt;Get approval for a visual approach&lt;/li&gt;&#xA;&lt;li&gt;Cancel our IFR flight plan&lt;/li&gt;&#xA;&lt;li&gt;Get approval to circle since we can't land straight-in.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The first three are pretty straight-forward and can be used if you pick up the airport visually in time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to circle, I found a great article called &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1430.PDF&quot; rel=&quot;noreferrer&quot;&gt;Circle-To-Land Tactics&lt;/a&gt; which was written by a former chairman of the ALPA TERPs committee.  He suggests overflying the runway and then flying a modified pattern:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lG6jV.png&quot; alt=&quot;circle pattern&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Teterboro Approach&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;We can't start our circle until we are within the protected circling area.  This means that for my category C airplane, I have to wait until 1.7 NM from the runway threshold before I can begin my turn.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We could make a right 90 degree turn followed by a left 90 degree turn to line up on final, but that would eat up about one mile just by turning.  Since runway 1 is actually closer to us than 6 at this point, I have even less distance to work with and can't even see the runway during the first turn because we are banking the wrong direction.  This would be pretty tight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the previous article recommends a circle like this (which would be modified for our actual runway layout):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gNFUY.png&quot; alt=&quot;KTEB Circle&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In good visual conditions, I would just ask for a visual approach so that we can start the turn a little sooner and land &quot;more&quot; straight-in without flying all over the airport.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One last point:  Since there is a control tower at both of these airport, make sure that they know what we are going to do!  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-21T06:47:29.460" LastActivityDate="2014-02-21T06:47:29.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1846" PostTypeId="1" CreationDate="2014-02-21T05:13:36.543" Score="6" ViewCount="1726" Body="&lt;p&gt;I was told a long time ago that having the weather radar turned on when at low altitudes helps to scare birds out of your way because the can sense/feel the radar.  Casey also mentioned this in &lt;a href=&quot;https://aviation.stackexchange.com/a/1758/69&quot;&gt;another answer of his&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any evidence that weather radar actually scares off birds, or is this another &quot;urban aviation legend&quot;?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="22550" LastEditDate="2018-12-23T03:45:59.550" LastActivityDate="2018-12-23T03:45:59.550" Title="Does weather radar scare off birds?" Tags="&lt;radar&gt;&lt;birds&gt;&lt;weather-radar&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1847" PostTypeId="2" ParentId="1846" CreationDate="2014-02-21T06:35:56.813" Score="5" Body="&lt;p&gt;My guess is it is an urban legend. Ground based weather radar have been used track and &lt;a href=&quot;http://members.ziggo.nl/jaaplangenbach/Dokter-Nachtvluchten%202013.pdf&quot; rel=&quot;noreferrer&quot;&gt;analyse behaviour of birds&lt;/a&gt;. Part of this research was done with the radar in fixed beam mode to record individual wing beat frequencies for species identification, keeping the bird in the radar beam. If the birds would be scared away by the beam this research would be almost impossible (and invalid as well). Of course, that's no hard evidence that the birds aren't scared. Also the distance between the bird and radar plays a role of course. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radar used for that research was operating in the C-band, which is also the frequency band that most aircraft weather radars operate in. Newer aircraft weather radars operate in the X-band, which is a higher frequency band. My gut feeling is that the higher frequency is even less likely to bother birds, but then again, I am not a bird so what do I know? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;jwenting suggested in a comment that this myth might have been started because of incidents where animals and humans have been harmed and killed by high power radar transmissions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has published an &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-68B.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory Circular&lt;/a&gt; on recommended practices and precautions for operating weather radar on the ground. While not concerned with birds, it provides an example calculations of the output power and safe distance of a weather radar. It the example, the safe distance is less than 4.5 meter. That is too close for a bird to avoid a mid air collision. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/sXUsg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iTFEZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-21T09:40:27.430" LastActivityDate="2014-02-21T09:40:27.430" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1848" PostTypeId="2" ParentId="1839" CreationDate="2014-02-21T10:34:49.267" Score="6" Body="&lt;p&gt;As Manfred mentioned, there are quite a number of companies that develop systems for aircraft, all with a software component to it. Whether it is something for you depends a lot on your expertise as a software engineer. Are you doing embedded programming then avionics might be a possibility for you. But you have to realize it is kind of a specialized field that is very strict in its procedures for safety reasons. If you enjoy rapid development processes and see quick improvements you are destined to become very frustrated in the avionics world. It is not a job I would recommend to everyone. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, there are plenty of other software jobs related to aviation. Airports, Air Traffic Control, airlines, maintenance organizations all run dedicated software to support their processes. I did quite some programming in the past for Air Traffic Control related simulations. Nothing safety critical, the focus was on validating new ideas, which in my view was much more fun than working on operational (safety critical) systems. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-02-21T10:34:49.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1849" PostTypeId="1" AcceptedAnswerId="1852" CreationDate="2014-02-21T12:10:09.077" Score="16" ViewCount="7533" Body="&lt;p&gt;I once had a traffic controller give me a hard time about how I requested IFR clearance once in the air. I had previously filed an IFR flight plan, and took off from my untowered home airport. On approach control's frequency, I said:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tampa Approach, Cirrus 123AB, 5 miles southeast of Tampa Exec at 1000 feet, IFR to Ft. Lauderdale Exec&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The approach controller responded, annoyed, saying something like &quot;Well do you have an IFR flight plan or are you reporting IFR??&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had always used that phraseology because it seems the least wordy way to get the info across, which can be helpful when the freq is busy. &lt;strong&gt;What is the technically correct way to get an IFR clearance on an existing IFR flight plan?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="934" LastEditorUserId="572" LastEditDate="2015-02-19T10:01:45.493" LastActivityDate="2016-08-03T18:10:41.783" Title="How do you open and get a IFR clearance while in the air?" Tags="&lt;instrument-flight-rules&gt;&lt;phraseology&gt;&lt;clearance&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1850" PostTypeId="1" AcceptedAnswerId="1853" CreationDate="2014-02-21T13:01:03.117" Score="29" ViewCount="6316" Body="&lt;p&gt;It seems to me that takeoff weight is an important piece of data, and if one had weighing scales between the wheels and the aircraft body, one could precisely determine it. However, searching the internet, there seem to be no scales and cargo/fuel/passenger weight is estimated by adding up what is brought on board. Why aren't scales common? And are there any commercial airplanes that have them?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="22726" LastEditDate="2020-04-04T18:29:56.200" LastActivityDate="2020-04-04T18:29:56.200" Title="Do some airplanes have weighing scales on the landing gear?" Tags="&lt;aircraft-design&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1851" PostTypeId="2" ParentId="1850" CreationDate="2014-02-21T13:10:36.967" Score="14" Body="&lt;p&gt;&lt;strong&gt;Simple answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For one thing it will not work because of wind: Once you put wings on a fuselage, you will need to bring that airplane into an enclosed hangar for the scales be accurate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mind you, this is exactly what being is done whenever an airplane is being weighted for mass &amp;amp; balance purposes, about every three years: enclosed hangar and massive scales under the gears. Doing it on a daily basis in an already crowded airport is not an option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Complex answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you really need to know for your a/c is mass, not weight. Also, you'd want to know the mass distribution inside the a/c, not just to calculate the center of gravity (which a scale can also do), but also to make sure that load limits are respected in each section (which a scale will not do). Adding and removing numbers on a load sheet works pretty good for this purpose, as does estimating passenger weights and luggage as an average, although there are talks that those averages need to be increased lately. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you eventually found a way to scale each airplane before takeoff, in a controlled environment, the extra costs will never be justified since you basically improved on something that works.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-02-21T13:20:16.283" LastActivityDate="2014-02-21T13:20:16.283" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1852" PostTypeId="2" ParentId="1849" CreationDate="2014-02-21T13:30:03.963" Score="21" Body="&lt;p&gt;There is one example in the AIM used for transitioning from VFR to IFR, and it how I've always done it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;AIM 5-2-5. Abbreviated IFR Departure Clearance (Cleared &amp;hellip; as Filed) Procedures&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;EXAMPLE-&lt;/strong&gt;&lt;br&gt;&#xA;  &quot;Los Angeles center, Apache Six One Papa, VFR estimating Paso Robles VOR at three two, one thousand five hundred,&#xA;  request IFR to Bakersfield.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Reference: &lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf#page=304&quot; rel=&quot;noreferrer&quot;&gt;5−2−5. Abbreviated IFR Departure Clearance (Cleared &amp;hellip; as Filed) Procedures&lt;/a&gt;&lt;/strong&gt; (13 MB PDF)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that they specifically say &quot;VFR&quot; right before their current location and also use the word &quot;request&quot; to make it clear what they are looking for.  I would change your request to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tampa Approach, Cirrus 123AB, &lt;strong&gt;VFR&lt;/strong&gt; 5 miles southeast of Tampa Exec&#xA;  at 1000 feet, &lt;strong&gt;request&lt;/strong&gt; IFR to Ft. Lauderdale Exec&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="2143" LastEditDate="2016-08-03T18:10:41.783" LastActivityDate="2016-08-03T18:10:41.783" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1853" PostTypeId="2" ParentId="1850" CreationDate="2014-02-21T14:09:43.640" Score="31" Body="&lt;p&gt;Yes, such system exists, for example the &lt;a href=&quot;https://aerospace.honeywell.com/en/products/navigation-and-sensors/weight-and-balance&quot; rel=&quot;noreferrer&quot;&gt;Honeywell WBS&lt;/a&gt;.* It was &lt;a href=&quot;http://www.sawe.org/papers/0626&quot; rel=&quot;noreferrer&quot;&gt;developed during the sixties&lt;/a&gt; and installed as an option on the Boeing 707-300 freight aircraft. Other aircraft that had a similar (optional) system include the L1011 and Boeing 747.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is mostly found on freight aircraft because they have a less predictable load distribution (centre of gravity) than passenger aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason they are not common is that they add cost in the form of installation, weight and maintenance. While quite accurate when in good condition, the reliability of the weighing systems used to be poor, which probably contributed to the fact they never became wide spread. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because crew are commonly operating on several aircraft types these days that have take-off weights of more than 100 metric tonne difference (e.g. A330 and A340, B747-400 and B747-8) there is an increase in take-off weight confusion related incidents. This, combined with the fact that systems are becoming more reliable, makes it likely that these weighing systems will be used more in the future. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;* An &lt;a href=&quot;https://www.flightglobal.com/FlightPDFArchive/1987/1987%20-%200862.PDF&quot; rel=&quot;noreferrer&quot;&gt;advert for it&lt;/a&gt; in a 1987 &lt;em&gt;Flight&lt;/em&gt; issue.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-10-17T03:42:47.910" LastActivityDate="2017-10-17T03:42:47.910" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1854" PostTypeId="1" AcceptedAnswerId="2068" CreationDate="2014-02-21T16:15:48.330" Score="22" ViewCount="2595" Body="&lt;p&gt;I live in the US, near a fairly dangerous road, and I've called 911 a few times to report car accidents outside my home.  It's a lot like giving a PIREP - you give the necessary information and the appropriate help is dispatched.  All very simple and clean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never heard of anyone calling 866-GA-SECURE.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What happens when you do?&lt;/strong&gt;  Who do you talk to?  Who responds?  How fast is the response?  What can you expect?&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="3201" LastEditDate="2015-09-21T06:00:51.820" LastActivityDate="2015-09-21T06:00:51.820" Title="What happens when you call 866-GA-SECURE in the US?" Tags="&lt;security&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1855" PostTypeId="1" AcceptedAnswerId="1856" CreationDate="2014-02-21T17:15:37.437" Score="15" ViewCount="8839" Body="&lt;p&gt;Many commercial airliners have car-like window-wipers. I would presume this is for taxiing only, as the wind would surely keep the windows free from water when airborne,  or do they turn them on in flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, don't these wipers cause a lot of drag, and wouldn't it be more economical to have some kind of air-jet blowing from nozzles to keep the windshield clear?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="1696" LastEditDate="2015-10-07T14:37:31.800" LastActivityDate="2015-10-07T14:37:31.800" Title="Are the window wipers on jet aircraft ever deployed in flight?" Tags="&lt;safety&gt;&lt;wind&gt;&lt;windows&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1856" PostTypeId="2" ParentId="1855" CreationDate="2014-02-21T17:44:38.463" Score="16" Body="&lt;p&gt;In the Falcon 50 and 900, we have windshield wipers that we are &lt;strong&gt;allowed&lt;/strong&gt; to use in flight (up to 205 KIAS), but I have never used or seen them used in the eight years that I have been flying them because they simply aren't needed.  They are usually stowed out of the wind stream so don't really cause much drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Learjet's on the other hand DO have hot air that blows on the windshield and we sometimes used it to blow water droplets off of the windshield when on the ground.  However, the primary purpose of the hot air was to heat and defog the windshield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a larger airplane, the additional piping, valves, etc. required to get the hot air all of the way up to the windshield actually weighs and costs more than just putting the windshield wipers up there along with electrically heated windshields to keep them from fogging up.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-22T21:00:57.277" LastActivityDate="2014-02-22T21:00:57.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1857" PostTypeId="1" AcceptedAnswerId="1859" CreationDate="2014-02-21T17:58:58.177" Score="34" ViewCount="6871" Body="&lt;p&gt;Before  WWII, flying boats were a popular form of transport, and the advantages are many: No need to build runways, capability of emergency landing on water, availability of large landing sites and no tire wear and tear. Why have they been abandoned?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="39" LastEditDate="2014-02-21T18:40:56.087" LastActivityDate="2021-01-02T00:49:56.557" Title="Why were flying boats phased out?" Tags="&lt;airline-operations&gt;&lt;landing-gear&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1858" PostTypeId="1" AcceptedAnswerId="1860" CreationDate="2014-02-21T18:17:21.050" Score="5" ViewCount="1144" Body="&lt;p&gt;This question has several parts that are interrelated, and I didn't want to split it up:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering that several tons of fuel are consumed during a long haul flight which requires lift to be reduced as the flight progresses, do pilots do this by changing wing geometry, altitude, speed or all of the above?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this done automatically or manually?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the optimal strategy if you want to minimize fuel costs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having chosen the optimal strategy, is the latest phase of the flight where the airplane weighs least necessarily the one that gets the best gas mileage, or is there a minimum at a certain intermediate airplane mass during the flight?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2014-02-24T09:24:42.897" Title="At what point during a long flight do commercial airliners have the best gas mileage?" Tags="&lt;fuel&gt;&lt;cost&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1859" PostTypeId="2" ParentId="1857" CreationDate="2014-02-21T18:40:35.443" Score="39" Body="&lt;p&gt;The biggest single reason for the decline of flying boats was the proliferation of long runways during World War II. The infrastructure advantage of flying boats – the ability to operate heavy aircraft without long runways – was no longer relevant. Large airfields were a result of the long-range heavy bomber campaigns in Europe and Asia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Century of Flight has &lt;a href=&quot;http://www.century-of-flight.net/Aviation%20history/coming%20of%20age/flying%20boats/flying_boat.htm&quot;&gt;an interesting article&lt;/a&gt; that goes a bit more in depth.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-02-21T18:40:35.443" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1860" PostTypeId="2" ParentId="1858" CreationDate="2014-02-21T19:36:40.327" Score="5" Body="&lt;p&gt;There are a lot of things that go into determining the most efficient way to operate a jet, and minimizing fuel does not always make it cheaper to operate.  Some general &quot;rules&quot; that are used are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is an optimum speed to fly the airplane, which depends on several factors:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Altitude&lt;/li&gt;&#xA;&lt;li&gt;Fuel savings by flying slower -vs- increased maintenance costs because you are taking longer to get there (and putting more time on the airframe/engines).&lt;/li&gt;&#xA;&lt;li&gt;Temperature at cruising altitude&lt;/li&gt;&#xA;&lt;li&gt;Winds at cruising altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;There is also an optimum altitude to fly the airplane:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft weight&lt;/li&gt;&#xA;&lt;li&gt;The higher that you can fly, the better - until you don't have enough power to maintain your optimum speed at the optimum power setting for the engines.&lt;/li&gt;&#xA;&lt;li&gt;Temperature at cruising altitude&lt;/li&gt;&#xA;&lt;li&gt;Winds at cruising altitude&lt;/li&gt;&#xA;&lt;li&gt;Altitudes that are available from ATC&lt;/li&gt;&#xA;&lt;li&gt;The amount of fuel and time that it takes to climb -vs- the amount of time that you will have at the high speed cruise&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Anything that makes the airplane heavier makes it unable to climb as high (and lowers the optimum altitude for the current conditions), and makes it burn more fuel.  This includes the fuel itself.  Assuming a constant speed and constant weather conditions, you will always be more fuel efficient later in the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As fuel gets burned off, the amount of thrust required to maintain the optimum speed goes down and the optimum altitude goes up.  Basically, we keep reducing the power to maintain speed until the optimum altitude increases to an altitude that ATC can let us climb to.  This is known as a step climb.  The speed will be controlled manually by the pilot, or can be controlled automatically by auto throttles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today's sophisticated flight planning software takes all of this into account and gives the pilot a very good plan on how to operate the airplane to be the most efficient!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-21T19:36:40.327" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1862" PostTypeId="1" CreationDate="2014-02-22T02:23:01.420" Score="2" ViewCount="2664" Body="&lt;p&gt;It seems that you would use full power for takeoffs, but when I have heard of airline pilots using less than full power on takeooff. Wouldn't it be safer to use full throttle?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-02-22T02:23:01.420" Title="Why don't airliners use full throttle on takeoff?" Tags="&lt;takeoff&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-02-22T03:14:34.913" ContentLicense="CC BY-SA 3.0" />
  <row Id="1863" PostTypeId="2" ParentId="1857" CreationDate="2014-02-22T04:52:48.653" Score="10" Body="&lt;p&gt;The second biggest reason:  Where would they land in Denver?  And many more cities that have robust air traffic but not many lakes or waterways that are suitable. &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-02-22T04:52:48.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1864" PostTypeId="2" ParentId="1857" CreationDate="2014-02-22T09:48:27.773" Score="31" Body="&lt;p&gt;Apart logistics and the availability of long runways afterr WWII, the reason for the phasing out of the sea planes was &lt;strong&gt;maintenance&lt;/strong&gt;. The aircraft was operating in an extremely &lt;strong&gt;corrosive&lt;/strong&gt; environment, something that can be seen nowadays in the firefighting planes like the Canadair and other smaller seaplanes. More info: &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43-4B.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Corrosion Control&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Also the engines need to be inspected and cleaned after every operation. Generally speaking, operation in corrosive environments like water is something that requires very careful inspection and time consuming maintenance. For example even the Chinook helicopter needs extensive cleaning after operations that involve &lt;a href=&quot;http://www.youtube.com/watch?v=OHfyJ-ewlAU&quot; rel=&quot;noreferrer&quot;&gt;landing on water&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Finally the increased &lt;strong&gt;drag&lt;/strong&gt; due to the shape of the flying boat is something that every designer and airliner wants to avoid.&lt;/p&gt;&#xA;" OwnerUserId="376" LastEditorUserId="376" LastEditDate="2021-01-02T00:49:56.557" LastActivityDate="2021-01-02T00:49:56.557" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="1865" PostTypeId="1" AcceptedAnswerId="1875" CreationDate="2014-02-22T11:12:35.313" Score="5" ViewCount="1618" Body="&lt;p&gt;I thought that you had to perform all your ATPL multi-crew time in aircraft with a certificated minimum of 2 crew, but I've heard of some pilots using time in single-pilot aircraft towards their EASA ATPL licence. Is this true? If so, could someone explain how is this possible?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="69" LastEditDate="2014-02-22T23:09:33.563" LastActivityDate="2014-02-23T02:01:28.410" Title="Are multi-crew operations in a single-pilot aircraft counted towards ATPL requirements?" Tags="&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1866" PostTypeId="1" AcceptedAnswerId="1867" CreationDate="2014-02-22T11:31:10.527" Score="16" ViewCount="17650" Body="&lt;p&gt;I  observed that the cockpit windows on the commercial airliners actually open - good for a hot day while waiting on the airfield, I suppose. Is there a mechanism which prevents the window from being opened when airborne? &lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="1696" LastEditDate="2015-10-07T14:35:43.693" LastActivityDate="2020-01-15T22:10:36.217" Title="Can the cockpit windows on commercial airliners open during flight?" Tags="&lt;safety&gt;&lt;windows&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1867" PostTypeId="2" ParentId="1866" CreationDate="2014-02-22T11:36:38.537" Score="18" Body="&lt;p&gt;I'm sure that the cabin pressure difference prevents this at altitude when the cabin is pressurized, due that they often slide inwards and then to the side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, Boeing &lt;a href=&quot;http://www.youtube.com/watch?v=NQZzTPd1HJw&quot;&gt;produced a video&lt;/a&gt; showing that it's no problem flying with an open window on the 737 if say it opens on takeoff. You can close it assuming it's not damaged or you can land with it. They also showed that the &lt;strong&gt;side window can be opened in flight&lt;/strong&gt; in case for instance visibility is impaired through the main window, and while it hardly looks comfortable, it can be done. This assumes that the cabin is unpressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sort of thing you might be thinking about is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cooper_vane&quot;&gt;cooper vane&lt;/a&gt;, but I don't think any aircraft have those on the cockpit windows.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-22T11:52:31.397" LastActivityDate="2014-02-22T11:52:31.397" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1868" PostTypeId="2" ParentId="1866" CreationDate="2014-02-22T15:49:33.183" Score="2" Body="&lt;p&gt;It depends on the airplane, and there are speed limits on the ones that can be open.  The windows on mine can be open up to 140 knots, but that is barely flying speed so it's really not practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Naturally, you can't be pressurized if you have a window open.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-02-22T15:49:33.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1869" PostTypeId="1" AcceptedAnswerId="1870" CreationDate="2014-02-22T18:16:15.843" Score="9" ViewCount="9054" Body="&lt;p&gt;If I were to redo my avionics to only include a WAAS GPS unit and two comm radios, &lt;strong&gt;would anything prevent me from operating IFR?&lt;/strong&gt; 14 CFR 91.205(d) only states that my airplane must have:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) Two-way radio communication and navigation equipment suitable for the route to be flown.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm aware that this is not the most bulletproof way to fly hard IFR. In this case, assume that the aircraft is primarily used for currency/proficiency and the occasional light IFR flight.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="72" LastEditDate="2014-03-03T05:26:23.680" LastActivityDate="2014-03-03T05:26:23.680" Title="Can an aircraft operate IFR without ground-based navigation?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1870" PostTypeId="2" ParentId="1869" CreationDate="2014-02-22T18:49:53.947" Score="10" Body="&lt;p&gt;The AIM contains the information required to operate under IFR using GPS&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarize the requirements,  WAAS (but not &quot;traditional&quot; GPS) may be used stand-alone without an alternate means of navigation provided:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Installation requirements:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The WAAS navigation equipment is approved in accordance with TSOC145 or TSOC146&lt;/li&gt;&#xA;&lt;li&gt;The installation is done in accordance with AC 20-138&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Operational Requirements:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The WAAS AFM procedures are followed&lt;/li&gt;&#xA;&lt;li&gt;It is not be used by a commercial operator&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Preflight Requirements:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The GPS database is current&lt;/li&gt;&#xA;&lt;li&gt;The GPS database provider does not have any notices prohibiting the use of any fix or procedure that you are going to use&lt;/li&gt;&#xA;&lt;li&gt;GPS NOTAMs/Aeronautical Information is reviewed prior to each flight &lt;/li&gt;&#xA;&lt;li&gt;A RAIM prediction for the time and route is done that shows no loss of RAIM&lt;/li&gt;&#xA;&lt;li&gt;The flight plan navigation equipment is listed as RNAV&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that commercial operators are required to have redundant systems or ground based backups in order to use it, and while not required for you, it's a pretty good idea.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; More specifically, see:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html#aim0101.html.25&quot;&gt;&lt;strong&gt;AIM Chapter 1, Section 1 - Navigation Aids&lt;/strong&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1-1-18. Global Positioning System (GPS)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;d. General Requirements&lt;/li&gt;&#xA;&lt;li&gt;e. Use of GPS for IFR Oceanic, Domestic En Route, Terminal Area, and Approach &#xA;Operations&lt;/li&gt;&#xA;&lt;li&gt;f. General Database Requirements&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;1-1-19. Wide Area Augmentation System (WAAS)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;c. General Requirements&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-22T19:43:01.130" LastActivityDate="2014-02-22T19:43:01.130" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1871" PostTypeId="2" ParentId="1855" CreationDate="2014-02-22T20:57:47.820" Score="13" Body="&lt;p&gt;In the EMB-145 we could use the wipers below 170 KIAS. Wipers are really only useful on or near the ground, so this was not a limitation that really mattered.  Our windscreen wasn't the best at deflecting rain, so in heavy precip we would use them inside the FAF when looking for lights/the runway and during taxi to the gate.  On departure we would use them in heavy precip to taxi and takeoff, turning them off in the after takeoff flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airplanes, as Lnafziger points out have better flow characteristics over the windscreen or blown air and are not equipped with wipers.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any airplane, the wipers are only potentially useful for ground ops, takeoffs and landings and serve no purpose at altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the wipers, we were also equipped with an electric defroster to keep the windscreen free of fog and ice, and this was used during the descent from cruise to landing.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-22T20:57:47.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1872" PostTypeId="1" CreationDate="2014-02-22T21:39:53.453" Score="10" ViewCount="14153" Body="&lt;p&gt;Not all airplanes with passengers are required to have flight attendants.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the regulations that cover this and when are they required?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-23T03:02:28.737" Title="Under what conditions is a flight attendant required on an aircraft?" Tags="&lt;faa-regulations&gt;&lt;flight-attendant&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1873" PostTypeId="1" CreationDate="2014-02-22T21:54:22.770" Score="12" ViewCount="6007" Body="&lt;p&gt;Some &quot;ILS or LOC&quot; approaches have crossing restrictions that are shown before and/or after the final approach fix/glideslope intercept.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these restrictions for the LOC only approach, or do they also apply when tracking the glideslope?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, KSFO ILS 28L and KSFO ILS 19L (see below) both have crossing restrictions before and after glideslope intercept. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the fixes after intercept though, notice that NEPIC does not have a '*' next to the crossing restriction (which means &quot;LOC only&quot;) while ROGGE does:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q7xKZ.png&quot; alt=&quot;KSFO ILS 28L&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Drfoi.png&quot; alt=&quot;KSFO ILS 19L&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-23T00:17:24.480" LastActivityDate="2019-06-08T17:21:21.933" Title="Are crossing restrictions on an ILS/LOC approach mandatory when flying on the glideslope?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;&lt;terps&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1874" PostTypeId="1" AcceptedAnswerId="1887" CreationDate="2014-02-22T22:19:03.400" Score="8" ViewCount="344" Body="&lt;p&gt;ICAO issues recommendations/rules/statutes/something? that standardizes the regulations for international air travel world-wide.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are these &quot;rules&quot; officially called and where can they be found?  Are they available on the internet?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-09-02T11:34:41.620" LastActivityDate="2016-09-02T11:34:41.620" Title="Where can the ICAO recommendations be found?" Tags="&lt;icao&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1875" PostTypeId="2" ParentId="1865" CreationDate="2014-02-22T22:23:00.007" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=2725&amp;amp;pagetype=65&amp;amp;appid=54&amp;amp;mode=detail&amp;amp;appproc=63&quot; rel=&quot;nofollow&quot;&gt;According to the UK CAA&lt;/a&gt; you need:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;500 hours in multi-pilot &lt;strong&gt;operations&lt;/strong&gt; on aeroplanes;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notice that it does not say anything about the &lt;strong&gt;aircraft&lt;/strong&gt; being multi-pilot/certified for two crew members.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An air carrier can specify in their ops manuals that, for their operations, they require a particular airplane to be operated with two crew members even if it is only type certificated for one crew member.  If their manual is approved, then it is now a &quot;multi-pilot operation&quot; regardless of the type-certification status of the airplane.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-23T02:01:28.410" LastActivityDate="2014-02-23T02:01:28.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1876" PostTypeId="2" ParentId="1873" CreationDate="2014-02-22T23:16:10.200" Score="4" Body="&lt;p&gt;At the very beginning of my answer, I would like to remind that everyone should be familiar with the type of charts he is using. A &lt;a href=&quot;https://aeronav.faa.gov/content/aeronav/online/pdf_files/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow&quot;&gt;thorough description&lt;/a&gt; (PDF) of all charts published by the FAA is available on this &lt;a href=&quot;https://aeronav.faa.gov/index.asp?xml=aeronav/applications/digital/aero_guide&quot; rel=&quot;nofollow&quot;&gt;FAA website&lt;/a&gt;. Refer to page 77 of the PDF document to find the altitudes your question is dealing with. On every flight, you make decisions based on the information you read from those charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, once you are cleared for an ILS approach and have intercepted the glidepath in accordance with your clearance, your task is to track the localizer and glideslope, allowing not more than a half-scale deflection, until reaching your DA (or DH on CAT II and III approaches). The exact altitude reading at which the glideslope passes over a specific point is as variable as air density is. This might cause you to be more than 20 feet below the minimum altitudes, but it doesn't matter as all of them past the FAP are for non-precision approaches only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how it's handled in the US, also the FAA is using the term FAF - Final Approach Fix - talking about ILS approaches. Technically this is wrong, because the point where you hit the glidepath at a certain altitude is variable - remember the air density. That's why we should talk about a FAP - Final Approach Point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, those altitudes should be used when shooting an ILS approach in order to make sure that you didn't fly a side lobe of the glideslope - even if the chances to find one are very remote. On Jeppesen charts you find this 'check altitudes' above the depicted glidepath often at the outer marker (if available) preceeded by the letters GS. On FAA charts these are referred to as recommended altitudes. Find them for example on the chart for the ILS runway 28L approach attached to the question. They are also printed above the glideslope but not underlined, as they are recommended but not mandatory / minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an ILS approach where you are tracking the localizer, but not the glideslope, because you are too far out and below it, or do not receive it. For example at HEMAN 3100' are important if ATC already cleared you for the approach and you like to descend below the last cleared (maintain xxx feet until established on...) altitude. The latest point where you have to intercept the glide slope is the FAP (FAF according to FAA) but if it is not disagreeing with your clearance you can of course get on glideslope earlier. In this case, prior to the FAP, this minimum altitude is then still mandatory for you (to be at or above) because of reduced glideslope precision at higher distances (it's a cone not a string), but I've never seen someone getting below those minima flying the glide path. In most cases the glideslope will take you quite above these altitudes and you have a continuous and more economic descent into your runway, rather than doing a stepped descent allways being at the minima.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who like to take a closer look at Jeppesen's charts, visit &lt;a href=&quot;http://ww1.jeppesen.com/aviation/business/additional-info-ifr-paper-services.jsp&quot; rel=&quot;nofollow&quot;&gt;their website&lt;/a&gt; to find the &lt;a href=&quot;http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/glossary-legends.pdf&quot; rel=&quot;nofollow&quot;&gt;chart legend&lt;/a&gt; (PDF) - take a look at page 55 of this document. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="2171" LastEditDate="2014-05-30T17:25:22.997" LastActivityDate="2014-05-30T17:25:22.997" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1877" PostTypeId="1" CreationDate="2014-02-22T23:52:20.537" Score="22" ViewCount="7500" Body="&lt;p&gt;How does Identification Friend or Foe (IFF) work? Are radar images of friendly planes recorded, or do friendly planes have transponders on them?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="19" LastEditDate="2014-02-23T03:39:01.313" LastActivityDate="2014-04-07T02:55:31.500" Title="How does IFF work?" Tags="&lt;radar&gt;&lt;military&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1878" PostTypeId="1" AcceptedAnswerId="1890" CreationDate="2014-02-23T00:06:04.230" Score="13" ViewCount="757" Body="&lt;p&gt;Can St. Elmo's Fire on an aircraft cause instruments to fail or give erratic readings, primarily with glass cockpits? Are there backup instruments that would not be affected? Does it affect radio transmissions?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="72" LastEditDate="2014-02-23T03:22:51.060" LastActivityDate="2014-02-24T04:53:01.510" Title="Can St. Elmo's Fire cause instruments to fail?" Tags="&lt;radio-communications&gt;&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1879" PostTypeId="2" ParentId="1877" CreationDate="2014-02-23T00:19:36.007" Score="19" Body="&lt;p&gt;IFF systems use a transponder/interrogator combination to allow aircraft to issue challenges, receive responses, and do the friend or foe test. BAE Systems has a &lt;a href=&quot;http://www.baesystems.com/our-company-rus/inc-businesses/electronic-systems/es-product-sites/identification-friend-or-foe-iff/iff-transponders&quot;&gt;transponder product page&lt;/a&gt; with a little info, and Wikipedia (yeah yeah) has a &lt;a href=&quot;http://en.wikipedia.org/wiki/Identification_friend_or_foe&quot;&gt;reasonably thorough description and history of IFF&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://engineers.ihs.com/document/abstract/KTVQSAAAAAAAAAAA&quot;&gt;NATO STANAG 4579&lt;/a&gt; (abstract):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This NATO BRID is a millimetric wave question and answer system working in the Ka band. It comprises two main components, an &lt;strong&gt;interrogator, which allows a platform to question another platform with an encrypted message&lt;/strong&gt;, and a &lt;strong&gt;transponder, which decodes the message and replies with an encrypted answer&lt;/strong&gt; [&lt;em&gt;emphasis mine&lt;/em&gt;]. Transponders will be fitted to all designated platforms, while interrogators will be fitted to only those designated platforms with an offensive or reconnaissance capability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-02-23T00:28:47.717" LastActivityDate="2014-02-23T00:28:47.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1880" PostTypeId="1" AcceptedAnswerId="1881" CreationDate="2014-02-23T02:10:56.027" Score="11" ViewCount="4126" Body="&lt;p&gt;Reading &lt;a href=&quot;http://airtravel.about.com/od/travelindustrynews/tp/Readers-Digest-50-Secrets-Your-Pilot-Wo-Not-Tell-You.htm&quot;&gt;this page&lt;/a&gt;, a retired American Airlines pilot quotes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We tell passengers what they need to know. We don’t tell them things that are going to scare the pants off them. So you’ll never hear me say, ‘Ladies and gentlemen, we just had an engine failure,’ even if that’s true.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Given this, how can an observant passenger sitting over wing (seeing most likely very little of the engine), determine if a flameout or shutdown has occurred from observation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is applicable to an aircraft not unlike the Boeing 737 (which I fly on often).&lt;/p&gt;&#xA;" OwnerUserId="743" LastEditorUserId="69" LastEditDate="2014-02-23T02:29:22.803" LastActivityDate="2014-02-23T03:05:37.593" Title="How can a passenger tell if a flame-out / engine failure has occurred?" Tags="&lt;jet-engine&gt;&lt;passenger&gt;&lt;boeing-737&gt;&lt;engine-failure&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1881" PostTypeId="2" ParentId="1880" CreationDate="2014-02-23T02:28:33.410" Score="16" Body="&lt;p&gt;Mainly by the soon to happen descent and landing, probably at a place you weren't expecting to go.  :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are seated behind the wing, you &lt;strong&gt;might&lt;/strong&gt; be able to see smoke or flames coming out of the engine, but other times it will just quit with no visible indicaion, depending on the cause of the failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sometimes&lt;/strong&gt; (usually just after takeoff when the airplane is slow) it is obvious and you can tell by the change in the sound of the airplane (one side suddenly gets quiet or there &lt;strong&gt;might&lt;/strong&gt; be a loud bang depending on why it failed), a sudden yaw in one direction (the nose pulls to one side), and an abrupt pitching down of the nose (done by the pilot to maintain flying speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other times (like during a descent with plenty of speed and the engines at idle, or when the center engine of a three engine airplane fails) it can be hard for even the pilot to tell without looking at the instrumentation, so you probably won't notice it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another major clue would be when the seatbelt sign unexpectedly coming on, without an announcement or indication of turbulence, and the flight attendants suddenly putting things away and getting ready for landing, especially when you aren't close to your destination. Being briefed for an emergency landing is also a dead giveaway (no pun intended).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-23T03:05:37.593" LastActivityDate="2014-02-23T03:05:37.593" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="1882" PostTypeId="2" ParentId="1872" CreationDate="2014-02-23T02:50:37.837" Score="12" Body="&lt;p&gt;14 CFR Part § 121.391.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on the size/weight of the airplane and how many passengers it can hold&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except as specified in § 121.393 and § 121.394, each certificate&#xA;  holder must provide at least the following flight attendants on board&#xA;  each passenger-carrying airplane when passengers are on board: &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;For airplanes having a maximum payload capacity of more than 7,500 pounds&#xA;  and having a seating capacity of more than 9 but less than 51&#xA;  passengers—&lt;strong&gt;one flight attendant.&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;For airplanes having a maximum&#xA;  payload capacity of 7,500 pounds or less and having a seating capacity&#xA;  of more than 19 but less than 51 passengers—&lt;strong&gt;one flight attendant&lt;/strong&gt;. &lt;/li&gt;&#xA;  &lt;li&gt;For airplanes having a seating capacity of more than 50 but less than&#xA;  101 passengers—&lt;strong&gt;two flight attendants&lt;/strong&gt;.&lt;/li&gt;&#xA;  &lt;li&gt;For airplanes having a seating capacity of more than 100 passengers—&lt;strong&gt;two flight &#xA;  attendants plus one additional flight attendant for each unit (or part of a unit)&#xA;  of 50 passenger seats above a seating capacity of 100 passengers&lt;/strong&gt;.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/pdf/CFR-2011-title14-vol3-sec121-391.pdf&quot;&gt;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/pdf/CFR-2011-title14-vol3-sec121-391.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parts § 121.393,394 relax these requirements when a plane stops, but denotes how close by the flight attendants must be, and other things like exit door requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, Flight Attendants are there for your safety :) which is the motivation for these regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Edit]&#xA;14 CFR Part 91.533 covers flights operated under &quot;Part 91&quot; regulations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;§ 91.533 Flight attendant requirements.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;No person may operate an airplane unless at least the following number of flight attendants are on board the airplane:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;For airplanes having more than 19 but less than 51 passengers on board, one flight attendant.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;For airplanes having more than 50 but less than 101 passengers on board, two flight attendants.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;For airplanes having more than 100 passengers on board, two flight attendants plus one additional flight attendant for each unit (or part&#xA;  of a unit) of 50 passengers above 100.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;No person may serve as a flight attendant on an airplane when required by paragraph (a) of this section unless that person has&#xA;  demonstrated to the pilot in command familiarity with the necessary&#xA;  functions to be performed in an emergency or a situation requiring&#xA;  emergency evacuation and is capable of using the emergency equipment&#xA;  installed on that airplane.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like the &quot;training&quot; to act as a Part 91 Flight Attendant is just showing the pilot they are capable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big difference between Part 121 and Part 91, is &lt;em&gt;number of seats (potential capacity)&lt;/em&gt; vs. &lt;em&gt;people actually on board&lt;/em&gt;.  This is interesting in light of the recent 787 Boeing Business Jet deliveries (&lt;a href=&quot;http://boeing.mediaroom.com/2014-02-05-Boeing-Business-Jets-Delivers-First-Two-BBJ-787-8s-of-2014&quot;&gt;http://boeing.mediaroom.com/2014-02-05-Boeing-Business-Jets-Delivers-First-Two-BBJ-787-8s-of-2014&lt;/a&gt;).  So if it was just the owner and the pilot crew, there wouldn't need to be a flight attendant (assuming, of course, they're operating under Part 91), even though it is a huge plane.&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="132" LastEditDate="2014-02-23T03:02:28.737" LastActivityDate="2014-02-23T03:02:28.737" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1883" PostTypeId="1" AcceptedAnswerId="1888" CreationDate="2014-02-23T09:57:35.510" Score="22" ViewCount="27409" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/TCAS&quot;&gt;TCAS&lt;/a&gt; is obviously a fantastic piece of kit, but I was wondering: exactly how does it work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I mean is, how does it determine whether to tell a pilot to climb or descend when there's traffic?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, can you give an overview of the various types of TCAS, and how planes agree a resolution?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2017-10-06T13:29:41.180" Title="How does TCAS work?" Tags="&lt;safety&gt;&lt;tcas&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1884" PostTypeId="5" CreationDate="2014-02-23T10:17:47.720" Score="0" Body="&lt;p&gt;A &lt;em&gt;traffic collision avoidance system&lt;/em&gt;, or &lt;em&gt;traffic alert and collision avoidance system&lt;/em&gt;, (both abbreviated as TCAS and pronounced &lt;em&gt;tee-kas&lt;/em&gt;) is a system designed to reduce mid-air collisions between aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS units use transponder signals to gather information about nearby aircraft. If two aircraft are on a collision course, their TCAS units communicate with other to negotiate an avoidance plan, e.g. one aircraft climbs and the other descends. The unit then alerts the crew with a spoken warning or instruction such as &quot;climb, climb!&quot;. Crews are required to follow the TCAS instruction immediately, even if ATC has given other instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO mandates TCAS for all aircraft that have a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or are authorized to carry more than 19 passengers.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wikipedia: &lt;a href=&quot;https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Traffic collision avoidance system&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="62" LastEditDate="2016-11-22T21:28:31.713" LastActivityDate="2016-11-22T21:28:31.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1885" PostTypeId="4" CreationDate="2014-02-23T10:17:47.720" Score="0" Body="Traffic Collision Avoidance Systems warn pilots about other, nearby aircraft that may be a collision risk" OwnerUserId="97" LastEditorUserId="62" LastEditDate="2016-11-22T21:23:22.357" LastActivityDate="2016-11-22T21:23:22.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1886" PostTypeId="2" ParentId="1873" CreationDate="2014-02-23T10:35:37.403" Score="6" Body="&lt;p&gt;Closest regulatory thing I could find :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO Doc 8168 Section 4 Arrival and approach procedures&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.7.5 Any constant descent angle &lt;strong&gt;shall&lt;/strong&gt; clear all stepdown fix minimum crossing altitudes within any segment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.5.1 A &lt;strong&gt;stepdown&lt;/strong&gt; fix &lt;strong&gt;may&lt;/strong&gt; be incorporated in some &lt;strong&gt;non-precision&lt;/strong&gt; approach procedures&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.5.5.2    The  protection  area  assumes  that  the  pilot  does  not  normally  deviate  from  the  centre  line  more  than  half-scale &#xA;  deflection  [...]   more  than  half  course  fly-up [...]  could &#xA;  place  the  aircraft  in  [...] airspace where loss of protection from&#xA;  obstacles can occur.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The writing leads me to believe that a precision approach &lt;strong&gt;should&lt;/strong&gt; not contain stepdown fixes, and that the descent &lt;strong&gt;should&lt;/strong&gt; be a continuous descent from FAP to MAP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then again, I could find nothing specific to prevent anyone from inserting an altitude restriction in a precision approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot imagine what would be the point of coming down on a constant GS only to level off at 1000' then try to re-capture the GS just two miles from thouchdown. Talk about a stable approach...&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-02-23T10:46:22.920" LastActivityDate="2014-02-23T10:46:22.920" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1887" PostTypeId="2" ParentId="1874" CreationDate="2014-02-23T11:47:49.510" Score="9" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;ICAO publishes and maintains &lt;strong&gt;19 Annexes&lt;/strong&gt; to the Chicago Convention. They pertain to all matters in aviation and provide the framework for national legislation in each of the member countries in the form of &lt;strong&gt;Standards and Recommended Practices&lt;/strong&gt; (SARP).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In addition to the 19 Annexes, ICAO also produces more detailed guidance in the form of &lt;strong&gt;Procedures for Air Navigation Services&lt;/strong&gt; (PANS): PANS-ABC, PANS-OPS, PANS-ATM. These are also usually referenced by their Doc number: 2007, 8168, 4444, etc&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In addition to the PANS, for specific regions of the world ICAO publishes &lt;strong&gt;Regional Supplementary Procedures&lt;/strong&gt; (SUPP) to incorporate regional variants/requirements.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Any ICAO contracting state may have local legislation different from SARP/PANS, but is obliged to notify ICAO of these differences. You will find these differences in the country's AIP section GEN.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting electronic copies of these documents is a bit more difficult.  ICAO &lt;a href=&quot;http://store1.icao.int/&quot;&gt;sells these documents&lt;/a&gt; for a very 'aviation' price. Some CAA's and institutions will provide &lt;a href=&quot;http://dcaa.trafikstyrelsen.dk:8000/icaodocs/&quot;&gt;electronic copies in PDF form&lt;/a&gt;, but they will most likely be out of date and their legality is suspicious at best. Welcome to the world of international law.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-02-23T11:47:49.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1888" PostTypeId="2" ParentId="1883" CreationDate="2014-02-23T21:29:21.227" Score="21" Body="&lt;p&gt;TCAS works by sending interrogations to other aircraft's transponders. The transponder will reply to the interrogation in a similar way it responds to radar. From the time difference between the interrogation and the reply, the distance to the other aircraft is calculated. The reply itself contains the altitude of the other aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The explanation below gives an insight in the basic working of the TCAS algorithm. In reality it is more complex to deal with all kinds of exceptional situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The distance and the altitude difference with the other aircraft is tracked to identify a trend. From successive distance measurements the closure rate is determined. With the closure rate and the current distance (slant range) an approximation is made of the time to the closest point of approach (CPA). This is done by simply dividing the range by the closure rate, the result is called 'range tau'. The same is done in the vertical plane. Dividing the difference in altitude by the vertical speed difference leads to the vertical tau.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both tau's are less than certain threshold, a Traffic Alert (TA) is raised. When the tau's are less that another (lower) threshold, a Resolution Advisory is given. The TA is a 'heads up' indication, the RA is an instruction that must be followed by the pilot to reduce the collision risk. &#xA;The threshold times depend on the altitude, ranging from 20 seconds (&amp;lt;1000 ft AGL) to 48 seconds (&gt; FL200) for TA's and from 15 seconds (&amp;lt;2350 ft) to 35 seconds (&gt; FL200) for RA's. Below 1000 ft AGL, RA's are inhibited. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally TCAS did only give Traffic Advisories in the form of a &quot;Traffic, traffic&quot; annunciation. There was no avoiding action indicated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the introduction of TCAS II in the second half of the '80s the Resolution Advisory made its entrance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;RA selection&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In selecting a resolution advisory, there are two basically two steps. The first step is to select a sense, either upward or downward. This is based on a calculation of how much altitude difference can be achieved at the CPA by either starting a climb or descent, assuming the target will maintain its vertical rate. In the calculation the reaction time of the crew and acceleration and climb / descent rate of the aircraft is assumed (5 seconds, 0.25g, 1500 fpm).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second step is to select a magnitude. The algorithm is designed to be the least disruptive to the flight path, whilst still achieving a minimum vertical separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;RA coordination&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a RA is selected, it is transmitted to the other aircraft. When the other aircraft receives that message, it will only use the opposite sense for its own RA. In the rare case that both aircraft transmit their RA intent at the same time, the aircraft with the higher Mode S address will give in and reverse its RA sense if it is conflicting with the other. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Algorithm versions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the years various improvements are made to TCAS II. The initial TCAS II systems had version 6.0 of the algorithm, later replaced by 6.04a in the mid 90's. Further system evaluation lead to the development of version 7.0, implemented from 1999. Following a near mid-air collision in Japan in 2001 and a mid-air collision over Uberlingen, Germany further changes were made leading to version 7.1. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changes that were made include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the wording of the RA's &lt;/li&gt;&#xA;&lt;li&gt;logic to limit the vertical path deviations&lt;/li&gt;&#xA;&lt;li&gt;logic to prevent nuisance alerts in RVSM airspace and on closely spaced parallel runway operations&lt;/li&gt;&#xA;&lt;li&gt;logic to detect non-compliance to an RA&lt;/li&gt;&#xA;&lt;li&gt;improved RA sense reversal logic&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS &amp;amp; ATC&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS RA's take precedence of ATC instructions. The fact that one of the two aircraft followed ATC instructions, and the other TCAS RA's contributed to the Uberlingen accident. &#xA;In case a pilot is getting a TCAS RA he should notify ATC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;==========&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has produced an &lt;a href=&quot;https://www.faa.gov/documentlibrary/media/advisory_circular/tcas%20ii%20v7.1%20intro%20booklet.pdf&quot; rel=&quot;noreferrer&quot;&gt;Intro into TCAS II v7.1&lt;/a&gt; which provided some interesting reading on the topic.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="5517" LastEditDate="2017-10-06T13:29:41.180" LastActivityDate="2017-10-06T13:29:41.180" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1889" PostTypeId="2" ParentId="1883" CreationDate="2014-02-23T21:44:15.843" Score="6" Body="&lt;p&gt;The TCAS standard uses the standard &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_(aviation)&quot; rel=&quot;nofollow&quot;&gt;transponder&lt;/a&gt;, having the interrogator on board in addition to the transponder itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft periodically broadcasts the interrogation signal. The power is less than from the ground radar, but sufficient to trigger response from aircraft that may be less than a minute of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The distance to the other aircraft is determined from the timing the signal, closure rate from two consecutive measurements of distance and pressure altitude is part of the transponder response. Position can only be determined approximately by using directional antenna, so it is only used for showing the other aircraft on the nav display, but &lt;em&gt;not&lt;/em&gt; for determining the resolution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system activates if the closure rate is such that collision could possibly happen in some specific time. That does not mean that the aircrafts are actually on colliding courses; the TCAS system does not evaluate headings or positions. It is just that the momentary closure rate is high enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft could collide in 40 seconds, the system gives out a &quot;Traffic Advisory&quot;. This is just a warning that there is a nearby traffic and that an action may need to be taken soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the distance reduces so that the risk of collision gets to 25 seconds, a &quot;Resolution Advisory&quot; will be given. This is an instruction to climb, descend, climb/descend faster or level out. The pilot is required to comply in 6 seconds, the instruction has priority over ATC instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which advisory to give is derived by a set of rules from altitude and rate of climb of this and the other aircraft. Since the altitude is sent in the transponder response and rate of climb is simply difference of consecutive altitude measurements, both TCAS have the same information and therefore will always come to the same conclusion. Basically it will tell whichever aircraft is higher to climb, climb faster, or if descending to not descend and whichever is lower to descend, descend faster or if climbing to not climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also similar system for light aircraft called &lt;a href=&quot;http://en.wikipedia.org/wiki/FLARM&quot; rel=&quot;nofollow&quot;&gt;FLARM&lt;/a&gt;. The principle is similar. It uses lower power radios, because gliders and ultra-lights don't have enough power for the standard transponder. It's messages also include position and heading, so it can also give lateral (turn left/right) instructions. It is however incompatible with TCAS.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-08-28T05:52:41.803" LastActivityDate="2014-08-28T05:52:41.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1890" PostTypeId="2" ParentId="1878" CreationDate="2014-02-24T04:53:01.510" Score="12" Body="&lt;p&gt;Yes, the strong magnetic fields which are created can cause all of those problems if it gets bad enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote the AIM where they talk about Precipitation Static (which is one method of creating St. Elmo's Fire):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0705.html&quot;&gt;&lt;strong&gt;AIM 7-5-11. Precipitation Static&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. A review of pilot reports often shows different symptoms with each&#xA;  problem that is encountered. The following list of problems is a&#xA;  summary of many pilot reports from many different aircraft. Each&#xA;  problem was caused by P-static:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. Complete loss of VHF communications.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. Erroneous magnetic compass readings (30 percent in error).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;3. High pitched squeal on audio.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;4. Motor boat sound on audio.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5. Loss of all avionics in clouds.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6. VLF navigation system inoperative most of the time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;7. Erratic instrument readouts.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;8. Weak transmissions and poor receptivity of radios.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;9. &quot;St. Elmo's Fire&quot; on windshield.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Each of these symptoms is caused by one general problem on the&#xA;  airframe. This problem is the inability of the accumulated charge to&#xA;  flow easily to the wing tips and tail of the airframe, and properly&#xA;  discharge to the airstream.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-24T04:53:01.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1891" PostTypeId="2" ParentId="1855" CreationDate="2014-02-24T08:55:21.063" Score="12" Body="&lt;p&gt;On the 747-100 and -200 airplanes we had windshield wipers which we occasionally used on short final in heavy rain. The switches were on the overhead panel on the captain's side, but the usual procedure was to ask the flight engineer to turn them on but to stand by to turn them off if the visibility was worse with them on than off, which was sometimes the case. I only remember leaving them on for the touchdown a couple of times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We never used them while taxiing that I recall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They were very noisy, distractingly so.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-24T08:55:21.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1892" PostTypeId="2" ParentId="1858" CreationDate="2014-02-24T09:24:42.897" Score="3" Body="&lt;p&gt;To give an example of the weight vs altitude capability for an old airplane, a 747-200 taking off at max weight isn't going to be able to climb higher than FL290 or FL310, and they may stagger to get to the latter. If the flight is in the neighborhood of 12 hours (which generally means a passenger aircraft as opposed to a freighter) FL390 or FL410 become usable. The aircraft is capable of FL450 if unusually light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though our old flight plans gave us the points that we could expect to be able to climb, there was a rule of thumb (which I unfortunately have forgotten) using the EPR that we used that quickly told us how many thousand feet above our current altitude we could get to.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-24T09:24:42.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1893" PostTypeId="1" AcceptedAnswerId="1896" CreationDate="2014-02-24T12:55:35.180" Score="19" ViewCount="13674" Body="&lt;p&gt;In general, passengers dislike turbulence. Avoiding all turbulence sometimes is not viable, as it would make the flight too long, too expensive (fuel consumed), or simply not having alternatives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the pilot deal with turbulence? Does he or she keep the same altitude? The same speed (relative to the wind)? Increase power?  AoA? &lt;/p&gt;&#xA;" OwnerUserId="616" LastEditorUserId="167" LastEditDate="2014-02-24T13:27:36.967" LastActivityDate="2014-02-25T15:07:02.150" Title="How does a commercial flight pilot handle turbulence?" Tags="&lt;pilot-technique&gt;&lt;turbulence&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1895" PostTypeId="2" ParentId="1893" CreationDate="2014-02-24T13:48:19.773" Score="4" Body="&lt;p&gt;The pilot can slow down the plane, or he can try flying at a different altitude. He also has the option of flying around it, although many times this is impractical.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-02-24T13:48:19.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1896" PostTypeId="2" ParentId="1893" CreationDate="2014-02-24T14:46:01.700" Score="27" Body="&lt;p&gt;Most of the time the turbulence we experience is termed &quot;chop&quot;, which is akin to what you experience on a boat on the lake -- bumps but no real altitude deviations.  With altitude deviations we'll call it &quot;turbulence&quot;.  Within these broad categories we'll qualify them with &quot;light&quot;, &quot;moderate&quot;, &quot;severe&quot; and &quot;extreme&quot; in reports to ATC and other aircraft.  These reports do suffer from a fair bit of subjectivity with respect to aircraft type (wing stiffness) and pilot experience.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is light chop, I'll generally just ride it out and turn the seatbelt signs on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing I'll do if encountering moderate chop or turbulence is to query ATC and get ride reports from aircraft ahead of us and at different altitudes than us.  From this information I'll make a determination to ride it out or to request a climb/descent.  If the turbulence was particularly bad, slowing down was an option, but I only came across that need a few times.  Our ability to descend would often be limited by route length and fuel and major lateral deviations also depended on contingency fuel, so in some cases we had no choice but to stay in the chop.  If the turbulent areas were well forecast or had lots of PIREPS, our dispatchers would sometimes route us differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for power adjustments, if we weren't slowing down due to aircraft limitations I would just adjust power so that maximum airspeed deviations stayed below Mmo. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-24T14:46:01.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1897" PostTypeId="1" AcceptedAnswerId="1899" CreationDate="2014-02-24T18:05:55.110" Score="9" ViewCount="2502" Body="&lt;p&gt;Is it possible for airline pilots to communicate with dispatchers? If so, what methods do they use? A special radio channel?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="258" LastEditDate="2014-02-24T18:44:46.160" LastActivityDate="2014-02-24T20:41:13.310" Title="Can airline pilots communicate with dispatchers?" Tags="&lt;radio-communications&gt;&lt;airline-operations&gt;&lt;dispatch&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1898" PostTypeId="1" AcceptedAnswerId="1931" CreationDate="2014-02-24T18:21:38.603" Score="37" ViewCount="14771" Body="&lt;p&gt;Considering that building runways is expensive and that they take up a lot of space, could you land a large commercial airliner on a circular runway, braking as you go around the curves?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="97" LastEditDate="2014-02-25T13:50:56.273" LastActivityDate="2020-02-21T14:26:53.303" Title="Could you land a large airplane on short circular runways?" Tags="&lt;landing&gt;&lt;runways&gt;" AnswerCount="11" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1899" PostTypeId="2" ParentId="1897" CreationDate="2014-02-24T18:42:13.417" Score="5" Body="&lt;p&gt;Yes, and it is a regulatory requirement that it is so.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§121.99   Communications facilities—domestic and flag operations.&lt;/p&gt;&#xA;&lt;p&gt;(a) Each certificate holder conducting domestic or flag operations must show that a two-way communication system, or other means of communication approved by the FAA certificate holding district office, is available over the entire route. The communications may be direct links or via an approved communication link that will provide reliable and rapid communications under normal operating conditions between each airplane and the appropriate dispatch office, and between each airplane and the appropriate air traffic control unit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The typical way to contact dispatch is through &lt;a href=&quot;http://en.wikipedia.org/wiki/SELCAL&quot; rel=&quot;noreferrer&quot;&gt;SELCAL&lt;/a&gt; which allows two way communications between two specific parties over HF or VHF radio.  To contact a dispatcher we would tune the COM associated with SELCAL to the proper frequency (these were charted on company airport pages and you would use one from an airport nearby that you are overflying) and then use our handheld microphone (with keypad) to dial a code for our dispatcher, which is noted on our release paperwork.&lt;/p&gt;&#xA;&lt;p&gt;As long as you are monitoring a SELCAL frequency and dispatch (or someone else with your aircraft code) calls you, the airplane will announce &amp;quot;SELCAL&amp;quot; and typically a light or some other visual notification will come on.&lt;/p&gt;&#xA;&lt;p&gt;Once connected, you talk to your dispatcher over that com radio the same as you would talk to ATC.  From there your dispatcher can connect you to maintenance, med link, or anyone else you might need to talk to.&lt;/p&gt;&#xA;&lt;p&gt;For larger airplanes typically used on overwater routes you will probably also find a satellite phone in the cockpit that can be used as an alternative way to call dispatch.&lt;/p&gt;&#xA;&lt;p&gt;Textual communications to and from dispatch are also possible using &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;noreferrer&quot;&gt;ACARS&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-24T20:41:13.310" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1900" PostTypeId="2" ParentId="1898" CreationDate="2014-02-24T18:44:14.533" Score="10" Body="&lt;p&gt;A circular runway maybe works but this circle can't be small as the turn must be really smooth, talking about just a few degrees per 1000 feet. So this runway would actually be very &quot;long&quot; and need a lot of space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's stop thinking about that! You would probably not be able to maintain 'directional' control if the outboard engine fails (e.g. left turning runway, right engine fails). How would you set up an ILS approach? Aircraft aren't build for this. It would be dangerous or even impossible and would never be approved.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="64" LastEditDate="2014-02-25T03:16:45.047" LastActivityDate="2014-02-25T03:16:45.047" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1901" PostTypeId="2" ParentId="1898" CreationDate="2014-02-24T19:17:05.600" Score="5" Body="&lt;p&gt;The cost of building a &quot;circular runway&quot; (probably with banked sides like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Velodrome&quot;&gt;Velodrome&lt;/a&gt;)  would probably be more difficult and expensive to build than a big long flat bit of concrete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to solve the same problem would be to use &lt;a href=&quot;http://en.wikipedia.org/wiki/Arresting_gear&quot;&gt;arresting gear&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_catapult&quot;&gt;catapults&lt;/a&gt; like they do on aircraft carriers (which have the same problem - too expensive to build a big enough runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd pay extra to land and take off on such a runway, but I may be in the minority :-)&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-02-24T19:17:05.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1902" PostTypeId="2" ParentId="1898" CreationDate="2014-02-24T22:12:31.527" Score="26" Body="&lt;p&gt;One major complication would be the shift in relative wind as you work your way around this curved runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On approach, the wind would be coming from one direction (ideally straight head), then as you touch down and begin your curve while slowing down, the wind shifts direction to come more from one side.  So now you're trying to stay on a centerline that is curving, at somewhat high speed, while the wind moves to one side of your plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is just insane.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Another major issue would be the amount of &quot;float&quot;.   Although airplanes target touching down right at the end of the runway, that doesn't always happen.  Sometimes due to excess speed, gusty winds, or a misjudged flare, the plane will float a distance down the runway before actually touching down.   During this time, the plane's nose may be high, and visibility of the runway is limited.  Because the runway is straight, it's no problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But suggesting that a pilot navigate a curved runway while floating further than anticipated is just nuts.  If they don't turn enough, they end up outside the curve of the runway.  If they turn too much, they end up inside the curve.  Either way, if they overcorrect at low altitude and airspeed, the chance of a catastrophic crash is unacceptably high.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="753" LastEditDate="2017-11-26T12:09:49.760" LastActivityDate="2017-11-26T12:09:49.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1903" PostTypeId="2" ParentId="1893" CreationDate="2014-02-24T22:30:32.557" Score="13" Body="&lt;p&gt;Some large aircraft (maybe all?) have a minimum and maximum turbulence penetration speed. For the 747-100 and -200 aircraft the minimum was 270 knots and the maximum 320 knots IAS. I forget the mach equivalents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those same aircraft had a turbulence mode on the autopilot that reduced the sensitivity to pitch and roll deviations. However, many pilots (including myself) would hand fly through heavy turbulence because the autopilot ride even in turbulence mode was worse than what we could get by hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are situations in which changing altitude is not an option. For example, if you cannot descend because doing so would burn too much fuel, but you cannot climb because you are already as high as you can go. It also may not be possible to deviate much from your course because of fuel considerations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a Hajj flight from Jakarta to Jeddah. It's 10 hours and that's what you've got fuel for. Depending on the time of day, there is often (seemingly always) a line of thunderstorms too long to go around between Sumatra and India. You pick your way through the line using radar to avoid the intense echoes.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-02-24T22:30:32.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1904" PostTypeId="1" AcceptedAnswerId="1905" CreationDate="2014-02-24T23:13:08.243" Score="25" ViewCount="7271" Body="&lt;p&gt;When moving to and from the runway, does a large passenger aircraft turn by changing the thrust difference on its side engines, or by turning the front landing gear to a different angle? If it is by turning the front landing gear, through what device does the pilot control the angle?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="97" LastEditDate="2014-04-28T00:00:51.830" LastActivityDate="2014-04-28T00:00:51.830" Title="Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?" Tags="&lt;landing-gear&gt;&lt;taxiing&gt;&lt;throttle&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1905" PostTypeId="2" ParentId="1904" CreationDate="2014-02-24T23:17:02.507" Score="27" Body="&lt;p&gt;During taxiing aircraft turn using their nose wheel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose wheel is usually hydraulically controlled. The pilot operates it through a tiller. The nose gear can rotate usually quite far, sometimes to almost 90 degrees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high speeds, directional control is achieved using the rudder pedals. The nose gear is often linked to the rudder pedals, however the maximum rotation is limited. The nose gear steering does not exactly match to the the rudder steering at all speeds. At low speeds the rudder is ineffective so the nose wheel steering is dominant. For sharp turns the tiller is always used because of the limited rotation by the pedals.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UxP7a.jpg&quot; alt=&quot;A320 Nose wheel tiller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A320 Nose wheel tiller&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AOuAS.jpg&quot; alt=&quot;B747-400 Nose wheel tiller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B747-400 Nose wheel tiller&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-02-27T13:44:45.453" LastActivityDate="2014-02-27T13:44:45.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1906" PostTypeId="1" AcceptedAnswerId="1907" CreationDate="2014-02-24T23:39:37.323" Score="11" ViewCount="3401" Body="&lt;p&gt;Considering that airplanes are very noisy, could one routinely land them with the engines turned off, gliding onto the runway? Could the engines be started fast enough for an emergency situation?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2016-12-27T09:47:08.033" Title="Is landing without engine power routinely feasible?" Tags="&lt;landing&gt;&lt;noise&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1907" PostTypeId="2" ParentId="1906" CreationDate="2014-02-25T00:37:57.457" Score="27" Body="&lt;p&gt;Not feasible. A start of each engine can take 30-60 seconds or longer and would require the APU (noisy). In some airplanes you lose the packs during start so you would impact pressurization. Additionally many engines have a required time at idle after start before significant thrust is applied.  Lastly, with all engines offline, the airplane will be in some sort of essential power mode and many systems will be offline or unavailable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might then ask that we land at idle but that can present issues with spool up time before thrust is available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the primary reason we land with a high flap setting is so that we have the drag to maintain approach speeds with the engines spooled up. This gives us near immediate power if we need it to go around. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure someone else can provide historical data from when idle approaches in jets were normal and specifics into why we don't do this today. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-25T00:48:36.363" LastActivityDate="2014-02-25T00:48:36.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1908" PostTypeId="2" ParentId="1906" CreationDate="2014-02-25T00:48:00.753" Score="18" Body="&lt;p&gt;Is it &lt;em&gt;possible&lt;/em&gt; to land them with the engines off routinely?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;. Depending on the glide ratio of the aircraft, you most certainly &lt;em&gt;can&lt;/em&gt; land them. And in flight training, we do practice this routinely, although we don't actually turn the engine off for safety reasons, merely reducing the power to idle. Technically, this is not the same thing, as the propeller is still turning and producing thrust, and of course the engine is on, producing noise, but it is certainly good to know &lt;em&gt;how&lt;/em&gt; to land without an engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I suspect you really were asking about the more important part of the question - &lt;em&gt;should&lt;/em&gt; you, and is it safe?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, &lt;strong&gt;no, not really&lt;/strong&gt;. You can check out &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding&quot;&gt;this list&lt;/a&gt; of flights that required gliding. You'll notice that several incidents that required gliding were very succesful, and they glided for quite a long way. However, most notably for your question is the first flight on the list - a DC-3 on approach lost its engines and attempted to glide in. They failed to clear a mountain, and crashed, killing everyone aboard. If you were gliding into an airport, and suddenly needed power, it would take too long to restart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, if weather conditions caused your first approach to be off, it would be definitely better to 'go around' than attempt to save a bad landing. Just watch the first landing of &lt;a href=&quot;http://www.youtube.com/watch?v=fJSDaVVAc1c&quot;&gt;this video&lt;/a&gt;. It would not be possible to restart and engine before touchdown in that situation. &lt;em&gt;Maybe&lt;/em&gt; it could be done earlier in the approach, but as the landing is a task-saturated phase of flight, you do not want to attempt it in those situations (in my training, we do not attempt to restart an engine under 2,000' AGL).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in summary, yes it could be done, but no, you absolutely wouldn't want to do it because of the potential for needing instant power.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-08-03T20:10:55.713" LastActivityDate="2014-08-03T20:10:55.713" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1909" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T02:04:08.250" Score="28" Body="&lt;p&gt;As a matter of physics, there's a certain amount of braking and steering force available to the aircraft after it lands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose the aircraft touches down moving due north, and continues clockwise around your circular runway. After a quarter-circle it travels due east -- but that means that enough braking force has been applied to reduce the northward component of its velocity to zero, while also giving it some eastward velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If only that eastward force &lt;em&gt;hadn't&lt;/em&gt; been applied, the aircraft would be at a halt now -- using &lt;em&gt;less&lt;/em&gt; force than what's necessary for it to follow the circle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the plane can keep itself on a circular runway, it will be even easier for it to come to a halt on a &lt;em&gt;straight&lt;/em&gt; runway whose length is the &lt;em&gt;radius&lt;/em&gt; of the circle.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;(Also, the plan ignores that the critical factor in the length of runways is not landing but taking off -- there must be enough runway to brake down safely if the takeoff is aborted just before rotation. And &lt;em&gt;taking off&lt;/em&gt; from a curved runway sounds even crazier than landing. If the runway is horizontal, the plane would become airborne in the middle of an uncoordinated turn...)&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-02-25T02:04:08.250" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="1910" PostTypeId="1" AcceptedAnswerId="1943" CreationDate="2014-02-25T03:44:07.753" Score="8" ViewCount="33380" Body="&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/281/takeoff-and-landing-in-zero-visibility&quot;&gt;previous question&lt;/a&gt; pondered the legality and safety of low visibility Part 91 takeoffs. I am wondering about the requirements for low visibility takeoff for commercial airline operators (e.g. Part-121 scheduled operations). I know of authorizations for operators down to 600 RVR (though I believe I recall 300 RVR for one carrier out of DEN), and various requirements for other increments below standard takeoff minima.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Which RVR are authorized and what ground equipment requirements need to be met to use them?&lt;/li&gt;&#xA;&lt;li&gt;What authorizes (regulation? op spec?) these reduced visibility operations? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2018-04-03T11:14:48.187" Title="Who authorizes low visibility takeoff operations for airlines, and what is required?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;takeoff&gt;&lt;far-121&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1911" PostTypeId="1" AcceptedAnswerId="1922" CreationDate="2014-02-25T04:00:05.167" Score="14" ViewCount="2087" Body="&lt;p&gt;What effect will the time of year a student starts their flight training have on the difficulty of their training?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What particular problems will each season cause a student pilot? &lt;/li&gt;&#xA;&lt;li&gt;What advantages does each season have? &lt;/li&gt;&#xA;&lt;li&gt;Are there any studies showing how the time of year effects the duration or success rate of training? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Different latitudes will have different, or at least more extreme, effects so please note if an effect is only valid for a specific geographic area. &lt;/p&gt;&#xA;" OwnerUserId="51" LastEditorUserId="19" LastEditDate="2017-01-16T13:45:12.883" LastActivityDate="2017-01-16T13:45:12.883" Title="What are the effects of different seasons on flight training?" Tags="&lt;flight-training&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1912" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T04:09:57.873" Score="3" Body="&lt;p&gt;As many of these other answers speak to as well, the rate of turn for aircraft on the ground is very low, so the circle would have to be far larger than practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, on a very related note, early airports all had circle landing areas. From wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The earliest aircraft takeoff and landing sites were grassy fields. The plane could approach at any angle that provided a favorable wind direction. A slight improvement was the dirt-only field, which eliminated the drag from grass. However, these only functioned well in dry conditions. Later, concrete surfaces would allow landings, rain or shine, day or night.&#xA;  &lt;a href=&quot;http://en.wikipedia.org/wiki/Airport&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Airport&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="963" LastActivityDate="2014-02-25T04:09:57.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1913" PostTypeId="1" AcceptedAnswerId="3666" CreationDate="2014-02-25T08:39:39.100" Score="15" ViewCount="2124" Body="&lt;p&gt;There are &lt;a href=&quot;http://www.nasa.gov/centers/ames/multimedia/images/2005/nfac.html&quot; rel=&quot;noreferrer&quot;&gt;very large wind tunnels&lt;/a&gt; out there. Wouldn't it be very efficient to test new airplanes flying them &quot;on the spot&quot; inside of these tunnels? That is, in free flight - not mounted to a pylon? One could presumably omit the test pilot and remote control them, get excellent visual feedback and have a completely controlled environment. Has this been done? If not, why?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="1696" LastEditDate="2015-06-05T20:14:54.843" LastActivityDate="2015-06-05T20:14:54.843" Title="Can you fly a plane in a wind tunnel?" Tags="&lt;aircraft-certification&gt;&lt;wind-tunnel&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1914" PostTypeId="1" AcceptedAnswerId="1927" CreationDate="2014-02-25T09:08:29.603" Score="24" ViewCount="10064" Body="&lt;p&gt;You pull a flap on airplane seatbelts, you push a button on car seatbelts. Why?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2018-11-28T15:10:33.473" Title="Why is the seat belt mechanism on airplanes so different from the the one on cars?" Tags="&lt;safety&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1915" PostTypeId="2" ParentId="1913" CreationDate="2014-02-25T11:56:59.210" Score="10" Body="&lt;p&gt;Could you? Yes, probably, but it would be very difficult due to the very limited space. You would have to have a huge airflow in excess of 50 knots for a small aircraft, and you could not simulate any motion fully, such as takeoffs rolls. You could also not test stalls and other manoeuvres. I think the main reason against this is that this is simple areas of flight dynamics that can just as well be done with computational fluid dynamics on a computer for a fraction of the effort and cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think it would be safer either. It's a very confined space, and you couldn't cut the airflow very quickly, so it's probably more dangerous than flying outside with unlimited space and a stable airflow.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-25T12:03:13.960" LastActivityDate="2014-02-25T12:03:13.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1916" PostTypeId="2" ParentId="1914" CreationDate="2014-02-25T12:01:09.043" Score="6" Body="&lt;p&gt;I think the classic economy class buckle is just a compromise: On cars, you can easily reach the side of the seat, and it's more comfortable to have it on the side than a block of metal in the middle. In aircraft seats however, it's difficult to reach down in between, and if something happens quickly, you want to easily release it. The design itself might have a historical element, since a seatbelt which is very easy to open might make passengers feel safer, especially when many were new to flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, there are several business-class seats today which utilize conventional seatbelt styles.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-02-25T14:19:11.973" LastActivityDate="2014-02-25T14:19:11.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1917" PostTypeId="1" AcceptedAnswerId="7518" CreationDate="2014-02-25T12:15:13.340" Score="39" ViewCount="62615" Body="&lt;p&gt;Large passenger planes almost always have their engines hanging from the wings, Fighters usually have them in the rear, and small Cessnas have them on the nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for these variations in design?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="64" LastEditDate="2014-02-27T21:59:14.907" LastActivityDate="2016-09-25T02:34:15.957" Title="Why do large aircraft have their engines mostly on the wings, while smaller ones tend to have them in the tail or the tip?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1918" PostTypeId="2" ParentId="1913" CreationDate="2014-02-25T12:21:48.717" Score="3" Body="&lt;p&gt;No, you cannot fly a plane like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Problem is: propulsion is missing. Once you expose a plane model to an airstream, the airfoils (wings) start producing lift but also drag. In real world, an airplane requires propulsion to overcome the drag (induced drag,parasite drag,..) in order to move forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wind tunnel airplane model would just lift-off and fall behind, there would be no chance to establish a stabilized flight attitude where propulsion equals drag and lift equals weight. Such a stabilization is required to seriously start measuring. That's why the models are strapped down to a pylon or whatever. Measuring results can therefore also be reproduced (certain fixed AoA's at certain airstream speeds etc.)&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2014-02-25T12:21:48.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1919" PostTypeId="2" ParentId="1917" CreationDate="2014-02-25T12:45:59.103" Score="6" Body="&lt;p&gt;Mostly because of the number of engines. If you have more than one engine then it gets hard to put both in the middle. It can be done, there are fighters with two engines in the middle, but it makes more sense (less noise, easier maintenance, etc) to put them in the wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also a weight advantage. The wings lift the plane, the engines are a major weight component of the aircraft. So if the weight is where the lift is being produced you don't need to reinforce the structure to carry the forces around. Hence lighter structure. &lt;/p&gt;&#xA;" OwnerUserId="970" LastActivityDate="2014-02-25T12:45:59.103" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1920" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T12:59:27.403" Score="-5" Body="&lt;p&gt;Different point of views can be derived of such a suggestion:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Huge turntable-like runways which turn while the landing aircraft rolls out. Turning at the same speed as the aircraft decelerates, result in the aircraft always be facing the same wind conditions during stopping process.&lt;/li&gt;&#xA;&lt;li&gt;Development of the first item: a treadmill-like landing runway. At the time of touchdown the aircraft does not require any airstream along its wings. The following deceleration could be performed on a treadmill or assembly line.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But honestly, none of them would financially or even technically pay off the effort of just expanding existing runways in length.&lt;/p&gt;&#xA;" OwnerUserId="968" LastEditorUserId="64" LastEditDate="2014-02-26T16:22:28.350" LastActivityDate="2014-02-26T16:22:28.350" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1921" PostTypeId="2" ParentId="1917" CreationDate="2014-02-25T13:06:02.947" Score="8" Body="&lt;p&gt;Also the nose-up moment during acceleration and likewise nose-down moment during deceleration with an under-wing engine design are favourable for stable flight characteristics. (the center of gravity is located in front of the center of pressure)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes with tail engines behave the other way around: during acceleration they produce a nose-down moment around their lateral axis. This in turn causes more drag and eventually more money. During deceleration, the nose-up moment can be dangerous, considering a near stall situation or slow flight in general.&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2014-02-25T13:06:02.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1922" PostTypeId="2" ParentId="1911" CreationDate="2014-02-25T13:45:07.110" Score="9" Body="&lt;p&gt;Pretty much the only thing that is going to change season to season is the weather. Depending on &lt;em&gt;where&lt;/em&gt; you are, there may be more aircraft traffic around a particular time of year, but I can't answer that for sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the further from the equator, the more extreme the seasons. If you are close to the equator, it probably doesn't matter what time of year you start, since the weather is pretty much the same year-round.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are not at the equator, you need to consider the pros and cons of each weather season. Additionally, at extremes from the equator (near the poles), summer and winter months have extremely long days and long nights, respectively, which can make night and day flying difficult.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In the winter, the aircraft has better performance (airplanes like colder weather). &lt;em&gt;However&lt;/em&gt;:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You have to deal with ice and snow, which is especially dangerous to light airplanes, which are often not as prepared to deal with them. It is dangerous in some degree to &lt;em&gt;all&lt;/em&gt; airplanes&lt;/li&gt;&#xA;&lt;li&gt;You have to be careful of low temperatures when starting the airplane before you take off&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In the summer, the aircraft has worse performance (they don't like hot weather).&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Many small airplanes have poor airflow &lt;em&gt;inside&lt;/em&gt; the cockpit, which means they can get rather hot (it is easier to run a heater inside a small cockpit than cool it)&lt;/li&gt;&#xA;&lt;li&gt;You have to be more careful to avoid overheating the engine&lt;/li&gt;&#xA;&lt;li&gt;Some places may form thunderstorms constantly&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In the rainy season, which is often in the spring, you will have degraded performance. Even if it is not rainy, the air will likely be more humid, which decreases aircraft performance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Depending on your latitude, other weather conditions may be more prevelant at a certain time of year (hurricanes/cyclones, high winds, tornados, sudden storms). &lt;a href=&quot;http://topex.ucsd.edu/sandwell/publications/9.pdf&quot; rel=&quot;nofollow&quot;&gt;This paper&lt;/a&gt; discusses wind differences based on season and latitude. In particular, page 7 of the document shows that summer months had slightly stronger winds at southern latitudes (southern hemisphere), and winter months had significantly stronger winds at northern latitudes. Some geographical areas may have changes in &lt;em&gt;prevailing wind directions&lt;/em&gt;, which could also affect training depending on routes and runways too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;: It's mainly a weather concern, which can affect your comfort (temperature inside, possibly air turbulence), aircraft performance, as well as grounding weather. Additionally, the most obvious concern is also length of the day - summer months will have more daylight, a particular concern if you can only fly in VFR conditions/do not hold a night rating.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-02-26T20:17:28.323" LastActivityDate="2014-02-26T20:17:28.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1925" PostTypeId="1" CreationDate="2014-02-25T15:26:40.213" Score="5" ViewCount="1603" Body="&lt;p&gt;After purchasing an aircraft, it takes the FAA a long time to issue RVSM approval for the new owner.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this time, under what conditions may an aircraft fly in RVSM airspace even though they aren't approved for it?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the process to get ATC approval for such flights?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2018-02-21T21:53:29.433" Title="Under what conditions can a non-RVSM aircraft or pilot fly in RVSM airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;rvsm&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1926" PostTypeId="1" CreationDate="2014-02-25T15:43:03.117" Score="4" ViewCount="903" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1787/which-airplanes-are-exempt-from-europes-2015-cpdlc-link-2000-requirement&quot;&gt;Another question&lt;/a&gt; lists the aircraft that are exempt from the EASA CPDLC rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a similar exemption for aircraft operating in the North Atlantic?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-12-15T21:02:37.150" Title="Are there aircraft exemptions for CPDLC in the NAT area?" Tags="&lt;avionics&gt;&lt;cpdlc&gt;&lt;nat&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1927" PostTypeId="2" ParentId="1914" CreationDate="2014-02-25T18:16:59.030" Score="19" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/1914/why-is-the-seat-belt-mechanism-on-airplanes-so-different-from-the-the-one-on-car#comment3383_1914&quot;&gt;Roe pointed out&lt;/a&gt; you don't necessarily pull a flap on airplane seatbelts -- Sometimes (particularly in newer light GA planes from the 1990s and on) you push a button just like you do in a car, other times it's the &quot;utility buckle&quot; (flap buckle) - sometimes with a shoulder harness attach peg or other attach mechanism, and sometimes you'll find rotary buckles, where you turn a knob to release the belt (particularly common in aerobatic aircraft, with 4-point or 5-point restraints).  I've attached a little gallery of belt types below (and this isn't even complete - military aircraft hafe some &lt;em&gt;downright funky&lt;/em&gt; buckles!).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/FqPx0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FqPx0s.jpg&quot; alt=&quot;Push-Button (&amp;quot;automotive-style&amp;quot;) belts, Piper Warrior III&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/V2GoP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V2GoPs.jpg&quot; alt=&quot;Flap buckle w/ shoulder harness - Alpha Aviation&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/9SR1l.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9SR1ls.jpg&quot; alt=&quot;Flap buckle with 2 shoulder harness attachments&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/NyeQQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NyeQQs.jpg&quot; alt=&quot;rotary buckle&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;This variety is why the FAA requires flight crew to instruct passengers in the operation of the seat belts.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, why are the belts in airplanes different?  And why are there so many types?&lt;br&gt;&#xA;Each belt is good at something different, and each belt has its own set of drawbacks.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The automotive style push-button belt is very familiar to infrequent flyers.&lt;/strong&gt;&lt;br&gt;&#xA;Most people who are going to get on a plane have been in a car (they probably rode in one to the airport), so familiarity with automotive-style seatbelts can generally be assumed. This is great when you take someone for a flight who isn't a frequent airline passenger.&lt;br&gt;&#xA;The drawback to the automotive belt is it's not as easy for rescuers to operate, and the push-button mechanism can jam - particularly in fires where the plastic shell can melt/fuse (in cars the belts are often cut by rescuers because it's easier/faster than dealing with the button). If your passengers are injured in an emergency and can't operate the belt it may be difficult for you to locate and press the button to assist in evacuation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The &quot;utility buckle&quot; flap belt is easy for rescuers &amp;amp; cabin crew to operate.&lt;/strong&gt;&lt;br&gt;&#xA;The exact opposite of the push-button belt's chief drawback: It's really easy for cabin crew or rescurers to find a utility buckle on a belt by feel and yank the flap to release it (try it some time: Buckle someone into an airplane seat, close your eyes, and find/release the buckle. The hardest part is finding the &lt;em&gt;belt&lt;/em&gt; if they're wearing bulky clothes). It's also relatively hard to jam a utility buckle, and relatively easy to inspect them to determine if they're damaged.&lt;br&gt;&#xA;The drawback to the utility buckle is that not everyone has been on an airplane (or in a &lt;em&gt;really old car&lt;/em&gt; that uses them), so they might not be familiar with &quot;Lift the flap to release the belt&quot;, and in a panic situation it may take them a few seconds to remember what to do.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The rotary buckle is unique and kind of awesome for what it's built for.&lt;/strong&gt;&lt;br&gt;&#xA;Rotary buckles make it easy to attach 4 or 5 point restraints, and to release all or part of them quickly.  (The buckle shown in the photos is single-function - turn to release - but dual-function buckles exist where you can press the button in the center of the buckle to release the shoulder straps, or turn the knob to release everything.)&lt;br&gt;&#xA;The big drawbacks to rotary buckles are their novelty: On the ground you usually only find them on 5-point racing harnesses, and in the air they're pretty uncommon too (mainly aerobatic aircraft as I mentioned earlier). They're probably the last type of buckle a passenger or rescuer would expect to have to deal with, and particularly with the dual-action buttons they can present a challenge in a panic egress (passengers will hit the button and release the shoulder harnesses, but they're still restrained by the lower portion of the belt - this can cost precious time for them to realize they have to turn the knob).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-02-25T18:16:59.030" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="1928" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T18:34:43.737" Score="-6" Body="&lt;p&gt;This will work if the circular runway is rotating.&#xA;The runway should be on a pedestal, and spin up to an to an angular velocity such that the tangent matches the aircrafts speed.  then rise up and catch the aircraft, slowly reducing angular velocity and lowering to the tarmac.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take off would proceed in the reverse manner.  with the aircraft speeding up trying to stay on the rotating runway as it rises and increases angular velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of alien invasion we can use the rotating run ways to launch projectiles such as the airport busses.&lt;/p&gt;&#xA;" OwnerUserId="979" LastActivityDate="2014-02-25T18:34:43.737" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1929" PostTypeId="2" ParentId="1913" CreationDate="2014-02-25T18:44:51.570" Score="6" Body="&lt;p&gt;You certainly &lt;a href=&quot;https://aviation.stackexchange.com/a/1915/64&quot;&gt;&lt;em&gt;could&lt;/em&gt;&lt;/a&gt; fly a completely assembled aircraft in a sufficiently-large wind tunnel -- at least in &lt;em&gt;theory&lt;/em&gt; (theory is an awesome place - everything always works there. When I retire I'm moving to theory).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality there are lots of drawbacks which have already been pointed out, but there's one that hasn't been yet: Wind tunnel testing is traditionally done with scale models, and even then it's not &quot;cheap&quot;: It takes a lot of power to move wind through a tunnel at high speed, and scaling this up to a full size airframe - even small-airplane size like your typical Cessna or Piper trainer - is cost-prohibitive since you would have to build the entire plane and then pay to blow high-velocity air over it.&lt;br&gt;&#xA;(&lt;a href=&quot;http://en.wikipedia.org/wiki/Ames_Research_Center#National_Full-Scale_Aerodynamics_Complex_.28NFAC.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;There &lt;em&gt;are&lt;/em&gt; wind tunnels at this scale&lt;/a&gt; though - at least one. NASA spent a lot of money on it, and then Boeing and Airbus came out with their new super-jumbo planes which don't fit!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth pointing out that the kind of fluid dynamics modeling that used to be done with wind tunnels and smoke trails is now often done with &lt;a href=&quot;http://en.wikipedia.org/wiki/Computational_fluid_dynamics&quot; rel=&quot;nofollow noreferrer&quot;&gt;Computational Fluid Dynamics (CFD) software&lt;/a&gt;. Cheaper, Safer (no risk of parts blowing off and bouncing down the tunnel), and more accurate in many regards -- but nowhere near as much fun to watch :)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-02-25T18:44:51.570" CommentCount="0" CommunityOwnedDate="2014-02-25T18:44:51.570" ContentLicense="CC BY-SA 3.0" />
  <row Id="1930" PostTypeId="2" ParentId="1844" CreationDate="2014-02-25T19:21:03.810" Score="8" Body="&lt;p&gt;OK, I sat on my hands for a while, so now I'll stick my head in the lion's mouth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You should absolutely sump your tanks &lt;em&gt;every time you go flying&lt;/em&gt;&lt;/strong&gt; as part of a routine preflight inspection, whether you've taken on fuel or not, whether the aircraft has been hangared or out on the ramp, and &lt;em&gt;even if it's below freezing&lt;/em&gt;.&lt;br&gt;&#xA;Water isn't the only thing you're looking for (misfueling happens - also bits of fuel tank sealant, rubber from a rotting bladder, dirt that made it past the fueling truck's filters, etc. - you want to find these things!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally if it's below freezing you should also pre-heat your aircraft so the &lt;a href=&quot;https://aviation.stackexchange.com/questions/347/when-is-pre-heating-a-piston-engine-important-and-how-does-one-pre-heat-correct&quot;&gt;engine&lt;/a&gt;, instruments, and &lt;strong&gt;&lt;em&gt;fuel&lt;/em&gt;&lt;/strong&gt; are above freezing when you're preflighting (which is generally accomplished by sticking the plane in a heated hangar), but sometimes that's not an option and you make do.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Why should you sump the tanks if it's below freezing?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Well like I said above, water isn't the only thing we're looking for - and all those concerns still hold valid no matter what the temperature is. Water is the one that people seem to come up with as a reason for not sumping when it's below freezing though, so let's talk about water:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are five general ways water can manifest itself in your (Avgas) fuel system:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Liquid Water&lt;/strong&gt;&lt;br&gt;&#xA;If it's not been below freezing (or it's really sunny and your fuel tanks have acted like an oven) water may be liquid, waiting for you at the sump drain just like on a warm summer day. You'll drain it out and go on about your business.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Slush&lt;/strong&gt; (ice crystals suspended in the fuel)&lt;br&gt;&#xA;If it's below freezing you may have suspended ice crystals or slush in the fuel (particularly if you just took on fuel). This will look &quot;cloudy&quot; when you drain it from the sump and it's a good indication that today is &lt;em&gt;not&lt;/em&gt; a good day to fly: you may have a LOT of water in the fuel, and you need to need to deal with it (warm the plane up and drain off the water, and figure out how so much of it got in there in the first place).&lt;br&gt;&#xA;(There is a chance that slush could jam your fuel drain open, in which case your fuel tank will empty itself onto the ramp with great rapidity.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Little bits of ice&lt;/strong&gt;&lt;br&gt;&#xA;Little drops of water can freeze into little bits of ice, which are often just too big to come out of the fuel sump drain, but just small enough to lodge in it and keep it from closing (which, again, will cause your tank to empty itself onto the ramp with great rapidity. This is also an indication that today is &lt;em&gt;not&lt;/em&gt; a good day to fly).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;BIG bits of ice over the sump drain&lt;/strong&gt;&lt;br&gt;&#xA;Liquid water will flow to the lowest point in the fuel system (the drains). If it's below freezing it will freeze there, potentially blocking the sump drain.&lt;br&gt;&#xA;You'll notice this condition because the sump valve may feel stiff, your tank may not drain, or it will drain very slowly, possibly with water in the fuel.&lt;br&gt;&#xA;This is a good indication that you shouldn't fly until you figure out what the cause of the problem is (it could be ice, it could be a defective valve, or it could be a bunch of other things, but until you know you want to stay on the ground).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Hidden Ice&lt;/strong&gt; (big bits of ice &lt;em&gt;away&lt;/em&gt; from the sump drain)&lt;br&gt;&#xA;This is perhaps the most insidious: Ice that's not near the sump, and doesn't block or jam anything.  Hopefully you'll spot this sitting at the bottom of your tank when you look in to check the fuel level (you do visually check your fuel level, &lt;em&gt;right&lt;/em&gt;?), but you probably won't notice anything out of the ordinary when you sump the tank.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;(There are of course &lt;em&gt;other&lt;/em&gt; ways water can hide out in the system besides the fuel tanks, but these are where you're most likely to find it.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most likely &quot;bad thing&quot; to happen to you in any of those scenarios is that your fuel sump will be jammed open by ice. This means you'll spill a tank's worth of avgas on the ground, and you'll have to call your airport's spill cleanup/emergency number and let them know.&lt;br&gt;&#xA;That emergency is on the ground, and it may be a little embarrassing to have to explain to the spill cleanup folks, but it's better than the other possibilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Bad Things that can happen to you in the air if you go flying with undetected ice/water in the fuel are far worse: The ice could melt and your engine could start trying to burn water, which doesn't ignite very well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://genebenson.com/why-2/player.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Check out Gene Benson's &quot;Why Did They Do That? - Volume 2&quot; presentation, starting at slide #7&lt;/a&gt; for one example of how things can go catastrophically wrong if you neglect to sump your tanks (or ignore the warning signs when you &lt;em&gt;do&lt;/em&gt;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-02-25T21:36:21.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1931" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T19:28:20.440" Score="21" Body="&lt;p&gt;Since there are actual projects for things like this I guess it is possible at least in principle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MDfzH.jpg&quot; alt=&quot;endless runway visualization&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.endlessrunway-project.eu/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.endlessrunway-project.eu/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the site: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The main feature of the circular runway is that it will become&#xA;  possible to let an aircraft operate always at landing and take-off&#xA;  with headwind. Whatever its strength and direction, the Endless Runway&#xA;  becomes independent of the wind. When allowing  limited crosswind,&#xA;  airspace users can shorten the global trajectory of the flights &#xA;  through optimized departure and arrival routes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apart from that they seem to hope that they can start/land more airplanes per time unit by shifting the start/landing point thus avoiding the problem that airplanes must not follow other airplanes to close along the same trajectory.&lt;/p&gt;&#xA;" OwnerUserId="980" LastEditorUserId="20149" LastEditDate="2020-02-20T10:46:18.300" LastActivityDate="2020-02-20T10:46:18.300" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="1932" PostTypeId="2" ParentId="1917" CreationDate="2014-02-25T21:10:41.153" Score="24" Body="&lt;p&gt;When designing an aircraft one basic factor is the thrust needed. In order to meet the requirements in power one or more engines are used. Factors that affect the selection are overall engine size, performance, efficiency, cost, material and thermal limitations during operation conditions like take-off, max continuous, max climb and max cruise. The installation has to be made with the lowest possible weight, drag and cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The positioning is indicated by aerodynamic factors such as drag, aircraft performance and manoeuvrability -pitching moments change around the center of gravity- and airflow through the engine, structural and purely functional/safety like debris injection inside the engine during landing or takeoff. All the above is just to give you a small taste of how the procedure goes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, selecting the correct engine or combination of engines and the optimal positioning is a quite complicated and sometimes very tedious process. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However simply put, the amount of thrust -taking into consideration the minimum and maximum required for certification, performance etc- is split among the engines. Now let's address each type of aircraft in your question individually and try to make the logic behind the positioning:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fighters&lt;/strong&gt;:&lt;br&gt;&#xA;These don't have the engines in the rear (e.g. they don't have pusher props), usually the jets are either underneath the fuselage &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot;&gt;like the Eurofighter Typhoon&lt;/a&gt;, incorporated to the fuselage, or the cockpit sits ontop of the jet nacelle &lt;a href=&quot;http://en.wikipedia.org/wiki/LTV_A-7_Corsair_II&quot;&gt;like the Corsair II&lt;/a&gt; while in all cases the output nozzle is at the rear. The reasoning behind this positioning is the need for power and high speed. Apart that the fuselage is the only place where the engines won't hinder the mounting of missiles and other ammunition on the wings where they can be placed, inspected and replaced on demand and with ease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Large passenger jets&lt;/strong&gt; (&lt;a href=&quot;http://commons.wikimedia.org/wiki/File%3aBa_b747-400_g-bnle_arp.jpg&quot;&gt;like the Boeing 747&lt;/a&gt;):&lt;br&gt;&#xA;The main characteristic of this type is that the space in the fuselage is needed for the passengers' accomodation. This alone rules out the incorporation of the engine in the fuselage as was the case in the fighters. The total weight increases leading to a need in power. The latter dictates either a very large single engine or more smaller ones -which is usually the case- that have to be distributed around the body which makes it logical to be put under the wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Medium/Small passenger jets&lt;/strong&gt; (like &lt;a href=&quot;http://pictures.topspeed.com/IMG/crop/201001/cessna-citation-must-4_600x0w.jpg&quot;&gt;the Cessna Citation Mustang&lt;/a&gt; or &lt;a href=&quot;http://www.aircharter.uk.com/images/aircraft/Executive_Heavy/Dassault_Falcon_900B_External_lrg.jpg&quot;&gt;Dassault Falcon 900&lt;/a&gt;):&lt;br&gt;&#xA;When the aircraft becomes smaller and the clearence of the wings from the ground becomes smaller the engines cannot be mounted under the wings without practical problems. So the engines move towards the tail where the fuselage needs to be reinforced to support the additional weight. The overall performance of the aircraft is different than that of a wing-mounted-engine aircraft because the cg is moved aft when it is empty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Small Cessnas and others&lt;/strong&gt; have a single engine in the nose because, as by now should be obvious, they need the power that can be provided by that single engine and for reasons of symmetry and construction costs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the above is a brief attempt to demonstrate the general thought process behind the positioning of the engines. Each way has it's pros and cons that every engineer takes into consideration and although these are the general configurations exceptions do exist. Some are &lt;a href=&quot;http://www.youtube.com/watch?v=SV96hXwWN7c&quot;&gt;this asymetric BV 141&lt;/a&gt;, or &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10&quot;&gt;this DC-10&lt;/a&gt; that has both wing and rear mounted engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further reading &lt;a href=&quot;http://adg.stanford.edu/aa241/propulsion/engineplacement.html&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="376" LastEditorUserId="64" LastEditDate="2014-02-27T22:07:27.783" LastActivityDate="2014-02-27T22:07:27.783" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1933" PostTypeId="2" ParentId="1913" CreationDate="2014-02-25T21:36:46.940" Score="12" Body="&lt;p&gt;It would actually miss the point of wind tunnel testing. A free flying model could only be subject to air stream in speed and direction so that the forces are balanced. A fixed model on the other hand can be subject to air stream of any direction and speed and the forces measured. It is important to measure the forces under those conditions too.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-02-25T21:36:46.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1934" PostTypeId="1" AcceptedAnswerId="1946" CreationDate="2014-02-25T22:26:17.850" Score="13" ViewCount="1022" Body="&lt;p&gt;I was flying a Fokker 100 a few months back over central Europe. We had probably just reached cruising altitude when the &lt;strong&gt;cabin temperature suddenly skyrocketed without reason&lt;/strong&gt;, with the air coming out probably around 30 degrees (Celsius). After complaints by fellow travellers it became cooler. Is there any reason why it would do this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess the pilots might have done it, but I see no reason for it, so could the aircraft have done it on its own accord?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="774" LastEditDate="2014-02-25T22:43:51.613" LastActivityDate="2015-11-02T07:30:41.683" Title="Is there any reason for why the cabin temperature would suddenly become very high?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1935" PostTypeId="1" AcceptedAnswerId="1939" CreationDate="2014-02-25T22:56:57.333" Score="15" ViewCount="2397" Body="&lt;p&gt;If an engine fails after $V_1$, how long does the copilot remain in control if he was the pilot flying? What is prioritized before the captain taking control of the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="3386" LastEditDate="2017-04-27T23:58:26.650" LastActivityDate="2017-04-27T23:58:26.650" Title="Does the co-pilot still remain in control of the plane if an engine fails during takeoff?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;commercial-operations&gt;&lt;crew-resource-management&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1937" PostTypeId="1" AcceptedAnswerId="1942" CreationDate="2014-02-25T23:46:29.590" Score="17" ViewCount="3057" Body="&lt;p&gt;I would assume that buzzing the tower and general hot dogging around the airport is prohibited, so how do airshow pilots get practice? Do they practice at high altitudes? If that is the case, how do they practice stunts that by nature require low altitude, like Bob Hoover's waltzing landing?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="69" LastEditDate="2014-02-26T13:13:24.450" LastActivityDate="2014-04-11T19:09:54.157" Title="Where do airshow pilots practice?" Tags="&lt;faa-regulations&gt;&lt;aerobatics&gt;&lt;airshow&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1938" PostTypeId="2" ParentId="1898" CreationDate="2014-02-25T23:52:14.493" Score="8" Body="&lt;p&gt;The problem with some of these proposed ideas (like a treadmill) is that they don't account for the inertia of the plane. You can't take a 500,000 lb 747 travelling at 160Mph and simply place it on a treadmill or spinning runway. There is still forward velocity to account for. Even if you could find a way to make the aircraft stop &quot;very fast&quot; without ripping the landing gears off (ie. the arresting gear suggested by Dan), think of the effect it would have on passengers. Consider going from 160Mph to 15Mph in only a few seconds. It's not comfortable, and for many people (think infants and elderly), it's not even safe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In regards to the aircraft turning, commercial airplanes are quite top-heavy, at least when compared to cars. Cars can turn very fast, even at high speeds (think NASCAR), because they are low to the ground. They have huge surface area on their tires in relation to the size and weight of the vehicle. Airplanes are the opposite. Compared to their size and weight, landing gears are very small, and not very useful for much else than rolling in a straight line.&lt;/p&gt;&#xA;" OwnerUserId="985" LastActivityDate="2014-02-25T23:52:14.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1939" PostTypeId="2" ParentId="1935" CreationDate="2014-02-26T00:26:54.907" Score="27" Body="&lt;p&gt;The operating procedures for the four airlines I worked for (2 commuters and two 747 carriers) all called for the flying pilot (which would be the first officer if it was their leg) to retain control of the airplane until all relevant checklists had been accomplished.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it is, of course, the captain's prerogative to take control at any point. That would, I think, be very unwise to do in the case of an engine failure during takeoff unless the first officer was really screwing up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The greater workload in the 747 during emergency/abnormal procedures lies with the non-flying pilot and the flight engineer (old 3 man cockpit 747-100s and -200s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recommended procedure at my last two airlines was, if the captain was flying at the time of the failure, to hand control to the first officer after all relevant checklists had been completed, to thus enable the captain to give his full attention to how best to proceed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My personal and observational experience is that there is little difference between captains and first officers at the 747 level insofar as control manipulation during go/no go situations on the runway in simulators. In fact, I could point you to an accident resulting in the total loss of a 747 when the flying pilot was the Captain, and he elected to abort 30 knots after $V_1$, thus insuring the aircraft would leave the runway.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="97" LastEditDate="2014-04-16T23:56:48.800" LastActivityDate="2014-04-16T23:56:48.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1940" PostTypeId="2" ParentId="1935" CreationDate="2014-02-26T00:29:51.687" Score="15" Body="&lt;p&gt;In airline operations, both pilots are trained to handle engine failures at any point during the flight, including during the takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as who actually flies when it happens, it is a matter of the airlines SOP's and could be different from airline to airline.  In general it is safer for whoever is flying when the engine fails to continue rather than attempting to transfer the controls.  After an engine failure during takeoff, the aircraft is in a relatively unstable condition which often needs high control forces and the person flying has already figured out how much control pressure is required to keep it flying like it is supposed to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain is &lt;strong&gt;always&lt;/strong&gt; the final authority when it comes to the safe operation of the flight though, so if he felt that it wasn't going well, he could take over at any point.  Many captains actually prefer to have the first officer fly during abnormal situations like this because they can then &quot;oversee&quot; more effectively without having to focus so much on actually flying the airplane.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-26T00:29:51.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1941" PostTypeId="2" ParentId="1937" CreationDate="2014-02-26T00:52:05.937" Score="9" Body="&lt;p&gt;A lot of the maneuvers can be learned and practiced at higher altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, the airshow pilots usually request a waiver from the FAA (to waive certain rules) so they can practice at lower altitudes.  The waiver will specify the location, hours of operation, who can use the waiver, which specific rules are waived (usually aerobatics within 4 NM of an airway, and/or certain altitude restrictions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, a lot of airshow pilots get their start competing in &lt;a href=&quot;http://www.iac.org&quot;&gt;IAC&lt;/a&gt; aerobatic contests.  This gives them the opportunity to learn the maneuvers and get some very experienced critiquing.  As they progress in the sport they attempt more difficult maneuvers at progressively lower (but still safe!) altitudes.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-02-26T00:52:05.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1942" PostTypeId="2" ParentId="1937" CreationDate="2014-02-26T00:57:00.737" Score="19" Body="&lt;p&gt;Aerobatic pilots typically use &quot;aerobatic practice areas&quot; when they practice.  Many of the Part 91 rules which would need to be broken in order to practice aerobatics are waived within these aerobatic practice areas (such as the 1,500 ft. &quot;floor&quot; for normal aerobatics in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.303&quot; rel=&quot;nofollow&quot;&gt;91.303&lt;/a&gt;(e)).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has to approve them, and &lt;a href=&quot;http://fsims.faa.gov/WDocs/8700.1%20GA%20Ops%20Insp%20Handbk/Volume%202/2_048_00.htm&quot; rel=&quot;nofollow&quot;&gt;their guidance&lt;/a&gt; includes a good description:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4. AEROBATIC PRACTICE AREAS.&lt;/strong&gt; Aerobatic competition pilots, airshow pilots, and others who wish to practice aerobatic maneuvers not&#xA;  necessary for normal flight and below an altitude of 1,500 feet above&#xA;  ground level (AGL) must use a waivered aerobatic practice area.  These&#xA;  areas are not to be considered airshow sites.  The aviation community&#xA;  uses these practice areas to establish and maintain proficiency as&#xA;  well as enhance competitive skills in all the recognized aerobatic&#xA;  maneuvers. They are established by the waiver applicant in conjunction&#xA;  with the local FSDO and may have dimensions of several miles in&#xA;  various directions or be as small as a contest box; i.e., a cubic box&#xA;  with a dimension of 3,300 feet on all sides. Inspectors should be&#xA;  receptive to the establishment of these areas, consistent with safety&#xA;  and the efficient use of the NAS.  It is imperative that the safety of&#xA;  all nonparticipating aircraft be considered when issuing a Certificate&#xA;  of Waiver or Authorization for an aerobatic practice area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An aerobatic practice area may be established over an airport if coordinated with airport management, and can be used to practice landings like those that Bob Hoover does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides the special rules in these areas, it is also a good way to warn other traffic that aerobatics could be taking place because they are listed in the A/FD and a NOTAM is issued whenever they are hot.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-11T19:09:54.157" LastActivityDate="2014-04-11T19:09:54.157" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1943" PostTypeId="2" ParentId="1910" CreationDate="2014-02-26T02:36:49.103" Score="9" Body="&lt;p&gt;The Part 121 regulation that governs low visibility takeoffs are specified in 14 CFR 121.651.  It references company OpSpecs and 91.175 and Part 97:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&quot;Standard&quot; takeoff minimums are specified in 14 CFR 91.175 and would be the highest of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Non-standard takeoff minimums specified on the airport charts (FAR 97)&lt;/li&gt;&#xA;&lt;li&gt;For aircraft, other than helicopters, having two engines or less — 1 statute mile visibility.&lt;/li&gt;&#xA;&lt;li&gt;For aircraft having more than two engines — 1⁄2 statute mile visibility.&lt;/li&gt;&#xA;&lt;li&gt;For helicopters — 1⁄2 statute mile visibility.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;OpSpec C056 is issued to all 121 carriers, and basically just spells out the &quot;standard&quot; takeoff minimums that I listed above, and specifies that RVR must be used if it is available on the runway.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;OpSpec C078 is normally issued and allows taking off with lower than standard visibility as long as the airport doesn't already have published higher than standard takeoff minimums.  This is a fairly involved OpSpec with several optional paragraphs, and operators may be approved for takeoff operations down to and including 300 RVR.  For those not familiar with the term, RVR (Runway Visual Range) is the distance that a pilot can see down the runway, measured by automatic equipment,  and is measured in feet in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It offers approvals for the following visibilities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1/4 SM / RVR 1600:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Touchdown zone RVR (or mid RVR if touchdown zone is inop) is controlling:&lt;/li&gt;&#xA;&lt;li&gt;Requires &quot;runway markings or runway lighting provide pilots with adequate visual reference to continuously identify the takeoff surface and maintain directional control throughout the takeoff run.&quot; (Basically as long as the pilot feels comfortable, but specifically mentions HIRL, CL, and RCLM as okay.)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;RVR 1000 (optional)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Touchdown zone RVR and rollout RVR (A mid-RVR report may be substituted for either if they are inop, but still must have two systems) are both controlling&lt;/li&gt;&#xA;&lt;li&gt;Requires Runway Centerline Lights (CL)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;RVR 500 (optional)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Touchdown zone RVR, mid RVR, and rollout RVR are all controlling (one may be inop)&lt;/li&gt;&#xA;&lt;li&gt;Requires Operative runway centerline lights (CL)&lt;/li&gt;&#xA;&lt;li&gt;Requires Runway centerline markings (RCLM)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;RVR 300 (optional)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Requires a takeoff guidance system&lt;/li&gt;&#xA;&lt;li&gt;Requires operative high intensity runway lights (HIRL)&lt;/li&gt;&#xA;&lt;li&gt;Requires operative runway centerline lights (CL)&lt;/li&gt;&#xA;&lt;li&gt;Requires serviceable runway centerline markings (RCLM)&lt;/li&gt;&#xA;&lt;li&gt;Front course guidance from the localizer (if applicable to the system used)&lt;/li&gt;&#xA;&lt;li&gt;Crosswind less than 10 knots&lt;/li&gt;&#xA;&lt;li&gt;Touchdown zone RVR, mid RVR, and rollout RVR are all controlling (one may be inop)&lt;/li&gt;&#xA;&lt;li&gt;Requires special training requirements for both the PIC and SIC&lt;/li&gt;&#xA;&lt;li&gt;Taxiways with operative taxiway centerline lighting must be available&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regulations/&lt;a href=&quot;http://www.jaa.nl/secured/Operations/WGs/Ad%20Hoc%20HUD-EVS/02%20Meetings/06-1/HuDEVS%20FAA%20AC%20120-29A.pdf&quot; rel=&quot;noreferrer&quot;&gt;Sample OpSpecs&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5ddf8e24352c3995f6c38c979ca35acf&amp;amp;node=14:3.0.1.1.7.21.3.34&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;§121.651 Takeoff and landing weather minimums: IFR: All certificate&#xA;  holders.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Notwithstanding any clearance from ATC, no pilot may begin a&#xA;  takeoff in an airplane under IFR when the weather conditions reported&#xA;  by the U.S. National Weather Service, a source approved by that&#xA;  Service, or a source approved by the Administrator, are less than&#xA;  those specified in—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The certificate holder's operations specifications; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Parts 91 and 97 of this chapter, if the certificate holder's&#xA;  operations specifications do not specify takeoff minimums for the&#xA;  airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.2.6.42&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;§91.175 Takeoff and landing under IFR.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Civil airport takeoff minimums. This paragraph applies to persons&#xA;  operating an aircraft under part 121, 125, 129, or 135 of this&#xA;  chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Unless otherwise authorized by the FAA, no pilot may takeoff from&#xA;  a civil airport under IFR unless the weather conditions at time of&#xA;  takeoff are at or above the weather minimums for IFR takeoff&#xA;  prescribed for that airport under part 97 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) If takeoff weather minimums are not prescribed under part 97 of&#xA;  this chapter for a particular airport, the following weather minimums&#xA;  apply to takeoffs under IFR:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) For aircraft, other than helicopters, having two engines or less—1&#xA;  statute mile visibility.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) For aircraft having more than two engines—1⁄2 statute mile&#xA;  visibility.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) For helicopters—1⁄2 statute mile visibility.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;C056, IFR Takeoff Minimums, Part 121 Airplane Operations - All&#xA;  Airports.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Standard takeoff minimums are defined as 1 statute mile visibility&#xA;  or RVR 5000 for airplanes having 2 engines or less and ½ statute mile&#xA;  visibility or RVR 2400 for airplanes having more than 2 engines.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. RVR reports, when available for a particular runway, shall be used&#xA;  for all takeoff operations on that runway. All takeoff operations,&#xA;  based on RVR, must use RVR reports from the locations along the runway&#xA;  specified in this paragraph.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. When a takeoff minimum is not published, the certificate holder may&#xA;  use the applicable standard takeoff minimum and any lower than&#xA;  standard takeoff minimums authorized by these operations&#xA;  specifications. When standard takeoff minimums or greater are used,&#xA;  the Touchdown Zone RVR report, if available, is controlling.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. When a published takeoff minimum is greater than the applicable&#xA;  standard takeoff minimum and an alternate procedure (such as a minimum&#xA;  climb gradient compatible with aircraft capabilities) is not&#xA;  prescribed, the certificate holder shall not use a takeoff minimum&#xA;  lower than the published minimum. The Touchdown Zone RVR report, if&#xA;  available, is controlling.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;C078, IFR Lower Than Standard Takeoff Minimums, 14 CFR Part 121 Airplane Operations - All Airports.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Standard takeoff minimums are authorized in operations specification&#xA;  paragraph C056. The certificate holder is authorized to use lower than&#xA;  standard takeoff minimums in accordance with the limitations and&#xA;  provisions of this operations specification as follows.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Runway visual range (RVR) reports, when available for a particular&#xA;  runway, shall be used for all takeoff operations on that runway. All&#xA;  takeoff operations, based on RVR, must use RVR reports from the&#xA;  locations along the runway specified in this paragraph.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. When takeoff minimums are equal to or less than the applicable&#xA;  standard takeoff minimum, the certificate holder is authorized to use&#xA;  the lower than standard takeoff minimums described below:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Visibility or runway visual value (RVV) ¼ statute mile or&#xA;  touchdown zone RVR 1600, provided at least one of the following visual&#xA;  aids is available. The touchdown zone RVR report, if available, is&#xA;  controlling. The mid RVR report may be substituted for the touchdown&#xA;  zone RVR report if the touchdown zone RVR report is not available.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Operative high intensity runway lights (HIRL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Operative runway centerline lights (CL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Serviceable runway centerline marking (RCLM).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) In circumstances when none of the above visual aids are available,&#xA;  visibility or RVV ¼ statute mile may still be used, provided other&#xA;  runway markings or runway lighting provide pilots with adequate visual&#xA;  reference to continuously identify the takeoff surface and maintain&#xA;  directional control throughout the takeoff run.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[NOTE: If an operator is not authorized RVR 1000 the POI will not&#xA;  select RVR 1000 in the OPSS. If the OPSS is not available the POI&#xA;  should delete subparagraph b(2), b(3), &amp;amp; b(4) from the word&#xA;  boilerplate.]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Touchdown zone RVR 1000 (beginning of takeoff run) and rollout RVR&#xA;  1000, provided all of the following visual aids and RVR equipment are&#xA;  available.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Operative runway centerline lights (CL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Two operative RVR reporting systems serving the runway to be used,&#xA;  both of which are required and controlling. A mid-RVR report may be&#xA;  substituted for either a touchdown zone RVR report if a touchdown zone&#xA;  report is not available or a rollout RVR report if a rollout RVR&#xA;  report is not available.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[NOTE: If an operator is not authorized RVR 500 the POI will not&#xA;  select RVR 500 in the OPSS. If the OPSS is not available the POI&#xA;  should delete subparagraph b(3), &amp;amp; b(4) from the word boilerplate.]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Touchdown zone RVR 500 (beginning of takeoff run), mid RVR 500,&#xA;  and rollout RVR 500, provided all of the following visual aids and RVR&#xA;  equipment are available.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Operative runway centerline lights (CL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Runway centerline markings (RCLM).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Operative touchdown zone and rollout RVR reporting systems serving&#xA;  the runway to be used, both of which are controlling, or three RVR&#xA;  reporting systems serving the runway to be used, all of which are&#xA;  controlling. However, if one of the three RVR reporting systems has&#xA;  failed, a takeoff is authorized, provided the remaining two RVR values&#xA;  are at or above the appropriate takeoff minimum as listed in this&#xA;  subparagraph.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) At foreign airports which have runway lighting systems equivalent&#xA;  to U.S. standards, takeoff is authorized with a reported touchdown&#xA;  zone RVR of 150 meters, mid RVR of 150 meters, and rollout RVR of 150&#xA;  meters. At those airports where it has been determined that the runway&#xA;  lighting system is not equivalent to U.S. standards, the minimums in&#xA;  subparagraphs a(1) or (2), as appropriate, apply.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Takeoff Guidance System, If Applicable. If the certificate holder&#xA;  is authorized to use takeoff minimums based upon the use of takeoff&#xA;  guidance systems, the minimums will be specified for the aircraft&#xA;  listed in the Table 1 below. The certificate holder shall conduct no&#xA;  other takeoffs using these takeoff minimums. If subparagraph c is not&#xA;  authorized, N/A will be annotated in each of the columns in the table.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Special provisions and limitations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Operative high intensity runway lights (HIRL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Operative runway centerline lights (CL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Serviceable runway centerline markings (RCLM).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Front course guidance from the localizer must be available and&#xA;  used (if applicable to guidance systems used).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) The reported crosswind component shall not exceed 10 knots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Operative touchdown zone, and rollout RVR reporting systems&#xA;  serving the runway to be used, both of which are controlling, or three&#xA;  RVR reporting systems serving the runway to be used, all of which are&#xA;  controlling. However, if one of the three RVR reporting systems has&#xA;  failed, a takeoff is authorized, provided the remaining two RVR values&#xA;  are at or above the appropriate takeoff minimum as listed in this&#xA;  subparagraph.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) The pilot-in-command and the second-in-command have completed the&#xA;  certificate holders approved training program for these operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) All operations using these minimums shall be conducted to runways&#xA;  which provide direct access to taxi routings which are equipped with&#xA;  operative taxiway centerline lighting which meets U.S. or ICAO&#xA;  criteria for CAT III operations; or other taxiway guidance systems&#xA;  approved for these operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The certificate holder is authorized to use the following takeoff&#xA;  minimums for the airplanes listed below.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Table 1 (N/A = Not Authorized) Airplane M/M/S Lowest Authorized RVR&#xA;  Required Takeoff Guidance System&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[NOTE: If an operator is not authorized pilot assessment the POI will&#xA;  not select this statement in the OPSS. If the OPSS is not available&#xA;  the POI should delete subparagraph d in its entirety from the word&#xA;  boilerplate.]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Pilot Assessment of RVR for Takeoff (if applicable). In&#xA;  circumstances when the touchdown zone RVR reporting system has failed,&#xA;  is inaccurate, or is not available, the certificate holder is&#xA;  authorized to substitute pilot assessment of equivalent RVR for any&#xA;  touchdown zone RVR report required by this operations specification&#xA;  paragraph provided that:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The pilot has completed the FAA-approved training program for&#xA;  visibility assessment in lieu of RVR, and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Runway markings or runway lighting is available to provide&#xA;  adequate visual reference for the assessment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-27T22:13:16.623" LastActivityDate="2014-02-27T22:13:16.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1944" PostTypeId="2" ParentId="1738" CreationDate="2014-02-26T04:12:48.487" Score="1" Body="&lt;p&gt;There are many factors to glide ratio of an airplane, but a good indication is the aspect ratio (see more here: &lt;a href=&quot;http://en.wikipedia.org/wiki/Aspect_ratio_%28wing%29&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; ). The aspect ratio tells us how &quot;slim&quot; the wing is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slimmer a wing, the less induced drag it will create. The downside is that the longer a wing is, the more parasitic drag it creates. So it is a tradeoff for glider designers. For low speed flight, the longer the wing, the better. But for high speed flight, a short wing is better. This can be seen in open class gliders, where the trend the past 30 years have been to create greater wingspan gliders. The last few years, this has changed, and glider manufacturers are now producing new generations of open class gliders that have shorter wingspans than their predecessors(in the case of the new Quintus vs its predecessor, the Nimbus 4: 23m vs 26,5m)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In gliders, a high aspect ratio in nearly all cases (there are exceptions) translate to a high glide ratio compared to low aspect ratio gliders. Examples of gliders from the same generation (or close to the same) and their aspect ratios and (theoretical) glide ratios:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(AR: aspect ratio; GD: glide ratio)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LS4: AR: 21,7; GR: 40&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ventus 1: AR: 23,7; GR:44 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Discus: AR 21,3; GR 42&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nimbus 3: AR 35,9; GR 58&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ASH25: AR 39,8; GR 60&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now an extreme example that has been produced in very few numbers; the ETA has an aspect ratio of 51,3 and a glide ratio of 72.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, enough about gliders! If we take airliners, then the Gimli Glider (Boeing 767) had a reported glide ratio of 12:1 in an emergency situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 767-200 has an aspect ratio of 8~, along with a glide ratio of (according to Wikipedia) 12:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An Airbus A340-300 has an aspect ratio of 10~, and a 737-NG with winglets has an aspect ratio also of 10~. On the other hand, a 787 has an aspect ratio of 11~.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But without factory numbers of any of the airliners, it would be hard to say. But in any case, going by the aspect ratio, the 787 should have a better glide ratio, compared to the other airliners i mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regards to the 787 wing features, then the leading edge sweepback is very popular among glider manufacturers today. There is also a noticable increased dihedral(wing bending upwards) further out the wing, this is also seen on gliders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard to suggest if these factors will increase the glide ratio of the 787 compared to other planes, as the wing is certainly designed for optimal performance at cruise speed, and the speed for best glide ratio is likely alot lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only conclusion i would guess at, is that because of an aspect ratio that is about 10% higher than comparable airliners, then the 787 gliders better (but i have no idea of how much). If i would have to ballpark it, i would guess somewhere around 16-18 in glide-ratio.&lt;/p&gt;&#xA;" OwnerUserId="988" LastActivityDate="2014-02-26T04:12:48.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1945" PostTypeId="2" ParentId="1898" CreationDate="2014-02-26T05:38:37.853" Score="5" Body="&lt;p&gt;As a pilot, it sounds terrible.  Even landing or taking off on a strip with a hump in the middle, so you cannot see the other end, dramatically increases the workload, and the degree of risk.  Not to say that it cant be done, when everything goes right, but if anything fails, then you raise the risk of a crash enormously.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And at the moment, the bottleneck is not getting to the airport, its waiting around to go through all the procedures when there that takes most of the time.  So its not much advantage to put an airport nearer the city anyway.  A better road, catering for airport traffic only, to further away, may well cut the transit time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I would rather land an aircraft somewhere where there are as few obstacles as possible.  Gives a much better chance of success when things go wrong.&lt;/p&gt;&#xA;" OwnerUserId="992" LastEditorUserId="992" LastEditDate="2014-02-26T05:53:59.223" LastActivityDate="2014-02-26T05:53:59.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1946" PostTypeId="2" ParentId="1934" CreationDate="2014-02-26T08:12:32.557" Score="14" Body="&lt;p&gt;Over Central Europe in the winter time, air becomes tremendously cold. Since warm bleed air from the compressor stage of a jet engine is used for cabin heating, the pilots might have set temperatures to maximum in order to warm the cabin.&#xA;But being in a climb, almost all power of the engines is required for lifting the aircraft, thus leaving only little excess bleed air to be used for heating. During normal days and outside air temperatures this should be enough, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By levelling out the aircraft, the engines are spooled back (less power required than in climb -&gt; hence more excess bleed air available -&gt; higher ability to warm the cabin in cruise than in climb). If the pilots/cabin attendants just didn't realize this circumstance rapidly enough, the cabin is being flooded with maximum heating air from the engines.&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2014-02-26T08:12:32.557" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1948" PostTypeId="1" AcceptedAnswerId="1949" CreationDate="2014-02-26T10:54:32.487" Score="10" ViewCount="2163" Body="&lt;p&gt;I know, flaps are mostly used during take-off or landing to generate both lift and drag simultaneously. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering if the pilot uses flaps to generate more lift so that they can climb in less distance (due to drag of flap) and possible reasons for doing it. I have an idea that the flight control system may prohibit flap deployment above a certain altitude or at higher speeds due to flap structural limitations.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="167" LastEditDate="2014-02-26T11:27:26.233" LastActivityDate="2019-02-18T17:31:29.853" Title="In the upper air, do pilots use flaps to generate lift as well slow down an aircraft?" Tags="&lt;flight-controls&gt;&lt;flaps&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1949" PostTypeId="2" ParentId="1948" CreationDate="2014-02-26T11:17:14.193" Score="8" Body="&lt;p&gt;It's a little complex, but here is a shot. Take a look at the following graph:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.navlog.net/wp-content/uploads/2012/10/PowerAvailable.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;graph http://www.navlog.net/wp-content/uploads/2012/10/PowerAvailable.png&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you can see is multiple airspeeds. For a plane, the rate of cruise is maximised around Airspeed B is reached- this is when the difference between power available and power required is the greatest and therefore the most excess energy is available for climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slope here indicates how much power is necessary for that airspeed- the steeper the curve, the worse it is. The value is really high for airspeeds all the way to left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were to deploy the flaps, you would sort-of shift the power required curve to left- adding drag, reducing the difference between the power available and power required, reducing the maximum rate and in the process increasing the power necessary. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kx7Uw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kx7Uw.jpg&quot; alt=&quot;lift&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.ppl-flight-training.com/images/lift_formula_details.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;ppl-flight-training.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the equation above, you want to increase lift. Yes, you can do this with flaps- it would increase CL. As you yourself state, it takes a lot of drag to use flaps and slats. Another option is to increase velocity. This is more efficient and uses less energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason we need is flaps is since as the velocity drops for landing, we need to increase the CL to maintain sufficient lift for landing. Airspeed for B for landing though is much too fast, so you want to slow down to the left side of the graph. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/1734/difference-between-flaps-and-slats&quot;&gt;this post&lt;/a&gt; on a little more detail on this relationship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for flap limitations, they appear to be 20,000 ft for the Boeing 737- Mostly because boeing found them unnecessary to use at higher altitude.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-18T12:46:43.437" LastActivityDate="2019-02-18T12:46:43.437" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="1950" PostTypeId="1" CreationDate="2014-02-26T11:39:50.453" Score="4" ViewCount="2270" Body="&lt;p&gt;What post flight checks are performed? Are they automatically or pilot initiated. If automatic, what are the possible conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, one of the conditions to start the postflight checks might be &quot;aircraft wheel speed below 30-40 knots&quot;.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="419" LastEditDate="2014-02-26T12:15:53.083" LastActivityDate="2014-02-26T16:06:17.217" Title="What are the general post flight sequence checks and do they start automatically? If so, when?" Tags="&lt;flight-planning&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1952" PostTypeId="2" ParentId="1950" CreationDate="2014-02-26T12:08:36.173" Score="3" Body="&lt;h1&gt;After landing checks&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;These checks are designed to take the aircraft from a landing configuration to a ground/taxi configuration shortly after exiting the runway.  In general, you may see things like:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Retract flaps / spoilers&lt;/li&gt;&#xA;&lt;li&gt;Transponder to 1200 / OFF / GND&lt;/li&gt;&#xA;&lt;li&gt;Landing light on, strobe lights off&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Shutdown checks&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;These checks are designed to configure the aircraft for shutdown once ground movement has stopped.  You'll see things like this:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Heater / air conditioner OFF&lt;/li&gt;&#xA;&lt;li&gt;Magnetos DEAD CUT CHECK&lt;/li&gt;&#xA;&lt;li&gt;Avionics MASTER OFF&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Postflight checks&lt;/h1&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;These checks are used once the aircraft has been shut down to make sure that it's secure or ready to be handed over to the next crew.  You'll see things like the following:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight log COMPLETE&lt;/li&gt;&#xA;&lt;li&gt;Cabin CLEAN&lt;/li&gt;&#xA;&lt;li&gt;Tie-downs SECURE&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-26T12:08:36.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1953" PostTypeId="2" ParentId="1937" CreationDate="2014-02-26T12:35:38.440" Score="3" Body="&lt;p&gt;In addition to what's already been mentioned, there's usually at least one day and more often several days of practice sessions at the field where the show is to take place before the actual event.&lt;br/&gt;&#xA;That allows the crews to familiarise themselves with the actual local conditions as well as the visual cues (&quot;hey, there's a tall red chimney right where I need to start my turn, handy&quot;).&lt;br/&gt;&#xA;And for &quot;buzzing the tower&quot;, you can of course practice that with anything really. A nice tall free standing tree for example, a chimney of an abandoned factory, anything tall and slender in an area where you're allowed to practice.&lt;br/&gt;&#xA;Or lacking that mark a spot on the ground and in your mind extend that up.&lt;br/&gt;&#xA;And oh, you can practice low altitude things at high altitude the same way, create an imaginary plane at say 10.000 feet, calibrate your altimeter to show 0 at that altitude, and now just fly like you would normally. Safe too, if you get things wrong and would end up flying into the ground, you now still have 10.000 feet before you splatter yourself.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-02-26T12:35:38.440" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1954" PostTypeId="2" ParentId="1950" CreationDate="2014-02-26T16:06:17.217" Score="4" Body="&lt;p&gt;All checklists are initiated by either the pilot flying (PF) when between takeoff and touchdown, and the captain (CA) on the ground.  In addition to checklists is the concept of flows, which are a muscle memory sequence of buttons to press / switches to flip / things to touch that are performed by the appropriate pilot before the checklist is called for.  The flows will happen automatically when the pilot responsible knows they should happen and the checklist will be called for when the responsible pilot is ready for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, when landing, the PF will perform the landing, the deceleration and sometimes the high speed turnoff before control is transferred to the CA for taxi.  Once the CA is taxiing and the airplane is cleared of the active runway, the FO will automatically start the after landing flow and call ground control.  Once taxi is underway, the CA will call for the after landing checklist.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once parked at the gate, both pilots will do their portion of the parking flow and then the CA will call for the parking checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, if no crew is waiting to receive the aircraft and you are not keeping the aircraft then the FO will perform the postflight inspection and the pilots will perform the terminating checklist.  If you are keeping the plane, the FO instead does a combined post/preflight inspection and begin normal pre-flight actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While these actions are all started by humans, the closest thing to automatic actions are the flows.  To summarize the above, with general criteria for starting flows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landed, clear of the active runway, CA has the plane -- perform after landing flow&lt;/li&gt;&#xA;&lt;li&gt;Parked at the gate -- perform parking flow.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each of these flows are backed up by checklists called for the CA.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-26T16:06:17.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1955" PostTypeId="1" AcceptedAnswerId="1957" CreationDate="2014-02-26T17:41:03.427" Score="20" ViewCount="14503" Body="&lt;p&gt;On airliners, are spoilers used in any part of flight other than landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1TTVN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="65" LastEditDate="2015-03-13T14:55:20.870" LastActivityDate="2015-03-13T14:55:58.140" Title="When can spoilers be used on airliners?" Tags="&lt;landing&gt;&lt;airspeed&gt;&lt;spoilers&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1956" PostTypeId="2" ParentId="1955" CreationDate="2014-02-26T17:49:00.723" Score="12" Body="&lt;p&gt;Certainly! Spoilers are used whenever there's a need to descend a little faster than the aircraft will with idle engines and just flying downwards with it's own drag. This happens quite often. Pilots will try to avoid it since it's not efficient use of fuel, but they usually can't in busy airspace where stuff happens quickly and there are fixed procedures to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i1.ytimg.com/vi/lQj8p_YXYPA/hqdefault.jpg&quot; alt=&quot;spoilers&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact if I remember correctly, many spoilers don't have speed limits so that they can be used in all stages of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also used for rejected takeoffs (RTO). Spoilers work by disabling the lift, so the more they are deployed, the more lift is reduced. This helps the descend, or puts more pressure on the wheels on the ground making the braking action more effective during landings and RTOs, especially when the ground is slippery.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.767" LastActivityDate="2014-02-26T22:22:47.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1957" PostTypeId="2" ParentId="1955" CreationDate="2014-02-26T17:52:28.297" Score="30" Body="&lt;p&gt;Spoilers have many uses, but first I want to distinguish types of spoilers.  Airplanes will typically have ground spoilers and flight spoilers and they work like they sound.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ground spoilers only open up on the ground -- these are usually much more detrimental to lift than the flight spoilers.&lt;/li&gt;&#xA;&lt;li&gt;Flight spoilers open when actuated by the pilots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Another type of spoiler is the spoileron, which is used on some airplanes like an aileron, that is to bank the airplane by destroying lift on one wing.&lt;/p&gt;&#xA;&lt;p&gt;Since you ask about use in the air, I will focus on flight spoilers.  When would I use flight spoilers?&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I want to descend faster&lt;/li&gt;&#xA;&lt;li&gt;I want to slow down quicker&lt;/li&gt;&#xA;&lt;li&gt;I want to descend and slow down&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;I want to descend faster&lt;/h3&gt;&#xA;&lt;p&gt;This can be broken down into three categories&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I screwed up and I need to make a crossing restriction&lt;/li&gt;&#xA;&lt;li&gt;The anti/ice system turned on (more on this below)&lt;/li&gt;&#xA;&lt;li&gt;I am initiating an emergency descent (abnormal)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The bit about a/ice comes from the fact that on many airplanes when a/ice is on there is a high demand for bleed air.  In the EMB-145 the FADEC bumps up idle thrust quite a bit to meet this demand and if you did not anticipate this in your descent planning, we were authorized to use our spoilers in icing conditions to aid in the descent.  This could be interpreted as an &amp;quot;I screwed up&amp;quot; case, but really isn't in my opinion.&lt;/p&gt;&#xA;&lt;h3&gt;I want to slow down faster&lt;/h3&gt;&#xA;&lt;p&gt;If there is a charted speed restriction, this may be useful.  Particularly if you have just prioritized the descent to meet a crossing restriction and now need to bleed off speed.&lt;/p&gt;&#xA;&lt;p&gt;You might need to start descending out of 10k feet ASAP, and need to be at 250 kts to do so, and in this case spoilers can be useful.&lt;/p&gt;&#xA;&lt;h3&gt;I want to descend and slow down&lt;/h3&gt;&#xA;&lt;p&gt;In a jet, this can be hard when clean.  Often the choice is descend &lt;strong&gt;or&lt;/strong&gt; slow down.  When you need to do both, spoilers can be a great help.&lt;/p&gt;&#xA;&lt;hr&gt;&#xA;&lt;p&gt;In the case of landing or rejected takeoff, all of the spoilers (including flight spoilers) should deploy automatically on most airplanes when the thrust levers are moved to idle, there is weight-on-wheels and you are above some threshold speed.&lt;/p&gt;&#xA;&lt;p&gt;In addition, spoilers are useful in some airplanes for roll control, in addition to airplanes with pure spoileron roll control.  I didn't spend much time on this topic as like the ground spoilers in landing and RTO, these are passive from a pilot point of view -- you aren't specifically controlling these spoilers, the flight control system is doing it for you.  In any case, the spoilers used for roll control are quite important during flight.&lt;/p&gt;&#xA;&lt;p&gt;As you can see, spoilers have many uses in flight and not just for landing.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-13T14:55:58.140" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="1958" PostTypeId="2" ParentId="1911" CreationDate="2014-02-26T20:54:32.030" Score="4" Body="&lt;p&gt;As SSumner says, the weather is your factor for season difficulty in flight training, and in large part these weather differences can be related to geographical location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the North US in winter time you have ice threats, for flight training ice is a no-go situation (most trainers are not approved for ice nor do they have a/ice capabilities).  For days with no ice, there is often an infinite plane of stratocumulus clouds that you need an IFR clearance to get above.  This can still be a go situation for maneuvers but makes ground-based navigation impossible to practice.  You also will typically encounter very strong winds as the weather clears behind mid-latitude cyclones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the South during the winter you have sporadic freezing rain and icing events, but without the frequency of the North. Your big threat instead are the spring and summer thunderstorm season.  On many days, if you respect the AIMs idea of tstorm avoidance, you might as well stay on the ground, because it just doesn't exist.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Florida You will have thunderstorms like clockwork daily, all year long.  You can fly before and after these storms and the sea breeze that drives these storms makes the timing and position fairly reliable to be avoided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the desert southwest you are dealing with high density altitudes due to the elevation and the heat.  This can make climb performance problematic but this can be remedied with a capable airplane.  This region can also be problematic for instrument training because you'll never get to log any actual instrument time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Texas north though Nebraska you can sometimes get intense low-level jets bringing moisture north out of the gulf.  This can result in very strong winds at the surface and gusty conditions in lowest few thousand feet, and this can be problematic for training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the lee of mountains with strong winds aloft (e.g. New Mexico north along the front range of the Rockies) you can experience turbulence, mountain waves and rotor clouds.  These can predicted by the winds aloft and can be avoided but may present days when training is best not conducted.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-26T21:04:45.893" LastActivityDate="2014-02-26T21:04:45.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1959" PostTypeId="1" CreationDate="2014-02-27T00:01:37.127" Score="31" ViewCount="72449" Body="&lt;p&gt;What happens to a turbine engine from the time that a start is initiated until stable idle is achieved?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can go wrong?&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2020-06-21T18:47:59.920" Title="How are turbine engines started?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;&lt;engine-starting&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1960" PostTypeId="2" ParentId="1959" CreationDate="2014-02-27T00:01:37.127" Score="44" Body="&lt;p&gt;The means of starting most turbine engines is high pressure bleed air.  This bleed source typically comes from an APU but may also come from an already running engine (crossbleed start) or an external &lt;a href=&quot;https://www.youtube.com/watch?v=XxLPl7v7zgE&quot; rel=&quot;noreferrer&quot;&gt;huffer cart&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some airplanes the start is completely FADEC controlled and need only be initiated and monitored by the flight crew, and in other airplanes certain steps must be manually initiated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The process below best describes a turbofan engine.  Read @Falk s answer for information on differences with turboprop engines.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Turbofan basics&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Refer to the image below (Credit: K. Aainsqatsi, Wikipedia): &lt;img src=&quot;https://i.stack.imgur.com/eEC2t.png&quot; alt=&quot;Turbofan diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The portions of the engine I will be referring to below are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The N1 fan, N1 shaft and N1 turbine which are displayed in green and labelled &quot;Fan/Low-pressure compressor&quot;, &quot;Low pressure shaft&quot; and &quot;Low pressure turbine&quot;.  These units are connected and move as one piece.&lt;/li&gt;&#xA;&lt;li&gt;The N2 compressor, N2 shaft and N2 turbine, displayed in purple and labelled &quot;High pressure compressor&quot;, &quot;High Pressure shaft&quot; and &quot;High pressure turbine&quot;.  These are connected and move as one, but independently of the N1 shaft.  Un-pictured is an accessory drive that is geared to the N2 shaft to drive engine accessories.&lt;/li&gt;&#xA;&lt;li&gt;The hot section, pictured yellow and labelled &quot;Combustion chamber&quot;.  This is home to a constantly burning fire in a jet engine. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Engine Start&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The process of the engine starting follows this basic formula&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Through the opening of bleed air valves, bleed air is sent to an air turbine starter.  These devices typically use the high pressure bleed air to spin and engage a centrifugal clutch connected to the engines accessory drive.  This in turn causes the N2 shaft within the engine to spin.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With the N2 shaft spinning, the N2 compressor and the N2 turbines are spinning.  This begins to force air through the engine from front to back.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With the accessory shaft and N2 shafts spinning, accessories should start working and this can be verified by oil pressure indications on the EICAS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With increased N2 rotation, ignition will be turned on.  These igniters are located in the hot section of the engine and produce small sparks.  There should be an indication on the EICAS that the ignition is active.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With further increase in N2 rotation, fuel flow will be introduced.  This will be verified on the EICAS.  Once fuel flow is noted, it is important that the next stop happen fairly soon.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Light off!  The fuel is lit by the ignition and now the fire burning in the hot section supplied by air from the compressor is producing thrust across the N2 and N1 turbines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the engine is producing thrust across on the N1 turbine, the N1 shaft is spinning the N1 fan and the EICAS will note this increase in N1 rotation.  N1 and N2 rotation speeds increase.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Above a N2 threshold, bleed air valves supplying the the air turbine starter will close and the starter disengage. The igniters will turn off at some N2 threshold.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The engine will settle into a stable idle thrust setting.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;What can go wrong?&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Hung start&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;N2 fails to spin up sufficiently for fuel flow to be introduced.  &lt;/li&gt;&#xA;&lt;li&gt;Each start has a time limit and the start will be aborted.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;No ignitors&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Abort the start and switch igniters.  &lt;/li&gt;&#xA;&lt;li&gt;Give MX a call.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Failure to ignite&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuel flow is introduced but light off has not occurred in a proper timeframe&lt;/li&gt;&#xA;&lt;li&gt;Fuel is building up in the engine and if light off does occur, it can be damaging.&lt;/li&gt;&#xA;&lt;li&gt;The start is aborted and dry motoring is performed to clear the engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ITT exceedence&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is usually a limitation in the inter-turbine temperature during engine start.&lt;/li&gt;&#xA;&lt;li&gt;If this is exceeded the start must be aborted&lt;/li&gt;&#xA;&lt;li&gt;This may require coordination with MX before another start is attempted.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The air turbine starter fails to disengage&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This must be corrected before departing&lt;/li&gt;&#xA;&lt;li&gt;In some engines, MX can correct this with the engine running.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The bleed air shutoff valve supplying the air turbine starter fails to close&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This may require an engine shutdown to remedy&lt;/li&gt;&#xA;&lt;li&gt;However, in some airplanes, this valve can be manually shut by MX with the engine running&lt;/li&gt;&#xA;&lt;li&gt;Coordination with MX required.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Runaway N1 or N2 &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the FADEC isn't managing fuel flow properly, the engine may not settle but continue to spin up.&lt;/li&gt;&#xA;&lt;li&gt;Abort the start.&lt;/li&gt;&#xA;&lt;li&gt;Coordinate with MX before attempting a restart.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;What about starting the engine in the air?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;If the engine suffers a flameout, an airborne restart may be attempted.  These starts typically happen one of a few ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crossbleed start&lt;/li&gt;&#xA;&lt;li&gt;APU start&lt;/li&gt;&#xA;&lt;li&gt;Windmilling start&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The APU start is essentially the same process as above.  The crossbleed start, which can also be done on the ground, merely substitutes a running engine at a high power setting to provide the bleed air for starting and is otherwise the same as above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The interesting start is the windmilling start.  The necessity for this means something bad has happened.  To need a windmilling start, this means that there are no bleed air sources to supply the air turbine starter.  This can mean that all engines are out and the APU is unavailable (BAD!), or merely that bleed valves to a shutdown engine have failed closed and are unable to be opened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the EMB-145 that I am familiar with, a windmilling start required descending at an airspeed between 260 KIAS and 320 KIAS and could not be attempted above FL250.  In short, you hope that the mass flow through the engine is enough to spin the N2 compressor as the ATS would.  With an N2 indication within the engines airstart envelope, you introduce spark and fuel and hope that the engine lights.  In the worst case, if you too slow and unable to provide enough airflow prior to light off, the engine can quickly overtemp and be damaged.  For this reason it is especially important to abort this kind of start as soon as an abnormality is detected.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-02-27T17:20:56.863" LastActivityDate="2014-02-27T17:20:56.863" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1961" PostTypeId="1" AcceptedAnswerId="1966" CreationDate="2014-02-27T00:32:12.687" Score="20" ViewCount="3348" Body="&lt;p&gt;From the pictures I have seen of airline simulators, it looks like the range of motion is limited to somewhat level flight. Are there any flight simulators, possibly military trainers, that can do a complete barrel roll?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="22726" LastEditDate="2018-10-16T03:02:06.057" LastActivityDate="2019-02-01T23:56:15.080" Title="Do any flight simulators go completely inverted?" Tags="&lt;flight-simulator&gt;&lt;inverted-flight&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1962" PostTypeId="2" ParentId="1768" CreationDate="2014-02-27T02:27:56.277" Score="3" Body="&lt;p&gt;You log simulated instrument time in an FFS, Full Flight Simulator.&#xA;The relevant FAR's are 61.4, 61.1(b)6.&lt;/p&gt;&#xA;" OwnerUserId="1014" LastEditorUserId="1014" LastEditDate="2019-04-26T07:59:23.953" LastActivityDate="2019-04-26T07:59:23.953" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="1963" PostTypeId="2" ParentId="1925" CreationDate="2014-02-27T02:47:53.993" Score="2" Body="&lt;p&gt;According to the AIM Section 4-6-8, the language to use with ATC is simply, &quot;Negative RVSM.&quot;  You have to say it on the request for an RVSM flight level, flight level change, or climb/descent through RVSM airspace.  You must also say &quot;Negative RVSM&quot; on check-in if currently at an RVSM flight level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NBAA provides a &lt;a href=&quot;http://www.nbaa.org/ops/cns/rvsm/20140203-navigating-the-streamlined-rvsm-authorization-process-an-overview.php&quot; rel=&quot;nofollow&quot;&gt;guide for navigating the RVSM approval process&lt;/a&gt;.  This guidance is fairly new, and indicates that approval through a prior operator of the airplane is acceptable.  Your FSDO will make the authorization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/enroute/rvsm/documentation/#docs_AIR&quot; rel=&quot;nofollow&quot;&gt;FAA RVSM Documentation&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1014" LastEditorUserId="1014" LastEditDate="2014-02-27T03:07:57.460" LastActivityDate="2014-02-27T03:07:57.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1965" PostTypeId="2" ParentId="1959" CreationDate="2014-02-27T03:24:34.663" Score="19" Body="&lt;p&gt;If you would like to know about jet engines, please read @casey's answer. It's very detailed and good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some turbine engines which are started a different way. We are talking about turboprop or turboshaft engines. A famous example is the PT6 turbine, delivering power to many small turbine-powered propeller airplanes like Beachcraft's King Air series and Piper's Cheyenne and JetProp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These engines consist of two parts, the gas generator and the free power turbine. The gas generator is pretty much a jet engine. It consists of an inlet, a compressor, an combustion chamber and a turbine. I don't know any turbo prop engine with a nozzle to create thrust, like a jet engine has one, but if one of you knows about it, I would be keen to read your comment. On a turboshaft engine the exhaust isn't at all used to generate thrust so some of them are even inverted (compressor at the rear part of the engine, but of cause still fed with air from an inlet directed forward). You maybe noticed that in some turboshaft driven aircraft the exhaust is very close to the prop - here's the reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second component is a free power turbine, driven by the exhaust of the gas generator, driving the propeller via a reduction gear box (free power turbine speed &gt; 30.000 RPM, prop speed &amp;lt; 3.000 RPM). In most engines these components are only held together by the engine case, that's why it's called free power turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we all have a basic idea of this kind of engine and can talk about the start sequence. A so-called starter generator is connected to the gas generator. Basically it's an electric motor powered by a battery (or any other DC power source) used to crank the gas generator shaft. Once the engine is started this motor can be used as a generator delivering DC power. If you look at the principles of an electric motor and a DC generator you'll see that they are technically the same. You only need to change some connections. This is usually done by operating a three position rocker switch 'start-off-generator'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The start sequence is pretty much the same as it is for a jet engine:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crank the gas generator's shaft with the starter&lt;/li&gt;&#xA;&lt;li&gt;At a specific rotation speed (usually 10-15%) add fuel&lt;/li&gt;&#xA;&lt;li&gt;Monitor the engine parameters&lt;/li&gt;&#xA;&lt;li&gt;Switch to the generator&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Usually the free power turbine starts turning the propeller very soon after fuel is added, anyway some engines are equipped with a propeller brake preventing the free power turbine section from spinning. This is useful to operate the gas generator section only to obtain electric or hydraulic, sometimes pneumatic power - some kind of APU. Aerospaitiale's ATR series is a famous example. The called it &quot;hotel mode&quot;.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="938" LastEditDate="2014-07-23T17:58:11.957" LastActivityDate="2014-07-23T17:58:11.957" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1966" PostTypeId="2" ParentId="1961" CreationDate="2014-02-27T03:27:17.290" Score="27" Body="&lt;p&gt;&lt;a href=&quot;http://www.pulseworks.com/products&quot;&gt;Pulseworks&lt;/a&gt; makes some full motion sims that are capable of inverted flight and infinite barrel rolls.  These sims fall into the entertainment category more than the training category, but they are full motion, in cockpit sims.  I have also been in a similar type of sim at a Harris/Boeing sponsored party in Seattle made by a company whose name I cannot remember that did the same thing.  That one in fact was capable not only of rolls but also loops and could be pretty violent (I wanted to see if it would spin... it did).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a &lt;a href=&quot;https://www.youtube.com/watch?v=19clWUMfo6Q&quot;&gt;video&lt;/a&gt; of one of the Pulseworks models.  They have some at the Udvar-Hazy center at IAD (free admission, and a shuttle from the terminal).  They cost a bit of money to get into.  They are also often setup in pairs so you can go into a dogfighting scenario with the box next to you.  Bring a friend.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="65" LastEditDate="2015-06-17T17:56:50.247" LastActivityDate="2015-06-17T17:56:50.247" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1967" PostTypeId="1" AcceptedAnswerId="1978" CreationDate="2014-02-27T07:26:38.937" Score="10" ViewCount="3169" Body="&lt;p&gt;Some larger airports in the US use land-and-hold-short (LAHSO) operations, meaning you're cleared to land, but only if you're able to do so without going beyond specific point (usually an intersecting runway) on the roll-out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What if you're forced to go around just before touch-down, perhaps even with the mains hitting the pavement, you will inevitably head straight for, and cross, that intersecting runway. Would there be a risk of colliding with aircraft operating on the intersecting runway?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="19" LastEditDate="2014-03-12T09:49:29.957" LastActivityDate="2014-03-12T09:49:29.957" Title="Can you go around with LAHSO in effect?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;landing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1968" PostTypeId="1" CreationDate="2014-02-27T07:48:58.600" Score="10" ViewCount="1003" Body="&lt;p&gt;The use of the phrase &quot;going around&quot; is specified by ICAO Doc 4444 as the phrase to use when we're aborting the landing and heading for&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;another lap in the traffic pattern if we're on a visual or VFR approach, or&lt;/li&gt;&#xA;&lt;li&gt;the appropriate missed approach procedure if we're on an instrument approach&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, in the US, I often hear the pilot saying &quot;going missed&quot; when breaking off an instrument approach. Is this standard phraseology in the US, or another one of those non-standard phrases which have gained footing? The 7110.65 only mentions the instruction &quot;go around&quot; (which incidentally is analogous, traffic pattern if visual, missed approach if on instruments), but doesn't say anything about the appropriate pilot phraseology. I couldn't find any reference in the AIM (chapter 4 section 2) either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I also often hear just &quot;missed approach&quot;, which I suppose would be appropriate when checking back in with approach, but not with the tower, although feel free to clarify that for me as well)&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-02-27T21:43:34.773" Title="Is the phrase &quot;going missed&quot; standard in the US?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;phraseology&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="1970" PostTypeId="2" ParentId="1967" CreationDate="2014-02-27T11:45:57.970" Score="5" Body="&lt;p&gt;There's always a risk with LAHSO and pilots can always say &quot;unable&quot;; student pilots are not even permitted to accept a LAHSO clearance. You can always go around if you deem it necessary; you're the pilot in control and empowered to make all decisions affecting the safety of your flight, and the fact that you're landing on a LAHSO clearance is just a factor you need to take into account. Making the decision to go around is, in my estimation, much safer than landing and potentially crossing the hold short line (due to the reaction time others have to deal with the situation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While there is that risk, the tower is watching and at any sign of trouble they will call other landing aircraft off. The two runways aren't being landed on at the same moment such that normal operations would cause them to collide at the intersection if one didn't hold short.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.aopa.org/News-and-Video/All-News/1999/April/1/Dont-get-LAHSOed.aspx&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; interesting article on the subject, there were 20 LAHSO incidents between 1994 and 1999.&lt;/p&gt;&#xA;" OwnerUserId="73" LastEditorUserId="73" LastEditDate="2014-02-27T14:49:46.267" LastActivityDate="2014-02-27T14:49:46.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1971" PostTypeId="1" CreationDate="2014-02-27T12:00:31.473" Score="17" ViewCount="32311" Body="&lt;p&gt;What rule of thumb would you use for your airplane insofar as how far from your destination you would begin your descent given an expected straight-in approach and landing in no-wind conditions and no ATC or traffic restrictions? How would your weight influence that rule of thumb, bearing in mind that the heavier you are, the more potential energy you have to dissipate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With those same conditions, what rule of thumb would you use to determine how close to the airport you could get before descending and still come straight in if you had an empty airplane save for necessary fuel and if you were allowed to use any aircraft configuration you wanted, and what would that configuration be?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1696" LastEditDate="2015-02-18T23:03:36.547" LastActivityDate="2020-04-01T17:15:33.333" Title="What is a rule of thumb for when to begin a descent?" Tags="&lt;flight-planning&gt;&lt;descent&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="1972" PostTypeId="2" ParentId="1971" CreationDate="2014-02-27T12:33:54.183" Score="5" Body="&lt;p&gt;Well, you did say 'for your airplane'...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a DA-42, with a cruise speed of 150kts, the game is to arrive at the FAF, at the intermediate approach altitude, at about 120kts. Or even better: be at that altitude and speed about 1NM before FAF so you still have 15 seconds to spare. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;5NM for each FL/1000' to descend (500fpm at 2.5NM a minute)&lt;/li&gt;&#xA;&lt;li&gt;+1 NM for each 10kts to slow down (usually it's 30kts so 3 NM). If I'm heavy(er) I'll use 1.5NM for each 10kts&lt;/li&gt;&#xA;&lt;li&gt;+1 NM for each 10mb above 1013, or minus for lower pressure&lt;/li&gt;&#xA;&lt;li&gt;+1 NM for spare&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For example: FL90 to 2000' at 1023 hPa&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's 7 flight levels, so 35 NM, plus 3 miles to slow down, plus 1 mile for the pressure correction, plus 1 mile to spare, total is ~40 miles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We're not pressurized so max descent is limited to 1000fpm: halving those 40NM to 20NM gives you the limit for a (semi-decent) slam dunk descent and landing, but it's not really a fair comparison in a light twin vs a big jet. With a gear down and full flaps this thing can descend over 4000fpm while still slowing down.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-02-27T12:33:54.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1973" PostTypeId="2" ParentId="517" CreationDate="2014-02-27T13:11:06.143" Score="5" Body="&lt;p&gt;One thing that is an eye opener to people in regard to tailwind landings is when I ask them about wind gradients at low altitudes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind is actually (supposed to be) measured about 10 meters above the runway. Because of surface friction that wind speed is going to decrease dramatically as you approach the runway surface. If that wind is a tailwind, as you approach the runway and flare your tailwind decreases and your indicated airspeed does what? increases, that's right.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So not only your ground speed is higher, but you just got a speed bump during your flare leading to a longer float.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-02-27T13:11:06.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1974" PostTypeId="1" AcceptedAnswerId="1976" CreationDate="2014-02-27T14:12:59.297" Score="17" ViewCount="11776" Body="&lt;p&gt;When aircraft is at high altitude, atmospheric pressure will be too low but inside aircraft pressure is maintained such that it is comfortable for crew and passengers. But how is it maintained?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand that at higher altitude pressure difference can be too large which can deform the plane than how this is handled.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="-1" LastEditDate="2014-02-27T19:05:57.113" LastActivityDate="2014-05-27T06:32:48.360" Title="How is the cabin pressure maintained inside aircraft?" Tags="&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1975" PostTypeId="2" ParentId="1971" CreationDate="2014-02-27T14:57:38.627" Score="12" Body="&lt;p&gt;For ATC planning of jet transport aircraft, 3NM per 1000 ft, plus 10 NM for deceleration is used as a rule of thumb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$FL300=3\times30+10=100NM$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the 10NM for deceleration will be consumed at around FL100. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weight should not change the descent distance a lot, it mainly affects the speed. The lighter the slower. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="97" LastEditDate="2014-04-18T03:22:55.580" LastActivityDate="2014-04-18T03:22:55.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1976" PostTypeId="2" ParentId="1974" CreationDate="2014-02-27T15:32:06.367" Score="23" Body="&lt;p&gt;Once the airplane is closed up, all doors and windows secure, pressurization comes down to the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;how much air is being pumped into the cabin?&lt;/li&gt;&#xA;&lt;li&gt;how much air is being let out of the cabin?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Air enters the cabin (on a jet powered airplane) through bleed air taps in the high pressure compressor of the engines.  This air is routed through &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_cycle_machine&quot;&gt;air cycle machines&lt;/a&gt;, or &quot;packs&quot; as they are commonly referred to.  The packs condition the air for temperature and humidity (typically taking all of the water out of the air) and then pump this air into the cabin at high pressure such that it is at the proper temperature after expansion to cabin altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air exits the cabin through outflow valves, which are typically at the rear of the pressure vessel.  These can be manually or computer controlled and will open and close to regulate how much air leaves the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To provide constantly fresh air, the incoming air from the packs is constantly supplied and as such the cabin pressure is almost entirely regulated by the outflow valves.  These valves have to be able to exhaust more CFM of flow than the packs can supply in order to let the cabin climb and when providing less CFM&#xA;than the packs the cabin will descend.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin altitude will be managed so that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;it stays below a maximum pressure differential with the ambient atmosphere outside,&lt;/li&gt;&#xA;&lt;li&gt;cabin altitude rate of change is limited,&lt;/li&gt;&#xA;&lt;li&gt;maximum cabin altitude is kept below 10k feet (and typically below 8k feet) such that supplemental oxygen is not needed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-27T15:32:06.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1977" PostTypeId="1" CreationDate="2014-02-27T17:43:06.653" Score="5" ViewCount="417" Body="&lt;p&gt;I am doing a project based on some data recorded from London Heathrow during October 2012, to quality control the data I need to know when aircraft flew past the detectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any online databases of when flights took off and landed at Heathrow during this period?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the data contains which runway the aircraft landed on that would also be desirable,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for the help&lt;/p&gt;&#xA;" OwnerUserId="281" LastEditorUserId="12220" LastEditDate="2016-02-15T15:30:03.247" LastActivityDate="2016-02-15T15:30:03.247" Title="Where can I find a list of past flights at LHR?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1978" PostTypeId="2" ParentId="1967" CreationDate="2014-02-27T18:07:40.610" Score="5" Body="&lt;p&gt;The AIM contains guidance on LAHSO operations and specifically says (in bold; I didn't add the emphasis in this case) that the clearance does not stop you from going around, but if one becomes necessary, the &lt;strong&gt;pilot&lt;/strong&gt; should avoid other aircraft and vehicles and notify ATC as soon as possible:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html&quot;&gt;AIM 4-3-11 Pilot Responsibilities When Conducting Land and Hold Short Operations (LAHSO)&lt;/a&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5. If, for any reason, such as difficulty in discerning the location of a LAHSO intersection, wind conditions, aircraft condition, etc.,&#xA;  the pilot elects to request to land on the full length of the runway,&#xA;  to land on another runway, or to decline LAHSO, a pilot is expected to&#xA;  promptly inform air traffic, ideally even before the clearance is&#xA;  issued. &lt;strong&gt;A LAHSO clearance, once accepted, must be adhered to, just&#xA;  as any other ATC clearance, unless an amended clearance is obtained or&#xA;  an emergency occurs. A LAHSO clearance does not preclude a rejected&#xA;  landing.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6. A pilot who accepts a LAHSO clearance should land and exit the runway at the first convenient taxiway (unless directed otherwise)&#xA;  before reaching the hold short point. Otherwise, the pilot must stop&#xA;  and hold at the hold short point. &lt;strong&gt;If a rejected landing becomes&#xA;  necessary after accepting a LAHSO clearance, the pilot should maintain&#xA;  safe separation from other aircraft or vehicles, and should promptly&#xA;  notify the controller.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And because I hear some pilots get the readback wrong, the next paragraph covers the proper way to read back a LAHSO clearance:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;7. Controllers need a full read back of all LAHSO clearances. Pilots should read back their LAHSO clearance and include the words, “HOLD&#xA;  SHORT OF (RUNWAY/TAXIWAY/OR POINT)” in their acknowledgment of all&#xA;  LAHSO clearances. In order to reduce frequency congestion, pilots are&#xA;  encouraged to read back the LAHSO clearance without prompting. Don't&#xA;  make the controller have to ask for a read back!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If there is &lt;strong&gt;any&lt;/strong&gt; doubt, don't accept the clearance in the first place.  If something happens after you have accepted it and you aren't positive that you will be able to hold short, go around as early as possible to maintain as much separation from whatever may be crossing your runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a lot more guidance in that section of the AIM which I would highly recommend that any pilot flying in to a large airport reads.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-02-27T18:07:40.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1979" PostTypeId="1" AcceptedAnswerId="1981" CreationDate="2014-02-27T18:15:06.537" Score="30" ViewCount="5258" Body="&lt;p&gt;When air is piped in from outside and into a pressurized cabin, it is also dehumidified in the process.  All airlines provide beverage service on even short-haul flights to combat the dryness of the air.  Why is it necessary to dehumidify cabin air?  &lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="1696" LastEditDate="2015-06-17T15:55:27.463" LastActivityDate="2015-06-18T07:30:59.683" Title="Why does cabin air have to be dehumidified?" Tags="&lt;cabin-pressure&gt;&lt;humidity&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1980" PostTypeId="2" ParentId="1977" CreationDate="2014-02-27T18:35:17.497" Score="2" Body="&lt;p&gt;If you're lucky, you might just get it for free (see &lt;a href=&quot;http://www.flightstats.com/go/About/businessSolutions.do&quot; rel=&quot;nofollow&quot;&gt;halfway down this page&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We have provided a data drop of historical flight information for&#xA;  specific airports or airlines, on a one-off basis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for the runway data, it's harder, since I don't know of any website which records it. You can have a look on &lt;a href=&quot;http://www.flightradar24.com/data/airports/lhr&quot; rel=&quot;nofollow&quot;&gt;Flightradar24&lt;/a&gt; for which runway is in use at the moment depending on the aircraft positions, but apart from that it's probably not going to be easy. You might want to email the airport directly and ask if they could provide a figure for that month for each runway, but I'll doubt that a single source has the details for each and every flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get to it, have fun sorting out 40,000 flights ;)&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-02-27T18:35:17.497" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1981" PostTypeId="2" ParentId="1979" CreationDate="2014-02-27T18:37:41.443" Score="27" Body="&lt;p&gt;A lot of consideration is placed on the airframe (which has to hold for 20+ years) rather than the passengers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the primary reasons is to slow corrosion of the  aluminium airframe. This is also why the Boeing 787 is a lot more humid - corrosion is no longer an issue in a composite fuselage (or a lot less at least). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/m01txt.html&quot;&gt;Boeing&lt;/a&gt; and the &lt;a href=&quot;http://www.economist.com/node/655691&quot;&gt;Economist&lt;/a&gt; sum it up nicely I think:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;the greatest issue lies with the &lt;strong&gt;cold fuselage skin interacting with&#xA;  moist air, which will condensate and speed up the rate of corrosion.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;But condensation in the &lt;strong&gt;gap between cabin and hull can be lethal.&#xA;  This gap contains much of an aircraft's wiring, and water can damage&#xA;  that wiring's insulation&lt;/strong&gt;. Such a problem is thought to have&#xA;  contributed to the loss of a Swissair DC-11 off the Atlantic coast of&#xA;  America a few years ago. Too much condensation causes other&#xA;  difficulties, as well. There have been cases when ice has built up&#xA;  inside the tailplanes of aircraft, causing their rudders to freeze and&#xA;  thus preventing their pilots from steering them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft such as a &lt;strong&gt;Boeing 747-400 can accumulate as much as 700kg of condensation before it reaches equilibrium&lt;/strong&gt;. Even though&#xA;  that is only about 0.17% of the 400 tonnes such an aircraft weighs&#xA;  fully laden, it is enough to cause problems for the pilot when he&#xA;  tries to trim the balance of the aircraft. And 700kg is about the&#xA;  weight of nine men. So the aircraft is carrying the equivalent of at&#xA;  least nine non-fare-paying passengers, in an industry where every&#xA;  extra kilogram affects fuel consumption and profit margins.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2014-02-27T22:49:27.030" LastActivityDate="2014-02-27T22:49:27.030" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="1982" PostTypeId="2" ParentId="1979" CreationDate="2014-02-27T18:42:19.843" Score="16" Body="&lt;p&gt;There are a couple of things that contribute to the dryness of cabin air:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Cabin air is drawn from engine bleed taps in the high pressure compressor.  This is ambient air, which at the flight levels is normally quite dry and then heated and compressed, which will lower the relative humidity, making it seem even drier.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The air cycle machine subsequently extracts moisture from this hot, high pressure air within the pack and used it to provide evaoprative cooling in part of the pack responsible for cooling the air flowing through it (The pack needs to extract heat so when air is expanded into the cabin it is cool enough - it does this with compression/expansion cycles and cooling).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the air coming out of the packs undergoes expansion to cabin pressure, it will cool down and this will help counteract some of the dry feeling by boosting relative humidity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The primary reason low humidity is desirable in most airplanes is that water contributes to corrosion and that is bad for the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 787 takes a new approach and provides pressurization and air conditioning with electric compressor motors instead of engine bleed air, and using this method (and a composite airframe) allows for much higher relative humidity in the cabin.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-02-27T18:42:19.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1983" PostTypeId="2" ParentId="1971" CreationDate="2014-02-27T18:44:11.313" Score="16" Body="&lt;p&gt;Descent planning for jets can get a little tricky at times, and you have pointed out some of the things to look at when deciding when to start down (assuming that ATC gives you the option to choose your own top of descent).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The descent point is dependant on your aircraft and how much drag there is at your descent speed.  Anything that adds more drag allows you to come down faster, but also makes the flight less efficient since you would have burned less fuel had you just started down earlier without the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical jet will descend with the engines at flight idle and the speed at the recommended descent speed, which is usually close to the maximum speed for the airplane.  A good rule of thumb for most jets would be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3 miles for each 1,000 ft. of altitude to lose + 1 mile for every 10 KIAS of airspeed that you need to lose before landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Example:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are cruising along at 38 thousand feet and landing at an airport with an elevation of 2 thousand feet which means that we need to lose 36,000 ft.  Let's say that we will be descending at 350 KIAS and need to slow to 150 KIAS for landing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Thousands of feet to lose: $38-2=36$ thousand feet&lt;br&gt;&#xA;  Tens of KIAS of airspeed to lose: $35-15=20$ tens of KIAS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Distance = $36\times3+20=128NM$ from your destination&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So in this case, we will start down 128 miles out.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various factors that can cause this to be a little off, the biggest being the wind.  As the descent progresses, you should mentally double check your progress.  In this case, maybe check when we have 20,000 ft to go (should be 80 NM out now) and when we have 10,000 ft to go (should be 50 NM out now).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one of your checks indicates that you are a little off, you can adjust your descent rate (adding a little power or using spoilers to descend more quickly) to get back on track.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A slight variation of this uses the same calculations, but instead of using the airport as the &quot;target&quot; altitude and speed, they use a point 30 miles from the airport at 10,000 ft above the airport at 250 KIAS.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The above method is enough to get someone started, and just &quot;works&quot; most of the time.  As a pilot becomes more comfortable with the math, they can start to make adjustments for other factors like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The effect of the winds at the various altitudes during the descent&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Headwinds mean that you can wait a little longer to descend&lt;/li&gt;&#xA;&lt;li&gt;Tailwinds mean that you should start down a little sooner&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Weight of the aircraft&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The lighter the aircraft, the &lt;strong&gt;later&lt;/strong&gt; you can start your descent.  (If this seems backwards, consider that when you are heavy it will push the airspeed higher faster as you lower the nose and you will have to raise it to keep from overspeeding.  When light, you can keep the nose further down and will therefore have a higher descent rate.) &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;The direction that you are approaching the airport from&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you are landing straight in you should start sooner&lt;/li&gt;&#xA;&lt;li&gt;If you are going to fly a downwind, base, and final, you can start a little later&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;ATC speed restrictions can prevent you from descending at your normal rate, so you may need to start down earlier.&lt;/li&gt;&#xA;&lt;li&gt;Inoperative equipment (i.e. spoilers, etc.) may keep you from descending as fast so you may need to start down earlier.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As far as the configuration of the aircraft, in order to get the most fuel efficient profile, I would keep it clean as long as possible and start the descent at a point where I could glide for the majority of the descent and configure on speed for a stabilized landing in the normal landing configuration for the aircraft.  If this is your goal, then the use of spoilers is an indication of poor planning!  ;-)&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="97" LastEditDate="2014-04-18T03:23:22.380" LastActivityDate="2014-04-18T03:23:22.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1984" PostTypeId="1" AcceptedAnswerId="1991" CreationDate="2014-02-27T18:56:23.713" Score="29" ViewCount="62481" Body="&lt;p&gt;I'm not sure if it's just in Boeing aircraft, but I've heard that Cost Index has something to do with flight planning but have no idea what it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is it for and how is it calculated? (I'm happy for the simple version of the calculation if it's too hard to explain)&lt;/p&gt;&#xA;" OwnerUserId="951" LastEditorUserId="13197" LastEditDate="2016-04-25T19:56:37.567" LastActivityDate="2019-02-20T05:17:12.880" Title="What is Cost Index?" Tags="&lt;flight-planning&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1985" PostTypeId="2" ParentId="1984" CreationDate="2014-02-27T19:01:40.857" Score="13" Body="&lt;p&gt;According to this &lt;a href=&quot;http://www.skybrary.aero/index.php/Cost_Index&quot;&gt;article&lt;/a&gt;, Cost Index of a flight is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ratio of fuel costs to all other costs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the lower the Cost Index, the lower the fuel burn in relation to the other operational costs of the trip.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This generally means flying the airplane slower and higher in order to conserve fuel, but that is offset by the higher maintenance costs due to the airplane being in the air longer and inspections becoming due sooner, so is true only to a certain point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a generic term, not specific to Boeing.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-27T21:50:40.677" LastActivityDate="2014-02-27T21:50:40.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1986" PostTypeId="2" ParentId="1984" CreationDate="2014-02-27T19:04:07.423" Score="10" Body="&lt;p&gt;While somebody else might be able to explain it better, Cost Index is the relationship between fuel use and flight time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;High Cost Index&lt;/strong&gt;: Fast flight, low crew times, high fuel use, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low Cost Index&lt;/strong&gt;: Slow flights, high crew times, low fuel use, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's always a complex compromise on what is best, and policies vary between airlines and how they use their aircraft. I don't think you can 'do' a calculation though in that sense, since it's a value which often comes from computer formulas.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-02-27T19:04:07.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1987" PostTypeId="1" AcceptedAnswerId="1989" CreationDate="2014-02-27T20:50:03.930" Score="9" ViewCount="3132" Body="&lt;p&gt;I'm aware of some aircraft that have systems to calculate weight and balance.  For those aircraft that don't have such systems, how does the pilot know they are within weight and balance limits?&lt;/p&gt;&#xA;" OwnerUserId="651" LastEditorUserId="100" LastEditDate="2020-05-04T08:57:36.537" LastActivityDate="2020-05-04T08:57:36.537" Title="Do airlines weigh passengers and baggage before loading the aircraft?" Tags="&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1988" PostTypeId="2" ParentId="1971" CreationDate="2014-02-27T20:50:46.413" Score="3" Body="&lt;p&gt;I don't generally plan for long straight-in approaches &amp;amp; descents as I rarely have occasion to do them, but barring any other restrictions the rule of thumb I use for VFR operations in an unpressurized light GA aircraft is &quot;Begin a cruise descent, at no more than 500 feet per minute, such that I arrive at the airport traffic pattern entry at pattern altitude.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could easily adjust that for a long straight-in to say &quot;…such that I intercept the glide path to the runway somewhere between 3 and 5 miles out without requiring major changes to the aircraft configuration (particularly power/pitch).&quot;, or for an instrument approach to say &quot;…such that I arrive at the appropriate fix at the desired altitude, per the approach plate&quot;.&lt;br&gt;&#xA;I imagine a similar rule of thumb could be established for pressurized/jet aircraft, possibly with a faster descent rate (since you don't have to worry about ear block on the way down). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This indirectly accounts for how much potential energy (altitude) you have to dissipate - you're considering your (ground)speed, starting/ending altitude, and the descent rate you want to maintain (which gives you the distance at which you want to start descending).&lt;br&gt;&#xA;The actual descent profile (and your speed profile during the descent) will of course also be modified by the speed and configuration you want when you reach the bottom of the descent - it probably isn't ideal to arrive on a 3 mile final doing 200kts over the ground unless a drag chute is part of your braking routine. (&lt;a href=&quot;https://aviation.stackexchange.com/a/1975/64&quot;&gt;The deceleration requirement is accounted for in the ATC planning formula DeltaLima describes&lt;/a&gt; which is also a good starting point for figuring out your descent - for light GA folks like me though you can probably work the speed profile in your head.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I can't really offer you much for the second half of your question (&quot;How close can you get?&quot;) -- That really depends on how high you are starting out (what's your cruise altitude?), the performance characteristics of the airplane (how quickly can you drop altitude?), and how aggressive you want to be as the pilot.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could conceivably get pretty close in my Cherokee at 5000ish feet AGL flying &quot;straight in&quot;, pull the throttle to idle, slip like my life depended on it, and make the runway without carrying &lt;em&gt;too much&lt;/em&gt; excess velocity, but it would be &lt;em&gt;particularly ugly&lt;/em&gt; to do so, and quite a bit of work for me at the controls.&lt;br&gt;&#xA;I would certainly put that in the category of &quot;abnormal operations&quot; (though I also  put that kind of stuff in the &quot;fun to try at a quiet airport with my CFI riding shotgun&quot; category).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-02-27T20:50:46.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1989" PostTypeId="2" ParentId="1987" CreationDate="2014-02-27T21:06:58.277" Score="7" Body="&lt;p&gt;While I'm not a pilot, I think it goes along these lines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Airlines typically assume a value for passengers depending on gender and age. This distribution in the cabin will typically be quite random and a little variation does not do any damage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Baggage however is weighed on the scales at check in. Each bag is&#xA;normally scanned as it is passed onto the plane, so that they know&#xA;where is bag is located. The values are then passed onto the pilots&#xA;who are able to work out that the numbers are ok. Sometimes there are preferences to load up bags in a certain way for fuel issues, so this is very important to make sure this is still resonable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These values are then plugged into computers or worked out manually on a paper loadsheet to make sure they are good and within limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact the weight systems you are referring to are quite unusual I think, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1850/do-some-airplanes-have-weighing-scales-on-the-landing-gear&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-26T08:42:36.247" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="1990" PostTypeId="2" ParentId="1968" CreationDate="2014-02-27T21:43:34.773" Score="8" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/PCG/pcg.pdf&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; (the closest thing to &quot;regulatory&quot; documentation regarding phrases pilots are supposed to use on the radio) there is no &lt;code&gt;GOING MISSED&lt;/code&gt; - there is &lt;code&gt;GO AROUND&lt;/code&gt; as an ATC instruction (and by analog &lt;code&gt;GOING AROUND&lt;/code&gt; as a pilot's response or notification to ATC to inform them the pilot is doing so), which covers both VFR and IFR operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;GO AROUND&lt;/strong&gt; −&lt;br&gt;&#xA;  Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised by ATC, a VFR aircraft or an aircraft conducting visual approach should overfly the runway while climbing to traffic pattern altitude and enter the traffic pattern via the crosswind leg. A pilot on an IFR flight plan making an instrument approach should execute the published missed approach procedure or proceed as instructed by ATC; e.g., “Go around” (additional instructions if required).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(There is also an IFR-specific &lt;code&gt;EXECUTE MISSED APPROACH&lt;/code&gt; in there.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;GOING MISSED&lt;/code&gt; is not proper/correct phraseology (though much like &quot;tally one&quot; or &quot;got 'em&quot; in place of &quot;traffic in sight&quot; it will generally be understood by ATC - probably with about the same grinding of teeth as the other two phrases get).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Informing ATC (tower or approach) that you are executing a missed approach by simply saying &lt;code&gt;N12345, Missed Approach&lt;/code&gt; &lt;em&gt;is&lt;/em&gt; correct phraseology however:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;MISSED APPROACH&lt;/strong&gt;−&lt;br&gt;&#xA;  a. …&lt;br&gt;&#xA;  b. A term used by the pilot to inform ATC that he/she is executing the missed approach.&lt;br&gt;&#xA;  c. …&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and is probably what should be used in place of &quot;Going Missed&quot;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-02-27T21:43:34.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1991" PostTypeId="2" ParentId="1984" CreationDate="2014-02-27T22:09:06.830" Score="34" Body="&lt;p&gt;The cost index is a number used in the Flight Management System (FMS) to optimize the aircraft's speed. It gives the ratio between the unit cost of time and the unit cost of fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With this number, and knowledge about the aircraft's performance, it is possible to calculate the optimal speed for the aircraft, which results in the lowest total cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speeds slower than the optimal speed will result in less fuel burn, but also in more flying time. The cost of the extra flying time outweighs the fuel savings at speeds below the optimum speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speeds faster than the optimal speed will result in more fuel burn, but also in less flying time. The saving of less flight time do not outweigh the fuel burn at speeds above the optimum speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A low cost index means that the cost of time is low or that fuel is expensive. It will result in a low speed. High cost index means high cost of time (e.g. passengers about to miss their flight connection) or low fuel price (rare these days). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the minimum cost index (0) only fuel counts. This will result in the aircraft flying at Maximum Range Cruise. At the maximum cost index only time counts. This will result in the aircraft flying at Maximum Cruise Speed (V&lt;sub&gt;mo&lt;/sub&gt; / M&lt;sub&gt;mo&lt;/sub&gt; with a buffer) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines generally have a standard cost index they use for planning and adjust them on a flight by flight basis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cockpitseeker.com/wp-content/uploads/goodies/ac/a320/pdf/data/CostIndex.pdf&quot; rel=&quot;noreferrer&quot;&gt;This document&lt;/a&gt; from Airbus explains the cost index in more detail.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14694" LastEditDate="2016-04-28T14:15:07.287" LastActivityDate="2016-04-28T14:15:07.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1992" PostTypeId="1" AcceptedAnswerId="1999" CreationDate="2014-02-28T09:11:35.730" Score="21" ViewCount="3657" Body="&lt;p&gt;From Virgin Galactic on SpaceShipTwo:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Windows in the passenger compartment will be 13 inches (33 centimeters) wide by 17 inches (43 centimeters) tall. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;IMO that's enormous for an airplane, especially for a spaceplane! But, wouldn't such large windows cause problems? The Concorde had particularly small windows (passengers say that it's almost passport book sized) to maintain the integrity of the airframe and cabin pressure if a window happened to crack at 60,000 feet AMSL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But wouldn't such a large window cracking at 110 km AMSL on SpaceShipTwo definitely cause cabin pressure to equalize to atmospheric pressure in seconds? What redundancy does SS2 have to prevent catastrophe in such an event?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="1696" LastEditDate="2015-10-07T14:34:36.473" LastActivityDate="2019-02-19T21:11:07.050" Title="How are Virgin Galactic's SpaceShipTwo's windows so large?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;windows&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1993" PostTypeId="1" CreationDate="2014-02-28T17:24:24.833" Score="12" ViewCount="2007" Body="&lt;p&gt;So when a pilot is flying along and suddenly hears a &quot;&lt;strong&gt;Climb...  Climb...&lt;/strong&gt;&quot; Resolution Advisory (RA) from ACAS/TCAS, we are trained to immediately climb to avoid a collision with another aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a reporting requirement in NTSB 830 which states (bold added by me):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=31e357409808e3de4b1d397d7dc8ef9b&amp;amp;node=49:7.1.4.1.12.2.1.1&amp;amp;rgn=div8&quot;&gt;49 CFR 830.5 -  Immediate notification&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The operator of any civil aircraft, or any public aircraft not&#xA;  operated by the Armed Forces or an intelligence agency of the United&#xA;  States, or any foreign aircraft &lt;strong&gt;shall immediately, and by the most&#xA;  expeditious means available, notify the nearest National&#xA;  Transportation Safety Board (NTSB) office&lt;/strong&gt; when:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(10) Airborne Collision and Avoidance System (ACAS) resolution&#xA;  advisories issued either:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When an aircraft is being operated on an instrument flight rules&#xA;  flight plan and &lt;strong&gt;compliance with the advisory is necessary to avert a&#xA;  substantial risk of collision between two or more aircraft&lt;/strong&gt;; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) To an aircraft operating in class A airspace.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So my questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is the phrase &quot;&lt;em&gt;compliance with the advisory is necessary to avert a substantial risk of collision between two or more aircraft&lt;/em&gt;&quot; defined somewhere or is there any guidance to say when the report is required?  I.e. is it anytime that we get an RA (even if we visually have the aircraft in sight), only if we actually respond to an RA, or is it if the two airplanes get within a certain distance from each other?&lt;/li&gt;&#xA;&lt;li&gt;When a report &lt;strong&gt;is&lt;/strong&gt; required, how do we report it and what information is required?  Is there a form that needs to be filled out?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-02-28T18:37:39.493" LastActivityDate="2016-07-05T07:05:15.920" Title="Another airplane almost hit me, but an ACAS Resolution Advisory told me to climb first. Now what?" Tags="&lt;tcas&gt;&lt;ntsb&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1994" PostTypeId="2" ParentId="1992" CreationDate="2014-02-28T18:50:00.450" Score="12" Body="&lt;p&gt;I think ultimately it's a business question.  Virgin Galactic is selling tours at a premium price where as Concorde was sold to move people from point a to point b.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With Concorde, since the point of the craft was to get people from point A to point B very very quickly, they put money into big engines and efficient aerodynamics.  The view doesn't really matter in that equation, but you do need structural integrity.  So they went with the cheapest way to get that structural integrity, small windows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Virgin Galactic, on the other hand, is selling an experience.  And frankly, if you're going into space the two biggest selling points are going to be zero gravity and, honestly, the view.  Hence, even though it will make the craft more expensive to reinforce properly, they are installing very large windows.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a note, airliner manufacturers could also install big old huge windows if they wanted as well, but do you want to pay another $50 a flight just to have a bigger window?  For most people the answer is no...hence small windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it's just a matter of figuring out what you are trying to sell and, then, putting money into that selling point.  It's what gets you a good return on your investment :).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS- lol, and after all that writing I appear to have answered the &quot;why&quot; and not the &quot;how&quot;.  Well, let the internet judge me as it will, I'll leave this answer up for now :).&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-02-28T18:57:32.050" LastActivityDate="2014-02-28T18:57:32.050" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="1995" PostTypeId="2" ParentId="1979" CreationDate="2014-02-28T19:48:55.723" Score="7" Body="&lt;p&gt;When I flew the C-141 and C-17, their environmental systems weren't intentionally dehumidifiers (designed to reduce the overall humidity), but they did push the air through a fabric bag called the 'sock' to capture droplets that formed during cooling.  As air continued to flow, that moisture could evaporate and rejoin the stream, or be vented overboard through a drain.&lt;br&gt;&#xA;At altitude, the air is very dry.  Flying through weather in the approach/departure environment could cause a lot of moisture to get ingested, and so needed to be sorted out.&lt;/p&gt;&#xA;" OwnerUserId="1033" LastActivityDate="2014-02-28T19:48:55.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="1996" PostTypeId="2" ParentId="1992" CreationDate="2014-02-28T20:15:39.540" Score="0" Body="&lt;p&gt;The Concorde had a lot of thermal expansion due to air/skin friction, that may have impacted window size.  SpaceShipTwo travels at much lower speeds, and doesn't have that issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, the issue is whether the window is designed to withstand the pressure differential of cabin to space.  As long as it is thick enough, made out of strong enough materials, they should work safely.&lt;/p&gt;&#xA;" OwnerUserId="1033" LastEditorUserId="1033" LastEditDate="2014-02-28T20:31:04.880" LastActivityDate="2014-02-28T20:31:04.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="1997" PostTypeId="1" CreationDate="2014-02-28T20:22:29.977" Score="18" ViewCount="5436" Body="&lt;p&gt;When operating a large turbine aircraft under 14 CFR 135, does the FAA allow a passenger to occupy the jump seat in the cockpit?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.jetcraft.com/wp-content/uploads/2013/06/Falcon900ex_sn83_cockpit_SS_-7490-462x308.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h3CiI.jpg&quot; alt=&quot;Falcon 900 jump seat&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;strong&gt;&lt;em&gt;Falcon 900 jump seat&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it matter whether or not they are a company employee (i.e. other than a flight crew member)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike the airlines, we usually fly with the cockpit door open (if there is even one installed) so it isn't a security issue like the airlines.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-12-02T18:51:07.080" Title="Is it legal for a passenger to sit on the jump seat in Part 135 operations?" Tags="&lt;faa-regulations&gt;&lt;far-135&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="1998" PostTypeId="1" AcceptedAnswerId="2000" CreationDate="2014-02-28T21:11:40.047" Score="13" ViewCount="2923" Body="&lt;p&gt;Is it an accepted practice to notify the tower of a radio failure by cell phone, and use the cell phone as a radio, or are there other ways of dealing with radio failure?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="1696" LastEditDate="2015-10-19T19:12:54.570" LastActivityDate="2015-10-19T19:12:54.570" Title="If the radio fails, can a pilot contact the tower by cell phone?" Tags="&lt;radio-communications&gt;&lt;cell-phone&gt;&lt;lost-communications&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-10-22T23:12:45.817" ContentLicense="CC BY-SA 3.0" />
  <row Id="1999" PostTypeId="2" ParentId="1992" CreationDate="2014-02-28T21:14:41.847" Score="21" Body="&lt;p&gt;Here are a few ideas:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;First and foremost, we're not handling metals here. Composites have the advantage of &lt;strong&gt;being able to be made stronger by adding on a few layers around high-stress&lt;/strong&gt; area like windows. This was difficult with metals since this needed some sort of fasteners or adhesives to do. This reinforcement is seen in the photo below.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The windows are designed to keep an even pressure all around in the context of the fuselage shape at that point. &lt;strong&gt;You'll notice the flange design which keeps the fuselage shape and stop it from popping open.&lt;/strong&gt; This is a little like the thicker part of a bottle neck. This is very difficult (if possible) to do well in a metal fuselage to this extent.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EWZIx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EWZIx.jpg&quot; alt=&quot;SpaceShipTwo&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://msnbcmedia.msn.com/i/MSNBC/Components/Photo/_new/090619-coslog-rutan-466px-1130a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;msn.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The usage is completely different. Concorde was a commercial aircraft, intended for many years of operation. This is a very low-cycle aircraft which will see a fraction of that flying. The &lt;strong&gt;number of pressurisation cycles is a lot lower&lt;/strong&gt;, putting much less force on the windows. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As for safety, the style of flying is completely different. Probably flown by test pilots, &lt;strong&gt;the aircraft might never even experience rain and will fly under very predictable conditions, with very few flight cycles&lt;/strong&gt;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Periods of &lt;strong&gt;elevated temperatures gradually degrades many materials, this is much less a concern with short flights&lt;/strong&gt;. If I gather correctly this is the main issue with sustained high-speed flight, as seen on Concorde and SR-71 and other aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m4eTQ.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m4eTQ.gif&quot; alt=&quot;profile&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://image.guardian.co.uk/sys-images/Guardian/Pix/maps_and_graphs/2008/07/28/virgin.galactic.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;guardian.co.uk&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Composites have a lot lower thermal expansion&lt;/strong&gt; (CFRP vs. Aluminium is an order of magnitude lower) which reduces issues with expansion in the fuselage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Concorde was a commercial aircraft with weight and operating price in mind. &lt;strong&gt;This aircraft is built for this purpose, with the windows considered as a main feature from the start&lt;/strong&gt;. You could probably have been able to make the windows a lot larger on Concorde, at the unacceptable price of weight, production and operating cost.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Needless to say that knowledge of materials and structures has advanced substantially, all our these features can be modelled in detail on computers, not necessitating the traditional conservative approach.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As for redundancy, predecessor SpaceShipOne had double pane windows and double seals everywhere. For the passengers without suits, if a window were to blow entirely, you're most probably out of luck.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-19T21:11:07.050" LastActivityDate="2019-02-19T21:11:07.050" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="2000" PostTypeId="2" ParentId="1998" CreationDate="2014-02-28T22:43:42.460" Score="15" Body="&lt;p&gt;As I pointed out in &lt;a href=&quot;https://aviation.stackexchange.com/a/1483/69&quot;&gt;another answer&lt;/a&gt; of mine, it is not legal to use a cell phone in flight, and as &lt;a href=&quot;https://aviation.stackexchange.com/a/1482/69&quot;&gt;another answer&lt;/a&gt; to the same question says, it really doesn't work very well anyway..&lt;/p&gt;&#xA;&lt;p&gt;Now, if the pilot has an emergency, they can exercise the emergency authority of the PIC as allowed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.2&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.3&lt;/a&gt;(b) to go ahead and use the cell phone.  If it is just the radio failure though, that isn't usually an emergency since there are other procedures in place for radio failures.&lt;/p&gt;&#xA;&lt;h2&gt;Radio Failure Procedures&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0604.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 6-4-1&lt;/a&gt; contains the procedures to use in the event of a radio failure.&lt;/p&gt;&#xA;&lt;p&gt;Basically, if the pilot is in visual conditions (VMC) and can remain that way, they should fly VFR (visually) and land as soon as practical.  If they can't remain in VMC then there are a number of rules which spell out the route and altitude that they should fly, as well as when they should start an instrument approach.&lt;/p&gt;&#xA;&lt;p&gt;Once they get to an airport they will still need to get clearance to land if it is a towered airport.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 4-3-13&lt;/a&gt; covers that, and basically the tower will communicate with the pilot via light gun signals:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://signallightgun.com/image_cache/files/stretch/exeter2_w500_h375/exeter2_09180820.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D4Z6A.jpg&quot; alt=&quot;light gun signal&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-02-28T22:43:42.460" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2001" PostTypeId="1" AcceptedAnswerId="2003" CreationDate="2014-02-28T23:58:06.877" Score="27" ViewCount="2924" Body="&lt;p&gt;According to Airbus:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;‐ After the flight crew selects reverse thrust, they must perform a full stop landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does it really make sense to have this limitation, and why? What happens if you realise there's not enough space to land, and you've still got adequate speed?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="15637" LastEditDate="2017-06-20T00:16:38.107" LastActivityDate="2018-08-08T23:43:13.767" Title="Why are you required to commit to a full stop landing if reverse thrust is selected?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;thrust-reverser&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2002" PostTypeId="2" ParentId="1993" CreationDate="2014-03-01T00:46:32.433" Score="11" Body="&lt;p&gt;Well, #2 is actually surprisingly easy. At the top middle of the &lt;a href=&quot;http://ntsb.gov&quot; rel=&quot;nofollow&quot;&gt;NTSB website&lt;/a&gt;, under &quot;Other ways to Contact NTSB&quot; there is an innocuous-looking link that says &quot;Submit a TCAS Notification&quot; (which has you send an email to &lt;code&gt;tcas@ntsb.gov&lt;/code&gt;).  Personally I'd follow that up with a phone call to &lt;a href=&quot;https://www.ntsb.gov/about/contact.html&quot; rel=&quot;nofollow&quot;&gt;the appropriate regional NTSB office&lt;/a&gt; as well, just to be sure you've discharged your obligation under NTSB 830.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The minimum required information for NTSB reporting is described in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a9143991dc8e92919654b531eb23d0e2&amp;amp;node=49:7.1.4.1.12.2.1.2&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;49CFR830.6&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Type, nationality, and registration marks of the aircraft;&lt;/li&gt;&#xA;  &lt;li&gt;Name of owner, and operator of the aircraft;&lt;/li&gt;&#xA;  &lt;li&gt;Name of the pilot-in-command;&lt;/li&gt;&#xA;  &lt;li&gt;Date and time of the accident;&lt;/li&gt;&#xA;  &lt;li&gt;Last point of departure and point of intended landing of the aircraft;&lt;/li&gt;&#xA;  &lt;li&gt;Position of the aircraft with reference to some easily defined geographical point;&lt;/li&gt;&#xA;  &lt;li&gt;Number of persons aboard, number killed, and number seriously injured;&lt;/li&gt;&#xA;  &lt;li&gt;Nature of the accident, the weather and the extent of damage to the aircraft, so far as is known; and&lt;/li&gt;&#xA;  &lt;li&gt;A description of any explosives, radioactive materials, or other dangerous articles carried. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is also a &lt;a href=&quot;https://www.tcasreport.com/&quot; rel=&quot;nofollow&quot;&gt;FAA website (www.tcasreports.com)&lt;/a&gt; which pilots are encouraged to use for reporting TCAS events - this site is not connected with the NTSB, and would not seem to cover that reporting requirement, but including the information that site asks for in your report to the NTSB would probably be helpful as well.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For #1 things seem a bit murkier: I too could not locate anything from the NTSB or in &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgadvisorycircular.nsf/key/ac%20120-55c?opendocument&quot; rel=&quot;nofollow&quot;&gt;FAA AC 120-55C&lt;/a&gt; that clearly defines &quot;necessary to avert a substantial risk of collision&quot;, but broadly I would imagine any &lt;em&gt;Resolution Advisory&lt;/em&gt; (&lt;strong&gt;RA&lt;/strong&gt;) is reportable, while Traffic Advisories (&lt;strong&gt;TA&lt;/strong&gt;) would not be.&lt;br&gt;&#xA;(The reportability of RAs would seem to be doubly true if you're operating in IMC, where you have no chance of visually assessing the hazard -- Complying with an RA there would seem &lt;em&gt;essential&lt;/em&gt; to me.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgadvisorycircular.nsf/key/ac%20120-55c?opendocument&quot; rel=&quot;nofollow&quot;&gt;AC 120-55C&lt;/a&gt; does allow a pilot to disregard a TCAS RA if they're certain that they have visual contact with the aircraft causing the RA - but it also cautions that it's difficult to be that certain:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless it is unequivocally clear that the target acquired visually is the one generating the RA and there are no complicating circumstances, the pilot’s instinctive reaction should always be to respond to RAs in the direction and to the degree displayed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Presumably in a case where you're operating in VMC, it's &quot;unequivocally clear&quot; that you're looking at the aircraft responsible for the RA, and it's &quot;unequivocally clear&quot; that the traffic does not pose a substantial risk of a collision then following the RA is not &quot;necessary to avoid a substantial risk of a collision&quot; (i.e. you wouldn't &lt;em&gt;have&lt;/em&gt; to report the incident).&lt;br&gt;&#xA;I'd err on the side of reporting those events anyway though: If nothing else it serves to make the NTSB aware that &lt;em&gt;something&lt;/em&gt; happened, and if they see a particularly large number of &quot;&lt;em&gt;somethings&lt;/em&gt;&quot; in a given area they may take that up with the FAA to try to isolate and address possible underlying causes...&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="19" LastEditDate="2016-07-05T07:05:15.920" LastActivityDate="2016-07-05T07:05:15.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2003" PostTypeId="2" ParentId="2001" CreationDate="2014-03-01T00:53:16.720" Score="28" Body="&lt;p&gt;The biggest problem is that thrust reversers take &lt;strong&gt;time&lt;/strong&gt; to move. During that time they are still producing reverse thrust (even if only at idle) and slowing you down. They must all completely close before you get forward thrust and can add power to start accelerating again.  Then, what happens if they don't stow, or only part of them stow?  Now you've used up valuable runway that could have been used to stop (or at least slow down more) and are no longer in a position to takeoff from. The consequences can be pretty severe. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-01T00:53:16.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2004" PostTypeId="2" ParentId="1837" CreationDate="2014-03-01T14:49:17.303" Score="1" Body="&lt;p&gt;Practically, you could likely do it and ATC would not notice; however, you are not technically adhering to the ATC clearance as it was provided to you and as you read back.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.123   Compliance with ATC clearances and instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) When an ATC clearance has been obtained, no pilot in command may&#xA;  deviate from that clearance unless an amended clearance is obtained,&#xA;  an emergency exists, or the deviation is in response to a traffic&#xA;  alert and collision avoidance system resolution advisory.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="287" LastEditorUserId="72" LastEditDate="2014-04-23T12:11:57.120" LastActivityDate="2014-04-23T12:11:57.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2005" PostTypeId="1" AcceptedAnswerId="2006" CreationDate="2014-03-01T15:24:48.973" Score="11" ViewCount="2190" Body="&lt;p&gt;Micro aerial vehicles are a special class of UAVs that have gained a lot of attention and research focus in the past few years. These are generally smaller in size ranging from 3m to 15 cm depending on where you look. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is there a clear, recognized or accepted definition of an MAV in terms of size and power? I am interested in the upper limits i.e. the line classifying a UAV as an MAV.&lt;/p&gt;&#xA;" OwnerUserId="193" LastActivityDate="2014-03-02T09:39:51.647" Title="What qualifies a UAV as an MAV?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2006" PostTypeId="2" ParentId="2005" CreationDate="2014-03-01T15:46:58.343" Score="5" Body="&lt;p&gt;Currently, there seems to be little official definition, and the term MAV appears is relatively new. The only &lt;a href=&quot;http://bulletin.pan.pl/%2855-1%2991.pdf&quot; rel=&quot;nofollow&quot;&gt;paper&lt;/a&gt; on the topic I could find that specifically approached the area defined it as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;small enough to be practical for a single-person transport and use.&quot; (Galiński and&#xA;  R. Żbikowski, 2007)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Delft University of Technology section on &lt;a href=&quot;http://www.delfly.nl/publications.html&quot; rel=&quot;nofollow&quot;&gt;MAV research&lt;/a&gt; provide no clear definition in their documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the definition seems to more subjective to the flying properties to the UAV, which might make the definition more difficult. Since they are not carrying people but sensors, they will be much more varying in weight, especially in with time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example, the &lt;a href=&quot;http://gizmodo.com/5981975/black-hornet-the-195000-spy-plane-that-fits-in-the-palm-of-your-hand&quot; rel=&quot;nofollow&quot;&gt;british army's MAV&lt;/a&gt; has a flight time of 25 minutes.  This one is a very small but has a respectable flight time. This will not simplify definition. I think the term coined by Galiński and Żbikowski is the most useful in a practical sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt; &#xA;University of Texas &lt;a href=&quot;http://design.ae.utexas.edu/humm_mav/introduction.html&quot; rel=&quot;nofollow&quot;&gt;page&lt;/a&gt; on the DARPA competion says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The definition employed in DARPAs program limits these aircraft to a&#xA;  size less than 15 centimeters (6 in.) in length, width, or height.&#xA;  MAVs must have a weight of 50 grams or less and must be capable of&#xA;  staying aloft for 20 to 60 minutes for a distance of 10 kilometers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pure source for this this, while not avaliable any longer, I believe I found to be &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The definition employed in DARPA's program limits these craft to a&#xA;  size less than 15 cm (about 6 inches) in length, width or height. &lt;a href=&quot;https://www.fas.org/irp/program/collect/docs/mav_auvsi.htm&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are currently no civilian classifications for UAVs from the FAA or EASA, hence the legal problem with these. Most army and air force drones operate under military exceptions if I'm not mistaken.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-02T09:39:51.647" LastActivityDate="2014-03-02T09:39:51.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2007" PostTypeId="1" AcceptedAnswerId="2008" CreationDate="2014-03-01T16:41:17.780" Score="24" ViewCount="3913" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Reverse_thrust&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some aircraft are able to safely use reverse thrust in flight, though the majority of these are propeller-driven. Many commercial aircraft cannot use reverse thrust in flight&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What are the repercussions to using reverse thrust while airborne?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="247" LastEditDate="2014-03-12T09:42:43.450" LastActivityDate="2014-03-12T09:42:43.450" Title="Why can't most jets safely use reverse thrust while airborne?" Tags="&lt;safety&gt;&lt;thrust-reverser&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2008" PostTypeId="2" ParentId="2007" CreationDate="2014-03-01T16:53:14.237" Score="22" Body="&lt;p&gt;The problems are two-fold:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The airspeed is much higher in flight than when landing, so the thrust reverser doors would have to be much stronger, and therefore heavier to withstand the additional forces, along with the relative wind making them harder to close. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What happens when it gets stuck in the deployed position?  Now you have to shut down a perfectly good engine and have additional drag on the airplane while in flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;(Bonus) It isn't really needed on most airplanes with spoilers, flaps, etc. that accomplish the same thing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-01T16:53:14.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2009" PostTypeId="2" ParentId="2007" CreationDate="2014-03-01T17:29:38.613" Score="12" Body="&lt;p&gt;The reversers on many jets significantly disrupt the air flow around the wing and are generally too powerful for use in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a crash, &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot;&gt;Lauda Air Flight 004&lt;/a&gt;, that was caused by uncommanded reverser deployment in flight. Granted, it was asymmetric deployment, but the report cites loss of lift from reverser deployment (itself, not loss of speed due to it's prolonged operation), which would occur for symmetric deployment too.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-03-01T17:29:38.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2010" PostTypeId="2" ParentId="2005" CreationDate="2014-03-01T18:36:39.413" Score="1" Body="&lt;p&gt;I wouldn't regard some of the large Hexacopters that can be transported and flown by one person as an MAV or even a craft like the Walkera QRx350 or a DJI Phantom; I would call these UAV's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These &lt;a href=&quot;http://droneflyers.wordpress.com/micro-quadcopters/&quot; rel=&quot;nofollow&quot;&gt;Mini and Micro Quadcopters&lt;/a&gt; are quadcopters but the MAV term could apply to fixed wing aircraft and helicopters below a certain size&lt;/p&gt;&#xA;" OwnerUserId="1040" LastEditorUserId="97" LastEditDate="2014-03-01T20:36:48.460" LastActivityDate="2014-03-01T20:36:48.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2011" PostTypeId="1" AcceptedAnswerId="2012" CreationDate="2014-03-01T18:51:02.583" Score="8" ViewCount="894" Body="&lt;p&gt;&lt;em&gt;This comes from a flight simulator experiment ages ago in the Boeing 737....&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm on the runway. I engage the heading switch, followed by the altitude and thrust. The aircraft lifts off, although hardly in a clean rotation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now I'm wondering: While it did work in the flight simulator, will the autopilot follow these commands in real life as well if I  repeated this in a business or commercial jet? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there anything stopping the autopilot from engaging a specified altitude or from following instructions which are utter nonsense?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-03-01T20:40:02.783" LastActivityDate="2014-03-01T20:40:02.783" Title="Are there any speed and altitude limitations on the autopilot?" Tags="&lt;safety&gt;&lt;autopilot&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2012" PostTypeId="2" ParentId="2011" CreationDate="2014-03-01T20:36:32.070" Score="10" Body="&lt;p&gt;It depends on the autopilot and you need to read the AFM to know what the limitations are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the business jets that I have flown prohibit the use of the autopilot below a specific altitude (between 50 and 1,000 feet depending on the autopilot and the configuration of the airplane). Nothing &lt;strong&gt;prevents&lt;/strong&gt; then from being used lower but it isn't allowed.  They will engage on the ground (in fact it is part of the required preflight tests) but have a specific prohibition against use for takeoff and landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airplanes and autopilots however are approved for autoland all of the way down to a full stop, and some for takeoff as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speeds also depend on the autopilot.  Some automatically disconnect if the aircraft receives a stall warning or overspeed signal but others don't. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-01T20:36:32.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2013" PostTypeId="1" AcceptedAnswerId="2145" CreationDate="2014-03-01T21:36:49.533" Score="8" ViewCount="2240" Body="&lt;p&gt;Are there any &lt;strong&gt;statistics on the most popular states to do private pilot flight training in the USA&lt;/strong&gt; or a similar measure? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know Florida is very well visited, but I was wondering if there were other states which also have high number of students.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-01T21:49:04.190" LastActivityDate="2014-03-10T04:22:36.297" Title="What are the most popular areas to do private pilot flight training in the United States?" Tags="&lt;flight-training&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2014" PostTypeId="1" AcceptedAnswerId="2016" CreationDate="2014-03-01T23:40:04.760" Score="12" ViewCount="2926" Body="&lt;p&gt;I am planning on making a pair of rudder pedals from scratch. I don't know whether they should be hinged, or slide forwards and backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On real aircraft, how do they work? Does it vary from plane to plane?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="167" LastEditDate="2014-12-10T12:32:40.387" LastActivityDate="2016-09-04T02:31:31.250" Title="Do rudder pedals slide or hinge?" Tags="&lt;flight-controls&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2015" PostTypeId="2" ParentId="1687" CreationDate="2014-03-02T00:55:34.730" Score="4" Body="&lt;p&gt;YouTube is really your best bet - is there any reason you wouldn't be able to use one of the many &lt;a href=&quot;http://youtu.be/_oIYiFyyGC4&quot; rel=&quot;nofollow&quot;&gt;NASA videos&lt;/a&gt;?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need a release for legal reasons NASA is famously liberal about granting rights to their research/educational videos - just contact then and you'll almost certainly get an official &quot;Sure, you can use it!&quot;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-02T00:55:34.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2016" PostTypeId="2" ParentId="2014" CreationDate="2014-03-02T01:37:11.907" Score="6" Body="&lt;p&gt;I've never seen &quot;sliding&quot; rudder pedals in a light GA plane - though there may be such designs in transport aircraft, especially fly-by-wire planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking for simplicity for a homebuilt aircraft or simulator I'd go with hinged pedals pivoting at the floor similar to what you'll find on a Piper Cub (which can be made by welding tubes together into an &lt;code&gt;I&lt;/code&gt; shape), or any number of similar floor-mounted designs:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/SmsxO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SmsxOm.jpg&quot; alt=&quot;Cub-Like pedals with square foot pads&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/sbTIv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sbTIvm.jpg&quot; alt=&quot;Cub rudder pedals with toe brakes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(As shown in the first picture, toe brakes can be easily retrofitted onto such a design, and as shown in the second you can mount square pedals on them if you want to, though the round bar has some advantages.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-02T01:37:11.907" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2017" PostTypeId="2" ParentId="2014" CreationDate="2014-03-02T03:47:54.720" Score="2" Body="&lt;p&gt;On the Cessna's I've flown they both slide and pivot- sliding directs the rudder, pivoting engages the respective wheel's brakes.&lt;/p&gt;&#xA;" OwnerUserId="296" LastActivityDate="2014-03-02T03:47:54.720" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2018" PostTypeId="2" ParentId="2013" CreationDate="2014-03-02T09:22:07.657" Score="1" Body="&lt;p&gt;I used to train in the Phoenix area. Very busy. Lots of chinese, vietnamese, dutch, germans, englishmen etc. (CAE Oxford, KLM Flight Academy (although I believe they recently ceased their training facility there) and many others. I'm sure this will not satisfy as an answer since these are all CPL training facilities and not PPL. Thought it would be interesting to share though. Cheers.&lt;/p&gt;&#xA;" OwnerUserId="1051" LastActivityDate="2014-03-02T09:22:07.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2019" PostTypeId="1" AcceptedAnswerId="2089" CreationDate="2014-03-02T10:42:41.983" Score="11" ViewCount="1227" Body="&lt;p&gt;I was watching some clips from &lt;em&gt;Catch Me If You Can&lt;/em&gt; starring Leonardo DeCaprio as Frank Abagnale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering- If brought a ticket on an airline today, &lt;strong&gt;came dressed up like a pilot, would you, be able to sit in the cockpit?&lt;/strong&gt; (assuming pilots are normally allowed to jumpseat in that jurisdiction) Say you come onboard the plane and present them a fake ID at the door. Is there anything to prevent this from happening, or are we still as vulnerable to this type of trick like in the movie?&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-03-07T05:47:19.920" Title="Is it possible to bluff one's way to the flightdeck like in Catch Me If You Can?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2020" PostTypeId="2" ParentId="2013" CreationDate="2014-03-02T16:30:43.170" Score="2" Body="&lt;p&gt;There are two popular areas:  1) Where you live.  Most pilots desiring to fly for fun train near their home and family, and 2) Where the weather is good.  aka somewhere down south, Arizona and Florida are the most popular.  Why?  Fewer no-fly days.  There is a reason that ERAU has branches in Florida and Arizona.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-03-02T16:30:43.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2021" PostTypeId="1" AcceptedAnswerId="2022" CreationDate="2014-03-03T00:11:25.500" Score="46" ViewCount="17168" Body="&lt;p&gt;What problems do cell phones cause? How is using a cell phone in the air different than using it from the ground?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-03-19T07:31:21.430" LastActivityDate="2019-07-13T15:36:07.983" Title="Why aren't cell phones allowed to be used in aircraft?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;electronics&gt;&lt;cell-phone&gt;" AnswerCount="8" CommentCount="5" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2022" PostTypeId="2" ParentId="2021" CreationDate="2014-03-03T00:24:59.720" Score="31" Body="&lt;p&gt;&lt;strong&gt;Why aren't cell phones allowed?/ What problems to cell phones cause?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of these cases apparently originate from a series of &lt;a href=&quot;https://www.livescience.com/5947-real-reason-cell-phone-banned-airlines.html&quot; rel=&quot;noreferrer&quot;&gt;unexplained events&lt;/a&gt; in the 90s which were believe to be caused by electronic gadgets, hence the ban. This was when cell phones appeared, and there was an aggressive ban as a result. NASA has a &lt;a href=&quot;https://asrs.arc.nasa.gov/docs/rpsts/ped.pdf&quot; rel=&quot;noreferrer&quot;&gt;list&lt;/a&gt; which includes some of these and makes for an interesting read. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now however an increasing list of airlines is allowing them again, depending on jurisdiction. FAA is &lt;a href=&quot;https://www.wired.com/2013/10/faa-ban-lifted/&quot; rel=&quot;noreferrer&quot;&gt;working on allowing it&lt;/a&gt; from a regulatory standpoint. Bear in mind that phones were probably much more powerful back when these rules were introduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mythbuster (episode 6, 2006) did a test on this by sticking in a powerful transmitter into a business jet. Their &lt;a href=&quot;https://web.archive.org/web/20140715091521/http://www.discovery.com/tv-shows/mythbusters/mythbusters-database/cell-phones-interfere-plane-instruments.htm&quot; rel=&quot;noreferrer&quot;&gt;website&lt;/a&gt; gives a slightly different version: It was the FCC, not the FAA, who led the way for this regulation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Explanation: Never mind what the chatterbox in the seat next to you&#xA;  says about cell phones messing with plane navigation — those metallic&#xA;  birds are built airtight against foreign signals and operate on&#xA;  entirely different frequencies than cell phones.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;So why all the fuss about phones? When you make a call at 10,000 feet,&#xA;  the signal bounces off multiple available cell towers, rather than one&#xA;  at a time. That means too many phone-happy jetsetters might clog up&#xA;  the networks on the ground, which is why the Federal Communications&#xA;  Commission (FCC) — not the Federal Aviation Administration (FAA) — banned&#xA;  cell use on planes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How is using a cell phone in the air different than using it from the ground?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it sensible to allow them on aircraft? To quote one of the above sources:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;although the FAA recommends that you still switch to airplane mode&#xA;  because you’re not going to get a signal 30,000 feet in the air — the&#xA;  only hit you’ll take is a dead battery when you land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's probably not a huge loss if you're flying commercial aircraft at 10,000 meters. In any case, you can't expect a service like you do on the ground, unless like Lnafziger says that the aircraft is equipped with a cellular basestation called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Picocell&quot; rel=&quot;noreferrer&quot;&gt;Picocell&lt;/a&gt;, illustrated below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7jdm6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7jdm6.jpg&quot; alt=&quot;picocell&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://luckybogey.files.wordpress.com/2009/06/infographietelmobile_en.jpg?w=640&quot; rel=&quot;noreferrer&quot;&gt;wordpress.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-07-13T15:36:07.983" LastActivityDate="2019-07-13T15:36:07.983" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="2023" PostTypeId="1" AcceptedAnswerId="2024" CreationDate="2014-03-03T06:34:29.000" Score="14" ViewCount="12583" Body="&lt;p&gt;My instructor made &quot;request right closed traffic...&quot; call before practicing a series of landings. Just wondering, what is the difference between this request and a &quot;stay in the pattern...&quot; request? Which one should I use when?&lt;/p&gt;&#xA;" OwnerUserId="1054" LastEditorUserId="6886" LastEditDate="2015-10-15T05:36:19.173" LastActivityDate="2015-12-30T20:27:37.300" Title="What is the difference between &quot;closed traffic&quot; vs &quot;stay in the pattern&quot; request?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2024" PostTypeId="2" ParentId="2023" CreationDate="2014-03-03T06:50:02.707" Score="14" Body="&lt;p&gt;Actually, &quot;stay in the pattern&quot; is non-standard phraseology and shouldn't be used, even though it means the same thing as &quot;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;nofollow&quot;&gt;closed traffic&quot;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifying the direction isn't required but it is a good idea to ensure that everybody is thinking the same thing.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="62" LastEditDate="2015-12-30T20:27:37.300" LastActivityDate="2015-12-30T20:27:37.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2025" PostTypeId="1" AcceptedAnswerId="2029" CreationDate="2014-03-03T06:52:01.587" Score="7" ViewCount="7830" Body="&lt;p&gt;My understanding is Pitch Trim should hold current Pitch position, Roll Trim should hold roll position and Rudder Trim should hold Rudder position to relieve pilot of holding the yoke/stick or pedal continuously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why there is Up-Down/Left-Right (Pitch/Roll) switches on yoke or stick?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appreciate, explanation of trim fundamental with respect to this.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="69" LastEditDate="2014-03-03T07:17:07.497" LastActivityDate="2015-04-30T08:25:56.430" Title="Why Pitch Trim Up/Down &amp; Roll Left/Right switches on yoke or control stick?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;trim&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2026" PostTypeId="2" ParentId="2025" CreationDate="2014-03-03T07:16:33.807" Score="3" Body="&lt;p&gt;The basic idea is that you adjust trim to relieve the control forces that you would otherwise have to hold.  For instance, any time that you change airspeed, the amount of air passing over the elevator changes and changes the amount of nose up/down force that it creates, requiring you to hold pressure forward or aft on the yoke in order to maintain the new airspeed.  You would then adjust the pitch trim to neutralize that force so that you don't have to hold it. Because airspeed (and therefore pitch trim) is changed so often during the flight when hand flying the aircraft, it is very convenient to be able to adjust it right on the your where you hands already are.   Not as many airplanes have aileron trim on the yoke since you don't need to change it as often, but the idea is the same. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-03T07:16:33.807" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2027" PostTypeId="5" CreationDate="2014-03-03T07:52:29.517" Score="0" Body="&lt;p&gt;Instrument flight rules (IFR) are a set of regulations governing aircraft operations. IFR regulations allow a qualified pilot in a suitably equipped aircraft to fly and navigate using only instruments, without any visual reference outside the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR may be required because of weather conditions, airspace rules or for other reasons, but a pilot may choose to operate a flight under IFR even when there is no requirement to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR is usually contrasted with VFR (&lt;a href=&quot;/questions/tagged/visual-flight-rules&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;visual-flight-rules&amp;#39;&quot; rel=&quot;tag&quot;&gt;visual-flight-rules&lt;/a&gt;); all flights operate under either IFR or VFR. IFR should not be confused with &lt;a href=&quot;/questions/tagged/imc&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;imc&amp;#39;&quot; rel=&quot;tag&quot;&gt;imc&lt;/a&gt; (instrument meteorological conditions), which are weather conditions in which IFR is required.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Useful Resources:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Flight Rules&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Meteorological Conditions&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="72" LastEditorUserId="22726" LastEditDate="2019-03-25T05:55:33.187" LastActivityDate="2019-03-25T05:55:33.187" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2028" PostTypeId="4" CreationDate="2014-03-03T07:52:29.517" Score="0" Body="Instrument flight rules (IFR) are a set of regulations governing aircraft operations. IFR permits flying and navigating by instruments alone in conditions where there is no visual reference outside the aircraft." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-03-03T12:26:23.197" LastActivityDate="2014-03-03T12:26:23.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2029" PostTypeId="2" ParentId="2025" CreationDate="2014-03-03T09:07:55.610" Score="14" Body="&lt;p&gt;I might be mistaken, but it appears to me that you're missing an important piece on how trimming works. It's not a button you press to magically remove the control forces, but rather, you need to adjust the trim tabs (on most smaller aircraft at least, some aircraft, especially new large ones, have other mechanisms, but that's outside the 'basics' scope) to achieve the desired result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll use the elevator as an example, but it applies to ailerons and rudder as well. This is a common image used when showing trim tab movement:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0jiv.jpg&quot; alt=&quot;Trim tab movement&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the trim tab extends into the airflow, pushing the elevator in the other direction. This is key though, as it's using airflow, its effectiveness diminishes when airspeed is reduced and it becomes more effective when airspeed is increased, which is exactly how the elevator itself is affected. This means that, should the airspeed change, both elevator and trim-tab will be affected the same way and the forces, and as a consequence the elevator deflection, will remain in an equilibrium. Maintaining a specific elevator deflection will cause the (aerodynamically stable) aircraft to remain at a selected angle of attack and therefore airspeed. In order to change airspeed, you need to change angle of attack, and so you need select a different elevator deflection, prompting the need to 're-trim' fairly often during a flight, especially during departure and approach. This applies to elevator trim, I've never flown with (in-flight adjustable) aileron or rudder trim, but I assume it is primarily used to counter effects of engine torque and P-factor, so it would be adjusted whenever you're changing the power setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could, theoretically, skip the trimming step and hold it with arm strength, but your arms would eventually go numb and it would be virtually impossible to keep it on airspeed while accomplishing the other tasks in the cockpit during high workload periods. The March/April 2014 issue of &lt;a href=&quot;http://www.faa.gov/news/safety_briefing/&quot; rel=&quot;noreferrer&quot;&gt;FAA Safety Briefing&lt;/a&gt; talks a bit about trimming, and mentions that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law&quot; rel=&quot;noreferrer&quot;&gt;Weber-Fechner law&lt;/a&gt;, which discusses the concept of &lt;a href=&quot;http://en.wikipedia.org/wiki/Just-noticeable_difference&quot; rel=&quot;noreferrer&quot;&gt;Just-noticeable difference&lt;/a&gt;, states that you need about 14% of difference to the pressure you're manually holding to notice a difference, so trusting the feel of your hand pulling the yoke is not a particularly good idea. I do believe some aircraft, in particular larger ones, would require more force than humanly possible for the needed elevator deflection in certain situations, suggesting the need to use trim, but I might be mistaken on that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The movement of the trim tab is sometimes driven by an electric motor (or otherwise powered, hydraulics for example) in which case you have up and down buttons, and sometimes it's manual, in which case you usually have a wheel which can be rotated to pull the tabs up or down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Up and down, which is often referred to as 'nose up' and 'nose down', signify what kind of control forces you want to remove. If you find yourself constantly pulling the nose up to maintain the desired airspeed and attitude, you'll need to apply nose up (or 'up') trim while simultaneously releasing the back pressure and vice versa. This sounds harder than it is, it just means you hold the yoke in place, and you will notice the amount of pressure needed to hold it there drops until it's completely gone. This is one of those things which is actually harder to do in a home simulator than in real life, as you'll have to move the control while applying trim. Note that the 'up' and 'down' labels do &lt;em&gt;not&lt;/em&gt; mean the tab will move up or down, remember the tab travels in the opposite direction of the elevator, and to pull the nose up, the elevator needs to move up into the airflow, meaning the tab will actually move down, as can be seen in the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bonus; in aircraft with no autopilot and autothrottles, if you do not apply any control forces the aircraft (aerodynamically stable) will maintain a particular airspeed. This means that for a specific configuration (flaps, landing gear, weight, power, etc) it's possible to trim the aircraft for a specific speed, this is very handy when it's crucial to maintain a specific airspeed such as during departure or approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This also means, which might not be obvious for someone not familiar with aircraft, that it's not possible to trim an aircraft to maintain altitude. Sure, there's usually a specific airspeed which will keep the aircraft in level flight, but that's only until you enter the next up- or downdraft, or until you've burned off a bit of fuel and aircraft has become lighter. So you will either need constant speed or power adjustments to keep it on altitude, most aircraft without autothrottles use the former.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-03-12T14:09:23.230" LastActivityDate="2014-03-12T14:09:23.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2030" PostTypeId="1" CreationDate="2014-03-03T10:08:17.333" Score="10" ViewCount="2965" Body="&lt;p&gt;Every time I travel on an airplane, the stewardess forces me to shut down my iPad.&#xA;I just lock it, and start using it again 5 minutes later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder why this is? Is it because I have to have my hands free if the airplane crashes? Or is there any other logical explanation?&lt;/p&gt;&#xA;" OwnerUserId="1056" LastEditorUserId="64" LastEditDate="2014-03-04T20:20:08.660" LastActivityDate="2014-03-04T20:20:08.660" Title="Why do I have to turn off my (non-cellular) iPad before takeoff?" Tags="&lt;safety&gt;&lt;passenger&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2031" PostTypeId="1" AcceptedAnswerId="2040" CreationDate="2014-03-03T10:33:09.187" Score="44" ViewCount="14559" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Tetraethyllead&quot;&gt;Lead in gasoline&lt;/a&gt; for automobiles has been banned from nearly every corner of the world, with most bans dating from the nineties. Why are we still poisoning ourselves with lead in Avgas? I understand that &lt;a href=&quot;http://en.wikipedia.org/wiki/Tetraethyllead&quot;&gt;Tetraethyllead&lt;/a&gt; (as it's apparently technically called) is an octane booster, but the Wikipedia article also mentions that advances in the production of high octane unleaded fuel have pretty much nullified that argument. There are more reasons of course, but none the automotive industry wasn't unable to overcome many decades ago. I know it's 'low-lead' with very little lead compared to 'traditional' gasoline, but the phase-out of leaded fuels in cars started back in the 1970s, so don't tell me that most aircraft are simply too old. Are aircraft engines so special compared to car engines, that they must get their &lt;a href=&quot;http://www.imdb.com/title/tt0133093/quotes?item=qt0324290&quot;&gt;fix of lead before they go flying&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also a fact that there are aircraft piston engines which do run perfectly fine on unleaded fuel, why is it that hardly any airport offers it? Even in cost-conscious and eco-friendly Europe, most airports offer only 100LL and Jet fuel.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2020-08-14T17:11:32.843" Title="Why are we still putting lead in our fuel?" Tags="&lt;fuel&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2032" PostTypeId="2" ParentId="389" CreationDate="2014-03-03T11:52:16.983" Score="9" Body="&lt;p&gt;As a simple anwer, no, it is not always required.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;ICAO Annex 6 4.3.4.3 Destination alternate aerodromes&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For a flight to be conducted in accordance with the instrument flight&#xA;rules, at least one destination alternate aerodrome shall be selected&#xA;and specified in the operational and ATS flight plans, unless:&lt;/p&gt;&#xA;&lt;p&gt;a) the&#xA;duration of the flight and the meteorological conditions prevailing&#xA;are such that there is reasonable certainty that, at the estimated&#xA;time of arrival at the aerodrome of intended landing, and for a&#xA;reasonable period before and after such time, the approach and landing&#xA;may be made under visual meteorological conditions; or&lt;/p&gt;&#xA;&lt;p&gt;b) the&#xA;aerodrome of intended landing is isolated and there is no suitable&#xA;destination alternate aerodrome.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also, there are similar descriptions for the requirements for take-off and en-route alternates.&lt;/p&gt;&#xA;&lt;p&gt;EASA adds aditional requirements in &lt;strong&gt;OPS 1.295&lt;/strong&gt; in the form of maximum flight time of 6 hours and at least two runways at the airport, but it is still allowed. I can only assume FAA does a similar thing&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-03T11:52:16.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2033" PostTypeId="2" ParentId="2030" CreationDate="2014-03-03T14:57:55.103" Score="3" Body="&lt;p&gt;Originally the regulations were introduced because electronic devices ALL transmit, especially those with antennas (and an iPad has 2-3 of those built in).&lt;br/&gt;&#xA;That forcing people to turn them off helps keep attention at the safety briefings helps a lot. Rather than having several hundred passengers playing minecraft, reading papers, watching videos, they now have less on their mind and might actually watch that safety briefing for a change.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And of course rather than argue with every passenger who claims &quot;but my device doesn't emit anything&quot; and having to have 10.000 page lists of what's allowed and what isn't by product numbers, far easier to just exclude everything.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-03T14:57:55.103" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2034" PostTypeId="2" ParentId="2031" CreationDate="2014-03-03T15:09:49.863" Score="2" Body="&lt;p&gt;One factor may well be that engines that run on leaded fuel are more fuel efficient than those that don't.&lt;br/&gt;&#xA;IOW you get more horsepower and/or better range from leaded fuel than from an identical amount of unleaded fuel when burnt in an engine with similar level of technology.&lt;br/&gt;&#xA;So an aircraft burning unleaded fuel would have worse performance and/or worse range. And of course especially the performance would cause trouble as it means longer takeoff run, lower service ceiling, worse climb performance, and potentially leaving you with an aircraft that can't even get off the ground.&lt;br/&gt;&#xA;And given the far longer lifespan of aviation engines as compared to car engines, there are far more aircraft around that need leaded fuel, the transition period would be far longer as well. And a car where you put a bottle of lead replacement compound in the fueltank, if it drives a bit slower it's not as bad as an aircraft where you're doing the same and it's not just slower, but can't climb to the same altitude and needs more runway...&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-03T15:09:49.863" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2035" PostTypeId="1" AcceptedAnswerId="2052" CreationDate="2014-03-03T15:34:23.090" Score="27" ViewCount="7066" Body="&lt;p&gt;I see that big planes (B737, A319 etc.) always need a staircase or a &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_bridge&quot;&gt;boarding tunnel&lt;/a&gt; in order for crew or passengers to enter the cabin since the position of the entry door is quite high (meters above the ground). What solutions are there if none of these options are available? (Except, obviously, for aircraft like DC-9's/MD-82 and 727's which had the rear entrance) How could the pilots get in? Is there some sort of manhole under the aircraft that can be opened to get inside with a sliding staircase or similar? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Living in Africa, I have been to a couple of airstrips where these aircraft do land. Obviously all the airports had stairs but since we cope with some strange situations over here, the question came into my mind. What is the alternative should something go wrong and no traditional means be available to get in the plane?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="65" LastEditDate="2015-03-12T15:50:15.803" LastActivityDate="2015-03-12T15:50:15.803" Title="How can one enter an airliner without stairs or a jet bridge?" Tags="&lt;airliner&gt;&lt;crew&gt;&lt;boarding&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2036" PostTypeId="1" AcceptedAnswerId="2037" CreationDate="2014-03-03T16:03:54.243" Score="12" ViewCount="6984" Body="&lt;p&gt;Pretty straightforward: what is the difference between &lt;em&gt;forward flight&lt;/em&gt;, &lt;em&gt;straight flight&lt;/em&gt;, &lt;em&gt;level flight&lt;/em&gt;, and &lt;em&gt;cruise flight&lt;/em&gt; in helicopters?&lt;/p&gt;&#xA;" OwnerUserId="1057" LastEditorUserId="774" LastEditDate="2014-03-03T22:30:14.920" LastActivityDate="2015-01-08T20:33:10.153" Title="What are Forward flight, Straight flight, Level flight, and Cruise flight in a helicopter?" Tags="&lt;helicopter&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2037" PostTypeId="2" ParentId="2036" CreationDate="2014-03-03T16:14:15.493" Score="8" Body="&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Helicopter_flight_controls#Forward_flight&quot; rel=&quot;nofollow&quot;&gt;Forward flight&lt;/a&gt;&lt;/strong&gt; is how the helicopter flies in most situations. It flies &lt;em&gt;similar&lt;/em&gt; to an airplane in this situation, with pitching up and down to increase and decrease airspeed. This is controlled by use of forward and aft cyclic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Straight flight&lt;/strong&gt; is where the tail rotor is set so that it opposes the turning tendency of the main rotor. This essentially prevents the helicopter from yawing while in flight. This is controlled by using the anti-torque pedals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Level flight&lt;/strong&gt; is simply when the helicopter is flying at a constant &lt;em&gt;altitude&lt;/em&gt;. This does not mean, however that its nose is pointed ahead, or that it is flying forward, merely that it is not gaining or losing altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure exactly what cruise flight is. When a helicopter is &quot;cruising&quot;, it most likely is maintaining altitude and flying straight ahead, but I don't think there is a separate term for it.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2015-01-04T23:17:24.770" LastActivityDate="2015-01-04T23:17:24.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2038" PostTypeId="2" ParentId="2035" CreationDate="2014-03-03T17:57:29.840" Score="16" Body="&lt;p&gt;There are no rear entrances these days, but many smaller jets like the Avro-RJ, Bombardier CRJ series or Embraer regional jets have their own air-stair on the main (front left) door. On the smaller planes the door are hinged at the bottom and the stair are part of the inner side of the door, on the larger ones there may be folding stairs stowed beside the door. B737 can have those too, but it's optional, so many operators choose not to have them (and on second-hand aircraft the operator sometimes bother removing them, but rarely adding them back). I've never heard of them on A320 family as it's a lot higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get always &lt;strong&gt;out&lt;/strong&gt; using the emergency slides and in cockpit they have a rope to climb down through the side window (where it's too high to jump from it) in case the cockpit door can't be used (happens sometimes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the only way &lt;strong&gt;in&lt;/strong&gt; is using &lt;strong&gt;stairs&lt;/strong&gt;. It's hard to imagine you wouldn't be able to scramble at least a &lt;strong&gt;ladder&lt;/strong&gt; even at very remote landing strip where the plane has made an emergency landing. Regular landing will obviously not be done to a place without regular stairs (unless the plane has integral airstairs, of course) and if it was emergency landing you need to bring in mechanics and fuel to get the plane out, brining a ladder is not much extra trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: As Kevin noted below, many aircraft have engineering access hatch in or behind nose wheel well. Not an option for boarding passengers, but the crew can use it when they don't have stairs/ladder handy.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-05-05T04:59:30.613" LastActivityDate="2014-05-05T04:59:30.613" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2039" PostTypeId="2" ParentId="2030" CreationDate="2014-03-03T18:13:54.020" Score="8" Body="&lt;p&gt;Actually, they don't!  Well, not always anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA recently issued a &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=15254&quot;&gt;press release&lt;/a&gt; titled &lt;strong&gt;FAA to Allow Airlines to Expand Use of Personal Electronics&lt;/strong&gt;.  This press release allows for the use of some electronics, including iPads and similar devices, during all phases of flight,.  However, it is up to each airline to change their procedures and to determine which devices can be safely used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a small excerpt from the press release:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passengers will eventually be able to read e-books, play games, and&#xA;  watch videos on their devices during all phases of flight, with very&#xA;  limited exceptions. Electronic items, books and magazines, must be&#xA;  held or put in the seat back pocket during the actual takeoff and&#xA;  landing roll. Cell phones should be in airplane mode or with cellular&#xA;  service disabled – i.e., no signal bars displayed—and cannot be used&#xA;  for voice communications based on FCC regulations that prohibit any&#xA;  airborne calls using cell phones.    If your air carrier provides&#xA;  Wi-Fi service during flight, you may use those services.  You can also&#xA;  continue to use short-range Bluetooth accessories, like wireless&#xA;  keyboards.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I flew on Jet Blue the day after that press release and they were already allowing iPads and similar devices as long as they were in airplane mode.  Other airlines will follow soon I'm sure, but their manuals and procedures must be updated and approved by the FAA first.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-03T18:13:54.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2040" PostTypeId="2" ParentId="2031" CreationDate="2014-03-03T18:17:12.683" Score="34" Body="&lt;p&gt;There is nothing &quot;special&quot; about an aircraft engine that requires lead in the fuel -- Engines don't much care about the lead in tetraethyl lead, nor do they much care &lt;em&gt;for&lt;/em&gt; it (it gets everywhere, fouling sparkplugs and contaminating the oil). What they care about is the octane (anti-knock) rating of the fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many &quot;low performance&quot; aircraft engines run just fine on unleaded fuels with a lower octane rating (among them the Lycoming O-320 and O-360 family that power a good chunk of the GA fleet), but high-performance aircraft engines (e.g. the IO-520 you'll find in Beech Bonanzas) require a 100 octane fuel. The approved specification for 100 octane aviation gasoline (&lt;a href=&quot;http://www.astm.org/Standards/D910.htm&quot;&gt;ASTM D910&lt;/a&gt;) lists tetraethyl lead as the octane booster of choice.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that some of the octane boosting techniques used in automotive gasoline are not acceptable for aircraft engines (the most common in the US being the addition of ethanol, which has two undesirable effects: reducing the energy content of the fuel, and damaging aviation fuel system seals and other components).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So why do we still make 100LL, and why don't we offer the other unleaded options at every airport?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation gasoline is a &lt;em&gt;minuscule&lt;/em&gt; slice of the gasoline market, so it doesn't make sense to have 5 tanks with 5 different grades of fuel at every airport:&lt;br&gt;&#xA;All aircraft engines will run on 100LL, so 100LL (leaded) aviation gasoline is still produced because it is a &quot;single fuel&quot; solution to piston aviation's needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If leaded avgas were to disappear tomorrow the engines that require it would be left without an approved fuel, which would result in those aircraft being grounded until such time as an alternative fuel could be developed or the engine manufacturers develop a procedure for derating the engines (operating them at reduced power). For obvious reasons neither of these options is attractive, particularly to folks who own higher-power engines which were presumably purchased for the performance...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing the avgas specification is quite a bit of work - it requires ensuring that the new fuel is a &quot;drop-in replacement&quot; for 100LL -- one which can be mixed with 100LL in any proportion, and will work correctly in any engine designed for 100LL fuel.&lt;br&gt;&#xA;&lt;a href=&quot;https://www.faa.gov/about/initiatives/avgas/&quot;&gt;The FAA is working with engine manufacturers and major fuel producers on a program which will result in such a specification&lt;/a&gt; (a Google search for &lt;code&gt;unleaded avgas transition&lt;/code&gt; also produces useful results), and hopefully a universal unleaded aviation fuel specification and one or more products will come out of those efforts.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-03T18:17:12.683" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2041" PostTypeId="2" ParentId="2035" CreationDate="2014-03-03T18:25:48.357" Score="13" Body="&lt;p&gt;Some large aircraft (like Air Force One) have been specially modified to include air stairs so that they don't have to rely on equipment on the ground:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://blogs.reuters.com/photographers-blog/files/2009/03/bvsmall.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zp2uQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air stairs are quite heavy though, so most airlines have made the business decision to remove them (to save money) and only operate out of airports that have appropriate ground facilities, including stairs.  If something happened and the stairs were not available on the ground, they would simply divert or reposition to an airport with adequate facilities.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-04T01:48:03.447" LastActivityDate="2014-03-04T01:48:03.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2042" PostTypeId="1" CreationDate="2014-03-03T19:34:27.873" Score="16" ViewCount="4658" Body="&lt;p&gt;Why do military aircraft have a lower landing gear than civilian? I have in mind the difference between a Lockheed C-130 Hercules and a Boeing or Airbus. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first possibility that jumps to mind is that one is more comfortable than the other, which is more robust. But would an aircraft designer reduce robustness to provide more comfort? &lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="1696" LastEditDate="2015-02-05T15:45:12.417" LastActivityDate="2015-02-05T15:45:12.417" Title="Why are military and civil aircraft landing gear generally so different?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;landing-gear&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2043" PostTypeId="2" ParentId="2035" CreationDate="2014-03-03T19:43:02.793" Score="13" Body="&lt;p&gt;In Canada's northern areas older large planes are used for freight.  The crew just bring along an aluminum ladder.&lt;/p&gt;&#xA;" OwnerUserId="1064" LastActivityDate="2014-03-03T19:43:02.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2044" PostTypeId="2" ParentId="2042" CreationDate="2014-03-03T19:45:30.693" Score="11" Body="&lt;p&gt;For the aircraft you use as examples the aircraft height above the ground (landing gear height) is mostly a function of use-case and clearances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the Boeing and Airbus airplanes you mention, the gear need be long to accommodate the engines hanging under the wings as well as the minimum bank angle needed to avoid wing strikes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the C-130 has the engines mounted up on a high wing and the aircraft needs to handle big slow heavy things like tanks being driven into the cargo.  The need of the tanks specifically probably mandates the interior floor be pretty close to the ground, or you might need extremely long ramps to for the tank to ascend (and these would pose their own problems).&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="774" LastEditDate="2014-03-03T22:33:03.583" LastActivityDate="2014-03-03T22:33:03.583" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2045" PostTypeId="1" CreationDate="2014-03-03T22:46:45.443" Score="15" ViewCount="2648" Body="&lt;p&gt;Through endless sources available it's possible to learn the rules of flying without undertaking formal training: I can take practice tests, study flying rules, laws, altitudes, speeds, controls, etc., however, I'd like to try out actually flying (preferably for free) before considering the option of paying for a full license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically I'd like to take a trial flight - I don't care if someone has to sit with me, but I'm not keen on the idea of spending a lot of money before at least having one flight under my belt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Teens often drive before getting licensed in private; any options for me to do the same with aircraft machines?&lt;/p&gt;&#xA;" OwnerUserId="1065" LastEditorUserId="64" LastEditDate="2014-03-04T04:29:59.507" LastActivityDate="2016-01-05T02:23:46.140" Title="Are there &quot;Introductory flights&quot; available to see if I want to pursue training?" Tags="&lt;flight-training&gt;" AnswerCount="8" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2046" PostTypeId="2" ParentId="2045" CreationDate="2014-03-03T23:03:29.807" Score="8" Body="&lt;p&gt;&lt;strong&gt;Training for Free&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very many if not all flight schools offer a &lt;strong&gt;scenic/tour/experience/introductory flight&lt;/strong&gt; in a general aviation aircraft such as a Cessna for the specific purpose of knowing if you want to seriously pick up flying, but I doubt you can convince them to do it for free - possibly they might give it at a discount when you sign up for a full course. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise there are many facilities nowadays which offer to test a full-scale simulator. Here again, it will cost a bit but you'll probably be a good deal of fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 'problem' is that aircraft are prohibitively expensive to ride on for free - you're often looking at $100+ an hour with an instructor, who you can't go without. In Europe, there's a good chance you're looking at €150 or so for the same, but these are just estimates. It's an awful lot more expensive than cars. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you're serious about spending several thousand dollars for a license, it won't hurt to get up a little before you commit yourself fully, and even paying the cost of a flight will be tiny if not insignificant compared to the future training cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Information Online&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I certainly agree with you that there's a lot of information online, but it doesn't substitute learning to understand the aircraft, and there's no substitute to the real world. The FAA says you need at least 40 hours of flying, along with a list of other requirements to get your license.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="938" LastEditDate="2016-01-05T02:23:46.140" LastActivityDate="2016-01-05T02:23:46.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2047" PostTypeId="2" ParentId="2045" CreationDate="2014-03-03T23:08:27.160" Score="13" Body="&lt;p&gt;Well, to put it bluntly, &lt;strong&gt;somebody&lt;/strong&gt; has to pay for the airplane.  Much like a car, somebody has to pay for the gas and maintenance.  The major difference is that &lt;strong&gt;both&lt;/strong&gt; cost a lot more on an airplane so it is a lot harder to get someone else to pay for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, similar to a car, if you have a friend that owns an airplane they may take you up for a ride and even (legally) let you fly it, but they remain the person in charge and responsible for the safe outcome of the flight.  If you want to try it &lt;strong&gt;for free&lt;/strong&gt; this is probably one of the only ways to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are willing to pay for a one-time flight which does not commit you to pay for your entire license, then you can go to almost any place that teaches people how to fly and they will be happy to let you fly with an instructor and charge you only for the time in the airplane and the time with the instructor.  Often they have an &quot;introductory&quot; flight just for this purpose which is discounted for potential students.  This is a relatively small cost in comparison to learning to fly that I highly recommend to anyone before they commit to getting their license. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="65" LastEditDate="2015-03-04T18:38:20.273" LastActivityDate="2015-03-04T18:38:20.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2048" PostTypeId="2" ParentId="2042" CreationDate="2014-03-03T23:24:06.707" Score="12" Body="&lt;p&gt;&lt;strong&gt;Easier to Load&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated earlier, this is your primary reason. You have to be able to load in cargo from the ground. If you want to get troops and vehicles in fast to somewhere with minimum equipment, you want to be able to roll them of the aircraft, and the lower the aircraft, the easier this is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Other considerations:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Shorter gear is stronger&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer you make the gear, the more it will bend. Bad news if you're trying to land on rough ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;More Cargo space&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shorter you make the gear, the less trouble you have finding space for it inside the aircraft, where you want to maximise the amount of space you have for cargo, especially for vehicles and the like. The anatomy of a cargo aircraft is that they are typically hollow inside, unlike passenger aircraft where they fold up into the center section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Landing gear is heavy&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing gear is very heavy, since its got to support the weight of the entire aircraft above. The shorter you make it- the lighter the aircraft gets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Better use of ground effect&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The low gear may bring the aircraft a little bit closer to the ground, maximising ground effect and lowering your landing speed, again very ideal for rough terrain.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note: These don't only apply to military aircraft, but to a lot of commericial ones as well, since the benefits are the same. Look at the Dash-8, ATR 42/72, BAe 146 along with the rear-engined planes, and they all try to do this for these reasons, although ease of cargo loading might not come first on the list.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-03T23:37:45.217" LastActivityDate="2014-03-03T23:37:45.217" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2049" PostTypeId="2" ParentId="2042" CreationDate="2014-03-04T00:08:43.493" Score="14" Body="&lt;p&gt;There is no difference between civil and military aircraft. Not the least because the civil and military transport aircraft &lt;em&gt;are actually the same models&lt;/em&gt;. Many military planes have civil variants like Lockheed C-130/&lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_L-100&quot;&gt;L-100&lt;/a&gt;, other military planes are derived from civil ones, e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/C-135&quot;&gt;C-135&lt;/a&gt; is B707.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference depends on where the wings and engines are placed. All the aircraft actually have similar clearance from the ground. Just on some the lowest point is fuselage, on others it's the engines hanging down from the wings and on propeller driven ones it is often the propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cargo planes (like C-130, C-5, An-124 or An-224) are often built with high wings, so the fuselage is lower and therefore easier to load. This is also concern for regional airliners as they are designed to carry their own stairs. That's why &lt;a href=&quot;http://en.wikipedia.org/wiki/BAE146&quot;&gt;BAe146&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/ATR-42&quot;&gt;ATR-42&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Dash-8&quot;&gt;Dash-8&lt;/a&gt; are high-wing and other like Bombardier &lt;a href=&quot;http://en.wikipedia.org/wiki/Bombardier_CRJ700&quot;&gt;CRJ series&lt;/a&gt; have tail-mounted engines so they can also be lower. On the other hand low or mid-wing designs with wing-mounted engines have better aerodynamic properties, which is why that construction prevails for large airlines.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-03-04T00:08:43.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2050" PostTypeId="2" ParentId="2035" CreationDate="2014-03-04T00:19:49.673" Score="16" Body="&lt;p&gt;At Cairo West, a joint Egyptian-US military airfield, we once used a fork-lift with an empty pallet to get military personnel on and off a 747-200 when the stairs weren't available. It took awhile. That was the method sometimes used to get JFK on Air Force One (when that airplane was a 707 and never in public view, although one picture got out) to avoid him exacerbating his back troubles by walking up the stairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, unless modified, 747-100s and -200s can be entered and exited from the ground if you're reasonably fit. At age 75 I could still do it, although I might groan a bit. We used that means on occasion, usually when the stairs had been pulled away, and we needed to get someone into the airplane and didn't want the delay of getting the stairs. Given these days of security concerns, I'm not comfortable with providing the details.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-03-04T05:59:17.010" LastActivityDate="2014-03-04T05:59:17.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2051" PostTypeId="2" ParentId="2025" CreationDate="2014-03-04T00:37:24.553" Score="0" Body="&lt;p&gt;Consider the following scenario: You're in a 747 close to touch down and you see another airplane taxi onto the runway. You're trimmed for landing, with the engines burning about 3,000 lbs per hour each, but now you go to go to max power to go around so you're going to give each engine around 20,000 lbs per hour (from old memory so don't quote). You're going to need a lot of trim change very quickly, and that need is going to continue while you clean up the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never heard of aileron trim on the yoke.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-03-04T00:37:24.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2052" PostTypeId="2" ParentId="2035" CreationDate="2014-03-04T03:57:07.353" Score="6" Body="&lt;p&gt;Very good answers but this image from @Qantas94Heavy comment link is self explanatory!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Snma8.jpg&quot; alt=&quot;Climbing into a 747&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2014-03-04T03:57:07.353" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2053" PostTypeId="2" ParentId="2045" CreationDate="2014-03-04T04:21:13.773" Score="6" Body="&lt;p&gt;As has been pointed out, most flight schools aren't going to take you up &quot;for free&quot; -- at a bare minimum they need to recoup the cost of fuel (right now somewhere between US\$50-70 for an hour in the air) and pay the instructor that goes up with you (flight instructors have this odd desire to eat food occasionally).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This usually boils down to about US\$100 to \$150 for a &quot;discovery flight&quot; (and at that price the school is often taking a small loss with the hope that you'll come back and train with them). It will probably be your cheapest flight lesson.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All is not lost however! There is one reasonably viable option to get a free flight: Meet a pilot and ask if you can tag along on their next trip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You don't say where you're located, but most general aviation airports have a pilot's association or flying club.  Visit your local airport and find out when they meet, show up, and introduce yourself.  If local pilots know you're interested in flying the good ones will usually go out out of their way to keep you interested, and if you're not sure about committing the time and money to obtain a license a trip with a local pilot where you actually &lt;em&gt;go somewhere&lt;/em&gt; is a great introduction (arguably better than the typical &quot;discovery flight&quot; where you go up, do some maneuvers, and go back to the airport you started at).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="72" LastEditDate="2014-04-23T12:41:37.400" LastActivityDate="2014-04-23T12:41:37.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2054" PostTypeId="1" AcceptedAnswerId="2057" CreationDate="2014-03-04T05:46:31.823" Score="38" ViewCount="9660" Body="&lt;p&gt;I was trying to explain to someone why the cabin is pressurized (no one wants hypoxia) and that led to discussion about the emergency oxygen masks available on airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a person didn't put on their oxygen mask, would they be able to survive the lack of oxygen while making an emergency descent to a safe altitude? Would they sustain severe brain injury?&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="97" LastEditDate="2014-09-17T00:15:46.913" LastActivityDate="2014-09-17T00:15:46.913" Title="Would failure to put on an oxygen mask during loss of cabin pressure result in death?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;passenger&gt;&lt;cabin-pressure&gt;&lt;hypoxia&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2055" PostTypeId="2" ParentId="2054" CreationDate="2014-03-04T06:13:45.067" Score="10" Body="&lt;p&gt;That would depend on at least the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;how high the cabin got during the process&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;how long it stayed high&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the physical condition of the passenger&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;perhaps to some degree how much oxygen was coming out of the masks of adjacent passengers&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I went through NASA's altitude chamber program at the Johnson Spaceflight Center back in the early 80s. They wouldn't take the chamber higher than 25,000 for civilians. I was in very good shape back then (hard to believe now) and stayed functional the longest, but when they finally told me to put my mask back on, they told me I only got it half way to my face. An instructor had to come over and assist me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did I suffer brain damage? Some might contend I did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seriously, I Googled &quot;survivability at high altitudes&quot; and saw lots of info.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-03-04T06:13:45.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2056" PostTypeId="2" ParentId="2054" CreationDate="2014-03-04T07:57:52.000" Score="14" Body="&lt;p&gt;Short answer? It's entirely possible that not putting on a mask could result in death.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Long answer:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The classic example of hypoxia is the &lt;a href=&quot;http://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash&quot;&gt;Payne Stewart Learjet crash&lt;/a&gt; that happened in 1999; the jet lost cabin pressure (and the crew lost consciousness) sometime in the 6 minutes between 23,000 feet and 36,500 feet. All 6 aboard perished in the crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the NTSB report, which the Wikipedia article quotes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Research has shown that a period of as little as 8 seconds without supplemental oxygen following rapid depressurization to about 30,000 feet (9,100 m) may cause a drop in oxygen saturation that can significantly impair cognitive functioning and increase the amount of time required to complete complex tasks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;http://en.wikipedia.org/wiki/Time_of_useful_consciousness&quot;&gt;tables available that show time of useful consciousness&lt;/a&gt;. Above FL300 (30,000 feet, or around 9,150m), a healthy human will have less than 3 minutes of useful consciousness. Prolonged hypoxia, at any altitude, can have serious repercussions. The National Institute of Health states that &quot;[some] brain cells start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause severe brain damage or death&quot; (&lt;a href=&quot;http://www.nlm.nih.gov/medlineplus/ency/article/001435.htm&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-03-04T07:57:52.000" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2057" PostTypeId="2" ParentId="2054" CreationDate="2014-03-04T08:02:37.583" Score="58" Body="&lt;h2&gt;I did high altitude training about three months ago, up to 30,000 feet simulated altitude.  Here's the timeline:&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Within 30 seconds (oximeter 100-95):&lt;/strong&gt; noticed physical symptoms beginning.  I could tell that something was wrong, but felt functional.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Within 60 seconds (oximeter ~90):&lt;/strong&gt; mild headache.  Still able to write my name.  Not feeling good, but acceptable.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Within 3 minutes (oximeter ~80):&lt;/strong&gt;  Able to do simple tasks when specifically directed (thread a nut onto a bolt), but completely unable to multitask at even the simplest things (tried to put my pen down...didn't notice that I missed the desk - it landed on the floor.)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Within ?? minutes (oximeter ~70):&lt;/strong&gt; I am no longer able to perceive the passage of time.  No longer able to take meaningful notes.  My signature is still legible - instinctive muscle memory apparently doesn't degrade nearly as fast.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Within 6 minutes (oximeter unknown):&lt;/strong&gt; I have taken another pen from my pocket and am playing &lt;a href=&quot;http://www.youtube.com/watch?v=lC1x0PJHPUQ&quot; rel=&quot;noreferrer&quot;&gt;the knife game from &amp;quot;Alien&amp;quot;&lt;/a&gt; with it.  This is much more interesting than paying attention to the directions from the instructors.  I don't notice anything odd about my behavior.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Immediately after:&lt;/strong&gt;  An instructor gives me a direct command to put my mask on.  I comply.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h2&gt;Total time in chamber: 7 minutes.  Time of useful consciousness in chamber: about 2 minutes&lt;/h2&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;So, to answer your question: &lt;strong&gt;It depends&lt;/strong&gt;.  I can safely say that seven minutes at 30,000 foot environment won't &lt;em&gt;guarantee&lt;/em&gt; death (because I've survived it), and it won't &lt;em&gt;guarantee&lt;/em&gt; severe brain injury (they let me keep flying) but on the other hand, I'm young and I exercise.  The best answer I can give is the same one that applies to &lt;a href=&quot;http://en.wikipedia.org/wiki/Scud_running&quot; rel=&quot;noreferrer&quot;&gt;scud running&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;h3&gt;Just because the guy before you was able to do it, doesn't mean you'll be able to do it.&lt;/h3&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-05T15:39:44.003" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2058" PostTypeId="1" AcceptedAnswerId="2063" CreationDate="2014-03-04T08:24:49.007" Score="12" ViewCount="2950" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/u9PMT.png&quot; alt=&quot;RNAV 25 KOEB&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say that we're directly west of &lt;code&gt;CATLI&lt;/code&gt; and have been cleared direct &lt;code&gt;CATLI&lt;/code&gt; for the RNAV approach.  We load the approach into the GNS430 and proceed direct the fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After crossing &lt;code&gt;CATLI&lt;/code&gt; outbound for the hold-in-lieu-of-procedure-turn, we realize that we want to stay in the hold for a few more turns.  &lt;strong&gt;How do I tell the 430 that I don't want it to sequence to &lt;code&gt;ZAMGI&lt;/code&gt; upon arrival at &lt;code&gt;CATLI&lt;/code&gt;?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="12720" LastEditDate="2016-03-21T09:53:47.027" LastActivityDate="2016-03-21T09:53:47.027" Title="How do I tell a Garmin 430 not to exit a hold?" Tags="&lt;navigation&gt;&lt;avionics&gt;&lt;instrument-procedures&gt;&lt;gnss&gt;&lt;gns430&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2059" PostTypeId="2" ParentId="1837" CreationDate="2014-03-04T11:37:42.673" Score="5" Body="&lt;p&gt;The question really boils down to: &quot;ATC clears me to fly an approach.  Is the approach clearance defined by what is on the approach plate, or is it specific to the type of navigation equipment used?&quot;  It turns out that it is based on the approach plate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is found here:&#xA;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;noreferrer&quot;&gt;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&lt;/a&gt;&#xA;Section 5-4-5.a.3(a)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;More than one navigational system separated by the word “or” indicates&#xA;  either type of equipment may be used to execute the final approach&#xA;  (e.g., VOR or GPS RWY 15).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When the chart is written as in your example, you are cleared for the approach, and you must use one of the approved types of navigational equipment to fly it.  There is no requirement in FAR/AIM to tell approach control which equipment you will be using (beyond the equipment code in your flight plan).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As further corroboration, section 5-4-7.d in the above document specifies that ATC is allowed to clear you for an approach even if the equipment required for some types of navigation systems is not available.  This actually is not that rare because NDB/GPS approaches are still used even if the NDB is not working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirement to notify ATC in the event of navigation radio failure is separate.  Oddly, you don't have to tell ATC if you have a glideslope receiver at all, but you are supposed to tell them if one that you do have breaks.  If it happened while you were actually flying the approach, I would encourage you to execute a missed approach.  But if you just want to fly an ILS/LOC approach as localizer-only for practice, ATC doesn't care and you don't need to tell them.&lt;/p&gt;&#xA;" OwnerUserId="1027" LastActivityDate="2014-03-04T11:37:42.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2060" PostTypeId="1" AcceptedAnswerId="2069" CreationDate="2014-03-04T16:13:41.243" Score="12" ViewCount="740" Body="&lt;p&gt;With the new Boeing 787 where Boeing has provided the capability to swap engine types if the aircraft goes to a new operator quite quickly, I'm wondering if there are any &lt;strong&gt;interchangeable flightdecks&lt;/strong&gt;? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say that you might have a legacy 737 for southwest, but an entirely different cockpit layout (containing the same capabilities) for a company which operates Boeing 787s as well, since the similarities would make training easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know a similar project was done on the DC-10s becoming MD-10s, as well as some Saudi MD-90s to be similar to MD-11, but both of these were long-time consuming projects. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I'm wondering if there are any aircraft which have this possibility and if not, why not? I'd see it as an opportunity to Boeing to have a 787 flightdeck shared with say the 777.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-04T16:18:53.497" LastActivityDate="2014-06-20T07:40:30.340" Title="Are there any aircraft that come with interchangeable flightdecks?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2061" PostTypeId="1" AcceptedAnswerId="2105" CreationDate="2014-03-04T17:10:16.350" Score="14" ViewCount="20775" Body="&lt;p&gt;Is there a legal definition of a &quot;cycle&quot; on a jet engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We must log the cycles, and some maintenance is determined by cycles.  From my understanding, this is partially because of the thermal dynamics of an engine cooling and then reheating, and partially because full takeoff power is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;usual&quot; time that you log a cycle is when an engine is started and the aircraft then takes off (using full rated takeoff power), but what about unusual situations like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine shutdown and restarted in flight&lt;/li&gt;&#xA;&lt;li&gt;Engine started, aircraft takes off, and then returns for a low pass or a touch and go:  Would this be two cycles (does it depend on the amount of power used during the touch and go?)?&lt;/li&gt;&#xA;&lt;li&gt;Engine started and then shut down without a flight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2017-08-28T07:05:45.647" Title="What defines a cycle on a jet engine?" Tags="&lt;faa-regulations&gt;&lt;jet-engine&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2062" PostTypeId="2" ParentId="2031" CreationDate="2014-03-04T17:23:05.443" Score="10" Body="&lt;p&gt;Lead in fuel is primarily an anti-knock agent, raising the octane rating and permitting higher compression ratios in the engine which in turn provides more power and more efficient use of fuel.  Many GA aircraft engines are built specifically to take advantage of the anti-knock, higher octane fuel.  Although there is a lot of work underway to develop a non-leaded substitute fuel that will allow the same performance, we are not there yet.  There is no alternative fuel certified for these engines, and burning unleaded fuel at high power settings will damage these engines severely and quickly.  So we still need the lead in these cases.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With luck and technology, this will change in a few years.  If not, diesel engines are a likely replacement for the 100LL burners.  But that is a pricey change for most GA planes.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-03-05T19:47:56.417" LastActivityDate="2014-03-05T19:47:56.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2063" PostTypeId="2" ParentId="2058" CreationDate="2014-03-04T18:34:54.987" Score="6" Body="&lt;p&gt;Press the OBS button to put waypoint sequencing into suspend, as indicated by the green &quot;SUSP&quot; appearing over the OBS button.&lt;/p&gt;&#xA;" OwnerUserId="577" LastActivityDate="2014-03-04T18:34:54.987" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2064" PostTypeId="2" ParentId="2054" CreationDate="2014-03-04T18:59:54.910" Score="9" Body="&lt;p&gt;The other answers focus on the physiology of failing to put a mask on, but I am going to offer another take on this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether you die from not putting on a mask depends on one thing: Did the pilots get their masks on before useful consciousness ran out?  If they did, you live.   If they didn't, you die.  It is as simple as that.  In the case the pilots get their masks on and no one else does, they will initiate an emergency descent.  This descent is typically initiated from memory items and not a checklist, so it can be initiated quickly.  The goal of the emergency descent is to be at 10,000 ft iASAP (for us the goal was under 4 minutes), and many jet aircraft can get there faster.  The only regulations I am aware of regarding the descent is that you must be below 25,000 ft in under 2 minutes (25.841; assuming complete loss of cabin).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the emergency descent is initiated and in all likelyhood it won't matter if you put the mask on or not, you'll wake up during the descent and it'll only have been a few minutes.  Its always better to put the mask on, but it won't be the deciding factor, the pilots masks will be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll also point out the O2 masks the pilots have are vastly different than those the passengers get.  Pax get chemical O2 generators that last about 15 minutes once activated (by pulling the tubing down) and attatch with a flimsy rubber band.  The pilots get quick-don masks fed by an O2 cylinder.  To don the masks you simply grab it, the O2 pressure inflates the webbing around the mask. Then you slip it on your head, let go of it and the mask compresses around your face.  Twist the mask regulator to Emergency and you have positive pressure forced flow O2 for the descent.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§25.841   Pressurized cabins.&#xA;  (a) Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet at the maximum operating altitude of the airplane under normal operating conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The airplane must be designed so that occupants will not be exposed to a cabin pressure altitude that exceeds the following after decompression from any failure condition not shown to be extremely improbable:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Twenty-five thousand (25,000) feet for more than 2 minutes; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Forty thousand (40,000) feet for any duration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-05T04:15:04.543" LastActivityDate="2014-03-05T04:15:04.543" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2065" PostTypeId="1" CreationDate="2014-03-04T19:01:18.960" Score="23" ViewCount="54398" Body="&lt;p&gt;Is there a difference between a balked landing and a go-around?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is, what exactly is a balked landing?&lt;/p&gt;&#xA;" OwnerUserId="1076" LastEditorUserId="62" LastEditDate="2020-06-15T14:26:57.657" LastActivityDate="2020-06-15T14:26:57.657" Title="What's the difference between a balked landing and a go-around?" Tags="&lt;landing&gt;&lt;terminology&gt;&lt;go-around&gt;" AnswerCount="10" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2066" PostTypeId="2" ParentId="2065" CreationDate="2014-03-04T19:14:07.107" Score="9" Body="&lt;p&gt;Almost everything I read says that a balked landing is the same thing as a go-around. (Indeed, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Balked_landing&quot; rel=&quot;noreferrer&quot;&gt;wikipedia page&lt;/a&gt; for &lt;em&gt;balked landing&lt;/em&gt; redirects to the 'go-around' page).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In these cases, a balked landing, also known as a go-around, creates a better opportunity for a near perfect landing [&lt;a href=&quot;http://www.jetcharters.com/blog/2013/03/balked-landing-a-rare-but-valuable-procedure-for-a-safer-landing.html&quot; rel=&quot;noreferrer&quot;&gt;src&lt;/a&gt;]&lt;/p&gt;&#xA;&lt;p&gt;A balked landing – also known as a go-around, is an aborted landing of an aircraft that is on final approach … for landing [&lt;a href=&quot;http://www.mountainaviation.com/2011/09/20/balked-landings-at-mountain-airports/&quot; rel=&quot;noreferrer&quot;&gt;src&lt;/a&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.pprune.org/archive/index.php/t-368369.html&quot; rel=&quot;noreferrer&quot;&gt;This thread&lt;/a&gt; mentions that they are the same as a go-around, but can include when the wheels &lt;em&gt;briefly&lt;/em&gt; touch down.&lt;/p&gt;&#xA;&lt;p&gt;However, I did find one &lt;em&gt;slightly&lt;/em&gt; dissenting opinion &lt;a href=&quot;http://macsblog.com/2012/04/balked-landing-worth-the-practice/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;I don’t know of an official definition of a balked landing that makes it different from a go-around. The way the balked landing term is generally used is that the actual landing procedure has begun and must be aborted. A go-around generally begins at a higher altitude and lacks the urgency of the balked landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, in summary, they're pretty much the same thing (or exactly the same thing), but some people differentiate the two by the &lt;em&gt;altitude&lt;/em&gt; the procedure begins at.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-04T19:14:07.107" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2067" PostTypeId="2" ParentId="2065" CreationDate="2014-03-04T20:28:35.943" Score="14" Body="&lt;p&gt;The only term in the Pilot Controller Glossary is Go Around, so should technically be the only term used, at least when communicating with ATC:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/G.HTM&quot;&gt;&lt;strong&gt;GO AROUND-&lt;/strong&gt;&lt;/a&gt; Instructions for a pilot to abandon his/her approach to landing. Additional instructions may follow. Unless otherwise advised&#xA;  by ATC, a VFR aircraft or an aircraft conducting visual approach&#xA;  should overfly the runway while climbing to traffic pattern altitude&#xA;  and enter the traffic pattern via the crosswind leg. A pilot on an IFR&#xA;  flight plan making an instrument approach should execute the published&#xA;  missed approach procedure or proceed as instructed by ATC; e.g., &quot;Go&#xA;  around&quot; (additional instructions if required).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(See LOW APPROACH.)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(See MISSED APPROACH.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-5F.pdf&quot;&gt;ATP PTS&lt;/a&gt; also includes a Rejected Landing, which is what our simulator instructors refer to as a Balked Landing, and must be at or below 50 feet AGL.  It has the following note describing it in the PTS:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;NOTE:&lt;/strong&gt; The maneuver may be combined with instrument, circling,  or missed approach procedures, but instrument conditions  need not be&#xA;  simulated below 100 feet above the runway.  This maneuver should be&#xA;  initiated approximately 50 feet  above the runway or landing area and&#xA;  approximately over  the runway threshold or as recommended by the FSB &#xA;  Report.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilot follows the same procedures for both of them by aborting the landing, cleaning up the airplane, and flying the appropriate procedure afterwards.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-04T20:28:35.943" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2068" PostTypeId="2" ParentId="1854" CreationDate="2014-03-04T20:50:02.387" Score="13" Body="&lt;p&gt;OK, I did a little digging and here's what I can definitively tell you:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1-866-GA-SECURE&lt;/strong&gt; is a joint venture between AOPA's &quot;Airport Watch&quot; program and the TSA.&lt;br&gt;&#xA;The hotline is staffed by federal officials and can be used for reporting suspicious or unauthorized activity - e.g. the theft of an aircraft, someone prowling around on the ramp after hours, etc.&lt;br&gt;&#xA;The folks answering the hotline will be able to contact local law enforcement (and being that they're federal officers making the call instead of Joe Pilot, they &lt;em&gt;may&lt;/em&gt; get a quicker response than you would), but police dispatch isn't their primary function.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/security_guidelines_for_general_aviation_airports.pdf&quot;&gt;The TSA's own guidance&lt;/a&gt; on this hotline indicates that it shouldn't be your first resort -- they would prefer that you contact:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Airport management/operations/FBOs&lt;/strong&gt;&lt;br&gt;&#xA;Particularly at fields that are attended 24/7, and those with security or police presence, calling the folks &lt;em&gt;on the field&lt;/em&gt; will often give the fastest response, and they should be your first call.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The TSA Hotline (1-866-GA-SECURE)&lt;/strong&gt;&lt;br&gt;&#xA;For fields which are not attended / don't have a security or police presence, this can be an effective way of getting law enforcement to the field quickly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;911 or other local law enforcement emergency numbers&lt;/strong&gt;&lt;br&gt;&#xA;In situations with immediate and potentially dangerous consequences, or ongoing criminal activity (breaking into aircraft, bypassing gate locks, etc.) calling local law enforcement's emergency number / 911 is The Right Thing To Do.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In all cases you can follow up with a call to the TSA hotline to confirm they're aware of the incident.  Whether on an initial call with an ongoing situation or a follow-up the hotline folks will want the basic 911 information (Who you are, Where you are, and What your emergency/situation is). Obviously depending on the situation they may ask for additional details - e.g. if you're reporting that a plane was stolen it would be very helpful if you could provide the registration number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flash.aopa.org/asf/gasecurity/gasecurity.cfm&quot;&gt;AOPA's GA Security course&lt;/a&gt; covers a bit more of what you may be asked for / about, and the kind of things you should be looking for when informing any of the above authorities of suspicious activity.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Who responds to your hotline call and how quickly they respond is less definitive: It will vary depending on where you are and the local resources available.  A grass strip many miles away from the closest police presence at 3 AM will obviously have a longer response time than a 24x7 attended field with a police presence on the field, no matter who you call.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically the first response will be airport personnel (if the field is attended) or local law enforcement (and obviously that will be the case if you're calling the airport's management/operations office or the local police directly).  Whether or not federal authorities get involved in the response would likely depend on what you're reporting.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-04T20:50:02.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2069" PostTypeId="2" ParentId="2060" CreationDate="2014-03-04T21:46:42.557" Score="8" Body="&lt;p&gt;According to &lt;a href=&quot;https://aviation.stackexchange.com/a/1521/524&quot;&gt;this answer&lt;/a&gt; they used to be very customizable, but not very much interchangeable at least to the point that no one bothered to change them on second-hand aircraft. They are reducing it because it only causes confusion. Aircraft change owners and pilots change employers and it's most useful if all aircraft of the same type have the same cockpit layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as 787 goes, it has very similar flight deck to 777, always, to the point it has &lt;a href=&quot;http://fsims.faa.gov/wdocs/fsb/b-787_fsb.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;common type rating&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-03-04T21:46:42.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2070" PostTypeId="1" AcceptedAnswerId="2075" CreationDate="2014-03-05T08:23:30.627" Score="20" ViewCount="3652" Body="&lt;p&gt;I know there are airports with more than one ATC Tower, though I only know it from my own country (SCHIPHOL - EHAM). This airport has two towers called Tower-Center and Tower-West. Tower-West is built because of a sixth runway (18R - 36L), that wasn't clearly visible from Tower-Center. (They found this out after completion of the sixth runway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How common is it an airport decides to built a second tower, and are there a certain rules or limitations before the decision can be made?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next to that; what are the practical consequences for pilots and ATC's? Do they not only switch between startup- and ground-controllers but also between several ground controllers?&lt;/p&gt;&#xA;" OwnerUserId="432" LastEditorUserId="1696" LastEditDate="2015-02-14T21:20:01.403" LastActivityDate="2016-08-20T08:43:31.060" Title="How does having multiple ATC towers affect airport operations?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2071" PostTypeId="2" ParentId="2065" CreationDate="2014-03-05T10:10:00.983" Score="6" Body="&lt;p&gt;While there is no distinction between balked landing &amp;lt;-&gt; go arround, &quot;technically&quot; you will find in regulations a difference between &lt;strong&gt;balked landing&lt;/strong&gt; and &lt;strong&gt;missed approach&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Missed Approach&lt;/strong&gt; climb is defined as a go-around from at or above DH (possibly with one engine inoperative). CS(Part) 25 assumes required gradient on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Go-around thrust on remaining engines  &lt;/li&gt;&#xA;&lt;li&gt;Landing gear retracted &lt;/li&gt;&#xA;&lt;li&gt;Approach flap set&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Balked Landing&lt;/strong&gt; climb is a go-around from below DH, possibly in the flare (note that all engines are assumed available). CS (Part) 25 assumes required gradient on :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Go-around thrust all engines &lt;/li&gt;&#xA;&lt;li&gt;Landing gear down &lt;/li&gt;&#xA;&lt;li&gt;Landing flap set &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-03-05T10:10:00.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2072" PostTypeId="1" CreationDate="2014-03-05T13:47:27.880" Score="16" ViewCount="10808" Body="&lt;p&gt;On a recent flight the captain made an announcement at the gate that they need to reboot the computer as somethings aren't working, and rebooting &lt;em&gt;usually&lt;/em&gt; solves the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After posting this on twitter I got a replying saying that most planes have 3 computers and rebooting during flight is common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the reasons for reboot? For me it sounds like a software/computer that isn't tested thoroughly instead.&lt;/p&gt;&#xA;" OwnerUserId="1082" LastEditorUserId="64" LastEditDate="2014-03-05T19:04:46.270" LastActivityDate="2018-01-18T17:01:11.637" Title="Is rebooting the computer normal before/during flights?" Tags="&lt;cockpit&gt;" AnswerCount="4" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2073" PostTypeId="2" ParentId="2072" CreationDate="2014-03-05T15:48:53.907" Score="19" Body="&lt;p&gt;Today's modern airplanes have &lt;strong&gt;many&lt;/strong&gt; computers, and sometimes things get out of sync and don't communicate properly.  During the preflight checks, we check each system according to the recommendations of the manufacturer, and occasionally one of the checks will not pass correctly.  Depending on the system, when a check fails, rebooting the computer may be an option to see if it fixes it (similar to rebooting your home computer).  Other times, the issue is the communication protocol between two (or more) different computers.  Often times in this case, the entire airplane must be powered down in order to reset them all at the same time.  Since these tests aren't performed in the air, the problem usually doesn't crop up there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the vast majority of cases it isn't a safety critical item that we are dealing with (where the software testing is more thorough), but rather a monitoring system.  The safety critical items (like flight control software, etc.) will have multiple redundant systems and often have different versions of software on at least one of the computers &quot;just in case&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally the flight crew won't tell the passengers when they need to &quot;reboot&quot; a computer unless we have to power down the entire airplane.  That's very noticeable and will cause some people to worry so we like to give you a heads up before all of the lights go out and the air conditioning system shuts down.  That of course is up to the discretion of the flight crew though.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-06T17:46:54.083" LastActivityDate="2014-03-06T17:46:54.083" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2074" PostTypeId="2" ParentId="2072" CreationDate="2014-03-05T15:51:09.153" Score="6" Body="&lt;p&gt;Airliners are more complex, so I suppose it's possible.  On light aircraft, I've never heard of anyone having to reboot the computer (glass panel systems).  Sometimes we have to reboot our radios, and I've had to reboot FADEC (engine control) computers before though.&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-03-05T15:51:09.153" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2075" PostTypeId="2" ParentId="2070" CreationDate="2014-03-05T15:54:33.430" Score="16" Body="&lt;p&gt;At larger airports it is fairly common to have more than one tower, but it all comes down to how well the tower controllers can see airplanes.  Sometimes they have different towers for ground control frequencies and tower control frequencies, and the position of the tower is optimized for the appropriate task.  For very large airports, they may need towers in different areas of the airport to properly see airplanes at each runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as practical consequences it doesn't matter much whether they have one or more towers.  At very busy airports they split up the tower/ground controllers/frequencies because one person can only control so many airplanes at a time.  For instance, there may be one controller for the North runway and one for the South runway.  In this case, there could be only one ground controller, or there may be two or even more, depending on the complexity of the ground operations.  With multiple ground frequencies, if you need to taxi from one controlled area to another, the controller that you are talking to will tell you to hold short of a particular point and contact ground on the other frequency.  Once you contact the second controller, they will clear you to continue taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, it is very specific to the local conditions, and they do what they have to in order to properly control the traffic.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-05T15:54:33.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2076" PostTypeId="2" ParentId="2072" CreationDate="2014-03-05T16:06:07.780" Score="11" Body="&lt;p&gt;This was probably the captain trying to be funny and use relatable terms for what was going on.  In the EMB-145 occasionally the ACARS would stop working and you could re-initialize that during flight.  The actual computer systems, however, could be reset but this is something you'd only do on the ground as it either involved powering down the aircraft or getting MX out to open some panels and pull breakers / flip switches. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The few things that could be reset in the air by pulling and resetting a breaker were things like FMS, ACARS and the autopilot, which we would do when directed by the QRH or MX and perhaps this is what the captain was referring to.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-05T16:06:07.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2077" PostTypeId="1" AcceptedAnswerId="33196" CreationDate="2014-03-05T23:02:26.240" Score="13" ViewCount="2080" Body="&lt;p&gt;Is a checkride which is required in order to qualify a pilot for 121 or 135 operations itself conducted under Part 91 or Part 121/135 rules?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, is a first class medical required in order to be PIC for the line check required by 135.299 or is only a second class medical required?  Is a fully qualified 121/135 SIC required in order to do the flight (in non-revenue service), or could it be done with an SIC qualified only for Part 91 flights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that in order to &lt;strong&gt;act&lt;/strong&gt; as PIC of a Part 121/135 flight you need those, but what about for the actual checkride?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-11-10T16:36:39.913" LastActivityDate="2016-11-17T19:54:20.020" Title="Is an FAA Part 121/135 checkride conducted under Part 91 or Part 121/135?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;far-135&gt;&lt;far-91&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2078" PostTypeId="1" AcceptedAnswerId="2081" CreationDate="2014-03-06T03:55:22.593" Score="239" ViewCount="148219" Body="&lt;p&gt;On most A-10s I have seen, the area under the cockpit is darker than the rest of the plane. Is there a reason for this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Q2HT.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="3386" LastEditDate="2017-06-05T17:09:52.497" LastActivityDate="2017-06-05T17:09:52.497" Title="What is the dark spot visible below the cockpit on A-10s?" Tags="&lt;military&gt;&lt;feature-identification&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="35" ContentLicense="CC BY-SA 3.0" />
  <row Id="2079" PostTypeId="2" ParentId="2031" CreationDate="2014-03-06T04:20:04.763" Score="2" Body="&lt;p&gt;My understanding is that it is simply a case of certification.  There is no replacement certified fuel that will take the place of 100LL.&lt;/p&gt;&#xA;" OwnerUserId="793" LastActivityDate="2014-03-06T04:20:04.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2080" PostTypeId="1" CreationDate="2014-03-06T04:37:27.610" Score="4" ViewCount="1580" Body="&lt;p&gt;Aircraft certification is covered by 14 CFR 23 and 25, what parts cover aircraft engines?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-06T07:05:43.660" Title="Which FAA regulations cover the certification of aircraft engines?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2081" PostTypeId="2" ParentId="2078" CreationDate="2014-03-06T04:59:31.470" Score="310" Body="&lt;p&gt;It's a false cockpit, a type of camouflage &lt;a href=&quot;http://www.google.com/patents/US4448371&quot;&gt;patented in 1980&lt;/a&gt; by Keith Ferris, a US artist and camouflage designer. From some angles, it makes it difficult to determine the orientation of the aircraft. The Canadians were the first to apply it; pictured is a CF-18 Hornet with one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kls6Jm.jpg&quot; alt=&quot;Canadian CF-18 Hornet, inverted, with false canopy.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice how at a glance, it takes a second to realize the Hornet is inverted and pulling towards the ground. During dogfights this can be enough to make opposing pilots think the aircraft is going a different direction. It might not seem like much in a photo, or if you're watching an aircraft fly past at an air show or airport. In the stress of combat while pulling extra Gs it's more than enough to confuse or delay a reaction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the air to ground mission, this is particularly important. If an A-10 encountered antiaircraft fire or an enemy aircraft it would have to rely on its own agility to escape or gain the upper hand. Other nations have adopted this technique — I've seen French and Russian types, and possibly Gripens of some air force. As far as I know, the A-10 is the only US aircraft regularly camouflaged in this way.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-06T23:43:49.537" LastActivityDate="2014-03-06T23:43:49.537" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2082" PostTypeId="2" ParentId="2080" CreationDate="2014-03-06T07:05:43.660" Score="2" Body="&lt;p&gt;The relevant section of the FARs for engine certification standards is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr33_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;14CFR33 - AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES&lt;/a&gt;, with 33.31 through 33.57 dealing with reciprocating (piston) powerplants &amp;amp; their testing requirements, and 33.61 through 33.99 being the equivalent for turbine powerplants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also the &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.list/parentTopicID/109&quot; rel=&quot;nofollow&quot;&gt;33 series Advisory Circulars&lt;/a&gt; dealing with such fun topics as how to comply with the &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99690&quot; rel=&quot;nofollow&quot;&gt;Bird Ingestion Certification Standards (33.76-1A)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-06T07:05:43.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2083" PostTypeId="1" CreationDate="2014-03-06T11:54:46.547" Score="7" ViewCount="2756" Body="&lt;p&gt;Following acceleration parameters are transmitted from Inertial Reference System (IRS) to Flight Control System (FCS):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight Path Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Along Track Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Cross Track Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Vertical Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Unbiased Normal Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Along Heading Acceleration&lt;/li&gt;&#xA;&lt;li&gt;Cross Heading Acceleration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I only know acceleration based on the aircraft axis i.e lateral, longitudinal &amp;amp; Normal acceleration but what these acceleration parameters signifies?&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="1696" LastEditDate="2015-04-21T16:12:51.887" LastActivityDate="2015-04-21T16:12:51.887" Title="What are these acceleration parameters produced by the Inertial Reference System?" Tags="&lt;flight-controls&gt;&lt;measurement&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2085" PostTypeId="2" ParentId="1839" CreationDate="2014-03-06T16:09:54.250" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.geaviation.com/&quot; rel=&quot;nofollow&quot;&gt;GE Aviation&lt;/a&gt; develops some avionics in addition to engines and other systems.&lt;/p&gt;&#xA;" OwnerUserId="1113" LastActivityDate="2014-03-06T16:09:54.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2086" PostTypeId="2" ParentId="1539" CreationDate="2014-03-06T16:41:48.880" Score="5" Body="&lt;p&gt;Airport ground charts are always part of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeronautical_Information_Publication&quot; rel=&quot;nofollow&quot;&gt;AIP&lt;/a&gt; (Airport Information Publication). They are usually publicly available in electronic format, but not always easy to find. Wikipedia's entry for AIP has a &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For european airports, you can get them from &lt;a href=&quot;http://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol&lt;/a&gt; (requires registration).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you can also usually get these directly from the country's CAA or AIS. Here's the ones you asked for (be aware these links may only work for a short period of time):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/aip/enligne/FRANCE/NON%20AIRAC-2015-04-02/html/eAIP/Cartes/MIA/LFPG/AD%202%20LFPG%20OACI%2001.pdf&quot; rel=&quot;nofollow&quot;&gt;Paris CDG&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ais-netherlands.nl/aim/2015-02-19-AIRAC/eAIP/html/graphics/eAIP/EH-AD-2.EHAM-ADC-A2s.pdf&quot; rel=&quot;nofollow&quot;&gt;Amsterdam Schiphol&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://lis.rlp.cz/ais_data/aip/data/valid/a2-pr-adc.pdf&quot; rel=&quot;nofollow&quot;&gt;Prague&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1128" LastEditorUserId="1128" LastEditDate="2015-04-11T11:34:01.390" LastActivityDate="2015-04-11T11:34:01.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2087" PostTypeId="2" ParentId="2070" CreationDate="2014-03-06T17:06:50.320" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How common is it an airport decides to built a second tower, and are there a certain rules or limitations before the decision can be made?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's fairly common where there's more than one runway, and it has a lot to do with visibility from the ATC Tower cab. Under optimal conditions, ATC would need to be able to see all airfield paved areas with a minimum Line of Sight angle which varies from regulator to regulator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can sometimes prove difficult for runway thresholds if their elevation and distance to the tower location make this angle too low. Big terminal buildings (or any other building for that matter) can also be an obstacle to visibility, especially on apron areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The decision to go for more than one tower, from an operational point of view, comes down basically to the need to have control of all airfield areas. Building an additional control tower is not only very costly, but also adds complexity to ground operations which is always an undesirable (albeit inevitable) effect. In some airports apron control is transferred not to another tower, but to follow me personnel under the supervision of ATC, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the practical consequences for pilots and ATC, Lnafziger has done a better job answering your question than I could have hoped to achieve.&lt;/p&gt;&#xA;" OwnerUserId="1128" LastEditorUserId="1128" LastEditDate="2014-03-06T19:23:27.337" LastActivityDate="2014-03-06T19:23:27.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2088" PostTypeId="2" ParentId="2078" CreationDate="2014-03-06T18:03:27.037" Score="24" Body="&lt;p&gt;There was an article on this in &lt;em&gt;Aerospace&lt;/em&gt; magazine way back in the late 1980s (I still have a photocopy somewhere).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They called it Visual Stealth. The article included the long history, including&#xA;using lights to illuminate the darker regions of aircraft when viewed from the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One picture I saw clearly showed a 'tail shadow' painted on the bottom&#xA;of an F16. False cockpits were common, as were painting the tops and bottoms &#xA;different colors. Ground Strike aircraft would commonly have yellows and &#xA;brown camouflage, white in the winter (Germany). The Navy was using blues and&#xA;grays, with the tail squadron markings rather dull.  &lt;/p&gt;&#xA;" OwnerUserId="1162" LastEditorUserId="5" LastEditDate="2014-03-06T18:38:49.700" LastActivityDate="2014-03-06T18:38:49.700" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2089" PostTypeId="2" ParentId="2019" CreationDate="2014-03-06T19:15:59.737" Score="8" Body="&lt;p&gt;A lot has changed since the Frank Abagnale / &quot;Catch Me If You Can&quot; days, and riding as a non-revenue passenger (particularly in the cockpit jump seat) is no longer not as simple as grabbing a passable captain's uniform, polishing your shoes up, and smooth-talking the flight crew.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone seeking a ride in an airplane jump seat would still have to pass through airport security and prove their identity &amp;amp; authorization to occupy such a seat to the satisfaction of the crew operating the flight, which would likely include checking credentials that are at lease somewhat difficult to forge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in short it's &lt;strong&gt;&lt;em&gt;possible&lt;/em&gt;&lt;/strong&gt; – if someone is particularly adept at &lt;a href=&quot;http://en.wikipedia.org/wiki/Social_engineering_%28security%29&quot;&gt;social engineering&lt;/a&gt;, forgery, and has at least a working knowledge of airport &amp;amp; airline security procedures they &lt;em&gt;might&lt;/em&gt; get away with it – but it's &lt;strong&gt;&lt;em&gt;extremely unlikely&lt;/em&gt;&lt;/strong&gt;, and as has been pointed out the consequences if and when you get caught are particularly unpleasant these days.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-06T19:15:59.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2090" PostTypeId="1" CreationDate="2014-03-06T21:02:53.127" Score="22" ViewCount="3138" Body="&lt;p&gt;We would never consider putting an infant or toddler into a car without a carseat, but we don't hesitate to do exactly this when getting onto a large airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you aren't aware of the concept of a lap child, this is a child, typically under 2 years of age, who can board an airplane without an assigned seat and must be held by a parent/guardian for the duration of the flight (including the takeoff and landing). The only safety consideration is that the lap child must be seated in a row with adequate O&lt;sub&gt;2&lt;/sub&gt; masks in case of depressurization (some rows have more masks than seats). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have always considered this to be an unsafe practice, but have never had data to back that up. It seems to me that holding on to a 20 lbs child when subject to strong turbulence or unexpected maneuvering would be difficult. While not common, adults are occasionally severely injured in these events but I've never noted a lap child being hurt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;Does anyone know of instances where a lap child was injured during a flight?&lt;/b&gt; I'm not interested in instances where everyone is hurt but rather instances that having been secured in a car seat would reasonably have prevented the injury.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="65" LastEditDate="2015-02-27T15:17:12.703" LastActivityDate="2018-05-05T09:50:49.513" Title="Are children safe when seated in lap during a flight?" Tags="&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2091" PostTypeId="2" ParentId="2090" CreationDate="2014-03-06T23:29:28.673" Score="28" Body="&lt;p&gt;Your instincts are correct, or at least the NTSB agrees with you - they don't like the idea of &quot;Lap Children&quot; on aircraft, &lt;a href=&quot;http://www.ntsb.gov/doclib/safetyalerts/SA_015.pdf&quot;&gt;and they've come out and said as much in this Safety Alert&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They reiterated that position again in &lt;a href=&quot;http://www.ntsb.gov/doclib/recletters/2010/A-10-121-123.pdf&quot;&gt;a 2010 letter to the FAA&lt;/a&gt; which includes a number of incidents from NTSB investiations, including:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;… on July 19, 1989, United Airlines flight 232 crashed during an attempted emergency landing at Sioux City, Iowa, after the fragmentation and separation of an engine fan disk. Of the 296 airplane occupants, 111 were killed, 47 received serious injuries, 125 received minor injuries, and 13 were not injured. Four children, ages 11 to 26 months,17 were aboard the airplane and were being held by adults. A 23-month-old child was killed, and the other three children received minor injuries. The parents of the four lap-held children were instructed to place their children on the cabin floor and hold them in that position while the adults assumed the protective brace position. After the accident, three of the parents reported that they were unable to hold onto their children during the accident sequence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;… USAir flight 1016 in Charlotte, North Carolina. The flight crew decided to continue an approach into severe convective activity and was executing a missed approach when the airplane collided with trees and a private residence near the airport. Of the 57 airplane occupants, 37 were killed, 16 received serious injuries, and 4 received minor injuries. Among those occupants who were killed was a 9-month-old child who was held by her mother on her lap. The child’s mother survived the accident but was unable to hold onto her child during the impact sequence, and the child struck several seats. The NTSB believed that the child might not have sustained fatal injuries if she had been properly restrained in a child restraint system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Granted both of these were pretty severe accidents, but the NTSB investigators found that the lack of restraints was potentially a major contributing factor to the injuries of children on these flights.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In that same letter the NTSB also notes that unrestrained children are not just a hazard to themselves in a crash:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passengers are required to securely stow all carry-on baggage during takeoff and landing because of the potential risk of injury to other passengers in the event of an unexpected hazardous encounter. However, passengers are permitted to hold a child of equal size and weight in their lap. When children under 2 years of age are not required to be restrained for their own safety, the safety of their fellow passengers also becomes an issue.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/safety/children.html&quot;&gt;See here for more NTSB pronouncements on the subject of child safety in transportation.&lt;/a&gt;&lt;br&gt;&#xA;They even have some excellent videos and simulations showing restrained versus unrestrained children.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-06T23:44:22.457" LastActivityDate="2014-03-06T23:44:22.457" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2092" PostTypeId="2" ParentId="2061" CreationDate="2014-03-07T01:50:09.583" Score="8" Body="&lt;p&gt;A cycle is a start to a shutdown.  Lets say there is a flight that is loaded with pax, bags, and fuel.  They push back and start both engines since the weather is good and their at an outstation.  As they taxi to the departure runway, BAM, ground calls up saying there is a groundstop for the hub and its going to be about 30 minutes.  The flight pulls into some empty ramps space, and shuts down both engines.  Groundstop lifts, both engines started again, and the flight departs.  After landing, pulling into the gate, and shutting down the engines, we can say that for this flight, each engine went through two cycles.  ALL of this info is logged and maintenance can access it.  With some of the newer engines and higher service packages, OEM&lt;/p&gt;&#xA;" OwnerUserId="835" LastActivityDate="2014-03-07T01:50:09.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2094" PostTypeId="1" AcceptedAnswerId="2095" CreationDate="2014-03-07T03:22:26.093" Score="25" ViewCount="7290" Body="&lt;p&gt;On Air France 447 the crew had experienced complete failure of the pitot static system, which meant they lost their readings on their airspeed indicators, but according to the &lt;em&gt;Mayday&lt;/em&gt; / &lt;em&gt;Air Crash Investigations&lt;/em&gt; episode the aircraft had detected that the plane was about to enter an aerodynamic stall and the stall warning systems were activated just before the crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How did the A330 in question detect that the plane was on the verge of stalling without the airspeed indicators working?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="22726" LastEditDate="2019-01-10T00:42:34.850" LastActivityDate="2019-01-10T00:42:34.850" Title="How does an A330 detect stall without airspeed?" Tags="&lt;flight-instruments&gt;&lt;stall&gt;&lt;pitot-static&gt;&lt;airbus-a330&gt;&lt;af447-accident&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2095" PostTypeId="2" ParentId="2094" CreationDate="2014-03-07T03:52:34.543" Score="32" Body="&lt;p&gt;Stalls occur based on a wing's angle of attack rather than the aircraft's airspeed.  (In fact, one of the basic facts that all pilots learn in their initial training is that an airplane can stall at &lt;em&gt;any&lt;/em&gt; airspeed).  The A330 measures angle of attack using vanes mounted on the fuselage:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/x2rCA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, below 60 knots, these vanes &lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/recos05juillet2012.en.pdf&quot; rel=&quot;noreferrer&quot;&gt;become ineffective&lt;/a&gt;.  During the AF447 accident, the stall warning only engaged intermittently because the computers detected that the airspeed readings from the blocked pitot tubes were invalid, and therefore silenced the stall warning system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, because of the lack of valid airspeed data, AF447 was no longer in &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_modes_%28electronic%29#Flight_control_laws_.28Airbus.29&quot; rel=&quot;noreferrer&quot;&gt;normal law&lt;/a&gt; (and therefore had no automated angle-of-attack protection), a fact which the pilots may not have been aware of.  By the time the deicing equipment had cleared the pitot tubes, the aircraft was at such an extreme pitch that airspeed indications were still considered invalid, and the stall warning system did not activate.  The computers only activated the stall warning system when the crew pitched down, which brought valid airspeed data back into the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;a href=&quot;http://snpl.com/download.php?id=1901&quot; rel=&quot;noreferrer&quot;&gt;Airbus press release&lt;/a&gt; suggests that this may have contributed to the accident:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We also note that the aircraft, or more specifically the design of the stalling warning system, misled the pilots: &lt;strong&gt;each time they reacted appropriately, the alarm triggered&lt;/strong&gt; inside the cockpit, as though they were reacting wrongly. Conversely, each time the pilots pitched up the plane, the alarm shut off, preventing a proper diagnosis of the situation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis mine)&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-03-07T04:18:37.737" LastActivityDate="2014-03-07T04:18:37.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2096" PostTypeId="2" ParentId="1830" CreationDate="2014-03-07T04:23:47.340" Score="4" Body="&lt;p&gt;As DeltaLima noted, pretty much &lt;strong&gt;&lt;em&gt;all&lt;/em&gt;&lt;/strong&gt; flight modes of a quadcopter are &quot;non-traditional&quot; -- they're a relatively new aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most quadcopter designs lack anything resembling &quot;wings&quot;, so they can't &quot;fly&quot; in an &quot;X-Wing&quot; orientation (with the rotors producing entirely lateral thrust) -- at least not as we traditionally define flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can, as you surmised, do a climb-and-run maneuver in that orientation: Gain a lot of altitude by using vertical thrust, tilt the platform near-90-degrees in the direction you want to travel (so your thrust is pretty much lateral), and accelerate in that direction while rapidly losing altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've no idea if this is more or less efficient than the usual slight tilt they fly with, but it's certainly less stable since you're in vertical free-fall and would need to redirect thrust to be vertical again with enough time/altitude to arrest the descent before an ungraceful impact with the ground.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;X-Wings work so well because the microgravity environment of deep space isn't trying to drag you back to an impact with the ground - it wouldn't work well deep in a planet's gravity well, which is where most of our aircraft operate.&lt;br&gt;&#xA;  Of course if you had access to &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Space_Station&quot; rel=&quot;nofollow&quot;&gt;a microgravity environment with an atmosphere&lt;/a&gt; you could configure a quadcopter to fly like an X-Wing fighter…&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The quadcopter's thrust configuration does open up the option for some interesting maneuvers though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's theoretically possible to &quot;flip&quot; a quadcopter (around at least 8 axes) if you have sufficient altitude (especially if the rotors can be reversed in flight to assist in the maneuvers).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also possible to &quot;rock the wings&quot; (really rocking the whole platform) in many directions by alternating thrust on pairs of rotors.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-07T04:23:47.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2099" PostTypeId="2" ParentId="2078" CreationDate="2014-03-07T05:45:33.870" Score="37" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II#Colors_and_markings&quot;&gt;Wikipedia&lt;/a&gt; cites the biological concept of &lt;a href=&quot;https://en.wikipedia.org/wiki/Mimicry#Automimicry&quot;&gt;automimicry&lt;/a&gt;, or intraspecific mimicry, where a species develops a part of the body which appears similar to another part, e.g. a tail appearing like a head, so that predators become confused as to the orientation or direction of movement of their prey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per egid's answer, this technological form of automimicry ideally helps to degrade an enemy's capability to successfully attack an A-10C (or similarly painted aircraft or vehicle).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also the similar concept of &lt;a href=&quot;https://en.wikipedia.org/wiki/Dazzle_camouflage&quot;&gt;&lt;em&gt;dazzle camouflage&lt;/em&gt;&lt;/a&gt; or &lt;em&gt;razzle dazzle&lt;/em&gt; used on combat and merchant naval ships during World War I.&lt;/p&gt;&#xA;" OwnerUserId="1253" LastEditorUserId="64" LastEditDate="2014-03-09T01:16:33.670" LastActivityDate="2014-03-09T01:16:33.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2100" PostTypeId="2" ParentId="2019" CreationDate="2014-03-07T05:47:19.920" Score="4" Body="&lt;p&gt;&lt;strong&gt;Absolutely not&lt;/strong&gt;, if by “sit in the cockpit” you mean after the door is closed, during the flight, at least on scheduled airline flights in the United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines verify the identity and employment status of would-be jumpseat passengers not only through documents presented by the passenger, which might—as mentioned in another answer—be forged, stolen, or or out of date, but also through databases like the &lt;a href=&quot;http://www.arinc.com/sectors/aviation/aircraft_operations/commercial_aviation/inflight_apps/crew/cass.html&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Cockpit Access Security System&lt;/strong&gt;&lt;/a&gt; (CASS), operated by Rockwell Collins. CASS includes the names &lt;strong&gt;and photographs&lt;/strong&gt; of crew members from each participating airline, and entries are deleted immediately if a crew member’s employment ends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I appreciate others’ concern about disclosure of sensitive security information, but please note that everything in this answer is from public-domain sources, and I am not a “covered person” under the relevant regulations, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=49:9.1.3.4.8&quot; rel=&quot;nofollow&quot;&gt;49 CFR 1520&lt;/a&gt;.)&lt;/p&gt;&#xA;" OwnerUserId="1254" LastActivityDate="2014-03-07T05:47:19.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2101" PostTypeId="2" ParentId="2077" CreationDate="2014-03-07T06:47:53.067" Score="1" Body="&lt;p&gt;You're asking a couple of different questions here, I think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Neither FSIMS nor the FARs specify&lt;/strong&gt; whether a &lt;em&gt;particular&lt;/em&gt; checkride flight must be conducted under part 91 or 135/121.  Regarding medical certificates, &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.5,Ch3,Sec4&quot; rel=&quot;nofollow&quot;&gt;FSIMS 5-887&lt;/a&gt; indicates that for ATP 121/135 applicants:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CREW QUALIFICATIONS. The crew, &lt;em&gt;with the exception of the applicant&lt;/em&gt;, must be qualified and current. [emphasis added]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As for checkrides, they're part 61.&lt;/strong&gt;.  So as to the part of your question that asks about what medical you need &lt;em&gt;during a checkride&lt;/em&gt;, &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.23&quot; rel=&quot;nofollow&quot;&gt;FAR 61.23(a)(3)&lt;/a&gt; says that you need at least a 3rd class medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, FSIMS guidance for examiners conducting 121/135 checks occasionally makes reference to &quot;limitations as specified by the certificate holder's operating manual&quot;.  Since this wouldn't make sense if the flight was conducted under part 91, I suspect that:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;There is no defined answer to your question&lt;/li&gt;&#xA;&lt;li&gt;The flight that a checkride happens during is conducted according to whichever rules would otherwise apply&lt;/li&gt;&#xA;&lt;li&gt;Checkride flights are just special that way&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-03-07T14:16:44.343" LastActivityDate="2014-03-07T14:16:44.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2102" PostTypeId="2" ParentId="2078" CreationDate="2014-03-07T12:00:10.503" Score="59" Body="&lt;p&gt;Also used by the South African Air Force on its Gripen fighter aircraft and, before that, its Cheetah (upgraded Mirage) fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The intention is to create momentary uncertainty as to which direction an aircraft may turn, both for air-to-air encounters against other aircraft and when doing low-level manoeuvring in the ground-attack role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An image of a South African Air Force Gripen C, showing the false cockpit on the bottom:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/prlhq.jpg&quot; alt=&quot;SAAF Gripen C&quot;&gt;&#xA;&lt;br/&gt;&lt;em&gt;By Brent Best&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And an image of a South African Air Force Cheetah C showing the same:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XBnCg.jpg&quot; alt=&quot;SAAF Cheetah C&quot;&gt;&#xA;&lt;br/&gt;&lt;em&gt;By Christo Crous&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the diamond-shape on the bottom of the Cheetah C. A similar pattern is painted on the top surface of the SA Air Force's Gripens. This reportedly helps create more uncertainty when seen in  brief glimpses during combat, similar to the way dazzle camouflage on ships in WWI worked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an illustration, taken from a flight sim, of what the effect looks like on a Cheetah C with a mostly 'clean' configuration (no drop tanks or bombs):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lEQeU.jpg&quot; alt=&quot;SAAF Cheetah C (simulated)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;South African Air Force fighter aircraft have used the false cockpit and diamond-shape camouflage ideas since the last 1980s, after proving the concepts through testing.&lt;/p&gt;&#xA;" OwnerUserId="1263" LastEditorUserId="167" LastEditDate="2014-03-07T14:39:31.803" LastActivityDate="2014-03-07T14:39:31.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2103" PostTypeId="2" ParentId="2090" CreationDate="2014-03-07T13:41:08.973" Score="10" Body="&lt;p&gt;Although the FAA still allows lap children, the NTSB does not recommend it. According to the &lt;a href=&quot;http://www.ntsb.gov/safety/children.html&quot;&gt;NTSB Child and Youth Transportation Safety webpage&lt;/a&gt; (emphasis my own):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NTSB Child and Youth Transportation Safety Initiative will promote&#xA;  child occupant safety in all modes of transportation with a focus on&#xA;  educating parents and caregivers about ways to keep children safe when&#xA;  traveling. The NTSB will also continue to push for adoption of its&#xA;  recommendations concerning child occupant safety, such as:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Requiring separate seats and restraints for all airplane occupants, and requiring children younger than 2 to be restrained by&#xA;  an appropriate child restraint system during air travel&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also issued a &lt;a href=&quot;http://www.ntsb.gov/doclib/safetyalerts/SA_015.pdf&quot;&gt;safety alert on the subject&lt;/a&gt;, in which they advise parents to &quot;Purchase a ticket for all children younger than 2 years and restrain them in a child restraint system certified for use on aircraft&quot;, &quot;Ensure that infants and small children are restrained in a child restraint appropriate to their size.&quot;, and to &quot;Ensure that all children are properly restrained during takeoff, landing, and turbulent conditions or when the seat belt sign is illuminated&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip side, seat prices are expensive, and many parents may simply choose not to fly if they are forced to buy a separate seat for their infant, so airlines and the FAA do have some pressure to continue to permit the practice. &lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-07T13:41:08.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2104" PostTypeId="2" ParentId="2094" CreationDate="2014-03-07T13:50:59.553" Score="5" Body="&lt;p&gt;&lt;em&gt;Aircraft can stall at any airspeed&lt;/em&gt;, the only real indicator for a stall is an angle of attack indicator. This is because weight, icing, flaps, G-forces being pulled, and speed all effect the aircraft's stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most large aircraft, including the A330, have angle of attack indicators that detect the high angle of attack which precedes a stall. Although the other instruments had failed, the angle of attack meter was still functioning, though not very well.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-07T13:50:59.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2105" PostTypeId="2" ParentId="2061" CreationDate="2014-03-07T14:01:03.847" Score="3" Body="&lt;p&gt;According to the FAA in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99583&quot; rel=&quot;nofollow&quot;&gt;AC33.70-1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) The applicant should validate and maintain the accuracy of the&#xA;  engine flight cycle over the life of the design. The extent of the&#xA;  validation depends on the approach taken in the development of the&#xA;  engine flight cycle. For example, a conservative flight cycle where&#xA;  all the variables are placed at the most life damaging value would&#xA;  require minimum validation. A flight cycle that attempts to accurately&#xA;  represent the actual flight profile, but is inherently less&#xA;  conservative, would require more extensive validation. Applicants may&#xA;  apply further refinements to the engine flight cycle when significant&#xA;  field operational data is obtained.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-07T14:01:03.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2106" PostTypeId="2" ParentId="1755" CreationDate="2014-03-07T14:08:04.387" Score="-3" Body="&lt;p&gt;The 737 MAX is more fuel efficient than the A320ceo. The A320neo, however, has marginally better range and fuel efficiency than the 737 MAX, but it is not in production yet.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-07T14:08:04.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2107" PostTypeId="1" AcceptedAnswerId="2109" CreationDate="2014-03-07T14:12:40.987" Score="5" ViewCount="5850" Body="&lt;p&gt;What is the function of the scissors link on the rotor of a helicopter?&lt;br&gt;&#xA;I assume it has something to do with the flight controls, but I'm not quite sure what.&lt;/p&gt;&#xA;" OwnerUserId="1057" LastEditorUserId="247" LastEditDate="2014-03-12T09:42:05.993" LastActivityDate="2017-05-02T15:31:04.500" Title="What is the function of the scissors link in helicopter flight controls?" Tags="&lt;flight-controls&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2108" PostTypeId="2" ParentId="2083" CreationDate="2014-03-07T14:36:20.693" Score="3" Body="&lt;p&gt;I can't be sure without seeing actual documentation of the thing, but I would expect:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight path is direction of the total velocity vector, i.e. the direction the plane is flying, in Earth-relative frame of reference. This differs from direction of longitudinal axis by alpha (angle-of-attack), beta (side-slip) and wind.&lt;/li&gt;&#xA;&lt;li&gt;Track is projection of flight path to horizontal plane.&lt;/li&gt;&#xA;&lt;li&gt;Heading is projection of the longitudinal axis to horizontal plane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Then:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;flight path acceleration would be simply acceleration along the flight path&lt;/li&gt;&#xA;&lt;li&gt;along track and across track are, well, along and across track as defined above.&lt;/li&gt;&#xA;&lt;li&gt;vertical is vertical; should not include gravity, so when maintaining vertical speed it should be 0.&lt;/li&gt;&#xA;&lt;li&gt;unbiased normal acceleration is most probably what is also called inertial normal acceleration, that is acceleration without gravity.&lt;/li&gt;&#xA;&lt;li&gt;along and across heading are, well, along and across heading as defined above.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-03-07T14:36:20.693" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2109" PostTypeId="2" ParentId="2107" CreationDate="2014-03-07T14:55:04.577" Score="6" Body="&lt;p&gt;the scissor link ensures the upper swashplate rotates with the rotor blades (and the lower with the body) while ensuring enough movement for the plate to control the craft (tilting and up and down).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qDoi3.jpg&quot; alt=&quot;the connector between the mast and the upper swash plate, has a counter weight&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://en.wikipedia.org/wiki/File:Robinson-Rotorhead.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://en.wikipedia.org/wiki/File:Robinson-Rotorhead.jpg&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To keep the stationary swashplate from rotating with the rotor, a scissor mechanism is added. The scissor connects the swashplate to the fuselage. The scissor consists of 2 parts which are connected by a hinge. One end is connected to the helicopter using a hinge, while the other is connected using a ball joint. This means that the swashplate can move freely up and down, and can freely tilt in any direction, but can't rotate around the mast.&lt;a href=&quot;http://cesarvandevelde-constructieleer.blogspot.nl/2011/01/swashplate-mechanism-of-r44.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;[source]&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;this is needed because the control linkage is typically attached with balljoints which would otherwise allow for too much relative movement.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-03-07T15:29:19.680" LastActivityDate="2014-03-07T15:29:19.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2110" PostTypeId="2" ParentId="2090" CreationDate="2014-03-07T15:45:47.340" Score="10" Body="&lt;p&gt;Cranfield University in the UK has long been involved in research on child restraint systems in aircraft.&#xA;&lt;a href=&quot;http://www.eurekalert.org/pub_releases/2000-01/CU-Cpfg-3001100.php&quot;&gt;http://www.eurekalert.org/pub_releases/2000-01/CU-Cpfg-3001100.php&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Roger Hardy, Director of the Cranfield Impact Centre believes, &quot;It is&#xA;  time to get children off laps. End of story.&quot; A topic discussed at a&#xA;  recent seminar in Washington USA, which focused on 'Child Restraint&#xA;  Use in Aircraft' gave experts the chance to put across their views on&#xA;  this crucial issue.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and list a number of relevant publications&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cranfieldimpactcentre.com/publications-archive&quot;&gt;http://www.cranfieldimpactcentre.com/publications-archive&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hardy, R.N., “The Restraint of Children in Aircraft”, Proceedings of National Transportation Safety Board Child Restraint in Aircraft meeting, Washington D.C. December 1999.&lt;/li&gt;&#xA;&lt;li&gt;Hardy, R.N., “Dual Child Occupancy of an Aircraft Seat”, CAA Paper 93013, July 1993.&lt;/li&gt;&#xA;&lt;li&gt;Hardy, R.N., “The Restraint of Infants and Young Children in Aircraft”, CAA Paper 92020, December 1992.&lt;/li&gt;&#xA;&lt;li&gt;Hardy, R.N., “Restraint of Infants and Young Children”, 8th Annual International Aircraft Cabin Safety Symposium, Costa Mesa, California, February 1991.&lt;/li&gt;&#xA;&lt;li&gt;Hardy, R.N., “Infant and Child Safety Research”, European Cabin Safety Conference, Gatwick Airport, London, September 1990.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="769" LastEditorUserId="769" LastEditDate="2014-03-07T15:55:22.483" LastActivityDate="2014-03-07T15:55:22.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2111" PostTypeId="1" AcceptedAnswerId="2114" CreationDate="2014-03-07T19:43:08.690" Score="37" ViewCount="34742" Body="&lt;p&gt;It seems like a lot of the newer airliners have winglets or wing fences. How do they improve aircraft performance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YZl4r.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="11671" LastEditDate="2020-11-17T01:21:05.327" LastActivityDate="2020-11-17T01:22:57.373" Title="What do winglets do to increase aircraft performance?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;winglets&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2112" PostTypeId="2" ParentId="2111" CreationDate="2014-03-07T20:03:58.273" Score="12" Body="&lt;p&gt;Winglets, raked wingtips, fences, sharklets all do the same thing; reduce drag.  When the wing is working hard (high AoA), it will produce a lot of this kind of drag since vortices of all kinds will be stronger.  Winglets makes the passage of air from the bottom of the wing to the lower pressure top of the wing more difficult, thus reducing induced drag.&lt;/p&gt;&#xA;&lt;p&gt;The big manufacturers explored offering winglet retrofit kits to their customers but at the time, it wasn't economical since fuel was so cheap.  These days, however, the retrofits pay for themselves fairly quickly even on airplanes wings that have a fairly high aspect ratio.  Every 737/757/767 guy that I talk to says they get in the neighborhood of a 4-6% boost in fuel savings.&lt;/p&gt;&#xA;&lt;p&gt;On an tangentially related topic, the hump from the satellite internet antennas has a negligible impact on performance, less than 1% according to the few guys that I talked to.&lt;/p&gt;&#xA;" OwnerUserId="835" LastEditorUserId="11671" LastEditDate="2020-11-17T01:22:57.373" LastActivityDate="2020-11-17T01:22:57.373" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2113" PostTypeId="2" ParentId="2111" CreationDate="2014-03-07T20:05:15.827" Score="19" Body="&lt;p&gt;Wing generates lift by creating area of higher pressure below and area of lower pressure above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the wing tip, some air flows around the tip, reducing the pressure differential and thus the efficiency of the wing. This is called transverse flow. The wing tip reduces this flow, thus improving the efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect of wing tip is actually similar to making the wing a bit longer, but since the wing tip does not produce lift itself, it is less stressed and therefore can be lighter, even though the extension would be about 1/3 shorter for comparable efficiency.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-03-07T20:05:15.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2114" PostTypeId="2" ParentId="2111" CreationDate="2014-03-07T20:05:52.503" Score="31" Body="&lt;p&gt;they reduce the &lt;a href=&quot;http://en.wikipedia.org/wiki/Wingtip_vortices&quot; rel=&quot;noreferrer&quot;&gt;wingtip vortex&lt;/a&gt; and the associated drag by deflecting the air that wants to escape over the tip back down&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eZyKZ.png&quot; alt=&quot;http://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/737-NG_winglet_effect_%28simplified%29.svg/800px-737-NG_winglet_effect_%28simplified%29.svg.png&quot;&gt;(&lt;a href=&quot;http://en.wikipedia.org/wiki/File:737-NG_winglet_effect_%28simplified%29.svg&quot; rel=&quot;noreferrer&quot;&gt;source: wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-03-07T20:05:52.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2115" PostTypeId="1" AcceptedAnswerId="2118" CreationDate="2014-03-07T21:54:51.240" Score="15" ViewCount="4097" Body="&lt;p&gt;An aviation expert claimed to me that a propeller is a wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I understand that propellers use similar principles to generate force, it muddied the definition of a rotary wing aircraft vs a fixed wing aircraft.  If the propeller of a fixed wing aircraft is considered a wing, what is the distinction between the two?  Is it how much surface area each type of wing works on?  Is it the direction of force?&lt;/p&gt;&#xA;" OwnerUserId="1073" LastEditorUserId="6" LastEditDate="2018-11-11T21:19:43.113" LastActivityDate="2019-07-17T09:07:20.193" Title="Is a propeller a wing?" Tags="&lt;propeller&gt;&lt;fixed-wing&gt;&lt;rotary-wing&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2118" PostTypeId="2" ParentId="2115" CreationDate="2014-03-07T23:05:09.690" Score="18" Body="&lt;p&gt;I think most people would say the answer is &lt;strong&gt;&lt;em&gt;no&lt;/em&gt;&lt;/strong&gt;. Consider the &lt;a href=&quot;http://dictionary.reference.com/browse/wing?s=t&quot;&gt;dictionary.com definition&lt;/a&gt; as it relates to Aeronautics:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;9. Aeronautics .&lt;/em&gt;&#xA;  a. one of a pair of airfoils attached transversely to the fuselage of an aircraft and providing lift.&#xA;  b. both airfoils, taken collectively.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The wings are the big airfoils which are responsible for generating most of the vertical lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A colloquial test of this definition would be to grab a CFI and ask him/her to &quot;point out the wings on this airplane to me.&quot; They won't point out the propeller. (&lt;em&gt;Not a scientific experiment&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, both wings and propellers are airfoils (and so are the other wing-like surfaces such as the vertical and horizontal stabilizers). You might get some disagreement about whether those other surfaces are wings, but I believe the answer is still no. There is nothing to be gained by calling them wings, and only leads to ambiguity. We already have a word which describes lifting surfaces in-general, and again, it's &lt;em&gt;airfoil&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2014-03-07T23:11:40.853" LastActivityDate="2014-03-07T23:11:40.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2119" PostTypeId="2" ParentId="2115" CreationDate="2014-03-08T00:15:06.513" Score="-3" Body="&lt;p&gt;After doing a little more research, I have come to the conclusion that the answer is probably no. Since wings produce lift, I would argue that a propeller is not a wing since it does not produce lift, but thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since thrust is pretty much always perpendicular to lift, I can't see how the propeller would ever actually produce lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YXsd2.png&quot; alt=&quot;lift,thrust&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-08T00:15:06.513" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2120" PostTypeId="2" ParentId="2115" CreationDate="2014-03-08T00:16:37.433" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;An aviation expert reminded me that a propeller is a wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is not false- a wing generates lift by creating a pressure difference, in the same way a propeller does. Wing typically refers to the structure lifting the main weight of the aircraft, while a propeller generates thrust, so from definition it's probably incorrect, from a theoretical standpoint it's the same principle.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While I understand that propellers use similar principles to generate&#xA;  force, it muddied the definition of a rotary wing aircraft vs a fixed&#xA;  wing aircraft. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A fixed wing aircraft will move at speed to generate sufficient lift to get airborne. A helicopter will be able to lift off vertically by spinning the blades quickly enough, which will have the same effect as moving forward.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the propeller of a fixed wing aircraft is considered a wing, what is the distinction between the two? Is it how much surface area each type of wing works on? Is it the direction of force?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Propeller thrust is directed forwards. In level flight it contributes very little to lifting the plane up- that's left to the wings to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotary wing aircraft's blades do really work as a propeller: By increasing the angle of attack on one side, you generate more thrust, and the helicopter flies in the direction you want it to, since there's a force vector in that direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8exsv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8exsv.jpg&quot; alt=&quot;heli&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://media.tiscali.co.uk/images/feeds/hutchinson/ency/c04919.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;tiscali.co.uk&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Distinction&lt;/strong&gt; between the two: &lt;em&gt;Rotorcraft&lt;/em&gt; generate the thrust to lift off themselves. A &lt;em&gt;propeller&lt;/em&gt; generates the thrust (and in turn speed) necessary to create lift over fixed surfaces.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-07-17T09:07:20.193" LastActivityDate="2019-07-17T09:07:20.193" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2121" PostTypeId="2" ParentId="2115" CreationDate="2014-03-08T00:21:44.077" Score="12" Body="&lt;p&gt;Is a propeller a wing? Maybe.  It depends on how pedantic you feel like being about your definitions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A propeller is certainly an airfoil (usually several of them - each blade is an airfoil, and you can have &lt;a href=&quot;http://en.wikipedia.org/wiki/Single-blade_propeller&quot; rel=&quot;nofollow noreferrer&quot;&gt;one blade&lt;/a&gt;, two, three, four, or more attached to a hub).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wing is also an airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerodynamically a wing and a propeller function the same way: Air moves over the surface of the airfoil(s), producing &quot;lift&quot;. In the case of the wing the lift is mainly vertical and we call it &quot;lift&quot;, while in the case of a propeller it's mainly horizontal and we call the resulting force &quot;thrust&quot; instead.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;My two cents, ignoring all the dictionary pedantry? A propeller is an airfoil, but it is &lt;em&gt;not&lt;/em&gt; a wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why?&lt;/em&gt;&lt;/strong&gt; Simple:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm flying along and my propeller magically vanishes I'm now flying a &lt;em&gt;really inefficient&lt;/em&gt; glider.&lt;br&gt;&#xA;My day is ruined and when I catch the guy with the genie-in-a-lamp who wished my propeller away I'll probably beat them up, but I have a fair chance of putting the aircraft on the ground without killing myself or anyone else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm flying along and my right wing magically vanishes the genie-posessing miscreant is safe as I'm almost certainly going to die. All the lift from the remaining wing is going to try to flip the aircraft over, and I'm nowhere near skilled enough to &lt;a href=&quot;https://skeptics.stackexchange.com/questions/9884/&quot;&gt;keep control with a missing wing and land safely&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:46:45.343" LastActivityDate="2014-03-08T00:21:44.077" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2122" PostTypeId="5" CreationDate="2014-03-08T05:32:12.817" Score="0" Body="&lt;p&gt;An &quot;experimental&quot; aircraft is one that does not have &lt;a href=&quot;https://en.wikipedia.org/wiki/Type_certificate&quot; rel=&quot;nofollow noreferrer&quot;&gt;a type certificate&lt;/a&gt; issued by the FAA or another regulator, i.e. it is considered a 'one-off' aircraft, rather than a standard type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Experimental aircraft include homebuilt aircraft and aircraft used for special purposes (e.g. research, air racing), but they do not not usually include military aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Experimental_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Experimental aircraft&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Experimental Category&lt;/a&gt; (FAA)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="62" LastEditDate="2017-12-04T13:24:37.687" LastActivityDate="2017-12-04T13:24:37.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2123" PostTypeId="4" CreationDate="2014-03-08T05:32:12.817" Score="0" Body="For questions about experimental aircraft that have not been granted a type certificate by a regulatory agency." OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2016-07-08T14:32:34.033" LastActivityDate="2016-07-08T14:32:34.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2124" PostTypeId="1" CreationDate="2014-03-08T07:21:43.047" Score="17" ViewCount="2176" Body="&lt;p&gt;In 1963, &lt;a href=&quot;http://www.theaviationzone.com/factsheets/c130_forrestal.asp&quot;&gt;the C-130&lt;/a&gt; was tested by the US Navy for air carrier operations. Have there been any other &lt;em&gt;comparable&lt;/em&gt; or larger aircraft that have landed and taken off from the deck of an aircraft carrier?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &lt;em&gt;large&lt;/em&gt;, I am referring to two parameters: wingspan and weight.&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="193" LastEditDate="2014-03-08T13:00:20.603" LastActivityDate="2017-12-07T13:05:15.447" Title="Which are the largest planes to have operated on an aircraft carrier?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;aircraft-carrier&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2125" PostTypeId="2" ParentId="2124" CreationDate="2014-03-08T10:10:14.940" Score="5" Body="&lt;p&gt;The KC-130F that performed the trials from the USS Forrestal in 1963 appears to be the largest, I know of nothing else of that size, weight and span that has done it.&lt;/p&gt;&#xA;" OwnerUserId="1263" LastActivityDate="2014-03-08T10:10:14.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2126" PostTypeId="1" AcceptedAnswerId="2127" CreationDate="2014-03-08T12:11:28.127" Score="27" ViewCount="5810" Body="&lt;p&gt;When an engine fire is detected the fire handle lights up and the pilot pulls it to extinguish the fire. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why doesn't it do that automatically? &#xA;Why does the pilot have to pull the handle?&lt;/p&gt;&#xA;" OwnerUserId="1308" LastEditorUserId="64" LastEditDate="2015-01-08T19:48:03.870" LastActivityDate="2015-07-17T15:02:19.630" Title="Why don't aeroplanes automatically put out engine fires?" Tags="&lt;emergency&gt;&lt;fire&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2127" PostTypeId="2" ParentId="2126" CreationDate="2014-03-08T12:38:56.903" Score="35" Body="&lt;p&gt;Shutting off the computer is difficult from a technical implementation standpoint. You're handing over a lot of power to the computers and sensors letting it shut down an engine, where these usually do not have access and control. This is certainly not always a good idea.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pulling the fire handle is a pretty aggressive move: It will typically disable hydraulics, electrical power, and bleed air coming from that engine. If you're not prepared for it, it can end badly.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The engine will often be partially functional, depending on the type of failure. If you get dual engine fire indications, you'd probably wait with shutting them down, if doing that at all. This sort of behaviour would have to be coded into the flight computers.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I don't think there are any catastrophic consequences of not switching the engine within 8 seconds rather than maybe 2 seconds. It does not make a great difference. To set off the detectors, it must already have spread a little. I don't think you could do it much faster with the pilot staying updated on what's going on.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Needless to say, computers sometimes get things wrong. There is a human level to check what's going on before proceeding.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are times when you don't want the computer doing it's own thing. &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-SUPP_TECH-SEQ07.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airbus states that&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If an engine fire occurs during takeoff or go-around, the Pilot Flying shall first establish and stabilise the aircraft on a safe climb path and then proceed with the ENG FIRE procedure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;em&gt;Footnote:&#xA;It could certainly be done, but with the pilot-computer relationship on current flightdecks it's not a good idea.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-09T16:49:32.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2128" PostTypeId="2" ParentId="2124" CreationDate="2014-03-08T12:56:04.260" Score="8" Body="&lt;p&gt;U-2s also &lt;a href=&quot;https://www.youtube.com/watch?v=I_3WeYXDKQ0&quot;&gt;landed&lt;/a&gt; and &lt;a href=&quot;http://youtu.be/L8HMPMYL19E?t=2m30s&quot;&gt;took off&lt;/a&gt; from aircraft carriers.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-03-08T19:40:14.987" LastActivityDate="2014-03-08T19:40:14.987" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2129" PostTypeId="2" ParentId="2126" CreationDate="2014-03-08T13:07:26.303" Score="8" Body="&lt;p&gt;You think about the danger of a fire. The engine is still fed with fuel and the fire maybe damages other parts of the aircraft or leads to an explosion. For sure these danger is real, but on the other hand we are talking about losing an engine, half the thrust of modern airliners. There are two reasons, I can think of, why this is not done automatically.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Even though the engine is on fire it is still producing thrust. Not as much as a good engine, with an extremely high probability to fail completely and for sure a bunch of other risks, but still thrust you maybe need to clear obstacles, or to escape any other danger. Think about an engine fire occurring during take off (past $V_1$), on initial go-around, or while escaping a downburst, situations you really don't need a loss of thrust. Also on takeoff roll prior reaching $V_{MCG}$ (minimum control speed on ground) you first like to have your directional control and the possibility to safely decelerate the aircraft prior to securing the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For sure you are aware that it is a hard decision to shut down an engine and also my first point will remember you of some of the dangers doing it, but in some situations (e.g. fire) it have to be done to prevent further damage. This decision should not be done by computer because this would just be an extra chance that something goes wrong. This system would need a lot of logics, not only 'over temperature -&gt; disconnect the engine, shoot a bottle'. Why should this be done by a computer, which possibly extinguishes a good engine during climb out, only because of a faulty indication, or a computer error if there are two well trained pilots capable to deal with the situation?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You already mentioned the 'flow' how to extinguish an engine fire on most modern airliners. Identify the problem, close the throttle (cut off the fuel) pull the fire handle, see what happens, eventually shoot a fire bottle, or even the second. That's really no hard work but a bunch of factors which needs to be taken into account. In my eyes this is still a job which should be in the hand of the flight crew. &lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="97" LastEditDate="2014-04-16T23:58:14.440" LastActivityDate="2014-04-16T23:58:14.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2130" PostTypeId="2" ParentId="2126" CreationDate="2014-03-08T14:51:05.037" Score="18" Body="&lt;p&gt;There are a few reasons why this might not be a good idea:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An engine fire in a typical jet aircraft does not necessarily need to be shut down &lt;strong&gt;immediately&lt;/strong&gt;.  Most of the jets that I have flown include a concept along the lines of &quot;Shut down the engine &lt;strong&gt;&lt;em&gt;if you are not in a thrust critical situation&lt;/em&gt;&lt;/strong&gt;.&quot;  There is a saying that you never want to accomplish anything &lt;strong&gt;fast&lt;/strong&gt; in a jet airplane (other than put on your oxygen mask if the cabin depressurizes).  It is possible that shutting an engine down could put you in a worse situation than letting it burn a little longer while you climb above an obstacle.&lt;/li&gt;&#xA;&lt;li&gt;There are times when there is a false indication of a fire.  This could be caused by a faulty sensor or a hot bleed air leak on the engine.  In this case, you don't always need to shut the engine down.  Some aircraft include reducing the power to idle first to see if the fire indication goes away.&lt;/li&gt;&#xA;&lt;li&gt;We don't want a faulty computer to shut down a perfectly good engine.  Many fire handles are mechanically connected to the fuel shutoff valves making it so that it is nearly impossible to &quot;accidentally&quot; activate this feature.  This design also allows you to shut down the engine even if there is no electrical power whatsoever.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-08T14:51:05.037" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2131" PostTypeId="1" AcceptedAnswerId="2132" CreationDate="2014-03-08T14:56:31.887" Score="12" ViewCount="2468" Body="&lt;p&gt;The FAA issues Letters of Interpretation and Chief Counsel Opinions in order to clarify existing rules and regulations.  Where these can be found and searched when looking for clarification of a rule?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2019-05-28T01:53:47.513" Title="Where can FAA Letters of Interpretation be found?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2132" PostTypeId="2" ParentId="2131" CreationDate="2014-03-08T14:56:31.887" Score="11" Body="&lt;p&gt;The FAA Regulations Division maintains a &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/&quot; rel=&quot;nofollow noreferrer&quot;&gt;webpage&lt;/a&gt; which includes a searchable database of &quot;Legal Interpretations &amp;amp; Chief Counsel's Opinions&quot;.  It includes the following disclaimer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Legal Interpretations and the Chief Counsel's opinions are now&#xA;  available at this site.  Please note that not all interpretations or&#xA;  Chief Counsel's opinions are available at this time.  This database&#xA;  consists of legal interpretations issued from 1990 to the present and&#xA;  will be updated on a regular basis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The letters can be searched by year and/or keyword.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2019-05-28T01:53:47.513" LastActivityDate="2019-05-28T01:53:47.513" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2133" PostTypeId="1" CreationDate="2014-03-08T15:16:19.590" Score="7" ViewCount="4195" Body="&lt;h1&gt;FAA Rule:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The duration of FAA medical certificates is specified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2766b8a7c241f67946e3d8e92ffd7d9a&amp;amp;node=14:2.0.1.1.2.1.1.17&amp;amp;rgn=div8&quot;&gt;14 CFR 61.23&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example would be for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A first-class medical certificate&lt;/li&gt;&#xA;&lt;li&gt;Applicant is under age 40&lt;/li&gt;&#xA;&lt;li&gt;Applicant is an airline transport pilot certificate for pilot-in-command privileges&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this case:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Then your medical certificate expires, for that operation, at the end of the last day of the 12th month after the month of the date of examination shown on the medical certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So this clearly states that if I pass my medical on January 1st 2014 then my medical is good until the end of the day on January 31st 2015.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;ICAO Rule:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;However, I have been told that ICAO rules state that the medical expires 12 months &lt;strong&gt;&lt;em&gt;to the day&lt;/em&gt;&lt;/strong&gt; from when it was issued, which would mean that it would no longer be valid as of January 1st, 2015.  (A reference for this would be great.)&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Question:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;As the holder of an FAA pilot license, with the above FAA issued medical, may I legally fly outside of the US after January 1st 2015 (but before February 1st 2015)?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-06-22T08:02:11.530" LastActivityDate="2016-06-22T08:02:11.530" Title="What is the validity duration of FAA Medical for international flights?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2134" PostTypeId="2" ParentId="2133" CreationDate="2014-03-09T03:23:58.930" Score="4" Body="&lt;p&gt;I believe the ICAO regulation you are thinking of is this one:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Excerpts from ICAO Annex 1- Personnel Licensing&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“1.2.5.2 Except as provided in 1.2.5.2.1, 1.2.5.2.2, 1.2.5.2.3,&#xA;  1.2.5.2.4 and 1.2.5.2.5, a Medical Assessment issued in accordance with 1.2.4.5 and 1.2.4.6 shall be valid from the date of the medical&#xA;  examination for a period not greater than:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;60 months for the private pilot licence — aeroplane;  12 months for&#xA;  the commercial pilot licence — aeroplane;  12 months for the airline&#xA;  transport pilot licence — aeroplane;”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It also indicates the following in a note:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“Note 2 — When calculated in accordance with 1.2.5.2 and its&#xA;  sub-paragraphs, the period of validity will, for the last month&#xA;  counted, include the day that has the same calendar number as the date&#xA;  of the medical examination or, if that month has no day with that&#xA;  number, the last day of that month.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In ICAO Annex 1, 2.4.1.6, the medical requirement for a commercial&#xA;  pilot is prescribed. It states:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“2.4.1.6 Medical fitness&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The applicant shall hold a current Class 1 Medical Assessment.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In ICAO Annex 1, 2.5.1.6, the medical requirement for an airline&#xA;  transport pilot is prescribed. It states:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“2.5.1.6 Medical fitness&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The applicant shall hold a current Class 1 Medical Assessment.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“6.1.1 Classes of Medical Assessment&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Three classes of Medical Assessment shall be established as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) Class 1 Medical Assessment; applies to applicants for, and holders&#xA;  of:  — commercial pilot licences — aeroplane and helicopter  — airline&#xA;  transport pilot licences — aeroplane and helicopter  — flight&#xA;  navigator licences  — flight engineer licences&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) Class 2 Medical Assessment; applies to applicants for, and holders&#xA;  of:  — private pilot licences — aeroplane and helicopter  — glider&#xA;  pilot licences  — free balloon pilot licences&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c) Class 3 Medical Assessment; applies to applicants for, and holders&#xA;  of:  — air traffic controller licences.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, ICAO is not involved in &lt;em&gt;enforcement&lt;/em&gt; but rather coming up with standards, which would then be enforced (if adopted) by the member country's aviation authority.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are many differences to be aware of when flying outside the&#xA;  United States (U.S.). International Civil Aviation Organization (ICAO)&#xA;  rules prevail. Member states follow ICAO guidelines as published, with&#xA;  differences noted, in their official Aeronautical Information&#xA;  Publication (AIP).&#xA;  &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ifim/intl_overview/&quot;&gt;http://www.faa.gov/air_traffic/publications/ifim/intl_overview/&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For example, the EASA (European Aviation Safety Agency) has rules very similar to the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MED.A.055  Validity, revalidation and renewal of medical certificates &#xA;  (a)  Validity  (1) &#xA;  Class 1 medical certificates shall be valid for a period of 12 months. &#xA;  (2) &#xA;  Notwithstanding to paragraph (1) the period of validity shall be reduced to 6 months for pilots &#xA;  who:  (i) &#xA;  are engaged in single­pilot commercial air transport operations carrying passengers and &#xA;  have reached the age of 40  (ii)  have reached the age of 60&#xA;  (&lt;a href=&quot;http://easa.europa.eu/rulemaking/docs/npa/2008/2008-17/NPA%202008-17c.pdf&quot;&gt;http://easa.europa.eu/rulemaking/docs/npa/2008/2008-17/NPA%202008-17c.pdf&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, according to this report: &lt;a href=&quot;http://dspace.mit.edu/bitstream/handle/1721.1/35725/FlightOpsICATfinal2.pdf&quot;&gt;http://dspace.mit.edu/bitstream/handle/1721.1/35725/FlightOpsICATfinal2.pdf&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air carrier operations are generally regulated by the country of&#xA;  registration and the sovereignty in which the operation is conducted,&#xA;  including the Federal Aviation Administration (FAA) in the USA and the&#xA;  Joint Aviation Authority (JAA) in Europe. International flights may&#xA;  also fall under the jurisdiction of ICAO (International Civil Aviation&#xA;  Organization) when operating abroad (U.S.-based carriers are governed&#xA;  by both FAA  and ICAO regulations when conducting international&#xA;  operations.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you might be legal until you hit the international waters.  At the very most you might be able to go abroad, but then not be legal to fly back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The National Business Aviation Association (NBAA) recommends that pilots comply with the strictest interpretation of the law (so in this case, have the appropriate compliance with ICAO standards) to avoid having to explain the nuances between the two sets of regulations. &#xA;(&lt;a href=&quot;http://www.nbaa.org/admin/personnel/medical/medical-certificates.php&quot;&gt;http://www.nbaa.org/admin/personnel/medical/medical-certificates.php&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2014-03-09T03:23:58.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2135" PostTypeId="1" CreationDate="2014-03-09T11:44:28.773" Score="10" ViewCount="14119" Body="&lt;p&gt;I am just curious about this... during one flight on Airbus A321 we experienced turbulence and the pilot told us that the wind speed is 150 km/h, so we won't get drinks and snacks due to safety reasons. The question is: Was that wind speed 'normal' or 'dangerous'? What could happen?&lt;/p&gt;&#xA;" OwnerUserId="1325" LastEditorUserId="1696" LastEditDate="2015-02-15T21:35:27.483" LastActivityDate="2015-04-08T09:48:00.760" Title="Is a wind speed of 150 km/h dangerous during a flight in an Airbus A321?" Tags="&lt;wind&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2136" PostTypeId="2" ParentId="2135" CreationDate="2014-03-09T13:18:34.137" Score="9" Body="&lt;p&gt;It's not unusual for aircraft to experience a lot of wind at altitude. In fact, there's a &lt;a href=&quot;http://www.groundspeedrecords.com/&quot; rel=&quot;noreferrer&quot;&gt;website&lt;/a&gt; dedicated to speed records- all of those shown would be impossible without the help of the wind boosting the aircraft in addition to its normal speed. Many people have unknowingly travelled at a velocity faster than the speed of sound on the ground when crossing the Atlantic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I'm not too familiar with it, I think that jetstreams and the like have a tendency to develop more air pockets and turbulence than calm air, including &lt;a href=&quot;http://en.wikipedia.org/wiki/Clear-air_turbulence&quot; rel=&quot;noreferrer&quot;&gt;clear air turbulence&lt;/a&gt;, where there are no visual cues before the turbulence hits. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many incidents happen when people are unprepared for a bounce at cruise altitude, probably hence the pilots decision. A broken ankle is not unheard of. As for catastrophic consequences, they are very rare. Typically, the pilot will slow the aircraft down a little to reduce shaking and stress on the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an incident on a Cathay Pacific 747 around a month ago, midflight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DGA6N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passengers reported the turbulence appeared to have lasted for about 2&#xA;  minutes, at the time the fasten seat belt signs were not illuminated,&#xA;  passengers and cabin crew were moving through the cabin, when the&#xA;  aircraft suddenly and unexpectedly jolted throwing passengers and&#xA;  cabin crew to the ceiling causing damage to ceiling panels and&#xA;  overhead lockers. &lt;a href=&quot;http://avherald.com/h?article=4703406d&quot; rel=&quot;noreferrer&quot;&gt;Aviation Herald&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="167" LastEditDate="2014-03-09T17:19:21.073" LastActivityDate="2014-03-09T17:19:21.073" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2137" PostTypeId="2" ParentId="2135" CreationDate="2014-03-09T15:00:30.727" Score="18" Body="&lt;p&gt;High windspeeds themselves are not a problem, but the environment surrounding them may be.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in the wintertime it is not uncommon to find a strong core of fast winds embedded within the polar jetstream.  We term this windspeed maximum a 'jet streak'.  There are a couple of meteorological phenomena associated around these jetstreaks, such as regions of ascent and descent in the entrance and exit regions of the jetstreak and often times turbulence in the periphery.  You'll also find regions of turbulence on the lateral extent of the jetstream (polar side in particular).  Lastly, if you are flying at an angle to the jetstream or perpendicular to it, you will often experience changing wind direction along with speed, and this can be turbulent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is nothing dangerous about that wind speed alone.  What likely happened is that other airplanes were reporting turbulence and the pilots were being cautious with you and just offered that wind speed up as an easily understood number to justify the precaution.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="5562" LastEditDate="2015-04-08T09:48:00.760" LastActivityDate="2015-04-08T09:48:00.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2138" PostTypeId="1" AcceptedAnswerId="2139" CreationDate="2014-03-09T16:39:39.603" Score="9" ViewCount="2012" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/SOCATA_TB_family&quot;&gt;Socata TB-family wikipage&lt;/a&gt; lists the TB-9 and TB-10 as having &quot;spatted undercarriage&quot;. What does that mean? From the pictures it appears to be a normal tricycle-gear-setup so I assume it's not referring to the layout of the landing gear.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2019-01-05T20:26:03.553" Title="What is &quot;spatted undercarriage&quot;?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2139" PostTypeId="2" ParentId="2138" CreationDate="2014-03-09T16:48:25.107" Score="13" Body="&lt;p&gt;If I'm not mistaken, a &lt;strong&gt;spat is a fairing for the gear&lt;/strong&gt; to make it more aerodynamic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xas5P.jpg&quot; alt=&quot;spat&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft wheel fairing, commonly called a wheel pant or spat or, by&#xA;  some manufacturers, a speed fairing. &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_fairing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-05T20:26:03.553" LastActivityDate="2019-01-05T20:26:03.553" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2140" PostTypeId="2" ParentId="2138" CreationDate="2014-03-09T17:43:19.173" Score="11" Body="&lt;p&gt;&quot;Spatted undercarriage&quot; refers to &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_fairing&quot; rel=&quot;noreferrer&quot;&gt;streamlined fairings&lt;/a&gt; on fixed landing gear&lt;/strong&gt;. They're also known as &lt;strong&gt;&quot;wheel pants&quot;&lt;/strong&gt;, although when it comes to comparisons with clothing &lt;strong&gt;&quot;spats&quot;&lt;/strong&gt; is certainly more accurate, as they only cover the top of the wheel, not the entire gear leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term is semi-common in the US, but I've mostly heard (and used) &quot;wheel pants&quot; when talking about landing gear fairings.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Spats / wheel pants / fairings on an AA-1's landing gear:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/File:AmericanAviationAA-1YankeeWheelFairing.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c8c3Um.jpg&quot; alt=&quot;spats on an airplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Spats on shoes on Charles Sumner:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/File:Sumner-Longfellow_crop.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tw0Esm.jpg&quot; alt=&quot;spats on sumner&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-09T17:50:46.013" LastActivityDate="2014-03-09T17:50:46.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2141" PostTypeId="1" AcceptedAnswerId="2156" CreationDate="2014-03-09T18:19:37.190" Score="13" ViewCount="3353" Body="&lt;p&gt;I'm in the process of getting my private pilot's license, and I've come to the point where it's probably time to think about buying a headset. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it there are a few options ranging from a standard mic and speakers, to passive noise cancellation, active noise cancellation, and even bluetooth for use with iPhones/MP3 players, which I think is awesome, however I'm concerned about distraction while flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has listening to music and/or noise cancellation been at all shown to increase pilot error?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My main concerns are&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What if I have a noise cancelling headset on, and the engine undergoes detonation, or what if the aircraft does something I should be alarmed about based on auditory cues that I can't hear?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Same situations as above, but even worse because I'm rocking out to some sweet tunes, is there the possibility that having music will exacerbate the aforementioned issues, or what if ATC comes on, and I hear them, but I don't register what they say because I was jamming to some Kenny Loggins?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Additionally, are commercial pilots permitted to use bluetooth headsets for phone calls? For music? Do crash statistics indicate that music and flying leads to more pilot-error? It certainly can't help...&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="43" LastEditDate="2014-03-10T12:33:29.047" LastActivityDate="2014-03-10T16:20:22.133" Title="Do bluetooth aviation headsets and/or music negatively affect safety?" Tags="&lt;safety&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2142" PostTypeId="2" ParentId="2141" CreationDate="2014-03-09T22:44:15.577" Score="11" Body="&lt;p&gt;Let me share some of my experiences with my active noise cancelling headset when flying piston aeroplanes. First, if you fly multi-engine and the props are not synchronizing automatically everyone without active noise cancelling on board will definitely hate you - you really don't hear that horrible sound which is really comfortable especially while practicing engine failures. Beside of this you are still able to hear everything whats going on. It there are abrupt noises or warning horns you'll be able to hear them. Active noise cancelling can really help you to be concentrated and allows you to hear ATC much clearer than before. This is especially valuable on crowded frequencies or while getting an ATIS, but also being under radar control/services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Listening to music while flying is a different story. It can be distracting and I'm still cautious using this great feature. On long x- countries it's really amazing to have it while I would for sure turn it off approaching a busy airport. It can definitely influence your ability to focus on the flight, but sometimes I think even on a positive way keeping you in a good mood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best you can do is to try it, because everyone is different. Find the best settings for your self and make your own experiences. There are aviation shops which will give you a headset to try it, otherwise you can ask friends who may have one, or order via the internet and if you don't really feel comfortable with the one you ordered you can return it during a specified period of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last and really important point: If you tested it and decided to spend some extra money on a high-end headset look for special offers. There are a bunch of websites where you can safe a lot of money. I would always check if you still have the original guarantee.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-03-10T06:36:03.533" LastActivityDate="2014-03-10T06:36:03.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2143" PostTypeId="1" AcceptedAnswerId="2144" CreationDate="2014-03-10T02:03:45.887" Score="11" ViewCount="1718" Body="&lt;p&gt;I was looking through my ADSB Virtual Radar outputs couple days ago and saw a weird re-route for one of the aircraft that looked out of place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can one of the pilots/ATC guys pitch in to help me understand what may have caused this A/C to do this?  Is this &quot;normal&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would expect if this was a wake turbulence from A/C ahead they would have just asked the rerouting A/C to just slow down?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail #: N39463&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://imgur.com/GYK2caA.jpg&quot; alt=&quot;&quot; title=&quot;KORD interesting re-route&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="247" LastEditDate="2014-03-12T09:42:30.667" LastActivityDate="2014-03-12T09:42:30.667" Title="Why did this aircraft re-route?" Tags="&lt;air-traffic-control&gt;&lt;approach&gt;&lt;ads-b&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2144" PostTypeId="2" ParentId="2143" CreationDate="2014-03-10T02:10:21.793" Score="14" Body="&lt;p&gt;Its hard to tell from the picture, but assuming you are talking about the yellow airplane and the &quot;wiggle&quot; in the course, that was probably just an S-turn for spacing.  Sometimes the controllers don't get the spacing exactly right, or one airplane slows down early and messes things up.  In those cases, in visual conditions,  the controller can ask the following airplane to make an S-turn.  This causes the plane to take a bit more time to cover the same distance as flying straight and spaces the planes out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may be used instead of a speed assignment for a number of reasons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Planes on approach may not be able to slow down further as configured&lt;/li&gt;&#xA;&lt;li&gt;There may already be a speed assignment but it wasn't enough&lt;/li&gt;&#xA;&lt;li&gt;Slowing down takes time, and S turn may be more efficient.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An ATC instruction may assign a heading and follow up with a new heading and approach clearance or other instructions to join final, or they may simply ask for an &quot;S turn to the right for spacing&quot;.  The vectors would be more likely in instrument conditions and the S-turn more likely in visual conditions.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-10T02:19:59.923" LastActivityDate="2014-03-10T02:19:59.923" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2145" PostTypeId="2" ParentId="2013" CreationDate="2014-03-10T03:13:36.237" Score="6" Body="&lt;p&gt;The FAA has a document on their website which breaks knowledge tests down by FSDO rather than state, and it gives a good idea of where the most training is taking place.&lt;/p&gt;&#xA;&lt;p&gt;It is called: &lt;a href=&quot;http://www.faa.gov/data_research/aviation_data_statistics/test_statistics/media/2013/annual/2013_Airmen_Knowledge_Tests_by_Region_and_FSDO.pdf&quot; rel=&quot;noreferrer&quot;&gt;2013 Airmen Knowledge Tests by Region and FSDO&lt;/a&gt;, and lists the following Regions/FSDO's as processing the most knowledge tests (in descending order)&lt;sup&gt;1&lt;/sup&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Southern 28,333&lt;/strong&gt;&lt;br /&gt;&#xA;Orlando 9,996&lt;br /&gt;&#xA;South Florida 5,958&lt;br /&gt;&#xA;Alabama &amp;amp; NW Florida 4,680&lt;br /&gt;&#xA;Atlanta 3,882&lt;br /&gt;&#xA;Tampa 2,504&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Western Pacific 18,416&lt;/strong&gt;&lt;br /&gt;&#xA;Scottsdale 6,053&lt;br /&gt;&#xA;Riverside 1,556&lt;br /&gt;&#xA;San Diego 1,463&lt;br /&gt;&#xA;Sacramento 1,460&lt;br /&gt;&#xA;Long Beach 1,327&lt;br /&gt;&#xA;Fresno 1,270&lt;br /&gt;&#xA;Los Angeles 1,142&lt;br /&gt;&#xA;San Jose 1,121&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Southwest 15,943&lt;/strong&gt;&lt;br /&gt;&#xA;Dallas 2,731&lt;br /&gt;&#xA;Fort Worth 2,581&lt;br /&gt;&#xA;Houston 2,438&lt;br /&gt;&#xA;Oklahoma City 2,347&lt;br /&gt;&#xA;San Antonio 2,321&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Eastern 14,552&lt;/strong&gt;&lt;br /&gt;&#xA;Richmond 1,956&lt;br /&gt;&#xA;Greensboro 1,366&lt;br /&gt;&#xA;Farmingdale 1,280&lt;br /&gt;&#xA;Philadelphia 1,198&lt;br /&gt;&#xA;New York City 1,069&lt;br /&gt;&#xA;Boston 1,041&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Great Lakes 11,860&lt;/strong&gt;&lt;br /&gt;&#xA;Fargo 2,120&lt;br /&gt;&#xA;Dupage 1,414&lt;br /&gt;&#xA;Indianapolis 1,358&lt;br /&gt;&#xA;Minneapolis 1,142&lt;br /&gt;&#xA;East Michigan 1,111&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Northwest Mountain 9,784&lt;/strong&gt;&lt;br /&gt;&#xA;Denver 2,205&lt;br /&gt;&#xA;Portland 2,131&lt;br /&gt;&#xA;Salt Lake City 1,964&lt;br /&gt;&#xA;Seattle 1,611&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Central 9,019&lt;/strong&gt;&lt;br /&gt;&#xA;Nashville 4,293&lt;br /&gt;&#xA;Wichita 1,304&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Alaskan 812&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Based on this data, I would say that the areas surrounding the Orlando, Scottsdale, South Florida, Alabama &amp;amp; NW Florida, Nashville, and Atlanta FSDO's are the most popular training areas, with the Southern region being the most popular by far.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; To improve readability, all FSDO's with less than 1,000 tests have been removed.  See the source data for the complete list.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-10T04:22:36.297" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2146" PostTypeId="1" AcceptedAnswerId="2158" CreationDate="2014-03-10T03:33:41.777" Score="7" ViewCount="5444" Body="&lt;p&gt;14 CFR 121 and 135 certificate holders are required to maintain operational control of their flight operations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=6aa7b1b0b35ca9f042f3c20dee29b2c0&amp;amp;node=14:3.0.1.1.11.2.3.11&amp;amp;rgn=div8&quot;&gt;&lt;strong&gt;§135.77   Responsibility for operational control.&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;Each certificate holder is responsible for operational control and shall list, in the manual required by §135.21, the name and title of each person authorized by it to exercise operational control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d8b7ff2b5cc7f33e7e7f97975d3dccbd&amp;amp;node=14:3.0.1.1.7.20.3.2&amp;amp;rgn=div8&quot;&gt;121.533&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d8b7ff2b5cc7f33e7e7f97975d3dccbd&amp;amp;node=14:3.0.1.1.7.20.3.3&amp;amp;rgn=div8&quot;&gt;121.535&lt;/a&gt;, and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d8b7ff2b5cc7f33e7e7f97975d3dccbd&amp;amp;node=14:3.0.1.1.7.20.3.4&amp;amp;rgn=div8&quot;&gt;121.537&lt;/a&gt; contain similar requirements for 121 carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is &quot;Operational Control&quot;?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-10T19:09:00.717" Title="What is &quot;Operational Control&quot;?" Tags="&lt;far-135&gt;&lt;far-121&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2147" PostTypeId="1" CreationDate="2014-03-10T04:54:15.840" Score="2" ViewCount="1636" Body="&lt;p&gt;I'm new to aviation but I am very passionate about it. I'm just 14 years old, so please help me in finding a good e-book about aviation for free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how to search with Google about it.&lt;/p&gt;&#xA;" OwnerUserId="1336" LastEditorUserId="774" LastEditDate="2014-03-10T14:13:46.303" LastActivityDate="2018-02-22T16:41:21.210" Title="Aviation ebook for beginners?" Tags="&lt;website&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ClosedDate="2014-03-10T23:07:32.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="2149" PostTypeId="1" AcceptedAnswerId="2151" CreationDate="2014-03-10T05:59:56.330" Score="13" ViewCount="842" Body="&lt;p&gt;The case of &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;nofollow&quot;&gt;the lost Malaysian Airlines plane&lt;/a&gt; is tragic for all those involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of such a plane lost over the ocean, hypothetically (and described very simplistically), it would seem that the fastest way to search for wreckage would be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;to define an area to be searched&lt;/li&gt;&#xA;&lt;li&gt;wait for the latest satellite images for that area at high-resolution to be available (given appropriate positioning and programming of the satellites)&lt;/li&gt;&#xA;&lt;li&gt;then search the captured imagery for deviations from ocean blue&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Presumably this could be done reasonably quickly by a computer, and that satellite imagery is taken after a suspected crash, and exceptions (e.g. spots of white amongst the blue) are able to be verified by a human.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does such a system exist? Are imaging satellites able to be configured to take such imagery on demand over a large area? And do such batch-image processing systems exist for this purpose?&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="97" LastEditDate="2015-05-03T01:54:51.137" LastActivityDate="2015-05-03T01:54:51.137" Title="Does a system exist that can bulk process satellite data to find a plane lost over ocean?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;&lt;software&gt;&lt;mh370-incident&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2150" PostTypeId="2" ParentId="2147" CreationDate="2014-03-10T08:13:59.240" Score="1" Body="&lt;p&gt;Aviation is a pretty complicated topic and can get very overwhelming very quickly, so it's not easy to locate something specifically. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;eBooks however are not too easy to find, since you'll get the full load of manuals and regulatory documents in the search. You might find something (including the ordinary print books below) by searching for &lt;code&gt;book_name filetype:pdf&lt;/code&gt; in google. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you're out for a good reference book, something like Anderson's &lt;em&gt;Introduction to Flight&lt;/em&gt; will be good, but bear in mind this is hardly an easy read but does cover virtually everything you will need to know. An &lt;a href=&quot;http://ae.sharif.edu/~iae/Download/Introduction%20to%20flight.pdf&quot; rel=&quot;nofollow&quot;&gt;older edition&lt;/a&gt; seems to be available online.&lt;/li&gt;&#xA;&lt;li&gt;There are plenty of books on flight simulation, which is often a great place to start. A fantastic one I picked up with lots of facts and stuff was &lt;em&gt;Flight Simulator X for Pilots&lt;/em&gt; written by Van West and Lane-Cummings. This covers everything from navigations, maps and handling the aircraft. There are a lot of similar stuff on websites and youtube as well.&lt;/li&gt;&#xA;&lt;li&gt;There are plenty of websites on model aircraft building and drones. Less theory and more practise, but anyway interesting and educational.&lt;/li&gt;&#xA;&lt;li&gt;There are plenty of pilot blogs around, where you can read lots of good stuff.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I could also suggest that you join the edX &lt;strong&gt;free online course given by Delft University of Technology in &lt;a href=&quot;https://www.edx.org/course/delftx/delftx-ae1110x-introduction-aeronautical-1201&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Engineering&lt;/a&gt;&lt;/strong&gt;. You get a certificate at the end as well if I'm not wrong, and it should give you a decent introduction if you're able to keep up with it :) Top 20 technical university and the largest faculty in Europe.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-10T09:16:23.837" LastActivityDate="2014-03-10T09:16:23.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2151" PostTypeId="2" ParentId="2149" CreationDate="2014-03-10T08:30:02.640" Score="10" Body="&lt;p&gt;&lt;strong&gt;Update: Satellites were eventually used in the search for MA370, see &lt;a href=&quot;http://www.scmp.com/news/china/article/1445698/10-chinese-satellites-deployed-search-missing-plane&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt;.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This question might be better answered by the &lt;a href=&quot;https://space.stackexchange.com/&quot;&gt;folks at space exploration&lt;/a&gt; but here's a shot:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Oil slicks are not uncommon at sea, so finding one from the aircraft is not too easy.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's an incredibly large area pulling a lot of processing power. You're going to need pretty good resolution imagery over several square kilometers and then run image recognition on it. Look at this image which has a scale of 25 miles which is still a fraction of what you would need to get an idea:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://1.bp.blogspot.com/-1VKvB3LWSVY/TsvjgPhD5nI/AAAAAAAAAAo/ET_z9-6jvFc/s1600/SkyTruth-Campos-oilspill-ASAR_22nov2011.jpg&quot; alt=&quot;sat&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The fragments you're looking for are very small in regards to waves. I suspect depending on where you are there's a large amount of noise from other rubbish which is hard to filter out, such as a white plastic sheet to a door. You might even go confusing big aircraft parts to other white boats. Yes, you can continue the search but it takes time to go through all of these and dismiss them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A lot of volunteers searched for Steve Fossett when he went missing, and there was some attempts to locate him by satellite imagery from google maps, which was not successful.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft, while not fast, can be over the side within a few hours, while I think you have to wait until the satellites have caught all the imagery you would like.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While I think it could be done as you say, you would need to develop software and I don't think the market for it exists, but that's just my guess. Reading up it appears that satellites are used against drug cartels along the USA-Mexico border and against illegal immigrants elsewhere in the world.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-04-13T12:58:55.350" LastActivityDate="2014-03-10T22:20:27.393" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2152" PostTypeId="2" ParentId="2147" CreationDate="2014-03-10T09:17:06.803" Score="8" Body="&lt;p&gt;Although this is a question based on opinion, it might perhaps have some value as a community wiki so I've marked this 'answer' as such. I also borrowed one of Manfred's links. Feel free to append stuff to the list.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In terms of free download, I can definitely recommend the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Airplane Flying Handbook&lt;/a&gt; which can be found on the FAA web site. There are also a number of other handbooks there which are great reads. To be honest, I find this the best introductory book I know, free or otherwise.&lt;/li&gt;&#xA;&lt;li&gt;If you're out for a good reference book, something like Anderson's &lt;em&gt;Introduction to Flight&lt;/em&gt; will be good, but bear in mind this is hardly an easy read but does cover virtually everything you will need to know. An &lt;a href=&quot;http://ae.sharif.edu/~iae/Download/Introduction%20to%20flight.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;older edition&lt;/a&gt; seems to be available online.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2" LastEditorUserId="8114" LastEditDate="2018-02-22T16:41:21.210" LastActivityDate="2018-02-22T16:41:21.210" CommentCount="2" CommunityOwnedDate="2014-03-10T09:17:06.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="2153" PostTypeId="1" AcceptedAnswerId="2155" CreationDate="2014-03-10T13:09:43.190" Score="43" ViewCount="13471" Body="&lt;p&gt;In a &lt;a href=&quot;http://www.bbc.com/news/world-asia-26513506&quot; rel=&quot;noreferrer&quot;&gt;recent BBC article&lt;/a&gt; regarding the disappearance of Malaysian Airlines Flight 370 (MH-370), the writer refers to a US Naval officer's statement:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Commander William Marks from the US Seventh Fleet, which is taking part in the search, says he expects the plane's flight recorders to be floating in the water.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;In calm seas, if there were a soccer ball [football] or a basketball floating in the water, the radar could pick it up. They [flight recorders] typically have a radio beacon and so for example our P3 [radar] - if they are flying within a certain range of that - will pick up that radio beacon. We have not yet picked up anything, but that's typically what those black boxes contain.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I was under the (potentially incorrect) impression that flight recorders, by nature of the materials needed to protect their contents in the event of a crash, are quite dense and unable to float in water. I base this impression on news reporting of other airliner crashes (such as Air France 447, which crashed in the Atlantic), where the recorders were found some time later on the ocean floor.&lt;/p&gt;&#xA;&lt;p&gt;Additionally, it seems reasonable to me that one would want to have the recorders &lt;em&gt;not&lt;/em&gt; float so that they would come to rest near the other debris on the ocean floor since the recorders are equipped with underwater locator beacons which would aid in locating not only the recorders themselves but also the debris of the plane. If the recorders floated then they could move significant distances from the crash site and other debris, complicating search efforts.&lt;/p&gt;&#xA;&lt;p&gt;It seems that Commander Marks, the writer of the article, or I (or some combination thereof) misunderstand something about flight recorders and their behavior in water.&lt;/p&gt;&#xA;&lt;p&gt;My questions are these:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Do flight recorders float on water? If so, why?&lt;/li&gt;&#xA;&lt;li&gt;I know that flight recorders are equipped with underwater locator beacons. Are they also equipped with radio beacons (either an active transmitter or a some passive device like a corner reflector to make them easier to detect with radar)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: The article has been updated, with the section regarding floating data recorders now reading:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Commander William Marks from the US Seventh Fleet, which is taking part in the search, said he expected the plane's flight recorders to be floating in the water.&lt;/p&gt;&#xA;&lt;p&gt;He said the recorders, also known as &amp;quot;black boxes&amp;quot;, are fitted with radio beacons that can be picked up by radar.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1338" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-04-17T21:37:13.753" Title="Do flight recorders float in water?" Tags="&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2154" PostTypeId="2" ParentId="2149" CreationDate="2014-03-10T13:29:32.963" Score="9" Body="&lt;p&gt;Massive area, large search interval, no complete coverage of the entire area, especially no permanent coverage of the entire area, weather, limited computer power. &lt;br/&gt;&#xA;All those factors, each on their own, would make the problem massive. Taken together they make it insurmountable.&lt;br/&gt;&#xA;We're talking an area of several million square kilometers that needs to be searched, at a resolution of a few square meters, over an interval of several hours.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Not only is there no 24/7 photographic coverage at that resolution available of any spot on the planet, it certainly won't exist of a stretch of open ocean in a backwater of geopolitical interest (it MIGHT exist just around the time of a drone strike on a Taliban compound for example, over an area of a few hundred meter around that compound, for maybe 10 minutes prior to 10 minutes past, but that data would be highly classified for obvious reasons and utterly useless unless an airliner crashed right on top of that compound during that small window).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Manfred hints that satellite coverage is used against drugs and human trafficking and it may be. But it can't detect individual human beings. It CAN potentially detect patterns, like finding paths through brushland that from the ground can't be easily seen but from the air show up. And in case of anti-trafficking use, it mainly is used to surveil known or suspected points of departure, say an airfield in Colombia known to be used by drugs smugglers, and alert law enforcement agencies of a possible inbound aircraft which can then be tracked using other means (like AWACS) and intercepted. Same with boats. But it's not real time, it's photos taken at several hour intervals of known &quot;points of interest&quot;.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;We simply lack the resolution to see something the size of a human being (or a floating piece of aircraft debris like a toilet seat or life jacket) from orbit.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Oil slicks, which tend to spread out a lot, can be observed and investigators sent to the area. This is used in coastal regions to find and fine ships that illegally dump oil from their balast tanks. But again, there's no permanent coverage and certainly not over open ocean. Maybe some country with the capability can redirect one of its satellites after the suspected crash, and hopefully when it gets there it's not too late (dispersal is rapid) AND the weather is clear AND there's daylight AND everything else falls into place.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;No, the best hope is narrowing down the area based on last radio or radar reporting position, and do an area search from there. And if you get real lucky you get a responder in the FDR or CVR to give you a beep, or an emergency beacon in a life raft that got shook loose and turned itself. Other than that, fingers crossed that someone with a pair of binoculars spots something floating out there before it's all sunk to the bottom.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-10T13:29:32.963" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2155" PostTypeId="2" ParentId="2153" CreationDate="2014-03-10T14:51:41.170" Score="34" Body="&lt;p&gt;You are correct in the assumption that the typical data recorders being used today are too heavy to float.   They are designed to withstand &lt;strong&gt;very&lt;/strong&gt; high forces, extreme temperatures, and to withstand corrosive environments (like sea water) for long periods of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avbuyer.com/articles/detail.asp?Id=1858&quot;&gt;For example&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A DFDR must obviously have a high degree of ‘crashworthiness.’ The&#xA;  first units were required to withstand a momentary shock force of&#xA;  1,000gs, the latest test standards now call for a test to 3,400gs for&#xA;  a duration of 6.5 milliseconds. The units also have to withstand a&#xA;  static crushing force at all of its six axis points of an applied load&#xA;  force of 5,000lbs for 5 minutes on each axis. Third, it must withstand&#xA;  a 500lbs piercing force test conducted by dropping it onto a ¼ inch&#xA;  steel pin from 10 feet. Lastly it must withstand a 1,100°C fire test&#xA;  for 60 minutes, and a 260°C oven test for 10 hours. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It is also required that these units are mounted within the tail area&#xA;  of an aircraft, away from the potential crushing force of any engines&#xA;  mounted nearby. The DFDR must be watertight to a depth of 20,000 feet&#xA;  in sea water, and survive at this depth for 30 days - and it must be&#xA;  fitted with an underwater locator beacon which will act like a sonar&#xA;  transmitter, by ‘pinging’ a signal through the medium of water that it&#xA;  might be laying in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Time has an &lt;a href=&quot;http://content.time.com/time/photogallery/0,29307,1903392_2272140,00.html&quot;&gt;article&lt;/a&gt; showing the Air France 447 flight data recorders resting on the bottom of the ocean (there are others there):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o4QUOm.jpg&quot; alt=&quot;FDR image 1&quot;&gt;  &lt;img src=&quot;https://i.stack.imgur.com/GorHpm.jpg&quot; alt=&quot;FDR image 2&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This particular FDR is pretty common, and weighs about 13.5 pounds&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without seeing the original interview, I suspect that the author of the article got confused during the interview and was told that radar could detect debris the size of a soccer ball that is floating in the water and at a different time mentioned that they would be looking for the radio signals emitted by the black box (which wouldn't even be detected by radar).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, there &lt;strong&gt;are&lt;/strong&gt; black boxes that can float and even eject from the airplane when a crash is detected.  They seem to be more common in military aircraft, and there have been a few attempts to require them in the US (and even have the government pay the $60,000/airplane price) but the bills stalled in congress.  The lawmakers here have recently started discussing this again though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Deployable Black Boxes&lt;/em&gt; have been around since the 60's and are a second set of black boxes meant to be a backup to the main ones.  They can be particularly useful when crashing into water or in the event of a major fire because they would not be within the main crash site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.defensemedianetwork.com/wp-content/uploads/2011/06/wings-dfirs-web.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JPC8B.jpg&quot; alt=&quot;Deployable Black Box Photo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a couple of articles about them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.securitymagazine.com/articles/85331-lawmaker-calls-for-black-boxes-that-eject-from-planes&quot;&gt;Lawmaker Calls for 'Black Boxes' that Eject from Planes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.mywebmemo.com/business/canada-s-deployable-recorder-would-have-located-missing-airliner_139977.html&quot;&gt;Canada’s ‘deployable recorder’ would have located missing airliner within minutes, experts say&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; See specifications on &lt;a href=&quot;https://commerce.honeywell.com/webapp/wcs/stores/servlet/EProductDisplay?storeId=10651&amp;amp;productId=357986&amp;amp;langId=-1&amp;amp;cacheId=1000000000000001&quot;&gt;Honeywell's webpage&lt;/a&gt; and page 7 of their &lt;a href=&quot;http://visualjournalism.com/wp-content/uploads/Flight_Data_Recorder_%28SSFDR%29.pdf&quot;&gt;product description&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="65" LastEditDate="2015-01-08T14:23:43.700" LastActivityDate="2015-01-08T14:23:43.700" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2156" PostTypeId="2" ParentId="2141" CreationDate="2014-03-10T16:20:22.133" Score="13" Body="&lt;p&gt;To my knowledge there are no studies correlating ANR (or good quality passive) headsets with an increase in pilot error, but a several have been done on &lt;a href=&quot;http://en.wikipedia.org/wiki/Listener_fatigue&quot;&gt;noise fatigue&lt;/a&gt;. There's even &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23154&quot;&gt;an &lt;em&gt;old&lt;/em&gt; FAA advisory circular on the subject&lt;/a&gt; which basically boils down to &quot;Multi-hour flights listening to the engines drone on and on will make the pilot cranky and error-prone&quot;  - so from that perspective any good-quality headset is a safety enhancement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as missing auditory cues because of ANR (things like the stall warning, funny engine noises, etc.) it's generally not a concern: ANR headsets are good, but they're not THAT good. Because of the way ANR works sudden sounds will cut through. You'll miss &quot;long-term noise&quot; (like the beat frequencies Falk mentioned from unsynchronized propellers), but you're not likely to miss anything safety-critical.&lt;br&gt;&#xA;(One notable exception: ANR headsets are good at cutting out wind noise, so if you have a partially unlatched door you won't hear that.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you will notice with ANR headsets is that when the battery dies things get loud - sometimes louder than cheap passive headsets. Carrying extra batteries is a must with ANR headsets since having your noise reduction go away in the middle of a flight would be somewhat unpleasant.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as music, that's a mixed bag.  Much like having a CD playing in your car, I don't believe it's a significant safety impact unless you're being irresponsible with it (blasting it at a volume that drowns out everything around you, or rocking out when you should be watching for traffic).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, all the intercoms and headsets I've seen give the com radio priority, and will either cut out or substantially mute the music input when there's radio traffic.  This makes you less likely to miss radio calls, but it also makes listening to music in the plane an absolutely DREADFUL experience (in the northeast where I am there's always &lt;strong&gt;&lt;em&gt;somebody&lt;/em&gt;&lt;/strong&gt; talking on the frequency - if you hear half of the song between the radio cutting in it's a good day).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I personally find the distraction from the music muting/unmuting to be more of an issue than boredom from not having music in the first place (if you're that bored you can always &lt;em&gt;look out the window&lt;/em&gt;, or tune a local CTAF frequency and listen to the antics), but your experience may vary substantially if you're in an area where the radio is quieter.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Policies for commercial pilots would vary depending on the operation, but for airline pilots &lt;a href=&quot;http://news.cnet.com/8301-1035_3-57618756-94/faa-bans-pilots-personal-use-of-electronic-devices-in-cockpit/&quot;&gt;using your personal cell phone is forbidden&lt;/a&gt;, and before it was forbidden by the FAA it was usually prohibited by the airline.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 91 operations (a ferry flight, or a crop duster spraying the local fields) wouldn't be subject to that restriction though, and making a phone call or listening to music would be permissible under the FARs. With all the studies on the negative safety effects of using a cell phone while driving I wouldn't recommend the phone call, but I imagine crop dusting is more fun if you have some music to listen to…&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-10T16:20:22.133" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2157" PostTypeId="2" ParentId="2147" CreationDate="2014-03-10T17:01:09.580" Score="0" Body="&lt;p&gt;Sporty's ground school course is pretty helpful, you can get it for free if you can get yourself on an EAA Young Eagles flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I am not sure about ebooks, but you can find copies of these books on eBay or Amazon.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;As the Pro Flies (John R. Hoyt)&lt;/li&gt;&#xA;&lt;li&gt;Stick and Rudder (Wolfgang Langewiesche)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;General interesting aviation books&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Janes All the World's Aircraft&lt;/li&gt;&#xA;&lt;li&gt;Janes Aircraft Recognition Guide&lt;/li&gt;&#xA;&lt;li&gt;A Field Guide to Airplanes, Third Edition (M. R. Montgomery)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-10T17:01:09.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2158" PostTypeId="2" ParentId="2146" CreationDate="2014-03-10T19:02:48.240" Score="4" Body="&lt;p&gt;Operational control is defined in &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.3,Ch25,Sec1&quot; rel=&quot;nofollow&quot;&gt;8900.1 Volume 3, Chapter 25&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Operational control functions include, but are not limited to:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Preflight planning;&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, preparation and dissemination of dispatch/flight releases;&lt;/li&gt;&#xA;  &lt;li&gt;Canceling a flight due to potential hazardous or unsafe conditions;&lt;/li&gt;&#xA;  &lt;li&gt;Ensuring that only those operations authorized by the OpSpecs are conducted;&lt;/li&gt;&#xA;  &lt;li&gt;Ensuring that only crewmembers who are trained and qualified in accordance with the applicable regulations are assigned to conduct a flight;&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, ensuring that no flight is started unless it has been authorized by a dispatcher or person authorized to exercise operational control in accordance with §§ 121.593, 121.595, or 121.597, as applicable;&lt;/li&gt;&#xA;  &lt;li&gt;Ensuring that crewmembers are in compliance with flight and duty time limitations and rest requirements prior to departing on a flight;&lt;/li&gt;&#xA;  &lt;li&gt;Designating a pilot in command (PIC) and, where applicable, a second in command (SIC) for each flight;&lt;/li&gt;&#xA;  &lt;li&gt;Providing the personnel who perform operational control functions (PIC, dispatcher, etc.) with access to all necessary information for the safe conduct of the flight (for example, weather, Notices to Airmen (NOTAM), airport aeronautical data (analysis), and inoperable instruments and equipment);&lt;/li&gt;&#xA;  &lt;li&gt;Specifying the conditions under which a flight may be dispatched or released (weather minimums, flight planning, airworthiness of aircraft, aircraft loading, and fuel requirements);&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, ensuring that when the conditions, limitations, and authorizations specified in a dispatch or flight release cannot be met, the flight is either cancelled, delayed, rerouted, or diverted;&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, ensuring that each flight is conducted in accordance with the conditions and limitations of the dispatch or flight release;&lt;/li&gt;&#xA;  &lt;li&gt;Ensuring that each flight is operated in accordance with the limitations of the MEL and CDL;&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, monitoring the progress of each flight and initiating timely actions when the flight cannot be completed as planned, including diverting or terminating a flight;&lt;/li&gt;&#xA;  &lt;li&gt;For part 135 operations, locating a flight for which a Federal Aviation Administration (FAA) flight plan (FP) has not been filed;&lt;/li&gt;&#xA;  &lt;li&gt;For part 121 operations, ensuring rapid and reliable communications in accordance with §§ 121.99 and 121.122, as applicable;&lt;/li&gt;&#xA;  &lt;li&gt;Restricting or suspending operations in accordance with §§ 121.551, 121.553, or 135.69 as applicable; and&lt;/li&gt;&#xA;  &lt;li&gt;Exercising the emergency authority described in §§ 121.557, 121.559, and 135.19, as applicable.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These functions are normally performed by a variety of people:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Dispatch&lt;/li&gt;&#xA;&lt;li&gt;Crew Scheduling&lt;/li&gt;&#xA;&lt;li&gt;Maintenance &lt;/li&gt;&#xA;&lt;li&gt;Chief Pilots&lt;/li&gt;&#xA;&lt;li&gt;Director of Operations&lt;/li&gt;&#xA;&lt;li&gt;The PIC of the flight&lt;/li&gt;&#xA;&lt;li&gt;Manager of SOCC (System Ops Control Center)&lt;/li&gt;&#xA;&lt;li&gt;Director of Training&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Operational control is implemented by the above people and must hit all of the bullets in the definition above.  This means that to exercise operational control you must always know where your planes are, you must determine who flies them, plan those flights, ensure the pilots and aircraft are legal, ensure everyone is trained for the operations performed and to always be able to communicate with your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also mention of Operational Control Systems, which require that any flight operated by the carrier is dispatched, followed and can be located at all times.  These functions are normally carried out by the Dispatcher assigned to your flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further reading beyond the 8900.1 can be found in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/305074&quot; rel=&quot;nofollow&quot;&gt;AC 120-101&lt;/a&gt; for 121 ops.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-10T19:09:00.717" LastActivityDate="2014-03-10T19:09:00.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2159" PostTypeId="1" AcceptedAnswerId="2180" CreationDate="2014-03-10T23:46:59.583" Score="1" ViewCount="2121" Body="&lt;p&gt;In a flight database that I'm working with on a project, there is a column of data called &quot;flightCategory&quot; with values &quot;C&quot;, &quot;G&quot;, &quot;T&quot;, etc.  Any idea what those actually mean?  From what I understand, the database is from FAA.  But I'm not 100% sure.&lt;/p&gt;&#xA;" OwnerUserId="1349" LastEditorUserId="1349" LastEditDate="2014-10-03T23:18:33.090" LastActivityDate="2014-10-03T23:19:17.763" Title="What does flight categories &quot;C&quot;, &quot;G&quot;, &quot;T&quot; etc. mean?" Tags="&lt;faa-regulations&gt;&lt;flight-data-recorder&gt;&lt;software&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2014-08-19T08:57:39.853" ContentLicense="CC BY-SA 3.0" />
  <row Id="2160" PostTypeId="1" AcceptedAnswerId="2161" CreationDate="2014-03-11T02:09:03.647" Score="28" ViewCount="16364" Body="&lt;p&gt;I was speaking to someone about the &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;nofollow&quot;&gt;MH370 incident&lt;/a&gt;, and they suggested that a hijacker could turn off the device that sends the plane's current position, resulting in the appearance of a catastrophic midair failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that such functionality could not be turned off, but I could be wrong. Is there any way that this could be done? Could an aircraft's internal tracking systems be &quot;turned off&quot; midair, and also not be located by external tracking like radar?&lt;/p&gt;&#xA;" OwnerUserId="1351" LastEditorUserId="247" LastEditDate="2014-06-22T12:19:37.767" LastActivityDate="2018-12-22T01:28:09.077" Title="Is it possible for a modern commercial airliner to stop being tracked without substantial mechanical failure?" Tags="&lt;avionics&gt;&lt;radar&gt;&lt;mh370-incident&gt;&lt;gnss&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2161" PostTypeId="2" ParentId="2160" CreationDate="2014-03-11T02:21:42.997" Score="22" Body="&lt;p&gt;The device you are talking about is called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_%28aeronautics%29&quot; rel=&quot;nofollow&quot;&gt;transponder&lt;/a&gt;.  This is a device that listens for a signal (an interrogation) and responds with information about the airplane including an ATC assigned code, altitude information and additional aircraft info for certain equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 2 ways ATC watches airplanes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Secondary_surveillance_radar#Primary_radar&quot; rel=&quot;nofollow&quot;&gt;Primary Radar&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Secondary_surveillance_radar#Secondary_radar&quot; rel=&quot;nofollow&quot;&gt;Secondary Surveillance Radar&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The transponder is interrogated by the Secondary radar and the response is listened for.  Even with no transponder, the aircraft can still be tracked by primary radar.  This is just a normal radar that is good at seeing airplane sized objects and not so great at seeing weather and can occasionally spot a large flock of birds.  The primary radar is what provides the &quot;blip&quot; on radar and tracks the airplane.  The datablock ATC has on the airplane comes from the secondary, so what ATC will see is a blip with no information.  Turning off the transponder is as simple as setting it to OFF or pulling a circuit breaker and yes, it can be selected OFF in flight, it is just a switch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with radar is that it only works so far from a radar transmitter and the further away you are the higher you must be to be seen by the radar.  Over the ocean away from land, you are going to be on the fringe of radar or out of radar contact completely and thus unable to be tracked directly by ATC (at this point, non-radar procedures such as position reporting and ETAs can be used to track positions).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight in question was apparently visible by a military radar before it disappeared from the scopes (it allegedly observed what appeared to be a turn back toward its origin).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="247" LastEditDate="2014-06-22T10:03:16.100" LastActivityDate="2014-06-22T10:03:16.100" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="2162" PostTypeId="2" ParentId="2160" CreationDate="2014-03-11T02:23:58.087" Score="18" Body="&lt;p&gt;With the proper knowledge of the aircraft systems almost anything can be turned off.  That's what we do at the end of almost every flight day.  Most of the communications systems can actually be turned off fairly easily, but the average person would not know how to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airplanes like the 777, there are multiple ways that they communicate but all of them can be turned off (transponders, ACARS reports, CPDLC, ADS-B, radios, satellite phones, etc.).  Some are automatic and some are manual,  and not all aircraft have all of them.  Most of them have a switch or can be controlled through the Flight Management System, but the ones that don't will have a circuit breaker designed to protect the system which may be pulled in order to deactivate the system. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="4" LastEditDate="2014-03-11T15:05:29.673" LastActivityDate="2014-03-11T15:05:29.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2163" PostTypeId="1" AcceptedAnswerId="2165" CreationDate="2014-03-11T04:44:43.367" Score="23" ViewCount="15222" Body="&lt;p&gt;If a commercial jet is in trouble, how does a pilot send a signal indicating distress? Does it take long?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, behind reception desks in many institutions and executive offices, there's a hidden red button that, when pressed, calls security or the police. (I know this since I sit at such a desk.) Do commercial airliners have a similar switch, or do they need to radio in for help? What happens when such a transmission is received?&lt;/p&gt;&#xA;" OwnerUserId="1354" LastEditorUserId="1354" LastEditDate="2014-03-12T18:05:31.170" LastActivityDate="2019-06-03T22:20:07.303" Title="How do commercial pilots send distress signals?" Tags="&lt;safety&gt;&lt;emergency&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2164" PostTypeId="2" ParentId="2163" CreationDate="2014-03-11T05:46:35.710" Score="19" Body="&lt;p&gt;It depends on the type of distress, but generally the easiest way to communicate a problem is to use the radio and describe the situation. However, there are some special transponder codes which will get the attention of any controller which has you on their radar screen.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;7500 indicates a hijacking&lt;/li&gt;&#xA;&lt;li&gt;7600 indicates a communications radio failure&lt;/li&gt;&#xA;&lt;li&gt;7700 indicates an emergency&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What happens after switching to one of these beacon codes depends on the scenario. In any of the cases, ATC will attempt to make contact with the aircraft. In most cases, they will also try to vector other traffic away from the aircraft for everyone's safety (especially true in the case of a hijacking).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume your question is primarily asking about a hijacking scenario. A recent, and very odd, example of 7500 being used is &lt;a href=&quot;http://www.airlinereporter.com/2014/02/breaking-ethiopian-airlines-flight-702-squawks-hijacking-reasons-unknown/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ethiopian Airlines’ Flight 702&lt;/a&gt; where the co-pilot actually hijacked the plane and squawked 7500. Unfortunately, pilots don't always have the time to reset the transponder if they are engaged in a physical fight in the cockpit. Also, the first step of the hijackers may be to turn off the transponder (this is what happened on 9/11), but if a controller is able to see the 7500 squawk, even briefly, it may help the controller understand what is happening if communications are lost, and to alert the military, if necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the other two &quot;distress&quot; signals:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For 7600 (lost communications) they will probably ask &quot;if you're receiving this, ident&quot; or &quot;if able, reset transponder code XXXX.&quot; If you comply with their request, it indicates that you can receive messages, but cannot transmit. A tracon or center controller might ask you to ident to acknowledge further instructions (when you ident, your datablock flashes on their screen), or just watch your actions closely. If you're on with a tower controller in visual conditions, rocking your wings or flashing your landing light can be used to acknowledge instructions. At towered airports, light-gun signals are used to give landing clearances when a pilot cannot receive radio communication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For 7700 (emergency) they will try to inquire as to the state of the emergency and offer any assistance possible, such as providing you suggested headings or information about nearby airports.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="3386" LastEditDate="2017-07-15T20:41:56.913" LastActivityDate="2017-07-15T20:41:56.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2165" PostTypeId="2" ParentId="2163" CreationDate="2014-03-11T06:00:23.230" Score="30" Body="&lt;p&gt;There are three common ways to send a distress signal (roughly in order of preference):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Over the radio, to whoever you are currently talking to.&lt;/strong&gt;&lt;br&gt;&#xA;Key the microphone and announce to the world &lt;code&gt;Mayday, Mayday, Mayday&lt;/code&gt;, the flight's callsign, and a description of the emergency. This is generally the way an emergency is declared, particularly for commercial (airline) service, as they're generally always in contact with an ATC facility&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Over the radio, to anyone monitoring the &quot;emergency&quot; frequency.&lt;/strong&gt;&lt;br&gt;&#xA;The VHF frequency 121.5MHz is reserved for aircraft emergency communication. It is monitored at most air traffic control facilities, as well as by many airliners and other pilots with multiple radios in their aircraft. If you're not able to make contact with the facility you're currently talking to in (1) above (or if you're not currently talking to an ATC facility).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Using the aircraft's transponder.&lt;/strong&gt;&lt;br&gt;&#xA;Three transponder codes are reserved for unusual/emergency situations:&lt;br&gt;&#xA;&lt;code&gt;7700&lt;/code&gt; for general emergencies&lt;br&gt;&#xA;&lt;code&gt;7600&lt;/code&gt; for loss of communication (radio failure)&lt;br&gt;&#xA;&lt;code&gt;7500&lt;/code&gt; for hijacking or other unlawful interference&lt;br&gt;&#xA;All of these transponder codes alter the way the aircraft's radar target is displayed, to alert the controller to the possible problem (exactly &lt;em&gt;how&lt;/em&gt; the display is modified depends on the radar equipment the controller has, and can range from additional text in the data block, like &lt;code&gt;RDOF&lt;/code&gt; (RaDiO Failure) for code &lt;code&gt;7600&lt;/code&gt; to changing the color of the displayed block on newer systems.&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/2164/64&quot;&gt;Bret detailed some of the procedures around these codes in his answer&lt;/a&gt;, and more information is available &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0502.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;from the FAA&lt;/a&gt;, though you'll have to dig through a few referenced documents to put it all together.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that sometimes the order of preference changes - For example if a pilot is being threatened by a hijacker they may quietly set their transponder code to 7500 &lt;em&gt;without&lt;/em&gt; saying anything on the radio to alert the hijacker.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-03-11T06:00:23.230" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2169" PostTypeId="2" ParentId="2160" CreationDate="2014-03-11T14:54:42.307" Score="7" Body="&lt;p&gt;With today's locked cockpit policy it is extremely unlikely that hijackers would be able to turn off the transponder without pilots being able to set it to 7500, the code for unlawful interference, for at least a short while. Because while the transponder can be turned off, the hijackers would have to get into the cockpit first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpit door &lt;em&gt;can't&lt;/em&gt; be opened from cabin side. Even if the stronger code is entered that will open the door (for cases when one pilot is incapacitated while the other is in the lavatory) the pilots still have some time to cancel the unlock request. Therefore the hijackers would have to threaten with something to get the pilots unlock, but that would give the pilots time to provide some indication of the hijack to the ATC.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="97" LastEditDate="2014-03-11T23:32:14.777" LastActivityDate="2014-03-11T23:32:14.777" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2170" PostTypeId="1" CreationDate="2014-03-11T16:09:27.737" Score="40" ViewCount="55381" Body="&lt;p&gt;In Top Gun, Maverick's F-14 enters a flat spin after flying through another F-14's jetwash, forcing him to eject and causing the death of Goose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this scenario possible or was it only created for theatrical purposes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, how does it happen, and how can it be avoided, especially for other types of aircraft such as the B-2?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="64" LastEditDate="2014-03-13T05:51:39.253" LastActivityDate="2019-11-21T07:11:02.103" Title="Is it possible to recover from a flat spin?" Tags="&lt;military&gt;&lt;spins&gt;" AnswerCount="8" CommentCount="10" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2171" PostTypeId="1" AcceptedAnswerId="2172" CreationDate="2014-03-11T16:37:25.673" Score="11" ViewCount="930" Body="&lt;p&gt;Recently there was a mishap at South Lakeland Airport in Mulberry, Florida where a &lt;a href=&quot;http://www.flyingmag.com/technique/accidents/cessna-170b-pilot-and-skydiver-survive-collision&quot; rel=&quot;noreferrer&quot;&gt;Cessna 170 collided with a skydiver&lt;/a&gt;. Luckily all involved suffered only minor injuries. As far as I know, skydiving in Germany must be NOTAMed, is this not the case in the US?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident was caught on a &lt;a href=&quot;http://www.flyingmag.com/photo-gallery/photos/skydiver-and-cessna-170b-mid-air-collision-photos?pnid=47561&quot; rel=&quot;noreferrer&quot;&gt;series of stills&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://pbs.twimg.com/media/Bic2OgrCQAA-Wqj.jpg&quot; alt=&quot;Skydiver vs. airplane&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="690" LastEditDate="2015-11-17T15:11:22.057" LastActivityDate="2015-11-17T15:11:22.057" Title="Is skydiving not NOTAMed in the US?" Tags="&lt;usa&gt;&lt;skydiving&gt;&lt;notam&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2172" PostTypeId="2" ParentId="2171" CreationDate="2014-03-11T17:03:33.063" Score="12" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr105_main_02.tpl&quot;&gt;14 CFR 105&lt;/a&gt; covers parachute operations in the USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is not a requirement for a NOTAM, but since this happened at an uncontrolled airport the nearest ATC facility must be notified at least 1 hour in advance but not more than 24 hours in advance and, they must have approval from airport management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then for the actual jump, ATC must be notified at least 5 minutes prior to jump via radio from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=9378f3a8d784e1828fcf0b8edba51ffd&amp;amp;node=14:2.0.1.3.17.1.9.6&amp;amp;rgn=div8&quot;&gt;&lt;strong&gt;§105.23   Parachute operations over or onto airports.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may conduct a parachute operation, and no pilot in command&#xA;  of an aircraft may allow a parachute operation to be conducted from&#xA;  that aircraft, over or onto any airport unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) For airports with an operating control tower:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Prior approval has been obtained from the management of the&#xA;  airport to conduct parachute operations over or on that airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Approval has been obtained from the control tower to conduct&#xA;  parachute operations over or onto that airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Two-way radio communications are maintained between the pilot of&#xA;  the aircraft involved in the parachute operation and the control tower&#xA;  of the airport over or onto which the parachute operation is being&#xA;  conducted.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For airports without an operating control tower, prior approval&#xA;  has been obtained from the management of the airport to conduct&#xA;  parachute operations over or on that airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) A parachutist may drift over that airport with a fully deployed&#xA;  and properly functioning parachute if the parachutist is at least&#xA;  2,000 feet above that airport's traffic pattern, and avoids creating a&#xA;  hazard to air traffic or to persons and property on the ground.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=9378f3a8d784e1828fcf0b8edba51ffd&amp;amp;node=14:2.0.1.3.17.1.9.7&amp;amp;rgn=div8&quot;&gt;&lt;strong&gt;§105.25   Parachute operations in designated airspace.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may conduct a parachute operation, and no pilot in&#xA;  command of an aircraft may allow a parachute operation to be conducted&#xA;  from that aircraft—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Over or within a restricted area or prohibited area unless the&#xA;  controlling agency of the area concerned has authorized that parachute&#xA;  operation;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Within or into a Class A, B, C, D airspace area without, or in&#xA;  violation of the requirements of, an air traffic control authorization&#xA;  issued under this section;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Except as provided in paragraph (c) and (d) of this section,&#xA;  within or into Class E or G airspace area unless the air traffic&#xA;  control facility having jurisdiction over the airspace at the first&#xA;  intended exit altitude is notified of the parachute operation no&#xA;  earlier than 24 hours before or no later than 1 hour before the&#xA;  parachute operation begins.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Each request for a parachute operation authorization or&#xA;  notification required under this section must be submitted to the air&#xA;  traffic control facility having jurisdiction over the airspace at the&#xA;  first intended exit altitude and must include the information&#xA;  prescribed by §105.15(a) of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) For the purposes of paragraph (a)(3) of this section, air traffic&#xA;  control facilities may accept a written notification from an&#xA;  organization that conducts parachute operations and lists the&#xA;  scheduled series of parachute operations to be conducted over a stated&#xA;  period of time not longer than 12 calendar months. The notification&#xA;  must contain the information prescribed by §105.15(a) of this part,&#xA;  identify the responsible persons associated with that parachute&#xA;  operation, and be submitted at least 15 days, but not more than 30&#xA;  days, before the parachute operation begins. The FAA may revoke the&#xA;  acceptance of the notification for any failure of the organization&#xA;  conducting the parachute operations to comply with its requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Paragraph (a)(3) of this section does not apply to a parachute&#xA;  operation conducted by a member of an Armed Force within a restricted&#xA;  area that extends upward from the surface when that area is under the&#xA;  control of an Armed Force.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even more information is available in &lt;a href=&quot;http://www.uspa.org/Portals/0/Downloads/AC105-2E.pdf&quot;&gt;AC 105-2E&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-11T17:03:33.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2173" PostTypeId="1" AcceptedAnswerId="2176" CreationDate="2014-03-11T18:34:29.480" Score="10" ViewCount="2238" Body="&lt;p&gt;I'm very interested to learn if there are (m)any (major) (commercial) airports that have runways further away from the terminal(s) than Schiphol's Polderbaan. Which airport is &amp;quot;in the lead&amp;quot; in this respect?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The northern end of the Polderbaan, the last runway to be constructed, is 7 km (4.3 mi) north of the control tower, causing taxi times of up to 20 minutes to the terminal.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;Newest runway, opened 2003.&#xA;Located to reduce the noise impact on the surrounding population; aircraft have a lengthy 15-minute taxi to and from the Terminal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Amsterdam_Airport_Schiphol#Runways&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Wikipedia&lt;/em&gt;&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1379" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-03-10T19:48:57.167" Title="Is AMS (Schiphol) Polderbaan the runway furthest away?" Tags="&lt;airport&gt;&lt;taxiing&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2174" PostTypeId="1" CreationDate="2014-03-11T18:55:38.917" Score="0" ViewCount="166" Body="&lt;p&gt;Can anyone explain how a Boeing 777-200 can vanish without a trace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can it simply disappear without any indication of an in-flight emergency from the flight crew?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does its disappearance and lack of any physical evidence suggest a catastrophic in-flight emergency which unfolded so rapidly that it caught the flight crew off guard and unable to send a distress signal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible for someone other than the flight crew to disable its transponder or alter its radar signature to render it undetectable?&lt;/p&gt;&#xA;" OwnerUserId="1380" LastEditorUserId="64" LastEditDate="2014-03-14T15:29:10.283" LastActivityDate="2014-03-14T15:29:10.283" Title="Boeing 777 MHA370" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;boeing&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-03-11T21:08:03.297" ContentLicense="CC BY-SA 3.0" />
  <row Id="2175" PostTypeId="1" AcceptedAnswerId="3449" CreationDate="2014-03-11T18:55:44.637" Score="11" ViewCount="6864" Body="&lt;p&gt;The Netherlands has a few &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurocopter_EC135&quot;&gt;Eurocopter EC135&lt;/a&gt;s for air medical services. (See &lt;a href=&quot;http://nl.wikipedia.org/wiki/Mobiel_Medisch_Team#Huidig_gebruik&quot;&gt;&lt;em&gt;Wikipedia&lt;/em&gt;&lt;/a&gt;.) How much clear landing space is required (either theoretically, practically or regulatory) for these?&lt;/p&gt;&#xA;" OwnerUserId="1379" LastEditorUserId="97" LastEditDate="2014-04-17T22:44:42.757" LastActivityDate="2019-02-21T10:32:58.577" Title="What is the minimal landing area required for an EC135 air medical services helicopter?" Tags="&lt;landing&gt;&lt;helicopter&gt;&lt;emergency-services&gt;&lt;netherlands&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2176" PostTypeId="2" ParentId="2173" CreationDate="2014-03-11T19:44:48.923" Score="9" Body="&lt;p&gt;One possible contender is Pyongyang airport. The far end of the new runway (01/19) is around 7 km away from the terminal (as the crow flies). With taxi distance, it is almost 8 km:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2wWB2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2wWB2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.jspacesystems.or.jp/ersdac/ASTERimage3/Image/Asia/INJ_Pyongyang.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the taxi times at Amsterdam can be very long, it is a bit misleading to blame it on the runway being 7 km away. Runway 18R is not used for takeoff. Unlike Pyongyang, there is no parallel taxiway on that 'end' of the runway, and Schiphol ATC would never want to wait for an aircraft to backtrack. Hence, it would be more sensible to use the distance from the first taxiway for landing aircraft on 18R, located 5.5 km from the tower.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2017-03-10T19:48:57.167" LastActivityDate="2017-03-10T19:48:57.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2177" PostTypeId="2" ParentId="2160" CreationDate="2014-03-11T19:50:41.533" Score="8" Body="&lt;p&gt;As a B-737 pilot, I can tell you that ALL electrical components are wired into the electrical system to a specific electrical BUS. It would not be hard to determine which BUS(S) run power to the associated component and therefore knowing which circuit breaker(s) to pull. The ACARS that transmits our FOQA information can be disconnected on the BBJ I fly. I assume it can be done in the B-777. &lt;/p&gt;&#xA;" OwnerUserId="1382" LastActivityDate="2014-03-11T19:50:41.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2178" PostTypeId="2" ParentId="2175" CreationDate="2014-03-11T19:51:14.463" Score="5" Body="&lt;p&gt;I don't think there's a hard and fast rule for this, but it depends on a number of factors:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind/ Weather conditions requiring safety margins.&lt;/li&gt;&#xA;&lt;li&gt;Effect of nearby objects/structures. If they are big I think they might cause unpredictable wind effects, again requiring compensation and space.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KDwWe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KDwWe.jpg&quot; alt=&quot;parkinglot&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.flugzeug-bild.de/bilder/ec-135-448.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;flugzeug-bild.de&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;That said, I'm no helicopter pilot, so somebody else might be able to give a more detailed answer. YouTube is a pretty decent place to find some tight landings though.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-02-21T10:32:58.577" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2180" PostTypeId="2" ParentId="2159" CreationDate="2014-03-11T19:57:08.637" Score="1" Body="&lt;p&gt;I got the answer.  'C' is commercial, 'G' general aviation, 'T' taxi, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/fss/AppendixA.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/air_traffic/publications/atpubs/fss/AppendixA.htm&lt;/a&gt;, under section &quot;Type of flight&quot;, it lists&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;S  if scheduled air service&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;N  if non­scheduled air transport operation&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;G  if general aviation&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;M  if military&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;X  if other than any of the defined categories above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But types C and T isn't there.&lt;/p&gt;&#xA;" OwnerUserId="1349" LastEditorUserId="1349" LastEditDate="2014-10-03T23:19:17.763" LastActivityDate="2014-10-03T23:19:17.763" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2182" PostTypeId="2" ParentId="2149" CreationDate="2014-03-12T04:13:31.763" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://www.digitalglobe.com/&quot; rel=&quot;nofollow&quot;&gt;Digital Globe&lt;/a&gt;, a satellite imaging company (who provide a lot of the data Google uses), has done this for the MH370 flight using a platform called &lt;a href=&quot;http://www.tomnod.com/nod/challenge/malaysiaairsar2014&quot; rel=&quot;nofollow&quot;&gt;Tomnod&lt;/a&gt;, which is currently directing all users straight to the search page. The images they're showing now were taken on 3/9, so apparently they are able to re-task their satellites fairly quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More info on how to use this is available at &lt;a href=&quot;http://www.zerosixright.com/how-to-use-tomnod-to-find-mh370/&quot; rel=&quot;nofollow&quot;&gt;How To Use Tomnod To Find MH370&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Something similar was done using Amazon Mechanical Turk during the search for Jim Gray.&lt;/p&gt;&#xA;" OwnerUserId="1388" LastEditorUserId="97" LastEditDate="2014-03-14T02:45:24.890" LastActivityDate="2014-03-14T02:45:24.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2183" PostTypeId="1" AcceptedAnswerId="2184" CreationDate="2014-03-12T05:53:02.037" Score="9" ViewCount="6313" Body="&lt;p&gt;In case of a total power failure in all the aircraft systems like engine failure and APU failure, would it be possible to use mechanical means (manually) to open the landing gear bay door and deploy the landing gear through mechanical means?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know it’s possible to glide the flight if the engines failed. But, wondering how they land.&lt;/p&gt;&#xA;" OwnerUserId="1337" LastEditorUserId="62" LastEditDate="2020-02-09T23:40:16.250" LastActivityDate="2020-02-09T23:40:16.250" Title="Will the landing gear work mechanically in case of total power loss?" Tags="&lt;landing&gt;&lt;landing-gear&gt;&lt;engine-failure&gt;&lt;electrical-system&gt;&lt;apu-failure&gt;" AnswerCount="7" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2184" PostTypeId="2" ParentId="2183" CreationDate="2014-03-12T07:15:34.293" Score="12" Body="&lt;p&gt;Not a real example, but this comes from the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch13.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA&lt;/a&gt;, including some nice drawings around page 13-20:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The emergency extension system lowers the landing gear if  the main&#xA;power system fails. There are numerous ways in  which this is done&#xA;depending on the size and complexity of  the aircraft. Some aircraft&#xA;have an emergency release handle  in the flight deck that is connected&#xA;through a mechanical  linkage to the gear uplocks. When the handle is&#xA;operated, it  releases the uplocks and allows the gear to free-fall to&#xA;the  extended position under the force created by gravity acting  upon&#xA;the gear. Other aircraft use a non-mechanical back-up,  such as&#xA;pneumatic power, to unlatch the gear.&lt;/p&gt;&#xA;&lt;p&gt;The popular small aircraft retraction system ..... uses a free-fall valve for emergency  gear extension. Activated from the flight deck,&#xA;when the  free-fall valve is opened, hydraulic fluid is allowed to&#xA;flow  from the gear-up side of the actuators to the gear-down side  of&#xA;the actuators, independent of the power pack. Pressure  holding the&#xA;gear up is relieved, and the gear extends due to  its weight. Air&#xA;moving past the gear aids in the extension  and helps push the gear&#xA;into the down-and-locked position.&lt;/p&gt;&#xA;&lt;p&gt;Large and high performance aircraft&#xA;are equipped with  redundant hydraulic systems. This makes emergency&#xA;extension less common since a different source of hydraulic  power can&#xA;be selected if the gear does not function normally.&lt;/p&gt;&#xA;&lt;p&gt;In some small aircraft, the design configuration makes  emergency&#xA;extension of the gear by gravity and air loads  alone impossible or&#xA;impractical. Force of some kind must  therefore be applied. Manual&#xA;extension systems, wherein  the pilot mechanically cranks the gear&#xA;into position, are  common. Consult the aircraft maintenance manual&#xA;for all  emergency landing gear extension system descriptions of&#xA;operation, performance standards, and emergency extension  tests as&#xA;required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-12T07:15:34.293" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2185" PostTypeId="1" AcceptedAnswerId="2213" CreationDate="2014-03-12T07:34:14.090" Score="37" ViewCount="75815" Body="&lt;p&gt;On aircraft which fly above 30,000 feet, the temperature can often can get to temperatures below Jet-A's freezing point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example: at 36,000 feet the standard outside air temperature is -56.5°C (-69.7°F) and is well below Jet-A's freezing point of -40°C/F. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What measures are put in place on aircraft to mitigate the risk of the fuel in the tanks freezing and preventing the engines from operating?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="69" LastEditDate="2015-09-24T23:33:56.333" LastActivityDate="2018-12-30T00:39:46.690" Title="How do aircraft keep fuel from freezing while in flight?" Tags="&lt;safety&gt;&lt;fuel&gt;&lt;jet-engine&gt;&lt;fixed-wing&gt;&lt;temperature&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2186" PostTypeId="1" AcceptedAnswerId="2223" CreationDate="2014-03-12T08:37:16.460" Score="67" ViewCount="66830" Body="&lt;p&gt;I understand that commercial flights are equipped with life vests. I also understand that most military jets are equipped with ejection seats. It may be costly and technically challenging to equip passenger planes with ejection seats. Having seen air-borne personnel lining up and parachuting out of a C130, what is preventing flights from equipping each passenger with a life-saving parachute? Is it very technically challenging for an untrained person to deploy a parachute, or are there other reasons?&lt;/p&gt;&#xA;" OwnerUserId="1390" LastEditorUserId="3386" LastEditDate="2017-07-11T23:05:07.777" LastActivityDate="2017-07-11T23:05:07.777" Title="Why are commercial flights not equipped with parachutes for the passengers?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;emergency&gt;&lt;parachute&gt;" AnswerCount="14" CommentCount="14" FavoriteCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="2187" PostTypeId="2" ParentId="2185" CreationDate="2014-03-12T08:57:39.367" Score="7" Body="&lt;p&gt;Most Jet engine fuel systems have means to heat the fuel to prevent it from freezing. Typical heat exchange methods followed are by employing hot air or hot oil taken from the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference: FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/amt_airframe_hb_vol_1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Maintenance Technician Handbook, Chapter 14: Aircraft Fuel System&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1391" LastEditorUserId="36291" LastEditDate="2018-12-30T00:39:46.690" LastActivityDate="2018-12-30T00:39:46.690" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="2188" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T09:06:45.060" Score="40" Body="&lt;p&gt;Parachutes are heavy, expensive, difficult to use and will be useless in pretty much any air disaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to parachute from a commercial aircraft it would need to be&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;in a stable attitude, &lt;/li&gt;&#xA;&lt;li&gt;at low speed &lt;/li&gt;&#xA;&lt;li&gt;and below about 12 000 ft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Short of an aircraft losing power to all engines like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;Gimli Glider&lt;/a&gt;, in which case ditching in the ocean or finding an open space to land is preferable to parachuting your passengers out, I can't think of any other catastrophic failure that would give you the opportunity to let passengers leave by parachute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's aside from the difficulty of trying to get passengers, most of whom are panicking, to properly don a parachute and tighten the necessary straps. With a lifejacket a person can still hold onto it in the water if they didn't do the straps right, but the same is not true for a parachute.&lt;/p&gt;&#xA;" OwnerUserId="1263" LastEditorUserId="247" LastEditDate="2014-03-15T10:07:02.783" LastActivityDate="2014-03-15T10:07:02.783" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="2189" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T09:36:09.030" Score="24" Body="&lt;p&gt;Using a parachute is not a easy job. It require large amount of training, even well trained army para units face more casualties during para jumping. The key odds for using parachute in a commercial airline are&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Untrained personal using a parachute is much more risky and it may not serve the purpose of saving the life. We may not expect all the passengers of a commercial airliner to have attended a para jumping trainings. &lt;/li&gt;&#xA;&lt;li&gt;Jumping from an airliner at higher altitude requires supplemental oxygen and requires special training.&lt;/li&gt;&#xA;&lt;li&gt;Cost of a parachute is much higher. So, this would increase the cost of ticket and the benefit out of it is significantly limited. This would not be economically possible.&lt;/li&gt;&#xA;&lt;li&gt;The parachutes need to be maintained periodically. Maintaining few hundred parachutes per aircraft would increase the ideal time of the aircraft which leads to cost overruns. &lt;/li&gt;&#xA;&lt;li&gt;It would be literally impossible for children’s, peoples with disabilities to use the parachutes.&lt;/li&gt;&#xA;&lt;li&gt;Opening a pressurized cabin at a higher altitude would result in a decrease in altitude due to heavy inflow of air and would make the situation even worse. &lt;/li&gt;&#xA;&lt;li&gt;Parachute jumping needs a stable platform and a steady aircraft. But, in a commercial airliner which is in dangerous conditions it is practically impossible. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1337" LastActivityDate="2014-03-12T09:36:09.030" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="2191" PostTypeId="5" CreationDate="2014-03-12T09:51:42.740" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-12T09:51:42.740" LastActivityDate="2014-03-12T09:51:42.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2192" PostTypeId="4" CreationDate="2014-03-12T09:51:42.740" Score="0" Body="Holding is the practice of flying circles or circuits in order wait for an ATC clearance to proceed further. " OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-03-12T13:02:51.553" LastActivityDate="2014-03-12T13:02:51.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2193" PostTypeId="2" ParentId="2021" CreationDate="2014-03-12T10:06:49.257" Score="8" Body="&lt;p&gt;Apart from Manfred's answer, there are other factors in play:&lt;br/&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airlines make quite a nice income from the payphones in aircraft&lt;/li&gt;&#xA;&lt;li&gt;Cellphone towers typically have pretty bad (if any) reception straight up, they're designed for ground level use after all which dictates the design of their antennae (an omnidirectional one is a lot less energy efficient)&lt;/li&gt;&#xA;&lt;li&gt;People in border regions already complain about being hit by roaming charges when they set their phones to automatically switch networks. In an aircraft that'd be multiplied as those foreign towers might be in range from further inside a nation's borders (but see previous point as to why maybe not).&lt;/li&gt;&#xA;&lt;li&gt;keeping a quiet cabin. As hinted, 150+ passengers all yacking away on their cellphones (and most people tend to shout into the darn things) make one hell of a racket. Bad marketing for the airline. Everyone wants every other passenger to be quiet and behave but want for themselves the right to do whatever they want, other passengers be darned.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-12T10:06:49.257" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2194" PostTypeId="1" AcceptedAnswerId="2195" CreationDate="2014-03-12T11:20:23.673" Score="10" ViewCount="1890" Body="&lt;p&gt;In February 2014 a co-pilot hijacked &lt;a href=&quot;http://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_702_hijacking&quot; rel=&quot;noreferrer&quot;&gt;Ethopian Airlines flight 702&lt;/a&gt; and took it to Switzerland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in March there is some speculation that &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;noreferrer&quot;&gt;Malaysia Airlines flight 370&lt;/a&gt; may have been hijacked and destroyed by the pilots - maybe they took a nose dive into the Andaman Sea?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is this: is there an automatic or say &lt;strong&gt;anti-pilot warning system&lt;/strong&gt; on commercial airliners?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, a system that is non-maskable (can't be disabled by the pilot) and which will automatically warn ATC about unexpected conditions (like a sudden decrease in altitude)?&lt;/p&gt;&#xA;" OwnerUserId="1395" LastEditorUserId="64" LastEditDate="2014-03-13T02:15:48.247" LastActivityDate="2015-04-03T12:00:24.507" Title="Do airliners have an &quot;anti-pilot&quot; warning system?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;radar&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2195" PostTypeId="2" ParentId="2194" CreationDate="2014-03-12T11:42:29.467" Score="15" Body="&lt;p&gt;The system you're asking about is called radar: ATC should monitor it to see what the plane is doing and ask what is going on when something unexpected happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to &quot;automate&quot; these kinds of alerts. For example, a sudden dive can also be cause by an uncontrolled control-surface hard-over (like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_rudder_issues&quot; rel=&quot;noreferrer&quot;&gt;boeing 737 rudder problems&lt;/a&gt; that brought down 2 planes), or a loss of cabin pressurization (which requires a rapid descent to an altitude where your passengers can breathe).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other option is having a second person in the cockpit who can wrest control away from the disobedient pilot (or let people in the cockpit to help).&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-04-03T12:00:24.507" LastActivityDate="2015-04-03T12:00:24.507" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2196" PostTypeId="2" ParentId="2021" CreationDate="2014-03-12T11:50:03.607" Score="0" Body="&lt;p&gt;if we use a cellphone in an aeroplane it might disturb connection between the controlroom and plane and also between radar. which will be dangerous that it makes unable to connect the control room for an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i think this is the reason that cellphones are not allowed to use in planes&lt;/p&gt;&#xA;" OwnerUserId="1336" LastActivityDate="2014-03-12T11:50:03.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2197" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T14:30:58.173" Score="30" Body="&lt;p&gt;Almost all fatal accidents happen during take-off or landing, where parachutes would not be of any help. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the accident happens at a higher altitude, and the aircraft is still more ore less flyable, it is much less risky to attempt an emergency landing and save most or all of the passengers, than risk parachuting them (the other answers have plenty of reasons why it's risky). If the aircraft can't maintain speed and altitude, you don't have the time to parachute even cooperating passengers, much less panicked ones.&lt;/p&gt;&#xA;" OwnerUserId="1307" LastActivityDate="2014-03-12T14:30:58.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2198" PostTypeId="1" CreationDate="2014-03-12T15:08:22.843" Score="43" ViewCount="31729" Body="&lt;p&gt;It seems strange that trucks and taxis can be set up to transmit GPS data in real time but aircraft cannot.  Wouldn't this be a useful function and feasible to implement?&lt;/p&gt;&#xA;" OwnerUserId="788" LastEditorUserId="15311" LastEditDate="2019-09-13T12:40:59.033" LastActivityDate="2019-09-13T12:40:59.033" Title="Why don't all commercial aircraft transmit GPS data in real time?" Tags="&lt;commercial-aviation&gt;&lt;avionics&gt;&lt;gnss&gt;&lt;ads-b&gt;" AnswerCount="12" CommentCount="10" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2199" PostTypeId="2" ParentId="2198" CreationDate="2014-03-12T15:30:55.670" Score="4" Body="&lt;p&gt;there is already something like that, the primary and secondary radars allows for positional data to be received by the controller, so adding this is superfluous from FAA's standpoint. To do this voluntarily is expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To roll out a transmission of gps position data you need someone to be listening to it. Cars use the existing mobile network. Planes would likely use the transponder frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also still need to be compatible to existing transponders while the global rollout happens.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-03-12T15:30:55.670" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2200" PostTypeId="2" ParentId="2198" CreationDate="2014-03-12T15:44:44.120" Score="2" Body="&lt;p&gt;No, it wouldn't be useful. And no, it would be exceedingly hard to implement, not to mention exceedingly expensive.&lt;br/&gt;&#xA;Cars and trucks are rarely out of range of cellphone towers, which is the system they use to transmit that data to their company headquarters. Mind that that's only used for some trucking and taxi companies, and a few car rental and lease companies, not generally (though there are some governments that are pushing for it, which has very strong privacy considerations as essentially your location would be known to the government within a short radius at any time, Big Brother is watching you...).&lt;br/&gt;&#xA;It's used mainly for fleet management purposes, like a rental agency can use it to pinpoint you to being where that speeding ticket was written so they can tell police who to send the fine to (and the points on your license).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;The equipment for cars and trucks is also small, weighing in at maybe a pound (including mounting brackets, cables, etc.) and drawing little power.&lt;br/&gt;&#xA;For aircraft, it would need to be larger as instead of a small cellphone transceiver it would need a satellite radio link and antenna. It would also as a result draw a lot more power, which means higher fuel use on top of the extra fuel use from the higher weight of the aircraft (ignoring the possible extra drag from the antenna which makes it even worse).&lt;br/&gt;&#xA;And it's not real time, obviously, the cost would get to be far too high. Most cars and trucks would send an update only once every few minutes at most (selectable). &lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And aircraft already have something like it anyway, with systems that can send location and status data to the airline. But it's triggered manually, usually, and not in universal use.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Such a system would have virtually no purpose, and a high cost of operating it. You'd need not just a small box in every aircraft, you'd need a network of communications satellites, ground stations around the world with 24/7 staff on hand, etc. etc.&lt;br/&gt;&#xA;And I seriously doubt you're going to want to add a few hundred dollars to the price of every ticket just in the off chance that when your flight goes down someone can find the wreck a bit sooner.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-12T15:44:44.120" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2201" PostTypeId="2" ParentId="2198" CreationDate="2014-03-12T15:47:51.727" Score="5" Body="&lt;p&gt;The main problem with this is that it is somewhat easy to know where the device is, it's a lot harder for the device to tell someone else where it is.  Satellites are really the only option for this sort of thing, and a lot of the polar routes have pretty poor satellite coverage anyways.  Also, satellite bandwidth is quite expensive.&lt;/p&gt;&#xA;" OwnerUserId="162" LastActivityDate="2014-03-12T15:47:51.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2202" PostTypeId="2" ParentId="2198" CreationDate="2014-03-12T16:15:04.983" Score="65" Body="&lt;p&gt;Most commercial aircraft transmit their GPS-based position twice per second. This is part of their &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Automatic Dependent Surveillance – Broadcast&lt;/em&gt; (ADS–B)&lt;/a&gt; broadcasts. The problem with providing world-wide receiver coverage for this system is that the frequency it uses only travels line via line of sight, so it won't travel past the horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Providing coverage over large bodies of water would require a network of buoys, which would be quite expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility is to put ADS-B receivers on satellites. This concept has been developed by (&lt;a href=&quot;http://www.aireon.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aireon&lt;/a&gt;) on the Iridium Next satellite constellation. The system (66 satellites + 9 spares) became operational in 2019 and provides global coverage.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="23223" LastEditDate="2019-09-13T08:51:27.407" LastActivityDate="2019-09-13T08:51:27.407" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="2203" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T16:43:11.617" Score="21" Body="&lt;p&gt;The profit in aviation in 2013 was about \$11.7 billion, on \$708 billion revenues. So the profit margin in global aviation last year was about 1.6%. How do you expect that to work when you remove about 10% of the fare-paying passengers by replacing them with 8-10kg parachutes? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is about \$70.8 billion you lose there, every year. Assuming it would save 240 lives every five years (I am being optimistic here), that's about \$1.5 billion per life saved. If you have that amount of money to invest, I can think of more efficient ways to make aviation safer than by adding parachutes which &lt;em&gt;might&lt;/em&gt; help in a crash once every five to ten years.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="938" LastEditDate="2014-10-29T16:56:27.833" LastActivityDate="2014-10-29T16:56:27.833" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2204" PostTypeId="2" ParentId="2198" CreationDate="2014-03-12T16:48:18.610" Score="3" Body="&lt;p&gt;From a documentary on the 2009 Air France crash: I remember an aviation expert answering the same question. He said that it is expensive (About extra $300 million for a typical national carrier per year) and Airliners are reluctant to take on any additional expenses even if such an undertaking improves safety (The Air France jet crashed because the Pitot tubes froze thus disengaging the auto pilot. The Airline was aware that the Pitot tubes needed to be replaced way before the accident but did nothing because it was expensive).&lt;/p&gt;&#xA;" OwnerUserId="1403" LastEditorUserId="1403" LastEditDate="2014-03-12T17:59:01.090" LastActivityDate="2014-03-12T17:59:01.090" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2207" PostTypeId="2" ParentId="1070" CreationDate="2014-03-12T18:40:33.283" Score="-4" Body="&lt;p&gt;Thanks to all for answers. The $\frac{1.97}{96}$ was not correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is how you should do it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$3.2=\frac{670ft\times60}{3.2}=12,562ft=2.066NM$$&lt;/p&gt;&#xA;" OwnerUserId="1410" LastEditorUserId="97" LastEditDate="2014-04-18T03:31:17.090" LastActivityDate="2014-04-18T03:31:17.090" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2209" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T19:45:36.143" Score="12" Body="&lt;p&gt;There are several good answers above, but another important thing to consider is that it's impossible to jump out of a commercial airliner (except the 727, which is rarely still found in passenger aviation) while in flight, unless a hole has opened in the fuselage or it has otherwise become depressurized. The doors have to be pulled in to open, which is, for all practical purposes, impossible while the airframe is pressurized. From a safety perspective, the additional risk of allowing the doors to open in flight far outweighs the potential benefit of letting people bail out in the narrow range of circumstances that that would even be possible. This is because it would require the doors to open outward, which opens up the possibility of them blowing out in flight. Back when airplanes were designed that way, several people died from explosive decompression due to a door blowing out. This was a problem both on the DC-10 and on early 747s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A further issue to consider is the locations of the exits. The reason that it was possible to bail from a 727 is that it had an exit in the tail cone. No other passenger aircraft that I'm aware of has that. Many military cargo planes (like the C-130 you mentioned) do use ramps in the tail, though, and that's where people jump out from in those aircraft. If you try to jump from a side door in a jetliner (which are the only doors that exist in most modern jetliners,) you'll likely be promptly cut in half by the horizontal stabilizers moving through you at 550 mph immediately after stepping out the door. Of course, this would also damage the horizontal stabilizer, which would then quite likely result in the death of everyone still on the plane, due to loss of pitch authority. Of course, if you jump out of a door in front of the wings, you might be killed by a wing or an engine rather than a horizontal stabilizer, but the results are still equally undesirable. Jumping out of side doors is possible (and normal) for the much slower aircraft used for skydiving, but not for a passenger jet moving 550 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have time at the moment to run all of the numbers, but one thing did come to mind that helps in the comparison: terminal velocity. Terminal velocity is the point at which the upward drag on a falling object is equal to the downward gravitational force and, thus, downward acceleration due to gravity stops. Where this provides some insight on this question is in the comparison of forces. Terminal velocity for a human is about 120 mph at low altitude. This means that the wind speed required to equal the gravitational force is approximately 120 mph at low altitude (of course, this can vary depending on the shape and mass of the person in question and their position relative to the airflow.) Since drag is proportional to the square of velocity and linearly proportional to air density, this means that a 550 mph wind at an altitude where air density was roughly $\frac13$ of at the surface would exert a force with a magnitude of about $(\frac{550}{120})^2(\frac13)\approx7$ times the magnitude of the gravitational force. So, at least initially, you'd be accelerated backwards about 7 times as quickly as you'd be accelerated downwards by gravity in these conditions. Aside from the fact that being accelerated backwards at around 7 Gs is going to hurt, there is a very real possibility of hitting any part of the aircraft that happens to be behind you. Also, as mentioned in a comment below, it would actually be entirely possible to be accelerated &lt;em&gt;upwards&lt;/em&gt; (at least briefly) with that much drag, depending on the average angle at which your body is deflecting the wind stream. Another consideration is that the windstream itself will be faster than the true airspeed of the aircraft itself around certain parts of the aircraft, including around the fuselage and above and behind the wings. Furthermore, the airstream is not always exactly parallel with the aircraft. It can have an upward component relative to the aircraft around certain parts of the airframe while it almost always has a downward component relative to the aircraft behind the trailing edge of the wings. Also, if the plane itself is descending, there will be an upward component of the airstream relative to the aircraft at almost all points, except maybe right behind the wings. So, long story short, a lot of factors play into this, but things aren't looking up for the prospective jumper.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="97" LastEditDate="2014-04-17T02:48:55.810" LastActivityDate="2014-04-17T02:48:55.810" CommentCount="24" ContentLicense="CC BY-SA 3.0" />
  <row Id="2210" PostTypeId="2" ParentId="2186" CreationDate="2014-03-12T21:10:45.493" Score="36" Body="&lt;p&gt;The main reason that parachutes are not used is that there are very, &lt;strong&gt;very&lt;/strong&gt; few aircraft accidents that occur with enough &lt;strong&gt;time&lt;/strong&gt; to actually use one.  In fact, I'm not sure that there have been any.  Below are a couple examples that you may originally think that parachutes could have been useful on because they initiated from a high altitude.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Air France 447:&lt;/h1&gt;&#xA;&lt;p&gt;The short version is that they stalled the airplane at cruising altitude and held it in the stall until it crashed into the ocean.&lt;/p&gt;&#xA;&lt;p&gt;Let's consider that the amount of time from the peak altitude of the aircraft until impact with water was only 3 minutes and 21 seconds.  Let's be &lt;strong&gt;very&lt;/strong&gt; generous and say that everybody on board immediately knew that the aircraft was going to crash and there was nothing that the pilots could do.&lt;/p&gt;&#xA;&lt;p&gt;This gives the panicking passengers just over three minutes to get their parachutes out of storage, properly secure themselves into the harness (which, trust me, isn't as easy as it sounds even if you know what you are doing and are in the proper frame of mind), all while in the confined space of an aircraft seat with everyone else around them doing the same thing.  After that, we somehow need to open the doors and get people to orderly line up and exit the airplane without freaking out and getting scared.&lt;/p&gt;&#xA;&lt;p&gt;Seriously, 99% of the people won't even get their parachute on (correctly) in that amount of time, much less the &lt;strong&gt;far less&lt;/strong&gt; time that they would really have before they knew about the crash.&lt;/p&gt;&#xA;&lt;p&gt;The reality of the matter is that the pilots are doing everything possible in an emergency situation to &lt;strong&gt;not crash in the first place&lt;/strong&gt;, and if they are successful (which they usually are) then having everybody jump would have caused many more problems than having the passengers stay put in their seats with their seatbelts on.  In this particular crash, the pilots didn't even realize that the crash was certain until four seconds before impact when one of the pilots verbally stated &amp;quot;we're going to crash&amp;quot;.  Up until that point they were focused on recovering the aircraft and probably would never even have given the evacuation order had it even been available.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Gol Transportes Aéreos Flight 1907&lt;/h1&gt;&#xA;&lt;p&gt;This was the mid air collision over Brazil.  At least in this case, it became certain pretty fast that the aircraft was out of control and was going to crash.&lt;/p&gt;&#xA;&lt;p&gt;A small quote from the &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/546.pdf&quot; rel=&quot;noreferrer&quot;&gt;accident report&lt;/a&gt; describes what happened immediately after the collision:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Immediately after the collision, PR-GTD started a fast descending&#xA;spiral, similar to the  maneuver known as spin, which by no means&#xA;could be recovered or controlled by the crew.  During the vertiginous&#xA;dive, the aircraft was submitted to extreme aerodynamic forces,&#xA;around all the axes, with positive and negative accelerations, well&#xA;above the maximum  resistance limits of the operational envelope. As a&#xA;result, there was an in-flight break-up of the aircraft in several&#xA;pieces of different sizes, which hit the ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The increased G forces on the airplane were very likely to the point that people couldn't stand, or at the very least would have a &lt;strong&gt;much&lt;/strong&gt; harder time doing so.  Trying to put a parachute on in these circumstances would be even harder than in the previous example.  Total time from the mid air until impact with terrain:  Estimated 1 minute 5 seconds.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Each of these scenarios assume that even if there were parachutes on board and people were able to don them correctly in time, that they would be able to use them to survive. Here are a few additional factors that would come into play in the unlikely event that they were able to even get to this point:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Many modern aircraft doors can not be opened in flight.&lt;/li&gt;&#xA;&lt;li&gt;If this happened at high altitudes, everybody would need oxygen as well or they would pass out.&lt;/li&gt;&#xA;&lt;li&gt;The passengers that actually make it out of the airplane do not know how to fall in a stable position, and the parachute is &lt;strong&gt;very&lt;/strong&gt; likely to become tangled while opening as they are tumbling through the air.&lt;/li&gt;&#xA;&lt;li&gt;The passengers would need to actually deploy the parachute manually while most probably in a panicked state of mind.&lt;/li&gt;&#xA;&lt;li&gt;There would be many injuries during landing.&lt;/li&gt;&#xA;&lt;li&gt;Once they did land, they would have no survival gear.  This is particularly a problem over the open ocean or in the jungle (where these flights have been).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Considering that even in most accidents the aircraft is still landed in a &lt;em&gt;somewhat&lt;/em&gt; stable manner and most people survive, having a couple hundred people bailing out of an aircraft would most likely cause more harm than good, even if they could solve all of the technical issues.  If the decision is made to evacuate and then the pilots get the aircraft back under control, it would be even worse!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-12T21:16:11.893" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2211" PostTypeId="2" ParentId="2170" CreationDate="2014-03-12T22:23:58.280" Score="10" Body="&lt;p&gt;The key to recovering from a flat spin is partly in the aircraft's design (aerobatic aircraft are built to handle &quot;flatter&quot; spins than normal aircraft and recover more readily), partly in the loading (specifically the location of the center of gravity), and partly in how &quot;flat&quot; the spin actually is.&lt;br&gt;&#xA;There is going to be a point for any aircraft where you simply don't have the control authority to recover though (absent something extreme like mounting JATO bottles to the wing and firing them opposite the direction of the spin to stop the rotation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are definitely instances where pilots have been able to recover from a flat spin though - one example being is &lt;a href=&quot;http://www.piperowner.org/articles/close-calls/264-close-calls-surviving-a-flat&quot;&gt;the Piper Owner story&lt;/a&gt; Jay Carr pointed out. Aircraft can sometimes even recover on their own, such as the &lt;a href=&quot;https://www.youtube.com/watch?feature=player_embedded&amp;amp;v=3M2XZEYqIpQ&quot;&gt;&quot;cornfield bomber&quot;&lt;/a&gt; which actually &lt;em&gt;recovered itself&lt;/em&gt; after the pilot ejected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't locate the article, but I recall early in my training reading a story about an instructor and student who entered an inadvertent spin while practicing stalls. The spin went flat, and they were only able to recover by literally climbing forward onto the glare shield to move the center of gravity far enough forward that the nose dropped and normal spin recovery procedures were effective.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for avoiding flat spins, they're best avoided by avoiding spins entirely, and by applying prompt and correct recovery inputs if a spin is inadvertently entered (spins tend to &quot;go flat&quot; as they progress, so recovering early minimizes the risk of a &quot;regular&quot; spin going flat).&lt;br&gt;&#xA;How easy that recovery is depends on the aircraft's loading (center of gravity) - as illustrated by the &quot;climb onto the glare shield&quot; example above.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-12T22:30:12.867" LastActivityDate="2014-03-12T22:30:12.867" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2213" PostTypeId="2" ParentId="2185" CreationDate="2014-03-13T00:18:35.600" Score="32" Body="&lt;p&gt;Much like water, exposing fuel to below freezing temperatures does not instantly make it freeze.  It takes some amount of time, and as long as the fuel is not exposed to below freezing temperatures long enough to make it freeze, it won't be a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much time?  That depends on a number of factors like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Type of fuel&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jet A (common in the US) has a freezing point of -40 C&lt;/li&gt;&#xA;&lt;li&gt;Jet A1 (common outside the US) has a freezing point of -47 C&lt;/li&gt;&#xA;&lt;li&gt;Jet B (common for some military aircraft and very cold airports) has a freezing point of -60 C&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Initial fuel temperature&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you fuel in the middle east during the middle of summer, the fuel will be a lot warmer than when you fuel in Siberia in the middle of winter.  Warmer fuel will take longer to freeze.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Outside air temperature&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Much like trying to freeze water to form an ice cube, the colder the air around it, the faster that it will freeze.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Aircraft speed&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The faster that the airplane goes, the more friction there is as the air flows over the wing.  This heats up the air close to the wing and makes it take longer for the fuel to freeze (see previous point).  The temperature at the wing is known as TAT:&lt;/li&gt;&#xA;&lt;li&gt;For example, at an actual temperature of -56.5 C (SAT) and Mach 0.72 the TAT is -34 C, but at Mach 0.80 the TAT is -29 C.&lt;/li&gt;&#xA;&lt;li&gt;For more information about SAT -vs- TAT, see my answer about &lt;a href=&quot;https://aviation.stackexchange.com/a/1796/69&quot;&gt;Air Data Computers&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Quantity of fuel&lt;/strong&gt; &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Much like a small pond will freeze before a large lake, in order to get fuel to freeze you need to lower the temperature of all of it.  &lt;/li&gt;&#xA;&lt;li&gt;The more that there is, the longer it will take.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Aircraft design&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some aircraft run hydraulic lines close to the fuel so that the heat will help slow down the freezing.&lt;/li&gt;&#xA;&lt;li&gt;Some aircraft constantly pump fuel to keep it moving and mixing if it tends to freeze in one part of the tank before the rest&lt;/li&gt;&#xA;&lt;li&gt;Some aircraft use fuel to cool the engine oil using a heat exchanger, and return the warmed fuel to the tanks&lt;/li&gt;&#xA;&lt;li&gt;Many other design factors&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, fuel will not freeze in the typical amount of time that an aircraft is aloft.  If particular routes pose a problem, there are several options that the operator and pilot have:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Use a fuel with a lower freezing point&lt;/li&gt;&#xA;&lt;li&gt;Fly at a lower altitude where it is not as cold&lt;/li&gt;&#xA;&lt;li&gt;Choose a route with warmer temperatures&lt;/li&gt;&#xA;&lt;li&gt;Increase the speed of the airplane&lt;/li&gt;&#xA;&lt;li&gt;Carry extra fuel&lt;/li&gt;&#xA;&lt;li&gt;Transfer fuel in a way to keep fuel warmer.  Typically this is done by transferring fuel from the relatively warm fuselage tanks to the wing tanks which are exposed to more of the cold air.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-06-22T19:29:34.860" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2215" PostTypeId="2" ParentId="2170" CreationDate="2014-03-13T02:30:46.107" Score="5" Body="&lt;p&gt;Every airplane type has it'd own unique way of spinning. It can happen to also have an irregular spin path with a partial flat spin.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a flat spin, you almost have no authority on the controls, but the center of gravity (CoG) in a forward position (all planes are usually designed in that way) will convert the flat spin into a dive spin and so by gaining again authority on the rudder you can exit from the spin sooner.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the higher weight in the forward position together with gravity being the main cause of converting a flat spin into a dive spin. Most modern light planes are designed to automatically exit from a spin, even without any action from the pilot. It is also quite simple to exit a spin, but how varies from plane to plane. Usually, you put full rudder against the spin direction, push the stick slowly forward a bit and wait. Aerobatic planes enjoy doing spins without any extra risks compared to normal flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real problem is the high loss of altitude while waiting to exit from the spin. The plane will have a high vertical speed, so the danger comes from if there isn't enough altitude at the start of spin. A spin while landing is usually deadly. With unlimited altitude, every plane mathematically would exit sooner or later from any kind of spin, simply due to air friction, but this is theory since altitude is always quite limited.&#xA;Another problem for spins, is that you may not realize that you are spinning at all and so take wrong actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military jets are different. They are built to be dynamically unstable for better reactivity. I don't know much about them. Still, with a CoG in a forward position, they too, should convert a flat spin into a dive spin. The main problem is still enough altitude. A few rotations may be all you have before reaching the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To intentionally enter a spin, you need low speed; it's a stall condition of only one wing, which will drop, starting an auto-rotation which then converts to a spin. All this can be easily avoided with enough speed. Even if the engines are dead, you can always glide to the ground at the speed you wish.&lt;/p&gt;&#xA;" OwnerUserId="1417" LastEditorUserId="2171" LastEditDate="2014-09-14T23:57:45.467" LastActivityDate="2014-09-14T23:57:45.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2216" PostTypeId="1" CreationDate="2014-03-13T02:59:35.950" Score="7" ViewCount="3822" Body="&lt;p&gt;I hope this is a relevant place for me to ask a math question regarding aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am trying to understand how one would implement a controller to control the pitch angle of an airplane for a small exercise. I understand the control part and its implementation. What I do not grasp is how one acquires the longitudinal equations of motions (which are then used for the control part) which serves as the starting point. What is the starting point or what are the principles used to derive these equations? If I know how to derive these equations for a very simple case, then I know I have to linearize the equations and then apply control theory to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, how are the left and right hand sides of eq. 4.70 from pp. 164 of the following book book is derived?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will appreciate a simple explanation of the above case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;I am attaching two screen shots of two sets of equations from two sources. Links to the books are included below. Both sources state these are longitudinal equations of motion although their general form differ from each other.&lt;/li&gt;&#xA;&lt;li&gt;I think I got to understand one point: these equations were derived considering translation motion on the x and z planes and rotation about the y axis (so stated in the first book) Thereafter, I don't understand the procedure.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;1st set of equations from book 1:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/tAfqI.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;second set of equations from source 2:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Y3unh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;&lt;a href=&quot;http://books.google.co.jp/books?id=a_c2V0zAFwcC&amp;amp;pg=PA164&amp;amp;lpg=PA164&amp;amp;dq=longitudinal%20equations%20of%20motion%20of%20an%20aircraft&amp;amp;source=bl&amp;amp;ots=ZEbXbQyxBd&amp;amp;sig=bN5U9Cj6JIIVaspPMEcYVFWGxeE&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=cBohU8y7DofjkgWslYHgBQ&amp;amp;sqi=2&amp;amp;ved=0CEUQ6AEwBA#v=onepage&amp;amp;q=longitudinal%20equations%20of%20motion%20of%20an%20aircraft&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;book1: pg. 164 of Morris, Introduction to Aircraft Flight Mechanics: Performance, Static Stability  &lt;/a&gt;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;&lt;a href=&quot;http://www.dept.aoe.vt.edu/~lutze/AOE3134/LongitudinalDynamics.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source 2: pg 3 of this online note&lt;/a&gt;&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1420" LastEditorUserId="19" LastEditDate="2016-08-12T11:12:12.000" LastActivityDate="2016-08-12T11:12:12.000" Title="How to start deriving longitudinal equations of motion for an aircraft?" Tags="&lt;aircraft-design&gt;&lt;theory&gt;&lt;flight-dynamics&gt;" AnswerCount="2" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2217" PostTypeId="2" ParentId="2186" CreationDate="2014-03-13T03:24:12.517" Score="5" Body="&lt;p&gt;From basic high school physics, assume someone is 1.7m tall and steps out the plane rather than 'diving'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Distance~(from~standstill)=\frac12Acceleration\times{Time}^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And substituting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$1.7m=0.5\times9.8m/s2\times{t}^2=0.59s$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The panicked passenger would take 0.59 s for his head to be safely clear of any decapitating wires that happen to be level with the bottom of the door. If he immediately decelerated to 0 mph forward motion (I need someone else to figure out that part) he goes backwards 130 meters before he has dropped to safety. But even if it takes him 0.4 s to decelerate, that still leaves 0.19 s stationary in relation to the plane when his head isn't safe. That is about 42 meters, not counting the distance traveled while he is slowing down during those 0.4 s so I'm inclined to support @reirab on this one.&lt;/p&gt;&#xA;" OwnerUserId="1421" LastEditorUserId="97" LastEditDate="2014-04-18T03:21:48.487" LastActivityDate="2014-04-18T03:21:48.487" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2218" PostTypeId="2" ParentId="1997" CreationDate="2014-03-13T03:48:29.887" Score="13" Body="&lt;p&gt;Lets start with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ea5a30236d12e2cd77c464f3f9669b86&amp;amp;node=14:3.0.1.1.11.2.3.40&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.125&lt;/a&gt;, which defines security requirements for part 135 flights:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§135.125&lt;/strong&gt;   Aircraft security.&lt;/p&gt;&#xA;&lt;p&gt;Certificate holders conducting operators conducting operations under this part must comply with the applicable security requirements in &lt;strong&gt;49 CFR chapter XII&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;We pass the ball to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e5438e1e9a4d4df8db77bd0d62bb6bc5&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5&quot; rel=&quot;noreferrer&quot;&gt;49 CFR 1544&lt;/a&gt; and make sure we're in the right place:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§1544.1&lt;/strong&gt;   Applicability of this part.&lt;/p&gt;&#xA;&lt;p&gt;(a) This part prescribes aviation security rules governing the following:&lt;/p&gt;&#xA;&lt;p&gt;(1) The operations of aircraft operators holding operating certificates under 14 CFR part 119 for scheduled passenger operations, public charter passenger operations, private charter passenger operations; the operations of aircraft operators holding operating certificates under 14 CFR part 119 operating aircraft with a maximum certificated takeoff weight of 12,500 pounds or more; and other aircraft operators adopting and obtaining approval of an aircraft operator security program.&lt;/p&gt;&#xA;&lt;p&gt;(b) As used in this part, “aircraft operator” means an aircraft operator subject to this part as described in &lt;strong&gt;§1544.101&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For brevity, I'm not posting &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e5438e1e9a4d4df8db77bd0d62bb6bc5&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5#49:9.1.3.5.11.2.10.1&quot; rel=&quot;noreferrer&quot;&gt;1544.101&lt;/a&gt; which defines a host of paragraphs you must comply with depending on your operation.  If we assume a charter operation in an airplane weighing over 12,500 lbs, we get (1544.101(e)(1)):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(1) The requirements of §§1544.215, 1544.217, 1544.219, 1544.223, 1544.230, 1544.235, &lt;strong&gt;1544.237&lt;/strong&gt;, 1544.301(a) and (b), 1544.303, and 1544.305; and in addition, for all-cargo operations of §§1544.202, 1544.205(a), (b), (d), and (f).&lt;/p&gt;&#xA;&lt;p&gt;(2) Other provisions of subparts C, D, and E that TSA has approved upon request.&lt;/p&gt;&#xA;&lt;p&gt;(3) The remaining requirements of subparts C, D, and E when TSA notifies the aircraft operator in writing that a security threat exists concerning that operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From here the one we care about is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e5438e1e9a4d4df8db77bd0d62bb6bc5&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5#49:9.1.3.5.11.3.10.22&quot; rel=&quot;noreferrer&quot;&gt;1544.237&lt;/a&gt;, which says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§1544.237&lt;/strong&gt;   Flight deck privileges.&lt;/p&gt;&#xA;&lt;p&gt;(a) For each aircraft that has a door to the flight deck, each aircraft operator must restrict access to the flight deck as provided in its security program.&lt;/p&gt;&#xA;&lt;p&gt;(b) This section does not restrict access for an FAA air carrier inspector, an authorized representative of the National Transportation Safety Board, or for an Agent of the United States Secret Service, under 14 CFR parts 121, 125, or 135. This section does not restrict access for a Federal Air Marshal under this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Which brings us to our answer: &lt;strong&gt;YES&lt;/strong&gt;, a passenger may occupy the jumpseat if you do not have a door, and also if you do have a door as long as your company security program allows it.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-16T23:56:23.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2219" PostTypeId="2" ParentId="2198" CreationDate="2014-03-13T04:18:39.283" Score="3" Body="&lt;p&gt;Actually I don't think it's terribly difficult to implement technically. Of course getting regulators and airlines on board - and dealing with security and privacy issues are other matters entirely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have pointed out there are existing satellite data networks (e.g. Iridium and Inmarsat) that can be used to transmit location information &quot;back to base&quot;. The field terminal equipment for these networks isn't particularly power hungry either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Infact a company I did a bit of work with in the past (on another project) sells a system exactly like that right now, which is designed for helicopters and small aircraft. They're not a big company, so I'd lay odds that they have competitors in this field too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.indigosat.com&quot; rel=&quot;nofollow&quot;&gt;https://www.indigosat.com&lt;/a&gt; has details of their particular system.&lt;/p&gt;&#xA;" OwnerUserId="1422" LastEditorUserId="1422" LastEditDate="2014-03-13T04:24:47.970" LastActivityDate="2014-03-13T04:24:47.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2220" PostTypeId="1" AcceptedAnswerId="2463" CreationDate="2014-03-13T08:49:35.397" Score="18" ViewCount="2278" Body="&lt;p&gt;Since a very large sum of your ticket goes to airport tax, I was wondering how do they justify it and what is it used for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take your tax paid on your ticket and multiply it with the number of seats on that airplane and you realise that, per flight, the airports are receiving a substantial amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it all going to the government?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is very 'general' and just to get a loose idea of what the tax goes for. To get detailed information of every country is unnecessarily complex.&lt;/p&gt;&#xA;" OwnerUserId="659" LastEditorUserId="659" LastEditDate="2014-07-01T07:50:21.863" LastActivityDate="2014-07-06T04:51:10.887" Title="What is airport tax used for?" Tags="&lt;airport&gt;&lt;cost&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2221" PostTypeId="1" AcceptedAnswerId="2222" CreationDate="2014-03-13T09:03:22.327" Score="13" ViewCount="1339" Body="&lt;p&gt;What is the black pod starboard of the front landing gear on this F-16-I? At first I thought that it was a laser finder, but upon closer inspection it seems to resemble some type of short cannon. What might it be?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5ivvs.jpg&quot; alt=&quot;F-16&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="97" LastEditDate="2014-05-03T17:26:13.967" LastActivityDate="2014-05-03T17:26:13.967" Title="Is this an external cannon on an F-16?" Tags="&lt;military&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2222" PostTypeId="2" ParentId="2221" CreationDate="2014-03-13T09:09:58.990" Score="18" Body="&lt;p&gt;What you seem to have found is the &lt;strong&gt;Litening Targeting Pod&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Northrop Grumman's widely fielded LITENING system is a combat proven,&#xA;  self-contained, multi-sensor targeting and surveillance system.&#xA;  LITENING enables aircrews to detect, acquire, auto-track and identify&#xA;  targets at extremely long ranges for weapon delivery or nontraditional&#xA;  intelligence, surveillance and reconnaissance missions. &lt;a href=&quot;http://www.northropgrumman.com/Capabilities/litening/Pages/default.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://media.defenceindustrydaily.com/images/ELEC_LITENING-AT_on_F-16C_lg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;pod http://media.defenceindustrydaily.com/images/ELEC_LITENING-AT_on_F-16C_lg.jpg&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F16 does have a cannon as well, but it's located on the port side under and aft of the canopy: &#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/2/25/F16cannon.JPG&quot; alt=&quot;cannon&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.810" LastActivityDate="2014-03-13T09:09:58.990" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2223" PostTypeId="2" ParentId="2186" CreationDate="2014-03-13T10:13:32.807" Score="81" Body="&lt;p&gt;Qualification: I worked at a sport parachute center as an instructor for 10 years and I hold an FAA Master Parachute Rigger certificate. I believe that qualifies me as an expert on the subject.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The majority of the &lt;strike&gt;above&lt;/strike&gt; other statements here are correct. In summary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The door of a pressurized passenger plane cannot be opened in flight for the stated reasons.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the door of most larger passenger planes cannot be opened in flight after you depressurize the cabin because they swing forward. Push a sheet of plywood against a thunderstorm-grade wind and see how well you do. Now multiply the wind speed by 5.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;even if you blow the door out with explosives, the chances of an orderly exit are slim. At airliner speeds an orderly exit is critical if you expect to survive the jump. Street clothes will be torn to shreds. Oh, and it's COLD up there.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;you cannot depressurize an aircraft over 12,000 feet altitude without the passengers passing out rather quickly. If you can control the plane down to this altitude, you don't need the parachutes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;it is &lt;em&gt;extremely&lt;/em&gt; difficult to exit an unstable aircraft that is built for sport parachuting (in-flight door, suitable handles, door already open). If the plane is spinning and you are beside the door you might get tossed out and then struck by other parts of the airframe. If it's a larger plane and the door (or you) are away from the current axis of rotation, good luck. Yes, jumpers have successfully exited a crippled jump plane. None of them want to try it again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;modern sport parachutes use steerable ram-air canopies. Jump one of these without any training and you will hurt yourself landing. Most emergency parachutes are round. Jump one of those without any training and you &lt;em&gt;will&lt;/em&gt; break something when you land. 200 untrained people jumping ram-air canopies all at once will result in a number of collisions and entanglements, which are typically fatal for all involved.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;exiting an airplane below 1000 feet is really not practical. I would do it IF a) the plane is currently under control; b) landing is not practical; c) It's really 1000 feet, not less; d) I'm sitting beside the door. Possible scenario is the engine goes boom and I know there's nothing but rocky land ahead of us. Of course my gear is already on my back ready to go, and I know how to use it. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There have been many cases of a jump plane experiencing engine problems on the way up. By the time the pilot turns around, the cabin is usually empty. There have also been cases where jump planes have crashed on takeoff. None of the (very experienced) jumpers on board thought about anything other than tightening the seatbelt. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Points I disagree with: (although they do not change the outcome)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Emergency parachutes (seat-pack types) are available for far less than sport rigs. Maybe $1,500 each. Weight around 8-10kg. Putting a purpose-built one on would be not much more complicated than a 4-point harness. This was seriously considered back in the 1950's - aircraft seats were designed with parachutes built in. Planes were neither pressurized nor fast back then. Think DC-3 era - the DC-3 makes a great jump plane, I have used one a few times.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;maintenance costs would be no more than the escape slides, flotation gear or other similar equipment. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1425" LastEditorUserId="891" LastEditDate="2014-03-15T13:40:20.320" LastActivityDate="2014-03-15T13:40:20.320" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2224" PostTypeId="2" ParentId="2220" CreationDate="2014-03-13T12:14:06.657" Score="5" Body="&lt;p&gt;There are many things which together make up the 'tax' listed on your ticket. And depending on the airline this may or may not be honest; many use the term to bulk up the final price from the list price (and then advertise the list price of course). For example, a &quot;fuel tax&quot; is a sum the airline adds to counter changes in fuel price from the moment the ticket price was set to the moment you board the flight. And the &quot;security tax&quot;, were that really a tax, then why do different airlines charge different amounts for the same departure/destination pair? There might be a tax component in it, but it's massively padded by the airline itself (and most of the rest will be not tax, but contract fees with their contractors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course some countries do charge taxes, but those are usually collected directly and not as part of the ticket.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="67" LastEditDate="2014-03-13T14:05:25.363" LastActivityDate="2014-03-13T14:05:25.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2225" PostTypeId="1" AcceptedAnswerId="13300" CreationDate="2014-03-13T12:41:44.383" Score="19" ViewCount="2614" Body="&lt;p&gt;On some &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Hunter&quot; rel=&quot;noreferrer&quot;&gt;Hawker Hunters&lt;/a&gt;, there is a zig-zag on the leading edge of the wing, as shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jlkwY.png&quot; alt=&quot;hawker hunter with zig zag on leading edge&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do only some Hawker Hunters have this feature, and what is it for?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="14897" LastEditDate="2019-09-10T18:50:36.667" LastActivityDate="2019-09-10T18:50:36.667" Title="What does the zig-zag pattern on Hawker Hunter's leading edge represent?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;hawker-hunter&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2226" PostTypeId="2" ParentId="2225" CreationDate="2014-03-13T13:24:43.750" Score="7" Body="&lt;p&gt;Cirrus incorporates this design into their wings as well. Quoting from &lt;a href=&quot;http://whycirrus.com/engineering/stall-spin.aspx&quot; rel=&quot;nofollow&quot;&gt;their site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The outboard section of the Cirrus wing flies with a lower angle of&#xA;  attack than the inboard section. When the inboard section, which&#xA;  produces much of the lift, stalls the outboard section, where the&#xA;  ailerons are, is still flying. The result is that a stalled Cirrus&#xA;  airplane can be controlled intuitively using aileron.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="21" LastEditorUserId="97" LastEditDate="2014-03-14T03:28:06.593" LastActivityDate="2014-03-14T03:28:06.593" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2228" PostTypeId="1" AcceptedAnswerId="2233" CreationDate="2014-03-13T11:43:38.887" Score="12" ViewCount="18782" Body="&lt;p&gt;While skydiving we have to jump from the airplane at a certain altitude above Earth. So if for some reason the parachute doesn't open, then will that person (or any object similar to a human body) fall to Earth or will it be incinerated/vanish in the sky due to air-friction in space before coming down to the Earth?&lt;/p&gt;&#xA;" OwnerUserId="1375" OwnerDisplayName="AmitG" LastEditorUserId="97" LastEditDate="2014-03-14T03:32:19.483" LastActivityDate="2019-01-11T03:56:01.787" Title="What happens if a parachute does not open while skydiving?" Tags="&lt;skydiving&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2229" PostTypeId="1" CreationDate="2014-03-13T13:47:07.367" Score="11" ViewCount="472" Body="&lt;p&gt;How does an airline facilitate in-flight calls for mobile phones?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would guess that over open water in flight calls are relayed by an on board link to a communications satellite.  Such a system would likely need to track the location of the aircraft.  The records from this system could provide tracking information that is not available from other sources.&lt;/p&gt;&#xA;" OwnerUserId="1433" LastEditorUserId="97" LastEditDate="2014-03-19T07:32:14.473" LastActivityDate="2015-03-02T21:35:36.210" Title="How do airliners facilitate in flight calls for mobile phones?" Tags="&lt;avionics&gt;&lt;passenger&gt;&lt;electronics&gt;&lt;cell-phone&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2231" PostTypeId="2" ParentId="2220" CreationDate="2014-03-13T14:02:36.037" Score="2" Body="&lt;p&gt;Airports may be managed by private entities (even private security agencies) and then airports themselves are expensive to maintain, so apart from leasing its space for shops/eateries etc, they charge every passenger a tax which they collect from each airline. Its the duty of the airline to collect taxes and reimburse it to the concerned authority (whether private or government but probably government).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But all &quot;taxes&quot; on the ticket are not taxes; as jwenting pointed out, the yq (or yr) component on the ticket is actually a &quot;tax&quot; levied by airlines at their discretion and is called fuel surcharge. Other &quot;tax&quot; components may be an ROE (Rate Of Exchange) component which helps airline absorb fluctuation in currency (if they are operating in the country having different currency from theirs).&lt;/p&gt;&#xA;" OwnerUserId="1435" LastEditorUserId="718" LastEditDate="2014-03-13T14:58:15.410" LastActivityDate="2014-03-13T14:58:15.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2232" PostTypeId="2" ParentId="2228" CreationDate="2014-03-13T14:02:45.257" Score="7" Body="&lt;p&gt;If they are unlucky enough to have a failure to deploy the parachute: They will probably hit the ground at approx 190 Km/h (120 Mph) in one piece. The unfortunate victim will most probably die instantly.&lt;/p&gt;&#xA;" OwnerUserId="693" LastActivityDate="2014-03-13T14:02:45.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2233" PostTypeId="2" ParentId="2228" CreationDate="2014-03-13T14:03:17.443" Score="35" Body="&lt;p&gt;The majority of the heat developed during reentry of a space-vehicle comes from air compression not friction. Remember, to go into space, you don't have to go very high, but to orbit you will have to &lt;a href=&quot;http://what-if.xkcd.com/58/&quot;&gt;go very &lt;em&gt;very&lt;/em&gt; fast&lt;/a&gt;, and it's not the fall that produces the heat, it's the slowing down part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you had a human fall without a chute, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_velocity&quot;&gt;terminal velocity&lt;/a&gt; (where air resistance cancels gravity and you continue downward at a constant speed) would be around 100-200 mph, not nearly enough to cause any kind of heat (or cars would burn up by going normal cruising speeds). To get higher terminal velocities, you'd have to go a lot higher, where the air is a lot less dense, higher than any skydiver have, and as far as I can tell &lt;a href=&quot;http://en.wikipedia.org/wiki/Felix_Baumgartner&quot;&gt;Felix Baumgartner&lt;/a&gt; did not experience any incineration during his jump.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The unfortunate skydiver will almost certainly die, but there'd definitely be a body, and it'll probably be in one piece.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="64" LastEditDate="2014-03-13T21:01:49.697" LastActivityDate="2014-03-13T21:01:49.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2234" PostTypeId="2" ParentId="2228" CreationDate="2014-03-13T14:03:35.010" Score="9" Body="&lt;p&gt;There is a spring-loaded backup chute that will auto-deploy when the jumper goes too fast and is below 2.5k feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that also fails, the jumper becomes a smear on the ground. Freefall speed (aka terminal velocity) is not fast enough to start any type of burn.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="97" LastEditDate="2014-03-14T03:33:53.973" LastActivityDate="2014-03-14T03:33:53.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2235" PostTypeId="2" ParentId="2225" CreationDate="2014-03-13T15:06:02.853" Score="6" Body="&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;: The hawker hurricanes wings are better describes as &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_extension#Dogtooth_extension&quot; rel=&quot;nofollow&quot;&gt;dogtooth extension&lt;/a&gt; as flyingfisch points out.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;These features are known as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_cuff&quot; rel=&quot;nofollow&quot;&gt;Leading edge cuff&lt;/a&gt; and aims to reduce spin tendencies by delaying the onset of stall.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-13T21:19:22.763" LastActivityDate="2014-03-13T21:19:22.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2236" PostTypeId="2" ParentId="2225" CreationDate="2014-03-13T15:11:52.600" Score="20" Body="&lt;p&gt;After doing a little more research I found the answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The zig-zag on the leading edge is a type of &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_extension&quot;&gt;leading edge extension&lt;/a&gt; called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_extension#Dogtooth_extension&quot;&gt;dogtooth extension&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quote from wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A dogtooth is a small, sharp zig-zag break in the leading edge of a&#xA;  wing. It is usually used on a swept wing, but also on straight wings&#xA;  (&quot;Drooped Leading Edge&quot; arrangement), to generate a vortex flow field&#xA;  to prevent separated flow from progressing outboard at high angle of&#xA;  attack. The effect is the same as a wing fence.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Where the dogtooth is added as an afterthought, as for example with&#xA;  the Hawker Hunter and some variants of the Quest Kodiak, the dogtooth&#xA;  is created by adding an extension to the outer section only of the&#xA;  leading edge.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-13T15:11:52.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2237" PostTypeId="2" ParentId="2220" CreationDate="2014-03-13T15:41:25.683" Score="2" Body="&lt;p&gt;If it is genuinely a &lt;strong&gt;tax&lt;/strong&gt;, it goes to the government. Other countries may be different but, in the UK, all money that the government receives from taxes goes to a central fund to be spent wherever it's needed: there's no mechanism for, say, the money from aviation-related taxes to be reserved for aviation-related spending, such as ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fees&lt;/strong&gt; and &lt;strong&gt;surcharges&lt;/strong&gt; are different and may go to the airport, the airline or whoever else charged them.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-03-13T15:41:25.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2238" PostTypeId="2" ParentId="2220" CreationDate="2014-03-13T15:52:50.247" Score="19" Body="&lt;p&gt;As jwenting pointed out, there isn't one &quot;airport tax&quot; - there's a whole bunch of them, and they're not all taxes (some are &quot;fees&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airlines.org/Pages/Government-Imposed-Taxes-on-Air-Transportation.aspx&quot;&gt;airlines.org has a list of the common ones you'll pay in the USA, and approximately what they cost you&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Broadly the taxes you're paying on airline tickets break down into two categories:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Taxes that fund the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/apl/aatf/&quot;&gt;Airport and Airway Trust Fund&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;These taxes pay for Air Traffic services (a little under half the operating butdget for ATC), maintenance of the airway infrastructure (radio navigational aids, RADAR sites, etc.), research and development to improve the airway infrastructure (e.g. &lt;a href=&quot;http://www.faa.gov/nextgen/&quot;&gt;NextGen&lt;/a&gt;), and to fund the Airport Improvement Program (which provides grants to airports, mainly to implement safety improvements).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual tax categories themselves break down further (again, airlines.org's breakdown is excellent).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fees that fund DHS programs&lt;/strong&gt;&lt;br&gt;&#xA;These are often called &quot;security taxes&quot;, and include things like the &quot;September 11&lt;sup&gt;th&lt;/sup&gt; fee&quot;, APHIS fees (for inspecting plants and livestock), and customs/immigration charges.&lt;br&gt;&#xA;Note that all of these are technically &lt;em&gt;fees&lt;/em&gt;, not &lt;em&gt;taxes&lt;/em&gt; -- these are only levied when a flight is using the services the fee is funding (or at least that's what's supposed to happen. In practice the airline is responsible for paying the appropriate fee as a cost of doing business. They can recoup that cost any way they'd like (typically they lump it in with &quot;taxes&quot; or itemize it out on the ticket rather than including it in the base fare, so they can advertise lower base fares).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What about the little planes?&lt;/strong&gt;&lt;br&gt;&#xA;General aviation doesn't pay &quot;ticket taxes&quot;, but that doesn't mean they get to escape paying for the infrastructure the flights are using. The government recognizes that the air traffic system costs money, and they like to ensure that the money is available.&lt;br&gt;&#xA;Accordingly there is a tax levied on all aviation fuel purchased in the US: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airlines currently pay about $0.04/gallon in taxes for the jet fuel they burn  &lt;/li&gt;&#xA;&lt;li&gt;Non-Airline flights burning jet fuel pay about $0.22/gallon in taxes&#xA;(the higher rate making up for the other taxes they're not paying)&lt;/li&gt;&#xA;&lt;li&gt;Piston-powered planes burning aviation gasoline pay $0.19/gallon in taxes&lt;br&gt;&#xA;(higher than what the airlines pay for jet fuel, but lower than the standard jet fuel tax because piston planes don't travel as far, and are thus less of a burden on the air transport system)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-13T18:43:33.937" LastActivityDate="2014-03-13T18:43:33.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2239" PostTypeId="2" ParentId="2229" CreationDate="2014-03-13T16:58:46.897" Score="11" Body="&lt;p&gt;Cribbing liberally from &lt;a href=&quot;https://aviation.stackexchange.com/a/2022/64&quot;&gt;Manfred's answer on a related question&lt;/a&gt;, it basically works like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://luckybogey.files.wordpress.com/2009/06/infographietelmobile_en.jpg&quot; alt=&quot;Cell phone / WiFi in the air&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airline contracts with a communication company and installs satellite transceivers and &lt;a href=&quot;http://en.wikipedia.org/wiki/Small_cell&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;small cell&quot; cellular equipment&lt;/a&gt; on their aircraft. Your phone talks to the on-board cellular equipment just like it would to a cell site on the ground, but the information is relayed to the satellite and sent back to earth to join the regular telephone/data networks.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's not generally feasible to use these datalinks to track the location of the aircraft -- getting your basic position (latitude/longitude) requires triangulation from at least 3 satellites, while data communication only requires one (satellites are expensive, so providers aren't likely to launch their own constellation of satellites to duplicate the functionality of GPS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This same type of data uplink &lt;em&gt;could&lt;/em&gt; theoretically be used to transmit flight data (including GPS position that the aircraft can get from the existing GPS equipment on board) back to the airline's headquarters, ATC (to fill gaps in RADAR coverage), etc., but I'm not aware of any system or plan to implement that currently.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-03-02T21:35:36.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2240" PostTypeId="2" ParentId="2225" CreationDate="2014-03-13T18:44:07.527" Score="5" Body="&lt;p&gt;As an added piece of information, this feature may have something to do with the fact that the Hawker Hunter, for many years, was the only swept wing fighter that could be reliably recovered from an inverted spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason the Empire Test Pilot School at Boscombe Down used one for advanced training purposes (and may still do so).&lt;/p&gt;&#xA;" OwnerUserId="1446" LastActivityDate="2014-03-13T18:44:07.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2241" PostTypeId="1" AcceptedAnswerId="2244" CreationDate="2014-03-13T19:28:48.957" Score="26" ViewCount="9813" Body="&lt;p&gt;Runway 15 at DCA (Reagan National) is closed at night and other times. By &quot;closed,&quot; I mean that airport management places a gigantic lit/flashing &quot;X&quot; in the landing zone of 15. I'd estimate the big &quot;X&quot; is 8 by 8 feet, at least. It's like one of those roadside trailer flashing signs, except it's a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flashing X is very evident to pedestrians, bikers, etc., on the Mount Vernon trail. It's not some bizarre national secret.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question: Why, in the tightly controlled airspace of Washington, DC, would DCA need to roll out a giant lit &quot;X&quot; to keep planes from landing there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As if the obstruction were not there, you could fly in? That doesn't calculate, given how tight the airspace is controlled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does this airport in the center of the world's highest airspace security roll out a construction trailer with a big X to keep planes from landing there?&lt;/p&gt;&#xA;" OwnerUserId="1448" LastEditorUserId="1696" LastEditDate="2015-02-14T23:41:33.120" LastActivityDate="2015-02-14T23:41:33.120" Title="Why is a large flashing &quot;X&quot; placed on a closed runway at Reagan National Airport?" Tags="&lt;runways&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2243" PostTypeId="2" ParentId="2241" CreationDate="2014-03-13T19:45:07.040" Score="15" Body="&lt;p&gt;Any time that a runway is closed, it is marked as such by an X on the runway so that pilots will know, visually from the air.  At night it is lighted.  This is an additional measure that is used to help protect people and equipment on the ground along with the aircraft if a pilot were to make a mistake and land on the wrong runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is even more important than normal at this particular airport because the runway threshold for runway 19 is very close to that of 15 and they are on similar headings.  The Jeppesen airport diagram even includes a note which says &quot;Be advised some aircrews mistake runway 15 for runway 19&quot; (although the one below doesn't include this note).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YE8Qi.png&quot; alt=&quot;KDCA&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-13T20:02:35.227" LastActivityDate="2014-03-13T20:02:35.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2244" PostTypeId="2" ParentId="2241" CreationDate="2014-03-13T19:51:18.100" Score="26" Body="&lt;p&gt;The standard way of marking a runway as &quot;CLOSED&quot; is to put a big giant &lt;code&gt;X&lt;/code&gt; on it - for fields which operate at night that &lt;code&gt;X&lt;/code&gt; needs to be lighted. The specifications for the runway closure marker are outlined in an &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22296&quot; rel=&quot;noreferrer&quot;&gt;FAA advisory circular (AC 150/5345-55A)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of the marker is to indicate that the runway is temporarily closed (either administratively, as is the case at DCA, or for construction/repair/maintenance).  It is redundant with air traffic control measures (such as NOTAMs) indicating that the runway is out of service, in case some pilots didn't check NOTAMs or somehow managed to stumble into the airspace and happen upon the airport while it's closed.  (Obviously in the case of DCA they would have &lt;em&gt;other&lt;/em&gt; problems were they to wander blindly into the area without talking to anyone, but believe it or not it happens far more often than any of us would like.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The big flashing &lt;code&gt;X&lt;/code&gt; doesn't &quot;stop&quot; you from landing on the runway - it just tells you you really, &lt;em&gt;really&lt;/em&gt; shouldn't be landing there. &lt;a href=&quot;http://www.avweb.com/avwebflash/news/FOIA_inhofe_audio_recording_landing_closed_runway_new_information_204485-1.html&quot; rel=&quot;noreferrer&quot;&gt;There is a United States Senator who has achieved some notoriety in the aviation community after landing on a closed runway&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;code&gt;X&lt;/code&gt; is also quite a bit bigger than you think it is to ensure it's visible from the air  (the arms are 14 feet long):&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2bSei.jpg&quot; alt=&quot;Runway Closure Marker&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I was looking for a good aerial photo of one at night, but unfortunately couldn't locate one. The intent is for the &lt;code&gt;X&lt;/code&gt; to be about the same size as runway numbers so there's no good reason for a pilot to not see it.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-13T19:51:18.100" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2246" PostTypeId="2" ParentId="2241" CreationDate="2014-03-13T20:20:50.577" Score="13" Body="&lt;p&gt;This is particularly important at DCA because aircraft landing on runway 19 will either by flying the LDA 19 or River Visual 19 approaches if landing to the south.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at these approaches:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Pqs8.png&quot; alt=&quot;River 19 DCA&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/n9TuZ.png&quot; alt=&quot;LDA 19&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll notice that you approach the airport lined up with runway 15 until very close in when you follow the river and turn for runway 19.  Having flown into this airport a number of times, it is easy to misidentify the runway if you are unfamiliar.  Putting a big X on the runway when it is closed increases the situational awareness and helps identify the proper runway.  You'll note in both procedures you must be flying visually to make the turn and identify runway 19, neither approach lines you up for that runway.  There is no straight-in for runway 19.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-13T20:20:50.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2247" PostTypeId="2" ParentId="2228" CreationDate="2014-03-13T21:38:00.340" Score="-5" Body="&lt;p&gt;Well, if you skydive in pairs, which as I understand is recommended, and if you catch the error &lt;strong&gt;before&lt;/strong&gt; your partner opens his/her chute, you could signal to them that your equipment is not in working order, and then you could essentially bear hug them while they open their chute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is obviously not ideal and could even dislocate the shoulders of the skydiver whose chute did not open.&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2014-03-13T21:38:00.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2248" PostTypeId="1" AcceptedAnswerId="2251" CreationDate="2014-03-13T22:08:06.057" Score="28" ViewCount="6742" Body="&lt;p&gt;It seems like at this point it would be game over, since the spinning rotor is the only thing keeping it in the air. Is there any way to land a helicopter in this condition without crashing?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="69" LastEditDate="2014-03-15T04:46:42.850" LastActivityDate="2019-01-07T15:11:00.383" Title="What happens when a helicopter loses an engine?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2249" PostTypeId="2" ParentId="2248" CreationDate="2014-03-13T22:27:50.633" Score="23" Body="&lt;p&gt;Many helicopters have more than one engine driving the rotor system.  On those, losing an engine is probably less serious than it would be in a single-engine craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All helicopters that I'm aware of are capable of &lt;a href=&quot;http://en.wikipedia.org/wiki/Autorotation_%28helicopter%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;autorotation&lt;/a&gt;.  In an autorotation, the pilot uses the air rushing up through the rotor disk to keep the blades spinning. This involves changing the collective angle of attack of the blades to near zero to minimize drag, plus some other control inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While doing this, the pilot is trading potential energy (altitude) for kinetic energy (keep the rotors spinning).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Immediately prior to landing, the pilot changes the collective angle of attack of the rotors back to the normal &quot;push air down&quot; setting. This rapidly slows the rotors, but if done correctly there's enough cushion to land the vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a much more detailed description of how to execute an auto-rotation landing, &#xA;see &lt;a href=&quot;https://aviation.stackexchange.com/q/14605/52&quot;&gt;How does a helicopter pilot execute an auto-rotation landing?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per FAR 61.87(f)(15), A student pilot who is receiving training for a helicopter rating must receive and log flight training for the following maneuvers and procedures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...&#xA;(15) Simulated emergency procedures, including autorotational descents with a power recovery and power recovery to a hover;&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-30T19:30:47.257" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2250" PostTypeId="1" AcceptedAnswerId="2253" CreationDate="2014-03-13T23:30:56.633" Score="7" ViewCount="667" Body="&lt;p&gt;In the last year, I have had to undergo bypass surgery. I am fully recovered now (and past the mandatory 6-month waiting period), but have just been apprised by my AME that my 3rd class medical deferral is likely to take a month or two for the FAA to process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am also in a partnership, and our insurance requires annual recurring training. Normally, all four of us (partners) take the recurring training at the same time, and get a discounted rate as a result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As fate would have it, this year's recurring training will fall into the time I am waiting to hear back from the FAA. Since the flight portion of the recurring training (essentially an IPC) is conducted under the supervision of a CFII, can I complete it without a current medical certificate?&lt;/p&gt;&#xA;" OwnerUserId="1455" LastActivityDate="2014-03-14T02:21:11.713" Title="Can a private pilot receive recurring training while waiting for a special-issuance medical approval?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2251" PostTypeId="2" ParentId="2248" CreationDate="2014-03-14T00:22:28.003" Score="37" Body="&lt;p&gt;Helicopters are able to do something called &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Autorotation_%28helicopter%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;autorotation&lt;/a&gt;&lt;/strong&gt; if all thrust is lost. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In a helicopter, an autorotative descent is a power-off  maneuver in&#xA;  which the engine is disengaged from the main  rotor system and the&#xA;  rotor blades are driven solely by the  upward flow of air through the&#xA;  rotor. In other  words, the engine is no longer&#xA;  supplying power to the main  rotor. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.todayifoundout.com/wp-content/uploads/2012/05/auto-rotation.jpg&quot; alt=&quot;heli&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Look in particular at the direction of flight arrows. Remember there's a lift vector coming of the blades as well in both cases.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the collective is decreased immediately when thrust is lost for whatever reason. This allows the airflow coming through the blades to push them around, like a reverse windmill in a way, keeping the blades spinning. This also generates lift, keeping the helicopter generating some lift (while descending of course). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At the instant of engine failure, the main rotor blades are &#xA;  producing lift and thrust from their angle of attack (AOA) &#xA;  and velocity. By lowering the collective pitch, which must be &#xA;  done immediately in case of an engine failure, lift and drag &#xA;  are reduced, and the helicopter begins an immediate descent, &#xA;  thus producing an upward flow of air through the rotor &#xA;  system. This upward flow of air through the rotor provides &#xA;  sufficient thrust to maintain rotor rpm throughout the descent. &#xA;  Since the tail rotor is driven by the main rotor transmission &#xA;  during autorotation, heading control is maintained with the &#xA;  antitorque pedals as in normal flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Once the helicopter reaches ground, the pilot will pull up. Since the blades were spinning a bit faster than needed for a hover since he was flying forward the whole procedure, he simply pulls up and levels out carefully close to the ground until the helicopter touches down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This being said, you have to be careful, since if you're flying to slow you can't pull it off.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When landing from an autorotation, the only energy available &#xA;  to arrest the descent rate and ensure a soft landing is the &#xA;  kinetic energy stored in the rotor blades. Tip weights can &#xA;  greatly increase this stored energy. A greater amount of rotor &#xA;  energy is required to stop a helicopter with a high rate of &#xA;  descent than is required to stop a helicopter that is descending &#xA;  more slowly. Therefore, autorotative descents at very low or &#xA;  very high airspeeds are more critical than those performed &#xA;  at the minimum rate of descent airspeed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This dangerous conditions are shown in a height-velocity diagram as is seen below, in this case apparently &lt;a href=&quot;http://blog.aopa.org/helicopter/?p=653&quot; rel=&quot;nofollow noreferrer&quot;&gt;from an R44&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iB1MX.jpg&quot; alt=&quot;danger&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a little video to get an idea of how it looks for the pilot: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/yNWjW6yORyg?start=0&quot;&gt;&lt;/iframe&gt;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autorotation is often time critical and has to be done right as there's only one shot and as such is practised by pilots on a regular basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;All extracts in this section are from &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Helicopter Emergencies and Hazards&quot;&lt;/a&gt; by the FAA, an excellent and very extensive publication on the topic.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-07T15:11:00.383" LastActivityDate="2019-01-07T15:11:00.383" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2252" PostTypeId="1" AcceptedAnswerId="17436" CreationDate="2014-03-14T02:19:32.820" Score="21" ViewCount="12951" Body="&lt;p&gt;How do flying wings, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot;&gt;B-2 Stealth&lt;/a&gt; bomber, actually keep themselves from yawing out of control without a vertical stabilizer?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the record, I assume this has to be a simple mechanics process.  Why?  Well flying wings go all the way back to the 30s.  One of the earliest (and my personal favorite) is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_N-9M&quot;&gt;N-9M&lt;/a&gt;, which was a scale model of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_XB-35&quot;&gt;XB-35&lt;/a&gt;, a prototype bomber for the allies during WWII.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They didn't have flight control computers back then, and the only control complaints I recall them having is that early versions had a tendency to flip over backwards when approaching stall speeds, well, that and the ground effects were pretty strong. But, no mentions of going into flat spins when going into hard maneuvers (that I recall).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do they control that Y axis on flying wings?  Are they perhaps more susceptible to a flat spin than a regular design (even if those risks can be kept to an acceptable minimum)?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="23223" LastEditDate="2019-09-10T07:21:15.230" LastActivityDate="2021-04-20T16:07:54.007" Title="How does a flying wing keep from going into a flat spin when maneuvering?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;flight-controls&gt;&lt;flying-wing&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2253" PostTypeId="2" ParentId="2250" CreationDate="2014-03-14T02:21:11.713" Score="6" Body="&lt;p&gt;My understanding is that your medical is currently invalid (because you had bypass surgery and need to get your medical reinstated), so you currently cannot exercise the privileges of your certificate - i.e. you can't act as pilot in command of a flight (or any other required crew member in a role for which a medical is required).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Casey pointed out, you've got an out that allows you to still take training (and even to fly generally): Someone else with a valid medical and a certificate appropriate to the category &amp;amp; class of aircraft needs to act as the (legal, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.2&quot;&gt;FAR 91.3&lt;/a&gt;) pilot in command while you're operating the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your CFII is willing to accept that role (and the attendant liability) while giving you your training you can go up with them and complete the recurrent training your insurance company requires, but this is something you need to discuss with your CFI prior to going up with them.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-14T02:21:11.713" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2254" PostTypeId="1" AcceptedAnswerId="2262" CreationDate="2014-03-14T05:28:41.187" Score="4" ViewCount="3999" Body="&lt;p&gt;In the first part of &lt;a href=&quot;http://www.youtube.com/watch?v=5JpbZZKqxy0&quot; rel=&quot;nofollow noreferrer&quot;&gt;this YouTube video&lt;/a&gt;, you can see an aircraft supposedly flying 4x faster than the surrounding aircraft, at the time the Malaysian 777 went missing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After replaying this on Flight Radar 24, KAL672 departs Kuala Lumpa a short while before MAS370. It then does a 180, flies back towards the airport, then appears to do another 180 and rockets across the ocean:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Fl9tm.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the playback links for 2014-03-07 16:55: &lt;a href=&quot;http://www.flightradar24.com/2014-03-07/16:55/12x/KAL672/2d80fae&quot; rel=&quot;nofollow noreferrer&quot;&gt;KAL672&lt;/a&gt; and &lt;a href=&quot;http://www.flightradar24.com/2014-03-07/16:55/12x/MAS370/2d81a27&quot; rel=&quot;nofollow noreferrer&quot;&gt;MAS370&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, my question is, what is this oddity that FR24 is showing? (to ward off conspiracy theorist nuts).&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="64" LastEditDate="2014-04-04T21:10:45.097" LastActivityDate="2014-04-04T21:10:45.097" Title="What was Korean Air 672 doing at the time of Malaysia Air 370's disappearance?" Tags="&lt;accidents&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-03-14T17:17:17.680" ContentLicense="CC BY-SA 3.0" />
  <row Id="2256" PostTypeId="2" ParentId="2252" CreationDate="2014-03-14T06:41:30.433" Score="3" Body="&lt;p&gt;Flying wings use differential thrust for yaw control instead of vertical stabilizers and rudders. Some also have small outboard rudders or spoilers for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="110" LastActivityDate="2014-03-14T06:41:30.433" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2258" PostTypeId="1" CreationDate="2014-03-14T07:34:35.867" Score="14" ViewCount="1034" Body="&lt;p&gt;Non-precision instrument approaches generally have altitude restrictions which get lower when you get closer to the airport. I always figured these restrictions were AMSL using the current altimeter setting, not compensating for temperature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some have heard the mnemonic that mountains are higher come wintertime, which basically means that colder weather make your altimeter read higher than you actually are (or, as most pilots prefer to think, you're lower than what your altimeter reads)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a look at this VOR approach into Newark&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mpOIQ.png&quot; alt=&quot;IAP VOR RWY 11 at EWR&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most altitude restrictions are a minimum level, so you're free to fly higher if it's a particularly cold day. But have a look at LOCKI intersection, the final approach fix. That's at 1500 ft, not at-or-above. At -40, this will put you around 1100 ft above ground level. Although I don't see any obstructions that high during this segment of the approach, as far as I know instrument approaches are supposed to guarantee a 500 ft obstacle clearance, do procedures using this kind of restrictions have a minimum temperature?&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2017-09-25T14:48:42.517" Title="Do instrument approach procedures sometimes have a minimum temperature?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;density-altitude&gt;&lt;non-precision-approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2261" PostTypeId="2" ParentId="2258" CreationDate="2014-03-14T08:50:38.577" Score="12" Body="&lt;p&gt;There are procedures with temperature restrictions, related to altitude constraints. An example is Innsbruck: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ISa01.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ISa01.jpg&quot; alt=&quot;LOWI RNP AR&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The text in the red box says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Procedure N/A below AD temp -7°&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For effect of temperature on altimeter: &lt;a href=&quot;https://aviation.stackexchange.com/questions/43473/how-will-the-altimeter-read-in-air-colder-than-isa&quot;&gt;How will the altimeter read in air colder than ISA?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-09-25T14:48:42.517" LastActivityDate="2017-09-25T14:48:42.517" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2262" PostTypeId="2" ParentId="2254" CreationDate="2014-03-14T09:02:03.733" Score="4" Body="&lt;p&gt;With the way in which it suddenly switched back and forth it appears to be either a software glitch or bad data from one of the feeders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircraft displayed in yellow on FlightRadar24 are detected by volunteers with their own ADS-B receivers, of varying quality in hardware, software and range. When aircraft reach the very edge of someone's receiver range you can occasionally get corrupted data, perhaps showing the aircraft somewhere back along its path or far off it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another scenario is when a receiver is having trouble uploading its data to the FR24 servers because of a bad internet connection or similar, so position updates arrive later than they should.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes the FR24 servers get conflicting info, for the same reason, where one ADS-B feeder is providing good data and the other bad. When that happens you can see the plane seem to jump backwards and forwards until one of the receivers is out of range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's something I've seen fairly often, even with my own receivers. FR24 does try to filter the anomalies out but it's a difficult task.&lt;/p&gt;&#xA;" OwnerUserId="1263" LastActivityDate="2014-03-14T09:02:03.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2263" PostTypeId="1" AcceptedAnswerId="2264" CreationDate="2014-03-14T09:40:26.493" Score="25" ViewCount="67949" Body="&lt;p&gt;You always hear that the Boeing 737 have been flying for so many years and the Airbus A310 for that many years, but of course that include new airframes being produced all the time. What is the lifespan of one airframe on average in general use by airlines, before it is scrapped?&lt;/p&gt;&#xA;" OwnerUserId="659" LastActivityDate="2019-11-27T19:02:52.527" Title="What is the lifespan of commercial airframes (in general)?" Tags="&lt;aircraft-limitations&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2264" PostTypeId="2" ParentId="2263" CreationDate="2014-03-14T10:57:00.057" Score="22" Body="&lt;p&gt;Metal fatigue is normally the limiting factor of an aircraft's lifespan. Fatigue cracks build up every flight (at start &amp;amp; landing), called a cycle. Therefore the design life of an aircraft is typically given in cycles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SORHl.jpg&quot; alt=&quot;Metal fatigue&quot;&gt;&lt;br&gt;&#xA;Metal fatigue cracks, source: &lt;a href=&quot;https://www.boeing.com/commercial/aeromagazine/articles/2012_q4/2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For long haul aircraft, that make relatively few cycles, the design lifespan is in the order of 40 000 cycles. For short haul the number is higher, sometimes up to 111 000 cycles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the Boeing 747 has a design number of cycles of 35 000, the MD-80 has 110 000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft should be operable for about 30 years before reaching the cycle limit. The lifetime can be stretched by special inspection and maintenance programs.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2019-11-27T19:02:52.527" LastActivityDate="2019-11-27T19:02:52.527" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="2265" PostTypeId="2" ParentId="2228" CreationDate="2014-03-14T13:23:21.460" Score="32" Body="&lt;p&gt;Qualification: I worked at a sport parachute center as an instructor for 10 years and I hold an FAA Master Parachute Rigger certificate. I believe that qualifies me as an expert on the subject.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fastest a human can fall unassisted is about 300km/h (head-down dive). Far too slow for frictional or compressive heating. Fighter pilots have ejected at supersonic speeds and not warmed up any (it's also rather cold at higher altitudes). You would have to jump from the space station to incinerate yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the primary question, if parachute #1 doesn't open, you use parachute #2. If that doesn't work, you have about 10 seconds left. In consolation, it's not all that messy unless you are unfortunate enough to impact on pavement. An open-coffin service is usually possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To reply to other inaccuracies:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;the #2 parachute is not spring loaded, the small (1 meter) extraction parachute is. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;we don't depend on the &lt;del&gt;idiot box&lt;/del&gt; auto-activator. There's a handle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;skydiving in pairs is not &quot;recommended&quot; (that's scuba diving). You want to be very far away from other people when deploying parachute #1, and by then it's far too late for anyone else to help. The close-up videos you have seen are carefully planned in advance - the cameraman and subject agree on relative position and sequence, and the video subject deploys his parachute higher than usual. Videos you may have seen of several canopies together are also carefully planned in advance, and it's a lot harder than it looks.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;holding someone else during deployment is not possible. No one is strong enough to hang on during deceleration. It's not (normally) a shock but the forces involved are rather substantial. Backup parachutes DO open very quickly - at freefall speeds it's rather unpleasant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the &lt;strong&gt;exceptionally rare&lt;/strong&gt; cases of someone surviving without a parachute typically involve a steep slope and either deep snow or crushable foliage. Forget water - at 200km/h it's only slightly more forgiving than concrete.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1425" LastEditorUserId="22726" LastEditDate="2019-01-11T03:56:01.787" LastActivityDate="2019-01-11T03:56:01.787" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2266" PostTypeId="1" AcceptedAnswerId="2268" CreationDate="2014-03-14T13:39:05.063" Score="43" ViewCount="34995" Body="&lt;p&gt;These days, when reading news about missing Malaysia Airlines Boeing 777-200, I keep coming across a scenario where pilot might have deliberately turned off the transponder which is used for the communication of flight with ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is a possibility that any bad thing can happen when pilot turn off transponder, why would one give the ability of turning off the transponder to a pilot when he/she usually depends on instructions from ATC or flight control. Is there anyway that ATC can turn on transponder back from ground?&lt;/p&gt;&#xA;" OwnerUserId="1466" LastEditorUserId="19" LastEditDate="2015-01-12T19:52:23.880" LastActivityDate="2015-05-06T21:47:45.117" Title="Why do pilots have the ability to turn off the transponder in-flight?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;radio-communications&gt;&lt;radar&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2267" PostTypeId="2" ParentId="2266" CreationDate="2014-03-14T13:43:41.557" Score="22" Body="&lt;p&gt;Everything including the flight recorder has a power switch or circuit breaker. Electrical devices occasionally malfunction, and you don't want a sparky transponder setting the plane on fire when you can just turn it off and use the other one. &lt;/p&gt;&#xA;" OwnerUserId="1425" LastActivityDate="2014-03-14T13:43:41.557" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2268" PostTypeId="2" ParentId="2266" CreationDate="2014-03-14T13:44:45.780" Score="67" Body="&lt;p&gt;Basically everything that consumes power on an aircraft can potentially cause interference, short-circuits, or otherwise jeopardize the safety of flight and therefore must be switchable. Sometimes the switch is in the form a button, otherwise by a fuse. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several particular reasons that the transponder can be turned off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the transponder malfunctions, it may cause interruptions to all ATC surveillance in an area. There have been occurrences in the past that due to a fault the transponder it was basically acting as a radar jammer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In one particular incident it took a while before the aircraft that caused it was identified and after requesting the pilot to switch of the transponder, secondary surveillance was restored. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is that when the aircraft is at the gate, the transponder is switched of to reduce the amount of radio transmissions. 100 aircraft on the surface of a large airport can produce a massive Radio Frequency noise, which negatively affect radar systems. When taxiing, radar replies are useful for aircraft identification, hence the transponder is switched on at push-back or engine start. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For an example to see how such requirements are worded in aircraft certification regulations, see rbp's answer.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The focus here and in the media&lt;sup&gt;1&lt;/sup&gt; on the transponder in relation to hijacks is a red herring. If an aircraft is hijacked, there are way more important things to worry about than an active radar transponder.&lt;br&gt;&#xA;If hijackers turn off the transponder it means that they have access to the cockpit already. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;This answer was written shortly after flight &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot;&gt;MH370&lt;/a&gt; went missing while en-route from Kuala Lumpur to Beijing. Initial speculation focussed on a possible hijack scenario.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-06T21:47:45.117" LastActivityDate="2015-05-06T21:47:45.117" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2269" PostTypeId="1" AcceptedAnswerId="2274" CreationDate="2014-03-14T13:52:45.997" Score="29" ViewCount="10168" Body="&lt;p&gt;I use Flight Radar 24 on my iPad to track friends/families flights when they are traveling (not paranoia, just curious).  I've noticed that, quite often, their plane will jump from one location to another, or jump backwards down the flight path, or zoom forward, or any other number of motions that I assume the plane isn't actually making.  (My personal favorite being when they miss the runway on touchdown and the plane disappears.  If that actually happened as often as Flight Radar 24 made it look like it was happening...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes the planes do this on Flight Radar 24?  Why can't it just track the planes correctly?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="19" LastEditDate="2014-03-19T20:56:42.477" LastActivityDate="2018-07-15T17:22:26.577" Title="Why do aircraft on Flight Radar 24 jump around randomly sometimes?" Tags="&lt;air-traffic-control&gt;&lt;ads-b&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2270" PostTypeId="5" CreationDate="2014-03-14T13:55:49.330" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-14T13:55:49.330" LastActivityDate="2014-03-14T13:55:49.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2271" PostTypeId="4" CreationDate="2014-03-14T13:55:49.330" Score="0" Body="Malaysia Airlines Flight 370 disappeared on 8 March 2014 while en-route from Kuala Lumpur to Beijing with 239 persons on board.  " OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-03-14T15:12:15.693" LastActivityDate="2014-03-14T15:12:15.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2272" PostTypeId="2" ParentId="2216" CreationDate="2014-03-14T14:00:06.723" Score="1" Body="&lt;p&gt;Depends on what you mean by &quot;derive the equations&quot;. If you really mean that you want to work your way up to that formulation starting from the basics, well you start from good old Newton:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\overrightarrow{F}=m\overrightarrow{A}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the equivalent for moments ($\overrightarrow{}$ indicates vectors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point you need a reference system in which to decompose your vectorial equations (body-fixed, earth-fixed, stability axes: the choice influences which terms you'll be able to simplify later) and a description of your system: which forces are applied on the aircraft? how can I describe them as functions of the aircraft state?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point you substitute in your original equation and carry on the computation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can consult &lt;a href=&quot;https://www.princeton.edu/~stengel/MAE331Lectures.html&quot; rel=&quot;nofollow&quot;&gt;these lecture slides&lt;/a&gt; to see step-by-step how it can be done. Lecture 8 and 9 for the general 6DoF case and lecture 11 for your particular question.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-08-19T21:40:43.290" LastActivityDate="2015-08-19T21:40:43.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2274" PostTypeId="2" ParentId="2269" CreationDate="2014-03-14T14:17:09.140" Score="33" Body="&lt;p&gt;FR24 relies for most of the tracks on ADS-B data. Part of the ADS-B transmissions is the position. There are three causes of the behaviour that you observe:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1). Aircraft landing next to the runway&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The position source onboard the aircraft is not always GPS. Mainly older aircraft (e.g. Fokker 100) have their Inertial Navigation System (INS) coupled to the ADS-B transmitter. The INS relies not on external radio measurements but only on measured acceleration and rotation to track its position. It is usually correct at take-off, but it develops biases over time and therefore the landing appears quite often next to the runway. I can assure you that this is mostly misleading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2). Short time track offset&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most aircraft the ADS-B position is from GPS. When the GPS loses its  position fix, the system falls back to INS. As described above, the INS position is slowing drifting from the truth during the flight, so the ADS-B track will shortly jump aside to the INS position until the GPS comes back. When short (e.g. 1 position update) the offsets appear as spikes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mFnFY.jpg&quot; alt=&quot;INS jump&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3). Long distance jumps (180 NM, 360 NM) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the limited number of bits available in the ADS-B messages, position is encoded in a complex format called Compact Position Reporting. It requires at least two position messages to decode the first position of a track, from that point onward, every message will constitute a position update. When no proper verification algorithms are used in the software, it may occur that a receiver station initializes the track wrongly, usually causing a jump of 180 or 360 NM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note: When INS is used a the position source, the ADS-B data contains an indication that the data is not to be trusted, but that is silently ignored by FR24.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-03-18T22:03:08.457" LastActivityDate="2014-03-18T22:03:08.457" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2275" PostTypeId="1" AcceptedAnswerId="2276" CreationDate="2014-03-14T14:36:58.503" Score="19" ViewCount="32502" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/2274/609&quot;&gt;this question&lt;/a&gt;, the answer notes that some ADS-B systems are connected to Inertial Navigation Systems (INS), and says they are less accurate than GPS.  What exactly is an INS?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple sub questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why is it less accurate?   &lt;/li&gt;&#xA;&lt;li&gt;The other post mentions they tend to&#xA;develop biases as they get older, why is that? &lt;/li&gt;&#xA;&lt;li&gt;Are they being phased&#xA;out?  Or are they used as backup?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2018-06-16T12:09:32.100" Title="What is an Inertial Navigation System? How does it work?" Tags="&lt;navigation&gt;&lt;inertial-nav-system&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2276" PostTypeId="2" ParentId="2275" CreationDate="2014-03-14T15:05:23.867" Score="21" Body="&lt;p&gt;Inertial Navigation Systems, unlike other navigation systems, do not depend on external (radio) measurements. Instead an INS keeps track of its position by accurately measuring acceleration (accelerometers) and rotation (gyroscopes). It therefore works in remote areas where there are no ground based navaids available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initially, the INS gets its position from pilot input at the gate, or in more recent systems from GPS, sometimes even during flight. By measuring all the accelerations and rotations and integrating them into speed and direction the position is tracked. In doing this, the INS has to correct for the rotation of the earth and the related Coriolis force. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to small inaccuracies in the measurements the velocity error and, with that, the position errors grow over time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; has quite a detailed article about the history and working of the INS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While raw INS position has mainly been replaced by GPS measurements on oceanic flights, the system is not being phased out. GPS is a sensitive systems and by crosschecking it with INS, errors can be detected in both systems. It is often used as a backup to GPS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Integrated GPS / INS systems provide better systems integrity and allow the navigation system to coast through short GPS outages with high accuracies. In addition to that, the (laser) gyroscopes of the INS are often used to provide data to the digital artificial horizon displays in the cockpit and to the auto flight systems. In this case the term Inertial Reference Unit (IRU) is used, which acts as a basis for the INS.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2017-11-13T09:50:25.337" LastActivityDate="2017-11-13T09:50:25.337" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2277" PostTypeId="2" ParentId="2275" CreationDate="2014-03-14T15:05:34.860" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow&quot;&gt;Inertial Navigation System&lt;/a&gt; it uses a planes motion as detected by on-board accelerometers and gyroscopes to find where it is going using no external reference points.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A plane has a certain known heading and speed, when the planes makes a turn, hits a headwind,... accelerometers and gyroscopes will detect the change in motion and orientation and update accordingly. This means that initial accuracy depends on the how accurate the initial position speed and heading are when INS is initialized. The accelerometers and gyroscopes have limited granularity/accuracy and extrapolating your position from relative angle changes will compound an earlier error immensely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example if the System is off by 1 degree on a turn then after 500 miles it will be off by (500*&lt;a href=&quot;http://en.wikipedia.org/wiki/Chord_%28geometry%29&quot; rel=&quot;nofollow&quot;&gt;crd&lt;/a&gt;(1°)=500*2*sin(0.5°)=) 8.7 miles assuming all other information is correct. (this example is not fully correct as the gyros measure rate of turn rather than actual angle turned)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;INS is used primarily as a supplemental source of navigation data and as a fall back when other sources are unavailable. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-03-14T15:05:34.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2278" PostTypeId="1" CreationDate="2014-03-14T15:11:31.413" Score="9" ViewCount="5323" Body="&lt;p&gt;An aircraft's &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Communications Addressing and Reporting System&lt;/a&gt; uses line of sight HF via ground stations or satellites to communicate with its base station. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This system allows for three types of messages to be sent:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air Traffic Control&lt;/li&gt;&#xA;&lt;li&gt;Aeronautical Operational Control&lt;/li&gt;&#xA;&lt;li&gt;Airline Administrative Control&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aeronautical operational control and airline administrative control messages are used to communicate between the aircraft and its base. Various types of messages are possible, for example, relating to fuel consumption, engine performance data, aircraft position, in addition to free text.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can ACARS be turned off? Would this generate a warning at the base station?&lt;/li&gt;&#xA;&lt;li&gt;Can ACARS send postion, altitude and heading information automatically?&lt;/li&gt;&#xA;&lt;li&gt;Can ACARS be repeatedly &lt;em&gt;pinged&lt;/em&gt; to track an aircraft's position and heading? Would this require any intervention by the pilots? (&lt;a href=&quot;https://aviation.stackexchange.com/q/2319/193&quot;&gt;posted separately&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Is this system standard on commercial airliners?&lt;/li&gt;&#xA;&lt;li&gt;What data do Airlines collect from the ACARS, if any at all?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="193" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-03-15T13:55:47.610" Title="What data does ACARS send back to base? Can it be used to track a plane?" Tags="&lt;avionics&gt;&lt;acars&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2280" PostTypeId="2" ParentId="2278" CreationDate="2014-03-14T15:37:41.057" Score="0" Body="&lt;p&gt;ACARS does not include coordinates. It does include airspeed and altitude, as these are of interest for engine health. ACARS was functional on the Malaysian air flight, it was stated that before it went of radar, several messages were received.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good starting point on ACARS can be found on &lt;a href=&quot;http://www.skybrary.aero/index.php/Aircraft_Communications,_Addressing_and_Reporting_System&quot; rel=&quot;nofollow&quot;&gt;SKYbrary&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1470" LastEditorUserId="1470" LastEditDate="2014-03-14T17:08:42.313" LastActivityDate="2014-03-14T17:08:42.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2281" PostTypeId="2" ParentId="2278" CreationDate="2014-03-14T15:46:12.090" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Can ACARS be turned off? Would this generate a warning at the base station?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, ACARS can be turned off.  See &lt;a href=&quot;https://aviation.stackexchange.com/a/2162/69&quot;&gt;another answer of mine&lt;/a&gt; for more details.  Typically other systems use ACARS to send reports on a regular basis to update position and track other information, plus on an &quot;as-needed&quot; basis for abnormal things.  It would be up to the individual airline to look for these reports and to generate a warning if one didn't check in at the expected time, but I don't believe that they do this.  There is a lot of variation in the communication systems and they aren't 100% reliable so a lot of false alarms would be triggered.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Can ACARS send postion, altitude and heading information automatically?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ACARS itself can not, but other systems like the Flight Management Systems (FMS) or ADS-C on board the aircraft can use ACARS to send reports like this automatically, and in some cases they do.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again, ACARS is simply a communication system.  A message can be sent via ACARS which will forward to the appropriate system requesting this information and have it respond.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Is this system standard on commercial airliners?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I believe that most airliners that travel over international waters have ACARS, but I'm not sure if it's a requirement or not.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;What data do Airlines collect from the ACARS, if any at all?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This varies from airline to airline, but messages at the beginning and end of the flight (used to track flight time, etc.) and periodically during the flight are typical.  Usually periodic position updates and abnormal system indications are included as well.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-03-14T16:34:27.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2282" PostTypeId="2" ParentId="2278" CreationDate="2014-03-14T15:47:20.453" Score="3" Body="&lt;ul&gt;&#xA;&lt;li&gt;Can ACARS be turned off? Would this generate a warning at the base station?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Everything can be turned off, especially in an aircraft. It will probably not generate a warning at the base station immediately, because long distance data comms are not always reliable. It would cause too many false warnings. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can ACARS send position, altitude and heading information automatically?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Yes, ADS-C (Automatic Dependent Surveillance - Contract) provides such functionality over ACARS for ATC purposes. ATC have to establish the link first to get the reports automatically.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Using ADS-C position can be extracted by ATC, and the airline can do the same. Intervention by the pilots is not needed&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Was this system installed and functional on MAS370?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Installed yes, functional I don't know.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What data does Malaysian Airlines collect from the ACARS, if any at all?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I have no idea. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-03-14T15:47:20.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2283" PostTypeId="2" ParentId="2216" CreationDate="2014-03-14T15:54:27.687" Score="2" Body="&lt;p&gt;&lt;strong&gt;Note: Answer in progress!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Part 1&lt;/strong&gt; &#xA;&lt;em&gt;(Unfortunately I'm only familiar with #1 and #3 at the moment, not #2)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Footnote: This might be a bit simpler than your case, but hopefully it you'll be able to fill in the remaining gaps)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hlpy2.jpg&quot; alt=&quot;forces&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this, you can some the forces up according the direction of the velocity or the lift  vector. Doing this horizontally, you get equation 1, and likewise for vertical direction your equation 3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make this simpler to handle, we use small angle approximation consider $\cos(0)=1$ and $\sin(0)=0$. This simplifies down to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V:0=T-D$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L:0=mg-L$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(i.e. thrust equal to drag, lift equal to weight)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Part 2:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is basically the equations of a kinetic diagram of the Free Body Diagram above, where there can be a change either in airspeed of altitude. What your second equation says is that excess thrust (T-D, Thrust-Drag) can: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;be used to increase altitude: $m\times{g}\times\sin(y)$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and/ or &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;be used to increase airspeed: $m\times{v}$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-04-18T03:18:50.177" LastActivityDate="2014-04-18T03:18:50.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2284" PostTypeId="2" ParentId="2021" CreationDate="2014-03-14T16:21:50.747" Score="1" Body="&lt;p&gt;I am not myself a pilot, but I have a number of friends that pilot small private aircraft and use cellphones while in flight.  At altitudes of 10 or 12 thousand feet and speeds of 150 kph they work just fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;People say they might 'interfere' with the aircraft.  But if the electronics in aircraft are really so susceptible to interference, why are you allowed to use cell phones in the airport?&lt;/p&gt;&#xA;" OwnerUserId="1472" LastActivityDate="2014-03-14T16:21:50.747" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2285" PostTypeId="1" CreationDate="2014-03-14T17:11:13.467" Score="2" ViewCount="298" Body="&lt;p&gt;It has been suggested in the media and in some answers here that airlines vary in the information they track about the status of their flights. Is there a publicly available resource that lists what information different airlines have about the location and status of their flights? For example, could a British Airways flight over the Atlantic or the middle of the Pacific have &quot;vanished&quot; in the same way that the Malaysian flight over the Gulf of Thailand?&lt;/p&gt;&#xA;" OwnerUserId="1432" LastActivityDate="2015-07-15T23:01:29.997" Title="Is there a list of what information different airlines track about their flights?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2286" PostTypeId="2" ParentId="556" CreationDate="2014-03-14T20:32:47.280" Score="5" Body="&lt;p&gt;I read once a book about survival which I can't find now. Basically it was an investigation from a journalist about how different people dealt with situations where their life was at stake. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the situations was obviously a plane crash. The one thing that I took from that book is that in the case of an emergency, you simply act by reflexes; you don't have time to think. Therefore it is very important that you memorize the safety instructions at the beginning of the flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, those silly instructions that you ignore while checking Facebook can save your life. So &lt;strong&gt;know where your nearest exit is, how to use the oxygen mask and where the life vest is&lt;/strong&gt;. &lt;/p&gt;&#xA;" OwnerUserId="1473" LastEditorUserId="97" LastEditDate="2014-03-15T19:36:06.347" LastActivityDate="2014-03-15T19:36:06.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2287" PostTypeId="1" AcceptedAnswerId="2289" CreationDate="2014-03-14T20:57:36.540" Score="17" ViewCount="17387" Body="&lt;p&gt;How much the pitch (horizontal orientation) can differ from the angle of attack? I am trying to understand the claim that &quot;angle of attack indicator was unfortunately not available&quot;, contributing to problems during Air France &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;Flight 447&lt;/a&gt;. &lt;a href=&quot;http://en.wikipedia.org/wiki/Attitude_indicator&quot; rel=&quot;noreferrer&quot;&gt;Attitude indicator&lt;/a&gt; most likely was available?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="69" LastEditDate="2014-03-14T21:52:05.543" LastActivityDate="2020-01-15T16:42:10.097" Title="Can the pitch be very different from the angle of attack?" Tags="&lt;aerodynamics&gt;&lt;flight-instruments&gt;" AnswerCount="5" CommentCount="12" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2288" PostTypeId="2" ParentId="2287" CreationDate="2014-03-14T21:20:38.877" Score="11" Body="&lt;p&gt;It can be. Remember that the angle of attack is the angle between the chord line of the airfoil and the relative wind. Imagine if the plane is level with the horizon with zero airpseed. It will fall straight down, putting the angle of attack close to 90 degrees with the pitch close to zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, during normal flight it's not likely that pitch and angle of attack will be excessively different. But honestly the two aren't closely related: You can exceed the critical angle of attack and stall at any pitch, bank, or yaw angle.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-03-14T21:20:38.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2289" PostTypeId="2" ParentId="2287" CreationDate="2014-03-14T21:34:16.303" Score="12" Body="&lt;p&gt;The angle of attack is the angle between the wing (wing chord to be precise) and the direction of travel (undisturbed airflow). The angle of pitch is the angle between the main body axis and the horizon. The difference can theoretically be any angle, but during normal flight it will be limited to about 15 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason that the angle of attack sensor was inoperative was due to low airspeed. Below 60 knot IAS the indication is unreliable and therefore the indicator is inhibited. This also inhibits the stall warning. This lead to the confusing situation that lowering the nose to correct the stall increased the airspeed beyond 60 knots, thereby reactivating the stall warning.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-02-07T17:31:13.937" LastActivityDate="2015-02-07T17:31:13.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2291" PostTypeId="1" AcceptedAnswerId="2294" CreationDate="2014-03-14T23:08:01.223" Score="9" ViewCount="15638" Body="&lt;p&gt;Most ATC in the world rely primarily on secondary radar to know where planes are. This requires that the transponder on the plane works correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that maintenance and deployment of primary radar is no longer a primary concern for airspace regulation. It becomes at best a secondary backup system before they need to pull out the &lt;a href=&quot;https://aviation.stackexchange.com/a/494/609&quot;&gt;flight progress strips and airways charts&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where are the spots that is not covered by primary radar? I understand that some military ships have primary radar and can act as a mobile radar during operations.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2021-01-02T00:51:33.097" Title="Where is the airspace not covered by primary Radar?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;&lt;radar&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2292" PostTypeId="1" AcceptedAnswerId="2293" CreationDate="2014-03-14T23:39:03.963" Score="30" ViewCount="14275" Body="&lt;p&gt;All this confusion over flight 370 has me wondering if it would be possible to hack into an airplane and control the autopilot or other on-board systems in a way that the pilots couldn't regain control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know some basic searching reveals some articles such as &lt;a href=&quot;http://www.businessweek.com/articles/2013-04-12/hacking-an-airplane-with-only-an-android-phone&quot;&gt;this one&lt;/a&gt;. If the plane can't be hacked, could someone with the proper knowledge snip or disable the pilot's override?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I know 0 about aviation, but I am a programmer. So my guess would be that anything that doesn't have a physical disconnect would be vulnerable to being hacked without being able to override it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional Disclaimer: This is a question about curiousity / possibility, not a how-to.&lt;/p&gt;&#xA;" OwnerUserId="1481" LastEditorUserId="790" LastEditDate="2014-03-15T19:52:54.023" LastActivityDate="2020-01-10T16:47:42.543" Title="Can a Boeing 777 be hacked?" Tags="&lt;navigation&gt;&lt;aircraft-systems&gt;&lt;security&gt;&lt;boeing-777&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2293" PostTypeId="2" ParentId="2292" CreationDate="2014-03-14T23:54:36.693" Score="29" Body="&lt;p&gt;As of currently, the answer to this question is in principle &lt;strong&gt;no for commercial aircraft&lt;/strong&gt;, at least not remotely. There are two parts to this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a system perspective:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft systems could probably be 'hacked'- assuming you could for instance screw up the flight computer by changing the chips in the belly- but there is no way you could really pull this off without the pilots noticing the course being way off from the compass for instance, so they'd figure out and shut it off. Many systems are not connected in a way that allows them to be cause damage to others. Systems are also pretty dedicated- if it's supposed to fly the plane, that's what it does, if it's supposed to navigate, that's what it does.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Systems on aircraft generally a have limited, if any, connection to the outside world. There are a few systems that have the ability to connect to the ground, and this is generally limited to simple text messages. Most of the electronics on the 777 are from the type's introduction in 1994. A decent analogy I think is trying to hack an early cell phone remotely. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And from a practical standpoint:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft are generally very stiff when it comes to changes- they are often approved in a certain configuration, and that then sticks, so there's little need to change stuff, and hence it's not possible. This applies to the autopilot and flight controls- once it's there, it stays there.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As a few people have pointed out, these systems are proprietary and closed source, making it difficult to program them if you're an outsider, but in theory it might be possible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The fact that no aircraft, even the computer-intensive Airbus, have really been hacked to any extent, the notion that the entire aircraft would be taken over and flown somewhere is impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As for original question &lt;a href=&quot;http://www.businessweek.com/articles/2013-04-12/hacking-an-airplane-with-only-an-android-phone&quot; rel=&quot;noreferrer&quot;&gt;link&lt;/a&gt;:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“The FAA has determined that the hacking technique described during a&#xA;  recent computer security conference does not pose a flight safety&#xA;  concern because it does not work on certified flight hardware,” he&#xA;  said.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“The described technique cannot engage or control the aircraft’s&#xA;  autopilot system using the FMS or prevent a pilot from overriding the&#xA;  autopilot,” said Dorr.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“Therefore, a hacker cannot obtain ‘full control of an aircraft,’ as&#xA;  the technology consultant has claimed,” said Dorr.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On a similar accord, I think I heard a story about a Bombardier Dash 8 that got a computer virus once, but I think it never got beyond the navigation system, the most processing intensive part. Unfortunately, I can't find a source for this.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="938" LastEditDate="2016-08-20T04:27:36.500" LastActivityDate="2016-08-20T04:27:36.500" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2294" PostTypeId="2" ParentId="2291" CreationDate="2014-03-15T00:27:29.773" Score="8" Body="&lt;p&gt;There are a few spots not covered by primary radar. Here are a few I can think off:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Afghanistan, not really what you'd expect from flying between Europe and South East Asia. I was told though by the pilots that the Americans were keeping an eye on us. I'd imagine there are a few holes in the CIS countries as well.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Multiple areas in Africa, but this is improving I believe. There's a post on &lt;a href=&quot;https://www.pprune.org/african-aviation/509172-radar-coverage-west-africa.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;PPrune&lt;/a&gt;. Apparently known as the 'dark continent' for spotty coverage and consistency. South Africa has good coverage, and I'd guess the same for much of northern Africa as well.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A few remote areas in South America, then again, improving.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Oceans are not covered.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Determining factors are population density, aircraft density and economic development.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As more you Malaysia map, if there's a radar at Kota Bharu [KBR] airport, here's the map assuming a range of 200 Nm for the radar. It should in theory be well within reach.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EYToU.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EYToU.gif&quot; alt=&quot;map&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.gcmap.com/map?P=&amp;amp;R=200nm%40KBR&amp;amp;MS=wls&amp;amp;MR=60&amp;amp;MX=540x540&quot; rel=&quot;nofollow noreferrer&quot;&gt;gcmap.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;And an extended version:&lt;/p&gt;&#xA;&lt;p&gt;SGN Ho Chi Minh City (Saigon) [Tan Son Nhat Intl], VN&lt;/p&gt;&#xA;&lt;p&gt;KUA Kuantan [Sultan Abmad Shah Airport (Pedang Geroda Airport)], Pahang, MY&lt;/p&gt;&#xA;&lt;p&gt;KUL Kuala Lumpur (Sepang) [Intl], Selangor, MY&lt;/p&gt;&#xA;&lt;p&gt;KBR     Kota Bharu [Sultan Ismail Petra], Kelantan, MY&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7TNVi.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7TNVi.gif&quot; alt=&quot;map&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.gcmap.com/map?P=&amp;amp;R=200nm%40SGN%0a200nm%40KUA%0d%0a200nm%40KUL%0d%0a200nm%40KBR&amp;amp;MS=bm&amp;amp;MR=120&amp;amp;MX=540x540&amp;amp;PM=&quot; rel=&quot;nofollow noreferrer&quot;&gt;gcmap.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;Just for the interested, here's a map showing &lt;a href=&quot;https://web.archive.org/web/20200810181952/http://jsw.newpacificinstitute.org/?p=4011&quot; rel=&quot;nofollow noreferrer&quot;&gt;Japanese military radar&lt;/a&gt;, just to get an idea of coverage in a country full of people and planes.&#xA;&lt;a href=&quot;https://web.archive.org/web/20200208214807/https://i0.wp.com/newpacificinstitute.org/jsw/wp-content/uploads/2011/01/radarmapjapan.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://web.archive.org/web/20200208214807/https://i0.wp.com/newpacificinstitute.org/jsw/wp-content/uploads/2011/01/radarmapjapan.jpg&quot; alt=&quot;japanese&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Maps from &lt;a href=&quot;http://www.gcmap.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.gcmap.com/&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2021-01-02T00:51:33.097" LastActivityDate="2021-01-02T00:51:33.097" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2295" PostTypeId="5" CreationDate="2014-03-15T00:49:25.930" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-15T00:49:25.930" LastActivityDate="2014-03-15T00:49:25.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2296" PostTypeId="4" CreationDate="2014-03-15T00:49:25.930" Score="0" Body="For questions relating to military aviation or possible effects of a country's military on other forms of aviation." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-03-15T01:25:09.430" LastActivityDate="2014-03-15T01:25:09.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2297" PostTypeId="1" AcceptedAnswerId="2304" CreationDate="2014-03-15T01:45:55.887" Score="10" ViewCount="7350" Body="&lt;p&gt;If I hire a CFI to train me for the tailwheel endorsement (this question also applies to the high performance endorsement), can I log PIC time when flying the tailwheel aircraft, or do I have to log dual received?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is specifically about FAA rules related to training/logging time, but if there are different rules in different countries, feel free to answer about those too.&lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="69" LastEditDate="2014-03-15T03:21:21.733" LastActivityDate="2017-05-02T20:08:13.857" Title="Can I log PIC time when training for a tailwheel or high performance endorsement?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;far-61&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2298" PostTypeId="2" ParentId="2263" CreationDate="2014-03-15T01:48:49.150" Score="9" Body="&lt;p&gt;In many cases the decision to retire an airframe is economical rather than just &quot;it's old&quot;. Proper maintenance can extend an airplane's service life almost indefinitely but it gets more expensive with age/flying time/cycles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, new airplanes are cheaper to operate. If buying a new plane saves the purchase price in fuel in 5 years (quite possible) then you get one. It will not need any major maintenance in that period, further reducing the total cost of ownership. For example, a 707 and 737 are comparable in terms of capacity and range, but a brand-new 737 at \$90 million will cost a lot less over 5-10 years than a used 707 picked up for \$1 million.&lt;/p&gt;&#xA;" OwnerUserId="891" LastEditorUserId="72" LastEditDate="2014-04-23T12:42:59.163" LastActivityDate="2014-04-23T12:42:59.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2299" PostTypeId="2" ParentId="2292" CreationDate="2014-03-15T03:01:27.150" Score="10" Body="&lt;p&gt;There are certain communication systems that theoretically could be hacked into.  CPDLC is used to communicate digitally between pilots and controllers, so if it were to be hacked someone could send instructions to the pilot that would look like they were coming from a controller, and the pilots would not know the difference.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight plans can also be uploaded to the Flight Management System in some cases and could be used to program a different route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to keep in mind though is that the pilots are still intimately involved.  They see and approve all changes.  Minor changes might go unnoticed, but if they were instructed to fly in a completely different direction or to a different destination, they would probably start asking questions.  If they were sent directly towards a mountain or  another airplane, they would likely notice or other safety systems would step in to warn them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in a &quot;worst case&quot; scenario where someone were able to reprogram the autopilot (I don't believe that this is even possible right now) then the pilot can always just turn it off and fly manually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, this isn't really something to worry about.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-15T03:01:27.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2300" PostTypeId="2" ParentId="2291" CreationDate="2014-03-15T03:14:03.390" Score="0" Body="&lt;p&gt;There are large gaps in radar coverage in the Gulf of Mexico.  The FAA sponsored a study that looked into receiving ADS-B reports from aircraft in the surveillance gap and reformatting them to look like radar reports from a fake radar sensor in the Gulf so they could be ingested by their existing air traffic control software systems.  &lt;/p&gt;&#xA;" OwnerUserId="1484" LastActivityDate="2014-03-15T03:14:03.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2301" PostTypeId="1" CreationDate="2014-03-15T03:20:30.190" Score="15" ViewCount="2771" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Korean_Air_Flight_801&quot;&gt;Korean Air Flight 801&lt;/a&gt; crashed during bad visibility conditions in Guam because the ILS was out of commission and the pilot thought it wasn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question though is why he even tried to land there in the first place. Wouldn't an airport be closed during bad visibility conditions in that scenario? Or is it possible to land without ILS in bad weather conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I seem to remember someone talking about a step-chart or something like that as an alternative to ILS, is that what would be used in a case like that?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2019-10-21T02:01:40.643" Title="Is it legal to land in bad visibility conditions without ILS?" Tags="&lt;weather&gt;&lt;ils&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2302" PostTypeId="2" ParentId="2301" CreationDate="2014-03-15T03:28:21.603" Score="5" Body="&lt;p&gt;In the case of Flight 801 the pilot was using a &lt;a href=&quot;http://en.wikipedia.org/wiki/Distance_measuring_equipment&quot; rel=&quot;nofollow&quot;&gt;DME&lt;/a&gt; system.  This is basically a series of transponders that tell you how far away they are located, and you figure your position based on how far you are from the DME and how that correlates to their position on your charts.  You also have a step chart that tells you how far from the runway they are and what altitude you should be at when you get to the DMEs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happened with flight 801 is that the pilots were not aware that the Guam airport had it's final DME about 3 miles short off the threshold, instead of right at the end of the runway. They thought the last DME was just about where they were supposed to land (faulty training, it would seem).  When they got close to the ground and finally broke the clouds they realized their mistake and tried to do a go around, but the engines couldn't spool up in time...  They basically just landed 3 miles short of the runway.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-03-30T01:14:21.157" LastActivityDate="2016-03-30T01:14:21.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2303" PostTypeId="2" ParentId="2297" CreationDate="2014-03-15T03:30:46.993" Score="6" Body="&lt;p&gt;&lt;strong&gt;Yes, you can still log PIC time&lt;/strong&gt; &lt;em&gt;if you are appropriately rated for that aircraft&lt;/em&gt;, aside from the endorsement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if you are a Private Pilot, Airplane Single-Engine Land working on an endorsement in a Piper J-3 Cub, you would be able to log PIC time during your tailwheel training because the Cub is a single-engine land airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same goes for a MEL pilot adding tailwheel in a Twin Beech, which is an MEL airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you held &lt;em&gt;only an Airplane Single-Engine Sea&lt;/em&gt; certificate, you could not log PIC time until you added on an ASEL rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=8ba6845324e8b8199b52458202355632;rgn=div8;view=text;node=14:2.0.1.1.2.1.1.31;idno=14;cc=ecfr&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.51&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time. &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-&lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="39" LastEditorUserId="62" LastEditDate="2017-05-02T20:08:13.857" LastActivityDate="2017-05-02T20:08:13.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2304" PostTypeId="2" ParentId="2297" CreationDate="2014-03-15T03:31:22.100" Score="11" Body="&lt;p&gt;Yes and Yes; As long as you are rated for the category, class, and type (if required) of the aircraft that you are receiving the training in you could log both PIC and dual received.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 61.51(e)(i) covers the logging of PIC time (which is perfectly legal in the scenario that you describe if you are rated in the aircraft):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=8ba6845324e8b8199b52458202355632;rgn=div8;view=text;node=14:2.0.1.1.2.1.1.31;idno=14;cc=ecfr&quot;&gt;§61.51   Pilot logbooks.&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time. (1) A sport, recreational,&#xA;  private, commercial, or airline transport pilot may log pilot in&#xA;  command flight time for flights-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an&#xA;  aircraft for which the pilot is rated, or has sport pilot privileges&#xA;  for that category and class of aircraft, if the aircraft class rating&#xA;  is appropriate;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Training time is logged per 14 CFR 61.51(h) and you can log that too:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(h) Logging training time. (1) A person may log training time when&#xA;  that person receives training from an authorized instructor in an&#xA;  aircraft, flight simulator, or flight training device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That being said, you may &lt;strong&gt;not&lt;/strong&gt; act as the actual PIC however:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b87c39b886c45df379486076a7d0d057&amp;amp;node=14:2.0.1.1.2.1.1.21&amp;amp;rgn=div8&quot;&gt;§61.31   Type rating requirements, additional training, and&#xA;  authorization requirements.&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Additional training required for operating tailwheel airplanes.&#xA;  (1) Except as provided in paragraph (i)(2) of this section, no person&#xA;  may act as pilot in command of a tailwheel airplane unless that person&#xA;  has received and logged flight training from an authorized instructor&#xA;  in a tailwheel airplane and received an endorsement in the person's&#xA;  logbook from an authorized instructor who found the person proficient&#xA;  in the operation of a tailwheel airplane. The flight training must&#xA;  include at least the following maneuvers and procedures:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Notice that the regulations governing &lt;strong&gt;acting&lt;/strong&gt; as PIC are different than those governing &lt;strong&gt;logging&lt;/strong&gt; of PIC time.  This was done intentionally because there were so many pilots that were hired as SIC's at airlines with little to no PIC time and flew for years. When it was time for them to upgrade they didn't have enough PIC time even though they had lots of experience and could easily upgrade safely.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-15T03:37:16.243" LastActivityDate="2014-03-15T03:37:16.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2305" PostTypeId="2" ParentId="738" CreationDate="2014-03-15T03:42:53.283" Score="8" Body="&lt;p&gt;I had Flight Simulator X for years, and I just got back into it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like it for a hobby and I like to plan flights, I don't expect to be a real pilot and I don't expect to jump into a plane and fly it I'm not that crazy, but I notice that began to know the instruments and what they are used for, I love FSX and I'm proud of being a FSX Pilot. I know one thing for sure is that I have great respect for the pilots who do fly real airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another I like about FSX is that I can fly whatever aircraft I want to and don't have to pay or rent an airplane. I can't afford flight lessons so flying on the simulator is fun and can be very challenging especially when it comes to landing. For me I don't take it as a game but I take it as a learning tool, just in case I do decide to go to flight training, like I said earlier, I would not jump in a real airplane and try to fly it I would take flight lessons first, and hope that what I learn from the Flight Simulator would help me advance quicker.&lt;/p&gt;&#xA;" OwnerUserId="1486" LastEditorUserId="72" LastEditDate="2014-03-15T11:06:16.273" LastActivityDate="2014-03-15T11:06:16.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2306" PostTypeId="2" ParentId="2301" CreationDate="2014-03-15T03:45:25.680" Score="12" Body="&lt;p&gt;Airports don't typically close because of visibility.  In fact, ATC won't stop a pilot from flying an approach just because the weather is below minimums.  There are a couple of reasons for this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The determining factor for landing is &lt;strong&gt;flight visibility&lt;/strong&gt;, which may be different from the ground visibility that ATC has access to.  Under US Part 91 rules, a pilot may fly an approach even when the reported weather is below minimums, and if they have the required flight visibility and are in a position to land, they are allowed to land.  Part 121/135 operators aren't even allowed to try the approach though. ATC does not have to query the pilots to see which rules apply to them.  They assume that they won't ask for/accept a clearance if they aren't allowed to.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Different aircraft have different equipment and different pilots/operators have different training and rules.  For instance, one operator may be approved to use a Heads Up Display to land when the visibility is below landing minimums for another operator that does not have one.  ATC assumes that the pilot knows what they are doing and will only do what is legal for &lt;strong&gt;them&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;As far as this specific case, @JayCarr has done a good job of answering what heppened here.  The pilots simply flew the approach incorrectly....&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In regards to the &lt;strong&gt;title&lt;/strong&gt; of your question (which is a little bit different from the body of your question), each approach has the minimum flight visibility listed for it at the bottom of the approach plate.  Unless specific authorization is received to reduce the visibility (as in the HUD example above), no it is not legal to land if the visibility is below minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each approach procedure also lists minimum altitudes that you may fly to at various points during the approach.  If an ILS is out of service, there is very often another type of approach that may be flown that &lt;strong&gt;usually&lt;/strong&gt; prevents the pilot from descending as far.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very common type of approach plate will have an ILS approach combined with a Localizer approach.  Since an ILS is made up of a localizer for horizontal guidance and a glideslope for vertical guidance, if the glideslope becomes inoperative then the localizer can still be used on its own.  A localizer only approach without vertical guidance, uses &quot;step-down fixes&quot; to indicate when descents are allowed.  Basically, you determine when one of these fixes is crossed and you are now allowed to descend to the next minimum altitude.  From the side it looks kind of like a staircase with the last &quot;step&quot; being flown visually in order to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of the bottom portion of an ILS or LOC approach plate:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/r4oCv.png&quot; alt=&quot;Approach Plate Minimums&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-15T04:06:21.467" LastActivityDate="2014-03-15T04:06:21.467" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2308" PostTypeId="2" ParentId="2301" CreationDate="2014-03-15T03:59:06.860" Score="20" Body="&lt;p&gt;The answer is &quot;Maybe&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An ILS is actually comprised of two signals - a &lt;em&gt;localizer&lt;/em&gt; (which lines you up with the runway) and a &lt;em&gt;glideslope&lt;/em&gt; (which guides your vertical descent).&lt;br&gt;&#xA;If the glideslope is out of service (as it was when KAL801 was flying its approach) you fly a localizer-only approach, which requires visual contact with the runway at a higher altitude.&lt;br&gt;&#xA;In this case as shown on the plate below the ILS can be flown down to 531 feet (in red); the Localizer-Only approach can only be flown down to 1440 feet (in green).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dw71z.png&quot; alt=&quot;Approach Plate&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So as long as the crew had the minimum visibility and cloud height requirements (and observed the altitude restrictions on the approach) they could legally fly into the airport on a localizer-only approach&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the case of KAL801 &lt;a href=&quot;http://www.ntsb.gov/doclib/reports/2000/AAR0001.pdf&quot; rel=&quot;noreferrer&quot;&gt;there were a few contributing factors to the accident&lt;/a&gt; (go ahead and skip to page 142, unless you really like reading NTSB reports):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The glideslope may have been receiving false signals.&lt;br&gt;&#xA;The crew &lt;em&gt;should have disregarded the glideslope indication anyway&lt;/em&gt; as it was NOTAM'd out of service, but it's possible the crew followed the needle anyway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The DME fix for the approach is &lt;em&gt;not&lt;/em&gt; located at the airport.&lt;br&gt;&#xA;This may have caused the crew to believe they were closer to the airport than they actually were.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Because of (1), (2), or some other reason, the crew flew below the Localizer-Only minimum altitude.&lt;br&gt;&#xA;This is ultimately why they hit the hill -- they were too low during the approach.&lt;br&gt;&#xA;Had they been at or above the localizer-only minimum altitude they would have cleared the obstacles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-15T06:31:54.027" LastActivityDate="2014-03-15T06:31:54.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2309" PostTypeId="1" CreationDate="2014-03-15T04:08:33.730" Score="6" ViewCount="567" Body="&lt;p&gt;I have some questions about circle-to-land approaches. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we have the runway in sight above MDA, do we need to continue to descend to MDA on downwind? Can we just keep fly like a traffic pattern until abeam aiming point and then start the descent?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, If during circle to land approach we lose the runway on downwind but we are above MDA, do we need go missed still toward to the runway? Since we are above MDA we should still have obstacle clearance....&lt;/p&gt;&#xA;" OwnerUserId="1488" LastEditorUserId="572" LastEditDate="2015-02-19T09:52:58.623" LastActivityDate="2015-02-19T09:52:58.623" Title="Do I need to descend towards the Minimum Descent Altitude if I have the airport in sight?" Tags="&lt;faa-regulations&gt;&lt;instrument-procedures&gt;&lt;circling-approach&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2310" PostTypeId="2" ParentId="2309" CreationDate="2014-03-15T04:14:24.827" Score="4" Body="&lt;p&gt;No, you do not need to descend all of the way to the MDA if you have the required visibility to continue. In fact, I would recommend against it since it puts you awfully close to the ground while you are maneuvering to align with the runway.  Why do that if you don't have to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MDA stands for &lt;strong&gt;Minimum&lt;/strong&gt; Descent Altitude, and is just that.  The minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as going missed, you would fly the missed approach in the same way because while you may have obstacle clearance where you are now, the missed approach procedure assumes that you fly it the correct way, and in this case you just have some extra padding since you started out higher.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-15T04:14:24.827" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2313" PostTypeId="2" ParentId="2186" CreationDate="2014-03-15T09:26:22.360" Score="2" Body="&lt;p&gt;The technical answers have been great, but there is one very simple answer to why airlines don't provide parachutes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It implies that commercial flight isn't safe&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the similar reason that car's don't protect you to the nth degree, many people will stop using them as they'll realise just what they are actually doing, and as pointed out in another answer the margins are so low that a 10% drop in passengers would be ruinous to many airlines.&lt;/p&gt;&#xA;" OwnerUserId="1493" LastActivityDate="2014-03-15T09:26:22.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2314" PostTypeId="2" ParentId="2291" CreationDate="2014-03-15T11:57:28.807" Score="4" Body="&lt;p&gt;A lot of airspace is not covered with primary radar, at least not for ATC purposes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airspace above seas and oceans are not covered by ATC primary radars. ATC relies mainly on secondary radar for surveillance, primary radar is used mainly for airspace infringement protection and airport surface surveillance. Over oceans and remote areas procedural control is used, without any surveillance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most primary radars used for long range surveillance in ATC are operating in the L-Band. L-Band signals do not follow the curvature of the earth very well; at low altitude the range is limited because the aircraft are below the horizon. At higher altitudes the range is up to about 250NM, but only when the radar is operated at very high power, which is costly both in design and electricity bill. In many cases it is not needed to operate at long range.&#xA;Radar is also shielded by terrain; in mountainous areas it is difficult to cover the valleys. In Europe, and I believe also in the US, high altitudes are well covered by primary radar, at low altitude there are many gaps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lower band (HF - UHF) radar can be used to look over the horizon (OTH radar). This type of radars is used for Air Defence purposes. The resolution is very poor compared to radars used for ATC but it serves well as an early warning system for incoming enemy aircraft and missiles. This type of radar requires huge antenna arrays, over a kilometre long and they consume enormous amounts of power. &lt;img src=&quot;https://i.stack.imgur.com/eBQ9U.gif&quot; alt=&quot;JORN receiver site, Laverton&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effective range is typically about 3000 km. For example Australia has the &lt;a href=&quot;http://en.wikipedia.org/wiki/Jindalee_Operational_Radar_Network&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jindalee Operation Radar Network&lt;/a&gt;, that can see past Jakarta, Indonesia.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/rGOuf.png&quot; alt=&quot;JORN area of operation&quot;&gt;&#xA;&lt;em&gt;JORN coverage&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the missing Malaysian MH370, and the latest suspicions that the aircraft ended up West of Perth, I wonder whether the flight was tracked by the OTH Air Defence radars of Australia.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-03-15T17:57:20.020" LastActivityDate="2014-03-15T17:57:20.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2317" PostTypeId="1" CreationDate="2014-03-15T13:07:32.510" Score="32" ViewCount="57705" Body="&lt;p&gt;The alpha vane (also called AoA vane) is an external probe used to measure the angle of attack. I have been trying to understand how exactly it works, but I can't find any clear explanation or simulation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k0NTBm.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the vane static or dynamic i.e. does it rotate along its central axis?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that it has a significant surface area, I think that it would either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rotate because of the force/drag exerted by the airflow, and give an angle of attack proportional or equal to its angle of rotation&lt;/li&gt;&#xA;&lt;li&gt;Measure the force being exerted on it via a force sensor embedded in the surface&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is either of these correct?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In short, how does an alpha vane work?&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="15311" LastEditDate="2018-06-14T20:44:58.407" LastActivityDate="2019-03-11T09:32:56.017" Title="How does an alpha (AoA) vane work?" Tags="&lt;aircraft-systems&gt;&lt;avionics&gt;&lt;flight-instruments&gt;&lt;angle-of-attack&gt;&lt;sensors&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2318" PostTypeId="2" ParentId="2317" CreationDate="2014-03-15T13:10:57.693" Score="24" Body="&lt;p&gt;From what I have studied at my instrumentation course, it rotates and reads the angle between the current position and the reference position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You then have several (3-4) of them around the fuselage because a roll maneuver (for example) will alter the measurements asymmetrically and in this way you can compensate for this effect.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="753" LastEditDate="2019-02-06T12:12:57.860" LastActivityDate="2019-02-06T12:12:57.860" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="2319" PostTypeId="1" AcceptedAnswerId="2333" CreationDate="2014-03-15T13:55:07.713" Score="7" ViewCount="887" Body="&lt;p&gt;This is a followup to &lt;a href=&quot;https://aviation.stackexchange.com/q/2278/193&quot;&gt;What data does ACARS send back to base? Can it be used to track a plane?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had asked this as a part of the earlier question, but it seems to be a large enough issue to be separate (plus no answers covered this aspect). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All electronic communication systems have low level diagnostic and channel check packages (commands). By pinging, I mean to send a system specific query message, and estimate the response time at base station or first receiver. Repeat the procedure multiple times, and calculate the response time differences. (Assumption) If the response time is decreasing, then the aircraft is moving towards the receiver, if it is increasing, then the aircraft would be moving away. Couple the time difference obtained from multiple responses, with the location of the receivers (which may be satellites or ground stations). Then, approximate the plane heading, location or speed, with reference to the receiver, and then with reference to the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would a process like this be possible with a high speed aircraft's ACARS? Are there any aspects specific to an aircraft that would make this impractical?&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-03-22T08:02:41.343" Title="Is it possible to ping ACARS repeatedly and track an aircraft?" Tags="&lt;avionics&gt;&lt;acars&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2322" PostTypeId="2" ParentId="556" CreationDate="2014-03-15T16:04:17.503" Score="7" Body="&lt;p&gt;I am aware about the railway disaster where a passenger train hit a fuel cistern (1975, Žąsliai, Lithuania).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this disaster, it was the synthetic clothing that burned and melted easily that significantly reduced chances of successfully escaping from the burning coaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This experience probably is applicable for some aircraft disasters as well. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="97" LastEditDate="2014-03-15T19:32:54.767" LastActivityDate="2014-03-15T19:32:54.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2323" PostTypeId="2" ParentId="2319" CreationDate="2014-03-15T16:40:10.937" Score="2" Body="&lt;p&gt;In theory you can triangulate from any signal that is being sent from a craft, but the big problem you'll run into with this solution is that ACARS only fires off bursts every half of an hour or if the engine trips certain parameter flags.  Again, a possibility but not horribly useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose aircraft designers could go ahead and increase the number of pings with ACARS, but that doesn't really make a lot of sense when all aircraft are fitted with a couple of transponders and several other modes of communication (like calling the pilots via radio, for instances.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, I think the proper solution is to build a better GPS location system for aircraft.  One that pings a central system with the aircraft location repeatedly.  A purpose built system is going to be a lot better than piggybacking ACARS...&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-03-15T16:40:10.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2324" PostTypeId="2" ParentId="2292" CreationDate="2014-03-15T17:20:21.603" Score="0" Body="&lt;p&gt;&lt;em&gt;Any&lt;/em&gt; computer can be hacked. I'm not saying I have the knowledge to do it, or even know much about airplanes to tell you how. However if someone with the knowledge required had the proper time, motivation, and access to an aircraft, it could most definitely be done. If you're asking if a plane can be taken over from the ground midflight, without any prior modification, I can't answer that because I don't know enough about the system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically discussing &lt;em&gt;how&lt;/em&gt; to hack a plane midflight, with or without prior modifications, would probably get me flagged and placed on a list somewhere, so I decline to go into detail on that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, one must think about what wireless protocols are used for a plane to talk to the ground, what computer subsystems can access that physical link, and if those subsystems can control the plane, or access other subsystems that can control the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;'Locking a pilot out' probably involves disabling a manual switch somewhere, tricky to do via computer, but can be done given enough amperage was passed through the switch to blow it, or if it were rigged before hand (prior modification).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we're talking how to, this is a &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B000P1FZEA&quot; rel=&quot;nofollow&quot;&gt;episode of Numb3rs&lt;/a&gt; with a similar theme, however it wouldn't be far off from what would need to take place in real life.&lt;/p&gt;&#xA;" OwnerUserId="1505" LastActivityDate="2014-03-15T17:20:21.603" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2328" PostTypeId="1" AcceptedAnswerId="2329" CreationDate="2014-03-15T18:51:38.603" Score="26" ViewCount="22345" Body="&lt;p&gt;Could a pilot of an airliner incapacitate everyone outside the cockpit by somehow triggering a loss of cabin pressure while simultaneously disarming the airplane's oxygen masks, manipulating the air circulation system to induce hypoxia, or some other means?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, would it be a credible theory that the pilot de-pressurized the 777 flying &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot;&gt;Malaysia Airlines Flight 370&lt;/a&gt; and flew it off somewhere? &lt;/p&gt;&#xA;" OwnerUserId="972" LastEditorUserId="22550" LastEditDate="2018-12-11T14:12:20.827" LastActivityDate="2019-01-17T16:37:41.303" Title="Could a pilot incapacitate other crew/passengers by manipulating cabin air quality/pressure?" Tags="&lt;aircraft-design&gt;&lt;cabin-pressure&gt;&lt;boeing-777&gt;&lt;mh370-incident&gt;&lt;hypoxia&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2329" PostTypeId="2" ParentId="2328" CreationDate="2014-03-15T19:15:54.320" Score="21" Body="&lt;p&gt;The answer depends on what kind of aircraft you're talking about, and how much control the crew has over the pressurization systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in theory you &lt;strong&gt;could very well reduce or completely shut off the air to the cabin on a 777&lt;/strong&gt;. This could also be done by a single crew member alone. The pilots have full control of this system should say the one of the engines produce bad air to that cabin and would needed to be switched off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the oxygen masks- these are for emergency descent use and have a generator that runs out after about 15 minutes. The crew bottles last a bit longer I think, but these will also have a limit, and doing any attempt to break through the bullet-proof cockpit door in those conditions I'd imagine would be very difficult, since I'm not sure you're still picking up the amount of oxygen you normally would.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a similar situation (though not a deliberate attempt) you can read up on &lt;a href=&quot;http://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;noreferrer&quot;&gt;Helios Airways Flight 522&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an idea of how the pilot masks look, see &lt;a href=&quot;http://www.youtube.com/watch?v=k1jIjMIikF4&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=B777-Air_Systems.pdf&quot; rel=&quot;noreferrer&quot;&gt;SmartCockpit&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="9544" LastEditDate="2018-12-11T15:55:06.450" LastActivityDate="2018-12-11T15:55:06.450" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="2330" PostTypeId="5" CreationDate="2014-03-15T20:14:21.300" Score="0" Body="&lt;p&gt;The &lt;em&gt;Boeing 777&lt;/em&gt; (pronounced either “seven seventy-seven” or “triple seven”) is a long-range twin-engine widebody jetliner produced by &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt; since 1993; it is the largest twinjet in the world, Boeing’s second-largest airliner, behind only the &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt; (and the newer, bigger 777s are quickly closing that gap), Boeing’s most profitable jetliner, and the company’s most-produced widebody jetliner (although, with 1,582 built through the end of 2018, it is still far behind the 10,000-plus airframes of the company’s most-produced jetliner &lt;em&gt;overall&lt;/em&gt; - the &lt;a href=&quot;/questions/tagged/boeing-737&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-737&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-737&lt;/a&gt;, produced continuously since 1967 and the most-sold jetliner by anyone ever).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before the current design took shape, the 777 designation had been applied to a completely different aircraft - a widebody trijet (similar to the &lt;a href=&quot;/questions/tagged/dc-10&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-10&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-10&lt;/a&gt;) developed in the late 1970s, alongside the &lt;a href=&quot;/questions/tagged/boeing-757&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-757&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-757&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/boeing-767&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-767&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-767&lt;/a&gt;.  The advent of &lt;a href=&quot;/questions/tagged/etops&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;etops&amp;#39;&quot; rel=&quot;tag&quot;&gt;etops&lt;/a&gt; allowed twinjets, such as the 767, to fly the lucrative &lt;a href=&quot;/questions/tagged/transatlantic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;transatlantic&amp;#39;&quot; rel=&quot;tag&quot;&gt;transatlantic&lt;/a&gt; routes that had formerly required a trijet or quadjet, and, as a twinjet will always be cheaper and more efficient than an otherwise-similar trijet or quadjet, the trijet 777 never made it into production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This left a gap in Boeing’s catalog between the 767 (on the lower end) and the 747 (on the upper end), which the airlines - at the time - filled with the DC-10 and &lt;a href=&quot;/questions/tagged/lockheed-tristar&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lockheed-tristar&amp;#39;&quot; rel=&quot;tag&quot;&gt;lockheed-tristar&lt;/a&gt;; however, as retirement age for these older trijets inexorably crept closer, Boeing began work on a larger 767 to compete with the jetliners in Airbus’s and McDonnell Douglas’s pipelines (the &lt;a href=&quot;/questions/tagged/airbus-a330&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a330&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a330&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/md-11&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;md-11&amp;#39;&quot; rel=&quot;tag&quot;&gt;md-11&lt;/a&gt;, respectively).  They soon realized that the airlines, far from wanting merely another 767 stretch, were looking for something completely new, larger, more flexible, cheaper, and, above all, &lt;em&gt;new&lt;/em&gt;.  They then brought said airlines onboard in the design process (an industry first), the better to serve Boeing’s prospective customers.  Although trying to make a one-size-fits-all product to satisfy all the demands of several different buyers can easily result in a product that is very late to market, and, when it does, finally, arrive, proves to be a mediocre compromise satisfying nobody, Boeing managed to avoid this trap with the 777, and instead produce an aircraft that came to market on time and satisfied &lt;em&gt;everybody&lt;/em&gt; (or, at least, everybody who had put in suggestions for what it should be able to do).  The 777 represented some other firsts for the company, as well; it was their first &lt;a href=&quot;/questions/tagged/fly-by-wire&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fly-by-wire&amp;#39;&quot; rel=&quot;tag&quot;&gt;fly-by-wire&lt;/a&gt; aircraft (a technology pioneered in the airliner market just the previous decade by the &lt;a href=&quot;/questions/tagged/airbus-a320&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a320&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a320&lt;/a&gt;), as well as the first  airliner designed by &lt;em&gt;anyone&lt;/em&gt; entirely by computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 777 first flew on 12 June 1994; an extensive &lt;a href=&quot;/questions/tagged/flight-testing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-testing&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-testing&lt;/a&gt; program allowed it to be certified in both the U.S. and Europe in April 1995, receive U.S. approval for 180-minute ETOPS the following month (the first jetliner to have this approval from the moment it entered service), and carry its first paying passengers the month after &lt;em&gt;that&lt;/em&gt;, for United Airlines on 7 June 1995.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 777 mainly competes with the A330, &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/airbus-a350&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a350&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a350&lt;/a&gt;, as well as, to some extent (especially with the later, larger models), the 747; it also competed with the MD-11 when that type was still in passenger service, and still competes with it in the freighter market, as well as with older DC-10s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been nine commercial variants of the 777 over the years (eight passenger, one freighter), grouped into three main series:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777 Classics&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These models have a 60.93-meter (199-foot-11) wingspan, and are powered by one of these three &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt;s: the Pratt &amp;amp; Whitney PW4000, the Rolls-Royce Trent 800, or the General Electric GE90.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 777-200 (the last Boeing airliner to have a -100 variant was the 747) was the launch version of the 777, entering service, as previously stated, with United Airlines in June 1995.  Aimed at the U.S. domestic market, it has a 9,700-km (5,240-nmi) range, and typically carries about 300 passengers, although it can legally carry up to 440 in an all-economy sardine configuration.  88 were delivered, and 55 remain in operation.&lt;/li&gt;&#xA;&lt;li&gt;The 777-200ER (&lt;strong&gt;E&lt;/strong&gt;xtended &lt;strong&gt;R&lt;/strong&gt;ange) flew its first passengers in February 1997, with British Airways.  The Extended Range (up to 13,000 km [7,000 nmi]), intended to make it more competitive for transatlantic flights, comes from its uprated engines, whose greater thrust allow it a heavier maximum takeoff weight, enabling it to carry more fuel (although not more passengers) than the original 777-200.  It proved far more popular than the earlier model, selling 422 aircraft, with 338 of these still flying today; it is also, possibly not coincidentally, the only Classic-series 777 still offered by Boeing (although there are currently no orders outstanding for it).&lt;/li&gt;&#xA;&lt;li&gt;The 777-300, a stretch of the 777-200, entered service in May 1998 with Cathay Pacific.  Its 10.1-meter (33-foot)-longer fuselage lets it carry around 370 passengers in a typical configuration, and up to 550 in full-on sardine mode; it also made it, at the time, the longest jetliner ever built.  The longer, heavier fuselage is somewhat compensated for by its use of the higher-capacity fuel tanks and more powerful engines introduced on the 777-200ER, and it can fly up to 11,100 km (6,000 nmi) in a single leap with a full passenger load.  48 remain in service out of a total 60 delivered; the last of these was in 2006, following the introduction of…&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;...the Ultra-Long-Range variants&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These models have a 64.80-meter (212-foot-7) wingspan, with the wingtips raked back to reduce drag, and are powered solely by the GE90-110/115 engine, the most powerful and (until 2018) largest turbofan ever built.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The first was the 777-300ER (derived from the 777-300), introduced with Air France in the spring of 2004.  Compared to the 777-300, its even more powerful engines let it carry yet more fuel, giving it a range of up to 13,650 km (7,370 nmi) with the same passenger capacity as the earlier model.  It is the most popular 777 yet, with 799 delivered (784 remaining in service) and 45 more on order.&lt;/li&gt;&#xA;&lt;li&gt;The 777-200LR (an even &lt;strong&gt;L&lt;/strong&gt;onger &lt;strong&gt;R&lt;/strong&gt;ange development of the 777-200ER) entered service with Pakistan International Airlines in early 2006, and is the longest-range of the second-generation models, being capable of up to 15,840 km (8,550 nmi) at a time.  As with the 777-300ER, its more powerful engines let it carry more fuel than its predecessor.  59 have been built, and 50 still fly.&lt;/li&gt;&#xA;&lt;li&gt;The 777F, the first dedicated freighter version of the 777, reached its first customer (Air France) in February 2009; it is based on the 777-200LR, although Boeing has also considered a freighter version of the 777-300ER, as well as freighter conversions of passenger 777-200ERs and 777-300ERs.  Compared to the 777-200LR, it sacrifices range for cargo capacity, but can still fly 9,200 km (4,970 nmi) with a full load, and farther with a less-than-full load.  140 are currently in service out of a total of 154 deliveries, plus 59 outstanding orders.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777X series&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These models have a 71.8-meter (235-foot-5) wingspan, with raked-back wingtips like those found on the second-generation (ultra-long-range) models; to allow them to fit into gates and taxiways designed for the earlier 777s, the 777Xs use &lt;a href=&quot;/questions/tagged/folding-wings&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;folding-wings&amp;#39;&quot; rel=&quot;tag&quot;&gt;folding-wings&lt;/a&gt;, with the outermost 3.5 meters (11 feet) of each wing folding up to vertical when the aircraft is taxiing or parked.  Despite their greater span, the wings of the 777X models are actually lighter than those of earlier 777s, due to being built from &lt;a href=&quot;/questions/tagged/composite-materials&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;composite-materials&amp;#39;&quot; rel=&quot;tag&quot;&gt;composite-materials&lt;/a&gt; rather than the traditional aluminium.  They use the General Electric GE9X, an even larger (though slightly less powerful) derivative of the GE90 with a considerably higher &lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt;, and, hence, greater &lt;a href=&quot;/questions/tagged/efficiency&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;efficiency&amp;#39;&quot; rel=&quot;tag&quot;&gt;efficiency&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 777-9, which first flew on 25 January 2020 (delayed from 2019 due to issues with the GE9X engine), becoming the first of the 777X models to take to the air, is scheduled to enter service in 2021; able to carry 414 passengers 14,000 km (7,600 nmi) nonstop in a typical configuration, it can sardine in over 600 warm bodies in an all-economy configuration (rivalling the 747), although at the price of reduced range.  Boeing has accumulated 273 orders for the type.&lt;/li&gt;&#xA;&lt;li&gt;The 777-8, when it flies (scheduled for 2021), will be the longest-range 777 yet, able to fly 16,110 km (8,700 nmi) nonstop with a ~370-passenger three-class capacity and a 550-passenger sardine capacity (similar to the 777-300 and 777-300ER).  53 have been ordered by various airlines.&lt;/li&gt;&#xA;&lt;li&gt;The largest-ever 777, the 777-10, is a stretch of the 777-9, and will be able to carry even more passengers (precisely &lt;em&gt;how&lt;/em&gt; many has not yet been finalized, although it has been reported that its capacity would be great enough for it to compete directly with the &lt;a href=&quot;/questions/tagged/airbus-a380&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a380&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a380&lt;/a&gt;, which can carry over 700 passengers in an all-economy configuration).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information, see Wikipedia’s articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 777 in general, and the Classics and ULRs in particular&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777X&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 777X&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="22726" LastEditDate="2020-01-30T01:08:42.440" LastActivityDate="2020-01-30T01:08:42.440" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2331" PostTypeId="4" CreationDate="2014-03-15T20:14:21.300" Score="0" Body="A long-range wide-body twinjet airliner produced by Boeing since 1993, with over 1,500 built." OwnerUserId="790" LastEditorUserId="14897" LastEditDate="2019-02-23T14:17:39.613" LastActivityDate="2019-02-23T14:17:39.613" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2332" PostTypeId="2" ParentId="2292" CreationDate="2014-03-15T20:35:18.357" Score="9" Body="&lt;p&gt;Everything is possible. For example, NSA could have forced a manufacturer to include some backdoor in the system for their use.&lt;/p&gt;&#xA;" OwnerUserId="1513" LastActivityDate="2014-03-15T20:35:18.357" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2333" PostTypeId="2" ParentId="2319" CreationDate="2014-03-15T20:59:20.787" Score="5" Body="&lt;p&gt;When ACARS communicates via INMARSAT satellite (other options are VHF or HF to ground stations), the satellite can ping the receiver on the aircraft and determine the distance from the delay of the reply. The satellite is geostationary, meaning that it is a fixed point 35786 km above the earth. Based on the distance from the satellite you can calculate a circle where the aircraft must be on. This has been done for MH370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZphW4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZphW4.jpg&quot; alt=&quot;MH370 Inmarsat range rings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the geostationary orbit is so high, a single satellite covers a large portion of the earth. Only a single satellite covered the MH370 flight. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-03-15T23:25:17.157" LastActivityDate="2014-03-15T23:25:17.157" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2335" PostTypeId="1" CreationDate="2014-03-15T22:23:41.997" Score="2" ViewCount="162" Body="&lt;p&gt;In the 911 terror attack the transponders were turned off.  Who is to blame for the lack of foresight that has allowed another jet liner to shut off their transponders.  This is a ¼ billion-dollar ship; it seems impossible that engineers would not be able to design a safe and reliable back up transponder system that would not jam other signals, and would not be a fire hazard.&lt;/p&gt;&#xA;" OwnerUserId="1503" LastEditorUserId="64" LastEditDate="2014-03-15T22:31:33.060" LastActivityDate="2014-03-15T22:31:33.060" Title="Why after 911; do we not have &quot;fail-safe&quot; transponders that cannot be turned off?" Tags="&lt;safety&gt;&lt;security&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2014-03-15T22:31:07.403" ContentLicense="CC BY-SA 3.0" />
  <row Id="2336" PostTypeId="1" CreationDate="2014-03-16T02:03:55.437" Score="9" ViewCount="5230" Body="&lt;p&gt;I recently attempted to take my Commercial/ME/Instrument checkride. I passed the oral exam portion, but shortly after the engine started running rough. After making it through about 3-4 maneuvers and tasks, the DPE and myself called safety of flight and brought the plane back in. He did a discontinuance on my app for a new rating, but did check me off on the tasks performed. He stated that the tasks performed have a two month shelf life. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question is, does the oral exam have the same shelf life since I passed it?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason this is a concern is that I have a deployment with the Guard in about two weeks. If the plane doesn't get back up and running, I'm hosed. My shelf life on the checkride stuff expires on 5/31 and I won't be back home from my deployment until early to mid-June.&lt;/p&gt;&#xA;" OwnerUserId="1519" LastEditorUserId="39" LastEditDate="2014-03-16T05:18:58.873" LastActivityDate="2014-03-16T05:18:58.873" Title="Once you have passed the oral portion of a checkride, do you have to retake it ever again?" Tags="&lt;faa-regulations&gt;&lt;checkride&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2337" PostTypeId="2" ParentId="2336" CreationDate="2014-03-16T02:06:11.987" Score="7" Body="&lt;p&gt;Unfortunately, yes.  It is part of the checkride and if you don't finish it within the required time you will need to take the entire checkride again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-12C.pdf&quot;&gt;commercial PTS&lt;/a&gt; shows the areas of operations that are included in the checkride, and the oral itself is given throughout the entire process.  What most people consider &quot;the oral&quot; is the examiner asking questions during the &quot;preflight preparation&quot; portion of the checkride.  This is where they ask the most questions because in all reality, this is where you as a pilot should be asking the most questions.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a note in the beginning of the PTS which talks about this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Examiner Responsibility&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The examiner conducting the practical test is responsible for &#xA;  determining that the applicant meets the acceptable standards of &#xA;  knowledge and skill of each Task within the appropriate practical &#xA;  test standard. Since there is no formal division between the “oral” &#xA;  and “skill” portions of the practical test, this becomes an ongoing &#xA;  process throughout the test. Oral questioning, to determine the &#xA;  applicant’s knowledge of Tasks and related safety factors, should be &#xA;  used judiciously at all times, especially during the flight portion of&#xA;  the  practical test. Examiners shall test to the greatest extent&#xA;  practicable  the applicant’s correlative abilities rather than mere&#xA;  rote  enumeration of facts throughout the practical test. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a small aside, you don't really get two months, but rather 60 days.  This is covered in 14 CFR 61.43:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=76655077ab7c5ad615f8bb0878093f2d&amp;amp;node=14:2.0.1.1.2.1.1.27&amp;amp;rgn=div8&quot;&gt;&lt;strong&gt;§61.43 Practical tests: General procedures.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) If a practical test is discontinued, the applicant is entitled&#xA;  credit for those areas of operation that were passed, but only if the&#xA;  applicant:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Passes the remainder of the practical test within the 60-day&#xA;  period after the date the practical test was discontinued;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Presents to the examiner for the retest the original notice of&#xA;  disapproval form or the letter of discontinuance form, as appropriate;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Satisfactorily accomplishes any additional training needed and&#xA;  obtains the appropriate instructor endorsements, if additional&#xA;  training is required; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Presents to the examiner for the retest a properly completed and&#xA;  signed application.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-16T02:17:40.673" LastActivityDate="2014-03-16T02:17:40.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2338" PostTypeId="2" ParentId="492" CreationDate="2014-03-16T04:18:53.543" Score="4" Body="&lt;p&gt;ATC aircraft separation is built upon the assumption of no radar by way position reports. At compulsory reporting points (&lt;a href=&quot;http://skyvector.com/?ll=21.616579334768954,-152.9948730465923&amp;amp;chart=304&amp;amp;zoom=3&quot; rel=&quot;nofollow&quot;&gt;black triangle&lt;/a&gt; on enroute charts), an IFR aircraft (unless radar identified) is required to report (see &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0503.html&quot; rel=&quot;nofollow&quot;&gt;5-3-2 of the AIM&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Identification;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Position;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Time;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Altitude or flight level (include actual altitude or flight level&#xA;  when operating on a clearance specifying VFR-on-top);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Type of flight plan (not required in IFR position reports made&#xA;  directly to ARTCCs or approach control);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) ETA and name of next reporting point;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) The name only of the next succeeding reporting point along the&#xA;  route of flight; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) Pertinent remarks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ATC uses the position and ETA to keep aircraft separated. Most of the US is covered by radar, but remote parts of Alaska and oceanic still use position reports. If ATC radar is not functioning (rare), then the system reverts to position reports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving forward, ADS-B allows aircraft to self broadcast its position. A network of ground and satellite ADS-B receivers can build up a picture of the traffic.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2014-03-16T04:18:53.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2340" PostTypeId="2" ParentId="2285" CreationDate="2014-03-16T06:47:13.233" Score="2" Body="&lt;p&gt;There is no particular list that provided by airlines company about their flights because it can be misused, but several statuses are provided:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(from &lt;a href=&quot;http://www.flightstats.com/go/AirportTracker/airportTracker.do#1&quot; rel=&quot;nofollow&quot;&gt;http://www.flightstats.com/go/AirportTracker/airportTracker.do#1&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Geographic Coverage - FlightStats provides definitive information for approximately 99.5% of U.S. flights, and better than 86% of flights worldwide.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Completeness - FlightStats queries multiple sources to create a record for each flight enabling us to offer a broader range of information (for example, gate information).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Accuracy - We have invested heavily in the areas of parsing, interpretation and error checking and developed the logic that enables handling of difficult issues such as cancellations, diversions and changing schedules.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Codeshare Support - Our codeshare logic enables us to deliver flight information for both the operating and the marketing carriers, filling what is often a major gap in coverage.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Real-time data sources include:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;FAA ASDI Data Feed&lt;/li&gt;&#xA;  &lt;li&gt;European Data Feed&lt;/li&gt;&#xA;  &lt;li&gt;GDS (Sabre, Amadeus, Apollo, Galileo)&lt;/li&gt;&#xA;  &lt;li&gt;Direct Airport / Airline Data Feeds&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;Batch data sources include:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Innovata Schedules&lt;/li&gt;&#xA;  &lt;li&gt;TSA Security Wait Times&lt;/li&gt;&#xA;  &lt;li&gt;Security Information&lt;/li&gt;&#xA;  &lt;li&gt;Health Information&lt;/li&gt;&#xA;  &lt;li&gt;Consular Information&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1461" LastEditorUserId="6" LastEditDate="2015-07-15T23:01:29.997" LastActivityDate="2015-07-15T23:01:29.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2342" PostTypeId="2" ParentId="2186" CreationDate="2014-03-16T10:41:21.010" Score="4" Body="&lt;p&gt;&lt;em&gt;Prelude: While studying for being airplane engine engineer in university I took 3 years of special military course where been taught to be military aircraft mechanic. Also forgive my possible incorrect tech terms as English isn't my native language.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While here are plenty of great answers about parachutes with detailed explanations and facts about it, I'd like to add my 2 cents about emergency ejection systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As OP has stated one on hand those systems are expensive, but this isn't the main point why those are not used in commercial aviation. There are two points to consider:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Those systems are heavy&lt;/strong&gt;. We all have seen how on commercial airlines they weigh your luggage. This is done for a reason - the airplane does not have infinite weigh capacity. If we equip standard commercial plane like Boeing 777 with eject seats there will be no free weight capacity for either passengers or their luggage. One such system (the one I have studied) weights appx 80-90 kg. Seeing standard commercial seats I'd say their weight is no more than 10-15 kg (anyone correct me if I am wrong here). However installing such systems could be done for example on private airplanes where the number of passengers is limited and thus there is some free weight capacity, but it still would be bad solution due to second point.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;In order to survive ejection procedure one should have perfect health and wear special suit&lt;/strong&gt;. Let's start from suite - you've probably seen in movies that military pilots wear special suits, those suits are designed to handle two things that happen to you during flight - depressurization and extreme acceleration. Not sure if in any movie it was shown, but this suite actually consists of network of tubes and pads that are being inflated with high pressure air through connection in pilots seat. Why there is a need in such suit? I won't talk about normal flight in those suits as we are talking about commercial airline, let's see what happens during ejection. When one is ejected, their seat is basically being launched with a rocket engine, in order to prevent damage to pilot/passenger from any parts of aircraft, he/she should be moved away of it very quickly, this means very high acceleration rate. On the other hand our body contains big amount of liquids. Now imagine what would happen if suddenly kick a glass with water? Inertia will hold liquids from moving together with glass, that means all blood in case of ejection will move down in our body - 1) leaving our brain without oxygen supply; 2) destroying blood circulation systems in bottom half of our body. With special suit (that with extra pressure on our body balances this effect) we can make sure that our body will not burst itself out with high pressure blood from below chest level. Although I myself never went through such examination, while studying we learnt that one of very important health checkups for pilots is their cardiac system, means that their heart and blood tubes will be able to handle such an extreme procedure (and this is why running is an important part of military training as it strengthens whole blood circulation system). Still having said all of that about military pilots, more than half of them while will survive ejection procedure, will blackout for some time due to low oxygen level in brain. Also as we were told while studying, even with all this training and equipment people who once went through ejection in mid-air are usually not piloting after that due to damages their body suffered (this info maybe outdated as eqipment we learnt was about 10 years old at that time). Now compare trained military aviation pilot equipped with compensation suit to the average commercial airline passenger who perhaps smokes, eats high cholesterol food and doesn't do much sports ;) What do you think will be chances of survival?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1524" LastActivityDate="2014-03-16T10:41:21.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2343" PostTypeId="2" ParentId="2186" CreationDate="2014-03-16T10:53:12.693" Score="2" Body="&lt;p&gt;As an alternate answer in that you can still get parachutes on a plane, even if the airline doesn't provide them...we had a related question over on Travel.Stackexchange.  While, as you noted, airlines don't typically provide parachutes, the TSA specifically allows you to bring your own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://travel.stackexchange.com/q/7814/101&quot;&gt;Are parachutes allowed on airplanes as cabin baggage?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short version &lt;a href=&quot;http://www.tsa.gov/travelers/airtravel/assistant/editorial_1147.shtm&quot; rel=&quot;nofollow noreferrer&quot;&gt;from the TSA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You may bring skydiving rigs with and without Automatic Activation&#xA;  Devices (AAD) as carry-on or checked luggage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1528" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2014-03-16T10:53:12.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2345" PostTypeId="1" AcceptedAnswerId="2346" CreationDate="2014-03-16T17:25:28.960" Score="13" ViewCount="958" Body="&lt;p&gt;While reading the description of ADS-B given on the FR24 website (&lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot;&gt;ADS-B How it works&lt;/a&gt;), I came across this sentence:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The farther away from the receiver an aircraft is flying, the higher it must fly to be covered by the receiver.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is the relation between height and coverage in this case?&lt;/p&gt;&#xA;" OwnerUserId="1534" LastEditorUserId="19" LastEditDate="2015-02-18T20:09:11.327" LastActivityDate="2015-02-18T20:09:11.327" Title="What is the relation between aircraft altitude and ADS-B coverage?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2346" PostTypeId="2" ParentId="2345" CreationDate="2014-03-16T17:35:54.563" Score="14" Body="&lt;p&gt;The ADS-B signal used by FR24 is transmitted on 1090 MHz. Signals at that frequency do not follow the curvature of the earth very well. They work best in line of sight. Aircraft far away from the receiver must be at high altitude to be above the horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 1000ft, the horizon is about 33 nautical mile away. Aircraft further away will be shielded below the horizon. For 40000ft, the horizon is about 220 nautical mile away. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v3dnQ.png&quot; alt=&quot;L-Band signal horizon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to a slight refraction of the signal the practical range is about 15% further. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-02-17T20:03:05.030" LastActivityDate="2015-02-17T20:03:05.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2347" PostTypeId="1" CreationDate="2014-03-16T18:31:25.873" Score="3" ViewCount="1633" Body="&lt;p&gt;The Boeing 777 has fore and aft pressurisation switches (see example &lt;a href=&quot;https://aviation.stackexchange.com/a/2329/972&quot;&gt;here&lt;/a&gt;). If the aft switch was forgotten on takeoff, could this cause a loss of cabin pressurisation when the aircraft reaches altitude?&lt;/p&gt;&#xA;" OwnerUserId="1533" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-03-18T06:25:43.213" Title="On a 777 what would happen if the aft pressurization switch was accidentally left closed?" Tags="&lt;emergency&gt;&lt;accidents&gt;&lt;boeing-777&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2348" PostTypeId="2" ParentId="2347" CreationDate="2014-03-16T19:18:08.503" Score="7" Body="&lt;p&gt;From my previous source in &lt;a href=&quot;https://aviation.stackexchange.com/q/2328/39&quot;&gt;that incapacitation question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Two outflow valves are installed: one forward and one aft. Normally,&#xA;  most of the outflow is through the aft outflow valve. This improves&#xA;  ventilation and smoke removal. &lt;strong&gt;Cabin altitude and full ventilation&#xA;  rates can be maintained by either valve&lt;/strong&gt;. &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=B777-Air_Systems.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-03-16T21:31:35.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2349" PostTypeId="2" ParentId="2291" CreationDate="2014-03-16T21:28:11.517" Score="3" Body="&lt;p&gt;In relation to missing flight MH370, and the radar coverage of that region, please see the link to the Department of Civil Aviation Malyasia's primary and secondary (SSR) radar services in the region. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aip.dca.gov.my/aip%20pdf/ENR/ENR%201/ENR%201.6/Enr1_6.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://aip.dca.gov.my/aip%20pdf/ENR/ENR%201/ENR%201.6/Enr1_6.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first page lists all the Primary and Secondary (SSR) civil/military radar services and then page 10 graphically represents the 200NM SSR ranges of each station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to determine how much of the map is covered by primary radar only, you can match the names of the stations on the map with the table on page 1, and use the 200NM area as a guide to determine the primary radar reach of each station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, the BBC website shows how flight MH370 changed course with this graphic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://news.bbcimg.co.uk/media/images/73602000/jpg/_73602232_china_malaysia_plane9_624.jpg&quot; alt=&quot;bcc image of flight MH370 path&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at the radar coverage map again, we can see that this means the flight passed through the primary radar station coverage of Kota Bharu, listed as 1.1.4(g).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps, and I hope all the people are found safe.&lt;/p&gt;&#xA;" OwnerUserId="1536" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.867" LastActivityDate="2014-03-16T21:28:11.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2350" PostTypeId="1" CreationDate="2014-03-17T00:44:23.823" Score="21" ViewCount="2613" Body="&lt;p&gt;Why is the first letter in US registration numbers 'N'? Other countries seem to use a letter significant to their country, for instance 'G' for &lt;b&gt;G&lt;/b&gt;reat Britain, 'F' for &lt;b&gt;F&lt;/b&gt;rance, 'D' for Germany (presumably for &lt;b&gt;D&lt;/b&gt;eutschland), and 'JA' for &lt;b&gt;Ja&lt;/b&gt;pan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does 'N' have any significance at all?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-03-17T01:04:47.377" LastActivityDate="2020-04-23T21:41:19.997" Title="Where did the US 'N' registration letter come from?" Tags="&lt;usa&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2351" PostTypeId="2" ParentId="2350" CreationDate="2014-03-17T00:59:34.380" Score="17" Body="&lt;p&gt;The origins of this can be traced back to CINA (the Commission Internationale de Navigation Aerienne / the Convention for the Regulation of Air Navigation) established as part of the Paris Peace Conference immediately after WWI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A part of this conference was the adoption of a system of international aircraft identification still in use today. The U.S. delegation was allocated &quot;N&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of theories exist as to &lt;em&gt;why&lt;/em&gt; &quot;N&quot; was chosen specifically, and there's &lt;a href=&quot;http://www.aahs-online.org/articles/N-number.php&quot;&gt;a great article about it&lt;/a&gt; over at the American Aviation Historical Society.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theories range from, the largest number of states begin with the letter N; to the recognition of the development of wireless communications by the U.S. Navy that had been using &quot;N&quot; as the prefix to its station call-sign identifiers since 1909.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-17T05:44:42.683" LastActivityDate="2014-03-17T05:44:42.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2353" PostTypeId="1" AcceptedAnswerId="2397" CreationDate="2014-03-17T02:39:44.697" Score="10" ViewCount="1312" Body="&lt;p&gt;I'd imagine there are probably reasons behind the choice of food that airlines serve, and I'm wondering what those reasons are?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess that Air India probably serves more curries than American Airlines, but what other considerations are taken into account? Presumably weight is one.&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-03-18T02:51:46.097" Title="How do airlines choose what food to serve?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2017-01-27T06:31:11.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="2354" PostTypeId="1" AcceptedAnswerId="2357" CreationDate="2014-03-17T02:56:14.237" Score="101" ViewCount="78343" Body="&lt;p&gt;When planes come off the assembly line at the factory, they're green:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/A2B8w.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why are most painted white? Surely a darker colour would hide dirt better?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MxLZl.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason planes are traditionally white?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here's a clip that shows a Boeing 747 being painted:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Lk7UFNeRDSQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:22:07.927" LastActivityDate="2020-07-01T18:07:16.853" Title="Why are planes generally painted white?" Tags="&lt;airliner&gt;&lt;livery&gt;" AnswerCount="15" CommentCount="12" FavoriteCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2355" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T03:23:43.947" Score="5" Body="&lt;p&gt;It's quite simple actually: White paint is both cheaper and lighter than paint with colorant added to it.  Both of these are important when trying to reduce cost at an airline!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-17T03:23:43.947" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2356" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T03:27:10.353" Score="74" Body="&lt;p&gt;The green coating is a primer (historically zinc chromate, these days zinc phosphate is used as it's less of an environmental hazard) - While you could theoretically fly around like that it is a rather ugly shade of green, so most folks (and airlines) tend to paint their aircraft some other color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So why white?&lt;/strong&gt;&lt;br&gt;&#xA;White has a few advantages, but the two biggest ones I can think of are these:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;White is a nice, neutral base color.&lt;/strong&gt;&lt;br&gt;&#xA;Artists typically start out with a white canvas, or white paper - it's a color associated with &quot;blank&quot; and &quot;clean&quot; (the latter moreso if you actually &lt;em&gt;wash&lt;/em&gt; the aircraft, of course...). &#xA;Starting with a white base coat allows the airline's marketing department to paint whatever livery they want on their flying billboards.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;White doesn't fade.&lt;/strong&gt;&lt;br&gt;&#xA;Or perhaps it's more accurate to say &quot;you don't really &lt;em&gt;notice&lt;/em&gt; when white fades.&quot;. &#xA;An average airliner will have several paint jobs during its service life, but the longer you can go between having to reprint the plane the better, and if you don't have to worry about the paint fading and looking old for a good long while you cans stretch the time between paint jobs without having your passengers start making snide comments about your fleet of flying hoopties.&lt;br&gt;&#xA;All colored paints will eventually fade from exposure to sun and the elements, particularly exposure to the sun at 30,000 feet, where substantially more UV radiation is hitting the paint and accelerating the fading process.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of course there's nothing that says the base coat HAS to be white: Southwest has a very attractive blue/red/orange livery, and American Airlines has traditionally incorporated polished aluminum in their livery (which also affords a substantial weight savings, by not priming &amp;amp; painting the entire body of the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/likly.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/liklym.jpg&quot; alt=&quot;Current Southwest livery&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/9H8Il.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9H8Ilm.jpg&quot; alt=&quot;American Airlines old livery (MD-80)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-17T03:27:10.353" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2357" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T03:36:29.147" Score="84" Body="&lt;p&gt;&lt;strong&gt;White has some significant thermal advantages over color.&lt;/strong&gt; In most cases, this is probably just a benefit in terms of keeping the cabin slightly cooler. In the case of 'plastic' airplanes (those built with composite construction), some airframes &lt;em&gt;require&lt;/em&gt; the use of white paint on upper surfaces to keep some elements within limits. &lt;a href=&quot;http://www.diamondaircraft.com/library/19/10/Temperature_limitation.pdf&quot; rel=&quot;noreferrer&quot;&gt;Early Diamond Aircraft designs had a 38° C&lt;/a&gt; outside air temperature limit, &lt;strong&gt;past which the main spar is not considered structurally sound&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, Diamond would only manufacture aircraft with predominantly white upper surfaces, as darker surfaces could result in significant heat gain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/reviews/182565-1.html?redirected=1&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wDROQ.jpg&quot; alt=&quot;DA-20 55C overtemp indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avweb has &lt;a href=&quot;http://www.avweb.com/news/reviews/182565-1.html?redirected=1&quot; rel=&quot;noreferrer&quot;&gt;an article on the DA-20&lt;/a&gt; that shows the bright red &lt;strong&gt;over-temp indicator&lt;/strong&gt; that raises the maximum temperature to 55° C, &lt;a href=&quot;http://www.diamondaircraft.com/library/19/10/Temperature_limitation.pdf&quot; rel=&quot;noreferrer&quot;&gt;added as a Service Bulletin&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-17T04:49:21.607" LastActivityDate="2014-03-17T04:49:21.607" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2358" PostTypeId="1" AcceptedAnswerId="2394" CreationDate="2014-03-17T03:42:57.133" Score="20" ViewCount="10347" Body="&lt;p&gt;Theoretically speaking, let's say we're flying from Portugal to Cuba, on a Chinese-owned airliner. Whilst over the Atlantic, a crime is committed, and we land in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which country is responsible for prosecution? How is this determined?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-17T03:57:04.443" LastActivityDate="2019-04-30T02:22:41.777" Title="Which country is responsible for prosecution if a crime is committed over international waters?" Tags="&lt;international&gt;&lt;transatlantic&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2359" PostTypeId="1" AcceptedAnswerId="2374" CreationDate="2014-03-17T04:27:12.730" Score="36" ViewCount="37083" Body="&lt;p&gt;Taking &lt;a href=&quot;http://en.wikipedia.org/wiki/EasyJet&quot;&gt;easyJet&lt;/a&gt; as an example, they have &lt;a href=&quot;http://corporate.easyjet.com/~/media/Files/E/Easyjet-Plc-V2/pdf/content/press-info-kit.pdf&quot;&gt;a fleet&lt;/a&gt; of over 200 A319's and A320's. At a price tag of around \$90m per plane, that equates to about \$18bn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that their turnover for 2012/13 was around \$7bn, and their net profit was only \$660m, how exactly do they own so many planes? Are they financed long-term? Are they leased?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are the deals structured for the big airlines when purchasing new planes?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="3386" LastEditDate="2017-02-03T19:27:04.623" LastActivityDate="2018-04-25T07:37:11.930" Title="How do airlines pay for their planes?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;cost&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2360" PostTypeId="1" AcceptedAnswerId="2378" CreationDate="2014-03-17T04:44:58.093" Score="32" ViewCount="52501" Body="&lt;p&gt;What are the advantages of a forward-swept wing vs. a rearward swept one?&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Grumman_X-29&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/a/ac/X-29_in_Banked_Flight.jpg/961px-X-29_in_Banked_Flight.jpg&quot; alt=&quot;X-29 - forward swept&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Image credit: NASA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-86_Sabre&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/North_American_F86-01.JPG/640px-North_American_F86-01.JPG&quot; alt=&quot;F-86 - rearward swept&quot;&gt;&lt;/a&gt;&#xA;Image credit: &lt;a href=&quot;http://en.wikipedia.org/wiki/User:Paulmaz&quot; rel=&quot;noreferrer&quot;&gt;Paul Maritz&lt;/a&gt; / Wikimedia&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.880" LastActivityDate="2016-12-28T11:21:28.977" Title="What are the advantages of a forward-swept wing over a rearward-swept wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2361" PostTypeId="1" AcceptedAnswerId="2389" CreationDate="2014-03-17T05:00:29.877" Score="28" ViewCount="26879" Body="&lt;p&gt;One thing I guess a lot of people wonder is: what happens you flush the toilet in an aeroplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it fall out the belly of the plane and disintegrate? :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LWlqs.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mirror.co.uk/news/world-news/an-aeroplane-s-us-woman-4345169&quot; rel=&quot;noreferrer&quot;&gt;A kiwi woman complains&lt;/a&gt; that &quot;aeroplanes are taking a s**t on her driveway&quot;, beneath the flight path. Is there any way this might actually happen?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-09-30T02:48:27.790" LastActivityDate="2015-04-14T21:13:10.870" Title="Where does my pee go when I flush at 35,000 ft?" Tags="&lt;passenger&gt;&lt;airliner&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2362" PostTypeId="2" ParentId="2361" CreationDate="2014-03-17T05:05:55.987" Score="9" Body="&lt;p&gt;It is stored and then disposed of when plane touches down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://answers.yahoo.com/question/index?qid=20070531141632AAMWo7c&quot;&gt;Yahoo! Answers&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_lavatory&quot;&gt;Wikipedia: Aircraft lavatory&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="97" LastEditDate="2014-03-17T06:41:34.293" LastActivityDate="2014-03-17T06:41:34.293" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2363" PostTypeId="1" AcceptedAnswerId="2371" CreationDate="2014-03-17T05:16:20.033" Score="5" ViewCount="690" Body="&lt;p&gt;During WWII, &lt;a href=&quot;http://www.11points.com/News-Politics/11_Companies_That_Surprisingly_Collaborated_With_the_Nazis&quot; rel=&quot;nofollow noreferrer&quot;&gt;a number of German companies&lt;/a&gt; received financial backing and slave labourers from the government at the time. Companies such as Hugo Boss, Volkswagen and Lufthansa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/64035/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A thread on Airliners.net&lt;/a&gt; from 1999 mentions a documentary showing Lufthansa planes flying with the Swastika on their tail. I found this image online:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hbTD6.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the story behind Lufthansa's involvement with the National Socialist Party? Did they indeed receive large monetary backing from the then-government?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T20:39:12.053" LastActivityDate="2016-01-17T20:23:09.753" Title="Did the NSDAP help to fund Lufthansa?" Tags="&lt;military&gt;&lt;lufthansa&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2364" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T05:24:16.783" Score="12" Body="&lt;p&gt;White makes it easier to spot another plane in the air, since white shows up well against the ground.  This is why many early planes were colored on the bottom half and white/silver for the rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this matters much less with modern IFR equipment and doesn't matter really at all with high-altitude jets, but old habits die hard, I guess.&lt;/p&gt;&#xA;" OwnerUserId="1540" LastActivityDate="2014-03-17T05:24:16.783" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2365" PostTypeId="1" AcceptedAnswerId="2370" CreationDate="2014-03-17T06:51:14.663" Score="10" ViewCount="2982" Body="&lt;p&gt;Of course, we all know that you're not exactly treated like a rockstar on Ryanair, and their CEO &lt;a href=&quot;http://www.dailymail.co.uk/travel/article-1263905/Ryanair-toilet-charges-phased-in.html&quot; rel=&quot;noreferrer&quot;&gt;wants to charge us £1 to use the toilet&lt;/a&gt;; but still, how can they offer flights for a penny?!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at flights with budget airlines, they usually end up costing more, with taxes etc added on, but I've seen Ryanair offering flights for literally a penny, all in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GYCpM.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T20:40:57.123" LastActivityDate="2018-02-28T09:03:00.053" Title="How can Ryanair offer flights for a penny?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;&lt;cost&gt;&lt;ryanair&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2366" PostTypeId="1" CreationDate="2014-03-17T07:01:31.963" Score="20" ViewCount="2519" Body="&lt;p&gt;I've now seen several landing strips up close and there are lots of tire tracks from planes' landing wheels. I wonder if it somehow modifies the properties of landing strips to make for poorer landing conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do landing strips suffer from lots of tire tracks?&lt;/p&gt;&#xA;" OwnerUserId="1542" LastEditorUserId="97" LastEditDate="2014-03-17T07:03:48.227" LastActivityDate="2018-11-08T14:19:08.297" Title="Do landing strips suffer from landing wheel tire tracks?" Tags="&lt;landing&gt;&lt;runways&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2367" PostTypeId="2" ParentId="2366" CreationDate="2014-03-17T07:07:10.050" Score="20" Body="&lt;p&gt;It does indeed degrade performance, and runways (and their lights) have to be routinely cleaned of rubber. The FAA specifies safe friction levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airfield_rubber_removal&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; has this to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The build up of rubber affects the level of friction of the runway, most noticeably as a reduction in braking and ground handling performance. This can lead to incidents such as runway overrun or a lateral slide off the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some runways are particularly poor:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p0nec.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-17T07:13:25.313" LastActivityDate="2014-03-17T07:13:25.313" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2368" PostTypeId="2" ParentId="2363" CreationDate="2014-03-17T08:08:33.747" Score="12" Body="&lt;p&gt;NSDAP was the elected ruling party in Germany from 1933 to 1945 (only the first part of it elected though); thus Lufthansa was given government money, not &quot;Nazi&quot;-money. During this time, they made the Swastika the flag of Germany. American Airlines sport the American flag all over their tail, and I'm sure they (at some point) have received government money as well. If you replace every occurrence of &quot;Nazis&quot; in your question (including title) with &quot;government&quot;, you'll notice it becomes slightly less provocative, and the parallels to other airlines and other countries become readily apparent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the war started, I would assume the military requisitioned all the assets they needed including airplanes and services from Lufthansa. I'm not much of an historian though, so I can't give you any details, but I'm sure they're out there to find. I realize this doesn't really answer your question (Lufthansa's involvement with the German government), the point I'm trying to make is that it's very hard to answer, as with any airline and any government.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-03-20T08:36:34.157" LastActivityDate="2014-03-20T08:36:34.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2369" PostTypeId="2" ParentId="2365" CreationDate="2014-03-17T08:56:11.470" Score="11" Body="&lt;p&gt;One of the reasons Ryanair has some benefits on other airlines are the subsidies they get from airports.  Basically taxpayers are paying a part of your ticket (&lt;a href=&quot;http://www.businessweek.com/articles/2013-07-05/eu-takes-aim-at-airport-subsidies-and-ryanair&quot; rel=&quot;nofollow noreferrer&quot;&gt;See this businessweek article&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next to that they fly on relatively cheap times and small airports which means they have to pay less to an airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly; as you know that charge fees for everything. Whether you want to bring an extra bag, something to drink or like to go to the toilet in the feature, you'll have to pay for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder whether they can make money when people don't want to make use of the 'extra's' they offer. I don't think so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe someone can do the math and calculate what an average Ryanair flight costs (&lt;a href=&quot;https://aviation.stackexchange.com/questions/654/whats-the-typical-cost-and-its-breakdown-for-a-long-haul-commercial-flight&quot;&gt;See this answer&lt;/a&gt;) and how much money they get from only the tickets.&lt;/p&gt;&#xA;" OwnerUserId="432" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-03-17T08:56:11.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2370" PostTypeId="2" ParentId="2365" CreationDate="2014-03-17T09:02:55.580" Score="17" Body="&lt;p&gt;Besides @Sebass van Boxel's answer, I'd like to add the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was talking to a Fastjet pilot (ex easyJet) and he was telling me that obviously not all seats are available for a cheap price.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you book early you will get a special price but try booking a day before and you will see.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has been said, a lot of money is made on all the extra services such as luggage, food, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what he told me, the profit on each flight for easyJet is minimum \$400 per flight at 96% full &amp;mdash; which is not much, but consider that easyJet has something like 1,000 flights a day and that means \$400,000/day profit. Not bad...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That how the money is made.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="97" LastEditDate="2014-04-20T18:25:56.803" LastActivityDate="2014-04-20T18:25:56.803" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2371" PostTypeId="2" ParentId="2363" CreationDate="2014-03-17T09:27:23.580" Score="6" Body="&lt;p&gt;Look up the idea of a national airline, a flag carrier, and drop your attitude that for whatever reason they should have been banned from operating because they had been such.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aeroflot carried the flag of the USSR proudly, the USSR killed more people than Nazi Germany ever did. Totally irrelevant. They're their country's flag carrier, so they show the flag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, this has nothing to do with anything military. Lufthansa was state owned at the time (and indeed into the 1990s), so of course they flew the then current flag of the state, which for a decade happened to include the Swastika.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the post-WW2 Lufthansa is a different company from the pre-WW2 Lufthansa. It was incorporated in 1953 and purchased the name Lufthansa on the open market as a trade name, an old and proud name in European aviation, a name associated with quality and reliability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They still bear the national flag of Germany to this date, albeit a smaller one. But at the time it was very common for airlines to show the national flag very large and proud on the tail fin or fuselage.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="97" LastEditDate="2014-03-18T01:04:15.940" LastActivityDate="2014-03-18T01:04:15.940" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2372" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T09:33:34.183" Score="19" Body="&lt;p&gt;Two reasons for white I've been told many times are:&lt;br/&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;white paint is cheaper than other colours (either because it costs less and/or weighs less)&lt;/li&gt;&#xA;&lt;li&gt;white makes it easier to apply names and logos of other companies when leasing your aircraft to someone else. Saves a trip to the paint shop, instead you just apply stickers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both make sense, but whether they're the main reason I don't know.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-17T09:33:34.183" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2373" PostTypeId="2" ParentId="2359" CreationDate="2014-03-17T09:39:24.580" Score="20" Body="&lt;p&gt;Much of course depends on the companies involved, but there's several common schemes in place:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Lease&lt;/strong&gt;&lt;br&gt;&#xA;Effectively like your lease car, you pay a fee per month or year over a contract period. At the end you either get a right to purchase the aircraft for a nominal price or it reverts to the lease company, or you extend the lease.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Purchase Outright&lt;/strong&gt;&lt;br&gt;&#xA;Yes, you can pay cash. Especially older companies may have the cash reserves to pay for new aircraft out of pocket.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Bank Loans&lt;/strong&gt;&lt;br&gt;&#xA;Either a bank or the manufacturer underwrites a loan with the aircraft as collateral. Pretty similar to a mortgage on your house&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Trade in&lt;/strong&gt;&lt;br&gt;&#xA;Like buying a new car, you might get a fair price for that old aircraft you had sitting around&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Subsidies&lt;/strong&gt;&lt;br&gt;&#xA;There's still a lot of national prestige involved in some countries with getting foreign airlines to fly your product. Some aircraft manufacturers as a result can deliver well under the list price to foreign airlines because such sales may be heavily subsidised by their governments.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="900" LastEditorUserId="64" LastEditDate="2014-03-17T15:31:20.640" LastActivityDate="2014-03-17T15:31:20.640" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2374" PostTypeId="2" ParentId="2359" CreationDate="2014-03-17T10:12:08.557" Score="41" Body="&lt;p&gt;The overwhelming majority of major airlines do lease at least some of their aircraft. And most airlines who choose to buy do not end up paying that full price tag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of Easyjet, around half their fleet is leased (as of 2013). Leasing allows airlines with weak balance sheets or with poor future prospects to increase capacity without locking capital.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, the largest aircraft owners are aircraft leasing companies. For example, GECAS (General Electric Capital Aviation Services), the largest aircraft lessor, currently owns around 1,700 aircraft, being operated by 230 airlines around the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other (not state-owned and generally low cost) airlines, such as Ryanair, who are fond of owing most of their aircraft. What Ryanair does is negotiate very good procurement deals with Boeing (by buying large packs of planes, all being B-737s), use them for around 5 years, and then sell them before their price has gone down too low. This takes a burden on their debt levels, but seems to work for them so far on the long run.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This aircraft resell value is an important aspect to consider when comparing leasing vs purchasing, as well as tax incentives derived from amortization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Legacy carriers (many of them state owned), on the other hand, have a tendency to purchase most of their fleet, and keeping them around for the full lifespan of the machine (around 30 years).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual price a company pays for a given aircraft is not public (understandably) and most figures you would be able to find are related to &quot;list prices&quot;. However, in 2005 Ryanair was forced to disclose facts about one of the massive (by the time) purchases of Boeing aircraft. Apparently, they paid &lt;a href=&quot;http://seattletimes.com/html/businesstechnology/2002250601_ryanair23.html&quot;&gt;less than half of the public list price&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More current data on the actual price airlines pay for Boeing planes can be found &lt;a href=&quot;http://theblogbyjavier.com/2014/02/15/boeing-commercial-aircraft-discounts-update-for-2013/&quot;&gt;here&lt;/a&gt;, where Javier Irastorza analyses the discounts Boeing is applying to their aircraft based on a balance sheet assessment.&lt;/p&gt;&#xA;" OwnerUserId="1128" LastEditorUserId="1128" LastEditDate="2014-04-15T11:18:04.513" LastActivityDate="2014-04-15T11:18:04.513" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2375" PostTypeId="1" AcceptedAnswerId="2379" CreationDate="2014-03-17T10:30:52.853" Score="15" ViewCount="1818" Body="&lt;p&gt;In companion to the other &lt;a href=&quot;https://aviation.stackexchange.com/questions/2366/do-landing-strips-suffer-from-landing-wheel-tire-tracks&quot;&gt;question asking about wheel tire tracks&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes come down and stop with a significant amount of force which I would expect to cause either &lt;a href=&quot;http://en.wikipedia.org/wiki/Rut_%28roads%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;rutting&lt;/a&gt; or potholes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are runways susceptible to ruts and potholes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And do these cause significant issues for landing planes?&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-03-18T03:27:40.107" Title="Do landing strips suffer from potholes or rutting?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;runways&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2376" PostTypeId="1" AcceptedAnswerId="2377" CreationDate="2014-03-17T13:06:56.813" Score="10" ViewCount="1695" Body="&lt;p&gt;It is becoming accepted that the Boeing 777 is the world's safest aircraft. There must be a reason for this of course, and aircraft designers should know it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is, can't we take all the safety merits of a B777 and copy them into other models and bring all airplanes to the same level of safety?&lt;/p&gt;&#xA;" OwnerUserId="1534" LastEditorUserId="97" LastEditDate="2015-05-03T01:56:00.147" LastActivityDate="2020-01-31T16:55:36.947" Title="Can the safety of the Boeing 777 be extended to other models?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;boeing-777&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2377" PostTypeId="2" ParentId="2376" CreationDate="2014-03-17T14:32:01.733" Score="18" Body="&lt;p&gt;What's the &quot;safest aircraft&quot; depends in large part on who operates it, how they operate it, and where.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For many operators the 777 will be their prestige airliner, being assigned the most senior, most experienced, crews, the best maintenance, etc. etc..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That alone will mean less incidents and accidents than other types. They also have the range and ceiling to be able to fly around or over most serious weather. A 30 minute detour on a 10 hour trip can be made up, a 30 minute detour on a 1 hour trip in a 737 or A320 can't be (even if the aircraft would have the spare fuel to fly that detour).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest is mostly statistics. I seriously doubt there have been statistically more accidents per hour flown or per rotation on say an A340 as compared to a 777. There have been more airframe losses, but those include several lost on the ground due to them being stuck on airports in warzones (think what happened on Sri Lanka where Tamil separatist mortar bombs destroyed several airliners on the ground, damaging the until then flawless safety record of the type).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been AFAIK 3 777 hull losses (including the missing MH370) in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the far higher number of say 737s in operation, and the far longer service history of that type, often with operators with shady operational procedures (more than a few are for example blacklisted by the EU) it's little surprise there have been more hull losses among the type. But comparing say the 737-900 only with the 777, with somewhat similar technology and number in service, as well as similar prestige level for crew assignments, you'll find a similar safety record.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="11215" LastEditDate="2020-01-31T16:55:36.947" LastActivityDate="2020-01-31T16:55:36.947" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="2378" PostTypeId="2" ParentId="2360" CreationDate="2014-03-17T15:50:56.310" Score="26" Body="&lt;p&gt;There have only been a few aircraft built with forward-swept wings. Most notably was the X-29, which you have pictured above. Russia/USSR built one more recently in 1997, the Sukhoi Su-47. One of the biggest claims as to the superiority or an advantage of a forward-swept wing was increased maneuverability. However, in the case of the X-29, as noted in the &lt;em&gt;Flying Qualities Evaluation of the X-29A Research Aircraft&lt;/em&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The high pitch instability of the airframe led to wide predictions of extreme maneuverability. This perception has held up in the years following the end of flight tests. Air Force tests did not support this expectation. For the flight control system to keep the whole system stable, the ability to initiate a maneuver easily needed to be moderated. This was programmed into the flight control system to preserve the ability to stop the pitching rotation and keep the aircraft from departing out of control. As a result, the whole system as flown (with the flight control system in the loop as well) could not be characterized as having any special increased agility. It was concluded that the X-29 could have had increased agility if it had faster control surface actuators and/or larger control surfaces.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Su-47 was indeed a highly maneuverable aircraft, capable of pulling 9 Gs, however, its immediate predecessor, the Sukhoi Su-37, was capable of pulling &lt;em&gt;10 Gs&lt;/em&gt;. So it's not clear whether a forward swept wing has any real positive impact on maneuverability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, stall characteristics are very different. Air tends to travel towards the rearmost end of the wing. On a standard configuration (Rear-swept wing), this of course moves from the wing root to the wingtip. On a forward-swept wing, however, this moves from the wingtip to the wing root. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MLcNp.png&quot; alt=&quot;Airflow characteristics of swept wings (image courtesy of wikipedia)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As a result, the dangerous tip stall condition of a backwards-swept design becomes a safer and more controllable root stall on a forward swept design. This allows full aileron control despite loss of lift, and also means that drag-inducing leading edge slots or other devices are not required. With the air flowing inwards, wingtip vortices and the accompanying drag are reduced, instead the fuselage acts as a very large wing fence and, since wings are generally larger at the root, this improves lift allowing a smaller wing. As a result maneuverability is improved, especially at high angles of attack. At transonic speeds, shockwaves build up first at the root rather than the tip, again helping to ensure effective aileron control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because of the capability of the X-29 to have the tips of its wings &lt;em&gt;bend down&lt;/em&gt; when at high angles of attack, the X-29 remained controllable at an angle of attack of 67 degrees. However, thanks to modern advances in thrust vectoring, the F-22 Raptor is capable of &lt;em&gt;sustaining&lt;/em&gt; an angle of attack over 60 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With inherent instability and problems with extra stresses on the airplane for only moderate or supposed but not observed gains in instability, it is unlikely we will see combat aircraft with forward swept wings any time in the near future. Other technologies have enabled similar or enhanced performance without the need for novel concepts. &lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-03-17T15:50:56.310" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2379" PostTypeId="2" ParentId="2375" CreationDate="2014-03-17T15:59:11.503" Score="18" Body="&lt;p&gt;Yes, they do, and it can indeed pose significant problems for aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Asphalt runways are susceptible to ruts (because asphalt isn't really solid - it's solid aggregate suspended in an &lt;em&gt;extremely viscous&lt;/em&gt; liquid). The friction (heat) from landings partially melts the asphalt, and the weight of the aircraft slowly pushes it outward away from the landing gear, creating ruts. (There are also other ways you can cause ruts on asphalt runways, such as &lt;a href=&quot;http://www.lcsun-news.com/fastsearchresults/ci_4463048&quot; rel=&quot;noreferrer&quot;&gt;landing overweight aircraft on them on extremely hot days&lt;/a&gt;).&lt;br&gt;&#xA;Concrete runways are theoretically less susceptible to rutting, but have their own maintenance challenges.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Runways can also develop potholes, cracks, and spalling - just like a road surface.&lt;br&gt;&#xA;Because a pothole can cause loss of control on landing (if the landing gear falls into it and blows a tire or yanks the plane to one side), or serious damage to aircraft engines (if some of the material ejected from the pothole gets pulled into a jet engine's intake or kicked up by a propeller) airports take a lot of effort to prevent (and where necessary, repair) this kind of damage, and &lt;a href=&quot;http://www.atlanta-airport.com/HJN/2008/06/tech.htm&quot; rel=&quot;noreferrer&quot;&gt;routinely inspect their runways&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports also do a lot of preventative maintenance on their runways, sealing open cracks and joints in the pavement material to prevent water from infiltrating under the runway and causing potholes (see the image below - click to enlarge).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Lea7S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lea7S.jpg&quot; alt=&quot;FRG Pavement Examples&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FAA has a lot of information on &lt;a href=&quot;http://www.faa.gov/airports/engineering/pavement_design/&quot; rel=&quot;noreferrer&quot;&gt;runway pavement design&lt;/a&gt;, which I will affectionately call &quot;More than anyone ever wanted to know about runway design, and never asked!&quot;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-17T15:59:11.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2380" PostTypeId="2" ParentId="2328" CreationDate="2014-03-17T17:13:06.417" Score="13" Body="&lt;p&gt;Yes, I think it would be very easy for the pilot in command of a 777 to do this &amp;mdash; here's one scenario:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ask the copilot to get a glass of water and lock the cockpit door behind him&lt;/li&gt;&#xA;&lt;li&gt;Don and activate the oxygen mask&lt;/li&gt;&#xA;&lt;li&gt;Close the engine bleed air valves that supply cabin pressure&lt;/li&gt;&#xA;&lt;li&gt;Open the controlled outflow valves to equalize cabin pressure to altitude pressure&lt;/li&gt;&#xA;&lt;li&gt;Put the passenger/supernumerary oxygen to &quot;reset&quot; (or pull the circuit breaker)&lt;/li&gt;&#xA;&lt;li&gt;Ascend a little bit above the service ceiling of FL 410.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;At FL 450, consciousness is measured in seconds, death in about 4 or 5 minutes.&lt;/p&gt;&#xA;" OwnerUserId="1553" LastEditorUserId="1035" LastEditDate="2014-08-03T10:11:16.227" LastActivityDate="2014-08-03T10:11:16.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2381" PostTypeId="1" AcceptedAnswerId="2383" CreationDate="2014-03-17T18:23:20.817" Score="23" ViewCount="6359" Body="&lt;p&gt;I just finished reading an &lt;a href=&quot;http://keithledgerwood.tumblr.com/post/79838944823/did-malaysian-airlines-370-disappear-using-sia68-sq68&quot;&gt;interesting post&lt;/a&gt; where the author suggests that the &lt;strong&gt;missing Malaysian Airlines flight 370 could have 'hidden' under the cover of Singapore Airlines flight 68&lt;/strong&gt; to fly to a covert airstrip. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read multiple thrillers where submarines have hidden behind the acoustic signal of large cargo vessels to mask their sound over sonar arrays, and this (at least in the book) sounds plausible. I also read another book where a bomber (flying under the identity of a commercial jet) masked a business jet to get it into an area without detection. Naturally, both examples are taken from fiction, but I'm wondering:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Would there be any hints now in retrospective to suggest they were being followed? Their transponder was off of course, but I'm wondering if for instance there might be some radio interference or static from such as large aircraft behind them? Are there every any issues when refueling aircraft do this sort of thing?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the resolution of radar? Would one be able to notice the two blips on the screen unless they were literally under or beside each other, or would it still appear as one dot on secondary radar if say they were 200 meters behind and below?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastActivityDate="2019-06-13T13:32:18.557" Title="Could an aircraft 'hide' in the aircraft shadow of another aircraft without being detected or noticed?" Tags="&lt;radar&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2382" PostTypeId="1" AcceptedAnswerId="2386" CreationDate="2014-03-17T18:30:38.627" Score="20" ViewCount="10814" Body="&lt;p&gt;I never knew much about airplanes before the tragic incident of Malaysia 370. I have been spending a lot of time on Twitter reading various articles and investigations; &lt;a href=&quot;http://www.nst.com.my/nation/general/elt-can-t-be-tampered-with-say-experts-1.508287&quot;&gt;in one of the articles I read&lt;/a&gt;, they stated that unlike transponders, &quot;black boxes&quot; cannot be turned off. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, each ELT is specifically designed for each aircraft, so it&#xA;  cannot be tampered with. You also cannot turn off the black box, as it&#xA;  runs throughout the flight, recording every 30 to 60 seconds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is it really impossible to turn off the black boxes from within the plane?&lt;/p&gt;&#xA;" OwnerUserId="1554" LastEditorUserId="22726" LastEditDate="2019-06-10T03:31:54.083" LastActivityDate="2019-06-10T03:31:54.083" Title="Like transponders, can flight recorders be turned off?" Tags="&lt;avionics&gt;&lt;flight-recorders&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2383" PostTypeId="2" ParentId="2381" CreationDate="2014-03-17T18:33:15.137" Score="33" Body="&lt;p&gt;Radar resolution is defined in terms of degrees of arc (or alternatively in steradians/solid angles) and as such, the further away from the radar, the larger volume is being sampled.  At altitude and some distance from the radar you should have a bit of leeway on how loose of a formation you can fly and show up as one contact on the radar display.  I'm not giving credence to the theory presented, but I am saying it is plausible that one aircraft could fly a formation with another and be detected as one airplane by a radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the transponder is off, the aircraft you are following will not see you on TCAS  and if you are behind them you will be visually undetectable by the crew or passengers.  If you fly above them you will be clear of their wake, so I would put behind and above the best position to shadow.  A lateral offset might be safer, but if you stray too much, you might wander into the FOV of the cabin.&#xA;I can't see any way the following airplane would cause nav or com interference in the followed airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest threat to being detected in this scenario are being seen by other airplane.  If ATC calls traffic and you see two planes in formation instead, you would probably say something.  In the case of the airplane you refer to however, it was night and if you turn all of your position lights, beacons, strobes, tail lights and if there is no moon out you might escape visual detection by a third party. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-17T18:33:15.137" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2384" PostTypeId="2" ParentId="2382" CreationDate="2014-03-17T18:37:21.670" Score="15" Body="&lt;p&gt;Generally, I'm pretty sure there's no switch for a Flight Data Recorder on the overhead panel in most aircraft, since I think it switches on automatically. However, i'm pretty sure that you can pull the corresponding fuse behind the cockpit. It's a safety thing after all, since you don't want a short circuit from the FDR causing problems to the rest of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I'm not sure of how this works on the Boeing 777 as in MAS370, it was &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Express_Flight_705&quot;&gt;attempted on FedEx flight 705&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-03-17T18:37:21.670" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2385" PostTypeId="1" AcceptedAnswerId="2387" CreationDate="2014-03-17T18:39:22.987" Score="23" ViewCount="5609" Body="&lt;p&gt;Do the manufacturers who build airplanes use their own &quot;black boxes&quot; in the planes, or are there companies whose sole purpose is to develop black boxes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in 2010 in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airblue_Flight_202&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airblue Flight 202&lt;/a&gt; incident, the black box had to be sent to France for data recovery:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;He stated that the box would be examined by &quot;foreign experts&quot; in&#xA;  Germany or France as Pakistan does not possess the equipment to decode&#xA;  the flight recorders. He also stated that the process of extracting&#xA;  information may take six months to a year. The Pakistani&#xA;  authorities decided to send the CVR and FDR to the Bureau d'Enquêtes&#xA;  et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) in&#xA;  France.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is not clear who developed that black box. Was it the same company that manufactured the airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, can the buying airline use their own black box or their own security protocols for data encryption or encoding, to avoid having to send the black box out for analysis?&lt;/p&gt;&#xA;" OwnerUserId="1554" LastEditorUserId="44851" LastEditDate="2020-01-31T10:13:00.687" LastActivityDate="2020-01-31T10:13:00.687" Title="Do aircraft manufacturers produce their own black boxes?" Tags="&lt;avionics&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="2386" PostTypeId="2" ParentId="2382" CreationDate="2014-03-17T18:40:29.160" Score="26" Body="&lt;p&gt;There is no switch for the FDR, but there is a circuit breaker and by pulling this you are removing aircraft power from the FDR.  However, this does not mean you are necessarily turning it off, as some FDR can be equipped with an internal power supply as a backup to aircraft power.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quote in the question (bolded emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;You also cannot turn off the black box&lt;/strong&gt;, as it runs throughout the flight, recording every 30 to 60 seconds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;is a case of an &quot;expert&quot; or journalist confusing the lack of an on/off switch as an inability to turn something off.  As you'll find many examples of in the media, they don't always get it right.  The circuit breaker may not be a true on/off switch, but pulling it does accomplish de-powering (assuming no internal power supply) and thus turning off the FDR.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-18T11:46:32.793" LastActivityDate="2014-03-18T11:46:32.793" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2387" PostTypeId="2" ParentId="2385" CreationDate="2014-03-17T19:10:55.533" Score="22" Body="&lt;p&gt;There's seldom a reason for manufacturers to design and build their own black boxes. It's expensive to run a production line to design, build a test a few. It's just cheaper to get an agreement with a company to make them for you. The second photo below shows a popular recurring model from Honeywell, which appears to have been used on the A330, B737 and B777.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Opening the black box can be a sensitive operation, especially if there's the fear that the chips might have been damaged. It's better to send it to somebody who's done it before rather than trying to master it on the first attempt, especially if you don't have the resources. Airplanes accidents don't happen very often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the case you're referring to, the Aircraft also appears to have been built by Airbus in Hamburg, and hence the &lt;a href=&quot;http://www.bfu-web.de/EN/Home/homepage_node.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;German Accident Board&lt;/a&gt; automatically gets involved as well, much like how the NTSB gets involved in all Boeing crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jO2k7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jO2k7.jpg&quot; alt=&quot;smash&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://img.naij.com/n/00/c/plane_black_box.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;naij.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A smashed up flight data recorder.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7lyQd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7lyQd.jpg&quot; alt=&quot;asiana crash&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://i.dailymail.co.uk/i/pix/2013/07/08/article-2358016-1AB58B52000005DC-173_964x641.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;dailymail.co.uk&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A photo from the NTSB with the Asiana flight 214 recorders&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason for this is if there might be political motives behind the crash, it's preferred to send it to a third party for analysis which is less susceptible to bias or interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I gather correctly, data on the flight data recorder won't be encrypted at all- it will be fed out as serial data, but you will need the devices and software to understand this information, and if the outside connection is broken, you'll need to work your way to the chips themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V3umo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V3umo.jpg&quot; alt=&quot;readout&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.flightdata.com.au/files/qnrzxfgffs/FDS--020712-002--w420h280--cr--w420h280.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;com.au&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Photo showing apparently how black box are 'read'.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, sending it to the company is not always a good idea- they might have motives to change the truth, especially if it was caused by dodgy maintenance or bad training, nor to the manufacturer, if it was production error. The accident investigation board is the best people for this matter. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-22T19:42:57.350" LastActivityDate="2019-02-22T19:42:57.350" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="2388" PostTypeId="2" ParentId="2366" CreationDate="2014-03-17T19:40:18.177" Score="12" Body="&lt;p&gt;The Runway friction level is affected by accumulation of rubber deposits (in the touchdown zone) on the runway. Periodic removal of the deposits is needed to maintain the highest possible friction level. On busy runways rubber deposit accumulation if inevitable, runway maintenance needs to address this. When the actual runway friction level is below the minimum friction level, a 'slippery when wet' NOTAM is devised or another runway is designated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detailed information about friction, measurement and contamination can be found &lt;a href=&quot;http://www.skybrary.aero/index.php/Runway_Surface_Friction&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a side note: next to rubber deposits the paint used for markings on runways and taxiways contains a certain amount of sand to increase its friction.&lt;/p&gt;&#xA;" OwnerUserId="1470" LastEditorUserId="-1" LastEditDate="2018-11-02T15:38:09.487" LastActivityDate="2018-11-02T15:38:09.487" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2389" PostTypeId="2" ParentId="2361" CreationDate="2014-03-17T19:46:47.683" Score="29" Body="&lt;p&gt;I can speak for the most common commercial models (the 7x7s, A3xxs and the like) via an engineer friend.  All of these models flush into a tank which is emptied on the turnaround.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Vulcans, I can speak with first hand experience.  Each crew member had a stainless steel &quot;pee tube&quot;, a funnel, which fed into a rubber bladder.  They are emptied and cleaned during the after flight inspection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was changing a radio under the rear crew table where the electronics, navigator and radar operator sat.  This involved squeezing down behind the seats to lie under the table, disconnecting and unfastening the radio, hauling onto your chest then pushing it up onto one of the seats and reversing the process to get out from under the table.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I pushed the radio up onto the seat, I knocked one of the pee tubes and bladders out of it's clip holder which then emptied the contents onto me and the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bladder had not been emptied - and the aircraft had been in the hangar for 3 weeks!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, it was my job to clean up the mess - lots of french chalk as urine is very corrosive to airframes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radio also needed writing up so I tagged it as &quot;suspect urine ingress&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same radio came back to me with a tag attached saying (and this might work only for non-American English speakers) - &quot;are you taking the p*ss?&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yeuch.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2014-03-17T19:46:47.683" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2390" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T20:22:14.363" Score="19" Body="&lt;p&gt;Of course, in certain situations a plane &lt;em&gt;has&lt;/em&gt; to be painted white...or another colour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde had to be finished in a special, &lt;a href=&quot;http://www.speedbirds.pwp.blueyonder.co.uk/concfacts.htm&quot; rel=&quot;noreferrer&quot;&gt;highly reflective white paint&lt;/a&gt; to mitigate the extreme heating effects that friction caused at mach 2.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[It] reaches 127° C at the nose and trailing edge, but the special ‘high-reflectivity’ white paint helps reflect and radiate heat. Its reflectivity is 80 out of 100, compared to the rating of normal white paint of 45-50 out of 100, Concorde is re-painted every three years.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Conversely, the SR-71 Blackbird was painted matte black for almost exactly the same reason, plus some radar signature reduction.&lt;/p&gt;&#xA;" OwnerUserId="1563" LastEditorUserId="7670" LastEditDate="2016-03-22T18:05:40.943" LastActivityDate="2016-03-22T18:05:40.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2391" PostTypeId="2" ParentId="2135" CreationDate="2014-03-17T20:25:24.963" Score="3" Body="&lt;p&gt;To put wind speed in perspective (further to the previous remark that 150 km/h is not fast at altitude): The speed of the &lt;a href=&quot;http://www.skybrary.aero/index.php/Jet_Stream&quot; rel=&quot;nofollow&quot;&gt;Jet Stream&lt;/a&gt; is typically 100 kts (185.2 km/h) but can reach 200 kts (370.4 km/h) over North America and Europe in the winter. Speeds of 300 kts (555.6 km/h) are not unheard of, particularly over south-east Asia. Aircraft flying west-east will try to exploit the Jet Stream to increase ground speed and, similarly, aircraft flying East-West will plan to avoid the Jet Stream.&lt;/p&gt;&#xA;" OwnerUserId="1470" LastActivityDate="2014-03-17T20:25:24.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2392" PostTypeId="2" ParentId="2328" CreationDate="2014-03-17T21:38:08.770" Score="1" Body="&lt;p&gt;Depressurization leads not only to the lack of oxygen in the cabin (and cockpit), but likewise may lead to a dramatic drop in temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For altitudes above 38,000 - 65,000 feet, the outside temperature is roughly -70°F/-55°C.  Combined with data suggesting that at 40,000 feet a passenger sitting quietly would retain consciousness for only about 18 seconds with the loss of oxygen from depressurization (and thus presumably fewer seconds at 45,000 feet), it may only be a matter of seconds, not minutes, before everyone in the cabin would be dead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I don't know and wish I did know is whether the cabin and cockpit have separate pressurization systems.  I assume so.  This would make it even easier for a pilot to incapacitate/kill all crew and passengers. &lt;/p&gt;&#xA;" OwnerUserId="1568" LastEditorUserId="97" LastEditDate="2014-03-19T07:16:45.630" LastActivityDate="2014-03-19T07:16:45.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2394" PostTypeId="2" ParentId="2358" CreationDate="2014-03-17T22:53:16.717" Score="13" Body="&lt;p&gt;&lt;em&gt;Broadly&lt;/em&gt; the legal constructs that apply here are essentially the same as for sailing vessels - in other words when you're outside the jurisdiction of any given nation the laws of the country the vessel is registered in apply, and the captain is the one who makes the decisions.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;More specifically&lt;/em&gt; once you enter the airspace of a nation that nations laws also apply (the same as crossing the boundary from international waters to the territorial waters of a nation - by entering their territory you're obligated to abide by their laws).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If the above doesn't seem murky enough, it's because it actually gets a &lt;em&gt;lot&lt;/em&gt; more complicated than that when you start considering all the laws various countries may pass (and subsequently attempt to enforce).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider for example &lt;a href=&quot;http://www.justice.gov/usao/eousa/foia_reading_room/usam/title9/crm01405.htm&quot;&gt;The &quot;Special Aircraft Jurisdiction of the United States&quot;&lt;/a&gt; in which the US claims jurisdiction over any aircraft in our airspace, or any aircraft in flight which is &lt;em&gt;intending to land on our soil&lt;/em&gt; (as long as they actually &lt;em&gt;do&lt;/em&gt; land on our soil).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with most areas of international law going to far down this rabbit hole will likely lead to madness.&lt;br&gt;&#xA;For practical purposes you can assume that four bodies of law will govern every flight: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The laws of the country from which the aircraft is departing.&lt;/li&gt;&#xA;&lt;li&gt;The laws of any country whose airspace the aircraft transits, while in that airspace.&lt;/li&gt;&#xA;&lt;li&gt;The laws of the country in which the aircraft is landing.&lt;/li&gt;&#xA;&lt;li&gt;The laws of the country to which the aircraft is registered.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;...and if you can avoid breaking any laws in those 4 categories you'll be pretty well covered for most circumstances.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-17T22:53:16.717" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2395" PostTypeId="2" ParentId="2354" CreationDate="2014-03-17T23:34:03.310" Score="6" Body="&lt;p&gt;Apart from technical reasons, I am not really aware of, let me put it this way: &lt;strong&gt;Would you fly in a black plane?&lt;/strong&gt; Probably not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You associate colours with objects, feelings, situations etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;White can be trivially associated with sky, just like blue. I believe most airlines stick to these colours, since it helps associating the brand with sky. But the colours can have deeper meaning which is often used for marketing purposes. White is often associated with trust and perfection. Blue is associated with quality, security, trust or business. Notice many company logos are blue and white - Facebook, IBM, GE, Samsung, Hilton.&lt;/p&gt;&#xA;" OwnerUserId="1575" LastEditorUserId="1575" LastEditDate="2014-03-19T01:57:15.270" LastActivityDate="2014-03-19T01:57:15.270" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2396" PostTypeId="1" AcceptedAnswerId="2430" CreationDate="2014-03-18T01:36:21.503" Score="7" ViewCount="656" Body="&lt;p&gt;I was looking through my virtual radar logs one of the days and found this &quot;glitchy&quot; ADS-B behavior.  I am almost 100% sure that this is not due to my antenna or setup since two independent different radars confirmed this weird behavior from FlightRadar24.  Also A/C before and after this one did not exhibit this behavior.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Does anybody have any thoughts as to what may be happening???&lt;/li&gt;&#xA;&lt;li&gt;Why is the &quot;skew&quot; at seemingly same angle?  Is that anything?&lt;/li&gt;&#xA;&lt;li&gt;In light of MH370, does this happen often, how reliable is that GPS data?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Tail # N657UA&#xA;Boeing 767-300&#xA;Typical route between EGLL and KORD&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time of occurrence is approximately: 3/16/2014 6:09pm CST&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also verified FlightAware is ALSO showing the same weird glitch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See below &quot;yellow&quot; highlighted airplane:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/mFnFY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same A/C from FlightRadar24:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/wuiTp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to be related to THIS aircraft.  The explanations given (GPS-&gt;INS-&gt;GPS switching) still applies in my opinion, but wanted to give another screen shot.  Here it is today (3/30/2014) and again displaying this behavior - should their maintenance department be alerted to adjust their GPS antenna??&#xA;&lt;img src=&quot;https://i.imgur.com/0U8OJ15.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="795" LastEditDate="2014-03-30T16:13:55.947" LastActivityDate="2014-12-15T18:44:10.420" Title="Is this a glitchy ADS-B signal?" Tags="&lt;radar&gt;&lt;ads-b&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2014-03-20T07:31:29.297" ContentLicense="CC BY-SA 3.0" />
  <row Id="2397" PostTypeId="2" ParentId="2353" CreationDate="2014-03-18T02:50:06.467" Score="6" Body="&lt;h2&gt;1. Money&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Meals are available at different prices. Most US airlines know you aren't choosing them on the basis of cuisine and pick the lowest priced meal they can get away with. Other airlines eg Emirates, Singapore compete by offering high customer services and so invest more money in better food and service.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;2. Culture&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Airlines which are mostly flying a home market will adapt the food to the traditions of the country. EL-AL aren't going to be serving bacon cheese-burgers and Air India used to do very good veggie curries.&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="97" LastEditDate="2014-03-18T02:51:46.097" LastActivityDate="2014-03-18T02:51:46.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2399" PostTypeId="1" CreationDate="2014-03-18T06:02:14.210" Score="4" ViewCount="711" Body="&lt;p&gt;You are asked to fly a 91 owner trip to a destination. A 135 trip comes up after your owner flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does your 135 duty time start when company asked you to fly the 91 owner flight?    &lt;/p&gt;&#xA;" OwnerUserId="1585" LastEditorUserId="167" LastEditDate="2014-03-18T12:15:51.767" LastActivityDate="2014-03-18T12:16:04.223" Title="Does Part 135 duty time begin at the start of a part 91 owner flight which occurred immediately before?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2400" PostTypeId="2" ParentId="2382" CreationDate="2014-03-18T06:13:35.950" Score="3" Body="&lt;p&gt;On most commercial aircraft there is a circuit breaker for the cockpit voice recorder. The recorder can record communication in the cockpit for 30 minutes or up to two hours on later model aircraft. They are continuous loops which will record over the oldest previous recordings. Whenever any incident occurs during the operation of a flight, the circuit breaker is pulled to keep the pertinent cockpit conversation on record and not be recorded over. I am unaware of any such circuit for the flight data recorder.&lt;/p&gt;&#xA;" OwnerUserId="1584" LastActivityDate="2014-03-18T06:13:35.950" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2401" PostTypeId="2" ParentId="2347" CreationDate="2014-03-18T06:25:43.213" Score="1" Body="&lt;p&gt;There is only one pressurization system for the whole aircraft. The two outflow valves regulate the airflow moving through the cockpit and cabin respectively, the intake air comes from engine bleed air, which is quite hot, and is mixed with outside ambient air to regulate the temperature through two or more heat exchangers, depending on the make and size of the aircraft. If there were two pressurization systems, one for the cockpit and one for the cabin, there would have to be a pressure bulkhead between the cockpit and the cabin, and there isn't.&lt;/p&gt;&#xA;" OwnerUserId="1584" LastActivityDate="2014-03-18T06:25:43.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2402" PostTypeId="1" AcceptedAnswerId="2432" CreationDate="2014-03-18T06:42:41.517" Score="11" ViewCount="3173" Body="&lt;p&gt;Quoting from page 162 of the book &amp;quot;Fatal traps for helicopter pilots&amp;quot; by Greg Whyte:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Hydraulic jack stall (servo transparency) in (AS-350) helicopter is an aerodynamic phenomenon can occur when the helicopter is flown outside it is normal flight envelope and subjected to positive maneuvering (g-loading).&lt;/p&gt;&#xA;&lt;p&gt;It results in uncommanded aft and right cyclic and down-collective motion accompanied by pitch up and right roll of the helicopter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;My question:&lt;/p&gt;&#xA;&lt;p&gt;What is reason for uncommanded aft and right cyclic collective down pitch up and right roll?&lt;/p&gt;&#xA;" OwnerUserId="1057" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2021-05-24T06:31:37.147" Title="Why do hydraulic jack stalls result in pitch up and right roll?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2404" PostTypeId="1" AcceptedAnswerId="2439" CreationDate="2014-03-18T08:25:26.463" Score="11" ViewCount="4079" Body="&lt;p&gt;I enjoy tracking air traffic at my local KORD.  I listen on LiveATC and use my private virtual radar setup to get &quot;real-time&quot; traffic info.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand which instructions need to be read back by the pilots per &lt;a href=&quot;https://aviation.stackexchange.com/questions/279/which-atc-instructions-should-be-repeated-back-by-the-pilot&quot;&gt;this question&lt;/a&gt; however on more than one occasion I don't hear read back on critical vector info on departure, despite the visual confirmation of instruction (pilot making proper vector and speed adjustments).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tend to notice this with bigger birds (777,747,340), however smaller regional jets almost always promptly read back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there an alternative way of ATC instruction acknowledgement? (Other than read back?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it possible that the reply is somehow on a different frequency?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is this just a problem with LiveATC? (One theory is that A/C leaves receiver coverage area and that's why I don't hear reply, however on approach side much bigger distances are heard in my area)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Thank you&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I did verify that indeed the aircraft that I don't hear read back from receives special departure frequency by tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once tower clears aircraft for take off and hands them off to departure controller they use &quot;departure&quot; frequency to read back instructions.  It is typically different from standard departure frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing that is not clear is if there is any rhyme or reason for which aircraft gets this special departure frequency and which doesn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As pointed out in the question for some reason mostly it is &quot;big&quot; aircraft that gets this preferential treatment, but I am not 100% sure why.&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-03-19T01:30:25.927" Title="Why do I not always hear ATC read back by pilots (on required instructions)?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2405" PostTypeId="1" CreationDate="2014-03-18T08:46:59.863" Score="8" ViewCount="11462" Body="&lt;p&gt;I want to know how aileron reversal takes place when control reversal velocity is higher than divergence speed  and operating speed is in between them (for conventional wing)&lt;/p&gt;&#xA;" OwnerUserId="1592" LastEditorUserId="167" LastEditDate="2014-03-18T12:13:12.397" LastActivityDate="2019-04-15T06:00:53.710" Title="How does aileron reversal work?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2406" PostTypeId="1" AcceptedAnswerId="2418" CreationDate="2014-03-18T10:36:15.520" Score="5" ViewCount="948" Body="&lt;p&gt;Will the above mentioned equipment still work and transmit data/location information if an explosion occurs inside the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1598" LastEditorUserId="64" LastEditDate="2014-03-18T22:07:09.330" LastActivityDate="2019-04-17T21:46:22.990" Title="What happens to the transponder, FDR and CVR in case of an explosion?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;transponder&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2407" PostTypeId="2" ParentId="2406" CreationDate="2014-03-18T10:45:03.643" Score="9" Body="&lt;p&gt;FDR and CVR don't transmit anything they just record data onto a magnetic tape or in a solid state drive, when the plane crashes/explodes they become just part of the debris and wait until they get found. The boxes are rated to survive nearly any feasible aircraft crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The special case is if they get submerged, then the &lt;a href=&quot;http://en.wikipedia.org/wiki/Underwater_locator_beacon&quot;&gt;attached locator beacon&lt;/a&gt; will activate and send out pings for at least 30 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The transponder will likely not survive and it needs power to work either way.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-03-18T12:30:01.183" LastActivityDate="2014-03-18T12:30:01.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2408" PostTypeId="1" CreationDate="2014-03-18T11:25:24.197" Score="3" ViewCount="297" Body="&lt;p&gt;A plane has sensors that should transmit data back somewhere when it hits water correct? Is it possible that these can be turned off/damaged?&lt;/p&gt;&#xA;" OwnerUserId="1600" LastEditorUserId="64" LastEditDate="2014-03-19T01:41:13.323" LastActivityDate="2014-03-21T00:34:55.317" Title="Is it possible for the sensors which determine when an aircraft has landed in water to become damaged?" Tags="&lt;accidents&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2409" PostTypeId="2" ParentId="2381" CreationDate="2014-03-18T11:44:47.887" Score="0" Body="&lt;p&gt;I think this is more possible in theory than in fact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One radar station has given blind spots, but most nations use a whole array of stations.  So if you were not seen on one sensor you'd probably be seen on another.  Plus shadowing behind another jet would likely put you in a zone of dangerous wake turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the ocean it's easier not to be noticed since ATC radar stations are built on land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from sensors noticing you dilligence is required by those who monitor the sensors.  Seems like that might have been absent on the Malaysian jet, if it actually diverted course radically and crossed the Malaysian peninsula as is being suggested in the news.&lt;/p&gt;&#xA;" OwnerUserId="1601" LastActivityDate="2014-03-18T11:44:47.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2410" PostTypeId="2" ParentId="2408" CreationDate="2014-03-18T11:44:56.400" Score="4" Body="&lt;p&gt;Yes, the component in question is called the &lt;a href=&quot;http://en.wikipedia.org/wiki/Underwater_locator_beacon&quot; rel=&quot;nofollow&quot;&gt;Underwater Locator Beacon&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not foolproof. To disable them manually you need physical access to the black boxes, which are located in the tail section of the plane.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="774" LastEditDate="2014-03-18T13:08:56.243" LastActivityDate="2014-03-18T13:08:56.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2411" PostTypeId="2" ParentId="2381" CreationDate="2014-03-18T12:05:12.197" Score="2" Body="&lt;p&gt;Theoretically possible once you get close enough. In fact military aircraft do it all the time, making a group of smaller aircraft look like a single larger one.&lt;br/&gt;&#xA;But there's a catch, getting close enough in the first place, and without being noticed.&lt;br/&gt;&#xA;The crew and passengers of the other airliner would notice a T7 flying in close formation, and even if they didn't see it, they would notice the buffeting and certainly the proximity alarm on the other airliner would notify the crew, who'd notify ATC, who'd send in fighter aircraft to see what the heck was going on.&lt;br/&gt;&#xA;And don't forget that it takes rather serious training to get aircraft to fly that close, and close coordination between the aircraft to retain that formation and not crash into one another. All of which would not be in place in your scenario.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So no, it's just another conspiracy theory dreamed up by people who've seen aircraft with crews trained for it fly in close formation at an airshow and didn't know what is involved, just like the idea that the T7 would have flown at wavetop level to avoid radio contact, or diving and weaving through the mountains just over the ground.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-18T12:05:12.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2412" PostTypeId="2" ParentId="2399" CreationDate="2014-03-18T12:16:04.223" Score="3" Body="&lt;p&gt;Absolutely, 135.267 (d) requires you to have 10 hours of rest within the 24 hour period preceding the completion of every 135 flight, and if the 91 flight is for the same company then it is not considered rest. Duty time starts when you are required to do anything for the company, and for a typical flight it starts when you arrive at the airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information on rest, see &lt;a href=&quot;https://aviation.stackexchange.com/q/533/69&quot;&gt;this question&lt;/a&gt; and answer. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-03-18T12:16:04.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2413" PostTypeId="2" ParentId="1572" CreationDate="2014-03-18T12:56:40.883" Score="1" Body="&lt;p&gt;Theoretically you can fly a Boeing 747 on a Private Pilots Licence as long as you have the relevant type ratings. If you are flying passengers for profit you will then require at least a Commercial Pilots Licence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern day training courses which prepare you to be the first officer or co-pilot as it were, tend to result in you holding a frozen ATPL, ie, you have done all the exams and you're now hour building in order to qualify for the licence. You will also likely have completed a Multi-Crew Co-operation course of some description, obtained your jet rating and hold any relevant Instrument Ratings. It probably depends on which provider you were choosing to apply for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Ah, my apologies, this post was in relation to European (EASA) guidelines (more specifically in the UK really).&lt;/p&gt;&#xA;" OwnerUserId="1594" LastActivityDate="2014-03-18T12:56:40.883" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2414" PostTypeId="2" ParentId="2269" CreationDate="2014-03-18T13:06:12.093" Score="17" Body="&lt;p&gt;Not to take away from already great answer provided.  In my experience the jumping behavior you are describing in Flightradar24 is due to MLAT triangulation that is used to establish approximate location rather than absolute (using GPS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older planes transmit a SUBSET of ads-b data, which does not include aircraft location.  So FR24 knows that there is an aircraft in the air, but doesn't know its location.  This is where multilateration (triangulation really) comes into play.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a few (minimum of 4) receivers available AROUND the aircraft that are tuned precisely to the same clock, you can measure how long that same ads-b signal reaches all 4 receivers from which approximate location can be determined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In FR24 you can verify which of the &quot;jumpy&quot; planes are being tracked by MLAT setup by looking at &quot;radar&quot; that is tracking it.  If MLAT is used you will see &quot;T-MLAT&quot; as the source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you indeed see jumpy behavior on the planes that are tracked by &quot;T-###&quot; or &quot;F-###&quot; sources then I would agree with already posted answer by DeltaLima&lt;/p&gt;&#xA;" OwnerUserId="795" LastActivityDate="2014-03-18T13:06:12.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2416" PostTypeId="2" ParentId="2126" CreationDate="2014-03-18T13:10:23.533" Score="1" Body="&lt;p&gt;Automation is not always the best idea. There was an incident at an airshow where the pilot was doing a low, slow flyby in a commercial jet (I believe it was one of the newer Airbus models), and he applied full power to climb away, and the computer decided that it was an incorrect control movement. Needless to say, the aircraft crashed.&lt;/p&gt;&#xA;" OwnerUserId="1594" LastEditorUserId="97" LastEditDate="2014-03-21T05:27:59.027" LastActivityDate="2014-03-21T05:27:59.027" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2417" PostTypeId="1" AcceptedAnswerId="2424" CreationDate="2014-03-18T13:42:27.257" Score="11" ViewCount="444" Body="&lt;p&gt;Spencer Suderman recently did a world record 81-turn inverted flat spin, and dropped over 21 thousand feet while doing so. The entire thing is &lt;a href=&quot;http://youtu.be/dL63avj-BCU&quot;&gt;documented on youtube&lt;/a&gt;. The spin starts at &lt;a href=&quot;http://youtu.be/dL63avj-BCU?t=2m50s&quot;&gt;3 minutes into the clip&lt;/a&gt;. Looking at the footage, in the beginning of the spin, and also (although to a lesser extent) at the end of the spin, the altimeter is unwinding very unevenly, being almost steady for a second and then quickly unwinding 3-500 feet before steadying (or actually increasing the first couple of turns) for another second. Why is that? It seems unreasonable to me that it would actually be leveling out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth noting that in the middle of descent, when spin is perfectly flat, it's unwinding evenly.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-05-03T21:03:53.633" Title="Why is the altimeter unwinding unevenely during a spin?" Tags="&lt;aerodynamics&gt;&lt;aerobatics&gt;&lt;spins&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2418" PostTypeId="2" ParentId="2406" CreationDate="2014-03-18T14:04:14.090" Score="10" Body="&lt;p&gt;As ratchetfreak noted, the recorders don't transmit data, attached to them is a location beacon that operates for up to 30 days.&lt;/p&gt;&#xA;&lt;p&gt;This location beacon isn't always successful in enabling searchers to find the recorders. In the case of AF447, it took two years before a search located the aircraft debris field on the sea floor and recovered it's recorders.&lt;/p&gt;&#xA;&lt;p&gt;As for withstanding the stresses of an explosion, it obviously depends on the strength of the explosion and it's location in the aircraft. In the case of Pan Am 103, destroyed in flight by explosives, the recorders were recovered and data extracted.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A DFDR must obviously have a high degree of ‘crashworthiness.’ The first units were required to withstand a momentary shock force of 1,000gs, the latest test standards now call for a test to &lt;strong&gt;3,400gs&lt;/strong&gt; for a duration of 6.5 milliseconds. The units also have to withstand a static crushing force at all of its six axis points of an applied load force of 5,000lbs for 5 minutes on each axis. Third, it must withstand a 500lbs piercing force test conducted by dropping it onto a ¼ inch steel pin from 10 feet. Lastly it must withstand a 1,100°C fire test for 60 minutes, and a 260°C oven test for 10 hours.&lt;/p&gt;&#xA;&lt;p&gt;It is also required that these units are mounted within the tail area of an aircraft, away from the potential crushing force of any engines mounted nearby. The DFDR must be watertight to a depth of 20,000 feet in sea water, and survive at this depth for 30 days - and it must be fitted with an underwater locator beacon which will act like a sonar transmitter, by ‘pinging’ a signal through the medium of water that it might be laying in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.avbuyer.com/articles/detail.asp?id=1858&quot; rel=&quot;noreferrer&quot;&gt;http://www.avbuyer.com/articles/detail.asp?id=1858&lt;/a&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1G is the force you feel on your feet standing up.&lt;/li&gt;&#xA;&lt;li&gt;12G is the most a fighter-jet pilot normally experiences in combat.&lt;/li&gt;&#xA;&lt;li&gt;16G sustained for 1 minute will kill you.&lt;/li&gt;&#xA;&lt;li&gt;25G for an less than a second will hospitalize a fit &lt;a href=&quot;http://www.dailymail.co.uk/sport/formulaone/article-2487112/Fernando-Alonso-taken-hospital-25G-impact--double-G-forces-experienced-fighter-jet-pilot.html&quot; rel=&quot;noreferrer&quot;&gt;racing car driver&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;350G results in &lt;a href=&quot;https://www.sto.nato.int/publications/STO%20Educational%20Notes/RTO-EN-HFM-113/EN-HFM-113-03.pdf&quot; rel=&quot;noreferrer&quot;&gt;total body fragmentation&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;In a &lt;a href=&quot;http://www.channel4.com/news/once-in-a-generation-plane-crash-study&quot; rel=&quot;noreferrer&quot;&gt;727 crash landing&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Impact forces at the front of the plane peaked at 12 G (12 times the force of gravity), in the centre the force was less, 8 G, at the rear it was 6 G, half that at the front and no greater than being hit in a fairground bumper car.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qqOHt.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;In a &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880000639.pdf&quot; rel=&quot;noreferrer&quot;&gt;720 crash&lt;/a&gt;,&#xA;the maximum force was 14 G vertically for 0.8 seconds&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1rVFv.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;This F4 phantom striking a concrete block at 480 MPH produced average peak forces of &lt;a href=&quot;http://www.iasmirt.org/transactions/10/DC_250400.pdf&quot; rel=&quot;noreferrer&quot;&gt;less than 60 G (see fig 7)&lt;/a&gt;. The most solid elements (the engines) experienced forces of up to 700 G (fig 11).&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ufyjd.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;3400G is therefore a lot.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-04-17T21:46:22.990" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="2419" PostTypeId="1" CreationDate="2014-03-18T14:17:53.587" Score="8" ViewCount="4476" Body="&lt;p&gt;What are the &lt;strong&gt;steps needed to become a pilot that can transport skydivers&lt;/strong&gt;?&lt;br&gt;&#xA;I'm more specifically interested in the situation in Europe, France.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would expect lessons / certifications, then more certification to accept passengers, then more certifications to be allowed to carry skydivers and let them jump. Also, medical examination, books, insurance, fees...  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How much would it cost?&lt;/strong&gt;&lt;br&gt;&#xA;I'm more interested in the money amount spent usually observed than the theoretical price. I have a day job so I won't be able to easily spend all days of the week at the airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How long should I expect until I'm certificated?&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, &lt;strong&gt;how often should I fly to stay current.&lt;/strong&gt; &#xA;Obviously, there is the issue of practicing enough to be safe and the legal requirements to be allowed to fly with passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also expect to be required to be certificated with a specific level for the skydiving. Bonus points if you can answer that too.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have seen this question about &lt;a href=&quot;https://aviation.stackexchange.com/questions/627/how-much-generally-speaking-does-it-cost-to-learn-how-to-fly&quot;&gt;how much it cost to learn to fly&lt;/a&gt;, but it is less specific than my case. Still, many interesting points in its answers.&lt;/p&gt;&#xA;" OwnerUserId="1599" LastEditorUserId="14661" LastEditDate="2019-04-18T04:24:34.697" LastActivityDate="2019-04-18T04:24:34.697" Title="What should I do to become a pilot for skydivers, in France?" Tags="&lt;flight-training&gt;&lt;pilot-certification&gt;&lt;easa-regulations&gt;&lt;skydiving&gt;&lt;france&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="2420" PostTypeId="2" ParentId="2319" CreationDate="2014-03-18T15:05:03.790" Score="1" Body="&lt;p&gt;These interesting posts do not answer the question of how many pings sent from the satelite&#xA;were actually answered from the aircraft?  The publshed data only talks about the last ping. The system is said to be automated with the satelite sending queries on a periodic basis, reportedly hourly.  If each of these were in fact answered by the aircraft this would produce eight sets of data, each of which could generate an arc&#xA;delimiting possible position....basically eight concentric circles centered on the satelite&#xA;position, similar to the one published.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the above posts points out that such successive data would quickly reveal the aircraft's velocity vector directly toward or away from the satelite position...given the known signal times and the distance between the concentric arcs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would seem reasonable that one could make some assumptions about the magnitude of overall veloctiy vector...it should be a reasonable efficient cruising speed...say 400 mph...or a reasonable range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If 8 data sets were generated one or more of the earlier sets should be close to a time&#xA;when the aircraft's position was known from radar.  Starting from that time and position one could use the actual total speed to determine distance traveled  - which would locate the two possible positions (north and south) on the next arc in temporal sequence, i.e. two possible specific locations with speed and heading at that time.  One then repeats this procedure from those positions to the next arc actual in time sequence, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end this would produce two points, north and south, on the final (published) arc,&#xA;representing a possible northern and possible southern location as well an approximation&#xA;of the aircraft's actual tracks - either northern or southern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These plotted tracks could be useful, especially in the northern case, to identify approximately when the aircraft might have entered a specific country's radar range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Addendum:  This is really a question of velocity vectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between any two arcs, assuming you have a position to start with, you can easily determine &#xA;the aircraft velocity vector directly toward or away from the location of the satelite projected on the earth's surface.  This velocity is a known quantity - it the distance between the two arcs divided by the time elapsed.  It is true we do not know actual speed but we could assume a cruising speed...an efficient cruising speed for this aircraft is apparently 560 mph at 35,000 feet.  So we know the magnitude of this vector (our assumption) but not the direction...northly or southerly  Given the time lapse involved one can calculate the distance the aircraft would fly in this time.  Set a drafting compass to that magnitude, mark a circle from the last known or calculated location and the two points where that circle intersects the next salelite arc are the putative new locations - one north and one south. In the end this should produce north and south limited portions of the final arc as more likely search areas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted ... there could well be an error in cruising speed assumption.  One could assume an upper and lower speed and produce a range of possible locations at each arc.  As one looks at a whole series of arcs it may also be possible to adjust the assumed cruise speed and to see any changes in course direction.  If the aircarft had a distant goal it would seem important to choose an efficient cruise velocity to conserve fuel. &lt;/p&gt;&#xA;" OwnerUserId="1610" LastEditorUserId="1610" LastEditDate="2014-03-18T19:09:57.303" LastActivityDate="2014-03-18T19:09:57.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2422" PostTypeId="1" AcceptedAnswerId="2534" CreationDate="2014-03-18T16:05:15.760" Score="12" ViewCount="5616" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot;&gt;14 CFR 1.1&lt;/a&gt; includes the following definitions related to crewmembers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Crewmember&lt;/em&gt; means a person assigned to perform duty in an aircraft during flight time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Flightcrew member&lt;/em&gt; means a pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some of the regulations (although not all instances) also refer to a &lt;em&gt;required crewmember&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotaly I have heard of people being assigned as a crewmember on the spot so that they could fly in an aircraft that is limited to &quot;crewmembers only&quot; (i.e. some world war two era aircraft, etc.) by saying something like:     &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;If the normal gear extension fails during this flight, then you will be responsible to pull this emergency handle over here.  Okay, got it?&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure whether or not that would technically qualify someone as a crewmember, so are there any legal interpretations from the FAA or any guidance on what actually does qualify someone as a crewmember?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-21T15:29:47.823" Title="What are the legal requirements to be a &quot;crewmember&quot;?" Tags="&lt;faa-regulations&gt;&lt;crew&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2423" PostTypeId="2" ParentId="2419" CreationDate="2014-03-18T16:10:36.683" Score="1" Body="&lt;p&gt;You'll want to start by getting a private pilots license and then go on to get a commercial pilot's license. An instrument rating isn't required, but would be beneficial.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A private pilot's license (PPL) will cost you around \$8,000, commercial license (CPL) will be an additional \$17,000, and instrument ratings around \$6,000. One common method for gaining hours/pay is to become a certified flight instructor (CFI); this may cost you an additional \$7,000. Call you local flight school and ask for exact prices, but plan to spend 10% to 20% more than the listed price because you'll need additional hours to the bare minimum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting a PPL and CPL will allow you to fly for skydiving operations. Federal regulations (14 CFR Part 119) describe the certification requirements for air carriers and commercial operators, but exempts skydiving flights operating within 25 miles of the departure airport. As a result, skydiving flights are conducted in accordance with 14 CFR Part 91 and 14 CFR Part 105.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR Part 91&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Allows skydivers to use the floor of an aircraft as a seat, provided that there is a seat belt for each skydiver to use.&lt;/li&gt;&#xA;  &lt;li&gt;Requires every reserve parachute on board to have been packed within the preceding 120 days.&lt;/li&gt;&#xA;  &lt;li&gt;Requires a transponder for flight at or above 10,000 MSL, an altitude commonly exceeded by most jump planes. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;14 CFR Part 105&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Requires skydivers to observe visual flight rules (VFR) conditions. Below 10,000 feet, the pilot must have three miles of visibility and at least 500 feet below, 1,000 feet above, and 2,000 feet horizontally from a cloud. At and above 10,000 feet, the rules require five miles of visibility and 1,000 feet below, 1,000 feet above, and one mile horizontally.&lt;/li&gt;&#xA;  &lt;li&gt;Holds the pilot responsible for jumps that create a hazard to air traffic or persons, or property on the ground.&lt;/li&gt;&#xA;  &lt;li&gt;Requires prior permission from an airport manager before jumping over or onto an airport.&lt;/li&gt;&#xA;  &lt;li&gt;Requires ATC authorization when jumping into Class A, B, C, or D airspace. Prior to jumping into Class E and G airspace, the appropriate ATC facility must simply be notified beforehand.&lt;/li&gt;&#xA;  &lt;li&gt;Requires radio communications with the appropriate ATC facility at least 5 minutes prior to the jump. This requirement is primarily intended to allow the jump pilot to receive information from ATC about known traffic in the area. It is best to make the call soon after takeoff for radar coverage. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Additional Information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=7721&quot; rel=&quot;nofollow&quot;&gt;http://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=7721&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States#Commercial_pilot&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States#Commercial_pilot&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1611" LastEditorUserId="72" LastEditDate="2014-04-21T07:12:31.207" LastActivityDate="2014-04-21T07:12:31.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2424" PostTypeId="2" ParentId="2417" CreationDate="2014-03-18T16:16:02.787" Score="11" Body="&lt;p&gt;The altimeter works by measurements of the pressure in undisturbed air, also called static pressure. A static port is placed, usually on the side of the hull, perpendicular to the airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a spin, the airflow will not flow evenly past the static port, but will occasionally flow directly onto the static port. This will cause a rise in measured pressure, leading the altimeter to believe it is lower than it actually is. This cause fluctuations in the indicated altitude. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-03-18T16:16:02.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2425" PostTypeId="2" ParentId="2360" CreationDate="2014-03-18T16:32:33.513" Score="4" Body="&lt;p&gt;For a text book overview: &lt;a href=&quot;http://www.desktop.aero/appliedaero/potential3d/FSW.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.desktop.aero/appliedaero/potential3d/FSW.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the Hansa Jet actually was a production airliner using the forward swept wing, and 2 glider types that i regulalrly flew also had forward swept wings (for visibility reasons: Schleicher Ka7 and Ka13).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ryZj3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1614" LastActivityDate="2014-03-18T16:32:33.513" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2426" PostTypeId="2" ParentId="2354" CreationDate="2014-03-18T16:46:14.403" Score="10" Body="&lt;p&gt;I work for a printing company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think of this - why everything is printed mostly in black ink? why not navy blue, or dark hunter green?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because black is a stock color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer stocks it, and uses it left and right.&#xA;Most other colors have to be a special order - this comes with increased costs, lead times and paint expiration. If you did not use all of it, paint does expire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the printer-happy community let me remind you that painting a jet is not like printing a page where three base inks are used to create a perception of color.&#xA;Paint of any color has to be manufactured separately. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I think that from a manufacturing standpoint it is just so much cheaper to use stock white paint.&lt;/p&gt;&#xA;" OwnerUserId="1615" LastEditorUserId="97" LastEditDate="2014-03-18T21:34:13.893" LastActivityDate="2014-03-18T21:34:13.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2428" PostTypeId="1" AcceptedAnswerId="2431" CreationDate="2014-03-18T17:28:11.673" Score="11" ViewCount="5828" Body="&lt;p&gt;A disadvantage of the analogue radio&lt;sup&gt;1&lt;/sup&gt; used for communication is that it does not receive when it transmits. Everybody is trained to wait until the frequency is quiet before starting to talk, but it's still possible that two stations will start talking at the same time, in which case everybody else will hear an unintelligible mess but the two talking will not be aware of it. The station who talks longer won't be aware at all and if they talk for similar time, neither may be aware.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I would like to know is how humans deal with the problem and whether there is any specific guideline for resolving these conflicts.&lt;br&gt;&#xA;It seems like if the controller just says &quot;calling centre, say again&quot; the two may just both start talking past each other again.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sup&gt;1&lt;/sup&gt;&amp;nbsp;Just like any other shared frequency radio, but digital systems seem to have more options to handle it, especially for the relatively low bandwidth requirement of voice communication.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="1696" LastEditDate="2015-02-15T18:10:39.453" LastActivityDate="2015-02-15T18:10:39.453" Title="How do pilots/controllers deal with overlapping transmissions on the radio?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2429" PostTypeId="2" ParentId="2428" CreationDate="2014-03-18T17:44:13.370" Score="2" Body="&lt;p&gt;It isn't really an analog vs. digital problem. Even WiFi connections have the same problem, and they rely on built in collision avoidance techniques to make it work. But it turns out that what humans do is pretty similar to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_detection&quot; rel=&quot;nofollow&quot;&gt;collision avoidance techniques used in wireless communications&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, two people try to contact the tower at the same time and step on each other's transmission. So the tower doesn't respond to either. Both people try again after some amount of time. As long as there is just a tiny amount of difference in the amount of time they wait, one of the retransmissions will come first, and the other person will wait.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In uncontrolled airspace, when using the advisory frequency things aren't as simple, but in practice at least one of the people will stop talking first and realize they were colliding with the other and repeat their transmission. The bottom line is that I don't think this is a problem, except when the airspace is very busy, and in that case a different technology is unlikely to make much of a difference.&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2014-03-18T17:44:13.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2430" PostTypeId="2" ParentId="2396" CreationDate="2014-03-18T18:46:06.980" Score="5" Body="&lt;p&gt;This is a classic example of fallback to INS. Most of the track data is coming from GPS. For some reason the GPS signal is lost momentarily causing a fall back to INS. The INS is offset by about 1km to the Northeast, which appears as a jump. Next position report is from the GPS again, in line with the original track. This happens several times. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the transmitted data these spikes will be flagged as data of low integrity. This allows for filtering them out.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-15T18:44:10.420" LastActivityDate="2014-12-15T18:44:10.420" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2431" PostTypeId="2" ParentId="2428" CreationDate="2014-03-18T19:38:06.350" Score="14" Body="&lt;p&gt;Well in regard to &quot;How are these situations resolved?&quot; you've already answered your own question in a way: the intended recipient responds with something like &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/B.HTM&quot;&gt;&quot;Blocked&quot;&lt;/a&gt; or &quot;Calling center, say again.&quot; (If they are expecting to hear from a specific aircraft they'll often respond with &quot;N12345, say again.&quot;, and if the frequency congestion is really bad controllers may add &quot;All other aircraft standby&quot;).&lt;br&gt;&#xA;As kevin42 pointed out this is very similar to what digital &lt;a href=&quot;http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_detection&quot;&gt;CSMA/CD&lt;/a&gt; systems do - they detect a collision (&quot;Blocked&quot;), wait a while, and try their transmission again.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a practical matter, two-way voice communication over the radio is &lt;em&gt;possible&lt;/em&gt;, but difficult: for example a discrete &quot;uplink&quot; and &quot;downlink&quot; frequency as you have with some radio systems would be impractical in the sort of mesh topology that you have with aviation radio (you could implement it for a single air-to-ground pair trivially, but aviation radios are also used for air-to-air communication, and it's important that pilots hear what's going on as this enables them to build a mental picture of the airspace, as well as ensure that they're not blocking other pilot's transmissions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding analog-vs-digital, the traditional AM radio used in aircraft has one major advantage over its digital counterparts: when two digital signals overlap the result is garbage -- you can't recover any of the information. When two analog AM signals overlap you get heterodyning (the two signals mix, and your receiver pipes that mix into your ears).&lt;br&gt;&#xA;The resulting mixed signal sounds &lt;strong&gt;&lt;em&gt;AWFUL&lt;/em&gt;&lt;/strong&gt;, there's an ear-bleeding squeal from the out-of-phase carriers and the voice modulations combine to a garbled mess much of the time, but with experience you can usually pick out one of the communications (particularly if you're close to one of the transmitters, where it will overpower the more distant signal).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ability to step on a transmission as described above this can be useful: Instructions have been issued over a &quot;stuck mic&quot; before to get other aircraft off the frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a similar vein, if you have an emergency you probably aren't going to listen before you talk - you're going to key the mic with your mayday and even if the controller misses half of what you're saying under the heterodyne noise they'll know there's an emergency when they hear the other half of your transmission and tell everyone else to standby while they talk to you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both of those situations a digital system implementing CSMA/CD would detect that the frequency was in use and not transmit (and if were a digital system and transmitted anyway both digital signals would be garbled and unusable).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-18T19:53:43.117" LastActivityDate="2014-03-18T19:53:43.117" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2432" PostTypeId="2" ParentId="2402" CreationDate="2014-03-18T20:53:54.470" Score="9" Body="&lt;p&gt;A moderately quick search reveals a &lt;a href=&quot;http://www.pprune.org/rotorheads/297744-hydraulic-lock-jack-stall.html&quot; rel=&quot;noreferrer&quot;&gt;few&lt;/a&gt; &lt;a href=&quot;http://www.pprune.org/rotorheads/254165-jackstall-what-any-experiences.html&quot; rel=&quot;noreferrer&quot;&gt;pprune&lt;/a&gt; &lt;a href=&quot;http://www.pprune.org/rotorheads/225261-dauphin-pole-video.html&quot; rel=&quot;noreferrer&quot;&gt;threads&lt;/a&gt; and an &lt;a href=&quot;http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20011025X02148&amp;amp;ntsbno=FTW02FA017&amp;amp;akey=1&quot; rel=&quot;noreferrer&quot;&gt;accident report&lt;/a&gt;. From these I understood that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hydraulic jack stall occurs when the aerodynamic force on the rotor blades exceeds the force the hydraulic actuator can apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actuators are controlling pitch of rotor blades and are applying force to keep the angle of attack high. When the angle of attack gets too high the blades stall which is associated with change in centre of lift creating a moment trying to rotate the blade to lower angle of attack, strong enough to overpower the actuator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The right pitch moment is because the retreating blades have higher angle of attack and approach stall earlier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The forward pitch moment is when the stall happens in higher G manoeuvre where the helicopter is pitching up and thus the blades in front are running at higher angle of attack and approach stall earlier. If the stall happens due to overspeed, the pitch moment will be back instead. In either case it will be opposite to the selected cyclic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The down collective moment is because the angle of attack decreases on the forward (or backward) and right blades, but does not increase on the other ones, so the total lift is reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The behaviour can be considered a good thing as it prevents aerodynamic stall from fully developing. The effect is also similar to what would happen if the actuators were more powerful and aerodynamic stall did fully develop. It can however be more surprising for the pilot since it may happen before vibrations that normally indicate incipient aerodynamic stall. The condition is self-correcting in that the reduction in pitch causes reduction in G loading and thus reduction of the aerodynamic forces, but the drop in performance can obviously be a problem if it happens too low.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-03-18T21:28:55.180" LastActivityDate="2014-03-18T21:28:55.180" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2433" PostTypeId="1" AcceptedAnswerId="2440" CreationDate="2014-03-18T22:37:30.883" Score="7" ViewCount="660" Body="&lt;p&gt;I am building my own ATC simulator and for that purpose I need to include several instrument procedures. I have a problem with &lt;a href=&quot;http://www.hcaa.gr/hellasais/aipdocs/eaip/pdf/AD2/AD2-LGAV/AD2-LGAV-IAC-10.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;that particular one&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FTT9v.jpg&quot; alt=&quot;AD2-LGAV-IAC-10 AIP&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My problem is on KEA transition, the leg between &quot;RDL 256 KEA&quot; and &quot;RDL 192 ATV&quot; how should the transition be encoded in terms of ARINC-424 path terminator sequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically it's the turn from the one leg to the other that bothers me: &quot;RDL 256 KEA&quot; seems to terminate on either 27 DME KEA or RDL 187 ATV. But then what? There is a 20 DME ATV on the next leg that spoils everything. CD (or Course to DME) is not a specific route over the ground so the previous turn won't be able to intercept it. I could either omit the CD part or insert another CR (course to radial) before the CD leg but then I'm not doing what the map says, I improvise. So my question is am I conceiving this wrong, or the IAC is ambiguous in this particular point?&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2019-11-08T00:35:54.467" LastActivityDate="2020-01-13T04:14:32.003" Title="How do you encode a radial to radial turn in ARINC-424?" Tags="&lt;aeronautical-charts&gt;&lt;instrument-procedures&gt;&lt;iaps&gt;&lt;arinc-424&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2435" PostTypeId="2" ParentId="2354" CreationDate="2014-03-18T23:08:07.947" Score="5" Body="&lt;p&gt;White paint won't absorb as much heat as black or another color, imagine walking on bare blacktop vs. the white painted line.  I found &lt;a href=&quot;http://scienceline.ucsb.edu/getkey.php?key=3873&quot;&gt;this&lt;/a&gt; article to save me the explanation.  The black paint absorbs the entire spectrum of photons, whereas the white reflects most of the  photons.  When a photon is absorbed, its energy is absorbed (a photon is energy) and the heat of the plane increases.&lt;/p&gt;&#xA;" OwnerUserId="1623" LastEditorUserId="1623" LastEditDate="2014-03-20T00:27:33.467" LastActivityDate="2014-03-20T00:27:33.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2436" PostTypeId="2" ParentId="2404" CreationDate="2014-03-19T00:57:15.980" Score="5" Body="&lt;p&gt;At my airport, KCOS, tower has split frequencies for the east and west runways. 90 percent of the time both are handled by the same controller. They transmit and receive on both frequencies, but you are only listening to one.&lt;/p&gt;&#xA;" OwnerUserId="757" LastActivityDate="2014-03-19T00:57:15.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2437" PostTypeId="1" AcceptedAnswerId="2465" CreationDate="2014-03-19T01:10:05.467" Score="13" ViewCount="24338" Body="&lt;p&gt;Is it possible that a commercial airliner could hit the ocean surface at such an angle that it made a deep dive intact, got filled with water, sank, and got stuck in mud at the floor of the ocean?&lt;/p&gt;&#xA;" OwnerUserId="1626" LastEditorUserId="64" LastEditDate="2014-04-04T21:22:16.360" LastActivityDate="2014-04-14T06:43:13.477" Title="Can a commercial airliner sink to the bottom of the ocean?" Tags="&lt;airliner&gt;&lt;accidents&gt;&lt;ditching&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2438" PostTypeId="2" ParentId="2437" CreationDate="2014-03-19T01:23:16.160" Score="10" Body="&lt;p&gt;Hitting water at speed is a lot like hitting concrete (try experimenting with different positions hitting the water off a high diving board&amp;mdash;some will hurt). Aircraft are simply not designed to withstand the sudden forces introduced upon impact with water, no matter the angle. If an aircraft were to hit the water at high speed, the relatively flimsy structures of the aircraft would shatter, disintegrate, and completely lose structural integrity.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-19T01:23:16.160" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2439" PostTypeId="2" ParentId="2404" CreationDate="2014-03-19T01:30:25.927" Score="11" Body="&lt;p&gt;The O'Hare Eight Departure is the only departure procedure out of ORD.  This is what it looks like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pV3Xg.png&quot; alt=&quot;O&amp;#39;Hare Eight Departure Chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that there are three departure control frequencies:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Chicago Dep Con West: 125.4&lt;/li&gt;&#xA;&lt;li&gt;Chicago Dep Con East/North: 125.0&lt;/li&gt;&#xA;&lt;li&gt;Chicago Dep Con South: 126.635&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Airplanes are usually given the frequency appropriate for the sector that their first departure fix is located in.  If they are very busy, each sector will have its own departure controller and they will be talking to different people.  If it isn't as busy, they pilots will still be talking on their individual frequencies, but one controller may be listening to and transmitting on two or all three frequencies at once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if a particular aircraft is cleared over POLO VOR (due west of ORD) they will be given a departure frequency of 125.4 as part of their clearance.  Let's say that the traffic is slow and only one controller is being used to cover all three frequencies.  If you are listening to the East/North frequency on 125.0, you will hear the departure controller issue a clearance to the aircraft, but never hear the response because the aircraft is transmitting on 125.4.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-19T01:30:25.927" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2440" PostTypeId="2" ParentId="2433" CreationDate="2014-03-19T01:45:58.177" Score="8" Body="&lt;p&gt;So you fly the KEA transition like this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Track RDL 265 KEA until crossing RDL 187 ATV or 27 DME KEA&lt;/li&gt;&#xA;&lt;li&gt;Start a right turn and intercept RDL 192 ATV&lt;/li&gt;&#xA;&lt;li&gt;Fly RDL192 until intercepting final&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As egid said, RDL 187 ATV is a &lt;a href=&quot;http://www.pilotoutlook.com/instrument_flying/intercepting_lead_radials&quot; rel=&quot;nofollow&quot;&gt;lead radial&lt;/a&gt; which is a radial used only to tell you when to start a turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as 20 DME ATV, it is actually only used for the PELAG transition so you can ignore it in this case.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-19T12:51:50.210" LastActivityDate="2014-03-19T12:51:50.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2441" PostTypeId="2" ParentId="2328" CreationDate="2014-03-19T02:36:37.173" Score="2" Body="&lt;p&gt;The answer is yes: if one of the pilots needed to use the restroom, regulations require the other pilot to put on his O2 mask while the other pilot is away. Once outside the cockpit, the other pilot could lock the door and the other pilot out. Then he could turn everything off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also since it was at about 1:30am, most passengers would be trying to sleep in their chairs; additionally the masks that drop only have enough O2 to last while the aircraft descends to a lower/safer altitude &amp;mdash; so if the plane maintained altitude, there would only be 5-10 minutes of O2 and everyone would pass out and eventually die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless it landed on smooth water, like the miracle on the Hudson, the plane's ELT (Emergency Locator Transmitter) would go off and the crash site would be pinpointed by satellites within seconds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So therefore one of two things happened:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It landed on water softly and is now at bottom of ocean, or;&lt;/li&gt;&#xA;&lt;li&gt;It landed safely on land because there was no ELT signal.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1628" LastEditorUserId="17262" LastEditDate="2019-01-17T16:37:41.303" LastActivityDate="2019-01-17T16:37:41.303" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="2442" PostTypeId="2" ParentId="2422" CreationDate="2014-03-19T03:33:21.333" Score="2" Body="&lt;p&gt;I'm not aware of a glossary anywhere that defines all the possible types of required crew, but I can name some.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The important thing is that the definition of &quot;required crew&quot; varies based on the requirements of the flight, not the certification of the aircraft.  Required crew are also those crew required to safely operate the aircraft under the conditions of the flight.  For instance, a photographer (who has no other duties) is not &quot;required&quot; crew even if the purpose of the flight is to conduct photography.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First you have the crew required by FAA regulations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the pilot, and co-pilot if required.  Along the same lines, an instructor, safety pilot, or examiner would also be considered required crew if required by the flight (if the pilot is not rated in the aircraft, or is wearing a view limiter, etc.)  Also, relief pilots, if the duration of the flight is long enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigators and flight engineers, although few aircraft still need engineers and navigators are basically obsolete now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight attendants, if the aircraft carries more than nine passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is carrying hazardous materials, then a cargo specialist might be required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the definition of &quot;required&quot; and &quot;crew&quot; gets a little sloppy is when it comes to experimental aircraft.  If the aircraft is something like a new airliner prototype, then the engineers will have produced a mountain of paperwork detailing exactly what the crewmembers are and what they need to do.  But for amateur-built or ex-military aircraft, &quot;required&quot; is a bit more nebulous.  One particular case is the Commemorative Air Force's B-29, which the CAF likes to fly with extra engineering crew that the USAF didn't use when they operated it:&#xA;&lt;a href=&quot;http://www.avweb.com/news/pelican/182150-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;http://www.avweb.com/news/pelican/182150-1.html?redirected=1&lt;/a&gt;&#xA;The FAA isn't always thrilled about this, even where there's an engineering justification for it.  An ad-hoc &quot;emergency gear lever crewman&quot; on what amounts to a pleasure ride would be one of those wink-and-nudge cases that, if the flight actually experienced a problem, would probably incur some ill will from the FAA or NTSB investigators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally, I've also heard of amateur-built aircraft taking up two crew on testing flights, one to fly the plane and another as, essentially, a flight engineer, especially if the engine being used is not an ordinary Lycoming/Continental.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, regulations restrict the use of the jump seats only to approved persons, such as a relief pilot, company check pilot, or someone else who &quot;belongs there.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1027" LastActivityDate="2014-03-19T03:33:21.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2443" PostTypeId="1" AcceptedAnswerId="26393" CreationDate="2014-03-19T04:22:28.790" Score="22" ViewCount="4670" Body="&lt;p&gt;There've been a lot of questions lately about tracking aircraft, and after a conversation with a friend of a friend I started wondering:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Could a &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Distress_radiobeacon&quot; rel=&quot;noreferrer&quot;&gt;PLB or EPIRB&lt;/a&gt; carried by a passenger or crew member aid in locating a downed or missing airliner?&lt;/strong&gt; There are a dozen or so brands out there, most using similar technology, like this ACR ARTEX unit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rJruu.jpg&quot; alt=&quot;ResQLink PLB with GPS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I'm well aware of the FAA and FCC regulations about electronic devices in flight, and that's not what I'm interested in. I also realize that airliners already carry an ELT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a paranoid passenger brought one on board, &lt;strong&gt;would these devices function at all from inside an airliner cabin?&lt;/strong&gt; Some feed GPS location data to a 406MHz locator beacon, and those would potentially be less useful (as they'd have to be at hand and probably triggered manually. Others, like the Spot GPS tracker, have the ability to upload GPS track data on the fly to satellite communications networks such as Iridium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm personally skeptical, given that GPS generally needs a clear view of the sky and that a fuselage seems likely to block or reduce a 406Mhz ELT signal, but I'm curious to know if there's any information out there.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-19T16:39:31.940" LastActivityDate="2016-03-29T08:19:57.293" Title="Could a Personal Locator Beacon or EPIRB carried by a passenger aid in locating a downed airliner?" Tags="&lt;safety&gt;&lt;avionics&gt;&lt;passenger&gt;&lt;electronics&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2445" PostTypeId="2" ParentId="2419" CreationDate="2014-03-19T05:18:05.447" Score="4" Body="&lt;p&gt;Short answer: you need a commercial pilot's license. The drop zone will provide the extra training, it takes about a day (I worked at a skydive center for 10 years)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, since you seem to not have any kind of pilot's license right now (or you would know this already) I will add that it isn't a full-time job at any except the busiest drop zones. Our pilots usually worked for a couple of years to build time and then went on to other aviation jobs. During those 1-2 years they had other income - flying for us was mainly a way to log flying hours without having to rent aircraft. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-03-19T05:18:05.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2446" PostTypeId="2" ParentId="2365" CreationDate="2014-03-19T05:26:34.773" Score="9" Body="&lt;p&gt;The marketing term is &quot;loss leader&quot; - you lose money on the advertised product but make more money on other things. In this case fees and other things the customer might buy ( checked bags, water ) after we get them in the door (website).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your grocery store does this weekly. For example: 2 litre Coca-cola $0.49 deals.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-03-19T05:26:34.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2447" PostTypeId="2" ParentId="2328" CreationDate="2014-03-19T06:46:11.043" Score="5" Body="&lt;p&gt;Very simple operation and you don't need to be at 41,000 feet to do it. Anything above about 21,000 feet and you die in a few minutes; you just fall asleep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are really paying attention, you would first notice your fingernails (under them) will turn blue due to a lack of oxygen first. A few giggles perhaps, then you'd pass out and DIE. Quite painlessly actually.&lt;/p&gt;&#xA;" OwnerUserId="1634" LastEditorUserId="97" LastEditDate="2014-03-19T07:13:54.333" LastActivityDate="2014-03-19T07:13:54.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2448" PostTypeId="5" CreationDate="2014-03-19T07:34:13.373" Score="0" Body="&lt;p&gt;Use  &lt;a href=&quot;/questions/tagged/efb&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;efb&amp;#39;&quot; rel=&quot;tag&quot;&gt;efb&lt;/a&gt; instead for cockpit device usage in an electronic flight bag.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-19T07:55:08.820" LastActivityDate="2014-03-19T07:55:08.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2449" PostTypeId="4" CreationDate="2014-03-19T07:34:13.373" Score="0" Body="Electronic devices including cell phones, iPads and laptops." OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2015-01-27T20:15:19.463" LastActivityDate="2015-01-27T20:15:19.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2450" PostTypeId="2" ParentId="170" CreationDate="2014-03-19T07:53:32.663" Score="15" Body="&lt;p&gt;Rogue wing panels flying off and puncturing hoses is the latest thing &lt;a href=&quot;http://sploid.gizmodo.com/huge-part-of-a-delta-airliners-wing-breaks-off-at-take-1545521564&quot; rel=&quot;noreferrer&quot;&gt;to make headlines&lt;/a&gt;...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UiYho.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Definitely tell the cabin crew if you see anything like that ;)&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-03-19T07:53:32.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2451" PostTypeId="2" ParentId="2443" CreationDate="2014-03-19T07:54:08.733" Score="-11" Body="&lt;p&gt;No, they couldn't. EPIRB beacons have a very short range, by the time you get a signal you'd also have a signal from the beacons in for example the flight data recorder.&lt;br/&gt;&#xA;You seem (like a lot of people) under the impression that GPS receivers send their location to the satellite which then sends it somewhere to a data center where it can be retrieved. This is incorrect. The device only reads from the satellite network, calculating its position based on signals from the satellites. And it then uses either a short range radio transmitter or a cellphone network to transmit that location to interested parties. But of course in the middle of nowhere there are no cellphone towers and a short range radio doesn't help if the nearest recipient is far away.&lt;br/&gt;&#xA;On a ski slope that's no problem, as you're in civilisation and not far from help. In the middle of the ocean it's of no use whatsoever.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-19T07:54:08.733" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2452" PostTypeId="1" AcceptedAnswerId="2453" CreationDate="2014-03-19T09:03:59.940" Score="3" ViewCount="1766" Body="&lt;p&gt;Are 40 hours of flight really enough to gain experience to fly a small private plane alone anywhere? The rules state so but from experience off you pilots, is it really enough or should be more hours be clocked with another experienced pilot next to you before venturing out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today I had my first flight on a 152 from Dar es Salaam International Airport, and the area is quite busy. There were bigger aircraft taking off and approaching and  many other taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting an inexperienced pilot that has barely 40 hours in an environment like this could cause serious problems even though he has gone through courses and exams. As you know one thing is theory and another is practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would appreciate some clarification.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="97" LastEditDate="2014-03-21T03:04:28.850" LastActivityDate="2014-03-21T03:04:28.850" Title="PPL 40 hours requirement, are you really ready?" Tags="&lt;flight-training&gt;&lt;ppl&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2014-03-19T13:47:59.123" ContentLicense="CC BY-SA 3.0" />
  <row Id="2453" PostTypeId="2" ParentId="2452" CreationDate="2014-03-19T10:04:09.627" Score="7" Body="&lt;p&gt;With the caveat that this is based on experience mostly in the US:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most people take 60-80 hours to get their private pilot license:&#xA;&lt;a href=&quot;http://www.aviationcareerguide.com/private_pilot_license.asp&quot;&gt;http://www.aviationcareerguide.com/private_pilot_license.asp&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The harder you work, and the more often you fly, the fewer hours you'll need.  The average hours are inflated somewhat by the many pilots who run out of time or money partway through, have to stop, and must then relearn what they forgot when they start back up again.  If you have the time, money, and dedication to fly two or three times a week, you'll get your license in fewer hours (not to mention fewer days!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't worry too much about the safety of it though.  Your instructor won't let you take the exam, and your examiner won't pass you, if you're not ready.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as flying out of a major airport, my opinion is that it doesn't much affect the time or amount of experience required.  In the US, it's usually more expensive because costs are higher at large airports, but you may not have the option.  For most pilots, the hardest part of flying into a large airport is getting lost on the taxiways - but it will not take long to learn your way around your home airport.  If anything, it will make you a better pilot.  Today much of flying is dealing with controllers and airspace rules, and if you learn at a major airport, you'll have plenty of practice with that.&lt;/p&gt;&#xA;" OwnerUserId="1027" LastActivityDate="2014-03-19T10:04:09.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2454" PostTypeId="1" CreationDate="2014-03-19T10:06:32.393" Score="30" ViewCount="26643" Body="&lt;p&gt;On a commercial airliner, there is a hole in one of the layer of the passenger windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See here:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V0suq.jpg&quot; alt=&quot;Airplane window&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and here:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XByjt.jpg&quot; alt=&quot;Another airplane window&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or in more detail:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MaFKf.png&quot; alt=&quot;Zoom on hole in airplane window&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you explain the physical reasons for this design choice?&lt;/p&gt;&#xA;" OwnerUserId="1599" LastEditorUserId="15982" LastEditDate="2017-06-10T00:18:13.447" LastActivityDate="2021-01-11T20:36:51.187" Title="Why is there a hole in one of the layer of an airplane's windows?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;cabin-pressure&gt;&lt;windows&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2455" PostTypeId="2" ParentId="2454" CreationDate="2014-03-19T10:13:09.713" Score="26" Body="&lt;p&gt;Aircraft windows are multiple layers thick. The side facing the passengers is just a plastic sheet, since they wouldn't want the passengers scratching up the actual expensive glass window. Beyond the inner pane there are two actual structural window panes. The outer one is normally the one bearing the load, while the inner one serves as a backup.&lt;/p&gt;&#xA;&lt;p&gt;However, since pressure changes in the cabin during the flight, it's also necessary to &lt;strong&gt;equalize the pressure between the window panes&lt;/strong&gt;, and hence the little hole. A hole of that size would not jeopardize pressurization even if the outer pane blew out. Note the label &amp;quot;Breather Hole&amp;quot; in the diagram below.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dL9tw.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;There is a rubber seal around the outside of the two panes so it would be a bit of a pain to open a hole to cavity from the side. Apart from that, the windows are pretty tight together and by keeping it where it is there is nothing in the vicinity such as dust that could gradually be pulled in.&lt;/p&gt;&#xA;&lt;p&gt;Since the air in between the panes is colder, it's not unusual to see ice crystals forming around the hole as the more humid cabin air enters the cavity.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dyKy5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dyKy5.jpg&quot; alt=&quot;787window&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://www.gentex.com/sites/default/files/imagecache/default/wysiwyg_imageupload/air_diagram_1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;gentex.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;787 Window&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;This diagram includes the electric shade system of the 787 which is fairly similar. Since the two outermost panes carry no structural purpose you can just have them equalize air as you please.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2021-01-11T20:36:51.187" LastActivityDate="2021-01-11T20:36:51.187" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="2456" PostTypeId="1" AcceptedAnswerId="2459" CreationDate="2014-03-19T10:42:50.580" Score="36" ViewCount="19606" Body="&lt;p&gt;I was flying on an A320 (equipped with sharklets) the other day, and I found these hooks on the wing's surface:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1ZIHH.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the single hooked attachment is outside the wing's &quot;DO NOT WALK OUTSIDE THIS AREA&quot; line. What are these hooks used for? Why is the single hooked attachment outside the &quot;safe&quot; walking area line?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="97" LastEditDate="2014-03-21T02:57:41.843" LastActivityDate="2017-10-08T13:34:35.957" Title="What are these hooks on the A320's wing used for?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;airbus-a320&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2457" PostTypeId="2" ParentId="2456" CreationDate="2014-03-19T10:50:45.417" Score="13" Body="&lt;p&gt;The inner ones are mounting points for evacuation slides and/or a rope handrail since the wing is likely to be slippery and wet. Several aircraft including the A320 and B737 have additional overwing life rafts when ditching. You clip in a rope either at these points or in a hook at the window, throw it overboard, and give it a sharp tug to inflate. Joyous passengers will then board the life raft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://farm4.staticflickr.com/3813/12581689695_50d267937e_h.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;https://www.flickr.com/photos/king_aevil/12581689695&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The outer one works as a harness securing points for the maintenance guys working on the wing, but I guess this could be used for the first purpose as well if you would want to gather everybody around one wing or something.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-02T12:42:04.457" LastActivityDate="2015-06-02T12:42:04.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2458" PostTypeId="1" AcceptedAnswerId="2462" CreationDate="2014-03-19T13:24:06.210" Score="14" ViewCount="2969" Body="&lt;p&gt;KORD airport for instance charges domestic vs international arrivals differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could see that this may have something to do with imports/taxes/tariffs etc, but why are the landing fees measured in \$ per 1,000lbs?&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="64" LastEditDate="2015-10-30T02:51:55.537" LastActivityDate="2015-10-30T02:51:55.537" Title="Why are landing fees at large airports based on weight?" Tags="&lt;airport&gt;&lt;landing-fees&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2459" PostTypeId="2" ParentId="2456" CreationDate="2014-03-19T13:37:37.343" Score="32" Body="&lt;p&gt;In the event of a water evacuation, there is a line associated with each overwing exit that is extended, and clips to that yellow bracket, as a guide to get everyone out on the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Overwing_exits#Use_in_a_ditching&quot;&gt;Wikipedia&lt;/a&gt;, these are for overwing exits.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The use of overwing exits in a ditching varies from airline to&#xA;  airline. On aircraft fitted with overwing exits, there is typically a&#xA;  raised escape rope bracket (about a third of the way from the door)&#xA;  attached to the wing's upper surface and typically painted yellow.&#xA;  This is accompanied by an escape rope found in the frame of the exit&#xA;  after opening the hatch. Once this rope is attached to the escape rope&#xA;  bracket, it will aid passenger evacuation onto the wing to await&#xA;  rescue or to enter the water (depending on the airline's procedures).&#xA;  On aircraft with life rafts to be launched via the overwing exit, the&#xA;  wing will be used to provide a boarding platform onto the life raft.&#xA;  On certain regional aircraft, the overwing exits are the only escape&#xA;  route in the event of a ditching.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-03-19T13:52:58.323" LastActivityDate="2014-03-19T13:52:58.323" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2460" PostTypeId="2" ParentId="2443" CreationDate="2014-03-19T14:21:56.693" Score="9" Body="&lt;p&gt;I have a &lt;a href=&quot;http://www.findmespot.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SPOT Beacon&lt;/a&gt; that I use for occasional adventures: mostly flying small planes and kayaking.  But its small enough I generally carry it with me when I fly commercial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5c75R.jpg&quot; alt=&quot;Spot Becaon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because it connects to satellites, no one needs to be nearby to &quot;hear&quot; it.  I can press the SOS button most anyplace in the world and summon help.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some remote parts of the ocean where there is not good satellite coverage, (see the &lt;a href=&quot;http://www.findmespot.com/en/index.php?cid=108&quot; rel=&quot;nofollow noreferrer&quot;&gt;coverage map&lt;/a&gt;), but generally it may help in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if such a device would work from inside a commercial airliner.&#xA;I do know I've been able to get GPS signals by pressing a GPS receiver up against a cabin window, but it is slow to acquire the GPS lock.  I don't know if it could transmit to the satellite network through the cabin window.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-03-19T14:34:43.923" LastActivityDate="2014-03-19T14:34:43.923" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2461" PostTypeId="2" ParentId="2456" CreationDate="2014-03-19T14:28:38.800" Score="22" Body="&lt;p&gt;Likely they are tethering points for emergency exit ropes. The Boeing 737-800 has the same type of hooks. See top row from the water evacuation procedures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZS0bG.jpg&quot; alt=&quot;Boeing 737-800 evacuation procedures&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://flight72.storenvy.com/collections/132463-safety-cards/products/120964-delta-airlines-boeing-737-800-safety-card&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1636" LastEditorUserId="65" LastEditDate="2015-07-02T14:37:41.183" LastActivityDate="2015-07-02T14:37:41.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2462" PostTypeId="2" ParentId="2458" CreationDate="2014-03-19T14:48:27.870" Score="13" Body="&lt;p&gt;From Anne Graham's book, &lt;a href=&quot;http://books.google.es/books?id=7AkXgynWQDYC&quot;&gt;Managing Airports&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This charging mechanism uses the ‘ability to pay’ principles, since&#xA;  airlines using larger aircraft are in a better position to pay higher&#xA;  charges. Some costs such as runway wear and tear do increase with&#xA;  weight and also larger aircraft require vortex separations, which can&#xA;  reduce the number of aircraft movements during a certain period.&#xA;  Overall, however, there is not a strong relationship between aircraft&#xA;  weight and airfield cost. A flat rate landing charge for all aircraft&#xA;  types may be more appropriate, particularly at congested airports.&#xA;  This is because the cost of occupying the congested runway is movement&#xA;  related and independent of aircraft size. Each aircraft movement will&#xA;  consume the same resource.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1128" LastActivityDate="2014-03-19T14:48:27.870" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2463" PostTypeId="2" ParentId="2220" CreationDate="2014-03-19T15:32:04.500" Score="6" Body="&lt;p&gt;Assuming the question was referring to the US airport market, where indeed a big chunk of the airport fees are indeed taxes, here's their composition according to &lt;a href=&quot;http://www.airlines.org/Pages/Government-Imposed-Taxes-on-Air-Transportation.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airlines for America&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qEOFj.png&quot; alt=&quot;Special (Commercial/General) Aviation Taxes&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1128" LastActivityDate="2014-03-19T15:32:04.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2464" PostTypeId="1" AcceptedAnswerId="2468" CreationDate="2014-03-19T15:52:14.830" Score="7" ViewCount="912" Body="&lt;p&gt;Are the effects created by turbulence on the aircraft different when the aircraft is banking or in level flight? By logic I'd say yes but I would like some technical and practical explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When in level flight I can imagine that the aircraft is moved laterally or vertically. What happens when these forces are applied from turbulence when  banking? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the consequences of turbulence having the aircraft banked, for example, on the lift produced by the wings?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-04-25T00:09:05.767" LastActivityDate="2015-04-25T00:09:05.767" Title="Do the effects of turbulence change when banking/turning compared to level flight?" Tags="&lt;aerodynamics&gt;&lt;turbulence&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2465" PostTypeId="2" ParentId="2437" CreationDate="2014-03-19T16:01:36.547" Score="18" Body="&lt;p&gt;&lt;strong&gt;Can a large modern jet airliner plunge intact underwater from flight?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large airliners are not desgned for this and are not even strong enough to make a landing on water in less than perfect conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y9LoF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;E.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961&quot; rel=&quot;noreferrer&quot;&gt;961&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;striking the surface at a larger angle would certainly lead to widespread disintegration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is it possible for a large modern jet airliner to sink intact?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes (as near as makes no difference)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all large aircraft impacting the sea surface in an emergency or uncontrolled will break up immediately and catastrophically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One notable exception was &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;US1549&lt;/a&gt;, an A320, which was landed on water without breaking up. It was described as &quot;still virtually intact though partially submerged and slowly sinking&quot;. The left engine detached and sank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/m6hja.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a controlled landing on water is possible under extremely favourable circumstances. It would then be possible for the aircraft to sink in more-or-less one piece without creating a large amount of floating debris.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-03-19T16:13:29.220" LastActivityDate="2014-03-19T16:13:29.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2466" PostTypeId="1" AcceptedAnswerId="2467" CreationDate="2014-03-19T16:03:45.177" Score="7" ViewCount="486" Body="&lt;p&gt;I am reading in the news that the MH370 flight changed its course by &quot;Computer entry&quot; and that it was programmed into the computer at least 12 minutes before the last voice contact with the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can they know that the change in the computer was done 12 minutes before (while the plane was still flying as on the original course)? And how do they know it was done in the computer, rather than the pilot steering manually?&lt;/p&gt;&#xA;" OwnerUserId="1527" LastEditorUserId="22550" LastEditDate="2018-11-22T14:59:31.873" LastActivityDate="2018-11-22T14:59:31.873" Title="How does an aircraft report crew programming of the FMS to the ground?" Tags="&lt;navigation&gt;&lt;mh370-incident&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2018-11-22T15:09:08.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="2467" PostTypeId="2" ParentId="2466" CreationDate="2014-03-19T16:21:05.933" Score="7" Body="&lt;p&gt;The aircraft's Flight Management System (FMS) can be loaded with software that periodically sends position reports and flight tracking data to ground stations via ACARS.  If the particular software in use sends the full flight plan or at least the next few fixes periodically with estimated times, this would expose any changes in the flight plan to the dispatch office.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident flight in question had its ACARS turned off at some point and the &quot;12 minute&quot; figure is probably derived from the time between the last ACARS message being received and the radar observed turn off course initiated.   They would not be able to know exactly when the buttons on the FMS were pressed, but they could narrow the time down to a range when information changed between two automated reports sent via ACARS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Relevant chronology:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;01:07 final ACARS transmission&#xA;01:19 final voice communication&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Interval: 12 minutes.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="1289" LastEditDate="2014-03-19T17:34:15.303" LastActivityDate="2014-03-19T17:34:15.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2468" PostTypeId="2" ParentId="2464" CreationDate="2014-03-19T16:52:05.623" Score="7" Body="&lt;p&gt;Turbulence affects aircraft in the same way whether it is banked or not.  The difference however would be the end result of the turbulence.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if an aircraft were to encounter turbulence strong enough to roll the aircraft 20 degrees to the right, the end results would be a 20 degree bank if starting from level, but 45 degrees of bank if they were already in a 25 degree banked turn.  If this were to happen it puts them closer to their stall speed because of the higher bank angle, and if they were already going slow and the airplane is at a low altitude, it could be a problem.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fortunately, most turbulence strong enough to cause this while at low altitude is caused by the wake turbulence of other aircraft or microbursts, and we have pretty good procedures in place to keep it from being a problem these days.  If they aren't at a low altitude it matters even less because there is altitude for the aircraft to recover even if it does get into an unusual attitude.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-19T16:52:05.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2469" PostTypeId="1" AcceptedAnswerId="2471" CreationDate="2014-03-19T19:13:40.630" Score="13" ViewCount="9230" Body="&lt;p&gt;As far as I understand glider pilots like to look out for &lt;a href=&quot;http://en.wikipedia.org/wiki/Thermal&quot;&gt;thermals&lt;/a&gt;. I assume that when you are &lt;em&gt;in&lt;/em&gt; one, you can perceive that and you can make roughly sure to stay in it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what if you're not in a thermal? How do you look for one? Are these methods (like finding a cumulus?) significantly/statistically more efficient than just randomly browsing? Or is it mostly a question of luck?&lt;/p&gt;&#xA;" OwnerUserId="1379" LastEditorUserId="97" LastEditDate="2014-03-21T02:56:17.167" LastActivityDate="2014-03-21T03:12:31.723" Title="How are thermals found?" Tags="&lt;weather&gt;&lt;glider&gt;&lt;thermals&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2470" PostTypeId="2" ParentId="2469" CreationDate="2014-03-19T19:38:37.887" Score="3" Body="&lt;p&gt;the wiki article you linked say the following&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Thermals are often indicated by &lt;strong&gt;the presence of visible cumulus clouds at the apex of the thermal&lt;/strong&gt;. When a steady wind is present, thermals and their respective cumulus clouds can align in rows oriented with wind direction, sometimes referred to as &quot;cloud streets&quot; by soaring and glider pilots. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LWuSE.jpg&quot; alt=&quot;enter image description here&quot;&gt;(&lt;a href=&quot;http://www-ee.stanford.edu/~hellman/soaring.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source the next linked article&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;in absence of humid air (a blue sky) you can still find thermals by the techniques in &lt;a href=&quot;http://www-ee.stanford.edu/~hellman/soaring.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the air is very dry or the lift doesn't go high enough, lift does&#xA;  not generate clouds to act as markers. On such &quot;blue days&quot; (i.e., the&#xA;  sky is only blue, no white), you use other techniques:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&quot;House thermals&quot; are locations that frequently produce thermals. Most local pilots know the location of these faithful life savers, use&#xA;  them, and will share the knowledge with visitors or new comers.&lt;/li&gt;&#xA;  &lt;li&gt;Soaring birds have an uncanny ability to find thermals. If you see a soaring bird, following it will usually lead you to lift. If the&#xA;  bird leaves a thermal, follow it. It probably senses an even stronger&#xA;  thermal nearby. We don't know how birds find thermals, but they are&#xA;  better at it than any human or instrument we have yet devised.&lt;/li&gt;&#xA;  &lt;li&gt;Look for other sailplanes that are climbing. I emphasize the last part because several glider pilots often land in the same farmer's&#xA;  field. When they discuss what went wrong, each will often say, &quot;Well,&#xA;  I saw you circling so I figured there must be lift.&quot;&lt;/li&gt;&#xA;  &lt;li&gt;Look for dust devils &lt;em&gt;[mini sand tornado]&lt;/em&gt;. The lift can extend well above the top of the visible portion.&lt;/li&gt;&#xA;  &lt;li&gt;Look for topographic features that are likely to trigger thermals. In addition to those enumerated earlier, rocky slopes facing&#xA;  the sun, steep canyons, mountain peaks or passes, dark cirques facing&#xA;  the sun, and airports (lots of asphalt to soak up the sun's energy)&#xA;  are good examples.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-03-19T19:45:42.913" LastActivityDate="2014-03-19T19:45:42.913" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2471" PostTypeId="2" ParentId="2469" CreationDate="2014-03-19T19:39:47.920" Score="8" Body="&lt;p&gt;There are a few different things that you can look for, and to some degree it is trial and error as well.  Gliders will have an instrument that measures vertical speed so that they can tell &quot;how good&quot; a thermal is as well (a variometer or a Vertical Speed Indicator(VSI)).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the things to look for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Color variation on the ground because the difference in the amount of heat absorbed by the ground varies based on the color/composition.  The hotter area will cause the air to rise (hot air rises) and will create a thermal.  I.e. A dark colored area surrounded by a light colored area or vice-versa such as a parking lot with fields around it.&lt;/li&gt;&#xA;&lt;li&gt;Birds circling in an area because they tend to circle in thermals.&lt;/li&gt;&#xA;&lt;li&gt;Certain types of cloud formations that can indicate lift.&lt;/li&gt;&#xA;&lt;li&gt;Other gliders!  :-)&lt;/li&gt;&#xA;&lt;li&gt;If the wind is blowing across a mountain ridge or other large structure, the wind has nowhere to go but up so is also a good place to look for lift as well.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here is an example showing how some of the thermals form and how the wind affects them.  Notice also how once the air has been lifted to the point where it cools below the dewpoint that a cloud will form:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.genosplace.org/sailplaneweb/thermals3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UbwPm.jpg&quot; alt=&quot;Thermal Formation&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is another showing how terrain can cause lift:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dartmoorgliding.co.uk/assets/images/autogen/a_image002.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0bnsQ.jpg&quot; alt=&quot;Thermal Formation 2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-21T03:12:31.723" LastActivityDate="2014-03-21T03:12:31.723" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2472" PostTypeId="1" AcceptedAnswerId="2516" CreationDate="2014-03-19T20:51:55.570" Score="38" ViewCount="15432" Body="&lt;p&gt;I am reading &lt;a href=&quot;http://www.nytimes.com/interactive/2014/03/17/world/asia/search-for-flight-370.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; article on the NY Times, where they show two possible flight paths of the missing flight MH370 in the South Indian Ocean:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vn9LF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering how they can come up with such specific paths, when the only information we have are those two arcs (those arcs are not paths, rather the last satellite ping happened somewhere on the arc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can anybody create a computer model with just this information? Or does it mean that the modelers have more information available than the general public?&lt;/p&gt;&#xA;" OwnerUserId="1527" LastEditorUserId="19" LastEditDate="2016-07-05T09:40:36.627" LastActivityDate="2016-07-05T09:40:36.627" Title="How can a computer model yield two possible flight paths of MH370 in South Indian Ocean?" Tags="&lt;accidents&gt;&lt;mh370-incident&gt;&lt;search-and-rescue&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="2473" PostTypeId="2" ParentId="2472" CreationDate="2014-03-19T21:14:15.680" Score="20" Body="&lt;p&gt;The &quot;related article&quot; specified in your link has this to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Searching one possible flight path, Australia said it would focus its&#xA;  efforts in a specific stretch of the southern Indian Ocean, using&#xA;  computer models of the plane’s possible flight path that take into&#xA;  account undisclosed satellite data, wind conditions and ocean currents&#xA;  and some assumptions about how fast it was flying and how much fuel it&#xA;  had left.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, apparently they have more information than the general public does.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-19T21:14:15.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2474" PostTypeId="2" ParentId="2472" CreationDate="2014-03-19T21:14:39.163" Score="8" Body="&lt;p&gt;My personal guess: I think what they've done is to start a line where from where the&#xA;   plane was last known, and then intersected it with the arc where the&#xA;   distance would have been correct at cruise speed with reference to the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Example with just some values. Since the arc radius and time was known, one would be able to draw a line which would show a constant speed. If it was not a constant speed, the line would have to bend left/right to account for it, which does not appear to be the case in the provided image.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qy6KE.jpg&quot; alt=&quot;satellite example&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is based upon the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;'A signal was sent out every hour'. In other words, they got several data points.&lt;/li&gt;&#xA;&lt;li&gt;Based upon that, they would have points for the arc radius at set times. &lt;/li&gt;&#xA;&lt;li&gt;They might assume that the aircraft has a constant speed. Because of this, they should see if the data points lie on the a straight time, since the only variable is the distance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm pretty sure that the two lines is based upon the fact that they know the uncertainty at the final position, and in my opinion it suggests that the aircraft flew a constant course from the last known radar fix where it originates.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-19T22:50:39.203" LastActivityDate="2014-03-19T22:50:39.203" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2475" PostTypeId="2" ParentId="2405" CreationDate="2014-03-19T21:51:43.173" Score="10" Body="&lt;p&gt;Control reversal speed is &lt;em&gt;way lower than divergence speed&lt;/em&gt;. It may actually be lower than operating speed for some aircraft, which is why they have inboard ailerons/flaperons and/or use spoilers (that don't suffer control reversal) for roll control at high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Control reversal (at high speed; there is also control reversal at stall, which is different) occurs because the force generated by ailerons twists the wing sufficiently so that the aileron starts to act more like a trim tab. For that the wing has to flex, but it does not have to flutter at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilers act closer to the wing mid-chord, so they don't twist it much and thus don't suffer reversal. In fact they twist the wing a bit, because pre-stall lift acts more forward than post-stall lift, but this twists the wing forward and thus further reduces the lift, so still no control reversal.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="21091" LastEditDate="2017-05-08T05:58:02.400" LastActivityDate="2017-05-08T05:58:02.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2476" PostTypeId="1" AcceptedAnswerId="2477" CreationDate="2014-03-19T21:53:47.077" Score="16" ViewCount="2977" Body="&lt;p&gt;The G1000 has a feature where it can put up a winds aloft arrow/speed in the PFD.  I've been sort of wondering how exactly this is determined.  My guess is that the aircraft (or the G1000) knows your airspeed via the pitot/static system and heading via the fluxgate/mag compass.  Then, it uses your GPS position to figure out where you should be every X seconds given the airspeed and heading.  Any difference must be attributable to winds aloft.  Does this make sense?&lt;/p&gt;&#xA;" OwnerUserId="162" LastEditorUserId="162" LastEditDate="2014-03-19T22:14:24.677" LastActivityDate="2014-03-20T02:24:54.870" Title="How does an aircraft derive winds aloft on its own?" Tags="&lt;avionics&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2477" PostTypeId="2" ParentId="2476" CreationDate="2014-03-19T22:11:42.913" Score="12" Body="&lt;p&gt;Yes, you are correct. You need three pieces of information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;airspeed&lt;/li&gt;&#xA;&lt;li&gt;true compass heading (considering magnetic variation)&lt;/li&gt;&#xA;&lt;li&gt;multiple absolute position fixes (eg. from gps)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The aircraft heading has to be measured by a compass within the aircraft (it can't be derived from the gps track), and the gps position can be used to look up the local magnetic variation. The difference between the speed/heading and the ground track (in straight and level flight, anyway) is attributable to winds aloft.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="675" LastEditDate="2014-03-20T00:50:25.367" LastActivityDate="2014-03-20T00:50:25.367" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2478" PostTypeId="2" ParentId="2405" CreationDate="2014-03-20T01:06:58.343" Score="11" Body="&lt;p&gt;As I understand it, aileron reversal can occur in two regimes of flight, high speed and near stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Near stall, the wing is very near it's critical angle of attack. When the pilot inputs let's say a left turn, the right aileron will deflect downward. This downward deflection increases the AOA of the outboard portion of the right wing such that the lift generated by that outboard portion is lower (drag higher as well) than the lift generated on the opposite wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can kind-of visualize this by thinking of a wing operating on the backside of the lift curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aileron reversal at high speed, (again, as I understand it) can occur when the wing isn't stiff enough tortionally to prevent twisting about the aircraft's lateral axis when a control input is made. Some old warplanes had this characteristic at high speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the pilot makes a control input to the left. The right aileron deflects downward, and instead of raising the overall AOA of the wing, it lowers it because the aileron acts like a trim tab, twisting the wing's leading edge downward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question is asking: If the control reversal velocity is calculated to be higher than the divergence velocity, (When the wing breaks apart), how then can control reversal take place in flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer would be when it occurs near a stall.&lt;/p&gt;&#xA;" OwnerUserId="1643" LastActivityDate="2014-03-20T01:06:58.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2479" PostTypeId="2" ParentId="2476" CreationDate="2014-03-20T02:24:54.870" Score="6" Body="&lt;p&gt;Close! Here is a simplified example: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First we use GPS positions to determine the ground vector.  This is based on distance traveled and ground track over time.  It is a fairly straight-forward calculation based on the time to travel between two coordinates and their relative positions.  &lt;/li&gt;&#xA;&lt;li&gt;Then we calculate our flight vector.  This is based on the aircraft &lt;strong&gt;True&lt;/strong&gt; Airspeed (TAS) and heading.&lt;sup&gt;1&lt;/sup&gt; &lt;/li&gt;&#xA;&lt;li&gt;Lastly we use basic geometry/vector math to calculate the difference between the two vectors.  This calculated vector is the wind direction and speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;a href=&quot;http://www.skybrary.aero/index.php/True_Airspeed&quot; rel=&quot;nofollow noreferrer&quot;&gt;TAS&lt;/a&gt; is Calibrated Airspeed corrected for altitude and non-standard temperature - the speed of the aircraft relative to the airmass in which it is flying.  It is calculated using the pitot-static inputs along with the Total Air Temperature (TAT) input (if available). To get an idea of the math, take a look at &lt;a href=&quot;https://aviation.stackexchange.com/a/1796/69&quot;&gt;this answer&lt;/a&gt; of mine that calculates Mach Number, which is one of the values used to calculate TAS. Also, the TAT isn't really needed for low-speed aircraft that fly below about 100 KIAS.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-03-20T02:24:54.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2482" PostTypeId="1" AcceptedAnswerId="2483" CreationDate="2014-03-20T04:22:19.593" Score="54" ViewCount="31648" Body="&lt;p&gt;There was &lt;a href=&quot;https://aviation.stackexchange.com/questions/2186/why-are-commercial-flights-not-equipped-with-parachutes&quot;&gt;another question&lt;/a&gt; that asked why commercial flights don't have parachutes.  The almost ubiquitous response was that the parachutes would be useless because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most accidents with commercial airliners happen on take off and landing, and there is no time to parachute.&lt;/li&gt;&#xA;&lt;li&gt;In order to get to a position where 100+ people can successfully jump out, you'd most likely need to descend some 20,000 ft and then maintain straight and level for a good 3 to 5 minutes once you got past 12,000 (so people have oxygen to breathe when they jump).  And if you can descend and maintain level flight, you might as well land.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But what about in a light, single engine plane (think &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;noreferrer&quot;&gt;Cessna 172&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;noreferrer&quot;&gt;Piper Cherokee&lt;/a&gt;)?  Engine failures in small aircraft, for example, seem to be more common, so you have more accidents that start high above the ground.  Thus, you usually have a few minutes before you're going to hit the ground and there's often only 1 or 2 passengers (rather than 100). Plus, you're usually already at an altitude where you don't need oxygen to bail out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in mind, couldn't you put the plane into a shallow dive to keep it from stalling, trim it to keep it going straight and then bail out?  It seems like a somewhat practical solution, yet I have never heard of anyone doing it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do pilots often try to find a road to land on or a lake to ditch in when trouble strikes instead of just bringing a parachute and bailing out?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2018-02-15T18:26:14.477" Title="Why don't pilots parachute from small planes that are in distress?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;general-aviation&gt;&lt;parachute&gt;" AnswerCount="8" CommentCount="17" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2483" PostTypeId="2" ParentId="2482" CreationDate="2014-03-20T04:39:10.600" Score="77" Body="&lt;p&gt;Mainly because in the situation that you describe, the airplane is perfectly capable of flying.  You don't &lt;strong&gt;need&lt;/strong&gt; an engine to fly as airplanes are designed to glide without it. Part of every pilots training is how to land the airplane when this happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the same issues also apply in the smaller airplanes.  Unless the pilot and the passengers fly around with their parachutes on, it would be quite difficult to put them on in the confined space, in a high stress situation, and with the very limited time available.  Even if they did, untrained people are going to be hurt (probably quite badly) during the landing even if everything else with the jump goes well. (See my answer on your linked question for some of the things that can go wrong during the jump.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are also creating a hazard with the aircraft not being piloted and crashing into a random place on the ground.  All of this when the airplane could have just glided in for a landing in a field or on a road.  Most of these types of emergencies end quite well, and even a lot of the accidents will have fewer injuries and deaths than if people were jumping out all of the time. As an added bonus, the airplane can even be used again! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, a major structural failure that makes the aircraft incapable of flight could be a reason to jump.  This is &lt;strong&gt;extremely&lt;/strong&gt; rare however, and even if one has a parachute in this situation it may be impossible to exit the airplane safely because of high G forces and the possibility of hitting the airplane as you are both tumbling through the sky.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some manufacturers are now building &lt;a href=&quot;http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems&quot;&gt;ballistic parachutes&lt;/a&gt; into the airplane which can bring the entire airplane down safely in these situations.  This is much more safer, reliable, and does  have a positive impact on safety in these extremely bad situations.  For just an engine failure though, I doubt that most pilots would even fire the ballistic parachute if there were suitable landing spots within gliding distance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My view is that you would have a far greater safety impact by requiring everybody in a moving car to wear a helmet.  Would it improve safety?  Absolutely.  Would people want to do it?  A few would (and perhaps a few do), but the general population doesn't want to be inconvenienced by something that is only a remote possibility.  The odds of a parachute helping you in a typical GA airplane is far more remote than the odds of the helmet helping you in a car.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-20T17:45:04.067" LastActivityDate="2014-03-20T17:45:04.067" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="2484" PostTypeId="1" AcceptedAnswerId="2490" CreationDate="2014-03-20T07:53:19.217" Score="22" ViewCount="28020" Body="&lt;p&gt;If the logbook for an aircraft is lost, how does one replace it? Is the airplane still airworthy?&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="97" LastEditDate="2014-03-20T10:32:35.180" LastActivityDate="2021-02-19T19:27:36.537" Title="What happens when the logbook of an aircraft is lost?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;logging&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2485" PostTypeId="1" AcceptedAnswerId="2502" CreationDate="2014-03-20T08:13:30.000" Score="16" ViewCount="25306" Body="&lt;p&gt;I understand that tailwind is typically a good thing during your flight as it increases your ground speed and gets you to your destination faster.  Despite that I get a feeling that pilots typically get very uncomfortable when there is a significant tailwind present during landing.  Sadly, recent proof of this danger was in Aspen, Colorado &lt;a href=&quot;http://www.cnn.com/2014/01/05/us/colorado-plane-crash/&quot;&gt;accident&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Why are tailwinds bad during landing?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Given &quot;extra long&quot; runway for extended rollout, are there any dangers with landing at a higher ground speed?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How are tailwinds mitigated?  Would ATC just switch the landing direction?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="795" LastEditorUserId="15311" LastEditDate="2018-06-13T06:58:22.250" LastActivityDate="2018-11-13T14:11:25.293" Title="Why is tailwind during final approach and landing so dangerous?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;wind&gt;&lt;groundspeed&gt;" AnswerCount="8" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2486" PostTypeId="2" ParentId="2485" CreationDate="2014-03-20T08:34:00.347" Score="4" Body="&lt;ol&gt;&#xA;&lt;li&gt;because the ground speed would be greater than your airspeed, something you do not want during landing (or take-off): you need at least a certain airspeed to have enough lift, and tailwind would make you too fast w.r.t. ground, making your landing distance much bigger than actually needed&lt;/li&gt;&#xA;&lt;li&gt;it depends on how much &quot;extra long&quot; and how much &quot;higher ground speed&quot;, the aircraft manufacturer will have included tables in the Pilot Operational Handbook, you will have to consult them to verify if it safe or not.&lt;/li&gt;&#xA;&lt;li&gt;yes, it is indeed switched.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-03-20T08:34:00.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2487" PostTypeId="2" ParentId="2485" CreationDate="2014-03-20T09:05:49.710" Score="2" Body="&lt;p&gt;Just an additional human factors flavored aspect:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your speed relative to the runway is greater than usual. If you start adjusting your relative speed by your usual (headwind) visual reference, this might well lead to a stall situation - never a good thing close to the ground.&lt;/p&gt;&#xA;" OwnerUserId="95" LastActivityDate="2014-03-20T09:05:49.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2488" PostTypeId="2" ParentId="2482" CreationDate="2014-03-20T10:30:49.313" Score="14" Body="&lt;p&gt;On your comment of:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can you possibly think of an instance where having a chute would help in a GA plane?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, I can, and here's a video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/7p6hqMnsLFY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bet those guys were happy to be wearing chutes alright!&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:22:38.697" LastActivityDate="2015-10-01T19:22:38.697" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2489" PostTypeId="1" CreationDate="2014-03-20T11:13:07.680" Score="2" ViewCount="858" Body="&lt;p&gt;For fun I want to &lt;strong&gt;build a flight simulator&lt;/strong&gt; at home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are my options from most basic toy environment to more realistic set-up.&lt;br&gt;&#xA;Great if you can give for each solution a basic indication of cost (software / hardware), and if appropriate the space needed.&lt;/p&gt;&#xA;" OwnerUserId="1599" LastEditorUserId="1599" LastEditDate="2014-03-20T11:50:48.100" LastActivityDate="2014-03-20T11:50:48.100" Title="I want to build a flight simulator!" Tags="&lt;flight-simulator&gt;" AnswerCount="0" CommentCount="6" FavoriteCount="3" ClosedDate="2014-03-20T13:11:47.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="2490" PostTypeId="2" ParentId="2484" CreationDate="2014-03-20T11:41:48.410" Score="20" Body="&lt;p&gt;In order to state the plane is airworthy you must be able to show that all AD's have been complied with and that the aircraft is within annual (or 100 hour) inspection; these proofs are typically found in the logbook so no, without the logbook your aircraft is probably not airworthy. It may be possible to fly the plane legally in the US anyway if you receive authorization from your FSDO (which, I believe, would be a &quot;ferry permit&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not legally required that your logbook be complete to the beginning of time, just that it shows the current requirements are met (along with the signatures/cert numbers of the AI's that are stating them to be met). However, an incomplete logbook is very important from a resale point of view. Not having complete logs will make a plane very difficult to sell and will certainly affect the price most purchasers would be willing to pay.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-03-20T11:41:48.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2492" PostTypeId="1" AcceptedAnswerId="2499" CreationDate="2014-03-20T13:56:04.387" Score="17" ViewCount="7134" Body="&lt;p&gt;What would happen to a flying aeroplane if suddenly there is &lt;a href=&quot;http://en.wikipedia.org/wiki/Hail&quot;&gt;hail&lt;/a&gt; in the sky?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, ice the size of a brick.&lt;/p&gt;&#xA;" OwnerUserId="1375" LastEditorUserId="97" LastEditDate="2014-03-20T22:30:23.643" LastActivityDate="2014-03-21T20:20:24.603" Title="What would happen to a flying aeroplane if there's suddenly a brick-size hailstorm?" Tags="&lt;safety&gt;&lt;weather&gt;&lt;icing&gt;" AnswerCount="4" CommentCount="11" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2493" PostTypeId="2" ParentId="2492" CreationDate="2014-03-20T14:08:57.417" Score="15" Body="&lt;p&gt;Frozen precipitation comes in many forms&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hail&lt;/li&gt;&#xA;&lt;li&gt;Graupel&lt;/li&gt;&#xA;&lt;li&gt;Sleet&lt;/li&gt;&#xA;&lt;li&gt;Snow&lt;/li&gt;&#xA;&lt;li&gt;Freezing rain (technically supercooled and not frozen)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of these, hail and freezing rain are the biggest threats to aircraft and I'll focus on hail as that seems to be the topic of your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hail, especially &quot;brick sized&quot; hail require very strong updrafts in severe thunderstorms to be able to form. We typically name hail sizes by round objects (not bricks) and on the high end we have baseball and softball sized hail. Hail bigger than that does exist, but it is uncommon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These bigger hailstones are almost exclusively found very close to the updraft in supercell thunderstorms. To encounter these you really need to be flying somewhere you should not be. The turbulent conditions that will exist in the region of these hailstones is already a large threat to an airplane. Hailstones this big will severely dent the fuselage and likely shatter the windscreens. It would be a significant event. However these hailstones don't appear out of nowhere and you are extremely unlikely to see one if you aren't penetrating the worst part of severe storms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller hailstones can be further from the updraft of a storm and can be lofted some distance in the anvil (which extends downwind for many miles) in certain conditions. Here we are considering golf ball sized hail and smaller, which are still confined to being associated with thunderstorms. These hailstones will dent the aircraft skin and can possibly damage the radome and windscreens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most examples of hail damage you will find are aircraft that were on the ground as storms passed overhead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You won't find &quot;brick sized&quot; hail randomly in the atmosphere, and you should not be getting close enough to experience these if you're flying safely around thunderstorms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an image courtesy of NOAA (public domain):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BOl7k.png&quot; alt=&quot;A thunderstorm&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image depicts composite radar (on the &quot;ground&quot; in the image) and a vertical radar cross section through the storm. The area labelled &quot;Hail Core&quot; is where the very large hail is going to be formed and is falling. The extreme radar echoes in this area are entirely due to the extremely reflective properties of the hail. This is an area of intense downdraft due to the falling hydrometeors. The area labelled &quot;Weak echo region&quot; is the base of the updraft. It has a weak radar presentation, because it is fast and violent enough that vapor is not condensing and raindrops not forming until well above the ground, and it is the raindrops and larger objects that radar can show us. Hail or no hail, this is not a region you want to be flying an airplane into.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="849" LastEditDate="2014-03-21T20:20:24.603" LastActivityDate="2014-03-21T20:20:24.603" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2494" PostTypeId="2" ParentId="2354" CreationDate="2014-03-20T14:12:16.033" Score="10" Body="&lt;p&gt;Most of the above reasons are valid. I worked at Eastern airlines and we switched from the white/blue livery to polished aluminum because the weight/drag reduction vs. increased manpower cost still was overall cost effective. Remember a 747 uses around 90 gallons of paint weighing in the vicinity of 550 pounds.&lt;/p&gt;&#xA;" OwnerUserId="1656" LastActivityDate="2014-03-20T14:12:16.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2495" PostTypeId="2" ParentId="2482" CreationDate="2014-03-20T14:29:39.663" Score="3" Body="&lt;p&gt;The only time I can think of would be if you are flying over a large expanse of unpopulated mountain area.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are responsible for the damage your plane creates when it impacts with the ground, so there is no time over populated land where there is any control over the aircraft that it is appropriate to bail out of the aircraft and leave the plane flying out of control until impact.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the mountains where there is no traffic for miles bailing out might give you a better opportunity to be rescued.  A parachute can be controlled and you can put yourself in a better position to survive until rescue.  In the mountains it is much harder to land safely than an area where there are open fields or flat spaces.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over open water bailing out of the plane might give you a chance to spot and/or be spotted by nearby sailing vessels.  Though if you have some control over your aircraft then you would be better served using that control to ditch in a controlled fashion in visual range of a sailing craft than jumping from the craft.  &lt;/p&gt;&#xA;" OwnerUserId="218" LastActivityDate="2014-03-20T14:29:39.663" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2496" PostTypeId="2" ParentId="2482" CreationDate="2014-03-20T15:07:39.600" Score="2" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I believe most accidents occur during takeoff and landing when the machine and human pilots are most busy.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unless the aircraft experienced catastrophic failure I think most pilots would prefer to glide the plane down for a rough albeit survivable landing. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Some small aircraft come equipped with ballistic parachute...this is a great idea... :)&lt;/p&gt;&#xA;" OwnerUserId="1658" LastActivityDate="2014-03-20T15:07:39.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2497" PostTypeId="2" ParentId="2482" CreationDate="2014-03-20T15:23:32.103" Score="27" Body="&lt;p&gt;I compete in aerobatics where parachutes are required by the rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My personal criteria for bailing out are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Structural failure (a wing breaks off -- unlikely, as my main spar is enormous)&lt;/li&gt;&#xA;&lt;li&gt;Control failure (flutter, stuck elevator)&lt;/li&gt;&#xA;&lt;li&gt;Inability to see or control the aircraft (oil on the windscreen, maybe a bird strike)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I might jump for an engine fire just because the main fuel tank is way too close to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the engine fails I would land the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted in &lt;a href=&quot;https://aviation.stackexchange.com/a/2483/52&quot;&gt;Lnafziger's excellent answer&lt;/a&gt;, an engine is required for continued flight, but isn't truly necessary for landing :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I compare wearing a parachute to wearing a helmet in a car.  In unusual / high performance situations, it's a very good idea.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's unnecessary for the morning commute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't wear one when flying a non-aerobatic airplane.&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-03-20T15:23:32.103" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2498" PostTypeId="2" ParentId="2492" CreationDate="2014-03-20T15:32:49.823" Score="17" Body="&lt;p&gt;There was a case where an easyJet Boeing flew through a hailstorm; the accident report &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20030815-0&quot; rel=&quot;noreferrer&quot;&gt;is here, with a PDF download&lt;/a&gt; available, which lists some of the damage (which includes a cracked windscreen and damaged leading edges on wings and other surfaces).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://imgur.com/a/kfQDn&quot; rel=&quot;noreferrer&quot;&gt;There are photos showing the damage incurred&lt;/a&gt;, including the one below. Search for &quot;easyJet hailstorm damage&quot; to find more.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KWvFP.jpg&quot; alt=&quot;Dented stabilizer on easyJet aircraft&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="769" LastEditorUserId="97" LastEditDate="2014-03-20T22:32:58.543" LastActivityDate="2014-03-20T22:32:58.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2499" PostTypeId="2" ParentId="2492" CreationDate="2014-03-20T15:36:21.753" Score="15" Body="&lt;p&gt;It depends on the severity of the hailstorm. In the event of encountering large hail pieces in the sky during cruise, a pilot will generally try to climb above the storm (of course with ATC permission) to prevent damage to the airframe. However, it is always better to stay out of the hailstorm in the first place and pilots will usually try to negotiate a course avoiding the hailstorm entirely using available weather data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are much more extreme cases such as this Boeing 727 which cracked its radome &lt;em&gt;and&lt;/em&gt; its windshield after flying through a hailstorm at FL 350:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3CBHA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vF3cX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were no pax onboard as it was a cargo flight for Capital Cargo International Airlines. After the severe damage to the airplane, the crew declared an emergency and safely landed at a diversion airport. Surprisingly, the airframe was repaired and put back in service after the incident.&lt;/p&gt;&#xA;" OwnerUserId="504" LastActivityDate="2014-03-20T15:36:21.753" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2500" PostTypeId="2" ParentId="2484" CreationDate="2014-03-20T16:33:01.153" Score="14" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/2490/64&quot;&gt;mah pointed out&lt;/a&gt;, if you lose all your logbooks your aircraft/engine/propeller/avionics are no longer airworthy because they lack the documentation of required inspections, AD compliance, etc.&lt;br&gt;&#xA;Everything is still &quot;airworthy&quot; in the sense that the aircraft doesn't know anything about paperwork and will happily fly, and getting a special flight (&quot;ferry&quot;) permit from the FAA so you can take it to a mechanic to fix the paperwork will be pretty easy, but if you just go flying and something goes wrong the FAA and your insurance company will be most displeased about the lack of required paperwork.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the aircraft turning into a paperwork-pumpkin two things happen when you lose logbooks:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The value of the aircraft drops (I've seen aircraft selling for 30% less because of missing logs)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You have to &quot;reconstruct&quot; the aircraft's history and demonstrate compliance with all ADs and required inspections (an annual, an ELT check, a transponder check, a pitot/static check for IFR, etc...)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There's really not much you can do about #1 -- Logbooks are the history of the aircraft (and engine, propeller, avionics, etc.), and someone buying an aircraft is going to want to know that history.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How much a missing logbook matters is a matter of the buyer's personal opinion and what's missing. For example, I bought a plane missing Engine Log #1 (of 3). The engine has had two overhauls by well-known shops, one documented in Log #2 and one recently in Log #3, so my mechanic and I were not too concerned about the contents of Log #1.&lt;br&gt;&#xA;  Had the first &lt;em&gt;airframe&lt;/em&gt; log been missing (which documents the plane's life as a flight school trainer in Florida) there would have been a more substantial impact on the aircraft's value.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as #2 goes, &quot;reconstructing&quot; logs is usually pretty hard.&lt;br&gt;&#xA;If you're the first owner, you've always used the same shop, and your mechanic keeps &lt;em&gt;meticulous&lt;/em&gt; records they may be able to print you out a replacement log of everything that's ever been done to the aircraft and sign it off with no sweat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're not the first owner but everyone who's owned the aircraft kept meticulous records (shop invoices, etc) you still have the history even if it's not in &quot;logbook&quot; format -- it won't satisfy the FAA, but it will make the process of inspecting the aircraft and determining its airworthiness a little easier for your mechanic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're not in either of those situations your mechanic is going to have to give the aircraft a thorough going over (in addition to conducting an annual inspection they will need to verify that every AD has been complied with (or doesn't apply). That can be a &lt;em&gt;very&lt;/em&gt; time-consuming (and expensive) process - particularly if there are many &quot;inspection&quot; ADs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other details about the aircraft's history can usually be reconstructed from your national aviation authority &amp;amp; accident investigators (in the USA you would do an N-number &amp;amp; Serial Number search in &lt;a href=&quot;http://www.ntsb.gov/aviationquery/index.aspx&quot; rel=&quot;noreferrer&quot;&gt;the NTSB aviation accidents database&lt;/a&gt;, and &lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/copies_aircraft_records/&quot; rel=&quot;noreferrer&quot;&gt;request the aircraft record from the FAA&lt;/a&gt; which will include things like FAA Form 337 for major repairs, alterations, and STCs.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-11-15T00:29:15.833" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2501" PostTypeId="1" CreationDate="2014-03-20T16:53:57.100" Score="16" ViewCount="2584" Body="&lt;p&gt;Recently, the crew of an Indian airline performed a short choreographed dance sequence mid-flight on the occasion of &lt;a href=&quot;http://en.wikipedia.org/wiki/Holi&quot; rel=&quot;noreferrer&quot;&gt;Holi&lt;/a&gt;. This is, a not so rare practice amongst low-cost Indian carriers, who organize such dance sequences to celebrate special festivals (since festivals are a &lt;strong&gt;huge&lt;/strong&gt; part of Indian culture, plus publicity for the airline afterwards).&lt;/p&gt;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=Uyk3SOFPsog&quot; rel=&quot;noreferrer&quot;&gt;YouTube video&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8TkCg.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RjXcn.jpg&quot; alt=&quot;&quot; /&gt;&lt;br&gt;&#xA;&lt;em&gt;One of the pilots can be seen recording the dance on his camera.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;SpiceJet specially planned this event, and had extra cabin crew on-board the flight as a precaution. Also, during the dance, one of the pilots was in the cockpit while the other one was outside, following standard regulations.&lt;/p&gt;&#xA;&lt;p&gt;DGCA however, got wind of this, and turned out to be &lt;a href=&quot;http://indianexpress.com/article/india/india-others/watch-video-holi-dance-by-cabin-crew-onboard-aircraft-costs-spicejet-dear/&quot; rel=&quot;noreferrer&quot;&gt;not in a very festive mood&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Mid-air Holi celebrations aboard eight flights have cost SpiceJet heavily, with the DGCA issuing show cause notice to the airline and suspending two of its pilots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here's &lt;a href=&quot;http://blogs.wsj.com/indiarealtime/2014/03/20/mid-flight-dance-gets-spicejet-pilots-suspended/&quot; rel=&quot;noreferrer&quot;&gt;another news link.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;One of the arguments made by the DGCA was that this was dangerous to flight operations, and could have resulted in disaster had there been any emergency on-board during the event. Also, that this could result in an unruly cabin environment where in-flight safety of the crew and passengers would be affected.&lt;/p&gt;&#xA;&lt;p&gt;Were the actions (suspension of pilots and showcause notice to the airline) justified? Is a dancing cabin crew dangerous to flight operations?&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-14T16:38:51.783" Title="Is a dancing crew dangerous?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;crew&gt;&lt;dgca-india&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2502" PostTypeId="2" ParentId="2485" CreationDate="2014-03-20T17:17:58.397" Score="19" Body="&lt;p&gt;It's not so much a matter of &quot;pilots typically get very uncomfortable&quot; as it is &quot;pilots recognize that it is an inherently &lt;em&gt;less safe&lt;/em&gt; situation&quot;, and pilots (at least the ones you want to fly with) tend to be somewhat safety obsessed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So &lt;strong&gt;Why are tailwinds during landing &quot;bad&quot;?&lt;/strong&gt;&lt;br&gt;&#xA;The same reason tailwinds in cruise flight are good: you're moving over the ground at a higher speed.&lt;br&gt;&#xA;The amount of energy the aircraft has (and thus its landing distance) is roughly proportional to the square of the &lt;i&gt;ground&lt;/i&gt;speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's consider the plane I fly as an example (a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot;&gt;Piper Cherokee&lt;/a&gt;) because I know the numbers:&lt;br&gt;&#xA;if I'm flying by the book then when the wheels of my plane hit the ground my indicated airspeed should be around 45 knots.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;No Wind&lt;/strong&gt;&lt;br&gt;&#xA;If there's no wind my ground speed and my indicated airspeed will be about the same - my brakes will have to slow me from 45 knots to a stop before I run out of runway.&lt;br&gt;&#xA;The brakes on the Cherokee aren't Porsche brakes (they're tiny little things), but they're up to the task and a book-perfect landing would have me stopped in 600 feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;15-Knot Headwind&lt;/strong&gt;&lt;br&gt;&#xA;A 15 knot headwind reduces my groundspeed to 30 knots - at 2/3 the speed I can stop much sooner with the same braking force, which means less wear on the brakes and a greater safety margin of runway remaining.&lt;br&gt;&#xA;A book-perfect landing in these conditions would have me stopped in about 270 feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;15-knot Tailwind&lt;/strong&gt;&lt;br&gt;&#xA;A 15 knot tailwind increases my groundspeed to 60 knots. The tiny little brakes on the Cherokee &lt;em&gt;CAN&lt;/em&gt; stop me, but they're going to take much longer to do so: A book-perfect landing would take over 1000 feet to stop (nearly twice the &quot;normal&quot; no-wind landing roll).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The big consideration above is landing distance -- as you noted in your question you can solve that with a longer runway (more pavement means more room to stop), but &lt;strong&gt;there are other dangers with tailwind landings&lt;/strong&gt;, mainly in the fact that &lt;em&gt;Landings don't always go according to plan&lt;/em&gt;.&lt;br&gt;&#xA;The slower your groundspeed at landing the less energy you have to get rid of if something goes wrong&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the three landings I outlined above, but let's add a problem to the mix: One of my tires blows right at touchdown, and the plane veers off the runway into a ditch.&lt;br&gt;&#xA;There is much less energy to dissipate with a 15-knot headwind (30kt groundspeed) than there is with a 15-knot tailwind (60kt groundspeed) - it's roughly the difference between crashing your car driving through a school zone versus speeding on a highway.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Fortunately it's really easy to avoid landing with a tailwind -- &lt;em&gt;most&lt;/em&gt; runways are bidirectional (Aspen, which you mentioned in your question, is a notable exception due to geography).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC (or at uncontrolled fields, the pilots themselves) will &quot;turn the airport around&quot; once a certain tailwind limit is reached.  Precisely when that happens depends on the airport and the traffic mix (at my home field, with mostly small piston aircraft, ATC will typically switch the runway when the tailwind component exceeds 5 knots - at JFK they might land a jet with a 10-knot tailwind rather than messing up the arrivals).&lt;br&gt;&#xA;Of course there's nothing that says a pilot has to accept a landing with a tailwind: If the pilot is not comfortable with the conditions they can request a runway aligned so the winds are more favorable. (There is a &lt;a href=&quot;http://www.avweb.com/avwebflash/news/jkf_construction_crosswind_American_pilots_clearance_crosswind_emergency_202510-1.html&quot;&gt;somewhat famous case of an airline pilot at JFK&lt;/a&gt; who ultimately decided to declare an emergency to ensure a landing on a favorable runway). &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-20T17:17:58.397" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2503" PostTypeId="2" ParentId="2501" CreationDate="2014-03-20T17:37:20.027" Score="27" Body="&lt;p&gt;Well I suppose the answer depends on whether or not the flight crew are good dancers: If my uncoordinated self was trying to bust a move in an airline cabin I'd probably wind up kicking someone in the face, but these folks seem to be doing OK.&lt;br&gt;&#xA;I can only assume dance lessons are part of SpiceJet's crew training program :-)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Alright, in all seriousness - &lt;em&gt;there is increased risk any time every person onboard isn't securely strapped into their seats&lt;/em&gt;. There have been incidents (&lt;a href=&quot;http://www.cnn.com/2014/02/18/travel/united-airlines-turbulence/&quot;&gt;recent ones&lt;/a&gt;) where flight crew walking about the cabin have been injured due to unexpected turbulence, and those same unrestrained people can essentially become human projectiles to injure others onboard.&lt;br&gt;&#xA;That said I personally don't think the cabin crew doing a mid-flight dance routine poses a significant safety risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that one of the pilots was out of the cockpit recording it is slightly more questionable, and may be what has the DGCA upset in this situation. While there are procedures for having one pilot off the flight deck those provisions are generally for &lt;em&gt;necessary&lt;/em&gt; things (like a trip to the bathroom, or investigating a systems fault). The intent is for the cockpit to be manned by two qualified pilots at all times.&lt;br&gt;&#xA;If an emergency were to have happened during this dance routine the pilot we see in the video would have had to get back to the cockpit, strap in, and put on a headset (&amp;amp; possibly an oxygen mask) before being of much use.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-20T17:37:20.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2504" PostTypeId="1" CreationDate="2014-03-20T17:41:13.070" Score="7" ViewCount="668" Body="&lt;p&gt;In the other questions about parachutes on this site, it has been stated that the aircraft would have to be flying straight and level to facilitate a jump. However, there were quite a few pilots during WWII whose planes were not flying straight and level and who still managed to escape. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a difference between then and now that I am not catching?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2019-02-26T02:13:46.573" Title="Why does an aircraft have to be flying straight and level to facilitate a jump?" Tags="&lt;parachute&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2505" PostTypeId="2" ParentId="2504" CreationDate="2014-03-20T17:47:46.457" Score="6" Body="&lt;p&gt;One of the reasons why many WW2 pilots did not make it out were the &lt;strong&gt;G-forces and acceleration in directions other than the door when they had to get out&lt;/strong&gt;. The bailing out survival rate appears to be correlated to the ease of exit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're going to have a smooth and safe departure, you're happiest doing it during level flight when there's no interference from plane motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/61UWD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/61UWD.jpg&quot; alt=&quot;bail&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.lonesentry.com/blog/wp-content/uploads/2010/10/bail-out-b17-bomber-bailout.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;lonesentry.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/klT30.jpg&quot; alt=&quot;fire&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-26T02:13:46.573" LastActivityDate="2019-02-26T02:13:46.573" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2506" PostTypeId="1" AcceptedAnswerId="2521" CreationDate="2014-03-20T18:25:33.380" Score="11" ViewCount="3246" Body="&lt;p&gt;Assuming Malaysia Airlines Flight 370 ditched in the ocean, and surviving passengers and crew were floating around in their inflatable vests, how long could they survive?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there data about the longest survival under such conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few examples of people surviving for months in tiny boats, but there they could gather rainwater and catch fish, obviously impossible in just a lifejacket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: although I mentioned a specific flight and lifejackets, the question is intended to be general for ditching in the ocean.&lt;/p&gt;&#xA;" OwnerUserId="1307" LastEditorUserId="1307" LastEditDate="2014-03-21T07:14:24.593" LastActivityDate="2014-03-21T07:14:24.593" Title="How long can passengers survive after ditching in the ocean?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;ditching&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2507" PostTypeId="1" CreationDate="2014-03-20T18:47:04.437" Score="24" ViewCount="5243" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2501/is-a-dancing-crew-dangerous&quot;&gt;This question&lt;/a&gt; shows a couple of air hostesses dancing during mid-flight and the co-pilot came out of the cabin to record it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This made me wonder:  Can flight crew or passengers moving around in flight cause the airplane to stall?&lt;/p&gt;&#xA;" OwnerUserId="1664" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2017-05-02T20:18:39.350" Title="Can passenger movement in an airliner make it stall?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;airliner&gt;&lt;weight-and-balance&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2509" PostTypeId="1" AcceptedAnswerId="2518" CreationDate="2014-03-20T20:15:16.260" Score="3" ViewCount="1122" Body="&lt;p&gt;Reading the requirements for MEL it is confusing which things must be done in a multi-engine, and which things carry over from SEL. If I already have SEL do I need to do a cross country in a multi-engine? Assuming I can meet the PTS for MEL, what other requirements are there?&lt;/p&gt;&#xA;" OwnerUserId="36" LastActivityDate="2014-04-09T03:46:13.993" Title="What are the requirements for a PPL to upgrade from SEL to MEL?" Tags="&lt;faa-regulations&gt;&lt;multi-engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2510" PostTypeId="2" ParentId="2507" CreationDate="2014-03-20T20:23:02.530" Score="4" Body="&lt;p&gt;An aircraft stalls when it exceeds its critical angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless the dancing flight attendants all gather aft, and are &lt;em&gt;much&lt;/em&gt; heavier than any normal human could be (and even then), I think it's not possible for them (dancing, or being wall flowers) to modify the aircraft's angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short: no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further information on aircraft stalls: &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_(flight)&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Stall_(flight)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-03-20T20:23:02.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2511" PostTypeId="1" CreationDate="2014-03-20T20:25:17.520" Score="9" ViewCount="929" Body="&lt;p&gt;A recent news item mentioned that &quot;black boxes&quot; are typically stored in the tail section of an aircraft to maximize their odds of surviving a catastrophic incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they're stored in the rear of the aircraft, presumably flight data and cockpit voice data is transmitted via wires which run the length of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aren't these susceptible to damage during an incident? There have been incidents of explosions and fires which damage flight control cables - aren't the FDR and CVR susceptible in the same way?&lt;/p&gt;&#xA;" OwnerUserId="1666" LastEditorUserId="64" LastEditDate="2014-03-24T22:22:02.917" LastActivityDate="2014-03-24T22:22:02.917" Title="How is data transmitted to CVR and FDR?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2512" PostTypeId="2" ParentId="2507" CreationDate="2014-03-20T20:35:24.253" Score="19" Body="&lt;p&gt;Theoretically? Yes.&lt;br&gt;&#xA;Practically? No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers moving around in an aircraft will have some effect on the balance (center of gravity) of that aircraft, but the proportion of weight for a few flight attendants or passengers moving around on a modern airliner is likely so small as to be negligible. It's not enough of a change to exceed the control authority of the aircraft and cause it to pitch up enough to stall (unless &lt;a href=&quot;https://aviation.stackexchange.com/a/2510/64&quot;&gt;as mah notes&lt;/a&gt; you have a substantial number of &lt;em&gt;extremely heavy&lt;/em&gt; folks on board and they all stand right up against the aft bulkhead - and even then it's not likely).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I can't find the link to it, but I recall either reading about or hearing about a mostly-empty flight (I want to say on some kind of smaller multi-engine piston aircraft)in in which the half-dozen or so passengers (having had a few &quot;adult beverages&quot;) decided to play a friendly prank on the pilots by slowly moving to the furthest aft seats, waiting there for a while, and then slowly moving back to the furthest forward seats.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I recall the story the aircraft in question had no autopilot, so the pilots had to manually re-trim the aircraft after each round of seat changes. The end result ultimately being that the pilots announced that everyone had to pick a seat and stay in it, or the beer cooler would be locked for the remainder of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(As you can probably imagine there was no further need to re-trim due to unexpected CG changes following that announcement.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-03-20T20:35:24.253" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2513" PostTypeId="2" ParentId="2511" CreationDate="2014-03-20T20:51:38.157" Score="9" Body="&lt;p&gt;You are very correct that this can happen- If i'm not wrong, what happened during the last 6 minutes of &lt;a href=&quot;http://en.wikipedia.org/wiki/Swissair_Flight_111&quot;&gt;Swissair Flight 111&lt;/a&gt; will never be known for this reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general however, by the time the fire would spread to this extent the CVR and/or FDR would probably have picked up some hint of fire and the reason. To increase survivability, the FDR and CVR are connected off separate power buses ('boards'), so I'd imagine the cables for each not exactly next to each other on the fuselage, and if one trips, the other one will hopefully still run for a bit longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpit voice recorder operates a simple microphone I believe, so I'd expect that it wouldn't be much more complicated than your computer microphone. The data would probably be converted from analog to digital before being transmitted backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the 88 parameters that the Flight Data recorder currently requires, I'd imagine that there would be a serial connection from each relevant part- each flight computer, engine etc. all leading to the back of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.ntsb.gov/doclib/manuals/FDR_Handbook.pdf&quot;&gt;FDR Handbook&lt;/a&gt;- NTSB&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-20T21:04:05.977" LastActivityDate="2014-03-20T21:04:05.977" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2514" PostTypeId="2" ParentId="2507" CreationDate="2014-03-20T21:09:21.123" Score="9" Body="&lt;p&gt;There was a &lt;a href=&quot;http://www.telegraph.co.uk/news/worldnews/africaandindianocean/democraticrepublicofcongo/8078612/Aircraft-crashes-after-crocodile-on-board-escapes-and-sparks-panic.html&quot;&gt;crash&lt;/a&gt; in the Congo that is presumed to be caused when a loose crocodile in the cabin sparked panic, and catastrophically shifted the balance of the aircraft. Not something you hear every day.&lt;/p&gt;&#xA;" OwnerUserId="1668" LastActivityDate="2014-03-20T21:09:21.123" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2515" PostTypeId="2" ParentId="2506" CreationDate="2014-03-20T21:17:42.783" Score="4" Body="&lt;p&gt;Well, there chances for extended survival is not exceedingly generous, according to the FARs 91.509 and 135.167. Bear in mind that it probably wouldn't take so long for a larger aircraft before they notice that it was missing.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;FARs 135.167:&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Except where the Administrator, by amending the operations&#xA;  specifications of the certificate holder, requires the carriage of all&#xA;  or any specific items of the equipment listed below for any overwater&#xA;  operation, or, upon application of the certificate holder, the&#xA;  Administrator allows deviation for a particular extended overwater&#xA;  operation, no person may operate an aircraft in extended overwater&#xA;  operations unless it carries, installed in conspicuously marked&#xA;  locations easily accessible to the occupants if a ditching occurs, the&#xA;  following equipment:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) An approved life preserver equipped with an approved survivor&#xA;  locator light for each occupant of the aircraft. The life preserver&#xA;  must be easily accessible to each seated occupant.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Enough approved liferafts of a rated capacity and buoyancy to&#xA;  accommodate the occupants of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Each liferaft required by paragraph (a) of this section must be&#xA;  equipped with or contain at least the following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) One approved survivor locator light.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) One approved pyrotechnic signaling device.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Either— (i) One survival kit, appropriately equipped for the route&#xA;  to be flown; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) One canopy (for sail, sunshade, or rain catcher);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) One radar reflector;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) One liferaft repair kit;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(v) One bailing bucket;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vi) One signaling mirror;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vii) One police whistle;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(viii) One raft knife;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ix) One CO2 bottle for emergency inflation;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(x) One inflation pump;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xi) Two oars;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xii) One 75-foot retaining line;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xiii) One magnetic compass;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xiv) One dye marker;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xv) One flashlight having at least two size “D” cells or equivalent;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xvi) A 2-day supply of emergency food rations supplying at least&#xA;  1,000 calories per day for each person;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xvii) For each two persons the raft is rated to carry, two pints of&#xA;  water or one sea water desalting kit;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xviii) One fishing kit; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xix) One book on survival appropriate for the area in which the&#xA;  aircraft is operated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I'd guess the answer is around three or four days perhaps. If they got to the galley onboard within an hour before the aircraft flooded, they might have a bit more...&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-03-20T21:17:42.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2516" PostTypeId="2" ParentId="2472" CreationDate="2014-03-20T23:33:29.350" Score="43" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;how they can come up with such specific paths?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Diagrams in news organisations graphics published in March and April 2014 vary widely in what they show and appear to be artistic impressions. These should not be relied on in any way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To calculate a variety of likely flight paths, it seems Inmarsat engineers, and other parties to the official investigation, used a number of sets of information including but not limited to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;satellite communication timings giving distances from satellite.&lt;/li&gt;&#xA;&lt;li&gt;satellite communications frequency variations giving relative motions.&lt;/li&gt;&#xA;&lt;li&gt;knowledge of variations in satellite orbit.&lt;/li&gt;&#xA;&lt;li&gt;knowledge of variations in satellite temperatures (daylight exposure etc)&lt;/li&gt;&#xA;&lt;li&gt;knowledge about signal processing timings in various equipment.&lt;/li&gt;&#xA;&lt;li&gt;characteristics of the aircraft (load, fuel consumption rates, etc)&lt;/li&gt;&#xA;&lt;li&gt;autopilot modes of operation (route, heading, track. magnetic, true, ...)&lt;/li&gt;&#xA;&lt;li&gt;etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The analysis was improved and refined over time, resulting in newer estimates of the flight path and final coordinates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other independent groups of people have published their own analyses which come to broadly similar conclusions. E.g. the self-titled &quot;Independent Group&quot; associated with &lt;a href=&quot;http://www.duncansteel.com/&quot; rel=&quot;noreferrer&quot;&gt;Duncan Steel&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Inmarsat paper, October 7 2014.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A paper &quot;&lt;a href=&quot;http://journals.cambridge.org/download.php?file=%2FNAV%2FNAV68_01%2FS037346331400068Xa.pdf&amp;amp;code=519acae8c81cde4a5695a37a3d8fa71f&quot; rel=&quot;noreferrer&quot;&gt;The Search for MH370&lt;/a&gt;&quot; published in the Journal of Navigation by Ashton et al. (2014). describes in some detail how the Inmarsat engineers used satellite data to determine probable flight paths for the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;ATSB report. August 18 2014&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Australian Transport Safety Bureau released a &lt;a href=&quot;http://www.atsb.gov.au/media/5243942/ae-2014-054_mh370_-_definition_of_underwater_search_areas_18aug2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;revised version&lt;/a&gt; of their June 26 report. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wFDhn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;ATSB report. June 26 2014&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Australian Transport Safety Bureau release a 54-page report &quot;&lt;a href=&quot;http://www.jacc.gov.au/media/releases/2014/june/mr052_MH370_Definition_of_Sea_Floor_Wide_Area_Search.pdf&quot; rel=&quot;noreferrer&quot;&gt;MH370 - Definition of &#xA;Underwater Search Areas&lt;/a&gt;&quot; which goes into greater detail than any prior official report and shows much more of the calculations that were performed on the Burst Frequency Offsets to calculate probable final position of MH370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular the appendices describe some  equations that were used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pwozY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;A small extract from the report&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Raw Satellite Data. May 27 2014&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://i2.cdn.turner.com/cnn/2014/images/05/27/flight.370.data.logs.pdf&quot; rel=&quot;noreferrer&quot;&gt;raw satellite data&lt;/a&gt; was made available on 27/5/2014 in response to requests from relatives of the passengers. This shows burst timing offsets (BTO) and Burst Frequency Offsets (BFO) for communications between the Inmarsat ground station and MH370.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;ATSB document. May 26 2014.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Australian ATSB released a &lt;a href=&quot;http://www.atsb.gov.au/media/5205507/MH370_Considerations%20on%20defining_FactSheet.pdf&quot; rel=&quot;noreferrer&quot;&gt;factsheet&lt;/a&gt; that outlines what is known and reiterates the general description of how the tracks were calculated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SLqPt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sBpbo.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By &#xA;  taking the maximum speed of the aircraft into account, the rings can be reduced in length to arcs – there &#xA;  are some areas of the rings it simply could not have reached. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There are a large number of speeds and headings that can be &#xA;  consistent with a BFO recording. These are limited, however, by the operational constraints of the aircraft. &#xA;  Candidate paths of different speeds were created which met the BTO ring location/time constraints and &#xA;  the predicted BFO values of these paths have been compared with the recorded values. The better the &#xA;  match, the higher the probability that the path was close to that of MH370.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Release of raw data from satellites. May 27th 2014&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On May 21st 2014 CNN &lt;a href=&quot;http://edition.cnn.com/2014/05/20/world/asia/malaysia-missing-plane/&quot; rel=&quot;noreferrer&quot;&gt;reported&lt;/a&gt; that the satellite data and description of analysis would be published. No date has been specified.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;In line with our commitment towards greater transparency, all parties are working for the release of the data communication logs and the technical description of the analysis for public consumption,&quot; Inmarsat and the Malaysian aviation officials said in a joint statement.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Inmarsat Statement. March 24 2014&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On March 24th 2014, Inmarsat stated that a new analysis of the records of satellite handshakes with MH370 were able to use doppler effects in the signals together with an analysis of similar satellite handshake data from other Malaysian 777s to determine that MH370 flew into the Indian Ocean and ruled out flight paths to the previously described northern corridor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uxIpz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/MzzTu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;From &lt;a href=&quot;https://www.facebook.com/permalink.php?story_fbid=740971779281171&amp;amp;id=178566888854999&amp;amp;stream_ref=10&quot; rel=&quot;noreferrer&quot;&gt;INFORMATION PROVIDED TO MH370 INVESTIGATION BY UK AIR ACCIDENTS INVESTIGATION BRANCH (AAIB)&#xA;25/03/14&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Malaysian Defence Minister statement. March 21 2014. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On March 21st, a little light was shed on this process by a statement attributed by &lt;a href=&quot;http://www.nst.com.my/latest/font-color-red-missing-mh370-font-hishammuddin-s-full-statement-on-march-21-1.525115&quot; rel=&quot;noreferrer&quot;&gt;New Straights Times&lt;/a&gt; to Malaysian Defence Minister and acting Transport Minister Datuk Seri Hishammuddin Hussein.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The investigations team received the complete &lt;strong&gt;raw Inmarsat satellite data&lt;/strong&gt;, which included the &lt;strong&gt;six handshakes&lt;/strong&gt; at approximately 3 pm on Wednesday, March 12.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;This type of data is not normally used in investigations of this sort.&#xA;  It is only because we have so little other information to go on in this difficult and unprecedented situation that the data is being used.    &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Upon receiving the raw data, the Malaysian authorities immediately discussed with the US team how this information might be used. The US team and the investigations team then &lt;strong&gt;sent the data to the US&lt;/strong&gt;, where further processing was needed before it could be used.    &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Initial results were received on Thursday, March 13 at approximately 1.30 pm, but it was agreed by the US team and the investigations team that further refinement was needed, so the data was again sent back to the US.    &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;The results were received at approximately 2.30 pm on Friday, March 14 and presented to the investigations team at a high-level meeting at 9 pm on Friday.&#xA;  The &lt;strong&gt;UK AAIB&lt;/strong&gt;, who had also been processing this data independently, presented their results - which &lt;strong&gt;concurred&lt;/strong&gt; with ours and those of the US team – at that meeting.   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;The Prime Minister was briefed on this satellite information at 8 am Saturday, March 15 and publicly announced it at the press conference at Saturday lunchtime.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(my emphasis)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the above does not describe the actual calculations involved. However it does confirm that the satellite data had &lt;strong&gt;six&lt;/strong&gt; handshakes (presumably at hourly intervals up to 08:11).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Early speculation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The graphic below, illustrates one idea for how these track might have been deduced. It is a result of speculation rather than a reporting of information actually provided by the people who made the calculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The graphic suggests that the NTSB calculated possible paths based on data that is not public and that the NTSB were able to assign probabilities to those paths. As far as I know, neither Inmarsat, the NTSB nor the Australian government (or it's agencies) have made public the data or method of calculating these tracks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The graphic below suggests several Inmarsat pings were used (the example shows 01:11, 02:11, 04:11, 05:11, 06:11, 07:11 and 08:11 but these are probably speculation). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far as is publicly known, there was no ping at 09:11 or later which suggests the flight ended between 08:11 and 09:11. This is broadly consistent with maximum fuel range of the aircraft. The labelled NTSB solutions suggest that NTSB calculated that no other &lt;em&gt;constant speed (and heading?) tracks&lt;/em&gt; fit the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rzLFT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;source &lt;a href=&quot;https://twitter.com/_AntiAlias_&quot; rel=&quot;noreferrer&quot;&gt;Scott Henderson&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which says ...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For a constant speed track, distance between ping arc intersections will be equal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NTSB solutions are based on constant speed straight track. Curve in track shown due to map projection&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A later version of this graphic adds a disclaimer saying that the tracks and zones are not accurate and are symbolic only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We do know that NTSB sent staff to Malaysia to assist in the search. We know that Inmarsat provided data to the investigating teams.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-04-08T13:59:56.280" LastActivityDate="2015-04-08T13:59:56.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2517" PostTypeId="2" ParentId="2408" CreationDate="2014-03-21T00:04:56.780" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;A plane has sensors that should transmit data back somewhere when it hits water correct?&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This isn't really correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CVR/FDR/ULB&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cockpit Voice recorder (CVR) and Flight Data Recorder (FDR) don't transmit data. They do have attached to each of them an Underwater Locator Beacon (ULB) but this doesn't transmit data either. When submerged, it sends out a sonar ping every 50 seconds for up to 30 days. This sonar signal can be detected by an immersed sonar sensor in the near vicinity (maybe a couple of miles), not across thousands of miles of open ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EPIRB/ELT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ships/boats typically carry an Emergency Position Indicating Radio Beacon (EPIRB) designed to start transmitting a location signal to satellites when the ship or boat capsizes or sinks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft equivalent is the Emergency Locator Beacon (ELT) but, in the USA, from what I've read, this is only mandated for small private aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial planes that fly scheduled routes are not required to have an ELT (I imagine the regulators thought that ATC communication, transponders and ACARS would together provide adequate location data)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;787s do have ELTs fitted, &lt;a href=&quot;http://www.businessinsider.com/boeing-dreamliner-fire-linked-to-elt-2013-7&quot; rel=&quot;nofollow noreferrer&quot;&gt;somewhat notoriously&lt;/a&gt;. I've seen nothing to suggest that 10-year-old 777s do.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is it possible that these can be turned off/damaged?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ULBs cannot be turned off in flight - because they are not on. Since the CVR and FDR are at the rear of airliners the ULB is not accessible from the cockpit and probably cannot be easily disabled. A ULB would have to be &lt;a href=&quot;http://www.youtube.com/watch?v=mQehX0rVYuY&quot; rel=&quot;nofollow noreferrer&quot;&gt;disassembled&lt;/a&gt; &lt;em&gt;(see 02:55 onwards)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ELT, if carried, is typically fixed to the top of the aircraft and designed to break away if a plane sinks. I imagine this makes it difficult for the crew to access it and disable it in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eYN4I.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;yes, ELTs can be damaged.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-03-21T00:34:55.317" LastActivityDate="2014-03-21T00:34:55.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2518" PostTypeId="2" ParentId="2509" CreationDate="2014-03-21T00:57:26.050" Score="6" Body="&lt;p&gt;The appropriate paragraph of Part 61 of CFR 14 is 61.63 (emphasis mine, the '&lt;em&gt;unless&lt;/em&gt;' part does not apply in your case):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) &lt;strong&gt;Additional aircraft class rating&lt;/strong&gt;. A person who applies for an&#xA;  additional class rating on a pilot certificate:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Must have a logbook or training record endorsement from an&#xA;  authorized instructor attesting that the person was found competent in&#xA;  the appropriate aeronautical knowledge areas and proficient in the&#xA;  appropriate areas of  operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Must pass the practical test.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) &lt;strong&gt;Need not meet the specified training time requirements&#xA;  prescribed by  this part that apply to the pilot certificate for the&#xA;  aircraft class rating sought;&lt;/strong&gt; unless, the person only holds a&#xA;  lighter-than-air category rating with a balloon class rating and is&#xA;  seeking an airship class rating, then that person must receive the&#xA;  specified training time requirements and  possess the appropriate&#xA;  aeronautical experience.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Need not take an additional knowledge test, provided the applicant&#xA;  holds an airplane, rotorcraft, powered-lift, weight-shift-control&#xA;  aircraft, powered parachute, or airship rating at that pilot&#xA;  certificate level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, to answer your question, no, you do not need a cross-country, you do not need any solo time in a multiengine airplane, either. All you need is a sign off from your instructor.&lt;/p&gt;&#xA;" OwnerUserId="1343" LastEditorUserId="72" LastEditDate="2014-04-09T03:46:13.993" LastActivityDate="2014-04-09T03:46:13.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2519" PostTypeId="2" ParentId="2492" CreationDate="2014-03-21T02:20:07.317" Score="2" Body="&lt;p&gt;Most of what I know has been mentioned, and excellent photographs!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When ice and water go into the air intakes of the jet engines, the ice gets rapidly chopped up into tiny pieces -- those spinning things you can see in the front of the the engine are turbines that slice and then compress the air going through, so the engine has more air to burn with, which generates more energy. It burns, and the exhaust comes out the back. At the back, the exhaust spins the whole turbine assembly, more air goes in, and so forth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've talked with SR-71 Blackbird pilots who tell me &quot;essentially nothing&quot; happens if a bucketload of ice and snow goes into those engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The things to actually watch out for are, first, as mentioned, impacts, and second, more subtly, is ice can form on the wings. The ice screws up the shape of the wing (&quot;airfoil&quot;), and that shape is what generates lift. Too much icing can make a plane fall out of the sky.&#xA;The planes generally do have anti-icing measures -- mechanical, electrical heat -- and this is why the wings and cockpits are sprayed with de-icer before they back away from the gate when it's cold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That helps some, but if you encounter wing icing, it's best to turn around and land, and call it a day!&lt;/p&gt;&#xA;" OwnerUserId="1673" LastEditorUserId="97" LastEditDate="2014-03-21T02:40:29.100" LastActivityDate="2014-03-21T02:40:29.100" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2520" PostTypeId="1" AcceptedAnswerId="2837" CreationDate="2014-03-21T02:25:35.160" Score="13" ViewCount="6294" Body="&lt;p&gt;Something that just popped into my head: I've been on a few easyJet and Ryanair flights where a lot of passengers clap and cheer on touchdown. Would the pilots be able to hear this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example I found by &lt;a href=&quot;https://www.youtube.com/results?search_query=clapping%20plane&amp;amp;sm=3&quot; rel=&quot;noreferrer&quot;&gt;searching YouTube&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/9NMaVIVukjs?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems pretty commonplace... but can the pilots hear them? I guess it would be distracting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just something I was wondering!&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:11:45.180" LastActivityDate="2015-10-01T19:11:45.180" Title="Can pilots hear their passengers clapping on touchdown?" Tags="&lt;landing&gt;&lt;passenger&gt;&lt;airliner&gt;&lt;pilots&gt;&lt;noise&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2521" PostTypeId="2" ParentId="2506" CreationDate="2014-03-21T02:33:18.527" Score="10" Body="&lt;p&gt;Well, your scenario is a bit unlikely because if the aircraft did ditch in the ocean they would have the emergency rafts and slides to take cover in instead of &quot;floating around in their inflatable vests&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;strong&gt;if&lt;/strong&gt; someone were floating in the ocean without any protection, how long they could survive depends on various factors.  Temperature is the biggest factor in the amount of time before they would succumb to hypothermia.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at &lt;a href=&quot;http://www.ospo.noaa.gov/data/sst/contour/global_small.c.gif&quot;&gt;this chart&lt;/a&gt; to figure out the average temperature of the area in question.  If we go by the &lt;a href=&quot;http://www.cbsnews.com/news/malaysia-airlines-flight-370-possible-debris-from-missing-plane-spotted/&quot;&gt;latest news&lt;/a&gt;, that is going to be somewhere in the neighborhood of 14C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.seagrant.umn.edu/coastal_communities/hypothermia&quot;&gt;This page&lt;/a&gt; says that the &lt;em&gt;Expected Time of Survival&lt;/em&gt; is 1 to 6 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same page also says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Maximize your chances of surviving by:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Wearing a personal flotation device (PFD)&lt;/li&gt;&#xA;  &lt;li&gt;Adopting a survival position&lt;/li&gt;&#xA;  &lt;li&gt;Keeping clothing on&lt;/li&gt;&#xA;  &lt;li&gt;Getting as much of body out of the water as possible&lt;/li&gt;&#xA;  &lt;li&gt;Remaining still and in place UNLESS a floating object, another person, or the shore is nearby&lt;/li&gt;&#xA;  &lt;li&gt;Keeping a positive mental outlook (a will to survive really does matter)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;Swimming isn't recommended unless there is little chance of being&#xA;  rescued and shore is less than a mile away. Putting on a PFD after&#xA;  falling into cold water is almost impossible – SO WEAR IT. If you find&#xA;  yourself in cold water without a PFD and nothing to climb onto, tread&#xA;  water. Traditional drown-proofing by repeatedly lowering your head&#xA;  into the water and floating speeds up heat loss.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Lots more information is available on that page!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-21T02:33:18.527" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2522" PostTypeId="1" AcceptedAnswerId="2527" CreationDate="2014-03-21T02:37:43.033" Score="8" ViewCount="677" Body="&lt;p&gt;I was reading &lt;a href=&quot;http://news.bbc.co.uk/1/hi/world/americas/4780571.stm&quot;&gt;a BBC FAQ&lt;/a&gt; about Federal Air Marshals, which has this chilling quote in it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A gunfight on a passenger airliner is seen as an option only of last resort.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Presuming an air marshal has to discharge his weapon on-board, and it goes through the fuselage, would this be likely to cause an &lt;a href=&quot;https://en.wikipedia.org/wiki/Uncontrolled_decompression&quot;&gt;explosive decompression&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-21T02:59:40.580" LastActivityDate="2014-03-21T03:03:09.120" Title="Would discharging a firearm in-flight cause an explosive decompression?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;cabin-pressure&gt;&lt;fuselage&gt;&lt;fams&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2523" PostTypeId="2" ParentId="2511" CreationDate="2014-03-21T02:37:57.023" Score="5" Body="&lt;p&gt;Most airplanes implement data buses such as &lt;a href=&quot;http://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;noreferrer&quot;&gt;ARINC 429&lt;/a&gt; which describes the physical interface and a standard protocol allowing different devices to communicate and exchange data with eachother.  The A380 and 787 use ethernet as the phyiscal layer but still use an ARINC defined protocol for communications over ethernet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just about all of the electronic parts of an airplane communicate over these buses as there are many sensors and the different devices need data from a different subset of those sensors.  What the flight data recorder, as well as &lt;a href=&quot;http://en.wikipedia.org/wiki/FOQA&quot; rel=&quot;noreferrer&quot;&gt;FOQA (flight operations quality assurance)&lt;/a&gt; boxes do is tap into the data bus and record what is happening at regular intervals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are correct that the placement of these devices necessitate that the wiring for the data bus extends to the rear of the airplane.  This may not be the only reason though as in the rear of some airplanes you have engines, halon bottles, hydraulic actuators, smoke detectors, door sensors, pressurization controls (outflow valves).  The FDR doesn't need all of this data, but FOQA might use it and the EICAS system needs all of it, so the data bus will always extend the length of the airplane.   This does make it susceptible to damage, but so are the flight control cables, hydraulic lines, bleed air lines, fuel lines, etc that may also be routed to the rear of the airplane.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-21T02:37:57.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2524" PostTypeId="5" CreationDate="2014-03-21T02:38:52.350" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-21T02:38:52.350" LastActivityDate="2014-03-21T02:38:52.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2525" PostTypeId="4" CreationDate="2014-03-21T02:38:52.350" Score="0" Body="Federal Air Marshal Service" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-21T03:53:09.287" LastActivityDate="2014-03-21T03:53:09.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2526" PostTypeId="2" ParentId="2520" CreationDate="2014-03-21T02:44:10.563" Score="20" Body="&lt;p&gt;We can in my airplane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Dassault-Falcon-50/0209264/&amp;amp;sid=6104af782b28b80af3b45e33578114d4&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xkImt.jpg&quot; alt=&quot;Falcon 50&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quite frankly, I'm usually a little insulted when it happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were they actually so fearful for their lives and are now so happy to be alive that they need to applaud the heroic pilots?  Sorry, but unless it's a true emergency and we did actually just save their lives, I'm not putting them in a situation where they are actually at risk.  In this case, I was just doing my job.  Do you applaud the waiter or waitress who gets your order right??  :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as airliners, I'm pretty sure that the pilots can hear you too if everyone is clapping but someone with experience on that should confirm whether or not this is true.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Disclaimer:  This isn't the &lt;strong&gt;actual&lt;/strong&gt; airplane that I fly, but it is the same kind.  Notice also that we don't have a door to our cockpit so this makes it much easier to hear what is going on in back.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-21T03:55:01.850" LastActivityDate="2014-03-21T03:55:01.850" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="2527" PostTypeId="2" ParentId="2522" CreationDate="2014-03-21T02:47:57.817" Score="9" Body="&lt;p&gt;No, there was actually an episode of Myth Busters about this exact subject:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=Fi1_1l7M8FA&quot;&gt;http://www.youtube.com/watch?v=Fi1_1l7M8FA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They had to try really, &lt;strong&gt;really&lt;/strong&gt; hard to cause an explosive decompression, resorting to actual hollywood style explosives to make it happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airliners can actually even maintain normal pressurization even with a coffee can sized hole in the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as firing their weapon on board the aircraft, they are trained to not shoot towards areas like the cockpit or the floor where most of the &quot;important&quot; stuff is.  Avionics, hydraulic lines, electrical wiring, etc. don't take bullets well.  The rounds that they use would put holes in the aircraft, but as the above episode shows it won't create a pressurization problem.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-21T03:03:09.120" LastActivityDate="2014-03-21T03:03:09.120" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2528" PostTypeId="1" AcceptedAnswerId="2529" CreationDate="2014-03-21T03:45:08.140" Score="30" ViewCount="15537" Body="&lt;p&gt;On commercial flights, in part of the pre-flight safety demonstration, you're told in the event of a crash, not to inflate your life vest until you're outside the airplane &amp;mdash; why is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K6DPI.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2017-01-11T16:08:43.030" Title="Why shouldn't you inflate your life vest until you're outside the airplane?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;airliner&gt;&lt;ditching&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2529" PostTypeId="2" ParentId="2528" CreationDate="2014-03-21T03:45:08.140" Score="47" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961&quot; rel=&quot;noreferrer&quot;&gt;Ethiopian Airlines Flight 961&lt;/a&gt; was the flight that resulted in this addition to the safety briefing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After being hijacked, the plane eventually crash-landed in the ocean. Many passengers died because they inflated their life jackets in the cabin, causing them to be trapped inside by the rising water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mayday/Air Crash Investigation S03E13 (Ocean Landing) covered the incident. The relevant clip is here (from 23 seconds in):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/7a9VtnALUhk?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:05:11.650" LastActivityDate="2015-10-01T19:05:11.650" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2530" PostTypeId="1" AcceptedAnswerId="2535" CreationDate="2014-03-21T03:53:03.077" Score="15" ViewCount="8555" Body="&lt;p&gt;The news keeps talking about the black boxes on aircraft that end up in water, and one thing that keeps coming up is the underwater locator beacon that transmits a signal for 30 days if it gets wet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of signal does it transmit and what kind of range does it have?  I'm guessing that the depth of water that it is in will affect how far away that it can be detected, but by how much?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-27T18:41:04.630" Title="How close do you have to be to an underwater black box to detect it?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;search-and-rescue&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2531" PostTypeId="2" ParentId="615" CreationDate="2014-03-21T04:47:51.193" Score="17" Body="&lt;p&gt;As @voretaq7 says, getting tours of LAX of JFK towers just won't happen unless you happen to fly for an airline with a base there and/or are good at persuasion.  I've tried to negotiate a tower tour with the supervisor at LAX on short notice but he did indicate if I had a lot of lead time they might have been able to work something out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The easiest way to get a tour in my experience is just to call and ask for someone to talk to to request a tour.  I've been in the tower cab at EWR, AUS and CRG and in the Austin TRACON.  All of those were arranged with a phone call, a social security number and proof of citizenship (all post 9/11).  It helps to mention you  are a pilot and want to see how things work on their side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically the tower guys are going to want at least one of you to be a pilot and they'll want more lead time if you are bringing a group.  They'll also probably want to verify citizenship for everyone ahead of time and you'll want to be up front if you have an non-US people in the group just so they don't get surprised when you show up and they ask for passports or other ID.  Bring donuts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also toured the San Angelo, TX FSS.  For those guys I was already on field and just called the briefing number and asked if I could walk over.  They were happy to have us (I had a student with me).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a tour of any facility, just call.  They'll tell you what &lt;em&gt;they&lt;/em&gt; require and how and when the tour will happen and who you can bring. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-21T04:47:51.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2532" PostTypeId="1" AcceptedAnswerId="2542" CreationDate="2014-03-21T04:51:40.610" Score="13" ViewCount="8167" Body="&lt;p&gt;With all the searching on the surface of the Indian Ocean for evidence of Flt. 370, I'm wondering if there's any conceivable scenario in which the Boeing 777 could have sunk without producing any floating wreckage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible for a 777 or similar model to hit water without leaving a trace of remains on the surface?&lt;/p&gt;&#xA;" OwnerUserId="134" LastEditorUserId="97" LastEditDate="2014-03-21T05:13:41.963" LastActivityDate="2015-08-06T16:46:48.043" Title="Could Malaysia Airlines Flight 370 have sunk without leaving any floating wreckage?" Tags="&lt;accidents&gt;&lt;airliner&gt;&lt;search-and-rescue&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2533" PostTypeId="2" ParentId="1614" CreationDate="2014-03-21T05:39:05.377" Score="7" Body="&lt;p&gt;Since nobody's answered this yet, I'll take a stab at it.&lt;/p&gt;&#xA;&lt;p&gt;I tried to find some dimensions for you online, but struggled.&lt;/p&gt;&#xA;&lt;p&gt;Here's a thought though, could you just buy one?&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.concordecollectables.com/acatalog/Concorde_Engine_Blades.html&quot; rel=&quot;noreferrer&quot;&gt;For example&lt;/a&gt; - £35:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dHqzY.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This is a Rolls Royce Olympus 593 Turbojet engine High Pressure Compressor Vane. This is a flown item that powered BAs Concorde fleet and the blade shows signs of use.&lt;/p&gt;&#xA;&lt;p&gt;It was manufactured by Rolls Royce and has the Olympus 593 part number B430542.&lt;/p&gt;&#xA;&lt;p&gt;The dimensions of this item in centimetres are approximately 15.5 x 4 x 4 and it weighs approximately 400g.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There are &lt;a href=&quot;http://www.ebay.com/bhp/compressor-blade&quot; rel=&quot;noreferrer&quot;&gt;lots more&lt;/a&gt; on eBay too.&lt;/p&gt;&#xA;&lt;p&gt;You asked about material — &lt;a href=&quot;http://www.ebay.co.uk/itm/Aircraft-Jet-Engine-Rolls-Royce-RB199-Compressor-Blade-/260817984417&quot; rel=&quot;noreferrer&quot;&gt;one listing&lt;/a&gt; says the Tornado's Rolls Royce RB199 engine is made from titanium.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-21T06:29:23.233" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2534" PostTypeId="2" ParentId="2422" CreationDate="2014-03-21T05:43:45.803" Score="8" Body="&lt;p&gt;I'll take a stab at this one, though I can't guarantee the correctness of my interpretation (the regs don't seem exactly clear on the subject - at least not to me, so there's a lot more &quot;inference&quot; here than I'd normally be comfortable with).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases under Part 91 the only requirement to be a &quot;crewmember&quot; is that the pilot in command &lt;em&gt;says&lt;/em&gt; you're a crewmember -- i.e. the PIC determines that a person is qualified to perform a specific duty and designates them to perform it.&lt;br&gt;&#xA;In the absence of anything more specific this is the only requirement I can turn up (and it's an &lt;em&gt;inferred&lt;/em&gt; requirement - I didn't find anything specifically stating this, but &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=069887a24b6c23dd0133e8ca5de91277&amp;amp;n=14y2.0.1.3.10&amp;amp;r=PART&amp;amp;ty=HTML#14:2.0.1.3.10.6.7.17&quot;&gt;91.533 regarding flight attendants&lt;/a&gt; strongly implies that it's the correct interpretation. There's also a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2008/schehr%20-%20%282008%29%20legal%20interpretation.pdf&quot;&gt;counsel opinion from 2008 - the Schehr letter&lt;/a&gt; which talks a little about who is a &quot;crewmember&quot; for purposes of riding in jumpseats that are placarded &quot;For Crew Use Only&quot;. That interpretation is based on Part 135, but could be logically extended to Part 91 (and possibly some 121) operations too).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are frequently more specific requirements though, particularly for positions that are important to flight operations. For example if you buy yourself a nice shiny &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Model_10_Electra&quot;&gt;Lockheed Electra&lt;/a&gt; to duplicate Amelia Earhart's trip under Part 91 rules you still cannot simply designate someone off the street to be the Flight Navigator: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=75f90b5ca572c903e933e3c82e992e40&amp;amp;n=14y2.0.1.1.3.3&amp;amp;r=SUBPART&amp;amp;ty=HTML&quot;&gt;the FAA has specific requirements for Flight Navigator certification&lt;/a&gt;, and someone acting as the flight navigator would need to meet those requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also more stringent requirements that are imposed for Part 121 and 135 operators. For example they can't simply designate a person as a flight attendant based on the PIC's determination that they are qualified: There are requirements for filling that crew position which must be met (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=21fb07a52fe525ed3f52fde6d2d06a13&amp;amp;node=14:3.0.1.1.7.14.2.21&amp;amp;rgn=div8&quot;&gt;FAR 121.421&lt;/a&gt; &amp;amp; &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=45b18fc8c6ae093fb23d4440b2991477&amp;amp;node=14:3.0.1.1.11.7.3.3&amp;amp;rgn=div8&quot;&gt;FAR 135.295&lt;/a&gt; respectively, and possibly other regulations).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-21T15:29:47.823" LastActivityDate="2014-03-21T15:29:47.823" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2535" PostTypeId="2" ParentId="2530" CreationDate="2014-03-21T06:01:09.470" Score="14" Body="&lt;p&gt;This excellent explanation is taken from &lt;a href=&quot;http://www.aea.net/AvionicsNews/ANArchives/FlightDataRecordersJan06.pdf&quot; rel=&quot;noreferrer&quot;&gt;Avionics News&lt;/a&gt; in 2006:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FDRs are equipped with an Underwater Locator Beacon (ULB). If you look at a picture of an FDR, you will almost always see a small, cylindrical object attached to one end of the device.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KIE0Y.png&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;If a plane crashes into the water, this beacon sends out an ultrasonic pulse that cannot be heard by human ears but is readily detectable by sonar and acoustical locating equipment.&lt;/p&gt;&#xA;&lt;p&gt;There is a submergence sensor on the side of the beacon that looks like a bull's-eye. When water touches this sensor, it activates the beacon.&lt;/p&gt;&#xA;&lt;p&gt;The beacon sends out pulses at 37.5 kilohertz (kHz) and can transmit sound as deep as 14,000 feet (4,267 m). Once the beacon begins &amp;quot;pinging&amp;quot;, it pings once per second for 30 days.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_data_recorder#Design&quot; rel=&quot;noreferrer&quot;&gt;Newer FDRs&lt;/a&gt; can now transmit as deep as 20,000 ft.&lt;/p&gt;&#xA;&lt;p&gt;The following table is taken from &lt;a href=&quot;http://www.hydro-international.com/issues/articles/id1130-Deepwater_Black_Box_Retrieval.html&quot; rel=&quot;noreferrer&quot;&gt;a fascinatingly detailed article&lt;/a&gt; on Hydro International about the retrieval of black boxes. It shows the radius you can pick up the signal of a pinger from:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rc2sq.png&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Notice that if pingers were replaced with more powerful transponders, the range could be drastically improved!&lt;/p&gt;&#xA;&lt;p&gt;The article also points out, that in very deep water:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;under normal conditions, the existing pinger would not be detectable from the surface in depths exceeding 2km&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-27T14:46:12.547" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2536" PostTypeId="1" CreationDate="2014-03-21T06:29:05.427" Score="2" ViewCount="969" Body="&lt;p&gt;Without getting into the mess of redesigning existing Flight Data Recorders, I have a simple proposal that I think would help in deep water crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I propose that several floating cushion sets be distributed around the plane (tail section, along fuselage, etc.). These FDR floaties would be about the size of a seat cushion, but they'd be wrapped in a water soluble cover. When a plane crashes into the water, if the plane breaks up, then several of the cushions would float to the surface. When the cover dissolves, several folded arms open up making it much bigger exposing a orange-nylon covered mesh with an aluminum sheet embedded. This would be easier than seat cushions to see from satellites and planes, and the aluminum layer would reflect radar and make it easier to find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This alone would help find water crashes sooner, but if you add a simple USB memory stick in the center, then have data similar to the current FDR's being fed into it, then finding one of the floaties would give quite a bit of information including the final GPS coordinates before the crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These devices would be light and cheap. I'd think current planes could be retrofitted very cheaply. The only challenge would be the wiring needed to connect to the main FDR or the nearby data splitter. But just putting a few in the tail section alone would end this madness of having to find FDR's on the seabed to get a better idea of what happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't this be easy to implement without disturbing current FDR use and development? These would be destroyed in a fiery land crash, but that is not their purpose. This is just so we can find plane crashes in the sea when we don't know precisely where they went down (and to get basic data when the black boxes are too deep to get to immediately). Malaysian flight 370 and Air France Flight 447 would have both been greatly aided if these floaties were in those planes. What do you think?&lt;/p&gt;&#xA;" OwnerUserId="1674" LastEditorUserId="64" LastEditDate="2016-02-02T03:28:42.500" LastActivityDate="2016-02-02T03:28:42.500" Title="Black boxes: great for crashes on land. How about additional &quot;floaties&quot; for water crashes (low-tech, light, cheap)" Tags="&lt;flight-data-recorder&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-03-21T17:04:24.673" ContentLicense="CC BY-SA 3.0" />
  <row Id="2537" PostTypeId="2" ParentId="2115" CreationDate="2014-03-21T06:41:01.673" Score="3" Body="&lt;p&gt;Since no one else mentioned this, I thought I would. Wilbur Wright, of the Wright brothers, &lt;a href=&quot;http://books.google.co.jp/books?id=1OeCJFJY3ZYC&amp;amp;pg=PA237&amp;amp;lpg=PA237&amp;amp;dq=propeller%20%22twisted%20wing%22%20wilbur&amp;amp;source=bl&amp;amp;ots=WgJx020DFu&amp;amp;sig=Sc1ZGgWx05BzE-qpcLCCCt07RXg&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=7N0rU5S1LsqQlQXn8oGgBg&amp;amp;redir_esc=y#v=onepage&amp;amp;q=propeller%20%22twisted%20wing%22%20wilbur&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;said that&lt;/a&gt; a propeller was nothing more than a twisted wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you accept his analogy, then the twisted wings that compose a propeller are clearly &lt;em&gt;specialized&lt;/em&gt; wings, but they do generate a differential in air pressure above/in front of and below/behind as the surface moves through the air. That is what a wing does.&lt;/p&gt;&#xA;" OwnerUserId="1674" LastEditorUserId="97" LastEditDate="2014-03-21T07:11:19.447" LastActivityDate="2014-03-21T07:11:19.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2538" PostTypeId="1" AcceptedAnswerId="30719" CreationDate="2014-03-21T06:44:00.330" Score="16" ViewCount="11947" Body="&lt;p&gt;Are there any sites similar to &lt;a href=&quot;http://skyvector.com/&quot;&gt;SkyVector&lt;/a&gt; (US-based) for GA aviation maps in Australia? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that Air Services Australia has miscellaneous single-purposes &lt;a href=&quot;https://www.airservicesaustralia.com/aip/current/dap/AeroProcChartsTOC.htm&quot;&gt;maps available&lt;/a&gt;, but they seem to be mostly airport diagrams and approach procedures. I'm looking for GA VFR maps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the only thing available is SkyVector's world maps (&lt;a href=&quot;http://skyvector.com/?ll=-37.73748966062555,145.2159118537511&amp;amp;chart=301&amp;amp;zoom=4&quot;&gt;of Australia&lt;/a&gt;), how accurate are they?&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="97" LastEditDate="2014-03-21T07:08:20.790" LastActivityDate="2020-04-13T19:00:56.963" Title="Where can I find GA VFR maps for Australia?" Tags="&lt;general-aviation&gt;&lt;visual-flight-rules&gt;&lt;aeronautical-charts&gt;&lt;website&gt;&lt;australia&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2539" PostTypeId="2" ParentId="1755" CreationDate="2014-03-21T06:48:54.207" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/innovation/proven-concepts/in-design/winglets/&quot;&gt;Airbus says&lt;/a&gt; this about their new &lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device#Blended_winglets&quot;&gt;blended winglets&lt;/a&gt; (aka &quot;Sharklets&quot;), being fitted to new A320s, and retrofitted:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus’ next step is the large Sharklets™ wingtip devices, representing another element in the ongoing continuous improvement programme for its best-selling A320 Family. These devices improve aerodynamics, &lt;strong&gt;reducing fuel burn by up to 4 per cent&lt;/strong&gt; – which amounts to annual savings of more than 900 tonnes of CO2 per aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Given that an A320's fuel burn rate is approximately 5.13 gallons per seat per hour, reducing this by 4% gives you 4.92 gallons/seat/hr.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparatively, a 737-800 burns about 4.88 gallons/seat/hr.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bizjournals.com/seattle/stories/2008/08/11/story13.html?page=all&quot;&gt;Source&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A 737-800 burns 4.88 gallons of fuel per seat per hour, compared with the comparable A320's burn of 5.13 gallons per seat per hour, according to The Airline Monitor, an industry publication.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So they're near enough the same.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-21T07:29:07.790" LastActivityDate="2014-03-21T07:29:07.790" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2540" PostTypeId="2" ParentId="2536" CreationDate="2014-03-21T07:08:16.077" Score="6" Body="&lt;p&gt;The first thing that comes to mind to me is that they'd have to be firmly attached enough to not come off in flight, yet somehow detach easily when in the water. They'd also create additional drag, which - especially to commercial air carriers - translates to money lost (additional fuel). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There would also need to be some connection (wired or wireless) to continuously transmit data to them (I'm assuming that you're proposing several of them). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the whole point of the FDR's housing is that it's rigid enough to withstand explosions and impact, yet the floatation proposal requires that there be some sort of expanding material that'd inflate upon contact (or presumably submersion - consider weather/rain) with water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;General aviation aircraft use ELTs (&lt;a href=&quot;http://en.wikipedia.org/wiki/Emergency_Locator_Transmitter&quot; rel=&quot;nofollow&quot;&gt;Emergency Locator Transmitters&lt;/a&gt;), which are designed just to notify of the location of a crash incident. They are required in the U.S. for general aviation and commercial aircraft, but unfortunately not for scheduled &lt;a href=&quot;http://www.ntsb.gov/news/events/2012/GA_Search_Rescue/presentations/Smith.pdf&quot; rel=&quot;nofollow&quot;&gt;flights by an air carriers&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I get the impression that the trend is probably towards having more data transmitted real-time during the flight (think &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447#Automated_messages&quot; rel=&quot;nofollow&quot;&gt;Air France stall/crash&lt;/a&gt;) of systems monitoring data and location such that location and recovery of more data-intensive logs (voice recorder) would be more efficient.&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2014-03-22T06:30:51.943" LastActivityDate="2014-03-22T06:30:51.943" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2541" PostTypeId="2" ParentId="2528" CreationDate="2014-03-21T08:24:29.680" Score="28" Body="&lt;p&gt;In addition to the risk of being trapped mentioned by Danny Beckett, the overwing exits are small.  If you inflate your vest before exiting, you'll have a harder time getting out, and you're more likely to tear the vest.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-03-21T08:24:29.680" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2542" PostTypeId="2" ParentId="2532" CreationDate="2014-03-21T08:43:13.567" Score="11" Body="&lt;p&gt;Yes, but only under highly unlikely circumstances.  An airplane contains all sorts of materials that float, from fuel to seat cushions to the plastic cups in the galley.  In order to sink without leaving any floating wreckage, &lt;em&gt;all&lt;/em&gt; of that material would need to be trapped within the airplane while it fills with water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for this to happen, the airplane needs to land intact on the water.  As any number of ditchings indicate, this isn't going to happen -- even US Airways 1549 had the rear of the fuselage tear open on landing.  More often, the engines or wings will tear off, leaving oil and fuel slicks.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-03-21T08:43:13.567" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2543" PostTypeId="2" ParentId="2532" CreationDate="2014-03-21T10:12:54.167" Score="3" Body="&lt;p&gt;Yes, it's certainly possible. But it all depends on a lot of factors.&lt;br/&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Speed of impact. Obviously, the lower the speed of impact the fewer pieces will break away.&lt;/li&gt;&#xA;&lt;li&gt;time. Even if things break away and float, after a while they'll sink as they become water logged. And that may only take minutes.&lt;/li&gt;&#xA;&lt;li&gt;environmental conditions. Water temperature affects the speed at which chemical spills dissipate. So do wind and currents. Wind and currents, through wave action, can also break up into tiny fragments and cause to sink any floating debris.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So even if something were left on the surface after the impact, after a few hours most of it would be gone. After days, unless the aircraft crashed near a shore and pieces wash up, most likely there's nothing left to see unless very large pieces broke off and managed to stay afloat (which would require very calm surface conditions indeed).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-21T10:12:54.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2546" PostTypeId="2" ParentId="2482" CreationDate="2014-03-21T13:12:13.650" Score="4" Body="&lt;p&gt;It is common procedure to skydive from airplanes in distress, if the plane is already on it's way to altitude, carrying skydivers. There are parameters to consider though. When you are a trained skydiver, the safest option might be to get people out, because landing a plane with an engine failure is easier with a light load. This of course depends on altitude, and maybe surrounding options or landing a parachute (forests, mountains or relatively deep water would be bad).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have done this once, when one of the engines of a twin otter went out at 9000 feet. This is also the reason why skydivers are ALWAYS required to wear their gear fully fastened while in the aircraft. In an emergency, even trained skydivers might not have time, space or stability enough to put on gear properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And by gear i mean the parachute, and it's straps. Not necessarily the helmet etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For untrained, and/or people not already wearing the harness, I would assume that it is safer to try to land with the aircraft, If in a situation where getting out is at all possible.&lt;/p&gt;&#xA;" OwnerUserId="1689" LastActivityDate="2014-03-21T13:12:13.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2548" PostTypeId="1" CreationDate="2014-03-21T15:38:26.317" Score="1" ViewCount="48" Body="&lt;p&gt;I can see many airplanes circling around to land at KORD. I am wondering if there is a good real-time website or application to track these planes with 30-second accuracy or better. Any ideas? &lt;/p&gt;&#xA;" OwnerUserId="1692" LastActivityDate="2014-03-21T15:38:26.317" Title="Is there a good iPhone app for tracking commercial aircraft?" Tags="&lt;landing&gt;&lt;commercial-aviation&gt;&lt;traffic-pattern&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2014-03-21T16:04:27.960" ContentLicense="CC BY-SA 3.0" />
  <row Id="2549" PostTypeId="1" AcceptedAnswerId="2551" CreationDate="2014-03-21T07:54:04.697" Score="45" ViewCount="73828" Body="&lt;p&gt;Why does it take longer to fly East to West than West to East?&lt;/p&gt;&#xA;&lt;p&gt;Which factors affect this?&lt;/p&gt;&#xA;&lt;p&gt;Does Earth's spinning affect the time difference? Maybe the air circulation?&lt;/p&gt;&#xA;" OwnerUserId="1709" OwnerDisplayName="Yadav Chetan" LastEditorUserId="53014" LastEditDate="2020-12-24T06:10:01.137" LastActivityDate="2020-12-24T06:10:01.137" Title="Why do flight times differ between traveling East versus traveling West?" Tags="&lt;airline-operations&gt;&lt;winds-aloft&gt;" AnswerCount="8" CommentCount="4" FavoriteCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="2550" PostTypeId="2" ParentId="2549" CreationDate="2014-03-21T08:47:26.790" Score="16" Body="&lt;p&gt;The main reason for the difference in time are &lt;a href=&quot;http://en.wikipedia.org/wiki/Trade_wind&quot;&gt;&lt;em&gt;trade winds&lt;/em&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trade winds generally travel East to West, and so aircraft travelling in this direction have a faster &lt;em&gt;ground speed&lt;/em&gt;, that is the speed relative to the ground. The &lt;em&gt;true air speed&lt;/em&gt; of any aircraft is not affected by the wind. &lt;/p&gt;&#xA;" OwnerDisplayName="Robbie" LastActivityDate="2014-03-21T11:44:07.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2551" PostTypeId="2" ParentId="2549" CreationDate="2014-03-21T16:18:14.057" Score="35" Body="&lt;p&gt;As Robbie's answer implies, the answer is wind - Trade Winds govern what happens on or near the surface and were historically important for sailing ships, and today in aviation we deal with the &lt;a href=&quot;http://aviationweather.gov/adds/winds/&quot; rel=&quot;noreferrer&quot;&gt;the Winds Aloft&lt;/a&gt; at whatever altitude your plane is flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, consider two hypothetical flights at 30,000 feet with the winds shown below:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6p4B1.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6p4B1m.gif&quot; alt=&quot;Winds Aloft at 30,000 ft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With these winds a flight from A to B (East-to-West) will be fighting headwinds the whole way. My handy flight planning program tells me that at 500 knots (airspeed) you'd be in the air for about 5 hours 30 minutes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Traveling in the opposite direction from B to A you'd have a tailwind, and with the same 500 knot airspeed you would make the trip in roughly 4 hours.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The winds aloft vary seasonally, which can affect flight times for summer versus winter trips. &lt;a href=&quot;http://chat.stackexchange.com/rooms/12036/conversation/winds-aloft-q2549&quot;&gt;According to one of our folks who is regularly up at those altitudes&lt;/a&gt; even the daily variations can be noticeable, and may make the difference between being able to make a nonstop trip or having to stop for fuel on the way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots and flight dispatchers will often review the wind data prior to flight and try to select an altitude that affords a &quot;good ride&quot; (free of turbulence) and favorable winds (either a tailwind or the lowest headwind they can find).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-21T16:26:47.097" LastActivityDate="2014-03-21T16:26:47.097" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2552" PostTypeId="2" ParentId="2549" CreationDate="2014-03-21T18:47:57.843" Score="4" Body="&lt;p&gt;The jet stream moves from West to East. At the altitude an airliner flies the speed of the tail wind or head wind will have a significant impact on actual ground speed. This was first observed when B-29 bombing raids on Japan during WW2. Before that there was no notion of a 'jet stream'.&lt;/p&gt;&#xA;" OwnerUserId="1698" LastEditorUserId="1702" LastEditDate="2014-03-21T21:57:38.653" LastActivityDate="2014-03-21T21:57:38.653" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2554" PostTypeId="1" AcceptedAnswerId="2587" CreationDate="2014-03-21T20:34:36.267" Score="22" ViewCount="2470" Body="&lt;p&gt;I'm not a pilot, so I always wonder when I'm flying why does it happen... Is it because of bad weather, or something else?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="97" LastEditDate="2014-03-22T02:43:54.670" LastActivityDate="2014-03-23T13:08:23.917" Title="What is turbulence, and how does it happen?" Tags="&lt;weather&gt;&lt;turbulence&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2555" PostTypeId="1" AcceptedAnswerId="2557" CreationDate="2014-03-21T20:45:32.187" Score="20" ViewCount="2773" Body="&lt;p&gt;At some early stage in the flight, why will commercial pilots announce the cruising altitude of the flight?  &lt;/p&gt;&#xA;" OwnerUserId="1701" LastEditorUserId="1696" LastEditDate="2015-02-16T16:16:01.930" LastActivityDate="2015-02-16T19:12:19.250" Title="Why do pilots announce the cruising altitude of a flight?" Tags="&lt;passenger&gt;&lt;pilots&gt;&lt;cruise&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2556" PostTypeId="2" ParentId="2554" CreationDate="2014-03-21T20:58:29.037" Score="21" Body="&lt;p&gt;Air turbulence is very much the same as the currents of a river.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a parcel or stream of air moves differently than the area around it, you get turbulence as you transition between them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example would be if you are outside on a windy day but stand behind a tree to &quot;get out of the wind&quot;.  If you step out from behind the tree, you will feel a sudden &quot;jolt&quot; as the wind hits you.  If it's a particularly strong wind, it could even cause you to lose your balance for a second until you compensate for it.  Well, these invisible air currents affect an aircraft in much the same way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It isn't normally dangerous, and I think of it like driving down a bumpy road.  Of course, it's usually even safer in an airplane because even if you hit a big &quot;pothole&quot; you don't have to worry about it throwing you off the road into a tree.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual movement of the air can be caused by several things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind hitting something (like a building or a mountain) and displacing it (just like rocks in a river).&lt;/li&gt;&#xA;&lt;li&gt;Air being heated by the ground which then causes it to rise.&lt;/li&gt;&#xA;&lt;li&gt;Weather activity like fronts, thunderstorms, or jetstreams.&lt;/li&gt;&#xA;&lt;li&gt;An aircraft moving through the air will cause turbulence of its own (known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake_turbulence&quot;&gt;wake turbulence&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="64" LastEditDate="2014-03-21T21:28:03.670" LastActivityDate="2014-03-21T21:28:03.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2557" PostTypeId="2" ParentId="2555" CreationDate="2014-03-21T21:00:39.773" Score="24" Body="&lt;p&gt;No real reason other than it keeps people from bugging the flight attendants by asking &quot;how high are we??&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also lets the flight attendants know that the aircraft is at cruise so won't be climbing and making the carts harder for them to push around. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-21T21:00:39.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2558" PostTypeId="2" ParentId="2555" CreationDate="2014-03-21T21:13:10.013" Score="6" Body="&lt;p&gt;If it is at the beginning of the flight, I would guess they are just sharing in case any passengers are interested.&#xA;It may give flight attendants an idea of how long it will take to reach cruise.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-21T21:13:10.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2559" PostTypeId="2" ParentId="1743" CreationDate="2014-03-21T22:34:16.100" Score="7" Body="&lt;p&gt;Generally the airlines operating procedures will only permit IFR operation.&#xA;Occasionally non-revenue flights for aircraft positioning etc, will operate VFR for expediency.&#xA;I know of one pilot who has delivered old airliners to the Mojave boneyard on a VFR flight from LAX.&lt;/p&gt;&#xA;" OwnerUserId="1704" LastActivityDate="2014-03-21T22:34:16.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2560" PostTypeId="1" AcceptedAnswerId="2562" CreationDate="2014-03-21T22:57:06.743" Score="18" ViewCount="2394" Body="&lt;p&gt;I was watching an episode of &lt;a href=&quot;http://en.wikipedia.org/wiki/MythBusters_%282009_season%29#Sonic_Boom_Sound-off&quot;&gt;MythBusters&lt;/a&gt; where they were trying to break glass windows and cups using a sonic boom generated by a &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot;&gt;F/A-18 Hornet&lt;/a&gt;, flown by the &lt;a href=&quot;http://en.wikipedia.org/wiki/Blue_Angels&quot;&gt;Blue Angels&lt;/a&gt;.  In summary, they were unsuccessful at creating a boom that could shatter the windows, despite a mach speed pass within 200ft of the target building. In the last two passes they even flew straight at the building to focus the boom straight at the house, still no windows were shattered. **&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I've wondered, ever since, if they were unsuccessful because the plane was simply too small.  What if the sonic boom had been generated by a &lt;a href=&quot;http://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot;&gt;B-1 Lancer&lt;/a&gt; or perhaps Concorde, which are several times larger than the F/A-18?  Logically it seems that since you are displacing more air, the energy wave should have more energy.  Then again, the plane isn't going any faster, so perhaps the surface area of the wave would be larger (because of the larger plane) but you wouldn't actually have any more energy at any given point?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone know if a bigger plan than the F/A-18 would have a higher energy sonic boom?  And could that cause glass to break?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus point:&#xA;A mathematical formula showing why, I love those things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;For those curious about what a sonic boom is to begin with, here's a &lt;a href=&quot;http://en.wikipedia.org/wiki/Sonic_boom&quot;&gt;wikipedia article&lt;/a&gt;&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;**Just to clarify, for those who have seen the episode.  A window &lt;em&gt;is&lt;/em&gt; broken during the 200ft pass but they say that it only happened because the frame warped, not because the glass itself shattered.  Their reasoning is that only that one window broke (out of several windows and glass cups in the area), and it had a pretty cheap frame on it.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-03-22T03:27:47.210" LastActivityDate="2014-03-22T03:48:52.180" Title="Do bigger aircraft make a bigger sonic boom?" Tags="&lt;supersonic&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2561" PostTypeId="1" AcceptedAnswerId="2563" CreationDate="2014-03-22T01:33:15.640" Score="17" ViewCount="8350" Body="&lt;p&gt;There are two sides I've heard when taking off in a Cessna 182 or other small airplane with a normally aspirated engine driving a constant speed propeller:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;As soon as your wheels are off the ground... Or,&lt;/li&gt;&#xA;  &lt;li&gt;When you're 700-1,000 feet off the ground...&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;Reduce to about 23&quot; of manifold pressure and then reduce the RPM to 2,450 (or 2,300) depending on the plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The POH or Owner's Manual (in my case a 1972 Cessna 182P) simply says Full Power under the Normal Take-Off procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasoning I've heard is to try not to over-stress the engine (whatever that means exactly), but on the flip side, I've heard that if an engine is going to do something funky, it's probably going to happen when you do a power reduction, or otherwise do &lt;em&gt;something&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I personally want all the power I can have until I'm far enough off the ground to have options if the engine quits or sputters (turn back if high enough, or glide to a suitable spot if not).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking is there an &quot;official procedure&quot; as to when you should perform this power reduction (inches off the ground or 700-1,000 feet), and if so, have there been actual studies that say why one way is better than the other, or is this one of those groundless, &quot;endless debates&quot; that are so prevalent in aviation?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="97" LastEditDate="2014-03-22T03:25:42.513" LastActivityDate="2021-01-05T03:50:52.433" Title="When to reduce power on takeoff (Cessna 182 or similar)?" Tags="&lt;piston-engine&gt;&lt;takeoff&gt;&lt;pilot-technique&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2562" PostTypeId="2" ParentId="2560" CreationDate="2014-03-22T02:46:35.600" Score="16" Body="&lt;p&gt;The short version is that yes, larger aircraft create bigger sonic booms, but you still have to be flying very low (less than 100 ft.) and really trying hard in order to damage glass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A sonic boom is so complicated that you will not find a simple formula to determine the strength.  &lt;a href=&quot;http://proceedings.esri.com/library/userconf/proc01/professional/papers/pap284/p284.htm&quot;&gt;This article&lt;/a&gt; describes a modeling tool called PCBoom3 which can be used for sonic boom calculations.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;According to several different sites, like &lt;a href=&quot;http://www.alamogordoforum.com/sonic_booms.htm&quot;&gt;this one&lt;/a&gt; and &lt;a href=&quot;http://library.thinkquest.org/12228/Page3.html&quot;&gt;this one&lt;/a&gt;, the size of the aircraft does affect the intensity:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h1&gt;Factors Affecting Sonic Boom Intensity&lt;/h1&gt;&#xA;  &#xA;  &lt;p&gt;The intensity of sonic booms are affected by:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Weight, size and shape of the aircraft.&lt;/li&gt;&#xA;  &lt;li&gt;Altitude&lt;/li&gt;&#xA;  &lt;li&gt;Attitude—orientation of the aircraft’s axes relative to the its direction of motion.&lt;/li&gt;&#xA;  &lt;li&gt;Flight path.&lt;/li&gt;&#xA;  &lt;li&gt;Atmospheric and weather conditions.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;As the size and weight of the aircraft increases, the intensity of the&#xA;  sonic increases. This is because a larger aircraft displaces more air,&#xA;  and a heavier aircraft needs a greater force of lift to sustain&#xA;  flight. Thus creating a louder and stronger sonic boom.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h1&gt;General Factors Associated With Sonic Booms&lt;/h1&gt;&#xA;  &#xA;  &lt;p&gt;There are several factors&#xA;  that can influence sonic booms -- weight, size, and shape of the&#xA;  aircraft or vehicle, plus its altitude, attitude and flight path, and&#xA;  weather or atmospheric conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A larger and heavier aircraft must displace more air and create more&#xA;  lift to sustain flight, compared with small, light aircraft.&#xA;  Therefore, they will create sonic booms stronger and louder than those&#xA;  of smaller, lighter aircraft. The larger and heavier the aircraft, the&#xA;  stronger the shock waves will be.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/dryden/Features/WSPR_research_complete.html#.Uyz1t61dXuE&quot;&gt;NASA&lt;/a&gt; says that a typical sonic boom for the F/A-18 is about 1.4 psf and a &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-016-DFRC.html#.Uyz2TK1dXuE&quot;&gt;different NASA page&lt;/a&gt; goes on to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Overpressure Sonic booms are measured in pounds per square foot of&#xA;  overpressure. This is the amount of the increase over the normal&#xA;  atmospheric pressure which surrounds us (2,116 psf/14.7 psi).  At one&#xA;  pound overpressure, no damage to structures would be expected.&#xA;  Overpressures of 1 to 2 pounds are produced by supersonic aircraft&#xA;  flying at normal operating altitudes. Some public reaction could be&#xA;  expected between 1.5 and 2 lb.  Rare minor damage may occur with 2 to&#xA;  5 lb overpressure.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As overpressure increases, the likelihood of structural damage and&#xA;  stronger public reaction also increases. Tests, however, have shown&#xA;  that structures in good condition have been undamaged by overpressures&#xA;  of up to 11 lb.  Sonic booms produced by aircraft flying supersonic at&#xA;  altitudes of less than 100 feet, creating between 20 and 144 lb&#xA;  overpressure, have been experienced by humans without injury.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Damage to eardrums can be expected when overpressures reach 720 lb.&#xA;  Overpressures of 2160 lb would have to be generated to produce lung&#xA;  damage.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Typical overpressure of aircraft types are:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;SR-71: 0.9 lb, speed of Mach 3, 80,000 feet&lt;/li&gt;&#xA;  &lt;li&gt;Concorde SST: 1.94 lb, speed of Mach 2, 52,000 feet&lt;/li&gt;&#xA;  &lt;li&gt;F-104: 0.8 lb, speed of Mach 1.93, 48,000 feet&lt;/li&gt;&#xA;  &lt;li&gt;Space Shuttle: 1.25 lb, speed of Mach 1.5, 60,000 feet, landing approach&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also include a graphic that shows the difference in sonic boom between the F-18 and the Concorde, with the Concorde having a much greater sonic boom at the same alittude:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/351gC.jpg&quot; alt=&quot;Sonic Boom Plots&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/684806.pdf&quot;&gt;This article&lt;/a&gt; specifically covers glass:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Glass&lt;/strong&gt;. Poorly mounted, undamaged glass in the greenhouse was chipped&#xA;  by impact against nail holding points at a sonic boom overpressure of&#xA;  12.1 psf. The same type of glass, which was already damaged, was further damaged at a designed overpressure of 7.9 psf. A large&#xA;  one-ninth of an inch thick window, intentionally precracked from&#xA;  corner to corner, was further damaged by booms of an average 6.5 psf&#xA;  overpressure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So typical sonic booms generated by normal aircraft aren't going to create anywhere close to the 12.1 psf that they say is needed to chip &quot;poorly mounted&quot; glass, but the strongest sonic booms can get well over this.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-22T03:48:52.180" LastActivityDate="2014-03-22T03:48:52.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2563" PostTypeId="2" ParentId="2561" CreationDate="2014-03-22T03:11:30.593" Score="13" Body="&lt;p&gt;The &quot;official procedure&quot; is the one dictated in your aircraft's POH/AFM.&lt;br&gt;&#xA;Within the leeway that document gives you (and many of them give you &lt;em&gt;a lot of leeway&lt;/em&gt;) this is definitely one of those &quot;endless debate&quot; subjects.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Personally in a single-engine piston aircraft unless the POH directs otherwise or operational considerations (like an altitude restriction from ATC) require something different I would maintain full power (and all other takeoff settings - fuel pumps, etc.) until reaching 1000-1500 feet AGL (depending on what the terrain and obstacles in the area are like), then configure the aircraft for a reduced-power cruise climb if appropriate.&lt;br&gt;&#xA;Whether or not the first power reduction is a time of increased failure is irrelevant to me - I operate on the assumption that &lt;em&gt;the engine can fail at any time&lt;/em&gt;, and should the engine fail (for whatever reason) I want adequate distance between myself and the ground to make some decisions, confirm my landing spot, and prepare myself, my passengers, and the aircraft for whatever is going to happen next.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1000 feet AGL is &lt;em&gt;my&lt;/em&gt; minimum threshold for that sort of activity. It's possible (maybe even likely) that I'm imposing additional wear on the engine in requiring full power for this long, but if the engine decides to fail on climb-out it's not going to matter how &quot;nice&quot; I was being to it on all my previous flights - the only things that are going to matter are my altitude, airspeed, and landing options, and I'm going to want as much altitude and airspeed as I can get to help maximize my landing options!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are some conditions where I would reduce power sooner than 1000 feet AGL if necessary - for example, if I can't maintain oil or cylinder head temperatures &quot;in the green&quot; in a full power climb a power reduction (or pitch reduction) to keep those engine parameters happy would be in order.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some aircraft/engines which have a continuous power restriction (&lt;code&gt;Full throttle operation limited to 3 minutes&lt;/code&gt;,  &lt;code&gt;maximum continuous power 2400 RPM&lt;/code&gt;, or similar admonitions you'd find in your POH). In those cases the restrictions should obviously be observed (the engineers who set the limitations had a good reason for doing so), and observing those requirements may necessitate a power reduction or other configuration changes prior to reaching 1000 feet AGL.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Finally, I'm not sure what kind of engine is in your hypothetical Cessna but as an additional point of reference Lycoming has this to say about takeoff operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;Operating Your Lycoming Engines At Takeoff And Climb&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;Because there are&#xA;  a wide variety of Lycoming engines in operation, the paragraphs below&#xA;  may be helpful in understanding the different modes of operation&#xA;  required when operating each type at takeoff and climb power settings.&#xA;  The Pilots Operating Handbook for the aircraft in which the engines&#xA;  are installed should be the final authority as to how the engine&#xA;  should be operated. &lt;/p&gt;&#xA;  &#xA;  &lt;h3&gt;DIRECT DRIVE ENGINES&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;Most normally aspirated&#xA;  engines are rated at full power for takeoff and climb indefinitely,&#xA;  provided engine temperatures and pressures are within the green arc&#xA;  area of the engine instruments. Extra fuel, sensible airspeed, and&#xA;  cowl flaps, if available, are all helpful in keeping cylinder head&#xA;  temperatures within desired limits during takeoff or climb.&lt;br&gt;&#xA;  Climb&#xA;  requirements may vary; as an example, on a warm day with the airplane&#xA;  close to gross weight, and a direct drive engine with a fixed pitch&#xA;  prop, the pilot will need full throttle all the way to cruise&#xA;  altitude. The same airplane on a cold day and lightly loaded may not&#xA;  require full power for climb. After full throttle at takeoff, the&#xA;  pilot may want to reduce power 100 or 200 RPM and still not see&#xA;  performance suffer. Those direct drive normally aspirated engines with&#xA;  a prop governor are also rated indefinitely at full power, and the&#xA;  manuals all recommend full power for takeoff, but specify a small&#xA;  reduction in power, generally to 85% power climb. Study the specific&#xA;  airplane Pilot's Operating Handbook for detailed power settings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(They go on to talk about geared engines and turbocharged/supercharged engines, but your question was about normally-aspirated engines. This is from Lycoming Flyer &quot;Key Reprints&quot; - I grabbed it &lt;a href=&quot;http://djholman.csde.washington.edu/Yankee/Lycoming/LycomingKeyReprints.pdf&quot;&gt;here&lt;/a&gt; but you can Google it up pretty easily, and I imagine Continental has analogous guidance somewhere.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-22T03:19:56.117" LastActivityDate="2014-03-22T03:19:56.117" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2565" PostTypeId="1" AcceptedAnswerId="2615" CreationDate="2014-03-22T12:45:09.693" Score="4" ViewCount="505" Body="&lt;p&gt;In Australia, aircraft approved for ASETPA operations are certain single-engine turbines allowed to be operated commercially under IFR. While I understand that the manufacturer is required to meet a series of requirement, I'm not so sure about whether the pilots in ASETPA operations need special training or approval. Is extra training and/or testing required, and if so, how extensive is it?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-03-24T02:47:42.160" Title="What training is required for pilots conducting ASETPA operations?" Tags="&lt;casa-regulations&gt;&lt;australia&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2566" PostTypeId="1" AcceptedAnswerId="2582" CreationDate="2014-03-22T14:49:21.720" Score="24" ViewCount="40262" Body="&lt;p&gt;I saw &lt;a href=&quot;https://history.stackexchange.com/q/12089&quot;&gt;this question&lt;/a&gt; from History Stack Exchange and noted that the US is still using the imperial measurement system such as feet, miles and pounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that a plane may need to fly from one country to another, is there any standardisation across the globe? Does planes manufactured by Boeing use one system and planes made by the Airbus another system? If not, wouldn't it be very easy for pilots to make calculation error?&lt;/p&gt;&#xA;" OwnerUserId="1390" LastEditorUserId="-1" LastEditDate="2017-04-13T12:47:54.013" LastActivityDate="2018-07-04T20:52:17.407" Title="What is the measurement system used in the aviation industry?" Tags="&lt;commercial-aviation&gt;&lt;measurement&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2567" PostTypeId="1" AcceptedAnswerId="2569" CreationDate="2014-03-22T15:00:21.067" Score="8" ViewCount="3601" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;An &lt;strong&gt;autobrake&lt;/strong&gt; is a type of automatic wheel-based hydraulic brake system for advanced airplanes. The autobrake is &lt;strong&gt;normally enabled during takeoff and landing&lt;/strong&gt; procedures, when the aircraft's longitudinal deceleration system can be handled by the automated systems of the aircraft itself in order to keep the pilot free to perform other tasks - &lt;a href=&quot;http://en.wikipedia.org/wiki/Autobrake&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;How does the aircraft &quot;know&quot; when is time to activate the autobrake&#xA;systems on a rejected takeoff and landing?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does it apply full brake to all the aircraft's wheels?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it really used by commercial jets?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="97" LastEditDate="2014-03-22T15:12:47.473" LastActivityDate="2014-03-22T15:23:16.527" Title="How does autobrake work?" Tags="&lt;landing&gt;&lt;airliner&gt;&lt;takeoff&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2568" PostTypeId="2" ParentId="2566" CreationDate="2014-03-22T15:07:13.887" Score="10" Body="&lt;p&gt;I can tell you that all of the airplanes that I have flown (which are US registered, but some are French built) use the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Feet for height&lt;/li&gt;&#xA;&lt;li&gt;Knots for airspeed (Nautical Miles/Hour)&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some &lt;strong&gt;old&lt;/strong&gt; airplanes still use Miles/Hour (MPH)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Nautical Miles or feet for distance&lt;/li&gt;&#xA;&lt;li&gt;Statue Miles or feet for weather (visibility and RVR)&lt;/li&gt;&#xA;&lt;li&gt;Mach for high speed flight&lt;/li&gt;&#xA;&lt;li&gt;Inches of Mercury for altimeter settings&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most of the airplanes that I have flown can actually switch between &quot;hg and hPa (mb).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;pounds/square inch for pressure&lt;/li&gt;&#xA;&lt;li&gt;Pounds for the fuel quantity on the aircraft (read by the fuel gauges)&lt;/li&gt;&#xA;&lt;li&gt;Pounds/hour for fuel flow&lt;/li&gt;&#xA;&lt;li&gt;Gallons to order/purchase fuel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are pretty standard in most of the Americas (North/Central/South), but in certain parts of the world some of the units are different:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Meters for height&lt;/li&gt;&#xA;&lt;li&gt;Kilometers or meters for distance and weather&lt;/li&gt;&#xA;&lt;li&gt;HectoPascals (hPa/Millibars) for altimeter settings&lt;/li&gt;&#xA;&lt;li&gt;Kilograms for fuel quantity on the aircraft&lt;/li&gt;&#xA;&lt;li&gt;Kilograms/hour for fuel flow&lt;/li&gt;&#xA;&lt;li&gt;Liters to order/purchase fuel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-22T22:32:40.293" LastActivityDate="2014-03-22T22:32:40.293" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2569" PostTypeId="2" ParentId="2567" CreationDate="2014-03-22T15:23:16.527" Score="9" Body="&lt;p&gt;Not all commercial jets have autobrakes, and the ones that do usually have a company policy dictating when it will be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The criteria for activating the brakes are different depending on the manufacturer and model of aircraft, but are typically some combination of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;System must be armed&lt;/li&gt;&#xA;&lt;li&gt;A certain takeoff power setting must be set by the throttles&lt;/li&gt;&#xA;&lt;li&gt;A certain airspeed must be obtained&lt;/li&gt;&#xA;&lt;li&gt;Thrust levers must be pulled back to idle&lt;/li&gt;&#xA;&lt;li&gt;Aircraft must still be on the ground&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Usually for a rejected takeoff it does use max braking, however the autobrake usually has different settings for landing along the lines of &quot;light/medium/max&quot; braking.  Each setting will use a different amount of runway for landing, much like lightly pressing on the brake pedal in your car versus jamming it to the floor.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-22T15:23:16.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2570" PostTypeId="1" AcceptedAnswerId="2578" CreationDate="2014-03-22T15:43:35.860" Score="19" ViewCount="9990" Body="&lt;p&gt;I was watching the Disney movie &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Planes_%28film%29&quot;&gt;Planes&lt;/a&gt;&lt;/em&gt; with my younger brother, and one of the characters/planes perform a emergency landing on an aircraft carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that got me thinking...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of &lt;strong&gt;emergency&lt;/strong&gt;, is it possible (&lt;strong&gt;doable&lt;/strong&gt;) to land a &lt;strong&gt;small propeller-driven aircraft&lt;/strong&gt;, like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_350&quot;&gt;Cessna 350 Corvalis&lt;/a&gt; on a military &lt;strong&gt;aircraft carrier&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="7532" LastEditDate="2015-12-16T00:26:32.097" LastActivityDate="2017-07-01T03:38:34.687" Title="In case of emergency, is it possible (doable) to land a small propeller-driven aircraft on an aircraft carrier?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;propeller&gt;&lt;aircraft-carrier&gt;" AnswerCount="9" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2571" PostTypeId="1" AcceptedAnswerId="2579" CreationDate="2014-03-22T15:56:46.423" Score="8" ViewCount="2506" Body="&lt;p&gt;As a follow up to &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2566/what-is-the-measurement-system-used-in-the-aviation-industry&quot;&gt;What is the measurement system used in the aviation industry?&lt;/a&gt;&quot; which specified about measurement units during operations, another question that comes to my mind is: are there differences used in tools for maintenance and repairs for aircraft produced in different countries?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although things have been standardized these days, in the automotive industry you still get differences in the types of tools that are required for repairs. For example, the old British cars such as Land Rover or MG used imperial spanners until not long ago (3/8, 5/16 etc) whereas other cars used more common metric spanners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this apply also to aircraft? An example that comes into my mind would be the Avro RJ series.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-02-16T18:53:36.777" Title="Are there differences in tool standards between aircraft manufacturers?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2572" PostTypeId="1" CreationDate="2014-03-22T16:54:10.103" Score="27" ViewCount="11517" Body="&lt;p&gt;This is a followup to &lt;a href=&quot;https://aviation.stackexchange.com/q/2566/193&quot;&gt;What is the measurement system used in the aviation industry?&lt;/a&gt; and related to &lt;a href=&quot;https://history.stackexchange.com/q/12089/2453&quot;&gt;this question from History&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can understand the arguments as to why adoption of SI units would not make sense for the general population, but aviation is a specialised business. All professionals are highly trained, and would (&lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;noreferrer&quot;&gt;should&lt;/a&gt;) be well versed in both systems anyways, so the transition would be much simpler from the point of view of human factors. The technology would probably be much harder to shift but again, with more and more displays and documentation going digital in cockpits, this again seems to be a &lt;em&gt;not so huge&lt;/em&gt; problem. Maintenance and manufacturing is again fairly specialised and restricted to a smaller number of companies as compared to the general case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the historical factors that lead up to the adoption of imperial units in the industry? Why are they still being used when widely accepted scientific standards exist?&lt;/p&gt;&#xA;" OwnerUserId="193" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2018-08-03T20:57:51.477" Title="Why doesn't the aviation industry use SI units?" Tags="&lt;commercial-aviation&gt;&lt;measurement&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2573" PostTypeId="2" ParentId="2570" CreationDate="2014-03-22T17:49:35.880" Score="2" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.topspeed.com/aviation/aviation-reviews/cessna/2010-2003-cessna-350-corvalis-ar83638.html&quot; rel=&quot;nofollow&quot;&gt;this page&lt;/a&gt;, the landing distance of the Cessna 350 is 2,350 feet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Nimitz-class_aircraft_carrier&quot; rel=&quot;nofollow&quot;&gt;Nimitz&lt;/a&gt; class carrier deck is close to 1,000 feet long, and can travel about 30 knots. If they were going full speed into a headwind, it &lt;strong&gt;might&lt;/strong&gt; be possible for them to stop in time, but it would be pretty scary, and if they ran off the end they would be run over by the carrier!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note however that the airplane would pretty much have to be directly above it when it happened, and I doubt that the military would like a civilian aircraft being that close in the first place so it's very unlikely to ever even be an option unless it was setup in advance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A different airplane like a &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Piper_PA-18&quot; rel=&quot;nofollow&quot;&gt;Super Cub&lt;/a&gt; or as you pointed out a &lt;a href=&quot;http://en.wikipedia.org/wiki/C-130_Hercules&quot; rel=&quot;nofollow&quot;&gt;C-130&lt;/a&gt;, which can land in about 300 feet could do it pretty easily, even without the wind as long as they don't get caught up in the arresting gear.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-22T21:35:12.210" LastActivityDate="2014-03-22T21:35:12.210" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2574" PostTypeId="1" AcceptedAnswerId="2580" CreationDate="2014-03-22T18:35:37.330" Score="16" ViewCount="33278" Body="&lt;p&gt;I've never worked for an airline, but I know that one of the benefits of working in the industry is that you can fly for free or almost free on a space-available basis.  I realize that every airline is slightly different, but what's the general procedure for this?  To provide a concrete example, let's say I live in New York and want to non-rev to Miami tomorrow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How would I know if a space is available?  How far ahead will I know that I have a seat?  Can more senior employees beat me out or is it first come, first served?  Do I need a boarding pass?  If not, how do I get past the TSA checkpoint?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In general, how does flying non-rev work?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="6886" LastEditDate="2015-11-12T17:56:11.470" LastActivityDate="2015-11-12T17:56:11.470" Title="What are the basics of flying non-revenue?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2575" PostTypeId="2" ParentId="2572" CreationDate="2014-03-22T18:36:21.053" Score="5" Body="&lt;p&gt;This is a historical development that dates back to that much of the early aviation equipment was sourced from the United States, and was consequently in imperial units. This in particular occurred after World War Two, and hence mixing them was a bad idea, and the imperial system stuck. Interestingly, the places where the US did not have a lot of influence- the former USSR and China for example- use metric.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for airspeed in Knots and distance in Nautical Miles, this comes from aviation's nautical heritage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All pilots can do the conversion, but it's rather that changing all the instruments from the imperial system to metric system that would cause a huge headache, among other things, and the cost would outweigh the benefits. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Instruments would have to be changed.&lt;/li&gt;&#xA;&lt;li&gt;All reference material would have to be converted.&lt;/li&gt;&#xA;&lt;li&gt;All maps/charts/etc. would have to be converted.&lt;/li&gt;&#xA;&lt;li&gt;Pilots would have to become accustomed to the new units and to learn the changed values which they will probably have memorised, such as important airspeeds.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-22T22:36:57.007" LastActivityDate="2014-03-22T22:36:57.007" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2578" PostTypeId="2" ParentId="2570" CreationDate="2014-03-22T18:51:18.830" Score="21" Body="&lt;p&gt;As Lnafziger says, a conventional landing is impossible for anything more than &lt;strike&gt;a tiny aircraft&lt;/strike&gt; STOL aircraft (Carrier 'runway' length: 200m). As you state however, if it was an emergency, the aircraft carrier has a &lt;strong&gt;special net which it can fold up to stop planes&lt;/strong&gt;, and since it can stop an F18 Hornet, it could probably take your Cessna as well :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/9e/US_Navy_DN-SC-93-04867_to_04876_S-3A_Viking_emergency_landing_USS_Abraham_Lincoln_%28CVN-72%29_animation.gif&quot; alt=&quot;net&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.927" LastActivityDate="2015-01-16T09:40:32.497" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="2579" PostTypeId="2" ParentId="2571" CreationDate="2014-03-22T19:34:23.473" Score="10" Body="&lt;p&gt;According to a friend of mine that has worked as an aircraft mechanic for the last 30 years or so, it depends on the manufacturer.  For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;American made aircraft, including Boeing, use SAE sized tools (US standard sizes)&lt;/li&gt;&#xA;&lt;li&gt;Airbus uses metric tools&lt;/li&gt;&#xA;&lt;li&gt;Hawker uses &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Standard_Whitworth#Comparison_of_standards&quot;&gt;British Standard Whitworth tools&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Dassault Falcon uses (believe it or not) a combination of SAE and metric.&lt;/li&gt;&#xA;&lt;li&gt;Bombardier uses SAE&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-25T18:11:32.327" LastActivityDate="2014-03-25T18:11:32.327" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2580" PostTypeId="2" ParentId="2574" CreationDate="2014-03-22T19:59:58.857" Score="20" Body="&lt;p&gt;There are a few classes of Non-rev travel.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jumpseating&lt;/li&gt;&#xA;&lt;li&gt;Online pass travel&lt;/li&gt;&#xA;&lt;li&gt;Interline pass travel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Jumpseating&lt;/h3&gt;&#xA;&lt;p&gt;This is open to pilots and flight attendants, air-traffic controllers (not sure if this is currently true, but it used to be), certain company and government officials (e.g. the FAA and others).&lt;/p&gt;&#xA;&lt;p&gt;In general pilots can only occupy pilot jumpseats and flight attendants can only occupy flight attendant jumpseats.  I know of cases where pilots can sit in the FA jumpseats but this is largely a topic of the Pilots and FA Union contracts.  In general pilots can jumpseat on any other 121 carrier and some 135 carriers.  Note that jumpseating does not necessarily mean you'll be in the cockpit, as current regulations stipulate you should not sit in the cockpit unless there are not seats in the cabin available.&lt;/p&gt;&#xA;&lt;p&gt;If you list for a jumpseat you will generally be the lowest priority for a cabin seat, boarding after all other non-rev travelers and then in a specified priority order jumpseaters will fill up the cabin and then the cockpit jumpseats until space is exhausted.&lt;/p&gt;&#xA;&lt;p&gt;Jumpseating is the most versatile of the options, but the most limited in who can use it.  It is good to keep in mind your jumpseat agreements probably allow jumpseating on cargo 121 carriers in addition to passenger 121 carriers, so keep Fedex, UPS, Atlas, etc in mind when travelling.  Your spouse/kids won't be able to join you though.&lt;/p&gt;&#xA;&lt;h3&gt;Online Pass Travel&lt;/h3&gt;&#xA;&lt;p&gt;The specifics of this travel depends on your airline, but I will speak in general terms.  Pass travel is usually available to the employee, the employeers domestic partner or spouse, the employees minor children and the employees parents.  There is usually also a program for a limited number of passes for friends (buddy passes).&lt;/p&gt;&#xA;&lt;p&gt;Pass travel is usually limited to your airline those you have a business relationship with.  For example a regional carrier can usually pass travel on the legacy carrier they contract with.  A legacy carrier can usually pass travel on its regional contracts.  If a regional contracts with multiple legacies, you sometimes only pass travel on the legacy system of the legacy you perform flights for.  It can be complicated.&lt;/p&gt;&#xA;&lt;p&gt;There is always a defined priority for pass travel.  In general employees ride before spouses/parents/children who ride before buddy passes (except when travelling together, you may all share the priority of the highest priority pass on the itinerary).  When multiple companies are involved, the priority levels may reflect a higher priority for the company operating the flight employees than the legacy/regional contract carriers.&lt;/p&gt;&#xA;&lt;p&gt;Again, this will vary greatly from company to company and you will learn the specific rules that apply to you when you are hired somewhere.&lt;/p&gt;&#xA;&lt;h3&gt;Interline travel&lt;/h3&gt;&#xA;&lt;p&gt;These passes are known as ID75, ID90, etc where the number is the percent discount from a &lt;em&gt;full fare&lt;/em&gt; ticket.  You can generally buy passes for yourself, your spouse/domestic partner and your children.  No buddy passes.&lt;/p&gt;&#xA;&lt;p&gt;To get an ID90, you visit your travel office and request an interline ticket for a specific city pair.  For example you can buy an ID90 for Rome - NYC.  You get an old school paper ticket for that route and no specific airline.  When you want to use the ID90, you present it to the ticketing agents for the airline you want to ride that flies the route you want to fly.  They will in turn issue you a non-revue standby boarding pass.  These are generally lower priority than online pass travel when it comes time to board.  These tickets are fully refundable, so they are often purchased as backups to get home when travelling in case you cannot get back with online passes.&lt;/p&gt;&#xA;&lt;h3&gt;How it all works&lt;/h3&gt;&#xA;&lt;p&gt;If you are the employee, you have a company ID and use this to get through security.  If you are the spouse/partner/child/buddy, then you will print out a standby boarding pass and use that to get through security.  You can check bags, which will get tagged standby and &lt;em&gt;should&lt;/em&gt; board if you do.  It can be good to remind the gate you have bags checked when you get a seat.&lt;/p&gt;&#xA;&lt;p&gt;If you are flying on your own carrier or under your legacy brand, you generally have computer access to the passenger boarding totals.  These can often be hard numbers of people booked, checked in and standbys listed.  You can use this to gauge the likelihood of getting on a plane.  If you are travelling offline then a carrier might have a phone number available but they may only tell you &amp;quot;it looks good!&amp;quot; or &amp;quot;it looks bad&amp;quot; and will not divulge numbers.&lt;/p&gt;&#xA;&lt;p&gt;Once you are at the gate, you play the waiting game.  You will have a boarding priority which may look something like this for a legacy carrier flight:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Legacy pilots&lt;/li&gt;&#xA;&lt;li&gt;Legacy flight attendants&lt;/li&gt;&#xA;&lt;li&gt;Legacy retired pilots/FA&lt;/li&gt;&#xA;&lt;li&gt;The legacies regional contract pilots / FA&lt;/li&gt;&#xA;&lt;li&gt;Legacy spouse/parents/domestic partner/kids&lt;/li&gt;&#xA;&lt;li&gt;The regional contract spouse/parents/domestic partner/kids&lt;/li&gt;&#xA;&lt;li&gt;Codeshare pass agreements&lt;/li&gt;&#xA;&lt;li&gt;Buddy passes&lt;/li&gt;&#xA;&lt;li&gt;Interline passes&lt;/li&gt;&#xA;&lt;li&gt;Cabin jumpseats&lt;/li&gt;&#xA;&lt;li&gt;Cockpit jumpseats&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;This will assuredly vary based on who you work for and who they contract with, and is just to illustrate the complexity of the priority structure.  Within each category listed above there is an internal priority that for many is based on date of hire, others based on time of listing.  Again, this varies.&lt;/p&gt;&#xA;&lt;p&gt;After all the confirmed revenue passengers board, the gate will board the revenue standby passengers, and once they are on and the number of empty seats is known (misconnects, people not in the boarding area 15 minutes prior to departure, etc), they will board according to the non-rev priority.  When the cabin is completely full, no more non-revs may board except for the jumpseaters, who may then fill the available jumpseats.&lt;/p&gt;&#xA;&lt;h3&gt;Putting it together&lt;/h3&gt;&#xA;&lt;p&gt;If you wanted to non-rev from NYC to Miami tomorrow and your company flies that route, then you just wake up in the morning, list yourself, take a look at the boarding totals and head to the airport.  If you don't even want to do that and you are a pilot, you just go down to the airport, find a gate with a plane headed to Miami and list for the jumpseat on that plane.  If the many rules of priority work out, you get on and you go to Miami.&lt;/p&gt;&#xA;&lt;h3&gt;Some considerations&lt;/h3&gt;&#xA;&lt;p&gt;Pass travel often has a dress code.  Don't show up in a tshirt and shorts unless you know you are allowed, you can be denied boarding.  Make sure all of your pass riders are behaving themselves.  This is especially important to impress on anyone you give a buddy pass, as when they screw up as a pass rider, &lt;em&gt;you&lt;/em&gt; can have your pass travel suspended as punishment.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-24T17:23:24.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2581" PostTypeId="1" AcceptedAnswerId="2611" CreationDate="2014-03-22T21:39:11.673" Score="12" ViewCount="1375" Body="&lt;p&gt;This might sound like a silly question to some, but is it possible to go and sit in the cockpit of a Boeing 737, somewhere in the UK? (Otherwise in Europe, or beyond).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe at a museum or something? I'm building a [currently tiny] home cockpit based on a 737, and I'd like to see how the real thing looks and feels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried searching online, but I couldn't find anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this isn't too dumb of a question, i.e. &quot;not possible Jim!&quot;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-22T21:47:56.370" LastActivityDate="2015-02-25T15:02:55.963" Title="Where can I go to sit in the cockpit of a Boeing?" Tags="&lt;passenger&gt;&lt;boeing&gt;&lt;boeing-737&gt;&lt;cockpit&gt;&lt;uk&gt;" AnswerCount="7" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2582" PostTypeId="2" ParentId="2566" CreationDate="2014-03-22T21:55:27.303" Score="24" Body="&lt;p&gt;Outside US, SI is generally used for &lt;strong&gt;everything except altitude, distance and speed&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Altitude: 1000 ft happens to be reasonable vertical separation, which is somewhat easier to calculate with than the corresponding metric figure 300 m.&lt;/li&gt;&#xA;&lt;li&gt;Distance: There are two quantities that were never converted to decimal. Time and &lt;em&gt;angle&lt;/em&gt;. Since we didn't switch to gradians, it makes sense to keep nautical mile, which corresponds to 1 minute along meridian or equator, as it makes calculating distances from navigational maps somewhat easier. If the maps were marked in gradian coordinates, 1 gradian would be 100 km and kilometres would be used.&lt;/li&gt;&#xA;&lt;li&gt;Speed: Obviously based on the unit of distance in use.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In Russia, Commonwealth of Independent States (most former Soviet countries) and China (and I am not sure whether some other Asian countries), metric system is used for everything. I believe in Russia they recently switched to flight levels based on feet, but they do use metres below transition altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before second world war, aircraft built in continental Europe usually had instruments in metric units as well. However before the war aviation was more advanced in the USA, instrument procedures were developed in USA and after the war there was surplus of US-built planes, so most of the world just adopted the US procedures including the units they used as everybody using the same units was more important than any personal preferences. Without these reasons we'd be probably using metric in Europe for everything too.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-02-10T08:58:29.613" LastActivityDate="2015-02-10T08:58:29.613" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2583" PostTypeId="2" ParentId="2572" CreationDate="2014-03-22T22:20:42.413" Score="23" Body="&lt;p&gt;Non-SI is &lt;strong&gt;only used for altitude, distance and speed&lt;/strong&gt; except in US and some other American countries.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Altitude is in feet because 1000 ft happens to be reasonable vertical separation and 1000 ft is easier to calculate with than the corresponding SI figure 300 m. Also the procedures for instrument flying were first developed in the USA using feet.&lt;/li&gt;&#xA;&lt;li&gt;Distance is in nautical miles because it is related to the unit used for measuring latitude and longitude. 1 nautical mile corresponds to 1 minute latitude (and longitude on the equator), which makes it easier to calculate distances from navigational maps using the grid lines as scale (large area navigation maps need to preserve angles, so they can't have constant scale). If angles were converted to decimal, 1 km would be 1/100 gradian. Alas, angles and time were never converted to decimal.&lt;/li&gt;&#xA;&lt;li&gt;Speed obviously based on the distance unit in use.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Nevertheless if it was not for the prevalence of US-built planes after WWII and more advanced state of aviation in the USA at that time, we would probably be using metric in Europe too as continental planes before WWII usually had instruments in metric.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-03T07:04:59.487" LastActivityDate="2015-06-03T07:04:59.487" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2584" PostTypeId="2" ParentId="2566" CreationDate="2014-03-22T22:43:51.613" Score="6" Body="&lt;p&gt;Unless Boeing has recently changed to the metric system in their design work, the short answer to the question as to whether Boeing and Airbus use different systems insofar as aircraft manufacture is yes. I'm only familiar with Boeing up through the 747-400. Perhaps others can provide an answer for later models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing Weight and Balance Control and Loading manuals I have do provide kilogram pages following the pound pages, but that the pound is the controlling unit is also stated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, for moment limitations, the manuals follow the inch-pound pages with inch-kilogram pages. In other words, they're mixing systems, which I believe to be unwise as the net effect is to introduce a third, hybridized system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the past, many 747 freighter flights that I flew were slightly over gross at takeoff due to the fact that the common conversion used for kilograms to pounds was 2.2 when the actual value is 2.20462262.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I remember, only the U.S. and Liberia are still non-metric officially. There is a political dimension to this which you can explore at &lt;a href=&quot;http://en.wikipedia.org/wiki/Metrication_in_the_United_States&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Metrication_in_the_United_States&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="753" LastEditDate="2014-07-11T13:19:46.387" LastActivityDate="2014-07-11T13:19:46.387" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2585" PostTypeId="2" ParentId="2581" CreationDate="2014-03-22T23:11:06.387" Score="9" Body="&lt;p&gt;There is a company called &lt;a href=&quot;http://www.flightexperience.com/&quot;&gt;Flight Experience&lt;/a&gt; which builds 737 simulators and offers their use to the public. These are fully certified simulators and are frequently used by commercial pilots for currency training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their closest location to London appears to be in Paris.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had an opportunity to fly one of their simulators a few years ago, and it was a lot of fun. We spent some time doing landings at the old Kai Tak airport in Hong Kong.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-22T23:11:06.387" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2586" PostTypeId="2" ParentId="2574" CreationDate="2014-03-23T00:03:34.827" Score="12" Body="&lt;p&gt;The exact procedures, policies and systems are going to vary depending on the airline, but the following is based on my non-rev experiences with a particular airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Booking your flight and checking loads&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First up, most airlines will have some sort of system whereby you can log in and view flights and availability. This system will work similar to booking a flight through the normal system, but will also give an indication of availability. For the system I am familiar with, it shows a breakdown of the number of seats available for sale in each cabin, and the number of seats booked in that cabin (note that this does not reflect the number of actual seats, as airlines often overbook). It also lists any other staff members who are listed for standby on the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the list of staff on standby, these are organised by priority. Priority is based on role at the airline, number of years served, and type of standby ticket .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on all the above, you can get a rough overview of the loads for the slight, and how likely you are to get on-board. However, there are a few things to bear in mind. Firstly, a lot of people tend to book last minute, particularly on key business routes. Also, if you are flying from an airlines hub, there may well be a number of passengers that miss a flight, and get transferred onto the flight you are looking at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short - you never know until you get to the airport, even then it's a waiting game.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;At The Airport&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once at the airport, you check in as normal. Depending on the loads of the flight, they may issue you a seat and confirm you on the flight (if it's completely empty), but more often than not, you remain on standby. The procedure here varies depending on whether you are at your airlines hub, or down route. Typically at the hub, there is a dedicated staff travel waiting room, where you can go and wait for information on your flight. At a non-hub airport, you are normally checked in and your bags tagged as &quot;standby&quot;, then you are issued a boarding pass (with no assigned seat) to get you through security. You then wait at the gate for information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Waiting Game&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless the flight is completely empty, you often wont know if you are on the flight until check-in closes (approx 30-40 minutes before departure). At this point the flight is no longer open for transfer passengers, and they know how many passengers booked on the flight have turned up. At this point you will either be called to go to a check-in desk, or given a boarding pass at the gate. Although once check-in closes, there is varying amounts of paperwork to complete, so if you are waiting at the gate it might take another few minutes before everything else is sorted and they assign you a seat.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastActivityDate="2014-03-23T00:03:34.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2587" PostTypeId="2" ParentId="2554" CreationDate="2014-03-23T01:57:59.843" Score="19" Body="&lt;h3&gt;What is turbulence?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Turbulence is&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;random and stochastic&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each realization of a turbulent flow is unique and fluctuations in velocity are very irregular in space and time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;dissipative&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence cannot maintain itself and will decay into laminar flow without energy input from the environment (e.g. mean shear in the velocity field or buoyancy). Reducing viscosity in a flow does not remove dissipation, it just moves dissipation to ever decreasing scales.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;diffusive&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A time-averaged scalar transported in a turbulent flow will have larger plume than that of a laminar flow.  For example, if you injected a dye into a smooth flowing river and one into a turbulent flowing river, the dye plume would cover a larger area in the turbulent flow.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;three dimensional&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3D vortex dynamics play a very important role in turbulence and for most cases you cannot represent a turbulent flow as a 2D problem.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;occuring on a wide range of scales&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is perhaps the most important distinction.  When I say scale, I am referring to a characteristic length and velocity of an eddy, or swirl.  Turbulence is produced at larger scales and the transfers its energy to smaller and smaller scales.  At some (very small) scale, dissipation starts happening and the turbulence decays.  A feature of a turbulent flow is energy at all scales, which basically means there are whirls of all sizes and it is the interaction between all of these swirls that gives turbulence.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;How does it happen?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The main production of turbulence is through mechanical production and buoyant production.  Turbulence happens because energy is being put into it via these production methods.  Turbulence will decay on its own but will not stop until production ceases.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Mechanical production can be envisioned as a shear flow, or air of two different speeds interfacing.  This can also be wind against a wall, or around some object.  The velocity gradient at the periphery of the jetstream is a shear flow, and the boundary layer that we live in is a sheared environment on most days.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Buoyant production is through buoyancy.  Relatively warm parcels rise and this is balanced by subsidence and if you follow these thermals and the descent between them and squint hard enough, you can envision eddies on the largest scales. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both of these methods put energy into turbulence at large scales.  For boundary layer flows, this can be on the order of a kilometer or more, typically the height of the boundary layer.  These big eddies will have perturbations of their own and these smaller perturbations are the next smaller scale.  Energy is cascaded downward until the sizes of the eddies are small enough that viscosity dominates over inertial forces and the energy is then lost from the turbulence as heating.  The superpositioning of these eddies at all scales resembles a jumbled bumpy mess, and this is precisely how we experience turbulence.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-23T13:08:23.917" LastActivityDate="2014-03-23T13:08:23.917" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2588" PostTypeId="2" ParentId="2561" CreationDate="2014-03-23T02:29:05.673" Score="1" Body="&lt;p&gt;To add to voretaq7's answer: In addition to the desire to gain as much altitude as quickly possible, there is the following consideration: most engine failures happen when the power configuration is changed (a lot of oil is moving through the hub to adjust the rpm, for example), so changing the power should be delayed until you have gained enough altitude for a safe emergency landing (in real life this might not be possible, of course). Thus your second scenario is preferable under normal circumstances.&lt;/p&gt;&#xA;" OwnerUserId="1343" LastActivityDate="2014-03-23T02:29:05.673" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2589" PostTypeId="1" AcceptedAnswerId="2592" CreationDate="2014-03-23T02:56:43.420" Score="28" ViewCount="20138" Body="&lt;p&gt;How do airliners cross the ocean without GPS?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they use dead-reckoning or are there navigation aids floating out there?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-03-23T08:25:22.653" LastActivityDate="2019-02-18T12:42:41.283" Title="How do airliners cross the ocean without GPS?" Tags="&lt;navigation&gt;&lt;gnss&gt;&lt;oceanic&gt;&lt;navaids&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2590" PostTypeId="2" ParentId="2472" CreationDate="2014-03-23T03:42:59.960" Score="4" Body="&lt;p&gt;I provided a potential mathematical solution on deriving the flight paths using the ACARS data on 17 March (before the possible flight paths were published by the authorities) on CNN's iReport: &lt;a href=&quot;http://ireport.cnn.com/docs/DOC-1108312&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://ireport.cnn.com/docs/DOC-1108312&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The key to finding MH370 without the aid of the transponder data but with regular attempted ‘handshakes’ from the ACARS satellite is by a process known as “vector addition”. If the last handshake with the ACARS satellite took place at 8.11am as reported then depending on the frequency of the previously attempted handshakes (half hourly or hourly, there seems to be some discrepancy in the reported frequency) a set of flight route models can be easily constructed giving a high probably of the final location based on the accurate last known location at 2.40am. Therefore, depending on the frequency of the ACARS handshakes there should be at least 6 and up to 12 vectors that could be mathematically solved.&lt;/p&gt;&#xA;&lt;p&gt;Assuming a constant speed for the first probability model, each time the ACARS handshake occurs it gives only a footprint angle on the Earth (as has been shown on the reported 8.11am ACARS ping map; 40 degrees). The next time it handshakes another angle is indicated. At a constant speed only two possible headings are possible to ‘join’ the ACARS isogons (for the plane to get from one ‘angle’ to another). If MH370 was heading in generally the same direction or arcing across the sky, (even if there was some tacking back and forth like a yacht) only one of the possible vector solutions will be valid.&lt;/p&gt;&#xA;&lt;p&gt;If the vectors from the last known location at 2.40am were systematically added together the final solution at 8.11am will bisect one of the two arcs provided by the authorities. Subsequent models at different average speeds and taking into account routes that would more effectively avoid radar detection would refine the models to a few high probability scenarios and narrow down the search area considerably.&lt;/p&gt;&#xA;&lt;p&gt;It’s simple mathematics but there is no indication the authorities are using it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As RedGrittyBrick has pointed out this is almost definitely how the flight path was estimated. The reason for the two flight paths is probably illustrating the two end member solutions based on the accumulated error using this technique (the more times you add one vector to another the more error can be introduced). Hence the two predicted flight paths diverge.&lt;/p&gt;&#xA;&lt;p&gt;The reason for the confidence by the authorities in the southern Indian Ocean route is that the mirror set of solutions would need MH370 to pass straight over India and Pakistan; and they have emphatically denied this could have taken place.&lt;/p&gt;&#xA;&lt;p&gt;Therefore there is the highest probability that MH370 ended up in the region of the southern Indian Ocean they are currently searching.&lt;/p&gt;&#xA;&lt;p&gt;I am somewhat saddened that these probability models were not derived within days MH370 went missing and that at least 7 days were wasted searching in other areas.&lt;/p&gt;&#xA;" OwnerUserId="1722" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-24T21:38:31.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2592" PostTypeId="2" ParentId="2589" CreationDate="2014-03-23T04:22:36.860" Score="26" Body="&lt;p&gt;Well, most airlines &lt;em&gt;do&lt;/em&gt; cross the ocean with GPS in today's world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, most (if not all) transcontinental airliners, and many flying domestic routes as well, have what's called an &lt;a href=&quot;https://aviation.stackexchange.com/questions/2275/what-is-an-inertial-navigation-system-how-does-it-work&quot;&gt;inertial navigation system&lt;/a&gt; (a form of dead-reckoning where gyros and accelerometers are used to compute changes in position). The INS feeds into the flight management computer which is used to cross-check the GPS position, and can be used as a primary navigation source should the GPS signal be lost or corrupted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prior to GPS, inertial navigation was the primary means of navigating across oceans. However, a great many airplanes did cross oceans before INS... with varying success. The general idea was to use a combination of dead-reckoning, radio beacons where you can find them (small islands and coastlines), the sun (with the help of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Sextant&quot; rel=&quot;noreferrer&quot;&gt;sextant&lt;/a&gt;) during the day, and the stars at night. Hopefully, this puts you in position after some period of time to pickup ground-based navigational aids, or to identify a coastline. This actually works pretty well if your wind estimates are good, and the margin for error is high enough. As DeltaLima points out, long-range radio navigation systems also started to emerge around World War II (LORAN and Decca) which had a much greater range than previous radio beacons, and therefore decreased the amount of time required to fly by dead-reckoning alone. By the time inertial navigation became prevalent in the 1970's, airlines were already providing reliable transcontinental passenger flights every day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possible outcome is that your plane is lost in the ocean, never found, and the Discovery Channel funds an expedition to look for you 75 years later.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-03-23T16:42:27.523" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2593" PostTypeId="2" ParentId="2570" CreationDate="2014-03-23T07:19:19.213" Score="7" Body="&lt;p&gt;The published landing distance for the Cessna is the certified distance - that's what it needs in a worst-case, no-flaps, high, hot, zero-wind landing. Any pilot will tell you that they rarely need the whole runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the big picture of the aircraft carrier. The ocean is HUGE (ask the people searching for Malaysia 370) and rather featureless. Private planes rarely cross large paths of open ocean as it's often the longest route to where they are going rather than the shortest. So the chances of a carrier battle group being anywhere near you are extremely small. If your plane is flying well enough to find the CBG, come in behind and line up for a landing then you probably don't need it in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, light aircraft would have no technical problems landing on the deck. Lots of room with a 30-50kt headwind, no need for a tailhook or nets as you don't weigh 30,000 pounds or come in at 200kt IAS on full afterburner. The chances of a non-navy-trained pilot hitting the touchdown zone of a runway moving away from them at 30kt and pitching up and down several meters is laughably small. You would either miss and have to go around (again, if you can do that, you don't need the carrier in the first place) or make a mess on the fantail. Even navy pilots do this on occasion, but they have ejection seats.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-10-16T07:57:06.657" LastActivityDate="2014-10-16T07:57:06.657" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2594" PostTypeId="2" ParentId="2589" CreationDate="2014-03-23T07:32:08.110" Score="20" Body="&lt;p&gt;We were crossing the seas centuries before GPS, INS or really any other form of modern technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All you need is a clock, a compass and a sextant. And some largely-forgotten skills, like how to do math without a smartphone. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-03-23T07:32:08.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2595" PostTypeId="2" ParentId="2589" CreationDate="2014-03-23T09:05:38.607" Score="7" Body="&lt;p&gt;Most aircraft cross the atlantic by GPS, usually with INS as backup. INS as the primary form of navigation is still used as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, a combination of dead reckoning and long range radio navigation systems were used on transatlantic routes. These include &lt;a href=&quot;http://en.wikipedia.org/wiki/Decca_Navigator_System&quot; rel=&quot;nofollow&quot;&gt;Decca&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/LORAN&quot; rel=&quot;nofollow&quot;&gt;LORAN C&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/OMEGA_Navigation_System&quot; rel=&quot;nofollow&quot;&gt;Omega&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Omega was shut down in 1997, Decca in 2000 and LORAN C ceased in 2010.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="6" LastEditDate="2014-03-23T16:35:52.093" LastActivityDate="2014-03-23T16:35:52.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2596" PostTypeId="2" ParentId="2570" CreationDate="2014-03-23T09:32:59.547" Score="29" Body="&lt;p&gt;A South Vietnamese Air Force Cessna O-1 landed on the USS &lt;em&gt;Midway&lt;/em&gt; at the end of the Vietnam War. Fixed-wing VNAF aircraft usually flew to Thailand, and the naval evacuation was carried out by helicopter (with crews sometimes ditching in the water after the flight decks ran out of room), but this O-1 pilot wound up making his first carrier landing, with his family on board and an hour of fuel left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Operation_Frequent_Wind#Chaos_at_sea&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia wrote a paragraph about it and has another couple photos.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1HDGb.jpg&quot; alt=&quot;Major Buang lands his Cessna O-1 on USS Midway&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1080" LastEditorUserId="1080" LastEditDate="2014-03-23T10:32:19.297" LastActivityDate="2014-03-23T10:32:19.297" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2598" PostTypeId="1" CreationDate="2014-03-23T11:36:07.087" Score="1" ViewCount="113" Body="&lt;p&gt;I had posted the question below on &lt;a href=&quot;http://www.nytimes.com/2014/03/21/technology/though-high-tech-tools-exist-satellites-dont-track-planes.html?comments#permid=11387412%27&quot; rel=&quot;nofollow&quot;&gt;a New York Times article&lt;/a&gt;, but did not get any useful replies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The series of six successful Inmarsat pings known to exist, MAY carry enough information to say if the plane most likely went along the S or the N arc we see in reports. Unfortunately, only the last ping (at 8:11AM) is available publicly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the basic idea on extracting the information: A Malaysian military satellite gave the last geographic fix of ML370 at 2:15AM. A circle can be drawn with this point as the center and distance traveled at maximum speed as diameter, confining the plane's position at 3:11AM. From the ping at 3:11AM, another circle can be drawn, like the one drawn at 8:11AM. The intersection of the two circles give an arc of most likely 3:11 AM positions.&#xA;At 4:11AM, we will have a series of circles from max distance and one circle from the ping. These intersections will give a series of possible arcs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This process can be repeated (with increasing complexity, of course) giving us a series of most likely positions at 3:11AM, 4:11AM, 5:11AM, etc. If the &lt;em&gt;trajectory&lt;/em&gt; of these sequence of spaces has a N/S directionality, we can say with some confidence that the aircraft went that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, this would be more complicated. For example, the plane most probably did not go along a straight path at max speed. However, useful inferences can be made by adding other information available. For example, from the ping circles separated by one hour, we can get plausible directions the plane may have taken. Why isn't anyone pursuing this line of analysis? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a bit more detail &lt;a href=&quot;https://sites.google.com/site/debprakash/mh370&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. Anyone estimating possible paths of MH370 quantitatively?&lt;/p&gt;&#xA;" OwnerUserId="1724" LastEditorUserId="22550" LastEditDate="2018-11-22T14:25:47.683" LastActivityDate="2018-11-22T14:25:47.683" Title="Anyone estimating possible paths of MH370 quantitatively?" Tags="&lt;navigation&gt;&lt;radio-communications&gt;&lt;mh370-incident&gt;" AnswerCount="0" CommentCount="3" FavoriteCount="1" ClosedDate="2014-03-23T16:52:57.853" ContentLicense="CC BY-SA 3.0" />
  <row Id="2599" PostTypeId="2" ParentId="2589" CreationDate="2014-03-23T13:45:08.333" Score="1" Body="&lt;p&gt;They do use GPS, with backups, as the other answers describe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your question is inspired by MH370, remember that GPS tells you where you are: it doesn't tell anyone else where you are. GPS works by having a bunch of satellites sending out signals and, based on the signals you hear, you can calculate your own position. A GPS user doesn't transmit anything back to the satellites. What MH370 lacked was a system that was reporting its location back to base.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-03-23T13:45:08.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2600" PostTypeId="5" CreationDate="2014-03-23T14:03:08.410" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-23T14:03:08.410" LastActivityDate="2014-03-23T14:03:08.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2601" PostTypeId="4" CreationDate="2014-03-23T14:03:08.410" Score="0" Body="For questions relating to Standards and Recommended Practices stipulated by ICAO to address safety risks." OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-03-23T14:50:58.813" LastActivityDate="2014-03-23T14:50:58.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2602" PostTypeId="1" CreationDate="2014-03-23T14:56:15.943" Score="6" ViewCount="9931" Body="&lt;p&gt;Ok, so this may be more of an english lanugage question, and I can confirm from context that when the fuel shutoff valve is ON fuel does indeed flow to the engine, but wouldn't that just make more sense to call that valve the fuel valve?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the component that shuts fuel off is on, operational, in use, functioning, etc., shouln't fuel be shut off, as the name implies?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize this could be seen as a quibble, but confusion causes accidents and IMO this is wildly confusing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the Cessna 152 checklist today I noticed this interesting quirk. On the regular checklist side (pre-takeoff, maneuver, etc.) the checklist reads &quot;Fuel Shuttof Valve - ON&quot;, but on the &lt;strong&gt;emergency&lt;/strong&gt; checklist for an engine fire it merely states &quot;Fuel Valve - OFF&quot;.  &lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="267" LastEditDate="2014-03-23T19:40:54.553" LastActivityDate="2019-02-27T12:19:54.190" Title="If the &quot;Fuel Shutoff Valve&quot; is ON, wouldn't fuel be cut off?" Tags="&lt;safety&gt;&lt;terminology&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2603" PostTypeId="2" ParentId="2602" CreationDate="2014-03-23T15:39:26.003" Score="7" Body="&lt;p&gt;I can see where that can be confusing, but it comes down to perspective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a maintenance and engineering perspective, you are actuating the fuel &lt;em&gt;shutoff valve&lt;/em&gt; which controls the fuel to the engine.  The actual terminology when referring specifically to the valve would be opened or closed, which would result in the fuel being on or off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a pilot perspective you are simply turning the &lt;em&gt;fuel selector&lt;/em&gt; on and off, which happens to be connected to the fuel shutoff valve.  The pilot doesn't even need to know about the valve, so they placard it from the operational perspective in the cockpit and say whether the &lt;em&gt;fuel&lt;/em&gt; is on or off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.stevewilsonblog.com/wp-content/uploads/2012/08/Highwing-and-lowwing-Fuel-Valves.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hYlnF.jpg&quot; alt=&quot;fuel selector&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that these are placarded as a &lt;em&gt;fuel selector&lt;/em&gt; and &lt;em&gt;fuel off&lt;/em&gt; both of which seem pretty clear to me.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-23T15:51:24.543" LastActivityDate="2014-03-23T15:51:24.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2604" PostTypeId="2" ParentId="2602" CreationDate="2014-03-23T15:39:40.857" Score="4" Body="&lt;p&gt;I'd think that 'fuel shutoff valve' is a good name, but I'd think it's more sensible to use alternative terms to on/off. I think however most pilots will very early learn this and that it can't really be a problem. They know which position it should be in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few aircraft I can think off will avoid this by only using a using a more expressive term than on or off. For instance: OPEN-ON or likewise CLOSED-OFF or even more simply, OPEN or CLOSED. Some also explicitly state the difference, for instance 'PULL-OFF', like the aircraft below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZRbqk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZRbqk.jpg&quot; alt=&quot;valve&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://missions.capnhq.gov/ops/dot/school/GA8cfm/images/fuelgauge2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;capnhq.gov&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-24T13:51:14.343" LastActivityDate="2019-02-24T13:51:14.343" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2605" PostTypeId="1" AcceptedAnswerId="2606" CreationDate="2014-03-23T17:26:01.320" Score="32" ViewCount="4500" Body="&lt;p&gt;I'm wondering if large A3x0/B7x7 airliners could be operated without ground support. Short of using the inflatable slides, I guess at least stairs would be required to load/unload passengers. Apart from that, assuming fuel and push-back is not required, would it be possible to land, switch the engines and systems off and then take-off again without electrical, A/C, etc. ground support?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If possible, are there any circumstances where this is routinely/occasionally done? I know that it's definitely the case for smaller aircraft such as an ATR 72 servicing remote airports - I experienced that at e.g. Luang Prabang airport.&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="30934" LastEditDate="2018-08-16T13:33:45.313" LastActivityDate="2019-02-28T20:14:27.683" Title="Can large airliners be operated without ground support?" Tags="&lt;airliner&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2606" PostTypeId="2" ParentId="2605" CreationDate="2014-03-23T17:28:49.303" Score="19" Body="&lt;p&gt;In a word, yes.  The APU (auxiliary power unit) will supply air pressure and power the electrical systems needed to start the aircraft.  No ground support is required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flyingmag.com/pilots-places/pilots-adventures-more/jumpseat-its-all-about-apu&quot; rel=&quot;noreferrer&quot;&gt;http://www.flyingmag.com/pilots-places/pilots-adventures-more/jumpseat-its-all-about-apu&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's routinely done all the time!  Next time you're at the airport, watch a 7xx or A3xx.  Ignoring stairs, fuel, food, toilet drains etc there is sometimes no external air or power supply attached.  The APU will be running during boarding to power the aircraft and condition the cabin.  It is then used to start engines during the pushback.  When in the cabin, you will notice the packs being switched off (the packs supply cabin air) as the air is diverted to the engine starters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only times I've seen this not done is when an external air conditioning cart is attached as the APU cannot cool the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-02-08T11:34:07.313" LastActivityDate="2016-02-08T11:34:07.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2607" PostTypeId="2" ParentId="2605" CreationDate="2014-03-23T20:13:32.183" Score="46" Body="&lt;p&gt;There's a good example which is the A319 LR which flies scientists down to Antartica. They utilize (very) little ground support, except for the stairs (they seem to have inbuilt ones in the front as well, although these are not used on site) and the trucks to offload the cargo. APU provides the power on the ground, and the aircraft has sufficient juice in the tanks to make the round trip without refuelling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RDeWP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RDeWP.jpg&quot; alt=&quot;onsite&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://images.smh.com.au/2012/10/23/3737217/art-RUNWAY-620x349.jpg&quot; rel=&quot;noreferrer&quot;&gt;smh.com.au&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read up on it &lt;a href=&quot;http://www.antarctica.gov.au/living-and-working/travel-and-logistics/aviation/intercontinental-operations/a319-background-information&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. She does weekly flights from Hobart to Wilkins aerodrome in Summer. 4 hours and 30 minutes of flying right into the uninhabited :)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-02-28T20:14:27.683" LastActivityDate="2019-02-28T20:14:27.683" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="2608" PostTypeId="1" CreationDate="2014-03-23T21:58:36.160" Score="11" ViewCount="4925" Body="&lt;p&gt;I'm wondering by &lt;strong&gt;which method this sort of aircraft panel that enabling backlighting are made?&lt;/strong&gt; What is the process? I've gathered they are acrylic but how is the gray paint selectively removed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.simparts.de/WebRoot/Store/Shops/15465782/4B72/6E37/0BF8/50E9/641B/C0A8/28BA/29AA/A320-OHP-009-5.jpg&quot; rel=&quot;noreferrer&quot;&gt;pic http://www.simparts.de/WebRoot/Store/Shops/15465782/4B72/6E37/0BF8/50E9/641B/C0A8/28BA/29AA/A320-OHP-009-5.jpg&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-02-07T21:25:29.040" Title="How are backlit aircraft panels (for simulators) made?" Tags="&lt;flight-simulator&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2609" PostTypeId="2" ParentId="2589" CreationDate="2014-03-23T22:01:07.927" Score="15" Body="&lt;p&gt;In the days before GPS, we routinely crossed the oceans using inertial navigation systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system I was familiar with used 3 separate inertial systems (Carousel was the brand name). You could choose to navigate by any single one, but the most common way of using them was to have the autopilot &quot;average&quot; the positions. You could also choose to exclude any given INS, in which case if you were averaging, you were averaging only two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the North Atlantic MNPS airspace system, You manually updated each INS passing over your last known ground position fix. When you passed over your first ground-based nav fix on the other side, you again manually updated the INSes with that information and then recorded in the maintenance log how far off left or right each INS was in the maintenance log. There were standards. Offhand I'm not sure I am remembering them correctly, but what I seem to recall was a max error of 2 nautical miles per hour flown without update. The MNPS had at the time a max error allowed without penalty of 10 nautical miles left or right of course. If that was exceeded, points were deducted from your company's score. Lose enough points and the company would not be allowed in fly in MNPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Off course errors of two to six nautical miles for a crossing were typical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is the story, true or not I do not know, of the captain who, when hand held GPSs first became available, used one to cross the North Atlantic, and had a near zero off course error. When ATC complimented him on that, he blurted out that he had used his hand-held. He was subsequently violated for using a non-approved navigational system. Whether the incident really happened, I don't know, but an airline's FAA approved op specs specifies not only which navigation methods are to be used but also which systems by brand and model name (at least back when I was flying).&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-03-23T22:01:07.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2610" PostTypeId="2" ParentId="2608" CreationDate="2014-03-23T22:26:18.930" Score="3" Body="&lt;p&gt;This &lt;a href=&quot;http://www.youtube.com/watch?v=DKhq8vWqcR4&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt; says the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Here's my Tonson TS-3040C CNC making an EFIS panel for my flight&#xA;  simulator. For the lettering I am using a 0.4mm End Mill and for&#xA;  cutting out I'm using a 1mm End Mill. RPM is 10000 and movement is&#xA;  300mm / Min. &lt;strong&gt;The material is Cast Acrylic which I have given one coat&#xA;  of black paint and two coats of grey paint.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So that's at least one method, but there are probably more...&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-23T22:36:43.637" LastActivityDate="2014-03-23T22:36:43.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2611" PostTypeId="2" ParentId="2581" CreationDate="2014-03-23T23:08:32.660" Score="5" Body="&lt;p&gt;Cotswold Airport, near the village of Kemble in Gloucestershire, England.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cotswolds landing strip, has become the busiest aviation scrapyard in the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HVY6R.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lA1hI.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually the cockpit parts are taken out before they end up there, but you never know; you may get lucky and they grant you access for a day. I don't see why not! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chevron Aircraft Maintenance Ltd is responsible for the dismantling of all Boeing 737 series aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1732" LastEditorUserId="97" LastEditDate="2014-03-24T11:01:43.257" LastActivityDate="2014-03-24T11:01:43.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2612" PostTypeId="2" ParentId="2532" CreationDate="2014-03-23T23:52:08.587" Score="1" Body="&lt;p&gt;It may possible like the US Airways Flight 1549 ditched in the Hudson River&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YFLFr.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was in a river with smooth water. I'm not sure if there's ever been a passenger jet successfully land intact on the sea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the Malaysian flight successfully ditched like Flight 1549, then I'm not sure if the plane could float for hours. It would sink for sure if the doors were opened.&lt;/p&gt;&#xA;" OwnerUserId="1732" LastEditorUserId="97" LastEditDate="2014-03-24T11:11:23.767" LastActivityDate="2014-03-24T11:11:23.767" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2613" PostTypeId="2" ParentId="2608" CreationDate="2014-03-24T02:15:56.447" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.mikesflightdeck.com/pedestal/panels__lighting.html&quot; rel=&quot;nofollow&quot;&gt;This page&lt;/a&gt; has some good information and a graphic, looks like the same as shown in the video Manfred posted. Clear plastic with an opaque layer that is engraved off, and lighted from beneath.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-24T02:15:56.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2614" PostTypeId="2" ParentId="2602" CreationDate="2014-03-24T02:34:49.397" Score="-1" Body="&lt;p&gt;Shutoff has a negative connotation, but the word ON is (highly) associated with the engine running. So if SHUTOFF is ON, is the shutoff valve operational (cutting the fuel off) or do we run with our standard interpretation of the word ON - that something essential (fuel supply) is functioning? I can see a pilot in an emergency, when her or his brain is on the edge of panic, forgetting their training and operating the valve incorrectly. I'd suggest it would be clearer to keep the word Shutoff, but make it one of the options, rather than the name of the whole control.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3pXNt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3pXNt.png&quot; alt=&quot;alternative fuel switch&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www-ist.massey.ac.nz/plyons/AircraftFuelSwitch.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;massey.ac.nz&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1737" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-02-27T12:19:54.190" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="2615" PostTypeId="2" ParentId="2565" CreationDate="2014-03-24T02:47:42.160" Score="3" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.casa.gov.au/wcmswr/_assets/main/manuals/regulate/aocm/220r015_Vol2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CASA AOC Handbook&lt;/a&gt;, section 15.3.1.2, pilots do need to have specific training. Most of this training is regarding engine failures and emergency landings, in some situations in IMC.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;CASA requires that all ASETPA operators have a training and checking&#xA;organisation.&lt;/p&gt;&#xA;&lt;p&gt;The CASA Inspector will verify that for ASETPA&#xA;operator’s the following additional procedures are included within the&#xA;training and checking organisation:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine failure or malfunction which necessitates stopping the aircraft on the ground&lt;/li&gt;&#xA;&lt;li&gt;Engine failure or malfunction which necessitates an off-airport landing after take- off on the most suitable terrain in the vicinity of the aerodrome. These can be organised into a number of procedures, depending on the height of the aircraft at the time of the failure&lt;/li&gt;&#xA;&lt;li&gt;Engine failure or malfunction which necessitates turning to execute a glide landing upon a serviceable runway, including a ‘turn-back’ manoeuvre. This procedure is to contain a minimum indicated airspeeds and altitudes&lt;/li&gt;&#xA;&lt;li&gt;Engine malfunction, during climb, cruise and descent and from the approach to land phase in VMC and IMC&lt;/li&gt;&#xA;&lt;li&gt;Additional procedures for the conduct of a forced landing in IMC to ground level&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The next section discusses route limitations, which I am assuming the pilots should at least be familiar with.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-24T02:47:42.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2617" PostTypeId="2" ParentId="1436" CreationDate="2014-03-24T09:27:39.797" Score="8" Body="&lt;p&gt;When looking at the front of the plane, I usually look for the &lt;strong&gt;clipped outer-upper cockpit window corners&lt;/strong&gt;. The Boeings have a 90-degree corner, the Airbusses are typically 'clipped' at the corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737 cockpit:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/0MFkg.jpg&quot; alt=&quot;Boeing 737 cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320 cockpit:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/SpbIx.jpg&quot; alt=&quot;Airbus A320 cockpit&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="354" LastActivityDate="2014-03-24T09:27:39.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2619" PostTypeId="1" AcceptedAnswerId="2741" CreationDate="2014-03-24T11:42:55.603" Score="7" ViewCount="1212" Body="&lt;p&gt;This recent &lt;a href=&quot;https://aviation.stackexchange.com/questions/2589/how-do-airliners-cross-the-ocean-without-gps#comment4991_2592&quot;&gt;comment&lt;/a&gt; reports that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the IMU on new (plane) would localize the aircraft to within 3 feet&#xA;  after a cross-country flight, without any GPS input other than the&#xA;  starting location.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I somewhat doubt about this statement, at least for an IMU based solely on inertial measurement: over the duration of a flight, I fear much more error accumulates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So &lt;strong&gt;what's the precision of a modern Inertial Measurement Unit&lt;/strong&gt; over say the duration of a flight, and &lt;strong&gt;from what sources is that obtained&lt;/strong&gt;? If some source (in particular, GPS) becomes unavailable, how does it degrade that accuracy?&lt;/p&gt;&#xA;" OwnerUserId="1739" LastEditorUserId="15311" LastEditDate="2020-03-12T10:54:02.690" LastActivityDate="2020-03-12T10:54:02.690" Title="What's the precision of a modern Inertial Measurement Unit, and how is it obtained?" Tags="&lt;navigation&gt;&lt;navaids&gt;&lt;inertial-nav-system&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2620" PostTypeId="1" AcceptedAnswerId="2621" CreationDate="2014-03-24T12:43:35.010" Score="27" ViewCount="54393" Body="&lt;p&gt;How does &lt;strong&gt;ILS&lt;/strong&gt; (Instrument landing system) work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Lxwt.jpg&quot; alt=&quot;ILS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I know it provides guidance to the runway by  two signals, one modulated at 90 Hz, the other at 150 Hz, but how the airplane lock on those signals?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uvfL2.jpg&quot; alt=&quot;ILS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Which system in the plane is responsible for the ILS? Is the autopilot responsible for it?&lt;/li&gt;&#xA;&lt;li&gt;If autopilot is used for an ILS approach, at what point does the pilot take manual control?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="14661" LastEditDate="2016-05-06T01:09:37.467" LastActivityDate="2016-05-06T01:09:37.467" Title="How does ILS (Instrument landing system) work?" Tags="&lt;navigation&gt;&lt;ils&gt;&lt;navaids&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2621" PostTypeId="2" ParentId="2620" CreationDate="2014-03-24T13:25:32.577" Score="26" Body="&lt;p&gt;The ILS works using two components, a localizer and a glideslope.  The frequencies for the localizer are between 108.1-111.95 MHz and the glide slope between 329.15-335.0 MHz.  These frequencies are the carrier waves that the modulation you mention takes place upon.  A pilot is only concerned with the localizer frequency as the navigation equipment knows the paired glideslope frequency for any given localizer frequency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equipment for transmitting the signals is pretty well described in your question.  The localizer antenna broadcasts two lobes down the length of the runway for a few miles (typically 18 nm, but some airports like LAX have a much longer serviceable distance).  The glideslope antenna sits around the 1000 ft touchdown zone markers on the runway, offset a little bit from the runway.  It broadcasts a its own two lobes centered around a 3 degree slope (this can vary by installation).  The glideslope is generally usable about 10 nm from the runway, but is generally not used that far out.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equipment in the plane responsible for using this signal comes in a few parts, an antenna, a radio and a navigation instrument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The localizer signal is received the antenna used for the normal navigation signals (VOR) and there will be an additional antenna for the glideslope signal.  These signals will first go to a nav radio, which the pilot uses to select the localizer frequency (or a VOR frequency).  If a localizer frequency is selected, the radio will also listen on a specific glideslope frequency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data from the radio is then sent to whatever instrument you are displaying the data on.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most primitive instrument is the VOR head with glideslope-type of needled navigation instrument.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tb0C3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A step up from that is an HSI, which is a bit more intuitive to fly and has better facilities for handling localizer back courses.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6g3zE.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the top end you have electronic primary flight displays that display data on a CRT or LCD screen.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eXZBL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basis of all of these are following two needles that are shown to the pilot.  One moves side to side and tracks the localizer, and the other moves up and down and tracks the glideslope.  If both of these are centered you are in the middle of both beams and on course.  The position of the needle is determined by which lobe of the transmitter is being received stronger than the other.  When both lobes are received equally the needle will be centered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To your last question, the pilot has control over the airplane for the entire approach.  The ILS does not take over the airplane.  The autopilot may be &lt;em&gt;slaved&lt;/em&gt; to follow either just the localizer, or both the localizer and glideslope, or the pilot may hand fly the approach.  In both cases however, the pilot is in control, not the ILS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ILS is usable for at least 10 miles from the antennae.  At many airports you will track the localizer portion of the signal much further out than this.  You will stop using the ILS normally at 200 ft above the ground, although there are special ILS approaches with lower minimum altitudes that require special equipment and training. The majority of ILS approaches however, require the pilot to observe certain visual cues before descending below 200 ft AGL.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="3504" LastEditDate="2015-01-15T17:34:25.053" LastActivityDate="2015-01-15T17:34:25.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2622" PostTypeId="1" CreationDate="2014-03-24T13:56:13.717" Score="9" ViewCount="1265" Body="&lt;p&gt;Recently I was checking in to a flight and was asked if I'd like a window or aisle seat as usual and choose a window seat. I was then told that there are no more window seats available but I could get an aisle seat without someone sitting next to me and then just take that window seat. The plane was an ATR-72 so the rows were 2+2 seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know about weight distribution to the front/back but I couldn't come up for a good reason to do this. What could be the reason for not giving me that apparently free window seat right away?&lt;/p&gt;&#xA;" OwnerUserId="744" LastEditorUserId="97" LastEditDate="2014-03-24T15:29:14.857" LastActivityDate="2014-10-22T11:11:28.580" Title="Seating distribution in passenger aircraft" Tags="&lt;passenger&gt;&lt;boarding&gt;" AnswerCount="2" CommentCount="19" ClosedDate="2014-10-24T13:07:14.700" ContentLicense="CC BY-SA 3.0" />
  <row Id="2623" PostTypeId="1" CreationDate="2014-03-24T14:29:30.450" Score="17" ViewCount="6229" Body="&lt;p&gt;I saw on news that the AAIB helped to locate the missing MH370 flight, saying that it ended up in Indian Ocean, with the help of a whole new technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering what kind of &quot;new technology&quot; it was?&lt;/p&gt;&#xA;" OwnerUserId="1744" LastEditorUserId="22550" LastEditDate="2018-11-22T02:26:19.633" LastActivityDate="2018-11-22T02:26:19.633" Title="How did the AAIB assist in locating MH370?" Tags="&lt;accidents&gt;&lt;uk&gt;&lt;mh370-incident&gt;&lt;aaib&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2624" PostTypeId="2" ParentId="2623" CreationDate="2014-03-24T14:42:13.220" Score="18" Body="&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/najibrazak/posts/10151954247230952&quot; rel=&quot;noreferrer&quot;&gt;The following statement&lt;/a&gt; has just been released today by the Prime Minister of Malaysia, in relation to the AAIB:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This evening I was briefed by representatives from the UK Air Accidents Investigation Branch (AAIB). They informed me that Inmarsat, the UK company that provided the satellite data which indicated the northern and southern corridors, has been performing further calculations on the data. &lt;strong&gt;Using a type of analysis never before used&lt;/strong&gt; in an investigation of this sort, they have been able to shed more light on MH370's flight path.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Based on their new analysis, Inmarsat and the AAIB have concluded that MH370 flew along the southern corridor, and that its last position was in the middle of the Indian Ocean, west of Perth.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;This is a remote location, far from any possible landing sites. It is therefore with deep sadness and regret that I must inform you that, according to this new data, flight MH370 ended in the southern Indian Ocean.&lt;/p&gt;&#xA;&lt;p&gt;We will be holding a press conference tomorrow with further details. In the meantime, we wanted to inform you of this new development at the earliest opportunity. We share this information out of a commitment to openness and respect for the families, two principles which have guided this investigation.&lt;/p&gt;&#xA;&lt;p&gt;Malaysia Airlines have already spoken to the families of the passengers and crew to inform them of this development. For them, the past few weeks have been heartbreaking; I know this news must be harder still. I urge the media to respect their privacy, and to allow them the space they need at this difficult time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It's not a &amp;quot;new technology&amp;quot; per se, but a new form of analysis. You might have heard recently that the aircraft &lt;a href=&quot;http://www.washingtonpost.com/blogs/worldviews/wp/2014/03/23/could-the-search-for-the-missing-malaysia-airlines-plane-have-gone-much-faster/&quot; rel=&quot;noreferrer&quot;&gt;responded to hourly &amp;quot;pings&amp;quot;&lt;/a&gt; from a satellite:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;British satellite company Inmarsat immediately began doing calculations based on a series of hourly &amp;quot;pings,&amp;quot; as the plane and one of the company's satellites tried to communicate with each other.&lt;/p&gt;&#xA;&lt;p&gt;Triangulating those pings seems to have given Inmarsat a pretty good idea of where the plane went, along one of two routes, to the north and to the south.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/i4KJx.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here is &lt;a href=&quot;http://www.washingtonpost.com/national/health-science/malaysia-airlines-flight-mh370-search-tests-limits-of-satellites/2014/03/20/47695b50-b063-11e3-9627-c65021d6d572_story.html&quot; rel=&quot;noreferrer&quot;&gt;some further information&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;About three hours after Flight MH370 went missing, Inmarsat, a British-based satellite company, began tracking the Boeing 777 through &lt;strong&gt;an on-board data system called Aero Classic&lt;/strong&gt;. Every hour, Inmarsat's satellites would try to communicate with the aircraft, pinging it with a computerized question asking, in effect, &amp;quot;Are you there?&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;For several hours, Flight MH370 responded &amp;quot;Yes, I am,&amp;quot; notifying engineers on the ground with a so-called handshake that the plane was still powered up.&lt;/p&gt;&#xA;&lt;p&gt;Using that series of pings, Inmarsat engineers and other analysts were able to piece together two broad, arcing regions where the plane could have been located when it last communicated with the satellite.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;Our engineers looked at the time between the handshakes, and they realized that the object wasn't stationary under a satellite but moving away from it,&amp;quot; Christopher McLaughlin, senior vice president of Inmarsat, said Thursday. &amp;quot;Over time, the engineers here recognized that there were a number of data points and that it had flown for several hours. We didn’t know if it was on the northern or southern corridor.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;More information on how Inmarsat determined MH370 flew along the Southern corridor specifically, will likely be released tomorrow at the press conference (as mentioned in Najib Razak's statement), which I gather is the information you're looking for.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-24T14:53:54.140" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2625" PostTypeId="5" CreationDate="2014-03-24T14:59:51.817" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-24T14:59:51.817" LastActivityDate="2014-03-24T14:59:51.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2626" PostTypeId="4" CreationDate="2014-03-24T14:59:51.817" Score="0" Body="For questions specifically relating to the United Kingdom." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-24T15:06:07.493" LastActivityDate="2014-03-24T15:06:07.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2627" PostTypeId="5" CreationDate="2014-03-24T15:09:09.107" Score="0" Body="&lt;p&gt;Aviation accident investigation in the United Kingdom started in 1912, when the Royal Aero Club published a report into a fatal accident at Brooklands Aerodrome, Surrey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AAIB was established in 1915 as the Accidents Investigation Branch (AIB) of the Royal Flying Corps (RFC). They are now a branch of the Department for Transport.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Accidents_Investigation_Branch&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aaib.gov.uk/&quot; rel=&quot;nofollow&quot;&gt;Official website&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-24T15:33:53.260" LastActivityDate="2014-03-24T15:33:53.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2628" PostTypeId="4" CreationDate="2014-03-24T15:09:09.107" Score="0" Body="The Air Accidents Investigation Branch investigates air accidents in the United Kingdom, and are based at Farnborough Airport." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-24T15:10:01.090" LastActivityDate="2014-03-24T15:10:01.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2629" PostTypeId="5" CreationDate="2014-03-24T15:10:39.163" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-24T15:10:39.163" LastActivityDate="2014-03-24T15:10:39.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2630" PostTypeId="4" CreationDate="2014-03-24T15:10:39.163" Score="0" Body="For questions relating to aviation accidents, or the avoidance thereof." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-24T15:34:13.363" LastActivityDate="2014-03-24T15:34:13.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2631" PostTypeId="5" CreationDate="2014-03-24T15:15:52.373" Score="0" Body="&lt;p&gt;An &lt;em&gt;instrument landing system&lt;/em&gt; (ILS) is a ground-based instrument &lt;a href=&quot;/questions/tagged/approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;approach&lt;/a&gt; system that provides precision guidance (thus making it a &lt;a href=&quot;/questions/tagged/precision-approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;precision-approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;precision-approach&lt;/a&gt;) to an aircraft approaching and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt; on a runway, using a combination of radio signals, and, in many cases, high-intensity lighting arrays to enable a safe landing during instrument meteorological conditions (&lt;a href=&quot;/questions/tagged/imc&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;imc&amp;#39;&quot; rel=&quot;tag&quot;&gt;imc&lt;/a&gt;), such as low ceilings or reduced visibility due to fog, rain, or blowing snow.&lt;/p&gt;&#xA;&lt;p&gt;An aircraft performing an ILS approach (colloquially known as &amp;quot;shooting&amp;quot; the approach&amp;quot;) is, at least initially, guided by two sets of radio beam transmitters:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;/questions/tagged/localizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;localizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;localizer&lt;/a&gt;, mounted slightly beyond the far end of the runway being approached, provides lateral guidance, hopefully keeping the aircraft from flying off to the side of the runway; it can also be used on its own for guidance during a nonprecision approach.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;/questions/tagged/glideslope&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glideslope&amp;#39;&quot; rel=&quot;tag&quot;&gt;glideslope&lt;/a&gt; transmitters are mounted next to the sides of the runway, usually ~1,000 feet past the threshold.  They provide vertical guidance, guiding the aircraft down a safe descent profile to the runway and (ideally) keeping it from hitting the ground before reaching the runway.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;It is also possible to have a localizer and glideslope that do &lt;em&gt;not&lt;/em&gt; lead directly to the runway itself (for instance, if high terrain in the vicinity of the airport makes a safe straight-in approach path impossible) but, rather, guide the aircraft down to a point reasonably close to the runway, from where the pilot can fly visually to a landing.  This is known as an &lt;em&gt;instrument guidance system&lt;/em&gt; (IGS); it is also sometimes called a &lt;em&gt;localizer-type directional aid&lt;/em&gt; (LDA), but the latter designation more properly refers to a type of approach with &lt;em&gt;only&lt;/em&gt; localizer guidance, and no glideslope.  IGS approaches are rare, as they are more complicated and difficult (sometimes &lt;em&gt;much&lt;/em&gt; more) to fly than a bog-standard ILS approach, and most airports do not have the severe terrain issues that require the use of an IGS.&lt;/p&gt;&#xA;&lt;p&gt;With most ILS approaches (and all IGS approaches), the pilot has to make visual contact with the runway, or the approach structures thereto, at or before a certain point in the approach, and then fly down visually to the runway; if the visibility is too low for the pilot to be able to do this, a &lt;a href=&quot;/questions/tagged/missed-approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;missed-approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;missed-approach&lt;/a&gt; is required.  To help with this, ILS-equipped runways generally have extensive &lt;a href=&quot;/questions/tagged/airport-lighting&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airport-lighting&amp;#39;&quot; rel=&quot;tag&quot;&gt;airport-lighting&lt;/a&gt; along the approach path leading up to the runway (the lower the visibility for which the runway is certified, the more extensive its approach lighting).&lt;/p&gt;&#xA;&lt;p&gt;This requirement comes about because even a good human pilot is - not to put too fine of a point on it - somewhat imperfect at manually guiding their airplane precisely along the ILS approach path in the absence of external visual cues.  A manually-flown ILS approach will generally approximate this ideal path fairly well, but still exhibits small deviations that create a slightly &amp;quot;bumpy&amp;quot;, uneven descent path; these small deviations could be fatal if they occurred very close to the ground.  To remedy this, British researchers (Great Britain being famous for its frequent, dense, opaque, aviation-impairing fogs) worked from the 1940s through the early 1960s on a system to allow the aircraft's &lt;a href=&quot;/questions/tagged/autopilot&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;autopilot&amp;#39;&quot; rel=&quot;tag&quot;&gt;autopilot&lt;/a&gt; to fly the aircraft down the ILS beams more precisely and accurately than any human pilot could hope to do - an &lt;a href=&quot;/questions/tagged/autoland&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;autoland&amp;#39;&quot; rel=&quot;tag&quot;&gt;autoland&lt;/a&gt; system.  The first airliner with autoland capability was the &lt;a href=&quot;/questions/tagged/hawker-siddeley-trident&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;hawker-siddeley-trident&amp;#39;&quot; rel=&quot;tag&quot;&gt;hawker-siddeley-trident&lt;/a&gt;, which entered service in 1964; autoland systems are ubiquitous on modern large airliners, and utterly &lt;em&gt;essential&lt;/em&gt; for operations in extremely low visibility (where the pilot might well be unable to make visual contact until the aircraft touches down, or even later).  Some autoland systems are even (theoretically) capable of guiding the aircraft through a safe touchdown and rollout in literal completely zero visibility, although no &lt;em&gt;airports&lt;/em&gt; are, as of yet, equipped for this (as making effective use of this capability would require some way to safely &lt;a href=&quot;/questions/tagged/taxi&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;taxi&amp;#39;&quot; rel=&quot;tag&quot;&gt;taxi&lt;/a&gt; in zero-zero visibility - ironically, a much more difficult problem to solve than that of merely &lt;em&gt;landing&lt;/em&gt; in these conditions!).&lt;/p&gt;&#xA;&lt;p&gt;An instrument approach procedure chart (or approach plate) is published for each ILS approach to provide the information needed to fly an ILS approach during instrument flight rules (IFR) operations. A chart includes the radio frequencies used by the ILS components or navaids and the prescribed minimum visibility requirements.&lt;/p&gt;&#xA;&lt;p&gt;ILS was to be replaced by the &lt;a href=&quot;/questions/tagged/microwave-landing-system&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;microwave-landing-system&amp;#39;&quot; rel=&quot;tag&quot;&gt;microwave-landing-system&lt;/a&gt; (MLS), developed in the 1970s and 1980s, which required far less in the way of equipment and was far more flexible than ILS, but, by the time MLS was ready for widespread deployment, GPS (the first &lt;a href=&quot;/questions/tagged/gnss&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gnss&amp;#39;&quot; rel=&quot;tag&quot;&gt;gnss&lt;/a&gt;) had come on the scene for civilian use. Since then WAAS approaches saw widespread use in USA for airports where an ILS would have been expensive, as well as LAAS/GBAS/GLS approaches in select major airports worldwide. (Note that &lt;a href=&quot;https://aviation.stackexchange.com/q/55180&quot;&gt;GLS is not RNAV&lt;/a&gt;.)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;For more information on ILS, see Wikipedia.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2020-11-27T18:23:24.783" LastActivityDate="2020-11-27T18:23:24.783" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2632" PostTypeId="4" CreationDate="2014-03-24T15:15:52.373" Score="0" Body="An instrument landing system (ILS) is a ground-based instrument approach system that provides precision guidance to an aircraft approaching and landing on a runway." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-08-22T05:46:43.327" LastActivityDate="2019-08-22T05:46:43.327" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2634" PostTypeId="2" ParentId="2605" CreationDate="2014-03-24T15:17:34.260" Score="10" Body="&lt;p&gt;It is possible with the old soviet wide-bodies; they have built-in stairs and even allow for luggage stowage by the crew during boarding. This autarky led to significantly increased weight, which meant that while these planes could land at remote destinations, they suffered from incompetitiveness in inter-airport service. And well, how often would one need a wide-body to bring 350 people into the middle of nowhere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many military transport aircraft, while having similar size as the aforementioned airliners, can fly tanks and/or equipment into remote areas. Fedex would never buy one, though... these machines are plain incompetitive in both acquisition and maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No plane requires a pushback vehicle in a remote destination, if said destination has a rotunda big enough for a full-turn, or if you have a runway with double the normal length.&lt;/p&gt;&#xA;" OwnerUserId="1745" LastEditorUserId="1745" LastEditDate="2014-03-24T15:25:43.763" LastActivityDate="2014-03-24T15:25:43.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2635" PostTypeId="5" CreationDate="2014-03-24T15:19:10.743" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-24T15:19:10.743" LastActivityDate="2014-03-24T15:19:10.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2636" PostTypeId="4" CreationDate="2014-03-24T15:19:10.743" Score="0" Body="Flight simulators are ground-based devices designed to replicates aspects of aircraft flight.&#xD;&#xA;They can range from full-motion airline cockpit simulators to relatively simple PC software, and are often used for flight training.&#xD;&#xA;" OwnerUserId="97" LastEditorUserId="64" LastEditDate="2016-07-08T18:01:38.740" LastActivityDate="2016-07-08T18:01:38.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2637" PostTypeId="5" CreationDate="2014-03-24T15:21:52.180" Score="0" Body="&lt;p&gt;Flights under Instrument Flight Rules (&lt;a href=&quot;/questions/tagged/ifr-navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ifr-navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;ifr-navigation&lt;/a&gt;) are usually assigned a &lt;strong&gt;Standard Instrument Departure (SID)&lt;/strong&gt; when departing an airport and a &lt;strong&gt;Standard Terminal Arrival Route (STAR)&lt;/strong&gt; when arriving at an airport. Not all airports use SIDs or STARs though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both procedures consist of a set of waypoints, optionally with altitude and/or speed restrictions, to organize the traffic flow in the area around the airport. A SID begins at the departure runway and ends at a waypoint where one or more airways can be joined. A STAR begins at such a waypoint and leads to an Initial Approach Fix (IAF), where an &lt;a href=&quot;/questions/tagged/approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;approach&lt;/a&gt; begins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about the departure and arrival procedures. When specifically asking about departures, use &lt;a href=&quot;/questions/tagged/departure-sid&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;departure-sid&amp;#39;&quot; rel=&quot;tag&quot;&gt;departure-sid&lt;/a&gt; instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further reading:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.skybrary.aero/index.php/SIDs_and_STARs&quot; rel=&quot;nofollow noreferrer&quot;&gt;skybrary.aero&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_instrument_departure&quot; rel=&quot;nofollow noreferrer&quot;&gt;SID on Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_terminal_arrival_route&quot; rel=&quot;nofollow noreferrer&quot;&gt;STAR on Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="33692" LastEditorUserId="33692" LastEditDate="2019-12-04T02:00:53.980" LastActivityDate="2019-12-04T02:00:53.980" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2638" PostTypeId="4" CreationDate="2014-03-24T15:21:52.180" Score="0" Body="A SID (Standard Instrument Departure) is a procedure for departing an airport and joining the airway structure. A STAR (Standard Terminal Arrival Route) is a procedure from the airway structure onto an approach." OwnerUserId="97" LastEditorUserId="33692" LastEditDate="2019-12-03T20:48:57.653" LastActivityDate="2019-12-03T20:48:57.653" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2639" PostTypeId="5" CreationDate="2014-03-24T15:22:35.337" Score="0" Body="&lt;p&gt;There's no formal, precise definition of an &quot;airliner&quot; but it's usually understood to mean any large aircraft used by a scheduled airline to carry &lt;a href=&quot;/questions/tagged/passenger&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;passenger&amp;#39;&quot; rel=&quot;tag&quot;&gt;passenger&lt;/a&gt;s and/or &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airliner is identified mainly by size: few people would call a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna Caravan&lt;/a&gt; an airliner, even though it's used in scheduled airline services in various parts of the world.  (A couple of things many people &lt;em&gt;would&lt;/em&gt; call a Caravan would be an &lt;em&gt;air taxi&lt;/em&gt; or &lt;em&gt;commuter plane&lt;/em&gt;, things that these small aircraft are quite good at.)  Airliners may have any type of engine: smaller, shorter-range airliners generally use &lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt;-powered (or, occasionally, &lt;a href=&quot;/questions/tagged/piston-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;piston-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;piston-engine&lt;/a&gt;-powered) &lt;a href=&quot;/questions/tagged/propeller&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;propeller&amp;#39;&quot; rel=&quot;tag&quot;&gt;propeller&lt;/a&gt;s, while large, fast, long-range airliners almost always use &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;s (nowadays, this means a &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt;, although the first jetliners used &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt; engines instead), and are called &lt;em&gt;jetliners&lt;/em&gt; as a result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for general questions about aircraft used for commercial airline operations, but if the question is about a specific make or model of aircraft, then it's better to use a more specific tag; e.g., &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt; or &lt;a href=&quot;/questions/tagged/airbus-a320&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a320&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a320&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airliner&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-10-21T06:37:43.103" LastActivityDate="2019-10-21T06:37:43.103" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2640" PostTypeId="4" CreationDate="2014-03-24T15:22:35.337" Score="0" Body="An airliner is a large, commercial aircraft operated by an airline for transporting people and/or cargo." OwnerUserId="97" LastEditorUserId="62" LastEditDate="2014-09-11T16:06:28.950" LastActivityDate="2014-09-11T16:06:28.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2641" PostTypeId="5" CreationDate="2014-03-24T15:25:42.360" Score="0" Body="&lt;p&gt;A &lt;em&gt;cockpit voice recorder&lt;/em&gt; (CVR) is one of two &lt;a href=&quot;/questions/tagged/flight-recorders&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-recorders&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-recorders&lt;/a&gt; (popularly, though inaccurately, known as &quot;black boxes&quot;), used to record audio in the cockpit to aid in &lt;a href=&quot;/questions/tagged/accident-investigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;accident-investigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;accident-investigation&lt;/a&gt;s; the other flight recorder is the &lt;a href=&quot;/questions/tagged/flight-data-recorder&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-data-recorder&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-data-recorder&lt;/a&gt;, which records aircraft parametric data.  Some newer recorders store both audio and parametric data in a single memory module (but still have two separate recorders); this provides redundancy, as, even if one recorder is lost or destroyed, all audio and parametric data can still be recovered from the other recorder.  Such a combined CVR/FDR is known as a &lt;em&gt;cockpit voice and data recorder&lt;/em&gt;, or CVDR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CVRs typically have multiple channels of audio data, each recording audio from different sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One sound channel is connected to the &lt;em&gt;cockpit area microphone&lt;/em&gt; (CAM), a microphone (usually mounted in the cockpit roof) which records all sounds audible in the cockpit, both spoken (such as flightcrew conversations or &lt;a href=&quot;/questions/tagged/radio-communications&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radio-communications&amp;#39;&quot; rel=&quot;tag&quot;&gt;radio-communications&lt;/a&gt;) and not (such as engine and wind noises or the sounds of things exploding or breaking apart).  The CAM channel has the advantage that it records &lt;em&gt;everything&lt;/em&gt; that can be heard in the cockpit, but the disadvantages that all this sound is mixed together (rather than different sounds being recorded separately) and the flightcrew's voices can sometimes be difficult to make out against the background noise.&lt;/li&gt;&#xA;&lt;li&gt;The other channels record data from the microphones and earphones of the pilots' headsets; this provides a very-high-quality recording of everything the flightcrew say (or hear over the radio), at the expense of not recording non-voice sounds.  A common strategy is to provide two or three channels of single-source audio (one for the headset audio from each of the &lt;a href=&quot;/questions/tagged/pilots&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pilots&amp;#39;&quot; rel=&quot;tag&quot;&gt;pilots&lt;/a&gt;, plus sometimes a third for the cockpit observer or &lt;a href=&quot;/questions/tagged/flight-engineer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-engineer&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-engineer&lt;/a&gt; position on aircraft so equipped), plus a single longer-duration channel containing the audio data from all the headsets mixed together.  The headset-audio channel(s) are also sometimes known as the &quot;hot microphone&quot; channel(s) (designated HOT in CVR transcripts), as the headset microphones on most modern aircraft are voice-activated (or &quot;hot&quot;), being active only when spoken to (this improves the quality of the resulting audio by keeping extraneous noise from being recorded when nobody's talking).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Where an aircraft is required to carry a CVR and utilises digital communications, the CVR is required to record such communications with air traffic control unless this is recorded elsewhere. As of 2008, it is an FAA requirement that the recording duration is a minimum of two hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_recorder#Cockpit_voice_recorder&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-09-06T06:55:24.017" LastActivityDate="2019-09-06T06:55:24.017" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2642" PostTypeId="4" CreationDate="2014-03-24T15:25:42.360" Score="0" Body="A cockpit voice recorder (CVR) is one of two flight recorders (&quot;black boxes&quot;), used to record audio in the cockpit for the purpose of investigation of accidents and incidents." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-03-31T01:17:48.547" LastActivityDate="2019-03-31T01:17:48.547" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2644" PostTypeId="1" AcceptedAnswerId="2710" CreationDate="2014-03-24T17:29:06.883" Score="12" ViewCount="8453" Body="&lt;p&gt;I am searching some airports &lt;a href=&quot;http://ourairports.com/data/&quot;&gt;databases&lt;/a&gt; and I find some airports with the same IATA code with different ICAO codes. Is it mistake in the database? Is it OK?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Marine_Corps_Air_Station_Beaufort&quot;&gt;Beaufort MCAS - Merritt Field&lt;/a&gt; (ICAO KNBC IATA BFT)  &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Beaufort_County_Airport&quot;&gt;Beaufort County Airport&lt;/a&gt;       (ICAO KARW IATA BFT)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: Another example;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Paamiut_Airport&quot;&gt;Paamiut Airport&lt;/a&gt;    (ICAO BGPT IATA JFR )&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.greatcirclemapper.net/en/airport/JFR-BGFH-paamiut-heliport.html&quot;&gt;Paamiut Heliport&lt;/a&gt;   (ICAO BGFH IATA JFR )&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Another example with &lt;a href=&quot;https://www.google.com/maps/dir/Aeropuerto+Desierto+de+Atacama,+Chile/%27%27/@-27.3325889,-70.597611,19751m/data=!3m1!1e3!4m11!4m10!1m5!1m1!1s0x96bd5e4dcd109157:0x3f2931bf6908b85a!2m2!1d-70.779167!2d-27.261389!1m3!2m2!1d-70.4140278!2d-27.2967778&quot;&gt;40 km&lt;/a&gt; between them:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Desierto_de_Atacama_Airport&quot;&gt;Desierto de Atacama&lt;/a&gt; (IATA: CPO – ICAO: SCAT)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Chamonate_Airport&quot;&gt;Chamonate&lt;/a&gt;           (IATA: CPO – ICAO: SCHA)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1019" LastEditorUserId="97" LastEditDate="2014-03-25T18:01:32.767" LastActivityDate="2014-03-26T13:26:08.573" Title="Can two airports have a different ICAO code but share the same IATA code?" Tags="&lt;airport&gt;&lt;icao&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2645" PostTypeId="1" AcceptedAnswerId="2647" CreationDate="2014-03-24T18:35:27.623" Score="5" ViewCount="648" Body="&lt;p&gt;The question is a little open, but I'm &lt;strong&gt;wondering how many TCAS resolutions (i.e. the serious type) occur every week or month over sizeable region like the United States or Europe.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-03-24T19:19:42.700" Title="How frequent are TCAS resolution events?" Tags="&lt;safety&gt;&lt;tcas&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2646" PostTypeId="1" AcceptedAnswerId="2650" CreationDate="2014-03-24T19:02:39.330" Score="14" ViewCount="6172" Body="&lt;p&gt;Here's the scenario:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight starts night VFR, with broken ceiling at destination (class C airspace) and expected to improve according to the pre-flight abbreviated briefing. I'm IFR certified but prefer to stay VFR to dodge icy clouds along the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I'm about 15nm from my destination, talking to approach control, and the ATIS calls the ceiling overcast: it's apparent I'll have to file IFR one way or another. Approach is busy, but not overwhelmed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best way to handle this situation on the radio? I have the ATIS, picked an approach and have a squawk code (advisories):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a). Do I ask approach directly for the IFR clearance, and what is the officially sanctioned phraseology? Also: do I have to cancel IFR when I'm on the ground/see the runway, i.e., is the clearance to descend thru the layer and shoot an approach a 'real' IFR flight plan?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b). Ask approach if I can change frequency to FSS, file with them, then return to approach to pickup the clearance (and cancel when on the ground/view of runway)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c). Other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did read &lt;a href=&quot;https://aviation.stackexchange.com/questions/1361/how-do-you-request-a-pop-up-ifr-clearance&quot;&gt;How do you request a &quot;pop up&quot; IFR clearance?&lt;/a&gt;. In my scenario I have the time to call FSS, there is no emergency, I'm on flight following and could complete (b) if that's the best way to go.&lt;/p&gt;&#xA;" OwnerUserId="1750" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2021-03-10T13:49:18.073" Title="How should I request an IFR approach at the end of a VFR flight?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2647" PostTypeId="2" ParentId="2645" CreationDate="2014-03-24T19:19:42.700" Score="6" Body="&lt;p&gt;I found a &lt;a href=&quot;https://www.ll.mit.edu/publications/journal/pdf/vol16_no2/16_2_04Kuchar.pdf&quot;&gt;very interesting paper&lt;/a&gt; from 2007 that analyzed TCAS performance. They analyzed recorded data to come up with 1 RA per 116 flight hours.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Over this time period, monitoring took place for approximately 190&#xA;  days, and roughly 200,000 Mode S flight hours were observed within the&#xA;  sensor’s 60 nmi coverage area. We observed a total of 1725 RA events,&#xA;  corresponding to an average of 9 RAs per day, or approximately one RA&#xA;  every 116 flight hours.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They explain that the data was taken in the Boston area, so the high amount of traffic contributes to the high number of RAs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/297292/&quot;&gt;This thread&lt;/a&gt; on Airliners.net suggest differently, at least in the sense that for those pilots it is a matter of a few over years, depending on where they typically fly.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-24T19:19:42.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2648" PostTypeId="2" ParentId="2646" CreationDate="2014-03-24T19:22:06.303" Score="4" Body="&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/q/1361/52&quot;&gt;this question about popup IFR&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Back in the day&quot; (began the grey bearded geezer who hasn't flown IFR in a long time), you'd just tell Approach something like &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Approach, Cessna 123, (possibly insert location info),  request IFR, approach XYZ&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule I was taught is &quot;who are you, where are you, what do you want&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You already have a squawk &amp;amp; you're already talking, so it should be simple.  I'd expect to hear back &quot;Cessna 123, IFR approved, maintain current heading, ...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I recall correctly, Tower or Ground closes your IFR plan for you - they know you landed.&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-03-24T19:22:06.303" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2649" PostTypeId="2" ParentId="2623" CreationDate="2014-03-24T20:02:39.940" Score="1" Body="&lt;p&gt;From what I can deduce they compared the redshift of the pings to other aircraft flying the proposed routes and were able to eliminate the north hypothesis.&lt;/p&gt;&#xA;" OwnerUserId="1751" LastEditorUserId="97" LastEditDate="2014-03-25T12:48:52.540" LastActivityDate="2014-03-25T12:48:52.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2650" PostTypeId="2" ParentId="2646" CreationDate="2014-03-24T20:09:51.750" Score="21" Body="&lt;p&gt;Since you are already on flight following you are already in the system (ATC has a flight strip for you and a datablock on the radar).  Just call ATC and ask them for IFR to your destination.  Don't bother asking for a frequency change to FSS to file a flight plan, only to come right back on and ask to pick it up.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Austin Approach, Cessna 12345, request IFR to Austin&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Since you have flight following ATC already knows your type, equipment suffix, location and altitude, so don't repeat it.  ATC should ask&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Cessna 12345, verify you are &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap10_section_2.html#KsI212JACK&quot; rel=&quot;nofollow noreferrer&quot;&gt;qualified for and capable of&lt;/a&gt; IFR flight?&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and after you (hopefully) reply in the affirmative will issue:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Cessna 12345, cleared to the Austin Bergstrom Airport via fly heading 270, vector to ILS Runway 35-Right final approach course, maintain 2000.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you are already in the approach environment you probably won't get a climb to an IFR altitude, you'll just be given whatever altitude they need for the arrival flow.&lt;/p&gt;&#xA;&lt;p&gt;This method is faster than filing with FSS and easier for ATC (they don't have to approve a frequency change, wait around for you to file, then have you come back and wait further while your flight plan works its way through the system).  However, bear in mind that none of the &amp;quot;extra&amp;quot; search-and-rescue information you would give to FSS (fuel and souls on board, emergency equipment, filed alternate, aircraft color and markings) will be recorded.&lt;sup&gt;2&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;If you are landing at a towered airport you will not need to &lt;a href=&quot;https://aviation.stackexchange.com/a/84016/54557&quot;&gt;cancel IFR&lt;/a&gt; as the local controller will do this for you.  If you are landing at a non-towered airport you will need to radio ATC or FSS or telephone FSS to cancel your IFR service.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Footnotes&lt;/h3&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;This is a relatively new requirement after a non-IFR-rated pilot accepted an IFR clearance and &lt;a href=&quot;https://www.youtube.com/watch?v=ROCUheRin9U&quot; rel=&quot;nofollow noreferrer&quot;&gt;subsequently crashed.&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;Some facilities will have you rattle all that information off on the controller's frequency or a separate unused frequency and then mark that down in the flight plan remarks, just to have it on the tapes in case it's needed. If you're only 15 miles from your destination they probably won't do this but it's a possibility.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="54557" LastEditDate="2021-03-10T10:00:20.553" LastActivityDate="2021-03-10T10:00:20.553" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2651" PostTypeId="1" CreationDate="2014-03-24T20:19:05.423" Score="3" ViewCount="809" Body="&lt;p&gt;Why is it that black boxes don't float? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I gather the answer is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So they will not float away from a water crash site. The ping can be heard underwater with sonar. Finding the ping, finds the site.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But why not have two black boxes one that floats and one that stays with the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That way if a plane is lost at sea, if we find the black box floating, we could use the data to find the other black box and the crash site. Plus the benefits of having a redundancy are enormous.&lt;/p&gt;&#xA;" OwnerUserId="1752" LastActivityDate="2014-03-24T20:25:43.613" Title="Why don't they have two black boxes?" Tags="&lt;safety&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-03-25T10:21:40.017" ContentLicense="CC BY-SA 3.0" />
  <row Id="2652" PostTypeId="2" ParentId="2651" CreationDate="2014-03-24T20:25:43.613" Score="3" Body="&lt;p&gt;The added weight, space, and complexity of a second recorder have to be taken into account, and all are very important for an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are just interested in location, then there could just be a simple beacon designed to float. Although less, this will still have the above costs. And you have to design something light enough to float, sturdy enough to survive an extremely violent crash, yet still be a functional electronic device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering that the situation of a lost aircraft at sea is fairly rare, it is questionable whether the benefits justify the costs.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-24T20:25:43.613" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2653" PostTypeId="2" ParentId="2605" CreationDate="2014-03-24T20:43:55.697" Score="13" Body="&lt;p&gt;The venerable DC-9 was designed to service small airports out away from the hubs with a minimum of equipment.  The engines were up on the fuselage rather than under the wing so that the landing gear legs could be short, lowering the fuselage.  This result let the baggage compartment be reached without the usual portable conveyor belt.  Air stairs were built into the fuselage and were deployed horizontally, until they lowered the outboard end to the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gravel kicked up by the nosegear and then ingested by the engines became a problem so the DC-9s and the MD-80s that followed had a gravel deflector shield mounted on the nosewheel.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the DC-9 is not a Boeing or Airbus in the original question (ok, ok, lets agree to set aside the Boeing 717 that was the final iteration of the DC-9/MD-80 family) but the principle endures:  Large commercial airliners can be designed to function nicely without a ton of ground support. However, the vast majority of commercial airports are well equipped to handle planes, so the designers of the planes have in many cases left all that stuff off the planes to save weight, complexity, and space.  So the ground support is necessary.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-03-24T20:49:20.287" LastActivityDate="2014-03-24T20:49:20.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2654" PostTypeId="1" CreationDate="2014-03-24T20:53:51.513" Score="2" ViewCount="67" Body="&lt;p&gt;Can an FDR on a Boeing 777 be interfered with or vandalised during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this has happened on MH370 then the black boxes may not yield any data if found.&lt;/p&gt;&#xA;" OwnerUserId="1754" LastEditorUserId="22550" LastEditDate="2018-12-10T20:56:54.307" LastActivityDate="2018-12-10T20:56:54.307" Title="Can the FDR be interfered with in-flight?" Tags="&lt;flight-data-recorder&gt;&lt;mh370-incident&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2014-03-24T21:38:04.600" ContentLicense="CC BY-SA 3.0" />
  <row Id="2655" PostTypeId="1" AcceptedAnswerId="2658" CreationDate="2014-03-24T21:25:59.973" Score="18" ViewCount="18964" Body="&lt;p&gt;In too many cases of unfortunate incidents, hunting for FDR (or CVR also) is a major challenge.&lt;sup&gt;1&lt;/sup&gt; There are many or all answers recorded on that device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why a locator (GPS linked) cannot be included in the black box? It has its battery which runs for several days and very rigid outer shell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ordinary cell phones are GPS enabled which pinpoint their location with the accuracy of a couple of feet. So why there cannot be a more sophisticated technology added to the black boxes?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;em&gt;I am aware that most of FDRs/CVRs are &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders&quot; rel=&quot;nofollow&quot;&gt;eventually recovered&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-12T15:00:16.313" LastActivityDate="2014-12-12T15:00:16.313" Title="Why don't black boxes have their own GPS?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2656" PostTypeId="2" ParentId="2655" CreationDate="2014-03-24T21:34:13.390" Score="7" Body="&lt;p&gt;If you can receive a signal from the device, then you can already home in on where that signal is coming from. The signal does not need to include the position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS would also be of limited use. In most scenarios, it would probably be unable to receive a signal underneath water, terrain, weather, and wreckage. The GPS and antenna would also have to survive in order to function.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-24T21:34:13.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2657" PostTypeId="2" ParentId="2655" CreationDate="2014-03-24T21:46:24.953" Score="4" Body="&lt;p&gt;Actually, modern &lt;a href=&quot;http://en.wikipedia.org/wiki/Emergency_Locator_Transmitter#Beacon_Operation&quot;&gt;406 Mhz ELT's&lt;/a&gt; do have GPS built-in and they transmit their location to satellites when activated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they are required by US regulations, it would be redundant to require the black box to have its own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;GPS-based, registered&lt;/strong&gt;&lt;br&gt;&#xA;  The most modern 406 MHz beacons with GPS&#xA;  (US$ $300+ in 2010) track with a precision of 100 meters in the 70% of&#xA;  the world closest to the equator, and send a serial number so the&#xA;  responsible authority can look up phone numbers to notify the&#xA;  registrator (e.g. next-of-kin) in four minutes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The GPS system permits stationary, wide-view geosynchronous&#xA;  communications satellites to enhance the doppler position received by&#xA;  low Earth orbit satellites. EPIRB beacons with built-in GPS are&#xA;  usually called GPIRBs, for GPS Position-Indicating Radio Beacon or&#xA;  Global Position-Indicating Radio Beacon.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, rescue cannot begin until a doppler track is available. The&#xA;  COSPAS-SARSAT specifications say [7] that a beacon location is not&#xA;  considered &quot;resolved&quot; unless at least two doppler tracks match or a&#xA;  doppler track confirms an encoded (GPS) track. One or more GPS tracks&#xA;  are not sufficient.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-24T21:46:24.953" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2658" PostTypeId="2" ParentId="2655" CreationDate="2014-03-24T22:07:44.983" Score="22" Body="&lt;p&gt;First let's and define what &quot;too many cases&quot; means in terms of cold, hard, unfeeling numbers (as best we can):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia has a list (admittedly incomplete) of crashes where the CVR/FDR was not recovered&lt;/a&gt;. There are 16 crashes listed. I'll further add Air France 447 (which took &quot;a long time&quot; to find), and MH370 (which is currently unrecovered), bringing the total to 18.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Wikipedia admits their list is incomplete I'll double-and-round that in the name of being pessimistically conservative and say that since 1965 there have been 50 cases where it has taken &quot;a long time&quot; to recover the flight recorders (or they were never recovered). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aviation_accidents_and_incidents#Aircraft_Crashes_Record_Office_.28ACRO.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;In a single year there can be over 100 &quot;incidents&quot;&lt;/a&gt;. Even if we assume the CVR/FDR data wouldn't be useful for all of them there are still many hundreds (if not thousands) of incidents since 1965 where the cockpit voice recorder and/or flight data recorders have been recovered along with other wreckage or damaged airframes - often within a matter of days or hours (as soon as investigators can &lt;em&gt;get to the wreckage&lt;/em&gt;). That's a pretty good track record.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One could certainly argue (legitimately) that &quot;one unrecovered flight recorder is too many&quot;, and indeed the goal is to always find the recorders and analyze their contents.&lt;br&gt;&#xA;If we're being realistic about this though we're going to have to accept the fact that &lt;em&gt;sometimes you're just not going to recover the recorders&lt;/em&gt;: Aircraft crashes are messy, high-energy affairs and often involve inhospitable recovery environments like &quot;the bottom of the ocean&quot;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If someone has better statistics close at hand I would love to review them and update this answer. Otherwise, it should be obvious that the above is an &lt;em&gt;extremely&lt;/em&gt; rough off-the-cuff estimate, and should not be taken for any research or investigative purposes.&lt;br&gt;&#xA;  In case it's not obvious - well I just said it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, to the meat of your question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically you &lt;em&gt;could&lt;/em&gt; include a locator beacon in the CVR or FDR - incorporating a &lt;a href=&quot;http://en.wikipedia.org/wiki/Distress_radiobeacon#Digital_mode:_406.C2.A0MHz_beacons&quot; rel=&quot;nofollow noreferrer&quot;&gt;406MHz ELT&lt;/a&gt; into the black box design is possible (you could even add a GPS to encode the device's location, though it would be of limited additional value with the inherent location accuracy of the 406MHz locator signal and satellite search system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So why don't we do it?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/2657/64&quot;&gt;Lnafziger pointed out&lt;/a&gt;, airliners are already required to carry emergency locator transmitters - in any case where such a beacon would function including one in the CVR/FDR would be redundant with existing equipment in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further practical problems arise when you consider &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_data_recorder#Design&quot; rel=&quot;nofollow noreferrer&quot;&gt;the kind of abuse a &quot;black box&quot; is subject to&lt;/a&gt; -- These things need to survive a crash (up to 3400 Gs), crush forces, fire, and immersion in water under pressure.&lt;br&gt;&#xA;Your typical distress beacon requires an antenna and a view of the sky, both of which would be in serious doubt after a crash:  The black box may be inside or under wreckage, required external antennas may have been torn off or burned away, and distress beacon signals are unlikely to be received if the recorder is under water (this is why current generation recorders have sonar &quot;pingers&quot; to assist in locating them).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To easily illustrate the sort of problem radio devices have with &quot;stuff&quot; between them and the sky, try this experiment: Take your cell phone, wrap it in aluminum foil to simulate the skin of a plane, put it in a zip-lock bag, and take it to the bottom of a pool. I bet you won't be able to get a call on that phone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Given the numerous failure modes (all of which are fairly high-probability in a real-world crash scenario), and the fact that we &lt;em&gt;usually&lt;/em&gt; have a pretty good idea of where an aircraft is when a crash does happen, there isn't much to be gained by including additional locator technology in the CVR/FDR designs at this time - it just adds more components that would need periodic testing and recertification to ensure they are functioning properly and would activate appropriately in the event of a crash, while not appreciably improving our odds of finding the recorders.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-03-24T22:07:44.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2660" PostTypeId="2" ParentId="2623" CreationDate="2014-03-24T22:31:42.003" Score="9" Body="&lt;p&gt;Like most geostationary satellites, Inmarsat 3-F1 is not in a truly fixed orbit relative to the earth: it drifts a few degrees north and south.  Knowing this, and more importantly the speed it is drifting north or south, lets them refine their already very good doppler measurements - if you assume the northern path, you have to assume MH370 had constantly varying airspeed - if you assume the southern route, the airspeed comes out constant.&lt;/p&gt;&#xA;" OwnerUserId="1757" LastActivityDate="2014-03-24T22:31:42.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2661" PostTypeId="2" ParentId="2620" CreationDate="2014-03-24T22:34:46.903" Score="8" Body="&lt;p&gt;To add a little more detail on the receiver side and how it's used; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The localiser and glideslope signals are transmitted on different frequencies (the &quot;carrier&quot; frequency) and these are filtered out to leave a mix of 90Hz and 150Hz for each one.  The 90 and 150 are then filtered out separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have more 90Hz than 150Hz, you are too far left on the localiser or, too high on the glideslope. The guidance indicator is just a display of the ratio between 90Hz and 150Hz.  A 50% ratio means just right!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On your question of &quot;for how long?&quot;, a common procedure (it might be different for a particular field or approach) is to fly towards the centre line of the localiser and below the glideslope at an angle of about 30 degrees to intercept the localiser at about 10 miles out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC will vector the aircraft to this point (e.g.  &lt;code&gt;Speedbird 93, descend and maintain 1500 feet, turn left heading 300 degrees.  Cleared ILS approach 27L report established&lt;/code&gt;).  The autopilot is usually in approach mode meaning that it will capture the localiser, and in turn the glideslope, and follow the ILS down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the localiser is captured, the autopilot will turn the aircraft onto the centre line and the pilot reports established back to ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is normal procedure to capture the localiser at a height lower than the glideslope at the point of capture so that you capture the glideslope from below.  This is for safety.  If you captured the glideslope from above, then the aircraft may well descend through the glideslope then level out to recapture.  Descending below the glideslope, at what might well be hundreds of feet per minute, is not good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, most procedures call for a stabilised approach (correctly configured, following the ILS, speed correct, check lists complete, no large deviations in course, height or power settings) by 1000' or go around.  Many pilots, depending on their airlines procedures and conditions, will disconnect the autopilot for the last 1000 feet, sometimes to give practice to the first officer. Some aircraft are cleared all the way down (autoland) but that will also depend on company operations, crew currency and local procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&#xA;I deliberately left out the harmonics.  I figured I only had one page ;)&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-12-31T19:45:11.273" LastActivityDate="2015-12-31T19:45:11.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2662" PostTypeId="2" ParentId="2623" CreationDate="2014-03-24T22:38:37.257" Score="6" Body="&lt;p&gt;Apparently the satellite is not exactly geostationary but describes a small 8 figure over a roughly 24 hour cycle, and it is known which direction it is moving towards at any given time. I think it is in fact the Doppler effect of the combined satellite+plane movement which allowed them to distinguish between the north and the south paths. So, for instance, if the satellite was moving north at a given time one would expect an increased red shift if the plane was flying south and a reduced one if flying north.&lt;/p&gt;&#xA;" OwnerUserId="1758" LastActivityDate="2014-03-24T22:38:37.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2663" PostTypeId="2" ParentId="1314" CreationDate="2014-03-25T00:29:24.347" Score="3" Body="&lt;p&gt;As indicated in the other answers, &quot;remain clear&quot; means just that, and can happen when congested (as already indicated by @Lnafziger). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One approach that I take in the Bay Area to have a greater chance of getting into Oakland's Class C or SFO's Class B is to get a squawk code (with a flight following request) from another facility first, then get handed over. That way, it's just a matter of a frequency change and a hand-over. E.g. &quot;N12345Z on frequency at 2000&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;State to the first facility (squawk code assigner) what your intentions are so that they can give you the correct squawk code (they are different sometimes depending on whether you need to be handed off to another facility)&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2014-04-21T21:51:08.933" LastActivityDate="2014-04-21T21:51:08.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2664" PostTypeId="1" AcceptedAnswerId="2673" CreationDate="2014-03-25T00:37:31.323" Score="10" ViewCount="693" Body="&lt;p&gt;Are there any FAA regulations concerning wireless Bluetooth headsets in the cockpit of any aircraft? Moreover, I'm interested in finding out if the Bluetooth protocol (IEEE 802.15.1) will adversely affect any aircraft avionics in terms of radio interference or other Electromagnetic Interference (EMI). If anyone has any experience with this, thoughts and comments would be greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="1759" LastEditorUserId="1696" LastEditDate="2015-02-16T22:19:14.243" LastActivityDate="2015-02-16T22:19:14.243" Title="Are there regulations or adverse effects regarding Bluetooth in the cockpit?" Tags="&lt;radio-communications&gt;&lt;avionics&gt;&lt;cockpit&gt;&lt;electronics&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2665" PostTypeId="2" ParentId="2623" CreationDate="2014-03-25T01:10:19.290" Score="2" Body="&lt;p&gt;CNN replay of the analysis showed that the south route had the plane approaching the satellite like a train approaching an observer then moving away from the satellite for the rest of that route.&#xA;The doppler shift therefore resulted in a higher frequency initially then a lower frequency as the plane traveled south. If the plane had went north the doppler shift would only cause the frequency to get lower and lower much like the sound of a train traveling only away from an observer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume they could also take into account the slight figure 8 that the satellite takes from the 64.5 degree nominal position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also they indicated they calibrated the data to known past flights by 777's going south vs north.&lt;/p&gt;&#xA;" OwnerUserId="1761" LastActivityDate="2014-03-25T01:10:19.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2667" PostTypeId="1" CreationDate="2014-03-25T01:17:13.843" Score="7" ViewCount="364" Body="&lt;p&gt;If the pilots, crew and passengers had all passed out from an unexplained result of gradual de-pressurization, and ground personnel were somehow aware of this scenario, would there have been anything that could of been done to save the plane and people before the fuel ran out?&lt;/p&gt;&#xA;" OwnerUserId="1763" LastEditorUserId="3504" LastEditDate="2015-03-23T11:37:32.293" LastActivityDate="2015-03-23T11:37:32.293" Title="What can ground personnel do in the event of in-flight depressurization?" Tags="&lt;emergency&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2668" PostTypeId="2" ParentId="1436" CreationDate="2014-03-25T01:33:01.513" Score="8" Body="&lt;p&gt;The only thing you need is the tail number. Google it :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, the wingtips are one thing that could be used to differentiate between aircraft having the same number of engines. From &lt;a href=&quot;http://boardingarea.com/unroadwarrior/2011/03/28/wing-tips-boeing-v-airbus/&quot; rel=&quot;noreferrer&quot;&gt;The Boarding Area&lt;/a&gt; blog:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Regular:&lt;/strong&gt; These are the traditional wings. There are no tips at the&#xA;   end. They are seen on all Boeing aircraft except the 747 and none of&#xA;   the Airbus aircraft. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Blended Winglets:&lt;/strong&gt; Winglets are a new type of wingtip that are used primarily to increase fuel efficiency. Boeing has winglets that can be seen on their single aisle aircraft – 737 and 757. All Southwest aircraft have wingtips. I have not seen wingtips on Boeing widebody aircraft, but I am told they are coming soon (Boeing 767 and 777).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ddHVzm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Airbus recently announced that they will start adding winglets to their new A319, A320, A321 aircraft. They are calling them Sharklets. This will make telling them apart tough.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Wingtip Fence:&lt;/strong&gt; These are the relatively tiny triangular winglets one can see in the attached picture. All current A318, A319, A320, A321 and A380 aircraft have these devices. This makes telling these aircraft from others real easy.&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/V76Osl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Wingtip Endplates:&lt;/strong&gt; These are seen on A330, A340 and Boeing 747 aircraft. They are not upturned like winglets, but at an angle.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aAgFH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="193" LastEditorUserId="193" LastEditDate="2014-03-25T01:39:50.817" LastActivityDate="2014-03-25T01:39:50.817" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2669" PostTypeId="2" ParentId="2667" CreationDate="2014-03-25T01:33:50.277" Score="9" Body="&lt;p&gt;No.  If the crew and passengers have all passed out due to lack of oxygen and the plane has not been commanded for a descent, they will never wake up.  This has happened before, e.g. the &lt;a href=&quot;http://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash&quot;&gt;Payne Stewart fatal accident&lt;/a&gt;.  In cruise flight an autopilot is only commanded to perform lateral navigation and absent instructions from the crew to initiate a descent it will fly to its last fix and then maintain its current heading, all the while maintaining altitude.  When fuel is exhausted it will maintain altitude at the expense of airspeed until the stick shaker activates, disconnecting the autopilot.  Absent the pilots input, the stick pusher should next activate to forcefully prevent a stall.  You'll probably get some oscillations in pitch but ultimately a steep descent that even if the (literally) brain dead crew could somehow wake would not give them time to act.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While ground crews can get data from the airplane and can attempt to contact the crew, they cannot remotely control the airplane so the best they could do, if aware, is watch.  They could perhaps get a fighter scrambles to intercept and visually inspect the cockpit, but that still would not allow them to alter the outcome (just verify the scenario).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this scenario is much more likely to happen in an extreme depressurization event in which the crew is unable to don O2 masks in time.  A slow gradual depressurization will give plenty of warning as the cabin begins to climb and automated sensors start complaining.  In the EMB-145 you'll start getting aural warnings when the cabin exceeds 10,000 ft pressure altitude and somewhere shortly above that you'll get master caution alarms and automatic pax 02 deployment.  These altitudes should give the crew ample warning before becoming hypoxic (you can reach these altitudes for limited time with no supplemental O2 in a Cessna 172 for example).  Even at cruise, it only takes a few minutes to get the plane back down to 10,000 ft and as such a slow gradual depressurization should not pose a threat unless multiple warning systems are malfunctioning.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-03-25T01:33:50.277" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="2671" PostTypeId="1" AcceptedAnswerId="2672" CreationDate="2014-03-25T02:56:36.990" Score="28" ViewCount="45549" Body="&lt;p&gt;Right after take off 1-2 minutes into flight I get this stomach drop &quot;roller coaster&quot; feeling for split second.  It freaks people out thinking they are about to crash!  Why is that??&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="97" LastEditDate="2014-03-25T11:13:03.267" LastActivityDate="2019-03-06T06:27:23.340" Title="Why do I get that funny stomach drop feeling right after takeoff?" Tags="&lt;passenger&gt;&lt;takeoff&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2672" PostTypeId="2" ParentId="2671" CreationDate="2014-03-25T03:03:40.740" Score="37" Body="&lt;p&gt;It happens when the airplane levels off after takeoff, usually either at the first assigned altitude or at a safe altitude where it will be accelerated in order to retract the flaps.   The feeling is a result of negative vertical acceleration.  It can also happen at other times during the flight, such as during turbulence or when starting a descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically you and the airplane are both in a steady climb and when the aircraft levels off you continue to move up faster so it (via the seatbelt) keeps you at its same level and decelerates your own personal vertical climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is just like the feeling you get in a roller coaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My wife calls it a wee-hill!  :-)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another more familiar example happens anytime that you are traveling in a car:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in a car moving at a constant speed (let's say 55 MPH) you are moving at the same speed along with it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the brakes of the car are engaged, they slow the car down but your inertia tends to keep you moving in the direction that the car was going.  This will be more noticeable as the brakes are applied harder and harder because the deceleration of the car is more extreme.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice this as pressure against the seat belt as the car holds you in place.  You are still moving forward, but you are getting slower (decelerating).  In an airplane the exact same thing is happening only it is in a vertical direction instead of a horizontal direction like in the car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you are feeling is your stomach floating up a little inside your body, because while the seat belt is holding you down, it doesn't hold your stomach in place!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-26T21:58:37.947" LastActivityDate="2014-03-26T21:58:37.947" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2673" PostTypeId="2" ParentId="2664" CreationDate="2014-03-25T03:10:42.780" Score="9" Body="&lt;p&gt;There are &lt;a href=&quot;https://www.google.com/search?q=bluetooth%20aviation%20headset&amp;amp;oq=bluetooth%20aviation%20&amp;amp;aqs=chrome.1.69i57j0l2j69i60j0l2.6670j0j7&amp;amp;sourceid=chrome&amp;amp;espv=210&amp;amp;es_sm=91&amp;amp;ie=UTF-8&quot;&gt;multiple aviation headsets&lt;/a&gt; approved by the FAA that have built-in Bluetooth.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on that, I'm going to say that this has been tested and will not interfere with the aircraft avionics.  Radio/EMI testing is part of the testing that any device approved by the FAA for use in an airplane must go through.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="64" LastEditDate="2014-03-25T04:41:53.313" LastActivityDate="2014-03-25T04:41:53.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2674" PostTypeId="1" CreationDate="2014-03-25T05:47:46.523" Score="17" ViewCount="5230" Body="&lt;p&gt;Why does the Beech Staggerwing have its low wing in ahead of the high wing? What are the aerodynamic ideas behind this? Other biplanes of the era had the opposite, low wing behind the high one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xkHg4.jpg&quot; alt=&quot;Beech staggerwing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-03-25T11:12:06.527" LastActivityDate="2018-03-05T06:15:14.967" Title="Why does the Beech Staggerwing have its low wing ahead of the high wing?" Tags="&lt;wing&gt;&lt;biplane&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2675" PostTypeId="2" ParentId="2655" CreationDate="2014-03-25T07:45:56.537" Score="5" Body="&lt;p&gt;To answer this question, you need to understand how GPS works. GPS satellites just keep continuously beaming the time the message was transmitter, and the position of the satellite at the time of the transmission. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS receiver/client then interprets your location based on the transit time of each message and computes the distance to each satellite. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means, the satellites or anyone other than your GPS receiver don't know your location. To transmit your location to anyone, you need a medium (such as the internet or GSM network), which is absent at the bottom of the ocean. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Global_Positioning_System#Basic_concept_of_GPS&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1770" LastEditorUserId="946" LastEditDate="2014-03-26T01:03:07.907" LastActivityDate="2014-03-26T01:03:07.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2676" PostTypeId="1" AcceptedAnswerId="2679" CreationDate="2014-03-25T09:29:15.277" Score="10" ViewCount="902" Body="&lt;p&gt;Does &lt;em&gt;CFIT&lt;/em&gt; apply in case of a plane (not an seaplane) failing a &quot;landing&quot; emergency in the open sea?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="22550" LastEditDate="2018-12-20T03:19:44.400" LastActivityDate="2020-07-02T11:59:26.847" Title="Is a failed ditching of an aircraft also Controlled Flight Into Terrain (CFIT)?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;accidents&gt;&lt;ditching&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2678" PostTypeId="2" ParentId="2466" CreationDate="2014-03-25T10:47:13.453" Score="3" Body="&lt;p&gt;The earlier report referred to in the question has been contradicted by a later report. This undermines the premise of the question. Currently (24/3/2014) it appears there is no evidence that any change in flight-path was entered into the flight management system.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Malaysian officials, in a written update Sunday on the search, cast doubt on the theory that someone, perhaps a pilot, had reprogrammed the aircraft to make an unexpected left turn during the flight.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;The last ACARS transmission, sent at 1:07 a.m., showed nothing unusual. The 1:07 a.m. transmission showed a normal routing all the way to Beijing,&amp;quot; it read.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://edition.cnn.com/2014/03/23/world/asia/malaysia-airlines-plane/index.html?iid=article_sidebar&quot; rel=&quot;nofollow noreferrer&quot;&gt;CNN&lt;/a&gt; March 24, 2014 at 0225 GMT&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-25T10:47:13.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2679" PostTypeId="2" ParentId="2676" CreationDate="2014-03-25T11:06:36.320" Score="14" Body="&lt;p&gt;Boeing &lt;a href=&quot;http://web.archive.org/web/20110629092157/http://www.boeing.com/commercial/safety/manufacturers_role.html#controlledFlight&quot;&gt;defines&lt;/a&gt; it in the following way:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Controlled flight into terrain (CFIT) describes an accident in which a&#xA;  flight crew &lt;strong&gt;unintentionally&lt;/strong&gt; flies an airplane into the ground, a&#xA;  mountain, water or an obstacle. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since it's not unintentional, it's better described as forced landing or in your case, ditching.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-03-25T11:06:36.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2680" PostTypeId="2" ParentId="2674" CreationDate="2014-03-25T11:10:33.353" Score="13" Body="&lt;p&gt;Wikipedia (certainly not a proper source) suggests:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Model 17's unusual negative stagger wing configuration (the upper&#xA;  wing staggered behind the lower) and unique shape &lt;strong&gt;maximized pilot&#xA;  visibility while negligibly reducing interference between the wings&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which itself is sourced from &quot;The Beechcraft Biplanes&quot;. Sport Avaition. January 1961.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally as you state the choice is for the lower wing to be further back due to the negative pressure on top which you do not want interfering and reducing the effectiveness of the upper wing.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-25T11:18:30.250" LastActivityDate="2014-03-25T11:18:30.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2681" PostTypeId="2" ParentId="2671" CreationDate="2014-03-25T11:14:39.893" Score="3" Body="&lt;p&gt;Once in the climb, the flaps are retracted from the take off setting, the rate of climb reduces, then slowly increases again as the reduced drag allows the plane to go faster.&lt;/p&gt;&#xA;" OwnerUserId="1777" LastActivityDate="2014-03-25T11:14:39.893" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2682" PostTypeId="2" ParentId="2623" CreationDate="2014-03-25T11:53:00.630" Score="1" Body="&lt;p&gt;The plane wasn't flying along that arc. At the moment in time that the ping was evaluated, the plane had to be somewhere on that arc. They never said it maintained an equidistance from the satellite. That would be bizarre.&lt;/p&gt;&#xA;" OwnerUserId="1779" LastEditorUserId="97" LastEditDate="2014-03-25T12:54:33.090" LastActivityDate="2014-03-25T12:54:33.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2683" PostTypeId="2" ParentId="2581" CreationDate="2014-03-25T12:16:21.220" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.bournemouthecho.co.uk/news/10878747.Axed_Palmair_jet_makes_its_final_landing_at_aviation_museum/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bournemouth aviation museum?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;BOURNEMOUTH’S popular aviation museum has a new addition – of a more recent vintage.&lt;/p&gt;&#xA;&lt;p&gt;The distinctive exhibit is an old Palmair jet, a familiar sight at the airport until the carrier closed three years ago.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;strong&gt;Boeing 737-200&lt;/strong&gt; carried tens of thousands of holidaymakers from Bournemouth Airport, before being replaced by a more modern plane.&lt;/p&gt;&#xA;&lt;p&gt;The front half of the white fuselage was unveiled at the museum along Parley Lane last week.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviation-museum.co.uk/index.php?id=43&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6JHKh.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-25T12:16:21.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2684" PostTypeId="2" ParentId="2581" CreationDate="2014-03-25T12:44:51.900" Score="1" Body="&lt;p&gt;This is a little bit of an &quot;outside of the box&quot; answer, and I won't be accepting it. I'm just sharing it so there are more ideas of places to do this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.virginexperiencedays.co.uk/boeing-737-flight-simulator-15-minute-flight-sp8&quot; rel=&quot;nofollow&quot;&gt;Virgin Experience Days&lt;/a&gt; offer 15 minutes of 737 simulator time to newbies for £24.50 in London. I guess I could just tell them I don't want to fly, I just want to &quot;play with the buttons&quot; :P&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-03-25T12:44:51.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2685" PostTypeId="1" AcceptedAnswerId="2707" CreationDate="2014-03-25T13:11:58.463" Score="37" ViewCount="15024" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2532/could-malaysia-airlines-flight-370-have-sunk-without-leaving-any-floating-wrecka/2612#comment4993_2612&quot;&gt;A comment&lt;/a&gt; by @AsheeshR says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Hudson River Landing was due to a combination of piloting skill and an autopilot system that was engaged right till impact and kept the plane in a controlled descent within a safe flight envelope.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It was an Airbus aircraft, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/149/what-are-the-main-differences-between-boeing-and-airbus-aircraft&quot;&gt;the autopilot has priority over pilot input&lt;/a&gt;, but how exactly did the autopilot play a role in getting them down safely?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exact procedures did Sully and the crew follow when landing? Was there anything in addition to standard ditching procedures, that might have contributed to them landing in one piece?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ju8ql.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-02-03T13:51:04.447" Title="How, exactly, did US1549 land on the Hudson?" Tags="&lt;landing&gt;&lt;accidents&gt;&lt;autopilot&gt;&lt;ditching&gt;&lt;us1549-accident&gt;" AnswerCount="3" CommentCount="16" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2686" PostTypeId="5" CreationDate="2014-03-25T13:17:19.523" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Water_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ditching&lt;/a&gt; is another term for an emergency landing on water, by an aircraft that isn't designed for water landings. &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow noreferrer&quot;&gt;US Airways 1549&lt;/a&gt; is a very well-known (and successful) ditching.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about ditching procedures, training, regulations etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Water landings by aircraft that &lt;em&gt;are&lt;/em&gt; designed to do so are not considered ditchings; use the &lt;a href=&quot;/questions/tagged/seaplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;seaplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;seaplane&lt;/a&gt; tag for these instead.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-04-05T10:07:30.200" LastActivityDate="2019-04-05T10:07:30.200" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2687" PostTypeId="4" CreationDate="2014-03-25T13:17:19.523" Score="0" Body="Use this tag for questions about emergency landings in water, in aircraft not designed for water landings. For emergency landings on land, use the &quot;landing&quot; and &quot;emergency&quot; tags instead." OwnerUserId="97" LastEditorUserId="62" LastEditDate="2016-12-07T20:01:07.090" LastActivityDate="2016-12-07T20:01:07.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2688" PostTypeId="5" CreationDate="2014-03-25T13:19:39.807" Score="0" Body="&lt;p&gt;A &lt;em&gt;flight data recorder&lt;/em&gt; (FDR) is one of two major types of &lt;a href=&quot;/questions/tagged/flight-recorders&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-recorders&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-recorders&lt;/a&gt; (popularly, though inaccurately, known as &quot;black boxes&quot;; the flight recorders are actually bright orange, to make them easier to find following a crash), used to record aircraft parametric data for &lt;a href=&quot;/questions/tagged/accident-investigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;accident-investigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;accident-investigation&lt;/a&gt; purposes; the other flight recorder is the &lt;a href=&quot;/questions/tagged/cockpit-voice-recorder&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cockpit-voice-recorder&amp;#39;&quot; rel=&quot;tag&quot;&gt;cockpit-voice-recorder&lt;/a&gt;, which records cockpit audio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first FDRs were developed during World War II, and were used to record data during &lt;a href=&quot;/questions/tagged/flight-testing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-testing&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-testing&lt;/a&gt;; FDRs became available for &lt;a href=&quot;/questions/tagged/airliner&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airliner&amp;#39;&quot; rel=&quot;tag&quot;&gt;airliner&lt;/a&gt;s in the 1950s, and were made mandatory for large airliners in most countries (starting with &lt;a href=&quot;/questions/tagged/australia&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;australia&amp;#39;&quot; rel=&quot;tag&quot;&gt;australia&lt;/a&gt;) in the 1960s, following a number of crashes where the lack of flight recorders significantly hampered the investigation process.  For several decades, most FDRs recorded only five parameters - &lt;a href=&quot;/questions/tagged/altitude&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;altitude&amp;#39;&quot; rel=&quot;tag&quot;&gt;altitude&lt;/a&gt;, indicated &lt;a href=&quot;/questions/tagged/airspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspeed&lt;/a&gt;, magnetic &lt;a href=&quot;/questions/tagged/heading&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;heading&amp;#39;&quot; rel=&quot;tag&quot;&gt;heading&lt;/a&gt;, vertical acceleration, and microphone keying (to allow the FDR recording to be synchronised with the CVR recording) - plus a time signal.  However, beginning in the 1970s and 1980s, manufacturers started to include more and more parameters in FDR recordings, and governmental &lt;a href=&quot;/questions/tagged/regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;regulations&lt;/a&gt; were updated to require more and more of these additional parameters in addition to the basic five.  As an example, current &lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt; require FDRs to record 88 different parameters, and the FDRs on most newer aircraft go far beyond this, recording hundreds or even thousands of parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some newer recorders store both parametric and audio data in a single memory module (but still have two separate recorders); this provides redundancy, as, even if one recorder is lost or destroyed, all audio and parametric data can still be recovered from the other recorder.  Such a combined FDR/CVR is known as a &lt;em&gt;cockpit voice and data recorder&lt;/em&gt;, or CVDR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been five main types of FDR over the years, distinguished by the medium used to record the data:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The first FDRs used photographic film, which could be easily read but was fragile and single-use-only; this limited their use to test flights and other one-off applications.&lt;/li&gt;&#xA;&lt;li&gt;Some early commercial FDRs recorded data on magnetic wire, which was much more durable and could be reused, but never became very popular due to the difficulty in working with it.&lt;/li&gt;&#xA;&lt;li&gt;The first FDR technology to become widely successful used movable styli to etch data traces into a long strip of heat-resistant metal foil; this was the gold standard for FDRs for decades, due to its durability and ability to record data from large numbers of flights before needing replacement, but eventually fell out of use due to only a small number of parameter traces fitting on the strip of foil.&lt;/li&gt;&#xA;&lt;li&gt;Later FDRs used magnetic tape, which supported larger numbers of parameters and could be reused indefinitely, but had the disadvantages of a shorter recording time and being bulky and relatively fragile.&lt;/li&gt;&#xA;&lt;li&gt;FDRs using solid-state flash memory first became available in 1990, and are now used in almost all new installations; these recorders can store an enormous amount of data in a very small memory chip, allowing this &quot;memory module&quot; to be made smaller and lighter and have more layers of shielding around it, and yet still store data from hundreds to thousands of parameters over hundreds of flights.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information about flight data recorders, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_recorder#Flight_data_recorder&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-09-06T06:09:45.980" LastActivityDate="2019-09-06T06:09:45.980" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2689" PostTypeId="4" CreationDate="2014-03-25T13:19:39.807" Score="0" Body="A flight data recorder, or FDR, is one of two flight recorders (&quot;black boxes&quot;), used to record pilot input and aircraft parameters for the purpose of investigation of accidents and incidents." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-03-31T01:17:52.503" LastActivityDate="2019-03-31T01:17:52.503" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2690" PostTypeId="5" CreationDate="2014-03-25T13:20:56.383" Score="0" Body="&lt;p&gt;The cockpit of an aircraft contains flight instruments on an instrument panel, and the controls that enable the pilot to fly the aircraft. In most airliners, a door separates the cockpit from the passenger compartment.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cockpit&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T14:58:15.140" LastActivityDate="2014-03-25T14:58:15.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2691" PostTypeId="4" CreationDate="2014-03-25T13:20:56.383" Score="0" Body="A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T14:58:21.573" LastActivityDate="2014-03-25T14:58:21.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2692" PostTypeId="5" CreationDate="2014-03-25T13:22:10.640" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-25T13:22:10.640" LastActivityDate="2014-03-25T13:22:10.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2693" PostTypeId="4" CreationDate="2014-03-25T13:22:10.640" Score="0" Body="Commercial aviation is the part of civil aviation, whether general aviation, non-scheduled service, or scheduled airline service, that involves operating aircraft for hire to transport passengers or cargo." OwnerUserId="97" LastEditorUserId="12720" LastEditDate="2016-02-08T14:10:13.087" LastActivityDate="2016-02-08T14:10:13.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2695" PostTypeId="1" AcceptedAnswerId="2697" CreationDate="2014-03-25T13:52:29.940" Score="14" ViewCount="1767" Body="&lt;p&gt;I'm just curious as to what the noises are that you can hear as a passenger in the cabin of an airliner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example (ignore the crew talking), the noise at 7:09 - 7:30 on &lt;a href=&quot;http://youtu.be/44wN01XCUhc?t=7m7s&quot;&gt;this video&lt;/a&gt;; is that the flaps?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What other sounds might a passenger be able to spot?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-04-15T17:53:55.700" Title="What noises can you hear as a passenger?" Tags="&lt;passenger&gt;&lt;airliner&gt;&lt;noise&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2696" PostTypeId="2" ParentId="149" CreationDate="2014-03-25T13:53:36.873" Score="6" Body="&lt;p&gt;My 2 cents:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few things mentioned &lt;a href=&quot;http://www.usatoday.com/story/travel/columnist/cox/2014/03/16/boeing-737-airbus-a320/6380793/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The sidestick and autothrust systems of the Airbus are different than    the conventional yoke  and autothrottle system on the Boeing.&lt;/li&gt;&#xA;  &lt;li&gt;The Airbus technology and quiet cruise was great; the Boeing's    tactile feel  and crosswind capabilities were very good.&lt;/li&gt;&#xA;  &lt;li&gt;There is a difference in the length of the fuselage, making taxiing    different. The handling characteristics in flight are very similar.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-03-25T13:53:36.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2697" PostTypeId="2" ParentId="2695" CreationDate="2014-03-25T14:05:14.440" Score="9" Body="&lt;p&gt;At that point it was indeed the flaps extending in preparation of takeoff (you can see them moving through the rain).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would typically also be able to hear the cargo doors closing (before the plane starts taxiing) and the engines ramping up as you start to take off (&lt;a href=&quot;http://youtu.be/44wN01XCUhc?t=8m53s&quot;&gt;at 8:54&lt;/a&gt; in the same video).&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="97" LastEditDate="2014-03-25T14:08:09.673" LastActivityDate="2014-03-25T14:08:09.673" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2698" PostTypeId="2" ParentId="149" CreationDate="2014-03-25T14:23:17.113" Score="50" Body="&lt;p&gt;On a pilot-vs-FBW system perspective, as mentioned in the comments to the question, the most notable difference is the authority priority:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Boeing trusts more the pilots: they can supersede the Fly-by-wire automatic commands by exerting enough force on the controls&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airbus trusts more the FBW system: if the system is fully functional (&quot;Normal law&quot;) it will always have priority over the pilots to protect the aircraft and keep it in the envelope, but they still have room for &quot;non-standard&quot; maneuvers, e.g. commanding bank angles between 33° and 60°. The autopilot can be activated and de-activated at will by the pilots, and it sits on top of the FBW envelope protection.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One of the most famous examples where this comparison emerges (and the subsequent debate about which approach is better) is the &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot; rel=&quot;noreferrer&quot;&gt;China Airlines 006&lt;/a&gt; accident.&#xA;I won't go into detail, there is the &lt;a href=&quot;https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR8603.pdf&quot; rel=&quot;noreferrer&quot;&gt;accident report&lt;/a&gt; that will provide much more information that I can remember, but suffice to say that this 747 was recovered from a quite unusual attitude&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Jef6s.jpg&quot; alt=&quot;China Airlines 006 attitude history&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in the wiki article, the report states that the passengers were subject up to 5 gs during the maneuver and the stress on the horizontal tail surface has been so great that as a result it was damaged:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wXm0h.jpg&quot; alt=&quot;China Airlines 006 tail damage&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual argumentation goes along the lines that, would this had been an Airbus, the pilots would not have been able to save the aircraft.&#xA;See for example &lt;a href=&quot;http://repository.tudelft.nl/assets/uuid:22554e85-9506-4410-9fb3-9ad6af4b2c8d/W._Falkena_-_PhD_Thesis.pdf&quot; rel=&quot;noreferrer&quot;&gt;this PhD thesis&lt;/a&gt; at page 184 of the pdf, section 6.2.3 &quot;Pilot Authority at the Boundary&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is likely that if the aircraft had prevented the crew from initiating control commands that would lead to aircraft damage, the aircraft (and passengers) would have been lost.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The problem with such a comparison? It focuses on the recovery after the unusual attitude was achieved and totally forgets about the sequence of events that lead to it or, to the very least, assumes that an Airbus would have responded in the same way to the preceding events (then why make a comparison at all?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An honest comparison would take into account this and acknowledge that an Airbus in Normal Law would not enter a spiral dive in the first place, even with an engine out, as bank protection/attitude-hold would prevent it.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="40158" LastEditDate="2019-05-02T06:35:04.343" LastActivityDate="2019-05-02T06:35:04.343" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="2699" PostTypeId="1" AcceptedAnswerId="2825" CreationDate="2014-03-25T14:26:03.227" Score="18" ViewCount="20073" Body="&lt;p&gt;I've noticed that on some airlines (I may have seen it on SAS) the cabin crew had a small touchscreen at the front of the plane which they were using to select recorded audio messages etc, in both their language, and English.&lt;/p&gt;&#xA;&lt;p&gt;Searching the internet, I found out it's called a Flight Attendant Panel — here are &lt;a href=&quot;http://boardingarea.com/aadvantagegeek/2013/01/28/a-field-trip-to-see-the-new-american-airlines-livery/&quot; rel=&quot;noreferrer&quot;&gt;some photos&lt;/a&gt; I found:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nveae.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tqm8Y.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;So I gather they can control the lighting, and movies; but &lt;strong&gt;what else can these panels do?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;I also found &lt;a href=&quot;http://www.ecafaros.com/en/simulator/flight-simulators-flight-simulators-fap-trainer--flight-attendant-panel-trainer-%28fap%29-/66.htm&quot; rel=&quot;noreferrer&quot;&gt;a FAP trainer&lt;/a&gt;, which says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This virtual training environment generates a realistic FAP representation including OBRM, CAM and PRAM&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PxXGW.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;What are OBRM, CAM and PRAM? What is being displayed above?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-04-07T18:42:39.580" Title="What can the Flight Attendant Panel do?" Tags="&lt;crew&gt;&lt;aircraft-systems&gt;&lt;flight-attendant&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2700" PostTypeId="5" CreationDate="2014-03-25T14:28:49.793" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-25T14:28:49.793" LastActivityDate="2014-03-25T14:28:49.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2701" PostTypeId="4" CreationDate="2014-03-25T14:28:49.793" Score="0" Body="The Flight Attendant Panel allows the cabin crew to control aspects of the cabin, such as lighting." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T15:25:19.683" LastActivityDate="2014-03-25T15:25:19.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2702" PostTypeId="1" AcceptedAnswerId="2704" CreationDate="2014-03-25T14:32:25.453" Score="37" ViewCount="39758" Body="&lt;p&gt;What is a &lt;strong&gt;Flight Director&lt;/strong&gt;, and how does it differ from &lt;strong&gt;Autopilot&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="64" LastEditDate="2014-03-25T15:27:36.310" LastActivityDate="2016-10-26T00:35:35.893" Title="What is a &quot;Flight Director&quot;?" Tags="&lt;autopilot&gt;&lt;aircraft-systems&gt;&lt;flight-director&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2703" PostTypeId="2" ParentId="2685" CreationDate="2014-03-25T14:37:45.957" Score="1" Body="&lt;p&gt;There is not much training for situations like that because they are very rare and the simulators cannot teach accurately what to expect when a plane touches down on water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain in this situation got almost everything right for a water landing, as he kept the nose up and wings level, he let the tail hit the water first slowing the plane down enough so it survived the impact. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure autopilot played much role in this if any, because there was no runway length and reverse thrust to concider.  &lt;/p&gt;&#xA;" OwnerUserId="1732" LastActivityDate="2014-03-25T14:37:45.957" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2704" PostTypeId="2" ParentId="2702" CreationDate="2014-03-25T14:42:52.780" Score="34" Body="&lt;p&gt;The flight director is related to the autopilot system. It displays a guide on the artificial horizon, which shows the attitude of the airplane, but does nothing to control the plane. The guide represents a reference of an airplane attitude that will follow the parameters set for the autopilot. The pilot can manually fly the plane directly where the flight director indicates, and by doing so the plane will follow the parameters set for the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is engaged, autopilot flies the plane to follow the flight director. The flight director serves as a visual indication of where the autopilot wants the plane to go. Although a flight director typically accompanies an autopilot system, some aircraft have a flight director without an autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The procedure to engage them is to first turn on the flight director, which will show where the autopilot wants the plane to be, and then to engage the autopilot, which will then automatically fly the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what the autopilot controls can look like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6j0Ix.gif&quot; alt=&quot;Autopilot controls&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the Boeing flight director, visible as the crossed magenta lines in the center of the screen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BOJuv.png&quot; alt=&quot;Flight Director&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-07-29T15:41:24.290" LastActivityDate="2014-07-29T15:41:24.290" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2705" PostTypeId="2" ParentId="786" CreationDate="2014-03-25T15:04:33.813" Score="0" Body="&lt;p&gt;Apart from the actual physical feasibility discussed in other answers the main risk is a stall situation during the turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winch-launching of gliders is a situation where &quot;power loss&quot; in form of a rope-break is quite common and the reaction to this situation is one of the most importand drills during your training. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from the initial speed and AoA recovery, the decision to turn or not is rather crucial, but when turning you have to take utter care of your speed to avoid stalling. This may be even worse for motor pilots, because you might want to keep banking with a &quot;normal&quot; horizon reference as usual, which can be a bad idea if you are lacking the necessary power to sustain that.&lt;/p&gt;&#xA;" OwnerUserId="95" LastActivityDate="2014-03-25T15:04:33.813" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2706" PostTypeId="2" ParentId="2702" CreationDate="2014-03-25T15:29:50.410" Score="11" Body="&lt;p&gt;It lets the pilot know what the autopilot would do if it were flying instead, by displaying an indicator, usually a miniature pink plane or line, on the artificial horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between the autopilot and flight director is that the autopilot flies the plane, the flight director gives the pilot an idea of what the autopilot would like to do if it was in charge.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-03-25T15:29:50.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2707" PostTypeId="2" ParentId="2685" CreationDate="2014-03-25T15:43:01.710" Score="33" Body="&lt;p&gt;The &lt;a href=&quot;http://www.ntsb.gov/investigations/summary/AAR1003.html&quot; rel=&quot;noreferrer&quot;&gt;NTSB report&lt;/a&gt; is a great resource when looking for information about an incident like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an Engine Dual Failure Checklist discussed starting in section 1.17.1.2 of the report. This includes steps to attempt restarting the engines, and further steps depending on whether or not the engines can be started, and finally steps to help prepare for a forced landing. Pilots train on engine failures regularly, so they are already familiar with the procedures. The report discusses how their actions compared to what the checklists say. Since the incident occurred at such a low altitude right after takeoff, they didn't have time to complete all of the steps. They did what they had time for, and had to make quick decisions about what their options were.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report also discusses in section 1.17.3.2 the ditching training the pilots received. There was guidance in the manual, but no specific scenarios included in their simulator training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The autopilot is great for use in normal situations. However, as soon as anything is going wrong, the pilot should take control of the plane. You do not want to take time to figure out &quot;what's it doing now&quot; in a difficult situation. So in this situation, the autopilot probably disconnected when the engines went out, or was manually disconnected by the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 1.6.3 talks about the flight envelope protections. I believe these protections are what you are referring to when you say that the autopilot has more control. They are designed to protect the plane from stalling or otherwise exiting controlled flight. Because the pilot was able to start the APU to provide electrical power, the plane remained in the &quot;normal law&quot; mode where these protections were available. This limits the control the pilot has in order to protect the plane, in the sense that the plane will override pilot inputs to avoid dangerous situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 2.7.2 discusses the impact of these protections in this case.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane’s airspeed in the last 150 feet of the descent was low&#xA;  enough to activate the alpha-protection mode of the airplane’s&#xA;  fly-by-wire envelope protection features...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Because of these features, the airplane could not reach the maximum&#xA;  AOA attainable in pitch normal law for the airplane weight and&#xA;  configuration; however, the airplane did provide maximum performance&#xA;  for the weight and configuration at that time...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The flight envelope protections allowed the captain to pull full aft&#xA;  on the sidestick without the risk of stalling the airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An interesting point in the report is that Airbus certified the plane to be able to land on the water intact under certain conditions. Here is how the actual conditions compared to the certified conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 1.6.7&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KQt7J.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report mentions that it would be extremely difficult to meet all of these requirements in an airplane with no power. The values that are higher, notably the mass and descent rate, are factors in the damage the airplane received.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-03-30T16:30:19.400" LastActivityDate="2014-03-30T16:30:19.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2708" PostTypeId="2" ParentId="2695" CreationDate="2014-03-25T17:18:06.187" Score="10" Body="&lt;p&gt;There are loads of noises you might hear; there are fuel pumps, hydraulic pumps, air circulation, adjustment screws, servos, and on Airbus aircraft a strange clanking noise when you go over bumps in the tarmac.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground you may hear (and feel) cargo pallets rolling on the hold, and the hold doors being opened and shut. In-flight you have engine noises and air flow noises.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="97" LastEditDate="2014-04-03T04:17:39.360" LastActivityDate="2014-04-03T04:17:39.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2709" PostTypeId="2" ParentId="2676" CreationDate="2014-03-25T17:22:25.703" Score="11" Body="&lt;p&gt;Controlled flight into terrain means that the aircraft is under positive control, that is it's within its flight envelope and is being actively managed, however it's course brings it unintentionally into contact with terrain. A aircraft flying into the side of a mountain is controlled flight into terrain. An aircraft ditching, successful or not, is an intentional action so doesn't qualify. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-03-25T17:22:25.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2710" PostTypeId="2" ParentId="2644" CreationDate="2014-03-25T17:38:39.040" Score="8" Body="&lt;p&gt;You're right that two airports can share the same 3-letter code, but they're not necessarily IATA codes (they could actually be &lt;a href=&quot;https://en.wikipedia.org/wiki/Location_identifier#FAA_identifier&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA identifiers&lt;/a&gt;, or just locally assigned codes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In implementing &lt;a href=&quot;https://aviation.stackexchange.com/users/322/otto-the-autopilot&quot;&gt;Otto the Autopilot&lt;/a&gt; in &lt;a href=&quot;http://chat.stackexchange.com/rooms/12036/the-hangar&quot;&gt;our chat room&lt;/a&gt;, for commands like &lt;code&gt;!!weather JFK&lt;/code&gt;, I needed to find a way to reliably convert IATA codes to ICAO codes. I ended up using the same source as you linked to, and imported the columns we needed into MySQL. A quick query shows 65 (i.e. &gt;=130) duplicates:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;AHT AJL API APS ARS AUS BJW CGY CLG CPO CSZ DDU DZN GIG HKG HYD IOR ISG IZA JFR JRS KFE KMM&#xA;KWB KYF LIM LUZ MCJ MCU MJF MNI MPD MPT MRE MUC NST NWT OBI OHE PCO PDG PHG PIV PPJ PRI PRM&#xA;PSV RCH REQ RZS SEA SFK STI SYC SZR TFY THO TNO TPJ UCN ULG VME VQS WRW YDT&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The problem is, that IATA &lt;a href=&quot;http://www.iata.org/publications/Pages/coding.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;wants you to pay&lt;/a&gt; several thousand dollars for access to their list. So OurAirports attempts to collect all the known IATA codes, but it &lt;em&gt;is&lt;/em&gt; user-editable, like Wikipedia. So there are inaccuracies in their database; and as I mentioned, there is some overlap between IATA/FAA/local.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual IATA codes &lt;a href=&quot;https://en.wikipedia.org/wiki/IATA_code&quot; rel=&quot;nofollow noreferrer&quot;&gt;are unique&lt;/a&gt; (although &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Air_Transport_Association_airport_code&quot; rel=&quot;nofollow noreferrer&quot;&gt;sometimes reused&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-03-26T13:26:08.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2712" PostTypeId="5" CreationDate="2014-03-25T18:27:16.487" Score="0" Body="&lt;p&gt;Aerobatic maneuvers are flight paths putting aircraft in unusual attitudes, in air shows, dog fights or competition aerobatics. Aerobatics can be performed by a single aircraft or in formation with several others. Nearly all aircraft are capable of performing aerobatics maneuvers of some kind, although it may not be legal or safe to do so in certain aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wikipedia: &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerobatics&quot; rel=&quot;nofollow&quot;&gt;Aerobatics&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerobatic_maneuver&quot; rel=&quot;nofollow&quot;&gt;Aerobatic Maneuver&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T19:18:44.527" LastActivityDate="2014-03-25T19:18:44.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2713" PostTypeId="4" CreationDate="2014-03-25T18:27:16.487" Score="0" Body="The practice of flying maneuvers involving aircraft attitudes that are not used in normal flight, e.g. a barrel roll." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T19:18:54.167" LastActivityDate="2014-03-25T19:18:54.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2714" PostTypeId="5" CreationDate="2014-03-25T18:29:23.320" Score="0" Body="&lt;p&gt;Airspeed is the relative speed of an aircraft through an air mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The measurement and indication of airspeed is ordinarily accomplished on board an aircraft by an airspeed indicator (&quot;ASI&quot;) connected to a pitot-static system. The pitot-static system comprises one or more pitot probes (or tubes) facing the on-coming air flow to measure pitot pressure (also called stagnation, total or ram pressure) and one or more static ports to measure the static pressure in the air flow. These two pressures are compared by the airspeed indicator to give an &lt;em&gt;indicated airspeed&lt;/em&gt; reading.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airspeed&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="64" LastEditDate="2014-03-25T18:49:06.817" LastActivityDate="2014-03-25T18:49:06.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2715" PostTypeId="4" CreationDate="2014-03-25T18:29:23.320" Score="0" Body="The speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed (&quot;IAS&quot;), calibrated airspeed (&quot;CAS&quot;), true airspeed (&quot;TAS&quot;), equivalent airspeed (&quot;EAS&quot;) and density airspeed." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-03-25T18:49:11.830" LastActivityDate="2014-03-25T18:49:11.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2716" PostTypeId="5" CreationDate="2014-03-25T18:30:27.110" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-03-25T18:30:27.110" LastActivityDate="2014-03-25T18:30:27.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2717" PostTypeId="4" CreationDate="2014-03-25T18:30:27.110" Score="0" Body="For questions that deal with aviation aspects of U.S. Customs and Border Protection" OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2016-07-08T14:33:44.697" LastActivityDate="2016-07-08T14:33:44.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2718" PostTypeId="1" CreationDate="2014-03-25T18:57:18.167" Score="5" ViewCount="116" Body="&lt;p&gt;I thought the shape of the wing gave an airplane upward lift. How can it fly if it's upside down?&lt;/p&gt;&#xA;" OwnerUserId="1796" LastActivityDate="2014-03-25T18:57:18.167" Title="How can an airplane fly upside down?" Tags="&lt;aerodynamics&gt;&lt;aerobatics&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2014-03-25T19:23:18.090" ContentLicense="CC BY-SA 3.0" />
  <row Id="2719" PostTypeId="2" ParentId="2655" CreationDate="2014-03-25T18:59:42.770" Score="2" Body="&lt;p&gt;Completely agree with Thilak. &#xA;With a GPS receiver attached to a black box, only the black box will be able to know its own location. We are able to use GPS for tracking assets becuase those devices transmit the location information received from GPS, using various channels such as GPRS or satellite connectivity. In the case of black box - &#xA;(a) GPS signals from satellites reaching the receiver is not guaranteed at all places e.g ocean beds.&#xA;(b) If the black box did had the channel to transmit GPS information (Which it does not have) to back office, it could rather send much more actual data. &lt;/p&gt;&#xA;" OwnerUserId="1795" LastActivityDate="2014-03-25T18:59:42.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2720" PostTypeId="1" AcceptedAnswerId="2722" CreationDate="2014-03-25T19:05:37.467" Score="59" ViewCount="24265" Body="&lt;p&gt;What are these things hanging off the trailing edge of the wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen them in almost all of the aircraft I've flown in, and can't remember if they're exclusively Boeing or Airbus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/Q4JjQha.jpg&quot; alt=&quot;wing trailing edge&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1796" LastEditorUserId="3386" LastEditDate="2018-07-18T13:58:03.183" LastActivityDate="2018-12-29T18:46:52.723" Title="What are these things hanging off the trailing edge of the wing?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;feature-identification&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2721" PostTypeId="2" ParentId="2720" CreationDate="2014-03-25T19:23:59.043" Score="27" Body="&lt;p&gt;These are &lt;a href=&quot;https://en.wikipedia.org/wiki/Static_discharger&quot;&gt;&lt;strong&gt;static wicks&lt;/strong&gt;&lt;/a&gt; or static dischargers.  They dissipate static electrical buildup caused by the friction of air flowing over the surface of the aircraft.  The air friction tends to separate electrons from their atoms just as rubbing a balloon tends to do, causing an imbalance of electrical charge on a body.  The wicks work by providing a pointed surface where airflow separates from contact with the aircraft body.  The excess charge tends to flow into the air and is swept away from the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="643" LastActivityDate="2014-03-25T19:23:59.043" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2722" PostTypeId="2" ParentId="2720" CreationDate="2014-03-25T19:28:29.840" Score="58" Body="&lt;p&gt;Those are &lt;a href=&quot;http://en.wikipedia.org/wiki/Static_discharger&quot;&gt;static wicks&lt;/a&gt; -- Basically these are little wires screwed to the airframe.&lt;br&gt;&#xA;Their purpose is to discharge the static electricity that an aircraft picks up moving through the air - especially in clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The static discharge tends to happen at &quot;pointy&quot; protrusions from the aircraft - if this happened through antennas it could cause radio and navigation interference, so to prevent that static wicks are installed, providing a low-resistance protrusion for the charge to dissipate through (and as an additional benefit, dissipating the charge helps ensure your aircraft doesn't attract lightning strikes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a couple of closer pictures:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/72OlO.jpg&quot; alt=&quot;Static Wicks installed&quot;&gt; &lt;a href=&quot;https://i.stack.imgur.com/e9i7e.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e9i7em.jpg&quot; alt=&quot;Static Wick close up&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-25T19:28:29.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2723" PostTypeId="1" AcceptedAnswerId="2724" CreationDate="2014-03-25T20:08:36.673" Score="28" ViewCount="41631" Body="&lt;p&gt;Why do they call flight data recorders a &quot;black box&quot; if it's orange in color?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/P7DHp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/P7DHp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just curious about this since I've seen several images of black boxes but they all come in orange colors, and not black.  I can understand orange being used to help brightly identify the box , but then why call it a &quot;black&quot; box?&lt;/p&gt;&#xA;" OwnerUserId="1797" LastEditorUserId="1797" LastEditDate="2016-02-14T03:33:43.330" LastActivityDate="2016-02-14T03:33:43.330" Title="Why are FDR's called &quot;black boxes&quot; when they are actually orange?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2724" PostTypeId="2" ParentId="2723" CreationDate="2014-03-25T20:13:59.953" Score="15" Body="&lt;p&gt;A black box (generally speaking) is a device or box whose internal working are not of as much interest or value but rather the input and output.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_Data_Recorder&quot;&gt;Flight data recorders&lt;/a&gt; are orange so that they can be located easily in case of a crash. If they were black, they can be camouflaged by their surroundings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bright orange color make them stand out easily, because nature didn't make many things orange, besides oranges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is that they are painted/coated with heat-resistant bright orange paint. &lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="64" LastEditDate="2014-03-26T21:08:31.820" LastActivityDate="2014-03-26T21:08:31.820" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2725" PostTypeId="2" ParentId="2723" CreationDate="2014-03-25T20:22:15.123" Score="17" Body="&lt;p&gt;The Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_recorder#History&quot;&gt;Flight recorder&lt;/a&gt; offers a possible explanation for the origin of the term:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... they were essentially photograph-based flight recorders since the record was made on a scrolling photographic film. The latent image was made by a thin ray of light deviated by a mirror tilted according to the magnitude of the data to record (altitude, speed, etc.). Since the inside of the recorder was pitch black, this may be the origin of the &quot;black box&quot; name, often used as a synonym for a flight recorder.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Black_box&quot;&gt;Black box&lt;/a&gt; claims that the term entered the English language around 1945, which is a few years after the first flight data recorder was built.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-25T20:22:15.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2726" PostTypeId="1" AcceptedAnswerId="2743" CreationDate="2014-03-25T21:07:33.480" Score="32" ViewCount="15396" Body="&lt;p&gt;In my experience as a passenger, when the plane stands at the airport and you enter it, the aisle is pretty much horizontal. (Obviously, I've never flown on a DC-3). After takeoff we pitch sharply upwards (duh!), but even after the captain comes on the PA with &quot;we have now reached our cruise altitude&quot;, the aisle continues to point a few degrees upward. Usually it's only at &quot;we're starting our descent into XYZ&quot; that the body returns to a more or less horizontal pitch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? I have some hypotheses, but don't know which, if any, of them hold truth.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It's just how the aerodynamics happen to work out. (Unlikely -- it would seem to be a simple engineering matter to attach the wings to the body at an angle such that the right angle of attack for cruise flight corresponded to the body being horizontal).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pitching the body upwards slightly allows it to generate some lift, free of a proportional increase in drag relative to pushing the cylindrical body straight through the air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passenger jets are deliberately designed such that they never need to pitch lower than horizontal in a routine descent, lest passengers might panic and think they're nosediving to their death. (Also unlikely, unless there is &lt;em&gt;really&lt;/em&gt; no hidden costs in terms of drag, etc.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landings might be more difficult if the plane had to point its nose downwards in order to get closer to the ground -- the nosewheel would hit the runway first. (On the other hand, simply leveling out would count as a flare, so it's not clear to me that's actually a disadvantage).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="959" LastEditorUserId="774" LastEditDate="2014-03-26T03:53:51.263" LastActivityDate="2014-03-27T04:14:12.967" Title="Why do airliners pitch up during cruise?" Tags="&lt;airliner&gt;&lt;cruise&gt;&lt;attitude&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2727" PostTypeId="2" ParentId="2702" CreationDate="2014-03-25T21:11:25.957" Score="5" Body="&lt;p&gt;It's the traditional flight instruments, integrated to work in a complementary way. For example the steering bars moving across the face of the compass so as to give the pilot visual ques for turning onto a desired heading and/or altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight director gives a visual display of the overall aircraft attitude in space. The flight director display reacts to inputs coming from, for example, heading dials, electronic flight plans, and actual aircraft movement. The flight director does not physically control the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The autopilot physically controls the aircraft in response to essentially the same inputs. The flight director essentially does not care if a human or the autopilot is actually in control. The autopilot adds intelligence which allows for various levels of pilot non-intervention up to the point of virtually hands-off control from takeoff to landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Together, the flight director and autopilot permit the pilot to let his skills atrophy while inducing a sense of inferiority on the part of the pilot in command; thus permitting well controlled crashes.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2014-03-25T21:11:25.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2729" PostTypeId="2" ParentId="2726" CreationDate="2014-03-25T21:36:38.150" Score="2" Body="&lt;p&gt;Passenger comfort is a large consideration!  It's simply more comfortable for passengers to be reclined by a degree or two than to sit exactly level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have hopped off a 777 onto a small a/c (if I recall correctly, a Baron of some sort) to island hop and the fuselage was pretty much level.  It certainly felt less comfortable and somehow, even as if it was fighting not to descend.  I would prefer to be a little inclined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that some aircraft cruise slightly nose down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAVEAT.  I am not an expert in physiology or aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comfort is a big factor and the question is not &quot;do airliners fly pitch up&quot; but &quot;why do they?&quot;  That they do is a fact.  I suspect that there are many factors, e.g. the fuselage itself, when pitched up, will generate some lift but ask any experienced flyer about sitting in a rearwards facing seat, or walking towards the front when in a descent which results in a level pitch or pitch down attitude.  It feels less comfortable than when nose up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is level, and you are level, you experience +1g vertically and 0g horizontally. If you recline the seat, you still experience +1 and 0.  If the aircraft is pitch up, you experience a small -ve g component in the horizontal.  Quite what effect this has psychologically, I don't know but it does make a difference.  I've heard, anecdotally, that facing backwards, e.g. in a British Airways biz class seat is less comfortable than in a forward facing one for exactly this reason.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2014-03-26T08:03:03.160" LastActivityDate="2014-03-26T08:03:03.160" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2730" PostTypeId="2" ParentId="2726" CreationDate="2014-03-25T21:46:04.323" Score="8" Body="&lt;p&gt;You need a slight pitch-up attitude to fly: you need a certain angle of attack in order to produce the required lift to remain airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you have imagined, usually the wings are tilted with respect to the fuselage so that in cruise the wings will have the required AoA while the fuselage will be horizontal to minimize drag (and thus fuel consumption).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passenger comfort is much less important than this (and passengers can always lean back their seats).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My hypothesis for your observation is that the &quot;pitch-up&quot; you observe is either a visual/sensory illusion due to the lack of external point of reference (no, the clouds are not a valid reference and the ground is too far away) or you have flown in aircrafts where the floor is not parallel to the aircraft x-y plane.&#xA;Personally, I would lean towards the first hypothesis, as having a non-horizontal floor in flight creates all kind of nuisances to cabin service (again, something you want to avoid).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-03-25T21:46:04.323" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2731" PostTypeId="2" ParentId="2726" CreationDate="2014-03-25T21:54:01.607" Score="12" Body="&lt;p&gt;Ultimately the answer to your question is number (1) from your options above - &lt;em&gt;That's just how the aerodynamics happen to work out&lt;/em&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To generate a certain amount of lift requires that the wing have a specific angle of attack at a given speed. As the wings are more-or-less permanently attached to the fuselage setting the angle of attack requires us to pitch the entire aircraft, changing the deck angle.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is &lt;a href=&quot;http://members.localnet.com/~docsteve/av_files/deck_angle.htm&quot; rel=&quot;noreferrer&quot;&gt;a very nice web page illustrating this in (greatly exaggerated) detail&lt;/a&gt;, so I won't reproduce the full explanation &amp;amp; drawings here.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As to &lt;em&gt;why&lt;/em&gt; the aerodynamics work out that way - that probably has something to do with numbers (3) and (4) - passenger comfort, and ease of executing maneuvers (like landings).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airliners I've been on have a slight nose-up deck angle (maybe 2 degrees) in cruise, which isn't really &quot;noticeable&quot; to most people unless you're carrying a bubble-level or staring very intently at your drink, but the exact angle for climb, cruise, and descent will vary depending on the aircraft and how it's been loaded (you can pretty much descend with any deck angle you like).&lt;br&gt;&#xA;Most people would probably object to flying around with a 10 or 15 degree deck angle (whether nose-up or nose-down), so as a concession to passenger comfort the wings are attached to the fuselage in a way that is aerodynamically favorable (not trying to drag the fat bottom-side of the plane through the sky) and comfortable for the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely most GA aircraft I've been in seem to cruise with a flat or slightly nose-down deck angle, though that could just as easily be an optical illusion from having the big window in front where you can see it. (I'm estimating the deck angle based on the &lt;a href=&quot;https://i.stack.imgur.com/hDwrF.jpg&quot; rel=&quot;noreferrer&quot;&gt;wet compass&lt;/a&gt; tilt since I generally don't serve drinks.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-25T22:07:52.493" LastActivityDate="2014-03-25T22:07:52.493" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2733" PostTypeId="2" ParentId="149" CreationDate="2014-03-25T21:57:07.477" Score="18" Body="&lt;p&gt;Airbus (A320+; A300 and A310 have traditional controls) uses &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_control_modes_(electronic)#Flight_control_laws_.28Airbus.29&quot; rel=&quot;noreferrer&quot;&gt;flight control laws&lt;/a&gt;. In flight, the side-stick input does not indicate desired position of control surfaces, but desired wing loading and roll rate. The flight computer takes care of trimming the aircraft for straight flight at current speed and balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing uses traditional controls, where the position of control column corresponds to position of control surfaces and force on the control column corresponds to force on the control surfaces. This means that the pilot has to adjust the trim manually when not using autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Airbus system is more convenient, but it has its disadvantages. The neutral stability means that the aircraft won't tend to maintain speed by changing pitch, so the pilots have to monitor speed more carefully. It really needs the flight envelope protections to be considered safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has flight envelope protections since 777, so that's not a difference any more. I don't think they are adding them to new versions of 737 though.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2017-09-25T17:06:34.697" LastActivityDate="2017-09-25T17:06:34.697" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2734" PostTypeId="2" ParentId="1630" CreationDate="2014-03-25T21:59:02.697" Score="5" Body="&lt;p&gt;&lt;strong&gt;Standard Rate of Turn for Heavy Aircraft?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standard rate turn is, well, standard. The standard is 3 degrees (of heading change) per second. So a 360 turn takes 2 minutes at the standard turn rate. Didn't say anything about the aircraft ....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every aircraft type has a specific bank angle at which it is turning at the standard rate. It's all due to the design of the aircraft. Further that bank angle yielding a standard rate of turn changes with airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2 minute turn indicator&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Means &quot;line me up and it will take you 2 minutes to do a 360 turn.&quot; This happens to be a standard rate turn, not co-incidentally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4 minute turn indicator&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Means &quot;line me up and it will take you 4 minutes to do a 360 turn.&quot; This just happens to be half standard rate. We know this because it takes 4 minutes for a 360. It make the arithmetic simpler than say, a 7 minute turn indicator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why bother with one of these, never mind 4 vs 2?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compass problems? Roll into a standard rate turn and hack a watch. Now you can time yourself to reasonably accurate heading changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why a 4 instead of a 2?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Allow the aircraft to do a timed turn but with less bank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Huge, lumbering aircraft don't roll so quickly - turn timing is affected. Heavy &amp;amp; huge means for any bank angle it's more of a control issue. And, passenger comfort considerations. &lt;/p&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2014-03-25T21:59:02.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2735" PostTypeId="2" ParentId="2589" CreationDate="2014-03-25T22:10:52.487" Score="1" Body="&lt;p&gt;Mode of air navigation I've witnessed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Celestial - sextant and charts. Like, no kidding, right out of days of sailing ships.&lt;/li&gt;&#xA;&lt;li&gt;Atmospheric pressure - driving along specific barometric pressure lines. By no means a primary form of navigation.&lt;/li&gt;&#xA;&lt;li&gt;Omega - now obsolete. Triangulates on a small number of very powerful radio transmitters spread around the globe. At least good enough to hit the ADIZ w/in limits. I'm told when particularly close to a transmitter it can be as accurate as A Cat 2 ILS beam.&lt;/li&gt;&#xA;&lt;li&gt;Inertial Nav - &lt;/li&gt;&#xA;&lt;li&gt;GPS. what's that?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2014-03-25T22:10:52.487" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2736" PostTypeId="2" ParentId="2723" CreationDate="2014-03-25T22:39:45.697" Score="5" Body="&lt;p&gt;The adjective &quot;black&quot; in &quot;black box&quot; means &quot;opaque&quot;.  Engineering also uses the phrase &quot;black box testing&quot;, which means tests that are done without access to system internals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, &quot;white box&quot; means transparent, in which internal signals may be recorded or manipulated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A black box recorder is presumably recording pilot actions on the system as well as the state shown to the pilot on the instruments, but none of the avionics internal variables.  I doubt any modern FDR would be designed this way, however, since without the internal variables diagnosis of failure could be very difficult.&lt;/p&gt;&#xA;" OwnerUserId="582" LastActivityDate="2014-03-25T22:39:45.697" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2737" PostTypeId="1" AcceptedAnswerId="2833" CreationDate="2014-03-26T02:33:48.287" Score="9" ViewCount="1352" Body="&lt;p&gt;STAR charts often have expected altitudes. For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6219h.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is, of course, different from mandatory crossing altitudes, and it seems a STAR with &lt;em&gt;only&lt;/em&gt; expected altitudes would be insufficient for ATC to issue a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1624/what-is-a-descend-via-clearance&quot;&gt;descend via&lt;/a&gt; clearance, though I could be wrong about the second part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some charts say &quot;VERTICAL NAVIGATION PLANNING INFORMATION&quot; before the expected altitude, so my assumption is that these altitudes are strictly for planning purposes and allow a top of descent to be calculated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When you enter the STAR in the FMS, will it pre-populate the expected altitude, and does this show up in the FMS exactly the same as a mandatory crossing altitude?&lt;/li&gt;&#xA;&lt;li&gt;Are expected altitudes treated as suggestions by pilots or controllers? For example, in the above chart, if you were at JHAWK 15,000ft landing south, and Kansas City Center or Approach told you to &quot;descend at your discretion, maintain 8000&quot;, would you (or the FMS) make any attempt to cross RUGBB at 12,000 even though it's not required?&lt;/li&gt;&#xA;&lt;li&gt;How common is it for ATC to actually issue a &quot;cross [fix] at [altitude]&quot; where the fix and altitude are as expected on the chart? And, if it is common, why wouldn't it simply be mandatory?&lt;/li&gt;&#xA;&lt;li&gt;Are expected altitudes part of lost communications procedures?&lt;/li&gt;&#xA;&lt;li&gt;Am I missing anything with regards to the purpose of expected altitudes?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-01-14T20:44:31.920" Title="How are &quot;expect&quot; altitudes on STARs used?" Tags="&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;sid-star&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2738" PostTypeId="2" ParentId="2737" CreationDate="2014-03-26T02:59:05.907" Score="6" Body="&lt;p&gt;Someone else will have to comment on whether the STAR in the FMS includes the altitudes as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right, &quot;expected&quot; altitudes are suggestions so that pilots know about when they will need to begin their descent. Instructions from ATC are the final word, so they would either say &quot;descend via&quot; or specify the altitude if they were using the &quot;expected&quot; altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC instruction to &quot;cross [fix] at [altitude]&quot; will depend on the traffic situation. Along busy approaches, it is fairly common. It's not mandatory because it's not always necessary. It is up to ATC to decide what altitude the pilots should be at, and it may not always be the &quot;expect&quot; altitude.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The “expect” altitudes/speeds are published so that pilots may have&#xA;  the information for planning purposes. These altitudes/speeds must not&#xA;  be used in the event of lost communications unless ATC has&#xA;  specifically advised the pilot to expect these altitudes/speeds as&#xA;  part of a further clearance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;nofollow&quot;&gt;AIM Section 4. Arrival Procedures&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="65" LastEditDate="2015-01-14T20:44:31.920" LastActivityDate="2015-01-14T20:44:31.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2739" PostTypeId="2" ParentId="2269" CreationDate="2014-03-26T03:20:25.043" Score="2" Body="&lt;p&gt;Re: INS - Since there are no ground based radio transmission navigation stations in the ocean (VOR's or ADF's), the INS (inertial navigation system) was designed to help jets navigate safely over the ocean (before GPS).  INS uses a series of gyroscopes and accelerometers to measure how far a plane has traveled from a specific point.  With multiple accelerometers it's able to figure if the plane turned to a specific heading and how far it's gone (it can do this through multiple turns and speed changes).  To set the airplanes INS, a pilot pulls up to a specific INS set point at an airport and calibrates it (before the trip).  INS is so accurate that it typically holds a planes position to within a few miles after traveling 2500 miles.  The INS system can also be set from a GPS.  The major advantage to INS is it doesn't rely on any external signal to work.&lt;/p&gt;&#xA;" OwnerUserId="1805" LastActivityDate="2014-03-26T03:20:25.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2740" PostTypeId="2" ParentId="2655" CreationDate="2014-03-26T05:00:56.470" Score="3" Body="&lt;p&gt;The answers are missing the point. Some companies have real time GPS enabled tracking on fleet trucks.  You can go on a computer and check where these trucks have been 1 week back. When some of you say GPS signals can't penetrate deep waters, it would have at least sent it's last known coordinates before impact that could have been recorded if there was a system in place to record. Then we could better pinpoint impact areas.&lt;/p&gt;&#xA;" OwnerUserId="1809" LastEditorUserId="97" LastEditDate="2014-03-26T08:34:00.843" LastActivityDate="2014-03-26T08:34:00.843" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2741" PostTypeId="2" ParentId="2619" CreationDate="2014-03-26T06:53:02.330" Score="5" Body="&lt;p&gt;Let's have a look at documentation of &lt;a href=&quot;http://aerospace.honeywell.com/~/media/UWSAero/common/documents/myaerospacecatalog-documents/BA_brochures-documents/Laseref_VI_FINAL.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;actual modern IRS&lt;/a&gt;. It says (on page 6) that if GPS data is lost, it will maintain RNP0.1 for 8 minutes, RNP0.3 for 20 minutes and RNP1 for 2 hours. That means that in 8 minutes the error is no more than 0.1 nautical mile with 95% confidence, in 20 minutes it is no more than 0.3 nm with 95% confidence and in 2 hours the error is no more than 1 nm again with 95% confidence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For general description how it works see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2275/what-is-an-inertial-navigation-system-how-does-it-work?rq=1&quot;&gt;What is an Inertial Navigation System? How does it work?&lt;/a&gt; and of course the appropriate &lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article&lt;/a&gt;. Basically it measures acceleration and rotation (with gyroscopes) and integrates it over time. Modern systems do the calculations digitally with sophisticated filters to smooth over some errors.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-03-26T07:01:50.507" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2742" PostTypeId="2" ParentId="1436" CreationDate="2014-03-26T07:18:16.050" Score="32" Body="&lt;p&gt;The question is vague, not specifying on which Boeing and Airbus pair the problem lies on. For example Boeing 377 Stratocruiser &lt;strong&gt;is&lt;/strong&gt; also a Boeing but I think there is very small possibility for someone to confuse it to an Airbus. Having said that, I consider a random pair of comparable aircraft, A320 (the left) and B734 (the right).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Nose&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;B734 has a more streamlined and &quot;pointy&quot; nose and a more streamlined &quot;forehead&quot;. Windshield is also different on B734 making that characteristic corner plus the &quot;eyebrows&quot; which are not though standard on all 737's (per Wikipedia). Also note the much shorter nose gear of the 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SD8ji.png&quot; alt=&quot;Nose Comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Engines&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;B734 engine is thinner with the characteristic flattening at the bottom of it. The engine cover is also longer in B734.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/I6viB.png&quot; alt=&quot;Engine Comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also if you have the chance to have a front side look of the planes, then the flattening of 737's CFM is even more prominent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/P1SgP.png&quot; alt=&quot;Front comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the blueprint can't be as descriptive as a picture, you may have a look in &lt;a href=&quot;https://aviation.stackexchange.com/q/7824/878&quot;&gt;this question&lt;/a&gt; where there are some excellent photos of the 737's engines&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jan Hudec correctly pointed out that Airbus A320 comes with 2 different engine types. I would &lt;em&gt;guess&lt;/em&gt; from the blueprint that the pictured A320 &quot;wears&quot; the CFM56.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Tail&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;B734 has a &lt;a href=&quot;https://aviation.stackexchange.com/q/14786/878&quot;&gt;dorsal fin&lt;/a&gt; (present from B733 onward) while &lt;a href=&quot;https://aviation.stackexchange.com/q/25108/878&quot;&gt;A230 doesn't&lt;/a&gt;. Also the fin and horizontal stabilizers/stabilators are located much closer to the fuselage end in B734 compared to A320&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FFw8J.png&quot; alt=&quot;Tail comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those are the &lt;strong&gt;obvious&lt;/strong&gt; (in my opinion) differences. For further you can Google (as already mentioned), simply observe (as I already mentioned but deleted it) and do the same for any other pair of aircraft you have difficulties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Images are from wikipedia, so I think it will be easy thing doing the same for other types as well.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2017-08-28T09:19:11.017" LastActivityDate="2017-08-28T09:19:11.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2743" PostTypeId="2" ParentId="2726" CreationDate="2014-03-26T07:20:03.267" Score="20" Body="&lt;p&gt;Mainly the options 2 and 1 from your list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What nobody mentioned so far, but is rather important here is that the angle of attack depends on &lt;em&gt;speed&lt;/em&gt;&lt;sup&gt;1&lt;/sup&gt; and &lt;em&gt;weight&lt;/em&gt;. While the &quot;speed&quot; does not vary much for most airliners, the difference between empty and fully loaded airliner is rather large.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if the fuselage was tilted down, it would generate lift directed down and associated drag with the net result of simply a lot of extra drag. So the aircraft is designed so that it does not fly (in level cruise) pitched down even when light. But that means that when it is fully loaded, it flies slightly pitched up, because it needs more lift and higher angle of attack to get it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;&amp;nbsp;It depends on the &quot;indicated speed&quot;, which is not speed at all but rather dynamic pressure expressed as speed at which it would occur when moving through air of standard sea level pressure (1013.25 hPa). The pressure at high altitudes where airliners normally fly is significantly lower, so the indicated speed is usually does not exceed 250 knots when true speed is well over 400 knots.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-03-26T07:20:03.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2744" PostTypeId="1" AcceptedAnswerId="2746" CreationDate="2014-03-26T09:54:40.987" Score="8" ViewCount="1641" Body="&lt;p&gt;As a thought experiment, imagine a plane with minimal fuel/appliances on board with hundreds of heavy passengers that make up say 10% of the weight of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now imagine that they have a way to synchronize a jump where temporarily for 0.5s they are airborne in relation to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(NOTE: If idea of so many heavy passengers is troublesome to you, assume this is a cargo carrier with spring loaded &quot;widgets&quot; that have ability to be programmed to &quot;jump&quot; at once.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Can flight dynamics be affected due to the jump at ANY phase of the flight?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What % of the typical (cargo/passanger) plane weight is the actual cargo (excluding fuel)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the location of the &quot;jumping&quot; cargo matter?  Tail vs. Cockpit&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What happens if all pax/cargo suddenly jumped to tail or cockpit section?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Everybody jump!&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="795" LastEditDate="2014-03-26T12:35:59.143" LastActivityDate="2014-03-26T12:47:53.160" Title="What happens when all passengers jump at once?" Tags="&lt;passenger&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2745" PostTypeId="1" AcceptedAnswerId="8538" CreationDate="2014-03-26T10:07:43.557" Score="9" ViewCount="2290" Body="&lt;p&gt;Does Russia still use the normative (Russian) brake friction when reporting &lt;a href=&quot;http://www.baseops.de/snowtam.php&quot; rel=&quot;nofollow&quot;&gt;Snowtams&lt;/a&gt; for their airports? What about former Soviet (CIS) countries?&lt;/p&gt;&#xA;" OwnerUserId="1816" LastEditorUserId="1696" LastEditDate="2015-04-22T00:37:33.933" LastActivityDate="2019-12-16T16:27:20.717" Title="Does Russia still use a Snowtam to report normative brake friction?" Tags="&lt;commercial-aviation&gt;&lt;pilots&gt;&lt;cold-weather&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2746" PostTypeId="2" ParentId="2744" CreationDate="2014-03-26T10:13:10.390" Score="9" Body="&lt;p&gt;I will assume that the starting condition is level flight.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;yes. momentarily the assumption of &quot;rigid body&quot; would not be satisfied. Also, for that 0.5s the aircraft would not be in contact with 10% of the weight, assuming constant thrust and velocity, you would have 10% more lift than weight, making the aircraft rise a bit before descend again when all the passengers land again. Velocity would not be greatly affected, as the drag would remain unchanged (no external change in shape or large attitude variations)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the difference between zero-fuel weight (ZFW) and Dry Operating weight (DOW) is probably what you are looking for. Airbus defines it as the &quot;total traffic load&quot;. If you want to add catering, cabin equipment and the crew, you then take the difference between the ZFW and the Manufacturer's Empty Weight (MEW). As a percentage it can vary wildly based on the aircraft class (class 23 has much less cargo/passenger space that a class 25, for example)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;yes. think of a beam in equilibrium on a pivot located at half its length: if you push just above the pivot, the beam will not rotate, any other location will cause it to rotate and flip over. This does not mean that the aircraft might flip over, as the beam is an uncontrolled and unstable system, while the aircraft is controlled, but it is a comparison that can help visualize the effect&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I would define it more as shifting rather than jumping. This is a totally different scenario: the center of gravity at the end of this &quot;jump&quot; would be in a totally different location w.r.t. the start of the experiment, something that instead was not happening in the previous scenarios. By shifting the location of the center of gravity is likely that it might exceed the specified position limits and cause the airplane to be uncontrollable, to pitch up or down (depending if you shift the passengers backwards or forwards) and stall or nose-dive. On large aircrafts it is obviously not easy to achieve such unsafe scenario, as the cargo will be usually much heavier than the passengers, limiting the extent of the CG shift.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-03-26T12:47:53.160" LastActivityDate="2014-03-26T12:47:53.160" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2747" PostTypeId="2" ParentId="2726" CreationDate="2014-03-26T10:44:38.850" Score="4" Body="&lt;p&gt;I believe the answer may be option 5:&lt;br&gt;&lt;br&gt;&#xA;5. The aircraft changes during flight.&lt;br&gt;&lt;br&gt;&#xA;At the beginning of a flight an aircraft is loaded with fuel. This increases the weight of the aircraft and thus requires an increase in the AoA to maintain level flight. As the aircraft burns fuel the mass of the aircraft decreases and consequently the AoA must decrease also.&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the aircraft type and the length of the flight, the weight of the fuel can be very significant. For example, a Boeing 777-200 has a maximum fuel capacity of 117,340 lts. This ammount of fuel weighs aprox. 95,000 kg. The maximum take off weight for this type of aircraft is slightly over 247,000 kg. This means that a 777 fully loaded with fuel and with maximum take off weight will lose a bit less than 40% of its mass during flight.&lt;/p&gt;&#xA;" OwnerUserId="1817" LastEditorUserId="774" LastEditDate="2014-03-26T13:02:02.110" LastActivityDate="2014-03-26T13:02:02.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2748" PostTypeId="2" ParentId="2619" CreationDate="2014-03-26T10:48:23.630" Score="1" Body="&lt;p&gt;In addition to Jan's answer, there are other means than GPS to provide location data to an INS.&lt;br/&gt;&#xA;VOR and NBD triangulation has been used for decades, long before GPS even existed.&lt;br/&gt;&#xA;And there's always the good old sextant, which a trained crew member can use to get a pretty accurate position with, in combination with a good clock.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Both can provide location information to update an INS. Of course the update will only be as good as the skill of the crew performing the position calculation.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-26T10:48:23.630" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2749" PostTypeId="2" ParentId="2723" CreationDate="2014-03-26T10:52:31.923" Score="0" Body="&lt;p&gt;One other theory I've heard (but been unable to verify) about the origin of the term &quot;black box&quot; in popular literature is that the boxes when found often tend to be black.&lt;br/&gt;&#xA;Not as a result of being painted black, but as a result of having been inside a burning aircraft wreck, covered in soot and burnt paint.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Whether that's the (or even one of the) reason for the term is probably lost in the mists of time. I seriously doubt it's ever been written down by the people inventing the term (newspaper journalists most likely) what their reasoning was.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-26T10:52:31.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2750" PostTypeId="2" ParentId="2723" CreationDate="2014-03-26T11:22:50.133" Score="10" Body="&lt;p&gt;The correct answer seems to be, &quot;Nobody knows for sure&quot; but here's some data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The earliest citation in the Oxford English Dictionary for the phrase &quot;black box&quot; referring specifically to a flight data recorder isn't until 1964, from the UK &lt;em&gt;Daily Telegraph&lt;/em&gt;: &quot;The flight recorder is an indestructible 'black box' which automatically records the key functions in the aircraft...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are earlier uses of the phrase, with different meanings. Since 1932, it has been used to mean a device whose internal workings are unclear but which is specified by its inputs and outputs; since 1945, it has been used in the Royal Air Force to refer to various navigational devices which, according to &lt;a href=&quot;https://en.wikipedia.org/wiki/File%3aJ_M_Briscoe24_07_200713_05_14IMG2104_GEE_AIRBORNE.JPG&quot;&gt;Wikipedia&lt;/a&gt; sometimes were housed in literal boxes that were black.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My interpretation/thoughts/speculation/whatever word you want to use:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of quote marks in the &lt;em&gt;Daily Telegraph&lt;/em&gt; seems significant. First, it suggests that we're not talking about a literal box which is black and you might imagine they'd say something like &quot;&amp;nbsp;'black box' (which is now actually orange)&quot; if they were formally literal black boxes. Second, &quot;a 'black box'&amp;nbsp;&quot; suggests that the FDR might be just one of several devices on a plane that could be described as &quot;black boxes&quot;. Unfortunately, that seems consistent with both of the other given definitions: you could perfectly well imagine it being RAF-style slang for &quot;This electronic box of tricks does navigation, this one holds the autopilot and this one records flight data&quot; or the input-output version of &quot;I don't know exactly how the autopilot works, but I know what it does; ditto the navigation system; ditto the data recorder.&quot;&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-03-26T11:22:50.133" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2752" PostTypeId="1" CreationDate="2014-03-26T12:24:41.973" Score="12" ViewCount="473" Body="&lt;p&gt;In the US, there's a TFR everywhere a designated VIP (US president or vice president) is going to be. When (most?) foreign VIPs visit the US, I don't think there are TFRs in place for them (unless the location coincides with our VIPs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there TFRs (or international equivalents) in other countries when the US VIPs are there?&lt;/p&gt;&#xA;" OwnerUserId="73" LastEditorUserId="1696" LastEditDate="2015-04-23T15:07:19.497" LastActivityDate="2015-04-23T15:07:19.497" Title="Do other countries create the equivalent of a TFR when US VIP's visit?" Tags="&lt;usa&gt;&lt;tfr&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2753" PostTypeId="1" AcceptedAnswerId="2760" CreationDate="2014-03-26T13:20:08.033" Score="7" ViewCount="1201" Body="&lt;p&gt;Since an &lt;a href=&quot;http://en.wikipedia.org/wiki/Electronic_flight_bag&quot; rel=&quot;nofollow&quot;&gt;electronic flight bag (EFB)&lt;/a&gt; is basically an iPad with the right app installed, is it possible that some sort of plane-tablet connection could be formed (either wireless or wired) to automate all of most of an EFB pre-flight check? Or does aviation regulation not allow this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a purely hypothetical question since I don't think any EFB app so far supports this, let alone any plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clarification: I'm talking about the preflight checks that ensure that everything in the cockpit is set up correctly for takeoff. I understand that an EFB is an electronic version of the 40 pounds of paper a pilot usually needs in the cockpit. Can this preflight check be done on the EFB? And can this be automated?&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="65" LastEditDate="2015-03-04T21:14:08.270" LastActivityDate="2015-03-04T21:17:21.313" Title="Could an EFB-based pre-flight check be automated?" Tags="&lt;preflight&gt;&lt;efb&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2754" PostTypeId="1" AcceptedAnswerId="2769" CreationDate="2014-03-26T13:30:12.173" Score="15" ViewCount="2529" Body="&lt;p&gt;Something I noticed while flying - while on takeoff it feels as if the plane is tilting upwards even though the plane is clearly still on the ground with all sets of landing gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the nose gear extend immediately upon acceleration to perhaps generate more lift? Or maybe it's just an illusion caused by the acceleration. (I've only noticed this on large aircraft - like for example: Airbus A320 or Boeing 737.)&lt;/p&gt;&#xA;" OwnerUserId="1824" LastEditorUserId="97" LastEditDate="2014-04-09T00:48:34.930" LastActivityDate="2014-10-16T15:43:30.943" Title="Does an aircraft's nose landing gear extend on take off?" Tags="&lt;aerodynamics&gt;&lt;passenger&gt;&lt;takeoff&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2755" PostTypeId="2" ParentId="2754" CreationDate="2014-03-26T13:44:37.057" Score="2" Body="&lt;p&gt;I will assume you refer to the initial acceleration when you speak of &quot;while on takeoff&quot;, since after the rotation the answer would be quite tautological.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's be clear, the nose gear does not &quot;extend&quot; anywhere during take-off since its damper/shock absorber is not an active component, but rather a passive one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect you are feeling is due to the acceleration and the inertia of the aircraft: the engines of a large aircraft sit below the Center of Mass which will incur a rotational force to the aircraft, lifting the nose up a bit. The weight will be &quot;sitting&quot; more on the main gear rather than the nose, you have a similar effect on a car or, more notably, on an accelerating motorcycle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also have the reverse effect when decelerating: the weight will tend to stress more the nose gear rather than the main gear, the same way a motorcycle tends to &quot;sit&quot; on the front wheel when stopping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On aircraft with the engines up high the rotational force will be reversed until the elevators have enough airflow to counteract it.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="609" LastEditDate="2014-03-26T13:57:05.970" LastActivityDate="2014-03-26T13:57:05.970" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="2756" PostTypeId="2" ParentId="2198" CreationDate="2014-03-26T13:51:35.597" Score="2" Body="&lt;p&gt;I haven't read through all of these responses, but most focus on locating the plane going down in the middle of the ocean, as well as major new equipment and transmitters. First, the location wouldn't have to be a separate GPS transmitter. It only needs to be voice or text transmitting the location data which the plane already has. Whatever the communication of the location data, it doesn't have to be relayed at the point of impact or damage. Obviously, that would be most helpful, but in the case of MH370 - and especially if it was flying in a straight line, then having 2 points would be helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is, if the plane is detected over Malaysia, then over the Indian Ocean, they would have a path and relative search area based on fuel, etc. It's not perfect, but simply a transponder that can't be turned off would probably have been sufficient enough to detect the general area of the aircraft in the first week. There needs to be satellite tracking in real-time, but I think there are sufficient systems in place already that would have made this much easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, and in response to the earlier post about \$300M system, if a person sat on a plane and texted lat/long every 15 seconds, they would find this plane much quicker even if it went beyond text towers. I'm not suggesting having a person do that, but you can create a device that does that for a relatively small amount of \$. It's not the perfect system, but is better than nothing.&lt;/p&gt;&#xA;" OwnerUserId="1826" LastEditorUserId="72" LastEditDate="2014-04-23T12:44:56.233" LastActivityDate="2014-04-23T12:44:56.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2758" PostTypeId="2" ParentId="1436" CreationDate="2014-03-26T14:15:24.920" Score="13" Body="&lt;p&gt;Further to the above answers, at night Airbus aircraft can be identified due to their unique strobe flash sequences. While all other aircraft strobes flash once, Airbus strobes flash twice, i.e&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;flash flash&lt;/em&gt; pause &lt;em&gt;flash flash&lt;/em&gt; pause -  Airbus&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;flash&lt;/em&gt; pause &lt;em&gt;flash&lt;/em&gt; pause - Non-Airbus aircraft&lt;/p&gt;&#xA;" OwnerUserId="1720" LastActivityDate="2014-03-26T14:15:24.920" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2760" PostTypeId="2" ParentId="2753" CreationDate="2014-03-26T14:42:14.893" Score="8" Body="&lt;p&gt;An EFB could not be used for this purpose, all your suggestion would do is replicate things that are already done by &lt;a href=&quot;http://en.wikipedia.org/wiki/Engine-indicating_and_crew-alerting_system&quot; rel=&quot;nofollow&quot;&gt;EICAS&lt;/a&gt; (engine indication and crew alert system).  The reason for this is that &quot;receiving&quot;, &quot;pre-flight&quot; and &quot;before takeoff&quot; checklists all involve physically moving switches.  The EFB would be unable to perform these actions (e.g. an EFB cannot select flaps 9 degrees).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What an EFB could do, if tied into the aircraft ARINC data bus, is to verify things.  Such an EFB could verify that flaps are indicating a set position and could alert us if it were not.  However, as mentioned, the EICAS already does this, and if I were to advance a thrust lever beyond taxi power I would get a master warning and a takeoff configuration EICAS message as well as an aural warning &quot;TAKEOFF FLAPS&quot; (EMB-145).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also mention the bulk of paper carried as a reason for this, but this is not relevant to the checklists.  The checklist on many large airplanes is a single sheet of paper, laminated and installed in the airplane.  Some airplanes may have a few sheets, but overall checklists account for very little paperwork and they belong to the airplane, not the pilots.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where EFBs do help with paperwork are the approach charts, which account for 75% of what I carried on any given flight.  Three 2&quot; binders, full of nothing but approach plates.  An EFB can condense that down to a tablet, and this is where the value of the EFB is.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="65" LastEditDate="2015-03-04T21:17:21.313" LastActivityDate="2015-03-04T21:17:21.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2761" PostTypeId="1" AcceptedAnswerId="2763" CreationDate="2014-03-26T14:56:45.157" Score="19" ViewCount="7415" Body="&lt;p&gt;Are pilots armed to defend themselves in event of a terrorist attack? It seems that in view of terrorist attacks and hijackings since 9/11 they would be.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-04-09T00:26:02.037" LastActivityDate="2014-04-09T00:26:02.037" Title="Are pilots armed?" Tags="&lt;security&gt;&lt;terrorism&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2762" PostTypeId="2" ParentId="2761" CreationDate="2014-03-26T15:01:21.973" Score="19" Body="&lt;p&gt;Some are -- in the US.  The TSA has a program called &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Flight_Deck_Officer&quot;&gt;Federal Flight Deck Officer (FFDO)&lt;/a&gt; that involves training from the US Federal Marshals.  The pilots who participate in this program are armed but will not display that status when in view of the public so you will normally be unable to identify them.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-26T15:06:56.503" LastActivityDate="2014-03-26T15:06:56.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2763" PostTypeId="2" ParentId="2761" CreationDate="2014-03-26T15:11:57.290" Score="23" Body="&lt;p&gt;Some pilots are armed, like casey says. Most, however, are not. And they have very little reason to:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;After 9/11, a lot stricter security measures have been made on all airplanes to limit the access non-essential staff has to the cockpit. This includes measures like a reinforced locked door between the cabin and cockpit.&lt;/li&gt;&#xA;&lt;li&gt;Because of the improved measures, terrorists these days are less inclined to use the plane as a weapon, choosing instead to use bombs in their shoes, underwear or carryon luggage to detonate the plane.&lt;/li&gt;&#xA;&lt;li&gt;A gun on a plane can be dangerous, especially in the cockpit. it can hit vital instrumentation, damage the fuselage or a window, or cause friendly fire.&lt;/li&gt;&#xA;&lt;li&gt;In the confined space of an airplane, some self-defense training is likely to be more useful than a gun. in addition to collateral damage, a gunshot can cause the passengers to panic. An assailant can also steal the gun, giving even more cause for concern.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1823" LastActivityDate="2014-03-26T15:11:57.290" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2764" PostTypeId="2" ParentId="1072" CreationDate="2014-03-26T15:21:20.183" Score="17" Body="&lt;p&gt;A &quot;Joint Base&quot; does not refer to joint military and civilian, it refers to Joint as in co-use by multiple branches of the services.  If you show up unannounced as an emergency aircraft, they will not point guns at you or detain you, they will simply handle your situation, provide the help and resources you need to get the aircraft back in the air and send you in your way.  There are only a couple bases that have &quot;security at the ready&quot; and will meet you with armed individuals.  The military is not some war-crazed institution waiting to shoot people, the bases are staffed with civilian controllers as well as a military and they are there to help when and where they can in aviation.  My experience flying both military and civilian aircraft for over 30 years has only produced professional accolades for the folks on the bases around the world.  If you have official business, it should be easy to land there with prior permission, if not- don't go or ask. If you have an emergency, do not hesitate to use the installation, it is funded by your tax dollars and they will be happy to share.  &lt;/p&gt;&#xA;" OwnerUserId="1829" LastActivityDate="2014-03-26T15:21:20.183" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2766" PostTypeId="1" AcceptedAnswerId="2767" CreationDate="2014-03-26T16:08:23.807" Score="13" ViewCount="6302" Body="&lt;p&gt;I know the usual scenario is where an airliner suffers from an explosive decompression and the oxygen masks drop and the plane descends to a safer altitude but.....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a purely hypothetical situation but if a passenger plane was cruising at 39000ft+ and it suffered a cabin leak that somehow went unnoticed by the crew and passengers and the oxygen masks didn't drop, how long roughly would it be before the passengers were incapacitated, and how long before the lack of oxygen became fatal.&lt;/p&gt;&#xA;" OwnerUserId="1831" LastEditorUserId="64" LastEditDate="2015-02-27T07:41:28.330" LastActivityDate="2015-02-27T07:41:28.330" Title="How long will one remain conscious in the event of a sudden cabin depressurization?" Tags="&lt;passenger&gt;&lt;cabin-pressure&gt;&lt;oxygen&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2767" PostTypeId="2" ParentId="2766" CreationDate="2014-03-26T16:26:54.093" Score="17" Body="&lt;p&gt;The question you're asking roughly translates to &lt;code&gt;What is the time of useful consciousness at 39,000 feet?&lt;/code&gt;. The answer is &quot;About 15-20 seconds, once the pressure bleeds off.&quot; The FAA has a handy table for this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Aiw3n.png&quot; alt=&quot;Time of Useful Consciousness&quot;&gt;&lt;br&gt;&#xA;From Chapter 16 of the Pilot Handbook of Aeronautical Knowledge.&lt;br&gt;&#xA;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2016.pdf&quot; rel=&quot;noreferrer&quot;&gt;You can get a PDF of Chapter 16 here&lt;/a&gt;, or &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;noreferrer&quot;&gt;you can grab the whole thing from the FAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The Time of Useful Consciousness will vary depending on personal physiological factors (e.g. if you're a smoker your blood doesn't oxygenate as well - you will probably have less time. If you're a mountain climber in excellent shape and used to breathing rarified air on your climbs you'll probably have a little more time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a non-explosive decompression (say a pressurization system failure) you'll probably have more time than this from the start of the event to the point where everyone is unconscious: the cabin pressure will take time to bleed off. Whether that time is seconds or minutes depends on the nature of the leak.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably while the pressure is bleeding off the aircraft's systems will complain about the loss of cabin pressure and give the pilots a chance to address the problem (fix the pressurization system or descend to a safe altitude). Unfortunately the effects of hypoxia can start setting in before the crew realizes what's going on (which is one of the contributing factors in the loss of &lt;a href=&quot;http://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;noreferrer&quot;&gt;Helios Flight 522&lt;/a&gt;, which suffered just this kind of gradual depressurization).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-26T16:26:54.093" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2768" PostTypeId="2" ParentId="2754" CreationDate="2014-03-26T16:51:12.373" Score="6" Body="&lt;p&gt;I'm assuming you are referring to the 'tilting backwards' that occurs when the aircraft begins its takeoff run. There is of course a much more pronounced tilting backwards when the nosewheel actually lifts off the runway, a few seconds before the main wheels come off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tilting at the start of the takeoff run is actually a sensory illusion. It's caused by the acceleration of the aircraft. The forward force on you from the seat is combining with the upward force (resisting gravity) makes it seem as though the aircraft is tilting, when in fact it isn't. You would get a similar effect in a fast-accelerating sports car; however in a car you have a clear view of the outside world which means your mind can understand that this is acceleration, not a tilt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can check this in a number of ways: 1) if you &lt;a href=&quot;https://www.youtube.com/watch?v=Qny8M0NcPg4&quot;&gt;watch a plane taking off from outside&lt;/a&gt;, there is no noticeable tilt of the plane, nor any noticeable change in the nosewheel extension - certainly nothing like as much as the tilt appears to be from the inside 2) Looking at the outside world through the window will confirm that the plane is not tilting 3) This effect occurs on planes with engines both above and below the wings, which you would not expect if it were an actual tilt.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2014-03-26T17:17:37.523" LastActivityDate="2014-03-26T17:17:37.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2769" PostTypeId="2" ParentId="2754" CreationDate="2014-03-26T17:15:40.407" Score="41" Body="&lt;p&gt;No, the gear doesn't actively extend, and any passive change to the strut extension during takeoff is likely to be &lt;strong&gt;imperceptible&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you &lt;em&gt;are&lt;/em&gt; perceiving during takeoff is the &lt;strong&gt;&lt;a href=&quot;http://books.google.com/books?id=VWwtAgAAQBAJ&amp;amp;pg=PT136&amp;amp;dq=somatogravic%20illusion&amp;amp;hl=en&amp;amp;sa=X&quot;&gt;somatogravic illusion&lt;/a&gt;&lt;/strong&gt;. It is a physiological sensation, not a physical change. Rapid acceleration, as during a takeoff roll, causes the inner ear to report what your brain assumes is your head tilting back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.nasa.gov/audience/forstudents/9-12/features/F_Human_Vestibular_System_in_Space.html&quot;&gt;&lt;strong&gt;otolith organs&lt;/strong&gt; in your inner ears&lt;/a&gt; sit in fluid and detect the tilt of your head. Acceleration and pitching up (or tilting back) cause the exact same movement of the otoliths. Because the otoliths are pushed backwards by the fluid, just like they would by you tilting your head back, it feels like a climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airliner is taking off, you have limited outside references to the horizon and your inner ear takes over the task of orienting you. You might notice it in smaller aircraft if you closed your eyes; in very small aircraft, the acceleration may be too slow to trigger the illusion.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-10-16T15:43:30.943" LastActivityDate="2014-10-16T15:43:30.943" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2770" PostTypeId="1" AcceptedAnswerId="2771" CreationDate="2014-03-26T17:57:13.173" Score="3" ViewCount="332" Body="&lt;p&gt;I noticed that no planes heading to &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ivato_International_Airport&quot; rel=&quot;nofollow&quot;&gt;FMMI&lt;/a&gt;&lt;/strong&gt; are plotted on all the prominent online radars despite the fact that most of them are likely equipped with ADS-B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does it take to remedy that lack of coverage?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="65" LastEditDate="2015-02-26T16:04:42.793" LastActivityDate="2015-02-26T16:04:42.793" Title="Why there is no online radar coverage of Madagascar?" Tags="&lt;ads-b&gt;&lt;online-tracking&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2771" PostTypeId="2" ParentId="2770" CreationDate="2014-03-26T18:19:08.803" Score="4" Body="&lt;p&gt;For services like FlightRadar24 they typically get data in two ways: via volunteers hosting ADS-B receiver stations on the ground, and directly from the ATC radar system in places where that data is readily available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the ADS-B equipped aircraft these services would need volunteers in the area of Ivato Airport (FMMI) to host ADS-B receivers. &lt;a href=&quot;http://www.flightradar24.com/increase-coverage&quot; rel=&quot;nofollow&quot;&gt;They would almost certainly be happy to have more receivers&lt;/a&gt;, and they even offer free &quot;premium&quot; services (and occasionally free receivers) to people who help provide data. If it's legal in your area, and you are willing to run a receiver station you may want to look into it, and this will get you aircraft which are broadcasting ADS-B data (Mode S+ES with GPS position information). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the aircraft which are not broadcasting ADS-B information (because they lack an appropriate transponder or GPS system) the problem is a little more complicated - the organization that runs ATC in Madagascar would need to set up radar sites (which presumably exist), and make that information publicly available (which may or may not be the case). A system would then need to be developed to allow the online radar services to process that data and make the flight tracks available (subject to whatever delays may be imposed in that process).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I don't know much (&lt;em&gt;anything&lt;/em&gt; really) about the ATC system in Madagascar, so I'm not sure how robust the radar infrastructure is or how open they might be with their data, so I can't really comment on that half of the system.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-26T18:19:08.803" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2772" PostTypeId="1" AcceptedAnswerId="2774" CreationDate="2014-03-26T18:25:00.883" Score="13" ViewCount="3510" Body="&lt;p&gt;I was doing research about jet engines, and they seem really difficult to fully understand. So, can anyone explain it in a simple way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GhGoc.jpg&quot; alt=&quot;Jet Engine Image&quot;&gt;&lt;br&gt;&#xA;An afterburner glows on an F-15 Eagle engine, source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F100_F-15_engine.JPG&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do &lt;strong&gt;jet engines&lt;/strong&gt; work?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="3201" LastEditDate="2016-11-17T22:24:06.373" LastActivityDate="2020-11-17T14:10:05.040" Title="How do jet engines work?" Tags="&lt;jet-engine&gt;&lt;jet&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2773" PostTypeId="1" CreationDate="2014-03-26T18:31:30.293" Score="12" ViewCount="1516" Body="&lt;p&gt;I'm wondering if say, hypothetically, I had a friend who had a &lt;strong&gt;large aircraft (e.g. Learjet), could I do my PPL hours on it from day one&lt;/strong&gt;, or is there anything stopping this? &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-03-27T12:47:23.033" LastActivityDate="2014-03-27T12:47:23.033" Title="Are you allowed to do your entire PPL on a medium-sized jet aircraft from day one?" Tags="&lt;easa-regulations&gt;&lt;ppl&gt;&lt;jet&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2774" PostTypeId="2" ParentId="2772" CreationDate="2014-03-26T18:39:16.340" Score="21" Body="&lt;h2&gt;&lt;strong&gt;In the simplest of terms:&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Suck&lt;/strong&gt; - Air is sucked into the turbine. &lt;em&gt;For efficiency reasons, most aircraft let some of that just pass through the outer part of the fan, rather than through the whole engine.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Squeeze&lt;/strong&gt; - The compressor squeezes that air together to a high pressure. This helps with ignition.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Boom&lt;/strong&gt; - Fuel is injected and ignited. As the air gets hot, it expands.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Blow&lt;/strong&gt; - The hot air drives the low-pressure turbine (driving the whole shaft holding the engine together), sucking new air in, and is itself blown out the back.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/c/c0/Turbofan_operation.png&quot; alt=&quot;jet&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:47.947" LastActivityDate="2014-03-26T18:39:16.340" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2775" PostTypeId="2" ParentId="2772" CreationDate="2014-03-26T18:43:27.830" Score="1" Body="&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow&quot;&gt;jet engine&lt;/a&gt; is an overcomplicated &lt;a href=&quot;http://en.wikipedia.org/wiki/Ramjet&quot; rel=&quot;nofollow&quot;&gt;ramjet&lt;/a&gt; with extra turbines to let it work at lower speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ram jet works by igniting compressed incoming by mixing it with fuel and providing a spark.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-03-26T18:43:27.830" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2776" PostTypeId="2" ParentId="1707" CreationDate="2014-03-26T19:05:16.823" Score="5" Body="&lt;p&gt;As Ralgha stated, this kind of callout would be included in the SOP. A couple I found in searching were the &lt;a href=&quot;http://www.nbaa.org/admin/sms/manual/StandardOperatingProcedures-FixedWing.doc&quot; rel=&quot;nofollow&quot;&gt;NBAA&lt;/a&gt; (same in their helicopter procedures by the way) and &lt;a href=&quot;http://www.angelflightne.org/images/Docs/pilot_safety_manual.pdf&quot; rel=&quot;nofollow&quot;&gt;Angel Flight NE&lt;/a&gt;, as well as some generic CRM guides. The &lt;a href=&quot;http://books.google.com/books?id=jxcnAgAAQBAJ&amp;amp;pg=PT237&amp;amp;lpg=PT237&amp;amp;dq=1000%20feet%20to%20assigned%20altitude%20callout&amp;amp;source=bl&amp;amp;ots=WXlrvmo0wJ&amp;amp;sig=Im7aXWkRdC7XNAthQq_iGZj2IE0&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=NjEzU_biM4PtoASKr4HwAQ&amp;amp;ved=0CDcQ6AEwAw#v=onepage&amp;amp;q=1000%20feet%20to%20assigned%20altitude%20callout&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;FAA Instrument Procedures Handbook&lt;/a&gt; also mentions altitude callouts, suggesting something like &quot;two to go&quot; and &quot;one to go&quot; (in thousands).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NBAA includes this specific phrasing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The callout is to include the altitude vacating and the assigned&#xA;  altitude i.e. “Six thousand for seven thousand” or “Flight level&#xA;  three-zero-zero for two-niner-zero”. After the PF makes this call, the&#xA;  PNF will verify and validate the call by stating “check”.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.skybrary.aero/solutions/levelbust/ResPool/FS_AltAw.pdf&quot; rel=&quot;nofollow&quot;&gt;Flight Safety Digest&lt;/a&gt; mentions that USAir used to use the &quot;two to go&quot; and &quot;one to go&quot; phrasing, but opted to change this for the same that the NBAA uses. The new policy has the pilot flying make this call, since they are in control of the climb, and makes it more clear what the final altitude will be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Flight Safety Foundation went in to &lt;a href=&quot;http://flightsafety.org/aerosafety-world-magazine/july-2010/error-trap&quot; rel=&quot;nofollow&quot;&gt;a bit more detail&lt;/a&gt; about the &quot;why&quot; behind the callout. They mentioned that in their observations, the callout was sometimes not done due to workload of other more important things going on in approach/descent. They explain the benefit:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This is not to suggest that the 1,000-ft callout is trivial. On the&#xA;  contrary, it ensures that both pilots concur about the altitude&#xA;  target, directs the attention of a flying pilot who might be&#xA;  distracted back to the impending level-off and draws both pilots’&#xA;  attention to what the autopilot is supposed to be doing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another resource that suggests the important is a report of an aircraft overshooting its altitude by 600 feet because the callout was missed. This report is in the &lt;a href=&quot;http://asrs.arc.nasa.gov/overview/database.html&quot; rel=&quot;nofollow&quot;&gt;ASRS database&lt;/a&gt;, report number 317750.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also found it referenced in &lt;a href=&quot;http://books.google.com/books?id=Jc4jYEAiOTsC&amp;amp;pg=PA10&amp;amp;lpg=PA10&amp;amp;dq=faa%20callout%20at%201,000%20ft.%20prior%20to%20the%20assigned%20altitude&amp;amp;source=bl&amp;amp;ots=u88SEH_5cH&amp;amp;sig=pBcUZkr6Csz_DzdU8xF8eH4RqSc&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=hhozU85ClrGhBMDagfgE&amp;amp;ved=0CCwQ6AEwAQ#v=onepage&amp;amp;q=faa%20callout%20at%201,000%20ft.%20prior%20to%20the%20assigned%20altitude&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;this book&lt;/a&gt; about communication. They didn't really comment on it specifically, but used it as an example of how communication is critical. Specifically, the more exactly the terminology is defined, the more clear the communication will be.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-03-26T20:10:05.460" LastActivityDate="2014-03-26T20:10:05.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2777" PostTypeId="1" CreationDate="2014-03-26T19:38:52.223" Score="7" ViewCount="1918" Body="&lt;p&gt;In the Slashdot article &lt;a href=&quot;http://beta.slashdot.org/story/199837&quot; rel=&quot;nofollow&quot;&gt;Is the Tesla Model S Pedal Placement A Safety Hazard?&lt;/a&gt; it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;what aviation analysts call a 'design-induced pilot error'&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I tried to search for &lt;code&gt;design-induced pilot error&lt;/code&gt; on Google, but found things too complex to understand! What does this mean?&lt;/p&gt;&#xA;" OwnerUserId="1837" LastEditorUserId="97" LastEditDate="2014-04-11T15:54:35.297" LastActivityDate="2014-04-11T15:54:35.297" Title="What does &quot;design-induced pilot error&quot; means?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2778" PostTypeId="2" ParentId="2777" CreationDate="2014-03-26T19:45:15.030" Score="20" Body="&lt;p&gt;The phrase is basically saying that bad design causes people to make mistakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Design-induced&lt;/strong&gt; - the interaction design or user experience is problematic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pilot error&lt;/strong&gt; - the pilot made a mistake. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of this would be the placement of a flap handle next to a gear lever, making it possible to raise the gear rather than the flaps after landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine controls in modern designs now feature different shapes for each control knob for similar reasons. There have been many accidents where pilots have grabbed a mixture knob — and shut an engine off completely — when they meant to grab the throttle and reduce power. Different textures and shapes make that harder to do:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0WzOk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-26T20:14:22.073" LastActivityDate="2014-03-26T20:14:22.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2779" PostTypeId="2" ParentId="258" CreationDate="2014-03-26T19:53:33.877" Score="3" Body="&lt;h3&gt;Theory&lt;/h3&gt;&#xA;&lt;p&gt;As voretaq7 notes, the pilots are the first limiting factor here. We can put a submarine crew underwater for 3 months at a time. Could we do the same on a plane? Maybe someday. The International Space Station is an example of what is possible as far as crew rotations. Of course, energy to fly in the atmosphere and external maintenance would pose some problems for an aircraft.&lt;/p&gt;&#xA;&lt;p&gt;As far as maintenance is concerned, airliners go &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_maintenance_checks&quot; rel=&quot;nofollow noreferrer&quot;&gt;500-800 hours&lt;/a&gt; between their low level A checks. However, they also undergo routine maintenance at each stop. Mechanical or electronic items that fail are replaced and minor checks are performed. Engines need oil, hydraulic systems need to be replenished.&lt;/p&gt;&#xA;&lt;p&gt;These are all decisions made as part of the aircraft design process. By making systems more robust, by adding capacity for consumables such as engine oil, these intervals can be extended. Materials such as composites that are less susceptible to corrosion or fatigue can be used. Electric motors need much less maintenance than jet or piston engines, and electricity can come from solar panels.&lt;/p&gt;&#xA;&lt;p&gt;It really just comes down to the design of a plane. Theoretically, an &amp;quot;indefinite&amp;quot; endurance is certainly possible. It would probably have to be unmanned, but with a robust structural and propulsion design, it could happen. However, everything will fail or wear out eventually, and without a crew or some system to replace components, that will be the limiting factor.&lt;/p&gt;&#xA;&lt;h3&gt;Examples&lt;/h3&gt;&#xA;&lt;p&gt;As far as commercial flights, there is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Non-stop_flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article&lt;/a&gt; that lists the longest scheduled flights by distance, aircraft type, and airline (and also the shortest scheduled flights, just because). The longest duration flight is DAL201, Johannesburg to Atlanta at 16 hours, 55 minutes on a 777-200LR (currently the airliner with the longest range).&lt;/p&gt;&#xA;&lt;p&gt;With aerial refueling, endurance increases. The B-2 has flown missions of &lt;a href=&quot;http://www.dailymail.co.uk/news/article-1368337/Libya-crisis-B2-stealth-bombers-25-hour-flight-Missouri-Tripoli.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;at least 25 hours&lt;/a&gt;, with a crew of 2. Landing for a fuel stop (but without engine shutdown), the longest mission is &lt;a href=&quot;http://air-attack.com/page/36/B-2-Spirit.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;44 hours&lt;/a&gt;. The longest training mission ever was &lt;a href=&quot;http://www.globalsecurity.org/wmd/systems/b-2-ops.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;50 hours&lt;/a&gt;. The pilots train extensively in order to be able to fly these missions.&lt;/p&gt;&#xA;&lt;p&gt;The B-52 has a similar mission and has flown missions as long as &lt;a href=&quot;http://www.airforcemag.com/magazinearchive/pages/1992/march%201992/0392stealth.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;35 hours&lt;/a&gt;. Despite being a single seat aircraft, the F-117 has made flights of over &lt;a href=&quot;http://www.f117sfa.org/sfa_newsletter/Newsletter2012-12.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;18 hours&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Also notable is the Rutan Voyager, first plane to fly nonstop around the world. The crew of 2 took &lt;a href=&quot;http://en.wikipedia.org/wiki/Rutan_Voyager&quot; rel=&quot;nofollow noreferrer&quot;&gt;9 days&lt;/a&gt; to accomplish this.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Solar_Impulse_Project&quot; rel=&quot;nofollow noreferrer&quot;&gt;Solar Impulse&lt;/a&gt; plane is currently in development, and has made a flight of 26 hours with 1 pilot.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-28T17:43:44.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2780" PostTypeId="2" ParentId="2761" CreationDate="2014-03-26T20:13:44.283" Score="1" Body="&lt;p&gt;The problem with a gun is that if staff are the terrorists then everything becomes that much more dangerous.&lt;br&gt;&#xA;In some cases such as FedEx hijacking, and other ones, the chance of the hijacking being an inside job is higher. Therefore it was much more easier to overpower one hijacker who wanted to assault crew physically, than it would be if he were carrying a gun.&lt;br&gt;&#xA;Guns usually make things much much worse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Even if the pilot has a gun. It still gives opportunity for the hijacker to snatch the gun. Pilots are usually busy flying the plane rather than constantly inspecting who is behind them and having a gun on the ready. And if the flight is a long one and pilot retrieves into the bed to sleep then likelihood of having the gun snatched is even higher. And if you look at some hijackings, the hijacker usually has the jump on the victims, so him obtaining a gun would not be too difficult. &lt;/p&gt;&#xA;" OwnerUserId="1839" LastEditorUserId="1839" LastEditDate="2014-03-26T21:32:36.260" LastActivityDate="2014-03-26T21:32:36.260" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2782" PostTypeId="2" ParentId="544" CreationDate="2014-03-26T21:05:15.930" Score="7" Body="&lt;p&gt;Wing sweep, incidence, and airfoil geometry will all have to be adjusted to achieve the best performance at a certain air speed, density, and Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The software that &lt;a href=&quot;https://aviation.stackexchange.com/a/546/1696&quot;&gt;egid mentioned&lt;/a&gt; is a good place to start. While studying aerospace in college, XFOIL was used for basic airfoil analysis in our classes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another program used was &lt;a href=&quot;http://web.mit.edu/drela/Public/web/avl/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AVL&lt;/a&gt;. This analyzes the aircraft as a whole and can model other things such as dynamic stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm glad that XPlane was also mentioned, even though I wouldn't consider it the most scientific tool for testing wing geometry. It is an interesting way to test configurations since it does use the airplane geometry to simulate the performance characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to consider more variables such as sweep, dihedral, and different airfoils over the wingspan, computational fluid dynamics (CFD) software is used. ANSYS Fluent is one example. There are many other packages out there, and anyone doing serious commercial airfoil design will have proprietary software and methods for this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, even in the days of supercomputers and CFD, wind tunnel testing is still very important. Scale models can be tested to validate the computer models and demonstrate performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as requirements, they can get very complicated. For aircraft, of course, the primary goal is to provide the lowest drag at cruise conditions. However, many other factors include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Preventing &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroelasticity&quot; rel=&quot;nofollow noreferrer&quot;&gt;flutter&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Provide room for sufficient supporting structure&lt;/li&gt;&#xA;&lt;li&gt;Provide room for fuel &lt;/li&gt;&#xA;&lt;li&gt;Methods to manufacture the shape&lt;/li&gt;&#xA;&lt;li&gt;Good stall characteristics&lt;/li&gt;&#xA;&lt;li&gt;No bad aerodynamics with fuselage and engines&lt;/li&gt;&#xA;&lt;li&gt;Enough lift with flaps for low landing speed&lt;/li&gt;&#xA;&lt;li&gt;Able to accommodate flaps, slats, spoilers, and ailerons&lt;/li&gt;&#xA;&lt;li&gt;Tip treatment like winglets/raked tips&lt;/li&gt;&#xA;&lt;li&gt;Wingspan must fit into available space (airport, hangar, aircraft carrier, etc.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And probably many more. Of course, the air speed and conditions will also affect the fuselage, empennage (tail) and its control surfaces, and engines, so this will also be taken into account.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-04-09T14:30:11.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2783" PostTypeId="2" ParentId="544" CreationDate="2014-03-26T21:50:44.170" Score="2" Body="&lt;p&gt;For a recent design task involving reflex aerofoils we tried to get some data out of &lt;a href=&quot;http://www.mh-aerotools.de/airfoils/javafoil.htm&quot; rel=&quot;nofollow&quot;&gt;this program&lt;/a&gt; from www.mh-aerotools.de. There's both an applet and download, I wasn't able to run the applet but the download is decently extensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your problem however is probably that any decently-sized aircraft manufacturer will have their own proprietary CFD software for the purpose and skilled programmers and aeronautical engineers to go with it.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1961" LastEditDate="2014-06-23T21:53:55.007" LastActivityDate="2014-06-23T21:53:55.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2784" PostTypeId="2" ParentId="2773" CreationDate="2014-03-26T22:36:48.503" Score="13" Body="&lt;p&gt;It will not work in EASA for a variety of reasons. Of the top of my head:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Like Lnafziger mentioned, you will need to do at least 10 hours solo. Most jet engines (but the smallest such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Diamond_D-Jet&quot; rel=&quot;noreferrer&quot;&gt;D-Jet&lt;/a&gt;) have a minimum required crew of two. Also, you are not allowed to switch airplanes in the PPL course (ie. fly solo with one airplane and dual with another see FCL.235) so you are stuck.&lt;/li&gt;&#xA;&lt;li&gt;Most jet aircraft (and as far as I know all commercial ones) are multi-engine. You will need 70 hours PIC before you can receive instruction on multi-engine, and you cannot fly PIC before you have your PPL.&lt;/li&gt;&#xA;&lt;li&gt;Multi-engine jet aircraft require a type rating, which has a lot of license pre-requisites before you are even allowed to enter the cabin: MCC, IR, MEP(land)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;There are a few prerequisites specified in  &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2011:311:0001:0193:EN:PDF&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;Part-FCL&lt;/strong&gt;&lt;/a&gt; about getting your first class or type rating, and to accomplish most of them you will need to have at least a PPL (eg IR(A), ATPL theory tests, hours PIC ,etc)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;FCL.235 Skill test&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(b) An applicant for the skill test shall have received flight instruction on the same&#xA;class or type of aircraft, or a group of balloons to be used for the skill test.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;FCL.720.A Experience requirements and prerequisites for the issue of&#xA;class or type ratings — aeroplanes&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Unless otherwise determined in the&#xA;operational suitability data established in accordance with Part-21,&#xA;an applicant for a  class or type rating shall comply with the&#xA;following experience requirements and prerequisites for the issue of&#xA;the relevant  rating:&lt;/p&gt;&#xA;&lt;p&gt;(a) &lt;strong&gt;Single-pilot multi-engine&lt;/strong&gt; aeroplanes. An&#xA;applicant for a first class or type rating on a single-pilot&#xA;multi-engine  aeroplane shall have completed at least &lt;strong&gt;70 hours as PIC&lt;/strong&gt;&#xA;on aeroplanes.&lt;/p&gt;&#xA;&lt;p&gt;(b) &lt;strong&gt;Single-pilot&lt;/strong&gt; high performance &lt;strong&gt;non-complex aeroplanes&lt;/strong&gt;. Before starting flight training, &amp;gt; an applicant for a first class or&#xA;type rating for a single-pilot aeroplane classified as a high performance aeroplane shall:&lt;/p&gt;&#xA;&lt;p&gt;(1) have at least &lt;strong&gt;200 hours of total flying&lt;/strong&gt; experience, of which &lt;strong&gt;70 hours as PIC&lt;/strong&gt; on aeroplanes; and&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;(c) &lt;strong&gt;Single-pilot&lt;/strong&gt; high performance &lt;strong&gt;complex aeroplanes&lt;/strong&gt;.&#xA;Applicants for the issue of a first type rating for a complex single-&#xA;pilot aeroplane classified as a high performance aeroplane shall, in&#xA;addition to meeting the requirements of (b), have  fulfilled the&#xA;requirements for &lt;strong&gt;a multi-engine IR(A)&lt;/strong&gt;, as established in Subpart G.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;(d) &lt;strong&gt;Multi-pilot aeroplanes&lt;/strong&gt; [...] or comply with the following&#xA;requirements:&lt;/p&gt;&#xA;&lt;p&gt;(1) have at least &lt;strong&gt;70 hours of flight experience as PIC&lt;/strong&gt;&#xA;on aeroplanes;&lt;/p&gt;&#xA;&lt;p&gt;(2) hold &lt;strong&gt;a multi-engine IR(A)&lt;/strong&gt;;&lt;/p&gt;&#xA;&lt;p&gt;(3) have passed the&#xA;&lt;strong&gt;ATPL(A) theoretical knowledge&lt;/strong&gt; examinations in accordance with this&#xA;Part; and  [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="419" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-27T11:07:57.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2785" PostTypeId="1" AcceptedAnswerId="2795" CreationDate="2014-03-26T22:48:35.523" Score="12" ViewCount="4719" Body="&lt;p&gt;Currently in my mid-'30s, I can still clearly remember the time when half of the plane's passengers were smoking throughout a long-haul flight. I know commercial flights became non-smoking sometime in the late '90s but I can't remember the exact timeline and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Inflight_smoking&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia article&lt;/a&gt; is remarkably lean in details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When did the major airlines start forbidding inflight smoking? How long did it take for the new policy to spread across most of the airlines? Can we expect this length of transition period to apply to other significant policy changes (e.g. the use of small electronic devices being allowed during take-off and landing by some airlines, provided they are in flight-safe mode)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uVjUp.png&quot; alt=&quot;http://www.theage.com.au/national/qantas-to-sell-cigarettes-on-overseas-flights-20080716-3gcw.html&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="97" LastEditDate="2014-03-27T12:57:40.903" LastActivityDate="2014-03-27T12:57:40.903" Title="When did inflight smoking become (widely) prohibited?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2786" PostTypeId="1" AcceptedAnswerId="2789" CreationDate="2014-03-26T22:59:02.890" Score="12" ViewCount="6565" Body="&lt;p&gt;If I understand correctly, when a plane transitions from takeoff roll to being airborne, it is not something that happens &quot;by itself&quot; when the airspeed is high enough, but is caused by deliberate pilot input somehow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which control surfaces are involved in causing the plane to lift off?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it an ordinary nose-up movement of the elevators? That is, the elevators create negative lift that pushes the tailplane &lt;em&gt;down&lt;/em&gt;, which makes the entire aircraft pivot around the main gear and increases the wings' AoA enough to create lift that takes the plane off the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Or is it something that increases lift with unchanged attitude, such as a symmetric aileron movement, or an additional flaps extension? And then &lt;em&gt;after&lt;/em&gt; the plane is airborne it is rotated to climbing attitude?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The descriptions I can easily Google up point towards 1. However, while that makes perfect sense for tricycle gear I don't see how that would work with taildraggers. Pushing down on the tail would just increase the downward force on the tail wheel rather than change the AoA.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="97" LastEditDate="2014-03-27T12:56:14.670" LastActivityDate="2019-01-08T22:23:49.730" Title="What is the immediate cause of liftoff?" Tags="&lt;takeoff&gt;&lt;attitude&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2787" PostTypeId="2" ParentId="2786" CreationDate="2014-03-26T23:04:42.520" Score="11" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;As the elevators rotate to get a negative pitch angle to the horizontal (moving the tip of the elevator upwards), a pressure difference is created causing it to produce a downwards force, and as a result the aircraft pivots around the landing gear, rotating upwards.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As it does so, the wing starts to generate more lift, as can be&#xA;seen on the graph below. The higher the angle of attack- the more&#xA;lift, since the lift coefficient becomes higher, up to where stall starts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When the lift exceeds the weight, the aircraft will lift off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Lift_curve.svg/500px-Lift_curve.svg.png&quot; alt=&quot;lift&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For taildraggers&lt;/strong&gt;, the tail is normally rotated up at a low speed while the aircraft continues to accelerate, and once a sufficient speed is reached, the tail surface is again lowered, causing the wing to increase the AoA and to lift. &lt;em&gt;Footnote: If I'm not mistaken, this is more of an act to improve control and reduce drag, since at some point the aircraft will lift off on it's own with it's tail-down angle of attack.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dyN3m.jpg&quot; alt=&quot;taildragger&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-08T22:23:49.730" LastActivityDate="2019-01-08T22:23:49.730" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="2788" PostTypeId="2" ParentId="2786" CreationDate="2014-03-26T23:06:43.093" Score="1" Body="&lt;p&gt;I can't answer for tail-draggers, but this is how it works for a tricycle landing gear.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Initiate takeoff roll&lt;/strong&gt; - power is applied&lt;/li&gt;&#xA;&lt;li&gt;$V_1$ - At this point, the pilot must proceed with takeoff, even in event of an engine failure.&lt;/li&gt;&#xA;&lt;li&gt;$V_R$ &lt;strong&gt;(Rotate)&lt;/strong&gt; - at this point, the pilot pulls back on the stick, causing the aircraft to pitch up, rotating on the main gear.&lt;/li&gt;&#xA;&lt;li&gt;$V_2$ - Rotate at this speed in event of an engine failure.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Also, if you keep accelerating down the runway, at some point you will have so much lift that the plane will take itself off.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-04-16T23:54:24.193" LastActivityDate="2014-04-16T23:54:24.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2789" PostTypeId="2" ParentId="2786" CreationDate="2014-03-26T23:07:31.777" Score="10" Body="&lt;p&gt;The answer is indeed (a). For tailwheel aircraft, what typically happens is typically the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;With all 3 wheels on the ground, you start gaining speed by increasing thrust.&lt;/li&gt;&#xA;&lt;li&gt;Very soon (e.g. much sooner that the minimum take-off speed), you push the stick to lift the tailwheel off the ground and put the aircraft at more or less zero AoA.&lt;/li&gt;&#xA;&lt;li&gt;When you reach the rotate speed, you pull to increase the AoA and to lift off (as with tricycles). The required pitch up angle is much smaller than what would be needed for the tail wheel to touch the ground again.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Alternatively, you may keep the tailwheel on the ground all the way until liftoff. Since with the tailwheel on the ground your AoA is positive, you just need to reach enough speed to generate the required lift for take-off. This may not be possible with all tailwheel aircraft or may increase take-off run length, though.&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="94" LastEditDate="2014-03-26T23:11:44.813" LastActivityDate="2014-03-26T23:11:44.813" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2790" PostTypeId="2" ParentId="2786" CreationDate="2014-03-26T23:10:19.437" Score="3" Body="&lt;p&gt;When you take off in a tail dragger, you let the tail rise so you’re only on the main gear as you accelerate. Then, when you want to take off, you use normal elevator movements to increase the angle of attack. Yes, the tail will fall slightly when this happens. Increased angle of attack means more lift, so you take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you hypothetically held the tail wheel on the ground with the elevator, the main wheels could, for a theoretical plane, lift off with the tail wheel still on the ground. But in reality, the main wing would be eventually generating more lift than the tail and so the plane would rise into the air.&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2014-03-26T23:10:19.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2791" PostTypeId="1" AcceptedAnswerId="2793" CreationDate="2014-03-27T00:59:31.653" Score="11" ViewCount="4733" Body="&lt;p&gt;I was looking at potential experimental projects when I read &lt;a href=&quot;http://www.cricri.zoomshare.com/&quot; rel=&quot;noreferrer&quot;&gt;this fascinating website&lt;/a&gt; about a tiny aerobatic-capable twin-engine airplane. It's light enough to be an ultralight, but much too fast:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dusls.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from the obvious fun of flying this little plane, I wondered whether:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I'd be able to log time in the Cri-Cri as multi-time? My guess is yes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Assuming I'm MEL-IFR, could I log multi-IFR with a two-way radio, altimeter, Dynon-type AI, HI and at least one cert. VOR &amp;amp; glide slope? An approach cert. GPS setup would be too heavy I assume. My guess is this is wishful thinking...&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1750" LastEditorUserId="65" LastEditDate="2015-02-26T16:06:57.227" LastActivityDate="2019-12-03T09:46:36.457" Title="Can I log time in a Cri-Cri twin-engine aircraft?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;multi-engine&gt;&lt;amateur-experimental&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2792" PostTypeId="2" ParentId="2791" CreationDate="2014-03-27T02:00:17.857" Score="7" Body="&lt;p&gt;Yep, as long as your avionics are certified and you follow all the rules for experimental aircraft in IFR you can log it. It's questionable whether or not anyone would accept the time when you go to get a job, but they might.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would imagine that you're right about the avionics weight, although glass might actually reduce the weight.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-03-27T02:00:17.857" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2793" PostTypeId="2" ParentId="2791" CreationDate="2014-03-27T02:15:48.850" Score="11" Body="&lt;p&gt;What a positively &lt;em&gt;delightful&lt;/em&gt; looking aircraft!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see no reason you couldn't log time in this as multi-engine time - it clearly has two engines, with two separate sets of controls (at least throttles, from what I can see).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly I see no reason you couldn't fly it IFR as an experimental aircraft, provided it's &quot;properly equipped&quot; (consult the FARs for all the details on what you need), passes an IFR pitot/static test, and has appropriate radios (Transponder which you'd likely need anyway, Com, and Nav).&lt;br&gt;&#xA;Whether you'd want to take it up in real weather is another matter though :-) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For that matter if you want GPS you could certainly have it without much weight penalty: throw in a Garmin GNS 430W and cover the Nav/Com and GPS in one ~7-8lb box.  Whether or not that kind of investment in what's basically a single-seat super-ultralight is &quot;worth it&quot; is a judgment call only you could make, but it definitely seems possible.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-27T02:15:48.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2794" PostTypeId="1" AcceptedAnswerId="2811" CreationDate="2014-03-27T02:31:30.003" Score="9" ViewCount="2693" Body="&lt;p&gt;In the case of flight MH370, I think passengers on board would have long enough time to realise that something is wrong with their flight. I have a habit of carrying a compass with me when I travel abroad. If the plane is not heading in the general direction towards its destination once it reaches cruising altitude, then I would be worried. This is especially so for passengers on board flight MH370 when it appears that it is flying in the opposite direction for a very long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can a passenger do if he realises that the plane is not flying in the right path, i.e. a possible suicide mission or hijack?&lt;/p&gt;&#xA;" OwnerUserId="1390" LastEditorUserId="22550" LastEditDate="2018-11-24T14:36:53.950" LastActivityDate="2018-11-24T14:36:53.950" Title="What can passengers do if they realise their plane is not on the right path?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;passenger&gt;&lt;mh370-incident&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2795" PostTypeId="2" ParentId="2785" CreationDate="2014-03-27T02:39:41.943" Score="8" Body="&lt;p&gt;There is an interesting timeline &lt;a href=&quot;http://no-smoke.org/document.php?id=334&quot;&gt;here&lt;/a&gt; which includes other transportation service as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this &lt;a href=&quot;http://www.nytimes.com/1988/04/12/us/faa-details-rules-of-smoking-ban-in-air.html&quot;&gt;New York Times article&lt;/a&gt;, the FAA banned smoking on all flights under 2 hours beginning April 23, 1988. According to the timeline, Northwest and British Airways make all domestic service smoke free shortly after.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On February 25th, 1990, the rule is expanded to all domestic flights under 6 hours, which includes all but 28 of 16,000 flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1992, ICAO urges its members to go smoke free by July 1, 1996. Delta went smoke free on all flights starting in 1995. TWA, United, and American follow suit in 1997. In 1998 even more airlines go smoke free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.federalregister.gov/articles/2000/06/09/00-14480/smoking-aboard-aircraft&quot;&gt;federal rule&lt;/a&gt; bans smoking on all flights to and from the US and is effective June 4, 2000. It mentions that all domestic and 98% of international flights were already in compliance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;td;dr The FAA banned smoking on all flights under 2 hours in 1988, and it escalated from there. Within 10 years, almost all airlines were smoke free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that smoking had the advantage of being a health issue, whereas electronic devices are more just convenience and comfort. Barring any emergent safety issues, it seems easier to allow people to do something new (use electronic devices) than stop them from doing something (smoking). Considering the proliferation and advancement of inflight entertainment systems, I would expect airlines to be fairly quick about allowing the use of devices, especially since some already do (I know American and United do).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-27T02:39:41.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2796" PostTypeId="1" CreationDate="2014-03-27T03:36:43.543" Score="12" ViewCount="762" Body="&lt;p&gt;Do lighter-than-air aircraft communicate with ATC? If not, how do they avoid running into other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-03-27T04:09:30.167" LastActivityDate="2014-03-28T01:27:11.320" Title="Do lighter-than-air aircraft communicate with ATC?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;lighter-than-air&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2797" PostTypeId="2" ParentId="2726" CreationDate="2014-03-27T03:43:35.883" Score="7" Body="&lt;p&gt;You actually have some pretty good hypothesis here!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To start with, it truly is &quot;a simple engineering matter to attach the wings to the body at an angle such that the right angle of attack for cruise flight corresponded to the body being horizontal&quot;, but you missed the design goals slightly.  This angle is called the angle of incidence, or the rigging angle of the wing and is the difference between the fuselage angle and the wing angle.  This is a very specific angle that is calculated as part of the design of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dfjJ0.png&quot; alt=&quot;angle of incidence example&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The wing incidence must satisfy the following design requirements: &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The wing must be able to generate the desired lift coefficient during cruising flight. &lt;/li&gt;&#xA;  &lt;li&gt;The wing must produce minimum drag during cruising flight. &lt;/li&gt;&#xA;  &lt;li&gt;The wing setting angle must be such that the wing angle of attack could be safely varied (in fact increased) during take-off operation. &lt;/li&gt;&#xA;  &lt;li&gt;The wing setting angle must be such that the fuselage generates minimum drag during  cruising flight (i.e. the fuselage angle of&#xA;  attack must be zero in cruise).    &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;These design requirements naturally&#xA;  match with the wing airfoil angle of attack  corresponding to the&#xA;  airfoil ideal lift coefficient (see figure 5.26).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The typical number for wing incidence for majority of aircraft is&#xA;  between 0 to 4 degrees.  As a general guidance, the wing setting angle&#xA;  in supersonic fighters, is between 0 to 1 degrees; in GA aircraft,&#xA;  between 2 to 4 degrees; and in jet transport aircraft is between 3 to&#xA;  5 degrees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notice that the proper angle of incidence will have the wing at its most efficient during cruise while the fuselage also generates the minimum amount of drag.  Both of these are calculated independently and the angle of incidence is set so that both conditions are satisfied at the same time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft design decisions are usually a compromise between different, many times conflicting goals.  He goes on to say that it may be adjusted from the optimum in some cases:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The wing setting angle may be modified as the design process&#xA;  progresses. For instance, a  fuselage with large unsweep over the rear&#xA;  portion to accept aft cargo doors may have their minimum drag at a&#xA;  small positive angle of attack. In such cases, the wing incidence will&#xA;  be reduced accordingly. Another, les fundamental, consideration is&#xA;  that stopping performance during landing operation to get as much&#xA;  weight on the braked wheels as possible. Thus, there is a benefit to&#xA;  reduce the wing incidence slightly to the extent that the change is&#xA;  not felt significantly in the cabin. Reducing the nose gear length&#xA;  will do the same thing. This technique is limited in passenger&#xA;  aircraft because a level cabin floor is desirable on the ground. But,&#xA;  for fighter aircraft, the level floor is not a design consideration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another possible reason to adjust the angle of incidence to a non-optimum number is to ensure that when landing the aircraft the nose is not pitched down, in order to avoid a higher likelihood of hitting the nosewheel first on landing.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Most of the material for this answer came from &lt;a href=&quot;http://faculty.dwc.edu/sadraey/Chapter%205.%20Wing%20Design.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt; written by Mohammad Sadraey at Daniel Webster College &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-27T04:14:12.967" LastActivityDate="2014-03-27T04:14:12.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2798" PostTypeId="2" ParentId="2796" CreationDate="2014-03-27T03:53:10.617" Score="13" Body="&lt;h1&gt;Short Version:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;No aircraft is required to talk to ATC, except in certain situations.  Whether or not they have a radio, all pilots are required to continuously watch outside the airplane for other aircraft and to avoid them visually, much like someone driving a car avoids other cars by looking for them.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Long Version:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Aircraft are required to communicate with ATC only in certain situations.  &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=069887a24b6c23dd0133e8ca5de91277&amp;amp;n=14y2.0.1.3.10&amp;amp;r=PART&amp;amp;ty=HTML&quot;&gt;14 CFR 91&lt;/a&gt; contains the requirements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;91.126 - Within 4 miles and 2,500 ft of an airport in Class G Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.127 - Within 4 miles and 2,500 ft of an airport in Class E Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.129 - Within Class D Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.130 - Within Class C Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.131 - Within Class B Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.135 - Within Class A Airspace&lt;/li&gt;&#xA;&lt;li&gt;91.155 - In weather conditions less than VFR&lt;/li&gt;&#xA;&lt;li&gt;91.183 - While operating IFR&lt;/li&gt;&#xA;&lt;li&gt;91.511 - More than 1 hour flight time or 100 miles from shore (overwater)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Many of these can be  waived with prior coordination with ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of the above situations, no radio is required.  In fact, there are still many airplanes that don't even have an electrical system, much less a radio, and they are perfectly legal to go fly around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if they &lt;strong&gt;do&lt;/strong&gt; have a radio (even a hand-held radio) it can greatly add to the safety of flight if they remain in contact with ATC since they can point out traffic that they might not have seen as quickly otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, whether or not the pilot is talking to ATC, they are required to &quot;see and avoid&quot; other aircraft, and certain aircraft have the right of way over other aircraft.  As you can imagine, an unpowered balloon can't really get out of way of a 747, so it is the responsibility of the more maneuverable aircraft to turn to avoid hitting the less maneuverable one (see 91.113 for more details).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also required to remain a certain distance away from clouds (91.155).  This is so that one aircraft doesn't come out of a cloud, possibly at a very high speed, and run right into another aircraft because they didn't have time to avoid them.  If they are far enough away, then the pilots will have time to see and avoid each other.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-28T01:27:11.320" LastActivityDate="2014-03-28T01:27:11.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2799" PostTypeId="2" ParentId="2382" CreationDate="2014-03-27T05:50:31.460" Score="5" Body="&lt;p&gt;Neither the FDR CB nor the CVR CB are accessible from the B772 flight deck.  The FDR is powered on at engine start. In the event of a mishap the CVR CB is pulled as a means of saving the data.  The CVR CB is accessed from the E&amp;amp;E bay.&lt;/p&gt;&#xA;" OwnerUserId="1846" LastEditorUserId="1846" LastEditDate="2014-03-27T06:07:34.693" LastActivityDate="2014-03-27T06:07:34.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2802" PostTypeId="1" CreationDate="2014-03-27T08:12:10.383" Score="0" ViewCount="115" Body="&lt;p&gt;I understand the rationale for putting seat backs straight, folding tables, fastening seatbelts etc., but I've never really understood why the window blinds matter.&lt;/p&gt;&#xA;" OwnerUserId="1850" LastActivityDate="2014-03-27T08:38:33.657" Title="Why do you have to put the blinds up during take off and landing?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-03-27T08:46:23.183" ContentLicense="CC BY-SA 3.0" />
  <row Id="2803" PostTypeId="1" CreationDate="2014-03-27T08:26:42.813" Score="22" ViewCount="5875" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2328/1850&quot;&gt;One seemingly plausible theory&lt;/a&gt; about the MH370 disappearance is that one or other of the pilots locked the other one out of the cockpit and then depressurised the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;https://aviation.stackexchange.com/a/2169/1850&quot;&gt;this answer&lt;/a&gt; mentions a code that can be entered to unlock the cockpit door. Could this apply in this case (on a 777)?&lt;/p&gt;&#xA;" OwnerUserId="1850" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-26T05:57:51.037" Title="Can one pilot lock the other out of the cockpit?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;boeing&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2804" PostTypeId="2" ParentId="2803" CreationDate="2014-03-27T08:33:53.127" Score="23" Body="&lt;p&gt;Yes, see the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_702&quot;&gt;Ethiopian Airlines hijacking&lt;/a&gt; in February 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.bbc.com/news/magazine-26671224&quot;&gt;this BBC article&lt;/a&gt; about MH370:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The security of the cockpit door offers protection against intruders, but it also prevents action being taken if something does go wrong. Last month the co-pilot of an Ethiopian Airlines flight waited for the pilot to go to the toilet before hijacking the aircraft and flying it to Switzerland. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for higher authority codes, from the same answer you linked to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Even if the stronger code is entered that will open the door the pilots still have some time to cancel the unlock request.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Meaning that if a pilot is willfully locking the other out of the cockpit, there is no way for the other to regain access to the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-03-27T15:28:01.887" LastActivityDate="2014-03-27T15:28:01.887" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2806" PostTypeId="1" AcceptedAnswerId="2813" CreationDate="2014-03-27T11:37:40.520" Score="41" ViewCount="85663" Body="&lt;p&gt;According to &lt;strong&gt;FAA regulations&lt;/strong&gt;, how far should a commercial jet be away from another plane in-flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xz3sD.jpg&quot; alt=&quot;commercial jet img&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about military planes? They get really close when in formations... Is there a minimum distance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jd5j2.gif&quot; alt=&quot;Military formation img&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="14897" LastEditDate="2019-06-17T22:59:39.120" LastActivityDate="2019-10-18T16:06:42.890" Title="How much is the minimum safe distance between two planes in-flight?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;air-traffic-control&gt;&lt;separation&gt;&lt;flying-in-formation&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2807" PostTypeId="2" ParentId="2794" CreationDate="2014-03-27T11:44:02.473" Score="4" Body="&lt;p&gt;Not only do most people have no clue about that direction they're supposed to be flying, the number of people alerting the crew of &quot;wrong directions&quot; from those that do and get nervous when the plane diverts to avoid a thunderstorm or simply switches to another airway that diverts from the direct course would quickly make the crew ignore any and all such comments from passengers.&lt;br/&gt;&#xA;Which is no doubt one of the reasons they don't like passengers using handheld GPS devices (quite apart from the blanket ban on anything that has an antenna).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-03-27T11:44:02.473" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2808" PostTypeId="2" ParentId="2806" CreationDate="2014-03-27T11:48:14.613" Score="6" Body="&lt;p&gt;With formation flights it is as close as the pilots feel comfortable with in the circumstances. On clear days and in level flight brushing wingtips is allowed as long as you don't endanger the other planes (which actual brushing would do).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For normal (commercial) flights vertical separation of 1000 feet is maintained when passing each other. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;for planes incoming for landing there is &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake_turbulence#Hazard_avoidance&quot; rel=&quot;nofollow noreferrer&quot;&gt;4-8 NM radar separation&lt;/a&gt; depending on the size and weight of the planes.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2018-12-12T02:02:21.670" LastActivityDate="2018-12-12T02:02:21.670" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="2809" PostTypeId="2" ParentId="2806" CreationDate="2014-03-27T11:48:36.397" Score="8" Body="&lt;p&gt;you have 3 separations for commercial flights&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;vertical separation&lt;/strong&gt;: two aircrafts flying in the same direction will be separated by 2 flight levels (FLs), equivalent to 2000 ft. The intermediate FL is occupied by planes flying in the opposite direction. Each aircraft has thus 500 ft above and below the assigned altitude of free airspace.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;lateral separation&lt;/strong&gt;: the airways are defined as being 10 nautical miles wide, 5 for each side&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;longitudinal separation&lt;/strong&gt;: I have no detailed information on this for the cruise, I hope someone else can fill the gap. During approach it depends on the size of the preceding aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-03-27T11:48:36.397" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2811" PostTypeId="2" ParentId="2794" CreationDate="2014-03-27T13:21:51.983" Score="15" Body="&lt;p&gt;Okay, so, going with the idea that you have a compass (and also with the idea that this can be a general question, not necessarily about flight MH370).  If you're heading from Tokyo, Japan to Seattle, Washington, USA (direct), then you could be reasonably certain the craft should be somewhere between headings 45 and 135.  So if you notice the craft is on a heading of 270 (ie., clearly you're going in the opposite direction) and this direction has been sustained for say, an hour, I'd think it would be okay to at least &lt;em&gt;ask&lt;/em&gt; the cabin crew what's going on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with any time you are raising a concern with the cabin crew, you should be polite.  As has been stated, they are used to passengers being a bit nervous and, as a result, they can easily interpret belligerence as a sign of irrational fear.  And, as you might guess, it's easy to ignore someone if you feel they are being irrational.  So, if you want be taken seriously, be polite.  You're far more likely to get an actual answer, or raise a valid concern even.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if you just ask, &quot;why are we headed west instead of east&quot; they may have a very simple answer like, &quot;well, the pilot mentioned we might have to take an odd route to avoid some weather&quot; or &quot;this is the flight to Bombay India, how did you get on it?&quot;  Or, they may have no idea and be concerned themselves, so they go and ask their superior.  Thus, goal achieved, you've alerted the flight crew :).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, so long as you're polite and don't become insistent (or belligerent) that you are correct, I can't see any harm in just asking.  And sometimes asking is what leads to a problem being solved so...  I'd say go for it.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-03-27T16:33:55.303" LastActivityDate="2014-03-27T16:33:55.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2812" PostTypeId="2" ParentId="2794" CreationDate="2014-03-27T13:52:24.710" Score="4" Body="&lt;p&gt;I concur with others that most passengers have no clue.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I flew from Toronto to Seoul.  The flight headed northeast, paralleled the east coast of Ellsmere Island with Greenland visible off the right side, then on into the Arctic, making land over Siberia somewhere, further over Ulan Bator, across China and into Seoul.  The north pole was always in the left hand semicircle RELATIVE BEARING.  This was all due to the winds aloft on that day.  This was always visible on the plane's installed in-flight information system.  Perfectly normal flight.  To a non-experienced aviator, this would seem like a nonsensical route possibly indicating a hijack situation, and fuel a lot of worry.  Cabin crew should respond to questions of course, but in most cases there is no cause to worry. So I too have a concern that a passenger having convinced him/herself that the plane is off course will do something to jeopardize the safety of the plane, crew, and passengers.   &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-03-27T15:14:15.537" LastActivityDate="2014-03-27T15:14:15.537" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2813" PostTypeId="2" ParentId="2806" CreationDate="2014-03-27T14:36:01.680" Score="54" Body="&lt;p&gt;The question specifically asks about FAA regulations, so I will try to provide specific citations.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Summary&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For a commercial airliner (as the question asked), separation will &lt;em&gt;usually&lt;/em&gt; be at least &lt;strong&gt;3 miles laterally&lt;/strong&gt;, &lt;em&gt;or&lt;/em&gt; &lt;strong&gt;1,000 feet vertically&lt;/strong&gt;. In the enroute environment -- at higher operating speeds above 10,000 feet and based on the type of Radar and distance from the antennae -- a &lt;strong&gt;5 mile&lt;/strong&gt; rule is applied laterally. This is true in &lt;em&gt;most but not all&lt;/em&gt; situations. There are exceptions: see below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also the &quot;or&quot;: it is allowed (and in fact rather common) for two jets to cross paths at the same moment, with one 1,000 feet directly above the other. The 3 miles is only required if the jets do not have at least 1,000 feet of vertical separation.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Pilots&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The regulations do not set a specific distance that pilots flying under VFR must maintain from each other. There's just the following blanket statement:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d2302efbd7d0368b9999a00eba1d3f0a&amp;amp;node=14:2.0.1.3.10.2.4.6&amp;amp;rgn=div8&quot;&gt;§91.111, Operating near other aircraft&lt;/a&gt;: (a) No person may operate an aircraft so close to another aircraft as to create a collision hazard. (b) No person may operate an aircraft in formation flight except by arrangement with the pilot in command of each aircraft in the formation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, there is the catch-all &quot;careless or reckless operation&quot; clause:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d2302efbd7d0368b9999a00eba1d3f0a&amp;amp;node=14:2.0.1.3.10.1.4.7&amp;amp;rgn=div8&quot;&gt;§91.13, Careless or reckless operation&lt;/a&gt;: No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots flying under IFR are subject to the same kinds of rules, and are still responsible for maintaining separation from other traffic when in visual conditions. The rules are the same: the pilot is given the discretion of deciding what a &quot;safe distance&quot; is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual distance limits only come into play for the air traffic controllers, who are responsible for providing minimum separation distances between IFR traffic.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Air Traffic Controllers&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The set of FAA regulations for air traffic controllers is &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/index.htm&quot;&gt;FAA order 7110.65&lt;/a&gt;. These regulations are quite complicated and there are lots of exceptions and corner cases for various scenario. I'll try to give only the most basic rules here, but note that a full reading of 7110.65 would be necessary to understand all the minutiae.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical separation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0405.html#atc0405.html.1&quot;&gt;4-5-1 Vertical Separation Minima&lt;/a&gt;. In general, 1,000 feet for IFR traffic (with exceptions).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0707.html#3oJ190JACK&quot;&gt;7-7-3 Separation&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0708.html#MpJ186JACK&quot;&gt;7-8-3 Separation&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0709.html#rpJ398JACK&quot;&gt;7-9-4 Separation&lt;/a&gt;. 500 feet for VFR aircraft (with exceptions).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Lateral separation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0505.html#PiK190JACK&quot;&gt;5-5-4 Minima&lt;/a&gt;. In general, 3 miles in the terminal environment and 5 miles in the enroute environment (with exceptions).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Things get more complicated in the following scenarios, and exceptions apply to them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Oceanic environment (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/TOC.html#Chapter%C2%A08.%20Offshore/Oceanic%20Procedures&quot;&gt;7110.65 Chapter 8&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Approach environment, especially at large/busy airports with parallel runways and special approach monitoring radar. (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/TOC.html#Chapter%C2%A03.%20Airport%20Traffic%20Control-%20Terminal&quot;&gt;7110.65 Chapter 3, Sections 9 &amp;amp; 10&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Nonradar environment (anytime the controller is not able to &quot;apply radar separation&quot;) (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/TOC.html#Chapter%C2%A06.%20Nonradar&quot;&gt;7110.65 Chapter 6&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For these scenarios the regulations are rather lengthy and complicated, so I would simply refer you to Order 7110.65 in general.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Military&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When flying in airspace controlled by ATC, military pilots must follow the same rules as civilian aircraft. ATC will keep them separated according to the rules above. However, there are two main exceptions to this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying in formation, such as for training, aerial refueling, or intercepting aircraft, they are much too close for ATC to provide safety. In these cases, ATC will allow the pilots to fly under MARSA (&lt;a href=&quot;http://en.wikipedia.org/wiki/MARSA_%28aviation%29&quot;&gt;Military Assumes Responsibility for Separation of Aircraft&lt;/a&gt;). In the case of interception, if the fighter pilot is not able to see the aircraft they are intercepting before the minimum separation, they must break off. They can only fly under MARSA if they can actually ensure visual separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA can also define an MOA (&lt;a href=&quot;http://en.wikipedia.org/wiki/Military_operations_area&quot;&gt;Military Operations Area&lt;/a&gt;). Once military aircraft enter this area, ATC is no longer responsible for them and they are under MARSA. When the aircraft leave the MOA, ATC resumes control. They can still be under MARSA for a formation, but ATC will keep that formation separated from other traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In tactical formation flying, there is no limit. The &lt;a href=&quot;http://www.blueangels.navy.mil/&quot;&gt;Blue Angels&lt;/a&gt; routinely fly with &lt;a href=&quot;http://www.blueangels.navy.mil/show/faq.aspx&quot;&gt;only 18&quot; separation between the wing tip and the cockpit canopy&lt;/a&gt;. Combat aircraft fly a variety of different formation patterns at varying distances, and pilots are extensively trained on each pattern and what the appropriate/safe distances are. (For example, a fingertip formation allows for much closer flying than a line-abreast formation.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="3504" LastEditDate="2014-12-09T00:07:32.070" LastActivityDate="2014-12-09T00:07:32.070" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="2814" PostTypeId="1" AcceptedAnswerId="2815" CreationDate="2014-03-27T15:23:30.770" Score="17" ViewCount="5958" Body="&lt;p&gt;Does an electronic database containing the various civil runways in a given region of the world exists?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe even categorized by type (e.g., grass vs asphalt), length, if controlled or not, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it does not exists, what would be the effort related to creating one?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/97/danny-beckett&quot;&gt;Danny Beckett&lt;/a&gt; mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/questions/2814/airfields-runways-database#comment5453_2814&quot;&gt;comments&lt;/a&gt;, &lt;a href=&quot;http://www.ourairports.com/data/&quot; rel=&quot;nofollow noreferrer&quot;&gt;OurAirports&lt;/a&gt; has such data, but there is a &quot;use at your own risk&quot; disclaimer. May any source be reliable and trustworthy or will I find such disclaimer on all sources?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2020-08-26T21:01:16.993" Title="Is there a database containing detailed information about airfields and runways?" Tags="&lt;airport&gt;&lt;runways&gt;&lt;datasets&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2815" PostTypeId="2" ParentId="2814" CreationDate="2014-03-27T15:47:45.150" Score="19" Body="&lt;p&gt;The FAA publishes the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/NASR_Subscription/&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASR&lt;/a&gt; database. This is an official, authoritative data set that covers all airports, airways, routes and navigation aids under FAA jurisdiction. The data files are not human-readable though and require special software to display.&lt;/p&gt;&#xA;&lt;p&gt;Other civil aviation authorities in other countries have similar products. Some are available for free, some are not. Many countries claim intellectual property rights on their data and it can be quite difficult to get at/use it.&lt;/p&gt;&#xA;&lt;p&gt;Some companies like &lt;a href=&quot;http://jeppdirect.jeppesen.com/legal/charts/ads-overview.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jeppesen&lt;/a&gt; do this collection for you: they have agreements with aviation authorities, obtain each authority's data sets (like the FAA's NASR linked above), and compile all of them into a single large database. This database is then reprocessed in forms usable by avionics like GPS receivers or Flight Management Systems (FMS). These countries charge a significant fee for this service, and there are licensing terms that limit your use of the data. The fee is substantial depending on the format you get the data in (up to thousands of dollars or more for FMS systems for large transport aircraft) and puts the dataset out of reach of a casual user.&lt;/p&gt;&#xA;&lt;p&gt;The U.S. Department of Defense publishes the &lt;a href=&quot;http://en.wikipedia.org/wiki/DAFIF&quot; rel=&quot;nofollow noreferrer&quot;&gt;DAFIF&lt;/a&gt; which is a similar compilation of worldwide data. This database used to be available publicly for free, but is now restricted to Department of Defense personnel (it is not classified but it is not available to the public).&lt;/p&gt;&#xA;&lt;p&gt;There are many websites based on one or more of the datasets above, but as noted in comments, these websites are not official or authoritative. They also generally have their own license terms that limit the way you can use the information and that prevent you from downloading the database in bulk. This all stems from the intellectual property claims made by many civil aviation authorities. It costs countries a lot of money to maintain the data and they want to be able to generate some revenue from it.&lt;/p&gt;&#xA;&lt;p&gt;So the bottom line is that for some regions like the United States, official data is readily and freely available; for other regions, not so much. (And among developed countries, the U.S. is the exception; most do not offer their data freely.) To get data for these other regions, or to create a global dataset, would involve a &lt;em&gt;lot&lt;/em&gt; of effort and money (beyond the reach of a normal individual). Companies that do this work for you charge hefty fees to provide the data to you.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="52160" LastEditDate="2020-08-26T21:01:16.993" LastActivityDate="2020-08-26T21:01:16.993" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2816" PostTypeId="1" CreationDate="2014-03-27T17:14:11.533" Score="19" ViewCount="810" Body="&lt;p&gt;&lt;a href=&quot;http://www.bbc.com/news/world-asia-20975601&quot; rel=&quot;noreferrer&quot;&gt;In January 2013&lt;/a&gt;, a python hitched a ride on plane, unfortunately exposed on the wing after getting sucked out of its hiding place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://info.flightmapper.net/flight/Qantas_QF_191&quot; rel=&quot;noreferrer&quot;&gt;Qantas 191&lt;/a&gt; is a Cairns → Port Moresby flight on a DHC-8-400, probably the first of the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having done walk-arounds for a Cherokee, I would like to think that I wouldn't allow such an event to happen on a small plane.  On the other hand, I realize that it would be impossible to do a thorough inspection on, say, an Airbus A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a typical preflight inspection checklist for a Dash 8 or similar plane?  Would it have included, for example, a visual inspection of the flaps that would have allowed the snake to have been spotted?&lt;/p&gt;&#xA;" OwnerUserId="487" LastEditorUserId="65" LastEditDate="2015-02-26T15:39:12.003" LastActivityDate="2015-08-03T13:26:40.617" Title="Should a pre-flight inspection spot snakes on a plane?" Tags="&lt;airline-operations&gt;&lt;preflight&gt;&lt;dash-8&gt;&lt;australia&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2817" PostTypeId="1" CreationDate="2014-03-27T17:28:09.890" Score="43" ViewCount="8687" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/907/1073&quot;&gt;Another answer&lt;/a&gt; pointed out that laser illumination of a cockpit may be considered an emergency, and that pilots may take evasive action when under laser illumination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is laser illumination considered an emergency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have any documented instances of laser illumination resulted in injury to or loss of crew, passengers, or plane?&lt;/p&gt;&#xA;" OwnerUserId="1073" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-12-20T00:36:51.537" Title="Why is laser illumation of a cockpit an emergency?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;laser-illumination&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2818" PostTypeId="2" ParentId="2817" CreationDate="2014-03-27T17:36:34.120" Score="13" Body="&lt;p&gt;Some of the cheap, powerful lasers available now are capable of &lt;strong&gt;&lt;a href=&quot;http://www.cnn.com/2014/02/12/us/pilots-laser-attacks/&quot;&gt;blinding pilots&lt;/a&gt;&lt;/strong&gt; and in some cases causing lasting injury. Even temporary blindness, however, is something I think any pilot would consider an emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fairly recent &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2467857/FBI-investigating-latest-laser-pointer-attacks-pilots-landing-LaGuardia-airport-incidents-rise-17-cent-New-York-area-airports-year.html&quot;&gt;Daily Mail article&lt;/a&gt; states that &quot;the FBI noted that several commercial pilots earlier this year suffered significant injuries including a burnt retina.&quot; There are over 4000 reported incidents a year, and the number is apparently increasing rapidly. It is now a federal crime that has at least in one case resulted in prison time. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-03-27T17:36:34.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2819" PostTypeId="2" ParentId="2817" CreationDate="2014-03-27T17:50:51.540" Score="12" Body="&lt;p&gt;You can legally buy lasers that are certainly able to damage someone's eyes. They come with laser warnings for a reason, and being lasers, the intensity does not decrease much with distance. People with more powerful lasers could do even more damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.laserpointersafety.com/laser-hazards_aircraft/laser-hazards_aircraft.html&quot;&gt;laser safety site&lt;/a&gt; has good info about the effects it has on the pilot and what can happen to you if you are caught doing this. Here is &lt;a href=&quot;http://abcnews.go.com/blogs/headlines/2012/07/jetblue-pilot-suffers-eye-injury-from-green-laser/&quot;&gt;another article&lt;/a&gt; where the pilot suffered injury.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Laser illumination has not been identified as a factor in any accidents involving loss of life so far, but considering how many happen and the fact that they happen more and more often, it is certainly a hazard to safety and cause for declaring emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although many people charged with this crime claim their intentions were not malicious, that is certainly not always the case. Police helicopters are often targets, and this &lt;a href=&quot;http://www.businessinsider.com/david-cenciotti-egyptian-helicopter-coated-in-green-lasers-2013-7&quot;&gt;recent incident&lt;/a&gt; in Egypt is a notable example.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-03-28T17:32:21.233" LastActivityDate="2014-03-28T17:32:21.233" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2820" PostTypeId="2" ParentId="2817" CreationDate="2014-03-27T17:54:10.413" Score="52" Body="&lt;p&gt;Let me posit a hypothetical game (&quot;Don't Try This at... well &lt;em&gt;Anywhere&lt;/em&gt;&quot;).&lt;br&gt;&#xA;It's simple - there are just 3 rules:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Give your friend a nice laser pointer and have them stand at the end of a road&lt;br&gt;&#xA;  A half-mile or so should be plenty.  &lt;/li&gt;&#xA;  &lt;li&gt;Get in your car at the other end of the road and drive toward your friend.  &lt;/li&gt;&#xA;  &lt;li&gt;Your friend's goal is to shine the laser in your eyes. Your goal is simple: try not to crash.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Clearly this is not a very safe game.&lt;br&gt;&#xA;It should be clear that playing the same game with aircraft is substantially less safe. Someone attempting to &quot;play&quot; without your consent certainly rises to the definition of &quot;emergency&quot; in my book.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you actually play this game you'll note that the laser isn't a neat pinpoint when it's shining at you.&lt;br&gt;&#xA;Between scratches in the aircraft's window and the way your eye perceives light the laser pointer can completely blind the victim - check out the examples in the graphic below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[&lt;img src=&quot;https://i.stack.imgur.com/0HtN4.gif&quot; alt=&quot;Laser Effects[1]&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To date I don't believe any accidents have been attributed to laser illumination, but it is well within the realm of possibility, and the upward trend in laser illuminations of aircraft means the likelihood of such an accident is also increasing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information check out &lt;a href=&quot;http://www.faa.gov/about/initiatives/lasers/&quot; rel=&quot;noreferrer&quot;&gt;the FAA's Laser Safety Initiative&lt;/a&gt; -- and particularly the video &lt;a href=&quot;http://www.faa.gov/about/initiatives/lasers/hazards/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.  &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-27T17:54:10.413" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2822" PostTypeId="1" AcceptedAnswerId="2823" CreationDate="2014-03-27T19:17:42.973" Score="19" ViewCount="3279" Body="&lt;p&gt;Somtimes planes can either &lt;a href=&quot;http://en.wikipedia.org/wiki/Lion_Air_Flight_904&quot;&gt;come up short&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_605&quot;&gt;overrun&lt;/a&gt; a runway, ending up in the water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some limit for how close a runway can be to the water? Does it factor into the runway safety area that is required to be clear of obstacles (i.e., is water an obstacle)? Is there any requirement for displaced thresholds near water?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am asking primarily about the US, but information about any other jurisdictions is welcome.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="19" LastEditDate="2014-10-08T13:49:02.993" LastActivityDate="2016-07-05T06:43:12.333" Title="Is there a limit of how close a runway can be to the water?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;&lt;easa-regulations&gt;&lt;casa-regulations&gt;&lt;dgca-india-regulations&gt;" AnswerCount="7" CommentCount="21" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2823" PostTypeId="2" ParentId="2822" CreationDate="2014-03-27T19:31:26.343" Score="22" Body="&lt;p&gt;FAA Advisory Circular (AC) &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5300_13A.pdf&quot;&gt;150/5300-13A&lt;/a&gt; covers &quot;standards and recommendations for airport design.&quot; It does not include any restrictions on proximity to bodies of water, but it does make the following &lt;em&gt;recommendation&lt;/em&gt; in paragraph 319(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is recommended that the entire RSA and RPZ be accessible to rescue and fire-fighting vehicles such that no part of the RSA or RPZ is more than 330 feet (100 m) from either an all-weather road or a paved operational surface. Where an airport is adjacent to a body of water where access by rescue personnel from airport property is desirable, it is recommended that boat launch ramps with appropriate access roads be provided.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The actual FARs (&lt;a href=&quot;http://www.faa.gov/airports/airport_safety/part139_cert/&quot;&gt;14 CFR 139, Certification and Operations: Land Airports&lt;/a&gt;) also do not state a limit. The only reference to bodies of water of any kind is in §139.325 (Airport emergency plan) paragraph (e):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The plan required by this section&#xA;  shall contain provisions, to the extent&#xA;  practicable, for the rescue of aircraft&#xA;  accident victims from significant bodies&#xA;  of water or marsh lands adjacent to&#xA;  the airport which are crossed by the&#xA;  approach and departure flight paths of&#xA;  air carriers. A body of water or marsh&#xA;  land is significant if the area exceeds&#xA;  one-quarter square mile and cannot be&#xA;  traversed by conventional land rescue&#xA;  vehicles. To the extent practicable, the&#xA;  plan shall provide for rescue vehicles&#xA;  with a combined capacity for handling&#xA;  the maximum number of persons that&#xA;  can be carried on board the largest air&#xA;  carrier aircraft that the airport reasonably&#xA;  can be expected to serve.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, bottom line: there is no limit, but airports are required to take water into due consideration when developing emergency plans, and the FAA looks at each airport and plan on a case-by-case basis during airport certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the rest of the world, I have no authoritative information; but as others have posted, it certainly seems like the situation is the same, there being numerous examples of airports worldwide built on natural or reclaimed land &lt;em&gt;very&lt;/em&gt; close to water.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-03-28T14:36:13.133" LastActivityDate="2014-03-28T14:36:13.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2824" PostTypeId="2" ParentId="2822" CreationDate="2014-03-27T19:32:27.747" Score="8" Body="&lt;p&gt;Water is not an obstacle. There are plenty of examples around the world where runways are built on purpose-reclaimed land and the ocean starts just a handful of meters from the end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some random examples, check Nice-Côte d'Azur or Gibraltar or St. Maarten.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2014-03-27T21:34:44.847" LastActivityDate="2014-03-27T21:34:44.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2825" PostTypeId="2" ParentId="2699" CreationDate="2014-03-27T19:52:23.590" Score="20" Body="&lt;p&gt;Here is an interesting &lt;a href=&quot;http://avionics.nau.edu.ua/files/pdf/ATA23.pdf&quot;&gt;presentation&lt;/a&gt; that discusses most of the communications systems on the A320 family (looks like the pictures you have and should apply in general). The CIDS (cabin intercommunication data system) starts about halfway through on page 21. The FAP is part of this system and can control:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Passenger reading lights&lt;/li&gt;&#xA;&lt;li&gt;Passenger call buttons&lt;/li&gt;&#xA;&lt;li&gt;Cabin lighting controls&lt;/li&gt;&#xA;&lt;li&gt;Cabin system monitoring/testing&lt;/li&gt;&#xA;&lt;li&gt;Passenger entertainment system&lt;/li&gt;&#xA;&lt;li&gt;Passenger address (PA)&lt;/li&gt;&#xA;&lt;li&gt;Automatic announcement and boarding music&lt;/li&gt;&#xA;&lt;li&gt;Cabin/Service interphone and calls&lt;/li&gt;&#xA;&lt;li&gt;EVAC signal&lt;/li&gt;&#xA;&lt;li&gt;Emergency light&lt;/li&gt;&#xA;&lt;li&gt;Door bottle pressure monitoring (either oxygen or escape slide?)&lt;/li&gt;&#xA;&lt;li&gt;Door proximity sensors (doors closed properly)&lt;/li&gt;&#xA;&lt;li&gt;Smoke detection&lt;/li&gt;&#xA;&lt;li&gt;Water and waste tank quantities&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The acronyms you listed are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cabin Assignment Module (CAM)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;All the software for specific customer layouts and defined parameters in the FAP (same as OBRP).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;On Board Replaceable Module (OBRM)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This is a generic term for any module that is easily replaceable. In this case it refers to the module that contains all the information used by the FAP (same as CAM).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Prerecorded Announcement and Music (PRAM)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A good list of Airbus acronyms including these can be found &lt;a href=&quot;http://mobile.airlinetechs.com/airbus/Acronyms/acronyms.html&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IwPye.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="3425" LastEditDate="2014-09-05T14:49:46.853" LastActivityDate="2014-09-05T14:49:46.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2826" PostTypeId="2" ParentId="2822" CreationDate="2014-03-27T20:15:18.177" Score="12" Body="&lt;p&gt;There is no such limit indeed. &lt;a href=&quot;http://en.wikipedia.org/wiki/Princess_Juliana_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Princess Juliana International Airport&lt;/a&gt; in Sint Maarten is possibly the most iconic example of airport located near a water body, because of the beach over which airliners fly when approaching RWY 09. As other mentioned, they are numerous other examples of airports that may be even closer to a water body (i.e. without a beach in between).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PhlHZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://www.captmondo.com/?p=1878&quot; rel=&quot;nofollow noreferrer&quot;&gt;image source&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="94" LastActivityDate="2014-03-27T20:15:18.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2827" PostTypeId="1" AcceptedAnswerId="9423" CreationDate="2014-03-27T21:01:44.383" Score="13" ViewCount="491" Body="&lt;p&gt;After answering &lt;a href=&quot;https://history.stackexchange.com/questions/12233/u-s-biplane-identification&quot;&gt;this question&lt;/a&gt; on History.SE, I started to wonder if it would be possible to find out even more detail about the plane now that its serial number is known.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea what kind of flight records the US Army Air Corps kept, however. I know most flight logs today are kept by pilot, but I imagine there would be some way to trace what pilots flew a particular plane. I have no idea if this is possible for USAAC trainer planes in the 1930s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could I get access to these records? If so, how would I go about it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly interested in seeing if I can find out more information about where the plane flew, and maybe (if I'm lucky) who flew it when and for what purpose.&lt;/p&gt;&#xA;" OwnerUserId="44" LastEditorUserId="-1" LastEditDate="2017-04-13T12:47:54.013" LastActivityDate="2014-10-30T07:35:36.467" Title="Is it possible to get access to flight logs of USAAC trainer planes from the 1930s?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;military&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2828" PostTypeId="2" ParentId="2817" CreationDate="2014-03-27T21:20:13.790" Score="18" Body="&lt;p&gt;Even if the laser doesn't cause temporary or permanent injury to the pilots' eyes, it causes them to lose night vision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most well-known cause of this is the pupils of your eyes.  In the dark, the pupils open up to allow in as much light as possible. When they're exposed to a sudden bright light, they close up again. If the bright light goes away, it takes your eyes some amount of time (say, a minute or two) for your pupils to open again. During that time, you can't see very well at all. Not good, if you're trying to land a plane. You can experience this for yourself by playing around with the lights indoors at night: if you turn the lights off, you can see very little but, gradually, you begin to make things out as your pupils open. If you then turn the light back on, it feels uncomfortably bright until you get used to it again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less well-known is a chemical called &lt;a href=&quot;https://en.wikipedia.org/wiki/Rhodopsin&quot;&gt;rhodopsin&lt;/a&gt;, in the rod cells in your retina. Rhodopsin is extremely sensitive to light (even to single photons), and light makes it change shape. Other proteins bind to this new shape and a few little chemical reactions result in an amplified signal being sent to your brain. Most of your vision in the dark comes from the rod cells because of their high sensitivity; the other cells (the cones) require tens to hundreds of photons to fire so they're great for colour vision in decent light but not much use in the dark.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, being bound to other proteins means that the rhodopsin in your eyes is &quot;used up&quot; as light comes into your eyes. When its dark, this happens slowly enough that the rhodopsin can be regenerated but a sudden burst of bright light, such as from a laser, consumes all the rhodopsin in your eyes almost immediately.  Now, you're only seeing with the cones, and you're not seeing much. The really bad news is that it takes at least 5&amp;ndash;10 minutes for a decent amount of rhodopsin to regenerate and 30&amp;ndash;45 minutes to get back to the full amount. So now, your pilots are operating on quite seriously decreased vision for a substantial amount of time.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2014-03-28T10:51:54.153" LastActivityDate="2014-03-28T10:51:54.153" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2829" PostTypeId="2" ParentId="2822" CreationDate="2014-03-27T22:16:22.670" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://aviationtroubleshooting.blogspot.ca/2013/07/visual-approach-do-not-abandon-visual.html&quot;&gt;Runway 28L and 28R at KSFO&lt;/a&gt;, as well as 19L and 19R, have their thresholds right next to the San Francisco Bay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you recall, in July 2013, &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot;&gt;Asiana Airlines Flight 214&lt;/a&gt; landed short due to pilot error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In November 1968, &lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_2&quot;&gt;Japan Airlines Flight 2&lt;/a&gt; completely missed the runway and landed in San Francisco Bay.&lt;/p&gt;&#xA;" OwnerUserId="487" LastEditorUserId="487" LastEditDate="2014-03-27T22:25:34.827" LastActivityDate="2014-03-27T22:25:34.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2832" PostTypeId="2" ParentId="2816" CreationDate="2014-03-28T01:57:58.813" Score="13" Body="&lt;p&gt;Given the location of the snake from the photos/video in the article and the height of the wing/engine assembly (as shown below) I think it's entirely possible to miss this critter in preflight.  A visual inspection of the control surfaces is certainly a part of the preflight, but unlike on a small aircraft (say a Piper Cherokee or Cessna 172) you will probably not be getting &quot;up close and personal&quot; with the control surfaces - you would need a ladder to to so, and the sort of in-depth examinations that would require getting up on that ladder would probably normally be performed by maintenance personnel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot doing a preflight might get up on a ladder if they noticed something amiss (say a snake obviously hanging from the wing), but on a simple pre-filght visual inspection from the ground this unfortunate critter could easily be missed - particularly if it was curled up tightly in a small space as snakes are wont to do, and didn't have its body hanging out where it could be seen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smh.com.au/travel/travel-incidents/high-drama-qantas-pythons-flying-circus-20130110-2ciu0.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IBe1em.png&quot; alt=&quot;Snake on a Plane - from the linked video&quot;&gt;&lt;/a&gt;&lt;a href=&quot;https://i.stack.imgur.com/tcfE7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tcfE7m.jpg&quot; alt=&quot;Photo for scale - from Wikipedia&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-10-09T21:46:32.350" LastActivityDate="2014-10-09T21:46:32.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2833" PostTypeId="2" ParentId="2737" CreationDate="2014-03-28T02:38:07.650" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;My questions are:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1) When you enter the STAR in the the FMS, will it pre-populate the expected altitude, and does this show up in the FMS exactly the same&#xA;  as a mandatory crossing altitude?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on the model of FMS.  Some of them don't even have Vertical Navigation (VNAV), and it really depends on the exact model.  I will say that three of the most common FMS's that I have personally used (Universal, Collins, and Honeywell) all pre-populate the expected altitude and it shows up exactly the same as a mandatory altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, the FMS is advisory only.  Unless the pilot dials in the actual assigned altitude and selects a vertical mode on the autopilot, it isn't going to descend on its own.  So if ATC doesn't assign the crossing restriction, you may see your VNAV pointer come alive and watch as you fly through the vertical profile without capturing it and it would be perfectly normal.  If I am getting close to the point where I would like to descend to make a crossing restriction and haven't been given lower, I will sometimes ask the controller:  &quot;Do you need me to make the crossing restriction at RUGBB today?&quot;.  This gives me an idea of what's to come or prompts them to give me the descent clearance.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2) Are expected altitudes treated as suggestions by pilots or controllers? For example, in the above chart, if you were at JHAWK&#xA;  15,000ft landing south, and Kansas City Center or Approach told you to&#xA;  &quot;descend at your discretion, maintain 8000&quot;, would you (or the FMS)&#xA;  make any attempt to cross RUGBB at 12,000 even though it's not&#xA;  required?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An &quot;expect&quot; altitude is just that.  It is an altitude to expect, but it is not always actually assigned.  If it isn't, then you don't have to make it and since your example is at pilots discretion, you could descend at whatever rate you want.  You could cross RUGBB higher or lower than 12,000 ft and nobody would care.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In actual practice, they usually only do this in a few situations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If they have to hold you up higher due to traffic and you can no longer make the crossing restriction, they will just give you a &quot;descend and maintain&quot; altitude, sometimes with a &quot;good rate&quot; tacked on.&lt;/li&gt;&#xA;&lt;li&gt;It's a particularly slow time (late at night, etc.) and there isn't much other traffic to worry about.&lt;/li&gt;&#xA;&lt;li&gt;There is an aircraft at, say 13,000 ft. so they tell you to descend and maintain 14,000 ft with the intention of giving you the crossing restriction once you pass the conflicting traffic.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this last case, I would get down to 13,000 ft. in time to make the crossing restriction if they gave it to me, but it wouldn't be required.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3) How common is it for ATC to actually issue a &quot;cross [fix] at [altitude]&quot; where the fix and altitude are as expected on the chart?&#xA;  And, if it is common, why wouldn't it simply be mandatory?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again, this depends on the procedure but it is quite common.  That's why they put them there so that you can plan on what is typically done.  There may be operational reasons (like two different procedures that intersect) which prevent them from issuing it &lt;strong&gt;every&lt;/strong&gt; time, so they can't just make it mandatory.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;4) Are expected altitudes part of lost communications procedures?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Surprisingly, no.  Not unless the controller has specifically cleared you to expect or cross it or &quot;descend via&quot; a procedure.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5) Am I missing anything with regards to the purpose of expected altitudes?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not on this one!  In some cases, there is a speed restriction which is listed on a separate line from an expect altitude. In these instances, the speed is required whether or not the speed or altitude was verbally assigned, just by being cleared via the arrival. For example, on the SFO HADLY2 arrival, you are &lt;em&gt;required&lt;/em&gt; cross EUGEN at 250 knots, whereas 11,000ft is only required if assigned by ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9CoEZ.png&quot; alt=&quot;Approach plate excerpt&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="6" LastEditDate="2014-03-28T18:43:28.627" LastActivityDate="2014-03-28T18:43:28.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2837" PostTypeId="2" ParentId="2520" CreationDate="2014-03-28T08:04:04.757" Score="30" Body="&lt;p&gt;In my 10 years of flying 747s on international flights, there was no way we would know of passenger reactions upon landing unless one of the cabin staff told us, and that was rare.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-03-28T08:04:04.757" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2839" PostTypeId="1" CreationDate="2014-03-28T09:00:17.960" Score="9" ViewCount="593" Body="&lt;p&gt;Provided an aircraft with a fly-by-wire system, there are basically two possible choices when it comes deciding how to let the pilots interface with it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;rate control / attitude hold&lt;/strong&gt;: a deflection of the stick will command a certain rate, releasing it will make the system maintain the current attitude. See the Airbus Normal control law.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;direct control&lt;/strong&gt;: a deflection of the yoke will directly translate to a deflection of the surfaces, mimicking the &quot;old&quot; mechanical control setup. It is my understanding that this is the design choice of Boeing in its new aircrafts.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I do not wish to discuss how Airbus and Boeing made their design decisions, but rather see if there has been performed a study on what interface is preferred by pilots, eventually differentiating among private/commercial pilots or Airbus/Boeing certified pilots or even pure civil/(former) military pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does any of you have any reference?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="19" LastEditDate="2017-03-19T15:00:38.540" LastActivityDate="2017-05-01T07:56:50.740" Title="Have there been any studies on which fly-by-wire pilot interface is preferred; rate control or direct control?" Tags="&lt;fly-by-wire&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2840" PostTypeId="2" ParentId="258" CreationDate="2014-03-28T10:21:30.150" Score="13" Body="&lt;p&gt;Oddly enough, a malfunction of cabin heat (it was winter) was probably what brought to end the current &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2008/March/1/Endurance-Test-Circa-1958&quot;&gt;endurance record holder, a Cessna 172, at 64 days, 22 hours, and 19 minutes &lt;/a&gt; (which by the way is a great story to read in itself)&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-03-28T20:19:34.103" LastActivityDate="2014-03-28T20:19:34.103" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2841" PostTypeId="2" ParentId="258" CreationDate="2014-03-28T10:34:36.703" Score="2" Body="&lt;p&gt;There was infact an experiment to keep aircraft up weeks at a time, using nuclear reactors for energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard a few versions, but I believe that Americans never quite got it to work, but the Russians did (i heard sources say that most of their crews got irradiated to death in the process), while I've read other sources neither party got it to work, so I'm quite sure who to believe. In any case- virtually unlimited endurance and range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/a/ab/NB-36H_with_B-50%2C_1955_-_DF-SC-83-09332.jpeg&quot; alt=&quot;nuclear-plane&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess that would have meant that had they succeeded they could have stayed up for as long as most submarines stay down (which I think is like three months) ... maybe something to try with pilotless drones, where I could imagine that it could stay for pretty longer, engine condition permitting :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ps. I can't find any good sources on it, but I think that TU Delft was developing a drone for a 365-day mission duration with an environmental surveillance task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.century-of-flight.net/Aviation%20history/evolution%20of%20technology/nuke.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source 1&lt;/a&gt;/&lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-95LAL&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source 2&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.023" LastActivityDate="2014-03-28T10:34:36.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2842" PostTypeId="1" AcceptedAnswerId="2848" CreationDate="2014-03-28T12:35:48.687" Score="7" ViewCount="8993" Body="&lt;p&gt;I have read on wikipedia about airline fleets and you sometimes see that they have aircraft which they declare that have been stored. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically what does this mean? How do you store and aircraft? Being the plane out in the open air and susceptible to weather, wouldn't delicate parts and even the fuselage degrade quite quickly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are stored airplanes then reused or resold in the future?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it be more feasible just to sell them instead of storing them for a period of time?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2017-09-04T11:45:06.117" LastActivityDate="2017-09-04T11:45:06.117" Title="What does &quot;storing an aircraft&quot; technically mean?" Tags="&lt;aircraft-storing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2843" PostTypeId="2" ParentId="2842" CreationDate="2014-03-28T13:15:35.790" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.afm.aero/magazine/trading-legal-and-finance/item/285-aircraft-storage-the-costs-and-considerations&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; there are some nice considerations.&#xA;You can basically divide stored aircrafts in two main categories: short-term and long-term.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the link, for long-term:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When discussing parked or stored aircraft, it is safe to assume one is referring to an aircraft that is no longer in operation and has been placed by the owner, airline or lessor into a manufacturer-approved storage regime to preserve maintenance and asset value. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Instead, for short-term:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, some will also refer to stored aircraft as those that are between owners. [...] a transition [...] takes time and [...] As such, an aircraft will often be stored and out of revenue service for six to 12 weeks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Additional or unusually lengthy checks can delay the aircraft from revenue service for many months, during which time they are sometimes referred to as parked or stored. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;but in the end, to answer why they are not sold:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With the exception of these transitions, the majority of aircraft in storage are there because they are no longer economically viable to operate; &lt;strong&gt;it is cheaper to put the aircraft into a storage programme than to fly it.&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You keep it safe so that you can scrap it.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-03-28T14:00:26.430" LastActivityDate="2014-03-28T14:00:26.430" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2845" PostTypeId="1" AcceptedAnswerId="2847" CreationDate="2014-03-28T14:55:11.403" Score="7" ViewCount="11702" Body="&lt;p&gt;What is required for someone who holds a pilot certificate in one country to fly in another country? First, I'm wondering if there are any general rules that would apply to any such situation. Second, for the sake of a specific example, what would be required for someone who holds a private pilot certificate in the U.S. to fly an aircraft registered in the Philippines within the Philippines (assuming that the aircraft type is one for which the pilot is rated in the U.S.?) &lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2014-03-28T15:19:00.530" LastActivityDate="2019-07-06T23:24:21.667" Title="What is required for a pilot to fly in another country?" Tags="&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2847" PostTypeId="2" ParentId="2845" CreationDate="2014-03-28T15:30:03.907" Score="10" Body="&lt;p&gt;For your specific example, &lt;a href=&quot;http://www.caap.gov.ph/index.php/downloads/viewcategory/8-civil-aviation-regulation-car&quot; rel=&quot;nofollow noreferrer&quot;&gt;Philippines Civil Aviation Regulations Part 2&lt;/a&gt; (Personnel Licensing), section 2.2.4 covers &quot;Validation and Conversion of Foreign Licenses and Ratings.&quot; It states that a holder of a license from a &quot;Contracting State in accordance with ICAO Annex 1&quot; (this includes the United States) is eligible for &quot;validation&quot; of their foreign license. The validation process involves presenting the appropriate documentation of your license, ratings and logbook. For more than just PPL privileges, you must also pass a &quot;skill test&quot; and demonstrate the required knowledge and ability. The conversion (&quot;validation certificate&quot;) gives you the same ratings you had on your US license and is valid for 1 year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a very similar policy for foreign-to-US license conversion, covered in &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol2/pdf/CFR-2012-title14-vol2-sec61-75.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §61.75&lt;/a&gt;. As in the Philippines, the FAA does not require a skills test for private pilot privileges, but a written knowledge test is required for conversion of an instrument rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/183/i-have-a-european-easa-license-what-do-i-need-to-do-to-be-allowed-to-fly-in-th?rq=1&quot;&gt;Another question here on ASE&lt;/a&gt; discusses conversion from EASA (Europe) to FAA (US).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most other ICAO states recognize each other's licenses in a similar manner. In all cases you have to present your license and proof of experience, and in some cases pass a written test and/or checkride. I haven't look up the exact regulations for, say, EASA (Europe) or CAAC (China) but I'm sure they aren't far off from the examples above. In reality diplomatic considerations probably also come into play: a holder of an Iranian license would probably run into problems attempting to convert/validate their license in Israel, even though both are ICAO-contracting states, since they aren't on very good political terms to say the least. But this will likely be the exception rather than the rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(There are only 3 &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization#Membership&quot; rel=&quot;nofollow noreferrer&quot;&gt;non-ICAO states&lt;/a&gt;: Dominica, Liechtenstein and Tuvalu.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-03-28T15:56:12.017" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2848" PostTypeId="2" ParentId="2842" CreationDate="2014-03-28T15:48:17.913" Score="2" Body="&lt;p&gt;Depending on how long you are storing the plane, there are different options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some planes may be used or sold in the future. They are just waiting for the market conditions to improve so that the owner can afford to operate it again, or someone else would be willing to buy it. Some planes are too old for anyone to want to buy them. In this case, they are most useful to the current owner, so they store them in case they will be useful in the future. Another possibility is spare parts. While the plane is stored, it can be slowly disassembled to provide parts for other aircraft still in service. Once all useful parts are removed, it will be chopped up into scrap metal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recently, some new aircraft are being stored &lt;a href=&quot;http://aviationblog.dallasnews.com/2014/02/republic-airways-expects-to-park-some-airplanes-because-of-pilot-shortage.html/&quot; rel=&quot;nofollow noreferrer&quot;&gt;until they can find more pilots&lt;/a&gt;. There is also a case where the Air Force decided to purchase some planes, but later decided they didn't really need them. It's cheaper to send them to storage than cancel the contract, so &lt;a href=&quot;http://www.military.com/daily-news/2013/10/07/new-air-force-planes-go-directly-to-boneyard.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;straight to the desert they go&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can rent hangar space somewhere to store the plane. This is much harder to do for larger planes, and hangar space is expensive and limited. However, it obviously offers the best conditions for the plane, where it can be protected from the weather. This is more likely to be a short term solution unless the plane is very important (or the owner has deep pockets).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option is the &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_boneyard&quot; rel=&quot;nofollow noreferrer&quot;&gt;boneyard&lt;/a&gt;:&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/c/c1/B52sdestroyed.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vZINb.jpg&quot; alt=&quot;boneyard&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Areas like the US southwest have very low humidity year round, which reduces the amount of corrosion on an airframe. Airplanes are designed to be outside most of the time anyway, so they will hold up pretty well. Windows may be covered to keep the internal temperatures down, and certain gaps may be covered as well. Small airplanes may be completely wrapped in plastic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples of this include the boneyard at &lt;a href=&quot;http://en.wikipedia.org/wiki/309th_Aerospace_Maintenance_and_Regeneration_Group&quot; rel=&quot;nofollow noreferrer&quot;&gt;Davis Monthan AFB&lt;/a&gt; in Tucson, AZ, where the US military parks its planes, and nearby &lt;a href=&quot;http://en.wikipedia.org/wiki/Pinal_Airpark&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pinal Airpark&lt;/a&gt;, where many civilian aircraft are stored.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="69" LastEditDate="2014-03-28T16:23:42.943" LastActivityDate="2014-03-28T16:23:42.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2850" PostTypeId="1" AcceptedAnswerId="2852" CreationDate="2014-03-28T15:53:01.523" Score="16" ViewCount="48766" Body="&lt;p&gt;In the US, where are you allowed to fly RC aircraft? AMA says you should stay away from airports and below 400 feet. Is there any actual law about this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing you are free to fly on your own property. How about other places? Does it have to be an actual RC field? Can it be a park, as long as you don't endanger anyone?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this varies with local rules, is there some reference for finding more information about which areas allow/disallow it?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2017-07-09T20:48:52.087" Title="Where is RC aircraft flying allowed in the US?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;rc-aircraft&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2851" PostTypeId="2" ParentId="2845" CreationDate="2014-03-28T16:16:39.833" Score="5" Body="&lt;p&gt;It varies hugely depending on the country. Iceland simply allows the holder of an ICAO license to exercise the privileges of a PPL for up to 90 days with no additional tests or validation required aside from a current medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;a href=&quot;http://ericgideon.com/flying/travel/flying-in-iceland/&quot; rel=&quot;noreferrer&quot;&gt;did this myself a year ago&lt;/a&gt;, and was able to determine the requirements by simply emailing the ICAA, who responded promptly:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Foreign visitors in Iceland can use their valid and current ICAO pilot licence for three months for private VFR flights in Icelandic airspace in aeroplanes registered in Iceland. So as long you as licence is current and valid and you have sufficient privileges to fly the aeroplane in question. You can fly private VFR for three months in Icelandic airspace without having to validate your licence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is a difficult question to answer without country specifics, unfortunately. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-03-28T16:16:39.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2852" PostTypeId="2" ParentId="2850" CreationDate="2014-03-28T16:54:39.530" Score="13" Body="&lt;h2&gt;Update&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Everything in the second section (my original answer) used to be true (well, except for the first statement), but doesn't consider that the FAA Modernization and Reform Act of 2012 made this regulatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has &lt;a href=&quot;http://www.faa.gov/about/initiatives/uas/model_aircraft_operators/&quot; rel=&quot;nofollow noreferrer&quot;&gt;a webpage&lt;/a&gt; that discuss it in more detail , but here is an image that covers the basics:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/M0Q9U.png&quot; alt=&quot;What can I do with my model aircraft?&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a &lt;a href=&quot;http://www.faa.gov/about/initiatives/uas/media/model_aircraft_spec_rule.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;much more detailed letter of interpretation&lt;/a&gt; from the FAA which discusses their ability to enforce the regulation and many other parts of 14 CFR 91 if a model aircraft endangers another aircraft, flies within 5 miles of an airport without receiving a clearance, flies into a restricted area, etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The short version is that it isn't regulated (yet).  For more details, read on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA has an &lt;a href=&quot;https://www.faa.gov/uas/getting_started/fly_for_fun/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Unmanned Aircraft (UAS) Questions and Answers&lt;/a&gt; page on their website which addresses this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Do I need permission from the FAA to fly a UAS for recreation or as a hobby?&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There are two ways for recreational or hobby UAS fliers to operate in the National Airspace System in accordance with the law and/or FAA regulations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Option #1. Fly in accordance with the Special Rule for Model Aircraft (Public Law 112-95 Section 336). Under this rule, operators must:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fly for hobby or recreational purposes only&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Follow a community-based set of safety guidelines&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fly the UAS within visual line-of-sight&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Give way to manned aircraft&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Provide prior notification to the airport and air traffic control tower, if one is present, when flying within 5 miles of an airport&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fly UAS that weigh no more than 55 lbs. unless certified by a community-based organization&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Register the aircraft (UAS over 0.55 lbs. and less than 55 lbs. can be registered online at registermyuas.faa.gov; UAS 55 lbs. or greater must be registered through the FAA's paper-based process)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The other option is to obtain a pilot certificate and &lt;a href=&quot;https://www.faa.gov/uas/getting_started/fly_for_work_business/&quot; rel=&quot;nofollow noreferrer&quot;&gt;comply with part 107 UAS regulations.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has also published an Advisory Circular &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/79507BFB38DF5EA38625801E0066CDC0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Model Aircraft Operating Standards&lt;/a&gt;, which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1 - &lt;strong&gt;PURPOSE&lt;/strong&gt;. This advisory circular (AC) provides guidance to persons operating Unmanned Aircraft (UA) for hobby or recreation purposes meeting the statutory definition of “model aircraft” contained in Section 336 of Public Law 112-95, the FAA Modernization and Reform Act of 2012. This AC describes means by which model aircraft may be operated safely in the National Airspace System (NAS). Nothing in this AC changes the requirement to comply with the statute or any applicable regulations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6 - &lt;strong&gt;MODEL AIRCRAFT OPERATIONS&lt;/strong&gt;. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. Model Aircraft Hazards in the NAS. While aero-modelers generally are concerned about safety and exercise good judgment when flying model aircraft for the hobby and recreational purposes for which they are intended, they may share the airspace in which manned aircraft are operating. Unmanned aircraft, including model aircraft, may pose a hazard to manned aircraft in flight and to persons and property on the surface if not operated safely. Model aircraft operations that endanger the safety of the National Airspace System, particularly careless or reckless operations or those that interfere with or fail to give way to any manned aircraft may be subject to FAA enforcement action.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Determination of “Model Aircraft” Status. Whether a given unmanned aircraft operation may be considered a “model aircraft operation” is determined with reference to section 336 of Public Law 112-95:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The aircraft is flown strictly for hobby or recreational use;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The aircraft operates in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization (CBO);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The aircraft is limited to not more than 55 pounds, unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a CBO;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) The aircraft operates in a manner that does not interfere with, and gives way to, any manned aircraft; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) When flown within 5 miles of an airport, the operator of the model aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation. Model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the&#xA;  airport).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Public Law 112-95 recognizes the authority of the Administrator to pursue enforcement action against persons operating model aircraft who endanger the safety of the National Airspace System. Accordingly, model aircraft operators must comply with any Temporary Flight Restrictions (TFR).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Model aircraft must not operate in Prohibited Areas, Special Flight Rule Areas or, the Washington National Capital Region Flight Restricted Zone, without specific authorization.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;e. Model aircraft operators should follow best practices including limiting operations to 400 feet above ground level (AGL).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;f. All other operators and for additional information on Unmanned Aircraft Systems please visit: &lt;a href=&quot;http://www.faa.gov/uas/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/uas/&lt;/a&gt; .&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that this is &quot;guidance&quot; and recommended procedures that the FAA &quot;encourages voluntary compliance with&quot; in order to &quot;reduce the potential for hazards and create a good neighbor environment with affected communities and airspace users.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, any city/county/state could have rules on their books, but there is not national guidance for this.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="1696" LastEditDate="2017-02-13T19:30:13.273" LastActivityDate="2017-02-13T19:30:13.273" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2853" PostTypeId="2" ParentId="2753" CreationDate="2014-03-28T18:51:01.280" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm talking about the preflight checks that ensure that everything in the cockpit is setup correctly for takeoff. … Can this preflight check be done on the EFB? and can this be automated?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, and No -- You can certainly have a checklist on an EFB and complete it electronically (ticking each box as you verify the task was performed), but the actual performing of the tasks is still a manual process (it has to be, even with a &quot;Class 3 EFB&quot; built into the aircraft: If the computer is &quot;performing&quot; the tasks you've verified that the computer can do them - you still have to verify that the pilot's controls all operate correctly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, I have two sets of checklists in my aircraft - a &quot;quick reference&quot; checklist which is a simple laminated card which looks something like the one on the left, and a detailed electronic checklist on my iPad (a &quot;Class 1 EFB&quot;) which looks like the one on the right:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2fEVy.jpg&quot; alt=&quot;SureCheck Checklist&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/ScGSMm.gif&quot; alt=&quot;ForeFlight Checklist&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electronic checklist is nice because it can be much more detailed (you're not limited by the size of a physical piece of paper), and you're less likely to lose your place in the list if you're going through the items as a &quot;do-list&quot; (rather than using it to &quot;check&quot; that you performed all the steps).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-28T18:51:01.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2854" PostTypeId="1" AcceptedAnswerId="2856" CreationDate="2014-03-28T19:15:43.090" Score="43" ViewCount="15922" Body="&lt;p&gt;I've heard that in a lot of instances a jet that is making an emergency landing is required to dump excess fuel.  In a lot of instances this would make a lot of sense.  For example, if the gear cannot be lowered and the plane must land on its belly.   The last thing you want is a hundred tons of jet fuel involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, I have to assume there are also emergencies where a plane isn't required to dump its fuel.  I just am not sure what they would be?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question is: When are aircraft required to dump fuel before landing (or, at very least, when is it advisable to dump fuel before landing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;How much fuel does an aircraft retain after an emergency dump? I'm&#xA;assuming they don't dump it all or they would have no fuel to&#xA;maneuver with.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Examples would be great.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="97" LastEditDate="2014-10-29T01:12:56.900" LastActivityDate="2017-07-08T21:10:03.510" Title="When are aircraft required to dump fuel for emergency landings?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;emergency&gt;&lt;fuel-dumping&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2855" PostTypeId="2" ParentId="2854" CreationDate="2014-03-28T19:32:38.153" Score="12" Body="&lt;p&gt;The reason they &lt;a href=&quot;http://en.wikipedia.org/wiki/Fuel_dumping&quot; rel=&quot;noreferrer&quot;&gt;dump fuel&lt;/a&gt; is to keep the landing gear intact during the landing. A plane at max takeoff weight will not be kind to its gear. Max takeoff weight has to be equal or higher is also higher than max landing weight. A plane where max takeoff weight is within 5% of max landing weight doesn't need to be able to dump fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there isn't a designated fuel dumping site (typically a nearby lake or ocean) or the plane can't make it there to dump fuel, they will instead circle around until the fuel level has dropped sufficiently. This is not possible when the emergency is of the kind that needs to be on the ground NOW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A recent incident that had a fuel dump is &lt;a href=&quot;http://avherald.com/h?article=471d8035&amp;amp;opt=0&quot; rel=&quot;noreferrer&quot;&gt;Air France B773&lt;/a&gt;. Another incident where they couldn't dump fuel is &lt;a href=&quot;http://avherald.com/h?article=470be1bb&amp;amp;opt=0&quot; rel=&quot;noreferrer&quot;&gt;Delta B763&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="567" LastEditDate="2014-08-14T13:14:44.033" LastActivityDate="2014-08-14T13:14:44.033" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2856" PostTypeId="2" ParentId="2854" CreationDate="2014-03-28T19:35:05.457" Score="48" Body="&lt;p&gt;For many medium and large sized jets the maximum gross takeoff weight is higher than the maximum landing weight.  If the airplane has an emergency that requires an air return or other landing in the early part of flight, it is very likely overweight for landing.  The plane has 3 options at this point:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Land overweight&lt;/li&gt;&#xA;&lt;li&gt;Dump fuel (if able)&lt;/li&gt;&#xA;&lt;li&gt;Fly around at low altitude and high power to burn fuel&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For some airplanes, option 2 is not available.  This includes airplanes that are not equipped to dump fuel (not all airplanes have this capability or have the capability under MEL) or are not approved to dump fuel at their current location and altitude.  For these airplanes, only option 1 and 3 are available.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The choice between option 1 and 2/3 comes down to what kind of emergency it is.  If you have to be on the ground &lt;strong&gt;now&lt;/strong&gt;, you won't care about being overweight, and will just put it down.  If you have time and landing now isn't a priority, then you would choose to dump or burn fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airplane chooses to dump, they will generally choose one of two values of remaining fuel:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;fuel such that they land at the maximum landing weight&lt;/li&gt;&#xA;&lt;li&gt;absolute minimum safe fuel to land&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This choice comes down to how likely the landing will end in an accident.  If you are sure the landing will be a non-event (e.g. air return for anti-ice failure) then you'll likely just dump until landing wont be overweight.  Conversely, if you have a control issue or something that may end badly, you want minimum fuel to lessen the potential for fire.  In these cases the ARFF crew will spray the runway with foam to assist in reducing the fire potential.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-03-28T19:41:36.717" LastActivityDate="2014-03-28T19:41:36.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2857" PostTypeId="2" ParentId="2854" CreationDate="2014-03-28T19:46:53.877" Score="24" Body="&lt;p&gt;The primary reason is to reduce the weight of an aircraft. Aircraft are designed to land at a maximum weight lower than their maximum weight. In order to be under that maximum landing weight, they must either burn that fuel during flight or dump it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no &lt;strong&gt;requirement&lt;/strong&gt; for them to dump fuel. This decision is up to the pilot. They may choose to land the aircraft &quot;overweight&quot;, meaning over the maximum landing weight. In this case the aircraft will have to undergo an inspection to ensure that nothing was damaged. On some aircraft, an inspection is only required if the touchdown acceleration was over a certain amount (like 1.7G).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dumping fuel will generally be an issue with a plane that has taken off for a long flight and has to divert for some issue. The pilot must decide how urgent the emergency is. If it is an urgent problem, such as &lt;a href=&quot;http://avherald.com/h?article=46995372&quot;&gt;engine failure&lt;/a&gt;, medical emergency, hydraulic issues, or fire, their priority is to land ASAP regardless of weight. They may dump fuel while headed to a diversion airport if they can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the emergency is &lt;a href=&quot;http://avherald.com/h?article=4718ca64&quot;&gt;not as urgent&lt;/a&gt;, the pilot may decide that they do not want to continue the flight, especially if it involves long stretches over water without diversion airports. In this case they can hold somewhere near a diversion airport to burn off or dump fuel until they are comfortable with their landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the 777-200ER can take off at 656,000 lb, but maximum landing weight is 470,000 lb. This means they could have to dump 150,000 lb of fuel if they encounter an issue at the beginning of a long flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount they leave after dumping will be up to the pilot. For serious gear issues, they may want to be as light as possible and only leave a minimum amount of fuel in the tanks (on a 737, this is about 4,000 lb). For other instances, they may be satisfied with the maximum landing weight and not want to spend any more time dumping or burning fuel. No pilot wants to dump a bunch of fuel and then end up needing it later.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-03-28T19:52:38.457" LastActivityDate="2014-03-28T19:52:38.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2858" PostTypeId="1" AcceptedAnswerId="2860" CreationDate="2014-03-28T20:01:14.807" Score="17" ViewCount="22915" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/2854/when-are-aircraft-required-to-dump-fuel-for-emergency-landings/2856?noredirect=1#comment5587_2856&quot;&gt;this question&lt;/a&gt; about aircraft dumping fuel I was told that there may possible be guidance in the QRH.  I know that there are a lot of guidelines given to pilots, but I've never heard of this one.  Would anyone care to explain, from a pilots perspective, what exactly a QRH is and how it's used in modern aircraft operation?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2018-04-15T02:22:49.137" LastActivityDate="2018-04-15T02:22:49.137" Title="What exactly is a QRH?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2859" PostTypeId="2" ParentId="2858" CreationDate="2014-03-28T20:08:41.520" Score="10" Body="&lt;p&gt;A QRH is a Quick Reference Handbook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is basically the checklist used in the aircraft along with other useful information, which varies from QRH to QRH, but can include things like system diagrams, maximum cruising altitudes for the current conditions, takeoff and landing performance, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is usually a small form, spiral bound document that is convenient and easy-to-use in the cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://i.ebayimg.com/t/Airbus-A320-A321-A319-QRH-Quick-Reference-Handbook-aviation-flight-sim-MSFS-/00/s/MTE5NVgxNjAw/z/pnwAAOxy-1lRHPyp/$T2eC16dHJF8E9nnC8Hc-BRHPypWmeg~~60_35.JPG&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b9GDE.jpg&quot; alt=&quot;Airbus QRH&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-03-28T20:08:41.520" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2860" PostTypeId="2" ParentId="2858" CreationDate="2014-03-28T20:26:21.500" Score="16" Body="&lt;p&gt;A QRH is a Quick Reference Handbook and is an approved (by some overseeing entity) document specific to an airplane and operator that contains checklists for just about anything the airplane can experience.  At my airline we had copies in the airplane and also in our company flight manual (CFM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The entry point into a QRH checklist is one of a few things&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Memory items&lt;/li&gt;&#xA;&lt;li&gt;EICAS message&lt;/li&gt;&#xA;&lt;li&gt;An abnormal event&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For option 1, there are various checklists that must be memorized and performed at a moments notice with no reference to the checklist.  Some of these are things like trim runaways, engine fire/severe damage, emergency descent.  Once the memory part of the checklist is complete you refer to the printed version of the checklist in the QRH to verify and perform additional steps beyond the part you were required to memorize.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the other options, any time anything abnormal happens or an EICAS message is presented, there are indices by procedure name and also by EICAS message into a specific procedure in the QRH to follow.  These procedures may reference other procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, If I were to experience a dual engine failure, I would pick up my QRH and find the procedure &quot;DUAL ENGINE FAILURE&quot;, this procedure says I should have the master warning light illuminated (and an aural triple chime) and I should see the EICAS message (in red) &quot;ENG 1-2 OUT&quot;.  After verifying this presentation and verifying I am in the right procedure, I would perform:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Airspeed....................MINIMUM 260 KIAS&#xA;Altitude....................MAXIMUM FL250&#xA;Oxygen Mask (if required)...DON&#xA;APU.........................START&#xA;ENGINE AIRSTART procedure...PERFORM  (note, this is another QRH procedure)&#xA;&#xA;CAUTION: IF THE APU HAS BEEN USED TO START THE ENGINES, &#xA;         DO NOT ALTERNATE THE FADECs AFTER START&#xA;&#xA;Note: If the APU is not available, only equipment supplied by the &#xA;      Essential DC Bus 1 and 2 will be available.  Engine windmilling &#xA;      should drive engine driven hydraulic pumps and supply hydraulic&#xA;      pressure.&#xA;&#xA;IF neither engine can be restarted:&#xA;    DITCHING or FORCED LANDING procedure......PERFORM &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="258" LastEditorUserId="1467" LastEditDate="2016-06-09T16:37:08.003" LastActivityDate="2016-06-09T16:37:08.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2861" PostTypeId="1" CreationDate="2014-03-28T21:06:01.053" Score="8" ViewCount="12606" Body="&lt;p&gt;Is there something like a health requirement in serious airlines? Or is it just a myth? How are potential pilots screened when it comes down to physical requirements?&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="97" LastEditDate="2014-03-30T23:31:10.293" LastActivityDate="2014-03-30T23:32:57.853" Title="Can I be a commercial pilot if I've had a dental filling?" Tags="&lt;flight-training&gt;&lt;medical&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2862" PostTypeId="1" AcceptedAnswerId="2864" CreationDate="2014-03-28T21:07:26.563" Score="28" ViewCount="5650" Body="&lt;p&gt;Aircraft use nav fixes as waypoints or reporting points along their routes. I have noticed some interesting combinations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some make sense, like LUCKI to LYNDI on the LYNDI arrival into San Diego International, known as Lindbergh Field, or KSINO LUXOR on the GRNPA arrival into Las Vegas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some are more interesting, like HIMOM KALME on the FRNCH arrival into Denver, or ASTAH LVSTA ADYOS on the ADYOS departure from Albuquerque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some get downright suspicious, like ITUNE MUSCC DWNLD on the LOWBO arrival into Albuquerque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: how do these points get named? These combinations are memorable, but are they also allowed to be sponsored? Or is this a case of &quot;Any resemblance to actual entities is entirely coincidental.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2020-10-29T21:55:48.893" Title="How are airspace fixes named?" Tags="&lt;navigation&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2863" PostTypeId="2" ParentId="2861" CreationDate="2014-03-28T21:27:26.530" Score="2" Body="&lt;p&gt;Dental fillings, false teeth, implants are all permitted so long as the mouth is healthy and there are no abcesses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial pilots need a first class medical certificate.  I don't have that reference here with me now, but perhaps someone can post either a link to the requirements for a first class medical, or list the requirements here.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-03-28T21:27:26.530" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2864" PostTypeId="2" ParentId="2862" CreationDate="2014-03-28T22:05:07.463" Score="15" Body="&lt;p&gt;In the US, they are assigned by a division in the FAA called &lt;a href=&quot;https://nfdc.faa.gov/aimnews/&quot;&gt;Aeronautical Information Management (AIM)&lt;/a&gt;, per &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/AIR.pdf&quot;&gt;FAA Order JO 7400.2J&lt;/a&gt; (Procedures for Handling Airspace Matter), section 3-3-2:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. Service area office are responsible for assigning and changing names of NAVAID and aeronautical facilities, and must follow the instructions contained&#xA;  herein and in FAAO JO 7350.8, Location Identifiers, Chapter 1.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. AIM is responsible for issuing five−letter names for radio fixes, waypoints, marker beacons, and compass locators. Five−letter names must be issued by AIM to the Terminal Procedures and Charting Group, Major Military Commands (MAJCOM) and Air Route Traffic Control Centers (ARTCC) for future assignments.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's conceivable they accept suggestions from ARTCCs or other entities. I don't know. I doubt paid sponsorship is approved but have no first hand knowledge there. Suggestions are probably casual and intormal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are often quite amusing, like &lt;a href=&quot;http://www.theatlantic.com/national/archive/2013/10/itawt-itawa-pudye-ttatt-the-secret-language-of-the-skies/280598/&quot;&gt;ITAWT ITAWA PUDYE TTATT&lt;/a&gt;. Very often enroute fixes are named for small towns or other points of interest near the fix.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-03-28T22:13:34.877" LastActivityDate="2014-03-28T22:13:34.877" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2865" PostTypeId="2" ParentId="2854" CreationDate="2014-03-28T23:01:07.050" Score="17" Body="&lt;p&gt;In reference to how much fuel is retained, in the 747-100 and -200 aircraft it was not possible to run yourself out of fuel by dumping. There were stand pipes in the the system that prevented that. A common call to the flight engineer in the simulator for certain emergencies was to &quot;dump down to the stand pipes.&quot; Offhand I don't remember how much fuel was left when that was done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most fuel I ever dumped to get down to max landing weight (635,000 lbs as I remember) was around 100,000 lbs. We did it at 4,000 feet over the ocean off Lima, Peru after an engine blew (it literally disintegrated inside) on takeoff. As I remember, we believed that dumped fuel evaporates in 2 to 3 thousand feet of fall, so we did not believe it would reach the water. Not that that was any consideration at the moment.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-03-28T23:01:07.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2866" PostTypeId="1" AcceptedAnswerId="2868" CreationDate="2014-03-29T00:31:28.867" Score="36" ViewCount="4334" Body="&lt;p&gt;If one wanted to, how large part of the flight could a modern commercial airliner do completely on its own? That is, if the pilot only was allowed to set things up and then leave the cockpit, from where (taxiing, take off, et cetera) and for how long would the airplane be able to handle things itself before things went out of hands?&lt;/p&gt;&#xA;" OwnerUserId="1884" LastEditorUserId="1884" LastEditDate="2014-03-29T00:50:56.307" LastActivityDate="2017-01-03T15:01:50.520" Title="On modern commercial airliners, how much of the flight could be fully taken care of by the auto pilot?" Tags="&lt;autopilot&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2867" PostTypeId="2" ParentId="2862" CreationDate="2014-03-29T00:55:06.313" Score="13" Body="&lt;p&gt;As well as the FAA's part mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/questions/2862/how-are-airspace-fixes-named/2864#2864&quot;&gt;dvnrrs's answer&lt;/a&gt;, they are also part of ICAO's 5LNC (Five-Letter Name-Code) system, which records available pronounceable 5 letter codes (they don't have to be words).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While these are meant to be unique, there are several cases where different countries have duplicate names from legacy naming systems. As of February 2014, there are 130 codes that are duplicates of others in other countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, there is usually some form of selection to prevent similar-sounding names from being used as a 5LNC in the area. For example, the UK Civil Aviation Authority states that (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Where a significant point is required at a position not marked by the site of a radio &#xA;  navigation aid, the significant point shall be designated by a unique five letter &#xA;  pronounceable ‘name-code’ (5LNC). This name-code designator then serves as the &#xA;  name as well as the coded designator of the significant point and shall be selected so &#xA;  as to avoid any difficulties in pronunciation by pilots or ATS personnel when speaking &#xA;  in the language used in ATS communication. The name-code designator shall be &#xA;  easily recognisable in voice communications and &lt;strong&gt;shall be free of ambiguity with those &#xA;  used for other significant points in the same general area&lt;/strong&gt;. The name-code &#xA;  designator assigned to a significant point shall not be assigned to any other &#xA;  significant point. (Reference B)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2018-04-24T06:45:29.337" LastActivityDate="2018-04-24T06:45:29.337" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2868" PostTypeId="2" ParentId="2866" CreationDate="2014-03-29T02:44:40.793" Score="39" Body="&lt;p&gt;This should apply to the most advanced modern airliners. Older aircraft may not have all of the same automation available. The autopilot can take care of most tasks between takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots have to take care of starting the airplane. This includes turning on electronics, bringing up the aircraft systems, and starting the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxiing is pretty much on the pilot, there is no automatic taxi yet on commercial airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft is lined up with the runway, the pilot can hit the TOGA (Takeoff/Go Around) button. The plane will automatically apply the right amount of thrust for takeoff. The pilot will then rotate the plane (lift the nose) at the rotation speed (calculated before the flight), and the plane lifts off. Shortly after that, the pilot will engage the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is set up to follow GPS waypoints and proper altitudes, it will be able to take care of the climb, cruise, and descent portions of the flight. The autopilot can follow the best speeds and fly through each waypoint in the flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft is approaching the runway, the pilot will tune the proper ILS frequency for the runway into the navigation radio. They will then engage the Approach mode, which captures the localizer (lateral navigation left/right to align with the runway) and glideslope (veritical navigation up/down to have the proper approach path). The pilot then needs to deploy the flaps and landing gear as the plane slows down for landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the lowest visibility conditions, the plane is capable of the approach and touchdown on the runway all by itself. The pilot will then apply reverse thrust and brakes as needed to slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that the plane is back on the ground, it is once again the pilot's job to exit the runway and taxi to the gate. Shutting down the engines and then the electronics will also be up to the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the autopilot still missing?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Responding to ATC (readback clearances, change frequencies)&lt;/li&gt;&#xA;&lt;li&gt;Reacting to nearby traffic&lt;/li&gt;&#xA;&lt;li&gt;Following ATC instructions (climb/descend, turn, slow/accelerate)&lt;/li&gt;&#xA;&lt;li&gt;Reacting to emergencies or system failures&lt;/li&gt;&#xA;&lt;li&gt;Controlling lights, flaps, landing gear&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is of course a high level view and there is so much more that goes into the flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, keep in mind that we have the technology to do much more. It just hasn't made it into service for one reason or another (lack of development and testing, not seen as important, etc.). We have UAVs that are much more automated than this. However, they are still working on how to effectively avoid other aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-03-30T02:36:48.640" LastActivityDate="2014-03-30T02:36:48.640" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2869" PostTypeId="1" CreationDate="2014-03-29T09:47:13.740" Score="12" ViewCount="4177" Body="&lt;p&gt;How deep can black boxes go under water and how much pressure can they withstand while under water before they get crushed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I'm a layman in terms of aviation, so if it's not too much to ask, can you answer as easily understandable as you can?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1892" LastEditorUserId="22726" LastEditDate="2019-04-27T03:42:52.377" LastActivityDate="2019-04-27T03:42:52.377" Title="How much water pressure can flight recorders withstand?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2870" PostTypeId="2" ParentId="2869" CreationDate="2014-03-29T11:27:30.390" Score="18" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;How deep can black boxes go under water?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;They are required to be able to withstand a depth of 20,000 feet (3.8 miles, 6.1 km) for 30 days.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;&amp;amp; how much pressure can they withstand?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;At 20,000 feet deep the pressure is 8900 pounds per square inch (psi) which is 606 times atmospheric pressure at sea level (nearly 4½ tons on each square inch of surface)&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BpeSm.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;A flight data recorder from AF447, around 13,000 feet deep for almost 2 years. Still readable&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;References&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The DFDR must be watertight to a depth of 20,000 feet in sea water, and survive at this depth for 30 days&lt;/p&gt;&#xA;&lt;p&gt;The units also have to withstand a static crushing force at all of its six axis points of an applied load force of 5,000lbs for 5 minutes on each axis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;See: &lt;a href=&quot;https://aviation.stackexchange.com/q/2406/1289&quot;&gt;What happens to the transponder, FDR and CVR in case of an explosion?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The southern corridor of the Indian Ocean, where officials now believe the plane went down, ranges in depth from 3,770 feet to 23,000 feet.  At its greatest depth, that’s almost equal to the height of Mount Everest (which measures 29,029 feet tall).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;See: &lt;a href=&quot;http://www.msnbc.com/hardball/indian-ocean-depth-challenges-search-crews&quot; rel=&quot;noreferrer&quot;&gt;Indian Ocean depth proves great challenge for MH370 search crews&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JEe7y.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi (1 bar).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;See also&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders&quot; rel=&quot;noreferrer&quot;&gt;List of unrecovered flight recorders&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-13T15:07:29.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2871" PostTypeId="1" CreationDate="2014-03-29T13:26:21.400" Score="7" ViewCount="72707" Body="&lt;p&gt;How can I calculate with known tangents of different angles and by rules of thumb?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which formulae should I use for fps and NM?&lt;/p&gt;&#xA;" OwnerUserId="1876" LastEditorUserId="97" LastEditDate="2014-04-17T00:31:28.280" LastActivityDate="2021-02-15T10:59:23.850" Title="How to calculate angular velocity and radius of a turn?" Tags="&lt;aerodynamics&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2872" PostTypeId="2" ParentId="2871" CreationDate="2014-03-29T14:54:01.790" Score="19" Body="&lt;p&gt;Your terminology is a little confusing, but I'm going to assume you're asking how to calculate &lt;em&gt;turn radius&lt;/em&gt; and &lt;em&gt;rate of turn&lt;/em&gt; based on airspeed and bank angle. These formulas can all be found in the FAA's &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/06_phak_ch4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; which is available for free online.&lt;/p&gt;&#xA;&lt;p&gt;The Handbook gives the formulas for rate of turn and turning radius on &lt;strong&gt;page 4-34&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$R=\frac{V^2}{11.26\tan\theta}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\omega=\frac{1,091\tan\theta}{V}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;The variables used are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$V$&lt;/span&gt; = true airspeed in knots&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$R$&lt;/span&gt; = turning radius in feet&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\theta$&lt;/span&gt; = bank angle in degrees&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; = rate of turn in degrees per second&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;For example, at 120 knots and a 30° bank angle, the turn radius and rate of turn are:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$R=\frac{120^2}{11.26\tan30}=\frac{14,400}{11.26\times0.5773}=2,215 feet\approx\frac13nautical~mile$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\omega=\frac{1,091\tan30}{120}=\frac{1,091\times0.5773}{120}=5.25°/sec$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;The &amp;quot;magic constants&amp;quot; in these formulas (&lt;span class=&quot;math-container&quot;&gt;$11.26$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$1,091$&lt;/span&gt;) are conversion factors for the units involved (knots, feet, and degrees). Physicists would use unitless formulas involving &lt;span class=&quot;math-container&quot;&gt;$g$&lt;/span&gt;, acceleration due to gravity (roughly &lt;span class=&quot;math-container&quot;&gt;$9.8m/sec^2$&lt;/span&gt;).&lt;/p&gt;&#xA;&lt;p&gt;You can also rearrange the formulas above using simple algebra to figure out the required bank angle given a desired rate of turn or turn radius.&lt;/p&gt;&#xA;&lt;p&gt;Finally, note that things get a lot more complicated if you factor in &lt;em&gt;winds aloft&lt;/em&gt;. Rate of turn will always be the same regardless of wind, but &lt;em&gt;turning radius&lt;/em&gt; no longer applies because the aircraft will trace a spiral path along the ground, not a circle. The turn will be &amp;quot;sharper&amp;quot; on the upwind portion of the turn and &amp;quot;wider&amp;quot; on the downwind portion. This is why &lt;em&gt;turns around a point&lt;/em&gt; is a complex maneuver taught in basic flight training: in order to fly a circular ground track, the pilot must constantly vary the aircraft's bank angle according to wind: lower bank angle upwind, higher bank angle downwind. The pilot must also use the rudder correctly to keep the turn coordinated at all times.&lt;/p&gt;&#xA;&lt;p&gt;Other useful links:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; (quoted above)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://edwilliams.org/avform.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Formulary&lt;/a&gt; has a section on &lt;a href=&quot;http://edwilliams.org/avform.htm#Turns&quot; rel=&quot;nofollow noreferrer&quot;&gt;turns&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/ROT_%28aviation%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Standard rate turn&lt;/a&gt; article on Wikipedia&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Banked_turn#Banked_turn_in_aeronautics&quot; rel=&quot;nofollow noreferrer&quot;&gt;Banked turn&lt;/a&gt; article on Wikipedia&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;There are also some &amp;quot;Related Questions&amp;quot; over on the right-hand side of this page that might be useful.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="25943" LastEditDate="2020-12-30T07:26:49.073" LastActivityDate="2020-12-30T07:26:49.073" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="2873" PostTypeId="1" AcceptedAnswerId="2884" CreationDate="2014-03-29T15:45:00.737" Score="94" ViewCount="47759" Body="&lt;p&gt;For a layman like myself, the cockpit of every single modern airplane that I've laid my eyes on seems like a complex, intimidating mess with knobs, buttons, screens and levers literally covering every single square centimeter. Every time when seeing this, from my point of view, chaos of control surfaces and indicators, I'm always thinking to myself &quot;This HAS to be possible to make easier!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe my intuition is correct. Maybe it isn't. Anyhow, I can see a lot of possible reasons why one actually would want cockpits to be designed in this way. Maybe it makes it harder for an amateur to just wing it (no pun intended) and make it looks like (s)he knows what (s)he's doing. Maybe it forces the pilot to really understand every single nuance of the plane and its operation before even being able to taxiing. Maybe it fosters speed and security in an emergency situation by having everything accessible right away, accessible through muscle memory on the part of the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or maybe most cockpit designers like to make the operation of aircraft a pain in the behind for everybody else. I don't know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the design philosophy behind the design of the cockpit controls?&lt;/p&gt;&#xA;" OwnerUserId="1884" LastEditorUserId="3201" LastEditDate="2015-05-30T18:09:09.443" LastActivityDate="2020-11-29T14:39:39.357" Title="Why are the cockpit controls of airplanes so complicated?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;cockpit&gt;" AnswerCount="14" CommentCount="18" FavoriteCount="30" ContentLicense="CC BY-SA 3.0" />
  <row Id="2874" PostTypeId="2" ParentId="2873" CreationDate="2014-03-29T15:50:48.387" Score="46" Body="&lt;p&gt;99% of the information provided by all of those gauges, and 90% of the possible positions of all of those controls, are not necessary on a typical flight. You CAN take off, fly, and land, with just the instruments used on an ultralight (or less, if you think about the paramotor folks). But if &lt;em&gt;anything&lt;/em&gt; goes wrong, or to squeak out a tiny bit more efficiency, you will want at least some of that extra info and extra control, and you don't know which things you'll need until something goes wrong, so &lt;em&gt;everything&lt;/em&gt; is provided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Analogously, many people who soup up street cars to race them will install many additional gauges and controls, which normal drivers don't want or need. Temperature monitors for specific parts of the car, toggles for different valves and sensors, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pNWlx.jpg&quot; alt=&quot;ultralight plane gauge cluster pod&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1895" LastEditorUserId="-1" LastEditDate="2014-05-05T19:48:12.940" LastActivityDate="2014-05-05T19:48:12.940" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2875" PostTypeId="2" ParentId="2871" CreationDate="2014-03-29T16:41:19.240" Score="7" Body="&lt;p&gt;If you're going to do this in a cockpit, a good rule of thumb will help more than an exact formula:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Bank angle for rate 1 turn is $\frac{speed}{10}+7$.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Turn diameter is 1% of the speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;eg. for a 120kts turn you need $\frac{120}{10}+7=19°$ of bank and have a $\frac{120}{100}=1.2$nm turn diameter&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="97" LastEditDate="2014-04-18T03:38:58.220" LastActivityDate="2014-04-18T03:38:58.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2876" PostTypeId="2" ParentId="2861" CreationDate="2014-03-29T17:20:49.983" Score="8" Body="&lt;p&gt;Here are the &lt;a href=&quot;http://flightphysical.com/Exam-Guide/HEENT/Mouth-28.htm&quot; rel=&quot;nofollow&quot;&gt;mouth and throat requirements&lt;/a&gt; for a pilot physical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main thing is that it shouldn't affect your ability to fly (i.e. having pain) and ability to communicate over the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial pilots who don't fly regular schedules need a Class 2 medical certificate. Regular schedule commercial pilots need a Class 1.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://flightphysical.com/part67/Class2/67subc.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Class 2 medical requirements&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://flightphysical.com/part67/Class1/67subb.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Class 1 medical requirements&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1868" LastEditorUserId="97" LastEditDate="2014-03-30T23:32:57.853" LastActivityDate="2014-03-30T23:32:57.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2877" PostTypeId="2" ParentId="2873" CreationDate="2014-03-29T20:14:16.877" Score="43" Body="&lt;p&gt;The controls of an airplane don't have to be complicated. Here is a typical modern glider control panel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WK1xt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These instruments are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(top left) Variometer (shows relative climb/sink, only really useful for gliders)&lt;/li&gt;&#xA;&lt;li&gt;(top centre) Airspeed (required)&lt;/li&gt;&#xA;&lt;li&gt;(top right) Another variometer (in this airplane, one is mechanical and one is electronic)&lt;/li&gt;&#xA;&lt;li&gt;(bottom left) Altimeter (required)&lt;/li&gt;&#xA;&lt;li&gt;(centre) Compass (required)&lt;/li&gt;&#xA;&lt;li&gt;(bottom centre) Temperature&lt;/li&gt;&#xA;&lt;li&gt;(bottom right) VHF Radio controls&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The instruments labeled (required) above are the minimum necessary for any aircraft. The controls not shown in this picture are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Control stick&lt;/li&gt;&#xA;&lt;li&gt;Rudder pedals&lt;/li&gt;&#xA;&lt;li&gt;Airbrakes&lt;/li&gt;&#xA;&lt;li&gt;Landing wheel lever&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, gliders don't typically have engines, cabin pressurisation systems, hydraulic controls, fuel pumps, autopilot, navigational systems (ILS, VOR, DME, etc), HF radio, PA system, fire suppression, and so on. In particular, a modern jet engine (just the engine) is tremendously complicated and has many possible control inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike a road vehicle, if something goes wrong in an aircraft during flight the pilot can't just pull over to the side of the road and call for help (of even just get out and look in the engine compartment). The pilot needs full control over all the aircraft systems, directly from the cockpit, in order to be able to control the aircraft safely in case of an emergency.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-29T20:14:16.877" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="2878" PostTypeId="2" ParentId="2873" CreationDate="2014-03-29T21:16:25.987" Score="24" Body="&lt;p&gt;As others have pointed out, you can have a pretty simple instrument panel if you go with the bare minimum required instruments on the simplest possible aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect you're more interested in aircraft with panels like like this one though:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hfMhv.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hfMhv.jpg&quot; alt=&quot;Sport Cruiser panel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we think about these aircraft you're actually seeing the &quot;simplified&quot; version - or at least the standardized version.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the pilot's (left) side, there are six standard flight instruments: an airspeed indicator, an artificial horizon, and an altimeter on the top row, and a turn coordinator, directional gyro, and vertical speed indicator on the bottom. These six instruments in this layout are &quot;the standard six-pack&quot;, and without going into what each one does it should suffice to say that they're the instruments a pilot is going to refer to most in flight, so the designers put them right in front of the pilot.&lt;br&gt;&#xA;On the bottom of the pilot's side panel are switches for things like the interior and exterior lights, and a key-switch for the ignition (this particular aircraft has about 10 switches - they're all labelled, though you can't read the labels in this picture).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the co-pilot's (right) side are a bunch more gauges which all have to do with the operation of the engine (the equivalent of the fuel gauge, oil pressure, coolant temperature, and tachometer in a sports car), and two rows of circuit breakers (unlike in a car where the fuse box is hidden away in an aircraft you may need to reset a breaker or replace a fuse in flight, so they're out and accessible - and like the switches they're all labeled).&lt;br&gt;&#xA;Most of the time you'll only give this side of the panel an occasional glance during flight - since you don't need to look at this information all the time it's put off on the side &quot;out of the way&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Down the center is the &quot;radio stack&quot; - a compass (up at the top) and a bunch of radios for navigation, communication, and ATC identification. Not &quot;necessary&quot;, but helpful.&lt;br&gt;&#xA;Between the seats you see a valve for controlling the fuel (the big red thing), and a throttle (the black lever between the seats).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;While the panel may look intimidating at first the important thing is that it is fairly well standardized: you can jump into another airplane, look around for a few minutes, and know roughly where everything is and how to operate it. Even without much (any?) experience, you can probably find all the same instruments in roughly the same place in &lt;a href=&quot;https://i.stack.imgur.com/jc3Db.jpg&quot;&gt;this slightly more robust panel&lt;/a&gt; - the biggest difference being that there are &quot;control yokes&quot; instead of sticks, and the addition of a few navigation radios and instruments. Even &lt;a href=&quot;https://i.stack.imgur.com/dX2WR.jpg&quot;&gt;this DC-3 panel&lt;/a&gt; has a strong similarity to the first panel above, even though it's a much more complex aircraft. (The &lt;a href=&quot;http://www.deviantart.com/art/DC-3-Cockpit-N44V-209541779&quot;&gt;original DC-3 panel image is here&lt;/a&gt; - click through and check out the full-size version, you can read all the labels).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that regard the layout of an aircraft panel is similar to a car's dashboard: You can drive in a Ford Mustang your whole life (the first panel), but if you sat down in a BMW 5-series the controls and instruments would be familiar to you (the second panel). If someone dropped you in a snow plow (the DC-3 panel) you may take a few minutes to look around and make sure you know where everything is, but you will be able to pick out the basic controls and gauges and know what they all do (which by no means implies you could handle driving the snow plow and more than I could handle flying a DC-3, simply that a lot of the knowledge transfers).  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I've ignored &quot;glass panel&quot; aircraft in this discussion, but if you look at a bunch if them you'll find that they all have a similar layout (a large artificial horizon with &quot;tapes&quot; showing airspeed, altitude, and heading). &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-03-29T21:29:52.570" LastActivityDate="2014-03-29T21:29:52.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2879" PostTypeId="2" ParentId="2873" CreationDate="2014-03-29T21:22:10.950" Score="30" Body="&lt;p&gt;There’s quite a difference in designing a user interface for a first-time user compared to an expert. Much of airplane design is only for experts, and the designers are willing to have a steep learning curve if it improves efficiency, ease, and safety once someone is experienced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I’d also note:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fewer controls doesn’t mean easier. In a car, for example, a touch-screen display can be much more annoying than a nice set of knobs.&lt;/li&gt;&#xA;&lt;li&gt;Habits can be formed more easily with different kinds of controls and locations. Designers often deliberately make different controls look and feel different. You don’t want to confuse a gear knob and a flaps knob, for example, so they have different shapes. This can seem overly confusing at first, but really helps build muscle memory.&lt;/li&gt;&#xA;&lt;li&gt;The location of the controls itself can be very significant. The knobs and switches on the ceiling are likely to be less commonly-used and thus don’t need to be in the direct line of sight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="639" LastActivityDate="2014-03-29T21:22:10.950" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2880" PostTypeId="2" ParentId="2873" CreationDate="2014-03-29T21:54:12.160" Score="8" Body="&lt;p&gt;There is not a single, uniform, design philosophy, for airplane cockpits. The cockpit is a &quot;user interface&quot;. Some are easy to use. Others are powerful but confusing for beginners. Some implement standards so that knowledge of one can be applied with any. Some are hodgepodges with no consistency within themselves. Some start with an expresable goal but fail to acheave it. Some are utilitarian objects with controls and indicators in a regular pattern or patterns without regard for how they are comprehended or operated. In many cases, one intent at the beginning of design is merged with other ideals, requirements, informal norms and the like. Cheap and simple to build, and easy to maintain for decades, are as real as imperatives as any other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a modern Boeing transport, pilot and copilot each have a semicircular 'wheel' that turns left and right, to deflect the ailerons and regulate rate of roll. The wheel is pulled back or pushed forward to deflect the elevators, which control the angle of attack of the airplane's wing, and thus, taking engine thrust into account, the vehicles's speed, if allowed to stabilize. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wheels and columns carrying them are interconnected, so moving one control moves the other. Unless some mechanical mishap has locked one in place, in which case an intentionally breakable link can be broken, by force, allowing them to move independently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the same physical object produces two different kinds of effect, one a rate, with zero near the middle, one, a position, which physics causes to control a rate, with zero beyond one extreme, (speed) not intuitively linked to it. Speed is &#xA;also, very strongly, influenced by the engines' throttle position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a modern Airbus transport, a one-hand handle off on the outside of each seat pivots at it's base, seeming to &quot;point&quot; the airplane this way or that, but physics still separates the effect of roll, a rate, from the effect of pitch, a position, which, at equilibrium control speed, a rete, but not the intuitively obvious one. However, the captain's handle doesn't move the copilot's handle, so there's no visual or tactile link between the position of one control and the other. If each is moved in the opposite sense of the other, the result is zero roll rate and zero pitch angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a General Dynamics (now Lockheed) F-16, there is a one-hand handle to the right of the pilot's seat, which does not move (in any significant way) but senses the direction the pilot is pushing it and moves the same control surfaces to accomplish the same pitch and roll control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When 'blind' flying instruments for night and bad weather were invented, the authorities in Great Britain specified that all airplanes bought by the British government would have their blind flying instruments in a standard 2 rows by 3 columns layout. When deHavilland designed the Mosquito, the world's fastest production fighter-bomber at that time, they designed the instrument panel by mounting some other airplane's panel in the middle and adding additional switches, dials, etc, on additional panels left, right and below the &quot;basic 6&quot;. The 'borrowed' panel is curved at the top to match the top of some fuselage, but not a Mosquito. Every Mosquito built has a panel with that same, mis-matched, curve. Kinda funny, once you know to look for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cultural norms play a large role too. The USAF studied moving tape/fixed pointer indicators in the 1960s, concluded that pilots could operate more accurately with them than &quot;steam gauge&quot; round instruments. But they cost more because of smaller volumes, more moving parts, they don't fit in a simple, round hole in the panel, and they're &quot;different&quot;. Modern glass cockpits mix simulated moving tapes with fixed needles and simulated dials with moving needles. The instruments for some of SpaceShip One's cockpit were horizontal graphics on a laptop computer, which may have been time histories with vertical amplitudes...&lt;/p&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="1897" LastEditDate="2018-02-24T01:00:56.243" LastActivityDate="2018-02-24T01:00:56.243" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2881" PostTypeId="2" ParentId="2861" CreationDate="2014-03-29T22:39:05.737" Score="3" Body="&lt;p&gt;The major requirement for dental fillings as far as aviation (or diving) is concerned is there not be a trapped air pocket under the filling (this could cause problems for divers or pilots as the pressure changes may cause discomfort. (It's called &lt;a href=&quot;http://en.wikipedia.org/wiki/Barodontalgia&quot; rel=&quot;nofollow&quot;&gt;barodontalgia&lt;/a&gt; - pressure-induced tooth pain.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air pockets are something your dentist will try to avoid anyway because they promote further decay &amp;amp; will eventually require more work on the tooth, so if your dentist is competent you shouldn't have any problems.&lt;br&gt;&#xA;If you do notice discomfort while flying mention it to your dentist - an X-Ray can usually identify the problem in a few minutes, and your dentist can then take care of it (replace the filling, or if it's a new cavity treat it appropriately).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-03-29T22:39:05.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2882" PostTypeId="2" ParentId="2873" CreationDate="2014-03-30T00:09:08.167" Score="67" Body="&lt;p&gt;As has been pointed out in a previous answer, the cockpit is a user interface. My belief is that it is virtually impossible to design any user interface that is user-friendly to both novice and experienced users, and I question whether you would really even want to do that. For example, in a light single engine aircraft with one fuel tank, a single on/off switch for fuel is understandable for the novice and adequate for the experienced. That same airplane might not have a hydraulic system so there is no need for hydraulic controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider an airplane with nine fuel tanks, four hydraulic systems, and eight hydraulic pumps. Possibly you could engineer it such that when everything is working, a single on/off switch for fuel and another for hydraulics would work. However, if you're over an ocean with 400+ souls on board, you need more than everything is working fine or everything is not working fine. You need the ability to keep part of the systems working even when part of them have failed, and for that you need information on each component and the ability to control and/or isolate each component, not to mention understanding the components and how they work together, and how the failure of one can impact the failure of another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be unreasonable to expect a novice to deal with failures of individual system components, and it would be irresponsible to put a novice in charge of such a situation. Thus, right off the bat, we can and should dispense with trying to make the system user-friendly to the novice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, we might have a system that seems incomprehensible to the novice, but it is and feels to be the right complexity to the person working with it on a daily basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first airplane I regularly flew as a licensed pilot was a Cessna 150. It quickly became the right size. I decided one day I wanted to check out in a Cessna 172, and that airplane was a &quot;big airplane&quot; for the first flight or two. When I checked out in a 182, I had the complication of a propeller control and a manifold pressure gauge. Hmm, did I really need that? Through the years the airplanes got bigger, but I found that I came to regard the airplane that I was flying as just the right size and no more complicated than it needed be for the task at hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When they used a 747 to transport a single passenger, the movie star Rock Hudson, back to the U.S. when he collapsed in Paris, I didn't think that strange. It was just an airplane, and the 747 was that airplane that was the right size for me.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-03-30T01:04:45.410" LastActivityDate="2014-03-30T01:04:45.410" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="2883" PostTypeId="1" CreationDate="2014-03-30T01:39:27.603" Score="16" ViewCount="5291" Body="&lt;p&gt;Couldn't you just generate lift with a long body? Maybe a little broader than a normal plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a design enhancement, we would need  a heavier bottom, so the plane doesn't flips to a side. &lt;/p&gt;&#xA;" OwnerUserId="914" LastActivityDate="2016-09-13T14:48:14.867" Title="Do airplanes need wings?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="5" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2884" PostTypeId="2" ParentId="2873" CreationDate="2014-03-30T01:50:19.747" Score="168" Body="&lt;p&gt;I would argue that the controls of an aircraft are &lt;strong&gt;not&lt;/strong&gt; complicated, but rather that they are simply foreign to you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the vast majority of cases, the various controls in the aircraft do one thing:  Turn something on, or turn it off.  They are quite simple actually, but what makes it appear complicated to you is that there are so many of them.  As you learn about the airplane (especially modern ones) you will see that these individual controls are grouped together by system, in a way that actually makes pretty good sense.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To put it in perspective, let's say that you had never seen a laptop computer before:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zll9U.jpg&quot; alt=&quot;laptop&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This...  &lt;strong&gt;thing&lt;/strong&gt; (remember, you've never seen one before!) has 94 buttons on the top alone!  It has all kinds of little jacks and plugs on the outside.  It has things that pop open from the side.  It's just...  &lt;strong&gt;&lt;em&gt;complicated&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then someone points out that most of the buttons on the top are buttons that you can press to make a letter show up on the screen.  This takes much of the mystery out of the complicated mess on the top, but then as you start to learn more you figure out that some of the less commonly keys are grouped together by function.  You have the arrow keys, the function keys, the key modifiers, the CD controls...  Suddenly it doesn't seem quite so complicated anymore.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You complain to your friend that the monitor (hey, we've learned a fancy new word!) is a little too small, and they suggest that you hook up an external monitor.  We can do that??  Of course, that's what this port is for.  Cool, now that's one less mystery.  This goes on, and before long you can even pick up a different brand of laptop, with different buttons and pretty much figure it out on your own.  Before long...  the mystery is gone and it's just a laptop computer.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;And so it goes with airplanes.  Newer airplanes are being designed with fewer switches and gauges.  Take a look at the progression in the Falcon 900 series aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.helicopterbusinessindex.com/aircraftPictures/aircraft/14291-0-306607.JPG&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iTJri.jpg&quot; alt=&quot;Falcon 900B&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;strong&gt;Falcon 900B&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.atlaviation.com/wp-content/uploads/2010/10/View2_1200x800.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kHEDz.jpg&quot; alt=&quot;Falcon 900EX&quot;&gt;&lt;/a&gt; &#xA;&lt;strong&gt;Falcon 900EX&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.amjetexecutive.com/uploads/tx_cimdiaporama/11-general-flotte-900ex5.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HQpFh.jpg&quot; alt=&quot;Falcon 900EZ&quot;&gt;&lt;/a&gt;&#xA;&lt;strong&gt;Falcon 900EX-EASy&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each iteration has fewer and fewer controls and instruments.  You may even say that they look less complicated.  However, I can assure you that each newer model has far more capabilities and a lot more to learn in order to understand and safely fly the airplane.  They each have the full capability of the model before it, along with additional features and more to learn.  Certain systems no longer have switches or dials and you have to look through different menus in order to access them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appearances... can be deceiving.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-03-31T14:11:53.110" LastActivityDate="2014-03-31T14:11:53.110" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2885" PostTypeId="2" ParentId="2883" CreationDate="2014-03-30T01:54:17.247" Score="14" Body="&lt;p&gt;Yes you can, these are called &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting_body&quot;&gt;lifting bodies&lt;/a&gt;, they are not very efficient and require a lot of speed before they generate enough lift to stay aloft, requiring a long runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/1983_Negev_mid-air_collision&quot;&gt;In 1983 a F-15 fighter lost a wing&lt;/a&gt; in a mid air collision and was able to land safely due in part by the main body being able to generate enough lift for the plane to stay controllable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are only really useful for supersonic flight where normal wings create too much drag&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-03-30T01:54:17.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2886" PostTypeId="2" ParentId="2883" CreationDate="2014-03-30T02:50:45.750" Score="10" Body="&lt;p&gt;There are indeed &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-011-DFRC.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;lifting bodies&lt;/a&gt; which were able to fly without wings. But wings are much better at creating lift than a bulky fuselage. The space shuttle was developed based on testing lifting bodies, which allows it to have fairly small wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you are describing sounds a bit like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Blended_wing_body&quot; rel=&quot;nofollow noreferrer&quot;&gt;blended-wing-body&lt;/a&gt; (BWB), which smoothly integrates the fuselage with the wing. Sort of like a commercial version of the B-2 flying wing design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fMmA5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is certainly still in the concept phase. Boeing has flown a scale model to test the concept, and it has performed well. Aside from being more efficient than traditional designs, it can also produce much less noise if the engines are positioned above the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have about 100 years of development in the traditional airplane design, which contributes to the efficiency and safety that we are able to achieve right now. Going with a BWB design alters so many of the standard design features that this presents a very radical change. When the benefits start to outweigh the costs of moving to this design, we may start to see more planes like this.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-03-30T02:50:45.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2887" PostTypeId="1" AcceptedAnswerId="2888" CreationDate="2014-03-30T02:57:12.300" Score="35" ViewCount="36950" Body="&lt;p&gt;Why don't they just say 'people' on board, why souls? What is the origin of this term? I'm thinking it comes from sailing as I think I've heard that term in reference to crews out at sea, but I'm not a sailor so I don't know.&lt;/p&gt;&#xA;" OwnerUserId="1505" LastActivityDate="2019-02-17T17:29:38.553" Title="Why is the total count of people on a plane given as the number of 'souls' on board?" Tags="&lt;phraseology&gt;" AnswerCount="7" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2888" PostTypeId="2" ParentId="2887" CreationDate="2014-03-30T03:13:17.743" Score="45" Body="&lt;p&gt;The primary reason is probably that it ensures there is no confusion between passengers, crew, or infants. Technically, &quot;passengers&quot; is the number of seats occupied, &quot;crew&quot; is both the pilots and flight attendants on duty. So any small children brought on as &quot;lap children&quot; will not be included in the &quot;passengers&quot; count, but should be included in the total number of people on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found another interesting point &lt;a href=&quot;https://english.stackexchange.com/q/39522/42179&quot;&gt;over on the English Stack Exchange site&lt;/a&gt;, which is that dead bodies are sometimes transported as well. In this case, some might consider these &quot;people&quot; as well. Also, in an incident, the bodies should not be confused with the regular passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &quot;souls&quot; effectively communicates the number of living humans on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may certainly be holdovers from the maritime influences on aviation as well.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:38:46.017" LastActivityDate="2014-03-30T23:00:10.977" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2889" PostTypeId="2" ParentId="2887" CreationDate="2014-03-30T03:53:45.493" Score="13" Body="&lt;p&gt;The earliest reference I can find to 'souls' as a count of persons is mid-eighteenth century, although it probably was in use earlier. It appears in maritime commerce, as the number of living humans aboard a ship, and in civics, as the population of a town or city.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that in the early 1700s the words 'people' and 'person' both had strong connotations compared to those words today. 'People' meant humans of a certain country or a specific culture, and 'persons' meant humans of note or important characters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I conclude that a need arose, driven by government and commerce, for a word to mean an unaffected and precise head count, that yet afforded those being counted a little more respect than the barrels, boxes, coins, and cows whose numbers were also tallied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if I could find a reference to that usage of 'souls' from the thirteenth or fourteenth century, I would simply assume that it arose from the learned churchmen who were doing the counting, as literacy was not yet widespread.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-03-30T03:53:45.493" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2890" PostTypeId="1" CreationDate="2014-03-30T04:57:17.203" Score="12" ViewCount="5901" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;You may be surprised to find out that an airplane can stall at any attitude if the critical angle of attack is exceeded, but it cannot stall at 0 G.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This quote found in the &lt;a href=&quot;http://www.flightresearch.com/pdfs/FLY0414_Upset_in_a_Bizjet.pdf&quot;&gt;April 2014 issue of &lt;em&gt;Flying&lt;/em&gt; magazine&lt;/a&gt;, but it seems counterintuitive to me.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why can't an airplane stall at 0G?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="97" LastEditDate="2015-03-20T13:58:48.880" LastActivityDate="2017-05-14T00:23:37.227" Title="Why can't an airplane stall at zero G?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;&lt;g-forces&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2891" PostTypeId="2" ParentId="2890" CreationDate="2014-03-30T05:07:36.643" Score="16" Body="&lt;p&gt;At 0 G the plane does not need to generate any lift, therefore there is no critical angle past which the airfoil cannot generate the lift required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, a sustained 0 G maneuver is a parabolic arc, which means that in theory your flight path should keep your angle of attack at zero the entire time (in a theoretical, symmetrical airfoiled aicraft). You can't stall because your AoA is constantly 0 degrees and cannot exceed the critical angle.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="-1" LastEditDate="2017-05-14T00:23:37.227" LastActivityDate="2017-05-14T00:23:37.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2892" PostTypeId="2" ParentId="2822" CreationDate="2014-03-30T06:42:10.517" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://www.google.com/maps/@27.7630431,-82.6250911,1582m/data=!3m1!1e3&quot; rel=&quot;nofollow&quot;&gt;Here is Albert Whitted Airport&lt;/a&gt;, a GA facility in St. Petersburg, FL, which has actually juts out into Tampa Bay.&lt;/p&gt;&#xA;" OwnerUserId="1905" LastEditorUserId="19" LastEditDate="2016-07-05T06:43:12.333" LastActivityDate="2016-07-05T06:43:12.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2893" PostTypeId="2" ParentId="2890" CreationDate="2014-03-30T09:25:55.887" Score="7" Body="&lt;p&gt;Look at it backwards. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why are you at zero G? Because your downward acceleration is equal to&#xA;the acceleration due to gravity.&lt;/li&gt;&#xA;&lt;li&gt;Why are you accelerating downwards so fast? Because you're not creating any lift to counteract gravity.&lt;/li&gt;&#xA;&lt;li&gt;Why are you not creating any lift? Because you are at zero degrees angle of attack!&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And &lt;em&gt;that's&lt;/em&gt; why you can't stall at zero G. You're always also at zero degrees angle of attack (you can get pedantic, depending how you measure it) when you're at zero G. And stalling is always caused by high angles of attack. And if that doesn't make 100% sense, you should look more into stalls before you dig too deep into how G loading affects stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Many people here seem to be replacing the world &quot;airplane&quot; in the question with the word &quot;wing&quot;. 0g flight involves the entire airplane, not just the wing. Sure, you could take a Cessna, strap highly controllable rocket engines to the top of it and drop it from another airplane. Then, use the rocket engines to counteract drag and give downward acceleration equal to the force of gravity. That would give you a stalled wing and 0g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;But that's not really an airplane anymore, and it doesn't really answer the question.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To stall, the wing must exceed the critical angle of attack. That means it must have an angle of attack above zero. That means lift is being created, which means an upward force is acting upon the airplane. That means you are no longer at 0g. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point isn't that once an airplane is at 0g it becomes unstallable. The point is you have to leave 0g to stall it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also an example of how airspeed is irrelevant to stalling. (Sounds crazy, since we talk about stalling speed!) Stalling isn't about the speed or amount of air flowing over the wings, it's about the angle, path and flow. A wing on the same airplane can be not stalled at 5mph, or stalled at 100mph. It just depends on the angle.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastEditorUserId="1900" LastEditDate="2014-03-30T22:15:21.167" LastActivityDate="2014-03-30T22:15:21.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2894" PostTypeId="2" ParentId="2850" CreationDate="2014-03-30T09:40:14.123" Score="5" Body="&lt;p&gt;General American law: it's legal if it ain't illegal. And there's no overarching law that covers all RC airplanes. So the law is you can fly them except where you can't. That may sound unhelpful, but my point is that unless where you are has specific laws or rules against it, you're fine. There's also a general restriction on commercial use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What many people don't know about is Temporary Flight Restrictions(TFRs). TFRs happen all over the country for all sorts of reasons, and they are just what they sound like: a temporary restriction on flying over a certain area. They could be for wildfires, or large events, or VIPs. When the President of the US travels, there is usually a 30 mile radius TFR put up around the area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I bring this up is these TFRs almost always include &quot;no RC airplanes&quot; as a restriction. So the President visits a city 25 miles away, you fly your RC airplane in your backyard, and you're technically breaking federal law.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-03-30T09:40:14.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2895" PostTypeId="2" ParentId="2890" CreationDate="2014-03-30T11:16:17.147" Score="13" Body="&lt;p&gt;It's probably more accurate to say &quot;you cannot maintain 0 G in a stall&quot;. Even a stalled airfoil generates &lt;em&gt;some&lt;/em&gt; lift -- the stall just means that the lift coefficient drops below the best the airfoil can do, not that it becomes zero. Since the stalled wing produces lift, and this lift is generally not in a direction where it can be canceled out by thrust, it will pull the aircraft away from the freefall trajectory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And even that isn't completely true in the theoretical extreme. If we imagine an aircraft with fully variable angle of incidence (never mind the engineering problems in building such a thing), we can imagine rotating the wings up to around 90° angle of attack. Then, by symmetry, they will not produce any lift, yet it will be fully stalled. There will be lots and lots of drag, but sufficiently powerful thrust can offset that and make the net motion of the aircraft follow a zero G / freefall trajectory.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-03-30T11:16:17.147" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2896" PostTypeId="2" ParentId="2887" CreationDate="2014-03-30T13:13:35.280" Score="20" Body="&lt;p&gt;I agree with &lt;a href=&quot;https://aviation.stackexchange.com/a/2888&quot;&gt;what fooot said&lt;/a&gt;.  Also, I would add, as someone to volunteers in search &amp;amp; rescue (Civil Air Patrol) as a mission pilot, when you hear the word &quot;souls,&quot; it adds some urgency and seriousness to the handling of any emergency.  When an air traffic controller asks a pilot, during an emergency, for the number of souls on board, it communicates to the pilot that the controller and pilot are focusing extra hard together on solving the emergency successfully, and that one word tells the pilot that the controller is going to be marshalling resources to help in every way possible.  &quot;Souls&quot; is a term full of life and caring.  For rescuers, it communicates very quickly the &lt;strong&gt;total&lt;/strong&gt; number of persons who must be found and saved.&lt;/p&gt;&#xA;" OwnerUserId="1912" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-04-04T07:09:25.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2897" PostTypeId="2" ParentId="2890" CreationDate="2014-03-30T14:19:29.447" Score="6" Body="&lt;p&gt;&lt;em&gt;Critical angle of attack&lt;/em&gt; or &lt;em&gt;stall angle of attack&lt;/em&gt; is &lt;strong&gt;by definition&lt;/strong&gt; the maximum angle at which the stream over the airfoil is still attached. It is also the angle of maximum lift. Beyond this angle, the stream over the airfoil becomes unattached, leading to a &lt;em&gt;sudden decrease in lift&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fo9cb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I think the article is somehow misleading. I think what they mean by &lt;em&gt;stall&lt;/em&gt; is the airplane lift not being able to compensate weight. Since the weight in 0G is 0, then obviously it won't &quot;stall&quot; in this definition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A harder question is whether the airfoil can stall in 0G according to the actual definition. Well, if the airplane is free falling in a straight line with its wings parallel to the ground, the airfoil is stalling, but in reality it will likely enter spiral dive, the airfoil will produce lift (which produces the centripetal force of the spiral) and won't be 0G anymore. An airplane is so that it will naturally adapt to the relative air stream, so it's hard to maintain 0G. You do this following a ballistic trajectory, on which at the top portion of the trajectory you get a short free fall feeling, where the airfoil is not producing lift (zero angle of attack).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source: &#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Low-g_condition&quot; rel=&quot;noreferrer&quot;&gt;http://en.wikipedia.org/wiki/Low-g_condition&lt;/a&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Angle_of_attack#Critical_angle_of_attack&quot; rel=&quot;noreferrer&quot;&gt;http://en.wikipedia.org/wiki/Angle_of_attack#Critical_angle_of_attack&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1913" LastEditorUserId="1913" LastEditDate="2014-03-30T14:25:35.267" LastActivityDate="2014-03-30T14:25:35.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2898" PostTypeId="2" ParentId="2354" CreationDate="2014-03-30T15:11:37.070" Score="11" Body="&lt;p&gt;Another minor reason is that white color protects from adverse radiation better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In regards to nuclear bombers this is called '&lt;a href=&quot;https://en.wikipedia.org/wiki/Anti-flash_white&quot;&gt;anti flash white&lt;/a&gt;', though regular planes flying at high altitudes supposedly benefit from this as well.&lt;/p&gt;&#xA;" OwnerUserId="1915" LastActivityDate="2014-03-30T15:11:37.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2899" PostTypeId="1" AcceptedAnswerId="2900" CreationDate="2014-03-30T19:14:58.933" Score="17" ViewCount="20651" Body="&lt;p&gt;All I know from Google searching is that they provide hearing protection and ATC communication maybe? Do pilots have to attach them or are they wireless? Who can the pilot reach using them?  How much hearing protection does a pilot need? For instance, how does a pilot figure out how many decibels of protection is needed say for a Cessna 172? Must headsets always be worn? I'm interested in knowing all aspects of the uses of an aviation headset.&lt;/p&gt;&#xA;" OwnerUserId="870" LastEditorUserId="870" LastEditDate="2014-03-30T21:49:26.893" LastActivityDate="2017-02-05T17:52:53.130" Title="What exactly are the functions of an aviation headset?" Tags="&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2900" PostTypeId="2" ParentId="2899" CreationDate="2014-03-30T21:39:46.430" Score="21" Body="&lt;p&gt;Aviation headsets are just like gaming headsets on a computer or console gaming system, except they are sturdier and much more expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the basic end of the spectrum, an aviation headset is just a big clamp style pair of around the ear headphones with a microphone.  The cable from the headset has 2 plugs (for airplanes) or one plug (for helicopters).  These two plug styles are equivalent electronically, with the helicopter cable having an extra conductor in order to include the microphone and headphones in the same plug. The two-plug variant has one plug for the headphones and one of the microphone.  These differ from gaming headsets in that the headphone plug is 0.25&quot; (the kind a nice stereo receiver uses) and the microphone plug is 0.206&quot;.  This difference in sizes is to avoid mixing up which plug goes in which jack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation headsets fall into two broad categories: passive noise reduction and active noise reduction (ANR).  The passive noise reduction headsets rely on a good seal around the ear and a strong clamping force (e.g. David Clarks).  Active noise reduction are somewhat less &quot;clampy&quot; and provide less passive protection but make up for this with the active protection.  An ANR headset is money well spent, but these do top out at around \$850-\$1000 for the top models from Lightspeed and Bose respectively.  ANR headsets must be powered to work properly but all ANR headsets still function without power as passive noise reducing headsets.  Power for an ANR headset can come from a battery box or from aircraft power but not interchangeably.  Aircraft power requires panel installation of a plug specific to the headset brand (a single connector provides power, headphone and microphone connections).  In general, unless you happen to own an airplane and install the power plug, you should get the battery version of a headset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary purpose of these headsets is to reduce the noise in the cockpit (they can be very loud) in order to avoid hearing loss (yes, it is that loud) and to facilitate clearer communication with ATC.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For quieter airplanes there are in-ear headsets that have more in common with earbuds than the bigger headsets.  Some of these are just earplugs wired for sound and some use molds of your ear to provide the seal.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The headset is connected to the airplanes audio panel.  Audio panels vary in complexity but their basic job is to provide an intercom for communication between occupants of the airplane and access to the com radio for communication with ATC.  The audio panel is also able to monitor (listen) the navigation radios certain types of beacons.  In transport aircraft the audio panel is also tied into the passenger address system and the flight attendant's phones in the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The headsets can be operated in a hot mic setup or the mic can be explicitly turned on and off.  The hot mic is the usual method and the audio panel provides a squelch control so you aren't broadcasting the cockpit noise when not talking.  The ATC transmissions are via a push-to-talk (PTT) switch.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aviation headsets for the most part do not need to be approved to use in airplanes, but in some situations for US registered aircraft, the requirement of an approved headset can be mandated (some (all?) 121 carriers).  The FAA standards for approval are specified in TSO C-57a and C-58a.  You'll find many, but certainly not all, aviation headsets conform to these orders.  They define minimum performance characteristics of the electronics, speakers, microphones, etc that make up the headset.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;How much hearing protection is needed depends greatly on the specific airplane in question.  Jets can be on the very loud end of the spectrum (EMB-145) or they can be quiet enough that even passive noise reduction is largely unnecessary.  For the noisy end of the spectrum peak wavelengths can be well in excess of 100 dB.  I can find reports of 130 db in some smaller airplanes and reports of 84 db in a 737 during cruise, but these numbers are all anecdotal in nature.  What is important to take from these is not the specific numbers but that they are high enough to cause hearing loss during prolonged exposure.  The National Institute on Deafness and Other Communication Disorders defines 85 dB as the threshold for hearing damage from long or repeated exposure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passive headsets generally advertise noise reduction around 20 dB (23 dB for the venerable David Clarks) and some people will wear earplugs under a headset to further increase the passive noise reduction. A cursory look at ANR headsets reveal that they tend not to advertise their performance and instead specify maximum ambient noise levels for ANR to properly function (around 120-125 dB for Bose and Lightspeed headsets).  I can personally add an anecdote that both the Lightspeed Zulu and Bose X make dramatic changes in noise level (both of these headsets are now outdated and replaced by newer versions).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most smaller airplanes you will wear the headset from startup to shutdown.  As you get into the large jets I have observed crews that wear minimal headsets during takeoff and landing, but not always during cruise.  These airplanes were quiet enough that they were not needed.  On turboprops and smaller jets that I have been in, headsets were worn throughout the flight.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On newer ANR headsets in particular you will find some extra features beyond just being a pair of headphones and a microphone.  These extras include a 3.5 mm auxiliary jack to connect external music and bluetooth to connect your phone or other device to the headset.  These typically come with circuitry to automatically mute or greatly decrease the volume of these inputs when ATC is transmitting.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="72" LastEditDate="2014-04-23T12:45:46.997" LastActivityDate="2014-04-23T12:45:46.997" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="2901" PostTypeId="2" ParentId="2899" CreationDate="2014-03-30T21:40:24.563" Score="4" Body="&lt;p&gt;An &quot;aviation&quot; headset is really not much more than an expensive set of headphones with a microphone. They do not do any radio communication by themselves, but are plugged into the aircraft radio system. There are wireless aviation headsets, but many pilots will likely prefer wired ones because there are fewer things that can go wrong (for example, you need to keep the batteries in a wireless headset sufficiently charged for your flight). You would still need to plug part of a wireless headset (not the part you wear) into the aircraft radio system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Headsets are not technically required equipment, but small aircraft cockpits are pretty noisy so hearing protection is a comfort issue for the pilot (and passengers). Depending on where the pilot intends to fly, the ability to communicate by radio may be required (for example, through controlled airspace near an airport).&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-30T21:40:24.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2902" PostTypeId="1" AcceptedAnswerId="2939" CreationDate="2014-03-31T00:01:31.590" Score="14" ViewCount="767" Body="&lt;p&gt;I saw various people talking about volunteering with CAP. I’m about to sit my test for my PPL, and am wondering whether there are opportunities to volunteer for search and rescue, or more generally, am interested to hear what is involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I’m in the San Francisco Bay area, if anyone has specific local content as well.)&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="12220" LastEditDate="2016-03-28T12:27:10.223" LastActivityDate="2016-03-28T12:27:10.223" Title="What is it like to volunteer with Civil Air Patrol (CAP) as a pilot?" Tags="&lt;usa&gt;&lt;search-and-rescue&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2903" PostTypeId="1" AcceptedAnswerId="2905" CreationDate="2014-03-31T00:07:40.977" Score="35" ViewCount="17816" Body="&lt;p&gt;Everyone says that the angle of attack is what determines a stall, not the speed. I understand the theory and understand that it is separation of the airflow that matters for stalling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I don’t understand in a practical sense. Let’s say you’re in a Citabria going at 100 knots. If you pull up extremely fast, you can get a high angle of attack, beyond what you’d need to stall at 60 knots, yet you wouldn’t stall straight away. If you stayed at that angle of attack, you’d quickly slow, then stall. But if I’m right that you wouldn’t stall straight away, then it seems like the angle of attack is not the only thing that matters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I missing? What’s wrong in my argument?&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="1696" LastEditDate="2015-02-19T21:50:42.650" LastActivityDate="2019-03-31T20:42:21.857" Title="How does stall depend on angle of attack but not speed?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="8" CommentCount="8" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2904" PostTypeId="2" ParentId="2903" CreationDate="2014-03-31T00:43:21.543" Score="13" Body="&lt;p&gt;It's funny you mention a Citabria, because I've actually done &lt;em&gt;exactly&lt;/em&gt; what you're talking about that in &lt;em&gt;exactly&lt;/em&gt; that airplane. Not that it really matters, because this will apply in any airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your question, you said that you understand angle of attack is what causes the stall. But I'm not sure that you understand that given the same wing, it's always the same angle. I say that because of this: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;you can get a high angle of attack, beyond what you’d need to stall at 60 knots, &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The angle of attack you need to stall remains the same, regardless of speed. Perhaps things are different in the supersonic realm, but this is good enough for Citabrias.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're right that if you were cruising at 100kts and suddenly pulled back on the stick, you would slow down before stalling. But that's not what causes the stall. The stall is caused by high angle of attack, and that's caused by elevator position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stick position is the single best predictor of when an airplane will stall, and nobody talks much about it. I can also say your example isn't 100% accurate, because I've actually done it. If you cruise at 100kts, then slam the stick back as hard as you can, you'll stall with a minimal loss of speed beforehand. And if you wanted, you could have a higher entry speed than 100kts and stall at 100kts. Eventually, you get into structural issues caused by the excessive g-loading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stalling isn't just caused by angle of attack, it's always caused by the &lt;em&gt;same&lt;/em&gt; angle of attack. I hope this answers your question.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-03-31T00:43:21.543" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2905" PostTypeId="2" ParentId="2903" CreationDate="2014-03-31T01:15:07.637" Score="44" Body="&lt;p&gt;I believe you are confusing the wing angle of attack with the pitch of the aircraft.  Aircraft moving at a slow, near-stall speed, despite pointing the nose up, will still be traveling more or less horizontally.  Their VSI instrument will read near zero.  Whereas, if you take an aircraft moving quickly and pull the nose up to the same angle, the aircraft will, obviously, climb rapidly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does this matter?  The angle of attack is defined based on the wing's motion through the relative wind.  The wing's orientation relative to the ground isn't involved in the definition in any way.  When the aircraft as a whole is climbing, the relative wind is coming down from above.  As a result the angle of attack is reduced, compared to what it would be if the plane were not climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to show some quick numbers, suppose you took an aircraft moving at 100 kts in still air and pulled the nose up so that you are now climbing at 3,000 FPM (most aircraft will lose speed doing this, but the math is valid until the airplane slows down).  $1knot\approx100FPM$, so you'll now have an upward vector of 30 knots.  Your 100 kt airspeed is now moving up at an angle.  A little trigonometry:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\sin(x)=\frac{30}{100}$$&#xA;$$x=17.46°$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, your angle of attack is 17.46 degrees farther away from stalling when climbing at 3000FPM than it would be if your aircraft had the same pitch but was in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, few aircraft have the engine power to sustain a climb at this rate.  The aircraft will bleed off speed, and as the speed bleeds off, the aircraft will slow, the climb rate will decrease, the aircraft's velocity will become closer to horizontal, and, eventually, the aircraft will stall if the pitch is held constant.&lt;/p&gt;&#xA;" OwnerUserId="1027" LastEditorUserId="97" LastEditDate="2014-04-17T02:25:47.410" LastActivityDate="2014-04-17T02:25:47.410" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2906" PostTypeId="2" ParentId="2887" CreationDate="2014-03-31T01:18:53.287" Score="2" Body="&lt;p&gt;Aircraft (and previously, ships or trains) are frequently used to transport casketed remains en route to funeral. &quot;Souls&quot; was devised to remove any ambiguity about which &quot;passengers&quot; were among the living.&lt;/p&gt;&#xA;" OwnerUserId="1926" LastActivityDate="2014-03-31T01:18:53.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2907" PostTypeId="1" CreationDate="2014-03-31T02:33:57.440" Score="8" ViewCount="2714" Body="&lt;p&gt;When the transponder on Malaysia Airlines Flight 370 went off, there was no ALARM. The satellite kept getting pings, and apparently &quot;knew&quot; that the transponder was off. Would it not be a great idea if the Malaysia Airlines got an alarm indication that the transponder was off on one of their planes? The airline could have radioed the pilot and asked what the trouble was. If the pilots did not respond, some jets could have been scrambled to checkout what is going on. The scrambled jets could have followed the airliner for hours and watched them crash in the ocean, when they ran out of fuel. We would know EXACTLY where the airline crashed!&lt;/p&gt;&#xA;" OwnerUserId="1927" LastEditorUserId="69" LastEditDate="2014-03-31T12:51:04.140" LastActivityDate="2015-02-04T22:43:43.933" Title="Why is there no alarm when the transponder is turned off?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;emergency&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2908" PostTypeId="2" ParentId="2907" CreationDate="2014-03-31T03:38:28.243" Score="24" Body="&lt;h2&gt;Because it's not worth it.&lt;/h2&gt;&#xA;&lt;p&gt;Quick, name me &lt;em&gt;another&lt;/em&gt; accident where a transponder-off alarm would have been exactly what was necessary to save the crew, the passengers, or the airframe?&lt;/p&gt;&#xA;&lt;p&gt;Hint: there aren't many.&lt;/p&gt;&#xA;&lt;p&gt;The number of false positives would &lt;em&gt;drastically&lt;/em&gt; outweigh the number of actual events where a transponder alarm would have been able to do some good.  For example, air traffic control might ask an aircraft to turn off their transponder.  Nothing dangerous there, but alarms would be going off back at dispatch.  &lt;strong&gt;Good idea on paper, but not practical enough to make it worthwhile in the real world.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-31T03:38:28.243" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2909" PostTypeId="2" ParentId="2907" CreationDate="2014-03-31T03:40:10.990" Score="13" Body="&lt;p&gt;Turning off the transponder, radio, flight recorder, engine, air conditioning, lavatory or any of the other things on the Minimum Equipment List does not usually qualify as an emergency. There are spares which can be switched on as soon as deemed prudent. If the pilots have something to say, they will. If they can't, they probably have more important things to do. Aviate, Navigate, Communicate. In that order. &lt;/p&gt;&#xA;" OwnerUserId="1928" LastActivityDate="2014-03-31T03:40:10.990" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2910" PostTypeId="1" CreationDate="2014-03-31T05:21:35.287" Score="5" ViewCount="164" Body="&lt;p&gt;Looking around on the internet you can still find a lot of aged aircraft such as the 727,737-200,a300/310, DC9/MD8X and DC-10 that are still being used as freighters or in &quot;poorer&quot; airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose a lot of pilots that were certified on these aircraft are getting older and retiring. Would it make sense for a younger guy to get certified for these airplanes rather than running for a newer aircraft certifications where the competition would be harsher in order to pursue a career?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that these aircraft will still have service time left as converted freighters thus extending the retirement dates further on in time.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2014-03-31T08:26:08.200" LastActivityDate="2014-03-31T15:45:05.690" Title="Aged aircraft type ratings" Tags="&lt;aircraft-certification&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2014-03-31T17:04:38.283" ContentLicense="CC BY-SA 3.0" />
  <row Id="2911" PostTypeId="2" ParentId="2899" CreationDate="2014-03-31T06:01:28.997" Score="1" Body="&lt;p&gt;As has been described by others, a typical airplane headset will have two plugs, one for the microphone and one for the audio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no regulation requiring use of a headset or a minimum level of sound protection.  For airplane pilots, the universal use of headsets is a relatively new thing.  In the 1980s and earlier, it was common for small airplanes to have a hand-held microphone that could be used CB-style, and a speaker mounted somewhere in the cabin.  Most airplanes still have the (rarely used) speaker, but the hand-held microphones are becoming rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interior cabin noise can be pretty loud.  Without a headset, the noise level is not quite rock-concert loud, but it's definitely loud - about like the inside of a factory.  With an ANR headset, it's comparable to riding in a car at freeway speeds.  With a passive headset, it's in between, but closer to the quiet end than the loud end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several advantages of an ANR headset as well as a few disadvantages.  First, the maximum total noise reduction is greater.  Second, the noise reduction is weighted more heavily toward the lower frequencies.  It's possible to hear other sounds in the cabin more easily because the droning propeller noise is more strongly reduced.  Finally, an ANR headset is lighter and more comfortable because it does not need as much insulation and clamping pressure to block out the noise.  There are also some drawbacks.  ANR headsets are more expensive.  They do require batteries and these can die.  (Power supplied from the airplane is a possibility, but most airplanes don't have the capability).  A dead battery doesn't stop the headset from working, but the ANR advantages will be lost, and an ANR headset with a dead battery has less noise reduction than a passive headset.  Finally, sometimes ANR headsets will pick up interference, which might be electrical or the result of a physical factor, such as a vent blowing on them in exactly the wrong way, which can confuse the ANR and make some unpleasant noises for the wearer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nearly all small airplanes have connections for at least two headsets.  Most of them have a connection for every seat.  There is typically an intercom in the aircraft that allows all the passengers and pilot to talk to each other and hear ATC.  The pilot has a push-to-talk button on his control yoke that will enable transmitting on the aircraft's radio; anything spoken on the intercom is typically not transmitted.  Most intercoms have a volume control and an &quot;isolate&quot; feature that isolates the pilot and radios from the passengers, so the pilot is not distracted by them.  This is not a feature of the headsets, but of the electronics in the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While all aviation headsets serve the same basic functions, the more advanced ones have other features as well.  Common features include Bluetooth to connect to a cell phone or music player, volume control which may include left/right balance or treble/bass control, an aux input jack for connecting to a wired audio source or cell phone, and an auto-mute feature that will disable the music source when radio communication is being received.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can take a look at an ANR headset owner's manual here: &lt;br/&gt;&#xA;&lt;a href=&quot;http://www.lightspeedaviation.com/content/lightspeedaviation/file/ZuluUG_B3.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.lightspeedaviation.com/content/lightspeedaviation/file/ZuluUG_B3.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt; to clarify some of the questions asked.&#xA;Most older planes have an audio panel installed, whether it was done when they were new or more recently as a refit.  Some still have the handheld mic but others have removed it since it isn't really needed.  If you were for some reason flying a plane that had no headset connection, you wouldn't be able to wear any hearing protection, as then you couldn't hear the radio or passengers.  Gliders, of course, are quiet, so with them it doesn't matter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lifetime of ANR batteries varies but I usually get about 20 flight hours on a set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an ANR headset picks up interference it is just an annoyance.  It's like having an insect buzzing in your ear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers don't need push-to-talk to talk to the pilot or each other.  The push-to-talk is only to transmit on the radio.  Back seat passengers don't usually have a radio transmit button and some planes only have one for the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cell phones are prohibited in flight, but they can be used on the ground.  Other than calling someone to come pick you up from the airport, you often have to call ATC and notify them that you've landed.  If you're departing IFR from a non-towered airport, you'll also need to call ATC before you depart.  If you don't have a phone connection, you have to do all this with the engine off (otherwise the noise is too loud).&lt;/p&gt;&#xA;" OwnerUserId="1027" LastEditorUserId="1027" LastEditDate="2014-03-31T18:57:11.847" LastActivityDate="2014-03-31T18:57:11.847" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2912" PostTypeId="2" ParentId="2903" CreationDate="2014-03-31T07:12:12.673" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;But if I’m right that you wouldn’t stall straight away&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You &lt;strong&gt;will&lt;/strong&gt; stall &lt;strong&gt;right away&lt;/strong&gt;. You won't &lt;em&gt;pitch down&lt;/em&gt; immediately though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Immediately when you exceed 2.67G&lt;sup&gt;1&lt;/sup&gt;, the aircraft will start to buffet and kick back somewhat as pulling more on the yoke no longer causes increase in lift and the pitch up rate and acceleration will stop increasing. But the pitch will not stop increasing. The wings are still generating &lt;em&gt;some&lt;/em&gt; lift, just less than before stall. So you'll continue climbing until you run out of kinetic energy (which you will faster than usual because drag is increased in stall) and decelerate below the speed at which the stalled wings can't produce enough lift to balance the weight. At that point your speed will still be higher than the 60 knots, because at 60 knots the wings can balance the weight when not stalled, but in this case they are stalled already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;Taking 100 kts cruise and 60 kts &lt;em&gt;v&lt;sub&gt;s&lt;/sub&gt;&lt;/em&gt;. Internet search gives me just 44 knots for &lt;em&gt;v&lt;sub&gt;s&lt;/sub&gt;&lt;/em&gt; and that would mean 5.17G for stall at 100 knots while the certified limit is 5G, so you shouldn't be doing it at 100 knots, only up to 98.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="22726" LastEditDate="2019-03-30T04:01:54.233" LastActivityDate="2019-03-30T04:01:54.233" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2913" PostTypeId="2" ParentId="2907" CreationDate="2014-03-31T07:40:32.237" Score="19" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The airline could have radioed the pilot and asked what the trouble was.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The airline doesn't generally have a direct line of contact with their aircraft. That's the job of air traffic control. It might be possible for the airline to ring up ATC and see whether they can contact the aircraft, but if ACARS is turned off then the only viable option is HF radio which doesn't always work. Some aircraft have a satellite phone in the cockpit, no indication whether MH370 did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, it was the middle of the night. Might be tricky to get somebody at ATC to answer the phone.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the pilots did not respond, some jets could have been scrambled&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;By whom? Who is paying for that? If jets were scrambled every time an aircraft couldn't be reached over the ocean, there would be a &lt;em&gt;lot&lt;/em&gt; of false alarms.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;to checkout what is going on.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, you've got jets in the air, now where's the aircraft? Remember, it was nighttime and the aircraft wasn't on radar anyway. If they had turned off the lights, there would be no possible way to find the plane. By the time the jets get to where the flight was last estimated to be, they could have gone in any direction.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The scrambled jets could have followed the airliner for hours&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What's the range of your jets? Remember they would probably like to get back home too, so cut that in half. Where are they going? Whose airspace? If these are military jets, who clears them to fly into another country's airspace? Would Indonesia mind being overflown by Malaysian fighter jets on short notice in the middle of the night?&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-03-31T07:40:32.237" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2914" PostTypeId="2" ParentId="2674" CreationDate="2014-03-31T08:21:53.793" Score="16" Body="&lt;p&gt;Notice the retractable landing gear? With a tail-wheel design, the main gear work best at or ahead of the center of gravity. The Staggerwing has a neat and efficient retractable main gear, that folds onto the lower wing. But the lower wing has to be farther forward than usual for this to work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two wings on a biplane interfere with each other, but the biplane structure is very strong and stiff for its weight. So the Staggerwing's design gives up some wing efficiency for strength and light weight. Then it gives-up a little more for the reverse stagger that puts the downwash of the lower wing right under what should be the high pressure under the upper wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the design gets good speed from the retractable gear reducing drag. And both wings, upper and lower, join the fuselage at 90 degrees, with no struts or other sources of drag. Aerodynamically, a very clean design. the Beech Bonanza looked more modern, but the Staggerwing had the same cruising speed, 176 knots, 202 mph. It also had a 450 hp P&amp;amp;W Wasp Junior, while the Bonanza got along with a 300 hp Continental.&lt;/p&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="1897" LastEditDate="2014-03-31T12:21:46.287" LastActivityDate="2014-03-31T12:21:46.287" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2915" PostTypeId="2" ParentId="2903" CreationDate="2014-03-31T08:59:48.390" Score="2" Body="&lt;p&gt;You wouldn't necessarily stall if you applied abrupt elevator at, say, 100kts due to there being enough inertia to ensure that the airflow relative to the chord line (AoA) did not, infact, exceed the critical angle. &lt;/p&gt;&#xA;" OwnerUserId="1933" LastActivityDate="2014-03-31T08:59:48.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2917" PostTypeId="1" AcceptedAnswerId="2944" CreationDate="2014-03-31T12:23:29.447" Score="23" ViewCount="19449" Body="&lt;p&gt;When I'm reading about aviation, it's very common to see references to &lt;em&gt;Class B&lt;/em&gt; or &lt;em&gt;Class C&lt;/em&gt; airspace and airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the different classes and what are the differences between them?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="69" LastEditDate="2014-03-31T22:14:22.427" LastActivityDate="2015-07-23T15:19:38.017" Title="What is the difference between the airspace's classes (for non-pilots)?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;airspace&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2918" PostTypeId="2" ParentId="2917" CreationDate="2014-03-31T13:11:27.317" Score="21" Body="&lt;p&gt;The short version, for non-aviation people is as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class A:&lt;/strong&gt; All Airspace above 18,000 ft. Anybody flying here must receive a clearance from, be talking to, and be controlled by ATC.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class B:&lt;/strong&gt; Airspace within approximately 30 miles and 10,000 feet of the ground around the busiest airports in the US. Again, anybody flying here must receive a clearance from, be taking to, and be controlled by ATC.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class C:&lt;/strong&gt; Airspace within approximately 10 miles and 4,000 feet of airports that are less busy than Class B airports. The equipment requirements are less restrictive to fly in this airspace and pilots must be talking to ATC.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class D:&lt;/strong&gt; The airspace around the least busy airports that still require an ATC control tower. It is approximately 4 miles and 2,500 feet of airspace and they usually don't have radar so just coordinate with airplanes over the radio and by sighting them visually. Pilots must also talk to ATC before entering their airspace. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class E:&lt;/strong&gt; Airspace that does not require aircraft to talk to or be under the control of ATC unless the weather is worse than certain specified criteria.  Aircraft avoid each other by looking out the window, and while this is true in the other airspace above, it is particularly important here (and in Class G) since many aircraft don't talk to ATC. There is an exception for airports in Class E that have a control tower; pilots landing at these airports must contact the tower before entering the airport's airspace.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class F:&lt;/strong&gt; &lt;em&gt;Not used in the United States&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class G:&lt;/strong&gt; Uncontrolled airspace that aircraft do not have to talk to ATC at all, except that are some airports in Class G that have a control tower; pilots landing at these airports must contact the tower before entering their airspace.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="3504" LastEditDate="2015-01-02T21:05:45.467" LastActivityDate="2015-01-02T21:05:45.467" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2919" PostTypeId="2" ParentId="2907" CreationDate="2014-03-31T13:13:40.300" Score="4" Body="&lt;p&gt;The question presumes capabilities that don't exist (the ACARS satellite link doesn't &quot;know&quot; about the radar transponder), presumes the transponder was intentionally turned off (likely, but very speculative, we have no evidence), and presumes the airline monitors planes in flight (they do not), while ignoring the fact that Malaysian military radar operators had the transponder-less blip on their display(s), had radios, and were part of the military that would have sent fighters to investigate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because their range is finite and limited, air traffic radar will &quot;lose&quot; transponder signals when a plane flys out of view. Signals stopping is a constant occurrence. If I follow the timeline correctly, the copilot spoke to air traffic control after the transponder signal stopped. Air teaffic control are supposed to monitor the planes they are watching. Why didn't they ask the copilot what was up? When the transponder signal stopped, was the plane at a distance and altitude where  disappearing would be expected. ?&lt;/p&gt;&#xA;" OwnerUserId="1897" LastActivityDate="2014-03-31T13:13:40.300" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2920" PostTypeId="1" AcceptedAnswerId="2931" CreationDate="2014-03-31T14:44:40.143" Score="22" ViewCount="48676" Body="&lt;p&gt;Back in the early days of aviation radial engines were very popular, it seemed like all of the big planes of the 20s, 30s and early 40s used them.  But some time during WWII (or so it seems to me) aircraft manufacturers switched from radial engines over to inline engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was there a switch?  Why do modern manufacturers rarely, if ever, use radial engines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example of a Radial Engine for those who are unfamiliar:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/H9yKP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-03-19T14:58:59.713" LastActivityDate="2021-01-05T04:43:46.853" Title="Why are Inline Engines more commonly used than Radial Engines?" Tags="&lt;aircraft-design&gt;&lt;piston-engine&gt;" AnswerCount="5" CommentCount="12" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2921" PostTypeId="2" ParentId="2920" CreationDate="2014-03-31T14:57:11.473" Score="6" Body="&lt;p&gt;Radial engines are better from the durability/mechanics point of view: having radially distributed pistons distributes the loads better and the shaft will be stressed equally from all directions.&#xA;For resonance reasons you will (almost) always have an odd number of pistons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Times have changed and manifacturing techniques have improved*. The benefits of the radial design justify no more the additional complexity and design effort required**, but even then some are still produced today. Also, in some cases engines are simply car engines re-adapted for an aircraft, cutting sensibly on development costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/609/ratchet-freak&quot;&gt;Ratchet&lt;/a&gt; mentions, you have also the limited space for the pistons radially arranged, something that in the linear arrangement is limited only by the length available (and you could always switch to an H arrangement to double the number of pistons). Even if some multi-row radials exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On &lt;a href=&quot;http://en.wikipedia.org/wiki/Radial_engine#Radial_versus_inline_debate&quot; rel=&quot;nofollow noreferrer&quot;&gt;wiki&lt;/a&gt; they also raise some interesting points concerning mostly the cooling system, but also concerning placement of the engine and pilot field of view.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;*: mostly metallurgy (better materials) and construction techniques (less imperfections in the components). Also, a better understanding of the science behind combustion has led to more efficient designs of the combustion chambers that, together with the fuel, has increased the overall efficiency of the engines.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;**: on a radial engine you have the pistons all around (duh) and thus you need to have a distribution line that reaches all sides of the engine (one side only for a standard inline) and an injection system , especially for the bottom pistons, that does not suffer from being &quot;upside-down&quot; for all the time. Something that the inline approach does not (normally) need to take care of.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-03-31T20:22:27.067" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2922" PostTypeId="2" ParentId="2920" CreationDate="2014-03-31T15:39:20.917" Score="11" Body="&lt;p&gt;Radials tend to have a great power to weight ratio, but they are still heavy and complex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another big issue is their surface area. Compare a 300HP radial to a 300HP  opposed 6-cylinder and you'll see that the radial probably has 9 cylinders and a big round crank case that must sit upright, facing into the air stream. That causes a lot of drag. The opposed engine, however, can be placed inside a small aerodynamic cowling with openings only for cooling air (or none, if you water cool it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think what it all comes down to, however, is that radials are great at producing loads of horsepower and torque. You can stack radials up to something like 50 aircraft-engine-sized cylinders before the friction causes diminishing returns. But what aircraft on the market today needs 5000hp and a two-ton engine? Radials that produce lower HP can be replaced by significantly smaller opposed engines that work just as well or better, and radials that produce large amounts of HP can be replaced with turbine engines that vastly outperform them on the higher end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only real use for a new radial engine today is to hear the sweet music they produce.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-03-31T15:39:20.917" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2923" PostTypeId="2" ParentId="2910" CreationDate="2014-03-31T15:45:05.690" Score="10" Body="&lt;p&gt;It doesn't really make sense to &quot;go and get&quot; a type rating for any large aircraft. A type rating on a 727 would be very expensive for most people, when the airline that needs pilots will likely train you when you're hired. If the bulk of people that have the rating are gone, and the airline needs pilots, it will either have to be very patient when searching for pilots, or it will train new pilots.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-03-31T15:45:05.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2924" PostTypeId="1" AcceptedAnswerId="2927" CreationDate="2014-03-31T16:36:08.290" Score="6" ViewCount="1859" Body="&lt;p&gt;This question is somewhat related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1314/ive-been-denied-vfr-clearance-through-c-airspace-what-should-i-do&quot;&gt;this other one&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I listened to &lt;a href=&quot;http://www.youtube.com/watch?v=oHNvXPbZ7WI&quot; rel=&quot;nofollow noreferrer&quot;&gt;this exchange between a helicopter and Newark&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The helicopter wants to land at Newark. The controller tells the helicopter to remain clear of the Class B. I'm aware that the controllers must give clearance to operate in certain &lt;a href=&quot;https://aviation.stackexchange.com/questions/2917/what-is-the-difference-between-the-airspaces-classes&quot;&gt;classes of airspace&lt;/a&gt;, and the helicopter wasn't granted clearance to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was the helicopter denied (as far as can be deduced)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What should the pilot have done differently, either to get clearance to land at Newark or to anticipate not being able to?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-02T20:06:39.090" Title="Why was this helicopter denied entry to Class B airspace?" Tags="&lt;air-traffic-control&gt;&lt;class-b-airspace&gt;&lt;clearance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2926" PostTypeId="2" ParentId="2903" CreationDate="2014-03-31T17:04:35.280" Score="7" Body="&lt;p&gt;Imagine you throw an airplane with the bottoms of the wings facing forward at 500 knots. The aircraft is going very fast, but rest assured it is stalled. It could recover very, very easily because it has so much kinetic energy and there as a huge amount of airflow, but it is not producing lift the way itshould.&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2014-03-31T17:04:35.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2927" PostTypeId="2" ParentId="2924" CreationDate="2014-03-31T17:46:00.357" Score="19" Body="&lt;p&gt;According to the post at LiveATC, &lt;a href=&quot;http://www.liveatc.net/forums/atcaviation-audio-clips/sikorsky-pilot-can%27t-take-%27no%27-for-an-answer-during-ewr-shutdown/&quot;&gt;Newark was closed&lt;/a&gt;, apparently due to &lt;a href=&quot;http://www.nycaviation.com/2012/07/newark-airport-control-tower-evacuated-due-smoke/&quot;&gt;smoke in the tower&lt;/a&gt;. With the airport closed, nobody could be granted clearance to take off or land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of declaring an emergency, there's nothing the pilot(s) could have done to get clearance at Newark other than just waiting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an emergency situation like smoke in the tower, there wouldn't be anything published beforehand for the pilots to look up, but otherwise, pilots look at NOTAMS during their flight planning for planned closures or outages. Even in good weather, proper flight planning would also involve an alternate airport, anticipating the possibility that the intended airport might be closed for an emergency like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skyvector.com/?ll=40.617444444,-74.244583333&amp;amp;chart=119&amp;amp;zoom=3&quot;&gt;Eight miles south of Newark&lt;/a&gt; is &lt;a href=&quot;http://www.lindenairportnj.com/&quot;&gt;Linden Airport&lt;/a&gt;, a small uncontrolled field just outside the Class B surface area. If I had passengers in my ship who were trying to fly out of Newark, I would have radioed operations and asked them to send a limo to Linden to pick up my passengers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;[There is one part of the recording that says &quot;[inaudible]&quot;. The pilot is announcing his position at the Statue of Liberty, a reporting point for copters landing EWR.]&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="3504" LastEditDate="2015-01-01T22:04:46.667" LastActivityDate="2015-01-01T22:04:46.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2928" PostTypeId="1" AcceptedAnswerId="2929" CreationDate="2014-03-31T18:53:54.303" Score="7" ViewCount="1815" Body="&lt;p&gt;In the movie &lt;em&gt;Cash McCall&lt;/em&gt;, the main character, McCall, owns an aircraft that looks remarkably similar to a B-25 or B-26, but is painted yellow and has no turrets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have these aircraft been converted for private business use or were there business aircraft based on the design of WWII bombers?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-04-01T00:03:09.630" LastActivityDate="2019-10-03T17:47:59.067" Title="Have B-25's and B-26's been converted for private business use?" Tags="&lt;bomber&gt;&lt;aircraft-identification&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2929" PostTypeId="2" ParentId="2928" CreationDate="2014-03-31T19:07:45.320" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.imdb.com/title/tt0052680/trivia&quot;&gt;IMDB&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;McCall's plane is a demilitarized Douglas A-26 Invader, a type used in WWII. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the film was made in 1960, I imagine there were plenty of them around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The A-26 was known a the B-26 from 1948 to 1965, &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_A-26_Invader&quot;&gt;according to Wikipedia&lt;/a&gt;. The B-25 is easily distinguished because it has the twin tail.)&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-03-31T19:07:45.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2930" PostTypeId="1" AcceptedAnswerId="2932" CreationDate="2014-03-31T20:32:09.683" Score="3" ViewCount="518" Body="&lt;p&gt;Would it be technically feasible to install the &lt;a href=&quot;http://www.empa.ch/plugin/template/empa/%2a/107170/---/l=1&quot; rel=&quot;nofollow&quot;&gt;Pneumagic inflatable wing&lt;/a&gt; on the &lt;a href=&quot;http://www.silentfamily.de/index.php?id=12&quot; rel=&quot;nofollow&quot;&gt;Silent glider&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="1953" LastEditorUserId="1696" LastEditDate="2015-02-17T22:53:18.863" LastActivityDate="2015-02-17T22:53:18.863" Title="Could an inflatable wing be installed on a Silent glider aircraft?" Tags="&lt;wing&gt;&lt;glider&gt;&lt;fixed-wing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2931" PostTypeId="2" ParentId="2920" CreationDate="2014-03-31T20:36:13.493" Score="24" Body="&lt;p&gt;&lt;strong&gt;The big advantage of radials at the beginning was their large frontal area&lt;/strong&gt;, &lt;strong&gt;which meant they could be air cooled&lt;/strong&gt;. An inline air cooled engine can run pretty hot on the rear cylinder. The bigger the engine, the more of an issue cooling becomes. There are some huge air cooled radials, in sizes that would be unthinkable for an air cooled inline engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As technology advanced, more complex water cooled engines became more popular&lt;/strong&gt;. However &lt;strong&gt;air cooling was still a big advantage in military planes&lt;/strong&gt;, due to the absence of a delicate cooling system that could be damaged, enabling radials to persist in this arena. Of course these days no-one would dream of putting a piston engine in a fighter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowadays liquid cooling is almost universal for piston engines in general applications, with small aircraft being one of the few areas where air cooling has managed to hold out to some extent (see below.) In the absence of a military application that prefers air cooling, &lt;strong&gt;the large frontal area has become the radial engine's downfall&lt;/strong&gt;, due to the large aerodynamic drag it produces. The other problem is that &lt;strong&gt;the valve gear is quite complicated, which means overhead camshafts and multiple inlet/exhaust valves per cylinder are impractical.&lt;/strong&gt; This makes efficiency vs power to weight ratio a big issue as follows: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an engine to have good power to weight ratio it must run at high RPM. To run at high RPM it must breathe effectively. To do this with just two valves they have to open wide. To stop them colliding with the piston, the compression ratio must be low, which limits efficiency. Hence most modern engines have more than two valves per cylinder to get around this problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Further reading&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-2800&quot;&gt;Pratt &amp;amp; Whitney R-2800&lt;/a&gt;: 46L displacement, over 2000hp from an air cooled engine, by no means the biggest! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Radial_engine&quot;&gt;Excellent animation of the valve gear&lt;/a&gt;, which also tends to illustrate the difficulty of putting more than 2 valves on a cylinder. Also, lots of history (obviously.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In World War II both Double Wasps (46L air cooled radial) and Merlins (27L water cooled V, licensed from Rolls Royce in Britain and built locally by Packard) were used by the American military. I once read a very good authentic World War II discussion about the tactics of when to use air cooled radial fighters and when to use water cooled ones. Unfortunately I can't find it. &lt;a href=&quot;http://www.ww2aircraft.net/forum/aviation/radial-vs-liquid-cooled-engines-33738.html&quot;&gt;Here's one of the many discussions on the subject.&lt;/a&gt; Note that the Merlin had overhead camshafts and 4 valves per cylinder, like modern engines, whereas the Double Wasp obviously did not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Modern air cooled engines&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am more of an engine guy than a plane guy, but I've just been looking at modern air cooled aviation engines. They are only available in much smaller sizes than typical WWII fighter engines. Typically they have 4-6 cylinders, too few for a radial, but enough to cause cooling problems on the rear cylinder in an inline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The compromise is a flat (boxer) engine with 2 or 3 cylinders on each side. This also overcomes two other problems with radials: upper cylinders obstructing pilot view and oil collecting in the lower cylinder when stopped. You also have at least one of these problems with an inline, depending if you mount it upright or inverted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small aero engines can be either water cooled or air cooled. The designer has to ask: given the issue of reliability in aviation, does the weekend pilot really want an engine as complicated as the one in his car, with water cooling, cambelts and engine management, all of which could go wrong?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air cooled engines I've seen (Lycoming) do only have two valves per cylinder, all driven from a common camshaft. (A simpler choice than the cam ring on a radial) I haven't seen an air cooled flat engine with overhead cams and multiple valves per cylinder, but it would be easier achieve than doing the same thing on a radial.&lt;/p&gt;&#xA;" OwnerUserId="1952" LastEditorUserId="1696" LastEditDate="2015-05-04T15:06:40.543" LastActivityDate="2015-05-04T15:06:40.543" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2932" PostTypeId="2" ParentId="2930" CreationDate="2014-03-31T22:04:03.333" Score="2" Body="&lt;p&gt;Here are some of my thoughts. I'm not fully convinced about the tradeoffs though, which would require a little more work to figure out if it was beneficial:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The wing appears a lot thicker in the article than in the silent glider, adding more drag than the solid wing which it currently uses. To get it as thin would be challenge, since the article suggests that the benefit of adding pressure is marginal for the same wing, so you could only make it thicker. In an convential design, the fabric can be a lot thinner than here were it's got to hold a lot pressure. I'm sure you have to add metal wires to maintain the shape under load, adding a weight penalty.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Using a pure air-based system, I'm also somewhat unconvinced about the 'responsiveness' at the controls, since You'd only be transferring the loads at a single point into the (flexible) structure, rather than across an area as in the article example. An analogy of this is to think of trying to apple a torque force to the center of a pool noodle in water, and to observe the ends relative to the center. You might end up having to make a rather extensive wing root structure to make this work. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The benefit would be portability, but since the silent glider has an engine, this would probably not be of a huge concern, since you could get it where you wanted it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My verdict: It could probably be done, but I'm doubtful about the performance benefits. Then again, I'm only a first year aerospace engineering student, so you're welcome to come with thoughts and any criticism :)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-03-31T22:54:56.497" LastActivityDate="2014-03-31T22:54:56.497" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="2933" PostTypeId="1" AcceptedAnswerId="2943" CreationDate="2014-03-31T22:23:05.453" Score="13" ViewCount="4826" Body="&lt;p&gt;My brother and I are big into paint balling and aviation, and we've often wondered if it would be legal/possible to use an aircraft in a large scale paintball match?  Mainly to drop paintballs, or perhaps even bags of paint, onto participants to simulate air support.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few questions then, to cover this fully:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it even legal to begin with? &lt;/li&gt;&#xA;&lt;li&gt;Assuming it is legal, what is the&#xA;recommended way to do this?  Plane size? Configuration considerations?&lt;/li&gt;&#xA;&lt;li&gt;Lastly, is it legal to shoot back at the&#xA;plane?  Or is that just wildly unsafe?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I know, it's kind of a broader question, but I was hoping to get the entire answer in one place for ease of access to the answer.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-03-31T22:57:59.470" LastActivityDate="2014-04-01T21:38:53.153" Title="Is it legal to drop/shoot paintballs from an airplane?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2934" PostTypeId="2" ParentId="2933" CreationDate="2014-03-31T22:26:58.590" Score="7" Body="&lt;p&gt;For the FAA:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§ 91.15 Dropping objects.&lt;/p&gt;&#xA;&lt;p&gt;No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is legal to drop objects from an aircraft as long as no hazard is created. It's open to interpretation, but I would suggest that deliberately dropping bags of paint onto persons on the ground would be a hazard.&lt;/p&gt;&#xA;&lt;p&gt;Also, having dropped objects (pumpkins) from an aircraft attempting to hit a target, I can tell you that it's really hard. You will most likely miss, probably by a surprising distance. If you do try this, make sure you have a lot of room. Also keep in mind your required altitude minimums, as you must be able to land safely if your engine fails at any time.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-03-31T22:54:06.367" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2935" PostTypeId="2" ParentId="2873" CreationDate="2014-03-31T23:17:10.760" Score="16" Body="&lt;p&gt;User interface design is &lt;strong&gt;complex&lt;/strong&gt;. Incredibly complex. In a previous job, my company competed on the consumer market against an established company with an aerospace background. That was visible: their consumer products looked as complex as these cockpits. Ours didn't, because the lead designer was exceptional (think Apple-level UI genius). We learned quite a bit from the competition, understanding how that interface was hindering instead of helping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did that mean our product was simpler, could do less? No, in fact not. The main reason was that our UI was task-oriented instead of function-oriented. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the Falcon pictures above, you see a bit of that change. The classic cockpit is function-oriented. For everything that needs a control, there is a dial. And with lots of functions, there are lots of dials.  Quite a few displays are duplicated because the equipment is duplicated.  To take Terry's example, if you have 8 fuel tanks, there would be 8 gauges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you often use those 8 fuel gauges together, rarely in isolation. For instance, the task &quot;check fuel remaining&quot; sums the results; the &quot;check weight distribution&quot; task focuses on the differences instead of the total. A task-oriented UI works better if it focuses on those tasks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An additional benefit is that in combination with glass cockpits, you can pull up a big User Interface for the task at hand, since the same space can be reused for other tasks at other times. The classical sets of buttons and switches has a static layout and must share the available space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a case for this task-oriented UI, consider AF447. The pilots faced information overload, couldn't identify the task they needed to perform (recover from stall), nor the data they needed for that. Yet &lt;strong&gt;any&lt;/strong&gt; pilot when quizzed could tell you how to recover from a stall, and the plane definitely knew it was in a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luckily there's hope. The use of checklists is well-established. They're closely tied to tasks. Not identical, some checklists bundle multiple tasks because they happen at the same phase of flight but not for the same reason. Still, the basic concept is that you execute a set of checks and actions which together achieve a single goal. That conceptual model, extended to all tasks should define the cockpit, not so much the physical hardware. &lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2014-03-31T23:17:10.760" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2936" PostTypeId="2" ParentId="2928" CreationDate="2014-03-31T23:42:49.000" Score="6" Body="&lt;p&gt;Yes. After World War 2, surplus aircraft were cheap, plentiful, and offered great performance compared to pre-war designs, and many were converted to use as executive transports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-26/B-26 was no exception, being the basis for the &lt;a href=&quot;http://en.m.wikipedia.org/wiki/On_Mark_Marksman&quot;&gt;On Mark Marksman&lt;/a&gt; series. Some of the On Mark conversions involved pretty serious modifications like a new wing spar carrythrough and a new (and much uglier) cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-25, to my knowledge, had no comparable program carried out, but many became water bombers for use in fighting forest fires. There were undoubtedly some executive conversions made as well!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other types like the Lockheed Hudson/Ventura/Lodestar transports and patrol aircraft were also popular conversion choices. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-03-31T23:49:41.993" LastActivityDate="2014-03-31T23:49:41.993" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2937" PostTypeId="1" AcceptedAnswerId="2942" CreationDate="2014-04-01T00:02:37.097" Score="22" ViewCount="3152" Body="&lt;p&gt;&lt;em&gt;Janes aircraft recognition guide&lt;/em&gt; has a picture of this plane on the Lear 35 page. Does it have missiles on it or is this some special modification?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VuF6e.jpg&quot; alt=&quot;lear 35&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="8282" LastEditDate="2019-01-10T12:27:23.510" LastActivityDate="2019-01-10T12:27:23.510" Title="Does this Lear 35 have missiles on it?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="2938" PostTypeId="2" ParentId="2937" CreationDate="2014-04-01T00:27:15.203" Score="7" Body="&lt;p&gt;Apparently yes. Googling for the tail number turns up &lt;a href=&quot;http://www.airliners.net/search/photo.search?regsearch=N83FN&quot;&gt;more&lt;/a&gt; &lt;a href=&quot;http://www.myaviation.net/search/search.php?view=&amp;amp;regnr=N83FN&quot;&gt;pictures&lt;/a&gt;, as well as comments saying this particular plane is &quot;used to simulate missile attacks&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www2.l-3com.com/fi/Services.htm&quot;&gt;Here is the owning company&lt;/a&gt;, a defense contractor that among other things provides simulated air attacks for training exercises.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-04-01T00:27:15.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2939" PostTypeId="2" ParentId="2902" CreationDate="2014-04-01T02:15:25.067" Score="14" Body="&lt;p&gt;There are almost always opportunities to volunteer. However, joining CAP is a larger commitment than simply saying &quot;I'd like to volunteer to fly.&quot; You will need to attend regular meetings and perform non-pilot duties such has becoming an administrative officer or participating in recruiting and fund raising activities. For some squadrons, the budgets are tight, and the ratio of pilots to flights can be high. The complaint I heard from CAP members back in Idaho was that they hardly ever got to fly. This may be less true in other areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My suggestion to you would be to contact your local squadron. In your case, this will be a squadron within the &lt;a href=&quot;http://www.cawgcap.org/index.php/about-us/groups/group-2&quot; rel=&quot;noreferrer&quot;&gt;California Group 2 (San Francisco Bay)&lt;/a&gt;. They have senior squadrons located in &lt;a href=&quot;http://www.sq10.org/&quot; rel=&quot;noreferrer&quot;&gt;Palo Alto&lt;/a&gt;, &lt;a href=&quot;http://www.squadron188.org/home&quot; rel=&quot;noreferrer&quot;&gt;Oakland&lt;/a&gt;, &lt;a href=&quot;http://sq80.cawgcap.org/&quot; rel=&quot;noreferrer&quot;&gt;San Jose&lt;/a&gt; and elsewhere (senior squadrons are for adults 18+, whereas cadet squadrons are for children under 21. There are also composite squadrons for both seniors and cadets). Talk to them about their mission and what the experience would be like. If you're still interested, attend some meetings (you'll need to do this before they'll let you apply anyway). Then, after you have a good sense of what will be expected, if you believe in their mission, and you're willing to put in the time required, you should join.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all you're looking for is a way to build cheap (or free) flight hours as a private pilot, then that is probably the wrong reason to join, and you will likely be disappointed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;*Note from editor: The oddity in the ages of membership for the senior and the cadet groups should be explained. A person may join as a cadet in a squadron up to their eighteenth birthday, however, if they became a cadet before that, they may continue as such until their twenty-first birthday. Anyone joining the Civil Air Patrol after eighteen enters into the senior branch.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="12220" LastEditDate="2016-03-27T11:56:59.427" LastActivityDate="2016-03-27T11:56:59.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2940" PostTypeId="1" AcceptedAnswerId="2941" CreationDate="2014-04-01T03:09:30.187" Score="6" ViewCount="506" Body="&lt;p&gt;I'm visiting the US and will get my foreign licence verified, but this means that I won't have a US license or medical. I understand that it is a requirement to sign up for Duats and Duat?! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea or suggestion on how else to use it?&lt;/p&gt;&#xA;" OwnerUserId="1957" LastEditorUserId="69" LastEditDate="2014-04-01T19:24:39.373" LastActivityDate="2014-05-14T12:40:43.460" Title="How do visiting foreign pilots access Duats or Duat?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2941" PostTypeId="2" ParentId="2940" CreationDate="2014-04-01T03:35:17.147" Score="7" Body="&lt;p&gt;I've just arrived back home after being in the US for some months. I was required to have a FAA class 3 medical, because I did some flight training there, and luckily the one I've received is also is a student pilot certificate with the number on it you require to register for DUAT. Some of my colleges didn't have this number and so they were not able to register until getting there FAA pilot certificate. This will be send to your home adress, most probably when you are home again. In the US you'll only get a temporary certificate (peace of paper). The only number you'll find on it is your current license number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now what you can try: One of my colleges simply wrote an e-mail to duats helpdesk where he described his situation, giving all the information they require on their registration page with his foreign license number and attached a photography of his license and a proof that he'll be in the us for the next months. Less than 24 hours later he had a log-in. We had a student Visa, but if you don't have something like this, just try it without it, or take a photography of something else looking trustworthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck and enjoy your trip!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I was just looking for the e-mail address, but for any reason my browser refuses to load duats website. As far as I remember, you'll find it at the registration page. If someonewho can access the website likes to add the e-mail adress please feel free to do so, I would appreciate your help.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="343" LastEditDate="2014-04-01T03:42:01.483" LastActivityDate="2014-04-01T03:42:01.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2942" PostTypeId="2" ParentId="2937" CreationDate="2014-04-01T05:06:14.377" Score="30" Body="&lt;p&gt;No, it's not a missile, it's a towed target:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZuYuj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www2.l-3com.com/fi/towed_devices.htm&quot; rel=&quot;noreferrer&quot;&gt;Towed targets&lt;/a&gt; are used for &lt;a href=&quot;http://media.defenceindustrydaily.com/images/AIR_Learjet_L-3_with_EW_Stores_lg.jpg&quot; rel=&quot;noreferrer&quot;&gt;electronic warfare&lt;/a&gt; and gunnery &lt;a href=&quot;http://www.defenseindustrydaily.com/lease-and-learn-l-3s-ew-training-aircraft-05378/&quot; rel=&quot;noreferrer&quot;&gt;training&lt;/a&gt;. The can serve as a radar target or visual target during military exercises.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 'missile' is on a long cord and can be reeled from the aircraft. The pod that you see here is a &lt;a href=&quot;http://www.airaffairs.com.au/reeling_machine.html&quot; rel=&quot;noreferrer&quot;&gt;MTR-101 reeling system&lt;/a&gt; with the capability to drag the target up to 30,000 ft behind the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested in flying these kind of missions, it seems  L3 is looking for a new &lt;a href=&quot;http://www.linkedin.com/jobs2/view/12786575&quot; rel=&quot;noreferrer&quot;&gt;First Officer&lt;/a&gt; for their Learjets.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="3386" LastEditDate="2016-04-03T10:26:00.897" LastActivityDate="2016-04-03T10:26:00.897" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2943" PostTypeId="2" ParentId="2933" CreationDate="2014-04-01T05:45:15.183" Score="9" Body="&lt;p&gt;Greg covered this very well &lt;a href=&quot;https://aviation.stackexchange.com/a/2934/64&quot;&gt;in his answer&lt;/a&gt;.&lt;br&gt;&#xA;The &quot;miss by a surprising distance&quot; bit is especially important here in the context of FAR 91.15 -- you would have to have a &lt;strong&gt;&lt;em&gt;VERY&lt;/em&gt;&lt;/strong&gt; large-scale paintball match for this to be viable, and some specific rules of engagement for the aircraft (always firing &quot;into&quot; the arena area as you don't want to miss and send a paintball into someone's car or kitchen window as that would get some distinctly unfriendly attention from the FAA, and probably the local constabulary).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operationally, if we're doing this with an airplane high-wing aircraft would obviously be the order of the day (Cessna 152), with a pilot (whose sole job is to fly the airplane) and a gunner/bombardier (who is responsible for hitting targets on the ground). You &lt;em&gt;really&lt;/em&gt; don't want the pilot distracted by the game.&lt;br&gt;&#xA;Your weapons guy is going to have to be able to account for the aircraft's speed and altitude in targeting (which is pretty hard with an adjusted scope/bomb sight - doing it without one is going to be tough).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for shooting back at the plane, if we're talking about a &quot;regular&quot; airplane (something manned, like a Cessna 152) I would advise against allowing players to target the plane. At safe operating altitudes they're unlikely to hit the plane, but if they do aircraft skin is very thin &amp;amp; dent repair is very expensive: If someone is lucky enough to score a hit it could be a costly &quot;death&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, as a paintball player myself I will tell you that I find the idea of death from above when I can't shoot back at the aircraft to be rather unsporting!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I would suggest instead is to deploy &lt;a href=&quot;http://en.wikipedia.org/wiki/Quadcopter&quot; rel=&quot;nofollow noreferrer&quot;&gt;quadcopter drones&lt;/a&gt;. These can be had pretty cheaply and with some basic electronics skills they can be modified to carry/drop paint grenades (think Squadbusters) on your enemy.&lt;br&gt;&#xA;If you want to get &lt;em&gt;really fancy&lt;/em&gt; add a GoPro or some other remote camera to help with targeting, or add a paintball gun to the thing &lt;a href=&quot;http://gizmodo.com/5968058/an-awesome-guy-made-a-flying-drone-armed-with-a-paintball-gun/all&quot; rel=&quot;nofollow noreferrer&quot;&gt;like these folks did&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA's rules for &quot;unmanned aerial systems&quot; are still being written, but if you keep to the general rules for model aircraft (below 400 feet, and not charging anyone money for the drone's services) I think you'll be OK (when the final rules come out you'll have to review your drone for compliance).&lt;br&gt;&#xA;As a bonus if the drone isn't too large and you have an indoor arena with liberally-minded management you may even be able to use your drone during indoor games.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Kill rules for the drone and its operator are left as an exercise for the players.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-04-01T05:45:15.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2944" PostTypeId="2" ParentId="2917" CreationDate="2014-04-01T07:57:59.460" Score="23" Body="&lt;p&gt;Although Lnafziger's answer is correct, I'd like to elaborate on the &lt;em&gt;purpose&lt;/em&gt; of the airspace classes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class A:&lt;/strong&gt; This airspace is intended for high-speed, point to point travel.  That is why pilots flying in Class A must be instrument rated and in contact with air traffic control (ATC); aircraft above 18,000 feet are likely to travel quickly and may not have time to avoid each other visually.  This is the upper layer of the airspace system.*&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class B:&lt;/strong&gt; This airspace is intended for large airports with lots of jet traffic.  The large number and size of aircraft require space for ATC to get them efficiently in and out of the airports.  Approach control services are provided.  As a result, class B areas are physically large.  It is possible for small aircraft flying under visual flight rules to operate here with explict ATC permission, though permission to enter may be denied during periods of high traffic.  Small piston-powered aircraft land at Class B airports infrequently, typically due to high landing fees and fuel prices.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class C:&lt;/strong&gt; Smaller airports with a mix of piston-powered aircraft and jets.  Most Class C airports are home to flight schools and small aircraft hangars as well as scheduled service by airlines.  While still busy, Class C airports have less traffic than Class B, so ATC doesn't need as much space to keep them organized.  Like Class B, approach control services are provided.  Pilots are only required to establish two-way communication to enter the airspace.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class D:&lt;/strong&gt; The smallest airspace type for tower-controlled airports, traffic primarily consists of general aviation aircraft.  Often these airports handle cargo, business jets, charter service, maintenance or assembly facilities, etc. as well as private aircraft and flight schools.  They also host firefighting operations, airshows, or anything else that needs facilities but would interfere with normal traffic if put at a larger airport.  Although Class D airports are small, some are very busy; others handle only a few flights an hour.  Approach control services are only provided if the airport is near Class B or C airspace.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class E:&lt;/strong&gt; This is the lowest level of &quot;controlled airspace.&quot;  &quot;Controlled&quot; doesn't mean you have to talk to ATC, but that ATC services are available (within the capabilities of radar and radio equipment).  This is general-purpose airspace.  Aircraft flying under visual flight rules can fly more-or-less whatever they want (weather permitting), and instrument flight rules traffic operate under positive control by ATC.  There are regulations in this airspace, but they aren't onerous, and they're designed to accommodate the wide variety of aircraft and activities that are found here.  Some small airports have Class E airspace surrounding them at the ground.  Although Class E is a single class of airspace, there are tighter regulations above 10,000 feet, where there are no speed restrictions (other than the prohibition on supersonic flight over land), compared to at lower altitudes where speeds are limited to 250 knots.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class F:&lt;/strong&gt; See &lt;a href=&quot;https://aviation.stackexchange.com/questions/406/what-is-class-f-airspace-and-why-is-it-not-used-in-the-us&quot;&gt;What is Class F airspace, and why is it not used in the US?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class G:&lt;/strong&gt; This is found near the ground everywhere except controlled airspace around airports, and occasionally at higher altitudes in remote areas (Alaska or the Rockies, usually), but never above 14,500 feet.  Most untowered airports have Class G airspace surrounding them.  This is &quot;uncontrolled&quot; airspace, so there is no ATC service available at all.  Radio and radar work better the higher you go, so at low altitudes you just can't expect good results.  Class G serves as a notice that ATC services are unavailable, typically due to a lack of radar coverage.  In remote areas, the same problems occur at higher altitudes (radar won't see you if you go behind a mountain, and sometimes you're just too far) so Class G is found there as well.  Most of the time, the only reason anybody goes into Class G airspace is because they're taking off or landing at an uncontrolled airport, or transiting certain areas that lack radar coverage.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Other:&lt;/strong&gt; There are many kinds of special-use airspace, all of which serve as keep-out signs of varying levels from &quot;please be considerate&quot; up to &quot;will shoot on sight.&quot;  In the US, these don't really interact with airspace classification.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;p&gt;&#xA;* Technically, airspace above 60,000 feet is Class E, but nobody goes up there except scientific and spy/military flights.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="1027" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-17T23:38:12.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2945" PostTypeId="2" ParentId="2933" CreationDate="2014-04-01T08:12:57.127" Score="3" Body="&lt;p&gt;&lt;strong&gt;Is it even legal to begin with?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm going to say no. Yes, 91.15 does allow the dropping of objects:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But 91.13(a) says.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is also 91.119(a)-(c)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.119 Minimum safe altitudes: General.&#xA;  Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Over congested areas. Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For an aircraft to be at all involved in a paintball match, it will need to be doing low altitude maneuvers. This will violate one of the above laws. I'd say the most assured is 91.119(a). An engine failure in that situation would be very dangerous to the people on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I absolutely believe, based on my experience with the FAA investigators, they would not consider this legal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Assuming it is legal, what is the recommended way to do this? Plane size? Configuration considerations?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My very strong recommendation is that you never, ever do this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Lastly, is it legal to shoot back at the plane? Or is that just wildly unsafe?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://codes.lp.findlaw.com/uscode/18/I/2/32&quot; rel=&quot;nofollow&quot; title=&quot;18 U.S.C. § 32 : US Code - Section 32: Destruction of aircraft or aircraft facilities&quot;&gt;18 U.S.C. § 32 : US Code - Section 32: Destruction of aircraft or aircraft facilities&lt;/a&gt; says you can get 20 years for damaging an airplane. I'd also say it's wildly unsafe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I say this all as a pilot who has dropped his share of stuff from airplanes. Rubber chickens onto a toy house at an airport as part of a competition, toilet paper to tear up with my prop, pumpkins in the marsh and paper bags filled with flour. There is a time and a place for it, and a paintball match isn't it.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-04-01T08:12:57.127" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2946" PostTypeId="2" ParentId="2907" CreationDate="2014-04-01T10:48:13.433" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why is there no alarm when the transponder is turned off?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because airlines trust their pilots and have systems in place to ensure their pilots are trustworthy. It is probably right to concentrate on preventing untrustworthy persons entering the cockpit before worrying about real-time remote monitoring of the actions of untrustworthy persons in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The satellite kept getting pings, and apparently &quot;knew&quot; that the transponder was off.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is not correct. The ACARS system and the transponder are separate systems. The satellite in orbit &quot;knows&quot; nothing, it's just a relay. The satellite's base station receives the data and forwards it to customers whilst monitoring the satellite service/performance. As I understand it, the base station equipment is not expected to peek into their customer's data content and make judgements about it's meaning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACARS uses VHF over land and only uses satellite communications (SATCOM) when out of VHF range. So the satellite systems not receiving data is not unusual and should not trigger an alarm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Inmarsat satellite ground station could not inferred that ACARS had been turned off inappropriately. This is because it doesn't know if the aircraft has landed and systems turned off normally. The Inmarsat company probably don't know every time an aircraft deviates from schedule, e.g. to divert back at the airport to check a fault light. The Inmarsat base station also didn't know the location of the aircraft other than it was somewhere on that side of the planet. The hourly handshake is conducted using the broad regional beam, not one of the narrower beams.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is fortunate that Inmarsat keep logs and that the logging system chooses to keep certain data such as signal strength and frequency rather than discarding it. This enabled Inmarsat's engineers to analyse those logs days and weeks after the events. But this analysis is not routine and real-time (and it would probably be a very inappropritae solution to make it so). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Malaysian Airlines had not subscribed to the more continuous† data reporting systems available through ACARS (and Inmarsat). So the absence of ACARS or other transmission is even more unremarkable from Inmarsat's perspective at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the normal course of things it is not the job of Inmarsat to interpret the data being transmitted  to it's customers (the airline, plane maker, engine maker etc). It's job is to relay data to it's customers and those customers can then use that data as they need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since those customers had not subscribed for continuous† transmission, no-one could know what  was happening in the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the continuous† transmission was subscribed to, there is no guarantee that the state of the transponder would be part of that data, nor that there would be a monitoring system at the airline capable of issuing alerts for unusual settings of the transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACARS itself is just a reporting system. I believe the content of the data reported is selected by the airline.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Notes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;† By continuous I mean the sort of monitoring used for AF447. As I understand it, this isn't completely continuous, just more frequent reporting and as-needed throughout the flight to report certain events as they arise.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-04-01T10:48:13.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2947" PostTypeId="2" ParentId="1400" CreationDate="2014-04-01T12:08:36.283" Score="21" Body="&lt;p&gt;There is more to a T-tail than that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerodynamics:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The placement on top of the vertical gives it more leverage,&#xA;especially with a swept tail.&lt;/li&gt;&#xA;&lt;li&gt;Depending on wing location, it stays in undisturbed flow in a stall. Note: This is really depending on the details, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hamburger_Flugzeugbau_HFB-320_Hansa_Jet&quot; rel=&quot;noreferrer&quot;&gt;HFB-320&lt;/a&gt; had a forward swept wing and a T-tail, which made a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8022/what-is-a-deep-stall-and-how-can-pilots-recover-from-it/8027#8027&quot;&gt;deep stall&lt;/a&gt; possible (and in one case fatal).&lt;/li&gt;&#xA;&lt;li&gt;By designing the junction with the vertical well, the T-tail has less interference drag. It also helps to reduce wave drag, especially when using a well designed Küchemann body (the round, long, spiky thing on the tail junction of a Tu-154) by stretching the structure lengthwise.&lt;/li&gt;&#xA;&lt;li&gt;It can help to increase the effectiveness of the vertical tail by keeping the   air on both sides of it separated. At the other end, the fuselage does this already, so moving the horizontal tail up does not hurt so much there. As a consequence, the tail can be built lower.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Structure:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The mass of the horizontal tail on a long lever arm (= the vertical tail) means that the torsional eigenfrequency of the fuselage will go down. This might be a problem in case of flutter.&lt;/li&gt;&#xA;&lt;li&gt;As a consequence of the smaller vertical tail, a T-tail can be lighter. Note that the increased leverage means that the horizontal tail can be smaller as well. This reduces friction drag and is the main reason why most modern gliders have T-tails.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Control:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A T-tail produces a strong nose-down pitching moment in sideslip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it were not for the flutter and pitch-down, T-tails would be more widespread ...&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-07-25T20:35:41.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2949" PostTypeId="1" AcceptedAnswerId="2951" CreationDate="2014-04-01T15:12:39.153" Score="12" ViewCount="6435" Body="&lt;p&gt;ATC will sometimes give pilots the instruction to &lt;code&gt;maintain visual separation&lt;/code&gt; from nearby traffic.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a couple questions about this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is a related question &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight&quot;&gt;here&lt;/a&gt; about traffic separation.&lt;br&gt;&#xA;Is the required separation in this case different, and how can they judge this? (I would like a bit more detail for this specific case than was provided on the answer there)&lt;/li&gt;&#xA;&lt;li&gt;Normally pilots will follow their flight plan and ATC instructions. What actions should pilots take to maintain separation? I mean, obviously whatever is necessary, but is there any standard method? Should they anticipate an issue and ask ATC if they need to change course?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is mostly focused on IFR traffic, but how different would VFR be? The situation could be that ATC clears you for a certain maneuver, and other traffic interferes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is my understanding that for IFR traffic the controller would expect that there would be no conflict, but things don't always go as planned.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-09-14T21:41:46.770" Title="What are the pilot responsibilities for &quot;maintain visual separation&quot; clearances?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2950" PostTypeId="2" ParentId="2949" CreationDate="2014-04-01T15:25:25.377" Score="0" Body="&lt;p&gt;ATC will use radar to judge how far apart planes are, in absence of ATC (uncontrolled airspace) it is purely scanning the sky and paying attention this is called See and Avoid and is always in force even during IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot notices he is on a collision course with another plane he may do anything in his power to avoid said collision. For many planes there is &lt;a href=&quot;https://aviation.stackexchange.com/questions/1883/how-does-tcas-work&quot;&gt;TCAS&lt;/a&gt; an automated system to help pilots avoid collisions by issuing a climb or descend command to the pilot if collision is near. If such a command happened then the pilot MUST follow it to minimize chance of collision and notify ATC.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-04-01T15:25:25.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2951" PostTypeId="2" ParentId="2949" CreationDate="2014-04-01T15:50:07.703" Score="19" Body="&lt;p&gt;Visual separation is addressed specifically in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0505.html&quot;&gt;AIM&lt;/a&gt; (see below).  It &lt;em&gt;is an ATC instruction&lt;/em&gt; sometimes given when the pilot reports another aircraft in sight.   ATC is then able to instruct the pilot to &quot;maintain visual separation&quot; from the other aircraft, and it doesn't matter if they are IFR or VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then it becomes quite simple:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;strong&gt;Don't hit the other airplane!&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do whatever you have to do in order to avoid them.  (Usually this is nothing since you just get closer than ATC is allowed to let you otherwise.) &lt;/li&gt;&#xA;&lt;li&gt;If you are on a specific ATC clearance, then notify ATC immediately if you have to do something contrary to that clearance.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Keep the other aircraft in sight.&lt;/strong&gt; &#xA;&lt;ul&gt;&#xA;&lt;li&gt;Immediately report to ATC if you lose sight of them.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Avoid the wake turbulence of the other aircraft.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Standard radar separation no longer applies since the pilot has accepted separation responsibility from the one specific aircraft that the clearance applies to.  This allows ATC to let aircraft fly more efficient routes (not having to turn to avoid the other aircraft) and also lets more aircraft land in a given amount of time because they can be closer together on final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots have to use good judgement as to how close they get to the other aircraft, but it is done visually.  They can use any tools at their disposal to help (TCAS, asking ATC how far away they are, etc.) but it all comes down to &quot;that looks good enough for me&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Section 5. Pilot/Controller Roles and Responsibilities&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0505.html&quot;&gt;5-5-12. Visual Separation&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a. Pilot.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; Acceptance of instructions to follow another aircraft or to provide visual separation from it is an acknowledgment that the pilot&#xA;  will maneuver the aircraft as necessary to avoid the other aircraft or&#xA;  to maintain in‐trail separation. Pilots are responsible to maintain&#xA;  visual separation until flight paths (altitudes and/or courses)&#xA;  diverge.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2.&lt;/strong&gt; If instructed by ATC to follow another aircraft or to provide visual separation from it, promptly notify the controller if you lose&#xA;  sight of that aircraft, are unable to maintain continued visual&#xA;  contact with it, or cannot accept the responsibility for your own&#xA;  separation for any reason.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;3.&lt;/strong&gt; The pilot also accepts responsibility for wake turbulence separation under these conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b. Controller. Applies visual separation only:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; Within the terminal area when a controller has both aircraft in sight or by instructing a pilot who sees the other aircraft to&#xA;  maintain visual separation from it.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2.&lt;/strong&gt; Pilots are responsible to maintain visual separation until flight paths (altitudes and/or courses) diverge.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;3.&lt;/strong&gt; Within en route airspace when aircraft are on opposite courses and one pilot reports having seen the other aircraft and that the&#xA;  aircraft have passed each other.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More info is here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0404.html#aim0404.html.9&quot;&gt;&lt;strong&gt;4-4-14. Visual Separation&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Visual separation is a means employed by ATC to separate aircraft in terminal areas and en route airspace in the NAS. There are&#xA;  two methods employed to effect this separation:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; The tower controller sees the aircraft involved and issues instructions, as necessary, to ensure that the aircraft avoid each&#xA;  other.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2.&lt;/strong&gt; A pilot sees the other aircraft involved and upon instructions from the controller provides separation by maneuvering the aircraft to&#xA;  avoid it. When pilots accept responsibility to maintain visual&#xA;  separation, they must maintain constant visual surveillance and not&#xA;  pass the other aircraft until it is no longer a factor.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;   Traffic is no longer a factor when during approach phase the other aircraft is in the landing phase of flight or executes a&#xA;  missed approach; and during departure or en route, when the other&#xA;  aircraft turns away or is on a diverging course.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; A pilot's acceptance of instructions to follow another aircraft or provide visual separation from it is an acknowledgment that the&#xA;  pilot will maneuver the aircraft as necessary to avoid the other&#xA;  aircraft or to maintain in-trail separation. In operations conducted&#xA;  behind heavy jet aircraft, it is also an acknowledgment that the pilot&#xA;  accepts the responsibility for wake turbulence separation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;   When a pilot has been told to follow another aircraft or to provide visual separation from it, the pilot should promptly notify&#xA;  the controller if visual contact with the other aircraft is lost or&#xA;  cannot be maintained or if the pilot cannot accept the responsibility&#xA;  for the separation for any reason.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;c.&lt;/strong&gt; Scanning the sky for other aircraft is a key factor in collision avoidance. Pilots and copilots (or the right seat passenger)&#xA;  should continuously scan to cover all areas of the sky visible from&#xA;  the cockpit. Pilots must develop an effective scanning technique which&#xA;  maximizes one's visual capabilities. Spotting a potential collision&#xA;  threat increases directly as more time is spent looking outside the&#xA;  aircraft. One must use timesharing techniques to effectively scan the&#xA;  surrounding airspace while monitoring instruments as well.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;d.&lt;/strong&gt; Since the eye can focus only on a narrow viewing area, effective scanning is accomplished with a series of short, regularly&#xA;  spaced eye movements that bring successive areas of the sky into the&#xA;  central visual field. Each movement should not exceed ten degrees, and&#xA;  each area should be observed for at least one second to enable&#xA;  collision detection. Although many pilots seem to prefer the method of&#xA;  horizontal back-and-forth scanning every pilot should develop a&#xA;  scanning pattern that is not only comfortable but assures optimum&#xA;  effectiveness. Pilots should remember, however, that they have a&#xA;  regulatory responsibility (14 CFR Section 91.113(a)) to see and avoid&#xA;  other aircraft when weather conditions permit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For even more information, there is an &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0702.html#atc0702.html.1&quot;&gt;entire section&lt;/a&gt; of the Air Traffic Control job aid which the controllers use about visual separation.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-01T21:05:26.363" LastActivityDate="2014-04-01T21:05:26.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2952" PostTypeId="1" CreationDate="2014-04-01T17:29:33.167" Score="96" ViewCount="83765" Body="&lt;p&gt;It is quite a common phrase, usually without having anything to do with radar or aviation. But. Is there such a thing as 'flying &lt;em&gt;under&lt;/em&gt; the radar'? If so, why is this (and how low is that)?&lt;/p&gt;&#xA;" OwnerUserId="1379" LastEditorUserId="8000" LastEditDate="2015-12-17T18:34:49.667" LastActivityDate="2020-06-11T19:03:27.497" Title="Can someone actually &quot;fly under the radar&quot;?" Tags="&lt;radar&gt;" AnswerCount="11" CommentCount="7" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2953" PostTypeId="2" ParentId="2952" CreationDate="2014-04-01T17:38:08.000" Score="7" Body="&lt;p&gt;ATC radar is line of sight and doesn't follow the curvature of the earth. It does a bit but not enough to stay parallel to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radar is also blocked by terrain (read: mountains).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is one of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar#Limiting_factors&quot;&gt;limiting factors of radar&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-04-01T17:38:08.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2954" PostTypeId="2" ParentId="2952" CreationDate="2014-04-01T17:38:17.797" Score="88" Body="&lt;p&gt;In many cases, yes you can fly under the radar because typical civilian radar is line of sight, meaning that it has to have a straight unobstructed path to an object in order to &quot;see&quot; it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is because it works by sending a radar signal out and waiting for it to reflect off of something.  If it reflects off of another object, like the ground, a mountain, a building, a thunderstorm, etc. then it won't see what is behind it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the earth is round, flying &quot;under&quot; the radar is flying beneath the coverage area that the radar can &quot;see&quot; directly from where it is, and the height of radar coverage depends on the distance from the site as well as the terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example is here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://content.answcdn.com/main/content/img/McGrawHill/Aviation/f0524-01.gif&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AcYtR.gif&quot; alt=&quot;Radar Line of Sight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The top half shows how the curvature of the earth affects it and the bottom half shows how other objects can shadow radar (even though is is using aircraft radar, the same principle applies).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That being said, there are other types of radar and other ways of utilizing radar that minimize this problem and make it nearly impossible to fly under it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One common type in use is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tethered_Aerostat_Radar_System&quot;&gt;Tethered Aerostat Radar System&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.fas.org/nuke/guide/usa/airdef/tars-HTARS5.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RPBPim.jpg&quot; alt=&quot;Radar balloon&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is downward looking radar attached to a 25,000 ft. tether.  From 15,000 ft. it can detect aircraft and even vessels all of the way down to the surface of the ocean out to 200 miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another type is &lt;a href=&quot;http://en.wikipedia.org/wiki/Over-the-horizon_radar&quot;&gt;Over-The-Horizon Radar&lt;/a&gt; which can see further by reflecting radar off of the ionisphere like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://content.answcdn.com/main/content/img/McGrawHill/Aviation/f0475-02.gif&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3vkIf.gif&quot; alt=&quot;OTHR&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-06T14:56:11.237" LastActivityDate="2014-04-06T14:56:11.237" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2955" PostTypeId="2" ParentId="2952" CreationDate="2014-04-01T17:38:32.960" Score="27" Body="&lt;p&gt;Secondary Surveillance Radars work on 1030 MHz and 1090 MHz. Most primary radars work at higher frequencies. Signals at these frequencies do not follow the curvature of the earth very well. They work best in line of sight. Aircraft far away from the radar must be at high altitude to be above the horizon, otherwise they are &quot;under the radar&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flat terrain at 1 000ft, the horizon is about 33 nautical mile away. Aircraft further away will be shielded below the horizon. For 40 000ft, the horizon is about 220 nautical mile away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v3dnQ.png&quot; alt=&quot;L-Band signal horizon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;L-Band signal horizon&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to a slight refraction of the signal the practical range is somewhat further than the visual line of sight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the signal is also blocked by terrain; nearby hills and mountains obstruct views.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-12-15T20:53:30.227" LastActivityDate="2015-12-15T20:53:30.227" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2956" PostTypeId="2" ParentId="2952" CreationDate="2014-04-01T17:42:52.843" Score="71" Body="&lt;p&gt;It is certainly possible to fly &quot;under the radar.&quot; Military pilots practice a type of flying called &lt;a href=&quot;http://en.wikipedia.org/wiki/Nap-of-the-earth&quot; rel=&quot;noreferrer&quot;&gt;nap-of-the-earth&lt;/a&gt; for exactly this purpose. This tactic is primarily used by smaller fighters and attack aircraft, but larger planes like the B-1 are also capable of this. Here is why this tactic may be useful:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In civil aviation, mountains or other terrain can block radar signals. Going too low in a mountainous area will take you out of their radar coverage. For this reason, controllers have &lt;a href=&quot;http://www.skybrary.aero/index.php/Minimum_Vectoring_Altitude_%28MVA%29&quot; rel=&quot;noreferrer&quot;&gt;Minimum Vectoring Altitudes&lt;/a&gt;. These are based both on the radar coverage and terrain so that ATC can ensure aircraft will be at a safe altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a cross section of how radar coverage may look. Obstructions can block lower portions of the coverage as it radiates outward from the radar facility. The red indicates the normal radar used by ATC (the green is called &quot;over the horizon&quot; radar, generally used for military early warning radar).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xn6xz.png&quot; alt=&quot;Diagram showing radar view vs. horizon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even military radars have a limit of the lowest altitude at which they can track aircraft. This is because the radar signal will also reflect off of the ground and objects on the ground, causing interference. This is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_signal_characteristics#Clutter&quot; rel=&quot;noreferrer&quot;&gt;clutter&lt;/a&gt; and can be avoided by Doppler radars that detect velocity. The concept of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_horizon&quot; rel=&quot;noreferrer&quot;&gt;radar horizon&lt;/a&gt; determines the point at which clutter will no longer affect the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SA-6 air defense system can engage targets using radar &lt;a href=&quot;http://www.fas.org/man/dod-101/sys/missile/row/sa-6.htm&quot; rel=&quot;noreferrer&quot;&gt;down to 100m&lt;/a&gt;, and the SA-8 can engage &lt;a href=&quot;http://www.fas.org/man/dod-101/sys/missile/row/sa-8.htm&quot; rel=&quot;noreferrer&quot;&gt;down to 10m&lt;/a&gt;. These are both short range systems, though (less than 30km).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.newcastleairport.com/Media/pdf/radar-blanking-strategy-pdf.pdf&quot; rel=&quot;noreferrer&quot;&gt;This report&lt;/a&gt; has some references about areas on ATC radar that are difficult to cover because of obstacles such as wind farms. Because the radar doesn't distinguish altitude, controllers may not be able to distinguish an aircraft within these areas of interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a2DQH.png&quot; alt=&quot;Radar image with areas of interference labeled&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-12-16T22:19:37.057" LastActivityDate="2015-12-16T22:19:37.057" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2957" PostTypeId="2" ParentId="2940" CreationDate="2014-04-01T19:02:42.467" Score="6" Body="&lt;p&gt;Falk is correct; you can contact the service providers directly, explain your situation and they should be able to provision an account without a US pilot's license or medical certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DTC DUAT (duat.com) can be reached anytime at: 800-243-3828&lt;br /&gt;&#xA;CSC DUATS (duats.com) can be reached anytime at: 800-345-3828&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an alternative, may I recommend trying Lockheed Martin Flight Services' Pilot Portal at &lt;a href=&quot;https://www.lmfsweb.afss.com&quot;&gt;https://www.lmfsweb.afss.com&lt;/a&gt;.  They are the flight services contract provider for the FAA.  You can create an account by simply providing a valid email address.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It provides all of the same functionality as DUAT/DUATS, but Lockheed's briefing products are the exact same ones their telephone briefers use. Their website has a tool called &quot;NextGen Briefing&quot; that translates all of your briefing data into plain text, which makes reading your brief super fast and easy.  Of course, you can also read the coded text, if you're into that kind of thing (or you're training).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the website, you can also create a pilot profile that is linked to your mobile number so when you call 800-WX-BRIEF to file a flight plan, their computers will prefill your aircraft data for you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also file, ACTIVATE and CLOSE flight plans through the website.  Also, unlike DUAT(S), flight plans are immediately available to ATC/Flight Service when filed. &lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2014-04-01T19:02:42.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2958" PostTypeId="1" CreationDate="2014-04-01T20:08:03.727" Score="6" ViewCount="4002" Body="&lt;p&gt;I have X-Plane 10 with Boeing 777 Worldliner Pro- Extended Pack, which is designed to model the real-world operation of the 777.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does the AP never go to the heading hold direction even if I press the hold button?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XTvcw.png&quot; alt=&quot;snapshot of the game&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1964" LastEditorUserId="97" LastEditDate="2014-04-05T05:38:50.997" LastActivityDate="2018-02-06T12:28:51.030" Title="How to hold the heading on the Boeing 777 autopilot?" Tags="&lt;autopilot&gt;&lt;boeing-777&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2959" PostTypeId="1" CreationDate="2014-04-01T20:33:11.590" Score="19" ViewCount="928" Body="&lt;p&gt;When coming in on an instrument approach at a nontowered airport, the approach/center controller will clear you for the approach and approve your frequency change to the CTAF.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you're cleared for a particular approach and have changed frequencies, if you later decide you need to deviate from the planned approach (i.e. sidestep or circle instead of straight-in) do you need to get a revised clearance from the approach controller or is clearance for sidestep or circling implied?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1696" LastEditDate="2015-02-17T16:44:36.923" LastActivityDate="2015-02-17T16:44:36.923" Title="Do you need clearance from ATC to switch to a different approach at non-towered airport?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;non-towered-airport&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2960" PostTypeId="5" CreationDate="2014-04-01T21:16:03.860" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-01T21:16:03.860" LastActivityDate="2014-04-01T21:16:03.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2961" PostTypeId="4" CreationDate="2014-04-01T21:16:03.860" Score="0" Body="Airplane cabins are pressurized so that the air inside remains breathable at high altitudes." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-01T21:45:01.020" LastActivityDate="2014-04-01T21:45:01.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2964" PostTypeId="1" AcceptedAnswerId="2973" CreationDate="2014-04-01T21:48:37.663" Score="10" ViewCount="591" Body="&lt;p&gt;Aircraft can be brought into the US and be made airworthy by FAA standards. What about aircraft legally modified in other countries?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, there is a new &lt;a href=&quot;http://www.cessna-rotax.com/&quot;&gt;STC to put a Rotax 912 into Cessna 150s&lt;/a&gt; approved by the EASA. Can that STC be made legal in the US even though no similar STC exists here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, is this just due to relations between the EASA and FAA, or can this be done with aircraft coming from anywhere?&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-04-01T21:55:34.080" LastActivityDate="2017-12-15T16:25:50.810" Title="Can a modified aircraft be imported and certified in the US?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;easa-regulations&gt;&lt;modifications&gt;&lt;stc&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2965" PostTypeId="2" ParentId="2952" CreationDate="2014-04-01T22:01:20.733" Score="5" Body="&lt;p&gt;First, yes, it is entirely possible to fly under the coverage area of most civil radar systems. Other have already explained that in detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are radar systems that are not so limited by line of sight, and are able to see &lt;a href=&quot;http://en.wikipedia.org/wiki/Over-the-horizon_radar&quot;&gt;Over the Horizon&lt;/a&gt; using various techniques. So just because you're out of or below the range of the far-away radar does not mean that no one is watching you.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-01T22:01:20.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2966" PostTypeId="2" ParentId="2952" CreationDate="2014-04-02T00:31:27.550" Score="8" Body="&lt;p&gt;It also depends on the premise of the radar system. The civilian ATC radar system is based on the targets being cooperative (transponders) and they actually want certain aircraft to be invisible:  private aircraft not using controlled airports, for example. The system also deliberately removes slow-moving targets like flocks of birds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military radars, of course, assume the opposite. They deal with the line-of-sight problem with remote installations (e.g. &lt;a href=&quot;https://en.wikipedia.org/wiki/DEW_line&quot; rel=&quot;nofollow&quot;&gt;DEW line&lt;/a&gt;), over-the-horizon systems that can boil water at short ranges, and during a battle will put the radar station overhead (&lt;a href=&quot;https://en.wikipedia.org/wiki/Airborne_early_warning_and_control&quot; rel=&quot;nofollow&quot;&gt;AWACS&lt;/a&gt;). Mounting your radar antenna at 30,000 feet will extend its range a &lt;em&gt;long&lt;/em&gt; way, and make it both harder to blow up and easier to replace.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1696" LastEditDate="2014-04-04T15:00:00.633" LastActivityDate="2014-04-04T15:00:00.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2967" PostTypeId="5" CreationDate="2014-04-02T02:13:30.077" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-02T02:13:30.077" LastActivityDate="2014-04-02T02:13:30.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2968" PostTypeId="4" CreationDate="2014-04-02T02:13:30.077" Score="0" Body="A Supplemental Type Certificate is an FAA approved major modification or repair to an existing type certified aircraft, engine or propeller." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-02T02:16:23.390" LastActivityDate="2014-04-02T02:16:23.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2969" PostTypeId="5" CreationDate="2014-04-02T03:08:18.860" Score="0" Body="&lt;p&gt;FAA Flight Standards District Offices (FSDOs) are regional offices of the FAA.&lt;br&gt;&#xA;They perform a number of functions, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airworthiness certificates&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/forms/index.cfm/go/document.information/documentID/185675&quot; rel=&quot;nofollow&quot;&gt;Form 337&lt;/a&gt; approvals&lt;/li&gt;&#xA;&lt;li&gt;Air carrier certification and operations&lt;/li&gt;&#xA;&lt;li&gt;Permits (special flight permits, etc.&lt;/li&gt;&#xA;&lt;li&gt;Certification (licensing) for pilots, mechanics, repairmen, dispatchers, and parachute riggers&lt;/li&gt;&#xA;&lt;li&gt;Accident/Incident reporting&lt;/li&gt;&#xA;&lt;li&gt;Aircraft maintenance&lt;/li&gt;&#xA;&lt;li&gt;Enforcement of Airmen &amp;amp; Aircraft Regulations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can find contact information for your local FSDO &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot; rel=&quot;nofollow&quot;&gt;using this web page&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-04-02T03:08:18.860" LastActivityDate="2014-04-02T03:08:18.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2970" PostTypeId="4" CreationDate="2014-04-02T03:08:18.860" Score="0" Body="Questions about FAA Flight Standards District Offices (FSDOs) - including how to contact the appropriate group, and advice on phrasing requests/finding precedents" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-04-02T03:08:18.860" LastActivityDate="2014-04-02T03:08:18.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2971" PostTypeId="1" AcceptedAnswerId="2974" CreationDate="2014-04-02T03:09:43.880" Score="3" ViewCount="907" Body="&lt;p&gt;Is it technically feasible to make a &lt;a href=&quot;http://windward-performance.com/sparrowhawk/features/&quot; rel=&quot;nofollow&quot;&gt;sailplane&lt;/a&gt; from &lt;a href=&quot;http://www.aliexpress.com/item/2011-NEW-Transparent-color-Carbon-Fiber-Vinyl-Car-Sticker-1-27-30M-Roll/460912956.html&quot; rel=&quot;nofollow&quot;&gt;transparent carbon fiber&lt;/a&gt;? I am looking for an answer based on the specifications' comparison of the 2 different fibers.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And can it be made self-launch capable with an electric motor ? ie. the difference in the design considerations while positioning and designing an electric motor for a normal glider vs a carbon fiber glider; Eg. Sparrowhawk.&lt;/p&gt;&#xA;" OwnerUserId="1953" LastEditorUserId="6919" LastEditDate="2015-05-19T00:28:31.587" LastActivityDate="2015-05-19T00:28:31.587" Title="Can one make an electric-sailplane from transparent carbon fiber?" Tags="&lt;aircraft-design&gt;&lt;glider&gt;&lt;modifications&gt;&lt;aerospace-materials&gt;" AnswerCount="1" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="2972" PostTypeId="2" ParentId="2549" CreationDate="2014-04-02T03:28:12.997" Score="-2" Body="&lt;p&gt;Without even looking at the winds I'd just add something like 20 kts ground speed if going east and subtract 20 kts ground speed if going west. Amazing how often that came close enough to actual flight plan.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2014-04-02T03:28:12.997" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="2973" PostTypeId="2" ParentId="2964" CreationDate="2014-04-02T03:32:52.820" Score="6" Body="&lt;p&gt;Well, pretty much &lt;em&gt;anything&lt;/em&gt; can be given a US airworthiness certificate provided it's not &lt;em&gt;literally&lt;/em&gt; falling to pieces.  You could certificate such an aircraft as a &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/&quot; rel=&quot;noreferrer&quot;&gt;Special Airworthiness Certificate in the Experimental category&lt;/a&gt; -- Specifically one of:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Experimental -- Research and Development&lt;/strong&gt;&lt;br&gt;&#xA;  To conduct aircraft operations as a matter of research or to determine if an idea warrants further development.  Typical uses for this certificate include new equipment installations, operating techniques, or new uses for aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Experimental -- Showing compliance with regulations&lt;/strong&gt;&lt;br&gt;&#xA;  To show compliance to the airworthiness regulations when an applicant has revised the type certificate design data or has applied for a supplemental type certificate or field approval.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If your goal is to ultimately get this aircraft a &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/std_awcert/&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Standard airworthiness certificate&lt;/em&gt;&lt;/a&gt; you would probably want the latter, to allow you to conduct test/certification flights in the modified aircraft.&lt;br&gt;&#xA;To then get a standard airworthiness certificate things are a bit more murky. You could get a US STC based on the European STC &amp;amp; using this aircraft as the example for conformity inspections and flight testing, but that would require going through &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/stc/stc_app/&quot; rel=&quot;noreferrer&quot;&gt;the STC process&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other option would be the 337 process, in which case you are also going to need an A&amp;amp;P mechanic (preferably one with Inspection Authorization) and the cooperation of your local FSDO to approve the modification as a &quot;major alteration&quot; (&lt;a href=&quot;http://www.faa.gov/forms/index.cfm/go/document.information/documentID/185675&quot; rel=&quot;noreferrer&quot;&gt;FAA Form 337&lt;/a&gt; - Instructions &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.9-1F.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you alluded to in your question, something like installing a Rotax engine in a Cessna 150 is a &quot;Major Modification&quot; that has no &quot;FAA Approved Data&quot; (STC procedure/drawings/etc.) to include with the 337, so you would need to submit &quot;Acceptable Data&quot; for your modification (the European STC is a good starting point) and work with the FAA to obtain approval for the modification.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is something you would want to talk to the FAA about &lt;strong&gt;&lt;em&gt;before&lt;/em&gt;&lt;/strong&gt; purchasing an aircraft with such a modification (there's a good chance they may not approve the modification, which would leave you with an unairworthy aircraft, or one restricted to the Experimental category).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-02T03:32:52.820" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2974" PostTypeId="2" ParentId="2971" CreationDate="2014-04-02T04:00:08.233" Score="5" Body="&lt;p&gt;As long as there are load-bearing structures beneath the fiber (I don't know how strong that fiber is so I will assume it is fabric-like), it will most likely fly if designed properly. If the fiber is smooth, it shouldn't be much different than regular fabric or other composite skins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, there are plenty of sailplanes that self launch with electric or gas motors. You would just have to take into account the weight and position of the motor when you add it in. This could mean that you need to lengthen the tail section for more tail down force, move the seats further back, place the engine in a more neutral CG position above the fuselage on a pylon, or any number of other methods. You might then also need to increase the wing surface area a bit, to lift the extra weight. Also take into account the weight and position of the batteries. The design effects and considerations are pretty straightforward, but dealing with them may or may not be complicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Soviets tried in the 1930's to make an invisible spy plane (an AIR-6 I believe) by replacing the cloth skin with a cellophane-like material so that its entire was transparent. At just a few thousand feet the engine could be heard but the plane was almost completely invisible. Unfortunately the cellophane-like material would rapidly degrade after a few flights or several days out in the sun. It seems like your idea would be the modern version of that endeavor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nviQ7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-04-02T06:03:21.147" LastActivityDate="2014-04-02T06:03:21.147" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2975" PostTypeId="2" ParentId="2485" CreationDate="2014-04-02T04:01:09.547" Score="11" Body="&lt;p&gt;The primary concern is the increased landing distance due to the increased &lt;em&gt;ground speed&lt;/em&gt;. Landing &amp;amp; stopping distances increase more-than-linerally with each knot increase in ground speed. Given other dynamics of a landing aircraft this can be the straw that breaks the camel's back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The perfect storm&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;True story. C-141 on approach with a tail wind - not so bad by itself. Add in a 7,000-ish foot runway and &lt;em&gt;indicated airspeed&lt;/em&gt; a little high. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The aircraft didn't want to land so to speak because of the increased lift &lt;em&gt;due to excessive indicated airspeed&lt;/em&gt;. Also any gust (differential) is added to approach speed. In other words, the plane could not get into a landing attitude due to excess lift.&lt;/li&gt;&#xA;&lt;li&gt;Flying over the ground even faster due to 1, above, and the &lt;em&gt;tailwind induced ground speed&lt;/em&gt; increase.&lt;/li&gt;&#xA;&lt;li&gt;Pilot realizes he's floating too much and pushes down to get the plane on the ground.&lt;/li&gt;&#xA;&lt;li&gt;Nose wheel touches down - but not the mains! Pilots don't realize this. &lt;/li&gt;&#xA;&lt;li&gt;Pilot applies brakes and nothing happens, the mains still in the air and all. Panic begins.&lt;/li&gt;&#xA;&lt;li&gt;The end of the runway is getting closer and the pilot aggressively applies the brakes.&lt;/li&gt;&#xA;&lt;li&gt;The mains touch down and tires immediately begin to blow out, due the locked brakes.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft is departing center line due to tires blown out on one side.&lt;/li&gt;&#xA;&lt;li&gt;Pilot struggles to maintain control as the aircraft nears the end of the runway.&lt;/li&gt;&#xA;&lt;li&gt;Still too fast for safe taxiing, pilot attempts to turn the aircraft onto the last taxi way before the end of the runway.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft nose is turning but momentum, excess speed, drag from blown tires, differential braking - plane now slides sideways.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft stops just off of the end of the runway facing 90 degrees.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft catches on fire. That it's on the side of the blown tires and dragging strut is no surprise.&lt;/li&gt;&#xA;&lt;li&gt;Everyone gets out safely.&lt;/li&gt;&#xA;&lt;li&gt;NOTAM issued warning aircraft to beware the burned out hulk at the end of the runway. Adjust TakeOff and Landing Data accordingly.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;And the worst part of all of this?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It was to be the aircraft commander's &quot;fini flight&quot; - his last (multi stop) mission before leaving the Air Force. And so it was, only more so.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1798" LastEditorUserId="1798" LastEditDate="2014-04-03T00:23:46.457" LastActivityDate="2014-04-03T00:23:46.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2976" PostTypeId="2" ParentId="2959" CreationDate="2014-04-02T06:20:23.727" Score="6" Body="&lt;p&gt;Quoted from the Instrument Procedures Handbook, page 4-6:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;APPROACH CLEARANCE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The approach clearance provides guidance to a position&#xA;  from where you can execute the approach, and it also&#xA;  clears you to fly that approach. If only one approach pro-&#xA;  cedure exists, or if ATC authorizes you to execute the&#xA;  approach procedure of your choice, the clearance may&#xA;  be worded as simply as “… cleared for approach.” If&#xA;  ATC wants to restrict you to a specific approach, the&#xA;  controller names the approach in the clearance—for&#xA;  example, “…cleared ILS Runway 35 Right approach.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When the landing will be made on a runway that is not&#xA;  aligned with the approach being flown, the controller&#xA;  may issue a circling approach clearance, such as&#xA;  “…cleared for VOR Runway 17 approach, circle to land&#xA;  Runway 23.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if they name the approach, you are restricted to that approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I searched the rest of the book for items specifically related to non-towered operations, and found nothing that contradicted that.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-04-02T06:20:23.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2977" PostTypeId="1" CreationDate="2014-04-02T07:29:00.867" Score="12" ViewCount="2316" Body="&lt;p&gt;So the answer in my mind is &quot;of course pilots can fly circling approaches at non-towered airports&quot; (seriously, I could swear that I've done it before, but then again I can't think of any specific examples....).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is, until I ran across this little tidbit in the Air Traffic Control Order while researching another question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0408.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;4-8-6. CIRCLING APPROACH&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Circling approach instructions may only be given for aircraft landing at airports with operational control towers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So then the question becomes, why do they have circling minimums at non-towered airports??&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KfRhw.png&quot; alt=&quot;KBRY minimums&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No tower here.  &lt;/li&gt;&#xA;&lt;li&gt;ATC can't clear me to circle.  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Why do we have circling minimums??&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="14957" LastEditDate="2016-10-19T17:54:44.733" LastActivityDate="2016-10-20T09:41:53.123" Title="Can pilots fly circling approaches at non-towered airports?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;iaps&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2978" PostTypeId="2" ParentId="2485" CreationDate="2014-04-02T09:28:14.613" Score="5" Body="&lt;p&gt;To answer in part the question of how tailwinds are sometimes mitigated, an air carrier's op specs will typically specify how much of a tailwind is allowed for their operations. The two 747 carriers I flew for allowed a max tailwind of 10 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether a captain should choose to land given the max tailwind can be a complicated call. For example, runway 02 at Nadi, Fiji is about 9,000 feet, which makes it a bit of a short field operation for a 747 landing at or near max landing weight, a common occurrence with freighters. In the instance I'm thinking of, we were well inside the outer marker when the tower told us the wind had switched and that there was now a 10 knot tailwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I chose to land and here's why:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To have gone around would have meant involving ourselves further with the thunderstorms around the field.&lt;/li&gt;&#xA;&lt;li&gt;There was no guarantee that when we approached from the opposite end the wind would not have switched again and we would again be landing with a tailwind.&lt;/li&gt;&#xA;&lt;li&gt;Having landed there many times, I knew our spot on the ramp was very close to the end of the runway, there would be less than a minute of taxi time.&lt;/li&gt;&#xA;&lt;li&gt;I knew the Nadi ground service people were used to using a huffer on hot freighter brakes.&lt;/li&gt;&#xA;&lt;li&gt;I told the flight engineer to call the ground service people and tell them that we would have very hot brakes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;747 tires have 225 psi tires filled with nitrogen, and each tire has a thermal plug that will blow before a tire does. The QRH for handling hot brakes included instructions to warn the ground crew not to stand to the side of the tires, but the Nadi people were well aware of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All brake temperature gauges went into the red. I got out of the airplane as quickly as possible to take a look. They already had a huffer on each side of the airplane blowing on the brakes.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-04-02T09:28:14.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2979" PostTypeId="2" ParentId="2873" CreationDate="2014-04-02T10:52:20.940" Score="13" Body="&lt;p&gt;Following in the line of reasoning presented by &lt;code&gt;MSalters&lt;/code&gt; I would like to add a couple of points.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First of all there is no market pressure for the interfaces to become simple. With cars, boats and other vehicles 'normal' users with minimal training should be able to control them, thus car and boat manufacturers are motivated to make their product as simple as possible to understand. Some do this better than others, but comparing the middle dashboard of old cars with new cars there has been quite a change. In contrast with airplanes, put bluntly, it has already been accepted that a pilot needs &lt;strong&gt;a lot&lt;/strong&gt; of training, so the strong pressure to simplify control and offload work to a computer (from function to task oriented) is simply not there.&lt;/li&gt;&#xA;&lt;li&gt;Secondly aviation has to live with huge safety expectations. One of the results of this is - according to just a single expert I discussed this with... - that in the development of airplanes changing hardware/software on the control side is not done except if absolutely necessary. Why change something that's working? (even if it's as hole ridden as dutch cheese) And how can you change it if there is a huge checklist of things a human pilot is expected (legally) to do (regardless of a computer being better suited to the task).&lt;/li&gt;&#xA;&lt;li&gt;And lastly, as pilots have received such exhaustive training it is even harder to innovate in the field, as people who have spend a lot of time on learning something are all the less likely to give it up. Thus making a plane which could be learned to pilot in half the time would be senseless as seniors would refuse to pilot it and juniors would still know how to pilot the old planes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Oh well, just a few thoughts from the UX/market perspective.&lt;/p&gt;&#xA;" OwnerUserId="1368" LastActivityDate="2014-04-02T10:52:20.940" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="2980" PostTypeId="1" AcceptedAnswerId="2989" CreationDate="2014-04-02T11:42:08.140" Score="18" ViewCount="2188" Body="&lt;p&gt;I recently came across some slides from a flight school teaching, for the initial climb after take-off and for the approach, the strategy of controlling/adjusting&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;RoC/RoD with &lt;strong&gt;power&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Speed with &lt;em&gt;attitude&lt;/em&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I tried to inform myself a bit on the subject, because I am more familiar with the idea of controlling  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;RoC/RoD with &lt;em&gt;attitude&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Speed with &lt;strong&gt;power&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I came to understand that this is mostly a difference between VFR vs IFR flight.&#xA;Is this true?&#xA;Does the first approach actually have benefits in terms of ability for the pilot to control the plane in VFR flight? If yes, how and which?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="72" LastEditDate="2014-04-05T15:59:39.153" LastActivityDate="2015-09-17T23:41:43.247" Title="Airplane longitudinal control: pitch or power?" Tags="&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;&lt;flight-controls&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="2981" PostTypeId="2" ParentId="2977" CreationDate="2014-04-02T12:26:58.393" Score="1" Body="&lt;p&gt;As I understand &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;nofollow&quot;&gt;5-4-20&lt;/a&gt; circling minima provide obstacle clearance within a lateral distance of the runway. In certain circumstances it may be necessary to overfly the landing environment to establish winds, etc. This should only be done when the pattern is in VFR conditions. 4-8-6 applies to clearances given not necessarily all safe operations.  &lt;/p&gt;&#xA;" OwnerUserId="1977" LastEditorUserId="1977" LastEditDate="2015-02-10T13:46:39.213" LastActivityDate="2015-02-10T13:46:39.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2982" PostTypeId="1" CreationDate="2014-04-02T13:05:54.020" Score="4" ViewCount="160" Body="&lt;p&gt;In Rickenbacher's autobiography he tells of his flight across the Atlantic in a B-17 after WWII. They ended up running out of gas as I recall, making a water landing in the middle of the ocean. They were stranded for about a month before being rescued.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the early post-WWII era, how was it that they were able to find him at all? What factors contributed?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="97" LastEditDate="2014-04-03T04:09:06.250" LastActivityDate="2014-04-03T04:09:06.250" Title="What factors contributed to enable Rickenbacher to be found?" Tags="&lt;search-and-rescue&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2984" PostTypeId="2" ParentId="2982" CreationDate="2014-04-02T13:22:18.943" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Eddie_Rickenbacker#Adrift_at_sea&quot; rel=&quot;nofollow&quot;&gt;Actually&lt;/a&gt; it was during WW2 and it was the Pacific:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of Rickenbacker's most famous near-death experiences occurred in October 1942 [...] The bomber strayed hundreds of miles off course while on its way to a refueling stop on Canton Island and was forced to ditch in a remote and little-traveled part of the Central Pacific Ocean.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not familiar with the episode, and &lt;a href=&quot;http://www.americanheritage.com/articles/magazine/ah/2008/5/2008_5_40.shtml&quot; rel=&quot;nofollow&quot;&gt;this source&lt;/a&gt; is currently not working for me, but from the little information that the wiki reports, I have the impression that the main factor has been pure luck.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-04-02T13:22:18.943" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2986" PostTypeId="5" CreationDate="2014-04-02T14:00:01.367" Score="0" Body="&lt;p&gt;Pilots record - or &lt;em&gt;log&lt;/em&gt; - their flights for various reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Student pilots start logging their flight time because most countries require a minimum number of hours spent flying in various conditions before the student is allowed to take the final flight test. The logbook proves to the examiner that they have flown the required amount of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After that, most pilots continue logging their flight time for a variety of reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For personal information and satisfaction&lt;/li&gt;&#xA;&lt;li&gt;For advanced certifications that also require minimum flight times&lt;/li&gt;&#xA;&lt;li&gt;To document currency (e.g. night currency, instrument currency)&lt;/li&gt;&#xA;&lt;li&gt;For insurers who require minimum flight times&lt;/li&gt;&#xA;&lt;li&gt;For employers who require detailed logs of flight time&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Many pilots keep a paper logbook, but electronic logging tools are now common. In some countries (like the USA) an instructor must endorse (sign) a logbook to certify that a student has completed certain tasks or reached certain goals; this is almost always done on paper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no international standard or format for logging flight time, and private pilots can use any format they choose. Professional pilots often have to submit logs to their employer in a specific format, in addition to any personal log they might have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft, engines and sometimes avionics systems also have logbooks that record maintenance, repairs, software updates, compliance with safety directives and other essential information. Because these logs provide the complete history of the aircraft, they're usually the first thing to check when buying a second-hand aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about how pilots log their flying time; maintaining aircraft or engine logs; legal requirements for logging etc.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_logbook&quot; rel=&quot;nofollow&quot;&gt;Pilot logbook&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="62" LastEditDate="2015-07-23T18:15:12.510" LastActivityDate="2015-07-23T18:15:12.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="2987" PostTypeId="4" CreationDate="2014-04-02T14:00:01.367" Score="0" Body="Use for logbooks and logging hours" OwnerUserId="72" LastEditorUserId="14897" LastEditDate="2021-05-06T22:57:12.243" LastActivityDate="2021-05-06T22:57:12.243" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="2988" PostTypeId="1" AcceptedAnswerId="2990" CreationDate="2014-04-02T14:24:53.853" Score="4" ViewCount="776" Body="&lt;p&gt;Is Jet-A used in turbojets or is it just used in turbofans, turboprops, and the SMA SR305-230 for Cessna? &lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="580" LastEditDate="2014-04-02T14:52:21.690" LastActivityDate="2017-05-11T21:47:42.300" Title="Which engines are Jet-A used in?" Tags="&lt;fuel&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2989" PostTypeId="2" ParentId="2980" CreationDate="2014-04-02T14:38:04.940" Score="21" Body="&lt;p&gt;I was wondering how long that it would take for this question to come up.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the old &quot;pitch -vs- power&quot; airspeed control technique debate that rages throughout the aviation world.  There are &lt;strong&gt;strong&lt;/strong&gt; proponents of both techniques (and they seem to view it almost as a religious debate in that the other side can never be right, &lt;strong&gt;&lt;em&gt;no matter what&lt;/em&gt;&lt;/strong&gt;), and both sides have good reasons for it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of saying that one is better than the other, let's just say that they are both techniques for managing the potential energy of the airplane (the airspeed that can be traded for altitude and vice-versa).  In fact, this is how I like to think about it (and don't pick a side):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you change the pitch of the aircraft without changing power, the airspeed will stabilize out at a new value.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pitch up and you lower the airspeed.&lt;/li&gt;&#xA;&lt;li&gt;Pitch down and you raise the airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;If you change the power setting of the aircraft without changing the pitch, the airspeed will stabilize out at a new value.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Add power and you raise the airspeed.&lt;/li&gt;&#xA;&lt;li&gt;Reduce power and you lower the airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You can change both at the same time and get various results.&lt;br&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You can end up with the same airspeed that you had before.&lt;/li&gt;&#xA;&lt;li&gt;You can end up with a &lt;strong&gt;lot&lt;/strong&gt; more airspeed.&lt;/li&gt;&#xA;&lt;li&gt;You can end up with a &lt;strong&gt;lot&lt;/strong&gt; less airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most often you need to change both at the same time in order to properly manage your airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically it comes down to what you want to accomplish.  If you need to change the airspeed you have two ways to do it, but used individually each comes with a side-effect.  In some situations this may be okay or even desirable, but you need to be aware of what your actions are going to accomplish.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Let's look at a specific example:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes, especially on an instrument approach, you want to maintain your current airspeed while changing your vertical speed.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Let's say that you are a little high on the glideslope.&lt;br&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you simply pitch down to recapture the glideslope, you will gain airspeed but will recapture it quickly.&lt;/li&gt;&#xA;&lt;li&gt;If you simply reduce the power to recapture the glideslope, you will lose airspeed but it will take longer than using pitch.&lt;/li&gt;&#xA;&lt;li&gt;If you want to maintain your airspeed while recapturing the glideslope (typical on an instrument approach) then you would pitch down and reduce power at the same time, and when you recapture the glideslope you will pitch back up to maintain it and add power to maintain your current airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-03T02:26:49.257" LastActivityDate="2014-04-03T02:26:49.257" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="2990" PostTypeId="2" ParentId="2988" CreationDate="2014-04-02T14:47:10.830" Score="6" Body="&lt;p&gt;Jet-A is mostly for turbine engines in general. Turbine engines can be fueled with nearly anything that you can spray over an open flame and will burn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not a substitute for avgas, for the same reasons that diesel is not a substitute for petrol. You can fuel a diesel engine with Jet-A under some circumstances.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-02T15:16:18.580" LastActivityDate="2014-04-02T15:16:18.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2991" PostTypeId="1" AcceptedAnswerId="2992" CreationDate="2014-04-02T17:30:11.873" Score="21" ViewCount="31048" Body="&lt;p&gt;Below the &lt;em&gt;transition altitude&lt;/em&gt; (18,000 feet in the US), pilots use &lt;em&gt;local pressure&lt;/em&gt; readings to calibrate their altimeters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above the &lt;em&gt;transition altitude&lt;/em&gt;, pilots set a &lt;em&gt;standard pressure&lt;/em&gt; to calibrate the altimeter. The standard pressure is 29.92 inches of mercury or 1013 hPa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where did this value come from?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-16T16:15:32.807" LastActivityDate="2017-06-16T01:22:45.327" Title="Where did the standard pressure 29.92&quot; come from?" Tags="&lt;flight-instruments&gt;&lt;altimeter&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2992" PostTypeId="2" ParentId="2991" CreationDate="2014-04-02T17:47:32.780" Score="19" Body="&lt;p&gt;It is called &quot;standard pressure&quot; because 29.92 In-Hg (or 1013.25 hPa) is the standard atmospheric pressure at sea level according to both the &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Standard_Atmosphere&quot;&gt;ISA&lt;/a&gt; (International Standard Atmosphere) and the &lt;a href=&quot;http://en.wikipedia.org/wiki/U.S._Standard_Atmosphere&quot;&gt;US 1976 Standard Atmosphere&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below 18,000ft, local altimeter settings are used because you need to know how high you are above terrain, or whether or not you're at the proper altitude for an instrument approach, or at pattern altitude, etc. In cruising flight above 18,000ft, except for a few places in the world, you are well above any terrain, so errors in actual altitude of even a couple thousand feet is unlikely to cause a problem. In this case, having all airplanes use a common altimeter setting is useful because it 1. doesn't require you to change it frequently as you pass through changes in pressure, and 2. it helps ATC ensure separation without having to inform flights every 10 minutes of a new setting. It makes sense to use standard pressure in this case because it represents a good baseline average, and you may have noticed that reported altimeter settings tend to average around 29.92 anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, there are instances where you may still need to know the en-route altimeter settings for flight planning purposes. Suppose the minimum safe altitude along your route is 19,000 ft MSL and current pressure is 29.42. If you decided to cruise at FL190, you would actually be flying at about 18,500ft MSL, and would be below your minimum safe altitude. Colder than standard temperature can have similar effect as low pressure, and will result in the airplane being lower than the indicated altitude.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2014-04-02T19:18:23.940" LastActivityDate="2014-04-02T19:18:23.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2993" PostTypeId="2" ParentId="2980" CreationDate="2014-04-02T18:11:41.167" Score="10" Body="&lt;p&gt;The practical argument for teaching the first approach to ab-initio students concerns developing safe responses to problems:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Falling short on approach (too high a rate of descent): If your first reaction is to raise the nose, you may well be creating the more dangerous 'too slow on approach' situation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Power failure: If you think power controls speed, then you have lost the ability to maintain the correct speed. Furthermore, raising the nose will not keep you in the air (though it will slow you down).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;From a more theoretical point of view, what does power allow a powered aircraft do that a glider cannot? It allows it to gain and maintain altitude relative to the airmass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This point of view works well for flying small, low-powered, single-engined airplanes in VMC; beyond that, I cannot say.&lt;/p&gt;&#xA;" OwnerUserId="1981" LastActivityDate="2014-04-02T18:11:41.167" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="2994" PostTypeId="1" AcceptedAnswerId="3029" CreationDate="2014-04-02T18:33:28.983" Score="7" ViewCount="2751" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What should a pilot do to perform a successful &lt;strong&gt;emergency water landing&lt;/strong&gt;, also known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Water_landing&quot; rel=&quot;noreferrer&quot; title=&quot;Ditching&quot;&gt;ditching&lt;/a&gt; of a big commercial jet?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there any checklist, or best practices, like &lt;em&gt;&quot;elevate the nose&quot;&lt;/em&gt; or &lt;em&gt;&quot;retract the landing gear&quot;&lt;/em&gt;, to make it safer? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are commercial Jets buoyant?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flightglobal.com/blogs/wp-content/uploads/mt/flightglobalweb/blogs//learmount/Ditching.jpg&quot; rel=&quot;noreferrer&quot;&gt;ditching http://www.flightglobal.com/blogs/wp-content/uploads/mt/flightglobalweb/blogs//learmount/Ditching.jpg&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="1700" LastEditDate="2014-04-03T11:57:09.813" LastActivityDate="2014-04-03T15:35:57.127" Title="What should a pilot do to perform a successful emergency water landing?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;ditching&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="2995" PostTypeId="2" ParentId="2980" CreationDate="2014-04-02T18:41:13.730" Score="7" Body="&lt;p&gt;Due to longitudinal stability, aircraft tends to maintain constant angle of attack. In straight flight the wing loading is constant, so speed remains the only significant factor and the aircraft tends to maintain constant speed (or rather oscillate around it in &lt;a href=&quot;http://en.wikipedia.org/wiki/Phugoid&quot;&gt;phugoid oscillation&lt;/a&gt;). If you increase the power and speed is maintained, law of conservation of energy dictates that the aircraft has to climb and when power is reduced it has to descend. So in theory you control speed with elevator (and trim so it is maintained without pressure on the controls) and vertical speed with power. See &lt;a href=&quot;http://www.av8n.com/how/htm/aoa.html&quot;&gt;How It Flies, chapter 2&lt;/a&gt; for a detailed discusson.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice changing power affects pitch trim too, so you need to always adjust both. And you have to arrest the phugoid oscillation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It might be interesting to note that Airbus control laws change the rules so that attitude controls climb/descent and power controls speed by automatically adjusting the trim.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-04-03T07:45:39.317" LastActivityDate="2014-04-03T07:45:39.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2996" PostTypeId="1" AcceptedAnswerId="2997" CreationDate="2014-04-02T18:55:57.470" Score="13" ViewCount="3075" Body="&lt;p&gt;I was reading some forum about funny ATC communications and one commentary was&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;GXXXX: Request status of danger areas X1, 2 and 4&lt;br /&gt;&#xA;&amp;lt;Pause&amp;gt;&lt;br /&gt;&#xA;London info: I don't recognise area number x124&lt;br /&gt;&#xA;GXXXX: My mistake I meant areas x1, x2 and X4&lt;br /&gt;&#xA;London info (female): Sorry, just had a blonde moment here&lt;/p&gt;&#xA;&lt;p&gt;(assume she was new and didn't know the non appologising [sic] rule)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.pprune.org/atc-issues/59309-atc-humour-merged-67.html#post5699168&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;when referring to some thing the ATC said, apologising for not understanding some non-formal phraseology.&lt;/p&gt;&#xA;&lt;p&gt;What is that rule ?&lt;/p&gt;&#xA;" OwnerUserId="616" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-04T16:10:58.807" Title="What is the &quot;non-apologizing rule&quot;?" Tags="&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="2997" PostTypeId="2" ParentId="2996" CreationDate="2014-04-02T19:24:29.477" Score="18" Body="&lt;p&gt;I suspect there is no such rule. I looked at a few online sources - none mention the word apology (or variants).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC communication is expected to be short and follow a standard set of stock phrase forms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything outside that is discouraged unless necessary to clarify instructions etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;FAA&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An FAA document &lt;em&gt;&quot;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html&quot;&gt;Radio Communications Phraseology and Techniques&lt;/a&gt;&quot;&lt;/em&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Brevity is important, and contacts should be kept as brief as possible, &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So any communication that doesn't follow one of the standard patterns is discouraged. It continues.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;but controllers must know what you want to do before they can properly carry out their control duties. And you, the pilot, must know exactly what the controller wants you to do. Since concise phraseology may not always be adequate, use whatever words are necessary to get your message across.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;ICAO&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An ICAO document &lt;em&gt;&quot;&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/115.pdf&quot;&gt;ICAO Standard Phraseology A Quick Reference Guide for Commercial Air Transport Pilots&lt;/a&gt;&quot;&lt;/em&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Phraseology has evolved over time and has been carefully developed to provide &#xA;  maximum clarity and brevity in communications while ensuring that phrases are &#xA;  unambiguous. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again the emphasis is on brevity and standard phraseology. It also continues ina similar way to the FAA document.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, while standard phraseology is available to cover most &#xA;  routine situations, not every conceivable scenario will be catered for and RTF &#xA;  users should be prepared to use plain language when necessary following the &#xA;  principle of keeping phrases clear and concise. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Other&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For non-pilot rubberneckers like me, a good intro to pilot-ATC communication is &lt;a href=&quot;http://www.avweb.com/news/sayagain/192912-1.html?redirected=1&quot;&gt;a &quot;Say Again&quot; blog post&lt;/a&gt; or &lt;a href=&quot;http://www.avweb.com/news/sayagain/190337-1.html?redirected=1&quot;&gt;Two&lt;/a&gt; by Don Brown.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I remember one time when I was a young controller and working a slow, high-altitude sector. I was bored so I got into a conversation with a pilot about something or other. All of a sudden I noticed this F-15 was in a big turn.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; &quot;Peach two one, Atlanta Center, where you goin'?&quot;  &#xA; &quot;Atlanta Center, Peach two one is declaring an emergency, &#xA;        we've lost an engine and are returning to Dobbins.&quot;  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;  &#xA;  &lt;p&gt;He couldn't get on the frequency because I was having a conversation. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-04-02T19:42:58.230" LastActivityDate="2014-04-02T19:42:58.230" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="2998" PostTypeId="2" ParentId="2991" CreationDate="2014-04-02T19:44:59.580" Score="11" Body="&lt;p&gt;It is called &quot;standard pressure&quot; because at an altitude of mean sea level (mean of all tides low to high) averaging the air pressure across equator to pole, winter to summer, over land and sea and day to night you get an average pressure that will register on the barometer at around 29.92 inches of mercury.&lt;/p&gt;&#xA;" OwnerUserId="1977" LastActivityDate="2014-04-02T19:44:59.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="2999" PostTypeId="1" AcceptedAnswerId="3001" CreationDate="2014-04-02T19:54:42.163" Score="39" ViewCount="63085" Body="&lt;p&gt;On an &lt;a href=&quot;https://aviation.stackexchange.com/a/2483/1983&quot;&gt;another question, an answer said&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You don't need an engine to fly as airplanes are designed to glide without it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I suspect this heavily depends on the type of the aircraft, so lets assume we are considering a small airplane.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How far could an airplane glide?&lt;/li&gt;&#xA;&lt;li&gt;What governs the &lt;em&gt;glideability&lt;/em&gt; of an airplane?&lt;/li&gt;&#xA;&lt;li&gt;Is it possible, for an airplane with an engine/engines, to leverage this to save fuel while flying, or are they too heavy/otherwise unable to do this?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1983" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-12-23T15:13:21.633" Title="How far can airplanes glide?" Tags="&lt;aircraft-design&gt;&lt;glide-ratio&gt;" AnswerCount="7" CommentCount="13" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3000" PostTypeId="2" ParentId="2999" CreationDate="2014-04-02T20:05:12.557" Score="8" Body="&lt;p&gt;Glide is measured in what's called &quot;glide ratio&quot;. For every foot of altitude the airplane loses, how far forward can it go? Sailplanes (gliders) have a glide ratio around 40 to 1. It can be much more or less, depending on the model. The glide ratio of the Cessna 172, the most popular single engine airplane, is about 10 to 1. The Boeing 767 that lost all power attained a glide ratio of about 12 to 1 in practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes generally do not use this to save fuel. It's much more efficient just to fly the airplane normally, or at low power if they are looking to conserve fuel. To glide would require turning the engine on and off. That is not efficient in jets, turboprops or piston engines. I believe some unmanned, high altitude aircraft may turn their engines off, though.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-04-02T20:05:12.557" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3001" PostTypeId="2" ParentId="2999" CreationDate="2014-04-02T20:05:16.000" Score="43" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I suspect this heavy depends on the type of the aircraft, so lets assume we are considering a small airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Absolutely right, it does vary widely. The parameter you're asking about is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift-to-drag_ratio#Glide_ratio&quot; rel=&quot;noreferrer&quot;&gt;glide ratio&lt;/a&gt; and it is directly related to another parameter called &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift-to-drag_ratio#Glide_ratio&quot; rel=&quot;noreferrer&quot;&gt;lift-to-drag ratio&lt;/a&gt; or &lt;strong&gt;L/D ratio&lt;/strong&gt;. This is a fundamental characteristic of the aerodynamics of a particular aircraft. L/D ratio varies with airspeed; for determining best engine-out glide performance, the L/D ratio at &quot;best glide airspeed&quot; is used. &quot;Best glide airspeed&quot; is the speed that maximizes the L/D ratio, and this maximum value is known as &lt;strong&gt;L/D&lt;sub&gt;max&lt;/sub&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum L/D ratio (L/D&lt;sub&gt;max&lt;/sub&gt;) of a Cessna 172 is about 9, so its glide ratio is about 9:1 - for every 9 units traveled forward it will lose 1 unit of altitude. So, it will glide about 9,000 feet for every 1,000 feet of altitude available. This is a fairly typical value for small planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To show you how widely variable this is, a modern glider can achieve ratios above 60:1, while the Space Shuttle ranged from about 1:1 at high speed, early in reentry, to 4.5:1 on final approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notably, large transport aircraft tend to have significantly higher L/D ratios than small aircraft: a 747 can achieve an L/D&lt;sub&gt;max&lt;/sub&gt; of about 17:1. With an altitude of 33,000 feet (~10,000 meters) that would mean a gliding distance of 100 miles (~170 Km).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What governs the 'glideability' of the plane?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As above, its lift-to-drag ratio. Very casually speaking this is just a measure of how &quot;aerodynamic&quot; the airplane is, comparing its capability to generate lift with the drag it creates in the process. The better its lifting capabilities, or the less drag it generates, the higher the ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, I highly recommend a free online book on aerodynamics called &lt;strong&gt;&lt;a href=&quot;http://www.av8n.com/how/&quot; rel=&quot;noreferrer&quot;&gt;See How It Flies&lt;/a&gt;&lt;/strong&gt; by John Denker. It is written for pilots, not mathematicians or physicists, so it explains the concepts very intuitively without a lot of equations. It talks about L/D ratio and explains some of the factors that affect it. (I would recommend this book to any pilot anyway.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible, for an airplane with an engine/engines, to leverage this to save fuel while flying, or are they too heavy/otherwise unable to do this?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since glide ratio is directly related to (indeed it's the same thing as) L/D ratio, you could say that airplanes already do take advantage of it. The higher their L/D at cruise airspeed, the more fuel-efficient they will be (because less thrust will be required to counteract drag in steady-state flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're asking about shutting the engines off during approach/landing to save fuel, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1906/is-landing-without-engine-power-routinely-feasible&quot;&gt;there is another question here on ASE&lt;/a&gt; which specifically addresses this. (The answer, in short, is no, it's not practical.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-08-30T04:33:15.300" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3002" PostTypeId="2" ParentId="2485" CreationDate="2014-04-02T20:32:33.450" Score="6" Body="&lt;p&gt;As others have highlighted, the question is with what ground speed you touch down. You might think that plus/minus a few knots doesn't really matter, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;your kinetic energy is quadratic in speed: E = 1/2 m v^2.&lt;/li&gt;&#xA;&lt;li&gt;if braking acceleration is constant, landing distance is quadratic in speed: s = v^2 / 2a&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, to adapt voretaq7's example, if your approach air speed is 45 knots, with a 15 knots headwind you land with 30 knots, while with a tailwind you land with 60 knots - now you touch down with &lt;strong&gt;four times the energy&lt;/strong&gt; you need to dissipate, and need &lt;strong&gt;four times as much runway&lt;/strong&gt; to stop (which, happily, lines up nicely with his POH numbers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, finally, one more example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose the runway is such that with no wind, you can land with approach speed v and just stop prior to the end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a (mild) headwind of 10% of your airspeed, you touch down with 0.9v, thus you now use only 81% of the available runway, and have gained quite a buffer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas, if you have a 10% tailwind, you touch down with 1.1v. Thus, your required stopping distance now is 1.21 times the available runway. When you hit the end now, you'd need 21% of the runway length extra to stop. Now, this gets a bit tricky, but feel free to do the maths, this means that you hit the wall at the end with nearly half of your approach speed, still having about 21% of your (1v) landing energy left to dissipate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So - what would you rather have, a 20% buffer of runway remaining (with head wind), or hitting the end of the runway with over 40% of your landing speed (with tail wind)? :-)&lt;/p&gt;&#xA;" OwnerUserId="1984" LastActivityDate="2014-04-02T20:32:33.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3003" PostTypeId="2" ParentId="2917" CreationDate="2014-04-02T21:06:33.557" Score="8" Body="&lt;p&gt;The answers given are correct for the USA. If you're in one of the other 199 (or so) countries, it's more likely that something closer to the original ICAO (International Civil Aviation Organisation) definition of airspace applies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They specify (a) what sort of traffic is allowed, and (b) who is responsible for avoiding other traffic, namely ATC (when separation is provided) or the pilot.&#xA;Below, IFR refers to Instrument Flight Rules, while VFR refers to Visual Flight Rules.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Class A: IFR only. All aircraft are subject to ATC clearance. All flights are separated from each other by ATC.&lt;/li&gt;&#xA;&lt;li&gt;Class B: IFR or VFR. All aircraft are subject to ATC clearance. All flights are separated from each other by ATC.&lt;/li&gt;&#xA;&lt;li&gt;Class C: IFR or VFR. All aircraft are subject to ATC clearance. IFR flights are separated from each other and from VFR, but VFR flights are not separated from each other.&lt;/li&gt;&#xA;&lt;li&gt;Class D: IFR or VFR. All flights are subject to ATC clearance. IFR flights are separated from each other, and are given traffic information in respect of VFR flights.&lt;/li&gt;&#xA;&lt;li&gt;Class E: IFR or VFR. IFR flights are subject to ATC clearance. IFR flights are separated from each other, and are given traffic information in respect of VFR flights.&lt;/li&gt;&#xA;&lt;li&gt;Class F: IFR or VFR (no SVFR). ATC separation will be provided, so far as practical, to aircraft operating under IFR. &lt;/li&gt;&#xA;&lt;li&gt;Class G: IFR or VFR (no SVFR). ATC separation is not provided. Traffic Information may be given as far as is practical in respect of other flights.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Individual countries can (unfortunately...) deviate quite substantially from these airspace classes, and/or impose further structure on top of them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Frequently, certain air space classes will have specific speed limits, equipment requirements, or minimum visibility requirements for VFR traffic.&lt;/p&gt;&#xA;" OwnerUserId="1984" LastActivityDate="2014-04-02T21:06:33.557" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3004" PostTypeId="2" ParentId="2485" CreationDate="2014-04-03T01:02:31.840" Score="2" Body="&lt;p&gt;With a really good headwind and a little bitty plane (Cessna 150) you can get your groundspeed down to a trot and and just set it on the ground.  Have done it at PDK in Atlanta, in March.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not do this with passengers. Safety is one reason.  Not terrifying them is another.&lt;/p&gt;&#xA;" OwnerUserId="1988" LastActivityDate="2014-04-03T01:02:31.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3005" PostTypeId="2" ParentId="2996" CreationDate="2014-04-03T01:19:05.447" Score="10" Body="&lt;p&gt;As far as I know, this is not an official rule, but I have heard about it in the past. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the 'rule' has its background in two principles:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, you keep communications efficient and short. Don't block the frequency unnecessary. Some countries have guidance in their ATC communication handbooks that discourage exchange of courtesies. Apologizing could be categorized as such. &#xA;For example: in the UK CAA has the following text in their CAP 413 Radiotelephony manual:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Avoid excessive use of courtesies and entering into non-operational&#xA;  conversations&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Secondly, you don't apologise for asking clarification on the frequency. It implies that you made a mistake. Making sure that the communication is clearly understood by both sides is an essential safety requirement and therefore asking clarification should never be apologised for because it is the only right thing to do when in doubt. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the context of the eternal pissing contest between pilots and controllers the above is sometimes reduced to following rules:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Never apologize on the frequency&lt;/li&gt;&#xA;  &lt;li&gt;Never call a pilot 'Sir'&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;It will make THEM feel superior.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-03T01:19:05.447" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3010" PostTypeId="2" ParentId="2977" CreationDate="2014-04-03T02:41:52.017" Score="4" Body="&lt;p&gt;The way I understand that ATC order is that it is about &quot;circling approach &lt;em&gt;instructions&lt;/em&gt;&quot; which is different than &quot;(circling) approach &lt;em&gt;clearance&lt;/em&gt;&quot;. They cannot tell you to enter a left downwind, do a right 360, or follow some other specific path to the runway. If they clear you to execute a circling approach to a given runway at a non-towered airport, then the path to the runway is for the pilot to determine, as necessary to separate yourself from other aircraft in the terminal area and land safely.&lt;/p&gt;&#xA;" OwnerUserId="1847" LastActivityDate="2014-04-03T02:41:52.017" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3011" PostTypeId="1" AcceptedAnswerId="3013" CreationDate="2014-04-03T02:47:59.453" Score="10" ViewCount="79148" Body="&lt;p&gt;This is confusing to me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since pressure increases with temperature (I don't know why), how can air density decrease with temperature. In a hot day then pressure would increase and air density decrease? How is that possible? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;@casey @steve V. @StallSpin&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point is this: FAA writtten says:&#xA;The altimeter will indicate lower altitude than actually flown in a temp warmer than standard. I understand that this way: this an example&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Indicated Altitude: 12.000ft&#xA;   True Altitude: 12.000ft&#xA;   Temperature: -9 Celsius (STD)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then suddenly the air temperature changes from -9 to +20 (Example) and in a couple of minutes we have: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indicated Altitude: 12.000ft&#xA;   True Altitude: 14.000ft&#xA;   (In warmer than stantard, pressure increases so the aneroid waffers in the altimeter will contract indicating lower altitude (lets say it indicated 10.000), then the pilot will climb &quot;back&quot; to 12.000 but in reality (true altitude) he is climbing to 14.000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I getting this right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Now another thing, temperature decreases with altitude, so aneroid waffers are expanded with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the aneroid waffers mesure density or pressure?&lt;/p&gt;&#xA;" OwnerUserId="1990" LastEditorUserId="1990" LastEditDate="2014-04-03T04:06:54.990" LastActivityDate="2018-04-09T19:34:13.013" Title="How is pressure related to air density?" Tags="&lt;density-altitude&gt;&lt;temperature&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3012" PostTypeId="2" ParentId="3011" CreationDate="2014-04-03T02:58:20.873" Score="4" Body="&lt;p&gt;A big thing to remember is that $Density=\frac{Mass}{Volume}$. It is unrelated to pressure, and pressure is unrelated to density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressure generally increases with temperature only in a gas with a constant volume. This is because you are adding more energy to the system, causing the molecules to become more exited. To put simply, they bounce around harder and exert more energy on each other and the walls of their container. We call that pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there were no container, an increase in temperature would cause the molecules to fly apart. Now there are less molecules per unit of volume, so the density is lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in aviation and meteorology when we talk about atmospheric pressure, that is slightly different, and is less related to atmospheric density. High and low pressure systems are more affected by relative upward and downward motion of huge air masses than by immediate local temperature, as a contained gas would be.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="97" LastEditDate="2014-04-17T02:11:43.740" LastActivityDate="2014-04-17T02:11:43.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3013" PostTypeId="2" ParentId="3011" CreationDate="2014-04-03T03:10:31.947" Score="11" Body="&lt;p&gt;The atmosphere approximates an ideal gas, and as such you can relate pressure and density through the ideal gas equation.  The form we use in meteorology uses mass density and is given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$p={\rho}RT$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $P$ is pressure in units of Pa, $\rho$ is density in units of kg m-3, $R$ is the gas constant for dry air (287 J kg-1 K-1) and $T$ is temperature in Kelvin.  This assumes a dry atmosphere and humidity will decrease density for a given pressure.  Consideration for water vapor is usually brought in by changing temperature into virtual temperature $T_V$ where $T_V=T(1+0.61q)$ and $q$ is the mixing ratio of water vapor (units $kg~ kg^{-1}$). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pressure increases with temperature because the particles have more kinetic energy (which is proportional to $T$).  Imagine a box full of bouncing balls, if these balls start moving faster the balls will hit the walls of the box harder, imparting more force on the box.  Pressure is merely force per area, so if the force increases but the box stays the same size, the pressure has increased.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Air density can decrease with temperature if pressure is also decreasing.  If pressure is constant, this cannot happen (they would be inversely related).  Any time you specify a relation between any two of pressure, density or temperature you must hold the third constant or specify its behavior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, hot air rises, but why then is it cold on top of a mountain.  The answer is that hot air is less dense than the cold air surrounding it for a constant pressure, and being less dense it rises.  With a mountain, the pressure is decreasing, and we likewise find in the atmosphere that temperature decreases with decreasing pressure.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On a hot day what tends to happen is that the surface, which is being warmed by the sun, heats the lowest level of the atmosphere, reducing its density (it is at the same pressure as its surroundings and its T rises).  This will eventually drive convection and mix this warmer air vertically.  Given enough time, this will reduce the mass in the column of air and therefore reduce the pressure at the surface.  These are called &quot;heat lows&quot; and you can see them forming in the desert areas and they play roles in sea breeze formation and the monsoons.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To address the expanded question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point in the FAA written is best understood by forgetting that we fly at constant altitudes -- we don't.  In level flight we fly on constant pressure surfaces which we then translate to an altitude.  In any given column of atmosphere, if it is warmer than standard a given pressure surface will be higher and when colder than standard the pressure surface will be lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate, let's consider you are flying at 3000 ft or roughly 900 mb.  Everywhere on this pressure surface will indicate 3000 ft on our altimeter for its current setting.  If we go somewhere hot, this pressure surface rises, and so we climb (though we think we are level) with this pressure surface but because the pressure has not changed, we still indicate 3000 ft.  However, we are higher than 3000 ft in reality.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This follows into your next question.  Aneroid wafers detect pressure changes and your altimeter displays an altitude &lt;strong&gt;not&lt;/strong&gt; corrected for temperature.  This is why your true altitude can vary with temperature for a constant indicated altitude.  When you correct the altitude for temperature we call this &quot;density altitude&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So back to my example above, your are flying along at 900 mb and indicating 3000 ft, and heading into warmer air.  The pressure surface starts to gently rise and as it does you are not yet following that rise and your altimeter will indicate a descent.  In true level flight you will begin to fly into higher pressure in this case as the 900 mb surface rises above you and the aneroid wafer in your altimeter will indicate a lower altitude and a descent.  You correct this and climb back up to the 900 mb pressure level so that your altimeter will once again indicate 3000', all the while actually gently climbing on this pressure surface.  You won't really be cognizant of this while flying however, and will just minimize vertical speed and maintain altitude blissfully unaware that you are really flying on a sloping constant pressure surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To better illustrate this, consider the following figure:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lJp5d.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this figure the reds signify a warmer than average column of air and the blues a cooler then average column.  The whitish area in the middle is a column at average temperatures.  The black solid lines are isobars (lines of constant pressure).  The dashed black line is a true altitude above the surface. Finally, the bold black line is the pressure level that corresponds to the true altitude of the dashed line at ISA conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you should notice is that the pressure levels in the warm column are spaced further apart because the air is less dense and more of it is needed to produce the same pressure (as pressure is just the weight of all the air above it).  Likewise in the cool column the pressure levels are spaced closer together because the air is more dense than standard.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To tie this into the discussions above, consider yourself in the standard column (white background) at the true altitude above ground represented by the dashed line.  Your altimeter does not sense this true altitude but instead senses the pressure outside of the airplane.  This will be roughly calibrated to your true altitude (uncorrected for temperature) but using the local altimeter setting.  Now as you fly either to the left or to the right and maintain a constant indicated altitude, you will track along the bold line, as this is the pressure that corresponds to your true altitude at standard temps.  As you fly toward a colder column you will in reality descend, and you will climb as you fly into the warmer column. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-04-19T13:30:41.973" LastActivityDate="2014-04-19T13:30:41.973" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3015" PostTypeId="1" AcceptedAnswerId="3016" CreationDate="2014-04-03T03:29:25.850" Score="54" ViewCount="53096" Body="&lt;p&gt;One thing I've always wondered is: do airplanes have keys that you put in the ignition to start?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And on the outside doors? Otherwise how are they secured and started?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested to know about a broad range of aircraft; from GA, all the way to airliners.&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-12-19T21:01:48.040" Title="Do planes have keys?" Tags="&lt;cockpit&gt;&lt;security&gt;" AnswerCount="9" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3016" PostTypeId="2" ParentId="3015" CreationDate="2014-04-03T03:37:00.277" Score="45" Body="&lt;p&gt;Small planes tend to have keys, but not all.  The bigger the plane the less likely a key is needed and once you get into jets, I can't think of any that need keys for engine starts.  The starting and securing of engines with no keys comes down to switches and knobs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise with exterior doors, on smaller planes including private end executive jets, you can find keyed exterior doors and luggage compartments.  With transport jets at airlines you won't find keys. To secure those doors the jet bridge is pulled away from the airplane so there is no physical access to the boarding door. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-03T03:37:00.277" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="3017" PostTypeId="2" ParentId="2839" CreationDate="2014-04-03T05:29:26.053" Score="5" Body="&lt;p&gt;I have no study to refer to, but I expect the results to differ very much from group to group. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;em&gt;airline operations&lt;/em&gt;, I imagine the objective of the pilot is often to &lt;strong&gt;maintain a constant attitude&lt;/strong&gt;, varied with a &lt;strong&gt;smooth transition to another attitude&lt;/strong&gt;. This would be easy to achieve with the first option you describe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;em&gt;military operations&lt;/em&gt;, I think a &lt;strong&gt;rapid feedback&lt;/strong&gt; is desired. This aligns better with the seconds option you describe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you would perform a study under pilots, the response you'll get will very likely be that they prefer whatever they are used to at the moment. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="247" LastEditDate="2014-04-05T14:22:44.993" LastActivityDate="2014-04-05T14:22:44.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3018" PostTypeId="1" AcceptedAnswerId="3019" CreationDate="2014-04-03T05:48:12.720" Score="6" ViewCount="853" Body="&lt;p&gt;How does the Earth's eastward motion figure into the tracks proposed by Inmarsat data etc?&lt;/p&gt;&#xA;" OwnerUserId="1991" LastEditorUserId="22550" LastEditDate="2018-11-22T15:00:01.193" LastActivityDate="2018-11-22T15:00:01.193" Title="MH370 Curved Track / Arc to southwest...Isn't this also affected by the Earth's motion?" Tags="&lt;navigation&gt;&lt;mh370-incident&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ClosedDate="2018-11-22T15:09:32.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="3019" PostTypeId="2" ParentId="3018" CreationDate="2014-04-03T05:53:08.300" Score="9" Body="&lt;p&gt;Not significantly. The aircraft flies in the air. The air moves over the earth and takes the plane with it. Of course wind is affected by the rotation of the earth, but there is little direct effect of Earth's rotation on the motion of the plane. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Coriolis_effect&quot;&gt;coriolis forces&lt;/a&gt; have a negligible effect on the aircraft's track.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Inmarsat satellite used is geostationary, so it rotates as fast around the earth as the earth around its axis. The nett effect is zero. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-03T05:53:08.300" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3020" PostTypeId="2" ParentId="3015" CreationDate="2014-04-03T06:41:38.427" Score="11" Body="&lt;p&gt;C-160 TRANSALL has a door lock. As a military cargo aircraft sometimes lands at remote airfields (or not even airfields), this is needed to &quot;secure&quot; the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="84" LastActivityDate="2014-04-03T06:41:38.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3021" PostTypeId="1" AcceptedAnswerId="3023" CreationDate="2014-04-03T07:58:58.400" Score="10" ViewCount="5712" Body="&lt;p&gt;On planes that have a captain and a first officer, how are flight hours logged and split between the two?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the hours split between the Capt and First Officer based on who is physically piloting the plane or are the same amount of hours are assigned to both? &lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-02-18T20:00:41.133" LastActivityDate="2015-02-18T20:22:04.690" Title="Do the captain and first officer log the same hours for a flight?" Tags="&lt;logging&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3022" PostTypeId="2" ParentId="2980" CreationDate="2014-04-03T08:07:33.533" Score="2" Body="&lt;p&gt;I think it also depends on kind of aircraft you are flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In jet aircraft speed is always controlled with power, lowering the nose to try and gain some speed on short final would destabilise the aircraft and probably lead to a more &quot;firm&quot; arrival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft with underslung engines require forward pressure when applying power, which is quite noticeable on approach, due to pitch-power couple. The reverse is also true, take power off and you will need to trim back.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-04-03T08:07:33.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3023" PostTypeId="2" ParentId="3021" CreationDate="2014-04-03T08:07:48.250" Score="8" Body="&lt;p&gt;Both log time, they just log it as different things. This is similar as a student and instructor logging time, but for different roles. The captain is the pilot-in-command and thus logs 'PIC', the F/O is second-in-command and logs 'SIC'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot who is tasked with controlling the plane is called 'PF' or &quot;pilot flying&quot;, and the other is called 'PNF' or &quot;pilot not flying&quot;, or &quot;pilot monitoring&quot;. This doesn't affect who's PIC and who's SIC though, and if I understand correctly, it's not generally logged who's actually flying.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="65" LastEditDate="2015-02-18T20:22:04.690" LastActivityDate="2015-02-18T20:22:04.690" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3024" PostTypeId="2" ParentId="3021" CreationDate="2014-04-03T08:36:40.960" Score="3" Body="&lt;p&gt;This is well covered by the &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/61.55&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.55&lt;/a&gt; aspect of this discussion: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1017/does-a-second-in-command-have-to-be-landing-and-instrument-current-like-a-pilot&quot;&gt;Does a Second In Command have to be landing and instrument current like a Pilot In Command does?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but a basic important detail is that an SIC has to be required for the operation and you have to be qualified to act as such in order for you to log SIC time.&lt;/p&gt;&#xA;" OwnerUserId="1977" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-18T20:18:36.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3025" PostTypeId="2" ParentId="3018" CreationDate="2014-04-03T08:55:12.560" Score="5" Body="&lt;p&gt;The problem with this question is that there is a seriously wrong assumption behind: you are assuming that the airplane &lt;em&gt;drifts&lt;/em&gt; along a course, like a curling stone after being launched, and is affected by all kind of environmental disturbances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing is that the airplane has engines and control surfaces, in the case in question even an autopilot: if a certain course/track is selected, the plane will follow it, eventual wind will simply change the attitude at which the plane is flying (yaw for side component, pitch for front component), not the ground track. Unless you are in sidewinds/headwinds that exceed the top airspeed of the aircraft, but that was not likely the case.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-04-03T08:55:12.560" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3026" PostTypeId="2" ParentId="3018" CreationDate="2014-04-03T10:00:44.350" Score="5" Body="&lt;p&gt;The earth's rotation affects aircraft in much the same way as it affects you and I on the surface. From that perspective we are all being carried along at around 1000 MPH. Since the atmosphere is a very very very thin layer of gas above the surface, it pretty much rotates with the surface. You'll notice the oceans don't slosh across the continents every 24 hours too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Federico pointed out, following a constant magnetic heading from a fixed point on the surface will not be affected by the speed of rotation of the planet. Your navigational frame of reference is earth-centric not solar-centric (say).&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-04-03T10:08:57.793" LastActivityDate="2014-04-03T10:08:57.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3027" PostTypeId="2" ParentId="3015" CreationDate="2014-04-03T11:29:18.470" Score="20" Body="&lt;p&gt;Private aircraft tend to be parked at airports with no effective security, and owned by individuals who expect to start and lock it like a car. I've seen many, and they all had ignition keys. Small aircraft (mainly single-engine) are also more-or-less interchangeable - if you can fly a Cessna you can fly a Beechcraft without any real issues so theft is a genuine concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial aircraft are typically parked at large airports with 24-hour security, these days likely armed. And they are not interchangeable. Put a 747 captain with 20 years experience in Boeings into an Airbus 320 and he won't be able to find the light switch, never mind fly it away.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-04-03T11:29:18.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3028" PostTypeId="2" ParentId="3021" CreationDate="2014-04-03T12:08:53.027" Score="6" Body="&lt;p&gt;To expand on the previous answers (and offer a small correction), CFR 14 part 61.65 states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A sport, recreational, private, commercial, or airline transport&#xA;  pilot may log pilot in command flight time for flights-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) &lt;strong&gt;When the pilot is the sole manipulator of the controls of an&#xA;  aircraft for&#xA;      which the pilot is rated&lt;/strong&gt;, or has sport pilot privileges for that category and&#xA;      class of aircraft, if the aircraft class rating is appropriate;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This has been interpreted by the FAA on several occasions as to mean that an SIC can log the time as a PIC when he is the one flying the aircraft. You can look for 'Legal Interpretation # 92-46' where this very same issue is addressed (they even specifically state that both the PIC and SIC can log PIC time in such cases).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, as others have already mentioned, an SIC can log SIC time when he is a PNF and is performing the duties of an SIC (provided the type or operational certificate requires a two person crew).&lt;/p&gt;&#xA;" OwnerUserId="1343" LastEditorUserId="72" LastEditDate="2014-04-09T03:50:02.153" LastActivityDate="2014-04-09T03:50:02.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3029" PostTypeId="2" ParentId="2994" CreationDate="2014-04-03T14:32:08.593" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What should a pilot do?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Follow the checklist?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is there any checklist?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are many such checklists in the intertubes and whole books have been written on the subject&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;p&gt;Here's the start of one for &lt;a href=&quot;http://www.737ng.co.uk/B737-700%20Quick%20Reference%20Handbook%20(QRH).pdf&quot; rel=&quot;noreferrer&quot;&gt;737s&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xQwKh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison, here's one for a &lt;a href=&quot;http://www.puc.edu/__data/assets/pdf_file/0004/9058/C152Checklist.pdf&quot; rel=&quot;noreferrer&quot;&gt;Cessna light aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/T93KW.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Are commercial jets buoyant?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, initially, if substantially in once piece. We know that because several intrepid pilots have tested this idea &lt;em&gt;(obligatory hat-tip to &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;Sullenberger&lt;/a&gt;)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes sense that the fuel tanks in the wings, especially once emptied of fuel, are buoyant. The wings are obviously capable of supporting the fuselage. The fuselage is a pressurised tube and should be buoyant too, until the passengers and crew start making large holes in it.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-04-03T15:35:57.127" LastActivityDate="2014-04-03T15:35:57.127" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3030" PostTypeId="2" ParentId="2977" CreationDate="2014-04-03T15:52:32.583" Score="-2" Body="&lt;p&gt;If approaching an uncontrolled field at altitude a pilot can over fly the airport in order to determine wind direction and traffic in the pattern. The pilot can then begin circling while descending to pattern altitude and enter the pattern merging with other traffic. General aviation airports are not usually located where there are obstacles that have to be avoided during the approach unless there are mountains nearby that prevent a straight in final approach. &lt;/p&gt;&#xA;" OwnerUserId="1998" LastActivityDate="2014-04-03T15:52:32.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3031" PostTypeId="1" AcceptedAnswerId="3034" CreationDate="2014-04-03T16:21:28.053" Score="3" ViewCount="641" Body="&lt;p&gt;Pilots flying VFR follow clearances like the &quot;mall visual&quot; or &quot;east channel departure.&quot; These are based on features of the local area that are easy to identify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are procedures like this official? Where could a reference be found for these procedures?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="19" LastEditDate="2017-01-20T08:54:11.080" LastActivityDate="2017-01-20T13:34:06.100" Title="Are approach and departure procedures based on visual reference points official VFR procedures?" Tags="&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3032" PostTypeId="2" ParentId="2977" CreationDate="2014-04-03T16:25:10.943" Score="3" Body="&lt;p&gt;I've done quite a number of circling approaches at non-towered airports.  ATC clears one for the approach by type (VOR 4, VOR-A, GPS 32, etc).  There's no mention of how it is executed or terminates (other than missed approach instructions).  Want to fly the RNAV/GPS by the LNAV minimums, fine.  LPV, sure, go ahead, want to circle from 32 around to 4, they don't know how you're doing it.  They just know that the airspace around the airport is clear for you to execute and approach (and go missed).  Once you switch to CTAF, you're otherwise on your own.  There's nobody to give you a landing clearance either, but that doesn't mean you're not allowed to land!  :-)&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-04-03T16:25:10.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3033" PostTypeId="2" ParentId="3015" CreationDate="2014-04-03T16:29:15.453" Score="5" Body="&lt;p&gt;I can only speak to types I have experience with, so:  Light GA singles typically have ignition keys.  Light GA twins typically do not.  When you get to the heavy stuff, I have no idea.  :-)&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-04-03T16:29:15.453" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3034" PostTypeId="2" ParentId="3031" CreationDate="2014-04-03T17:09:40.513" Score="11" Body="&lt;p&gt;Yes, they are official, this is the &lt;a href=&quot;https://skyvector.com/files/tpp/1701/pdf/00582MALL_VIS34RCL.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;KSEA MALL VISUAL RWY 34R/C/L&lt;/a&gt; approach plate:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LcTLR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LcTLR.png&quot; alt=&quot;KSEA MALL VISUAL RWY 34R/C/L&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find a &quot;East Channel Departure&quot; but if you know what airport it belongs to, you can find it in the Terminal Procedures publication, either in paper form or &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/&quot; rel=&quot;nofollow noreferrer&quot;&gt;online&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not VFR procedures, but rather visual IFR procedures. The MALL VISUAL would not be assigned to a VFR flight. Some airports do have special arrival/departure procedures which apply to VFR flights; these can be found in the Airport/Facilities Directory (A/FD) or on a website like &lt;a href=&quot;http://www.airnav.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airnav.com/&lt;/a&gt; (for the US anyway).&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="62" LastEditDate="2017-01-20T13:34:06.100" LastActivityDate="2017-01-20T13:34:06.100" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3035" PostTypeId="2" ParentId="3011" CreationDate="2014-04-03T21:52:59.537" Score="4" Body="&lt;p&gt;Pressure, density and temperature are related (approximately) through the ideal gas equation. In the general form it is&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$PV=nRT$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $P$ is pressure, $V$ is volume, $n$ is amount, $T$ is temperature and $R$ is ideal gas constant. If you have an &lt;em&gt;enclosed&lt;/em&gt; container filled with air, volume ($V$) and amount ($n$) are the same, so pressure increases proportionally to temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In free atmosphere, however, the &lt;em&gt;pressure&lt;/em&gt; is determined by the weight of the air above and thus &lt;em&gt;mostly fixed&lt;/em&gt;, so by heating the air it increases volume instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get to density, we divide the equation by volume and arrive at:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$P=\rho RT$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $\rho$ is the density (and handwave the switch from amount to mass, hiding the gas-specific conversion factor in the gas constant). The outside pressure is constant, so the density actually &lt;em&gt;decreases&lt;/em&gt; as temperature increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practical effect of this is that since engine power depends on amount of air it can draw in the fixed volume of the cylinders performance is worse when it's warmer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it remains to be explained what governs the open air pressure. The pressure at any given point is caused by the weight of the air above it. Because from the above at constant temperature the density is proportional to pressure, the full equation is differential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\Delta P \sim \rho\Delta h$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In words the change of pressure is equal to difference in height times density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure at ground level is affected by weather systems in complex ways. But since colder air is denser, it means that when it's cold the pressure will decrease faster with altitude than when it's hot. Now the altimeter really measures pressure and it only has adjustment for sea-level pressure, but not for temperature. So when you set your altimeter on the ground and climb 1000 feet, you'll be more than 1000 feet above ground when it's hot because the pressure decreases slowly and &lt;em&gt;less than 1000 feet above ground when it's cold&lt;/em&gt;. Some procedures even &lt;a href=&quot;https://aviation.stackexchange.com/a/2261/524&quot;&gt;have minimal temperature&lt;/a&gt; because of this.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-09-02T04:58:45.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3037" PostTypeId="1" CreationDate="2014-04-04T03:26:23.937" Score="9" ViewCount="2167" Body="&lt;p&gt;On SIGWX charts, it shows pairs of symbols with, say, &lt;code&gt;*/**&lt;/code&gt; or &lt;code&gt;**/**&lt;/code&gt;. I know what the symbols mean on either side, but why are there two, and what does the slash indicate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would love good resources that explain more, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example chart here, from &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_questions/media/sport_rec_private_akts.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA sample questions&lt;/a&gt; (caution: 37 MB download), Figure 20, over Southern California.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I’m also interested in knowing what a dot with &lt;code&gt;R&lt;/code&gt; underneath means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hLi3R.png&quot; alt=&quot;Example chart&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="167" LastEditDate="2014-05-14T01:57:19.420" LastActivityDate="2017-03-19T02:13:18.093" Title="On SIGWX (significant weather) charts, what does **/** mean?" Tags="&lt;weather&gt;&lt;aeronautical-charts&gt;&lt;symbology&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3038" PostTypeId="2" ParentId="3037" CreationDate="2014-04-04T03:29:40.043" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://www.beyourowncaptain.com/downloads/files/Reading%20Prog%20Charts.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://www.beyourowncaptain.com/downloads/files/Reading%20Prog%20Charts.pdf&lt;/a&gt;&#xA;&lt;a href=&quot;http://aviationweather.gov/static/adds/docs/metars/wxSymbols_anno1.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://aviationweather.gov/static/adds/docs/metars/wxSymbols_anno1.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Asterisks are snow, dots are rain. The slash means a mixture of the two. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Icv7k.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dot with an R under it is a substitution for the the thunderstorm symbol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2qb7a.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you're looking at isn't a &lt;em&gt;real&lt;/em&gt; SIGWX chart, it's a testing figure.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastEditorUserId="1900" LastEditDate="2014-04-04T03:46:04.763" LastActivityDate="2014-04-04T03:46:04.763" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3039" PostTypeId="1" AcceptedAnswerId="3043" CreationDate="2014-04-04T04:10:10.767" Score="40" ViewCount="22609" Body="&lt;p&gt;Is a private pilot license holder in the USA who is giving a scenic tour with friends allowed to let them fly the plane? Are there any restrictions on when this can be done?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my mind, this could be done safely while at altitude and the pilot could let them do a few shallow turns.  They wouldn't want them doing anything complex and would want them to instantly let go if asked.&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="69" LastEditDate="2014-04-08T01:33:00.793" LastActivityDate="2019-12-19T18:22:59.477" Title="Are pilots allowed to let passengers fly the plane?" Tags="&lt;faa-regulations&gt;&lt;passenger&gt;&lt;ppl&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3040" PostTypeId="1" AcceptedAnswerId="3044" CreationDate="2014-04-04T04:31:36.943" Score="21" ViewCount="16555" Body="&lt;p&gt;I've heard of level A, B, C, and D simulators, (as well as FTD and AATDs) but know nothing about them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What criteria is used to certify a sim as a particular level?&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="72" LastEditDate="2014-04-05T15:57:26.820" LastActivityDate="2018-04-03T22:34:53.257" Title="What are the differences between various simulator levels?" Tags="&lt;flight-simulator&gt;&lt;terminology&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3041" PostTypeId="5" CreationDate="2014-04-04T04:52:00.470" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-04T04:52:00.470" LastActivityDate="2014-04-04T04:52:00.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3042" PostTypeId="4" CreationDate="2014-04-04T04:52:00.470" Score="0" Body="The ratio of the forward distance traveled to the vertical distance an aircraft descends when gliding without any power." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-04-04T05:10:46.093" LastActivityDate="2014-04-04T05:10:46.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3043" PostTypeId="2" ParentId="3039" CreationDate="2014-04-04T05:09:39.693" Score="34" Body="&lt;p&gt;For a non-commercial flight under Part 91 rules there are no issues I'm aware of with letting a non-rated passenger handle the controls - and it's done quite frequently (I can't think of any pilots I know offhand who &lt;em&gt;haven't&lt;/em&gt; had someone else take the controls for one reason or another).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rated pilot is still pilot-in-command of the flight and ultimately responsible for everything that happens, so they need to be relatively certain their friend will let go of the controls if told to do so, and they need to maintain situational awareness (traffic scan, airspace, etc. -- if the friend blunders into Class B airspace it's going to land in the pilot's lap) and be ready to take over if the friend starts doing something that could jeopardize the safety of the flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are some common-sense limits here: something insane like have two non-rated friends at the controls the rated pilot being PIC from the back seat giving them instructions over the intercom would be a no-go.&lt;br&gt;&#xA;Similarly while this sort of thing is a total non-event in an aircraft with typical dual controls you would probably want to have a higher level of trust in your friend if you're flying something with a throw-over yoke.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-04T05:09:39.693" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3044" PostTypeId="2" ParentId="3040" CreationDate="2014-04-04T09:09:08.077" Score="20" Body="&lt;p&gt;&lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/5b7322950dd10f6b862569ba006f60aa/$FILE/Appx1.pdf&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; there is a nice tabular representation of the requirements for each level.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_simulator#Flight_simulator_.22levels.22_and_other_categories&quot; rel=&quot;noreferrer&quot;&gt;Wiki&lt;/a&gt; provides a handy summary:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Full Flight Simulators (FFS)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;FAA FFS Level A&lt;/strong&gt; - A motion system is required with at least three degrees of freedom. Airplanes only.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;FAA FFS Level B&lt;/strong&gt; - Requires three axis motion and a higher-fidelity aerodynamic model than does Level A. The lowest level of helicopter flight simulator.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;FAA FFS Level C&lt;/strong&gt; - Requires a motion platform with all six degrees of freedom. Also lower transport delay (latency) over levels A &amp;amp; B. The visual system must have an outside-world horizontal field of view of at least 75 degrees for each pilot.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;FAA FFS Level D&lt;/strong&gt; - The highest level of FFS qualification currently available. Requirements are for Level C with additions. The motion platform must have all six degrees of freedom, and the visual system must have an outside-world horizontal field of view of at least 150 degrees, with a Collimated (distant focus) display. Realistic sounds in the cockpit are required, as well as a number of special motion and visual effects.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-04T09:09:08.077" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3045" PostTypeId="2" ParentId="2999" CreationDate="2014-04-04T11:20:22.553" Score="7" Body="&lt;p&gt;Glide distance does indeed depend heavily on the airplane's characteristic glide ratio, which depends on airspeed, as the answers above describe.  However, the answers above assume still air, and real air is never still.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you glide with a steady tailwind, you'll glide further than you will in still air; a steady headwind will cut your glide.  (You'll get the same sink rate and therefore the same time aloft, but you'll make a different amount of distance over the ground.)  If you're at altitude, it can be difficult to tell which way the wind is blowing unless you already know or unless you have a GPS so that you (or it, automatically) can compare your speed across the ground with your speed through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, downdrafts will cut your altitude and thereby your glide distance; but updrafts will do the opposite.  As a matter of fact, in the right kind of weather pilots who are trained to find updrafts--glider pilots, for example--can stay aloft without power for as long as they like.  Updrafts are in general powered by the sun, though, so after dark it gets difficult to find &quot;the right kind of weather.&quot;  Also, updrafts tend to be localized and fairly stationary, so flying circles to stay in one, if it's weaker than you expected, may use up more of your gliding time than it adds and so reduce the total distance over the ground that you can glide.&lt;/p&gt;&#xA;" OwnerUserId="2012" LastActivityDate="2014-04-04T11:20:22.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3047" PostTypeId="2" ParentId="3015" CreationDate="2014-04-04T11:35:09.230" Score="22" Body="&lt;p&gt;As a private pilot, single-engine land, I've flown maybe fifty different light planes--none with any more than four seats or 210HP--and all of them have had ignition keys.  I haven't been in the cockpit of anything bigger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally the keys have five positions: OFF, MAG 1, MAG 2, BOTH, and START.  You insert the key at the OFF position, turn it all the way to START and hold it there until the engine catches, and then release it back to BOTH.  MAG 1 and MAG 2 (sometimes LEFT and RIGHT) are for the runup check just before takeoff to make sure both your magnetos are working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually the same key that fits in the ignition switch fits in the door lock.  It's pretty common for a small plane to have only one door that's unlockable from the outside: you lock all the other doors from the inside, then climb out and lock the last door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing I've noticed, though, is that keys and locks for small planes don't appear to be serious--at least, not the same level of serious that you see on cars and buildings.  They're more serious than briefcase keys or computer-case keys, but they look about as pickable as a cheap padlock...and while I've never looked, I wouldn't be surprised if you could reach under the edge of the instrument panel, pull wires with spade lugs off the back of the ignition switch, and touch them together yourself.&lt;/p&gt;&#xA;" OwnerUserId="2012" LastActivityDate="2014-04-04T11:35:09.230" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3048" PostTypeId="2" ParentId="2999" CreationDate="2014-04-04T12:59:11.137" Score="11" Body="&lt;p&gt;To give some concrete examples: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Cessna 172 might fly at 2000 ft for a short hop, or at 12500 ft for a longer cross-country flight. My rule of thumb is about 1.5 nautical miles glide per 1000 ft altitude above ground level, thus:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From 2000 ft, a Cessna would be able to glide about 3 nautical miles (3.5 statute miles, 5.5 km), and it would take about 3 minutes for that. &lt;/li&gt;&#xA;&lt;li&gt;From 12500 ft, just in proportion, it would be about 18 nautical miles (21 statute miles, 33 km), giving the pilot an ample 18 minutes to troubleshoot, find a suitable landing spot, and communicate the predicament.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A big jet flies higher during cruise, say at 38000 ft, and has a better glide ratio.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From 38000 ft, a jet might glide for 75 to 100 nautical miles (140 to 180 km), and take about 20 minutes to do so.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1984" LastActivityDate="2014-04-04T12:59:11.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3049" PostTypeId="1" AcceptedAnswerId="3053" CreationDate="2014-04-04T15:24:05.263" Score="30" ViewCount="34716" Body="&lt;p&gt;In order to help ATC identify an aircraft on their screen, they may ask the aircraft to &quot;ident.&quot; The pilot presses a button on their transponder, and the controller can verify that the aircraft they are talking to is the one they are looking at on the screen.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In what situations does ATC ask for ident, and is it ever required by procedure?&lt;/li&gt;&#xA;&lt;li&gt;What does the transponder actually do in this mode?&lt;/li&gt;&#xA;&lt;li&gt;What does the controller see on their screen?&lt;/li&gt;&#xA;&lt;li&gt;Does it depend at all on either the code or the mode the transponder is currently set for?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2016-05-25T14:45:36.033" Title="How does IDENT work?" Tags="&lt;air-traffic-control&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3050" PostTypeId="1" AcceptedAnswerId="3051" CreationDate="2014-04-04T15:28:00.773" Score="14" ViewCount="57478" Body="&lt;p&gt;I have recently been using a mobile app to track flights, which is really cool.  I live in the rural heartland of America, so it's an event for me to see an A380 actually flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every once in a while, a squawk 7700 alert will come up, which I understand is the emergency transponder code. There are more, such as 7600 and 7500, which I find are less common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, is there a way to do some post-mortem followup as to why the aircraft squawked the code?  Is this public information that can be found by some agency such as the NTSB?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastEditorUserId="65" LastEditDate="2015-03-11T20:43:08.773" LastActivityDate="2015-07-12T20:05:16.390" Title="Can I find out why an aircraft squawked an emergency code (7x00)?" Tags="&lt;emergency&gt;&lt;transponder&gt;&lt;ntsb&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3051" PostTypeId="2" ParentId="3050" CreationDate="2014-04-04T15:39:35.130" Score="14" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0502.html&quot;&gt;This FAA webpage&lt;/a&gt; has a list of the various transponder codes and what they are used for, which will give you an idea of what the problem is.  Unless there is an actual aircraft incident or accident which requires the FAA to investigate though, you won't be able to find a record of it.  In fact, pilots aren't even required to file a report unless requested, and those don't go into a public database.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For actual incidents or accidents, you can look at the NTSB &lt;a href=&quot;http://www.ntsb.gov/aviationquery/index.aspx&quot;&gt;Accident Database &amp;amp; Synopses&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For pilot reports to the NASA ASRS self-reporting safety system, you can &lt;a href=&quot;http://asrs.arc.nasa.gov/search/database.html&quot;&gt;search their database&lt;/a&gt;.  If the pilot filed a report then you will see it show up there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commonly used emergency codes are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;7500 - Hijack Code&lt;/li&gt;&#xA;&lt;li&gt;7600 - Loss of Radio Communications Code&lt;/li&gt;&#xA;&lt;li&gt;7700 - Emergency Code&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, some countries use the code 7000 for VFR traffic (which is not an emergency code), but the US uses 1200 instead.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-04T20:02:13.570" LastActivityDate="2014-04-04T20:02:13.570" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3052" PostTypeId="1" AcceptedAnswerId="3061" CreationDate="2014-04-04T15:58:20.000" Score="27" ViewCount="70762" Body="&lt;p&gt;I have been using an Android app to track flights. Their information is pulled from their own proprietary database, and some (with 5 minute delay) from the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was thinking about making an app that would do this as well by pulling from multiple data sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some good APIs, either paid or free, that gives you near realtime data of flying aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastEditorUserId="1467" LastEditDate="2016-04-26T11:31:16.103" LastActivityDate="2018-06-09T05:47:04.540" Title="Is there an API to get real-time FAA flight data?" Tags="&lt;faa&gt;&lt;online-tracking&gt;&lt;website&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="23" ContentLicense="CC BY-SA 3.0" />
  <row Id="3053" PostTypeId="2" ParentId="3049" CreationDate="2014-04-04T16:45:18.903" Score="29" Body="&lt;p&gt;(Note: This answer is tailored to the U.S. / FAA, because that is what I'm familiar with. All the citations and references are FAA materials. If anyone has any tips on possible international differences, please let me know and I'll edit them in. That said, I believe the &lt;em&gt;descriptions&lt;/em&gt; I give are fairly consistent across the world, even if the FAA reg citations don't directly apply.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;In what situations does ATC ask for ident, and is it ever required by procedure?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally, &quot;ident&quot; is used to help a controller identify an aircraft's secondary radar (transponder) return. By asking the pilot to &quot;squawk ident,&quot; the controller can ensure that the aircraft he/she is talking to matches the radar target he thinks is that aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can also be used for communication, to allow a pilot to respond if their radio transmitter has failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is a method to allow a controller to identify an aircraft on radar, per section 5-3-3 of &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.current/documentNumber/7110.65&quot;&gt;FAA Order 7110.65 (pdf)&lt;/a&gt;:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When using only Mode 3/A radar beacon to identify a target, use one of the following methods:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Request the aircraft to activate the &quot;IDENT&quot; feature of the transponder and then observe the identification display.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For lost communication, per section 10-4-4 of &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.current/documentNumber/7110.65&quot;&gt;7110.65&lt;/a&gt;:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Take the following actions, as appropriate, if two-way radio communications are lost with an aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;c.&lt;/strong&gt; Attempt to re-establish communication by having the aircraft use its transponder or make turns to acknowledge clearances and answer questions. Request any of the following in using the transponder:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; Request the aircraft to reply Mode 3/A “IDENT.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This last scenario is common when experiencing radio failures. If ATC suspects that you might be able to &lt;em&gt;hear&lt;/em&gt; them but not to talk back, they might say something like &quot;Cessna 12345, if you can hear me, squawk ident.&quot; If you reply by pressing the IDENT button, they can then issue you further instructions and ask you to acknowledge those instructions by pressing IDENT again.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What does the transponder actually do in this mode?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In normal operation, every time the transponder receives an &lt;em&gt;interrogation&lt;/em&gt; from a ground station, it replies with a data block containing certain pieces of information. &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_%28aviation%29#Ident&quot;&gt;This data block contains&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The encoded pressure altitude (for Mode C transponders)&lt;/li&gt;&#xA;&lt;li&gt;A 12-bit identification code (this is the 4-digit code you select in the cockpit)&lt;/li&gt;&#xA;&lt;li&gt;A single extra bit for the &quot;ident&quot; flag&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When you push the IDENT button in the cockpit, the transponder sets that extra &quot;ident&quot; bit in its reply data. Anytime the transponder is interrogated while IDENT is active (for a set duration of time after you press the button in the cockpit), its reply data block will have the IDENT bit set. ATC computer systems notice this and cause the IDENT to be shown on the controller's radar display.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What does the controller see on their screen?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It depends on the type of radar system in use. Generally the radar target will either blink, its symbol will change (or &quot;blossom&quot;), or an indication such as &quot;ID&quot; will blink in the aircraft's data block (where the callsign is shown).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AIM has some schematic pictures that show what an IDENT looks like on an ARTS-III scope (an older system still in use at some TRACONs). See &lt;a href=&quot;http://www.faraim.org/aim/aim-4-03-14-229.html&quot;&gt;Figures 4-5-2&lt;/a&gt; and &lt;a href=&quot;http://www.faraim.org/aim/aim-4-03-14-231.html&quot;&gt;4-5-3&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will try to find some pictures of other radar systems such as those used at ARTCCs and newer TRACONs.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Does it depend at all on either the code or the mode the transponder is currently set for?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The code doesn't matter. The IDENT flag is an extra bit in the transponder's reply data that's independent of the 12 bits used for the code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the IDENT will only be observed if the transponder is operating (not OFF or in a STANDBY mode). But the IDENT works in any mode used by normal civilian transponders (Modes A, C or S).&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="755" LastEditDate="2016-05-25T14:45:36.033" LastActivityDate="2016-05-25T14:45:36.033" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3054" PostTypeId="2" ParentId="3049" CreationDate="2014-04-04T16:45:55.943" Score="1" Body="&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_%28aviation%29#Ident&quot; rel=&quot;nofollow&quot;&gt;wikipedia&lt;/a&gt; (&lt;em&gt;emphasis mine&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All mode A, C, and S transponders include an &quot;IDENT&quot; button, which &lt;strong&gt;activates a special thirteenth bit on the mode A reply known as IDENT&lt;/strong&gt;, short for &quot;identify&quot;&quot;. When ground-based radar equipment receives the IDENT bit, it results in the aircraft's blip &quot;blossoming&quot; on the radar scope. This is often used by the controller to locate the aircraft amongst others by requesting the ident function from the pilot, e.g., &quot;Cessna 123AB, squawk 0363 and ident&quot;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In my limited experience, the time I had to IDENT was in crowded traffic so the controller could identify me. How it was explained to me (and I can't find an exact description for blossoming) was that the blip on ATC's screen that is you will &quot;pulse&quot;, sending out concentric circles for a few seconds. It makes it very obvious which craft is sending out the IDENT. &lt;a href=&quot;http://www.avweb.com/news/avionics/183231-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; gives a brief, slightly different description:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When you push the IDENT button, it adds an extra pulse to your replies that causes your target on the controller's radar scope to change appearance. (It either &quot;blooms&quot; on an approach control radar screen, or has a flashing &quot;ID&quot; on a center radar screen.) Controllers sometimes use this to help find your target, or to make sure the target they think is you really is.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-04-04T16:45:55.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3056" PostTypeId="1" AcceptedAnswerId="3060" CreationDate="2014-04-04T17:06:30.353" Score="19" ViewCount="5815" Body="&lt;p&gt;You can find anecdotal mention of this phrase among pilots you may talk to as well as postings on various forums.  The idea conveyed is that telling a controller to &quot;mark the tape&quot; means they will make take some action to note the current time for the audio recording of his seat, which can then be referred back to by someone.  As many anecdotes you can find about this, you'll find just as many saying this phrase is essentially an old wives tale, and means absolutely nothing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given a situation with a controller that I'd like to bring to the attention of his superiors, or perhaps just with him over the phone, does using the phrase &quot;mark the tape&quot; do anything?  If it does nothing, what is the proper procedure I should use to review something with a controller or their supervisor (e.g. noting time and frequency, asking for a phone number)?  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-08-15T20:11:52.293" Title="What happens when I tell ATC to &quot;mark the tape&quot;?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3057" PostTypeId="1" AcceptedAnswerId="3059" CreationDate="2014-04-04T17:11:03.917" Score="13" ViewCount="3373" Body="&lt;p&gt;Is there a procedure in place to request a copy of the audio recording of a specific ATC position over a specific time interval?  How is the request made? What are the limitations of such a request? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purpose of this answer, consider that there would be a need for the audio from a controller, which may involve multiple frequencies as well as interphone communication with other controllers.  As such, internet resources that provide recordings of specific frequencies would not be adequate.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-04T17:52:49.167" Title="Can I get official recordings of ATC audio?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3058" PostTypeId="2" ParentId="3049" CreationDate="2014-04-04T17:38:50.390" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;In what situations does ATC ask for ident, and is it ever required by procedure?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ATC asks a pilot to IDENT for identification purposes. If used, it usually on first (secondary) radar contact. Identification can be done by other means as well, for example by identifying turns, correlation to reported position etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0503.html&quot; rel=&quot;nofollow&quot;&gt;FAA document&lt;/a&gt; for how radar identification can be done by means of IDENT or otherwise.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What does the transponder actually do in this mode?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The transponder will, for a duration of 18 seconds after IDENT is pressed, change its reply to radar interrogations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the interrogation is a Mode A or Mode C interrogation, an additional pulse is appended 4.35 microseconds after the last framing pulse of the standard Mode A/C reply. This is called the SPI (special purpose identification) pulse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the interrogation is a Mode S interrogation (Uplink Format 4,5, 20 or 21) and the transponder is a Mode S transponder, the Flight Status field in the reply will be set to indicate that Ident is pressed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the Mode S transponder is transmitting ADS-B as well, the Surveillance Status field in the position messages will be set to indicate that Ident is pressed. This is also done for 18 seconds after the IDENT button is pressed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What does the controller see on their screen?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The controller will see an indication that the aircraft is IDENTifiying. In what form the indication is presented depends on the ATC system. For example, the data block may be flashing, boxed, or (partly) highlighted. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does it depend at all on either the code or the mode the transponder is currently set for?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, IDENT is independent of the Mode A code (squawk code) set in the transponder.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-05-25T13:05:07.473" LastActivityDate="2016-05-25T13:05:07.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3059" PostTypeId="2" ParentId="3057" CreationDate="2014-04-04T17:52:49.167" Score="9" Body="&lt;p&gt;In the specific situation of a pilot who is the subject of an FAA investigation, the Pilot's Bill of Rights requires that air traffic data (which includes audio recordings) be provided to the pilot. They would be expected to make the request directly to the FAA. There is a &lt;a href=&quot;http://www.faa.gov/pilots/rights/&quot; rel=&quot;noreferrer&quot;&gt;procedure for this&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;To ensure that relevant air traffic data you are seeking from a government contractor are obtained, you should provide the following information:&lt;/p&gt;&#xA;&lt;p&gt;a. Your name and your airman certificate number;&lt;br/&gt;&#xA;b. other relevant information (aircraft heading, altitude, call sign, transponder code, etc.) that will help the contractor locate relevant data; &lt;br/&gt;&#xA;c. the name/location of the contractor facility that you believe has air traffic data;&lt;br/&gt;&#xA;d. the date and local time of day when such data relevant to the your flight operation were generated;&lt;br/&gt;&#xA;e. the name of the FAA inspector, investigator or other FAA official (e.g., an air traffic controller who advises you about a possible pilot deviation) who notified you that you are under investigation;&lt;br/&gt;&#xA;f. the airman's phone number or email&lt;br/&gt;&lt;/p&gt;&#xA;&lt;p&gt;The individual should provide that information to the FAA by email to the following address: AirmenDataRequest@faa.gov.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The instructions include a warning about timeliness:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Depending on the type of data, they will normally be stored from 5 to 45 days and then they are destroyed or discarded in the normal course of business&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I don't have any information about the general case, though I imagine it depends on the facility and their workload.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-04T17:52:49.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3060" PostTypeId="2" ParentId="3056" CreationDate="2014-04-04T18:25:14.453" Score="19" Body="&lt;p&gt;These days, with digital recording, it's likely that nothing special happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Mark the tape&quot; is a holdover from when ATC recordings were actually &lt;em&gt;on tapes&lt;/em&gt; - you could ask a controller to &quot;mark&quot; a tape to hold it and prevent it being recycled for another recording while your &lt;a href=&quot;https://aviation.stackexchange.com/questions/3057/can-i-get-official-recordings-of-atc-audio&quot;&gt;request for a copy of the tape&lt;/a&gt; is being processed. (Anecdotally I've been told some facilities had tape rotations as short as 15 days, and a FOIA request letter could easily take longer than that to make it to the facility).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today much (probably most) of what is said on the frequency is recorded digitally, direct to hard drives, and kept around &quot;essentially forever&quot; as one of our local controllers put it when this came up at a recent event.  Basically the virtual &quot;tapes&quot; stick around for as long as the facility's recording machine has disk space to store them, and since audio files aren't that big facilities can store recordings a &lt;em&gt;lot&lt;/em&gt; longer than they did in the days of tape.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All that's really needed to pull a record to review it with a controller/supervisor is the date, time, facility, and frequency (and your aircraft callsign would probably be helpful too) - e.g. &quot;April 4, 2014 - JFK Local Control for Runway 04R (119.1) - United 123 Heavy&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Mark the tape and give me a phone number&quot; survives as non-standard phraseology that lets the controller know that you will likely have a bone to pick with someone when you get on the ground and gives them the opportunity to tell their supervisor that an annoyed pilot will be calling the facility in the near future (and hopefully give the supervisor time to listen to the tape).&lt;br&gt;&#xA;The useful part is really getting the facility phone number so you know who to call when you land.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-04-04T18:25:14.453" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3061" PostTypeId="2" ParentId="3052" CreationDate="2014-04-04T19:18:26.270" Score="25" Body="&lt;p&gt;You can't get real-time data from the FAA without an &lt;em&gt;operational need&lt;/em&gt;, and organizations which do receive real-time data cannot legally re-distribute this data publicly, except to other organizations approved by the FAA. An operational need pretty much means you have to be a flight dispatcher for an airline or commercial operator, not just have an interest in tracking flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get some real-time data from your local area using an ADS-B receiver. See this  question for more information: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1510/atc-real-time-traffic-services&quot;&gt;Where can I find real-time flight tracking with the least amount of delay?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are okay with the five minute delay, then &lt;a href=&quot;http://flightaware.com/commercial/flightxml/&quot; rel=&quot;noreferrer&quot;&gt;flightaware has an API&lt;/a&gt; you might consider. The direct feed from the FAA is called &lt;a href=&quot;http://www.fly.faa.gov/ASDI/asdi.html&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Situation Display to Industry (ASDI)&lt;/a&gt; and I believe you can apply for the delayed feed, though I've never gone through the process, and the government's site is very sparse in information. I would suggest contacting them before attempting to apply if it's something you're interested in.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-04-04T19:18:26.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3063" PostTypeId="2" ParentId="751" CreationDate="2014-04-04T20:31:48.203" Score="38" Body="&lt;p&gt;My favourite entry in my logbook is 2013-08-02 KOSH-KORD 1.5 hrs – from Air Venture in Oshkosh straight into Chicago O'Hare, in a Cessna 172 :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A friend of mine and I have flown into SFO (with our instructor), and dropped of my friend, who then took a Lufthansa flight to Munich.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, having flown into SFO, ORD, and SAN (San Diego, the busiest single-runway airport in the US) in a Cessna 172, all VFR, here my observations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;obviously, prepare. I normally call the FBO, and maybe even the tower, just to get their input, and ask what would be a good time of the day.&lt;/li&gt;&#xA;&lt;li&gt;best to fly with a fellow pilot, to share the workload.&lt;/li&gt;&#xA;&lt;li&gt;have a taxi diagram at hand and familiarise yourself with it... navigation on the ground is harder than following the instructions in the air at some of these airports!&lt;/li&gt;&#xA;&lt;li&gt;be prepared to wait outside class B for quite a bit, until they can work you in (and, be prepared to go somewhere else if they can't).&lt;/li&gt;&#xA;&lt;li&gt;I like to think that they're the more likely to squeeze you in the more &quot;professional&quot; you are (radio calls, following their instructions quickly and precisely, etc.)&lt;/li&gt;&#xA;&lt;li&gt;be prepared to be handed off from one frequency to the other for quite a bit.&lt;/li&gt;&#xA;&lt;li&gt;out of courtesy, I try to go in pretty fast (fast for a C172, that is). The runways are long, so I've been on final with 120+ knots (and yes, that was a no-flap landing!)&lt;/li&gt;&#xA;&lt;li&gt;ask the FBO about how much fuel you have to buy to get fees waived, and keep in mind that it's most likely going to be rather expensive... on a related note, in my experience the FBOs encourage you to come in, but then, they have nothing to lose: if you show up, they'll sell you overpriced fuel and charge you some fees; if ATC turns you away, they don't really care. That's why I like to talk to someone on the ATC side as well, or flight instructors at nearby GA airports.&lt;/li&gt;&#xA;&lt;li&gt;review the radio sequence for departure, typically they want you to speak to Clearance Delivery before you talk to Ground&lt;/li&gt;&#xA;&lt;li&gt;in my limited experience, ATC has been fast and professional in their communication, yet super helpful and friendly.&lt;/li&gt;&#xA;&lt;li&gt;personally, I think it's super fun, and an awesome privilege, and I'm grateful that it is possible in the US. I've only done it rarely, and would not want to abuse this privilege - if every Cessna single engine out there attempted to land in a major hub daily, the privilege would be curtailed rather quickly, I imagine&lt;/li&gt;&#xA;&lt;li&gt;it's just great to hear Ground say to you, &quot;see the United 737 in front? Follow it until you see X-ray 3 on your left&quot;. Even better to hear Tower say &quot;Lufthansa 123 heavy, hold short of Runway 27 left, traffic on final&quot;, and hear a reply &quot;Hold short 27 left, traffic in sight (chuckling), Lufthansa 123&quot;, while you float over the numbers past a giant Lufthansa 747 :-)  &lt;img src=&quot;https://i.stack.imgur.com/HATwt.jpg&quot; alt=&quot;Short Final SFO 28&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/yrknI.jpg&quot; alt=&quot;Lufthansa 747 holding short SFO 28L&quot;&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1984" LastEditorUserId="1984" LastEditDate="2014-04-05T07:35:34.100" LastActivityDate="2014-04-05T07:35:34.100" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3064" PostTypeId="1" CreationDate="2014-04-04T20:49:18.000" Score="5" ViewCount="1228" Body="&lt;p&gt;Are there currently any ADs for Boing 777s which would indicate the potential for catastrophic electronic system failures that might explain MH370's transponder failure and other issues?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was the aircraft used for MH370 in compliance with all ADs?&lt;/p&gt;&#xA;" OwnerUserId="2026" LastEditorUserId="19" LastEditDate="2017-01-20T08:56:42.280" LastActivityDate="2019-11-15T18:53:52.237" Title="Are there any Airworthiness Directives for the Boeing 777 that might explain MH370's disappearance?" Tags="&lt;commercial-aviation&gt;&lt;mh370-incident&gt;&lt;airworthiness-directive&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ClosedDate="2019-11-25T14:00:07.777" ContentLicense="CC BY-SA 3.0" />
  <row Id="3065" PostTypeId="2" ParentId="2958" CreationDate="2014-04-04T21:18:33.043" Score="12" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pressing the &lt;strong&gt;heading hold button will assume the current heading&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pressing &lt;strong&gt;heading select will follow the course as selected in the display&lt;/strong&gt;; this can be set by pressing the rotary encoder. It is also visible on the heading bug.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9OGZh.jpg&quot; alt=&quot;autopilot&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 777 primary flight display will display &lt;strong&gt;&lt;code&gt;HDG SEL&lt;/code&gt;&lt;/strong&gt; and &lt;strong&gt;&lt;code&gt;HDG HLD&lt;/code&gt;&lt;/strong&gt; for each selection respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ALSM6.jpg&quot; alt=&quot;pfd&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="97" LastEditDate="2014-04-05T05:41:17.730" LastActivityDate="2014-04-05T05:41:17.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3066" PostTypeId="5" CreationDate="2014-04-04T21:20:07.263" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;NOTE:&lt;/strong&gt; This tag is related to a current event under investigation.&lt;br&gt;&#xA;  Factual information on this incident is still being uncovered. As such, very few questions specific to this incident have concrete answers. Speculative questions (&quot;What do you think happened?&quot;) may be placed on hold until such time as factual answers can be provided.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Malaysia Airlines Flight 370 (a Boeing 777-200ER, registration 9M-MRO) disappeared on March 8, 2014 during a flight from Kuala Lumpur International Airport to Beijing Capital International Airport.&lt;br&gt;&#xA;The aircraft is currently missing, and a search is ongoing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="97" LastEditDate="2015-04-02T01:38:05.977" LastActivityDate="2015-04-02T01:38:05.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3067" PostTypeId="4" CreationDate="2014-04-04T21:20:07.263" Score="0" Body="For questions about Malaysia Airlines Flight 370's disappearance. Please make your question as specific as possible; general questions inviting speculation about the cause or nature of the incident (&quot;What do you think happened?&quot;) may be placed on hold until factual information is available." OwnerUserId="64" LastEditorUserId="62" LastEditDate="2014-12-22T16:27:58.263" LastActivityDate="2014-12-22T16:27:58.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3068" PostTypeId="1" AcceptedAnswerId="3069" CreationDate="2014-04-04T23:34:45.253" Score="18" ViewCount="11067" Body="&lt;p&gt;Sometimes, when I'm flying on the airlines, I'll board an aircraft where the aisles seem incredibly cramped, where it's almost impossible to move past without bumping every seat. I can't imagine how much of a nuisance it'd be for people larger than me! I once saw an obese person a bit stuck between one of the aisles, blocking the way for others to move into the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then I thought about what would happen in an emergency. What if there were numerous large people on board, and there was a fire?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, are there any limits to how much the airlines can squeeze their planes' aisles?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2018-11-30T12:26:17.857" Title="Is there any limit on how narrow aisles can be?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;transport-category&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3069" PostTypeId="2" ParentId="3068" CreationDate="2014-04-05T00:22:53.547" Score="16" Body="&lt;p&gt;For a transport category airplane with 20 or more seats the minimum aisle width is 15 inches from the floor to a height of 25 inches, and 20 inches width above a height of 25 inches.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§25.815&lt;br&gt;&#xA;  Width of aisle.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The passenger aisle width at any point between seats must equal or exceed the values in the following table:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ddJ0q.png&quot; alt=&quot;Aisle width table&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;A narrower width not less than 9 inches may be approved when substantiated by tests found necessary by the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="15954" LastEditDate="2018-11-30T12:26:17.857" LastActivityDate="2018-11-30T12:26:17.857" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3070" PostTypeId="1" CreationDate="2014-04-05T02:53:01.710" Score="20" ViewCount="2548" Body="&lt;p&gt;The airlines are always trying to jam more passengers into each plane. I'm smaller than today's average, and I'm still often uncomfortable in a standard Economy seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It occurred to me that in the current design, there's a great deal of space wasted over the passengers' heads. And that many of us passengers already do our best to sleep through flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence my question: Is there any reason an airline couldn't introduce a cabin in which some or all passengers travel in a reclining, rather than sitting, position? Seems to me that  it would be more comfortable (except for claustrophobes and those who really need to work during the flight). The enclosed space would inherently reduce some of the risks of passengers being thrown around in turbulence or an emergency landing; safety belts (or cargo restraint webbing? I'm not sure I'm joking) could handle the remaining risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, I don't really think it would be commercially viable ... but I'm wondering whether folks who actually Know Something about aircraft safety and loading think it's &lt;em&gt;technically&lt;/em&gt; viable.&lt;/p&gt;&#xA;" OwnerUserId="312" LastEditorUserId="97" LastEditDate="2014-04-05T06:13:30.853" LastActivityDate="2015-10-06T22:04:51.003" Title="Is it technically viable to reintroduce sleeping berths?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;airliner&gt;&lt;commercial-aviation&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3072" PostTypeId="2" ParentId="3070" CreationDate="2014-04-05T06:06:46.393" Score="15" Body="&lt;p&gt;Some airlines already offer sleeping facilities, by taking advantage of the A380's tremendous size:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/829ln.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A double-bed suite on Singapore Airlines&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qoGHy.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A first-class seat on Emirates&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tlQs7.jpg&quot; alt=&quot;&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A first-class seat on Qantas&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;That top bed looks very tempting, but I dread to think how much it costs!&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-05T06:12:13.873" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3073" PostTypeId="2" ParentId="751" CreationDate="2014-04-05T13:00:32.530" Score="2" Body="&lt;p&gt;I've flown into Chicago Midway before (as part of my IFR long XC training flight).  It was fun.  :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the USA, if you're IFR they have to take you.  They can refuse VFR flights though.  However, at the ATC seminar I was at the other night, he mentioned that while they have to take IFR flights of any size, nothing says &lt;em&gt;when&lt;/em&gt; they have to take you.  During the airline pushes you may get stuck in a hold for a couple of hours if they've already got a big stack of airliners, so it can be in your best interest to divert elsewhere, hang around on the ground until your hold time would have been up, then just hop over VFR...&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-04-05T13:00:32.530" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3074" PostTypeId="2" ParentId="2507" CreationDate="2014-04-05T14:34:34.303" Score="29" Body="&lt;p&gt;I used to teach sport parachuting, and we occasionally pranked the pilots by shifting the weight around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Cessna 206 set up for parachuting will have all but the pilot's seat removed, the jumpers sit on the floor. Everyone moves forward for takeoff and then sits back for the ride up. The instructor (me) sits on the floor where the co-pilot would normally be, facing aft, everyone else faces forward. I would wait until the plane was trimmed for climb (and well above 1000 feet) and then motion the passengers to come forward a bit (the pilot cannot see this happen). He adjusts trim as usual, thinking nothing of it. Passengers come forward some more. Trim adjusted again. Eventually we have 5 people wearing 20kg packs all jammed up into the first 2 &quot;rows&quot; and the trim almost fully nose up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One signal, and 1/3 of the airplane's gross weight quickly moves almost 2 meters aft (in a 4 meter cabin), followed by a sharp pitch up in both the nose and the pilot's blood pressure. The stall alarm usually goes off too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mid-size tailgate aircraft used for jumping are regularly stalled by too many people on the tailgate for too long. The rule there is stay forward until it's your turn, then go aft and get out (if the buzzer goes, you get out NOW).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's possible to stall a small aircraft by moving the passengers around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scaling this up to airline sizes, we find that the passengers are a rather smaller percentage of the airplane's gross weight, and the presence of things like seats, bulkheads and galleys at the rear prevent 300 people from gathering rapidly at the back. The rather large hydraulically powered elevator also has substantial authority over the aircraft's attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So no, a small group of passengers won't be stalling an airliner out of the sky no matter where they stand. Noticed by the pilots: possibly.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-04-07T11:05:28.437" LastActivityDate="2014-04-07T11:05:28.437" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3076" PostTypeId="1" AcceptedAnswerId="3079" CreationDate="2014-04-05T18:46:11.097" Score="15" ViewCount="3911" Body="&lt;p&gt;After a&lt;a href=&quot;http://chat.stackexchange.com/rooms/12036/conversation/control-gust-locks&quot;&gt; discussion in chat about control surface locks&lt;/a&gt; I was wondering why they need to be locked in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do they need to be locked?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best position to lock them in? up, down, neutral.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="64" LastEditDate="2014-04-05T23:15:07.597" LastActivityDate="2014-04-06T00:14:06.960" Title="Why do parked planes lock the control surfaces?" Tags="&lt;flight-controls&gt;&lt;aircraft-storing&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3077" PostTypeId="2" ParentId="3076" CreationDate="2014-04-05T19:03:13.823" Score="20" Body="&lt;p&gt;In the small planes I fly, it is called a &quot;Gust Lock&quot;, and consists of a small metal bar that fixes the yoke in position, so that the yoke cannot move (left/right, or forward/back), and by association, the ailerons and elevator cannot move either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the name implies, this is for dealing with Gusts of wind... a sudden bit of wind over an unlocked surface can move the surface to its extreme position until it hits a mechanical stop.  If this happens repeatedly, say, over a stormy night, the repeated banging into a mechanical stop can create wear and tear on the surface, the control cables, or the yoke in the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-04-05T19:03:13.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3078" PostTypeId="2" ParentId="3076" CreationDate="2014-04-05T19:04:48.813" Score="6" Body="&lt;p&gt;For gliders (probably other aircraft as well), there are two reasons to fix ailerons, elevator (and rudder) positions: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You want to avoid uncontrolled (potentially damaging) sudden movements caused by (repeated) wind gusts. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you choose or allow unlucky positions/configurations, your plane might exhibit unwanted positional initiative (e.g. an aileron might motivate one wing to lift unexpectedly, hitting heads, tarmac or other obstacles). In mildly gusty conditions, wings are often temporarily fixed by additional weights (usually old tires or similar) to avoid that, too. As mentioned in the comments,  this is not sufficient for anything more than average winds. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2014-04-05T21:24:54.997" LastActivityDate="2014-04-05T21:24:54.997" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3079" PostTypeId="2" ParentId="3076" CreationDate="2014-04-05T23:47:16.613" Score="15" Body="&lt;p&gt;Other folks have already addressed why we want to lock the flight controls when we leave the aircraft - &quot;to prevent damage from gusts of wind&quot;, and &quot;to keep the plane from doing &lt;em&gt;interesting things&lt;/em&gt; in a strong breeze&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the question of the &quot;best&quot; position to lock controls in, for light aircraft the general consensus is that the rudder and ailerons should be locked in the neutral position - In this position any wind blowing over the wings will cause them to lift uniformly, putting tension on the tiedown ropes holding the aircraft to the ground. (If the ailerons are locked at an angle one wing will generate more lift than the other, allowing one of the tiedown ropes to go slack.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elevators are a subject of a little more nuance and debate: It's generally considered best to lock the elevator in the &quot;nose down&quot; position (because any gusts of wind over the tail will push the nose down, rather than encouraging the nose to lift, this also means that those gusts will apply &lt;em&gt;tension&lt;/em&gt; to a tie-down rope located at the tail rather than causing it to go slack).&lt;br&gt;&#xA;On some aircraft locking the elevator in the nose-down (or nose-up) position opens up spaces that birds may try to nest in (&lt;a href=&quot;https://i.stack.imgur.com/dnL5I.jpg&quot; rel=&quot;noreferrer&quot;&gt;for example, check out the tail of this Grumman&lt;/a&gt;) - some pilots prefer to lock the elevator of these aircraft in the neutral position to discourage avian visitors.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Generally it's better to lock the controls than leave them unlocked to bang around in the wind, so on some light aircraft not equipped with control locks pilots use the seatbelt to hold the controls in place. This often results in a &quot;sub-optimal&quot; control position (elevator fully nose-up, ailerons full-deflection left or right), but because the wind speed at which control surfaces may bang against their stops is usually lower than the speed at which the aerodynamically unfavorable control positions will substantially affect the aircraft this is a &quot;lesser of two evils&quot; approach.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-04-06T00:14:06.960" LastActivityDate="2014-04-06T00:14:06.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3084" PostTypeId="1" CreationDate="2014-04-06T04:15:32.677" Score="2" ViewCount="780" Body="&lt;p&gt;Suppose that an enemy plane comes into our radar surveilled airspace, and that this plane is mimicking the signature of a friendly aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can this tactic be recognized? Is there a way of counteracting it?&lt;/p&gt;&#xA;" OwnerUserId="2040" LastEditorUserId="97" LastEditDate="2014-04-07T00:48:45.967" LastActivityDate="2014-04-07T00:48:45.967" Title="Enemy plane detection" Tags="&lt;radar&gt;&lt;military&gt;" AnswerCount="0" CommentCount="4" FavoriteCount="1" ClosedDate="2014-04-06T04:37:41.707" ContentLicense="CC BY-SA 3.0" />
  <row Id="3085" PostTypeId="2" ParentId="3064" CreationDate="2014-04-06T10:01:38.563" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Are there currently any ADs for Boing 777s which would indicate the potential for catastrophic electronic system failures that might explain MH370's transponder failure and other issues?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No one of the ADs issued for 777s can by itself fully explain all the facts of the final flight of MH370/MAS370. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Basic facts&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft was a 777-2H6ER with 53460 flight-hours and 7525 take-offs and landings&lt;/li&gt;&#xA;&lt;li&gt;A 777 has three VHF radios, two HF radios and two transponders.&lt;/li&gt;&#xA;&lt;li&gt;Modern airliners have two main generators, an auxiliary power unit(APU) and a ram-air turbine(RAT) for emergency power. I think the 777 also has backup generators and two independent main power buses.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft left Kuala Lumpur for Beijing on 8 March 2014 at 00:14 local time with 239 passengers and crew on board.&lt;/li&gt;&#xA;&lt;li&gt;Communications were normal up to and including 01:19 when someone on board (believed to be the co-pilot) said to ATC KL &quot;Good night, Malaysian three seven zero&quot;. This was the point at which ATC control is handed to Vietnamese ATC. After there were no further communications from the transponder, the ACARS system or from the VHF radios.&lt;/li&gt;&#xA;&lt;li&gt;Malaysian military reported that their primary radar system records do contain information on an unidentified aircraft to the northwest of Malaysia. The timing, position and heading of the unidentified aircraft in this report are consistent with MH370 changing course away from its intended flight path.&lt;/li&gt;&#xA;&lt;li&gt;MH370 did not arrive at Beijing at 06:30 as scheduled.&lt;/li&gt;&#xA;&lt;li&gt;A satellite communications system on the aircraft continued to respond  to routine hourly handshakes from an Inmarsat ground station via satellite 3-F1 located at 0.0°N (±1.59°), 64.5°E at a height of 35786 km. These normal handshakes ceased after 08:11, there was an unexplained incomplete handshake at 08:19.&lt;/li&gt;&#xA;&lt;li&gt;Subsequent analysis of the handshakes is consistent with MH370 continuing into the southern Indian ocean (and somewhat inconsistent with other routes or it being stationary)&lt;/li&gt;&#xA;&lt;li&gt;Countries within range of the plane's potential flight paths were asked to check their primary radar records for signs of MH370. No country reported finding anything.&lt;/li&gt;&#xA;&lt;li&gt;&lt;s&gt;No part of the aircraft or its contents have been located and firmly identified.&lt;/s&gt;&lt;br&gt;&#xA;Many months later, some parts from the aircraft were washed ashore. &#xA;Investigators report that the condition, timing and location are consistent&#xA;with ocean currents from a point in the south Indian ocean.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Electrical failure hypothesis&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Anyone speculating about the fate of MH370 needs to fit their hypothesis to the above facts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They would have to explain how the failure incapacitated multiple systems within a few minutes and before any of them could be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular what did &lt;strong&gt;NOT&lt;/strong&gt; happen:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pilots did not make an emergency broadcast on VHF&lt;/li&gt;&#xA;&lt;li&gt;The transponder did not squawk any emergency code&lt;/li&gt;&#xA;&lt;li&gt;The ACARS system did not continue normal communication&lt;/li&gt;&#xA;&lt;li&gt;The aircraft did not return to KL and follow procedures for loss of communication.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft did not continue on its planned route&lt;/li&gt;&#xA;&lt;li&gt;The aircraft did not arrive at any of the airfields a pilot should divert to in emergency.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And what &lt;strong&gt;DID&lt;/strong&gt; happen&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft remained airborne for a further 7 hours.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Therefore the engines continued to run&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Electricity was available to a satellite communications system on the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft most likely deviated from its planned route.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;AD 2014-05-03&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgad.nsf/0/d91639a24674ca8f86257c920050edf7/$FILE/2014-05-03.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This AD&lt;/a&gt; issued Feb 18th was reported on in March in connection with MH370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But Reuters &lt;a href=&quot;http://www.reuters.com/article/2014/03/12/us-malaysia-airplane-faa-idUSBREA2B1YN20140312&quot; rel=&quot;nofollow noreferrer&quot;&gt;reports&lt;/a&gt; that Boeing stated this AD does not apply to the aircraft used for flight MH370. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ignore that and look at the consequences of a fuselage crack in the vicinity of the satellite antenna, you can see that this would not turn off the transponder, would not affect the VHF aerials and, if it caused a slow decompression - does not by itself explain why the crew would have failed to respond to the resulting low-pressure alerts by donning oxygen-masks, contacting ATC and descending to a safe altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/C10zk.jpg&quot; alt=&quot;Boeing 777 communication systems diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Occams razor&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A shortage of facts always leads to speculation. Some of which can be very imaginative. The onus of proof is on those producing the hypothesis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are thousands of hypotheses but, in my opinion, the &lt;strong&gt;simplest&lt;/strong&gt; explanation I've read which is consistent with the known facts is deliberate action by a pilot or persons unknown. This doesn't mean it is the right explanation, just that it seems the most probable to me at the moment.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Was the aircraft used for MH370 in compliance with all ADs?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We won't know with any certainty until the investigations branch of the relevant regulatory authority publishes their report on the incident. In previous accidents over an ocean, it has, on at least one occasion, taken years before a final report could be written.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, there have been no confirmed reports, that I can find, of an AD that warned of the potential for catastrophic failures and which should have been applied to 9M-MRO and wasn't.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2019-11-15T17:21:11.517" LastActivityDate="2019-11-15T17:21:11.517" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="3086" PostTypeId="2" ParentId="2530" CreationDate="2014-04-06T13:23:10.170" Score="-4" Body="&lt;p&gt;I think it does -- per the table in &lt;a href=&quot;https://aviation.stackexchange.com/questions/2530/how-close-do-you-have-to-be-to-an-underwater-black-box-to-detect-it/2535#2535&quot;&gt;Danny Beckett's answer&lt;/a&gt; you have a maximum of 7km range. If the black box is 4km deep in the water, you would have to be no more than 3km from it to hear it.&lt;/p&gt;&#xA;" OwnerUserId="2041" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-04-06T23:59:03.980" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3087" PostTypeId="2" ParentId="2952" CreationDate="2014-04-06T14:39:58.320" Score="0" Body="&lt;p&gt;Retired F-111 A-G and EF models, and existing B-1B Lancer aircraft use(d) Terrain Following Radar (TFR) to fly under radar coverage. &lt;/p&gt;&#xA;" OwnerUserId="2043" LastActivityDate="2014-04-06T14:39:58.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3088" PostTypeId="1" AcceptedAnswerId="3095" CreationDate="2014-04-06T23:02:00.347" Score="12" ViewCount="6579" Body="&lt;p&gt;V&lt;sub&gt;NO&lt;/sub&gt;, the airspeed where the green and yellow arcs meet on the airspeed indicator, is the &quot;maximum structural cruising speed&quot; (FAR 1.2). An airplane should only be flown above V&lt;sub&gt;NO&lt;/sub&gt; in calm air. Comparing this to V&lt;sub&gt;A&lt;/sub&gt;, the speed below which the airplane will stall before reaching its load limit, what protection does V&lt;sub&gt;NO&lt;/sub&gt; provide? Turbulence that mimics a full deflection of a control surface would likely qualify as extreme, but what's the middle ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;V&lt;sub&gt;A&lt;/sub&gt; varies by airplane weight. Does V&lt;sub&gt;NO&lt;/sub&gt; vary by weight, and is the calculation the same?&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2014-04-07T04:36:43.247" Title="What protection does Vno provide?" Tags="&lt;aircraft-design&gt;&lt;aircraft-limitations&gt;&lt;airspeed&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3089" PostTypeId="1" AcceptedAnswerId="3091" CreationDate="2014-04-07T02:08:18.613" Score="19" ViewCount="2708" Body="&lt;p&gt;I'm not even sure if they end up falling to earth, or if they accumulate and form/join other clouds or whatnot, which is part of the reason I'm asking this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrails, heavier particles fall faster than the light ones, so as the contrail disperses it spreads vertically as well as horizontally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long does it take for a contrail to fall back to earth if at all?  If they do make it to the ground, is it then water vapor that touches down?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastActivityDate="2014-04-07T02:53:15.417" Title="How long does it take for a contrail to hit the ground?" Tags="&lt;contrails&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ClosedDate="2016-04-06T20:35:42.717" ContentLicense="CC BY-SA 3.0" />
  <row Id="3091" PostTypeId="2" ParentId="3089" CreationDate="2014-04-07T02:27:42.680" Score="25" Body="&lt;p&gt;A contrail is a cirrus cloud composed from water vapor nucleating on soot in the engine exhaust and the contrail itself doesn't fall to the ground.  You will occasionally see cirrus uncinus &quot;mare's tails&quot; form from contrails, which are heavier ice particles in the contrail precipitating from the contrail.  These particles evaporate long before reaching the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jWWV1.jpg&quot; alt=&quot;cirrus uncinus&quot;&gt; &#xA;(image courtesy of Wikipedia, CC licensed)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fate of the contrail cloud itself is death via &lt;a href=&quot;http://glossary.ametsoc.org/wiki/Entrainment&quot; rel=&quot;nofollow noreferrer&quot;&gt;entrainment&lt;/a&gt;.  Watch some over time as they distort from the winds aloft and then mix with the surrounding dry air and evaporate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the contrail is gone and only vapor remains it moves with the air it resides in.  For synoptic scale flows, vertical motion of the atmosphere is on the scale of centimeters per second and as such until that vapor finds its way into subsiding air (e.g. a high pressure system, &lt;a href=&quot;https://courseware.e-education.psu.edu/public/meteo/meteo101demo/Examples/Section9p08.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;the dry conveyor belt of a midlatitude cyclone&lt;/a&gt;), it will tend to remain aloft.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-07T02:27:42.680" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3092" PostTypeId="2" ParentId="3089" CreationDate="2014-04-07T02:53:15.417" Score="11" Body="&lt;p&gt;The vast majority of the output from a jet engine is carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) and water (H&lt;sub&gt;2&lt;/sub&gt;O). The resulting excess of water vapour compared to the surrounding air can cause the water vapour to condense and then freeze, creating the visible contrails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carbon dioxide and water vapour are perfectly normal constituents of the atmosphere, and so do not &quot;fall&quot; to the ground in any meaningful sense. Water molecules in jet exhaust might eventually fall as rain somewhere, but the water cycle as a whole is not significantly affected by contrails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other molecules present in jet exhaust due to impurities in the fuel, but the amount of such impurities is almost certainly negligible.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-04-07T02:53:15.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3094" PostTypeId="1" CreationDate="2014-04-07T04:02:49.450" Score="19" ViewCount="5245" Body="&lt;p&gt;Are there any good resources that teach you how to identify jetliners from the ground? I'd love to see some great comparative photos of their silhouettes. Books or websites are both ok.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, here's a plane that was flying over yesterday en-route to KSFO. I'm guessing it's a 747 or A380, but I can't easily guess from this angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IDdbZ.png&quot; alt=&quot;silhouette of plane from the ground&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="572" LastEditDate="2015-02-19T09:44:33.263" LastActivityDate="2020-11-15T01:27:14.107" Title="How do you visually identify aircraft from the ground?" Tags="&lt;plane-spotting&gt;&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3095" PostTypeId="2" ParentId="3088" CreationDate="2014-04-07T04:23:45.230" Score="12" Body="&lt;p&gt;In short, V&lt;sub&gt;NO&lt;/sub&gt; doesn't provide you any protection, it just tells you that flying that fast puts you in a regime where structural damage will occur before increased load factor will cause a stall -- regardless of weight.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For part 23 airplanes that are not turbine powered and V&lt;sub&gt;D&lt;/sub&gt; has not been established, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8e25e67906c81741372074adddc3a05a&amp;amp;node=14:1.0.1.3.10.7.105.2&amp;amp;rgn=div8&quot;&gt;23.1505&lt;/a&gt;(b) establishes V&lt;sub&gt;NO&lt;/sub&gt; must be established such that it is between V&lt;sub&gt;C,min&lt;/sub&gt; and 0.89*V&lt;sub&gt;NE&lt;/sub&gt;.  Section &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8e25e67906c81741372074adddc3a05a&amp;amp;node=14:1.0.1.3.10.3.70.9&amp;amp;rgn=div8&quot;&gt;23.335&lt;/a&gt; defines V&lt;sub&gt;C&lt;/sub&gt; as a multiplying factor of the square root of wing loading at design maximum takeoff weight.  For normal and utility category airplanes, V&lt;sub&gt;C&lt;/sub&gt; is design cruising speed and is be between 33 √(W/S) and 0.9 V&lt;sub&gt;H&lt;/sub&gt; where W/S is wing loading at the design maximum takeoff weight.  The factor 33 may be scaled as low as 28.6 based on W/S values greater than 20 (the regs do not provide units on any of these numbers...).   V&lt;sub&gt;H&lt;/sub&gt; is the maximum forward airpseed in level flight at maximum continuous power at sea level.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8e25e67906c81741372074adddc3a05a&amp;amp;node=14:1.0.1.3.10.3.70.9&amp;amp;rgn=div8&quot;&gt;23.335&lt;/a&gt; also defines V&lt;sub&gt;A&lt;/sub&gt; and the only relation to V&lt;sub&gt;C&lt;/sub&gt; is that V&lt;sub&gt;A&lt;/sub&gt; need not exceed V&lt;sub&gt;C&lt;/sub&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can see from this information that establishing V&lt;sub&gt;NO&lt;/sub&gt; is a design choice based ultimately upon maximum possible wing loading as a guideline and unlike V&lt;sub&gt;A&lt;/sub&gt; stall speeds are not involved in the calculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you can take from this is that V&lt;sub&gt;A&lt;/sub&gt; will vary by weight (because this affects the stall speed) but V&lt;sub&gt;NO&lt;/sub&gt; is based upon wing loading at max gross takeoff weight and is constant with actual weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying slower than V&lt;sub&gt;A&lt;/sub&gt; you will stall before causing structural damage.  Flying faster than V&lt;sub&gt;A&lt;/sub&gt; you will cause structural damage before stalling the airplane.  V&lt;sub&gt;NO&lt;/sub&gt; will be at least the V&lt;sub&gt;A&lt;/sub&gt; or higher.  Flying below this speed doesn't really tell us anything (V&lt;sub&gt;A&lt;/sub&gt; is better for that), but flying above this speed lets us know the design margins for load factor induced structural damage are such that we don't want bumps or abrupt control deflections because we can damage the airplane.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regulation excerpts. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§23.1505   Airspeed limitations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The maximum structural cruising speed VNO must be established so that it is—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Not less than the minimum value of VC allowed under §23.335; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Not more than the lesser of—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) VC established under §23.335; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) 0.89 VNE established under paragraph (a) of this section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c)(1) Paragraphs (a) and (b) of this section do not apply to turbine airplanes or to airplanes for which a design diving speed VD/MD is established under §23.335(b)(4). For those airplanes, a maximum operating limit speed (VMO/MMO airspeed or Mach number, whichever is critical at a particular altitude) must be established as a speed that may not be deliberately exceeded in any regime of flight (climb, cruise, or descent) unless a higher speed is authorized for flight test or pilot training operations.  &lt;/p&gt;&#xA;  &#xA;  &lt;hr&gt;&#xA;  &#xA;  &lt;p&gt;§23.335   Design airspeeds.&lt;br&gt;&#xA;  Except as provided in paragraph (a)(4) of this section, the selected design airspeeds are equivalent airspeeds (EAS).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Design cruising speed, VC. For VC the following apply:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Where W/S′=wing loading at the design maximum takeoff weight, Vc (in knots) may not be less than—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) 33 √(W/S) (for normal, utility, and commuter category airplanes);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) 36 √(W/S) (for acrobatic category airplanes).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For values of W/S more than 20, the multiplying factors may be decreased linearly with W/S to a value of 28.6 where W/S=100.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) VC need not be more than 0.9 VH at sea level.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Design maneuvering speed VA. For VA, the following applies:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) VA may not be less than VS√n where—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) VS is a computed stalling speed with flaps retracted at the design weight, normally based on the maximum airplane normal force coefficients, CNA; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) n is the limit maneuvering load factor used in design&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The value of VA need not exceed the value of VC used in design.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-04-07T04:36:43.247" LastActivityDate="2014-04-07T04:36:43.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3096" PostTypeId="1" CreationDate="2014-04-07T04:50:46.777" Score="9" ViewCount="923" Body="&lt;p&gt;At a frequency of 37.5 kHz, a quarter wavelength is about 2 km (1.24 miles) long. How does the black box efficiently radiate anything if it is not attached to 2 km of antenna?&lt;/p&gt;&#xA;" OwnerUserId="2049" LastEditorUserId="22726" LastEditDate="2019-04-27T03:42:27.667" LastActivityDate="2019-04-27T03:42:27.667" Title="Do flight recorders need more efficient antennas?" Tags="&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3097" PostTypeId="2" ParentId="3096" CreationDate="2014-04-07T05:37:53.183" Score="18" Body="&lt;p&gt;The short version of the answer is &lt;code&gt;37.5KHz is not &quot;radio frequency&quot;, it's &quot;audio frequency&quot;&lt;/code&gt;, so an antenna is not necessary - just a (very loud) speaker, which is basically what the pinger is.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Specifically, the 37.5KHz &quot;pinger&quot; tones used in the Underwater Locator Beacons that are bolted onto Cockpit Voice Recorder / Flight Data Recorder &quot;black boxes&quot; are in the low end of what we call &lt;a href=&quot;http://en.wikipedia.org/wiki/Ultrasound&quot;&gt;ultrasonic frequencies&lt;/a&gt;. Water is &lt;a href=&quot;http://en.wikipedia.org/wiki/Underwater_acoustics&quot;&gt;generally a good conductor of sound&lt;/a&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Thermocline&quot;&gt;with at least one notable exception&lt;/a&gt;), so it is usually possible for sonar detection equipment to &quot;hear&quot; the pinger tones at reasonable distances (with the interpretation of &quot;reasonable&quot; varying based on the depth of the area being searched - much like in air the sound intensity falls off as distance from the source increases, so if we're listening at the surface of the ocean a pinger in 500 feet of water will have a larger coverage footprint than the same pinger in 5000 feet of water).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1289" LastEditDate="2014-04-07T08:25:07.107" LastActivityDate="2014-04-07T08:25:07.107" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3098" PostTypeId="2" ParentId="3094" CreationDate="2014-04-07T05:48:34.627" Score="10" Body="&lt;p&gt;The canonical reference for aircraft recognition would be &lt;a href=&quot;http://en.wikipedia.org/wiki/Jane&amp;#39;s_All_the_World&amp;#39;s_Aircraft&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;Jane's All the World's Aircraft&lt;/em&gt;&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net&quot; rel=&quot;nofollow&quot;&gt;http://www.airliners.net&lt;/a&gt; is also a useful resource, but generally means working from photos - the line drawings in &lt;em&gt;Jane's&lt;/em&gt; are often easier to use because they abstract away things like airline liveries and distill the aircraft down to its basic shapes.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-04-03T04:21:25.427" LastActivityDate="2015-04-03T04:21:25.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3100" PostTypeId="2" ParentId="2530" CreationDate="2014-04-07T06:43:21.397" Score="0" Body="&lt;p&gt;3km..just one mile away from the source. They must be right over it, if they heard the ping for  2 hours 20 minutes. But the Chinese guys with the more primitive gear...what were they hearing...maybe the other recorder.&lt;/p&gt;&#xA;" OwnerUserId="2050" LastActivityDate="2014-04-07T06:43:21.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3101" PostTypeId="1" AcceptedAnswerId="3102" CreationDate="2014-04-07T10:33:34.230" Score="4" ViewCount="492" Body="&lt;p&gt;The pictures of flight data recorders show that the location beacon (pinger) is outside the main protection encasement:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Ta1w.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Is it really a good idea to keep such a vital instrument unprotected? Or is that round metallic thing strong enough to resist impact and fire?&lt;/p&gt;&#xA;" OwnerUserId="1534" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-07T15:57:48.653" Title="What protects the location beacon (pinger) of a flight data recorder?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3102" PostTypeId="2" ParentId="3101" CreationDate="2014-04-07T15:22:19.930" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is it really a good idea to keep such a vital instrument unprotected? Or is that round metallic thing strong enough to resist impact and fire?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The casing of the ULB is itself designed to be strong enough to withstand the forces expected when an airliner crashes into an ocean, lake or large river (which are the only circumstances where a ULB is useful).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.youtube.com/watch?v=mQehX0rVYuY&quot; rel=&quot;nofollow noreferrer&quot;&gt;teardown video&lt;/a&gt; starting at around 4:45&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Copies of the &lt;a href=&quot;http://www.rjeint.com/pdf/TSO_C121.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;relevant standards&lt;/a&gt; cost $70 each. However, a &lt;a href=&quot;http://www.fire.tc.faa.gov/pdf/na68-7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;1968 report&lt;/a&gt; from the early days of ULB development says&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gLgbH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/64/voretaq7&quot;&gt;voretaq7&lt;/a&gt; notes in a comment: ULBs need to be external to the FDR/CVR canister because they need to have batteries changed regularly without affecting the integrity of the data recorder canister.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-04-07T15:57:48.653" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3103" PostTypeId="1" AcceptedAnswerId="3104" CreationDate="2014-04-07T16:43:30.617" Score="31" ViewCount="30608" Body="&lt;p&gt;Primary electric power on larger airplanes is provided as AC. What aspects of aircraft make AC a better choice than DC?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T20:16:10.527" LastActivityDate="2018-01-17T20:18:56.037" Title="Why do airplanes use AC electric power?" Tags="&lt;aircraft-systems&gt;&lt;electrical-system&gt;" AnswerCount="7" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3104" PostTypeId="2" ParentId="3103" CreationDate="2014-04-07T17:00:13.183" Score="18" Body="&lt;p&gt;AC is easier to produce with the engines, that act as generators. &#xA;The engines have a rotating shaft that it is easily equipped with magnetic dipoles all around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sb1K6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, depending on the instrument, the current is either used directly or, by the use of converters, in DC form as not only it is easier to produce, it is also easier to convert. So electronic devices that uses 12, 5 or 3V may contain their own voltage converter (though this is less and less true with modern efficient switch-mode converters). If DC conversion was as much efficient as AC conversion, we wouldn't see high-voltage lines. Last but not least, it's easier to switch, because the current is null twice per cycle. DC must be switched at full current, which is expensive and weight costly. (thanks mins)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-05-01T14:24:15.780" LastActivityDate="2016-05-01T14:24:15.780" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="3105" PostTypeId="2" ParentId="3103" CreationDate="2014-04-07T17:06:29.857" Score="7" Body="&lt;p&gt;Does it have to be aircraft-specific reasons? I would imagine the reasons are not necessarily very aircraft related:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Different subsystems need different working voltages internally, and supplying AC makes it easy for each component to transform down to whatever it needs.&lt;/li&gt;&#xA;&lt;li&gt;Where mechanical power is needed, asynchronous AC motors are a lot simpler (especially in terms of maintenance requirements) than DC motors.&lt;/li&gt;&#xA;&lt;li&gt;Engineering inertia. All kinds of components already come expecting AC; even if DC is &lt;em&gt;in isolation&lt;/em&gt; superior for some uses (as it might well be for electronics, with today's solid-state voltage converters) supplying DC to aircraft systems would mean that you need to have a DC supply network &lt;em&gt;in addition&lt;/em&gt; to the AC supply for those components that are not yet available and certified in DC versions. That extra wiring alone might easily offset the advantages of having some of power supplies be lighter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-04-07T17:06:29.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3106" PostTypeId="2" ParentId="3094" CreationDate="2014-04-07T17:26:21.627" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0618411275&quot;&gt;A Field Guide to Airplanes&lt;/a&gt; is also really good. I find it better than &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0061346195&quot;&gt;Jane's Aircraft Recognition Guide&lt;/a&gt; because it is categorized by aircraft appearance, and also is written like a field guide as opposed to a reference book.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-04-07T17:26:21.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3107" PostTypeId="2" ParentId="3103" CreationDate="2014-04-07T18:16:16.913" Score="15" Body="&lt;p&gt;What the other answers have failed to note is that on a plane, its not just AC power, but 3 phase AC power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on how the plane is wired up, you will either get the benefit of reduced cable weight or higher reliability (or some blend of the two).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Delta&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane is wired up with a Delta transformer, then 3 wires are used to carry the electricity. However, what is crazy is that the Delta transformer (or alternator) will continue to run (albeit at a lower capacity) with one of the windings destroyed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wye&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a balanced wye configuration the 4 wires come from the transformer. Each of the first three wires carry current from the transformer, with the 4th as the common &quot;return&quot;. However since each of the wires are &quot;balanced&quot;, the actual current on the common is approximately zero (and not the 3 * current of the output). That means your 3 &quot;live&quot; wires only needs to be thick enough to carry the current one way. (typically with DC you would need to have wire thickness to carry the current there then back again). So in effect we can achieve the same power transmission with half the weight of a DC setup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since on planes, both redundancy (safety) and weight (economy) are both massive factors in cost. It is actually economical to run power on AC, and convert to DC where necessary.&lt;/p&gt;&#xA;" OwnerUserId="600" LastEditorUserId="600" LastEditDate="2016-05-01T17:25:04.783" LastActivityDate="2016-05-01T17:25:04.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3108" PostTypeId="2" ParentId="3103" CreationDate="2014-04-07T20:29:28.763" Score="12" Body="&lt;p&gt;The size, weight, and cost of switchgear for DC-DC conversion at any given power is much higher than AC-AC and AC-DC conversion. So whether a piece of equipment requires AC or DC, it can be converted more easily from an AC source than from a DC source - but more importantly, it can be done with less weight, volume, and cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the same reason 400Hz is used rather than 50Hz or 60Hz - weight.  A generator or transformer that can handle a given load is physically smaller and lighter at higher frequencies due to issues with core saturation at lower frequencies.  A smaller, lighter core can be used for higher frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While switchgear has evolved over the decades, and weight and cost aren't as big an issue as they were in the past, the generator itself still has to have a stator and windings, and these are still physically smaller and lighter for a given power output than the equivalent DC, or low frequency AC generator.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2014-04-07T20:29:28.763" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3109" PostTypeId="1" AcceptedAnswerId="3144" CreationDate="2014-04-07T21:58:44.047" Score="23" ViewCount="3887" Body="&lt;p&gt;Suppose you're on your private pilot checkride and the tower gives you a land and hold short clearance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are you &lt;em&gt;able&lt;/em&gt; to accept that clearance? I know you're expected to fly as if you were a private pilot, and you're allowed to carry the examiner even though they're not providing you dual instruction...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are you allowed to accept a clearance on your private pilot checkride that you couldn't accept as a student but could as a private pilot?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2020-04-01T02:44:38.160" Title="Can you accept a LAHSO on your private pilot checkride?" Tags="&lt;faa-regulations&gt;&lt;checkride&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3110" PostTypeId="5" CreationDate="2014-04-07T22:28:30.530" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:28:30.530" LastActivityDate="2014-04-07T22:28:30.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3111" PostTypeId="4" CreationDate="2014-04-07T22:28:30.530" Score="0" Body="The white lines sometimes seen in the sky trailing an aircraft." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-07T22:31:39.393" LastActivityDate="2014-04-07T22:31:39.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3112" PostTypeId="5" CreationDate="2014-04-07T22:35:46.407" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:35:46.407" LastActivityDate="2014-04-07T22:35:46.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3113" PostTypeId="4" CreationDate="2014-04-07T22:35:46.407" Score="0" Body="The section of flight between the after takeoff climb and landing approach. " OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T01:13:11.740" LastActivityDate="2014-04-08T01:13:11.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3114" PostTypeId="5" CreationDate="2014-04-07T22:37:52.160" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:37:52.160" LastActivityDate="2014-04-07T22:37:52.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3115" PostTypeId="4" CreationDate="2014-04-07T22:37:52.160" Score="0" Body="The operation after an accident that tries to rescue the survivors." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T01:13:18.470" LastActivityDate="2014-04-08T01:13:18.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3116" PostTypeId="5" CreationDate="2014-04-07T22:38:32.803" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:38:32.803" LastActivityDate="2014-04-07T22:38:32.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3117" PostTypeId="4" CreationDate="2014-04-07T22:38:32.803" Score="0" Body="Airplane with 2 wings stacked on top of each other." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T02:04:23.047" LastActivityDate="2014-04-08T02:04:23.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3118" PostTypeId="5" CreationDate="2014-04-07T22:40:33.050" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:40:33.050" LastActivityDate="2014-04-07T22:40:33.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3119" PostTypeId="4" CreationDate="2014-04-07T22:40:33.050" Score="0" Body="The main body of the airplane that holds the cargo and passengers." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T01:12:57.917" LastActivityDate="2014-04-08T01:12:57.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3120" PostTypeId="5" CreationDate="2014-04-07T22:41:56.377" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:41:56.377" LastActivityDate="2014-04-07T22:41:56.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3121" PostTypeId="4" CreationDate="2014-04-07T22:41:56.377" Score="0" Body="Military airplane designed to carry and drop bombs on targets." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T01:12:53.533" LastActivityDate="2014-04-08T01:12:53.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3122" PostTypeId="5" CreationDate="2014-04-07T22:45:53.183" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:45:53.183" LastActivityDate="2014-04-07T22:45:53.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3123" PostTypeId="4" CreationDate="2014-04-07T22:45:53.183" Score="0" Body="The designs Airliners are painted with. These are typically designs of the company owning or leasing the plane." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-07T23:03:19.367" LastActivityDate="2014-04-07T23:03:19.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3124" PostTypeId="5" CreationDate="2014-04-07T22:47:41.657" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:47:41.657" LastActivityDate="2014-04-07T22:47:41.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3125" PostTypeId="4" CreationDate="2014-04-07T22:47:41.657" Score="0" Body="Oxygen deprivation as a result of the low air-pressure at high altitude." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T01:13:02.053" LastActivityDate="2014-04-08T01:13:02.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3126" PostTypeId="5" CreationDate="2014-04-07T22:48:45.400" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:48:45.400" LastActivityDate="2014-04-07T22:48:45.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3127" PostTypeId="4" CreationDate="2014-04-07T22:48:45.400" Score="0" Body="Event where pilots in mostly sports planes come to show off their skills." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T02:03:41.037" LastActivityDate="2014-04-08T02:03:41.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3128" PostTypeId="5" CreationDate="2014-04-07T22:50:34.757" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:50:34.757" LastActivityDate="2014-04-07T22:50:34.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3129" PostTypeId="4" CreationDate="2014-04-07T22:50:34.757" Score="0" Body="National Transportation and Safety Board, an American organization in charge of investigating incidents in America." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-07T23:31:11.693" LastActivityDate="2014-04-07T23:31:11.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3130" PostTypeId="5" CreationDate="2014-04-07T22:52:54.110" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:52:54.110" LastActivityDate="2014-04-07T22:52:54.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3131" PostTypeId="4" CreationDate="2014-04-07T22:52:54.110" Score="0" Body="An Irish budget airline operating Boeing 737-800 aircraft in Europe." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T02:03:52.667" LastActivityDate="2014-04-08T02:03:52.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3132" PostTypeId="5" CreationDate="2014-04-07T22:54:05.683" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:54:05.683" LastActivityDate="2014-04-07T22:54:05.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3133" PostTypeId="4" CreationDate="2014-04-07T22:54:05.683" Score="0" Body="Remote control model aircraft" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T02:03:45.957" LastActivityDate="2014-04-08T02:03:45.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3134" PostTypeId="5" CreationDate="2014-04-07T22:54:05.957" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:54:05.957" LastActivityDate="2014-04-07T22:54:05.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3135" PostTypeId="4" CreationDate="2014-04-07T22:54:05.957" Score="0" Body="Boarding as it relates to the airline/carrier operations; for passenger related questions, visit Travel Stack Exchange." OwnerUserId="609" LastEditorUserId="14897" LastEditDate="2019-02-19T19:07:23.850" LastActivityDate="2019-02-19T19:07:23.850" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3136" PostTypeId="5" CreationDate="2014-04-07T22:55:17.200" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T22:55:17.200" LastActivityDate="2014-04-07T22:55:17.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3137" PostTypeId="4" CreationDate="2014-04-07T22:55:17.200" Score="0" Body="Wing devices on the end of the wing for aerodynamic purposes." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-07T23:31:27.043" LastActivityDate="2014-04-07T23:31:27.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3138" PostTypeId="5" CreationDate="2014-04-07T23:01:33.457" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T23:01:33.457" LastActivityDate="2014-04-07T23:01:33.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3139" PostTypeId="4" CreationDate="2014-04-07T23:01:33.457" Score="0" Body="A British budget airline operating Airbus A320 aircraft in Europe" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T05:58:10.840" LastActivityDate="2014-04-08T05:58:10.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3140" PostTypeId="5" CreationDate="2014-04-07T23:03:43.030" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-07T23:03:43.030" LastActivityDate="2014-04-07T23:03:43.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3141" PostTypeId="4" CreationDate="2014-04-07T23:03:43.030" Score="0" Body="The German national airline, operating mixed Boeing &amp; Airbus aircraft globally." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-08T02:03:29.287" LastActivityDate="2014-04-08T02:03:29.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3144" PostTypeId="2" ParentId="3109" CreationDate="2014-04-08T00:18:47.767" Score="13" Body="&lt;p&gt;First, let's see whether it's &lt;em&gt;legal&lt;/em&gt;. &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/7110.118.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 7110.118&lt;/a&gt; notes that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;7. EXPLANATION OF CHANGES.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The following changes apply to all LAHSO. &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;a. ...&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;b. Solo student pilots will not conduct LAHSO. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, you &lt;em&gt;could&lt;/em&gt; interpret that as not applicable to your situation, as you are not the sole occupant of the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8f535102b6bc505633a3b12966a427b0&amp;amp;node=14:2.0.1.1.2.3.1.4&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §61.87&lt;/a&gt;&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;(a) &lt;em&gt;General.&lt;/em&gt; ... The term &quot;solo flight&quot; as used in this subpart means that flight time during which a student pilot is the sole occupant of the aircraft...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though it might be allowed, note it does not say &lt;em&gt;must&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html#aim0403.html.13&quot; rel=&quot;noreferrer&quot;&gt;AIM 4-3-11(b)&lt;/a&gt;&lt;/h2&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;...&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Student pilots or pilots not familiar with LAHSO &lt;strong&gt;should&lt;/strong&gt; not participate in the program.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'd recommend against doing so because LAHSO can add to your workload, especially if you're a bit nervous on your checkride. Also, the AIM note on discouraging LAHSO is rather valid and if done improperly, can affect safety. Having said that, the examiner is likely to ask questions on LAHSO during your practical examination, especially since &lt;a href=&quot;http://max.aero/flight-training-programs/private-pilot-pts-explained/private-pilot-pts-the-introduction-section/private-pilot-pts-the-introduction-section-special-emphasis-areas/&quot; rel=&quot;noreferrer&quot;&gt;LAHSO is a special emphasis area in the PTS&lt;/a&gt;. This may include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Requirements to accept a LAHSO clearance&lt;/li&gt;&#xA;&lt;li&gt;ATC pharseology for LAHSO&lt;/li&gt;&#xA;&lt;li&gt;Pilot responsibilities while carrying out LAHSO&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In any case, always remember that &lt;strong&gt;you do not need to accept a LAHSO clearance&lt;/strong&gt; -- if you do not feel comfortable with doing so, ATC will provide arrangements to land full-length on the same runway or another one. &lt;strong&gt;You should not accept a LAHSO clearance if you believe doing so would compromise safety.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; this does &lt;em&gt;not&lt;/em&gt; necessarily apply to all situations where a student pilot is prohibited from doing something that a private pilot would be able to do.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-04-14T23:57:13.197" LastActivityDate="2014-04-14T23:57:13.197" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3145" PostTypeId="2" ParentId="3039" CreationDate="2014-04-08T01:15:40.333" Score="32" Body="&lt;p&gt;AOPA has an article under Pilot Resources that specifically covers this situation called &lt;a href=&quot;https://www.aopa.org/Pilot-Resources/Learn-to-Fly/Aviation-Subject-Report-Logging-Pilot-in-Command-PIC-Time.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Logging Pilot-in-Command (PIC) Time&lt;/a&gt; (emphasis added by me):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unlike driving cars, &lt;strong&gt;the PIC may allow anyone, including a non-pilot&lt;/strong&gt;,&#xA;  a pilot who may not legally act as pilot in command, or another fully&#xA;  qualified pilot fly the airplane, or be &quot;sole manipulator of the&#xA;  controls&quot; during the flight. The PIC is not required to sit in the&#xA;  left pilot seat. Regardless of where the PIC is sitting in the&#xA;  airplane or who is manipulating the controls, the PIC is ultimately&#xA;  responsible and accountable for the safety and operation of the&#xA;  flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are the PIC letting someone else fly, remember (like they say above) that you are still responsible for &lt;strong&gt;everything&lt;/strong&gt; that they do, so make sure that you never put yourself in a situation where you are not able to maintain (or regain, if necessary) control of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would recommend that you carefully brief the passenger about not fighting you on the controls and to &lt;strong&gt;&lt;em&gt;immediately&lt;/em&gt;&lt;/strong&gt; let go if you tell them to.  Do this &lt;strong&gt;before&lt;/strong&gt; you let them fly and be clear that it is about flight safety.   Most of them will be listening carefully once you say that.  :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have done this plenty of times, and another thing you can do (especially when at lower altitudes) is to keep your hands and feet on the controls at all times so that you can stop them from doing anything too out there. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now that being said, air carrier regulations specifically prohibit pilots from letting passengers fly so the above would only apply to private flights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3218cb34fdd8cfed907ea78fa03d75db&amp;amp;node=14:3.0.1.1.11.2.3.33&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;§135.115   Manipulation of controls.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No pilot in command may allow any person to manipulate the flight&#xA;  controls of an aircraft during flight conducted under this part, nor&#xA;  may any person manipulate the controls during such flight unless that&#xA;  person is—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) A pilot employed by the certificate holder and qualified in the&#xA;  aircraft; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) An authorized safety representative of the Administrator who has&#xA;  the permission of the pilot in command, is qualified in the aircraft,&#xA;  and is checking flight operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=468ceb9f161f88438d6f92d79dcdb3a8&amp;amp;node=14:3.0.1.1.7.20.3.11&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;§121.545   Manipulation of controls.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No pilot in command may allow any person to manipulate the controls of&#xA;  an aircraft during flight nor may any person manipulate the controls&#xA;  during flight unless that person is—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) A qualified pilot of the certificate holder operating that&#xA;  aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) An authorized pilot safety representative of the Administrator or&#xA;  of the National Transportation Safety Board who has the permission of&#xA;  the pilot in command, is qualified in the aircraft, and is checking&#xA;  flight operations; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) A pilot of another certificate holder who has the permission of&#xA;  the pilot in command, is qualified in the aircraft, and is authorized&#xA;  by the certificate holder operating the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2019-12-19T18:22:59.477" LastActivityDate="2019-12-19T18:22:59.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3146" PostTypeId="1" CreationDate="2014-04-08T01:41:58.387" Score="15" ViewCount="2518" Body="&lt;p&gt;The question &lt;a href=&quot;https://aviation.stackexchange.com/questions/3039/are-you-allowed-to-let-passengers-fly-the-plane#3039&quot;&gt;Are pilots allowed to let passengers fly the plane?&lt;/a&gt; is interesting to read, noting that pilots &lt;em&gt;are&lt;/em&gt; permitted to allow passengers to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recall an Air Crash Investigation episode (&lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow noreferrer&quot;&gt;AFL593&lt;/a&gt;) where the pilot pretended to allow his son to manipulate the controls of an airliner, without realising the autopilot had been disconnected, resulting in an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering how commonplace this is? Is this an isolated incident?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip-side, I've heard of at least 3 occasions where passengers have successfully landed planes, e.g:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/TKpHrmHrwnU?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-01T19:23:21.810" Title="Have any passengers crashed planes?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;accidents&gt;" AnswerCount="4" CommentCount="19" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3147" PostTypeId="2" ParentId="3146" CreationDate="2014-04-08T01:54:32.793" Score="14" Body="&lt;p&gt;No passengers have crashed an airplane while the pilot was letting them fly.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this situation, the &lt;strong&gt;PIC&lt;/strong&gt; crashed the plane because he didn't do his job as the captain and final authority for the safe operation of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Letting a passenger fly would most likely be listed as a &quot;contributing factor&quot; by investigators looking into an accident where this happened, but responsibility for the crash lies squarely on the PIC.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-08T01:54:32.793" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3148" PostTypeId="1" AcceptedAnswerId="3152" CreationDate="2014-04-08T01:58:50.190" Score="17" ViewCount="1881" Body="&lt;p&gt;How does someone request a &lt;a href=&quot;https://aviation.stackexchange.com/questions/2131/where-can-faa-letters-of-interpretation-be-found&quot;&gt;letter of interpretation&lt;/a&gt; from the FAA if a particular situation surrounding a regulation or policy is not clear?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-04-08T17:09:48.073" Title="How can someone get clarification from the FAA on the intent of a regulation?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3149" PostTypeId="1" AcceptedAnswerId="3151" CreationDate="2014-04-08T03:19:10.733" Score="12" ViewCount="1625" Body="&lt;p&gt;In the AF447 incident, the autopilot system was offline due to the aircraft's pitot tubes being obstructed by ice particles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the physical condition of the plane in air is cold and risky, the same physical obstruction could happen again and again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though the pilot is trained to fly the plane in bad weather, I'm wondering why not just use the GPS to aid the plane's computer? The GPS system could be a secondary source to providing the computer with information for flying, like speed and altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the GPS could've aided AF447 in preventing the autopilot system from going offline, would the pitot's issue not to initialize the system problem then crash a plane?&lt;/p&gt;&#xA;" OwnerUserId="2060" LastEditorUserId="3201" LastEditDate="2016-01-30T21:43:23.150" LastActivityDate="2020-06-22T20:25:54.777" Title="Could the GPS be used to aid the autopilot with speed?" Tags="&lt;safety&gt;&lt;autopilot&gt;&lt;gnss&gt;&lt;af447-accident&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3150" PostTypeId="2" ParentId="3149" CreationDate="2014-04-08T04:06:41.403" Score="17" Body="&lt;p&gt;The main issue is that we can only get groundspeed from GPS data. Winds aloft aren't known exactly at a particular place, so they could be rather inaccurate -- certainly not enough to leave to the hands of the autopilot. The decision to use GPS data to &lt;em&gt;verify&lt;/em&gt; airspeed would lie in the hands of the crew. Anyway, they were too preoccupied to go and check that their ground speed was sort of accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not uncommon for winds aloft to reach speeds between 180 and 200 knots. While previous weather reports can be useful, winds can change quite frequently -- the chances of the wind changing is much more than the chances of all the sources of airspeed becoming unreliable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS data is also not 100% accurate, so keep that in mind, especially if only some of the sattelites can be reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the crash came down to was mainly a loss of situational awareness, combined with their lack of experience with actual stall recovery, was the main contributing factor to the accident.&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-04-08T04:06:41.403" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3151" PostTypeId="2" ParentId="3149" CreationDate="2014-04-08T04:27:26.100" Score="17" Body="&lt;p&gt;GPS speed is already available to the crew, although not in an easy to see place.  It isn't designed to cross-check other instruments because it is showing entirely different information.  The winds are changing the actual speed of the airplane across the ground (which GPS shows) and altitude affects the air density (which changes the airspeed shown on the airspeed indicator).  The difference between the two can be vast, with no easy correlation.  Altitude has similar issues, although not as severe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if they could be &quot;synced up&quot;, the problem comes in when there is a &lt;em&gt;difference&lt;/em&gt; between the two.  Which do you trust?  GPS receivers can (and do) fail, and could show an incorrect speed as well.  When the computer gets conflicting information like it did between the different systems in the AF447 accident, it gives control to the pilot to sort out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the time that the autopilot disconnected until the ice blocking the pitot system melted away, only 12 seconds passed.  During that time the crew stalled the airplane and then a chain of events ultimately resulted in the crash of a perfectly functioning airplane.  The exact same thing had happened numerous times before then without resulting in a crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the fact, the NTSB identified numerous factors and made recommendations to improve crew training (which has been implemented) and hardware/software modifications to the airplane.  Aviation very much takes a &quot;continuous improvement&quot; view of things, trying to learn from every accident and to try to prevent the same thing from happening again.  Based on what I've seen, I &lt;em&gt;doubt&lt;/em&gt; that this exact same scenario will play out again.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-08T04:27:26.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3152" PostTypeId="2" ParentId="3148" CreationDate="2014-04-08T05:23:01.197" Score="13" Body="&lt;p&gt;Generally there are two ways to get an interpretation of regulations from the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first (less-formal) way would be to call or email your &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot;&gt;local FSDO&lt;/a&gt; with your question -- they will usually get back to you pretty quickly with a verbal opinion or an email (on the two occasions I've contacted the local FSDO I've gotten an answer within 1-2 days).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interpretations from your local FSDO are essentially valid within their coverage area (if you get an opinion from Farmingdale in New York the folks in Los Angeles, California may not honor it).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The second (very formal) way is to write an actual on-paper letter to the FAA's office of the chief counsel requesting a legal interpretation of some specific regulation(s) and &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/contacts/?passedOrg=2&quot;&gt;mail it to their office&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Office of the Chief Counsel&#xA;800 Independence Avenue SW&#xA;Washington, DC 20591 &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This request should be as specific as you can make it, for example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;May the FAA hold a person who performs maintenance on an aircraft responsible for the proper performance of that maintenance under 43.13(a) and (b) when that person was not the person who made the maintenance record entry required by 43.9?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If your request is inspired by some ongoing action (say a warning letter) you should reference it and include a copy to help speed things along.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA's legal staff will chew on the request for a while, and eventually produce &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2014/Romigh%20-%20%282014%29%20Legal%20Interpretation.pdf&quot;&gt;a legal interpretation&lt;/a&gt; (the linked interpretation, which answers the example question above, took about 5 months, and it is a relatively simple interpretation - The more complex the regulation that needs to be interpreted the longer it will probably take).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Counsel interpretations are organization-wide precedent, and &lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/Supporting%20General%20Aviation/Advocacy/Regulatory%20&amp;amp;%20Certification%20Policy/Regulatory%20Brief%20FAA%20issues%20new%20interpretation%20of%20dual%20controls/dual_letter1.pdf&quot;&gt;on occasion they can overrule opinions/decisions from a FSDO&lt;/a&gt;. They are effective &quot;The Final Word&quot; on how regulations are to be applied (unless overturned in court).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-04-08T17:09:48.073" LastActivityDate="2014-04-08T17:09:48.073" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3153" PostTypeId="2" ParentId="3149" CreationDate="2014-04-08T07:43:56.670" Score="5" Body="&lt;p&gt;The important quantity, measured by pitot probes, indicated airspeed, is &lt;em&gt;not a speed at all&lt;/em&gt;. It is a dynamic pressure. Since lift also depends on dynamic pressure and angle of attack, the right backup is angle of attack indicator. In fact it is angle of attack that matters most, but it can't be measured as precisely, so airspeed is used as primary indicator. All transport category aircraft are equipped with angle-of-attack vanes.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-04-08T07:43:56.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3154" PostTypeId="5" CreationDate="2014-04-08T07:57:11.183" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-08T07:57:11.183" LastActivityDate="2014-04-08T07:57:11.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3155" PostTypeId="4" CreationDate="2014-04-08T07:57:11.183" Score="0" Body="The wheels of an airplane. Sometimes replaced by floats or skis." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-08T13:05:30.847" LastActivityDate="2014-04-08T13:05:30.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3156" PostTypeId="2" ParentId="3103" CreationDate="2014-04-08T10:08:16.793" Score="3" Body="&lt;p&gt;I assume that aeroplanes use both AC and DC for powering the various subsystems:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If energy has to be stored in accumulators - well, they only store DC current. But&#xA;if generators are involved you won't have a chance of totally avoiding AC since a rotating movement is essentially sinusoidal:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you put a rotating magnet into a coil it will produce an alternating magnetic field in the coil =&gt; the coil will produce AC&lt;/li&gt;&#xA;&lt;li&gt;and if you put a rotating coil into a magnetic field the field will alternate between going through the coil in one direction and in the other again producing AC current.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One can now put the AC through a rectifier or use a wiper (a switch that can reverse the current and is mechanically triggered twice at every revolution of the generator). But if you rectify a sinus you still get a voltage that goes up and down, only it no more passes the zero level. This means you will sometimes draw too much energy from the generator (when the voltage is high) and at every revolution the voltage will shortly drop to zero meaning you won't be able to draw any energy at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't constantly draw energy from a generator, the generator will vibrate.&#xA;You wouldn't like that in an aeroplane but there is a remedy: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using three-phase AC: You can generate three sine waves with the same generator using coils that are a third of a revolution apart. When the voltage from one of these coils drops, the voltage at the two other coils rises - and the power produced (which is linear to the voltages squared) will add up to a constant flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next thing one has to know that if you want a constant stream of power from a motor the same reasons make you use three AC waves here, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally this AC is generated from a DC voltage, though, because you might want to adjust the frequency the motor is running at or the amount of power it provides hence you want to adjust the frequency of the voltage the motor gets.  &lt;/p&gt;&#xA;" OwnerUserId="2065" LastEditorUserId="97" LastEditDate="2014-04-08T23:24:09.437" LastActivityDate="2014-04-08T23:24:09.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3157" PostTypeId="1" AcceptedAnswerId="3158" CreationDate="2014-04-08T10:26:12.367" Score="4" ViewCount="513" Body="&lt;p&gt;Black boxes put out a sonar ping at about 32kHz. From what I've read, depending on sea conditions the ping will be audible at the surface out to about 16 km, leaving a search area of around 1024 square km.&#xA;By adding a little complexity to the ping circuit, you could encode within it the last received GPS position of the box, before it hits the water. With average sea depth and average sink angles of less than 45° that information would cut the search area down to about 10 square km.&#xA;Is there some reason this tech is not used, or is it still in the rigorous testing pipeline these devices must go through?&lt;/p&gt;&#xA;" OwnerUserId="2069" LastActivityDate="2015-01-19T17:00:43.700" Title="Could you encode data in a Black Box ping?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3158" PostTypeId="2" ParentId="3157" CreationDate="2014-04-08T10:54:37.593" Score="6" Body="&lt;p&gt;Current underwater locator beacons (ULBs) have a detection range of only a few km. 16 km would be under exceptionally favourable conditions. So in most cases the GPS data would not be of any additional help. It might tell you where the aircraft was before it hit the water, not exactly where the debris ended up after falling through several Km of water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An advantage of current ULBs is their extreme simplicity and small size. There's no need for external data-feed and power connections. There are no issues of openings in the casing for waterproof connectors that also need to withstand the g-forces and pressures expected to be endured by a ULB. They are easy to test regularly and relatively easy to maintain.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From what I have read, current proposals for improvements to ULBs mostly focus on&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;increase duration from 30 days to 90 days&lt;/li&gt;&#xA;&lt;li&gt;increase range by &lt;a href=&quot;https://aviation.stackexchange.com/questions/2530/how-close-do-you-have-to-be-to-an-underwater-black-box-to-detect-it&quot;&gt;changing frequency&lt;/a&gt; from 37.5 kHz to ~10KHz&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are trade-offs here - longer duration means bigger batteries. changing the frequency may make it harder to distinguish from other sources of sound in the ocean.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;An interesting &lt;a href=&quot;https://fenix.tecnico.ulisboa.pt/downloadFile/2589871808139/dissertacao.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;2011 dissertation&lt;/a&gt; describes the difficulties involved  and discusses modulating the beacon signal to include data.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-04-08T22:28:15.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3159" PostTypeId="2" ParentId="3157" CreationDate="2014-04-08T11:02:19.213" Score="-2" Body="&lt;p&gt;Main reason those signals can be distinguished for what they are is because they have a specific signature. If the signals were to change all the time because you mix in extra information, they'd be impossible to recognise and thus useless.&lt;br/&gt;&#xA;Combined with the short range of the signal (inevitable consequence of the need to be low power, anything more would mean heavier equipment and/or shorter lifespan), there's just no benefit.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-04-08T11:02:19.213" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3160" PostTypeId="1" AcceptedAnswerId="3161" CreationDate="2014-04-08T12:18:10.677" Score="12" ViewCount="3755" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/3109/can-you-accept-a-lahso-on-your-private-pilot-checkride&quot;&gt;this question&lt;/a&gt; and I want to know what this term means. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;land and hold short clearance&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-24T14:22:49.323" Title="What is a land and hold short clearance (LAHSO)?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3161" PostTypeId="2" ParentId="3160" CreationDate="2014-04-08T12:23:31.560" Score="15" Body="&lt;p&gt;It means that you can land on the runway but must hold short (read: do not cross) before some point on the runway.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faraim.org/aim/aim-4-03-14-199.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 4-3-11 Pilot Responsibilities When Conducting Land and Hold Short Operations (LAHSO)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;6. A pilot who accepts a LAHSO clearance should land and exit the runway at the first convenient taxiway (unless directed otherwise) before reaching the hold short point. Otherwise, the pilot must stop and hold at the hold short point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is generally issued for smaller planes that don't need the full runway and a crossing runway/taxiway is also being used.&lt;/p&gt;&#xA;&lt;p&gt;As the pilot you have final say in accepting the clearance, if you feel you will be unable to hold short then you should reply &amp;quot;unable&amp;quot; and request full-length landing clearance.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[same link as above]&lt;/p&gt;&#xA;&lt;p&gt;3. The pilot-in-command has the final authority to accept or decline any land and hold short clearance. The safety and operation of the aircraft remain the responsibility of the pilot. Pilots are expected to decline a LAHSO clearance if they determine it will compromise safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-24T14:22:49.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3163" PostTypeId="5" CreationDate="2014-04-08T15:32:06.437" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-08T15:32:06.437" LastActivityDate="2014-04-08T15:32:06.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3164" PostTypeId="4" CreationDate="2014-04-08T15:32:06.437" Score="0" Body="The phase of flight in which an aircraft is lining up with the runway and preparing to land." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-08T15:47:35.880" LastActivityDate="2014-04-08T15:47:35.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3165" PostTypeId="5" CreationDate="2014-04-08T15:34:01.477" Score="0" Body="&lt;p&gt;&lt;strong&gt;Flight controls&lt;/strong&gt; are used to, as the name suggests, control an aircraft in &lt;a href=&quot;/questions/tagged/roll&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;roll&amp;#39;&quot; rel=&quot;tag&quot;&gt;roll&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/pitch&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pitch&amp;#39;&quot; rel=&quot;tag&quot;&gt;pitch&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/yaw&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;yaw&amp;#39;&quot; rel=&quot;tag&quot;&gt;yaw&lt;/a&gt;.  Part of what makes an &lt;a href=&quot;/questions/tagged/airplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;airplane&lt;/a&gt; an airplane (rather than another type of aircraft) is the ability to control its motions around each of its three &quot;principal axes&quot; (the roll axis, which passes longitudinally through the aircraft from nose to tail; the pitch axis, which passes horizontally through the aircraft from left to right; and the yaw axis, which passes vertically through the aircraft from top to bottom), rather than around only one or two of these axes.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Primary flight controls&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;These are the main flight controls used to control the plane during normal flight, usually taking the form of a set of &lt;a href=&quot;/questions/tagged/control-surfaces&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;control-surfaces&amp;#39;&quot; rel=&quot;tag&quot;&gt;control-surfaces&lt;/a&gt; mounted on various parts of the aircraft which deflect in response to the &lt;a href=&quot;/questions/tagged/pilots&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pilots&amp;#39;&quot; rel=&quot;tag&quot;&gt;pilots&lt;/a&gt;' control inputs.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/ailerons&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ailerons&amp;#39;&quot; rel=&quot;tag&quot;&gt;ailerons&lt;/a&gt;&lt;/em&gt; are mounted on outer portions of the &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s, and are used to roll the aircraft; the aileron(s) on one wing deflect downwards, and those on the other wing deflect upwards, raising the former wing and lowering the latter.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;em&gt;&lt;a href=&quot;/questions/tagged/flaperon&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flaperon&amp;#39;&quot; rel=&quot;tag&quot;&gt;flaperon&lt;/a&gt;&lt;/em&gt; is a dual-purpose surface, serving as an aileron at high speed and deflecting downwards to serve as a flap during &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/spoilers&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spoilers&amp;#39;&quot; rel=&quot;tag&quot;&gt;spoilers&lt;/a&gt;&lt;/em&gt; are used by some aircraft for roll control in addition to (or, occasionally, instead of) ailerons; to roll the aircraft, the spoiler(s) on one wing deploy, reducing the lift generated by that wing and causing the aircraft to roll towards the wing with the deployed spoilers.  A spoiler used for roll control is known as a &lt;em&gt;spoileron&lt;/em&gt; or &lt;em&gt;roll spoiler&lt;/em&gt;.  Spoilers are especially useful for roll control at both very low and very high &lt;a href=&quot;/questions/tagged/airspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspeed&lt;/a&gt;s, having less of an advantage in the middle of the speed range.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;&lt;a href=&quot;/questions/tagged/elevator&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;elevator&amp;#39;&quot; rel=&quot;tag&quot;&gt;elevator&lt;/a&gt;s&lt;/em&gt; provide pitch control; they are usually mounted on the trailing edge of the &lt;a href=&quot;/questions/tagged/horizontal-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;horizontal-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;horizontal-stabilizer&lt;/a&gt; in the &lt;a href=&quot;/questions/tagged/tail&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail&lt;/a&gt; section of the aircraft, but can also be mounted on the front portion of the aircraft (known as a &lt;a href=&quot;/questions/tagged/canard&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;canard&amp;#39;&quot; rel=&quot;tag&quot;&gt;canard&lt;/a&gt; configuration).  To pitch the aircraft up or down, the elevators on both sides of the aircraft deflect upwards or downwards, causing the tail (for conventional aircraft) or the nose (for canard aircraft) to rise or fall, and, thereby, pitching the aircraft in the desired direction.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In some aircraft (mainly those capable of &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; flight), the entire horizontal stabilizer &lt;em&gt;is&lt;/em&gt; the elevator; this is known as a &lt;em&gt;&lt;a href=&quot;/questions/tagged/stabilator&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stabilator&amp;#39;&quot; rel=&quot;tag&quot;&gt;stabilator&lt;/a&gt;&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/elevons&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;elevons&amp;#39;&quot; rel=&quot;tag&quot;&gt;elevons&lt;/a&gt;&lt;/em&gt; are used on most &lt;a href=&quot;/questions/tagged/delta-wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;delta-wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;delta-wing&lt;/a&gt; aircraft; as delta-winged aircraft usually do not have a separate horizontal tail, the control surfaces at the rear of the triangular wings do double duty as ailerons (they go up on one side and down on the other to roll the aircraft) and elevators (they either go up on both sides or go down on both sides, pitching the aircraft up or down).&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;&lt;a href=&quot;/questions/tagged/rudder&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rudder&amp;#39;&quot; rel=&quot;tag&quot;&gt;rudder&lt;/a&gt;&lt;/em&gt; is a vertical surface, almost always mounted on the tail, and usually attached to the trailing edge of the &lt;a href=&quot;/questions/tagged/vertical-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vertical-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;vertical-stabilizer&lt;/a&gt;; it deflects to the left or right to yaw the aircraft in the desired direction.&lt;/li&gt;&#xA;&lt;li&gt;A few aircraft have a &lt;a href=&quot;/questions/tagged/v-tail&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;v-tail&amp;#39;&quot; rel=&quot;tag&quot;&gt;v-tail&lt;/a&gt; configuration; these use &lt;em&gt;&lt;a href=&quot;/questions/tagged/ruddervator&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ruddervator&amp;#39;&quot; rel=&quot;tag&quot;&gt;ruddervator&lt;/a&gt;s&lt;/em&gt; mounted on the V-tail to provide both pitch and yaw control.  To pitch the aircraft up or down, both ruddervators deflect upwards-and-in or downwards-and-out; to yaw left or right, the ruddervator on one side deflects upwards-and-in, while the other deflects downwards-and-out.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Weight shifting&lt;/em&gt;, used by &lt;a href=&quot;/questions/tagged/hang-glider&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;hang-glider&amp;#39;&quot; rel=&quot;tag&quot;&gt;hang-glider&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/parachute&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;parachute&amp;#39;&quot; rel=&quot;tag&quot;&gt;parachute&lt;/a&gt; pilots, is exactly what it sounds like; the pilot shifts their position in (or, more usually, below) the aircraft, altering its &lt;a href=&quot;/questions/tagged/weight&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;weight&amp;#39;&quot; rel=&quot;tag&quot;&gt;weight&lt;/a&gt; distribution and causing it to roll or pitch in the desired direction.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/wing-warping&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing-warping&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing-warping&lt;/a&gt;&lt;/em&gt; was used in many early aircraft and still hangs on in higher-end &lt;a href=&quot;/questions/tagged/parachute&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;parachute&amp;#39;&quot; rel=&quot;tag&quot;&gt;parachute&lt;/a&gt;s; instead of using discrete control surfaces, the wings and stabilizers themselves are twisted manually in flight to change the aerodynamic forces acting on the aircraft, causing it to roll, pitch, or yaw in the desired direction.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Helicopter flight controls&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;/questions/tagged/helicopter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helicopter&amp;#39;&quot; rel=&quot;tag&quot;&gt;helicopter&lt;/a&gt; has a very different set of flight controls from an airplane:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;em&gt;collective&lt;/em&gt; adjusts the &lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt; of all of the helicopter's &lt;a href=&quot;/questions/tagged/main-rotor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;main-rotor&amp;#39;&quot; rel=&quot;tag&quot;&gt;main-rotor&lt;/a&gt; blades symmetrically, changing the amount of lift generated by the main rotor and causing the helicopter to climb or descend.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;cyclic&lt;/em&gt; increases the angle of attack of the rotor blades on one side of the main rotor disk and decreases the angle of attack of the blades on the other side, causing the helicopter to tilt towards the low-angle-of-attack side; this causes the lift from the main rotor to point slightly forward or backward or sideways rather than lifting straight up, and, thus, causes the helicopter to move horizontally through the air in the desired direction.&lt;/li&gt;&#xA;&lt;li&gt;The helicopter's &lt;em&gt;antitorque mechanism&lt;/em&gt; (usually a &lt;em&gt;&lt;a href=&quot;/questions/tagged/tail-rotor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail-rotor&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail-rotor&lt;/a&gt;&lt;/em&gt;) exerts a sideways force on the helicopter's tail to keep the main rotor's torque from making the helicopter spin like a top; the amount of force exerted by the antitorque mechanism can be varied slightly to yaw the helicopter to the left or right.  (Helicopters that use &lt;a href=&quot;/questions/tagged/tip-jets&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tip-jets&amp;#39;&quot; rel=&quot;tag&quot;&gt;tip-jets&lt;/a&gt; to drive the main rotor have no antitorque mechanism, and must use some other method to yaw the helicopter left or right.)&lt;/li&gt;&#xA;&lt;li&gt;Most helicopters also have a tail-mounted &lt;em&gt;rudder&lt;/em&gt;, and, sometimes, an &lt;em&gt;elevator&lt;/em&gt; as well, for use in forward flight, which function in the same manner as their counterparts on an airplane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Secondary/backup flight controls&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;These are not normally used to control the aircraft's motions directly, but can be used to roll, pitch, or yaw the aircraft if necessary (for instance, if the primary flight controls are malfunctioning or disabled).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/trim&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;trim&amp;#39;&quot; rel=&quot;tag&quot;&gt;trim&lt;/a&gt;&lt;/em&gt; systems, which work by moving small tabs mounted to the primary control surfaces (or, in the case of pitch trim on larger aircraft, by adjusting the &lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt; of the &lt;a href=&quot;/questions/tagged/horizontal-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;horizontal-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;horizontal-stabilizer&lt;/a&gt;), are usually used to aerodynamically &quot;balance&quot; the aircraft and reduce or null out the control forces needed to keep it in steady flight, but can be used as flight controls if the primary controls are out of commission (or, sometimes, if the required control authority is greater than what the primary controls can provide on their own).&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;&lt;a href=&quot;/questions/tagged/throttle&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;throttle&amp;#39;&quot; rel=&quot;tag&quot;&gt;throttle&lt;/a&gt;s&lt;/em&gt;, which control the amount of &lt;a href=&quot;/questions/tagged/thrust&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust&lt;/a&gt; generated by each individual &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt;, can be (and often have been) used for control if the primary flight controls are unavailable.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For pitch control, all the throttles are advanced or retarded symmetrically; advancing the throttles causes the airplane to accelerate and pitch up, while retarding the throttles causes it to decelerate and pitch down.  (This effect is most pronounced for airplanes with engines mounted under the wings, or someplace else similarly low down; if the engines are mounted high up on the airplane, as with most &lt;a href=&quot;/questions/tagged/regional-jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;regional-jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;regional-jet&lt;/a&gt; models and almost all &lt;a href=&quot;/questions/tagged/private-jets&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;private-jets&amp;#39;&quot; rel=&quot;tag&quot;&gt;private-jets&lt;/a&gt;, advancing the throttles will initially pitch the airplane &lt;em&gt;down&lt;/em&gt;, taking several seconds to accelerate enough to pitch back up, and vice versa.)&lt;/li&gt;&#xA;&lt;li&gt;For yaw and roll control, the throttles on one side are advanced, while those on the other side are retarded; the resulting thrust asymmetry will yaw the airplane towards the side with the throttles retarded, generating a &lt;a href=&quot;/questions/tagged/sideslip&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;sideslip&amp;#39;&quot; rel=&quot;tag&quot;&gt;sideslip&lt;/a&gt; which (for most airplane layouts) rolls the airplane towards the throttles-retarded wing.  Yawing and rolling an airplane in this manner is known as &lt;em&gt;throttle steering&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/flaps&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flaps&amp;#39;&quot; rel=&quot;tag&quot;&gt;flaps&lt;/a&gt;&lt;/em&gt; are usually used as &lt;a href=&quot;/questions/tagged/high-lift-device&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;high-lift-device&amp;#39;&quot; rel=&quot;tag&quot;&gt;high-lift-device&lt;/a&gt;s rather than as flight controls; however, extending the flaps changes the aircraft's pitching moment (usually causing it to pitch down, but occasionally &lt;em&gt;up&lt;/em&gt; instead; it depends on the specific type of aircraft), and can be used for some crude pitch control in an &lt;a href=&quot;/questions/tagged/emergency&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;emergency&amp;#39;&quot; rel=&quot;tag&quot;&gt;emergency&lt;/a&gt;.  Extending the flaps also usually increases the aircraft's inherent &lt;a href=&quot;/questions/tagged/stability&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stability&amp;#39;&quot; rel=&quot;tag&quot;&gt;stability&lt;/a&gt;, which is beneficial in many scenarios where the primary flight controls have been disabled.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/spoilers&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spoilers&amp;#39;&quot; rel=&quot;tag&quot;&gt;spoilers&lt;/a&gt;&lt;/em&gt; are usually used as high-drag devices (or sometimes for roll control; see far above), but they also change the aircraft's pitching moment when extended (usually creating a tendency to pitch up, although spoiler extension on a few types of aircraft actually causes them to pitch &lt;em&gt;down&lt;/em&gt;), and, thus, can be used to aid with crude pitch control (if whatever disabled the primary controls didn't also take out the spoilers).&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/landing-gear&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing-gear&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing-gear&lt;/a&gt;&lt;/em&gt; and (for aircraft so equipped) &lt;em&gt;&lt;a href=&quot;/questions/tagged/airbrakes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbrakes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbrakes&lt;/a&gt;&lt;/em&gt; increase the aircraft's &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt; when extended, causing it to slow down and pitch down; extending the landing gear also has a direct pitch-down effect (as the landing gear are lower down than the aircraft's &lt;a href=&quot;/questions/tagged/center-of-mass&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;center-of-mass&amp;#39;&quot; rel=&quot;tag&quot;&gt;center-of-mass&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The systems used to actuate an aircraft's flight controls vary in complexity and technology according to the aircraft's mission. Examples include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Mechanical linkages&lt;/em&gt; - Pushrods, pulleys, torsion bars, and other mechanical members are used to deflect control surfaces; used in all early aircraft, and small-to-midsize modern aircraft, as well as for &lt;a href=&quot;/questions/tagged/backup-systems&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;backup-systems&amp;#39;&quot; rel=&quot;tag&quot;&gt;backup-systems&lt;/a&gt; (something known as &lt;em&gt;manual reversion&lt;/em&gt;) in many larger aircraft in case hydraulic or electric linkages fail.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/servo-tabs&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;servo-tabs&amp;#39;&quot; rel=&quot;tag&quot;&gt;servo-tabs&lt;/a&gt;&lt;/em&gt; are used on many midsize and large aircraft; they alter the &lt;a href=&quot;/questions/tagged/aerodynamics&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aerodynamics&amp;#39;&quot; rel=&quot;tag&quot;&gt;aerodynamics&lt;/a&gt; of the control surfaces, creating a force that helps move the surfaces and reducing the amount of force that the pilots have to apply to the controls.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Hydraulic controls&lt;/em&gt; - The pilots' control inputs don't move the control surfaces directly, but, instead, actuate valves in the aircraft's &lt;a href=&quot;/questions/tagged/hydraulic-system&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;hydraulic-system&amp;#39;&quot; rel=&quot;tag&quot;&gt;hydraulic-system&lt;/a&gt;s, which then provide hydraulic force to move the desired surfaces.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;a href=&quot;/questions/tagged/fly-by-wire&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fly-by-wire&amp;#39;&quot; rel=&quot;tag&quot;&gt;fly-by-wire&lt;/a&gt;&lt;/em&gt; - Pilot input is translated into electrical signals, which are then sent to actuators that move the control surfaces; used primarily in large to very large transport aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Fly-by-light&lt;/em&gt; - Similar to fly-by-wire, but signals are sent via fiber-optic cables instead of electrical wires; not widely used (yet), but projected to have similar applications to fly-by-wire.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;No matter how the flight controls are actuated, there are almost always multiple ways to actuate any given control (for instance, duplicated control cables, or multiple hydraulic actuators driven by different hydraulic systems, or a hydraulic actuator for normal operation plus a mechanical linkage for manual-reversion operation, to give a few of the most common systems), in order to provide &lt;a href=&quot;/questions/tagged/redundancy&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;redundancy&amp;#39;&quot; rel=&quot;tag&quot;&gt;redundancy&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See Wikipedia for more information about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight controls in general, and airplane flight controls in particular&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Helicopter_flight_controls&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helicopter flight controls&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_mechanics&quot; rel=&quot;nofollow noreferrer&quot;&gt;The mechanics of flight, and how flight controls affect them&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_with_disabled_controls&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight with malfunctioning or inoperative primary flight controls&lt;/a&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Loss_of_control_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;The possible result of same&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="29740" LastEditorUserId="22726" LastEditDate="2019-09-30T06:26:23.830" LastActivityDate="2019-09-30T06:26:23.830" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3166" PostTypeId="4" CreationDate="2014-04-08T15:34:01.477" Score="0" Body="Use for cockpit controls (trim, yoke, etc). Use [control-surfaces] for the surfaces that actually move." OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2021-04-28T03:58:42.460" LastActivityDate="2021-04-28T03:58:42.460" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3167" PostTypeId="5" CreationDate="2014-04-08T15:35:10.563" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-08T15:35:10.563" LastActivityDate="2014-04-08T15:35:10.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3168" PostTypeId="4" CreationDate="2014-04-08T15:35:10.563" Score="0" Body="For questions on an airplane's main wing" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2021-04-19T19:21:29.207" LastActivityDate="2021-04-19T19:21:29.207" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3169" PostTypeId="5" CreationDate="2014-04-08T15:35:52.947" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-08T15:35:52.947" LastActivityDate="2014-04-08T15:35:52.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3170" PostTypeId="4" CreationDate="2014-04-08T15:35:52.947" Score="0" Body="Aircraft equipped with more than one engine." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-08T15:47:17.203" LastActivityDate="2014-04-08T15:47:17.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3171" PostTypeId="5" CreationDate="2014-04-08T15:37:18.213" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-08T15:37:18.213" LastActivityDate="2014-04-08T15:37:18.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3172" PostTypeId="4" CreationDate="2014-04-08T15:37:18.213" Score="0" Body="Conventional aircraft where the wings do not move to create lift. Distinct from rotary aircraft such as helicopters, where the lifting surfaces (rotors) spin to create lift." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-08T15:47:29.057" LastActivityDate="2014-04-08T15:47:29.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3173" PostTypeId="2" ParentId="3146" CreationDate="2014-04-08T15:39:04.743" Score="7" Body="&lt;p&gt;Please see the transcript of &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow&quot;&gt;Aeroflot 593&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overview: The pilot allowed his 12 year old and 16 year old children into the cockpit to sit in the pilot's seat of an Airbus A310. The older child's actions disconnected the autopilot. All aboard were killed when the crew was unable to recover from an unusual attitude after the autopilot disconnect. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Another possible passenger-caused accident is the death of Thomas J. Stewart and his family in a Eurocopter EC135 in Phoenix. Stewart allowed his 5 year old daughter to sit in his lap during the flight. The NTSB &lt;a href=&quot;http://www.nydailynews.com/news/national/5-year-old-sydney-stewart-caused-fatal-2010-helicopter-crash-kicked-controls-ntsb-article-1.1200227&quot; rel=&quot;nofollow&quot;&gt;concluded&lt;/a&gt; that the daughter kicked the controls and that the pilot's recovery attempt severed the tail. Both Stewart and his daughter were passengers and may have caused the accident with their actions. &lt;/p&gt;&#xA;" OwnerUserId="2072" LastEditorUserId="2072" LastEditDate="2015-03-31T22:44:57.757" LastActivityDate="2015-03-31T22:44:57.757" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3174" PostTypeId="2" ParentId="3146" CreationDate="2014-04-08T15:47:34.067" Score="7" Body="&lt;p&gt;There was a passenger who crashed an light aircraft over Bodensee in Austria. Psychological factors were assumed to be the reason the passenger forced the controls forward crashing the plane into the lake. He and the pilot were killed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://derstandard.at/1358303918284/Flugzeugabsturz-im-Bodensee-Passagier-brachte-Maschine-zum-Sturzflug&quot; rel=&quot;nofollow&quot;&gt;Der Standard&lt;/a&gt; (in German)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-01-02T00:29:45.000" LastActivityDate="2015-01-02T00:29:45.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3175" PostTypeId="2" ParentId="3109" CreationDate="2014-04-08T18:13:33.693" Score="2" Body="&lt;p&gt;From my checkride, I can say that the examiner strongly discouraged LAHSO operations in general.  That's not to say you &lt;strong&gt;can't&lt;/strong&gt; do it perhaps, but you probably &lt;strong&gt;shouldn't&lt;/strong&gt; do it (@Qantas 94 Heavy has a great analysis of the rules behind LAHSO, so no sense in repeating them).  Things to consider include making sure you have enough available landing distance and check against conditions with your aircraft performance data.  Remember, the examiner is testing, among other things, your decision making skills as a pilot.  Your examiner would probably be more impressed by declining a LAHSO clearance and landing safely with full-length than trying to show off to the examiner.  You already have to demonstrate a short and soft takeoff and landing -- probably not much sense in trying to go overboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, as a recently-certificated pilot with only about 60 hours of experience, I'd still decline a LAHSO clearance if given one.  There's nothing that says you need to take one, especially if you feel it may compromise your safety.&lt;/p&gt;&#xA;" OwnerUserId="2074" LastActivityDate="2014-04-08T18:13:33.693" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3176" PostTypeId="5" CreationDate="2014-04-09T00:02:57.280" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:02:57.280" LastActivityDate="2014-04-09T00:02:57.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3177" PostTypeId="4" CreationDate="2014-04-09T00:02:57.280" Score="0" Body="The process of driving an aircraft on the ground, e.g. from the gate to the runway." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:01:05.150" LastActivityDate="2014-04-09T01:01:05.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3178" PostTypeId="5" CreationDate="2014-04-09T00:03:43.463" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:03:43.463" LastActivityDate="2014-04-09T00:03:43.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3179" PostTypeId="4" CreationDate="2014-04-09T00:03:43.463" Score="0" Body="A controlled parachute jump out of an aircraft for sport." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-06-04T10:15:22.970" LastActivityDate="2019-06-04T10:15:22.970" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3180" PostTypeId="5" CreationDate="2014-04-09T00:04:48.610" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:04:48.610" LastActivityDate="2014-04-09T00:04:48.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3181" PostTypeId="4" CreationDate="2014-04-09T00:04:48.610" Score="0" Body="An airport that is not controlled by airport-based air traffic control" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:48:32.767" LastActivityDate="2014-04-09T01:48:32.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3182" PostTypeId="5" CreationDate="2014-04-09T00:05:34.210" Score="0" Body="&lt;p&gt;Flight attendants or cabin crew (also known as stewards/stewardesses, air hosts/hostesses, cabin attendants) are members of an aircrew employed by airlines primarily to ensure the safety and comfort of passengers aboard commercial flights, on select business jet aircraft, and on some military aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary role of a flight attendant is to ensure passenger safety. In addition to this, flight attendants are often tasked with customer service duties such as serving meals and drinks, as a secondary responsibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number of flight attendants required on flights are mandated by international safety regulations. For planes with up to 19 passenger seats, no flight attendant is needed. For larger planes, one flight attendant per 50 passenger seats is needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The majority of flight attendants for most airlines are female, though a substantial number of males have entered the industry since the 1970s.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:08:24.723" LastActivityDate="2015-06-23T11:08:24.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3183" PostTypeId="4" CreationDate="2014-04-09T00:05:34.210" Score="0" Body="Flight attendants or cabin crew (also known as stewards/stewardesses, air hosts/hostesses, cabin attendants) are members of an aircrew employed by airlines primarily to ensure the safety and comfort of passengers aboard commercial flights, on select business jet aircraft, and on some military aircraft." OwnerUserId="97" LastEditorUserId="8547" LastEditDate="2015-06-23T09:51:20.793" LastActivityDate="2015-06-23T09:51:20.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3184" PostTypeId="5" CreationDate="2014-04-09T00:06:06.807" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:06:06.807" LastActivityDate="2014-04-09T00:06:06.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3185" PostTypeId="4" CreationDate="2014-04-09T00:06:06.807" Score="0" Body="Certified Flight Instructor, allowed to provide flight instruction for other pilots." OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2015-04-17T02:42:05.997" LastActivityDate="2015-04-17T02:42:05.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3186" PostTypeId="5" CreationDate="2014-04-09T00:07:23.633" Score="0" Body="&lt;p&gt;Use this tag for questions about how to become employed as an aviation professional. This includes subjects like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How to pay for training, e.g. training grants&lt;/li&gt;&#xA;&lt;li&gt;Qualifications, e.g. whether a degree is required or not&lt;/li&gt;&#xA;&lt;li&gt;Employment regulations and practices, e.g. seniority, rest hours, crew travel perks&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's a large potential overlap with other aviation topics like flight training and also with non-aviation topics like education or employment law. So please keep your questions focused on things that are unique to &lt;em&gt;working&lt;/em&gt; as an aviation professional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions about the training and tests required for a commercial pilot's license should usually be tagged &lt;a href=&quot;/questions/tagged/airman-certification&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airman-certification&amp;#39;&quot; rel=&quot;tag&quot;&gt;airman-certification&lt;/a&gt; as well.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="62" LastEditDate="2017-04-24T13:36:44.373" LastActivityDate="2017-04-24T13:36:44.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3187" PostTypeId="4" CreationDate="2014-04-09T00:07:23.633" Score="0" Body="For questions about becoming, or working as, an aviation professional: pilot, controller, mechanic etc." OwnerUserId="97" LastEditorUserId="62" LastEditDate="2017-04-24T13:36:44.373" LastActivityDate="2017-04-24T13:36:44.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3188" PostTypeId="5" CreationDate="2014-04-09T00:08:06.813" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:08:06.813" LastActivityDate="2014-04-09T00:08:06.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3189" PostTypeId="4" CreationDate="2014-04-09T00:08:06.813" Score="0" Body="For questions specifically relating to Australia" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:00:28.130" LastActivityDate="2014-04-09T01:00:28.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3190" PostTypeId="5" CreationDate="2014-04-09T00:09:25.247" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:09:25.247" LastActivityDate="2014-04-09T00:09:25.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3191" PostTypeId="4" CreationDate="2014-04-09T00:09:25.247" Score="0" Body="A heading is a compass direction, given in degrees (0-359°). It refers to the direction the nose of the aircraft is pointing, which may be different from the direction the aircraft is traveling (called a track). Use this tag for questions relating to the usage of the term heading, but should not be used for general navigation or ATC related questions." OwnerUserId="97" LastEditorUserId="6" LastEditDate="2014-04-11T03:07:23.857" LastActivityDate="2014-04-11T03:07:23.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3192" PostTypeId="5" CreationDate="2014-04-09T00:10:09.577" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:10:09.577" LastActivityDate="2014-04-09T00:10:09.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3193" PostTypeId="4" CreationDate="2014-04-09T00:10:09.577" Score="0" Body="A company teaching student pilots to fly" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:17:11.137" LastActivityDate="2014-04-09T01:17:11.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3194" PostTypeId="5" CreationDate="2014-04-09T00:11:33.820" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:11:33.820" LastActivityDate="2014-04-09T00:11:33.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3195" PostTypeId="4" CreationDate="2014-04-09T00:11:33.820" Score="0" Body="A pressure-based system for measuring airspeed and altitude." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-11-22T03:00:42.437" LastActivityDate="2019-11-22T03:00:42.437" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3196" PostTypeId="5" CreationDate="2014-04-09T00:12:57.247" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:12:57.247" LastActivityDate="2014-04-09T00:12:57.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3197" PostTypeId="4" CreationDate="2014-04-09T00:12:57.247" Score="0" Body="Altitudes above the transition altitude, where the altimeter is set to the standard pressure, and is expressed as the letters &quot;FL&quot; followed by the indicated altitude in hundreds of feet, e.g., FL380." OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2015-04-17T02:46:09.393" LastActivityDate="2015-04-17T02:46:09.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3198" PostTypeId="5" CreationDate="2014-04-09T00:14:11.143" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:14:11.143" LastActivityDate="2014-04-09T00:14:11.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3199" PostTypeId="4" CreationDate="2014-04-09T00:14:11.143" Score="0" Body="Attitude is the orientation of an aircraft during flight.  Normal attitude of an aircraft is wings-level, neutral pitch, and nose pointed in the direction of flight." OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-18T06:11:12.400" LastActivityDate="2015-05-18T06:11:12.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3200" PostTypeId="5" CreationDate="2014-04-09T00:14:39.197" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:14:39.197" LastActivityDate="2014-04-09T00:14:39.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3201" PostTypeId="4" CreationDate="2014-04-09T00:14:39.197" Score="0" Body="A company which designs or manufactures aircraft and/or aircraft parts" OwnerUserId="97" LastEditorUserId="6919" LastEditDate="2015-05-18T04:34:45.860" LastActivityDate="2015-05-18T04:34:45.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3202" PostTypeId="5" CreationDate="2014-04-09T00:17:47.487" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:17:47.487" LastActivityDate="2014-04-09T00:17:47.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3203" PostTypeId="4" CreationDate="2014-04-09T00:17:47.487" Score="0" Body="A unique registration number (or &quot;tail-number&quot;) for an aircraft - similar to a car's license plate." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:22:56.823" LastActivityDate="2014-04-09T01:22:56.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3204" PostTypeId="5" CreationDate="2014-04-09T00:18:15.593" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:18:15.593" LastActivityDate="2014-04-09T00:18:15.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3205" PostTypeId="4" CreationDate="2014-04-09T00:18:15.593" Score="0" Body="For questions related to Canada. Use [transport-canada] for questions about regulations in Canada." OwnerUserId="97" LastEditorUserId="14897" LastEditDate="2019-08-29T14:17:53.477" LastActivityDate="2019-08-29T14:17:53.477" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3206" PostTypeId="5" CreationDate="2014-04-09T00:18:29.730" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:18:29.730" LastActivityDate="2014-04-09T00:18:29.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3207" PostTypeId="4" CreationDate="2014-04-09T00:18:29.730" Score="0" Body="For questions specifically related to France" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:01:32.070" LastActivityDate="2014-04-09T01:01:32.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3208" PostTypeId="5" CreationDate="2014-04-09T00:18:58.943" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:18:58.943" LastActivityDate="2014-04-09T00:18:58.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3209" PostTypeId="4" CreationDate="2014-04-09T00:18:58.943" Score="0" Body="For questions specifically related to the United Kingdom" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:01:34.977" LastActivityDate="2014-04-09T01:01:34.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3210" PostTypeId="5" CreationDate="2014-04-09T00:19:51.977" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:19:51.977" LastActivityDate="2014-04-09T00:19:51.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3211" PostTypeId="4" CreationDate="2014-04-09T00:19:51.977" Score="0" Body="For questions specifically related to India" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:23:26.003" LastActivityDate="2014-04-09T01:23:26.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3212" PostTypeId="5" CreationDate="2014-04-09T00:20:02.297" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:20:02.297" LastActivityDate="2014-04-09T00:20:02.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3213" PostTypeId="4" CreationDate="2014-04-09T00:20:02.297" Score="0" Body="For questions specifically related to Germany" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T00:57:23.227" LastActivityDate="2014-04-09T00:57:23.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3214" PostTypeId="5" CreationDate="2014-04-09T00:21:39.473" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:21:39.473" LastActivityDate="2014-04-09T00:21:39.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3215" PostTypeId="4" CreationDate="2014-04-09T00:21:39.473" Score="0" Body="For questions regarding the aeronautical work of NASA. Questions focused on the space aspects should be asked on the Space Exploration site." OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2020-05-27T21:03:51.230" LastActivityDate="2020-05-27T21:03:51.230" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3216" PostTypeId="5" CreationDate="2014-04-09T00:23:08.593" Score="0" Body="&lt;p&gt;Aviation medicine covers many different aspects of health and human performance. There are two broad areas that are suitable topics for questions on this site: medical certification and general physiological or psychological considerations in aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots usually require a medical certificate in order to fly legally, although there may be exceptions for some light aircraft. The purpose of pilot medical certification is to confirm that the pilot has a basic level of physical ability needed for flying (eyesight, hearing, balance), and to ensure that there are no chronic (long-term) conditions that might cause sudden or temporary incapacitation during flight (e.g. heart disease, epilepsy, some medications).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many countries have different levels or classes of medical certification, with higher levels being required for airline pilots and lower levels for private pilots. In some countries pilots may fly without an aviation medical certificate in certain conditions or aircraft types, such as the sport pilot certification in the US. All pilots are expected to use their own judgement and not fly if they feel unwell or unable to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from the actual certification process, there are many physiological and psychological issues that can affect pilots. Even a perfectly healthy pilot may experience visual illusions or false sensations of movement during flight (especially instrument flight) or suffer - perhaps unknowingly - from the effects of hypoxia in an unpressurized aircraft at a higher altitude. Night vision is also affected significantly by lack of oxygen. Stress, tiredness or medications can affect reaction times, decision making and judgement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag can be used for any questions about aviation medical certification, general medical issues and physical or psychological issues, if they relate directly to aviation.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/pilots/medical/&quot; rel=&quot;nofollow&quot;&gt;FAA Medical Certification&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aviation_medicine&quot; rel=&quot;nofollow&quot;&gt;Aviation medicine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Sensory_illusions_in_aviation&quot; rel=&quot;nofollow&quot;&gt;Sensory illusions in aviation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-09T15:17:03.223" LastActivityDate="2015-11-09T15:17:03.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3217" PostTypeId="4" CreationDate="2014-04-09T00:23:08.593" Score="0" Body="Use for medical certification and aviation-related physiological and psychological factors; use [medevac] for medical evacuation aircraft and their procedures." OwnerUserId="97" LastEditorUserId="14897" LastEditDate="2020-03-27T13:46:39.980" LastActivityDate="2020-03-27T13:46:39.980" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3218" PostTypeId="5" CreationDate="2014-04-09T00:25:21.013" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:25:21.013" LastActivityDate="2014-04-09T00:25:21.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3219" PostTypeId="4" CreationDate="2014-04-09T00:25:21.013" Score="0" Body="For questions specifically pertaining to pilots themselves, rather than aircraft or flying; use [career] instead where applicable." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:26:11.657" LastActivityDate="2014-04-09T01:26:11.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3220" PostTypeId="5" CreationDate="2014-04-09T00:26:56.473" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:26:56.473" LastActivityDate="2014-04-09T00:26:56.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3221" PostTypeId="4" CreationDate="2014-04-09T00:26:56.473" Score="0" Body="The staff on-board an airplane, including pilots and flight attendants." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T06:12:40.020" LastActivityDate="2014-04-09T06:12:40.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3222" PostTypeId="5" CreationDate="2014-04-09T00:27:44.337" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:27:44.337" LastActivityDate="2014-04-09T00:27:44.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3223" PostTypeId="4" CreationDate="2014-04-09T00:27:44.337" Score="0" Body="Frozen water particles that are potentially dangerous to flights" OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2018-04-06T19:37:47.277" LastActivityDate="2018-04-06T19:37:47.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3224" PostTypeId="5" CreationDate="2014-04-09T00:28:51.123" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:28:51.123" LastActivityDate="2014-04-09T00:28:51.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3225" PostTypeId="4" CreationDate="2014-04-09T00:28:51.123" Score="0" Body="The permission from air traffic control to take an action, e.g. to land on runway 5." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:02:19.013" LastActivityDate="2014-04-09T01:02:19.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3226" PostTypeId="5" CreationDate="2014-04-09T00:30:21.873" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:30:21.873" LastActivityDate="2014-04-09T00:30:21.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3227" PostTypeId="4" CreationDate="2014-04-09T00:30:21.873" Score="0" Body="Turbulence that forms behind an aircraft, which is particularly dangerous during takeoff and landing." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T00:49:14.330" LastActivityDate="2014-04-09T00:49:14.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3228" PostTypeId="5" CreationDate="2014-04-09T00:31:23.673" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:31:23.673" LastActivityDate="2014-04-09T00:31:23.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3229" PostTypeId="4" CreationDate="2014-04-09T00:31:23.673" Score="0" Body="Large cavities that store fuel, typically in the wings and/or belly of the plane." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:08:09.650" LastActivityDate="2014-04-09T01:08:09.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3230" PostTypeId="5" CreationDate="2014-04-09T00:33:28.727" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:33:28.727" LastActivityDate="2014-04-09T00:33:28.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3231" PostTypeId="4" CreationDate="2014-04-09T00:33:28.727" Score="0" Body="A type of uncontrolled divergent oscillations in an aircraft's structure, typically encountered at excessively-high speeds or if the airframe's stiffness has been reduced by previous damage.  Flutter is extremely dangerous, and can rapidly cause an aircraft to break apart in flight; it has caused many fatal accidents over the years." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-10-06T11:02:52.587" LastActivityDate="2019-10-06T11:02:52.587" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3232" PostTypeId="5" CreationDate="2014-04-09T00:35:10.083" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:35:10.083" LastActivityDate="2014-04-09T00:35:10.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3233" PostTypeId="4" CreationDate="2014-04-09T00:35:10.083" Score="0" Body="A manoeuvre where full power is applied in order to climb, during an aborted landing." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:19:51.083" LastActivityDate="2014-04-09T01:19:51.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3234" PostTypeId="5" CreationDate="2014-04-09T00:35:42.440" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:35:42.440" LastActivityDate="2014-04-09T00:35:42.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3235" PostTypeId="4" CreationDate="2014-04-09T00:35:42.440" Score="0" Body="Questions about airport or aircraft fires/firefighting, including engine and cabin fire suppression systems and equipment, in-flight fire procedures, and ground firefighting procedures." OwnerUserId="-1" LastEditorUserId="64" LastEditDate="2014-04-09T05:22:42.340" LastActivityDate="2014-04-09T05:22:42.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3236" PostTypeId="5" CreationDate="2014-04-09T00:36:40.143" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:36:40.143" LastActivityDate="2014-04-09T00:36:40.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3237" PostTypeId="4" CreationDate="2014-04-09T00:36:40.143" Score="0" Body="Use on questions about how airport lighting is used, installed or operated. Airport lighting includes runway and taxiway lights, approach lighting, airport beacons, etc." OwnerUserId="97" LastEditorUserId="6" LastEditDate="2014-04-09T01:42:21.767" LastActivityDate="2014-04-09T01:42:21.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3238" PostTypeId="5" CreationDate="2014-04-09T00:38:00.000" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:38:00.000" LastActivityDate="2014-04-09T00:38:00.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3239" PostTypeId="4" CreationDate="2014-04-09T00:38:00.000" Score="0" Body="For questions specifically related to the EU, but not specifically to a member nation" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T00:58:04.437" LastActivityDate="2014-04-09T00:58:04.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3240" PostTypeId="5" CreationDate="2014-04-09T00:38:33.607" Score="0" Body="&lt;p&gt;&lt;em&gt;Transatlantic&lt;/em&gt; flights are flights which cross the Atlantic Ocean; in common usage, the term refers to flights crossing the &lt;em&gt;North&lt;/em&gt; Atlantic (flying between North America and Europe), although flights across the South Atlantic (between South America and Africa) are also &quot;transatlantic&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first transatlantic flight was in May 1919, when a U.S. Navy Curtiss NC-4 flew from New York to England with stops in Newfoundland, the Azores, and Portugal.  The first &lt;em&gt;commercial&lt;/em&gt; transatlantic flight was made by the &lt;a href=&quot;/questions/tagged/airship&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airship&amp;#39;&quot; rel=&quot;tag&quot;&gt;airship&lt;/a&gt; &lt;em&gt;Graf Zeppelin&lt;/em&gt; (LZ127) in 1928; the first commercial transatlantic flight in a heavier-than-air aircraft was an airmail flight between Germany and Brazil by &lt;a href=&quot;/questions/tagged/lufthansa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lufthansa&amp;#39;&quot; rel=&quot;tag&quot;&gt;lufthansa&lt;/a&gt; in February 1934, while the first heavier-than-air commercial passenger flights were between North America and Europe in 1937.  The first scheduled transatlantic passenger flight by a &lt;a href=&quot;/questions/tagged/jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet&lt;/a&gt;, between London and New York with a refueling stop in Gander, Newfoundland, was made by BOAC on 4 October 1958 using a &lt;a href=&quot;/questions/tagged/de-havilland-comet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;de-havilland-comet&amp;#39;&quot; rel=&quot;tag&quot;&gt;de-havilland-comet&lt;/a&gt;, and jetliners quickly took over the transatlantic airline market.  Originally, only jets with three or more engines (such as the Comet, &lt;a href=&quot;/questions/tagged/boeing-707&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-707&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-707&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/dc-8&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-8&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-8&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/dc-10&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-10&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-10&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/lockheed-tristar&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lockheed-tristar&amp;#39;&quot; rel=&quot;tag&quot;&gt;lockheed-tristar&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/md-11&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;md-11&amp;#39;&quot; rel=&quot;tag&quot;&gt;md-11&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/airbus-a380&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a380&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a380&lt;/a&gt;) were allowed to make transatlantic crossings; however, since the introduction of &lt;a href=&quot;/questions/tagged/etops&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;etops&amp;#39;&quot; rel=&quot;tag&quot;&gt;etops&lt;/a&gt;, airlines have mostly switched to using twinjets (such as the &lt;a href=&quot;/questions/tagged/airbus-a300&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a300&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a300&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-767&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-767&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-767&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-757&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-757&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-757&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/airbus-a310&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a310&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a310&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/airbus-a330&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a330&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a330&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/airbus-a350&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a350&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a350&lt;/a&gt;, plus, to a much lesser extent, the &lt;a href=&quot;/questions/tagged/boeing-737&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-737&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-737&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/airbus-a320&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a320&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a320&lt;/a&gt;), which are cheaper and more efficient.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2018-12-31T02:22:10.220" LastActivityDate="2018-12-31T02:22:10.220" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3241" PostTypeId="4" CreationDate="2014-04-09T00:38:33.607" Score="0" Body="Flights that cross the Atlantic Ocean, either with or without stopping en route." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2018-12-31T02:22:15.820" LastActivityDate="2018-12-31T02:22:15.820" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3242" PostTypeId="5" CreationDate="2014-04-09T00:39:09.380" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:39:09.380" LastActivityDate="2014-04-09T00:39:09.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3243" PostTypeId="4" CreationDate="2014-04-09T00:39:09.380" Score="0" Body="The rate of altitude change, measured in positive and negative feet per minute." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:01:22.543" LastActivityDate="2014-04-09T01:01:22.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3244" PostTypeId="5" CreationDate="2014-04-09T00:39:37.493" Score="0" Body="&lt;p&gt;A &lt;strong&gt;seaplane&lt;/strong&gt; is an airplane designed to make &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt;s on bodies of water, rather than needing to use conventional &lt;a href=&quot;/questions/tagged/runways&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runways&amp;#39;&quot; rel=&quot;tag&quot;&gt;runways&lt;/a&gt;.  Contrary to what the name implies, the body of water does not &lt;em&gt;have&lt;/em&gt; to be the sea (although it often is), but can be any body of water of sufficient size; many lakes (especially in places with a lot of lakes and not a lot of fixed infrastructure, like Alaska, Siberia, or northern Canada) and sufficiently-whitewater-free rivers are frequented by seaplanes, and a few airports on land have dedicated &lt;em&gt;water runways&lt;/em&gt; (long, runway-size trenches dug in the ground and filled with water) to allow seaplanes to operate to and from them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two main types of seaplanes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Floatplanes&lt;/strong&gt; are mostly shaped like a regular aircraft, but have large floats mounted under the sides of the &lt;a href=&quot;/questions/tagged/fuselage&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuselage&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuselage&lt;/a&gt; and/or extending downward from the &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s (some floatplanes have additional &quot;stub wings&quot; - mounted lower down on the fuselage than the main wings - whose main purpose is to carry floats); when on the water, the floats float on the water, and the airplane sits on top of them.  Most smaller airplanes can be retrofitted with floats with a bit of hangarwork and paperwork, but larger airplanes would require prohibitively-long, -heavy, and -draggy floats to keep them from tipping over on the water.&lt;/li&gt;&#xA;&lt;li&gt;Instead of using external floats, a &lt;strong&gt;flying boat&lt;/strong&gt; uses the airplane's entire fuselage as one giant float; as the name indicates, a flying boat has a boat-hulled fuselage which rests in the water when not airborne.  Flying boats can be made very large; before World War II, all of the largest and longest-range &lt;a href=&quot;/questions/tagged/airliner&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airliner&amp;#39;&quot; rel=&quot;tag&quot;&gt;airliner&lt;/a&gt;s were flying boats, as land-based &lt;a href=&quot;/questions/tagged/airport&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airport&amp;#39;&quot; rel=&quot;tag&quot;&gt;airport&lt;/a&gt;s with long enough runways for a large airplane were rarities, whereas nearly any harbour city could accommodate a flying boat (the fact that a midocean &lt;a href=&quot;/questions/tagged/forced-landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;forced-landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;forced-landing&lt;/a&gt; in a flying boat is considerably more survivable than attempting a &lt;a href=&quot;/questions/tagged/ditching&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ditching&amp;#39;&quot; rel=&quot;tag&quot;&gt;ditching&lt;/a&gt; in a landplane can't have hurt).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Either type can also be made as an &lt;em&gt;amphibious&lt;/em&gt; (or &lt;em&gt;amphibian&lt;/em&gt;) airplane, with retractable &lt;a href=&quot;/questions/tagged/landing-gear&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing-gear&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing-gear&lt;/a&gt; extending from the floats of a floatplane or the hull of a flying boat; this allows the airplane to take off and/or land from a land-based airport if necessary and/or desired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both types of seaplane suffer from increased &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt; - a floatplane due to its large floats hanging around in the airstream, and a flying boat because of the big fat boat hull which is shaped to keep the airplane afloat and stable in the water, and not so much to be streamlined and efficient in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see Wikipedia's articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Seaplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;Seaplanes in general&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Amphibious_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Amphibious airplanes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Floatplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;Floatplanes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flying_boat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flying boats&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-10-10T03:14:32.493" LastActivityDate="2019-10-10T03:14:32.493" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3245" PostTypeId="4" CreationDate="2014-04-09T00:39:37.493" Score="0" Body="An airplane designed to take off and land on water. This include floatplanes and flying boats." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2019-05-30T10:34:03.303" LastActivityDate="2019-05-30T10:34:03.303" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3246" PostTypeId="5" CreationDate="2014-04-09T00:41:45.480" Score="0" Body="&lt;p&gt;Flight simulators are devices that replicate aircraft flight and the flight environment. Emphasis is placed on replicating the cockpit controls and displays for training purposes. Most simulators also replicate the flight environment through visual displays, audio, and even motion. Simulators are especially helpful in enabling training that is not possible in-flight, e.g. emergencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term simulator can be used to refer to devices including Home PC based devices, Flight Training Devices, and motion Simulators.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="12720" LastEditDate="2016-04-09T17:49:01.230" LastActivityDate="2016-04-09T17:49:01.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3247" PostTypeId="4" CreationDate="2014-04-09T00:41:45.480" Score="0" Body="A ground-based machine which replicates aspects of aircraft flight and is used for flight training." OwnerUserId="97" LastEditorUserId="12720" LastEditDate="2016-04-09T17:49:01.230" LastActivityDate="2016-04-09T17:49:01.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3248" PostTypeId="5" CreationDate="2014-04-09T00:42:52.193" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:42:52.193" LastActivityDate="2014-04-09T00:42:52.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3249" PostTypeId="4" CreationDate="2014-04-09T00:42:52.193" Score="0" Body="Columns of rising air that are formed on the ground through the warming of the surface by sunlight, used by gliders to gain altitude" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:16:16.700" LastActivityDate="2014-04-09T01:16:16.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3250" PostTypeId="5" CreationDate="2014-04-09T00:43:26.937" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:43:26.937" LastActivityDate="2014-04-09T00:43:26.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3251" PostTypeId="4" CreationDate="2014-04-09T00:43:26.937" Score="0" Body="San Francisco International Airport" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T00:57:50.000" LastActivityDate="2014-04-09T00:57:50.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3252" PostTypeId="5" CreationDate="2014-04-09T00:43:48.557" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:43:48.557" LastActivityDate="2014-04-09T00:43:48.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3253" PostTypeId="4" CreationDate="2014-04-09T00:43:48.557" Score="0" Body="Levers in the cockpit that control engine thrust" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:13:49.753" LastActivityDate="2014-04-09T01:13:49.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3254" PostTypeId="5" CreationDate="2014-04-09T00:44:34.897" Score="0" Body="&lt;p&gt;&lt;em&gt;Stealth&lt;/em&gt; refers to the technologies used for making military aircraft harder to detect, mainly by making them less visible to &lt;a href=&quot;/questions/tagged/radar&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radar&amp;#39;&quot; rel=&quot;tag&quot;&gt;radar&lt;/a&gt;; as radar is the primary means of detecting attacking aircraft, making a fighter or bomber harder to pick up on radar gives it a better chance of surviving a mission or missions without getting shot down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several different ways of making aircraft stealthier:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most stealth aircraft are carefully shaped so that, if radio waves emitted by an enemy radar strike the aircraft, very little of the signal is reflected back towards the radar installation; most of the radio waves bounce off in other directions.  To achieve this, some early stealth aircraft (such as the F-117 &quot;Nighthawk&quot;) had a very angular, faceted appearance; advances in the software used to find stealthy shapes have enabled newer stealth aircraft to have smoother, more aerodynamic shapes.&lt;/li&gt;&#xA;&lt;li&gt;Stealth aircraft have to take great care to avoid maneuvers that would present large flat surfaces to an enemy radar, as this would greatly increase the aircraft's visibility to said radar.&lt;/li&gt;&#xA;&lt;li&gt;Some aircraft are painted with materials that absorb radio waves rather than reflecting them; the compositions of these materials are generally tightly classified, but are thought to often contain microscopic spheres of substances such as iron or carbon black.&lt;/li&gt;&#xA;&lt;li&gt;Stealth aircraft generally lack large protrusions, as these tend to be good radar reflectors; instead of carrying bombs and missiles on external hardpoints, stealth fighters and bombers carry all of their munitions in an internal bomb bay.&lt;/li&gt;&#xA;&lt;li&gt;To prevent passive radar receivers from picking up the aircraft's own radio transmissions (and thereby possibly allowing enemy forces to determine its position and movement), stealth aircraft use special radars that send out pulses of radio waves at irregular intervals at random frequencies and intensities, rather than regular strong pulses on a single frequency, and generally maintain strict radio silence in combat zones except in dire emergency.&lt;/li&gt;&#xA;&lt;li&gt;Other aspects of stealth include reducing or disguising infrared emissions from an aircraft's engines (thus making it harder to target with &lt;a href=&quot;/questions/tagged/heat-seeking-missiles&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;heat-seeking-missiles&amp;#39;&quot; rel=&quot;tag&quot;&gt;heat-seeking-missiles&lt;/a&gt;), painting it dark colours and operating at night to make it less visible to the naked eye, and using quieter engines and avoiding &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; flight so as to make it harder to hear it coming.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2018-08-09T06:00:43.813" LastActivityDate="2018-08-09T06:00:43.813" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3255" PostTypeId="4" CreationDate="2014-04-09T00:44:34.897" Score="0" Body="A set of techniques used by some military aircraft to avoid being detected by enemy air defences." OwnerUserId="97" LastEditorUserId="22726" LastEditDate="2018-08-09T06:00:29.623" LastActivityDate="2018-08-09T06:00:29.623" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3256" PostTypeId="5" CreationDate="2014-04-09T00:47:49.123" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:47:49.123" LastActivityDate="2014-04-09T00:47:49.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3257" PostTypeId="4" CreationDate="2014-04-09T00:47:49.123" Score="0" Body="The prefiled planned route between departure and arrival airports" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T01:16:38.493" LastActivityDate="2014-04-09T01:16:38.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3258" PostTypeId="5" CreationDate="2014-04-09T00:49:35.153" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T00:49:35.153" LastActivityDate="2014-04-09T00:49:35.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3259" PostTypeId="4" CreationDate="2014-04-09T00:49:35.153" Score="0" Body="A marker on the PFD or MFD indicating the proposed attitude the autopilot will fly." OwnerUserId="97" LastEditorUserId="595" LastEditDate="2017-07-02T06:48:48.990" LastActivityDate="2017-07-02T06:48:48.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3260" PostTypeId="2" ParentId="177" CreationDate="2014-04-09T01:19:56.287" Score="9" Body="&lt;p&gt;This is handled on jurisdiction by jurisdiction basis. While sea plane &quot;bases&quot; are marked on the sectional, this only means that the location has been registered with the FAA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air space over the water is handled federally. The water itself is handled locally. When the aircraft is on the water, it is generally considered a boat under the law, except where a jurisdiction has chosen to single out sea planes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately many jurisdictions have done just that. Any little mud puddle can potentially be banned for sea plane operations by the local community. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an association of sea plane pilots who involve themselves in advocacy to keep waters available. They publish some useful materials on this subject. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you plan on going for your sea plane endorsement, your instructor will give you the pertinent details. If you would like to fly locally, you will need to check out your local codes. If operations have not yet been banned, it would be sensible to join the association, and take an active role in keeping local waters open to sea planes in your area.&lt;/p&gt;&#xA;" OwnerUserId="2078" LastActivityDate="2014-04-09T01:19:56.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3261" PostTypeId="1" AcceptedAnswerId="3277" CreationDate="2014-04-09T01:55:19.660" Score="6" ViewCount="1274" Body="&lt;p&gt;I'm wondering if there's ground radar on planes, or any fallback system other than relying on a controller, for avoiding runway incursions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have any studies or reports been made that show statistically how the majority of these incidents occur?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/W98Ar.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="72" LastEditDate="2014-04-09T03:41:31.643" LastActivityDate="2014-04-15T11:10:30.920" Title="How are runway incursions avoided?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;runways&gt;&lt;radar&gt;&lt;runway-incursion&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3262" PostTypeId="5" CreationDate="2014-04-09T01:58:17.320" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T01:58:17.320" LastActivityDate="2014-04-09T01:58:17.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3263" PostTypeId="4" CreationDate="2014-04-09T01:58:17.320" Score="0" Body="Any occurrence at an aerodrome involving the unauthorized presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and take off of aircraft" OwnerUserId="97" LastEditorUserId="15637" LastEditDate="2019-02-22T18:22:30.917" LastActivityDate="2019-02-22T18:22:30.917" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3264" PostTypeId="1" AcceptedAnswerId="3280" CreationDate="2014-04-09T02:13:15.270" Score="33" ViewCount="30838" Body="&lt;p&gt;I recall that in the UK (unlike in the rest of the world) we have a law forbidding the listening to of air traffic control, dating back a century, to the days of paranoia over spies!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this law, exactly? Is it illegal for a member of the public to listen to live ATC in the UK? Are there any exceptions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like something of a grey area, but some sources claim that listening to a delayed feed (or historical recording) works around this law; is this true?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-07-04T16:15:39.470" LastActivityDate="2020-05-28T18:16:11.430" Title="Is it illegal for Joe Public to listen to ATC in the UK?" Tags="&lt;air-traffic-control&gt;&lt;uk&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3265" PostTypeId="1" CreationDate="2014-04-09T02:21:23.300" Score="12" ViewCount="725" Body="&lt;p&gt;On the question of &lt;a href=&quot;https://aviation.stackexchange.com/questions/2761/are-pilots-armed&quot;&gt;Are pilots armed?&lt;/a&gt;, one thing this made me think is: for the few that &lt;em&gt;are&lt;/em&gt; armed, are they allowed to bring their weapon into, for example, the UK?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the procedure? Does the gun stay in the cockpit or does it need to be checked by security once on the ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presuming a pilot had to fire a gun over EU airspace, is he breaking the law?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-06-26T20:23:53.320" Title="Are US pilots permitted to carry &amp; use their firearm in countries where guns are illegal?" Tags="&lt;security&gt;&lt;eu&gt;&lt;ffdo&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3266" PostTypeId="2" ParentId="1331" CreationDate="2014-04-09T02:45:08.803" Score="21" Body="&lt;p&gt;There is plenty of room between the request to land, and declaring an emergency to sort things out. After all, if the runway is closed, the tower isn't too busy. It would probably go something like this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;ATIS:&lt;/strong&gt; Runway 12 is closed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot:&lt;/strong&gt; Foobar approach, N12345.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; N12345 go ahead.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot:&lt;/strong&gt; Foobar approach, we are having some technical difficulties, please advise, what is the nature of the closure of runway 12? N12345.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; N12345 Threshold is being painted.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot:&lt;/strong&gt; Yeah, approach, we may have a faulty gauge, we are showing a faster fuel burn than expected, we'd like to get on the ground and take a closer look, we can land a little long.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; Roger N12345, report runway in sight.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot:&lt;/strong&gt; Runway 12 in sight, N12345.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; N12345 You are cleared to land runway 12.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The pilot is then obligated to buy a box of donuts for the tower, and thank the tower and the ground crew. He may get a warning, but equipment failures do happen, and they aren't always an emergency.&lt;/p&gt;&#xA;&lt;p&gt;Everybody makes mistakes. Aviation is as much an art as a science. So while the rules are important, they are only religion to the lawyers, and only then after something goes horribly wrong. To the people who actually work in aviation, it is about safety, and professionalism, and being good at what you do. And that requires a certain amount of flexibility.&lt;/p&gt;&#xA;" OwnerUserId="2078" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-09T02:51:30.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3267" PostTypeId="1" AcceptedAnswerId="3279" CreationDate="2014-04-09T02:45:43.147" Score="5" ViewCount="501" Body="&lt;p&gt;Last August during a certification flight, a Cessna 182JT-A compression-ignition (diesel) engine failed in flight. I've been Googling to find the cause of the failure and the status of the certification process but have failed to find any recent info. Does anyone know what the current findings have been and how Cessna expects to proceed?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="247" LastEditDate="2014-07-07T03:49:19.103" LastActivityDate="2014-07-07T03:49:19.103" Title="Has the cause of the engine failure of Cessna's 182JT-A been determined?" Tags="&lt;aircraft-certification&gt;&lt;engine-failure&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3268" PostTypeId="1" CreationDate="2014-04-09T03:03:31.307" Score="2" ViewCount="287" Body="&lt;p&gt;In the US, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Federal_Flight_Deck_Officer&quot; rel=&quot;nofollow&quot;&gt;FFDO programme&lt;/a&gt; trains and permits pilots to carry a firearm in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any other countries have a similar programme?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="72" LastEditDate="2014-04-09T03:18:17.907" LastActivityDate="2014-11-14T17:11:16.637" Title="Which countries permit pilots to carry a firearm?" Tags="&lt;security&gt;&lt;ffdo&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3269" PostTypeId="1" AcceptedAnswerId="7873" CreationDate="2014-04-09T03:11:55.600" Score="14" ViewCount="686" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Federal_Flight_Deck_Officer&quot;&gt;Federal Flight Deck Officer&lt;/a&gt; page on Wikipedia says this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Under the FFDO program, flight crew members are authorized to use firearms. A flight crew member may be a pilot, flight engineer or navigator assigned to the flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To me, it seems like this would be crucial information for the PIC to know, if their flight engineer (for example) was armed; but on the flip-side of this, the engineer might want to keep that to himself if he's with a crew he hasn't flown with before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a guideline on whether an FFDO should inform the crew that he's armed?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T21:31:41.850" LastActivityDate="2014-07-24T02:54:45.443" Title="Would a pilot know that one of their crew is armed?" Tags="&lt;security&gt;&lt;crew&gt;&lt;ffdo&gt;" AnswerCount="1" CommentCount="12" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3271" PostTypeId="1" CreationDate="2014-04-09T03:29:25.510" Score="12" ViewCount="1138" Body="&lt;p&gt;The &lt;a href=&quot;http://www.soloy.com/Products/Fixed%20Wing%20Aircraft/Soloy%20Dual%20Pac/default.aspx&quot; rel=&quot;noreferrer&quot;&gt;Soloy Dual Pac&lt;/a&gt; apparently allows two engines to rotate one propeller -- here's a picture of it on an Otter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/I59fe.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this recognised as a centreline thrust twin engine aircraft, a &quot;standard&quot; twin engine aircraft or just an aircraft with a single engine for FAA certification? What about for pilot licensing?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="19" LastEditDate="2015-01-09T23:58:02.147" LastActivityDate="2017-06-03T00:40:32.867" Title="Is the Soloy Dual Pac recognised as two engines or one engine?" Tags="&lt;faa-regulations&gt;&lt;piston-engine&gt;&lt;pilot-certification&gt;&lt;aircraft-certification&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3272" PostTypeId="1" AcceptedAnswerId="3293" CreationDate="2014-04-09T03:31:15.600" Score="8" ViewCount="17020" Body="&lt;p&gt;When filing a flight-plan for a long-haul high-altitude IFR flight, how do pilots select a specific cruising altitude? Typically in the range of 25,000 - 35,000 ft.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T17:18:19.450" LastActivityDate="2015-02-09T23:07:02.183" Title="How do pilots decide what their cruising altitude will be?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;&lt;cruise&gt;&lt;flight-plans&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3273" PostTypeId="2" ParentId="751" CreationDate="2014-04-09T03:51:53.233" Score="4" Body="&lt;p&gt;Since Seattle was mentioned in the original poster's question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recently asked one of the SeaTac approach controllers at a conference about this, they said they were completely fine with it. As long as you asked early enough so they can get you sequenced in, they can put you on 16R/34L and you are out of the way of other traffic. That runway is fairly new (built in 2008), and so perhaps it was more of a problem years ago when they only had two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, they might clear you for the option instead of clearing you to land. That way, you have plausible deniability that you did land, and might get out of a landing fee.&lt;/p&gt;&#xA;" OwnerUserId="451" LastActivityDate="2014-04-09T03:51:53.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3274" PostTypeId="2" ParentId="3272" CreationDate="2014-04-09T03:53:11.170" Score="1" Body="&lt;p&gt;Cruise altitude may be assigned by ATC for separation (IFR especially, or in other controlled airspace -- since, in the US, these altitudes would be Class A and controlled airspace).  For example, when you request a DUAT(S) briefing, it will usually give suggested ATC routing and also altitude assignments (along with what's most frequently used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude you request somewhat depends on aircraft performance, I would imagine, but obviously any ATC clearance must be adhered to unless amended.  Hopefully one of the commercial pilots can fill in more of the blanks, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also: &lt;a href=&quot;http://www.flyingmag.com/blogs/flying-time/choosing-appropriate-altitude&quot; rel=&quot;nofollow&quot;&gt;Choosing an Appropriate Altitude&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2074" LastActivityDate="2014-04-09T03:53:11.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3275" PostTypeId="5" CreationDate="2014-04-09T03:58:51.797" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-09T03:58:51.797" LastActivityDate="2014-04-09T03:58:51.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3276" PostTypeId="4" CreationDate="2014-04-09T03:58:51.797" Score="0" Body="The Federal Flight Deck Officer program trains and permits US crewmembers to carry firearms in-flight." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-09T20:05:50.057" LastActivityDate="2014-04-09T20:05:50.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3277" PostTypeId="2" ParentId="3261" CreationDate="2014-04-09T04:11:39.850" Score="6" Body="&lt;p&gt;At least three of the &quot;fallback systems&quot; I know of are looking out the window, being familiar with the airport and its markings (as well as associated hotspots, as airport diagrams may indicate), and also paying attention to the radio, if you're equipped.  Of course, no one of these methods is foolproof, so it takes a combination of alertness and prudence to avoid incursions.  I was taught to look both ways before intersections, or to look both ways before entering a runway, just to make sure I didn't miss anything.  Also, using lighting on your aircraft appropriately helps make you more visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other planes may not have a radio, so you may not hear a radio call of someone else in the pattern.  Also, at a complex intersection in a new airport, it may be confusing where you are, or what hold short lines you're about to cross -- so being aware of your surroundings is important here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some technologies the FAA has been implementing to reduce the risk of runway incursions, such as Elevated Runway Guard Lights and stop bar lights, plus ground radar technologies (for ATC) to assist (see &lt;a href=&quot;http://en.wikipedia.org/wiki/Airport_Surface_Detection_Equipment,_Model_X&quot; rel=&quot;nofollow&quot;&gt;ASDE-X&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Airport_Movement_Area_Safety_System&quot; rel=&quot;nofollow&quot;&gt;AMASS&lt;/a&gt;).  Note that your A/FD entry may list, for example, that not all taxiways are visible from the tower -- which is a good reason to stay extra alert.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/airports/runway_safety/media/pdf/PHAK%20-%20Appendix%201%20-%20April%202012.pdf&quot; rel=&quot;nofollow&quot;&gt;Runway Incursion Avoidance&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Runway_incursion&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An additional FAA training video:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=Ql6F9RFbjMA&quot; rel=&quot;nofollow&quot;&gt;Airport Signs, Markings, and Procedures: Your Guide to Avoiding Runway Incursions&lt;/a&gt; (Because John and Martha King.... and Harrison Ford!)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2074" LastEditorUserId="2074" LastEditDate="2014-04-09T04:25:57.123" LastActivityDate="2014-04-09T04:25:57.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3279" PostTypeId="2" ParentId="3267" CreationDate="2014-04-09T04:45:01.433" Score="8" Body="&lt;p&gt;Apparently, yes, it has -- see &lt;a href=&quot;http://www.flyingmag.com/aircraft/pistons/cessna-182-jt-certification-imminent&quot;&gt;Cessna 182 JT-A Certification 'Imminent'&lt;/a&gt;.  As the article reports, the issues appeared to be related to the turbocharger, but I'm not sure how far (if at all) accident reports or details go beyond that.&lt;/p&gt;&#xA;" OwnerUserId="2074" LastActivityDate="2014-04-09T04:45:01.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3280" PostTypeId="2" ParentId="3264" CreationDate="2014-04-09T06:07:03.183" Score="34" Body="&lt;p&gt;&lt;a href=&quot;https://www.ofcom.org.uk/__data/assets/pdf_file/0027/89037/Guidance-on-Receive-Only-Radio-Scanners.pdf&quot; rel=&quot;noreferrer&quot;&gt;Yes, it is illegal&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The UK has some &lt;em&gt;very strange ideas&lt;/em&gt; about Radio, which bear no resemblance to the reality of physics and how radio actually works. Foremost among those ideas is the idea that you are only legally allowed to listen to transmissions intended for &quot;general reception&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The services that can be listened to under the definition of general reception are:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;licensed broadcasting stations;&lt;/li&gt;&#xA;  &lt;li&gt;amateur and citizens' band radio transmissions; and&lt;/li&gt;&#xA;  &lt;li&gt;weather and navigation transmissions&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;Radio scanners should not be used to listen to any other radio services, including illegal radio stations (pirates) (by virtue of the fact that they are not licensed radio stations).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aviation-band transmissions are not on Ofcom's list, so even though they are broadcast entirely &quot;in the clear&quot; and anyone with an appropriately tuned AM receiver could hear them you are legally prohibited from listening to them.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Providing feeds to LiveATC would also appear to be a violation, though it's not clear to me that listening to LiveATC streams would put &lt;em&gt;the listener&lt;/em&gt; in violation of the law.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the same Ofcom site:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;… it is illegal to listen to anything other than general reception transmissions unless you are either a licensed user of the frequencies in question or have been specifically authorised to do so by a designated person.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;… it is also illegal to tell a third party what has been heard in a transmission a person has listened to illegally.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So anyone &lt;strong&gt;providing UK aviation band transmissions to LiveATC&lt;/strong&gt; &lt;em&gt;may&lt;/em&gt; be in violation of both of those laws, but I'm not certain what that means for LiveATC &lt;em&gt;listeners&lt;/em&gt; (that would be a question to ask Ofcom).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="487" LastEditDate="2018-08-28T22:07:26.717" LastActivityDate="2018-08-28T22:07:26.717" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="3281" PostTypeId="1" AcceptedAnswerId="3282" CreationDate="2014-04-09T06:13:53.007" Score="14" ViewCount="1508" Body="&lt;p&gt;I'm a student pursuing a US Private Pilot License, and recently scheduled my checkride. I've been training in a 1981 Piper Warrior (PA-28-161), but if its annual goes sour I may have to take my club's 1980 Piper Archer (PA-28-181). I have well over &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1e1e0bd4fafa851220faffbc862c0861&amp;amp;node=14:2.0.1.1.2&amp;amp;rgn=div5#14:2.0.1.1.2.5.1.5&quot; rel=&quot;noreferrer&quot;&gt;§61.109's 40 hours&lt;/a&gt; in the Warrior alone, and only ~10 hours in the Archer. I have a separate club checkout and CFI solo endorsement for each, they're pretty similar anyway—they're even both the same ATC type (P28A)—but they aren't the same &lt;em&gt;model&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Here's the catch: &lt;a href=&quot;http://www.faa.gov/forms/index.cfm/go/document.information/documentid/185868&quot; rel=&quot;noreferrer&quot;&gt;Form 8710&lt;/a&gt;, the &amp;quot;Airman Certificate and/or Rating Application&amp;quot;, asks specifically for&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[II.A.2.] Total time in this make/model and/or approved FFS or FTD (Hrs.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Furthermore, according to the &lt;a href=&quot;https://iacra.faa.gov/iacra/FAQ.aspx&quot; rel=&quot;noreferrer&quot;&gt;IACRA FAQ&lt;/a&gt; (&amp;quot;I'm a Designated Examiner. I noticed a mistake when reviewing the IACRA application....&amp;quot;):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A mistake in the applicant's information cannot be corrected after it has been signed by the Recommending Instructor.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;My prospective DPE explicitly told me that the backup plane was fine, and I can't find any Part 61 regulations that are specific to experience in one make/model aside from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;SID=257acc4699ee7253af775fc7e9492e51&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.2.1.2&quot; rel=&quot;noreferrer&quot;&gt;adding an experimental aircraft as part §61.63(h)(1)&lt;/a&gt;, which is what I assume the box is really for. Of course I'd rather test in my more-experienced plane, but I'm asking specifically for regulations here if Plan A falls through.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Are there any regulations or headaches that I would encounter if I need to change the tail number or model number of my checkride plane and listed hours therein, potentially long after IACRA submission?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1042" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-30T15:06:09.957" Title="Backup plane for checkride: Can it be a different model?" Tags="&lt;faa-regulations&gt;&lt;ppl&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3282" PostTypeId="2" ParentId="3281" CreationDate="2014-04-09T06:33:25.017" Score="6" Body="&lt;p&gt;I came to the same conclusion as you, I don't see anything keeping you from going. You meet the requirements of 61.107 and 61.109, you have recent experience in both aircraft, and as far as make and model, they're both PA-28's. That's like going from a 172B to a 172S: it's the same make and model, Piper just makes it a little less obvious with their nickname and number combinations. If you had trained in a Warrior 160 and an Arrow, it would be a bit different, but only as far as requiring an additional endorsement.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-09T06:33:25.017" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3283" PostTypeId="2" ParentId="3271" CreationDate="2014-04-09T06:42:31.977" Score="7" Body="&lt;p&gt;According to the &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/e12680b66a5e1ef986256fe0006aef6c/%24FILE/SE00482SE.pdf&quot; rel=&quot;noreferrer&quot;&gt;certificate&lt;/a&gt; is a&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Twin Power Section Turboprop&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and, later, note 7: (emphasis mine)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This engine is certificated as a unit comprising two separate power sections with the capability of single engine operation with either power section alone in multi-engine airplanes. &lt;strong&gt;The unit is also approved as a single engine with either or both engines operating continuously&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No explicit remark is given about pilot licensing, but given the note reported, I would say that a licence for a single engine is sufficient.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-04-09T06:57:13.797" LastActivityDate="2014-04-09T06:57:13.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3284" PostTypeId="2" ParentId="3272" CreationDate="2014-04-09T07:53:56.710" Score="5" Body="&lt;p&gt;I guess you know the FAR rules for picking discrete values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it comes to performance, with a jet you want to fly as high as possible. The only reason not to do so is total distance; on a short hop there is not enough flying time to climb all the way up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher you fly (in the troposphere) the colder the air is, which makes the thermodynamic cycle of all air-breathing engines more efficient. Also, the air gets thinner, so your friction drag is reduced at the same TAS. The specifics depend on the thrust over airspeed, and generally you want to fly at a lift coefficient between $\sqrt{\frac13\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$ and $\sqrt{c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$, where $c_{D0}$ is the zero-lift drag and $AR$ the wing's aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher value is perfect for piston engines and props, and the lower one for turbojets (think fighter aircraft engine). With a turbofan you will be between both values. To yield more precise results, both formulas will be longer, but these are the major factors for optimum lift coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since there is an optimum cl for maximum range, you might want to climb continuously during the flight to compensate for the lower mass (due to fuel burn) with lower air density, so in reality you adjust altitude in steps, in accordance with traffic control. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-09T20:48:37.680" LastActivityDate="2015-02-09T20:48:37.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3285" PostTypeId="2" ParentId="3264" CreationDate="2014-04-09T09:26:49.287" Score="2" Body="&lt;p&gt;Basic legislation within the EU, specifies that your are allowed to listen to any type of information available on the electromagnetic spectrum. It is up to the users to protect said information by using encryption if so required.&#xA;This is not to say that there is not some very restrictive legislation in place in some countries. They just hate the thought of their citizens getting informations of almost any kind. Ignore the law and take your complaints to the courts in Brussels. The local authorities will hate you for that, but you will probably win the case.&lt;/p&gt;&#xA;" OwnerUserId="2079" LastEditorUserId="97" LastEditDate="2014-04-09T15:36:29.553" LastActivityDate="2014-04-09T15:36:29.553" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3286" PostTypeId="1" CreationDate="2014-04-09T10:36:20.637" Score="6" ViewCount="1926" Body="&lt;p&gt;If an incident occurs on board an aircraft in flight which could be considered as criminal in one country, what decides which country the incident falls under? For example, if a man was found to be in possession of &quot;virtual&quot; child pornography and not all of the countries involved consider that to be illegal, which country is the one who decides whether the person have broken the law or not?&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2014-04-09T15:03:34.630" Title="Which country has jurisdiction over incidents in flight?" Tags="&lt;airspace&gt;&lt;international&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-04-09T15:51:48.260" ContentLicense="CC BY-SA 3.0" />
  <row Id="3288" PostTypeId="2" ParentId="3264" CreationDate="2014-04-09T12:08:30.497" Score="9" Body="&lt;p&gt;Strictly speaking it is against the law, the transmission is not intended for public reception (indicated by it falling outside of public broadcast frequencies) and you are not the intended recipient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However you will find that in practice this is ignored on a personal basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. yourself listening nobody has a problem with, if you were to then make what you hear available elsewhere whether via retransmission, recording or transcript I would expect a knock on the door from Ofcom&lt;/p&gt;&#xA;" OwnerUserId="2080" LastActivityDate="2014-04-09T12:08:30.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3289" PostTypeId="1" AcceptedAnswerId="3291" CreationDate="2014-04-09T12:52:44.220" Score="6" ViewCount="1219" Body="&lt;p&gt;Was wondering if ATC can detect if aircraft is being flown manually vs. autopilot and if that affects their clearances given out for surrounding aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More specifically, can they tell through ADSB signal or just by observation (holding flight level, turn rate, correction for wind, etc)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would imagine that in high winds/bad weather non-AP operation would need to be better isolated from other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="795" LastEditDate="2014-04-10T08:24:34.553" LastActivityDate="2014-04-10T08:33:28.887" Title="Can ATC tell if aircraft is being flown manually?" Tags="&lt;air-traffic-control&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3290" PostTypeId="2" ParentId="3289" CreationDate="2014-04-09T13:24:28.147" Score="-4" Body="&lt;p&gt;The autoPILOT is not for ATC's convenience. They neither know nor care if it's on, off, or trailing behind the airplane on it's cables. All ATC cares about is that the &lt;em&gt;transponder&lt;/em&gt; works, and even that isn't a requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC may suspect something is amiss if the aircraft is not holding heading or altitude very well, but if ATC notices this we are well into a major problem. Either there's a major malfunction onboard or the plane is no longer under the control of a competent pilot. Any pilot who passed their commercial can hold heading and altitude just as well as the box - I have zero formal instruction and I can hold a Cessna on course to the point where no one will notice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cases where the plane is fine but the crew has a major malfunction (like dying, à la Payne Stewart) then ATC will consider what mode the autopilot is likely in, as that will tell them where the plane will probably be when it runs out of fuel. (If it's turned off, the discussion will never get to this point on account of the plane already turning into a lawn dart)&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-04-09T13:24:28.147" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3291" PostTypeId="2" ParentId="3289" CreationDate="2014-04-09T14:14:19.700" Score="10" Body="&lt;p&gt;No, the air traffic controller cannot see the whether the autopilot is used or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in the Mode S radar and ADS-B protocols there are messages defined that contain state of the autopilot. Currently there is no requirement that this data is provided by the aircraft, but some aircraft/transponders do provide the information nevertheless. The data is not displayed to the controller though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some control centres the aircraft's Mode Control Panel / Flight Control Unit Selected Altitude can be displayed to the air traffic controller. The information can be used to reduce Level Busts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From observations of the radar track it is difficult to tell. A competent pilot will be able to maintain altitude and heading in such a way that it is difficult to see the difference from an autopilot at the resolution of the ATC display. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are circumstances where the pilot is required to use the autopilot, especially to keep separation from other aircraft. In Reduced Vertical Separation Minima (RVSM) airspace the vertical separation is 1000 ft between Flight Level 290 and FL410. The aircraft must be flown using the autopilot in this airspace to ensure the flight levels are adhered to strictly.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-04-10T08:33:28.887" LastActivityDate="2014-04-10T08:33:28.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3292" PostTypeId="1" CreationDate="2014-04-09T14:28:41.440" Score="13" ViewCount="3343" Body="&lt;p&gt;Can an airport not eligible for an FAA tower and controllers choose to fund their own air traffic control tower? Can that airport require pilots to taxi, approach, land, and take off according to their tower's instructions? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, are there requirements for the controllers in terms of certification, or can they hire anyone they deem suitable for their airport? Do they have to coordinate with the FAA or air traffic control system in some special way?&lt;/p&gt;&#xA;" OwnerUserId="1073" LastEditorUserId="-1" LastEditDate="2014-04-09T15:07:11.067" LastActivityDate="2014-04-09T17:37:41.003" Title="Can an airport without an FAA controlled tower have their own tower and controllers?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;&lt;faa&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3293" PostTypeId="2" ParentId="3272" CreationDate="2014-04-09T14:31:53.253" Score="11" Body="&lt;p&gt;As has been stated, ATC will assign you an altitude, taking into account your requested altitude, traffic conditions, and of course the FAR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/3284/1696&quot;&gt;Peter's formulas&lt;/a&gt; will apply from a design standpoint. The aircraft designer will use something like that to calculate typical values, which will be included in the aircraft's operating handbook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The table below is listed by pressure altitude and gross weight. At each combination there will be performance values such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Average N1 (for a turbine)&lt;/li&gt;&#xA;&lt;li&gt;Max TAT for thrust rating&lt;/li&gt;&#xA;&lt;li&gt;IAS Knots&lt;/li&gt;&#xA;&lt;li&gt;Mach number&lt;/li&gt;&#xA;&lt;li&gt;ISA fuel flow LB/HR/ENG&lt;/li&gt;&#xA;&lt;li&gt;ISA TAS Knots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The flight distance will determine the approximate gross weight, which corresponds to an altitude and cruise speed that provide the best efficiency. Here is an example from a &lt;strong&gt;virtual&lt;/strong&gt; 737 handbook, with the values I listed. The optimum performance is in blue. Higher gross weights have been removed for clarity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aOaKF.png&quot; alt=&quot;737-800 Optimum Cruise Altitude Table&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines may have their own performance tables, choosing a custom balance of efficiency and speed. Dispatchers for the airline will take the flight information and decide on a cruising altitude for filing the flight plan, which the pilot will then receive. As you can see, as the aircraft burns fuel and gets lighter, it will be more efficient at higher altitudes. This is the step climb that Peter mentioned, where the aircraft will climb to higher altitudes as the flight progresses when they are cleared by ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern planning systems can take into account weather factors such as winds aloft and turbulence to pick the most efficient route.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-09T23:07:02.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3294" PostTypeId="2" ParentId="3286" CreationDate="2014-04-09T15:03:34.630" Score="4" Body="&lt;p&gt;In my PPL class I was taught a simplified explanation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a baby was born (or a crime committed for that matter) on an aircraft, the official country in which it was born depends on wether the aircraft's doors are open or closed (within reasonable limits, so assuming they can't be open in flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the doors are open, the country will be the country where the aircraft is currently located. If the doors are closed, it will be the country in which the aircraft is registered.&lt;/p&gt;&#xA;" OwnerUserId="2082" LastActivityDate="2014-04-09T15:03:34.630" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3295" PostTypeId="2" ParentId="3292" CreationDate="2014-04-09T15:10:25.340" Score="3" Body="&lt;p&gt;The FAA has a &lt;a href=&quot;http://www.contracttower.org/&quot; rel=&quot;nofollow&quot;&gt;Contract Tower&lt;/a&gt; program for some airports. The government pays for them and the FAA has oversight in their operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know when the FAA was going to close a bunch of towers, some airports were considering funding the towers themselves. Based on that, I think the answer is yes, they can fund their own and it will have the same authority as any other tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More information is also &lt;a href=&quot;http://savecontracttowersnow.com/what-are-contract-towers/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.natca.org/who_we_are.aspx?zone=Who%20We%20Are&amp;amp;pID=489&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-04-09T15:10:25.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3296" PostTypeId="2" ParentId="3292" CreationDate="2014-04-09T15:17:56.633" Score="19" Body="&lt;p&gt;Yes, in fact there are a number of Non-Federal Control Towers (NFCT) in the United States.  These are NOT the same as Federal Contract Towers (FCT), which are funded by the FAA and operated by contract personnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFCTs, on the other hand, are usually funded by the local airport authority.  Some examples (not authoritative or all inclusive): Mojave (MHV), Laughlin/Bullhead City (IFP), and Merritt-Titusville (COI).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, there isn't a consolidated list of all NFCTs.  Rather, they are tracked by their respective FAA region.  Here are the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/SO/SO1100.49B.pdf&quot;&gt;Southern&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/directives/WP/WP1100-33D.PDF&quot;&gt;Western-Pacific&lt;/a&gt; Hub Organization Orders that list their respective NFCTs (not sure if they're current).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operation of NFCTs is covered by &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-93B.pdf&quot;&gt;AC 90-93b&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="97" LastEditDate="2014-04-09T17:37:41.003" LastActivityDate="2014-04-09T17:37:41.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3297" PostTypeId="1" AcceptedAnswerId="3298" CreationDate="2014-04-09T16:27:49.113" Score="8" ViewCount="10045" Body="&lt;p&gt;We are thinking about buying a telescope for viewing planets, stars, the moon, and aircraft! What is the absolute minimum zoom and/or size to achieve getting a good glimpse of an aircraft at its cruising altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have experience doing this that they could share to help us out?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastEditorUserId="65" LastEditDate="2015-02-26T16:10:27.667" LastActivityDate="2020-09-05T00:18:37.483" Title="For airplane spotting, what minimum specs should a telescope have?" Tags="&lt;plane-spotting&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3298" PostTypeId="2" ParentId="3297" CreationDate="2014-04-09T17:34:17.113" Score="16" Body="&lt;p&gt;I would not recommend a telescope for viewing aircraft.&lt;br&gt;&#xA;As others have pointed out, a telescope that is suitable for astronomy would be &lt;em&gt;incredibly&lt;/em&gt; overpowered for viewing aircraft - the aircraft would move out of the viewing frame very quickly, and you would have a difficult time tracking them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would suggest picking up a &lt;a href=&quot;http://www.amazon.com/b?node=3168061&quot;&gt;spotting scope&lt;/a&gt; (the kind of thing bird watchers and hunters use - good ones can be had in the 50 to 100 dollar price range, and excellent ones abound from about $100 up), or a pair of good binoculars for your plane watching. The zoom factor is far better suited to plane spotting, and either option would be substantially more portable than a full telescope rig.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for advice on a telescope, there is an Astronomy stack exchange site, and while &lt;a href=&quot;http://blog.stackoverflow.com/2010/11/qa-is-hard-lets-go-shopping/&quot;&gt;the entire network generally doesn't do &quot;product recommendations&quot;&lt;/a&gt; the Astronomy site's &lt;a href=&quot;http://chat.stackexchange.com/&quot;&gt;chat&lt;/a&gt; might be a good place to ask for advice on picking a telescope. (I'm not sure how active their chat room is, but it's worth a shot!)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="556" LastEditDate="2014-04-11T15:50:14.270" LastActivityDate="2014-04-11T15:50:14.270" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3299" PostTypeId="1" CreationDate="2014-04-09T18:23:41.160" Score="4" ViewCount="973" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;(b) Authorization to perform certain solo flights and cross-country flights. A student pilot must obtain an endorsement from an authorized instructor to make solo flights from the airport where the student pilot normally receives training to another location. A student pilot who receives this endorsement must comply with the requirements of this paragraph.&lt;/p&gt;&#xA;&lt;p&gt;(1) Solo flights may be made &lt;strong&gt;to&lt;/strong&gt; another airport that is within 25 nautical miles from the airport where the student pilot normally receives training&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The student must be endorsed with something along the lines of:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;I certify that (First name, MI, Last name) has received the required training of section 61.93(b)(1). I have determined that he/she is proficient to practice solo takeoffs and landings at (airport name). The takeoffs and landings at (airport name) are subject to the following conditions: (List any applicable conditions or limitations.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Emphasis on the word TO, in (1). I interpret this as &amp;quot;You must be endorsed to fly solo TO another airport for takeoffs and landings.&amp;quot; However, my instructor, and it would seem the majority of the instructors at my school interpret it as &amp;quot;You must be endorsed to fly solo AT another airport for takeoffs and landings.&amp;quot; The FARs seem to imply my interpretation, and the recommended endorsement seems to imply the opposite (in fact the endorsement doesn't even mention the 25nm part except in title).&lt;/p&gt;&#xA;&lt;p&gt;The situation it is used in most commonly is the towered-field TO/LDG practice. There is a towered field about 10 miles north of our airport where we all go to practice. However, the instructor is required to fly dual up there, solo the student, and fly dual back. Is this endorsement required in that case?&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-09T19:59:34.090" Title="What is the intent of 61.93(b)(1)?" Tags="&lt;faa-regulations&gt;&lt;cfi&gt;&lt;logbook-endorsements&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3300" PostTypeId="1" CreationDate="2014-04-09T18:41:17.607" Score="83" ViewCount="171529" Body="&lt;p&gt;Why are quadcopters not flown by human pilots yet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't they be more stable and easier to control than helicopters?&lt;/p&gt;&#xA;" OwnerUserId="2084" LastEditorUserId="15311" LastEditDate="2017-12-27T13:32:48.517" LastActivityDate="2020-06-15T16:37:24.937" Title="Why haven't quadcopters been scaled up yet?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;rotorcraft&gt;&lt;quadcopter&gt;" AnswerCount="18" CommentCount="8" FavoriteCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="3302" PostTypeId="2" ParentId="3300" CreationDate="2014-04-09T19:14:07.267" Score="9" Body="&lt;p&gt;Scaling up the quadcopter design would make them very large. Only having one (or even two) rotor allows the helicopter to be smaller and even fold up the rotors and remain fairly compact. Since by definition helicopters are supposed to get into more difficult landing areas, increasing the footprint is generally undesirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the power system would be complicated. RC quadcopters use an electric motor on each rotor for independent control. A larger version would probably use turbines like most helicopters, and they would either need 4 turbines or a way to gear fewer turbines to 4 rotors. This just adds complexity to the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_CH-47_Chinook&quot;&gt;Chinook&lt;/a&gt; is an example of a helicopter that uses two rotors, but the added complexity makes it undesirable unless the added lifting power is needed.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-04-09T19:14:07.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3303" PostTypeId="2" ParentId="3299" CreationDate="2014-04-09T19:47:23.530" Score="3" Body="&lt;p&gt;The intent of the regulation lies at the beginning, in 61,93(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=cb8a7ccdd9496bc7d06c9c1987b560f4&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2.3.1.7&amp;amp;idno=14&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;§61.93   Solo cross-country flight requirements.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) General. (1) Except as provided in paragraph (b) of this section,&#xA;  a student pilot must meet the requirements of this section before—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Conducting a solo cross-country flight, or any flight greater than&#xA;  25 nautical miles from the airport from where the flight originated.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Making a solo flight and landing at any location other than the&#xA;  airport of origination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Training and an endorsement from an instructor is required before you fly cross-country or to another airport to land.  61.93(b) covers what the instructor must do with you before you can do anything specified in 61.93(a).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the scenario that you describe you are not &quot;Conducting a solo cross-country flight, or any flight greater than 25 nautical miles from the airport from where the flight originated&quot; or &quot;Making a solo flight and landing at any location other than the airport of origination&quot; so subsection (b) does not need to be complied with at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The endorsement would only be needed if you were going to takeoff solo from your home airport, fly to the destination (which as you said is only 10 miles away), and land there since it is required by 61.93(a)(ii).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-09T19:59:34.090" LastActivityDate="2014-04-09T19:59:34.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3304" PostTypeId="2" ParentId="3300" CreationDate="2014-04-09T21:41:29.400" Score="34" Body="&lt;p&gt;It has (sort of) been done:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CgXJf.jpg&quot; alt=&quot;(not a quad)copter lifting a pilot&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.e-volo.com/&quot; rel=&quot;noreferrer&quot;&gt;The company that did this&lt;/a&gt; is working on a more useful version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's important to note that scaling up is extremely difficult in aviation.  Model airplanes have performance numbers the full scale folks can only dream about.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-04-09T21:41:29.400" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3305" PostTypeId="2" ParentId="3300" CreationDate="2014-04-10T06:48:29.327" Score="105" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Wouldn't they be more stable and easier to control than helicopters?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, they would not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quadcopters don't have any special inherent stability. When you increase power of one of the rotors to pitch, the increasing pitch will not do anything to the power difference and therefore the pitching moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage of quadcopters is that the rotors can be fixed pitch while single (or double) rotor helicopter needs complex control mechanism. While this is huge advantage for the small scale devices where each rotor can be powered by its own simple electric motor, the complexity of either additional engines or long transmission shafts would outweigh any advantage from the simpler rotors in full-scale vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And why can't full-scale helicopters use electric motors like the small ones? The reason is that when you scale an airfoil up, the lift it produces increases with its &lt;em&gt;area&lt;/em&gt;, which grows with the second power of size, but its weight increases with &lt;em&gt;volume&lt;/em&gt;, which grows with the &lt;em&gt;third&lt;/em&gt; power of size. Therefore models have much more lift for weight and can afford simple but relatively heavy batteries while full-size aircraft need propulsion systems with higher power density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is also the factor of safety. In case of power failure, helicopters can still glide to the ground and still land vertically using autorotation. But since the rotor rotating speed can't be changed without power, controlling the helicopter during such manoeuvre requires variable pitch rotor. So there goes the main advantage of quadcopters.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-10-05T19:02:24.767" LastActivityDate="2014-10-05T19:02:24.767" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3306" PostTypeId="1" CreationDate="2014-04-10T07:02:21.017" Score="49" ViewCount="103288" Body="&lt;p&gt;Jet engines are by their very nature push-engines, however, most propeller airplanes use pull-engines. Is there an inherent advantage to using pull-propellers except for the increased airflow over the fuselage and tail (with its rudder and elevator)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Twins generally have their engines on the wings, and the tail is no longer directly behind it, does that mean the choice of a pull-engine is not as advantageous?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there isn't an inherent disadvantage, why are pusher configurations so rare? If there is one, why do they exist at all? Disregarding designs where the choice is obvious, like powered parachutes where you simply don't want a propeller &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Powered-parachute-flying.jpg&quot;&gt;in your face&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_B-36&quot;&gt;Convair B36&lt;/a&gt; is one notable multi-engine aircraft with engines in pusher configuration, as is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Piaggio_P-180_Avanti&quot;&gt;Piaggio Avanti&lt;/a&gt;. And the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_Skymaster&quot;&gt;Cessna Skymaster&lt;/a&gt; is a push/pull configuration (If you get a multi-engine rating in a Skymaster, your ticket will be limited to multi-engine aircraft with in-line thrust). Single engine aircraft are even more uncommon, and pretty much all I could find except the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lake_Buccaneer&quot;&gt;Lake Buccaneer&lt;/a&gt; are all kit-planes (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Velocity_XL&quot;&gt;Velocity&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Rutan_Long-EZ&quot;&gt;Rutan&lt;/a&gt;), ultralights (&lt;a href=&quot;http://en.wikipedia.org/wiki/Quad_City_Challenger&quot;&gt;Quad City&lt;/a&gt;), military, or experimental.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="1696" LastEditDate="2014-10-27T15:43:19.160" LastActivityDate="2020-04-08T17:35:27.173" Title="Why are push-propellers so rare, yet they are still around?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="12" CommentCount="7" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3307" PostTypeId="2" ParentId="3306" CreationDate="2014-04-10T07:17:51.467" Score="5" Body="&lt;p&gt;For single engine aircraft at least, having a pusher prop makes egress in flight (a.k.a. bailing out or ejecting) much more dangerous. During WW1 I believe (when pusher props were far more common) more than a few pilots were seriously injured or killed by their props when having to jump out of a burning aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason the Germans fitted (or planned to) an ejection seat in their Do.335 push/pull design, and Fokker planned to do the same in his D.XXIII.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-36 was large enough that pusher props would be far away from the fuselage, getting rid of that problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An advantage I can think of of having the props in the front that stems from the increased airflow is that you get free extra cooling of the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the engine in a single engine design in the rear with a pusher prop, you end up with a more complex air inlet and tail design than simply letting the engine suck in air that it bites into already. You need ducts and stuff, adding weight and complexity.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="11671" LastEditDate="2018-07-29T18:36:03.987" LastActivityDate="2018-07-29T18:36:03.987" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="3308" PostTypeId="2" ParentId="3306" CreationDate="2014-04-10T07:48:09.930" Score="49" Body="&lt;p&gt;There are many disadvantages, they seem to outweigh the advantages.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are two:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;A pusher prop is working in a disturbed airflow, causing increased vibration and noise&lt;/strong&gt;&lt;br&gt;&#xA;If the propeller is fitted behind a wing, each propeller blade is passing through the separated boundary flow twice each rotation. These cycles create additional noise and lower the efficiency of the propeller. The vibration makes the propeller blades more susceptible to metal fatigue. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Propeller clearance at takeoff&lt;/strong&gt;&lt;br&gt;&#xA;Due to the pitch up at take-off, the propeller gets close to the ground. Therefore the diameter needs to be reduced (loss of efficiency) or the landing gear struts need to be made longer (added weight). Since the propeller is behind the landing gear,  it is susceptible to debris kicked up from the gear, increasing the need for added blade protection (increased weight, loss of efficiency)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pusher_configuration#Disadvantages&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; has a list of additional disadvantages. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your statement that &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Jet engines are by their very nature push-engines&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;is not entirely true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In turbofan engines, most of the thrust is generated by the fan and compressor stages. Even in a pure jet engine, a lot of thrust is generated by the compressor. Therefore the shaft of a jet engine is tension loaded, just like a propeller shaft in puller configuration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/J96zv.png&quot; alt=&quot;thrust distribution in a jet engine&quot;&gt;&#xA;Source: Rolls Royce - The Jet Engine&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="64" LastEditDate="2014-04-10T16:14:01.423" LastActivityDate="2014-04-10T16:14:01.423" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3310" PostTypeId="1" AcceptedAnswerId="3311" CreationDate="2014-04-10T14:32:22.650" Score="18" ViewCount="70484" Body="&lt;p&gt;From take-off performance calculations I remember that the take-off and initial climb was expressed in a number of segments. Each segment had its own performance requirements. I presume they are described in some FAR / JAR but I don't know whether to look under certification or operational requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the segments and how are they demarcated? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they differ for aircraft types (propeller vs. turbofan, number of engines?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these segments used for certification, operationally or both? &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-04-10T14:39:59.123" LastActivityDate="2021-04-12T01:58:00.683" Title="How are take-off segments defined?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3311" PostTypeId="2" ParentId="3310" CreationDate="2014-04-10T15:04:45.907" Score="23" Body="&lt;p&gt;You can find the 4 segment climb profile described for transport category airplanes in the (old) &lt;a href=&quot;https://catsr.vse.gmu.edu/SYST460/FAA-H-8083-25A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25A) Ch 10&lt;/a&gt; and codified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d5dad51bd56dabc931580b1171f72b2d&amp;amp;node=14:1.0.1.3.11.2.155.13&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 25.111&lt;/a&gt;.  The full 4 segment profile described below assumes an engine failure at &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; and stipulates a climb and speed profile to clear obstacles.  During normal all-engine ops this profile is still technically in place but you'll hit your speed and altitude targets in such a way that you'll takeoff into a climb with increasing airspeed and no intermediate level off (you will still likely use parts of the profile for your flap retraction schedule).&lt;/p&gt;&#xA;&lt;p&gt;The segments of the climb are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Liftoff to 35' and &lt;span class=&quot;math-container&quot;&gt;$V_2$&lt;/span&gt;&lt;br /&gt;&#xA;At liftoff you are assumed to be in takeoff configuration with at least one engine not operating.  After liftoff you will retract the gear and accelerate to &lt;span class=&quot;math-container&quot;&gt;$V_2$&lt;/span&gt; while climbing.  The goal here is the reach 35' height before the end of your takeoff distance.  Note that for propeller aircraft, this height is 50' instead of 35'.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;35' to acceleration height flown at &lt;span class=&quot;math-container&quot;&gt;$V_2$&lt;/span&gt;&lt;br /&gt;&#xA;During this segment you climb at &lt;span class=&quot;math-container&quot;&gt;$V_2$&lt;/span&gt; until you reach a height at which it is safe to level off and accelerate.  This height is called the acceleration height and is normally 400' AGL.  However, this value can vary per runway and will be available to you in your performance data for a particular runway.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Level flight at acceleration height to &lt;span class=&quot;math-container&quot;&gt;$V_{FS}$&lt;/span&gt;&#xA;You are clear of all obstacles, and now your goal shifts from altitude to airspeed.  Level the airplane and accelerate.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Continue climbing at &lt;span class=&quot;math-container&quot;&gt;$V_{FS}$&lt;/span&gt; to 1500' (typical)&lt;br /&gt;&#xA;Once &lt;span class=&quot;math-container&quot;&gt;$V_{FS}$&lt;/span&gt; is reached you will continue to climb at that airspeed.  This will also mark your transition from takeoff flaps to a clean configuration.  The height of 1500' is a typical value but may be different based on obstacles for a specific runway.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Enroute climb&lt;br /&gt;&#xA;Upon reaching 1500' (or whatever altitude is used in the previous segment) at &lt;span class=&quot;math-container&quot;&gt;$V_{FS}$&lt;/span&gt; you transition into your enroute climb.  At this altitude you will begin to perform checklists for the engine failure you experienced between &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; and liftoff and your after takeoff flows and checklists.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Jxmaa.png&quot; alt=&quot;4 segment climb profile&quot; /&gt;&lt;br /&gt;&#xA;Fig 10-36 FAA-H-8083-25A pp 10-30&lt;/p&gt;&#xA;&lt;p&gt;A transport category airplane with an engine inoperative must be able to meet the climb gradients stipulated in the image above.  The climb gradients vary by number of engines,&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="56908" LastEditDate="2021-04-12T01:58:00.683" LastActivityDate="2021-04-12T01:58:00.683" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="3312" PostTypeId="1" AcceptedAnswerId="3326" CreationDate="2014-04-10T17:25:44.230" Score="9" ViewCount="2366" Body="&lt;p&gt;Jet engines are designed to contain a fan blade failure, and the engines and airplanes are designed with this type of failure in mind. This is more critical in the modern high-bypass designs with large fans. Pictures from bird strikes sometimes show pretty severe damage, but I don't remember any that actually lost a fan blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How often does a jet engine actually lose a fan blade?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is different from a rotor burst, which is uncontained (like with &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_32&quot; rel=&quot;noreferrer&quot;&gt;Qantas Flight 32&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-10T17:35:29.233" LastActivityDate="2019-10-08T20:19:51.153" Title="How often does fan blade out happen?" Tags="&lt;safety&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3313" PostTypeId="1" AcceptedAnswerId="3314" CreationDate="2014-04-10T18:24:28.540" Score="13" ViewCount="11576" Body="&lt;p&gt;So everyone knows that carb heat decreases engine performance. Yet when we check the heat during run-up, the manifold pressure increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why is that?&lt;/strong&gt; Shouldn't adding carb heat cause the intake air to become hotter and therefore thinner, and cause the manifold pressure to decrease?&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2019-03-09T22:14:31.947" Title="Why does manifold pressure increase when you turn on carb heat?" Tags="&lt;piston-engine&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3314" PostTypeId="2" ParentId="3313" CreationDate="2014-04-10T18:31:13.020" Score="11" Body="&lt;p&gt;Because &lt;a href=&quot;http://www.avweb.com/news/pelican/182081-1.html?redirected=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;manifold pressure sucks!&lt;/a&gt; Seriously though, the manifold pressure measures how much the engine is &lt;em&gt;able to reduce the pressure&lt;/em&gt; between throttle and inlet valve by sucking air into the cylinder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you apply carb heat the air gets routed over a heat exchanger that uses some of the excess heat from the exhaust system to heat up the intake air, however the reason it becomes less dense, is because the pressure stays the same. If you look at the so called ideal gas law, you'll notice that pressure is a function of density and temperature, if you have a closed system, where the density can not change, increasing the temperature would indeed increase pressure. This is not a closed system however, so the pressure actually stays more or less the same and the density decreases, and it's not the reason for the manifold pressure increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thinner air leaves the engine with less oxygen to burn and thus it produces less power, the RPM drops, causing the engine to &quot;suck&quot; less air into the cylinder, this gives the air more time to sneak passed the throttle, and the manifold pressure rises. For the same reason the manifold pressure rises (slightly) when you reduce the RPM for cruise. Any reduction in RPM, for whatever reason &amp;ndash; engine damage for example &amp;ndash; as long as the throttle doesn't move (or if you have carb ice, which has essentially the same effect as closing the throttle), your manifold pressure will actually rise. Remember, it seems counter-intuitive, but the engine is fighting a battle with the throttle, trying to keep the manifold pressure down by sucking the air out, while the throttle is trying to increase the pressure back to atmospheric by letting air in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the throttle is anything but wide open, the situation looks like this (image borrowed from the linked article)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QoILs.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QoILs.gif&quot; alt=&quot;idle power&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.avweb.com/media/newspics/pp15idle.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;avweb.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's related to the fact that the manifold pressure gauge, when the engine is stopped, will read ambient pressure, i.e. 29.92 inHg on a standard day at sea level, which is usually interpreted as &quot;full throttle&quot;, it doesn't matter how the throttle is positioned. So it's not really showing how much fuel/air mix you're shoving into the engine. In fact, we're not shoving at all, the engine literally sucks it into the cylinder as the piston moves out of the way during the intake stroke. In this particular case with the engine off, it just means that enough air was able to sneak by the throttle and equalize the pressure. It is not flowing nearly fast enough to equalize the pressure as soon as the engine is running though.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="8282" LastEditDate="2019-03-09T22:14:31.947" LastActivityDate="2019-03-09T22:14:31.947" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="3315" PostTypeId="2" ParentId="2437" CreationDate="2014-04-10T18:55:05.173" Score="1" Body="&lt;p&gt;If the plane flew to empty, and the pilot made a manual controlled glide and water landing, he would still strike the water at a speed in excess of 150 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines would still be ripped off, baggage hold doors would most likely open on impact. There would have to be some kind of debris field. The plane would sink, but not intact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Something would come free and float to the surface.&lt;/p&gt;&#xA;" OwnerUserId="2086" LastEditorUserId="97" LastEditDate="2014-04-10T20:55:36.913" LastActivityDate="2014-04-10T20:55:36.913" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3316" PostTypeId="1" AcceptedAnswerId="3319" CreationDate="2014-04-10T19:17:08.897" Score="14" ViewCount="3174" Body="&lt;p&gt;In smaller planes, pilots has apparently great visibility in front, on the sides and a good portion of the rear of the plane. But as the plane's size is increased, the visibility is also reduced. One obvious factor is height of the cockpit from ground, but it appears (from pictures) that pilots of bigger Boeing/Airbus planes have too many blind spots. However, I did notice that some bigger planes have a camera behind the nose gear to ease in taxiing etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is that how do pilots compensate for this lesser visibility? Do they always need external help (e.g. ground crew)? Is there some sophisticated technology helping them? I am sure they cannot just raise or lower a wing or some other maneuver to check nearby traffic.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="572" LastEditDate="2015-02-19T09:44:03.130" LastActivityDate="2017-01-28T21:21:19.643" Title="How do larger aircraft compensate for reduced visibility from the cockpit, e.g. less visibility of the rear of the aircraft?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;airline-operations&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3317" PostTypeId="2" ParentId="3316" CreationDate="2014-04-10T19:43:53.707" Score="4" Body="&lt;p&gt;Small aircraft are generally under VFR rules, where they need to have that visibility to look out for other traffic. Larger aircraft usually operate under IFR rules, where (as ratchet pointed out) ATC helps to separate traffic, and TCAS will help as well. At the high speeds at which they fly, visual separation is less useful, anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, especially when you start travelling faster, what matters most is what's in front. If everyone makes sure they don't run over someone, you shouldn't have to worry about getting hit from behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When at the gate, most aircraft (even the smaller ones) will have a person guiding them in, and during pushback the tug driver has a better view and wing walkers make sure the wing tips clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When taxiing, pilots will get a feel for how to control the aircraft from training and experience. Especially in large airplanes, they can be sitting significantly forward of the front landing gear, making it a bit disorienting to maneuver if you are not used to that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, incidents happen. You may recall recent incidents where planes have clipped each other while taxiing, such as &lt;a href=&quot;http://www.bloomberg.com/news/2014-02-28/jumbo-planes-wings-brush-in-los-angeles-airport.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one at LAX&lt;/a&gt;. Because of these incidents, the &lt;a href=&quot;http://www.ntsb.gov/doclib/recletters/2012/A-12-048-049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NTSB has recommended&lt;/a&gt; that improvements such as cameras would help avoid these situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 has a camera on its tail that helps the pilots stay aware, but it is unique in this regard (though it doesn't appear to have a wide enough view to include wingtips).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V6ZgQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-11T02:23:16.427" LastActivityDate="2014-04-11T02:23:16.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3318" PostTypeId="2" ParentId="3316" CreationDate="2014-04-10T20:01:31.703" Score="3" Body="&lt;p&gt;On the ground, pilots of commercial airliners taxi without the help of ground crews except for entering and departing the gate area.  Once out on the taxiways they follow the painted line.  Keeping the nosewheel on the line pretty much guarantees that there is enough clearance for the plane including the wingspan.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-04-10T20:01:31.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3319" PostTypeId="2" ParentId="3316" CreationDate="2014-04-10T20:03:09.900" Score="15" Body="&lt;p&gt;Appearances can be deceiving. The view &quot;behind&quot; a Piper Cherokee looks something like the image below: no rear window so you can't see what's behind you, but that really doesn't matter since there's no way to go &quot;backward&quot; in this aircraft using the flight controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eYwFL.jpg&quot; alt=&quot;Piper Cherokee back seat&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Visibility aside, ground handling is often a a complex production, particularly for larger aircraft or when you have a lot of aircraft in proximity to each other or obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving small aircraft around typically requires at least 3 people. When you're moving forward you will have the person operating the tug and two &quot;wing walkers&quot; who stand a few feet off the wingtips and walk along to make sure the wings aren't going to hit anything. When pushing an aircraft back in a tightly packed hangar there's sometimes a fourth person walking ahead of the tail to make sure you don't back the plane into something.&lt;br&gt;&#xA;Since there's not usually much for the pilot to do inside the plane at this point, they usually serve as one of the walkers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger aircraft observe similar procedures, but for push-backs or power-backs it's known that the area behind the aircraft is clear (this is usually coordinated over the radio), and as long as the tug driver or pilot keeps the nosewheel on the appropriate pavement markings there will be wingtip clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Line personnel are also often stationed to &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_marshalling&quot; rel=&quot;noreferrer&quot;&gt;guide aircraft to and from parking&lt;/a&gt; in close quarters where positioning is critical (e.g. when pulling an airliner up to a gate, or parking a small aircraft on a busy ramp).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The other half of the picture is taxiing under your own power and control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When taxiing, it's generally assumed that the pilot knows their aircraft's dimensions and will avoid hitting things. This usually works out well, but &lt;a href=&quot;https://www.youtube.com/watch?v=ayCWSm1f9qk&quot; rel=&quot;noreferrer&quot;&gt;that is not always the case&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport taxiways are marked so an aircraft with a specific maximum wingspan will be clear of any obstacles while taxiing along the centerline, and as you're generally only going forward that's where visibility is most important (you can assume if the area your wingtip was going to hit was clear 15 seconds ago when you last saw it and nothing was heading into that area it's still clear now, and you're relying on the pilot of the aircraft behind you to be paying attention and not taxi into your tail).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1467" LastEditDate="2014-10-15T09:07:55.497" LastActivityDate="2014-10-15T09:07:55.497" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3320" PostTypeId="2" ParentId="3306" CreationDate="2014-04-10T20:28:48.710" Score="38" Body="&lt;p&gt;The pusher design is more efficient, because the suction forward of the prop reduces flow separation, and the accelerated flow behind it is not streaming around the fuselage (or wing), where it would create additional friction drag. In case of the Do-335 (see picture below), the single-engine top speed was 30 km/h higher with the rear engine running than with the front engine (both were DB-603s with identical power rating).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GXEJQ.jpg&quot; alt=&quot;Do-335&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the puller prop will help to maneuver the plane on the ground (this is a big benefit for taildraggers - note how many two-engined, taildragger airplanes have an &lt;a href=&quot;https://en.wikipedia.org/wiki/Twin_tail&quot; rel=&quot;nofollow noreferrer&quot;&gt;H-tail&lt;/a&gt; (two rudders as endplates of the stabilizer). They were placed in the prop wake and this gave much better directional control at low speed on the ground. Also, the prop wash helps to increase the lift from flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantage for a single-engined aircraft, the reduced tail clearance, has already been mentioned. If you cannot really rotate, takeoffs and landings are high-speed affairs. But there is another disadvantage to a rear-mounted prop: It stabilizes the aircraft, much as an additional tail, but without control surfaces.  Especially for a fighter aircraft, this is the opposite of what you want. THAT is why almost all high-powered, singe-engined aircraft have their propeller in the front: Maneuverability!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stabilizing effect increases in proportion to the propeller surface area and the thrust, of course. Since a regular airplane needs to have basic stability with the engine running at idle, any additional stability change due to propeller placement comes on top. At full power and with the long lever arm of a single pusher prop on a central fuselage (think &lt;a href=&quot;https://aviation.stackexchange.com/questions/34899/has-a-fixed-wing-aircraft-ever-been-built-that-featured-multiple-turbines-poweri/34903#34903&quot;&gt;LearAvia Learfan&lt;/a&gt;), the aircraft becomes stiff as a brick. A two-boom layout (think &lt;a href=&quot;https://en.wikipedia.org/wiki/SAAB_21&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab J 21&lt;/a&gt;, pictured below) is better, but creates additional friction and interference drag, so the advantage of the pusher arrangement is reduced. Note, however, that studies of a tractor engine variant (Saab J 23) showed inferior performance to the pusher design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PuI3K.jpg&quot; alt=&quot;Saab-21&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want hard data on that: There is an old &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1952/naca-tn-2585.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA report (NACA TN 2586)&lt;/a&gt; on this by John L. Crigler and Jean Gilman, called Propellers in Pitch and Yaw.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-08T17:08:49.467" LastActivityDate="2020-04-08T17:08:49.467" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="3321" PostTypeId="1" AcceptedAnswerId="3324" CreationDate="2014-04-11T03:40:58.397" Score="15" ViewCount="3237" Body="&lt;p&gt;In the olden days there used to be a navigation officer in commercial airlines who had the tasks of navigation and radio communication. But, in modern commercial airliners there is no navigation officer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do the pilot(s) take the additional responsibility of radio communication and navigation? Or is the navigation part now done by onboard computers and systems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the electronic navigation system fails, are there any backup plans? Are physical maps and a compass then used to determine the direction and position?&lt;/p&gt;&#xA;" OwnerUserId="1337" LastEditorUserId="3504" LastEditDate="2015-03-23T11:37:06.610" LastActivityDate="2018-01-08T17:27:28.847" Title="Why do we no longer have a navigation officer on modern commercial flights?" Tags="&lt;radio-communications&gt;&lt;navigation&gt;&lt;commercial-aviation&gt;&lt;crew&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3322" PostTypeId="1" AcceptedAnswerId="3336" CreationDate="2014-04-11T03:50:18.277" Score="7" ViewCount="2781" Body="&lt;p&gt;Let’s say you’re in class G and doing some aerobatics. Is there any standard frequency you might use (perhaps MULTICOM on 122.9?) to communicate your intentions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume you’re not using flight following and that you’re VFR.&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="1696" LastEditDate="2015-02-18T19:01:42.907" LastActivityDate="2015-06-24T11:19:58.043" Title="Is there a general radio frequency in Class G for broadcasting intentions?" Tags="&lt;radio-communications&gt;&lt;usa&gt;&lt;visual-flight-rules&gt;&lt;class-g-airspace&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3323" PostTypeId="2" ParentId="3316" CreationDate="2014-04-11T05:02:17.913" Score="7" Body="&lt;p&gt;Large planes generally have quite good visibility. In a document A319/A320/A321 Flight Deck and Systems Briefing for Pilots (can be found in many places on the net, e.g. &lt;a href=&quot;http://www.slideshare.net/FernandoNobre1/a319-320-321-flight-deck-and-systems-briefing-for-pilots&quot; rel=&quot;noreferrer&quot;&gt;on slideshare as presentation&lt;/a&gt;), or page 16 Airbus shows following diagram of visibility from cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PEXo4.jpg&quot; alt=&quot;A319/A320/A321 flight deck - pilot&amp;#39;s field of view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;20 degrees below horizon straight ahead is probably better than most single-engine GA aircraft with large engine cowling in front of the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-04-11T05:02:17.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3324" PostTypeId="2" ParentId="3321" CreationDate="2014-04-11T07:04:46.907" Score="21" Body="&lt;p&gt;Navigation has gotten much simpler over the years.  Initially, navigation would be done by a combination of dead reckoning, looking out the window for landmarks, and for night or long-distance flights, by celestial navigation (many old airplanes have a window at the navigator's station specifically to let the navigator see the stars).  This took quite a bit of time and effort, so the pilot couldn't do it and also fly the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1920s, radio navigation was added to the navigator's toolkit, but finding bearings to beacons and calculating a location was still an entirely manual process.  Additionally, radio beacons didn't cover the entire world, so older navigation techniques were still needed for most flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1950s, fully-automatic radio direction finding systems became common and navigation beacons were available across most of Europe and North America.  At this point, the workload involved in navigation dropped to the point that the pilot could also navigate: plot out the sequence of NDBs to follow ahead of time, then tune the radio and follow the navigation display.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very recently, navigation has been integrated with the autopilot to the point that the pilot can punch in a sequence of waypoints and have the airplane fly the route entirely on its own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, even today if the electronic navigation system fails, the fallback is map, compass, and slide rule.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-04-11T07:04:46.907" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3325" PostTypeId="2" ParentId="2437" CreationDate="2014-04-11T07:52:55.443" Score="7" Body="&lt;p&gt;My answer is: It depends. As always.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, yes, it is possible to land an aircraft on water intact. But the aircraft has to help you with that. If the engines are &lt;strong&gt;not&lt;/strong&gt; below the wings (turboprop, piston, jet at the rear fuselage), and the pilot flares to minimum speed right above the water, gear &lt;strong&gt;up&lt;/strong&gt;, then most aircraft will stay intact. Many are even tested for ditching qualities during development. I personally know of the ditching tests of the Breguet Atlantique and the Antonov-70, and there are certainly more (see &lt;a href=&quot;https://www.youtube.com/watch?v=jK8ydLY5QHQ&quot;&gt;https://www.youtube.com/watch?v=jK8ydLY5QHQ&lt;/a&gt; at 2:15 min into the movie).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Dutch Atlantique once had to go down and landed intact in the North Sea. It was towed into a harbor and lifted out of the water a few days later. The openings (for cooling air etc) have special valves which close automatically when the aircraft is in the water, much like a snorkel on a submarine (sorry, could not find a web source for this).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-11T07:52:55.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3326" PostTypeId="2" ParentId="3312" CreationDate="2014-04-11T10:11:07.183" Score="8" Body="&lt;p&gt;I found the following rather surprising statement in a (probably quite old) University of Southamption &lt;a href=&quot;http://www.southampton.ac.uk/%7Ejps7/Aircraft%20Design%20Resources/Powerplant/development%20of%20gas%20turbines.doc&quot; rel=&quot;noreferrer&quot;&gt;document&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Rolls-Royce has never had a service failure of conventional fan blades in over 40 million hours of operation, and there have been no service failures of wide-chord blades in over 10 million hours of operation (Baldwin 1993).&lt;/p&gt;&#xA;&lt;p&gt;In one incident, RB211-535E4 engines on a Boeing 757 were struck by a flock of Canada geese near Chicago – some seven birds, each around 3 kg, were ingested.  The wide-chord fan blades withstood the impact, which was some eight times greater than the requirements for certification, and the engine did not have to be shut down in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So far as I know, bodies like the NTSB don't collect statistics on blade failure events.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-11T10:11:07.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3328" PostTypeId="2" ParentId="2777" CreationDate="2014-04-11T13:28:14.973" Score="2" Body="&lt;p&gt;An (in)famous example would be John Denver's crash in an experimental aircraft, costing him his life.&lt;br/&gt;&#xA;Due to the placement of the fueltank selector, which was different from usual, he inadvertently selected an empty tank, causing him to eventually crash as his engine failed from fuel starvation at low altitude.&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.avweb.com/news/safety/183015-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;http://www.avweb.com/news/safety/183015-1.html?redirected=1&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-04-11T13:28:14.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3329" PostTypeId="1" AcceptedAnswerId="3330" CreationDate="2014-04-11T14:01:45.720" Score="8" ViewCount="1016" Body="&lt;p&gt;Is it possible to control the direction during auto-rotation, and how does it work?&lt;/p&gt;&#xA;" OwnerUserId="2089" LastEditorUserId="2089" LastEditDate="2014-04-11T14:07:33.010" LastActivityDate="2014-04-12T16:16:09.137" Title="Is it possible to control the direction during auto-rotation?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3330" PostTypeId="2" ParentId="3329" CreationDate="2014-04-11T14:17:39.813" Score="11" Body="&lt;p&gt;It's entirely possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Attitude control works the same way during autorotation as it does during normal powered flight. It's a good thing, too... during an autorotation you want to target your descent toward a suitable landing spot :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To (say) roll right, moving the cyclic causes the swashplate to move in such a way that the rotor blade's pitch (angle of attack) is greater during the left-side portion of the blade's travel, and lower during the right-side portion. This produces more lift on the left side, which causes a right-rolling moment on the helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that the collective is all the way down and that the rotor's RPM is being maintained by airflow through the rotor does not change the way the cyclic produces attitude changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The anti-torque pedals still work too, although during an autorotation the pilot will promptly apply full right pedal, since lowering the collective will essentially eliminate torque from the rotor. Pedals can still be used for yaw though, as the tail rotor is still spinning (it is linked to the main rotor).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;180° turning autorotation&quot; is a common maneuver taught in basic training, where the pilot must set up the autorotative descent and then complete a 180° turn toward a landing spot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information about autorotations in general, I recommend the FAA's (free online) &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/&quot; rel=&quot;nofollow&quot;&gt;Helicopter Flying Handbook&lt;/a&gt;. See page 2-24 for a general description, and page 11-2 for procedures/technique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also lots of autorotation demonstration videos on &lt;a href=&quot;http://www.youtube.com/&quot; rel=&quot;nofollow&quot;&gt;YouTube&lt;/a&gt; that show maneuvering to a landing spot / 180° turns during the auto.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-12T16:16:09.137" LastActivityDate="2014-04-12T16:16:09.137" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3331" PostTypeId="2" ParentId="3322" CreationDate="2014-04-11T14:42:15.627" Score="7" Body="&lt;p&gt;I'm not aware of any regulation or AIM entry that specifies what frequency to be on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I use the UNICOM frequency of the nearest airport when I'm out looping because I consider it to be the frequency most likely to be used by traffic near me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also has a mild safety benefit -- if something on my plane were to break, I'd already be on the right frequency for the airport I'm about to inhabit.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-04-11T14:42:15.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3332" PostTypeId="2" ParentId="2437" CreationDate="2014-04-11T17:20:52.210" Score="2" Body="&lt;p&gt;It would be judged upon the state of the aircraft once stopped after the collision, taking into account velocity and angle of impact etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the A/C is in-tact and no water is taken on-board it will float for a greater time but I highly doubt it will for a large amount of time because water always finds entry points.&lt;/p&gt;&#xA;" OwnerUserId="2092" LastActivityDate="2014-04-11T17:20:52.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3333" PostTypeId="1" CreationDate="2014-04-11T18:25:41.883" Score="16" ViewCount="2112" Body="&lt;p&gt;As I understand, there are two black boxes on-board an aircraft. One black box, the Cockpit Voice Recorder holds the cockpit conversations and the other, the Flight Data Recorder holds essential flight parameters.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;But why are the two black boxes holding &lt;strong&gt;separate&lt;/strong&gt; data?&lt;/li&gt;&#xA;&lt;li&gt;Why don't both black boxes hold copies of &lt;strong&gt;both&lt;/strong&gt; the FDR and the CVR data for extra redundancy in case the other box goes missing or is completely damaged by the crash?&lt;/li&gt;&#xA;&lt;li&gt;Are there any technical reasons for why this isn't possible or hasn't been attempted yet?&lt;/li&gt;&#xA;&lt;li&gt;Is there any benefit of having the CVR and FDR in separate boxes?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="504" LastEditorUserId="65" LastEditDate="2014-04-11T21:15:50.337" LastActivityDate="2020-05-14T19:15:09.107" Title="Why don't both black boxes hold the same data?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;flight-instruments&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3334" PostTypeId="2" ParentId="3333" CreationDate="2014-04-11T18:58:07.983" Score="4" Body="&lt;p&gt;There are a couple of reasons that I can think of off of the top of my head:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;There are different regulations covering when each of the boxes is required.  Some aircraft only require a CVR while others require both.  With them in different boxes, they can be installed in whatever combination is necessary.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They require connections to different systems in the aircraft, and requiring them both to connect to all systems would result in quite a bit of additional wiring.  It would also expose each box to a potential catastrophic electrical event (voltage spike) from any of the connected systems, potentially damaging both boxes at the same time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There is &lt;strong&gt;already&lt;/strong&gt; some added redundancy by them being in different boxes.  Even if one fails or is is badly damaged, there would probably be data available on the other one anyway.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;As Farhan pointed out, there are already some units capable of recording all data at once, but since the regulations only require one unit there is no added redundancy.  For aircraft that are required to have both a CVR amd a FDR it could be a great option!&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-12T04:22:48.500" LastActivityDate="2014-04-12T04:22:48.500" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3335" PostTypeId="2" ParentId="3333" CreationDate="2014-04-11T19:06:03.437" Score="3" Body="&lt;p&gt;Similar to Lnafziger, here is what I can think of:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Protecting two recorders in one box would be harder than protecting one recorder. The smaller the container, the easier it is to crashproof it.&lt;/li&gt;&#xA;&lt;li&gt;Adding a second recorder in each box adds complexity, which is not desirable in a system like this.&lt;/li&gt;&#xA;&lt;li&gt;Wiring up all of the data to both recorders would add complexity to the airplane, which is also not desirable.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The number of cases where your suggestion would actually benefit investigation is not very many. In crashes that damage the recorders too much, making the recorders larger and more complex would probably not help. There &lt;em&gt;have&lt;/em&gt; been many cases where the recorders didn't work properly or at all, so giving more functions to each box makes this more likely to occur more often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders&quot; rel=&quot;nofollow&quot;&gt;list of unrecovered flight recorders&lt;/a&gt;. Considering the time it spans, there are not many, and in some cases, neither recorder was recovered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll see if I can find any references for the cases where they were recovered but contained no useful data.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-11T19:20:21.133" LastActivityDate="2014-04-11T19:20:21.133" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3336" PostTypeId="2" ParentId="3322" CreationDate="2014-04-11T19:07:39.983" Score="6" Body="&lt;p&gt;MULTICOM is used when operating in the vicinity of an airport that has no tower, no FSS, and no UNICOM so wouldn't be appropriate here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an air-to-air frequency (122.75) but most pilots don't monitor it unless they have a specific reason to (i.e. someone else that they want to talk to).&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can listen to the closest airport or approach control frequency, but that would only help if the other aircraft is on the same frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, there isn't a good option for this, and in my opinion, unless you have a spotter watching for traffic in the area it would be pretty hard to do safely since it will be very hard for you to watch the area for traffic while doing aerobatics.  Other pilots may also have a hard time spotting you because you could be approaching from odd angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can get flight following, I would highly recommend it, but there is an even better option:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practice in an Aerobatic Practice Area.  See &lt;a href=&quot;https://aviation.stackexchange.com/questions/1937/where-do-airshow-pilots-practice&quot;&gt;Where Do Airshow Pilots Practice?&lt;/a&gt; for more specifics on this.  Not only would ATC and airports in the area know where you were, but a NOTAM is issued any time that it is active to warn pilots transitioning the area.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; See &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0401.html&quot;&gt;Services Available To Pilots&lt;/a&gt; for more details on communication frequencies.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-11T19:07:39.983" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3337" PostTypeId="2" ParentId="3333" CreationDate="2014-04-11T19:24:41.160" Score="2" Body="&lt;p&gt;In my opinion, &lt;strong&gt;I think that whatever is present in one black box also will often tell the other half of the story as well&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if the airspeed indicators are unreliable, the CVR will pick it up by the pilot's talking, even if the FDR may be lost or destroyed, which will point investigators in the right direction how to continue the investigation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, I'd imagine there's a bit of indirect redundancy by two devices. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, many aircraft have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Quick_access_recorder&quot; rel=&quot;nofollow&quot;&gt;quick access recorder&lt;/a&gt; which although not armoured will give much the same stuff as a FDR. If I'm not wrong, Flight Data Recorders are mostly non-mechanical devices and are tested annually, so they are kept reliable.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-04-12T09:11:26.880" LastActivityDate="2014-04-12T09:11:26.880" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3338" PostTypeId="2" ParentId="3333" CreationDate="2014-04-11T20:58:39.393" Score="10" Body="&lt;p&gt;Black Box(s) is a misnomer, you have correctly mentioned their actual names.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why are the two black boxes holding separate data?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;They have different purposes.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight data recorder:&lt;/strong&gt; This is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cockpit voice recorder:&lt;/strong&gt; This device is used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why don't black boxes hold copies of both the FDR and the CVR data for&#xA;  extra redundancy?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since they record different data, they are different. They are built different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Differences:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;FDR&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Time recorded: 25 hour continuous&lt;/li&gt;&#xA;&lt;li&gt;Number of parameters: 5 - 300+&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;CVR&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Time recorded: 30 min continuous, 2 hours for solid state digital units&lt;/li&gt;&#xA;&lt;li&gt;Number of channels: 4&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Similarities:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Impact tolerance: 3400 Gs /6.5ms&lt;/li&gt;&#xA;&lt;li&gt;Fire resistance: 1100 deg C /30 min&lt;/li&gt;&#xA;&lt;li&gt;Water pressure resistance: submerged 20,000 ft&lt;/li&gt;&#xA;&lt;li&gt;Underwater locator beacon: 37.5 KHz&lt;/li&gt;&#xA;&lt;li&gt;Battery: 6yr shelf life, 30 day operation&lt;/li&gt;&#xA;&lt;li&gt;Both recorders are installed in the most crash survivable part of the aircraft, usually the tail section.&lt;/li&gt;&#xA;&lt;li&gt;Each recorder is equipped with an &lt;a href=&quot;http://en.wikipedia.org/wiki/Underwater_locator_beacon&quot; rel=&quot;noreferrer&quot;&gt;Underwater Locator Beacon (ULB) or pinger&lt;/a&gt; to assist in locating in the event of an over water accident.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any technical reasons for why this isn't possible or hasn't&#xA;  been attempted yet?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It has certainly been &lt;a href=&quot;http://www.uasc.com/products/cvfdr.aspx&quot; rel=&quot;noreferrer&quot;&gt;attempted&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YLOSt.jpg&quot; alt=&quot;CVFDR&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there any benefit of having the CVR and FDR in separate boxes?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Probably the reason is that different teams investigate the data obtained from them as they have to recreate the scenario before the accident.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Regulatory Details&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CVR:&lt;/strong&gt; Due to the highly sensitive nature of the verbal communications inside the cockpit, Congress has required that the Safety Board not release any part of a CVR tape recording. Because of this sensitivity, a high degree of security is provided for the CVR tape and its transcript. The content and timing of release of the written transcript are strictly regulated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FDR:&lt;/strong&gt; Newly manufactured aircraft must monitor at least twenty eight important parameters such as time, altitude, airspeed, heading, and aircraft attitude. In addition, some FDRs can record the status of more than 300 other in-flight characteristics that can aid in the investigation. The items monitored can be anything from flap position to auto-pilot mode or even smoke alarms. &lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-04-11T20:58:39.393" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3339" PostTypeId="1" AcceptedAnswerId="3340" CreationDate="2014-04-11T21:50:08.163" Score="1" ViewCount="1080" Body="&lt;p&gt;Inspired by &lt;a href=&quot;https://aviation.stackexchange.com/questions/3329/is-it-possible-to-control-the-direction-during-auto-rotation&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My knowledge concerning helicopters is quite limited:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;what is auto-rotation? &lt;/li&gt;&#xA;&lt;li&gt;are there other &quot;rotations&quot; possible?&lt;/li&gt;&#xA;&lt;li&gt;in what do they differ?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-23T12:56:31.673" Title="What is auto-rotation?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-04-12T04:10:19.640" ContentLicense="CC BY-SA 3.0" />
  <row Id="3340" PostTypeId="2" ParentId="3339" CreationDate="2014-04-11T22:04:12.530" Score="1" Body="&lt;p&gt;When a helicopter engine fails, the pilot lets the rotor blade rotate freely pushed by the wind as the helicopter is falling out of the sky. This is called auto-rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal rotation is with the engine powering the rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important goal of auto-rotation is to get enough lift right before touch down by flaring so the landing is not a crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would also enter into autorotation when the tail rotor becomes ineffective and you can't recover it otherwise.  Once the tail rotor is back into action you can drive the rotor again.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="6919" LastEditDate="2015-03-23T12:56:31.673" LastActivityDate="2015-03-23T12:56:31.673" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3341" PostTypeId="2" ParentId="3261" CreationDate="2014-04-12T14:14:20.290" Score="3" Body="&lt;p&gt;There are many procedures and systems in place to reduce the risk of runway incursions as much as possible. Here's an outline of some of the areas where these are being applied:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Communication&lt;/li&gt;&#xA;&lt;li&gt;Airfield visual aids&lt;/li&gt;&#xA;&lt;li&gt;Airfield geometry&lt;/li&gt;&#xA;&lt;li&gt;Pilot, ATC and airport personnel training&lt;/li&gt;&#xA;&lt;li&gt;Surface movement guidance systems&lt;/li&gt;&#xA;&lt;li&gt;Airport procedures, and specially Low Visibility Procedures&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/151.pdf&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol&lt;/a&gt;, the majority of runway incursions happen due to communication breakdown, ground navigation errors due to inadequate or ambiguous surface signs and markings and relevant information needed in the cockpit, and occur during &#xA;taxiing out and departure operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find statistics for runway incursion incidents &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/statistics/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; from FAA, and &lt;a href=&quot;http://www.skybrary.aero/index.php/Runway_Excursion_Statistics_for_Europe&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; for Europe.&lt;/p&gt;&#xA;" OwnerUserId="1128" LastEditorUserId="1128" LastEditDate="2014-04-15T11:10:30.920" LastActivityDate="2014-04-15T11:10:30.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3343" PostTypeId="1" CreationDate="2014-04-12T16:36:02.533" Score="13" ViewCount="1805" Body="&lt;p&gt;Meaning by &quot;atmospheric geostationary satellite&quot; a vehicle capable of hovering 30 km above Earth surface, hence insde atmosphere, for unlimited time, making use of air propellers, solar panels and batteries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much energy is needed to keep an object steady in air at 30 km above surface?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two possibilities: a plane-like vehicle, flying in circle, using wings to stay up; an helicopter-like vehicle, hovering.&lt;/p&gt;&#xA;" OwnerUserId="2106" OwnerDisplayName="jumpjack" LastEditorUserId="97" LastEditDate="2014-04-13T01:28:51.600" LastActivityDate="2016-08-23T07:40:25.287" Title="Is an &quot;atmospheric geostationary satellite&quot; feasible with current technology?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3344" PostTypeId="2" ParentId="3343" CreationDate="2014-04-12T21:46:55.503" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.theverge.com/2014/3/27/5555060/facebook-plans-to-bring-world-online-with-fleet-of-solar-powered-drones&quot; rel=&quot;nofollow noreferrer&quot;&gt;Facebook is considering building solar powered communication drones&lt;/a&gt;. According to the linked Verge story, they'd hover at 20 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wouldn't call these drones satellites, they're not in orbit. An orbit at that altitude would have a speed of nearly 8 km/s and the period of the orbit would be about an hour and a half. A low altitude orbital sat wouldn't hover stationary over a given location. You need to get up to about 36,000 kilometers before the sats slow down enough to match the earth's rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: adding an illustration to show how altitude affects radius of footprint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xbjrn.png&quot; alt=&quot;Footprint radius&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where r is radius of earth (6378 km) and a is altitude drone (either 20 or 30 km).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Footprint radius for low altitudes is approximated by r sin α where α is acos(r/(r+a))&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a drone at 20 km this comes a radius of 503 km, for a drone at 30 km, this comes to a radius of 616 km. (503/616)^2 is ~.668. Lowering drone to 20 km would give a footprint of about 2/3 the area.&lt;/p&gt;&#xA;" OwnerUserId="2099" OwnerDisplayName="HopDavid" LastEditorUserId="2099" LastEditDate="2014-04-14T20:13:03.023" LastActivityDate="2014-04-14T20:13:03.023" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3346" PostTypeId="2" ParentId="3343" CreationDate="2014-04-13T07:33:17.740" Score="7" Body="&lt;p&gt;In 2003 &lt;a href=&quot;http://www.nasa.gov/centers/dryden/history/pastprojects/Helios/&quot;&gt;NASA's Helios solar-powered aircraft&lt;/a&gt; made it up to 29.52 km (rounds up to 30 km!).  Alas, it broke up in flight, and I can find no reference of a follow on.  A plane would be more energy efficient than a helicopter, even a helicopter in forward motion, so I expect a plane is what you would see first.  The problem of storing energy and flying at night may be insurmountable.  (Perhaps beaming microwave energy to the aircraft?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could almost imagine a blimp or dirigible with propulsion to fight the wind, but it would be difficult to get much payload at that altitude, and the wind up there is &lt;em&gt;fast&lt;/em&gt;.  So, no way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't mind a long line that aircraft would have to avoid, a kite is another possibility, and would solve the problem of power for the payload at night.  There are pretty constant winds up there, so if you can get it up, you can imagine a kite flying for a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tethered balloon could in principle work as well, and would have more payload than a free balloon trying to fly against the wind.  However the balloon envelope would have to be strong, and therefore heavy, to withstand being held against the wind by the tether.  Even a balloon envelope only three times as thick as those designed for zero-wind conditions would result in no payload capacity at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The kite seems the most plausible, but that altitude is well beyond the current record of 5.7 km.  A series of kites along the line can help carry the mass of the tether.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of these things could be referred to as a &quot;satellite&quot;.&lt;/p&gt;&#xA;" OwnerUserId="554" LastEditorUserId="554" LastEditDate="2014-04-13T19:53:08.840" LastActivityDate="2014-04-13T19:53:08.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3347" PostTypeId="1" AcceptedAnswerId="3354" CreationDate="2014-04-13T10:04:55.110" Score="12" ViewCount="3907" Body="&lt;p&gt;Did all NASA flight crew recruits learn to fly when preparing for Space Shuttle missions? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the pilot — and I am guessing the commander, too — would be USAF / USN / USMC pilots, but what about the specialists, engineers, etc? Do these have to learn to fly a jet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was this flight training used to simply train all crew members on the effects of traveling in a rocket into space? Or did (do?) all crew members have to learn how to fly a &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop T-38&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These questions are based on documentaries I have watched where NASA uses the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-38&lt;/a&gt; for flight training. I have wondered about this for a long time and could never get a satisfactory answer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea if NASA still uses the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-38&lt;/a&gt;. Again, I am basing that on what I have seen and read.&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="15311" LastEditDate="2017-12-11T09:28:58.123" LastActivityDate="2017-12-11T09:28:58.123" Title="Does NASA use T-38's to train all crew members of a space flight as pilots?" Tags="&lt;flight-training&gt;&lt;nasa&gt;&lt;space-shuttle&gt;&lt;t-38&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3348" PostTypeId="2" ParentId="3343" CreationDate="2014-04-13T11:07:01.450" Score="19" Body="&lt;p&gt;Short answer: No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: Your &quot;unlimited time&quot; condition makes the short answer easy. If you need to go up for a limited time, and you have the liberty to choose the time of ascent and descent, the answer is: Possibly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, there are two ways of going up there: A balloon and an aircraft. A helicopter would be much less efficient, the tether of a balloon will be too heavy to lift, and you will see that even a glider-like aircraft will struggle to stay for some time at 30 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, atmospheric pressure at 30 km is 12 mbar, just 1.2% of what it is on the ground. So your aircraft has to go at some speed just to create enough lift. If we assume that you fly at Mach 0.5 to 0.6 (where high-lift airfoils and propellers can still operate), your dynamic pressure is that of a modern glider at low speed. The flight speed actually is between 150 and 180 m/s, however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's assume your aircraft has an L/D of 50. This translates into a power requirement just to stay aloft of 3 to 3.6 kW per ton of aircraft mass. Your propeller will have no more than 85% efficiency, and your engine will create some loss as well, so your installed power needs to be at least 4 kW per ton of aircraft mass. Since you fly at a glider's dynamic pressure, you will also have a glider-like wing loading of 30 kg/m². Per ton, your wing area is 33.3 m². To operate an air breathing engine at this altitude is a challenge, so I will assume solar electric propulsion. Let's be optimistic and we assume a solar constant of 1.4 kW/m² at this altitude, and you fly at moderate latitudes (say, 45°), so your solar panels can create (20% efficiency) 200 W per m² or 5.3 kW per ton of aircraft mass (assuming 80% of the wing is covered, the rest will have too much curvature). Of course, this is all valid only around noon, so if you want to stay overnight, even in summer there is not enough energy to keep the aircraft up for a longer time, even with very optimistic assumptions. You might want to assume batteries which can provide the power for the climb phase, so you take off in the middle of the night and arrive (with empty batteries) at altitude in the late morning. Then you might really stay there until 2 or 3 pm, when the lowering sun means that your solar panels will not provide enough power to stay up, let alone charge the batteries. And I have not even started to subtract the power for operating any equipment (which would be the reason to go up there in the first place, right?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To go with a lower wing loading means you will have a very delicate structure which cannot cope with the winds at 30 km and gust loading at lower altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This wind will also be a problem for any ballon. 20% of winds at 30 km are above 76 m/s (Mil Std. 210C), 5% are even above 98 m/s. One cubic meter of helium gives you 10 N of lift at sea level, but only 0.156 N at 30 km. To lift one ton of balloon up to 30 km, you will need 63,000 m³ of volume. This is a sphere with a diameter of 50 m! The wind forces to keep this thing tethered will need a strong and heavy tether, so without going into the details I think that a tethered balloon will be a challenge, to put it mildly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;Facebook drone&quot; articles are not serious, they are meant to create some P.R., and don't hold your breath for Internet delivered by drones anytime soon.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-07T11:41:10.297" LastActivityDate="2014-12-07T11:41:10.297" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3349" PostTypeId="2" ParentId="2999" CreationDate="2014-04-13T15:06:37.373" Score="1" Body="&lt;p&gt;&quot;Glideability&quot; is flight. A fixed wing aircraft that is controllable under power, is controllable without it. Some aircraft are specifically designed to be unstable in flight, such as the F-16, and F-117. in those cases computers assist to provide artificial stability; as long as the computers are working, the aircraft is still controllable without a functioning powerplant.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glide ratio varies significantly between fixed wing aircraft. Unpowered gliders are generally higher than 20/1, while many small planes see 17/1 or less. The space shuttle is 4.5/1. (Horizontal/Verticle)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glide efficiency is mostly a function of drag, &lt;strong&gt;not&lt;/strong&gt; weight. For example:  gliders sometimes carry water ballast to &lt;em&gt;increase&lt;/em&gt; weight, since higher weight results in higher glide speed. (The water is dumped to slow the aircraft before landing.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA publishes airmans manuals, and you can find a variety of other flight instruction manuals available online or at the local airport. Any Private Pilot or Sport Pilot manual will discuss the basic principles of flight in some detail, They usually make for very clear and easy reading. &lt;/p&gt;&#xA;" OwnerUserId="2098" LastActivityDate="2014-04-13T15:06:37.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3350" PostTypeId="1" AcceptedAnswerId="3353" CreationDate="2014-04-13T17:40:01.913" Score="6" ViewCount="4477" Body="&lt;p&gt;I will most definitely start a training for a glider pilot license at our local flight club. This of course requires a medical certification for pilots. The only concern I have, is my blood pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am an 18 year old male with an overall healthy condition. However the last few times I had a doctor's appointment, I had a somewhat high blood pressure (it was always between 150/70 - 180/85 mmHg). Online I haven't really found that much information about the limit of the blood pressure in order to still get the Medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have found some sources saying that everything below 220/125 is good, but I think those sources we're only speaking about passengers of airplanes, not pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your info: I live in Germany, and I suppose there are other regulations regarding the medical in other countries, but overall I think the requirements don't differ that much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully someone can tell me if I should be concerned or if my blood pressure is still okay to fly.&lt;/p&gt;&#xA;" OwnerUserId="2067" LastEditorUserId="14897" LastEditDate="2019-09-17T17:31:19.210" LastActivityDate="2019-09-17T17:31:19.210" Title="Will high blood pressure affect my pilot medical certification?" Tags="&lt;flight-training&gt;&lt;medical&gt;&lt;glider&gt;&lt;lba-regulations&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3351" PostTypeId="5" CreationDate="2014-04-13T17:59:49.217" Score="0" Body="&lt;p&gt;The Luftfahrt-Bundesamt (LBA, &quot;Federal Aviation Office&quot;) is the national civil aviation authority of Germany headquartered in Braunschweig. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The LBA is responsible for developing and maintaining aviation safety standards as well as certifying airlines, airports and training devices such a simulators and Flight Training Devices (FTDs). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of these tasks are fulfilled on behalf of the European Aviation Safety Agency (EASA). Investigation of accidents is not a responsibility of the LBA but of the German Federal Bureau of Aircraft Accidents Investigation.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Office_for_Civil_Aviation_of_Germany&quot; rel=&quot;nofollow&quot;&gt;Luftfahrt-Bundesamt (Wikipedia)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.lba.de/EN/Home/homepage_node.html&quot; rel=&quot;nofollow&quot;&gt;Website (English)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2015-06-23T09:32:44.577" LastActivityDate="2015-06-23T09:32:44.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3352" PostTypeId="4" CreationDate="2014-04-13T17:59:49.217" Score="0" Body="The LBA is responsible for developing and maintaining aviation safety standards, as well as certifying airlines, airports and training devices such a simulators and Flight Training Devices (FTDs).  " OwnerUserId="69" LastEditorUserId="8547" LastEditDate="2015-06-23T13:08:45.913" LastActivityDate="2015-06-23T13:08:45.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3353" PostTypeId="2" ParentId="3350" CreationDate="2014-04-13T18:55:48.333" Score="3" Body="&lt;p&gt;Without knowing German, it's a little difficult for me to research the &lt;a href=&quot;http://www.lba.de/&quot; rel=&quot;nofollow&quot;&gt;LBV's website&lt;/a&gt;, but I found this application for &lt;a href=&quot;http://www.lba.de/SharedDocs/Downloads/Formulare/L4/L4_Auslaendische/L1_L1005-01-06.html&quot; rel=&quot;nofollow&quot;&gt;Validation of a foreign airman’s licence&lt;/a&gt;, and one of the requirements in it is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Valid JAR-FCL Medical Class I or Class II &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.jaa.nl/publications/jars/606984.pdf&quot; rel=&quot;nofollow&quot;&gt;JAR requirements&lt;/a&gt; for a Class I and Class II medical, both are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;JAR–FCL 3.135 Cardiovascular system – Blood pressure&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The blood pressure shall be recorded with  the technique given in&#xA;  paragraph 3 Appendix 1 to  Subpart B [at each examination]. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) When the blood pressure at examination  consistently exceeds 160&#xA;  mmHg systolic and/or  95 mmHg diastolic, with or without treatment,&#xA;  the  applicant shall be assessed as unfit. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Treatment for the control of blood  pressure shall be compatible&#xA;  with the safe exercise  of the privileges of the applicable licence(s)&#xA;  and be  compliant with paragraph 4 Appendix 1 to Subpart &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;B. The initiation of [ ][medication] shall require a  period of&#xA;  temporary suspension of the medical  certificate to establish the&#xA;  absence of significant  side effects. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Applicants with symptomatic hypotension  shall be assessed as&#xA;  unfit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like you will probably need to lower your blood pressure (either via diet and exercise or with medication) in order to pass your medical.  If you start taking blood pressure medication, you will need to take it for a certain period of time to make sure that there are no other side effects before they will give you a medical.  You can discuss this with a medical examiner to see how the process works there.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-13T18:55:48.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3354" PostTypeId="2" ParentId="3347" CreationDate="2014-04-13T20:19:35.017" Score="17" Body="&lt;p&gt;Non-pilot astronauts are not required to become pilots. They fly in the backseat of T-38's partially for transportation purposes, and partially for flight regime training. They are called &quot;mission specialists&quot; and since their job does not require piloting skills, there is no reason to train them as such.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/johnson/pdf/606877main_FS-2011-11-057-JSC-astro_trng.pdf&quot;&gt;NASA literature&lt;/a&gt; says &lt;em&gt;&quot;The T38 is used for&#xA;flight readiness training to help the astronauts become adjusted to&#xA;the flight environment, including the g-forces experienced on launch&quot;&lt;/em&gt; and that non-pilots fly at least four hours per month in a T-38. Pilot astronauts fly at least 15 hours per month to maintain proficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can look up whether someone has a US Pilot's license using the FAA's &lt;a href=&quot;https://amsrvs.registry.faa.gov/airmeninquiry/&quot;&gt;Airmen Inquiry Page&lt;/a&gt;. A quick search turns up several astronauts who have never been licensed. For example, the mission specialists on the final shuttle mission, &lt;a href=&quot;http://en.wikipedia.org/wiki/Sandra_Magnus&quot;&gt;Sandra Magnus&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Rex_Walheim&quot;&gt;Rex Walheim&lt;/a&gt;, are not pilots. That being said, I wouldn't be surprised if most, if not all, of the non-pilot astronauts got some stick time in a T-38 since it is a trainer with dual controls.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Obviously the pilot and I'm guessing the commander would be airforce pilots&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the NASA vocabulary, &lt;em&gt;commander&lt;/em&gt; is equivalent to what you would think of as pilot or captain, whereas &lt;em&gt;pilot&lt;/em&gt; is equivalent to what you would think of as co-pilot. In the Apollo program, the commander landed the lunar module on the moon, not the &quot;Lunar Module Pilot,&quot; and in the shuttle program, the commander landed the shuttle, not the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, you are correct that both the commander and pilot must be pilots, and some of them did come from the Air Force, although US Navy was more common, and a few came from the Marine Corps. Almost all of them were test pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few astronauts joined NASA with the qualifications to be pilot-astronauts, but only flew as mission specialists (for example, &lt;a href=&quot;http://en.wikipedia.org/wiki/James_S._Voss&quot;&gt;James Voss&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Carl_J._Meade&quot;&gt;Carl J. Meade&lt;/a&gt;). I am honestly not sure whether or not NASA allowed them to fly the T-38's; however, the only photo evidence I can find shows them in the rear seat, which leads me to believe they were not allowed to fly solo.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have no idea if NASA still uses T-38's&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;NASA does still use T-38's because NASA still sees a need for pilot astronauts in the future, and the pilots need a way to maintain flying proficiency. In the &lt;a href=&quot;http://www.nasa.gov/astronauts/2013astroclass.html#.U0rlXPldWWc&quot;&gt;2013 Astronaut Candidate Class&lt;/a&gt;, four out of the eight were test pilots of some sort, although it's unclear how many will be considered pilot-astronauts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is &lt;a href=&quot;http://www.local8now.com/news/headlines/NASA-jet-to-go-on-display-at-Bowling-Green-Ky-park-251738831.html&quot;&gt;anecdotal evidence&lt;/a&gt; that the number of T-38's which NASA operates does appear to be shrinking, which is likely a reflection of a reduced astronaut corps size, budget constraints, and the fact that the aircraft fleet is about 50 years old. According to unconfirmed sources (&lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot;&gt;wikipedia&lt;/a&gt;), the number of NASA T-38's is expected to be reduced from 32 to 16 by 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other Space Shuttle-specific aircraft have been retired entirely, such as the Gulfstream II &lt;a href=&quot;http://en.wikipedia.org/wiki/Shuttle_Training_Aircraft&quot;&gt;Shuttle Training Aircraft&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft&quot;&gt;Shuttle Carrier Aircraft&lt;/a&gt; (the latter wasn't flown by astronauts).&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2014-04-13T20:19:35.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3355" PostTypeId="1" CreationDate="2014-04-14T02:28:33.257" Score="5" ViewCount="573" Body="&lt;p&gt;If a pilot is unable to act as PIC because they need a flight review, can they instead earn WINGS credits and complete a phase? Everything I have read, including §61.56 and &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2061-91J.pdf&quot;&gt;AC 61-91J&lt;/a&gt;, suggests that the answer is &quot;yes&quot;, but apparently nobody else is discussing it because I can't seem to find the answer on the internet. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-04-15T16:33:21.120" Title="How thoroughly can WINGS phases substitute for a flight review?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;&lt;faa-wings-program&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3356" PostTypeId="1" AcceptedAnswerId="3357" CreationDate="2014-04-14T02:29:45.113" Score="11" ViewCount="2234" Body="&lt;p&gt;There are two main types of supplemental oxygen devices in light aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Cannula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YYXR9.jpg&quot; alt=&quot;Precise Flight standard cannula&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Oxygen mask:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ptevo.jpg&quot; alt=&quot;Precise Flight microphone mask&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What are the major differences between these two devices? Is one more suitable for specific siutations than another, or is it just a matter of personal preference?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="65" LastEditDate="2015-03-20T20:07:13.883" LastActivityDate="2016-09-30T16:56:48.563" Title="For supplemental oxygen, what is preferred between masks and cannulas?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;equipment&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3357" PostTypeId="2" ParentId="3356" CreationDate="2014-04-14T02:41:02.317" Score="11" Body="&lt;p&gt;Cannulas are not effective above medium altitudes, and the FAA prohibits their use above 18,000 feet (FAA brochure on &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf&quot;&gt;Oxygen Equipment&lt;/a&gt;, PDF). Because they only place oxygen at your nose, you don't receive oxygen when talking or breathing through your mouth, while a mask covers both nose &amp;amp; mouth. This is, obviously, not great.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cannulas are also less comfortable than a nice-quality mic/mask, but that's my personal opinion. A lot of pilots do prefer cannulas for comfort at lower altitudes, as they're easier to don and allow you to continue using your normal headset mic boom. For most pilots, especially those flying normally aspirated aircraft types, it's a matter of preference. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-04-14T17:35:55.937" LastActivityDate="2014-04-14T17:35:55.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3360" PostTypeId="1" AcceptedAnswerId="3361" CreationDate="2014-04-14T07:22:35.803" Score="29" ViewCount="9760" Body="&lt;p&gt;We may all be familiar with the part of the cabin safety briefing where they say that, in the event of a reduction in cabin pressure, oxygen masks will drop from a compartment above our heads, yadda yadda, the bag may not inflate. What is the purpose of the bag?&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="849" LastEditDate="2014-04-14T16:40:07.560" LastActivityDate="2014-04-14T17:50:01.567" Title="What is the bag for on a passenger oxygen mask?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;airliner&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3361" PostTypeId="2" ParentId="3360" CreationDate="2014-04-14T08:15:56.517" Score="35" Body="&lt;p&gt;Oxygen in passenger masks is either generated by oxygen generator or released from pressurized container via reduction valve. In either case it is released at fixed rate. But human breath is discontinous. So the bag acts as a buffer. You inhale the oxygen accumulated in it and then it slowly refills while you are exhaling.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-04-14T08:15:56.517" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3364" PostTypeId="2" ParentId="3360" CreationDate="2014-04-14T13:52:08.630" Score="9" Body="&lt;p&gt;In addition to what our friend Jan Hudec mentioned:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Emergency%5foxygen%5fsystem&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The mask may also have a concentrator or re-breather bag that may or&#xA;  may not inflate depending on the cabin altitude, which has (in some&#xA;  instances) made passengers nervous the mask was not providing adequate&#xA;  oxygen, causing some to remove them, who thereby suffered hypoxia.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Pilot-and-Passenger-Physiology/Oxygen-Use-in-Aviation.aspx&quot;&gt;AOPA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The partial rebreather is the most common. With these, there's an&#xA;  external plastic bag that inflates each time you exhale. The purpose&#xA;  of the bag is to store any unused oxygen, so that it can be inhaled&#xA;  with the next breath.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-04-14T13:52:08.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3365" PostTypeId="1" CreationDate="2014-04-14T15:40:20.777" Score="1" ViewCount="88" Body="&lt;p&gt;Can someone explain why the aircraft would fly in an arc using the satellite as a reference point? Have I missed something?&lt;/p&gt;&#xA;" OwnerUserId="2109" LastEditorUserId="22550" LastEditDate="2018-11-22T14:25:58.010" LastActivityDate="2018-11-22T14:25:58.010" Title="Flight path question? re missing 777 MH370" Tags="&lt;airliner&gt;&lt;navigation&gt;&lt;mh370-incident&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2014-04-14T16:40:52.090" ContentLicense="CC BY-SA 3.0" />
  <row Id="3366" PostTypeId="2" ParentId="3360" CreationDate="2014-04-14T17:40:16.617" Score="8" Body="&lt;p&gt;I can't actually track down the purpose of the bag; however, the FAA &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf&quot;&gt;Oxygen Equipment guide&lt;/a&gt; states that it is not for the purpose of mixing exhaled air with pure oxygen:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The phase-sequential continuous-flow mask looks similar to a general aviation re-breather. However, both masks function differently, and the phase sequential mask allows the user to go to higher altitudes. &lt;strong&gt;This mask uses a series of one-way ports that allow a mixture of 100% oxygen and cabin air into the mask. Exhalation is vented to the atmosphere; as a result, the bag does not inflate.&lt;/strong&gt; [&lt;em&gt;emphasis mine&lt;/em&gt;] This mask can be safely used at emergency altitudes up to 40,000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because of the construction, the bag seems to act as a buffer, as Jan Hudec states in his answer.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-04-14T17:50:01.567" LastActivityDate="2014-04-14T17:50:01.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3367" PostTypeId="1" AcceptedAnswerId="3368" CreationDate="2014-04-14T17:59:27.330" Score="46" ViewCount="10083" Body="&lt;p&gt;Today I flew on an Embraer 190 of Kenya Airways. Checking in the tech specs this aircraft has a range of roughly 2900 km. Considering it is built in Brasil, I was wondering how do they deliver it to Africa since they would have to cross the Atlantic Ocean which I suppose is more than 2900 kms of range it has available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they add temporary tanks and, of course, by flying the aircraft empty get more range out of it?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="-1" LastEditDate="2017-11-07T17:53:26.647" LastActivityDate="2017-11-07T19:38:27.610" Title="How do airliners get from the factory to the client if the aircraft does not have the required range?" Tags="&lt;airliner&gt;&lt;ferry-flight&gt;&lt;range&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3368" PostTypeId="2" ParentId="3367" CreationDate="2014-04-14T18:19:39.150" Score="41" Body="&lt;p&gt;Sometimes they do add temporary tanks. &lt;a href=&quot;http://www.airliners.net/photo/0148884/M/&quot; rel=&quot;noreferrer&quot;&gt;Here's a picture&lt;/a&gt; of what Hawaiian Airlines had to do to get their fleet of 717's over the Pacific because they did not have the range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have the answer to your question specifically, but I would guess they either add temporary tanks and go from &lt;a href=&quot;http://www.gcmap.com/mapui?P=sbnt-cky&amp;amp;R=2900km@sbnt%0D%0A&amp;amp;MS=wls&amp;amp;DU=km&quot; rel=&quot;noreferrer&quot;&gt;SBNT-GUCY&lt;/a&gt; which is not much further than max-range, or take the long haul through the US and Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a &lt;a href=&quot;http://crankyflier.com/2012/08/30/how-do-airlines-deliver-airplanes-long-distances-ask-cranky/&quot; rel=&quot;noreferrer&quot;&gt;Cranky Flier blog post&lt;/a&gt; about this.&lt;/p&gt;&#xA;" OwnerUserId="757" LastEditorUserId="946" LastEditDate="2017-06-20T14:59:58.490" LastActivityDate="2017-06-20T14:59:58.490" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3369" PostTypeId="2" ParentId="3367" CreationDate="2014-04-14T18:21:08.833" Score="27" Body="&lt;p&gt;First of all, yes, there are tricks to get the aircraft fly farther. You can leave the payload out, this will allow you to fill all fuel tanks without reaching the maximum take-off mass. Less mass means less induced drag, so you can fly higher and at a lower fuel flow. It will also allow you to install temporary tanks to carry even more fuel than the aircraft was designed for. That is how small GA aircraft get transferred from the US to Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ufDIa.png&quot; alt=&quot;This is a typical payload-range diagram with the three distinct points: Maximum payload, maximum fuel and transfer range with no payload.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a typical payload-range diagram with the three distinct points: Maximum payload, maximum fuel and transfer range with no payload. The slope between maximum payload and maximum fuel points shows how well the additional mass of fuel is converted into range (mostly due to engine efficiency), and the slope of the lower segment between maximum fuel and no payload shows how much the weight reduction increases range (due to induced drag reduction).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In jets and turboprops, you can use &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a178559.pdf&quot; rel=&quot;noreferrer&quot;&gt;higher-density fuel&lt;/a&gt; (PDF) which gives you more energy per volume in order to get a few more percent of range. And if all fails, you can disassemble the aircraft and ship or fly the parts over. If the range is not sufficient, the plane will be small enough and will be designed for easy dis- and reassembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rd2ai.jpg&quot; alt=&quot;Short Belfast being loaded with JetRanger&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short Belfast being loaded with JetRanger (own work)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-11-07T19:38:27.610" LastActivityDate="2017-11-07T19:38:27.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3370" PostTypeId="1" AcceptedAnswerId="3372" CreationDate="2014-04-14T21:20:06.183" Score="18" ViewCount="6832" Body="&lt;p&gt;It is normal to see older planes (20+ years) quite frequently. In fact, a few months ago I saw a plane over 50 years old (not in a museum but on a runway, about to take off).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing to cars, there are not many cars on the road which are older than 10-15 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the reasons for this besides the following?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Airplanes are very expensive. A new 172 would be over USD 300,000, and a thirty year old can be around \$50k or less.&lt;/li&gt;&#xA;&lt;li&gt;Airplanes follow a very strict maintenance schedule and are inspected thoroughly (ideally speaking). Hence their life is increased.&lt;/li&gt;&#xA;&lt;li&gt;Pilots are very well trained compared to car drivers, so they know a lot more of what they are doing. Hence they are more aware of the condition of the plane.&lt;/li&gt;&#xA;&lt;li&gt;Cars crash a lot more often than airplanes.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;It appears that this holds true for both general and commercial aviation.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="247" LastEditDate="2014-04-15T04:51:45.003" LastActivityDate="2021-03-01T13:18:08.423" Title="Why are older airplanes still in use?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;aircraft-maintenance&gt;&lt;airworthiness&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3371" PostTypeId="2" ParentId="2695" CreationDate="2014-04-15T00:10:54.410" Score="2" Body="&lt;p&gt;A major noise (and vibration) during the flight is the retraction and extension of the landing gear as well as the wheel brake on the wheels once the gear is fully retracted. The vibration is more noticeable (obviously) on aircraft with the main gear in the fuselage and if you are seated over the main gear. &lt;/p&gt;&#xA;" OwnerUserId="558" LastActivityDate="2014-04-15T00:10:54.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3372" PostTypeId="2" ParentId="3370" CreationDate="2014-04-15T00:11:16.733" Score="17" Body="&lt;p&gt;Besides the main points you mentioned, I can think of a couple things, the first is sort of related to your point #1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes are designed to be easy to service. Cars are less so.&#xA;Cars only have a few very expensive parts, mainly the drivetrain (engine and transmission). If either of those needs to be replaced in an older car, it can easily cost more than the car is worth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes are much more complex, and have a larger number of expensive components. The engines of most airliners are designed to be removed relatively quickly. Although the engines tend to be the most expensive part, replacing an engine is nowhere near the total cost of the airplane, and there is generally a good pool of engines out there for parts and replacement (just look at how many JT8D engines are still in service).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In GA aircraft, it is easier for a repair to cost more than the airplane is worth. However, the more comprehensive maintenance required on aircraft means that this kind of repair is less likely to be needed. Also, while its usually easy to go out and replace a broken car with a comparable new or used one, the aircraft market isn't as large. New aircraft tend to be much more expensive, and the used market is more limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is that airplanes can have more unique qualities than cars. For example, there are original 737s flying in Canada because they are able to operate from gravel runways. There are just more combinations of sizes and capabilities in airplanes than with cars. Many times, it is only economical to replace those aircraft (both for the builder and the buyer) in very long cycles.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-15T15:07:59.460" LastActivityDate="2014-04-15T15:07:59.460" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3373" PostTypeId="1" AcceptedAnswerId="3374" CreationDate="2014-04-15T01:04:25.527" Score="5" ViewCount="191" Body="&lt;p&gt;I've been looking at the data found in various type certificate data sheets and found something that is a bit ambiguous. In reading a TCDS (like &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e0f48f814ea3dd6486257bb20063ad44/$FILE/2A13_Rev_52.pdf&quot; rel=&quot;nofollow&quot;&gt;this one&lt;/a&gt;, for example) in the &quot;airspeed limits&quot; section it lists the maneuvering speed. But they don't make it clear whether they are referencing the design maneuvering speed (Va) or the Maximum operating maneuvering speed (Vo).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone clarify which one they are referencing?&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="1696" LastEditDate="2015-02-17T21:34:23.130" LastActivityDate="2015-02-17T21:34:23.130" Title="Which maneuvering speeds are included in the TCDS?" Tags="&lt;faa-regulations&gt;&lt;aircraft-performance&gt;&lt;airspeed&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3374" PostTypeId="2" ParentId="3373" CreationDate="2014-04-15T03:37:52.073" Score="4" Body="&lt;p&gt;The speeds that they list in your linked TCDS (along with their corresponding V speeds) are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Never exceed 171 mph (148 knots) CAS - V&lt;sub&gt;NE&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;Maximum structural cruising 140 mph (121 knots) CAS - V&lt;sub&gt;NO&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;Maneuvering 129 mph (112 knots) CAS - V&lt;sub&gt;A&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;Flaps Extended 115 mph (100 knots) CAS V&lt;sub&gt;FE&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For a list of these V Speeds along with their definitions, see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;SID=f553dbb9c06409a040f3d6865e435c70&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:1.0.1.1.1.0.1.2&amp;amp;idno=14;cc=ecfr&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.2&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-15T03:37:52.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3375" PostTypeId="2" ParentId="3370" CreationDate="2014-04-15T03:45:26.530" Score="11" Body="&lt;p&gt;I own a 182 from 1976 and it looks brand new.  It's a common misconception that planes don't oxidize; they do.  Aluminum does have it's own form of &quot;rust&quot;.  Airplanes that are on the coasts usually have a rust preventative applied frequently to prevent oxidizing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you have a problem with a car you take it to the shop.  This problem could have occurred in your driveway or on the road somewhere away from home.  My point here is that cars rarely see service unless there's an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airplanes, they need to have a yearly &quot;annual&quot;.  In which a licensed A&amp;amp;P will go over the plane and recommend fixes before the plane is deemed flight worthy again.  Also, an airplane engine has an end of life.  This end of life is somewhat debated in the pilot community as it seems from data collected on accident statistics that many engine failures increase shortly after an engine has been rebuilt. This is in addition to any squawks I may have throughout the year.  If something doesn't sound or feel right, it gets looked at.  I don't wait for a &quot;breakdown&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I trust my airplane and her engine 100%.&lt;/p&gt;&#xA;" OwnerUserId="2116" LastEditorUserId="-1" LastEditDate="2014-05-15T19:26:27.330" LastActivityDate="2014-05-15T19:26:27.330" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3376" PostTypeId="2" ParentId="3367" CreationDate="2014-04-15T03:49:51.257" Score="17" Body="&lt;p&gt;I flew in a brand spanking new Airbus A320 on its maiden voyage from Toulouse, France to New York about 13 years ago.  We had to stop in Iceland and Newfoundland for fuel before heading to New York.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At Oshkosh every year (EAA Airventure) I hear about pilots crossing from Africa (the furthest western point) to the furthest eastern point of Brazil in a single engine small plane.  So I'm betting the jet can easily make that crossing.  They do have to put down at the first airport to get fuel.  That flight is not one I'd care to do...&lt;/p&gt;&#xA;" OwnerUserId="2116" LastEditorUserId="97" LastEditDate="2014-04-18T04:41:10.820" LastActivityDate="2014-04-18T04:41:10.820" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3377" PostTypeId="2" ParentId="3355" CreationDate="2014-04-15T03:53:04.720" Score="1" Body="&lt;p&gt;Yes, but you still need a signoff from a CFI.  My group of friends (and my CFI) use wings.  I did that one year but I prefer flying the BFR because that's skill based.  I still do wings credit courses though; you can never learn too much.&lt;/p&gt;&#xA;" OwnerUserId="2116" LastActivityDate="2014-04-15T03:53:04.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3378" PostTypeId="1" AcceptedAnswerId="3389" CreationDate="2014-04-15T05:58:57.220" Score="22" ViewCount="2298" Body="&lt;p&gt;Following up on &lt;a href=&quot;https://aviation.stackexchange.com/questions/3039/are-pilots-allowed-to-let-passengers-fly-the-plane&quot;&gt;this question about pilots letting passengers fly the plane&lt;/a&gt;, suppose you’re in a Cessna 172 with passengers and you have your PPL. If you want to let a friend try flying the plane, you might climb to 3,000' AGL and get clear of other traffic. You’d probably get to $V_A$ or a little less and trim for level flight. Then, you might let them try some shallow turns. You’d probably say:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Don’t fight me on the controls&lt;/li&gt;&#xA;&lt;li&gt;If I say let go, let go immediately&lt;/li&gt;&#xA;&lt;li&gt;Don’t move any of the controls very rapidly&lt;/li&gt;&#xA;&lt;li&gt;Don’t move any of the controls to their limits&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What else might you say? Are these things correct? What else might you let them try?&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-04-16T13:16:03.930" Title="How would you brief passengers who will try flying your plane?" Tags="&lt;passenger&gt;&lt;ppl&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3380" PostTypeId="2" ParentId="3343" CreationDate="2014-04-15T07:19:10.563" Score="4" Body="&lt;p&gt;Depending on your definition of &quot;unlimited&quot; it is not only already possible but you can (or could) already buy it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Titan Aerospace introduced the Solara last year. It's a solar powered plane with an expected airborne time of 5 years. Obviously they haven't tested it for 5 years but worst case is that you'd have to land it every couple of years for maintenance. The target market is specifically atmospheric satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They had a web page up where you could order one. Last time I checked their website implied that they had 5 orders. They had a progress indicator of when you can expect to get your plane if you have several million dollars to spend and they said that it takes about a month to build one. When I checked they said the earliest you can expect it was 5 months away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately since Google bought the company the website's been down so there's nothing much on their site. But if you google &quot;Titan Solara&quot; you may see pictures of their plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an Arstechnica article about the Solara: &lt;a href=&quot;http://arstechnica.com/information-technology/2013/08/almost-orbital-solar-powered-drone-offered-as-atmospheric-satellite/&quot; rel=&quot;nofollow&quot;&gt;http://arstechnica.com/information-technology/2013/08/almost-orbital-solar-powered-drone-offered-as-atmospheric-satellite/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The Solara is designed to loiter around 20km up, not 30km.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastEditorUserId="2117" LastEditDate="2014-04-15T07:24:20.500" LastActivityDate="2014-04-15T07:24:20.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3382" PostTypeId="1" AcceptedAnswerId="3385" CreationDate="2014-04-15T09:17:21.840" Score="13" ViewCount="4900" Body="&lt;p&gt;Winglets are used to reduce induced drag on the main wings of an aircraft as per explanations on &lt;a href=&quot;http://en.wikipedia.org/wiki/Wingtip_device&quot;&gt;wikipedia&lt;/a&gt;. Since they are very effective I was wondering why they are not installed also on horizontal stabilizers. For sure there must be some sort of induced drag being generated on horizontal stabilizers too as they are cutting through the air just as the main wings do. So why aren't there any sort of &quot;minified&quot; winglets available as an aftermarket installation (or, at least, I haven't ever seen some myself)?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="6919" LastEditDate="2015-04-14T09:40:27.123" LastActivityDate="2015-05-07T20:21:32.990" Title="Why don't horizontal stabilizers have winglets?" Tags="&lt;winglets&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3383" PostTypeId="2" ParentId="3378" CreationDate="2014-04-15T09:28:09.747" Score="2" Body="&lt;p&gt;Besides the points you mentioned, on my introductory flight my instructor was very clear regarding shifting the commands from one person to the other on the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When handing over commands he told me to specify clearly with the words &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;Handing Over Commands&lt;/code&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;whenever I would feel uncomfortable or he would feel that he had to take back control. This was done to clearly mark who was handling the aircraft in order to avoid confusion and get into a situation where dangerous things could happen.&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2014-04-15T09:28:09.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3384" PostTypeId="2" ParentId="3382" CreationDate="2014-04-15T09:29:19.217" Score="3" Body="&lt;p&gt;The induced drag from wingtip vortexes is mostly on lift generating surfaces, horizontal stabilizers don't generate that much lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said there is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Twin_tail&quot; rel=&quot;nofollow&quot;&gt;twintail&lt;/a&gt; design with double vertical stabilizer at the ends of the horizontal one; but that is not for reducing vortexes but for improving rudder response.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-04-15T09:29:19.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3385" PostTypeId="2" ParentId="3382" CreationDate="2014-04-15T09:32:03.310" Score="16" Body="&lt;p&gt;Horizontal stabilizers don't generate as much pressure difference as the wings. Generally the stab deflections are very small in flight, and there's so much other drag during landing -- when the stab gets the most use -- that wing vortices from the tail are probably the least of your problems. Stabilizer winglets on their own, when there's no pressure difference, would simply result in drag, whereas the main wing winglets are constantly effective while flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, the weight and trouble of adding little winglets to the horizontal stabilizers with larger actuators and hinges, for example, would probably outweigh the very slight aerodynamic benefit. I could also imagine that since the airflow over latter part of the wing is complex and varied, find a good design solution would be difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @Federico points out, the DA42 has them, but that's a composite airframe rather than the metal construction you see in most Cessnas, for instance, where you have to be more conservative in construction. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="3504" LastEditDate="2015-01-18T16:08:27.610" LastActivityDate="2015-01-18T16:08:27.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3386" PostTypeId="1" CreationDate="2014-04-15T10:59:43.973" Score="5" ViewCount="272" Body="&lt;p&gt;&lt;em&gt;Here are a few thoughts:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;'Real' accidents happen much too seldom to be of any real measure, and they would have to be compensated for the number of passenger kilometers as well to be objective. Large airlines may have be involved in more accidents, but they have more aircraft. Many airlines low down on the reports had accidents many years ago.&lt;/li&gt;&#xA;&lt;li&gt;Avherald and the like may be good sources but emphasize that they don't report on all accidents.&lt;/li&gt;&#xA;&lt;li&gt;Different jurisdictions have different reporting requirements.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is a fair and unbiased method of measuring airline safety?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-04-15T14:52:45.977" Title="What is a fair and unbiased method of measuring airline safety?" Tags="&lt;safety&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2014-04-15T23:34:24.097" ContentLicense="CC BY-SA 3.0" />
  <row Id="3387" PostTypeId="2" ParentId="3382" CreationDate="2014-04-15T11:11:34.473" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;So why aren't there any sort of &quot;minified&quot; winglets available as an aftermarket installation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Actually the DA42 has them&#xA;&lt;img src=&quot;https://i.stack.imgur.com/7fdSO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and in the MPP version they are even more pronounced&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WQzFA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-04-15T14:18:13.377" LastActivityDate="2014-04-15T14:18:13.377" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3388" PostTypeId="2" ParentId="3300" CreationDate="2014-04-15T12:28:48.103" Score="23" Body="&lt;p&gt;Quadcopters are not an efficient design -- one large rotor is far more efficient than four smaller rotors.  The reason quadcopters became popular is that they are mechanically simpler, safer (due to the smaller rotors) and far easier to control by software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, recent advances in machine learning have made so that helicopters can be controlled by software.  I'd expect to see a resurgence in helicopter-style drones because of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I'm not an aeronautics engineer but I suspect there's considerable merit in combining attributes from a quadcopter and a helicopter.  Imagine one large fixed-pitch rotor driven by an electric motor.   A few small additional electric-motor driven rotors could provide the needed pitch, yaw, and roll control.  Electricity would be generated by an efficient gas engine spinning at near constant speed.  Enough backup power to land could be provided by small batteries.  This design would be extremely reliable due to the greater reliability and simplicity of motors and fixed pitch rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Advancements will come, but slowly since the costs and dangers of human-carrying vehicles are so high.&lt;/p&gt;&#xA;" OwnerUserId="2121" LastActivityDate="2014-04-15T12:28:48.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3389" PostTypeId="2" ParentId="3378" CreationDate="2014-04-15T13:39:20.687" Score="31" Body="&lt;p&gt;I find that virtually all the passengers I've let fly for the first time were already so scared of the controls that no &quot;safety briefing&quot; of that sort was necessary.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Don't fight me on the controls.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If I say let go, let go immediately.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you suspect there's even a remote chance of either of these problems, maybe you shouldn't be letting this person fly your plane.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Don't move any of the controls very rapidly.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Don't move any of the controls to their limits.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In most small airplanes without hydraulics, it takes quite a bit of force to deflect any of the controls rapidly to their limits. And as soon as your first-time passenger starts to push on the controls, they're going to feel increasingly strong g-forces as the plane responds. For first-timers, this is usually a pretty intimidating feel. If someone is pushing too hard, they're going to feel it, and almost certainly back off or let go entirely.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&quot;Positive transfer of control&quot; using 3-step acknowledgment such as &lt;em&gt;&quot;You have the controls&quot; / &quot;I have the controls&quot; / &quot;You have the controls&quot;&lt;/em&gt; is a good idea for flight training, or for flights with 2 pilots taking turns at the controls; but in my opinion it's not necessary for a joyride with a friend. As the PIC, and the only licensed pilot in the cockpit, you need to be monitoring the situation at all times anyway. If you decide the situation requires you to reassert control, you can simply ask them to release the controls. If you can't trust the person to do this promptly, you probably shouldn't be letting them fly your plane anyway; a preflight safety briefing isn't going to solve that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To be as safe as possible, you can take the following steps before allowing your passenger to fly (some of these you already stated):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Select a location away from controlled airspace, busy airway/routes, or other special-use areas like drop zones.&lt;/li&gt;&#xA;&lt;li&gt;(Optionally, if you don't mind the extra radio chatter) Tune a nearby ATC radar facility (approach/center) and request radar advisories. Tell them you'll be maneuvering in a certain area.&lt;/li&gt;&#xA;&lt;li&gt;Climb to a sufficient altitude to allow good clearance from all terrain and obstacles (antennas, etc.), and to allow enough altitude for recovery if your passenger should somehow manage to stall or enter a steep dive or something.&lt;/li&gt;&#xA;&lt;li&gt;Trim for straight &amp;amp; level flight at $V_A$ &lt;em&gt;for your current weight&lt;/em&gt; (lower than the gross-weight $V_A$ you get out of the book).&lt;/li&gt;&#xA;&lt;li&gt;Make a set of clearing turns and scan for any traffic in the area.&lt;/li&gt;&#xA;&lt;li&gt;Give your systems a once-over and verify you have sufficient fuel.&lt;/li&gt;&#xA;&lt;li&gt;Hand over the controls!&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You didn't specifically ask about this, but I've flown with a &lt;em&gt;lot&lt;/em&gt; of first-time passengers, people who have never been in an airplane. Both children and adults. Many of them are understandably quite nervous. Here are some things I try to do to make it as easy, fun, relaxed and stress-free as possible for them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Give them a &lt;em&gt;simplified, plain English&lt;/em&gt; description of the flight. Tell them exactly what you plan to do and what order things will happen in. E.g.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First we're going to start the engine. I'll get on the radio and get clearance from the control tower. Then we'll taxi out to the runway and stop for a few minutes while I go through some checks to make sure the plane's in good shape. Then we'll take off and head out to the east to do some sightseeing. While we're up there, if you're comfortable and would like to try your hand at the controls, we can do that. When we're done with that we'll turn around and head back to the airport, land, and taxi back in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Don't&lt;/strong&gt; use fancy words or terms that a non-pilot wouldn't understand.&lt;/li&gt;&#xA;&lt;li&gt;Help them enter the airplane. Show them how to open and shut the door. Show them how to buckle and unbuckle their seat belt.&lt;/li&gt;&#xA;&lt;li&gt;Ask them if they have any questions.&lt;/li&gt;&#xA;&lt;li&gt;Do your normal preflight safety briefing, again using &lt;em&gt;simplified English&lt;/em&gt; and avoiding pilot terms. Limit it to points that are relevant to a passenger (avoiding the controls, staying quiet if asked, opening the door). They do NOT need to hear about what you're going to do if you have an engine failure on climbout. If this is a normal part of your preflight / before takeoff briefing (as it should be), say it to yourself mentally, not out loud.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;During the flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Talk your way through &lt;em&gt;everything you're doing&lt;/em&gt;. When you're ready to do your run-up, tell them:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm about to run the engine up to power to make sure everything's running smoothly. I'm holding the brakes so we're not going to go anywhere, but the engine will get pretty loud for a minute.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When you're doing your magneto / prop governor checks:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Now I'm going to do some things to the engine to make sure it's running right. It's going to make some pretty funny noises, but it's perfectly normal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Talking through everything accomplishes a few goals:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Avoids startling the passenger with something unexpected. A prop governor check sounds &lt;em&gt;really bad&lt;/em&gt; to somebody who knows about engines but nothing about planes. A stall horn in the flare may be perfectly normal to you but a loud buzzing alarm is the last thing the first-timer will be expecting to hear. Tell them about it ahead of time.&lt;/li&gt;&#xA;&lt;li&gt;Makes the passenger feel like they're a part of the flight and not just dead weight in the plane.&lt;/li&gt;&#xA;&lt;li&gt;Keeps &lt;em&gt;you&lt;/em&gt; focused on your tasks as PIC and discourages you from getting distracted in conversation with your passenger.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Make the flight &lt;em&gt;as smooth as possible&lt;/em&gt;. Don't overcontrol the airplane. If you drift 100' from your intended altitude, don't pull 2 g's to get back up to it. Make it slow and gentle. They're not a pilot, chances are they're not going to know you drifted 100 feet. They &lt;em&gt;will&lt;/em&gt; know if you jerk the thing around. &lt;strong&gt;DO NOT hot dog the airplane&lt;/strong&gt;. You may be bored with slow, gentle flight, but your passenger isn't.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Speak slowly, clearly and &lt;strong&gt;confidently&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Smile and try to look like you're having fun&lt;/strong&gt;. Your first-time passenger is probably feeling pretty vulnerable. When people are vulnerable they feed on the emotions of the people around them. If you look like you're having the time of your life, they're probably going to have fun too. If you look angry, ticked off or scared, you're going to scare them too even if the flight is perfectly smooth. &lt;strong&gt;This is especially true and critically important with children!&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If/when they're ready to take the controls:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Show them how the yoke controls pitch and roll. Do some (very) gentle climbs and rolls to illustrate what various control inputs do.&lt;/li&gt;&#xA;&lt;li&gt;Tell them to &lt;strong&gt;look outside&lt;/strong&gt; and not to worry about all the fancy intimidating lights and dials in the cockpit. Tell them that the only tool a pilot needs to fly the plane in good weather is their eyes.&lt;/li&gt;&#xA;&lt;li&gt;Tell them to &lt;strong&gt;relax and have fun&lt;/strong&gt;! Assure them that they aren't going to crash the plane or break anything and that you're there watching and won't let them do anything unsafe.&lt;/li&gt;&#xA;&lt;li&gt;After a few minutes, once they get the hang of basic control inputs, you can start to tell them about sight references: show them how to look at the horizon and tell if they're banked, climbing or descending. After 15-30 minutes you should be able to get virtually any passenger to be able to hold straight &amp;amp; level attitude and make gentle turns. Being able to accomplish this is &lt;em&gt;very rewarding&lt;/em&gt; for your passenger and makes them feel like they achieved something. It encourages their excitement about aviation and makes them want to fly again.&lt;/li&gt;&#xA;&lt;li&gt;Don't forget to do &lt;strong&gt;your&lt;/strong&gt; job: scan for traffic. Monitor your engine gauges. Listen for ATC calls. Don't stray into controlled airspace. &quot;Maintain situational awareness.&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've had a great deal of success using these tips when flying with first-timers and children. In 16 years of flying I have had only one bad experience, with an adult passenger who had an unknown (to me) and pretty severe anxiety problem and had a panic attack shortly after takeoff. A couple of kids have fallen asleep on me (which I took as a compliment). Everyone else had the time of their life. And let me tell you... if you're someone who loves flying, there is &lt;strong&gt;no better feeling&lt;/strong&gt; than sharing that with someone else and watching their excitement. It's the closest you'll ever come to reliving your own first flight, which hopefully you remember fondly because somebody cared as much as you do about being the best possible ambassador for aviation!&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-16T13:16:03.930" LastActivityDate="2014-04-16T13:16:03.930" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3390" PostTypeId="2" ParentId="2695" CreationDate="2014-04-15T14:11:34.890" Score="5" Body="&lt;p&gt;An interesting noise you can hear is the sound of the PTU (Power Transfer Unit) during the A320 startup. It sounds like a cross between a dog barking and someone dragging a wet finger across glass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=9aGsXmNjPRw&quot; rel=&quot;noreferrer&quot;&gt;https://www.youtube.com/watch?v=9aGsXmNjPRw&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens is that the PTU is transfering pressure from one hydraulics system to the other to equalize them. Since the pressure is not always unequal between the hydraulics systems, this is not audible during every startup.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastActivityDate="2014-04-15T14:11:34.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3391" PostTypeId="2" ParentId="3300" CreationDate="2014-04-15T14:32:21.997" Score="4" Body="&lt;p&gt;The reason quadcopters are chosen as platforms for small, computer controlled flying machines is because they are by design more agile and simpler to move in and around all three axes. This is because they are by design very very &lt;strong&gt;unstable&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is in fact impossible for a human to control a quadcopter (that can move in and around all three axes) without the aid of a computer or some other kind of artificial stabilizer. The reason computers can control quadcopters is because they are fast enough to produce control input that counters any small destabilizing forces that act on the frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to imagine the inherent stability of a flying platform is to consider what would happen if you would let go of the controls. Normal airplanes and helicopters will tend to just keep flying to the same direction. If you let go of the controls of a quadcopter (and have no stabilizing mechanism installed) the quadcopter will very quickly just chaotically tumble towards the ground. This means that in a helicopter or an airplane the design &quot;helps&quot; you and forces the frame to fly in a stable manner (forwards.) In a quadcopter there is no such help but there are also no forces that hinder you from moving towards any direction you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This principle is also deliberately on frames such as the F-117. The F-117 is impossible to fly without the help of computers (it was designed to be unstable), but this has made it a much more agile airplane than its frame would normally have allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other (bigger) reason quadcopters have not been scaled up is because they consume (a lot) more fuel than other types of aircraft. Why would anyone build a quadcopter when a helicopter or an airplane does the job using less fuel. They are also slow and noisy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the &quot;job&quot; for scaled up airframes is usually to move stuff from point A to point B while the &quot;job&quot; for small, computer controlled quadcopters is to be agile.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastActivityDate="2014-04-15T14:32:21.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3393" PostTypeId="2" ParentId="3355" CreationDate="2014-04-15T16:26:12.230" Score="4" Body="&lt;p&gt;All Wings courses that qualify for a Flight Review include both a online knowledge activites as well as required flight activities that are verified by a CFI. These flight requirements generally end up being longer than the 1 hr minimum flight time required by &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/EF04A9EEDC087ADF8625768F005C1BC3?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;§61.56&lt;/a&gt;.  But if you are completing a Wings course for the purpose of insurance discounts, a BRF would be a side benefit.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To accomplish each Phase of WINGS, you can attend safety seminars,&#xA;  take online courses, and demonstrate flight proficiency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, section 1.3 of the &lt;a href=&quot;https://www.faasafety.gov/documents/WINGS_Manual.pdf&quot; rel=&quot;nofollow&quot;&gt;Wing Manual&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note that pilots need not accomplish the flight review requirements of&#xA;  14 CFR part &#xA;  61.56, if he or she has satisfactorily completed any Phase in the WINGS - Pilot  Proficiency Program&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, the answer is yes, you can use Wings phases as a substitute for a flight review, but it might not be the most efficient way.&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="423" LastEditDate="2014-04-15T16:33:21.120" LastActivityDate="2014-04-15T16:33:21.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3394" PostTypeId="1" AcceptedAnswerId="3395" CreationDate="2014-04-15T17:19:41.703" Score="8" ViewCount="1080" Body="&lt;p&gt;I've been taught to always sump the plane's fuel system before going flying to check for water / contamination / proper fuel grade. However, I've yet to go flying in rain. What's the proper procedure to drain fuel during rain? If I took the fuel cap off to dump the fuel back into the plane, I'd be worried about rainwater getting in the tanks.&lt;/p&gt;&#xA;" OwnerUserId="2124" LastEditorUserId="97" LastEditDate="2014-10-29T01:20:11.300" LastActivityDate="2014-10-29T01:20:11.300" Title="How do you sump fuel when it's raining outside?" Tags="&lt;fuel&gt;&lt;aircraft-systems&gt;&lt;preflight&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3395" PostTypeId="2" ParentId="3394" CreationDate="2014-04-15T17:46:25.917" Score="1" Body="&lt;p&gt;AOPA has a good article about &lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/skills/checksamples.html&quot; rel=&quot;nofollow&quot;&gt;checking fuel&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... check the fuel caps and replace worn, brittle, or cracked seals&#xA;  that can allow rain to seep into the tanks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You cannot be 100% that the fuel does not contain any contamination. If you risk that by putting the sample fuel back in the airplane (debatable topic) will add more water in the tanks, then simply don't do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess since many flight schools offer wet rentals, they don't want to waste a drop of fuel. But it is okay to do that, so that their aircraft and your life are safer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many arguments about putting sump fuel back in the tank. Many people say that a GATS Jar is there to capture the contamination and then you can put it back in the fuel tank. In Cessna training material, they use a container where you can put sump fuel. At many places, there is a fine for throwing it on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in case of rain, the best option is to put in such a container. However, if it is raining that hard with strong gusty winds, I am sure taking care of sump fuel should not be your problem.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-04-16T13:52:04.683" LastActivityDate="2014-04-16T13:52:04.683" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3397" PostTypeId="1" AcceptedAnswerId="3398" CreationDate="2014-04-15T19:04:21.890" Score="16" ViewCount="7984" Body="&lt;p&gt;My initial thought is that night currency satisfies daytime currency, but what gives me pause is &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot;&gt;FAR 61.57(a)(2)&lt;/a&gt; notes that a non-current pilot is allowed to conduct day VFR or day IFR flights without passengers to obtain currency.  There is no mention of night flight being allowed.  This seems to imply that day flights are required for daytime currency.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="62" LastEditDate="2019-07-20T15:00:23.447" LastActivityDate="2019-07-20T15:00:23.447" Title="Does night takeoff and landing currency also count for daytime currency?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="3398" PostTypeId="2" ParentId="3397" CreationDate="2014-04-15T19:29:02.927" Score="13" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, night landings satisfy the requirements of §61.57(a)(1) for both nighttime and daytime currency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wording of the regulation is not crystal clear, and some (including me) have thought that the wording of (a)(2) required daytime landings for daytime currency. This is not the case, per the following interpretation from the FAA (Springfield, IL FSDO, dated 16 April 2014):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Please note, in this section, there is no mention of a day or night differences in the regulation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In 14 CFR 61.57(b) the regulation specifically mentions the requirement for Night Takeoffs and Landings and the time period they can be completed in.   If the passenger carrying will be done at night, the additional requirements of 14 CFR 61.57(b) must be met.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The night takeoffs and landings, as required by 14 CFR 61.57(b), will qualify for both the day and night requirement, provided all other requirements are met.   The day takeoffs and landings will NOT qualify for the night (section (b)) requirement though.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Stanley E. Swank II&lt;br&gt;&#xA;  Aviation Safety Inspector&lt;br&gt;&#xA;  Springfield, IL FSDO, AGL-19&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Other sources on the Internet agree with this interpretation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.askacfi.com/342/can-night-currency-count-towards-day-currency.htm&quot;&gt;Eric Gideon at askacfi.com&lt;/a&gt;:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... your three takeoffs and landings to a full stop at night will also fulfill the recent flight experience requirements for day currency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=27916&quot;&gt;A thread at pilotsofamerica.com&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-16T15:20:22.277" LastActivityDate="2014-04-16T15:20:22.277" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3399" PostTypeId="2" ParentId="3397" CreationDate="2014-04-15T19:37:17.223" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot; rel=&quot;nofollow&quot;&gt;FAR 61.57(a)(2)&lt;/a&gt; is for the purpose of fulfilling (a)(1). Meaning, if you are out of day currency than you must make day landings.  If are day current, then night landings will qualify to continue your day currency. &lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-04-15T19:37:17.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3400" PostTypeId="2" ParentId="3397" CreationDate="2014-04-15T19:38:06.290" Score="6" Body="&lt;h2&gt;Yes, night landings count for day currency.&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot; rel=&quot;noreferrer&quot;&gt;61.57(a)(1)&lt;/a&gt; explains:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Except as provided in paragraph (e) of this section, no person may act as a pilot in command of an aircraft carrying passengers or of an aircraft certificated for more than one pilot flight crewmember unless that person has made at least three takeoffs and three landings within the preceding 90 days.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Period.  That's it.&lt;/p&gt;&#xA;&lt;p&gt;Night currency limitations simply add an extra caveat to the above: you have to have done the landings to a full stop.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;But what about 61.57(a)(2)?  It clearly says day VFR or day IFR?&lt;/h2&gt;&#xA;&lt;p&gt;Your question is slightly misleading.  (a)(2) talks about how to regain currency after you've already lost it...and the quote in your question is incorrect.  You said this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;a non-current pilot is allowed to conduct day VFR or day IFR flights without &lt;strong&gt;passengers&lt;/strong&gt; to obtain currency&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;No!&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The reg actually says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;provided no persons or property are carried on board the aircraft, other than &lt;strong&gt;those necessary&lt;/strong&gt; for the conduct of the flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A non-current pilot is allowed to act as pilot in command in order to become current, so long as nobody is carried other than those individuals who are necessary for the conduct of the flight.  Such as the first officer, a flight instructor, or an examiner.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;So why is there the day limitation?&lt;/h2&gt;&#xA;&lt;p&gt;&lt;em&gt;Because there's no restriction on multi-crew operations at night.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;61.57(a)(1)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Except as provided in paragraph (e) of this section, no person may act as a pilot in command of an aircraft &lt;strong&gt;carrying passengers or of an aircraft certificated for more than one pilot flight crewmember&lt;/strong&gt; unless that person has made at least three takeoffs and three landings within the preceding 90 days,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;vs&lt;/p&gt;&#xA;&lt;p&gt;61.57(b)(1)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Except as provided in paragraph (e) of this section, no person may act as pilot in command of an aircraft &lt;strong&gt;carrying passengers&lt;/strong&gt; during the period beginning 1 hour after sunset and ending 1 hour before sunrise, unless within the preceding 90 days that person has made at least three takeoffs and three landings to a full stop during the period beginning 1 hour after sunset and ending 1 hour before sunrise, and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you need to get current in a multi-crew airplane, you can.  (a)(2) says so.  &lt;strong&gt;You don't need to get current in a multi-crew airplane at night, because there's no restriction on multi-crew operations at night.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-15T19:48:50.873" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3402" PostTypeId="1" CreationDate="2014-04-16T01:26:24.427" Score="2" ViewCount="197" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/3398/167&quot;&gt;An answer to another question on Aviation.SE asks about the historical development of FAR 61.57.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How has FAR 61.57 changed over the years?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-04-16T01:37:09.827" Title="How has FAR 61.57 changed since 1969?" Tags="&lt;far-61&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2014-04-16T12:53:20.653" ContentLicense="CC BY-SA 3.0" />
  <row Id="3403" PostTypeId="2" ParentId="3402" CreationDate="2014-04-16T01:27:15.410" Score="4" Body="&lt;h2&gt;Glad you asked!&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I referenced historical FARs from &lt;strong&gt;2013&lt;/strong&gt;, &lt;strong&gt;1993&lt;/strong&gt;, &lt;strong&gt;1988&lt;/strong&gt;, and &lt;strong&gt;1969&lt;/strong&gt;.  Here's what I found:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1wTqi.jpg&quot; alt=&quot;2013-1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sH1yB.jpg&quot; alt=&quot;2013-2&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/XgVc4.jpg&quot; alt=&quot;1993-1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lzi5f.jpg&quot; alt=&quot;1993-2&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/C8Egq.jpg&quot; alt=&quot;1988-1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/fNcfg.jpg&quot; alt=&quot;1988-2&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Pz02q.jpg&quot; alt=&quot;1969&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-04-16T01:27:15.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3404" PostTypeId="2" ParentId="3402" CreationDate="2014-04-16T01:37:09.827" Score="3" Body="&lt;p&gt;Why yes, it has, and the history along with the preambles and lots of other good information is available on the FAA's Regulatory Guidance Library.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Click the image and then click on Historical CFR and then By Part and follow the tree to 61.57 to see the history:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameset&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uoamv.png&quot; alt=&quot;RGL History&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More details are available here:  &lt;a href=&quot;https://aviation.stackexchange.com/questions/427/how-can-i-see-the-revision-history-of-a-particular-far&quot;&gt;How can I see the revision history of a particular FAR?&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-04-16T01:37:09.827" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3405" PostTypeId="1" CreationDate="2014-04-16T01:58:03.273" Score="14" ViewCount="1651" Body="&lt;p&gt;I want to build some software applications applied to the aviation industry and would want to know if any U.S. / FAA regulation could apply in the design of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are some regulations when a software holds information related with finance, health or kids.&lt;/p&gt;&#xA;" OwnerUserId="2130" LastEditorUserId="97" LastEditDate="2014-04-16T02:17:47.607" LastActivityDate="2014-04-17T05:00:04.543" Title="Is there any U.S. / FAA regulation that could apply for aviation software?" Tags="&lt;faa-regulations&gt;&lt;software&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3406" PostTypeId="1" CreationDate="2014-04-16T02:21:50.557" Score="2" ViewCount="1266" Body="&lt;p&gt;A great question's been asked: &lt;a href=&quot;https://aviation.stackexchange.com/questions/3405/is-there-any-u-s-faa-regulation-that-could-apply-for-aviation-software&quot;&gt;Is there any U.S. / FAA regulation that could apply for aviation software?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is interesting to me as a programmer and aviation enthusiast, but being based in the UK,  I'd like to know if there any &lt;em&gt;EASA&lt;/em&gt; regulations surrounding the creation of software for use in the aviation industry?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2020-08-09T08:16:34.517" Title="Are there any EU/EASA regulations surrounding aviation software?" Tags="&lt;easa-regulations&gt;&lt;software&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3407" PostTypeId="5" CreationDate="2014-04-16T02:44:08.027" Score="0" Body="&lt;p&gt;The &lt;strong&gt;Dash 8&lt;/strong&gt; (officially the &lt;strong&gt;DHC-8&lt;/strong&gt;) is a series of regional &lt;a href=&quot;/questions/tagged/airliner&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airliner&amp;#39;&quot; rel=&quot;tag&quot;&gt;airliner&lt;/a&gt;s originally built by&#xA;de Havilland Canada. They are powered by two Pratt &amp;amp; Whitney PW100-series&#xA;&lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt; engines. From 1992 to 2019, the aircraft were built by&#xA;&lt;a href=&quot;/questions/tagged/bombardier&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bombardier&amp;#39;&quot; rel=&quot;tag&quot;&gt;bombardier&lt;/a&gt;, and, since then, the newly formed company De Havilland&#xA;Aircraft Co. of Canada has taken over production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Four variants have been built:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;strong&gt;Series 100&lt;/strong&gt; was the first variant (entering service in 1984), and has a &lt;a href=&quot;/questions/tagged/passenger&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;passenger&amp;#39;&quot; rel=&quot;tag&quot;&gt;passenger&lt;/a&gt; capacity of 37 to 40 seats; unlike the later variants, no Q-version was ever offered for the Series 100.  Production of the Series 100 ended in 2005 after building 299 aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;Series 200&lt;/strong&gt;, introduced in 1995, has the same length and capacity as the Series 100, but the more powerful &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt;s of the Series 300 (albeit running at a slightly lower &lt;a href=&quot;/questions/tagged/thrust&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust&lt;/a&gt; rating) - which it postdates, despite its lower version number - resulting in improved &lt;a href=&quot;/questions/tagged/aircraft-performance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-performance&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-performance&lt;/a&gt;.  105 Series 200s were built before production ended in 2009.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;Series 300&lt;/strong&gt; was introduced in 1989, with a stretched cabin (along with more powerful engines to power the bigger, heavier aircraft) which increased its capacity to 50 to 56 seats.  The last Series 300, #267, was delivered in 2009.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;Series 400&lt;/strong&gt; was introduced in 1999, with an even-further-stretched cabin (making it more than twice as long as the Series 100 and 200), a larger &lt;a href=&quot;/questions/tagged/tail&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail&lt;/a&gt;, &lt;em&gt;much&lt;/em&gt;-more-powerful engines, and a capacity of 68 to 90 seats.  587 Series 400s have been delivered as of March 2019; the Series 400 is the only Dash 8 version still in production, with 58 unfilled orders.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since mid-1996, an active &lt;a href=&quot;/questions/tagged/noise-reduction&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;noise-reduction&amp;#39;&quot; rel=&quot;tag&quot;&gt;noise-reduction&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/vibration&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vibration&amp;#39;&quot; rel=&quot;tag&quot;&gt;vibration&lt;/a&gt;-cancelling system has been installed; these newer, quieter aircraft (including the later Series 200s and 300s, and all Series 400s) are known as the Q-Series (Q200, Q300, and Q400). A total of 1258 aircraft have been delivered as of March 2019.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_Dash_8&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="33692" LastEditorUserId="22726" LastEditDate="2019-11-30T07:23:24.377" LastActivityDate="2019-11-30T07:23:24.377" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3408" PostTypeId="4" CreationDate="2014-04-16T02:44:08.027" Score="0" Body="Use for questions regarding specifics of any aircraft in the de Havilland Canada / Bombardier Dash 8 series (also known as the DHC-8 or Q-series)." OwnerUserId="72" LastEditorUserId="22726" LastEditDate="2019-11-30T00:03:15.320" LastActivityDate="2019-11-30T00:03:15.320" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3409" PostTypeId="2" ParentId="3406" CreationDate="2014-04-16T02:54:01.653" Score="2" Body="&lt;p&gt;Two relevant standards from &lt;a href=&quot;https://www.eurocae.net&quot; rel=&quot;nofollow&quot;&gt;EUROCAE (European Organisation for Civil Aviation Equipment)&lt;/a&gt; are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ED-109A / Guidelines for CNS/ATM Systems Software Integrity Assurance&lt;/li&gt;&#xA;&lt;li&gt;ED-153 / Guidelines for ANS Software Safety Assurance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Unfortunately these documents are not freely available. However, you can find some information about the contents of these documents from other sites, such as &lt;a href=&quot;http://www.ldra.com/index.php/en/solutions/by-standard-adherence/do-278&quot; rel=&quot;nofollow&quot;&gt;LDRA&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-04-16T02:54:01.653" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3410" PostTypeId="2" ParentId="3405" CreationDate="2014-04-16T04:14:28.660" Score="1" Body="&lt;p&gt;As a general statement, a number of software vendors making non-certified applications are sure to include big bold warnings that the software is only used to increase situational awareness and should not be relied upon for instrument conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the &lt;a href=&quot;http://static.garmincdn.com/pumac/190-01501-00_0K_Web.pdf&quot; rel=&quot;nofollow&quot;&gt;Garmin Pilot Manual&lt;/a&gt; has a number of disclaimers (most common sense) to remind you that it is not a substitute for other systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, as Qantas 94 Heavy pointed out, the answer is quite different for certified avionics, and that depends on which part of the FAR the aircraft is being certified under.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you make something like an E6B app, you're probably in the clear.  After all, you would have just made some calculator with preprogrammed functions.&lt;/p&gt;&#xA;" OwnerUserId="2074" LastActivityDate="2014-04-16T04:14:28.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3411" PostTypeId="2" ParentId="3406" CreationDate="2014-04-16T06:29:51.027" Score="4" Body="&lt;p&gt;If we speak about &lt;strong&gt;airborne&lt;/strong&gt; software, the main document is the RTCA/EUROCAE &lt;a href=&quot;http://en.wikipedia.org/wiki/DO-178C&quot; rel=&quot;nofollow&quot;&gt;DO-178/ED-12&lt;/a&gt; currently at the &quot;C&quot; version: &lt;code&gt;Software Considerations in Airborne Systems and Equipment Certification&lt;/code&gt;: if you want to certify (and thus commercialize) your software for flight, this is the main document to read.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the scope of the software and the design/development process there might be different supplements (see &lt;a href=&quot;http://en.wikipedia.org/wiki/DO-178C#Differences_with_DO-178B&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;DO-330 &lt;code&gt;Software Tool Qualification Considerations&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-331 &lt;code&gt;Model-Based Development and Verification Supplement to DO-178C and DO-278&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-332 &lt;code&gt;Object-Oriented Technology and Related Techniques Supplement to DO-178C and DO-278A&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-333 &lt;code&gt;Formal Methods Supplement to DO-178C and DO-278A&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It has been prepared by the RTCA/EUROCAE joint committee and approved by both FAA and EASA under different names, but the content is the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @Greg mentions, these documents are &lt;a href=&quot;http://www.rtca.org/store_list.asp&quot; rel=&quot;nofollow&quot;&gt;not freely&lt;/a&gt; available&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="19" LastEditDate="2015-01-04T10:49:29.470" LastActivityDate="2015-01-04T10:49:29.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3412" PostTypeId="2" ParentId="3405" CreationDate="2014-04-16T08:11:10.423" Score="12" Body="&lt;p&gt;For &lt;strong&gt;simulators&lt;/strong&gt; you have &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.1.1&amp;amp;rgn=div5&quot; rel=&quot;noreferrer&quot;&gt;Part 60 of CFR 14&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;strong&gt;airborne&lt;/strong&gt; software the FAA has published &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1021710&quot; rel=&quot;noreferrer&quot;&gt;AC 20-115&lt;/a&gt;, but the main document that refers to is the FAA/EASA &lt;a href=&quot;http://en.wikipedia.org/wiki/DO-178C&quot; rel=&quot;noreferrer&quot;&gt;RTCA DO-178/ED-12&lt;/a&gt; currently at the &quot;C&quot; version: &lt;code&gt;Software Considerations in Airborne Systems and Equipment Certification&lt;/code&gt;.&lt;br&gt;&#xA;If you want to certify (and thus commercialize) your software for flight, this is the main document to read.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the scope of the software and the design/development process there might be different supplements (see &lt;a href=&quot;http://en.wikipedia.org/wiki/DO-178C#Differences_with_DO-178B&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;DO-330 &lt;code&gt;Software Tool Qualification Considerations&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-331 &lt;code&gt;Model-Based Development and Verification Supplement to DO-178C and DO-278&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-332 &lt;code&gt;Object-Oriented Technology and Related Techniques Supplement to DO-178C and DO-278A&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;li&gt;DO-333 &lt;code&gt;Formal Methods Supplement to DO-178C and DO-278A&lt;/code&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It has been prepared by the RTCA/EUROCAE joint committee and approved by both FAA and EASA under different names, but the content is the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that these documents are &lt;a href=&quot;http://www.rtca.org/store_list.asp&quot; rel=&quot;noreferrer&quot;&gt;not freely available&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="64" LastEditDate="2014-04-17T05:00:04.543" LastActivityDate="2014-04-17T05:00:04.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3413" PostTypeId="1" AcceptedAnswerId="3415" CreationDate="2014-04-16T13:29:42.570" Score="20" ViewCount="41522" Body="&lt;p&gt;I mean, on the one hand it seems kind of obvious, if you had a fuel tank that was mostly water then you would lack combustible materials for the engine, but I get the impression that having any water in the fuel tank at all is considered a really bad idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is that?  Is it all right to have a very small amount of water in the fuel tanks?  Is there a defined percentage of liquid in the fuel tank that must be fuel in order to operate safely? (say 99.87% or something?)  And does this differ from prop to turboprop to turbofan to jet?&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2018-02-25T18:37:28.463" Title="Why is water in the fuel tank bad?" Tags="&lt;safety&gt;&lt;fuel&gt;&lt;engine&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3414" PostTypeId="2" ParentId="3413" CreationDate="2014-04-16T13:41:19.070" Score="4" Body="&lt;p&gt;Since water is more dense then kerosine, the water will sink to the bottom, where the fuel tank outlet also happens to be, meaning that if there is a sizeable amount, the engine will stop, since there's simply nothing to burn.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Approximate densities of a few fuels:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Water: 1 kg/l&lt;/li&gt;&#xA;&lt;li&gt;Kerosine: 0.82 kg/l&lt;/li&gt;&#xA;&lt;li&gt;100LL: 0.72 kg/l&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-16T13:41:19.070" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3415" PostTypeId="2" ParentId="3413" CreationDate="2014-04-16T13:42:36.480" Score="20" Body="&lt;p&gt;Fuel systems are in general fed by gravity, at least until the fuel leaves the tank, where sometimes (always if the tank is lower than the engine) a pump pushes it toward the engine. This means that fuel is generally extracted from the bottom of the tank (or slightly above the very bottom to avoid having small particles from the bottom of the tank clogging up the fuel filter, incidentally this also introduces the concept of &lt;code&gt;unusable fuel&lt;/code&gt;, as the stuff remaining at the bottom of the tank, although there are a lot more factors to this).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel is less dense than water, meaning it'll float on top of the water. Or if you want to think of it the other way around, water is heavier and will sink to the bottom, right where you're trying to get your fuel to feed to the engine. Water doesn't burn very well and the engine will stop. Avgas is generally 0.72 kg/l and Jetfuel around 0.82 kg/l (water being 1 kg/l, see have &lt;a href=&quot;http://en.wikipedia.org/wiki/International_System_of_Units&quot; rel=&quot;noreferrer&quot;&gt;SI&lt;/a&gt; units work well that way?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tiny amount of water probably mix with the fuel and simply reduce the power output slightly, whereas anything more will be drained from the tank first, and it'll be very hard to restart the engine. You'd have to pump all the water through the cylinder and out the exhaust, and I don't think this is generally possible in flight, especially right after takeoff which is generally the case when you have water in the fuel (could be right after switching tanks too though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know much about turbine engines, but I suspect they're less susceptible as the water will not prevent relighting the engine (the pumps will simply push the water out, there's no cylinder that could fill up with water), and you'll generally be using up more fuel on the ground making the problem readily apparent. This is pure speculation though.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-09-14T12:59:31.300" LastActivityDate="2014-09-14T12:59:31.300" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3416" PostTypeId="1" AcceptedAnswerId="3417" CreationDate="2014-04-16T16:10:04.267" Score="17" ViewCount="3997" Body="&lt;p&gt;I have read that some airplanes have multiple autopilots, specifically airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this, and how does that system work?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-04-16T23:12:30.760" Title="What is the purpose of multiple autopilots?" Tags="&lt;autopilot&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3417" PostTypeId="2" ParentId="3416" CreationDate="2014-04-16T16:32:09.647" Score="21" Body="&lt;p&gt;&lt;strong&gt;Redundancy&lt;/strong&gt;, particularly during &lt;a href=&quot;http://en.wikipedia.org/wiki/Autoland&quot; rel=&quot;noreferrer&quot;&gt;autoland&lt;/a&gt; operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;How it works&lt;/em&gt; depends on the specific airplane type. In the most advanced systems with triple (or more) flight guidance computers (FGCs), a &quot;voting&quot; concept is used during critical operations like autoland. All 3 computers calculate their commands independently, and vote on what to do. The middle value, or sometimes the average of the 2 &quot;most similar&quot; values, is then passed to the flight control actuators. In this way, if any one of the computers fails and starts producing garbage commands, those erroneous commands will not be selected (they are automatically rejected by the voting scheme). A monitoring system can also detect a failed computer in this way and take it offline, allowing &quot;fail-active&quot; functionality — an autoland can continue on the 2 remaining functional computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less complex aircraft, and aircraft without autoland, still sometimes have 2 FGCs, but do not support fail-active operation. In these systems only one of the two computers is active or selected at any given time. A transfer switch in the cockpit allows the pilot to transfer control from one computer to the other if one fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it's not just airliners. Business jets commonly also have dual FGCs, and in recent times even small general aviation airplanes like the Diamond DA-42 have dual systems (Garmin G1000 in dual-GFC700 configurations).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iMSGf.jpg&quot; alt=&quot;CJ Plus&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iMSGf.jpg&quot; rel=&quot;noreferrer&quot;&gt;This photo&lt;/a&gt; (click for high res version) shows a Cessna Citation CJ business jet with dual Garmin autopilots. At the top of the PFD, notice there is a small green arrow pointing left; this indicates the left FGC is currently selected. The photo also shows the XFR (transfer) button on the mode select panel, top center, just underneath the master caution/warning annunciator panel. Pushing this button would switch to the right (#2) FGC and change the arrow on the PFD to point to the right. These indications are fairly representative of other dual-FGC systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Df4kq.jpg&quot; rel=&quot;noreferrer&quot;&gt;Here's another photo&lt;/a&gt; of a Hawker 800 with Rockwell Collins Pro Line 21. You can see the same arrow on the PFDs. In this aircraft the transfer switch is labeled &quot;AP XFR&quot; and is again on the autopilot panel just underneath the glareshield at the top of the panel toward the left hand side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And finally &lt;a href=&quot;https://i.stack.imgur.com/zqhbh.jpg&quot; rel=&quot;noreferrer&quot;&gt;a photo of a 767&lt;/a&gt; with 3 FGCs and full autoland capability. It's a bit hard to read in this photo, but just above the autopilot disengage bar (the &quot;spacebar&quot; looking thing on the right side of the mode select panel just under the glareshield) the 3 buttons are labeled &quot;A/P ENGAGE&quot;, &quot;L&quot; &quot;C&quot; and &quot;R&quot; for the left, center and right FGCs. During an autoland all 3 would be selected and illuminated.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="97" LastEditDate="2014-04-16T23:12:30.760" LastActivityDate="2014-04-16T23:12:30.760" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3418" PostTypeId="2" ParentId="3413" CreationDate="2014-04-16T16:33:16.427" Score="13" Body="&lt;p&gt;Water in the fuel system is something of an over-inflated issue in aviation. Most aircraft have unusable sections of the fuel tank that will hold upwards of one gallon. That means that unless you have a gallon of water in the tanks it's unlikely that you'll be picking any up. We sump the tanks before every flight because it's easy to prevent an issue, and we're also pulling out any debris which is a much bigger issue than water. But if you're just running along and a bit of water sloshes into the fuel intake, it's unlikely that you'll even notice. Now obviously an engine can't burn straight water, and that's why we have systems in place to mitigate how much gets into the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small amounts of water injected into the engine will actually boost performance. Water's heat-absorption properties allow it to (once injected) suck up much of the left-over heat from the engine's previous combustion cycle. This means that the engine is cooled and less work needs to be done to compress the fuel/air mixture. Upon combustion, the water vaporizes and expands much better than dry air, boosting compression greatly. The practice of using water (and often alcohol) in engines is known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Water_injection_%28engine%29&quot;&gt;Water Injection&lt;/a&gt; and has been around for a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, putting too much water in the engine can over-boost compression, which can result in blown cylinders, cracked pistons, and many other forms of damage. It can also lead to hydro-lock, which is when the expanded water vapor occupies more volume than the cylinder provides. This can at best stall the engine, or at worse blow a cylinder.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-16T16:33:16.427" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3420" PostTypeId="2" ParentId="2065" CreationDate="2014-04-16T19:36:19.667" Score="1" Body="&lt;p&gt;The missed approach procedure is published with considering the terrain in the area. It is calculated that an aircraft can safely go around clearing the terrain if it starts go-around at the DH. If the aircraft descents below DH, and decides to go around things go different. Because now it starts the procedure approximately 200' below and also 1NM ahead of the published missed approach procedure. This is a balked landing, and has to be handled with more care. to carry out the engine out SID after balked landing in low visibility conditions also has to be considered&lt;/p&gt;&#xA;" OwnerUserId="2138" LastActivityDate="2014-04-16T19:36:19.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3421" PostTypeId="1" CreationDate="2014-04-16T19:47:41.933" Score="9" ViewCount="2128" Body="&lt;p&gt;Please note, this question does not call into question whether or not the conspiracy theory is true or untrue, but the feasibility of certain chemicals being used as fuel additives in order to make the theory viable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chemtrail conspiracy theorists believe that there are certain additives being put into jet fuel to spew out [nano-]particles that rain down on us, for means that are being kept secret.  The hypothesized reasons behind 'chemtrailing' range anywhere from weather modification, population reduction, and sunlight blocking to reduce the earths temperature hence combatting global warming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some popular agents that are called into speculation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aluminium based aerosols &lt;/li&gt;&#xA;&lt;li&gt;Mono-atomic gold &lt;/li&gt;&#xA;&lt;li&gt;Barium &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My question is, wouldn't these additives, chemicals, etc, cause adverse reactions inside the jet engines, if the turbine is the actual catalyst supposedly spraying these things?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastEditorUserId="167" LastEditDate="2015-02-18T06:23:03.973" LastActivityDate="2019-01-16T17:14:28.513" Title="If jet engines did leave chemtrails, wouldn't the chemicals cause adverse reactions in the engines?" Tags="&lt;turbine&gt;&lt;contrails&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3422" PostTypeId="2" ParentId="3421" CreationDate="2014-04-16T20:10:50.080" Score="12" Body="&lt;p&gt;Jet fuel is seldom if ever pure hydrocarbon molecules. It's got a lot of other stuff mixed into it to improve the properties. I'm going to quote Shell for the sake of examples:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Antioxidants (gum inhibitors) must be used in Avgas to prevent the&#xA;  formation of gum and other antioxidation products. Jet fuels, which&#xA;  are inherently more stable than gasolines, may contain them, depending&#xA;  on the treatment process used during manufacture.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A metal deactivator - now rarely used - may be added to nullify the&#xA;  effects of dissolved trace metals, especially copper, which can impair&#xA;  the thermal stability of jet fuels.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Corrosion inhibitors can be used to reduce corrosion in fuel system&#xA;  and improve the lubricity - lubricating properties - of jet fuels.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fuel system icing inhibitors reduce the freezing point of any water&#xA;  that may be in the fuel system and prevent the formation of ice&#xA;  crystals that could restrict fuel flow. They are mandatory in military&#xA;  Jet but are not used in civil aircraft that have fuel heaters. They&#xA;  may be added to either Jet or Avgas during the fuelling of small&#xA;  aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Static dissipater additives minimise the hazardous effects of static&#xA;  charges that build up during movement of jet fuels. They are sometimes&#xA;  used in Avgas as well. &lt;a href=&quot;http://www.shell.com/global/products-services/solutions-for-businesses/aviation/shell-aviation-fuels/fuels/aeroshell-performance-additive101.html&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Further analysis&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No practical application:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aluminium based aerosols, Mono-atomic gold, Nano aluminum-coated fiberglass, Radioactive thorium, Cadmium, Chromium, Nickel, Desiccated blood, Mold spores, Yellow fungal mycotoxins, Polymer fibers, Barium.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Useful additives from your list:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Ethylene dibromide- Anti-Knock agent in aviation fuel.&lt;/li&gt;&#xA;  &lt;li&gt;Alumium: &lt;a href=&quot;http://en.wikipedia.org/wiki/Aluminium_borohydride&quot;&gt;Derivatives&lt;/a&gt; containing it have been used.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many of the materials you list might have the very real potential to (seriously) damage jet turbines and piston engines if mixed in during extended use.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-04-16T20:16:54.970" LastActivityDate="2014-04-16T20:16:54.970" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3423" PostTypeId="1" AcceptedAnswerId="3424" CreationDate="2014-04-16T21:59:30.080" Score="19" ViewCount="7209" Body="&lt;p&gt;At the club I fly at, there is an older Cessna 172 that has a manual &quot;Johnson Bar&quot; that is used to put the flaps down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the newer 152, and I believe the rest of the planes (I have yet to fly them), the flaps are controlled via a electronic (or hydraulic?) lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to me that the manual flaps are more reliable, more maintainable, and a hell of a lot more fun in my opinion. Additionally, the manually flaps don't require a lot of strength to operate IMO. Does anyone know why the automatic design is favored over the manual counterpart? Same question applies to car transmissions...&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="62" LastEditDate="2014-12-08T14:33:44.557" LastActivityDate="2019-02-08T22:41:11.707" Title="Why did Cessna get rid of manual flaps in their 172?" Tags="&lt;flaps&gt;&lt;cessna-172&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3424" PostTypeId="2" ParentId="3423" CreationDate="2014-04-16T22:54:26.697" Score="22" Body="&lt;p&gt;Nobody can definitively answer this for you except Cessna's 1965/1966 engineering team (the year they made the change), but there are two reasons I can think of:&lt;br&gt;&#xA;&lt;strong&gt;Because switches are cooler than Johnson bars&lt;/strong&gt;; or &lt;strong&gt;Because &lt;em&gt;everyone else&lt;/em&gt; is doing electric flaps&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much like with manual transmissions, some people just don't like the extra work of manual flaps, and for those folks electric &quot;flip a switch and don't worry about it&quot; flaps are a selling point. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In terms of reliability it's a trade-off (as are all engineering decisions), so let's look at a few of the factors:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mechanical Flaps&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Flaps still work when the battery is dead.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;The pilot can control the extension/retraction rate to some extent.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Usually cross-linked with a bar (so you can't have a &quot;split-flap&quot; condition)&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Simple to rig, adjust, and maintain.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;-&lt;/code&gt;Actuation requires more pilot skill&lt;br&gt;&#xA;You need to develop the muscle memory to grab the handle without looking.&lt;br&gt;&#xA;You need to learn to govern the extension/retraction rate smoothly.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;-&lt;/code&gt;The failure mode is usually &quot;Flaps Up&quot;&lt;br&gt;&#xA;You could lose your flaps on short final if the cable or lock mechanism fails.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Electric Flaps&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;&quot;Easier to Operate&quot; (you don't need to reach down to the floor)&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Extension/Retraction rate is constant (governed by the motor)&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Fewer moving cables running through the fuselage (wires replace them)&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Typical failure mode (e.g. dead battery) is &quot;Flaps stuck where you left them&quot;&lt;br&gt;&#xA;Less chance of losing your flaps on short final.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;+&lt;/code&gt;Depending on the design they may save some weight over a mechanical system.&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;-&lt;/code&gt;You lose control of the flaps if the battery dies (no-flap landings are more likely)&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;-&lt;/code&gt;You have one or more motors to maintain/replace if they fail&lt;/li&gt;&#xA;&lt;li&gt;&lt;code&gt;-&lt;/code&gt;Depending on the design it's possible to have a &quot;split-flap&quot; condition&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cessna's engineers and marketing folks looked at those factors (and probably many others) and decided that electric flaps &quot;made sense&quot;. On the other side of the GA fleet, Piper's engineers looked at the same factors and decided to keep the Johnson bar flaps (which are still found in the PA-28 series today).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a manufacturing standpoint it makes sense for all of the aircraft a manufacturer produces to use the samecontrol mechanisms -- either &lt;em&gt;all the planes use mechanical flaps&lt;/em&gt; or &lt;em&gt;all the planes use electric flaps&lt;/em&gt; because it simplifies production and allows everything to run through on one assembly line rather than stopping at the flaps and diverting aircraft to different teams.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-16T22:54:26.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3425" PostTypeId="1" AcceptedAnswerId="3426" CreationDate="2014-04-17T02:26:28.727" Score="14" ViewCount="6081" Body="&lt;p&gt;I always wondered if it was possible for planes and other aircraft to leave the Earth's atmosphere. Normal commercial transport airplanes can fly pretty high, but then they need air to get the speed boost from. Reactive engines seem like a better idea, but I don't know how much importance air has for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to get to space from Earth's surface using a non-rocket aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1542" LastEditorUserId="1467" LastEditDate="2014-04-18T16:23:20.573" LastActivityDate="2019-03-27T11:30:57.197" Title="Can aircraft other than rockets go to space?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;aircraft-limitations&gt;" AnswerCount="7" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3426" PostTypeId="2" ParentId="3425" CreationDate="2014-04-17T06:21:52.677" Score="26" Body="&lt;p&gt;Depends on what you mean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Get to high altitude? Yes you can. It is really inefficient to get there, but some aircraft already do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Achieve a stable orbit and be able to maintain control? No, at those altitudes you do not have enough oxygen to keep your engines running, you have to bring your own (and thus use a rocket)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the sake of clarity, some definitions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;reaction engine&lt;/strong&gt;: includes both rockets and jets. The engine pushes some mass in one direction and by &lt;em&gt;reaction&lt;/em&gt; it achieves thrust in the opposite one.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;jet&lt;/strong&gt; (engine): is used to refer to &lt;em&gt;airbreathing&lt;/em&gt; engines. The aircraft carries the fuel, but not the oxidizer; that is taken from the surrounding atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;rocket&lt;/strong&gt; (engine): is used to refer to &lt;em&gt;non-airbreathing&lt;/em&gt; engines. The (space)craft carries both the fuel and the oxidizer. No atmosphere is needed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;space&lt;/strong&gt;: above 100km of altitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://what-if.xkcd.com/58/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;go to space&lt;/strong&gt;&lt;/a&gt;: &#xA;&lt;img src=&quot;https://i.stack.imgur.com/onDp5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;staying in space&lt;/strong&gt;:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/YG8nz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Images from &lt;a href=&quot;http://what-if.xkcd.com/58/&quot; rel=&quot;nofollow noreferrer&quot;&gt;xkcd&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="5517" LastEditDate="2019-03-27T11:30:57.197" LastActivityDate="2019-03-27T11:30:57.197" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="3427" PostTypeId="2" ParentId="3425" CreationDate="2014-04-17T09:15:54.383" Score="9" Body="&lt;p&gt;For certain values of &quot;go to space&quot;, yes.  The &lt;a href=&quot;https://en.wikipedia.org/wiki/Karman_line&quot;&gt;Karman line&lt;/a&gt; (the altitude at which an airplane cannot generate enough lift to stay aloft at any speed slower than orbital velocity) is usually considered the lower edge of outer space.  This implies that with a powerful engine and enough fuel it's possible to &quot;fly&quot; up into space: you just keep gaining altitude and speed until you find yourself in orbit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No aircraft has actually done this.  The &lt;a href=&quot;https://en.wikipedia.org/wiki/X-15&quot;&gt;X-15&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Scaled_Composites_SpaceShipOne&quot;&gt;SpaceShipOne&lt;/a&gt; were both able to reach that altitude in zoom climbs; neither went fast enough to stay there.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-04-17T09:15:54.383" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3428" PostTypeId="1" AcceptedAnswerId="3467" CreationDate="2014-04-17T09:51:10.077" Score="20" ViewCount="16810" Body="&lt;p&gt;Most wings suffer from induced drag due to a pressure difference above and below the wing causing air to sneak around the tip, forming a vortex. There are various methods to minimize these effects, such as winglets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, looking at the &lt;a href=&quot;http://www.synergyaircraft.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Synergy aircraft&lt;/a&gt; as an example, box wings have no wing tips. Disregarding any other parts of the aircraft, are the wings actually free from induced drag? Or are they still causing induced drag, just in a way I'm not able to think of with my limited fluid dynamics experience?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7xlK8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7xlK8.jpg&quot; alt=&quot;Synergy aircraft with box wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Synergy aircraft with box wings (picture &lt;a href=&quot;http://synergyaircraft.com/wp-content/uploads/2014/05/Synergy_wide.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read somewhere that a traditional bi-plane design is less efficient due to the wings interfering with each other (apparently something addressed by the synergy aircraft by placing the upper wing further back or something), and the upper wing is actually more of a tail-plane, pushing down, thus further increasing the airspeed in between the airfoils if I understand correctly and eliminating the pressure differential from the top of the upper wing to the bottom of the lower wing, and both wings would of course generate normal drag by cutting through the air, but I'm only interested in the induced drag at this point.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="1961" LastEditDate="2018-07-21T20:38:08.210" LastActivityDate="2019-11-20T20:06:50.230" Title="Do box-wings suffer from induced drag the same way as normal wings?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="3429" PostTypeId="2" ParentId="3428" CreationDate="2014-04-17T10:04:46.530" Score="10" Body="&lt;p&gt;They're not &lt;em&gt;free&lt;/em&gt; from induced drag, but the induced drag is greatly diminished, as demonstrated in Prandtl's &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1924/naca-tn-182.pdf&quot; rel=&quot;noreferrer&quot;&gt;NACA paper from 1924&lt;/a&gt; and reported in &lt;a href=&quot;http://books.google.de/books?id=wiVsjBsySX8C&amp;amp;pg=PA182&amp;amp;lpg=PA182&amp;amp;dq=prandtl%20paper%201924%20induced%20drag%20naca&amp;amp;source=bl&amp;amp;ots=kf_9INzYbJ&amp;amp;sig=v7_6cPvV8zijyXlVh2oqwy7riTI&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=56VPU5KvK6ar7AbY24CABQ&amp;amp;redir_esc=y#v=onepage&amp;amp;q=prandtl%20paper%201924%20induced%20drag%20naca&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;this book&lt;/a&gt; (See chapter 11)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RGcub.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The authors of that book applied the results to the design of &lt;a href=&quot;http://www.idintos.eu/eng/&quot; rel=&quot;noreferrer&quot;&gt;this aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9rk75.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-04-17T10:04:46.530" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3430" PostTypeId="1" AcceptedAnswerId="3431" CreationDate="2014-04-17T13:37:32.547" Score="5" ViewCount="2492" Body="&lt;p&gt;As my question states, why is only a single Bluefin-21 being deployed underwater to scan the seabed with an area of around 40 square miles?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why aren't multiple Bluefin-21's getting deployed when deploying multiple machines would make the search faster when everything here is a very time consuming process?&lt;/p&gt;&#xA;" OwnerUserId="1466" LastEditorUserId="1466" LastEditDate="2014-04-17T17:55:08.593" LastActivityDate="2014-04-17T20:31:28.393" Title="Why is only a single underwater robotic submarine Bluefin-21 being deployed in the search for MH370?" Tags="&lt;search-and-rescue&gt;&lt;mh370-incident&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ClosedDate="2015-12-22T22:29:02.817" ContentLicense="CC BY-SA 3.0" />
  <row Id="3431" PostTypeId="2" ParentId="3430" CreationDate="2014-04-17T14:37:37.193" Score="13" Body="&lt;h2&gt;Bluefin-21&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why not multiple Bluefin-21's&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is only one Bluefin-21.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other Bluefins 12S, 12D, 9M etc are mostly for shallow water work.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Other AUVs&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Bluefin-21 is not the only commercial Autonomous Underwater Vehicle (AUV) equipped with side-scan sonar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Navy has spent $20M on an order for eight &lt;a href=&quot;http://en.wikipedia.org/wiki/Knifefish_%28robot%29&quot;&gt;Knifefish&lt;/a&gt; (a Bluefin-21 derivative) but these are not due to enter active service until 2017. They are for mine-detection and so (I surmise) may not be well suited to deep-ocean usage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Royal Navy has a number of REMUS 600 AUVs but these are not designed for use deeper than 600M&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be that most existing AUVs equipped with side-scan-sonar are not capable of deep-ocean use.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-04-17T15:40:54.600" LastActivityDate="2014-04-17T15:40:54.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3432" PostTypeId="1" AcceptedAnswerId="3434" CreationDate="2014-04-17T14:37:47.320" Score="8" ViewCount="834" Body="&lt;p&gt;I've been told that the best kinds of planes to train in are very small ones, like Cessna &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_150&quot;&gt;150s&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_152&quot;&gt;152s&lt;/a&gt;.  But I've never been clear as to why.  I know they are cheaper to operate, so is operation cost the only thing?  Or are there aerodynamic properties that 152s have that make them &quot;easier&quot;?  What makes for a good training aircraft?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="39" LastEditDate="2014-04-17T15:40:24.740" LastActivityDate="2018-11-12T22:28:28.247" Title="What are the properties of a good general aviation training aircraft?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;flight-training&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3433" PostTypeId="2" ParentId="2354" CreationDate="2014-04-17T14:42:32.737" Score="2" Body="&lt;p&gt;As stated before,  White is cheaper.  There is no thermal benefit for subsonic planes at cruising altitudes.  Windchill and ambient temperature at flight levels are below freezing. &lt;/p&gt;&#xA;" OwnerUserId="2144" LastActivityDate="2014-04-17T14:42:32.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3434" PostTypeId="2" ParentId="3432" CreationDate="2014-04-17T14:54:22.910" Score="11" Body="&lt;p&gt;Cost is certainly a primary factor in choosing smaller planes. It makes training much more accessible to people with less money to spend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small planes are also easier to fly for various reasons. They fly slower and respond more quickly than large aircraft, which gives the pilot much more margin for learning. Being more maneuverable can help them escape tricky situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These planes are also generally designed to be resistant to and recoverable from common aerodynamic disasters like stalls and spins. See this &lt;a href=&quot;https://aviation.stackexchange.com/questions/3484/how-is-a-wing-designed-to-be-stall-or-spin-proof&quot;&gt;related question&lt;/a&gt; for more information. There are FAA requirements for single-engine planes in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/78909ED5A6DBEB9485256687006D0568?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 23.221&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller planes generally also have fewer and less complex systems, which makes the necessary training easier to complete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can also operate from smaller airports, which gives a student more choices of where to do their training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there are always exceptions to these qualities, and large planes can have similar ones, but they hold true in general.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-04-18T18:23:40.897" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3436" PostTypeId="2" ParentId="3425" CreationDate="2014-04-17T18:43:39.080" Score="1" Body="&lt;p&gt;I'm not sure how you'd classify the proposed &lt;a href=&quot;http://en.wikipedia.org/wiki/Skylon_%28spacecraft%29&quot; rel=&quot;nofollow&quot;&gt;Skylon spacecraft&lt;/a&gt; spacecraft. It would be an airbreathing reactive engine in lower altitudes but a rocket above 26 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It might be a game changer. But this time I don't give even odds that Skylon will come to pass.&lt;/p&gt;&#xA;" OwnerUserId="2099" LastActivityDate="2014-04-17T18:43:39.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3437" PostTypeId="2" ParentId="3430" CreationDate="2014-04-17T20:31:28.393" Score="1" Body="&lt;p&gt;Most of capable AUVs belong to offshore drilling companies like Chevron and Royal Dutch Shell. Some are also operated by deep sea cable companies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The various armed forces operate only a handful of these AUVs, and because they are quite expensive, not many marine science institutes have them. &lt;/p&gt;&#xA;" OwnerUserId="2147" LastActivityDate="2014-04-17T20:31:28.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3438" PostTypeId="2" ParentId="3428" CreationDate="2014-04-17T21:49:17.980" Score="3" Body="&lt;p&gt;The main reason for induced drag is, that the wing accelerates the air above and below it downwards increasing it's kinetic energy and due to law of conservation of energy, it has to take that energy somewhere and the only way is by doing negative work on the aircraft, i.e. inducing drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of air accelerated per unit of time is proportional to the wing span and speed of the aircraft. Applying the same force to more air accelerates it to lower speed and because kinetic energy is proportional to square of speed it induces less drag. That's why high aspect ration (long span) wings are more efficient and why induced drag decreases with speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.av8n.com/how/img48/trailing.png&quot; alt=&quot;wingtip vortices&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wingtip vortices are simply borders of this area of descending air. And because you can't generate lift without accelerating air downward (by law of action and reaction), this induced drag is principal and any finite-span wing will induce it . And it will only depend on the lift generated, wingspan and speed and &lt;em&gt;nothing&lt;/em&gt; else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices&quot; rel=&quot;nofollow noreferrer&quot;&gt;How It Flies, section 3.13&lt;/a&gt; (the figure is from there).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now there is some additional induced drag caused by higher-pressure air flowing around the wing-tip which does not contribute to lift (or even slightly negatively), but contributes to drag. It is maybe low tens of percent or something like that. The several percent that can be saved by various measures are significant enough to be worth the effort, but they are still several percent. Miracles are not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, the box wing still has tips. Air can't flow to or from between the wings, but it can flow from under the lower horizontal surface to above the upper one. Plus the wing is relatively low aspect ratio.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.037" LastActivityDate="2014-04-17T22:37:37.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3439" PostTypeId="1" CreationDate="2014-04-17T22:24:52.713" Score="7" ViewCount="4519" Body="&lt;p&gt;I was watching some police programme on TV the other day, with an air chase that had the police helicopter crew on their toes; having to perform a lot of sudden maneuvers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do police, or HEMS (medical), helicopters communicate with ATC? I presume they get priority, but do ATC clear other traffic out of the way? Is there a comms person/navigator on-board? Do they simply &quot;see and avoid&quot;?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="3504" LastEditDate="2015-01-01T22:06:26.010" LastActivityDate="2015-01-01T22:06:26.010" Title="How do police/ambulance helicopters communicate with ATC?" Tags="&lt;air-traffic-control&gt;&lt;helicopter&gt;&lt;uk&gt;&lt;crew&gt;&lt;emergency-services&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3440" PostTypeId="5" CreationDate="2014-04-17T22:26:19.553" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-17T22:26:19.553" LastActivityDate="2014-04-17T22:26:19.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3441" PostTypeId="4" CreationDate="2014-04-17T22:26:19.553" Score="0" Body="For use on questions about police/ambulance/fire aircraft and ground vehicles." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-17T22:51:27.813" LastActivityDate="2014-04-17T22:51:27.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3442" PostTypeId="1" CreationDate="2014-04-17T22:34:37.723" Score="15" ViewCount="1239" Body="&lt;p&gt;Take Afghanistan as a for instance; do governments (e.g. USAF/RAF) or NATO construct ATC towers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd imagine so, at the air bases, in order to land/takeoff the vast amount of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who controls the sectors where missions are ongoing? How are the different countries' aircraft coordinated and kept apart?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-17T22:39:47.470" LastActivityDate="2014-04-17T22:56:51.807" Title="Are ATC towers built in warzones?" Tags="&lt;air-traffic-control&gt;&lt;military&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3443" PostTypeId="2" ParentId="3439" CreationDate="2014-04-17T22:36:09.540" Score="9" Body="&lt;p&gt;The exact procedures will vary locally but typically ATC will give priority to police and ambulance helicopters that operate emergency services. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If these helicopters are operating in controlled airspace, communication with ATC will be done by normal VHF radio. There is no need for a dedicated communications person, the pilot will be in contact with ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sudden manoeuvring of these flights is rarely a problem for ATC since these aircraft are operating under Visual Flight Rules. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When chasing a car, the pilot remains responsible for keeping clear of obstacles and other traffic, therefore this requires a second person to keep a look out (either on the car or the surroundings)&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-17T22:36:09.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3444" PostTypeId="5" CreationDate="2014-04-17T22:45:24.237" Score="0" Body="&lt;p&gt;The Netherlands is a country in north-western Europe. It is a member of the International Civil Aviation Organisation (ICAO).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Airlines&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The major airline of the Netherlands is &lt;a href=&quot;http://www.klm.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;KLM&lt;/a&gt;, part of Air France - KLM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airlines are: Transavia, Martinair (Cargo), both are part of KLM&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Airports&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The major airport is Schiphol, located close to the capital Amsterdam. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Amsterdam Airport Schiphol&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Schiphol is a large international airport that serves over 300 destinations worldwide. It serves 58 million passengers per year (2015), of which about 40% is using the airport for transfer, and 1.6 million metric tonne of cargo. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ICAO: EHAM&lt;/li&gt;&#xA;&lt;li&gt;IATA: AMS&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;Runways:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;04 / 22   2015 m&lt;/li&gt;&#xA;&lt;li&gt;06 / 24   3500 m&lt;/li&gt;&#xA;&lt;li&gt;09 / 27   3450 m &lt;/li&gt;&#xA;&lt;li&gt;18L/36R 3400 m&lt;/li&gt;&#xA;&lt;li&gt;18C/36C 3300 m&lt;/li&gt;&#xA;&lt;li&gt;18R/36L   3800 m&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Rotterdam / The Hague Airport&lt;/h3&gt;&#xA;&#xA;Runways:&#xA;&#xA;&lt;h3&gt;Maastricht / Aachen Airport&lt;/h3&gt;&#xA;&#xA;Runways:&#xA;&#xA;&lt;h3&gt;Groningen / Eelde Airport&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Groningen airport Eelde is primarily used for training flights. It is the home of the KLM flight academy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the summer season a limited number of holiday flights to about 10 destinations are performed from this airport.&lt;/p&gt;&#xA;&#xA;Runways:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;01/19 1 500 m × 45 m &lt;/li&gt;&#xA;&lt;li&gt;05/23  2 500 m × 45 m&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Eindhoven Airport&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Eindhoven Airport is a Civil/Military airport &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Nation Aviation Authorities&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Dutch Civil Aviation Authority (CAA-NL) is part of The Human Environment and Transport Inspectorate (Inspectie Leefomgeving en Transport). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the Netherlands are a member of the EU, much of the aviation legislation is coming from EU law. The European Aviation Safety Agency (EASA) is responsible for part of the supervision on aviation in the Netherlands.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Air Traffic Control&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are three parties providing Air Traffic Control in the Netherlands; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Luchtverkeersleiding Nederland (LVNL)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;EUROCONTROL Maastricht Upper Area Control (MUAC)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Royal Netherlands Air Force (Dutch Mil)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Air Traffic Control in the Netherlands is done by Luchtverkeersleiding Nederland (LVNL). They provide approach and tower control at Amsterdam, Rotterdam, Maastricht and Groningen airport as well as en-route control below FL245&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EUROCONTROL Maastricht Upper Area Control provides en-route control above Flight Level 245&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Links&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ais-netherlands.nl/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Services (AIS) Netherlands&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8282" LastEditorUserId="8282" LastEditDate="2018-10-22T21:11:13.353" LastActivityDate="2018-10-22T21:11:13.353" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3445" PostTypeId="4" CreationDate="2014-04-17T22:45:24.237" Score="0" Body="Use this tag for questions specifically relating to aviation in the Netherlands." OwnerUserId="97" LastEditorUserId="19" LastEditDate="2016-07-19T14:12:21.163" LastActivityDate="2016-07-19T14:12:21.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3446" PostTypeId="5" CreationDate="2014-04-17T22:46:57.853" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/European_Union&quot; rel=&quot;nofollow&quot;&gt;The European Union&lt;/a&gt; (EU) is a political and economic union of European member states. Use this tag for questions about aviation within the EU, but remember that the EU does not include all European countries, and several countries are members of EASA but not the EU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your question is about aviation regulations in Europe, then the &lt;a href=&quot;/questions/tagged/easa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;easa&amp;#39;&quot; rel=&quot;tag&quot;&gt;easa&lt;/a&gt; tag is the correct one to use.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="62" LastEditDate="2015-05-26T13:45:02.857" LastActivityDate="2015-05-26T13:45:02.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3447" PostTypeId="4" CreationDate="2014-04-17T22:46:57.853" Score="0" Body="The European Union (EU) is a political and economic union of European member states. Use this tag for questions about aviation within the EU, but remember that the EU does not include all European countries, and several countries are members of EASA but not the EU.&#xD;&#xA;&#xD;&#xA;For questions about the European Union specifically; use the [easa] tag instead if appropriate." OwnerUserId="97" LastEditorUserId="8282" LastEditDate="2020-03-02T12:26:43.817" LastActivityDate="2020-03-02T12:26:43.817" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3448" PostTypeId="2" ParentId="3442" CreationDate="2014-04-17T22:56:51.807" Score="16" Body="&lt;p&gt;Yes, sometimes control towers or other ATC facilities are constructed to support air traffic control. If, for example an ATC tower is needed (there was none previously or it was destroyed), a mobile replacement is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fpz3k.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NAMS2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For mission control Airborne Warning and Control Systems (AWACS) are used:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XKml0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But these are quite expensive to fly. If possible, mobile surface based radars are brought in to provide a surveillance picture. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mobile towers, radars and navigation beacon are not solely used in war situations. In natural disasters they have proven to be useful as well: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avstop.com/news_jan_2010/faa_sends_temporary_air_traffic_control_tower_to_haiti.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA sends temporary Air Traffic Control tower to Haiti&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fl9nf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-17T22:56:51.807" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3449" PostTypeId="2" ParentId="2175" CreationDate="2014-04-17T23:09:41.120" Score="5" Body="&lt;p&gt;Theoretically the diameter of the rotor plus some room for the tail is sufficient. If it fits, it fits. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practically, a bit of room for manoeuvring is required. Also special attention to the generated turbulence is needed in cramped spaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regulatory I don't know the exact size required for the EC135 operated as air ambulance in the Netherlands. But I do know that the Dutch police helicopters are allowed to land on an area with a diameter of 1.5 $\times$ LOA (length over all) during daytime operations. They hit a lamp mast once which resulted in &lt;a href=&quot;http://onderzoeksraad.nl/uploads/items-docs/521/2008021_PH-RPZ.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this investigation&lt;/a&gt; (in Dutch - or &lt;a href=&quot;http://translate.google.com/translate?sl=auto&amp;amp;tl=en&amp;amp;js=y&amp;amp;prev=_t&amp;amp;hl=en&amp;amp;ie=UTF-8&amp;amp;u=http://onderzoeksraad.nl/uploads/items-docs/521/2008021_PH-RPZ.pdf&amp;amp;edit-text=&quot; rel=&quot;nofollow noreferrer&quot;&gt;English text-only translation&lt;/a&gt;) by the Onderzoeksraad (Dutch Safety Board). Page 5 and 6 show some of the regulations in force at the time (2008).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ag8XM.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="97" LastEditDate="2014-04-17T23:13:35.217" LastActivityDate="2014-04-17T23:13:35.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3450" PostTypeId="1" CreationDate="2014-04-17T23:44:55.227" Score="9" ViewCount="2471" Body="&lt;p&gt;I recall that during US1549's birdstrike incident that resulted in it &lt;a href=&quot;https://aviation.stackexchange.com/questions/2685/how-exactly-did-us1549-land-on-the-hudson&quot;&gt;landing on the Hudson&lt;/a&gt;, a large amount of migrating geese weighing upto 20lbs each were sucked into the A320's engines &amp;mdash; far bigger and heavier than previously certified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that at the time the engines were tested &amp;amp; certified by throwing small chickens or similar, one at a time, into the engines. Has this certification process been improved at all since this incident?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-10-31T14:28:43.430" Title="How are jet engines certified against birdstrikes?" Tags="&lt;safety&gt;&lt;aircraft-certification&gt;&lt;multi-engine&gt;&lt;birds&gt;&lt;us1549-accident&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3451" PostTypeId="2" ParentId="3450" CreationDate="2014-04-18T00:11:32.550" Score="8" Body="&lt;p&gt;There are hundreds of tests that need to be performed for certification of a turbine engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requirements and tests are listed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.16#14:1.0.1.3.16.5&quot;&gt;CFR part 33 E and F&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Amongst them are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum static thrust tests&lt;/li&gt;&#xA;&lt;li&gt;Vibration tests&lt;/li&gt;&#xA;&lt;li&gt;Endurance tests&lt;/li&gt;&#xA;&lt;li&gt;Water ingestion test&lt;/li&gt;&#xA;&lt;li&gt;Hail ingestion test&lt;/li&gt;&#xA;&lt;li&gt;Ice cloud test&lt;/li&gt;&#xA;&lt;li&gt;Bird strike test&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A number of them can be seen in &lt;a href=&quot;https://www.youtube.com/watch?v=jTKfFxwpbUU&quot;&gt;this video&lt;/a&gt; of the GE90-115 Engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific requirement for bird ingestion are described in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.16#14:1.0.1.3.16.5.363.16&quot;&gt;&amp;sect;33.76&lt;/a&gt;. The number of birds to be used and their weight depends on the area of the engine inlet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been several changes to the bird ingestion requirements for certification since the A320 engine was certified in 1996. However, once an engine is certified there is no need to demonstrate compliance to the updated requirements; the engine remains certified as it was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The latest update to these requirements was in 2007, prior to the Hudson accident. To answer your question: no, there have not been any changes to the bird strike testing requirements of engines in the aftermath of the Hudson accident. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-04-18T15:14:33.170" LastActivityDate="2014-04-18T15:14:33.170" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3452" PostTypeId="5" CreationDate="2014-04-18T00:30:04.260" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.ntsb.gov/doclib/reports/2010/AAR1003.pdf&quot; rel=&quot;nofollow&quot;&gt;Official NTSB report (PDF)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:41:26.440" LastActivityDate="2015-04-02T01:41:26.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3453" PostTypeId="4" CreationDate="2014-04-18T00:30:04.260" Score="0" Body="The January 15, 2009 accident involving the ditching of US Airways flight 1549 on the Hudson River about 8.5 miles from LaGuardia Airport, New York City, after an almost complete loss of thrust in both engines following an encounter with a flock of birds." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-18T02:09:23.760" LastActivityDate="2014-04-18T02:09:23.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3454" PostTypeId="1" AcceptedAnswerId="3460" CreationDate="2014-04-18T00:47:19.943" Score="4" ViewCount="1194" Body="&lt;p&gt;Reading the NTSB's &lt;a href=&quot;https://www.ntsb.gov/doclib/reports/2010/AAR1003.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;accident report&lt;/a&gt; on US1549, there is a transcript of the CVR from page 149 onwards in the PDF (marked as page 130 on hardcopy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small clips of the ATC/crew communications exist, but I'm curious to know whether the NTSB also release the full audio recording, per the transcript provided? It's much longer than other clips I can find online.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/3057/can-i-get-official-recordings-of-atc-audio&quot;&gt;Can I get official recordings of ATC audio?&lt;/a&gt; (asks for FAA, not NTSB).&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-31T14:26:05.537" Title="Does the NTSB provide CVR audio recordings alongside transcripts in accident reports?" Tags="&lt;air-traffic-control&gt;&lt;cockpit-voice-recorder&gt;&lt;ntsb&gt;&lt;us1549-accident&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3455" PostTypeId="1" AcceptedAnswerId="82930" CreationDate="2014-04-18T01:08:14.290" Score="13" ViewCount="9775" Body="&lt;p&gt;On the sidesticks of Airbus aircraft, there is a Priority Takeover button. &lt;a href=&quot;http://en.wikipedia.org/wiki/Side-stick&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; has this to say:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In typical Airbus side-stick implementations, the sticks are independent. The plane's computer either aggregates multiple inputs or a pilot can press a &amp;quot;priority button&amp;quot; to lock out inputs from the other side-stick.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;On US flight 1549, &lt;a href=&quot;https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf&quot; rel=&quot;noreferrer&quot;&gt;the CVR transcript&lt;/a&gt; shows that Sully hit the Priority T/O button, after the co-pilot (Skiles) handed over control of the aircraft:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;15:27:23.2&lt;/em&gt; - &lt;strong&gt;Sully:&lt;/strong&gt; My aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;15:27:24.0&lt;/em&gt; - &lt;strong&gt;Skiles:&lt;/strong&gt; Your aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;15:27:26.5&lt;/em&gt; - &lt;strong&gt;FWC:&lt;/strong&gt; Priority left.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I'm curious as to why there's a need for this button at all?&lt;/p&gt;&#xA;&lt;p&gt;Here's a short video on YouTube, demonstrating this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/SKNJ-ABAPuY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-12-16T22:07:37.983" Title="Why is the Priority Takeover button used?" Tags="&lt;airbus&gt;&lt;sidestick&gt;&lt;fwc&gt;&lt;us1549-accident&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3456" PostTypeId="5" CreationDate="2014-04-18T01:10:30.400" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-18T01:10:30.400" LastActivityDate="2014-04-18T01:10:30.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3457" PostTypeId="4" CreationDate="2014-04-18T01:10:30.400" Score="0" Body="The Flight Warning Computer provides audible and visual warnings in the event of an on-board fault." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-18T02:09:13.543" LastActivityDate="2014-04-18T02:09:13.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3458" PostTypeId="1" CreationDate="2014-04-18T01:27:58.370" Score="8" ViewCount="4614" Body="&lt;p&gt;Watching a video entitled Airbus A330 Takeoff Sidestick View, there appears to be a lot of side-to-side movement of the sidestick, as well as a lot of pushing the nose down:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/8YaQch_y9DA?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was under the impression that movements on the control column should be smooth and not erratic &amp;mdash; what is the reason for the side-to-side movement? As far as I can see on the MFDs, there is no heading change prior to 02:50 (which appears to be done by the A/P anyway). Is it turbulence?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what is the reason for pushing the nose down? Is the plane naturally trying to pull up at too high of an angle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This landing video appears to show even more erratic control. Is this normal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Y4uHmvFbe7A?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:24:12.087" LastActivityDate="2015-10-01T19:24:12.087" Title="Why is there so much movement of the sidestick during this takeoff?" Tags="&lt;takeoff&gt;&lt;airbus&gt;&lt;pilot-technique&gt;&lt;sidestick&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3459" PostTypeId="1" AcceptedAnswerId="3491" CreationDate="2014-04-18T01:39:02.567" Score="9" ViewCount="4226" Body="&lt;p&gt;Watching a video on YouTube of an A340-600 takeoff, I noticed that it has at least two exterior cameras &amp;mdash; one for lining up the nosewheel, and the other on the tailfin:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/klZPGhxTk-s?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the NTSB &lt;a href=&quot;https://aviation.stackexchange.com/questions/96/can-i-attach-a-camera-to-the-outside-of-my-aircraft&quot;&gt;recommended the use of exterior cameras&lt;/a&gt; in 2012, I'm wondering how widespread these are? Which models of Airbus aircraft have them? Do any Boeings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do these record or are they realtime-only?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-01T19:12:57.387" Title="Which aircraft feature stock exterior cameras?" Tags="&lt;boeing&gt;&lt;airbus&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3460" PostTypeId="2" ParentId="3454" CreationDate="2014-04-18T01:50:44.637" Score="12" Body="&lt;p&gt;No. Federal law prohibits the NTSB from releasing any CVR recordings, and the NTSB notes that they are &lt;a href=&quot;https://www.ntsb.gov/foia/foia_exemptions.html&quot;&gt;exempt from FOIA requests.&lt;/a&gt; The same law requires them to release a transcript, like the ones seen in accident reports, if the transcript is relevant to the accident or incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.law.cornell.edu/uscode/text/49/1114&quot;&gt;49 U.S.C. § 1114(c)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) The Board may not disclose publicly any part of a cockpit voice or video recorder recording or transcript of oral communications by and between flight crew members and ground stations related to an accident or incident investigated by the Board. However, the Board shall make public any part of a transcript or any written depiction of visual information the Board decides is relevant to the accident or incident—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(A) if the Board holds a public hearing on the accident or incident, at the time of the hearing; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(B) if the Board does not hold a public hearing, at the time a majority of the other factual reports on the accident or incident are placed in the public docket.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="136" LastActivityDate="2014-04-18T01:50:44.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3461" PostTypeId="1" CreationDate="2014-04-18T01:51:38.167" Score="2" ViewCount="543" Body="&lt;p&gt;Referring to the automated callouts and sounds made by the &lt;a href=&quot;/questions/tagged/fwc&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fwc&amp;#39;&quot; rel=&quot;tag&quot;&gt;fwc&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/tcas&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tcas&amp;#39;&quot; rel=&quot;tag&quot;&gt;tcas&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/gpws&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gpws&amp;#39;&quot; rel=&quot;tag&quot;&gt;gpws&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/pws&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;pws&amp;#39;&quot; rel=&quot;tag&quot;&gt;pws&lt;/a&gt;, etc. &amp;mdash; are these available to download in one repository at all? For any aircraft, Airbus or Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Understandably, these may not be &lt;em&gt;freely&lt;/em&gt; available, but I'm curious otherwise too (e.g. the likes of Air Crash Investigation must do this).&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-05-14T03:20:57.903" Title="Are aircraft sounds publicly available in a repository?" Tags="&lt;boeing&gt;&lt;airbus&gt;&lt;website&gt;&lt;noise&gt;&lt;fwc&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3462" PostTypeId="1" AcceptedAnswerId="3472" CreationDate="2014-04-18T02:40:43.143" Score="10" ViewCount="4919" Body="&lt;p&gt;I've previously looked online for pilots jobs at airlines, from budget airlines to cargo carriers; and they always want you to have a &lt;a href=&quot;/questions/tagged/ppl&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ppl&amp;#39;&quot; rel=&quot;tag&quot;&gt;ppl&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any airlines currently run programmes for applicants with no prior flying experience?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-18T04:53:54.557" LastActivityDate="2016-09-27T03:52:08.577" Title="Do any airlines hire &quot;pilots&quot; with no previous flying experience?" Tags="&lt;commercial-aviation&gt;&lt;career&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3463" PostTypeId="2" ParentId="3462" CreationDate="2014-04-18T02:40:43.143" Score="11" Body="&lt;p&gt;British Airways ran the &lt;a href=&quot;https://jobs.ba.com/jobs/futurepilot/&quot; rel=&quot;noreferrer&quot;&gt;Future Pilots Programme&lt;/a&gt; in 2013, which offered applicants with only A-Levels (no university degree/diploma) aged 18-55, the chance to co-pilot an A320 or 737.&lt;/p&gt;&#xA;&lt;p&gt;Financially, this is how it worked:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;We have joined forces with Airline Placement Limited (APL), a subsidiary of CTC Aviation, and together we've designed a unique sponsorship scheme that will make flying feasible for all. APL will sponsor your flight training, jet orientation course and type rating.&lt;/p&gt;&#xA;&lt;p&gt;Obviously this represents a significant investment by APL and you will therefore be required to deposit a security bond of £84,000 with them. Because this is a sponsored scheme, this entire £84,000 security bond will be repaid to you, tax-free, if you successfully complete all training, and join British Airways as a first officer. The security bond is repaid in equal monthly instalments over your first seven years of employment, all in addition to your remuneration package.&lt;/p&gt;&#xA;&lt;p&gt;There are a number of ways you can raise the funds to deposit this security bond, for example from your own finances, borrowing from family, or securing a loan. If you're not in a position to secure an asset-based loan then you could be eligible for our British Airways guaranteed loan scheme. If this is the case, our partner bank will run a thorough check of your credit history.&lt;/p&gt;&#xA;&lt;p&gt;Should this come back clear and you pass the Future Pilot Programme selection process, British Airways could act as your loan guarantor. You will then be able to borrow the money from our partner bank in order to deposit the required security bond with APL. On any loan there is obviously a percentage of interest charged by the lender, but the British Airways guaranteed loan scheme specifically offers a 24-month holiday period before any loan repayments commence.&lt;/p&gt;&#xA;&lt;p&gt;The year 1 basic salary for a Future Pilot Programme first officer is £23,220, with a further £8-£10,000 of flying allowances typically being earned in a full year of flying.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In terms of the licence that you get:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Each training course in the Future Pilot Programme leads to the issuing of a Commercial Pilot's Licence (Aircraft) with Multi-Engine Instrument Rating. Theoretical knowledge (ground school) is examined to Air Transport Pilot Licence standard and so your licence will be issued with 'Frozen ATPL theory credit'. This combination is colloquially known as a 'Frozen ATPL'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Unfortunately, the programme is currently closed. That said, one source&lt;sup&gt;1&lt;/sup&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;All the 2014 slots have been filled and the opening for 2015 slots will probably occur in October or November. You will probably be competing with over 3,000 other applicants for 60 positions, so the odds of success are not high.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sub&gt;&lt;sup&gt;1&lt;/sup&gt; Ok, the source is &lt;a href=&quot;https://uk.answers.yahoo.com/question/index?qid=20140117030121AAeQ8aN&quot; rel=&quot;noreferrer&quot;&gt;Yahoo Answers!&lt;/a&gt; That said, the answerer is a top contributor in aviation.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-09-27T03:52:08.577" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3464" PostTypeId="1" CreationDate="2014-04-18T02:51:37.420" Score="9" ViewCount="8285" Body="&lt;p&gt;Is it possible to become a pilot in the UK with a criminal record?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="64" LastEditDate="2014-04-18T20:55:54.500" LastActivityDate="2014-10-23T09:37:01.513" Title="Can you be a commercial pilot if you have a criminal record?" Tags="&lt;commercial-aviation&gt;&lt;career&gt;&lt;uk&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3465" PostTypeId="2" ParentId="3464" CreationDate="2014-04-18T02:51:37.420" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www.britishairways.com/careers/futurepilot/fppFaqs.shtml&quot;&gt;British Airways&lt;/a&gt; has this to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you have been cautioned, warned or convicted of a criminal offence (other than parking offences) we suggest you check whether you will be able to obtain an airside pass by visiting &lt;a href=&quot;http://www.dft.gov.uk&quot;&gt;www.dft.gov.uk&lt;/a&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In order to be employed as a pilot with British Airways you will be required to undergo a Criminal Record Check for every country in which you have been a resident, or worked in, for 6 months or more in the past 3 years.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Admittedly, &lt;a href=&quot;http://www.dft.gov.uk&quot;&gt;the DFT&lt;/a&gt;'s website is a maze of information, and it seems very difficult to find any information; I'd suggest giving them a call, to find out for your particular convictions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airsidemanager.co.uk/Airside-Referencing.aspx&quot;&gt;Airside Manager&lt;/a&gt; has some more detailed information on airside passes, in general.&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-04-18T02:51:37.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3466" PostTypeId="1" AcceptedAnswerId="3470" CreationDate="2014-04-18T02:55:51.567" Score="5" ViewCount="4159" Body="&lt;p&gt;With the correct keywords on Google, it is possible to find Boeing MPDs (Maintenance Planning Documents), as well as Task Cards, and other technical documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering, could a software vendor with the need to access these documents legally obtain them?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2015-12-08T11:17:25.740" Title="Can you legally obtain Boeing maintenance documents?" Tags="&lt;aircraft-maintenance&gt;&lt;boeing&gt;&lt;boeing-737&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3467" PostTypeId="2" ParentId="3428" CreationDate="2014-04-18T04:04:21.200" Score="20" Body="&lt;p&gt;The box wing is only better when you compare wings with identical span. The two wings of a box wing work in different &lt;a href=&quot;https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-100-aerodynamics-fall-2005/lecture-notes/16100lectre19_cg.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Treffz planes&lt;/a&gt;, so the downwash is spread out vertically. The difference in induced drag to a single wing is not big, just a few percent. The friction drag is higher (see below), as is the structural mass, so the box wing needs to create more lift. This makes the induced drag of a box wing effectively higher than that of a single wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529#7529&quot;&gt;induced drag&lt;/a&gt;, anyway? It is the consequence of creating lift over a limited span. The wing creates lift by deflecting air downwards. This happens gradually over the wing's chord, and creates a reaction force orthogonally to the local speed of air. This means the reaction force is pointing up- and slightly backwards. This backwards component is induced drag! Wingtips are not involved and are not causing induced drag. Lift creation is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly fast, there is a lot of air mass streaming past the wing per unit of time, so you need to deflect the air only slightly. Your induced drag is small. Sames goes for a large span: There is more air which can be deflected, so the induced drag is small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A box wing needs two slim wings per side, which will have a smaller chord than a single wing of the same surface area. So their Reynolds number is smaller, and their friction drag is higher. Also, the wing spar is less thick and will need to be heavier to carry the same lift!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you drop the restriction of keeping span identical, the optimum single wing can afford to have more span (due to its better structural efficiency), and away goes the advantage of the box wing. And once you look at the full picture and add structural mass, the box wing never had this advantage in the first place.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Yes, but what about the Synergy?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Synergy is a clever design with some advantages, but it cannot cheat physics. These are the advantanges:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pusher prop keeps the airframe free of wake turbulence, so more area can be kept in laminar flow.&lt;/li&gt;&#xA;&lt;li&gt;The pusher prop sucks the air from the rear fuselage, effectively avoiding separation.&lt;/li&gt;&#xA;&lt;li&gt;The two stubby tailbooms and fins give great protection for the propeller area on the ground.&lt;/li&gt;&#xA;&lt;li&gt;The compact layout keeps the stabilizing effect of the propeller small, so maneuverability does not suffer much.&lt;/li&gt;&#xA;&lt;li&gt;The use of composites and glider airframe technologies reduce friction drag.&lt;/li&gt;&#xA;&lt;li&gt;The diesel engine consumes cheaper jet fuel and is more fuel-efficient than a gasoline engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that I did not mention the box wing design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing sweep in a propeller aircraft looks cool, but increases drag, because the wing must be bigger to create the same lift.&lt;/li&gt;&#xA;&lt;li&gt;In total, this configuration has four vertical tails, each of them with its own interference drag and a short chord which, again, increases drag over a comparable single vertical tail.&lt;/li&gt;&#xA;&lt;li&gt;The stretched-out horizontal tail is also less effective than a smaller single surface with more chord and more distance from the center of gravity.&lt;/li&gt;&#xA;&lt;li&gt;The compact layout provides little pitch or yaw damping. I wonder what the ride qualities in gusty weather are.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I would expect that a more conventional layout along the lines of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Akaflieg_Stuttgart_FS-28_Avispa&quot; rel=&quot;nofollow noreferrer&quot;&gt;fs-28&lt;/a&gt; would be even more efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5RPFQ.jpg&quot; alt=&quot;Akaflieg Stuttgart fs-28 in flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Akaflieg Stuttgart fs-28 in flight (picture &lt;a href=&quot;http://www.flugzeug-bild.de/1024/private-fs-28-avispad-ekfsflugplatzfest-karlsruhe-forchheim180910--24892.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-11-20T20:06:50.230" LastActivityDate="2019-11-20T20:06:50.230" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="3468" PostTypeId="2" ParentId="3455" CreationDate="2014-04-18T04:39:52.657" Score="15" Body="&lt;p&gt;It's been several years since I worked at United's flight training center, but if my memory serves me, it is there in case the system is receiving input that the pilot wants to exclude. As was explained to me, an example of this would be the other pilot becoming incapacitated, with their body leaning against the sidestick. In this case, one would want to use the Priority Takeover button to eliminate the other pilot's input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Captain Sullenberger's case, it is likely that he wanted to ensure that First Officer Skiles wasn't providing any control inputs that would work against his control inputs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, it is also my understanding that such functionality is not useful in a &quot;hostile takeover&quot; event, since the other pilot can also attempt a priority takeover (or use physical force, due to the close proximity of the two pilots). &lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="524" LastEditDate="2014-04-22T22:22:32.777" LastActivityDate="2014-04-22T22:22:32.777" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3469" PostTypeId="2" ParentId="3458" CreationDate="2014-04-18T04:59:25.103" Score="6" Body="&lt;p&gt;One of the unique aspects of Airbus fly-by-wire aircraft is that the sidesticks provide NO feedback. Because of this, the planes have an automatic trim system. Once the aircraft is pitched to a desired attitude, the pilot will then release the control stick and the aircraft will continue to fly at the selected attitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Correspondingly, if a pilot desires to reduce the pitch, they must push the stick forward to do so. In an Airbus (unlike most other aircraft), a pilot doesn't manipulate trim at all (except in non-normal situations). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside, in the normal flight regime, Airbuses provide automatic protections from unsafe attitudes. Thus, if a pilot desires maximum rate of climb (that is possible in the current configuration), he can simply pull the sidestick all the way back. The computer will automatically keep the aircraft from exceeding maximum load factor and/or critical angle-of-attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the other part of your question, the lateral stick movement is likely due to turbulence. Control inputs in large aircraft tend to be more pronounced than smaller aircraft (due to slower aircraft reaction times).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-04-18T14:01:43.580" LastActivityDate="2014-04-18T14:01:43.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3470" PostTypeId="2" ParentId="3466" CreationDate="2014-04-18T05:01:37.760" Score="6" Body="&lt;p&gt;Everything is available for a price, and you don't need Google's help: You can get the &lt;a href=&quot;http://www.boeing.com/boeing/commercial/aviationservices/fleet-services/maintenance-engineering/toolbox.page&quot;&gt;Boeing Maintenance Performance Toolbox&lt;/a&gt; right from Boeing if you contact them.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You can also Google around and get PDFs of Boeing maintenance documents but these would be from unofficial/unauthorized sources (at least one Boeing maintenance manual made it onto Wikileaks).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Boeing likely holds a copyright on their maintenance documents obtaining them from an unofficial/unauthorized source would be an infringement on that copyright.&lt;br&gt;&#xA;More importantly you can't guarantee documents from an unofficial source are correct, current, and unmodified. If you intend to use the document for any aviation purposes (like performing maintenance on an aircraft) you would want to be absolutely certain they are the latest approved revision from Boeing.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-18T05:01:37.760" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3471" PostTypeId="1" CreationDate="2014-04-18T06:02:10.057" Score="10" ViewCount="1180" Body="&lt;p&gt;Since pilots are permitted to communicate in their own language to eachother in the cockpit, and to ATC in their own country, it stands to reason that some warning systems like &lt;a href=&quot;http://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TCAS&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_proximity_warning_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TAWS/EGPWS&lt;/a&gt; might say &quot;te laag, terrein!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen some Russian planes with everything written in Russian in the cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HOFxF.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any aircraft have systems that give spoken warnings or callouts in languages other than English?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are any planes built with the option to change the spoken language? E.g. an Airbus talking French?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-09T18:51:00.147" LastActivityDate="2015-04-09T18:51:00.147" Title="Do any aircraft systems give spoken warnings in a language other than English?" Tags="&lt;cockpit&gt;&lt;fwc&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3472" PostTypeId="2" ParentId="3462" CreationDate="2014-04-18T06:05:20.003" Score="17" Body="&lt;p&gt;Lufthansa does. They actually prefer people they can train themselves, so they never learned things which Lufthansa considers bad practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This becomes impossible if the airline grows quickly. Therefore, all the new carriers (Etihad or Vueling, for example) need to rely on hiring certified pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://lufthansa-pilot.de&quot;&gt;Lufthansa-Pilot.DE&lt;/a&gt; (only in German but speaking German is a requirement anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks, Danny, for the link. Lufthansa has now adopted English as their corporate language, so I wonder how firm the German language requirement still is.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-04-20T08:32:26.783" LastActivityDate="2014-04-20T08:32:26.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3473" PostTypeId="1" CreationDate="2014-04-18T06:15:46.213" Score="6" ViewCount="257" Body="&lt;p&gt;&lt;a href=&quot;http://atwonline.com/open-skies/european-commission-gets-tough-fab-implementation&quot;&gt;Air Transport World&lt;/a&gt; is reporting that the European Commission has initiated legal proceedings against Germany, Belgium, France, the Netherlands and Luxembourg; for not implementing FABs by the deadline. A quote says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FABs are a cornerstone of the SES initiative and are intended to reduce the capacity, cost and environmental constraints that continue to dog Europe's fragmented air traffic management (ATM) system by establishing common airspace blocks arranged around traffic flows rather than state boundaries.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What exactly are SES and FABs, in laymans terms?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2016-09-18T06:10:40.297" Title="What are the Single European Sky (SES) and Functional Airspace Blocks (FABs)?" Tags="&lt;airspace&gt;&lt;eu&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3474" PostTypeId="1" AcceptedAnswerId="3481" CreationDate="2014-04-18T07:15:58.360" Score="12" ViewCount="9433" Body="&lt;p&gt;As we see trains nowadays with sockets for you to plug your laptop into, as well as Wi-Fi on-board both trains and planes, I'm wondering why you don't see electrical outlets on planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any airlines have sockets in the cabin? How about in first class?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="1467" LastEditDate="2016-03-31T13:49:26.387" LastActivityDate="2016-03-31T13:49:26.387" Title="Do commercial aircraft have electrical outlets?" Tags="&lt;airliner&gt;&lt;passenger&gt;&lt;electrical-system&gt;&lt;electronics&gt;" AnswerCount="6" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3475" PostTypeId="2" ParentId="3462" CreationDate="2014-04-18T10:31:56.947" Score="3" Body="&lt;p&gt;Consider the case in Hong Kong.&#xA;Both Cathay Pacific and Dragonair offers cadet pilot programmes for people with no prior flying experience. You will be sponsored to attend the flight school at Adelaide and be hired upon graduation. &lt;/p&gt;&#xA;" OwnerUserId="1706" LastActivityDate="2014-04-18T10:31:56.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3476" PostTypeId="2" ParentId="3474" CreationDate="2014-04-18T11:24:48.547" Score="3" Body="&lt;p&gt;They are universally available since maybe 10 to 15 years, but only in Business and First, and normally would accept both US and European plugs. In Economy you are out of luck, but if you consider that most airlines have reduced Economy seating pitch to the minimum 31&quot;, laptop use is near impossible there, anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen one instance a few years ago on an older 747 where they had a proprietary socket and would hand out adapters for the different laptops. Naturally, the adapter kit was of the same age and unusable on some modern laptops.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-18T11:24:48.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3477" PostTypeId="2" ParentId="2871" CreationDate="2014-04-18T14:00:20.830" Score="13" Body="&lt;p&gt;After all these answers with Imperial Units, let me explain it with SI units, starting from first principles. R is the radius, v the flight speed, m the mass, g the gravitational constant, &amp;Phi; is the bank angle and L the lift.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/H9Dp9.png&quot; alt=&quot;Airplane in banking flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift needs to be equal to the weight (m&amp;middot;g) and the centrifugal force (m&amp;middot;&amp;omega;&amp;sup2;&amp;middot;R = m&amp;middot;$\frac{v^2}{R}$), so&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L = \sqrt{(m{\cdot}g)^2 + (m{\cdot}{\omega}^2{\cdot}R)} = \frac{\rho}2{\cdot}v^2{\cdot}c_L{\cdot}S$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with &amp;rho; the air density, $c_L$ the lift coefficient and S the surface area of the wing. Now convert so you get v:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v = \sqrt[\Large{4\;}]{\frac{(m{\cdot}g)^2}{{(\frac{\rho}2{\cdot}c_L{\cdot}S)^2} - (\frac{m}{R})^2}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you can see that the nominator cannot become zero or less, which gives you the minimal radius for a given speed and maximum lift coefficient $c_{L max}$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$R ≥ \frac{2{\cdot}m}{\frac{\rho}2{\cdot}c_{L max}{\cdot}S},$$ and generally: $$R = \frac{2{\cdot}m}{\frac{\rho}2{\cdot}c_{L}{\cdot}S} = \frac{v}{\omega} = \frac{v^2}{g\cdot\sqrt{n_z^2-1}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is like a &quot;radius barrier&quot;: Turns cannot be flown tighter than that. This is due to the increase in centrifugal force which comes from flying steeper turns. The steeper the turn, the faster you must fly to create enough lift to compensate both weight and centrifugal force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does still increase is your angular velocity &amp;omega;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$${\omega} = \frac{v}{R} = \frac{g{\cdot}tan{\Phi}}{v} = \frac{g\cdot\sqrt{n_z^2-1}}{v}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below I have plotted them for a glider. You can clearly see the radius barrier at 40 m. Trust me, it looks just the same for an airliner, only the numbers are bigger.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/NI4EU.png&quot; alt=&quot;plot for speed, nz and omega over radius&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a quick formula for estimating the radius, you need to use the square of airspeed, so this is not a simple linear relationship. For a turn with 30° bank ($n_z$ = 1.15), the denominator of the radius equation is about 4, so to calculate the turn radius in meters, divide the square of airspeed by 4 or take the square of half your airspeed in meters per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the turn rate in degree per second, divide 220 by your airspeed in meters per second. Flying slower allows for a higher turn rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the other extreme: Hypersonic aircraft need &lt;strong&gt;lots&lt;/strong&gt; of space for maneuvering. I have here some values, just for fun:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/YoAmR.png&quot; alt=&quot;table of radii over speed&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high speed makes this almost tolerable, after all, a half turn at Mach 6 and 2 g takes only 336 seconds, that's under 6 minutes. Airliners bank to only 30° or less, so the first column is valid if you fly your hypersonic vehicle like an airliner.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-04-30T15:54:16.943" LastActivityDate="2018-04-30T15:54:16.943" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3478" PostTypeId="2" ParentId="3450" CreationDate="2014-04-18T14:21:29.233" Score="5" Body="&lt;p&gt;There are &lt;a href=&quot;http://www.skybrary.aero/index.php/Aircraft_Certification_for_Bird_Strike_Risk&quot; rel=&quot;nofollow&quot;&gt;multiple various requirements&lt;/a&gt;, for instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;After &quot;swallowing&quot; a smallish goose (formally up to 3.65kg) the engine must still pull at least half of the thrust for at least 14 minutes, and must not become dangerous for the plane (no fire, no uncontained failure).&lt;/li&gt;&#xA;&lt;li&gt;After ingesting a flock of ducks (16 birds no more than 0.85kg each) the engine must still work for about 20 minutes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are also requirements for various sizes and number of birds in between, and some requirements depend on the inlet size. In general, seems that after the bird strike the engine is required to stay safe and even work for some time, but not for long. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="946" LastEditDate="2014-08-14T00:34:37.137" LastActivityDate="2014-08-14T00:34:37.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3479" PostTypeId="2" ParentId="3458" CreationDate="2014-04-18T14:32:44.147" Score="5" Body="&lt;p&gt;For each takeoff in a jet like this, there is a target airspeed that is used during the climb just after takeoff.  When the nose of the aircraft is first lifted, a target pitch setting is used which should get close to that airspeed.  After things start to stabilize, corrections are made to the pitch in order to capture and maintain the desired airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pay close attention to the Primary Flight Display during the takeoff: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.oaviao.com/pesquisa_codigo_empresas/manuais_voo/performance_airbus/images/11.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nBu0s.gif&quot; alt=&quot;A330 PFD&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will see that the pilot is simply making corrections in order to maintain the desired airspeed and bank angle:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For pitch control (forward and aft stick movement) he is correcting to maintain the airspeed.  If you watch the video carefully, you will notice that each time that the trend vector on the left side of the airspeed line moves up (indicating that the airplane will increase in speed if no changes are made), the pilot pulls back on the stick (and vice-versa) in order to maintain the airspeed.  It looks to me like he is pulling back just as much as pushing forward for most of the initial takeoff, until he starts accelerating just before the 3:00 mark.&lt;/li&gt;&#xA;&lt;li&gt;For bank control (left and right stick movement) he is correcting to maintain wings level until he starts the turn just before the 3:00 mark.  Watch the yellow triangles at the top of the blue part of the attitude indicator, and you will see that if they don't match up (like in the picture above) that he makes a correction with the stick to line them back up again.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This particular flight must have had turbulence because both the bank and the airspeed were jumping around a fair amount, requiring constant adjustments on the part of the pilot.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-18T14:32:44.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3480" PostTypeId="2" ParentId="3474" CreationDate="2014-04-18T14:42:58.620" Score="5" Body="&lt;p&gt;Some EMB-145 models have a 120v AC outlet mounted in the cabin just below the cockpit door.  This was powered by an inverter (EMB-145 is 100% DC busses).  It wasn't for passenger use (primarily for cleaning crews) and I didn't trust the power coming out of it enough to plug in a laptop, though we sometimes did charge our phones with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some larger airplanes have 120v AC in the cabin mounted at a subset of seats.  I can't recall which airlines, but I have been in a 757 and a corporate CRJ-700 that had this kind of power installed.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-18T14:42:58.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3481" PostTypeId="2" ParentId="3474" CreationDate="2014-04-18T14:59:03.153" Score="11" Body="&lt;p&gt;This depends on the airline, but to answer your question:  Yes, some airlines do have electrical outlets in the cabin.  It seems that since the FAA relaxed the rules on portable devices that the airlines are seeing the need to add them to more of their fleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;US Airways has a &lt;a href=&quot;https://www.usairways.com/en-US/traveltools/intheair/businesstools/laptop.html&quot; rel=&quot;noreferrer&quot;&gt;Business Tools webpage&lt;/a&gt; which tells which of their aircraft have outlets.  There are some in both coach and first class.&lt;/li&gt;&#xA;&lt;li&gt;United has an &lt;a href=&quot;https://www.united.com/web/en-US/content/travel/inflight/connectivity/default.aspx&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Inflight connectivity and power&lt;/em&gt; webpage&lt;/a&gt; whichs shows that a lot of their fleet has electrical outlets and more are coming.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are different types of outlets, and some of them require an adapter to use while others don't.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="3504" LastEditDate="2014-12-19T02:39:58.147" LastActivityDate="2014-12-19T02:39:58.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3482" PostTypeId="2" ParentId="3474" CreationDate="2014-04-18T15:04:02.007" Score="5" Body="&lt;p&gt;To answer your question of &quot;why don't you see them,&quot; I think it comes down to power requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned, new-ish first/business class generally will have outlets available. You can explore different aircraft &lt;a href=&quot;http://www.seatguru.com/articles/in-seat_laptop_power.php&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason it's not available in every seat is capacity. If you have 150 people pulling 75W, that's 11.25 kW. On a 737 NG, each of the two generators is rated at 90KVA. However, they need most of that power to run the radio equipment, avionics, lights, galleys, window heat, entertainment system, and everything else on the plane that runs on electrical power. So besides a possible upgrade of the generators/power system, this also adds the weight of running cables and having outlets at every seat. It's a lot easier to do that sort of thing on a train car, where it doesn't have to fly and can get power from the locomotive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find more about the 737 electric system &lt;a href=&quot;http://www.b737.org.uk/electrics.htm&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-04-18T15:04:02.007" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3483" PostTypeId="1" CreationDate="2014-04-18T15:05:11.347" Score="20" ViewCount="2971" Body="&lt;p&gt;I've never seen a 727's aft stairs open, but presumably, based on an Wikipedia image and common sense, they do reach the ground when the aircraft is on the ground. Furthermore, (as I understand it), airliners land with a positive pitch, which means that assuming a level runway, the rear of the aircraft will touch down first. However, this suggests that if the aft stairs of the 727 were open during landing, they would impact the ground during landing and, given the pitch, do more than scrape the ground and cause damage to the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;However, &lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper&quot; rel=&quot;noreferrer&quot;&gt;DB Cooper's jump&lt;/a&gt; left the aft stairs open, and (as far as I can tell) it seems that the landing was uneventful besides the stress of having a hijacker potentially on board (although it's quite understandable if no one made any record of it, given there were slightly more important things to deal with).&lt;/p&gt;&#xA;&lt;p&gt;If DB Cooper's flight did land without damage, why is that—did the 727's aft stairs not fully touch the ground? If the stairs did impact the ground, was there sufficient damage to require repairs?&lt;/p&gt;&#xA;&lt;p&gt;(I meant this question to be more about the 727 than DB Cooper, but since his was the only landing with stairs open, there wasn't much room for speaking in general terms).&lt;/p&gt;&#xA;" OwnerUserId="1934" LastEditorUserId="62" LastEditDate="2020-09-15T16:51:04.553" LastActivityDate="2021-01-08T18:51:21.157" Title="Did DB Cooper's aircraft land safely with the aft stairs open?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;boeing-727&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="3484" PostTypeId="1" AcceptedAnswerId="3486" CreationDate="2014-04-18T16:49:30.297" Score="8" ViewCount="3382" Body="&lt;p&gt;Yeah, it sounds like two questions, but I suspect the answers are very closely linked (or maybe even have the same answer.)  I was told in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3432/what-are-the-properties-of-a-good-general-aviation-training-aircraft/3434?noredirect=1#comment6786_3434&quot;&gt;this question&lt;/a&gt; that trainer planes are often designed to be stall or spin resistent.  I was wondering how this is accomplished?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does one make a wing resistant to stalls or spins?  Or perhaps, more generally, how does one make a wing predictable and stable?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-10-20T06:57:17.557" Title="How is a wing designed to be stall or spin proof?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3485" PostTypeId="2" ParentId="3484" CreationDate="2014-04-18T17:08:06.400" Score="4" Body="&lt;p&gt;There are several ways a small airplane can be designed to be resistant to stalls and spins. Both cases are somewhat similar in that they both involve cases where the aircraft's controls are rendered ineffective, and a stall can lead to a spin if not properly corrected. While a stall is certainly largely dependent on the aircraft's wing, both stalls and spins also depend on the whole aircraft's geometry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is some interesting information &lt;a href=&quot;http://www.iconaircraft.com/faq-spin-resistance.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; about spins and stalls. Wikipedia also has a good article about &lt;a href=&quot;http://en.wikipedia.org/wiki/Spin_%28aerodynamics%29&quot; rel=&quot;nofollow&quot;&gt;spins&lt;/a&gt;. There are FAA requirements for single-engine planes in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/78909ED5A6DBEB9485256687006D0568?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;FAR 23.221&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to maintain control in a stall, devices like vortex generators can be installed upstream of the ailerons. If the air flow separates from the wing before the ailerons, the air is no longer flowing over the control surfaces, resulting in a loss of control. The vortex generators help the flow to remain attached past the ailerons, helping them to stay effective at high angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides vortex generators, the wing itself can be designed for a similar effect. The inboard sections can be designed to stall before the outer sections, so the lift decreases but the outer sections will still provide lift and control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft can also be designed such that the elevator does not have enough authority to fully stall the plane, or not any further than the ailerons will still have authority. The effect of the elevator will also depend on the airplane's center of gravity, which has a suggested range but is determined by the operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A spin is related to the geometry of the airplane, where the air flow past the wing &quot;blanks&quot; the tail surfaces. This geometry can be arranged such that it would be more difficult to create spin conditions. However, conventional aircraft designs tend to inherently be susceptible to this. Most aircraft are certified as &quot;spin recoverable&quot;, meaning that the aircraft will spin, but the pilot should be able to stop a spin with the proper control inputs. Improving the plane's stall characteristics will also help prevent spins from happening.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-18T17:19:41.190" LastActivityDate="2014-04-18T17:19:41.190" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3486" PostTypeId="2" ParentId="3484" CreationDate="2014-04-18T17:17:42.203" Score="16" Body="&lt;p&gt;It's really two separate questions. In both cases the wing is not alone, it is the whole configuration, especially when it comes to spins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A stall is unavoidable. At some point the airflow over the wing will start to separate, and if this flow separation is extensive enough to limit the increase in lift with increasing angle of attack (AoA), the wing stalls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make stall characteristics benign, the outer wing should still have mostly attached flow to enable the ailerons to correct roll angle. If the stall starts on one wingtip, causing a local loss of lift, the aircraft will roll uncontrollably. The downward movement of the wing tip during the rolling motion increases angle of attack further, thus making the stall unrecoverable. You achieve roll control by using washout at the wingtips and/or by using airfoils with a higher maximum AoA, eg. by using slats on the outer wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second condition is a gradual flow separation, starting from the trailing edge. Old five-digit NACA airfoils had a nasty stall characteristic with flow separation starting from the leading edge, resulting in a sudden drop of lift. This is achieved by designing the upper surface with an appropriate chordwise pressure distribution. Then the loss of lift over AoA will be gradual, giving the pilot the opportunity to recover easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases, the tail (or in canards the main wing) needs to remain in the attached flow regime to enable pitch control and pitch damping. In addition, the vertical position of the tail should be slightly lower than the wake from the separated flow, still close enough to have some turbulence hitting the elevator (so that the pilot feels the stall with the stick/yoke), but low enough that the airplane will not enter a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8022/what-is-a-deep-stall-and-how-can-pilots-recover-from-it/8027#8027&quot;&gt;deep stall&lt;/a&gt; (where the wing is fully separated and the tail in the wake of the wing, which reduces control authority to a point where the pilot cannot pitch down anymore).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinning needs a fuselage with some mass along the length. The rotation of this mass at a high AoA produces a pitch-up moment which is needed to stabilize the spin. The tail must be able to produce the remaining pitching moment and a yawing moment to stabilize the spin, but also to end it when the pilot so wishes. For this, it is important that the rudder is not in the wake of the horizontal tail. The deHavilland Tiger Moth has two aluminum strakes ahead of the empennage; without them a stall is unrecoverable because the rudder authority is not sufficient. To &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin/8590#8590&quot;&gt;end a spin in the F-14&lt;/a&gt;, the all-flying tailplanes had to be pulled all the way to their minimum angle of -70°, so they would not obstruct the flow to the two rudders. Only when the pilots would pull, they could end the spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to be clear: Normally you need to push to end the spin. Especially in gliders with their relatively small rudders and large wing inertia, this will put most of the wing back into the normal flow region, and roll damping will stop the rotation. This ends the inertial pitch-up from the fuselage, and the aircraft can be recovered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In more fuselage-dominated configurations, you end the spin by applying rudder against the spin direction. This reduces the rotation, reducing the inertial pitch-up and allowing the airplane to recover to normal AoAs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the stall, a spin is not always possible. Sometimes, especially at forward center-of-gravity locations, the pitch authority will not be sufficient to stabilize the spin. You can stall and apply rudder, but the airplane will only enter a spiral dive. Especially on jets the forward fuselage is a major factor in spins, because it produces a wake at high AoA which stabilizes the spin. Details in the shape of the fuselage will determine if the wake is sufficient to enable spins. This is a complex topic - sorry, but this scope makes it hard to get into more details.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-05-01T22:36:06.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3487" PostTypeId="2" ParentId="3483" CreationDate="2014-04-18T17:27:24.193" Score="9" Body="&lt;p&gt;I do not think they landed with the airstairs down: The airstairs are powered to get them back up since they are heavy, and this feature can be operated from inside the aircraft as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following answer is of &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20070408223808AAnwqQw&quot;&gt;Yahoo answers&lt;/a&gt; and while I can't confirm is accuracy, it sounds very plausible:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are 2 control handles for the airstairs on a B727, one under a&#xA;  panel on the lower fuselage right beside the stair forward hinge&#xA;  point, and one at the top of the stairs behind a panel on the left&#xA;  side which can only be accessed when the rear cabin door is open.&#xA;  Because the cabin door can only be opened when the aircraft is&#xA;  unpressurized, this usually would prevent its actuation in flight.&#xA;  However, after the D B Cooper hijacking a device was added referred to&#xA;  as an anti-hijack vane that would swing over when the aircraft was in&#xA;  flight and prevent the door opening. To &lt;strong&gt;close the door either an&#xA;  electric hydraulic pump has to be turned on in the cockpit, or a hand&#xA;  pump beside the lower control operated while either handle is held to&#xA;  the close position.&lt;/strong&gt; The door will free fall open without hydraulic&#xA;  pressure, but the support arms may have to be pushed to an overcenter&#xA;  position.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Assuming that the air stairs were deployed, it may be that the force of the airflow passing by would have been sufficient to spare the stairs from a tailstrike. The stairs have a large surface area and moving at perhaps around 100 knots when the nosewheel touches down would still generate a considerable force to push them into the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term deployed may also suggest that the airstairs may have been damaged and uable to retract the whole way, leaving it halfway stuck but still out of tailstrike range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft was empty at the time which would have helped in either situation.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="64" LastEditDate="2014-04-18T23:07:27.720" LastActivityDate="2014-04-18T23:07:27.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3488" PostTypeId="2" ParentId="2252" CreationDate="2014-04-18T18:18:14.977" Score="16" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292#9292&quot;&gt;Sweepback helps a lot&lt;/a&gt;, and the rest is achieved with drag devices near the wingtips.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5Ukkf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Ukkf.jpg&quot; alt=&quot;Northrop B-2 in flight&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(Source: &lt;a href=&quot;http://www.aerospaceweb.org/aircraft/bomber/b2/pics01.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;aerospaceweb.org&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;Did you notice that the B-2 has split ailerons, and they are partially opened during flight? Their drag pulls the wingtip back, and in combination with sweep the forward wing in yaw will have a longer lever arm, so the same drag produces a bigger stabilizing yawing moment.&lt;/p&gt;&#xA;&lt;p&gt;Differential thrust is not available on gliders, and there are lots of flying wing gliders. Horten III and IV, Fauvel AV-36 and the SB-13 are some examples. The Hortens used speed brakes near the wingtips, and the SB-13 has rudders with differential deflection (70° outwards, 20° inwards) on its winglets to increase the yawing moment.&lt;/p&gt;&#xA;&lt;p&gt;Directional control is no problem with flying wings, even though directional stability becomes weak at high speed when induced drag is low. Flutter and a low &lt;span class=&quot;math-container&quot;&gt;$c_{L max}$&lt;/span&gt; are the real drawbacks. &lt;a href=&quot;https://aviation.stackexchange.com/questions/76773/what-are-the-disadvantages-of-a-tailless-ultralight-design/76782#76782&quot;&gt;Ground handling, landing characteristics&lt;/a&gt; and payload space are others, but can be overcome somewhat.&lt;/p&gt;&#xA;&lt;p&gt;And flat spins are not possible with flying wings. Their spin modes are all fairly steep due to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin/8590#8590&quot;&gt;lack of a strong inertial moment from the lengthwise distribution of masses&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-04-20T16:07:54.007" LastActivityDate="2021-04-20T16:07:54.007" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="3489" PostTypeId="1" CreationDate="2014-04-18T19:47:48.967" Score="9" ViewCount="2360" Body="&lt;p&gt;When flying VFR, pilots are to stay free of clouds, which includes a minimum of 3 miles visibility, and 2,000 feet laterally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet, I've seen some youtube videos where it appears the pilot gets too close to a &quot;cotton ball&quot; (a small, isolated cloud) simply because it is along his flight path. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is a very small, very isolated cloud, and you can see all the way around it, and have had good visibility on it for awhile as you approach, you know its not a &quot;threat&quot;, right? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose the FAA could violate you if you approach a cotton ball, but other than that, is there any reason to deviate and go slaloming around the sky just to keep distance from FEW clouds?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="14957" LastEditDate="2017-06-02T16:56:12.483" LastActivityDate="2017-06-02T16:56:12.483" Title="Are VFR pilots required to avoid an isolated cumulus cloud like any other cloud?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;weather&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3490" PostTypeId="2" ParentId="3489" CreationDate="2014-04-18T20:00:20.393" Score="14" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I suppose the FAA could violate you if you approach a cotton ball, but other than that, is there any reason to deviate and go slaloming around the sky just to keep distance from FEW clouds?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aside from the legal reasons, keeping a healthy distance away from clouds is a Good Thing because other aircraft, birds, or alien spacecraft may pop out of them. Mid-Air collisions are no fun for anyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as going &quot;slaloming around the sky&quot;, there's generally no reason to do that to avoid clouds:&lt;br&gt;&#xA;If you're respecting the cloud clearance requirements (or at least &lt;a href=&quot;https://aviation.stackexchange.com/questions/577/how-can-i-tell-how-far-i-am-from-a-cloud&quot;&gt;the intent behind them&lt;/a&gt;) you shouldn't be getting close enough to clouds that you have to aggressively maneuver to avoid them - you've got plenty of distance to decide what you want to do.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember too that you've got 3 dimensions to work with: If we're only talking about a &quot;puffy cotton-ball&quot; or two you can always climb above or descend below them and stay on-course, or if they're all lined up inconveniently right along your flight path just offset your track a little bit (no reason to keep zig-zagging if a mile left or right of course keeps you clear).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-04-18T20:00:20.393" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3491" PostTypeId="2" ParentId="3459" CreationDate="2014-04-18T20:06:52.413" Score="6" Body="&lt;p&gt;Apparently, it is catching on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing &lt;a href=&quot;http://www.boeing.com/boeing/commercial/777family/background/back6.page&quot;&gt;mentions&lt;/a&gt; it is unique to &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777&quot;&gt;777&lt;/a&gt;, probably the first one to have cameras.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A feature unique to the 777-300ER and 777-300 flight deck is the&#xA;  &lt;strong&gt;Ground Maneuver Camera System (GMCS)&lt;/strong&gt;, designed to assist the pilot in&#xA;  ground maneuvering of the 777-300 with camera views of the nose gear&#xA;  and main gear areas. The cameras are on the leading edge of the left&#xA;  and right horizontal stabilizers and the underside of the fuselage and&#xA;  are used during ground maneuvering. The images are displayed at the&#xA;  Multi-Functional Display positions in the flight deck in a three-way&#xA;  split format.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Boeing also has patents for this: &lt;a href=&quot;http://www.google.com/patents/US6405975&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.google.com/patents/EP0980828A1&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure if these patents prevents others to have them, because many business jets already had cameras on, and this trend is catching on even for &lt;a href=&quot;http://www.ainonline.com/aviation-news/aviation-international-news/2011-02-25/inflight-cameras-provide-birds-eye-view-passengers&quot;&gt;passengers on commercials plans&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus mentions this too for &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A340#A340-500&quot;&gt;A340&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A340-500 and −600 has taxi cameras to help the pilots during&#xA;  ground maneuvers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess it has &lt;a href=&quot;http://www.cae.com/civil-aviation/simulation-products/cae-visual-solutions/image-generators/&quot;&gt;several different names&lt;/a&gt;, probably because of pending patents etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as the recording goes, I could not find any information.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-04-18T20:06:52.413" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3492" PostTypeId="2" ParentId="1873" CreationDate="2014-04-19T02:49:53.563" Score="1" Body="&lt;p&gt;The asterisk informs the pilot that this only applies to the Non-Precision LOC approach.  The bolded V is indicating this is a Visual Decision Point (VPD).  See &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronatical Charts Users Guide&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;On some IAPs the decent rate required to reach the minimum decent altitude (MDA) by the missed approach point (MAP) at a distance from the threshold that will allow landing in the touchdown zone will be informed by a VDP. See Descent Rates and Glide Paths for Non-Precision Approachs in the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Procedures Handbook&lt;/a&gt; in Chapter 4 (4-37 in 2012) for a discussion of the corresponding math.&lt;/p&gt;&#xA;&lt;p&gt;In short when on the 19L ILS/LOC between SHAKE and ROGGE you either be above 1900 or on glideslope for obstacle clearance.  Interestingly if you look at the VFR Sectional and plot that approach you'll see that this portion is over the water but in the departure for 30 28l and 28R for OAK.&lt;/p&gt;&#xA;" OwnerUserId="1977" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-30T14:43:17.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3493" PostTypeId="2" ParentId="3489" CreationDate="2014-04-19T06:59:01.503" Score="5" Body="&lt;p&gt;The rules are there for a reason, and yet they are broken regularly. Here in Europe, on a nice day for cross-country glider flying, every pilot climbs up until he/she almost touches the cloud. Thermals go up into big cumulus clouds (your puffy little ones are baby cumulus - just wait, and some of them will become really big), and the center is normally higher than the fringes (the updraft is below the center and continues into the cloud, the fringes show downdraft - the rising air has to come down somewhere).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Updrafts get stronger the higher they are, so the last meters below the cloud give you the best energy increase, and the pilots use the last circle not for climbing, but for speeding up. Then they fly straight out from the thermal, through the puffy fringes and out into the open sky at high speed (for a glider, that is).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It just happens. A friend once told me that he was below a cloud, and right next to him a turboprop airliner descended from the cloud. However, that must have been a bad airliner pilot, because flying through a cumulus like this incurs a lot of avoidable turbulence.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-19T06:59:01.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3494" PostTypeId="1" CreationDate="2014-04-19T07:05:09.037" Score="5" ViewCount="903" Body="&lt;p&gt;What are the advantages/disadvantages of an autobrake system? In particular I am interested in the Fokker 100 system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have any studies been done for the F100 autobrakes and the affects that this system has on the landing gears?&lt;/p&gt;&#xA;" OwnerUserId="2154" LastEditorUserId="97" LastEditDate="2014-04-19T22:11:56.830" LastActivityDate="2014-04-29T13:27:37.517" Title="What are the pros &amp; cons of Autobrake?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;landing-gear&gt;&lt;braking&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3495" PostTypeId="1" AcceptedAnswerId="3498" CreationDate="2014-04-19T07:37:46.237" Score="12" ViewCount="1983" Body="&lt;p&gt;In an ATIS or AWOS/ASOS recording, is the reported altimeter setting corrected for temperature?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it must be, because on a hot day, the altimeter should still show correct field elevation. If it wasn’t corrected for temperature, then the reported field elevation could be badly wrong on a really hot or really cold day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;https://aviation.stackexchange.com/questions/3011/how-is-pressure-related-to-air-density/3035#3035&quot;&gt;This&lt;/a&gt; and other questions describe pressure and density more generally.)&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-04-19T22:08:16.367" Title="Is the altimeter setting corrected for temperature?" Tags="&lt;flight-instruments&gt;&lt;temperature&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3496" PostTypeId="2" ParentId="3495" CreationDate="2014-04-19T08:25:39.113" Score="-1" Body="&lt;p&gt;The altimeter is adjusted for air pressure, which is a function of temperature (and altitude). So the answer to your question is yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is why it is bad for an airport to be &quot;hot and high&quot; (think Phoenix in the summer), the high altitude is compounded with nearly 100°F (40C) temps, makes for very thin air.&lt;/p&gt;&#xA;" OwnerUserId="757" LastActivityDate="2014-04-19T08:25:39.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3498" PostTypeId="2" ParentId="3495" CreationDate="2014-04-19T09:57:54.843" Score="10" Body="&lt;p&gt;The reported altimeter setting, &lt;strong&gt;QNH&lt;/strong&gt;, is 'somewhat' corrected for temperature, in that it corrects for temperature error at the aerodrome elevation. This is the main difference between the more-meteorologicaly-inclined &lt;strong&gt;QFF&lt;/strong&gt; which does not contain this temperature correction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will still get altimeter errors because of the high/low temperature while being above (or below) the aerodrome  (about 40 ft for each 1000ft for each 10 degrees C), but the actual &lt;strong&gt;temperature error&lt;/strong&gt; at &lt;strong&gt;aerodrome level&lt;/strong&gt; will be &lt;strong&gt;0&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-04-19T09:57:54.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3499" PostTypeId="2" ParentId="3473" CreationDate="2014-04-19T10:18:42.490" Score="1" Body="&lt;p&gt;SES = Single European Sky Legal Framework. It started in 2004 when the EU Parliament and Council adopted Reg 549/2004 (framework regulation), 550/2004 , 551/2004 and 552/2004 (interoperability regulation). Also, a very important regulation was 219 which established EASA! (All these legislation is called SES I... amendments later came in place along a myriad of Implementing Regulations) which dealt mainly with What and How the Air Navigation Providers (ANSPs) must provide ANS services. This legislation aims at Uniting the National FIRs (Flight Information Regions) into BIGGER FIRs (Called FABs - Functional Airspace Blocks). Most of the operational advantages of FABs: Direct Routes, lower CO2 emissions and lower fuel burns for air companies are True and EU citizens will gain overall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since FABs will include the airspace of more sovereign nations, from a legal point of view, FABs need to be created with a Multilateral Agreement in the adjacent States. &lt;/p&gt;&#xA;" OwnerUserId="861" LastEditorUserId="861" LastEditDate="2014-04-22T05:42:20.700" LastActivityDate="2014-04-22T05:42:20.700" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3500" PostTypeId="2" ParentId="371" CreationDate="2014-04-19T12:21:13.340" Score="5" Body="&lt;p&gt;Another option that you can look at is the &lt;a href=&quot;http://www.gocivilairpatrol.com&quot;&gt;Civil Air Patrol&lt;/a&gt;.  They mostly do disaster reconnaissance flights, though they have several other aviation odd jobs they do for the government.  It  can be really helpful if you know how to use a &lt;a href=&quot;http://en.wikipedia.org/wiki/Digital_single-lens_reflex_camera&quot;&gt;DSLR&lt;/a&gt; style camera because most of their reconnaissance work is done with that type of camera.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-04-19T12:21:13.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3501" PostTypeId="2" ParentId="3494" CreationDate="2014-04-19T12:36:50.683" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Autobrake&quot;&gt;Autobrake&lt;/a&gt; is a smart system which basically implies that the pressure is applied to the brakes when a set of circumstances are reached, such as when the plane detects that it is on the ground and the thrust is in idle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are in principle only advantages with an autobrake system, since it reduces pilot workload during the moments after landings and reduces necessary runway to stop. While autobrake has what I know not been the reason for any accidents, the faulty computer logic of the computers in the autobrake and spoiler system contributed to a &lt;a href=&quot;http://en.wikipedia.org/wiki/Lufthansa_Flight_2904&quot;&gt;Lufthansa accident&lt;/a&gt; in 1993.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As I gather, the Fokker 100 autobrake will be activated when the thrust levers are commanded to idle reverse and the system is on. It has 5 settings: RTO (Rejected Takeoff), OFF and LO/MID/HI, the latter 3 representing the amount of automatic brake pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autobrake is closely related to the spoilers, which are simply a button on the Fokker 70/100. The direct effect of spoilers on the landing gear is that they are pushed harder down onto the runway (since the lift from the wings is disrupted), making the braking more effective early on during landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.webklik.nl/user_files/2012_01/343754/Printenverkeerdeshit.pdf&quot;&gt;Source&lt;/a&gt; (not very good but the best i could find)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-04-19T15:19:24.897" LastActivityDate="2014-04-19T15:19:24.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3502" PostTypeId="2" ParentId="2873" CreationDate="2014-04-19T15:22:12.380" Score="21" Body="&lt;p&gt;1948 year train crash in Wädenswil (Switzerland) probably explains why &quot;task-oriented interfaces&quot; may actually be dangerous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This train had the same control both to apply accelerate and decelerate with its electric engine, depending on the position of the separate switch. Indeed, you either accelerate or decelerate, never do both. Why to have two separate controls? A tiny switch looks enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once, on a steep decline, the driver failed to select the right position of this switch and applied full power instead of braking. 21 killed. If it would have had two very different controls for brake and acceleration, such a mistake would have been much less probable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, where practical, it may be better to have more controls that never change they function and always do (or display) the same.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2014-04-20T15:20:45.727" LastActivityDate="2014-04-20T15:20:45.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3503" PostTypeId="2" ParentId="3495" CreationDate="2014-04-19T16:03:52.600" Score="5" Body="&lt;p&gt;The given sea level pressure from an ATIS will reflect the local deviation from standard temperature such that your altimeter (which does not correct for temperature) displays field elevation on the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is important to note that the ATIS/AWOS/ASOS station is directly sampling station pressure, not sea level pressure, which must be derived.  The equation used to do this is the hypsometric equation and there is an assumption of temperature in the atmospheric layer between the ground and sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$(z_2 - z_1) = \dfrac{R\cdot\bar{T}}{g}\ln\left(\dfrac{p_1}{p_2}\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this equation $z_1$ is 0 m, $z_2$ is station elevation, $R$ is the gas constant for dry air, $\bar{T}$ is the average temperature between $z_1$ and $z_2$, $p_1$ is sea level pressure (hPa), $p_2$ is station pressure (hPa) and $g$ is acceleration due to gravity.  All are known except $p_1$ (assumptions about $\bar{T}$ are made from the lapse rate of the standard atmosphere and station temperature). Solving for $p_1$ yeilds:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$p_1 = p_2 \exp \left( \dfrac{g z_2}{R \bar{T}} \right)$$&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-04-19T19:05:10.543" LastActivityDate="2014-04-19T19:05:10.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3504" PostTypeId="2" ParentId="371" CreationDate="2014-04-19T16:20:36.097" Score="2" Body="&lt;p&gt;Flight training facilities such as CAE or FlightSafety have right seat programs.  You volunteer your time as the right seater during training events.  A great opportunity to learn a jet aircraft and become very familiar with emergency checklists, as well as, networking with a multitude of flight departments.  After a specified number of training events they will type rate you in that aircraft for no cost.  It may be an unpaid position but the experience and networking potential is priceless.  &lt;/p&gt;&#xA;" OwnerUserId="161" LastActivityDate="2014-04-19T16:20:36.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3505" PostTypeId="2" ParentId="3425" CreationDate="2014-04-19T17:30:45.583" Score="2" Body="&lt;p&gt;A jet engine can only &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_engine#Altitude_and_speed&quot; rel=&quot;nofollow&quot;&gt;accept air&lt;/a&gt; at around half the speed of sound. If the plane is flying faster, the inlet system needs to slow the air down before accelerating it again. Hence the higher the speed, the less thrust it can provide. It is not like a rocket engine that always pulls with comparable force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A plane needs to accelerate to Mach 25 or about to fly into orbit as a spacecraft, and this is only possible with a new type of engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Scramjet&quot; rel=&quot;nofollow&quot;&gt;Scramjet&lt;/a&gt; that is a jet engine, not a rocket, could probably do this. However this engine seems still under development and currently a rocket is required to accelerate to the speed under that this engine can even be started.&lt;/p&gt;&#xA;" OwnerUserId="917" LastActivityDate="2014-04-19T17:30:45.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3507" PostTypeId="1" AcceptedAnswerId="3508" CreationDate="2014-04-20T11:32:59.173" Score="11" ViewCount="3170" Body="&lt;p&gt;Is there a particular reason for which &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;noreferrer&quot;&gt;thrust vectoring&lt;/a&gt; is not used in airliners as it is with military aircraft besides weight and complexity factors?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that on military aircraft maneuverability is a core component but, by implementing this technique also on commercial airliners, wouldn't there be any benefit? For example one thing that comes into my mind would be reduction of stress on the tail of an aircraft at high speed/high altitude turns, thus potentially reducing maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option would be increased safety, whereas if maneuverability would be compromised by loss of the tail of the plane (for example &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587#Cause&quot; rel=&quot;noreferrer&quot;&gt;American Airlines 587&lt;/a&gt;), you would still have some sort of control, even though reduced, on the plane with directional thrust. &lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-02-19T19:40:40.627" LastActivityDate="2015-02-19T19:40:40.627" Title="Why is thrust vectoring not used on commercial jets?" Tags="&lt;airliner&gt;&lt;flight-controls&gt;&lt;military&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3508" PostTypeId="2" ParentId="3507" CreationDate="2014-04-20T13:35:30.517" Score="17" Body="&lt;p&gt;Thrust vectoring is for flying outside the &quot;normal&quot; envelope (which is characterized by attached flow). Airliners should really never leave this envelope, so they are perfectly fine with regular control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to add thrust vectoring, it would make most sense if the engines are at the back of the airplane. On most airliners, it is really better to put them on and ahead of the wings, because in this location they help both with flutter damping (mass ahead of the elastic line helps) and bending relief. Putting the engine mass right where lift is created is better than carrying stresses all around the airframe, which would be the case with rear-mounted engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The redundancy point is valid, but it would be more helpful to have redundant control surfaces, and this is exactly what airliners have. At some point, every airplane has to come down for a landing, which requires to throttle the engines. No thrust, no control!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most extreme case: If one tail surface breaks off, I wonder if thrust vectoring would be up to the job of trimming the aircraft even with cruise thrust. Not only have the raw forces to be sufficient, the reaction time to control setting changes has to be quick enough to suppress oscillations. I am sure, however, that thrust vectoring will certainly not suffice in all flight phases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust vectoring is perfect for situations at high angle of attack where you quickly want to point the nose of your aircraft at your adversary, so you get lock-on first. This is quite different from what an airliner has to do.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-20T13:35:30.517" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3509" PostTypeId="2" ParentId="3507" CreationDate="2014-04-20T20:34:37.220" Score="7" Body="&lt;p&gt;Thrust vectoring enables extreme maneuverability, airliners don't need that. Personally I don't want to be subjected to 9 Gs on the redeye from JFK to LHR! It's also very expensive technology to build and maintain, so your airfare would go up substantially. You also need a huge amount of power to make it work, so you'd have to fit afterburning engines to your commercial aircraft, which isn't workable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, differential thrust is already an option on airliners and other aircraft which have engines outboard on the wings. A B-52H lost its tail in the 1960s and made it back, the pilots made good use of differential thrust. UA232 used differential thrust after they lost hydraulics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's a technology that is expensive to implement, and isn't going to help prevent an accident. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-04-20T20:34:37.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3510" PostTypeId="1" CreationDate="2014-04-21T00:42:56.880" Score="15" ViewCount="5014" Body="&lt;p&gt;Watching &lt;a href=&quot;http://en.wikipedia.org/wiki/Jetstream_%28TV_series%29&quot; rel=&quot;noreferrer&quot;&gt;Jet Stream&lt;/a&gt;, about training to fly the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_CF-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;CF-18 Hornet&lt;/a&gt;, they comment that the jet was originally certified as a Navy plane, landing on aircraft carriers with an &lt;a href=&quot;http://en.wikipedia.org/wiki/Arresting_gear&quot; rel=&quot;noreferrer&quot;&gt;arresting cable&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, when landing on land, they land hard and fast and take a mile of runway to come to a stop; but during an emergency, they use the &lt;a href=&quot;http://en.wikipedia.org/wiki/Arrestor_hook&quot; rel=&quot;noreferrer&quot;&gt;tailhook&lt;/a&gt; which brings the jet to a stop after only 1,000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: why don't they always use this to land?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a short clip I've taken from the show:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/HvxwFJYipk0?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="1467" LastEditDate="2018-04-25T08:00:00.977" LastActivityDate="2018-04-25T16:02:31.080" Title="Why isn't the arresting hook always used on land?" Tags="&lt;military&gt;&lt;landing&gt;&lt;fighter&gt;&lt;arresting-gear&gt;" AnswerCount="7" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3511" PostTypeId="2" ParentId="1873" CreationDate="2014-04-21T06:31:57.027" Score="6" Body="&lt;p&gt;There are two situations to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;altitude restrictions before the Final Approach Segment&lt;/li&gt;&#xA;&lt;li&gt;altitude restrictions in the Final Approach Segment&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The first case is clear-cut. There is a risk of going outside altitude restrictions if you intercept the glideslope &lt;em&gt;before&lt;/em&gt; the published glide slope intercept point, except if noted otherwise. An &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2011/InFO11009.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Information for Operators article&lt;/a&gt; states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;when cleared for an ILS approach, do not descend below published&#xA;  step-down altitudes on an ILS final approach course, while &lt;strong&gt;outside&#xA;  the Final Approach Segment&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The main issue now is whether altitude restrictions are enforceable if you are on the glideslope, inside the Final Approach Segment and it does not state that it only applies to LOC approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Throughout the document, it never refers to stepdown fixes inside the Final Approach Segment, often stating that this is referring to &quot;outside the Final Approach Segment&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;nofollow&quot;&gt;A note in the AIM&lt;/a&gt; (after 5-4-5.b.4) also states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ILS glide slope is intended to be intercepted at the published&#xA;  glide slope intercept altitude. This point marks the PFAF and is&#xA;  depicted by the ”lightning bolt” symbol on U.S. Government charts.&#xA;  Intercepting the glide slope at this altitude marks the beginning of&#xA;  the final approach segment and ensures required obstacle clearance&#xA;  during descent from the glide slope intercept altitude to the lowest&#xA;  published decision altitude for the approach. Interception and&#xA;  tracking of the glide slope &lt;strong&gt;prior to the published glide slope&#xA;  interception altitude&lt;/strong&gt; does not necessarily ensure that minimum,&#xA;  maximum, and/or mandatory altitudes published for any preceding fixes&#xA;  will be complied with during the descent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To me, this implies that after the published glide slope interception altitude, that it is ensured that these altitudes will be met.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has also been &lt;a href=&quot;http://www.airlinepilotforums.com/technical/74029-stepdown-fixes-inside-faf.html&quot; rel=&quot;nofollow&quot;&gt;discussion on another forum&lt;/a&gt; about this, though the discussion doesn't provide an authoritative answer to this question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It seems weird that there is a discrepancy with some approaches having the &lt;code&gt;*&lt;/code&gt; past the PFAF, and a few that don't -- I'll take a further look to see if this is just an oversight or actually has specific meaning.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-04-24T15:08:43.547" LastActivityDate="2014-04-24T15:08:43.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3512" PostTypeId="2" ParentId="3510" CreationDate="2014-04-21T07:43:07.687" Score="21" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;There is a lot of stress placed on the airframe when you use the tailhoook. You can see the skin buckling in the picture below behind the landing gear. I'll admit, you probably wouldn't land intentionally with this sort of technique on land but if you catch the wire during the flare it could probably pull you down pretty hard. For these types of landing and it would be difficult to get it right every time.&lt;/p&gt;&#xA;&lt;p&gt;(&lt;em&gt;Like  I wrote in the comments, I do realize that the aircraft below has not yet caught the cable. When you flare, and you might catch the cable mid-air if you have a nose-high attitude, and slam down hard as it pulls you backwards and you loose lift, or you do a non-flare like carrier pilots, also very hard. IMO I think either would end up like the landing below.&lt;/em&gt;)&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/a/a1/US_Navy_E-2C_Hawkeye_carrier_landing_fuselage_detail.jpg&quot; alt=&quot;stress&quot; /&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You have no ability to control the aircraft and you end up stopping and rolling backwards on the runway. You can only be one aircraft at a time and you cannot roll off straight away, wasting time.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You'd have to have an arresting gear system and along with that more staff and maintenance.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At least on aircraft carriers, I believe the arresting cable has a limit of only 250 catches for safety reasons. Even if it the limit was greater on land, you'd have to have people changing the cables on a regular basis.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You'd still have to have conventional brakes which you could just as well use.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-12T19:50:20.010" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3513" PostTypeId="1" AcceptedAnswerId="3528" CreationDate="2014-04-21T11:21:06.690" Score="32" ViewCount="76283" Body="&lt;p&gt;Turboprop engines are &lt;strike&gt;more fuel efficient&lt;/strike&gt;&lt;sup&gt;1&lt;/sup&gt;, lighter for the same power, mechanically simpler and consequently more reliable.  They are also slightly easier to operate (no need to fiddle with mixture) and burn cheaper fuel. As a result they replaced piston engines in all transport aircraft long ago. So why didn't they find their way into small GA planes (basically everything above 8-10 seats uses turboprops, but in the 4-seat category, nothing does)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;Actually looks like I was mistaken. Reciprocating engines seem to be &lt;a href=&quot;http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption&quot;&gt;more efficient&lt;/a&gt;.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-04-22T04:50:42.167" LastActivityDate="2019-01-22T11:36:08.450" Title="Why don't small planes use turbine (turboprop) engines?" Tags="&lt;piston-engine&gt;&lt;turboprop&gt;" AnswerCount="14" CommentCount="10" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3514" PostTypeId="1" AcceptedAnswerId="3515" CreationDate="2014-04-21T13:25:21.150" Score="5" ViewCount="1399" Body="&lt;p&gt;How is the ATR 42/72 empennage considered? Is it a T-Tail or a cruciform tail?&#xA;From the image the elevators are placed quite high on the tail that they can be considered as a T-Tail but is it so?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the tail of a 727 the elevators are placed at the top of the tail but just leaving the space for the mechanism to move them, whereas on the ATR they are placed in a slightly lower position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any technical specifications and measurements that clearly define the difference between the two mentioned configurations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that cruciform means &quot;similar to a cross&quot; but it would be interesting to know, as previously mentioned, if there are specifics about this definition making it clear for everyone from a technical point of view. (briefly, when does a T-Tail become cruciform?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DSPNP.jpg&quot; alt=&quot;ATR Tail view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cjodl.jpg&quot; alt=&quot;727 Tail view&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="22726" LastEditDate="2019-09-25T21:21:30.367" LastActivityDate="2019-09-25T21:21:30.367" Title="Is the ATR empennage configuration considered a T-tail or a cruciform tail?" Tags="&lt;aircraft-design&gt;&lt;t-tail&gt;&lt;cruciform-tail&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="3515" PostTypeId="2" ParentId="3514" CreationDate="2014-04-21T14:05:56.500" Score="4" Body="&lt;p&gt;As far as technical specifications are concerned, some explanation is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Excerpt from &lt;a href=&quot;http://en.wikipedia.org/wiki/Empennage#Tailplanes&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; (formatting is mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;T-tail&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DESIGN: The horizontal stabilizer is mounted on top of the fin,&#xA;  creating a &quot;T&quot; shape when viewed from the front.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PURPOSE:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;T-tails keep the stabilizers out of the engine wake, and give better pitch control.&lt;/li&gt;&#xA;  &lt;li&gt;T-tails have a good glide ratio, and are more efficient on low speed aircraft.&lt;/li&gt;&#xA;  &lt;li&gt;However, T-tails are more likely to enter a deep stall, and are more difficult to recover from a spin.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;T-tails must be stronger, and therefore heavier than conventional&#xA;  tails. T-tails also have a larger radar cross section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Cruciform tail&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DESIGN: The horizontal stabilizers are placed midway up the vertical&#xA;  stabilizer, giving the appearance of a cross when viewed from the&#xA;  front.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PURPOSE: Cruciform tails are often used &lt;em&gt;to keep the horizontal&#xA;  stabilizers out of the engine wake&lt;/em&gt;, while avoiding many of the&#xA;  disadvantages of a T-tail.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In reference to your comparison between ATR 42/72 with Boeing 727, if we take out the difference in tail heights (ATR 42: &lt;em&gt;24' 11&quot;&lt;/em&gt;; ATR 72: &lt;em&gt;25' 1&quot;&lt;/em&gt;; B727: &lt;em&gt;34' 0&quot;&lt;/em&gt;), the position of horizontal stabilizer on vertical stabilizer is almost the same on these three airplanes. So they all match closely to a T-Tail configuration rather than a cruciform.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-04-21T14:05:56.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3516" PostTypeId="2" ParentId="3510" CreationDate="2014-04-21T15:27:57.183" Score="11" Body="&lt;p&gt;There are several reasons why arresting cables aren't used on land:&lt;/p&gt;&#xA;&lt;h2&gt;Stress&lt;/h2&gt;&#xA;&lt;p&gt;As Manfred noted, the stress that gets put onto a plane during landing is incredible.  According to &lt;a href=&quot;http://science.howstuffworks.com/aircraft-carrier4.htm&quot; rel=&quot;noreferrer&quot;&gt;HowStuffWorks &amp;quot;How Aircraft Carriers Work&amp;quot;&lt;/a&gt;, its not unusual for an aircraft to hit the deck at around 150 mph or about 67 mps.  Since they have less than 500 feet of runway (~150 meters), they must decelerate at an incredible speed to a standstill in about 2 seconds.  That equates to about 3.5 G's!  In addition, Navy pilot's are taught to push the throttle to max upon hitting the deck so that if they miss one of the 4 cables, they can still have enough speed to take off and try again.  This may now happen automatically as Chris S noted, I'm not certain.  This means that the aircraft has to undergo even more stress.  Navy planes must hit the deck so hard that its often compared to a controlled crash instead of landing and aircraft frames must be structurally modified to endure that type of stress.&lt;/p&gt;&#xA;&lt;h2&gt;Difficulty&lt;/h2&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/com/0425166821&quot; rel=&quot;noreferrer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tom Clancy's Carrier: A Guided Tour of an Aircraft Carrier&lt;/a&gt;, it is extremely difficult to catch the wires.  It is so difficult that Navy Pilots are often ranked on how often they hit the 2nd wire (considered to be the best).&lt;/p&gt;&#xA;&lt;h2&gt;Price&lt;/h2&gt;&#xA;&lt;p&gt;As Manfred noted above, the machinery to slow an aircraft is not trivial.  While I'm not familiar of the routine replacement rate for these cables, I would imagine that it would be something else that would have to be monitored.  The cable is actually attached to a large machine which provides the cable with some give.  I can't imagine that they would be cheap, but I'm not familiar with the exact machinery myself.&lt;/p&gt;&#xA;" OwnerUserId="2163" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-04-25T16:02:31.080" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3517" PostTypeId="2" ParentId="3513" CreationDate="2014-04-21T16:40:48.393" Score="14" Body="&lt;p&gt;This is probably due to certification inertia, at least in some part:&lt;br&gt;&#xA;A Piper Archer is certificated with a specific engine type (If you scroll down to &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_Library/rgMakeModel.nsf/0/af90bd3d08b5d26e8625720a0054405a/%24FILE/2A13.pdf&quot;&gt;page 21 of the TCDS&lt;/a&gt; you'll see it's a &quot;Lycoming O-360-A4M&quot;). Piper can essentially make as many Archers as they want under their production certificate as long as they conform the type certificate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing the engine is a major change to the type certificate, and would require more certification test flights, paperwork, and ultimately &lt;em&gt;money&lt;/em&gt; from the manufacturer, and sales would be uncertain (because it would be &lt;em&gt;different&lt;/em&gt; -- A flight school flying 50 planes that are all powered by Lycoming O-360s is not going to want to take on &lt;em&gt;one&lt;/em&gt; turbine-powered plane, it would be a maintenance headache).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It's worth noting that for some portion of the avgas-burning GA fleet efficiency gains similar to (or better than) turboprops can be achieved by converting from old-style Lycoming and Continental engines (which are effectively 1960s engine technology at best) to engines like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rotax_912&quot;&gt;Rotax 912&lt;/a&gt; with modern electronic ignition and engine management systems. An 80HP Rotax would pull a Piper Cub along just as well as an 80HP Continental - The barrier is again in certification (and cost to modify existing aircraft).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On the technical end of things, a turbine engine is overkill for most small GA planes. We're talking about aircraft that usually require 100-300 horsepower (and if we're considering light GA training aircraft you're usually below 200 horsepower). The popular &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot;&gt;PT6 turboprop engine&lt;/a&gt; starts around 500 shaft horsepower and goes up from there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also while a turbine engine is a relatively simple device a &lt;em&gt;turboprop&lt;/em&gt; gets to be pretty complex -- The turbine section is still spinning at turbine speeds, and while this isn't a problem for a jet engine on a turboprop it could easily make the propeller tips reach supersonic speeds (the &quot;Loud and Inefficient&quot; operating range). This necessitates a reduction gearbox to produce an appropriate shaft speed, which in turn necessitates maintenance of the gearbox.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-21T16:40:48.393" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3518" PostTypeId="2" ParentId="3510" CreationDate="2014-04-21T16:53:34.300" Score="2" Body="&lt;p&gt;Some military runways (on land) &lt;em&gt;do&lt;/em&gt; have arresting cables. These are not intended for routine use, but to catch aircraft in danger of running off the end of the runway due to brake failure, touching down too late, etc. Sometimes they may pop-up to snare the undercarriage rather than using a hook, Navy style.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons for not using arresting cables on land have been well discussed above -- airframe and pilot stress from the high G's, maintenance costs, etc. Also, there's usually plenty of land on which to build a runway, so you don't need to stop short as on a carrier.&lt;/p&gt;&#xA;" OwnerUserId="1078" LastActivityDate="2014-04-21T16:53:34.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3519" PostTypeId="1" AcceptedAnswerId="3555" CreationDate="2014-04-21T16:57:51.253" Score="16" ViewCount="23928" Body="&lt;p&gt;Some GA aircraft, notably the DA40/DA42, are equipped with piston engines that use Jet A-1 and/or automotive-grade diesel instead of aviation gas (avgas). An example of such engine is the &lt;a href=&quot;http://austroengine.at/en/products&quot; rel=&quot;noreferrer&quot;&gt;Austro Engine AE300&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/w74Gh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages/disadvantages of these engines and why are they not more common?&lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="2407" LastEditDate="2014-12-17T18:59:09.717" LastActivityDate="2018-06-16T11:37:06.613" Title="What are the advantages/disadvantages of diesel/Jet A-1 piston engine?" Tags="&lt;piston-engine&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3521" PostTypeId="1" AcceptedAnswerId="3527" CreationDate="2014-04-21T17:50:45.300" Score="9" ViewCount="5495" Body="&lt;p&gt;I realize that this is likely to depend on jurisdiction (EASA or FAA would interest me the most in that case), but is there any common-sense kind of line that you don't cross until you've at least checked that it's okay?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean it's obviously okay to put checklists in a side-pocket, and it's obviously not okay to replace the avionics. Can I replace the PTT button on the yoke? Or if I don't touch the wiring and simply add some plastic on top give it a better feel?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="65" LastEditDate="2015-03-04T21:20:43.640" LastActivityDate="2018-05-10T14:03:38.953" Title="What repairs or modifications can be done without approval/certification?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;aircraft-certification&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3522" PostTypeId="2" ParentId="3519" CreationDate="2014-04-21T18:03:20.983" Score="11" Body="&lt;p&gt;Advantage: AvGas is heavily taxed in Europe. This is primarily an envy tax, because it brings in less than the cost of its administration, but the non-flying majority feels good by &quot;punishing the millionaires who waste their money on flying&quot;. AvGas costs currently about 2.6 - 3 € per liter in Germany, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet fuel cannot be taxed in the same way because arbitrage is too easy. Airlines would simply stop refueling within Europe. At prices of around 1 € at large airports the difference is substantial. With a DA-40 you might not get the same price that airlines get, but a sizable difference remains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disadvantage: At pure GA airports, you will have a hard time to get Jet fuel at all. There are very few piston engines which can use Jet A-1 and are rated for aviation. Car engines cannot be used without heavy modifications, because they are not designed for continuous operation at 60% or 70% of their maximum performance. Due to the higher internal pressure, the engines tend to be heavier and produce more vibrations. However, since the specific fuel consumption of a Diesel engine is lower, the total system mass for ranges in excess of 1000 km should be lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GA market is simply too small to support the design of new engines. We have to use what was created half a century ago. It's a shame, but it has been shown several times in the last two decades - there were a number of attempts to create GA diesel engines, with very little to show.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1930's Junkers made a range of very interesting Diesel piston engines (see &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_205&quot;&gt;here&lt;/a&gt;) which powered a range of aircraft designed for very long ranges. They were used for transatlantic mail service (see &lt;a href=&quot;http://en.wikipedia.org/wiki/Do_26&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Blohm_&amp;amp;_Voss_Ha_139&quot;&gt;here&lt;/a&gt; for examples).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-04-23T12:46:00.250" LastActivityDate="2014-04-23T12:46:00.250" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3523" PostTypeId="1" AcceptedAnswerId="3524" CreationDate="2014-04-21T19:53:01.340" Score="21" ViewCount="39604" Body="&lt;p&gt;What are cowl flaps and what are they used for? It seems I have only heard of them in connection with old planes, are they peculiar to radial engines?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="64" LastEditDate="2014-04-22T01:31:44.870" LastActivityDate="2019-01-11T21:01:06.207" Title="What are cowl flaps?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3524" PostTypeId="2" ParentId="3523" CreationDate="2014-04-21T20:13:32.770" Score="31" Body="&lt;p&gt;They are flaps or doors on the engine cowling that open up in order to provide increased cooling airflow for the engine. &lt;a href=&quot;https://i.stack.imgur.com/iblfu.jpg&quot; rel=&quot;noreferrer&quot;&gt;They look like this&lt;/a&gt; when open. They are generally controlled by a handle in the cockpit (some aircraft have electric cowl flaps with an open/close switch).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iblfu.jpg&quot; alt=&quot;open cowl flaps&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disadvantage is that the open flaps also increase drag. So on airplanes equipped with cowl flaps, they are generally opened for low-speed, high-power situations such as takeoff. This is the harshest operational regime for the engine since it is at its highest power and relatively low cooling airflow due to low airspeed. They are then closed either reaching cruise or reaching a point where the airplane can transition to a lower-power, higher-speed climb profile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're not specific to radial engines, but do tend to be more common in older aircraft (there are exceptions though). Newer airplane and engine designs are more likely to have sufficient inherent cooling airflow to not require cowl flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The photo above comes from AVweb, which also has a &lt;a href=&quot;http://www.avweb.com/news/leadingedge/leading_edge_21_remember_your_cowl_flaps_198546-1.html&quot; rel=&quot;noreferrer&quot;&gt;nice article explaining more about the function and usage of cowl flaps&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="8282" LastEditDate="2019-01-11T21:01:06.207" LastActivityDate="2019-01-11T21:01:06.207" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3525" PostTypeId="2" ParentId="3523" CreationDate="2014-04-21T20:13:40.320" Score="9" Body="&lt;p&gt;Cowl flaps are used for engine cooling and you'll find them on many high performance piston aircraft.  They are particularly useful during climbout when you are at a high power setting and slow(ish) airspeed.  Opening the cowl flaps allows more airflow across the engine but produces some drag.  They are typically mounted on the bottom of the engine cowling.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-21T20:13:40.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3526" PostTypeId="2" ParentId="3519" CreationDate="2014-04-21T20:36:14.607" Score="11" Body="&lt;p&gt;Modern aero-diesel engines are far more technically advanced than the majority of avgas powered engines as they are very new designs. Most avgas engines are normally aspirated, most of the time carbureted, and have manually controlled fuel to air mixtures, which is ancient engine technology. Aero-diesels have turbochargers, electronic fuel-injection, and computer-controlled mixture which gives them better performance and efficiency. Prop pitch is also usually computer-controlled, giving the pilot a single-lever control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there are no real disadvantages to the engines themselves, the disadvantages are more around the logistics and start-up costs. There are few mechanics who can work on them, and few aircraft with STCs which allow them to be retrofitted, so if you want one chances are you can't have one. To retrofit (if permitted) requires substantial modifications to fuel tanks, fuel delivery systems, electrical systems, and more, so it's not a cheap option. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-04-21T20:36:14.607" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3527" PostTypeId="2" ParentId="3521" CreationDate="2014-04-21T21:49:13.560" Score="5" Body="&lt;p&gt;This answer applies to FAA certified aircraft.  For experimentals, there are really no restrictions.  I mean, you can build the airplane from scratch so replace what you want...  but for certified aircraft:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following is copied and pasted from the AOPA website:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR Part 43 specifies who may do what to an aircraft in the way of maintenance, repair or alteration. It requires that only properly certified mechanics work on aircraft and &quot;okay&quot; them for return to service. However, it does allow preventive maintenance to be performed by a certificated pilot, holding at least a Private certificate, on an aircraft owned or operated by that pilot, provided the aircraft is not used in commercial service. The responsibilities for a pilot performing preventive maintenance are very similar to those imposed on the certificated mechanic performing other duties. The FARs require that anyone who works on an aircraft must have the appropriate maintenance and service information available. This means quite simply that before you set about performing preventive maintenance items on your airplane, you must first have the proper maintenance manuals available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A list of &quot;preventive maintenance&quot; allowed is specifically listed in FAR 43 appendix A (4) c and is copied below:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Preventive maintenance. Preventive maintenance is limited to the&#xA;  following work, provided it does not involve complex assembly&#xA;  operations:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Removal, installation, and repair of landing gear tires.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Replacing elastic shock absorber cords on landing gear.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Servicing landing gear shock struts by adding oil, air, or both.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Servicing landing gear wheel bearings, such as cleaning and&#xA;  greasing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Replacing defective safety wiring or cotter keys.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) Lubrication not requiring disassembly other than removal of&#xA;  nonstructural items such as cover plates, cowlings, and fairings.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) Making simple fabric patches not requiring rib stitching or the&#xA;  removal of structural parts or control surfaces. In the case of&#xA;  balloons, the making of small fabric repairs to envelopes (as defined&#xA;  in, and in accordance with, the balloon manufacturers' instructions)&#xA;  not requiring load tape repair or replacement.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(8) Replenishing hydraulic fluid in the hydraulic reservoir.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(9) Refinishing decorative coating of fuselage, balloon baskets, wings&#xA;  tail group surfaces (excluding balanced control surfaces), fairings,&#xA;  cowlings, landing gear, cabin, or cockpit interior when removal or&#xA;  disassembly of any primary structure or operating system is not&#xA;  required.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(10) Applying preservative or protective material to components where&#xA;  no disassembly of any primary structure or operating system is&#xA;  involved and where such coating is not prohibited or is not contrary&#xA;  to good practices.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(11) Repairing upholstery and decorative furnishings of the cabin,&#xA;  cockpit, or balloon basket interior when the repairing does not&#xA;  require disassembly of any primary structure or operating system or&#xA;  interfere with an operating system or affect the primary structure of&#xA;  the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(12) Making small simple repairs to fairings, nonstructural cover&#xA;  plates, cowlings, and small patches and reinforcements not changing&#xA;  the contour so as to interfere with proper air flow.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(13) Replacing side windows where that work does not interfere with&#xA;  the structure or any operating system such as controls, electrical&#xA;  equipment, etc.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(14) Replacing safety belts.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(15) Replacing seats or seat parts with replacement parts approved for&#xA;  the aircraft, not involving disassembly of any primary structure or&#xA;  operating system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(16) Trouble shooting and repairing broken circuits in landing light&#xA;  wiring circuits.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(17) Replacing bulbs, reflectors, and lenses of position and landing&#xA;  lights.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(18) Replacing wheels and skis where no weight and balance computation&#xA;  is involved.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(19) Replacing any cowling not requiring removal of the propeller or&#xA;  disconnection of flight controls.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(20) Replacing or cleaning spark plugs and setting of spark plug gap&#xA;  clearance.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(21) Replacing any hose connection except hydraulic connections.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(22) Replacing prefabricated fuel lines.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(23) Cleaning or replacing fuel and oil strainers or filter elements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(24) Replacing and servicing batteries.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(25) Cleaning of balloon burner pilot and main nozzles in accordance&#xA;  with the balloon manufacturer's instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(26) Replacement or adjustment of nonstructural standard fasteners&#xA;  incidental to operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(27) The interchange of balloon baskets and burners on envelopes when&#xA;  the basket or burner is designated as interchangeable in the balloon&#xA;  type certificate data and the baskets and burners are specifically&#xA;  designed for quick removal and installation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(28) The installations of anti-misfueling devices to reduce the&#xA;  diameter of fuel tank filler openings provided the specific device has&#xA;  been made a part of the aircraft type certificate data by the aircraft&#xA;  manufacturer, the aircraft manufacturer has provided FAA-approved&#xA;  instructions for installation of the specific device, and installation&#xA;  does not involve the disassembly of the existing tank filler opening.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(29) Removing, checking, and replacing magnetic chip detectors.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(30) The inspection and maintenance tasks prescribed and specifically&#xA;  identified as preventive maintenance in a primary category aircraft&#xA;  type certificate or supplemental type certificate holder's approved&#xA;  special inspection and preventive maintenance program when&#xA;  accomplished on a primary category aircraft provided:   (i) They are&#xA;  performed by the holder of at least a private pilot certificate issued&#xA;  under part 61 who is the registered owner (including co-owners) of the&#xA;  affected aircraft and who holds a certificate of competency for the&#xA;  affected aircraft (1) issued by a school approved under Sec. 147.21(e)&#xA;  of this chapter; (2) issued by the holder of the production&#xA;  certificate for that primary category aircraft that has a special&#xA;  training program approved under Sec. 21.24 of this subchapter; or (3)&#xA;  issued by another entity that has a course approved by the&#xA;  Administrator; and   (ii) The inspections and maintenance tasks are&#xA;  performed in accordance with instructions contained by the special&#xA;  inspection and preventive maintenance program approved as part of the&#xA;  aircraft's type design or supplemental type design.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(31) Removing and replacing self-contained, front instrument&#xA;  panel-mounted navigation and communication devices that employ&#xA;  tray-mounted connectors that connect the unit when the unit is&#xA;  installed into the instrument panel, (excluding automatic flight&#xA;  control systems, transponders, and microwave frequency distance&#xA;  measuring equipment (DME)). The approved unit must be designed to be&#xA;  readily and repeatedly removed and replaced, and pertinent&#xA;  instructions must be provided. Prior to the unit's intended use, and&#xA;  operational check must be performed in accordance with the applicable&#xA;  sections of part 91 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(32) Updating self-contained, front instrument panel-mounted Air&#xA;  Traffic Control (ATC) navigational software data bases (excluding&#xA;  those of automatic flight control systems, transponders, and microwave&#xA;  frequency distance measuring equipment (DME)) provided no disassembly&#xA;  of the unit is required and pertinent instructions are provided. Prior&#xA;  to the unit's intended use, an operational check must be performed in&#xA;  accordance with applicable sections of part 91 of this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="291" LastEditorUserId="609" LastEditDate="2014-04-21T22:30:32.373" LastActivityDate="2014-04-21T22:30:32.373" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3528" PostTypeId="2" ParentId="3513" CreationDate="2014-04-21T22:57:55.990" Score="20" Body="&lt;p&gt;First, piston engines are &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/rotary-engine-planes-in-commercial-flights/10037#10037&quot;&gt;more efficient than turboprops&lt;/a&gt;, so their operational cost are lower. This also means that the system mass (engine plus fuel) for a trip is lower once you go beyond small ranges. In a helicopter, the engine mass is more important, because average flight times are much shorter, so you find many helicopters with turbo engines and only few with pistons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, there is a well developed infrastructure for maintenance on those pistons, and new turboprops would need new, expensive infrastructure (trained people, tools, spare parts ...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is simply no incentive to develop a new GA engine. The expense to get it certified is too large for the rather small market. This is the same as for Diesel engines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-01T22:43:27.527" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3529" PostTypeId="1" AcceptedAnswerId="3530" CreationDate="2014-04-21T23:01:28.747" Score="15" ViewCount="1946" Body="&lt;p&gt;Are airspace violations (e.g. entry to class B without clearance) based on primary radar and/or Mode C transponder, or something else?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read that Mode C altitude is &lt;a href=&quot;http://www.airsport-corp.com/modec.htm&quot;&gt;based on pressure altitude&lt;/a&gt;, i.e., set to 29.92&quot; ... but presumably that's adjusted at the ATC facility based on the current pressure before being used for altitude enforcement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This begs the question, what would stop one (hypothetically), just winding back the altimeter pressure reading to appear to be at a lower altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to summarize: How are airspace violations detected:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What data input is used? &lt;/li&gt;&#xA;&lt;li&gt;If Mode C reading is used, is it based&#xA;on pilot's altimeter? &lt;/li&gt;&#xA;&lt;li&gt;Would winding back the altimeter make a&#xA;plane report a lower altitude?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="995" LastEditorUserId="19" LastEditDate="2014-04-21T23:39:30.303" LastActivityDate="2015-01-03T02:34:56.893" Title="How are airspace violations detected?" Tags="&lt;airspace&gt;&lt;transponder&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3530" PostTypeId="2" ParentId="3529" CreationDate="2014-04-21T23:13:51.423" Score="13" Body="&lt;p&gt;The transponder usually uses its own pressure reading, not what is set in the pilot's altimeter. So to prevent cheating as you describe, it is inspected and calibrated every 24 months. Tampering with it would be difficult to do on the fly because you'd have to adjust it based on the current atmospheric conditions and what altitude you want to seem to fly at. But yes, you could, in theory, adjust its readings to broadcast something different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I'm aware, only major violations are really pursued, or if ATC knows who you are when you commit the violation.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-21T23:13:51.423" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3531" PostTypeId="2" ParentId="3521" CreationDate="2014-04-21T23:15:41.337" Score="3" Body="&lt;p&gt;My answer below is largely geared toward FAA regulations and US-registered aircraft.&lt;br&gt;&#xA;Other areas may have different governing regulations (e.g. for Europe it's &lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02003R2042-20120801&quot; rel=&quot;nofollow noreferrer&quot;&gt;EC 2042/2003 - Appendix VIII&lt;/a&gt;), but there seem to be some commonly-accepted things pilot-owners may do on their aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broadly, on certificated aircraft pilot-owners are typically permitted to make minor repairs to aircraft they own and operate non-commercially.  For example you can&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Perform an &lt;a href=&quot;https://aviation.stackexchange.com/questions/339/what-should-i-look-for-check-during-an-oil-change&quot;&gt;oil change&lt;/a&gt; (including oil, filter, and cleaning oil screens)&lt;/li&gt;&#xA;&lt;li&gt;Replace burned out nav/position/landing lights&lt;/li&gt;&#xA;&lt;li&gt;Remove / install / replace &lt;em&gt;non-structural&lt;/em&gt; fairings &lt;em&gt;where Weight &amp;amp; Balance changes are not needed&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;Service landing gear (replace shock cords or add oil/air to struts)&lt;/li&gt;&#xA;&lt;li&gt;Clean &amp;amp; regap (or replace) spark plugs &amp;amp; plug leads&lt;/li&gt;&#xA;&lt;li&gt;Service/Replace batteries&lt;/li&gt;&#xA;&lt;li&gt;Change tires (including cleaning and re-packing wheel bearings)&lt;/li&gt;&#xA;&lt;li&gt;Grease/Lubricate the airframe as prescribed by the manufacturer under &quot;preventative maintenance&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;...provided &quot;complex disassembly&quot; is not required to complete the above tasks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also generally accepted that pilots are allowed to add fuel (duh), engine oil (again, duh), water/coolant (for liquid-cooled engines), and to replenish hydraulic fluid in accessible reservoirs that can be serviced without opening the system to air &amp;amp; requiring it to be bled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US FARs actually allow a great deal more than that (&lt;a href=&quot;https://aviation.stackexchange.com/a/3527/64&quot;&gt;see Skip's answer which includes the relevant section of the FARs&lt;/a&gt;), the replacement of certain types of tray-mounted radios, some fabric repair (on fabric-covered aircraft &amp;amp; balloons), and repainting (with the exception of &quot;balanced control surfaces&quot;), however much of that starts getting into the kind of work where special equipment or facilities would be &lt;em&gt;extremely helpful&lt;/em&gt; (if not necessary) to ensure the job is done properly.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are some exceptions to the above (this is by no means an exhaustive list of exceptions):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;EASA regulations are somewhat &lt;em&gt;more&lt;/em&gt; restrictive, see the link above to EC 2042/2003.&lt;/li&gt;&#xA;&lt;li&gt;Canada has an &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/regserv/cars/part5-standards-a507sh-1837.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Owner Maintenance&quot;&lt;/a&gt; category of special airworthiness certificates, which allows much &lt;em&gt;less&lt;/em&gt; restrictive maintenance (but at this time renders the aircraft &quot;unairworthy&quot; for flights in US airspace). (&lt;a href=&quot;http://www.copanational.org/AircraftInCaOwnerMaint.cfm&quot; rel=&quot;nofollow noreferrer&quot;&gt;More info&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;US &quot;Light Sport&quot; certificated aircraft owners are eligible for a &lt;a href=&quot;http://www.sportpilot.org/maintenance/lsa_maintenance_requirements.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;repairman certificate&lt;/a&gt; under FAR 65.107 which lets them perform many tasks that normally require a certificated A&amp;amp;P mechanic, including repairs/maintenance and the required annual &quot;condition inspection&quot;.&lt;/li&gt;&#xA;&lt;li&gt;Experimental Amateur-Built aircraft can be maintained and inspected by the builder-owner (under the assumption that if you're competent enough to &lt;em&gt;build&lt;/em&gt; the thing you're qualified to maintain it).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-04-21T23:15:41.337" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3532" PostTypeId="1" AcceptedAnswerId="3547" CreationDate="2014-04-22T02:06:19.600" Score="8" ViewCount="8887" Body="&lt;p&gt;Does anyone know where to find a list of active NDB approaches? I can find a list of ones proposed to be eliminated, but I'm having a problem coming across a list of remaining ones.&lt;/p&gt;&#xA;" OwnerUserId="2167" LastEditorUserId="69" LastEditDate="2014-04-22T15:50:09.663" LastActivityDate="2014-04-23T18:50:35.940" Title="Where to obtain a list of active NDB approaches?" Tags="&lt;usa&gt;&lt;iaps&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3533" PostTypeId="1" AcceptedAnswerId="3537" CreationDate="2014-04-22T02:30:56.057" Score="8" ViewCount="9507" Body="&lt;p&gt;If I'm selling a plane that has been de-registered, can the new owner re-register the aircraft with the same number (or do they have to get a new one)? Does the airworthiness certificate transfer as well? How long does this process typically take?&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="1696" LastEditDate="2015-02-19T22:16:57.243" LastActivityDate="2015-02-19T22:16:57.243" Title="Can you re-register a de-registered aircraft with the same N-number?" Tags="&lt;faa&gt;&lt;aircraft-registration&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3534" PostTypeId="1" AcceptedAnswerId="3538" CreationDate="2014-04-22T03:21:51.703" Score="5" ViewCount="1303" Body="&lt;p&gt;Old registrations had no expiration date, so a pilot could get in a plane that is owned by someone else and verify the airworthiness and registration by inspecting the documents. But that registration might be expired, and without going to the FAA site to verify it is active could find themselves flying an unregistered aircraft. Has the FAA addressed this situation since they started expiring registrations that didn't originally expire? What would the pilot's liability be in this situation? &lt;/p&gt;&#xA;" OwnerUserId="36" LastEditorUserId="97" LastEditDate="2014-04-22T06:42:04.510" LastActivityDate="2014-04-24T02:49:31.193" Title="What is the pilot's obligation to verify a registration has not expired?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3535" PostTypeId="2" ParentId="3534" CreationDate="2014-04-22T03:44:46.700" Score="3" Body="&lt;p&gt;91.203 and 91.403 make it pretty clear that the owner or operator is primarily responsible for maintaining the aircraft in an airworthy state. If you are flying it, you are the operator and it is up to you to ensure that the plane is registered and airworthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should never get in a plane and fly it without verifying that its maintenance, airworthiness, and registration are up to spec. It's not difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for checking registration itself, simply check if the document is more than 3 years old. If it is, it is most likely expired.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-22T03:44:46.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3536" PostTypeId="2" ParentId="3533" CreationDate="2014-04-22T03:52:18.897" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/reregistration/&quot; rel=&quot;nofollow&quot;&gt;Check the FAA's FAQ here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The N-Number in question cannot be used for 5 years after it expires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airworthiness certificate does not change, it is just invalid without current registration. They may, however, send a new one upon re-registering if the registration expired, if the N-Number changes, or if you request a new certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The process usually takes about a month.&lt;/p&gt;&#xA;" OwnerUserId="277" LastEditorUserId="277" LastEditDate="2014-04-22T04:13:01.310" LastActivityDate="2014-04-22T04:13:01.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3537" PostTypeId="2" ParentId="3533" CreationDate="2014-04-22T04:10:48.210" Score="7" Body="&lt;p&gt;The FAA has &lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/reregistration/&quot;&gt;a page that sort-of takes you through this process&lt;/a&gt;.  Basically it boils down to this:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;If your registration has expired you still have ~90 days to register the aircraft&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a renewal application was first received by the Registry after the expiration date, the renewal process no longer applies. An aircraft owner may apply for registration of an unregistered aircraft under 14 C.F.R. §4731(a), by filing an Aircraft Registration Application, &lt;a href=&quot;https://www.faa.gov/forms/index.cfm/go/document.information/documentID/185220&quot;&gt;AC Form 8050-1&lt;/a&gt;, the $5.00 registration fee, and evidence of ownership (if it is not already on file at the Registry).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's a &quot;new registration&quot;, but you can keep your N number. (Yes, you have to use an official, FAA-Provided 8050-1 form - you can't download them anymore. You're also going to want to talk to someone at the &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/contact_aircraft_certification/&quot;&gt;Aircraft Registration Branch&lt;/a&gt; or your local FSDO before you start filling out forms because you &lt;em&gt;don't&lt;/em&gt; want your form to show up after the 90 day window or you wind up in the &lt;em&gt;other&lt;/em&gt; category...)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;After about 90 days your N number is &lt;em&gt;Cancelled&lt;/em&gt; &amp;amp; unavailable for 5 years&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When an aircraft registration is not renewed, the cancellation of the N-number assigned to that aircraft will take place approximately 90 days after the expiration of an aircraft's registration. Upon cancellation, an N-number will be unavailable for re-assignment or reservation for a period of five years.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;At this point you &lt;em&gt;have&lt;/em&gt; to talk the aircraft registration branch, but my understanding is you are out of luck -- That N number is void and a new number will be issued when you register the aircraft (at which point you must apply the &lt;em&gt;new&lt;/em&gt; N number to the aircraft in accordance with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.22.3&amp;amp;rgn=div6&quot;&gt;FAR 45&lt;/a&gt;, which typically means repainting at least part of the tail).&lt;br&gt;&#xA;You must get a new airworthiness certificate bearing the new registration number from your local FSDO.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In both of these cases &lt;em&gt;your airworthiness certificate is &lt;strong&gt;invalid*&lt;/em&gt;&lt;/strong&gt; (because without a valid registration you have no authority to operate the aircraft).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first case you will not need a replacement airworthiness certificate (because your N number hasn't changed), but if your N number has been cancelled you will  need a new airworthiness certificate issued with the new N number on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total time for all the paperwork to be processed depends on which bucket you fall into -- the aircraft registration branch usually has about a 30-day backlog (&lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/&quot;&gt;check here&lt;/a&gt;), plus time for the post office to move the paper from point A to point B, so a lag of a little over 30 days is what you should expect.&lt;br&gt;&#xA;If a replacement airworthiness certificate is required that will probably add a few days to the process as well.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-22T04:10:48.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3538" PostTypeId="2" ParentId="3534" CreationDate="2014-04-22T04:32:16.943" Score="7" Body="&lt;p&gt;You verify new (expiring) registrations the same way you verified the old (&amp;quot;for life&amp;quot;) registrations -- &lt;em&gt;by looking at the document&lt;/em&gt;. You just have to pay attention now (it's not just &amp;quot;It's there&amp;quot;, you need to check the expiration date too).&lt;/p&gt;&#xA;&lt;p&gt;New-style registration certificates (issued some time after October 2010) are supposed to have the expiration date clearly printed on the certificate (&lt;a href=&quot;https://i.stack.imgur.com/zfOYO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;In the lower-left corner, under the date of issue&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;For certificates without an expiration date printed on them (registered prior to October 2010) the FAA established a table of expiration dates back when the re-registration requirement was initiated.&lt;br /&gt;&#xA;&lt;em&gt;&lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=11617&quot; rel=&quot;nofollow noreferrer&quot;&gt;ALL of the old certificates have expired by now: The last ones expired December 31, 2013&lt;/a&gt;.&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As regards the pilot's liability, an unregistered aircraft (or one with an expired airworthiness certificate) is &lt;em&gt;de facto&lt;/em&gt; unairworthy:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;Does expiration of registration affect an aircraft's airworthiness certificate?&lt;/h3&gt;&#xA;&lt;p&gt;Because an aircraft with an expired registration is not registered, its airworthiness certification would be considered ineffective. Without registration the aircraft is not authorized for flight.&lt;br /&gt;&#xA;…&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/reregistration_faq/&quot; rel=&quot;nofollow noreferrer&quot;&gt;The FAA's registration FAQ&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Aside from being a violation of the FARs to fly the aircraft with an expired registration (because it's &amp;quot;not airworthy&amp;quot;) this triggers other implications, for example most aircraft insurance is invalid if the aircraft is &amp;quot;not airworthy&amp;quot; .&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-24T02:49:31.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3539" PostTypeId="1" AcceptedAnswerId="3540" CreationDate="2014-04-22T09:10:00.180" Score="20" ViewCount="2108" Body="&lt;p&gt;I've often noticed that planes flying on more or less the same track, headed in the same direction leaves different contrails. By different I mean how long they stay visible and the length of them. Why is this so? Is it weather related?&lt;/p&gt;&#xA;" OwnerUserId="1815" LastActivityDate="2014-04-22T12:28:32.283" Title="Why are some contrails longer than others?" Tags="&lt;weather&gt;&lt;contrails&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3540" PostTypeId="2" ParentId="3539" CreationDate="2014-04-22T10:12:40.057" Score="24" Body="&lt;p&gt;It is a mixture of factors. All else being the same:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;a contrail at a higher altitude will last longer (the lower temperature slows the sublimation of the ice cristals)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;a contrail formed in air with higher humidity will be bigger and last longer (more water is being turned into ice)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If there is not enough (relative) humidity, the contrail will not form at all. See for example this image:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/okj64.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sup&gt;&lt;em&gt;Image from &lt;a href=&quot;http://visibleearth.nasa.gov/view.php?id=55122&quot; rel=&quot;noreferrer&quot;&gt;NASA&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The contrails start forming on the east, near the clouds where you have a higher humidity, and do not form on the west, where no cloud is present and you have higher temperature/lower humidity.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I've often noticed that planes flying on more or less the same track, headed in the same direction leaves different contrails. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What you observe might be airplanes flying at different altitudes and thus encountering different humidity/temperature combinations, giving birth to contrails with different histories.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-04-22T12:28:32.283" LastActivityDate="2014-04-22T12:28:32.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3541" PostTypeId="1" AcceptedAnswerId="3546" CreationDate="2014-04-22T12:35:03.573" Score="36" ViewCount="5839" Body="&lt;p&gt;While most travelers are well familiar with the security measures imposed by conventional airlines, it is unclear how they apply to private aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible for a private individual to charter a 747 for private uses? And if so, are there any security measures in place to prevent said private individual from misusing the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(hopefully this question won't get me on the no-fly list) :)&lt;/p&gt;&#xA;" OwnerUserId="2172" LastEditorUserId="97" LastEditDate="2014-04-23T23:33:55.357" LastActivityDate="2014-04-23T23:33:55.357" Title="What are the security measures preventing someone from chartering a 747 and using it to commit a terrorist attack?" Tags="&lt;security&gt;&lt;terrorism&gt;&lt;tsa&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3542" PostTypeId="2" ParentId="3513" CreationDate="2014-04-22T12:40:20.237" Score="8" Body="&lt;p&gt;First, for a given power rating, a turbine engine will be a lot lighter than a piston engine. Think about what that does to the aircraft's balance: the nose gets a LOT longer, not to accommodate the hardware put to put the weight where it needs to be. Of course, this only applies to conversions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, a turbine engine will cost a lot more than a piston engine. Smaller turbines cost more per unit of power than large ones, so overall you will be paying more for the same result. The engine &lt;em&gt;might&lt;/em&gt; use less fuel over it's lifetime but you still have to pay for it up front.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, while turbines in general require less maintenance, when something does have a problem the bill is not for the fainthearted. And you can cook a turbine pretty easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in total it just comes down to money. If you really want one, Soloy sells a conversion kit for a Cessna 206 that will put a 450hp Rolls-Royce turbine in the nose and make you the envy of every other light aircraft owner in the region. The kit starts at $275,000. Plus engine. So you are looking at over half a million to modify an airframe that costs a bit less than that. If you have that much spare cash, pick up a matching MTT Superbike with an only slightly smaller turbine. As Jay Leno said, it's &quot;the best ever motorcycle for shutting up the Harley guys.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-04-22T12:40:20.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3543" PostTypeId="2" ParentId="3541" CreationDate="2014-04-22T13:15:28.357" Score="43" Body="&lt;p&gt;I haven't spoken to any terrorists, so the only source I have for this is Bruce Schneier, but apparently, they're &lt;strong&gt;hard&lt;/strong&gt; to pull off. Objectively, this makes sense; if they were easy, there would be more of them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of not referencing any actual living or dead person, let's call our supposed terrorist &quot;Hans Gruber&quot;. Hans has enough money to charter a 747 and the desire to terrorize someone. How does he go about it?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If he charters the plane himself, takes control of it, and then crashes it into something (the Nakatomi tower, perhaps), and succeeds, then he dies. Surprisingly, I don't know of many people who are (a) willing to commit terror, (b) willing to &lt;em&gt;personally&lt;/em&gt; die for their cause, and (c) multimillionaires.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Okay, what if Hans puts up the money but hires someone else to fly?  Well, money comes from somewhere and charter operators tend to remember you when your passenger hijacks and crashes your 747. Suddenly now you have the authorities after you. Plus, there's no guarantee that the person you hired is going to get the job done. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Okay, but what if Hans is the president of a group of shell companies that can funnel money here and there and disguise the source? Sorry, no good there either. The more people who know about your plan, the more likely the NSA knows about it. At some point (and I would guess that point is not very large) more people in the know results in diminishing returns.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Okay, but what about an opponent who has lots of money, enough willing people to pull off the plan, resources to get them in place and provide the proper training, all while disguising the source? A &lt;em&gt;vast conspiracy&lt;/em&gt;? Well, yes, those exist. They're called nations, and other nations go to war with them over things like that. But at that point, it's not really terrorism anymore, is it?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-04-22T13:15:28.357" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="3545" PostTypeId="2" ParentId="225" CreationDate="2014-04-22T14:27:35.747" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://worldaerodata.com/&quot; rel=&quot;nofollow&quot;&gt;World Aero Data&lt;/a&gt; shows airports on a map, although I did find an &lt;a href=&quot;http://en.wikipedia.org/wiki/Bay_Bridge_Airport&quot; rel=&quot;nofollow&quot;&gt;airport&lt;/a&gt; which isn't mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than that, the map and airports are easily visible, irrespective of zoom level.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-04-22T14:27:35.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3546" PostTypeId="2" ParentId="3541" CreationDate="2014-04-22T17:37:08.810" Score="39" Body="&lt;p&gt;Yes!  You can charter large aircraft like the 747.  A lot of airlines offer this service for large groups (sports teams come to mind), and there are also operators of the Boeing Business Jet that were created just for private and charter uses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TSA requires aircraft like this to adopt a security program called the Twelve-Five Standard Security Program (or TFSSP for short).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=09058d33263a3e3444c6cde4f3b25e8f&amp;amp;node=49:9.1.3.5.11&amp;amp;rgn=div5&quot;&gt;49 CFR Part 1544&lt;/a&gt; contains the regulations which cover this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the security program falls under non-disclosure rules that prevent anyone with knowledge of the program from talking about it to people that don't have an operational need to know (and have also signed a non-disclosure).  This helps to prevent people that would try to bypass the security measures in place from even knowing what to look for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulations do specify the following though:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Each operator of an aircraft that weighs more than 12,500 lbs. that is used for scheduled or charter operations must adopt the program.&lt;/li&gt;&#xA;&lt;li&gt;The program must be approved by the TSA.&lt;/li&gt;&#xA;&lt;li&gt;The program must contain the procedures and description of the facilities and equipment used regarding:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the acceptance and screening of individuals and their accessible property, including, if applicable, the carriage weapons as part of State-required emergency equipment,&lt;/li&gt;&#xA;&lt;li&gt;the acceptance and screening of checked baggage,&lt;/li&gt;&#xA;&lt;li&gt;the acceptance and screening of cargo,&lt;/li&gt;&#xA;&lt;li&gt;the screening of individuals and property,&lt;/li&gt;&#xA;&lt;li&gt;the use of metal detection devices,&lt;/li&gt;&#xA;&lt;li&gt;regarding the use of x-ray systems,&lt;/li&gt;&#xA;&lt;li&gt;the use of explosives detection systems,&lt;/li&gt;&#xA;&lt;li&gt;the responsibilities of security coordinators,&lt;/li&gt;&#xA;&lt;li&gt;the requirements for law enforcement personnel,&lt;/li&gt;&#xA;&lt;li&gt;carriage of accessible weapons,&lt;/li&gt;&#xA;&lt;li&gt;carriage of prisoners under the control of armed law enforcement officers,&lt;/li&gt;&#xA;&lt;li&gt;transportation of Federal Air Marshals,&lt;/li&gt;&#xA;&lt;li&gt;aircraft and facilities control function,&lt;/li&gt;&#xA;&lt;li&gt;the specific locations where the air carrier has entered into an exclusive area agreement,&lt;/li&gt;&#xA;&lt;li&gt;fingerprint-based criminal history records checks,&lt;/li&gt;&#xA;&lt;li&gt;personnel identification systems,&lt;/li&gt;&#xA;&lt;li&gt;training,&lt;/li&gt;&#xA;&lt;li&gt;an aviation security contingency plan,&lt;/li&gt;&#xA;&lt;li&gt;bomb and air piracy threats,&lt;/li&gt;&#xA;&lt;li&gt;flight deck privileges, and&lt;/li&gt;&#xA;&lt;li&gt;the Aircraft Operator Implementation Plan (AOIP).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As you can see, there is quite a bit that goes into the TFSSP.  Two of the biggest things though are the requirement for all flight crew members to undergo a fingerprint based criminal background check and that access to the flight deck must be restricted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more details, refer to the actual regulations which cover this in more depth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nbaa.org/ops/security/programs/tfssp/&quot;&gt;NBAA&lt;/a&gt; also has a page about the TFSSP.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-22T17:49:47.933" LastActivityDate="2014-04-22T17:49:47.933" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3547" PostTypeId="2" ParentId="3532" CreationDate="2014-04-22T19:32:02.467" Score="7" Body="&lt;p&gt;This list comes from a database query against an ARINC 424 navigation database. The data is &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/digitalproducts/nfd/&quot; rel=&quot;noreferrer&quot;&gt;available on a subscription basis (for a fee) from the FAA&lt;/a&gt; as a raw, computer-readable data file, but it is not human readable, and querying it requires special software not accessible to the typical interested party. I have done the query for you and pasted the results.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the database doesn't distinguish between &quot;NDB RWY XX&quot; and &quot;NDB OR GPS RWY XX&quot; so the titles here may not precisely match what you see on the plate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time permitting I'll see if I can update the list (and note any changes) using the most up-to-date navigation database. This list is based on an expired (by 2 months or so) database. These approaches are dropping like flies.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;02A  NDB RWY 26  (CLANTON, AL)&#xA;06FA NDB RWY 09  (JUPITER, FL)&#xA;06FA NDB RWY 27  (JUPITER, FL)&#xA;0F2  NDB RWY 17  (BOWIE, TX)&#xA;0F2  NDB RWY 35  (BOWIE, TX)&#xA;0M3  NDB RWY 02  (HOHENWALD, TN)&#xA;15F  NDB RWY 18  (HASKELL, TX)&#xA;16G  NDB RWY 24  (TIFFIN, OH)&#xA;1B1  NDB-A       (HUDSON, NY)&#xA;1B9  NDB RWY 32  (MANSFIELD, MA)&#xA;1G3  NDB RWY 01  (KENT, OH)&#xA;1H8  NDB RWY 04  (CASEY, IL)&#xA;1H8  NDB RWY 22  (CASEY, IL)&#xA;1J0  NDB-A       (BONIFAY, FL)&#xA;1S3  NDB RWY 26  (FORSYTH, MT)&#xA;21D  NDB RWY 04  (ST PAUL, MN)&#xA;23R  NDB RWY 35  (DEVINE, TX)&#xA;28J  NDB RWY 09  (PALATKA, FL)&#xA;2A0  NDB RWY 03  (DAYTON, TN)&#xA;2B7  NDB RWY 36  (PITTSFIELD, ME)&#xA;2F5  NDB RWY 16  (LAMESA, TX)&#xA;2F5  NDB RWY 34  (LAMESA, TX)&#xA;2G9  NDB RWY 25  (SOMERSET, PA)&#xA;2H0  NDB-A       (SHELBYVILLE, IL)&#xA;2J5  NDB RWY 17  (MILLEN, GA)&#xA;2M2  NDB RWY 17  (LAWRENCEBURG, TN)&#xA;2R6  NDB RWY 36  (BUNKIE, LA)&#xA;35A  NDB RWY 05  (UNION, SC)&#xA;3B4  NDB-B       (ELIOT, ME)&#xA;3F3  NDB RWY 18  (MANSFIELD, LA)&#xA;3F4  NDB RWY 09  (VIVIAN, LA)&#xA;3JC  NDB-B       (JUNCTION CITY, KS)&#xA;45R  NDB RWY 13  (KOUNTZE/SILSBEE, TX)&#xA;48Y  NDB RWY 33  (PINECREEK, MN)&#xA;4A9  NDB-A       (FT PAYNE, AL)&#xA;4F2  NDB RWY 35  (CARTHAGE, TX)&#xA;4K6  NDB RWY 36  (BLOOMFIELD, IA)&#xA;4R7  NDB RWY 16  (EUNICE, LA)&#xA;4V8  NDB RWY 01  (WEST DOVER, VT)&#xA;53A  NDB RWY 18  (MONTEZUMA, GA)&#xA;5R4  NDB RWY 18  (FOLEY, AL)&#xA;5R8  NDB RWY 16  (DE QUINCY, LA)&#xA;6B6  NDB-A       (STOW, MA)&#xA;70J  NDB RWY 13  (CAIRO, GA)&#xA;79J  NDB RWY 29  (ANDALUSIA/OPP, AL)&#xA;79J  NDB-A       (ANDALUSIA/OPP, AL)&#xA;7F3  NDB RWY 35  (CADDO MILLS, TX)&#xA;8A0  NDB-A       (ALBERTVILLE, AL)&#xA;8B0  NDB-A       (RANGELEY, ME)&#xA;8F3  NDB RWY 35  (CROSBYTON, TX)&#xA;8G2  NDB RWY 14  (CORRY, PA)&#xA;D73  NDB-A       (MONROE, GA)&#xA;E30  NDB RWY 35  (BALLINGER, TX)&#xA;E38  NDB RWY 19  (ALPINE, TX)&#xA;F10  NDB RWY 36  (HENRYETTA, OK)&#xA;F17  NDB RWY 17  (CENTER, TX)&#xA;F44  NDB RWY 35  (ATHENS, TX)&#xA;F46  NDB-A       (ROCKWALL, TX)&#xA;F99  NDB RWY 17  (HOLDENVILLE, OK)&#xA;I23  NDB RWY 23  (WASHINGTON COURT HOUSE, OH)&#xA;I68  NDB-A       (LEBANON, OH)&#xA;I69  NDB RWY 22  (BATAVIA, OH)&#xA;K34  NDB-D       (GARDNER, KS)&#xA;K88  NDB RWY 01  (IOLA, KS)&#xA;KAAA NDB RWY 21  (LINCOLN, IL)&#xA;KAAF NDB RWY 14  (APALACHICOLA, FL)&#xA;KAAF NDB RWY 32  (APALACHICOLA, FL)&#xA;KAAS NDB RWY 23  (CAMPBELLSVILLE, KY)&#xA;KABI NDB RWY 35R (ABILENE, TX)&#xA;KABR NDB RWY 31  (ABERDEEN, SD)&#xA;KABY NDB RWY 04  (ALBANY, GA)&#xA;KACK NDB RWY 24  (NANTUCKET, MA)&#xA;KACP NDB RWY 36  (OAKDALE, LA)&#xA;KADF NDB RWY 04  (ARKADELPHIA, AR)&#xA;KADG NDB RWY 05  (ADRIAN, MI)&#xA;KAFK NDB RWY 15  (NEBRASKA CITY, NE)&#xA;KAFK NDB RWY 33  (NEBRASKA CITY, NE)&#xA;KAHN NDB RWY 27  (ATHENS, GA)&#xA;KAHQ NDB RWY 20  (WAHOO, NE)&#xA;KAID NDB RWY 30  (ANDERSON, IN)&#xA;KAIK NDB RWY 25  (AIKEN, SC)&#xA;KAIT NDB RWY 16  (AITKIN, MN)&#xA;KAJR NDB RWY 06  (CORNELIA, GA)&#xA;KAKH NDB RWY 03  (GASTONIA, NC)&#xA;KAKQ NDB RWY 20  (WAKEFIELD, VA)&#xA;KAKR NDB RWY 25  (AKRON, OH)&#xA;KALN NDB RWY 17  (ALTON-ST LOUIS, IL)&#xA;KALW NDB RWY 20  (WALLA WALLA, WA)&#xA;KALX NDB-A       (ALEXANDER CITY, AL)&#xA;KAMA NDB RWY 04  (AMARILLO, TX)&#xA;KAMT NDB RWY 23  (WEST UNION, OH)&#xA;KANB NDB RWY 05  (ANNISTON, AL)&#xA;KANQ NDB RWY 05  (ANGOLA, IN)&#xA;KAPG NDB RWY 22  (ABERDEEN PROVING GROUNDS, MD)&#xA;KAPN NDB RWY 01  (ALPENA, MI)&#xA;KAPT NDB RWY 04  (JASPER, TN)&#xA;KAQP NDB RWY 13  (APPLETON, MN)&#xA;KARM NDB RWY 14  (WHARTON, TX)&#xA;KARM NDB RWY 32  (WHARTON, TX)&#xA;KARV NDB RWY 28  (MINOCQUA-WOODRUFF, WI)&#xA;KASH NDB RWY 14  (NASHUA, NH)&#xA;KATA NDB RWY 05  (ATLANTA, TX)&#xA;KATS NDB RWY 12  (ARTESIA, NM)&#xA;KATS NDB RWY 30  (ARTESIA, NM)&#xA;KATY NDB RWY 35  (WATERTOWN, SD)&#xA;KAVQ NDB RWY 12  (MARANA, AZ)&#xA;KAWG NDB RWY 31  (WASHINGTON, IA)&#xA;KAWO NDB RWY 34  (ARLINGTON, WA)&#xA;KAXA NDB RWY 12  (ALGONA, IA)&#xA;KAZC NDB-A       (COLORADO CITY, AZ)&#xA;KAZE NDB RWY 14  (HAZLEHURST, GA)&#xA;KAZO NDB RWY 35  (KALAMAZOO, MI)&#xA;KBBB NDB RWY 14  (BENSON, MN)&#xA;KBBD NDB RWY 17  (BRADY, TX)&#xA;KBBP NDB RWY 07  (BENNETTSVILLE, SC)&#xA;KBCB NDB-A       (BLACKSBURG, VA)&#xA;KBED NDB RWY 29  (BEDFORD, MA)&#xA;KBEH NDB RWY 28  (BENTON HARBOR, MI)&#xA;KBFK NDB-A       (BUFFALO, OK)&#xA;KBFW NDB RWY 25  (SILVER BAY, MN)&#xA;KBGF NDB RWY 18  (WINCHESTER, TN)&#xA;KBHC NDB RWY 08  (BAXLEY, GA)&#xA;KBHK NDB RWY 13  (BAKER, MT)&#xA;KBHK NDB RWY 31  (BAKER, MT)&#xA;KBIL NDB RWY 10L (BILLINGS, MT)&#xA;KBKS NDB RWY 35  (FALFURRIAS, TX)&#xA;KBKT NDB-A       (BLACKSTONE, VA)&#xA;KBMC NDB-A       (BRIGHAM CITY, UT)&#xA;KBOI NDB RWY 10R (BOISE, ID)&#xA;KBPP NDB RWY 29  (BOWMAN, ND)&#xA;KBQP NDB RWY 34  (BASTROP, LA)&#xA;KBRD NDB RWY 23  (BRAINERD, MN)&#xA;KBST NDB RWY 15  (BELFAST, ME)&#xA;KBTL NDB RWY 23R (BATTLE CREEK, MI)&#xA;KBTR NDB RWY 31  (BATON ROUGE, LA)&#xA;KBUB NDB RWY 15  (BURWELL, NE)&#xA;KBVS NDB RWY 11  (BURLINGTON/MT VERNON, WA)&#xA;KBWG NDB RWY 03  (BOWLING GREEN, KY)&#xA;KCAV NDB RWY 14  (CLARION, IA)&#xA;KCBG NDB RWY 34  (CAMBRIDGE, MN)&#xA;KCBK NDB RWY 17  (COLBY, KS)&#xA;KCCY NDB RWY 12  (CHARLES CITY, IA)&#xA;KCDA NDB RWY 02  (LYNDONVILLE, VT)&#xA;KCDR NDB RWY 20  (CHADRON, NE)&#xA;KCEU NDB RWY 25  (CLEMSON, SC)&#xA;KCFJ NDB RWY 04  (CRAWFORDSVILLE, IN)&#xA;KCFV NDB RWY 35  (COFFEYVILLE, KS)&#xA;KCGE NDB RWY 34  (CAMBRIDGE, MD)&#xA;KCHD NDB RWY 04R (CHANDLER, AZ)&#xA;KCHQ NDB RWY 36  (CHARLESTON, MO)&#xA;KCII NDB RWY 23  (CHOTEAU, MT)&#xA;KCIR NDB RWY 14  (CAIRO, IL)&#xA;KCIU NDB RWY 34  (SAULT STE MARIE, MI)&#xA;KCJR NDB RWY 04  (CULPEPER, VA)&#xA;KCKC NDB RWY 27  (GRAND MARAIS, MN)&#xA;KCKF NDB RWY 10  (CORDELE, GA)&#xA;KCKI NDB RWY 14  (KINGSTREE, SC)&#xA;KCKN NDB RWY 13  (CROOKSTON, MN)&#xA;KCMI NDB RWY 32R (CHAMPAIGN-URBANA, IL)&#xA;KCMY NDB RWY 29  (SPARTA, WI)&#xA;KCNH NDB-A       (CLAREMONT, NH)&#xA;KCNI NDB RWY 05  (CANTON, GA)&#xA;KCNK NDB-A       (CONCORDIA, KS)&#xA;KCNP NDB RWY 30  (CHAPPELL, NE)&#xA;KCNW NDB RWY 35R (WACO, TX)&#xA;KCOE NDB RWY 06  (COEUR D'ALENE, ID)&#xA;KCOQ NDB RWY 17  (CLOQUET, MN)&#xA;KCOQ NDB RWY 35  (CLOQUET, MN)&#xA;KCOS NDB RWY 35L (COLORADO SPRINGS, CO)&#xA;KCPC NDB RWY 06  (WHITEVILLE, NC)&#xA;KCQB NDB RWY 35  (CHANDLER, OK)&#xA;KCQX NDB-A       (CHATHAM, MA)&#xA;KCRS NDB RWY 14  (CORSICANA, TX)&#xA;KCRS NDB RWY 32  (CORSICANA, TX)&#xA;KCSB NDB RWY 14  (CAMBRIDGE, NE)&#xA;KCSB NDB RWY 32  (CAMBRIDGE, NE)&#xA;KCSQ NDB RWY 34  (CRESTON, IA)&#xA;KCUH NDB RWY 36  (CUSHING, OK)&#xA;KCVC NDB RWY 28  (ATLANTA, GA)&#xA;KCVO NDB RWY 17  (CORVALLIS, OR)&#xA;KCVX NDB RWY 09  (CHARLEVOIX, MI)&#xA;KCVX NDB RWY 27  (CHARLEVOIX, MI)&#xA;KCWC NDB RWY 35  (WICHITA FALLS, TX)&#xA;KCWS NDB-A       (CONWAY, AR)&#xA;KCWV NDB RWY 09  (CLAXTON, GA)&#xA;KCXO NDB RWY 14  (HOUSTON, TX)&#xA;KCXU NDB RWY 08  (CAMILLA, GA)&#xA;KCYS NDB RWY 27  (CHEYENNE, WY)&#xA;KCYW NDB RWY 35  (CLAY CENTER, KS)&#xA;KCZT NDB RWY 31  (CARRIZO SPRINGS, TX)&#xA;KDAA NDB RWY 32  (FT BELVOIR, VA)&#xA;KDAW NDB RWY 33  (ROCHESTER, NH)&#xA;KDAW NDB-B       (ROCHESTER, NH)&#xA;KDAY NDB RWY 06R (DAYTON, OH)&#xA;KDCM NDB RWY 35  (CHESTER, SC)&#xA;KDET NDB RWY 15  (DETROIT, MI)&#xA;KDEW NDB-A       (DEER PARK, WA)&#xA;KDLC NDB RWY 07  (DILLON, SC)&#xA;KDLZ NDB RWY 10  (DELAWARE, OH)&#xA;KDMO NDB RWY 18  (SEDALIA, MO)&#xA;KDMO NDB RWY 36  (SEDALIA, MO)&#xA;KDNL NDB RWY 11  (AUGUSTA, GA)&#xA;KDNL NDB RWY DMC (AUGUSTA, GA)&#xA;KDNS NDB RWY 30  (DENISON, IA)&#xA;KDRI NDB RWY 36  (DE RIDDER, LA)&#xA;KDRT NDB RWY 13  (DEL RIO, TX)&#xA;KDTO NDB RWY 18  (DENTON, TX)&#xA;KDVK NDB-A       (DANVILLE, KY)&#xA;KDXX NDB RWY 32  (MADISON, MN)&#xA;KDYB NDB RWY 06  (SUMMERVILLE, SC)&#xA;KEAR NDB RWY 36  (KEARNEY, NE)&#xA;KEAU NDB RWY 22  (EAU CLAIRE, WI)&#xA;KEBS NDB RWY 32  (WEBSTER CITY, IA)&#xA;KECG NDB RWY 10  (ELIZABETH CITY, NC)&#xA;KEFW NDB RWY 32  (JEFFERSON, IA)&#xA;KEGQ NDB RWY 13  (EMMETSBURG, IA)&#xA;KEGQ NDB RWY 31  (EMMETSBURG, IA)&#xA;KEGT NDB RWY 35  (WELLINGTON, KS)&#xA;KEHA NDB RWY 35  (ELKHART, KS)&#xA;KEHO NDB RWY 23  (SHELBY, NC)&#xA;KEMT NDB-C       (EL MONTE, CA)&#xA;KEOE NDB RWY 22  (NEWBERRY, SC)&#xA;KEOK NDB RWY 14  (KEOKUK, IA)&#xA;KEOK NDB RWY 26  (KEOKUK, IA)&#xA;KEOP NDB RWY 25  (WAVERLY, OH)&#xA;KEPM NDB RWY 15  (EASTPORT, ME)&#xA;KEPM NDB RWY 33  (EASTPORT, ME)&#xA;KERI NDB RWY 06  (ERIE, PA)&#xA;KERI NDB RWY 24  (ERIE, PA)&#xA;KERV NDB RWY 30  (KERRVILLE, TX)&#xA;KETC NDB RWY 27  (TARBORO, NC)&#xA;KETN NDB RWY 35  (EASTLAND, TX)&#xA;KEUL NDB RWY 30  (CALDWELL, ID)&#xA;KEVB NDB RWY 29  (NEW SMYRNA BEACH, FL)&#xA;KEVV NDB RWY 22  (EVANSVILLE, IN)&#xA;KEVY NDB-A       (MIDDLETOWN, DE)&#xA;KEWB NDB RWY 05  (NEW BEDFORD, MA)&#xA;KEWK NDB RWY 35  (NEWTON, KS)&#xA;KEYE NDB RWY 21  (INDIANAPOLIS, IN)&#xA;KEYW NDB-A       (KEY WEST, FL)&#xA;KEZF NDB RWY 24  (FREDERICKSBURG, VA)&#xA;KEZM NDB RWY 02  (EASTMAN, GA)&#xA;KEZZ NDB RWY 35  (CAMERON, MO)&#xA;KFAF NDB RWY 14  (FT EUSTIS, VA)&#xA;KFBG NDB RWY 27  (FT BRAGG, NC)&#xA;KFBY NDB-A       (FAIRBURY, NE)&#xA;KFCH NDB-B       (FRESNO, CA)&#xA;KFDW NDB RWY 04  (WINNSBORO, SC)&#xA;KFES NDB RWY 36  (FESTUS, MO)&#xA;KFFC NDB RWY 31  (ATLANTA, GA)&#xA;KFFL NDB RWY 36  (FAIRFIELD, IA)&#xA;KFFM NDB RWY 31  (FERGUS FALLS, MN)&#xA;KFHR NDB RWY 34  (FRIDAY HARBOR, WA)&#xA;KFHU NDB RWY 26  (FT HUACHUCA, AZ)&#xA;KFIT NDB RWY 20  (FITCHBURG, MA)&#xA;KFIT NDB-A       (FITCHBURG, MA)&#xA;KFKR NDB RWY 09  (FRANKFORT, IN)&#xA;KFLV NDB RWY 34  (FT LEAVENWORTH, KS)&#xA;KFMH NDB RWY 23  (FALMOUTH, MA)&#xA;KFMZ NDB RWY 17  (FAIRMONT, NE)&#xA;KFMZ NDB RWY 35  (FAIRMONT, NE)&#xA;KFNB NDB-A       (FALLS CITY, NE)&#xA;KFOE NDB RWY 13  (TOPEKA, KS)&#xA;KFOZ NDB RWY 15  (BIGFORK, MN)&#xA;KFPR NDB RWY 28L (FT PIERCE, FL)&#xA;KFPR NDB-A       (FT PIERCE, FL)&#xA;KFRG NDB RWY 01  (FARMINGDALE, NY)&#xA;KFRI NDB RWY 04  (FT RILEY, KS)&#xA;KFSE NDB RWY 34  (FOSSTON, MN)&#xA;KFSI NDB RWY 17  (FT SILL, OK)&#xA;KFSI NDB-A       (FT SILL, OK)&#xA;KFSK NDB RWY 18  (FT SCOTT, KS)&#xA;KFSM NDB RWY 25  (FT SMITH, AR)&#xA;KFTG NDB RWY 26  (DENVER, CO)&#xA;KFTK NDB RWY 18  (FT KNOX, KY)&#xA;KFTY NDB RWY 08  (ATLANTA, GA)&#xA;KFVX NDB RWY 03  (FARMVILLE, VA)&#xA;KFWC NDB RWY 09  (FAIRFIELD, IL)&#xA;KFXY NDB RWY 33  (FOREST CITY, IA)&#xA;KFYE NDB RWY 19  (SOMERVILLE, TN)&#xA;KFYM NDB RWY 20  (FAYETTEVILLE, TN)&#xA;KFZG NDB RWY 01  (FITZGERALD, GA)&#xA;KFZI NDB RWY 27  (FOSTORIA, OH)&#xA;KGAI NDB RWY 14  (GAITHERSBURG, MD)&#xA;KGBD NDB RWY 35  (GREAT BEND, KS)&#xA;KGBR NDB-A       (GREAT BARRINGTON, MA)&#xA;KGCK NDB RWY 35  (GARDEN CITY, KS)&#xA;KGCY NDB RWY 05  (GREENEVILLE, TN)&#xA;KGDV NDB RWY 12  (GLENDIVE, MT)&#xA;KGEY NDB RWY 34  (GREYBULL, WY)&#xA;KGGE NDB RWY 05  (GEORGETOWN, SC)&#xA;KGGF NDB RWY 15  (GRANT, NE)&#xA;KGGF NDB RWY 33  (GRANT, NE)&#xA;KGGG NDB RWY 13  (LONGVIEW, TX)&#xA;KGGW NDB RWY 30  (GLASGOW, MT)&#xA;KGHG NDB RWY 06  (MARSHFIELD, MA)&#xA;KGHG NDB RWY 24  (MARSHFIELD, MA)&#xA;KGLR NDB RWY 09  (GAYLORD, MI)&#xA;KGLY NDB RWY 04  (CLINTON, MO)&#xA;KGLY NDB RWY 22  (CLINTON, MO)&#xA;KGMU NDB RWY 01  (GREENVILLE, SC)&#xA;KGNC NDB RWY 35  (SEMINOLE, TX)&#xA;KGNF NDB RWY 13  (GRENADA, MS)&#xA;KGNG NDB RWY 25  (GOODING, ID)&#xA;KGOV NDB RWY 14  (GRAYLING, MI)&#xA;KGRD NDB RWY 27  (GREENWOOD, SC)&#xA;KGRF NDB RWY 15  (FT LEWIS, WA)&#xA;KGRF NDB RWY 33  (FT LEWIS, WA)&#xA;KGRK NDB RWY 15  (FT HOOD, TX)&#xA;KGRN NDB RWY 22  (GORDON, NE)&#xA;KGSO NDB RWY 14  (GREENSBORO, NC)&#xA;KGTB NDB RWY 15  (FT DRUM, NY)&#xA;KGTB NDB RWY 33  (FT DRUM, NY)&#xA;KGTF NDB RWY 34  (GREAT FALLS, MT)&#xA;KGUR NDB RWY 32  (GUERNSEY, WY)&#xA;KGUY NDB RWY 18  (GUYMON, OK)&#xA;KGVL NDB RWY 05  (GAINESVILLE, GA)&#xA;KGWR NDB RWY 34  (GWINNER, ND)&#xA;KGXY NDB RWY 34  (GREELEY, CO)&#xA;KGYH NDB RWY 05  (GREENVILLE, SC)&#xA;KGYI NDB RWY 17L (SHERMAN-DENISON, TX)&#xA;KGYL NDB RWY 31  (GLENCOE, MN)&#xA;KGYY NDB RWY 30  (GARY, IN)&#xA;KHBV NDB RWY 13  (HEBBRONVILLE, TX)&#xA;KHDO NDB RWY 35R (HONDO, TX)&#xA;KHEG NDB-A       (JACKSONVILLE, FL)&#xA;KHFF NDB RWY 11  (CAMP MACKALL, NC)&#xA;KHFY NDB RWY 01  (INDIANAPOLIS, IN)&#xA;KHHG NDB RWY 09  (HUNTINGTON, IN)&#xA;KHHW NDB RWY 35  (HUGO, OK)&#xA;KHIO NDB-B       (PORTLAND, OR)&#xA;KHJH NDB RWY 12  (HEBRON, NE)&#xA;KHLN NDB-D       (HELENA, MT)&#xA;KHMY NDB RWY 17  (LEXINGTON, OK)&#xA;KHMY NDB RWY 35  (LEXINGTON, OK)&#xA;KHNZ NDB RWY 06  (OXFORD-HENDERSON, NC)&#xA;KHOC NDB RWY 23  (HILLSBORO, OH)&#xA;KHOE NDB RWY 14  (HOMERVILLE, GA)&#xA;KHOP NDB RWY 23  (FT CAMPBELL/HOPKINSVILLE, KY)&#xA;KHQG NDB RWY 02  (HUGOTON, KS)&#xA;KHQU NDB RWY 10  (THOMSON, GA)&#xA;KHRJ NDB RWY 23  (ERWIN, NC)&#xA;KHRO NDB RWY 18  (HARRISON, AR)&#xA;KHRU NDB RWY 17  (HERINGTON, KS)&#xA;KHRU NDB RWY 35  (HERINGTON, KS)&#xA;KHRX NDB RWY 20  (HEREFORD, TX)&#xA;KHSA NDB RWY 18  (BAY ST LOUIS, MS)&#xA;KHUA NDB RWY 17  (REDSTONE ARSENAL, AL)&#xA;KHUT NDB RWY 13  (HUTCHINSON, KS)&#xA;KHVC NDB RWY 26  (HOPKINSVILLE, KY)&#xA;KHVS NDB RWY 03  (HARTSVILLE, SC)&#xA;KHVS NDB RWY 21  (HARTSVILLE, SC)&#xA;KHYI NDB RWY 13  (SAN MARCOS, TX)&#xA;KHYW NDB RWY 04  (CONWAY, SC)&#xA;KHYW NDB RWY 22  (CONWAY, SC)&#xA;KHZD NDB RWY 01  (HUNTINGDON, TN)&#xA;KHZR NDB RWY 36  (NEW ROADS, LA)&#xA;KIAG NDB RWY 28R (NIAGARA FALLS, NY)&#xA;KICL NDB-A       (CLARINDA, IA)&#xA;KICT NDB RWY 01R (WICHITA, KS)&#xA;KIDA NDB RWY 20  (IDAHO FALLS, ID)&#xA;KIDP NDB RWY 35  (INDEPENDENCE, KS)&#xA;KIER NDB RWY 35  (NATCHITOCHES, LA)&#xA;KIIB NDB RWY 18  (INDEPENDENCE, IA)&#xA;KIKG NDB RWY 13  (KINGSVILLE, TX)&#xA;KILN NDB RWY 04L (WILMINGTON, OH)&#xA;KILN NDB RWY 22R (WILMINGTON, OH)&#xA;KIMT NDB RWY 01  (IRON MT-KINGSFORD, MI)&#xA;KINL NDB RWY 31  (INTERNATIONAL FALLS, MN)&#xA;KIOB NDB RWY 03  (MT STERLING, KY)&#xA;KIOB NDB RWY 21  (MT STERLING, KY)&#xA;KIPJ NDB RWY 23  (LINCOLNTON, NC)&#xA;KIRS NDB RWY 18  (STURGIS, MI)&#xA;KIRS NDB RWY 24  (STURGIS, MI)&#xA;KISB NDB RWY 17  (SIBLEY, IA)&#xA;KISB NDB RWY 35  (SIBLEY, IA)&#xA;KISN NDB RWY 29  (WILLISTON, ND)&#xA;KISW NDB RWY 02  (WISCONSIN RAPIDS, 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TX)&#xA;KUUV NDB RWY 24  (SULLIVAN, MO)&#xA;KUVA NDB RWY 33  (UVALDE, TX)&#xA;KUWL NDB RWY 09  (NEW CASTLE, IN)&#xA;KUWL NDB RWY 27  (NEW CASTLE, IN)&#xA;KVHN NDB RWY 21  (VAN HORN, TX)&#xA;KVIQ NDB RWY 28  (NEILLSVILLE, WI)&#xA;KVNC NDB RWY 31  (VENICE, FL)&#xA;KVNW NDB RWY 09  (VAN WERT, OH)&#xA;KVTA NDB RWY 09  (NEWARK, OH)&#xA;KVTN NDB RWY 32  (VALENTINE, NE)&#xA;KVUJ NDB RWY 22L (ALBEMARLE, NC)&#xA;KVVV NDB RWY 34  (ORTONVILLE, MN)&#xA;KWDR NDB RWY 31  (WINDER, GA)&#xA;KWJF NDB-C       (LANCASTER, CA)&#xA;KWYS NDB RWY 01  (WEST YELLOWSTONE, MT)&#xA;KXVG NDB RWY 31  (LONGVILLE, MN)&#xA;KYKM NDB RWY 27  (YAKIMA, WA)&#xA;KYKN NDB RWY 31  (YANKTON, SD)&#xA;KYNG NDB RWY 32  (YOUNGSTOWN-WARREN, OH)&#xA;KZEF NDB RWY 25  (ELKIN, NC)&#xA;KZPH NDB RWY 18  (ZEPHYRHILLS, FL)&#xA;KZPH NDB RWY 22  (ZEPHYRHILLS, FL)&#xA;KZPH NDB RWY 36  (ZEPHYRHILLS, FL)&#xA;L39  NDB RWY 36  (LEESVILLE, LA)&#xA;L67  NDB-A       (RIALTO, CA)&#xA;M02  NDB RWY 17  (DICKSON, TN)&#xA;M18  NDB RWY 16  (HOPE, AR)&#xA;MYSM NDB RWY 10  (SAN SALVADOR, , BHS)&#xA;N94  NDB-B       (CARLISLE, PA)&#xA;NY0  NDB RWY 10  (JOHNSTOWN, NY)&#xA;NY0  NDB RWY 28  (JOHNSTOWN, NY)&#xA;S01  NDB RWY 24  (CONRAD, MT)&#xA;S39  NDB RWY 10  (PRINEVILLE, OR)&#xA;T41  NDB RWY 30  (LA PORTE, TX)&#xA;T85  NDB RWY 31  (YOAKUM, TX)&#xA;TX25 NDB RWY 17  (ATHENS, TX)&#xA;U68  NDB RWY 09  (COWLEY-LOVELL-BYRON, WY)&#xA;U76  NDB RWY 28  (MOUNTAIN HOME, ID)&#xA;X50  NDB RWY 18  (NEW SMYRNA BEACH, FL)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-23T18:50:35.940" LastActivityDate="2014-04-23T18:50:35.940" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3548" PostTypeId="1" AcceptedAnswerId="3551" CreationDate="2014-04-22T21:59:46.807" Score="6" ViewCount="3217" Body="&lt;p&gt;I'm at a loss between regulations &lt;code&gt;§91.146&lt;/code&gt; (Passenger-carrying flights for the benefit of a charitable, nonprofit, or community event.) and &lt;code&gt;§61.113&lt;/code&gt; (Private pilot privileges and limitations: Pilot in command.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;§91.146&lt;/code&gt; contains language that allows a private pilot (who meets 500 hour requirement, among other items) to operate as PIC for a charitable event. The language emphasizes that if the event doesn't meet the charity requirement, it is to be considered commercial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do these restrictions under &lt;code&gt;§91.146&lt;/code&gt; / &lt;code&gt;§61.113(d)&lt;/code&gt; apply if a pilot is willing to PIC under the criteria of &lt;code&gt;§61.113(a)&lt;/code&gt; and cover all expenses of the flight?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§61.113   Private pilot privileges and limitations: Pilot in command.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraphs (b) through (h) of this section,&#xA;  no person who holds a private pilot certificate may act as pilot in&#xA;  command of an aircraft that is carrying passengers or property for&#xA;  compensation or hire; nor may that person, for compensation or hire,&#xA;  act as pilot in command of an aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;....&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) A private pilot may act as pilot in command of a charitable,&#xA;  nonprofit, or community event flight described in §91.146, if the&#xA;  sponsor and pilot comply with the requirements of §91.146.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="178" LastEditorUserId="178" LastEditDate="2014-04-22T22:08:13.310" LastActivityDate="2015-12-30T21:01:39.327" Title="Does 14 CFR 91.146 (Charitable Events) apply if the pilot does not seek compensation or hire?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3549" PostTypeId="2" ParentId="3455" CreationDate="2014-04-22T22:25:40.353" Score="5" Body="&lt;p&gt;As far as I recall the priority button suppresses the other stick &lt;strong&gt;and autopilot&lt;/strong&gt;. Since it is right under the thumb on the side-stick, that makes it quicker way to disconnect autopilot than navigating the other hand to the flight management panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The overall idea is that when the pilot needs to make manual input quickly they simply push that button and it will ensure that input will be obeyed, so they don't need to think what state the system was in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that the priority take-over button will disconnect autopilot immediately when pressed, but it only disables the other side-stick while held down, or permanently when held down for more than 40 seconds. The last case is primarily for situations when the other pilot is incapacitated holding their side-stick deflected or when the other side-stick fails.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2017-07-29T09:32:14.027" LastActivityDate="2017-07-29T09:32:14.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3550" PostTypeId="2" ParentId="3548" CreationDate="2014-04-23T02:03:43.083" Score="3" Body="&lt;p&gt;This basically boils down to whether or not &lt;strong&gt;anybody&lt;/strong&gt; is receiving compensation, not just the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are just giving people a ride, with no payment to the charity or yourself, then 14 CFR 91.146 wouldn't apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if they are paying the charity for the flight, even if you accept no compensation, the flight is for hire and the rules of 91.146 apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is any question, the FAA will very likely &quot;connect the dots&quot; between a charitable contribution and the ensuing flight, even if the purpose of the donation wasn't explicitly stated as for the aircraft ride.  They take a very dim view of trying to bypass the regulations like that.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-23T02:03:43.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3551" PostTypeId="2" ParentId="3548" CreationDate="2014-04-23T02:04:34.133" Score="5" Body="&lt;p&gt;Let's look at this from two angles -- first, what's OK under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2.5.1.8&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.113&lt;/a&gt; (basically &amp;quot;no compensation except the pro-rata sharing of expenses&amp;quot; when acting as a private pilot).&lt;/p&gt;&#xA;&lt;p&gt;The FAA has an &lt;em&gt;incredibly&lt;/em&gt; broad interpretation of &amp;quot;compensation&amp;quot; - The foundational counsel opinion is an interpretation to &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2005/kirwan%20-%20(2005)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Joseph A. Kirwan&lt;/a&gt;, and if you &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/?year=all&amp;amp;q=Kirwan&amp;amp;bSubmit=Search&quot; rel=&quot;nofollow noreferrer&quot;&gt;search counsel opinions for &lt;code&gt;Kirwan&lt;/code&gt;&lt;/a&gt; you find a bunch of additional opinions referencing it.&lt;br /&gt;&#xA;Basically Kirwan and the other opinions state that the receipt of &lt;em&gt;anything of value&lt;/em&gt; is compensation.&lt;br /&gt;&#xA;That could include:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Money, obviously.&lt;/li&gt;&#xA;&lt;li&gt;Free or discount fuel/oil&lt;/li&gt;&#xA;&lt;li&gt;Free meal&lt;/li&gt;&#xA;&lt;li&gt;Lodging&lt;/li&gt;&#xA;&lt;li&gt;Logging of flight time (if you're not responsible for the operating expenses of the aircraft)&lt;/li&gt;&#xA;&lt;li&gt;The receipt of a benefit (usually money) by the &lt;em&gt;organizer&lt;/em&gt; (charity)&lt;br /&gt;&#xA;(&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2010/weybrecht%20-%20(2010)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weybrecht, 2010&lt;/a&gt; - if they get the ride in exchange for a donation or attendance fee it's 91.146)&lt;/li&gt;&#xA;&lt;li&gt;&amp;quot;Valuable Good Will&amp;quot;&lt;br /&gt;&#xA;(Again in Weybrecht from above - so yeah, If you fly your buddy somewhere and they &amp;quot;owe you one&amp;quot; that might be a violation.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;There's really &lt;em&gt;almost nothing&lt;/em&gt; you can do under 61.113 except fly somewhere for a hundred-dollar hamburger and split the cost of gas (under the FARs you even have to pay your pro rata share of the burger) - it's very restrictive.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Now let's look at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?&amp;amp;rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.2.4.28&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.146&lt;/a&gt; - like &lt;a href=&quot;https://aviation.stackexchange.com/questions/3548/does-14-cfr-91-146-charitable-events-apply-if-the-pilot-does-not-seek-compensa#comment6950_3548&quot;&gt;DJClayworth pointed out&lt;/a&gt; what this  basically does is carve out a small set of exceptions that allow community groups and charitable organizations which have friendly pilots to offer &amp;quot;airplane rides&amp;quot; in exchange for a donation without being in violation of the FARs (risking the friendly pilot's certificate, and the possible wrath of the FAA on the organizer).&lt;/p&gt;&#xA;&lt;p&gt;There are lots of restrictions (Like the 500 hour requirement, the requirement that flights be &amp;quot;Nonstop, beginning and ending at the same airport, and within 25 miles of the airport of origin&amp;quot;, the limit of reimbursement for the pilot being &amp;quot;pro rata share of expenses&amp;quot;, and notification of the local FSDO).&lt;/p&gt;&#xA;&lt;p&gt;The FAA wants to basically make sure pilots are not flying tons of these charity flights every year to basically build time, and that charities aren't operating &lt;em&gt;de facto&lt;/em&gt; air tour companies under the exemptions of 91.146.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;So what's the answer to your question?&lt;/h1&gt;&#xA;&lt;p&gt;Basically &lt;em&gt;If the organization is getting donations/admission fees/raffle proceeds, etc. in exchange for these flights the operation falls under 91.146&lt;/em&gt; (because the charity is receiving compensation -- the donation).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-04-23T03:43:09.467" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3552" PostTypeId="2" ParentId="3455" CreationDate="2014-04-23T04:20:36.893" Score="5" Body="&lt;p&gt;I'm not sure it exactly answers your question, but there is an excellent example of why this feature ought to always be used in an emergency situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447#Final_report&quot; rel=&quot;nofollow&quot;&gt;Air France Flight 447&lt;/a&gt; was an Airbus A330, I'm not entirely certain if it had this feature (I assume so?)  Anyway, it went into a stall somewhere near cruise altitude and the co-pilot, for some unknown reason, kept pulling back on the right stick.  Eventually the plane was at a 40 degree incline and losing altitude quickly.  The pilot on the left stick noticed the the stall and tried to push the plane forward to correct, but found the controls to be unresponsive, he was apparently unaware that the right stick was pulled fully back. The plane stayed in that stall all the way until it crashed into the Atlantic Ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an emergency, it's really really important to have a single input or a &quot;single source of truth&quot;, not matter what industry you're in (I hear it all the time in software development anyway.)  I'd argue that this is the main reason they have that override switch.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2014-11-20T17:54:21.183" LastActivityDate="2014-11-20T17:54:21.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3553" PostTypeId="2" ParentId="225" CreationDate="2014-04-23T08:51:58.207" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://ourairports.com&quot; rel=&quot;nofollow&quot;&gt;OurAirports&lt;/a&gt;, the continuation of DAFIF by community effort (since Australia (and possibly some other countries) copyrighted their official data) would be the obvious one.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-04-23T08:51:58.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3554" PostTypeId="1" AcceptedAnswerId="3563" CreationDate="2014-04-23T08:59:04.803" Score="12" ViewCount="1409" Body="&lt;p&gt;Please note that I'm not asking about getting a &lt;em&gt;certificate&lt;/em&gt; good enough for flying a wide-body passenger jet (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1255/what-does-it-cost-to-get-an-atp-certificate-from-scratch&quot;&gt;related question&lt;/a&gt;). Rather, I'm asking about getting from zero flying experience to an &lt;strong&gt;actual pilot/co-pilot job&lt;/strong&gt; at a &lt;strong&gt;major&lt;/strong&gt; US airline (AA/Delta/UA/Southwest).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps some regulatory organization maintains such a statistics? Or even the airlines themselves? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm well aware that people can have various career paths (from ex-military pilots to guys who paid for 10000 flights hours out of their pockets), but with 40,000+ pilots employed by major airlines there must be a statistically-significant median experience.&lt;/p&gt;&#xA;" OwnerUserId="2172" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-30T02:52:42.210" Title="What is the average cost/timeframe of obtaining a pilot job at a major passenger airline in the US?" Tags="&lt;airline-operations&gt;&lt;flight-training&gt;&lt;usa&gt;&lt;career&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3555" PostTypeId="2" ParentId="3519" CreationDate="2014-04-23T09:20:46.863" Score="13" Body="&lt;h1&gt;Advantages&lt;/h1&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Compression-ignition engines have higher compression ratio which leads to being more efficient. So the aircraft range improves and on longer flights payload capacity may improve as well. Fuel consumption is usually about 30% lower.&lt;/li&gt;&#xA;&lt;li&gt;The higher efficiency combined with the fact that Jet A-1 fuel is cheaper mean they have lower operating cost. Especially since in Europe the leaded avgas is heavily taxed to discourage it's use for environmental concerns.&lt;/li&gt;&#xA;&lt;li&gt;They should be a bit more reliable. A diesel engine needs high pressure fuel pump, but apparently there are less problems with those than there are with spark-plugs.&lt;/li&gt;&#xA;&lt;li&gt;They are somewhat easier to operate, since they don't have separate throttle and mixture controls.&lt;/li&gt;&#xA;&lt;li&gt;They don't suffer the problems associated with incorrect settings of those controls, namely knocking/detonation and pre-ignition.&lt;/li&gt;&#xA;&lt;li&gt;Turbo-charging them does not carry the risk of pre-ignition and most of them are turbo-charged, so the performance does not decline as fast with density altitude.&lt;/li&gt;&#xA;&lt;li&gt;There is lower risk of fire since jet/diesel fuel is less flammable (has higher ignition temperature).&lt;/li&gt;&#xA;&lt;li&gt;Jet A-1 has much wider availability, especially in the third world, so it's easier to plan for fuel stops on a flight through say, Latin America or Africa&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;h1&gt;Disadvantages&lt;/h1&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;They are heavier for the same power, because they need to be made from stronger material due to the higher compression ratio and because they need to have larger cylinder volume because of lower maximal rpm. On longer flights the reduction in fuel weight often makes up for the heavier engine.&lt;/li&gt;&#xA;&lt;li&gt;Turbo-charging comes with specific operating procedures unfamiliar to those used to normally aspirated engines and a slight lag in thrust lever (it's not a throttle) response.&lt;/li&gt;&#xA;&lt;li&gt;As others mentioned, small airports may not have jet fuel yet. This is probably better in Europe where the pressure to phase out 100LL avgas is stronger. Some engines also use automobile diesel fuel or even either jet or diesel fuel as diesel engines are less picky about what they burn.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-06-16T11:37:06.613" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="3556" PostTypeId="2" ParentId="3533" CreationDate="2014-04-23T14:20:05.513" Score="-2" Body="&lt;p&gt;you can register the aircraft in a different jurisdiction and use the same last part of the registration and change only the first 1 or 2 codes&lt;/p&gt;&#xA;" OwnerUserId="2187" LastActivityDate="2014-04-23T14:20:05.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3557" PostTypeId="2" ParentId="2045" CreationDate="2014-04-23T16:21:51.940" Score="1" Body="&lt;p&gt;I remember I got a free hour from American Flyers when I told them I was thinking about switching to them in the middle of my instrument rating training.  Not sure if they do that for intro flights as well.&lt;/p&gt;&#xA;" OwnerUserId="390" LastActivityDate="2014-04-23T16:21:51.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3559" PostTypeId="1" AcceptedAnswerId="3560" CreationDate="2014-04-23T16:33:06.767" Score="19" ViewCount="2708" Body="&lt;p&gt;As a new VFR pilot, I was wondering why anyone would fly (or be assigned) an ILS (or other) approach in clear weather?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I ask this because I watched Vienna - Tokyo (Narita) on PilotsEye.tv where the F.O. flew the approach looking at the display all the way until the flare. The visibility was good. Runway 34R.&lt;/p&gt;&#xA;" OwnerUserId="1868" LastEditorUserId="572" LastEditDate="2015-02-19T09:42:36.310" LastActivityDate="2015-02-19T09:42:36.310" Title="What are the reasons for using an instrument approach on a clear day / CAVOK?" Tags="&lt;safety&gt;&lt;approach&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3560" PostTypeId="2" ParentId="3559" CreationDate="2014-04-23T16:51:13.200" Score="24" Body="&lt;p&gt;There are actually quite a few reasons to fly an instrument approach, especially one with vertical guidance (like an ILS), even if the weather doesn't require it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It serves as a backup to the visual approach.  There are various visual illusions that can cause a pilot to fly an approach too high or too low and monitoring the vertical guidance can help to mitigate those.&lt;/li&gt;&#xA;&lt;li&gt;It helps to ensure that you land on the correct runway, and even at the correct airport.  (Unlike &lt;a href=&quot;http://edition.cnn.com/2014/01/13/travel/southwest-plane-wrong-airport/&quot;&gt;this airplane&lt;/a&gt;.)&lt;/li&gt;&#xA;&lt;li&gt;ATC uses it when pilots do not have the airport or runway in sight.  This happens quite frequently at large airports where they have to line many aircraft up on final.   The last guy is a long distance from the airport so may not be able to see it but can fly the approach.&lt;/li&gt;&#xA;&lt;li&gt;It can be useful if it is hazy or the sun is making it hard for the pilots to find the airport.&lt;/li&gt;&#xA;&lt;li&gt;Some parallel runways are approved for simultaneous approaches (as is the case at Narita for runways 34L &amp;amp; 34R) so ATC will clear two airplanes for the respective ILS's.  This keeps them tracking the centerline of the approach instead of maneuvering visually where they might drift over into the way of the other airplane.  &lt;/li&gt;&#xA;&lt;li&gt;Flying the approach on the autopilot leaves more time for the pilot to focus on other things and possibly catch something that might have been missed while hand flying a visual approach.&lt;/li&gt;&#xA;&lt;li&gt;Sometimes instrument approaches are used for noise abatement reasons.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If I had to guess about the particular approach that you mention, I would say that it is probably company SOP (Standard Operating Procedures) to fly the ILS whenever possible for the safety benefits, and that Narita allows simultaneous parallel landings to the two runways so ATC would require it as well.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-23T23:59:42.710" LastActivityDate="2014-04-23T23:59:42.710" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3561" PostTypeId="2" ParentId="3559" CreationDate="2014-04-23T16:56:37.690" Score="8" Body="&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/3560/64&quot;&gt;serving as a good cross-check for the visual procedure&lt;/a&gt; (which is probably the case here - one pilot looks down, one pilot looks out) there's at least one other reason I can think of for a pilot to request &amp;amp; fly an instrument approach:&lt;br&gt;&#xA;In order to maintain currency to act as pilot in command under instrument flight rules a pilot must log a certain number of instrument approaches within a given calendar period (in the USA it's 6 approaches in the last 6 months, plus &quot;holding patterns; and Intercepting and tracking courses through the use of navigation systems.&quot;, except for gliders which have a different requirement).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All other things being equal, if your currency is about to lapse you might request to fly an instrument approach (including one turn in a holding pattern) on a VMC day (with a view limiting hood and a safety pilot on board) to maintain currency on.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-04-23T18:45:39.993" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3562" PostTypeId="2" ParentId="3559" CreationDate="2014-04-23T17:03:41.290" Score="17" Body="&lt;p&gt;There are three reasons I can think of:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Noise abatement&lt;/strong&gt;&lt;br&gt;&#xA;I know that it is not allowed to fly visual approaches at many european airports due to noise abatement. They prohibit it to avoid aircraft flying over residential areas left and right of the approach path &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Traffic flow&lt;/strong&gt;&lt;br&gt;&#xA;At many international airports (e.g. Tokyo) they have to use every second to manage the huge amount of traffic. Lining up the aircraft on an ILS with an assigned speed is the most efficient way.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Practice / Safety&lt;/strong&gt;&lt;br&gt;&#xA;There are many airlines which tell their pilots not to do visual approaches. This should enhance safety (stabilized approaches) and keep the pilots well prepared for low visibility operations. Sometimes you even practice autoland in VMC to keep current.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="343" LastEditorUserId="64" LastEditDate="2014-04-23T17:36:17.773" LastActivityDate="2014-04-23T17:36:17.773" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3563" PostTypeId="2" ParentId="3554" CreationDate="2014-04-24T00:07:36.937" Score="7" Body="&lt;p&gt;The distribution of how pilots get to the majors is bimodal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can get a military pilot slot and give 4-10 years to the USAF, you can then get an FAA ATP and start interviewing at whatever majors are hiring and have your ex-mil buddies on the hiring board. Great way to get in at FedEx or UPS. This costs a few grand for your ATP but that's about it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can't get a military slot, getting up to the point you can instruct from nothing can vary wildly in cost. The accelerated flight training programs will do this for around $70,000. Next you instruct until you hit 135 mins and do either that or instructing. At this point you shouldn't be paying for time anymore. When you get on at a regional you'll sit right seat for a few to many years then you'll upgrade. After about 1.5-2 years in the left seat you'll have the bare minimums to apply at a major. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-24T00:07:36.937" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3564" PostTypeId="1" AcceptedAnswerId="3567" CreationDate="2014-04-24T03:38:34.910" Score="17" ViewCount="7771" Body="&lt;p&gt;1) Is $V_1$ used to determine minimum runway length? How is $V_1$ calculated?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) If it is used to determine the minimum runway length, and for example we have a runway of 8000 ft and my airplane's accelerate stop distance required (ASDR) is 4000 ft and takeoff distance required (TODR) is 5000 ft, &lt;strong&gt;can my $V_1$ be as low as 15 kts?&lt;/strong&gt; Since (let's say) below 15 kts, of course you will have the 4000 ft required to stop and also have enough distance to takeoff with 1 engine inoperative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Let's say we have a very long runway so an airplane can make a rejected takeoff even at rotation speed ($V_R$). Can $V_1$ be the same as $V_R$?&lt;/p&gt;&#xA;" OwnerUserId="1990" LastEditorUserId="1696" LastEditDate="2015-02-19T18:44:44.510" LastActivityDate="2017-03-11T20:20:48.843" Title="How is minimum runway length related to V1?" Tags="&lt;aircraft-performance&gt;&lt;v-speeds&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3565" PostTypeId="2" ParentId="3564" CreationDate="2014-04-24T04:50:40.743" Score="11" Body="&lt;p&gt;Just to make sure we're on the same page, I'll reiterate what should be obvious: $V_1$ is a speed at which you may stop in the available runway space or continue the takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, $V_1$ could be any speed that matches this criteria -- it is not &lt;em&gt;necessarily&lt;/em&gt; one speed. However, in practice we refer to a few different $V_1$ speeds:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Minimum $V_1$&lt;/li&gt;&#xA;&lt;li&gt;Balanced $V_1$ (distance to takeoff is the same as distance to stop)&lt;/li&gt;&#xA;&lt;li&gt;Maximum $V_1$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The reason why $V_1$ cannot be greater than $V_R$ is that you're already or about to be in the air. If you attempt to stop the aircraft rotating, you might be too aggressive and destroy the aircraft by tring to force the airplane down during or after rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also can't have a $V_1$ of something like 15 knots, as it may not be below $V_{MCG}$. If you did continue with full thrust on one engine at 15 knots, you would not have enough authority from the rudder to prevent the aircraft going off the edge of the runway, which is extremely dangerous. This is even more of an issue if you decide to continue the takeoff at $V_1$, which would almost certainly result in a runway excursion. Typical $V_{MCG}$ values for airliners can be above 100 knots, making your proposed situation impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all cases, using the balanced $V_1$ provides the minimum runway distance required, though company policy may require using a reduced $V_1$.&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="72" LastEditDate="2014-04-24T11:38:17.187" LastActivityDate="2014-04-24T11:38:17.187" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3566" PostTypeId="1" AcceptedAnswerId="3843" CreationDate="2014-04-24T05:27:23.633" Score="7" ViewCount="1262" Body="&lt;p&gt;Is there a Canadian law or regulation which requires me to have my Radiotelephone Operator's Restricted Certificate (Aeronautical) on-board the aircraft with me?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what I've found so far:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Canada requires you to &lt;em&gt;hold&lt;/em&gt; the certificate (&lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-484/page-7.html#h-33&quot; rel=&quot;nofollow&quot;&gt;Radiocommunications regulations, Part V, Section 33&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A person may operate radio apparatus in the aeronautical service, maritime service or amateur radio service only where the person holds an appropriate radio operator certificate [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, I can't find a regulation saying I need the piece of paper with me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of the wording Canada uses in its regulations to say that you need to actually have the document with you is at &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/page-75.html&quot; rel=&quot;nofollow&quot;&gt;CARS 401.03 (1)(d)&lt;/a&gt; (regarding pilot licences):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the person can produce the permit, licence or rating, and the certificate, when exercising those privileges.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can't find that wording or anything like it relating to my radio operator's certificate in the CARS, the Radiocommunications Regulations, the Aeronautics Act, or the Radiocommunications Act.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="69" LastEditDate="2014-04-24T17:38:05.483" LastActivityDate="2014-05-13T14:53:16.423" Title="Am I required to have my Radiotelephone Operator's Restricted Certificate (Aeronautical) on-board the aircraft with me?" Tags="&lt;radio-communications&gt;&lt;transport-canada&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3567" PostTypeId="2" ParentId="3564" CreationDate="2014-04-24T16:46:25.317" Score="28" Body="&lt;h1&gt;Takeoff Field Length&lt;/h1&gt;&#xA;&lt;p&gt;The “FAR” Takeoff Field Length determined from the FAA Approved Airplane Flight Manual (AFM) considers the most limiting of each of the following three criteria:&lt;/p&gt;&#xA;&lt;h3&gt;1) All-Engine Go Distance:&lt;/h3&gt;&#xA;&lt;p&gt;115% of the actual distance required to accelerate, liftoff and reach a point 35 feet above the runway with all engines operating:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nwMWz.png&quot; alt=&quot;All-Engine Go Distance&quot; /&gt;&lt;/p&gt;&#xA;&lt;h3&gt;2) Engine-Out Accelerate-Go Distance:&lt;/h3&gt;&#xA;&lt;p&gt;The distance required to accelerate with all engines operating, have one engine fail at &lt;span class=&quot;math-container&quot;&gt;$V_{EF}$&lt;/span&gt; at least one second before &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;, continue the takeoff, liftoff and reach a point 35 feet above the runway surface at &lt;span class=&quot;math-container&quot;&gt;$V_2$&lt;/span&gt; speed:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pHve8.png&quot; alt=&quot;Engine-Out Accelerate-Go Distance&quot; /&gt;&lt;/p&gt;&#xA;&lt;h3&gt;3) Accelerate-Stop Distance:&lt;/h3&gt;&#xA;&lt;p&gt;The distance required to accelerate with all engines operating, have an engine failure or some other event at &lt;span class=&quot;math-container&quot;&gt;$V_{EVENT}$&lt;/span&gt; at least one second before &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;, recognize the event, reconfigure for stopping and bring the airplane to a stop using maximum wheel braking with the speed brakes extended.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MdyzV.png&quot; alt=&quot;Accelerate-Stop Distance&quot; /&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;&lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; Speed&lt;/h1&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; is the speed chosen by the manufacturer as &amp;quot;the pilot’s initiation of the first action to stop the airplane during the accelerate-stop tests.&amp;quot;  Note that this is particularly important in that it is &lt;strong&gt;not&lt;/strong&gt; a &lt;em&gt;takeoff decision speed&lt;/em&gt; as some pilots like to think of it.  The decision must have been made &lt;em&gt;&lt;strong&gt;prior&lt;/strong&gt;&lt;/em&gt; to &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; so that there is time to &lt;strong&gt;react&lt;/strong&gt; by &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;This speed is chosen by the manufacturer and must be between the engine failure speed&lt;sup&gt;1&lt;/sup&gt; and rotation speed.  Within this range, they could choose any speed, but typically they choose the speed which gives a balanced field length (see next section).&lt;/p&gt;&#xA;&lt;p&gt;There are also other factors to consider such as the maximum brake energy limit (&lt;span class=&quot;math-container&quot;&gt;$V_{MBE}$&lt;/span&gt;) which will prevent &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; from being too high.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Balanced Field Length&lt;/h1&gt;&#xA;&lt;p&gt;If we takeoff from a fixed length runway (like, say one that matches the Takeoff Field Length from above), changing the &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; speed will affect the weight that we can successfully continue the takeoff or abort within the available runway.&lt;/p&gt;&#xA;&lt;p&gt;At a particular weight, a lower &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; will enable us to stop sooner if we abort but will take more distance to continue the takeoff.  A higher &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; will require more distance to stop but will take less distance to continue.  If we graph these values, there will be a point where the &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; speeds for the abort/continue lines meet, and this is known as the balanced field length.  It is the value typically given in the AFM:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0CwCJ.png&quot; alt=&quot;Balanced Field Length&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;This is nice because it gives the pilot one important number to remember instead of different stop/continue &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;'s.&lt;/p&gt;&#xA;&lt;p&gt;If they were to choose an extremely low &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; as in your question, then it would require considerably more runway in order to continue the takeoff than if it were higher, and it would not be balanced.  Some AFM's do include separate charts for accelerate-go and accelerate-stop though so you could figure out exactly how much runway that you would need if the engine failed at a lower airspeed.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Rotation Speed&lt;/h1&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_R$&lt;/span&gt; is determined independently from &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;, and if it is ever less than &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt; then it must be raised to be equal to &lt;span class=&quot;math-container&quot;&gt;$V_1$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;References&lt;/h1&gt;&#xA;&lt;p&gt;The regulatory information for takeoff performance on transport category aircraft is listed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d971bef1e10197ebb42c7912d4baec1a&amp;amp;node=14:1.0.1.3.11.2.155&amp;amp;rgn=div7&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Part 25, Subpart B, Performance&lt;/a&gt;, 25.101 - 25.113.&lt;/p&gt;&#xA;&lt;p&gt;Of particular interest for this question would be &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d971bef1e10197ebb42c7912d4baec1a&amp;amp;node=14:1.0.1.3.11.2.155.11&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.107 - Takeoff speeds&lt;/a&gt; and  &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d971bef1e10197ebb42c7912d4baec1a&amp;amp;node=14:1.0.1.3.11.2.155.14&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.113 - Takeoff distance and takeoff run&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;An easier to read document is the FAA's &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/takeoff_safety.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot Guide to Takeoff Safety&lt;/a&gt; which covers this and a lot more.  Much of my answer was taken directly from this document, and I would highly recommend anyone that is flying a multi-engine aircraft to read the entire thing.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;span class=&quot;math-container&quot;&gt;$V_{EF}$&lt;/span&gt; itself must be above the minimum controllable airspeed on the ground plus acceleration while the pilot reacts to the engine failure.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-03-11T20:20:48.843" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3569" PostTypeId="1" AcceptedAnswerId="3570" CreationDate="2014-04-25T11:18:14.687" Score="9" ViewCount="3480" Body="&lt;p&gt;I know that both land and sea planes require pilot ratings in order to act as pilot-in-command. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the requirement to act as pilot-in-command of an &lt;a href=&quot;http://en.wikipedia.org/wiki/Amphibious_aircraft&quot; rel=&quot;nofollow&quot;&gt;amphibian&lt;/a&gt;? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a third rating or just seaplane and land ratings? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about flights taking off and landing exclusively on either water or land but not both?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="14661" LastEditDate="2016-05-30T17:16:21.240" LastActivityDate="2016-05-31T20:25:11.590" Title="What are the pilot rating requirements for amphibians?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;amphibian&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3570" PostTypeId="2" ParentId="3569" CreationDate="2014-04-25T12:49:01.890" Score="11" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.seaplanepilotsassociation.org/resources/faq/airman-issues/&quot; rel=&quot;nofollow&quot;&gt;Seaplane Pilots Association&lt;/a&gt; you can operate an amphibious airplane on hard-surface runways with a land class rating but need a seaplane class rating to take off or land on water, and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the regs, it seems that the airplane can simply be considered either land or seaplane class depending on how you are operating it.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="62" LastEditDate="2016-05-31T20:25:11.590" LastActivityDate="2016-05-31T20:25:11.590" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3571" PostTypeId="5" CreationDate="2014-04-25T15:19:50.347" Score="0" Body="&lt;p&gt;questions about planes that can land on both water and land.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-05T19:46:02.953" LastActivityDate="2014-05-05T19:46:02.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3572" PostTypeId="4" CreationDate="2014-04-25T15:19:50.347" Score="0" Body="questions about planes that can land on both water and land." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-25T15:32:08.973" LastActivityDate="2014-04-25T15:32:08.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3573" PostTypeId="1" AcceptedAnswerId="3574" CreationDate="2014-04-25T16:07:38.247" Score="27" ViewCount="10140" Body="&lt;p&gt;Here's the scenario: I was a student pilot on inbound for landing at my home airport on my final solo cross country flight I needed before doing a checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At roughly 8 miles out to the north west, I established contact with the tower and was told to &quot;enter left base, runway 7, report 3 miles out.&quot; I interpreted the &quot;report 3 miles out&quot; as to give the tower a call when I was 3 miles away from the field, ie, when my GPS indicated I was 3 miles from the field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, it was the most windy day I had flown solo in so far (15kt gusts) so I wanted to make sure I had ample time to line up with the runway on final and get a feeling for how the winds were blowing since the ATIS reported them as being variable in direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, what I ended up doing was making a wide base, except apparently I made it a little too wide because the GPS did not indicate I was 3 miles from the field until I was on final. At this point, I called the tower, reported I was on a 3 mile final and was given clearance to land. After landing, I still had no idea I had done anything incorrectly as the controller made no indication to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few hours after I landed, my CFI sent me a text message asking me how &quot;report a 3 mile base&quot; meant &quot;report a 3 mile final and fly a straight in approach.&quot; I'm not sure if he was on the frequency when it happened or if the tower controller called him after the fact and told him about it because I was told to &quot;report 3 miles out&quot;, not &quot;report 3 mile base.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I completely understand that I made my base leg too wide and that caused me to deviate from an ATC instruction. What I'm wondering is how bad of a screw up is this? My CFI's reaction was one of legitimate anger and it makes me want to stay on the ground for a while.&lt;/p&gt;&#xA;" OwnerUserId="2207" LastEditorUserId="64" LastEditDate="2014-04-25T22:44:47.323" LastActivityDate="2021-02-09T03:13:19.940" Title="I accidentally deviated from an ATC instruction as a student pilot. How bad was it?" Tags="&lt;air-traffic-control&gt;&lt;flight-training&gt;&lt;student-pilot&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3574" PostTypeId="2" ParentId="3573" CreationDate="2014-04-25T16:56:25.267" Score="34" Body="&lt;p&gt;Well, you screwed up, but nobody got hurt, no metal was bent, and since the tower didn't yell at you presumably you didn't &lt;em&gt;obviously&lt;/em&gt; endanger anyone's safety (though there's always some level of risk when an aircraft isn't where the tower expects it to be).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as deviations go, that's not &lt;em&gt;good&lt;/em&gt;, but it's not terrible. The tower was probably expecting you to report 3 miles out, continuing in to about a mile from the field for your downwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Schedule an extra half hour of ground time with your CFI before your next flight to talk about what happened. Also take the time to fill out &lt;a href=&quot;http://asrs.arc.nasa.gov&quot;&gt;an ASRS report explaining what happened and why&lt;/a&gt; (It's probably unnecessary in this case, as a student the tower will almost certainly be satisfied with you getting &quot;a good talking-to&quot; from your instructor, but it's a good way to learn how that system works.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are a couple of other things you might want to do on your next few training flights:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Spend some time getting comfortable in the pattern on windy days.&lt;/strong&gt;&lt;br&gt;&#xA;You should be comfortable in a tighter pattern than 3 miles, even on a windy day (see my next item for why). This takes practice, and fortunately for you it's spring (at least in the USA) so there are plenty of windy days in most of the country!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Practice some engine-out approaches to get a feel for your plane's glide performance.&lt;/strong&gt;&lt;br&gt;&#xA;A base leg 3 miles out in a typical GA trainer is &lt;em&gt;very&lt;/em&gt; wide -- Remember you generally want to be able to make &lt;em&gt;some spot on the runway&lt;/em&gt; if your engine quits on downwind, and you probably can't do that from 1000 feet AGL at 3 miles out.&lt;br&gt;&#xA;Take a few laps around the pattern and have your instructor pull the power at various points so you have a feeling for how the energy management works out - this will give you a good feel for how wide your pattern should be.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Turn the GPS &lt;em&gt;off&lt;/em&gt; and practice flying visually.&lt;/strong&gt;&lt;br&gt;&#xA;The GPS is one link link in your error chain, but I think it's a &lt;em&gt;big one&lt;/em&gt;: If you were flying visually and relying on landmarks to judge your distance rather than the 3 mile alert from your GPS you might have realized &quot;Hey, I'm entering downwind - I should tell the tower!&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-25T16:56:25.267" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3575" PostTypeId="1" AcceptedAnswerId="3576" CreationDate="2014-04-26T00:54:42.007" Score="23" ViewCount="8181" Body="&lt;p&gt;During visual flight conditions, when you see another aircraft in your path, you should strive to avoid hitting it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In shipping there are standard international rules about which way boats should turn in order to avoid each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there similar rules in aviation?&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="69" LastEditDate="2014-04-26T05:01:47.987" LastActivityDate="2014-06-05T07:43:59.987" Title="Which way should you turn to avoid another aircraft?" Tags="&lt;see-and-avoid&gt;&lt;vmc&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3576" PostTypeId="2" ParentId="3575" CreationDate="2014-04-26T01:36:55.120" Score="28" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;In shipping there are standard international rules about which way boats should dodge each other.&lt;br&gt;&#xA;  Are there similar rules in aviation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why yes, there are - in fact they're basically similar to the maritime rules!&lt;br&gt;&#xA;They're described in &lt;a href=&quot;http://www.icao.int/Meetings/anconf12/Document%20Archive/an02_cons%5b1%5d.pdf&quot;&gt;ICAO Annex 2&lt;/a&gt; (or for US pilots, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.2.4.7&quot;&gt;FAR 91.113&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, for aircraft of the same type (e.g. two airplanes) &lt;em&gt;in the air&lt;/em&gt; the rules are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Approaching head-on:&lt;/strong&gt; Both aircraft alter their heading to the &lt;em&gt;right&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Converging:&lt;/strong&gt; Give way to the aircraft on &lt;em&gt;your right&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Overtaking:&lt;/strong&gt; Pass &quot;well clear&quot; to the right of the aircraft being overtaken.&lt;br&gt;&#xA;(The aircraft being overtaken has the right of way. The overtaking plane maneuvers to remain clear.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The rules for converging aircraft are more complex when the aircraft are not the same type - basically the more maneuverable aircraft gives way to the less maneuverable aircraft (because something like a balloon can't really maneuver to avoid a collision) - you can read the details in either of the links above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also while it's not explicitly spelled out in ICAO Annex 2 (or at least I didn't see it) aircraft in distress generally trump the &quot;right of way&quot; rules. (This is really common sense: if an aircraft is recognizably in distress you do everything in your power to stay out of their way and help ensure a safe outcome to whatever their situation is.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-04-26T01:36:55.120" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3577" PostTypeId="1" AcceptedAnswerId="3579" CreationDate="2014-04-26T02:24:15.903" Score="9" ViewCount="7470" Body="&lt;p&gt;Why are traditional style cockpits with gauges called 'steam cockpits'? Do the instruments actually run on steam?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="69" LastEditDate="2014-04-26T04:45:57.083" LastActivityDate="2017-07-10T19:44:04.163" Title="Where does the term 'steam cockpit' come from?" Tags="&lt;flight-instruments&gt;&lt;cockpit&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3578" PostTypeId="2" ParentId="3575" CreationDate="2014-04-26T03:37:01.710" Score="6" Body="&lt;p&gt;This is not answering your question directly but is relevant IMHO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also rules of thumb designed to prevent aircraft from arriving at the same place at the same altitude heading in opposite directions for example:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Follow line features (roads, rivers etc) by placing them on your left.&lt;/li&gt;&#xA;&lt;li&gt;The quadrantal rule for altitude selection (optional for VFR, but so is common sense). &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_level#Quadrantal_rule&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Flight_level#Quadrantal_rule&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Not arriving at common waypoints at &quot;obvious&quot; altitudes.  Use 1100 instead of 1000, 1450 instead of 1500 etc.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2014-06-05T07:43:59.987" LastActivityDate="2014-06-05T07:43:59.987" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3579" PostTypeId="2" ParentId="3577" CreationDate="2014-04-26T04:45:18.643" Score="12" Body="&lt;p&gt;Well, to answer your second question first: no.  No aircraft instruments actually run on steam.  There are lots of safety issues related to generating and using the steam on board an aircraft that are prohibitive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as why they are called &lt;strong&gt;&lt;em&gt;steam gauges&lt;/em&gt;&lt;/strong&gt;, take a look at one and compare it to a traditional flight instrument:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.trainweb.org/j.dimech/6167/pics/parts3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jJWHPm.jpg&quot; alt=&quot;Steam Gauge&quot;&gt;&lt;/a&gt; &lt;a href=&quot;http://media.chiefaircraft.com/media/catalog/product/cache/1/thumbnail/9df78eab33525d08d6e5fb8d27136e95/u/m/uma_16-310-120.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/81yaSm.jpg&quot; alt=&quot;Airspeed Indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are both round, both have a calibrated scale printed on  them, and both have a needle which points at the current value.  They actually look pretty similar!&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-26T04:45:18.643" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3580" PostTypeId="1" AcceptedAnswerId="3583" CreationDate="2014-04-26T11:13:31.053" Score="7" ViewCount="1376" Body="&lt;p&gt;I took a couple of pictures of various aircraft and I would like to know which aircraft I photographed. I have no idea, expect that all of them took off from &lt;a href=&quot;http://en.wikipedia.org/wiki/Z%C3%BCrich_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;ZRH&lt;/a&gt; and should be commercial airliners:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UcrXK.jpg&quot; alt=&quot;Pegasus aircraft above runway on takeoff&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f0nMJ.jpg&quot; alt=&quot;Swiss aircraft on approach to land&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BDB1k.jpg&quot; alt=&quot;Swiss aircraft on approach to land&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Cjzk.jpg&quot; alt=&quot;Swiss aircraft on approach to land&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qiIOy.jpg&quot; alt=&quot;Turkish aircraft on approach to land&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gktOi.jpg&quot; alt=&quot;Star Alliance aircraft on approach to land&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2210" LastEditorUserId="1696" LastEditDate="2015-04-23T14:40:42.350" LastActivityDate="2015-04-26T22:06:17.300" Title="Which aircraft did I photograph at ZRH?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3581" PostTypeId="1" CreationDate="2014-04-26T11:43:21.710" Score="10" ViewCount="1339" Body="&lt;p&gt;Small civilian mini-drones such as the DJI Phantom or professional surveying drones are becoming increasingly widespread, raising concerns about the potential collision/airprox with manned aircraft (especially GA where flight altitude is typically relatively low).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eRtwN.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have there been actual cases of collision and/or dangerous airprox reported so far? What were the consequences? &lt;/p&gt;&#xA;" OwnerUserId="94" LastEditorUserId="22726" LastEditDate="2019-02-21T04:21:30.330" LastActivityDate="2019-02-21T04:21:30.330" Title="Have there been any cases of collision/airprox of small drones with manned aircraft?" Tags="&lt;general-aviation&gt;&lt;unmanned-aerial-vehicle&gt;&lt;mid-air-collision&gt;" AnswerCount="6" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3582" PostTypeId="2" ParentId="3581" CreationDate="2014-04-26T11:43:21.710" Score="11" Body="&lt;p&gt;&lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS%3aHOMEPAGE%3a%3apc=HOME&quot; rel=&quot;noreferrer&quot;&gt;CASA&lt;/a&gt; (Australia's aviation authorities) has a report on an airprox between a crop duster and a surveying mini-drone:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.atsb.gov.au/media/4698157/ao-2013-167_final.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATSB incident report&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="94" LastEditorUserId="97" LastEditDate="2014-04-28T23:26:02.247" LastActivityDate="2014-04-28T23:26:02.247" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3583" PostTypeId="2" ParentId="3580" CreationDate="2014-04-26T12:51:52.907" Score="13" Body="&lt;p&gt;One of the simplest things you can do is to &lt;strong&gt;type in the registration into Google which will normally give you results of the type and history of the aircraft&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, many airlines don't operate too many types of aircraft so a &lt;strong&gt;quick look on Wikipedia and looking through 'fleet'&lt;/strong&gt; should show you which types it may be, from which elimination should be pretty quick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The registration is normally visible on the back of the fuselage and under the wing (D-ABEP on the rear fuselage below), and the last two letters are (often) printed on the aircraft 'forehead' above the cockpit windows, the top of the tail and the nose gear doors (EP on the nose gear doors below).&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gcOIs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gcOIs.jpg&quot; alt=&quot;Lufthansa&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aircraft from your photos: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 737&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320&lt;/li&gt;&#xA;&lt;li&gt;RJ85&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320&lt;/li&gt;&#xA;&lt;li&gt;Airbus A321&lt;/li&gt;&#xA;&lt;li&gt;Fokker 100&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1696" LastEditDate="2015-04-23T14:42:46.397" LastActivityDate="2015-04-23T14:42:46.397" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3584" PostTypeId="2" ParentId="3577" CreationDate="2014-04-26T13:21:38.920" Score="11" Body="&lt;p&gt;I never heard the term &quot;steam gauge&quot; until there were glass cockpits - but maybe that is just me.  A &quot;steam gauge airplane&quot; is a mildly derogative term to indicate that the plane has instruments that are old fashioned, borderline obsolete.  But they work just fine!  I fly a steam gauge airplane.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-04-26T13:21:38.920" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3585" PostTypeId="1" AcceptedAnswerId="3586" CreationDate="2014-04-26T14:27:13.033" Score="9" ViewCount="505" Body="&lt;p&gt;I know aircraft commonly have rotary actuators to extend and retract the flaps.  I am not sure how many but I think I read two per flap on a 747. My question is what is the result if one actuator fails? I don't know if more then one needs to fail in order for a flap not to extend or retract.  I am mostly wondering if could cause an aircraft turn-back because somebody told me it could. However that does not seem right to me.  I thought the flaps are extended before take-off so that worst case scenario prior to flight is a minor flight delay to replace it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose if it failed just prior to landing that would be the other scenario and am not sure what the worst impact on a pilots ability to land would be (assuming one failed unit would prevent a flap extension?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any experienced pilot probably knows more then I do and any insights are welcome.&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="2213" LastEditDate="2014-04-26T16:31:28.050" LastActivityDate="2014-04-26T16:31:28.050" Title="What is the impact of one trailing edge rotary actuator failing?" Tags="&lt;flight-controls&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3586" PostTypeId="2" ParentId="3585" CreationDate="2014-04-26T15:38:16.323" Score="5" Body="&lt;p&gt;The 747 has two motors per flap group.  The primary means of moving them is through a hydraulic motor, while the second motor is a backup electric motor which is only used if the primary doesn't work correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also two groups of flaps on each wing, and they are mechanically linked to the same flap group on the other wing so that they always extend at the same time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are correct about a failure on the ground.  The pilots would take the airplane back for maintenance before they departed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the unlikely event that both the primary and secondary motors failed, or if the flaps were to somehow become jammed and not extend once airborne, the flaps would not be able to do their job.  Since they wouldn't make the wing bigger or change it's shape to create more lift, the aircraft would be forced to land at a higher airspeed, which would cause it to use more runway.  This isn't a big deal if there is sufficient runway at their destination, but if not they would have to divert to a suitable airport.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-04-26T15:38:16.323" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3587" PostTypeId="2" ParentId="3581" CreationDate="2014-04-26T16:16:45.220" Score="-3" Body="&lt;p&gt;Within US airspace, no such thing has occurred. The FAA has regulations for UAV flight that keep them away from any potential collision in controlled airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Way back in 2011, &lt;a href=&quot;http://defensetech.org/2011/08/17/midair-collision-between-a-c-130-and-a-uav/&quot; rel=&quot;nofollow&quot;&gt;there was a collision&lt;/a&gt; between a military UAV and a C130 in Afghanistan.&lt;/p&gt;&#xA;" OwnerUserId="757" LastEditorUserId="97" LastEditDate="2014-04-28T23:26:22.640" LastActivityDate="2014-04-28T23:26:22.640" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3588" PostTypeId="2" ParentId="3580" CreationDate="2014-04-26T16:29:35.183" Score="2" Body="&lt;p&gt;The accepted answer has good advice. I would add that a quick and easy way to make a guess at the manufacturer is to look at the ends of the wings. Notice how in the first picture the wings &quot;bend up&quot; at the end. This is &lt;a href=&quot;http://www.b737.org.uk/winglets.htm&quot; rel=&quot;nofollow&quot;&gt;highly characteristic of Boeing 737s&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By contrast, the &quot;fence&quot; style wing tip that you see in three of your photos is highly characteristic of Airbus.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://en.wikipedia.org/wiki/Wingtip_device&quot; rel=&quot;nofollow&quot;&gt;Wikipedia's article&lt;/a&gt; on the matter for more information about why wings have unusual tips.&lt;/p&gt;&#xA;" OwnerUserId="1660" LastEditorUserId="97" LastEditDate="2015-04-26T22:06:17.300" LastActivityDate="2015-04-26T22:06:17.300" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3589" PostTypeId="1" AcceptedAnswerId="3591" CreationDate="2014-04-26T16:30:02.633" Score="14" ViewCount="14254" Body="&lt;p&gt;I've read about several aircraft having their rudder and brake pedals very close together. To me this seems confusing and prone to error. It looks easy to mistake the rudder / brake pedals and inadvertently press the wrong one when flying or taxiing the aircraft. Since these are fundamentally important controls, this could lead to disaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what is the advantage of keeping the rudder / brake pedals in this configuration? Are there any historical reasons for this design choice?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="167" LastEditDate="2014-12-10T12:32:21.847" LastActivityDate="2018-02-28T19:33:54.050" Title="What is the advantage of combining the rudder and brake pedals in aircraft?" Tags="&lt;flight-instruments&gt;&lt;taxiing&gt;&lt;braking&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3591" PostTypeId="2" ParentId="3589" CreationDate="2014-04-26T17:17:53.000" Score="31" Body="&lt;p&gt;All of the aircraft that I have ever seen have the rudder and braking functions combined into one set of two pedals.  To operate the rudder you press on the bottom part of the pedals, so that they slide back and forth on tracks, and to operate the brakes, you press the top part of the pedals so that they rotate towards the floor.  The left pedal operates the left wheel brake, and the right pedal operates the right brake, so you can use differential braking to turn the plane.  For rudder operation, the motion of the two pedals is locked together (i.e. press on the right pedal for right rudder, and the left pedal moves aft while the right pedal moves forward).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the two different motions (rotation for brakes versus sliding for rudder) there isn't a problem with hitting the brakes when you want rudder or vice versa.  Typical early training is to operate the rudder using your toes on the lower parts of the pedals, so and to only put your whole foot on the pedal to actuate the braking mechanism.&lt;/p&gt;&#xA;" OwnerUserId="2217" LastActivityDate="2014-04-26T17:17:53.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3592" PostTypeId="2" ParentId="3589" CreationDate="2014-04-26T17:30:42.573" Score="8" Body="&lt;p&gt;It is by design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane have &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_principal_axes&quot; rel=&quot;nofollow noreferrer&quot;&gt;three axes&lt;/a&gt; to move, unlike a car, thus more &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_surfaces&quot; rel=&quot;nofollow noreferrer&quot;&gt;controls&lt;/a&gt; should be provided to the pilot. As primates have two legs and two arms, the designers of airplanes put foot pedals to control the rudders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because Newton came up with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton.27s_first_law&quot; rel=&quot;nofollow noreferrer&quot;&gt;first law of motion&lt;/a&gt; before airplanes were built, we needed to have devise a way to stop airplanes, and hence brakes were invented. But unlike cars, where a foot or feet are used to apply the brakes, rudder pedals were already occupying that region. And hence airplane designers added brakes on top of the rudder pedals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like everything else, &lt;a href=&quot;https://en.wikipedia.org/wiki/Rudder#Aircraft_rudders&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; also evolved overtime.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The rudder's direction in aircraft since the &quot;Golden Age&quot; of flight&#xA;  between the two World Wars into the 21st century has been manipulated&#xA;  with the movement of a pair of foot pedals by the pilot, while during&#xA;  the pre-1919 era rudder control was most often operated with by a&#xA;  center-pivoted, solid &quot;rudder bar&quot; which usually had pedal and/or&#xA;  stirrup-like hardware on its ends to allow the pilot's feet to stay&#xA;  close to the ends of the bar's rear surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I disagree with the statement that combining them leads to any confusion. The rudder pedal/brake assembly is very easy to understand and master. The mistakes you make as a student are minimal and do not happen after a little training anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason for having rudder pedals on the floor is that in a coordinated turn, you might have to add slight rudder along with banking the airplane. As hands are used to bank, rudder pedals are controlled by feet. This situation is only applicable during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During &lt;strong&gt;flight&lt;/strong&gt;, brakes do not have any effect as they are applied on the main landing gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During &lt;strong&gt;taxiing&lt;/strong&gt;, when you press the rudder pedal (not applying brakes), on smaller airplanes, the nose wheel is turned.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="753" LastEditDate="2016-11-07T12:38:39.437" LastActivityDate="2016-11-07T12:38:39.437" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3593" PostTypeId="1" AcceptedAnswerId="3600" CreationDate="2014-04-26T17:57:17.247" Score="9" ViewCount="1825" Body="&lt;p&gt;I'm sitting behind an exit row (the exit row is row 12), but am still not sure why rows 10-11 are missing from this plane. Note the number goes from 9 to 12.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zAMJo.jpg&quot; alt=&quot;Row numbers skip from 9 to 12&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Why are the rows numbered this way? It's the same on both sides.&lt;/p&gt;&#xA;" OwnerUserId="1354" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-19T18:56:14.863" Title="Why are row numbers 10 and 11 skipped on Frontier's A-319?" Tags="&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3594" PostTypeId="2" ParentId="3589" CreationDate="2014-04-26T18:04:46.077" Score="14" Body="&lt;p&gt;Here are a few design constraints:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Unlike a car, there is sometimes the need to apply the left brake independently from the right brake.  (See &lt;a href=&quot;https://aviation.stackexchange.com/questions/1750/what-is-differential-braking/1759#1759&quot;&gt;What is differential braking?&lt;/a&gt; for more details and pictures.)&lt;/li&gt;&#xA;&lt;li&gt;There is a need to control the rudder, and you need to be able to move it either direction.&lt;/li&gt;&#xA;&lt;li&gt;The pilot needs to be able to make small and rapid adjustments to them both, in both directions.&lt;/li&gt;&#xA;&lt;li&gt;The pilot needs to be able to use both at the same time.&lt;/li&gt;&#xA;&lt;li&gt;The pilot needs to be able to use both while at the same time controlling pitch and bank.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Based on this, it's pretty easy to see that a push button, lever, or toggle switch somewhere wouldn't meet all of these requirements, especially if you need to use your hands (which are already occupied with the yoke) to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three axis of motion on an aircraft that the pilot can control directly, and with current designs, the flight controls move the aircraft in the same direction that they are moved:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Bank is controlled by turning the yoke left and right, which lowers the wing in the direction that you turn it.&lt;/li&gt;&#xA;&lt;li&gt;Pitch is controlled by pushing the yoke forward or pulling it back, making the nose raise or drop.&lt;/li&gt;&#xA;&lt;li&gt;Yaw is controlled by pushing the pedals in the direction that you want the nose to pivot.&lt;/li&gt;&#xA;&lt;li&gt;Since your feet are already on the rudder pedals and you need two brake pedals too (point one from above), they usually just put the brakes on the top of the rudder pedals so that they can be used at the same time.&lt;sup&gt;1&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; There are also hand brakes in some older aircraft that require you to use your hand.  This has been pretty much abandoned in favor of toe (or heel) brakes since it did not allow for differential braking.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-04-26T18:04:46.077" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3595" PostTypeId="1" CreationDate="2014-04-26T18:25:05.830" Score="5" ViewCount="1387" Body="&lt;p&gt;Preflight checklists often contain the item&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight controls: Free and correct&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, if the rudder is tied to nose-wheel steering, is it even possible to check if the rudder is correctly connected (unless have a rear window and can see the rudder during taxi)?&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-04-28T19:16:21.290" Title="How do you check the correct operation of the rudder when it's tied to the nose wheel?" Tags="&lt;flight-controls&gt;&lt;preflight&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3596" PostTypeId="2" ParentId="3595" CreationDate="2014-04-26T19:10:38.033" Score="1" Body="&lt;p&gt;Every plane I've ever flown with a linked nose gear, the rudder will make noise when it hits the stops. On top of that, the nose gear linkage is disconnected when you use more than a certain degree of deflection. If you push the pedals past that point and feel resistance, your rudder is working.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-04-26T19:10:38.033" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3597" PostTypeId="2" ParentId="3595" CreationDate="2014-04-26T20:39:07.917" Score="8" Body="&lt;p&gt;Every small airplane that I've flown that uses the rudder pedals for nose wheel steering uses bungee cords or springs so that they will stretch when pushing the pedals without the aircraft moving.  This allows the pedals to move without requiring the nose wheel to do so as well, and you can check them in the normal manner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger airplanes that use the rudder pedals for nose wheel steering have a method of turning the nose wheel steering on and off, so the check could be done before the steering is engaged.  That being said, most larger aircraft do the control check during the taxi (that's when most airliners are doing it) and there is nobody out there to make sure that the rudder is actually moving the correct direction.  In my airplane, the response for the flight controls is &quot;free and self-centering&quot; (since we have hydraulic flight controls) and we don't verify the actual direction of rudder movement.  That's a maintenance function.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-26T23:47:25.223" LastActivityDate="2014-04-26T23:47:25.223" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3599" PostTypeId="2" ParentId="3471" CreationDate="2014-04-27T06:02:13.903" Score="4" Body="&lt;p&gt;I am quite sure that the systems that provide audio warnings for commercial aircraft, such as enhanced ground proximity warning computers, provide &lt;strong&gt;English Only&lt;/strong&gt;. I am pretty sure because on the wiring diagrams there are no kind of dip-switches for language selection and for loadable software it is tightly regulated without any 'language selection' options.  One could imagine that separate part numbers are created for different languages but I know this is also not case case as international carriers share/pool spare black boxes. Basically aviation language is English.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also see &lt;strong&gt;no future provision for other languages&lt;/strong&gt; as it was only recently in 2008 that ICAO mandated English for all international flights (Amendment 164 to Annex 1 ). Under this ruling Air Traffic Controllers and Flight Crew Members engaged in or in contact with international flights must be proficient in the English language as a general spoken medium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding Airbus (and the love that the French have of their language) we might do well to know that actual official language of the Airbus company is surprisingly to some 'English.'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course I can't comment on military applications much. Actually, I was previously slightly involved in supporting a military aircraft and from what I can tell they use many modified versions of the same components commercial aircraft do. At least for US, British or French allies, who are allowed to import the technology. However, they are modified directly by the customer to be more security tolerant. For example, a military aircraft might not be transmitting its location around the globe unless the receiver has a decoding ability to a secure military key. So even in the small exposure I have encountered with military applications, I have not encountered or heard of 'language options.'  This is not to say that some Chinese or Russian might be heard in some remote aviation system somewhere but that if it does outside their aerospace industries it must be rare and still a 'one language' only feature. &lt;strong&gt;Possibly there are missile guidance systems in Russian, Chinese, or Korean but certainly not in international commercial aviation.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2213" LastActivityDate="2014-04-27T06:02:13.903" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3600" PostTypeId="2" ParentId="3593" CreationDate="2014-04-27T07:39:13.340" Score="18" Body="&lt;p&gt;Airline row numbering has more to do with fleet consistency than sequential numbering in one airplane type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Head over to &lt;a href=&quot;http://seatguru.com&quot;&gt;SeatGuru&lt;/a&gt; and look up &lt;em&gt;Frontier&lt;/em&gt;. They fly 3 types of mid-size narrowbody - A319, A320, Embraer E190 - and not surprisingly row 12 is an exit row in each one. The E190 and A319 don't have row 11, only the A319 is missing row 10. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the same reason 2+2 seating skips seats B and E ( AC DF ), where 3+3 seating goes all the way across ( ABC DEF ). Widebody aircraft have a different sequence because it doesn't need to match - the same cabin crew will rarely work both major classes and they don't tend to run regional airlines on widebody (long-haul) routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at Air Canada's fleet - row 18 is the beginning of economy and an exit row in almost the entire widebody fleet (the exception is probably historical).&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="247" LastEditDate="2014-04-28T05:07:45.983" LastActivityDate="2014-04-28T05:07:45.983" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3601" PostTypeId="2" ParentId="2530" CreationDate="2014-04-27T18:41:04.630" Score="-2" Body="&lt;p&gt;Sound waves travel through water for incredible distances. For example world war two mines were still to be heard many hundreds of miles from the original source of the explosion and more interesting, they were heard several years after the event that caused the sound wave, so it is probable that it was the sound waves of pings rather than the actual ping that has been detected. &lt;/p&gt;&#xA;" OwnerUserId="2224" LastActivityDate="2014-04-27T18:41:04.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3604" PostTypeId="5" CreationDate="2014-04-27T22:23:27.800" Score="0" Body="&lt;p&gt;See also: &lt;a href=&quot;http://meta.aviation.stackexchange.com/questions/249/can-we-have-identify-that-airplane-questions&quot;&gt;Can we have &amp;quot;identify that airplane&amp;quot; questions?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-04-27T22:23:27.800" LastActivityDate="2014-04-27T22:23:27.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3605" PostTypeId="4" CreationDate="2014-04-27T22:23:27.800" Score="0" Body="For questions seeking to identify an aircraft, e.g. by description or photograph." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-05-02T22:22:15.213" LastActivityDate="2014-05-02T22:22:15.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3607" PostTypeId="2" ParentId="1904" CreationDate="2014-04-27T23:54:47.373" Score="15" Body="&lt;p&gt;While turning the nose gear is the primary means of turning while taxiing, differential thrust can be used when necessary. Offhand I can think of three instances where differential thrust should be used on an airplane such as the 747:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If for whatever reason you are taxiing very slowly, and you're on narrow taxiways and need to make a 90 degree turn, you'll need differential thrust to keep the airplane from stopping in the turn.&lt;/li&gt;&#xA;&lt;li&gt;If your center of gravity is near the aft limit, there won't be much weight on the nose gear, and it might start skidding when you try to turn significantly without differential power.&lt;/li&gt;&#xA;&lt;li&gt;If the asphalt is hot and/or you're on reverted rubber, the nose gear won't have a lot of traction, and you really need to think about using differential power. I almost slid off a taxiway at Jeddah one day in such a situation even though my taxi speed was only around 8 knots. A general rule of thumb for the 747 in making 90 degree turns was to have your taxi speed down to 10 knots or less, otherwise the nose wheels might just skid.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-04-27T23:54:47.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3608" PostTypeId="1" AcceptedAnswerId="15486" CreationDate="2014-04-28T10:59:06.533" Score="52" ViewCount="32505" Body="&lt;p&gt;Generally speaking, What programming language is used in aviation for (ATC Radio, Radar, ILS, Auto-pilot and on-board avionics)?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there a standard enforced by ICAO?&lt;/li&gt;&#xA;&lt;li&gt;Does every plane manufacturer use the programming language they like as long as it's reliable and it goes through testing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I remember watching a documentary on YouTube last year about aviation and it said something about the EU, after WWII, started making standards for aviation systems inside Europe.&#xA;I will link the video if I can find it&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="19" LastEditDate="2015-06-16T12:28:18.057" LastActivityDate="2019-04-06T23:36:02.867" Title="What programming languages are used for equipment onboard aircraft?" Tags="&lt;avionics&gt;&lt;icao-sarps&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="3609" PostTypeId="2" ParentId="3608" CreationDate="2014-04-28T11:12:42.857" Score="15" Body="&lt;p&gt;As far as I know, there is no directive on which language to use. You have &lt;a href=&quot;https://aviation.stackexchange.com/questions/3405/is-there-any-u-s-faa-regulation-that-could-apply-for-aviation-software/3412#3412&quot;&gt;guidelines&lt;/a&gt; on how to test and certify software, but as far as these guidelines are concerned, no language is preferred, it is a design choice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of today, in my (limited) experience as an engineer/programmer, I have mostly seen that non object oriented languages are preferred, since they reduce the amount of testing required. Usual arguments I have encountered primarily concern explicit memory management in often resource-limited environments.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-04-29T13:25:25.647" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3610" PostTypeId="1" AcceptedAnswerId="3624" CreationDate="2014-04-28T13:05:36.240" Score="14" ViewCount="7050" Body="&lt;p&gt;We know from other questions and answers that airplanes and gliders in particular can have their performance described in terms of &lt;a href=&quot;https://aviation.stackexchange.com/a/698/1467&quot;&gt;glide polar&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/2999/how-far-can-airplanes-glide&quot;&gt;Lift-to-Drag ratio&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it appears from the images in the first linked answer (included below), the two are connected to each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Despite my research I couldn't find a source on how to derive one curve given the other (the polar given the ratio or the ratio given the polar). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to do so? I have heard from friends that are glider pilots that the &lt;code&gt;glide polar&lt;/code&gt; curve can be described as a parabola, but I haven't found any reference.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;L/D ratio&#xA;&lt;img src=&quot;https://i.stack.imgur.com/DUyHv.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glide Polar&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ZFmN6.jpg&quot; alt=&quot;&quot;&gt;&#xA;&lt;sup&gt;&lt;em&gt;Images from &lt;a href=&quot;https://aviation.stackexchange.com/a/698/1467&quot;&gt;this question&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-07T06:15:26.967" Title="How are the glide polar and L/D ratio charts related?" Tags="&lt;aerodynamics&gt;&lt;glider&gt;&lt;glide-ratio&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3611" PostTypeId="2" ParentId="3610" CreationDate="2014-04-28T13:38:38.360" Score="8" Body="&lt;p&gt;Let's look at what exactly is shown by each curve:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The glide ratio curve plots glide ratio (horizontal distance divided by vertical distance) against airspeed.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_curve_%28aviation%29&quot;&gt;polar curve&lt;/a&gt; plots vertical speed against airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;i&gt;x&lt;/i&gt; axis (airspeed) is the same for both plots, but the &lt;i&gt;y&lt;/i&gt; axis is different. To convert one curve to the other, we need to convert glide ratio to vertical speed and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note: I'm going to make a slight simplification here and assume that &lt;em&gt;airspeed&lt;/em&gt; is the same as &lt;em&gt;horizontal speed&lt;/em&gt;. This is not true when climbing or descending. A more accurate answer will require some trigonometry to calculate horizontal speed from airspeed. But the error introduced by this simplification is very small.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Vertical speed is simply airspeed times glide ratio.&lt;/li&gt;&#xA;&lt;li&gt;Glide ratio is simply vertical speed divided by airspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, to make one curve out of the other:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To plot the polar curve, take a glide ratio curve and multiply it by the &lt;i&gt;x&lt;/i&gt; coordinate (thus converting glide ratios to vertical speeds). Conceptually, as you travel outward on the &lt;i&gt;x&lt;/i&gt; axis, you are &lt;i&gt;magnifying&lt;/i&gt; the curve by &lt;i&gt;x&lt;/i&gt;.&lt;/li&gt;&#xA;&lt;li&gt;To plot a glide ratio curve, take the polar curve and divide it by the &lt;i&gt;x&lt;/i&gt; coordinate (thus converting vertical speeds to glide ratios).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You mentioned parabolas. The polar curve is a &quot;parabola&quot; only in the vaguest sense that it is &lt;em&gt;shaped like&lt;/em&gt; a parabola. It is not a precise mathematical parabola. Its exact shape is determined by &lt;em&gt;extremely&lt;/em&gt; complicated aerodynamic factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this being said, if your airplane has a published polar curve, use it, instead of deriving your own. Its values were measured and verified during flight test and you're better off using those than something you produced yourself using other data.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-28T14:03:44.833" LastActivityDate="2014-04-28T14:03:44.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3612" PostTypeId="1" AcceptedAnswerId="3623" CreationDate="2014-04-28T13:46:52.123" Score="31" ViewCount="18731" Body="&lt;p&gt;I have heard that wind affects the actual airspeed that I should fly for maximum range in an aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that wind will not affect the airspeed that I should fly if I am looking for maximum endurance, but what about maximum range? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How (and how much) should airspeed be adjusted for wind in order to get maximum range? &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-04-28T13:55:05.037" LastActivityDate="2018-09-30T16:14:03.727" Title="How does wind affect the airspeed that I should fly for maximum range in an airplane?" Tags="&lt;aircraft-performance&gt;&lt;wind&gt;&lt;range&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3613" PostTypeId="2" ParentId="3559" CreationDate="2014-04-28T16:42:14.337" Score="0" Body="&lt;p&gt;$0.02 to add to all that. The question can be extended a little and one could ask 'why fly ifr on beautiful clear day'. Added safety. For a new instrument pilot it would still be a good practice to operate in the ifr system even if you can't log the flight for currency purposes.&lt;/p&gt;&#xA;" OwnerUserId="2167" LastActivityDate="2014-04-28T16:42:14.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3614" PostTypeId="1" AcceptedAnswerId="3615" CreationDate="2014-04-28T17:23:09.947" Score="25" ViewCount="5311" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/3559/reasons-for-using-an-instrument-approach-on-a-clear-day&quot;&gt;another question&lt;/a&gt; earlier when I noticed a story about a 737-700 that landed at &lt;a href=&quot;http://en.wikipedia.org/wiki/M._Graham_Clark_Downtown_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;M. Graham Clark Downtown Airport&lt;/a&gt; in downtown Branson Missouri.  The runway is only 3738 ft, long, which is a bit short for that particular kind of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently the pilots set the aircraft down hard and immediately did everything in their power to bring the craft to a halt, &lt;a href=&quot;http://edition.cnn.com/2014/01/13/travel/southwest-plane-wrong-airport/&quot; rel=&quot;nofollow noreferrer&quot;&gt;stopping about 500ft short&lt;/a&gt; of the far end of the runway (which, btw, ends in a cliff.  Just to heighten the suspense).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure they had their reason, so I'm not going to question them.  I just wanted to use it as a set up for this question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you accidentally touch down on a runway that is borderline long enough to stop your aircraft on, how would you determine if you wanted to either stop or just do a touch and go?  Is it too late once you've already touched the ground?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-26T17:08:12.473" Title="What to do when you accidentally land on a runway thats borderline long enough to land on?" Tags="&lt;safety&gt;&lt;landing&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3615" PostTypeId="2" ParentId="3614" CreationDate="2014-04-28T18:24:37.470" Score="31" Body="&lt;p&gt;In terms of safety, the key mistake was made as soon as the pilot made the decision to land on that runway. The corrective emphasis should be on determining why this mistake was made and taking whatever steps are necessary to prevent that mistake in the future. Especially in transport category airplanes, the crew should always calculate the required landing/rollout distance for the current landing weight, wind, atmospheric (temperature/pressure) and runway surface conditions, and this should be compared against the approach plate / airport diagram / A/FD. In most transport category airplanes this can all be computed by the FMS and it is standard procedure to do this on every single flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question of what to do after the key mistake is still valid, though. I would say it depends on when the pilot recognizes that the runway is too short.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If recognized on approach, a simple go around is clearly called for and perfectly safe.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Once the wheels touch the ground, the decision gets a lot more complicated. The pilot must choose whether to reject the landing or commit to it. If you recognize it as soon as you touch down, you would probably be able to apply takeoff power and get airborne again safely. Once you've started to brake and decelerate, there will quickly come a point-of-no-return. Since you're starting at high speed, you're using up a &lt;em&gt;lot&lt;/em&gt; of runway early in the landing rollout. Also note that in many airplanes it can take a significant amount of time to retract spoilers, stow thrust reversers, and spool the engines back up to takeoff thrust. You'll be consuming a lot of runway during this time. (At a constant 120 knots, you'll use up 2,000 feet of runway in just 10 seconds.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In my opinion it's far better to commit to a landing. If I'm going to overrun the runway, I'd rather it happen at low speed. If you try to take off again and don't make it, your overrun will be at much higher speed, and destructive energy in a crash is proportional to the &lt;em&gt;square&lt;/em&gt; of your ground speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there's a gray area... you &lt;em&gt;could&lt;/em&gt; attempt to take off again if you were &lt;em&gt;dead certain&lt;/em&gt; you were going to make it. Otherwise, it's most likely best to &quot;cut your losses&quot; and get the airplane as slow as possible when you run out of runway, in order to minimize damage &amp;amp; injury. If you can get it down to, say, 30 or 40 knots, you're likely to escape without any serious injuries (the plane may take a bit of a beating, though, depending on what's beyond the end of the runway). If you do it at 120 knots, all bets are off. And you did mention a specific runway with a cliff at the end; obviously that would have to factor into the decision-making process. It may be that you simply realized your mistake &lt;em&gt;too late&lt;/em&gt; and there is &lt;em&gt;nothing&lt;/em&gt; you can do about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This leads me back to the original point, which is that the key mistake was made as soon as the pilot decided to set up an approach to that runway. The best bet is to make sure that never happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: After reading about the specific incident you referred to, it seems that the pilots simply mistook the airport itself for a different one with a longer runway. So it's not necessarily that they failed to calculate their required landing distance; rather they just landed at the wrong place. This is a different, but equally bad (or worse) mistake, discussed to some extent in the comments below.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-29T18:08:37.710" LastActivityDate="2014-04-29T18:08:37.710" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="3616" PostTypeId="2" ParentId="3612" CreationDate="2014-04-28T19:04:36.283" Score="0" Body="&lt;p&gt;Airspeed is your speed through an air mass, wind speed or direction will not change your airspeed. What wind direction changes is your ground speed, which is the speed of the aircraft over the surface of the earth. A headwind component reduces your ground speed, while a tailwind increases it. What I think you are asking is how you change your airspeed to best use fuel depending on whether you have a headwind or tailwind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general answer to this is that if you have a headwind you would increase your airspeed, and with a tailwind reduce it. If you have a headwind you will take longer to get where you are going, so increasing airspeed will get you there faster and you will use less fuel. A tailwind gets you there faster so you can reduce your airspeed and therefore fuel burn and still get there in the same amount of time as you would if you were in still air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice whether you do this depends on how much of a headwind/tailwind component you have, and what your burn rates are at different airspeeds. Aircraft have a speed/drag curve, at some point the energy you add to go faster just ends up being wasted. You can also get behind the drag curve, flying too slow to be efficient. Adding a bit more speed may make sense, adding a load more speed will likely end up in using more fuel without much result. The opposite is also true, you can end up getting too slow and draggy, burning more fuel. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-04-28T19:04:36.283" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3617" PostTypeId="2" ParentId="3595" CreationDate="2014-04-28T19:16:21.290" Score="1" Body="&lt;p&gt;It depends on the construction of the aircraft, if you have a linked nosewheel you generally cannot check this in preflight. Once you start up and are taxiing you would have a look out the back and check. When turning left I check compass, di, turn/bank all showing the correct response and rudder left. Vice versa for turning right. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-04-28T19:16:21.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3618" PostTypeId="2" ParentId="3614" CreationDate="2014-04-28T19:31:36.383" Score="11" Body="&lt;p&gt;If you accidentally land on a runway chances are you have no idea whether it is long enough or not for either a touch and go or a landing, and &lt;strong&gt;you aren't going to be able to figure it out in the time you've got either&lt;/strong&gt;. For me the answer of what to do depends on what you are flying. &#xA;If you have a high thrust to weight ratio the safer option may be to set maximum power and try to climb out of it, providing there's no obvious clearance issues. So if I'm in a P-51 I throttle up and set a maximum climb rate speed. Otherwise the best option would be to treat it as a short field scenario and use every means at disposal to remove as much energy from the aircraft as quickly as possible, while warning passengers to brace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you survive, go to a mechanic in the local FBO and ask him/her to kick you in the butt as hard as they can for being an idiot. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="718" LastEditDate="2014-04-29T15:47:40.753" LastActivityDate="2014-04-29T15:47:40.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3619" PostTypeId="1" AcceptedAnswerId="3621" CreationDate="2014-04-28T19:34:13.687" Score="5" ViewCount="4175" Body="&lt;p&gt;Looking at the paths of the same flight on two different days, I noticed they flew very different paths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://flightaware.com/live/flight/ETD101/history/20140426/0630Z/OMAA/KJFK&quot; rel=&quot;nofollow noreferrer&quot;&gt;Short Path&lt;/a&gt;:&lt;/strong&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;YAY N184B TOPPS ENE PARCH1&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z2jQW.gif&quot; alt=&quot;Short Path&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://flightaware.com/live/flight/ETD101/history/20140415/0630Z/OMAA/KJFK&quot; rel=&quot;nofollow noreferrer&quot;&gt;Long Path&lt;/a&gt;:&lt;/strong&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;NIBAX G462 TUMAK UL602 ORSOL UL602 DAVUS UL602 TASMI UL602 ITBIT UM860 KABAN UT334&#xA;INB UL852 UDROS L621 REVDA UP193 CND UP193 KARIL UL624 LABUK UY444 ELMEK UL726 OKG&#xA;UL984 NOSPA TOLVU UN857 GIMER UT300 EVX UT176 LGL UN491 KOKOS UN585 REGHI UN480 &#xA;ETIKI NATD DOVEY LACKS BERGH L454 OWENZ CAMRN CAMRN4&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xP2ZF.gif&quot; alt=&quot;Long Path&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I asked a &lt;a href=&quot;https://aviation.stackexchange.com/questions/446/different-flight-paths-for-same-journey&quot;&gt;similar question&lt;/a&gt; in the past. This is what I want to know:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are the reasons which can cause a commercial flight to change its path mid-route?&lt;/li&gt;&#xA;&lt;li&gt;How it is planed and executed?&lt;/li&gt;&#xA;&lt;li&gt;I am sure the captain is the final authority on this, but who else is informed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;em&gt;Route Source: &lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightAware&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;P.S.:&lt;/em&gt; I could not understand the routes at all.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-04-28T22:02:51.623" Title="Can/do commercial flights change their flight path during flight?" Tags="&lt;flight-planning&gt;&lt;international&gt;&lt;oceanic&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3620" PostTypeId="2" ParentId="2903" CreationDate="2014-04-28T20:16:08.393" Score="10" Body="&lt;p&gt;The stall Angle of Attack (AoA) is not fixed, but increases with pitch rate and - to a lesser extent - with the Reynolds Number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a wing stalls, the boundary layer in the rear part of a wing stops and even reverses it's flow direction, causing &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=8%7C0.1463#5055&quot;&gt;separation&lt;/a&gt;. For the outer air flow, this looks as if the wing has grown thicker there and has a smaller AoA than before, without separation. This causes the lift loss of a stalled wing. The &quot;history&quot; of the local boundary layer influences this - if it has seen a high acceleration around the nose of the airfoil, it has to perform a steep deceleration over the remainder of the wing. Friction has already reduced the energy of this boundary layer, and the steep deceleration ends in separation further downstream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the stall AoA is approached rapidly, the boundary layer on the rear wing has still the characteristics which go with the low AoA that prevailed when that parcel of air flowed around the wing's nose. Therefore, it has more energy left and is less prone to separation. The effect is an increase in the stall AoA with pitch rate, to a point where the total lift of the wing is 50% more than that at the stationary AoA at the same speed. Of course, this is a dynamic stall with a load factor much higher than 1. For more details, I refer you to &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a380413.pdf&quot; rel=&quot;noreferrer&quot;&gt;NACA TN 2525&lt;/a&gt; from 1951. No price for guessing which airplane was used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip side, the lift drops much more than in a static ( = slow pitch rate) stall. A docile stall behavior can now become abrupt! Another consequence of this lift overshoot is the possibility of a hysteresis loop, especially in helicopter, propeller and turbine blades where strong and cyclic changes in AoA are possible. This is called lift flutter and causes high mechanical stresses and vibration. See &lt;a href=&quot;https://de.scribd.com/doc/36093604/Fluid-Dynamic-Lift-1985-Hoerner&quot; rel=&quot;noreferrer&quot;&gt;Sighard Hörner's &quot;Fluid Dynamic Lift&quot;&lt;/a&gt;, page 4-24 and 25 for more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Reynolds number effect is less pronounced, but still gives an increase in stall c&lt;span class=&quot;math-container&quot;&gt;$_{l max}$&lt;/span&gt; of 15 - 25% between &lt;span class=&quot;math-container&quot;&gt;$Re = 10^6$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$Re = 5\cdot 10^6$&lt;/span&gt;. Details depend on the particular airfoil. Abbott-Doenhoff or the Wortmann catalog have lots of data on this.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-03-29T17:19:27.137" LastActivityDate="2019-03-29T17:19:27.137" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="3621" PostTypeId="2" ParentId="3619" CreationDate="2014-04-28T20:17:11.167" Score="10" Body="&lt;p&gt;A flight &lt;em&gt;plan&lt;/em&gt; is just that, a &lt;em&gt;plan&lt;/em&gt;.  A flight can deviate from its cleared route for many reasons, the most common of which are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Weather&lt;/li&gt;&#xA;&lt;li&gt;Traffic&lt;/li&gt;&#xA;&lt;li&gt;Shortcuts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weather&lt;/strong&gt; reroutes are often initiated by the crew.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Center, N12345 request 15 right for weather&lt;br&gt;&#xA;  N12345 15 right approved for 100 nm, report direct XYZ.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Or they can be initiated by ATC&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N12345, Atlanta, your arrival into EWR is in perpetual holding, I can re-route you over PA or NY or do you need to divert? state intentions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Large scale re-routing for weather will occur when an organized line of convection impacts a major route.  Even a short deviation for weather may result in an amended route if the controller has an alternate clearance he can put you on that works for you (being on a clearance and on-route is slightly less work for a controller than being on a carte-blanche deviation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Traffic&lt;/strong&gt; conflicts are usually short term vectors, but if you have an aircraft slowly overtaking you, you may be moved to a parallel route or have you altitude changed.  These, like the weather example above, would result in amended clearances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Shortcuts&lt;/strong&gt; are often requested to cut corners or try to make up some time lost in a long taxi on the ground.  These are usually crew initiated, but sometimes ATC will solicit them.  Regardless of what route is submitted in a flight plan, ATC will generally clear you via a preferred routing.  These routes aren't always the shortest distance between a departure and arrival and this is where shortcuts can be requested.  Usually this just means skipping a fix or getting direct routing to a later fix in your clearance.  The availability of shortcuts is a function of traffic, time of day, agreements between ATC sectors, what region you are in and what altitude you are at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are on international flights, another issue you may run into is political and could result in some or all aircraft being routed to avoid certain airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, your dispatcher may re-route you and ATC will clear you along a new route.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In all cases, whether deviation is pilot or controller initiated, both parties are in sync with what the airplane is doing, which will either be a vector or a new clearance.  Your dispatcher will be notified of this change automatically via their dispatch software (which is likely fed data from both ACARS and the FAA).&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-04-28T22:02:51.623" LastActivityDate="2014-04-28T22:02:51.623" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3622" PostTypeId="1" AcceptedAnswerId="9903" CreationDate="2014-04-28T21:23:51.533" Score="9" ViewCount="1816" Body="&lt;p&gt;I'm a frequent subscriber of airport messaging services where you get notified of check-in queue times, delays in takeoff, ETA + 10 minutes, landed timestamp, baggage claim time and these kinds of information, but not life-dependent messages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if something bad happens I assume I won't get a &quot;Flight X crashed and burned&quot; message on my cell, but most likely a &quot;Contact the airline at 555-1212 for more information&quot; or something similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the standard operating procedure in these cases?&lt;/p&gt;&#xA;" OwnerDisplayName="user2230" LastEditorUserId="64" LastEditDate="2014-04-29T21:04:52.867" LastActivityDate="2014-11-26T12:04:49.143" Title="How do airlines handle communication/notification after an accident?" Tags="&lt;emergency&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3623" PostTypeId="2" ParentId="3612" CreationDate="2014-04-28T21:32:18.323" Score="20" Body="&lt;p&gt;My answer was rather concise first, and I got the impression that I need to elaborate the question first. The question is about the best airspeed for maximum range. With wind. Best range means you cover the most distance while the wind is carrying the plane with it. If you have a headwind, the longer you stay aloft, the more you are carried back, so you better hurry up. With a tailwind, it helps to slow down because now the wind is helping you to cover even more distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But how much? We need to pick that particular speed where the change in fuel consumption just balances the change in speed over ground. I always found that easier to explain with gliders, and there you can really observe which polar point is best. Just picture yourself as an observer on the ground who sees the plane fly by in the distance. If you plot a line with the combination of positions and altitude, there must be one flight speed that produces a line where the flight path angle is the shallowest. This is the desired optimum. That has only little to do with optimum L/D - this is just one other point you can find with a sink speed polar. And it happens to be the point for best glide in still air. But there is so much more that humble polar will tell you, if you look at it the right way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With powered aircraft you need to pick the polar point where your fuel flow is lowest for the given speed over ground. Basically, you fly like the glider and add enough power to stay at the same altitude. That is all the difference. User2168 has answered that part already with a graphical solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, now back to gliders. Please look at the plot below which shows airspeed on the X axis and sink speed on the Y axis.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/E5kUv.png&quot; alt=&quot;Optimum Speed for Best Range&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution is graphical: You start on the X-axis at the point which corresponds to the wind speed and put a tangent on the sink speed graph. Where the tangent touches the sink polar (blue line), the plane flies at the best L/D for that given wind speed. Move the starting point to positive speeds for headwind and to negative speeds (not shown here) for tailwind. If the term &quot;best L/D&quot; is already reserved in your mind, please read this as the &quot;best polar point&quot;. It is really the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since User2168 has beaten me to the graphical solution, I will add an analytical solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For powered flight things become more tricky, because thrust changes with speed. To simplify things, we can say that thrust changes over speed in proportion to the expression $v^{n_v}$ where $n_v$ is a constant which depends on engine type. Piston aircraft have constant power output, and thrust is inverse with speed over the speed range of acceptable propeller efficiencies, hence $n_v$ becomes -1 for piston aircraft. Turboprops make some use of ram pressure, so they profit a little from flying faster, but not much. Their $n_v$ is -0.8 to -0.6. Turbofans are better in utilizing ram pressure, and their $n_v$ is -0.5 to -0.2. The higher the bypass ratio, the more negative their $n_v$ becomes. Jets (think J-79 or even the old Jumo-004) have constant thrust over speed, at least in subsonic flow. Their $n_v$ is approximately 0. Positive values of $n_v$ can be found with ramjets - they develop more thrust the faster they move through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for fuel flow: This goes up and down with the power output of the engine. Again a simplification, but it helps to get to grips with the problem and gives useful results. This lets us re-formulate the problem as: At what airspeed do I have the best ratio between power and ground speed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mathematically, we want to fly with $\frac{P}{v_w+v}$ at the lowest possible value. $P$ is the power, $v_w$ is the wind speed and $v$ the airspeed. To express the thrust behavior over speed, I break P up into a product of a constant $K_S$, the throttle setting $\delta$ and the speed like this: $K_S\cdot\delta\cdot v\cdot v^{n_v}$. Here is the general solution, pasted as a PNG to save me all the typing in the editor:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/G5UR8.png&quot; alt=&quot;formulas&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that implicitly the lift coefficient is on both sides of the equation. To solve it, you need to do it recursively, until speed and lift coefficient match. I took this form because of the similarity to the general form at still wind which can be found in many performance books. This here I didn't find anywhere, and it took me a while to figure it out. Thank you, Lnafziger, for the excellent question! It gave me a chance to learn something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have put the results into a plot. In order to eliminate the aircraft-specific parameters, it shows the ratio of $c_L$ with wind over $c_L$ without wind. The plot is metric, but will work for all units if you use the same units for wind speed and air speed.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Cp0CY.png&quot; alt=&quot;best cl over speed&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give an example for the application of the correction factor: If you are flying in a 20 m/s headwind and your best range speed at still wind is 50 m/s (approx 97 kts), the $c_L$ needs to be 70% of the $c_L$ at still wind for piston-powered aircraft. This makes your corrected airspeed 60 m/s (v is proportional to $\sqrt{c_L}$), and now the recursive nature of the formula rears its ugly head. At 60 m/s, the correction is only 77.5%, so we need to do a few loops until we arrive at a point where the airspeed and the correction factor match. In this example, this would be 57 m/s or 110 kts in case of a piston-powered aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-07-19T19:34:41.477" LastActivityDate="2014-07-19T19:34:41.477" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3624" PostTypeId="2" ParentId="3610" CreationDate="2014-04-28T22:14:57.010" Score="7" Body="&lt;p&gt;The curves in the top chart are gradients. The bottom chart lists these gradients over flight speed. Say you have in the top chart the y-value L/D = 36 at an x-value of 36 m/s, you do this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TxMyP.png&quot; alt=&quot;Glide polar plot with example for glide ratio calculation&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every point in the bottom diagram can be constructed by drawing a line (red in the example above) from the origin of the coordinate system with the gradient given by the y-value. Where it reaches the corresponding x-value, you get one point of the blue curve in the bottom diagram. You will need to do this for many x-y pairs to get a full polar curve. I used m/s on both axes to make the procedure more transparent.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The parabola is not so bad for a first-order approximation. If we assume that drag is composed of friction drag and induced drag, we can express this as&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$c_D = c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $c_D$ is the drag coefficient, $c_{D0}$ is the drag coefficient at zero lift (caused mainly by friction drag), $c_L$ is the lift coefficient, $\pi$ is 3.14159…, AR is the aspect ratio of the wing and $\epsilon$ is the Oswald factor (which mainly describes how well the lift is distributed over the span of the wing. Use 0.98 for gliders and 0.7 - 0.8 for other aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you plot this, it is indeed a parabola, and it fits with measured drag polars quite well. The model breaks down beyond the upper and lower stall angles of attack when flow separation causes the lift slope to become nonlinear. If you want to re-create the DG plots in your question, you should use the equation above and keep $c_L$ constant at the $c_{L max}$ for plotting, but calculate $c_D$ with the linearly increasing $c_L$, so the induced drag continues to grow even when the wing stalls. This gives a very good approximation even beyond the stall angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otto Lilienthal was the first pioneer of manned flight who measured the lift and drag of airfoils and wings, and he published the results in a polar diagram. That is why we still call these plots polars today, even when we use Carthesian coordinate systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To arrive at speeds, you need to add wing loading $\frac{W}{S} = \frac{m\cdot g}{S}$ and air density $\rho$ like this:&#xA;$$v = \sqrt{\frac{2\cdot m\cdot g}{\rho\cdot S\cdot c_L}}$$&#xA;For the sink speed, things get much easier if we assume that the cosine of the glide path angle $\gamma$ is 1. Then we can write:&#xA;$$v_z = v\cdot \frac{c_{D0}}{c_L} + v\cdot \frac{c_L}{\pi\cdot AR\cdot\epsilon}$$&#xA;Tabulate $c_L$ in your favorite spreadsheet, compute the speeds like that and plot the result. Make sure you restrict $c_L$ for plotting as explained above! Let me know how close the result is.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:15:26.967" LastActivityDate="2015-05-07T06:15:26.967" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3625" PostTypeId="2" ParentId="3612" CreationDate="2014-04-29T01:27:08.927" Score="12" Body="&lt;p&gt;Consider the case where you are flying into a headwind that equals the published speed for maximum range in still air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, if you fly at the speed for maximum range in still air, you will have a ground speed of zero, and a range of zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make any progress over the ground (to increase your range), you'll need to fly at an airspeed higher than the speed for maximum range in still air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual relationship is shown in Figure 5-19 of &lt;em&gt;The Illustrated Guide to Aerodynamics (2nd Edition)&lt;/em&gt;. Plot the Velocity-PowerRequired curve. Draw a line L starting at the point (velocity=headwind, power=0) that is tangent to the Velocity-PowerRequired curve. The point at which the line L touches the PowerRequired curve is at the speed for maximum range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZWe2i.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the chart caption is wrong. The chart shows the difference in speeds for maximum range, but I don't believe that the airspeed that gives the best L/D ratio is affected by wind.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="6" LastEditDate="2014-04-29T02:15:14.413" LastActivityDate="2014-04-29T02:15:14.413" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3626" PostTypeId="1" CreationDate="2014-04-29T05:58:03.973" Score="13" ViewCount="911" Body="&lt;p&gt;The answer for &lt;a href=&quot;https://aviation.stackexchange.com/a/3625/65&quot;&gt;How does wind affect the airspeed that I should fly for maximum range in an airplane?&lt;/a&gt; refers to a velocity/power-required curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can tell, this curve can't be deduced from information in the flight manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose one could experiment and determine what power setting is required in order to maintain level flight at a bunch of airspeeds (or for a glider, record the sink rate, which is proportional to the negative of the power-required, at a bunch of airspeeds). Would that be accurate enough? Are these curves available from the manufacturer?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-06-25T17:08:34.200" Title="How can I get the velocity-power curve for a particular aircraft?" Tags="&lt;aircraft-performance&gt;&lt;theory&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3627" PostTypeId="5" CreationDate="2014-04-29T12:46:22.193" Score="0" Body="&lt;p&gt;Visual meteorological conditions are the conditions where the pilot has sufficient visibility to fly visually.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-29T12:59:59.393" LastActivityDate="2014-04-29T12:59:59.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3628" PostTypeId="4" CreationDate="2014-04-29T12:46:22.193" Score="0" Body="for questions about Visual meteorological conditions." OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-04-29T14:30:06.067" LastActivityDate="2014-04-29T14:30:06.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3630" PostTypeId="2" ParentId="3494" CreationDate="2014-04-29T13:27:37.517" Score="1" Body="&lt;p&gt;I don't know for certain about the Fokker, but most autobrake systems are designed to produce a specific rate of retardation, using the equivilent of ABS and antiskid, which greatly increases passenger comfort. The effect of opening and closing spoliers, flaps and reverse thrust are all compenstaed for automatically so the pilot does not need to worry about adjusting braking force to maintain smoothness at a time of maximum stress. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disadvantages are that it is a system and can fail which is why every landing check list includes &quot;Verify Autobrake Operation&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less obvious advantages include reduced wear on braking systems, reduced tyre wear, automatic compensation for single wheel lockups etc.&lt;/p&gt;&#xA;" OwnerUserId="2233" LastActivityDate="2014-04-29T13:27:37.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3631" PostTypeId="2" ParentId="3581" CreationDate="2014-04-29T14:58:08.073" Score="6" Body="&lt;p&gt;There are two instances I remember hearing about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cnn.com/2013/03/04/us/new-york-drone-report/&quot;&gt;This one&lt;/a&gt; happened to a plane landing at JFK, and the FBI was seeking information about it. They reported seeing a small black &quot;drone aircraft&quot; with four propellers. I don't think they every found anything more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And &lt;a href=&quot;http://www.vancouversun.com/Radio+controlled+helicopter+serious+risk+collision+with+jetliner/9760947/story.html&quot;&gt;just recently&lt;/a&gt;, two planes landing at YVR saw an RC helicopter, one plane coming very close to it. The RCMP was investigating, but again it's not certain whether they will come up with anything about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also an &lt;a href=&quot;http://www.vancouversun.com/life/Transport+Canada+RCMP+investigate+unmanned+vehicle+close+commercial+flights/9764722/story.html&quot;&gt;investigation&lt;/a&gt; into a &lt;a href=&quot;http://www.vancouversun.com/opinion/letters/Video+plane+landing+Vancouver+International+Airport/9763138/story.html&quot;&gt;video&lt;/a&gt; taken from a quadrotor showing a plane landing at YVR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you thought that was close, check out this &lt;a href=&quot;http://www.youtube.com/watch?v=mZEgeTFFFDY&quot;&gt;video&lt;/a&gt; from Australia.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-04-29T14:58:08.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3633" PostTypeId="5" CreationDate="2014-04-29T16:54:13.040" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-04-29T16:54:13.040" LastActivityDate="2014-04-29T16:54:13.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3634" PostTypeId="4" CreationDate="2014-04-29T16:54:13.040" Score="0" Body="Use for flights shown on FR24, but not for issues with the site itself (e.g. coverage)." OwnerUserId="247" LastEditorUserId="14897" LastEditDate="2021-04-27T15:53:32.360" LastActivityDate="2021-04-27T15:53:32.360" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3635" PostTypeId="1" AcceptedAnswerId="3637" CreationDate="2014-04-29T17:15:38.937" Score="18" ViewCount="1806" Body="&lt;p&gt;What does ATC do when there is an emergency? This could be a tower or an ARTCC being evacuated or otherwise unusable.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How do they decide whether to close the airport/airspace?&lt;/li&gt;&#xA;&lt;li&gt;What do they do with the traffic, whether they do or don't close?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On this &lt;a href=&quot;https://aviation.stackexchange.com/questions/2924/why-was-this-helicopter-denied-entry-to-class-b-airspace/2927#2927&quot;&gt;related question&lt;/a&gt;, it turned out that Newark closed because of smoke in the tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another user posted an interesting anecdote about another tower being evacuated, so I thought it warranted a question.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-09-05T10:43:49.133" Title="How do airports handle traffic during emergencies?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3636" PostTypeId="2" ParentId="3614" CreationDate="2014-04-29T18:50:45.697" Score="5" Body="&lt;p&gt;To answer the &quot;title&quot; question (not the detailed questions below):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Approach with engine idled (which will mean the plane will be nose-down until you flare)&lt;/li&gt;&#xA;&lt;li&gt;Touchdown at slowest safe speed, hopefully just past the end of the runway&lt;/li&gt;&#xA;&lt;li&gt;Brake hard - really hard&lt;/li&gt;&#xA;&lt;li&gt;Retract flaps&lt;/li&gt;&#xA;&lt;li&gt;Push down the nose&lt;/li&gt;&#xA;&lt;li&gt;Basically you are trying to get as much weight onto the wheels as quickly as possible, which maximizes the effectiveness of your brakes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2238" LastActivityDate="2014-04-29T18:50:45.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3637" PostTypeId="2" ParentId="3635" CreationDate="2014-04-29T19:47:14.833" Score="13" Body="&lt;p&gt;The facility under duress will declare &quot;ATC Zero&quot; and all traffic will be handed off to other controllers while that facility is offline.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a control tower, this means the airport either acts as a non-towered field or as a closed field (depending on the nature of the emergency).  If it is a TRACON, then the ARTCC will assume control of the TRACONs airpsace.  If it is an ARTCC, that might present bigger problems as continuity of radio communications may be impacted and I'm not sure exactly how this would be handled but assume it would be re-routes around the ARTCC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been inbound to IAH when their tower decided to close (I forget why), and the response was to put everyone inbound to IAH into holds and handle diverts when fuel became an issue.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-29T19:47:14.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3638" PostTypeId="1" AcceptedAnswerId="3640" CreationDate="2014-04-29T20:12:52.540" Score="9" ViewCount="3988" Body="&lt;p&gt;Ok, so I'm a student pilot, and I'm going over the Vx, Vy, Vne, ... etc., and I see that &quot;maneuvering speed&quot; (the speed at which you can safely apply full flight controls) &quot;changes with weight&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which airspeeds &lt;strong&gt;don't&lt;/strong&gt; change with weight? I can pretty much guarantee the the takeoff speed changes with weight, as would flap operating speeds, never exceed speed, and cautionary zone, because that is just the basic application of physics (inertia).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do we treat maneuvering speed as the only variable airspeed?&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2014-05-01T07:53:09.783" Title="Don't all airspeeds change with weight?" Tags="&lt;airspeed&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3640" PostTypeId="2" ParentId="3638" CreationDate="2014-04-29T20:45:47.783" Score="14" Body="&lt;p&gt;Your instinct is correct; almost all of the key airspeeds — those at which something special happens aerodynamically — vary with weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a distinction, though, between &quot;speeds at which something special happens aerodynamically&quot; and &quot;regulatory limiting speeds that prevent you from doing something bad.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, &lt;i&gt;V&lt;sub&gt;NE&lt;/sub&gt;&lt;/i&gt; is a regulatory value; it is prohibited to exceed this speed at any weight. This value includes a safety margin and is determined from flight test data. Nothing special happens aerodynamically at the published &lt;i&gt;V&lt;sub&gt;NE&lt;/sub&gt;&lt;/i&gt; speed. (Thank goodness!) The special stuff, like &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroelastic_flutter#Flutter&quot;&gt;aeroelastic flutter&lt;/a&gt; or structural failure, happens at some speed well above &lt;i&gt;V&lt;sub&gt;NE&lt;/sub&gt;&lt;/i&gt;, regardless of your weight (as long as it's within the allowable CG envelope of course).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example, &lt;i&gt;V&lt;sub&gt;FE&lt;/sub&gt;&lt;/i&gt;, is similar. Nothing special happens at this speed. It's just a safety value: as long as you're below this speed, you won't tear the flaps off the plane if you extend them, regardless of your weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all speeds that aren't &quot;regulatory limits&quot; do indeed change with weight. Some examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;A&lt;/sub&gt;&lt;/i&gt; design maneuvering speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;X&lt;/sub&gt;&lt;/i&gt; best angle of climb speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;Y&lt;/sub&gt;&lt;/i&gt; best rate of climb speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;R&lt;/sub&gt;&lt;/i&gt; rotation speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;S0&lt;/sub&gt;&lt;/i&gt; landing configuration stall speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;S1&lt;/sub&gt;&lt;/i&gt; &quot;specific&quot; configuration stall speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For larger multi-engine airplanes that you'll encounter later in your flying career:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;1&lt;/sub&gt;&lt;/i&gt; engine failure recognition speed (or takeoff decision speed)&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;2&lt;/sub&gt;&lt;/i&gt; takeoff safety speed&lt;/li&gt;&#xA;&lt;li&gt;&lt;i&gt;V&lt;sub&gt;MC&lt;/sub&gt;&lt;/i&gt; minimum control speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(Note that a lot more factors besides just weight can go into these latter speeds, such as atmospheric conditions and &lt;a href=&quot;http://en.wikipedia.org/wiki/Flex_temp&quot;&gt;reduced-thrust takeoffs&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small airplanes, it is common to publish these speeds as single values, measured at gross weight. For many of them there are also graphs in the performance section that show you how the actual speed varies with weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For larger aircraft, the performance graphs (or calculations) are always used. For example, you won't use a single &quot;stall speed&quot; value from a handy table in the &quot;POH&quot; of a 747. In these types of aircraft, key numbers are calculated as needed on each flight for current weight.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-04-29T21:13:49.723" LastActivityDate="2014-04-29T21:13:49.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3641" PostTypeId="1" AcceptedAnswerId="3643" CreationDate="2014-04-29T20:48:22.287" Score="5" ViewCount="9015" Body="&lt;p&gt;What does &quot;best L/D&quot; mean? Is it meaningless without context? Do you need to know &quot;best for what?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, is it synonymous with max L/D?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="69" LastEditDate="2014-04-30T03:45:28.777" LastActivityDate="2014-04-30T21:04:00.237" Title="What is the definition of &quot;best L/D&quot;?" Tags="&lt;aerodynamics&gt;&lt;theory&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3642" PostTypeId="2" ParentId="3638" CreationDate="2014-04-29T21:11:32.770" Score="2" Body="&lt;p&gt;To explain why these speeds change with weight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;i&gt;V&lt;sub&gt;A&lt;/sub&gt;&lt;/i&gt; design maneuvering speed:&lt;/strong&gt; this is because it takes a lot more force to move a heavy plane than it does a lighter plane. On a lighter plane, the surfaces deflect, apply a force, and the plane moves. Once the plane is moving, the surfaces move too, which lessens the force on them. A heavier plane will move less, which means the surfaces are applying more force and for longer to move the plane the same amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;i&gt;V&lt;sub&gt;X&lt;/sub&gt;&lt;/i&gt; best angle of climb speed&lt;br/&gt;&#xA;&lt;i&gt;V&lt;sub&gt;Y&lt;/sub&gt;&lt;/i&gt; best rate of climb speed:&lt;/strong&gt; A heavier plane will need to produce more lift, and therefore have more drag, which affects climb performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;i&gt;V&lt;sub&gt;R&lt;/sub&gt;&lt;/i&gt; rotation speed&lt;br/&gt;&#xA;&lt;i&gt;V&lt;sub&gt;S0&lt;/sub&gt;&lt;/i&gt; landing configuration stall speed&lt;br/&gt;&#xA;&lt;i&gt;V&lt;sub&gt;S1&lt;/sub&gt;&lt;/i&gt; &quot;specific&quot; configuration stall speed:&lt;/strong&gt; A heavier plane needs more airspeed to produce enough lift to take off or not stall. Here is why:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among other things, lift is dependent on speed and angle of attack. So at a given speed, angle of attack can increase to generate more lift. The plane will have a maximum angle of attack above which it will stall. Since these are minimum speeds, they are at the maximum angle of attack, so speed must increase to provide the lift.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-29T21:31:05.823" LastActivityDate="2014-04-29T21:31:05.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3643" PostTypeId="2" ParentId="3641" CreationDate="2014-04-29T21:38:45.750" Score="3" Body="&lt;p&gt;Best $L/D$ is short hand for the airspeed where you have the best ratio of Lift to Drag, and is the same as $\textrm{max}\ L/D$.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you graph Airspeed -vs- the $L/D$ ratio, it will look something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mathworks.com/help/aerotbx/examples/astglide_01.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tBvTi.png&quot; alt=&quot;Best L/D Graph&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The peak point of the graph would be the &quot;best&quot; $L/D$ and represents the airspeed where the airplane is the most aerodynamically efficient.  For unpowered flight, it is the airspeed which will result in the best glide ratio.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2014-04-30T20:45:08.820" LastActivityDate="2014-04-30T20:45:08.820" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3644" PostTypeId="2" ParentId="3635" CreationDate="2014-04-29T21:44:25.563" Score="9" Body="&lt;p&gt;I happened to arrive in the Bridgeport, CT tower for a tower tour precisely when the boss (offsite) called an evac drill. KBDR is a non-radar tower. The two people in the tower picked up battery powered radios and evacuated to the parking lot, and continued controlling traffic from there. The controller on duty had/has a mental picture of the traffic and (at that low volume airport) he could operate just as well from the parking lot as from the tower. &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-04-29T21:44:25.563" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3645" PostTypeId="1" AcceptedAnswerId="3652" CreationDate="2014-04-29T21:46:47.623" Score="9" ViewCount="1005" Body="&lt;p&gt;Here is a $C_L$ / $AoA$ curve that I took from &lt;a href=&quot;http://en.wikipedia.org/wiki/Angle_of_attack&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Angle of attack&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/36LrS.png&quot; alt=&quot;Cl vs AoA - two points indicated, one before critical angle, one after&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The better textbooks say that a stall is &lt;em&gt;that condition in which a further increase in angle of attack will result in a reduction of lift&lt;/em&gt;.  The point at which that transition happens is known as the critical angle of attack.  Theoretically, sustained flight is possible at angles beyond the critical angle of attack - take a look at the chart.  If the airplane can sustain level flight at point $A$, it can sustain level flight at point $B$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there a practical way that I can demonstrate sustained flight on the backside of the lift curve without an angle of attack indicator?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or to ask the question another way,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there a practical way to tell when an airplane has exceeded the critical angle of attack without an AoA meter?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="247" LastEditDate="2014-04-30T04:04:43.783" LastActivityDate="2015-11-29T23:10:43.373" Title="Is there a practical way to demonstrate sustained flight on the back side of the lift curve without an AoA meter?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3646" PostTypeId="2" ParentId="3645" CreationDate="2014-04-29T21:52:16.070" Score="5" Body="&lt;p&gt;Increase the aircraft's pitch in level flight. If you climb, you are on the good side of the curve. If you sink, you are on the bad side. This will only be the initial response of the aircraft, as the airspeed will start to change and further affect the aircraft's behavior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without an AOA meter, you would have to look at your artificial horizon and vertical speed.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-04-30T15:40:27.503" LastActivityDate="2014-04-30T15:40:27.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3647" PostTypeId="2" ParentId="3645" CreationDate="2014-04-30T02:25:48.033" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a practical way that I can demonstrate sustained flight on the backside of the lift curve without an angle of attack indicator?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Set up the aircraft for stalls, do all the stall safety checks. Fly slowly, so that you're near the peak of that curve. Pitch up sharply and confidently while adding power. When you've done the right amount of both, you'll find that the aircraft remains more or less in level flight. Make adjustments to zero the vertical speed, remembering that if you're climbing, you want &lt;em&gt;more up pitch&lt;/em&gt; to stop it in this configuration, and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. I'm no instructor and my flying hours are limited, but I was taught to do this during my initial training. I suppose how easy this is depends strongly on the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2194" LastActivityDate="2014-04-30T02:25:48.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3648" PostTypeId="2" ParentId="3622" CreationDate="2014-04-30T03:03:08.967" Score="-2" Body="&lt;p&gt;&quot;Poorly&quot; would be the direct answer to the title.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While each airline certainly has internal policies they are not utilized all that often (that's good) so when things do go boom everyone is out of practice. Having a well-rehearsed policy could be considered a liability issue - they expect things to crash often. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-04-30T03:03:08.967" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3649" PostTypeId="1" AcceptedAnswerId="3659" CreationDate="2014-04-30T03:33:36.003" Score="19" ViewCount="2913" Body="&lt;p&gt;A few times, when flying into SFO, me and my fellow passengers were informed that due to foggy weather one of two parallel runways there is closed, causing delays. So, a few questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why can only one runway be used during fog? During an instrument landing, if the instruments are precise enough to land the plane exactly in the middle of &lt;em&gt;one&lt;/em&gt; runway, then surely they are precise enough to differentiate between two runways?&lt;/li&gt;&#xA;&lt;li&gt;Is this standard practice in all airports or something specific to SFO? Is there some minimum distance between parallel runways above which it is safe to keep them both open in foggy weather?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2243" LastEditorUserId="22726" LastEditDate="2018-06-05T17:45:24.410" LastActivityDate="2018-11-18T20:08:17.013" Title="Why is one of two parallel runways sometimes closed in foggy weather?" Tags="&lt;weather&gt;&lt;runways&gt;&lt;closed-runways&gt;&lt;sfo&gt;&lt;parallel-runways&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3651" PostTypeId="2" ParentId="3649" CreationDate="2014-04-30T04:52:35.707" Score="19" Body="&lt;p&gt;SFO makes use of simultaneous close parallel approach operations.  This allows higher density operations than would otherwise be possible for runways spaced so close, but to make use of these ops, in SFOs case, requires 1600 ft ceilings and 4 sm visibility due to the requirement that aircraft maintain visual contact during close parallel operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does look like SFO can run the ILS approaches simultaneously outside of close parallel operations, but is possible the required spacing makes its pointless to use both runways.  If weather was bad enough that cat II ops were in effect, I don't see any verbiage on the cat II charts indicating simultaneous ops are approved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of how precise your instruments are, there are strict requirements on how close you can be to another airplane in the approach phase and that separation be maintained if both parallel aircraft perform the missed approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ability to run parallel approaches in low visibility depends on how far apart the runways are laterally.  Airports like IAH and ATL can run triple parallel ops and if you take a look at their runway layout you will find they are spaced quite far apart and may be displaced relative to one another.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-04-30T04:52:35.707" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3652" PostTypeId="2" ParentId="3645" CreationDate="2014-04-30T06:38:22.897" Score="7" Body="&lt;p&gt;Flight on the backside of the stallcurve is unstable; any (infinite small) increase in AoA will result in less lift. Less lift will cause the flightpath angle to decrease and the AoA to go up even more. To increase the lift, the nose has to be pitched down, but not so much that the stall is recovered otherwise you wouldn't call it sustained flight at the back of the AoA curve. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time you are also on the backside of the powercurve. This means that any reduction in airspeed would cause the drag to increase therefore decelerating the aircraft furthermore. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This double unstable situation would require a lot of fast responses from the pilot, probably causing too high workload. I doubt if it is practically possible to fly on the backside of the liftcurve without special automation.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-30T06:38:22.897" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3654" PostTypeId="2" ParentId="3281" CreationDate="2014-04-30T15:06:09.957" Score="5" Body="&lt;p&gt;Epilogue: I confirmed with my phase check CFI (and former DPE) that it's no big deal. She noted that the airplane designation &quot;can be lined through&quot; the day of the test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, the PPL doesn't mandate experience in a single type of aircraft, and anything one can fly in a PPL checkride requires instruction and an endorsement, so presumably the type can be adjusted even more significantly. (Whether it's a good idea is another matter entirely, but...)&lt;/p&gt;&#xA;" OwnerUserId="1042" LastActivityDate="2014-04-30T15:06:09.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3655" PostTypeId="1" AcceptedAnswerId="3657" CreationDate="2014-04-30T15:49:41.467" Score="19" ViewCount="5121" Body="&lt;p&gt;The toilets on passenger planes flush with an impressive amount of force - Is the negative pressure inside the tanks generated by a pump or are the tanks connected to the outside air pressure? Considering that the toilets should also work on the ground, I presume pumps are used - on the other hand, maybe the low pressure is stored inside the tanks from the last flight? Also, pumps would mean the toilets don't work when the aircraft is not powered up  - is this true? Also, how was the engineering problem solved of keeping the pumps or the tubes connecting to the outside free from waste?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2021-01-02T11:21:06.027" Title="How is the pressure difference in passenger plane toilets generated?" Tags="&lt;aircraft-design&gt;&lt;commercial-operations&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3656" PostTypeId="2" ParentId="3655" CreationDate="2014-04-30T16:24:55.127" Score="9" Body="&lt;p&gt;In &lt;a href=&quot;https://www.youtube.com/watch?v=0Oxtc4o0Q1I&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; is shown a test of the A380 system. At about the 0:48 mark the presenter remarks that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The toilets work by pumping air out of waste-tanks in the rear of the plane&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, at least in the A380 case, yes the negative pressure is achieved via pumps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your last question&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;how was the engineering problem solved of keeping the pumps or the tubes connecting to the outside free from waste?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you look at the video, you see that the pipes are connected on the top of the tank and the gravity will keep the waste away from the pump (in the assumption that no acrobatic maneuver will be performed, usually valid, but &lt;a href=&quot;https://aviation.stackexchange.com/questions/149/2698&quot;&gt;not always&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-16T22:49:17.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3657" PostTypeId="2" ParentId="3655" CreationDate="2014-04-30T16:25:03.697" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How is the pressure difference in passenger plane toilets generated?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pressure in flight is generated by using the vacuum outside. This dosen't work on the ground or at low altitude, so there's a pump as well to draw out the air to create an artificial vacuum.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Considering that the toilets should also work on the ground, I presume&#xA;  pumps are used - on the other hand, maybe the low pressure is stored&#xA;  inside the tanks from the last flight?&#xA;  Also, pumps would mean the toilets don't work when the aircraft is not&#xA;  powered up - is this true? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not sure about this one, but since the aircraft is seldom not powered when a person is onboard (maintenance can't do much without power either), I can't think of this being a significant problem. There might be a little bit of leftover pressure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus states that the vacuum pump is powered off the AC power bus, so it may be powered from the ground or the APU when the engines aren't on.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, how was the engineering problem&#xA;  solved of keeping the pumps or the tubes connecting to the outside&#xA;  free from waste?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As is seen in the picture below, the tank is rinsed out through with the help of a second port on the access cover to clean it out. The rest of the system I believe is designed to last until the next maintenance, when (I think) it's connected up to a high pressure hose to thoroughly clean it out.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A320 Toliet System:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6f02h.png&quot; alt=&quot;![toliet](http://4.bp.blogspot.com/_uaAGqzcfNRI/TD2zNFGAkZI/AAAAAAAABro/n9LjiV2550I/s640/AF443e.jpg)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=A320-Water_and_Waste.pdf&quot; rel=&quot;noreferrer&quot;&gt;A320 System&lt;/a&gt; Details.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-04-30T16:37:25.280" LastActivityDate="2014-04-30T16:37:25.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3658" PostTypeId="2" ParentId="3655" CreationDate="2014-04-30T16:25:16.613" Score="3" Body="&lt;p&gt;There is a vacuum-pump that draws the air out of the waste tanks. The whole system is under low pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a video explaining how the &lt;a href=&quot;https://www.youtube.com/watch?v=0Oxtc4o0Q1I&quot; rel=&quot;nofollow&quot;&gt;A380 toilet system&lt;/a&gt; works.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-04-30T16:25:16.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3659" PostTypeId="2" ParentId="3649" CreationDate="2014-04-30T16:53:58.303" Score="19" Body="&lt;p&gt;While ILS is precise enough to guide the aircraft precisely onto the runway, it is only so precise &lt;em&gt;in the immediate vicinity of the runway&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instrument measures &lt;em&gt;angular&lt;/em&gt; divergence from the runway axis. So while the one dot offset is just a few metres over threshold, it is much more at the point where the aircraft normally intercept the localizer, which is usually at least 10 miles out for large aircraft. At KSFO the runways are so close to each other that while the localizer could perhaps ensure separation in the final phase of landing, it can't ensure it in the earlier part.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-04-30T16:53:58.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3660" PostTypeId="1" AcceptedAnswerId="3662" CreationDate="2014-04-30T19:31:17.417" Score="10" ViewCount="859" Body="&lt;p&gt;Does an engine have to be at idle thrust for the reversers to deploy? If the engine is at higher than idle thrust, will it slow down to deploy the reversers and then speed up again, or can it just deploy the reversers at the higher thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am also asking about turboprops going into beta range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had this question based on the discussion on this question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3614/what-to-do-when-you-accidentally-land-on-a-runway-thats-borderline-long-enough-t&quot;&gt;What to do when you accidentally land on a runway thats borderline long enough to land on?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-02-19T15:13:55.197" Title="Is there an engine thrust level limit for deploying thrust reversers?" Tags="&lt;thrust-reverser&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3662" PostTypeId="2" ParentId="3660" CreationDate="2014-04-30T19:59:16.370" Score="9" Body="&lt;p&gt;Engines must be at idle thrust to enter reverse thrust.  This may not be 100% true of the physical action of engine entering reverse thrust (opening the buckets or translating the cowling), but it is required by the thrust levers.  In all airplanes I'm familiar with the thrust levers must be at idle to enter the reverse regime,  In the EMB-145 the reversage was below idle (i.e. you keep moving the levers aft) through a gate.  Even if the engine is capable of entering reverse thrust not at idle, there is no way to command it without first being at idle.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-05-01T16:09:29.117" LastActivityDate="2014-05-01T16:09:29.117" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3663" PostTypeId="2" ParentId="3641" CreationDate="2014-04-30T20:27:58.320" Score="3" Body="&lt;p&gt;What is &quot;best&quot; depends entirely on what you try to achieve. Without context it is meaningless. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to L/D curves, I can imagine you want to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;minimize your fuel burn per unit of time to stay aloft as long as possible&lt;/li&gt;&#xA;&lt;li&gt;minimize your fuel burn per unit of distance travelled to go far as possible&lt;/li&gt;&#xA;&lt;li&gt;climb as fast as possible&lt;/li&gt;&#xA;&lt;li&gt;climb as steep as possible&lt;/li&gt;&#xA;&lt;li&gt;descent slow at idle power&lt;/li&gt;&#xA;&lt;li&gt;glide far without engines&lt;/li&gt;&#xA;&lt;li&gt;maximize your fuel burn to prevent overweight landing in an emergency situation. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&quot;Best&quot; is different for most of the situations above, and mostly engine performance curves will play an important role as well to find the optimum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However there are two points on the L/D curve that are important:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\left.\frac{L}{D}\right|_{\textrm{max}}$ results in the lowest energy required per distance travelled and, disregarding propulsion efficiency, will give the most economical fuel consumption for long range travel. This will also give the best glide distance in unpowered flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\left.\frac{L^3}{D^2}\right|_{\textrm{max}}$ results in the lowest power required and, again disregarding propulsion efficiency, will give the lowest possible fuel flow. It will also result in the lowest sink rate in unpowered flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From googling around a bit it seems that in most situations when people talk about best L/D they seem to intend max L/D&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-04-30T21:04:00.237" LastActivityDate="2014-04-30T21:04:00.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3665" PostTypeId="2" ParentId="3626" CreationDate="2014-04-30T23:05:41.973" Score="3" Body="&lt;p&gt;You are right, this curve has to be tested. Of course, during development a lot of simulation and wind tunnel testing is done to get the power required, but it still needs to be confirmed in flight test. The interaction of power plant and airframe can be quite complex, and only testing will ensure that the data is correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is not part of the manual, the plane's manufacturer will certainly have the power curves. Did you ask them for the data? And I would expect that you will find some data points in any handbook which will allow you to approximate the power curve. Start from the trim condition (basically, thrust equals drag) and calculate the curve with the help of a parabolic polar. Like that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$T = c_D\cdot q\cdot S$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$P = T\cdot v = (c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon})\cdot v^3\cdot\frac{\rho}{2}\cdot S$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, now you need to get the zero-lift drag coefficient $c_{D0}$ somehow from one datapoint in the manual. Same goes for values like propeller efficiency or intake losses, because the listed power of the engine will not be what is effectively employed to generate thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $T$  thrust&lt;br&gt;&#xA;    $v$  airspeed&lt;br&gt;&#xA;    $q$  dynamic pressure&lt;br&gt;&#xA;    $\rho$  air density&lt;br&gt;&#xA;    $S$  wing area&lt;br&gt;&#xA;    $c_L$  lift coefficient&lt;br&gt;&#xA;    $AR$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon$  the wing's Oswald factor&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-30T23:05:41.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3666" PostTypeId="2" ParentId="1913" CreationDate="2014-04-30T23:25:41.473" Score="6" Body="&lt;p&gt;There have been tests of real aircraft in wind tunnels, with a pilot sitting in the cockpit. But in all cases the plane had been tied in place with strings. Trimming the lift and especially the thrust &lt;strong&gt;in all phases of the test&lt;/strong&gt; is really impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Messerschmitt 109 was tested in the French Chalais-Meudon tunnel in 1940, the Bell P-39 was tested at Langley, where the top speed could be improved from 340 to 392 MPH, the &lt;a href=&quot;http://enu.kz/repository/2009/AIAA-2009-623.pdf&quot; rel=&quot;noreferrer&quot;&gt;P-51&lt;/a&gt; was tested at Langley in 1943 like most small military planes of that period, and lately a stealth demonstrator made by MBB was tested in 1984, in most cases with the pilot in place. These are the ones I know; there were certainly more.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-04-30T23:25:41.473" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3667" PostTypeId="1" AcceptedAnswerId="9979" CreationDate="2014-04-30T23:39:02.830" Score="16" ViewCount="6982" Body="&lt;p&gt;Is it legal for a pilot with an FAA license to fly a foreign registered aircraft within the United States?  Is it covered by FAA regulations, or the country of aircraft registration?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2018-04-17T02:36:00.937" Title="Can a US pilot fly a foreign registered aircraft in the US?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3668" PostTypeId="1" AcceptedAnswerId="3675" CreationDate="2014-05-01T00:35:51.407" Score="-6" ViewCount="10120" Body="&lt;p&gt;Say for example you have a complete seal (unlikely) between yourself and the toilet. Is the amount of suction possible to pull one's intestines (or insides) out and into the toilet? I think (probably a joke) on a NASA show that the toilets in space can do that, but probably just meant jokily. But, back to the original question, is it possible?&lt;/p&gt;&#xA;" OwnerUserId="2248" LastEditorUserId="511" LastEditDate="2014-05-01T13:41:17.987" LastActivityDate="2014-05-01T13:47:17.567" Title="Can your intestines be sucked out by a commercial aircraft's toilet?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-05-01T16:12:44.447" ContentLicense="CC BY-SA 3.0" />
  <row Id="3669" PostTypeId="1" AcceptedAnswerId="3672" CreationDate="2014-05-01T04:12:59.053" Score="10" ViewCount="534" Body="&lt;p&gt;See &lt;a href=&quot;http://en.wikipedia.org/wiki/Drag_Polar&quot;&gt;Wikipedia:Drag polar&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Polar_curve_%28aviation%29&quot;&gt;Wikipedia:Polar curve (aviation)&lt;/a&gt; for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These curves are not on a &lt;a href=&quot;http://en.wikipedia.org/wiki/Polar_coordinate_system&quot;&gt;polar coordinate system&lt;/a&gt;. Why are they called polars?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="1467" LastEditDate="2016-05-24T06:58:17.227" LastActivityDate="2016-05-24T06:58:17.227" Title="Why are the power and drag curves called polars?" Tags="&lt;aircraft-performance&gt;&lt;terminology&gt;&lt;theory&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3670" PostTypeId="1" AcceptedAnswerId="3671" CreationDate="2014-05-01T04:45:20.793" Score="6" ViewCount="3988" Body="&lt;p&gt;Figure 10-5 of the FAA's &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; shows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NEFfp.png&quot; width=&quot;400&quot; /&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I didn't think $L/D_{MAX}$ coincided with $D_{MIN}$. Is this Figure accurate?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorDisplayName="user2168" LastEditDate="2014-05-01T05:09:37.453" LastActivityDate="2014-05-01T15:25:20.387" Title="Is the maximum lift-drag ratio found at minimum drag?" Tags="&lt;aircraft-performance&gt;&lt;theory&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3671" PostTypeId="2" ParentId="3670" CreationDate="2014-05-01T06:08:39.083" Score="9" Body="&lt;p&gt;Well, for all L/D curves and D curves, the assumption is that the weight of the aircraft is constant and that there is no acceleration. Therefore the lift equals the weight (neglecting the small vertical component of thrust). So lift is a constant in these curves. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest is simple mathematics; the maximum of $\frac{1}{f(x)}$ occurs at the minimum of $f(x)$ (when $f(x) &amp;gt; 0$), so the maximum of $\frac{L}{D}$ coincides with the minimum of $D$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O08Oz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-05-01T08:00:53.873" LastActivityDate="2014-05-01T08:00:53.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3672" PostTypeId="2" ParentId="3669" CreationDate="2014-05-01T07:00:56.997" Score="14" Body="&lt;p&gt;It is an historical name.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first polars were drawn by Otto Lilienthal in polar coordinates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.lilienthal-museum.de/olma/34.htm&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; (sorry, German link) we find an example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/64H9G.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="19" LastEditDate="2014-05-01T08:11:10.973" LastActivityDate="2014-05-01T08:11:10.973" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3673" PostTypeId="2" ParentId="3638" CreationDate="2014-05-01T07:53:09.783" Score="2" Body="&lt;p&gt;Well, top of my head: &lt;b&gt;V&lt;sub&gt;tyre&lt;/sub&gt;&lt;/b&gt; and &lt;b&gt;M&lt;sub&gt;MO&lt;/sub&gt;&lt;/b&gt; are two speeds which are totally independent of aircraft mass. The first is simply a tyre speed limitation and the second is aerodynamically determined by the wing. The rest should all change one way or another with mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why then use single values for most of these speeds? Well, for one thing, in smaller aircraft, those changes will ammount to 1,2 maybe 5 knots from &lt;em&gt;Basic Empty Mass&lt;/em&gt; to &lt;em&gt;Maximum Take Off Mass&lt;/em&gt;, so memorizing your stall speed as variable between 39 to 41.2 knots (when you have about +/- 5 kts accuracy on the airspeed indicator anyway) is pointless. Round it up to 45 and stay above that. Remember that most of these &quot;fixed&quot; speeds are CAS while some are EAS (and remember how that influences things), then remember those speeds will change from flight to flight depending on weight, but not too much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you get into slightly bigger airplanes you will start seeing the AFM giving 2 or 3 sets of speeds for different weights (850 kg, 1000kg, 1150kg) and it is your job to know them and interpolate them for today's weight.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-05-01T07:53:09.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3674" PostTypeId="2" ParentId="3670" CreationDate="2014-05-01T11:17:26.677" Score="6" Body="&lt;p&gt;Well, your lift equals weight, or the airplane drops out of the sky or climbs into orbit. Therefore, lift is constant. Then the point with minimum drag &lt;strong&gt;must&lt;/strong&gt; be the one where L/D reaches it's maximum.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-01T11:17:26.677" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3675" PostTypeId="2" ParentId="3668" CreationDate="2014-05-01T13:37:51.337" Score="5" Body="&lt;p&gt;Well, while kind of an odd question, there does happen to be a pretty simple answer so...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Mythbusters proved, &lt;a href=&quot;http://www.discovery.com/tv-shows/mythbusters/videos/airline-toilet-test.htm&quot; rel=&quot;noreferrer&quot;&gt;in one of their episodes&lt;/a&gt;, that the pressure differential created by an airline toilet seat isn't even enough to make a person be stuck to the seat itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it's fairly common knowledge (or can at least be assumed) that if you wanted to suck someones guts out of their body you would, as a first step, need to be able to create a proper vacuum seal between that person and the toilet seat.  Since it's impossible to create a proper vacuum seal with an airline toilet, we can deduce that that self same toilet lacks the power to suck out your organs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if you were worried, don't be.  Feel free to use that airline throne all you want ;).  &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-05-01T13:47:17.567" LastActivityDate="2014-05-01T13:47:17.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3677" PostTypeId="2" ParentId="3660" CreationDate="2014-05-01T18:57:48.607" Score="4" Body="&lt;p&gt;On 747-100 and -200 aircraft, each reverse thrust lever is mounted on the front side of it's respective thrust lever with the hinge above the reverse lever's end knob. If you should happen to grab the reverse thrust lever without having the forward thrust lever all the way back, the action of lifting the reverse thrust lever will force the forward thrust lever all the way back. When you lift reverse thrust lever to an almost-level position from it previous position parallel to the forward thrust lever, the buckets come out. That in itself provides considerable braking, and it's common to stop there. Continuing to lift and then bring back the reverse thrust levers spools up the engines. You need to be careful doing this. Coming back too far too fast might cause a compressor stall, especially on an already marginal engine. Compressor stalls on a Pratt and Whitney engine are no big deal. On a General Electric engine they are far more serious. As I remember, there was a lock-out that prevented an engine from moving into reverse thrust from other than idle thrust, but I can't remember how it worked, but I believe it required not just idle thrust but the aircraft also being on the ground (squat switches) and landing flap deployment.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-01T18:57:48.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3678" PostTypeId="2" ParentId="3667" CreationDate="2014-05-01T20:31:40.657" Score="0" Body="&lt;p&gt;There are reciprocity treaties requiring most countries to allow foreign aircraft to fly in their airspace. It probably depends on whether the country involved has such a treaty in place with the United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/international/bilateral_agreements/baa_basa_listing/&quot; rel=&quot;nofollow&quot;&gt;bilateral treaties&lt;/a&gt; and &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Aircraft-Ownership/Business-Justification/Importing-and-Exporting-Aircraft&quot; rel=&quot;nofollow&quot;&gt;AOPA importing requirements&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the FAA tolerates foreign aircraft to be operated in the US indefinitely so long as they meet airworthiness standards. In theory, they claim you have &quot;imported&quot; the aircraft and require you to re-register it, but this does not normally happen.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-05-01T20:31:40.657" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3679" PostTypeId="1" AcceptedAnswerId="3682" CreationDate="2014-05-01T20:46:42.233" Score="22" ViewCount="8100" Body="&lt;p&gt;The landing gear should be down in order to qualify as a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1271/what-is-a-stabilized-approach/1290&quot;&gt;stabilized approach&lt;/a&gt;. Other than that, what are the guidelines on when to deploy landing gear on approach?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2019-08-03T12:38:12.847" Title="When do pilots deploy landing gear?" Tags="&lt;landing&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3680" PostTypeId="1" CreationDate="2014-05-01T20:49:32.623" Score="16" ViewCount="17502" Body="&lt;p&gt;With respect to mid-air collisions, how is a near miss calculated, detected, and reported?  Does ATC have radar detection, or is it strictly up to pilots to report a close encounter with another aircraft?&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2015-08-28T19:25:39.603" Title="How is a near miss defined?" Tags="&lt;air-traffic-control&gt;&lt;tcas&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3681" PostTypeId="2" ParentId="3680" CreationDate="2014-05-01T21:16:37.030" Score="19" Body="&lt;p&gt;First I'd just like to comment that &quot;near miss&quot; is a bad term (as falstro also noticed). It seems to say that the planes &quot;nearly missed&quot;, implying they didn't miss. The FAA uses the terms &quot;Near Midair Collision&quot; (NMAC) for serious incidences, and &quot;loss of separation&quot; for less serious ones. As such, terms like &quot;near miss&quot;, &quot;close call&quot;, and &quot;narrowly escaped disaster&quot; are not well defined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC does usually have radar. The data is recorded and can be analyzed later. Of course, not all areas have radar coverage. In these cases it is up to pilots to report if they feel safety was compromised. They can use the &lt;a href=&quot;http://asrs.arc.nasa.gov/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Safety Reporting System&lt;/a&gt;, which is part of the &lt;a href=&quot;http://www.asias.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Safety Information Analysis and Sharing&lt;/a&gt; system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially with commercial flights, Traffic Collision Avoidance System (TCAS) is also used. If TCAS issues a Resolution Advisory (RA), which commands pilots to take action to avoid a collision, the pilots are usually required to report the incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &quot;loss of separation&quot; would be anything less than the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight&quot;&gt;required separation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According the the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A near midair collision is defined as an incident associated with the&#xA;  operation of an aircraft in which a possibility of collision occurs as&#xA;  a result of proximity of &lt;strong&gt;less than 500 feet&lt;/strong&gt; to another aircraft, or a&#xA;  report is received from a pilot or a flight crew member stating that a&#xA;  collision hazard existed between two or more aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That and more information about reporting incidents can be found in &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0706.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Section 6&lt;/a&gt; of the AIM.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-05-01T21:16:37.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3682" PostTypeId="2" ParentId="3679" CreationDate="2014-05-01T21:52:12.940" Score="22" Body="&lt;p&gt;As late as possible to still meet your company's specific stabilized approach guidelines (mine were 500 ft VMC, 1000 ft IMC).  If you need the drag, then use them earlier.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the EMB-145 in still wind or a headwind you could cross the FAF at 250 kts and clean and be on speed and configured by 1000' if you dropped the gear at the FAF (and opened the speed brakes and the first notch of flaps all at once).  Normally though, I'd drop the gear around 1000'.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Acronyms:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;VMC = visual meteorological conditions&lt;/li&gt;&#xA;&lt;li&gt;IMC = instrument meteorological conditions&lt;/li&gt;&#xA;&lt;li&gt;FAF = final approach fix&lt;/li&gt;&#xA;&lt;li&gt;EMB-145 is the type designator for the Embraer 145 regional jet&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastEditorUserId="247" LastEditDate="2014-05-19T04:48:35.660" LastActivityDate="2014-05-19T04:48:35.660" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3683" PostTypeId="1" AcceptedAnswerId="3684" CreationDate="2014-05-02T02:25:21.397" Score="8" ViewCount="1193" Body="&lt;p&gt;I have a question regarding this Missed Approach Procedure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Im in my final approach segment and reach DME 1.1 and the runway is not in sight so I start my Missed approach, how should it be executed?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Since I have to hold I'd start a tear drop entry turning to heading 125° and then left turn intercepting 275° course inbound. &lt;em&gt;This option sounds viable to me&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I first do a right 360° as charted (???) and going to the VOR and then starting probably a parallel entry into the hold. &lt;em&gt;This doesn't sound viable to me&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Textual description is also clear about that 360°&#xA;If it 1.) why would they chart that 360° there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IMDej.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1990" LastEditorUserId="100" LastEditDate="2020-05-05T11:10:52.980" LastActivityDate="2020-05-05T11:10:52.980" Title="How do you enter the hold after a missed approach at Riohacha (SKRH)?" Tags="&lt;approach&gt;&lt;sid-star&gt;&lt;missed-approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3684" PostTypeId="2" ParentId="3683" CreationDate="2014-05-02T03:07:24.377" Score="11" Body="&lt;p&gt;The missed approach is a climbing right turn to the VOR and then hold while climbing to 3000 ft.  The purpose of the 360 is probably to gain some altitude before entering the hold (someone with TERPS knowledge can address this).  The MSA where the hold is is 2000' and you start the missed at 390'.  The right turn will be protected starting at 390' wheras the hold is not, so you need to gain altitude before entering it.  Part of the issue here is that you can fly any entry you want, so the protected airspace for a hold (which determines its minimum altitude) is a somewhat large area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To fly it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Execute your missed approach items (flaps, gear, etc)&lt;/li&gt;&#xA;&lt;li&gt;Enter a climbing right turn direct to RHC VOR.  &lt;/li&gt;&#xA;&lt;li&gt;Upon reaching RHC VOR continue to climb and fly the holding entry of your choice&lt;/li&gt;&#xA;&lt;li&gt;Hold as published.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-05-02T03:07:24.377" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3685" PostTypeId="1" AcceptedAnswerId="3925" CreationDate="2014-05-02T03:39:45.560" Score="9" ViewCount="2228" Body="&lt;p&gt;If an autobrake setting is chosen prior to touchdown, but after touchdown and nosewheel compression (i.e. after the autobrake has engaged) a different setting is required, is it safe to change the setting during the roll-out? What happens when the setting is changed in this manner? I know application of manual brakes disables the autobrake. Does the autobrake immediately match the new deceleration requested?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="558" LastEditDate="2014-05-02T05:15:23.947" LastActivityDate="2017-04-02T16:00:55.520" Title="What is the effect of changing the autobrake setting after touchdown?" Tags="&lt;landing&gt;&lt;braking&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3686" PostTypeId="2" ParentId="1019" CreationDate="2014-05-02T03:58:53.627" Score="1" Body="&lt;p&gt;Details of RAIM calculation is explained in the paper  :&#xA;GPS EASY Suite II: easy13 - RAIM by Kai Borre&#xA;&lt;a href=&quot;http://www.insidegnss.com/auto/julyaug09-borre.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.insidegnss.com/auto/julyaug09-borre.pdf&lt;/a&gt;&#xA;Also the author gives a Matlab implementation.&#xA;Hope it helps.&lt;/p&gt;&#xA;" OwnerUserId="2254" LastActivityDate="2014-05-02T03:58:53.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3687" PostTypeId="1" AcceptedAnswerId="3688" CreationDate="2014-05-02T09:56:17.673" Score="11" ViewCount="1446" Body="&lt;p&gt;I believe it is mandatory for airlines to provide passengers with information about evacuation in case of emergencies. However, pretty much every accident I've ever heard off either happens at the airport (where normal exit routes are available) or in the middle of nowhere (where no passenger makes it out alive).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any statistics on how often do &quot;normal&quot; evacuations happen among Western airlines? The only example I can think off is the Hudson landing of &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;US Airways Flight 1549&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2172" LastActivityDate="2014-05-02T13:24:01.107" Title="How often does evacuation happen as shown during the pre-flight safety videos/stewardess instructions?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3688" PostTypeId="2" ParentId="3687" CreationDate="2014-05-02T12:40:03.653" Score="9" Body="&lt;p&gt;I didn't do statistics, but &lt;a href=&quot;http://avherald.com/&quot;&gt;The Aviation Herald&lt;/a&gt; lists units to low tens a year worldwide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of them happen at airport due to fire indication (sometimes even false) or smoke on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground, fire spreads a lot faster than while flying, because when flying, the wind is too strong and blowing the flames off. The most notable example would be &lt;a href=&quot;http://avherald.com/h?article=3f8fb20e&quot;&gt;China Airlines B738 at Okinawa on Aug. 20th 2007, airplane in flames arriving at stand&lt;/a&gt;. The aircraft was already at the gate when the flames were first noticed, evacuation was immediately initiated and by the time everybody left, it was already engulfed in flames, about 3 minutes after the fire started. While China Air might not be &quot;western&quot; in strict sense of the world, it is largest airline on Taiwan and follows the same standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another notable accident is &lt;a href=&quot;http://avherald.com/h?article=44078aa7&quot;&gt;Egyptair B772 at Cairo on Jul 29th 2011, cockpit fire&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some recent evacuations mentioned on AvHerald:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=46691d37&quot;&gt;Air France B773 at Paris on Jul 28th 2013, evacuation while boarding due to fumes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=46406feb&quot;&gt;US Airways B752 at Kona on Jun 8th 2013, evacuation during push back causes 4 injuries&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=460e76eb&quot;&gt;PSA CRJ2 near Philadelphia on Apr 17th 2013, smoke on board, evacuation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=44fe403b&quot;&gt;Easyjet A319 at Belfast on Jan 6th 2011, taxiway de-icing prompts evacuation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Notice, that they are all smoke or fire events. For some other reasons, see e.g.:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=46380ff0&quot;&gt;Wizz A320 at Rome on Jun 8th 2013, left main gear did not extend&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=469338e0&quot;&gt;Alitalia A320 at Rome on Sep 29th 2013, right main gear did not extend&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;two similar accidents where both aircraft were evacuated via slides. The reason in these, and many other gear collapse incidents, is that they don't want to wait in a damaged plane where there is a &lt;em&gt;risk&lt;/em&gt; of fire, plus the difficulty of getting stairs to the aircraft resting in strange attitude.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-05-02T13:24:01.107" LastActivityDate="2014-05-02T13:24:01.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3689" PostTypeId="2" ParentId="3645" CreationDate="2014-05-02T13:04:30.690" Score="2" Body="&lt;p&gt;The drag at point B in your chart is much higher than at point A, so you might not be able to trim level flight there. If you are willing to sacrifice altitude to compensate for missing thrust, the lift at point B will be sufficient to trim a quasi-steady flight condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying beyond stall requires sufficient pitch authority, so you might not be able to trim this condition with forward c.g. That said, your pitch response will be much weaker than in normal flight, and you can pull suddenly without much happening. Depending on your c.g. location, you will need to have your yoke/stick/whatever pulled way back to trim this condition, and if some more travel in pull direction remains, it will not help to further increase your angle of attack. Some aircraft will not let you stay in this condition and either drop the nose by themselves (which is good) or drop a wing (which is really bad), so try to experiment with enough altitude for recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My answer is Yes, if the aircraft lets you. Just watch the sink speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vAc5K.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vAc5K.png&quot; alt=&quot;Hoerner lift coefficient over 180°&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift coefficient over 180° for several NACA airfoils, taken from Sighard Hoerner's &lt;a href=&quot;http://de.scribd.com/doc/26107035/Hoerner-Fluid-Dynamic-Lift-1985&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fluid Dynamic Lift&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@DeltaLima is absolutely correct: While the lift curve slope is negative (the region around point B in your plot), the aircraft will be unstable and will drop out of this alpha range quickly. Note, however, that in the post stall region another section with positive lift curve slope follows, and here you can fly (well, let's better say mush) stably if the pitch control power of your aircraft allows. You will detect that you are in this region when your sink speed is much higher than at around stall, but the aircraft is in a stable state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air France&lt;/a&gt; demonstrated that you can keep an A330 in this condition for three minutes without any trouble. The trouble only starts when your altitude has run out.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-28T16:27:39.287" LastActivityDate="2015-11-28T16:27:39.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3690" PostTypeId="1" CreationDate="2014-05-02T15:27:32.463" Score="14" ViewCount="3430" Body="&lt;p&gt;There are many airplanes that claim to be the fastest piston, private jet, airliner, but what is the all time fastest airplane? How fast does it travel?&lt;/p&gt;&#xA;" OwnerUserId="423" LastEditorUserId="97" LastEditDate="2014-05-02T22:21:47.740" LastActivityDate="2014-05-09T20:29:14.107" Title="What is the fastest airplane?" Tags="&lt;aircraft-performance&gt;&lt;aircraft-identification&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3691" PostTypeId="2" ParentId="3690" CreationDate="2014-05-02T15:37:49.367" Score="36" Body="&lt;p&gt;This is a broad question. The Wikipedia page on &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_vehicle_speed_records#Aircraft&quot;&gt;vehicle speed records&lt;/a&gt; gives a nice breakdown by various categories. Some criteria are manned vs. unmanned, air-breathing vs. rocket, civilian vs. military.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fastest &lt;em&gt;manned, air-breathing&lt;/em&gt; aircraft was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot;&gt;Lockheed SR-71 Blackbird&lt;/a&gt; with an (unclassified) record of &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_airspeed_record&quot;&gt;2,193.2 mph on July 28, 1976&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some would consider the rocket-powered &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_X-15&quot;&gt;North American X-15&lt;/a&gt; the fastest &lt;em&gt;manned aircraft&lt;/em&gt; at 4,510 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you consider the Space Shuttle an &quot;aircraft&quot; during its re-entry phase, it passed Entry Interface at around 17,500 mph. This was unpowered flight though, and its speed dropped off as it entered the atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the rocket-boosted &lt;a href=&quot;http://en.wikipedia.org/wiki/HTV-2_Falcon&quot;&gt;HTV-2 Falcon&lt;/a&gt; currently qualifies as the fastest &lt;em&gt;unmanned aircraft&lt;/em&gt; at 13,201 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The record for the fastest human-made craft of any kind is currently held by the &lt;a href=&quot;http://en.wikipedia.org/wiki/Helios_probes&quot;&gt;Helios probes&lt;/a&gt;, at 157,078 mph. The fastest &lt;em&gt;manned&lt;/em&gt; human-made craft was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Apollo_10&quot;&gt;Apollo 10&lt;/a&gt; spacecraft at 24,790 mph. (Note that Apollo 10 holds the record not because it was any more or less capable than any other Apollo mission, but that its chosen moon fly-by trajectory resulted in a higher top speed relative to Earth. It could also have achieved a much higher top speed on a different trajectory had that been a goal for mission planners, but it wasn't.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, every single one of these is either military or NASA (not civilian). The fastest &lt;em&gt;civilian, air-breathing&lt;/em&gt; aircraft were the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-144&quot;&gt;Tupolev Tu-144&lt;/a&gt; supersonic transport at 1,518 mph, and its Western counterpart, the legendary &lt;a href=&quot;http://en.wikipedia.org/wiki/Concorde&quot;&gt;Aérospatiale-BAC Concorde&lt;/a&gt;, at 1,488 mph. Both are now retired. Several private organizations are developing civilian suborbital and orbital rocket-powered spacecraft; I'm not sure which is currently fastest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And though these aren't &lt;em&gt;crafts&lt;/em&gt; or &lt;em&gt;vehicles&lt;/em&gt;, honorable mentions go to a &lt;a href=&quot;http://en.wikipedia.org/wiki/Operation_Plumbbob#Propulsion_of_steel_plate_cap&quot;&gt;150,000 mph steel plate&lt;/a&gt; launched by a nuclear weapon, and to particle accelerators for propelling subatomic particles and &quot;man-made&quot; particle collision byproducts at ridiculously close to (99.99something percent of) the speed of light :-)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-05-09T18:56:09.977" LastActivityDate="2014-05-09T18:56:09.977" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="3692" PostTypeId="2" ParentId="3690" CreationDate="2014-05-02T15:38:51.973" Score="6" Body="&lt;p&gt;At present (and since 1976) &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed SR-71 Blackbird&lt;/a&gt; holds record for the fastest aircraft. As mentioned &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Records&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The SR-71 was the world's fastest and highest-flying operational&#xA;  manned aircraft throughout its career. On 28 July 1976, SR-71 serial&#xA;  number 61-7962, broke the world record: an &quot;absolute altitude record&quot;&#xA;  of 85,069 feet (25,929 m).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The speed it traveled was &lt;strong&gt;1,905.81&lt;/strong&gt; knots (2,193.2 mph; 3,529.6 km/h), approximately Mach 3.3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j14tG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A list of airspeed record is on &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_airspeed_record&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-05-02T15:38:51.973" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3693" PostTypeId="1" AcceptedAnswerId="3695" CreationDate="2014-05-02T17:43:37.903" Score="4" ViewCount="7696" Body="&lt;p&gt;I read once that the speed of sound decreases as altitude increases.  I wonder if that's true and, if so, are the pressure waves made at high altitude lesser than the ones at low altitude because of the difference in air pressure?  And, lastly, does that mean that lower speeds at higher altitudes will be subject to the problems one encounters when approaching mach speed?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="572" LastEditDate="2015-02-19T09:39:47.657" LastActivityDate="2019-03-11T12:44:12.787" Title="How does altitude affect the speed of sound?" Tags="&lt;aircraft-performance&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3694" PostTypeId="1" AcceptedAnswerId="3698" CreationDate="2014-05-02T17:51:57.693" Score="18" ViewCount="5304" Body="&lt;p&gt;I know on the 737, the leading edge slats deploy at the first flap setting, and the trailing edge flaps deploy after that at higher flaps settings. Why do the slats deploy before the trailing edge flaps?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LE Flap and slat schedule as it relates to TE Flap position for the 737-300:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/0FOIL.jpg&quot; alt=&quot;737-300 LE devices vs. flap position&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-05-21T22:37:58.350" LastActivityDate="2019-03-12T19:26:40.480" Title="Why do slats deploy first?" Tags="&lt;aerodynamics&gt;&lt;flaps&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3695" PostTypeId="2" ParentId="3693" CreationDate="2014-05-02T18:27:59.550" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I read once that Mach speed decreases as altitude increases.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The speed of sound is &lt;strong&gt;solely dependant on temperature&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$&#xA;M = \sqrt{\gamma RT}&#xA;$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where &lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt; is the ratio of specific heats, &lt;span class=&quot;math-container&quot;&gt;$R$&lt;/span&gt; is the molar gas constant and &lt;span class=&quot;math-container&quot;&gt;$T$&lt;/span&gt; is the temprature in Kelvin. For Earth's athmosphere at 15° Celsius, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$&#xA;M=\sqrt{1.4\times 287\times 288.15}=340\,\text{m}/\text{s}&#xA;$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does temprature decrease with altitude? Well, not always as can be seen by the international standard atmosphere:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sKvTk.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sKvTk.gif&quot; alt=&quot;ISA&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/atmos/atmtemp.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;cam.ac.uk&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;....are the pressure waves made at high altitude lesser than the ones at&#xA;  low altitude because of the difference in air pressure?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no simple answer to this. &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-016-DFRC.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here&lt;/a&gt;'s NASA's opinion:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Altitude determines the distance shock waves travel before reaching&#xA;  the ground, and this has the most significant effect on intensity. As&#xA;  the shock cone gets wider, and it moves outward and downward, its&#xA;  strength is reduced.&lt;/strong&gt; Generally, the higher the aircraft, the greater&#xA;  the distance the shock wave must travel, reducing the intensity of the&#xA;  sonic boom. Of all the factors influencing sonic booms, increasing&#xA;  altitude is the most effective method of reducing sonic boom&#xA;  intensity. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-11T12:44:12.787" LastActivityDate="2019-03-11T12:44:12.787" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="3696" PostTypeId="2" ParentId="3694" CreationDate="2014-05-02T18:46:58.727" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h5I67.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h5I67.jpg&quot; alt=&quot;liftcoefficant&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://forums.x-plane.org/uploads/monthly_11_2011/post-1379-0-49093100-1322514764.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;x-plane.org&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;What you can see here is that as the slats deploy, the lift coefficient in theory for the same angle of attack remains relatively unaffected. Only the angle of attack at which stall is reached is increased.&lt;/p&gt;&#xA;&lt;p&gt;This may be sensible because it increases the safety margin before deploying flaps particularly as these will increase drag which if left with the same power setting will increase the angle of attack to maintain the same vertical speed.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-12T19:26:40.480" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="3697" PostTypeId="2" ParentId="3694" CreationDate="2014-05-02T19:58:12.943" Score="6" Body="&lt;p&gt;Been long time since I learned this, but if memory serves me the slats produce more lift for less drag (more &quot;bang for your buck&quot;), whereas flaps are the reverse. On typical airliner (I'm a 767 captain at AAL) slats reduce your stall speed an average of 30 knots.&lt;/p&gt;&#xA;" OwnerUserId="2262" LastActivityDate="2014-05-02T19:58:12.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3698" PostTypeId="2" ParentId="3694" CreationDate="2014-05-02T21:33:30.110" Score="21" Body="&lt;p&gt;The slats help to protect the outer wing from stalling when the flaps deploy. The outer wing carries the ailerons, so there are no flaps, but the flaps inboard will induce more lift on the whole wing, raising the effective angle of attack even in the aileron section. Slats push the stall angle of attack up. Without the protection provided by the slats, the outer wing could stall, and if this happens on one wing first (very likely, there are many reasons for flow asymmetry), the aircraft will roll violently. To do so during an approach is not good at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at aircraft with powerful flaps: They all have slats at least on the outboard wing to avoid outer wing stall. One goes with the other.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-02T21:33:30.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3699" PostTypeId="2" ParentId="1726" CreationDate="2014-05-02T23:11:49.907" Score="13" Body="&lt;p&gt;Swing wings combine the high sweep angle helpful for Mach 2+ flight with tolerable low-speed handling characteristics. They were needed to fulfil the demands on military aircraft called for in tenders before planners realized in the late Sixties that &lt;a href=&quot;https://aviation.stackexchange.com/questions/21987/why-is-the-maximum-speed-of-current-fighter-aircraft-lower-than-those-from-the-1/21988#21988&quot;&gt;high speed was not needed&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying at supersonic speed, it helps if the sweep angle of the wing's leading edge is higher than the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8846/what-happens-when-an-aircraft-breaks-the-sound-barrier/8848#8848&quot;&gt;Mach cone angle&lt;/a&gt;. Since the Mach angle goes up with the arcsine of the Mach number, this requires more than 60° of sweep at Mach 2 and 70.5° at Mach 3. If the sweep angle of the leading edge is higher, the flow around it will still be &lt;a href=&quot;https://aviation.stackexchange.com/questions/32608/what-is-the-pressure-distribution-around-a-supersonic-wing/32609#32609&quot;&gt;similar to that of subsonic flow&lt;/a&gt; around a straight leading edge. This leaves effects like the &lt;a href=&quot;http://www.pdas.com/refs/tp1500.pdf&quot; rel=&quot;noreferrer&quot;&gt;suction peak near the leading edge&lt;/a&gt; in place which would disappear once the flow component perpendicular to the leading edge becomes supersonic. A subsonic leading edge greatly lowers drag at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sweep helps also to make the transition into the supersonic realm more gentle by lowering the drag maximum encountered around Mach 1. But below Mach 1 it starts to &lt;a href=&quot;https://aviation.stackexchange.com/questions/22757/what-is-the-reason-for-the-poor-low-speed-characteristics-of-sweptback-wings/22758#22758&quot;&gt;become a liability&lt;/a&gt;. Sweep &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;reduces maximum lift &lt;/li&gt;&#xA;&lt;li&gt;requires longer take-off and landing runs&lt;/li&gt;&#xA;&lt;li&gt;produces undesirable stall characteristics&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Therefore, a wing swept by more than 60° becomes rapidly irreconcilable with regular military requirements like short field length and good subsonic handling characteristics at high angle of attack. A swing wing is the only way to combine acceptable high- and low speed performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disadvantages listed above disappear below about 15° to 20° sweep, but the &lt;a href=&quot;https://aviation.stackexchange.com/questions/32790/how-does-the-shift-in-aerodynamic-center-affect-the-performance-of-swing-wing-ai/32796?s=1%7C0.1461#32796&quot;&gt;lengthwise travel of the wing's center of pressure&lt;/a&gt; with sweep angle is greatest at low sweep angles. In order to keep this lengthwise travel as small as possible, the regular range of sweep angles is mostly between about 20° and 70°.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;F-111&lt;/a&gt;: 16° - 72.5°, top speed Mach 2.5&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_F-14_Tomcat&quot; rel=&quot;noreferrer&quot;&gt;F-14&lt;/a&gt;: 20° - 68° (in flight), top speed Mach 2.34&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-23&quot; rel=&quot;noreferrer&quot;&gt;MiG-23&lt;/a&gt;: 16° - 72°, top speed Mach 2.32&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-24&quot; rel=&quot;noreferrer&quot;&gt;Su-24&lt;/a&gt;: 16° - 69°, top speed Mach 1.35&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-160&quot; rel=&quot;noreferrer&quot;&gt;Tu-160&lt;/a&gt;: 20° - 65°, top speed Mach 2.05&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Panavia_Tornado&quot; rel=&quot;noreferrer&quot;&gt;Panavia Tornado&lt;/a&gt;: 25° - 67°, top speed Mach 2.2&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;noreferrer&quot;&gt;B-1A&lt;/a&gt;: 15° - 67.5°, top speed Mach 2.22&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But there is more to sweeping wings:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main benefit for the B-1B  and the Tornado (which were both supposed to penetrate air defense at low altitude) is the lower lift slope of a swept wing, in combination with the high wing loading of a swing wing design. This translates into much better riding qualities in turbulent air. If the plane hits an updraft at high speed and in the high density air near the ground, the lift increase is massive if the wing is unswept. Sweeping it reduces the lift increase with the cosine of the sweep angle, and a gust which would have produced 4 g with the unswept wing produces only 2 g with 60° sweep. This effect is further increased by the change in wing span, which will reduce the load factor even more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other benefit is the possibility to use high-lift devices on the wing. The trailing edge comes forward and out for the landing configuration, so the pitching moment of the flaps can be controlled by the elevator and more air can be used for lift generation. Trailing edge flaps on a delta wing (which is basically the swept-back configuration), on the other hand, do not work well at all. This is helpful both for landing on a carrier and for taking off for a long-range bombing mission.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-01-22T07:05:25.877" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3701" PostTypeId="2" ParentId="2417" CreationDate="2014-05-03T21:03:53.633" Score="6" Body="&lt;p&gt;DeltaLima's answer is correct, but he doesn't say why there are oscillations. If you watch the horizon, you will see that initially and at the end of the spin the roll angle oscillates, whereas in the middle of the spin the roll angle is steady. The uneven altimeter correlates nicely with this roll oscillation. I assume that the static ports are at the rear fuselage, and during a spin the airflow will have a noticeable sideward component there. This will influence the pressure on the static port, and an oscillating change in this sideward component causes the halting movement of the altimeter.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-03T21:03:53.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3702" PostTypeId="1" CreationDate="2014-05-03T22:36:46.657" Score="69" ViewCount="29250" Body="&lt;p&gt;Why has someone not designed a landing wheel with a fin or fins on it so that the air will start the wheels turning before the wheels touch the ground? Wouldn't that preserve the tires longer from wear? Or would it make the control of the aircraft more dangerous in some circumstances, such as rain or snow, to have the wheels already turning when landing? If so, perhaps the fins could be manually or computer controlled for various weather conditions.&lt;/p&gt;&#xA;" OwnerUserId="2268" LastEditorUserId="790" LastEditDate="2014-05-04T11:05:31.370" LastActivityDate="2019-06-26T07:46:26.103" Title="Why are aircraft tires not pre-spun prior to landing to preserve them?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3703" PostTypeId="1" AcceptedAnswerId="3706" CreationDate="2014-05-04T05:14:26.670" Score="20" ViewCount="9355" Body="&lt;p&gt;The military throws away &lt;strong&gt;a lot&lt;/strong&gt; of equipment simply because it doesn't hold up to current standards. So I was wondering the following.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a fighter pilot, would you ever get a practice run ejecting out of a plane, or is it just kind of one of those things you read about and hope you never have to do it? What is it like ejecting out of a plane at 500 knots? 1000?&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="1467" LastEditDate="2017-06-09T08:02:50.437" LastActivityDate="2017-06-09T08:02:50.437" Title="Do you ever get to practice ejecting out of a plane as a fighter pilot?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;ejection-seat&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3704" PostTypeId="2" ParentId="3703" CreationDate="2014-05-04T05:54:50.777" Score="21" Body="&lt;p&gt;Ejecting at 1000 knots means ejection into supersonic flow. Not even the &lt;a href=&quot;http://www.zvezda-npp.ru/engl/k36-d.html&quot; rel=&quot;noreferrer&quot;&gt;Zvezda K-36&lt;/a&gt;, the indisputably best ejection seat around, is rated for that. For this kind of speed, &lt;a href=&quot;http://en.wikipedia.org/wiki/Escape_crew_capsule&quot; rel=&quot;noreferrer&quot;&gt;whole enclosures&lt;/a&gt; have been designed which did not work all too well when they had to be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MsNFq.jpg&quot; alt=&quot;Ejection seat test rig in action&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For training, there are &lt;a href=&quot;http://www.etcaircrewtraining.com/ejectionseat/&quot; rel=&quot;noreferrer&quot;&gt;simulators&lt;/a&gt; to prepare pilots for that hopefully rare occurrence (the picture above is from this link; there you'll find more pics and a list of their customers), but mostly, &lt;a href=&quot;http://www.ansys-blog.com/aircraft-ejection-seats/&quot; rel=&quot;noreferrer&quot;&gt;simulations&lt;/a&gt; are run with simulated pilots, too. The spinal loads are too high to have pilots exposed to them regularly without the benefits which go with a successful ejection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the things that might happen, see what &lt;a href=&quot;http://en.wikipedia.org/wiki/William_Rankin&quot; rel=&quot;noreferrer&quot;&gt;William Rankin went through&lt;/a&gt; on July 26, 1959. It can last quite a while, too. In his case 40 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, ejection seats started to save pilot's lives in 1942 (Germany) and 1945 &lt;a href=&quot;http://u-fr.blogspot.de/2011/01/early-swedish-ejection-seats.html#more&quot; rel=&quot;noreferrer&quot;&gt;(Sweden)&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:17:19.360" LastActivityDate="2015-05-07T06:17:19.360" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3705" PostTypeId="2" ParentId="3702" CreationDate="2014-05-04T06:19:03.663" Score="63" Body="&lt;p&gt;This has been researched over the years, but it seems that the solutions did not find wide application. The oldest I could find is from 1941 (see page 112 in &lt;a href=&quot;https://books.google.de/books?id=9iYDAAAAMBAJ&amp;amp;pg=PA80&amp;amp;dq=popular%20science%20%22September%201941%22&amp;amp;hl=en&amp;amp;ei=gZKRTKi3N82nnAeDrsDGCA&amp;amp;sa=X&amp;amp;oi=book_result&amp;amp;ct=result&amp;amp;redir_esc=y#v=onepage&amp;amp;q=popular%20science%20%22September%201941%22&amp;amp;f=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;the September 1941 issue of Popular Science&lt;/a&gt;), and there have been &lt;a href=&quot;https://web.archive.org/web/20161011070440/http://archives.sensorsmag.com/articles/0300/14/index.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;several attempts to implement&lt;/a&gt; a spin-up turbine. See &lt;a href=&quot;https://web.archive.org/web/20130118044142/https://www.newscientist.com/blog/invention/2007/11/wheels-with-wings.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;“Wheels with wings”&lt;/a&gt; on NewScientist Blogs or &lt;a href=&quot;http://www.eng-tips.com/viewthread.cfm?qid=293321&quot; rel=&quot;nofollow noreferrer&quot;&gt;“Spin Wheels Before Landing”&lt;/a&gt;, a discussion thread on Eng-Tips forums, for more. The biggest problem seems to be the inertia of the spinning wheel because it makes the aircraft react in funny ways if the pilot wants to correct his approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rough field package on the Cessna Citation 500 uses this technique (for the nose wheel only) to protect the fuselage from debris which could be kicked up by the wheel spinup.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-06-26T07:46:26.103" LastActivityDate="2019-06-26T07:46:26.103" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="3706" PostTypeId="2" ParentId="3703" CreationDate="2014-05-04T10:28:45.730" Score="26" Body="&lt;p&gt;Air forces use special training rigs rather than real ejection seats. &lt;a href=&quot;http://www.youtube.com/watch?v=riKkQ2GqZwA&quot; rel=&quot;noreferrer&quot;&gt;Example video&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a00bL.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Plenty of pilots have survived ejection (Wikipedia says &amp;quot;As of 20 June 2011 ... the number of lives saved by Martin-Baker products was 7,402 from 93 air forces&amp;quot;)&lt;/p&gt;&#xA;&lt;p&gt;The types of injury are illustrated by &lt;a href=&quot;http://emj.bmj.com/content/17/5/371.full&quot; rel=&quot;noreferrer&quot;&gt;this example&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The ejection seat has been responsible for saving the lives of thousands of pilots around the world since its introduction in the late 1940s. Typical survival rates quoted in the literature vary from 80–97%.&lt;/p&gt;&#xA;&lt;p&gt;It is generally accepted that radiographic evidence of vertebral fracture can be found in 30%–70% of aircrew after ejection&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The reason real ejection seats are not used is almost certainly the high risk of injury. Ejecting clear from a high speed jet requires a lot of acceleration.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-04T10:35:14.737" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3707" PostTypeId="1" CreationDate="2014-05-04T14:42:04.630" Score="12" ViewCount="4144" Body="&lt;p&gt;I'm trying to decode ADS-B messages for a school project, and I cannot reproduce the results of the NL() function as described in &lt;a href=&quot;http://www.eurocontrol.int/eec/gallery/content/public/document/eec/report/1995/002_Aircraft_Position_Report_using_DGPS_Mode-S.pdf&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; document. I've seen the same formula in several other documents. Also in this document is the reverse of this function - the NL is input, and the latitude &quot;boundary&quot; is the result. I cannot solve that either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've tried radians and degrees for the trig functions and several different calculation tools, and my result is never close to correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;known&quot; good inputs and result are from &lt;a href=&quot;http://www.lll.lu/~edward/edward/adsb/DecodingADSBposition.html&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; document. I've also seen these inputs and results elsewhere, but no details about the equation itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The summary of the &quot;known&quot; good data set is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$rLat = 10.2157745361328$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$NZ   = 60$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$NL   = 59$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equation is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;NL = int \left( 2 \pi \left[ arccos \left( 1 - { 1 - cos \left( {\pi \over 2NZ} \right) \over cos^2 \left( {2 \pi \over 180} \mid lat \mid \right) } \right) \right] ^{-1} \right)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone help me understand this calculation?&lt;/p&gt;&#xA;" OwnerUserId="2270" LastEditorUserId="1696" LastEditDate="2015-02-19T23:17:10.427" LastActivityDate="2018-08-03T17:55:47.227" Title="How does the ADS-B compact position report NL() function work?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3708" PostTypeId="1" AcceptedAnswerId="3725" CreationDate="2014-05-04T14:53:28.387" Score="23" ViewCount="3266" Body="&lt;p&gt;This is Ramstein air base in Germany,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Etgk9.jpg&quot; alt=&quot;Ramstein AB&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would you want to have runways converging (or diverging) like that, doesn't seem to do you much good in terms of parallel usage (either the approach, or the go-around would be exciting).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason I can think of is that it gives you more separation when launching aircraft in rapid succession, but then again only in one direction. And it's not like the military would bother much with separation anyway when there's a &amp;ndash; shall we say &amp;ndash; &lt;em&gt;pressing&lt;/em&gt; reason to get in the air fast.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-05-05T13:08:22.277" Title="Why have converging runways?" Tags="&lt;airport&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3709" PostTypeId="1" CreationDate="2014-05-04T16:49:17.193" Score="29" ViewCount="8451" Body="&lt;p&gt;The Socata TB10 checklist indicates that you should touch the brakes after lift-off. I assume this is to stop the wheels from turning, but why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a retractable gear aircraft this would make sense to avoid using anything in the wheel-well to stop the wheels and potentially causing damage or generate heat (as a side note, I think some airliners actually have brake-pads in the wheel wells for this purpose). However, the TB10 is not equipped with retractable gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TB10 and TB20 are very similar, and it might be a case of copy &amp;amp; paste between the two POHs (the TB10 POH also lists V-speeds for &quot;flaps and landing gear retracted&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do spinning wheels have an adverse effect on aerodynamics (or handling in general)? I would assume, if anything, they'd produce less drag. And as a cherry on top, I'd also assume they'd start spinning again fairly quickly, as only the lower part of the wheels are protruding out in to the air flow.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="247" LastEditDate="2014-05-05T10:10:26.673" LastActivityDate="2020-11-22T01:37:39.427" Title="Why tap the brakes on take-off in fixed gear aircraft?" Tags="&lt;takeoff&gt;&lt;landing-gear&gt;&lt;braking&gt;" AnswerCount="7" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3710" PostTypeId="2" ParentId="3709" CreationDate="2014-05-04T18:42:19.447" Score="6" Body="&lt;p&gt;Spinning wheels are not a problem in fixed undercarriage aircraft, there's no good reason to tap the brakes after takeoff if the gear is nailed down. I suspect you answered your own question when you theorized that they may have simply copied that part of the manual. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a wear perspective you may save some wear on the bearings by stopping the wheels spinning, but since you are using the brake pads to do it it's likely less overall wear just to let them stop naturally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;CLimbout is a busy time, anything that adds workload without a benefit shouldn't be on a checklist. I'd say you are probably safe to ignore that in a TB-10, however that is just my opinion and it may be worth contacting a TB-10 club and asking them what they think. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-05-04T18:42:19.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3711" PostTypeId="2" ParentId="3709" CreationDate="2014-05-04T20:23:29.427" Score="26" Body="&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/a/3705/524&quot;&gt;answer&lt;/a&gt; to another question has a &lt;a href=&quot;http://archives.sensorsmag.com/articles/0300/14/index.htm&quot; rel=&quot;noreferrer&quot;&gt;link&lt;/a&gt; suggesting that the spinning wheels may be sufficiently large gyroscopes to affect handling of the aircraft. That was however on a larger aircraft and higher speed (Lockheed Constellation). I don't know whether that effect would be observable on TB10.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-05-06T11:39:41.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3712" PostTypeId="2" ParentId="3709" CreationDate="2014-05-04T21:36:38.143" Score="22" Body="&lt;p&gt;On a Cessna 172, spinning wheels do create vibrations. Once the brakes are hit the vibrations stop. It could be due to the wheel balancing.&lt;/p&gt;&#xA;" OwnerUserId="2273" LastActivityDate="2014-05-04T21:36:38.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3713" PostTypeId="2" ParentId="3709" CreationDate="2014-05-04T22:55:20.090" Score="15" Body="&lt;p&gt;My initial hunch tells me that the reason for this is a bit of &lt;a href=&quot;http://en.wikipedia.org/wiki/Angular_momentum&quot; rel=&quot;nofollow noreferrer&quot;&gt;angular momentum&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember back when you were a kid, first learning to ride a bike? At some point you realized that the more speed you have, the more stable you are on your bicycle. This is because of angular momentum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So imagine your up in the air, and you have to wheels rotating at 75 rpm (assuming a takeoff speed of 55KIAS, no headwind, and a tire diameter of 18 inches). You have a decent amount of angular momentum &lt;strong&gt;fighting any maneuver that the aircraft wants to make.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consistency is key in safety in aviation. The difference in ground speed for a takeoff could vary from the Vr KIAS ± max head/tail wind. That's enough to significantly alter the dynamics of a maneuver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;--EDIT--&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know how much you are affected by this angular momentum, check out the question I posted on the physics stack exchange.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://physics.stackexchange.com/questions/111353/what-is-the-inertia-caused-by-angular-momentum-when-twisted-on-its-rotating-axi/111422&quot;&gt;https://physics.stackexchange.com/questions/111353/what-is-the-inertia-caused-by-angular-momentum-when-twisted-on-its-rotating-axi/111422&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2016-02-09T15:31:35.710" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3714" PostTypeId="1" AcceptedAnswerId="3726" CreationDate="2014-05-05T05:18:38.557" Score="3" ViewCount="152" Body="&lt;p&gt;The Avidyne R9 records flight data five times per second and can &lt;a href=&quot;http://www.youtube.com/watch?v=e7GwjMk6HuI&quot; rel=&quot;nofollow&quot;&gt;export it for later analysis&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in parsing this data and exporting it to Google Earth / X-Plane for visualization.  &lt;a href=&quot;http://www.cirrusreports.com&quot; rel=&quot;nofollow&quot;&gt;Cirrusreports&lt;/a&gt; already does this, so I know it's possible.  It would be easier, though, if there was a spec already out there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there a specification for the Avidyne R9 flight data file format available, preferably online?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="19" LastEditDate="2017-01-20T08:55:21.423" LastActivityDate="2017-01-20T08:55:21.423" Title="What is the format specification for Avidyne R9 flight data?" Tags="&lt;avionics&gt;&lt;flight-data-recorder&gt;&lt;software&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3715" PostTypeId="1" AcceptedAnswerId="3731" CreationDate="2014-05-05T05:54:25.043" Score="11" ViewCount="1641" Body="&lt;p&gt;Assuming taxiing is not a consideration, in an airport with two parallel runways does the airport gain capacity by:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;having a single runway dedicated for landings and the other for take-offs, &lt;strong&gt;&lt;em&gt;or&lt;/em&gt;&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;is it best to have both take-offs and landings from both runways? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Would there be other ways to divide the movements (say by class/size of aircraft)?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="22726" LastEditDate="2018-06-05T17:35:24.997" LastActivityDate="2018-06-05T17:35:24.997" Title="In parallel runway ops, is it better to dedicate a single runway to landings, or is it best to have a mix?" Tags="&lt;landing&gt;&lt;airport&gt;&lt;takeoff&gt;&lt;parallel-runways&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3716" PostTypeId="2" ParentId="3715" CreationDate="2014-05-05T07:02:07.300" Score="6" Body="&lt;p&gt;That would no doubt depend on a lot of factors. Geometry for example. If the parallels are far enough apart there's no chance of a missed approach on one interfering with traffic on the other, you're a lot more flexible than when they're close together.&lt;br/&gt;&#xA;Maybe you have noise abatement procedures that make the use of one of the runways for either landing or departures illegal at specific times (e.g. Schiphol can't use certain approaches during the morning rush because overflight of parts of the city are not allowed at those times).&lt;br/&gt;&#xA;Type of traffic is another. If you're getting a lot of inbound heavies at an hour where you have a lot of outgoing smaller aircraft, it soon becomes a good idea to have one runway set aside during that period for landings, one for arrivals (the wake turbulence of the heavies would mean longer waiting times on the runway for the lighter aircraft).&lt;br/&gt;&#xA;So overall, there's no definite answer. It all depends on traffic, local conditions, etc. etc.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-05-05T07:02:07.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3717" PostTypeId="2" ParentId="3708" CreationDate="2014-05-05T07:09:47.903" Score="1" Body="&lt;p&gt;Diverging departure paths during a surge (remember Ramstein is a military base, and used to have QRA interceptors on standby 24/7) is probably the main reason here.&lt;br/&gt;&#xA;Shaves a few seconds from the time needed to get all the aircraft in the air in an emergency.&lt;br/&gt;&#xA;Landing them all rapidly is less important, as most would be expected to not make it home, such is the nature of military planning for all out war.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;As you can see, the alert pads are at the end from which the runways diverge (the far end in your photo), at the other end there's no quick way to enter the runways at all (you need to backtrack along one to reach the treshold of the other). As these would have been constructed with the prevailing winds in mind, that's no real problem.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-05-05T07:09:47.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3718" PostTypeId="2" ParentId="3702" CreationDate="2014-05-05T08:30:52.100" Score="12" Body="&lt;p&gt;It's just not cost-efficient. Any weight-add produces more fuel consumption, any systems produces more maintenance costs. It's just easier to change the tires if they're worn out.&#xA;source: Aerospace engineering&lt;/p&gt;&#xA;" OwnerUserId="2274" LastActivityDate="2014-05-05T08:30:52.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3719" PostTypeId="1" AcceptedAnswerId="3720" CreationDate="2014-05-05T09:05:40.900" Score="6" ViewCount="1054" Body="&lt;p&gt;This a shot of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aero_Synergie_Papango&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aero Synergie Papango&lt;/a&gt; ultralight, the succesor of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aero_Synergie_J300_Joker&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aero Synergie J300 Joker&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fQ949.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings are more elaborate compared to its predecessor's and include on their top two additional extensions/devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they? Any aerodynamic role or just for aesthetic sake?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-05-05T10:31:51.977" LastActivityDate="2018-10-26T14:17:59.703" Title="What is this extension/device on top of the wing of this ultralight?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;ultralight&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3720" PostTypeId="2" ParentId="3719" CreationDate="2014-05-05T09:10:52.870" Score="11" Body="&lt;p&gt;Those are &lt;a href=&quot;http://en.wikipedia.org/wiki/Wing_fence&quot; rel=&quot;nofollow noreferrer&quot;&gt;wing fences&lt;/a&gt; and they prevent airflow perpendicular to the direction of travel. This isolates the portions of the wing and allows the inner wing to stall independently of the outer wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the wing uses flaps, the inner portion will create more lift and stall (separation of airflow on the upper wing leading to loss of lift) at a lower angle of attack. Wing fences prevent this stall from extending over the outer part with the ailerons, so the airplane will stay controllable in a stall and will not suddenly drop one wing.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2018-10-26T14:17:59.703" LastActivityDate="2018-10-26T14:17:59.703" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="3721" PostTypeId="2" ParentId="3707" CreationDate="2014-05-05T10:20:39.363" Score="12" Body="&lt;p&gt;Compact Position Reporting (CPR) is a way of reducing the number of bits needed to transmit position whilst maintaining high position resolution (~5.1 meters for airborne encoding). Ordinary encoding would require 45 bits, but CPR uses 35 bits thus saving 10 bits. To do so, the world is divided up into a number of zones, both for latitude and for longitude and the position within the zone is encoded. Since transmitting the zone numbers would cost as many bits as that would have been saved a clever trick is used. Two types of encoding are used, each with a different number of zones. From the difference in zone coordinates between the two types of encoding one can determine which zone the aircraft is in. Therefore one needs to receive an &lt;em&gt;even&lt;/em&gt; and an &lt;em&gt;odd&lt;/em&gt; encoded message within 10 seconds from each other. Once the initial position decoding is successful every subsequent position message will give the updated position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In CPR decoding, you first determine the latitude of the aircraft based on a pair of odd and even position messages received within 10 seconds from each other. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Latitude is always encoded in the same number of zones between the equator and the poles (15 for even encoding, 14.75 for odd encoding). Due to the roundness of the earth the numbers of zones used for longitude encoding depends on the latitude. Longitude even encoding uses 59 zones at the equator and only 1 at the poles. Odd encoding uses always 1 zone less, except near the pole where 1 zone is used like in even encoding. The number of longitude zones used for even encoding can be found by the $NL()$ function. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The transition latitudes, i.e. where the number of zones for longitude encoding change, can be calculated by the inverse $NL()$ function. This function can be used to create a lookup table of transition latitudes which is more efficient to use than the original $NL()$ function.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without knowing anything about your implementation it is difficult to assist further, the formula is depicted correctly in your question. Note that input latitude is given in degrees, but the trigonometric function are assumed to work on radians hence the $\frac{\pi}{180}$ factor. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: on further inspection I noticed a mistake in the formula: it should be :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;NL = int \left( 2 \pi \left[ arccos \left( 1 - { 1 - cos \left( {\pi \over 2NZ} \right) \over cos^2 \left( { \pi \over 180} \mid lat \mid \right) } \right) \right] ^{-1} \right)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(note that the conversion from degrees to radians is corrected)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those that really want to understand CPR coding and decoding in detail, you'll have to obtain a copy of RTCA document DO-260B or Eurocae document ED-102A (unfortunately they're expensive, I think about $700) and read Appendix A.1.7 and Appendix T. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2018-08-02T11:34:12.517" LastActivityDate="2018-08-02T11:34:12.517" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="3722" PostTypeId="1" AcceptedAnswerId="3723" CreationDate="2014-05-05T10:28:18.503" Score="12" ViewCount="3475" Body="&lt;p&gt;I was recently involved in a flight that had issues before take off. The plane was an Airbus 321.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was explained to me as being a &quot;wing loop fault&quot;. The problem was that the ECAM messages were displayed differently each time and were inconsistent. The flight was aborted just before take off (for safety reasons) but the problem was fixed soon after by replacing a part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone explain this problem with the wing loop to me in more detail. What could have gone wrong and what was the likely fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what maintenance and pre-flight checks should occur on the &quot;wing loop&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for any vagueness in my question, I didn't receive much information.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edits&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This was on aircraft G-OMYJ around the 24th August 2013&lt;/li&gt;&#xA;&lt;li&gt;My route was (EMA) --&gt; (DLM), flight TCX5894. But the fault may have occurred on the previous flight. The details are unfortunately hazy. Is there anyway of me finding the whereabouts of the plane in the days leading up to this incident?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2275" LastEditorUserId="14897" LastEditDate="2021-05-02T20:00:47.897" LastActivityDate="2021-05-02T20:00:47.897" Title="What is a 'Wing Loop Fault' on an A320 series Aircraft?" Tags="&lt;wing&gt;&lt;airbus-a320&gt;&lt;feature-identification&gt;&lt;aircraft-failure&gt;&lt;cockpit-alerts&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3723" PostTypeId="2" ParentId="3722" CreationDate="2014-05-05T11:26:33.220" Score="6" Body="&lt;p&gt;My guess is that there was some circuitry that was playing up. While I'm not sure about 'Wing Loops' specifically, for what I think is a similar example the Airbus A320 series has fire loops in the engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two fire loops. If I'm right, it's got little thermal sensors along way, which disrupt the current if they get too hot (or if the wire is broken). Logic gates ensure that both loops must be 'high' for the fire warning to go off. If one is not working, it works from a single input. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming both of these were working from the beginning, I think it throws a &lt;code&gt;FIRE DET FAULT&lt;/code&gt; warning on the pilot information display if one triggers without setting off the other one. I'd imagine that maintenance either disabled the faulty loop within those allowed by the &lt;em&gt;Minimum Equipment List&lt;/em&gt; or by changing the part. If it was quick, it was probably the first, but they're not going to go telling passengers that they disabled safety equipment :)&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-05-05T11:26:33.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3724" PostTypeId="2" ParentId="3722" CreationDate="2014-05-05T11:29:18.313" Score="5" Body="&lt;p&gt;It might be a problem with the loops of sensors for the fire detection systems etc&lt;/p&gt;&#xA;&lt;p&gt;For example: ECAM message &lt;em&gt;&amp;quot;FIRE LOOP A FAULT&amp;quot;&lt;/em&gt; (ATA 49: APU)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Both engines and the APU each have two identical loops, A &amp;amp; B and a computer- FDU (Fire Detection Unit). A fire warning is given when both loops reach the proper overheat condition. If one loop fails the other loop is able to generate the warning by itself. A fire warning is given if both loops fail within 5 seconds of each other.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;The leak detection system uses a single loop for the pylons and APU to detect hot air temps associated with duct leaks. Dual loops are used for the wings. If both of the dual loops detect a leak a warning is given, unless there is a fault on one, then only one loop is required to give a warning.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From Eric Parks training notes.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-05T11:29:18.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3725" PostTypeId="2" ParentId="3708" CreationDate="2014-05-05T13:08:22.277" Score="16" Body="&lt;p&gt;Ramstein is a major US logistics airbase in Germany. Originally Ramstein used to have only one runway. The runway was built with fighter aircraft in mind and could also host C-130 Hercules aircraft. Bigger freight aircraft and passenger aircraft could not use Ramstein and were handled at Rhein-Main base, which was at Frankfurt's international airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When Frankfurt needed to expand their civil operations, Rhein-Main base was closed and all the US military tranport operations were transfered to Ramstein. In order to accomodate the big transport aircraft at Ramstein, the airport needed an upgrade. To keep the base open during construction works it was elected to convert the old India taxiway into a runway (08-26) which was made longer, wider and thicker that the original 09-27 runway. Also new aprons were added to the North and South of the runways. When the work was completed in 2005, the old runway was closed for reconstruction. It was then resurfaced and extended so that since 2008 there are two operational runways at the airport, so that in case of maintenance or an incident the operations can continue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no relation to launching fighter aircraft in rapid succession.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-05-05T13:08:22.277" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3726" PostTypeId="2" ParentId="3714" CreationDate="2014-05-05T15:37:44.267" Score="2" Body="&lt;p&gt;According to section 12-4 of the &lt;a href=&quot;http://dealers.avidyne.com/files/downloads/600-00190-000.pdf&quot; rel=&quot;nofollow&quot;&gt;Release 9 Pilot's Guide&lt;/a&gt;, data logs are saved as a simple .csv file that can imported into any spreadsheet software (like Microsoft Excel) for analysis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many free tools that can covert Excel files to KML for Google Earth, ie: &lt;a href=&quot;http://www.earthpoint.us/exceltokml.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.earthpoint.us/exceltokml.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-05-05T15:37:44.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3727" PostTypeId="1" AcceptedAnswerId="3732" CreationDate="2014-05-05T18:20:27.307" Score="14" ViewCount="12495" Body="&lt;p&gt;How precise and how accurate are typical altimeters these days? That is, if two planes are flying (side-by-side, very near each other), and both altimeters show the same Flight Level, what is the maximum vertical difference in actual altitude you would expect to see between them? (I.e. is it on the order of a few meters, a few tens of meters, etc?) Is there any legal standard for precision/accuracy of the altimeter that must be met (let's say in the US)?&lt;/p&gt;&#xA;" OwnerUserId="2243" LastActivityDate="2014-05-05T20:26:14.630" Title="How precise are altimeters?" Tags="&lt;flight-instruments&gt;&lt;avionics&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3728" PostTypeId="2" ParentId="3727" CreationDate="2014-05-05T18:44:14.393" Score="6" Body="&lt;p&gt;Well, it depends a little bit on how you define accuracy. Working altimeters are as accurate as the pilot makes them. In perfect use, they work great, in typical use, they work a little less great, but still pretty well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, the altimeter is part of the pitot-static system, so that means they are dependent on having smooth airflow, and the pitot-static system being working (not clogged).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, altimeters in GA airplanes, not sure about others, require you to manually set the pressure of the atmosphere (barometric pressure), to get the correct reading. This can be done with some accuracy, but usually never 100%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, altimeters in GA airplanes are required to be read in a similar manner to an analog clock. So there is a little pilot error to consider.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JQCVx.png&quot; alt=&quot;pilot readings&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2014-05-05T18:44:14.393" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3729" PostTypeId="5" CreationDate="2014-05-05T19:25:32.193" Score="0" Body="" OwnerUserId="65" LastEditorUserId="97" LastEditDate="2014-05-05T19:46:36.397" LastActivityDate="2014-05-05T19:46:36.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3730" PostTypeId="4" CreationDate="2014-05-05T19:25:32.193" Score="0" Body="This tag can be used for procedures and processes of evacuations, and events leading to an evacuation of an aircraft." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-05T19:45:58.590" LastActivityDate="2014-05-05T19:45:58.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3731" PostTypeId="2" ParentId="3715" CreationDate="2014-05-05T19:55:04.727" Score="6" Body="&lt;p&gt;There are a number of things to take into account:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The distance between the runways; can they be operated as independent runways? This requires the centrelines to be more than 1035 meter apart.&lt;/li&gt;&#xA;&lt;li&gt;The traffic mix: is there constantly the same distance between landings or a large gap every now and then between a Heavy and a Medium that allows for one or two departures in between? &lt;/li&gt;&#xA;&lt;li&gt;The runway entry and exit points. Can aircraft wait sufficiently short of the approach end to allow for a rapid departure when cleared for take-off? Does the runway have high-speed exit taxi-ways at appropriate places for the landing traffic to vacate the runway quickly or is a slow 90 degree turn required?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, mixed mode operations can increase capacity significantly. For example the estimate for London Heathrow is that the traffic could increase from &lt;a href=&quot;http://www.lbhf.gov.uk/Images/Heathrow%20expansion%20briefing%20note%20%281%20Feb%2008%29_tcm21-93349.pdf&quot; rel=&quot;nofollow&quot;&gt;480.000 to 540.000 movements&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But it is not a simple change. The requirements on ATC increase. For example, to monitor the parallel approaches, the update rate and accuracy of the surveillance system must meet higher standards than for single runway approaches. Also missed approach and emergency procedures need to be changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is an important noise issue; in mixed mode operations, all four runway ends are continuously exposed to aircraft noise, while in dedicated operations the departure end of one runway and the arrival end of the other is not exposed.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&quot;Back of the envelope&quot; estimation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity let's assume traffic that is only Medium wake category with 3NM final approach separation at about 150 knots groundspeed. This would result in ~75 seconds intervals between aircraft passing the threshold for a pure landing runway, allowing for 48 landing per hour. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In mixed mode, a line up and hold instruction would be given as soon as the landing aircraft is passed the numbers, so take-off will commence quickly after take-off clearance is given. The take-off clearance itself can be given as soon as the landing aircraft has vacated the runway, which should be about 60 seconds after it crossed the threshold. The take-off run itself is 30-40 seconds for B737 / A320 family aircraft. Let's add about 20 seconds reaction and engine spool up time + margin. The next landing aircraft can cross the threshold after lift-off. The interval would be ~ 120 seconds between landing aircraft, resulting in 30 landings per hour. But this can be done on two runways at the same time, effectively increasing the throughput by about 25% percent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above schedule is very idealised with pure alternating take-off and landings and little margin for error. If put in practice it will probably result in too many go arounds due to late take-offs, but it gives good idea of the capacity increase that is possible. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-05-06T15:46:09.843" LastActivityDate="2014-05-06T15:46:09.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3732" PostTypeId="2" ParentId="3727" CreationDate="2014-05-05T20:26:14.630" Score="15" Body="&lt;p&gt;While Accuracy and Precision are closely related, they're not the same thing.&lt;br&gt;&#xA;In the context of your question &lt;em&gt;both&lt;/em&gt; are important:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Accuracy&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the US altimeters are broadly required to comply with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=&amp;amp;r=PART&amp;amp;n=14y1.0.1.3.21#14:1.0.1.3.21.0.363.14.57&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 43 Appendix E&lt;/a&gt; limits for &lt;em&gt;accuracy&lt;/em&gt; (technically this is regulatory for IFR flight, but TSO'd &quot;sensitive altimeters&quot; will generally meet these requirements - at least when they left the factory - and that's what you're going to find in most aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accuracy requirements provided in FAR 43 are based on mechanical altimeters, and are subject to a number of requirements (friction error limits, hysterisis limits, etc.), but the test tables there are a good guide to the accuracy of &quot;typical&quot; altimeters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that the accuracy of sensitive altimeters depends on the pressure setting the pilot enters (an incorrect pressure setting could mean substantial error). In &quot;the flight levels&quot; everyone uses the same standard altimeter setting (29.92 inches of mercury / 1013 millibars) to avoid this issue (similarly the ATC transponder transmits an altitude assuming a pressure of 29.92 inches of mercury - ATC's computers correct that value based on local altimeter settings as required).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Depending on the design digital altimeters may also be immune to some of the accuracy-affecting issues in an analog/mechanical altimeter - for example a solid-state digital altimeter should not suffer from &quot;friction error&quot; as there's no rotating/moving shaft involved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Precision&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Analog altimeters are &quot;reasonably precise&quot; -- take this example:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/uwT7Y.jpg&quot; alt=&quot;It&amp;#39;s an altimeter!&quot;&gt;&lt;br&gt;&#xA;The tick marks are every 20 feet. One could easily eyeball 20 foot increments, and even 10 foot increments (with the pointer directly between two ticks). Similarly the pressure settings are marked every 0.02 inches of mercury (or 1mb), allowing for a fairly precise setting of the value.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Digital altimeters are &lt;em&gt;extremely&lt;/em&gt; precise (often offering one-foot precision in their display, and 0.01 inches of mercury for the pressure setting).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I believe the precision requirements for altimeter markings are specified in the relevant TSOs, but I don't have those documents handy.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In both cases the precision of the markings can exceed the accuracy of the device: At 10,000 feet the FARs allow an 80 foot tolerance, and whether your measurement is presented as a needle position (roughly to the nearest 10 feet) or a number (to the nearest foot) you could still be 79 feet higher or lower than you &quot;think&quot; you are and be &quot;within tolerance&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, combining all of this together - If we have two aircraft flying along indicating the same altitude (say 10,000 feet) and both altimeters are &lt;em&gt;perfect&lt;/em&gt; there will be zero feet of vertical separation between them (the static ports of each aircraft will be at the exact same altitude).&lt;br&gt;&#xA;On the other hand if both aircraft are at the outer edge of tolerance (one +80ft, one -80ft) there will be 160 feet of vertical separation between them (discounting visual &quot;slop&quot; in the analog altimeter and assuming the pointer is &lt;em&gt;perfectly&lt;/em&gt; on the line and the pressure setting is &lt;em&gt;perfectly&lt;/em&gt; dialed in).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(In either case the answer would be &quot;WAY TOO CLOSE!&quot;)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-05T20:26:14.630" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3733" PostTypeId="1" AcceptedAnswerId="3849" CreationDate="2014-05-06T04:07:34.620" Score="12" ViewCount="9736" Body="&lt;p&gt;I was recently on a flight aboard an Airbus A380 where the flight was delayed 2 hours. The reason was claimed to be a start valve fault on engine #4, where it was stuck closed. According to the captain, they were able to get the engine started after manually starting the engine at the gate. How does this work?&lt;/p&gt;&#xA;" OwnerUserId="72" LastEditorUserId="19" LastEditDate="2015-01-09T23:59:48.110" LastActivityDate="2020-08-13T19:37:41.113" Title="How do you start a jet engine if the start valve is stuck closed?" Tags="&lt;jet-engine&gt;&lt;engine-starting&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3734" PostTypeId="1" AcceptedAnswerId="3735" CreationDate="2014-05-06T08:07:43.210" Score="11" ViewCount="2357" Body="&lt;p&gt;I recently bought a simulator for tower controllers (&lt;a href=&quot;http://www.atcsuite.com/index.html&quot;&gt;Tower! 2011&lt;/a&gt;) and have some questions about the responsibilities of the tower controller:&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When an aircraft wants to land at 'my' airport I get contacted once they are established on the approach path and already have a runway assigned (&quot;Tower, N1234 with you runway 26L&quot;).&lt;br&gt;Unfortunately sometimes it happens that aircrafts are assigned a runway that is actually to short form them to land - which I found out the hard way by getting punished because the plane was not able to stop on the runway.&lt;br&gt;Who is responsible to assign the correct runway in real-life, the tower controller or the approach controller? If if were up to the approach controller that would basically be a bug in the simulator.&lt;br&gt;&lt;/li&gt;&#xA;&lt;li&gt;Who decides which runway exit an aircraft will use after landing?&lt;br&gt;Again in the simulator I can advise the aircraft to taxi to the terminal via a certain route (&quot;N1234 taxi to terminal via L4 M4 N4&quot;) with L4 being the exit from the runway I want this aircraft to take. Unfortunately the aircrafts - in the simulator - decide which exit they are going to use on their own. So it might happen that the aircraft I assigned the route to exits the runway at exit L5 and therefore cannot comply with my assignment.&lt;br&gt;How is that handled in real-life? Does the pilot land the plane and then report back where he is (if I queried the airplane for a position I get a &quot;N1234 is on the ground&quot;) or does the tower controller assign an exit that the pilot needs to take - and therefore the simulator would have a bug?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2279" LastEditorUserId="1696" LastEditDate="2015-02-19T22:32:09.870" LastActivityDate="2015-02-19T22:32:09.870" Title="Who assigns an arriving aircraft a runway and runway exit to use?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;&lt;approach&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3735" PostTypeId="2" ParentId="3734" CreationDate="2014-05-06T08:28:18.687" Score="15" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The tower gives the ultimate clearance to land, though the approach controller (if one is available) assigns a specific approach to a runway in the approach clearance. I'm not sure about the game, however in real life if the runway was too short to land on, the pilot would report being &amp;quot;unable&amp;quot; to use that runway and would be assigned another runway instead. It is not the responsibility of ATC to ensure that the runway is long enough to land on.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unless there is a NOTAM otherwise noting that a particular exit is unavailable for use, the pilot can slow down at whatever rate to vacate at any particular exit. However, once they've slowed down to taxi speed they should vacate as soon as practicable. The tower controller may request that a pilot vacates at a specific exit, but if they are unable to they will go for another exit.&lt;/p&gt;&#xA;&lt;p&gt;After vacating the runway, the pilot notifies the tower that they are clear of the runway at a particular taxiway, and then will be (depending on the airport) be asked to switch to ground or be given taxi instructions.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="72" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-07T04:13:18.127" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3736" PostTypeId="2" ParentId="3734" CreationDate="2014-05-06T08:31:28.433" Score="6" Body="&lt;p&gt;The approach controller is responsible for assigning the runway to the aircraft, but the pilot of the aircraft is responsible for verifying the runway is long enough for his aircraft and rejecting the approach clearance if he feels it is unsafe. The tower will ultimately give the landing clearance as they have the detailed picture of what is going on at the runway. Note that it is a landing clearance, not an instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower controller can request a runway exit to be used for landing aircraft, however ultimately the pilot is free to choose. If he cannot make an exit or it would require excessive braking a pilot will elect to take a later exit. In general pilots will vacate as soon as practicable not to cause interference with other traffic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft has vacated the runway, the pilot will be given taxi clearances either from the tower controller or from a ground controller on a separate frequency. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-05-06T08:31:28.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3737" PostTypeId="1" AcceptedAnswerId="3738" CreationDate="2014-05-06T12:03:18.780" Score="21" ViewCount="35549" Body="&lt;p&gt;At the beginning of each runway there are some white bars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does number of bars in threshold mean anything?&lt;/p&gt;&#xA;" OwnerUserId="2281" LastEditorUserId="97" LastEditDate="2014-05-10T23:27:41.513" LastActivityDate="2020-03-12T00:26:49.737" Title="What does the number of white bars in runway's threshold mean?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3738" PostTypeId="2" ParentId="3737" CreationDate="2014-05-06T12:18:42.680" Score="30" Body="&lt;p&gt;For runways built, refurbished or repainted after January 2008, the number of bars in the Threshold Markings indicates the width of the runway, as is described in &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0203.html&quot; rel=&quot;noreferrer&quot;&gt;Section 3 of the AIM&lt;/a&gt;. Older runways may still use an outdated scheme.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Runway threshold markings come in two configurations. They either consist of eight longitudinal stripes of uniform dimensions disposed symmetrically about the runway centerline, as shown in FIG 2-3-1, or the number of stripes is related to the runway width as indicated in TBL 2-3-2. A threshold marking helps identify the beginning of the runway that is available for landing. In some instances the landing threshold may be relocated or displaced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xIsA2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xIsA2.png&quot; alt=&quot;Fig 2-3-1&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0203_Auto27.png&quot; rel=&quot;noreferrer&quot;&gt;faa.gov&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;pre&gt;&#xA;Runway Width   | Number of Stripes &#xA;==================================&#xA;60 feet (18 m) | 4&#xA;75 feet (23 m) | 6&#xA;100 feet (30 m)| 8&#xA;150 feet (45 m)| 12&#xA;200 feet (60 m)| 16 &#xA;&lt;/pre&gt;&#xA;&lt;p&gt;With regard to how to tell the difference between Configuration A and B, Advisory &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/8852E94E6586FDD28625700300509565?OpenDocument&amp;amp;Highlight=standards%20for%20airport%20markings&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5340-1J&lt;/a&gt; goes into significantly more detail. It states that&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The threshold markings may have either of the characteristics in (1) or (2) below, but after January 1, 2008, only those characteristics in (2) will be acceptable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The details:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Configuration A.&lt;/strong&gt; The runway threshold marking consists of eight longitudinal stripes of uniform dimensions spaced symmetrically about the runway centerline as shown in Figure 1. The stripes are 150 feet (45 m) long and 12 feet (3.6 m) wide and spaced 3 feet (1 m) apart, except for the center space, which is 16 feet (4.8 m). For runways less than 150 feet (45 m) in width, the length of the markings is not changed, but the width of the markings, spaces between markings and distance of markings from the runway edge are changed proportionally. For runways greater than 150 feet (45m) in width, the width of the markings and spaces between the markings may be increased proportionally or additional stripes may be added to both sides.&lt;/p&gt;&#xA;&lt;p&gt;The rule for Configuration A markings requires scaling the width of the stripes and their spacings (and the outboard spacings from the runway edges) proportionally, keeping the length fixed. For a runway 150 feet wide the Configuration A stripes are 12 ft wide with 3 ft spacings (and an 8 ft spacing from the inboard stripe to the centreline, leaving 10 ft between the outboard and runway edge). The Configuration B stripes are given a fixed width of 5.75 ft with spacings of 5.75 ft also. If a Configuration A scheme were used on a narrow runway such that the stripes were equal to the width of the Configuration B stripes, the runway width would need to be about 72 feet (12 ft stripe width for a 150 ft runway width scaled to 5.75 ft for 71.875 ft). For a 72 ft wide runway bearing the Configuration A scheme the spacing between stripes would be reduced to slightly less than 1.5 ft. The difference between the schemes therefore ought to be apparent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Configuration B.&lt;/strong&gt; For this configuration, the number of stripes required is related to the runway width as indicated in Table 2. The stripes are 150 feet (45 m) long and 5.75 feet (1.75 m) wide and spaced 5.75 feet (1.75 m) apart except the center space is 11.5 feet (3.5 m) as shown in Figure 1. The outboard edges of the outboard stripes extend laterally to within 10 feet (3 m) of the edge of a runway or to a distance of 92 feet (27 m) on either side of a runway centerline, whichever results in the smaller lateral distance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is further borne out by a &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/certalerts/media/cert0404.rtf&quot; rel=&quot;noreferrer&quot;&gt;May 2004 advisory (CERTALERT 04-04)&lt;/a&gt; which states:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The purpose of this CERTALERT is to remind Airport Operators, Airport Certification Safety Inspectors, and Program Managers that paragraph 9(d) states the threshold markings may have either the characteristics in (1) Configuration A or (2) Configuration B, but after January 1, 2008, only those characteristics in (2) Configuration B will be acceptable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-14T08:17:49.620" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="3739" PostTypeId="2" ParentId="3737" CreationDate="2014-05-06T12:18:55.283" Score="8" Body="&lt;p&gt;at the beginning of the runway are Threshold marking which mark where you can touch down&lt;/p&gt;&#xA;&#xA;&lt;p&gt;to quote &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0203.html&quot;&gt;faa.gov&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;h. Runway Threshold Markings.&lt;/strong&gt; Runway threshold markings come in two&#xA;  configurations. They either consist of eight longitudinal stripes of&#xA;  uniform dimensions disposed symmetrically about the runway centerline,&#xA;  as shown in FIG 2-3-1, &lt;strong&gt;or the number of stripes is related to the&#xA;  runway width as indicated&lt;/strong&gt; in TBL 2-3-2. A threshold marking helps&#xA;  identify the beginning of the runway that is available for landing. In&#xA;  some instances the landing threshold may be relocated or displaced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and table 2-3-2 &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; Runway Width      Number of Stripes  &#xA; 60 feet (18 m)    4  &#xA; 75 feet (23 m)    6  &#xA; 100 feet (30 m)   8  &#xA; 150 feet (45 m)   12  &#xA; 200 feet (60 m)   16&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-05-06T12:18:55.283" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3740" PostTypeId="1" AcceptedAnswerId="3742" CreationDate="2014-05-06T12:33:06.257" Score="28" ViewCount="101955" Body="&lt;p&gt;How much reserve fuel are private and commercial aircraft required to carry by ICAO rules? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I heard that it changed recently (about a year ago) and is a little complicated.  How is it calculated for a particular flight? &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-10-11T07:16:34.283" Title="What are the ICAO fuel reserve requirements?" Tags="&lt;flight-planning&gt;&lt;fuel&gt;&lt;icao-sarps&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3741" PostTypeId="1" CreationDate="2014-05-06T13:20:59.280" Score="13" ViewCount="5389" Body="&lt;p&gt;How do the Beech Bonanza's ruddervators work? When the yoke is pulled completely back, is it possible to use rudder?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="22726" LastEditDate="2019-09-14T22:01:46.903" LastActivityDate="2019-09-14T22:01:46.903" Title="How do the Beech Bonanza's ruddervators work?" Tags="&lt;rudder&gt;&lt;v-tail&gt;&lt;beechcraft-bonanza&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3742" PostTypeId="2" ParentId="3740" CreationDate="2014-05-06T13:35:43.570" Score="29" Body="&lt;p&gt;The following includes the changes you allude to (which were proposed in &lt;a href=&quot;http://caa.bg/upload/docs/ANNEX_6_EDTO.pdf&quot;&gt;ICAO State Letter SP 59/4.1-11/8&lt;/a&gt; on June 30, 2011).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Commercial Flights&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Per ICAO Annex 6, Part I, section 4.3.6 &quot;Fuel Requirements,&quot; airplanes should calculate their required fuel quantity as follows (summary; see below for actual ICAO text):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Taxi fuel&lt;/li&gt;&#xA;&lt;li&gt;Trip fuel (to reach intended destination)&lt;/li&gt;&#xA;&lt;li&gt;Contingency fuel (higher of 5% of &quot;trip fuel&quot; or 5 minutes of holding flight)&lt;/li&gt;&#xA;&lt;li&gt;Destination alternate fuel (to fly a missed and reach an alternate)&lt;/li&gt;&#xA;&lt;li&gt;Final reserve fuel (45 minutes of holding flight for reciprocating engines, 30 minutes for jets)&lt;/li&gt;&#xA;&lt;li&gt;Additional fuel (if needed to guarantee ability to reach an alternate with an engine failure or at lower altitude due to a pressurization loss)&lt;/li&gt;&#xA;&lt;li&gt;Discretionary fuel (if the pilot in command wants it)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;General Aviation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For general aviation, ICAO Annex 6 Part II, section 2.2.3.6 &quot;Fuel and oil supply&quot; requires:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For IFR, enough fuel to reach destination, then alternate (if required), plus 45 minutes&lt;/li&gt;&#xA;&lt;li&gt;For day VFR, enough fuel to reach destination plus 30 minutes&lt;/li&gt;&#xA;&lt;li&gt;For night VFR, enough fuel to reach destination plus 45 minutes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;ICAO Annex 6 Part I&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.bazl.admin.ch/experten/regulation/03080/03081/index.html&quot;&gt;ninth edition&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4.3.6.3&lt;/strong&gt; The pre-flight calculation of usable fuel required shall include:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) &lt;em&gt;taxi fuel&lt;/em&gt;, which shall be the amount of fuel expected to be consumed before take-off;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) &lt;em&gt;trip fuel&lt;/em&gt;, which shall be the amount of fuel required to enable the aeroplane to fly from take-off, or the point of in-flight&#xA;  re-planning, until landing at the destination aerodrome taking into account the operating conditions of 4.3.6.2 b);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c) &lt;em&gt;contingency fuel&lt;/em&gt;, which shall be the amount of fuel required to compensate for unforeseen factors. It shall be five per&#xA;  cent of the planned trip fuel or of the fuel required from the point of in-flight re-planning based on the consumption&#xA;  rate used to plan the trip fuel but, in any case, shall not be lower than the amount required to fly for five minutes at&#xA;  holding speed at 450 m (1 500 ft) above the destination aerodrome in standard conditions;&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;&lt;i&gt;Note.— Unforeseen factors are those which could have an influence on the fuel consumption to the destination&#xA;    aerodrome, such as deviations of an individual aeroplane from the expected fuel consumption data, deviations from&#xA;    forecast meteorological conditions, extended taxi times before take-off, and deviations from planned routings and/or&#xA;    cruising levels.&lt;/i&gt;&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;d) &lt;em&gt;destination alternate fuel&lt;/em&gt;, which shall be:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;where a destination alternate aerodrome is required, the amount of fuel required to enable the aeroplane to:&lt;br&gt;&#xA;  i) perform a missed approach at the destination aerodrome;&lt;br&gt;&#xA;  ii) climb to the expected cruising altitude;&#xA;  iii) fly the expected routing;&lt;br&gt;&#xA;  iv) descend to the point where the expected approach is initiated; and&lt;br&gt;&#xA;  v) conduct the approach and landing at the destination alternate aerodrome; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;where two destination alternate aerodromes are required, the amount of fuel, as calculated in 4.3.6.3 d) 1),&#xA;  required to enable the aeroplane to proceed to the destination alternate aerodrome which requires the greater&#xA;  amount of alternate fuel; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;where a flight is operated without a destination alternate aerodrome, the amount of fuel required to enable the&#xA;  aeroplane to fly for 15 minutes at holding speed at 450 m (1 500 ft) above destination aerodrome elevation in&#xA;  standard conditions; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;where the aerodrome of intended landing is an isolated aerodrome:&lt;br&gt;&#xA;  i) for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes plus 15 per cent of the&#xA;  flight time planned to be spent at cruising level, including final reserve fuel, or two hours, whichever is less;&#xA;  or&lt;br&gt;&#xA;  ii) for a turbine-engined aeroplane, the amount of fuel required to fly for two hours at normal cruise&#xA;  consumption above the destination aerodrome, including final reserve fuel;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;e) &lt;em&gt;final reserve fuel&lt;/em&gt;, which shall be the amount of fuel calculated using the estimated mass on arrival at the destination&#xA;  alternate aerodrome, or the destination aerodrome when no destination alternate aerodrome is required:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes, under speed and altitude&#xA;  conditions specified by the State of the Operator; or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;for a turbine-engined aeroplane, the amount of fuel required to fly for 30 minutes at holding speed at 450 m&#xA;  (1 500 ft) above aerodrome elevation in standard conditions;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;f) &lt;em&gt;additional fuel&lt;/em&gt;, which shall be the supplementary amount of fuel required if the minimum fuel calculated in accordance with 4.3.6.3 b), c), d) and e) is not sufficient to:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;allow the aeroplane to descend as necessary and proceed to an alternate aerodrome in the event of engine failure&#xA;  or loss of pressurization, whichever requires the greater amount of fuel based on the assumption that such a failure&#xA;  occurs at the most critical point along the route;&lt;br&gt;&#xA;  i) fly for 15 minutes at holding speed at 450 m (1 500 ft) above aerodrome elevation in standard conditions; and&lt;br&gt;&#xA;  ii) make an approach and landing;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;allow an aeroplane engaged in EDTO to comply with the EDTO critical fuel scenario as established by the State&#xA;  of the Operator;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;meet additional requirements not covered above;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;&lt;i&gt;Note 1.— Fuel planning for a failure that occurs at the most critical point along a route (4.3.6.3 f) 1)) may place&#xA;    the aeroplane in a fuel emergency situation based on 4.3.7.2.&lt;/i&gt;&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;&lt;i&gt;Note 2.— Guidance on EDTO critical fuel scenarios is contained in Attachment D;&lt;/i&gt;&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;g) &lt;em&gt;discretionary fuel&lt;/em&gt;, which shall be the extra amount of fuel to be carried at the discretion of the pilot-in-command.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;ICAO Annex 6 Part II&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;2.2.3.6&lt;/strong&gt; Fuel and oil supply&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A flight shall not be commenced unless, taking into account both the meteorological conditions and any delays that are&#xA;  expected in flight, the aeroplane carries sufficient fuel and oil to ensure that it can safely complete the flight. The amount of&#xA;  fuel to be carried must permit:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) when the flight is conducted in accordance with the instrument flight rules and a destination alternate aerodrome is&#xA;  not required in accordance with 2.2.3.5, flight to the aerodrome of intended landing, and after that, for at least 45&#xA;  minutes at normal cruising altitude; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) when the flight is conducted in accordance with the instrument flight rules and a destination alternate aerodrome is&#xA;  required, flight from the aerodrome of intended landing to an alternate aerodrome, and after that, for at least 45&#xA;  minutes at normal cruising altitude; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c) when the flight is conducted in accordance with the visual flight rules by day, flight to the aerodrome of intended&#xA;  landing, and after that, for at least 30 minutes at normal cruising altitude; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d) when the flight is conducted in accordance with the visual flight rules by night, flight to the aerodrome of intended&#xA;  landing and thereafter for at least 45 minutes at normal cruising altitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-05-06T14:27:38.100" LastActivityDate="2014-05-06T14:27:38.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3743" PostTypeId="2" ParentId="3740" CreationDate="2014-05-06T16:12:19.763" Score="0" Body="&lt;p&gt;Fuel &amp;amp; oil (propeller –driven A/c)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A) When a destination alternate is required&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B) When destination aerodrome is VMC /alternate not required&lt;/p&gt;&#xA;&#xA;&lt;p&gt;C) When a destination is isolated and no suitable destination alternate is available &lt;/p&gt;&#xA;&#xA;&lt;p&gt;i. Fuel to destination ………. A&#xA;(includes one approach and a missed approach)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ii. + fuel is specified diversion ……….B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;iii. + 45 mts&#xA;i.e A+B+45 mts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i. Fuel to destination …. A&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ii. +45 mts&#xA;i.e A+45 mts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i. Fuel to destination …. A&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ii. + 45 mts+15 5 of cruising time or 2 hrs ….B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which is less&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e A+B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel &amp;amp; oil (Turbo jets)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A. When a destination alternate is required&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel destination including an approach and a missed approach ...A &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel to alternate aerodrome as specified in flights plan …B&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;30 mts holding at 1500’ at holding speed above alternate aerodrome in ISA&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Approach&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;land&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Additional contingency fuel as specified by operator …C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e A+B + 30 mts holding at 1500’ +approach + landing fuel +C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B. When a destination alternate is not required because destination is VMC&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel to destination + 30 mts holding fuel at 1500’ above the aerodrome destination at holding speed in ISA …. B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional contingency fuel as specified by operator …C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e A+B+C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;C. When destination is isolated and no suitable destination alternate aerodrome is available &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel to destination + 2 hrs fuel at normal fuel cruise consumption …. B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e A+B&lt;/p&gt;&#xA;" OwnerUserId="2283" LastEditorUserId="2283" LastEditDate="2014-05-06T16:49:01.383" LastActivityDate="2014-05-06T16:49:01.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3744" PostTypeId="2" ParentId="3741" CreationDate="2014-05-06T16:42:45.467" Score="10" Body="&lt;p&gt;In the Bonanza, a mechanical mixer controls ruddervator movement based on pitch and yaw commands. Here's a typical V-tail mixer (this is not of a Bonanza though):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dHLin.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dHLin.jpg&quot; alt=&quot;Fouga Magister V-tail mixer &amp;amp; linkage&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.eaa1000.av.org/pix/fouga/mixer.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;eaa1000.av.org&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;There are two rods extending off to the left of this photo that connect to the actual ruddervators. Rightward motion of the top rod (due to either rightward motion of the entire mixer assembly due to a pitch command, or clockwise rotation of the assembly due to a yaw command) will deflect the ruddervator one direction; leftward motion deflects it the other direction. Similar for the other ruddervator connected at the bottom.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;I can't completely answer the second part of your question&lt;/strong&gt;, whether yaw authority is reduced when pitching or vice versa. It depends on where the limit stops are installed in a Bonanza. If the stops are set on the ruddervator side (left side in photo above, so that the mixer's range of motion is limited by its leftward connections), the amount of available rudder will be reduced when pitching. (Sorry I can't answer that part of the question, but I thought the information about the mixer would still make a useful answer.)&lt;/p&gt;&#xA;&lt;p&gt;The airplane is obviously designed so that sufficient authority is available in all situations. (This means making the two fins of the V longer than those of a traditional horizontal/vertical stabilizer design so that similar control surface area is available.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-15T21:16:08.370" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3745" PostTypeId="1" CreationDate="2014-05-06T16:53:08.100" Score="10" ViewCount="5120" Body="&lt;p&gt;How is the difference between Commercial and Private/General Aviation flights defined by ICAO?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here in the US, we use 91 flights -vs- 135 flights, but from what I've heard they use a different definition, particularly concerning business aviation flights that fall under Part 91.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, what determines whether ICAO Annex 6 &lt;em&gt;Part 1&lt;/em&gt; or &lt;em&gt;Part 2&lt;/em&gt; applies to a particular flight?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-10-14T11:28:16.490" LastActivityDate="2018-01-29T16:56:57.430" Title="How does ICAO differentiate between Commercial and Private flights?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3746" PostTypeId="2" ParentId="3734" CreationDate="2014-05-06T17:13:37.803" Score="1" Body="&lt;p&gt;The Tower controls the runways and therefore designates active runways for arriving and departing traffic.  Typically this is done based on current surface winds and aircraft type.&lt;/p&gt;&#xA;" OwnerUserId="651" LastActivityDate="2014-05-06T17:13:37.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3747" PostTypeId="2" ParentId="3741" CreationDate="2014-05-06T17:57:31.257" Score="8" Body="&lt;p&gt;A paragraph in &lt;em&gt;&lt;a href=&quot;http://www.beechcraft.org/vtail/eckalbar/rudder.html&quot;&gt;Flying the Beech Bonanza&lt;/a&gt;&lt;/em&gt; explains the ruddervator operation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The following facts from the Shop Manual for the V35B illustrate how&#xA;  the control mixer and ruddervator stops allow differential ruddervator&#xA;  displacement. With full up elevator and no rudder input, the left&#xA;  ruddervator will be 22 1/2 degrees up. With full right rudder and&#xA;  elevator neutral, the left ruddervator will be 23 degrees up. And with&#xA;  full up elevator and right rudder simultaneously, the left ruddervator&#xA;  will be 44 degrees up. By contrast, the elevator of the A36 is limited&#xA;  to 23 degrees up and 20 degrees down, while the rudder is limited to&#xA;  25 degrees left or right.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; On the Beech Bonanza, the yaw and pitch inputs are added, so that full back on the yoke gives about 22 degrees of ruddervator, and adding full right rudder would add 22 more degrees for a net result of 44 degrees up of ruddervator on the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that the other ruddervator would be at 22 degrees up, though of this I am not sure.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-05-06T17:57:31.257" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3748" PostTypeId="1" AcceptedAnswerId="3756" CreationDate="2014-05-06T18:16:35.443" Score="20" ViewCount="6223" Body="&lt;p&gt;Why do airlines separate passengers into 1st and 2nd class but do not offer fast or slow connections? Isn't the biggest cost the kerosene? And isn't the cost directly proportional to speed?&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="97" LastEditDate="2014-05-06T21:00:07.260" LastActivityDate="2014-10-13T07:58:55.443" Title="Why 1st and 2nd class but not fast or slow airplanes?" Tags="&lt;airline-operations&gt;&lt;aircraft-performance&gt;&lt;cost&gt;" AnswerCount="10" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3749" PostTypeId="2" ParentId="3748" CreationDate="2014-05-06T18:27:07.480" Score="15" Body="&lt;p&gt;The optimal speed of the aircraft is set by the manufacturer. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;isn't the cost directly proportional to speed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, any speed above or below the optimal one will lead to sub-optimal performance of the engine, increasing the costs.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why airlines do not offer fast or slow connections?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer is partial speculation, but the costs do not increase linearly, and I think that the people that could afford such increase in costs (and would buy such a ticket) are not enough to fill standard commercial aircrafts. In fact I think they have their own personal and private business-jet (or something of this sort)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-05-06T18:27:07.480" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3750" PostTypeId="2" ParentId="3748" CreationDate="2014-05-06T18:44:34.247" Score="22" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Concorde&quot;&gt;Concorde&lt;/a&gt; was built for speed. But it was costly too. People did not like it much. Reality was that they didn't want to get somewhere faster by paying more. People love to pay for luxury though. That is the reason different &lt;a href=&quot;http://en.wikipedia.org/wiki/Travel_class&quot;&gt;travel classes&lt;/a&gt; were introduced since late 1970s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cost of fuel and speed are NOT directly related. As you may know, Boeing 787 has increased fuel efficiency (claimed to be the most fuel-efficient), and still reaching higher speeds.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-05-06T18:44:34.247" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="3751" PostTypeId="2" ParentId="2822" CreationDate="2014-05-06T21:19:00.807" Score="4" Body="&lt;p&gt;Not going by Barra Airport - &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Barra Airport is famous for its beauty - boasting beaches, machair and hills - and all in a small island; Barra is a special place to visit - especially memorable if you fly in because of the beach landing strip. Washed by the tide twice a day, &lt;strong&gt;Traigh Mhor beach is reputed to be the only beach runway in the world to handle scheduled airline services&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;See &lt;a href=&quot;http://www.hial.co.uk/barra-airport/airport-information/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Barra Airport website&lt;/a&gt; &#xA;&lt;img src=&quot;https://i.stack.imgur.com/LdWtj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1715" LastEditorUserId="19" LastEditDate="2016-07-05T06:42:57.503" LastActivityDate="2016-07-05T06:42:57.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3752" PostTypeId="2" ParentId="3748" CreationDate="2014-05-06T22:14:26.547" Score="1" Body="&lt;p&gt;There is indeed a benefit in flying more slowly, but the aircraft needs to be designed that way to profit from slower speeds. You can see that wing sweep has been slightly reduced in the more modern airliners, but this is also due to better airfoils with higher Mach drag rise onset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But some things will also cost more when you slow down: You have to pay the crew for more hours, and the aircraft cannot be utilized as often. To transport the same number of passengers requires more aircraft when they fly at a lower speed. The cost versus speed relationship is not linear, but it should have a minimum somewhere below today's operating points. Aircraft with a slower design cruise speed can be lighter and smaller for the same payload, but for now airlines don't have a choice of slow or fast jets; all manufacturers try to fly at least Mach 0.83.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has a lot to do with marketing: The aircraft with the higher speed will show a shorter travel time for the same distance, so it will show up first in the booking systems of travel agents. Of course, now you will argue that most people book on the internet and will try to get the lowest cost, regardless of travel time. True. But this is not the sort of customer the airlines are after. Their profit comes from people in First and Business class, and these still book predominantly via travel agents. Therefore, Airbus and Boeing try to market their planes as the ones which come first on the Amadeus and Sabre screens.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-06T22:14:26.547" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3753" PostTypeId="2" ParentId="3748" CreationDate="2014-05-07T02:58:24.647" Score="7" Body="&lt;p&gt;Providing a fast and a slow &quot;class&quot; for flight tickets would add a lot of overhead to airline operation in many ways  - way more than it could be worth it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To have fast and slow flights, one could&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Use two kinds of planes, fast and slow:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Requires big, slow planes and fast, smaller planes, assuming fewer seats are sold in the fast, expensive class. An airline that has only one size of planes now would &lt;strong&gt;require a broad range of types&lt;/strong&gt; of planes.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Cannot handle&lt;/strong&gt; flights that now use relatively &lt;strong&gt;small&lt;/strong&gt; planes when the fraction of fast-class passengers is low, as for very few it get's just too ineffective to have a separate flight.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The potential solution of downgrading the high-price customers to slow flights does not sound useful. &lt;/li&gt;&#xA;&lt;li&gt;Solving it by upgrading the slow-class passengers to a fast flight does not work in general as the fast planes needed otherwise are too small for the higher count of passengers (or would at least make planning even harder).   &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Use one kind of plane, used to fly fast or slow:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Needs about &lt;strong&gt;twice as many&lt;/strong&gt; planes compared to now.&lt;/li&gt;&#xA;&lt;li&gt;Makes seat allocation planning harder - need to estimate counts per speed class for planning, which may change depending on external events (like trade fairs at destination being consumer or business-targeted)&lt;/li&gt;&#xA;&lt;li&gt;Will provide &lt;strong&gt;not much benefit&lt;/strong&gt; to the passenger, as the difference between the fast and the slow flight speed is limited by the physics of the planes used&lt;br&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The slow speed would need to be the most fuel-effective speed, to support low prices. That is the speed of &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift-to-drag_ratio&quot;&gt;best L/D ratio&lt;/a&gt; - so the slow speed could not be much slower that today's standard speed, as that would cost extra fuel. &lt;/li&gt;&#xA;&lt;li&gt;The fast speed would be limited by the highest speed of the plane allowing acceptable fuel use, and by the power that the engines of the airplane can provide (assuming it's save to fly at that speed).&lt;br&gt;&#xA;Because the fast-class speed is faster than the slow-class speed, it's above the speed of best L/D ratio. For speeds in that range, the induced drag is dominated by the form drag, and the from drag increases with the square of the speed.&#xA;At some speed, looking at total fuel usage it does no longer make economic sense to go faster, and because of the square relation, I expect the &lt;strong&gt;possible speed difference&lt;/strong&gt; to be &quot;not large enough to make sense&quot; to distinguish two completely different flight classes.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;It could work, though, if we take large &lt;strong&gt;airships&lt;/strong&gt; into account, and providing very slow, but very cheap flights, but still faster that water-based ships.&lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="1875" LastEditDate="2014-05-07T10:28:52.873" LastActivityDate="2014-05-07T10:28:52.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3754" PostTypeId="1" AcceptedAnswerId="3760" CreationDate="2014-05-07T03:04:48.767" Score="26" ViewCount="59377" Body="&lt;p&gt;A two part question this time, though they are closely related enough that I figured I'd knock them out all at once.  I figure the first question probably informs the second question anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, how does a jet engine flip over to reverse thrust?  I'm assuming the turbine doesn't actually switch directions.  Is there a set of blades towards the rear of the engine that divert the flow forward again?  How's that work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Probably more topically:  When is the right time to apply reverse thrust?  I'm assuming you ought to be on the ground (that seems like a given), but are there checks that a pilot has to do before engaging the reverse thrust?  Are there times when it's not used, or when it possibly just isn't necessary?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2018-03-19T13:59:13.623" LastActivityDate="2018-06-06T09:44:26.977" Title="How does thrust reversal work on a jet engine, and when should it be used?" Tags="&lt;jet-engine&gt;&lt;landing&gt;&lt;thrust-reverser&gt;&lt;aircraft-heavy&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3755" PostTypeId="2" ParentId="3754" CreationDate="2014-05-07T05:47:22.963" Score="7" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_reverser&quot; rel=&quot;noreferrer&quot;&gt;Thrust reverser&lt;/a&gt;: There are a number of types, ranging from bucket reversers that swing a pair of doors into the exhaust stream, directing it forward, to door-based systems that direct the bypass air of a high-bypass turbofan engine out the sides of the engine in a somewhat forward direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases, you want to apply reverse thrust as soon as the wheels are on the ground.  Some aircraft can use in-flight thrust reversal for a quick reduction of speed or altitude, but these tend to be military aircraft that need the improved performance.  You want to &lt;em&gt;stop&lt;/em&gt; using reverse thrust as soon as you're going slowly enough that any debris kicked up could make its way into the engine intake, which is why airplanes mostly don't use reverse thrust for backing up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a special case, turboprop engines can twist the propeller blades so that the normal rotation of the propeller pushes air forwards rather than back, but you may not consider these to be &quot;jet&quot; engines.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="100" LastEditDate="2014-05-07T09:34:32.530" LastActivityDate="2014-05-07T09:34:32.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3756" PostTypeId="2" ParentId="3748" CreationDate="2014-05-07T09:08:00.220" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;isn't the cost directly proportional to speed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Most fuel can be saved by flying &lt;em&gt;higher&lt;/em&gt; because the lower air density reduces parasite drag. Provided the trip is long enough for the saving at altitude to offset the cost of getting there.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft drag has two components. The parasite drag which increases with speed and the induced drag which decreases. So they have a point of minimum drag and for jet airliners it's typically somewhere between 200 and 250 knots &lt;em&gt;indicated&lt;/em&gt;. Flying any slower would increase the cost. At the altitude where jets normally fly, the true speed is significantly higher than indicated speed.&lt;/li&gt;&#xA;&lt;li&gt;For jet engines, the fuel burned is roughly proportional to &lt;em&gt;thrust&lt;/em&gt; they generate and at higher thrust &lt;em&gt;lower&lt;/em&gt; per unit of thrust. Since power is thrust times speed, this translate to much better efficiency at higher speed. So a jet wants to fly slightly faster than their lowest drag point.&lt;/li&gt;&#xA;&lt;li&gt;Even if the trip cost is higher, higher speed allows you to make more trips, so the fixed costs get split over more passengers. So it makes sense to fly slightly faster than the lowest fuel burn.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Generally airliners are operated at the point of lowest cost. For long trips where it pays off to climb high, jets are most efficient. For short trips, turboprops are often used that can't climb that high, but are more efficient at lower altitudes and speeds.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-10-13T07:56:55.303" LastActivityDate="2014-10-13T07:56:55.303" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3757" PostTypeId="2" ParentId="3748" CreationDate="2014-05-07T11:02:23.990" Score="2" Body="&lt;p&gt;To offer different rates for different speed of travel the airline would need to add different aircraft types to their fleet, which would increase their cost of doing business dramatically.&lt;br/&gt;&#xA;They'd need to have a slow type for the lower price, a medium speed type for the &quot;regular&quot; price, and a fast type for the &quot;high speed rate&quot;.&lt;br/&gt;&#xA;If those even exist in the range/size bracket the airline is planning to introduce that service in, they'd now have to have multiple groups of crews, several more maintenance facilities with crews trained in maintenance of different aircraft types, a vastly increased amount of parking space for storing the aircraft in between missions, massively increased spare parts inventory, etc. etc. etc..&lt;br/&gt;&#xA;All that would mean the cost of running the scheme would rapidly overshadow the potentially higher income. And at the same time the customers would run away from the lower speed option to take the train of fly with a competitor who offers the same route on a faster aircraft using a more traditional service based pricing policy.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-05-07T11:02:23.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3758" PostTypeId="2" ParentId="2458" CreationDate="2014-05-07T11:17:13.190" Score="6" Body="&lt;p&gt;The &lt;strong&gt;wear and tear&lt;/strong&gt; of the runway depends very strongly on the &lt;strong&gt;weight of aircrafts&lt;/strong&gt;, so I expect it to be at least taken into account. By &lt;strong&gt;discussing the physics&lt;/strong&gt; of this below, I will show that the effect is &lt;strong&gt;stronger than intuition&lt;/strong&gt; may commonly suggest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is certainly not the only factor to determine the fee, and may even be a minor one in most cases, but it could be of practical importance for more uncommon cases, (like when a runway is already in bad shape in some way). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll do a rough estimate of the incremental damage caused by a plane, on average, in comparison to planes of different weight.&lt;br&gt;&#xA;The wear of the runway and taxiways depend on the load per area that is caused by the wheels. Take note that heavier planes use larger wheels to reduce that load per area.&lt;br&gt;&#xA;Regarding the basic physics, the load per area is comparable to the axle load of cars. For the street wear caused by a car, this article [1] states that it is proportional to the axle load raised to the fourth power.&lt;br&gt;&#xA;That means a double load per area causes 16 times the wear, or four times load per area 256 times the wear.&lt;br&gt;&#xA;Even without an estimate of how much reduction of the load per area is provided by using larger wheels, I think that means that, for all &lt;strong&gt;practical purposes&lt;/strong&gt;, the wear is caused &lt;strong&gt;only by the &quot;large&quot; airplanes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1]: &lt;a href=&quot;http://www.fuks.org/fileadmin/download/transfer/kt34/2-KT34-verkehr.pdf&quot; rel=&quot;nofollow&quot;&gt;&quot;Die Kosten der Verkehrsinfrastruktur&quot; Page 12 (German, PDF)&lt;/a&gt; refering to work of the american State Highway and Transportation Officials (AASHO) during the 1950ies, see &lt;a href=&quot;https://de.wikipedia.org/wiki/Achslast&quot; rel=&quot;nofollow&quot;&gt;Wikipedia (German) on axle load&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="1875" LastEditDate="2014-06-17T18:56:11.650" LastActivityDate="2014-06-17T18:56:11.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3759" PostTypeId="1" AcceptedAnswerId="3762" CreationDate="2014-05-07T14:38:03.547" Score="25" ViewCount="8884" Body="&lt;p&gt;Let's say somebody charters a small airplane from Canada and flies into the US (after receiving clearance from the US ATC). After crossing the border, they land on a small airstrip in the middle of nowhere instead of going to an airport with a customs facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would anything stop them from doing so? Would the police be notified immediately by the ATC? Is all international air traffic closely monitored until they pass through customs?&lt;/p&gt;&#xA;" OwnerUserId="2172" LastActivityDate="2014-05-19T14:44:12.647" Title="What stops an international private airplane from landing outside of airports with a customs zone?" Tags="&lt;international&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3760" PostTypeId="2" ParentId="3754" CreationDate="2014-05-07T14:38:14.933" Score="28" Body="&lt;p&gt;The engine does not move, the air flow is only redirected. The method of redirecting the flow varies with the size, configuration, and manufacturer of the engine. The flow does not need to be directed completely forward; the flow is generally mostly outwards and partially forward. This is still enough to create significant drag and slow the aircraft down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In smaller and older engines, the entire flow is redirected. This corresponds to the first two configurations below. Buckets or clamshell doors close over the jet flow to redirect the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In larger engines, particularly high-bypass turbofans, only part of the air is redirected. This corresponds to the last configuration below. The core air from the engine still exits normally, but the bypass air from the fan is redirected. Since the bypass air on these engines is a much greater flow than the engine core air, this results in a net reverse thrust. There are multiple mechanisms, but the general idea is to deploy doors that block the bypass air and send it through the sides of the engine cowl.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turboprop aircraft just change the pitch of the propeller blades such that the propeller pushes air forward instead of backward. The pitch in which the blades provide reverse thrust is called the &quot;beta range.&quot;&#xA;&lt;hr&gt;&#xA;In civil aircraft, reverse thrust is only used when on the ground. There are typically interlocks in the system that prevent the thrust reversers from deploying if the aircraft does not sense that it is on the ground. Once the aircraft touches down, the pilot will deploy the reverse thrust. Some military aircraft like the C-17 can use reverse thrust in the air. This enables them to perform very steep descents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reverse thrust is more of an &quot;optional&quot; method of braking (see this &lt;a href=&quot;https://aviation.stackexchange.com/questions/1219/for-large-jets-what-is-the-primary-means-of-slowing-down-after-landing&quot;&gt;related question&lt;/a&gt;), only to provide extra stopping power when needed. This particularly helps when braking force is less effective, such as in rain or snow. Before landing, pilots will take into account the wind, aircraft weight, runway length, and any contamination of the runway (rain or snow). Based on this they will know what kind of braking force is needed and whether they should use thrust reversers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust reversers don't always have to be operational for an aircraft to fly. Some operators choose to disable them, which decreases maintenance costs. The thrust reversers can also break, in which case they will be mechanically locked to prevent them from deploying until they can be fixed. Pilots will consider this when they are computing their landing distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z5naU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z5naU.jpg&quot; alt=&quot;Reverse thrust methods&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="753" LastEditDate="2018-03-15T18:54:46.213" LastActivityDate="2018-03-15T18:54:46.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3761" PostTypeId="2" ParentId="3759" CreationDate="2014-05-07T14:50:29.503" Score="14" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Nothing would stop them from doing this unless someone dropped a dime on this flight with credible evidence that this would happen.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes police or the DEA would be notified.  This is the profile of a drug smuggler.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you act like a drug smuggler, expect to be treated like a drug smuggler.  Is all traffic scrutinized?  I cannot confirm that all traffic is so closely monitored.  But much of it is.  Currently there has been more than a few encounters with local police notified by the CBP for &quot;suspicious&quot; flight between California and points east with no border crossing and no probable cause.  These flights have been met with up to a dozen officers with arms drawn.  Illegal stops, IMHO but I am no lawyer.  So if they stop a plane after it flew from San Diego to Albuquerque (as one example) it is highly likely that they would meet a plane that diverted to a different destination than it had filed for, coming in from Mexico or Canada.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-05-19T14:44:12.647" LastActivityDate="2014-05-19T14:44:12.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3762" PostTypeId="2" ParentId="3759" CreationDate="2014-05-07T15:08:13.683" Score="19" Body="&lt;p&gt;It is usually required to file a flight plan for international flights (with very few exceptions), and I'll assume this is the case for Canada/US as well, but I'm not 100% sure of this. In this case you have two options&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You close your flight plan and let ATC or FSS know where you are, they'll note it's an international flight that landed somewhere without customs, and you're likely to end up in trouble.&lt;/li&gt;&#xA;&lt;li&gt;You don't close your flight plan, and you'll trigger a search-and-rescue operation as you'll eventually be overdue, drawing attention to yourself, and you're equally likely to end up in trouble. Not to mention that you'll probably be liable for the cost of the search-and-rescue.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You could of course file a plan with a drastically reduced TAS, do a very quick stop, and arrive at the original destination within the grace period. I don't know if that will trigger any surveillance systems though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't file a flight plan and cross the border anyway, I'm guessing that you will indeed trigger some alerts though.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-05-07T15:21:11.073" LastActivityDate="2014-05-07T15:21:11.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3764" PostTypeId="2" ParentId="3745" CreationDate="2014-05-07T16:54:13.030" Score="3" Body="&lt;p&gt;According to ICAO &lt;strong&gt;Annex 6 Part 1&lt;/strong&gt; (&lt;a href=&quot;http://code7700.com/pdfs/icao_annex_6_part_i.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PDF&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Standards and Recommended Practices contained in Annex 6, Part I,&#xA;  shall be applicable to the operation of aeroplanes by operators&#xA;  authorized to conduct international commercial air transport&#xA;  operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to ICAO &lt;strong&gt;Annex 6 Part 2&lt;/strong&gt; (&lt;a href=&quot;http://code7700.com/pdfs/icao_annex_6_part_ii.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PDF&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;International general aviation operations with:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) aeroplanes with a maximum certificated take-off mass exceeding&#xA;  5,700 kg; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) aeroplanes equipped with one or more turbojets engines.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The International Flight Plan form also requires flight type to be declared, but I am not sure that this would be ICAO's sole requirement.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Type of flight—Indicate which one:&#xA;&#xA;S—Scheduled air transport&#xA;N—Non-scheduled air transport&#xA;G—General aviation&#xA;M—Military&#xA;X—Other&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For a simpler explanation, this &lt;a href=&quot;http://www.icao.int/Meetings/STA10/Documents/Sta10_Wp007_en.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PDF&lt;/a&gt; lists civil aviation activities:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UXQ0u.gif&quot; alt=&quot;ICAO&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.iaopa.eu/what-is-general-aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;page&lt;/a&gt; contains a table (at the bottom) classifying each type.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-07T19:03:27.470" LastActivityDate="2014-05-07T19:03:27.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3766" PostTypeId="1" CreationDate="2014-05-07T19:31:35.917" Score="31" ViewCount="1081" Body="&lt;p&gt;Some students learn best when they can see aerodynamic principles in action. I'd really like to be able to show a student how a spin occurs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there a way to make a paper airplane that will enter a developed spin?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2015-07-10T03:17:40.650" LastActivityDate="2020-03-13T19:00:46.027" Title="Is it possible to build a paper airplane that will enter a fully developed spin?" Tags="&lt;aerodynamics&gt;&lt;spins&gt;&lt;paper-airplane&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3767" PostTypeId="2" ParentId="3766" CreationDate="2014-05-07T20:36:53.293" Score="4" Body="&lt;p&gt;I don't know if this will work for you, but I used to put little tears towards the body on the leading edge of the paper airplanes I made.  Then I'd bend the leading edge of the wing down a bit to create a stronger airfoil.  I'd do this simply to increase lift at low speed, kind of like slats.  But I wonder, if you put a tear on only one side and adjusted it properly, perhaps you could make it so that one wing stalls out before the other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, perhaps to be a bit more accurate, you could just go with tears on both sides but adjust one down further than the other.  That way it's pretty apparent that on wing is developing more lift at low speed.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-05-07T20:36:53.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3768" PostTypeId="2" ParentId="3748" CreationDate="2014-05-07T20:56:07.870" Score="1" Body="&lt;p&gt;Gravity * time aloft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because a heavier-than-air craft must expend a constant amount of energy just to stay aloft* per unit of time, it maximizes efficiency in a trip of given length by minimizing the amount of time required to complete that trip.  This is of course balanced against other factors, but it appears to dominate within any given set of parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Of course, there are more and less efficient ways to do this.  Rocket-hovering is awful, and flying by airfoil at the best L/D ratio for a particular design is great.  Watch an F-14's efficiency go to zero as its constant-altitude airspeed goes to zero.  It is possible to &lt;em&gt;waste&lt;/em&gt; copious amounts of energy on heat and noise, but you cannot counteract more than gravity's constant pull without rising.&lt;/p&gt;&#xA;" OwnerDisplayName="user2298" LastActivityDate="2014-05-07T20:56:07.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3769" PostTypeId="2" ParentId="3703" CreationDate="2014-05-08T02:32:41.793" Score="11" Body="&lt;p&gt;&lt;a href=&quot;http://www.ejectionsite.com/&quot;&gt;I particularly like this site&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is it like ejecting out of a plane at 500 knots? 1000?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Look for this story on the linked site... A USAF F-15 crew ejected, at night, estimated well over mach 1. The back seater was killed in the ejection; the pilot survived; wreaked havoc on his musculoskeletal system and required the lower part of one leg to be amputated but eventually returned to flying status.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As a fighter pilot, would you ever get a practice run ejecting out of a plane&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My experience in a ejection trainer, much like the &quot;air force training rig&quot; above, gave a very short initial jolt equivalent to the real thing. I had my head bent ever so slightly and I had a sore neck for weeks. There was never a repeat ride in our year long training. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ejecting out of the real thing for training? We would have called that sort of thing &quot;practice bleeding&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2014-05-08T02:32:41.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3770" PostTypeId="2" ParentId="3748" CreationDate="2014-05-08T05:18:48.157" Score="3" Body="&lt;p&gt;In thinking about it, the 1st, 2nd and 3rd class distinction originally arose in the time of watercraft travel and during those days, there were also significant distinctions in the speed/cost tradeoffs on various types of vessels. Hence the term, &quot;slow boat to China.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slowest and cheapest passage was to ride supercargo (literally above the cargo) on the slowest cargo vessels such as barges. The fastest and and sometimes most expensive expensive passages were on packet ships, ships built for raw speed and used to carry mail. They were small, cramped and took a pounding from the sea. People seldom took passage on them if they didn't have to. When you read a historical reference to someone important coming in a packet ship, it would be like flying in a VIP in the rear seat of fighter jet today. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The classes came from accommodations and might have come from the British practice of rating ships themselves, 1st, 2nd and 3rd class. They really only appear in the steamship era when purpose built passenger ships evolved. Ocean liners made a point of their speed, sometimes beating packet ships because of their long hulls, but since even a short trip was matter of weeks accommodations mattered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why didn't the air travel industry break down into slow and fast planes? Others have noted the scaling problems with speed vs cost but another major reason is the difficulty in accommodating aircraft flying at different speeds at the same airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The length and strength of runway, for example, has to be proportional to the weight and takeoff/landing speed of the aircraft that use it. A slow light plane on long,strong runway is a waste and the opposite impossible. Likewise, it's hard to safely coordinate planes all flying around at different speeds with different safety intervals. That's why we have the distinction between military, commercial and civil aviation airports, each supports a different array of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrast that with ships in smaller vessels and larger ones skim right by each other (at least at lower harbor speeds.) Harbors used to be crammed with all sizes and speeds of vessels sailing safely by each other and that in turn meant there was an economic niche for both fast/expensive and slow/cheap passage rates. &lt;/p&gt;&#xA;" OwnerUserId="2300" LastActivityDate="2014-05-08T05:18:48.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3771" PostTypeId="2" ParentId="3748" CreationDate="2014-05-08T07:28:02.827" Score="1" Body="&lt;p&gt;There is a faster option - it's a case of looking at total travel time - door to door. In which case private jet is faster.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It goes when you want it to - no waiting for the 747 or A380 to go once a day - saving up to 12 hrs on journey&lt;/li&gt;&#xA;&lt;li&gt;No checkin - minimal formalities (esp if you e.g. head of state) - saving 1hr or more?&lt;/li&gt;&#xA;&lt;li&gt;It goes direct to the nearest airport the aircraft can access. No going via super hubs like Chicago or Heathrow. Saving 3+ hours.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Flying super fast between hubs doesn't save that much time compared to aircraft flying direct to where you want.&lt;/p&gt;&#xA;" OwnerUserId="2301" LastEditorUserId="1467" LastEditDate="2014-05-08T07:57:53.297" LastActivityDate="2014-05-08T07:57:53.297" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3772" PostTypeId="2" ParentId="3759" CreationDate="2014-05-08T09:03:36.743" Score="11" Body="&lt;p&gt;When considering flying an aircraft across the U.S. border, you also have to consider that there is extensive radar coverage of all airspace within the U.S., with varying flight ceilings for different classes of aircraft. Monitored not just by the FAA, but also the Department of Homeland Security and the Department of Defense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This isn't just a safety issue of resolving conflicting flight paths, maintaining air corridors, managing airport capacities, and avoiding collisions. This is also an issue of safeguarding national boundaries and preventing smuggling and terrorism by tracking authorized and unauthorized entries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Entering the country by crossing into its airspace without filing a valid flight plan and having a valid visa/proof of citizenship would constitute a crime of illegal entry. Landing in an out of the way location without a valid customs zone could be construed as trying to avoid registering your presence to the U.S. government, declaring imported goods, paying taxes, or a more nefarious purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The worst case scenario, depending on what the current DHS security level is, could result in you picking up an escort of F-16s to take you to a secured airfield where federal agents will take you into custody, do an extensive full body cavity search, grill you to the nth degree as to your origins and purpose, and detain you for prosecution on any number of charges that are based on what they dig up on you. And don't forget that the NSA has been collecting a vast amount of information on everybody.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Department of Homeland Security U.S. Customs and Border Protection: &lt;a href=&quot;http://www.cbp.gov/travel/pleasure-boats-private-flyers&quot; rel=&quot;noreferrer&quot;&gt;Pleasure boats and private flyers&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2303" LastEditorUserId="97" LastEditDate="2014-05-10T23:32:09.190" LastActivityDate="2014-05-10T23:32:09.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3774" PostTypeId="1" AcceptedAnswerId="3775" CreationDate="2014-05-08T13:51:47.247" Score="1" ViewCount="1265" Body="&lt;p&gt;Does a &lt;a href=&quot;http://en.wikipedia.org/wiki/Walkalong_glider&quot; rel=&quot;nofollow&quot;&gt;walkalong glider&lt;/a&gt; stay aloft because of ground effect (caused by the paddle), or for some other reason?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-05-08T14:31:45.993" Title="Are walkalong gliders based on the principles of ground effect?" Tags="&lt;glider&gt;&lt;paper-airplane&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3775" PostTypeId="2" ParentId="3774" CreationDate="2014-05-08T14:19:51.040" Score="5" Body="&lt;p&gt;No the paddle acts as an inverted wing and pushes air up, this in turn will push the glider up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with ground effect a non-powered glider cannot maintain height and speed.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-05-08T14:19:51.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3776" PostTypeId="2" ParentId="3774" CreationDate="2014-05-08T14:31:45.993" Score="4" Body="&lt;p&gt;The glider is just a glider.  The paddle generates lifting force, essentially creating a moving updraft underneath the glider, which keeps it in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground effect reduces drag, but doesn't create lift.  As ratchet freak mentioned, ground effect alone is not enough to keep a glider in the air indefinitely.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-05-08T14:31:45.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3777" PostTypeId="1" AcceptedAnswerId="3778" CreationDate="2014-05-08T15:17:22.753" Score="7" ViewCount="4210" Body="&lt;p&gt;What is the difference between a cold-stream thrust reverser and a conventional one? It seems that all engines emit hot air, due to the combustion process.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2019-02-05T22:31:51.133" Title="What is the difference between a cold-stream thrust reverser and a conventional one?" Tags="&lt;thrust-reverser&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3778" PostTypeId="2" ParentId="3777" CreationDate="2014-05-08T15:23:14.703" Score="11" Body="&lt;p&gt;Turbofan engines don't push all air through the combustion chamber. Instead part of it runs along the sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/File:Turbofan3_Labelled.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/Turbofan3_Labelled.gif/300px-Turbofan3_Labelled.gif&quot; alt=&quot;from wikipedia&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This bypass region is where the (cold) air stream is redirected from to create the reverse thrust.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.057" LastActivityDate="2014-05-08T15:23:14.703" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3779" PostTypeId="2" ParentId="3777" CreationDate="2014-05-08T15:23:56.860" Score="8" Body="&lt;p&gt;Not all air that flows through a &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbofan&quot;&gt;turbofan engine&lt;/a&gt; undergoes combustion. In a turbofan, part of the air (in some engines, &lt;em&gt;most&lt;/em&gt; of the air) is &lt;em&gt;bypassed&lt;/em&gt; around the power turbine; that air is simply accelerated by the compressor fan and is vented, cold, out the back of the engine to provide thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;cold-stream&lt;/em&gt; thrust reverser simply deflects this cold, bypassed air forward, whereas a &quot;normal&quot; thrust reverser deflects the main engine exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_reversal#Cold_stream_type&quot;&gt;Wikipedia has some pictures&lt;/a&gt; and more description.&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2014-05-08T15:23:56.860" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3780" PostTypeId="2" ParentId="275" CreationDate="2014-05-08T17:31:47.283" Score="3" Body="&lt;p&gt;Flutter is essentially an aerodynamic and structural interaction that has gone unstable. At certain speeds and flight conditions, the aero forces interact with the structural dynamics of the aircraft. This aero and structural dynamic instability can be seen in other places other than aircraft as well, the most famous that comes to mind is the one with the bridge rocking back and forth before collapsing&lt;/p&gt;&#xA;" OwnerUserId="2307" LastEditorUserId="774" LastEditDate="2014-05-08T19:24:54.457" LastActivityDate="2014-05-08T19:24:54.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3781" PostTypeId="1" CreationDate="2014-05-08T20:35:46.317" Score="16" ViewCount="1909" Body="&lt;p&gt;In most (all?) countries today, the official language for ATC communications is English.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before the Soviet Union collapsed, what was the official language for ATC communications in Russia and other Warsaw Pact countries? Was it Russian?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="718" LastEditDate="2014-05-08T22:15:41.067" LastActivityDate="2014-11-03T23:00:26.987" Title="Before the Soviet Union collapsed, what was Russia's official ATC language?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3782" PostTypeId="1" CreationDate="2014-05-08T21:17:58.160" Score="12" ViewCount="2775" Body="&lt;p&gt;In 2003, British Airways retired the Concorde for a few reasons.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Rising maintenance costs&lt;/li&gt;&#xA;&lt;li&gt;Lack of demand due to safety concerns&lt;/li&gt;&#xA;&lt;li&gt;Further decrease in demand due to 9/11 attacks&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;additionally, due to lack of competition, the Concorde was never properly maintained. Because no other airline had such a plane, British Airways kept the analog cockpit from 1970 up until the planes retirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, we live in a world where safety in aviation is continuing to increase, and the technology we have to utilize the world around us constantly gets better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What engineering breakthroughs will allow commercial aviation to use the upper atmosphere and supersonic cruising speeds?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;--EDIT--&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't mind if you downvote my question, but it certainly annoys me if you downvote and you don't &lt;strong&gt;leave a comment telling my why&lt;/strong&gt;. I've tried to make this question as objective as possible, if you're going to take the time to downvote, take the time to explain yourself, and I would be happy to try and mitigate your concerns.&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="267" LastEditDate="2014-07-27T18:58:40.813" LastActivityDate="2017-09-27T08:22:29.073" Title="What are the barriers to feasibility of stratospheric cruising for commercial air travel? (i.e. Concorde?)" Tags="&lt;commercial-aviation&gt;&lt;concorde&gt;" AnswerCount="6" CommentCount="16" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3783" PostTypeId="2" ParentId="3782" CreationDate="2014-05-08T21:47:13.027" Score="1" Body="&lt;p&gt;It's all about cost. Concorde stopped flying because it wasn't making money. The crash actually didn't mean that much economically, it's that it happened in the time of an economic downturn and executives couldn't be seen to get on a Concorde when they'd just laid off thousands of people. The airlines and airbus had had enough keeping it alive, so they are now all in museums. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tickets were fantastically expensive. Concorde was basically a scaled up fighter jet with fighter jet engines. It used afterburner for some segments of the flight, which requires vast amounts of fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason SST failed is the sonic boom made it practically impossible to fly any land routes. They tried a few times but it was just unworkable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will it ever come back? I'm sure it will one day once they solve certain problems. You have the fuel consumption issue for one. There are engines that do &quot;supercruise&quot;, giving high power without afterburners but they aren't exactly efficient. Either lowering fuel consumption or fuel costs is necessary. Second, you have the sonic boom. There are some promising designs out there which use specially shaped wings and fuselages to change and reduce sonic boom noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I think that rather than supersonic travel things will jump to hypersonic, super-high altitude travel. Once you are in the really thin air you don't have to worry about sonic booms, and you have much less air resistance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No matter how you cut it it's about cost though. If they can figure out a way to have supersonic travel with a cost enough people are willing to pay then they may build it, if not you'll never have it.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2017-09-27T07:25:38.980" LastActivityDate="2017-09-27T07:25:38.980" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3784" PostTypeId="2" ParentId="3782" CreationDate="2014-05-09T03:20:46.287" Score="9" Body="&lt;p&gt;I would argue that the Concorde was from the beginning economically unfeasible and instead served as a prestige technology for the British and French governments. Even the name Concorde, indicates that the two governments working together to produce the aircraft seemed the most important aspect of it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both British and France at the time had completely nationalized airlines and almost all their major aviation companies as well. Americans were going to the moon so Britain and France were looking around for a prestige technology of their own. Bigger and faster airplanes had been the rage for twenty years so the Concorde seemed like a cool thing to do. The Soviets came to the same conclusion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, civilian airline development was still wholly private so when when Boeing , Douglas et crunched the numbers they saw little value in supersonic transport with  it's non-linear cost. US supersonic transport never made it off the ground, but in Europe, the politically driven Concorde did because the people making the decisions weren't paying the bills.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted by others, the Concorde was essentially a military aircraft, produced by political compromise with the primary goal of expressing the technical powers of the governments involved. It was more an art project like building the Pyramids than it was a piece of mobile transportation infrastructure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: (May 14, 2014)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some sources on the economics of the Concorde:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theatlantic.com/past/docs/issues/77jan/gillman.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Atlantic August 1977:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Already Britain, and France spent £1.46 billion \$2.3 billion to reach this  (and a London political economist has recently argued that&#xA;  the true cost is roughly  three times this amount)...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...In May 1976, Professor David Henderson, newly appointed professor of political  economy at University College, London, argued&#xA;  that the government's figure of  £1.46 billion shared between Britain&#xA;  and France was a drastic underestimate.  It had been reached by adding&#xA;  the yearly expenditure on the project at the current prices.  If these&#xA;  were adjusted to 1975 prices, and interest charges of 10 percent&#xA;  added, then  the cost of Concorde was not £1.46 bilion but £4.26&#xA;  billion (\$6.82 billion at the  present exchange rate of \$1.60).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That would be &lt;a href=&quot;http://data.bls.gov/cgi-bin/cpicalc.pl?cost1=6.9&amp;amp;year1=1979&amp;amp;year2=2014&quot; rel=&quot;nofollow noreferrer&quot;&gt;$22 billion US (2014 dollars.)&lt;/a&gt; Just to get the thing into the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They built 26 of the aircraft, 20 of which that actually flew paid flights. So, around 1.1 billion per plane, roughly the cost of a B2 stealth bomber. I can't find any hard numbers on operating cost but with 1.1 billion per plane sunk capitial cost, it's clear it would never operate at a total profit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the plane only flew for 20+ years because &lt;a href=&quot;http://www.britishairways.com/concorde/faq.html#2&quot; rel=&quot;nofollow noreferrer&quot;&gt;the British government essentially gave it away&lt;/a&gt;, eating the billions of in development and deployment cost and leaving the plane to just have to cover operating cost. I'm not clear that it even really did that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering how much money was thrown at the problem, not particularly elegant or interesting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 02:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In rereading the parent, I realized I didn't make my answer explicit to the original question. He wanted to know what it would take to bring a Concorde like plane back. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;My answer was really just saying, &quot;the Concorde itself had no economic foundation so firstly, you'd have to find an economic niche for SST.&quot;&lt;/li&gt;&#xA;&lt;li&gt;There was never an economic demand for the Concorde's speed of travel and there doesn't seem to be one now, either. &lt;/li&gt;&#xA;&lt;li&gt;Technologically, you'd probably need something hyper radical like a nuclear powered air spike so the plane wouldn't burn tons of fuel and could fly over land masses without sonic booms or destroying smaller aircraft. (Seriously, it would have to be that advanced.)&lt;/li&gt;&#xA;&lt;li&gt;In our current luddite era, it would be saner to think about inventing anti-gravity drives than think that the political regulators would let that type of radical technology fly, even if it existed. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2300" LastEditorUserId="1467" LastEditDate="2017-09-27T08:22:29.073" LastActivityDate="2017-09-27T08:22:29.073" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="3785" PostTypeId="1" AcceptedAnswerId="11963" CreationDate="2014-05-09T03:33:22.550" Score="15" ViewCount="1698" Body="&lt;p&gt;This is a aviation principles question coming from my nine year old daughter that I need help with. I was explaining to her the principle of flight and the fact that you need airflow under the wing in order to create lift and that this is why an airplane in a steep climb will stall etc. So she said, why not have two large fans that blow air across the wings (we are not talking about the propellers here, but rather an external fan to create air-flow) so there is always un-interrupted airflow!!!! I am not sure exactly how to answer this. The best explanation I could think to give her was just as a sail boat cannot sail simply by placing a big fan on the boat.....but I don't think she was convinced.&lt;/p&gt;&#xA;" OwnerUserId="173" LastEditorUserId="572" LastEditDate="2015-02-19T09:39:22.190" LastActivityDate="2020-02-22T21:52:39.913" Title="How would you explain Bernoulli to a nine year old?" Tags="&lt;aerodynamics&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3786" PostTypeId="2" ParentId="3785" CreationDate="2014-05-09T05:56:22.393" Score="6" Body="&lt;p&gt;Drive on the freeway. Tell her to stick her arm out the window and pretend it's an airplane wing. That will be a great jumping off point for explaining how when the air flows over her arm, it creates areas of high and low pressure, which causes lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To explain high and low pressure to her, (which is a whole other can of worms entirely) bleed air from a bike tire. Also opening a soda can would help.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also it sounds like you need to explain Newton's Laws (or at least the third one). There are countless examples of this in every day life. You walk on the ground, the ground supports you, etc, etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everyone learns differently. Personally I'm an advocate of learning by experimentation, trial, and error. Try to find new ways to let her figure out the physics concepts on her own through experimentation, and then provide the academic understanding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind, lift, flow, and fluid mechanics are very broad concepts which require simplification for many years into the learning process. Which is what learning is, a process. Start small, build gradually, and you will see results faster than you think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Experience: I've been a student for most of my life, so I know a lot about not knowing much.&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="267" LastEditDate="2014-05-09T06:07:51.737" LastActivityDate="2014-05-09T06:07:51.737" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="3787" PostTypeId="2" ParentId="3785" CreationDate="2014-05-09T07:41:25.017" Score="8" Body="&lt;p&gt;Blow over the top of a piece of paper and it will rise up. It rises up for the same reasons as a wing does. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-05-09T07:41:25.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3788" PostTypeId="2" ParentId="3782" CreationDate="2014-05-09T07:48:50.787" Score="-1" Body="&lt;p&gt;Could it happen? Yes. Anything could happen.&lt;br/&gt;&#xA;Is there a realistic chance of it happening at some point in the future? Yes, quite likely, if there's an incentive to develop the technology that would make it economical.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Is that moment likely to arrive during my lifetime? I seriously doubt it, especially given the lead times for such projects which are measured in decades, and I don't have centuries to live (which suggest of course that I don't envision the technology that makes such an aircraft economically feasible to become available within the next few decades).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;There's no theoretical reason to assume that supersonic air transport can never be achieved. We know it's possible, it has been done. In fact it has been done several times.&lt;br/&gt;&#xA;Concorde, Konkordski, there was even (or so I've read) plans to create a transport version of the B-58 Hustler at some point, think a supersonic VIP and priority cargo transport for the US Air Force. There was an attempt to create a supersonic business jet by Sukhoi that was abandoned (I think) a few years ago.&lt;br/&gt; So we know it's possible, it's just not economical.&lt;br/&gt;&#xA;But who knows what may become economical in the future? If there's a large enough group of people who value their time more than the price of admission, there's a market. Right now that market isn't there, but it might emerge (the death of Concorde may have led to an increase in sales in long range business jet, if aviation laws get stricter, making it harder to use those, those owners might once again get interested in buying tickets on supersonic airliners and start asking airlines and governments, and aircraft manufacturers, to look into building them).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Or maybe there will be some revolution in aircraft design that makes it so cheap to build supersonic airliners that it just makes no sense to build anything else.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Of course that's all theoretical. There's no crystal ball anyone can look into and say definitely whether it will happen or not. But it might.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-05-09T07:48:50.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3789" PostTypeId="1" AcceptedAnswerId="3801" CreationDate="2014-05-09T08:35:55.280" Score="6" ViewCount="1260" Body="&lt;p&gt;In an earlier question &lt;a href=&quot;https://aviation.stackexchange.com/q/3782/1289&quot;&gt;What are the barriers to feasibility of stratospheric cruising for commercial air travel? (i.e. Concorde?)&lt;/a&gt; it was suggested that Concorde was not properly maintained as its analogue flight deck had never been upgraded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde production ceased in 1979. Fourteen Concordes saw commercial service. By end of operation in 2003 there were nine Concordes in use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Excluding the military, has any airline or manufacturer ever retrofitted a new design of flight deck to an existing fleet of old commercial airliners? &lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-07-20T12:18:33.510" Title="Has a commercial passenger airliner ever had its cockpit fully upgraded?" Tags="&lt;airliner&gt;&lt;aircraft-maintenance&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3790" PostTypeId="2" ParentId="3781" CreationDate="2014-05-09T09:09:58.760" Score="6" Body="&lt;p&gt;There are &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/1324620/&quot;&gt;suggestions&lt;/a&gt; that Soviet ATC was in Russian.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;User Codeshare  From Poland,&lt;/em&gt;&lt;br&gt;&#xA;  &lt;em&gt;posted Thu Jan 1 2004&lt;/em&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Back in the old days, as the old LOT pilots say, &lt;strong&gt;ATC transmissions were carried out only in Russian.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Plus there usually was some sort of agent when flying over the &lt;strong&gt;Soviet Union&lt;/strong&gt;.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Also some of these 'agents' were surprised when the pilots had exact maps of the airspace from Jeppesen or other maps. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-05-09T09:09:58.760" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3791" PostTypeId="2" ParentId="3789" CreationDate="2014-05-09T09:13:34.380" Score="3" Body="&lt;p&gt;There's a couple of cases I know of to hand. UPS upgraded their 727 fleet with glass cockpits, there's also an STC for a full DC9 cockpit upgrade. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-05-09T09:26:00.820" LastActivityDate="2014-05-09T09:26:00.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3792" PostTypeId="1" AcceptedAnswerId="3799" CreationDate="2014-05-09T09:27:50.930" Score="8" ViewCount="1334" Body="&lt;p&gt;I asked this in a side note to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3709/why-tap-the-brakes-on-take-off-in-fixed-gear-aircraft&quot;&gt;a previous question&lt;/a&gt;, but I figured it warranted its own question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a fixed gear aircraft is fitted with wheel fairings, even if you tapped the brakes after lift-off, would the wheels start turning again? With typical wheel-fairings I guess about one third to one quarter of the tire sticks out into the oncoming air flow, and would face perhaps 120 kts wind. All aircraft tires I've seen have grooves running along the direction of travel, with nothing going sideways that would be any obvious wind catcher, so I guess they're pretty much slicks in this regard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or would any 'normal' amount of friction in the bearings keep them from turning?&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="5517" LastEditDate="2019-12-02T16:08:16.500" LastActivityDate="2019-12-02T16:08:16.500" Title="Will landing gear with wheel fairings keep spinning due to airflow?" Tags="&lt;aerodynamics&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3793" PostTypeId="2" ParentId="3782" CreationDate="2014-05-09T10:29:40.923" Score="5" Body="&lt;p&gt;Concorde was a viable SST aircraft and was initially looking like it would sell quite well. Then US airports started banning it due to concerns over the sonic boom, which were really just sour grapes because US companies had failed to develop their own SST aircraft. That killed most of the orders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth noting that Russia flaw it's supersonic passenger jet for years quite successfully too. It had technical issues but, like with Concorde, the sonic boom issue turned out to be of little real concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of research has gone into lessening sonic booms, but it isn't clear if this will actually help. Given the attitude of the US commercial flight industry it seems likely that unless Boeing's name is on the aircraft they would resist it anyway. I think it is more likely that such an aircraft would be developed and used mostly in the far east. China might do it, or Japan.&lt;/p&gt;&#xA;" OwnerUserId="2311" LastActivityDate="2014-05-09T10:29:40.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3794" PostTypeId="1" AcceptedAnswerId="3798" CreationDate="2014-05-09T12:14:53.357" Score="33" ViewCount="22518" Body="&lt;p&gt;Is there a special protocol for a situation where the on-board radio communication equipment suddenly breaks down? Would the pilot be able to land on a busy towered airfield or would they be forced to look for a small landing strip in the middle of nowhere?&lt;/p&gt;&#xA;" OwnerUserId="2172" LastEditorUserId="1696" LastEditDate="2015-10-19T19:12:39.170" LastActivityDate="2019-06-18T16:51:00.380" Title="How would an airplane land if the on-board radio breaks down?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;radio-communications&gt;&lt;lost-communications&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3795" PostTypeId="2" ParentId="3794" CreationDate="2014-05-09T12:27:41.537" Score="18" Body="&lt;p&gt;First thing you do when the radio breaks down is to start squawking 7600 (the code for radio malfunction) on your transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then when you approach the airport they will attempt to contact you first through radio (to see if you can still hear them) and you use alternate means of replying (sending IDENT on transponder, rocking your wings,...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can't hear them they will use a light gun to convey messages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/D4Z6A.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="1289" LastEditDate="2014-05-09T12:39:54.410" LastActivityDate="2014-05-09T12:39:54.410" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3796" PostTypeId="2" ParentId="3792" CreationDate="2014-05-09T13:26:08.920" Score="4" Body="&lt;p&gt;My plane has fixed gear with wheel pants.  When the wheels are spinning right after take off I can feel the vibration (it's a really small plane).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I tap the brakes or wait a minute or so, the vibration stops and doesn't start again.  My guess is that there's too much friction in the wheel/axle to permit the wheels to spin.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you've noted, there's not much on the tire to catch the wind anyway.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-05-09T13:26:08.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3797" PostTypeId="2" ParentId="3794" CreationDate="2014-05-09T13:29:29.393" Score="15" Body="&lt;p&gt;Ratchet Freak has a good answer.  In addition, please &lt;a href=&quot;https://aviation.stackexchange.com/questions/1998/if-the-radio-fails-can-a-pilot-contact-the-tower-by-cell-phone&quot;&gt;pull out your cellphone and try calling the tower&lt;/a&gt;.  Somewhere in the bottom of my flight bag I have a small book with telephone numbers at towers.  If you don't have that, call Lock-Mart Flight Service at 1-800-wx-brief tell him you need the tower number.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also remember that there is no requirement for a radio in an airplane.  NORDO (No Radio) aircraft are perfectly legal although in practice, they operate mostly out of non-towered fields.  Operating out of a towered airport is still possible, but it requires prior coordination with the tower.  Note please that flight in the SFRA around Washington DC does require a radio, and I have seen no procedures to allow for NORDO aircraft in this area.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your radio stops working, one option is to fly to a non-towered field and do what the NORDO planes do: Overfly the field at a safe altitude, note wind direction from the wind sock or tetrahedron, note other traffic in the area, and fit yourself into the traffic pattern... and land.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-05-29T15:08:14.907" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3798" PostTypeId="2" ParentId="3794" CreationDate="2014-05-09T13:30:19.520" Score="39" Body="&lt;p&gt;It is important to remember that it is often difficult to diagnose radio malfunction during flight. Therefore it is hard to know whether you have a malfunctioning transmitter, a malfunctioning receiver, or perhaps both. You also have the point-of-failure that is the headset you are using. For this reason it is quite usual to carry a spare headset and the first piece of diagnostics is to swap headsets. Many General aviation aircraft also have a handheld microphone and speakers integrated into the radio stack.&lt;/p&gt;&#xA;&lt;p&gt;Once you've ascertained that its the actual transmitter and/or receiver that has failed it is common to set the transponder to 7600. For landing, the relevant detail for the procedure to follow is contained within &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;Chapter 4, Section 2-13 of the AIM&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;h3&gt;Receiver Inoperative&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Remain outside class D airspace until the direction of air traffic can be ascertained&lt;/li&gt;&#xA;&lt;li&gt;Notify the tower your type, position, altitude, intention to land and request you are controlled with light signals&lt;/li&gt;&#xA;&lt;li&gt;At 3 -5 miles, advise the tower of your position and join the traffic pattern&lt;/li&gt;&#xA;&lt;li&gt;Watch the tower for light signals&lt;/li&gt;&#xA;&lt;li&gt;Continue to advise of position (downwind, turning base, etc)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Transmitter inoperative&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Remain outside class D airspace until the direction of air traffic can be ascertained&lt;/li&gt;&#xA;&lt;li&gt;Monitor the primary local control frequency as depicted on sectional charts for landing or traffic info.&lt;/li&gt;&#xA;&lt;li&gt;Look out for light signals that may be directed to your aircraft&lt;/li&gt;&#xA;&lt;li&gt;During hours of daylight, acknowledge tower transmissions or light signals by rocking your wings&lt;/li&gt;&#xA;&lt;li&gt;At night, acknowledge by blinking landing of navigation lights&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Transmitter &amp;amp; Receiver inoperative&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Remain outside class D airspace until the direction of air traffic can be ascertained&lt;/li&gt;&#xA;&lt;li&gt;Maintain visual contact with the tower and acknowledge light signals as above.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The light signals used for an aircraft in flight are as follows&lt;sup&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0302.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Steady green&lt;/strong&gt; - Cleared to land&lt;br /&gt;&#xA;&lt;strong&gt;Flashing green&lt;/strong&gt; - Cleared to approach airport, or return to land&lt;br /&gt;&#xA;&lt;strong&gt;Steady red&lt;/strong&gt; - Continue circling, give way to other aircraft&lt;br /&gt;&#xA;&lt;strong&gt;Flashing red&lt;/strong&gt; - Airport unsafe, do not land&lt;br /&gt;&#xA;&lt;strong&gt;Alternating red and green&lt;/strong&gt; - Exercise extreme caution&lt;/p&gt;&#xA;&lt;p&gt;They can be seen in &lt;a href=&quot;https://www.youtube.com/watch?v=U7sVkPnCB3Y&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-10-01T20:36:20.040" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3799" PostTypeId="2" ParentId="3792" CreationDate="2014-05-09T13:35:00.040" Score="4" Body="&lt;p&gt;When flying in formation, I've witnessed landing gear with and without fairings continue to spin for the duration of the flight. I think it really all depends on the specific aircraft designs.&lt;/p&gt;&#xA;" OwnerUserId="423" LastActivityDate="2014-05-09T13:35:00.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3801" PostTypeId="2" ParentId="3789" CreationDate="2014-05-09T14:38:13.153" Score="6" Body="&lt;p&gt;While many times an upgrade is not economical for older airplanes, sometimes the new features make it worth the cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two examples I found were &lt;a href=&quot;http://www.flightglobal.com/news/articles/picture-southwest-launches-737-300-cockpit-upgrade-with-boeing-and-320450/&quot;&gt;Southwest upgrading their 737-300 fleet&lt;/a&gt;, and &lt;a href=&quot;http://aviationweek.com/awin/new-flight-deck-could-ease-nextgen-older-aircraft&quot;&gt;Delta upgrading their MD-88 and MD-90 fleet&lt;/a&gt;. The second article also mentions American and Icelandair 757 and 767 upgrades. The Southwest and Delta upgrades involve over 100 aircraft in each case, which probably helped to make the upgrades more economical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both cases, a major factor mentioned was the ability to perform required navigation performance (&lt;a href=&quot;http://en.wikipedia.org/wiki/Required_Navigation_Performance&quot;&gt;RNP&lt;/a&gt;) procedures with GPS and other modern features. As the FAA works to implement the &lt;a href=&quot;http://en.wikipedia.org/wiki/Next_Generation_Air_Transportation_System&quot;&gt;NextGen&lt;/a&gt; ATC system in the US, these upgrades will offer more benefits for the operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I'd like to comment on the following statement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Concorde was not properly maintained as its analogue flight deck had never been upgraded.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Proper maintenance and technology upgrades are not always the same thing. Aircraft with older systems can be maintained just as well as newer planes. We have airplanes that are 50 years old or older, like the DC-3, which are still flying. While technology upgrades certainly have benefits, aircraft with analog cockpits are still operating just fine around the world. They may not be the most modern machines out there, but proper maintenance is what has kept them flying this long.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-09T14:38:13.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3802" PostTypeId="1" AcceptedAnswerId="3803" CreationDate="2014-05-09T14:48:37.647" Score="10" ViewCount="862" Body="&lt;p&gt;It has been asked and answered here that the ASEL is for Land operations and ASES for Seaborne. Are there requirements specific to using snow-ski equipped planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am most interested in the US, although discussions of other places is fine.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2" LastEditDate="2014-05-09T16:23:07.520" LastActivityDate="2014-05-09T16:23:07.520" Title="Are any special certs or licenses needed for Snow-ski equipped planes?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3803" PostTypeId="2" ParentId="3802" CreationDate="2014-05-09T14:53:32.270" Score="10" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook/media/faa-h-8083-23-4.pdf&quot;&gt;From the FAA manual:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Title 14 of the Code of Federal Regulations (14 CFR)&#xA;  part 61 does not require specific pilot training and&#xA;  authorization to operate skiplanes; however, it is&#xA;  important to train with a qualified skiplane flight&#xA;  instructor.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Since most skiplanes operate in a wide variety of conditions,&#xA;  such as landing on frozen or snow-covered&#xA;  lakes and sloping glaciers, with varying qualities of&#xA;  snow, it is important to know how performance is&#xA;  affected. Use the performance data provided by the&#xA;  manufacturer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From looking at 14 CFR part 61, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#14:2.0.1.1.2.1.1.5&quot;&gt;section 61.5&lt;/a&gt; lists the different ratings. While it differentiates sea and land, there is no &quot;ski&quot; category.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-05-09T15:06:24.230" LastActivityDate="2014-05-09T15:06:24.230" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3804" PostTypeId="1" AcceptedAnswerId="3809" CreationDate="2014-05-09T15:04:35.460" Score="8" ViewCount="4969" Body="&lt;p&gt;A couple of months ago I was watching some &lt;a href=&quot;http://en.wikipedia.org/wiki/Ice_Pilots_NWT&quot;&gt;Ice Pilots NWT&lt;/a&gt; re-runs, and I noticed they kept saying 'overshoot' when talking about a go-around. Is this standard Canadian phraseology? Or is it perhaps old phraseology? Or is it simply reworded for the benefit of the TV audience?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not asking about the meaning of the word 'overshoot' which is quite clear, but it was being used were every pilot I know would use the word 'go-around', i.e. calling &quot;overshoot, overshoot, overshoot&quot; when shoving the throttles forward.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="572" LastEditDate="2015-02-19T09:38:58.187" LastActivityDate="2015-07-21T18:27:53.320" Title="Why do some pilots call a go-around an 'overshoot'?" Tags="&lt;phraseology&gt;&lt;go-around&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3805" PostTypeId="2" ParentId="3785" CreationDate="2014-05-09T16:33:16.067" Score="15" Body="&lt;p&gt;Bernoulli's principle is probably not the best starting point to explain lift generation, especially if you do not first explain the origin of the Bernoulli effect! Naïve invocations of Bernoulli have led to a number of incorrect 'explanations' that are quite widely circulated, such as the idea that air flows faster over the upper surface of a wing because it is more curved that the lower, and thus creates a longer path. If this explanation were correct, paper airplanes and inverted flight would be impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bernoulli's principle is a consequence of Newton's laws of motion applied to incompressible fluid flow. To explain lift, you can start by invoking Newton directly, by observing that lift is the reaction to the wing's downwards acceleration of the airflow around it. Bernoulli enters the picture when you get to calculating the changes in pressure and velocity within that airflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this perspective, we can see that while blowing air over a wing would create some lift, as the wing will deflect at least some of that airflow downwards, you would get more lift by pointing the fan directly downwards. This is, of course, what a helicopter does, and it takes a lot of power, so wing-blowing, being a less-effective way of generating lift, would require even more. If, instead, you use the fan as a propeller, you only have to produce enough thrust to counter the drag, which may be as little as 1/50 of the lift.&lt;/p&gt;&#xA;" OwnerUserId="1981" LastActivityDate="2014-05-09T16:33:16.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3806" PostTypeId="2" ParentId="3794" CreationDate="2014-05-09T16:44:11.270" Score="7" Body="&lt;p&gt;I was a Junior Technician, later Corporal, Air Wireless Fitter in the R.A.F. in 1952-4, servicing Gloster Meteors' radios at a Flying Training School, and the signal then was for the pilot to waggle the aircraft's wings as he approached, or flew by, on his way to land, to show he could not contact the Control Tower. Then we had to fix it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was made a Corporal so that I could sign off our work on the aircraft out on the airfield, usually just tuning up to a new crystal to suit the frequencies of a distant Station. I got the promotion so the Sergeant could stay in the nice warm office: I didn't mind -- I was &quot;/Paid&quot; extra, nice for a &quot;National Service Only&quot; erk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Happy days&lt;/p&gt;&#xA;" OwnerUserId="2312" LastActivityDate="2014-05-09T16:44:11.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3807" PostTypeId="1" AcceptedAnswerId="3808" CreationDate="2014-05-09T17:50:45.460" Score="9" ViewCount="886" Body="&lt;p&gt;It's supposed to be that electronic gadgets' emission are dangerous for airplane systems. If this is true, why don't they use any detectors to locate such emissions?&lt;/p&gt;&#xA;" OwnerUserId="2313" LastEditorUserId="511" LastEditDate="2014-05-09T17:55:50.707" LastActivityDate="2014-05-16T03:20:15.997" Title="If turning off electronic gadgets is so important, why are there no detectors used to find them?" Tags="&lt;safety&gt;&lt;electronics&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3808" PostTypeId="2" ParentId="3807" CreationDate="2014-05-09T18:09:56.047" Score="10" Body="&lt;p&gt;Three reasons I can think of:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It's easy to detect the general presence of a specific transmitting device (a WiFi antenna, say), but very hard to &lt;em&gt;precisely localize&lt;/em&gt; it. They could tell if there's one on the plane, but someone with a very sensitive piece of equipment would have to walk up and down the aisles pointing it at people to actually find it in somebody's pocket. And cellphones (when not in use) are generally burst transmitters: they don't broadcast continuously, they just &quot;ping&quot; the tower every so often. This means it could take a long time and a lot of aisle-pacing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Many &quot;electronic devices&quot; which are banned are entirely passive and have no traceable[*] emissions. Think cameras, handheld GPS receivers, iPods. (On the other hand this passiveness also means they are extremely unlikely to harmfully interfere with the operation of the airplane, but right or wrong, such devices are still banned in some cases.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's &lt;em&gt;not that important&lt;/em&gt;. There are a few incidents where electronic interference is suspected as a possible factor, but no conclusive evidence. As soon as there is actually a fatal accident where an electronic device can be conclusively blamed as the cause (and I doubt this will happen), the airlines will be a &lt;em&gt;lot&lt;/em&gt; more willing to spend the kind of money that would be required to implement this.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For a full, evidence-based discussion of the actual risks, I refer you to this question on Skeptics Stack Exchange: &lt;a href=&quot;https://skeptics.stackexchange.com/questions/1118/are-personal-electronics-a-risk-to-commercial-aviation&quot;&gt;Are personal electronics a risk to commercial aviation?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[*] No &lt;em&gt;traceable&lt;/em&gt; emissions. All electronic devices generate some very, very tiny incidental signals. But these are so weak that they will be virtually impossible to detect on a crowded plane filled with its own (approved) electronics. Such emissions are measured in laboratories with extremely sensitive antennas in special, heavily-shielded rooms under carefully controlled conditions.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:46:45.343" LastActivityDate="2014-05-09T18:44:21.460" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3809" PostTypeId="2" ParentId="3804" CreationDate="2014-05-09T18:19:54.260" Score="17" Body="&lt;p&gt;Looking at the &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/opssvs/secretariat-terminology-glossary-744.htm&quot;&gt;Glossary for Pilots and Air Traffic Services Personnel (TP 11958E)&lt;/a&gt; at the Government of Canada web site, the definitions of overshoot and go-around are &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;overshoot&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) To pass beyond the limit of the runway or landing field when&#xA;  trying to land.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fr: dépasser&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Other expression for: go-around&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“Go around”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An expression used in radiocommunications to instruct a pilot to&#xA;  abandon an approach or landing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fr: « Remettez les gaz »&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;go-around&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The procedure followed by a pilot who decides to abandon an approach&#xA;  or landing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fr: remise des gaz&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Plus, looking at various Flight Test Guides listed at the &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/publications/menu.htm#training&quot;&gt;Canadian Government Air Transportation site&lt;/a&gt; it appears that pilots in Canadian flight schools are taught &quot;overshoot&quot; procedures for missed approaches (vice go-around).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeing as you were watching a reality TV show dealing with Canadian pilots, it is not surprising they use the terminology they were most likely taught in flight school (in Canada).&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2014-05-09T21:53:06.293" LastActivityDate="2014-05-09T21:53:06.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3810" PostTypeId="2" ParentId="3792" CreationDate="2014-05-09T18:46:38.677" Score="5" Body="&lt;p&gt;This is a very general question. So the answer is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes they spin, sometimes they don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you ever seen a car with a bicycle on a trunk rack, and the front wheel is spinning. Sometimes they spin fast, sometimes slow, sometimes not at all. It just depends on the air flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane wheels are the same way, and it all depends on the airflow, the tires and the bearings. The airflow over tires sticking out from wheel pants is going to be turbulent and unpredictable. Sometimes it happens, sometimes it doesn't. I've seen both.&lt;/p&gt;&#xA;" OwnerUserId="1900" LastActivityDate="2014-05-09T18:46:38.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3812" PostTypeId="2" ParentId="3690" CreationDate="2014-05-09T20:29:14.107" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/NASA_X-43&quot; rel=&quot;nofollow&quot;&gt;NASA X-43A&lt;/a&gt; got up to almost Mach 10, I think that's pretty close to a record for an air breathing atmospheric vehicle.  &lt;/p&gt;&#xA;" OwnerUserId="534" LastActivityDate="2014-05-09T20:29:14.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3814" PostTypeId="1" AcceptedAnswerId="3816" CreationDate="2014-05-10T01:27:39.917" Score="16" ViewCount="3825" Body="&lt;p&gt;I'm a bit of a photographer and I keep thinking it would be fun to try and do some shots aloft.  Only trick is, I'm not sure what kind of plane I would want to use to get those pictures done.  I'd have to rent the plane and the pilot and I'd like to keep the price down as best as possible...  So a purpose built plane isn't such a big deal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other considerations&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Good view of the ground, though it doesn't have to be straight down (I'm not doing surveying&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stable while banking so I can more easily track shots when the plane is at an angle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ability to be held stably at a bank without actually turning the craft, again to help me track my shots.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Low vibration, for the same reason as stated over the last two.&lt;/li&gt;&#xA;&lt;li&gt;Big windows&lt;/li&gt;&#xA;&lt;li&gt;Can fly low and slow for if I want to get close to things (within reason.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, a high wing is probably preferred.  Though, if it's exceptionally good at holding a bank, it may not matter.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think of anything else that I should consider to keep my camera from being jangled about, and to allow me to have a good view so I can get some shots...  Please feel free to leave them in the comments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what plane would work best for this mission?  &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2018-04-12T20:58:00.900" LastActivityDate="2018-04-13T17:23:10.077" Title="What is a good plane for aerial photography?" Tags="&lt;general-aviation&gt;&lt;aircraft-operations&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3815" PostTypeId="1" AcceptedAnswerId="3850" CreationDate="2014-05-10T02:10:18.233" Score="18" ViewCount="10455" Body="&lt;p&gt;Using a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerostat&quot; rel=&quot;noreferrer&quot;&gt;Lighter Than Air (LTA) Hybrid Airship&lt;/a&gt; to &lt;a href=&quot;http://edition.cnn.com/2013/12/09/business/airship-cargo-revolutionize-arctic-transportation&quot; rel=&quot;noreferrer&quot;&gt;efficiently transport cargo to remote areas&lt;/a&gt; seems like an idea that should flourish.  It allows access to remote places in the world that have no airports, harbors, or roads leading to them by providing a point-to-point delivery system with vertical take-off and landing, all while providing a &lt;a href=&quot;http://www.scientificamerican.com/article/is-there-a-future-for-airships/&quot; rel=&quot;noreferrer&quot;&gt;greener solution&lt;/a&gt;.  I see at least three players all trying to enter this market which seems perpetually stuck as coming about in the next 4-5 years and all seem to have benefited from the U.S. Army's Long Endurance Multi-intelligence Vehicle (LEMV) project that was &lt;a href=&quot;http://www.gizmag.com/lemv-airship-canceled/26274/&quot; rel=&quot;noreferrer&quot;&gt;canceled in January 2013&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.hybridairvehicles.com&quot; rel=&quot;noreferrer&quot;&gt;Hybrid Air Vehicles&lt;/a&gt; in the U.K. has partnered with Northrop Grumman owns a prototype that came out of the LEMV project and plans to build a 50-ton capacity airship in about five years.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://aeroscraft.com&quot; rel=&quot;noreferrer&quot;&gt;Aeroscraft&lt;/a&gt; in the U.S. has a prototype and plans to build an airship that carries a 66-ton load as &lt;a href=&quot;http://www.history.com/shows/rise-of-the-machines/videos/rise-of-the-machines-super-airship&quot; rel=&quot;noreferrer&quot;&gt;shown on the History channel&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.lockheedmartin.com/us/products/HybridAirship.html&quot; rel=&quot;noreferrer&quot;&gt;Lockheed Martin&lt;/a&gt; has a P-791 / SkyTug prototype derived from the LEMV program and hopes to build a SkyFreighter to lift a 70-ton cargo.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It appears none of these companies has any current orders and are all &lt;a href=&quot;http://www.ocregister.com/articles/aeroscraft-611707-air-blimp.html&quot; rel=&quot;noreferrer&quot;&gt;looking for funding&lt;/a&gt; to build their proposed cargo airships.  Apparently an investment of on the order of 50 to 250 million USD would allow one of these to be built for commercial use.  While this is a lot of money, it is small compared to other aviation investments. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;noreferrer&quot;&gt;Boeing 787 Dreamliner&lt;/a&gt; required 32 billion USD as of 2011.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, all such airships use noble gas helium instead of the very flammable hydrogen used in the Hindenburg accident, so the historical fear of using such ships should not apply to the new technologies.  These proposed ships are planned to travel at between 70 and 115 MPH, so while not as fast as airplanes, they do compete with trucking and shipping speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, given the relatively small cost to develop one of these cargo lift systems, why hasn't a company like Boeing with deep pockets wanted to invest in such systems and these companies continue to search for funding?  Is there some kind of flaw in the proposal that such a new cargo shipping approach would save money?  Is it that the market is too small to interest big companies? The hangar space required to store and maintain these ships is huge and little such infrastructure currently exists, perhaps that is their downfall?  Alternatively, maybe their maintenance requirements are their Achilles heel?&lt;/p&gt;&#xA;" OwnerUserId="2317" LastEditorUserId="609" LastEditDate="2015-04-09T14:52:12.917" LastActivityDate="2020-07-30T11:21:56.773" Title="Why have cargo hybrid airships not succeeded in the market?" Tags="&lt;general-aviation&gt;&lt;cargo&gt;" AnswerCount="7" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3816" PostTypeId="2" ParentId="3814" CreationDate="2014-05-10T02:12:49.480" Score="11" Body="&lt;p&gt;Well, the first caveat is that the best plane for aerial photography is one that &lt;em&gt;someone else&lt;/em&gt; is flying -- Trying to set up shots while also maneuvering an aircraft is difficult at best, and can be dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hitting your specific points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Good view of the ground&lt;/strong&gt;&lt;br&gt;&#xA;This generally implies a high wing aircraft, assuming you're shooting from inside the plane. (If you're mounting external cameras this is much less of a consideration.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Stable while banking&lt;/strong&gt; &amp;amp; &lt;strong&gt;Able to fly banked without turning&lt;/strong&gt;&lt;br&gt;&#xA;Properly flown pretty much any aircraft can fly along indefinitely in an &lt;a href=&quot;http://en.wikipedia.org/wiki/Slip_%28aerodynamics%29&quot;&gt;aerodynamic slip&lt;/a&gt; -- it's not an aerodynamically favorable configuration, but meeting this requirement shouldn't be a problem.&lt;br&gt;&#xA;The need to maintain the aircraft in a slip is however one of the reasons you probably want to have someone else flying. While not &lt;em&gt;difficult&lt;/em&gt; it is not the way the plane &quot;wants&quot; to be flying.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Low Vibration&lt;/strong&gt;&lt;br&gt;&#xA;Give up the idea of long telephoto lenses or slow shutter speeds -- at least unless you have some kind of image stabilization in your lens/camera.  Most GA aircraft will have some appreciable vibration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Big Windows&lt;/strong&gt;&lt;br&gt;&#xA;&quot;Big&quot; may be less important than &quot;Removable&quot; -- Most light GA airplanes will have windows of a reasonable size (at least in the front seats), but aircraft plexiglass windows are not of the best optical quality, so you might not want to shoot through them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Able to flow low and slow&lt;/strong&gt;&lt;br&gt;&#xA;The optimal aircraft here is a helicopter (in fact some might argue that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Robinson_R22&quot;&gt;R22 helicopter&lt;/a&gt; is a great photo platform - but beware the vibration), but most GA training airplanes can do an adequate job here.&lt;br&gt;&#xA;Again, a plug for having someone else fly: Trying to photograph something on the ground while flying low and slow is a recipe for a &lt;a href=&quot;http://ronsrv7project.blogspot.com/2010/07/skids-slips-moose-stalls-hobbs-2285-hrs.html&quot;&gt;&quot;moose stall&quot;&lt;/a&gt;, which frequently doesn't end well for anyone except the moose.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;My recommendations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the typical GA airplane fleet I would pick a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_152&quot;&gt;Cessna 152&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot;&gt;Cessna 172&lt;/a&gt;. These planes are pretty much ubiquitous, and among their advantages are the large hinged windows which you can flip up and pop a camera out of.&lt;br&gt;&#xA;You might also consider &quot;jump planes&quot; which are certificated for flight with a door open or removed, providing you a giant hole in the fuselage through which you can take photos (as well as anchor points to attach yourself and your equipment to the airframe).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you will need to hold station over your target a R22 or similar helicopter would probably be your best choice (and the R22 can certainly be flown without doors).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Protecting your equipment&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At a bare minimum you should be wearing a substantial wrist strap. Anchoring yourself and your equipment to the airframe is also an excellent idea, as having expensive camera gear fall out of an aircraft can be quite unpleasant (both for you - as the gear will likely be destroyed - and for people on the ground who get clobbered by it).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-10T02:12:49.480" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3817" PostTypeId="2" ParentId="3814" CreationDate="2014-05-10T13:13:02.240" Score="16" Body="&lt;p&gt;I used to work at a sport parachuting center - we occasionally had photographers rent one of our Cessna 182 airplanes for the same purpose. An advantage of jump planes is the pilots are quite used to odd attitudes (and even odder requests) so a 60 degree bank angle with the door open and you leaning out of it will get a reply of &quot;no problem&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our conditions were the photographer wears a parachute, a seatbelt, and if the camera goes for a jump that's just too bad for your wallet. 30 minute lecture on what to do if you fall out. Short form: drop camera, grab this handle, pull. And the trip's over if you do anything silly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would sit on the floor where the co-pilot's seat would normally be, the pilot will open the door as needed, and you have a clear view out the right rear quarter of the plane. Obstacles are the wheel (front half of the door looking down) and wing strut (forward) - the tail is well out of the way. It's very noisy, but unless your camera is actually outside the fuselage the wind blast is not an issue. Don't change lenses though, and your clip-on lens hood will probably disappear rather quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can sit on the door ledge with your feet outside and have an excellent, stable field of view with both hands free to operate your camera. I've sat there hundreds of times without a seatbelt, it's no problem even in steep turns. Just a bit odd seeing the ground above the wingtip. Difference is, I don't care if I fall out.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-05-10T13:13:02.240" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3818" PostTypeId="2" ParentId="3807" CreationDate="2014-05-10T16:48:50.567" Score="0" Body="&lt;p&gt;&lt;strong&gt;Due to plentiful aircraft shielding and low power emissions of personal electronic devices, practically speaking only a malfunctioning electronic unit that is transmitting the exact same frequencies that the antennas are designed to receive and filter out carry significant probabilities of affecting avionics.&lt;/strong&gt; One hundred iphones with wi-fi turned on would almost always have an effect, as they would not be emmiting signals received by the antennas. (If there was a rare malfunction a signal could pass from the cabin, through the window and into a GPS receiver, for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To identify the position of a malfunctioning unit one would need expensive multiple receivers and a computer that triangulates the location.  This is just too expensive for the low risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you could identify a malfunctioning unit, the unit would notmyet be malfunctioning otherwise the aircarft would already be receiving the bad signal and in a sense the aircaft systems are the first detection.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;On the whole the answer lies in the fact that the interference for the odd electronic, people forget to turn off is low risk and does not justify the expense of an advanced locator system.&lt;/strong&gt;  It is the aircraft that provides the saftey by properly shielding its electronics from interfering signals to begin with.  The antennas restrict communication on narrow frequencies amd usually with certain communication protocols, so even at the right frequency disturbing the aircarft instrumentation or navigation is a freak accident. I think the most probable interference is that a malfunctioning noise transmission across various uncontrolled frequencies could distort the coding a proper signal trying to communicate through the antenna to a given receiver. &lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="2213" LastEditDate="2014-05-13T13:26:51.920" LastActivityDate="2014-05-13T13:26:51.920" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3819" PostTypeId="2" ParentId="3814" CreationDate="2014-05-10T19:30:55.043" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www.taosaerialimages.com/gallery/resources/index.html&quot; rel=&quot;noreferrer&quot;&gt;Chris Dahle-Bredine&lt;/a&gt; (author of Shot From Above) uses an ultralight for this kind of photography.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's cheap, only burns a little gas, is cheap to maintain, has lots of visibility, and he takes amazing shots!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rxiB2.png&quot; alt=&quot;Chris in his ultralight&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-05-10T19:30:55.043" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3820" PostTypeId="2" ParentId="3814" CreationDate="2014-05-10T22:36:31.463" Score="2" Body="&lt;p&gt;I'm going to try to offer an out-of-the-box solution and suggest a remote-controlled &lt;a href=&quot;http://en.wikipedia.org/wiki/Quadcopter&quot; rel=&quot;nofollow&quot;&gt;quadcopter&lt;/a&gt; / octocopter UAV with a camera mounted on it.  Such a system seems to satisfy most of your stated and implied needs:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'd have to rent the plane and the pilot and I'd like to keep the price down as best as possible.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A UAV seems like an excellent choice in this regard: unmanned vehicles tend to be cheaper than manned ones, and don't require a pilot's license to operate (although &lt;a href=&quot;http://en.wikipedia.org/wiki/Unmanned_aerial_vehicle#FAA_designation_and_legal_regulation&quot; rel=&quot;nofollow&quot;&gt;other regulations may still apply&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You probably &lt;em&gt;do&lt;/em&gt; still need a skilled operator, since controlling a quadcopter does take some practice, and it's difficult (not to mention potentially dangerous) to control the vehicle and the camera at the same time.  Having a separate pilot frees you from having to do that job yourself, and lets you concentrate fully on taking pictures.  The commercial operators I know of that do this kind of work always have a separate pilot and camera operator.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Good view of the ground, though it doesn't have to be straight down (I'm not doing surveying). [...] Big windows. [...] Also, a high wing is probably preferred. Though, if it's exceptionally good at holding a bank, it may not matter.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Check.  The setups I've seen usually have the camera mounted &lt;em&gt;under&lt;/em&gt; the vehicle body, so you can point it in any direction, including straight down, and the only things that could possibly get in the way are the landing struts.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Stable while banking so I can more easily track shots when the plane is at an angle.&lt;/li&gt;&#xA;  &lt;li&gt;Ability to be held stably at a bank without actually turning the craft, again to help me track my shots.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Check, sort of.  No, the quadcopter itself can't maintain a steady tilt without accelerating, but the rigs I've seen let the &lt;em&gt;camera&lt;/em&gt; be held steady at any angle, while the copter can freely move in any direction in three dimensions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Low vibration, for the same reason as stated over the last two.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Check.  At least, I've never heard of this being a problem.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Can fly low and slow for if I want to get close to things (within reason.)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the one aspect in which remote-controlled helicopters &lt;em&gt;absolutely excel&lt;/em&gt;: they can hover in place, or move at any desired speed (for panning shots), at any altitude above ground level.  Want to hover in front of someone's face to shoot a portrait of them?  Perfectly possible (if maybe a little bit unnerving).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mind you, I haven't actually flown or worked with such systems myself; most of my knowledge comes from watching a demonstration at a &quot;maker faire&quot;-style event by &lt;a href=&quot;http://helicam.aero/&quot; rel=&quot;nofollow&quot; title=&quot;Helicam aerial cinematography&quot;&gt;a local company&lt;/a&gt; operating such systems, and exchanging a few words with the folks there.  But it was definitely impressive, and the way &lt;em&gt;I&lt;/em&gt; would go if I ever needed to do some aerial photography.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there certainly are also some photography applications for which remote-controlled vehicles are not so well suited, such as high altitudes, very long flight times, flight over significant distances of inaccessible terrain or operation in bad weather.  However, if your requirements don't include any of those, they may well be much more practical and less costly than renting a manned aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1309" LastActivityDate="2014-05-10T22:36:31.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3821" PostTypeId="2" ParentId="3815" CreationDate="2014-05-11T01:58:25.640" Score="4" Body="&lt;p&gt;There are two primary difficulties with lighter-than-air cargo craft that none of the named companies address; and which give pause to companies such as Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First: the continued dependence upon very large hangars; both for construction of large airships, and for their protection and maintenance.   Any viable cargo fleet would comprise a fair number of craft, and an added investment into numerous huge buildings.  This is an obvious &quot;no win&quot; situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second: Virtually all airships continue to use flexible, lightweight fabrics or laminated materials for their hulls.   In order for the envelopes to be gastight, weatherproof, resistant to degradation in ultraviolet light, and still have the tensile strength needed, it becomes too expensive to create large fleets of airships.  Indeed, the materials used for modern airships are similar to those used for space suits; and there is an extremely limited number of suppliers or sources for these types of exotic and high tech materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Happily, there is a solution!&#xA;First, design airships that no longer need hangars.  Not for construction, and not for storage or protection.&#xA;Second, use commonly available materials such as aluminum and carbon fiber to build airship hulls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;who is doing this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Me.&lt;/p&gt;&#xA;" OwnerUserId="2321" LastActivityDate="2014-05-11T01:58:25.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3822" PostTypeId="1" CreationDate="2014-05-11T03:10:01.110" Score="9" ViewCount="544" Body="&lt;p&gt;In the 1950's and 1960's, there were vehicle (and passenger) &lt;strong&gt;air ferries&lt;/strong&gt; operated by planes such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Bristol_Freighter&quot;&gt;Bristol Freighter&lt;/a&gt;. Mostly across the English Channel (England to France), by companies like &lt;a href=&quot;http://en.wikipedia.org/wiki/Silver_City_Airways&quot;&gt;Silver City Airways&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Channel_Air_Bridge&quot;&gt;Channel Air Bridge&lt;/a&gt;.  In other words, your car travelled with you on the same plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On that route, sea ferries (and hovercraft) eventually killed them off financially.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do similar scheduled air ferries, for civilian cars and their passengers, still exist anywhere in the world?  If not, why?&lt;/strong&gt;  Is the reason just financial, or are there no suitable planes any more, or did new safety or security rules make it impossible to operate them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They would seem well suited to short hops like the Scottish islands, islands off British Columbia or Alaska, Indonesia, the Caribbean islands, and so on.  Especially in locations where the sea crossing is rough and unreliable.&lt;/p&gt;&#xA;" OwnerUserId="2322" LastEditorUserId="2322" LastEditDate="2014-05-11T03:15:07.937" LastActivityDate="2014-05-12T14:14:12.783" Title="Do &quot;air ferries&quot; for civilian vehicles still exist?" Tags="&lt;passenger&gt;&lt;cargo&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3823" PostTypeId="2" ParentId="3822" CreationDate="2014-05-11T03:33:00.117" Score="7" Body="&lt;p&gt;There are a number of suitable airplanes - C-130 Hercules, C-17 Globemaster, C-5 Galaxy, AN-124, up to the rather monstrous An-225 Mriya. Cargo versions of airliners don't usually handle vehicles - they are designed for palletized cargo while the above cargo planes have ground-level ramps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to fly with your car somewhere it's just a matter of calling someone who owns one of these airplanes and putting down your no-limit credit card. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you surmised, the reasons they don't operate scheduled service is financial - boats are much cheaper, and not enough people want to go where a boat is impractical.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-05-11T03:33:00.117" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3824" PostTypeId="1" AcceptedAnswerId="3825" CreationDate="2014-05-11T03:55:02.560" Score="4" ViewCount="2332" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight&quot;&gt;how-much-is-the-minimum-safe-distance-between-two-planes-in-flight&lt;/a&gt; and realized part of it confused me (or maybe I'm just tired.)&lt;/p&gt;&#xA;&lt;p&gt;In a low- or no-visibility environment (i.e. under IFR rules AND conditions), who is responsible for separation of planes in flight?&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d2302efbd7d0368b9999a00eba1d3f0a&amp;amp;node=14:2.0.1.3.10.2.4.6&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§91.111 Operating near other aircraft&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d2302efbd7d0368b9999a00eba1d3f0a&amp;amp;node=14:2.0.1.3.10.1.4.7&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§91.13 Careless or reckless operation&lt;/a&gt; are both shown in that question/answer, but if a flight is under ATC guidance, are they (ATC) or the Pilot-In-Command (PIC) responsible?&lt;/p&gt;&#xA;&lt;p&gt;I'm most interested in the U.S. (FAA Regs), but discussions of other regulatory bodies would be fine.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2021-05-12T10:00:09.917" LastActivityDate="2021-05-12T10:00:09.917" Title="Who is responsible for aircraft separation in IFR (limited/no visibility)?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="3825" PostTypeId="2" ParentId="3824" CreationDate="2014-05-11T04:02:22.373" Score="10" Body="&lt;p&gt;ATC is always responsible for IFR-IFR separation, regardless of weather conditions. That is their primary mandate, and all other services are provided on a workload-permitting basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In visual meteorological conditions, pilots of IFR aircraft are &lt;em&gt;also&lt;/em&gt; responsible for seeing and avoiding other aircraft. But for IFR traffic of course this is not always possible, since the aircraft may be going in and out of the clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a loss of separation (at worst, a collision) occurs between two IFR aircraft, ATC would be held responsible (assuming the pilots followed ATC's instructions). If analysis indicates the pilots could have seen each other, they would also be held responsible.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="946" LastEditDate="2014-11-16T17:28:23.280" LastActivityDate="2014-11-16T17:28:23.280" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3826" PostTypeId="1" AcceptedAnswerId="3828" CreationDate="2014-05-11T04:05:11.890" Score="16" ViewCount="4813" Body="&lt;p&gt;Are hot-air balloon pilots ever required to file flight plans? (can they file?)&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="1467" LastEditDate="2016-05-25T10:37:34.853" LastActivityDate="2016-08-01T06:43:52.013" Title="Do hot air balloon pilots file flight plans?" Tags="&lt;air-traffic-control&gt;&lt;flight-plans&gt;&lt;balloon&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3827" PostTypeId="1" AcceptedAnswerId="3829" CreationDate="2014-05-11T04:13:26.630" Score="9" ViewCount="17856" Body="&lt;p&gt;So there are some types of aircraft that can land under auto-pilot (or is that a trope?). Can those same planes go from stop (at the gate) to in-the-air flight without a pilot actually touching a control column/flight-stick?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Caveats: I'm not talking about UAV's. Also, I'm not concerned about &quot;would you,&quot; but rather &quot;could you.&quot;&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="247" LastEditDate="2014-05-11T10:53:47.830" LastActivityDate="2014-05-11T13:16:28.050" Title="Can any aircraft take off using auto-pilot?" Tags="&lt;autopilot&gt;&lt;takeoff&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ClosedDate="2014-05-12T15:01:32.383" ContentLicense="CC BY-SA 3.0" />
  <row Id="3828" PostTypeId="2" ParentId="3826" CreationDate="2014-05-11T04:40:26.737" Score="10" Body="&lt;p&gt;A quick look at the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/ac91-71.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA rules regulating hot air balloons&lt;/a&gt; makes it sound like, in the USA, they can enter any sort of airspace provided they can do it safely.  So, theoretically, they could file a flight plan or at least alert local ATC to their activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of that being said, having been involved in hot air balloon operations before, I think it would not be terribly feasible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, flying a hot air balloon outside of Visual Flight Rule conditions (being able to see several miles) would be extremely dangerous, so you wouldn't need to file a flight plan for that.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, you generally only want to fly a hot air balloon in very sparsely populated areas (Class G airspace), and while you could have a flight plan there really isn't a need.  A more congested area (Class B or Class A) would be extremely dangerous to navigate in a hot air balloon.  It's pretty hard to get out of the way, since controlling where you are going is...iffy sometimes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in summary, yes it could be done, but in the vast majority of cases there's little need to do it.  Other than to just alert local ATC that you will be in the area.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="14957" LastEditDate="2016-08-01T06:43:52.013" LastActivityDate="2016-08-01T06:43:52.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3829" PostTypeId="2" ParentId="3827" CreationDate="2014-05-11T04:48:11.190" Score="5" Body="&lt;p&gt;If you are asking if a plane can be taken from the gate all the way to the sky by auto-pilot I'm quite certain the answer is no.  Not because a plane can't configure itself for take off and power up the engines (I'm quite certain it can, though I would defer to more knowledgeable people for that).  Not for that reason, but rather because there is no system in place to electronically guide an aircraft through a series of taxiways all the way to the base of the runway so that it can line up to take off in the first place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind, ATC gives a lot of instructions for ground operations, funnelling aircraft this way and that via taxiway A through Z.  They'd have no way of telling an auto-pilot about these directions, there's no computer to send out signals and there is no voice recognition build into the plane.  If you told the pilots, they would have no way to input the instructions into the autopilot, nor would the autopilot know what to do if it ever received such instructions.  It just isn't designed to follow taxiways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, beyond just taxiway layout, there are a lot of planes in close proximity on the ground, plus bunches of other important vehicles (fire trucks, fuel trucks, de-icers, etc.)  Steering around all of those, faultlessly, would be quite the feat.  We've only just gotten to the point where &lt;a href=&quot;https://www.youtube.com/watch?v=jV51BGIzkwU&quot; rel=&quot;nofollow&quot;&gt;a vehicle can drive across open terrain without crashing itself&lt;/a&gt;,  I think a plane navigating an airport (and doing it while minding ATC) is a bit of a ways off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Raidri's video does a much better job of &lt;a href=&quot;https://www.youtube.com/watch?v=dk3oc1Hr62g&quot; rel=&quot;nofollow&quot;&gt;showing the current state of driver less vehicles,&lt;/a&gt; and his comment is correct. I did underestimate how good the systems are these days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, I'm not changing my answer.  There still, currently, is no way to convey ATC instructions to the aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a point of clarification: I saw the question as asking about technology in it's current state.  Will we eventually be able to do this.  Heck yes, absolutely.  A great deal of the technology is in place and what's left is either right on the horizon or close to it.  FAA clearance will probably take some time, but we'll get there.  I was mainly answer the question from the perspective of modern tech and what is currently ready to be installed on a plane.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-05-11T13:16:28.050" LastActivityDate="2014-05-11T13:16:28.050" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3830" PostTypeId="2" ParentId="3827" CreationDate="2014-05-11T06:06:01.183" Score="4" Body="&lt;p&gt;&quot;could&quot; you : yes. After pushback (and away from the gate area in general) airports are more-or-less obstacle free. Modern GPS is plenty accurate enough to follow a taxiway sequence up to the hold-short line (this is a &lt;em&gt;much&lt;/em&gt; simpler problem than driving an automated car around town [1]). A cheap rangefinder in the nose would prevent goosing the plane in front. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the plane is on the active runway it's just a matter of configuring a few things and running the power up. No problem at all with today's technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;would&quot; you: no. Such a system would be rather expensive, someone has to program it, and it provides no particular advantages over having the pilot steer it following a $5 map, or at smaller airports just the signs beside the taxiway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1] Support vehicles at an airport are not really an issue: aircraft have absolute, unquestioned right-of-way in much the same manner as freight trains. Even the fire department waits for the tower to approve crossing a runway.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-05-11T06:06:01.183" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3831" PostTypeId="1" AcceptedAnswerId="3840" CreationDate="2014-05-11T07:15:33.687" Score="2" ViewCount="2322" Body="&lt;p&gt;I know in most homes your local transformer provides a 50Hz or 60Hz power source. So all your hairdryers, dishwashers etc. are built to consume 50Hz or 60Hz power at 110&amp;nbsp;volts or 220&amp;nbsp;volts, depending on where you live in the world.  On the aircraft engine generators use a much higher frequency (400Hz). Why is this? &lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="1467" LastEditDate="2016-03-31T13:49:08.293" LastActivityDate="2016-03-31T13:49:08.293" Title="Why do jet generators produce a higher frequency power then household electricity?" Tags="&lt;electrical-system&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-05-12T15:02:41.597" ContentLicense="CC BY-SA 3.0" />
  <row Id="3832" PostTypeId="1" AcceptedAnswerId="3833" CreationDate="2014-05-11T07:25:48.290" Score="12" ViewCount="1140" Body="&lt;p&gt;I know in a building we have lightning rods that conduct a lightning strike into the earth, but for an aircarft there is no ground to 'ground' so I assume the lightning enters and passes through the aircraft. Therefore, since some areas must have high resistance paths of protection, for example a path through the antennas or main electronics bay, they must be an alternate low resistance path capable of conducting a very high power flow with minimum damage and burning. What is this design path?&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="1467" LastEditDate="2016-03-31T13:50:19.970" LastActivityDate="2016-03-31T13:50:19.970" Title="What is the low resistance design path in an aircraft to withstand a lightning strike?" Tags="&lt;aircraft-design&gt;&lt;weather&gt;&lt;electrical-system&gt;&lt;lightning&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3833" PostTypeId="2" ParentId="3832" CreationDate="2014-05-11T08:23:06.030" Score="13" Body="&lt;h2&gt;The conductive exterior body&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Almost all aircraft have metal bodies, the electric current flows through the exterior metal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft with composite hulls can have conducting material added to the composites to provide a path for lightning. This is typically a metal mesh.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some smaller composite aircraft, lacking this sort of provision, simply cannot fly near clouds or anywhere where there is a risk of lightning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vV6Cv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;em&gt;&lt;sup&gt;photo by Boeing - see references&lt;/sup&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The outer conducting surface acts as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Faraday_cage&quot; rel=&quot;nofollow noreferrer&quot;&gt;Faraday cage&lt;/a&gt; preventing the high voltages and currents from affecting the interior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/meI6c.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;em&gt;a Faraday cage &lt;sub&gt;photo by &lt;a href=&quot;http://commons.wikimedia.org/wiki/User:Antoinetav&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antoine Taveneaux&lt;/a&gt;&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is estimated that on average, each airplane in the U.S. commercial&#xA;  fleet is struck lightly by lightning more than once each year.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Initially, the lightning will attach to an extremity such as the nose&#xA;  or wing tip. The airplane then flies through the lightning flash,&#xA;  which reattaches itself to the fuselage at other locations while the&#xA;  airplane is in the electric &quot;circuit&quot; between the cloud regions of&#xA;  opposite polarity. The current will travel through the conductive&#xA;  exterior skin and structures of the aircraft and exit off some other&#xA;  extremity, such as the tail. Pilots occasionally report temporary&#xA;  flickering of lights or short-lived interference with instruments.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Every circuit and piece of equipment that is critical or essential to&#xA;  the safe flight and landing of an aircraft must be verified by the&#xA;  manufacturers to be protected against lightning in accordance with&#xA;  regulations set by the Federal Aviation Administration (FAA) or a&#xA;  similar authority in the country of the aircraft's origin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.scientificamerican.com/article/what-happens-when-lightni/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scientific American - What happens when lightning strikes an airplane?&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Planes are now built to absorb 250,000 amps, whereas the average&#xA;  strike generates 32,000 amps.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;It only gets really serious when the radome [nose cone] is struck,&#xA;  the only part of the plane's shell not made of metal, as this is where&#xA;  the radar is located. But nose cones have special lightning conductors&#xA;  for just this reason.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.theguardian.com/world/shortcuts/2012/may/16/worried-lightning-striking-plane&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Guardian - Should you be worried about lightning striking your plane?&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 787 flight test team gathered the unexpected data last month after&#xA;  one of the Dreamliner test aircaft was struck by lightning. Unlike&#xA;  traditional aluminum aircraft where the entire aircraft is conductive,&#xA;  on a composite airplane the charge from a lightning strike would find&#xA;  its way to the conductive parts such as wiring or hinges. In order to&#xA;  avoid the risk of the charge damaging these kinds of parts, Boeing &#xA;  had to add conductive material to the composites in order to provide a&#xA;  pathway for lightning strikes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.wired.com/2010/06/boeing-787-withstands-lightning-strike/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 787 Withstands Lightning Strike&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Other references&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing - Lightning Strikes, Protection, Inspection and Repair&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://seattletimes.nwsource.com/news/business/links/boeinglightni_b.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Protecting the 787&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.compositesworld.com/articles/lightning-strike-protection-strategies-for-composite-aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lightning strike protection strategies for composite aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-05-12T16:28:21.643" LastActivityDate="2014-05-12T16:28:21.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3834" PostTypeId="2" ParentId="3827" CreationDate="2014-05-11T10:05:36.223" Score="2" Body="&lt;p&gt;If you're simply asking &lt;em&gt;&quot;does this exist today?&quot;&lt;/em&gt;, then the answer is simply no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe there are no automatic take-off systems currently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't forget drones are flown by the remote human pilots; I don't think even they have an automatic takeoff system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding &lt;em&gt;&quot;would it be technically possible as an experiment?&quot;&lt;/em&gt;, Paul has explained the situation.&lt;/p&gt;&#xA;" OwnerUserId="3288" LastEditorUserId="19" LastEditDate="2014-05-11T11:29:27.057" LastActivityDate="2014-05-11T11:29:27.057" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3836" PostTypeId="1" CreationDate="2014-05-11T11:04:36.387" Score="14" ViewCount="1031" Body="&lt;p&gt;Whenever a design company is obtaining an STC for an aircraft (Supplemental Design Certificate) for an electrical installation, one of the required tests to obtain the STC is a lightning strike test. The test is needed to show that the electronics installed can withstand a lightning strike without degrading their performance or inducing degradations into other systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can't position the aircraft on ground waiting for a lightning bolt to hit like 'Doc' in 'Back to the Future', so how do design companies, or engine manufacturers, etc. simulate a lightning strike and draw conclusive results that the system with withstand actual lightning?&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="8730" LastEditDate="2016-01-31T21:23:43.153" LastActivityDate="2016-01-31T21:23:43.153" Title="How is an on ground lightning strike test conducted?" Tags="&lt;safety&gt;&lt;weather&gt;&lt;avionics&gt;&lt;aircraft-certification&gt;&lt;lightning&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3837" PostTypeId="2" ParentId="3836" CreationDate="2014-05-11T11:30:28.383" Score="4" Body="&lt;p&gt;So, &lt;a href=&quot;http://youtu.be/0Nly5GbDHfA&quot; rel=&quot;nofollow&quot;&gt;Lightning Strike Test - Panthera Aircraft by Pipistrel - Episode 1&lt;/a&gt; is a short video showing how Pipistrel did it. I really want to be able to push that button! :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.nasa.gov/larc/lightning-tests/&quot; rel=&quot;nofollow&quot;&gt;page&lt;/a&gt; is a video and article showing how NASA does it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://www.scientificamerican.com/article/what-happens-when-lightni/&quot; rel=&quot;nofollow&quot;&gt;Scientific American&lt;/a&gt; article about the why's more than the how's.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-05-11T11:30:28.383" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3838" PostTypeId="1" AcceptedAnswerId="5165" CreationDate="2014-05-11T16:12:54.887" Score="8" ViewCount="1605" Body="&lt;p&gt;Landing is possible down to 150 ft visibility and no useful vertical visibility using CAT IIIb ILS. This relies on ILS not only for navigating to the runway, but also for maintaining runway centreline during roll out down to taxi speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is it also possible to &lt;em&gt;take off&lt;/em&gt; in such weather and if so, how is it done?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(edit) Answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1910/airline-low-visibility-takeoff-operations&quot;&gt;Who authorizes low visibility takeoff operations for airlines, and what is required?&lt;/a&gt; mentions take off is possible down to 300 ft RVR with a &quot;takeoff guidance system&quot;. So more specifically, how does that work?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-12-30T05:02:01.093" Title="What is needed to take off in CAT IIIb weather and how is it done?" Tags="&lt;takeoff&gt;&lt;instrument-procedures&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3839" PostTypeId="2" ParentId="3836" CreationDate="2014-05-11T17:25:37.603" Score="8" Body="&lt;p&gt;You create your own lightning. You can do that with an &lt;a href=&quot;http://en.wikipedia.org/wiki/Impulse_generator&quot; rel=&quot;noreferrer&quot;&gt;impulse generator&lt;/a&gt;. Here's what a smaller one looks like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oIeee.jpg&quot; alt=&quot;impulse generator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if that's what is used for the certificates but it certainly one way to test against lightning strikes (provided that you can generate a high enough voltage).&lt;/p&gt;&#xA;" OwnerUserId="2325" LastActivityDate="2014-05-11T17:25:37.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3840" PostTypeId="2" ParentId="3831" CreationDate="2014-05-11T18:29:51.267" Score="3" Body="&lt;p&gt;This is a bit speculative, and if I am wrong, I will stand corrected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on my little experience with power plant gas turbines, the frequency depends on the rpm of the turbine and the number of poles of the generator. A power plant turbine runs at 3000 rpm (for 50 Hz) or 3600 rpm (for 60 Hz), with two poles (this is the most reliable design, and works with turbines with rotors up to about 4 m diameter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft APU is much smaller, and will run at higher for optimized power output. So, for the 400 Hz, you would have, for example, 12000 rpm and 4 poles (or 24000 rpm and 2 poles).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It already has been mentioned that transformers can be way smaller and lighter for higher frequencies, and it may also be that the higher freqencies of the harmonics cause less interference with other systems of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The speed of the generator is held constant, regardless of the engine's rpm, by the use of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Constant_speed_drive&quot; rel=&quot;nofollow&quot;&gt;Constant Speed Generator&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Constant_speed_drive#Integrated_Drive_Generator&quot; rel=&quot;nofollow&quot;&gt;Integrated Drive Generator&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2327" LastEditorUserId="1696" LastEditDate="2014-05-13T23:15:06.030" LastActivityDate="2014-05-13T23:15:06.030" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3841" PostTypeId="2" ParentId="3733" CreationDate="2014-05-11T18:40:08.090" Score="9" Body="&lt;p&gt;On the 747 with P&amp;amp;W engines at least, there was a procedure where a mechanic could manually open and close the start valve at the engine if energizing the start valve from the cockpit failed. Obviously you had to have communication with the mechanic to tell him when to close it. I never had to do it for real, and only a few times in the sim.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-11T18:40:08.090" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3842" PostTypeId="1" AcceptedAnswerId="3891" CreationDate="2014-05-12T00:41:35.980" Score="8" ViewCount="1717" Body="&lt;p&gt;I've been researching the history of pre-jet aircraft and I've come across several famous, and not so famous, blended-wing aircraft. The idea seemed to show promise but never really caught on, even for a limited span of time or confluence of technological factors e.g. weight vs engine power etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Just to be clear, I'm not interest in flying wing and/or tailless aircraft whose early problems are well known, but rather those designs that have tails but have a fuselage shaped to produced a significant component of lift.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just a few of the designs I've stumbled across:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Burnelli_CBY-3&quot;&gt;Burnelli CBY-3&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://freespace.virgin.net/john.dell/cowing/cowing.html&quot;&gt;Cunliffe-Owen OA-1&lt;/a&gt; (Burnelli license)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.century-of-flight.net/Aviation%20history/flying%20wings/early%20US%20flying%20wings.htm&quot;&gt;French de Monge 7.4&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dieselpunks.org/profiles/blogs/plywood-monster&quot;&gt;Soviet LK-1 a.k.a. Fanera-2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are quite a few more I don't have handy web links for. Junkers did a couple that would probably qualify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The large number of designs from all over the world show that the basic idea offered promise but all the designs eventually went no where despite being tried in many countries, economies and even political systems. That in turn seems strange because in the 1920s-early-1940s, lift seemed more important than speed for larger multiengine aircraft i.e. just getting a load airborne at all was worth quite a few other tradeoffs. As engines grew more powerful that tradeoff lessened but for at least 15-20 years a high lift design should have been more desirable than a high speed one for larger aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The failure of many different designers over the course of three decades to make the blended wing work suggest to me that the basic idea has some inherent disadvantage/s that outweighed any gains. Unfortunately, none of the resources I have consulted offer any clues to why the designs did not &quot;take off.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect the designs showed some rapid onset of stall of instabilty but that's just an uninformed hunch on my part. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any clues?&lt;/p&gt;&#xA;" OwnerUserId="2300" LastEditorUserId="23223" LastEditDate="2019-09-12T09:52:59.160" LastActivityDate="2019-09-12T09:52:59.160" Title="What were the disadvantages of early prop driven blended-wing aircraft?" Tags="&lt;propeller&gt;&lt;airworthiness&gt;&lt;blended-wing&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3843" PostTypeId="2" ParentId="3566" CreationDate="2014-05-12T04:46:52.043" Score="2" Body="&lt;p&gt;There is no requirement to have the certificate with you on board during flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The holder of a radio authorization shall, at the request of an inspector appointed pursuant to the Act, show the radio authorization or a copy thereof to the inspector within 48 hours after the request.   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source:&lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/sor-96-484/page-8.html#h-35&quot; rel=&quot;nofollow&quot;&gt;Radiocommunication Regulations, s 38&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="100" LastEditDate="2014-05-13T14:53:16.423" LastActivityDate="2014-05-13T14:53:16.423" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3844" PostTypeId="1" AcceptedAnswerId="3851" CreationDate="2014-05-12T12:52:58.533" Score="22" ViewCount="13313" Body="&lt;p&gt;I'm merely an amateur simulator (X-Plane) pilot. On a flight yesterday the airspeed indicator stopped working. After the initial panic I remembered reading something about pitot tubes freezing, found the pitot heating switch, and turned it on. The problem was resolved immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This led me to think: Is there a good reason to not turn pitot heating on before take-off, and leave it on for the entire flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm flying a Sud Aviation SE 210 Caravelle&lt;/p&gt;&#xA;" OwnerUserId="2331" LastEditorUserId="2331" LastEditDate="2018-01-30T08:28:36.807" LastActivityDate="2018-01-30T08:28:36.807" Title="Why turn off pitot tube heating?" Tags="&lt;pitot-static&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3845" PostTypeId="2" ParentId="3844" CreationDate="2014-05-12T13:08:05.817" Score="2" Body="&lt;p&gt;Although pitot heat is quite reliable, it can burn out much like an incandescent light bulb.  Why waste its useful life without immediate reason?  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-05-12T13:08:05.817" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3846" PostTypeId="1" CreationDate="2014-05-12T13:41:37.253" Score="8" ViewCount="898" Body="&lt;p&gt;In Europe some commercial airlines--such as Wizz Air and Air Berlin--charge licensed co-pilots to sit in the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is called &quot;pay to fly&quot; or &quot;Line training&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it allowed in the USA ? Is there a FAA regulation regarding that?&lt;/p&gt;&#xA;" OwnerUserId="2332" LastEditorUserId="790" LastEditDate="2014-05-12T15:03:43.087" LastActivityDate="2014-07-25T18:28:07.407" Title="Is line training (pay to fly) allowed in the USA?" Tags="&lt;flight-training&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3847" PostTypeId="2" ParentId="3822" CreationDate="2014-05-12T14:14:12.783" Score="4" Body="&lt;p&gt;To answer the question directly:  No, there are no scheduled automobile ferrys at this time.  Can certain aircraft carry something the size and weight of a car?  Of course, see other replies here for a list of some of the planes with this capability.  Why not?  The answer is, as you suspect, financial.  In most circumstances it is cheaper to buy or rent a vehicle where you need one.&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-05-12T14:14:12.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3848" PostTypeId="2" ParentId="3844" CreationDate="2014-05-12T14:49:52.617" Score="15" Body="&lt;p&gt;I'm not sure what kind of airplane that you are flying in the simulator, but the checklists for jets typically &lt;strong&gt;do&lt;/strong&gt; have you turn the pitot heat on just before takeoff and leave it on until after landing, just so that this is less likely to happen.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Update: I found a &lt;a href=&quot;http://sudaviation.com/wp-content/uploads/2012/09/checklistnormal1.pdf&quot;&gt;French checklist&lt;/a&gt; for the Caravelle and it says to turn on the pitot heat before takeoff:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rechauffage Pitot.....MARCHE&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-05-12T15:37:53.453" LastActivityDate="2014-05-12T15:37:53.453" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3849" PostTypeId="2" ParentId="3733" CreationDate="2014-05-12T15:13:53.110" Score="20" Body="&lt;p&gt;Perusing the A380 Training Guide, Edition 01, 01 Sep 2008, Section 5 - Engine Starts, Subsections 5.8.6 (Engine Start Valve Stuck Closed),&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.8.6 Engine Start Valve Stuck Closed&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;ECAM actions – ENGINE MASTER OFF.&lt;/li&gt;&#xA;  &lt;li&gt;Check MEL, and in conjunction with, advise LAE of situation in preparation for Start Valve Manual Operation.&lt;/li&gt;&#xA;  &lt;li&gt;For Start Valve Manual Operation on Engines #2 and #4, the adjacent engine (if already running) will require shutdown, to enable LAE’s&#xA;  access to the manual start override procedure on the port side of the&#xA;  affected engine.&lt;/li&gt;&#xA;  &lt;li&gt;As the CAB Pb on the RMP is common to the Cockpit, Ground and Cabin Crew, advise the Cabin Crew to refrain from using the Cabin Interphone&#xA;  during the procedure.&lt;/li&gt;&#xA;  &lt;li&gt;When ready, accomplish normal engine start sequence:&lt;br&gt;&#xA;  a)    Engine Start Selector to IGN/START.&lt;br&gt;&#xA;  b)    Engine Master Lever to ON.&lt;br&gt;&#xA;  c)    Command LAE to OPEN START VALVE AND KEEP OPEN.&lt;br&gt;&#xA;  d)    At 50%N3, command LAE, START VALVE CLOSE.&lt;br&gt;&#xA;  e)    Monitor engine parameters closely until stabilized.  &lt;/li&gt;&#xA;  &lt;li&gt;Advise Cabin Crew upon completion of procedure.  &lt;/li&gt;&#xA;  &lt;li&gt;In flight, only windmilling start will be available.  &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Glossary&lt;/strong&gt; (&lt;em&gt;correct if needed, please&lt;/em&gt;):&lt;br&gt;&#xA;ECAM = Electronic Centralised Aircraft Monitor&lt;br&gt;&#xA;LAE = Licensed Aircraft Engineer&lt;br&gt;&#xA;CAB = Cabin&lt;br&gt;&#xA;Pb = Pushbutton&lt;br&gt;&#xA;RMP = Radio Management Panel&lt;br&gt;&#xA;IGN = Ignition&lt;br&gt;&#xA;N1/N2/N3 = N1 is LP (Low Pressure stage), N2 is IP (Intermediate Pressure stage), N3 is HP (High Pressure stage)&lt;br&gt;&#xA;MEL = Minimum Equipment List&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;ECAM will display &quot;ENG MASTER X ........ OFF&quot; &lt;em&gt;(X will be the engine with stuck valve)&lt;/em&gt;&#xA;&lt;a href=&quot;http://www.efbdesktop.com/engines/sys-5.3.1.html&quot;&gt;&lt;em&gt;(A320 display, only shows two engines, instead of four)&lt;/em&gt;&lt;/a&gt; &lt;em&gt;(The message will appear in the lower left quadrant.)&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Check the Minimum Equipment List (MEL) to determine if loss of engine is GO, GO IF, or NO GO, if failure is not in the MEL, it is classified by default as NO GO. Advise the on-site Licensed Aircraft Engineer (LAE) of the warning message in preparation for completing the Start Valve Manual Operation procedure.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the engine with the stuck valve is #2 (left side inboard) or #4 (right side outboard), the adjacent engine will be required to be shutdown before commencing the manual start procedure. &lt;em&gt;(This is because the engineer has to access the left side of the engine and for safety's sake the other engine, which would be gehind him must be shut down. If the fault is on the left outboard (#1) then the engineer would be on the far side of the engine from the #2 so #2 does not need to be shutdown.)&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Since the Cabin Pushbutton (CAB Pb) on the Radio Management Panel (RMP) is common to the Cockpit, the Cabin Crew area AND the Ground circuit, the pilot should advise the Cabin Crew to not use the Cabin Interphone during the procedure. &lt;em&gt;(If the pilot and the engineer are discussing starting the engine (or not) they don't want a flight attendant to be talking about starting pre-flight stuff at the same time, if the engineer heard the word start, he might wrongly assume it was the pilot.)&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When pilot and engineer are ready, begin the normal engine start sequence with changes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) Turn the Engine Start Selector to IGN/START. &lt;a href=&quot;http://www.efbdesktop.com/engines/sys-5.5.0.html&quot;&gt;&lt;em&gt;(This is a panel from an A320, so only two engines are shown.)&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) Flip the Engine Master Lever &lt;em&gt;(For the faulted engine)&lt;/em&gt; to ON. &lt;a href=&quot;http://www.efbdesktop.com/engines/sys-5.5.0.html&quot;&gt;&lt;em&gt;(This is a panel from an A320, so only two engines are shown.)&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) Over the interphone, command the engineer to manually open the start valve and keep it open. &lt;em&gt;(I haven't yet looked for and found a schematic for an example engine, sorry. As shown in other diagrams/answers, it might be a socket wrench, etc.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;d) Watch the Engine Warning Display. &lt;a href=&quot;http://www.efbdesktop.com/engines/sys-5.3.2.html&quot;&gt;&lt;em&gt;(Again, A320, only two engines.)&lt;/em&gt;&lt;/a&gt; &lt;a href=&quot;http://captaindavea380.files.wordpress.com/2014/03/dsc08551.jpg&quot;&gt;&lt;em&gt;(This is an A380, showing N3)&lt;/em&gt;&lt;/a&gt; Once N3 is spun up to 50%, over the interphone, command the engineer to manually close the start valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;e) Monitor the engine parameters closely until all are properly stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;f) After the engineer has closed up the engine and vacated the area, start the other engines, if one was shut down per step 3.&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Over the cabin interphone, notify the cabin crew that the procedure is complete. &lt;em&gt;( so they can resume using the interphone if needed. )&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the engine failed in-flight and upon restart a stuck valve warning was shown, all of the above would not be possible. At that time, the only way to restart the engine would be to attempt a windmill start (using the flow of air through the engine to turn the engine), there are other procedures for that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Also, I do not yet have the engine schematics to show what the LAE actually does.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2014-05-17T11:37:04.287" LastActivityDate="2014-05-17T11:37:04.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3850" PostTypeId="2" ParentId="3815" CreationDate="2014-05-12T16:37:00.773" Score="17" Body="&lt;p&gt;First of all, there is the question of demand. There aren't enough cases where a very heavy load needs to be moved to a remote location by air. There are probably even fewer where there are funds to actually pay for this option. The An-225 is currently the largest aircraft in operation, and it was only constructed under special circumstances. Although has certainly found use, they still haven't even found the funds to finish a second one which is partially built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When this option is needed today, helicopters are deployed on cargo aircraft to the area. The helicopters may have to make multiple trips but can do the job. So the subset of cases is even smaller; where heavy cargo needs to be delivered to a remote area and also cannot be split into shipments that helicopters can handle. Deploying a large airship in this manner is also much harder. Either the airship would have to fly itself there, which could take a long time, or it would have to be reduced to a transportable size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airship would also need to be protected from the weather somehow. This could require either a very large (and expensive) hangar. Without a hangar, the airship must be tethered, and restraining such a large surface area in the wind would be difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind would also affect operation of the airship. Helicopters are of course limited by weather conditions, but wind would have a much greater effect on a large and slow airship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airship could be fairly easily collapsible, it would solve the issues of storage and transportation. However, this is not a simple problem to solve. This would require a large development budget. If you are comparing this to the cost of the 787 development, where are you going to find buyers for 1000 of these airships in order to break even and make them affordable?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue is that there needs to be a market for this kind of transportation, which currently competes at least partially with existing helicopters. Why invest in a new type of vehicle when the current option works fine for most cases?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-09T14:32:55.250" LastActivityDate="2015-04-09T14:32:55.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3851" PostTypeId="2" ParentId="3844" CreationDate="2014-05-12T16:53:44.460" Score="10" Body="&lt;p&gt;The aircraft checklist will determine when the pitot heat should be on. Strictly speaking, if the checklist says it should be on, the only reason it should not be on is if the system is inoperative or is causing some issue (if the generator system fails it will drain the battery, as falstro commented). The checklist linked by Lnafziger has the pitot heat ON before takeoff and OFF after landing. Other times it may be &quot;as required&quot; by conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pitot heat makes sure the pitot system remains free of ice. Failed airspeed, especially in IFR conditions, can be serious. The failure may not be obvious, leaving you to stall/overspeed. Leaving the heat on can cause the system to overheat. While some systems automatically protect against this, not all will (especially with smaller aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Checklists for larger jets also seem to have probe heat on before taxi and off right before shutdown. The reason for this is probably safety. Modern aircraft rely heavily on pitot static systems. AF447 crashed partially due to icing on the pitot tubes. Why leave it off and run the risk of icing? The cost of leaving it on is fairly low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On smaller aircraft where the pilot may even be able to see the pitot tubes, the situation may be different. These aircraft have less automation, and the cost of repairing a pitot heat system is higher relative to the rest of the aircraft's maintenance. However, the issue of safety remains.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-05-13T22:29:33.560" LastActivityDate="2014-05-13T22:29:33.560" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3852" PostTypeId="2" ParentId="3842" CreationDate="2014-05-12T17:57:20.630" Score="0" Body="&lt;p&gt;Looking through your first link about the CBY-3, it seems there may be &lt;a href=&quot;http://www.aircrash.org/burnelli/neam1.htm&quot; rel=&quot;nofollow&quot;&gt;political reasons&lt;/a&gt; for the failure of this design. To this day, many organizations still refuse to acknowledge the merits of the design. Part of the issue is probably the interests of much larger companies which were already deeply entrenched by this time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your second link is related to the Burnelli designs, and the page also offers this explanation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Cunliffe-Owen OA-1 Flying Wing was almost certainly too late to be a success in the civil marketplace. By the time it was ready to fly it was already 4 or 5 years behind the times in terms of performance and economy.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-12T17:57:20.630" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3853" PostTypeId="1" AcceptedAnswerId="3855" CreationDate="2014-05-12T18:42:08.223" Score="8" ViewCount="22607" Body="&lt;p&gt;Why do planes have cross-feed switches or circuits? Are they to move contents of one tank to another (feed the tank) or to supply the engine with fuel from left side to right or vice versa (feed the engine)?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="572" LastEditDate="2015-02-19T09:37:46.887" LastActivityDate="2020-05-22T10:26:49.480" Title="Why do planes have cross-feed switches or circuits?" Tags="&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3854" PostTypeId="2" ParentId="3103" CreationDate="2014-05-12T18:59:12.800" Score="1" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Transformer#Effect_of_frequency&quot; rel=&quot;nofollow&quot;&gt;transformer&lt;/a&gt; that converts the same power on a higher frequency is much smaller and lighter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A modern design of the compact isolating power supply (say 220 V 50 Hz to 12 V DC) would often include a frequency converter, then a high frequency transformer, then a rectifier (a big 50 Hz transformer is now uncommon). But maybe the standard has settled before this complex electronics became available, or maybe because higher frequencies may be source of interference.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2015-06-24T14:38:27.917" LastActivityDate="2015-06-24T14:38:27.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3855" PostTypeId="2" ParentId="3853" CreationDate="2014-05-12T19:15:31.657" Score="12" Body="&lt;p&gt;The fuel system in aircraft generally includes a left and right tank within the corresponding wings. Each tank generally provides fuel to the engines on that wing. The crossfeed valve is used to temporarily connect the two sides of the system. This system allows the shortest route for the fuel and keeps the systems separate, so a leak on one side cannot drain the entire system. The crossfeed valve is generally kept shut for this reason. A couple scenarios illustrate when opening the valve might be necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To keep the plane balanced, both wing tanks should have about the same amount of fuel. However, for various reasons, they could become unbalanced. The crossfeed valve allows fuel to flow from the tank with too much fuel to the tank with less fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another scenario would be the loss of an engine. In a twin-engine airplane, the remaining engine would need to be able to draw fuel from both wing tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: especially in larger aircraft, fuel systems can be much more complicated, with multiple tanks in each wing and also in the fuselage. Fuel transfer also becomes more complicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the 737 as an example, this is the fuel system control panel with the crossfeed switch in the center. With the crossfeed valve open, turning off the fuel pumps on one tank will cause more fuel to be drawn from the tanks on the other side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bxm3f.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-12T19:15:31.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3856" PostTypeId="2" ParentId="3815" CreationDate="2014-05-12T19:19:48.700" Score="6" Body="&lt;p&gt;Helium is not without its own issues. While it isn't a fire hazard it is a limited resource. Let &lt;a href=&quot;http://www.popularmechanics.com/science/health/med-tech/why-is-there-a-helium-shortage-10031229&quot;&gt;Popular Mechanics&lt;/a&gt; tell you about supply issues for helium. So any large scale industrial use of helium could drive up the price of the gas.&lt;/p&gt;&#xA;" OwnerUserId="2329" LastActivityDate="2014-05-12T19:19:48.700" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3857" PostTypeId="1" AcceptedAnswerId="3858" CreationDate="2014-05-12T19:49:47.507" Score="11" ViewCount="3601" Body="&lt;p&gt;Do seaplanes have to land in particular places or are they allowed to land pretty much anywhere there is room to land safely?&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2018-03-22T07:47:35.280" Title="Do seaplane have designated landing areas?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;seaplane&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3858" PostTypeId="2" ParentId="3857" CreationDate="2014-05-12T19:55:40.543" Score="8" Body="&lt;p&gt;Taken from &lt;a href=&quot;http://seaplanes.org/&quot; rel=&quot;noreferrer&quot;&gt;seaplanes.org&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;While most pilots assume the FAA has jurisdiction over landing areas, including water-based landing areas, the truth is much more complex. Jurisdiction rests with the person or organization that &amp;quot;owns&amp;quot; the waterway. This may be a Federal or state agency, a local government, a private corporation, or an individual. Determining who controls a waterway is the first step in determining whether it is legal to land on that body of water.&lt;/p&gt;&#xA;&lt;p&gt;A second complication enters in the picture with overriding jurisdictions, most commonly state-imposed seaplane base licensing requirements. In several states, notably Ohio, New Jersey and Indiana, seaplanes may not land unless the proposed landing area is certified as a seaplane base, regardless of whether the waterway owner provides permission or not. To determine whether this is an issue in your area, call your state aeronautics office (often a division of the state department of transportation), check the Water Landing Directory, or call SPA Headquarters (863/701-7979).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2179" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-12T19:57:18.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3860" PostTypeId="2" ParentId="3807" CreationDate="2014-05-12T22:15:06.423" Score="0" Body="&lt;p&gt;One thing to point out, electronics on planes really isn't as big of a &lt;strong&gt;safety&lt;/strong&gt; factor as the airline would have you believe, and it's becoming less and less of an issue since consumer demands are pointing towards the aircraft that allow them to be entertained while traveling, such as have WiFi.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the companies that run the phone lines it's a different story entirely. If your careening through the air at 500 knots and you make a phone call, you require the phone towers to do a lot more work receiving your call. I'm not sure why, but I remember reading that the main movement behind not using electronics while flying was really because our telephone infrastructure isn't capable of handling the excess load.&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2014-05-12T22:15:06.423" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3861" PostTypeId="1" AcceptedAnswerId="3869" CreationDate="2014-05-12T22:36:41.010" Score="14" ViewCount="2445" Body="&lt;p&gt;I'm a student pilot at a class C airport in the USA. Last weekend I did pattern work. Mostly touch and goes, but it was busy and my approaches were less than perfect so there were some go arounds and some 360s for traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being in the pattern on a busy day was a little stressful. I was constantly reading things back, changing traffic direction, switching runways R/L, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am curious to know what it's like flying in class B airspace. Are traffic patterns different from class C? Are there additional skills that pilots must have? For example, I know that I'm not even allowed to be in class B airspace as a student without a class B endorsement. &lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="14957" LastEditDate="2016-08-28T07:34:55.457" LastActivityDate="2016-09-26T15:16:03.250" Title="What is it like flying in class B airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;class-b-airspace&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3862" PostTypeId="2" ParentId="3844" CreationDate="2014-05-12T23:05:45.917" Score="9" Body="&lt;p&gt;At our airclub, the checklist for C172 shows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;... stuff ...&lt;/li&gt;&#xA;&lt;li&gt;Pitot heat on, check tube warm, turn off.&lt;/li&gt;&#xA;&lt;li&gt;... complete the walk-around... start... taxi to engine run-up... do run-up...&lt;/li&gt;&#xA;&lt;li&gt;Do final pre-take-off checks, one of the last of which is &quot;pitot heat: ON&quot;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've seen some C172 checklists that say &quot;as required&quot; instead of &quot;on&quot; near the end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no further pitot heat items on the checklist except for the &quot;after landing checklist&quot;. So we're supposed to just leave it on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During my initial training my instructor mentioned that we turn it off until just before take-off because it can overheat and fail if operated while stationary. I don't remember seeing this in the C172 operating handbook, so maybe they're just being overly cautious or something.&lt;/p&gt;&#xA;" OwnerUserId="2194" LastEditorUserId="2194" LastEditDate="2014-05-12T23:12:05.780" LastActivityDate="2014-05-12T23:12:05.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3863" PostTypeId="1" AcceptedAnswerId="3867" CreationDate="2014-05-12T23:48:23.080" Score="12" ViewCount="59069" Body="&lt;p&gt;I know that from nose to tail the aircraft is divided by STA (station). At least for Boeing and Airbus this is the case but I am not familiar with other manufacturers.  However, there is also two other dimensions that give every location of an aircraft an identifiable point location. It's obviously not x,y,z.  What is this coordinate system and approximately what does one unit along each access mean in terms of inches or centimeters?&lt;/p&gt;&#xA;" OwnerUserId="2213" LastActivityDate="2017-04-14T23:20:43.310" Title="What is the coordinate system used in an Aircraft?" Tags="&lt;commercial-aviation&gt;&lt;measurement&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3864" PostTypeId="1" AcceptedAnswerId="7933" CreationDate="2014-05-13T01:53:30.133" Score="27" ViewCount="4696" Body="&lt;p&gt;I get the feeling that if aviation was a religion and had a holy book, that book would be &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0070362408&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Stick and Rudder&lt;/em&gt;&lt;/a&gt;.  Mostly because it's often spoken of with great authority by people who have never read it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, I'm reading it right now.  And let me tell you, Wolfgang has got some &lt;em&gt;opinions&lt;/em&gt;.  Here's one of them, from Chapter 11.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The important thing to understand about the rudder pedals is that they are unnecessary; like your wisdom teeth, they serve no very good purpose but can cause much trouble.  The airplane needs no rudder pedals.  It should have no rudder pedals.  In all probability it will have no rudder pedals 10 years hence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have to give him credit: he put his money where his mouth was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DEv5s.jpg&quot; alt=&quot;Ercoupe - an airplane without rudder pedals&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the fact that it's now 2014 and rudder pedals are still very much in vogue makes me wonder:  &lt;strong&gt;Did Wolfgang Langewiesche ever change his mind about rudder pedals, or did he go to his grave defiant to the end?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="1467" LastEditDate="2015-07-14T19:00:17.330" LastActivityDate="2017-11-15T07:53:04.627" Title="Did Wolfgang Langewiesche ever change his mind about rudder pedals?" Tags="&lt;flight-controls&gt;&lt;aviation-history&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3865" PostTypeId="2" ParentId="3863" CreationDate="2014-05-13T01:57:51.530" Score="-3" Body="&lt;p&gt;To my knowledge there isn't a coordinate system to describe locations on an aircraft airframe.  Measurements along the longitudinal axis of the aircraft exist for center of gravity measurements.  These measurements are made as an &quot;arm&quot; measurement from a standard arbitrary point, known as the datum.  Specific measurement locations are &quot;stations&quot;.  There is no real need as far as I know to have a measurements in the other 2 axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For locating components for maintenance purposes, my experience of technical manuals usually describe locations verbally, such as &quot;the flap actuator can be located forward of the inboard flap rail&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My experience is mainly with light piston aircraft and corporate jets, it could be different with larger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2337" LastActivityDate="2014-05-13T01:57:51.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3866" PostTypeId="1" CreationDate="2014-05-13T02:17:03.667" Score="4" ViewCount="4249" Body="&lt;p&gt;Starting from being a newly minted private pilot, what are the steps I would have to accomplish in order to eventually qualify for and compete in the Red Bull Air Race? Assuming I put most of my time into the endeavour and progressed at a reasonably fast pace, how long would it take me?&lt;/p&gt;&#xA;" OwnerUserId="2338" LastEditorUserId="247" LastEditDate="2014-05-13T03:30:21.073" LastActivityDate="2014-05-15T20:17:51.807" Title="What does it take to enter the Red Bull Air Race?" Tags="&lt;flight-training&gt;&lt;air-race&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2014-05-18T20:03:36.607" ContentLicense="CC BY-SA 3.0" />
  <row Id="3867" PostTypeId="2" ParentId="3863" CreationDate="2014-05-13T03:11:00.500" Score="13" Body="&lt;p&gt;Stations (STA), generally Fuselage Stations (FS), designate location along the length of the aircraft, increasing from nose to tail. Generally station 0 is somewhere in front of the airplane. One reason for this is that if the airplane grows longer, there still won't be any negative stations, and sections of the plane keep their station numbers. FS 100 can also be placed at an important location (looks like the firewall below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Water lines (WL) designate location in the height of the aircraft, from ground up. You can probably guess by now that these are holdovers from the marine industry. Like the stations, water line 0 is generally a bit below the aircraft, possibly to have WL 100 at the center of the fuselage, or WL 0 could be at the bottom of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Butt lines (BL) designate location left/right on the aircraft, generally centered in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the main system is based on the whole airplane, different parts (like the wings) have their own system of STA, WL, and BL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stations are generally in whatever unit is being used for the aircraft. In the US, this is inches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.techdrawingtools.com/24/l2402.htm&quot; rel=&quot;noreferrer&quot;&gt;this link&lt;/a&gt; for an example and further explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a picture similar to the one below but with more detail, see &lt;a href=&quot;http://3.bp.blogspot.com/-yIua7maWtAY/T6107wJtjVI/AAAAAAAACG0/7lg5XsgnicQ/s1600/F2H-2+Station+Drawing.jpg&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ffGbn.jpg&quot; alt=&quot;Diagram of FS, WL, BL&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-05-13T03:28:51.040" LastActivityDate="2014-05-13T03:28:51.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3868" PostTypeId="1" AcceptedAnswerId="3870" CreationDate="2014-05-13T04:03:51.260" Score="8" ViewCount="11546" Body="&lt;p&gt;How does wind shear affect aircraft while landing and taking off? How do pilots detect that they are encountering wind shear and what would they have to do to prevent it from turning into a bad situation?&lt;/p&gt;&#xA;" OwnerUserId="177" LastEditorUserId="1696" LastEditDate="2015-02-20T20:50:05.817" LastActivityDate="2019-02-18T12:14:38.477" Title="How do pilots detect and respond to windshear while landing and taking off?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;wind&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3869" PostTypeId="2" ParentId="3861" CreationDate="2014-05-13T04:52:21.800" Score="19" Body="&lt;p&gt;On my first cross-country as a student (dual), we actually transitioned through the class B airspace just north of us, flew to a smaller airport north of town, did a landing there, followed by flying back to the class B and landing at the primary airport there before returning home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, I had a few key experiences:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The controllers work quickly and expect you to pay attention.  More than once, as a rather inexperienced pilot, my instructor had to help with the radio, either in understanding the instruction, or helping reduce my confusion by handling communication.&lt;/li&gt;&#xA;&lt;li&gt;Even on a slower Sunday, the center was training a new controller, so there were times the person training had to step in to clear up some of the radio congestion -- we almost had to turn away from the class B, since they hadn't yet assigned us a beacon and cleared us through the bravo.&lt;/li&gt;&#xA;&lt;li&gt;We got vectored around pretty quickly... which, basically threw out all our flight planning (we were expecting this to happen anyway).&lt;/li&gt;&#xA;&lt;li&gt;Talking to approach to land, they told us to expect the visual approach to one of the parallel runways, and the tower controller didn't toss us any curve balls there.  Although, with the headwinds, even with a fair amount of power, we weren't moving very quickly, and probably got cleared to land a bit too early (thankfully, the airspace wasn't busy... but there were a few jets waiting for us to land and taxi off).&lt;/li&gt;&#xA;&lt;li&gt;Ground control and clearance delivery was combined, and they were pleasant enough to give us progressive taxi without asking (I was expecting to write furiously), and also let us taxi to depart off the intersecting runway.&lt;/li&gt;&#xA;&lt;li&gt;Departing after cleared and returning home was pretty uneventful.  At this point, I was out of the way for most traffic.  Much more like being under regular flight following.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Granted, it's not like I was flying into ORD -- it was a pretty slow day at an airport that isn't busy much to begin with -- but I have a feeling if you've been used to flying from a Class C airport, not much will feel different for the most part, especially at one of the smaller Class B airports (and for the bigger ones especially -- DEFINITELY get to know the airport diagram beforehand).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer some of your specific question, the A/FD will list traffic patterns (probably going to be opposing right/left traffic for parallel runways so people don't end up head on at each other) ;) Controllers will guarantee separation from all aircraft, so you'll be assigned a heading and altitude (maybe &quot;at or below&quot;), and possibly a speed.  So really, if your radio communications are good and you're able to fly straight and level, you won't have many problems (it just comes down to obeying clearances, and not violating any airspace).  You're right that you would need an endorsement to fly solo into a Class B airspace, but this would not apply if you were dual with your instructor, since they are PIC.&lt;/p&gt;&#xA;" OwnerUserId="2074" LastActivityDate="2014-05-13T04:52:21.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3870" PostTypeId="2" ParentId="3868" CreationDate="2014-05-13T09:59:47.983" Score="8" Body="&lt;p&gt;The most dangerous form of windshear for planes is the microburst. This is a downdraft that after it hits the ground spreads out in all directions. It is dangerous particularly for planes low to the ground (on takeoff and landing)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a plane coming in for a landing approaches the microburst it will enter a headwind and see and increase of airspeed and lift, the inexperienced and unsuspecting pilot may then reduce engine power to slow down and keep himself aligned. After the plane passes through the burst it will enter a tailwind decreasing lift which may cause the plane to crash into the ground short of the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To prevent crashing the pilot would need to keep power and possibly abort the approach to wait out the burst.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detecting windshear from the ground is done with doppler radars (&lt;a href=&quot;http://en.wikipedia.org/wiki/TDWR&quot; rel=&quot;nofollow noreferrer&quot;&gt;TDWR&lt;/a&gt;) and multiple wind sensors (&lt;a href=&quot;http://en.wikipedia.org/wiki/Low_level_windshear_alert_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;LLWAS&lt;/a&gt;) which can detect the changes in wind which will be relayed to pilots in accordance with &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0301.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;regulations (3-1-8)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol3/pdf/CFR-2012-title14-vol3-sec121-358.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;All turbine powered airplanes used in §121 operations, except for turbopropeller powered airplanes, must have a windshear detection system installed&lt;/a&gt;, this is detected in one of 2 ways, using the onboard weather radar (predictive) or using the wind sensors on the aircraft like the angle of attack and airspeed (reactive).&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="12720" LastEditorDisplayName="user2168" LastEditDate="2017-07-06T21:44:12.923" LastActivityDate="2017-07-06T21:44:12.923" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3871" PostTypeId="1" AcceptedAnswerId="3881" CreationDate="2014-05-13T11:07:49.593" Score="7" ViewCount="20725" Body="&lt;p&gt;I am wondering what is the rule of thumb with correction of the bat?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it 2° for every 5kts?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now i know you can use a E6B.&#xA;But im talking about landing ILS or visuals without bracketing the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So lets say you landing on runway 06 the magnetic heading is 060, the wind is 080/05kts.&#xA;So would the correction be 062?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is a C172&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apologies if this is not a valid question, getting back into aviation&lt;/p&gt;&#xA;" OwnerUserId="2330" LastEditorUserId="1696" LastEditDate="2015-02-20T21:15:32.623" LastActivityDate="2019-02-15T22:46:22.527" Title="What is a general rule for crosswind correction, especially when landing?" Tags="&lt;general-aviation&gt;&lt;crosswind&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3872" PostTypeId="2" ParentId="3871" CreationDate="2014-05-13T11:34:55.320" Score="6" Body="&lt;p&gt;If we set our runway to be aligned to a $x$ axis so the angle is $0°$ and we have an airspeed of $\vec{v_a}$ and a wind of $\vec{v_w}$, this means that ground speed is $\vec{v_g} = \vec{v_a} - \vec{v_w}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We want the $y$ component of $\vec{v_g}$ to be 0 so this means that the $y$ components of $\vec{v_g}$ and $\vec{v_w}$ must cancel each other out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The $y$ component of the wind is our crosswind ($v_c$). To get the $y$ component of our airspeed we take $|\vec{v_a}|\cdot\tan \theta$ where $\theta$ is our heading (0 is parallel to the runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that $|\vec{v_a}|\tan \theta - v_c=0$ or that $\tan \theta = v_c/|\vec{v_a}|$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low crosswind speeds this means that your crab angle in degrees is $\sim 60*\frac{crosswind}{airspeed}$.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorDisplayName="user2168" LastEditDate="2014-05-13T16:30:11.940" LastActivityDate="2014-05-13T16:30:11.940" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3873" PostTypeId="2" ParentId="3866" CreationDate="2014-05-13T14:40:06.220" Score="7" Body="&lt;p&gt;According to their &lt;a href=&quot;http://www.redbullairrace.com/en_GB/article/rules-and-principles&quot; rel=&quot;noreferrer&quot;&gt;about page&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;New pilots who wish to participate in the World Championship must first fulfil the minimum criteria set by the Red Bull Air Race Committee, which include top achievements in international flying competitions organised by the FAI. They must also be active aerobatic air display pilots. Eligible pilots that prove their skills at the Red Bull Air Race Qualification Camp can achieve the Red Bull Air Race Restricted Superlicence. Once they have the Restricted Superlicence, they then qualify to take part in the Red Bull Air Race World Championship in the Challenger Cup.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I would suggest if this is something that interests you, you begin with some instruction in aerobatic flying - a discipline which in itself is quite tough. To find the next qualification camp, I would suggest contacting red bull air race directly. It seems they run annual qualifications, most recently held in Texas, USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of time it would take is impossible to measure, or even speculate. &lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2014-05-13T16:00:07.157" LastActivityDate="2014-05-13T16:00:07.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3875" PostTypeId="2" ParentId="3844" CreationDate="2014-05-13T15:04:54.087" Score="0" Body="&lt;p&gt;On the ground, without airflow over the pitot tube to cool it, it will burn out very quickly. By operating something like this when it's not needed you risk not having it available when you need it.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2014-05-13T15:04:54.087" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3876" PostTypeId="1" AcceptedAnswerId="3879" CreationDate="2014-05-13T15:58:23.093" Score="28" ViewCount="19330" Body="&lt;p&gt;Listening to LiveATC there are references by various ATC entities (towers, approach, etc) to &quot;company&quot;. To what does this refer?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="62" LastEditDate="2014-12-02T18:02:02.747" LastActivityDate="2018-06-25T14:46:22.900" Title="What does ATC mean when they refer to &quot;company&quot;?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3877" PostTypeId="2" ParentId="3876" CreationDate="2014-05-13T16:01:23.960" Score="15" Body="&lt;p&gt;It means, &quot;The same airline as you&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical communication is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Cactus 123: You are cleared to land, 31L. Following Company Traffic on a 2 mile final&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which means:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;You are following another US Airways flight, that is currently 2 miles from the runway&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It helps the pilot identify the airplane out in front of him. For example, if he spots a Red and Blue Southwest plane, he knows he's not looking at the proper plane!  He knows he needs to be looking for another US Air paint scheme.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="11215" LastEditDate="2018-06-25T14:46:22.900" LastActivityDate="2018-06-25T14:46:22.900" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="3878" PostTypeId="2" ParentId="3461" CreationDate="2014-05-13T16:02:55.857" Score="2" Body="&lt;p&gt;I did a quick google search and &lt;a href=&quot;https://www.sounddogs.com/results.asp?Type=1&amp;amp;CategoryID=1005&amp;amp;SubcategoryID=5&quot; rel=&quot;nofollow&quot;&gt;this was a link that I found&lt;/a&gt;.  Although, the quality of these samples leaves a lot to be desired. &lt;/p&gt;&#xA;" OwnerUserId="2179" LastActivityDate="2014-05-13T16:02:55.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3879" PostTypeId="2" ParentId="3876" CreationDate="2014-05-13T16:08:59.093" Score="37" Body="&lt;p&gt;Generally when used in ATC movement instructions the word &quot;company&quot; means &quot;The other aircraft operated by your &lt;em&gt;company&lt;/em&gt;&quot;.&lt;br&gt;&#xA;In this context it's a convenient shorthand for controllers and pilots: If two aircraft from the same operator are going to the same place on the airport (one may be told &quot;Follow company&quot;), or to assist with visual separation and sequencing on approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other cases it can mean &quot;the airline (company) you work for&quot; (such as being instructed to taxi to a ramp and &quot;call company for your gate assignment&quot; - the distinction is made based on the context of the request or instruction).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that this is &lt;em&gt;not standard phraseology&lt;/em&gt;: despite being widely used &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/C.HTM&quot; rel=&quot;noreferrer&quot;&gt;the term &lt;code&gt;company&lt;/code&gt; does not appear in the pilot/controller glossary&lt;/a&gt; or the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Controller's Handbook&lt;/a&gt; .&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2014-12-02T19:22:09.437" LastActivityDate="2014-12-02T19:22:09.437" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="3880" PostTypeId="2" ParentId="3863" CreationDate="2014-05-13T19:20:14.453" Score="5" Body="&lt;p&gt;There is a fair amount of variability between aircraft manufacturers as to how they reference physical locations on their airplanes, especially along the longitudinal axis. Even within a company, different schemes are sometimes used for different models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, on the Boeing 747-100, -200, -300, and -400 aircraft, the reference datum is 90 inches in front of the airplane's nose. Why 90? Because the tip of the 90 inch test probe for pitot tube calibration on the original aircraft was the zero point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for the 767-300 the reference datum is 28.5 inches aft of the airplane nose, which of course means that weight and balance calculations have to deal with negative arms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing uses two systems to refer to a longitudinal axis location. The Boeing Weight and Balance Control and Loading Manual puts it like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Balance Arm (B.A.) A true measure of distance from foward to aft, in inches, from a fixed&#xA;  datum. The fixed datum is selected by the airplane manufacturer.&#xA;  Balance Arms are used in weight and balance calculations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Body Station (B.S.) A manufacturing location on the airplane. For first of an airplane&#xA;  model, B.S. are continuous from the front to the aft of the airplane.&#xA;  For later versions that are either stretched (i.e. fuselage inserts&#xA;  added) or shrunk (i.e. fuselage sections removed), B.S. becomes&#xA;  discontinuous, for manufacturing reasons.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another system for referencing a point along the longitudinal axis is the percent of the mean aerodynamic chord (%MAC), and to the best of my knowledge this is standardized. C.G. limits for the various operating envelopes (zero fuel weight, taxi, takeoff, landing and others) use the %MAC for the x-axis and weight for the y-axis. Thus, weight and balance calculations come up with the actual C.G. in, say, inches, and then translate this to %MAC for to see if the C.G. lies within the the operating envelopes. The calculation is straightforward. Take the C.G. in inches, subtract the leading edge of the MAC, divide by the length of the MAC, and multiply by 100.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that for purposes of C.G. calculation, the wings have to use the same reference system as the fuselage (or have it translatable in reference to the fuselage) because the C.G. of fuel tanks varies depending on how much fuel there is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically wide-body cargo aircraft have lateral imbalance limitations, and for that the lateral referencing system is used. For the 747-400, for example, the maximum lateral imbalance is 10,000,000 inch-pounds up to 846,000 lbs. From there it slopes to 3,340,000 inch-lbs at 913,000 lbs.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-05-13T20:49:14.160" LastActivityDate="2014-05-13T20:49:14.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3881" PostTypeId="2" ParentId="3871" CreationDate="2014-05-13T20:50:15.570" Score="7" Body="&lt;p&gt;What I have learned during my commercial flight training is making use of the speed number.&#xA;Take your TAS, devide it by 60. This is your speed number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now take you XWC (crosswind component).&#xA;Devide the XWC by your speed number. This is the amount of degrees you should crab to stay on track (wind correction angle)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets use an example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are flying in a C172 at 120kts TAS.&#xA;XWC is 18kts from the left. &#xA;120 devided by 60 is 2, so our speed number is 2.&#xA;18kts wind devided by 2 is 9. Now adjust your heading by 9 degrees to the left (into the wind), and you should stay on track. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Worked perfectly fine for me so far.&#xA;Hope it helps! Cheers&lt;/p&gt;&#xA;" OwnerUserId="1051" LastActivityDate="2014-05-13T20:50:15.570" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3882" PostTypeId="5" CreationDate="2014-05-13T20:55:34.943" Score="0" Body="&lt;p&gt;Air racing is a sport that involves airplanes competing over a fixed course, with the winner either returning the shortest time, the one to complete it with the most points, or to come closest to a previously estimated time.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-13T21:17:32.310" LastActivityDate="2014-05-13T21:17:32.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3883" PostTypeId="4" CreationDate="2014-05-13T20:55:34.943" Score="0" Body="Air racing is a sport in which airplanes complete a course in the shortest amount of time." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-13T21:20:40.377" LastActivityDate="2014-05-13T21:20:40.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3884" PostTypeId="5" CreationDate="2014-05-13T20:56:51.047" Score="0" Body="&lt;p&gt;The history of aviation has extended over more than two thousand years from the earliest kites and attempts at tower jumping to supersonic, and hypersonic flight by powered, heavier-than-air jets.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-13T21:21:17.320" LastActivityDate="2014-05-13T21:21:17.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3885" PostTypeId="4" CreationDate="2014-05-13T20:56:51.047" Score="0" Body="Questions about aviation history, starting from kites, balloons, airplanes, helicopters and rockets." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-13T21:20:51.637" LastActivityDate="2014-05-13T21:20:51.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3886" PostTypeId="5" CreationDate="2014-05-13T21:00:33.770" Score="0" Body="&lt;p&gt;More information: &lt;a href=&quot;http://en.wikipedia.org/wiki/Bird_strike&quot; rel=&quot;nofollow&quot;&gt;Bird Strike&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-13T21:21:00.060" LastActivityDate="2014-05-13T21:21:00.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3887" PostTypeId="4" CreationDate="2014-05-13T21:00:33.770" Score="0" Body="For questions about bird strikes and other aviation safety issues related to birds" OwnerUserId="65" LastEditorUserId="62" LastEditDate="2015-01-16T20:29:14.797" LastActivityDate="2015-01-16T20:29:14.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3888" PostTypeId="1" AcceptedAnswerId="3889" CreationDate="2014-05-13T21:11:18.773" Score="14" ViewCount="3377" Body="&lt;p&gt;Would it be possible to float a small plane (say a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_150&quot;&gt;Cessna 150&lt;/a&gt;) off of the deck of an aircraft carrier without the Cessna achieving any forward motion with respect to the aircraft carrier? If not a Cessna 150, is there a standard GA aircraft that could do it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:  Per a comment from ratchet freak: the takeoff would be done via lift from the wings, not via an engine duct (VTOL), like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot;&gt;Harrier&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="13197" LastEditDate="2016-04-24T21:59:34.470" LastActivityDate="2017-04-02T18:24:36.620" Title="Can a small plane be floated off of an aircraft carrier?" Tags="&lt;takeoff&gt;&lt;general-aviation&gt;&lt;aircraft-carrier&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3889" PostTypeId="2" ParentId="3888" CreationDate="2014-05-13T21:28:50.867" Score="20" Body="&lt;p&gt;As far as I'm aware this has never been attempted (and I doubt the Navy would let me try - though I'm certainly game if they are!), but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_J-3_Cub&quot;&gt;Piper J3 Cub&lt;/a&gt; stalls at 38mph (33kts). &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/USS_Enterprise_%28CVN-65%29&quot;&gt;The USS Enterprise (CVN-65)&lt;/a&gt; had a maximum speed of 38.7mph (33.6kts).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, given a lightly loaded cub and an &lt;em&gt;Enterprise&lt;/em&gt;-class carrier at flank speed, it is at least &lt;em&gt;theoretically possible&lt;/em&gt; to float that aircraft off the deck (if it were lightly loaded, and thus had a lower stall speed).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Achieving zero relative motion would require a little more effort - specifically you'd have to seek out a headwind, and the Cub would have to be operating at an airspeed above stall, but still pretty close to it.&lt;br&gt;&#xA;For example, if the Enterprise were making 30 knots and steaming into a 10 knot headwind the relative wind on deck would be 40 knots. That's enough to lift the Cub, but as soon as it was in the air it would need to pull itself along (via its engine) to maintain that speed. The Cub would have zero relative motion above the deck at an airspeed somewhere around 40 knots).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a (slightly ridiculous) bonus: &lt;a href=&quot;http://en.wikipedia.org/wiki/Belite_Aircraft_Superlite&quot;&gt;The Belite Superlite&lt;/a&gt; has a stall speed of 28 mph (25kts). It would be theoretically possible to fly such a plane like a kite from an aircraft carrier. Its &lt;a href=&quot;http://www.beliteaircraft.com/ultralight-aircrafts/specifications.php&quot;&gt;advertised takeoff and landing distances&lt;/a&gt; (both ~500ft) are also such that it could operate from a carrier deck without need for the catapult to launch or arresting wire to stop.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-05-13T21:43:28.830" LastActivityDate="2014-05-13T21:43:28.830" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="3890" PostTypeId="2" ParentId="3888" CreationDate="2014-05-13T21:30:48.270" Score="9" Body="&lt;p&gt;A Cessna 150 can take off at &lt;a href=&quot;http://flighttraining.aopa.org/learntofly/articles/0108.html&quot;&gt;48 knots&lt;/a&gt; rotation speed. An aircraft carrier can do 30 knots, and an 18 knot headwind is certainly possible at sea. That puts a 48 knot wind over the wings, enough for the Cessna to take off. The engine would counteract drag, allowing the plane to &quot;float&quot; off the deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have any doubt about this being possible, just watch what happens if you don't tie down your plane properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=IPOtDPHjW-Y&quot;&gt;http://www.youtube.com/watch?v=IPOtDPHjW-Y&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-05-13T21:54:37.303" LastActivityDate="2014-05-13T21:54:37.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3891" PostTypeId="2" ParentId="3842" CreationDate="2014-05-13T22:25:35.020" Score="7" Body="&lt;p&gt;Generally, to create lift means to deflect the oncoming airstream downwards. How and where this is done in detail on an airplane is less important than doing it with a smooth spanwise lift distribution such that the wake behind the aircraft is trough-shaped.&lt;p&gt;&#xA;A fuselage is disturbing this lift distribution, but not severely. The length of the fuselage means that it creates considerable lift at small incidences, even with the low lift slope of slender bodies. In case of the &lt;a href=&quot;http://en.wikipedia.org/wiki/IPTN_N-250&quot;&gt;N-250&lt;/a&gt; it was found that an incidence of 2° produces the lowest drag. However, this also means that the lift is only just right at one angle of attack, and when the aircraft is flown in different conditions, the fuselage can mess up the lift distribution quite easily, especially if it is wider than necessary.&lt;p&gt;&#xA;During the 1930s and 40s, when this was understood in detail not only in academia, but also in the design offices, progress in engine technology pushed operating altitudes up until planes needed pressurized cabins to transport passengers comfortably. Pressurisation demands a round or nearly-round fuselage cross section to keep structural mass down, so any attempt at widening and shaping the fuselage would result in an unacceptable mass penalty. This ended the experimentation with lift-creating fuselages.&lt;p&gt;&#xA;As for the N-250, the idea of fuselage inclination in cruise is correct in theory, but resulted in massive protests from the cabin crew which now had to push their carts uphill, ending this kind of optimization quickly. This is why it never caught on.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-13T22:25:35.020" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="3892" PostTypeId="2" ParentId="3733" CreationDate="2014-05-13T22:38:56.880" Score="8" Body="&lt;p&gt;To expand a little on this. Some start valves have an override that requires a tool, for example a 3/8 drive ratchet (First picture). While others use a push button to override the normal electrically operated solenoid (Second picture).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0903.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here's an accident report&lt;/a&gt; of what happens when it all goes wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2F81W.png&quot; alt=&quot;767 GE CF6 Engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/evi2L.png&quot; alt=&quot;737-200 JT8D Engine&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-01-10T15:45:19.647" LastActivityDate="2015-01-10T15:45:19.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3893" PostTypeId="2" ParentId="3789" CreationDate="2014-05-13T22:44:45.197" Score="5" Body="&lt;p&gt;There's also the MD-10 upgrade to the DC-10.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The MD-10 program allows operators to retrofit DC-10s with a new,&#xA;  advanced- technology flight deck. Benefits of the retrofit include a&#xA;  two-person flight deck, weight savings, increased reliability, and&#xA;  commonality with the MD-11 fleet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/ps02txt.html&quot; rel=&quot;nofollow&quot;&gt;http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/ps02txt.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just adding a little more info:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FAA Certifies New B757/767 Aftermarket Flight Deck&#xA;  Dreamliner-Inspired Large-Format Display System Enhances Situational Awareness&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aero-news.net/index.cfm?do=main.textpost&amp;amp;id=c3201f75-7587-4438-a2b8-e35c3cb34759&quot; rel=&quot;nofollow&quot;&gt;http://www.aero-news.net/index.cfm?do=main.textpost&amp;amp;id=c3201f75-7587-4438-a2b8-e35c3cb34759&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1961" LastEditDate="2014-07-20T12:18:33.510" LastActivityDate="2014-07-20T12:18:33.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3894" PostTypeId="1" AcceptedAnswerId="3898" CreationDate="2014-05-14T01:56:43.103" Score="5" ViewCount="7188" Body="&lt;p&gt;Earlier today, a friend asked me what this symbol (referring to an airport in Canada) on a weather depiction chart represented.  I didn't know. (Full chart available &lt;a href=&quot;https://i.stack.imgur.com/LzB5y.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jnM8j.png&quot; alt=&quot;Dot inside parenthesis on a weather depiction chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What does a dot inside parenthesis mean on a weather depiction chart?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-05-14T06:32:25.257" LastActivityDate="2014-05-14T06:34:56.433" Title="What does a dot inside two parenthesis mean on a weather depiction chart?" Tags="&lt;weather&gt;&lt;symbology&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3896" PostTypeId="2" ParentId="3461" CreationDate="2014-05-14T03:20:57.903" Score="3" Body="&lt;p&gt;One place to look is models of the planes for flight simulators. There is generally a &quot;sounds&quot; folder of some sort inside the airplane folder that includes some cockpit sounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing the original files are proprietary and there is really no reason for the companies to freely share them. Shows like Air Crash Investigation might get access to a simulator that can make all the real sounds.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-14T03:20:57.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3897" PostTypeId="2" ParentId="3868" CreationDate="2014-05-14T03:49:45.087" Score="4" Body="&lt;p&gt;Windshear recognition and recovery, both during takeoff and landing are regularly practiced in simulators. Recognition includes a sudden loss of airspeed or a sudden increase in airspeed (probably to be followed by a sudden loss). Recovery (at least back when I was flying) included going to max power while bringing the nose up until stick shaker activation, which condition you would fly in until through the shear. &lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2017-07-06T23:47:41.667" LastActivityDate="2017-07-06T23:47:41.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3898" PostTypeId="2" ParentId="3894" CreationDate="2014-05-14T05:14:07.740" Score="7" Body="&lt;p&gt;From &lt;a href=&quot;http://www.msrc.sunysb.edu/~chang/atm247/Ch2_figures/weather_symbols_2.jpg&quot;&gt;here&lt;/a&gt;, $(\cdot)$ means that there is precipitation within sight, reaching the ground, not at the station, but &amp;lt; 5 km from the station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$)\cdot($ means that there is precipitation within sight, reaching the ground, not at the station, but &gt; 5km from the station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sussex.ac.uk/weatherstation/technical/symbols/symbol.html&quot;&gt;This source&lt;/a&gt; and &lt;a href=&quot;http://www.atmo.arizona.edu/students/courselinks/spring12/atmo170a1s2/lecture_notes/station_model/sta_model_handout_p01.jpg&quot;&gt;this source&lt;/a&gt; give similar definitions, but without a strict distance cutoff, instead just saying &quot;distant&quot; and &quot;near&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find any references to this symbol in &lt;a href=&quot;https://flightplanning.navcanada.ca/cgi-bin/CreePage.pl?Langue=anglais&amp;amp;NoSession=NS_Inconnu&amp;amp;Page=wxsymbols&amp;amp;TypeDoc=wxsymb&quot;&gt;Nav Canada's weather code and symbol legend&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorDisplayName="user2168" LastEditDate="2014-05-14T05:32:59.517" LastActivityDate="2014-05-14T05:32:59.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3899" PostTypeId="1" AcceptedAnswerId="3921" CreationDate="2014-05-14T07:29:07.930" Score="21" ViewCount="17782" Body="&lt;p&gt;So I was at an air show and saw a C-130J Super Hercules showcasing its capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The take-off distance it covered was amazingly short (I guess equal to fighter jets), even though it uses propeller based engines. The landing was also super short.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How does such a massive plane manage to take off in short distances ? Is it because it has four engines?&lt;/li&gt;&#xA;&lt;li&gt;During landing, I couldn't see any thrust reverser (as in commercial jets) in play. What tech does it use to stop so quickly?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2344" LastEditorUserId="15311" LastEditDate="2017-12-05T19:27:01.030" LastActivityDate="2018-08-30T23:18:32.717" Title="How does a large cargo plane like the C-130 Hercules take off and land in such a short distance?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;takeoff&gt;&lt;c-130&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3900" PostTypeId="2" ParentId="3899" CreationDate="2014-05-14T07:57:51.973" Score="8" Body="&lt;p&gt;the props are turbo props (more specifically &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_AE_2100&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Rolls-Royce AE 2100&lt;/a&gt; with 4.6k shaft horsepower) and very efficient propeller blades. This combines into a takeoff distance of 953 m at 70 ton, and at the air show they would have kept the plane nearer the empty weight (which is half that) which shortens the needed takeoff length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To compare the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed C-130 Hercules&lt;/a&gt; has a slightly longer takeoff distance at the same weight but only needs half that when the weight is reduced to 36 ton.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These propeller blades can change their pitch which can reverse the thrust direction, plus the wheel brakes (even large jets use mostly wheel brakes see &lt;a href=&quot;https://aviation.stackexchange.com/a/1220/609&quot;&gt;this answer&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-05-14T08:11:46.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3902" PostTypeId="1" AcceptedAnswerId="3904" CreationDate="2014-05-14T10:27:43.427" Score="6" ViewCount="5494" Body="&lt;p&gt;Why do people have to worry about CG? Is it primarily due to fuel penalty, or take-off and landing performance, or is it mostly just to keep the aircraft from tipping over during loading and unloading, or other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bonus, does tipping over of aircraft actually occur these days due to improperly managed CG?&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="3386" LastEditDate="2016-10-11T17:02:14.303" LastActivityDate="2016-10-11T17:02:14.303" Title="Why is managing CG (centre of gravity) important?" Tags="&lt;aircraft-performance&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3903" PostTypeId="2" ParentId="3888" CreationDate="2014-05-14T10:51:59.497" Score="5" Body="&lt;p&gt;What you say is not only possible, but it has been used to land a plane on a much smaller (and a bit faster) ship than an aircraft carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try to search in the web for the video &quot;Extreme small plane landing on a ship at sea&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a working link at the moment: &lt;a href=&quot;http://www.youtube.com/watch?v=pUdzVnZBaoY&quot; rel=&quot;noreferrer&quot;&gt;http://www.youtube.com/watch?v=pUdzVnZBaoY&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2345" LastActivityDate="2014-05-14T10:51:59.497" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3904" PostTypeId="2" ParentId="3902" CreationDate="2014-05-14T11:26:39.413" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why do people have to worry about CG?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because the manufacturer has designed the aircraft following certain criteria, and one of those is where the CG will be during flight. If the CG is outside that interval, the elevator will not have enough autority to keep level flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;does tipping over of aircraft actually occur these days due to improperly managed CG?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Was not improperly &quot;managed&quot;, but it went out of bounds (in particular, the aft limit), unfortunately, soon after take-off and &lt;a href=&quot;https://www.youtube.com/watch?v=7sUWC2jfjqI&quot;&gt;a 747 with 7 people on board was lost&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-05-14T11:26:39.413" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="3905" PostTypeId="1" AcceptedAnswerId="3908" CreationDate="2014-05-14T12:22:01.040" Score="18" ViewCount="4301" Body="&lt;p&gt;I am curious about the redundancy they provide in modern era commercial aircraft. &#xA;Here are the questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If an aircraft suffers partial or complete software malfunction, do the pilots have the choice of flying the craft with help of analog consoles for critical systems(e.g. speed, altitude, heading indicators and basic flight controls). It summarizes to the point whether they provide such analog devices ? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of such failure, can the engines keep running so as to provide thrust, fuselage pressurization and breathable air supply to cabin?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2344" LastEditorUserId="946" LastEditDate="2014-05-15T17:29:56.120" LastActivityDate="2015-06-19T10:27:57.187" Title="Are modern aircraft provided with analog consoles in case of a software failure?" Tags="&lt;flight-instruments&gt;&lt;software&gt;&lt;aircraft-failure&gt;&lt;engine-failure&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3907" PostTypeId="2" ParentId="3857" CreationDate="2014-05-14T12:59:10.243" Score="1" Body="&lt;p&gt;From what i understand yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They land on waterways&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kml0f.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2330" LastActivityDate="2014-05-14T12:59:10.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3908" PostTypeId="2" ParentId="3905" CreationDate="2014-05-14T13:12:46.783" Score="24" Body="&lt;p&gt;All commercial aircraft have some form of redundancy in their instrumentation, but it's not always in the form of &quot;analog&quot; instruments. The backup is often electronic itself. But the overall system is designed with a very high level of redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical modern jet aircraft has an &lt;a href=&quot;http://en.wikipedia.org/wiki/Electronic_flight_instrument_system&quot;&gt;Electronic Flight Instrument System&lt;/a&gt; (EFIS), which is the large screen Primary Flight Display (PFD) you see in front of both pilots. There are usually also one or more Multifunction Displays (MFDs) in the middle between the pilots. These displays form the primary instrumentation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EFIS itself is designed with a very high level of redundancy between the pilot's and copilot's side displays. Both are on independent electrical circuits and receive information from independent input computers (&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_data_computers&quot;&gt;air-data&lt;/a&gt; [ADC], &lt;a href=&quot;http://en.wikipedia.org/wiki/Attitude_and_heading_reference_system&quot;&gt;attitude/heading&lt;/a&gt; [AHRS], etc.). Both can usually also be switched over to the other set of input computers. Usually, the MFD can also be configured in a &quot;reversionary&quot; mode where it looks and acts like a PFD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the entire EFIS system should fail, there is also a backup set of instruments. In modern times this backup is usually one or two &lt;a href=&quot;http://en.wikipedia.org/wiki/Integrated_standby_instrument_system&quot;&gt;Electronic Standby Instrument Systems&lt;/a&gt; (ESIS). These are essentially smaller, condensed &quot;PFDs&quot; that display critical information. They usually either contain their own miniature AHRS/ADCs or are connected to isolated computers. They are also powered on a totally independent electrical circuit and often have their own dedicated battery as well, separate from the main aircraft battery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern engines are controlled by completely different computers called &lt;a href=&quot;http://en.wikipedia.org/wiki/FADEC&quot;&gt;Full-Authority Digital Engine Controllers&lt;/a&gt; or FADECs. Two or more FADEC channels are provided for each engine, so that if either channel fails, the other can take over. FADECs are also considered flight-critical items, and are designed with fail-passive capability: even if both FADEC channels fail, the engines can still run and be controlled more primitively and less efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electronic pressurization controllers don't always have redundant computer modules, but a manual pressurization control mode is always provided. In the worst case, the pilot has the ability to manually open or close the cabin outflow valve to control cabin pressure. And redundant pressurized air sources are available from each engine.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="64" LastEditDate="2014-05-14T16:12:48.257" LastActivityDate="2014-05-14T16:12:48.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3909" PostTypeId="2" ParentId="777" CreationDate="2014-05-14T13:56:53.603" Score="10" Body="&lt;p&gt;There are probably several major effects. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Piloting is a &quot;bikini inspector&quot; job, one that people will do because they enjoy it and the social status it may convey. If you have a passion for a profession, you will work in it for less. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After all, people pay to pilot planes as a sport, so some percentage of pilots will work for relatively little pay just so they can fly. Those people making sub-optimum strictly economic decisions, pull down salaries in the field. You see that in other fields as well, such as Chefs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Deregulation and globalization: From the early 1950s through the mid-1980s, airlines were run as government monopolies with government price fixing and protection from competition. Flying was a relatively high-margin business that catered to those flying on corporate money or who were individually wealthy (&quot;the jet set.&quot;) People who chauffeur the rich tend to be better compensated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deregulation and opening of air travel to international markets drove down all costa as customers sought the best value. It has happened in every deregulated industry. Back when AT&amp;amp;T was a national government corporate monopoly, everyone, even down to the janitors, got above-market wages, unionized or not. After the monopoly broke up, wages went down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the past, airlines were semi-militarized and I know for some period back in the 50s and 60s, you had to be a US citizen to pilot commercial aircraft in the US. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) As a field matures, its wages drop. Most technologies have a sideways-s growth curb where they start slow, have two to three decades of explosive growth and then plateau off. In the growth era, wages are high and then they regress relative to the general wage. In cars, it was 1920s-1960s; in computers, it was 1980s-now; in aviation, the explosive growth was 1930s-1970s.  (WWII threw things off some.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) People who can be pilots are not as relatively rare as they used to be. My grandfather was a mail pilot in the 1930s and WWII. Pilots back then had to be physically strong, immune to fatigue and able to do a lot of math on the fly (so to speak.) They were very extraordinary people and were often paid accordingly (e.g. clipper plane pilots made ridiculous amounts of money in the 1930s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As planes gained larger crews and have become progressively automated, the potential talent pool in the general population has expanded. It's not just that more people can become pilots, it's that existing pilots can fly longer. In the 1950s, you didn't see 60 year old pilots. Now you do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's easier to become a pilot these days. When I was in my teens circa 1980, I wanted to get a civil aviation license, but couldn't because I was blind in one eye. Today, I can. An expanded talent pool decreases prices. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;5) Pilots and aircrew in general are not as key as they once were. Now they are part of a larger team, many of whom stay on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also speculate that pilots just aren't as skilled, relative to the rest of the population, as they used to be. It's not just that the job is more automated and team driven, but that other jobs have reason to and have surpassed the technical complexity of piloting. Compared to other professions out there now, pilots are not the elites they once were. Their pay has regressed accordingly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a &quot;pilot&quot; shortage, its likely that 1) airlines can't find pilots of a certain rating or pilots who can fulfill some regulation of training or flight time or 2) the margins in the industry are so slim that the industry has a very narrow compensation window. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect its the latter. Flying is commodity now. People fly like they used to take the bus 30+ years ago. If you're working the same economic niche as a bus driver, well, you will get paid like one. &lt;/p&gt;&#xA;" OwnerUserId="2300" LastEditorUserId="2171" LastEditDate="2014-05-14T16:01:13.723" LastActivityDate="2014-05-14T16:01:13.723" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3911" PostTypeId="5" CreationDate="2014-05-14T14:54:47.453" Score="0" Body="&lt;p&gt;The &lt;em&gt;rudder&lt;/em&gt; of an aircraft is one of the aircraft's &lt;a href=&quot;/questions/tagged/control-surfaces&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;control-surfaces&amp;#39;&quot; rel=&quot;tag&quot;&gt;control-surfaces&lt;/a&gt;; usually mounted on the trailing edge of the &lt;a href=&quot;/questions/tagged/vertical-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vertical-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;vertical-stabilizer&lt;/a&gt;, it enables the aircraft to yaw (turn about the axis passing vertically [in the aircraft's frame of reference] through the aircraft's center of gravity) to the left or right relative to the airflow around the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rudder is used very little during normal flight, unlike the &lt;a href=&quot;/questions/tagged/elevator&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;elevator&amp;#39;&quot; rel=&quot;tag&quot;&gt;elevator&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/ailerons&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ailerons&amp;#39;&quot; rel=&quot;tag&quot;&gt;ailerons&lt;/a&gt;.  There are three main situations in which significant rudder inputs are used, all of them during less-than-perfect circumstances:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When landing an aircraft in a crosswind, the rudder is deflected into the wind to allow the aircraft to line up its longitudinal axis with that of the runway without being blown sideways by the wind; for instance, if the wind is blowing across the runway from left to right, the rudder is deflected to the left to compensate.&lt;/li&gt;&#xA;&lt;li&gt;If a multiengine aircraft suffers a failure of an engine located off-center, this produces a thrust imbalance that will tend to yaw the aircraft towards the side with the failed engine.  Deflecting the rudder to the side opposite the failed engine counteracts this and allows the aircraft to fly straight despite the asymmetry in thrust; for instance, if an engine mounted on the left wing fails, the rudder is deflected to the right to compensate.&lt;/li&gt;&#xA;&lt;li&gt;When the aircraft is on the ground, it cannot turn itself by banking, as the ground would get in the way.  Therefore, the rudder is used if the aircraft has to turn while moving at high speed during ground operations; for instance, if an aircraft on its takeoff run has to dodge an obstruction on the runway that either wasn't there or wasn't visible when it began taking off, or if one of an aircraft's wheel bogies collapses during a landing and causes the aircraft to veer to one side.  (&lt;em&gt;Low&lt;/em&gt;-speed turns are instead accomplished by steering the aircraft's nosewheel/tailwheel, and/or by differential &lt;a href=&quot;/questions/tagged/braking&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;braking&amp;#39;&quot; rel=&quot;tag&quot;&gt;braking&lt;/a&gt;.)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rudder#Aircraft_rudders&quot; rel=&quot;nofollow noreferrer&quot;&gt;See Wikipedia&lt;/a&gt; for more information.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-07-28T04:22:43.423" LastActivityDate="2019-07-28T04:22:43.423" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3912" PostTypeId="4" CreationDate="2014-05-14T14:54:47.453" Score="0" Body="A directional control surface, usually mounted on an aircraft's vertical stabilizer, which causes an airplane to yaw (and, sometimes, roll) to the left or right when deflected." OwnerUserId="65" LastEditorUserId="22726" LastEditDate="2019-04-04T07:44:52.097" LastActivityDate="2019-04-04T07:44:52.097" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="3913" PostTypeId="5" CreationDate="2014-05-14T14:56:00.103" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-05-14T14:56:00.103" LastActivityDate="2014-05-14T14:56:00.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3914" PostTypeId="4" CreationDate="2014-05-14T14:56:00.103" Score="0" Body="The Cessna Aircraft Company is an American general aviation aircraft manufacturing corporation headquartered in Wichita, Kansas. Best known for small, piston-powered aircraft, Cessna also produces business jets. The company is a subsidiary of the U.S. conglomerate Textron." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-14T16:06:49.607" LastActivityDate="2014-05-14T16:06:49.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3915" PostTypeId="1" AcceptedAnswerId="3918" CreationDate="2014-05-14T15:03:05.863" Score="12" ViewCount="38632" Body="&lt;p&gt;I'm halfway through a 10-year plan to pay for pilot training and buy my own plane (or a share of one).  When I was introduced to flying by a friend, he said if he had the chance to do it over again, he would have saved up and bought a plane before he started instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefits he mentioned:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Learn in the plane you'll be flying.&lt;/li&gt;&#xA;&lt;li&gt;Avoid &quot;throwing away&quot; rent money.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What I've seen in most cases, though, is that most people get their license before getting a plane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus my question: when does it make sense to buy a plane before training for your PPL?&lt;/p&gt;&#xA;" OwnerUserId="21" LastActivityDate="2018-08-29T21:13:40.503" Title="In what cases does it make sense to buy a plane before you begin pilot training?" Tags="&lt;flight-training&gt;&lt;aircraft-ownership&gt;" AnswerCount="6" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3916" PostTypeId="2" ParentId="3915" CreationDate="2014-05-14T15:49:35.507" Score="7" Body="&lt;p&gt;There are two assumptions in your questions which could be addressed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, learning in the plane you'll be flying: it might also be useful to learn to adapt to different planes. Each plane is a bit different to control and not everything on the plane is standard across manufacturers. You might be better off starting to learn how to adapt your flying to the machine instead of locking yourself into a particular model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, rent money isn't really &quot;thrown away&quot;. You're paying for the convenience of not owning which is to not have to think about issues like maintenance for example. Let's you focus on the joys of flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, it makes sense to buy a plane before learning how to fly if:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you're 100% committed to flying&lt;/li&gt;&#xA;&lt;li&gt;you worked out &lt;em&gt;all&lt;/em&gt; the costs (money, time, your energy, etc.)&lt;/li&gt;&#xA;&lt;li&gt;you're able to go up the learning curve of how to fly + be an owner at the same time&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, it's worth remembering that an airplane is an asset that depreciates over time.&lt;/p&gt;&#xA;" OwnerUserId="1868" LastActivityDate="2014-05-14T15:49:35.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3917" PostTypeId="2" ParentId="3915" CreationDate="2014-05-14T15:55:30.823" Score="7" Body="&lt;p&gt;If I were you I'd only buy an airplane once I'd successfully got my license and flown enough to know what you want to own long-term. Once you know more about it you can make an informed decision. Also, you will be able to judge whether an airplane is worth buying, or whether you'll be inheriting a load of expensive problems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Owning an airplane is very expensive, with a lot of up-front costs. It only makes sense over renting if you fly a lot, and even then over time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By all means start saving, but wait. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-05-14T15:55:30.823" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3918" PostTypeId="2" ParentId="3915" CreationDate="2014-05-14T17:17:54.153" Score="11" Body="&lt;p&gt;I will mention some considerations that were not mentioned above. First of all, it does make sense to buy a plane for training, and it can save you a lot of money on rent but you need to be aware of what you are doing. The positive side is that airplanes do not depreciate as fast as most assets of their kind (it is not unheard of being able to sell an airplane for practically the same amount as you bought it several years ago). However, consider that:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Usually an airplane you want to train in (something sturdy and easy to control, like a C-150) is not an airplane you would like to fly most of the time (traveling in a 150 is not a lot of fun, now a twin Comanche is a different story...).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Insurance costs for a student pilot (even with various restrictions) can nearly negate the advantage of not having to rent.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So, if you would like to buy an airplane to &lt;em&gt;mostly&lt;/em&gt; train (and have some fun occasionally) and then sell and buy a 'travel' (or aerobatic) airplane, it can save you money. It is better to get your private first, however, so you can concentrate on initial training (which is a handful) without worrying about the 'pleasures' of plane ownership.&lt;/p&gt;&#xA;" OwnerUserId="1343" LastEditorUserId="65" LastEditDate="2014-05-14T17:32:49.567" LastActivityDate="2014-05-14T17:32:49.567" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="3919" PostTypeId="2" ParentId="3306" CreationDate="2014-05-14T18:48:16.143" Score="17" Body="&lt;p&gt;Having been reading up on 1930s and 1940s aircraft, I can think of a few major problems that dogged the design back then. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pushers had advantages of pushing the wings and control surfaces through undisrupted air and that gave enough advantages that the a lot of pusher designs were put forward. A pusher would have superior cruising speed and better wing loading because it flew through undisturbed air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most successful was probably the &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_XB-42_Mixmaster&quot;&gt;XB-42 mixmaster&lt;/a&gt; which would have been deployed had the war gone on. (As it was, it it eventually deployed as America's first jet bomber.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-36 used pushers precisely to give its wings a clear airflow. It was actually designed in 1942. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But they had big tradeoffs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A major problem with pusher designs of that era was cooling the engine on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a tractor (puller) you have this giant fan running blowing air over the plane and the engine (air cooled radial) and/or radiator (water cooled.) With a pusher, the prop just blew air behind the plane, leaving a powerful engine with nothing but passive cooling. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a crash, a tractor engine in front served as a crumple zone for the rest of the plane, particularly the cockpit and could plow through obstacles making the plane come to a halt slower. Conversely, with a pusher, the engine was behind the pilot and not only didn't offer any protection but tended to tear loose and ram through the rest of the fuselage like a pile driver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot could not see and therefore visually inspected the engine e.g. if you start loosing oil in a tractor, you know right away. If the engine is behind you, you might not notice until you see the gauge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Center of thrust was more difficult to balance and that made center of gravity tricky as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still, with all these disadvantages, XB-42 and B-36 showed that the advantages could be come out on top with enough good engineering. And in the end, jets work at least half by pushing. If jets had be delayed a few years or the war had started back in the mid-30s, we probably would have seen more pusher designs in service. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With jets, the military need for pushers disappeared and in civilian aircraft, there is seldom much need for an increase in performance that justifies fighting all the tradeoffs. &lt;/p&gt;&#xA;" OwnerUserId="2300" LastActivityDate="2014-05-14T18:48:16.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3920" PostTypeId="2" ParentId="3905" CreationDate="2014-05-14T20:31:34.443" Score="8" Body="&lt;p&gt;Surprisingly, whilst most combat aircraft are jam packed with fall back analog instrumentation, despite often being aerodynamically unstable and requiring fly by wire to actually fly (SU-27 for example), many modern airliners do not even though they are actually stable and can be flown manually (Go figure!). They do however, have multiple resilient systems as stated by dvnrrs above, and importantly, pilots use (Or should use) a &quot;cross-check&quot; in the event of instrument failure. So, if for example IAS is lost, then ground speed, engines, pitch, etc. should be used instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This subject has been discussed in depth, and with massively serious consequences since the French Airbus disaster Flight 447. Reports of flight 447 show that airspeed information was lost as one of the critical factors leading up to the accident. Increased pilot training and systems will be coming I think to help mitigate future failings like occurred on that tragic day over the Atlantic ocean.&lt;/p&gt;&#xA;" OwnerUserId="2350" LastActivityDate="2014-05-14T20:31:34.443" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3921" PostTypeId="2" ParentId="3899" CreationDate="2014-05-14T21:11:34.543" Score="17" Body="&lt;p&gt;Takeoff and landing distance have a lot of variables.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One is certainly thrust. The plane is designed such that it has enough thrust to reach takeoff speed within the available takeoff distance. For landing, the propellers are able to reverse the thrust and add extra braking power to stop in a shorter distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another variable is landing and takeoff speed. If you lower takeoff and landing speeds, it takes less distance to get going and to stop. Being a propeller plane with a straight (non-swept) wing, it is designed to fly slower than jet aircraft. This means the plane needs less angle of attack to fly at slower speeds. The C-130 also has very large flaps for this purpose, and they contribute to lowering takeoff and landing airspeeds in two ways. First, the flaps are very large, which adds more wing area and also deflects more air downwards, increasing lift. Second, the flaps are placed directly behind the engines, which allows the flaps to direct some of the engine thrust downwards, further increasing lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weight is also important. While the C-130 is designed for good performance at 155,000 lb, and can fly at up to 175,000 lb, it will be much lighter in a demonstration. From an empty weight of 75,562 lb, fuel and crew will still leave it well below its typical operating weights. The lower weight means that takeoff performance will be increased by better acceleration and a lower liftoff speed. Landing performance will also be better with a lower landing speed and better deceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The newer &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_C-130J_Super_Hercules#Specifications_.28C-130J.29&quot; rel=&quot;noreferrer&quot;&gt;C-130J&lt;/a&gt; also performs better than the older &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-130_Hercules#Specifications_.28C-130H.29&quot; rel=&quot;noreferrer&quot;&gt;C-130H&lt;/a&gt;. The newer engines on the J model produce up to 4,637 shaft horsepower (shp) each (though they are listed &lt;a href=&quot;https://www.caa.co.uk/docs/1419/SRG_PRO_Ptcds116iss7.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; at 4,705 shp), while the engines on the H model produce up to 4,590 shp each. The empty weight on the J model is 75,562 lb and on the H model is 75,800 lb. So with the empty weight going down by 238 lb and the power increasing by at least 47 shp, and improved propellers, the J model has better performance. The takeoff distance at 155,000 lb is 3,127 feet for the J model versus 3,586 feet for the H model. The H model can take off in 1,400 feet at 80,000 lb (probably closer to the weight in demonstrations), so the J model can probably do even better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/x2dLk.jpg&quot; alt=&quot;C-130 with flaps down&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-02T19:59:07.973" LastActivityDate="2014-12-02T19:59:07.973" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3922" PostTypeId="1" AcceptedAnswerId="3924" CreationDate="2014-05-15T02:40:00.247" Score="4" ViewCount="409" Body="&lt;p&gt;When needing to deviate due to weather, does asking for deviation &quot;due to weather&quot; give ATC any leeway in terms of aircraft separation? &lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="572" LastEditDate="2015-02-19T09:37:27.867" LastActivityDate="2015-02-19T09:37:27.867" Title="Does asking for deviation due to weather give ATC any leeway for reducing separation between aircraft?" Tags="&lt;air-traffic-control&gt;&lt;weather&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3924" PostTypeId="2" ParentId="3922" CreationDate="2014-05-15T07:09:34.970" Score="7" Body="&lt;p&gt;No, it does not. ATC can specify a restriction to the deviation, especially in a non-radar environment where they can't keep an eye on you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing that frees ATC of separation responsibilities between two IFR (or IFR/VFR depending on airspace) aircraft is if one them reports the other in sight, and is issued an &quot;maintain visual separation&quot;. After that the responsibility of not hitting the other aircraft, or its wake, rests solely with the pilot in command.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-05-15T14:30:08.243" LastActivityDate="2014-05-15T14:30:08.243" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="3925" PostTypeId="2" ParentId="3685" CreationDate="2014-05-15T09:58:28.017" Score="7" Body="&lt;p&gt;This answer was difficult to find as both Flight Operation Manuals and Maintenance Manuals did not say. The only guidance was found in the system description provided by the OEM of the BCSU.  I am not mentioning the fleet type because at some point the detailed description might become proprietary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the description I found for a given automatic braking system is that it is &lt;strong&gt;armed&lt;/strong&gt; when the pilot presses one of the three pushbutton switches which set the auto-brake level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system will only arm if gear up is not commanded, there is hydraulic pressure as needed, and no existing faults exist that prohibit normal braking, as well as a few other computers available on the associated data bus. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is nothing that says the system can't be armed after touchdown, however the system will only engage when the spoilers are being activated, or are activated. Or more precisely from the black-box point of view &lt;strong&gt;automatic braking is engaged&lt;/strong&gt; whenever two spoiler signals in three appear once automatic braking has been armed.  In other words, once armed, the automatic braking will only engage if spoilers are sending the signal that they are being activated, or are activated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It specifically says that &lt;strong&gt;the pilot can select another pushbutton switch even after&#xA;arming.&lt;/strong&gt; The BSCU acknowledges this new command and executes&#xA;the corresponding task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automatic braking is released whenever the braking sequence&#xA;is interrupted:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;when an arming condition disappears,&lt;/li&gt;&#xA;&lt;li&gt;when an engaging condition disappears,&lt;/li&gt;&#xA;&lt;li&gt;when one or both brake pedals are held down beyond the&#xA;defined threshold,&lt;/li&gt;&#xA;&lt;li&gt;when the selected pushbutton is pressed again.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The question, therefore is 'After you have already armed at a given setting and the system is actually engaged, because the spoiler actuation has initiated auto-braking, what happens when you press another setting?'  &lt;strong&gt;As long as the arming conditions still exist, which in most cases would, and as long as the engage conditions exist, as would be the case if the spoilers are activated (at least 2 of three spoiler signals being sent to the BSCU), then yes, you may change the setting after touchdown and the BSCU acknowledges this new command and executes the corresponding task.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="2213" LastEditDate="2014-05-15T10:13:05.333" LastActivityDate="2014-05-15T10:13:05.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="3926" PostTypeId="2" ParentId="3888" CreationDate="2014-05-15T17:47:02.470" Score="3" Body="&lt;p&gt;It all depends on the minimum flight speed and the ship's maximum speed. Even with the slow speed of submarines, floating a flying machine is possible if the machine has been designed that way.&lt;p&gt;&#xA;In order to increase the observation radius of submarines (typically only 5nm), an unpowered gyrocopter was designed in 1941 to lift an observer 500 ft up into the air to increase the observation radius to 25 nm. Gyrocopters are known for their low flying speeds, and this one, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Focke-Achgelis_Fa_330&quot; rel=&quot;nofollow&quot;&gt;Focke-Achgelis 330&lt;/a&gt;, was designed to be folded away in a watertight container and to be stored on the deck of the submarine. It could be assembled and de-assembled within 20 minutes and was then towed behind the submarine like a kite. The minimum flight speed was only 27 km/h (14.5 its), just enough for a submarine going at full speed and a little wind.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-15T17:47:02.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3927" PostTypeId="2" ParentId="3902" CreationDate="2014-05-15T18:03:51.707" Score="14" Body="&lt;p&gt;To balance the aircraft, the sum of the lift from all lifting surfaces has to be at the same position as the weight. If the c.g. is ahead of the center of lift, the aircraft will pitch down. The pilot can counteract this by pulling on the elevator, which in effect reduces lift at the tail and thus shifts the center of lift forward. As you can imagine, there is only so much lengthwise change which can be effected with the elevator. So the first limit for the c.g. position is given by controllability.&lt;p&gt;&#xA;Another important consideration is stability. You want the airplane to return to the original flight attitude if it has been disturbed, say by jolt on the stick or yoke. This can be done by creating proportionally more lift with the forward surfaces (= the wing in a conventional configuration) than with the tail surfaces. Say the jolt pitches the aircraft up. Now the aerodynamic forces should change in a way which increases lift proportionally more on the tail surfaces, so the aircraft pitches down and returns to it's original attitude. By distributing lift the way I mentioned above, the same change in angle of attack on both wing and tail will create a proportionally higher lift increase on the tail, making the aircraft (statically) stable. Thus, the second important limit for c.g. location is stability.&lt;p&gt;&#xA;As for tipping over …&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qadEL.jpg&quot; alt=&quot;Two pictures with tipped-over donkey cart and DC-10&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:18:14.040" LastActivityDate="2015-05-07T06:18:14.040" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="3928" PostTypeId="2" ParentId="3370" CreationDate="2014-05-15T19:56:38.163" Score="2" Body="&lt;p&gt;There are so many standards regulating the inspection and maintenance of aircraft, that when a plane is legally in the air, it is most probably safe enough to be there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airline operators, efficiency is at the order of the day. You will thus find that even if some 'old' airliners are still being operated, they are very different from the day they first entered into service. The engines are probably much newer and much more efficient models and avionics is also always replaced with the latest affordable technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Old planes evoke nostalgia and are very fun to fly for leisure. Due to all the regulating standards it is great that some of these old planes can still be flown.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2014-05-15T19:56:38.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3930" PostTypeId="2" ParentId="3370" CreationDate="2014-05-15T21:32:37.283" Score="8" Body="&lt;p&gt;The answers so far give many valid reasons, but two more are missing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In GA aircraft, progress has stopped in airframe design somewhere in the Sixties. Only the home build community has really improved the designs, and the avionics have tremendously improved, but commercial GA aircraft have still the same structure and engines. Since the number of active pilots has dropped, the number of old airplanes makes new designs (again, outside of the home build area) commercially questionable, and their performance would be comparable to the ones from 50 years ago.&lt;/li&gt;&#xA;&lt;li&gt;Grandfather rules: The rules which have been in force at the time the aircraft was built are still valid for that particular aircraft, which makes compliance much easier than with newly built aircraft. All certification authorities all over the world have only added to the body of regulations in the last decades. If you think of it, this makes sense (for them): There is no incentive to remove old and by now superfluous rules, and new rules are issued if only to show that the bureaucracy is active and needed.&#xA;&lt;p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Whenever I read some old aircraft magazine from the Fifties or Sixties, I find the ads most striking for showing modern-looking planes alongside really outdated automobiles. The aircraft development in General Aviation has stopped a long time ago, whereas the car industry still needs to entice it's customers with regular updates.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-15T21:32:37.283" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="3931" PostTypeId="1" CreationDate="2014-05-15T22:59:12.277" Score="1" ViewCount="1071" Body="&lt;p&gt;I have a question perhaps best demonstrated with this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YGUTc.jpg&quot; alt=&quot;Malacca Flight Track&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Malaysia published two maps with the preliminary accident report which allege MH370 flew west from Penang to MEKAR (above Aceh Province) and then between 18:25 UTC and 19:41 UTC flew west into the Indian Ocean. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is the Burst Offset Frequency chart published 24 March shows a frequency drop after 18:25 UTC signifying flight away from the satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After MH370 allegedly emerged from the Straits and turned south the track which Malaysia's Preliminary Accident Report claims MH370 flew (based on their analysis of the BOF chart data) the track makes even less sense because the distances away from the satellite continue to increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vFLWM.jpg&quot; alt=&quot;BOF track + Satellite position&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this image shows the distance relationship with the satellite:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/x72GR.jpg&quot; alt=&quot;Track displacement from satellite&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also other (non satellite) reasons to question the validity of the alleged track through the Straits of Malacca. First is the claim MH370 was seen flying west by radar at Surat Thani in Thailand. That radar has a published maximum range of 200nm. Kota Bharu is 240nm away from Surat Thani.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ImSry.jpg&quot; alt=&quot;Surat Thani radar radius 92nm &amp;amp; 140nm&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not the only reason to doubt the alleged MH370 flight though the Straits. Malaysia presented this image to Chinese relatives at the Lido hotel in Beijing on 21 March and told them it was a military radar image from Butterworth of MH370 in the Straits of Malacca. They said it crossed the island of Pelau Perak at 18:02 UTC and disappeared at 18:22 UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XlPU6.jpg&quot; alt=&quot;Lido Hotel image&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image however omits other aircraft known to be present at the same time: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZpJxG.jpg&quot; alt=&quot;UAE343 overlay&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Worst inconsistency of all however is this, the radar image does not even come from the Butterworth radar. The real military radar used by Butterworth is a Thales Raytheon GM400 which has a screen display like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sel7k.jpg&quot; alt=&quot;Thales Raytheon GM400&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't understand how so many supposedly intelligent &quot;experts&quot; and journalists have managed to be deceived for so long except to say people believe only what they want to believe and shut their eyes to the truth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Australian, Malaysian, Japanese, New Zealand and Chinese taxpayers collectively forked out $90m wasted taxpayer dollars for a search at the end of this projected BOF track in April which turned up no result.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is how does this mutually incompatible information prove MH370 flew west through the Straits at all? &lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="2357" LastEditDate="2014-07-23T03:43:32.240" LastActivityDate="2014-07-23T03:43:32.240" Title="How could MH370 fly west when satellite pings went east?" Tags="&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="12" ClosedDate="2014-05-16T19:03:47.670" ContentLicense="CC BY-SA 3.0" />
  <row Id="3932" PostTypeId="2" ParentId="1609" CreationDate="2014-05-16T00:05:34.717" Score="-4" Body="&lt;p&gt;I think most are simply thinking too much.  The easiest and likely the most complete answer is resistance (or friction).  High altitude air is less dense, making it easier to pass through.  Oxygen content in high altitude is exactly the same as sea level.  While the air up there is the same air we breath, there is less of that air in the same volume container. &#xA;Space vehicles do not use jet engines.  To turn or do any movement actually they have &quot;jets&quot; in various locations around the shuttle.  &quot;Jets&quot; in this case are not jet engines, they are simply small nozzles that pressurized gases gets released through.  Keep in mind that with zero air, there is no resistance to movement, remember newton's laws of motion: every action has an equal an opposite reaction.&lt;/p&gt;&#xA;" OwnerUserId="2358" LastActivityDate="2014-05-16T00:05:34.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3933" PostTypeId="1" CreationDate="2014-05-16T02:00:22.600" Score="3" ViewCount="544" Body="&lt;p&gt;Can someone please explain the inconsistency in MH370's alleged track after take off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GczQY.jpg&quot; alt=&quot;Alleged flight over Malay Peninsula&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The satellite handshake offset frequency shows an increase after take off until 16:55 UTC, then a reduction in frequency until 17:07 UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A frequency increase means signal compression, in other words flying west towards INMARSAT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is after take off at 16:41 UTC MH370 was tracked by radar flying steadily east until reaching BITOD (east of IGARI) when tracking ceased at about the radar horizon. MH370 was never spotted on radar east of the Malay peninsula flying back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the preliminary accident report released on May 1st by the Malaysian Government it is shown flying back to Penang. Radar tracking imagery from Butterworth shown to relatives at Beijing on 21 March shows a target flying from Penang at 18:02 UTC across VAMPI and reaching MEKAR at 18:22 UTC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is why the satellite handshake data does not match the claimed track?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frequency increase implies MH370 flew west after 17:07 UTC, but the radar/transponder  data says it continued east until at least 17:24 UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other problem is that after 18:25 UTC the satellite data implies MH370 flew away from the satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The satellite movement from take-off until 19:41 UTC was northward from the horizon and INMARSAT's displacement does not seem sufficient to cause the inconsistency.    &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T04:15:25.810" Title="Why does MH370 Satellite data disagree with track after take off?" Tags="&lt;mh370-incident&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2014-05-16T16:34:36.197" ContentLicense="CC BY-SA 3.0" />
  <row Id="3934" PostTypeId="2" ParentId="3902" CreationDate="2014-05-16T02:08:04.767" Score="6" Body="&lt;p&gt;In flight the wing is generating upward lift, the tail plane a downward force. As you move the c.g. forward, more downward force is required from the tail plane, which means the tail plane is causing more drag, which means you will burn more fuel. Move the c.g. aft and you'll burn less fuel. However, the farther aft you move the c.g., the less stable the airplane becomes in response to gusts. As an example, 747 freighter operators typically aim for a zero fuel weight c.g. of 26% MAC (mean aerodynamic chord) as an optimal balance.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-05-16T02:15:20.480" LastActivityDate="2014-05-16T02:15:20.480" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3935" PostTypeId="2" ParentId="3789" CreationDate="2014-05-16T02:55:08.467" Score="2" Body="&lt;p&gt;Vaslan developed an STC for a two man Boeing 727 cockpit on the re-engined B727-RE. This required automation of fuel management systems, hydraulics, electricals and pneumatic systems and repositioning these to the overhead P-5 panel. The pedastal was also extended rearwards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of VIP B727s flying with all glass EFIS cockpit panels. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually a cockpit redesign will feature a suite of instrument products from one manufacturer for example like Rockwell-Collins, or Smiths etc and present it as an integrated platform.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know who owns the STC currently but in theory if you wanted to the conversion could be carried anywhere out through a sub-contractor.    &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T02:55:08.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="3936" PostTypeId="2" ParentId="3782" CreationDate="2014-05-16T03:09:11.137" Score="0" Body="&lt;p&gt;Airframe heating is a big barrier to any airframe design and in consequence the fuselage needs to be able to grow longitudinally. The pressure hull needs to be encased inside a flexible, expandable sleeve-like skin. It requires the use of a great deal of heat resistant titanium and you can't use normal tools on the titanium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Various issues could be overcome but you would need to develop a supersonic inlet with variable geometry surfaces to close and slow down air entering the engines at supersonic speed, or open to allow maximum airflow at subsonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The development cost would be huge which is why I think the economics actually require a people mover rather than a VIP airframe with a limited market. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The market is definitely trans Pacific and trans Atlantic. Concorde never had the range for trans-Pacific. If you had the backing of say Singapore Airlines, Japan Airlines or a Big Chinese airline as a launch customer to operate trans Pacific then you would have some prospect of launching a new design. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the Chinese in particular this would be a spectacular prestige product.      &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T03:09:11.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3937" PostTypeId="2" ParentId="3807" CreationDate="2014-05-16T03:20:15.997" Score="0" Body="&lt;p&gt;The greatest danger appears to be when an aircraft is flying slowly, with landing gear open  and there are cell towers on hills level with the approach path, because these are circumstances when a cell phone is most likely to make a call connection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many years ago working as an airline baggage handler in a country which prohibited all cell phone use during commercial flights, I was astonished to hear baggage carts with phones ringing all the time and it is the airport baggage halls where one could implement this policy or at the check-in counters. I imagine airlines would not be too keen on the extra manpower and wages required.      &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T03:20:15.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3939" PostTypeId="2" ParentId="3931" CreationDate="2014-05-16T05:04:21.000" Score="7" Body="&lt;p&gt;You have an error in one of your major premises.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say &quot;satellite pings went east&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That can't be derived from the data you have shown. &lt;a href=&quot;http://theaviationist.com/2014/03/27/inmarsat-helps-finding-route/&quot;&gt;The chart is showing Doppler shift&lt;/a&gt;. A westbound aircraft that is decelerating, or simply decreasing its component of velocity toward the satellite (by, for example, turning slightly southbound) will result in a change in the Doppler shift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deviations up and down on that chart don't correspond to the &lt;em&gt;velocity&lt;/em&gt; being east or westbound, but &lt;em&gt;accelerations&lt;/em&gt; towards or away from the satellite.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorDisplayName="user2168" LastEditDate="2014-05-16T05:09:41.990" LastActivityDate="2014-05-16T05:09:41.990" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="3941" PostTypeId="1" CreationDate="2014-05-16T06:19:21.970" Score="-1" ViewCount="599" Body="&lt;p&gt;This image illustrates my question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KTWX2.jpg&quot; alt=&quot;Satellite distance displacements&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Burst Offset Frequency chart from 19:41 UTC until the final ping at 00:11 UTC the blue track for MH370 shows increasing frequency, which means flying towards the satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore for the Burst Offset Frequency chart to be correct the flight track in maps released by the preliminary accident report should have curved west not east.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they were fundamentally so wrong how could this ping chart ever have been used to plot the final location of MH370?  &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T14:28:23.043" Title="Why do MH370 Indian Ocean INMARSAT distances increase when they should decrease?" Tags="&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2014-05-16T14:41:39.770" ContentLicense="CC BY-SA 3.0" />
  <row Id="3942" PostTypeId="2" ParentId="3306" CreationDate="2014-05-16T06:31:18.063" Score="2" Body="&lt;p&gt;Pusher props offer a real advantage to small amphibians like the Lake Buccaneer and the Republic See Bee where pilots need to be able to jump out and catch mooring buoys, lines or jetties without fear of striking a spinning prop blade.&lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-05-16T06:31:18.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="3943" PostTypeId="2" ParentId="3888" CreationDate="2014-05-16T06:37:15.507" Score="-3" Body="&lt;p&gt;I took off once at Wellington airport, NZ in a Gulfstream Cheetah in winds gusting to 55kt. When I opened the throttle it lifted off with no forward ground speed at all. All that is required is a vessel fast enough to provide a steady 45kt wind speed over the decks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some designs of fast ferries like the INCAT wavepiercing catamarans would be ideally suited as some form of aircraft carriers like this.  &lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="64" LastEditDate="2014-06-20T16:42:39.437" LastActivityDate="2014-06-20T16:42:39.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4942" PostTypeId="2" ParentId="3941" CreationDate="2014-05-16T12:45:12.753" Score="1" Body="&lt;p&gt;It seems to me that your question is based on a misinterpretation of the data, as already noted in &lt;a href=&quot;https://aviation.stackexchange.com/a/3939/1467&quot;&gt;this aswer&lt;/a&gt; to another (extremely similar) question you asked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the Burst Offset Frequency chart from 19:41 UTC until the final ping at 00:11 UTC the blue track for MH370 shows increasing frequency&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That is a statement that contradicts itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chart shows the &lt;em&gt;offset&lt;/em&gt;, &lt;strong&gt;not&lt;/strong&gt; the &lt;em&gt;frequency&lt;/em&gt;, an increasing offset can mean both decreasing or increasing frequency, depending on the sign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most likely only the absolute value of the offset has been plotted for convinience.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-05-16T14:28:23.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4943" PostTypeId="2" ParentId="3899" CreationDate="2014-05-16T15:42:57.640" Score="2" Body="&lt;p&gt;Propeller driven aircraft usually have a better acceleration/deceleration rate compared to similar jet driven aircraft. This, combined with a straight/tapered wing, instead of a swept wing, and large blown flaps (as stated by fooot) make an aircraft which is able to take-off and land on very short runways.&lt;/p&gt;&#xA;" OwnerUserId="2362" LastActivityDate="2014-05-16T15:42:57.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4944" PostTypeId="5" CreationDate="2014-05-16T19:33:57.207" Score="0" Body="&lt;p&gt;This tag is about the operation and maintenance of radio systems. Questions about radio etiquette should go in &lt;a href=&quot;http://aviation.stackexchange.com/tags/radio-communications/infohttp://aviation.stackexchange.com/tags/radio-communications/info&quot;&gt;radio-communications&lt;/a&gt; instead.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-04-23T02:14:19.267" LastActivityDate="2015-04-23T02:14:19.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4945" PostTypeId="4" CreationDate="2014-05-16T19:33:57.207" Score="0" Body="Radio equipment, including antennas, receivers, two-way radio systems, and more." OwnerUserId="65" LastEditorUserId="3170" LastEditDate="2015-04-23T02:14:03.157" LastActivityDate="2015-04-23T02:14:03.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4946" PostTypeId="5" CreationDate="2014-05-16T19:34:56.223" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-05-16T19:34:56.223" LastActivityDate="2014-05-16T19:34:56.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4947" PostTypeId="4" CreationDate="2014-05-16T19:34:56.223" Score="0" Body="Questions about the legendary Aérospatiale-BAC Concorde." OwnerUserId="65" LastEditorUserId="22726" LastEditDate="2019-01-25T08:33:06.437" LastActivityDate="2019-01-25T08:33:06.437" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="4950" PostTypeId="1" AcceptedAnswerId="4951" CreationDate="2014-05-16T22:11:59.113" Score="12" ViewCount="20138" Body="&lt;p&gt;I know that there is a written exam that you are required to take, but do you have to go to a class in order to study for that test?  If I'm really good at just learning from a book, can I just learn that way, maybe take a couple practice tests and then take the exam?  Or are they going to need proof that I went to some certified class?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More subjectively: Assuming it's allowable, is it a bad idea?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-05-17T04:58:35.093" LastActivityDate="2019-05-20T13:27:12.083" Title="Is ground school required to get a Private Pilots License?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;ppl&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4951" PostTypeId="2" ParentId="4950" CreationDate="2014-05-16T22:51:21.417" Score="12" Body="&lt;p&gt;In Canada, you are required to have 40 hours of ground school instruction. See &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/regserv/cars/part4-standards-421-1086.htm&quot;&gt;Canadian Aviation Regulations 421.26 (3)(a)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;completed a minimum of 40 hours private pilot aeroplane ground school instruction on the following subjects ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ground school instruction is defined as (&lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/page-72.html?texthighlight=ground%20school#s-400.01&quot;&gt;CARS 400.01&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;classroom-type instruction generally given to one or more persons and covering an organized program of lectures, homework or self-paced study that adheres to an approved training program.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, you &lt;em&gt;can&lt;/em&gt; learn by self-study, but it needs to be an approved training program. This would mean that a flight instructor would need to sign off on the self-study program.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/training_testing/training/pilot_tips/&quot;&gt;The FAA says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you are unable to attend a ground school, the self-study method can be satisfactory, provided you obtain the proper study materials and devote a reasonable amount of time to study.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The regulation is at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b6f202aa716caae49cfba7ccd4a2c696&amp;amp;node=14:2.0.1.1.2.1.1.23&amp;amp;rgn=div8&quot;&gt;Title 14 Code of Federal Regulations, §61.35(a)(1)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Received an endorsement, if required by this part, from an authorized instructor certifying that the applicant accomplished the appropriate ground-training or a home-study course required by this part for the certificate or rating sought and is prepared for the knowledge test ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Because in both cases an instructor must sign off on your preparedness for the examination, and passing the examination demonstrates that you meet the standard, in my opinion, the only thing that would make self-study a bad idea is if self-study is not an effective learning method for you, which could delay your training.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorDisplayName="user2168" LastEditDate="2014-05-16T23:04:06.307" LastActivityDate="2014-05-16T23:04:06.307" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4952" PostTypeId="1" AcceptedAnswerId="4958" CreationDate="2014-05-17T05:33:34.477" Score="-6" ViewCount="298" Body="&lt;p&gt;I read this from the new CNN.com: &lt;a href=&quot;http://cnn.com/video/data/2.0/video/us/2014/05/16/erin-air-traffic-control-error-responsible-for-near-mid-air-collision.cnn.html&quot; rel=&quot;nofollow&quot;&gt;Two planes nearly collide over Pacific&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The death toll would amount more than the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow&quot;&gt;Tenerife&lt;/a&gt;'s one if things went actually wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kevin Townsend tells more in his post: &lt;a href=&quot;https://medium.com/medium-long/c2f8d68a917c&quot; rel=&quot;nofollow&quot;&gt;Two Weeks Ago, I Almost Died in the Deadliest Plane Crash Ever&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;My question is:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Can the passengers ask for some compensation (damages or whatever) due to the event?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="64" LastEditDate="2014-05-17T22:59:04.937" LastActivityDate="2014-05-17T22:59:04.937" Title="Incident over the pacific" Tags="&lt;tcas&gt;" AnswerCount="1" CommentCount="11" ClosedDate="2014-05-17T17:45:48.783" ContentLicense="CC BY-SA 3.0" />
  <row Id="4953" PostTypeId="1" CreationDate="2014-05-17T06:14:50.987" Score="25" ViewCount="25115" Body="&lt;p&gt;Has any propeller driven aircraft ever achieved and sustained supersonic speed? If not, why can't propeller airplanes achieve that speed?&lt;/p&gt;&#xA;" OwnerUserId="177" LastEditorUserId="1696" LastEditDate="2015-02-19T23:27:12.763" LastActivityDate="2016-06-07T06:01:03.833" Title="Can propeller driven aircraft sustain speeds at or above Mach 1?" Tags="&lt;propeller&gt;&lt;supersonic&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4954" PostTypeId="2" ParentId="4953" CreationDate="2014-05-17T08:19:34.440" Score="19" Body="&lt;p&gt;Supersonic level flight?  No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fastest propeller-driven aircraft is either the turboprop-powered &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-114&quot;&gt;TU-114&lt;/a&gt; with a measured top speed of Mach 0.73 or the turboprop-powered &lt;a href=&quot;https://en.wikipedia.org/wiki/Republic_XF-84H&quot;&gt;XF-84H &quot;Thunderscreech&quot;&lt;/a&gt; with a design top speed of Mach 0.9 and an actual top speed of either Mach 0.83 or Mach 0.7 (sources disagree).  The latter is an indication of why supersonic propeller-driven aircraft are unlikely: the continuous sonic boom coming off the propeller tips made the Thunderscreech the loudest airplane in the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The record for piston-engine aircraft is slightly lower, at &lt;a href=&quot;https://en.wikipedia.org/wiki/Rare_Bear&quot;&gt;Mach 0.71&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-05-17T08:19:34.440" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="4955" PostTypeId="1" AcceptedAnswerId="4956" CreationDate="2014-05-17T08:39:25.893" Score="3" ViewCount="550" Body="&lt;p&gt;What planes are the key players in military airlifting?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the C-130J, C-17 and A400M are among them, what others are there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the key differences between the above mentioned planes?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="3504" LastEditDate="2015-03-23T11:38:00.183" LastActivityDate="2015-03-23T11:38:00.183" Title="What types of aircraft perform military airlift operations?" Tags="&lt;military&gt;&lt;transport-category&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4956" PostTypeId="2" ParentId="4955" CreationDate="2014-05-17T09:42:31.923" Score="18" Body="&lt;p&gt;There is no single &quot;key player&quot;. It depends on the task. You need big, long-haul transporters like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot;&gt;C-5&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot;&gt;An-124&lt;/a&gt; to move large amounts of troop and equipment quickly. This is called strategic airlifting and is done with turbofan-powered aircraft which are similar to airliners. But they need prepared and secured air strips of considerable length (the NATO standard airstrip is 8000ft long).&lt;BR&gt;And then you need tactical transporters which can fly as close to the action as possible, and they must have STOL capabilities and defensive equipment to survive their missions. This requires mostly turboprop powered planes like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot;&gt;C-130&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Transall_C-160&quot;&gt;C-160&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-12&quot;&gt;An-12&lt;/a&gt; for big equipment or the &lt;a href=&quot;http://en.wikipedia.org/wiki/CASA/IPTN_CN-235&quot;&gt;CASA 235&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-26&quot;&gt;An-26&lt;/a&gt; for smaller units or parts. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot;&gt;C-17&lt;/a&gt; was meant to be a strategic airlifter with some tactical capabilities, but it cannot replace the smaller turboprops entirely. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A400M_Atlas&quot;&gt;A-400&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-70&quot;&gt;An-70&lt;/a&gt; are large tactical transports with some strategic capabilities, but this comes at the expense of usability on unprepared or improvised airstrips.&lt;BR&gt;&#xA;And then you need helicopters for the missions which require the highest amount of flexibility and closeness to the action.&lt;p&gt;&#xA;All three depend on the other, and only together they become effective. That is why I cannot give you a key player.&#xA;&lt;P&gt;&#xA;Key characteristics of strategic transporters:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;turbofan engines&lt;/li&gt;&#xA;&lt;li&gt;swept wings, high flight Mach number and range&lt;/li&gt;&#xA;&lt;li&gt;high wing, so the fuselage is close to the ground for easy loading and unloading&lt;/li&gt;&#xA;&lt;li&gt;large nose doors and/or ramp in rear fuselage.&#xA;&lt;P&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Key characteristics of tactical transporters:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;turboprop engines (mostly)&lt;/li&gt;&#xA;&lt;li&gt;straight wings with extensive high-lift devices for STOL capabilities&lt;/li&gt;&#xA;&lt;li&gt;moderate flight Mach number and range&lt;/li&gt;&#xA;&lt;li&gt;high wing, so the fuselage is close to the ground for easy loading and unloading, low loading of landing gear for soft ground capabilities&lt;/li&gt;&#xA;&lt;li&gt;ramp in rear fuselage.&#xA;&lt;P&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Key characteristics of helicopters&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;that whirly thing on top&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-16T14:17:52.750" LastActivityDate="2014-11-16T14:17:52.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4957" PostTypeId="2" ParentId="4955" CreationDate="2014-05-17T11:06:27.573" Score="7" Body="&lt;p&gt;In the past, the military has contracted a great deal of their airlifting, both of personnel and freight, to commercial carriers. If you include this activity, a number of other airplanes would have to be included, and of these, the 747 would be the workhorse of the group, especially in the 1990s. In addition to regular, ongoing military contracts and charters, they also had the CRAF (Civil Reserve Aircraft Fleet) program in which they subsidized the conversion of 747 pax aircraft to freighters with the proviso that if there was a CRAF activation, those aircraft and their civilian crews would be at the disposal of the military. Indeed, when Operation Desert Shield came along, there was a CRAF activation from 17 Aug 1990 to 24 May 1991.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-17T11:06:27.573" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="4958" PostTypeId="2" ParentId="4952" CreationDate="2014-05-17T11:24:44.340" Score="3" Body="&lt;p&gt;I am not a lawyer. None of this should taken as, or construed to be legal advice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking over United's &lt;a href=&quot;https://www.united.com/web/format/pdf/Contract_of_Carriage.pdf&quot; rel=&quot;nofollow&quot;&gt;Contract of Carriage&lt;/a&gt; upon which their passenger bill of rights are based, I found this paragraph:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;UA shall not be liable for any death, injury, delay, loss or other damage of whatsoever nature (hereafter referred to collectively as “damage”) arising out of or in connection with carriage or other services performed by UA, unless such damage is proven to have been caused by the sole negligence or willful misconduct of UA and there has been no contributory negligence on the part of the Passenger&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One of the planes involved in the incident to which you refer was a UA flight. They were flying per ATC guidance, therefor there was no &quot;sole negligence or willful misconduct&quot; etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, to answer your given question, &lt;strong&gt;yes&lt;/strong&gt; the passengers can &lt;em&gt;ask&lt;/em&gt; for compensation. They are unlikely to be granted any by the airline, as that would set a bad precedent (not a legal precedent, but one that might affect them legally down the road). They are under no obligation to make compensation, as they fulfilled the contract between themselves and the passengers. The passengers were safely delivered to their destination with little to no delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my personal opinion, the airline owes nothing to any of the passengers, even for &quot;mental anguish&quot; as the total deviation from flight path was well within the amount that could be seen or felt due to &lt;a href=&quot;http://www.navyaircrew.com/blog/2009/08/30/light-moderate-or-severe-turbulencehow-are-they-defined/&quot; rel=&quot;nofollow&quot;&gt;severe turbulence&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2014-05-17T11:33:55.460" LastActivityDate="2014-05-17T11:33:55.460" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="4959" PostTypeId="2" ParentId="3685" CreationDate="2014-05-17T20:08:28.663" Score="4" Body="&lt;p&gt;This will be quoted from the &lt;a href=&quot;http://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=12&amp;amp;ved=0CH4QFjAL&amp;amp;url=http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=B_NG-Landing_Gear.pdf&amp;amp;ei=gbl3U6GUFejesASbpYDYCw&amp;amp;usg=AFQjCNGL7-9s1-s8642vtECRcGF8z1mHvw&amp;amp;sig2=pLfVlGr_xpFPMh9hBXN7LQ&amp;amp;bvm=bv.66917471,d.cWc&amp;amp;cad=rja&quot; rel=&quot;nofollow&quot;&gt;B737 NG - Systems Summary [Landing Gear]&lt;/a&gt; which isn't an official Boeing document, but ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Page 5&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Landing&lt;/strong&gt;&lt;br&gt;&#xA;  When a landing autobrake selection is made, the system performs a turn-on-self-test. If the turn-on-self-test is not successful, the AUTO BRAKE DISARM light illuminates and the autobrake system does not arm.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Four levels of deceleration can be selected for landing. However, on dry runways, the maximum autobrake deceleration rate in the landing mode is less than that produced by full pedal braking.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;After landing, the autobrake application begins when:&lt;br&gt;&#xA;   - both forward thrust levers are retarded to IDLE&lt;br&gt;&#xA;   - the main wheels spin-up  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE&lt;/strong&gt;: Landing autobrake settings may be selected after touchdown prior to decelerating through 60 kts of ground speed. Braking initiates immediately if the above conditions are met.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;To maintain the selected landing deceleration rate, autobrake pressure is reduced as other controls, such as thrust reversers and spoilers (without disarming the system) by rotating the selector. The autobrake system brings the airplane to a complete stop unless the braking is terminated by the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, reading between the lines here, if the autobrake system has not been activated, upon touchdown it &lt;em&gt;can&lt;/em&gt; be activated, before slow down to 60kts ground speed, as long as all other stipulations are met. Also, although the sentence as written, is confusing, the last paragraph indicates that the level of braking can be changed &lt;em&gt;during&lt;/em&gt; autobraking, by turning the selector &lt;strong&gt;AND&lt;/strong&gt; that will not disarm the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know this is not official documentation and is an older model plane, but thought I'd offer it up.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-05-17T20:08:28.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4960" PostTypeId="2" ParentId="3899" CreationDate="2014-05-17T22:55:37.683" Score="19" Body="&lt;p&gt;&lt;strong&gt;Assault Takeoff/Landing Technique&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a significant reason for the C-130's performance that you witnessed. &quot;Assault&quot; takeoff/landing speeds are lower than normal speeds, and closer to stall speed. Also there are some weight limitations. Further, the crew must be specifically trained. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Stopping Quickly&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea of a smooth landing is thrown out the window. The intent is to &quot;plant&quot; the wheels at about 300 feet down the runway. That is, transition immediately from approach attitude to actually landing rather than assuming a touch-down attitude and letting the aircraft float down to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose gear is &lt;em&gt;pushed&lt;/em&gt; to the ground and the instant the wheels are on the ground the props are thrown into full reverse, now pushing air forward. At the same time the pilot puts all his might into mashing the brakes. He would &quot;stand on the brakes&quot; as we say. The yoke is also pushed full forward which puts as much weight as possible on the landing gear. The anti-lock brake system is critical here, preventing skidding out of control and blown tires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Vietnam, in combat conditions, 130 pilots would put the props in reverse before touching down. If you've seen the video on YouTube of a C-130 landing on an aircraft carrier, they did it there too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;J's Props are a Huge factor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The performance boost of the J models thanks to the new prop and engine is amazing vis-a-vis the older models. But fundamental airframe limitations are still there. Nonetheless more blades (6 vice. 4) and the &quot;un-ducted fan&quot; design simply pushes more air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Show Off Configuration&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An empty airplane with a light fuel load of course maximizes the short takeoff and landing performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;C-130 Has Fowler Flaps&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not blown flaps. Just because the props push air over the wing does not make it &lt;a href=&quot;http://en.wikipedia.org/wiki/Blown_flap&quot;&gt;blown flaps&lt;/a&gt;. Otherwise, yes, the C-130 was given lots of flapage precisely for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastEditorUserId="1798" LastEditDate="2014-05-20T02:39:56.007" LastActivityDate="2014-05-20T02:39:56.007" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4961" PostTypeId="1" CreationDate="2014-05-18T00:08:36.210" Score="7" ViewCount="445" Body="&lt;p&gt;A book I have (&lt;em&gt;Boeing, Planemaker to the World&lt;/em&gt;) includes how many orders and planes received of all of Boeing's major models as of the date it was printed. It said the 2707 (Boeing's failed SST) got 125 orders. That seems a lot, compared to the very small amount of concordes and TU-144s that were ever made. What made the 2707 so superior that 125 of them were ordered?&lt;/p&gt;&#xA;" OwnerUserId="1015" LastActivityDate="2014-05-18T07:15:45.527" Title="What made the 2707 so superior?" Tags="&lt;boeing&gt;&lt;supersonic&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4962" PostTypeId="1" CreationDate="2014-05-18T00:19:34.803" Score="8" ViewCount="3736" Body="&lt;p&gt;Once, a while ago, I tried to create a Flight Simulator X model for an aircraft that I wanted a model of, but was soon overwhelmed by having to guess so much of the flight dynamics. Is there somewhere where I could get detailed information about the flight dynamics of aircraft without contacting the manufacturer, a pilot, or having the plane itself to run tests on? I mean for things like drag at different mach, drag coefficient created by the landing gear, lift coefficient created by the flaps, detailed stuff about the engines, etc.&lt;/p&gt;&#xA;" OwnerUserId="1015" LastActivityDate="2017-05-02T12:26:20.087" Title="Where to get flight dynamics for a flight sim model?" Tags="&lt;aerodynamics&gt;&lt;flight-simulator&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4963" PostTypeId="2" ParentId="4961" CreationDate="2014-05-18T01:00:22.703" Score="5" Body="&lt;p&gt;The plane was designed for a &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_2707#Design_competition&quot;&gt;US funded competition which it won&lt;/a&gt;, after it would get 1 million dollars in funding for further development which automatically means that the 2707 would be the cheaper plane to buy and that it had the US Government Stamp of Approval. This also meant that there were political reasons to commit to buy one of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason it won that competition is because it was slightly less loud, slightly more efficient and more technologically advanced than its competition.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-05-18T01:16:59.607" LastActivityDate="2014-05-18T01:16:59.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4964" PostTypeId="2" ParentId="4962" CreationDate="2014-05-18T01:23:37.303" Score="2" Body="&lt;p&gt;I'm not sure if this will help you but &lt;a href=&quot;http://www.megginson.com/Aviation/roskam-coefficients.html&quot; rel=&quot;nofollow&quot;&gt;check here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1913" LastEditorUserId="65" LastEditDate="2015-03-30T13:23:12.697" LastActivityDate="2015-03-30T13:23:12.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4965" PostTypeId="2" ParentId="4953" CreationDate="2014-05-18T01:41:59.170" Score="15" Body="&lt;p&gt;According to Wikipedia:&#xA;&quot;The tip of the propeller on many early aircraft may reach supersonic speeds, producing a noticeable buzz that differentiates such aircraft. This is particularly noticeable on the Stearman, and noticeable on the North American T-6 Texan when it enters a sharp-breaking turn. This is undesirable, as the transonic air movement creates disruptive shock waves and turbulence. It is due to these effects that propellers are known to suffer from dramatically decreased performance as they approach the speed of sound. It is easy to demonstrate that the power needed to improve performance is so great that the weight of the required engine grows faster than the power output of the propeller can compensate. This problem was one that led to early research into jet engines...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically the performance drops so badly that you better switch to jet engines. In fact when designing the blades, a max tip Mach of ~.9 is a hard limit of design. The text continues to say that nevertheless some propeller aircrafts were able to approach speed of sound in a dive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.m.wikipedia.org/wiki/Sound_barrier&quot;&gt;http://en.m.wikipedia.org/wiki/Sound_barrier&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1913" LastEditorUserId="1913" LastEditDate="2015-06-19T09:24:34.133" LastActivityDate="2015-06-19T09:24:34.133" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4966" PostTypeId="1" AcceptedAnswerId="4969" CreationDate="2014-05-18T04:15:08.527" Score="54" ViewCount="221781" Body="&lt;p&gt;I'm not an aircraft expert and I just realized that there are two different terms - turbofan and turboprop. I always had them combined in my head as a term for a large jet engine (like you would see on a 747). Apparently this is not the case though. So what is the difference between them? Are there other types of &quot;turbo&quot; engines?&lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="567" LastEditDate="2014-12-17T17:16:37.497" LastActivityDate="2019-07-16T07:46:41.013" Title="What is the difference between a turbofan and a turboprop engine?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;turboprop&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="4967" PostTypeId="1" CreationDate="2014-05-18T04:19:34.690" Score="4" ViewCount="1596" Body="&lt;p&gt;How can you select best cruise altitude (altitude for best range velocity) and maximum speed altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific case is a turboprop aircraft of gross weight 8000 lb.&lt;/p&gt;&#xA;" OwnerUserId="2365" LastEditorUserId="1696" LastEditDate="2015-02-20T18:12:53.150" LastActivityDate="2015-02-20T18:12:53.150" Title="How can you find the best altitude for range or speed?" Tags="&lt;aircraft-design&gt;&lt;density-altitude&gt;&lt;cruise&gt;&lt;range&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4969" PostTypeId="2" ParentId="4966" CreationDate="2014-05-18T05:23:32.153" Score="86" Body="&lt;p&gt;Both engines use a turbine for power. This is where the &quot;turbo&quot; part of the name comes from. In a turbine engine, air is compressed and then fuel is ignited in this compressed air. The energy produced by the ignition turns the turbine. The turbine is then able to drive both the compressor at the front of the engine and also some useful load. In airplanes, it produces thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first jet engine was a &lt;strong&gt;turbojet&lt;/strong&gt;. This is a simple turbine engine that produces all of its thrust from the exhaust from the turbine section. However, because all of the air is passing through the whole turbine, all of it must burn fuel. This means it is inefficient, and the solution is the turbofan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8BkMh.png&quot; alt=&quot;Jet engine schematic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In a &lt;strong&gt;turbofan&lt;/strong&gt;, the turbine primarily drives a fan at the front of the engine. Most engines drive the fan directly from the turbine. There are usually at least two separate shafts to allow the fan to spin slower than the inner core of the engine. The fan is surrounded by a cowl which guides the air to and from the fan. Part of the air enters the turbine section of the engine, and the rest is bypassed around the engine. In high-bypass engines, most of the air only goes through the fan and bypasses the rest of the engine and providing most of the thrust.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ryeeA.png&quot; alt=&quot;Turbofan engine schematic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In a &lt;strong&gt;turboprop&lt;/strong&gt;, the turbine primarily drives a propeller at the front of the engine. There is no cowl around the prop. Some air enters the turbine, the rest does not. The propeller is geared to allow it to spin slower than the turbine. Although this diagram shows only a single shaft, many turboprops have two, with a high pressure shaft driving the compressor and a low pressure shaft driving the propeller. Some engines such as the popular &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot;&gt;PT6&lt;/a&gt; also reverse the flow direction multiple times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hD8lr.png&quot; alt=&quot;Turboprop engine schematic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Turboprops are more efficient at lower speeds since the prop can move much more air with a smaller turbine than the fan on a turbofan engine. The cowl around the turbofan's large fan allows it to perform better than an open propeller at high speeds, but limits the practical size of the fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At supersonic speeds, turbojets have more of a performance benefit. They develop all of their thrust from the high velocity turbine exhaust, while turbofans supplement that with the lower velocity air from the fan. Since the air from the fan is also not compressed nearly as much as the core turbine flow, it is also harder to prevent the flow from going supersonic and causing losses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde used turbojets because it was designed to cruise for long periods at supersonic speeds. Modern fighter jet engines are turbofans, which provide a compromise between efficiency and speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other benefits and drawbacks between turbojets, turbofans, and turboprops, but I think they are beyond the scope of this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Work has been done on creating a &quot;propfan&quot; engine, in an attempt to get the efficiency of a turboprop and the speed of a turbofan. They have yet to come up with a viable design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gHaHH.jpg&quot; alt=&quot;Prop fan engine schematic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elsewhere in aviation, turbine engines are used in &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;helicopters, as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6T&quot;&gt;turboshaft engine&lt;/a&gt; driving the rotors instead of a propeller, and with a freewheeling clutch to enable autorotations&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Auxiliary_power_unit&quot;&gt;APU&lt;/a&gt;s in jet aircraft and large turboprop aircraft&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Turbines also find use outside of aviation in power plants (to generate electricity), and even vehicles (like the Abrams tank).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbocharged piston engines use a turbine much differently from the examples above. Instead of being the primary power source, the turbine only assists the piston engine. A turbocharger uses a turbine to compress air sent to the engine intake. The increased compression helps the engine generate more power. The turbine of a turbocharger is driven by engine exhaust gasses, and a supercharger is similar but is directly powered by the engine. See the &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbocharger&quot;&gt;Wikipedia page&lt;/a&gt; for more detail.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="3504" LastEditDate="2015-01-04T18:24:55.260" LastActivityDate="2015-01-04T18:24:55.260" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="4970" PostTypeId="2" ParentId="4967" CreationDate="2014-05-18T06:48:23.110" Score="10" Body="&lt;p&gt;Generally, climbing as high as you can would be close to the optimum strategy. In the end, the altitude is given by the optimum lift coefficient in cruise, which can be approximated as $$c_L = \sqrt{\frac{1-n_v}{n_v+3}\cdot \pi \cdot AR \cdot \epsilon \cdot c_{D0}}$$&#xA;Now it will be important to get the thrust over speed dependency right, which is expressed with $n_v$. A turboprop should have $n_v \approx -0.7$. The rest is determined by the aerodynamics of your plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient&lt;br&gt;&#xA;    $n_v \:\:\:$  thrust exponent, as in $T \sim v^{n_v} $&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have the optimum $c_L$, you need to find the altitude where level flight at cruise power will require this lift coefficient. Depending on the range of your small aircraft, you might spend most of the flight in climb and descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maximum speed altitude: Draw the envelope at max power, and look for the rightmost point which can be trimmed. The equation above uses the quadratic polar approximation which works well at high lift coefficients, but for maximum speed the details of friction and parasitic drag are important, and they cannot be captured with a simple formula.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-18T06:48:23.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4971" PostTypeId="2" ParentId="4961" CreationDate="2014-05-18T07:15:45.527" Score="5" Body="&lt;p&gt;Never to have been built could have a lot to do with that superiority. All designs start with high hopes and great specs, and only later, when reality interfers, the numbers have to be revised, mostly downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other factor is size. Being much larger, it could fly more efficiently than the smaller Concorde and Tu-144.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-18T07:15:45.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4972" PostTypeId="2" ParentId="4962" CreationDate="2014-05-18T16:25:55.330" Score="2" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/72/qantas-94-heavy&quot;&gt;Qantas94&lt;/a&gt; notes in his comment, there is little you can do, detailed model of aicrafts are a valuable piece of information, so you must be ready to speand quite a lot of money, either by buying one or by developing your own via an extensive flight campaign and data postprocesing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to settle for a less detailed/precise model, there is &lt;a href=&quot;http://en.wikipedia.org/wiki/United_States_Air_Force_Stability_and_Control_Digital_DATCOM&quot; rel=&quot;nofollow noreferrer&quot;&gt;DATCOM&lt;/a&gt; (also available within &lt;a href=&quot;http://www.mathworks.com/help/aeroblks/digitaldatcomforcesandmoments.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Matlab&lt;/a&gt;) that, given some geometrical details about the aircraft is able to estimate the main aerodynamic parameters. If I am not mistaken, the Roskam parameters reported in mikolchon's &lt;a href=&quot;https://aviation.stackexchange.com/a/4964/1467&quot;&gt;answer&lt;/a&gt; are obtained via DATCOM.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-05-18T16:25:55.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4973" PostTypeId="1" CreationDate="2014-05-18T16:40:50.060" Score="1" ViewCount="433" Body="&lt;p&gt;I went to an airshow recently, and the Thunderbirds performed. However, by the time they finished the startup and flight check ceremonies, bad weather had rolled in. However, they did still taxi into position at the end of the runway to wait for the bad weather to blow over. About 45 minutes to an hour later, they decided visibility was to bad to fly, and they taxied back to the ramp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is if there is a solitaire game built into the Thunderbird flight software or something to keep them from dying of boredom, or if they just stoically stare at the end of the runway.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="247" LastEditDate="2014-05-18T18:07:57.463" LastActivityDate="2014-05-19T00:47:47.127" Title="What do the Thunderbirds pilots do when they can't fly?" Tags="&lt;airshow&gt;&lt;thunderbirds&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4975" PostTypeId="2" ParentId="1609" CreationDate="2014-05-18T18:14:16.167" Score="3" Body="&lt;p&gt;This is because the air is cooler and less dense which means that there is less fuel to air mixture at higher altitudes giving it a better fuel efficiency&lt;/p&gt;&#xA;" OwnerUserId="2368" LastActivityDate="2014-05-18T18:14:16.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4976" PostTypeId="2" ParentId="3679" CreationDate="2014-05-18T20:51:09.280" Score="2" Body="&lt;p&gt;It should normally be dropped about 500ft - 1000ft and below the aircraft's maximum speed for dropping the landing gear so you don't damage it.  If you need more drag to slow down quicker you can drop it a bit higher up.&lt;/p&gt;&#xA;" OwnerUserId="2368" LastActivityDate="2014-05-18T20:51:09.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4977" PostTypeId="2" ParentId="1510" CreationDate="2014-05-18T21:00:25.173" Score="0" Body="&lt;p&gt;Pinkfroot now has a series of apps available on the appstore, windows phone and android store.&#xA;The apps vary from satellite views to actually being able to point your camera at the plane and tells you exactly what plane it is and all the information about it.&#xA;You can check them out here:&lt;a href=&quot;http://my.pinkfroot.com/&quot; rel=&quot;nofollow&quot;&gt;http://my.pinkfroot.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your looking to just listen to atc you can get the app live atc or just go onto their free website and find you airport.&#xA;Check them out here:&lt;a href=&quot;http://www.liveatc.net/&quot; rel=&quot;nofollow&quot;&gt;http://www.liveatc.net/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2368" LastEditorUserId="2368" LastEditDate="2014-05-18T21:06:16.443" LastActivityDate="2014-05-18T21:06:16.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4979" PostTypeId="2" ParentId="4973" CreationDate="2014-05-19T00:47:47.127" Score="3" Body="&lt;p&gt;I would imagine they do the same thing all pilots do when they go to the airport expecting a nice day and wind up grounded by weather: Sit around at the airport with the other pilots and complain about the lousy weather. (In this case, since they're all sitting in position waiting for the weather to clear up any griping was probably done over the radio.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are of course other things they can do, being a fairly well-known demonstration team and an important component of the public relations arm of the US Air Force, for example signing autographs and talking to spectators at the airport.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-19T00:47:47.127" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="4980" PostTypeId="1" AcceptedAnswerId="4986" CreationDate="2014-05-19T06:58:03.397" Score="32" ViewCount="9688" Body="&lt;p&gt;I've noticed that winglets are very rare on small aircraft. I wonder why this is the case. Wouldn't they have the same advantages, especially because they travel at low speed? Or is it just a wrong impression I got and they aren't that rare?&lt;/p&gt;&#xA;" OwnerUserId="744" LastEditorUserId="19" LastEditDate="2015-02-18T20:07:08.393" LastActivityDate="2020-02-18T21:41:08.170" Title="Why is it rare for small aircraft to have winglets?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;winglets&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="4981" PostTypeId="2" ParentId="4980" CreationDate="2014-05-19T07:54:23.570" Score="17" Body="&lt;p&gt;First, winglets look fancy but will not help that much in drag reduction. They were pushed &lt;a href=&quot;https://airinsight.com/winglets-a-triumph-of-marketing-over-reality/&quot; rel=&quot;nofollow noreferrer&quot;&gt;less by engineers than by marketing&lt;/a&gt;, Boeing's in particular. They help a litte in ideal conditions, but in sideslip or at high speed they can quickly increase drag.&#xA;&lt;P&gt;&#xA;Then, most small aircraft are designs from a pre-winglet era. Adding them means to invalidate the type certificate, unless someone takes the initiative to re-certify the aircraft with winglets. I guess nobody has seen this as a profitable endeavor so far.&#xA;&lt;P&gt;&#xA;Gliders benefit from winglets because in competitions they are grouped in classes. Membership of some classes is defined by wingspan. Gliders get better with increasing wingspan, so if regulations limit the lateral extension, the way out is to extend the wings upwards. If there is no such artificial limit, it will in most cases be &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;better to expand the wing in spanwise direction&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="22072" LastEditDate="2020-02-14T11:31:00.260" LastActivityDate="2020-02-14T11:31:00.260" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="4982" PostTypeId="2" ParentId="4980" CreationDate="2014-05-19T08:10:31.297" Score="15" Body="&lt;p&gt;Many small aircraft designs are rather old and winglets were not common on airliners either when they were certified. For airliners that fly 8 or more hours a day saving a few percent on fuel quickly pays off the additional development and certification, so winglets were adopted quickly there. But typical general aviation aircraft does not fly anywhere close to that and the few that fly more and would be worth upgrading (and their owners have money for upgrade) are not enough to make the design and manufacture profitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that winglets did find their way to gliders, especially competition ones, as the little benefit is more noticeable there. They also do appear on some newer designs, most notably the Diamond ones (&lt;a href=&quot;http://en.wikipedia.org/wiki/Diamond_DA20&quot;&gt;DA20&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Diamond_DA40&quot;&gt;DA40&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Diamond_DA42&quot;&gt;DA42&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The situation is very similar to why we don't see more aircraft diesel engines. They are more efficient, use cheaper fuel and are somewhat cheaper to maintain, but the certification is so complicated that there are only few modifications available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also most GA aircraft are not really very efficient to begin with. The DA20-A1 claims glide ratio 14:1 and that is way better than most competitors. Compare with airliners where 18:1 is nothing special (was claimed by A320 some 30 years ago). So winglets are not going to help as much.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-05-19T08:20:26.940" LastActivityDate="2014-05-19T08:20:26.940" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="4983" PostTypeId="2" ParentId="1609" CreationDate="2014-05-19T08:33:39.337" Score="46" Body="&lt;p&gt;For a quick explanation, you need to know that&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thrust is the difference between the entry impulse of the air entering the engine and the exit impulse of the heated fuel-air mixture leaving the engine. Impulse is mass times velocity, and expressed with a mass flow &lt;span class=&quot;math-container&quot;&gt;$\dot m$&lt;/span&gt;, thrust T is &lt;span class=&quot;math-container&quot;&gt;$$T = \dot m \cdot (v_{exit} - v_{entry})$$&lt;/span&gt;&lt;/li&gt;&#xA;&lt;li&gt;The exit impulse is increased by accelerating the airflow through the engine, and the acceleration is achieved by heating the air.&lt;/li&gt;&#xA;&lt;li&gt;Each gram of fuel heats up a given mass of air by a certain number of centigrades. The definition of the energy content of fuels is given as the capacity to &lt;a href=&quot;http://whatis.techtarget.com/definition/British-thermal-unit-Btu&quot; rel=&quot;noreferrer&quot;&gt;heat one pound of water by one degree Fahrenheit&lt;/a&gt;. The definition of one &lt;a href=&quot;http://en.wikipedia.org/wiki/Calorie&quot; rel=&quot;noreferrer&quot;&gt;Calorie&lt;/a&gt; is similar but in metric units. Since the heat capacity of both water and air are almost constant at moderate temperatures, the starting temperature makes little difference to the absolute temperature increase when a given amount of energy is added.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Thermal efficiency&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Thermal efficiency is the ratio between the mechanical work extracted as thrust and the heat energy spent on heating the air, and it is affected indirectly by the flight altitude. Please see the Wikipedia article on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Carnot_cycle&quot; rel=&quot;noreferrer&quot;&gt;Carnot cycle&lt;/a&gt;. This and similar cycles describe the workings of all combustion engines in thermodynamic terms. Basically, it says that the efficiency of a combustion engine cannot be greater than the temperature ratio between the temperature increase from ambient (&lt;span class=&quot;math-container&quot;&gt;$t_{amb}$&lt;/span&gt;) to the maximum temperature &lt;span class=&quot;math-container&quot;&gt;$t_{max}$&lt;/span&gt; of the process, divided by the maximum temperature. All temperatures must be expressed as total temperatures, where 0° means 0&amp;nbsp;K or -273.15°C. Operating in colder air makes the ratio bigger and improves efficiency.&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\eta_t = \frac{t_{max} - t_{amb}}{t_{max}} $$&lt;/span&gt;&#xA;&lt;p&gt;&#xA;If &lt;span class=&quot;math-container&quot;&gt;$t_{amb}$&lt;/span&gt; is 290&amp;nbsp;K (16.85°C or 62°F) and the fuel heats up the air to 1400&amp;nbsp;K (2060°F), the thermal efficiency according to the formula above is 79.3%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At cruise altitude &lt;span class=&quot;math-container&quot;&gt;$t_{amb}$&lt;/span&gt; is only 220&amp;nbsp;K (-53.15°C or -63.7°F), and the same fuel flow relative to air flow will lift the maximum temperature only to 1320&amp;nbsp;K (in reality even less; for more precise reasoning see below). Now the thermal efficiency is 83.33%! If the maximum temperature is maintained, both thrust and thermal efficiency will go up; the latter to 84.3%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, the total efficiency will be lower because we have not included &lt;a href=&quot;https://aviation.stackexchange.com/questions/7910/why-is-a-higher-bypass-ratio-more-efficient-at-lower-speeds&quot;&gt;propulsive efficiency&lt;/a&gt;, friction effects or power offtake by bleed air, pumps and generators. Propulsive efficiency describes &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;how well the acceleration of air&lt;/a&gt; is performed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Heating the fuel-air mixture&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Burning a fuel-air mixture will add thermal energy to it, about &lt;a href=&quot;http://en.wikipedia.org/wiki/Kerosene#Properties&quot; rel=&quot;noreferrer&quot;&gt;43&amp;nbsp;MJ for every kilogram of kerosene&lt;/a&gt; (if we assume complete combustion). The isobaric &lt;a href=&quot;http://en.wikipedia.org/wiki/Heat_capacity&quot; rel=&quot;noreferrer&quot;&gt;heat capacity&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Heat_capacity#Table_of_specific_heat_capacities&quot; rel=&quot;noreferrer&quot;&gt;specific heat of air&lt;/a&gt; (close enough, the mixture has very little fuel but lots of air in it) is 29&amp;nbsp;J per mol and per K, so those 43&amp;nbsp;MJ will heat 1000&amp;nbsp;mol of air by 1483&amp;nbsp;K. The heat capacity changes slightly with humidity and temperature, but little enough that we can consider it constant for this purpose. If the air starts at 220&amp;nbsp;K, precompression in the intake will heat it to approx. 232&amp;nbsp;K, further compression in the engine will heat it up to approx. 600&amp;nbsp;K if we assume a compression ratio of 25, and this is the temperature at the entry of the combustion chamber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those &lt;a href=&quot;http://www.wolframalpha.com/input/?i=mass%20of%201000%20mol%20of%20air&quot; rel=&quot;noreferrer&quot;&gt;1000&amp;nbsp;mol of air weigh about 29&amp;nbsp;kg&lt;/a&gt;, and adding a full kilo of fuel and burning the mixture will heat it to 2083&amp;nbsp;K. If you want more details about the parameters in a typical jet engine, please see the diagram in &lt;a href=&quot;https://aviation.stackexchange.com/questions/11481/why-are-turbine-blades-not-made-out-of-titanium-only-compressor-blades/11483#11483&quot;&gt;this answer&lt;/a&gt;. Since the mixture picks up speed as it burns, the fuel mass is also heated and combustion is never complete, the maximum temperature given here will not be reached in reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we start on the ground with an air temperature of 290&amp;nbsp;K, the temperature in the intake would drop slightly because we will not be flying fast enough for any precompression to happen in the intake. Now the compressor will heat the air to 730&amp;nbsp;K, and again adding and burning that kilo of kerosene will heat 1000&amp;nbsp;mol of air to 2213&amp;nbsp;K. Ideally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, the engine control will see that the limit temperatures are not exceeded, but here we can play with the numbers as we like. The exact values will certainly be slightly different (more frictional heating in the compressor, heat loss to the outside, slight drift in specific heat with temperature), but the gist of the explanation is correct.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Explanation in layman's terms&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Burning the fuel-air mixture heats it and makes the gas expand. This happens at nearly constant pressure and in a restricted volume, so the only way to make room for this expansion is for the gas to flow faster. Nearly constant pressure means that the density of the gas must decrease. The density ratio between the heated and the unburnt gas is proportional to its &lt;strong&gt;temperature ratio&lt;/strong&gt;, measured in absolute temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the amount of fuel burnt determines the &lt;strong&gt;absolute&lt;/strong&gt; temperature increase, the &lt;strong&gt;difference&lt;/strong&gt; in degrees between the burnt gas inside the combustion chamber and the unburnt gas at the intake. For a given amount of fuel, the &lt;strong&gt;temperature ratio&lt;/strong&gt; which can be achieved with an absolute temperature increase becomes smaller the higher the temperature of the unburnt gas is. Thus, efficiency decreases with a higher temperature of the intake air.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="998" LastEditDate="2019-02-17T13:06:18.223" LastActivityDate="2019-02-17T13:06:18.223" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="4984" PostTypeId="1" AcceptedAnswerId="4985" CreationDate="2014-05-19T10:04:39.693" Score="2" ViewCount="1219" Body="&lt;p&gt;I tried to google this but could not seem to get a clear answer.  I was wondering because I heard they first mandated all aircraft by some date which was no where near realistic in terms of cost to the airlines.  They therefore either have reconsidered, or will need to reconsider but I am unclear on it all.&lt;/p&gt;&#xA;" OwnerUserId="2213" LastEditorUserId="69" LastEditDate="2014-05-19T12:52:15.730" LastActivityDate="2014-05-19T13:09:47.883" Title="When has China said it will mandate head up displays (HUD)?" Tags="&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4985" PostTypeId="2" ParentId="4984" CreationDate="2014-05-19T10:39:47.073" Score="3" Body="&lt;h2&gt;2025&lt;/h2&gt;&#xA;&lt;p&gt;Sometime in 2012 CAAC are alleged to have suggested 100% of Chinese airlines should have adopted HUDs by 2025.&lt;/p&gt;&#xA;&lt;p&gt;It seems the Rockwell Collins Heads-Up Guidance System (HGS) has been trialled and that HGS equipped aircraft are permitted to land at certain airports in low visibility conditions - lower landing minima for HGS equipped aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Reports mention enhanced vision systems (EFV) and enhanced flight vision systems (AFVS) where the HUD is used to project data, including runway outlines, over the pilot's view of the runway ahead.&lt;/p&gt;&#xA;&lt;p&gt;The CAAC seem to be actively encouraging this, but I don't find the  word mandatory used in this context.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;November 14, &lt;strong&gt;2012&lt;/strong&gt;, 5:07 PM&lt;/p&gt;&#xA;&lt;p&gt;Rockwell Collins China managing director Ron Ho believes business for aircraft head-up displays (HUD) in China will soon be looking up. “We have been working with the Civil Aviation Administration of China (CAAC) for the past 10 years on the HUD project, and now it has reached the stage where &lt;strong&gt;CAAC will require the Chinese airlines to implement the HUDs into their operations&lt;/strong&gt;,” he explained.&lt;/p&gt;&#xA;&lt;p&gt;“This will be done in three phases, I understand,” Ho noted. “During the first phase, 10 percent of all the airlines will be equipped and operating with HUDs. In the [s]econd phase, this will be 50 percent. The third phase will be complete fleet equipage by the year &lt;strong&gt;2025&lt;/strong&gt;.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.ainonline.com/aviation-news/ain-news-live/airshow-china/2012-11-14/chinese-authorities-commit-aircraft-head-display-mandate&quot; rel=&quot;nofollow noreferrer&quot;&gt;AINonline - Chinese Authorities Commit To Aircraft Head-Up Display Mandate&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FAA has also been coordinating with CAAC. In Aug 2012 FAA hosted a Pacific Rim conference in Long Beach CA identifying key technologies, operations and regulations that could be improved with HUD, advanced PFDs and vision systems. Soon after the conference, the CAAC HUD application roadmap appeared. China has without hesitation laid forth a plan to move the country's civil aviation into a 100% HUD compliant operation by 2025.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.propilotmag.com/archives/2013/Jan%2013/A4_HUD_p2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Professional Pilot Magazine - HUD gains favor in Asia Pacific&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Start HGS from 2005&lt;/li&gt;&#xA;&lt;li&gt;End of 2010, 52 B727-NGs&lt;/li&gt;&#xA;&lt;li&gt;... Primary reference for maneuvering ... is natural vision&lt;/li&gt;&#xA;&lt;li&gt;Promote airlines using HUD&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.caac.gov.cn/dev/fbs/xjsyy/201205/P020120611411730706640.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAAC - HUD/EFVS systems in the implement(sic) in China&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-19T13:09:47.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4986" PostTypeId="2" ParentId="4980" CreationDate="2014-05-19T12:30:36.360" Score="33" Body="&lt;p&gt;I've talked to a couple of aerodynamicists, and for small aircraft when you run the numbers the improvement offered by winglets is often less than the drag penalty caused by their weight (which also reduces allowable payload). For larger aircraft that fly long distances, the proportion of the aircraft's weight that is due to the winglets is much smaller than it is for small aircraft, so they don't have this problem and that makes winglets a viable strategy.&lt;/p&gt;&#xA;" OwnerUserId="2376" LastActivityDate="2014-05-19T12:30:36.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="4987" PostTypeId="2" ParentId="4950" CreationDate="2014-05-19T13:14:23.140" Score="0" Body="&lt;p&gt;As noted above, a ground school is not required by the FAA but a sign-off by an instructor is.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know if this is still valid, but a decade ago, one of the big pilot training companies (King? Sporty's? Gleim?) would send you the equivalent of an instructor's endorsement after you took that company's ground school course in the comfort of your own home.  So at least back then, yes, if you sent in the required completed home school tests, you did not need to attend a ground school class.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a good idea?  I vote NO.  the reason is that these courses teach pretty specifically to the tests and little else.  There is a lot of knowledge that you won't get by taking these courses without an instructor even though you can pass the test.  Remember that they are teaching the MINIMUM you need to be safe.  Choose well.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-05-19T13:14:23.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4988" PostTypeId="2" ParentId="4980" CreationDate="2014-05-19T15:30:51.540" Score="23" Body="&lt;p&gt;As others have pointed out winglets don't make much aerodynamic sense for small aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point of a winglet is basically to deflect the wingtip vortex away from the lift-producing part of the wing, granting an increase in &lt;em&gt;effective wing span&lt;/em&gt; without the added form drag of &lt;em&gt;actually&lt;/em&gt; making the wing longer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The winglet itself creates some form drag though, and it adds weight. On most small aircraft the potential improvement in wing efficiency doesn't exceed the  weight and form drag that result from adding the winglet.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What you will find on many small aircraft are Hoerner-style wingtips (either installed at the factory or added later through an STC modification). At lower speeds these have aerodynamic benefits similar to winglets, but without the additional form drag, and usually little or no added weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0ufzx.gif&quot; alt=&quot;Hoerner Wingtip Diagram&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/18LtN.jpg&quot; alt=&quot;Hoerner Wingtip Photo&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="13197" LastEditDate="2016-04-24T21:40:55.500" LastActivityDate="2016-04-24T21:40:55.500" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="4989" PostTypeId="1" CreationDate="2014-05-19T16:14:48.677" Score="11" ViewCount="687" Body="&lt;p&gt;There is some evidence of brain under development in adolescents, those from 13 through as high as 23 or 24, that is linked to judgment, decision making, risk appetite, etc., mostly in an unfavourable way as it relates to properly evaluating a flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See:  &lt;a href=&quot;http://www.nimh.nih.gov/health/publications/the-teen-brain-still-under-construction/index.shtml&quot;&gt;http://www.nimh.nih.gov/health/publications/the-teen-brain-still-under-construction/index.shtml&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this suggest that CFIs training an adolescent should approach the training differently than how they train adults?  Are additional training and scrutiny indicated in order to minimize the effects of an under developed brain in this population group?  Or does doing so somehow cause some level of unwarranted discriminating practices to an adolescent training for his pilot certificates?  &lt;/p&gt;&#xA;" OwnerUserId="838" LastEditorUserId="790" LastEditDate="2014-05-19T19:17:25.377" LastActivityDate="2014-05-19T20:01:02.637" Title="Does training adolescents require a different approach with regard to the level of neurological development?" Tags="&lt;flight-training&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="4990" PostTypeId="2" ParentId="4989" CreationDate="2014-05-19T17:10:18.047" Score="9" Body="&lt;p&gt;No, &lt;a href=&quot;http://www.nimh.nih.gov/health/publications/the-teen-brain-still-under-construction/index.shtml&quot;&gt;that article&lt;/a&gt; doesn't suggest a different training approach with teenagers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it does suggest is that the teenage brain has potentially more &lt;a href=&quot;http://en.wikipedia.org/wiki/Neuroplasticity&quot;&gt;neuroplasticity&lt;/a&gt;, and that &quot;the capacity of a person to learn will never be greater than during adolescence.&quot; It does point out a possible factor to watch out for in young trainees: sleep deprivation, but it doesn't say that the &lt;em&gt;effects&lt;/em&gt; of sleep deprivation are &lt;em&gt;different&lt;/em&gt; than in older trainees, only that they may be more likely to stay up late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article mentions &quot;the importance of creating an environment in which teens can explore and experiment while helping them avoid behavior that is destructive to themselves and others&quot;. Flight instruction seems to me to be exactly such an environment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instructors &lt;em&gt;already&lt;/em&gt; should be adjusting their training approach to the individual. (&lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp975-parti-individual-1069.htm&quot;&gt;Transport Canada - Flight Instructor Guide: Individual Differences&lt;/a&gt;). The advice given is based on symptoms, and there is no indication that a teenage slow learner (for example) should be treated differently than an adult slow learner. There is a column in that guide relating to &quot;immature&quot; trainees, which might apply more frequently to adolescents, but unless a student is showing immaturity, there is no need to treat them so.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastActivityDate="2014-05-19T17:10:18.047" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="4991" PostTypeId="2" ParentId="4989" CreationDate="2014-05-19T20:01:02.637" Score="7" Body="&lt;p&gt;As an instructor at a fairly large university, I see lots of students in the age group you mention. Most of the time, no adjustment to the training course is necessary. There will always be outliers, of course, but in general university students in the 18-23 age group have no problems keeping up with the training curriculum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally, the students that I've personally had the most trouble with aren't the ones that are younger, they're the ones that think they already know what they need to know. Which is just another way of saying that almost anyone with an sincere desire to learn can be taught to become a safe aviator.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-05-19T20:01:02.637" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="4992" PostTypeId="1" AcceptedAnswerId="4997" CreationDate="2014-05-19T22:22:23.007" Score="16" ViewCount="3833" Body="&lt;p&gt;I'm told that swept wings perform better when an aircraft is trying to break the sound barrier.  I was wondering why that would be?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-03-17T17:26:56.133" LastActivityDate="2018-06-18T00:03:42.947" Title="Why are swept wings better for breaking the sound barrier?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;supersonic&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4994" PostTypeId="1" AcceptedAnswerId="4996" CreationDate="2014-05-20T03:14:39.560" Score="17" ViewCount="25875" Body="&lt;p&gt;Delta wings are most commonly seen on military aircraft. I understand that delta wings are ideal for supersonic flight, and provide high maneuverability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having high maneuverability and speed are good characteristics for commercial airliners. But, most of the commercial airliners do not use delta wings (Except for Concorde and Tu-144). &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are there any specific reasons for this?&lt;/li&gt;&#xA;&lt;li&gt;Are there any regulations that prevent using delta wings in commercial airliners?&lt;/li&gt;&#xA;&lt;li&gt;Does it cost more in maintenance?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1337" LastEditorUserId="5517" LastEditDate="2015-10-23T22:00:44.593" LastActivityDate="2017-12-23T18:12:01.893" Title="Why are delta wings not commonly used in commercial airliners?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;wing&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="4995" PostTypeId="1" CreationDate="2014-05-20T04:18:38.403" Score="15" ViewCount="5811" Body="&lt;p&gt;As I understand it, a series of waypoints can be programmed, by a pilot, into one of the autopilots on a Boeing 777. If the autopilot is engaged, the autopilot will cause the aircraft to fly to each waypoint in turn, automatically steering the aircraft as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not clear to me whether the autopilot automatically disengages after reaching the final waypoint or whether it maintains (for example) a magnetic heading and altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens after reaching the last programmed waypoint if the pilot does not intervene?&lt;/p&gt;&#xA;" OwnerUserId="2383" LastEditorUserId="97" LastEditDate="2015-02-20T15:35:16.860" LastActivityDate="2018-02-06T14:33:37.303" Title="What does the Boeing 777 autopilot do after reaching the last programmed waypoint?" Tags="&lt;navigation&gt;&lt;autopilot&gt;&lt;boeing-777&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="4996" PostTypeId="2" ParentId="4994" CreationDate="2014-05-20T04:18:59.563" Score="20" Body="&lt;p&gt;There's a thread on &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/91699/&quot; rel=&quot;noreferrer&quot;&gt;airliners.net&lt;/a&gt; about the same topic.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of the most prominent and useful aspects of the delta wing is the fact that it increases an airplane's critical Mach number (the speed at which some air passing over any part of an aircraft - usually the wing - reaches Mach 1.0).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;By increasing the critical Mach number, it makes supersonic flight much more feasible on delta wings than on conventional wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delta wings are particularly happy even at a high AoA (angle of attack). This is because of the reaction lift generated by the wing, and the vortex created at the leading edge of the wing. Hence, airplanes with delta wings have a much higher tolerance to stalling. This makes it easier to attain higher vertical speed, also known as &quot;rate of climb&quot; safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on the flip side:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of the downsides of deltas is that they create more drag, because of the bigger surface area, but they do have a bigger internal volume (for fuel, for example) which could lead to a smaller fuselage, or more space in the fuselage for other things. Another disadvantage is higher landing and take off speeds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The last point is particularly important. The Concorde's already small number of usable airports was reduced because the runways needed to be long enough to accommodate for the 160 KIAS landing speeds (for comparison, typical turbofan-based airliners lands at 130-140 KIAS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result of the higher takeoff/landing speeds, the  cost of maintenance of vital components such as the brakes and tyres is higher. Moreover, the high landing speeds can even lead to greater stress on the airframe. So, indirectly delta wings do contribute to a higher cost of maintenance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other disadvantages of delta wings I can think of is the lack of a flaps/slats system. Delta wings don't require flaps as they can simply reduce their airspeed by increasing the AoA, but the lack of flaps reduces their subsonic efficiency, and increases the takeoff distance and takeoff velocity. For instance, the Concorde's delta wings produced very little lift during takeoff prior to rotation, necessitating high takeoff speeds of nearly &lt;strong&gt;220 knots&lt;/strong&gt;! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an answer to your second question, I could not find anything about regulations relating to the use of delta wings on airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, delta wings work well for niche purposes such as supersonic aircraft, but their disadvantages and poor operating economics make them impractical for subsonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as you can see here, the now-scrapped Boeing Sonic Cruiser attempted to make the best of both worlds by combining a conventional wing with a delta wing, to form a wide, &quot;cranked-delta&quot; wing design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aEqFj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="504" LastEditDate="2014-06-15T03:29:19.370" LastActivityDate="2014-06-15T03:29:19.370" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="4997" PostTypeId="2" ParentId="4992" CreationDate="2014-05-20T05:28:37.647" Score="14" Body="&lt;p&gt;It's all about the 'effective' Mach number that the wing sees.  In essence, for a swept wing, the Mach number that the wing 'sees' as far as compressibility effects are concerned is the Mach number of the component of the freestream normal to the wing chord:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RFWny.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RFWny.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;https://web.archive.org/web/20140808175751/http://adg.stanford.edu/aa241/drag/images/image61.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;stanford.edu via archive.org&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By sweeping the wing back, you can get closer to the speed of sound without getting supersonic flow over the wing (remember, a wing generates lift by accelerating the air flowing over it, thereby decreasing the pressure - so you'll get supersonic flow over the wing before the freestream is supersonic).  Of course, once you fly supersonic, there's really no getting around having shock waves over the wing - however, you can reduce their strength with wing sweep.&lt;/p&gt;&#xA;" OwnerUserId="2382" LastEditorUserId="14897" LastEditDate="2018-06-18T00:03:42.947" LastActivityDate="2018-06-18T00:03:42.947" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="4999" PostTypeId="2" ParentId="4995" CreationDate="2014-05-20T09:29:21.027" Score="4" Body="&lt;p&gt;The last waypoint is usually at a holding pattern where the plane will fly in circles until the pilot disengages to continue to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example in &lt;a href=&quot;http://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;nofollow&quot;&gt;Helios flight 522&lt;/a&gt; the crew got incapacitated and the plane ended up in a holding pattern for an hour until it ran out of fuel. This was a Boeing 737 but I imagine the 777 having the same.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-05-20T09:29:21.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5000" PostTypeId="2" ParentId="4995" CreationDate="2014-05-20T10:46:18.733" Score="18" Body="&lt;p&gt;The first point I would stress on is that you don't program the autopilot. You program the FMS (Flight Management System), which looks like a very large calculator. In this picture it is the device under then first officer's hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EVWKS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of the PFD (Primary Flight Display) you see the MCP (Mode Control Panel). This is what controls the modes that the autopilot system will follow, here is another image of it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BrJO7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically the entire &lt;em&gt;flight plan&lt;/em&gt; is programmed into the FMC and then during various stages of flight, the autopilot is engaged to help with navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This flight plan includes the departure, enroute waypoints or tracks, and then generally the arrival at the destination; but that is it - it does not include the runway information, etc (as this may be subject to change).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FMC takes this information and other data (weight, fuel, temperature, weather, etc.) to calculate a flight plan which is then displayed; and the pilot will then select and activate a flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most commercial flights however, the flight plan is already loaded in the FMC from the flight operations department and the pilots simply select the predefined flight plan. Punching in a large flight plan takes a significant amount of time so many times this is already downloaded from the flight ops center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At any stage of flight, the autopilot may be armed and engaged to do one of many things - either maintain thurst, or heading, or control the climb/descent; or follow the flight plan. It may also be disarmed during any stage of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is armed and it set to follow the FMC's flight plan; then after the last waypoint it will follow the waypoint heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if the last way point is a holding pattern, it will continue on that pattern. If the last waypoint was a marker it will reach that marker, and then continue at that heading and speed; even though there are no more commands coming to it from the FMC (since its at the end of the programmed flight plan).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that reaching the end of the flight plan from the FMC does not disengage the autopilot; there are many other things that might do that though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the above comes from my time in a 737 and 777 simulator.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-05-20T10:46:18.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5002" PostTypeId="2" ParentId="4994" CreationDate="2014-05-20T12:28:50.733" Score="12" Body="&lt;p&gt;Generally, having as little sweep as possible is the best way to achieve high lift at low drag. Also, regardless of flight speed, a subsonic leading edge gives the best lift/drag ratio. If the sweep of the leading edge is higher than the angle of the Mach cone in supersonic flow, the flow around the leading edge is still like in subsonic flow, and this creates suction, thereby reducing pressure drag. If the cruise speed is Mach 2, the sweep must be bigger than 60 degrees, and with that sweep the lift at slow speed would suffer. Lift goes down with the cosine of the sweep angle at the same angle of attack.&lt;BR&gt;&#xA;Also, at high angle of attack the high sweep angle produces a vortex on the upper surface which reduces pressure (= increases lift) and prevents flow separation (= allows for higher angle of attack). Having more chord inboard helps to utilize this lift better and gives you more space for the wing spar and fuel, even with the low relative thickness that supersonic flow requires.&#xA;&lt;P&gt;&#xA;A subsonic airliner wing needs only moderate sweep to reduce Mach effects even with relatively thick airfoils (14% t/c versus 4% to 6% for supersonic airfoils), which gives you a lot of internal volume for fuel, the wing spar and high-lift devices. Going to a delta wing would help with gust sensitivity in low-level flight (that is why you see delta wings on subsonic aircraft at all), but it would increase the surface area and, consequently, friction drag.&#xA;&lt;P&gt;&#xA;&lt;a href=&quot;http://www.google.de/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0CDAQFjAA&amp;amp;url=http://www.engineerstoolkit.com/Airworthiness%2520Standards%2520%2520FAA%2520FAR%2520Part%252025.pdf&amp;amp;ei=vEx7U7-GFpCA7QaA2IHICQ&amp;amp;usg=AFQjCNEzUCAiTdJ9PxjcOYqOVlCX1xPoPQ&amp;amp;bvm=bv.67229260,d.ZGU&quot;&gt;FAR Part 25&lt;/a&gt; would be the relevant regulation, and it (thankfully) leaves it to the applicant how conformance is achieved. The reason why you see no delta wing on subsonic airliners is purely technical.&#xA;&lt;P&gt;&#xA;If you take all together, the moderately swept-back cantilever wing with high-lift devices is the best way to fly Mach 0.8, and the delta wing is the best for flight at Mach 2.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-05-20T12:43:37.803" LastActivityDate="2014-05-20T12:43:37.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5003" PostTypeId="1" AcceptedAnswerId="5004" CreationDate="2014-05-20T13:24:32.650" Score="17" ViewCount="4203" Body="&lt;p&gt;In &lt;a href=&quot;http://en.wikipedia.org/wiki/Chuck_Yeager&quot;&gt;Chuck Yeager's&lt;/a&gt; autobiography, he went into a little bit of detail as to why the &lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_X-1&quot;&gt;X-1&lt;/a&gt; was able to break the sound barrier safely where as the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot;&gt;P-51D&lt;/a&gt; he flew during WWII could not have safely broken the sound barrier.  He mentioned it had to do with the controls... Something about flow separation, as I recall, and the elevator not working as a result in most aircraft before the X-1.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering if someone could explain this though?  What advances where made during X-1 development that made it stable at Mach 1?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="14897" LastEditDate="2019-08-08T05:37:38.977" LastActivityDate="2019-08-08T05:37:38.977" Title="What control issues did the X-1 have to overcome to achieve supersonic flight?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;supersonic&gt;&lt;bell-x-1&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5004" PostTypeId="2" ParentId="5003" CreationDate="2014-05-20T13:29:15.273" Score="20" Body="&lt;p&gt;The control problems are caused by a shift of the aerodynamic forces. In subsonic flight, they are mostly created in the forward part of the wing (the lift increase with angle of attack works at the quarter chord point of a wing, regardless of sweep), while in supersonic flow they work equally over the full chord. The center of lift in pure supersonic flow is at mid chord, and in reality the aerodynamic center shifts slowly back when the aircraft accelerates through Mach 1 and more of the surface is exposed to supersonic flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the c.g. position is mostly fixed (Concorde pumped fuel between tanks to shift the c.g.), this shift must be compensated with elevator deflection. The elevator must move trailing edge up, which creates a break in the airfoil contour, which in turn creates a heavy shockwave at high subsonic and supersonic flight speed. This shock causes flow separation and can lead to elevator reversal. Only when the fixed part of the horizontal tail can be moved, too, or you have a full-flying tail (the whole stabilizer is moved, not only the rear part of it) to create the needed lift change without a contour break, the aircraft can be trimmed for both subsonic and supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefit of the X-1 was a stabilizer with variable incidence, which the P-51 lacked. Sweep would have helped, too, but was not really necessary.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-23T18:36:47.843" LastActivityDate="2014-10-23T18:36:47.843" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5005" PostTypeId="1" AcceptedAnswerId="5006" CreationDate="2014-05-20T13:31:57.590" Score="5" ViewCount="10457" Body="&lt;p&gt;In the answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight/5004?noredirect=1#5004&quot;&gt;this question&lt;/a&gt; the author mentions the chord of a wing.  What exactly is that, and how is it used in wing design?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-05-20T16:14:46.483" Title="What is the chord of a wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5006" PostTypeId="2" ParentId="5005" CreationDate="2014-05-20T14:00:22.017" Score="8" Body="&lt;p&gt;the &lt;a href=&quot;http://en.wikipedia.org/wiki/Chord_%28aircraft%29&quot; rel=&quot;noreferrer&quot;&gt;Chord&lt;/a&gt; is the line stretching from the leading edge of the wing to the trailing edge parallel to the centerline.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/JnG91.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JnG91m.png&quot; alt=&quot;Chord diagram from the Pilot&amp;#39;s Handbook of Aeronautical Knowledge&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are different variations to describe the chord of the whole wing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The &lt;strong&gt;Standard Mean Chord&lt;/strong&gt;&lt;br&gt;&#xA;Defined as $\frac S b$ with $S$ the surface area and $b$ the span of the wing. This is not used in aerodynamics.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The &lt;strong&gt;Mean Aerodynamic Chord&lt;/strong&gt;&lt;br&gt;&#xA;Defined as $\frac2 S \int_0^{\frac b 2} c(y)^2 dy$ with $y$ the coordinate along the wing and $c(y)$ the chord at $y$.&lt;br&gt;&#xA;For swept or delta wings this gives the equivalent chord for a rectangular wing, and is important for placing the Center of Gravity for stability.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="609" LastEditorUserId="64" LastEditDate="2014-05-20T16:14:46.483" LastActivityDate="2014-05-20T16:14:46.483" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5007" PostTypeId="2" ParentId="4994" CreationDate="2014-05-20T15:12:12.407" Score="8" Body="&lt;p&gt;The primary design driver of a commercial airliner wing is &lt;em&gt;efficiency&lt;/em&gt;, and second to that is speed. While delta wings are good at high speeds, they are not very efficient. Also, while an airliner should certainly be maneuverable, they do not need to &quot;do a barrel roll&quot; or make 9G turns light a fighter jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was mentioned that delta wings have a large surface area. This helps to distribute the weight of the aircraft more, which leads to a low &lt;a href=&quot;http://en.wikipedia.org/wiki/Wing_loading&quot;&gt;wing loading&lt;/a&gt;. This is one factor in the higher maneuverability of the delta wing. Compare the wing loading of the F-15 at 73.1 lb/ft&lt;sup&gt;2&lt;/sup&gt; with the wing loading of a 737-800 at 98.7 lb/ft&lt;sup&gt;2&lt;/sup&gt;. The delta wing allows the F-15 to have lower wing loading and thus much more maneuverability. The design also keeps this large wing area to a low wingspan, which means that high-G maneuvers cause lower stress on the wing. Airliners have plenty of maneuverability with their current configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This large area and high speed performance is at the expense of efficiency. The lift to drag ratio (L/D) of an F-15 is around 10, while commercial jets get over 16 (see &lt;a href=&quot;http://books.google.com/books?id=NeHoahlhCGMC&amp;amp;lpg=PA86&amp;amp;ots=DRa4SHq3E2&amp;amp;dq=a320%20l/d%20ratio&amp;amp;pg=PA86#v=onepage&amp;amp;q=a320%20l/d%20ratio&amp;amp;f=false&quot;&gt;this table&lt;/a&gt; for some examples). This shows the huge advantage that a non-delta wing has at subsonic speeds. Modern aerodynamics have allowed commercial airliners to reach high subsonic speeds (Mach 0.8-0.9) while remaining very efficient. While fighter jets use aerial refueling to compensate for burning more fuel, this would be a bit unrealistic for a commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low speed performance is also a factor. Both wings are able to use flaps and slats, but landing speeds for fighter jets are generally higher than commercial aircraft. Being better suited for high-speed flight, delta wings are less effective at low speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as maintenance is concerned, there are fewer differences. Since the wingspan would be lower, this would put less load on the wings. Reducing the load could be turned into a maintenance advantage, but there are many more factors in determining maintenance cost.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-05-21T16:40:47.980" LastActivityDate="2014-05-21T16:40:47.980" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5008" PostTypeId="2" ParentId="5003" CreationDate="2014-05-20T15:30:06.337" Score="11" Body="&lt;p&gt;The phenomenon you are describing is called &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Mach_tuck&quot; rel=&quot;noreferrer&quot;&gt;Mach tuck&lt;/a&gt;.&quot; As Peter described, the location of the lift forces changes, which can be more than the elevator can compensate for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also another factor at work. This image shows what is happening on a wing or tail surface near supersonic speeds. At the higher speeds, a flow separation is shown. This means that the flow is no longer &quot;sticking&quot; to the surface, instead creating turbulence in that area. This flow separation occurs at the trailing edge, exactly where the control surfaces tend to be. This means that instead of deflecting into smooth flow, they enter turbulence. This can cause buffeting in the controls, and makes the control surfaces much less effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution to this problem was to move the entire tail surface instead of just a trailing edge portion. Since this surface now acts as both the horizontal stabilizer and the elevator, it is called a &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Stabilator&quot; rel=&quot;noreferrer&quot;&gt;stabilator&lt;/a&gt;.&quot; You will notice this feature on most supersonic fighter jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SJGLQ.jpg&quot; alt=&quot;Supersonic flow on airfoil&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-20T15:30:06.337" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5009" PostTypeId="1" AcceptedAnswerId="5010" CreationDate="2014-05-20T16:17:49.550" Score="14" ViewCount="9078" Body="&lt;p&gt;Since pitot static systems are open the outside, how does the system remain clear of water or other contaminants?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-20T16:48:01.577" Title="How is the pitot system drained?" Tags="&lt;pitot-static&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5010" PostTypeId="2" ParentId="5009" CreationDate="2014-05-20T16:48:01.577" Score="14" Body="&lt;p&gt;Though it's often omitted from diagrams, most pitot tubes have one or more drain holes connected to the pressure chamber, and are essentially &quot;self-draining&quot; (water doesn't make it into the lines):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2hC7t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2hC7tm.jpg&quot; alt=&quot;Piper pitot blade - Drain on bottom&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/fVSDM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fVSDMm.jpg&quot; alt=&quot;Dynon pitot tube drain holes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to drains on the pitot tube itself some aircraft have separate &quot;drip chambers&quot; and drains for the pitot (and occasionally static) system to remove condensation or rain that got past the drains (marked as &lt;code&gt;2&lt;/code&gt; in the photo below):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZeN08.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZeN08.jpg&quot; alt=&quot;PA-28 pitot/static drains&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding other contaminants, at altitude the air is generally pretty clean.&lt;br&gt;&#xA;The biggest problem you'll have with contaminants in the pitot tube is usually bugs (either building a nest in the opening, or smacking into it in flight). Pitot covers can be used on the ground to prevent this (and they're also used when washing or painting aircraft to prevent water or paint from getting into the system). Often some tape serves the same purpose - but you need to be sure to remove the tape or cover before flying.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/imdrz.jpg&quot; alt=&quot;Someone is having a bad day...&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-20T16:48:01.577" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="5011" PostTypeId="1" AcceptedAnswerId="5012" CreationDate="2014-05-20T18:53:02.150" Score="18" ViewCount="3930" Body="&lt;p&gt;Have pilots ever encountered a UFO? What guidelines, if any, are in place for times when this happens?&lt;/p&gt;&#xA;" OwnerUserId="2390" LastEditorUserId="1696" LastEditDate="2019-09-13T15:19:53.060" LastActivityDate="2019-09-13T15:19:53.060" Title="Have pilots encountered a UFO, and what to do if you have?" Tags="&lt;faa-regulations&gt;&lt;pilots&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="5012" PostTypeId="2" ParentId="5011" CreationDate="2014-05-20T19:00:48.857" Score="37" Body="&lt;p&gt;Pilots do encounter UFOs all the time. I just want to emphasize that UFO means &quot;Unidentified Flying Object&quot; - something which is flying, and which the pilot cannot identify. It does not mean an alien craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The guidelines for pilots are as follows (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0706.html&quot;&gt;AIM 7-6-4&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;7-6-4. Unidentified Flying Object (UFO) Reports&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Persons wanting to report UFO/unexplained phenomena activity should contact a UFO/unexplained phenomena reporting data collection center, such as Bigelow Aerospace Advanced Space Studies (BAASS) (voice: 1-877-979-7444 or e-mail: Reporting@baass.org), the National UFO Reporting Center, etc.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; If concern is expressed that life or property might be endangered, report the activity to the local law enforcement department.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Air traffic controllers have the following guidance under &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0908.html&quot;&gt;FAA Order 7110.65 section 9-8-1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;9-8-1. GENERAL&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Persons wanting to report UFO/unexplained phenomena activity should contact a UFO/ unexplained phenomena reporting data collection center, such  the National UFO Reporting Center, etc.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; If concern is expressed that life or property might be endangered, report the activity to the local law enforcement department.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The question &quot;Was it of the E.T. kind&quot; is beyond the scope of this site. This subject is, let's just say, suitably covered by other sites on the Internet at large.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One notable example of a UFO report is the &lt;a href=&quot;http://en.wikipedia.org/wiki/2006_O%27Hare_International_Airport_UFO_sighting&quot;&gt;2006 O'Hare UFO sighting&lt;/a&gt;. For other examples, a Google search for &quot;&lt;a href=&quot;https://www.google.com/#q=pilot+UFO+anecdotes&quot;&gt;pilot UFO anecdotes&lt;/a&gt;&quot; offers some decent results. &quot;&lt;a href=&quot;https://www.google.com/#q=atc+ufo+report&quot;&gt;ATC UFO report&lt;/a&gt;&quot; even links to some recordings of pilot UFO reports to ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some objects commonly reported (genuinely) as UFOs are spacecraft, fast or high-flying military aircraft like the U-2 or the SR-71 when it was in service, rocket launches, weather balloons, kites, errant helium balloons from kids' birthday parties, flocks of birds, con trails, and lightning storms. Any of these and more can easily look, under the right circumstances, to a pilot like a &quot;UFO.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest experience I've had in my flying history to a &quot;UFO&quot; happened at night, during a landing approach in the midwest U.S. I was on a downwind leg when a very bright light appeared above me in the center of the windscreen, and rapidly moved downward toward the horizon. It scared me half to death; my instinctual thought was that it was the landing light of another plane descending on top of me. It turned out to be a meteorite. It only took me a second or two to figure it out, but boy did it get my adrenaline up! There was no need to report it though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Culturally, pilots are generally apprehensive about reporting UFOs, out of fear of sounding like a lunatic or unhinged conspiracy theorist and being laughed at. Nonetheless, reports are not uncommon.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-05-21T15:08:29.583" LastActivityDate="2014-05-21T15:08:29.583" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5015" PostTypeId="1" AcceptedAnswerId="5016" CreationDate="2014-05-21T02:15:27.313" Score="12" ViewCount="8775" Body="&lt;p&gt;Why is Thunderbird 5's number written upside down?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i59.photobucket.com/albums/g293/trainshooter/Thunderbird5.jpg&quot; alt=&quot;Thunderbird 5&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.070" LastActivityDate="2020-05-13T17:19:19.377" Title="Why is Thunderbird 5's number upside down?" Tags="&lt;airshow&gt;&lt;thunderbirds&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5016" PostTypeId="2" ParentId="5015" CreationDate="2014-05-21T02:21:25.760" Score="11" Body="&lt;p&gt;This is because Thunderbird 5 is the opposing solo, and spends almost all of its time inverted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4uFNy.jpg&quot; alt=&quot;thunderbird5&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/mFdLb.jpg&quot; alt=&quot;thunderbird5&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently though, this plane's number was not always painted upside down:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/f/ff/USAF_Thunderbirds_-_T-38s_1980.jpg&quot; alt=&quot;t38s&quot;&gt;&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/c/c8/USAF_Thunderbirds_-_F-4s_-_1972.jpg&quot; alt=&quot;f4s&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just guesswork on my part, but maybe the Thunderbirds did not fly inverted maneuvers before the F-16s?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="1467" LastEditDate="2020-05-13T17:19:19.377" LastActivityDate="2020-05-13T17:19:19.377" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="5017" PostTypeId="2" ParentId="5015" CreationDate="2014-05-21T02:23:59.563" Score="4" Body="&lt;p&gt;When the Thunderbird's fly the reflection pattern, one plane will be right side up flying level. Number 5 will be upside down and below the first one. They are like reflections in a mirror, bottom to bottom. Number 5's engine number is written upside down, so that it can be read correctly. If they fly the calypso pattern, where one plane is flying right side up and the second will be above it, upside down, the upside down plane will always be number 5.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-05-21T02:23:59.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5018" PostTypeId="1" CreationDate="2014-05-21T02:58:46.457" Score="20" ViewCount="25574" Body="&lt;p&gt;On a commercial airliner, what is the purpose of the flaps? I understand that depending on which direction they move in, they can be used to decrease airspeed, but I don't know when flaps are used. Are flaps used before takeoff, after takeoff and on approach?&lt;/p&gt;&#xA;" OwnerUserId="2390" LastEditorUserId="3504" LastEditDate="2014-10-13T16:02:44.513" LastActivityDate="2019-03-02T01:17:11.317" Title="Why and when to use flaps?" Tags="&lt;aerodynamics&gt;&lt;flight-training&gt;&lt;pilots&gt;&lt;flaps&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5019" PostTypeId="1" AcceptedAnswerId="26082" CreationDate="2014-05-21T05:44:47.870" Score="16" ViewCount="4510" Body="&lt;p&gt;The Wikipedia entry for the A380 &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;gives the maximum range at design load as 15,700 km&lt;/a&gt;. The equivalent entry for a Boeing 747-400 gives around 14,000 km but &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_distance_record#Commercial_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;distances of 18,000 km have been performed in demonstrations&lt;/a&gt;. So I infer the ferry range for the A380 would be even higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it specified anywhere? Has a flight by an A380 in excess of 15,700 km been performed to date? Could it fly between any two suitable airports on Earth, i.e., farther than 20,038 km?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="14897" LastEditDate="2017-02-15T21:29:27.250" LastActivityDate="2017-02-15T21:29:27.250" Title="What is the ferry range of an A380?" Tags="&lt;aircraft-performance&gt;&lt;airbus-a380&gt;&lt;range&gt;&lt;ferry-flight&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5020" PostTypeId="2" ParentId="5018" CreationDate="2014-05-21T09:37:41.447" Score="19" Body="&lt;p&gt;Flaps &lt;em&gt;increase &lt;a href=&quot;http://www.langleyflyingschool.com/Pages/CPGS%204%20Aerodynamics%20and%20Theory%20of%20Flight%20Part%201.html&quot; rel=&quot;noreferrer&quot;&gt;lift and drag&lt;/a&gt;&lt;/em&gt; by changing the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfoil&quot; rel=&quot;noreferrer&quot;&gt;camber&lt;/a&gt; of the airfoil, and &lt;em&gt;allow lower airspeeds&lt;/em&gt;. There is also an effect of shifting the &lt;a href=&quot;http://www.grc.nasa.gov/WWW/K-12/airplane/cp.html&quot; rel=&quot;noreferrer&quot;&gt;center of pressure&lt;/a&gt; (C of P) aft. There may be an immediate decrease in airspeed due to the increase in drag (see the Wikipedia article linked below) until the aircraft regains stability by nosing down. There are some incorrect discussions online, such as one &lt;a href=&quot;http://answersforpilots.com/1/what-is-the-purpose-of-flaps&quot; rel=&quot;noreferrer&quot;&gt;answer on this page&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps are frequently used when landing because they lower the stall speed and increase the angle of descent. The pilot will also have better visibility due to the lower nose position caused by the aft C of P.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps increase both lift and induced drag, but a small amount (e.g. 10 degrees) of take-off flaps may provide enough extra lift to allow the plane to become airborne sooner, without a large increase in drag, allowing for a shorter takeoff roll. Whether takeoff flaps can be used is declared in each aircraft's standard operating procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found these resources that I like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.askacfi.com/5494/how-to-explain-flaps-to-a-student-pilot.htm&quot; rel=&quot;noreferrer&quot;&gt;How to explain flaps to a Student Pilot?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flap_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;Flap (aeronautics) on Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2394" LastEditorUserId="2394" LastEditDate="2015-10-13T12:50:04.440" LastActivityDate="2015-10-13T12:50:04.440" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="5021" PostTypeId="1" AcceptedAnswerId="5022" CreationDate="2014-05-21T20:05:53.427" Score="9" ViewCount="24647" Body="&lt;p&gt;I am looking for some general advice - this is specific to the UK but may be similar else where.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know it is possible to hire a private aircraft, I see comments like this &lt;a href=&quot;http://flyasg.co.uk/aircraft-hire/4570205128&quot; rel=&quot;noreferrer&quot;&gt;on club/rental sites&lt;/a&gt; all the time:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fly ASG members can experience affordable personal air travel for the Channel Islands, France and beyond. Fly ASG offers their services of non chartered aircraft rental to engage customers with a new streamlined approach to business and leisure travel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many sites mention the brakes on - brakes off fee per hour, but say you took that trip to the Channel Islands, France, or beyond: how do these companies usually charge for the bit where you will presumably be parked while you work on your sand castles at the beach for the day? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to be clear I'm not asking about airport parking etc. but how the owner of the aircraft will charge when it is not flying.&lt;/p&gt;&#xA;" OwnerUserId="2398" LastEditorUserId="64" LastEditDate="2014-05-23T20:45:04.470" LastActivityDate="2017-07-16T17:16:48.390" Title="How do aircraft rental companies charge while the plane is not flying?" Tags="&lt;general-aviation&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5022" PostTypeId="2" ParentId="5021" CreationDate="2014-05-21T21:44:42.390" Score="12" Body="&lt;p&gt;Flying clubs and aircraft renters generally only charge for the time the plane is actually in use. In the U.S. at least, this is commonly measured using the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hobbs_meter&quot;&gt;Hobbs time&lt;/a&gt; (actual clock time used, triggered by oil pressure or some other indicator that the plane is &quot;in use&quot;), or by &lt;a href=&quot;http://en.wikipedia.org/wiki/Tach_Timer&quot;&gt;Tach time&lt;/a&gt;, which is a bit trickier but can very roughly be thought of as the amount of wear you've put on the engine. (Strictly speaking it's a count of the number of engine revolutions, converted to &quot;hours at cruise RPM&quot;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For overnight or longer trips, it's common to find a &lt;em&gt;minimum hourly usage per day&lt;/em&gt;. For example, if you take a plane on a 3-day trip, and your club/owner requires 2 hours/day, you will be paying for 2 x 3 = 6 hours of Tach / Hobbs / whatever time, even if you didn't actually use the plane that much. You'll pay for the higher of your &lt;em&gt;actual&lt;/em&gt; usage or your &lt;em&gt;minimum usage per day&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's extremely rare in the U.S., but not unheard-of, to encounter an extra fixed fee per day for taking the airplane for more than one day. (I've never personally encountered a fixed fee like this.) I'm not sure if things are different in the U.K.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hourly rates can also either be &quot;wet&quot; (the rate includes fuel: any amount you pay for fuel will be deducted from your rental fee when you return) or &quot;dry&quot; (the rate includes the airplane only and you must pay for fuel). &quot;Dry&quot; rentals may or may not also require you to pay for oil or other consumables used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is general information. Of course, if your question is specifically about Fly ASG's policies and fee scales, your best bet is to contact them directly. I know nothing about them.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-05-21T21:56:35.743" LastActivityDate="2014-05-21T21:56:35.743" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="5023" PostTypeId="1" AcceptedAnswerId="5036" CreationDate="2014-05-21T22:09:27.453" Score="8" ViewCount="517" Body="&lt;p&gt;I'm currently working through my collection of Spike and Suzy albums, and in the album I'm currently reading, one of the main characters crashes with a hot air balloon near the wreckage of a hang glider without sail cloth. The main character, who is usually characterized as a somewhat smart man with skill in engineering, tore a large section from the balloon cloth, tied it to the hang glider wreckage and managed to make a functional hang glider that could even make a reasonable ascent in the Alps, near the Mont Blanc and catch up with his friends who were in other hot air balloons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hang glider looked like this (I couldn't find a bigger image, sorry):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/S1jrV.gif&quot; alt=&quot;makeshift hang glider&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How would this type of makeshift hang glider work IRL? even though hang gliders and hot air balloons are made from the same kind of fabric (ripstop nylon), wouldn't the holes between the frame and the cloth totally ruin the thing? &lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="1467" LastEditDate="2016-05-25T10:37:43.883" LastActivityDate="2016-05-25T10:37:43.883" Title="can the wreckages of a hot air balloon and a hang glider be salvaged for a working hang glider?" Tags="&lt;unpowered&gt;&lt;balloon&gt;&lt;hang-glider&gt;&lt;amateur-built&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5024" PostTypeId="2" ParentId="4962" CreationDate="2014-05-21T23:41:25.810" Score="-1" Body="&lt;p&gt;I havn't worked with it yet, but maybe &lt;a href=&quot;http://jsbsim.sourceforge.net/&quot; rel=&quot;nofollow&quot;&gt;this utility&lt;/a&gt; can help you.&lt;/p&gt;&#xA;" OwnerUserId="2399" LastEditorUserId="65" LastEditDate="2015-03-30T13:24:25.827" LastActivityDate="2015-03-30T13:24:25.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5026" PostTypeId="1" AcceptedAnswerId="5030" CreationDate="2014-05-22T04:45:18.403" Score="58" ViewCount="33387" Body="&lt;p&gt;How can a fighter aircraft involved in a face-off detect a missile lock from a trailing aircraft so that it can make evasive maneuvers?&lt;/p&gt;&#xA;" OwnerUserId="2344" LastEditorUserId="1696" LastEditDate="2018-04-30T01:43:45.013" LastActivityDate="2019-11-04T23:12:44.503" Title="How is a missile lock detected?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;radar&gt;&lt;missile-lock&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="5027" PostTypeId="5" CreationDate="2014-05-22T06:10:52.013" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-05-22T06:10:52.013" LastActivityDate="2014-05-22T06:10:52.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5028" PostTypeId="4" CreationDate="2014-05-22T06:10:52.013" Score="0" Body="Use for questions regarding gliders where the pilot rides in a harness hanging off the airframe, usually controlled using a weight-shift control system. For weight-shift powered aircraft, use the [weight-shift-control] tag instead." OwnerUserId="247" LastEditorUserId="72" LastEditDate="2014-05-22T11:22:56.997" LastActivityDate="2014-05-22T11:22:56.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5029" PostTypeId="2" ParentId="5026" CreationDate="2014-05-22T08:29:48.827" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The subject of a radar lock-on may become aware of the fact that it is&#xA;  being actively targeted by virtue of the electro-magnetic emissions of&#xA;  the tracking system, notably the illuminator. This condition will&#xA;  present a heightened threat to the target, as it indicates that a&#xA;  missile may be about to be fired at it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Missile_lock-on#Detection_by_the_target&quot;&gt;http://en.wikipedia.org/wiki/Missile_lock-on#Detection_by_the_target&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2400" LastActivityDate="2014-05-22T08:29:48.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5030" PostTypeId="2" ParentId="5026" CreationDate="2014-05-22T11:34:39.453" Score="48" Body="&lt;p&gt;To add some data to Matthew's answer: &lt;br/&gt;&#xA;Anti aircraft missiles come in basically 4 types (some others have been tried but aren't in common use).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Active radar homing&lt;/li&gt;&#xA;&lt;li&gt;Passive radar homing&lt;/li&gt;&#xA;&lt;li&gt;Infrared homing&lt;/li&gt;&#xA;&lt;li&gt;Laser guided&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Active radar homing has a radar in the missile sending out signals. Those signals can be detected and classified by the target aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passive radar homing has a receiver in the missile reacting to specific signals bounced off of the target by the launching system. These too can be detected and classified by the target aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Infrared missiles are completely passive and can't be detected this way.&lt;br/&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Laser guided missiles are like passive radar homing missiles, except they react to reflections of a laser beam rather than a radar signal. These too can of course be detected and classified with appropriate sensors.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There have been some attempts at detecting missiles by their own infrared signature, typically their engine exhaust. But this is problematic because most of that is of course blocked from the missile's target by the missile body, and also many missiles will spend a lot of their flight towards the target in an unpowered glide state, thus not having a hot engine exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other systems generally can't be detected by the target either. Think optical guidance using a radio link with the missile (while you might be able to detect the link, you can't readily know what it's doing or that you're the target if you do recognise it as a missile guidance link).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Optical guidance using control wires is not generally used with anti-aircraft missiles, but sometimes anti-tank missiles using these systems are used against slow flying aircraft. These are utterly impossible to detect.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="900" LastEditDate="2014-05-22T14:05:48.637" LastActivityDate="2014-05-22T14:05:48.637" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="5031" PostTypeId="1" CreationDate="2014-05-22T12:21:55.750" Score="10" ViewCount="5722" Body="&lt;p&gt;I understand that aircraft are pressurized by pushing air into the cabin using the engines, and using a valve to let the air escape at a controllable rate thus achieving the desired pressure differential. However, when air is compressed, it heats up and if I understand correctly, all pressurized aircraft have air conditioning units to keep the temperatures at a reasonable level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all air conditioning units were to fail, how hot would the air being shoved into the cabin actually be? If this depends on aircraft and or engine type, any example as a ballpark figure would be appreciated.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2016-10-05T10:46:16.353" Title="How hot would pressurized air get if the air conditioning failed?" Tags="&lt;cabin-pressure&gt;&lt;temperature&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5032" PostTypeId="1" CreationDate="2014-05-22T12:33:10.527" Score="8" ViewCount="1580" Body="&lt;p&gt;I would like to learn more about how the Air Traffic Control system works - are there any resources available which describe the system that would be suitable for a beginner or student?&lt;/p&gt;&#xA;" OwnerUserId="2404" LastEditorUserId="64" LastEditDate="2014-05-22T13:29:36.333" LastActivityDate="2015-12-01T00:59:45.073" Title="Where can I find Air Traffic Control information material suitable for beginners and students?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5033" PostTypeId="2" ParentId="5031" CreationDate="2014-05-22T12:44:23.087" Score="7" Body="&lt;p&gt;The air conditioning is in a so called &quot;air cycle machine&quot; (ACM). If it fails, the air will not be compressed (done in the same machine). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature goes up and down as the air passes through the machine's heat exchangers, compressors and turbines, reaching 250$^\circ$C at peak. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_cycle_machine#Technical_details&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia article&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/wYNyt.gif&quot; alt=&quot;http://www.thisisecs.com&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.thisisecs.com&quot; rel=&quot;noreferrer&quot;&gt;Image from ECS&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-05-22T12:50:21.387" LastActivityDate="2014-05-22T12:50:21.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5034" PostTypeId="2" ParentId="5031" CreationDate="2014-05-22T13:13:19.000" Score="6" Body="&lt;p&gt;The exact values depend on the specific aircraft and engine setup, of course, but I'll talk about a 767-300ER with P&amp;amp;W4000 engines at cruise altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing to take in to account is Gay-Lussac's law&#xA;\begin{equation}&#xA;\frac{P_1}{T_1}=\frac{P_2}{T_2}&#xA;\end{equation}&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure outside the aircraft @ cruise is around -70°F (~216 K) and 2.9 psi (~20 kPa). The pressure inside the aircraft (we'll talk about the compressing stage in a moment) is around 11.5 psi (~79.3 kPa).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;\begin{equation}&#xA;\frac{20\ kPa}{216\ K}=\frac{79.3\ kPa}{T_2}&#xA;\end{equation}&#xA;\begin{equation}&#xA;T_2 = 856.44\ K (1082°F)&#xA;\end{equation}&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, its a bit more complicated than this, because this assumes that the volume of air is constant, which in this case it is not. In the low-stage compressor, the air is compressed to 30 psi (~206.8 kPa) and 400°F (~477.6 K). That is what is piped through the bleed valve and into the air conditioning units and is most likely what the temperature of the air would be if the bleed valve was closed and the air conditioning units were disabled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cabinfiles.com/?CFrequest=file;03032001100119&quot; rel=&quot;noreferrer&quot;&gt;Source (PDF Warning)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2292" LastEditorUserId="2292" LastEditDate="2014-05-22T13:55:35.903" LastActivityDate="2014-05-22T13:55:35.903" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5035" PostTypeId="2" ParentId="5032" CreationDate="2014-05-22T13:27:59.487" Score="5" Body="&lt;p&gt;The first two places I would start would be &lt;a href=&quot;http://www.faa.gov/air_traffic/&quot;&gt;the FAA's Air Traffic Control landing page&lt;/a&gt;, and &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/AIM/TOC.html#Chapter%204.%E2%80%82Air%20Traffic%20Control&quot;&gt;Chapter 4 of the Aeronautical Information Manual&lt;/a&gt; which deals with air traffic control (and is generally the level of information student pilots are expected to be familiar with).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While these references are both for the US/FAA air traffic control system there are strong similarities among the systems in most countries (the ones with the greatest variation would be countries where the military handles air traffic control).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you're looking for more advanced information &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot;&gt;pretty much all of the operational and training manuals the FAA uses are available to the public&lt;/a&gt;.  These are likely of more interest to someone studying to become an air traffic controller - the information in them is substantially more technical and &quot;job-oriented&quot; than what's presented in the resources above.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-22T13:27:59.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5036" PostTypeId="2" ParentId="5023" CreationDate="2014-05-22T13:52:39.680" Score="11" Body="&lt;p&gt;To expand a bit on what @ratchetfreak said in a comment...  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The leading edge on that glider is not secured properly.  It would need to go around the bar all the way along the leading edge of the wing, otherwise the holes would make it so the airfoil doesn't function.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it is right now, the air would hit those gaps and make the cloth flutter, which would break up the airflow over the glider itself.  Thus you'd just have turbulence over the wing, which would make the wing stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, yeah, in a nutshell, that wouldn't work as a glider as pictured above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, if he had found some string or wire from the wrecked balloon and properly secured some of the Hot Air Balloon cloth to the frame...  There's no reason it shouldn't work.  Hot Air Balloons are made out of fabric that is very very similar to what hang gliders are made from.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-05-22T13:52:39.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5037" PostTypeId="2" ParentId="5026" CreationDate="2014-05-22T15:50:30.690" Score="27" Body="&lt;p&gt;A general search radar, because it has to search a much larger portion of the area around the plane, can only scan so many times a second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When that radar finds a target, and the pilot commands the system to lock onto the target, it enables a different radar system, that searches a much smaller portion of the area around the plane where the target is known to be.  This gives not only greater resolution on the target, but it can scan it much faster because it's only scanning a small portion of the area around the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Targeted missiles also only scan a small portion ahead of them, and do so very quickly so they can react quickly to changes in target vector and position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most &quot;missile lock indicators&quot; simply listen to how frequently a radar scan takes place, and when it starts happening very quickly it indicates that the faster, more focused radar has found them and is considered locked on, or that a missile with a fast, focused radar has found them and is locked on.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2014-05-22T15:50:30.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5038" PostTypeId="1" AcceptedAnswerId="5039" CreationDate="2014-05-22T18:06:14.733" Score="3" ViewCount="2268" Body="&lt;p&gt;I heard someone talking about a position in the U.S. Air Force called an Air Battle Manager or ABM. What does a person in this position do?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-05-22T18:54:36.893" Title="What does an Air Battle Manager do?" Tags="&lt;military&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5039" PostTypeId="2" ParentId="5038" CreationDate="2014-05-22T18:25:55.800" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_battle_manager&quot; rel=&quot;nofollow&quot;&gt;Air battle manager&lt;/a&gt; has the following duties:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Plan and execute theater air operations&lt;/li&gt;&#xA;&lt;li&gt;Analyze national defense strategy&lt;/li&gt;&#xA;&lt;li&gt;Develop and conduct flying and simulation exercises&lt;/li&gt;&#xA;&lt;li&gt;Conduct, manage, evaluate and improve unit training and readiness&lt;/li&gt;&#xA;&lt;li&gt;Create operational policies&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Further information can be found at &lt;a href=&quot;http://www.airforce.com/careers/detail/air-battle-manager-abm/&quot; rel=&quot;nofollow&quot;&gt;AirForce's website&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In USAirForce, there are seven categories of aeronautical ratings. They are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot&lt;/li&gt;&#xA;&lt;li&gt;Navigator&lt;/li&gt;&#xA;&lt;li&gt;Combat Systems Officer (CSO)&lt;/li&gt;&#xA;&lt;li&gt;Air Battle Manager (ABM)&lt;/li&gt;&#xA;&lt;li&gt;RPA Pilot&lt;/li&gt;&#xA;&lt;li&gt;Observer&lt;/li&gt;&#xA;&lt;li&gt;Flight Surgeon&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For further reading about these ratings, read &lt;a href=&quot;http://en.wikipedia.org/wiki/U.S._Air_Force_aeronautical_rating&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-05-22T18:54:36.893" LastActivityDate="2014-05-22T18:54:36.893" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5041" PostTypeId="1" AcceptedAnswerId="5045" CreationDate="2014-05-23T01:20:18.980" Score="8" ViewCount="2171" Body="&lt;p&gt;I'm wondering about how much CVR and FDR data an A320 (for example) would produce and at what intervals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that there are 4 or 5 voice channel and several sensor data things. I'm trying to get some data on commercial jets. Is there any place I could get some data on this?&lt;/p&gt;&#xA;" OwnerUserId="2416" LastEditorUserId="1467" LastEditDate="2014-05-23T06:23:35.813" LastActivityDate="2015-04-07T16:43:34.400" Title="How much data do FDR and CVR generate on commercial jets?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5042" PostTypeId="2" ParentId="5041" CreationDate="2014-05-23T04:52:04.843" Score="1" Body="&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_recorder&quot; rel=&quot;nofollow&quot;&gt;Wikipedia: Flight recorder&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An FAA-standard flight data recorder will record a minimum of 88 parameters, sampled several times per second.  An FAA-standard cockpit voice recorder will record four channels of audio.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-05-23T04:52:04.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5045" PostTypeId="2" ParentId="5041" CreationDate="2014-05-23T16:29:20.177" Score="6" Body="&lt;p&gt;The requirements for Flight Data Recorders (FDRs) on airliners like the A320 is in 14 CFR 121. For a good summary of the requirements for flight recorders in various types of aircraft, see the &lt;a href=&quot;http://www.ntsb.gov/doclib/manuals/FDR_Handbook.pdf&quot; rel=&quot;nofollow&quot;&gt;NTSB FDR Handbook&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the certification date of the aircraft (14 CFR 121.343), the FDR must record between 6 and 17 parameters. Since engine parameters are included, this could be up to 23 different parameters on 4-engine aircraft. Newer Digital FDRs (DFDRs) must record at least 88 items (14 CFR 121.344). Some of these parameters are conditional, and some require multiple parameters, so the total will probably be more than 88 parameters. The NTSB report on the &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf&quot; rel=&quot;nofollow&quot;&gt;US Airways 1549 accident&lt;/a&gt; notes that the FDR recorded 178 parameters during the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Data_Recorder_%28FDR%29&quot; rel=&quot;nofollow&quot;&gt;this page&lt;/a&gt;, tape-based DFDRs can record at 64 12-bit data words per second. Newer DFDRs using solid state recording can store up to 256 12-bit data words per second. This 256 words per second is also specified in the information on &lt;a href=&quot;http://visualjournalism.com/wp-content/uploads/Flight_Data_Recorder_%28SSFDR%29.pdf&quot; rel=&quot;nofollow&quot;&gt;this FDR&lt;/a&gt;. It says it can record &gt;100 hours at 64 words/second, which translates to about 35 MB total. The parameters are per DO-160C standard, which you have to pay to access.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accident reports will generally include readouts from relevant parameters, to give an idea of the items that are recorded. There is a table &lt;a href=&quot;http://www.bea.aero/etudes/use.of.fdr/use.of.fdr.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; showing some parameters, the measurement range, and recording intervals. The interval is anywhere from 0.125 seconds to 4 seconds depending on the parameter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft may also have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Quick_access_recorder&quot; rel=&quot;nofollow&quot;&gt;Quick Access Recorder&lt;/a&gt; (QAR), which records many parameters (over 2000). However, aircraft are not required to have one and the QAR is not required to survive an accident. Airlines use them for data to improve operations, and they can also be used in less severe crashes for analysis.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-07T16:43:34.400" LastActivityDate="2015-04-07T16:43:34.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5046" PostTypeId="1" CreationDate="2014-05-23T16:52:54.653" Score="8" ViewCount="21943" Body="&lt;p&gt;Having flight date and exact flight number, I would like to know aircraft type (like Boeing 737-400). Is there any service where I can get such information in bulk (for hundreds of flight dates and flight numbers)? I know that flightradar24 provides us with &lt;a href=&quot;http://www.flightradar24.com/data/flights/un190/&quot; rel=&quot;noreferrer&quot;&gt;similar data&lt;/a&gt;, but it doesn't have any &lt;a href=&quot;http://en.wikipedia.org/wiki/API&quot; rel=&quot;noreferrer&quot;&gt;API&lt;/a&gt; to get such information for many cases.&lt;/p&gt;&#xA;" OwnerUserId="2421" LastEditorUserId="946" LastEditDate="2014-05-24T06:14:25.773" LastActivityDate="2019-08-09T21:15:17.260" Title="Where to find information about aircraft type knowing the flight number and date?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5047" PostTypeId="1" AcceptedAnswerId="5056" CreationDate="2014-05-23T18:40:44.727" Score="19" ViewCount="21919" Body="&lt;p&gt;In comments on the answer to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/5005/what-is-the-chord-of-a-wing/&quot;&gt;question about transonic speeds and control surfaces&lt;/a&gt; I came across this comment and I'm having a hard time understanding it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you increase the chord, lift goes up almost linearly and stability&#xA;  decreases, because now the wing's lift force has a longer lever arm in&#xA;  flow direction. By increasing chord, you decrease aspect ratio...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are a few things I am not understanding, but I think they probably relate quite heavily, so I'm going to ask them together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, what is the aspect ratio of the wing?  Is that a reference to the incidence of the wing and how a longer wing would mean a larger percentage of the side of the fuselage is covered by the wing (as seen from the front)?  Or am I way off the mark?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, why does increasing the chord length decrease the stability of the wing? In my mind a longer wing would mean that the craft is more stable because the airflow is being forced into line for a longer period of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, this all relates to how chord length is considered during wing design.  Are there other factors centered on the chord length that should be considered when designing a wing?  And do those factors change depending on the mission of the craft in consideration (eg., trainer v. cargo plane v. jumbo v. Mach 3 spy plane, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2019-02-27T19:33:28.407" Title="How does chord length affect wing design?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5048" PostTypeId="1" AcceptedAnswerId="5055" CreationDate="2014-05-23T18:44:41.420" Score="44" ViewCount="17185" Body="&lt;p&gt;I've read in several answers to questions that when a wing passes the speed of sound the airflow will become detached from the craft towards the rear quarter of the wing (thus making things like elevators ineffective.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does this happen at Mach Speed?  Can it happen at lower speeds as well (in straight and level flight, ie, not stalled)?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2017-05-24T06:03:01.250" LastActivityDate="2021-05-29T16:43:08.967" Title="Why does supersonic flight detach airflow from a wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="5049" PostTypeId="1" AcceptedAnswerId="5052" CreationDate="2014-05-23T18:52:24.397" Score="18" ViewCount="8256" Body="&lt;p&gt;Can the Airbus A380 or Boeing 787 land safely without flaps/slats/spoilers or thrust reversers?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="5517" LastEditDate="2016-10-07T15:02:34.820" LastActivityDate="2016-10-07T15:35:39.700" Title="Can a super land without flaps/spoilers?" Tags="&lt;landing&gt;&lt;flaps&gt;&lt;airbus-a380&gt;&lt;thrust-reverser&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5050" PostTypeId="2" ParentId="5049" CreationDate="2014-05-23T19:19:38.433" Score="12" Body="&lt;p&gt;Any aircraft can land without those devices. I would say that the &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19830723-0&quot; rel=&quot;nofollow&quot;&gt;Gimli Glider&lt;/a&gt; is a nice example, with no power it could not extend its flaps/slats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are used, as @ratchetfreak notes in the comments, to reduce the touchdown speed and, as a consequence, the runway length needed to reach a stop or taxiing velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be noted, also, that a safe landing is mostly defined by the vertical velocity at tochdown, usually in the order of 1-3 feet per second. See for example &lt;a href=&quot;http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001208X07083&amp;amp;ntsbno=LAX97LA061&amp;amp;akey=1&quot; rel=&quot;nofollow&quot;&gt;this accident report&lt;/a&gt; where it states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;mild touchdown rates [...] less than 5 feet per second&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the vertical component is the relevant parameter for a safe landing, and given that without flaps/slats the forward velocity will be larger than usual, the aircraft will have to approach with a shallower angle than the usual 3°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The absence of thrust reversers, as you might imagine, will only affect the braking process.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="16638" LastEditDate="2016-10-07T15:35:39.700" LastActivityDate="2016-10-07T15:35:39.700" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="5051" PostTypeId="2" ParentId="5048" CreationDate="2014-05-23T19:32:54.197" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why does this happen at Mach Speed?  ...can it happen at lower speeds?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It can also happen at lower speeds, it depends on &lt;a href=&quot;https://aviation.stackexchange.com/questions/4992/why-are-swept-wings-better-for-breaking-the-sound-barrier&quot;&gt;how the wing is designed&lt;/a&gt; and the characteristics of the airfoil (camber thickness profile).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At transonic speeds (0.7 - 1.0 Mach) you can have portions of the airfoils in a supersonic region, meaning that you will have a shock front over (and maybe under) your wing. If the shockwave is strong enough, the flow behind it will be (partially) separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft reaches Mach 1 the presence of a shock is guaranteed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aWEWY.jpg&quot; alt=&quot;Wing profile Mach shock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;Image from &lt;a href=&quot;http://en.wikipedia.org/wiki/Transonic&quot; rel=&quot;nofollow noreferrer&quot;&gt;wiki&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the comments more questions have arisen, I will try to address them.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;why does the Shockwave appear?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Short answer: To go back from supersonic to subsonic flow. Supersonic flow is hard to decelerate without a shock, since the air molecules don't &quot;know&quot; what is ahead. The speed of sound is also the speed of small pressure changes, so any signals of what is coming will not reach the air ahead of the shock wave. The air streams along, blissfully unaware of what is coming, until things cannot be maintained and change with a bang.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the shock wave is so extended to reach the ground, it is called Sonic boom: see the section &lt;a href=&quot;http://www.animations.physics.unsw.edu.au/jw/shock-waves.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sonic boom and sound barrier&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/normal.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this NASA article&lt;/a&gt; on normal shocks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of friction, the air molecules next to the body have no velocity relative to the bodies surface. The molecules a bit further away will be able to move, but because of friction with the molecules attached to the body, they will be slowed down.  This phenomena is called a boundary layer. In normal conditions this is the way roughly half of the profile drag is created. The other half is pressure drag. In separated flow, friction drag disappears, but since the separated air mass is at a lower pressure than static pressure, and because it sits on the backward-facing part of the airfoil, its pressure drag contribution is massive.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;why would the shockwave create turbulence? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because is an anisotropic event, it is chaotic in nature, it increases the entropy of the air molecules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature, density, pressure and velocity change by such large amounts at the shock wave (depending on the speed of the supersonic flow, with exact quantities given by solving the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rankine%E2%80%93Hugoniot_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rankine–Hugoniot&lt;/a&gt; equations) and in such an infinitesimally small space that the flow downstream becomes extremely chaotic and non-laminar.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can it happen at lower speeds as well (in straight and level flight, ie, not stalled)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A shock wave can only happen if you have supersonic flow over the wings. Flow separation happens at all speeds. In the end, all flow will separate at the trailing edge.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-09-06T03:26:47.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5052" PostTypeId="2" ParentId="5049" CreationDate="2014-05-23T19:43:50.923" Score="21" Body="&lt;p&gt;Even the largest commercial airliners are able to land without flaps, since flap failures do happen occasionally. See a report &lt;a href=&quot;http://avherald.com/h?article=46d6dd03&quot;&gt;here&lt;/a&gt; where an A380 landed with no flaps. This was at the Auckland, New Zealand airport, where the runway is 3,635 m (11,926 ft) long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots have checklists to follow in the event of issues with flaps, which include information about what speeds they should fly with what amounts of flaps. They simply land at a higher than normal speed. The brakes can end up getting hotter than normal, so they may have to stop and let them cool or have them inspected by emergency services. The tires are designed to deflate with &lt;a href=&quot;http://en.wikipedia.org/wiki/Fusible_plug&quot;&gt;fusible plugs&lt;/a&gt; before high temperatures would cause them to blow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are also tested to make sure they can reject a takeoff at high weights (higher than normal landing weights) using no thrust reversers. Here is a video of the 747-8 doing this test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/qc_v6tXsv6g?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-12-22T17:38:42.943" LastActivityDate="2015-12-22T17:38:42.943" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5053" PostTypeId="2" ParentId="5048" CreationDate="2014-05-23T19:46:16.463" Score="5" Body="&lt;p&gt;It happen on mach speed because that is when the wing will outspeed the pressure wave of it trying to cut through the air resulting in a shockwave when the air slows down again to subsonic speeds this shock is called a recompression shock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oI0p5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shockwave is the cause of the separation. And as you see it can happen at lower than 1 Mach. The minimal airspeed at which supersonic flow happen is called the &lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;critical mach number&lt;/a&gt;. But the speed at which the drag cause by the shock wave become significant is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;drag divergence mach number&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-05-23T19:57:33.763" LastActivityDate="2014-05-23T19:57:33.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5054" PostTypeId="2" ParentId="5047" CreationDate="2014-05-23T21:40:38.067" Score="10" Body="&lt;p&gt;Aspect ratio is defined as&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$AR=\frac{b^2}{S}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $b$ is wing span and $S$ is wing area. For rectangular wing that's the same as &lt;em&gt;span to chord&lt;/em&gt;; using area in the definition side-steps the need to define average chord for more complicated wing shapes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some properties of the wing depend on it's area while other depend on the span:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lift is proportional to area and square of indicated speed (dynamic pressure).&lt;/li&gt;&#xA;&lt;li&gt;Induced drag is &lt;em&gt;inversely&lt;/em&gt; proportional to &lt;em&gt;span&lt;/em&gt; and &lt;em&gt;inversely&lt;/em&gt; proportional to indicated speed.&lt;/li&gt;&#xA;&lt;li&gt;Form drag is proportional to &lt;em&gt;span&lt;/em&gt;, thickness and square of indicated speed.&lt;/li&gt;&#xA;&lt;li&gt;Skin drag is proportional to &lt;em&gt;area&lt;/em&gt; and square of indicated speed.&lt;/li&gt;&#xA;&lt;li&gt;Wave drag is proportional to &lt;em&gt;span&lt;/em&gt;, thickness and grows rapidly above drag divergence mach number.&lt;/li&gt;&#xA;&lt;li&gt;Strength is inversely proportional to span.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For each wing there is an (indicated) speed at which the wing is most efficient as induced drag has reduced already and the other forms of drag didn't yet grow too large.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since induced drag decreases with span, high aspect ratio wings have the optimal point at lower speeds and their total drag at that speed is generally lower. That's why gliders have wings with very high aspect ratio (very long). As the other forms of drag increase with span, for higher speeds, especially supersonic, lower aspect ratio is better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that all the speeds are &lt;em&gt;indicated&lt;/em&gt; speeds. Indicated speed is dynamic pressure expressed as speed at which it occurs at sea level. But as density decreases with altitude, so does indicated speed. Therefore transport jets cruise at modest indicated speeds and can have relatively high aspect ratio wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other consideration is strength. Making long wing strong is difficult, so aircraft that need high manoeuvrability (aerobatic and fighters) can't have wings with high aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for stability, during normal flight position of centre of lift along the wing chord is relatively stable. But there are three conditions that change it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Stall. Pre-stall lift has centre of pressure about quarter chord, but post-stall lift has centre of pressure midchord. The resulting down pitching moment is a good thing in this case.&lt;/li&gt;&#xA;&lt;li&gt;Mach tuck. This is flow separation caused by shock wave forming on the upper surface of the wing as the aircraft approaches speed of sound. The effect is the same as stall, except this time the down pitching moment is bad thing, because further increase of speed is not desired in this case. Supersonic aircraft usually have all moving horizontal stabilizers to have enough elevator authority to compensate for this change.&lt;/li&gt;&#xA;&lt;li&gt;Extension of flaps. These also shift centre of lift more aft and create down pitching moment.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All these effects will be more pronounced in long chord - low aspect ratio - wings.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-05-23T21:40:38.067" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5055" PostTypeId="2" ParentId="5048" CreationDate="2014-05-23T21:57:12.690" Score="57" Body="&lt;p&gt;Flow separation happens when the pressure gradient of the airflow along the flow path becomes too steep. In subsonic flow, the oncoming air is first decelerated ahead of the wing, then swiftly accelerated when it flows around the strongly curved nose section of a wing. This acceleration is the consequence of the wing's curvature.&lt;/p&gt;&#xA;&lt;p&gt;After this acceleration, how will the airflow behave? Will the airflow keep moving in a straight line without further acceleration or deceleration? (which implies that airflow will separate from the wing surface, creating a local vacuum) Or will it faithfully stick to the wing surface? In reality, the air settles at a compromise between the straight path and following the contour, creating decreasing pressure along a surface with increasing curvature and increasing pressure along surfaces with decreasing curvature. More precisely, it is always in an equilibrium between inertial, viscous and pressure forces.&lt;P&gt;&lt;/p&gt;&#xA;&lt;p&gt;This suction not only bends the airflow into following the wing's contour, but also accelerates the air ahead of it. The lower the pressure, the more the air speeds up, such that the total energy of air (the sum of pressure and kinetic energy) stays constant. Therefore, pressure and local speed change in sync.&lt;P&gt;&lt;/p&gt;&#xA;&lt;p&gt;When the curvature decreases further downstream, the flow path becomes straighter and pressure rises again. However, the air particles close to the wing slow down because of friction. The layer of air where this slowing is noticeable is called boundary layer. In it, the deceleration effects due to pressure rise and due to friction add up, and at some point the air comes to a standstill relative to the wing. Where this happens, static air will collect and build up, causing flow separation. Thankfully, the exchange of air across a turbulent boundary layer kicks the slowest air particles downstream, so at moderate angles of attack the air still moves along until it reaches the trailing edge. Only when the suction peak around the nose becomes very high at high angle of attack, the consequent steep pressure rise along the remaining flow path overpowers the possibilities of the turbulent boundary layer, the air decelerates completely and the flow separates. This is a wholly subsonic affair.&lt;/p&gt;&#xA;&lt;P&gt;&#xA;If the wing moves at high subsonic speed, the curvature-created suction accelerates the flow such that it reaches supersonic speed. Now something odd happens: Supersonic flow accelerates further when subsonic flow would decelerate. This is caused by the change in density which is dominant at supersonic speed. Incompressible (= very slow) flow has constant density, and all speed changes affect pressure. At Mach 1, the pressure and density changes are of equal magnitude, and in supersonic flow the density changes dominate. Now we have a supersonic pocket of air on the upper surface of the wing where speed increases and density decreases downstream, and the surrounding subsonic air sees little change in density. This picture should give you some idea how it looks:&#xA;![Lambda shock in high subsonic flow][1]&#xA;&lt;p&gt;The whole wing moves at Mach 0.68. Compare the green color at some distance from the wing with the scale on the left side, which gives the Mach number for each color shade. At the airfoil nose, you see a blue area. This is where the air decelerates - it gets pushed together by the approaching wing. Now follow the colors along the upper side - they quickly turn green, yellow and red as the air is accelerated into the low pressure area (remember, low pressure equals high speed, so the reddest area has the highest local flow speed and the lowest pressure). In subsonic flow, the suction peak would be somewhere between 20% and 30% of chord, and the colors would slowly change back to yellow and green if you move further downstream. Now we have local supersonic flow (everything redder than light orange is supersonic here), and instead of slowly decelerating, the air is speeding up to a maximum Mach number of 1.23 at almost 60% of chord length.&lt;/p&gt;&#xA;&lt;p&gt;This cannot last, and at some point this supersonic pocket collapses. This happens instantly in a shock, and as you know, in a straight shock density increases suddenly and speed decreases such that the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12001/what-causes-the-reduction-in-speed-across-the-shockwave/12003?s=1%7C0.2673#12003&quot;&gt;Mach number after the shock is the inverse of the Mach number ahead of the shock&lt;/a&gt;. In the picture above, boundary layer effects create a lambda shock, which has its name from the Greek letter which looks like the shock pattern here. Aft of the shock, you have subsonic flow again, and a much thicker boundary layer which moves very slowly (blue shade). This is due to the energy conversion through the shock, which converts kinetic energy into heat. But the flow is still attached - even this shock did not cause separation.&lt;/p&gt;&#xA;&lt;P&gt;&#xA;If this pressure rise is big enough, the boundary layer will come to an instantaneous standstill, and then the flow separates. This is the shock induced separation you asked about. Unfortunately, the picture above is the best I could find, and I have none with separated flow aft of the shock. But it helps to show that the center of pressure moves aft. This causes a strong nose-down moment. Also, with higher subsonic Mach numbers directional stability decreases. Now even more nasty things can happen: The location of the shock might move forward and back. This changes the size of the supersonic area, causing lift changes. On a horizontal tail, this will also cause pitch changes. If you change elevator position slightly with such a shock on the horizontal tail, the lift change could be severe and in the opposite direction of what you would expect. This causes total loss of control, just when you need the control surfaces to counteract the Mach effects mentioned above. Also, the shock position could oscillate, causing a buzzing sound and, if you are really unlucky, coupling into an elastic eigenfrequency of your structure, resulting in flutter. Not only on the tail surfaces, but also on the wing, affecting the ailerons as well. Now you can start to see what scared the early pioneers about flying near Mach 1 and why they spoke of a &quot;sound barrier&quot;.&#xA;&lt;P&gt;&#xA;If you fly fully supersonic, this effect goes away because now the shock moves to the trailing edge and stays there. Now everything will be calm again because the shock location stays fixed. This effect was first experienced and survived on April 9, 1945 by [Hans Guido Mutke in a Me-262][3], which briefly flew fully supersonic in a dive. However, even in fully supersonic flow separation is possible, but then because the air flow will not bend more than what can be caused by total vacuum. In hypersonic flow the density changes become so severe that pockets of &quot;air&quot; are possible which do not contain any air, but a vacuum. But this is more an academic case, except for reentry vehicles with a blunt, rear-facing base.&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-05-29T16:43:08.967" LastActivityDate="2021-05-29T16:43:08.967" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="5056" PostTypeId="2" ParentId="5047" CreationDate="2014-05-23T23:49:00.853" Score="15" Body="&lt;p&gt;During design, chord length will be the result of wing span and wing area, because those two are what the designer wants to set. To be more precise, he tries to set a certain wing loading, trying to minimize wing area (and weight) such that the wing creates just enough lift for the estimated aircraft mass in all design cases. Take-off, maximum altitude and minimum turn radius are the classics which drive minimum wing area.&lt;P&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I will focus on aspect ratio, because Jan has already answered the rest with his excellent answer. The higher the aspect ratio, the less the wing tips will influence the airflow around the wing. This means that the wing creates more lift for a given angle of attack, but also that the stall angle of attack is lower. The ratio of wing span to aircraft mass (called span loading) is the driving force for induced drag. However, wing span and aspect ratio will also drive wing structural mass, so you need to find a sound compromise between low induced drag and low wing mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;What is induced drag?&lt;/a&gt; It is the consequence of creating lift over a limited span. The wing creates lift by deflecting air downwards. This happens gradually over the wing's chord, and creates a reaction force orthogonally to the local speed of air. This means the reaction force is pointing up- and slightly backwards. This backwards component is induced drag! The wider the wing is, the more air can be used for lift creation, hence less deflection is needed. Consequently, the backwards tilt of the reaction force is smaller, resulting in less induced drag for the same lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly fast, there is a lot of air mass streaming past the wing per unit of time, so you need to deflect the air only slightly. Your induced drag is small. That is why induced drag changes inversely with air speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you know that for high speed at high density, induced drag is not important. If you design an attack aircraft which has to fly at low altitude, a low aspect ratio will help: The lift increase due to gusts is smaller than with a high aspect ratio wing, and the induced drag is manageable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How the lift curve slope changes with aspect ratio in subsonic flow is shown in the simple plot below. For a slender body (aspect ratio $\approx$ 0), the gradient of the lift coefficient $c_L$ over angle of attack $\alpha$ is $c_{L\alpha} = \frac{\pi \cdot AR}{2}$. Please note that the red line is only valid for AR = 0! Then the lift curve slope increases up to $c_{L\alpha} = 2\cdot\pi$  for $AR = \infty$ (and zero airfoil thickness and no friction effect), as shown by the blue line.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/KRknE.png&quot; alt=&quot;lift curve slope over AR&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more influences, however. Dihedral means that the lift is tilted inwards, and the part which counteracts weight is only growing with the cosine of the dihedral angle $\nu$. Same goes for sweep: Sweeping means that the wing only sees a reduced angle of attack change. If you want to capture all effects, a plot will not suffice. Here is a table with formulas for most cases:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ZNjfm.png&quot; alt=&quot;Lift curve slope formulas&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_{L\alpha} \:\:$ lift coefficient gradient over angle of attack&lt;br&gt;&#xA;    $c_{L\alpha\:ic} \:$ lift coefficient gradient over angle of attack in incompressible flow&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\nu \:\:\:\:\:$  the wing's dihedral angle&lt;br&gt;&#xA;    $\varphi_m \:\:$  sweep angle of wing at mid chord&lt;br&gt;&#xA;    $\varphi_{LE} \:$  sweep angle of wing at leading edge&lt;br&gt;&#xA;    $\lambda \:\:\:\:\:$  taper ratio (ratio of tip chord to root chord)&lt;br&gt;&#xA;    $(\frac{x}{l})_{d\:max} \:$  chordwise position of maximum airfoil thickness&lt;br&gt;&#xA;    $Ma \:\:$  Mach number&lt;br&gt;&#xA;&lt;P&gt;&#xA;Another consideration is wing volume: In most aircraft, the wing will hold most of the fuel, and a long-range aircraft needs big tanks. Sometimes, only choosing a lower aspect ratio will give enough wing volume for the required range. In order to keep induced drag constant, the span will be kept the same, so wing area increases with chord length. This has the added benefit of more lift, so less complex high-lift devices are needed. Since the structural mass of such a low aspect ratio wing with simple flaps is relatively low, the only disadvantage is the higher friction drag of this larger wing.&#xA;&lt;P&gt;&#xA;If maneuverability is important, wing span needs to be as small as possible. This reduces inertial moments and roll damping, so the aircraft can accelerate faster into a rolling motion and will reach a higher roll rate. This is extremely important in dogfights when the one who points his radar, gun and rockets at the adversary first will win. Here the chord is chosen for sufficient wing area at the minimum practical wing span.&#xA;&lt;P&gt;&#xA;Now we need to talk about viscous effects. Friction between air molecules and between air and wing. The ratio of inertial to viscous forces is expressed by the Reynolds number, and generally a higher Reynolds number means your friction effects go down, translating into less friction drag and a higher stall angle of attack. Especially for model airplanes, but also for gliders, it is sometimes better to reduce aspect ratio in order to gain absolute wing chord. The Reynolds number increases linearly with wing chord, and this can also be a consideration for choosing wing chord.&#xA;&lt;P&gt;&#xA;A normal wing has positive camber, and this means that the center of pressure moves forward with increasing angle of attack. Moment-wise, this means that the wing will create a stronger pitch-up moment when it pitches up. This makes the wing by itself unstable, and you need a tail surface to regain stability. Making wing chord longer will increase the unstable influence of the wing relative to the unchanged tail surface. This is why I said that increasing chord will decrease stability. During design, you watch for a size called tail volume. This is the area of the horizontal tail surface, multiplied with it's lever arm expressed as a multiple of the wing's reference chord. If you keep this constant while changing wing chord, your stability stays the same. But then you change your pitch damping, because this is affected by the square of the lever arm. Digging deeper will uncover more consequences, so I better stop here for today.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-04T19:23:15.213" LastActivityDate="2017-10-04T19:23:15.213" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5057" PostTypeId="2" ParentId="5049" CreationDate="2014-05-24T03:20:56.207" Score="18" Body="&lt;p&gt;Specific information can be difficult to come by, and each airline may have their own guidance on the subject. I wasn't able to find anything for the 787, but for the according to one &lt;a href=&quot;http://www.reddit.com/r/MH370/comments/20q9u9/for_those_interested_the_boeing_777224_flight/&quot; rel=&quot;nofollow&quot;&gt;777 crew handbook I found&lt;/a&gt;, flaps up landing was not part of certification:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;All Flaps and Slats Up Landing&lt;/strong&gt;&lt;br&gt;&#xA;  The probability of both leading and trailing edge devices failing to extend is &#xA;  extremely remote. System reliability and design have reduced the need for some &#xA;  traditional non-normal landing procedures. As a result, an all flaps up landing &#xA;  NNC was not required for airplane certification and does not appear in the AFM &#xA;  or in the QRH.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically this means that a demonstration of a no-flaps landing was not required during certification, so no specific guidance appears in the official handbook, and the manufacturer makes no claim that it can be done safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of the Boeing 787 handbooks I found had official procedures for a flaps-up landing either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That doesn't mean that it can't be done, but pilots are &quot;on their own&quot; so to speak, and the airplane may not be usable afterward.&lt;sup&gt;[*]&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the basic procedure you'd expect them to follow is somewhere along these lines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Attempt to troubleshoot flaps first (best to avoid the problem altogether)&lt;/li&gt;&#xA;&lt;li&gt;Remove excess fuel (either dump or burn)&lt;/li&gt;&#xA;&lt;li&gt;Pick suitable airport considering runway length, altitude, and safety gear (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Engineered_materials_arrestor_system&quot; rel=&quot;nofollow&quot;&gt;EMAS&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Declare emergency and prepare airport (ready the fire trucks, etc)&lt;/li&gt;&#xA;&lt;li&gt;Approach above no-flaps stall speed and touchdown as close to the start of the runway as possible&lt;/li&gt;&#xA;&lt;li&gt;Engage brakes, spoilers, and thrust-reversers as appropriate&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&quot;Please please please stop...&quot;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;Write a book.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[*]&lt;/sup&gt; &lt;em&gt;&quot;If you can walk away from a landing, it's a good landing. If you use the airplane the next day, it's an outstanding landing.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="2426" LastEditorUserId="2426" LastEditDate="2016-10-07T04:35:02.953" LastActivityDate="2016-10-07T04:35:02.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5058" PostTypeId="2" ParentId="5046" CreationDate="2014-05-24T07:02:32.407" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;FlightAware&lt;/a&gt; will give you all the info and &lt;a href=&quot;http://flightaware.com/commercial/flightxml/&quot; rel=&quot;nofollow&quot;&gt;has an API&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2430" LastEditorUserId="1696" LastEditDate="2015-12-22T16:38:24.613" LastActivityDate="2015-12-22T16:38:24.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5059" PostTypeId="1" AcceptedAnswerId="5061" CreationDate="2014-05-24T10:09:44.483" Score="4" ViewCount="318" Body="&lt;p&gt;What is the rationale for the figures &lt;code&gt;5,700 Kg&lt;/code&gt; and &lt;code&gt;19 passengers&lt;/code&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Excerpt from TCAS's Wikipedia entry page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is a type of airborne collision avoidance system mandated by the&#xA;  International Civil Aviation Organization to be fitted to all aircraft&#xA;  with a maximum take-off mass (MTOM) of over 5,700 kg (12,600 lb) or&#xA;  authorized to carry more than 19 passengers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="247" LastEditorUserId="1696" LastEditDate="2015-02-20T22:12:24.770" LastActivityDate="2015-02-20T22:12:24.770" Title="What is the rationale of a weight/passenger value for the ICAO TCAS requirement?" Tags="&lt;icao-sarps&gt;&lt;tcas&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5060" PostTypeId="1" AcceptedAnswerId="5064" CreationDate="2014-05-24T17:33:03.143" Score="8" ViewCount="33884" Body="&lt;p&gt;I'm a student pilot, the question I am trying to answer is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What would be the ground roll and total distance to clear a 50ft obstacle given an elevation of 5,000ft, altimeter 29.52, and a temperature of 25° Celsius, winds calm.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Disclaimer: I'm going to double check with my CFI, obviously, you should too if you are unsure.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/w8YSn.png&quot; alt=&quot;C152 Takeoff performance chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I understand how the chart works, I'm just unclear about the &quot;Elevation 5,000ft. Altimeter at 29.52&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My inclination is to assume that the meaning is sea level pressure is 29.52, and therefore we should adjust our input for &quot;PRESS ALT FT&quot; to be the altitude that reflects that average pressure, which would be 500 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We round up for safety, so assume PRESS ALT=1000' and TEMP=30° Celsius, we would have a ground roll of &lt;code&gt;890'&lt;/code&gt; and a takeoff distance of &lt;code&gt;1645'&lt;/code&gt;, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another question: Where do I find the official documentation for converting barometric pressure into the altitude that has that average pressure?&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="718" LastEditDate="2014-05-25T16:02:15.150" LastActivityDate="2014-05-25T16:02:15.150" Title="What would be the ground roll and total distance to clear a 50ft obstacle given these conditions?" Tags="&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5061" PostTypeId="2" ParentId="5059" CreationDate="2014-05-24T19:52:11.897" Score="6" Body="&lt;p&gt;The numbers aren't random, though at first glance the rationale may not be obvious.&lt;/p&gt;&#xA;&lt;h3&gt;Weight&lt;/h3&gt;&#xA;&lt;p&gt;5700 kilograms is (roughly) 12,500 pounds - This aligns with the FAA definition of a &amp;quot;large aircraft&amp;quot; (an aircraft with a maximum certificated takeoff weight of more than 12,500 pounds).&lt;br /&gt;&#xA;Large aircraft tend to be &amp;quot;working airplanes&amp;quot; in passenger or cargo service, and will be operating to/from busy terminals. They will therefore benefit substantially from TCAS, and the operators can theoretically afford to equip their fleets.&lt;/p&gt;&#xA;&lt;h3&gt;Seating Capacity&lt;/h3&gt;&#xA;&lt;p&gt;Carrying more than 19 passengers further includes aircraft which may not be &amp;quot;large aircraft&amp;quot; but might be used as &amp;quot;working airplanes&amp;quot; in regular airline/commuter service carrying passengers (and would therefore benefit from TCAS, and theoretically be producing revenue to offset the cost of equipping them).&lt;/p&gt;&#xA;&lt;p&gt;This roughly aligns with FAR 121.391 flight attendant requirements (Even relatively small aircraft - maximum payload of 7,500 pounds or less - are required to have a flight attendant on board to assist in evacuation in the event of an emergency, so it logically follows that such aircraft should be equipped with TCAS to avoid at least one possible type of emergency (mid-air collision).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As Federico pointed out, this is largely a cost/benefit trade off (nobody would argue for a flight attendant on a Cessna 150, similarly the TCAS safety features would be overkill for most Cessna 150s in the world).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-24T19:52:11.897" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5062" PostTypeId="1" AcceptedAnswerId="5063" CreationDate="2014-05-24T21:06:46.500" Score="13" ViewCount="2494" Body="&lt;p&gt;I'm not even close to an aviation enthusiast, but after watching some videos I found I have a deep misunderstanding on how airplanes work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GVPua.gif&quot; alt=&quot;airplane image showing engine producing thrust and pushing the plane forwards&quot;&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen many cases where one of the engines fail and the plane has to fly on a single engine for a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How doesn't the fact that the forces are now uneven drive the airplane to a side drift? (I'm sure this is all wrong, but I just don't understand how)&lt;/p&gt;&#xA;" OwnerUserId="2353" LastEditorUserId="2353" LastEditDate="2019-05-29T03:12:25.563" LastActivityDate="2019-05-29T03:12:25.563" Title="How does an engine failure affect the flight of an airplane?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;engine-failure&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="5063" PostTypeId="2" ParentId="5062" CreationDate="2014-05-24T21:21:19.237" Score="18" Body="&lt;p&gt;It does.  Asymmetric thrust will in fact force the airplane into a turn unless the pilot counteracts this by using rudder and aileron to command an equal turn force in the other direction.  Typically both opposing rudder, and banking away from the dead engine will be used to result in straight (although uncoordinated) flight.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-05-24T21:21:19.237" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="5064" PostTypeId="2" ParentId="5060" CreationDate="2014-05-25T04:11:20.733" Score="11" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;We round up for safety, so assume PRESS ALT=1000' and TEMP=30°&#xA;Celsius, we would have a ground roll of 890' and a takeoff distance of&#xA;1645', right?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Good thinking, but no.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Refer to the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2010.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge, Chapter 10&lt;/a&gt;.  You want page 10-3 specifically.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;When the altimeter setting is 29.92, the pressure altitude is the same as the field elevation.&lt;/strong&gt;  When the altimeter setting changes, you must apply a conversion factor to the field elevation to get pressure altitude.&lt;/p&gt;&#xA;&lt;p&gt;In this case, the altimeter setting is 29.52, which means that your conversion factor will be about 380 feet:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jksxg.png&quot; alt=&quot;Image from PHAK showing altitude correction of 380 feet&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Therefore, the actual pressure altitude will be &lt;strong&gt;5,380&lt;/strong&gt; feet.&lt;/p&gt;&#xA;&lt;p&gt;If you round up for safety, the takeoff distances will be &lt;code&gt;1455&lt;/code&gt; and &lt;code&gt;2855&lt;/code&gt;.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;We can get a little more precise than that, though.&lt;/h2&gt;&#xA;&lt;p&gt;To calculate the ground roll at 25 celsius, we can interpolate between 20 and 30 degrees:&lt;/p&gt;&#xA;&lt;h3&gt;5,000 feet&lt;/h3&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(1315 - 1215\right) \over 2 \right] + 1215 = 1265$&lt;/span&gt; ground roll at 5000&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(2525 - 2320\right) \over 2 \right] + 2320 = 2422$&lt;/span&gt; 50 ft obstacle at 5000&lt;/p&gt;&#xA;&lt;p&gt;To correct for pressure altitude, we do the same thing at 6000 feet...&lt;/p&gt;&#xA;&lt;h3&gt;6,000 feet&lt;/h3&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(1455 - 1345\right) \over 2 \right] + 1345 = 1400$&lt;/span&gt; ground roll&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(2525 - 2320\right) \over 2 \right] + 2320 = 2732$&lt;/span&gt; 50 ft obstacle&lt;/p&gt;&#xA;&lt;p&gt;...and then interpolate again:&lt;/p&gt;&#xA;&lt;h3&gt;5,380 feet&lt;/h3&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(1400 - 1265\right) * 0.380 \right] + 1265 = 1316$&lt;/span&gt; ground roll&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\left[ \left(2732 - 2422\right) * 0.380 \right] + 2422 = 2540$&lt;/span&gt; 50 ft obstacle&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-25T04:11:20.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5065" PostTypeId="1" CreationDate="2014-05-25T08:58:27.050" Score="6" ViewCount="1866" Body="&lt;p&gt;Is there any hang glider with &lt;a href=&quot;http://sunbotco.com/solarsheet.php&quot;&gt;solar sheets&lt;/a&gt; on top that can charge the &lt;a href=&quot;http://www.icaro2000.com/Products/Trike/Trike.htm&quot;&gt;e-trike&lt;/a&gt; or the &lt;a href=&quot;https://www.youtube.com/watch?v=l85l-5dbodA&quot;&gt;e-Lift's&lt;/a&gt; battery in flight ? Just like the &lt;a href=&quot;http://www.gizmag.com/sunseeker-solar-powered-aircraft-in-paris/15512/picture/116674/&quot;&gt;Sunseeker&lt;/a&gt;...&lt;/p&gt;&#xA;" OwnerUserId="1953" LastEditorUserId="1467" LastEditDate="2016-03-31T13:51:34.757" LastActivityDate="2016-03-31T14:50:57.580" Title="Is it technically feasible to make a solar hang glider?" Tags="&lt;electrical-system&gt;&lt;hang-glider&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5066" PostTypeId="1" AcceptedAnswerId="5067" CreationDate="2014-05-25T09:49:33.357" Score="5" ViewCount="1051" Body="&lt;p&gt;In my understanding the afterbody is everything trailing behind the nose of the craft excluding the wings and fuselage, and will thus include the empanage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exaclty is meant by the afterbody?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2014-05-27T06:20:43.290" Title="What exactly is the afterbody of an aircraft?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5067" PostTypeId="2" ParentId="5066" CreationDate="2014-05-25T11:30:34.897" Score="5" Body="&lt;p&gt;Each vessel, whether land, sea, or air, should (might) have a defined afterbody. The afterbody is &lt;a href=&quot;http://en.wiktionary.org/wiki/afterbody&quot; rel=&quot;nofollow noreferrer&quot;&gt;defined&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The afterpart of a vehicle; The part of a vessel abaft midships; A companion body that trails a satellite or spacecraft; A section or piece of a launch vehicle, rocket, or spacecraft that enters the atmosphere unprotected behind the nose cone or other body that is protected for entry&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and Merriam-Webster Online &lt;a href=&quot;http://www.merriam-webster.com/dictionary/afterbody&quot; rel=&quot;nofollow noreferrer&quot;&gt;defines&lt;/a&gt; it as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;:  the after part of a body: such as&lt;br&gt;&#xA;  a :  the part of a ship abaft midships&lt;br&gt;&#xA;  b :  the bottom portion of a seaplane hull or float aft of the main step  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To show you, visually, an easy to see set of examples, consider the following pictures of floatplanes (seaplanes):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7x4qr.jpg&quot; alt=&quot;Flying boat 1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/p0b4r.jpg&quot; alt=&quot;Flying boat 2&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/BW05k.jpg&quot; alt=&quot;Flying boat 3&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first and second images, the afterbody is that part of the aircraft behind the step, which is the little 'notch' or, well, 'step' just behind the main wheels. In the third picture, the afterbody is everything after the step, which is the more steeply angled section under the wings. The step is generally just aft of the center of gravity of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, if one were to discuss the afterbody of a large airliners, such as the Airbus A380, the afterbody would be the fuselage from the wings back, but not including the tail (where the rudder and elevators are.) I could not find any Airbus references to 'afterbody' however. I did find some references to the afterbody of a Boeing 787, being that part of the plane behind the pressurized cabin, which is the very back of the plane, including the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not a very good solid definition where everyone agrees, sorry.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2014-05-25T11:38:54.703" LastActivityDate="2014-05-25T11:38:54.703" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5068" PostTypeId="1" AcceptedAnswerId="5069" CreationDate="2014-05-25T12:26:45.260" Score="13" ViewCount="4867" Body="&lt;p&gt;I see helicopters which have air filters in their engine intakes, but jet fighters and commercial turbojet airliners don't seem to have any filters in their air intakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Isn't it true that even tiny particles can damage the turbofan's blades, especially since they rotate at such high speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What if the aircraft has to fly through a dusty area?&lt;/p&gt;&#xA;" OwnerUserId="2434" LastEditorUserId="1696" LastEditDate="2018-04-30T01:44:59.810" LastActivityDate="2019-10-25T03:48:54.783" Title="Do aircraft engine intakes require air filters?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5069" PostTypeId="2" ParentId="5068" CreationDate="2014-05-25T12:45:11.987" Score="11" Body="&lt;p&gt;Dust does damage the blades but the effect is like sand blasting; it takes some time to cause structural damage. The turbine engines of airliners can take some dust (by design) but also get extensive maintenance regularly. And if they do get caught in a dust storm they should get out ASAP and get the engines inspected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest danger dust-wise is volcanic ash as that will adhere to the turbine blades behind the combustion chamber and potentially shut the engine down due to compressor stall. This happened with &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_9&quot;&gt;British Airways Flight 9&lt;/a&gt; where all 4 engines failed. This is why a volcano can &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_travel_disruption_after_the_2010_Eyjafjallaj%C3%B6kull_eruption&quot;&gt;shut down Europe airspace&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="938" LastEditDate="2014-05-27T18:58:31.940" LastActivityDate="2014-05-27T18:58:31.940" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5070" PostTypeId="1" CreationDate="2014-05-25T16:27:25.313" Score="11" ViewCount="2142" Body="&lt;p&gt;We were plotting flightpaths as practice in programming class but unfortunately that was limited to some recordings from a research aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I'm wondering if I can pick up the raw data files from (accident) Flight Data Recorders somewhere to see if I can plot them as well?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Like a file with rows listing time, position, altitude, airspeed etc.)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-05-25T17:24:25.167" LastActivityDate="2016-03-23T22:26:40.517" Title="Is there anywhere I can pick up raw flight data recorder information?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5071" PostTypeId="1" CreationDate="2014-05-25T16:52:15.697" Score="15" ViewCount="4148" Body="&lt;p&gt;FCOM limitations for many aircraft state:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DO NOT USE HF RADIO WHILE REFUELING&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why is this? I have heard from people that it's because most of the big airliners have a 'notch' antenna for HF; it's a small notch cut at the base of the vertical stabiliser. HF transmission power is fed to this notch and the whole fuselage acts as an antenna,&#xA;radiating the power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone explain in detail and in simple terms?&lt;/p&gt;&#xA;" OwnerUserId="2437" LastEditorUserId="97" LastEditDate="2014-05-25T17:58:47.117" LastActivityDate="2018-05-13T20:30:01.540" Title="Why shouldn't you use HF radio while refueling?" Tags="&lt;radio-communications&gt;&lt;avionics&gt;&lt;fuel&gt;&lt;ground-operations&gt;&lt;radio&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5072" PostTypeId="2" ParentId="5071" CreationDate="2014-05-25T18:50:16.063" Score="1" Body="&lt;p&gt;That power can cause sparks when it gets grounded through the fuel opening, that spark can ignite the tank. (Ref: &lt;a href=&quot;https://aviation.stackexchange.com/questions/5071/why-shouldnt-you-use-hf-radio-while-refueling#comment9343_5071&quot;&gt;ratchet freak&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-05-25T18:50:16.063" CommentCount="0" CommunityOwnedDate="2014-05-25T19:47:02.333" ContentLicense="CC BY-SA 3.0" />
  <row Id="5073" PostTypeId="1" AcceptedAnswerId="5129" CreationDate="2014-05-25T21:08:42.500" Score="8" ViewCount="591" Body="&lt;p&gt;During a take-off roll out down the runway, in a tail-dragger airplane, what is the period of time called where the plane is level, with the main gear still on the runway, but the tail has come up off the ground and before you pull back on the stick to begin climb-out?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="1696" LastEditDate="2015-02-20T23:36:47.797" LastActivityDate="2015-02-21T17:38:59.937" Title="What do you call the portion of a tail-dragger takeoff when the tail is in the air?" Tags="&lt;takeoff&gt;&lt;terminology&gt;&lt;tail-dragger&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5074" PostTypeId="1" AcceptedAnswerId="5113" CreationDate="2014-05-25T21:13:01.377" Score="13" ViewCount="1098" Body="&lt;p&gt;What is the 'perfect landing' in a tail-dragger? Do you try to float down to a main-gear landing at minimal descent speed, or do you attempt to float to the point where your tail will either start to come down, or does come down? In other words, is a two-point touchdown or a three-point touchdown more 'perfect.'?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2017-01-20T08:52:59.590" LastActivityDate="2017-01-20T08:52:59.590" Title="What makes the perfect landing in a tail-dragger?" Tags="&lt;landing&gt;&lt;tail-dragger&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5075" PostTypeId="1" AcceptedAnswerId="5077" CreationDate="2014-05-25T21:19:11.077" Score="17" ViewCount="21910" Body="&lt;p&gt;If there is such a thing as a 'normal' flight (in a commercial airliner), who flies the plane? Is it usually the Captain, the First Officer, or whomever needs the hours?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="100" LastEditDate="2020-04-28T08:02:25.833" LastActivityDate="2020-04-28T08:02:25.833" Title="In an airliner, does the Captain or the First Officer fly the airplane?" Tags="&lt;commercial-operations&gt;&lt;crew-resource-management&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5076" PostTypeId="2" ParentId="5075" CreationDate="2014-05-25T21:41:33.380" Score="5" Body="&lt;p&gt;Both pilots will log time for the flight, although their log entries will be slightly different. The captain will log hours as Pilot-in-Command (PIC). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5114/why-is-the-autopilot-called-george&quot;&gt;George&lt;/a&gt;&quot; (the autopilot) will probably actually fly the plane.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-05-28T01:07:55.760" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5077" PostTypeId="2" ParentId="5075" CreationDate="2014-05-25T22:44:14.353" Score="23" Body="&lt;p&gt;At the commercial airline level, there is very little difference between a captain and a first officer, other than the amount of time that they have been at the company (seniority).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, each of the two pilots takes turns flying the airplane.  For instance, if today's trip is from Miami to Charlotte to Chicago to Atlanta to Miami, the captain may fly from Miami to Charlotte, the first officer from Charlotte to Chicago, the captain from Chicago to Atlanta, and the first officer from Atlanta back to Miami.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The duties in the cockpit are divided between the &lt;strong&gt;Pilot Flying&lt;/strong&gt; (PF) and the &lt;strong&gt;Pilot Not Flying&lt;/strong&gt; (PNF)/&lt;strong&gt;Pilot Monitoring&lt;/strong&gt; (PM).  These duty positions are independent of the captain/first officer designation.  The PF is responsible for physically flying the airplane (usually only during takeoff and landing) and for controlling the autopilot.  If the autopilot acts up, the PF immediately takes over.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-05-25T22:44:14.353" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="5078" PostTypeId="1" CreationDate="2014-05-25T22:48:03.443" Score="19" ViewCount="11764" Body="&lt;p&gt;I am watching the video &lt;a href=&quot;https://www.youtube.com/watch?v=pWpSAfF6elI&quot;&gt;NTSB Animation Flight 1549 Hudson River Landing US Airways &lt;/a&gt; (Youtube) and at 0:36 in the video, after the bird strike, you see the following dialogue:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;HOT-1: my aircraft&#xA;HOT-2: your aircraft&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I was curious to know what the formalities behind this is.  Could &lt;code&gt;HOT-2&lt;/code&gt; also claim the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2439" LastEditorUserId="100" LastEditDate="2020-05-05T11:12:24.070" LastActivityDate="2020-05-05T11:12:24.070" Title="How is aircraft control positively transferred between pilot flying and pilot not-flying?" Tags="&lt;emergency&gt;&lt;accident-investigation&gt;&lt;crew-resource-management&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5079" PostTypeId="2" ParentId="5078" CreationDate="2014-05-25T23:32:10.540" Score="5" Body="&lt;p&gt;During the flight, there is a pilot flying (PF) who is in control of the plane, and a pilot not flying (PNF), who is monitoring communications, systems, navigation, and other things. In order to avoid confusion, or a situation where both pilots are trying to make different control inputs for the plane, it should be clear who is in control. If the PNF wants to take control of the plane, they must say &quot;my aircraft&quot;, and the PF must acknowledge &quot;your aircraft&quot;. The PNF now knows that they are in control, and they become the PF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the captain would be more experienced pilot, and take control in difficult situations (like in the US Airways 1549 flight you linked to). However, if the first officer feels it necessary, he or she should be able to also ask for control of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-05-25T23:32:10.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5080" PostTypeId="2" ParentId="2570" CreationDate="2014-05-25T23:46:33.013" Score="1" Body="&lt;p&gt;I suppose if it were an emergency (Not like torn radio aerial, more like fuel&#xA;leaking/low in the middle of the ocean) you could save yourself by ditching&#xA;the plane, parachuting onto the aircraft carrier.  You'd be arrested by armed&#xA;navy men, but as long as you don't try to fight back, you'll be taken to&#xA;wherever they're going in the brig - alive. (And not drowned, marooned, or eaten&#xA;by sharks)  This of course would be after you beg over the radio to land.&#xA;If they say yes, you can save your plane, maybe buy some of their fuel, and&#xA;take off for wherever you're going (or be arrested with your plane, get taken&#xA;to wherever they're going, and pay for a hangar there while you figure things out.&#xA;Not sure what navy protocol on this is.&lt;/p&gt;&#xA;" OwnerUserId="2441" LastActivityDate="2014-05-25T23:46:33.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5081" PostTypeId="2" ParentId="5078" CreationDate="2014-05-26T00:01:47.307" Score="18" Body="&lt;p&gt;What you're quoting is the verbal portion of an important principle called &lt;strong&gt;Positive Exchange of Controls&lt;/strong&gt;. This is a process of ensuring that someone (and only one) is always in control of the aircraft, and that there is no doubt about which pilot that is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best practice, taught to student pilots, is a &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=36&amp;amp;sID=196&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;three-stage handoff procedure&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilot A: You have the flight controls.&lt;br/&gt;&#xA;  Pilot B: I have the flight controls.&lt;br/&gt;&#xA;  Pilot A: You have the flight controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pilot A is the &lt;a href=&quot;https://aviation.stackexchange.com/a/5077/136&quot;&gt;Pilot Flying&lt;/a&gt; before the handoff, and Pilot B is the Pilot Flying after the handoff. In an emergency situation like the above, the captain (Captain Sullenberger, HOT-1, in this transcript) is responsible for the safety of the aircraft, and can assign control as they determine is best. Skipping the first line of the handoff is a reasonable way of making this happen  quickly, while not giving up much in terms of clarity. The two-stage transfer also can happen whenever someone, generally more experienced or in a teaching role, wants to be in control of the aircraft. As DJClayworth points out, a CFI will commonly take the controls in this fashion if they wish to demonstrate a maneuver - no imminent danger required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HOT-2 refers to the &quot;hot microphone&quot;, or recorded feed from the pilots' headset mics, from the first officer. Any time there's a change in Pilot Flying (if the captain gets up to go to the bathroom, for example), the controls should be exchanged in a manner similar to what we see above. If the FO feels that they should have the controls, they can always ask. There is no standard procedure for refusing the exchange of controls, but generally, if the Pilot Flying does not reply to the request with something along the lines of &quot;You have the controls&quot;, then the exchange is incomplete, and the role of Pilot Flying has not changed.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-05-26T15:05:38.957" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5082" PostTypeId="2" ParentId="5075" CreationDate="2014-05-26T03:21:47.817" Score="17" Body="&lt;p&gt;As has been said in previous answers, the duties are divided between the PF and PNF, and the Captain and First Officer typically change which they will do each leg. However, company policy may specify changes to this procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the first 747 carrier I worked for specified that approaches and landings to runway 13 at Kai Tek, the old Hong Kong airport, with it's supposed difficulties, were to be conducted by the Captain. They also had a rule that first officers were not allowed to fly instrument approaches below certain minimums until they had accumulated a certain number of hours in the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second 747 carrier I worked for had a rule against first officers taxing the airplane, this a result of some taxi problems they had had with first officers at the tiller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all instances, after I transitioned to the left seat at both of those carriers, I ignored those rules as I felt they were not only unnecessary but counter-productive. In a few instances I had first officers decline to do these things when offered, but the vast majority were happy to take advantage of the opportunity.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-26T03:21:47.817" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5083" PostTypeId="1" CreationDate="2014-05-26T05:47:38.083" Score="3" ViewCount="918" Body="&lt;p&gt;I live in NYC and my house is under one of the approaches for JFK. Im still about 15 miles away from JFK, so the noise isn't an issue 99% of the time. Once in a while however, especially if I'm outside, I notice that the plane is much louder and seems to be visibly lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? I'd figure with all the fancy GPS and radar systems planes and ATC have that the landings would be near identical, but this doesn't seem to be the case.&lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="247" LastEditDate="2014-05-26T06:07:01.250" LastActivityDate="2014-05-26T06:34:42.793" Title="Why do planes make landing approaches at significantly varying heights?" Tags="&lt;landing&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5084" PostTypeId="1" AcceptedAnswerId="5088" CreationDate="2014-05-26T06:06:25.040" Score="4" ViewCount="3964" Body="&lt;p&gt;In the movie Flight, Denzel Washington's plane loses one engine and some other controls. To keep the plane gliding, he inverts the plane until it reaches a very low altitude. At the last second he flips it back right side up so that the belly of the aircraft takes the grunt of the crash landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously this is all hollywood and takes a lot of creative license, but I'm a bit curious as to how realistic it was. Would you actually be able to fly a large jet upside down like that? &lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="97" LastEditDate="2014-10-27T21:57:05.920" LastActivityDate="2014-10-27T21:57:05.920" Title="How Realistic (or not) was the crash scene in Flight?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;accidents&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2014-05-26T12:30:09.917" ContentLicense="CC BY-SA 3.0" />
  <row Id="5085" PostTypeId="2" ParentId="5083" CreationDate="2014-05-26T06:22:48.227" Score="7" Body="&lt;p&gt;Unfortunately, since I don't know your particular location relative to the airport, I can only give some general answers as to why this might be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrary to popular belief, the availability of precision approaches does not mean they are used 100% of the time, nor are aircraft always routed the same way. Depending on the airport, the use of precision approaches can drastically reduce the number of aircraft that can be handled in a given period of time.  As such, during visual meteorological conditions, flights will almost always be cleared for a visual approach. Busy airports will typically have a number of standard arrival routes (STARs) that make the approach routing consistent and predictable (which could explain why noise is not an issue 99% of the time), but pilots are not obligated to use them.  If a STAR is not used during a visual approach to an airport with approach control services (like JFK):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The approach controller (using radar) will direct the plane in such a way to allow the pilot to visually acquire the runway, at which point the controller will clear the pilot for a visual approach. Additionally, under radar vectoring, the aircraft may be told to fly a particular heading for sequencing and/or spacing which can vary due to the amount and type of traffic. &lt;/li&gt;&#xA;&lt;li&gt;Once cleared for the visual approach, the particular approach course and altitude is at the pilot's discretion.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The situation is similar for an instrument approach, except that the approach controller will arrange to have the aircraft either navigate to an initial approach fix on a published approach procedure or vectored to intercept the localizer before clearing the pilot for the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes, unusual flight paths can also occur when a runway that is not normally used for landings is made active.  This can happen when wind favors a particular runway, or the one that is normally used is taken out of service (e.g. maintenance or an accident).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-05-26T06:34:42.793" LastActivityDate="2014-05-26T06:34:42.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5086" PostTypeId="1" CreationDate="2014-05-26T07:31:05.520" Score="5" ViewCount="2644" Body="&lt;p&gt;Before landing, without ILS, how can you get the correct vertical angle and know when you're too high or too low?&#xA;I think there are some red and white directionnal lights next to the runway that can tell you if your angle is correct, but I'd like to know precisely how a nice approach is done.&#xA;Do pilots sometime just figure it out because it's a habit? Is it more difficult if the runway is surrounded by an ocean?&#xA;I'm talking about commercial airliners as it seems more simple with small aircrafts.&lt;/p&gt;&#xA;" OwnerUserId="2445" LastEditorUserId="2445" LastEditDate="2014-05-26T08:47:07.393" LastActivityDate="2014-05-26T12:42:58.687" Title="How to get the correct angle when doing a visual appoach before landing?" Tags="&lt;landing&gt;&lt;visual-approaches&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5087" PostTypeId="2" ParentId="5084" CreationDate="2014-05-26T09:20:06.823" Score="1" Body="&lt;p&gt;I'm not familiar with the movie but the scenario described is nonsense. An aircraft that is in good enough shape to perform aerobatics is in pretty damned good shape and could just continue with its flight and perform a normal landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some large aircraft are capable of brief inverted flight. &lt;a href=&quot;http://en.wikipedia.org/wiki/Tex_Johnston&quot; rel=&quot;nofollow&quot;&gt;Tex Johnston&lt;/a&gt; famously barrel-rolled the Boeing 707 prototype in 1965 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_367-80#The_barrel_roll&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, &lt;a href=&quot;https://www.youtube.com/watch?v=AaA7kPfC5Hk&quot; rel=&quot;nofollow&quot;&gt;Youtube&lt;/a&gt;). The &lt;a href=&quot;https://en.wikipedia.org/wiki/Alenia_C-27J_Spartan&quot; rel=&quot;nofollow&quot;&gt;Alenia Spartan&lt;/a&gt;, a Hercules-sized turboprop transport, is also capable of doing barrel rolls and often does so at air shows (&lt;a href=&quot;https://www.youtube.com/watch?v=RAz2rRjasuE&quot; rel=&quot;nofollow&quot;&gt;Youtube&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="520" LastEditDate="2014-05-28T17:25:55.950" LastActivityDate="2014-05-28T17:25:55.950" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5088" PostTypeId="2" ParentId="5084" CreationDate="2014-05-26T11:02:29.830" Score="3" Body="&lt;p&gt;It's apparently loosely based on &lt;a href=&quot;http://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261&quot; rel=&quot;nofollow&quot; title=&quot;Alaska Airlines Flight 261&quot;&gt;Alaska Airlines Flight 261&lt;/a&gt; and like in the actual incident, I don't think he deliberately inverts the plane. In the actual event, the horizontal stabilizer gets jammed in an extreme position thus forcing the plane to invert. Now if it were possible to fly a commercial airplane that big inverted, Alaska Airlines too would've landed safely eventually (which didn't happen, despite the pilots trying to fly it upside down according to the CVR transcripts).&lt;/p&gt;&#xA;" OwnerUserId="2447" LastEditorUserId="1467" LastEditDate="2014-05-26T20:37:27.470" LastActivityDate="2014-05-26T20:37:27.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5089" PostTypeId="2" ParentId="5086" CreationDate="2014-05-26T12:00:11.070" Score="3" Body="&lt;p&gt;&lt;strong&gt;PAPI&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airport might have Precision Approach Path Indicator (PAPI) lights set up. I believe these might be what you are thinking of. They are discussed in Chapter 2 of the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0201.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are two pictures to show them at night.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/qPjfi.jpg&quot; alt=&quot;Correct Glide Path&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YMIuW.jpg&quot; alt=&quot;Too High&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first, shows a plane that is on the correct glide path. Firstly, they are normally installed to the left of the runway, and according to the AIM, red should be on the right, so, I believe the picture has been flipped, however you could still use them as is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are right on the correct glide scope for that runway, you would see two white and two red. .2 degrees high would show three white and one red, and .5 degrees high, or higher, four white.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversly, .2 degrees low will show three red and one white, and .5 degrees low or lower will show all four red.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Red and White is Just Right. All Red, You're Dead.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;VASI&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There might also be VASI, or Visual Approach Slope Indicator, lights. These are in many different configurations. They are also discussed in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0201.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM&lt;/a&gt; at the same link I posted above. An example of a two bar VASI light setup is shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/r4rhb.jpg&quot; alt=&quot;Two Bar VASI&quot;&gt;&lt;br&gt;&#xA;The VASI lights are the two sets of two lights next to the runway (just above the row of green lights. They are set up so that white over white is too high, red and white both showing, on glidepath, and red over red is too low.&lt;br&gt;&#xA;The mnemonic for those is: red over white, alright; red over red, you're dead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, there is the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0201.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM Page&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Precision_approach_path_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;PAPI Wikipedia Page&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_approach_slope_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;VASI Wiki Page&lt;/a&gt;, plus there are many other pages which are useful. If you search (using Google or BING, for example) for &quot;runway lights papi&quot; or &quot;runway lights vasi&quot; you'll get many hits.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One last comment here. The correct glide path for an airport is not always the same. If there is/are an obstacle, the glide path might be higher/steeper. If the runway is lighted, using PAPI and/or VASI lights, use them! They will keep you on the correct glidepath for whatever runway you're trying to use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good Luck and Safe Flying!&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2014-05-26T12:42:58.687" LastActivityDate="2014-05-26T12:42:58.687" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5090" PostTypeId="1" CreationDate="2014-05-26T13:36:43.240" Score="12" ViewCount="1863" Body="&lt;p&gt;&lt;em&gt;This is one of 3 question in &quot;series&quot; - one question split up in 3 to better reward those responding about each aircraft. Other questions: &lt;a href=&quot;https://aviation.stackexchange.com/questions/5094/aerodynamic-data-for-yak-131&quot;&gt;Yak-131&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/5092/aerodynamic-data-drag-lift-curves-for-l-159-alca&quot;&gt;L-159&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A-10 is one 3 planes that are used in the &lt;a href=&quot;http://arma3.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;ArmA 3 combat simulator&lt;/a&gt;, but its aerodynamics modelling currently lacks significantly. I'm planning on writing a short &quot;essay&quot; to developers regarding what and how can be specifically fixed in the flight model, but I'd like to back my research with some hard data. Specifically, I'm interested in any of the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;L/AoA&lt;/li&gt;&#xA;&lt;li&gt;D/AoA&lt;/li&gt;&#xA;&lt;li&gt;Side lift/SA (Slide angle)&lt;/li&gt;&#xA;&lt;li&gt;Max G/velocity&lt;/li&gt;&#xA;&lt;li&gt;Flight envelopes (like one below for F-15):&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iQ3nC.png&quot; alt=&quot;http://img704.imageshack.us/img704/7035/f15str.png&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torques can well be left out - it's not a full fledged simulator, but the above data can give quite a good estimation of high level characteristics already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any good sources on any of the above data? I've found some (see below), but the quality leaves a lot to desire. Low-mach data is good enough for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand this is a tall order, but, well, SE is for expert answers - maybe a wonder happens and someone here has it? :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I've found so far:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/A-10Spr09.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Some superficial modelling of A-10&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.510fs.org/bentwaters-spangdahlem/aircraft-a10&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-10 airfoil: NACA 6716 root, NACA 6713 tip&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://forums.eagle.ru/showthread.php?t=60293&quot; rel=&quot;nofollow noreferrer&quot;&gt;Set of A-10 documentation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1852" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-17T18:41:55.977" Title="What aerodynamic data (drag/lift curves) exists for the A-10?" Tags="&lt;aerodynamics&gt;&lt;datasets&gt;&lt;fairchild&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="5091" PostTypeId="1" AcceptedAnswerId="5093" CreationDate="2014-05-26T14:06:51.737" Score="12" ViewCount="2368" Body="&lt;p&gt;A question about the &lt;a href=&quot;https://aviation.stackexchange.com/q/5078/1289&quot;&gt;&quot;my aircraft&quot; protocol&lt;/a&gt; led to several answers that explain how the pilot flying (PF) can delegate control to the pilot not flying (PNF). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also seems that a pilot (e.g. returning from a break) can assert &quot;I have control&quot; without the other pilot first offering control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I've read, unlike with ATC communications, the exact phrases used vary from airline to airline and are not the subject of rules or guidance by authorities such as the FAA. It also seems that in some airlines, some pilots are more casual about the use of standard phrases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only fixed idea seems to be that as long as both pilots have uttered some complementary phrase, both should now be aware that a transfer of control has occurred, and to whom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This led me to wonder: &lt;em&gt;under what circumstances can the PF refuse the PNF's request, how would they phrase this and does the other pilot or pilots always defer to the senior pilot?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="100" LastEditDate="2020-04-28T08:04:13.737" LastActivityDate="2020-04-28T08:04:13.737" Title="How are conflicts between pilot flying and pilot not-flying over aircraft control resolved?" Tags="&lt;commercial-operations&gt;&lt;crew-resource-management&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5092" PostTypeId="1" CreationDate="2014-05-26T14:27:21.717" Score="7" ViewCount="584" Body="&lt;p&gt;&lt;em&gt;This is one of 3 question in &quot;series&quot; - one question split up in 3 to better reward those responding about each aircraft. Other questions: &lt;a href=&quot;https://aviation.stackexchange.com/questions/5090/aerodynamic-data-drag-lift-curves-for-a-10&quot;&gt;A-10&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/5094/aerodynamic-data-for-yak-131&quot;&gt;Yak-131&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;L-159 Alca is one 3 planes that are used in the &lt;a href=&quot;http://arma3.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;ArmA 3 combat sumilator&lt;/a&gt;, but its aerodynamics modelling currently lacks significantly. I'm planning on writing a short &quot;essay&quot; to developers regarding what and how can be specifically fixed in the flight model, but I'd like to back my research with some hard data. Specifically, I'm interested in any of the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;L/AoA&lt;/li&gt;&#xA;&lt;li&gt;D/AoA&lt;/li&gt;&#xA;&lt;li&gt;Side lift/SA (Slide angle)&lt;/li&gt;&#xA;&lt;li&gt;Max G/velocity&lt;/li&gt;&#xA;&lt;li&gt;Flight envelopes (like one below for F-15):&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iQ3nC.png&quot; alt=&quot;http://img704.imageshack.us/img704/7035/f15str.png&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torques can well be left out - it's not a full fledged simulator, but the above data can give quite a good estimation of high level characteristics already&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any good sources on any of the above data? Low-mach data is good enough for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand this is a tall order, but, well, SE is for expert answers - maybe a wonder happens and someone here has it? :)&lt;/p&gt;&#xA;" OwnerUserId="1852" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-06-27T23:16:15.473" Title="What aerodynamic data (drag/lift curves) exists for the L-159 Alca?" Tags="&lt;aerodynamics&gt;&lt;datasets&gt;&lt;aero-vodochody&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5093" PostTypeId="2" ParentId="5091" CreationDate="2014-05-26T14:31:39.090" Score="16" Body="&lt;p&gt;The whole idea behind the policies and procedures for transferring control of the aircraft between the pilots is so that everybody is always on the same page.  &lt;strong&gt;Somebody&lt;/strong&gt; always needs to be flying the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I want to hand control over to the other pilot, and he doesn't want it/can't take it, he would simply explain why not.  I have never seen standard operating procedures (SOP's) that explain how to refuse, as simply saying no or unable should let the other pilot know that there is a problem and should be the beginning of a conversation about it.  On the other hand, the SOP's &lt;strong&gt;do&lt;/strong&gt; cover the scenario where the other pilot doesn't respond.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why there is always a challenge/response as part of handing off control.  If the other pilot were incapacitated and I didn't realize it, I would say &quot;You have the flight controls&quot; (or whatever phrase that the SOP's require) and wait for his response.  If they didn't respond, I wouldn't just blindly stop flying the airplane and assume that they are.  Instead, I could say it again or look over at them to see what was going on and figure out what the problem was while continuing to fly the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to request control from the other pilot (rather than requesting them to take control), I would simply skip the first part and say &quot;I have the flight controls&quot; and they should respond with &quot;You have the flight controls.&quot;  Again, it's a challenge/response situation so that everybody is on the same page.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In either case, the captain is the final authority and can always override a request.  Airline policies are all very clear that if there is a disagreement, the captain has the &quot;tie breaking&quot; vote.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-05-26T14:53:43.140" LastActivityDate="2014-05-26T14:53:43.140" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="5094" PostTypeId="1" CreationDate="2014-05-26T14:32:21.543" Score="9" ViewCount="757" Body="&lt;p&gt;&lt;em&gt;This is one of 3 question in &quot;series&quot; - one question split up in 3 to better reward those responding about each aircraft. Other questions: &lt;a href=&quot;https://aviation.stackexchange.com/questions/5090/aerodynamic-data-drag-lift-curves-for-a-10&quot;&gt;A-10&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/5092/aerodynamic-data-drag-lift-curves-for-l-159-alca&quot;&gt;L-159&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yak-130 is one 3 planes that are used in the &lt;a href=&quot;http://arma3.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;ArmA 3 combat simulator&lt;/a&gt;, but its aerodynamics modelling currently lacks significantly. I'm planning on writing a short &quot;essay&quot; to developers regarding what and how can be specifically fixed in the flight model, but I'd like to back my research with some hard data. Specifically, I'm interested in any of the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;L/AoA&lt;/li&gt;&#xA;&lt;li&gt;D/AoA&lt;/li&gt;&#xA;&lt;li&gt;Side lift/SA (Slide angle)&lt;/li&gt;&#xA;&lt;li&gt;Max G/velocity&lt;/li&gt;&#xA;&lt;li&gt;Flight envelopes&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Torques can well be left out - it's not a full fledged simulator, but the above data can give quite a good estimation of high level characteristics already&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any good sources on any of the above data? Low-mach data is good enough for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand this is a tall order, but, well, SE is for expert answers - maybe a wonder happens and someone here has it? :)&lt;/p&gt;&#xA;" OwnerUserId="1852" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2018-03-22T03:49:47.487" Title="What aerodynamic data exists for the Yak-130?" Tags="&lt;aerodynamics&gt;&lt;datasets&gt;&lt;yakovlev&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5095" PostTypeId="1" AcceptedAnswerId="5096" CreationDate="2014-05-26T17:00:11.717" Score="12" ViewCount="2905" Body="&lt;p&gt;All modern commercial airliners have a CVR (Cockpit Voice Recorder) on-board to record what the pilots are saying during the duration for a flight. I feel that the location of the microphones is important because they should be in a place that can easily pick up the cockpit conversations but should also be discreet enough to avoid accidental damage or even intentional sabotage by hijackers/suicidal pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So where are the recording devices or microphones located in the cockpit for this? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there more than one microphone in the cockpit to provide stereo sound? &lt;/li&gt;&#xA;&lt;li&gt;If so, do investigators listen to the recording from each microphone?&lt;/li&gt;&#xA;&lt;li&gt;Are there any pictures of these microphones in the cockpit?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="504" LastEditorUserId="97" LastEditDate="2014-10-27T21:59:14.750" LastActivityDate="2015-04-02T00:04:08.463" Title="Where are the microphones for the black box located in the cockpit?" Tags="&lt;safety&gt;&lt;cockpit-voice-recorder&gt;&lt;accident-investigation&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5096" PostTypeId="2" ParentId="5095" CreationDate="2014-05-26T19:27:47.893" Score="14" Body="&lt;p&gt;The headsets worn by the pilots have a microphone arm. These audio channels are split and routed to the black box.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, there is at least one microphone embedded in the cockpit, usually overhead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The black box can support recording of up to 4 audio channels, so each channel can be examined separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the headsets and overhead microphone are inside the cockpit, stereo audio is available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can't find any pictures for you, sorry!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seethis sources:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avstop.com/history/flightrecorder.htm&quot;&gt;Avstop&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/29662c3b5885d29386257180007150b6/%24FILE/TSO-C123b.pdf&quot;&gt;FAA (pdf)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2453" LastEditorUserId="1467" LastEditDate="2014-05-26T20:33:59.503" LastActivityDate="2014-05-26T20:33:59.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5097" PostTypeId="2" ParentId="5095" CreationDate="2014-05-26T20:16:59.220" Score="8" Body="&lt;p&gt;Each of the three crew gets its own array of mics including the hand mic, boom mic, mask mic, his speaker and headphones (the microphone he uses for radio communication and what he hears from the radio). The third crew member's channel may be connected to the PA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fourth required channel is for the cockpit area mic which records general sounds and alerts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.ntsb.gov/safety/safety-recs/recletters/A92_133.pdf&quot; rel=&quot;nofollow&quot;&gt;NTSB&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="923" LastEditDate="2015-03-30T05:03:59.257" LastActivityDate="2015-03-30T05:03:59.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5100" PostTypeId="2" ParentId="4992" CreationDate="2014-05-27T05:28:12.220" Score="2" Body="&lt;p&gt;Swept wings are beneficial at transonic flight regimes (M=0.8-1.2). At transonic flight regimes there is a drastic increase in drag (CD is more or less constant up until that point) due to the effects of compressibility, which manifest themselves in local sonic regions on the wing (the plane itself can be flying at M=0.78, yet over some portions of the wing, where the pressure is low, velocities may go sonic and supersonic). There is a very large amount of wave drag in such regions. The swept wing essentially reduces the effective velocity, so the flow remains subsonic and shocks do not form over the wing, thus not leading to the generation of large amounts of drag. Check out stuff on critical Mach number (drag divergence number).&lt;/p&gt;&#xA;" OwnerUserId="2456" LastActivityDate="2014-05-27T05:28:12.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5101" PostTypeId="1" CreationDate="2014-05-27T05:49:59.287" Score="14" ViewCount="2710" Body="&lt;p&gt;Modern commercial aircraft use stabilizer to trim instead of trim tabs. What are the advantages and disadvantages of this design choice?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have aileron trim and rudder trim evolved in a similar way to move the entire control surface rather than aileron / rudder trim tabs?&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="19" LastEditDate="2016-07-14T08:14:43.893" LastActivityDate="2018-06-11T03:42:17.493" Title="What are the reasons to evolve from trim tabs to moving the entire surface (e.g. stabilizer)?" Tags="&lt;flight-controls&gt;&lt;trim&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5102" PostTypeId="1" AcceptedAnswerId="5111" CreationDate="2014-05-27T06:00:15.653" Score="6" ViewCount="1228" Body="&lt;p&gt;What is the rationale behind the use of electrical motors instead of Hydraulic actuation for the stabilizer which I have seen in most aircraft like Boeing 787.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="19" LastEditDate="2014-05-29T10:52:28.053" LastActivityDate="2014-05-29T10:52:28.053" Title="Why is stabilizer trim often controlled by electric motor while other surfaces are mostly hydraulically controlled?" Tags="&lt;flight-controls&gt;&lt;trim&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5103" PostTypeId="2" ParentId="5066" CreationDate="2014-05-27T06:20:43.290" Score="0" Body="&lt;p&gt;A very good answer I got from user Andries on Eng-Tips Forum:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;The afterbody is the rear section of the fuselage. The airflow in this region is often turbulent and afterbody design therefore has quite significant drag reduction issues . In many jet aircraft the afterbody contains the jet exhausts and their effect adds to the complexity of the design of this part of the fuselage.&quot;&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2014-05-27T06:20:43.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5106" PostTypeId="2" ParentId="5074" CreationDate="2014-05-27T07:43:08.967" Score="4" Body="&lt;p&gt;You can make a perfect &quot;wheelie&quot; landing, depending on the wind and landing runway direction.&lt;br&gt;&#xA;In a crosswind, it is safer to land on the main gear with the one windward wheel (wing low), or both main wheels, thus permitting better rudder control until the tail wheel makes ground contact as speed slows. In a crosswind the landing phase is done with a combo of wing low and/or crabbed into the wind.&lt;br&gt;&#xA;Wind and aircraft load conditions dictate if you can manage a perfect 3 pointer called a &quot;full stall landing&quot;..the aim is to hold it off until the aircraft stalls an inch or so above terrain. By the way, an aircraft can fly in ground effect BELOW its stall speed.&lt;/p&gt;&#xA;" OwnerUserId="2458" LastEditorUserId="2171" LastEditDate="2014-05-27T21:46:45.923" LastActivityDate="2014-05-27T21:46:45.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5107" PostTypeId="2" ParentId="5101" CreationDate="2014-05-27T08:11:19.807" Score="0" Body="&lt;p&gt;Trim tabs let the pilot move the control surface more easily. It is the elevators that actually affect the plane's attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A all moving tail gives more control over the attitude compared to just the control surface. They also allow for more control in stall and transonic conditions (during flow separation) because the pilot can control the leading edge.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-05-27T08:11:19.807" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5108" PostTypeId="1" AcceptedAnswerId="5109" CreationDate="2014-05-27T08:59:02.533" Score="11" ViewCount="86020" Body="&lt;p&gt;What type of fuel is used in helicopters? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they use Aviation Turbine Fuel (jet fuel), which is used widely in commercial airlines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, where would be the fuel tank located in a helicopter?&lt;/p&gt;&#xA;" OwnerUserId="1337" LastEditorUserId="22726" LastEditDate="2019-10-12T05:35:29.123" LastActivityDate="2019-10-12T05:35:29.123" Title="What type of fuel is used in helicopters?" Tags="&lt;helicopter&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;&lt;jet-fuel&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="5109" PostTypeId="2" ParentId="5108" CreationDate="2014-05-27T09:11:26.157" Score="13" Body="&lt;p&gt;It depends on the engine. A piston engine will use avgas (aviation gasoline) or diesel (or Jet-A for availability reasons) depending on whether the engine is a diesel engine (which can burn jet fuel), while a turbine engine will use jet fuel. Essentially whatever the engine is rated to burn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuel tank is somewhere in the fuselage near the center of the rotor. This to avoid the center of gravity shifting with the fuel level.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-29T08:30:59.637" LastActivityDate="2015-01-29T08:30:59.637" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5110" PostTypeId="2" ParentId="5070" CreationDate="2014-05-27T15:59:40.203" Score="4" Body="&lt;h2&gt;The AAIB responded quite quickly (and briefly) but were not very helpful:&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AAIB does not release FDR raw data on any accidents in line with&#xA;  the EU regulation 996/2010 article 14.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Having a look at the &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ%3aL:2010:295:0035:0050%3aEN%3aPDF&quot; rel=&quot;nofollow&quot;&gt;corresponding EU regulation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The safety investigation of accidents and incidents should be&#xA;  conducted by or under the control of an independent safety&#xA;  investigation authority in order to avoid any conflict of interest and&#xA;  any possible external interference in the determination of the causes&#xA;  of the occurrences being investigated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Paraphrased, I don't think they want 'unexperienced' people interpreting data on their own and making conspiracy theories or something I guess :) That being said, the regulation doesn't expressly forbid the distribution of information in my opinion, but I won't bother discussing it further. I think that unless you have a proper reason for it, they won't give it to you.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Update: Paragraph 35 is interesting....&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The rules on access to data&lt;/strong&gt;, data processing and the protection of&#xA;  individuals laid down in relevant legal acts of the Union should be&#xA;  &lt;strong&gt;fully respected in the application of this Regulation&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which &lt;em&gt;may&lt;/em&gt; imply that you could get it, depending on how those are written, which I have absolutely no clue about. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-05-27T16:07:30.160" LastActivityDate="2014-05-27T16:07:30.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5111" PostTypeId="2" ParentId="5102" CreationDate="2014-05-27T16:26:22.327" Score="5" Body="&lt;p&gt;Weight, cost, reliability and maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://dspace.lib.cranfield.ac.uk/bitstream/1826/6282/1/Meng_Fanliang_Thesis_2010.pdf&quot; rel=&quot;noreferrer&quot;&gt;ACTUATION SYSTEM DESIGN WITH ELECTRICALLY POWERED ACTUATORS&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safety&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.icas-proceedings.net/ICAS2006/PAPERS/048.PDF&quot; rel=&quot;noreferrer&quot;&gt;THE A380 FLIGHT CONTROL ELECTROHYDROSTATIC ACTUATORS, ACHIEVEMENTS AND LESSONS LEARNT&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In terms of safety several aspects can be &#xA;  highlighted: As far as power source redundancy &#xA;  is concerned the number is increased from 3 to 4 &#xA;  since 2 electrical systems replace 1 hydraulic &#xA;  system. Furthermore an additional margin of &#xA;  safety results from the introduction of the &#xA;  hydraulic/electric dissimilarity in the power &#xA;  sources: This provides further protection against &#xA;  common failures, such as maintenance errors, &#xA;  which may affect all the hydraulic systems, &#xA;  whatever their number. Moreover the electrical &#xA;  power provides flexibility in routing, resulting &#xA;  in an easier segregation of power distribution &#xA;  routes against engine burst and other “particular &#xA;  risks”, and an isolation and reconfiguration &#xA;  capability that hydraulic systems cannot offer.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The reduction in the total number of hydraulic &#xA;  components results in improvements of the &#xA;  MTBF and dispatch reliability, by elimination &#xA;  of potential leakage sources. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The elimination of the generation and &#xA;  distribution components associated to one of the &#xA;  hydraulic systems (pump, reservoir, filters, &#xA;  plumbing…) and the replacement of the &#xA;  associated hydraulic actuators by electrically &#xA;  powered actuators results in weight savings. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-05-27T16:26:22.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5112" PostTypeId="2" ParentId="5101" CreationDate="2014-05-27T18:34:46.793" Score="7" Body="&lt;p&gt;One reason for moving the entire surface for trimming is efficiency. Deflecting the elevators or trim tabs creates more drag than adjusting the whole surface. The control surfaces are more aerodynamic without trim tab deflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The elevator is the main surface needed for trimming the aircraft. This is because things like fuel and payload will affect the center of gravity (CG), and the elevator is trimmed to balance the airplane. In addition to this, the external loads on the aircraft change throughout the flight from things like thrust settings and lift and drag from the wing. Different airspeeds and extension of flaps, speed brakes, landing gear, etc., will also affect the balance of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Balance left and right is less of an issue, and can be addressed by changing the balance of fuel between tanks. Aerodynamic forces tend to stabilize the aircraft in yaw, so trimming in yaw is really only an issue in rare circumstances. Rudder or thrust settings can be used to adjust as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is the structure of the airplane. The horizontal stabilizer has much less load on it than the wings. The ability to move the tail surface adds weight and complexity to the design, and this would be a much greater challenge with the wing. The efficiency benefits make this design feasible for the horizontal stabilizer, but there aren't enough good reasons to move the vertical stabilizer or the wings to justify the costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft that actually use the entire stabilizer surface for control are in a different situation. These are generally military aircraft that need to maintain high maneuverability, especially at very low or very high airspeeds (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight&quot;&gt;this question&lt;/a&gt;). These aircraft are also generally smaller, so moving a smaller surface is less of a challenge.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-05-30T17:59:22.323" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5113" PostTypeId="2" ParentId="5074" CreationDate="2014-05-27T18:35:05.307" Score="7" Body="&lt;p&gt;They both have their uses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wheel landing (landing on the mains, keeping the tail in the air) gives you better rudder authority on the ground, which is useful in a crosswind or during touch-and-gos. However, there is a point where as your airspeed slows, your rudder authority falls off quickly. This can be dangerous in a crosswind for obvious reasons. Most pilots avoid this condition by keeping the tail up for as long as they can, then quickly planting it on the ground when it begins to fall. The rudder is kept up in the airstream for as long as possible, and then you quickly transfer your turning control from the rudder to the tailwheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A three-point landing is useful for getting on the ground and stopping quickly, because the additional wheel provides more friction. It also avoids the situation in the previous paragraph, because you land with the tailwheel down and have full turning authority the entire time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in general, there is no preferred landing style in a tailwheel airplane. This may not be true for specific models of aircraft, however.&lt;/p&gt;&#xA;" OwnerUserId="277" LastActivityDate="2014-05-27T18:35:05.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5114" PostTypeId="1" AcceptedAnswerId="5115" CreationDate="2014-05-27T19:23:38.540" Score="42" ViewCount="19217" Body="&lt;p&gt;The autopilot of an airplane is frequently referred to as &quot;George&quot; (for example, in &lt;a href=&quot;https://aviation.stackexchange.com/a/5076/909&quot;&gt;this answer&lt;/a&gt;). When did this nickname enter common usage, and what is its origin? Please cite sources if possible!&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-08-16T21:39:35.333" Title="Why is the autopilot called &quot;George?&quot;" Tags="&lt;autopilot&gt;&lt;terminology&gt;&lt;aviation-history&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5115" PostTypeId="2" ParentId="5114" CreationDate="2014-05-27T19:35:18.593" Score="42" Body="&lt;p&gt;The first &quot;practical&quot; autopilot was invented by George DeBeeson (&lt;a href=&quot;http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&amp;amp;Sect2=HITOFF&amp;amp;p=1&amp;amp;u=/netahtml/PTO/search-bool.html&amp;amp;r=1&amp;amp;f=G&amp;amp;l=50&amp;amp;d=PALL&amp;amp;RefSrch=yes&amp;amp;Query=PN/1829790&quot; rel=&quot;nofollow noreferrer&quot;&gt;the patent can be found here&lt;/a&gt;, updated &lt;a href=&quot;http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&amp;amp;Sect2=HITOFF&amp;amp;p=1&amp;amp;u=/netahtml/PTO/search-bool.html&amp;amp;r=1&amp;amp;f=G&amp;amp;l=50&amp;amp;d=PALL&amp;amp;RefSrch=yes&amp;amp;Query=PN/2146800&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;) - This seems to be the most likely reason for the informal name &quot;George&quot; for the autopilot system on aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autopilots are also sometimes called &quot;Otto&quot; (as in &lt;a href=&quot;https://www.youtube.com/watch?v=rQbj9uvYL8I&quot; rel=&quot;nofollow noreferrer&quot;&gt;Otto the Autopilot&lt;/a&gt; from &lt;em&gt;Airplane!&lt;/em&gt;, and &lt;a href=&quot;https://aviation.stackexchange.com/users/322/otto-the-autopilot&quot;&gt;our very own chat bot&lt;/a&gt;, but this seems to be less common than &quot;George&quot;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-05-27T19:35:18.593" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5116" PostTypeId="2" ParentId="5101" CreationDate="2014-05-27T21:58:31.307" Score="13" Body="&lt;p&gt;Trim is used to zero the stick forces at the desired flight condition, and with the small, slow early airplanes, an adjustable spring somewhere along the control cables would do. When speed increased, trim tabs were introduced, because their trim force goes up and down with dynamic pressure, whereas the spring would always create the same force. This would require re-adjustment with every speed change.&#xA;&lt;P&gt;&#xA;With the increasing size and speed of airplanes, manual control required ever more complicated means of force reduction (Flettner tabs, spring tabs), and the relative chord length of all moving surfaces shrank to allow for more control with less force. The moment around the hinge of a control surface increases with the square of the chord, but the lift change for a given deflection angle increases only with the square root of the chord.&#xA;&lt;P&gt;&#xA;In parallel, wing loadings increased, which required high-lift devices to keep take-off and landing speeds down. These add a lot of lift in the rear part of the wing, creating a strong nose-down moment, and now a simple control deflection would not suffice to trim the airplane. The reduced chord length meant that high deflection angles would have been required for trim, reaching far into the region of deflection angles with declining effectiveness. That is when adjustable stabilizers came up: The trim change with all configurations was simply too big to be covered by the elevator alone.&#xA;&lt;P&gt;&#xA;Transsonic flight was next, and here the adjustable tail incidence is crucial to trim the aircraft trough the transition from subsonic to supersonic flight. A contour break from a deflected elevator could cause shocks which could produce elevator reversal. The dynamic pressures of jet flight put an end to manual control - the last, famous examples were the Canberra or the Dash-8 (Boeing 707 prototype). Now hydraulic actuators were used, but still it makes sense to use aerodynamic means to reduce control forces, because the size and power requirements of the actuators can be reduced with clever hinge moment reduction. The trim tabs were initially moved by cables, but soon they used electric actuators.&lt;br&gt;&#xA;&lt;P&gt;&#xA;Since rudder and ailerons are not affected when the high-lift devices (Fowler flaps, slotted flaps) are deployed, they still use simple trim tabs. Newest developments are electric control surface actuators which can help to save mass and avoid the messy hydraulics. The RQ-4 uses electric actuators because the hydraulic fluid would have to be pumped continuously through the lines in order to keep it warm enough at the high operating altitude. Only the landing gear still uses hydraulics for retraction.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-11T03:42:17.493" LastActivityDate="2018-06-11T03:42:17.493" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="5117" PostTypeId="2" ParentId="5102" CreationDate="2014-05-27T22:46:35.783" Score="4" Body="&lt;p&gt;Hydraulics are used if you need to move something large quickly. Also, hydraulic actuators are perfect for linear motion, whereas electric motors are best for rotary motion. On the other hand, electric motors can be controlled more precisely: By counting the number of revolutions and the angle of the shaft, an electric motor can drive the trim spindle much more precisely than hydraulics, which move fluids into cylinders at high pressure. This does not (at least easily) allow for feedback on the position of the actuator, and only a limit switch can give easy position feedback.&#xA;&lt;P&gt;&#xA;In order to move a number of control surfaces, with hydraulics you need only one pump. Normally, only one surface is moved at a time, so it can use the full power of the pump. Together with a pressure reservoir, this allows for large forces &lt;strong&gt;and&lt;/strong&gt; large strokes. If you wanted to get the same control power with electric actuators, each control surface would need to have a big electric motor and gearbox next to it.&#xA;&lt;P&gt;&#xA;However, hydraulics are messy (can leak) and more maintenance-intensive than electric actuators. Hydraulics are less energy efficient (after all, all those lines create a lot of internal friction drag) and at low temperatures, the oil must be circulated continuously to keep it warm and &quot;runny&quot;. That is why electric actuators are now used in applications which had traditionally used hydraulics.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-05-27T22:46:35.783" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5118" PostTypeId="5" CreationDate="2014-05-28T05:08:38.157" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-05-28T05:08:38.157" LastActivityDate="2014-05-28T05:08:38.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5119" PostTypeId="4" CreationDate="2014-05-28T05:08:38.157" Score="0" Body="Aviation turbine fuel (ATF) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines (from Wikipedia)." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-05-28T11:49:01.253" LastActivityDate="2014-05-28T11:49:01.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5120" PostTypeId="2" ParentId="5114" CreationDate="2014-05-28T05:17:01.290" Score="-2" Body="&lt;p&gt;Perhaps from the Old Tyme Radio Show &quot;Let George Do It!&quot; wherein the hero hired himself out to do jobs too tough for his customers.&lt;/p&gt;&#xA;" OwnerUserId="2462" LastActivityDate="2014-05-28T05:17:01.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5121" PostTypeId="1" AcceptedAnswerId="5127" CreationDate="2014-05-28T08:35:12.613" Score="20" ViewCount="9784" Body="&lt;p&gt;I just played with flight simulator and noticed that the GPS shows different speed from the speed indicator in the cockpit. Also, GPS speed is higher than the Indicator. Any Idea why? &lt;/p&gt;&#xA;" OwnerUserId="2281" LastEditorUserId="487" LastEditDate="2014-05-28T19:26:59.310" LastActivityDate="2021-04-28T20:55:32.210" Title="Why is there a difference between GPS Speed and Indicator speed?" Tags="&lt;flight-instruments&gt;&lt;airspeed&gt;&lt;gnss&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5123" PostTypeId="2" ParentId="5121" CreationDate="2014-05-28T08:53:20.890" Score="3" Body="&lt;p&gt;Indicated airspeed is an approximation of the plane's speed in the air. Wind can cause the true airspeed to differ from ground speed (what the GPS shows).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To convert it to ground speed you need to know the wind speed and add them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\vec v_{air}+\vec v_{wind}=\vec v_{ground}$$&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-05-29T02:19:27.450" LastActivityDate="2014-05-29T02:19:27.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5124" PostTypeId="2" ParentId="5121" CreationDate="2014-05-28T10:01:01.173" Score="19" Body="&lt;p&gt;Here's a very simple graphic of what you could be seeing: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VN9OT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VN9OT.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.modelairplane.cadblog.net/images/airplane_airspeed_groundspeed.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;cadblog.net&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;And this is why we land into a headwind rather than the tailwind, since otherwise we would land at a faster speed and require more runway to stop.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;GPS measures ground speed, or absolute speed. The pitot tube on the aircraft will measure the speed relative to the airflow around the aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's som helpful graphic from NASA on &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/Animation/airrel/anrelg.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;relative velocity&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.grc.nasa.gov/www/k-12/airplane/Animation/airrel/Images/relg.gif&quot; alt=&quot;https://www.grc.nasa.gov/www/k-12/airplane/Animation/airrel/Images/relg.gif&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Footnote: As Ratchet Freak demonstrates in his equation, you have to of course remember that this is simplifying it as flying straight into the wind and not taking account of the wind direction.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-17T11:28:25.090" LastActivityDate="2019-03-17T11:28:25.090" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="5125" PostTypeId="1" AcceptedAnswerId="5133" CreationDate="2014-05-28T10:17:38.070" Score="3" ViewCount="362" Body="&lt;p&gt;I sometimes have the feeling that Airbus with augmented control are more prone to landing incidents (hard landings and runway excursions) than other models of aircraft with conventional controls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anywhere I could find data to perhaps back see if this might be correct? Such as a list of all landing incidents in Europe or the United States?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="167" LastEditDate="2014-05-29T18:52:27.737" LastActivityDate="2014-05-29T18:52:27.737" Title="Where can I get statistics on landing incidents?" Tags="&lt;safety&gt;&lt;incidents&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5126" PostTypeId="2" ParentId="5121" CreationDate="2014-05-28T11:48:13.300" Score="15" Body="&lt;p&gt;The other answers about wind are true, but this isn't what you're seeing in your simulation. What you're actually seeing is the difference between &lt;strong&gt;&lt;a href=&quot;http://en.m.wikipedia.org/wiki/True_airspeed&quot;&gt;true airspeed&lt;/a&gt;&lt;/strong&gt; and &lt;strong&gt;&lt;a href=&quot;http://en.m.wikipedia.org/wiki/Indicated_airspeed&quot;&gt;indicated airspeed&lt;/a&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;True airspeed is the plane's actual speed through the air. With no wind, this is the same as the plane's speed across the ground. This is what your GPS displays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airspeed indicator, on the other hand, is really just a &quot;dynamic pressure&quot; sensor. It works by measuring the pressure of the ram airflow. But as we know, as you climb up into the atmosphere, the air gets thinner - less dense, and lower pressure. This makes the airspeer indicator read lower than true airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason it's done this way is because all of the important aerodynamic stuff that can happen to a plane (like stalling) really is tied to dynamic pressure rather than true airspeed.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-05-28T11:54:57.530" LastActivityDate="2014-05-28T11:54:57.530" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5127" PostTypeId="2" ParentId="5121" CreationDate="2014-05-28T11:51:00.213" Score="52" Body="&lt;p&gt;The speed indicator in the cockpit shows &lt;em&gt;indicated airspeed&lt;/em&gt;. Indicated airspeed is usually different than GPS speed, due to wind and aerodynamic effects.&lt;/p&gt;&#xA;&lt;p&gt;GPS speed is your speed with respect to the ground. If you are standing on terra firma it reads 0. If it reads 100 knots you will be 100NM away from where you are now in one hour, so long as you keep flying in a straight line.&lt;/p&gt;&#xA;&lt;p&gt;Airspeed is the speed of the aircraft relative to the surrounding air. So if you are standing on terra firma with 20 knots wind blowing in your face, your airspeed will be 20 knots. If you travel at 100 knots airspeed against a 20 knots headwind wind, your ground speed is 80 knots. If you do 100 knots airspeed with 20 knots tailwind, your GPS speed reads 120 knots.&lt;/p&gt;&#xA;&lt;p&gt;But even in calm wind conditions the airspeed indicator will read differently than the GPS speed . This has to do with the way airspeed is measured.&lt;/p&gt;&#xA;&lt;p&gt;Airspeed is measured with a pitot tube. A pitot tube has two pressure measurement ports. One that measures the total pressure &lt;span class=&quot;math-container&quot;&gt;$P_t$&lt;/span&gt;. This port is facing the incoming airflow. The other measures the static pressure &lt;span class=&quot;math-container&quot;&gt;$P$&lt;/span&gt; and is placed perpendicular to the airflow. The difference between the two pressures is called impact pressure (pressure rise due to the airflow impacting the pitot tube) and is denoted &lt;span class=&quot;math-container&quot;&gt;$q_c$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The impact pressure is related to the speed of the airflow the pitot tube is exposed to. If the flow is considered incompressible (which is an acceptable approximation for speeds up to 200 knots) the impact pressure can be derived from Bernouilli's equation.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$q_c = \frac{1}{2}\rho V^2$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$q_c$&lt;/span&gt; is the impact pressure in Pa&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; is the density in kg/m&lt;sup&gt;3&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$V$&lt;/span&gt; is the true airspeed in m/s&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The airspeed indicator is calibrated for standard sea level conditions, where &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; is 1.225 kg/m&lt;sup&gt;3&lt;/sup&gt;. In reality the aircraft will fly at altitude and therefor the actual density of the air is lower. Therefor the &lt;em&gt;indicated airspeed&lt;/em&gt; will be lower as well. For example if an aircraft flies 75 m/s (about 146 knots) at 6000 ft the density will be 1.02393 kg/m&lt;sup&gt;3&lt;/sup&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$q_c = \frac{1}{2} 1.02393 \cdot 75 ^2 = 2879.8 \textrm{ Pa}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;The equivalent airspeed at sea level for the same &lt;span class=&quot;math-container&quot;&gt;$q_c$&lt;/span&gt; is:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{EAS} = \sqrt{\frac{2 q_c}{\rho_0}} = \sqrt{\frac{2 \cdot 2879.8}{1.225}} = 68.6 \textrm{ m/s}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Your airspeed indicator will read only 68.6 m/s (133 knots) despite the fact that you are moving with 75 m/s (146 knots) with respect to the air.&lt;/p&gt;&#xA;&lt;p&gt;Conversion of &lt;em&gt;true airspeed&lt;/em&gt; to the &lt;em&gt;equivalent airspeed&lt;/em&gt; can be done directly by:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{EAS} =V\cdot \sqrt{\frac{\rho}{\rho_0}}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{EAS}$&lt;/span&gt; equivalent airspeed (m/s)&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$V$&lt;/span&gt; true airspeed (m/s)&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; actual air density (kg/m&lt;sup&gt;3&lt;/sup&gt;).&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\rho_0$&lt;/span&gt; density at standard sea level conditions (1.225 kg/m&lt;sup&gt;3&lt;/sup&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The effects of the lower density on your aispeed indicator become more pronounced the higher you go. Once you go faster than about 100 m/s true airspeed the effects of compressibility can no longer be ignored and the above no longer applies. Airspeed indicators are corrected for effects of compressibility and therefore don't use the &lt;em&gt;equivalent airspeed&lt;/em&gt; but instead use &lt;em&gt;calibrated airspeed&lt;/em&gt; for calibration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{CAS}=a_{0}\sqrt{5\left[\left(\frac{q_c}{P_{0}}+1\right)^\frac{2}{7}-1\right]}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{CAS}$&lt;/span&gt; is calibrated airspeed&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$a_{0}$&lt;/span&gt; is the speed of sound under standard sea level conditions (340.3 m/s)&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$P_0$&lt;/span&gt; is the static air pressure under standard sea level conditions (101325 Pa)&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;${q_c}$&lt;/span&gt; is the impact pressure&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The impact pressure is also a bit more complex for compressible flow:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\;q_c = P\left[\left(1+0.2 M^2 \right)^\tfrac{7}{2}-1\right]$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$P$&lt;/span&gt; the static pressure&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$M$&lt;/span&gt; the Mach number&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Effectively, the higher and faster you get, the greater the difference between the indicated airspeed and the true airspeed.&#xA;For example, Mach 0.8 at 40000 ft in no wind will result in a GPS speed of &lt;strong&gt;489 knots&lt;/strong&gt;, but a calibrated airspeed of only &lt;strong&gt;242 knots&lt;/strong&gt;, which is less than half.&lt;/p&gt;&#xA;&lt;p&gt;Therefore at high altitudes and speeds, the indicated airspeed will be lower than the ground speed / GPS speed, unless you have extreme headwind.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="34686" LastEditDate="2021-04-28T20:55:32.210" LastActivityDate="2021-04-28T20:55:32.210" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="5128" PostTypeId="2" ParentId="5125" CreationDate="2014-05-28T14:21:30.970" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I ... feel ... [aircraft] with augmented control are more prone to landing incidents&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Airbus and Boeing 787 FBW with &lt;em&gt;augmented control&lt;/em&gt; have some similarities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This 2012 ICAS paper: &quot;&lt;a href=&quot;http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/605.PDF&quot; rel=&quot;nofollow&quot;&gt;FLY-BY-WIRE AUGMENTED MANUAL CONTROL - BASIC DESIGN&#xA;CONSIDERATIONS&lt;/a&gt;&quot; discusses Boeing and Airbus &lt;em&gt;augmented control&lt;/em&gt; systems and its effect on piloting technique&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See 4.2.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;4.2 Piloting Technique for Disturbance Compensation&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;The influence of manual &lt;em&gt;augmented control&lt;/em&gt; on the optimal&#xA;  piloting technique is significant. For conventionally&#xA;  controlled aircraft the task of stabilizing the&#xA;  aircraft on the desired flight path after an external disturbance&#xA;  is left to the pilot, but the pilot has no suitable&#xA;  indication of flight path deviation on his PFD. For&#xA;  that reason pilots are still used to react to a change of&#xA;  attitude angles. As the attitude angles are easy to derive&#xA;  either from the outside view or from the PFD that&#xA;  puts the main focus on the aircraft attitude control, the&#xA;  main control references for manual control are still the&#xA;  pitch angle for longitudinal control and the bank angle&#xA;  for lateral control.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, the application of manual augmented control&#xA;  in modern FBW aircraft has influenced the distribution&#xA;  of tasks between the pilot and the flight control&#xA;  system with respect to the compensation for external&#xA;  disturbances.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For lateral motion control, Airbus uses a roll rate command&#xA;  and bank angle hold system which actively tries&#xA;  to keep the bank angle at zero after a lateral disturbance.&#xA;  The B777 FBW lateral control is basically a&#xA;  Direct Control mode without feedbacks and a roll attitude&#xA;  hold feature, so the airplane responds to a lateral&#xA;  disturbance like a conventionally controlled airplane.&#xA;  &lt;strong&gt;The B787 has an integrated lateral/directional control&#xA;  algorithm that provides basically roll rate command/&#xA;  roll attitude hold control, similar to the Airbus design.&lt;/strong&gt;&#xA;  The latter type of designs provide more roll attitude&#xA;  stiffness and thus require less pilot compensation for&#xA;  external disturbances. For those control algorithms a&#xA;  strong reaction of the pilot in response to rotational&#xA;  rates or attitude angle changes might lead to adverse&#xA;  effects due to a significant interaction between pilot&#xA;  and the flight control algorithm.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In 2010 DLR performed a study on a Airbus A330&#xA;  Full Flight Simulator, where the aircraft was disturbed&#xA;  by a simulated wake vortex encounter while the pilots&#xA;  revealed&#xA;  that numerous pilots aggravated the impact of&#xA;  the wake vortex on the aircraft response by generating&#xA;  to strong and to abrupt inputs on the stick, although&#xA;  they were informed that a wake encounter could occur&#xA;  [23]. This was especially observed for pilots with&#xA;  little experience on FBW aircraft. The final report&#xA;  recommends that the pilots should react to the lateral&#xA;  and vertical flight path deviation with extremely&#xA;  smooth inputs on the stick rather than trying to overcompensate&#xA;  for the change in attitude angles [23].&#xA;  These recommendations are similar to those given&#xA;  by Airbus for manual control during wake-vortex encounters&#xA;  [21].&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Hence, the piloting technique should change from a&#xA;  continuous compensatory control to an intermittent&#xA;  control strategy, because the short-term control task&#xA;  of continuous pitch and roll attitude stabilization is&#xA;  performed by the control algorithm. In many current&#xA;  airline training programs no emphasis is put on the&#xA;  adaptation of the piloting technique that is needed to&#xA;  safely operate a FBW aircraft with manual augmented&#xA;  control in case of external disturbances. It seems that&#xA;  in most cases the pilot still uses pitch angle as his primary&#xA;  control variable. During the simulator study performed&#xA;  by Gautrey &lt;strong&gt;several pilots commented on the&#xA;  desirability of a flight path vector display&lt;/strong&gt;, especially&#xA;  for the unconventional systems without speed stability,&#xA;  because this is the parameter which they are ultimately&#xA;  trying to control [12]. &lt;strong&gt;For the majority of existing&#xA;  Airbus FBW aircraft the flight path vector symbol&#xA;  is only available in the PFD, if certain autopilot&#xA;  modes are triggered. However, flight path information&#xA;  is displayed in the head-up display which can be&#xA;  optionally ordered for every Airbus FBW aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-05-28T14:36:50.523" LastActivityDate="2014-05-28T14:36:50.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5129" PostTypeId="2" ParentId="5073" CreationDate="2014-05-28T15:14:37.643" Score="7" Body="&lt;p&gt;There is no term (that I am aware of) referring to only the portion of the takeoff while the tail is off the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the attitude where just the two main wheels are touching the ground is called &quot;two-point.&quot; Likewise, with the tail wheel also on the ground, it is called &quot;three-point.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, a two-point landing is sometimes called a &quot;wheel landing&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.richstowell.com/services/tailwheel-training/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-21T17:38:59.937" LastActivityDate="2015-02-21T17:38:59.937" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5130" PostTypeId="2" ParentId="5068" CreationDate="2014-05-28T15:22:51.783" Score="12" Body="&lt;p&gt;In addition to Rachet Freak answer I'll add that helicopter engines are subject to much dirtier air. Aircraft operate from runways which are relatively clean. Due to their speed, most dust and debris that is kicked up is behind the engine inlet so it is not sucked in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tzG57.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters hover and land vertically and therefore their engines ingest air contaminated with kicked up dust. Especially when operating outside paved surfaces this results in considerable pollution. A filter is much more useful here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zq6a2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yUtB8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-05-28T15:22:51.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5131" PostTypeId="1" CreationDate="2014-05-28T18:27:20.127" Score="36" ViewCount="4573" Body="&lt;p&gt;How difficult is it to hand-fly a jet at cruise altitudes? Other than autopilot failure and just doing it for the fun of it, when might you want to hand-fly at those altitudes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect the answer to the first question varies with different aircraft. I have an answer for the 747-100 and -200 series below.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1696" LastEditDate="2015-02-20T23:14:58.633" LastActivityDate="2016-03-11T17:03:44.660" Title="When might a pilot hand-fly a jet at cruise altitudes, and is it difficult?" Tags="&lt;flight-controls&gt;&lt;jet&gt;&lt;pilot-technique&gt;&lt;cruise&gt;&lt;rvsm&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5132" PostTypeId="2" ParentId="5131" CreationDate="2014-05-28T18:27:20.127" Score="34" Body="&lt;p&gt;For 747-100 and -200 aircraft at 35,000 ft and above, you can do it, but it's hard to keep the airplane within 100 feet of the assigned altitude, and you typically can't do that (or at least I couldn't) without practice. 200 foot altitude excursions were the norm when I first took control if I had not done it for a while. For the few first officers that accepted an invitation to try it, an initial 300 foot altitude excursion was typical when they first tried it, especially immediately after disengaging the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found the concentration required was very tiring. Ten minutes was typically enough to satisfy the urge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insofar as when you might want to do it, I found hand-flying produced a smoother ride in heavy to severe turbulence than the autopilot's turbulence mode, which tended to try to keep the assigned altitude and aircraft pitch too slavishly.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="938" LastEditDate="2014-05-28T19:27:18.057" LastActivityDate="2014-05-28T19:27:18.057" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5133" PostTypeId="2" ParentId="5125" CreationDate="2014-05-28T18:59:58.983" Score="1" Body="&lt;p&gt;NASA collects statistics on aviation incidents through its Aviation Safety Reporting System, and the &lt;a href=&quot;http://asrs.arc.nasa.gov/search/database.html&quot; rel=&quot;nofollow&quot;&gt;ASRS database&lt;/a&gt; is searchable online.  You can specify criteria such as the flight phase and aircraft type in your search.&lt;/p&gt;&#xA;" OwnerUserId="487" LastActivityDate="2014-05-28T18:59:58.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5134" PostTypeId="2" ParentId="5131" CreationDate="2014-05-28T19:35:57.803" Score="12" Body="&lt;p&gt;It's probably not a good idea to hand fly jets at cruise altitudes in many cases (&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/rvsm/documentation/#large&quot; rel=&quot;nofollow noreferrer&quot;&gt;US&lt;/a&gt;, &lt;a href=&quot;http://www.skybrary.aero/index.php/Reduced_Vertical_Separation_Minima_%28RVSM%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;EU&lt;/a&gt;, and others). The reason is that from FL290 to FL410 (29,000 to 41,000 feet standard pressure altitude), a lot of airspace is under &lt;a href=&quot;http://en.wikipedia.org/wiki/Reduced_vertical_separation_minima&quot; rel=&quot;nofollow noreferrer&quot;&gt;RVSM&lt;/a&gt; rules (Reduced vertical separation minima).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that aircraft are only separated by 1000 feet vertically. One of the requirements for flying in RVSM airspace is a system for automatically maintaining altitude. If this system is not working, either the aircraft must fly at an altitude outside RVSM space (most likely below) or ATC must agree to provide 2000 foot separation above and below from other traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples of this in practice:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=45237903&quot; rel=&quot;nofollow noreferrer&quot;&gt;Allowed to continue with increased separation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=463e0a88&quot; rel=&quot;nofollow noreferrer&quot;&gt;Not allowed to continue, had to return to airport&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=4694c940&quot; rel=&quot;nofollow noreferrer&quot;&gt;Did not inform ATC in violation of rules&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See the related question for more details:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/153/is-it-legal-to-fly-in-rvsm-airspace-with-an-inoperative-autopilot&quot;&gt;Is it legal to fly in RVSM airspace with an inoperative autopilot?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-05-28T19:35:57.803" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5135" PostTypeId="2" ParentId="5070" CreationDate="2014-05-28T20:26:17.150" Score="4" Body="&lt;p&gt;If you want data from small aircraft, &lt;a href=&quot;http://cirrusreports.com&quot; rel=&quot;nofollow&quot;&gt;cirrusreports.com&lt;/a&gt; has data recorder information for thousands of flights. I don't believe you can actually download the raw data, but you can interactively plot dozens of parameters.&lt;/p&gt;&#xA;" OwnerUserId="4" LastActivityDate="2014-05-28T20:26:17.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5136" PostTypeId="2" ParentId="5131" CreationDate="2014-05-28T20:57:48.260" Score="10" Body="&lt;p&gt;Aerodynamic damping is proportional to density, so all maneuvers require less control input at altitude than near the ground. On the downside, excursions from the trimmed condition produce greater amplitudes before stability pulls the aircraft back. This explains why hand-flying needs more attention at high altitude.&#xA;&lt;P&gt;&#xA;Background: Damping is the reaction of a system to movement, and positive damping means the reaction slows the movement down. Case in point: The horizontal tail. When the pitch attitude changes (say, by a vertical gust which changes lift first on the wing, then on the horizontal tail), the rotation of the aircraft around the Y axis (the one pointing sideways) creates an additional vertical speed on the horizontal tail surface. This vertical speed is proportional to pitch speed (obviously) and the distance between c.g. and tail. This speed changes the local angle of attack by the ratio between the vertical speed and flight speed. Now we are at the core of it: A high flight speed will cause a smaller angle of attack change at the tail for the same pitch rate. Since this angle of attack change creates the damping force (by creating lift on the tail which counteracts the pitch movement), a higher flight speed at the same dynamic pressure will lead to less damping. This is a fancy way of saying that flying in lower density air makes the aircraft more responsive to disturbances.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-05-29T16:05:57.770" LastActivityDate="2014-05-29T16:05:57.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5137" PostTypeId="1" AcceptedAnswerId="5138" CreationDate="2014-05-29T10:27:03.637" Score="6" ViewCount="4345" Body="&lt;p&gt;What is difference between &quot;active&quot; and &quot;passive&quot; sidestick?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which aircraft have active sidestick?&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="6919" LastEditDate="2015-04-28T02:01:20.213" LastActivityDate="2017-08-12T09:58:43.620" Title="What is the difference between active and passive sidestick?" Tags="&lt;flight-controls&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5138" PostTypeId="2" ParentId="5137" CreationDate="2014-05-29T13:06:52.507" Score="6" Body="&lt;p&gt;For references, I've used &lt;a href=&quot;http://www.freepatentsonline.com/y2008/0156939.html&quot; rel=&quot;noreferrer&quot;&gt;United States Patent Application 20080156939&lt;/a&gt;; &lt;a href=&quot;http://www.ainonline.com/aviation-news/farnborough-air-show/2012-07-10/bae-systems-develops-civil-aircraft-active-control-stick&quot; rel=&quot;noreferrer&quot;&gt;BAE Systems Develops Civil Aircraft Active Control Stick&lt;/a&gt;; &lt;a href=&quot;http://www.researchgate.net/publication/3519627_Active_and_passive_side_stick_controllers_in_manual_aircraftcontrol&quot; rel=&quot;noreferrer&quot;&gt;Active and passive side stick controllers in manual aircraft control&lt;/a&gt;; &amp;amp; the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sidestick&quot; rel=&quot;noreferrer&quot;&gt;Side-stick wiki entry&lt;/a&gt;. The wiki is a general side-stick discussion listing (some) aircraft that have side-stick fly-by-wire (FBW) technology, but does not go into active vs. passive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, if you have used a joystick on your PC to fly Microsoft's Flight Simulator, such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Microsoft_SideWinder&quot; rel=&quot;noreferrer&quot;&gt;Microsoft's Force-Feedback Sidewinder Pro&lt;/a&gt;, you've used an active side-stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the Patent Application cited above, the patent is for an Active Side-Stick technology described as &quot;pilot flight control stick haptic feedback mechanism provides variable force feedback to the pilot flight control stick.&quot; One of the 'issues' with the current passive side-stick technology (approved for use) used on aircraft such as Airbus' A380 is that there is no tactile feedback when using the side-sticks, such as a pilot would feel using an old-style column or yoke. In a Cessna 172, for instance, when you pull/push/turn the yoke, there is actual tactile feel, if you pull back strongly in-flight, you'll 'feel' the forces exerted against the airflow. Passive side-sticks have none of this 'feel'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active SS technology attempts to replicate the forces on the joystick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active SS technology is currently used on most miltary aircraft using side-sticks, but does not appear to have yet made its way into civilian airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If I've gotten stuff wrong, I'll remove/fix this answer, as I am not an airline pilot and have never had the opportunity to fly military hardware.)&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-05-29T13:06:52.507" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5139" PostTypeId="1" AcceptedAnswerId="5142" CreationDate="2014-05-29T15:24:29.980" Score="16" ViewCount="6149" Body="&lt;p&gt;I live near the Cleveland International Airport. &lt;a href=&quot;https://www.google.com/maps/@41.41895,-81.847977,3a,75y,141.21h,91.09t/data=!3m4!1e1!3m2!1siLLPgcIIHD3kbChuycm7qw!2e0&quot; rel=&quot;noreferrer&quot;&gt;I have a Quadrocopter and the fence doesn't seem to be very high.&lt;/a&gt; I could probably fly my quadcopter into the airport. Is this legal? Can I crash a plane with it? Is this a new terrorist attack vector? Will the airport security try to jam radio signals or something? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is just a hypothetical question. I do not intend to wreak havoc and crash planes.&lt;/p&gt;&#xA;" OwnerUserId="1006" LastEditorUserId="1006" LastEditDate="2015-11-27T05:17:43.427" LastActivityDate="2015-11-27T11:26:19.750" Title="What damage can occur and what penalties will you face for flying a quad rotor into a restricted airspace?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;airport&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5140" PostTypeId="2" ParentId="5139" CreationDate="2014-05-29T15:54:02.213" Score="1" Body="&lt;p&gt;Intruding in an airport's controlled airspace (typically class B or C airspace) or endangering an airplane is illegal. (This includes non physical interference.) Doing this as a pilot in a plane can get your license suspended by the FAA and NTSB.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the tower sees unauthorized entry of a drone they will clear the airspace and send security to catch the guy controlling it.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-05-29T18:22:24.983" LastActivityDate="2014-05-29T18:22:24.983" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="5141" PostTypeId="2" ParentId="5139" CreationDate="2014-05-29T15:58:28.567" Score="9" Body="&lt;p&gt;First off, it is VERY important to note that you DON'T fly a Drone. RC Model Aircraft are flown by hobbiests, and Drones are flown by the government. It is enumbant on all of us R/C modelers to enforce that at all times, lest the government decide that all R/C hobbiest model aircraft be banned.&lt;/p&gt;&#xA;&lt;p&gt;(I am making an assumption that you aren't doing this as a member of the armed forces, or working for the government, also my comments are US oriented.)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;FAA Modernization and Reform Act of 2012&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Senate Bill, Section 607(g) …exempts most model airplanes used for recreational or academic use from any UAS regulations established by the FAA&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Conference Committee Report&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Senate bill with modifications… &lt;em&gt;Language including model aircraft for the purposes of sports, competitions and academic purposes is removed and replaced with &amp;quot;hobby&amp;quot;. The modified section includes language requiring that the model aircraft must be operated in a manner that does not interfere with and gives way, to all manned aircraft. In addition, language that requires that model aircraft flown within five miles of an airport will give prior notification to the airport and the air traffic control (ATC), and that model aircraft that are flown consistently within five miles of the ATC will do so under standing agreements with the airports and ATC. Lastly, language is added that will ensure that nothing in this provision will interfere with the Administrator's authority to pursue enforcement action against persons operating model aircraft who endanger the safety of the national airspace system. In this section the term &amp;quot;nationwide community-based organization&amp;quot; is intended to mean a membership based association that represents the aeromodeling community within the United States; provides its members a comprehensive set of safety guidelines that underscores safe aeromodeling operations within the National Airspace System and the protection and safety of the general public on the ground; develops and maintains mutually supportive programming with educational institutions, government entities and other aviation associations; and acts as a liaison with government agencies as an advocate for its members.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;SEC. 336. SPECIAL RULE FOR MODEL AIRCRAFT.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(a) In General.&lt;/strong&gt; --Notwithstanding any other provision of law relating to the incorporation of unmanned aircraft systems into Federal Aviation Administration plans and policies, including this subtitle, the Administrator of the Federal Aviation Administration may not promulgate any rule or regulation regarding a model aircraft, or an aircraft being developed as a model aircraft, if--&lt;/p&gt;&#xA;&lt;p&gt;(1) the aircraft is flown strictly for hobby or recreational use;&lt;/p&gt;&#xA;&lt;p&gt;(2) the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;&lt;/p&gt;&#xA;&lt;p&gt;(3) the aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization;&lt;/p&gt;&#xA;&lt;p&gt;(4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft; and&lt;/p&gt;&#xA;&lt;p&gt;(5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation (model aircraft operators flying from a permanent location within 5 miles of an airport should establish a mutually-agreed upon operating procedure with the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport)).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(b) Statutory Construction.&lt;/strong&gt; --Nothing in this section shall be construed to limit the authority of the Administrator to pursue enforcement action against persons operating model aircraft who endanger the safety of the national airspace system.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(c) Model Aircraft Defined.&lt;/strong&gt; --In this section, the term &amp;quot;model aircraft&amp;quot; means an unmanned aircraft that is--&lt;/p&gt;&#xA;&lt;p&gt;(1) capable of sustained flight in the atmosphere;&lt;/p&gt;&#xA;&lt;p&gt;(2) flown within visual line of sight of the person operating the aircraft; and&lt;/p&gt;&#xA;&lt;p&gt;(3) flown for hobby or recreational purposes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;When this law is passed, you'll need to contact the airport tower/operator if you intend on flying your model aircraft within 5 miles of the airport.&lt;/p&gt;&#xA;&lt;p&gt;If, at the time of this answer, the law has not yet passed, the rules prior were to keep your model aircraft under 400ft AGL within 3 miles of an airport. Flying your model aircraft over the boundary fence OF an airport is considered tresspassing and an incursion.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-05-29T15:58:28.567" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="5142" PostTypeId="2" ParentId="5139" CreationDate="2014-05-29T15:59:06.720" Score="13" Body="&lt;p&gt;The legal issues are &lt;a href=&quot;https://aviation.stackexchange.com/questions/2850/where-is-rc-aircraft-flying-allowed-in-the-us&quot;&gt;covered in another question&lt;/a&gt;. The FAA doesn't currently regulate recreational model aircraft operations, which includes quadcopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were you to actually fly it over the fence, you could be &lt;a href=&quot;http://www.volokh.com/2012/02/19/private-drones-and-private-property-rights/&quot; rel=&quot;nofollow noreferrer&quot;&gt;charged with trespassing&lt;/a&gt;. If you had any intent to cause harm, other charges might apply (up to attempted murder if you were trying to bring down an airliner).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can I crash a plane with it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not likely. If you flew the quadcopter into a jet engine intake, you might be able to shut down the engine (similar to &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow noreferrer&quot;&gt;ingestion of a bird&lt;/a&gt;). This would really annoy the flight crew but would normally not result in a crash. A strike in any other place is probably going to merely dent something on the plane, and utterly destroy your quadcopter. For a small plane, &lt;a href=&quot;http://www.wildlifedamagecontrol.net/images/birds/birdstrike/1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;shattering the windshield&lt;/a&gt; is a possibility, and this would be a serious hazard that could cause a crash, but is quite unlikely. Without some kind of advanced guidance system, it's going to be very hard to hand-fly the copter into a plane at all, let alone precisely target a vulnerable point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bottom line, though, is &lt;strong&gt;don't do it&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this a new terrorist attack vector?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Maybe!&lt;/strong&gt; The use of unmanned aerial systems by terrorists is a subject of concern and research in the defense community. The &lt;a href=&quot;http://www.rand.org/&quot; rel=&quot;nofollow noreferrer&quot;&gt;RAND Institute&lt;/a&gt; has &lt;a href=&quot;http://www.rand.org/pubs/monographs/MG626.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;published a whole book about it&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drones are already being &lt;a href=&quot;http://newstalk870.am/mexican-drug-cartels-using-drones-to-scout-border-crossings/&quot; rel=&quot;nofollow noreferrer&quot;&gt;used by drug cartels to smuggle drugs across borders&lt;/a&gt;. There have also been some high-profile incidents where terrorists were able to tamper with, and in at least one case eavesdrop on, a U.S. military drone by &lt;a href=&quot;http://online.wsj.com/news/articles/SB126102247889095011&quot; rel=&quot;nofollow noreferrer&quot;&gt;obtaining and decoding its live video feed&lt;/a&gt;. I don't know of any publicized instances of someone intentionally causing damage with a UAV or model airplane, but I'm sure the terrorists are thinking about it.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-05-29T16:23:37.923" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5143" PostTypeId="1" CreationDate="2014-05-29T18:53:56.817" Score="19" ViewCount="1486" Body="&lt;p&gt;Can pilots with color deficient eyesight expect to see the red, green, and white light-gun signals as such? In other words, if the controller is giving them a green light, will they see green? If they are being given a white light, will they see white?&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-29T18:53:56.817" Title="Do pilots who have color deficient eyesight see light gun signals differently?" Tags="&lt;air-traffic-control&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5144" PostTypeId="2" ParentId="5143" CreationDate="2014-05-29T18:53:56.817" Score="20" Body="&lt;p&gt;It depends on the type and severity of the color deficiency and on the individual. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I first applied for a 2nd class medical, I couldn't pass the color test. I took a practical test with an FAA inspector to get a waiver. We walked outside the FSDO office, and he had me identify the color of the lights being directed at me by the tower. Fortunately, I had been warned to have the tower do this for me on a previous day so I wouldn't be surprised. In my case I had to remember that if I saw yellow, that was white. If I saw white, that was green. Red was red.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I first applied for a 1st class medical, I again had to take a practical test, but this time from an airplane. I noticed that from the airplane, the white of the green signal was more white, and the yellow of the white signal was more yellow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether the difference from the ground test was due to the increased distance or to my individual daily variation I don't know. I have noticed during physicals through the years that my performance on the color test varies greatly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion every pilot should have the tower shoot light-gun signals at him during training so that she/he can see how they look.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-05-29T18:53:56.817" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5145" PostTypeId="2" ParentId="5065" CreationDate="2014-05-29T19:04:41.480" Score="10" Body="&lt;p&gt;I think you've got your terminology crossed here (but it's not your fault - your sources don't seem to clear on it either).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Hang_gliding&quot; rel=&quot;nofollow&quot;&gt;hang glider&lt;/a&gt; is by definition a solar vehicle: They're non-motorized, and the pilot keeps them aloft by seeking thermal lift (created by the sun shining on the ground and heating it up) or ridge lift (created by wind striking the side of a mountain/hill (ridge) and being deflected up.&lt;br&gt;&#xA;Both of these rely on the sun (either directly heating the local ground, or unevenly heating various parts of the Earth's surface, ultimately creating wind).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you're referring to would be a solar-powered ultralight aircraft -- basically a hang glider with a motor strapped to it, or possibly an electric &lt;a href=&quot;http://en.wikipedia.org/wiki/Powered_paragliding&quot; rel=&quot;nofollow&quot;&gt;powered paraglider&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One could conceivably create a solar-powered ultralight &lt;a href=&quot;http://www.mothsworld.com/solar-powered-paramotor.asp&quot; rel=&quot;nofollow&quot;&gt;using flexible solar cells on the wing&lt;/a&gt;  - &lt;s&gt;in fact a little Googling reveals that &lt;a href=&quot;http://www.parajetusa.com/expeditions/cat/solar-electric-flight/&quot; rel=&quot;nofollow&quot;&gt;it has apparently been done&lt;/a&gt; with an electric paramotor (a type of powered parachute)&lt;/s&gt; (A little more Googling reveals this wasn't as cool as I previously thought - they seem to have been using a support vehicle to recharge their battery packs (with solar cells).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I'm aware no such vehicle is commercially available at this time (May 2014), but the materials and technology to construct such a vehicle are certainly available (the folks over at the &lt;a href=&quot;http://www.eaa.org&quot; rel=&quot;nofollow&quot;&gt;Experimental Aircraft Association&lt;/a&gt; could probably provide guidance on building something like this), and it wouldn't surprise me if commercial or kit-build solar ultralights become available at some point in the future.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-05-31T18:36:03.733" LastActivityDate="2014-05-31T18:36:03.733" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5146" PostTypeId="1" AcceptedAnswerId="5147" CreationDate="2014-05-29T20:38:31.083" Score="7" ViewCount="1243" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6SN6O.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6SN6O.jpg&quot; alt=&quot;Two mandatory holding points at LFPG 08L&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I learned that red signs mean: full stop is mandatory.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do aircraft have to stop before CAT III 08L sign AND before CATI 26R-08L sign?&lt;/li&gt;&#xA;&lt;li&gt;What is the purpose of making two stops? &lt;/li&gt;&#xA;&lt;li&gt;Is the area between these two mandatory stops special?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2452" LastEditorUserId="1696" LastEditDate="2015-09-22T14:15:51.257" LastActivityDate="2015-09-22T14:51:28.943" Title="What is the purpose of several mandatory stops (RWY AHEAD) at busy airports?" Tags="&lt;runways&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5147" PostTypeId="2" ParentId="5146" CreationDate="2014-05-29T20:59:38.400" Score="12" Body="&lt;p&gt;A full stop at a red sign is only mandatory if ATC has not given you explicit clearance to proceed further. Aircraft will be instructed to &quot;hold short&quot; of the runway, and these signs indicate where the aircraft should stop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CAT II/III signs are only for holding when CAT II/III operations are active on that runway. This refers to categories of the Instrument Landing System (ILS) that are currently in use. An aircraft only needs to stop at the sign applicable for the current conditions, as instructed by ATC. Generally if an aircraft must stop at the CAT III holding point, they will later be cleared either to take off or line up and wait on the runway. That clearance means they do not need to also stop at the CAT I point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On page 47 of this &lt;a href=&quot;//www.icao.int/safety/Implementation/Library/Manual%20Aerodrome%20Stds.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO Aerodrome Standards&lt;/a&gt; manual there is a table showing the required distances from runway center line for holding positions. For example, a long runway (code 4) would require 75 m normal distance, and 90 m for CAT I/II/III approaches. These numbers increase with runway altitudes over 700 m (2,300 ft) elevation. There are also many other factors in the airport configuration that might require a greater distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The different holding points are to ensure that in lower visibility conditions, there is more room for added safety. It also helps to ensure that holding aircraft do not interfere with the &lt;a href=&quot;//aviation.stackexchange.com/q/2620/1696&quot; rel=&quot;nofollow&quot;&gt;precision approach signals&lt;/a&gt;. The CAT III holding point is further from the runway to ensure that the guidance equipment will provide CAT III accuracy and avoid interference from aircraft and vehicles. If there is not a clear procedure in effect to keep these areas clear, interference can happen, and the faulty signals can result in the airplane &lt;a href=&quot;//avherald.com/h?article=47260f32&quot; rel=&quot;nofollow&quot;&gt;following an incorrect path&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-09-22T14:51:28.943" LastActivityDate="2015-09-22T14:51:28.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5148" PostTypeId="1" AcceptedAnswerId="5151" CreationDate="2014-05-29T23:31:44.807" Score="23" ViewCount="3337" Body="&lt;p&gt;Do (GA) pilots necessarily have to plan every flight, or can someone just go up and fly? Please note I don't mean actually 'filing a flight plan', but does every flight need to be carefully plotted out in advance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can get in my car and just drive. If I really wanted to, I could point its nose West and drive until I wanted to stop. In the first years of flight, like during the barn-storming era, a pilot with a plane could hop in and fly as long as he had gas, it seems like there is less enjoyment of &quot;flying for flying's sake&quot; and more 400 hours of planning for a 4 hour trip.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-05-31T06:20:27.607" Title="Are all flights planned?" Tags="&lt;flight-planning&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5149" PostTypeId="2" ParentId="5148" CreationDate="2014-05-29T23:44:00.210" Score="17" Body="&lt;p&gt;It is not necessary to create a detailed plotted flight plan for every flight. However, a pilot is required to ensure that they are able to safely land the aircraft in case of an emergency (including engine failure) at any time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is generally not a problem if the pilot is familiar with the area (such as around their local airport or a frequently flown route). However, if the pilot is intending to fly in an unfamiliar area, they will want to do some research beforehand to find out information about things like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;nearby airfields&lt;/li&gt;&#xA;&lt;li&gt;airspace designations&lt;/li&gt;&#xA;&lt;li&gt;terrain (mountains)&lt;/li&gt;&#xA;&lt;li&gt;obstacles (antennas)&lt;/li&gt;&#xA;&lt;li&gt;restricted and prohibited areas&lt;/li&gt;&#xA;&lt;li&gt;temporary flight restrictions (TFRs)&lt;/li&gt;&#xA;&lt;li&gt;weather forecast&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In some jurisdictions, the pilot is also required to carry official charts for their intended area of flight. The rules can't force the pilot to read them, but if anything goes wrong the investigators will check to make sure they're present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During flight training, students are usually required to create a detailed flight plan for a flight.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="675" LastEditDate="2014-05-29T23:50:50.577" LastActivityDate="2014-05-29T23:50:50.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5150" PostTypeId="1" CreationDate="2014-05-29T23:59:42.657" Score="12" ViewCount="11870" Body="&lt;p&gt;I would like to know the angle of attack that a 737 flies at during cruise. I am specifically interested in the wing angle of attack (if you know the cruise nose-up attitude and the wing incidence angle, that would be good too).&lt;/p&gt;&#xA;" OwnerUserId="2456" LastEditorUserId="97" LastEditDate="2015-05-03T01:57:13.970" LastActivityDate="2019-02-15T14:28:35.607" Title="What is the wing angle of attack of a Boeing 737 in cruise?" Tags="&lt;boeing-737&gt;&lt;cruise&gt;&lt;angle-of-attack&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5151" PostTypeId="2" ParentId="5148" CreationDate="2014-05-30T01:52:50.730" Score="25" Body="&lt;p&gt;You didn't specify the jurisdiction that you were asking about, but in the US there is a regulation that covers the minimum that you must do before flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much of it is common sense:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You want to check the weather, because it can impact you much more than it usually does in your car and you don't want to get stuck in a really bad situation.  &lt;/li&gt;&#xA;&lt;li&gt;You want to check the Notices to Airmen (NOTAMs) to make sure that you can use the airport (i.e. it isn't closed, or the runway isn't closed, etc.)&lt;/li&gt;&#xA;&lt;li&gt;You want to make sure that you have enough fuel, because you can't just pull over at the nearest gas station when you get low.  &lt;/li&gt;&#xA;&lt;li&gt;You want to make sure that the runways are long enough and that the airplane can climb well enough so that you don't crash into something.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That being said, if you are familiar with the area and the airports in the area, you have used them before and are already familiar with the performance numbers for your airplane, then you don't really need to do much more than check the weather/NOTAMs and make sure that your airplane is legal and safe to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things are a little different than back in the barnstorming days, but then there are fewer accidents too.  :-)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.2.4.2&quot;&gt;§91.103   Preflight action.&lt;/a&gt;&lt;br&gt;&#xA;  Each pilot in command shall, before&#xA;  beginning a flight, become familiar with all available information&#xA;  concerning that flight. This information must include—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) For a flight under IFR or a flight not in the vicinity of an&#xA;  airport, weather reports and forecasts, fuel requirements,&#xA;  alternatives available if the planned flight cannot be completed, and&#xA;  any known traffic delays of which the pilot in command has been&#xA;  advised by ATC;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For any flight, runway lengths at airports of intended use, and&#xA;  the following takeoff and landing distance information:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) For civil aircraft for which an approved Airplane or Rotorcraft&#xA;  Flight Manual containing takeoff and landing distance data is&#xA;  required, the takeoff and landing distance data contained therein; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For civil aircraft other than those specified in paragraph (b)(1)&#xA;  of this section, other reliable information appropriate to the&#xA;  aircraft, relating to aircraft performance under expected values of&#xA;  airport elevation and runway slope, aircraft gross weight, and wind&#xA;  and temperature.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-05-31T06:20:27.607" LastActivityDate="2014-05-31T06:20:27.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5152" PostTypeId="1" AcceptedAnswerId="5156" CreationDate="2014-05-30T04:45:34.380" Score="15" ViewCount="16661" Body="&lt;p&gt;While browsing &lt;a href=&quot;https://aviation.stackexchange.com/a/2884/558&quot;&gt;this answer&lt;/a&gt; I noticed the sheepskin cover and recalled that I couldn't remember a cockpit that didn't have them. It's not entirely surprising that they're used, but I am surprised that they seem to be always used. Are they indeed ubiquitous? Are there any competing alternatives? Do modern airliners use them as much as GA/military/sport aircraft?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-05-30T15:55:04.360" Title="Why do pilots' seat covers almost uniformly use sheepskin?" Tags="&lt;cockpit&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5153" PostTypeId="2" ParentId="5150" CreationDate="2014-05-30T05:14:20.600" Score="10" Body="&lt;p&gt;First, let's assume that all lift is created by the wing, and that the plane is flying in ideal conditions, where fuel flow per distance flown is minimal. This point is given by $$c_L = \sqrt{\frac{1-n_v}{3+n_v}\cdot c_{D0} \cdot \pi \cdot AR \cdot \epsilon}$$ Please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;this post&lt;/a&gt; for more background on this formula.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient&lt;br&gt;&#xA;    $n_v \:\:\:$  thrust exponent, as in $T \sim v^{n_v} $&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The $n_v$ I would estimate to be -0.4, the $c_{D0}$ is somewhere around 0.016, the aspect ratio can be taken from &lt;a href=&quot;http://www.b737.org.uk/techspecsdetailed.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this source&lt;/a&gt; and the Oswald factor is 0.8. This gives you an optimum lift coefficient of 0.445. Now we need to know what angle of attack is needed for this lift coefficient. If we look at the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=b737c-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;midspan airfoil&lt;/a&gt; of the 737, this angle of attack is around 2.8 degree.&#xA;&lt;P&gt;&#xA;This source is for model airplanes, so their Mach and Reynolds numbers are much too low for the real thing, and we need corrections for both. Using the Prantdl-Glauert rule for Mach effects, we need to correct by dividing with $\sqrt{(1-Ma^2) \cdot (1 + tan\varphi)}$ = 0.693 at Mach 0.82. Please note that this increment must be applied to the zero-lift angle of attack, which is -1°. Now our angle of attack is only 1.63°. The flight Reynolds number of the 737's MAC is 22 million, so the angle of attack is even less, maybe 1.5°. Now we need a correction for the 737 wing sweep of 25 degree, which is computed by dividing the angle of attack by 0.9, the cosine of the quarter chord sweep angle. This gives about 1.8° as the corrected value.&#xA;&lt;P&gt;&#xA;So my quick-and-dirty answer is 1.8 degrees. Other sections of the wing have slightly different values, according to the wing's twist. Please note that the wing area of the 737 is roughly constant since the Sixties, while the mass has increased considerably. It is safe to assume that it is operating at higher angles of attack than the optimum for best range.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2017-03-23T18:26:05.977" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="5154" PostTypeId="1" AcceptedAnswerId="5158" CreationDate="2014-05-30T08:48:31.503" Score="6" ViewCount="2046" Body="&lt;p&gt;I have a question about flutter phenomena. As you know, flutter occurs when two modes (for example, first mode and second mode) coincide (that is, after a specific velocity, the frequencies of two modes will be the same and equal) and the damping term will change into positive which causes failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hrsAD.jpg&quot; alt=&quot;Figure 1&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for some cases, frequencies of two modes do not coincide perfectly (they are not equal) and damping parameter negative sign will change into positive, which mean flutter is happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HFJnW.jpg&quot; alt=&quot;Figure 2&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this happening? Why can't the frequencies of two modes coincide perfectly?&lt;/p&gt;&#xA;" OwnerUserId="2494" LastEditorUserId="72" LastEditDate="2014-05-30T09:55:30.940" LastActivityDate="2015-05-07T06:21:11.320" Title="Why can not two modes coincide perfectly for some cases in Flutter phenomena?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;flutter&gt;&lt;aeroelasticity&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5155" PostTypeId="1" AcceptedAnswerId="5194" CreationDate="2014-05-30T08:49:43.887" Score="10" ViewCount="2918" Body="&lt;p&gt;It seems that airline operational staff on the ground have the ability to initiate verbal communication with airline pilots on at least some airliners, in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously pilots can communicate with ATC using, for example, VHF radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps, even in aircraft where phone service is not available to passengers, pilots in the air and/or airline staff on the ground can&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;initiate a voice call using telephony equipment that is separate from any PSTN (public switched telephone network)?&#xA;&lt;ul&gt;&#xA;&lt;li&gt;using existing headset?&lt;/li&gt;&#xA;&lt;li&gt;using aircraft internal intercom handsets?&lt;/li&gt;&#xA;&lt;li&gt;some means of selecting the call recipient?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;send text messages over the data links (e.g. via ACARS (Aircraft Communications Addressing and Reporting System) through VHF (very high frequency) or SATCOM (satellite communication))?&lt;/li&gt;&#xA;&lt;li&gt;use private VHF frequencies to communicate with airline operations?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If any of this is true, how does this work from the perspective of a pilot, steward or an airline operational staff member on the ground?&lt;/p&gt;&#xA;" OwnerUserId="2493" LastEditorUserId="1696" LastEditDate="2014-06-02T16:10:03.970" LastActivityDate="2014-06-02T23:34:15.077" Title="What means do airline ground staff have to converse with pilots in flight?" Tags="&lt;radio-communications&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5156" PostTypeId="2" ParentId="5152" CreationDate="2014-05-30T15:55:04.360" Score="21" Body="&lt;p&gt;They aren't &quot;almost uniformly sheepskin&quot;, but they &lt;em&gt;are&lt;/em&gt; absolutely uniformly flame-resistant (or self-extinguishing) as required for aircraft certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sheepskin (and other natural wool fabrics) are both flame resistant and self-extinguishing (which is why &lt;a href=&quot;http://www.firesafetysource.com/site/948848/page/915479&quot;&gt;industrial fire blankets&lt;/a&gt; are often made of wool), and sheepskin tends to wear well, so it's a good choice for the two seats that will absolutely always be occupied when an aircraft is being operated.&lt;br&gt;&#xA;In terms of comfort, sheepskin covers also breathe well (so the pilots aren't sweating profusely while operating the aircraft - one of the reasons they're popular accessories for cars).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other popular fabric choices are natural leather, flame-resistant synthetic leather (vinyl), and various other textiles which pass the FAA &quot;burn test&quot; requirements (test procedures are described in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=28a04e1a8f29a43558dc9720849df91d&amp;amp;node=14:1.0.1.3.10&amp;amp;rgn=div5#14:1.0.1.3.10.7.107.32.10&quot;&gt;Part 23 Appendix F&lt;/a&gt; for light aircraft, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=28a04e1a8f29a43558dc9720849df91d&amp;amp;node=14:1.0.1.3.11&amp;amp;rgn=div5#14:1.0.1.3.11.9.201.2.22&quot;&gt;Part 25 appendix F&lt;/a&gt; for transport category aircraft).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-30T15:55:04.360" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5157" PostTypeId="2" ParentId="5071" CreationDate="2014-05-30T18:23:07.023" Score="14" Body="&lt;p&gt;The safest way to refuel an aircraft is with everything turned off and the airframe grounded (or bonded) to the fueling system.  This is often not practical (particularly for airliners), so a number of other rules exist to make refueling as safe as possible -- not using HF radio while refueling is one of them.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So why is the HF radio singled out? &lt;strong&gt;&lt;em&gt;Power&lt;/em&gt;&lt;/strong&gt;, combined with the antenna design factors you mentioned.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With small radios you can easily &lt;a href=&quot;https://www.youtube.com/watch?v=FSYj2lEaxhY&quot;&gt;light a fluorescent lightbulb&lt;/a&gt; (incidentally this is why radio geeks are such great fun at parties). HF radios can put out several hundred watts of power - this makes them more likely to generate a spark that can jump the gap between say a refueling nozzle and the refueling port/tank, igniting fuel vapors and ruining everyone's day.&lt;br&gt;&#xA;HF antenna designs which use the aircraft itself to radiate part of the energy can further increase the chance of a spark.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-05-30T18:23:07.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5158" PostTypeId="2" ParentId="5154" CreationDate="2014-05-30T19:33:50.243" Score="5" Body="&lt;p&gt;Flutter happens when the frequency of two modes coincide. These modes must be of different nature, so their frequencies can move in different directions. Typical examples are elastic modes (with eigenfrequencies independent of speed) and aerodynamic modes (with eigenfrequencies proportional to speed). When flight speed increases, the aerodynamic mode becomes faster (think of dynamic pressure as of the stiffness of the spring in a spring-mass system) while the elastic mode stays constant. At some point both have the same frequency, but flutter will already appear when they are close enough so each builds up the amplitude of the other. This will become more efficient when the frequencies are identical, but this is academic:  When flutter starts, it is a bad idea to accelerate further.&#xA;&lt;P&gt;&#xA;Example for an elastic mode: Wing bending. The first mode is just the tips moving up and down, the second mode is one tip up, the other down, which will rotate the fuselage, the third mode (or for pedants: The second symmetric mode) is again both tips up, but now with the midspan section moving down and so on. They are harmonics (like the oscillations of guitar strings), so their frequencies are at a fixed ratio, with the first mode having the lowest frequency. See below, from top to bottom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2KlMu.png&quot; alt=&quot;Stick-type drawings of different flutter modes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example for an aerodynamic mode: Aileron flutter, fast-period mode (especially when coupling to the bending mode in sweptback flying wings).&#xA;&lt;P&gt;&#xA;For me, your diagrams don't make sense. They should look more like that:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lSAgc.png&quot; alt=&quot;Frequency over speed for two phenomena&quot;&gt;&#xA;&lt;P&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;&lt;P&gt;&#xA;With Shellp's comments I realized that the answer above is too simple. The lines in the graph are for the static case of the elastic vibration. Once this wing moves through the air, it's movement will change the local aerodynamic forces, which will modify the flutter modes. The motion-induced aerodynamic forces counteract the elastic motion at slow speeds, adding damping (negative, because they reduce the motion). With damping, the frequency of the mode is reduced.&#xA;&lt;P&gt;&#xA;At higher speeds, delays in the buildup of pressures mean that now the aerodynamic forces lag behind the motion, and once this lag exceeds a quarter of a period, they produce positive damping (this is an unfortunate wording, so stay with me. The damping term is a negative number when it really damps the motion, but when the term becomes positive at higher speeds, it is still called damping, but now the motion is excited instead of damped in the common sense. So let's call positive damping &quot;excitation&quot; from now on).&lt;P&gt;&#xA;This excitation now increases the flutter frequency, so in reality the two flutter phenomena now get locked together. The first graph in the question above shows the frequency going down with speed, which looks unusual to me. The second graph shows this locking-in with an increase in frequency over speed, but at very high frequencies (it must be a small structure). If you want, the excitation is pushing the elastic frequency up, so both lock together without converging completely. But that cannot last forever - at higher speeds they should diverge, but in reality the structure is overloaded way before that happens.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:21:11.320" LastActivityDate="2015-05-07T06:21:11.320" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5159" PostTypeId="1" AcceptedAnswerId="5161" CreationDate="2014-05-30T21:03:44.363" Score="14" ViewCount="14621" Body="&lt;p&gt;I went for a 1.5 hour flight in a 1977 Cessna 172N, with several takeoffs and landings. I was alone. When I left, I had 18 gallons in each tank. When I arrived back, I had 15 gallons in the left tank, and 10 in the right tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was there such a disparity? Is this at all dangerous? Why did the right tank have less?&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="65" LastEditDate="2015-02-26T18:37:39.730" LastActivityDate="2017-05-31T20:40:13.433" Title="What could cause uneven fuel levels in a Cessna 172?" Tags="&lt;fuel-tanks&gt;&lt;cessna-172&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5160" PostTypeId="1" AcceptedAnswerId="5162" CreationDate="2014-05-28T18:51:13.393" Score="15" ViewCount="3842" Body="&lt;p&gt;Most modern commercial aircraft (e.g. 737, 767, 777, 787, 747-8, A380, etc.) feature inboard &lt;a href=&quot;http://www.google.com/search?as_q=&amp;amp;as_epq=nacelle+chines&quot;&gt;nacelle chines&lt;/a&gt; to improve flow over the upper surface of the wing at high angles of attack. However, many other similarly purposed aircraft (e.g. DC-8, L-1011, 757, 747-400) do not have nacelle chines. If these chines are so critical for optimum takeoff and landing performance, how are so many planes able to function just fine without them?&lt;/p&gt;&#xA;" OwnerUserId="2473" OwnerDisplayName="Bryson S." LastActivityDate="2014-05-30T22:23:58.443" Title="Why don't all aircraft use/need nacelle chines?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5161" PostTypeId="2" ParentId="5159" CreationDate="2014-05-30T21:49:38.093" Score="25" Body="&lt;p&gt;Consulting your handy POH (or one for a 172N that I Googled up) you'll find the fuel system diagram looks like the one below (click to enlarge - most high-wing gravity-fed fuel systems are similar).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sZOXT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sZOXTm.png&quot; alt=&quot;Cessna 172N Fuel System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there are a number of ways you could wind up with uneven fuel burn with this plumbing.&lt;br&gt;&#xA;The most common ones are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;(Uncoordinated) Turns&lt;/strong&gt;&lt;br&gt;&#xA;If you're flying lots of left-hand traffic patterns (or you're making lots of left turns for some other reason) that means your left wing is frequently lower, and gravity favors pulling fuel from the right tank. (Note that it doesn't have to be a turn - prolonged slips can also cause uneven fuel flow.)&lt;br&gt;&#xA;&lt;em&gt;If I had to take a guess, I'd say this is probably your culprit. Were you making a lot of left turns?&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Pressure&lt;/strong&gt;&lt;br&gt;&#xA;The fuel vent tube on the left tank faces into the wind - this pressurizes the left tank first (and the right tank through the breather tube connecting the two) - it's a little extra encouragement for fuel to leave the tanks and flow into the engine. In some aircraft this leads to the left tank draining faster (because it's at a slightly higher air pressure than the right tank) - this can become particularly pronounced if the breather tube between the two tanks is blocked.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0Z9E0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0Z9E0m.jpg&quot; alt=&quot;Cessna fuel vent&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Various blockages&lt;/strong&gt;&lt;br&gt;&#xA;A partial blockage in either of the tank fuel lines, the fuel selector valve, the vent, or the breather line between the two tanks could theoretically cause uneven fuel burn (the vent/breather blockages being a special case of &quot;pressure&quot; from (2) above).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Pilot Error&lt;/strong&gt;&lt;br&gt;&#xA;It's possible to mis-position the fuel selector in such a way that you're getting adequate fuel flow to run the engine, but one tank is more restricted than the other.&lt;br&gt;&#xA;This is unlikely if the aircraft is properly maintained (the fuel selector should have nice, identifiable detents that it clicks into, letting you know it's in position).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For more detail on causes for uneven fuel burn (and tips for troubleshooting it with your mechanic) check out &lt;a href=&quot;http://www.smokeeagles.com/sites/default/files/Uneven%20fuel%20flow.pdf&quot; rel=&quot;noreferrer&quot;&gt;Cessna Pilot's Association Technote 003&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Is uneven fuel burn dangerous? Maybe.&lt;br&gt;&#xA;It's certainly something you should be aware of (part of why you want your fuel gauges to be at least &lt;em&gt;somewhat&lt;/em&gt; accurate is so you can tell if your fuel burn is uneven in flight and correct it by switching to the fuller tank briefly).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Uneven fuel burn can be an annoyance (a 5 gallon difference is about 30lbs - potentially enough to notice on the controls), but it can also be a safety hazard: If allowed to go uncorrected you could theoretically get yourself into a situation where the right fuel tank is empty, and in a steep enough left turn you may not have enough pressure from gravity to get fuel from the left tank into the engine.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an extreme case your right tank may be empty and your left tank may be so low as to unport the fuel pickup tube in a turn, potentially leading to attitude-induced fuel starvation (&quot;The noisy part of the plane gets quiet until you level the wings&quot;). &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-05-31T18:26:50.590" LastActivityDate="2014-05-31T18:26:50.590" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="5162" PostTypeId="2" ParentId="5160" CreationDate="2014-05-30T21:58:19.390" Score="18" Body="&lt;p&gt;The chines help when the nacelle is very close to the wing. When the engine of Boeing's 737 was changed from the slim JT-8D to the higher bypass ratio CFM-56 on the 737-300 and later, the chines were essential to avoid large flow separation. Generally, aircraft with higher landing gear can afford to have more space between nacelle and wing and do not need fixes like chines. But when a new engine has been fitted to an existing design, chances are that some vortex generators are needed to fix the new flow conditions.&#xA;&lt;P&gt;&#xA;For the nitpickers: The 737-100 and 200 had underslung nacelles which left no space between wing and nacelle, but that is aerodynamically similar to a nacelle at a larger distance, because no narrow flow paths are created which produce steep pressure gradients. Only a closely mounted, but still separate nacelle will have these flow conditions which need to be remedied by energizing the boundary layer.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-05-30T22:23:58.443" LastActivityDate="2014-05-30T22:23:58.443" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="5163" PostTypeId="1" AcceptedAnswerId="5164" CreationDate="2014-05-31T15:05:23.273" Score="13" ViewCount="1605" Body="&lt;p&gt;Is it common, uncommon or rare for a non-towered airport to have ILS (Instrument Landing System) runways? Can a non-towered airport have ILS?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-01-06T15:34:24.700" LastActivityDate="2015-01-06T16:07:20.747" Title="Do non-towered airports commonly have ILS?" Tags="&lt;instrument-flight-rules&gt;&lt;approach&gt;&lt;ils&gt;&lt;non-towered-airport&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5164" PostTypeId="2" ParentId="5163" CreationDate="2014-05-31T15:24:33.230" Score="12" Body="&lt;p&gt;Nontowered airports absolutely can have ILS approaches, and it's fairly common, though of course not as common as at towered fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two examples in my neck of the woods are &lt;a href=&quot;http://www.airnav.com/airport/KIKK&quot; rel=&quot;noreferrer&quot;&gt;KIKK (Kankakee, IL)&lt;/a&gt; and &lt;a href=&quot;http://www.airnav.com/airport/KMTO&quot; rel=&quot;noreferrer&quot;&gt;KMTO (Mattoon, IL)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, at many towered airports, the tower is not 24/7 and closes at night. If such an airport has an ILS, it's still available after the tower closes; ATC services for IFR approaches are provided by a nearby/higher facility like a TRACON or ARTCC, just like a nontowered field. Two examples of &lt;em&gt;this&lt;/em&gt; in my neck of the woods are &lt;a href=&quot;http://www.airnav.com/airport/KCMI&quot; rel=&quot;noreferrer&quot;&gt;KCMI (Champaign, IL)&lt;/a&gt; and &lt;a href=&quot;http://www.airnav.com/airport/KBMI&quot; rel=&quot;noreferrer&quot;&gt;KBMI (Bloomington, IL)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not, however, aware of any Cat II or III ILS approaches at nontowered fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Protecting ILS Critical Areas is usually the responsibility of the tower, but even VFR aircraft are prohibited from entering the ILS Critical Area when the tower is closed:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Localizer Critical Area. Except for aircraft that land, exit a&#xA;  runway, depart, or execute a missed approach, vehicles and aircraft&#xA;  are not authorized in or over the critical area when an arriving&#xA;  aircraft is inside the outer marker (OM) or the fix used in lieu of&#xA;  the OM. &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html#aim0101.html.7&quot; rel=&quot;noreferrer&quot;&gt;AIM 1-1-9(k)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="909" LastEditorUserId="3504" LastEditDate="2015-01-06T16:07:20.747" LastActivityDate="2015-01-06T16:07:20.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5165" PostTypeId="2" ParentId="3838" CreationDate="2014-05-31T19:20:36.700" Score="4" Body="&lt;p&gt;Under the US FARs (at least part 91) nothing special is &lt;em&gt;required&lt;/em&gt; to take off in CAT IIIb weather besides an operational (and IFR-legal) aircraft and pilot. As mentioned elsewhere you can legally make that Zero/Zero takeoff where you can't even see the runway under your nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should go without saying that doing so would be incredibly stupid &lt;a href=&quot;https://aviation.stackexchange.com/questions/1195/when-do-i-need-a-takeoff-alternate?rq=1&quot;&gt;(we (and the FAA) have said so anyway)&lt;/a&gt;, but from a technical standpoint there's nothing preventing the operation except the knowledge that you might run off the side of the runway into a ditch and bang up your aircraft and passengers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In terms of what would be required to make the takeoff &lt;em&gt;safely&lt;/em&gt;, without running off the side of the runway into a ditch, I'd posit that you would need the same capabilities as you'd need to make the CAT IIIb &lt;em&gt;landing&lt;/em&gt; safely: Aircraft systems that let you reliably track down the centerline for takeoff (using the ILS or something of equivalent accuracy for guidance, and runway centerline lights).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would also need a reliable way to get from the gate to the runway, so taxiway centerline lights &amp;amp; stop bar lights are a must, and probably &lt;a href=&quot;http://en.wikipedia.org/wiki/ASDE-X&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASDE-X&lt;/a&gt; or its functional equivalent with a controller monitoring it to help ensure you don't taxi into another aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the above is predicated on, among other things, being able to see the lights I mentioned. The &lt;a href=&quot;http://www.rockwellcollins.com/sitecore/content/Data/Products/Displays/Head-Up_Displays-HUD/Head-up_Guidance_System.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;takeoff guidance system&quot;&lt;/a&gt; mentioned elsewhere adds synthetic vision into the mix which further enhances safety (and in the airline world allows takeoffs down to 300ft RVR). From what I can glean from the Rockwell-Collins marketing material their HGS seems to be able to provide &quot;follow the green dots&quot; taxi guidance (and presumably runway centerline guidance for the takeoff roll as well), providing redundancy for the lights I described above to help the pilot ensure the aircraft is going where they want it to.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-12-30T05:02:01.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5166" PostTypeId="2" ParentId="203" CreationDate="2014-05-31T21:42:19.897" Score="15" Body="&lt;p&gt;Floatplane operators may occasionally choose to takeoff with a light tailwind when to do otherwise would mean bucking a strong river current. I live on Oregon's McKenzie River, and doing this when operating out of Leaburg Lake (actually just a wide spot in the river) many years ago in a J3 on floats with only 85 horsepower made such takeoffs easier.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-06-01T03:44:25.253" LastActivityDate="2014-06-01T03:44:25.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5167" PostTypeId="1" AcceptedAnswerId="5169" CreationDate="2014-06-01T01:07:13.687" Score="20" ViewCount="5708" Body="&lt;p&gt;A common procedure in flight training is the low approach: simulating a landing, but without actually making contact with the ground before powering up and either going around in the traffic pattern or executing a missed approach procedure, sometimes after flying all the way down to an approach's minimums.&lt;/p&gt;&#xA;&lt;p&gt;In this situation, a pilot flies very close to the ground - one suggested crosswind training procedure suggests flying along the runway low enough that &amp;quot;&lt;a href=&quot;http://flighttraining.aopa.org/magazine/2004/October/200410_Features_Wing_low,_opposite_rudder.html&quot; rel=&quot;noreferrer&quot;&gt;[i]t's OK if the wheels inadvertently touch down during the exercise.&lt;/a&gt;&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Contrast this to other operations, including a simulated engine-out procedure away from an airfield. These are governed by &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/b4a0cab3e513bb58852566c70067018f/91693c93525de33e862576c100763e31!OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 91.119&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:&lt;/p&gt;&#xA;&lt;p&gt;(a) &lt;em&gt;Anywhere.&lt;/em&gt; An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.&lt;/p&gt;&#xA;&lt;p&gt;(b) &lt;em&gt;Over congested areas.&lt;/em&gt; Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of 1,000 feet above the highest obstacle within a horizontal radius of 2,000 feet of the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;(c) &lt;em&gt;Over other than congested areas&lt;/em&gt;. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Training for missed approaches and going around are important for basic skills, and they are performed very frequently. However, the regulations make no exception for training. For a maneuver where a pilot descends below 500 feet AGL without intending to land, is there legal guidance that makes this OK near a runway, or is it an unwritten exception?&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-12-28T00:13:06.747" Title="What makes intentional low or missed approaches legal?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;approach&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5168" PostTypeId="2" ParentId="5159" CreationDate="2014-06-01T01:32:11.010" Score="0" Body="&lt;p&gt;This is a small discrepancy in a tank that is quite difficult to measure accurately: it's wide, short, 2 meters in the air, the filler hole is at one end and it's on a contraption that is rather sensitive to the angle of the pavement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have (nearly) ZERO burn from one tank, you have a reason to see your mechanic and probe the fuel lines for a blockage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weight difference will not affect your flight. If one tank is empty and the other nearly full you may bank slightly to that side, but Cessnas can easily handle 800 pounds hanging on the wing strut.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="2143" LastEditDate="2015-10-30T23:55:10.150" LastActivityDate="2015-10-30T23:55:10.150" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5169" PostTypeId="2" ParentId="5167" CreationDate="2014-06-01T04:55:00.637" Score="10" Body="&lt;p&gt;Well, I'm going with &quot;It's a written exception, but nobody thought to include it in 14 CFR 91.119 though&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I say this because there are a number of regulations that require a student pilot or applicant for a license to receive and log flight training for go-arounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1894d3e3fbb584e8724476f982541e56&amp;amp;node=14:2.0.1.1.2.3.1.4&amp;amp;rgn=div8&quot;&gt;14 CFR 61.87 - Solo requirements for student pilots&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1894d3e3fbb584e8724476f982541e56&amp;amp;node=14:2.0.1.1.2.4.1.3&amp;amp;rgn=div8&quot;&gt;14 CFR 61.98 - Flight proficiency (Recreational Pilots)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1894d3e3fbb584e8724476f982541e56&amp;amp;node=14:2.0.1.1.2.5.1.4&amp;amp;rgn=div8&quot;&gt;14 CFR 61.107 - Flight proficiency (Private Pilots)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;And others&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The complete text of the private pilot SEL requirement (and they are all similar) is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§61.107   Flight proficiency.   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) General. A person who applies for a&#xA;  private pilot certificate &lt;strong&gt;must receive and log ground and flight&#xA;  training from an authorized instructor on the areas of operation&lt;/strong&gt; of&#xA;  this section that apply to the aircraft category and class rating&#xA;  sought.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) &lt;strong&gt;Areas of operation.&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) For an airplane category rating with a single-engine class rating:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Preflight preparation;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Preflight procedures;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Airport and seaplane base operations;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(iv) Takeoffs, landings, and go-arounds;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(v) Performance maneuvers;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vi) Ground reference maneuvers;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vii) Navigation;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(viii) Slow flight and stalls;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ix) Basic instrument maneuvers;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(x) Emergency operations;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xi) Night operations, except as provided in §61.110 of this part; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(xii) Postflight procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-06-01T04:55:00.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5170" PostTypeId="1" AcceptedAnswerId="5172" CreationDate="2014-06-01T12:24:15.380" Score="39" ViewCount="34787" Body="&lt;p&gt;Usually, there are four lights at the sides of runways which show airplanes' altitude status:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;four red lights: too low&lt;/li&gt;&#xA;&lt;li&gt;two red, two white: appropriate altitude&lt;/li&gt;&#xA;&lt;li&gt;four white lights: too high.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If two airplanes with two different altitudes approach, do they see different number of white and red lights? Or are the lights set for the closer airplane?   &lt;/p&gt;&#xA;" OwnerUserId="2281" LastEditorUserId="330" LastEditDate="2014-06-01T19:14:18.037" LastActivityDate="2021-03-18T06:03:20.430" Title="How do PAPI lights work?" Tags="&lt;runways&gt;&lt;papi&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5171" PostTypeId="2" ParentId="5170" CreationDate="2014-06-01T12:29:31.687" Score="9" Body="&lt;p&gt;The PAPI lights are not set for any airplane, they're unintelligent displays that are visible in different ways based on the angle of the viewer. For that reason, there can be an unlimited number of aircraft in view, and each will see the appropriate color selection.&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-06-01T12:29:31.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5172" PostTypeId="2" ParentId="5170" CreationDate="2014-06-01T12:33:34.483" Score="62" Body="&lt;h2&gt;Here's how the PAPI lights work:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Depending on the angle of the viewer, a different color is seen:&lt;/strong&gt;&#xA;&lt;img src=&quot;https://www.tc.gc.ca/media/images/ca-opssvs/ac300-002-figure5b.jpg&quot; alt=&quot;angle&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Then each light is calibrated to an angle:&lt;/strong&gt;&#xA;&lt;img src=&quot;https://www.tc.gc.ca/media/images/ca-opssvs/ac300-002-figure1.jpg&quot; alt=&quot;lights&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The good thing about this is that it's dead simple technology where very few things can go wrong: The lights have to be on and calibrated for the correct angle. The downside is that its usefulness decreases with lower visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some new systems appear to have solar panels as an off grid (and alternative/backup) power source which is sensible. Many systems today also have LED lights.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;If two airplanes with two different altitudes approach, do they see different number of white and red lights? Or are the lights set for the closer airplane?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;system is independent and passive&lt;/strong&gt;, in the sense that it never makes contact or note of the aircraft approaching. It lights up all to all aircraft in the beam. Hence, it 'works' for all aircraft at the same time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some new systems feature &lt;a href=&quot;http://rwsl.ll.mit.edu/DFW/FAROS.html&quot; rel=&quot;noreferrer&quot;&gt;FAROS&lt;/a&gt; (&lt;em&gt;Final Approach Runway Occupancy Signal&lt;/em&gt;) giving an indication that the runway may be occupied by another aircraft by flashing the lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;For a little information on differences between similar systems to PAPI, see &lt;a href=&quot;http://www.bayareapilot.com/vasiPAPI.htm&quot; rel=&quot;noreferrer&quot;&gt;this link&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.077" LastActivityDate="2015-01-04T23:35:00.490" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5173" PostTypeId="2" ParentId="5170" CreationDate="2014-06-01T12:33:43.630" Score="48" Body="&lt;p&gt;They use a lens system that projects the light in a narrow beam so each plane sees something different and makes the glide slope indicators a passive system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;you can see this nicely on a foggy morning:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dewitec.de/en/news/airfield-lighting/new-papi-bremerhaven-airfield&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ksxNh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-06-02T10:54:44.870" LastActivityDate="2014-06-02T10:54:44.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5174" PostTypeId="2" ParentId="5170" CreationDate="2014-06-01T12:37:37.217" Score="21" Body="&lt;p&gt;The lights you refer to are called PAPIs (Precision approach path indicators). They to do not change colour based on the altitude of the plane but are rather passive light boxes that have a different colour depending on the angle that you look at them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zAfAQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each light is mounted at a slightly different angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mjVbQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are at the neutral axis of such a light you will see a blend of red and white. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rne8V.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-06-01T12:37:37.217" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5175" PostTypeId="2" ParentId="5167" CreationDate="2014-06-01T14:19:11.243" Score="2" Body="&lt;p&gt;There aren't any rules that explicitly allow it, but you are practicing landing, so you can do what's necessary for landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, a common misconception with the minimum altitudes rule is that 500 feet AGL is the lowest you can go over uncongested areas.  That is not so, you can be 1 foot off the ground as long as you can still safely land if your engine dies and are still 500 feet away from structures, etc.  Most airports are in uncongested areas and don't have anything within 500 feet of the runway.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-06-01T14:19:11.243" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5176" PostTypeId="1" CreationDate="2014-06-01T15:43:05.570" Score="5" ViewCount="919" Body="&lt;p&gt;I would like to know where along the span of the 737 (let's say the NG) wing the two midsection airfoils are used. I am planning on running a CFD analysis of the 737 wing, and I need accurate data.&lt;/p&gt;&#xA;" OwnerUserId="2456" LastEditorUserId="1696" LastEditDate="2016-07-06T21:37:47.740" LastActivityDate="2016-07-06T21:39:41.333" Title="What are the locations on the Boeing 737 wing where the airfoil changes?" Tags="&lt;boeing-737&gt;&lt;airfoil&gt;" AnswerCount="0" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5177" PostTypeId="1" CreationDate="2014-06-01T15:52:54.027" Score="3" ViewCount="1480" Body="&lt;p&gt;I would like to know what airfoils are used for the Boeing 737 winglets.&lt;/p&gt;&#xA;" OwnerUserId="2456" LastEditorUserId="572" LastEditDate="2015-02-25T08:28:23.553" LastActivityDate="2015-02-25T08:28:23.553" Title="What winglet airfoils are used on the Boeing B737?" Tags="&lt;boeing-737&gt;&lt;winglets&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5178" PostTypeId="1" AcceptedAnswerId="5179" CreationDate="2014-06-01T16:37:02.847" Score="11" ViewCount="3138" Body="&lt;p&gt;If the crew never leave the plane, have they really entered the foreign country? What about if the crew leaves the plane, but not the airport? How do crews of international flights keep up with all of the visas they may need?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="6" LastEditDate="2014-06-02T18:12:27.823" LastActivityDate="2014-06-02T18:12:27.823" Title="Do crew need visas when landing at airports in countries other than their own?" Tags="&lt;airline-operations&gt;&lt;international&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5179" PostTypeId="2" ParentId="5178" CreationDate="2014-06-01T18:38:18.007" Score="10" Body="&lt;p&gt;It all depends on the laws of the country that the crew is visiting.  Some do and some don't.  Many do unless they have a reciprocal agreement with the pilot's country, in which case they don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be a great question for a specific country pair, or even if you want to know the laws about a specific country (in which case we could give the actual requirements), but the best answer for a general question like this is &quot;it depends&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, the crew isn't even required to clear customs unless they are leaving airport property.  Other times they have to clear as soon as they land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of qualifying for a route with the airlines is making sure that you have the required visas.  Having two passports help a &lt;strong&gt;lot&lt;/strong&gt; in getting multiple visas, because they can keep flying internationally while the visa application is in process.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-06-01T18:38:18.007" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5180" PostTypeId="1" CreationDate="2014-06-01T19:46:17.443" Score="4" ViewCount="1576" Body="&lt;p&gt;I know nothing about a Boeing 777 flight controls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, &#xA;I know that the speed of an aircraft is controlled by the throttle on the center console. I have never heard of an automatic speed control. I believe the pilot manually adjusts the speed.&#xA;I have heard of altitude hold control. You set it and the system keeps the aircraft at the same altitude. Is this independent of the auto-pilot?&#xA;And of course there's the auto-pilot. It makes the aircraft go in a direction you want it to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot does not intervene, what would happen if the auto-pilot and the altitude hold failed at the same time?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the aircraft climb or dive?  Dose it oscillate up and down?&lt;/li&gt;&#xA;&lt;li&gt;Does the aircraft roll over?&lt;/li&gt;&#xA;&lt;li&gt;Does the aircraft turn?&lt;/li&gt;&#xA;&lt;li&gt;What about speed?&lt;/li&gt;&#xA;&lt;li&gt;If it continues in some fashion, what is the effect of the fuel consumption in the different tanks? Is it automatically controlled? What happens if that control fails?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2498" LastEditorDisplayName="user2168" LastEditDate="2014-06-02T01:59:27.750" LastActivityDate="2018-06-28T23:26:12.990" Title="In a 777, what would happen if the auto-pilot and the altitude hold failed at the same time?" Tags="&lt;aircraft-performance&gt;&lt;boeing-777&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5181" PostTypeId="2" ParentId="5178" CreationDate="2014-06-01T19:52:19.380" Score="7" Body="&lt;p&gt;Addressing the &quot;If the crew never leave the plane, have they really entered the foreign country?&quot; question only -- yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've done numerous turns to Canada, Mexico and the Bahamas where we just drop off passengers, pick up the next load and fly back to the US (specifically IAH or EWR in my case).  When you get back to the US, you will go through customs &lt;em&gt;unless&lt;/em&gt; the station you did the turn at is a pre-clearance station (e.g. passengers go through US customs &lt;em&gt;before&lt;/em&gt; boarding).  There are no pre-clearance stations in Mexico that I know of, but Canada has many and there are also a few in Europe.   My experience is all in scheduled part-121 operations, and this may vary for other operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get off the plane during the turn (aside from pre-flight duties) then you get to go through the local customs, immigration and security screening to get back on your plane.  This was quite painful in airports like Montreal where the walk to customs and back to the plane can be quite long.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-06-01T19:52:19.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5182" PostTypeId="1" CreationDate="2014-06-02T01:39:16.673" Score="21" ViewCount="9369" Body="&lt;p&gt;I am tracking my kid's flight from LAX to EWR. It seems like a pretty straight West to East kind of flight but the flight path has the plane moving somewhat north through Ohio and then angling back to the south&lt;img src=&quot;https://i.stack.imgur.com/XuEA7.jpg&quot; alt=&quot;Flight path&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why wouldn't the flight just keep going East?&lt;/p&gt;&#xA;" OwnerUserId="2512" LastActivityDate="2014-06-03T17:05:07.860" Title="Why is the flight going north just to go south?" Tags="&lt;air-traffic-control&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5183" PostTypeId="2" ParentId="5182" CreationDate="2014-06-02T02:29:51.317" Score="3" Body="&lt;p&gt;Actually, that flight was first routed South of its original flight path, in order to avoid a very large storm system in the mid-west. At that point, it still could not head straight to Newark, due to another storm system in Indiana.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They were originally flying a little more East, but then got routed a 'smidge' North, to avoid the system, most likely when the system didn't move as fast as they figured. As to why they kept heading North-East, instead of a more direct path from Indiana, I cannot tell.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you (quickly) look at the flight on &lt;a href=&quot;http://flightaware.com/live/flight/VRD166&quot; rel=&quot;nofollow&quot;&gt;FlightAware.com&lt;/a&gt;, you can see the course corrections due to weather.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;scratch the following, the TFR (temporary flight restriction) isn't until later this week.&lt;/strong&gt;&lt;br&gt;&#xA;Another factor for this flight, was that it looks like once they went North to avoid the weather in Indiana, when they came east of the weather, if they'd have gone straight towards Newark at that time, there is a NOTAM for a TFR in Western Pennsylvania. So they most likely were shunted farther North by ATC in order to avoid the TFR.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorDisplayName="user2168" LastEditDate="2014-06-02T03:28:34.120" LastActivityDate="2014-06-02T03:28:34.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5184" PostTypeId="2" ParentId="5182" CreationDate="2014-06-02T03:39:48.043" Score="23" Body="&lt;p&gt;Aside from the storms causing an earlier re-routing, that jog north is to join the arrival into EWR.  A common fix in NE Ohio on flight plans into EWR is the DJB VOR which is in Loarine county (I think, somewhat near Cleveland). and then routing over Slate Run and then Williamsport, PA on the way into Newark.  If you are a jet coming from the west, this is literally the only way into EWR.  The other two ways in are from the south joining somewhere on a line between Atlanta and Baltimore (which you can transition to from the west by going over Beckley, WV) or from the north coming in over Albany, NY.  The primary reason for the strict routing starting at around the OH/PA border is the need for multiple arrival descents for both jets and turboprops into the various NY area airports (EWR, JFK, LGA, TEB, etc), the westbound departures out of NY center and the letters of agreement between Cleveland and NY centers to manage these traffic flows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this image:&#xA;&lt;a href=&quot;http://skyvector.com/?ll=41.35811968731203,-78.66870116557686&amp;amp;chart=301&amp;amp;zoom=8&amp;amp;plan=V.K5.DJB:F.K5.DORET:V.K6.SLT:V.K6.FQM:F.K6.SWEET&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VVYxP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This represents a route of ..J29.DORET.J584.SLT.FQM3.  This is not the exact route a LAX originating flight would normally get as they would end up a bit further north (going over Detroit instead of Cleveland), but they would still converge on J584.SLT.FQM3 (the portion east of the OH/PA border).  No matter your position west of the OH/PA border, Cleveland center is going find a way to put you on J584 before you get very far into PA.  This is why the flight couldn't just go direct to EWR and had to first fly north.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-06-03T17:05:07.860" LastActivityDate="2014-06-03T17:05:07.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5185" PostTypeId="1" AcceptedAnswerId="37405" CreationDate="2014-06-02T04:54:24.027" Score="4" ViewCount="47310" Body="&lt;p&gt;A flight leg is basically flight from one point to another point, (I'm not sure if flight leg number increase with touch and go around). I would like to know more about flight leg under what all conditions usually it increases and when it is reset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, most important why is it so important for an aircraft/airlines because usually it is 1 or 2 flight leg per travel. From what I know, flight leg is most important parameter in case of recording or storing data in NVM but I believe flight phase should be sufficient enough.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="504" LastEditDate="2014-06-02T15:47:05.693" LastActivityDate="2017-04-25T12:34:47.243" Title="What is a flight leg and why it is so important for an aircraft?" Tags="&lt;flight-controls&gt;&lt;flight-data-recorder&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5186" PostTypeId="2" ParentId="5180" CreationDate="2014-06-02T05:45:58.887" Score="1" Body="&lt;ul&gt;&#xA;&lt;li&gt;No, speed is not controlled by &quot;throttle&quot; on the center console&lt;sup&gt;1&lt;/sup&gt;. Due to the way aircraft longitudinal stability works, the elevators (controlled by control columns (yoke)) control speed and thrust or power&lt;sup&gt;2&lt;/sup&gt; levers control climb rate.&lt;/li&gt;&#xA;&lt;li&gt;Automatic speed control, &quot;autothrottle&quot; (A/T) is a cockpit automation mode that adjusts thrust to maintain speed. Since thrust does not control speed, it relies on someone operating the elevators to maintain flight path or at least attitude. This would normally be autopilot&lt;sup&gt;3&lt;/sup&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Altitude hold is one of the modes of &quot;autopilot&quot; (A/P). Autopilot controls both pitch and roll. Via pitch it can control vertical speed or altitude and via roll it can control direction. The term autopilot may be used including or excluding A/T.&lt;/li&gt;&#xA;&lt;li&gt;At altitude it becomes increasingly difficult to fly by hand. To allow lower separation, aircraft are only allowed above FL290 if they are equipped with working altitude hold and pilots would normally use it.&lt;/li&gt;&#xA;&lt;li&gt;That does not mean the pilots are not watching the instruments. In case the autopilot fails, they would resume flying manually.&lt;/li&gt;&#xA;&lt;li&gt;If the pilots did not assume control, than the aircraft would start a &lt;a href=&quot;http://en.wikipedia.org/wiki/Phugoid&quot; rel=&quot;nofollow&quot;&gt;Phugoid oscillation&lt;/a&gt;. It would continue straight, but since the lateral stability is rather weak&lt;sup&gt;4&lt;/sup&gt; if turbulence caused it to bank to the side, it could overbank and enter &lt;a href=&quot;http://en.wikipedia.org/wiki/Graveyard_spiral&quot; rel=&quot;nofollow&quot;&gt;Graveyard spiral&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Normally engines only take fuel from their side&lt;sup&gt;5&lt;/sup&gt;. But both engines are normally consuming the fuel at the same rate and the initial amount is the same on both sides, so they would both run out quickly after each other.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;Except if you engage the autopilot vertical speed or altitude hod mode or in Airbus with it's normal law which automatically retrims the aircraft for current speed to maintain flight path which is similar automation but built into the system and never disengaged except in case of failure.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;sub&gt;&quot;Throttle&quot; refers to the flap restricting airflow to the engine, which is specific to spark-ignition reciprocating engines. Compression-ignition (diesel) engines and turbines are controlled by directly adjusting the fuel flow, don't have throttle and thus the levers are not usually called &quot;throttle&quot; in them. They are called &quot;power&quot; levers for propeller engines (turboprop and diesel) and &quot;thrust&quot; levers for jet engines, reflecting the difference in the engine behaviour with increasing speed.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;&lt;sub&gt;While A/P and A/T can always be engaged independently, in most aircraft it is recommended to always used both or neither. Exception is again Airbus where A/T without A/P makes sense.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;4&lt;/sup&gt;&lt;sub&gt;Making the aircraft laterally stable is possible, but unfortunately it aggravates the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow&quot;&gt;Dutch roll&lt;/a&gt; mode. So usually the lateral stability is limited and will only return the aircraft to level from small disturbances.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;5&lt;/sup&gt;&lt;sub&gt;I am not sure whether on B777 the centre tank feeds the engines directly or transfers to the wing tanks, but the result is not much different.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-06-02T06:01:00.493" LastActivityDate="2014-06-02T06:01:00.493" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5187" PostTypeId="2" ParentId="5180" CreationDate="2014-06-02T06:33:57.250" Score="11" Body="&lt;p&gt;Regardless of whether it's a 777 or any other airplane where the altitude is being held by the autopilot and the altitude hold function stops, whether because of general autopilot failure, just altitude hold failure, or the altitude hold function is inadvertently or purposely switched off; the airplane will seek whatever pitch attitude it is trimmed for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, using the 747-100 and -200 autopilot setup, let's say you are in cruise at 35,000 ft, the autopilot is navigating and altitude hold is on. Further, let's say we're beyond 1990, and many operators of those aircraft had disabled autothrottles because they were a maintenance hog. Thus the airplane is maintaining whatever speed has resulted from where you have positioned the power levers. The altitude hold function is maintaining altitude by using the elevator. You can look down at an indicator on the center console between the pilots to see the degree of up or down elevator being used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the flight progresses and fuel is burned, the c.g. moves forward and the altitude hold function adds more up elevator to maintain altitude. When a certain amount of up elevator amount is reached, the system automatically retrims so that no up elevator force is required.  You hear and see it happen because the large trim wheel on the right side of the center console rotates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're a good captain or a good flight engineer, you can monitor the amount of up elevator force being held and trim it out manually before it reaches enough to trigger the automatic retrim, and save the company a little fuel money (or if you're JFK to Tel Aviv in a -100, possibly avoid a fuel stop in Athens).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's say that you reach up and disengage the altitude hold sometime between retrimmings. The airplane will nose down, and actually quite abruptly if it's been awhile since it last retrimmed. So abruptly that normal practice was to always have the yoke in hand before disengaging the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say that you that you let the condition persist. The nose is down, so the airplane would descend, of course. The speed would oscillate during the descent. If there was a severe nose down trim ... well, you wouldn't want to go there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a humorous account (at least meant to be humorous) of the altitude hold function being inadvertently disengaged, go to &lt;a href=&quot;http://terryliittschwager.com/hajj4contest.php&quot; rel=&quot;noreferrer&quot;&gt;http://terryliittschwager.com/hajj4contest.php&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the case of total autopilot failure, I defer to the other answer already here when I posted this. Suffice it to say that the pilots would have to take control in short order to avoid an extremely serious condition, very possibly the loss of the aircraft. You can go to &lt;a href=&quot;http://community.seattletimes.nwsource.com/archive/?date=19911219&amp;amp;slug=1323954&quot; rel=&quot;noreferrer&quot;&gt;http://community.seattletimes.nwsource.com/archive/?date=19911219&amp;amp;slug=1323954&lt;/a&gt; for information on an incident that involves such. The interesting thing is this airplane had started to do this a number of times (including once to me coming out of Hong Kong), but in previous instances the pilots quickly recognized that the autopilot had failed and had taken control before things got serious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following the incident described, the airplane was repaired and reentered service, and we called her Christine.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-06-02T06:53:57.590" LastActivityDate="2014-06-02T06:53:57.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5188" PostTypeId="2" ParentId="5182" CreationDate="2014-06-02T07:52:23.687" Score="13" Body="&lt;p&gt;Part of the answer is that, as noted in waiwai933's comment, the earth is (roughly) a sphere, not a flat plane. This means that the shortest distance between two points is not a straight line on the map but what's called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Great_circle&quot; rel=&quot;nofollow noreferrer&quot;&gt;great circle&lt;/a&gt;. To find this, you'd take a circle whose centre is the centre of the earth and which passes through the two points you're trying to connect. The shorter route along that circle is the great circle distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The intuitive reason for this is that the earth is &quot;narrower&quot; closer to the poles so you can gain a lot by flying towards the pole, using the &quot;narrowness&quot; and then flying away from the pole again. The &quot;ideal&quot; route from LAX to EWR is this (images from &lt;a href=&quot;http://www.gcmap.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;gcmap.com&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ESuL8.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A much more pronounced version of this would be if your son was flying to Casablanca instead of Newark.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/46dxl.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although Los Angeles and Casablanca are at roughly the same latitude, the shortest route between them actually goes over Canada, over a thousand miles to the north of LA!&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-06-02T07:52:23.687" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="5189" PostTypeId="2" ParentId="5185" CreationDate="2014-06-02T08:21:05.750" Score="10" Body="&lt;p&gt;I don't think flight leg is important for either aircraft no airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons why most flights have one or two legs is purely economic. Aircraft have to be operated with rather high load factor to be profitable. If you have a line with less passengers, you really want to use smaller plane or run it less often. Because different links have different demand, it's rather rare to have many consecutive links with similar demand so it would make sense to fly them with one plane as multi-leg flight. And few people would want to fly the whole trip as the stop-overs take rather long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft what matters is not legs, but &lt;em&gt;cycles&lt;/em&gt;, meaning &lt;em&gt;pressurization cycles&lt;/em&gt;. For pressurized aircraft the material fatigue is most closely related to the cycles and since each cycle also involves one period of running the engines at high thrust, the engine wear is also somewhat related. It does not matter whether the aircraft accumulates 4 cycles in 4-leg journey or 4 separate journeys.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-06-02T08:21:05.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5190" PostTypeId="2" ParentId="5185" CreationDate="2014-06-02T08:54:14.537" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;what is flight leg?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A flight leg is a trip of an aircraft, from take-off to landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use of the term implies a multi-leg flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the point of view of an aircraft's operator, it is a smaller part of an overall journey which involves landing at an intermediate airport. Each leg starts and ends at a different airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the point of view of a passenger it is a part of a journey that may start or end with a stopover, a change of plane or a change of airline.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;why is it important for an aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It isn't really. See &lt;a href=&quot;https://aviation.stackexchange.com/a/5189/1289&quot;&gt;Jan's answer&lt;/a&gt; regarding aircraft &lt;em&gt;cycles&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is obviously important administratively for scheduling and financially for optimizing return on investment etc.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-06-02T08:54:14.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5191" PostTypeId="1" AcceptedAnswerId="5192" CreationDate="2014-06-02T15:51:32.990" Score="10" ViewCount="23316" Body="&lt;p&gt;Is fixed wing more efficient than rotary wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, why is that?&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="19" LastEditDate="2016-06-22T07:58:37.957" LastActivityDate="2019-02-14T19:43:36.550" Title="How does the efficiency of a fixed wing compare to a rotary wing?" Tags="&lt;fuel&gt;&lt;fixed-wing&gt;&lt;rotary-wing&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5192" PostTypeId="2" ParentId="5191" CreationDate="2014-06-02T16:05:07.567" Score="12" Body="&lt;p&gt;Helicopters use more fuel than airplanes (considering everything else being equal).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When helicopters are traveling slow, they need more energy to hold their weight. When traveling fast (according to their standards), the rotor drag is very high. This is the primary reason they need more power. More Power = More Fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conventional aircraft have much less drag at a given weight and speed than a helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters travel slow. When they burn more fuel per hour and travel slowly, fuel consumption per mile is much worse. They also stay low. Most have turbine engines, turbines burn lots of fuel at low altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has a good article about &lt;a href=&quot;http://en.wikipedia.org/wiki/Energy_efficiency_in_transportation#Small_aircraft&quot; rel=&quot;noreferrer&quot;&gt;energy efficiency in different vehicles&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Two-seater and four-seater flying at 250 km/h with old generation engines can burn 25 to 40 liters per flight hour, 3 to 5 liters per&#xA;  100 passenger km.&lt;/li&gt;&#xA;  &lt;li&gt;The Sikorsky S-76C++ twin turbine helicopter gets about 1.65 mpg-US (143 L/100 km; 1.98 mpg-imp) at 140 knots (260 km/h; 160 mph) and&#xA;  carries 12 for about 19.8 passenger-miles per gallon (11.9 litres per&#xA;  100 passenger km).&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2017-09-20T20:26:40.673" LastActivityDate="2017-09-20T20:26:40.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5193" PostTypeId="2" ParentId="5191" CreationDate="2014-06-02T16:05:32.977" Score="9" Body="&lt;p&gt;Fixed wing aircraft are generally much more efficient than rotary aircraft. This is because of the difference in how they generate lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For fixed wing aircraft, they use an engine to keep the plane moving forward. The air flow over the wings generates lift. The engine must only overcome the drag of the airplane (in level flight). This drag is both due to the form drag of the plane and the generation of lift from the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a rotary aircraft, the engine keeps the rotors moving. The rotation of the rotors generates lift, but this is also the main force used to move the aircraft forward. So in this case, the rotors not only provide the lift to keep the aircraft in the air, but also the thrust to keep it moving forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a fixed wing aircraft, the propeller can be made to be efficient at providing forward thrust, and the wing can be made efficient at providing lift. In a rotary aircraft, the rotors must serve in both roles, and result in a compromise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a helicopter enters a hover, it is using all of its power to provide lift, while a fixed wing aircraft can enter a holding pattern with still only enough power to offset the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing the efficiency of lift versus drag of &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift-to-drag_ratio#Examples&quot;&gt;different aircraft&lt;/a&gt; shows the lower efficiency of a helicopter. A Cessna 150 has an L/D (lift to drag ratio) of 7 in cruise, while a helicopter would only have around 4.5 in cruise. Other sources show that small aircraft can achieve an L/D of &lt;a href=&quot;http://history.nasa.gov/SP-468/ch6-3.htm&quot;&gt;over 10&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a speed limit for helicopters that prevents them from going as fast as most turboprop or jet aircraft. This is because the tips of the rotors should stay at subsonic speeds. Current helicopters like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sikorsky_UH-60_Black_Hawk#Specifications_.28UH-60L.29&quot;&gt;UH-60&lt;/a&gt; are limited to around 200 knots. Newer designs such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurocopter_X3&quot;&gt;Eurocopter X3&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Sikorsky_X2&quot;&gt;Sikorsky X2&lt;/a&gt; are capable of up to 250 knots, but are still in development.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison, a small helicopter and small fixed wing plane. Even though the PA-31 (fixed wing) is heavier than the 206 (helicopter) and can carry more passengers, it can fly faster and further than the helicopter. The &quot;fuel economy&quot; of nautical miles per gallon is based on the fuel capacity and max range, so it's not an exact figure of actual fuel burn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the PA-31 ended production in 1984, while the 206B-L4 is the latest version still in production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_206#Specifications_.28206B-L4.29&quot;&gt;Bell 206B-L4&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1 pilot, 4 passengers&lt;/li&gt;&#xA;&lt;li&gt;Max speed 120 kts&lt;/li&gt;&#xA;&lt;li&gt;Range 374 nm&lt;/li&gt;&#xA;&lt;li&gt;Fuel 110.7 gal&#xA;&lt;ul&gt;&#xA;&lt;li&gt;3.4 nm/gal&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-31_Navajo#Specifications_.28PA-31_Navajo.29&quot;&gt;PA-31 Navajo&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;2 pilots, 7 passengers&lt;/li&gt;&#xA;&lt;li&gt;Max speed 227 kts&lt;/li&gt;&#xA;&lt;li&gt;Range 1011 nm&lt;/li&gt;&#xA;&lt;li&gt;Fuel 187 gal&#xA;&lt;ul&gt;&#xA;&lt;li&gt;5.4 nm/gal&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-02T19:47:35.320" LastActivityDate="2014-06-02T19:47:35.320" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5194" PostTypeId="2" ParentId="5155" CreationDate="2014-06-02T23:34:15.077" Score="9" Body="&lt;p&gt;There are numerous methods for air-to-ground communications.  I may be missing a few, but off the top of my head, here are the ones I can remember:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;normal VHF comms&lt;br&gt;&#xA;Operational staff at the airport maintain an operations frequency that you can use just as you would would ATC.  The limiting factor here is the requirement of line-of-sight with the ground antenna and this limits range.  We could normally raise ops about 30-40 minutes out, at altitude, if someone was actually listening.  This is similar to a GA pilot calling unicom to arrange ground services.  This method is also used for maintenance at some stations and for talking to fuelers and deicing operators.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/SELCAL&quot;&gt;SELCAL&lt;/a&gt;&lt;br&gt;&#xA;This is a selective calling protocol that operates over HF and VHF frequencies.  Each participating airplane and ground station (typically a dispatcher or ATC) has a code and if you know the code you want to communicate with, you can establish two-way communications with them.  To use this in the air required tuning a specific frequency and using a hand-mic with a keypad to dial the ground station code.  On the ground I'm not sure the exact method they use (phone patch?) but when they called us we'd get an aural &quot;SELCAL&quot; announced by the airplane along with a light to alert us.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.arinc.com/sectors/aviation/aircraft_operations/commercial_aviation/voice_data_comm/air_ground_data/radio_svc/international.html&quot;&gt;AIRINC phone patch&lt;/a&gt;&lt;br&gt;&#xA;This service provides VHF-to-PSTN patches and allows you to call your dispatchers actual phone, medlink, or anyone with a phone you feel like calling.  This worked by calling an operator over the normal radios and having them dial a number and connecting us together.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Satellite phone&lt;br&gt;&#xA;Works just like any other satellite phone and use the Iridium network.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot;&gt;ACARS&lt;/a&gt;&lt;br&gt;&#xA;This works just like text messaging.  Select your recipient, type a message and hit send.  You get alerts when messages arrive.  The interface I'm familiar with in the airplane is a program in the FMS with limited pre-set recipients you could contact (dispatch and perhaps a few others).  The ACARS software can also be setup to send specific messages to specific stations, e.g. an &quot;In-Range&quot; message which is routed to operations at your destination.  From the ground side, this is usually baked into the dispatch flight-following software.  Our dispatchers could right click on an airplane, get a menu, pick &quot;text message&quot; and type a message that would be sent to that airplane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-06-02T23:34:15.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5195" PostTypeId="1" AcceptedAnswerId="5196" CreationDate="2014-06-02T23:43:29.450" Score="10" ViewCount="5274" Body="&lt;p&gt;On August 9th, 2007 an Air Moorea Twin Otter &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Moorea_Flight_1121&quot;&gt;crashed into the ocean&lt;/a&gt;. The cause of the crash was determined to be loss of pitch control after an elevator cable snapped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my world (Cessna 152), if an elevator control broke I would be pretty sad, but the pitch trim tabs would probably allow me to put the plane down safely &lt;strong&gt;somewhere&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I could tell based on my research, the Twin Otter is equipped with a pitch trim tab (aircraft are required to have them, but they can come in a variety of forms). Why couldn't the pilot use pitch trim to descend safely?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;--EDIT--&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my checklists, I am required to &quot;set trim for takeoff&quot; in the engine run up. What is the point of this step if that trim setting doesn't hold the proper attitude for not falling out of the sky?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;--EDIT #2--&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a &lt;strong&gt;highly&lt;/strong&gt; hypothetical follow up question, would it have been possible, with 400' of altitude, for the pilot to go so hard nose down that he could pull out in an inverted configuration and fly the plane safely that way (the only cable that snapped was the elevator-down cable)?&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="938" LastEditDate="2014-06-03T20:05:21.950" LastActivityDate="2014-08-16T21:45:09.467" Title="Why couldn't Air Moorea Flight 1121 use pitch trim to land safely?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;trim&gt;&lt;elevator&gt;&lt;pitch&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5196" PostTypeId="2" ParentId="5195" CreationDate="2014-06-03T02:11:54.697" Score="19" Body="&lt;p&gt;All quotes in this answer are from the &lt;a href=&quot;http://www.bea.aero/docspa/2007/f-qi070809.en/pdf/f-qi070809.en.pdf&quot;&gt;English translation of the BEA accident report&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The elevator cable broke at &quot;an altitude estimated at between three and four hundred feet&quot;,(p. 7) and there were eleven seconds between that time and the point of impact. If it had happened higher, the pilot would potentially have had time to figure out what happened and pull out of the dive with trim. Taken by surprise and not knowing what happened, the pilot simply did not have time to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Twin Otter would have been demonstrated to be recoverable from an elevator cable break as part of its certification (p. 17):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The CAR 3 regulation, basis of certification for the DHC6, requires a flight test demonstrating the aeroplane’s capacity to land using only the elevator trim in the case of failure of the primary longitudinal control of the aeroplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, there's a big difference between &quot;can be landed using just trim&quot; and &quot;can be recovered by a pilot who is surprised by the emergency&quot;. Flight tests performed during the investigation showed (p. 63, emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At [the height the incident aircraft was at], &lt;strong&gt;only immediate action&lt;/strong&gt; on the trim located on the centre pedestal would make it possible to recover the airplane. The test also showed that from level flight it takes about three seconds for a pilot &lt;strong&gt;trained for&lt;/strong&gt; and &lt;strong&gt;prepared for this exercise&lt;/strong&gt; to recover the airplane. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, on this flight there simply was not enough time to discover the problem, figure out what went wrong, and recover (p. 63):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The highly dynamic nature of the events following the failure must be emphasized here. Eleven seconds passed between the pilot’s exclamation and the impact. This only left a short time for the pilot to analyse the situation and apply a solution that he had to improvise. In addition, the stress associated with the airplane’s attitude and the difficulty in estimating his height, in the conditions on the day, in relation to the surface of the water, certainly affected his powers of analysis. The pilot was not trained or prepared, either during his training or during type rating, as indeed most pilots aren’t, to react to a loss of pitch control. Only a reflex action could thus have&#xA;  allowed him to recover the airplane before the impact.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To answer the edits to the question, note that the airplane was not trimmed to &quot;fall out of the sky&quot;. The pilot called out the trim checklist item before flight(p. 17), and so should have set it to the takeoff setting. Presumably this would require gentle back-pressure for rotation and climb. The event that initiated the failure process was retracting the flaps(p. 39). This changed the flight dynamics, and therefore the elevator control loads. The flight testing discovered that this created a &quot;pitch-down moment&quot;(p. 39):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To counter this effect and maintain the aeroplane on its initial trajectory, it was necessary to exert considerable pitch-up effort on the elevator control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is not a cause for concern. The procedure is to hold pressure on the controls and adjust trim to relieve the pressure. However, it was at this point that the elevator cable snapped, so the pilot was interrupted and didn't complete the process. If the incident had happened at a higher altitude, the airplane would have recovered itself from the upset (p. 42):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[S]tick free, the flap retraction led to a pitch-down moment varying the aeroplane&#xA;  trim between 20° and 30°, the rate-of-climb indicator going to stop at less than&#xA;  3,000 ft/min and speed reaching 140 kt in twenty seconds, then the aeroplane&#xA;  recovered on its own in level flight in five seconds, the total loss in height being&#xA;  seven hundred feet[.]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To the last question, flying inverted would not be necessary for recovery. I do not know the maneuvering characteristics of the DH-6, but I am unsure that an outside loop could successfully be completed starting at 300-400 AGL.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2014-06-03T21:32:24.597" LastActivityDate="2014-06-03T21:32:24.597" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5197" PostTypeId="1" AcceptedAnswerId="5205" CreationDate="2014-06-03T07:26:07.397" Score="46" ViewCount="4844" Body="&lt;p&gt;If the Wright brothers were still alive (and in very good health for their age), could they fly one of their aircraft across the United States today?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, I'm looking at the &lt;a href=&quot;http://en.wikipedia.org/wiki/Wright_Model_B&quot;&gt;Wright Model B&lt;/a&gt;, a commercially-produced biplane with a maximum speed of 45 mph, a range of 110 miles, and no radio on board.  It was originally produced in 1910, while the first flight across the US (with plenty of stops) was in 1911.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could a pilot with a Wright Model B use modern airports?  Could they navigate?  Could they keep to their designated airspace?  Could they do all they needed to do to fly in an FAA-approved manner?&lt;/p&gt;&#xA;" OwnerUserId="2524" LastActivityDate="2014-06-05T04:56:58.407" Title="Could the Wright brothers fly across the US today?" Tags="&lt;aviation-history&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5198" PostTypeId="2" ParentId="5197" CreationDate="2014-06-03T11:44:53.793" Score="15" Body="&lt;p&gt;You can fly coast to coast without once speaking to ATC or landing in a towered field. Sure, around major cities there are areas where you need a transponder and/or a radio to legally enter but the majority of airspace in the US is still uncontrolled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, it would be much easier and less risky than in the old days given modern handheld gps  units and weather reporting. In the old days there was no weather information, pilots could easily find themselves flying into poor visibility. In the old days there were few reliable road maps, much less anything aviation related, nowdays handheld GPS units and printed charts make navigation simple. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These days you can hop from one airfield to another and know where you are going, how long it will take to get there, and what conditions you can expect along the way. There's also many places to refuel or get maintenance. Personally I think Orville and Wilbur would be pleased with what they would find. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1467" LastEditDate="2014-06-03T13:47:50.213" LastActivityDate="2014-06-03T13:47:50.213" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5199" PostTypeId="2" ParentId="5195" CreationDate="2014-06-03T13:18:10.397" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;In my checklists, I am required to &quot;set trim for takeoff&quot; in the engine run up. What is the point of this step if that trim setting doesn't hold the proper attitude for not falling out of the sky? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A major cause of accidents on take-off and landing is a stall followed by a spin. A wing stalls when it reaches the critical angle of attack, which is much easier to do at the lower speeds required on take-off and landing. If you set a nose-up trim you will need to use forward-pressure to keep the aircraft at a safe airspeed, if you then took your hands off the controls you could find yourself at stall speed in a matter of seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's better to require a bit of back-pressure to gain altitude, at least that way if you let go you will gain, rather than lose airspeed. Once you have an established climb speed and stable pitch attitude you can then trim for the climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example of how this can save your life. Imagine you are in your Cessna 152, 300 feet agl in a climb. Suddenly your seat rolls back all the way due to a broken seat lock (it's happened to me in a 152). It's much easier to put forward pressure on the controls in that situation than back pressure, and a bit of nose down trim would cancel out the sudden backward move of your C of G somewhat. Having nose up trim in that situation could potentially put you in a non-recoverable situation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So take-off trim is actually designed to keep you from falling out of the sky. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1467" LastEditDate="2014-06-03T13:49:18.190" LastActivityDate="2014-06-03T13:49:18.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5200" PostTypeId="1" AcceptedAnswerId="5203" CreationDate="2014-06-03T13:53:39.087" Score="23" ViewCount="5404" Body="&lt;p&gt;I'm taking a guess and assuming the &lt;a href=&quot;http://en.wikipedia.org/wiki/Wright_Flyer&quot;&gt;Wright Flyer&lt;/a&gt; was incapable of flying upside down.  I'm just guessing it probably lacked the power... ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what was the first plane that could fly inverted for a sustained period of time (10sec+) with full power?  I'm assuming you would need an engine that was okay being upside down*, and had the power to get you high enough to make the maneuver safe.  Then you'd need an airfoil that worked inverted (some of the high early cambered wings may have had problems, for example) and controls that functioned in that environment as well.  Probably a seat belt would be useful too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anybody know what plane was the first one to have all of these, and then went ahead and flew upside down?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus points: I also wouldn't mind knowing what plane was the first to simply fly inverted, even if for a brief moment...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*As Jan Hudec pointed out, the engine itself doesn't really care, but the fuel system might.  So really we should be asking when the first fuel system that could go upside down was produced...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-06-03T14:47:41.420" LastActivityDate="2015-05-07T06:22:49.113" Title="What was the first aircraft that could fly inverted?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;piston-engine&gt;&lt;wing&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5201" PostTypeId="2" ParentId="5200" CreationDate="2014-06-03T14:26:49.317" Score="27" Body="&lt;h1&gt;Deliberate momentarily inverted flight&lt;/h1&gt;&#xA;&lt;p&gt;The first reported deliberately inverted flight was probably in a Blériot model XI.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KFYTc.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Inverted flight was also being considered. Several pilots had inadvertently found themselves upside down as a result of wind gusts, but no one had yet attempted it intentionally. Adolphe Pegoud decided he would be the one to try.&lt;/p&gt;&#xA;&lt;p&gt;Pegoud was one of the first true aerobatic pilots. An accomplished test pilot with the Bleriot team, he was also the first flyer to jump from a plane with a parachute. Both Pegoud and the aircraft landed, unharmed. Having decided to try upside-down flying, Pegoud first practiced in a hanger [sic] in a plane hung upside down from the ceiling. He correctly assumed the controls would have to be operated in a reverse manner and he wanted to get the feel of it before actually flying.&lt;/p&gt;&#xA;&lt;p&gt;It must have worked. Shortly thereafter, Pegoud made the first public demonstration of inverted flight in September of 1913. During this flight, he was the first to perform a half roll to an inverted position--another aerobatic maneuver was born. The flight did point out one potential problem: While Pegoud was prepared to fly inverted, the aircraft was not. It proceeded to drench the flyer with fuel!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.flightsimbooks.com/jfs2/chapter1.php&quot; rel=&quot;noreferrer&quot;&gt;The history of aerobatics&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h1&gt;Deliberate sustained inverted flight&lt;/h1&gt;&#xA;&lt;p&gt;This would have to have been an aerobatic aircraft specially modified for inverted flight&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;flop tubes in the fuel tank?&lt;/li&gt;&#xA;&lt;li&gt;fuel-injection not carburettor?&lt;/li&gt;&#xA;&lt;li&gt;strengthened and/or braced to allow wings to support fuselage in inverted position?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h2&gt;1925&lt;/h2&gt;&#xA;&lt;p&gt;June 1925, No 32 Squadron did an air display demonstrating Flight-converging bombing at the R.A.F Display, Hendon. Scott was selected to do individual aerobatics in a brand-new Snipe which he was allowed to paint red, this pleased Scott greatly as it meant that he was also allowed to practice his aerobatics at a low altitude, rather than above 2000 feet which was R.A.F regulations at that time. In Scott's book he tells of how for his solo display he was allotted exactly seven minutes during the luncheon break, to complete his show but after just two minutes, a flying wire broke in the near edge of the port side, anxious not to cut his allotted seven minutes down too much &lt;strong&gt;he began to fly the aircraft upside down in an effort to reduce the strain on the flying wires, he continued flying in an inverted position for some time&lt;/strong&gt; until he noticed a worrying quiver in the top plane and promptly landed slightly short of his seven minutes.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/C._W._A._Scott&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h2&gt;1933 record&lt;/h2&gt;&#xA;&lt;p&gt;In 1933, &lt;a href=&quot;http://www.dmairfield.org/airplanes/NC872H/index.html&quot; rel=&quot;noreferrer&quot;&gt;NC872H&lt;/a&gt;, a Boeing 100, was flown inverted for 4 hours 5 minutes and 22 seconds.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Jnbwq.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;After its career with Pratt &amp;amp; Whitney, the Museum of Flight's aircraft was sold to Milo Burcham on September 27, 1933. He modified it for skywriting and air-show work, painted it blood red, added fuel and oil systems for inverted flight, and &lt;strong&gt;flew it upside down from Los Angeles to San Diego&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.museumofflight.org/aircraft/boeing-100p-12f4b&quot; rel=&quot;noreferrer&quot;&gt;Seattle Museum of Flight&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-09T14:56:56.547" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5202" PostTypeId="1" AcceptedAnswerId="5210" CreationDate="2014-06-03T15:06:18.430" Score="9" ViewCount="2878" Body="&lt;p&gt;I would like to know about any rules that would authorize a pilot to refuse to allow a specific passenger from boarding his plane (i.e. mental instability, obvious sickness, drunkeness, etc.). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hypothetically, if someone were being 'forced' take a flight they did not want, what would be the options for the passenger to be refused boarding? I am only interested in the rules for a pilot.&lt;/p&gt;&#xA;" OwnerUserId="2528" LastEditorUserId="2171" LastEditDate="2014-06-03T16:11:55.687" LastActivityDate="2014-06-04T19:08:34.563" Title="What rules would allow a pilot to refuse a passenger's boarding?" Tags="&lt;passenger&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5203" PostTypeId="2" ParentId="5200" CreationDate="2014-06-03T15:20:24.410" Score="24" Body="&lt;p&gt;The answer is probably indeed A. Pegoud with a Bleriot monoplane in the fall of 1913, as answered by RedGrittyBrick. After that, a real craze started in Europe with stunt pilots flying briefly inverted at air shows.&#xA;&lt;P&gt;&#xA;The first purpose-designed airplane for inverted flight was probably a Grade monoplane which flew first in the spring of 1914. I have found this picture &#xA;&lt;img src=&quot;https://i.stack.imgur.com/di3hE.jpg&quot; alt=&quot;Grade Eindecker with landing gear on top and bottom&quot;&gt;&lt;BR&gt;&#xA;on a &lt;a href=&quot;http://flyingmachines.ru/Site2/Arts/Art4713.htm&quot; rel=&quot;noreferrer&quot;&gt;Russian web page&lt;/a&gt; which lists lots of photos from early issues of Flight magazine. You have to scroll down 80% to find it. It gives the name as &quot;Tweer monoplane&quot;, but it was actually built by the Grade aircraft factory right after the inverted flying craze was started by Pegoud. Gustav Tweer was an aerobatics pilot (one of many at this time), who was famous for diving his airplane almost into the ground at flight shows.&#xA;&lt;P&gt;&#xA;This airplane was designed for inverted landings, and with the uncambered wing I would expect that also the fuel system was adapted for inverted flight, however, there is no mention of that anywhere I have searched.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:22:49.113" LastActivityDate="2015-05-07T06:22:49.113" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="5204" PostTypeId="1" AcceptedAnswerId="5206" CreationDate="2014-06-03T17:15:19.273" Score="15" ViewCount="1528" Body="&lt;p&gt;14 CFR 103 compliant powered aircraft should be less than 254 pounds (excluding fuel). Do the &lt;strong&gt;batteries&lt;/strong&gt; account for &lt;strong&gt;fuel&lt;/strong&gt; in case of electric engine?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="69" LastEditDate="2014-06-03T23:40:18.070" LastActivityDate="2020-03-28T17:39:37.613" Title="Does the weight of the battery count as &quot;fuel&quot; in a battery powered ultralight?" Tags="&lt;ultralight&gt;&lt;electric-engine&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5205" PostTypeId="2" ParentId="5197" CreationDate="2014-06-03T17:39:13.353" Score="56" Body="&lt;p&gt;It's possible, but it would be difficult under today's regulations.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Restrictions (regulations):&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Avoid any controlled airspace that requires talking to ATC&lt;/strong&gt;&lt;br&gt;&#xA;For the sake of argument I'll pretend we have no radio on board, so no class B, C, or D airspace.&lt;br&gt;&#xA;(You &lt;strong&gt;&lt;em&gt;COULD&lt;/em&gt;&lt;/strong&gt; call the controlling agency and coordinate with them, but let's just pretend we don't have a cell phone either.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Avoid any airspace within a mode C veil&lt;/strong&gt;&lt;br&gt;&#xA;Because presumably we don't have a transponder on board we can't cross mode C veils.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Avoid any restricted/special use airspace&lt;/strong&gt;&lt;br&gt;&#xA;Duh.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Comply with any other restrictions noted on the chart&lt;/strong&gt;&lt;br&gt;&#xA;I did this in 10 minutes - I may have screwed up a little.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Fuel Reserves&lt;/strong&gt;&lt;br&gt;&#xA;This is the one that makes it tough.&lt;br&gt;&#xA;With no wind 110 miles at 40MPH (the cruise speed) is ~2.75 hours endurance - I assume that's to empty tanks (which is how it's usually quoted for aircraft).&lt;br&gt;&#xA;The FAA requires at least a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?&amp;amp;rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.2.5.31&quot; rel=&quot;noreferrer&quot;&gt;30 minute reserve per FAR 91.155&lt;/a&gt;, which means we can fly for 2.25 hours (90 statute miles, 78.2 nautical miles) before we need to land. All legs need to be under that. (It's possible a flight like this could get a waiver from the FAA, but let's assume nobody applied for one.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Restrictions (Other):&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Refueling&lt;/strong&gt;&lt;br&gt;&#xA;Where possible legs should end at airports that have fuel available.&lt;br&gt;&#xA;(This isn't a hard &quot;must&quot; since presumably the Wright 1B can burn whatever kind of gasoline we can find once we're on the ground).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Airports&lt;/strong&gt;&lt;br&gt;&#xA;I'm excluding private / restricted airports from consideration as landing spots (again, we'll pretend our pilot has no cell phone and therefore can't coordinate landing access at these fields).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Simplifying Assumptions:&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Simple fuel burn&lt;/strong&gt;&lt;br&gt;&#xA;Not having numbers for this aircraft I'm assuming fuel burn will average out such that the aircraft's endurance on all legs is about 2.75 hours (78.2 nautical miles with no wind). This simplifies the planning&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;There is no wind&lt;/strong&gt;&lt;br&gt;&#xA;(Or if there is, it's always a tailwind.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;There's an aviation GPS (or something like Foreflight) onboard&lt;/strong&gt;&lt;br&gt;&#xA;Frankly I wasn't going to spend an hour looking for landmarks.&lt;br&gt;&#xA;You could &lt;em&gt;probably&lt;/em&gt; manage the flight by dead reckoning if you had to though.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The Wright Model B can climb high enough to clear any obstacles/terrain&lt;/strong&gt;&lt;br&gt;&#xA;Again, not having numbers for the aircraft (service/absolute ceiling) I'm just making the assumption to simplify things.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So if we put all that together can we plan this flight?&lt;br&gt;&#xA;&lt;a href=&quot;http://skyvector.com/?ll=43.81570214462621,-112.5751190143963&amp;amp;chart=301&amp;amp;zoom=3&amp;amp;plan=A.K6.31E:G.39.7595691212328,-74.26441954908799:A.K6.N12:F.K6.CASVI:G.40.20048422953527,-74.4099883967534:A.K6.N87:A.K6.N85:A.K6.1N7:A.K6.70N:A.K6.76N:A.K6.N38:A.K6.KBFD:A.K6.KGKJ:A.K5.4G4:G.40.77502983706991,-81.61344909056739:A.K5.KBJJ:G.40.98062378561245,-82.25477599490475:A.K5.5A1:A.K5.KTDZ:G.41.69721828649275,-83.78462218640753:A.K5.KJYM:A.K5.KHAI:A.K5.3TR:A.K5.3HO:A.K5.C56:A.K5.C09:A.K5.KSQI:A.K3.KCWI:A.K3.C17:A.K3.KMIW:A.K3.KEBS:A.K3.KSKI:G.42.49508660000378,-96.37358092743636:A.K3.7K8:A.K3.KLCG:A.K3.KONL:A.K3.KANW:A.K3.KVTN:A.K3.KGRN:A.K3.KCDR:A.K1.KTOR:A.K1.KEAN:A.K1.KLAR:A.K1.KRWL:A.K1.KDWX:A.K2.KCAG:A.K2.4V0:A.K2.KVEL:A.K1.KFBR:A.K1.KEMM:A.K1.KAFO:A.K1.KDIJ:A.K1.KRXE:G.43.79141951497099,-113.05371093337182:A.K1.KAOC:A.K1.KGNG:A.K1.U76:A.K1.KMAN:A.K1.KONO:A.K1.S49:A.K1.KBKE:A.K1.KLGD:A.K1.9S9:A.K1.KDLS:A.K1.4S2:A.K1.KUAO:A.K1.KMMV:A.K1.KONP&quot; rel=&quot;noreferrer&quot;&gt;What do you think I did with the first half of my lunch hour?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/11d56.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/11d56.jpg&quot; alt=&quot;Route Overview&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;sub&gt;This is one possible route - there may of course be others&lt;/sub&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe I met all the restrictions, if I screwed up I'm sure someone will edit the flight plan (or come up with a different route).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A Note on Performance&lt;/strong&gt;&lt;br&gt;&#xA;As I mentioned in the assumptions I didn't have performance data available for the 1B when I laid out this route. Some folks helpfully pointed out in comments that there are &lt;a href=&quot;https://aviation.stackexchange.com/questions/5197/could-the-wright-brothers-fly-across-the-us-today/5205#comment10675_5197&quot;&gt;flying replicas of the 1B&lt;/a&gt;.  These don't appear to be &quot;exact reproduction&quot; replicas, but I was able to find &lt;a href=&quot;http://www.wright-b-flyer.org/aircraft/brown-bird.html&quot; rel=&quot;noreferrer&quot;&gt;some performance data on them&lt;/a&gt;.&lt;br&gt;&#xA;Given the maximum altitude in the performance figures (2,000 feet MSL) it would probably not be possible to fly the route plotted above with the reproduction equipment available (several legs are well above 2,000 feet MSL), and I would assume the original 1B had comparable performance.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-06-04T18:40:13.013" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="5206" PostTypeId="2" ParentId="5204" CreationDate="2014-06-03T22:46:50.247" Score="14" Body="&lt;p&gt;The jury (i.e. FAA) is still out on this question as of early June 2014.  FAA has indicated it will not give a gasoline &quot;fuel allowance&quot; to be credited against weight for batteries.  Given that fuel weighs 6 lbs. per gallon, or 30 lbs. for the maximum legal gas an ultralight can carry, it would be a somewhat negligible, but certainly welcome, allowance for would-be electric manufacturers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One company, Chip Erwin of AeroMarine, has imported a barebones ultralight motorglider based on the Goat towed ultralight glider.  It's called the &lt;a href=&quot;http://youtu.be/bYEYqHR6Mc0&quot; rel=&quot;noreferrer&quot;&gt;Zigolo&lt;/a&gt;, and carries batteries enough for 30-40 mins. of flight, without exceeding the 254-lb. weight limit of the part 103 category.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In time the FAA may well decide to grant the allowance.  It's still not going to amount to much more time, maybe 10 minutes given current battery energy density, which is a fraction of the energy density of gasoline, but research into electric storage is at a feverish pace worldwide.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look for sport, then commercial electric aircraft, within the next 5 to 10 years.  Several electric single and two-seat electrics are already flying.  The Airbus ducted fan, recently ballyhooed as the first electric aircraft, which it certainly isn't, is a promising look at one way commercial electric applications might come to market.&lt;/p&gt;&#xA;" OwnerUserId="2534" LastEditorUserId="64" LastEditDate="2014-06-04T21:34:11.017" LastActivityDate="2014-06-04T21:34:11.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5207" PostTypeId="2" ParentId="5197" CreationDate="2014-06-04T13:30:48.933" Score="14" Body="&lt;p&gt;If Orville and Wilbur reappeared today, along with the original Flyer, I expect the FAA would issue an exemption to pretty much everything in about 5 minutes. Also, every pilot in the hemisphere would be watching rather than working thus eliminating the conflicting-traffic issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, they would have a problem starting around 105 West - small geographical inconvenience called the Rocky Mountains. You could possibly pick a route through various valleys but it's unlikely the original design (engine or airfoil) would work at that altitude. And one good gust of wind down the valley will knock it right out of the sky. History might have been quite different if the Wrights were from Denver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take the Wrights for a spin in an SR-71 instead. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-04T13:30:48.933" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5208" PostTypeId="2" ParentId="5032" CreationDate="2014-06-04T17:15:34.400" Score="7" Body="&lt;p&gt;Another good reference would be the &lt;a href=&quot;http://www.vatusa.net/training/tiki-index.php?page=Basic%20ATC&quot; rel=&quot;nofollow&quot;&gt;training materials&lt;/a&gt; for VATUSA. This is part of an online system called VATSIM where people both fly and provide ATC virtually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although some of it does not apply to real operations (and of course none of it should be actual operations), it still covers real procedures based on the actual rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic guides do a good job of providing an introduction to the basic concepts, but the more advanced stuff is less helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other regions have their own VATSIM organizations, if you prefer a region other than the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the materials available, participation is also great for learning. Through VATSIM you can get training on the materials and then get hands-on experience working with (virtual) traffic.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-05T16:25:33.123" LastActivityDate="2014-06-05T16:25:33.123" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5209" PostTypeId="2" ParentId="3814" CreationDate="2014-06-04T17:28:48.250" Score="0" Body="&lt;p&gt;Well, the absolute cheapest and easiest way for aerial video is with a homemade garbage bag kite. Don't laugh, sometimes you can get great results. And you can easily change the viewpoint angle by simply reeling the kite in, adjusting the camera to a different view angle, and reeling it back out. You can also fly all day as long as you got wind.  Here's how. &#xA;&lt;a href=&quot;http://quadcopter101.blogspot.com/2014/04/do-you-wish-to-do-aerial-video-but-only.html&quot; rel=&quot;nofollow&quot;&gt;http://quadcopter101.blogspot.com/2014/04/do-you-wish-to-do-aerial-video-but-only.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But another cheap and easy way is with a toy quadcopter.  And again you can get surprisingly good results with even the cheapest (about $65) quadcopters.  Again, here's how:&#xA;&lt;a href=&quot;http://quadcopter101.blogspot.com/2014/02/misc-4-aerial-video-part-2.html&quot; rel=&quot;nofollow&quot;&gt;http://quadcopter101.blogspot.com/2014/02/misc-4-aerial-video-part-2.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2545" LastActivityDate="2014-06-04T17:28:48.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5210" PostTypeId="2" ParentId="5202" CreationDate="2014-06-04T19:08:34.563" Score="8" Body="&lt;p&gt;The regulation that springs immediately to mind is FAR 91.17(b):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner or physical indications that the individual is under the influence of drugs (except a medical patient under proper care) to be carried in that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;i.e. &quot;If you get yourself blind stinking drunk at the airport bar, or you've been doing lines of cocaine in the airport bathroom you are &lt;em&gt;not&lt;/em&gt; getting on the plane because the FAA says I can't let you.&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For other cases you need to head over to &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/USCODE-2011-title49/html/USCODE-2011-title49-subtitleVII-partA-subpartiii-chap449-subchapI-sec44902.htm&quot;&gt;49 USC 44902&lt;/a&gt;, which deals with Refusal to transport passengers and property for &quot;air carriers&quot; (FAR part 121, and I believe 135 operations are covered by this bit of the US Code). The most relevant text is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Permissive Refusal.&lt;br&gt;&#xA;  Subject to regulations of the Under Secretary, an air carrier, intrastate air carrier, or foreign air carrier may refuse to transport a passenger or property the carrier decides is, or might be, inimical to safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most air carriers vest the captain with the decision-making authority here: If the captain determines that a passenger may be &quot;inimical to safety&quot; they can refuse to fly the passenger.  There are some restrictions on that authority - notably that the basis for the decision can't be &quot;discriminatory&quot; - which are scattered about in 14CFR (the FARs) and 49USC (Transportation), as well as case law. The FAA has issued &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2002/jamesjohnson%20-%20%282002%29%20legal%20interpretation.pdf&quot;&gt;at least one legal interpretation&lt;/a&gt; discussing this in more detail.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For commercial (or non-commercial) operations under part 91 I wasn't able to find anything specific in 14CFR or 49USC, but in those cases the general consensus seems to be that the PIC has at least the level of authority granted under 49USC44902 - if not broader authority (i.e. if you're going on a personal flight you could refuse to take someone along because you don't like their shoes, and if someone hires you for a commercial flight you could refuse the job if they were acting sketchy).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-04T19:08:34.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5211" PostTypeId="2" ParentId="5197" CreationDate="2014-06-05T04:17:29.260" Score="2" Body="&lt;p&gt;The below answer is &lt;strong&gt;probably wrong&lt;/strong&gt;.  I had thought the elevation at the Continental Divide (at least 4421 feet) would be an obstacle.  However, according to &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_altitude_record&quot; rel=&quot;nofollow&quot;&gt;Wikipedia's list of altitude records&lt;/a&gt;, an aircraft described as a &quot;Wright biplane&quot; reached an altitude of 8471 feet in October 1910.  It is unclear exactly what model was used, though from the date it was very likely a Model B or some variant thereof.  It could have been a &lt;a href=&quot;http://en.wikipedia.org/wiki/Wright_Model_R&quot; rel=&quot;nofollow&quot;&gt;Model R&lt;/a&gt;, which appears to have been a high-performance variant of the Model B, &quot;designed for speed and altitude competitions&quot;; apparently two examples of the Model R were present at the 1910 International Aviation Tournament where the 8471-foot record was set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll leave this answer here for a couple days for the correction, then delete it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Original answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;s&gt;&lt;strong&gt;No, they could not.&lt;/strong&gt;&lt;/s&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Piggybacking on the data found by voretaq7 and following the issue noticed by paul and gabe: according to &lt;a href=&quot;http://www.wright-b-flyer.org/aircraft/brown-bird.html&quot; rel=&quot;nofollow&quot;&gt;this data&lt;/a&gt;, a similar aircraft has a maximum altitude of about 2000 feet MSL.  On the other hand, according to &lt;a href=&quot;http://mcfarren.info/adam/outdoor/cd/&quot; rel=&quot;nofollow&quot;&gt;this table&lt;/a&gt;, the lowest elevation on the Continental Divide in the US is 4421 feet.&lt;/p&gt;&#xA;" OwnerUserId="2546" LastEditorUserId="2546" LastEditDate="2014-06-05T04:56:58.407" LastActivityDate="2014-06-05T04:56:58.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5213" PostTypeId="1" AcceptedAnswerId="5217" CreationDate="2014-06-05T07:40:59.030" Score="19" ViewCount="7284" Body="&lt;p&gt;During the initial era of air travel how do the pilots/Navigation officers would communicate with ground stations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they use radio communication? Or Telegraph was used?&lt;/p&gt;&#xA;" OwnerUserId="1337" LastEditorUserId="62" LastEditDate="2016-04-06T12:44:51.080" LastActivityDate="2016-04-06T12:44:51.080" Title="How did aircraft communicate during early air travel?" Tags="&lt;radio-communications&gt;&lt;aviation-history&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5214" PostTypeId="1" AcceptedAnswerId="5216" CreationDate="2014-06-05T08:18:18.387" Score="10" ViewCount="103" Body="&lt;p&gt;Is there a way to (safely) calculate the stall speed of an aircraft ($V_{S0}$) for anything below maximum weight? All the tables in the POH are valid for maximum weight only, and stall speed can drop significantly with a light load. As a consequence, if you're flying the published (max weight) $V_{ref}$ on final, you'll actually be carrying a significant amount of extra speed and thus increase the required landing distance, possibly in quite a dramatic fashion.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="19" LastEditDate="2016-06-22T07:58:07.127" LastActivityDate="2016-06-22T07:58:07.127" Title="How is V_S0 calculated for anything less than maximum weight?" Tags="&lt;approach&gt;&lt;airspeed&gt;&lt;stall&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5215" PostTypeId="2" ParentId="5213" CreationDate="2014-06-05T08:25:35.580" Score="13" Body="&lt;p&gt;While radio was available (meaning it existed) it did not exist in a form usable by early aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are talking early-early travel, not commercial travel, communication was not necessary. Navigate to the destination, circle the (farmer's) field to check for livestock, then land. Communication with other aircraft was not necessary as there usually were no other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As things progressed, morse code became practical. This was when cockpit crews required both hands to count.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-05T08:25:35.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5216" PostTypeId="2" ParentId="5214" CreationDate="2014-06-05T09:41:57.517" Score="9" Body="&lt;p&gt;All aerodynamic forces are proportional to the dynamic pressure, which is the product of air density $\rho$ and half of the square of flight speed $\frac{1}{2}v^2$. If your flight mass is reduced, reduce the dynamic pressure proportionally to keep all other parameters the same. To express this in terms of speed, you need to multiply the posted speed in the handbook with the square root of the mass ratio, like that: $$v_{reduced\,mass} = v_{full\,mass}\cdot\sqrt{\frac{reduced\,mass}{original\,mass}}$$&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-06-05T09:41:57.517" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5217" PostTypeId="2" ParentId="5213" CreationDate="2014-06-05T09:58:10.647" Score="22" Body="&lt;p&gt;Radio was not widely used until the 1930s, before that, mostly light signals were used. Early ground support aircraft in WW I could drop little notes which were pencilled by the observer, stuffed in a small capsule to which a streamer was fitted, and that was dropped as closely as possible to the troops which should get that message. This method was still used in WW II, when most aircraft had radio, because only specially equipped ground troops had compatible receivers.&#xA;&lt;P&gt;&#xA;The first regular flights by night were 1921 for the air mail connection between Omaha and Chicago, and electric flood lights were positioned along the flight path.&#xA;When Lufthansa opened the first night connection between the Reich and East Prussia in 1926, they posted burning oil drums along the way to mark where the pilot had to fly. Communication the other way (air to ground) was not possible on those flights.&#xA;&lt;P&gt;&#xA;The first air-to-ground radio communication used morse signals, and this is the origin for these strange three-letter names for things like local air pressure at the ground (QFE) or pressure corrected to sea level conditions (QNH). There was a whole lot more of those, including some to order coffee before landing, but they are no longer necessary. &lt;a href=&quot;http://en.wikipedia.org/wiki/Q_code&quot;&gt;Read all about it here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-06T09:41:24.567" LastActivityDate="2014-06-06T09:41:24.567" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5218" PostTypeId="1" CreationDate="2014-06-05T10:24:06.903" Score="12" ViewCount="2450" Body="&lt;p&gt;My son in law took these images a few days ago in Culver City California. We would like to know what the vintage (WWII ?) planes are, and in the last image, what would cause such a contrail. The last image is a composite of several shots. (Something landing at Edwards was my guess). His guess for the aircraft are that they are all the &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_SBD_Dauntless&quot; rel=&quot;nofollow noreferrer&quot;&gt;DB Dauntless&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zzLJ5.jpg&quot; alt=&quot;Formation of six planes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DonhQ.jpg&quot; alt=&quot;Formation of six planes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LYpZU.jpg&quot; alt=&quot;Formation of six planes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Mh6Bq.jpg&quot; alt=&quot;Composite of images showing curved contrail&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2550" LastEditorUserId="1696" LastEditDate="2015-02-20T23:02:09.337" LastActivityDate="2019-03-18T20:34:41.517" Title="What type are these planes that are flying in formation near Culver City, CA?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5220" PostTypeId="2" ParentId="5218" CreationDate="2014-06-05T11:02:20.993" Score="20" Body="&lt;p&gt;My (current) guess is that it may be a &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Nanchang CJ-6&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Nanchang CJ-6 is an aircraft designed and built in China for use&#xA;  by the People's Liberation Army Air Force (PLAAF) as a basic trainer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Round nose.&lt;/li&gt;&#xA;&lt;li&gt;Sufficient number airworthy. &lt;/li&gt;&#xA;&lt;li&gt;Rectangular wing shape.&lt;/li&gt;&#xA;&lt;li&gt;Main gear folds inwards and the nosegear backwards which seems to fit when I zoom in your pictures.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Nanchang_CJ-6A_Airplane_over_California_Coastline_N4183E_20110219.jpg/1280px-Nanchang_CJ-6A_Airplane_over_California_Coastline_N4183E_20110219.jpg&quot; alt=&quot;yak52&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and they do airshows:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Lo74Y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lo74Y.jpg&quot; alt=&quot;airshow&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://www.riversideca.gov/airshow/images/CJ6A%20Nanchang.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;riversideca.gov&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coincidentally, the upper-left aircraft #43 also appears in your pictures (first picture, rightmost aircraft). Another below of her below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i1.ytimg.com/vi/dlPYqTT0KaU/maxresdefault.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;update&lt;/strong&gt;: as Cardinal said above, &quot;This is likely &lt;a href=&quot;http://www.tigersquadron.com/Formation-Flying-Air-Shows-Los-Angeles-CA.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tiger Squadron&lt;/a&gt;, perhaps flying for the Israel Independence Day Festival over Rancho Park in mid May, as detailed on their &lt;a href=&quot;https://www.facebook.com/TigerSquadronRPA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Facebook page&lt;/a&gt;.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-18T20:34:41.517" LastActivityDate="2019-03-18T20:34:41.517" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="5221" PostTypeId="1" AcceptedAnswerId="5222" CreationDate="2014-06-05T13:06:52.103" Score="10" ViewCount="2051" Body="&lt;p&gt;Once ATC have assigned me a holding pattern, how do I determine where to intercept it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And once that I have determined the intercept point, how do I proceed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard about the teardrop and the parallel entries, are there others? How do I select the most appropriate entry?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the intercept maneuver, can I assume[1] that the appropriate airspace is free (since ATC told me to intercept that hold) or there is high risk of coming close to other aircrafts?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[1] this does not mean that I will not look at the radar/out of the window, is just to know the level of attention that I have to pay to this aspect.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="2" LastEditDate="2014-06-05T13:10:03.920" LastActivityDate="2014-06-06T08:30:09.703" Title="How to properly enter a holding pattern?" Tags="&lt;holding&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5222" PostTypeId="2" ParentId="5221" CreationDate="2014-06-05T13:42:23.080" Score="12" Body="&lt;p&gt;to source &lt;a href=&quot;http://en.wikipedia.org/wiki/Holding_pattern#Entry_procedures&quot; rel=&quot;noreferrer&quot;&gt;from wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are three standard types of entries: direct, parallel, and&#xA;  offset (teardrop). The proper entry procedure is determined by the&#xA;  angle difference between the direction the aircraft flies to arrive at&#xA;  the beacon and the direction of the inbound leg of the holding&#xA;  pattern.&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A &lt;strong&gt;direct entry&lt;/strong&gt; is performed exactly as it sounds: the aircraft flies directly to the holding fix, and immediately begins the first turn&#xA;  outbound.&lt;br&gt;&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/DWryI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;  &lt;li&gt;In a &lt;strong&gt;parallel entry&lt;/strong&gt;, the aircraft flies to the holding fix, parallels the inbound course for one minute outbound, and then turns&#xA;  back, flies directly to the fix, and continues in the hold from there.&lt;br&gt;&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/L7L2y.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;  &lt;li&gt;In an &lt;strong&gt;offset&lt;/strong&gt; or &lt;strong&gt;teardrop entry&lt;/strong&gt;, the aircraft flies to the holding fix, turns into the protected area, flies for one minute, and then&#xA;  turns back inbound, proceeds to the fix and continues from there.&lt;br&gt;&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/2DagX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see the maneuvers are all inside the area circumscribed by the holding pattern (not counting flying directly to the holding fix) so you can assume the airspace is clear at your altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Important to note is that you should fly directly to the beacon and then reorient yourself as appropriate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airport approach charts will indicate where the beacons/landmarks are located, which code they use and which heading the &quot;inbound&quot; leg (when flying towards the beacon) has.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="247" LastEditDate="2014-06-06T08:30:09.703" LastActivityDate="2014-06-06T08:30:09.703" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5224" PostTypeId="2" ParentId="5213" CreationDate="2014-06-05T18:24:32.633" Score="5" Body="&lt;p&gt;Up until World War One, there was no radio communication between air and ground, or between planes. Communication from ground to air was done by means of light signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From 1915 onwards aircraft were used as artillery spotters &lt;a href=&quot;http://www.firstworldwar.com/airwar/observation.htm&quot;&gt;which involved Morse code wireless signals one-way&lt;/a&gt;,  (from the aircraft to the ground). There was no communication from ground to air, and the air-to-ground communication was limited to simple codes. The only form of air-to-air communications was signals such as 'wing-waggling'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air-to-ground and air-to-air spoken radio communication became common between the wars, and was widespread in major air forces at the start of it.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2014-06-05T18:41:05.893" LastActivityDate="2014-06-05T18:41:05.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5225" PostTypeId="1" CreationDate="2014-06-05T19:02:22.120" Score="10" ViewCount="1541" Body="&lt;p&gt;Looking at the ATC transcript from MH370, I noticed that nowhere is the QNH communicated to the aircraft. That seemed odd to me... it seems that every time I talk to a tower or airways they tell me what the QNH is in their location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is it normal for airliners to not be told what the QNH is before takeoff? Or in communications with DEPARTURE or RADAR?&lt;/p&gt;&#xA;" OwnerUserId="2553" LastEditorUserId="572" LastEditDate="2015-02-19T09:28:21.080" LastActivityDate="2015-02-19T09:28:21.080" Title="Why does the MH370 ATC transcript never mention QNH? When is QNH given to aircraft?" Tags="&lt;air-traffic-control&gt;&lt;airliner&gt;&lt;mh370-incident&gt;&lt;qnh&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5226" PostTypeId="2" ParentId="5225" CreationDate="2014-06-05T19:13:01.180" Score="14" Body="&lt;p&gt;Airline pilots generally get the QNH from the airport ATIS or similar. If they don't get it from there, ground control will give it before taxi.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above the transition level (&lt;a href=&quot;http://aip.dca.gov.my/aip%20pdf/ENR/ENR%201/ENR%201.7/Altimeter%20Setting%20Procedures.pdf&quot; rel=&quot;nofollow&quot;&gt;11,000 feet&lt;/a&gt; (3,350 m) in Malaysia, 18,000 feet in the US), the altimeter is set to the standard pressure (29.92 inHg, 1013 hPa), also referred to as QNE. It doesn't take that long to climb through this point, so they would keep the departure QNH set until reaching the transition altitude. They won't need to set it again until they begin their descent near their destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So after setting it before taxi, the next time they would need it is on approach before they descend below the transition level. Again, they can get the ATIS from their arrival airport for QNH. If not, the approach controller will give them the QNH.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-06T17:48:45.763" LastActivityDate="2014-06-06T17:48:45.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5227" PostTypeId="2" ParentId="5218" CreationDate="2014-06-05T21:38:40.233" Score="0" Body="&lt;p&gt;That looks like the Red Stars Aerobatic Team - they fly Yak-52s&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Yakovlev_Yak-52&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Yakovlev_Yak-52&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard to tell from your picture, but the overall look of the team itself, the prominent red stars on one of them, and the rounded tail make me think that's who it is. I tried to find their schedule and see if they would have been in your area, but they apparently don't have a web site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a video I shot of them in 2009 - &lt;a href=&quot;https://www.youtube.com/watch?v=0A5qYqcQsxw&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=0A5qYqcQsxw&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK yes... I found their site. Looks like they had an event in CA this weekend, but not very close to you, and the event was cancelled... so they might have been flying around for fun and practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flyredstar.org/calendar.php&quot; rel=&quot;nofollow&quot;&gt;http://flyredstar.org/calendar.php&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2554" LastActivityDate="2014-06-05T21:38:40.233" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="5229" PostTypeId="2" ParentId="5213" CreationDate="2014-06-05T23:05:53.743" Score="2" Body="&lt;p&gt;Military aircraft frequently used radiotelegraphy (Morse code) well into WWII, if not 'til the end. The binary nature of it (on/off constant amplitude signal*) gave greater effective range and more resistance to degradation by static than radiotelephony (voice). Most aircraft had voice radios for communication with nearby friendly aircraft and bases, but relied on Morse code at long ranges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;* shades of digital transmissions today!&lt;/p&gt;&#xA;" OwnerUserId="1078" LastActivityDate="2014-06-05T23:05:53.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5230" PostTypeId="1" CreationDate="2014-06-06T10:31:30.477" Score="4" ViewCount="16263" Body="&lt;p&gt;I have found only the description of this pattern with experimental graphs.Could anyone please tell me the mathematical formula required to plot the distribution?&lt;/p&gt;&#xA;" OwnerUserId="2558" LastActivityDate="2017-04-26T12:25:14.053" Title="How to plot the pressure distribution over an airfoil?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5231" PostTypeId="2" ParentId="5230" CreationDate="2014-06-06T11:12:14.267" Score="10" Body="&lt;p&gt;&lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;noreferrer&quot;&gt;XFoil&lt;/a&gt; uses two ways of plotting pressure distributions, one with the chord coordinate on the X axis and the negative pressure coefficient $c_p$ on the Y axis, like that:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/JweA2.png&quot; alt=&quot;Cp plot over chord of an Eppler 502 mod&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dashed line is for inviscid flow (from the potential flow solver), the solid line for pressure with boundary layer effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another version plots the pressure as arrows orthogonally on the contour of the airfoil, like that:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3f72x.png&quot; alt=&quot;Same airfoil, now with arrows to indicate pressure&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that negative values of $c_p$ produce arrows pointing away from the airfoil, and positive values point towards the airfoil. In all cases, the formula for $c_p$ is $$c_p = \frac{p - p_{\infty}}{q_{\infty}}$$&#xA;$p$ is the local pressure, $p_{\infty}$ is the pressure far away from the airfoil, and $q_{\infty}$ is the dynamic pressure far away from the airfoil.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:24:14.403" LastActivityDate="2015-05-07T06:24:14.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5232" PostTypeId="2" ParentId="5230" CreationDate="2014-06-06T11:17:34.217" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I have found only the description of this pattern with experimental graphs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's because that is the best way to have detailed and precise data: you either simulate (e.g., with Nastran-Patran or XFoil, as cited by Peter Kämpf in his &lt;a href=&quot;https://aviation.stackexchange.com/a/5231/1467&quot;&gt;answer&lt;/a&gt;) or build a [scale] model and use a wind tunnel. If you use a scale model, depending on the focus of the experiment, you will have to be careful (while scaling back up) not to damage your data: for this you have adymensional quantities to look after, such as the Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Could anyone please tell me the mathematical formula required to plot the distribution?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is not one formula to do that, but rather a method that given the airfoil shape (and the angle of attack) will estimate the pressure distribution. This method was extensively used in the days before computers and FEM tools existed (for what I know SR71 is a notable example where this method has been used in the early phase of the wings design), but, for what I know, nowadays is seldom used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The method is based on &lt;a href=&quot;http://mathworld.wolfram.com/ConformalMapping.html&quot; rel=&quot;noreferrer&quot;&gt;Conformal Mapping&lt;/a&gt;, in particular the &lt;a href=&quot;http://en.wikipedia.org/wiki/Joukowsky_transform&quot; rel=&quot;noreferrer&quot;&gt;Joukowsky transform&lt;/a&gt; or the Kármán–Trefftz for more detailed and general cases (see &lt;a href=&quot;http://www.math.washington.edu/~morrow/336_13/papers/thomas.pdf&quot; rel=&quot;noreferrer&quot;&gt;Sec. 4.2 of this pdf&lt;/a&gt; for a more in-depth explanation). This is a transformation in the complex plane that, from the airfoil profile that you want to analyse, will &lt;em&gt;map&lt;/em&gt; it onto a circle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You want to do this because the ideal flow around a circle is well known:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/iton7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point you have to know that around an airfoil the air will have a certain amount of circulation and that the total flow around it is the sum of the ideal unviscous flow plus the flow induced by the circulation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tASQv.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt; Image from &lt;a href=&quot;http://web.mit.edu/2.972/www/reports/airfoil/airfoil.html&quot; rel=&quot;noreferrer&quot;&gt;MIT&lt;/a&gt; &lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason, you want to compute the ideal flow around a cilinder that has a rotation speed equivalent to the circulation around your airfoil[*]:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lCUYF.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and it turns out that &lt;a href=&quot;http://nptel.ac.in/courses/Webcourse-contents/IIT-KANPUR/FLUID-MECHANICS/lecture-23/23-2_flow_rotate_cylinder.htm&quot; rel=&quot;noreferrer&quot;&gt;we have some formulas&lt;/a&gt; for that (image above taken from this page).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;[*]: note that you will have different circulations for different angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, why did we do all this? Because once we have the flow around the rotating cilinder and &#xA;we have the mapping from the airfoil to the cylinder, &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/map.html&quot; rel=&quot;noreferrer&quot;&gt;we &quot;only&quot; have to invert the mapping&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N6Eoz.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and we immediately have our flow around the airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And once we have the airflow, finding the pressure distribution is quite straightforward, thanks to &lt;a href=&quot;http://www.princeton.edu/~asmits/Bicycle_web/Bernoulli.html&quot; rel=&quot;noreferrer&quot;&gt;Bernoulli&lt;/a&gt; (you have the velocity distribution and you can assume that the transit of the air around the wing is fast enough to be &lt;a href=&quot;http://en.wikipedia.org/wiki/Adiabatic_process&quot; rel=&quot;noreferrer&quot;&gt;adiabatic&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-06-06T11:48:00.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5233" PostTypeId="1" CreationDate="2014-06-06T11:35:10.440" Score="10" ViewCount="1227" Body="&lt;p&gt;I just finished watching National Geographic's &lt;a href=&quot;http://www.youtube.com/watch?v=IjpW0TTc_a8&quot;&gt;Megafactories: Boeing 747-8&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the test flights, a bunch of engineers are on board the plane, presumably controlling the water tanks that distribute weight, and collecting the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another time I'd seen it was when they were testing &lt;a href=&quot;http://er.jsc.nasa.gov/seh/pg56s95.html&quot;&gt;detection systems for microbursts&lt;/a&gt;. There were about a dozen engineers sitting on the plane, watching monitors while the crew deliberately flew into hazardous conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do they risk the safety of these engineers, when presumably the work they're doing could be automated or controlled remotely? For data to be observed, couldn't they do that from the ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this a case of &quot;we've always done it this way?&quot; Even now that we probably have the technology that would allow the engineers to avoid having to go on test flights, I'm guessing that changing this procedure would be a lengthy and difficult process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides the pilots, why does anyone else need to be on board?&lt;/p&gt;&#xA;" OwnerUserId="1579" LastActivityDate="2018-01-01T13:20:42.443" Title="Why do the engineers need to be on board during testing?" Tags="&lt;safety&gt;&lt;flight-testing&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5234" PostTypeId="2" ParentId="5233" CreationDate="2014-06-06T11:59:53.983" Score="7" Body="&lt;p&gt;In a perfect world, you wouldn't need the pilots as well...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To your question:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;No modern instrument can currently match the feeling of &quot;just being there&quot;.&lt;/li&gt;&#xA;&lt;li&gt;Data recorded on the plane and transmitted to the tower is lagging or even impossible to collect live (due to technical difficulties).&lt;/li&gt;&#xA;&lt;li&gt;Flying takes a lot of attention from the pilot. Even if they're good engineers (besides being a pilot), you wouldn't want to waste an experiment.&lt;/li&gt;&#xA;&lt;li&gt;Engineers don't go to preliminary (dangerous) flight test.&lt;/li&gt;&#xA;&lt;li&gt;Some engineers enjoy being on board the machine they designed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2560" LastActivityDate="2014-06-06T11:59:53.983" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="5235" PostTypeId="1" AcceptedAnswerId="5238" CreationDate="2014-06-06T15:47:02.163" Score="15" ViewCount="3755" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5221/how-to-properly-enter-a-holding-pattern&quot;&gt;This&lt;/a&gt; question prompted me to wonder how it works at a major airport. Let's say four airliners all are scheduled to arrive within a few minutes of each other to a major airport, perhaps from the four cardinal directions. Things are already backed up at the airport, let's say landings are (temporarily) restricted due to an emergency landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you describe how ATC might direct the four flights and what they would do themselves?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-06-06T20:25:11.717" Title="How do airplanes get stacked in a holding pattern?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;commercial-aviation&gt;&lt;airport&gt;&lt;holding&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5236" PostTypeId="2" ParentId="5235" CreationDate="2014-06-06T16:19:51.940" Score="5" Body="&lt;p&gt;First come first serve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically ATC will direct the first plane to the lowest free altitude in the holding pattern and the next 1000 ft on top of that and so on. It may be possible that a plane comes in at a lower altitude right after a plane at a higher one and gets to skip to a lower spot (so it doesn't need to climb up).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the runway/next segment is available ATC will clear the lowest plane to continue/land and then shift the entire stack down.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-06-06T16:19:51.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5237" PostTypeId="2" ParentId="5233" CreationDate="2014-06-06T16:36:56.643" Score="8" Body="&lt;p&gt;More and more data is collected in flight testing of aircraft. While 50 years ago they might have only designed for a small number of scenarios, the advances in computing allow them to design modern aircraft for thousands of scenarios. Modern certification standards include more and more requirements, which include flight testing for many of these requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While some information is sent to the ground (like in &lt;a href=&quot;http://videos.airbus.com/video/a63c716fd80s.html&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;), other information may not be. Airplanes in flight test have sensors for temperature, pressure, stress, and many other parameters located throughout the plane. These generate a lot of data, more than may be practical to send on a live data link. There may be several reasons that the engineers would want to analyze a lot of information onboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the tests need to have multiple parameters coordinated with the pilots. If they are flight testing stall, for instance, they need to be sure they have flight parameters are correct for that test. The engineers give the pilots guidance on getting the airplane into the right configuration. The engineers also verify that the the information they collect is sufficient for the needs of the test. It's much more expensive to come back and realize they didn't get what they needed and must go back up to re-run the test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the data is also critical for safety. One subject of the tests is flutter. Flutter conditions can be &lt;a href=&quot;http://www.youtube.com/watch?v=kQI3AWpTWhM&quot; rel=&quot;noreferrer&quot;&gt;very dangerous to the aircraft&lt;/a&gt;. The engineers help monitor the data and make sure that things don't get out of hand. If a data link were to be interrupted in a case like this, safety could be compromised.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-06T16:36:56.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5238" PostTypeId="2" ParentId="5235" CreationDate="2014-06-06T17:00:04.517" Score="13" Body="&lt;p&gt;ATC has many tools &quot;in their belt&quot; to keep traffic separated. When things back up, it can get crowded. Emergencies and weather regularly cause disruptions and ATC handles them according to the circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate some possibilities, I will use &lt;strong&gt;Seattle&lt;/strong&gt; as an example here. You can find the airport information &lt;a href=&quot;http://www.airnav.com/airport/KSEA&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft coming into the area will be commercial flights on IFR flight plans, and they will follow a Standard Terminal Arrival (STAR) into Seattle. You can find this seciton towards the bottom of the AirNav page. There are different STARs depending on the direction from which the flight is arriving. Each STAR will include published holding patterns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Listed here is the direction of arrival, the name of the STAR, and the holding fixes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;East - EPHRATA - FLAAK, EPHRATA, ODESS&lt;/li&gt;&#xA;&lt;li&gt;East - GLASR - LOSTT, TEMPL, JAKSN&lt;/li&gt;&#xA;&lt;li&gt;Southeast - CHINS - SUNED, BRUKK&lt;/li&gt;&#xA;&lt;li&gt;South - OLYMPIA - BTG, OLYMPIA&lt;/li&gt;&#xA;&lt;li&gt;Southwest - HAWKZ - BTG, HAWKZ&lt;/li&gt;&#xA;&lt;li&gt;Northwest - JAWBN - JAWBN&lt;/li&gt;&#xA;&lt;li&gt;Northwest - MARNR - MARNR&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As you can see, there are 11 different holding fixes across the seven STARs. If you have one aircraft from each direction, they can each hold at the fix according to their STAR. The busiest STARs have multiple holding fixes that may be used. Aircraft may also be stacked on the same hold at different altitudes. You can read some FAA information about holds &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7130.3A.pdf&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft may also choose to divert. Depending on how much fuel they have and how the weather/emergency is playing out, they may not want to hold indefinitely on the GLASR arrival at LOSTT. Generally ATC will not ask for a diversion unless absolutely necessary. Among others, Portland, Vancouver, and Spokane are all fairly close to where the aircraft may be holding and could be viable alternates.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-06T17:00:04.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5239" PostTypeId="1" AcceptedAnswerId="5242" CreationDate="2014-06-06T17:33:16.417" Score="7" ViewCount="2570" Body="&lt;p&gt;Ignoring for a moment potential schematic difficulties in creating an aircraft that can land and take-off without threatening a downward vertical stabilizer, would a vertical stabilizer that extends both above and below the aircraft's centerline improve or hinder in-flight stability?&lt;/p&gt;&#xA;" OwnerUserId="2471" LastActivityDate="2014-06-19T07:44:35.220" Title="Would a vertical stabilizer that extends both above and below the centerline be benefit or hindrance?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5240" PostTypeId="2" ParentId="5225" CreationDate="2014-06-06T17:37:44.987" Score="2" Body="&lt;p&gt;QNH and other airport information is communicated to incoming flights through &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service&quot; rel=&quot;nofollow&quot;&gt;ATIS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only acknowledgement of this you will hear through ATC is aircraft first contacting the controller saying &quot;with information Oscar&quot; or similar, which means they have already heard the ATIS bulletin.&lt;/p&gt;&#xA;" OwnerUserId="289" LastActivityDate="2014-06-06T17:37:44.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5241" PostTypeId="2" ParentId="5235" CreationDate="2014-06-06T18:04:23.830" Score="6" Body="&lt;p&gt;As @fooot mentions, most, if not all, holding will take place at fixes along the arrival, not within the terminal airspace.  Once airplanes are being controlled by an approach facility they will resolve spacing issues with vectors.  Altitude changes within this airspace can be difficult (see: NY Tracon) and the airspace requirements for holding make it quite inefficient.  Once approach runs out of room to properly sequence with vectors, they'll use their landlines to call the controller at the center feeding the arrivals and tell them &quot;We're closed -- update at 2130Z&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The center will then start the holds.  Aircraft that are closest to being handed off will be assigned the holding at the closest fixes to the destination.  This usually means holding at low altitudes (E.g. holding over Yardley at 8000 ft inbound to EWR).  Aircraft further back will either get a hold close to them, or they'll continue the arrival and hold toward the end.  These decisions are based on airspace availability and how long the anticipated holding will be.  Where center has altitude blocks available, they'll stack aircraft at that fix.  I've been in holding at FL240 where I have seen 10-12 airplanes below me and a few above me, all flying the same racetrack spaced 1000' vertically.  When arrivals resume ATC will peel airplanes off the bottom of the hold, one at at time at intervals dependent on the spacing requested by the approach facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If delays become long, aircraft will begin to divert to their alternates, refuel and then wait under a ground stop or ground delay to get back in the air to their final destination.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-06-06T20:25:11.717" LastActivityDate="2014-06-06T20:25:11.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5242" PostTypeId="2" ParentId="5239" CreationDate="2014-06-06T19:14:58.363" Score="11" Body="&lt;p&gt;As long as the vertical tail surface sits above the centerline (more precisely the longitudinal axis of inertia - for now we can assume both fall together), any side force will also create a rolling moment.  This is undesirable because now a yaw command will not only create the intended yawing moment, but also a rolling moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to yaw in order to turn, the vertical tail above the centerline will even roll the aircraft in the wrong direction, so you need more coordinated aileron command than with a symmetrical vertical tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the short answer to your question is: Terry is right: Extending the vertical tail below is clearly a benefit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be seen by the widespread use of ventral fins in combat aircraft. Adding area below the centerline helps to reduce the roll contribution of the vertical tail in a sideslip, which improves handling characteristics (more directional stability AND lower yaw-induced roll). See the picture below for an example where the effects of additional vertical tail area are compared to the effects of a ventral fin of the same area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cinDn.jpg&quot; alt=&quot;comparison of fin and vertical tail area effectiveness&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At supersonic speeds, the low aspect ratio ventral fin has a nearly constant contribution to directional stability, whereas the wing-like vertical tail loses effectivity in proportion to the Prandtl-Glauert factor $\frac{1}{\sqrt{Ma^2-1}}$. The small ventral fin of the F-104 raised directional stability by 30% at Mach 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NHshF.png&quot; alt=&quot;F-104 ventral fin contribution to directional stability&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high angles of attack, the vertical tail is in the wake of the fuselage which reduces local dynamic pressure and, consequently, effectivity. The ventral fin then is in ideal flow conditions, so it can help to stabilize the aircraft at high angle of attack, just when the fuselage contribution to instability is largest.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-19T07:44:35.220" LastActivityDate="2014-06-19T07:44:35.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5243" PostTypeId="1" AcceptedAnswerId="5245" CreationDate="2014-06-06T19:17:06.810" Score="4" ViewCount="983" Body="&lt;p&gt;I was trying to calculate the forces generated by an uncommanded flap deployment during cruising flight ($M_\infty=0.85, Alt.=36kft$) in comparison to the forces say, during landing. Assuming similar geometries, the forces will be proportional to the freestream dynamic pressure. If $q_\infty=\frac{\gamma}{2}p_\infty {M_\infty}^2$, the Mach number will be higher at cruise but the static pressure will be lower due to altitude. Thus, it is not immediately obvious to me which flight condition has the higher dynamic pressure. Does anyone have reasonable numbers for $q_\infty [lbf/ft^2]$ at landing vs cruise for a modern commercial airliner so that I can compare?&lt;/p&gt;&#xA;" OwnerUserId="2473" LastEditorUserId="2473" LastEditDate="2014-06-06T19:32:09.203" LastActivityDate="2014-06-07T00:25:00.210" Title="Is the freestream dynamic pressure higher during cruise or during landing/takeoff?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5244" PostTypeId="2" ParentId="5243" CreationDate="2014-06-06T19:32:38.810" Score="2" Body="&lt;p&gt;The aircraft needs flaps in order to be slow enough for take-off and landing. This means the lift coefficient $c_l$ is larger in the landing configuration, and the dynamic pressure is proportionally lower, because lift is the product of $c_l$, the wing area and the dynamic pressure. Since the mass of the aircraft is roughly the same at the end of cruise and during landing, this product must be the same in both conditions.&#xA;&lt;P&gt;&#xA;Real-world examples: Double slotted flaps plus slats will give you a $c_{l\,max}$ of maybe 3.2, so your flight $c_l$ is around 2 to have enough safety margin. Cruise $c_l$ for the same airplane would be between 0.3 and 0.4.&#xA;&lt;P&gt;&#xA;Now with your more precise question I can give a more precise answer. Let's say wing loading is 500 $kg/m^2$, then your dynamic pressure in the landing phase will be 2600 $N/m^2$ versus 14000 $N/m^2$ in cruise. I guess this has not been obvious because you were stuck with imperial units. Do it with metric units, and things should be immediately clear. Formula: $$q = \frac{m \cdot g}{S \cdot c_l}$$&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-06T20:38:21.127" LastActivityDate="2014-06-06T20:38:21.127" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="5245" PostTypeId="2" ParentId="5243" CreationDate="2014-06-06T20:00:10.537" Score="4" Body="&lt;p&gt;Here is what I am getting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.engineeringtoolbox.com/air-altitude-density-volume-d_195.html&quot; rel=&quot;nofollow&quot;&gt;Static pressure&lt;/a&gt;&lt;/strong&gt;:&lt;br&gt;&#xA;Sea level: 101300 Pa&lt;br&gt;&#xA;30,000 feet: 30100 Pa&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mach&lt;/strong&gt;:&lt;br&gt;&#xA;Sea level&lt;sup&gt;1&lt;/sup&gt; (150 kt): 0.22&lt;br&gt;&#xA;Cruise&lt;sup&gt;2&lt;/sup&gt;: 0.85&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.grc.nasa.gov/WWW/BGH/stagtmp.html&quot; rel=&quot;nofollow&quot;&gt;Ratio of specific heats&lt;/a&gt;&lt;/strong&gt;: 1.4&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Using the equation&lt;/strong&gt;:&lt;br&gt;&#xA;Landing: $3432.044 Pa = 73.68 lbf/ft^2$&lt;br&gt;&#xA;Cruise: $15223.075 Pa = 317.94 lbf/ft^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the high Mach in cruise more than compensates for the lower static pressure. &lt;a href=&quot;http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/atmos/stdatm.html&quot; rel=&quot;nofollow&quot;&gt;This calculator&lt;/a&gt; agrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;Landing speeds for large jets are generally between 120-150 knots (Mach 0.18-0.22). Smaller planes around 60 knots (Mach 0.091). You can convert to Mach &lt;a href=&quot;http://en.wikipedia.org/wiki/Mach_number#Calculation&quot; rel=&quot;nofollow&quot;&gt;by hand&lt;/a&gt; or using a calculator like &lt;a href=&quot;http://www.hochwarth.com/misc/AviationCalculator.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;Cruise speeds are generally between 240-280 kias (knots indicated airspeed) for large jets, which translates to around 450-500 knots ground speed and Mach 0.75-0.85 (depending on altitude and conditions).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-07T00:25:00.210" LastActivityDate="2014-06-07T00:25:00.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5246" PostTypeId="1" CreationDate="2014-06-06T21:10:37.437" Score="10" ViewCount="7400" Body="&lt;p&gt;Pigeons are annoying since they make aggressive cooing noises near my house. Considering many options for their dispersal, it seems lasers are one options since for some reason the lasers drive the pigeons crazy. In one video pigeons are completely dispersed by a 150mw green laser, making it appear to be an attractive option for dispersing my pigeon problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However I am concerned that maybe the lasers will continue into the atmosphere past the pigeons, and will affect air traffic....Obviously this is not worth the benefit of dispersing pigeons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this totally out of the question? Are there any rules of thumb one should follow here to be on the safe side to not affect aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2562" LastEditorUserId="97" LastEditDate="2014-12-20T00:38:25.193" LastActivityDate="2014-12-20T10:35:43.350" Title="Can I use a 150mw green laser to scare pigeons and not interfere with air traffic?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;laser-illumination&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="5247" PostTypeId="2" ParentId="5246" CreationDate="2014-06-06T21:51:15.073" Score="18" Body="&lt;p&gt;There are cases where you can use a laser pointer safely, such as pointing out constellations in a dark field far from any air traffic, but as a general rule of thumb lasers should not be pointed skyward - not even to get rid of &lt;s&gt;irritating sky rats&lt;/s&gt; pigeons.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should you wind up illuminating an aircraft with your laser &lt;a href=&quot;https://aviation.stackexchange.com/questions/2817/why-is-laser-illumation-of-a-cockpit-an-emergency&quot;&gt;you can cause serious problems for the crew&lt;/a&gt; - inadvertent or not it could get you a visit from some very unhappy law enforcement officials.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wikihow.com/Get-Rid-of-Pigeons&quot; rel=&quot;nofollow noreferrer&quot;&gt;There are many other ways to get rid of pigeons&lt;/a&gt;, some of which are used at airports and many of which are more effective (and safer) than your laser idea.&lt;br&gt;&#xA;Your local Animal Control group may be able to offer some additional ideas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Avoid the &quot;predator bird statue&quot; idea - in my experience pigeons realize it's fake and use it as a toilet.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-06-06T21:51:15.073" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5248" PostTypeId="2" ParentId="5239" CreationDate="2014-06-07T00:06:10.677" Score="2" Body="&lt;p&gt;Not to suggest this as an answer but as a minor factor that may be a consideration. When the vertical stab is above the aircraft's center of gravity, its drag causes a slight pitch up force assisting the elevator in supplying the pitch up force needed to counter the typical pitch down tendency due to the center of gravity being just forward of the wing's center of lift. If you put half of the vertical stab below the aircraft's CG, you will cancel this small benefit and cause the elevator to do all the compensating itself thus adding extra (albeit a small amount of) drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drag vector of a horizontal stab in a tee tail configuration offers a bit of help in this regard too and if you placed half the vertical below the centerline on a tee tail aircraft, the lowered horizontal's drag vector arm would reduce the pitch up force supplied by its drag and you would get a slight overall drag increase from the elevator's extra load.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2014-06-07T00:06:10.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="5249" PostTypeId="2" ParentId="5246" CreationDate="2014-06-07T06:26:41.460" Score="10" Body="&lt;p&gt;I use a marshmallow gun to scare away squirrels and grackles from my bird feeder. The mini marshmallows are biodegradable (and yummy) and the gun's pop when it shoots is enough to get the critters running. In the uncommon event of actually hitting them, no permanent damage is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And in response to your question, I think you might end up blinding the pigeons and building up bad pigeon karma. &lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="1961" LastEditDate="2014-06-07T16:53:28.583" LastActivityDate="2014-06-07T16:53:28.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="5250" PostTypeId="1" CreationDate="2014-06-07T16:32:38.127" Score="10" ViewCount="7478" Body="&lt;p&gt;For making videos it would be nice to have some more sound than the engine sound recorded by my GoPro. What ideas do you have to record the aircraft intercom? It won't be a problem for me to have two files (an audio and a video file).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I'm looking for a good sound quality comparable with that which you will have while sitting in the aircraft listening to the intercom.&lt;/p&gt;&#xA;" OwnerUserId="343" LastEditorUserId="19" LastEditDate="2017-09-04T11:45:32.433" LastActivityDate="2018-11-06T22:26:59.117" Title="How to record Intercom / ATC in a small aircraft like a Piper Archer?" Tags="&lt;radio&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5251" PostTypeId="2" ParentId="5250" CreationDate="2014-06-07T17:39:16.613" Score="-3" Body="&lt;p&gt;Find a small microphone or even an earbud speaker that will plug into your recorder's IN jack.  (The earbud will in most cases work like a microphone).  Then just wear it inside the earcup on your headset.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-06-07T17:39:16.613" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="5252" PostTypeId="1" AcceptedAnswerId="5253" CreationDate="2014-06-07T18:27:55.877" Score="6" ViewCount="1901" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.afspc.af.mil/news1/story.asp?id=123412412&quot;&gt;this&lt;/a&gt; article on afspc.af.mil, the first officer of the 737 the pilot in the story was flying with had never taxied a 737. Is this normal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exact quote in the article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After landing, the first officer turned to Gongol and asked if he knew&#xA;  where to taxi, she had never been to the Omaha airport before. Taken&#xA;  aback by how cool, calm and collected the first officer had acted&#xA;  without knowing the airport, Gongol remembered landing at the airport&#xA;  before pilot training.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Surprisingly, taxiing was the most stressful part of the day for the&#xA;  first officer,&quot; said Gongol. &quot;She had never taxied a 737 before and&#xA;  the ATC had no idea that the pilot was the reason for the emergency.&#xA;  We had to make a quick decision that her switching to the pilot's seat&#xA;  and taxiing the aircraft without the training was necessary to save&#xA;  the captain's life.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="718" LastEditorUserId="609" LastEditDate="2014-06-07T18:39:30.717" LastActivityDate="2014-06-08T21:25:27.967" Title="Is it usual for a first officer not to know how to taxi?" Tags="&lt;flight-training&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="5253" PostTypeId="2" ParentId="5252" CreationDate="2014-06-08T01:40:24.437" Score="18" Body="&lt;p&gt;After reading that article carefully, here's what appeared to have happened:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilot collapses&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passenger-with-pilots-license comes to flight deck (with both elitist and sexist chip on his shoulder)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;First officer moves to left seat, PwPL takes right seat, runs the radios and checklists, maybe drops the gear.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;First Officer is a right-seat qualification, on 737s (and many others) the steering handle is on the left side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's quite possible that the FO has never steered a 737 on the ground. It's quite IMpossible that the FO has never taxied an aircraft of any kind before. And there's a huge difference between driving a Gulfstream around and driving a 130-passenger jet around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't take a corner just right, the main gear ends up in the ditch, the wing hits the ground, the engine inhales grass, gravel and maybe the taxiway sign and a couple of gophers. Trashing a Ferrari is cheaper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FO moving to the left seat and flying the plane was the correct action - the B-1 pilot was no more qualified to fly a 737 than I am. But radios are radios, and even the greenest flight attendant can read a checklist. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-06-08T21:25:27.967" LastActivityDate="2014-06-08T21:25:27.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5254" PostTypeId="2" ParentId="5250" CreationDate="2014-06-08T04:23:44.280" Score="8" Body="&lt;p&gt;For the GoPro specifically there are &lt;a href=&quot;http://www.crazedpilot.com/record-aircraft-atc-audio-to-your-gopro-hero-3-camera-hero3-and-gopro3-to-your-intercom/&quot; rel=&quot;nofollow noreferrer&quot;&gt;audio recording cables you can buy&lt;/a&gt; which connect to your intercom jack and provide a pass-thru connection for your headset.&lt;br&gt;&#xA;There are other cable options available to support recording on different devices (e.g. iPhone/Android phones and tablets).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As is often the case with &quot;aviation&quot; accessories these can be somewhat expensive, but they're also pretty reliable drop-in solutions. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5250/how-to-record-intercom-atc-in-a-smal-aircraft-like-a-piper-archer/5254#comment10862_5250&quot;&gt;As mah noted&lt;/a&gt; if you have a spare headset jack you're not using plugging into that can be much cheaper and just as effective.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-06-08T04:23:44.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="5255" PostTypeId="1" AcceptedAnswerId="5256" CreationDate="2014-06-08T13:56:58.767" Score="23" ViewCount="2293" Body="&lt;p&gt;I've taken a few hours towards my private pilot's license and each time we land I've smelled this plume of engine exhaust that we seem to fly/roll through just as we're touching down.  I must be sensitive to the fumes because I usually end up with a slight headache after a few minutes.  I haven't asked my instructor yet (because he may think I'm nuts) but is there any way to avoid this short of holding my breath?  I'm flying in a Cessna 152 for my training.&lt;/p&gt;&#xA;" OwnerUserId="2565" LastEditorUserId="19" LastEditDate="2016-10-14T13:37:13.807" LastActivityDate="2016-10-14T13:37:13.807" Title="Is there a way to avoid exhaust fumes when landing?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="5256" PostTypeId="2" ParentId="5255" CreationDate="2014-06-08T14:05:24.123" Score="42" Body="&lt;p&gt;Smelling exhaust in the cockpit is not normal.  Tell your instructor and squawk the problem.  Bonus - turn it into a learning experience by arranging to be with the A&amp;amp;P when he decowls and inspects.  You can learn a lot about the engine that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are getting a headache from this you may have mild CO poisoning.  This does need to be checked out.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-06-08T14:05:24.123" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6255" PostTypeId="2" ParentId="5255" CreationDate="2014-06-09T09:16:56.490" Score="-6" Body="&lt;p&gt;Dear Aspiring Pilot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By all means; you have stumbled onto the most important issue of being a PIC [Pilot in Command]. You only let that happen ONCE without fully understanding&#xA;why it is happening. There are no little issues as a PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of your pre-flight check walk around should have included pushing down on the 'nose' of the Cessna and check the condition of the shock on the nose-wheel.&#xA;I.E. leaks in hydraulic shaft, tire condition, [nails,glass?]. It also seems when you were checking the wing tanks for water and checking engine oil you would have seen a black 'smudge where the exhaust was leaking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is imperative that  walk around is done; It can point out little things like the fact that a '152' DOES NOT have retractable landing gear;&lt;/p&gt;&#xA;" OwnerUserId="2567" LastActivityDate="2014-06-09T09:16:56.490" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6256" PostTypeId="1" AcceptedAnswerId="6258" CreationDate="2014-06-09T14:24:12.023" Score="10" ViewCount="2955" Body="&lt;p&gt;You're flying along at cruise in say a 737 or similar twin-engined yet. Suddenly, one of your engines shut down for no apparent reason. (or no abnormal indications such as low oil or similar)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Attempt a restart&lt;/strong&gt; and either divert or continue?&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Divert and leave it off&lt;/strong&gt; for an emergency landing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-06-09T14:49:01.307" LastActivityDate="2014-06-10T02:30:08.927" Title="Do airline SOP normally recommend an in-flight engine restart in the case of an unexplained shutdown?" Tags="&lt;safety&gt;&lt;engine-failure&gt;&lt;sop&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6257" PostTypeId="1" AcceptedAnswerId="6261" CreationDate="2014-06-09T14:48:28.357" Score="10" ViewCount="4233" Body="&lt;p&gt;&lt;strong&gt;I just &lt;a href=&quot;https://www.youtube.com/watch?v=NoFDHYIXgBM&quot;&gt;saw this video&lt;/a&gt; on YouTube where a guy flies his plane into Air Force One's temporary flight restriction.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's very clear that ATC are not amused and that he's caused a good deal of trouble. What would likely happen: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To his license? (lose it?)&lt;/li&gt;&#xA;&lt;li&gt;Would he be fined?&lt;/li&gt;&#xA;&lt;li&gt;Would he be arrested?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="64" LastEditDate="2014-06-09T16:15:09.310" LastActivityDate="2014-06-09T20:00:30.020" Title="What would be the likely repercussions of flying into the Air Force One temporary flight restriction area?" Tags="&lt;faa-regulations&gt;&lt;tfr&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6258" PostTypeId="2" ParentId="6256" CreationDate="2014-06-09T14:55:42.973" Score="11" Body="&lt;p&gt;According to item 6-14 in the &lt;a href=&quot;http://trihappy.tistory.com/attachment/hk1.pdf&quot;&gt;737NG Abnormal Procedures Handbook&lt;/a&gt;, you're basically supposed to make sure that the engine is shut down completely and then divert to the nearest suitable airport.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;From The 737NG Abnormal Procedures Handbook&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ENGINE FAILURE/SHUTDOWN&lt;br&gt;&#xA;  Condition: Loss of all thrust on an engine accompanied by illumination of the ENG FAIL  alert or abnormal engine&#xA;  indications&lt;br&gt;&#xA;  Accomplish an engine shutdown only when flight&#xA;  conditions permit.&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;AUTOTHROTTLE (if engaged): DISENGAGE &lt;/li&gt;&#xA;  &lt;li&gt;THRUST LEVER (affected engine): IDLE &lt;/li&gt;&#xA;  &lt;li&gt;ENGINE START LEVER: CUTOFF &lt;/li&gt;&#xA;  &lt;li&gt;APU (if available): START &amp;amp; ON &lt;/li&gt;&#xA;  &lt;li&gt;BUS PACK SWITCH (affected side): OFF &lt;/li&gt;&#xA;  &lt;li&gt;FUEL: BALANCE &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;If wing anti-ice is required:&lt;br&gt;&#xA;  - ISOLATION VALVE SWITCH: AUTO &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Plan to land at&#xA;  the nearest suitable airport.  ACCOMPLISH ONE ENGINE INOPERATIVE&#xA;  LANDING CHECKLIST (BELOW)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, if we're going by the book, I think that diverting would be SOP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, I've read of several examples (like &lt;a href=&quot;http://en.wikipedia.org/wiki/TACA_Flight_110&quot;&gt;TACA Flight 110&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Kegworth_air_disaster&quot;&gt;Flight BD 092&lt;/a&gt;) where the crew tried their best to restart the engine when one or both of the engines flamed out.  So, while the book suggests just shutting the engine down and working on diverting, it seems the common practice is to work on diverting while also trying to start the engine again.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-06-09T17:54:27.913" LastActivityDate="2014-06-09T17:54:27.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6259" PostTypeId="2" ParentId="6256" CreationDate="2014-06-09T15:57:34.787" Score="16" Body="&lt;p&gt;Your question mentions the 737 or similar. If you want answers limited to 2-engine jets, let me know and I'll remove this answer as it is for the 747-100 or -200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether to restart or not depends on the nature of the failure. If there appears to be no problem to do otherwise, a restart would be in order. The checklist for an inflight start from the last airline I flew for (now out of business) is below. The code to the right of each action is who performs it: C - captain, FE - flight engineer, All - all 3 crew members.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Thurst Lever ............................... CLOSE        C&#xA;&#xA;Start Lever ................................ CUTOFF       C&#xA;&#xA;Fuel Pressure .............................. AVAILABLE    FE&#xA;&#xA;Bleed Air Valve ............................ OPEN         FE&#xA;&#xA;Engine Ignition (Sys 1 and Sys 2)&#xA;&#xA;     Above 250 KTS ......................... FLT START    FE&#xA;&#xA;     250 KTS and Below ..................... GND START    FE&#xA;&#xA;Start Lever ................................ RICH/IDLE    C&#xA;&#xA;Engine Instruments ......................... STABILIZED   ALL&#xA;&#xA;Start Lever ................................ IDLE         C&#xA;&#xA;Engine Ignition ............................ AS REQUIRED  FE&#xA;&#xA;Electrical Power ........................... RESTORE      FE&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The most likely cause for a Pratt &amp;amp; Whitney JT-9 engine to quit is poor technique on the part of the pilot. If you're at altitude and starting the initial descent, you should put the nose down before bringing the thrust levers back. Also, don't slam them back, take a few seconds to do it, especially if you're above FL370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth noting that on the 747, the loss of an engine (no restart) enroute is not considered a serious emergency. At the two 747 carriers I flew for, it was the captain's discretion as to whether to divert or to continue on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it's not always the case of either the engine works at the power of the other engines or it doesn't. There are situations where the engine might be available, but with partial power. As I remember there were at least two such cases, one of which was high oil temperature. Basically the work-around was to run the engine at that power setting that would keep the oil temp below the maximum.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-06-10T02:30:08.927" LastActivityDate="2014-06-10T02:30:08.927" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6260" PostTypeId="2" ParentId="6257" CreationDate="2014-06-09T18:34:55.330" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.seattlepi.com/local/article/Fighters-scrambled-after-flight-restriction-890871.php&quot; rel=&quot;nofollow&quot;&gt;This news article&lt;/a&gt; describes a real incident that happened in Seattle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if he was punished much beyond some remedial training and a black mark on his record.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-06-09T18:34:55.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6261" PostTypeId="2" ParentId="6257" CreationDate="2014-06-09T20:00:30.020" Score="8" Body="&lt;p&gt;The answer to each of the points in your question is &quot;Maybe&quot;.&lt;br&gt;&#xA;A pilot wandering into a presidential TFR (and many other &quot;VIP Movement&quot; TFRs) potentially faces some pretty severe consequences. Quoting the standard language from one such TFR NOTAM:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;THE FEDERAL AVIATION ADMINISTRATION (FAA) CLASSIFIES THE AIRSPACE DEFINED IN THIS NOTAM AS 'NATIONAL DEFENSE AIRSPACE'. PILOTS WHO DO NOT ADHERE TO THE FOLLOWING PROCEDURES MAY BE INTERCEPTED, DETAINED AND INTERVIEWED BY LAW ENFORCEMENT / SECURITY PERSONNEL.&lt;br&gt;&#xA;   ANY OF THE FOLLOWING ADDITIONAL ACTIONS MAY ALSO BE TAKEN AGAINST A PILOT WHO DOES NOT COMPLY WITH THE REQUIREMENTS OR ANY SPECIAL INSTRUCTIONS OR PROCEDURES ANNOUNCED IN THIS NOTAM:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A) THE FAA MAY TAKE ADMINISTRATIVE ACTION, INCLUDING IMPOSING CIVIL PENALTIES AND THE SUSPENSION OR REVOCATION OF AIRMEN CERTIFICATES; OR  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;B) THE UNITED STATES GOVERNMENT MAY PURSUE CRIMINAL CHARGES, INCLUDING CHARGES UNDER TITLE 49 OF THE UNITED STATES CODE, SECTION 46307; OR  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;C) THE UNITED STATES GOVERNMENT MAY USE DEADLY FORCE AGAINST THE AIRBORNE AIRCRAFT, IF IT IS DETERMINED THAT THE AIRCRAFT POSES AN IMMINENT SECURITY THREAT.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That's a lot of &lt;b&gt;MAY&lt;/b&gt;s, so what does it mean in practice?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The pilot &lt;em&gt;will&lt;/em&gt; be detained and interviewed by law enforcement&lt;/strong&gt;&lt;br&gt;&#xA;May is a nice word, but in practice if a pilot flies into one of these TFRs they &lt;em&gt;will&lt;/em&gt; be held and questioned once they're on the ground to find out why it happened. It's kind of a big deal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The pilot &lt;em&gt;will&lt;/em&gt; face some kind of Administrative Action from the FAA&lt;/strong&gt;&lt;br&gt;&#xA;Suspension or revocation of their certificate is certainly possible (especially if it's not the first time).&lt;br&gt;&#xA;A stern talking-to from someone at the FSDO and/or a &lt;a href=&quot;http://www.gpo.gov/fdsys/granule/USCODE-2011-title49/USCODE-2011-title49-subtitleVII-partA-subpartiii-chap447-sec44709&quot;&gt;reexamination (&quot;709 ride&quot;)&lt;/a&gt; is almost certain.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The pilot may face Civil Penalties (a nice way of saying &quot;fines&quot;)&lt;/strong&gt;&lt;br&gt;&#xA;$10,000 used to be the magic number for these fines as defined in 49USC, the law now refers back to 18USC (which I'm not going to read through because reading the US Code makes my head hurt), but I assume it hasn't gone down. The point is it could be an expensive error.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The pilot may face Criminal Charges (arrest and imprisonment)&lt;/strong&gt;&lt;br&gt;&#xA;I can't recall a case of a pilot &lt;em&gt;accidentally&lt;/em&gt; violating a TFR and being locked up for it, but I imagine &lt;em&gt;willfully&lt;/em&gt; violating a TFR could land you in prison pretty easily.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Use of deadly force may occur (the pilot may be shot down)&lt;/strong&gt;&lt;br&gt;&#xA;Again, I can't recall a case where a pilot has violated a TFR and been blown out of the sky by a missile from an F-16 (though there are plenty of cases where aircraft have been intercepted and diverted), but it is an option available if the aircraft poses an &quot;imminent security threat&quot;, however that determination is made.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-09T20:00:30.020" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6262" PostTypeId="1" CreationDate="2014-06-10T03:18:20.913" Score="7" ViewCount="480" Body="&lt;p&gt;Looking at the NDB RWY 15 into Fort Hood/Killeen, why is the procedural track from OKEST showing a heading of 151 degrees when the final approach course heading is 150 degrees. Is that simply a typo? The best answer I can come up is that from OKEST to the LOM is 6.3NM on a heading of 151 degrees. Is the 151 heading to GRK VOR or to the LOM using the NDB? Any thoughts?&lt;img src=&quot;https://i.stack.imgur.com/uBIDh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2571" LastEditorUserId="572" LastEditDate="2015-02-19T09:27:17.617" LastActivityDate="2015-02-19T09:27:17.617" Title="Why is there a difference between the procedural track heading and final approach course at Fort Hood (KGRK)?" Tags="&lt;non-precision-approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6263" PostTypeId="1" AcceptedAnswerId="6273" CreationDate="2014-06-10T05:05:59.857" Score="20" ViewCount="16325" Body="&lt;p&gt;Just out of vague curiosity, what aircraft has the highest recommended landing speed for an earth bound (atmospheric) craft?  And, btw, when I say &quot;landing&quot; I define it as thus:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Controlled&lt;/li&gt;&#xA;&lt;li&gt;Powered (though if you want to note unpowered, feel free)&lt;/li&gt;&#xA;&lt;li&gt;Safe, with the vehicle/aircraft fully recoverable&lt;/li&gt;&#xA;&lt;li&gt;On a runway&lt;/li&gt;&#xA;&lt;li&gt;On wheels or skids&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I know there may be multiple answers, even with my trying to narrow it down, so feel free to list a few different scenarios.  I'm mostly wondering about planes that are in common usage though, both military and civilian (past and present)...  I'd have to think something like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot;&gt;SR-71&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25&quot;&gt;MIG-25&lt;/a&gt; would be very close to the top of the list, if not the top.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-06-10T17:59:39.093" LastActivityDate="2018-01-27T12:39:34.447" Title="What aircraft has the highest suggested landing speed?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;" AnswerCount="5" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="6264" PostTypeId="2" ParentId="6263" CreationDate="2014-06-10T06:26:09.997" Score="3" Body="&lt;p&gt;Concorde's landing speed was &lt;a href=&quot;http://www.britishairways.com/en-au/information/about-ba/history-and-heritage/celebrating-concorde&quot; rel=&quot;nofollow noreferrer&quot;&gt;300 km/h&lt;/a&gt;. Its high speed was due to its small wings, designed for supercruise, which required higher airspeeds to maintain lift during the approach. Possibly the XB-70 Valkyrie, being also a large supersonic aircraft, would have had higher landing speeds, but I can't find a reference for its landing speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Space Shuttle regularly &lt;a href=&quot;http://www.nasa.gov/centers/johnson/pdf/390651main_shuttle_crew_operations_manual.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;landed at 350-400 km/h&lt;/a&gt; under control, though without power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1IsAQ.png&quot; alt=&quot;Image from NASA link&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="558" LastEditDate="2014-06-11T05:28:27.393" LastActivityDate="2014-06-11T05:28:27.393" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="6265" PostTypeId="1" CreationDate="2014-06-10T14:17:23.000" Score="2" ViewCount="847" Body="&lt;p&gt;I photographed a couple of aircraft and tried to identify them, but I'm not sure if it's correct. For me, all of them look like an Airbus A320, but I'm really unsure. So which of these aircraft is an Airbus A320 and if not, what's the correct type?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2N6SI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/xOP0u.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/1Dmqq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/FiRTv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2210" LastActivityDate="2014-06-10T16:28:15.647" Title="Did I identify these aircraft correctly?" Tags="&lt;plane-spotting&gt;&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6266" PostTypeId="2" ParentId="6265" CreationDate="2014-06-10T14:26:48.697" Score="7" Body="&lt;p&gt;Looks like it :) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Double window exits over the wings, so no A321 or A319 (with a few exceptions such as Easyjet's A319)&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-06-10T14:26:48.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6267" PostTypeId="2" ParentId="6262" CreationDate="2014-06-10T15:15:13.717" Score="5" Body="&lt;p&gt;It's really only confusing because they are within one degree of each other, but this actually happens quite a bit with feeder routes.&lt;/p&gt;&#xA;&lt;h3&gt;The 151 Degree Course NW of STARN&lt;/h3&gt;&#xA;&lt;p&gt;The 151 degree course (and the OKEST intersection) is only used if you are using AGJ as the Initial Approach Fix (IAF). This is the course that you would fly from OKEST towards the GRK VOR (on the GRK 331 degree radial) in order to get to STARN.  After reaching STARN, you would fly the 150 degree bearing outbound from STARN and the rest of the approach using STARN to navigate.&lt;/p&gt;&#xA;&lt;h3&gt;The 150 Degree Bearing NW of STARN&lt;/h3&gt;&#xA;&lt;p&gt;If you were to use STARN as the IAF instead of AGJ, you would fly the procedure turn on the 150 degree bearing from it in order to get yourself established on the correct inbound course to fly the rest of the approach.  In this case, you would never use GRK at all.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-06-10T15:15:13.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6268" PostTypeId="2" ParentId="6265" CreationDate="2014-06-10T15:27:40.973" Score="4" Body="&lt;p&gt;All correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you look at the engines, you'll see that the British Airways A320 is equipped with different engines than the other three. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Swiss and NIKI aircraft are A320-214 and use the CFM56 series engine build by CFM international.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The BA aircraft is an A320-232 and it has the IAE V2500 series engine build by International Aero Engines. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-06-10T16:28:15.647" LastActivityDate="2014-06-10T16:28:15.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6269" PostTypeId="2" ParentId="5250" CreationDate="2014-06-10T17:39:18.470" Score="3" Body="&lt;p&gt;The specialized aviation adapter cables are fantastically overpriced (there must be a law somewhere that companies are required to rip-off aviation consumers). Assuming you have an open headset port on your intercom, save yourself a few bucks and just buy a 1/8 to 1/4 TRS cable. You can get it on &lt;a href=&quot;http://amzn.com/B000068O36&quot; rel=&quot;nofollow noreferrer&quot;&gt;Amazon&lt;/a&gt; for less than $7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, if you have the Hero 3, you're still stuck getting a USB audio input adapter (you would need this for any type of external audio input anyway). But even then you're only out 17 bucks, versus spending $44 (!) for a specialized cable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the high signal output, this doesn't appear to be a problem with the GoPros; I've successfully recorded a bunch of flights this way with no issue. Besides, as far as I know, none of the specialized cables provide any type of impedance matching either.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2018-11-06T22:26:59.117" LastActivityDate="2018-11-06T22:26:59.117" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="6270" PostTypeId="1" AcceptedAnswerId="6272" CreationDate="2014-06-10T18:27:02.937" Score="18" ViewCount="11193" Body="&lt;p&gt;I've heard this term used &lt;a href=&quot;https://aviation.stackexchange.com/questions/1423/what-vertical-speed-at-touchdown-makes-a-perfect-landing?answertab=votes#tab-top&quot;&gt;a few times&lt;/a&gt; to describe a really smooth landing (one where you hardly feel a bump).  But where does this term actually come from?  I'm not sure how grease (a lubricant) came to symbolize a low g-load on landing?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-12-09T08:22:04.840" Title="Where does the term 'greased landing' come from?" Tags="&lt;landing&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6272" PostTypeId="2" ParentId="6270" CreationDate="2014-06-10T19:56:05.923" Score="15" Body="&lt;p&gt;I've always heard this referred to as a &quot;greased landing&quot; or a &quot;greaser&quot;, but never a &quot;greaser landing&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that it is referring to a landing that was so good that somebody must have greased the entire runway so that you didn't even feel the airplane touch down.  If you've ever tried to pick something up that has been well greased, then you know what they are referring to.  It's very slippery and slides right out of your hands no matter how hard you try.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-06-10T19:56:05.923" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6273" PostTypeId="2" ParentId="6263" CreationDate="2014-06-11T05:59:35.397" Score="15" Body="&lt;p&gt;Based on its fixed-wing hypersonic design and inordinately high wing loading, I would predict that the X-15 has the highest recommend landing speed of any earthbound aircraft, with a preliminary search seemingly bearing this hypothesis out. According to an ostensibly legitimate NASA source (link below), the X-15's normal landing speed was 200+mph (173.8kts=321.9kph),&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-052-DFRC.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-052-DFRC.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if unofficial sources are to be believed, its actual landing speed was much higher, closer to 390kph=208kts (although these numbers are admittedly more dubious):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“According to an early edition of 'the Guinness book of world records' the X15 also holds the record for fastest landing speed at 242 mph compared with 210 mph for the space shuttle.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://area51specialprojects.com/x15.html&quot; rel=&quot;noreferrer&quot;&gt;http://area51specialprojects.com/x15.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If only powered aircraft are open to consideration, then the F-104 Starfighter would have to be up there as well. It needed a blown-flap flow control system just to be sane during landing...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“To make landing speeds “reasonable,” The F-104 forced engine air through the wings to smooth the airflow and give more lift. With bleed air, the Zipper could land at the challenging but not extreme speed of 160 to 165 knots. If the air-bleed system was not working, landing speeds climbed to 240 knots.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.pacificaviationmuseum.org/pearl-harbor-blog/lockheed-f-104-starfighter&quot; rel=&quot;noreferrer&quot;&gt;http://www.pacificaviationmuseum.org/pearl-harbor-blog/lockheed-f-104-starfighter&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if mechanical failure scenarios are deemed admissible, then the F-104 without its crucial boundary layer control systems would be the clear winner for powered landing speed, weighing in at an absolutely terrifying 240 kts. Otherwise, it would appear that the X-15 (unofficially) reigns supreme.&lt;/p&gt;&#xA;" OwnerUserId="2473" LastEditorUserId="14897" LastEditDate="2018-01-24T15:56:57.607" LastActivityDate="2018-01-24T15:56:57.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6274" PostTypeId="2" ParentId="6263" CreationDate="2014-06-11T10:59:49.950" Score="6" Body="&lt;p&gt;More high speed lawndarts:&lt;br/&gt;&#xA;Presenting the F-102A Delta Dagger.&#xA;&lt;br/&gt;&#xA;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/1430310464&quot;&gt;http://www.amazon.com/Convair-Dagger-Pilots-Flight-Operating/dp/1430310464&lt;/a&gt; lists final approach speeds as high as 185 KIAS, with touchdown speed of 145 KIAS for the same fuel load.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And the B-58 Hustler&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.aviation-history.com/convair/b58.html&quot;&gt;http://www.aviation-history.com/convair/b58.html&lt;/a&gt; says it had a touchdown speed of 165 KIAS. Which would lead to an approach speed even higher than that of the F-102.&lt;br/&gt;&#xA;&lt;a href=&quot;http://wikimapia.org/7029449/Important-B-58-landing-approach-aid&quot;&gt;http://wikimapia.org/7029449/Important-B-58-landing-approach-aid&lt;/a&gt; says it landed at &quot;just under 200 knots&quot;, even higher then unless they mean approach speed rather than touchdown speed.&lt;br/&gt;&lt;br/&gt;&#xA;The XB-70&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/87774main_H-587.pdf&quot;&gt;http://www.nasa.gov/centers/dryden/pdf/87774main_H-587.pdf&lt;/a&gt; mentions an approach speed of 200-210KIAS, with touchdown at 175-185KIAS.&lt;br/&gt;&#xA;And that for a lightly loaded prototype, the production machines would have been heavier...&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So that may well be the top candidate for the job (excluding non-normal operations), if we exclude the X-15 and Space Shuttle which were gliders during their landing phase.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-06-11T10:59:49.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6275" PostTypeId="1" AcceptedAnswerId="6278" CreationDate="2014-06-11T11:05:50.837" Score="15" ViewCount="9212" Body="&lt;p&gt;It's widely known that to perform a coordinated turn, rudder must be turned as well as ailerons. My question is what to do after the desired bank angle is achieved?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/FAA-H-8083-3B.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airplane Flying Handbook&lt;/a&gt; we read:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After the bank has been established in a medium&#xA;  banked turn, all pressure applied to the aileron may be&#xA;  relaxed. The airplane will remain at the selected bank&#xA;  with no further tendency to yaw since there is no&#xA;  longer a deflection of the ailerons. As a result, pres-&#xA;  sure may also be relaxed on the rudder pedals, and the&#xA;  rudder allowed to streamline itself with the direction&#xA;  of the slipstream.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So does that mean that the pedals will remain in &quot;shifted&quot; position as a result of the rudder remaining slightly turned?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also wonder how this is imitated in simulators (I'm using FlightGear) as all (even expensive) simulator pedals return to &quot;zero&quot; position themselves?&lt;/p&gt;&#xA;" OwnerUserId="2581" LastEditorUserId="1696" LastEditDate="2015-02-23T01:50:26.677" LastActivityDate="2019-07-29T21:16:08.040" Title="Does the rudder need to be held throughout a coordinated turn?" Tags="&lt;flight-controls&gt;&lt;ailerons&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6276" PostTypeId="1" AcceptedAnswerId="6279" CreationDate="2014-06-11T11:09:13.673" Score="10" ViewCount="1741" Body="&lt;p&gt;In a previous &lt;a href=&quot;https://aviation.stackexchange.com/questions/786/is-it-even-remotely-feasible-to-turnback-a-single-engine-aircraft-with-an-engine&quot;&gt;question&lt;/a&gt; the case about if a turnback would be feasible, specifically for a single engine aircraft, has been analysed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But given a &lt;em&gt;twin-engine&lt;/em&gt; general aviation aircraft and a &lt;em&gt;single&lt;/em&gt; engine failure immediately after lift-off, considering that my Pilot handbook says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A continued take-off is not recommended if the steady rate of climb according to &quot;Section XX&quot; is less than Y%.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Considering the quite dangerous setting, I would say that is quite impractical to go and check that table in such a situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of indicators might I look for to check if it safe to continue? Should I learn by heart such table? (I am not sure this is practical either, is a quite complex table)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case I am unsure what to do, apart from trying to climb for a while then turn around or immediately try land in front of me (granted that there is enough space), are there, generally speaking, other options?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;https://aviation.stackexchange.com/a/857/1467&quot;&gt;accepted answer&lt;/a&gt; of the listed question is said that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It's not reasonable to try it [a turnaround] without knowing what altitude is needed for it at current conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;is it possible to estimate this quickly inside the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-04T16:56:23.557" Title="Single engine failure in a light twin after lift-off: what to do?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;general-aviation&gt;&lt;multi-engine&gt;&lt;engine-failure&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6277" PostTypeId="2" ParentId="6276" CreationDate="2014-06-11T11:22:05.810" Score="5" Body="&lt;p&gt;After you've learned your airplane and its characteristics, you will know if something is not right. The decision to land, when that's something that can be safely done, is never the wrong one if you're not comfortable with your performance and problems can be checked out on the ground with nobody dying usually!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding a safe altitude to turn around in... you need to know your aircraft to answer this, but it's not terribly difficult to learn. You can fly to a few thousand feet AGL (preferably with a CFI or other capable safety pilot), fly at whatever speed you climb at, pull your throttle out and see how much altitude you lose while doing a 180 degree turn (simulating turning back to your departure runway). Try this under different conditions (max gross weight vs. generally empty; high density altitude vs low for example) to learn how these factors affect your altitude loss. Then apply a safety margin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been taught that a general figure (without recognition of the specific aircraft or conditions) is 500 feet. This is &lt;em&gt;not&lt;/em&gt; to say a turn-around is safe at 500 feet! It's just a baseline of consideration. Other factors are going to include how much runway you're going to have if you're able to turn around!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of my primary instructors, before every first launch of the day, had me go through an aborted landing briefing similar to: if we have an emergency below 500 feet we're going to land straight ahead. Below 700 feet, we're going to turn to the (left/right) and land on the crossing runway (my airport had 9/27 and 5/23). Higher and we will turn left/right and land on the parallel runway (9/27 R/L; easier to get to than a full 180 in-place).&lt;/p&gt;&#xA;" OwnerUserId="73" LastActivityDate="2014-06-11T11:22:05.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6278" PostTypeId="2" ParentId="6275" CreationDate="2014-06-11T12:41:37.827" Score="15" Body="&lt;p&gt;When you deflect the ailerons, you increase lift on one side of the wing and decrease it on the other. This causes a parallel increase of the local induced drag where lift is increased and vice versa. The consequence of that is a yawing moment which needs to be corrected with rudder deflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once your ailerons are neutral, this yawing moment goes away, but now your airplane is in a constant yawing motion which increases airspeed on the outer wing and swings the tail around, so your vertical tail sees some sideslip even if your ball is centered. The airspeed differential between inner and outer wing causes some friction drag differential which tries to pull the aircraft out of the yawing motion. Depending on the tendency of the rudder to follow a sideslip, you will need some pressure to keep the yawing motion going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard to be more specific, because details depend on the particular airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most of the airplanes I have flown, you also need to keep some aileron deflection to keep your bank angle constant. Here are two effects which go against each other, so again the details depend on the particular aircraft. One effect is caused by the airspeed difference which causes a lift difference between inner and outer wing. To correct this, you need to deflect the aileron against the bank. The other effect is caused by the different centrifugal forces of the masses of the inner and outer wing. The whole wing is moving at the same angular velocity, but centrifugal acceleration is the product of the square of the angular velocity and the radius of your motion. Since the outer wing flies at a larger radius than the inner wing, the masses of the wing will try to pull the aircraft level. This needs aileron deflection into the bank. If you are lucky, both effects cancel each other out, but normally they don't.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-06-11T12:41:37.827" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6279" PostTypeId="2" ParentId="6276" CreationDate="2014-06-11T12:54:34.040" Score="8" Body="&lt;p&gt;What you really should learn by heart is the flight speed for best climb with one engine inoperative. Try to trim that immediately and you will win more time to make a decision. The rest is really depending on circumstances: Is there a landing opportunity ahead? Are you high enough to do a 180 and land on the same runway in opposite direction? Or are you high enough (and the aircraft does not lose altitude) that you can fly a pattern and land normally?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Testing the aircraft at altitude with one engine throttled is highly recommended, but be aware that the remaining thrust / drag of the throttled engine might be different from that of the stopped engine.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-11T18:40:11.037" LastActivityDate="2014-06-11T18:40:11.037" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6280" PostTypeId="1" AcceptedAnswerId="6282" CreationDate="2014-06-11T13:17:15.997" Score="15" ViewCount="10025" Body="&lt;p&gt;When listening to air control traffic, or watching flights on flightradar24.com, some flights show up with ATC call signs (as transmitted on ADS-B) that do not match the flight number as they usually do, some examples:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;TK1880 / THY9QT&#xA;TOM6347 / TOM1FT&#xA;LH1660 / DLH5KK&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;It seems to be more frequent on flight codes that have 4 digits, but this isn't exclusive. Who assigns these call signs, and what is the pattern for the naming?&lt;/p&gt;&#xA;" OwnerUserId="2582" LastEditorUserId="247" LastEditDate="2014-07-01T17:39:54.747" LastActivityDate="2018-06-09T06:34:48.823" Title="Why are some ATC call signs different than the flight number?" Tags="&lt;air-traffic-control&gt;&lt;call-sign&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6282" PostTypeId="2" ParentId="6280" CreationDate="2014-06-11T14:51:00.487" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Who assigns these callsigns, and what is the pattern for the naming?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Callsigns are allocated by ICAO. Their &lt;a href=&quot;http://www.icao.int/safety/acp/.../ACP-WG-C-3/wgc3_wp7.doc&quot; rel=&quot;noreferrer&quot;&gt;Annex 10 Radiotelephony Procedures&lt;/a&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.2.1.7.2    Radiotelephony call signs for aircraft&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1.7.2.1    Full call signs&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1.7.2.1.1    An aircraft radiotelephony call sign shall be one of the following types:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Type a)   —   the characters corresponding to the registration marking of&#xA;  the aircraft; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Type b)   —   the telephony designator of the aircraft operating agency,&#xA;  followed by the last four characters of the registration marking of&#xA;  the aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Type c)   —   the telephony designator of the aircraft operating agency,&#xA;  followed by the flight identification.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note 1.— The name of aircraft manufacturer or name of aircraft model&#xA;  may be used as a radiotelephony prefix to the Type a) call sign above&#xA;  (see Table 5-1).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note 2.— The telephony designators referred to in b) and c) above&#xA;  are contained in ICAO Doc 8585 — Designators for Aircraft Operating&#xA;  Agencies, Aeronautical Authorities and Services.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the case of TOM6347 / TOM1FT,&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Flight Number:         TOM6347 &#xA;Aircraft Registration: G-CPEU&#xA;Aircraft type:         B752&#xA;Callsign:              TOM1FT&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;As Jamiec commented, TOM1FT &lt;em&gt;'matches &quot;C&quot; - 1FT is the carrier-allocated &quot;flight identification&quot;'&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess the use of alphanumeric flight identifications may be due to the 7-character limit on ICAO callsigns, the use of 3-character ICAO prefixes, the use of single-character suffixes (e.g. for delayed flights) and the need by large airlines for more than 1000 flight numbers - &lt;a href=&quot;http://www.icao.int/APAC/Meetings/2011_FPL_AM_TF4_Seminar/WP13.pdf&quot; rel=&quot;noreferrer&quot;&gt;Reference&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight Identifications can be changed when two or more flights with similar flight numbers fly close to each other.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-11T15:09:16.890" LastActivityDate="2014-06-11T15:09:16.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6283" PostTypeId="1" AcceptedAnswerId="6284" CreationDate="2014-06-11T18:46:02.560" Score="17" ViewCount="9163" Body="&lt;p&gt;I plan on owning my own plane in the coming years and using it to get my PPL.  I've recently been turned on to leaseback with flying clubs.  The pros seem to heavily outweigh the cons, but I always wonder.  What are the common (and uncommon) downsides to employing a leaseback with your own airplane?&lt;/p&gt;&#xA;" OwnerUserId="21" LastActivityDate="2020-11-19T02:40:48.820" Title="What are common downsides to leasing an aircraft to a flying club?" Tags="&lt;aircraft-ownership&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6284" PostTypeId="2" ParentId="6283" CreationDate="2014-06-11T19:32:42.927" Score="14" Body="&lt;p&gt;A leaseback can be advantageous, especially when you use the aircraft for your own flight training and travel.  But there are some things you need to watch out for:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Other people will be using your aircraft - whether people admit it or not, nobody will take care of the plane as well as you do. If you think you might take issue with trash in the cockpit, a scratch on the panel, or a tear in the seat, you might want to give this a second thought. In my experience, flying clubs seem to have pilots that take better care of the aircraft, since membership is controlled. &lt;/li&gt;&#xA;&lt;li&gt;You'll have to schedule your flights - just like everyone else (though some concessions are usually made for the owner). The bottom line is, you won't be able to just get up and go fly somewhere at a moment's notice anymore.&lt;/li&gt;&#xA;&lt;li&gt;You have to play by someone else's maintenance rules - While you have to comply with FARs  in any case, the lessee typically will have stipulations that they (or their designee) will perform any required maintenance on your behalf and your say in the matter will be limited. Of course, you still have the honor of paying for any maintenance performed (typically at little or no discount). &lt;/li&gt;&#xA;&lt;li&gt;Your capital is tied up - This can be a good or bad thing. It's good in the sense that aircraft tend to be a good hedge against inflation risk. It's bad because you're precluded from using the money on something else. This is one of the main reasons that flight schools/clubs LOVE leasebacks.&lt;/li&gt;&#xA;&lt;li&gt;If you're looking to make money... it won't happen - most leasebacks only help offset the expense of operating the aircraft. If you're looking for a return on your investment, better to look somewhere else. Do it only to reduce the cost of ownership on something you want anyway.&lt;/li&gt;&#xA;&lt;li&gt;Finally, YOU take on the financial risk of the aircraft - in most leaseback situations, you are reimbursed for any use, but are still responsible for any finance and indirect (and sometimes direct) maintenance costs. These have to be paid, whether the aircraft is flying or not. And if business starts to slow down... well, I'll give you a hint: it's not the flying club that has to pay to keep your plane airworthy.  This is the main other reason flight schools/clubs LOVE leasebacks.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2014-06-11T19:32:42.927" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6285" PostTypeId="1" AcceptedAnswerId="6289" CreationDate="2014-06-12T06:21:01.647" Score="35" ViewCount="32874" Body="&lt;p&gt;What are the rationale behind this &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Dihedral_(aeronautics)#Anhedral&quot; rel=&quot;noreferrer&quot;&gt;anhedral&lt;/a&gt;&lt;/strong&gt; high mounted wing configuration? Is that usual for very large carge aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/soJjK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="22726" LastEditDate="2019-05-18T21:51:44.920" LastActivityDate="2019-05-18T21:51:44.920" Title="Why does An-225 have anhedral wings though it is a cargo aircraft?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;cargo&gt;&lt;antonov-225&gt;" AnswerCount="9" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6287" PostTypeId="2" ParentId="6285" CreationDate="2014-06-12T08:16:43.497" Score="3" Body="&lt;p&gt;It is not unusual for a dedicated cargo plane design to have a high mounted wing design. It allows for the fuselage of the plane to sit lower on the tarmac while maintaining the ground clearance for the engines and wingtips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also makes it easier to allow the cargo door to be opened in flight without compromising the structural integrity because the main strength of the fuselage comes from the spine in the top where the wings and tail attach to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the list of &lt;a href=&quot;http://en.wikipedia.org/wiki/Military_transport_aircraft&quot; rel=&quot;nofollow&quot;&gt;military transport aircraft&lt;/a&gt;, most use the same wing design. The only exceptions are those based on a civilian aircraft.  &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="911" LastEditDate="2014-06-12T20:48:04.387" LastActivityDate="2014-06-12T20:48:04.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6288" PostTypeId="1" CreationDate="2014-06-12T10:34:23.403" Score="2" ViewCount="927" Body="&lt;p&gt;Is CPDLC (Controller–pilot data link communications) mandatory by EASA? I have not heard any update that Airlines are using CPDLC. While talking to some of the pilots I heard that they have been instructed to switch the System due to satellite cost. What is the real scenario?&lt;/p&gt;&#xA;" OwnerUserId="2589" LastEditorUserId="1696" LastEditDate="2015-02-23T16:36:19.740" LastActivityDate="2015-02-23T16:36:19.740" Title="Is implementation of CPDLC mandated by EASA?" Tags="&lt;icao&gt;&lt;easa&gt;&lt;cpdlc&gt;&lt;acars&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6289" PostTypeId="2" ParentId="6285" CreationDate="2014-06-12T12:00:44.307" Score="52" Body="&lt;p&gt;Anhedral wings will induce roll instability and improve roll maneuverability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a large/heavy airplane with a high-wing configuration there is usually excess roll stability, so this type of wings can be pretty common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7980/in-a-slip-or-skid-how-does-one-wing-have-a-higher-angle-of-attack-and-more-lift/7983#7983&quot;&gt;high wing configuration&lt;/a&gt; and wing sweep contribute a &lt;a href=&quot;https://aviation.stackexchange.com/questions/12099/why-do-low-wing-aircraft-have-higher-dihedral-than-high-wing-aircraft/12101#12101&quot;&gt;negative sideslip-induced rolling moment&lt;/a&gt;, and anhedral is necessary to limit this moment. If sideslip causes strong rolling, the aircraft will have a tendency to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12515/could-a-plane-be-constructed-to-be-fly-in-fixed-stick-roll-stable-circles/12526#12526&quot;&gt;dutch roll&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-15T07:46:10.973" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6290" PostTypeId="5" CreationDate="2014-06-12T13:38:29.477" Score="0" Body="&lt;p&gt;The Aircraft Communications Addressing and Reporting System (ACARS) is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. &lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="19" LastEditDate="2014-06-12T15:59:23.040" LastActivityDate="2014-06-12T15:59:23.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6291" PostTypeId="4" CreationDate="2014-06-12T13:38:29.477" Score="0" Body="ACARS is a digital datalink system that uses radio or satellite communications channels." OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-12T15:58:28.380" LastActivityDate="2014-06-12T15:58:28.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6292" PostTypeId="2" ParentId="6285" CreationDate="2014-06-12T14:32:00.297" Score="21" Body="&lt;p&gt;The anhedral is rather exaggerated in the top photo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look for pictures of the Mriya in flight the wings are more-or-less level. On the ground, fully fueled, the wings with 3 engines each are &lt;strong&gt;heavy&lt;/strong&gt; and will bend down a very noticeable amount. The B-52 has a similar issue, to the point where it has outrigger wheels near the end of the wings to keep them from scraping the pavement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zeutu.jpg&quot; alt=&quot;photo showing the B-52 outrigger wheels&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2590" LastEditorUserId="2591" LastEditDate="2014-06-12T16:52:13.543" LastActivityDate="2014-06-12T16:52:13.543" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="6293" PostTypeId="2" ParentId="6285" CreationDate="2014-06-12T16:21:07.187" Score="6" Body="&lt;p&gt;Both the high wing location and sweepback increase roll stability. Too much roll stability not only reduces maneuverability but is likely to lead to Dutch roll, so anhedral is added to compensate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes with high but unswept wings generally have neither anhedral nor dihedral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Here's a discussion of &lt;a href=&quot;http://www.b2streamlines.com/EffectiveDihedral.pdf&quot; rel=&quot;noreferrer&quot;&gt;stability, dihedral and Dutch roll&lt;/a&gt;, albeit in the context of RC gliders. &lt;/p&gt;&#xA;" OwnerUserId="1981" LastEditorUserId="1981" LastEditDate="2014-06-12T17:11:04.410" LastActivityDate="2014-06-12T17:11:04.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6294" PostTypeId="2" ParentId="6285" CreationDate="2014-06-12T18:36:28.730" Score="36" Body="&lt;p&gt;Yes, this is common in heavy cargo haulers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you probably are aware, a dihedral wing configuration provides roll stability. Roll the plane, and it will naturally roll back to level. A center of mass well below the center of lift provides the same effect. Put a lot of weight down below the center of lift, and you'll get the roll-back effect again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While that's nifty, you can get too much of it. Too much stability makes the plane very hard to turn or otherwise control. You can also get a sort of aerodynamic pendulum-like effect called a &quot;Dutch roll&quot; as the &quot;roll back&quot; action over-corrects and causes a swing back the other way, and back and forth with a combination yaw and roll that is surprisingly effective at inducing air-sickness. Putting an anhedrial angle on the wing counteracts the &quot;too-much-stability&quot; problem created by the weight distribution, making the plane easier to control again and reducing unwanted oscillations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not just make the wings lower? That may solve the stability problem, but it would create other problems as well. Just how low would the wings have to be? Would that design affect safety for ground operations or unpaved runways? And what about cargo -- how well does your new design perform in empty versus loaded configurations? How tall would the landing gear have to be to make such a design safe... and how does that affect loading and unloading?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft, even the comically large Airbus A300-600 Super Transport &quot;Beluga&quot;, opt for the low-wing solution, which invariably leads to a dihedral.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2Zx5T.jpg&quot; alt=&quot;A300-600ST&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Airbus A300-600ST - photo credit: &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a380family/&quot; rel=&quot;noreferrer&quot;&gt;Airbus&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in certain cases, the high-wing plus pronounced anhedrial design has won out for some heavy cargo hauling designs, and is particularly popular with military where they may have to operate out of dirt runways and need to get the wings up away from the ground, and where short landing gear is desirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/275EY.jpg&quot; alt=&quot;C5 Galaxy takeoff&quot;&gt;&#xA;&lt;sup&gt;CG Galaxy at takeoff -- Photo Credit: &lt;a href=&quot;http://www.af.mil/News/Photos/tabid/129/igphoto/2000597681/Default.aspx&quot; rel=&quot;noreferrer&quot;&gt;USAF&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2426" LastEditorUserId="2426" LastEditDate="2014-06-14T16:22:56.607" LastActivityDate="2014-06-14T16:22:56.607" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6295" PostTypeId="2" ParentId="6280" CreationDate="2014-06-12T19:51:29.733" Score="3" Body="&lt;p&gt;Differing flight numbers and ATC call signs are to avoid having two flights with similar call signs in the area at the same time.  In theory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, it doesn't really work as well as it does on paper.  Many similar flights are missed and fly together anyway, and the different call signs are confusing in themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We usually brief a different ATC call sign as a threat in our preflight briefing.  Most pilots I've flown with are of the opinion that they cause more problems than they solve.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-06-12T19:51:29.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6296" PostTypeId="2" ParentId="6288" CreationDate="2014-06-12T20:09:19.613" Score="1" Body="&lt;p&gt;according to eurocontrol, &lt;a href=&quot;http://www.eurocontrol.int/services/link-2000-programme&quot; rel=&quot;nofollow&quot;&gt;http://www.eurocontrol.int/services/link-2000-programme&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The LINK 2000+ Programme started in 2001 and is now in the full scale&#xA;  implementation phase governed by the DLS IR which requires:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• All newly delivered aircraft operating above FL285 to be equipped as&#xA;  of 2011,  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Core European ANSPs to be operational by 7 February  2013, &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• The rest of European ANSPs to be operational by 5 February 2015,  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• All existing aircraft operating above FL295 to be retroffited by 5&#xA;  Feb 2015 (unless exempt).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What aircraft are exempt? See page 4 of this pdf: &lt;a href=&quot;http://ec.europa.eu/transport/modes/air/single_european_sky/doc/implementing_rules/2014_01_22_2nd_exemption_under_29_2009.pdf&quot; rel=&quot;nofollow&quot;&gt;http://ec.europa.eu/transport/modes/air/single_european_sky/doc/implementing_rules/2014_01_22_2nd_exemption_under_29_2009.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2014-06-12T20:09:19.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6297" PostTypeId="2" ParentId="475" CreationDate="2014-06-12T20:39:42.920" Score="4" Body="&lt;p&gt;Navy carrier pilots routinely land the same ashore as aboard ship with the exception of the tail hook being stowed ashore (unless you have an emergency that requires an arrested landing at the field) and not going to full power upon touchdown (not prior) unless you are doing a touch and go landing (or FCLP-Field Carrier Landing Practice).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most navy fields that have carrier based aircraft will have an OLS system at the field for continued practice during most approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Attitude (Angle of Attack-AOA) is set near the start of the final approach as part of the landing checklist. This attitude has the tail hook at the lowest point and keeps the nose high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being on the back end of the 'power curve' with this high attitude, additionally keeps the aircraft speed over the ground slower and the power settings higher to maintain flying speed and prevent stall. Upon landing this thrust becomes excess thrust enabling the aircraft to more quickly accelerate and get safely airborne in the event of a bolter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally the higher thrust setting minimizes any spool up time because you are already near max thrust.&lt;/p&gt;&#xA;" OwnerUserId="2592" LastEditorUserId="65" LastEditDate="2015-03-03T15:38:03.953" LastActivityDate="2015-03-03T15:38:03.953" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6298" PostTypeId="1" AcceptedAnswerId="6299" CreationDate="2014-06-12T23:30:56.510" Score="6" ViewCount="585" Body="&lt;p&gt;ICAO, the International Civil Aviation Organization, has specifications for the conduct of civil aviation throughout the world. Such things as the language to be used between controllers and pilots, aircraft calls signs, and a host of other things are covered. At the time of my retirement in 1999, the ICAO specifications were merely recommendations, they did not have the force of regulation in the U.S. or, to the best of my knowledge, in any country in which I operated. Is that still true? Is there any country that says, essentially, that if ICAO says it should be so, the country treats that as a regulation.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="19" LastEditDate="2016-09-01T09:31:18.487" LastActivityDate="2016-09-01T09:31:18.487" Title="Do ICAO specifications have the force of regulation?" Tags="&lt;faa-regulations&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6299" PostTypeId="2" ParentId="6298" CreationDate="2014-06-12T23:43:42.627" Score="5" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.icao.int/about-icao/Pages/default.aspx&quot;&gt;About ICAO&lt;/a&gt; from their own site:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ICAO works with the Convention’s 191 Signatory States and global industry and aviation organizations to develop international Standards and Recommended Practices (SARPs) which are then used by States when they develop their legally-binding national civil aviation regulations. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So ICAO continues to develop standards and recommendations without the force of regulation.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-06-12T23:43:42.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6300" PostTypeId="1" AcceptedAnswerId="6307" CreationDate="2014-06-12T23:52:41.757" Score="5" ViewCount="3658" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;You've just received your private pilot certificate and your friends want to share the operating expenses of a flight with you.  There's a mother, a father, and their 6-month old baby. Do you split the cost of the flight among three people or four?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Obviously, the answer depends on the definition of &lt;em&gt;pro rata&lt;/em&gt;, but I can't find the definition of that term anywhere in the FARs. This term is used here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Where is the term &lt;em&gt;pro rata&lt;/em&gt; defined as it is used in 61.113(c)?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="675" LastEditDate="2014-06-13T00:22:13.887" LastActivityDate="2018-04-26T15:04:29.253" Title="Where is the term *pro rata* defined as it is used in 61.113(c)?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6302" PostTypeId="1" AcceptedAnswerId="6338" CreationDate="2014-06-13T06:59:23.207" Score="4" ViewCount="9305" Body="&lt;p&gt;Everywhere I look I'm only able to find information about airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do I find out the location of the &lt;em&gt;Aerodynamic centre&lt;/em&gt; of an arbitrary aircraft irrespective of its type or shape?&lt;/p&gt;&#xA;" OwnerUserId="2558" LastEditorUserId="247" LastEditDate="2014-06-16T10:06:32.107" LastActivityDate="2019-11-17T10:56:37.127" Title="How to find the location of the Aerodynamic centre?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6303" PostTypeId="1" AcceptedAnswerId="6304" CreationDate="2014-06-13T09:49:34.407" Score="21" ViewCount="3681" Body="&lt;p&gt;If a large passenger airliner needs repair at a remote airport without services, are there &quot;flying repairshops&quot; that can swoop in and do the work on site?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="247" LastEditDate="2014-06-14T13:38:53.427" LastActivityDate="2014-06-14T13:38:53.427" Title="How do you repair a grounded aircraft at a remote location?" Tags="&lt;airliner&gt;&lt;aircraft-maintenance&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6304" PostTypeId="2" ParentId="6303" CreationDate="2014-06-13T11:10:44.767" Score="24" Body="&lt;p&gt;If you can, you'll fly in maintance yourself to get it fixed, perhaps by chartering a cargo plane on the way. If you can land the aircraft, you can probably get any spare part in through the same runway, with varying degrees of difficulty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's bad, Boeing has an &lt;a href=&quot;http://www.airspacemag.com/flight-today/airliner-repair-247-9974457&quot;&gt;Aircraft On Ground team&lt;/a&gt; who should be able to fix pretty serious damage. Often, it may just be patched up until it's good enough to fly to get it to a place with better facilities.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-06-13T11:10:44.767" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6305" PostTypeId="2" ParentId="6303" CreationDate="2014-06-13T11:37:07.510" Score="10" Body="&lt;p&gt;That would depend on the damage that needs to be repaired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some repairs (like replacing an engine) can be done on site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more serious damage that can't be fixed on site they will make a quick patch and then fly the aircraft to a facility capable of properly doing the repairs while taking care to not aggravate the existing problem. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-06-13T11:37:07.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6306" PostTypeId="2" ParentId="6303" CreationDate="2014-06-13T14:17:03.653" Score="16" Body="&lt;p&gt;No airport capable of handling widebodies will have no services at all, but of course many places lack a full maintenance shop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned elsewhere, Boeing has a go team that can get most repairable damage brought back to flyable condition. &quot;Flyable&quot; does not necessarily mean &quot;normal, scheduled service&quot; - it means able to leave the remote field and limp back to a facility able to do the proper work. This could easily be Seattle or Hamburg from Johannesburg. If you want to reposition an aircraft for maintenance you can have a LOT of stuff broken - basically if the engineers say they'll ride in it, and you avoid overflying large cities, you're good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several large aircraft have an option to carry an extra engine on the wing to a remote grounded aircraft - expensive, but cheaper than cargo (it can be on a scheduled revenue flight). Put a couple of mechanics on board and the job's done in a day or two. The bad engine comes back the same way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/abnHA.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-13T14:17:03.653" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6307" PostTypeId="2" ParentId="6300" CreationDate="2014-06-13T16:03:20.797" Score="5" Body="&lt;p&gt;&lt;code&gt;pro rata&lt;/code&gt; in law generally means according to a calculation or apportionment formula - in the context of the FARs that formula is generally assumed to be $\left(\frac{1}{nOccupants}\right)$ as Hugh noted.&lt;br&gt;&#xA;I actually went on a dive through &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/&quot;&gt;FAA counsel opinions&lt;/a&gt; on how they deal with the &lt;em&gt;pro rata&lt;/em&gt; bit and found nothing applicable to this situation, so what follows is an interpretation crafted out of my own slightly deranged mind, but it seems sensible to me.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Interestingly while digging around I found nothing in the FARs or interpretations that would seem to preclude &lt;a href=&quot;http://www.samoaair.ws/index.php/booking-2/pay-by-weight&quot;&gt;a more complex formula&lt;/a&gt; for &lt;em&gt;pro rata&lt;/em&gt; share than &quot;divide by the number of people in the plane&quot;, but neither is there anything I can find to support doing so, and I imagine it would be much harder to justify to your local FSDO if questions came up.&lt;br&gt;&#xA;  For the sake of simplicity (and our collective sanity) let's stick with &quot;simple division&quot; as the formula.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FARs specify that the pilot may not pay &lt;em&gt;less&lt;/em&gt; than their pro rata share of operating expenses associated with the flight.  So, if we have 4 occupants of the aircraft (Mom, Dad, Baby, and Pilot) and they go for a hundred-dollar hamburger the simple division method says pilot cannot pay less than one-fourth of the &lt;em&gt;operating expenses&lt;/em&gt; associated with the flight.  If we say the expenses work out to be \$100 (for the sake of easy math) the pilot has to pay &lt;em&gt;at least&lt;/em&gt; \$25.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA doesn't much care where the rest of the money comes from because it's implicit in the regulations that the pilot isn't keeping it (the money would be going into the hands of the FBO for fuel, oil, ramp fees, etc.) -- Mom &amp;amp; Dad could pay $37.50 each (covering themselves plus the baby) or split it up between themselves in any other way they wish and this is still acceptable under the regulations as long as the pilot has paid their &lt;em&gt;pro rata share&lt;/em&gt; of the expenses.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The pilot can certainly pay more than the simple-divison &lt;em&gt;pro rata&lt;/em&gt; share of expenses (and generally that's the most equitable option - figure out who's paying, divide by that number, and make sure the pilot is in the &quot;paying&quot; group to stay on the right side of the regulations).&lt;br&gt;&#xA;In your example you would split the cost up among the three adults (each paying $33.33, and the pilot generally kicking in the extra penny).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same logic in both of these arguments would apply if we weren't talking about a baby, but rather a third friend that you all decided to treat to a trip.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-13T16:03:20.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6308" PostTypeId="1" AcceptedAnswerId="6311" CreationDate="2014-06-13T18:24:43.300" Score="3" ViewCount="206" Body="&lt;p&gt;I'm writing software to integrate a weight and balance chart into my website. Most of the &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow&quot;&gt;Type Certificate Data Sheets TCDS&lt;/a&gt; I've read follow the form:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;x&lt;/em&gt; to &lt;em&gt;y&lt;/em&gt; at &lt;em&gt;z&lt;/em&gt; lbs. or less&lt;br&gt;&#xA;&lt;em&gt;a&lt;/em&gt; to &lt;em&gt;b&lt;/em&gt; at &lt;em&gt;c&lt;/em&gt; lbs.&lt;br&gt;&#xA;Straight line variation between points given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to make sure that I test this against more complex scenarios.  Are there general aviation aircraft that have more than 2 &quot;ranges&quot; or are otherwise exceptional that would make for good test cases?  I am only concerned with GA aircraft at this time.&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="65" LastEditDate="2015-02-26T18:36:06.597" LastActivityDate="2015-02-26T18:36:06.597" Title="How are weight ranges mentioned for GA airplanes in TCDS?" Tags="&lt;general-aviation&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6309" PostTypeId="2" ParentId="6303" CreationDate="2014-06-13T19:55:27.850" Score="23" Body="&lt;p&gt;If the problem is a bad engine and the aircraft is a 747, the most cost effect solution is usually a 3-engine ferry to a repair station. From memory, the protocol to be observed includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Captain must do the flying.&lt;/li&gt;&#xA;&lt;li&gt;Only the cockpit crew can be aboard.&lt;/li&gt;&#xA;&lt;li&gt;The fan must be tied down to prevent it's rotation in flight.&lt;/li&gt;&#xA;&lt;li&gt;A specific takeoff procedure is to be followed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At the two 747 carriers I worked for, we usually did a 3-engine takeoff in the sim on our 6-month checks. I did two of them for real, and it's no big deal.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-06-13T19:55:27.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6310" PostTypeId="1" CreationDate="2014-06-13T20:12:25.453" Score="8" ViewCount="774" Body="&lt;p&gt;While browsing the major accidents in the Aviation Security Network's database, I noticed that a &lt;a href=&quot;https://www.google.de/search?q=site%3aaviation-safety.net%20deactivated%20reverser&quot;&gt;couple of accidents&lt;/a&gt; seem to at least be aggravated by one-sided deactivation of thrust reversers. One-sided thrust reverser deactivation seemed to be permissible according to the respective Minimum Equipment Lists, yet the reports indicate that the crews have been caught off guard by the resulting asymmetric thrust after reverser activation during landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As some of the mentioned accidents resulted in a high number of fatalities, I wonder if the procedures and requirements regarding thrust reverser deactivation have ever been changed. How common is it for an airliner on a commercial flight to have thrust reversers deactivated asymmetrically nowadays?&lt;/p&gt;&#xA;" OwnerUserId="2600" LastEditorUserId="19" LastEditDate="2017-01-25T14:23:39.753" LastActivityDate="2017-01-25T14:23:39.753" Title="Is one-sided thrust reverser deactivation still allowable?" Tags="&lt;accidents&gt;&lt;thrust-reverser&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6311" PostTypeId="2" ParentId="6308" CreationDate="2014-06-13T21:11:14.237" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there general aviation aircraft that have more than 2 &quot;ranges&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/af90bd3d08b5d26e8625720a0054405a/$FILE/2A13.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;I happen to fly one (the PA-28 series, TCDS 2A13)&lt;/a&gt;.&lt;br&gt;&#xA;The loading graphs look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sfC6r.png&quot; alt=&quot;PA28 loading graphs &amp;amp; ranges&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that the aircraft is certificated in both the Normal and Utility category, and the weight/CG ranges are different (Utility being a subset of what's permissible for Normal category operations) - so there are two different operating envelopes that must be considered.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-13T21:11:14.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6312" PostTypeId="1" AcceptedAnswerId="6315" CreationDate="2014-06-13T22:21:24.033" Score="41" ViewCount="38597" Body="&lt;p&gt;Replacing airframe panels and inspecting hard-to-reach parts would be easier with screws, I presume. So why are rivets used?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2020-12-03T11:17:28.057" Title="Why are airplanes riveted and not screwed?" Tags="&lt;aircraft-design&gt;" AnswerCount="7" CommentCount="7" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6313" PostTypeId="2" ParentId="6312" CreationDate="2014-06-13T22:33:48.390" Score="6" Body="&lt;p&gt;Flush rivets are used on aircraft for aerodynamic reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rivets stand up to vibration better than normal screws.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-06-13T22:33:48.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6314" PostTypeId="2" ParentId="6312" CreationDate="2014-06-13T22:35:57.187" Score="51" Body="&lt;ul&gt;&#xA;&lt;li&gt;They are &lt;strong&gt;cheap and simple&lt;/strong&gt;, especially in the volumes needed.&lt;/li&gt;&#xA;&lt;li&gt;They are &lt;strong&gt;impossible to open&lt;/strong&gt;, a useful safety consideration. You only have to check that they are properly inserted from the beginning. They won't shake loose.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Flush rivets are aerodynamically good&lt;/strong&gt; since they can be made flush with the fuselage, which is difficult (or possible?) with bolts I believe.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;(Blind) rivets are great for complex structures, since you can apply them entirely from the one side.&lt;/strong&gt; You &lt;em&gt;might&lt;/em&gt; be able to use screws if you pre-inserted them and held the thread and rotated the nut, but the nuts would still be outside the skin in the end.&#xA;&lt;img src=&quot;https://n999za.files.wordpress.com/2011/07/20110729-002-large.jpg&quot; alt=&quot;wing&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;Furthermore, I believe a protective coating is applied between many (commercial) aircraft panels for moisture and corrosion protection, so you wouldn't want to take them off to start with.&lt;/li&gt;&#xA;&lt;li&gt;There's very seldom any reason to start taking apart aircraft. If it's bad, you can rivet over it or drill out the rivet.&lt;/li&gt;&#xA;&lt;li&gt;Rivets can be made a bit smaller than bolts, saving weight. (&lt;em&gt;Not entirely confident on this one&lt;/em&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Replacing airframe panels and inspecting hard-to-reach parts would be&#xA;  easier with screws, I presume.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Every time you make a hatch it introduces a weak spot into the loaded airframe, such as the skin covering the wings and the cabin, it has to be reinforced to bring it up to the required strength, adding weight. That's why these are kept to a bare minimum.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That's not to say aviation doesn't use screws or has its own versions. One screw derivative is called a hi-lok and is a permanent joining like a rivet. It works much like a classic bolt but has a calibrated diameter between the top hex nut and the bottom nut, so it snaps off when it reaches the correct torque. That way it's got a safety guarantee being attached well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i1.ytimg.com/vi/2Fzwb-B-chk/maxresdefault.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.133" LastActivityDate="2014-06-14T17:45:43.863" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="6315" PostTypeId="2" ParentId="6312" CreationDate="2014-06-14T00:14:50.363" Score="55" Body="&lt;p&gt;Rivets need to press the two parts together AND to transmit shear. The pressure results in friction which is responsible for a considerable part of the load transmitted between two riveted panels. In order to hold up to the maximum possible amount of shear, the rivet needs a smooth surface. A thread would make it much more vulnerable due to the notch effect of the thread.&lt;/p&gt;&#xA;&lt;p&gt;Since skin panels and flanges vary in thickness, a LOT of different screw sizes would need to be kept on stock so that every combination of panel thicknesses is covered with a fitting screw which has just the right amount of smooth shank length. Rivets, on the other hand, will be hammered to the right length during manufacture, so only a few sizes are needed to cover all those panel thicknesses.&lt;/p&gt;&#xA;&lt;p&gt;Historically, metalworking tools were much less precise than today. For optimum shear transmission, the bolt must sit tightly in its hole. In the past, this could  not be done with screws, but only with rivets which grow thicker when set in place. And since aviation regulation authorities are VERY conservative, the easiest to certify joints are those proven rivet joints.&lt;/p&gt;&#xA;&lt;p&gt;Repairability is adequate when using rivets, especially if you can reach only one side. The rivets are drilled out with a drill bit which has a diameter slightly smaller than the original hole size. Great care is taken not to oversize their original hole. The rivets are then, in the case of sufficiently thick material, tapped out with a hammer and punch. If the material is too thin or fragile to allow a punch and hammer to be used, the rivet will be drilled out with a drill bit that matches the original size of the rivet hole, with great care taken not to oversize the hole. If the hole is damaged or oversized in the removal process, a larger hole may be drilled and corresponding rivet installed, depending on the conditions present. After inspection or repair the parts are riveted together again.&lt;/p&gt;&#xA;&lt;p&gt;If you need the lowest mass for a given strength, again rivets win over screws. The difference might be small for the individual rivet, but it adds up for the whole airframe.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2020-12-03T11:17:28.057" LastActivityDate="2020-12-03T11:17:28.057" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="6318" PostTypeId="2" ParentId="53" CreationDate="2014-06-14T07:04:49.547" Score="3" Body="&lt;p&gt;Yep, the 3rd party route is easiest. We've used World Air Ops (Canada) for this in the past, &lt;a href=&quot;http://www.worldairops.com/permits/cuba.html&quot; rel=&quot;nofollow&quot;&gt;http://www.worldairops.com/permits/cuba.html&lt;/a&gt;. For our aircraft (CL601) the Nav fee was around $150.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The application fee $50 or so.&lt;/p&gt;&#xA;" OwnerUserId="2606" LastActivityDate="2014-06-14T07:04:49.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6319" PostTypeId="1" CreationDate="2014-06-14T09:34:56.240" Score="21" ViewCount="19237" Body="&lt;p&gt;I've observed that almost all military transports have high wings (with a pronounced anhedral) and almost all civilian airliners have low wings (with a pronounced dihedral) &amp;mdash; why is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high-wing configuration gives the military the advantage of easier loading and unloading (especially when operating from irregular airfields), and lower overall height for the aircraft, but then why do civilian aeroplanes hate this design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except in the erstwhile USSR, I haven't really seen high-winged military aircraft being used as civilian airliners (Boeing 737 size and beyond), though I can't think of any reasons why not.&lt;/p&gt;&#xA;" OwnerUserId="2607" LastActivityDate="2017-12-14T04:41:28.933" Title="Why do (almost) all military transports have high wings and civilian transports low wings?" Tags="&lt;wing&gt;&lt;military&gt;&lt;fixed-wing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6320" PostTypeId="1" AcceptedAnswerId="6352" CreationDate="2014-06-14T15:01:23.363" Score="7" ViewCount="1172" Body="&lt;p&gt;What are the relevant regulations regarding use of HUD displays in non-military aviation? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific application in mind would involve providing information to pilots of turboprop survey aircraft flying VFR at about 100m altitude so it's of benefit to have the pilots' focus on what's going on out the window. &lt;/p&gt;&#xA;" OwnerUserId="2055" LastEditorUserId="19" LastEditDate="2017-01-16T13:47:47.073" LastActivityDate="2017-01-16T13:47:47.073" Title="What are the rules regarding (HUD) Head-up displays, especially glasses type?" Tags="&lt;faa-regulations&gt;&lt;avionics&gt;&lt;visual-flight-rules&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6321" PostTypeId="2" ParentId="6312" CreationDate="2014-06-14T18:05:34.833" Score="2" Body="&lt;ol&gt;&#xA;&lt;li&gt;Rivet Joints have more shock absorbing capacity, &lt;/li&gt;&#xA;&lt;li&gt;They absorb shear stress better,&lt;/li&gt;&#xA;&lt;li&gt;They are more leak proof and&lt;/li&gt;&#xA;&lt;li&gt;They are permanent joints.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2611" LastActivityDate="2014-06-14T18:05:34.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6322" PostTypeId="2" ParentId="6319" CreationDate="2014-06-14T18:45:32.130" Score="14" Body="&lt;p&gt;For military transport aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wings further off the ground will mean that the engines will also be further off the ground, reducing the risk of foreign object damage.&lt;/li&gt;&#xA;&lt;li&gt;You can move vehicles under the wing, and taxi across smaller taxiways.&lt;/li&gt;&#xA;&lt;li&gt;The fuselage can be closer to ground, facilitating transport.&lt;/li&gt;&#xA;&lt;li&gt;No wing spar crossing the cargo floor.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Reasons why most commercial transport jets don't have it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Many are converted passenger jets.&lt;/li&gt;&#xA;&lt;li&gt;They are mainly pallet loaded, less vehicles and bulky objects.&lt;/li&gt;&#xA;&lt;li&gt;They normally use prepared airports, which military jets cannot assume they will.&lt;/li&gt;&#xA;&lt;li&gt;They often loaded from a side door, and it makes little difference I think if you go up one meter or three meters.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;but then why do civilian aeroplanes hate this design?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airlines don't 'hate' this design, look at the BAe146 Quiet Trader for instance. It's just not that many commercial aircraft from which cargo jets are derived are built this way.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except in the erstwhile USSR, I haven't really seen high-winged military aircraft being used as civilian airliners (Boeing 737 size and beyond), though I can't think of any reasons why not.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Military jets are very expensive to operate and the east block Antonov 124 probably satisfy the most demand. There are a few commercial C130 (L100) around though. It's also not like the US airforce will give us C-5 Galaxy to a commercial company to do whatever it wants with it.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-06-14T18:56:35.187" LastActivityDate="2014-06-14T18:56:35.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6323" PostTypeId="2" ParentId="6312" CreationDate="2014-06-14T20:08:53.303" Score="15" Body="&lt;p&gt;Vibrating loose is the major concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The panels are generally made from two sheets of aluminum skin (.030 - .060 thick)  with a paper honeycomb bonded between them and solid aluminum rails from 1&quot; - 3&quot; wide at the edges. This makes the panels incredibly resistant to flex or compression spread over the surface  and extremely lightweight. (You could easily, however shove a pencil through the middle of it (not recommended to try in-flight))&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using screws would  a) easily distort the surface of the panels (consider the way a screw is applied (torsion, which causes it to pull itself in) vs a rivet (which only applies force against itself until near-full compression is reached) or b) be highly susceptible to vibrating loose ( particularly since the skin is too thin to contain even a single thread )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to use screws into the solid edges, but you still have the risk of vibrating loose, plus the manufacturing costs of threading holes or using capture-nuts.&lt;/p&gt;&#xA;" OwnerUserId="2614" LastEditorUserId="64" LastEditDate="2014-06-15T03:51:50.773" LastActivityDate="2014-06-15T03:51:50.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6324" PostTypeId="1" CreationDate="2014-06-15T02:55:40.573" Score="2" ViewCount="1300" Body="&lt;p&gt;I was watching &lt;em&gt;World War Z&lt;/em&gt; and when they were bailing out of Israel, a bunch of armed troops held up a Belarus Ariways Airbus A310 right on the runway.  The pilots dropped a ladder out from near the front of the plane and our heroes climbed up out of danger and directly into the cockpit.  Is this a real thing or just Plot Device&amp;trade;?&lt;/p&gt;&#xA;" OwnerUserId="1032" LastActivityDate="2014-06-15T02:55:40.573" Title="Do airliners have integrated ladders that lead right into the cockpit?" Tags="&lt;airliner&gt;&lt;airbus&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2014-06-15T21:21:21.293" ContentLicense="CC BY-SA 3.0" />
  <row Id="6325" PostTypeId="1" AcceptedAnswerId="6328" CreationDate="2014-06-15T09:21:56.530" Score="4" ViewCount="1970" Body="&lt;p&gt;What type of microcontrollers (in terms of processing power, clock speed) are used in large scale UAVs such as the Northrop Grumman RQ-4 Global Hawk, the General Atomics MQ-1 Predator etc. ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, are smaller, low powered microcontrollers used for controlling subsystems such as the INS and control surface movements. If so, then in what range does their processing power and clock frequency lie?&lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="19" LastEditDate="2016-06-22T07:56:23.140" LastActivityDate="2016-06-22T07:56:23.140" Title="What type of microcontrollers are used in large scale UAVs?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6326" PostTypeId="1" AcceptedAnswerId="6349" CreationDate="2014-06-15T14:16:08.620" Score="4" ViewCount="4268" Body="&lt;p&gt;I'm currently trying to locate the Master Minimum equipment list for an Airbus 321.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have the FAA (US) version of this document, but I'd like a copy of the UK or EUR version if possible.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The Master Minimum Equipment List page on CAA doesn't contain a link to the any airbus series&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=33&amp;amp;pagetype=65&amp;amp;appid=11&amp;amp;mode=list&amp;amp;type=sercat&amp;amp;id=16&quot; rel=&quot;nofollow&quot;&gt;http://www.caa.co.uk/application.aspx?catid=33&amp;amp;pagetype=65&amp;amp;appid=11&amp;amp;mode=list&amp;amp;type=sercat&amp;amp;id=16&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a page on the flight safety committee that contains 5 historical links to lists for the A320 series aircraft. But all of these links are dead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ukfsc.co.uk/information/caa-notifications/275-caa-master-minimum-equipment-list-amendements-mmel&quot; rel=&quot;nofollow&quot;&gt;http://www.ukfsc.co.uk/information/caa-notifications/275-caa-master-minimum-equipment-list-amendements-mmel&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Can anyone point me in the right direction as to where I can find this document? I would prefer the revision that was current in September 2013 for UK and Europe.&lt;/p&gt;&#xA;" OwnerUserId="2275" LastEditorUserId="13197" LastEditDate="2016-04-26T14:20:37.800" LastActivityDate="2016-04-26T14:20:37.800" Title="Where Can I Find the Master Minimum Equipment List for the A320 Series (UK / EUR)?" Tags="&lt;easa-regulations&gt;&lt;equipment&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6327" PostTypeId="1" AcceptedAnswerId="6330" CreationDate="2014-06-15T18:22:52.643" Score="5" ViewCount="1068" Body="&lt;p&gt;There were multiple severe accidents briefly after the entry into service of the A320, many involving to varying degree the augmented control system as a cause. In my eyes the A320 seems to have a very aggressive manipulation of the aircraft controls historically early (1987).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, the introduction of composites of the Boeing 787 generated a lot of stir and questions about safety, repairs, and lifespan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Was there ever any questioning of the Airbus augmented control prior to the introduction to service?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-06-15T18:28:05.780" LastActivityDate="2014-06-17T10:12:14.840" Title="Was the introduction of the A320 flight control system controversial?" Tags="&lt;flight-controls&gt;&lt;airbus&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6328" PostTypeId="2" ParentId="6325" CreationDate="2014-06-16T04:59:17.300" Score="5" Body="&lt;p&gt;Airbus used standard Intel 80186 and Motorola 68010 CPUs with 2.5MiB of memory in the FBW system for A320. Exactly the same chips that were used for computers at the time (around 1985) so they were not expensive and were already tested. Over time they upgraded to newer version of those CPUs. Each computer is composed from two boards with different CPUs, one produces the control output and the other verifies it and shuts the unit down if they disagree. The boards run different standard embedded operating systems and the software was written by two independent teams to minimize risk of the same failure mode in both boards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each board only does a little bit of work and the important units have backups. There are 4 units processing the sidestick input, 3 controlling elevator and ailerons, 3 controlling spoilers and elevator trim, IIRC 2 for yaw damper (FAC), 2 for each engine digital control, 1 for each display etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirements didn't really increase much since then. It is still desired that the tasks are split across many independent boards to minimize effects of one of them failing. So a CPU with few MHz clock rate and few MB of memory would still be able to do the job. But such slow chips are not manufactured anymore, so they are probably using whatever was most common chips few years ago.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-06-16T04:59:17.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6330" PostTypeId="2" ParentId="6327" CreationDate="2014-06-16T09:27:09.673" Score="7" Body="&lt;h2&gt;Summary&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;No. The aspects that are talked about now are not the ones talked about then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My (hazy) recollection is of concerns that the A320 lacked a system of cables and pulleys of the sort used by the Wright brothers. Perhaps pilots of the time had more focused concerns but I don't recall them making the front pages of newspapers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1980s there was discussion of Airbus flight control systems but the discussion focused on factors that were not involved in the most notable A320 crashes in the late '80s and early 90's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several Airbus accidents seem to be at least partly the result of pilots lack of familiarity with sophisticated aircraft systems in general rather than with features that are not found in other aircraft. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Airbus control system&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The main innovations by Airbus were the application to civil airliners of designs that had previously only been used on other types of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fly by wire. No mechanical cables, pulleys and associated friction.&lt;/li&gt;&#xA;&lt;li&gt;Sidesticks. To provide clearer view of displays and greater pilot comfort.&lt;/li&gt;&#xA;&lt;li&gt;Flight envelope protection. To prevent excessive inputs stalling or damaging the airframe.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Transfer of control&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus spent some time comparing and investigating support for transfer of control between pilots, including in emergency situations. They investigated pilot preferences for several approaches to this. They revisited this aspect over the years and it has become a point of focus since the AF447 report. However it doesn't seem to have been a particular point of controversy in 1987. Perhaps few people in the 1980s fully realized the extent to which pilots can operate independently and antagonistically in severe emergencies and the degree to which teamwork and communication disappears.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;There were multiple severe accidents briefly after the entry into service of the A320&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You mean these:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;26 June 1988, &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_296&quot;&gt;Air France 296&lt;/a&gt;. Pilots flew aircraft into trees during unrehearsed demonstration flight at unfamiliar aerodrome after mistaking trees for grass on approach.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;14 February 1990 &lt;a href=&quot;http://en.wikipedia.org/wiki/Indian_Airlines_Flight_605&quot;&gt;India Air 605&lt;/a&gt;. Idle/open descent mode engaged and pilots failed to act as aircraft descended into terrain near airport.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;20 January 1992 &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Inter_Flight_148&quot;&gt;Air Inter 148&lt;/a&gt;. Aircraft flown into terrain after autopilot incorrectly put into vertical speed mode and entered numbers appropriate for flight-angle mode. Air Inter had chosen not to equip aircraft with ground proximity warning system.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The total number of hull-loss accidents for the 320 doesn't seem high compared to other aircraft, but it's hard to compare the numbers if you don't take into account fleet size, cycles flown etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;the A320 seems to have a very aggressive manipulation of the aircraft controls&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure what you mean by &quot;aggressive manipulation&quot; but that seems an extreme view. The Airbus systems are a progressive development of existing trends. The accidents were largely the result of pilots setting inappropriate modes in systems like the autopilot. The accidents apparently didn't arise because of, for example, the way the control sticks operate.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Was there ever any questioning of the Airbus augmented control prior to the introduction to service?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;By &quot;augmented control&quot; I guess you mean features like the flight envelope protection that prevents pilot inputs from overloading the airframe. That doesn't seem to have been controversial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only controversy was over two items that had been used in military aircraft but not in commercial passenger aircraft&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;fly by wire&lt;/li&gt;&#xA;&lt;li&gt;sidesticks&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These don't seem to have been a large factor in the specific accidents mentioned above.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Further reading:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://lessonslearned.faa.gov/IndianAir605/A320%20Final%20Special%20Condition.pdf&quot;&gt;Indian AIr 605 - A320 Special Final Conditions - FAA&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://criticaluncertainties.com/2011/09/16/pilots-in-the-loop-airbus-and-the-fbw-side-stick/&quot;&gt;Pilots in the loop?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_12.pdf&quot;&gt;Electrical Flight Controls&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://philip.greenspun.com/book-reviews/fly-by-wire&quot;&gt;Fly by Wire&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/4040971/&quot;&gt;AF447&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-17T10:12:14.840" LastActivityDate="2014-06-17T10:12:14.840" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6331" PostTypeId="1" AcceptedAnswerId="6339" CreationDate="2014-06-16T09:41:44.543" Score="-2" ViewCount="1021" Body="&lt;p&gt;What should be the ratio of the fuselage and wings in a maximum dimension limited condition supersonic delta wing aircraft?&#xA;Also can anybody explain clearly the &quot;supersonic area rule&quot; or &quot;Whitcomb area rule&quot;?&#xA;Is there anything else I need to take care of while designing a fuselage for supersonic conditions?&#xA;Thanks.&lt;/p&gt;&#xA;" OwnerUserId="2558" LastActivityDate="2014-08-13T12:03:37.747" Title="Supersonic Fuselage design" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-06-16T22:23:24.567" ContentLicense="CC BY-SA 3.0" />
  <row Id="6333" PostTypeId="1" AcceptedAnswerId="6335" CreationDate="2014-06-16T11:46:46.737" Score="5" ViewCount="767" Body="&lt;p&gt;Background: I'm a huge aviation enthusiast with a lapsed PPL. Have flown some larger aircraft on MSFS, but never flown anything in real life bigger than a C172. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was lucky enough to do a bit of Simulator time on a B737 simulator this weekend. One thing I wanted to try out was an ILS approach in very limited visibility. The instructor set me up, and asked what ILS display I was &quot;used to seeing&quot;. I described it, and she set it to this - totally what I was expecting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/709xR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(Thats the purple vertical bar for centre line and purple blip for glide slope).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question is, what was the &quot;Other&quot; option? This may be specific for a B737, or it may not. Why are there 2 types of instrumentation for an ILS approach? Is one a newer system, and is it therefore preferred.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="572" LastEditDate="2015-02-19T09:24:56.943" LastActivityDate="2015-02-19T09:24:56.943" Title="What are the different variants of ILS intrumentation?" Tags="&lt;flight-instruments&gt;&lt;boeing&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6334" PostTypeId="2" ParentId="6333" CreationDate="2014-06-16T12:17:37.843" Score="2" Body="&lt;p&gt;That would be the double needle display. Here are the 3 most common displays:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/66LNd.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.kispo.net/fsportugal/p8-2i.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one on the left is the one you are used to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;the one in the middle is the classic double needle design where each line pivots on the point at the top or on the left. The one on the right is equivalent to the one in the middle except that the bars don't rotate but just move up and down and left and right.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-06-16T12:17:37.843" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6335" PostTypeId="2" ParentId="6333" CreationDate="2014-06-16T15:10:30.557" Score="6" Body="&lt;p&gt;In the Boeing next-generation &quot;NG&quot; flight decks, the PFD can be configured one of two ways. The first way, is the default presentation, where you only see to top of the HSI. The pilot will fly the aircraft via the pips along the bottom and right of the attitude indication (and usually with the flight director cross as well):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iDwUZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If my memory is correct, Boeing, NASA, and others did a number of human factors studies over the years and found that this layout allowed pilots to more quickly understand critical flight information, and this layout is now standard even in GA glass cockpits (e.g. Garmin G1000, Collins Proline).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second configuration provides a virtual &quot;six-pack&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q66qp.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This configuration is primarily used for airlines that are transitioning between &quot;Classic&quot; and &quot;NG&quot; flight decks. One airline I remember in particular is Southwest, as they had a combination of 737-300/400 and -700/800 aircraft and having a classic configuration on their new flight decks allowed all of their pilots to fly any of the aircraft, without needing significant differences training. The particular presentation can be customized per the airline's needs. An airline will typically move exclusively to the modern PFD display once all of the older aircraft are moved out of the fleet.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2014-06-16T15:10:30.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6336" PostTypeId="1" AcceptedAnswerId="6340" CreationDate="2014-06-16T17:49:08.053" Score="31" ViewCount="6409" Body="&lt;p&gt;For example, the following white and orange striped ramp:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RvXl1.jpg&quot; alt=&quot;ramp&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen these at a couple large airports but I've never seen them actually used for anything.&lt;/p&gt;&#xA;" OwnerUserId="261" LastActivityDate="2020-04-27T17:56:41.897" Title="What are the steep ramps often erected at large airports?" Tags="&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6337" PostTypeId="2" ParentId="6336" CreationDate="2014-06-16T17:59:53.067" Score="8" Body="&lt;p&gt;The following is speculation, as I have no specific knowledge on the matter, but searching a bit it seems that they are needed for deflecting upwards the engine blast&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bdi.aero/&quot;&gt;http://www.bdi.aero/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it seems from that website that they also provide a minimum of noise abatement.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-06-16T17:59:53.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6338" PostTypeId="2" ParentId="6302" CreationDate="2014-06-16T18:16:55.860" Score="6" Body="&lt;p&gt;What you refer to as the aerodynamic centre is also called the neutral point, the point where pitch moments do not change at all angles of attack with attached airflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ask for an unswept body of high aspect ratio, the answer would be easy: At the quarter chord point in subsonic flow and at the half chord point in supersonic flow. Unfortunately, the neutral point shifts forward with decreasing aspect ratio until it sits right at the leading point (not edge) of a slender body, a body with infinitesimally small aspect ratio. It shifts slightly backwards with positive sweep, so you normally have to calculate correction factors which depend on&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sweep angle&lt;/li&gt;&#xA;&lt;li&gt;Taper ratio&lt;/li&gt;&#xA;&lt;li&gt;Ratio of fuselage width and span&lt;/li&gt;&#xA;&lt;li&gt;Lengthwise position of the wing-fuselage intersection&lt;/li&gt;&#xA;&lt;li&gt;High wing or low wing configuration (negligible influence)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you don't have good wind tunnel data or a validated CFD model, you would use a collection of formulas and diagrams like DATCOM (see this &lt;a href=&quot;http://www.pdas.com/datcom.html&quot;&gt;link for a computerized version&lt;/a&gt;) to approximate a solution. Sorry, but I cannot give you a simple formula which would work out of the box.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-06-16T18:16:55.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6339" PostTypeId="2" ParentId="6331" CreationDate="2014-06-16T22:19:08.143" Score="2" Body="&lt;p&gt;There is no ideal ratio. Make the wing as big as it needs to be for your take-off run, your cruising altitude or your approach speed, whatever demands the biggest wing, and make the fuselage just big enough to hold the pilot(s) and all equipment, payload, fuel and whatever you choose to carry around. Asking for a specific ratio without any details on the mission or the design parameters is silly.&#xA;&lt;P&gt;&#xA;The comments tell me I should say something about area ruling, though. Terry correctly mentions the x-wise gradient of the aircraft's cross section, but this is only helpful at Mach 1. At higher speeds, you need to look at the area which is covered by Mach cones which run along the longitudinal axis. Sum up the area of the intersection between those Mach cones and your aircraft's structure, and make the lengthwise distribution follow a &lt;a href=&quot;http://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body&quot; rel=&quot;nofollow&quot;&gt;Sears-Haack-body&lt;/a&gt;. Please note that the inclination of those Mach cones varies with angle of attack, so there is not a single optimum shape, but only a best compromise for all expected flight conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Area ruling is only helpful around Mach 1, but there (or slightly above) is the transsonic drag maximum, and area ruling helps to get across this quickly, even with the high thrust of modern engines. If your task is to get to this strange radar blip at 16 km altitude in a hurry, every second counts. Also, modern airliners need to employ area ruling techniques to make cruise Mach numbers above Mach 0.8 economical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this is just scratching the surface ...&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-13T12:03:37.747" LastActivityDate="2014-08-13T12:03:37.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6340" PostTypeId="2" ParentId="6336" CreationDate="2014-06-17T02:09:22.883" Score="37" Body="&lt;p&gt;Here in the United States these are called blast fences.  They protect whatever may be behind them from the direct effects of jet blast by directing the blast upwards.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-06-17T02:09:22.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6341" PostTypeId="1" AcceptedAnswerId="6342" CreationDate="2014-06-17T02:14:43.143" Score="17" ViewCount="19940" Body="&lt;p&gt;WAAS LPV approaches can have decision altitudes as low as 200 AGL, the same as many Cat I ILS approaches. Previous opinions on the Internet have quoted the FAA as saying LPV is considered a non-precision approach, but many of these entries were made more than seven years ago, when the technology was much less mature. Does anyone know if this is still the FAA's position, and are there any RECENT references to their position?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="247" LastEditDate="2014-06-17T10:48:04.540" LastActivityDate="2019-02-07T23:28:21.897" Title="Is LPV considered a precision approach?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;gnss&gt;&lt;non-precision-approach&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6342" PostTypeId="2" ParentId="6341" CreationDate="2014-06-17T02:32:55.067" Score="17" Body="&lt;p&gt;LPV, LNAV/VNAV, and Baro VNAV are considered to be an 'Approach with Vertical Guidance (APV)'. These types of approaches are differentiated from 'Precision' approaches (ILS, PAR, etc.) in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AIM&lt;/a&gt; (Section 5-4-5, Paragraph 7):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Approach with Vertical Guidance (APV). An instrument approach based on a navigation system that is not required to meet the precision approach standards of ICAO Annex 10 but provides course and glidepath deviation information. For example, Baro−VNAV, LDA with glidepath, LNAV/VNAV and LPV are APV approaches.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="287" LastEditorUserId="14897" LastEditDate="2019-02-07T23:28:21.897" LastActivityDate="2019-02-07T23:28:21.897" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="6343" PostTypeId="2" ParentId="2042" CreationDate="2014-06-17T02:51:46.220" Score="8" Body="&lt;p&gt;&lt;strong&gt;C-130 Addendum&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Purpose-designed for cargo - rather novel at the time back then, perhaps. Look at WWII films of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_C-47_Skytrain&quot; rel=&quot;noreferrer&quot;&gt;C-47&lt;/a&gt; or Berlin Airlift film of &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_C-54_Skymaster&quot; rel=&quot;noreferrer&quot;&gt;C-54&lt;/a&gt;'s. How the heck do they get anything in there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designed around a &quot;standard truck bed height&quot; floor and a &quot;standard railroad box car&quot; dimensions - 10' x 10'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short landing gear derives from the basic design goals. Further, the wheels are in &lt;em&gt;tandem&lt;/em&gt; - one behind the other vice side by side. And the tires are fat. These aid operating out of unimproved/dirt fields. The leading tire &quot;plows the way&quot; so to speak for the rear tire. Fat tires lowers the &quot;per square foot&quot; weight on the tires.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The longer you make the gear, the more it will bend. Bad news if you're trying to land on rough ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ironically the C-130 landing gear is wimpy when it comes to side loads. It does not have adequate side-bracing. Straight ahead, we can pretty much plop that puppy on the ground relatively aggressively. But, during taxi, stopping while still in a turn is a write-up and requires maintenance inspection prior to flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The first possibility that jumps to mind is that one is more comfortable than the other, &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The C-130 is designed for utility, by masochists. It is painfully loud, too cold and too hot at the same time, vibrates like the inside of a jack hammer; and if the the prop synchro-phaser ever fails will drive you insane in short order.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastEditorUserId="946" LastEditDate="2014-06-17T10:14:19.313" LastActivityDate="2014-06-17T10:14:19.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6344" PostTypeId="2" ParentId="6336" CreationDate="2014-06-17T06:43:54.377" Score="25" Body="&lt;p&gt;Apart from blast fences, they also serve as wind breaks and to deflect engine noise away from the area behind them.&lt;br/&gt;&#xA;And of course they can (and the one you showed looks like it might be) intended to be a visible marker of a closed taxiway or runway.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-06-17T06:43:54.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6345" PostTypeId="1" AcceptedAnswerId="6346" CreationDate="2014-06-17T08:33:31.930" Score="23" ViewCount="4317" Body="&lt;p&gt;I'm trying to track down a story about an incident involving an Airbus airplane my father told me about 25 years ago, when he was working at a Boeing supplier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reportedly, what happened was the airplane's autopilot was set to bring them in to a certain airport, and the pilots noticed that it was descending too early.  So, they took over the controls, lined up manually, and at about a hundred feet up, the autopilot wouldn't let them descend further.  So, they did a go-around, tried the approach again, and the same thing happened.  At this point, they diverted to another airport and landed without incident.  Turned out that the airplane's database had an incorrect position for their destination: the plane thought they were overshooting the runway, and wouldn't let them perform what it saw was an off-airport landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was this based on an actual incident, or just one of the &quot;Airbus airplanes don't let the pilot fly&quot; stories circulating among Airbus competitors?&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="1677" LastEditDate="2015-04-30T22:35:59.323" LastActivityDate="2015-04-30T22:35:59.323" Title="Was there an incident when Airbus autopilot wasn't letting the airplane land?" Tags="&lt;safety&gt;&lt;autopilot&gt;&lt;airbus&gt;" AnswerCount="1" CommentCount="16" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6346" PostTypeId="2" ParentId="6345" CreationDate="2014-06-17T10:40:05.847" Score="30" Body="&lt;p&gt;I believe this is a hoax&lt;sup&gt;1&lt;/sup&gt;. I've read through several documents describing the protections provided by Airbus flight laws (this is not autopilot; autopilot is a separate layer on top of it) and have never seen any mention of any kind of ground proximity protection. Only standard (E)GPWS which yells &quot;terrain, pull up&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: Of course &lt;em&gt;now&lt;/em&gt; there is &lt;b&gt;E&lt;/b&gt;GPWS that gets aircraft position from GPS and can yell &quot;terrain, pull up&quot; when there is no airport ahead, but 25 years ago there was only GPWS based on radar altimeter which didn't know anything about position and would switch to simply read out&lt;sup&gt;2&lt;/sup&gt; the radar altimeter value whenever gear (and maybe also flaps; not sure here) was extended.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;Might have been even attempt at &lt;a href=&quot;http://en.wikipedia.org/wiki/Fear,_uncertainty_and_doubt&quot;&gt;FUD&lt;/a&gt; against the then novel technology.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;sub&gt;That is say &quot;one thousand&quot;, &quot;five hundred&quot;, &quot;two hundred&quot;, &quot;one hundred&quot;, &quot;fifty&quot;, &quot;forty&quot;, &quot;thirty&quot;, &quot;twenty&quot;, &quot;retard&quot;&lt;sup&gt;3&lt;/sup&gt; (and &quot;ten&quot; or &quot;five&quot; when it stops saying &quot;retard&quot; and the wheels are not on the ground yet). This is useful during approach so the pilot can concentrate less on the instruments and more on outside reference and in the final phase to help judge when flare should be initiated. It will also warn &quot;sink rate&quot; when the sink rate is excessive (more than -1000 ft/min, the stabilized approach criteria).&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;&lt;sub&gt;At 15 or so feet, if the thrust levers are not in idle gate, the Airbus system starts announcing &quot;retard&quot; and keeps announcing it until the thrust levers are placed in the idle gate (or reverse). This is specific to Airbus. I believe it can also announce &quot;minimums&quot; when approach minima are configured in the flight management system.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="65" LastEditDate="2015-03-12T19:01:39.947" LastActivityDate="2015-03-12T19:01:39.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6347" PostTypeId="2" ParentId="6336" CreationDate="2014-06-17T13:15:37.753" Score="9" Body="&lt;p&gt;If you've ever watched an aircraft carrier launch a plane, you'll see such a barrier pop up (on hinges) right behind the jet exhaust to deflect it upward and away from other aircraft and deck crew behind the launch catapult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These things (picture above) look pretty heavy, so they won't be blown over easily. I doubt they would use them to mark a closed runway, unless it's quite long term, as they would be difficult to move around. Does anyone know if they are in fact lightweight, and attach to the runway in some manner?&lt;/p&gt;&#xA;" OwnerUserId="1078" LastActivityDate="2014-06-17T13:15:37.753" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6348" PostTypeId="1" CreationDate="2014-06-17T15:48:13.587" Score="17" ViewCount="15179" Body="&lt;p&gt;Well, since this stack is in beta, I thought I'd take a wack at asking a book question to see how it fits in this particular community (of if it even fits to begin with).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm very curious about how aerodynamics work in plane design (especially wing design), but it's hard for me to ask questions here because I'm lack knowledge of so many of the basics.  So I wondered if I could get a recommendation on a good book to learn the basics of aerodynamics?  Keeping in mind that my understanding of math is limited, so I would need a book that explains the math being used to some extent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bear in mind when answering:  This is a Q&amp;amp;A site, so try and have some reasoning behind why your book is the best.  Especially if you could show it has good explanations of the math and, also, the books is good for the somewhat beginner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's see if this works...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="19" LastEditDate="2017-01-16T13:07:06.597" LastActivityDate="2017-01-16T13:07:06.597" Title="What are good books to learn basic aerodynamics in plane design?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;books&gt;&lt;literature-recommendation&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="11" ClosedDate="2019-09-09T11:17:56.543" CommunityOwnedDate="2014-06-17T18:59:32.073" ContentLicense="CC BY-SA 3.0" />
  <row Id="6349" PostTypeId="2" ParentId="6326" CreationDate="2014-06-17T15:59:57.987" Score="4" Body="&lt;p&gt;The latest revision of the MMEL for the A320 family was approved a month ago by EASA. The &lt;a href=&quot;https://easa.europa.eu/document-library/master-minimum-equipment-lists?search=airbus&amp;amp;date_filter%5Bmin%5D%5Bdate%5D=&amp;amp;date_filter%5Bmax%5D%5Bdate%5D=&amp;amp;field_easa_supplement_value=All&quot; rel=&quot;nofollow&quot;&gt;EASA website&lt;/a&gt; only contains a PDF document with the &lt;a href=&quot;https://easa.europa.eu/document-library/master-minimum-equipment-lists/airbus-a318a319a320a321&quot; rel=&quot;nofollow&quot;&gt;MMEL approval signature&lt;/a&gt; for Airbus aircraft.  For some manufacturers (e.g. Cessna) the full MMEL is included on the EASA website. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://easa.europa.eu/master-minimum-equipment-lists-information&quot; rel=&quot;nofollow&quot;&gt;information page&lt;/a&gt; on MMELs says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each MMEL document is the property of the (S)TC holder, and only made&#xA;  available here in full if requested by the (S)TC holder. If a full&#xA;  copy is not available here then please contact the (S)TC Holder to get&#xA;  a copy of the document in question.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you have to contact Airbus in this case. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-06-17T15:59:57.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6350" PostTypeId="2" ParentId="6348" CreationDate="2014-06-17T16:17:53.633" Score="13" Body="&lt;h2&gt;Beginner&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0073398101&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Fundamentals of Aerodynamics&lt;/strong&gt;&lt;/a&gt; by John D. Anderson, Jr.&lt;br&gt;&#xA;Introduces the basics of aerodynamics with historical background, the mathematical explanation and some practical applications. In the latest edition,  Computational Fluid Dynamics is also discussed. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0470539755&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Mechanics Of Flight&lt;/strong&gt;&lt;/a&gt; by Warren F. Phillips.&lt;br&gt;&#xA;Anderson's book is a good text for understanding the building blocks of fluid dynamics, such as the different types of flow. It is good for understanding how airfoils and wings work, as well as understanding the microscopic flow considerations. Phillips' text also talks plenty about flight dynamics and control, so you can better picture the forces acting on an airplane.&lt;br&gt;&#xA;Anderson's and Phillips' make a very good learning pack.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Intermediate&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;No books found as of yet&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Advanced&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/9998831636&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Fluid Dynamic Lift&lt;/strong&gt;&lt;/a&gt; &amp;amp; &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/9991194444&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Fluid Dynamic Drag&lt;/strong&gt;&lt;/a&gt; both by Hoerner&lt;br&gt;&#xA;I wouldn't consider these to be great &quot;learning&quot; textbooks, and the math can get very intensive at times, but these are still go-to reference text, and they are a great resource if you want to start a &quot;deep dive&quot; into aerodynamics and the practical effects of various design decisions. Both books are replete with wind-tunnel testing information and diagrams, as well as the supporting equations to back it all up.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Classics / Older&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/156027140X&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Aerodynamics for Naval Aviators&lt;/strong&gt;&lt;/a&gt; by H. H. Hurt Jr.&lt;br&gt;&#xA;This is a good primer on basic aerodynamics - as the title implies it's primarily aimed at naval aviators, but the material is pretty accessible and much of it is applicable to all fixed-wing aviation. There's even some helicopter stuff in there, though the section is rather thin.&lt;br&gt;&#xA;This book is available from a number of publishers. It is also known as &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80T-80.pdf&quot; rel=&quot;nofollow&quot;&gt;NAVAIR 00-80T-80 or NAVWEPS 00-80T-80&lt;/a&gt; and available from the FAA in PDF form.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Additional references&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As far as mathematics goes, you can get &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/053439339X&quot; rel=&quot;nofollow&quot;&gt;Stewart's Calculus&lt;/a&gt; text. It is a pretty good book with quite satisfactory explanations, and you can get an older edition for almost nothing (make sure you get the full text with both single variable calculus and multivariable calculus sections). Without a basic understanding of calculus it will be difficult for you to get a good grasp of the aerodynamics material.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="65" LastEditDate="2014-11-24T20:41:27.047" LastActivityDate="2014-11-24T20:41:27.047" CommentCount="1" CommunityOwnedDate="2014-06-17T18:59:32.073" ContentLicense="CC BY-SA 3.0" />
  <row Id="6351" PostTypeId="2" ParentId="6348" CreationDate="2014-06-17T16:32:52.550" Score="5" Body="&lt;p&gt;I'm with DeltaLima's &lt;a href=&quot;http://eng.sut.ac.th/me/box/1_54/437310/%5BAnderson%5D%20FUNDAMENTALS_OF_AERODYNAMIC.PDF&quot;&gt;book recommendation&lt;/a&gt; [pdf]. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, this chapter of a larger ebook covers some basic aerodynamics: &lt;a href=&quot;http://www.av8n.com/how/htm/airfoils.html&quot;&gt;http://www.av8n.com/how/htm/airfoils.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2014-06-17T16:32:52.550" CommentCount="1" CommunityOwnedDate="2014-06-17T18:59:32.073" ContentLicense="CC BY-SA 3.0" />
  <row Id="6352" PostTypeId="2" ParentId="6320" CreationDate="2014-06-17T21:02:46.117" Score="6" Body="&lt;p&gt;You can read about some guidance from the FAA about HUD design in these two Advisory Circulars:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1311-1C.pdf&quot;&gt;General electronic displays&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2090-106.pdf&quot;&gt;Enhanced Flight Vision Systems&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_4.pdf&quot;&gt;This handbook&lt;/a&gt; is a bit dated but covers certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It really depends on what exactly the HUD is supposed to do. Any pilot can bring a handheld GPS along, with the understanding that it is not an &quot;official&quot; navigation instrument. A HUD could be used in a similar way. There are a couple things to keep in mind:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the HUD is to be used for real navigation or pilot reference, then certification will be an issue. The handbook above talks about this. The HUD would need to be certified just like any other instruments in the cockpit for that use. If a HUD is used for special situations, like low visibility landing, it must be certified in order to be used in those situations. Otherwise you are not allowed to do anything you could not do without the HUD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the HUD is not to be used for critical flight data, the HUD needs to comply with the FAR 25 sections 25.773 and 25.775, which talk about the windows in the cockpit. The HUD can't interfere with the normal visibility the pilot should have.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-17T21:02:46.117" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6353" PostTypeId="2" ParentId="6319" CreationDate="2014-06-17T21:19:48.217" Score="10" Body="&lt;p&gt;There are probably two main factors that come into play with the placement of the wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Height of fuselage from ground&lt;/strong&gt;&lt;br/&gt;&#xA;Especially for military airlifts, the ability to load cargo is extremely important. They need to be able to load large objects and vehicles, and with little or no ground support available. This means that the fuselage should be as close to the ground as possible to allow roll-on/roll-off of cargo with built-in ramps. Placing the wings on top of the fuselage allows the bottom of the fuselage to be closer to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is less of a problem for airlines. Commercial cargo can usually count on ground equipment for loading and unloading cargo containers on aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Ease of maintenance&lt;/strong&gt;&lt;br/&gt;&#xA;Since airliners don't need easy access to the fuselage to load cargo, maintenance should be as simple as possible. Especialy with the larger aircraft like the C-5, a high-wing puts the engines and wings far above the ground. This makes it much more difficult to work on these components. Keeping the wings and engines low to the ground makes it much easier to replace an engine or access the wings, such as for refueling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The military wants planes to be easy to maintain as well, but they are willing to make some tradeoffs for the better cargo loading configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are of course many other tradeoffs in areas like structure and stability. However, it's clear that both configurations are perfectly feasible. The most important factors come down to the usability of the design.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-17T21:19:48.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6354" PostTypeId="2" ParentId="6325" CreationDate="2014-06-17T21:42:37.243" Score="2" Body="&lt;p&gt;As Jan Hudec mentioned, advances in computing mean that off-the-shelf commercial processors offer plenty of computing power for use in UAVs or other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at a couple of examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Rockwell Collins &lt;a href=&quot;https://www.rockwellcollins.com/~/media/Files/Unsecure/Products/Product%20Brochures/Computing/Processing%20Mission%20Computers/IPC%208303%20data%20sheet.aspx&quot; rel=&quot;nofollow&quot;&gt;IPC-8303&lt;/a&gt; computer uses an Intel Pentium-M 738 at 1.4 GHz, 2 MB L2 cache, 10 watts. There is also a PowerPC option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Rockwell Collins &lt;a href=&quot;https://www.rockwellcollins.com/~/media/Files/Unsecure/Products/Product%20Brochures/Navigation%20and%20Guidance/Flight%20Management%20Systems/FMC-4000/FMC-4000%20brochure.aspx&quot; rel=&quot;nofollow&quot;&gt;FMC-4000&lt;/a&gt; mission computer is able to accommodate a variety of processors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Quad core PPC 1.5 GHz&lt;/li&gt;&#xA;&lt;li&gt;Dual core PPC 1.3 GHz&lt;/li&gt;&#xA;&lt;li&gt;Single core PPC 7448 1.3 GHz&lt;/li&gt;&#xA;&lt;li&gt;Single core PPC 8315E 600 MHz&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;They also mention that other components such as Intel Atoms or i7 Dual/Quad core processors can be added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of information processed by these computers has increased along with their power. The FMC-4000 can use a 10-gigabit uplink. Modern computers are designed to process all kinds of sensor data. For aircraft like the MQ-1 or especially the RQ-4, there are many sensors, including video data, feeding into these computers. They are capable of much more than the first flight computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also mentioned by Jan Hudec, the key in aerospace systems is redundancy. Each subsystem is generally controlled by multiple computers. This ensures both accuracy and reliability, and prevents the whole system from going down due to one computer failing.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-17T21:42:37.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6355" PostTypeId="1" CreationDate="2014-06-17T23:09:26.510" Score="20" ViewCount="10037" Body="&lt;p&gt;I am a combat veteran who was diagnosed with moderate &lt;a href=&quot;http://en.wikipedia.org/wiki/Posttraumatic_stress_disorder&quot;&gt;Posttraumatic stress disorder (PTSD)&lt;/a&gt; after getting out last year. I  decided to seek treatment and, upon reevaluation, am now at a very mild rating for PTSD with no personality disorders, and no use of medications ever. I am not even eligible for disability compensation that is how NOT severe my PTSD is or ever was. I am currently in the process of trying to get my FAA Medical Certificate for a student pilot and the FAA came back wanting these extreme and expensive tests that were never conducted by my psychologist because they were deemed unnecessary. My psychologist is writing the report they requested, but I have a feeling they will dismiss it and cancel/deny my application because I only have my medical records and my psychological report and cannot afford the psychiatric evaluations and the VA cannot do them for me because they are not medically needed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to my question, if they deny it, then I will reapply again, however as I am as close to 'cured' as possible when it comes to PTSD and it does not affect my reactions to stressful situations or anything that could come up in flying (I've been in a helicopter during the healing process so I know), do I just NOT put anything in the mental disorders box? And if so will they hit me back with &quot;hey we know you applied last time with this, so you're a liar&quot;? PTSD is a curable thing and I feel even more normal than before I even joined the military. Thanks for your time.&lt;/p&gt;&#xA;" OwnerUserId="2635" LastEditorUserId="65" LastEditDate="2015-02-26T17:55:59.753" LastActivityDate="2017-04-08T16:50:28.643" Title="Should I report my cured mild PTSD in the FAA medical certification application?" Tags="&lt;military&gt;&lt;medical&gt;&lt;student-pilot&gt;&lt;faa-approval&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6358" PostTypeId="2" ParentId="6355" CreationDate="2014-06-18T01:42:17.550" Score="10" Body="&lt;p&gt;This is one of those cases where your instructor should have encouraged you to talk to an FAA medical certification expert before you talk to an AME (something like &lt;a href=&quot;http://pilot-protection-services.aopa.org&quot;&gt;AOPA's &quot;Pilot Protection Services&quot;&lt;/a&gt;) so they can help you get everything in order.  You've already talked to an AME, but you can still use those same resources to help you deal with their bureaucratic hurdles now that you're in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gist of the situation is is &quot;You probably need to get a Special Issuance medical&quot;, which means you'll need to supply a bunch of supporting documentation to the FAA. AOPA's folks can work with you, your psychologist/psychiatrist, and your AME to help cut through the FAA red tape. This was talked about in the &quot;Ask Medical Certification&quot; section of &lt;a href=&quot;http://www.faa.gov/news/safety_briefing/2012/media/JanFeb2012.pdf&quot;&gt;FAA Safety Briefing in January 2012&lt;/a&gt;, though not in any great depth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The good news is none of this has to really hobble your training: You're just chained to your instructor until you can browbeat the FAA into issuing you a medical (and in the worst case it sounds like that's just a matter of money to get the tests the FAA wants done - as with all things aviation, money is what makes it go).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To the second part of your question: anything you report to the FAA in your medical application is &quot;on the record&quot;: You can't just leave the box blank on your next application, because eventually there will be a red flag (and &quot;eventually&quot; tends to be right away now that all the medical stuff is processed electronically).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that if you are &lt;em&gt;denied&lt;/em&gt; a medical certificate (or have one revoked) you need to jump through the hoops to get a valid medical issued in order to fly. (Unfortunately this includes Sport Pilot privileges: you cannot self-certify under the &quot;Driver's License Medical&quot; if you've had your most recent FAA medical application denied. Once you've got a valid medical though you can let it expire and exercise Sport Pilot privileges, and my understanding is that holds even if it was a Special Issuance medical.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-18T01:42:17.550" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6359" PostTypeId="2" ParentId="6355" CreationDate="2014-06-18T01:58:53.583" Score="14" Body="&lt;p&gt;Unfortunately, you have to report it.  It even says so right on the medical application (emphasis added by me):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;18) Medical History - HAVE YOU &lt;strong&gt;EVER IN YOUR LIFE BEEN DIAGNOSED WITH, HAD, OR DO YOU PRESENTLY HAVE&lt;/strong&gt; ANY OF THE FOLLOWING? Answer&#xA;  &quot;yes&quot; or &quot;no&quot; for every condition listed below (All &quot;yes&quot; answers&#xA;  require a comment. Click Add Comments to add or edit a comment).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Mental disorders of any sort: depression, anxiety, etc.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on your own admission, you had it at one point and are now cured.  This means that you have &quot;at some point in your life&quot; been diagnosed with it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the FAA takes a very hard line on this kind of thing and it does not surprise me in the least that they are now requiring a battery of expensive tests in order to prove that you are fit to fly.  I don't like it either, but it does keep the people out who &quot;say&quot; that they are cured when they aren't, either because they don't realize it or because they just want to fly anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is denied, then you can appeal it, but I would suggest getting good professional help.  As voretaq7 mentioned, AOPA has a very good medical service that helps their members for free.  Membership is pretty inexpensive, and more than worth it just for this service, plus they have many many other benefits as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple of other questions on the site that may help you:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1747/69&quot;&gt;FAA Class 3 Medical re-examination&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2250/69&quot;&gt;Can a private pilot receive recurring training while waiting for a special-issuance medical approval?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-06-18T02:18:35.500" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6360" PostTypeId="2" ParentId="6355" CreationDate="2014-06-18T02:11:37.337" Score="9" Body="&lt;p&gt;Never lie on the medical forms.  It can only come back go bite you after you have spent thousands on your certificates.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need the advice of a specialist in difficult aviation medical certifications.  Some may disagree, but in my mind the very best is Doctor Bruce Chien, Peoria IL.  See the following web page:  &lt;a href=&quot;http://www.aeromedicaldoc.com/&quot; rel=&quot;nofollow&quot;&gt;http://www.aeromedicaldoc.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do exactly as he says.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may want to browse the Medical Matters forum on the AOPA website, www.aopa.org  to get a flavor of what he does and how many he has helped.  If anyone can guide you to a successful medical certification, it is Dr. Bruce.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recall, however, that unfortunately not everyone is eligible.  If your case is other than routine (and it sounds like yours is) DO NOT SEEK a medical certification without his assistance.  You said you are seeking a psych evaluation.  Did you know that the report must contain certain magic phrases? That certain MDs are held in higher respect by the FAA? Your case needs a strong advocate....&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="162" LastEditDate="2015-11-04T00:34:12.567" LastActivityDate="2015-11-04T00:34:12.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6361" PostTypeId="1" AcceptedAnswerId="6362" CreationDate="2014-06-18T13:22:19.833" Score="31" ViewCount="23898" Body="&lt;p&gt;One thing I noticed with the A380 is that it only seems to use the inboard thrust reversers while landing. I suspect it relates to FOD ingestion or perhaps damaging the runway. This is strange though, because the 747-8 (which also has a large wingspan and very large engines), &lt;em&gt;does&lt;/em&gt; use all of its thrust reversers during landing. Does anyone have an official answer on why this is?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TOLH3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XDSuq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bRGI4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2473" LastEditorUserId="1467" LastEditDate="2014-06-18T13:36:52.183" LastActivityDate="2017-04-25T19:29:06.247" Title="Why doesn't the A380 use its outboard thrust reversers?" Tags="&lt;landing&gt;&lt;runways&gt;&lt;thrust-reverser&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6362" PostTypeId="2" ParentId="6361" CreationDate="2014-06-18T13:36:51.970" Score="29" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why doesn't the A380 use its outboard thrust reversers?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because it doesn't have (or need) any.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A380 has reverse thrust on the inboard engines only. This saves weight and since the outboards are often way out over the edge of runways, decreases the risk of FOD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;From &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/283197/&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like all certified transport aircraft of this type, the A380 can stop from V1 on brakes alone with disks worn to minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/160631/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mA4Cg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read that most airliners are allowed to take off even when all reverse-thrusters are inoperative. Most of the deceleration is handled by the brakes normally.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With the Airbus A380 weighing in fully loaded at 1,265,000 pounds, you might think stopping it within a reasonable distance after landing would require a Phalanx of Heavy-duty thrust reversers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Truth be told, in the megaliner’s braking system, thrust reversers are the least critical components. Airliners are not required to have thrust reversers, and only the two inboard engines on the A380 are equipped with them. The decision not to install reversers on the A380’s two outboard engines saved weight and lowered the chances that those engines, which sometimes hang over runway edges, would be damaged by ingesting foreign objects.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;From &lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-stopping-the-a380-27549065/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;Airspace Magazine&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;More details of &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-Jan16.pdf&quot; rel=&quot;noreferrer&quot;&gt;braking system&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.&#xA;   General&lt;br&gt;&#xA;   The aircraft has:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Two Wing Landing Gears (WLG) with four wheel bogie assembly and related doors&lt;/li&gt;&#xA;  &lt;li&gt;Two Body Landing Gears (BLG) with six wheel bogie assembly and related doors&lt;/li&gt;&#xA;  &lt;li&gt;A Nose Landing Gear (NLG) with twin wheel assembly and related doors.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;7&quot;&gt;&#xA;  &lt;li&gt;&lt;p&gt;Braking&lt;br&gt;&#xA;  A.    General&lt;br&gt;&#xA;  Carbon brakes are installed on each wheel of the WLG and on the wheels of the front and center axles of the BLG.&lt;br&gt;&#xA;  The braking system is electrically controlled and hydraulically operated.&lt;br&gt;&#xA;  The braking system has four braking modes plus autobrake and anti-skid systems:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Normal braking with anti-skid capability&lt;/li&gt;&#xA;  &lt;li&gt;Alternative braking with anti-skid capability&lt;/li&gt;&#xA;  &lt;li&gt;Emergency Braking (with Ultimate Braking)&lt;/li&gt;&#xA;  &lt;li&gt;Emergency braking without anti-skid protection is also available as an alternative function of the alternate braking system.&lt;/li&gt;&#xA;  &lt;li&gt;A park brake system that is manually set is available for the BLG only. This system can also be used to supply emergency braking.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ieL8i.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ieL8i.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/RdCGW.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RdCGW.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;FOD risk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i5RVw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i5RVw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.berrymanenvironmental.co.uk/case-studies/runway-improvement&quot; rel=&quot;noreferrer&quot;&gt;A380 Landing at Farnborough Airport&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;A380 vs 747&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The design of the A380’s wings, with their large area, comparatively gentle sweep (33.5 degrees), and massive flaps, give the Airbus a landing speed that is 20 knots slower than that of a 747. An A380 crosses the landing threshold at a docile 140 knots and touches down, depending on its landing weight, at a speed as slow as 130 knots, about the same touchdown speed of some corporate jets that weigh 1/50th as much as the world’s biggest airliner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-stopping-the-a380-27549065/&quot; rel=&quot;noreferrer&quot;&gt;AirspaceMag&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-12-15T17:18:43.323" LastActivityDate="2016-12-15T17:18:43.323" CommentCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="6363" PostTypeId="2" ParentId="1189" CreationDate="2014-06-18T14:05:44.203" Score="1" Body="&lt;p&gt;This may be a dead thread, but I wanted to interject something my CFI taught me. He also instructed me to raise flaps right after touch-down in a 172, his reason being this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a high wing plane, full flaps divert air flow from the empennage and elevator. If you have the elevator deflected all the way up (yoke back), it creates much more drag then full flaps because of the way the air travels around the plane. If you have flaps down, your are getting some aerodynamic braking, but not nearly as much as you would if you clean up the flaps and hold the yoke back.&lt;/p&gt;&#xA;" OwnerUserId="2638" LastActivityDate="2014-06-18T14:05:44.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6364" PostTypeId="2" ParentId="6355" CreationDate="2014-06-18T15:18:24.970" Score="0" Body="&lt;p&gt;You might want to look into the Sport Pilot certificate.  There are more restrictions on flying than with a Private certificate, but at least you can fly.  You do not need to get an FAA medical certificate, although there are some caveats.  Your descriptions indicates that you'd qualify.  You must have a valid U.S. driver's license.  FAA has a great brochure on the program that does not read like your typical gov't snooze-fest.  Search for &quot;sport pilot&quot; and you'll easily find it.  FWIW - I hold a private pilot certificate and have been most recently flying under sport pilot rules without a medical.&lt;/p&gt;&#xA;" OwnerUserId="2639" LastActivityDate="2014-06-18T15:18:24.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6365" PostTypeId="2" ParentId="5019" CreationDate="2014-06-18T15:26:43.133" Score="20" Body="&lt;p&gt;You have asked several questions. I'll try to answer them in order to clarify.&lt;/p&gt;&#xA;&lt;h3&gt;Is the ferry range specified anywhere?&lt;/h3&gt;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.airbus.com/support-services/support/technical-data/aircraft-characteristics/&quot; rel=&quot;noreferrer&quot;&gt;Airbus website&lt;/a&gt;, we find for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Engine_Alliance_GP7000&quot; rel=&quot;noreferrer&quot;&gt;Engine Alliance GP7000&lt;/a&gt; engine option the ferry range is ~9,600 NM. Let's just say it's 9,500 NM.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A:&lt;/strong&gt; 9,500 NM. Also, waiting for the right trade winds can &lt;a href=&quot;https://aviation.stackexchange.com/a/33350&quot;&gt;increase you range&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Can an A380 fly between any two airports on Earth?&lt;/h3&gt;&#xA;&lt;p&gt;If you place the originating marker over Dubai, UAE, then the A380-800 can fly to any airport on Earth except a region in South Pacific Ocean. This area (a circle of around 6500 km diameter) has many small island states (French Polynesia, Cook Island, American Samoa etc.).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/v5Bi5.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/v5Bi5.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;BR&gt;(gcmap.com)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A:&lt;/strong&gt; Yes, probably over 99% of airports.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Has a flight by an A380 in excess of 15,700 km been performed to date?&lt;/h3&gt;&#xA;&lt;p&gt;None that I could find. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Non-stop_flight#Currently_scheduled_.28top_30.2C_by_distance.29&quot; rel=&quot;noreferrer&quot;&gt;longest flight of A380&lt;/a&gt; (currently) is &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_7&quot; rel=&quot;noreferrer&quot;&gt;QF 8&lt;/a&gt; (with duration 16:50 hours).&lt;/p&gt;&#xA;&lt;p&gt;We know that A380 (October 25, 2007&lt;sup&gt;1&lt;/sup&gt;) is much newer than 777 (June 7, 1995&lt;sup&gt;2&lt;/sup&gt;) and 747 (January 22, 1970&lt;sup&gt;3&lt;/sup&gt;). In future, there can be attempts to fly it in excess of 15,700 km.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A:&lt;/strong&gt; No record so far.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;What is the ferry range of an A380?&lt;/h3&gt;&#xA;&lt;p&gt;This was your original question. Most of the flights mentioned on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_distance_record#Commercial_aircraft&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia article&lt;/a&gt; you referred to were either delivery flights or for demonstration purposes. For such flights, you can have:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;lesser people on board&lt;/li&gt;&#xA;&lt;li&gt;lesser equipment (seats etc.) so more space to add extra fuel tanks&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;With the above two changes, the result would be:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less people = Less weight. The aircraft will weigh less and its range can increase.&lt;/li&gt;&#xA;&lt;li&gt;Less seats = Less weight. The aircraft will weigh less and its range can increase.&lt;/li&gt;&#xA;&lt;li&gt;More space to add fuel tanks. The aircraft's range will increase.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In addition, A380-800 has &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Specifications&quot; rel=&quot;noreferrer&quot;&gt;cargo volume&lt;/a&gt; of 6500 cubic feet. If we have a hypothetical rubber tank which fills all this space, we can add 184,000+ L of additional fuel than the original capacity of 323,546 L. This can increase the range over 50%.&lt;/p&gt;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.turtlepac.com/photo-gallery/aircraft-ferry-tanks/&quot; rel=&quot;noreferrer&quot;&gt;website&lt;/a&gt; contains pictures of additional fuel tanks. As you can see, those are inflatable and can adjust to the space available.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A:&lt;/strong&gt; It depends.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1: Introduction with Singapore Airlines&lt;/sup&gt;&lt;br/&gt;&#xA;&lt;sup&gt;2: Introduction with United Airlines&lt;/sup&gt;&lt;br/&gt;&#xA;&lt;sup&gt;3: Introduction with Pan American World Airways&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-02-15T18:12:45.830" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="6366" PostTypeId="1" AcceptedAnswerId="6368" CreationDate="2014-06-18T15:27:48.497" Score="31" ViewCount="8116" Body="&lt;p&gt;The &lt;strong&gt;direct&lt;/strong&gt; cause of stall is unclear to me.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I heard about exceeding maximum &lt;strong&gt;angle of attack&lt;/strong&gt; (around 40°) ;&lt;/li&gt;&#xA;&lt;li&gt;I heard about reaching the stall &lt;strong&gt;speed&lt;/strong&gt; in the current configuration (flaps, etc).&lt;/li&gt;&#xA;&lt;li&gt;I heard about load factor which can lead to a stall.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are these three parameters both &lt;em&gt;direct&lt;/em&gt; causes of stall?&lt;/strong&gt; By &quot;direct&quot;, I mean for example that pitch is not a direct cause to stall, since pitch let AoA vary which causes stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's unclear because there is a relation between angle of attack and speed. When we increase the angle of attack, we lower speed. But at the end, what will be the cause of stall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If both causes are direct causes, are they independent?&lt;/strong&gt;&#xA;- It should be possible to fly very fast (faster than stall speed) and have an angle of attack of 40°.&#xA;- It should also possible to have a very low speed (lower than stall speed) and have an angle of attack which produces lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What parameter will win and how are they related together?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aircraft is on the ground, taxiing at 10kt, the speed alone makes the plane stall, regardless of the angle of attack, am I right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I would like to know necessary conditions to stall, and sufficient conditions to stall (all conditions being direct causes).&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2452" LastActivityDate="2019-03-27T21:38:54.363" Title="What is the immediate cause of stall?" Tags="&lt;stall&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6367" PostTypeId="2" ParentId="6366" CreationDate="2014-06-18T15:51:55.237" Score="10" Body="&lt;p&gt;&lt;strong&gt;Stall&lt;/strong&gt; means that the wing has exceeded its critical angle of attack. Nothing more, nothing less. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to fly very fast beyond critical angle? Sure. &lt;strike&gt;Look up Pugaychev's Cobra. Or look at the Saturn V rocket. Both aircraft are stalled, yet they continue to fly.&lt;/strike&gt; My previous example was flawed, but the sentiment stands.  Put enough thrust behind a brick outhouse and you can get it to fly. (Thanks newmanth!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about flying slowly beyond stall? That won't work; beyond critical angle you develop less lift the more you increase AoA. For any given airspeed / wing / air density configuration, there is some maximum lift value which cannot be exceeded. So the more slowly you fly, the more down you go. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your example of an aircraft taxiing at 10kt is an excellent one. Just because the airplane is moving slowly does not mean that the wing is stalled. There is 10kt of relative wind passing over the wing, and the angle of attack is close to 0. The wing isn't stalled, it's just not generating enough lift to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To reiterate, &lt;strong&gt;stall means that the wing has exceeded its critical angle of attack&lt;/strong&gt;. That's it. &lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2014-06-19T02:45:32.667" LastActivityDate="2014-06-19T02:45:32.667" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6368" PostTypeId="2" ParentId="6366" CreationDate="2014-06-18T15:57:09.937" Score="32" Body="&lt;p&gt;The &lt;strong&gt;immediate&lt;/strong&gt; cause of a stall is the detachement of the airflow from the wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ySQhv.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/inclind.html&quot;&gt;NASA&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This happens when your Angle of Attack is too high.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How can the AoA become too high?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;--For level flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Given a certain velocity, you will have a certain AoA that will provide the lift needed for level flight. The lower the velocity, the higher this AoA.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Given a certain wing (configuration) you will have a certain maximum allowed AoA (in the picture is the AoA for wich you have the highest value of the plot):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UOOBX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;http://en.wikipedia.org/wiki/Angle_of_attack&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given these two tidbits of information, you can see what is the answer to your question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the velocity is too low, to fly straight you need an AoA that exceeds the capabilities of your wings (or a vectorial thrust that exceeds the weight of your veichle, but I would say that it is not quite common)&lt;/li&gt;&#xA;&lt;li&gt;If the AoA is too high, well, is quite evident that you have stalled.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;--For curved flight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a turn you need to use a component of your lift vector to actually turn&#xA;&lt;img src=&quot;https://i.stack.imgur.com/PCa2E.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;http://tommywiklind.com/aviation/TurningFlight.html&quot;&gt;here&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see the lift you need to turn is larger that the lift you need to fly level (given the same speed). And to have a higher lift you need a higher AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And once again back to the AoA we are: if you want to turn too much (high load factor) you need a lot of extra lift, meaning that you have to increase your AoA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you exceed your wing limits, you stall&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dynamic stall&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not exactly my cup of tea, but reading from the already linked wikipedia article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dynamic stall is a non-linear unsteady aerodynamic effect that occurs when airfoils rapidly change the angle of attack. The rapid change can cause a strong vortex to be shed from the leading edge of the aerofoil, and travel backwards above the wing. The vortex, containing high-velocity airflows, briefly increases the lift produced by the wing. As soon as it passes behind the trailing edge, however, the lift reduces dramatically, and the wing is in normal stall.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would say that once again we fall in the &quot;too big AoA&quot; case, even if for different causes.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-06-18T16:26:41.293" LastActivityDate="2014-06-18T16:26:41.293" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="6369" PostTypeId="2" ParentId="2381" CreationDate="2014-06-18T17:11:24.060" Score="11" Body="&lt;p&gt;Fighter aircraft routinely fly close to give a false indication of numbers (I used to do it), but close formation is rarely necessary.&#xA;The basic resolution angle formula for a radar is 1.22*wavelength/diameter = angular resolution in radians (circular antenna).&#xA;For long range Air Traffic Control, typical wavelength is 0.15m, diameter of aerial is 14m. So at 60nm this gives a distance resolution of about 3/4 of a mile. Real antenna have various physical and electronic devices to improve this, so in practice staying at less than 1/10 of this, say 150m, usually means no detection. 150m is the standard FAA specification for its long range radars. We used to use about 75m since we liked to stay &quot;numbers disguised' till about 30nm range.&#xA;The real problem for the pilot of MH370 would be that he has very little overtake available to effect the intercept, or a suitable Air Interception radar, which makes it highly unlikely he could have achieved it, as he had no fighter background.&#xA;There used to be a prohibition on HF radio ops during aerial refueling but I believe this was for static electric reasons rather than transmission interference. Flying in close formation (5m or less separation) can cause buffeting effects, but basically a plane 75m away is not going to give any indication it's there.&#xA;Formation flying is not easy, especially in an airliner!&lt;/p&gt;&#xA;" OwnerUserId="2640" LastEditorUserId="2640" LastEditDate="2014-06-18T17:21:02.590" LastActivityDate="2014-06-18T17:21:02.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6372" PostTypeId="1" AcceptedAnswerId="6374" CreationDate="2014-06-18T19:38:03.093" Score="9" ViewCount="15942" Body="&lt;p&gt;With the success of &lt;a href=&quot;https://aviation.stackexchange.com/questions/6348/good-book-to-learn-basic-aerodynamics-in-plane-design/6371#6371&quot;&gt;this question&lt;/a&gt;, which asks about good books on aerodynamics, I thought I'd ask another general question regarding books that we can turn into a community wiki.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are good books to use to learn how to fly?  And yes, I know that, in the end, you'll just need a good instructor.  But there are several books that suppliment a good instructor, or can be used by people who are interested in learning to fly, but perhaps are unable to get an instructor just yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; I am well aware this is a very general question.  But I would like to have a centralized resource, vetted by users of this stack, that we can point to when someone asks for text resources on learning how to fly.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-06-18T20:30:54.870" Title="Book recommendations for learning how to fly?" Tags="&lt;flight-training&gt;&lt;books&gt;&lt;literature-recommendation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="7" ClosedDate="2019-09-09T11:17:44.917" CommunityOwnedDate="2014-06-18T19:53:01.290" ContentLicense="CC BY-SA 3.0" />
  <row Id="6373" PostTypeId="2" ParentId="1189" CreationDate="2014-06-18T19:53:18.770" Score="1" Body="&lt;p&gt;Raising the flaps while still on the runway is definitely grounds for getting at least a 'talking to' by the examiner :-( No pink slip but bad aftertaste especially when the checkride is in the bag otherwise.&lt;/p&gt;&#xA;" OwnerUserId="2167" LastActivityDate="2014-06-18T19:53:18.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6374" PostTypeId="2" ParentId="6372" CreationDate="2014-06-18T20:24:50.937" Score="7" Body="&lt;p&gt;As you pointed out in your question, no book is a substitute for actual instruction in an aircraft with a flight instructor. That being said, doing your homework and knowing what your instructor is going to expect goes a long way toward completing your training in a timely manner.&lt;br&gt;&#xA;The books here are all great reference texts to be combined with a flight instruction curriculum.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;FAA Publications / Books for initial training&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A surprising number of new student pilots are not aware of the wealth of information the FAA has compiled and published to help people learn to fly. There is a whole series of &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/&quot;&gt;FAA Handbooks and Manuals&lt;/a&gt; that you can take advantage of which are available from the FAA as well as from a variety of publishers like &lt;a href=&quot;http://www.asa2fly.com&quot;&gt;ASA&lt;/a&gt;. While all of the regulatory information is geared toward US/FAA regulations much of the technique information, signs &amp;amp; markings, etc. will be universal, in conformance with ICAO rules.&lt;br&gt;&#xA;I list a whole bunch of them here, but you can find a wealth of information by googling what you want to do and the words &quot;FAA Handbook&quot;.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Books on Flying the aircraft&lt;/strong&gt; - maneuvers, etc.&lt;br&gt;&#xA;Quite simply if it flies the FAA probably has a book about how you should fly it.  These books cover basic flying technique and the maneuvers the FAA expects pilots to be able to demonstrate.&lt;br&gt;&#xA;The popular ones include:&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/&quot;&gt;The Airplane Flying Handbook&lt;/a&gt; (FAA-H-8083-3A)&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/&quot;&gt;The Helicopter Flying Handbook&lt;/a&gt; (FAA-H-8083-21A)&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/glider_handbook/&quot;&gt;The Glider Flying Handbook&lt;/a&gt; (FAA-H-8083-13A)&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/FAA-H-8083-11.pdf&quot;&gt;The Balloon Flying Handbook&lt;/a&gt; (FAA-H-8083-11A)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Books on &quot;essential aviation knowledge&quot;&lt;/strong&gt; - Airport signs &amp;amp; markings, &quot;rules of the air&quot;, etc.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot;&gt;The Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; (FAA-H-8083-25A) is the starting point here.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/AIM/Index.htm&quot;&gt;The Aeronautical Information Manual (AIM)&lt;/a&gt; is another key resource (you will often find this as a combined &quot;FAR/AIM&quot; printed publication).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Books for the more advanced stuff&lt;/strong&gt; - Instrument ratings and beyond&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot;&gt;The Instrument Flying Handbook&lt;/a&gt; (FAA-H-8083-15B) and &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot;&gt;Instrument Procedures Handbook&lt;/a&gt; (FAA-H-8083-16) are excellent references for pilots pursuing an instrument rating.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-18T20:24:50.937" CommentCount="1" CommunityOwnedDate="2014-06-18T20:24:50.937" ContentLicense="CC BY-SA 3.0" />
  <row Id="6375" PostTypeId="2" ParentId="6366" CreationDate="2014-06-18T21:07:02.790" Score="18" Body="&lt;p&gt;There is not much to add to the two good answers, but I'll try to refine them. The main reason for a stall is &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; and, accordingly, lift loss beyond the angle of attack of maximum lift. Unfortunately, this is not a fixed number, but it depends on a range of parameters. The three most important ones are Reynolds number, rate of pitch increase and Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Reynolds number characterizes the ratio of inertial and viscous forces in a fluid. In other words, friction has more influence on airflow at lower speeds and smaller dimensions. Friction is the main reason for &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; (please read the linked article to get an explanation), and the slower the wing moves through air, the smaller the stall angle of attack is. In a taildragger taxiing at 10 knots, the wing is certainly stalled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight you need to factor in how much lift you demand from the wing. This is determined by the product of aircraft mass and load factor. If you fly a parabola with zero g, you need no lift, and the aircraft's wing will not stall at any speed. Note, however, that the elevator might need to create substantial lift in order to keep the wing close to it's zero-lift angle of attack, so the elevator might stall at low speed. You will notice when this happens, because your parabola will come to a sudden end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other end, flying a steep turn might cause a stall even at high speed, if you pull too many gs for the given speed. This is just the same as a stall in level flight at low speed. Due to Reynolds number effects, the stall angle of attack might be a few degrees higher, but details depend on the particular aircraft and it's airfoils. Generally, your stall speed in a turn goes up with the inverse of the square root of the cosine of the bank angle. In a 60° turn, your stall speed is 1.41 of your level stall speed, and at 75° it will be almost double your level stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pitch rate can have a dramatic, but short-lived influence. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/stalling-at-any-speed/3620#3620&quot;&gt;this post&lt;/a&gt; for details. In tests, the maximum lift could be increased by 50% simply by quickly pitching up. If the stall AoA is approached rapidly, the boundary layer over most of the wing has still the characteristics which go with the low AoA that prevailed when that parcel of air flowed around the wing's nose. Once that boundary layer has been washed away, the airplane is deeply in stall territory and needs to pitch down a lot to recover. Pitch fast enough, and normally benign aircraft can show dangerous stall characteristics. This is fun to try, but make sure you have enough altitude below you to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now for the influence of Mach number. Again, &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;this post&lt;/a&gt; has more details (scroll down to the lower five paragraphs). Once part of the flow over the wing becomes supersonic, maximum lift suffers and the stall angle of attack is lowered dramatically. This is a high-speed stall, and it can become hard to recover. Stalling means a loss of lift, so the aircraft will pitch down, picking up more speed. This will drive it deeper into the high Mach region with severe shocks on the wing, so by accelerating it will make the stalling condition worse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially high altitude aircraft can get into a condition where they fly right between the low-speed and the high-speed stall. Decelerating means increasing the angle of attack above it's maximum, and accelerating means the shocks on the wings get worse, reducing lift and forcing the aircraft into a prolonged shallow dive, until air density is sufficient for recovery. U-2 pilots called this the coffin corner of the flight envelope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing sweep increases the maximum angle of attack, and with leading edge sweep angles of 60° and more, flow separation at the leading edge creates a vortex which increases lift with higher angles of attack, so that a normal stall does not occur. Of course, pitch high enough and the vortex will become unstable, but increased drag, separated flow around the vertical tail and vortices on the forward fuselage will limit how high you can pitch. The F-4 Phantom II has a maximum angle of attack at just 23°, where the wings will happily produce a positive lift gradient with angle of attack. But the vertical tail rapidly becomes ineffective beyond those 23°, and the aircraft will violently yaw out of control if that angle is exceeded (nose slice). Effectively, aircraft like the F-4 never stall, they just go out of control if you pitch up too much.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-06-18T21:07:02.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6376" PostTypeId="1" AcceptedAnswerId="6377" CreationDate="2014-06-18T23:33:49.550" Score="10" ViewCount="1695" Body="&lt;p&gt;In the discussion of &lt;a href=&quot;https://aviation.stackexchange.com/questions/6361/why-doesnt-the-a380-use-its-outboard-thrust-reversers&quot; title=&quot;Why doesn&amp;#39;t the A380 use its outboard thrust reversers?&quot;&gt;Why doesn't the A380 use its outboard thrust reversers&lt;/a&gt;, one of the reasons given was that engines 1 and 4 would be at great risk of ingesting debris. It was pointed out that the 747 uses reversers on all 4 engines, and it's just as big (overhanging edge of runway). So I asked in a comment:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If there is fear that the outboard engines would ingest crap (FOD)&#xA;because they overhang the edge of the runway, why wouldn't that also&#xA;apply to takeoff, when the outboard engines are presumably at high&#xA;thrust? &lt;em&gt;Additional: I realize that the jet blast is straight back, but suction on the front of the engine is pretty strong, too (enough to inhale a baggage cart).&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does an engine at reverse thrust kick air (and debris) far enough&#xA;&lt;em&gt;forward&lt;/em&gt; that there is a real risk of ingestion and FOD?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Could that be negated by designing the reverse thrusters to go&#xA;mostly sideways?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I was asked to repost as a separate question, so here it is...&lt;/p&gt;&#xA;" OwnerUserId="1078" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-07-04T09:58:09.410" Title="Is there a real risk of ingesting FOD into jet engines when using thrust reversers?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;airbus-a380&gt;&lt;boeing-747&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6377" PostTypeId="2" ParentId="6376" CreationDate="2014-06-19T01:27:23.793" Score="8" Body="&lt;p&gt;For the numbered items:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) and (2) At takeoff there is (typically, but there are birds) nothing solid that's airborne in front of the airplane, whereas thrust reversers can put small but solid airborne material in front of the engines, especially if they're still being used with high power as the airplane slows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) If you're saying that the air is only directed sideways rather that forward, that would cancel the forward thrust from that air, but it wouldn't get you much braking action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some other points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The higher the airplane's speed, the more braking action you get from the reversers, so if you're going to use them, get into them as soon as possible.&lt;/li&gt;&#xA;&lt;li&gt;If it's late night or early morning, and the airport has a noise problem, consider going into reverse but leaving the engines at idle. You'll still get significant braking proportional to the airplane's speed.&lt;/li&gt;&#xA;&lt;li&gt;If you've got a long runway, consider using just idle or less than high-power reverse. In other words, use what you need/want, but no more.&lt;/li&gt;&#xA;&lt;li&gt;Make sure you start out of a high power reverse well before slowing to taxi speed. There are speed guidelines for this, but I forget what they are. Actually, it's best in my opinion to avoid high-power reverse unless you really need it.&lt;/li&gt;&#xA;&lt;li&gt;Make sure you're completely out of reverse by the time you reach taxi speed. Again, I've forgotten the guideline.&lt;/li&gt;&#xA;&lt;li&gt;Consider where you are. If you're in, say, Germany, you can expect the runways to be clean, in Spain maybe not as clean, in Zimbabwe definitely not as clean. You get the idea.&lt;/li&gt;&#xA;&lt;li&gt;Be really careful about using reverse on an icy runway. If your nose is not pointed straight down the runway, the reverse thrust will be working to put you off the side of the runway. An acquaintance of mine put a 747 off the runway at KJFK that way (totaled the airplane, a few people hurt, no fatalities).&lt;/li&gt;&#xA;&lt;li&gt;Consider the characters of the engines on the airplane. Perhaps this is no longer a consideration, but back in the 1990s, P&amp;amp;W engines on the 747 were relatively tolerant of compressor stalls brought on by using too much reverse power at too slow a speed. GE engines, however, were not so tolerant.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The second 747 carrier I worked for used to have maintenance done at Santa Barbara, CA. When we would pick up the airplane, they would close the relatively narrow runway after our takeoff and sweep it. Not a reverse thrust situation, but it does illustrate the FOD problem.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-06-19T01:27:23.793" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6378" PostTypeId="1" AcceptedAnswerId="6380" CreationDate="2014-06-19T01:34:29.263" Score="10" ViewCount="6483" Body="&lt;p&gt;Let's suppose a CFI can no longer qualify for a 1st or 2nd class physical, or maybe her/his 2nd class physical was 18 months ago. Can she/he still give required instruction and endorsements as long as they don't charge for their time and are not paid for it in any other way?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="258" LastEditDate="2014-08-29T15:51:49.077" LastActivityDate="2014-08-29T15:52:05.043" Title="Can a CFI give required instruction and endorsements on a 3rd class medical?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6379" PostTypeId="2" ParentId="6378" CreationDate="2014-06-19T02:14:49.350" Score="5" Body="&lt;p&gt;A CFI can give, and charge for instruction with a 3rd class medical.  If the training does not require the CFI to be PIC, then the instruction can be given (and charged for) with no medical at all.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-08-29T15:52:05.043" LastActivityDate="2014-08-29T15:52:05.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6380" PostTypeId="2" ParentId="6378" CreationDate="2014-06-19T02:14:56.300" Score="12" Body="&lt;p&gt;A CFI with a third class medical can provide any kind of instruction that they are qualified for (and be compensated for it), per &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.23&quot;&gt;14 CFR 61.23(a)(3)(iv) and (v)&lt;/a&gt;. The FAA's position in these scenarios is that you're being compensated for the transference of knowledge, not the operation of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For completeness, A CFI can provide instruction WITHOUT a medical if they are not flying PIC or acting as a required crew member. In this scenario training can be provided for certain additional ratings (e.g. commercial) or flight reviews AS LONG AS the student can PIC during that flight AND the CFI is NOT a required crew member (i.e. safety pilot for insturment training).  Additionally, the FAA has made a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/Interpretations/data/interps/2014/Schaffner%20-%20%282014%29%20Legal%20Interpretation.pdf&quot;&gt;legal interpretation&lt;/a&gt; that a CFI can provide instruction to a pilot that is not current to carry passengers, as long as all other requirements for the student to be PIC can be met.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific regulations that allows this are &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.3&quot;&gt;14 CFR 61.3(c)(2)(viii)&lt;/a&gt; and &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.23&quot;&gt;14 CFR 61.23(b)(5)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-06-19T02:32:17.373" LastActivityDate="2014-06-19T02:32:17.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6381" PostTypeId="1" AcceptedAnswerId="6382" CreationDate="2014-06-19T03:24:38.173" Score="9" ViewCount="1162" Body="&lt;p&gt;Where I fly, it is customary for a pilot maintaining instrument currency to pay all the costs associated with the training flight while a safety pilot volunteers their time in exchange for the opportunity to log PIC. I personally don't disagree with this arrangement, since it encourages pilots to help each other out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has repeatedly taken the position that building up flight time is considered compensatory in nature when the pilot does not pay the costs to operate the aircraft (see &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/1997/harrington%20-%20%281997%29%20legal%20interpretation.pdf&quot;&gt;Harrington 1997&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/1990/lincoln%20-%20%281990%29%20legal%20interpretation.pdf&quot;&gt;Lincoln 1990&lt;/a&gt;, and &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2013/Howell-PatriotsJetTeam%20-%20%282013%29%20Legal%20Interpretation.pdf&quot;&gt;Howell 2013&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in this case, is the safety pilot being &quot;compensated&quot; by logging PIC? I vaguely remember seeing something saying that the FAA did NOT consider this compensation, but I can't remember where I saw that...&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2018-07-13T00:57:52.957" Title="Is a safety pilot required to share costs?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6382" PostTypeId="2" ParentId="6381" CreationDate="2014-06-19T04:25:44.433" Score="10" Body="&lt;p&gt;This &lt;em&gt;actually came up &lt;a href=&quot;http://chat.stackexchange.com/transcript/12036/2014/6/13&quot;&gt;in chat&lt;/a&gt; recently&lt;/em&gt; -- the answer (if only the two pilots are on board) is a qualified &quot;No&quot;, not because the time isn't &quot;compensation&quot; but because the safety pilot is a &lt;em&gt;required crewmember&lt;/em&gt; for simulated instrument flight.&lt;br&gt;&#xA;Since both pilots are required crewmembers the safety pilot is not acting as a PIC of a flight carrying &lt;em&gt;passengers&lt;/em&gt; &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2012/trussell%20-%20(2012)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;as long as they are only acting as the Legal PIC while the other pilot is under the hood&lt;/a&gt;.&lt;br&gt;&#xA;(Note however that while neither pilot is in simulated instrument conditions the safety pilot is &lt;em&gt;not&lt;/em&gt; required crew, and therefore &lt;em&gt;someone&lt;/em&gt; is PIC of a flight carrying at least one passenger - so log your time carefully and try to wrap your head around a &quot;pro rata share&quot; of that mess.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is further addressed (more directly) in &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2012/roberts,%20andrew%20-%20(2012)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the interpretation issued to Roberts, July 11, 2012&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that if we're talking about a flight with more than the two pilots on board (carrying someone who is &lt;strong&gt;&lt;em&gt;NOT&lt;/em&gt;&lt;/strong&gt; a required crewmember, like a friend in the back seat) then the whole thing goes out the window: No matter who is acting as the Legal PIC for the flight they're &quot;PIC of a flight carrying passengers&quot;, and you're back to &lt;a href=&quot;https://aviation.stackexchange.com/questions/6300/where-is-the-term-pro-rata-defined-as-it-is-used-in-61-113c&quot;&gt;pro rata share&lt;/a&gt; territory.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="8114" LastEditDate="2018-07-13T00:57:52.957" LastActivityDate="2018-07-13T00:57:52.957" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="6383" PostTypeId="1" AcceptedAnswerId="6386" CreationDate="2014-06-19T06:19:09.860" Score="-1" ViewCount="2976" Body="&lt;p&gt;Malaysia originally claimed they saw MH370 on military radar climb to 45,000ft (in excess of its service ceiling) then drop 40,000ft (12,000m/6.47nm) within 60 seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prior to May 2014 Malaysia claimed MH370 was seen on radar flying IGARI-VAMPI-GIVAL-IGREX, but when asked to produce radar tracking data for this could not do so.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Preliminary Accident Report published 1st May 2014, the report stated unequivocally that it was not seen on LUMPUR civil SSR radar after 1:21am until next seen in the Straits of Malacca on military radar. Malaysia could not or would not publish radar imagery for the mystery aircraft sighted in the Straights of Malacca, however on 21 March they displayed this image at the Lido Hotel in Beijing which they claimed showed MH370 in the Straits of Malacca:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/epg1m.jpg&quot; alt=&quot;Lido Hotel imagery&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By default therefore this image has become the de facto radar image for MH370's flight which incidentally does not show MH370 flying IGARI-VAMPI-GIVAL-IGREX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is part of that image with time stamps made clearer by focus sharpening tools:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3NK2W.jpg&quot; alt=&quot;Time stamps&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the time stamp imagery it is now possible to calibrate that flight more precisely by measuring the time elapsed over known geographical points and then creating a calibration scale beside the track. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That calibration suggests that this aircraft flew over a small island, Pelau Perak at precisely 2:03am on a track leading back to the southwest tip of Palau Penang. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/b5OAp.jpg&quot; alt=&quot;Pelau Perak&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The preliminary accident report also notes MH370 was reported by Ho Chi Minh being lost over waypoint BITOD at a time which is inferred as 1:24am MYT. The Preliminary Accident Report issued by the Malaysian Government states unequivocally that it was lost from radar at BITOD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jJgEZ.png&quot; alt=&quot;Malaysian Government statement regards BITOD&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;This poses a serious problem since it appears to only allow MH370 39 minutes to return to Pelau Perak at the maximum speeds for low altitude flight.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This flight over a track distance of 338nm requires an average TAS airspeed of 520kt. Something which requires the aircraft to fly at altitudes where it would logically have to have been seen by several radar stations. Radar at Aceh and at Singapore must have seen MH370 flying west flying at 38,000ft yet they did not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If MH370 flew west at these altitudes it should have been seen by at least half a dozen radar stations. Malaysia however claimed that it flew back at 5,000ft like a fighter plane to evade radar and flew low over Kota Bharu. How could it do all this if it had to maintain a speed only achievable at 38,000ft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rsU08.jpg&quot; alt=&quot;Airspeed chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air temperature at Kota Bharu was 22 deg C and there was a light nor-easterly breeze of between 5-10 knots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;VMO for a B777 with this surface temperature is 350 knots TAS at 5,000ft. At this altitude logically it could not have flown west within 39 minutes. Even if one is generous and allows that it turned back at IGARI affording another three minutes it still does not seem credible since the track would still require 54 minutes of flying.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KOiZw.jpg&quot; alt=&quot;Time constraints&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/w20Vj.jpg&quot; alt=&quot;12,000ft flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is how did this aircraft fly back west so fast without being seen? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did it fly low, or did it fly high?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain of JAL750 reported he spoke with the co-pilot of MH370 by VHF just after 1:30am. He said all appeared normal when he spoke to MH370. JAL750 at that time was flying NE from Ho Chi Minh at 32,000ft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;JAL750 was at least 398nm away from IGARI. Had MH370 dropped to 5000ft and flown west it would have been out of VHF range to speak with JAL750. This image has a circle for the estimated radar horizon between JAL750 and another aircraft at 5,000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z5Rkf.jpg&quot; alt=&quot;JAL750 VHF range&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would appreciate if I someone could give a cohesive explanation for apparent inconsistencies in the official account?  &lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="2357" LastEditDate="2014-06-20T11:27:05.393" LastActivityDate="2014-06-20T11:27:05.393" Title="How could MH370 fly west to Straits of Malacca within time frame without being seen on Radar?" Tags="&lt;air-traffic-control&gt;&lt;aircraft-performance&gt;&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ClosedDate="2014-06-19T18:54:13.973" ContentLicense="CC BY-SA 3.0" />
  <row Id="6385" PostTypeId="1" AcceptedAnswerId="6388" CreationDate="2014-06-19T08:10:46.673" Score="26" ViewCount="6218" Body="&lt;p&gt;On commercial airliners, the FCOM (Flight Crew Operating Manual) sometimes gives instructions to the pilots to land sooner than planned, following various in-flight failures or emergencies. For instance, for serious emergencies (e.g. in-flight fire), the pilots would be instructed to &lt;code&gt;LAND ASAP&lt;/code&gt; (as soon as possible), as there is a real danger to the aircraft and its occupants if they stay in the air any longer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For less severe situations, the pilots would be instructed to &lt;code&gt;LAND ANSA&lt;/code&gt; (at nearest suitable airport), which gives them more leeway in deciding where to land.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: other than the fact that &lt;code&gt;LAND ASAP&lt;/code&gt; is obviously more urgent than &lt;code&gt;LAND ANSA&lt;/code&gt;, could anyone go into more details as to how a pilot would interpret these instructions, and how they differ? (for instance, does &lt;code&gt;LAND ASAP&lt;/code&gt; mean &quot;land on the nearest reasonably smooth surface&quot;, or is it less extreme than that? Are there guidelines on approximately how long you should keep flying after receiving a &lt;code&gt;LAND ANSA&lt;/code&gt; instruction?)&lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="572" LastEditDate="2015-02-19T09:14:37.937" LastActivityDate="2020-02-11T17:40:52.233" Title="What is the difference between being instructed to land &quot;as soon as possible&quot; or &quot;at nearest suitable airport&quot;?" Tags="&lt;emergency&gt;&lt;commercial-aviation&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6386" PostTypeId="2" ParentId="6383" CreationDate="2014-06-19T10:34:02.607" Score="5" Body="&lt;p&gt;The essence of your question seems to be&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Did Malaysian officials claim MH370 flew from BITOD to Palau Perak in 39 minutes?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently I don't see enough primary evidence to support that claim.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Use of waypoint names by officials&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is clear (to me at least) that when officials talk to the press, they use waypoint names rather than baffling the journalists by reading out lengthy sets of latitudes and longitudes. Waypoint names are less likely to be confused or mistranscribed than lengthy sets of digits. It is also likely that as the information passes from technical staff examining logs up to officials, that indigestible coordinates are simplified to waypoint names to help those officials quickly grasp the essentials. I believe it is a mistake to infer any specific accuracy such as *within 1 nm of the named waypoint&quot;, It is probably best to interpret any mention of a waypoint as meaning the aircraft was closer to this waypoint than to any other major waypoint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an official reports that MH370 flew on a route between IGARI and VAMPI, I believe it is a mistake to infer that they mean the aircraft flew from a position precisely at IGARI along a &quot;straight line&quot; to a position precisely over VAMPI. I would infer no more than the aircraft spent some time in a large area bounded on the east by IGARI and bounded on the west by VAMPI and that it was headed in a direction that took it more towards VAMPI than IGARI. It might have flown roughly SW or roughly W or any direction in between.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The evidence that MH370 was in the region of BITOD is in &lt;a href=&quot;http://www.straitstimes.com/sites/straitstimes.com/files/20140501/MH370%20-%20Actions%20taken%20between%200138%20and%200614_0.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5D27Y.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, I would interpret that generously. It doesn't mean that MH370 was within some immeasurably tiny distance from BITOD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is of course also the possibility that the &quot;radar blip&quot; was a flock of birds.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Times&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I note that there is no mention in the document above of HCM's record of the time the &quot;radar blip&quot; was somewhere closer to BITOD than to IGARI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say &lt;em&gt;&quot;at a time which is inferred as 1:24am MYT.&quot;&lt;/em&gt; but you don't say who made that inference and you don't provide any references to official information. The question would, in my view, be a lot better if it gave references (links) to official Malaysian documents for each claim made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the question doesn't show that the Malaysian government stated that they believe MH370 was at BITOD at 1:24am MYT, it isn't possible to identify any inconsistency.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Palau Perak&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On the very heavily annotated images you show, it looks like the label &quot;Palau Perak&quot; was added by some anonymous person and was not present on the original slide shown at the press conference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To draw firm conclusions, I believe, you really need to make use of more direct and clear information.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At the moment, I don't think there's sufficient primary evidence to identify any incontrovertible inconsistency. I look forward to seeing some better references edited into the question.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-06-19T10:34:02.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6388" PostTypeId="2" ParentId="6385" CreationDate="2014-06-19T15:07:56.097" Score="20" Body="&lt;p&gt;I would interpret them as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ASAP means the plane is going to kill you. Soon. So land before that happens. Short runways, military airports, abandoned airfields, a decent highway, dry lakes (e.g. Edwards AFB), calm bodies of water (e.g. the Hudson River) are all possibilities. Do not concern yourself with operational issues like taking off again, and bureaucratic formalities like immigration will be summarily ignored. Obviously if you are near the Hudson you would try very, very hard to reach JFK, Teterboro or Newark, but sometimes that doesn't work out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ANSA means try for a real airport considering immediate operational and bureaucratic requirements, but not beyond immediate. this could include turning around and landing at Goose Bay. Basically I'm going to punch &quot;Nearest&quot; on the Nav panel and make an educated choice. Most Nav sets will only show open airfields that can accommodate your aircraft. For example, Gimli would not have appeared for &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;Air Canada flight 143&lt;/a&gt;, assuming they had a suitable unit back then and the power hadn't gone out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The terms are deliberately unclear to give the pilot some flexibility - you can't predict and write a procedure for everything.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-06-21T01:00:03.637" LastActivityDate="2014-06-21T01:00:03.637" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6389" PostTypeId="1" AcceptedAnswerId="6390" CreationDate="2014-06-19T15:56:52.753" Score="38" ViewCount="36072" Body="&lt;p&gt;Shortly before take-off, and again before landing, the cockpit (no way to tell whether it was the Captain or First Officer) came on over the speakers, stating:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flight Attendant's, prepare for take-off/landing and cross-check&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is a cross-check?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2019-08-15T13:28:12.200" Title="What is a &quot;cross check&quot;?" Tags="&lt;crew&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6390" PostTypeId="2" ParentId="6389" CreationDate="2014-06-19T15:59:50.470" Score="32" Body="&lt;p&gt;&lt;a href=&quot;http://www.askthepilot.com/how-to-speak-airline/&quot;&gt;This website&lt;/a&gt; has the definition:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Crosscheck is a generic term used by pilots and flight attendants&#xA;  meaning that one person has verified the task of another. In the&#xA;  cabin, flight attendants crosscheck one another’s stations to make&#xA;  sure the doors are armed or disarmed as necessary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-06-19T15:59:50.470" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="6391" PostTypeId="1" AcceptedAnswerId="6392" CreationDate="2014-06-19T17:20:21.120" Score="18" ViewCount="49035" Body="&lt;p&gt;Some airplanes have a button for the &quot;yaw damper.&quot;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the yaw damper?&lt;/li&gt;&#xA;&lt;li&gt;When is it used?&lt;/li&gt;&#xA;&lt;li&gt;Is it ever required for certification or operation?&lt;/li&gt;&#xA;&lt;li&gt;How does it work?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2017-01-31T19:23:29.180" LastActivityDate="2020-05-22T00:48:17.790" Title="What is the &quot;yaw damper&quot;?" Tags="&lt;flight-controls&gt;&lt;yaw-damper&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6392" PostTypeId="2" ParentId="6391" CreationDate="2014-06-19T18:13:13.220" Score="16" Body="&lt;p&gt;The &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Yaw_damper&quot;&gt;yaw damper&lt;/a&gt;&lt;/strong&gt; is, in simplest terms, an &quot;autopilot&quot; for yaw. When engaged, it operates the rudder (or whatever yaw control method is available in exotic aircraft, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#Flight_controls&quot;&gt;B-2 flying wing&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its primary goal is to counteract the typical &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot;&gt;Dutch roll&lt;/a&gt; aerodynamic mode of many aircraft. It also helps keep turns &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_flight&quot;&gt;coordinated&lt;/a&gt; by automatically providing the necessary rudder inputs to avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Sideslip_angle&quot;&gt;slipping/skidding&lt;/a&gt; in a  turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In normal aircraft the yaw damper &lt;a href=&quot;http://en.wikipedia.org/wiki/Autopilot#Stability_augmentation_systems&quot;&gt;is part of the automatic flight control system (AFCS)&lt;/a&gt; or &quot;autopilot.&quot; It can usually be engaged on its own without the rest of the autopilot. On the other hand, most autopilots require the yaw damper to be engaged when the rest of the autopilot is engaged (you can have yaw damper without autopilot, but not autopilot without yaw damper).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For large / transport aircraft, the yaw damper is usually engaged throughout the entire flight profile except for takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/part-25/subpart-B&quot;&gt;It is required equipment&lt;/a&gt; (link is to FAA certification regs but similar regs apply elsewhere) in many (most?) transport aircraft, which tend to suffer Dutch roll instability, but flights can sometimes still be made if the yaw damper is inoperable per the &lt;a href=&quot;http://en.wikipedia.org/wiki/Master_minimum_equipment_list&quot;&gt;minimum equipment list (MEL)&lt;/a&gt;, with restrictions. This depends on the exact aircraft type and any extra operator policies (company rules). Note that usually an inoperable yaw damper also precludes the use of the rest of the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern digital yaw dampers are part of an integrated digital autopilot system. They use accelerometers and rate sensors to determine the aircraft's motion. It then runs the numbers through special algorithms to determine what rudder inputs need to be made in order to damp any Dutch roll and to coordinate a turn. It then provides those rudder commands to a servo or hydraulic system which operates the rudder.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-06-19T18:45:30.273" LastActivityDate="2014-06-19T18:45:30.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6393" PostTypeId="2" ParentId="6391" CreationDate="2014-06-19T18:24:27.803" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the yaw damper?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The yaw damper is a Stability Augmentation System&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/94hst.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;from &lt;a href=&quot;http://books.google.de/books?id=T0Ux6av4btIC&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Control and Simulation&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does it work?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is an automated system that uses the &lt;em&gt;yaw rate&lt;/em&gt; of the aircraft (the aircraft thus need to be equipped with a sensor able to measure it) to command the rudder (the aircraft thus need to be equipped with an actuator capable of deflecting the rudder without pilot intervention) in such a way that the yaw oscillations will be damped faster than naturally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircrafts are naturally stable around the yaw axis (called &quot;Weathercock stability&quot;), but such natural stability (mostly due to the vertical part of the tail) might not be very damped, meaning that if uncontrolled, oscillations around the yaw axis would continue for a long time before dying off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The yaw damper aims to reduce the duration of these oscillations.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When is it used?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whenever there is the need of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually it should not create problems to the pilot or the safety of the aircraft, but there might be situations in which you might want to disable it, such as when you have to quickly perform a de-crab: a traditional (yaw-rate based) yaw damper would slow down the maneuver.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it ever required for certification?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;N̶o̶t̶ ̶t̶o̶ ̶m̶y̶ ̶k̶n̶o̶w̶l̶e̶d̶g̶e̶.̶&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to dvnrrs for pointing out that yaw dampers are required for certification of transport aicraft whose flight-test-demonstrated Dutch roll instability exceed certain limits. The relevant requirements are in &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/25.181&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §25.181.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it ever required for operation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As dvnrrs mentions in his &lt;a href=&quot;https://aviation.stackexchange.com/a/6392/1467&quot;&gt;answer&lt;/a&gt;, higher level autopilots are usually not engaged if the SASs are deactivated.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-06-20T07:00:32.197" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="6394" PostTypeId="2" ParentId="2907" CreationDate="2014-06-19T20:11:30.853" Score="0" Body="&lt;p&gt;If pilots are alive and conscious they will generally be sufficiently aware by other clues. Given that ADS-C which MH370 was using is contracted to ATS without a transponder the feedback from ATS would cease. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are only so many alarms you can bombard a pilot with before it becomes a counter-productive distraction in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is just a presumption that MH370's transponder was turned off since the Flight Aware website notes that MH370's transponder did briefly send signals again about three hours after take-off at 03:48-03:51 MYT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because these transponder returns were prompted by MH370 flying through civil radar coverage and being painted by civilian PSR radar then it may be that it flew through a gap in radar coverage and MH370's transponder was not switched off at all. &lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="2357" LastEditDate="2014-06-19T20:47:28.813" LastActivityDate="2014-06-19T20:47:28.813" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6395" PostTypeId="2" ParentId="6276" CreationDate="2014-06-19T20:54:56.377" Score="1" Body="&lt;p&gt;You are more likely to kill yourself in a stall/spin trying to turn back than you are from a forced landing straight ahead. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the altitude required to make a successful 180 turn is quite considerable the chances are if you are high enough you will be too far from the runway to make it back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember seeing an article in plane and pilot magazine back in 1974 dealing with that topic and I seem to recall anything below 780ft AGL was a no-go &lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="64" LastEditDate="2014-06-19T22:23:44.340" LastActivityDate="2014-06-19T22:23:44.340" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6396" PostTypeId="2" ParentId="1251" CreationDate="2014-06-19T21:06:02.947" Score="-4" Body="&lt;p&gt;VMO and VMC are both important&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;VMO&lt;/strong&gt; = Maximum Operating Speed, a structurally safe maximum speed which varies with altitude. For example with an emergency descent in a B777 the VMO is 310kt IAS, but in level flight it is 330 KIAS. As you climb the air thins so the true airspeed increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;VMC&lt;/strong&gt; = Minimum Controllable Speed with one engine inoperative, gear retracted with CG at most rearward limit, bad engine at idle but not feathered (if propellor)&lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-06-19T21:06:02.947" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6397" PostTypeId="2" ParentId="2561" CreationDate="2014-06-19T21:10:03.233" Score="0" Body="&lt;p&gt;Generally I would ease power back at circuit altitude, trim and then if a climb was required, then I would climb at cruise revs.  &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-06-19T21:10:03.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6398" PostTypeId="1" CreationDate="2014-06-19T21:35:38.677" Score="6" ViewCount="2016" Body="&lt;p&gt;What I am looking for here is a sort of a list gathering the manoeuvres and/or load cases imposed by regulation that lead to the sizing of a part of an aircraft. For instance, vertical gust load is often the load case that has to be used to size the structural parameters of the horizontal tail (bending moment). What are the other load cases and manoeuvres that usually size the subparts of a commercial aircraft ?&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="19" LastEditDate="2016-06-22T07:55:18.417" LastActivityDate="2016-06-22T07:55:18.417" Title="What regulatory load cases drive the structural design of aircraft?" Tags="&lt;aircraft-design&gt;&lt;maneuver&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6399" PostTypeId="1" AcceptedAnswerId="6400" CreationDate="2014-06-19T23:08:26.850" Score="47" ViewCount="28538" Body="&lt;p&gt;Flying home from the Denver ComiCon, on a 737, I saw an angled flange on the engine. Could you describe its purpose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GdMb0.jpg&quot; alt=&quot;Flange1&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/EYwvA.jpg&quot; alt=&quot;Flange2&quot;&gt;&#xA;&lt;sup&gt;Photos by &lt;a href=&quot;https://aviation.stackexchange.com/users/2171/cgcampbell&quot;&gt;CGCampbell&lt;/a&gt; licensed &lt;a href=&quot;https://creativecommons.org/publicdomain/zero/1.0/&quot; rel=&quot;noreferrer&quot;&gt;CC0&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="3386" LastEditorDisplayName="user12485" LastEditDate="2019-12-06T08:23:12.537" LastActivityDate="2020-01-16T08:32:58.557" Title="What is this flange on the engine?" Tags="&lt;jet-engine&gt;&lt;boeing-737&gt;&lt;feature-identification&gt;&lt;nacelle&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="6400" PostTypeId="2" ParentId="6399" CreationDate="2014-06-19T23:25:31.767" Score="53" Body="&lt;p&gt;This is called a &quot;strake&quot; or &quot;&lt;a href=&quot;https://www.google.com/patents/US6964397&quot; rel=&quot;noreferrer&quot;&gt;chine&lt;/a&gt;&quot; (Aerodynamic fan cowl strake/chine, Nacelle strake/chine).&lt;br&gt;&#xA;They allow the aircraft to generate more lift at lower speeds, which entails such positive consequences as lower stall speeds, lower landing speeds, lower take-off speeds and shorter runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strakes should be used if the nacelles are mounted closely under the wing of the aircraft, see also &lt;a href=&quot;https://aviation.stackexchange.com/questions/5160/why-dont-all-aircraft-use-need-nacelle-chines&quot;&gt;Why don't all aircraft use/need nacelle chines?&lt;/a&gt;. Nacelles are usually mounted like that in order to&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;maximize the distance between the lower nacelle side and the runway, so that the engine/fan cowl/nacelle doesn't hit the ground during violent landings when the wings bend down, and in order to&lt;/li&gt;&#xA;&lt;li&gt;minimize the risk for runway debris being sucked into the engine.&lt;/li&gt;&#xA;&lt;li&gt;Source: &lt;a href=&quot;http://dx.doi.org/10.1007/978-3-642-34539-5&quot; rel=&quot;noreferrer&quot;&gt;Flugzeugtriebwerke, Bräunling Willy J.G., VDI-Buch, Springer Vieweg, 2015&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.google.com/patents/US20100176249&quot; rel=&quot;noreferrer&quot;&gt;US Patent 20100176249: Engine Nacelle Of An Aircraft Comprising A Vortex Generator Arrangement&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With an optimal arrangement and at high angles of attack, such vortex generators, which are known as nacelle &lt;em&gt;strakes&lt;/em&gt; or &lt;em&gt;chines&lt;/em&gt;, generate a powerful vortex that flows over the wing, where on a slat in front of said wing it delays airflow separation until the aircraft flies at greater angles of attack.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ewu6J.png&quot; alt=&quot;Patent sketch of the vortex generator with the generated vortices&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea dates back to 1971 (&lt;a href=&quot;https://www.google.com/patents/US3744745&quot; rel=&quot;noreferrer&quot;&gt;US Patent 3744745: Liftvanes&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;in operational conditions wherein high angles of attack are encountered, such as in landing or takeoff, the vanes oppose the strong upwash around the nacelle, reducing the flow separation on its upper areas, and providing a strong downwash marked by marginal trailing vortices&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jtdDh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/6.1985-4067&quot; rel=&quot;noreferrer&quot;&gt;R.S. Shevell. Aerodynamic Bugs: Can CFD spray them away? 1985&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DC-10 wind tunnel tests showed a significant loss in maximum lift&#xA;  coefficient in the flap deflected configurations, with landing slat&#xA;  extension, compared to predictions. This resulted in a stall speed&#xA;  increase of about 5 knots in the approach configuration. The initial&#xA;  wing stall occured behind the nacelles and forward of the inboard&#xA;  ailerons. The problem was traced by flow visualization techniques to the&#xA;  effects of the nacelle wake at high angles of attack and the absence of&#xA;  the slat in the vicinity of the nacelle pylons. The solution was&#xA;  developed in the NASA Ames Research Center 12 ft. pressurized tunnel and&#xA;  turned out to be a pair of strakes mounted forward on each side of the&#xA;  nacelles in planes about 45 degrees above the horizontal. The final&#xA;  strake shape was optimized in flight tests. The strakes are simply&#xA;  large vortex generators. The vortices mix the nacelle boundary layer air&#xA;  with the free stream and reduce the momentum loss in the wake. The&#xA;  vortices then pass just over the upper surface of the wing, continuing&#xA;  this mixing process. The counterrotating vortices also create a downwash&#xA;  over the wing region unprotected by the slat, further reducing the&#xA;  premature stall. The effect of the strakes is to reduce the required&#xA;  takeoff and landing field lengths by about 6%, a very large effect.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-12-06T15:08:00.840" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6401" PostTypeId="1" AcceptedAnswerId="6402" CreationDate="2014-06-20T00:04:34.903" Score="8" ViewCount="1150" Body="&lt;p&gt;I've recently starting riding a push bike to work and got myself a CO2 pump and some cartridges (like &lt;a href=&quot;http://www.cyclingdeal.com.au/buy/8x-cycling-bike-air-pump-inflator-co2-cartridges/8CO2C?gclid=CjkKEQjwlIqdBRDy6JSK4Lmn1akBEiQAVa9dPVhPUGKSPLsCFiJxwMRKGyyev7VG-EGt3g0CuF5eCSzw_wcB&quot;&gt;this&lt;/a&gt;), which I promptly forgot about. As a result, when going on work trips and holidays, I had a cartridge in my bag when going through airline security.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I estimate roughly 15 airports (some duplicates) either didn't detect the cartridge or just ignored it. Perth International is my main airport, but I also visited Singapore 3 times (so bare minimum of 6 security checks there. Is this normal behavior/protocol? I would have thought that while CO2 cartridges are single use, they probably present more danger than other prohibited items, such as nail clippers. &lt;/p&gt;&#xA;" OwnerUserId="2652" LastEditorUserId="19" LastEditDate="2016-12-05T11:30:11.370" LastActivityDate="2016-12-05T11:30:11.370" Title="Are CO2 cartridges not considered explosive?" Tags="&lt;security&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6402" PostTypeId="2" ParentId="6401" CreationDate="2014-06-20T00:23:14.487" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I had a cartridge in my bag when going through airline security.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These are not uncommon. They are also used in for instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Life Vests&lt;/li&gt;&#xA;&lt;li&gt;Ski Airbags&lt;/li&gt;&#xA;&lt;li&gt;Soft air guns&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In other words, it's not an unusual object, especially for holidays which I guess both your two mentioned destinations might be for many travellers. I've checked in my bag with an automatic self-inflating life vests a few times and while it went in the  hold never had any problems or found it removed. I believe there may be some limitations though on the number you can pass through, and they might start asking questions if you have more than two.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I estimate roughly 15 airports (some duplicates) either didn't detect the cartridge or just ignored it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's not unjustified not checking them in. Onboard pressure changes, the cargo hold is cold and will shake during turbulence which just might trigger it to deploy if left screwed onto a life vest of similar.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;probably present more danger than other prohibited items, such as nail clippers&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can't see any real threat posed by these, except for the gun application, which of course requires a gun and not only a cartridge. Btw, TSA &lt;a href=&quot;http://blog.tsa.gov/2009/05/tsa-urban-legends-nail-clippers.html&quot; rel=&quot;nofollow&quot;&gt;allows nail clippers&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ryanair, the World’s favourite airline ;) &lt;a href=&quot;http://www.ryanair.com/en/questions/can-i-bring-a-self-inflating-lifejacket/&quot; rel=&quot;nofollow&quot;&gt;states&lt;/a&gt; the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Carriage of Self Inflating Lifejacket&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A self inflating lifejacket with 2 carbon dioxide cylinders (plus 2&#xA;  spares) can be included in either cabin or checked baggage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, they appear pretty liberal on the matter.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-06-20T20:47:24.163" LastActivityDate="2014-06-20T20:47:24.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6403" PostTypeId="1" AcceptedAnswerId="6404" CreationDate="2014-06-20T04:41:43.003" Score="4" ViewCount="549" Body="&lt;p&gt;My AME just called to let me know that my &lt;a href=&quot;https://aviation.stackexchange.com/questions/1747/faa-class-3-medical-re-examination&quot;&gt;FAA Class 3 medical certificate&lt;/a&gt; had been issued and was sent to me via airmail from United States to China. Since April 7th, 2014 when it was dispatched, it has been over 2 months now and I still don't receive the certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I called local postal office and was told I needed to find a 13-digits tracking number (e.g. AB123456789CD, 13 digits, with 2 alphabetic letters at the beginning and end of the string and 9 digits in between) of the mail so they could check for me. The problem is I don't have it and I have no idea where to find it on the &lt;a href=&quot;https://medxpress.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://medxpress.faa.gov&lt;/a&gt; website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone help me on how I can get this number? What are my options should I fail to get ahold of the certificate?&lt;/p&gt;&#xA;" OwnerUserId="869" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-06-20T05:13:23.347" Title="What if I fail to receive FAA Medical Certificate via mail?" Tags="&lt;faa&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6404" PostTypeId="2" ParentId="6403" CreationDate="2014-06-20T05:13:23.347" Score="4" Body="&lt;p&gt;You're really asking a postal service question (and from my experience with the postal service you're probably out of luck, even if you had the tracking number: Unfortunately when the USPS hands packages off to other nations' postal services that's often the last tracking update - either the item gets to its recipient or not, but it's gone into a black hole).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case the answer to the aviation/FAA half of the question (&quot;I haven't gotten my new medical certificate yet - what do I do now?&quot;) is much simpler, and involves more helpful people than international mail: &quot;Contact the Medical Certification branch&quot; (&lt;a href=&quot;http://www.faa.gov/licenses_certificates/medical_certification/request_copy/&quot; rel=&quot;nofollow&quot;&gt;see here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this particular case you want to actually call them on the phone and speak to a human being to determine (a) if they have a tracking number, and (b) how to proceed to ensure that you have a valid medical certificate in your possession.&lt;br&gt;&#xA;I know in cases like this the Medical Certification branch can also fax you a copy of the certificate (I believe these are valid for 60 days) while you try to get things straightened out and get the actual paper certificate in your hands.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-20T05:13:23.347" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="6405" PostTypeId="2" ParentId="2060" CreationDate="2014-06-20T07:40:30.340" Score="0" Body="&lt;p&gt;With EFIS glass cockpits data specific to an aircraft type from the Flight Computer are displayed on the screen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That screen and a standard layout however could be a common feature on several aircraft from the same manufacturer which as Jan Hudec points out lead to common type ratings allowing pilots to be cross rated on more than one aircraft. &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-06-20T07:40:30.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6406" PostTypeId="1" CreationDate="2014-06-20T11:42:09.537" Score="2" ViewCount="1399" Body="&lt;p&gt;I'm having a class about Database management system, and the professor gave us a project regarding Air traffic control system. The exact assignment is to &quot;Design and create a system which can manage informations of Air Traffic Control System, summarize entities and how system works&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not asking you to do this for me, what I would like to know is&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;what should i know about air traffic control systems?&lt;/li&gt;&#xA;&lt;li&gt;how does it work?&lt;/li&gt;&#xA;&lt;li&gt;what are the entities involved in it?&lt;/li&gt;&#xA;&lt;li&gt;what is an air traffic control system?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2654" LastEditorUserId="1467" LastEditDate="2014-06-20T12:01:19.730" LastActivityDate="2014-06-20T12:57:21.330" Title="Air Traffic Control System management" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ClosedDate="2014-06-27T12:01:51.780" ContentLicense="CC BY-SA 3.0" />
  <row Id="6407" PostTypeId="2" ParentId="6406" CreationDate="2014-06-20T12:57:21.330" Score="7" Body="&lt;p&gt;Air traffic control system is the computer system that air traffic controllers use to keep track of the aircraft they are controlling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system processes data from the primary and especially a secondary radar and displays them in suitable fashion for easy understanding by the controllers. The radar processing itself is not interesting for database class. But there is a bunch of information about each aircraft that needs to be remembered and associated with it's radar image:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The assigned transponder 4 octal digit code (usually called &quot;squawk&quot;). This is a code the secondary radar receives from the aircraft used to associate the data to the correct radar return.&lt;/li&gt;&#xA;&lt;li&gt;Identification, also used as callsign. It is registration number or flight number (sometimes internal company flight number that is different from what they show in time tables)&lt;/li&gt;&#xA;&lt;li&gt;Aircraft type&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft type is needed so the controller knows the performance of the aircraft, so it needs associated performance data like maximum speed, approach speed, maximum altitude etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Flight plan. This needs to contain:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Start and destination airports&lt;/li&gt;&#xA;&lt;li&gt;Preferred cruise altitude and speed&lt;/li&gt;&#xA;&lt;li&gt;List of waypoints&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You may consider current clearance limit (altitude and waypoint); I am not sure whether the current systems include it or not.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-06-20T12:57:21.330" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="6408" PostTypeId="2" ParentId="3826" CreationDate="2014-06-20T14:41:22.120" Score="11" Body="&lt;p&gt;As a balloon pilot: no we do not.  We do fly regularly in classes G, D, and E and will occasionally wander into class C; but it is very frowned upon...and you better have an aircraft radio or at least call the tower to let them know you are there.   Of course balloons always have right-of-way so if you see us get out of the way; we can't control where we're going. &lt;/p&gt;&#xA;" OwnerUserId="2656" LastActivityDate="2014-06-20T14:41:22.120" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="6410" PostTypeId="2" ParentId="121" CreationDate="2014-06-20T16:26:48.117" Score="2" Body="&lt;p&gt;Tethering for balloons is largely left up to the manufacturer.  Most have specific requirements / recommendations in the aircraft manual.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most pilots and manufacturers will recommend a 'three-point' tie-off system.  This system connects three ropes from the top of the balloon to the up-rights on the basket and then attaches a secondary rope to each of those which is tied to a car or truck.  This provides a stable tethering system that 'holds' the envelope in place is very robust.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Manufactures normally also allow three ropes to be connected to the uprights only but if it gets windy this can be very hard on the system. I looked around for the PDF version of my manual but am having a hard time finding it; its even got illustrations.&lt;/p&gt;&#xA;" OwnerUserId="2656" LastActivityDate="2014-06-20T16:26:48.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6411" PostTypeId="1" AcceptedAnswerId="6412" CreationDate="2014-06-20T16:42:54.953" Score="16" ViewCount="7839" Body="&lt;p&gt;Knowing that the &lt;strong&gt;Wright Flyer&lt;/strong&gt; was the first successful heavier-than-air powered aircraft, I'm fascinated by its operation requiring a &lt;em&gt;prone position&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Searching further, I was surprised to find out that the recent &lt;a href=&quot;http://www.electricmotorglider.com/Design%20Goals.html&quot; rel=&quot;noreferrer&quot;&gt;EMG-5&lt;/a&gt; motorglider also puts the pilot in a &quot;prone&quot; position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xd2wr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;My question:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Can someone expand on the alleged minimizing g-force effect of the prone pilot position. Why isn't it more common, especially in fighters?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="5517" LastEditDate="2015-02-23T20:03:42.033" LastActivityDate="2015-12-02T19:09:08.173" Title="Does a prone position for the pilot minimize g-force effects?" Tags="&lt;aircraft-design&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6412" PostTypeId="2" ParentId="6411" CreationDate="2014-06-20T16:53:10.507" Score="17" Body="&lt;p&gt;It is true that the body &lt;a href=&quot;http://en.wikipedia.org/wiki/Prone_position#Pilots_and_the_prone_position&quot;&gt;can withstand higher g-forces in the prone position&lt;/a&gt;. The reason is that in the prone position, g-forces don't pull blood down to the lower body and away from the brain, as happens in the seated position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept was explored for combat aircraft with the Italian &lt;a href=&quot;http://en.wikipedia.org/wiki/Savoia-Marchetti_SM.93&quot;&gt;Savoia-Marchetti SM.93&lt;/a&gt; and the British &lt;a href=&quot;http://en.wikipedia.org/wiki/Gloster_Meteor_F8_%22Prone_Pilot%22&quot;&gt;Gloster Meteor F8&lt;/a&gt;. These aircraft revealed some practical issues with the prone position:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is much less comfortable for the pilot than a seated position, especially during long flights.&lt;/li&gt;&#xA;&lt;li&gt;It is much more difficult to design an ejection/escape system. The Meteor F8 required the pilot to jettison the rudder pedals and crawl backwards to an escape hatch.&lt;/li&gt;&#xA;&lt;li&gt;It affords much less visibility to the pilot.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In light of these issues, it was found more practical to stick with seated pilots. In modern times, &lt;a href=&quot;http://en.wikipedia.org/wiki/G-suit&quot;&gt;g-suits&lt;/a&gt; and advanced training techniques like the &lt;a href=&quot;http://www.dragondoor.com/articles/power-breathing-the-jet-jock-style/&quot;&gt;&quot;hook&quot; maneuver&lt;/a&gt; have allowed fighter pilots to withstand higher g-forces than in the past. Both involve reducing blood pooling in the lower body by squeezing or flexing leg and abdomen muscles to restrict unwanted blood flow and pooling.&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-06-20T17:01:54.047" LastActivityDate="2014-06-20T17:01:54.047" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6413" PostTypeId="5" CreationDate="2014-06-20T17:23:52.143" Score="0" Body="" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-06-20T17:23:52.143" LastActivityDate="2014-06-20T17:23:52.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6414" PostTypeId="4" CreationDate="2014-06-20T17:23:52.143" Score="0" Body="A branch of engineering dealing with how humans interact with machines and systems. In aviation Human Factors engineering frequently deals with how pilots interact with aircraft systems and controls" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-06-20T17:23:52.143" LastActivityDate="2014-06-20T17:23:52.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6415" PostTypeId="2" ParentId="6398" CreationDate="2014-06-20T18:06:21.690" Score="3" Body="&lt;p&gt;The applicable US regulation is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=be6ffa6d87343c75e7d49e911c95ab06&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.11&amp;amp;idno=14#14:1.0.1.3.11.3&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 25.301-563&lt;/a&gt;. This obviously goes into a lot of detail about the different aspects that should be taken into account. I will try to condense the cases as much as possible, but many are conditional and relate to various other conditions. Many cases include some subjectivity as to what the FAA will require. Every certification is unique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the requirements are somewhat broken down into the general areas of the plane, it's impossible to say exactly which areas of the plane will be critically affected by a certain case. The impact depends on the design and configuration of the specific plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are the upper level requirements:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) The structure must be able to support limit loads without detrimental permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The structure must be able to support ultimate loads without failure for at least 3 seconds...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) The airplane must be designed to withstand any vibration and buffeting that might occur in any likely operating condition up to VD/MD, including stall and probable inadvertent excursions beyond the boundaries of the buffet onset envelope.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Definitions of various important values (which will have structural implications):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;V&lt;sub&gt;A&lt;/sub&gt; - Design maneuvering speed&lt;br/&gt;&#xA;V&lt;sub&gt;B&lt;/sub&gt; - Design speed for max gust intensity&lt;br/&gt;&#xA;V&lt;sub&gt;C&lt;/sub&gt; - Design cruising speed&lt;br/&gt;&#xA;V&lt;sub&gt;D&lt;/sub&gt; - Design dive speed&lt;br/&gt;&#xA;V&lt;sub&gt;DD&lt;/sub&gt; - Design drag device speeds&lt;br/&gt;&#xA;V&lt;sub&gt;F&lt;/sub&gt; - Desgin flap speeds&lt;br/&gt;&#xA;V&lt;sub&gt;MC&lt;/sub&gt; - Minimum control speed with critical engine inoperative&lt;br/&gt;&#xA;V&lt;sub&gt;S0&lt;/sub&gt; - Stall speed with landing flaps&lt;br/&gt;&#xA;V&lt;sub&gt;S1&lt;/sub&gt; - Stall speed, flaps retracted&lt;br/&gt;&#xA;C&lt;sub&gt;N&lt;/sub&gt; - Normal force coefficient&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All strength requirements must be met at all places within the maneuvering envelope, particularly A-I on the following V-n diagram:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vHiKD.png&quot; alt=&quot;V-n diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max pitch control deflection at V&lt;sub&gt;A&lt;/sub&gt; (25.331)&lt;/li&gt;&#xA;&lt;li&gt;Specified pitch control displacement (25.331)&lt;/li&gt;&#xA;&lt;li&gt;1.5g pullup (25.335)&lt;/li&gt;&#xA;&lt;li&gt;Discrete gust, vertical and lateral (25.341)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;V&lt;sub&gt;C&lt;/sub&gt;: varies linearly&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;+/- 56.0 ft/sec - sea level&lt;/li&gt;&#xA;&lt;li&gt;+/- 44.0 ft/sec - 15000 feet&lt;/li&gt;&#xA;&lt;li&gt;+/- 26.0 ft/sec - 50000 feet&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;D&lt;/sub&gt;: 0.5 times V&lt;sub&gt;C&lt;/sub&gt; values&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Continuous gust, vertical and lateral (25.341)&lt;/li&gt;&#xA;&lt;li&gt;Fuel/oil loads from zero to maximum (25.343)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Addtional factors if there is a &quot;structural reserve&quot; of fuel considered&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;High lift devices (25.345)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If flaps are to be used for takeoff, approach, or landing, limit load factor of 2.0&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;+/- 25 ft/sec normal to flight path&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Separate conditions, limit load factor of 1.0&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Propeller slipstream from max continuous power at V&lt;sub&gt;F&lt;/sub&gt;&lt;/li&gt;&#xA;&lt;li&gt;Propeller slipstream from takeoff power at &gt;= 1.4 times V&lt;sub&gt;F&lt;/sub&gt; and max weight&lt;/li&gt;&#xA;&lt;li&gt;Head-on gust of 25 ft/sec&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;If flaps are to be used en route:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maneuver to positive limit load factor&lt;/li&gt;&#xA;&lt;li&gt;Discrete vertical gusts&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Maneuver load factor of 1.5 g at max takeoff weight, flaps in landing configuration&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Roll maneuvering (25.349)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airplane load factor 0 and 2/3 of positive maneuvering factor&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Steady rolling velocities&lt;/li&gt;&#xA;&lt;li&gt;Maximum angular acceleration&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;A&lt;/sub&gt; Sudden deflection of aileron to the stop&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;C&lt;/sub&gt; Aileron deflection for same roll rate as V&lt;sub&gt;A&lt;/sub&gt; case&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;D&lt;/sub&gt; Aileron deflection for at least 1/3 of V&lt;sub&gt;A&lt;/sub&gt; case&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Unsymmetrical gusts&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Yaw maneuvering (25.351), speeds from V&lt;sub&gt;MC&lt;/sub&gt; to V&lt;sub&gt;D&lt;/sub&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sudden max rudder deflection (conditional definition)&lt;/li&gt;&#xA;&lt;li&gt;At that max deflection:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Yaw to overswing sideslip angle&lt;/li&gt;&#xA;&lt;li&gt;Yaw to static equilibrium sideslip angle&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rudder suddenly returned to neutral&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Engine torque (25.361)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limit engine torque at takeoff power and prop speed, 75% limit loads of V-n condition A&lt;/li&gt;&#xA;&lt;li&gt;Limit engine torque at max continuous power and prop speed, 100% limit loads at V-n condition A&lt;/li&gt;&#xA;&lt;li&gt;For turboprops, previous conditions with prop control system malfunction&lt;/li&gt;&#xA;&lt;li&gt;For turbine engines:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Torque from sudden engine stoppage&lt;/li&gt;&#xA;&lt;li&gt;Torque from max engine acceleration&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Engine/APU side loads (25.363)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limit side load factor&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Pressurized compartments (25.365)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;All flight loads in addition to pressure differential 0 to max relief valve setting&lt;/li&gt;&#xA;&lt;li&gt;External pressure distribution in flight&lt;/li&gt;&#xA;&lt;li&gt;Landing loads combine with max pressure allowed at landing&lt;/li&gt;&#xA;&lt;li&gt;Pressure including safety factor for high altitude aircraft (&gt;= 45,000 feet)&lt;/li&gt;&#xA;&lt;li&gt;Sudden release of pressure for critical components&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Also affects bulkheads, floors, and partitions&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Other emergency depressurizations&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Engine failure unsymmetrical loads (25.367)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Failure of critical engine (for turboprops, also failure of drag limiting system)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Speeds from V&lt;sub&gt;MC&lt;/sub&gt; to V&lt;sub&gt;D&lt;/sub&gt;, due to fuel flow interruption&lt;/li&gt;&#xA;&lt;li&gt;Speeds from V&lt;sub&gt;MC&lt;/sub&gt; to V&lt;sub&gt;C&lt;/sub&gt;, due to mechanical failure&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Includes pilot corrective action&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Gyroscopic loads (25.371)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Must be considered at max appropriate RPM for certain other cases&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Speed control devices (25.373)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Symmetrical and yaw maneuvers and gust conditions, each setting with max speed&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If automatic/load limiting features, include corresponding speeds/positions&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Control sufrace/system loads (25.391)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Considering other limit load cases&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Loads parallel to hinge line &lt;/li&gt;&#xA;&lt;li&gt;Pilot effort effects&lt;/li&gt;&#xA;&lt;li&gt;Trim tab effects&lt;/li&gt;&#xA;&lt;li&gt;Ground gust conditions&lt;/li&gt;&#xA;&lt;li&gt;Unsymmetrical loads&lt;/li&gt;&#xA;&lt;li&gt;Auxiliary aero surfaces&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Landing load condtions (25.473)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Descent at 10 fps, design landing weight&lt;/li&gt;&#xA;&lt;li&gt;Descent at 6 fps, design takeoff weight&lt;/li&gt;&#xA;&lt;li&gt;Both cases should be considered in the following cases:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Level landing&lt;/li&gt;&#xA;&lt;li&gt;Tail-down landing&lt;/li&gt;&#xA;&lt;li&gt;One-gear landing&lt;/li&gt;&#xA;&lt;li&gt;Side loads&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Rebound landing&lt;/li&gt;&#xA;&lt;li&gt;Ground handling&lt;/li&gt;&#xA;&lt;li&gt;Taxi, takeoff, landing roll&lt;/li&gt;&#xA;&lt;li&gt;Braked roll&lt;/li&gt;&#xA;&lt;li&gt;Turning&lt;/li&gt;&#xA;&lt;li&gt;Tail wheel yaw&lt;/li&gt;&#xA;&lt;li&gt;Nose wheel yaw/steering&lt;/li&gt;&#xA;&lt;li&gt;Pivoting&lt;/li&gt;&#xA;&lt;li&gt;Reversed braking&lt;/li&gt;&#xA;&lt;li&gt;Towing loads&lt;/li&gt;&#xA;&lt;li&gt;Unsymmetrical ground loads&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Seaplanes (25.521)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Step, bow, stern landings&lt;/li&gt;&#xA;&lt;li&gt;Unsymmetrical landing&lt;/li&gt;&#xA;&lt;li&gt;Hull/main float bottom pressures&lt;/li&gt;&#xA;&lt;li&gt;Auxiliary float loads&lt;/li&gt;&#xA;&lt;li&gt;Seawing loads&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Emergency landing (25.561)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Occupants must have reasonable chance of escaping serious injury in minor crash landing if occupant experiences the following forces:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Upward 3.0g&lt;/li&gt;&#xA;&lt;li&gt;Forward 9.0g&lt;/li&gt;&#xA;&lt;li&gt;Sideward 3.0g on airframe, 4.0g on seats&lt;/li&gt;&#xA;&lt;li&gt;Downward 6.0g&lt;/li&gt;&#xA;&lt;li&gt;Rearward 1.5g&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Large masses should not:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cause injury to occupants&lt;/li&gt;&#xA;&lt;li&gt;Penetrate fuel tanks&lt;/li&gt;&#xA;&lt;li&gt;Block escape&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Protection of occupants in dynamic conditions&lt;/li&gt;&#xA;&lt;li&gt;Ditching strength&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Fatigue and damage tolerance (25.571)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Residual strength with certain failed structure:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limit symmetrical maneuvers&lt;/li&gt;&#xA;&lt;li&gt;Limit gust conditions&lt;/li&gt;&#xA;&lt;li&gt;Limit rolling conditions&lt;/li&gt;&#xA;&lt;li&gt;Limit yaw conditions&lt;/li&gt;&#xA;&lt;li&gt;Pressure differentials&lt;/li&gt;&#xA;&lt;li&gt;Limit ground loads&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Safe-life evaluation, if failure conditions are not practical&lt;/li&gt;&#xA;&lt;li&gt;Sonic fatigue&lt;/li&gt;&#xA;&lt;li&gt;Safe flight with damage from:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;4 pound bird at V&lt;sub&gt;C&lt;/sub&gt; at sea level and 0.85V&lt;sub&gt;C&lt;/sub&gt; at 8,000 feet&lt;/li&gt;&#xA;&lt;li&gt;Uncontained fan blade impact&lt;/li&gt;&#xA;&lt;li&gt;Uncontained engine failure&lt;/li&gt;&#xA;&lt;li&gt;Uncontained high-energy rotating machinery failure&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-20T18:16:24.350" LastActivityDate="2014-06-20T18:16:24.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6416" PostTypeId="1" AcceptedAnswerId="6417" CreationDate="2014-06-20T18:13:16.687" Score="18" ViewCount="2794" Body="&lt;p&gt;If a twin-engine aircraft has an engine problem and could fly somewhere for maintenance, is a single-engine ferry flight ever allowed? If so, do airlines or pilots ever decide to do this?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="97" LastEditDate="2014-06-20T21:38:43.580" LastActivityDate="2014-06-21T10:34:08.707" Title="Is a single-engine ferry flight allowed with a twin-engine plane?" Tags="&lt;safety&gt;&lt;engine&gt;&lt;ferry-flight&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6417" PostTypeId="2" ParentId="6416" CreationDate="2014-06-20T19:30:49.060" Score="14" Body="&lt;p&gt;I can find no evidence of the FAA or any other authority ever issuing such a permit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/AviationQuery/brief.aspx?ev_id=20001211X09774&amp;amp;key=1&quot;&gt;It has happened, though&lt;/a&gt; (without a permit). An SN-601 tried to take off from Portland with one engine. Unsuccessfully. Luckily no one was hurt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also a &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/286524/&quot;&gt;lengthy thread about it on airliners.net&lt;/a&gt;, in which there are several undocumented, anecdotal stories about this being done successfully (and illegally), e.g. in a &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_P-38_Lightning&quot;&gt;P-38&lt;/a&gt; and either a &lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_CV-240&quot;&gt;Convair 240 or 600&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some good technical reasons why this is unlikely to be safe, or approved by any authority:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Asymmetric thrust will make the takeoff very difficult. In particular, until the airplane reaches V&lt;sub&gt;MC&lt;/sub&gt;, it may not be possible to keep the airplane on the centerline with takeoff thrust on one engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Especially for piston airplanes, single-engine performance is often very poor. Hence the expression, &quot;in the event of an engine failure, the other engine will get you to the scene of the crash.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;All-engines-out operation in a multi-engine airliner is usually considered an extremely unlikely event, and as such, training is patchy and contingency procedures are very dire if they exist at all. Basically, if your one good engine dies, you'd be in mortal danger, much moreso than in a single-engine airplane, in which pilots are well trained for engine failures, since all-engines-out is a much more likely event.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Back to the notion of ferry permits, some guidance is given in &lt;a href=&quot;http://www.risingup.com/fars/info/part91-611-FAR.shtml&quot;&gt;14 CFR §91.611&lt;/a&gt;, which lays out conditions for one-engine-inoperative ferry permits for 4-engine or 3-engine-turbine airplanes. It says nothing about twins though.&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2014-06-20T19:30:49.060" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="6418" PostTypeId="2" ParentId="6411" CreationDate="2014-06-20T20:03:52.313" Score="13" Body="&lt;p&gt;The prone position was researched a lot in Germany before anti-g suits were invented. The human body can tolerate g loads a lot better lying than sitting. Martin Eiband collected a lot of data on this, if you want to know more, google for &quot;Eiband diagrams&quot;. If you want the full picture, read the &lt;a href=&quot;http://www.aero.polimi.it/~anghi/bacheca_sp/materiale_didattico/ACSDG_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;Army Aircraft Crash Survival Guide&lt;/a&gt;. It comes in five volumes, and volume 1 covers the design criteria. The Eiband diagrams below are lifted from this source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GU9WM.jpg&quot; alt=&quot;Eiband diagram for lying human&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frontal acceleration is quite similar to that of the lying pilot. Please note that for a duration of 0.1 seconds, the limit is 40 g! For 1 full second, this goes down to 10 g. Any more, and the pilot might show mild symptoms of stress. And if you go up to approx. 23 g for 1 second (logarithmic scale!), there is a risk of serious injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FKebg.png&quot; alt=&quot;Eiband diagram for sitting human&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This diagram shows the limits for a sitting human. At 0.1 seconds, the limit is only 10 g. For a full second, this goes down to 5 g, even though the data does not cover this duration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One notable research plane was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Akaflieg_Berlin_B_9&quot; rel=&quot;noreferrer&quot;&gt;B-9&lt;/a&gt;, built by Akaflieg Berlin, a student group which designed and built airplanes during their time at Berlin's Technical University. This airplane was designed for 22 g and used a prone position for the single pilot. It was tested in 1943 and proved the validity of the concept. Previously, Akaflieg Stuttgart had built the fs-17 for the same purpose. Also, the Horten flying wing gliders were flown in a kneeling-prone position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bHzaD.jpg&quot; alt=&quot;Horten IV pilot position&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horten IV pilot position. Note the chin rest!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was even a ground attack aircraft designed for a prone position, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Henschel_Hs_132&quot; rel=&quot;noreferrer&quot;&gt;Henschel 132&lt;/a&gt;, a small, jet-powered single seater. A prototype was almost finished before the war ended, and it never was used operationally. Similarly, a rocket-powered, glider-like high altitude reconnaissance plane, the &lt;a href=&quot;http://en.wikipedia.org/wiki/DFS_228&quot; rel=&quot;noreferrer&quot;&gt;DFS-228&lt;/a&gt;, was only flown without the rocket engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The prone position has a major disadvantage: Visibility is poor where it counts most. Downward visibility is great, and even forward visibility can be considered acceptable, but especially in turns the pilot must be able to look up. A tight turn is mostly a horizontal looping, and a lying pilot needs to lift his head up against the g forces in a turn - this is extremely tiring! The whole concept is impossible for air combat, where g forces are highest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The prone position has an advantage for small aircraft where the drag of a sitting pilot would be unacceptable. It has only found widespread use in hang gliding, but all other aircraft prefer a sitting or, mostly in gliders, a backwards lying pilot.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T19:50:09.403" LastActivityDate="2015-05-07T19:50:09.403" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="6419" PostTypeId="2" ParentId="6416" CreationDate="2014-06-20T20:34:15.987" Score="15" Body="&lt;p&gt;Civilian aircraft are not designed for this - but some military aircraft are. The Antonov-70 can easily take off with one engine inoperational (it has four in total), but it has a limited capability to take off with &lt;strong&gt;two&lt;/strong&gt; engines out on the &lt;strong&gt;same&lt;/strong&gt; side! For that, it has to be empty and can carry only minimum fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0U3Ug.jpg&quot; alt=&quot;An-70 at Paris Airshow in 2000&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This capability is the consequence of the demand of the Soviet Air Force for the An-70 to operate for 6 months with minimum maintenance. The Antonov design bureau, well aware of the limited capabilities of front-line troops in aircraft maintenance, designed this transporter with lots of redundancy.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit:&#xA;With one engine inoperational, any twin-engined civilian aircraft would not be legal if it attempted a one-engine take-off. I would expect there is a way to do it, but it needs the agreement of the owner and some paperwork with the local authorities. If you can prove that this particular ferry flight is safe, I think you would be allowed to fly. But I am certain that without lengthy preparation and paperwork there is no way to &lt;strong&gt;legally&lt;/strong&gt; take off on one engine only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is in contrast to military aviation where this kind of operation is planned for.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-21T10:34:08.707" LastActivityDate="2014-06-21T10:34:08.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="6420" PostTypeId="1" AcceptedAnswerId="7421" CreationDate="2014-06-20T23:35:02.220" Score="25" ViewCount="19733" Body="&lt;p&gt;When a plane crashes in the water and the investigator team looks for the FDR and CVR, why do they put it in a container of water when they find it ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xTrxU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xTrxU.jpg&quot; alt=&quot;img&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="161" LastEditorUserId="22550" LastEditDate="2018-11-28T03:41:05.807" LastActivityDate="2018-11-28T03:41:05.807" Title="Why is the FDR and CVR put into water again after a water crash?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;ntsb&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7420" PostTypeId="2" ParentId="6420" CreationDate="2014-06-21T01:18:45.733" Score="8" Body="&lt;p&gt;After being sunk in water, especially salt water, the devices are more susceptible to corrosion when removed from the water. In order to better ensure a successful recovery of the data contained within, the investigators keep them immersed in water until they can be properly cleaned and dried in a laboratory. If they were to be simply removed into the air, corrosion would begin immediately, increasing the odds of data loss.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-06-21T01:18:45.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7421" PostTypeId="2" ParentId="6420" CreationDate="2014-06-21T01:18:54.183" Score="40" Body="&lt;p&gt;This is actually a fairly standard thing to do with electronics that have been submerged: They are placed in water (ideally fresh, clean water) to both delay the onset of corrosion and dilute any salts or other chemicals that they came in contact with while submerged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you remove electronics from water and let them dry out they begin to form corrosion on all the little exposed bits of metal - chip legs, solder joints, capacitors, etc. - which can badly damage the device when it is powered back on.&lt;br&gt;&#xA;Keeping the device submerged in water delays the onset of this corrosion because the dissolved oxygen in the water is lower than the oxygen in the air that would be hitting those parts as they dry out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cockpit Voice Recorder and Flight Data Recorder are water resistant, but they are not necessarily &lt;em&gt;waterproof&lt;/em&gt; (particularly after a crash, which may puncture their casings or damage seals), so they get placed in a container of fresh water for their trip to the NTSB's lab.&lt;br&gt;&#xA;When the still-immersed equipment arrives at the NTSB laboratory it can be examined and dried in a controlled environment, maximizing the chance to recover data.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For more gory details check out &lt;a href=&quot;http://www.ntsb.gov/investigations/process/Documents/FDR_Handbook.pdf&quot;&gt;The NTSB Flight Data Recorder Handbook for Aviation Accident Investigations&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Bonus Factoid: Archaeological recoveries from bodies of water use similar procedures, for similar reasons: If you bring up a clay pot that's been sitting at the bottom of a lake for a thousand years and let it air-dry naturally there's a good chance it will crack and be destroyed.&lt;br&gt;&#xA;In archaeological recoveries the usual practice is to keep the item &quot;waterlogged, ideally in waters associated with the original context&quot; (i.e. &quot;in a bucket of water from where you got the thing&quot;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="7434" LastEditDate="2015-02-26T03:15:48.647" LastActivityDate="2015-02-26T03:15:48.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7422" PostTypeId="2" ParentId="6416" CreationDate="2014-06-21T01:40:57.360" Score="3" Body="&lt;p&gt;Large aircraft with huge power reserves probably &lt;em&gt;could&lt;/em&gt;, assuming you can find a pilot willing to do it. A twin-engine fighter like an F-18 very likely can - the single-engine thrust-to-weight ratio is nearly double that of a 777, and if you light the afterburner it has more thrust on one engine than a 777 with both mills turning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller piston twins usually cannot - one engine is not enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crash rate for light piston twins is (or used to be) much higher than that of piston singles. The reason: the asymmetric thrust made them much harder to control to the point where the occasional instructor said &quot;if one engine goes, feather the other one too&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One notable example is the Cessna Skymaster - two engines, centerline thrust. notable enough that the FAA created a multi-engine license category just for it. Common accident mode in the Skymaster is feathering the wrong engine in-flight, and the number of takeoff failures with the back engine &lt;strong&gt;not running&lt;/strong&gt; says it won't take off on just one either. Maybe if you removed the prop, no passengers, minimum fuel and a really long runway. Check your life insurance first.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-21T01:40:57.360" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7423" PostTypeId="2" ParentId="1106" CreationDate="2014-06-21T05:29:44.700" Score="20" Body="&lt;p&gt;The Messerschmitt Me-262 had nose wheel braking as well. Back then, with the high landing speed of jets and no thrust reversers, the engineers wanted to give pilots as much stopping power as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture which shows the brake line running down to the wheel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OEddc.jpg&quot; alt=&quot;Abandoned Me-262 after the war&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Abandoned Me-262 after the war (picture &lt;a href=&quot;http://albumwar2.com/disassembled-messerschmitt-me-262-at-the-airport-in-frankfurt/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2018-01-17T21:47:21.210" LastActivityDate="2018-01-17T21:47:21.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7425" PostTypeId="2" ParentId="700" CreationDate="2014-06-21T11:10:35.947" Score="38" Body="&lt;p&gt;Torque is less of a problem due to the effective roll damping of a wing, but gyro effects and prop wash are important. Gyro effects first became an issue with rotary engines in WW I. A rotary engine has its crankshaft fixed to the airplane, and both the cylinder block and the propeller rotate. This gives better cooling at low speed and produces a flywheel effect, so the engine runs more smoothly. But when you yaw, the gyro effect pitches the aircraft up or down, so any precise maneuvering becomes very hard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the increasing engine power in 1916 and 1917, this effect became so severe that geared engines were developed where the cylinders rotate in one direction and the propeller in the opposite direction. As a consequence, the propeller had only half the RPM in air as it had with the cylinder block. This gave great propeller efficiency, but also big propeller diameters, so airplanes with those engines needed a high landing gear. Below is a picture of a Roland D XVI with a &lt;a href=&quot;http://en.wikipedia.org/wiki/Siemens-Halske_Sh.III&quot; rel=&quot;noreferrer&quot;&gt;Siemens &amp;amp; Halske III&lt;/a&gt; counter-rotating rotary engine from 1918 (&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/LFG_Roland_D.XVI_first_prototype.jpg/1024px-LFG_Roland_D.XVI_first_prototype.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). This was an excellent fighter aircraft for its time with almost no gyro coupling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JsJnM.jpg&quot; alt=&quot;Roland D XVI&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, high power propeller aircraft tend to use identical engines but left- and right-handed gearboxes so the propellers run in both directions. This is less due to gyro effects and mostly to produce benign stall characteristics. The prop wash of a propeller increases the local angle of attack on the wing on one side and decreases it on the other side, so the wing will stall first on the side with bigger angle of attack. If this side is always to the right of the propellers, the aircraft will roll right in a stall. In the WW II period, a number of multi-engined aircraft used left-hand and right-hand turning engines in order to have the prop wash cancel out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With jets, the rotating inertias are much smaller because the diameters are smaller. But there is one exception: The &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Pegasus&quot; rel=&quot;noreferrer&quot;&gt;Bristol-Siddeley Pegasus&lt;/a&gt; engine of the Kestrel, Harrier and AV-8B jump jets needs to have the low pressure spool run in opposite direction of the high pressure spool to balance its gyro effects. If that would not be the case, a yawing motion would produce a pitching motion, and vice versa. When you sit on a jet, the thrust of which is equivalent to your weight, tilting this jet fore or aft only slightly will produce a quick shift of your location, so any maneuvering in hover will become extremely hard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9aYva.jpg&quot; alt=&quot;USMC AV-8B Harrier in hover&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;USMC AV-8B Harrier in hover (picture &lt;a href=&quot;http://www.hangar25airmuseum.org/images/harrier_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-09-27T22:31:57.353" LastActivityDate="2017-09-27T22:31:57.353" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7426" PostTypeId="1" CreationDate="2014-06-21T14:20:21.513" Score="11" ViewCount="794" Body="&lt;p&gt;I saw my first UAV last night as it followed me up the street in Lancaster, PA. Does anyone know what type of unit this is or who would own one? I am guessing it was the police? I am curious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cCUC3.jpg&quot; alt=&quot;Mystery UAV&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2662" LastEditorUserId="790" LastEditDate="2014-06-21T17:23:25.390" LastActivityDate="2014-06-21T17:23:25.390" Title="What is this object that followed me up the street?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7427" PostTypeId="2" ParentId="7426" CreationDate="2014-06-21T14:39:31.067" Score="11" Body="&lt;p&gt;This is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Quadcopter&quot;&gt;quadcopter&lt;/a&gt;, so called because it uses four rotors to generate lift. They are now made cheaply in China and can be purchased in most technology-related online shops. They are remotely controlled, so it is safe to assume that the owner was close, but not in plain view. It might have been the police, but it could as well be a hobbyist, taking his new toy out for a spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since most units are equipped with a cheap webcam and a wireless link, I would guess he/she was sitting in front of a computer or using his/her smartphone for controlling the device and watching the camera stream.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-06-21T14:39:31.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7428" PostTypeId="1" AcceptedAnswerId="7429" CreationDate="2014-06-21T22:40:34.903" Score="17" ViewCount="2990" Body="&lt;p&gt;A couple of months back I was going on a road trip through California and stopped by a dry lake called &lt;a href=&quot;https://en.wikipedia.org/wiki/El_Mirage_Lake&quot;&gt;El Mirage Lake&lt;/a&gt;. It's a very tacky area requiring a permit to enter.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My friend and I showed up near midnight and could hear a VERY low-flying aircraft. I happened to have a flashlight with a 800&amp;nbsp;m beam distance and using it we could clearly see a &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Atomics_MQ-1_Predator&quot;&gt;Predator drone&lt;/a&gt; less than 500 feet over the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drone was flying an autonomous rectangular course over the lake all night, but the next morning it had changed altitude and was flying a few thousand feet over the lake - high enough that it just looked like a normal airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For 30 minutes or so there was a &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna#Aircraft_models&quot;&gt;Cessna&lt;/a&gt; following behind it which was very strange... Would it be a human monitoring the drone for some reason?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, as a current civilian I feel like there's something wrong with military aircraft being used as surveillance over public area, not to mention it seems a little pointless. Why is the government (or at least state of California) using equipment like this for useless reasons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a pretty bad photo of it using a telephoto lens that I can post later as proof that is was actually a Predator drone. &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="19" LastEditDate="2017-01-09T11:07:21.567" LastActivityDate="2017-01-09T11:07:21.567" Title="Why are predator drones being used over civilian California?" Tags="&lt;military&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7429" PostTypeId="2" ParentId="7428" CreationDate="2014-06-21T22:51:38.397" Score="33" Body="&lt;p&gt;An article from 2001, &lt;a href=&quot;http://www.thefreelibrary.com/TESTING+SPY+PLANES+GRAY+BUTTE+AIRFIELD+TO+BE+REOPENED.-a083599060&quot;&gt;TESTING SPY PLANES GRAY BUTTE AIRFIELD TO BE REOPENED&lt;/a&gt; says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;General Atomics, which makes the Predator in San Diego, has been conducting final production tests and checkout flights at El Mirage, three miles inside the San Bernardino County line.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://clui.org/ludb/site/el-mirage-flight-test-facility&quot;&gt;EL MIRAGE FLIGHT TEST FACILITY&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="556" LastActivityDate="2014-06-21T22:51:38.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7430" PostTypeId="1" AcceptedAnswerId="7432" CreationDate="2014-06-21T23:37:37.520" Score="21" ViewCount="39579" Body="&lt;p&gt;Over in &lt;a href=&quot;https://aviation.stackexchange.com/a/5022&quot;&gt;this answer&lt;/a&gt; there's a description of Hobbs Time versus Tach Time, and how the Hobbs counts hours while the tach time is equivalent to &quot;hours at cruise RPM&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do these two &quot;clocks&quot; work, and what do these numbers mean in practical terms for flying and maintaining an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2018-04-09T17:31:41.333" Title="What is the difference between Hobbs Time and Tach Time?" Tags="&lt;aircraft-maintenance&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7432" PostTypeId="2" ParentId="7430" CreationDate="2014-06-22T02:14:51.453" Score="16" Body="&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Hobbs_meter&quot; rel=&quot;noreferrer&quot;&gt;Hobbs Time&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most planes, the Hobbs clock is started and stopped based on an oil pressure switch, so it starts when the engine starts, and stops when the engine is shut-down. While it's running, it just ticks off a tenth of an hour every 6 minutes, based on &quot;regular wall clock time&quot;. So a tenth of idling on the ramp is the same as a tenth at cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Tach_Timer&quot; rel=&quot;noreferrer&quot;&gt;Tach Time&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tach clock isn't really a clock at all, it doesn't actually measure time, it really measures engine revolutions. But it's calibrated such that a tenth of an hour of tach time is clicked off when the engine is at cruise RPM for 6 minutes. In other words, if the plane is at cruise RPM, the tach clock will be clicking off tenths of an hour at the same rate as the Hobbs clock, and the same as the watch on your wrist. But if the engine is idling at an RPM speed that's half of what cruise RPM is, then the tach clock will be running at half the speed of the Hobbs clock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Relation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, for the tach clock, less &quot;time&quot; is clocked when the plane is idling on the ramp, or flying at low RPM. For short flights (where ramp idling time is a significant percentage of total time), and flights where you're doing a lot of pattern work (and thus operating at low RPM), tach time will be significantly less than Hobbs time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Maintenance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an engine is replaced or overhauled, that engine is considered to be &quot;zero time&quot;. Whether they actually reset the tach gauge to 0 when the engine is overhauled, or if there's a way to put a time on a brand new tach or Hobbs meter when the old one dies and is replaced, I dunno, but in general, I'd assume that the aircraft's engine and airframe log books are really the official recording of the progression of airframe/engine times, so I don't know that it's particularly important whether the tach is set to the engine's time, or if it's really just used as an incremental meter.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;AOPA has a nice (and long) &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/2013/may/flight-training-magazine/time-is-money&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt; about this.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="26946" LastEditDate="2018-04-09T17:31:41.333" LastActivityDate="2018-04-09T17:31:41.333" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7433" PostTypeId="2" ParentId="7428" CreationDate="2014-06-22T09:38:38.837" Score="18" Body="&lt;p&gt;ChrisW's answer covers &quot;why the Predator?&quot; (&lt;a href=&quot;https://en.wikipedia.org/wiki/El_Mirage_Field&quot;&gt;El Mirage Field&lt;/a&gt; is used by General Atomics for test-flying their drones), which makes &quot;Why the Cessna?&quot; easy to answer: if General Atomics is test-flying a Predator drone or variant, the Cessna is probably there as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Chase_plane&quot;&gt;chase plane&lt;/a&gt; to monitor the test.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-06-22T09:38:38.837" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7437" PostTypeId="1" CreationDate="2014-06-22T15:30:52.660" Score="11" ViewCount="7986" Body="&lt;p&gt;If a 777 pilot wanted to fly further than with both engines running, how many more miles could the plane go with just one engine running, at high altitude? &lt;/p&gt;&#xA;" OwnerUserId="2667" LastEditorDisplayName="user2168" LastEditDate="2014-06-23T00:33:47.777" LastActivityDate="2019-02-23T20:22:25.847" Title="How far can a 777 fly with just one engine at altitude?" Tags="&lt;engine&gt;&lt;boeing-777&gt;&lt;range&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7438" PostTypeId="2" ParentId="7437" CreationDate="2014-06-22T15:50:32.387" Score="26" Body="&lt;p&gt;Flying with only one of two engines will not increase range, but reduce it. A gas turbine consumes fuel in proportion to the mass of air moving through it, so with increasing altitude consumption decreases proportional with air density. Thrust goes down with density as well, so thrust-specific fuel consumption is roughly constant (actually, the engine becomes &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;more efficient with altitude&lt;/a&gt; due to the lower air temperature, see &lt;a href=&quot;http://en.wikipedia.org/wiki/Carnot_cycle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carnot cycle&lt;/a&gt; for more on that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, a jet transport wants to fly as high as possible for maximum range. Its cruise altitude is limited mainly by the thrust available from all engines. If the pilot shuts one down, the aircraft needs to fly much lower until thrust has increased sufficiently to overcome drag. Since friction drag is also proportional to air density (and the square of flight speed), the aircraft has to fly much slower at that lower altitude, which cuts range since the fuel consumption of the single engine is now roughly what both consumed at altitude, but now the aircraft covers less distance in the same time. In addition, the pilot has to compensate asymmetric thrust with rudder deflection, which again increases drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer: The aircraft will not go MORE miles, but FEWER.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-02-23T20:22:25.847" LastActivityDate="2019-02-23T20:22:25.847" CommentCount="15" ContentLicense="CC BY-SA 4.0" />
  <row Id="7440" PostTypeId="1" AcceptedAnswerId="7450" CreationDate="2014-06-22T18:27:05.263" Score="3" ViewCount="795" Body="&lt;p&gt;The wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Quadcopter#Flight_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Quadcopter&lt;/a&gt; entry provides some details about its flight control:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EwB9r.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Hovering or altitude adjustement.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZwBTT.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Pitch or roll  adjustment.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jw2sN.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Yaw adjustement.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The following post &quot;&lt;a href=&quot;https://aviation.stackexchange.com/q/1830/247&quot;&gt;Quadcopter flight modes beyond traditional aircraft?&lt;/a&gt;&quot; raised to my attention that it had &lt;strong&gt;other flight modes&lt;/strong&gt; apart from those of fixed wing aircraft but I am not so sure with respect to conventional rotorcraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Question:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;My assumption is that the quadcopter can be flown using conventional helicopter flight control inputs (cyclic, collective, anti-torque, throttle), am I right or is it really another beast with its very own flight control inputs?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="15311" LastEditDate="2017-11-17T16:45:07.307" LastActivityDate="2017-11-17T17:14:57.720" Title="Is multi/quadcopter flight control similar to helicopters?" Tags="&lt;flight-controls&gt;&lt;unmanned-aerial-vehicle&gt;&lt;rotorcraft&gt;&lt;quadcopter&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7441" PostTypeId="5" CreationDate="2014-06-22T18:41:34.363" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-06-22T18:41:34.363" LastActivityDate="2014-06-22T18:41:34.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7442" PostTypeId="4" CreationDate="2014-06-22T18:41:34.363" Score="0" Body="An unmanned aerial vehicle (UAV) is an aircraft without a human pilot aboard." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-06-22T19:43:17.920" LastActivityDate="2014-06-22T19:43:17.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7443" PostTypeId="2" ParentId="3300" CreationDate="2014-06-22T19:11:38.060" Score="19" Body="&lt;p&gt;&lt;a href=&quot;https://www.advancedtacticsinc.com/&quot; rel=&quot;noreferrer&quot;&gt;Advanced Tactics&lt;/a&gt; has also somewhat did it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YAN0f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://youtu.be/kDay5OWDPn4&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt; of the first flight of the &lt;strong&gt;Black Knight Transformer&lt;/strong&gt; has been released on Youtube.&lt;/p&gt;&#xA;" OwnerUserId="247" LastActivityDate="2014-06-22T19:11:38.060" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7444" PostTypeId="1" AcceptedAnswerId="9929" CreationDate="2014-06-23T01:47:31.270" Score="20" ViewCount="5939" Body="&lt;p&gt;I was reading an article about drones and happened to glance at an included 3-view of the General Atomics Predator series UAV. The inverted-V tail appears to leave, at most, around 6&quot; of clearance to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vTa12.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On takeoff or landing, how is there enough clearance to allow the operator to rotate? Is the wing designed to have a high angle of incidence on the ground?&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-02T18:30:37.013" Title="Does the Predator drone's design make a tail strike more likely on takeoff and landing?" Tags="&lt;aircraft-design&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7445" PostTypeId="2" ParentId="7444" CreationDate="2014-06-23T02:29:59.223" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;On takeoff or landing, how is there enough clearance to allow the operator to rotate?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Predator just doesn't rotate enough to hit the tail: See &lt;a href=&quot;https://www.youtube.com/watch?v=rBDq264OH0E&amp;amp;t=61s&quot;&gt;this takeoff video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;https://www.youtube.com/watch?v=rBDq264OH0E&amp;amp;t=180s&quot;&gt;it lands very flat&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drawing in your question shows that there is 5.3° of rotation angle before tailstrike occurs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, from the drawing, the angle of incidence doesn't look remarkable.&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorDisplayName="user2168" LastEditDate="2014-06-23T02:38:33.223" LastActivityDate="2014-06-23T02:38:33.223" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7446" PostTypeId="1" CreationDate="2014-06-23T05:51:07.217" Score="6" ViewCount="1838" Body="&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Is it legal to fly a drone with a go pro or something and take photos and video for commercial purposes? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what I found on the FAA website.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All UAS operations for commercial or business purposes are subject to FAA regulation. At a minimum, any such flights require a certified aircraft and a certificated pilot. UAS operations for commercial or business purposes cannot be operated under the special rule for model aircraft found in section 336 of Public Law 112-95.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/initiatives/uas/uas_faq/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/about/initiatives/uas/uas_faq/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many news articles say that the FAA will not really care.&lt;/p&gt;&#xA;" OwnerUserId="2672" LastEditorUserId="790" LastEditDate="2014-06-23T08:55:55.763" LastActivityDate="2017-10-23T23:20:12.700" Title="Is it legal to use RC quadcopters for commercial purposes?" Tags="&lt;faa-regulations&gt;&lt;commercial-operations&gt;&lt;rc-aircraft&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7447" PostTypeId="2" ParentId="7446" CreationDate="2014-06-23T08:07:33.653" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is it legal to fly a drone with a go pro or something and take photos and video for commercial purposes?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wired.co.uk/news/archive/2014-02/20/shoot-down-drones&quot; rel=&quot;nofollow&quot;&gt;Yes, many news businesses think so&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the numbers of drones &lt;strong&gt;licensed for commercial flights&lt;/strong&gt; by the nation's Civil Aviation Authority (CAA), which regulates the use of unmanned flying aircraft, shoots up -- from 30 in January 2013 to more than 300 today&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Many news articles say that the FAA will not really care.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most drone operators will not care too much what the FAA thinks. This is because the FAA don't have authority over most drone operations. This is mainly because they only really have authority in one country in one part of one continent. The FAA won't be arresting Mr 王 in 中国.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read what the &lt;a href=&quot;http://www.faa.gov/news/updates/?newsId=76240&quot; rel=&quot;nofollow&quot;&gt;FAA says about Unmanned aircraft&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the FAA discovers apparent unauthorized UAS operations, the agency has a number of enforcement tools available to address these operations, including a verbal warning, a warning letter, and an order to stop the operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which suggests the FAA cares, at least about commercial UAS operations in the northern parts of the continent of America which aren't Canada or Mexico.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also have a &lt;a href=&quot;http://www.faa.gov/about/initiatives/uas/uas_faq/&quot; rel=&quot;nofollow&quot;&gt;FAQ&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All UAS operations for commercial or business purposes are subject to FAA regulation. At a minimum, any &lt;strong&gt;such flights require a certified aircraft and a certificated pilot&lt;/strong&gt;. UAS operations for commercial or business purposes cannot be operated under the special rule for model aircraft found in section 336 of Public Law 112-95.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-23T09:00:11.467" LastActivityDate="2014-06-23T09:00:11.467" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7450" PostTypeId="2" ParentId="7440" CreationDate="2014-06-23T14:59:01.337" Score="5" Body="&lt;p&gt;As  commented, a quadcopter is generally flown by a computer. Given command inputs, the computer controls the speed of the four rotors, as shown in the images included in the question. The four rotors give the quadcopter a wide range of maneuverability. This is why quadcopters are currently used in many research applications. They can simulate conventional fixed-wing flight, helicopter flight, or something completely different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A quadcopter could certainly be flown with conventional helicopter controls. The four rotors allow it to be controlled by a cyclic, and the differential rotor torque allows it to be controlled by the anti-torque controls. However, unlike most helicopters, most quadcopters have fixed-pitch rotors. This is probably mainly due to size and cost constraints. The small size of quadcopters, combined with the lift being distributed among four rotors, allows each rotor to be smaller and much more resposive with RPM than a large rotor. This means that instead of collective and throttle, most quadcopters will only have throttle. Controlling the speed if the individual rotors is the end-result of their control algorithms.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-23T14:59:01.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7451" PostTypeId="1" AcceptedAnswerId="7454" CreationDate="2014-06-23T15:01:30.203" Score="14" ViewCount="9874" Body="&lt;p&gt;The &quot;area rule&quot; states that the supersonic drag on an aircraft is related to the total area on part of the aircraft. What is the exact definition of the rule? Why does this happen?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2018-05-16T17:23:12.130" Title="What is the &quot;area rule&quot;?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7452" PostTypeId="1" AcceptedAnswerId="7455" CreationDate="2014-06-23T15:23:51.380" Score="27" ViewCount="6676" Body="&lt;p&gt;I have read people's stories that they landed their small planes (e.g. C172) on bigger airports. They strongly recommended landing at a higher speed and without flaps as the runways are quite long, and there is traffic behind them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, if I want to land &lt;em&gt;an&lt;/em&gt; airplane at higher than recommended landing speed (e.g. V&lt;sub&gt;S&lt;sub&gt;0&lt;/sub&gt;&lt;/sub&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How fast can I go?&lt;/li&gt;&#xA;&lt;li&gt;What is the procedure to do this?&lt;/li&gt;&#xA;&lt;li&gt;What consequences are there (good or bad)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="65" LastEditorUserId="289" LastEditDate="2014-06-23T17:07:48.407" LastActivityDate="2015-06-11T04:23:55.907" Title="At what speeds can an airplane land?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;aircraft-limitations&gt;" AnswerCount="6" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7453" PostTypeId="2" ParentId="7452" CreationDate="2014-06-23T16:37:40.200" Score="27" Body="&lt;p&gt;Note: Much of this material, and more, is also covered in answers to the question:&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/751/can-you-fly-a-light-ga-airplane-into-a-major-hub-what-operational-consideration&quot;&gt;Can you fly a light GA airplane into a major hub?&lt;/a&gt; (Didn't know that at the time I wrote this answer.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Landing at higher than normal speed is &lt;strong&gt;not&lt;/strong&gt; recommended.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Tricycle gear airplanes require a nose-high attitude on touchdown in order to ensure the main gear touch down first. The nose gear is not designed to support initial touchdown forces. In many typical small planes, forcing the plane onto the ground at too high a speed will strike the nose wheel first, risking a collapse or prop strike.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At high speed, the control surfaces and wings are still capable of producing significant aerodynamic forces. If you've forced your wheels onto the ground, you may be producing a lot of torque with the elevator, again, risking gear collapse.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Kinetic energy is proportional to the &lt;em&gt;square&lt;/em&gt; of your velocity.&lt;/strong&gt; And crash damage -- both to the airplane and to its passengers -- is proportional to energy. If you do collapse the gear or lose control, you're going to have a lot more energy to dissipate. And if that energy is dissipated by your body, it's going to hurt. A lot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You might overheat your brakes, causing brake pad/rotor damage or even a fire (I'm aware of at least one instance of a Piper Cherokee catching on fire because the pilot attempted to take off with a half-stuck parking brake.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is true that you will sometimes be pressured by controllers at large airports to keep your speed up as much as possible on approach. It's hard for them to sequence you when you're only flying half as fast as the guys in front of and behind you. The important thing to remember is that &lt;strong&gt;this is their problem, not yours&lt;/strong&gt;. There's no FAR that says you must hot dog your airplane in order to fit in with the big boys.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some things you &lt;strong&gt;can&lt;/strong&gt; do safely to make everyone's job easier when operating at large/busy airports:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Practice your controlled-airport/airspace proficiency.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Know, and use, standard ATC phraseology.&lt;/li&gt;&#xA;&lt;li&gt;Listen carefully for your callsign. Don't make them repeat themseleves.&lt;/li&gt;&#xA;&lt;li&gt;Have a plan in advance, know what you want, and make sure you communicate that to them clearly.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Have the airport diagram handy, and study it before the flight so you know where you'll be taxiing and won't mess up ground operations. Ideally you should be able to taxi on your own, but if you're not comfortable when you get your taxi instructions, &lt;strong&gt;request a progressive taxi&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Know your airplane and its capabilities. Fly your approach at the highest practical speed, but &lt;strong&gt;no faster&lt;/strong&gt;. Know how fast you can go on a 3 mile final in order to be able to decelerate to normal short-final and touchdown speeds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you're not comfortable with your proficiency in these areas, consider getting some more practice before attempting a flight to a &quot;major&quot; airport. Or, bring a CFI along with you who can help you out and give you pointers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bottom line is &lt;strong&gt;under no circumstances should you compromise safety in order to please ATC or the airline pilot behind you&lt;/strong&gt;. As long as you are &lt;strong&gt;proficient&lt;/strong&gt; and do your best to accomodate ATC's requests &lt;strong&gt;within the safe capabilities of your airplane&lt;/strong&gt;, you'll do just fine. (In fact, I've found controllers at major airports to often be very pleasant to work with.)&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-06-23T19:50:06.927" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7454" PostTypeId="2" ParentId="7451" CreationDate="2014-06-23T19:55:01.697" Score="17" Body="&lt;p&gt;You might have heard of the elliptical lift distribution which minimizes induced drag for a given span and a given lift. Area ruling is similar, but here it is about the lengthwise distribution of cross-sectional areas of a plane, and it minimizes wave drag at Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first picture is from a Junkers patent of 1944: Junkers found out in 1943 that transsonic drag can be minimized by shifting the parts of an airplane around. In this case it was the EF-122, a research project which became the Ju-287. The easiest bodies to shift were the engine nacelles, that is why the end product has such odd engine locations. The drawing shows several shaded cross sections along lines which carry Roman numerals: Plot the sum of all areas along each line over the aircraft's length coordinate, and you get a distribution which must be optimized such that it has the maximum area for the smallest gradients.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K1a8X.png&quot; alt=&quot;Illustration from 1943 Junkers patent&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next picture shows how those plots look like. This is from a different source, so it shows generic wing-body combinations. On the left is an airplane with a fuselage shaped like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body&quot; rel=&quot;noreferrer&quot;&gt;Sears-Haak body&lt;/a&gt;. A Sears-Haak body is an optimum shape for the biggest volume with a given wave drag and was discovered by Wolfgang Haak in 1941 and again by William Sears in 1947. The wings come on top and mess up the area distribution by creating a bump in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The right plot shows what can be achieved by taking all parts of the airplane into account. The difference is shown in the small center plot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/drn62.png&quot; alt=&quot;Comparison of areas and drag over Mach of regular and area-ruled aircraft&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How this is done: Take away from the fuselage what is added by the wings. The result is a fuselage wich looks like a coke bottle. You can also add Küchenmann bodies; older airliners have plenty of them. Look especially at fuselages like those of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Blackburn_Buccaneer&quot; rel=&quot;noreferrer&quot;&gt;Blackburn Buccaneer&lt;/a&gt;, or  T-tails like those of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Il-62&quot; rel=&quot;noreferrer&quot;&gt;Illjushin Il-62&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tu-154&quot; rel=&quot;noreferrer&quot;&gt;Tupolev Tu-154&lt;/a&gt;. Today, things like engine pylons or flap track fairings are used as Küchemann bodies to smoothen out the lengthwise area distribution, and if you look carefully you will see the coke bottle technique on the fuselage around the horizontal tail of many airliners. They don't fly at Mach 1, but close enough that area ruling makes a difference already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dawing below shows the general concept and the magnitude of drag reduction achievable:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pyL8M.png&quot; alt=&quot;Gain in drag due to body waisting&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-06-14T07:08:56.940" LastActivityDate="2016-06-14T07:08:56.940" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7455" PostTypeId="2" ParentId="7452" CreationDate="2014-06-23T20:48:26.160" Score="18" Body="&lt;p&gt;I suppose it depends on what you mean by &quot;land&quot; -- For our purposes I'll define landing as putting the aircraft on the ground and decelerating to taxi speed, while meeting the other requirements of a &quot;good landing&quot; (shiny side up; rubber side down; aircraft, pilot, and passengers in reusable condition).&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;How fast can I go?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Generally you want to put the wheels on the ground at (or at least very close to) the aircraft's stall speed and then decelerate to a safe taxi speed. You can certainly force the wheels onto the ground at higher speeds, but you're still an aerial vehicle at that point and you have to bleed off the excess speed to transition to a ground (taxiing) vehicle before you can leave the runway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a general rule of thumb your final approach speed should be about 1.3 times stall speed for your selected landing configuration so you can get down to taxi speed reasonably quickly.  Putting that into some kind of context, a normal approach speed (with full flaps) in the Piper Cherokee I fly is around ~65 knots. A no-flaps approach is ~75 knots.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Looking a little deeper, you can fly the approach as fast as you want (within reason) &lt;em&gt;as long as you're comfortable doing that and confident in your ability to bleed off the extra speed with precision&lt;/em&gt;.&lt;br&gt;&#xA;  At my home field I've been chased down final by jets often enough that I know I can maintain 85+ knots until about a half-mile final, at which point I can reliably dump the extra speed, put the wheels down in the touchdown zone, and decelerate to taxi speed in time to make a &quot;normal&quot; turn-off. I also know that if it seems like I will need to carry more than about 85 knots by the half-mile point I'm better off telling ATC I'll go around and land after the faster traffic because I may not be able to safely decelerate and turn off the runway with enough room for the traffic behind me to land.&lt;br&gt;&#xA;  Keeping your speed up is really only helpful if you don't botch the landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;What's the procedure for doing this?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The procedure is basically &quot;Keep your speed up until short final&quot; -- It's something you can practice with your CFI pretty easily.&lt;br&gt;&#xA;If you elect to land without flaps the procedure is the same as the &quot;no-flap landings&quot; you should have done in training, and in most small aircraft that should be a non-event. Again, this is something you can practice with your CFI pretty easily, and it's a technique you should be familiar with in case your flap controls ever fail.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;What are the consequences?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Well, the good part is you'll be helping out ATC and the traffic behind you: if you can keep your speed up ATC will be better able to maintain separation between you and the faster aircraft behind you, instead of having to send them around or vector / re-sequence them for spacing.&lt;br&gt;&#xA;It's also fun to do this kind of thing occasionally, and helps keep your skills sharp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bad part is that any time you're not flying a &quot;normal&quot; approach you're accepting some additional level of risk. In this case you're also touching down faster, which means more energy to dissipate (hopefully through braking, but if something goes wrong you'll be dissipating that energy through impact, and as dvnrrs pointed out the energy you need to get rid of is proportional to the square of your velocity so the number goes up fast).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Remember that ultimately flying a fast final or touching down in an alternate (faster) configuration is a courtesy to ATC and the traffic you're mixing with.&lt;br&gt;&#xA;If you're comfortable doing it everyone will appreciate your help, but if you aren't comfortable with it just fly a normal approach and let ATC know you are &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/U.HTM&quot;&gt;&lt;code&gt;unable&lt;/code&gt;&lt;/a&gt; to fly faster -- the worst thing ATC will do is ask you to go around and re-sequence you with more space next time.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-23T20:48:26.160" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7456" PostTypeId="2" ParentId="7452" CreationDate="2014-06-23T23:38:45.977" Score="4" Body="&lt;p&gt;Final approach at a major hob will begin a LOT further out than at the single-strip country airport most students learn at, and mixing a 172 with the larger planes really is a significant (and expensive) issue. The cessna in the queue has everything including the glove box wide open while the 767 behind it is dancing with the Stall Demons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, approaching at full throttle and landing at full throttle are not the same. You have a lot less inertia and thus can slow down rather quickly. Once you pass the middle marker, pull the power back to idle, set the prop to full fine, and drop the flaps. You will decelerate rather quickly (and bob around a lot, practice somewhere first) and thus land at a better speed for your aircraft. If the next exit is a long way don't use any brakes, raise the flaps and just keep rolling at 60 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used to work at a busy skydiving center, when we went into the nearby international airport ATC recognized our aircraft and often cleared us for either a fast approach or a cutoff approach ( &quot;Squeeze in behind the Dash-8 that's about to land and the 737 on 5-mile. Take the first exit.&quot;) Our guys made 20-30 fast-approach landings a day and could pull this off easily. The flying club got to wait.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-06-24T12:24:56.133" LastActivityDate="2014-06-24T12:24:56.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7457" PostTypeId="1" AcceptedAnswerId="7464" CreationDate="2014-06-24T06:31:04.273" Score="39" ViewCount="15256" Body="&lt;p&gt;I've noticed that on combat aircraft the forward (nose-mounted) pitot tube is usually very long, on the order of half a meter to well over a meter on some aircraft. &lt;strong&gt;Why are they so long?&lt;/strong&gt; Surely the body of the aircraft is not disturbing the air in front of the craft, neither during subsonic nor supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example, from an AIDC F-CK-1:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Qmywd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example, from a Mirage III:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qAHkf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that I couldn't find any good pictures of the Mirage in which the entire pitot tube actually fit in the photo!&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="12720" LastEditDate="2018-02-12T02:08:25.377" LastActivityDate="2018-02-12T02:08:25.377" Title="Why are the pitot tubes on supersonic combat aircraft so long?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7458" PostTypeId="2" ParentId="7457" CreationDate="2014-06-24T06:50:24.113" Score="11" Body="&lt;p&gt;Actually, the aircraft is distorting the airflow in front of itself. As speed goes up, the shockwave builds and the aircraft starts to experience ever more sonic drag.&lt;br&gt;&#xA;The long pitots will pierce through this thick boundary layer, into the smoother airflow in front, giving correct readings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.physicscentral.com/explore/action/shockwaves.cfm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Physics Central&lt;/a&gt; has some Schlieren photos of the effect. When breaching the &quot;sound barrier&quot; the shockwave separates, which causes the sonic boom.But an area of distorted air remains.&lt;br&gt;&#xA;The image below shows the effect on a space launcher, the escape tower sticking out through the separating shockwave.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/0bB0N.jpg&quot; alt=&quot;Shockwave on a space launch vehicle&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="524" LastEditDate="2014-06-27T19:32:58.420" LastActivityDate="2014-06-27T19:32:58.420" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7459" PostTypeId="1" CreationDate="2014-06-24T15:53:23.710" Score="11" ViewCount="2768" Body="&lt;p&gt;Diamond 42 AFM says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The fuel crossfeed function can be tested simultaneously with both&#xA;  engines. Proper function can be tested by running the engines for&#xA;  approx. 30 seconds with CROSSFEED selected. The operation of both&#xA;  engines with both FUEL SELECTORS in CROSSFEED position, other than for&#xA;  this test, is prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I looked at the schematics and both fuels crossfeed pipes are completely independent and separate, including the fuel return lines and heat exchangers. Fuel flow looks almost identical (other than longer pipes) when both selectors are in CROSSFEED. So why is the manual prohibiting dual CROSSFEED ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dRnFa.png&quot; alt=&quot;DA 42 cross feed schematics&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe it's not clear from the resolution, but in the original you can see on the left image, that the cross fuel flow passes through all the filters, while the cross return line passes through the heat exchanger (the blue box on the lower right side)&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2014-06-24T16:45:16.707" LastActivityDate="2014-06-27T15:34:05.977" Title="Why is dual crossfeeding prohibited on DA42?" Tags="&lt;aircraft-design&gt;&lt;aircraft-maintenance&gt;&lt;fuel&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7460" PostTypeId="1" AcceptedAnswerId="7465" CreationDate="2014-06-24T16:01:47.940" Score="8" ViewCount="9585" Body="&lt;p&gt;Cherokee Six, 32-300 1969. Lycoming engine is fuel injected with 450 SMOH. Cold starts are easy: 1/2&quot; throttle, full rich, fuel pump on and hit starter after fuel flow starts. Runs great once running.&#xA;Hot starts are hit or miss. If it sits over an hour it may start but if I miss it it has to sit for at least another hour till I try again or forget it. I've tried 1/2&quot; throttle, full lean with and without fuel pump; full throttle, full lean with and without fuel pump and all combinations I can think of. Most of the time it spins without any cough or catch. Due for 50 hour oil change and will ask that plugs and magnetos are checked. I'm afraid to go anywhere for fear of being stranded for hours. &lt;/p&gt;&#xA;" OwnerUserId="2685" LastEditorUserId="33692" LastEditDate="2020-08-07T18:45:04.197" LastActivityDate="2020-08-07T18:45:04.197" Title="What may be the cause of hot start problems in a Lycoming fuel injected engine?" Tags="&lt;piston-engine&gt;&lt;engine-starting&gt;&lt;piper-pa-28&gt;&lt;lycoming&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7461" PostTypeId="2" ParentId="7460" CreationDate="2014-06-24T17:03:00.943" Score="1" Body="&lt;p&gt;Also have the injectors checked.  The symptoms you describe can occur when one of the injectors is not closing completely, causing flooding or an overly rich mixture.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-06-24T17:03:00.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7462" PostTypeId="1" AcceptedAnswerId="7484" CreationDate="2014-06-24T18:22:58.167" Score="16" ViewCount="1337" Body="&lt;p&gt;I'm getting a checkout at a new flight school, so I don't know anything about the maintenance records of their airplanes other than this school has been in operation for some time and so I assume everything is in order.  As PIC, though, I would think I would feel better seeing for myself that this plane I have never flown before is indeed up-to-date, at least in its required inspections.  I've never had an urge to do this before, I've always just trusted that the flight school is running things properly, but I guess since I have quite a bit more experience since my last checkout I felt like looking into this would be judicious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this overkill?  Would it be taboo or send a message of distrust to the school if I asked to see the mx logs on my plane I'm getting checked out in?  Does anyone make it a point to do this?  Thanks in advance for your comments.&lt;/p&gt;&#xA;" OwnerUserId="2686" LastEditorUserId="65" LastEditDate="2015-02-26T17:50:25.593" LastActivityDate="2018-08-13T20:59:06.573" Title="Is it an overkill to request to see airplane maintenance logs at a new flight school?" Tags="&lt;safety&gt;&lt;flight-training&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7463" PostTypeId="1" CreationDate="2014-06-24T18:48:52.740" Score="6" ViewCount="2028" Body="&lt;p&gt;Is there a website to find waypoint ID's from coordinate values? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for waypoints in the Indian ocean area. &lt;/p&gt;&#xA;" OwnerUserId="2687" LastEditorUserId="19" LastEditDate="2017-03-19T13:02:15.983" LastActivityDate="2017-03-19T13:02:15.983" Title="How to find waypoint IDs?" Tags="&lt;navigation&gt;&lt;website&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7464" PostTypeId="2" ParentId="7457" CreationDate="2014-06-24T20:38:26.213" Score="43" Body="&lt;p&gt;The length is not needed for supersonic flight, but for subsonic flight at high angles of attack. Due to the high wing sweep, a high angle of attack capability just happens to coincide with supersonic configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In subsonic flow the air ahead of the aircraft is influenced by the aircraft's pressure field, and at high angles of attack and high wing loadings this reaches out quite a bit. The pitot tube can only measure total pressure when it points into the flow direction. Ahead of the aircraft, the local flow angle increases the closer you are to the aircraft, and this increases measurement errors, because now the pitot tube sits at an oblique angle to the airflow. A longer pitot tube reaches farther out into still relatively undisturbed flow, so less compensation is needed to arrive at good values for total and static pressure. In early flight test, the pitot tube is much longer again, because the compensation factors are not yet established. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-03T14:20:19.067" LastActivityDate="2015-05-03T14:20:19.067" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7465" PostTypeId="2" ParentId="7460" CreationDate="2014-06-24T20:46:20.463" Score="8" Body="&lt;p&gt;The issue is undoubtedly vapor lock. In the fuel injected Lyc 540, the fuel injection plumbing is on the top of the engine which is the cold side of the engine when you are flying but when parked, heat rises! The following procedure runs cooler fuel through the plumbing while flooding the engine, then the flooded start procedure is necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, check your POH for the hot start procedure for your plane.  If not there, try this as it is for a very similar airplane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hot Starts on the Saratoga PA-32-300:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Intentionally flood the engine.  This runs cool fuel through the plumbing and &quot;breaks&quot; the vapor lock.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a) Full rich&lt;/li&gt;&#xA;&lt;li&gt;b) Wide open throttle&lt;/li&gt;&#xA;&lt;li&gt;c) Fuel pump on, watch fuel flow gauge&lt;/li&gt;&#xA;&lt;li&gt;d) When gauge registers flow, wait 3-5 seconds then red knob to ICO and pump off.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Crank engine with red knob still at ICO and with throttle wide open at first. Gradually close throttle (at a rate that will take you about 10 seconds to close the throttle) and it should start up at some point.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When engine catches, do several things more or less simultaneously:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a) release ignition key &lt;/li&gt;&#xA;&lt;li&gt;b) throttle to idle to avoid over-revving&lt;/li&gt;&#xA;&lt;li&gt;c) mixture full rich.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-06-25T13:18:06.733" LastActivityDate="2014-06-25T13:18:06.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7466" PostTypeId="2" ParentId="7452" CreationDate="2014-06-24T20:54:07.863" Score="4" Body="&lt;p&gt;Others have covered this subject pretty well but I will add that landing too fast will put your nosewheel down first.  The nosewheel is the weakest leg of your landing gear and if you put it down too hard you can break the nosewheel off or bend/wrinkle the firewall.  Cessna 182s are notoriously easy to damage if you slam the nose gear down.  Fixing or replacing the firewall is not an inexpensive task.&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-06-24T20:54:07.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7467" PostTypeId="2" ParentId="7463" CreationDate="2014-06-24T21:29:37.970" Score="5" Body="&lt;p&gt;One possible source is &lt;a href=&quot;http://skyvector.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skyvector&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EhYb7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use it like a paper map using the Latitude and Longitude markings to find waypoints (or other positions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g. What waypoints and routes are near S30°0.00' E112°00.00'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fXsbV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hints: Click &quot;World Hi&quot;, use your mouse's scroll-wheel to zoom, play with &quot;Layers&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are also sites with lists, by region, of waypoints with coordinates. One example is &lt;a href=&quot;http://www.fallingrain.com/world/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;fallingrain&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-24T22:36:19.913" LastActivityDate="2014-06-24T22:36:19.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7468" PostTypeId="1" CreationDate="2014-06-24T22:47:30.873" Score="3" ViewCount="1156" Body="&lt;p&gt;I've noticed a few people posting on this site who I would guess are aerospace engineers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am an A&amp;amp;P Mechanic, who is currently in the process of applying to college for an aerospace engineering degree. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does a niche exist that would involve both skill sets, and will the A&amp;amp;P license/experience give me a competitive edge for hiring in some companies?&lt;/p&gt;&#xA;" OwnerUserId="2690" LastEditorUserId="19" LastEditDate="2016-07-28T15:02:56.990" LastActivityDate="2016-07-28T15:02:56.990" Title="Is there a niche market for A&amp;P mechanics with an aerospace engineering degree?" Tags="&lt;usa&gt;&lt;aircraft-maintenance&gt;&lt;airframe-and-powerplant&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7469" PostTypeId="2" ParentId="7462" CreationDate="2014-06-25T04:18:41.230" Score="6" Body="&lt;p&gt;Is it overkill? Probably.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Schools generally do a good job maintaining their aircraft (they're used hard, but kept airworthy because if they're out of service the school is losing money). Most of what you should be concerned about is stuff you should find on a thorough preflight. You would need some specialist knowledge to determine if a log entry is a &quot;problem&quot; or not (absent something like &quot;repaired right main gear attach point and installed new right main landing gear assembly&quot; showing up).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the schools/rental outfits around here keep a status sheet with the aircraft's dispatch documents so you (and they) can easily see when required time-in-service or calendar-time inspections are coming due. If there isn't one I'd make a point of asking about inspections and such to be sure they've been done, but otherwise I'd be pretty trusting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bear in mind that there's nothing stopping an unscrupulous school or mechanic from &quot;pencil-whipping&quot; inspections. An aircraft can be perfectly airworthy on paper but full of &quot;How could they possibly have missed &lt;em&gt;that&lt;/em&gt;?!&quot; maintenance discrepancies when you preflight it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Should they let you review the logs with an instructor or mechanic if you ask? I think so.&lt;br&gt;&#xA;If you want to do this you should let them know in advance so they can have the logs available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line, as PIC you need to be sure that the aircraft is in an airworthy condition (which includes compliance with required inspections, ADs, etc.) and if you feel you need to see the logs to verify that it's your call.&lt;br&gt;&#xA;Reviewing the logs probably isn't a common request for casual rentals, but particularly if you're taking flight lessons there spending some time and reviewing the maintenance records for an aircraft is a great learning experience.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-25T04:18:41.230" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7470" PostTypeId="1" CreationDate="2014-06-25T06:37:06.580" Score="1" ViewCount="421" Body="&lt;p&gt;This is strictly not aviation related so please feel free to move it to the correct section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a 9 axis &lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_measurement_unit&quot; rel=&quot;nofollow&quot;&gt;IMU&lt;/a&gt;, which gives me yaw, pitch, roll, magnetics, gyros, accels etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I currently make use of the roll, pitch and yaw (true) however I want to learn how to use the rest of the data. I know that the raw magnetometer data can be used to judge when the true yaw is not accurate enough and even correct it. I'm reading up more on that subject at the moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However what I can't find much resources on is on how to make use of &lt;em&gt;linear acceleration&lt;/em&gt; and &lt;em&gt;angular acceleration&lt;/em&gt;. I have successfully converted the data from raw units to g/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do I obtain the acceleration of my craft with the data?&lt;/p&gt;&#xA;" OwnerUserId="2694" LastEditorUserId="247" LastEditDate="2014-06-25T07:44:11.807" LastActivityDate="2014-06-25T08:08:00.547" Title="How to make use of linear acceleration and gyroscope data?" Tags="&lt;inertial-nav-system&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-06-25T15:24:47.290" ContentLicense="CC BY-SA 3.0" />
  <row Id="7471" PostTypeId="1" AcceptedAnswerId="7475" CreationDate="2014-06-25T06:39:43.487" Score="10" ViewCount="648" Body="&lt;p&gt;Solar Impulse makes me think of a motorglider due to its aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;Upward cranked tips&lt;/strong&gt; wing configuration along with the &lt;strong&gt;engines configuration&lt;/strong&gt; particularly draw my attention:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 2 innermost engines are almost close to the thrust line&lt;/li&gt;&#xA;&lt;li&gt;The 2 outermost ones are right where the wing crank.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CpULf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Question:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Was the engines configuration mainly adopted out of structural optimization sake or do other relevant considerations (such as ease of flight control in case of asymetric engine failure etc.) come into play?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="19" LastEditDate="2016-06-22T07:49:31.580" LastActivityDate="2016-06-22T07:49:31.580" Title="What considerations drove the choice of the Solar Impulse engines configuration?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;experimental-aircraft&gt;&lt;solar-impulse&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7472" PostTypeId="2" ParentId="7470" CreationDate="2014-06-25T07:51:04.693" Score="2" Body="&lt;p&gt;You integrate accelerations to get speed and integrate speed to get position. So if you have angular speeds or even orientation, I don't see any use for angular accelerations. That does not mean the unit does not use them internally when calculating the angular speeds and/or orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The linear accelerations can be used for &lt;a href=&quot;http://en.wikipedia.org/wiki/Dead_reckoning&quot; rel=&quot;nofollow noreferrer&quot;&gt;dead reckoning&lt;/a&gt;. Airliners, and increasingly any plane with glass cockpit, have &lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;inertial navigation system&lt;/a&gt; that integrates the accelerometer and gyroscope data to keep track of position. It used to be primary means of navigation over ocean before GPS and now it is still used as backup if GPS signal is lost and for compensating errors by cross-referencing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lateral acceleration is also shown by the &lt;a href=&quot;http://en.wikipedia.org/wiki/Slip-skid_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;slip-skid indicator&lt;/a&gt; (used to be accompanied by turn rate in turn indicator, but glass cockpits often only have attitude indicator provided it is non-tumbling and maintains precision at unusual attitudes; see also &lt;a href=&quot;https://aviation.stackexchange.com/q/1645/524&quot;&gt;When/How may I replace the Turn Coordinator with an Artificial Horizon?&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-06-25T08:08:00.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7473" PostTypeId="1" AcceptedAnswerId="7474" CreationDate="2014-06-25T09:07:29.743" Score="8" ViewCount="2220" Body="&lt;p&gt;Over the years I have been aware of the term &quot;Tyro&quot; to mean a new or inexperienced pilot. I'm pretty sure it is/was used more in a military setting than a GA one, but none the less I was interested to know if anyone knows the origin of this term, and the reason why it is used? Is it still used commonly? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;em&gt;may&lt;/em&gt; be a term only used in the RAF, I don't know.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="572" LastEditDate="2015-02-19T09:13:36.027" LastActivityDate="2015-02-19T09:13:36.027" Title="What is the origin of the term &quot;Tyro&quot; for inexperienced pilots?" Tags="&lt;terminology&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7474" PostTypeId="2" ParentId="7473" CreationDate="2014-06-25T09:24:09.123" Score="13" Body="&lt;p&gt;It's just a synonym of novice, it is used outside of aviation. Like many other aviation terms (e.g. pilot) its origins precede the first manned flight and it was and is used for non-aviation novices. Aviators borrowed many existing terms.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;tyro (n.)&#xA;1610s, from Medieval Latin tyro, variant of Latin tiro (plural tirones) &#xA;&quot;young soldier, recruit, beginner,&quot; of unknown origin.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.etymonline.com/index.php?term=tyro&quot;&gt;http://www.etymonline.com/index.php?term=tyro&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-25T09:50:25.133" LastActivityDate="2014-06-25T09:50:25.133" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7475" PostTypeId="2" ParentId="7471" CreationDate="2014-06-25T10:05:59.820" Score="10" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It reduces moments in the wing spar. Major points of axial drag in this design are the wings and the fuselage. You'll see that two engines are close to the fuselage, and the other two are midway along the wing. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By placing two engines further out, they are also located where the lift is generated, reducing the necessary strength of the wing spar.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Both of the above are especially important since it's such a large wing.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There might also be some possibility of using asymmetrical thrust to ease crosswind landings with this configuration from the yaw from the outboard engines.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-06-25T22:53:06.730" LastActivityDate="2014-06-25T22:53:06.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7476" PostTypeId="1" CreationDate="2014-06-25T10:21:09.873" Score="10" ViewCount="819" Body="&lt;p&gt;Do autopilots in non-glass cockpits feed off of the gyro instruments to determine aircraft attitude, heading and rate of turn? Or do they have their own internal gyros? Since I can set the heading using the heading bug, I suppose it needs to be able to read the heading-bug offset at the very least, so there's some connection.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-06-26T20:17:01.827" Title="Do autopilots in non-glass cockpits feed off of the gyro instruments?" Tags="&lt;autopilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7477" PostTypeId="2" ParentId="7476" CreationDate="2014-06-25T10:47:09.647" Score="8" Body="&lt;p&gt;Yes, they do. Also for glass cockpit, the autopilot uses the sensors that are used for the displays (ADC, AHRS, etc).&#xA;Here are some extracts from the FLM of the SA 365N Dolphin, describing the autopilot and coupler (I selected only parts relevant to the question):&lt;img src=&quot;https://i.stack.imgur.com/09mCI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/C1u3x.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/58y0w.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="2532" LastEditDate="2014-06-25T11:50:50.087" LastActivityDate="2014-06-25T11:50:50.087" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7478" PostTypeId="1" CreationDate="2014-06-25T13:18:02.243" Score="12" ViewCount="1785" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2850/where-is-rc-aircraft-flying-allowed-in-the-us&quot;&gt;This question&lt;/a&gt; talks about flying RC models in US and latest &quot;guidelines&quot; to follow.  One of them is contacting ATC tower if you are within 5 miles of the airport&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The seems pretty simple but I'll ask anyway:&lt;br&gt;&#xA;&lt;em&gt;How would one go about contacting tower to let them know you are going to be flying RC near airport?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any specific verbiage that needs to be used?&lt;br&gt;&#xA;Can the request be denied?  (Aside from TFRs obviously.)&lt;br&gt;&#xA;Does anybody have any actual experience doing this?&lt;/p&gt;&#xA;" OwnerUserId="795" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-02-19T09:12:35.127" Title="How do you contact ATC if you want to do RC flying in the US?" Tags="&lt;air-traffic-control&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7479" PostTypeId="1" AcceptedAnswerId="7482" CreationDate="2014-06-25T13:55:35.027" Score="12" ViewCount="30973" Body="&lt;p&gt;It is often desirable to call an FAA air traffic control (ATC) facility on the telephone:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To ask a question about a &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3056/what-happens-when-i-tell-atc-to-mark-the-tape&quot;&gt;mark-the-tape&lt;/a&gt;&quot; incident&lt;/li&gt;&#xA;&lt;li&gt;To &lt;a href=&quot;https://aviation.stackexchange.com/questions/615/what-is-the-security-policy-for-getting-into-a-control-tower&quot;&gt;request a tour&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;To notify the facility of unregulated nearby operations like &lt;a href=&quot;https://aviation.stackexchange.com/questions/7478/rc-flying-in-us-contacting-atc&quot;&gt;RC plane flying&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How can one find the non-emergency telephone number for an ARTCC, TRACON, or control tower (ATCT)?&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2020-10-26T21:44:04.987" Title="How can I find telephone numbers for FAA ATC facilities?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7480" PostTypeId="1" AcceptedAnswerId="7483" CreationDate="2014-06-25T14:01:05.797" Score="26" ViewCount="8478" Body="&lt;p&gt;I (a hypothetical person) am involved in an activity like laser light shows, model rocket launches, fireworks displays, or construction which I think might be important to pilots. How can I submit this information to the FAA so that they can issue a &lt;a href=&quot;http://notams.aim.faa.gov/notamSearch/&quot;&gt;NOTAM&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2015-10-10T21:46:50.660" Title="How do I submit a NOTAM?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;notam&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7482" PostTypeId="2" ParentId="7479" CreationDate="2014-06-25T14:27:42.133" Score="7" Body="&lt;p&gt;You would think the control tower phone numbers would be listed prominently and conveniently on the FAA website.&lt;br&gt;&#xA;You would however be wrong&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your best bet would be to contact the &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot;&gt;Flight Standards District Office&lt;/a&gt; that covers your area - they can get you in touch with whatever other branches of the FAA you might need to talk to. You can also get tower phone numbers from Flight Service (1-800-WX-BRIEF).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://acukwik.com&quot;&gt;AC-U-KWIK&lt;/a&gt; also has tower phone numbers in a conveniently searchable system (punch in the airport identifier and it will be in the results you get), and the &lt;a href=&quot;http://www.aopa.org/Products-and-Services/AOPA-Airports-Directory-Print-Edition.aspx&quot;&gt;printed edition of the AOPA airport directory&lt;/a&gt; used to have tower numbers as an appendix (I'm pretty sure it still does).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sup&gt;1&lt;/sup&gt; – Actually that's not strictly correct: &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/aso/Regional_Airports/&quot;&gt;&lt;em&gt;some&lt;/em&gt; regions&lt;/a&gt; publish tower numbers prominently. Most don't, or my search skills aren't good enough to find them.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-25T14:27:42.133" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7483" PostTypeId="2" ParentId="7480" CreationDate="2014-06-25T14:56:35.507" Score="22" Body="&lt;p&gt;When I have had to file NOTAMs for skydiving demonstration jumps, I just called AFSS (1-877-4-US-NTMS) and asked to file.  The folks at Lockheed are way more helpful than the Feds used to be and will walk you through the process, but it is still good to have your information together before you call.  At a minimum you need a description of your activity, altitudes in MSL, times in zulu, and a location.  Location should be in reference to an aiport or nav aid (&quot;Within one nautical mile of the BFE airport&quot;, or &quot;27nm from the BADGER VOR on the 340 radial, for a radius of 2 nm&quot;).  If the activity requires authorization, you will also need to have that squared away before calling.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2014-06-25T14:56:35.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7484" PostTypeId="2" ParentId="7462" CreationDate="2014-06-25T15:22:12.753" Score="23" Body="&lt;p&gt;I'd refer to FAR 91.3(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot in command of an aircraft is directly responsible for and is the final authority as to the operation of that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore, I believe you have a &lt;strong&gt;duty&lt;/strong&gt; to determine that the aircraft is properly maintained.   While that doesn't mean disassembling it and checking the work yourself, I do think that its reasonable to verify that the maintenance logs have recent entries, and appear orderly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At my old flight school, I never got any grief at all (and occasional complements) when I wanted to see the logs for some reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they give you so much as an eye-roll when you ask to see the logs, that should be a cautionary sign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it is also an easy way to meet the maintenance guys, and be introduced to them as a careful, thoughtful pilot.  (The Mx guys likely despise &quot;cowboy&quot; pilots who bring back damaged equipment, and don't report it.)  You'll get to know some people at the new school, and get a reputation right off the bat.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="72" LastEditDate="2014-06-27T12:03:22.027" LastActivityDate="2014-06-27T12:03:22.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7485" PostTypeId="1" AcceptedAnswerId="7486" CreationDate="2014-06-25T15:55:07.697" Score="32" ViewCount="17928" Body="&lt;p&gt;A question I've always wondered is: can jet aircraft - not turboprop in this case - operate from 'rough' airstrips. My definition of 'rough' is grass or maybe a smooth mud airfield. I know that there's the dry lake at Edwards AFB that is used by aircraft for testing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are aircraft such as the Boeing/ Airbus passengers series - 737, 777, 747 etc - designed for or have the capability to regularly handle these airfields?&lt;/li&gt;&#xA;&lt;li&gt;Are there currently any operators using these kinds of fields?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can understand that tarmac/ concrete makes for a much smoother and more pleasant surface along with the reduce risk of FOD, hidden cracks that wheels could get caught in etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any other examples such as executive jets, fighter aircraft that regularly handle rough fields are more than welcome.&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="3386" LastEditDate="2016-11-20T10:35:42.837" LastActivityDate="2019-02-19T17:51:01.547" Title="Can jet airplanes operate on 'rough' airfields?" Tags="&lt;landing&gt;&lt;commercial-aviation&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7486" PostTypeId="2" ParentId="7485" CreationDate="2014-06-25T16:10:37.273" Score="29" Body="&lt;p&gt;The main problem with most jet airliners is that the engines are placed close to the ground. If the field is not paved, this increases the risk of damage to the engines from ingesting FOD (foreign object debris).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are, however, jets that can operate from un-paved fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737-200 has an option called a &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Gravelkit&quot; rel=&quot;nofollow noreferrer&quot;&gt;gravel kit&lt;/a&gt;.&quot; Despite having engines close to the ground, this kit helps to prevent the engine from sucking in FOD, which allows the aircraft to operate off of gravel runways. It also includes an addition to the nose gear to help prevent gravel from getting kicked up. For this reason, airlines like Canadian North still operate multiple 737-200 aircraft in order to provide service to airports with gravel runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High-wing aircraft are better suited for this type of mission (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/701/pros-and-cons-of-high-wing-vs-low-wing-design&quot;&gt;What are the pros and cons of high-wing compared to low-wing design?&lt;/a&gt;). The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-17&lt;/a&gt; is a military airlift designed to operate from remote airfields. Its wings are placed above the fuselage rather than below, which allows the engines to be mounted further above the ground. The IL-76 is a Russian aircraft of a similar configuration that also operates out of unpaved fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft with engines mounted on the rear fuselage also protect the engines from ingesting FOD. The new &lt;a href=&quot;http://www.pilatus-aircraft.com/01-api/00modules/pressarticles/1.0/files/pdf/PC-24-Fact-Sheet.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilatus PC-24&lt;/a&gt; jet advertises the ability to operate from unpaved strips. Older aircraft like the 727 or the Tu-154 have this engine placement as well, and both can operate from unpaved fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hx4my.jpg&quot; alt=&quot;737 Gravel kit&quot;&gt;&lt;br/&gt;&#xA;737-200 landing on a gravel runway. The gravel kit is visible as the small extension just below the front of the engine, and the addition to the rear of the nose gear.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-06-25T18:45:15.930" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7487" PostTypeId="2" ParentId="7485" CreationDate="2014-06-25T16:14:12.310" Score="12" Body="&lt;p&gt;I can't vouch for other airliners, but the 727 was used on dirt airfields in Africa quite often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=2BIJqb90S-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Video of 727 taking off from a dirt strip&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i118.photobucket.com/albums/o81/photon5/B727Lucapa_01.jpg&quot; alt=&quot;Photo of a 727 taking off from a dirt strip&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i118.photobucket.com/albums/o81/photon5/B727Lucapa_022.jpg&quot; alt=&quot;Photo of a 727 taking off from a dirt strip&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.147" LastActivityDate="2014-06-25T16:14:12.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7488" PostTypeId="1" AcceptedAnswerId="7489" CreationDate="2014-06-25T16:33:40.910" Score="7" ViewCount="1283" Body="&lt;p&gt;The information about the 737 &lt;a href=&quot;http://www.b737.org.uk/limitations.htm#Anti-Ice_&amp;amp;_Rain&quot;&gt;here&lt;/a&gt; mentions an interesting limitation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;737-6/900 without stiffened elevator tabs:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;After any ground deicing/anti-icing of the horizontal stabilizer using Type II or Type IV fluids, airspeed must be limited to 270 KIAS until the crew has been informed that applicable maintenance procedures have been accomplished that would allow exceedance of 270 KIAS. Once the applicable maintenance procedures have been accomplished, exceeding 270 KIAS is permissible only until the next application of Type II or Type IV deicing/anti-icing fluids.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How are certain deicing fluids, un-stiffened elevator tabs, and airspeed related here?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="572" LastEditDate="2015-02-19T09:11:10.713" LastActivityDate="2015-02-19T09:11:10.713" Title="Why are there speed restrictions applied after deicing an aircraft?" Tags="&lt;boeing-737&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7489" PostTypeId="2" ParentId="7488" CreationDate="2014-06-25T16:50:20.313" Score="10" Body="&lt;p&gt;Some deicing fluids can leave a gel-like residue on the airplane. Several incidents occurred with 737s where the residue accumulated in the elevator balance bay, causing severe oscillation/vibration in flight above 270 KIAS. These incidents resulted in the issuance of &lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/AOCADSearch/07084C655D8B45D186256BA700527D94?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;Airworthiness Directive (AD) 2002-08-20&lt;/a&gt;&lt;/strong&gt;, which required adding the 270 KIAS limitation you discovered into the 737's Airplane Flight Manual (AFM). The required &quot;maintenance procedures&quot; consist of cleaning off the deicing fluid residue. The AD also requires a one-time cleaning and sealing of the elevator balance bay.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA has received reports of numerous incidents of&#xA;  severe airframe vibration, or limit cycle oscillation (LCO), in flight after the horizontal stabilizer had&#xA;  been deiced/anti-iced on the ground. The reported incidents occurred on Boeing Model 737-600, -700, and -800 series airplanes. The empennage structure on these, as well as Model 737-700C series&#xA;  airplanes, is identical; therefore, all of these airplanes are subject to the identified unsafe condition.&#xA;  These events have been attributed to an accumulation of deicing/anti-icing fluid or other residue in&#xA;  the elevator balance panel cavities and on the external surfaces of the elevator tab.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_1_07/article_03_1.html&quot; rel=&quot;noreferrer&quot;&gt;Boeing article on the subject&lt;/a&gt; gives some more information and also has some photos showing the residue. Here's what a gummed-up 737 elevator balance panel looks like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/U2Urw.jpg&quot; alt=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_1_07/images/photo_03_1_4.jpg&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airplane deicing and anti-icing fluids can leave residue in critical areas in the wings and stabilizers. This residue can rehydrate and expand into a gel-like material that can freeze during flight and cause restrictions in the flight control systems. Therefore, attention to this residue should be part of a regularly scheduled inspection and cleaning process.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although Type III fluids have not been specifically linked to any events involving flight controls, the composition of these fluids makes them equally susceptible to residue problems as the Type II and Type IV fluids.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-06-25T20:11:11.250" LastActivityDate="2014-06-25T20:11:11.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7490" PostTypeId="2" ParentId="544" CreationDate="2014-06-25T18:29:40.433" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.xflr5.com/&quot; rel=&quot;nofollow&quot;&gt;XFLR5&lt;/a&gt; is fantastic sofware for airfoil design. It is basically a graphical user interface for xfoil @egid mentioned. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is very good for low Reynolds number flows, i.e. quite slow flying larger aircraft or model airplanes. &lt;a href=&quot;https://www.google.co.za/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB0QtwIwAA&amp;amp;url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DIFCL8IJlYnI&amp;amp;ei=hRSrU73_A8ekPZKkgcAL&amp;amp;usg=AFQjCNFd9kdU5DS-nRTlTSj8Qvlb6wg1cA&amp;amp;sig2=Pr3yq3vr5GtuyI1jps4Gdw&amp;amp;bvm=bv.69620078,d.ZWU&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; is a link to a quick tutorial on the software, and there are many other tutorials you will find on Google.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the latest versions you can even design whole planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger companies will make use of computational fluid dynamics (CFD) software, which actually solve the governing equations of fluid dynamics for a selected model (Xfoil and XFLR5 solve other very much simplified equations) Comercial CFD packages are however generally VERY expensive, although &lt;a href=&quot;http://www.openfoam.com/&quot; rel=&quot;nofollow&quot;&gt;OpenFOAM&lt;/a&gt; is an open source package that is gaining popularity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CFD is however a science of it's own and if you don't know what you are doing you are probably going to get useless results.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regards&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="2355" LastEditDate="2014-06-25T18:35:22.720" LastActivityDate="2014-06-25T18:35:22.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7491" PostTypeId="1" AcceptedAnswerId="7492" CreationDate="2014-06-25T19:19:25.267" Score="13" ViewCount="13371" Body="&lt;p&gt;In the aviation community (at least outside North America), the terms QNE, QNH, and QFE are used to describe standard pressure, local altimeter, and field elevation, respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what is the origin of the &quot;Q&quot; code names?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2016-02-05T04:15:25.077" Title="Where did the terms QNE, QNH, and QFE come from?" Tags="&lt;aviation-history&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7492" PostTypeId="2" ParentId="7491" CreationDate="2014-06-25T20:47:03.297" Score="10" Body="&lt;p&gt;QNE, QNH, and QFE are &lt;a href=&quot;http://en.wikipedia.org/wiki/Q_code&quot;&gt;Q Codes&lt;/a&gt; - the Q Codes are designed for telegraph (or radiotelegraph) use where information is transmitted in morse code and brevity is essential (e.g. &quot;QNH KJFK 2992 INS&quot; is much shorter to tap out in morse code than &quot;JFK Altimeter 29.92 inches of mercury&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are still used in verbal communication (radiotelephone), though much less frequently.&lt;br&gt;&#xA;ICAO defines a list of standard Q codes for use in aviation (&lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/communication/q_code.htm&quot;&gt;this site has a list&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding the choice of &lt;code&gt;Q&lt;/code&gt; as the prefix for these codes, this is to avoid confusion with station callsigns. &lt;a href=&quot;http://en.wikipedia.org/wiki/ITU_prefix&quot;&gt;The ITU currently will not assign prefixes beginning with &lt;code&gt;Q&lt;/code&gt;&lt;/a&gt; to any country.&lt;br&gt;&#xA;(There may be further historical reasons behind the choice of &quot;Q&quot;, but I'm not aware of any.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-06-25T20:47:03.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7493" PostTypeId="2" ParentId="7452" CreationDate="2014-06-25T20:59:36.110" Score="2" Body="&lt;p&gt;ATC is responsible for aircraft separation and they are aware of the speeds your aircraft operates at.  Land at your normal landing speed.  A large, busy airport is a bad place to try something new.&lt;/p&gt;&#xA;" OwnerUserId="2699" LastActivityDate="2014-06-25T20:59:36.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7494" PostTypeId="2" ParentId="7485" CreationDate="2014-06-25T21:29:22.197" Score="5" Body="&lt;p&gt;There are several problems: &#xA;1) Whether the landing strip can handle the weight of the aircraft and landing impact(s),&#xA;2) Whether the aircraft landing gear itself survives repeated abuse and&#xA;3) How much debris does get sucked into the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regard to fighter planes, I know for a fact that MIG-29 fighters have several slits on top of their intake (and top of their wing, resembling a shark's gills) and can actually close the main intake when landing or taking off; This way you get much less dust operating from less-than-ideally maintained runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regards to landing gear, there are special designs for that; Swedish SAAB  fighters have had longer landing gear to be able to land on the roads, refuel and rearm and fly again against the Soviets, or you could do the C-130 (I know, a turboprob, bear with me) and have multiple wheels to distribute the landing load so that the plane does not sink into the runway.&lt;/p&gt;&#xA;" OwnerUserId="2700" LastActivityDate="2014-06-25T21:29:22.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7495" PostTypeId="2" ParentId="7478" CreationDate="2014-06-25T21:36:08.577" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Any specific verbiage that needs to be used?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Just tell them you will be flying an RC aircraft with 5 miles of their airport. You should have on hand the location you have in mind. Preferably, know the distance and bearing from the airport, like &quot;3 miles to the southwest&quot;. Even better would be a more exact bearing and distance from the airport or a nearby VOR. Also know what max altitude you expect to be at. See the related question for a more thorough description (about NOTAM info, but the same general idea applies): &lt;a href=&quot;https://aviation.stackexchange.com/questions/7480/how-do-i-submit-a-notam&quot;&gt;How do I submit a NOTAM?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you are wondering how to get in touch with the tower: &lt;a href=&quot;https://aviation.stackexchange.com/questions/7479/how-to-find-telephone-numbers-for-faa-atc-facilities&quot;&gt;How can I find telephone numbers for FAA ATC facilities?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can the request be denied?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general I would say yes. One of the main rules of RC flying is to not endanger manned aircraft. If ATC thinks your selected location will break that rule, then you shouldn't fly there. That would be part of why they ask you to contact ATC in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the wording is &quot;provides the airport operator and the airport air traffic control tower...with prior notice&quot;. It says nothing about receiving approval, clearance, or permission from them. So I'm not sure if you are breaking any regulations if they say no and you fly anyway, assuming you don't break any of the other rules.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does anybody have any actual experience doing this?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not me at the moment. I will try to update if that changes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-06-25T21:36:08.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7496" PostTypeId="2" ParentId="7485" CreationDate="2014-06-25T22:20:22.210" Score="22" Body="&lt;p&gt;The mechanical strength of an airfield can be measured in CBR, meaning &lt;a href=&quot;http://en.wikipedia.org/wiki/California_bearing_ratio&quot; rel=&quot;nofollow noreferrer&quot;&gt;California Bearing Ratio&lt;/a&gt;. Another way is &lt;a href=&quot;http://www.tensors.gr/tensors/files/plates.htm#_Toc41202897&quot; rel=&quot;nofollow noreferrer&quot;&gt;Westergaard's theory&lt;/a&gt;, which uses a more analytical approach. ICAO has used both as the basis of ACN, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_classification_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft classification number&lt;/a&gt; which can be used to express the effect of a particular aircraft on the runway. The pavement in turn is classified by PCN, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pavement_classification_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;pavement classification number&lt;/a&gt;. &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/faqs/Calculating_PCN_using_the_FAA_Method.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here&lt;/a&gt; is a lengthy Boeing document on the calculation of PCN. If you know both values, you can determine how damaging the operation of a particular aircraft will be on a particular airfield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, civil aviation wants to use clean, hard surfaces. Tire pressure is a good indicator how high the tire load is, and how soft the surface may be. Commercial jets have 100 - 220 psi (7 - 15 bar) tire pressure and need a hard surface (concrete or asphalt; gravel operation is really unusual and needs lower tire pressure). Carrier-based aircraft have up to 350 psi (24 bar) tire pressure when operated from the steel deck of a carrier. On the other extreme, some military transports are still jet aircraft but need to land on unprepared surfaces, so their tire pressures go down below 100 psi (the &lt;a href=&quot;http://www.mrr.dot.state.mn.us/research/apt/DATA/CS05-01.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-17&lt;/a&gt; uses 144 psi normally, but this can be lowered to 120 psi). 125 psi (8.6 bar) is also the regular inflation pressure of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-130 E&lt;/a&gt; landing gear tires, designed for operation from unprepared surfaces. See &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a279100.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here for a study&lt;/a&gt; (PDF!) on the pressure exerted on the ground by a range of aircraft tires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the low end are the tires of gliders which routinely operate from grass strips and are fine for landing in the next field. Their inflation pressure can be as low as 50 psi (3.5 bar).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Jan mentioned, many Russian aircraft have traditionally been designed for operation from unpaved airstrips. Even fighters like the MiG-25 or the MiG-29 have (relatively) low-pressure tires (10 bar / 150 psi) which allows their operation from unprepared airstrips. The MiG-29 can even close its air intakes to prevent foreign object damage, sucking air through louvres on the upper wing. Here is a picture of the intake of a Polish MiG-29 in take-off configuration, taken from &lt;a href=&quot;http://www.airpowerworld.info/jet-fighter-planes/mig-29-fulcrum.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this website&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FAls1.jpg&quot; alt=&quot;MiG-29 intake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right air intake of a MiG-29 with main doors closed and louvres on the wing root opened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the MiG-25, you could take off from a grass strip, climb to FL800 and fly at Mach 3, and land on that grass strip again. Fascinating!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-02-19T17:51:01.547" LastActivityDate="2019-02-19T17:51:01.547" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="7497" PostTypeId="2" ParentId="7468" CreationDate="2014-06-25T23:13:48.853" Score="2" Body="&lt;p&gt;There is certainly a niche for both skill sets. Part of aerospace engineering is considering maintenance. There are multiple types of positions where having an &lt;a href=&quot;http://www.naa.edu/programs/what_is_an_ap_mechanic&quot; rel=&quot;nofollow&quot;&gt;A&amp;amp;P license&lt;/a&gt; would be a bonus.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;During the design of an aircraft, maintenance must be taken into account. Projected maintenance costs are important to the success of a design. Engineers must address this during the design of new parts.&lt;/li&gt;&#xA;&lt;li&gt;Manufacturing will have a lot of aspects in common with maintenance. Engineers must support manufacturing requirements in the design phase. Supporting emerging issues in manufacturing is also an important role.&lt;/li&gt;&#xA;&lt;li&gt;Engineering is also needed to support regular maintenance tasks. Problems come up that aren't covered in the manual, and engineers will need to advise on a solution.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Based on these subjects, the following are a few types of companies will have some positions where an A&amp;amp;P license could help:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Designers of aerospace parts&lt;/li&gt;&#xA;&lt;li&gt;Manufacturers of aerospace parts&lt;/li&gt;&#xA;&lt;li&gt;Airline maintenance departments&lt;/li&gt;&#xA;&lt;li&gt;Maintenance, Repair, and Overhaul (MRO) companies&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This focuses mostly on the commercial side of things. You can also find either civilian or military jobs supporting the military equivalent of these functions as well.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-26T15:38:48.917" LastActivityDate="2014-06-26T15:38:48.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7498" PostTypeId="1" CreationDate="2014-06-26T04:07:06.580" Score="7" ViewCount="1792" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5191/efficiency-fixed-vs-rotary-wing&quot;&gt;This question&lt;/a&gt; showed that rotary wing is less efficient than fixed wing, but the answers don't really address &lt;em&gt;why&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why are rotary wing aircraft less efficient than their fixed-wing counterparts?&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to me that the most important thing for efficiency is lift-to-drag ratio, so what makes this ratio much worse in rotary wing? Presumably it can use the same airfoil shape as fixed wing aircraft, so I could imagine a similar lift to drag ratio.&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2017-06-02T03:08:49.447" Title="Why are rotary wing aircraft less efficient than fixed wing aircraft?" Tags="&lt;aerodynamics&gt;&lt;fixed-wing&gt;&lt;rotary-wing&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7499" PostTypeId="2" ParentId="7498" CreationDate="2014-06-26T04:42:18.360" Score="12" Body="&lt;p&gt;Quick answer:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The rotary wing is moving at different speeds over the radius, and on the left and right side in forward flight, and since there can be only one optimum speed, most of the rotor is working at less than optimum speeds, lowering the lift-to-drag ratio overall.&lt;/li&gt;&#xA;&lt;li&gt;The slim rotor blade needs a reflex airfoil, an airfoil with low pitching moment, which is less efficient at creating high lift coefficients. If it would use a regular wing airfoil, it would twist horribly.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-26T21:39:46.860" LastActivityDate="2014-06-26T21:39:46.860" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7500" PostTypeId="1" AcceptedAnswerId="7502" CreationDate="2014-06-26T06:46:10.317" Score="26" ViewCount="37722" Body="&lt;p&gt;On many flight simulators, I have noticed that planes tends to get slower with increasing altitude. For example, I can reach 1100 knots just above the sea level in Google Earth flight simulator(F16), but only about 400 knots at 11km with the same plane.&lt;/p&gt;&#xA;" OwnerUserId="2702" LastEditorUserId="247" LastEditDate="2014-06-29T07:28:50.010" LastActivityDate="2021-04-27T23:12:35.693" Title="Why are planes slower at higher altitudes?" Tags="&lt;aircraft-performance&gt;&lt;airspeed&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="7501" PostTypeId="2" ParentId="7500" CreationDate="2014-06-26T08:15:27.300" Score="6" Body="&lt;p&gt;What you actually see in the cockpit is Indicated AirSpeed (IAS). The airspeed indicator actually measures dynamic pressure (which depends on speed and air density). The instrument assumes that density is 1.225 kg/cubic meter, regardless of altitude. In real life this doesn't happen. As you go higher the density decreases  and so does dynamic pressure. The instrument feels dynamic pressure decreasing and because &quot;it knows&quot; density it's constant it will show you that airspeed is decreasing.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-06-26T08:15:27.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7502" PostTypeId="2" ParentId="7500" CreationDate="2014-06-26T08:43:43.400" Score="59" Body="&lt;p&gt;This is because what you are looking at is the IAS indicator (Indicated Air Speed).&#xA;This represents the amount of relative air which flows over and under the wings of the plane. This is what creates &lt;strong&gt;lift&lt;/strong&gt; and enables the plane to fly. This is why this instrument is so important and belongs to the primary flight instruments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not to be confused with GS (Ground Speed), which can be sensed by IRS (Intertial Reference System), or by the GPS. Ground Speed is not relevant to pilot an aircraft, but it's still useful for example to determine the ETA (Estimated Time of Arrival), and for fuel estimation during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The IAS indicator indicates a lower speed because the more you climb, the less air there is.&lt;/strong&gt; So even the air flows faster, the global pressure feeling is lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, actually &lt;strong&gt;planes are not slower at higher altitudes&lt;/strong&gt;. They are faster (at least most planes whose flight envelope force them to fly faster when they are higher, otherwise they would stall, because they would have to increase their Angle of Attack too much to counterbalance the lack of air flowing above and under the wings). But when they reach their target Mach speed, their speed will decrease slowly as the outside air temperature is decreasing until end of climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for the picture being in French... But as you can see, the flight envelope of an airliner forces him to actually fly faster as it is climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qGzbV.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qGzbV.jpg&quot; alt=&quot;Airliner flight envelope&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&amp;nbsp;  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&amp;nbsp;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Different speeds&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;There are different speeds on an aircraft, and it can be quite confusing.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;IAS (Indicated Airspeed)&lt;/strong&gt; is what the instruments directly sense. It is computed by subtracting the static pressure (static ports are placed on the fuselage, vertically to relative airflow) from the total pressure (pitot tubes are placed parallel to relative airflow. This gives a &lt;strong&gt;measured dynamic pressure&lt;/strong&gt; which is then displayed in knots, km/h or mp/h. This speed is showed on most general aviation aircrafts as the main speed indication (but it's actually not a speed and more a 'pressure of air feeling').&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;CAS (Calibrated Airspeed)&lt;/strong&gt; is the same as IAS, but without instrument errors. It gives a speed related to the &lt;strong&gt;&lt;em&gt;real&lt;/em&gt; dynamic pressure&lt;/strong&gt; felt by the aircraft. This speed is showed on most airliners as the main speed indication (for pilot and autopilot).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;TAS (True Airspeed)&lt;/strong&gt; is the same as CAS when at 15°C, 0% humidity, 1013,25 hPa (29.92 inHg) (ISA, International Standard Atmosphere). This time it is literally the air speed (speed of the air): it is the &lt;strong&gt;&lt;em&gt;real&lt;/em&gt; speed at which the relative air flows around the aircraft&lt;/strong&gt;. It takes into account the fact that air density is not always the same. This speed is used when measuring or referring to an aircraft performance during cruise for example. It is also used during flight planning before the wind has been taken into account.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;GS (Ground Speed)&lt;/strong&gt; is the speed of the aircraft relative to the surface of the Earth (the equivalent of the speed showed in a car). In an airplane, we cannot use wheel speed to measure it because we are in the air, so we need GPS or IRS to do this. If there is no wind outside, TAS and GS are the same. If there is 30kt tailwind, GS is 30kt higher than TAS. This speed is used to know when you will arrive at your destination airport, and to know if you will have enough fuel (because the wind is taken into account). This speed is also used when the aircraft is on the ground (when taxiing, or more generally at low speeds when wheels are on the ground). Airlines or airports fix speed limitations when taxiing. The only way to know if you respect the limits is to look at the Ground Speed. Also, the airspeed indicator usually won't be active below a certain speed (45KIAS for the B737).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So, why is the primary airspeed indication (IAS or CAS) the wrong speed (not actual speed) of the air flowing around the aircraft?&#xA;This is because this wrong airspeed represents actually &lt;strong&gt;the real pressure feeling&lt;/strong&gt; around the wings that is &lt;strong&gt;responsible for the lift&lt;/strong&gt;. It is this parameter that we need as pilot and it is used in aircraft manuals to describe the V-speeds. It's perfect that IAS and CAS are not corrected with altitude and temperature, because if we know that our airplane stalls at 120kts for example, we won't need to care about altitude or temperature. Our airplane will stall at that same speed regardless of altitude and temperature. If we would use TAS, stall speed would be constantly changing and it would be more difficult to keep the aircraft in good and safe flying conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/matiD.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/matiD.png&quot; alt=&quot;Speeds in Aviation: Converting From Indicated Airspeed to Groundspeed&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&amp;nbsp;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is where you can find these speeds in the Boeing 737 NG cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qkZOt.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6si2P.png&quot; alt=&quot;Speeds indications in the 737NG&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2452" LastEditorUserId="2452" LastEditDate="2014-07-11T15:35:16.187" LastActivityDate="2014-07-11T15:35:16.187" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7503" PostTypeId="2" ParentId="7485" CreationDate="2014-06-26T09:14:53.213" Score="8" Body="&lt;p&gt;and then there's the &lt;a href=&quot;http://www.vfw614.de/die_vfw_614_e.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFW-614&lt;/a&gt; which was designed with overwing engines specifically for rough field operations in developing countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It sadly failed to sell, and the aircraft is now largely forgotten.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JwoNH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="1961" LastEditDate="2014-12-15T20:03:13.190" LastActivityDate="2014-12-15T20:03:13.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7504" PostTypeId="5" CreationDate="2014-06-26T10:37:19.873" Score="0" Body="&lt;p&gt;A &lt;strong&gt;rotorcraft&lt;/strong&gt;, or rotary-winged aircraft, is a heavier-than-air aircraft that uses (as the name implies) one or more spinning rotor (also known as &lt;a href=&quot;/questions/tagged/rotary-wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rotary-wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;rotary-wing&lt;/a&gt;s) to produce &lt;a href=&quot;/questions/tagged/lift&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lift&amp;#39;&quot; rel=&quot;tag&quot;&gt;lift&lt;/a&gt;.  In some types of rotorcraft, the rotor(s) also provide &lt;a href=&quot;/questions/tagged/thrust&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust&lt;/a&gt; for forward (or backward or sideways) motion, while other types require a separate source of thrust (typically an &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt;-driven &lt;a href=&quot;/questions/tagged/propeller&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;propeller&amp;#39;&quot; rel=&quot;tag&quot;&gt;propeller&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are four main types of pure rotorcraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The most-common-and-best-known-by-far is the &lt;a href=&quot;/questions/tagged/helicopter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helicopter&amp;#39;&quot; rel=&quot;tag&quot;&gt;helicopter&lt;/a&gt;, which uses one or more engines to drive its main rotor(s) directly, and obtains forward/backward/sideways thrust by tilting the rotor(s) (and helicopter) in the desired direction.  As such, helicopters can &lt;a href=&quot;/questions/tagged/hover&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;hover&amp;#39;&quot; rel=&quot;tag&quot;&gt;hover&lt;/a&gt; (unless severely overloaded), and are fully &lt;a href=&quot;/questions/tagged/vtol&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vtol&amp;#39;&quot; rel=&quot;tag&quot;&gt;vtol&lt;/a&gt;-capable.&lt;/li&gt;&#xA;&lt;li&gt;The oldest type of powered rotorcraft, the &lt;a href=&quot;/questions/tagged/autogyro&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;autogyro&amp;#39;&quot; rel=&quot;tag&quot;&gt;autogyro&lt;/a&gt; (also known as an &lt;em&gt;autogiro&lt;/em&gt;, &lt;em&gt;gyroplane&lt;/em&gt;, or &lt;em&gt;gyrocopter&lt;/em&gt;), uses an unpowered main rotor, which is tilted back slightly relative to the rest of the aircraft; the engine, instead of driving the main rotor directly, is used to provide forward thrust, and the resulting airflow through the main rotor causes it to spin (&lt;a href=&quot;/questions/tagged/auto-rotation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;auto-rotation&amp;#39;&quot; rel=&quot;tag&quot;&gt;auto-rotation&lt;/a&gt;), and, thereby, produce lift.  As a result, an autogyro requires at least some forward &lt;a href=&quot;/questions/tagged/airspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspeed&lt;/a&gt; in order to maintain altitude, and (unlike a helicopter) cannot perform a vertical &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt;, although a vertical &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt; is still doable.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;/questions/tagged/rotor-kite&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rotor-kite&amp;#39;&quot; rel=&quot;tag&quot;&gt;rotor-kite&lt;/a&gt; (or &lt;em&gt;gyrokite&lt;/em&gt; or &lt;em&gt;gyroglider&lt;/em&gt;) is essentially an autogyro &lt;em&gt;sans&lt;/em&gt; engine.  It is the rotorcraft equivalent of a &lt;a href=&quot;/questions/tagged/glider&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;glider&amp;#39;&quot; rel=&quot;tag&quot;&gt;glider&lt;/a&gt;, and, like a glider, must be towed and/or catapulted into the air, dropped from an already-airborne aircraft, or rolled down a hill in order to become airborne; once airborne, a rotor kite will slowly but continuously lose altitude unless/until it finds a good updraft.  The rotor kite is the oldest type of rotorcraft, with the earliest known flight in 1891, decades before even the first autogyro (due - again, like a glider - to not having to worry about finding a suitable engine).&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;All the other types of rotorcraft can also function (more or less well) as rotor kites in the event of an &lt;a href=&quot;/questions/tagged/engine-failure&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine-failure&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine-failure&lt;/a&gt;, allowing the pilot(s) to perform a controlled &lt;a href=&quot;/questions/tagged/forced-landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;forced-landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;forced-landing&lt;/a&gt;, rather than plummeting bricklike to their doom.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;/questions/tagged/gyrodyne&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gyrodyne&amp;#39;&quot; rel=&quot;tag&quot;&gt;gyrodyne&lt;/a&gt; is a kind of hybrid between a helicopter and an autogyro; it has a powered main rotor, like a helicopter (giving it VTOL capability, like a helicopter), but it uses separate propellers for forward thrust, like an autogyro.  When hovering, or ascending or descending vertically, the main rotor is driven entirely by the engine(s); however, as the gyrodyne accelerates forward, an increasing proportion of the force spinning the main rotor comes from the air passing through it, until, at cruise speeds, the craft is functioning essentially as an autogyro, with little or no engine power being provided to the main rotor.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some additional types of aircraft (sometimes known collectively as &lt;em&gt;powered-lift&lt;/em&gt; aircraft) function as rotorcraft during some flight regimes, but as &lt;a href=&quot;/questions/tagged/airplane&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airplane&amp;#39;&quot; rel=&quot;tag&quot;&gt;airplane&lt;/a&gt;s at other times:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;/questions/tagged/tiltrotor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tiltrotor&amp;#39;&quot; rel=&quot;tag&quot;&gt;tiltrotor&lt;/a&gt; functions as a helicopter when taking off or landing, with lift provided by a set of (almost always two) powered rotors mounted on a set of otherwise-normal &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s; however, as it transitions to forward flight, the rotors tilt forwards and more and more lift is produced by the wings rather than the rotors, until the rotors are pointed directly forwards and functioning solely as propellers (albeit &lt;em&gt;very large&lt;/em&gt; propellers), and the aircraft is flying as an airplane.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;/questions/tagged/tiltwing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tiltwing&amp;#39;&quot; rel=&quot;tag&quot;&gt;tiltwing&lt;/a&gt; is quite similar to a tiltrotor, but, as indicated by the name, tilts the entire wing rather than just the rotors; it is more efficient than a tiltrotor, as the wing is aligned with the local airflow at all times (reducing &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt;) rather than just during forward flight, but is much more mechanically complex (due to the need to &lt;em&gt;tilt the entire wing rather than just the rotors&lt;/em&gt;), and, as such, less common.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;em&gt;tailsitter&lt;/em&gt; is similar, in principle, to a tiltrotor or tiltwing; however, where a tiltrotor or tiltwing tilts the rotors or wings, respectively, a tailsitter instead tilts the &lt;em&gt;entire aircraft&lt;/em&gt;, so that, during takeoff and landing, the aircraft is (as the name indicates) sitting on what is, in horizontal flight, the &lt;a href=&quot;/questions/tagged/tail&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail&lt;/a&gt;.  Tailsitters have never been particularly successful, as entering or exiting the aircraft generally requires a ladder or crane, transitioning successfully between vertical and horizontal flight is problematic, and landing the aircraft without damaging/destroying it or its pilot is somewhat difficult when said pilot can't see the ground they're landing on.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;em&gt;stopped-rotor aircraft&lt;/em&gt; is similar to a gyrodyne; however, where a gyrodyne's main rotor continues to rotate during forward flight, that of a stopped-rotor aircraft stops turning (as you probably guessed from the name), and is locked in place to act as a conventional wing.  This is theoretically more efficient, but, in practice, it has proven extremely difficult to successfully transition from vertical, spinning-rotor flight to horizontal, stopped-rotor flight, with most designs so far having an unfortunate tendency to crash during the process.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See Wikipedia for more information on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rotorcraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pure rotorcraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Powered_lift&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hybrid (powered-lift) aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-08-10T00:13:35.137" LastActivityDate="2019-08-10T00:13:35.137" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7505" PostTypeId="4" CreationDate="2014-06-26T10:37:19.873" Score="0" Body="A rotorcraft is a heavier-than-air flying machine that uses lift generated by rotor blades revolving around one or more masts. " OwnerUserId="247" LastEditorUserId="22726" LastEditDate="2019-08-09T23:30:42.657" LastActivityDate="2019-08-09T23:30:42.657" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7506" PostTypeId="5" CreationDate="2014-06-26T10:38:57.960" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-06-26T10:38:57.960" LastActivityDate="2014-06-26T10:38:57.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7507" PostTypeId="4" CreationDate="2014-06-26T10:38:57.960" Score="0" Body="A collection of related data." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-06-26T13:13:19.413" LastActivityDate="2014-06-26T13:13:19.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7508" PostTypeId="5" CreationDate="2014-06-26T10:40:32.747" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-06-26T10:40:32.747" LastActivityDate="2014-06-26T10:40:32.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7509" PostTypeId="4" CreationDate="2014-06-26T10:40:32.747" Score="0" Body="QNH is a Q codes defined as the barometric pressure at an airport adjusted to sea level using the ICAO Standard Atmosphere. On the ground, an altimeter set to QNH reads the elevation of the airport. " OwnerUserId="247" LastEditorUserId="19" LastEditDate="2014-06-26T11:25:54.930" LastActivityDate="2014-06-26T11:25:54.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7511" PostTypeId="5" CreationDate="2014-06-26T10:46:08.100" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-06-26T10:46:08.100" LastActivityDate="2014-06-26T10:46:08.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7512" PostTypeId="4" CreationDate="2014-06-26T10:46:08.100" Score="0" Body="A taildragger is an aircraft whose undercarriage consists of (usually) two main wheels forward of the center of gravity, and a small wheel or skid to support the tail." OwnerUserId="247" LastEditorUserId="22726" LastEditDate="2020-08-18T01:00:36.857" LastActivityDate="2020-08-18T01:00:36.857" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7513" PostTypeId="2" ParentId="7471" CreationDate="2014-06-26T15:25:53.933" Score="8" Body="&lt;p&gt;The two inner engines are in the expected position. Keeping the engines as close to the fuselage as possible has two main benefits:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less adverse yaw in the case of an engine failure&lt;/li&gt;&#xA;&lt;li&gt;Less stress on the wing on the ground and during landing from the engine weight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The outboard engines are certainly unconventional. Most aircraft with four engines, expecially propeller-driven aircraft, tend to keep them all as close to the fuselage as possible. Some considerations that may have affected this decision:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less stress on the wing in flight. The weight of the engine is offset by the lift produced on the wing. Large aircraft generally use the fuel in the wing tanks last for this reason.&lt;/li&gt;&#xA;&lt;li&gt;Putting the engine at a point that is already structurally important can save some weight by combining the structure. In this case:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing angles upwards here, so there would probably be a bit more structure to support this bend&lt;/li&gt;&#xA;&lt;li&gt;The outboard landing gear is also here&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;This could also mean less weight in wiring to hook up the engines to power&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is interesting to note the design of the &lt;a href=&quot;http://www.solarimpulse.com/en/tag/solar-impulse-2&quot;&gt;Solar Impulse 2&lt;/a&gt;. There seems to be a different compromise between the two cases above, with both engines on each wing placed together roughly in the middle of the span. This seems to favor the case of saving structural weight.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-26T15:25:53.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7514" PostTypeId="5" CreationDate="2014-06-26T15:40:48.490" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-26T15:40:48.490" LastActivityDate="2014-06-26T15:40:48.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7515" PostTypeId="4" CreationDate="2014-06-26T15:40:48.490" Score="0" Body="Commonly called A&amp;P, a license granted by the FAA certifying a person is qualified to perform maintenance on an aircraft." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-06-26T15:40:48.490" LastActivityDate="2014-06-26T15:40:48.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7516" PostTypeId="2" ParentId="7476" CreationDate="2014-06-26T20:17:01.827" Score="0" Body="&lt;p&gt;Typically the Turn Coordinator and DG is used. Sometimes the Attitude indicator is used as well. Of course, if NAV tracking is used the OBS or GPS has in input as well. &lt;/p&gt;&#xA;" OwnerUserId="2712" LastActivityDate="2014-06-26T20:17:01.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7517" PostTypeId="2" ParentId="3265" CreationDate="2014-06-26T20:23:53.320" Score="2" Body="&lt;p&gt;Once you land you have to abide by the laws where you are. In the US federal laws (if there are any), when flying in US airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most US laws about airports and guns, only apply to the secured space. (Inside security), not the GA ramp or anyplace else.&lt;/p&gt;&#xA;" OwnerUserId="2712" LastActivityDate="2014-06-26T20:23:53.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7518" PostTypeId="2" ParentId="1917" CreationDate="2014-06-26T21:23:20.520" Score="27" Body="&lt;p&gt;Small aircraft need very low mounted wings to allow for a decent cabin height. The last commercial airliner which required the passengers to climb over the wing spar on their way to their seat was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_247&quot; rel=&quot;noreferrer&quot;&gt;Boeing P-247&lt;/a&gt;. Low wings do not allow the necessary space for engines, so the next best location is on the rear fuselage. Also, small aircraft have a relatively short fuselage, and the gear can be made short (and light) without risking a tail strike on rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighters need to have small moments of inertia, especially in roll, so they cannot afford to put engines on the wings. Even the Me-262 was initially planned with fuselage-mounted engines, that's why it had this peculiar triangular fuselage cross section. Only when the engines grew in diameter during development they had to be placed on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros of rear-mounted / fuselage-mounted engines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing is clean, having low drag and optimum conditions for lift creation.&lt;/li&gt;&#xA;&lt;li&gt;The engines are easy to access (if mounted at the rear fuselage. Different story with buried engines!).&lt;/li&gt;&#xA;&lt;li&gt;Smaller vertical tail needed for asymmetric thrust conditions.&lt;/li&gt;&#xA;&lt;li&gt;Shorter, lighter landing gear possible (if rotation capability is not compromised).&lt;/li&gt;&#xA;&lt;li&gt;Low roll inertia.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cons of rear-mounted / fuselage-mounted engines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No bending relief for the wing; heavier wing spar needed.&lt;/li&gt;&#xA;&lt;li&gt;No help in flutter supression (a mass ahead of the elastic line helps).&lt;/li&gt;&#xA;&lt;li&gt;Possible interference with wing wake at high angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;Forces the tail to be a T-tail configuration.&lt;/li&gt;&#xA;&lt;li&gt;More structure needed to carry the thrust forces forward.&lt;/li&gt;&#xA;&lt;li&gt;Intake noise is more audible, especially for passengers in the rear seats.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This picture of a Cessna Citation X should illustrate the point nicely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SZT3m.jpg&quot; alt=&quot;Cessna Citation X, demonstrating low wing and short gear&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T19:56:16.247" LastActivityDate="2015-05-07T19:56:16.247" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7519" PostTypeId="1" AcceptedAnswerId="7523" CreationDate="2014-06-26T22:41:16.643" Score="18" ViewCount="3699" Body="&lt;p&gt;I was browsing images of aerobatic aircraft on &lt;a href=&quot;https://www.google.com/search?q=aerobatic%20aircraft&amp;amp;tbm=isch&quot;&gt;Google&lt;/a&gt; and noticed that the vast majority of them have conventional &quot;tail-dragger&quot; landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any practical reason why this is the case, or rather an aesthetic preference?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="247" LastEditDate="2014-06-28T13:34:00.413" LastActivityDate="2020-09-16T04:52:13.713" Title="Why do most aerobatic aircraft have conventional landing gear?" Tags="&lt;landing-gear&gt;&lt;aerobatics&gt;&lt;tail-dragger&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7521" PostTypeId="2" ParentId="7519" CreationDate="2014-06-27T03:36:30.727" Score="-5" Body="&lt;p&gt;Fighter jets and related trainers outnumber (and outperform) light aerobatic aircraft, they all use tricycle gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft were tail draggers until after WWII, so it's really an issue of the aircraft design dates to a period when everything had conventional gear. There are no particular advantages to it, but an airframe cannot be converted from one to the other (the balance would be off) so if you want a classic aerobat you also get the classic landing gear.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-27T03:36:30.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7522" PostTypeId="1" CreationDate="2014-06-27T06:01:52.983" Score="4" ViewCount="1705" Body="&lt;p&gt;As far as I know:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;High blade inertia provides good pilot intervention time (the time&#xA;between recognizing engine fail and pushing the collective down).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;High kinetic energy allows for a soft touch down after flare in&#xA;autorotation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;What is the relationship between blade's inertia and rotor kinetic energy?&lt;/p&gt;&#xA;" OwnerUserId="1057" LastEditorUserId="6919" LastEditDate="2015-03-23T13:08:10.067" LastActivityDate="2015-03-23T13:08:10.067" Title="What is the relationship between blade inertia and rotor kinetic energy?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7523" PostTypeId="2" ParentId="7519" CreationDate="2014-06-27T06:02:01.353" Score="17" Body="&lt;p&gt;The tailwheel is much lighter and smaller than a nose wheel. That means reducing airplane overall weight and drag (because the landing gear is usually fixed). And it's probably cheaper, too. &lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-06-27T06:02:01.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7525" PostTypeId="2" ParentId="7522" CreationDate="2014-06-27T08:09:57.140" Score="4" Body="&lt;p&gt;The relationship between blade inertia and rotor kinetic energy is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$K = N\frac{1}{2}I\omega^2$$&#xA;$$I = \int mr^2dr$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$N$ is the number of blades&lt;/li&gt;&#xA;&lt;li&gt;$I$ is the moment of inertia of a blade&lt;/li&gt;&#xA;&lt;li&gt;$ω$ is the rotational velocity (rotor rpm)&lt;/li&gt;&#xA;&lt;li&gt;$m$ is mass&lt;/li&gt;&#xA;&lt;li&gt;$r$ is distance from hub along the blade&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For a fixed RPM increasing the moment of inertia of the blade increases kinetic energy of the rotor. An increase of the moment of inertia can be obtained by increasing the mass of the blades (inefficient, rotor gets heavy and requries more power from engine, less payload, etc.) or by placing relatively small masses at the tip of the blade.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="524" LastEditDate="2014-06-27T11:16:03.697" LastActivityDate="2014-06-27T11:16:03.697" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7526" PostTypeId="2" ParentId="7459" CreationDate="2014-06-27T12:13:09.570" Score="5" Body="&lt;p&gt;I checked both POH and Maintenance manual: neither explain why.&lt;/p&gt;&#xA;&lt;p&gt;POH:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;CAUTION&lt;/strong&gt; Do not operate with both fuel selector valves in CROSSFEED position. Do not take-off with a fuel selector valve in CROSSFEED position.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Maintenance Manual:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;B. Fuel Transfer&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;With an engine running and the fuel selector/shut-off valve set to CROSSFEED the fuel supply and return lines to the related fuel tank are shut-off. The engine fuel pump takes the fuel from the opposite engine fuel tank through the related fuel cross feed line. The fuel returned from the engine is returned to the fuel tank which supplied the fuel.&lt;/p&gt;&#xA;&lt;p&gt;The unwanted fuel flows back from the engine fuel system through a check valve and the fuel selector/shut-off valve. From the fuel selector/shut-off valve the fuel flows through the related fuel return line and a flexible hose to the fuel cooler. Fuel from the fuel cooler the fuel flows through a flexible hose back into the fuel tank that supplied the fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Interestingly, though (italics are mine):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;C. Emergency Operation&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;In an emergency (for example, an engine failure) you can set the related engine fuel selector/shutoff valve to SHUT-OFF. The fuel selector/shut-off valve has a safety gate to prevent accidental selection of the SHUT-OFF position. You must turn and hold the gate in the open position to set a fuel selector/shut-off to SHUT-OFF. When the engine fuel selector/shut-off valve is set to SHUTOFF no fuel can flow to the related engine. The engine can not run.&lt;/p&gt;&#xA;&lt;p&gt;The pilot can set the other engine fuel selector/shut-off valve to CROSSFEED and &lt;em&gt;use the fuel from both main fuel tanks to supply the engine which is operating&lt;/em&gt;. This maintain a similar fuel level in each main fuel tank.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This last paragraph, and the sentence I put in italics in particular, could indicate that if both engines are set to crossfeed they feed on both taks simultaneously, possibly (and this is speculation on my side) leading to a conflict between the two engines over the fuel and/or possible over/misuse of the feed pumps.&lt;/p&gt;&#xA;&lt;p&gt;I would like to highlight, though, that this sentence does not seem to correspond to the schematics reported (or shown in the manuals).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-06-27T12:13:09.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7527" PostTypeId="2" ParentId="7459" CreationDate="2014-06-27T15:34:05.977" Score="11" Body="&lt;p&gt;As I also could find no satisfactory explanation within the diagrams, AFM, POH or Maintenance Manual, I sent an email to the technicians at &lt;a href=&quot;http://www.diamondaircraft.com/&quot;&gt;Diamond Aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was their response, so far:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hi Chris, I can only assume that if this procedure became too routine, eventually a pilot would select the second electric boost pump on with both systems in cross feed, in flight.  The high pressure created would damage fuel lines and possibly damage the HPPs for both engines.  That would not be a good day.  You can see the step prior to going to cross feed, Fuel Pumps check Off.  I have asked Austria for an explanation but I think I am close to the mark.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Customer Support,&lt;br&gt;&#xA;  Technical Services Specialist  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Please note, that the customer service technician actually did include his contact information, but that I have removed it for privacy.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-06-27T15:34:05.977" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7528" PostTypeId="1" AcceptedAnswerId="7529" CreationDate="2014-06-27T17:42:37.467" Score="22" ViewCount="5451" Body="&lt;p&gt;Why is the use of tail-down force so prevalent in aircraft design?  Why not use canards to avoid induced drag? &lt;/p&gt;&#xA;" OwnerUserId="2726" LastEditorUserId="15311" LastEditDate="2017-12-07T16:10:40.350" LastActivityDate="2018-09-05T21:32:54.973" Title="Why is the use of tail-down force so common?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;canard&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7529" PostTypeId="2" ParentId="7528" CreationDate="2014-06-27T19:32:09.357" Score="29" Body="&lt;p&gt;If it were so simple ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To achieve natural longitudinal stability (the aircraft stays at the trimmed speed, even after disturbances like gusts), the rear lifting surfaces need to have a lower lift per area than the forward surfaces. Why? In a gust, the aircraft's angle of attack changes on all surfaces nearly at the same time. By having less lift per area, the relative lift increase due to an increase in angle of attack is higher for the rear surfaces, so now they gain relatively more lift increase than the forward surfaces. This creates an imbalance which lifts the tail up, until the old angle of attack (and, consequently, the old speed) has been reached again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A negative tail loading is a sign of high stability. This creates more drag, but allows the pilot to take the hands off the stick, to read his maps, check something or have a cup of tea. But its effect on induced drag can actually be helpful. You might be surprised, so please bear with me!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is induced drag, anyway? It is the consequence of creating lift over a limited span. The wing creates lift by deflecting air downwards. This happens gradually over the wing's chord, and creates a reaction force orthogonally to the local speed of air. This means the reaction force is pointing up- and slightly backwards. This backwards component is induced drag! The lengthwise distribution of the surfaces which do the downward deflection is of little importance (for a very technical explanation: See &lt;a href=&quot;http://www.desktop.aero/appliedaero/potential3d/InducedDrag.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, where they talk about the Treffz plane): If you have a highly loaded canard wing, its downwash will hit the wing eventually, creating a lot of backward-tilted lift there. The canard by itself will not cause so much induced drag, but will mess up the airflow over the wing. Behind the airplane it does not matter if you fly a canard or a conventional configuration, what matters is over how much span you distribute lift creation (for a constant amount of lift at a given speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You probably know that an elliptic distribution of circulation over wingspan produces the smallest induced drag. Now imagine that your wing has more a triangular than an elliptic distribution. The downward lift on the tail will reduce this hump of lift in the middle, making the distribution closer to that ideal elliptic distribution behind the whole airplane. The induced drag of the whole airplane is lowered by the tail!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another explanation: Since the wing creates a strong downwash at its center, the tail flies in an airflow which points slightly downwards. Negative lift there (being approximately orthogonal to local airflow) will actually point slightly forward, so your negatively loaded tail produces a small amount of thrust!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HnZPP.png&quot; alt=&quot;Exaggerated flow direction change between wing and tail surface&quot;&gt;&#xA;Black: Total force, Blue: Lift, Red: Drag&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you think that a triangular lift distribution is unusual, please read this &lt;a href=&quot;http://digital.library.unt.edu/ark:/67531/metadc53315/m2/1/high_res_d/19760012005.pdf&quot; rel=&quot;noreferrer&quot;&gt;NACA report by R. T. Jones&lt;/a&gt;. It takes wing weight into account, and this changes the picture how the lift distribution for minimum induced drag should look.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T19:57:12.863" LastActivityDate="2015-05-07T19:57:12.863" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7530" PostTypeId="1" AcceptedAnswerId="7531" CreationDate="2014-06-27T21:02:29.407" Score="8" ViewCount="1963" Body="&lt;p&gt;Similar to driving directions, is there a service from where we can get flying directions? Let's suppose an airplane does not have a GPS and it has to rely on &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot;&gt;VORs&lt;/a&gt; for navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know about &lt;a href=&quot;http://www.skyvector.com&quot;&gt;SkyVector&lt;/a&gt;. But if I create a flight plan there, it is a straight line. They also specify that this is not for navigation.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-06-27T21:57:05.393" Title="How to find flying directions (similar to driving directions) for navigation?" Tags="&lt;flight-planning&gt;&lt;navigation&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7531" PostTypeId="2" ParentId="7530" CreationDate="2014-06-27T21:50:38.990" Score="13" Body="&lt;p&gt;The &lt;em&gt;traditional&lt;/em&gt; (i.e., &quot;old&quot;) method is to spread out aviation charts on a large table, and use a &lt;a href=&quot;http://www.pilotmall.com/product/Jeppesen-Navigation-Plotter-PN-1-JS526500/plotters?r=googlefeed&amp;amp;gclid=COuosYSDm78CFQMNaQod_LsA6g&quot;&gt;plotter&lt;/a&gt; to hand-craft a flight plan on paper. &lt;a href=&quot;http://en.wikipedia.org/wiki/Victor_airways&quot;&gt;Victor airways&lt;/a&gt; (the VOR airway network) are depicted both on &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/vfrcharts/sectional/&quot;&gt;VFR sectionals&lt;/a&gt; and on &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/ifr/&quot;&gt;IFR low &amp;amp; high altitude enroute charts&lt;/a&gt;. The pilot/navigator will mark his or her origin and destination, and eyeball the available airways to come up with a suitable route, much like a driver would use a national atlas to find what interstates/highways to take for a long road trip. These maps depict all the information needed about distances, courses, minimum altitudes and airspace classifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planning by hand may also involve the use of the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot;&gt;Airport/Facility Directory (A/FD)&lt;/a&gt;, which has information about airports, and the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/ifrcharts/terminalprocedures/&quot;&gt;Terminal Procedures Publication&lt;/a&gt; which shows what instrument approaches are available at each airport and any necessary IFR departure procedures, takeoff weather minimums, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Nowadays,&lt;/strong&gt; people will more often use computer planning tools like &lt;a href=&quot;http://www.aopa.org/Flight-Planning.aspx&quot;&gt;AOPA Flight Planner&lt;/a&gt;, &lt;a href=&quot;http://www.fltplan.com/&quot;&gt;fltplan.com&lt;/a&gt;, etc. There are a large number of sites and software programs for this, some free, some requiring paid subscription / purchase. Most recently, &lt;a href=&quot;https://www.foreflight.com/&quot;&gt;mobile apps&lt;/a&gt; for smartphones and tablets have emerged with the same capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best such sites/software will also provide the necessary information about terrain, takeoff minimums, departure procedures and so on, and even give you current &lt;a href=&quot;http://notams.aim.faa.gov/notamSearch/&quot;&gt;NOTAMs&lt;/a&gt;, weather forecasts, etc. Many also have aircraft performance databases (or allow you to create one yourself for your airplane) and can do performance calculations for you. Some will even find the cheapest places along your route to purchase fuel, and also give you information about local transportation and accomodations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, though, that neither the FAA nor any other civil aviation authority authorizes the pilot to &lt;em&gt;rely&lt;/em&gt; on software resources. The pilot is still always responsible for verifying that he or she has complete, accurate information from official sources. In other words, if you're using software to plan your flight, and you violate restricted airspace that your flight planning software didn't warn you about, you'll be held responsible for not verifying the information and catching the error. So be careful what you use and rely on!&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-06-27T21:57:05.393" LastActivityDate="2014-06-27T21:57:05.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7532" PostTypeId="1" CreationDate="2014-06-28T17:49:47.810" Score="7" ViewCount="960" Body="&lt;p&gt;Consider two possible flight paths for a jet passenger plane; the first is a slow climb, held low over 20 or so miles to avoid other flight paths, the second a more rapid climb over 10 miles to the capacity of the plane rather than restricted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has been said to me that the more rapid climb will reduce CO&lt;sub&gt;2&lt;/sub&gt;.&#xA;But logic to me is that the rapid height gain will burn more fuel and so increase CO&lt;sub&gt;2&lt;/sub&gt; production (or perhaps are the 2 not linked I wonder).&#xA;I would appreciate being put out of my mystery on this?&lt;/p&gt;&#xA;" OwnerUserId="2733" LastEditorUserId="167" LastEditDate="2015-04-15T03:47:29.547" LastActivityDate="2015-04-15T03:47:29.547" Title="What is the most carbon-efficient way to take off in a passenger plane?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;carbon-footprint&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7533" PostTypeId="1" AcceptedAnswerId="7536" CreationDate="2014-06-28T20:30:32.137" Score="14" ViewCount="2312" Body="&lt;p&gt;Just a A4 paper sheet folded into a plane seems to fly decently. But a model of actual (big) plane made out of paper is only good at falling...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is different for paper planes? Are there &quot;modern and improved&quot; designs of paper planes?&lt;/p&gt;&#xA;" OwnerUserId="2734" LastActivityDate="2014-06-29T08:54:32.077" Title="Why simple paper planes fly better than most &quot;realistic&quot; paper plane models?" Tags="&lt;aircraft-design&gt;&lt;paper-airplane&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7534" PostTypeId="2" ParentId="7532" CreationDate="2014-06-28T22:03:21.323" Score="8" Body="&lt;p&gt;You are right, climbing adds to the fuel consumed, and increases the energy which is added to the plane, but this energy is conserved and can be reclaimed later, on descent. There are two kinds of energy to consider, potential and kinetic energy. Potential energy is weight times height, and kinetic energy is mass times speed squared, and both can be interchanged.&#xA;$$E = \frac{m}{2}\cdot v^2 + m \cdot g \cdot h$$&#xA;Nomenclature:&lt;br&gt;&#xA;    $E \:\:\:$ energy&lt;br&gt;&#xA;    $m \:\:\:$ mass&lt;br&gt;&#xA;    $v \:\:\:\:$ speed&lt;br&gt;&#xA;    $g \:\:\:\:$ gravitational constant&lt;br&gt;&#xA;    $h \:\:\:\:$ height&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust of the engines over what is needed to overcome drag, accumulated over time, builds up energy. Lift and Drag, in turn, are proportional to airspeed squared times density of air, so if the airplane climbs, it needs to fly faster to compensate for the thinner air, and drag will stay roughly constant. Thrust is also proportional to the density of the air around the aircraft, and the same goes for fuel consumption. This means that the aircraft will approximately consume the same amount of fuel over time when it flies low and slow, and when it flies high and fast. Since the task is to transport people or goods to a specific destination, flying high and fast will result in less running time at the same fuel flow. This is the reason why flying high results in less CO&lt;sub&gt;2&lt;/sub&gt; produced!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft comes close to its destination, it can now put the potential energy which has been stored as altitude to good use: In a descent, the thrust generation can be reduced by the amount of energy which is now reclaimed, just as you can ease off the gas pedal in your car when coasting downhill. So for the last half hour of the flight, the aircraft will now consume less fuel than before, and by the time it has reached its destination, the difference is just as big as the excess in consumption which was needed during climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the nitpickers: The aircraft will weigh less at the end of the trip (fuel has been consumed), so the descent will not completely compensate for the climb. On the other hand, the lower temperature at altitude will reduce fuel consumption by letting the engines run more efficiently, so in the big picture a definite gain remains.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-06-28T22:03:21.323" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7535" PostTypeId="1" AcceptedAnswerId="7539" CreationDate="2014-06-28T22:35:47.390" Score="10" ViewCount="1123" Body="&lt;p&gt;How did the Soviet Union keep airline pilots from leaving the country? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like it would have been pretty easy to do since the pilots are already in the air. And I would guess at least some flew close to the borders.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="15311" LastEditDate="2018-06-05T12:54:02.243" LastActivityDate="2018-06-05T21:25:36.120" Title="What measures were taken to keep Soviet airline pilots in the Soviet Union?" Tags="&lt;pilots&gt;&lt;airlines&gt;&lt;soviet-union&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ClosedDate="2018-06-06T08:09:02.837" ContentLicense="CC BY-SA 4.0" />
  <row Id="7536" PostTypeId="2" ParentId="7533" CreationDate="2014-06-28T22:44:03.160" Score="14" Body="&lt;p&gt;The reason is really the size! Air molecules have the same size if they flow around a small paper airplane or a big real airplane, but since their relative size is so much smaller when they flow around the real airplane, friction effects are much smaller for the big airplane. When comparing airplanes of different sizes, a dimensionless &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot;&gt;number first formulated by Osborne Reynolds&lt;/a&gt; is most helpful. It is basically the ratio of inertial to viscous forces in the airflow, and the formula is&#xA;$$Re = \frac{l \cdot v}{\nu}$$&#xA;Nomenclature:&lt;br&gt;&#xA;$Re\:\:\:$ Reynolds number&lt;br&gt;&#xA;$l\:\:\:\:\:\:$ characteristic length, for example wing chord&lt;br&gt;&#xA;$v\:\:\:\:\:$ airspeed&lt;br&gt;&#xA;$\nu\:\:\:\:\:$ kinematic viscosity of air&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flows with the same Reynolds number behave identically, but your scaled-down aircraft flies at a very different Reynolds number than the original (both speed and characteristic length are a lot lower), so the airflow around it will be very different. For it, the air looks more like a syrup when that around the original is like flowing water! Therefore, lift creation needs different means at this scale (wings with more chord, for example), and the paper airplane is better suited to cope with this particular flow condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next difference is wing loading: The paper airplane is very light; its mass per area is low. Therefore, it can fly at a slower speed than your scaled-down real airplane, and it will be easier for you to launch the paper airplane properly into the air. The scaled-down airplane needs to be thrown harder, but still straight, and this might be another reason for it falling down quickly.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-29T08:54:32.077" LastActivityDate="2014-06-29T08:54:32.077" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7537" PostTypeId="1" AcceptedAnswerId="7541" CreationDate="2014-06-29T00:16:48.630" Score="8" ViewCount="1724" Body="&lt;p&gt;At Narita Airport on the terminals there are big digital numbers visible from the runway. They aren't in some reliable order- I saw 98,91,93,95,97,99. Maybe they are Aerobridge numbers. I didn't get a photo as I only had my mobile which was off during taxiing. What are they for? &lt;/p&gt;&#xA;" OwnerUserId="2671" LastEditorUserId="572" LastEditDate="2015-02-19T09:10:20.213" LastActivityDate="2015-02-19T09:10:20.213" Title="What are these numbers visible from the runway at Narita airport?" Tags="&lt;airport&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7538" PostTypeId="2" ParentId="7537" CreationDate="2014-06-29T01:08:03.493" Score="6" Body="&lt;p&gt;Without seeing a photo of what you are referring to, I can only guess as to what the numbers were.  Most likely, they were the gate numbers.  At Narita, the gates are numbered odd on one side of the the terminal and even on the opposite.  &lt;a href=&quot;http://www.narita-airport.jp/en/guide/map/airport_map/t2/t2s_3f.html&quot; rel=&quot;noreferrer&quot;&gt;Here is a diagram of terminal two, which is what you were probably looking at.&lt;/a&gt;  At commercial airports, gates are numbered on the outside (in addition to inside the terminal) so that both ground handling staff and pilots know which gate they are at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture of a terminal at Denver International Airport. Note that the gate numbers on on both the passenger loading bridge as well as the exterior wall of the concourse:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/obqAN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-06-29T01:13:06.373" LastActivityDate="2014-06-29T01:13:06.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7539" PostTypeId="2" ParentId="7535" CreationDate="2014-06-29T02:01:20.070" Score="9" Body="&lt;p&gt;For commercial flights, the USSR had a &quot;Political Officer&quot; (KGB agent) on the plane in much the same role as Air Marshals today, just the other direction - they kept the pilots from hijacking the aircraft. The system would have also insured that the flight crew's family were safely at home in Mother Russia when the pilot was abroad. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aircraft were kept at home by the simple method of small fuel tanks. The MIG-19 was once described as a plane that &quot;goes nowhere, and does nothing, very quickly&quot;. Sure, they had decent range with external tanks, but a good number of Soviet-era fighters could realistically declare a fuel emergency right after takeoff.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-06-29T02:01:20.070" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="7540" PostTypeId="2" ParentId="7535" CreationDate="2014-06-29T07:38:00.267" Score="15" Body="&lt;p&gt;Civilian pilots had a quite comfortable life. Flying high-tech gear has an attraction in itself, and the propaganda did what it could to strengthen patriotic spirits. There were not many reasons to defect if you did not mind the nonsense in the papers but appreciated to be part of a privileged class. And everybody knew that defection would have dire consequences for all relatives left behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true for military pilots, and on top the Russian air defense was organized quite differently from NATO's, thus military pilots flew almost by remote control. This went as far as using radios which had only a dozen of pre-set frequencies. The pilots did not know the frequency, they just pushed the button with the number they were told by ground control.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-06-29T07:43:09.697" LastActivityDate="2014-06-29T07:43:09.697" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7541" PostTypeId="2" ParentId="7537" CreationDate="2014-06-29T09:41:29.973" Score="10" Body="&lt;p&gt;A good way to answer questions like this is to look at the &lt;a href=&quot;https://www.google.com/q=narita%20airport%20aerodrome%20map&quot;&gt;Aerodrome Chart&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As newmanth answered, these are gate numbers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.opennav.com/pdf/RJAA/JP-AD-2.24.1-RJAA-en-JP.pdf&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/97xxb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using Google Maps, you can also see these numbers painted on the taxiway as a guide to taxiing pilots&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xZSkP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you want to understand airport air-side signage, one document I found useful is &lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=33&amp;amp;pagetype=65&amp;amp;appid=11&amp;amp;mode=detail&amp;amp;id=136&quot;&gt;CAP 637 Visual Aids Handbook&lt;/a&gt;. It is a UK CAA document but I expect most of it applies in other parts of the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CAA refer to stand numbers, as far as I know these are the same as gate numbers. They indicate parking positions for aircraft at airport terminals, these are places that allow for the loading and unloading of passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners arriving at airports will know what gate they have to taxi to, and ATC will provide them with taxiway routes. Airports provide signs so that pilots basically know where to find their allocated gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iQ8Ij.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-06-29T18:01:53.790" LastActivityDate="2014-06-29T18:01:53.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7542" PostTypeId="1" AcceptedAnswerId="7547" CreationDate="2014-06-29T09:43:04.003" Score="9" ViewCount="1330" Body="&lt;p&gt;I stumbled upon this article: &lt;a href=&quot;http://www.gizmag.com/minix-wing-tip-vortex-aircraft-aerodynamics/15526/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Minix wing tip device promises 6% gain in fuel efficiency for airliners&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lpDqe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such an economy is appealing and I must confess the design is &quot;sexy&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone expand a little bit?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="2" LastEditDate="2014-06-29T10:10:03.023" LastActivityDate="2015-05-03T14:36:59.010" Title="Minix wingtip vortices mitigation - How does it work?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;winglets&gt;&lt;wake-turbulence&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7543" PostTypeId="5" CreationDate="2014-06-29T09:59:36.960" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-06-29T09:59:36.960" LastActivityDate="2014-06-29T09:59:36.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7544" PostTypeId="4" CreationDate="2014-06-29T09:59:36.960" Score="0" Body="Measure of the total amount of carbon dioxide (CO2) and methane (CH4) emissions of a flight as activity for the case of aviation." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-06-29T15:13:19.310" LastActivityDate="2014-06-29T15:13:19.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7545" PostTypeId="1" CreationDate="2014-06-29T12:19:48.010" Score="1" ViewCount="197" Body="&lt;p&gt;What is the maximum depth range of a FDR underwater, at which it is able to be detected by receivers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to know the maximum range of ULB pinger locator if it's submerged.&lt;/p&gt;&#xA;" OwnerUserId="2739" LastEditorUserId="556" LastEditDate="2014-06-29T13:42:21.210" LastActivityDate="2014-06-29T13:42:21.210" Title="Depth and range for FDR/CVR black box detection" Tags="&lt;commercial-aviation&gt;&lt;avionics&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2014-06-29T14:16:10.043" ContentLicense="CC BY-SA 3.0" />
  <row Id="7546" PostTypeId="2" ParentId="7545" CreationDate="2014-06-29T12:36:55.017" Score="-1" Body="&lt;p&gt;The maximum range if it's transmitting on 37.5kHz is usually between 1 and 2 kilometers in poor conditions and around 4 to 5 kilometers in normal conditions and up to 6 or 7 in good conditions. The range depends on the frequency it's transmitting but the ULB's work on 37.5kHz.&lt;/p&gt;&#xA;" OwnerUserId="2735" LastActivityDate="2014-06-29T12:36:55.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7547" PostTypeId="2" ParentId="7542" CreationDate="2014-06-29T12:58:00.477" Score="10" Body="&lt;p&gt;The tiny mass of air that this device can affect will in no way have the claimed effect on induced drag. This wingtip vortex pseudoscience is just bullshit. What can be observed as a vortex behind the wing is actually the consequence of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;vortex sheet rolling up due to downwash&lt;/a&gt; behind a lift-generating wing. But air flowing around the tip has almost nothing to do with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would compare it to those magnetic rings you are supposed to put around your fuel line to save fuel. Snake oil, in other words. There is no way this thing can reduce the wing's vortex, all it will do is to create some more local turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All it needs is a slick salesperson, a few gullible people with too much money and greed, a big promise, and the scam takes its course. This can easily yield enough investment money to allow all scammers to drive a Ferrari for a year or more. Now they have a year to come up with the next big thing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-05-03T14:36:59.010" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7548" PostTypeId="1" AcceptedAnswerId="7558" CreationDate="2014-06-30T06:12:01.040" Score="2" ViewCount="1165" Body="&lt;p&gt;As per this question.&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7537/numbers-visible-from-runway-at-narita-airport&quot;&gt;What are these numbers visible from the runway at Narita airport?&lt;/a&gt;&#xA;A UK document is linked in the accepted answer  but it doesn't list big number marking on the outside of the terminal. Surely such numbering is of little value to pilots- too coarse of location information. So who use such a gate number and how?   &lt;/p&gt;&#xA;" OwnerUserId="2671" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-02-19T09:09:40.883" Title="Why are gate numbers also marked on the outside of a terminal?" Tags="&lt;airport&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7549" PostTypeId="2" ParentId="7548" CreationDate="2014-06-30T08:29:59.677" Score="10" Body="&lt;p&gt;Of course it's helpful to the pilots, and the ground crew, too. Even if you know the airport layout in detail, it's easier to go to the gate signposted as C27, say, than to go to the seventh gate on the left. Now remember that everybody who has ever flown a plane into that airport has flown there for a first time, and everybody who's ever worked ground crew there had a first week.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just imagine the corresponding situation of a car park with somewhere between a few tens and a couple of hundred bays, where it's very important that you park in your assigned bay. Would each bay's number be written on it? Of course it would.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-06-30T08:29:59.677" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7550" PostTypeId="1" AcceptedAnswerId="7555" CreationDate="2014-06-30T11:44:13.603" Score="1" ViewCount="1681" Body="&lt;p&gt;Not sure if this is on-topic here, as the &lt;a href=&quot;https://aviation.stackexchange.com/help/on-topic&quot;&gt;official guidance&lt;/a&gt; seems a bit vague.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyways, I've got a relatively simple question.  I'm considering purchasing a Phantom 2 Vision+, but am a little unclear about what options there are in terms of controlling it.  Their website makes a big deal about being able to set waypoints (using an iPad/mobile app) and have the quadcopter operate as an autonomous drone.  And that's useful for certain things, but it seems like it would be more fun to control it directly by remote.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Judging from the video &lt;a href=&quot;https://www.youtube.com/watch?v=Ke1Qnv271sU&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, it does appear that the quadcopter ships with a remote.  But it also looks like you're expected to stick an iPhone/smartphone onto the remote?  Is that a requirement or just an optional extra?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to fly the quadcopter without using a smartphone/mobile app (using just what's included in the box)?&lt;/p&gt;&#xA;" OwnerUserId="2743" LastEditorUserId="6979" LastEditDate="2015-02-24T10:44:31.677" LastActivityDate="2015-02-24T16:45:47.913" Title="Is a smartphone required to control a DJI Phantom 2 Vision+?" Tags="&lt;flight-controls&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="1" ClosedDate="2015-02-24T09:43:21.243" ContentLicense="CC BY-SA 3.0" />
  <row Id="7552" PostTypeId="1" AcceptedAnswerId="7554" CreationDate="2014-06-30T12:13:14.200" Score="9" ViewCount="3053" Body="&lt;p&gt;I may have some false assumptions here, so correct if needed. It is said that while ATC sounds like they are &quot;in charge&quot; of the airspace surrounding a major airport, control and responsibility for any given airliner is (still) in the hands of the Pilot-In-Command (PIC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means is that if an airliner is given instructions to do something by ATC, and they are unable (or unwilling) to follow those instructions, they are able to tell ATC they are unable and ATC has to work it out, with all of the ramifications that implies. If the ATC controller wishes, they require the crew to contact ATC by other means (the dreaded phone call, I suppose) to explain, but the fact of the matter is, the passengers are ultimatley depending on the crew to keep them safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, let's take an airliner, at the gate, readying itself for a flight. They receive a pushback and are ready to taxi. They contact ATC Ground for instructions. Ground gives them taxi instructions. Who is responsible for the safety of the aircraft at that point?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do I ask this, when it should be obvious, the PIC. However, visibility out of the aircraft is limited, especially in some of the larger craft. As far as I know, there is no &quot;check the mirrors&quot; or &quot;objects in the rear view window may be larger than they appear.&quot; The PIC simply CANNOT see behind the aircraft, and so any ground vehicles, personnel, or other aircraft (small or large) could cause an accident, which would be out of the control of the PIC.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2017-01-16T13:09:15.117" LastActivityDate="2017-01-16T13:09:15.117" Title="Who is responsible for avoiding collisions on the ground; the pilot or the air traffic controller?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7553" PostTypeId="2" ParentId="1436" CreationDate="2014-06-30T12:42:24.157" Score="37" Body="&lt;p&gt;I like to train being able to determine the precise model of an aircraft.&#xA;I first try to tell if it's a Boeing or Airbus, and then I look at other details to determine the model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is to learn several differences :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;cockpit windows shape&lt;/strong&gt; (Boeing has an very specific angle) ; &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;nose shape&lt;/strong&gt; (pointy nose on Boeing, &quot;fat nose&quot; on Airbus) ;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;wingtips&lt;/strong&gt; (winglets Boeing, fence Airbus) ;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;number of engines&lt;/strong&gt; (A340, B747, A380 have 4 engines, all others have 2) ;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;gear&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since there are already nice answers describing most of these points with pictures, I will focus on the gear to add a new item to the list.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Landing Gear&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Looking at the gear adds a new hint. &lt;strong&gt;Some landing gears are unique&lt;/strong&gt;, which means that only looking at them will be enough to determine the precise aircraft type. These very specific gears are :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;B777&lt;/li&gt;&#xA;&lt;li&gt;B747&lt;/li&gt;&#xA;&lt;li&gt;A340 (2 different kinds for this aircraft only)&lt;/li&gt;&#xA;&lt;li&gt;A380&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's not worth to look at the nose wheels, because there are always 2. But the main landing gear is helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I made a &lt;strong&gt;gear cheat sheet&lt;/strong&gt; to help me learning them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1mnLU.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1mnLU.png&quot; alt=&quot;Gear cheat sheet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once these differences have been learned, the key is to use several of them to crosscheck and ease and speed up the recognition.&#xA;For example if I see the gear&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;   2&#xA;2*2 2*2&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I will then check the cockpit windows to determine whether Boeing or Airbus.&#xA;If it's Airbus, I will know it's very likely to be an A330! If it's Boeing, it will be harder since there are still 3 different aircrafts. If I want to be able to distinguish between them, I can learn new specific hints for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="2452" LastEditorUserId="11089" LastEditDate="2017-05-16T11:07:15.047" LastActivityDate="2017-05-16T11:07:15.047" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7554" PostTypeId="2" ParentId="7552" CreationDate="2014-06-30T13:30:28.527" Score="11" Body="&lt;p&gt;At all times, whether in the air or on the ground, whether at the gate or taxiing, the pilot-in-command (PIC) has final and ultimate responsibility for the safe operation of the aircraft. Per ICAO Annex 2 (with similar statements/definitions by individual civil authorities):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot-in-command of an aircraft shall, whether manipulating the controls or not, be responsible for the operation of the aircraft in accordance with the rules of the air, except that the pilot-in-command may depart from these rules in circumstances that render such departure absolutely necessary in the interests of safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you stated, the pilot is allowed to deviate from any ATC instruction or regulation to the extent necessary to ensure the safety of the crew, passengers and property. If necessary, the PIC may enlist additional resources, such as a ground crew, to deal with issues like not being able to see behind the airplane. For airline operations, this is usually spelled out by the airline's operations procedures, which the PIC effectively &quot;approves&quot; (as the ultimate authority for the aircraft's operation) and carries out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air traffic controllers have what you might call &quot;jurisdiction&quot; over certain parcels of airspace and airports. The gates and the area immediately surrounding them are usually &lt;em&gt;not&lt;/em&gt; under the jurisdiction of the control tower. They are instead managed by the airport authority. At large airports, the airport may operate a &quot;ramp control&quot; system with its own (smaller) control tower and radio frequencies. Arriving and departing aircraft coordinate with ramp control to get into and out of the gates safely. Ground crews will assist the pilot-in-command with parking and pushback operations, getting the aircraft to a point where the PIC can taxi the aircraft to leave the ramp area and enter the taxiway system in accordance with ATC taxi instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once on the taxiways, and from there to the runway and into the air, the aircraft is under the jurisdiction of the regular air traffic controllers. The controllers can divide up this area between different positions, usually a &quot;ground controller,&quot; a &quot;tower&quot; or &quot;local controller,&quot; and one or more approach/departure radar controllers.&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2014-06-30T13:30:28.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7555" PostTypeId="2" ParentId="7550" CreationDate="2014-06-30T13:44:08.023" Score="4" Body="&lt;p&gt;I'm pretty sure it works without the smart phone. If I understand correctly, the smart phone app simply relays the imagery from the camera, which can be useful for navigating especially if you do not have a clear line of sight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://arstechnica.com&quot; rel=&quot;nofollow&quot;&gt;Ars Technica&lt;/a&gt; ran &lt;a href=&quot;http://arstechnica.com/gadgets/2014/06/flying-and-crashing-a-1300-quadcopter-drone/&quot; rel=&quot;nofollow&quot;&gt;a piece&lt;/a&gt; on this very model, which might interest you.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2014-06-30T13:44:08.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7556" PostTypeId="2" ParentId="7552" CreationDate="2014-06-30T15:04:06.710" Score="5" Body="&lt;p&gt;At airports, everyone shares in the responsibility of safety. While the PIC ultimately has the responsibility of the safety of their aircraft, they cannot see and know everything from the cockpit. Each person is responsible for what they can see and what they have control of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As explained by dvnrrs, the ground controllers (or ramp controllers at large airports) give clearance for pushback. If they can't look outside and see their area of control, they can use a computer screen that shows positions of aircraft. So the controllers are responsible for avoiding aircraft and vehicles which they can see, and the ground crew is responsible for avoiding anything that they can see. As you said, the pilots have very limited visibility for pushback, which is why the pushback tractor driver is there. There are usually additional ground crew that are responsible for ensuring that the wing tips clear any obstacles as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the ground controller gives taxi instructions, again they are responsible for giving instructions that will avoid other aircraft they can see. The pilots are responsible for avoiding any obstacles they can see. In cases where the pilots don't have full visibility, such as wing tips, more care is required. ATC must ensure that the taxi instructions include only taxiways that are wide enough for the aircraft (some have width restrictions). The pilots must follow the taxiway correctly. Ground crew are responsible for parking aircraft so that they are well clear of the taxiways.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-06-30T15:04:06.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7557" PostTypeId="1" AcceptedAnswerId="7559" CreationDate="2014-06-30T21:07:55.853" Score="7" ViewCount="5420" Body="&lt;p&gt;What are the requirements for radio systems in aircraft? For example, are there requirements about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reception ability&lt;/li&gt;&#xA;&lt;li&gt;Transmit ability&lt;/li&gt;&#xA;&lt;li&gt;Transmit power&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is primarily about voice communication systems, but information about other radio systems is welcome as well.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="6919" LastEditDate="2015-04-28T02:59:20.273" LastActivityDate="2018-07-05T17:26:58.020" Title="What requirements are there for radio systems in aircraft?" Tags="&lt;faa-regulations&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7558" PostTypeId="2" ParentId="7548" CreationDate="2014-07-01T00:33:38.283" Score="6" Body="&lt;p&gt;The signs on top of the jet bridges are useful in identifying your assigned gate. Without these signs it would be easy to misidentify a neighboring gate if it also had a ground crew ready to accept an airplane. They are also useful for keeping an eye on an occupied gate from a distance while you wait for an aircraft to leave. They are also illuminated which helps locating the right gate at night or in low light. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electronic signs high on the terminal building are helpful to aircrew and ground crews. They often list aircraft info, departure/arrival airports and time to scheduled pushback. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The on ground painted lines are useful for initially lining up for a gate and in making the elaborate maneuvers required getting into certain tightly spaced gates. Once you get this close you are being guided by ground crew and have wing walkers watching your clearances. The final painted ground positions for nosewheel position (by aircraft type) are only useful to the ground staff guy with the wands -- you can't see them yourself when needed. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-07-01T00:33:38.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7559" PostTypeId="2" ParentId="7557" CreationDate="2014-07-01T01:52:42.283" Score="11" Body="&lt;h2&gt;What are the requirements for radio systems in aircraft?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Generally there aren't any, at least as far as &quot;being required to have radios&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is perfectly legal to fly around in most of the United States in a Piper Cub with no radios of any kind.&lt;br&gt;&#xA;Indeed, unless it's been retrofitted with one a Piper Cub would have no electrical system at all - so you would only be able to fly under &quot;daytime VFR conditions&quot; in airspace not requiring communication with air traffic control (absent special arrangements).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you elect to fly an aircraft equipped with radios (as most of us do) there are specific requirements those radios must meet, which are described in &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/tso/&quot;&gt;Technical Standard Orders (TSOs)&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not a comprehensive list, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For Communication radios these are outlined in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23091&quot;&gt;AC 90-50D&lt;/a&gt; and TSO C-169a.  &lt;/li&gt;&#xA;&lt;li&gt;Transponders must meet specific TSO performance criteria per &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.215&quot;&gt;FAR 91.215&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Navigation Radios (VOR/ILS/ADF) must meet specific TSO performance criteria if used under instrument flight rules.&lt;br&gt;&#xA;The TSO number for these escape me at the moment but I'm sure you can look them up.&lt;/li&gt;&#xA;&lt;li&gt;GPS systems must meet TSO C145c / TSO C146c requirements (if used for IFR navigation).&lt;/li&gt;&#xA;&lt;li&gt;The Emergency Locator Transmitter (ELT) must meet specific TSO criteria.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The requirements obviously vary based on the type of radio, and typically reference other industry standards (for example &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/90EEC549BC0253318625736800530155?OpenDocument&quot;&gt;TSO C-169a&lt;/a&gt; for VHF communication radios sends you over to RTCA/DO-186B for the actual performance criteria).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-01T01:52:42.283" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7560" PostTypeId="1" CreationDate="2014-07-01T03:21:58.040" Score="6" ViewCount="5120" Body="&lt;p&gt;On an aerobatic aircraft, such as an &lt;a href=&quot;http://en.wikipedia.org/wiki/XtremeAir_Sbach_342&quot; rel=&quot;nofollow&quot;&gt;Sbach342&lt;/a&gt;, what type of airfoil does it have and what angle of incidence does it have in relation to the fuselage?&lt;/p&gt;&#xA;" OwnerUserId="2753" LastEditorUserId="19" LastEditDate="2017-01-16T13:11:52.747" LastActivityDate="2017-01-16T13:11:52.747" Title="What are the properties of the wing (airfoil symmetry, angle of incidence) of an aerobatic aircraft?" Tags="&lt;aircraft-design&gt;&lt;fixed-wing&gt;&lt;aerobatics&gt;&lt;tail-dragger&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7561" PostTypeId="1" CreationDate="2014-07-01T08:27:40.720" Score="8" ViewCount="498" Body="&lt;p&gt;Most people in the aviation world know that it's legal to fly a Super Cub without a radio in the US. Is it legal in other parts of the world, specifically Germany?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I stumbled across this section in a copy of the German AIP VFR:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;GEN 1-12 Radio and Air Navigation Equipment of Aircraft (NfL II-11/05)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;Radio and air navigation equipment for VFR flights&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(1) For VFR flights, aeroplanes, rotorcraft, powered gliders, gliders,&#xA;  aerodynamically controlled ultralight aircraft, gyrocopters, airships,&#xA;  and free balloons shall be equipped with one VHF transceiver covering&#xA;  at least those frequencies in the range 118.000 to 136.975 MHz that&#xA;  are required for the planned flight; the transmitter output power and&#xA;  receiver sensitivity shall be at least such as to ensure clear&#xA;  radio-telephony communication with the ATC and AIS units, taking into&#xA;  account the operational characteristics of the aircraft and the route&#xA;  flown.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Para 1 does not apply to flights at aerodromes without an ATC unit&#xA;  which are conducted during the day and which do not leave the vicinity&#xA;  of the departure aerodrome (Art. 3a para 3 of the German Aviation&#xA;  Regulation [LuftVO]). Local regulations of the responsible authority&#xA;  of a Land (Art. 21a para 1 of the German Aviation Regulation [LuftVO])&#xA;  shall remain unaffected.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does this mean cross country flight without a radio is illegal in Germany? Or is the part &quot;shall be equipped with one VHF transceiver covering at least those frequencies ... that required for the planned flight&quot; a loophole meaning you can go as long as you don't cross into any areas where radio is required? (thus effectively rendering 3.(3) above superfluous)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that as long as you remain in class E and G airspace, I don't actually have to talk to anyone; would I still be legally required to carry a radio?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ignore the other airspace classes for now, as C has mandatory radio communication and F has its own can-of-worms rules in Germany, and neither A or B are used at all (class F is about to be discontinued and replaced with class G and a Radio Mandatory Zone in accordance with EU regulation 923/2012 &quot;SERA&quot;)&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="62" LastEditDate="2019-02-24T00:59:00.920" LastActivityDate="2019-06-11T13:42:44.397" Title="Is it legal to fly without a radio in Germany?" Tags="&lt;radio-communications&gt;&lt;regulations&gt;&lt;germany&gt;&lt;luftvo&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="7562" PostTypeId="2" ParentId="7561" CreationDate="2014-07-01T09:11:00.807" Score="2" Body="&lt;p&gt;paragraph 3 clearly states that the only exception to the requirement to carry a radio set is when you're not leaving the immediate vicinity of the airfield, and then only when there's no ATC coverage.&lt;br/&gt;&#xA;That effectively means you can fly a few circuits at low altitude over a small field, but even then many of those would be close enough to a larger airport that has ATC coverage that they'd be covered by that airport's ATC system rather than having their own.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;The only &quot;loophole&quot; would be if you could convince authorities that your flight wasn't planned, good luck with that.&lt;br/&gt;&#xA;Effectively that'd most likely mean you're having to prove to them that you went to the airfield without wanting to fly, just jumped into an aircraft, took off, and started zooming around the sky. Something that's so far out there nobody's going to buy it.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-07-01T09:11:00.807" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7563" PostTypeId="5" CreationDate="2014-07-01T11:39:32.027" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-01T11:39:32.027" LastActivityDate="2014-07-01T11:39:32.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7564" PostTypeId="4" CreationDate="2014-07-01T11:39:32.027" Score="0" Body="The German Aviation Regulations or &quot;Luftverkehrs-Ordnung&quot;, commonly referred to as &quot;LuftVO&quot;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-07-01T13:06:32.127" LastActivityDate="2014-07-01T13:06:32.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7565" PostTypeId="5" CreationDate="2014-07-01T11:52:31.480" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-01T11:52:31.480" LastActivityDate="2014-07-01T11:52:31.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7566" PostTypeId="4" CreationDate="2014-07-01T11:52:31.480" Score="0" Body="The Soviet Union (officially the Union of Soviet Socialist Republics, or USSR) was a nation that existed from 1922 to 1991." OwnerUserId="247" LastEditorUserId="6919" LastEditDate="2015-05-19T12:42:29.283" LastActivityDate="2015-05-19T12:42:29.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7567" PostTypeId="2" ParentId="7560" CreationDate="2014-07-01T15:06:04.043" Score="2" Body="&lt;p&gt;Most of these aircraft, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Extra_EA-300&quot; rel=&quot;nofollow&quot;&gt;Extra 300&lt;/a&gt;, will have symmetrical airfoils at 0 angle of incidence. As DeltaLima pointed out, the angle of incidence is the angle of the chord line of the airfoil versus the longitudinal axis of the aircraft. Angle of attack is the angle of the airflow versus the chord line of the airfoil, which of course changes with flight conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A symmetrical airfoil allows the wing to perform just as well upside down as right side up. An angle of incidence of 0 degrees helps the plane as a whole to perform in a similar way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will probably not find many specifics about the airfoil design, as these are specialized aircraft and airfoil design is generally a proprietary subject. However, you can look at symmetric airfoils in places like the &lt;a href=&quot;http://aerospace.illinois.edu/m-selig/ads/coord_database.html&quot; rel=&quot;nofollow&quot;&gt;UIUC Airfoil Database&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-07-01T15:06:04.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7568" PostTypeId="1" AcceptedAnswerId="7569" CreationDate="2014-07-01T15:14:21.990" Score="9" ViewCount="3150" Body="&lt;p&gt;Commercial aircraft are identified on the radio with an airline call sign and their flight number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer on this &lt;a href=&quot;https://aviation.stackexchange.com/questions/6280/why-are-some-atc-callsigns-different-than-the-flight-number&quot;&gt;related question&lt;/a&gt; mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the telephony designator of the aircraft operating agency&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How is this designator assigned? Are there requirements for getting one?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-13T18:01:15.190" Title="How is an airline call sign assigned?" Tags="&lt;air-traffic-control&gt;&lt;call-sign&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7569" PostTypeId="2" ParentId="7568" CreationDate="2014-07-01T16:24:09.870" Score="9" Body="&lt;p&gt;These designators are assigned, on request, by ICAO. The request is made by the applicant through their National Aviation Autority. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are actually two designators: the ICAO three letter code and the ICAO R/T designator.&#xA;All assigned designators are published in &lt;a href=&quot;http://www.emfa.pt/infoaero/conteudos/galeria/ICAO/Docs_Pagos/8585.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO document 8585&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two things are to be considered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The three letter code must be unique to the aircraft operator &lt;/li&gt;&#xA;&lt;li&gt;The R/T designator (callsign) must not cause confusion with other operators flying in the same area,  preferably at most three syllables long and it must be pronounceable in at least one of the following languages; English, French, Spanish or Russian. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since there are many operators that have &quot;airline&quot; or &quot;airways&quot; in their name, that word is usually avoided in the R/T designator as it easily causes confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For pilots it is not too difficult, they are typically paying attention specifically to their own R/T callsign. For controllers it is more difficult since they have to associate the three letter code on their screen with R/T designators that or not related in an obvious way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;British Airways has three letter code BAW and R/T designator&#xA;&quot;SPEEDBIRD&quot;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thomas Cook Airlines Ltd has three letter code TCX, and R/T&#xA;designator &quot;KESTREL&quot;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thomas Cook Airlines Belgium has three letter code TCW, and R/T&#xA;designator &quot;THOMAS COOK&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thomson Airways has three letter code TOM, and R/T designator &quot;TOMSON&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since the application goes through the NAA, there are slight differences in the procedure from country to country. Some examples are listed below:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Netherlands&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ais-netherlands.nl/aim/2013-11-28-AIRAC/eAIP/html/eAIC/EH-eAIC-04-05-B_nl-en-GB.html&quot; rel=&quot;nofollow&quot;&gt;AIC&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;USA &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%20120-26K.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Advisory Circular AC 120-26K&lt;/a&gt; and &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/CNT/1-4.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Order JO 7340.2D&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.nbaa.org/ops/airspace/issues/call-signs/&quot; rel=&quot;nofollow&quot;&gt;NBAA call-sign application guidance website&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-13T18:01:15.190" LastActivityDate="2015-10-13T18:01:15.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7571" PostTypeId="5" CreationDate="2014-07-01T17:25:31.330" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-01T17:25:31.330" LastActivityDate="2014-07-01T17:25:31.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7572" PostTypeId="4" CreationDate="2014-07-01T17:25:31.330" Score="0" Body="Electric engine used as non conventional propulsion system of an aircraft." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-07-01T18:33:27.443" LastActivityDate="2014-07-01T18:33:27.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7573" PostTypeId="5" CreationDate="2014-07-01T18:07:00.470" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-01T18:07:00.470" LastActivityDate="2014-07-01T18:07:00.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7574" PostTypeId="4" CreationDate="2014-07-01T18:07:00.470" Score="0" Body="Papi is the short for &quot;Precision approach path indicator&quot;. It's a visual aid providing guidance information to help a pilot acquire and maintain the correct approach." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-07-01T18:39:16.250" LastActivityDate="2014-07-01T18:39:16.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7575" PostTypeId="1" AcceptedAnswerId="7577" CreationDate="2014-07-01T20:14:17.033" Score="10" ViewCount="1516" Body="&lt;p&gt;In the Denver metropolitan area (where I fly), we have a large class B area around KDEN, with the associated approach control providing services to the surrounding airports (KAPA, KBJC, KFTG) as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whenever I fly IFR and am in contact with Denver Approach, I am given the Denver altimeter instead of the altimeter of the closet airport which is usually (slightly) different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I use the Denver setting while in contact with Denver Approach, since I've always assumed everyone else in contact with them are doing the same, and only switched to the destination altimeter after being handed off to the tower controller at my destination.  Is this considered the correct procedure?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2017-11-12T20:43:11.507" LastActivityDate="2017-11-12T20:43:11.507" Title="Which altimeter setting should I use?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7576" PostTypeId="2" ParentId="7560" CreationDate="2014-07-01T20:18:13.360" Score="12" Body="&lt;p&gt;There are a few things to consider for a good aerobatic airfoil. The transition between attached and separated airflow has a big influence for spins or snap rolls, and a good aerobatic airfoil needs only a small change in AoA (angle of attack) to fully transition between the two. To achieve this, it helps to shape the forward part similar to an ellipse (a lemniscatic function, to be precise), and to use a nearly straight line for the last 70% of chord. The goal is to have a &lt;a href=&quot;http://www.cfd-online.com/Wiki/Stratford%27s_separation_criterion&quot; rel=&quot;noreferrer&quot;&gt;Stratford pressure rise&lt;/a&gt; on those 70% which gives the maximum possible pressure gradient without separation. Increase AoA just a little, and you have fully separated flow over those 70%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When all works as planned, you can get the plane out of a spin by applying rudder at, say, 45° before the fuselage points in the desired direction and get out of the spin within 10° of that direction. Same goes for snap rolls, they get really snappy. It is a real pleasure to fly such planes, but you need some discipline. There are no aerodynamic warnings before you stall, and stalling comes immediately. On the other side, with the limited lift loss of such an airfoil and the powerful engines of aerobatic airplanes, stalling is no big issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A major reason for mounting the wing at 0° incidence is that you need little elevator correction in a roll. Rolling happens about the longitudinal axis of inertia, and if the wing is aligned with this axis, it has 0° AoA at 90° and 270° of the roll and at 180° the inverse of the AoA it had in level flight. With a symmetrical airfoil, lift is always correct, and if the aircraft flies at zero stability, you need not to move the elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mistimed elevator movement in rolls leads to immediate changes in flight path direction (happens really easily, and is easy to observe from the ground), and it is very hard to pitch the whole airplane just at the right time so it has no lift (read: side force) in knife edge flight, but the right lift in inverted flight. Just for flying inverted, many regular airfoils are just fine, but it is in the transitions where the symmetric airfoil has a clear advantage. A fast roll with a cambered airfoil will result in a corkscrew-shaped flight path because you cannot pitch quickly, let alone precisely, enough.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-07-05T09:09:28.547" LastActivityDate="2014-07-05T09:09:28.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7577" PostTypeId="2" ParentId="7575" CreationDate="2014-07-01T20:47:43.183" Score="8" Body="&lt;p&gt;Yes, that is correct procedure, except that if you're flying an instrument approach, switching to destination altimeter should be part of your approach setup &quot;chart briefing&quot; (which likely happens before you get handed off to the tower).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0702.html&quot;&gt;AIM 7-2-2(a)(1)&lt;/a&gt; (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Set the altimeter] to the current reported altimeter setting of a station along the route and within 100 NM of the aircraft, or if there is no station within this area, the current reported altimeter setting of an appropriate available station. When an aircraft is en route on an instrument flight plan, &lt;strong&gt;air traffic controllers will furnish this information to the pilot at least once while the aircraft is in the controllers area of jurisdiction&lt;/strong&gt;. In the case of an aircraft not equipped with a radio, set to the elevation of the departure airport or use an appropriate altimeter setting available prior to departure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unfortunately the AIM text doesn't directly address destination altimeter settings, but &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0401.html&quot;&gt;section 4-1-8&lt;/a&gt; alludes to the fact that controllers must verify you have the best destination altimeter setting, either by telling you or by having you report that you have the current ATIS or the AWOS/ASOS broadcast (&quot;the numbers&quot; for the latter):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Numerous approach control facilities have established programs for arriving VFR aircraft to contact approach control for landing information. This information includes: wind, runway, and altimeter setting at the airport of intended landing. This information may be omitted if contained in the Automatic Terminal Information Service (ATIS) broadcast and the pilot states the appropriate ATIS code.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; Such information will be furnished upon initial contact with concerned approach control facility. The pilot will be requested to change to the tower frequency at a predetermined time or point, to receive further landing information.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For instrument approaches under IFR, setting and checking the altimeter to the destination's setting should be part of your approach briefing checklist. My personal &quot;checklist&quot; includes the altimeter setting as part of the weather information when I get to the bottom of the chart and check ATIS/ASOS/AWOS numbers against the approach minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestly enough, the FAA's &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot;&gt;Instrument Flying Handbook&lt;/a&gt; doesn't have much to say on altimeter settings at all (except for mentioning that keeping the setting up to date is important and that bad things can happen if you don't).&lt;/p&gt;&#xA;" OwnerUserId="909" LastEditorUserId="909" LastEditDate="2014-07-01T20:55:33.637" LastActivityDate="2014-07-01T20:55:33.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7578" PostTypeId="1" AcceptedAnswerId="7602" CreationDate="2014-07-01T21:33:40.847" Score="12" ViewCount="4572" Body="&lt;p&gt;All glass cockpits seem to have the same basic setup for the primary instruments. Altitude tape on the right, air speed tape on the left, turn coordinator on top and an artificial horizon in the background. I can't find any good information on how the glass cockpit came to be and more specifically, how this layout was developed and adopted. I'm curious about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Who developed the first glass cockpits?&lt;/li&gt;&#xA;&lt;li&gt;Which planes first used these glass cockpits?&lt;/li&gt;&#xA;&lt;li&gt;How was the current layout developed, were other layouts in use beforehand?&lt;/li&gt;&#xA;&lt;li&gt;Was there any resistance or difficulty in getting these systems adopted amongst pilots or their companies?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="81" LastEditorUserId="247" LastEditDate="2014-07-02T12:58:29.433" LastActivityDate="2015-05-04T18:09:08.350" Title="What is the history of glass cockpits?" Tags="&lt;avionics&gt;&lt;aviation-history&gt;&lt;glass-cockpit&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7579" PostTypeId="2" ParentId="7578" CreationDate="2014-07-01T21:57:10.060" Score="4" Body="&lt;p&gt;Electronic displays had been used extensively in military aircraft since the 1960s, but I believe NASA Langley with their Terminal Configured Vehicle program was most directly responsible for the initial research of electronic flight displays in commercial aircraft. Starting in 1973, they used a modified Boeing 737 to begin research into using computer displays on commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting on page 36, this &lt;a href=&quot;http://history.nasa.gov/SP-4216.pdf&quot; rel=&quot;nofollow&quot;&gt;history of the 737 flying lab&lt;/a&gt;, goes into great detail of their research on electronic flight decks.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2014-07-01T21:57:10.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7580" PostTypeId="2" ParentId="7578" CreationDate="2014-07-01T22:10:31.483" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I can't find any good information on ... how this layout was developed&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The glass cockpit arrangement for the primary flight display copies the defacto standard analog instrument minimal T arrangement that pilots are/were used to.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Airspeed     Attitude   Altimeter        Airspeed       Attitude     Altimeter&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yZmsS.jpg&quot; alt=&quot;enter image description here&quot;&gt; .........   &lt;img src=&quot;https://i.stack.imgur.com/QDx2Y.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;              Heading                                  Heading&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_instruments#T_arrangement&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-01T22:16:02.757" LastActivityDate="2014-07-01T22:16:02.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7582" PostTypeId="1" CreationDate="2014-07-02T05:39:03.667" Score="7" ViewCount="5061" Body="&lt;p&gt;I read on a site that a 747 taking off emits the same amount of air pollution in the first 5 miles or so as 3000 cars. This seems extreme (accepting that the cars will be average). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any more precise comparisons for 2 or 4 engine aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2733" LastEditorUserId="6919" LastEditDate="2015-04-28T03:00:42.763" LastActivityDate="2019-02-09T21:59:02.993" Title="How much pollution is created by an airplane taking off?" Tags="&lt;takeoff&gt;&lt;carbon-footprint&gt;&lt;emissions&gt;" AnswerCount="3" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7583" PostTypeId="2" ParentId="7522" CreationDate="2014-07-02T12:13:38.037" Score="3" Body="&lt;p&gt;A simple &quot;no math&quot; answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher the inertia, the more it can &quot;resist&quot; anything that wants to change its velocity.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. High blade inertia is good pilot intervention time ( the time between engine fail and collective down which army requirement is 2 second.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It usually takes the pilot a few seconds to realize things are going wrong.  Call it the &quot;WTF!&quot; moment.  A high inertial rotor system will see less decay in speed during those moments.  A successful auto-rotation requires preserving that rotor RPM.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. High kinetic energy is good for soft tough down after flare in autorotation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you made it past the &quot;WTF&quot;, kept the rotor speed up, picked out your landing spot, and are in full auto-rotation.  As you approach the ground you now are going to need to &quot;flare&quot; - increase collective and haul back on the cyclic.  The higher inertia rotor system allows for a &quot;sloppier&quot; flare because the inputs (to use the rotors stored energy to arrest the descent) will have less effect on the RPM.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. What is the relationship between them?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In both cases, the higher inertia system works in the pilots favor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An extreme example of a high inertia rotor is the (never ending) &lt;a href=&quot;https://www.youtube.com/watch?v=Q3qPV3Fpk5Q&quot; rel=&quot;nofollow&quot;&gt;Carter-Copter Gyro project&lt;/a&gt;.  They have &quot;weighted&quot; tips to increase rotor inertia.&#xA;Older video, but jump takeoff demo'd around 40 sec mark.  The rotor on an auto-gyro can be &quot;pre-rotated&quot; with some assist from the engine, but when he makes that jump, that is all inertia working in his favor.&lt;/p&gt;&#xA;" OwnerUserId="2757" LastEditorUserId="6919" LastEditDate="2015-03-23T13:07:37.387" LastActivityDate="2015-03-23T13:07:37.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7584" PostTypeId="2" ParentId="7550" CreationDate="2014-07-02T12:31:40.687" Score="1" Body="&lt;p&gt;The phone/ipad is used to relay video only and other wise control the camera. You also get some flight information such as distance, elevation, speed relayed to your display. It is not a requirement to use it but if you are never going to use it, why not get a straight Phantom 2, which doesn't have a camera on it. It's much cheaper. The camera system on the Phantom 2 vision+ is very impressive though!&lt;/p&gt;&#xA;" OwnerUserId="2758" LastActivityDate="2014-07-02T12:31:40.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7585" PostTypeId="1" CreationDate="2014-07-02T13:18:21.437" Score="17" ViewCount="3209" Body="&lt;p&gt;I saw &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/0/00/Sukhoi_Su-33_on_Admiral_Kuznetsov-2.jpg&quot; rel=&quot;noreferrer&quot;&gt;this picture&lt;/a&gt; in Wikipedia with a Su-33 jet on carrier deck with some barrier raised from the deck behind the jet tail:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KFACg.jpg&quot; alt=&quot;some barrier behind the jet tail&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this barrier for and what's the official term for it?&lt;/p&gt;&#xA;" OwnerUserId="2759" LastActivityDate="2017-10-20T15:14:12.687" Title="What's the name and purpose of a barrier raised behind a carrier based jet?" Tags="&lt;jet&gt;&lt;aircraft-carrier&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7586" PostTypeId="2" ParentId="7585" CreationDate="2014-07-02T13:27:47.013" Score="8" Body="&lt;p&gt;It's a &lt;a href=&quot;http://en.wikipedia.org/wiki/Blast_fence&quot;&gt;blast fence&lt;/a&gt; to prevent that the groundcrew walking behind the jet get blown away by the jet blast.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-07-02T13:27:47.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7587" PostTypeId="2" ParentId="7585" CreationDate="2014-07-02T13:28:15.600" Score="5" Body="&lt;p&gt;It is a blast fence to protect the planes behind it from the destructive force of the jet blast of the plane in front of the fence.  The plane in position for takoff will go to full power for takeoff.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check out this video of a pickup truck being towed through the full power exhaust behind a jet.  &lt;a href=&quot;https://www.youtube.com/watch?v=DFP4xl0V0mk&quot; rel=&quot;noreferrer&quot;&gt;https://www.youtube.com/watch?v=DFP4xl0V0mk&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-07-02T14:45:46.613" LastActivityDate="2014-07-02T14:45:46.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7588" PostTypeId="5" CreationDate="2014-07-02T14:03:53.527" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-02T14:03:53.527" LastActivityDate="2014-07-02T14:03:53.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7589" PostTypeId="4" CreationDate="2014-07-02T14:03:53.527" Score="0" Body="A cockpit featuring electronic/digital instrument displays." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-07-02T14:18:38.807" LastActivityDate="2014-07-02T14:18:38.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7590" PostTypeId="5" CreationDate="2014-07-02T14:07:18.173" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-02T14:07:18.173" LastActivityDate="2014-07-02T14:07:18.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7591" PostTypeId="4" CreationDate="2014-07-02T14:07:18.173" Score="0" Body="USAF is the short for The United States Air Force. It's a branch of the United States Armed Forces. " OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-07-02T14:18:34.427" LastActivityDate="2014-07-02T14:18:34.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7592" PostTypeId="2" ParentId="7585" CreationDate="2014-07-02T14:53:25.173" Score="19" Body="&lt;p&gt;The &lt;a href=&quot;http://www.navair.navy.mil/nawcad/index.cfm?fuseaction=home.content_detail&amp;amp;key=7E0AD2EF-3FAB-41DE-8274-4B99F2404430&quot;&gt;official name&lt;/a&gt; is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_blast_deflector#Aircraft_carriers&quot;&gt;Jet Blast Deflector&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the name suggests, they direct the fast-moving and hot air from the jet engines upwards. This protects the personnel and equipment behind the departing aircraft from getting blown around or damaged from the jet blast. Because of the high temperature of the jet blast, they may have active cooling systems, and must be allowed to cool sufficiently before being used as regular deck again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate the risks, see &lt;a href=&quot;http://www.youtube.com/watch?v=1qkcVGwhzlY&quot;&gt;this video&lt;/a&gt;, which shows a vehicle being blown away by a 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was also a &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/6107110/&quot;&gt;recent event&lt;/a&gt; in Pakistan where a 737 damaged the tarmac (and, as a result, itself) during an engine run-up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make a comparison, each engine on a 737-400 can produce up to &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_Classic#Specifications&quot;&gt;22,000 lbf&lt;/a&gt; (98 kN) of thrust. The Su-33 in your picture has two engines close together which can each produce &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-33#Specifications&quot;&gt;16,750 lbf&lt;/a&gt; (74.5 kN) of thrust, or 28,214 lbf (125.5 kN) with afterburner.  That's a total of 56,248 lbf of thrust in afterburner, or 2.5 times the force of one engine on the 737-400. Of course, this does not directly equate to jet blast or temperatures, but it is a good indicator of the forces involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To provide a better idea of the jet blast, see &lt;a href=&quot;http://profemery.info/aviation/738_blast.htm&quot;&gt;this chart&lt;/a&gt; (based on the 737-800). At 20 m behind the tail (which is about 20 m behind the engines), the jet blast can reach 300 km/hr at takeoff thrust. For more details about jet blast on the 737 series, see the &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737sec6.pdf&quot;&gt;Boeing documentation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CFM56-3 (used on the 737-400) can produce exhaust gas temperature (EGT) of up to &lt;a href=&quot;http://www.b737.org.uk/cfm56_soi.htm&quot;&gt;930 C&lt;/a&gt; at takeoff. This will mix with the cooler bypass air (and ambient air) to reach cooler temperatures further behind the engine. Military jet engines have a smaller bypass ratio, which means there is less of the cool bypass air in the exhaust to mix with the hot core exhaust.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-07-02T14:53:25.173" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7593" PostTypeId="2" ParentId="5177" CreationDate="2014-07-02T16:02:34.290" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.aviationpartnersboeing.com/&quot; rel=&quot;nofollow&quot;&gt;Aviation Partners Boeing&lt;/a&gt;, a joint venture between the two companies, developed the winglets for 737NG, 757 and 767 aircraft.  They are offered in two varieties, a &quot;blended&quot; version, which is where the wingtip is upturned to near vertical and a newer, &quot;split scimitar&quot; version which adds a downward pointing tip as well.  They are made of a composite material with aluminium leading and trailing edges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their purpose is not to generate lift, but rather, prevent wingtip vortices (which generate a significant amount of induced drag) from spilling onto the top of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design characteristics of the blended winglet are described in &lt;a href=&quot;http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&amp;amp;Sect2=HITOFF&amp;amp;d=PALL&amp;amp;p=1&amp;amp;u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&amp;amp;r=1&amp;amp;f=G&amp;amp;l=50&amp;amp;s1=5348253.PN.&amp;amp;OS=PN/5348253&amp;amp;RS=PN/5348253&quot; rel=&quot;nofollow&quot;&gt;US Patent 5,348,253&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-07-02T16:23:06.317" LastActivityDate="2014-07-02T16:23:06.317" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="7594" PostTypeId="2" ParentId="7582" CreationDate="2014-07-02T16:55:26.250" Score="18" Body="&lt;p&gt;To provide more detail, let's look at some actual numbers. Without knowing where you got this information, the term &quot;air pollution&quot; is especially vague. But let's see what we can do. I'll compare CO (carbon monoxide) emissions since I could find that for both cars and jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;noreferrer&quot;&gt;747-8&lt;/a&gt; uses the GEnx-2B67 engine. The older &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400&quot; rel=&quot;noreferrer&quot;&gt;747-400&lt;/a&gt; has a few engine options, one of which is the CF6-80C2B5F. Emissions information about these engines is available from EASA tests, and available for the &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/11GE139%20-%20GEnx-2B67%20TAPS%20%2809.04.2013%29.pdf&quot; rel=&quot;noreferrer&quot;&gt;GEnx&lt;/a&gt; and &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/3GE057%20-%20CF6-80C2B5F%201862M39%20%2809.04.2013%29.pdf&quot; rel=&quot;noreferrer&quot;&gt;CF6&lt;/a&gt;. More info about the tests is &lt;a href=&quot;http://www.ipcc.ch/ipccreports/sres/aviation/107.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on that information the two engines have the following CO emissions at takeoff, reported as grams per kg of fuel burned:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CF6: .05 g/kg CO&lt;/li&gt;&#xA;&lt;li&gt;GEnx: .17 g/kg CO&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The fuel burn rates at takeoff for the engines are reported as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CF6: 2.685 kg/s fuel&lt;/li&gt;&#xA;&lt;li&gt;GEnx: 2.451 kg/s fuel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To find a value of comparison for cars, the EPA standards are &lt;a href=&quot;http://www.epa.gov/otaq/standards/light-duty/tiers0-1-ldstds.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, in units of g/mi. Let's assume that we are using a recent model year, certified to the ULEV (Ultra-Low Emission Vehicles) standard.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ULEV: 1.7 g/mi CO&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now we need a way to compare these values. Let's use your initial value of 5 miles as the comparison distance. The jet engines will remain at takeoff thrust over these 5 miles, and the cars will meet the ULEV standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how long will it take the 747 to cover those 5 miles? Let's look at the whole takeoff run, from a complete stop. This means that it will take about &lt;a href=&quot;http://www.youtube.com/watch?v=cIu0BGtueHI&quot; rel=&quot;noreferrer&quot;&gt;40 seconds&lt;/a&gt; to cover the first mile down the runway. After that, lets assume it averages 160 knots, or 185 mph, over the next 4 miles. This means it will take 78 seconds to cover the rest of the distance, for a total of 118 seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Computing the emissions for the takeoff:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CF6:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{align*}&#xA;2.685\,\mathrm{kg/s} \times 0.05\,\mathrm{g/kg} &amp;amp;= 0.13\,\mathrm{g/s}\text{ CO}\\&#xA;0.13\,\mathrm{g/s}\times 118\,\mathrm{s} &amp;amp;= 15.84\,\mathrm{g} \text{ CO per engine}\\&#xA;15.84\,\mathrm{g}\times 4\text{ engines} &amp;amp;= 63.4\,\mathrm{g}\text{  CO per takeoff.}\end{align*}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GEnx:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{align*}&#xA;2.451\,\mathrm{kg/s} \times 0.17\,\mathrm{g/kg} &amp;amp;= 0.42\,\mathrm{g/s}\text{ CO}\\&#xA;0.42\,\mathrm{g/s}\times 118\,\mathrm{s} &amp;amp;= 49.17\,\mathrm{g}\text{ CO per engine}\\&#xA;49.17\,\mathrm{g}\times 4\text{ engines} &amp;amp;= 196.7\,\mathrm{g}\text{ CO per takeoff.}\end{align*}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The car will be easier to compute:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$5\,\mathrm{mi}\times 1.7\,\mathrm{g/mi} = 8.5\,\mathrm{g}\text{ CO per car.}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747-400 holds 416 people, and the 747-8 holds 467 (3-class configuration). Let's assume each car will carry 4 people. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{align*}&#xA;416/4 &amp;amp;= 104\text{ cars}\\&#xA;467/4 &amp;amp;= 116.75\text{ cars.}&#xA;\end{align*}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We'll split the difference between cramming the three extra people into other cars and adding another car, and just leave it as 116.75 cars. Totaling the emissions from all cars:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{align*}&#xA;104\text{ cars}\times 8.5\,\mathrm{g/car} &amp;amp;= 884\,\mathrm{g}\text{ CO}\\&#xA;116.75\text{ cars}\times 8.5\,\mathrm{g/car} &amp;amp;= 992\,\mathrm{g}\text{ CO.}\end{align*}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So comparing the 747 and the cars:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;747-400: 63.4 g CO&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;104 cars: 884 g CO&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;747-8: 197 g CO&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;116.75 cars: 992 g CO&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So a 747-400 is equivalent to about 7.5 cars, and a 747-8 is equivalent to 23.2 cars, comparing the takeoff run with average vehicle emissions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found this pretty surprising. It would be more fair to compare a takeoff with a drag race or a 0-60 test on the cars, which is probably not what the emissions test requires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anyone has more info or sees an issue with this please let me know.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="946" LastEditDate="2015-04-28T08:46:53.670" LastActivityDate="2015-04-28T08:46:53.670" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7595" PostTypeId="1" AcceptedAnswerId="7596" CreationDate="2014-07-02T16:57:01.530" Score="8" ViewCount="798" Body="&lt;p&gt;In researching for &lt;a href=&quot;https://aviation.stackexchange.com/questions/7582/flight-pollution-on-take-off&quot;&gt;this question&lt;/a&gt;, I came across some &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/11GE139%20-%20GEnx-2B67%20TAPS%20%2809.04.2013%29.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;reports&lt;/a&gt; from EASA referring to TAPS. What is the meaning of TAPS in this context?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-07-05T23:24:28.860" Title="What is TAPS in this report?" Tags="&lt;easa&gt;&lt;terminology&gt;&lt;carbon-footprint&gt;&lt;emissions&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7596" PostTypeId="2" ParentId="7595" CreationDate="2014-07-02T18:50:37.797" Score="7" Body="&lt;p&gt;TAPS means &lt;strong&gt;Twin Annular Premixing Swirler&lt;/strong&gt;, a cyclone mixer / combuster designed to keep the NO&lt;sub&gt;x&lt;/sub&gt; emissions of the General Electric GEnx engines low.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/MO10y.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source: &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/reports/media/TAPS_II_Public_Final_Report.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA report&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/6.2012-936&quot; rel=&quot;noreferrer&quot;&gt;AIAA report&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-07-02T18:56:40.050" LastActivityDate="2014-07-02T18:56:40.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7597" PostTypeId="5" CreationDate="2014-07-02T18:55:11.900" Score="0" Body="&lt;p&gt;Combustion engines emit numerous gasses and particles as exhaust fumes. These emissions impact the environment and contribute to climate change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Amongst the most discussed emissions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CO&lt;sub&gt;2&lt;/sub&gt; - carbon dioxide&lt;/li&gt;&#xA;&lt;li&gt;CO - carbon monoxide&lt;/li&gt;&#xA;&lt;li&gt;NO&lt;sub&gt;x&lt;/sub&gt; - mono-nitrogen oxides&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Emissions are getting an increasing amount of attention, especially in Europe where the EU considered to include aviation in the Emission Trading Scheme. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-07-02T19:20:35.650" LastActivityDate="2014-07-02T19:20:35.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7598" PostTypeId="4" CreationDate="2014-07-02T18:55:11.900" Score="0" Body="For questions related to the emissions of exhaust gasses and particles by aircraft. " OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-07-02T19:20:35.650" LastActivityDate="2014-07-02T19:20:35.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7599" PostTypeId="1" AcceptedAnswerId="7601" CreationDate="2014-07-02T19:37:09.577" Score="24" ViewCount="4921" Body="&lt;p&gt;In Die Hard 2 terrorists take over an airport's ILS and landing lights on a snowy night (visual landing is impossible) and start making threats essentially holding the planes hostage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower immediately sends incoming flights away to the diversion airports and &quot;rack and stack&quot; those already in the landing holding patterns. They also notify the pilots what happened mentioning that after the crisis is over they will start landing planes in order of fuel emergency and that radio may go dead later. Later in the movie the planes in the air actually start running out of fuel and one actually tries to land in the fog. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the protocol when you are a pilot in that situation? Do you just turn to your alternate when you have been circling around for 30 minutes (the &lt;a href=&quot;https://aviation.stackexchange.com/a/3742/609&quot;&gt;&quot;Final reserve fuel&quot;&lt;/a&gt; for commercial jets).&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="19" LastEditDate="2017-09-11T07:35:32.263" LastActivityDate="2021-04-18T18:33:16.357" Title="What happens to incoming flights when the airport shuts down?" Tags="&lt;emergency&gt;&lt;airport&gt;&lt;fuel&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7600" PostTypeId="2" ParentId="7599" CreationDate="2014-07-02T20:06:38.700" Score="17" Body="&lt;p&gt;As Pilot In Command, once you determine your intended destination is unavailable &lt;em&gt;for any reason&lt;/em&gt;, you just switch to your previously determined alternate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the movie the weather is below VFR minimums, so I would expect the pilots to simply switch back to Center frequency &amp;amp; request an immediate diversion to their alternate.  A few might hang around for a short period, but I'm confident all would leave long before they were in any danger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted in the question (&lt;a href=&quot;https://aviation.stackexchange.com/q/3740/52&quot;&gt;Final reserve fuel&lt;/a&gt;) there's no major concern about running out of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note, I've always disliked that movie - the premise that pilots are that stupid goes way beyond &quot;suspension of disbelief&quot;.&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-07-02T20:06:38.700" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7601" PostTypeId="2" ParentId="7599" CreationDate="2014-07-02T20:07:43.760" Score="32" Body="&lt;h2&gt;If a &quot;terrorist takeover&quot; like this were to happen in the real world...&lt;/h2&gt;&#xA;&#xA;&lt;h3&gt;...and the tower still had communication capability:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The tower controllers would advise pilots of the situation, and likely instruct them to return to the Approach frequency to coordinate their next steps (probably a landing at an alternate airport).&lt;br&gt;&#xA;Presumably the tower would still have telephone communication as well, and be able to let Approach know to expect the planes to come back because of the emergency, otherwise the pilots would certainly inform the approach controllers of what's going on when they switch back to that frequency.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;...and the tower has no communication capability:&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;With no response from the tower the usual thing for pilots to do is return to the Approach frequency to find out what's going on. The pilots could elect to attempt a landing anyway, treating the airport as an untowered field (this somewhat famously happened at KDCA, &lt;a href=&quot;http://www.nbcwashington.com/news/local/Air-Traffic-Supervisor-Accused-of-Sleeping-in-the-Tower-118548444.html&quot;&gt;for &lt;em&gt;somewhat different&lt;/em&gt; reasons&lt;/a&gt;), or proceed to an alternate airport.&lt;br&gt;&#xA;If the weather required an instrument approach and the ILS radio signals are not transmitting this would be something the pilots could detect pretty easily (similarly if they were turned off while flying the approach there would be indications in the cockpit that the signal was lost and the pilot would execute the missed-approach procedure), and they would proceed to an alternate airport, again coordinating with the approach controllers.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;...in any case:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;No matter what the situation the aircraft would divert to their alternate airports long before they were in danger of running out of fuel. They would notify ATC of the situation and proceed to an alternate airport. (If not cleared by ATC to proceed to an alternate at some point any sane pilot will declare an emergency for low fuel and proceed on their emergency authority to make a safe landing &lt;em&gt;somewhere&lt;/em&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So basically there's some &quot;artistic liberties&quot; taken in Die Hard 2 in the interest of making it a movie you'd want to sit through.&lt;br&gt;&#xA;A movie where a bunch of terrorists take over an airport and a bunch of flights divert to alternate airports (mildly inconveniencing the passengers) while the National Guard surrounds the airport and deals with the terrorists wouldn't sell nearly as many tickets!&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-07-02T20:16:24.157" LastActivityDate="2014-07-02T20:16:24.157" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="7602" PostTypeId="2" ParentId="7578" CreationDate="2014-07-02T20:32:01.660" Score="9" Body="&lt;p&gt;It depends on how you define &quot;glass cockpit.&quot; Technology has progressed in steps to the modern &quot;glass cockpits&quot; of the latest aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Who developed the first glass cockpits?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The military appears to be the first place where electronic displays were used. First for specific uses like navigation or targeting scopes, and later gaining more functionality.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Which planes first used these glass cockpits?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Blackburn_Buccaneer&quot;&gt;Blackburn Buccaneer&lt;/a&gt; was the first production aircraft with a HUD and entered service in 1963. The North American &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot;&gt;F-111D&lt;/a&gt; was equipped with a multifunction display and entered service in 1970.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The commercial side of the industry took a bit longer to adopt the technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The McDonnell Douglas &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_MD-80&quot;&gt;MD-80&lt;/a&gt; had a glass primary flight display and navigation display, and entered service in &lt;a href=&quot;http://en.wikipedia.org/wiki/Glass_cockpit#History&quot;&gt;1980&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing started work on glass cockpits in the &lt;a href=&quot;http://www.boeing.com/boeing/commercial/history/future_of_flight/glass_cockpit.page&quot;&gt;1970s&lt;/a&gt; while developing the the Supersonic Transport (SST). While the SST never entered production, the work on glass cockpit technology was &lt;a href=&quot;http://www.nasa.gov/centers/langley/news/factsheets/Glasscockpit.html&quot;&gt;used in the design&lt;/a&gt; of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_767&quot;&gt;767&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_757&quot;&gt;757&lt;/a&gt;, entering service in 1982 and 1983, respectively. This was based on work with NASA, including &lt;a href=&quot;http://history.nasa.gov/SP-4216.pdf&quot;&gt;testing on a 737 aircraft&lt;/a&gt; beginning in 1973.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Airbus &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A310&quot;&gt;A310&lt;/a&gt; entered service in 1983, and also used &lt;a href=&quot;http://www.airbus.com/company/history/the-narrative/technology-leaders-1977-1979/&quot;&gt;glass cockpit technology&lt;/a&gt;. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot;&gt;A320&lt;/a&gt;, entering service in 1988, was the first aircraft regarded as having a &quot;full&quot; glass cockpit, replacing traditional instruments for the primary flight instruments.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How was the current layout developed, were other layouts in use beforehand?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The first displays were generally dedicated to specific functions. For commercial aircraft, there was a primary flight display (PFD) showing the pitch and roll of the aircraft. There was also a second display for navigation which displayed the aircraft's heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As RedGrittyBrick points out, adding the speed and altitude to the PFD was natural due to their typical position on either side of the PFD. The use of the vertical &quot;tape&quot; format allows the same visual sense of direction as a round dial while taking up less space in the display.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Was there any resistance or difficulty in getting these systems adopted amongst pilots or their companies?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although there was certainly a sense of caution with the introduction of new technology replacing the most important instruments in the cockpit, the benefits were enough to get the changes adopted. &lt;a href=&quot;http://human-factors.arc.nasa.gov/publications/HF_AdvTech_Aircraft.pdf&quot;&gt;Here is a study&lt;/a&gt; from 1989, focusing on the &quot;glass cockpit&quot; in the 757. It covers the effect on the pilots and their opinions of the new technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The study shows that the pilots had an overall positive view of the new technology, since it reduced their workload and made tasks easier in many situations. However, the report also identified issues with crew members becoming &quot;complacent&quot; due to more automation, and some tasks actually became more difficult with the new systems. There is also the issue of training pilots on the complex new systems, and about what information should be hidden from pilots either during training or in operation of the aircraft. These types of discussions are certainly not going away, as is evidenced by recent events.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-17T19:07:08.830" LastActivityDate="2014-10-17T19:07:08.830" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7603" PostTypeId="2" ParentId="3264" CreationDate="2014-07-02T21:48:05.440" Score="-9" Body="&lt;p&gt;Contact between ATC and Aircraft is purely for Navigation Transmissions and therefore legal. I've never heard them having a general chat other than the odd Merry Christmas Etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion it's general receive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's not illegal to listen to then it's not illegal to pass info on in whatever form, ie web feed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've asked ofcom and if I get a reply will post here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dave&lt;/p&gt;&#xA;" OwnerUserId="2762" LastActivityDate="2014-07-02T21:48:05.440" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7604" PostTypeId="2" ParentId="7548" CreationDate="2014-07-03T07:13:16.163" Score="0" Body="&lt;p&gt;Gate designation that are visible to the outside are important for a number of reasons.  Mainly for Ground Support teams that service aircraft, fuel the planes, mechanics, baggage, and yes even pilots to use to find the correct gate to park upon arrival. &lt;/p&gt;&#xA;" OwnerUserId="2766" LastActivityDate="2014-07-03T07:13:16.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7605" PostTypeId="2" ParentId="1189" CreationDate="2014-07-03T08:49:31.287" Score="3" Body="&lt;p&gt;Just throwing this in as an answer since nobody mentioned it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a light aircraft on a large runway I usually raise the flaps right after touchdown if I actually want to roll FASTER in order to expedite vacating the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the runways where I'm landing have &gt;4 times the LDA that I need, so I'm usually aiming for a quick touchdown before the exit intersection and a quick exit. If I touchdown way before my exit, then raising flaps and letting the a/c continue on the r/w at a fast pace is gladly appreciated by the 737 behind me on short final. &lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-07-03T08:49:31.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7606" PostTypeId="2" ParentId="3264" CreationDate="2014-07-03T09:12:32.363" Score="12" Body="&lt;p&gt;Yes it is illegal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UK's OFCOM, the Independent regulator and competition authority&#xA;for the UK communications industries &lt;a href=&quot;https://web.archive.org/web/20080125220710/http://www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra169.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;write&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Q. Isn't this all a bit heavy?&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A. No. No-one likes their private or business conversations to be&#xA;  listened to. Parliament has passed these laws to protect the privacy&#xA;  of radio users&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Obviously this appears pretty futile to many people, me included.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practicality or enforceability of law is not an issue that prevents legislation. There are other laws that are more obviously justifiable but which relate to actions that are equally difficult to prevent.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2020-05-28T18:16:11.430" LastActivityDate="2020-05-28T18:16:11.430" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7607" PostTypeId="1" AcceptedAnswerId="7611" CreationDate="2014-07-04T04:10:46.397" Score="8" ViewCount="7145" Body="&lt;p&gt;I have seen a couple videos of fighter jets and commercial planes with &lt;a href=&quot;http://en.wikipedia.org/wiki/Head-up_display&quot;&gt;HUD&lt;/a&gt; systems and was wondering how do the heads up displays work?&lt;/p&gt;&#xA;" OwnerUserId="2368" LastEditorUserId="19" LastEditDate="2014-07-04T06:42:26.880" LastActivityDate="2014-07-07T21:01:07.827" Title="How does the HUD Display System work?" Tags="&lt;avionics&gt;&lt;hud&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7609" PostTypeId="5" CreationDate="2014-07-04T07:05:59.963" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-04T07:05:59.963" LastActivityDate="2014-07-04T07:05:59.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7610" PostTypeId="4" CreationDate="2014-07-04T07:05:59.963" Score="0" Body="HUD is the short for head-up display. It's is any transparent display that presents data without requiring users to look away from their usual viewpoints." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-07-04T12:21:33.907" LastActivityDate="2014-07-04T12:21:33.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7611" PostTypeId="2" ParentId="7607" CreationDate="2014-07-04T07:36:14.713" Score="13" Body="&lt;h2&gt;HUD&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The most common form of head-Up Display (&lt;a href=&quot;http://en.wikipedia.org/wiki/Head-up_display#Civil_aircraft_specific_applications&quot; rel=&quot;nofollow noreferrer&quot;&gt;HUD&lt;/a&gt;) is simply an out-of-sight display screen reflected in a transparent flat sheet of glass in the viewers line of sight out the cockpit front window. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The glass sheet is called a combiner. It combines the HUD information with the view out of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are coatings for glass (&lt;a href=&quot;http://www.google.com/patents/US5576886&quot; rel=&quot;nofollow noreferrer&quot;&gt;E.g.&lt;/a&gt;) which allow for reflecting a monochromatic image while allowing transmission of other colors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The display is obviously tailored for that specific use. It must avoid obscuring the view. Therefore it mostly consists of minimal light-colored lines and numerals/letters against a dark background. The dark background allows the pilot to see through the reflection to brighter objects outside - it's a bit like the matt black upper surface typically found on many car dashboards which prevents distracting unwanted images of the top of the dash being reflected into the driver's view out of the windscreen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example from &lt;a href=&quot;http://www.boeing.com/boeing/companyoffices/gallery/images/commercial/737900-11.page&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/s7Pg3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A HUD display is visible on the left in the pilot's line of sight. Above it, mounted on the ceiling is the projector unit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Projector contains optics to make the pilot's view of the display appear to be at infinity (rather than the few feet away it is in reality). This allows the pilot to read the data while their eyes are focused on far-away real-world objects outside the aircraft (runways, weather, other aircraft etc).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;EFVS&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Beyond the projection of basic flight instrument data is the use of HUDs for Enhanced Flight Vision Systems (&lt;a href=&quot;http://aviationweek.com/awin/rockwell-collins-build-end-end-efvs&quot; rel=&quot;nofollow noreferrer&quot;&gt;EFVS&lt;/a&gt;) which provide a kind of augmented reality display that typically uses external infra-red camera systems to identify landmarks (e.g. runway outlines) that may be obscured to the pilot due to fog etc.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-07T21:01:07.827" LastActivityDate="2014-07-07T21:01:07.827" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7612" PostTypeId="1" CreationDate="2014-07-05T17:37:34.187" Score="6" ViewCount="872" Body="&lt;p&gt;I continue to read definitions of MEA as the minimum altitude across the entire segment to ensure obstacle clearance and navigation/comm signal reception. It also states that this is the lowest altitude across the entire segment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I interpret this is that as I fly towards the segment I must be at or above the MEA when I enter the segment to ensure that minimum across the entire segment. Given this why is there a need for MCA (minimum crossing altitude)? The MCA definition requires that minimum altitude at the segment boundary. Why would the MEA not be sufficient?&lt;/p&gt;&#xA;" OwnerUserId="2783" LastEditorUserId="167" LastEditDate="2015-02-21T14:14:37.933" LastActivityDate="2015-02-21T14:14:37.933" Title="What benefit is provided by an MCA that is not already provided by an MEA?" Tags="&lt;aeronautical-charts&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7613" PostTypeId="1" CreationDate="2014-07-05T19:07:36.727" Score="4" ViewCount="98" Body="&lt;p&gt;I am just an aviation enthusiast and wanted to be a pilot someday..&#xA;I just wanted to be able to buy one light aircraft someday..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you tell me what would be the price of a light weight aircraft that can be bought?&#xA;And also the maintenance charges?&#xA;Thank you&lt;/p&gt;&#xA;" OwnerUserId="573" LastActivityDate="2014-07-05T19:07:36.727" Title="Price of a light weight aircraft that can be owned" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-07-05T23:54:27.093" ContentLicense="CC BY-SA 3.0" />
  <row Id="7614" PostTypeId="2" ParentId="7612" CreationDate="2014-07-05T19:10:44.197" Score="7" Body="&lt;p&gt;MCA is for the fix and specifies the minimal altitude at which a normal climb can clear all obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MEA is the for between fixes and assures acceptable navigation signal coverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gLObj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/File:MCAIllustration.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source wikipedia.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MCA can be lower than the MEA of the adjoining route so MEA is required so you won't crash into the next mountain and MEA can also be lower than MCA so it's required so that the pilot can know to climb &lt;em&gt;before&lt;/em&gt; reaching the fix so he knows he can get over the next obstacle safely without needing to circle or zigzag to buy time for the climb.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-07-05T19:10:44.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7615" PostTypeId="2" ParentId="2538" CreationDate="2014-07-05T19:13:15.077" Score="1" Body="&lt;p&gt;I believe &lt;a href=&quot;http://ozrunways.com/&quot; rel=&quot;nofollow&quot;&gt;OzRunways.com&lt;/a&gt; have a VFR package, but it seems to be just for i-devices at the moment.&lt;/p&gt;&#xA;" OwnerUserId="2784" LastEditorUserId="995" LastEditDate="2014-07-07T15:00:07.927" LastActivityDate="2014-07-07T15:00:07.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7616" PostTypeId="1" AcceptedAnswerId="7617" CreationDate="2014-07-06T00:22:20.327" Score="15" ViewCount="5832" Body="&lt;p&gt;Many small aircraft registered in the US seem to have a registration that follows the pattern of N, 4 numbers, and ending in a letter. Sometimes they only have 4 characters, or less. And then there's the FAA Gulfstream &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=1&quot;&gt;N1&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who decides on what the N-Number will be, and are there requirements for how long it should be?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="572" LastEditDate="2015-02-19T09:08:39.740" LastActivityDate="2017-12-28T04:41:47.487" Title="What are the length requirement for US aircraft N-Numbers / registrations?" Tags="&lt;faa-regulations&gt;&lt;aircraft-registration&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7617" PostTypeId="2" ParentId="7616" CreationDate="2014-07-06T02:37:17.453" Score="15" Body="&lt;p&gt;It's not just small aircraft in the US - &lt;em&gt;all&lt;/em&gt; aircraft with US registration follow the same rules. The FAA &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/forming_nnumber/&quot;&gt;has guidelines on how an N number must be formed&lt;/a&gt;. Basically, there are relatively few limits - you can have N + up to 5 characters, up to 2 of which can be letters (at the end).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's what the FAA has to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;U.S. registration numbers may not exceed five characters &lt;strong&gt;in addition&lt;/strong&gt; to the standard U.S. registration prefix letter &lt;strong&gt;N&lt;/strong&gt;. These characters may be:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;One to five numbers (N12345)&lt;/li&gt;&#xA;  &lt;li&gt;One to four numbers followed by one letter (N1234Z)&lt;/li&gt;&#xA;  &lt;li&gt;One to three numbers followed by two letters (N123AZ)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;To avoid confusion with the numbers one and zero, the letters I and O are not to be used.&lt;/p&gt;&#xA;  &#xA;  &lt;h3&gt;Other Requirements&lt;/h3&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;An N-Number may not begin with zero. You must precede the first zero in an N-Number with any number 1 through 9. For example, &lt;strong&gt;N01Z&lt;/strong&gt; is not valid.&lt;/li&gt;&#xA;  &lt;li&gt;Registration numbers &lt;strong&gt;N1&lt;/strong&gt; through &lt;strong&gt;N99&lt;/strong&gt; are strictly reserved for FAA internal use.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When an owner registers an aircraft, they can &lt;a href=&quot;http://aircraft.faa.gov/e.gov/NN/reserve.aspx&quot;&gt;request&lt;/a&gt; an N number, provided it's not already registered. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="65" LastEditDate="2014-07-07T13:30:52.817" LastActivityDate="2014-07-07T13:30:52.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7618" PostTypeId="2" ParentId="7616" CreationDate="2014-07-06T02:39:07.117" Score="4" Body="&lt;p&gt;Per FAA.gov:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An N-number can be in any of these formats&lt;/li&gt;&#xA;&lt;li&gt;One to five numbers (N12345)&lt;/li&gt;&#xA;&lt;li&gt;One to four numbers followed by one letter (N1234Z)&lt;/li&gt;&#xA;&lt;li&gt;One to three numbers followed by two letters (N123AZ)&lt;/li&gt;&#xA;&lt;li&gt;N-numbers do not have&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A zero (0) as the first number&lt;/li&gt;&#xA;&lt;li&gt;The letters &quot;I&quot; or &quot;O&quot;&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;N1-N99 are reserved for the FAA/govt.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Someone who wants to register an aircraft, can either request a specific N number, if it's available, or they can just ask the FAA for a random one.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="946" LastEditDate="2014-07-06T12:17:07.370" LastActivityDate="2014-07-06T12:17:07.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7619" PostTypeId="2" ParentId="2220" CreationDate="2014-07-06T04:51:10.887" Score="2" Body="&lt;p&gt;In the US, you can see most airports income, by going to the FAA site: &lt;a href=&quot;http://cats.airports.faa.gov/Reports/reports.cfm&quot; rel=&quot;nofollow&quot;&gt;&lt;a href=&quot;http://cats.airports.faa.gov/Reports/reports.cfm&quot; rel=&quot;nofollow&quot;&gt;http://cats.airports.faa.gov/Reports/reports.cfm&lt;/a&gt;&lt;/a&gt;. This lets you see the breakdown by year, and revenue sources and costs. Form 127, contains the most detail in the data available there. Running, modifying, and just maintaining an airport, is very expensive.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-07-06T04:51:10.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7620" PostTypeId="1" CreationDate="2014-07-06T08:04:52.457" Score="9" ViewCount="1224" Body="&lt;p&gt;Yesterday I flew in an Swiss Avro RJ100. As soon as we landed I was shocked to see some sort of molten metal which was incandescent and glowing red dripping down from the vent as indicated in the picture. It was almost catching fire! I was suprised to see immediately the maintenance van pitch up to the plane when we didn't even get to a stop. Is this normal? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image isn't of the problem flight, but shows where the problem was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RUUFU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2018-11-12T20:47:31.603" LastActivityDate="2018-11-12T22:42:01.983" Title="What is this molten metal coming from the engine of an Avro RJ 100?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="3" ClosedDate="2018-11-20T08:49:49.240" ContentLicense="CC BY-SA 4.0" />
  <row Id="7621" PostTypeId="2" ParentId="7616" CreationDate="2014-07-06T09:04:48.533" Score="6" Body="&lt;p&gt;Two other answers specify the algorithm for generating valid U.S. aviation IDs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many who view this question might also be interested to learn that the aviation scheme is part of the entire U.S. radio station identifier scheme.  IDs beginning with AA-AL, K, N, and W are allocated to the U.S. (&lt;a href=&quot;https://en.wikipedia.org/wiki/ITU_prefix&quot; rel=&quot;nofollow&quot;&gt;by ITU&lt;/a&gt;).  CF-CK are used in Canada, DA-DR in Germany, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial broadcast stations have all letters (no digits) beginning with W, K, and N; W as the first letter is used for almost all transmitters east of the Mississippi River and (mostly) K to the west.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;U.S. amateur radio operators are assigned IDs with mostly letters with one digit near the front.  They are of the form L[L]DLL[L] where L is a letter and D is a digit (or occasional two digits).  [L] means an optional letter.  The whole ID is 4 or 5 characters.  The digit is assigned by class of license and region according the &lt;a href=&quot;http://wireless.fcc.gov/services/index.htm?id=amateur&amp;amp;job=call_signs_1&quot; rel=&quot;nofollow&quot;&gt;this scheme&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Government, scientific, civil, and other users are assigned by other unique schemes.  For example, the Oregon NOAA weather radio stations (see &lt;a href=&quot;http://www.nws.noaa.gov/nwr/stations.php?State=OR&quot; rel=&quot;nofollow&quot;&gt;table of stations&lt;/a&gt;) all begin with 2 or 3 letters and end with 2 to 4 digits.&lt;/p&gt;&#xA;" OwnerUserId="2015" LastEditorUserId="2015" LastEditDate="2014-07-07T15:20:57.237" LastActivityDate="2014-07-07T15:20:57.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7622" PostTypeId="2" ParentId="7620" CreationDate="2014-07-06T12:27:27.903" Score="4" Body="&lt;p&gt;I do not see anything in your photo, apart the engine that looks perfectly normal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway&#xA;&lt;a href=&quot;http://cs.stanford.edu/people/eroberts/courses/ww2/projects/jet-airplanes/how.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; it is written that the fuel burns at up to 2000 degrees Celsius and the temperature at which metals in this part of the engine start to melt is 1300 degrees Celsius. Hence the metal may melt if something goes wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avro RJ100 has four engines so should be able to land with one inoperative. From the question &lt;a href=&quot;https://aviation.stackexchange.com/questions/7623/would-in-flight-engine-failure-of-the-passenger-jet-be-reported&quot;&gt;I have just asked myself&lt;/a&gt;, it will not be qualified as accident so may not get widely known.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-07-06T13:50:51.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7623" PostTypeId="1" AcceptedAnswerId="7625" CreationDate="2014-07-06T13:18:59.747" Score="16" ViewCount="3954" Body="&lt;p&gt;A passenger plane with two or more engines would probably land without big difficulties with one engine inoperative. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Would the passengers be notified, asking to take the brace position during landing?&lt;/li&gt;&#xA;&lt;li&gt;Would such event have an accident investigation report? &lt;/li&gt;&#xA;&lt;li&gt;Would this report later be available for general public, as are the reports of various significant air disasters? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="917" LastEditorUserId="247" LastEditDate="2014-07-07T05:42:22.280" LastActivityDate="2014-07-15T19:48:59.337" Title="Would in flight engine failure of the passenger jet be reported?" Tags="&lt;emergency&gt;&lt;multi-engine&gt;&lt;engine-failure&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7624" PostTypeId="2" ParentId="7623" CreationDate="2014-07-06T13:41:25.760" Score="10" Body="&lt;p&gt;1) &quot;would probably land without difficulty&quot; - you have it right there.  If there are no other complications, there would be no need to have the pax assume the brace position.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) You may regard this as semantics, but an engine failure followed by a normal landing does not meet the FAA definition of an accident.  Would it be reported to the airline maintenance folks and the FAA as a matter of routine?  Of course.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) See #2.  Since the scenario as presented doesn't rise to the level of an accident, there will be no accident report.  This does not rise to the level of a &quot;significant air disaster.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, there are many ways an engine-out situation can lead to an accident with severe consequences.  Then the reports will be flying! (Pun intended...)  Google 'Captain Al Haynes United Flight 232' for one example.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="167" LastEditDate="2014-07-07T06:42:38.323" LastActivityDate="2014-07-07T06:42:38.323" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7625" PostTypeId="2" ParentId="7623" CreationDate="2014-07-07T04:28:20.320" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;To certify any Commercial Jet Plane worthy of flying,&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a 2 engine plane must be able fly with just 1 engine running  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a 3 engine jet like the Lockheed L1011 or DC10 with just 1&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a 4 engine jet with just 2. Although not a requirement, the 747, A380  could fly on one engine but are not be able to maintain the cruise altitude indefinitely and will eventually become  long-range gliders so they must land immediately.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The landing approach and procedures vary on how much the plane weighs prior to landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Would the passengers be notified, asking to take the brace position during landing?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Brace Positions are only assumed on impact emergencies, like crash landings. Losing an engine doesn't mean you are going to crash so no brace will be assumed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Would such event have an accident investigation report?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will be an investigation but if the plane landed safely it wont be filed as an accident. The plane plus the engines passed its FAA, EASA, etc Certification so it may be a number of reasons why the engine malfunctioned, like bad maintenance, faulty parts etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an extract from wikepedia -- &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbine_engine_failure&quot;&gt;http://en.wikipedia.org/wiki/Turbine_engine_failure&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Shut downs that are not engine failures&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Most in-flight shutdowns are harmless and likely to go unnoticed by&#xA;  passengers. For example, it may be prudent for the flight crew to shut&#xA;  down an engine and perform a precautionary landing in the event of a&#xA;  low oil pressure or high oil temperature warning in the cockpit.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, passengers may become quite alarmed by other engine events&#xA;  such as a compressor surge — a malfunction that is typified by loud&#xA;  bangs and even flames from the engine’s inlet and tailpipe. A&#xA;  compressor surge is a disruption of the airflow through a gas turbine&#xA;  engine that can be caused by engine deterioration, a crosswind over&#xA;  the engine’s inlet, ingestion of foreign material, or an internal&#xA;  component failure such as a broken blade. While this situation can be&#xA;  alarming, the condition is momentary and not dangerous. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Other events such as a fuel control fault can result in excess fuel in the engine’s&#xA;  combustor. This additional fuel can result in flames extending from&#xA;  the engine’s exhaust pipe. As alarming as this would appear, at no&#xA;  time is the engine itself actually on fire. Also, the failure of&#xA;  certain components in the engine may result in a release of oil into&#xA;  bleed air that can cause an odor or oily mist in the cabin. This is&#xA;  known as a fume event. The dangers of fume events are the subject of&#xA;  debate in both aviation and medicine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Would this report later be available for general public, as are the reports of various significant air disasters?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends, as you read above the flight deck crew may shut down an engine because of low oil pressure. Would that have significance of becoming public knowledge?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However as an example, if the problem of an engine failure escalates to the manufacturer then the airline may ground the fleet and that then becomes public knowledge and the reason why because the airliner would give media statements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It all depends on the severity of the problem. Like this one that got reported --- &lt;a href=&quot;http://www.b737.org.uk/accident_reports.htm&quot;&gt;http://www.b737.org.uk/accident_reports.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;20 August 2007; B-18616, 737-800, 30175/1182, FF 11 Jul 02, Okinawa,&#xA;  Japan:&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Engine #1 caught fire shortly after docking destroying the aircraft.&#xA;  No fatalities. The cause was the detachment of a slat pylon bolt which&#xA;  fell off and pierced the fuel tank which leaked and ignited. According&#xA;  to the JTSB the washer that should have held the nut in place probably&#xA;  detached during maintenance 6 weeks before the incident. The design of&#xA;  the nut has since been changed to limit the likelihood of detachment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1732" LastEditorUserId="1732" LastEditDate="2014-07-07T16:21:28.467" LastActivityDate="2014-07-07T16:21:28.467" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7626" PostTypeId="1" AcceptedAnswerId="7632" CreationDate="2014-07-07T04:47:36.830" Score="28" ViewCount="10094" Body="&lt;p&gt;I am watching &lt;a href=&quot;http://en.wikipedia.org/wiki/Breaking_Bad_%28season_2%29&quot;&gt;season 2 episode 13 of Breaking Bad&lt;/a&gt; and in the episode it shows that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an air traffic controller, distraught from his daughter's death,&#xA;  causes a mid-air collision, resulting in debris and human remains&#xA;  raining down onto the Whites' residence, as well as the rest of&#xA;  Albuquerque&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is at the very end of the episode and it looks like he has done nothing malicious just forgot to tell something. To me this sounds really surprising that a single human error can cause such damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a programmer, I know that most of the scenes about computers depicted in the movies are complete nonsense. Is this a similar nonsense about aviation or is this really possible?&lt;/p&gt;&#xA;" OwnerUserId="2787" LastEditorUserId="22726" LastEditDate="2019-02-21T04:18:56.897" LastActivityDate="2019-02-21T04:18:56.897" Title="Can a mistake of a single air-traffic controller cause a collision between planes?" Tags="&lt;air-traffic-control&gt;&lt;accidents&gt;&lt;mid-air-collision&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7627" PostTypeId="2" ParentId="7626" CreationDate="2014-07-07T06:56:46.747" Score="15" Body="&lt;p&gt;Looking at this as a deliberate act it is really possible, but it would still take the element of chance to make it work. There is technology designed to prevent such an occurrence:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ATC software. The picture that ATC sees is computer generated with lots of extra information, and it looks for potential collisions and alerts for them. I believe the US system sends both audio and visual cues called &quot;deals&quot;&lt;/li&gt;&#xA;&lt;li&gt;Commercial aircraft above a certain size is almost always equipped with TCAS (Traffic Collision Avoidance System) which will warn pilots about potential collisions and tell them to climb or descend&lt;/li&gt;&#xA;&lt;li&gt;The human eye: pilots are often looking out and may spot a potential conflict&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So a controller wanting to cause a collision could set 2 airplanes without TCAS on a collision course in bad weather or in the dark, then ignore automated conflict messages and cause a very dangerous situation. That doesn't guarantee a collision as there's a lot of airspace up there, so the controller could do all that diligent work and only get a &quot;near miss&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for accidents yes, controller errors have led to collisions in the past. It's usually a cascade of errors rather than a single error. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-07-07T09:51:56.667" LastActivityDate="2014-07-07T09:51:56.667" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7628" PostTypeId="2" ParentId="7626" CreationDate="2014-07-07T07:53:17.467" Score="11" Body="&lt;p&gt;It not only is possible, &lt;a href=&quot;http://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision&quot; rel=&quot;nofollow&quot;&gt;but actually occurred over Southern Germany&lt;/a&gt;.&lt;br&gt;&#xA; Due to another controller resting one controller was watching two workstations. Just before the crash he became aware of the situation an told one plane to descend. Unfortunately TCAS alerted the other plane to descend, too. The first plane ignored the TCAS instruction to climb and both plane collided killing 71 people. The controller was later murdered by a grieving relative. &lt;/p&gt;&#xA;" OwnerUserId="1635" LastEditorUserId="64" LastEditDate="2014-07-09T16:15:22.827" LastActivityDate="2014-07-09T16:15:22.827" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7629" PostTypeId="1" AcceptedAnswerId="7631" CreationDate="2014-07-07T08:45:49.170" Score="16" ViewCount="2268" Body="&lt;p&gt;I was on a recent flight with a fuel emergency, during which the passengers were required to take precautionary measures. &lt;strong&gt;Under what circumstances are the precautionary measures mentioned below required?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane was diverted to a small regional airport apparently unequipped to service the Airbus we were flying in. Though the fuel truck had arrived at the plane and cones had been placed around the aircraft, we waited quite some time for the fire brigade to arrive before the fuel could be pumped. During this time and during the refueling operation, all the doors were opened (in the rain) and the passengers were required to be in our seats with no electronic equipment. Additionally, seatbelts were required to be &lt;strong&gt;unbelted&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuel emergency occurred while we were circled the Atlantic for 45 minutes waiting for the weather to clear up at Miami International Airport. When the alternate airport shut down as well (Fort Lauderdale International Airport) we were diverted to a small airport in West Palm Beach. From what I was told by a crew member after we had landed, we did not have enough fuel reserve to safely make it to Orlando.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Myself and other pasengers were under the impression that the in-the-seats-with-no-belts restriction is standard for refueling with passengers on board, but in &lt;a href=&quot;https://aviation.stackexchange.com/questions/7599/what-happens-when-the-airport-shuts-down&quot;&gt;the comments of another question&lt;/a&gt; I discovered that this is not the case. &lt;strong&gt;What are some likely reasons that these precautions were taken?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident occurred on 2014-05-15 on Iberia 6123 leaving Madrid at 11:50 with a scheduled arrival at Miami at 15:20. I'm pretty sure the plane was an A330 but it &lt;em&gt;might&lt;/em&gt; have been an A320. &lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-11-13T07:59:44.573" Title="Under what conditions are passengers required to take precautionary measures during refueling?" Tags="&lt;emergency&gt;&lt;airport&gt;&lt;passenger&gt;&lt;fuel&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="7630" PostTypeId="1" AcceptedAnswerId="7633" CreationDate="2014-07-07T12:20:59.460" Score="13" ViewCount="4160" Body="&lt;p&gt;I have just seen this video of what has been called a runway incursion at LEBL (my hometown airport). A russian jet initiates a go-around after seeing an argentinian plane crossing runway 02:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=1N5THRSp4hM&quot;&gt;https://www.youtube.com/watch?v=1N5THRSp4hM&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not clear (as of 2014-07-07 1400L) whether ATC gave clearance to cross the runway. Anyway, my understanding is that even with ATC clearance you are required to check for incoming traffic and hold short of the runway if such traffic exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems like the taxiing crew either didn't look for incoming aircraft or they estimated they had enough separation to cross the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is there any regulated separation distance (time/space) that can be used to tell who was responsible for this conflict? It's solely based on pilots' criteria?&lt;/p&gt;&#xA;" OwnerUserId="424" LastEditorUserId="19" LastEditDate="2017-01-16T13:12:17.020" LastActivityDate="2017-01-16T13:12:17.020" Title="Is there a minimum separation between a landing aircraft and another crossing its runway?" Tags="&lt;safety&gt;&lt;ground-operations&gt;&lt;go-around&gt;&lt;incidents&gt;&lt;runway-incursion&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7631" PostTypeId="2" ParentId="7629" CreationDate="2014-07-07T12:23:47.707" Score="14" Body="&lt;p&gt;Doc 965, CAT.OP.MPA.195(b), regarding Refuelling/defuelling with passengers embarking, on board or disembarking, says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For all other types of fuel, necessary precautions shall be taken and the aircraft shall be properly manned by qualified personnel ready to initiate and direct an evacuation of the aircraft by the most practical and expeditious means&#xA;  available.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So no-belts restriction is one of the elements that ensures &quot;expeditious evacuation&quot;. The same goes for keeping the doors open and keeping the passengers in their seats. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the legal requirement is not that specific, probably the detailed procedure (with all the elements you described and others that were not visible for the passengers) can be found in the company Operations' Manual.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-07-07T12:23:47.707" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7632" PostTypeId="2" ParentId="7626" CreationDate="2014-07-07T12:26:43.500" Score="34" Body="&lt;p&gt;I haven't seen the Breaking Bad episode, but in my experience any aviation related scenes in films and series are usually stretching reality beyond the breaking point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But it is possible that a single mistake can cause an accident. The probability of that happening is extremely remote, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically there are a number of safety barriers (also called defensive layers) in the system&lt;sup&gt;(1)&lt;/sup&gt; that prevent any single mistake from developing into a collision. However, every barrier has a small probability of not catching the problem (e.g. due to it not being perfect or being in state of maintenance / failure) so eventually a crash could result from a single mistake. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is often called the Swiss Cheese Model (originally from Reason, J. (1990) Human Error. Cambridge: University Press, Cambridge.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://patientsafetyed.duhs.duke.edu/module_e/swiss_cheese.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ywPqa.gif&quot; alt=&quot;Swiss cheese model illustrated&quot;&gt;&#xA;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an accident happens, sometimes the phrase &quot;all the holes in the Swiss cheese lined up&quot; is heard, and you now know why. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the first hole might be the mistake of a controller, the other holes may not be mistakes but are certainly rare circumstances and flaws in the system.  Accident investigation focuses on identifying these contributing factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision#&quot; rel=&quot;noreferrer&quot;&gt;&amp;#220;berlingen accident&lt;/a&gt; mentioned by Portree Kid, two immediate causes have been identified&lt;sup&gt;(2)&lt;/sup&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The imminent separation infringement was not noticed by ATC in time. The instruction for the TU154M to descend was given at a time when the prescribed separation to the B757-200 could not be ensured any more.&lt;/li&gt;&#xA;  &lt;li&gt;The TU154M crew followed the ATC instruction to descend and continued to do so even after TCAS advised them to climb. This manoeuvre was performed contrary to the generated TCAS RA.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The first cause can be seen as a mistake by the controller, however that mistake could only happen because of a number of contributing factors (systemic causes):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Management and quality assurance of the air navigation service company did not ensure that during the night all open workstations&#xA;  were continuously staffed by controllers.&lt;/li&gt;&#xA;  &lt;li&gt;Management and quality assurance of the air navigation service company tolerated for years that during times of low traffic flow at night only one controller worked and the other one retired to rest.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In addition to the above, the Short Term Conflict Alerting (STCA) system did not display conflicts to the air traffic controller because of maintenance (not listed as a cause in the report, but discussed in the text).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second cause is not a mistake by the crew of the TU154M, but a latent failure in the way ACAS/TCAS II was introduced. Never did anyone give guidance on what to do if the controller and the TCAS gave conflicting instructions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the report this is identified as a systemic cause:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The integration of ACAS/TCAS II into the system aviation was insufficient and did not correspond in all points with the system philosophy. The regulations concerning ACAS/TCAS published by ICAO and as a result the regulations of national aviation authorities, operational and procedural instructions of the TCAS manufacturer and the operators were not standardised, incomplete and partially contradictory.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So while the accident was caused by a single mistake from the controller, there were also many flaws in the system, which all together allowed the mistake to develop into an accident. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(1)&lt;/sup&gt; By &lt;em&gt;system&lt;/em&gt; I mean the aviation system as a whole, not only the air traffic control (computer) systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(2)&lt;/sup&gt; &lt;a href=&quot;http://www.bfu-web.de/EN/Publications/Investigation%20Report/2002/Report_02_AX001-1-2_Ueberlingen_Report.pdf?__blob=publicationFile&quot; rel=&quot;noreferrer&quot;&gt;&amp;#220;berlingen accident report&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="2806" LastEditDate="2014-07-08T17:48:12.540" LastActivityDate="2014-07-08T17:48:12.540" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7633" PostTypeId="2" ParentId="7630" CreationDate="2014-07-07T12:58:21.843" Score="14" Body="&lt;p&gt;When an aircraft has been given a clearance to land on a runway, that runway is exclusively reserved for the landing aircraft. (Except for LAHSO and &quot;land after&quot; operations, where only part of the runway is reserved for the landing aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means that no other aircraft or vehicle should be on that runway. In this case, clearly something went unplanned. Either the crossing aircraft was not given permission to cross, the landing aircraft no clearance to land, or ATC mistakenly cleared both the landing aircraft and the crossing aircraft to access the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots should always check if the runway they are accessing is safe, and in this case the crew of the landing aircraft did apparently observe the incursion and aborted their landing. The crew of the crossing aircraft noticed the landing aircraft a bit late, but you hear their engines spool up as well as they cross. The sound of the go-around thrust arrives second later due to the difference in distance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crossing aircraft seems to be taxiing toward the rising sun so they may have been blinded and missed the fact that they were crossing a runway. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-07-07T12:58:21.843" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7635" PostTypeId="1" AcceptedAnswerId="7637" CreationDate="2014-07-07T18:04:59.120" Score="5" ViewCount="1624" Body="&lt;p&gt;Where can the requirements for US aircraft registration be found?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the penalty for flying an aircraft without a valid registration?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What should someone do if they believe an aircraft to be operating without valid registration, and how could they determine this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Somewhat related to this other question: &#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3534/what-is-the-pilots-obligation-to-verify-a-registration-has-not-expired&quot;&gt;What is the pilot&amp;#39;s obligation to verify a registration has not expired?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-02-23T22:47:48.560" Title="What are the registration requirements for US aircraft?" Tags="&lt;faa-regulations&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7636" PostTypeId="2" ParentId="7635" CreationDate="2014-07-07T18:25:53.943" Score="1" Body="&lt;p&gt;Sounds like you want to read &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr47_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;14 CFR part 47 - Aircraft Registration&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for most penalties with the FAA, it can vary wildly, from a warning if it is a minor or technical infraction, potentially all the way to lifetime loss of license and criminal charges if done deliberately and maliciously.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-07-07T18:25:53.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7637" PostTypeId="2" ParentId="7635" CreationDate="2014-07-07T18:28:26.127" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Where can the requirements for US aircraft registration be found?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The registration procedure is outlined in &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/aircraft_regn_forms/&quot; rel=&quot;nofollow&quot;&gt;FAA Form AFS-750-94, Information to Aid in the Registration of U.S. Civil Aircraft&lt;/a&gt;. See also the &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/aircraft_regn_forms/&quot; rel=&quot;nofollow&quot;&gt;full list of FAA registration forms&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;3.&lt;/strong&gt; The owner of an aircraft must apply to the Aircraft Registration Branch, P.O. Box 25504, Oklahoma City, Oklahoma 73125-0504, to obtain a certificate of registration. The applicant must submit an Aircraft Registration Application, AC Form 8050-1, accompanied by evidence of ownership and a $5 registration fee.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Requirements for registration of aircraft&lt;/strong&gt; are contained in the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr47_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;Federal Aviation Regulations, Part 47, “Aircraft Registration.”&lt;/a&gt; (For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.) &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, the registrant (whether an individual or a corporation, trustee, etc., all of which are defined in Part 47) must be able to prove legal ownership of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the penalty for flying an aircraft without a valid registration?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The violator would be subject to any of the &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/FAA-Enforcement/FAA-Enforcement&quot; rel=&quot;nofollow&quot;&gt;standard FAA enforcement actions&lt;/a&gt;: administrative action (a &quot;Warning Notice&quot; or &quot;Letter of Correction&quot; which goes on your record), reexamination (&quot;709 ride&quot;), certification action (suspension or revocation), or civil/criminal penalties. The exact penalty would likely depend on the circumstances: whether the violation was intentional and the degree of the pilot's negligence under the FARs.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What should someone do if they believe an aircraft to be operating without valid registration, and how could they determine this?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/contact/&quot; rel=&quot;nofollow&quot;&gt;FAA's website recommends&lt;/a&gt; reporting FAR violations by calling the FAA's toll-free telephone number, &lt;strong&gt;1-866-TELL-FAA&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2014-07-07T18:28:26.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7638" PostTypeId="1" CreationDate="2014-07-07T19:11:08.540" Score="4" ViewCount="1171" Body="&lt;p&gt;I have googled a little about the type of security screening done to hold and hand luggage.  From what I have seen the hold luggage is clearly subject to more rigorous screening, including tomography should it raise suspicion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in light of the recent announcement for passengers to travel with charged mobile devices and be able to switch them on, I have become slightly confused as to why an explosive device would not cause an issue in the hold (I presume passengers won't be asked to remove all electrical items from their hold luggage and switch it on!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the feeling that a small explosive device could do more damage in the main cabin, whereas in the hold the aeroplane's structure would absorb it?  Or is there really a &quot;foolproof&quot; way for the hold luggage scanners to detect whatever is being searched for ?&lt;/p&gt;&#xA;" OwnerUserId="1270" LastEditorUserId="19" LastEditDate="2015-02-23T12:52:44.687" LastActivityDate="2015-02-23T12:52:44.687" Title="What are the differences between hand and hold luggage screening?" Tags="&lt;safety&gt;&lt;security&gt;&lt;tsa&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7639" PostTypeId="1" AcceptedAnswerId="19383" CreationDate="2014-07-07T19:47:13.210" Score="26" ViewCount="1710" Body="&lt;p&gt;Here is something which I did not find in any book, but confirmed in several wind tunnel and flight tests: A T-tail causes a strong nose-down moment in sideslip. This can even be observed in a potential flow analysis, so no fancy viscous effects should be required for an explanation. But I have never understood &lt;strong&gt;why&lt;/strong&gt; it happens. I would even have an explanation for a pitch-up, but the pitch-down really has me puzzled. Does someone here know more?&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="22726" LastEditDate="2019-10-06T01:02:25.427" LastActivityDate="2019-10-06T01:02:25.427" Title="Why does a T-tail produce a pitch-down moment in sideslip?" Tags="&lt;aerodynamics&gt;&lt;sideslip&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7640" PostTypeId="1" CreationDate="2014-07-08T05:57:08.797" Score="3" ViewCount="257" Body="&lt;p&gt;The formula in &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0979263816&quot; rel=&quot;nofollow&quot;&gt;Prouty's book&lt;/a&gt; shows &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the blade inertia unit is slung-feet squared &lt;/li&gt;&#xA;&lt;li&gt;rotor kinetic energy unit is foot-pounds &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;if blade's inertia is high, the rotor kinetic energy should be high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, blade inertia and rotor kinetic energy are two different terms for the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;am I right?&lt;/p&gt;&#xA;" OwnerUserId="2800" LastEditorUserId="1289" LastEditDate="2014-07-08T09:18:13.757" LastActivityDate="2014-07-08T14:44:04.653" Title="Helicopter aerodynamics" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-07-09T10:49:27.273" ContentLicense="CC BY-SA 3.0" />
  <row Id="7642" PostTypeId="2" ParentId="1431" CreationDate="2014-07-08T11:29:12.490" Score="8" Body="&lt;p&gt;Yes,there is one scenario when they can. At our club we are on the top of a hill and if the ridge is working you can abort the approach close the airbrakes and run over the threshold onto the ridge. In fact our low cable break briefing is land straight ahead or takeoff.&lt;/p&gt;&#xA;" OwnerUserId="2804" LastActivityDate="2014-07-08T11:29:12.490" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7643" PostTypeId="2" ParentId="7640" CreationDate="2014-07-08T14:44:04.653" Score="7" Body="&lt;p&gt;Blade inertia and rotor kinetic energy are NOT the same thing, but they are related. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blade inertia is a characteristic of the blade. It is a quantity that shows how difficult it is to change the blade speed (either by acceleration or deceleration) The bigger the inertia of the blade, the harder it is to make it move or make it stop once it's moving. It has nothing to do with the speed/RPM of the blade, it has the same value regardless if the rotor is turning or not. It depends on the way the blade is built (how heavy it is and how is its weight distributed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotor kinetic energy depends on inertia AND rotor speed (RPM). So, a rotor when it's stopped has inertia but has no kinetic energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you start turning the rotor you start building kinetic energy in it using power from the engine. If rotor inertia is big, the engine will work harder to accelerate the rotor BUT, if the engine fails in flight the bigger inertia will oppose RPM decay giving the pilot more time to perform the proper actions. &lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-07-08T14:44:04.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7644" PostTypeId="2" ParentId="7638" CreationDate="2014-07-08T15:57:42.567" Score="3" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/7638/difference-between-hand-and-hold-luggage-screening#comment12775_7638&quot;&gt;ratchet freak pointed out&lt;/a&gt; you do have some more flexibility in ensuring that a small cellphone-sized explosive device is positioned to cause maximum damage if it's in your carry-on baggage as opposed to if it's in checked baggage/cargo. As such there is an inherently higher risk here.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Counterbalancing that risk is the fact that we already have good screening tools to detect explosives or other anomalous things (like say knives or tear gas) concealed in what purports to be an electronic device:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Electronic devices are subject to X-Ray inspection.&lt;br&gt;&#xA;Trained operators can spot quite a few anomalies using these &quot;classic&quot; tools (though rechargeable batteries can often look like explosives).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Puffer_machine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Explosive Trace Detection machines&lt;/a&gt; are already a part of security screening.&lt;br&gt;&#xA;There are also swab machines which operate on a similar principle. They are not foolproof (they have false positive results occasionally, and may miss well-packed explosives), but they're a good tool.&lt;/li&gt;&#xA;&lt;li&gt;Airport security has already asks to see suspect devices power on.&lt;br&gt;&#xA;I had an old Compaq laptop with a completely useless battery, and security would let me plug it in if the battery was dead.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These same techniques (and others) are available for use on checked baggage.&lt;br&gt;&#xA;Checked baggage may also be opened for inspection, which could conceivably include powering on any electronic devices in checked baggage (&lt;a href=&quot;http://www.tsa.gov/traveler-information/packing-tip&quot; rel=&quot;nofollow noreferrer&quot;&gt;but note that the TSA recommends you &lt;em&gt;not&lt;/em&gt; pack your electronics in checked baggage&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's worth pointing out that, at least from a technical standpoint, faking a &quot;power-on&quot; is trivial with today's technology. Unless they're making folks do a full functional demonstration of the device in question a motivated individual with malicious intent would have no problem making a device that's mostly filled with explosives but can still &quot;power on&quot; and display a home screen, which makes the additional security benefit here dubious, at least in my estimation.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-07-08T15:57:42.567" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7645" PostTypeId="2" ParentId="7639" CreationDate="2014-07-08T18:11:43.043" Score="2" Body="&lt;p&gt;Loss of aerodynamic lift of the horizontal tailplane (downward force) causes the aircraft to pitch down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A disruption of airflow over the low pressure side of an airfoil has a greater effect on the airfoil's ability to create lift than a similar air flow disruption to the high pressure side of an airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a conventional tail, the wind shadow of the vertical stab affects the high pressure side of the horizontal tailplane (the top surface) which is not as aerodynamically sensitive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a t-tail, the wind shadow of the vertical stab affects the low pressure side (lower surface) of the horizontal tailplane which is the aerodynamically sensitive side causing a greater loss of effectivity of the tailplane.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2014-07-08T18:11:43.043" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7647" PostTypeId="1" AcceptedAnswerId="7648" CreationDate="2014-07-08T20:06:37.677" Score="7" ViewCount="5133" Body="&lt;p&gt;I noticed that the saftey cards on a recent domestic US flight were the &quot;overwater&quot; version. Two questions about this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What qualifies as &quot;overwater&quot;? Is there an official (i.e., FAA) definition?&lt;/li&gt;&#xA;&lt;li&gt;Do airlines really have certain aircraft with booklets that aren't &quot;overwater&quot;? Are they prevented from flying certain routes without the right safety booklets?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2020-05-25T01:27:55.883" Title="What qualifies as &quot;overwater&quot;?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7648" PostTypeId="2" ParentId="7647" CreationDate="2014-07-08T20:42:06.990" Score="2" Body="&lt;p&gt;I think that &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.3.7.3&quot; rel=&quot;nofollow&quot;&gt;14 CFR Section 91.205(b)(12)&lt;/a&gt; defines &quot;overwater&quot;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(12) If the aircraft is operated for hire over water and beyond&#xA;  power-off gliding distance from shore, approved flotation gear readily&#xA;  available to each occupant and, unless the aircraft is operating under&#xA;  part 121 of this subchapter, at least one pyrotechnic signaling&#xA;  device. As used in this section, “shore” means that area of the land&#xA;  adjacent to the water which is above the high water mark and excludes&#xA;  land areas which are intermittently under water.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=cbc152434ab07217a4ec216cffe870a8&amp;amp;node=14:3.0.1.1.7.20.3.29&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR Section 121.573&lt;/a&gt; outlines the passenger briefing requirements for flights with overwater operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§121.573   Briefing passengers: Extended overwater operations. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) In&#xA;  addition to the oral briefing required by §121.571&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a), each&#xA;  certificate holder operating an airplane in extended overwater&#xA;  operations shall ensure that all passengers are orally briefed by the&#xA;  appropriate crewmember on the location and operation of life&#xA;  preservers, liferafts, and other flotation means, including a&#xA;  demonstration of the method of donning and inflating a life preserver.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The certificate holder shall describe in its manual the procedure&#xA;  to be followed in the briefing required by paragraph (a) of this&#xA;  section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) If the airplane proceeds directly over water after takeoff, the&#xA;  briefing required by paragraph (a) of this section must be done before&#xA;  takeoff.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) If the airplane does not proceed directly over water after&#xA;  takeoff, no part of the briefing required by paragraph (a) of this&#xA;  section has to be given before takeoff, but the entire briefing must&#xA;  be given before reaching the overwater part of the flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Lastly, the requirement for printed safety booklets is from &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/121.571&quot; rel=&quot;nofollow&quot;&gt;14 CFR 121.571(b)&lt;/a&gt;  And to answer your last question, it needs to have only information pertinent to the flight, so if the airplane is not going to fly overwater at all, it doesn't need to have it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Each certificate holder must carry on each passenger-carrying&#xA;  airplane, in convenient locations for use of each passenger, printed&#xA;  cards supplementing the oral briefing. Each card must contain&#xA;  information pertinent only to the type and model of airplane used for&#xA;  that flight, including— &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Diagrams of, and methods of operating, the&#xA;  emergency exits; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Other instructions necessary for use of emergency&#xA;  equipment; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) No later than June 12, 2005, for Domestic and Flag&#xA;  scheduled passenger-carrying flights, the sentence, “Final assembly of&#xA;  this airplane was completed in [INSERT NAME OF COUNTRY].”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="132" LastActivityDate="2014-07-08T20:42:06.990" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7649" PostTypeId="1" AcceptedAnswerId="12169" CreationDate="2014-07-09T06:15:54.570" Score="9" ViewCount="380" Body="&lt;p&gt;Title says it all. I don't see this information online anywhere. A breakdown by PPL/CPL would be nice. I have a vague memory of someone telling me 300 but that seems a tad low for a city of 7.5 million.&lt;/p&gt;&#xA;" OwnerUserId="2394" LastEditorUserId="1696" LastEditDate="2015-01-27T22:41:39.223" LastActivityDate="2015-01-29T22:22:42.540" Title="How many pilots are licensed in Hong Kong?" Tags="&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="7650" PostTypeId="2" ParentId="2072" CreationDate="2014-07-09T08:30:25.137" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is rebooting the computer normal before/during flights?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is wrong to write about &quot;the computer&quot; because a modern airliner probably contains hundreds or thousands of microprocessors and microcontrollers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the seat-back information and entertainment systems almost certainly each contain a microprocessor running some embedded operating system. Each of the items of avionics equipment will contain several microprocessors, probably running real-time operating systems that are certified for use in aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Critical avionics systems have the ability to reset themselves if they detect problems - for example they will have hardware-based watchdog timers that will restart a processor or system that isn't showing signs of running it's software normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike a typical desktop computer, I'm pretty certain that critical systems on board an airliner are designed to handle multiple failures and keep working, in a degraded or fall-back mode if necessary.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;most planes have 3 computers&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As I wrote above, large commercial airliners will likely have hundreds or thousands of microprocessors and microcontrollers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;3 computer&quot; idea comes from the use of redundancy in each critical system. Each subsystem may have two, three or more independently created systems with different hardware and with software written by different teams, each doing the same job. An arbitration system compares the outputs and if one of three disagrees, the other two get to determine what happens.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;No, it's not normal part of the pre-flight checklist for the pilot to walk round to the rear of the aircraft, flip a big red switch off and on again and wait for a start-up jingle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the in-flight movie system isn't working, I'd expect someone will try turning it off and on again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a problem with one of the many independent systems in the cockpit, I'd guess it's plausible, in some cases, the pilot or engineer's checklists for the problem include some kind of reset operation.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-07-09T08:30:25.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7651" PostTypeId="1" CreationDate="2014-07-09T08:35:03.597" Score="6" ViewCount="556" Body="&lt;p&gt;Is there an equation which allow us to perfectly match a helix propeller and an engine? I'm looking for an equation that allow me to correctly dimension an helix propeller for my engine. I mean that allow me to maximize efficiency and thrust, calculate the optimal number of blades, the optimal number of rpm, and the maximum rpm of my helix propeller given a certain engine power, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should I ask this question on the physics division of this website?&lt;/p&gt;&#xA;" OwnerUserId="2811" LastEditorUserId="2811" LastEditDate="2014-07-09T18:42:29.610" LastActivityDate="2014-07-09T19:36:00.960" Title="Is there an equation which allow us to perfectly match a helix propeller and an engine?" Tags="&lt;propeller&gt;&lt;theory&gt;&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7652" PostTypeId="1" CreationDate="2014-07-09T09:15:46.317" Score="8" ViewCount="508" Body="&lt;p&gt;The title says pretty much all. I'm visiting Guam very soon and I just found out the FAA is enforcing some rules that are mostly common sense. However, one rule states &lt;em&gt;&quot;the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have read the rules of AMA, but if i'm not registered with them, does this mean I can't fly my quadcopter in US territory? (non-commercial flight)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&#xA;Lu&lt;/p&gt;&#xA;" OwnerUserId="2812" LastEditorUserId="3091" LastEditDate="2014-08-12T09:57:36.407" LastActivityDate="2014-08-12T09:57:36.407" Title="Can foreigner fly model aircraft (quadcopter) in US without being part of an organization (like AMA)?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;&lt;model-aircraft&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7653" PostTypeId="2" ParentId="7550" CreationDate="2014-07-09T13:34:24.247" Score="3" Body="&lt;p&gt;Here are your answers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can standard control for the P2V+ is via the physical remote it comes with, you can also set waypoints via the app (You may take over control at any time)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To see what you are filming and to start and stop recording among many other features, you will want to have the app on a smartphone connected. Everything you need to do this is included when you buy. You don't have to use the app, but I dont see why not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please check out &lt;a href=&quot;https://www.youtube.com/watch?v=GTlPIeYMnEI&quot; rel=&quot;nofollow&quot;&gt;my video&lt;/a&gt; for a full review of its features.&lt;/p&gt;&#xA;" OwnerUserId="2816" LastEditorUserId="65" LastEditDate="2015-02-24T16:45:47.913" LastActivityDate="2015-02-24T16:45:47.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7654" PostTypeId="5" CreationDate="2014-07-09T16:12:30.503" Score="0" Body="" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-07-09T16:12:30.503" LastActivityDate="2014-07-09T16:12:30.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7655" PostTypeId="4" CreationDate="2014-07-09T16:12:30.503" Score="0" Body="Questions about &quot;Model Aircraft&quot; and the regulations which govern them. Model Aircraft are a specific type of unmanned aerial vehicle which are only flown for hobby or recreational (non-commercial) purposes, and flown within the visual line of sight of the operator at all times." OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-07-09T16:12:30.503" LastActivityDate="2014-07-09T16:12:30.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7656" PostTypeId="2" ParentId="7652" CreationDate="2014-07-09T17:43:39.793" Score="3" Body="&lt;p&gt;This answer reflects the referenced rules but does not necessarily include all laws that may apply in this situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wording on the picture included in &lt;a href=&quot;https://aviation.stackexchange.com/a/2852/1696&quot;&gt;this answer&lt;/a&gt; is confusing. If you go to the &lt;a href=&quot;https://beta.congress.gov/bill/112th-congress/house-bill/658/text&quot; rel=&quot;nofollow noreferrer&quot;&gt;wording of the bill&lt;/a&gt;, it says that the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;may not promulgate any rule or regulation regarding a model aircraft, or an aircraft being developed as a model aircraft, if--&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) the aircraft is operated in accordance with a community-&#xA;      based set of safety guidelines and within the programming of a &#xA;      nationwide community-based organization;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So this bill does not prohibit you from doing anything, it just says that the FAA can't make a rule &lt;strong&gt;specifically about model aircraft&lt;/strong&gt; that applies to you as long as you are operating according to those rules. You still must follow any other general rules about aircraft. See the &lt;a href=&quot;http://www.faa.gov/about/initiatives/uas/media/model_aircraft_spec_rule.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;interpretation of the rule&lt;/a&gt;, as linked from the answer on that question, which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Thus, based on the language of the statute, we conclude that aircraft that meet the statutory definition and operational requirements, as described above, would be exempt from future FAA rulemaking action specifically regarding model aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Thus, the rulemaking prohibition would not apply in the case of general rules that the FAA may issue or modify that apply to all aircraft, such as rules addressing the use of airspace (e.g., the 2008 rule governing VFR operations in the Washington, DC area) for safety or security reasons.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The FAA permits aircraft operations below 500 feet when flown over open water and in sparsely populated areas. 14 CFR 91.119(c). Such operations may not be conducted “closer than 500 feet to any person, vessel, vehicle, or structure.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like there are some such &quot;sparsely populated areas&quot; on Guam, which should meet those requirements. Staying at least 5 miles away from the airports would also be a good idea. You can see that the southern end of the island will be your best bet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/S9Txa.png&quot; alt=&quot;5-mile radii around airports on Guam&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that there are also additional military sites there, including one in the south, that may be sensitive to such things.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-07-09T17:43:39.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7657" PostTypeId="2" ParentId="7651" CreationDate="2014-07-09T19:30:34.363" Score="2" Body="&lt;p&gt;Did you try Mark Drela's &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xrotor/&quot; rel=&quot;nofollow&quot;&gt;XROTOR&lt;/a&gt;? I have difficulty with your term &quot;helix&quot;, but that software should do what you ask if your blade loading is not too high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the linked page:&#xA;XROTOR is an interactive program for the design and analysis of ducted and free-tip propellers and windmills. &#xA;It consists of a collection of menu-driven routines which perform various useful functions such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Design of minimum induced loss rotor (propeller or windmill)&lt;/li&gt;&#xA;&lt;li&gt;Prompted input of an arbitrary rotor geometry&lt;/li&gt;&#xA;&lt;li&gt;Interactive modification of a rotor geometry&lt;/li&gt;&#xA;&lt;li&gt;Twist optimization of an arbitrary rotor for minimum induced loss&lt;/li&gt;&#xA;&lt;li&gt;Analysis of a rotor with a wealth of choices of operating parameters &lt;/li&gt;&#xA;&lt;li&gt;Incoming slipstream effects (from an upstream propeller, viscous wake...)&lt;/li&gt;&#xA;&lt;li&gt;Multi-point parameter display&lt;/li&gt;&#xA;&lt;li&gt;Structural analysis and corrections for twist under load&lt;/li&gt;&#xA;&lt;li&gt;Acoustic analysis with dB noise footprint predictions&lt;/li&gt;&#xA;&lt;li&gt;Interpolation of geometry to radii of interest&lt;/li&gt;&#xA;&lt;li&gt;Plotting of geometry, aerodynamic parameters, and performance maps&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-07-09T19:36:00.960" LastActivityDate="2014-07-09T19:36:00.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7658" PostTypeId="1" AcceptedAnswerId="7661" CreationDate="2014-07-10T08:39:42.687" Score="28" ViewCount="7551" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/q/7630/1289&quot;&gt;Is there a minimum separation between a landing aircraft and another crossing its runway?&lt;/a&gt; it was explained that once an aircraft has clearance to land, that runway is reserved for the exclusive use of that aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At busy airports you can usually see a long line of four or more airliners descending a glideslope towards a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iIREk.jpg&quot; alt=&quot;http://cdn.londonreconnections.com/assets/planes.jpg&quot;&gt;&#xA;&lt;sup&gt;Image by &lt;a href=&quot;https://www.flickr.com/photos/nustyr/&quot; rel=&quot;noreferrer&quot;&gt;nustyR AirTeamImages&lt;/a&gt; (found via &lt;a href=&quot;http://www.londonreconnections.com/2012/london-and-its-airports-part-1-putting-the-math-into-aftermath/&quot; rel=&quot;noreferrer&quot;&gt;LondonReconnections&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;noreferrer&quot;&gt;FlightRadar24&lt;/a&gt;, the time between aircraft appears to be of the order of about 85 seconds according to my stopwatch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vuz90.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems as if, by the time the previous aircraft has turned off the runway, the following aircraft has a very short time to obtain clearance or decide to go around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what point is each aircraft given clearance to land by ATC?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2018-12-11T18:27:00.847" Title="When is an aircraft cleared to land?" Tags="&lt;air-traffic-control&gt;&lt;clearance&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7659" PostTypeId="2" ParentId="2443" CreationDate="2014-07-10T08:47:05.890" Score="-1" Body="&lt;p&gt;These personal locator beacons actually operate via the Cospas-Sarsat system of international search &amp;amp; rescue beacons, nothing to do with Iridium which is a commercial system. The have been known to transmit a signal perfectly well through things like a locked metal cabinet in a basement of a house with the antenna retracted and still summon help, in that case by error though.&lt;/p&gt;&#xA;" OwnerUserId="2819" LastActivityDate="2014-07-10T08:47:05.890" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7660" PostTypeId="1" AcceptedAnswerId="7665" CreationDate="2014-07-10T09:10:54.020" Score="23" ViewCount="1711" Body="&lt;p&gt;I came across the following picture on a news site, in a series of 'this day in...' type items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/y1cGW.jpg&quot; alt=&quot;A black and white photograph of balloons&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accompanying text reads (in Dutch)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;22 juni 1975 - In Geldrop werd de Internationale Holland Ballonwedstrijd gehouden. Deelnemers uit zeven landen streden daar om de &lt;em&gt;Trophee du ballon libre&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which translates to&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;22 June 1975 - The International Holland Balloon competition was held in Geldrop. Contestants from seven countries competed for the &lt;em&gt;Trophee du ballon libre&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To my surprise, the balloons are round and are closed at the bottom. What type of balloons are these? They don't seem to be hot air balloons, are they?&lt;/p&gt;&#xA;" OwnerUserId="2556" LastEditorUserId="1467" LastEditDate="2016-05-25T10:37:56.027" LastActivityDate="2020-07-27T16:30:50.330" Title="What kind of balloons are these?" Tags="&lt;aircraft-identification&gt;&lt;balloon&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7661" PostTypeId="2" ParentId="7658" CreationDate="2014-07-10T09:14:44.743" Score="29" Body="&lt;p&gt;Usually, the clearance is given when the runway is clear of traffic or, at least in Europe, when two conditions are met:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduced Runway Separations is in use and the criteria for issuing the landing clearance are met.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The previous traffic will have left the runway when the following aircraft crosses the threshold. (Non-withheld landing clearance)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;321.5 Landing clearance need not be withheld until prescribed separation exists &#xA;  if there is reasonable assurance that the appropriate separation will exist &#xA;  when the aircraft crosses the runway threshold. However, do not clear an &#xA;  aircraft to land before a preceding landing aircraft has crossed the runway &#xA;  threshold.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft can also be made aware to expect a late landing clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearing multiple aircraft to land in a sequence on the localizer is not used in countries operating under ICAO rules. This is more of an FAA procedure, as described in the other answers.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2014-07-11T07:21:15.457" LastActivityDate="2014-07-11T07:21:15.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7662" PostTypeId="1" AcceptedAnswerId="7663" CreationDate="2014-07-10T09:23:46.910" Score="32" ViewCount="59253" Body="&lt;p&gt;When listening to ATC broadcasting (at least for ULLI), phrase &lt;code&gt;&quot;Information &amp;lt;Charlie|India|whiskey|etc.&amp;gt; on board&quot;&lt;/code&gt; may be heard. Charlie, India, Whiskey, etc. refer to &quot;C&quot;, &quot;I&quot;, &quot;W&quot; but what do these codes mean? What kind of information is this?&lt;/p&gt;&#xA;" OwnerUserId="2581" LastEditorUserId="572" LastEditDate="2015-02-19T09:07:49.177" LastActivityDate="2019-10-28T16:11:20.320" Title="What does &quot;Information &lt;letter&gt;&quot; in ATC transmissions mean?" Tags="&lt;air-traffic-control&gt;&lt;atis&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7663" PostTypeId="2" ParentId="7662" CreationDate="2014-07-10T09:41:07.500" Score="48" Body="&lt;p&gt;This is a simple versioning system used in ATIS (Automatic Terminal Information Service).&#xA;ATIS messages contain information about the weather at the airport, runways in use etc. This information is transmitted on a dedicated radio frequency and repeated in a loop. The ATIS messages are updated frequently as the weather or operations at the airport change. Every time a new ATIS message is generated, the letter is changed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example of an ATIS message:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This is Schiphol arrival information &lt;strong&gt;Kilo&lt;/strong&gt;, main landing runway&#xA;  18Right. Transition level 50. Two zero zero degrees, one one knots.&#xA;  Visibility 10 kilometres. Few 1300 feet, scattered 1800 feet, broken&#xA;  2000 feet. Temperature 15, dewpoint 13. QNH 995 hectopascal. No&#xA;  significant change. Contact Approach and Arrival callsign only. End of&#xA;  information &lt;strong&gt;Kilo&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now when for example the temperature or pressure at the airport changes, the ATIS information is updated: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This is Schiphol arrival information &lt;strong&gt;Lima&lt;/strong&gt;, main landing runway&#xA;  18Right. Transition level 50. Two zero zero degrees, one two knots.&#xA;  Visibility 10 kilometres. Few 1300 feet, scattered 1800 feet, broken&#xA;  2000 feet. Temperature 16, dewpoint 13. QNH 994 hectopascal. No&#xA;  significant change. Contact Approach and Arrival callsign only. End of&#xA;  information &lt;strong&gt;Lima&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The flight crew will listen to the ATIS often before they are in contact with the Air Traffic Control of the airport. They note the information in the ATIS, together with the information version letter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On first contact with the airport's Air Traffic Control they will state what version of the ATIS they have listened to. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Schiphol approach, this is KLM1234 with information Lima.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Air Traffic Controller can then determine whether this is the latest version of the ATIS or if there is newer information available that should be passed on to the flight crew. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="36541" LastEditDate="2019-01-10T02:30:55.463" LastActivityDate="2019-01-10T02:30:55.463" CommentCount="13" ContentLicense="CC BY-SA 4.0" />
  <row Id="7664" PostTypeId="2" ParentId="7662" CreationDate="2014-07-10T09:48:22.777" Score="3" Body="&lt;p&gt;The letters refer to ATIS information, which stands for Automatic Terminal Information Service. ATIS messages are broadcast on a loop on a separate frequency from approach and tower frequencies and inform pilots of weather conditions, active runways, runway conditions, and other important data. Each time the information changes a new recording is made and the version letter increments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots listen to this information before contacting the approach/tower frequency so that the controllers don't spend their entire day reciting it over and over again. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-07-10T09:48:22.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7665" PostTypeId="2" ParentId="7660" CreationDate="2014-07-10T09:59:57.327" Score="29" Body="&lt;p&gt;These are gas balloons. Instead of heating the air to reduce its density and providing the buoyancy, these balloons use helium or hydrogen which is lighter than air. Before lifting off, the balloons are kept on the ground by extra weight hanging on the basket. Usually these bags, clearly visible on the picture, are filled with sand.&lt;/p&gt;&#xA;&lt;p&gt;During the flights, the gas will slowly dissipate through the fabric of the balloon reducing the buoyancy of the balloon. By throwing more weight overboard, again sand, the balloon can maintain in the air.&lt;/p&gt;&#xA;&lt;p&gt;Gas balloons have less control in height than hot air balloons. The balloons are more expensive to operate because of the price of helium and to a lesser extent hydrogen.&lt;/p&gt;&#xA;&lt;p&gt;Although gas ballooning is less popular then hot air ballooning, there are a number of gas balloons operating in Europe and the USA.&lt;br /&gt;&#xA;&lt;a href=&quot;https://www.ballonbau.de/index.php?article_id=33&amp;amp;clang=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/glWtc.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Once a year the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gordon_Bennett_Cup_(ballooning)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gordon Bennett race&lt;/a&gt;  is held in which teams compete to fly the longest distance in their gas balloon.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;After some more research into the &lt;em&gt;Trophee du ballon libre&lt;/em&gt; I found this &lt;a href=&quot;https://ntr.nl/Andere-Tijden/20/detail/Ballonrace-om-de-Coupe-Andries-Blitz/WO_NTR_8738538&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Polygoon Journaal&lt;/em&gt; item&lt;/a&gt; of 1976 (in Dutch). It mentions that the balloon is kept afloat by 630 cubic meters hydrogen gas.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="2556" LastEditDate="2020-07-27T16:30:50.330" LastActivityDate="2020-07-27T16:30:50.330" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="7666" PostTypeId="2" ParentId="7658" CreationDate="2014-07-10T10:17:14.237" Score="9" Body="&lt;p&gt;In addition to @SentryRaven's answer, remember that telescopic compression makes that separation seem much smaller than it actually is.&lt;br/&gt;&#xA;Those aircraft are minutes apart, not seconds, the correct amount of time for one to clear the runway and still give the next a chance to abort the landing if needed.&lt;br/&gt;&#xA;In other words, the proximity you perceive from that image is an optical illusion, it's not real.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="900" LastEditDate="2018-07-30T08:38:45.623" LastActivityDate="2018-07-30T08:38:45.623" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7667" PostTypeId="2" ParentId="7658" CreationDate="2014-07-10T13:50:26.627" Score="8" Body="&lt;p&gt;FAA has the following &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0310.html&quot; rel=&quot;noreferrer&quot;&gt;rulings&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Category I aircraft landing behind Category I or II- 3,000 feet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Category II aircraft landing behind Category I or II- 4,500 feet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) When either is a category III aircraft- 6,000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This picture shows the separation of Category I, II and III.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jXG0T.png&quot; alt=&quot;Separation&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-07-10T13:50:26.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7670" PostTypeId="1" AcceptedAnswerId="7672" CreationDate="2014-07-10T16:30:47.393" Score="20" ViewCount="2588" Body="&lt;p&gt;They're mounted underneath each engines on the JU-52. I saw them up close at the museum. Each one consists of bundled half-inch pipes running through the whole length, open at both ends. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JbeAM.jpg&quot; alt=&quot;Ju-52&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="935" LastEditDate="2014-07-10T16:36:50.120" LastActivityDate="2014-07-10T17:11:55.363" Title="What is the purpose of the three cylinders under the engines of the Junkers 52?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7671" PostTypeId="2" ParentId="7662" CreationDate="2014-07-10T16:59:20.263" Score="3" Body="&lt;p&gt;In the US, ATIS info is typically updated hourly - unless something unusual/unpredicted happens that is relevant to approaching or departing aircraft.&#xA;In the US, ATIS broadcasts include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airport Name.&lt;/li&gt;&#xA;&lt;li&gt;Information letter (Alpha, Bravo, Charlie...).&lt;/li&gt;&#xA;&lt;li&gt;Time Hour/Minute in Zulu (GMT) when the observation was made&lt;/li&gt;&#xA;&lt;li&gt;Winds - direction, speed, and sometimes gusts, variability.&lt;/li&gt;&#xA;&lt;li&gt;Sky Condition - cloud cover (clear, few, scattered, broken, overcast) and altitude&#xA;of the layer(s).&lt;/li&gt;&#xA;&lt;li&gt;Barometric Pressure - which is used to set the aircraft's onboard altimeter to an accurate&#xA;reference for the airport it's approaching/departing).&lt;/li&gt;&#xA;&lt;li&gt;Other remarks, such as runway/taxiway closures, lighting or navigational aids down, etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2824" LastEditorUserId="247" LastEditDate="2014-07-11T07:55:25.100" LastActivityDate="2014-07-11T07:55:25.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7672" PostTypeId="2" ParentId="7670" CreationDate="2014-07-10T17:11:55.363" Score="23" Body="&lt;p&gt;The three cylinders hanging below each engine are the oil coolers - &lt;a href=&quot;http://www.avcom.co.za/phpBB3/viewtopic.php?f=1&amp;amp;t=46484&amp;amp;start=140&quot; rel=&quot;noreferrer&quot;&gt;this page has a much closer shot which I've reproduced below&lt;/a&gt;.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zIrcV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zIrcVm.jpg&quot; alt=&quot;JU-52 oil coolers&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Oil enters and exits the cooler through the two vertical lines and swirls around the hollow air channels. The cold air in flight moving through the tubes cools the oil, which is then returned to the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Courtesy of eBay, here's a photo of an old, rusted-out cooler where you can clearly see the air channel tubes inside. (Using an oil cooler in this condition would promptly empty the engine of oil...)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sfuB0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sfuB0.jpg&quot; alt=&quot;Almost-Cutaway oil cooler&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-10T17:11:55.363" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7673" PostTypeId="1" AcceptedAnswerId="7674" CreationDate="2014-07-10T18:55:28.267" Score="12" ViewCount="1811" Body="&lt;p&gt;I'm wondering if a modern fighter jet (Eurofighter, JAS Gripen, F-35 etc.) is allowed to fly when the ejection seats are known not to be in working order.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1696" LastEditDate="2018-04-29T20:09:29.833" LastActivityDate="2018-04-29T20:09:29.833" Title="Are modern fighter jets allowed to fly with an inoperative ejection seat?" Tags="&lt;safety&gt;&lt;fighter&gt;&lt;jet&gt;&lt;ejection-seat&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7674" PostTypeId="2" ParentId="7673" CreationDate="2014-07-10T19:01:02.343" Score="12" Body="&lt;p&gt;That will vary very much from country to country. While civil aviation regulations are very much standardised across the globe through ICAO (of course with local exceptions) and manufacturer's guidance, military aviation is very much the domain of national regulations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically a military jet will be able to fly with an unserviceable ejection seat, so I imagine that some countries under some circumstances allow flying when they don't work. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-07-10T19:06:52.787" LastActivityDate="2014-07-10T19:06:52.787" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7675" PostTypeId="2" ParentId="2183" CreationDate="2014-07-10T19:26:34.520" Score="5" Body="&lt;p&gt;The rulebook for transport category aircraft says&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c60e0d950f5f39165af783427558522a&amp;amp;node=14:1.0.1.3.11.4.175.34&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.729&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;c) Emergency operation. There must be an emergency means for extending the landing gear in the event of—&lt;/p&gt;&#xA;&lt;p&gt;(1) Any reasonably probable failure in the normal retraction system; or&lt;/p&gt;&#xA;&lt;p&gt;(2) The failure of any single source of hydraulic, electric, or equivalent energy supply.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-07-10T19:26:34.520" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7676" PostTypeId="1" AcceptedAnswerId="7677" CreationDate="2014-07-10T20:25:41.413" Score="13" ViewCount="3523" Body="&lt;p&gt;Since the fuselage of a helicopter is affected by downwash from the rotors, how is the pitot static system affected?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="167" LastEditDate="2015-02-21T14:18:07.430" LastActivityDate="2015-02-21T14:18:07.430" Title="How is the pitot/static system of a helicopter affected by rotor downwash?" Tags="&lt;helicopter&gt;&lt;flight-instruments&gt;&lt;pitot-static&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7677" PostTypeId="2" ParentId="7676" CreationDate="2014-07-10T22:59:12.813" Score="7" Body="&lt;p&gt;The pitot tube is not much of a problem - it's your typical pitot tube, pointing forward (toward the nose of the helicopter) to measure forward airspeed. Airspeed is somewhat less important to a helicopter pilot than it is to a fixed wing pilot since lift is generated by swinging the rotor around instead of moving the whole vehicle through the air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The static port requires a little more thought, because it &lt;em&gt;should&lt;/em&gt; be located in an area of &quot;undisturbed air&quot;, and being in rotor wash is certainly not &quot;undisturbed&quot;.&lt;br&gt;&#xA;On the R22 the static port is actually located inside the shell &lt;a href=&quot;http://www.robinsonheli.com/manuals/r22_mm/r22_mm_13.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;per the maintenance manual&lt;/a&gt; and is thus shielded from rotor wash:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/joCoZ.png&quot; alt=&quot;R22 Pitot/Static Diagram from maintenance manual&quot;&gt;&lt;br&gt;&#xA;You could locate the static source in a similar unpressurized-but-shielded compartment in a pressurized helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On other helicopters the static port is on the fuselage as on most aircraft, for example this one is on &lt;a href=&quot;http://hamptonroadsscalemodelers.com/hh-2d-seasprite-helicopter-walkaround/&quot; rel=&quot;nofollow noreferrer&quot;&gt;an HH-2D Seasprite&lt;/a&gt;:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/JMHrQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JMHrQ.jpg&quot; alt=&quot;HH-2D static port&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Note that the static port is slightly recessed on the seasprite to keep it out of direct rotor wash.  Multiple static ports may also be used (again, as you'll find on other aircraft) to give an average static pressure and reduce the effects of rotor wash on the static pressure reading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with all static systems there will still be &lt;em&gt;some&lt;/em&gt; degree of error - no system is measuring truly static air. As long as it's within a reasonable tolerance all the instruments should be able to be calibrated to read correctly though.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2015-01-01T21:09:06.460" LastActivityDate="2015-01-01T21:09:06.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7678" PostTypeId="2" ParentId="7658" CreationDate="2014-07-11T00:03:25.827" Score="11" Body="&lt;p&gt;Also, in the USA, landing clearance can be given to multiple aircraft at once for the same runway- eg. &quot;JetBlue 1203, number two following an Airbus A320 on a two mile final, wind 260 at 8, runway 22 left, cleared to land.&quot; This is called &quot;anticipated separation&quot;, which allows aircraft to get their landing clearance with much more space. However, in Europe @SentryRaven is correct.&lt;/p&gt;&#xA;" OwnerUserId="311" LastActivityDate="2014-07-11T00:03:25.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7679" PostTypeId="2" ParentId="7676" CreationDate="2014-07-11T08:02:31.557" Score="3" Body="&lt;p&gt;To keep matters short I will post below the IAS-CAS graph for an EC 135 helicopter.&lt;img src=&quot;https://i.stack.imgur.com/UOEan.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see the differences are really small for almost all the speed range. At very low speeds and in hover there may be bigger errors, but in those situations you are not looking at airspeed indicator or altimeter, you are looking outside.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-07-11T08:02:31.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7680" PostTypeId="1" AcceptedAnswerId="7682" CreationDate="2014-07-11T08:11:30.603" Score="7" ViewCount="943" Body="&lt;p&gt;In the comments on &lt;a href=&quot;https://aviation.stackexchange.com/a/1334/2524&quot;&gt;this answer&lt;/a&gt; an interesting assertion was made, that you never have a situation in the US where there is no possible alternate airport.  Assuming that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you're flying an aircraft that is normally flown for commercial reasons,&lt;/li&gt;&#xA;&lt;li&gt;you're flying to an airport that normally allows flights to land,&lt;/li&gt;&#xA;&lt;li&gt;you're flying from an airport in the US to another airport in the US,&lt;/li&gt;&#xA;&lt;li&gt;and you're following the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3740/what-are-the-icao-fuel-reserve-requirements/3742#3742&quot;&gt;regulation&lt;/a&gt; that you have to have enough fuel to get to your destination, then fly to your alternate, then stay in the air for another 45 minutes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;is there any combination of aircraft and airports where no alternate landing airport would be possible?&lt;/p&gt;&#xA;" OwnerUserId="2524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-02-22T16:58:17.980" Title="Is there any combination of aircraft and airports where no alternate landing airport would be possible?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="7681" PostTypeId="1" CreationDate="2014-07-11T08:58:55.830" Score="5" ViewCount="656" Body="&lt;p&gt;Apologies for being so broad in the title but this will consist of a couple of questions in one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I'm sure most of use are aware modern commercial aircraft being manufactured no longer incorporate a flight engineer, this role - as far as I know - has been taken over by onboard systems monitored by the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously there are a number of airlines out there flying older aircraft that do require a flight engineer, which airlines still actively hire F/E's? Do airlines still train people for this position or purely rely on hiring people already trained? I'm thinking more along the thought process here of 'When the older F/E's retire, how are they replaced?'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, what happened to the F/E's when this job was phased out? Were they retrained as pilots? Merged into an office job? Flat out dropped from the company?&lt;/p&gt;&#xA;" OwnerUserId="2097" LastActivityDate="2014-07-11T08:58:55.830" Title="Flight engineers - commercial aviation" Tags="&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="11" ClosedDate="2014-07-12T22:16:32.670" ContentLicense="CC BY-SA 3.0" />
  <row Id="7682" PostTypeId="2" ParentId="7680" CreationDate="2014-07-11T13:28:05.850" Score="5" Body="&lt;p&gt;For larger aircraft, likely no. Worst case they can carry enough fuel to return to their origin. If range does became an issue (e.g. Atlanta -&gt; Anchorage) you would just schedule a technical stop somewhere like Yellowknife. Alaska has a ton of small airfields so short-range aircraft would have many alternatives. Wether the alternate has any services is another question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the question asks about US airports only, mainland -&gt; Hawaii would be a possibility. Hawaiian Air's 717 planes already need extra tanks in the fuselage to get to the mainland, so a return flight would be weather-dependent. If you take off from Seattle and several airports close for bad weather after you pass the no-return point your options are rather limited. If the weather is bad enough to close every airport in the islands then channeling Sullenberger won't help much. Unlikely any sane pilot would take off with that kind of forecast, and Hawaii's weather is usually pretty good.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-11T13:28:05.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7684" PostTypeId="1" AcceptedAnswerId="7685" CreationDate="2014-07-11T14:59:36.540" Score="13" ViewCount="66777" Body="&lt;p&gt;When looking at aircraft for purchase online, a lot of acronyms are used.  In particular, the SMOH and SFOH acronyms are thrown around a lot for used aircraft.  What are the differences between these acronyms, and what are their purpose for a potential airplane buyer?&lt;/p&gt;&#xA;" OwnerUserId="21" LastEditorUserId="19" LastEditDate="2016-07-04T12:10:54.277" LastActivityDate="2017-02-28T09:57:26.117" Title="What is the difference between SMOH and SFOH?" Tags="&lt;piston-engine&gt;&lt;aircraft-purchase&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7685" PostTypeId="2" ParentId="7684" CreationDate="2014-07-11T15:19:59.740" Score="16" Body="&lt;p&gt;With many airplanes the longevity of the engine is a major factor in the price of the aircraft. Piston aircraft engines are generally good for 2000 hours of operation before they need to be overhauled, which is almost always painfully expensive. The more life left on the engine the higher the value of the airplane. SMOH and SFOH both have to do with the time since the engine was overhauled, both are in hours:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;SFOH = Since Factory Overhaul&lt;/li&gt;&#xA;&lt;li&gt;SMOH = Since Major Overhaul&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A factory overhaul means that the engine was sent back to the manufacturer for its overhaul, where a major overhaul could be done by anyone. In general factory overhauls are consistently good whereas non-factory overhauls vary more in quality. Factory overhauls are more expensive as a result. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you see an airplane that has 300 hours since overhaul then there's plenty of life left, if you see one that has 1700 hours on the clock you know you are going to have to fork out a lot of cash much sooner, but you can get the airplane much cheaper. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another acronym you may see is SPOH, that is Since Prop Overhaul. Variable pitch propellers also have mandatory servicing requirements, and although less expensive it's still not cheap, so a factor in the cost of the airplane. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-07-11T15:19:59.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7686" PostTypeId="2" ParentId="7684" CreationDate="2014-07-11T15:55:47.933" Score="24" Body="&lt;p&gt;The life of an aircraft engine is measured in hours of operation since some major service was done to it. When looking at ads for planes there are three regulatory terms that you'll see in engine descriptions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;New&lt;/strong&gt; (TSN)&lt;br&gt;&#xA;This one is pretty self explanatory - A brand new engine, produced with all brand new parts that comes to you right from the factory (or an authorized dealer).  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;New engines have a &quot;zero-time&quot; logbook and no operating history because they've never been installed on an aircraft. Usually there's a &quot;test cell run&quot; entry in the logbook, if anything.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Rebuilt&lt;/strong&gt; (There's not a common abbreviation here - I've seen SFRB or SFRM)&lt;br&gt;&#xA;An engine that went back to the factory and was rebuilt to the same production limits as a &lt;em&gt;new&lt;/em&gt; engine. Some of the parts in the engine will be new, some may be used, but all will meet the same standards and specifications  as a new engine.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Only the original manufacturer can &lt;em&gt;rebuild&lt;/em&gt; an engine, and it comes to you with a zero time logbook and no operating history (because a rebuilt engine is done by the factory and is to new-engine limits and may be made up of components from a bunch of other engines there's no way to give it a history, so it's treated the same way new engines are).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Overhauled&lt;/strong&gt; (SMOH or SFOH)&lt;br&gt;&#xA;An engine that has been completely disassembled (the crank case is split and all the parts pulled out), extensively inspected, and reassembled to either &lt;em&gt;service limits&lt;/em&gt; or &lt;em&gt;new limits&lt;/em&gt;. An overhaul usually includes some used parts (frequently from the same engine), and new parts as necessary to meet limits.&lt;br&gt;&#xA;An overhaul can be done by the factory (&quot;SFOH&quot; - Since Factory Overhaul), or by a specialty engine shop, or even by your local A&amp;amp;P mechanic (both &quot;SMOH&quot; - Since Major Overhaul).  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Overhauled engines retain their operating history, and should have a complete set of logbooks since the day the engine was manufactured. Even if the only part that gets reused is the engine case an overhaul is still &quot;the same engine&quot; in the FAA's eyes, so make sure you can trace the full operating history of that engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You will sometimes see another term - &quot;since top overhaul&quot; (STOP or STOH), but this one is not actually defined in the regulations. Generally it means a shop removed and replaced all the cylinders (the &quot;top end&quot;), but did not open the crank case and thus may not have inspected the &quot;bottom end&quot; (crankshaft, camshaft, bearings, etc.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The terms &quot;overhaul&quot; and &quot;rebuild&quot; are defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1ty=HTML&amp;amp;h=L&amp;amp;r=PART&amp;amp;n=pt14.1.43#se14.1.43_12&quot;&gt;14 CFR 43.2&lt;/a&gt;, and further expounded upon in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/780198&quot;&gt;AC 20-62E&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§43.2   Records of overhaul and rebuilding. (a) No person may describe&#xA;  in any required maintenance entry or form an aircraft, airframe,&#xA;  aircraft engine, propeller, appliance, or component part as being&#xA;  overhauled unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Using methods, techniques, and practices acceptable to the&#xA;  Administrator, it has been disassembled, cleaned, inspected, repaired&#xA;  as necessary, and reassembled; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) It has been tested in accordance with approved standards and&#xA;  technical data, or in accordance with current standards and technical&#xA;  data acceptable to the Administrator, which have been developed and&#xA;  documented by the holder of the type certificate, supplemental type&#xA;  certificate, or a material, part, process, or appliance approval under&#xA;  part 21 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may describe in any required maintenance entry or form&#xA;  an aircraft, airframe, aircraft engine, propeller, appliance, or&#xA;  component part as being rebuilt unless it has been disassembled,&#xA;  cleaned, inspected, repaired as necessary, reassembled, and tested to&#xA;  the same tolerances and limits as a new item, using either new parts&#xA;  or used parts that either conform to new part tolerances and limits or&#xA;  to approved oversized or undersized dimensions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There is no difference between a &quot;factory&quot; overhaul and someone else's &quot;major&quot; overhaul - at least according to the regulations: The standards for what constitutes an overhaul are the same.  What is different is who you talk to if the engine breaks (for a factory overhaul you would go back to the factory, for an overhaul by an engine shop you would go to the shop, and for one by your local mechanic you would go talk to the mechanic).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking at a plane which has had an engine overhaul (the vast majority of the used piston GA fleet) you should pay attention to where it was done and the reputation of the overhauler, but given two engines, one overhauled at the Lycoming factory and the other at a reputable shop like Penn Yan Aero, they would generally be considered equivalent.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-01-09T23:50:16.193" LastActivityDate="2015-01-09T23:50:16.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7687" PostTypeId="1" AcceptedAnswerId="7688" CreationDate="2014-07-11T17:10:18.770" Score="21" ViewCount="26616" Body="&lt;p&gt;If I had a plane that could take off and land in a short distance (eg., the &lt;a href=&quot;http://www.skycraftairplanes.com/sd-1-minisport/#specifications&quot;&gt;SD-1 Minisport&lt;/a&gt;), do I have to use a recognized airport in order to land in the US?  Or can I just land anywhere so long as it's class G airspace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FYI, this question is for non-emergencies.  IE., if I just wanted to land there because it was convenient.  &lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2017-04-28T19:58:07.433" Title="Can I land a plane in a field?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7688" PostTypeId="2" ParentId="7687" CreationDate="2014-07-11T18:39:07.393" Score="18" Body="&lt;p&gt;Landowner's permission is always required.  Then check the municipal zoning regulations and the like - city, state regs etc.  Then your insurance company.  If all these points come up green, go do it.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-07-11T18:44:08.583" LastActivityDate="2014-07-11T18:44:08.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7689" PostTypeId="1" CreationDate="2014-07-12T09:43:05.063" Score="11" ViewCount="9108" Body="&lt;p&gt;When I first heard the word air brakes it came to me that maybe the engine start rotating in the opposite direction for that, but since that's not possible, why can't we have an extra engine for air braking?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did I just invent a new braking paradigm?&lt;/p&gt;&#xA;" OwnerUserId="574" LastEditorUserId="11215" LastEditDate="2018-04-18T14:37:48.497" LastActivityDate="2018-04-18T14:37:48.497" Title="Why don't planes have a reverse propeller as air brakes?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7690" PostTypeId="2" ParentId="7689" CreationDate="2014-07-12T11:22:52.850" Score="44" Body="&lt;p&gt;Planes with a variable pitch propeller can have a pitch range which twists the blades such that they provide reverse thrust. This started to become a common feature on high-performance airplanes in the 1930s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all variable-pitch propellers can produce reverse thrust, however. The constant speed props on small propeller aircraft usually don't, because the energy of the plane after touchdown would be too small to justify the added complexity. On big airplanes which need short landing distances (the &lt;a href=&quot;http://en.wikipedia.org/wiki/C-130&quot;&gt;C-130&lt;/a&gt;, for example), they are a standard feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1936, &lt;a href=&quot;https://en.wikipedia.org/wiki/Heinkel&quot;&gt;Heinkel&lt;/a&gt; produced a sleek dive-bomber, complete with retractable landing gear and a reversible pitch propeller which could be used as a dive brake. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_118&quot;&gt;He-118&lt;/a&gt; was test-flown by &lt;a href=&quot;https://en.wikipedia.org/wiki/Ernst_Udet&quot;&gt;Ernst Udet&lt;/a&gt;, who did not pay attention at the briefing and went on to overspeed the airplane in a dive, destroying the prototype in the process. Thus, the clumsy, fixed-gear Ju-87 was chosen to be the &quot;Stuka&quot; and the He-118 would end as an inspiration for Japanese aircraft designers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-6_Porter&quot;&gt;Pilatus PC-6 Turbo Porter&lt;/a&gt; is a favorite with skydivers because it can put the propeller into reverse even in flight. This allows for spectacular descents and enables it to be safely back on the ground before the skydivers it dropped a moment before have landed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As usual, Wikipedia covers the topic well, so here ist the &lt;a href=&quot;http://en.wikipedia.org/wiki/Variable_pitch_propeller&quot;&gt;link&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-10-12T19:25:23.410" LastActivityDate="2016-10-12T19:25:23.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7691" PostTypeId="1" AcceptedAnswerId="7693" CreationDate="2014-06-11T20:08:09.953" Score="19" ViewCount="32709" Body="&lt;p&gt;Is there a maximum height a propeller airplane could fly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some &lt;strong&gt;lower bounds&lt;/strong&gt; for maximum flying altitude:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;12,000m (39,370ft): &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-70&quot;&gt;Antonow An-70&lt;/a&gt;, produced 1994&lt;/li&gt;&#xA;&lt;li&gt;12,310m (40,387ft): &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_C-130J_Super_Hercules&quot;&gt;Lockheed Martin C-130J Super Hercules&lt;/a&gt;, delivered in 2012&lt;/li&gt;&#xA;&lt;li&gt;12,500m (41,010ft): &lt;a href=&quot;https://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot;&gt;Piaggio P.180 Avanti&lt;/a&gt;, production started in 1986&lt;/li&gt;&#xA;&lt;li&gt;29,523m (96,860ft): &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_Helios&quot;&gt;NASA Helios HP01&lt;/a&gt;, record altitude reached in 2001&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Just for comparison: &lt;a href=&quot;https://en.wikipedia.org/wiki/Low_Earth_orbit&quot;&gt;Low earth orbit&lt;/a&gt; is about 160,000m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Upper bounds&lt;/strong&gt;: I don't know. I guess at some point there is not enough air to get lifted.&#xA;And nobody build an airplane with solar cells that flies to space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess important factors for such an upper bound are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Weight of the airplane,&lt;/li&gt;&#xA;&lt;li&gt;Size, shape and speed of the propellers&lt;/li&gt;&#xA;&lt;li&gt;Speed of the propellers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2833" OwnerDisplayName="moose" LastEditorDisplayName="user20435" LastEditDate="2016-09-16T05:03:46.643" LastActivityDate="2021-04-22T05:03:33.637" Title="How high can propeller airplanes fly?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;altitude&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7693" PostTypeId="2" ParentId="7691" CreationDate="2014-07-12T12:55:38.977" Score="21" Body="&lt;p&gt;It is a matter of power source (and engine aspiration in case of air breathing engines), wing loading and aerodynamic efficiency. With current technology, the limit is around 100.000 ft (30 km), as proven by &lt;a href=&quot;http://en.wikipedia.org/wiki/Electric_aircraft#NASA_Pathfinder.2C_Pathfinder_Plus.2C_Centurion.2C_and_Helios&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pathfinder and especially Helios&lt;/a&gt;. I doubt that much more is possible with really useable aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Aerodynamics first: The altitude factor of &lt;span class=&quot;math-container&quot;&gt;$c_l \cdot Ma^2$&lt;/span&gt; tells you how much lift can be produced at a given flight Mach number, and the wing loading then gives you the minimum density for sustained flight. 0.4 is a good value for subsonic &lt;span class=&quot;math-container&quot;&gt;$c_l \cdot Ma^2$&lt;/span&gt;, and 30 kg/m&lt;span class=&quot;math-container&quot;&gt;$^2$&lt;/span&gt; is a feasible wing loading for flight at 30 km. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology/3348#3348&quot;&gt;this answer&lt;/a&gt; for more detail.&lt;/p&gt;&#xA;&lt;p&gt;If the power source needs ambient air (piston engine), the plane needs triple-stage compressors or turbochargers, which have been &lt;a href=&quot;http://en.wikipedia.org/wiki/Grob_Strato_2C&quot; rel=&quot;nofollow noreferrer&quot;&gt;tested up to 20 km altitude&lt;/a&gt; and should be good for maybe 24 km. They are finicky devices; &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_Condor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing Condor&lt;/a&gt; rarely flew at its maximum power because the stages of the turbochargers would oscillate in an alternating sequence of surges. One stage would race ahead, causing the other to surge, which made the first surge and free up the other to race ahead, and so on.&lt;/p&gt;&#xA;&lt;p&gt;Above approximately 24 km, solar-electric propulsion looks like the best option currently. In all cases you can only fly subsonic, so the minimum practical wing loading will limit the maximum altitude. Aircraft like Helios are very delicate already, so they can only be launched in calm weather and are at risk of being blown away by high altitude winds. Payload is minimal, and depending what the aircraft is supposed to do besides flying high will give you a limit on the maximum altitude between 24 and 30 km.&lt;/p&gt;&#xA;&lt;p&gt;Going to orbit in a propeller driven device is completely illusory. There is not enough matter to push against at higher altitudes, and the theoretical propeller diameter would be measured in Kilometers (or miles, if you prefer that unit). The structural mass would be prohibitive. Also, propeller thrust is inversely proportional to flight speed, and there is no way to accelerate with a propeller to escape velocity. The thrust would be just a rounding error away from zero at 7.9 km/s.&lt;/p&gt;&#xA;&lt;p&gt;This speed is required to escape earth's gravity by flying fast enough around it so that the centripetal force equals the aircraft's weight and is called orbital velocity. The higher the orbit becomes, the more energy is required to reach it. In order to gain enough energy, a propeller aircraft would accelerate in the atmosphere to a speed quite a bit higher than the desired orbital velocity and then convert that kinetic energy to potential energy to lift its trajectory above at least 100 km, the internationally recognized altitude where spaceflight starts. Note that this phase of the flight requires inverted flight if the acceleration takes some time. The maximum flight Mach number would need to be maybe 12 or even 15 so this maneuver is possible at all.&lt;/p&gt;&#xA;&lt;p&gt;In short: Going to orbit with a propeller? Forget it!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-04-22T05:03:33.637" LastActivityDate="2021-04-22T05:03:33.637" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="7695" PostTypeId="2" ParentId="7689" CreationDate="2014-07-12T14:53:28.440" Score="29" Body="&lt;p&gt;Peter K&amp;auml;mpf's answer covers the systems that prop planes actually use for reverse thrust.  The alternative presented in the question is a total non-starter for several reasons.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It's a complex and very heavy system.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unless there was somewhere on the centreline you could mount this engine and prop, you'd need not just one of these things but two, for balance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It causes drag while it isn't being used, which is &lt;em&gt;all the time&lt;/em&gt; except immediately after landing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For certification, aircraft have to be able to stop using just the wheel brakes, anyway, since the complexity of reverse thrust systems makes them likely to fail.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-07-12T14:53:28.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7696" PostTypeId="2" ParentId="7673" CreationDate="2014-07-12T21:35:33.747" Score="9" Body="&lt;p&gt;I asked some of the fighter pilots that I know, and they couldn't give me a concrete answer (for the USAF), and I couldn't find a &lt;em&gt;regulation&lt;/em&gt; that states it is grounding. However, I'm  sure it would ground the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.airforcetimes.com/article/20120131/NEWS/201310331/Ejection-seat-parachute-issues-ground-15-F-35s&quot; rel=&quot;noreferrer&quot;&gt;this instance&lt;/a&gt;, fighter jets (F-35s) were grounded for a &amp;quot;relatively&amp;quot; minor issue with the seat:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Fifteen F-35 Joint Strike Fighters will remain grounded for at least five more days because their ejection seat parachutes were installed backwards&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;Even though the parachute was packed backwards, it still would have deployed, but the steering levels on the parachute would have been reversed, making it confusing for a pilot to steer&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Key note there is &lt;em&gt;confusing for the pilot&lt;/em&gt;. The ejection seat was functional, but the fact that it was confusing was enough for it to be grounding. Possibly in wartime it would have been different, but I doubt it.&lt;/p&gt;&#xA;&lt;p&gt;And even in the case that it wasn't grounding, there's no way I (or any of the pilots I talked to) would take that aircraft. It's not worth it.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-07-12T21:35:33.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7697" PostTypeId="1" AcceptedAnswerId="7701" CreationDate="2014-07-13T08:41:27.257" Score="14" ViewCount="7123" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/2873/why-are-the-cockpit-controls-of-airplanes-so-complicated#comment5704_2877&quot;&gt;a comment&lt;/a&gt; to an answer regarding instrumentation complexity, an &quot;energy variometer&quot; was mentioned, labeled in knots. What does this dial actually show, and how does it work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image accompanying the answer in the linked comment was this, with the energy variometer shown at the top left. Don't get distracted by the legs. :)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WK1xt.jpg&quot; alt=&quot;Glider instrument panel&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it is labeled with +- knots, I would assume it is showing rate of change in airspeed (i.e. acceleration), but calling it an &quot;energy variometer&quot; suggests that it is a combination of altitude and airspeed in which case it would show positive when entering updrafts (or when being towed) which is obviously useful for a glider. Either way it would be interesting to know how it works.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-08-15T02:15:56.663" Title="How does an energy variometer work?" Tags="&lt;flight-instruments&gt;&lt;airspeed&gt;&lt;vertical-speed&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7698" PostTypeId="1" AcceptedAnswerId="7700" CreationDate="2014-07-13T12:34:59.673" Score="10" ViewCount="545" Body="&lt;p&gt;I would like to construct a facility next to a private strip.  What are the FAA rules concerning this such as stand off or height?  &lt;/p&gt;&#xA;" OwnerUserId="2836" LastEditorUserId="19" LastEditDate="2014-07-13T18:01:33.297" LastActivityDate="2014-07-13T19:16:06.837" Title="Are there any rules regarding construction near a private strip, such as stand off distance?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7699" PostTypeId="2" ParentId="7697" CreationDate="2014-07-13T14:33:49.980" Score="3" Body="&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Variometer&quot; rel=&quot;nofollow&quot;&gt;variometer&lt;/a&gt; is a similar instrument to as a VSI (Vertical Speed Indicator) or VVI (vertical velocity indicator). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are very important in gliders (what it appears the picture shows), as it indicates the presence of rising or sinking air. In powered flight, they are used to indicate level flight (or set a desired descent rate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders utilize a calibrated variometers (the aforementioned &lt;em&gt;energy variometers&lt;/em&gt;), as an uncalibrated variometer will combine the aircraft's sink rate or rise with the sink rate or rise of the airmass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as how it works,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In most sailplanes, total energy compensation is achieved by connecting the variometer to the atmosphere via a &quot;total energy probe&quot;, that produces vacuum proportional to the square of the glider's air speed—in effect, a negative pitot. Alternatively, the subtraction may be done electronically by the flight computer based on indicated airspeed (pitot).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nadler.com/sn10/Brozel_TE_Compensation_20020510.pdf&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; gives a more detailed explanation, especially as it relates to changes in energy:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A TE variometer doesn't indicate vertical speed. It shows the rate-of-change of the glider's total energy per unit of weight - therefore it's name.&#xA;  It measures the variation of the glider's total energy, which is the sum of&#xA;  potential energy (proportional to altitude) and kinetic energy (proportional&#xA;  to the square of velocity). Its indication can only be regarded as being equal to true vertical speed in the case where kinetic energy does not change, in other words: where the absolute value of velocity (airspeed) remains&#xA;  constant. In contrast, a non-compensated vario will measure the rate of change of potential energy alone, which means the rate of change of altitude, or true vertical speed, independent of whether the glider's velocity changes or not. Conclusion: the two&#xA;  types of variometers indicate the same&#xA;  only when the glider's airspeed does not&#xA;  change. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are looking for an exact formula, &lt;a href=&quot;http://soaringcafe.com/2009/11/total-energy-compensation-explained-part-i/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; shows how to calculate the relation between total energy and pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL; DR&lt;/strong&gt;: The total energy variometer indicates the presence of thermals or other changes in total energy by removing energy 'trades' from the picture (e.g. airspeed for altitude), that would display differently on a normal VSI.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-07-13T14:48:36.717" LastActivityDate="2014-07-13T14:48:36.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7700" PostTypeId="2" ParentId="7698" CreationDate="2014-07-13T19:16:06.837" Score="5" Body="&lt;p&gt;Best is to contact your FAA regional office as the details of the procedures seem to vary a bit depending on your region, and the use of the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/airports/engineering/airspace_analysis/&quot; rel=&quot;noreferrer&quot;&gt;AC70/7460&lt;/a&gt; gives guidance the lighting and lighting of obstructions that may affect the airspace. The first paragraph reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A sponsor proposing any type of construction or alteration of a&#xA;  structure that may affect the National Airspace System (NAS) is&#xA;  required under the provisions of Title 14 Code of Federal Regulations&#xA;  (14 CFR part 77) to notify the FAA by completing the Notice of&#xA;  Proposed Construction or Alteration form (FAA Form 7460-1). The form&#xA;  should be sent to the Obstruction Evaluation service (OES). Copies of&#xA;  FAA Form 7460-1 may be obtained from OES, Airports District Office or&#xA;  FAA Website at &lt;a href=&quot;http://oeaaa.faa.gov&quot; rel=&quot;noreferrer&quot;&gt;http://oeaaa.faa.gov&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More information can be found here   &lt;a href=&quot;http://www.faa.gov/airports/engineering/airspace_analysis/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reporting requirements are laid down in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.2.9#14:2.0.1.2.9.2.1.3&quot; rel=&quot;noreferrer&quot;&gt;CFR 14 part 77 §77.9 &lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-07-13T19:16:06.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7701" PostTypeId="2" ParentId="7697" CreationDate="2014-07-14T08:00:10.067" Score="16" Body="&lt;p&gt;The energy variometer gives the rate change of total energy of the aircraft expressed in vertical knots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A traditional variometer gives the vertical speed of the aircraft derived from the change in barometric pressure. This is very useful for gliding, especially when looking for thermals that lift you up. The problem with ordinary variometers is that they do not indicate why the glider is climbing; is it due to a thermal / ridge wind or is it because the pilot pulled up and the aircraft is losing speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft is climbing in a thermal or ridge wind, the total energy is increasing. When the aircraft is climbing while it is exchanging speed for altitude the total energy is constant (neglecting drag).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Energy equations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total energy is the sum of kinetic energy and potential energy:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$E_{tot} = E_{kin} + E_{pot}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kinetic energy is proportional to the velocity squared:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$E_{kin} = \tfrac{1}{2}mV^2 $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Potential energy is proportional to the height:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$E_{pot} = mgh$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a change in total energy is the result of the changes in kinetic and potential energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\Delta E_{tot} =\Delta  E_{kin} +\Delta  E_{pot}= \tfrac{1}{2}m\Delta(V^2)+mg\Delta h$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Differentiating with respect to time gives:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{\textrm{d}E_{tot}}{\textrm{d}t} =mV\frac{\textrm{d}V}{\textrm{d}t}+mg\frac{\textrm{d}h}{\textrm{d}t}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The climbrate ($\frac{\textrm{d}h}{\textrm{d}t}$) resulting from exchange of kinetic energy to potential energy can be expressed by:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{\textrm{d}h}{\textrm{d}t} = -\frac{V}{g}\frac{\textrm{d}V}{\textrm{d}t}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with $-\frac{\textrm{d}V}{\textrm{d}t}$ being the deceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the correction that is applied to the ordinary variometer to obtain the energy variometer. This can be done in an electronic way but amazingly it can also be done by mechanical pressure measurement.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Total energy and pressure measurements&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we look at pressure measurements that are used to calculate the airspeed, there is a striking similarity to the energy equation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pitot tube facing the incoming airflow measures &lt;em&gt;total pressure&lt;/em&gt; which is the sum of static pressure $P_s$ and the dynamic pressure $q_c$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dynamics pressure, which is the measure for airspeed, is given by &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P_t =P_s+q_c =P_s + \tfrac{1}{2}\rho V^2 $ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that $q_c$ scales proportionally with kinetic energy. The static pressure changes with height but it decrease while potential energy increases. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When mounting the pitot tube backwards with the total pressure port facing backwards, the total pressure measurement would change to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P_t =P_s-q_c =P_s - \tfrac{1}{2}\rho V^2 $ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft trades kinetic energy for height, the speed drops so the term &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$-\tfrac{1}{2}\rho V^2$ would increase in value (becomes less negative). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, the static pressure $P_s$ decreases with the same amount due to the climb. The result is that the total pressure measurement from this aft facing port remains unchanged when the total energy of the aircraft is constant. That is why an aft facing pitot port is called a Total Energy probe (TE probe). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rate of change of the $P_t$ is a direct measure of the rate of change of total energy. So while an ordinary variometer measures rate of change of static pressure, the energy variometer measures rate of change of the total pressure of an aft facing pitot port.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To work best, a TE probe must be in undisturbed air. This is difficult as the probe itself is ahead of the pressure port so there is always some turbulence affecting the measurement. A common approach is to have the probe stick out in front the vertical stabilizer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wstech.de/english/tek_e.htm&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/McKh1.jpg&quot; alt=&quot;TE probe in front of the vertical tail&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure port is at the end of the tube, facing the vertical tail plane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bmum7.jpg&quot; alt=&quot;TE probe port detail&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="9813" LastEditDate="2015-08-15T02:15:56.663" LastActivityDate="2015-08-15T02:15:56.663" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7702" PostTypeId="1" CreationDate="2014-07-14T19:25:09.670" Score="6" ViewCount="1675" Body="&lt;p&gt;I'm working on a project regarding the hydraulics system of the A320 airbus.  I can't seem to find a clear Hi-resolution image of a grounded A320 with the RAT extended out.  Anyone know where I can find one? Or if you have one and don't mind me using it for my project, I'd be much obliged!! Thank you! &lt;/p&gt;&#xA;" OwnerUserId="2839" LastEditorUserId="572" LastEditDate="2015-02-19T09:07:21.430" LastActivityDate="2019-03-20T08:17:05.163" Title="Where can I get a high-res photo of the RAT from an A320 Airbus?" Tags="&lt;turbine&gt;&lt;airbus-a320&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7703" PostTypeId="2" ParentId="7702" CreationDate="2014-07-14T19:29:49.120" Score="12" Body="&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt; is the photo directory of aircraft on the internet, a quick search turns up this beauty :) You can also diversify your search to A318, A319 and A321 since it's in principle the same equipment.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aidyn Iskakov - Almaty Spotting Club&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Air-Astana/Airbus-A320-232/2419974/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airliners.net/photo/Air-Astana/Airbus-A320-232/2419974/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EPo3v.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EPo3v.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/4/7/9/2419974.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-20T08:17:05.163" LastActivityDate="2019-03-20T08:17:05.163" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7704" PostTypeId="2" ParentId="7623" CreationDate="2014-07-14T20:48:51.193" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Would the passengers be notified, asking to take the brace position during landing?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is going to divert, and in most cases it is&lt;sup&gt;1&lt;/sup&gt;, it's not possible to avoid passengers noticing. They will not be asked to assume brace position though, because the landing will be mostly normal on runway with properly deployed landing gear.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Would such event have an accident investigation report?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It will have &lt;strong&gt;incident&lt;/strong&gt; or accident investigation report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accident is defined as occurence causing death, injury or &lt;em&gt;significant&lt;/em&gt; damage to the aircraft &lt;em&gt;except engines or gear&lt;/em&gt;. So most engine failures won't be qualified as accidents (&lt;a href=&quot;http://avherald.com/h?article=4739fcc8&quot; rel=&quot;nofollow&quot;&gt;including some&lt;/a&gt; &lt;a href=&quot;http://avherald.com/h?search_term=uncontained+engine+failure&amp;amp;dosearch=1&quot; rel=&quot;nofollow&quot;&gt;uncontained failures&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They will however be qualified as &lt;strong&gt;serious incidents&lt;/strong&gt;&lt;sup&gt;2&lt;/sup&gt; and those are investigated as well. Reports of such incidents are usually brief, often just paragraph in summary bulletin, but the overseeing authority (in USA that's NTSB) will usually at least want to carefully review the maintenance findings and logs to check for potential signs of systemic or recurring problem.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Would this report later be available for general public, as are the reports of various significant air disasters?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They should be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These incidents rarely appear in mainstream media, but &lt;a href=&quot;http://avherald.com/h?search_term=engine+shut+down+in+flight&amp;amp;dosearch=1&quot; rel=&quot;nofollow&quot;&gt;The Aviation Herald&lt;/a&gt; has a representative selection&lt;sup&gt;3&lt;/sup&gt; of them or you can go to the various sites of the relevant authorities. Authority overseeing the engine manufacturer will usually be involved, so NTSB (USA), AAIB (UK), BEA (France) and MAK (Russia/CIS) will probably cover most, or at least most of the notable, of the incidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;In a 2-engine aircraft engine out is always emergency and requires landing at nearest suitable airport. In aircraft with more engines the flight may be continued but with less thrust the aircraft has to drift to lower flight level and the fuel burn is higher and the flight often has to divert due to fuel shortage (it is not emergency, so it does not warrant using the required fuel reserves).&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;sub&gt;Incidents are rated in several classes. The most severe is class is called &quot;serious incident&quot; and each instance of serious incident gets it's own investigation.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;&lt;sub&gt;Not all, because some authorities are more thorough than other, so the respective countries would look worse when they are actually safer. Explained in &lt;a href=&quot;http://avherald.com/h?article=45483425&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt;, but unfortunately it has no anchors to make direct link. Search for &quot;percent of all daily occurrences&quot;. Canadian TSB is mentioned as most thorough.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-07-15T19:48:59.337" LastActivityDate="2014-07-15T19:48:59.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7705" PostTypeId="1" AcceptedAnswerId="7727" CreationDate="2014-07-14T22:45:38.707" Score="10" ViewCount="3455" Body="&lt;p&gt;On sectional charts (at least in the US) military airports appear with the same symbols as public airports, eg. KBKF.  Some military bases are within restricted airspace.  I would assume all military airports are restricted to public use.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a way to see this on the sectional chart?  Would this information be found in the A/FD?  Is it just assumed that AFB, NAS, etc. indicates military?&lt;/p&gt;&#xA;" OwnerUserId="651" LastEditorUserId="651" LastEditDate="2014-07-15T15:48:20.387" LastActivityDate="2014-11-14T15:03:41.273" Title="Where is it documented an airport is military?" Tags="&lt;airport&gt;&lt;aeronautical-charts&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7706" PostTypeId="2" ParentId="7705" CreationDate="2014-07-14T23:31:32.613" Score="0" Body="&lt;p&gt;If it's a dedicated military airfield, then they do limit what you can do there. If their not busy(basically, nothing based there's flying much), you can often times coordinate to do approaches there, as long as you don't land. If something comes up and you declare an emergency and land, expect to be met by lots of people pointing guns at you, and to be detained for awhile. Transitions are usually easy, to coordinate through talking on the Tower frequency, or talking with the area's approach to go through any airbase delta... usually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;REF: BKF, don't bother with asking for approaches there, due to the tight confines of airspace with DEN, FTG, and APA.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-07-14T23:31:32.613" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7707" PostTypeId="1" AcceptedAnswerId="7716" CreationDate="2014-07-15T04:26:56.270" Score="7" ViewCount="4483" Body="&lt;p&gt;If the maximum aileron deflection possible was commanded on a commercial airliner, how fast would the aircraft roll?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think there's many reasons to bank a large aircraft quickly, but what I want to know is whether it's even possible to roll it at rates such as 10-15 degrees per second or more.&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2016-08-11T14:38:54.470" Title="What's the minimum roll rate a commercial airliner would have with maximum aileron deflection?" Tags="&lt;aircraft-design&gt;&lt;transport-category&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7708" PostTypeId="2" ParentId="7707" CreationDate="2014-07-15T06:39:38.253" Score="3" Body="&lt;p&gt;A320 has maximum rate of roll 25°/s (according to &lt;a href=&quot;http://www.flightglobal.com/pdfarchive/view/1986/1986%20-%202148.html&quot; rel=&quot;nofollow&quot;&gt;this Flight article&lt;/a&gt;). And note that since A320 is fly-by-wire with augmented controls, this is not maximum possible with full aileron deflection but what maximum sidestick deflection will command. Depending on speed full deflection may cause higher rate of roll so the limit is achievable across reasonable range of speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one good reason to roll large aircraft quickly: to counter effect of turbulence. Turbulence can roll even big aircraft pretty quickly (strong turbulence may easily roll the aircraft to more than 45° under a second) and the pilots will want to return it to level quickly to avoid changing direction and loosing much altitude.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-07-15T06:44:58.193" LastActivityDate="2014-07-15T06:44:58.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7709" PostTypeId="2" ParentId="7702" CreationDate="2014-07-15T07:36:54.767" Score="7" Body="&lt;p&gt;Why do you bother looking elsewhere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AIRBUS has its own &lt;a href=&quot;http://www.airbus.com/galleries/photo-gallery/&quot;&gt;Photo gallery&lt;/a&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are not lucky enough  and can't find there what you have been looking, ask them kindly (&lt;a href=&quot;http://www.airbus.com/galleries/photo-gallery/&quot;&gt;Contacts&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nothing beats first hand resources!&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="4234" LastEditDate="2016-03-17T10:59:31.323" LastActivityDate="2016-03-17T10:59:31.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7710" PostTypeId="2" ParentId="7707" CreationDate="2014-07-15T09:42:43.397" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3c238b6691c8e0e97b67c17594420480&amp;amp;node=14:1.0.1.3.10.2.62.32&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;FAA part §23.157&lt;/a&gt; say that&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;in a takeoff configuration (flaps on takeoff landing gear retracted, speed trimmed at 1.2 &lt;span class=&quot;math-container&quot;&gt;$V_{S1}$&lt;/span&gt; or 1.1 &lt;span class=&quot;math-container&quot;&gt;$V_{MC}$&lt;/span&gt; whichever is greater) a roll of 30° must be reversible within 5 seconds for a plane of less than 6.000 pounds up to 10 seconds for planes over 12.500 pounds&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;on approach (flaps in landing position, gear extended, speed trimmed at &lt;span class=&quot;math-container&quot;&gt;$V_{ref}$&lt;/span&gt;) this is reduced to 4 seconds for planes less than 6000 pounds up to 7 for planes over 12500 pounds&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;This is an average roll rate of 6° per second on takeoff and 8° per second on approach on large airplanes.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§23.157   Rate of roll.&lt;/p&gt;&#xA;&lt;p&gt;(a) &lt;em&gt;Takeoff&lt;/em&gt;. It must be possible, using a favorable combination of&#xA;controls, to roll the airplane from a steady 30-degree banked turn&#xA;through an angle of 60 degrees, so as to reverse the direction of the&#xA;turn within:&lt;/p&gt;&#xA;&lt;p&gt;(1) For an airplane of 6,000 pounds or less maximum weight, 5 seconds&#xA;from initiation of roll; and&lt;/p&gt;&#xA;&lt;p&gt;(2) For an airplane of over 6,000 pounds maximum weight, &lt;span class=&quot;math-container&quot;&gt;$\frac{W+500}{1,300}$&lt;/span&gt; seconds, but not more than 10 seconds, where W is the weight in&#xA;pounds.&lt;/p&gt;&#xA;&lt;p&gt;(b) The requirement of paragraph (a) of this section must be met when&#xA;rolling the airplane in each direction with—&lt;/p&gt;&#xA;&lt;p&gt;(1) Flaps in the takeoff position;&lt;/p&gt;&#xA;&lt;p&gt;(2) Landing gear retracted;&lt;/p&gt;&#xA;&lt;p&gt;(3) For a single-engine airplane, at maximum takeoff power; and for a&#xA;multiengine airplane with the critical engine inoperative and the&#xA;propeller in the minimum drag position, and the other engines at&#xA;maximum takeoff power; and&lt;/p&gt;&#xA;&lt;p&gt;(4) The airplane trimmed at a speed equal to the greater of &lt;span class=&quot;math-container&quot;&gt;$1.2 V_{S1}$&lt;/span&gt; or&#xA;&lt;span class=&quot;math-container&quot;&gt;$1.1 V_{MC}$&lt;/span&gt;, or as nearly as possible in trim for straight flight.&lt;/p&gt;&#xA;&lt;p&gt;(c) &lt;em&gt;Approach&lt;/em&gt;. It must be possible, using a favorable combination of&#xA;controls, to roll the airplane from a steady 30-degree banked turn&#xA;through an angle of 60 degrees, so as to reverse the direction of the&#xA;turn within:&lt;/p&gt;&#xA;&lt;p&gt;(1) For an airplane of 6,000 pounds or less maximum weight, 4 seconds&#xA;from initiation of roll; and&lt;/p&gt;&#xA;&lt;p&gt;(2) For an airplane of over 6,000 pounds maximum weight, &lt;span class=&quot;math-container&quot;&gt;$\frac{W+2,800}{2,200}$&lt;/span&gt; seconds, but not more than 7 seconds, where W is the weight in pounds.&lt;/p&gt;&#xA;&lt;p&gt;(d) The requirement of paragraph (c) of this section must be met when&#xA;rolling the airplane in each direction in the following conditions—&lt;/p&gt;&#xA;&lt;p&gt;(1) Flaps in the landing position(s);&lt;/p&gt;&#xA;&lt;p&gt;(2) Landing gear extended;&lt;/p&gt;&#xA;&lt;p&gt;(3) All engines operating at the power for a 3 degree approach; and&lt;/p&gt;&#xA;&lt;p&gt;(4) The airplane trimmed at &lt;span class=&quot;math-container&quot;&gt;$V_{REF}$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-11T14:38:54.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7711" PostTypeId="1" AcceptedAnswerId="7712" CreationDate="2014-07-15T10:04:33.913" Score="26" ViewCount="19111" Body="&lt;p&gt;In case of engine failure, do the fighter jets have such a stable airframe so that they can glide their way through to the nearest landing strip (As it happened in the case of Gimli glider)?&lt;/p&gt;&#xA;" OwnerUserId="2344" LastEditorUserId="1467" LastEditDate="2018-04-27T14:19:36.277" LastActivityDate="2019-09-01T20:09:42.530" Title="Can fighter aircraft glide?" Tags="&lt;aerodynamics&gt;&lt;fighter&gt;&lt;engine-failure&gt;&lt;glider&gt;&lt;stall&gt;" AnswerCount="7" CommentCount="13" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7712" PostTypeId="2" ParentId="7711" CreationDate="2014-07-15T11:33:54.490" Score="42" Body="&lt;p&gt;All airplanes can glide, if they couldn't they wouldn't be able to fly in the first place. When you glide an aircraft you are converting height into airspeed, which you can use to move across the ground. How far you can go across the ground for height lost is called the glide ratio for the aircraft. Gliders have a very high glide ratio as their wings are designed to provide lots of lift at low speeds, fighters have a very low glide ratio as they are designed to provide lift at a much higher speed enabling the fighter to achieve high airspeeds efficiently. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a fighter will glide, it just won't be able to glide that far over the ground. If a fighter has enough altitude to trade for speed and a strip close enough by it can be done (and has been done in the past) by a skilled pilot. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-07-15T16:26:07.347" LastActivityDate="2014-07-15T16:26:07.347" CommentCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="7713" PostTypeId="1" AcceptedAnswerId="7714" CreationDate="2014-07-15T15:30:36.997" Score="14" ViewCount="1958" Body="&lt;p&gt;What are the requirements for an aircraft's tail number to match the registration?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens if an aircraft changes its number? Is it grounded until the new number can be painted on?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="65" LastEditDate="2015-02-23T15:26:06.753" LastActivityDate="2015-02-23T18:52:33.947" Title="Should an aircraft's registration match with its tail number?" Tags="&lt;faa-regulations&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7714" PostTypeId="2" ParentId="7713" CreationDate="2014-07-15T16:12:30.693" Score="18" Body="&lt;p&gt;The registration number painted on the aircraft is required to match the aircraft's registration certificate (and airworthiness certificate). If the numbers don't match the aircraft's paperwork isn't in order, and it can't legally be flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/special_nnumbers/&quot;&gt;There is a procedure for changing your N number&lt;/a&gt; which is usually used to put a &quot;special&quot; (reserved) number on an aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;ol&gt;&#xA;&lt;li&gt;Send the FAA a letter requesting an N number change.&lt;br&gt;&#xA;(It probably helps to have a good reason - like say United Airlines buying a used jet and wanting to re-register it with a &lt;code&gt;N___UA&lt;/code&gt; tail number from their reserved block).&lt;/li&gt;&#xA;&lt;li&gt;Wait for the FAA to send you paperwork authorizing the N number change.&lt;br&gt;&#xA;You will get 3 copies of form 8050-64 - two for the FAA, one for you.&lt;/li&gt;&#xA;&lt;li&gt;Put the new N number on the plane.&lt;br&gt;&#xA;Usually you'd do this by repainting the aircraft (or the portion of the tail where the number is), but you could also do vinyl stickers or something similar)&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of the copies of form 8050-64 becomes your temporary registration certificate at this time, and you must carry that along with your original registration certificate showing the old registraton number.&lt;/li&gt;&#xA;  &lt;li&gt;Within 5 days of applying the new N number return one of the copies of form 8050-64 to the FAA to obtain a new registration certificate with the new N number.&lt;/li&gt;&#xA;  &lt;li&gt;Within 10 days of applying the new N number return the other copy of form 8050-64 to the FAA to obtain a new airworthiness certificate with the new N number.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  I expected to find something stating how long you have between the time the FAA grants the request to change registration numbers and when you must apply the new one to the plane, but as far as I can tell you can take your time doing this: there doesn't seem to be an expiration on the authorization to change N numbers.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As long as you comply with the requirements for the registration number change the aircraft is only &quot;grounded&quot; for as long as it takes to apply the new registration number (if you're repainting this could take a while ; if you apply a large sticker with the new number on it it could be done in less than a day).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-15T16:12:30.693" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7715" PostTypeId="2" ParentId="7711" CreationDate="2014-07-15T19:47:06.120" Score="11" Body="&lt;p&gt;If the shuttle can glide to a landing, so can a fighter aircraft. Gliders have speed brakes to control the glide path angle, and the fighter can vary the angle of attack, which works in much the same way. Also, it can slalom towards the field, so if the pilot picks a landing site close and long enough, the landing is no big problem. Landing gears are normally designed to fall out with gravity alone if the locking mechanism is unlocked. However, I doubt the pilot will be able to deploy all the high lift devices, so the touchdown speed will be rather high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On modern fighter aircraft with artificial stability, the avionics and hydraulic pumps need to work, or the aircraft will not be controllable by a human pilot. In that case, ejection is probably the safest option if all engines fail. If the glide takes more than only a few minutes, hydraulic pressure will have been lost shortly after the engine(s) and any auxiliary power unit (EPU) stop running, and even if the battery-powered flight computer still gives the correct commands, the actuators will not work anymore. Fighters need to be light, so running times of EPUs are only a few minutes, mostly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a successful flare, an aircraft needs a minimum L/D of approximately 5, so it will fly even if no more altitude can be spent during the landing rotation. The only aircraft I ever &quot;met&quot; which did not fulfill this criterium was the European return vehicle project &quot;Hermes&quot; before it got winglets. They were added to make the transition between final approach and touchdown flyable. Hermes was never built, so all these landings happened purely in a computer.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-07-16T23:14:01.607" LastActivityDate="2014-07-16T23:14:01.607" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7716" PostTypeId="2" ParentId="7707" CreationDate="2014-07-15T20:20:32.520" Score="8" Body="&lt;p&gt;The achievable roll rate depends on altitude. At sea level, big aircraft have very low roll rates, because their roll damping is very high due to the large wingspan. Roll damping goes up with the square of the wingspan, whereas the aileron moment grows linearly with wingspan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft flies high enough, the roll rate will go up inversely to the change in density. This is because the flight speed increases inversely with the square root of density, so the same roll rate will cause less change in the local angle of attack on the outer wing (which is the mechanism which causes roll damping). Thus, in 12 km altitude the roll rate will be twice of what it is at sea level (at the same CAS). That is why large airliners have special high-speed ailerons at midspan: They suffice for control, and using the outboard ailerons would stress the wing a lot more. Also, outboard ailerons on high aspect ratio wings cause considerable torsion, such that the wing twist from aileron deflection will reduce aileron effectiveness. Inboard ailerons are much less affected by this effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would wager to say that any airliner will be perfectly capable of 15°/s roll rates if you deflect the outboard ailerons (without overstressing the wings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high altitude research airplane &lt;a href=&quot;http://en.wikipedia.org/wiki/Grob_Strato_2C&quot; rel=&quot;nofollow&quot;&gt;Strato 2C&lt;/a&gt; had a roll rate during approach of only 2°/s! This was no real problem, because the large wing (56.5 m wingspan) would not be affected by gusts when the aircraft flew lower than approx. 30 m. The turbulence is so small scale close to the ground that the gusts would average out over the large wing, and the aircraft calmed down when sinking below 30 m, even in gusty weather. At 18 km altitude, however, it handled almost like a fighter aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-08-11T14:32:08.420" LastActivityDate="2016-08-11T14:32:08.420" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7717" PostTypeId="2" ParentId="7713" CreationDate="2014-07-15T20:33:58.433" Score="4" Body="&lt;p&gt;I think you're also asking about Airline ship numbers (or fleet number, etc). All airline aircraft in the US (and probably most other countries) have to have a registration, and most airlines also have a ship or fleet number. This is the number that's approved on the airlines OpsSpec (Operations Specification, that basically outlines the entire airlines operations, from Diversion airports to numerous other considerations). If what I understand is correct, an airline just lists the aircraft N number, with it's internal number (whatever they want it to be, sometimes a part of the registration, other times completely different). As long as it's documented, and any changes are documented correctly, it doesn't matter how they correlate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the image below, you see the ship numbers on the nose door. The registration would be near the tail, and there are FARs for sizing and placement of that. Also, it's rare that an airline will change the registration or fleet number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RrUaW.jpg&quot; alt=&quot;Ship Numbers&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="65" LastEditDate="2015-02-23T18:52:33.947" LastActivityDate="2015-02-23T18:52:33.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7718" PostTypeId="1" AcceptedAnswerId="7720" CreationDate="2014-07-15T20:49:00.523" Score="6" ViewCount="4160" Body="&lt;p&gt;The graph below shows the landing runway length requirements for a Boeing 747-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BQRkU.png&quot; alt=&quot;Runway length requirements&quot;&gt;&#xA;&lt;sub&gt;(taken from the &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_8.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-8 Airplane Characteristics for Airport Planning&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the fact that the kinetic energy and impulse are directly proportional to the mass, I would have expected this graph to be linear –­ but clearly that's not the case. What is causing the non-linearity here?&lt;/p&gt;&#xA;" OwnerUserId="2846" LastActivityDate="2014-07-15T21:54:29.390" Title="Why is the minimum runway length non-linear in relation to the landing weight?" Tags="&lt;landing&gt;&lt;aircraft-performance&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7720" PostTypeId="2" ParentId="7718" CreationDate="2014-07-15T21:45:59.393" Score="5" Body="&lt;p&gt;While the kinetic energy is proportional to mass, it is not proportional to velocity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The heavier the aircraft is, the higher the landing speed. So the stopping distance increases mainly because of the higher landing speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing two landings, first at mass = $m_1$, the second at mass = $m_2 =1.1 \cdot m_1$, the landing speed will be $\sqrt{\frac{m_2}{m_1}}$ higher during the second landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The kinetic energy during the landing will scale proportional to the square of the mass.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-07-15T21:54:29.390" LastActivityDate="2014-07-15T21:54:29.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7721" PostTypeId="2" ParentId="7711" CreationDate="2014-07-15T22:47:05.410" Score="33" Body="&lt;p&gt;All airplanes can glide. Some glide better than others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very old reference I read talked about engine-out landings in military aircraft. Their procedure was arrive at the airfield at X feet, circle once and land. Trainers like the T-33 needed 2,500 feet, other aircraft needed 3,500-5,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An F-104, which is basically an engine with fins, needed 20,000 feet for the landing loop. So unless you have a flameout in the stratosphere (or directly overtop an airport) you would simply point it at an empty space on the ground and eject.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-15T22:47:05.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7722" PostTypeId="2" ParentId="7711" CreationDate="2014-07-16T00:24:21.003" Score="5" Body="&lt;p&gt;One of the most important things I learned ( in my opinion) when I played around with flight simulators is that all planes can glide. Every aircraft has a &quot;glide plane&quot; which is basically an angle of approach to the ground where you won't stall. The angle depends on the physical characteristics of the plane (wings, etc.). So if you lose power, you can always glide to the ground. The problem is whether your glide plane is wide enough to allow you to reach an airport. You can think of the glide plane as basically telling you that you will drop X feet every Y minutes. So if you want to land at airport you have to time it right (you can also point the nose down to increase speed and approach the ground faster, if you don't have enough glide path left to circle the airport completely.)&lt;/p&gt;&#xA;" OwnerUserId="2849" LastActivityDate="2014-07-16T00:24:21.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7723" PostTypeId="1" AcceptedAnswerId="7724" CreationDate="2014-07-16T00:41:26.137" Score="6" ViewCount="149" Body="&lt;p&gt;How does an FBO refer to the parking spots on the ramp? What is the official term? And is there some sort of an identifier, a &quot;ramp number&quot;? Is this standardized, like runway numbers, or does it vary from FBO to FBO? Are there numbers painted on the ramp?&lt;/p&gt;&#xA;" OwnerUserId="2850" LastActivityDate="2014-07-16T01:08:50.663" Title="How does an FBO refer to the parking spots on the ramp?" Tags="&lt;fbo&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7724" PostTypeId="2" ParentId="7723" CreationDate="2014-07-16T01:08:50.663" Score="4" Body="&lt;p&gt;From the airports I've flown into, it's usually, you're just guided into a spot, and most often, there aren't any lines there, mainly since an FBO should be able to generally serve something as small as a Cessna, to a Gulfstream, or bigger. Flight School Ramps might have painted lines and dedicated parking for their fleet, but they know who will be parking there and what type.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-07-16T01:08:50.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7725" PostTypeId="5" CreationDate="2014-07-16T10:12:36.380" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Fixed-base_operator&quot; rel=&quot;nofollow&quot;&gt;Fixed Base Operators&lt;/a&gt; are business that operate at an airport and offer services to general aviation flights. Basic services commonly include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Refueling&lt;/li&gt;&#xA;&lt;li&gt;Parking or hangaring&lt;/li&gt;&#xA;&lt;li&gt;Arranging rental cars, catering or other conveniences&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Many larger FBOs offer additional services like repairs and maintenance, flight training, aircraft rental, charter flights and so on.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="62" LastEditDate="2015-05-15T20:20:36.117" LastActivityDate="2015-05-15T20:20:36.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7726" PostTypeId="4" CreationDate="2014-07-16T10:12:36.380" Score="0" Body="A Fixed Base Operator (FBO) is a business that offers aviation services at an airport, especially fuel and parking" OwnerUserId="609" LastEditorUserId="62" LastEditDate="2015-05-15T20:20:36.117" LastActivityDate="2015-05-15T20:20:36.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7727" PostTypeId="2" ParentId="7705" CreationDate="2014-07-16T10:59:54.267" Score="5" Body="&lt;p&gt;AFB, MCAS, NAS, CGAS/CGS, and AAF would always be military, yes. BUT the lack of that in the name doesn't mean it's not military... Outside the US especially there's often no such thing to indicate a military base from a civilian field (though AB (for AirBase) is at times used).&lt;br/&gt;&#xA;How do you know? You're supposed to know where you're going when you're flying, and that includes what's off limits to you. &lt;br/&gt;&#xA;&lt;a href=&quot;http://www.post8.org/images/secchart.jpg&quot; rel=&quot;nofollow&quot;&gt;http://www.post8.org/images/secchart.jpg&lt;/a&gt; shows the legend of a sectional (can't inline the image, SO refuses to), which says clearly &quot;All military airports are indicated by abbreviations AFB, NAS, AAF, etc. For complete airport information consult DOD FLIP&quot;. So how do you know? The chart tells you by the name of the facility. It also shows a double ring instead of runway icons as indicating military, but on some charts I looked at that appears to not be consistently applied. &lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-07-16T10:59:54.267" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7728" PostTypeId="1" AcceptedAnswerId="7731" CreationDate="2014-07-16T12:10:12.570" Score="6" ViewCount="1464" Body="&lt;p&gt;In an event of failure of all engines of a commercial aircraft in mid air and no secondary backup or generators powering the plane (plane is virtually powerless and no comp systems work on board), would the ATC still be able to detect the aircraft with accuracy and if yes how is it done ? Are there any conditions that it has to be flying in an area which is monitored or any basic stuff which HAS to be working for ATC to detect ?&lt;/p&gt;&#xA;" OwnerUserId="2858" LastEditorUserId="64" LastEditDate="2015-01-13T16:32:31.207" LastActivityDate="2015-01-13T16:32:31.207" Title="Can a commercial aircraft be detected by ATC's / Radar systems if all its engines fail?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7729" PostTypeId="2" ParentId="7728" CreationDate="2014-07-16T12:24:28.307" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Radar&quot; rel=&quot;nofollow&quot;&gt;RAdio Detection And Ranging&lt;/a&gt; do not require active participation from the airplane, so ATC will still see it. However, ATC will not know of the plane's condition and will likely not be able to communicate with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pretty much, if the craft is made out of metal and is reasonably high in the air, ATC will see it. Most non-metals will show up on radar as well, such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Larry_Walters&quot; rel=&quot;nofollow&quot;&gt;this guy&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="2171" LastEditDate="2014-07-16T15:26:49.097" LastActivityDate="2014-07-16T15:26:49.097" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7730" PostTypeId="2" ParentId="7728" CreationDate="2014-07-16T12:30:17.487" Score="3" Body="&lt;p&gt;Primary radar (send out radio pulse and interpret reflections) was designed for this (detect uncooperative enemy aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more complete explanation of this system can be found on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/115/what-is-the-range-and-accuracy-of-atc-radar-systems?rq=1&quot;&gt;answers of this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, when all engines fail the backup is a Ram Air Turbine which gets deployed automatically and provides enough power for critical systems including controlling the craft, radio and transponder. Having every backup fail is extremely unlikely.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-07-16T12:30:17.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7731" PostTypeId="2" ParentId="7728" CreationDate="2014-07-16T13:22:18.033" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;In an event of failure of all engines of a commercial aircraft in mid air ...&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That would be a very rare event. In the modern cases where this has happened within an ATC area, it has not prevented location of the aircraft so far as I know.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;... and no secondary backup or generators powering the plane&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even a two-engined airliner has an Auxiliary Power Unit (APU) and a Ram-Air Turbine(RAT). I believe they also typically have 10-15 minutes &lt;a href=&quot;http://www.erieaviation.com/EPSU.htm&quot;&gt;battery power&lt;/a&gt; for critical systems. I don't know if any airliner has ever lost all generators other than in cases where the aircraft was destroyed in flight (e.g. PanAm 103).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;would the ATC still be able to detect the aircraft with accuracy&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If an aircraft's transponder and secondary-radar are not operating, ATC would rely on primary radar, which is less accurate, particularly for altitude. They would also ask the pilots for their position over VHF radio and ask other aircraft in the area to locate the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Example: &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_9&quot;&gt;British Airways Flight 9&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;All four engines flamed out due to ingestion of volcanic ash. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Despite the crew &quot;squawking&quot; the emergency transponder setting of 7700, the aeroplane could not be located by Air Traffic Control on their radar screens.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilot communicated with ATC over VHF radio and later restarted the engines.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The engines had enough electrical power to restart because &lt;strong&gt;one generator and the onboard batteries were still operating&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Example &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;Air Canada Flight 143&lt;/a&gt; (the &quot;Gimli Glider&quot;)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This 767 ran out of fuel mid-air and all engines stopped. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 767 was one of the first airliners to include an Electronic Flight Instrument System (EFIS), which operated on the electricity generated by the aircraft's jet engines. With both engines stopped, the system went dead, leaving only a few basic &lt;strong&gt;battery-powered&lt;/strong&gt; emergency flight instruments. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilot communicated with ATC Winnipeg and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First Officer Maurice Quintal began to calculate whether they could reach Winnipeg. He used the altitude from one of the mechanical backup instruments, while the distance traveled was supplied by the &lt;strong&gt;air traffic controllers in Winnipeg, measuring the distance the aircraft's echo moved on their radar screens&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, If the aircraft with all engines out is in radar range and ATC are attentive, they can track the aircraft's location.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-16T15:14:04.270" LastActivityDate="2014-07-16T15:14:04.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7732" PostTypeId="2" ParentId="7711" CreationDate="2014-07-16T15:04:19.357" Score="26" Body="&lt;p&gt;Yes, all aircraft have a glide ratio.  On many of the higher-performance fighters, it's 1:1 at best (1 foot altitude traded for one foot forward gliding).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the newer fighter aircraft are intentionally unstable.  They aren't really flown by the pilot; they're flown by a Flight Control Computer System (FLCCS) which depends on electrical and hydraulic power; the pilot tells the FLCCS what they want to do and the FLCCS uses electrical signals and hydraulics to move the flight controls.  Electricity and hydraulic power are provided by generators and pumps on a gearbox driven by the engine.  Ergo, engine-out (especially on a single-engine bird) means they can lose the FLCCS which means they are, effectively, giant &quot;lawn darts.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I spent multiple years as a Crew Chief on F-16's with Uncle Sam's Air Force.  As a single-engine plane, we jokingly said that, when the engine went out, it was in &quot;lawn dart mode.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16 does have backup systems.  The aircraft battery will supply power for a couple minutes, depending on what all you're using.  The hydraulic accumulators will provide hydraulic power for a minute or two, assuming you don't get too crazy.  And the Emergency Power Unit (a small, monopropellant turbine in the right strake of the aircraft) will start promptly after losing the engine, providing electricity and hydraulic power for several minutes as necessary (the battery and accumulators keep you under control while it spins up).  Ergo, if you lose the engine, you lose propulsion but you still have electricity and hydraulic power.  So you can still maintain control of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We had more than one occasion, in my time, where we had an F-16 engine conk out (we were playing with brand spankin' new Block 50s with a new model of engine) and the pilot managed to glide the plane in without injury or damage to the aircraft.  They were near the base when it happened, the EPU fired (so they were able to maintain control of the aircraft), the glide ratio was sufficient to reach the runway and the tailhook (yes, Air Force birds have 'em) caught the cable and stopped them safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the short answer is yes, modern fighter planes can glide.  Different planes have different ratios, some of them little better than a rock thrown at altitude.  And, even if they're designed to be inherently unstable, they have backup systems such that the pilot can maintain control in an engine-out situation.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="2859" LastEditDate="2015-04-17T19:59:01.430" LastActivityDate="2015-04-17T19:59:01.430" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7733" PostTypeId="2" ParentId="3425" CreationDate="2014-07-16T16:38:22.393" Score="1" Body="&lt;p&gt;I recall hearing about F-15s making ballistic suborbital flights, by simply getting up enough of a head of steam to coast through near-space. I don't think they actually went into &quot;space&quot; (100 km altitude) and they certainly didn't make orbit. Does anyone else recall the specifics on this? I can find some references online to using F-15s to test launch ASAT missiles, but my recollection was that the whole aircraft actually went high enough to get well above maximum cruising altitude.&lt;/p&gt;&#xA;" OwnerUserId="1078" LastActivityDate="2014-07-16T16:38:22.393" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7734" PostTypeId="1" AcceptedAnswerId="7737" CreationDate="2014-07-16T17:34:53.290" Score="9" ViewCount="4726" Body="&lt;p&gt;Let's say I have an already-built airplane with known basic characteristics like weight, wing span and wing surface, and I can measure the time of all possible manoeuvres at different speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I calculate the &lt;a href=&quot;https://en.wikipedia.org/wiki/Roll_moment&quot; rel=&quot;noreferrer&quot;&gt;roll moment&lt;/a&gt; of an aileron in its maximal deflection? The precision of hundreds of [kg*m] is sufficient.&lt;/p&gt;&#xA;" OwnerUserId="2864" LastEditorUserId="849" LastEditDate="2014-07-20T18:56:55.813" LastActivityDate="2020-04-23T09:37:17.923" Title="How can I calculate the rolling moment of an aileron for a given plane based on its performance?" Tags="&lt;aerodynamics&gt;&lt;ailerons&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7735" PostTypeId="2" ParentId="1339" CreationDate="2014-07-16T18:10:07.600" Score="6" Body="&lt;p&gt;It depends on your state laws for what is permitted for filing a Mechanics Lien. For example in California you cannot hold the persons property. In Texas, you can both hold the property and then sell it at auction if they don't pay up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you would like to file a Mechanics lien, the cost is $45 dollars and can be processed through www.planefax.com which operates directly within the FAA's documents room in Oklahoma City. Plane Fax can also further advise if you have a valid lien or not. The process is called perfecting a lien.  &lt;/p&gt;&#xA;" OwnerUserId="2865" LastActivityDate="2014-07-16T18:10:07.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7736" PostTypeId="1" AcceptedAnswerId="7738" CreationDate="2014-07-16T19:40:22.537" Score="24" ViewCount="7123" Body="&lt;p&gt;I was watching a &lt;a href=&quot;http://www.youtube.com/watch?v=eWtPA8v-xeQ&quot;&gt;video&lt;/a&gt; of the first A350 flight. At &lt;a href=&quot;http://www.youtube.com/watch?v=eWtPA8v-xeQ#t=35&quot;&gt;0:35&lt;/a&gt; one of the pilots appears to be wearing a helmet and what looks like a parachute. Is that true? Do pilots on maiden flights wear such a kit, so that in case of an emergency they can evacuate the airplane?&lt;/p&gt;&#xA;" OwnerUserId="1534" LastEditorUserId="7532" LastEditDate="2016-07-09T19:46:54.033" LastActivityDate="2016-07-09T19:46:54.033" Title="Do test pilots on commercial aircraft wear a parachute?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;parachute&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7737" PostTypeId="2" ParentId="7734" CreationDate="2014-07-16T21:09:40.627" Score="11" Body="&lt;p&gt;If you know the rolling speed at a given flight speed, you can calculate the aileron effectiveness and use that to calculate the forces. The final rolling speed is reached when roll damping and the aileron-induced rolling moment reach an equilibrium: &lt;span class=&quot;math-container&quot;&gt;$$c_{l\xi} \cdot \frac{\xi_l - \xi_r}{2} = -c_{lp} \cdot \frac{\omega_x \cdot b}{2\cdot v_\infty} =  -c_{lp} \cdot p$$&lt;/span&gt;&#xA;Thus, your aileron effectiveness is &lt;span class=&quot;math-container&quot;&gt;$$c_{l\xi} = -c_{lp}\cdot\frac{\omega_x \cdot b}{v_\infty\cdot(\xi_l - \xi_r)}$$&lt;/span&gt;&#xA;The roll damping term is for unswept wings &lt;span class=&quot;math-container&quot;&gt;$$c_{lp} = -\frac{1}{4} \cdot \frac{\pi \cdot AR}{\sqrt{\frac{AR^2}{4}+4}+2}$$&lt;/span&gt;&#xA;and the moment per aileron now is &lt;span class=&quot;math-container&quot;&gt;$$M = c_{l\xi} \cdot \xi \cdot S_{ref} \cdot b \cdot q_\infty$$&lt;/span&gt;&#xA;Calculate the moment for each aileron separately; normally the left and right deflection angles are not exact opposites, which helps to reduce stick forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you only need an approximation, maybe do it like this:&lt;P&gt;&#xA;You first need to have all dimensions and the deflection angles. I expect you don't have lift polars of the wing section, so you need to approximate the lift increase due to aileron deflection with general formulas. This is &lt;span class=&quot;math-container&quot;&gt;$$c_{l\xi} = c_{l\alpha} \cdot \sqrt{\lambda} \cdot \frac{S_{aileron}}{S_{ref}} \cdot \frac{y_{aileron}}{b}$$&lt;/span&gt;&#xA;and the moment per aileron now is &lt;span class=&quot;math-container&quot;&gt;$$M = c_{l\xi} \cdot \xi \cdot S_{ref} \cdot b \cdot q_\infty = c_{l\alpha} \cdot \sqrt{\lambda} \cdot \xi \cdot S_{aileron} \cdot y_{aileron} \cdot q_\infty$$&lt;/span&gt;&#xA;Nomenclature:&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$p \:\:\:\:\:\:\:\:$&lt;/span&gt;  dimensionless rolling speed (= &lt;span class=&quot;math-container&quot;&gt;$\omega_x\cdot\frac{b}{2\cdot v_\infty}$&lt;/span&gt;). &lt;span class=&quot;math-container&quot;&gt;$\omega_x$&lt;/span&gt; is the roll rate in radians per second.&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$b \:\:\:\:\:\:\:\:\;$&lt;/span&gt;  wing span&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_{l\xi} \:\:\:\:\:\:\;$&lt;/span&gt;  aileron lift increase with deflection angles &lt;span class=&quot;math-container&quot;&gt;$\xi$&lt;/span&gt;&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$\xi_{l,r} \:\:\:\:\:\:$&lt;/span&gt;  left and right aileron deflection angles (in radians)&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_{lp} \:\:\:\:\:\:\:$&lt;/span&gt;  roll damping&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_{l\alpha} \:\:\:\:\:\;$&lt;/span&gt; the wing's lift coefficient gradient over angle of attack. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;this answer&lt;/a&gt; on how to calculate it.&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$\pi \:\:\:\:\:\:\:\:$&lt;/span&gt;  3.14159&lt;span class=&quot;math-container&quot;&gt;$\dots$&lt;/span&gt;&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$AR \:\:\:\:\:$&lt;/span&gt;  aspect ratio of the wing&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$\lambda \:\:\:\:\:\:\:\:$&lt;/span&gt;  relative aileron chord&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$S_{aileron} \:$&lt;/span&gt;  Surface area of the aileron-equipped part of the wing &lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$S_{ref} \:\:\:\:\:$&lt;/span&gt;  Reference area (normally the wings's area)&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$y_{aileron} \:$&lt;/span&gt;  spanwise center of the aileron-equipped part of the wing&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$v_\infty \:\:\:\:\:\:$&lt;/span&gt; true flight speed&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$q_\infty \:\:\:\:\:\:$&lt;/span&gt; dynamic pressure&lt;br&gt;&#xA;&lt;P&gt;&#xA;Depending on the relative chord length of the aileron, this formula is good for maximum deflections of 20° of a 20% chord aileron or 15° deflection of a 30% chord aileron. Remember: This is a rough estimate for straight wings.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-23T09:37:17.923" LastActivityDate="2020-04-23T09:37:17.923" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7738" PostTypeId="2" ParentId="7736" CreationDate="2014-07-16T22:01:02.437" Score="27" Body="&lt;p&gt;To the best of my knowledge, all commercial aircraft being tested have their pilots take on parachutes and hi-vis clothing in addition to creating a possible means of egress on all important flights, such as the first flight and high-speed tests. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since getting the cabin doors open is practically difficult, the solution I think most producers use is to built a chute down the front cargo entrance which can open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bombardier produced a &lt;a href=&quot;https://www.youtube.com/watch?v=lWIOQuQBKFM&quot; rel=&quot;noreferrer&quot;&gt;pretty extensive film&lt;/a&gt; for their new CSeries.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the solution employed on the Concorde:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1MZVQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1MZVQ.jpg&quot; alt=&quot;Concorde escape hatch&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="64" LastEditDate="2014-07-16T22:43:35.470" LastActivityDate="2014-07-16T22:43:35.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7739" PostTypeId="1" CreationDate="2014-07-17T03:36:08.150" Score="2" ViewCount="554" Body="&lt;p&gt;The flight data recorder is one important piece of information in the event of a crash. Can this information not be transmitted or relayed to the ATC's while the flight is air borne so that they don't have to wait to recover the data recorder after a crash ? I mean to say that periodically the data can be sent back to a ground controller when the signal strength is high and it can be logged. Please let me know if there are any limitations to the amount of data that an air borne flight can relay back to the controller.&lt;/p&gt;&#xA;" OwnerUserId="2862" LastActivityDate="2014-07-17T10:46:55.457" Title="Can airplanes transmit/relay flight data to ATC's periodically while in flight?" Tags="&lt;air-traffic-control&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2014-07-17T11:02:24.307" ContentLicense="CC BY-SA 3.0" />
  <row Id="7740" PostTypeId="2" ParentId="7739" CreationDate="2014-07-17T04:26:00.693" Score="1" Body="&lt;p&gt;No, there's no data relayed like this to ATC. All ATC really gets is the filed flight plan, and then the transponder data. ATC just cares about organizing all the traffic in the skies, and making sure it is safe, orderly, and expeditious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines use a system similar to this to relay maintenance data to the airline from the aircraft, that's how AF447 was found to have something wrong, and how they generally found it's location quickly(I think within 48 hours debris was found from the a/c due to the location info through ACARS(Aircraft Communication and Reporting System)). This system, and it's capabilities are optional and variable depending on what the airline wants to spend. This is why there's so much controversy over the loss of MH370, since they didn't have the full reporting schedule, and a very basic version.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-07-17T04:26:00.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7741" PostTypeId="2" ParentId="7739" CreationDate="2014-07-17T10:18:49.233" Score="0" Body="&lt;h1&gt;Q1 - Position, altitude, speed, heading&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Can airplanes transmit/relay flight data to ATC's periodically while in flight?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;Yes&lt;/h2&gt;&#xA;&lt;h3&gt;1) ADS-B&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Large expanses of Australia and Hudson Bay in Canada, currently without any radar coverage, are now visible on ATC screens after strategic placement of low-cost ADS-B receiving stations&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_02_10/pdfs/AERO_Q2-10_article02.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;2) Inmarsat&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Inmarsat has confirmed it has proposed to ICAO a free global airline tracking service over the Inmarsat network, as part of the anticipated adoption of further aviation safety service measures by the world’s airlines following the loss of flight MH370.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.inmarsat.com/news/inmarsat-provide-free-global-airline-tracking-service/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inmarsat&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Q2 - Engine temperature, flaps setting, control inputs, warnings etc&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;The flight data recorder is one important piece of information in the event of a crash. Can this information not be transmitted or relayed to the ATC's while the flight is air borne&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;No&lt;/h2&gt;&#xA;&lt;p&gt;That would be inappropriate, ATC have no interest in or use for such data. It would be better for the data to be transmitted to the aircraft operator under rules set by a regulatory authority.&lt;/p&gt;&#xA;&lt;h2&gt;Not yet&lt;/h2&gt;&#xA;&lt;p&gt;Live-streaming of flight data has been &lt;a href=&quot;http://www.voanews.com/content/global-airlines-body-recommends-live-streaming-flight-data/1883661.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;proposed&lt;/a&gt; by IATA and has been investigated by the NTSB amongst others.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The U.S. National Transportation Safety Board (NTSB) has said it was studying the possibility of live-streaming data, but Tyler said a broad consensus would be needed between airlines, major manufacturers and regulators.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;It's very important that if we're going to have regulation covering this area, that it's done on a globally consistent basis,'' said Tyler, who joined IATA in 2011 after five years as chief executive of Cathay Pacific Airways.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-07-17T10:46:55.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7742" PostTypeId="2" ParentId="3425" CreationDate="2014-07-17T11:23:15.547" Score="3" Body="&lt;p&gt;It depends what you include in &quot;non-rocket aircraft&quot;.  Wikipedia has a whole article on &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Non-rocket_spacelaunch&quot; rel=&quot;nofollow&quot;&gt;Non-rocket spacelaunch&lt;/a&gt;&quot; which discusses the various options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short version is, there are no current space launch systems which do not use rockets.  The most practical one we know of appears to be &lt;a href=&quot;http://en.wikipedia.org/wiki/Space_gun&quot; rel=&quot;nofollow&quot;&gt;space guns&lt;/a&gt;, which have been successfully &lt;a href=&quot;http://en.wikipedia.org/wiki/Project_HARP&quot; rel=&quot;nofollow&quot;&gt;used for sub-orbital launches&lt;/a&gt; (but are not practical for human spaceflight).&lt;/p&gt;&#xA;" OwnerUserId="414" LastActivityDate="2014-07-17T11:23:15.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7745" PostTypeId="1" AcceptedAnswerId="7748" CreationDate="2014-07-17T16:47:51.263" Score="15" ViewCount="764" Body="&lt;p&gt;I was watching &lt;a href=&quot;https://www.youtube.com/watch?v=lWIOQuQBKFM&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt; about the test flight escape systems on a Bombardier flight. In the video, this machine is shown:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/H5xS3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The yellow box moves up and down in the video. Does it move up and flip the airman over, mashing their feet? Or does it shoot down out of the airplane and create a hole to jump out of? If it's the latter, why are they sitting instead of standing?&lt;/p&gt;&#xA;" OwnerUserId="14" LastEditorUserId="946" LastEditDate="2014-07-17T18:14:56.093" LastActivityDate="2014-07-18T03:26:06.190" Title="How does this test flight escape aparatus work?" Tags="&lt;safety&gt;&lt;flight-testing&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7746" PostTypeId="1" AcceptedAnswerId="7747" CreationDate="2014-07-17T17:40:54.870" Score="21" ViewCount="1043" Body="&lt;p&gt;Apparently &lt;a href=&quot;http://en.wikipedia.org/wiki/MH17&quot;&gt;Malaysia Airlines Flight 17&lt;/a&gt; used a general airway over the east of Ukraine, which currently is &lt;a href=&quot;http://en.wikipedia.org/wiki/2014_pro-Russian_unrest_in_Ukraine&quot;&gt;'in conflict'&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the 'normal' procedures regarding (not) flying over conflict areas? Who is responsible for an up-to-date risk assessment? Who advises? Who makes the (final) decision?&lt;/p&gt;&#xA;" OwnerUserId="1379" LastEditorUserId="65" LastEditDate="2015-03-12T14:47:52.453" LastActivityDate="2015-03-12T14:47:52.453" Title="What are the protocols of flying over conflict areas?" Tags="&lt;safety&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7747" PostTypeId="2" ParentId="7746" CreationDate="2014-07-17T20:01:06.030" Score="10" Body="&lt;p&gt;&lt;strong&gt;This is horrendous Incident, and my heart goes out to the victims Families who lost their loved ones.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FAA filed a special Warning flying over Crimea back in April but apparently not where the airplane went down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The procedure is to avoid flying over (Dead/No fly Zones) which Aviation Authorities are responsible in providing to the Airline companies so they can adjust their flight plans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA Warning over flying over Crimea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DHrX6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FWNrx.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes Flight Path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8uLFn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1732" LastEditorUserId="774" LastEditDate="2014-07-19T02:05:54.840" LastActivityDate="2014-07-19T02:05:54.840" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7748" PostTypeId="2" ParentId="7745" CreationDate="2014-07-18T03:26:06.190" Score="10" Body="&lt;p&gt;Qualification: I am an FAA master parachute rigger and taught sport skydiving for 10 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the comments on the question are correct - the red slide will extend below the airplane and act as a wind buffer so you can clear the fuselage before the wind blast hits you. The yellow part is a cap that would be removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No one would clip a static line to the plane in an evacuation - you want to be well clear of the airplane before opening your own chute. The blue packs are the real thing, I've packed plenty of them. There's a 26-foot round parachute inside. Rough landing but usable by anyone with very little training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How usable this contraption would be is a different question - skydiving is done at about 100 knots, well below the speed of jets. And it also requires a stable aircraft - if that plane loses it's tail and starts to spin no one will be using the escape slide simply because it will be impossible to reach it. The &quot;bail out in the event of emergency&quot; concept is a bit flawed - if the airplane is flying well enough to bail out then you don't need to. There's a very good reason the military spends a fortune on ejection seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note - the Space Shuttle had a crew escape process, but NASA considered landing a shuttle on anything other than a proper runway to be non-survivable.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-18T03:26:06.190" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7749" PostTypeId="2" ParentId="2183" CreationDate="2014-07-18T03:30:32.353" Score="2" Body="&lt;p&gt;The F-16 has an &quot;emergency blow-down&quot; reservoir containing approximately 3,000 psi gaseous nitrogen. Hitting a switch will release this pressurized nitrogen into the hydraulic system dealing with the landing gear. Ergo, hitting that switch will extend the gear, even with the engine off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yeah, the landing gear will still work in the event of a complete power failure. It has backup systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the older A-4 Skyhawk, the landing gear retracted up and forward.  So, in the event of a hydraulic failure, if you could get the gear doors open, the airflow past the aircraft in flight would &quot;drag&quot; the gear down and aft and lock it into position.  I think that's a pretty slick design.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="2859" LastEditDate="2014-09-30T14:43:20.177" LastActivityDate="2014-09-30T14:43:20.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7750" PostTypeId="5" CreationDate="2014-07-18T03:54:10.837" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-18T03:54:10.837" LastActivityDate="2014-07-18T03:54:10.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7751" PostTypeId="4" CreationDate="2014-07-18T03:54:10.837" Score="0" Body="Questions relating to the crash of Malaysia Airlines MH17, in Ukraine on 17th July 2014." OwnerUserId="606" LastEditorUserId="606" LastEditDate="2014-07-18T10:18:07.630" LastActivityDate="2014-07-18T10:18:07.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7752" PostTypeId="1" AcceptedAnswerId="7754" CreationDate="2014-07-18T04:12:07.720" Score="10" ViewCount="4920" Body="&lt;p&gt;I'm working on my instrument rating and wondering if I can practice ILS approaches without an instructor? Using a safety pilot, also not instrument rated, could I call approach stating VFR would like ILS into X. Or do I just call the tower and ask for it there? Or can I only do this with an instructor?&lt;/p&gt;&#xA;" OwnerUserId="2882" LastEditorUserId="572" LastEditDate="2015-02-19T09:06:26.460" LastActivityDate="2015-02-19T09:06:26.460" Title="Can non-instrument rated pilots request practice approaches?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;flight-training&gt;&lt;approach&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7754" PostTypeId="2" ParentId="7752" CreationDate="2014-07-18T06:28:10.867" Score="7" Body="&lt;p&gt;&lt;strong&gt;Sure you can!&lt;/strong&gt; There's nothing wrong with shooting practice approaches if you're not instrument rated (in the US, at least) as long as you don't &lt;em&gt;actually accept&lt;/em&gt; an IFR clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would probably be better off asking approach control for practice approaches rather than tower, if you have approach available to you.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-07-18T06:28:10.867" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7755" PostTypeId="1" AcceptedAnswerId="7767" CreationDate="2014-07-18T06:36:47.440" Score="9" ViewCount="662" Body="&lt;p&gt;My student studied his empennage off and got a 100% on his knowledge test.  Usually, when I endorse students, there's a sentence that goes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have given [name] X hours of instruction on the areas in which he/she was found to be deficient on his/her airman knowledge test.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case, my student wasn't deficient on &lt;em&gt;any&lt;/em&gt; areas of the knowledge test.  &lt;strong&gt;Do I need to make that endorsement?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-04-14T22:45:33.737" Title="What (if any) endorsement do I need to give a student who scored 100% on his knowledge test?" Tags="&lt;logbook-endorsements&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7756" PostTypeId="1" CreationDate="2014-07-18T07:41:06.010" Score="18" ViewCount="941" Body="&lt;p&gt;Who legally owns the Flight Data Recorder after an aircrash?  Who is responsible for retrieving it and/or allowed to retrieve it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And how is it decided who carries out the crash investigation?&lt;/p&gt;&#xA;" OwnerUserId="2883" LastActivityDate="2014-07-18T11:08:45.373" Title="Who legally owns the Flight Data Recorder?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7757" PostTypeId="1" CreationDate="2014-07-18T08:50:36.453" Score="28" ViewCount="19255" Body="&lt;p&gt;Can a civilian aircraft pilot see a missile coming?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &quot;civilian aircraft,&quot; I mean planes that were not equipped with flares that fire when rockets approach  or any similar anti-missile systems.  If these missiles can be detected, can the pilot take any evasive measures?&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="97" LastEditDate="2014-07-19T02:17:15.650" LastActivityDate="2019-11-10T19:37:49.353" Title="Can a civilian aircraft pilot see a missile coming?" Tags="&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;general-aviation&gt;&lt;security&gt;&lt;missiles&gt;" AnswerCount="10" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7758" PostTypeId="2" ParentId="7757" CreationDate="2014-07-18T09:35:30.107" Score="38" Body="&lt;h2&gt;Visual detection&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To take one example, a vehicle-launched ground to air missile system (e.g. the &lt;a href=&quot;http://en.wikipedia.org/wiki/Buk_missile_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;SA-11&lt;/a&gt;) that can reach the cruising altitude of airliners travels at several thousand miles per hour and takes perhaps 30 to 40 seconds from launch to reach its target.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots don't have an especially good view of the ground immediately below and would have a very hard time spotting a missile travelling at those speeds.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Electronic detection&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Civilian airliners are equipped with a collision avoidance system called TCAS. However this relies on radio signals from transponders which are fitted to other aircraft. Naturally, anti-aircraft missiles do not have a transponder and do not advertise their presence. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Missile Countermeasures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Anti-missile systems that are available (&lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_Guardian&quot; rel=&quot;nofollow noreferrer&quot;&gt;example&lt;/a&gt;) are mainly intended to protect against small infra-red seeking man-launched air-defense missiles (MANPADs) rather than larger more sophisticated radar-homing systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even these systems are not fitted to all civilian airliners, probably only to those that operate into airports where there is a current known risk of MANPAD use by terrorists or other armed factions.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Evasion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Civilian aircraft are not designed for high-G evasive maneuvers and in any case, the missile does not have to strike the aircraft, it detonates nearby based on a proximity fuse and the resulting explosion and high velocity fragments will do enough damage to result in the destruction of the target.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1467" LastEditDate="2019-01-08T11:18:42.007" LastActivityDate="2019-01-08T11:18:42.007" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="7759" PostTypeId="2" ParentId="7752" CreationDate="2014-07-18T09:48:06.493" Score="3" Body="&lt;p&gt;Yes, you can request practice approaches under VFR, however you or a safety pilot needs to take over airspace monitoring if you put on an IFR hood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless your question is FAA specific, here are some excerpt from the German AIP.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;562 VFR-PRACTICE APPROACHES &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;562.1 A practice approach may be approved for VFR-flights intending to use an &#xA;  instrument approach procedure for training purposes. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;562.2 When giving heading and altitude recommendations during VFR-practice&lt;br&gt;&#xA;  approaches, it shall be explicitly emphasised that it is a suggestion. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;562.3 If appropriate, altitude information shall be provided to ensure compliance &#xA;  with the minimum safe height. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And also the associated phraseology to request:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A:  REQUEST (type of IFR approach) PRACTICE APPROACH VFR &lt;br&gt;&#xA;  G:   (type of IFR approach) PRACTICE APPROACH VFR APPROVED / NOT APPROVED &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-07-18T09:48:06.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7760" PostTypeId="2" ParentId="7756" CreationDate="2014-07-18T10:39:37.547" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Who legally owns the Flight Data Recorder after an aircrash?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whoever owned it before the crash!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd guess this might be the aircraft owner (e.g. an airline or a leasing company) or an aircraft operator (e.g. an airline).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ownership is less important than the obligations imposed by the relevant regulatory authorities, and probably by international treaties and agreements, effective in the area where the FDR is located after an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For relevant discussion see NTSB &lt;a href=&quot;https://www.ntsb.gov/doclib/manuals/FDR_Handbook.pdf&quot;&gt;FDR Handbook&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;And how is it decided who carries out the crash investigation?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are a complicated set of rules agreed internationally. From memory I think it goes something like this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The government appointed body in whose territory(airspace?) the accident occurred. Or&lt;/li&gt;&#xA;&lt;li&gt;The government appointed body in whose country the aircraft was registered.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;EMSA &lt;a href=&quot;http://www.emsa.europa.eu/retro/Docs/marine_casualties/annex_13.pdf&quot;&gt;state&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.1 The State of Occurrence shall institute an investigation into the circumstances of the accident and be &#xA;  responsible for the conduct of the investigation, but it may delegate the whole or any part of the conducting of such &#xA;  investigation to another State by mutual arrangement and consent. In any event the State of Occurrence shall use &#xA;  every means to facilitate the investigation. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.3 When the location of the accident or the serious incident cannot definitely be established as being in the &#xA;  territory of any State, the State of Registry shall institute and conduct any necessary investigation of the accident or &#xA;  serious incident. However, it may delegate the whole or any part of the investigation to another State by mutual arrangement and consent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aaib.gov.uk/home/index.cfm&quot;&gt;Example 1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The UK Air Accidents Investigation Branch (AAIB) is part of the Department for Transport and is responsible for the investigation of civil aircraft accidents and serious incidents within the UK and its overseas territories.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/&quot;&gt;Example 2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NTSB is an independent Federal agency charged by Congress with investigating every civil aviation accident in the U.S.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Normally an air accident investigation organisation takes the lead role but co-opts experts from the airline, the manufacturer and other air-accident organisations with an interest in the incident or with special expertise. Involvement of interested parties (airline, ATC, manufacturer) obviously has to be handled very carefully to avoid detracting from the independence of the investigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most investigations focus almost exclusively on determining facts and recommending actions to prevent recurrences. They generally are not mainly concerned with assigning blame, that may be the focus of a separate legal inquiry.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-18T11:08:45.373" LastActivityDate="2014-07-18T11:08:45.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7761" PostTypeId="2" ParentId="7757" CreationDate="2014-07-18T11:22:42.437" Score="12" Body="&lt;p&gt;It's possible for a pilot to see a missile's trail provided that the missile is fired from an angle where that trail could be seen out the window, however it's pretty unlikely. Commercial aircraft are not typically fitted with any missile warning or defense systems, so a pilot would have to be looking in the right place at the right time in order to spot it. The pilot would also have to know what he/she is seeing, and recognize the threat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilots of a commercial jet spotted a missile early there are some things they could try:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Climbing: some missiles are shorter range, getting higher could put the aircraft out of range&lt;/li&gt;&#xA;&lt;li&gt;Evasive maneuvers: While commercial jets are not generally thrown around they can pull some Gs. There's a slight chance that some jinking may cause a missile to lose lock. At least a pilot could try and put less critical parts of the airplane closer to the missile. If a missile explodes off the wing-tip it the airplane has a better chance of survival than if the missile explodes next to the fuselage. It's certainly worth a try as many of the older missiles out there aren't particularly reliable&lt;/li&gt;&#xA;&lt;li&gt;Reduce infrared signature: Although there are plenty of radar guided missiles out there these are generally the province of militaries, or better supplied revolutionary groups, so the most likely scenario for an airliner being attacked is by hand-held infrared guided missiles. There are a lot of old and less sophisticated SAMs out there, which are easier to fox. A pilot faces with one of these could turn the aircraft so the wings block the engines' heat signature from the missile, and possibly reduce engine power. An aircraft at cruising altitude would not be at risk from one of these though, so this tactic would not be of any help&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Realistically a pilot of a commercial jet is unlikely to spot a missile before it is far too late to do anything about it, if he/she spots it at all. So while it is within the realm of possibility that an alert (and lucky) pilot could evade or mitigate the damage from a missile, it's a long shot at best. A commercial jet targeted by a modern, radar guided missile designed to destroy fast, nimble targets is unlikely to survive. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-07-18T11:22:42.437" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7762" PostTypeId="1" CreationDate="2014-07-18T15:44:00.620" Score="8" ViewCount="911" Body="&lt;p&gt;Can a passenger who has booked a flight wants to learn about the filed flight plan of their flight, prior to boarding it? I'm aware that the flight plan can change, or an aircraft can deviate from it, but still desire a rough map. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware of websites like Flightaware.com, but I think they only start tracking after departure? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in the future, I'd want to see beforehand whether the aircrew decides to fly near a no-fly zone or dangerous area. &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="39" LastEditDate="2014-07-18T19:26:37.413" LastActivityDate="2014-07-18T19:26:37.413" Title="Can confirmed passengers preview or request flight plans before the flight?" Tags="&lt;passenger&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7763" PostTypeId="2" ParentId="7757" CreationDate="2014-07-18T15:56:20.100" Score="14" Body="&lt;p&gt;&lt;a href=&quot;http://www.cnn.com/2014/07/18/opinion/palmer-pilots-missiles/index.html?hpt=hp_t3&quot;&gt;This recent article on CNN&lt;/a&gt; is very informative and covers most of what you're discussing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In brief, commercial aircraft don't have any reasonable means to detect an incoming missile, which is likely to be travelling at supersonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if they could detect it, commercial aircraft are already flying near their limits with respect to altitude, max-speed and min-speed.  So there is very little they could do to evade a missile. (Perhaps counter-intuitively, aggressive maneuvering will actually make it easier for the missile to hit them.  Maneuvering will cost speed and/or altitude, and the missile can easily outperform a commercial airliner in terms of turn rates)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equipping commercial aircraft with anti-missile measures is technically difficult, very expensive, and ultimately of dubious value.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="946" LastEditDate="2014-07-18T23:49:53.597" LastActivityDate="2014-07-18T23:49:53.597" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7764" PostTypeId="1" CreationDate="2014-07-18T15:56:39.540" Score="4" ViewCount="1182" Body="&lt;p&gt;Say that after a passenger learns of or views the flight plan, she opposes it (eg due to safety).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;She could just refuse to board the flight and forfeit her ticket and costs, but are there less costly and dire and radical options? Despite being only a passenger, could she explain to the flight crew (plausibly via the cabin crew?) her reasons and thus request the reconsideration of the flight route? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Supplementary:&lt;/strong&gt; I elucidate that I do NOT mean for her to compel or impress a specific route (replete with all the waypoints, VORs, etc...) upon the flight crew, but only a general concern for avoidance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an instantiation, if I were a passenger and had apprehended my flight to overfly Ukraine, even outside of the no-fly zone, then I'd remonstrate against it, in favor of a more northern one that would substantively avoid Ukraine.&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="504" LastEditDate="2014-07-20T18:56:30.360" LastActivityDate="2014-07-22T20:15:26.443" Title="What can a passenger do if (s)he objects to the flight route?" Tags="&lt;passenger&gt;&lt;airliner&gt;&lt;flight-plans&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7765" PostTypeId="2" ParentId="7764" CreationDate="2014-07-18T16:13:37.660" Score="15" Body="&lt;p&gt;The passenger can in all likelihood do nothing that is going to change the route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you point out, there is always the option to not board. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On long range flights like this, the routing will (depending on winds aloft and other conditions) almost certainly require a fairly direct route to insure that additional fuel stops are not needed. In cases where routes go over warzones or other dangerous areas, they are often rerouted, but in the case of Ukraine the conflict has until now been isolated and military in nature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either you trust the flight crew to &lt;em&gt;also&lt;/em&gt; be aware of these risks, or you don't. Get on board, or not. I'm sure you could raise the issue with a gate agent, and if you made enough noise or escalated it, you might be able to get a refund (&lt;em&gt;note: I have no idea&lt;/em&gt;). However, you also might be perceived as the source of the risk and detained!&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-07-18T16:13:37.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7766" PostTypeId="2" ParentId="7762" CreationDate="2014-07-18T16:16:52.463" Score="10" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, and you don't even have to be a confirmed passenger (that would be kind of weird). There are probably several sources for this, but &lt;a href=&quot;http://flightaware.com/live/flight/UAL1/history/20140719/1415Z/KIAH/RJAA&quot; rel=&quot;noreferrer&quot;&gt;FlightAware includes filed route information for upcoming flights&lt;/a&gt;. Note that this link won't work very well in a week, since it's datestamped to the future. However, they show the route on the map, and also print out the current planned route:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h1&gt;UAL1&lt;/h1&gt;&#xA;&lt;p&gt;KIAH STYCK1 DOLEY ADM J21 IRW HYS LBF RAP GGW YEA YEG 5600N 12000W BINGA NCA11 COHIL WUXAN 6000N 16000W 5900N 17000W 5700N 18000E ONEIL R580 OPAKE R580 OLCOT R580 OATIS Y802 ARMOR Y810 KETAR Y811 VEPOX Y811 MELON RJAA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1MOTr.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-07-18T16:31:56.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7767" PostTypeId="2" ParentId="7755" CreationDate="2014-07-18T17:00:57.140" Score="5" Body="&lt;p&gt;If we're talking about FAA regs I'm not aware of any endorsement required if your student passes the test with a perfect score (they need an endorsement to take the test - &lt;code&gt;I have given the instruction required by...&lt;/code&gt;, and they need an endorsement like the one in your question if they fail or don't manage a perfect score).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The endorsement above is intended for use when you need to endorse someone who failed to re-take the exam (similar to what's done if they fail a checkride), or when there's stuff to review from the knowledge test (My instructor combined it in my Checkride endorsement - &lt;code&gt;And has demonstrated satisfactory knowledge of the areas found deficient on the knowledge test&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it is probably a good idea to cover anything the student missed on the exam or doesn't feel 100% confident on, and to log that training - in this case if you do additional ground work you would just log it as you normally do...&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-07-18T19:41:11.290" LastActivityDate="2014-07-18T19:41:11.290" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7768" PostTypeId="1" AcceptedAnswerId="7770" CreationDate="2014-07-18T17:28:15.313" Score="13" ViewCount="3822" Body="&lt;p&gt;Why is it that commercial passenger aircraft that fly through dangerous areas don't carry some sort of electronic counter measure to defend themselves from missiles?  Between terrorism and the various war zones dotting the globe, it seems like it would be prudent for airliners to have them.  At least for aircraft that are flying in places that are possibly dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been thinking that it's probably a lot of expense and weight for something that isn't terribly likely to happen, but I wondered if there might be more to the answer or if, at very least, someone could add some details to my assumption.  A good cost/benefit analysis would be appreciated if anyone is familiar with the cost of operating such a system.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="97" LastEditDate="2014-07-19T02:21:43.600" LastActivityDate="2014-07-21T18:36:06.000" Title="Why don't airliners carry radar jamming technology or missile counter measures?" Tags="&lt;airliner&gt;&lt;security&gt;&lt;missiles&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7769" PostTypeId="2" ParentId="7768" CreationDate="2014-07-18T17:39:43.083" Score="3" Body="&lt;p&gt;You answered your question already. Weight limitations, cost of installation and maintenance and likelihood of the system really being required or used - it is just not worth it for carriers.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-07-18T17:39:43.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7770" PostTypeId="2" ParentId="7768" CreationDate="2014-07-18T18:34:40.510" Score="20" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al#Flight_security_measures&quot;&gt;El Al&lt;/a&gt; (and other Israeli) aircraft are equipped with &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_Guard&quot;&gt;infra-red countermeasures&lt;/a&gt; since fire at Arkira B757 in Mombasa in 2002. Infra-red counter-measures are relatively simple (it has a small radar to detect missiles and if one is detected, dispenses burning decoys), so it can be mounted on almost any aircraft. The system however poses additional fire risk (the flares have to burn very hot and the system has to be able to ignite them), so it is only used in areas where risk of terrorist attack is high. Switzerland (and possibly other countries) even prohibit it on their territory. Apparently laser-based system is in development to resolve the fire issue, but it will still only work against IR-guided missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for radar guided missiles like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Buk_missile_system&quot;&gt;Buk&lt;/a&gt; system probably involved in this incident there only seem to be three defences:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Hit the tracking radar with your own missile (like &lt;a href=&quot;http://en.wikipedia.org/wiki/AGM-88_HARM&quot;&gt;AGM-88 HARM&lt;/a&gt;) before they hit you. Fighter aircraft is obviously needed to carry it, though most fighter types could be used as they only need radar detector and suitable hardpoints.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Generate sufficiently intense microwave signal that it overdrives the detector in the missile head and effectively blinds it. This is heavy, expensive and requires power (not outside the range of common aircraft generators, but the increased fuel burn would probably be noticeable), so even most fighters don't have it. Instead the system (like &lt;a href=&quot;https://en.wikipedia.org/wiki/AN/ALQ-99&quot;&gt;AN/ALQ-99&lt;/a&gt;) is mounted on special-purpose aircraft like &lt;a href=&quot;http://en.wikipedia.org/wiki/EF-111&quot;&gt;EF-111A Raven&lt;/a&gt; that gets included in attack group trying to penetrate enemy territory with heavy air defences.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Minimizing radar cross-section, ie. stealth. That requires completely different designs that are aerodynamically less efficient, because the funny shapes are necessary part of being stealth and that are not trackable by ATC surveillance radars.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Obviously the first is out of question for airliners - carrying any weapons or munitions of war on civil airliners is prohibited by &lt;a href=&quot;http://www.icao.int/publications/pages/doc7300.aspx&quot;&gt;Convention of International Civil Aviation&lt;/a&gt; article 35.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the second would be technically possible (&lt;a href=&quot;http://en.wikipedia.org/wiki/E-4B&quot;&gt;E-4B&lt;/a&gt;, an airborne command centre, and &lt;a href=&quot;http://en.wikipedia.org/wiki/VC-25&quot;&gt;VC-25&lt;/a&gt;, the Air Force One, are modified Boeing 747s and both have counter-measures against both IR-guided and radar-guided missiles), those modifications would be a heavy, expensive and complex protection against something that &lt;a href=&quot;http://www.npr.org/blogs/parallels/2014/07/17/332318322/a-brief-history-of-civilian-planes-that-have-been-shot-down&quot;&gt;has only happened a few times&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the third would have too many disadvantages. It would hide the aircraft from ATC surveillance radars that have averted many more accidents than were caused by missiles and it would require new, less efficient designs that would be massively expensive. Just few month ago we wanted MH-370 to &lt;em&gt;be&lt;/em&gt; seen by radars. We can't have both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Staying away from the war zones is a safer option anyway and is normally possible. In this case likely explanation why MH-17 didn't is that the Ukrainian authorities were not aware that the rebels have this air defence system, assumed they only have a lighter-weight one (those are often usable to about 20000'; the military aircraft shot down on previous days were lower) and only closed the airspace up to FL320 rather than completely.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-07-21T18:36:06.000" LastActivityDate="2014-07-21T18:36:06.000" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7773" PostTypeId="2" ParentId="3439" CreationDate="2014-07-19T02:54:40.147" Score="4" Body="&lt;p&gt;I just found an AIC (&lt;a href=&quot;http://www.ead.eurocontrol.int/eadbasic/pamslight-9CC39AE5A176FDBE6621F1F7DB628B53/7FE5QZZF3FXUS/EN/AIC/Y/009-2014/EG_Circ_2014_Y_009_en_2014-02-20.pdf&quot; rel=&quot;nofollow&quot;&gt;POLICY FOR THE APPLICATION OF CALLSIGNS TO HELICOPTER EMERGENCY MEDICAL SERVICE FLIGHTS&lt;/a&gt;) of relevance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HEMS flights are prioritised by ATC:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Flight Category is a priority status allocated to a flight by the Civil Aviation Authority (CAA) designed for use with tactical&#xA;  handling by ATC. There are 7 categories of flight as defined in MATS Pt 1 page 1-31. They are: Category A-E; Normal flights and&#xA;  Category Z. The flight categories relevant to HEMS operations are:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Flight Category A - the highest category of flight, applies to all HEMS flights, as defined at paragraph 2.1;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Flight Category E - is authorised for use by an aircraft positioning for the purpose of conducting HEMS duties, eg&#xA;  returning to base after delivering a casualty to hospital. It is afforded priority over normal flights;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Flight Category Z - is authorised for flights involving the training of crews for HEMS operations.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-07-19T02:54:40.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7774" PostTypeId="1" CreationDate="2014-07-19T03:08:27.727" Score="7" ViewCount="622" Body="&lt;p&gt;I just noticed an interesting AIC: &lt;em&gt;NOTIFICATION OF GPS JAMMING EXERCISE – HEBRIDES RANGES DURING PERIOD 21 JULY - 1 AUGUST 2014&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PDF available on &lt;a href=&quot;http://www.ead.eurocontrol.int/eadbasic/pamslight-9CC39AE5A176FDBE6621F1F7DB628B53/7FE5QZZF3FXUS/EN/AIC/P/065-2014/EG_Circ_2014_P_065_en_2014-06-12.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurocontrol (official)&lt;/a&gt; or &lt;a href=&quot;http://www.scribd.com/doc/234593596/AERONAUTICAL-INFORMATION-CIRCULAR-P-65-2014-UNITED-KINGDOM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scribd (mirror)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Ministry of Defence is planning a GPS jamming exercise:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Jamming will occur across the 24 MHz bands centred around 1227.60 MHz and 1575.42 MHz. A Falcon 20 aircraft will be equipped with 2 high power jamming pods (1kw), one for each&#xA;  GPS frequency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What effect would this have on a plane entering the jammed airspace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/7813/can-a-gps-signal-sent-to-a-plane-be-spoofed&quot;&gt;Can a GPS signal sent to a plane be spoofed?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-07-22T00:02:45.547" Title="What effect would an air-to-air GPS jamming system have?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;&lt;security&gt;&lt;gnss&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7777" PostTypeId="2" ParentId="7768" CreationDate="2014-07-19T06:32:04.753" Score="21" Body="&lt;p&gt;Surface-to-air missile attacks on airliners at cruising altitude are vanishingly rare: there have only been three known attacks in the past half-century (MH-17, IR-655, and probably S7-1812).  Any protection system needs to take that into account -- any safety system needs to be justified in terms of cost, weight, and safety -- it needs to save more lives than it costs.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Direct jamming.  Suppose you stick an &lt;a href=&quot;https://en.wikipedia.org/wiki/AN/ALQ-99&quot;&gt;AN/ALQ-99 jamming pod&lt;/a&gt; on the airplane.  That's 6000 extra pounds, a good deal of drag, and a bunch of parts that can break off, catch fire, or otherwise be a hazard.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Active countermeasures.  Stick an &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-88_HARM&quot;&gt;AGM-88 HARM missile&lt;/a&gt; on the plane.  Now, your anti-radar missile isn't much faster than the radar-guided missile trying to shoot you down, so for reasonable safety, you need to launch as soon as you get painted by the tracking radar.  What do you suppose the odds are that a twitchy co-pilot acting as ECM/weapons officer is going to launch against an innocent control tower?  How many weather radars are you willing to destroy to save that one airplane every 20 years?  Are you sure that missile will never malfunction on the launching rack and destroy the airplane?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stealth.  Hiding from radar-guided missiles means you're also hiding from traffic-control radar.  How often are crashes prevented by that radar?  I bet it's more than one every twenty years.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The benefit is roughly one less airplane crash every 20 years.  That means the cost, both in terms of money and in terms of risk, needs to be very, very low.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-07-19T06:32:04.753" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7778" PostTypeId="2" ParentId="7774" CreationDate="2014-07-19T07:03:02.997" Score="6" Body="&lt;p&gt;Jamming GPS means that the GPS receiver is unable to lock-on to the signal from any satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably, pilots of small aircraft would have to revert to more traditional forms of navigation - assuming they have a GPS based navigational instrument or two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots of airliners would presumably see alerts and (as with most smaller aircraft?) their flight displays would include non GPS sources such as gyrocompasses or magnetic compasses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine redundant systems would include other sources of position information such as reception of &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow&quot;&gt;radio-based omnidirectional navigation beacons&lt;/a&gt;, inertial navigation systems and looking out the window.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="97" LastEditDate="2014-07-22T00:02:45.547" LastActivityDate="2014-07-22T00:02:45.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7779" PostTypeId="2" ParentId="7757" CreationDate="2014-07-19T08:32:39.623" Score="1" Body="&lt;p&gt;RWR Radar warning receivers can help detect if the aircraft is being tracked by a targeting radar and if the incoming missile is an active type, it is possible for RWR to detect this as well. There are counters to this such as frequency hopping and spread spectrum radar, so it is also possible that the targeted aircraft remains unaware. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft can be fitted with launch plume detectors which sense the IR or UV from a missile, either at launch or during flight, these again are not foolproof.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to jamming - consider the home on jam (HOJ) technologies, where the incoming missile uses the jamming emitter as it's target, making the jamming vehicle vulnerable to attack, several missile systems employ HOJ, such as the A-88 HARM and the AIM-120 AMRAM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether any aircraft has the ability to evade a missile depends on many variables, but mainly boils down to how much energy the incoming missile has i.e. burn time on the propellant or kinetic energy if the propellant is exhausted and the same for the aircraft, hight, speed, thrust and the manoeuvring envelops for the two, which means radius of turn, amount of G, sustained G. Civil airliners don't really have high G capabilities, if the pilot were to spot the missile early and the distance was great, turning and running in a shallow dive with a max G turn just before impact might, if the missile has very low energy, work, but these systems have a very good probability of kill against large targets with relatively poor manoeuvrability.  &lt;/p&gt;&#xA;" OwnerUserId="2902" LastActivityDate="2014-07-19T08:32:39.623" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7780" PostTypeId="2" ParentId="7757" CreationDate="2014-07-19T08:43:01.733" Score="5" Body="&lt;p&gt;I am a weapon system designer/systems engineer and scientist by background.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know civil airlines all have identification transponders. Normal radar surveillance would be able to access the identity of the aircraft and then decide what to do. This is of course fine for air traffic monitoring systems unlikely to be in the possession of a small militia. As other's have said the weapon system itself will neither respond nor interrogate a target plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These days there is no honour code to force people to tell the truth or stand in the open when fighting a war. Even if a plane were entering a threat area sending out a clear signal saying I am a civil airliner, the force under threat would be foolish to believe it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary means of safety is for air traffic control authorities to advise about the location of war areas and for airline operators to protect their planes and passengers by avoiding them. Whatever the root cause of the conflict in Ukraine, it was for Malaysian Airlines to avoid the area just in case one side had active anti aircraft missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surface to Air Missiles are a very desirable weapon famously used to retain (defend) captured territory - US missiles were used by Israel in the six-day war, now it seems the Ethnic Russian forces in eastern Ukraine are using Russian air defence weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I won't be flying Malaysian any time soon.&lt;/p&gt;&#xA;" OwnerUserId="2903" LastActivityDate="2014-07-19T08:43:01.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7781" PostTypeId="1" AcceptedAnswerId="7782" CreationDate="2014-07-19T13:45:58.910" Score="8" ViewCount="1858" Body="&lt;p&gt;I was looking at the path of the MH-17 flight that crashed in the Ukraine on &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;noreferrer&quot;&gt;FlightRadar24&lt;/a&gt; and noticed it was flying at FL310 (31,000ft), then because of the Ukrainian NOTAM which went up to FL320 (32,000ft) and below, it then ascended to FL330.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why wouldn't it be flying at FL330 already from the start? Doesn't a higher altitude mean less air resistance (because the air is thinner) and therefore better fuel efficiency?&lt;/p&gt;&#xA;" OwnerUserId="2907" LastEditorUserId="30128" LastEditDate="2019-03-27T14:28:35.100" LastActivityDate="2019-03-27T21:03:46.613" Title="Why wasn't MH-17 flying at 33,000ft before it entered Ukrainian airspace?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;fuel&gt;&lt;mh17-accident&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7782" PostTypeId="2" ParentId="7781" CreationDate="2014-07-19T15:54:09.097" Score="22" Body="&lt;p&gt;This is normal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 777 on the AMS-KUL route cannot climb to FL330 right after takeoff - this would only be possible maybe 3-5 hours into the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners fly as high as the available thrust (and ATC) allows, because the thinner air allows to fly at a higher lift coefficient and less drag overall. The limit is given by the combination of available thrust and the actual mass of the aircraft, and it will climb higher during a trip as fuel is burnt off. The maximum range is possible at one particular lift coefficient, and to maintain this during a long trip means to increase altitude, so the lower density compensates the lower aircraft mass. Engine thrust is normally sized during design such that this optimum altitude can just be reached in normal operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On eastbound routes in controlled airspace, pilots are encouraged to fly at odd thousands of feet (depending on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/37/what-differences-are-there-in-flight-level-rules-internationally&quot;&gt;local rules&lt;/a&gt;), so the climb will not be continuous, but stepwise. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight/2808#2808&quot;&gt;this answer&lt;/a&gt; for more on separation rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a rather lengthy answer with more background on the theory how to pick the ideal flight condition for maximum range, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;this link&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-07-21T20:00:24.820" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7783" PostTypeId="2" ParentId="7764" CreationDate="2014-07-19T19:15:36.683" Score="4" Body="&lt;p&gt;IMO the only option is not board.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers altering flight paths sounds suspiciously like terrorists.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the airline tell the difference? Just because &lt;em&gt;he&lt;/em&gt; looks like an Arab doesn't make him a terrorist. Just because &lt;em&gt;she&lt;/em&gt; looks like a soccer mom doesn't mean she isn't.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-07-19T19:15:36.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7784" PostTypeId="2" ParentId="2472" CreationDate="2014-07-19T22:00:53.303" Score="1" Body="&lt;p&gt;The short answer is they don't know these are the final tracks for MH370 at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two lines more likely represent a range of probability between them defined either by variablities in aircraft cruise speed or variabilities from cumulative calculation errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plotting these paths with such certainty requires the last known position of MH370 to be known with certainty, but it isn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whilst the &quot;vector addition&quot; method is not the same as another navigation practice known as &quot;dead reckoning&quot; there are striking similarities such as the amplification of track errors. The entire process is founded on a string of assumptions all of which have to be correct for the final solution to work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is good reason to question the credibility of these assumptions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yQKHa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with this carefully plotted track is it assumes the last position of MH370 above Aceh at 2:22am is known with certainty. That is not the case at all. Malaysian evidence for MH370's last position is increasingly discredited. It is even questionable whether MH370 was in the Straits of Malacca at all? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yefiU.jpg&quot; alt=&quot;Radar track UAE343 overlay&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the alleged Butterworth radar image does not show the tracks of two other aircraft known to be in the same area at the same time. Why not?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another credibility problem is that Malaysia says the image which it showed to relatives at the Lido hotel on 21 March was from a military radar at Butterworth. In reality that radar is a Thales Raytheon GM400. This image is from a real Thales Raytheon GM400 display screen:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IaRH7.jpg&quot; alt=&quot;Thales Raytheon GM400 display screen&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The alleged radar image which satellite track plotters have relied upon is this from the Lido hotel on 21 March: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f6Tkw.jpg&quot; alt=&quot;Lido Hotel image&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The alleged radar image from the Lido hotel is actually the screen-shot taken from a civilian SSR radar. That being so it could not be an image of MH370 because as we are told ad nauseum, is that MH370's transponder was not working. No SSR radar could have tracked an airliner without a transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The credibility of Malaysia's radar image is so low that it is not unreasonable to call the image a hoax. They can't accurately plot the track of MH370 into the Indian Ocean based upon questionable radar claims like these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sadly another $90 Million taxpayer dollars will be wasted before people dare to question the Voodoo theology behind these calculations.  &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-07-19T22:00:53.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7785" PostTypeId="2" ParentId="7781" CreationDate="2014-07-19T22:13:23.810" Score="8" Body="&lt;p&gt;As Peter correctly notes, airliners which take off heavily laden with fuel and passengers struggle to reach their maximum altitude capability until they have burned off sufficient fuel. They achieve this by a technique known as a &quot;step climb&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this technique, they keep stepping up from one altitude to a higher one as their performance allows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prior to reaching Ukrainian airspace, MH17 would have flown through rather dense airspace over Europe where they may have had quite strict altitude stipulations, so that even if it had the performance to climb higher that may have been limited by other traffic inbound to Europe flying over the top of them.&lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="22726" LastEditDate="2019-03-27T21:03:46.613" LastActivityDate="2019-03-27T21:03:46.613" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7786" PostTypeId="2" ParentId="1857" CreationDate="2014-07-19T22:36:17.293" Score="18" Body="&lt;p&gt;Flying boats were a solution for long over water flights when engines were less reliable and could not produce sufficient power to lift large loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regular flying boat services between New Zealand and Australia which I am most familiar with, often never flew above 5,000ft. This meant they subjected passengers to considerable discomfort at the mercy of bad weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In areas where there were primitive support facilities and no runways, especially in the Pacific, these flying boats continued to operate into the early 'sixties, but as more and more runways were built the need for flying boats diminished and the cost increased. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tahiti and New Zealand operated the last scheduled routes for large flying boats in the Pacific. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shin Meiwa in Japan did propose a civil version of their impressive STOL US-1 which would have carried &gt;50 passengers in a pressurised cabin. India is interested in such aircraft for search and rescue but no orders have arisen for the civilian aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KWcIr.jpg&quot; alt=&quot;Shin Meiwa flying boat&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beriev in Russia has also developed an equally impressive Be-200 jet powered flying boat (smaller sibling of the A-40 Albatross). The Be-200 is offered as an amphibious airliner configuration, but so far airlines have not shown any interest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JpiFJ.jpg&quot; alt=&quot;Be-200&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-07-19T22:36:17.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7787" PostTypeId="2" ParentId="2160" CreationDate="2014-07-19T23:10:36.203" Score="1" Body="&lt;p&gt;Another Boeing 777 on 12th July 2014 suffered smoke in the cockpit and cascading loss of electrical systems, navigation displays and Comms in the cockpit. That was Continental Flight 201 which made an emergency landing on Midway island. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are disputed claims that flight 201's transponder also failed during the emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of MH370 it is acknowledged that the ACARS suffered a power interruption prior to log-on requests. It seems possible that the transponder was affected by whatever power interruption the ACARS suffered therefore it is not an automatic assumption that the transponder and ACARS were turned off deliberately.   &lt;/p&gt;&#xA;" OwnerUserId="2357" LastActivityDate="2014-07-19T23:10:36.203" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7788" PostTypeId="2" ParentId="7757" CreationDate="2014-07-20T02:24:44.387" Score="4" Body="&lt;p&gt;In short, the answer is almost certainly not. Surface to Air missiles capable of reaching the heights commercial air traffic flies at usually travel at a speed above the speed of sound, often surpassing mach 3. That means the missile is capable of reaching the height of common jet airways (30-35,000 feet) within ten seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the missile leaves a visible exhaust trail, as others have mentioned, the pilot's field of view is mostly restricted to a cone in front of the aircraft. Add to this the speed of the missile, and the likelyhood of it approaching from beneath and to the side of the aircraft, visually identifying it is very unlikely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A commercial pilot's options with regards to evading a SAM missile are pretty much nonexistent. The airplanes are not equipped with countermeasures (IR flares or chaff), and the speed and maneuverability of the missile far exceeds what the aircraft is capable of safely doing. Hollywood would have us think putting the aircraft into a dive is enough to put a missile off its tracks, but actually evading a missile, even for a military aircraft capable of much higher speeds and sharper turns, is usually dependant on active countermeasures in addition. The missile does not even have to hit the aircraft, they are designed to explode a short distance from them, spraying them with shrapnel that penetrates vital components.&lt;/p&gt;&#xA;" OwnerUserId="2918" LastActivityDate="2014-07-20T02:24:44.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7789" PostTypeId="1" AcceptedAnswerId="7833" CreationDate="2014-07-20T15:02:00.757" Score="24" ViewCount="51894" Body="&lt;p&gt;Both are single aisle, 3 by 3 seating planes.  Both are vaguely similar in length (with appropriate models).  But they have fairly different ranges.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For similar sized airplanes, why the big difference?&lt;/p&gt;&#xA;" OwnerUserId="80" LastActivityDate="2020-09-29T03:20:40.967" Title="What is different between a B737 and B757?" Tags="&lt;boeing-737&gt;&lt;boeing-757&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7790" PostTypeId="2" ParentId="7789" CreationDate="2014-07-20T15:53:36.293" Score="17" Body="&lt;p&gt;The 757 was designed after the oil shock of 1973 and represented the best which was possible in fuel efficiency. Therefore, its range is much greater, and with &lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow&quot;&gt;ETOPS&lt;/a&gt; certification it can be used on longer overwater trips. Besides, it shares the cockpit layout of it's twin aisle sibling 767, so flight crews could be certified on both with a single training. It replaced the Boeing 727, which is a bigger airplane than the 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 is a much older design, but has since then been redesigned twice. The latest models (737-600 to 737-900) were redesigned in the 1990ies and have a new wing and new engines, so their fuel efficiency is again state of the art. Both the 737 and the 757 inherited their fuselage cross section from the 707. With the stretched fuselage of the 737-900, the latest 737 it is almost as big as a 757-200.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="7532" LastEditDate="2015-09-30T15:39:03.780" LastActivityDate="2015-09-30T15:39:03.780" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7792" PostTypeId="1" AcceptedAnswerId="7793" CreationDate="2014-07-20T20:36:32.650" Score="11" ViewCount="5613" Body="&lt;p&gt;When a dual-engine aircraft (such as the B737, A320, A330, B777 or B787) has reached the point where it is too late to abort a take off, can it take off if one engine fails?&lt;/p&gt;&#xA;" OwnerUserId="2924" LastEditorUserId="14957" LastEditDate="2017-05-05T14:40:07.383" LastActivityDate="2017-05-05T19:14:56.860" Title="Can a dual-engine aircraft take off with only one engine?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7793" PostTypeId="2" ParentId="7792" CreationDate="2014-07-20T20:39:57.057" Score="18" Body="&lt;p&gt;It is a regulatory requirement (EASA CS 25) that commercial aircraft can safely fly should one of the two engines fail at any point of the flight, including takeoff at speeds beyond $V1$. (the maximum speed at which it can still stop before the end of the runway).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Control Following Engine Failure  1 An acceptable means of showing&#xA;  compliance with CS 25.143(b)(1) is to demonstrate that it is possible&#xA;  to regain full control of the aeroplane without attaining a dangerous&#xA;  flight condition in the event of a sudden and complete failure of the&#xA;  critical engine in the following conditions:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. At each take-off flap setting at the lowest speed recommended for&#xA;  initial steady climb with all engines operating after take-off, with –&#xA;  i. All engines, prior to the critical engine becoming inoperative, at&#xA;  maximum take-off power or thrust;  ii. All propeller controls in the&#xA;  take-off position;  iii. The landing gear retracted;  iv. The&#xA;  aeroplane in trim in the prescribed initial conditions; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. With wing-flaps retracted at a speed of 1.23 VSR1 with – i. All&#xA;  engines, prior to the critical engine becoming inoperative, at maximum&#xA;  continuous power or thrust;  ii. All propeller controls in the&#xA;  en-route position;  iii. The landing gear retracted;  iv. The&#xA;  aeroplane in trim in the prescribed initial conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/agency-measures-docs-certification-specifications-CS-25-CS-25_Amdt-3_19.09.07_Consolidated-version.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For a clip of this happening just as the aircraft is rotating, take a &lt;a href=&quot;https://www.youtube.com/watch?v=9KhZwsYtNDE&quot; rel=&quot;noreferrer&quot;&gt;look at this video&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/9KhZwsYtNDE?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simulator video of the &lt;a href=&quot;https://www.youtube.com/watch?v=n4Ucy1sD3MY&quot; rel=&quot;noreferrer&quot;&gt;procedure is also available&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/n4Ucy1sD3MY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2017-05-05T19:14:56.860" LastActivityDate="2017-05-05T19:14:56.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7794" PostTypeId="1" CreationDate="2014-07-20T22:04:22.827" Score="18" ViewCount="5134" Body="&lt;p&gt;In the event of a plane crash such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_17&quot;&gt;MH17&lt;/a&gt;, and the flight data recorders (FDR, a.k.a. &quot;black boxes&quot;) are potentially in the &quot;wrong hands&quot;, is it theoretically possible to:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;open the FDR and close it again without leaving traces?&lt;/li&gt;&#xA;&lt;li&gt;alter or selectively erase data of the FDR?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In other words, can an FDR professionally be tampered with as opposed to purely destroyed for the purpose of hindering an investigation?&lt;/p&gt;&#xA;" OwnerUserId="1868" LastEditorUserId="97" LastEditDate="2014-07-20T22:14:45.950" LastActivityDate="2014-07-21T17:33:19.340" Title="Can flight data recorders be hacked?" Tags="&lt;flight-data-recorder&gt;&lt;security&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7795" PostTypeId="2" ParentId="7794" CreationDate="2014-07-20T22:45:11.260" Score="18" Body="&lt;p&gt;Yes.  Black boxes aren't designed to be tamper-resistant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hard part is not the physical act of tampering with a black box, it's constructing a coherent false narrative of what happened during the time period.  The FDR records 80+ channels of data, which an investigator can correlate against each other, against data in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Quick_access_recorder&quot;&gt;quick access recorder&lt;/a&gt;, against &lt;a href=&quot;https://en.wikipedia.org/wiki/ACARS&quot;&gt;ACARS&lt;/a&gt; reports, and against the physical condition of the airplane itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, say you want to &quot;prove&quot; that an airplane's engines were shut down mid-flight, leading to a crash.  You could modify the FDR's record to show a throttle setting of &quot;closed&quot; and an engine RPM of 0, but the exhaust temperature would still be high, the fuel tank levels would still be dropping, and analysis of damage to the turbine blades would show a mix of axial and circumferential bending around the entire circumference of the blade disk, rather than the pure axial bending on a single side that would be expected if the engines had stopped spinning.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-07-20T22:45:11.260" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7797" PostTypeId="1" AcceptedAnswerId="7798" CreationDate="2014-07-21T03:37:36.373" Score="8" ViewCount="575" Body="&lt;p&gt;In view of &lt;a href=&quot;https://aviation.stackexchange.com/q/2031/128&quot;&gt;this other question&lt;/a&gt;, does the lead first enter or infiltrate the cabin air dispersion system, and then pervade or permeate the entire passenger cabin, thus every breathing passenger? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that the recirculated cabin air passes through HEPA filters, but does this resolve all the menaces and perils of lead? If not, how can passengers protect themselves? &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-07-22T13:41:07.850" Title="Does the lead in fuel harm passengers?" Tags="&lt;airliner&gt;&lt;passenger&gt;&lt;avgas&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7798" PostTypeId="2" ParentId="7797" CreationDate="2014-07-21T04:31:17.403" Score="23" Body="&lt;p&gt;Your question is based on an incomplete picture of how aircraft work, I'm afraid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a passenger on any major airline, the only lead you are likely to encounter is in the shielding on the security x-ray machines.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fact: leaded fuel is relatively uncommon&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First, tetraethyl lead is only present in what we call &lt;strong&gt;avgas&lt;/strong&gt; - it is most often sold these days as 100LL (100-octane low-lead) aviation gasoline. Avgas is only used in piston (reciprocating piston) engines. Very few commercial aircraft in this day and age are powered by piston engines; &lt;strong&gt;most airliners are turbine-powered (jet or turboprop engines) and are fueled by Jet A&lt;/strong&gt;, a variation on kerosene.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fact: exhaust shouldn't be in the cabin anyway&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Second, even if you happen to be flying in a light aircraft with a piston engine (or old, think Douglas DC-3 in Alaska), you shouldn't actually &lt;em&gt;encounter any lead&lt;/em&gt;. The cabin air intakes are positioned intentionally to avoid any exhaust entering the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If exhaust carrying lead particles was reaching the cabin, you've probably got bigger and more immediate problems with carbon monoxide poisoning anyway.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-07-21T04:37:55.390" LastActivityDate="2014-07-21T04:37:55.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7799" PostTypeId="1" AcceptedAnswerId="7805" CreationDate="2014-07-21T09:47:53.857" Score="16" ViewCount="6830" Body="&lt;p&gt;After seeing &lt;a href=&quot;https://www.youtube.com/watch?v=9KhZwsYtNDE&quot;&gt;this video of a 757's engine catching fire because of a bird&lt;/a&gt;,&#xA;I wonder:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What happens to the engine?&lt;/li&gt;&#xA;&lt;li&gt;Why does it periodically exhaust fire?&lt;/li&gt;&#xA;&lt;li&gt;Is this some safety feature?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2929" LastEditorUserId="1696" LastEditDate="2015-06-16T15:23:49.630" LastActivityDate="2019-02-02T07:29:17.217" Title="Why do jet engines sometimes spit out flames after ingesting birds?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;&lt;fire&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7800" PostTypeId="1" AcceptedAnswerId="7801" CreationDate="2014-07-21T13:32:57.740" Score="8" ViewCount="1850" Body="&lt;p&gt;Should an aircraft logbook stay inside of the airplane, or on the ground with maintenance? &lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="7793" LastEditDate="2016-10-17T14:19:07.240" LastActivityDate="2016-10-17T14:19:07.240" Title="Should the aircraft logbook be with the aircraft, or should it be on the ground?" Tags="&lt;anac-regulations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7801" PostTypeId="2" ParentId="7800" CreationDate="2014-07-21T13:41:36.197" Score="8" Body="&lt;p&gt;This is depending on which country the airplane is registered in, as the requirement to carry the logbook can be implemented per country, e.g. Germany requires the logbook to be carried onboard the airplane.&lt;sub&gt;[LuftBO §30 Abs. 5]&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-07-21T13:41:36.197" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7802" PostTypeId="1" AcceptedAnswerId="7814" CreationDate="2014-07-21T13:57:05.480" Score="22" ViewCount="4085" Body="&lt;p&gt;Watching this &lt;a href=&quot;http://youtu.be/9KhZwsYtNDE?t=6m58s&quot;&gt;video &lt;em&gt;(at 06:58 mark)&lt;/em&gt;&lt;/a&gt;, this plane had just made a mayday landing, due to a bird-strike. Because of the right engine being shutdown, it was forced to land immediately, with a full load of fuel. The added weight of the fuel, combined with loss of the additional stopping power of reverse thrust, caused the pilots to bear down on the brakes harder and longer than would be normal in an end-of-flight landing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot requests to hold on a taxi-way after vacating the runway, during which time the firemen come up to the plane to &quot;inspect the brakes.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do the firemen actually do when inspecting? Are they looking for fire? Glowing brake pads? Do they use an infra-red heat gauge?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="65" LastEditDate="2014-12-18T14:29:37.170" LastActivityDate="2015-06-10T17:14:45.863" Title="When the brakes are checked, what do the firemen actually do?" Tags="&lt;braking&gt;&lt;fire&gt;&lt;emergency-services&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7803" PostTypeId="2" ParentId="7802" CreationDate="2014-07-21T15:04:39.127" Score="7" Body="&lt;p&gt;The firemen are looking for fire.  If a blaze does break out, they will extinguish it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know the protocol for firemen using water to cool the brakes in absence of a visible fire.  Also, it looks to me like the firemen are more interested in the right engine than the brakes.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-07-21T15:42:32.353" LastActivityDate="2014-07-21T15:42:32.353" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="7804" PostTypeId="1" AcceptedAnswerId="7807" CreationDate="2014-07-21T15:12:38.750" Score="9" ViewCount="3477" Body="&lt;p&gt;Am I correct to assume that every electrical system on an aircraft can be manually switched OFF/ON by the Pilot OR is there indeed any system, on which the Pilot does not have the ability to switch OFF/ON ?&lt;/p&gt;&#xA;" OwnerUserId="2858" LastEditorUserId="917" LastEditDate="2018-01-14T14:48:53.463" LastActivityDate="2018-01-14T14:48:53.463" Title="Is there any electrical component on an aircraft which can never be turned off by a pilot?" Tags="&lt;safety&gt;&lt;aircraft-systems&gt;&lt;electrical-system&gt;" AnswerCount="3" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="7805" PostTypeId="2" ParentId="7799" CreationDate="2014-07-21T15:50:51.943" Score="23" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/7799/why-do-jet-engines-sometimes-spit-out-flames-after-ingesting-birds/7805#comment13214_7799&quot;&gt;RedGrittyBrick has commented&lt;/a&gt;, what happened in that video is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Compressor_stall#Axi-symmetric_stall_or_compressor_surge&quot; rel=&quot;noreferrer&quot;&gt;compressor surge&lt;/a&gt;. This is not really an engine fire, but a temporary backfire. To understand what is happening, look at this diagram of a turbine engine:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/8BkMh.png&quot; alt=&quot;Turbine Engine Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air is compressed in the front of the engine, fuel is injected and ignited, and then everything flows out the turbine section and the exhaust nozzle. The only thing supporting the compression at the front of the engine is the rotation of the compressor blades. There are many different things that could cause the compression to fail. In the event of a bird strike, these blades can be damaged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When that happens, there is highly compressed air in the combustion section, and there is no longer enough compression to prevent it from exiting the front of the engine. This causes the air to exit both the front and rear of the engine. The disruption in air flow happens too quickly for the engine control systems to react. This means the engine is still pumping enough fuel to run the engine at normal thrust, but there is no longer enough air flow to burn all that fuel in the combustion section. The result is that the fuel burns through the turbine and exhaust section of the engine, and behind the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once this compressed air has exited the engine, it will generally recover. The engine is not on fire, so once the excess fuel burns away, the flames are no longer visible. However, if the problem is still present (and damage from a bird strike would not go away), then the engine surges over and over until it is shut down or set to a lower, more stable power setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this is not so much a safety feature as physics taking over, and there is no real fire of immediate danger to the airplane. The engine system will automatically shut down the engine if it senses there is anything potentially very dangerous or that completely prevents the engine from running. While compressor surges can eventually damage the engine, it's not really a catastrophic event, and it is up to the pilots to assess the situation and shut the engine down if necessary. Reducing power to idle may sometimes be sufficient to stop the surges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a compressor surge, the flames are confined within the engine. There should be nothing to burn here besides fuel, so cutting off fuel will stop the fire. Actual engine fires are generally caused by flammable fluids leaking into hot areas around the engine, or the hot engine gases escaping from the air flow sections into surrounding systems. There are detection systems to alert the pilots of this situation, and the engine area is designed to contain a fire until the pilots can use the fire extinguishing systems to put such a fire out or at least get the plane back on the ground.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-06-16T15:23:09.457" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7806" PostTypeId="2" ParentId="7804" CreationDate="2014-07-21T16:06:14.513" Score="7" Body="&lt;p&gt;The pilot is generally given ultimate control over everything in the plane, when it comes down to it. Just like your car, they have to be able to shut everything down at the end of a flight. Take a look at this 737 classic overhead panel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vLaCc.jpg&quot; alt=&quot;737 upper panel electrical controls&quot;&gt;&lt;br&gt;&#xA;&lt;sub&gt;Original: &lt;a href=&quot;http://www.angelfire.com/il2/aphs/73oh2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.angelfire.com/il2/aphs/73oh2.jpg&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice all important switches have an &quot;OFF&quot; position. The black and red switch covers protect the main power connection switches, which you generally want to be &quot;ON&quot; during the flight. The BAT switch at the top connects the battery to the DC electrical bus. The switches below that control the switching of standby power, and the connection to the engine generators. At the bottom are the controls to transfer between different power sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are many other switches for different systems. Which systems have dedicated switches will depend on the make and model of the aircraft. As others have commented, some low level systems like engine control may be absolutely necessary for some things to function, and will not be easy to switch off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As ratchet freak commented, they also have access to the circuit breakers. Here is another picture from the 737, behind the first officer's seat. The pilot's handbook has instructions for what breakers should be switched off in what circumstances. Outside of those instructions, the effect on other systems of pulling one breaker could have unexpected consequences. The circuit breakers can be used to switch off equipment as a &lt;strong&gt;last resort&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iibs2.jpg&quot; alt=&quot;737 Circuit breaker panel&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-07-21T17:03:38.350" LastActivityDate="2014-07-21T17:03:38.350" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7807" PostTypeId="2" ParentId="7804" CreationDate="2014-07-21T16:37:13.653" Score="12" Body="&lt;p&gt;One example of a system that cannot be switched off by the pilot that is probably more common to all other airframes than just the one airframe I'm indicating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whenever electrical power is applied to a Gulfstream G550, whether it is powered by battery, generators, an apu, or some external power source, each engine's FADEC Electronic Engine Control (EEC) computer will be powered and the pilot can not switch them off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot could only indirectly turns them off by switching off all power sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, when the engines are running, he can't even do that since there is an engine-driven generator dedicated to powering the EECs in the event of a total power loss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, while the engine is running or even windmilling above 35% rpm, the EEC's dedicated generator is supplying all power to the EEC and there is no switch or circuit protection that can be manipulated by the pilot to interrupt it.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="2171" LastEditDate="2014-07-22T12:32:28.023" LastActivityDate="2014-07-22T12:32:28.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7810" PostTypeId="2" ParentId="701" CreationDate="2014-07-21T20:01:01.210" Score="2" Body="&lt;p&gt;A quick addition to the previous answers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger commercial aircraft also capitalize on the low-wing's benefits from a maintenance perspective.&lt;/p&gt;&#xA;" OwnerUserId="2934" LastActivityDate="2014-07-21T20:01:01.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7811" PostTypeId="2" ParentId="7802" CreationDate="2014-07-21T20:13:51.003" Score="5" Body="&lt;p&gt;Also there is a plug mounted on the wheel so if the brakes heat up the plug melts, so that the tire will not burst.  This would be something they would also check.&lt;/p&gt;&#xA;" OwnerUserId="2933" LastActivityDate="2014-07-21T20:13:51.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7812" PostTypeId="2" ParentId="7736" CreationDate="2014-07-21T21:44:23.000" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Since getting the cabin doors open is practically difficult&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, that's not the (main) reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's something called a wing ... which has engines mounted to it !&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not a very good idea to jump out of a door if you're likely to be sucked into an engine on your way out !&lt;/p&gt;&#xA;" OwnerUserId="2938" LastActivityDate="2014-07-21T21:44:23.000" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7813" PostTypeId="1" AcceptedAnswerId="7817" CreationDate="2014-07-21T23:58:24.363" Score="5" ViewCount="998" Body="&lt;p&gt;Related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/7774/what-effect-would-an-air-to-air-gps-jamming-system-have&quot;&gt;What effect would an air-to-air GPS jamming system have?&lt;/a&gt;, I'm wondering whether it is possible for a terrorist (or likewise, law enforcement) to manipulate GPS signals received by a jet, re-routing it elsewhere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I gather this would be far from a simple task, but how feasible is it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume that this is in uncontrolled airspace, so &lt;a href=&quot;/questions/tagged/atc&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;atc&amp;#39;&quot; rel=&quot;tag&quot;&gt;atc&lt;/a&gt; can't spot the change in flight path.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-03-04T18:06:03.120" Title="Can a GPS signal sent to a plane be spoofed?" Tags="&lt;security&gt;&lt;gnss&gt;&lt;terrorism&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7814" PostTypeId="2" ParentId="7802" CreationDate="2014-07-22T02:15:47.620" Score="21" Body="&lt;p&gt;There are specific protocols that procedurally are required to be followed. Insofar as brake inspection is concerned, it would have been obvious from the trucks that there was no brake fire. It's also obvious that there's not a major amount of smoke coming from the brakes. As they approached the landing gear, they would have smelled serious brake heating. Glowing brakes would be seen then if not sooner. A close visual inspection for very light smoke and sensing the heat coming off the brakes would give them an idea of the rate of brake vaporization. It's a subjective judgement based on what they see and feel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, tires that dangerously overheat will explode before melting, and that's why thermal plugs are used which melt and deflate the tire to prevent their exploding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a landing in Nandi, Fiji (short runway) with what turned out to be a tailwind in a 747-200 at near-max landing weight, we had to use max braking, and I called for huffers to cool things down, and of course for an inspection. I exited the aircraft as quickly as possible to see how bad things were. I was amazed and alarmed to see thick dark grey smoke pouring from the body and wing landing gear wheels. I thought we were close to having a fire. However, the ground personnel assured me that there was no cause for alarm, that the smoke was just brake vaporization that would shortly stop as they blew air on them. It did, and after refueling we departed without incident.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-07-22T02:15:47.620" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="7815" PostTypeId="1" AcceptedAnswerId="7819" CreationDate="2014-07-22T06:07:55.763" Score="22" ViewCount="21372" Body="&lt;p&gt;What is the phenomenon on a commercial airliner (say, a 737-800) where shortly after takeoff and before we reach 10,000 feet the engines feel like they slow down dramatically or even power off momentarily, then spin back up?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This happens fairly frequently when I'm flying and, although I'm used to it, it still takes me by surprise every time!&lt;/p&gt;&#xA;" OwnerUserId="2944" LastEditorUserId="2171" LastEditDate="2014-07-22T12:26:17.270" LastActivityDate="2015-12-15T15:13:40.783" Title="Why do the engines seem to power down and then back up after take-off?" Tags="&lt;takeoff&gt;&lt;jet-engine&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7816" PostTypeId="2" ParentId="7815" CreationDate="2014-07-22T07:18:34.370" Score="4" Body="&lt;p&gt;I'm sure someone will have a better answer, but I think its when the aircraft moves from a take off power setting to a climb power setting. &lt;/p&gt;&#xA;" OwnerUserId="2945" LastActivityDate="2014-07-22T07:18:34.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7817" PostTypeId="2" ParentId="7813" CreationDate="2014-07-22T07:19:57.343" Score="7" Body="&lt;p&gt;Spoofing GPS means broadcasting a false GPS signal - This is harder than jamming GPS which can be done relatively easily by broadcasting a strong random signal at the relevent carrier frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS receivers use GPS ephemeris tables which tell them where exactly they should expect each satellite to be. So the false GPS signal has to look enough like a real GPS signal that the receiver will accept it and use it's transmitted data in it's calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if, for example, the expansionist president of a country with advanced avionics capability decided to supply sophisticated equipment and the associated personnel to a separatist group in a neighbouring country, it might be possible for them to bring about this kind of result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been &lt;a href=&quot;http://www.digitaltrends.com/mobile/gps-spoofing/#!bjEDtv&quot;&gt;reports&lt;/a&gt; of this kind of spoofing actually happening, so it appears to be possible.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The U of Texas students built a GPS spoofing device for about $3,000. A pair of students, the “attackers,” then sat aboard the upper deck of the White Rose, where their GPS spoofer emitted a counterfeit signal slightly stronger than the real GPS signal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This was a yacht at sea, presumably out of sight of land on a featureless ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be more difficult to achieve this with an airliner, which have a variety of navigational instruments, including radio navigation beacon receivers. Inconsistent indications may alert the pilot to a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-GPS navigational instruments/systems that may be found in an aircraft include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot;&gt;VOR&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Distance_measuring_equipment&quot;&gt;DME&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Non-directional_beacon&quot;&gt;NDB/ADF&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Tactical_Air_Navigation&quot;&gt;TACAN-DME&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_data_inertial_reference_unit&quot;&gt;ADIRU&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-22T08:20:25.167" LastActivityDate="2014-07-22T08:20:25.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7818" PostTypeId="2" ParentId="7804" CreationDate="2014-07-22T07:36:22.763" Score="8" Body="&lt;p&gt;On an R22 helicopter (I quote from the Pilot Operating Handbook):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each tach, the governor, and the low rotor RPM warning horn are on separate circuits. Either the battery or the alternator can independently provide power to the tachs. A special circuit allows the battery to supply power to the tachs even if the master battery switch is off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is clear that the designers intend the the tachometers should work at all times, and there is no &quot;off switch&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To Falstro's point, the procedure for an electrical fire in flight includes turning off the alternator and battery master, and this is the precise moment when I am pleased to find that the tachometers are still working, since the governor and RPM warning horn are not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is true that there is also a circuit breaker for the tachometers, but there is no procedure, emergency or otherwise, which demands for these to be pulled. The only time I have ever known these to be used is by instructors to simulate emergencies for training purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The R22 is a pretty simple system and I don't know much about airliners but I imagine that it's impossible to access the flight data recorders in flight and I'm sure the designers try quite hard to make sure that they have power under all circumstances including catastrophic aircraft failure and hijack.&lt;/p&gt;&#xA;" OwnerUserId="2946" LastEditorUserId="2171" LastEditDate="2014-07-22T12:23:31.207" LastActivityDate="2014-07-22T12:23:31.207" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7819" PostTypeId="2" ParentId="7815" CreationDate="2014-07-22T09:35:18.367" Score="37" Body="&lt;p&gt;There are several kinds of power reduction which could happen after takeoff:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Cutback (noise reduction when the airplane is very low, after takeoff)&lt;/li&gt;&#xA;&lt;li&gt;Climb thrust&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Both are set on the CDU (Control Display Unit, the screen and keyboard of the FMC, Flight Management Computer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you describe a &lt;strong&gt;temporary&lt;/strong&gt; and &lt;strong&gt;dramatical&lt;/strong&gt; power decrease, this should be the &lt;strong&gt;cutback&lt;/strong&gt;. When you hear the power increase again, it must be that the setting goes from cutback to climb thrust.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;In the B737-800&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;The cutback option on the CDU&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;This is the CDU (Control Display Unit), where you set up the cutback. It is in the second page of TAKEOFF REF. Here is the screen before turning cutback ON.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/J0R8F.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uqKdS.png&quot; alt=&quot;Cutback off&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;ACCEL HT&lt;/strong&gt; : This is the height (above ground level) at which we will let the plane accelerate (we will lower the pitch a little bit and gradually retract flaps).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;EO ACCEL HT&lt;/strong&gt;: Same as above, but applies when one engine is not running (Engine Out Accelaration Height). This setting will be used in case of engine failure after takeoff.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;REDUCTION&lt;/strong&gt;: This is the height at which the thrust setting will go from TOGA to CLIMB. We need maximal thrust during takeoff, because it's a critical phase and it's safer. But at the same time, keeping this setting too long decreases the engines lifetime because of the high temperature. It also burns more fuel, it's noisier and less environment-friendly. That's the reason why the airplane won't climb with maximum thrust.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;But this question is about cutback. Here is CDU again after turning cutback ON.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VnVEX.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1wRcM.png&quot; alt=&quot;Cutback on&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;CUTBACK N1&lt;/strong&gt;: This will be the target N1 setting when the REDUCTION height will be reached. The Auto-throttle together with the EEC will arrange for maintaining this lower shaft speed (here you can see it's 84,6%). This will be a lot less noisy but will still provide enough power to climb!&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;EO ACCEL HT&lt;/strong&gt;: Same as above&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;REDUCTION&lt;/strong&gt;: At this height, cutback will happen and CUTBACK N1 will be the engines target N1 speed.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;RESTORE&lt;/strong&gt;: This is the height at which cutback is no longer needed, and climb thrust N1 setting will be the new N1 target for the engines (92.3% in this example).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Takeoff with cutback&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;This is the takeoff roll. IAS indicator is not active yet (below 45KIAS). Ground Speed is currently 35kt.&lt;br&gt;&#xA;N1 and TO/GA are displayed on the FMA (Flight Mode Annunciator) at the top of the PFD (Primary Flight Display). On the right, you can see on the ED (Engine Display) that the green marker is indicating TO thrust (because of TO/GA mode).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/XN4jT.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/el73Y.png&quot; alt=&quot;Takeoff roll&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Few seconds after the rotation. You can see at the bottom of the PFD the radio altimeter indicating 300ft AGL. We haven't reached the &lt;strong&gt;REDUCTION&lt;/strong&gt; height, so the cutback is not active yet. The ED still indicates TO thrust and the green markers are just below 100% N1.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/H60tr.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eHfku.png&quot; alt=&quot;After rotation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Few seconds after reaching &lt;strong&gt;REDUCTION&lt;/strong&gt; height. N1 is active on the FMA. Radio altimeter indicates 960ft AGL, this is above our &lt;strong&gt;REDUCTION&lt;/strong&gt; height, so the cutback should be active and our engines should be a little quieter. A look at the ED and we can see that the green target N1 marker is now indicating &lt;strong&gt;82.6% N1&lt;/strong&gt;. Our engines are still rotating faster than that (98% N1), and the EEC is currently decreasing the fuel flow arriving to the combustion chambers.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8PvtX.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n1Nl6.png&quot; alt=&quot;Cutback, 960AGL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;We are now reaching 2500ft AGL. This is below the &lt;strong&gt;RESTORE&lt;/strong&gt; height of 3000ft, so the cutback is still active, as shown by the ED. The green target N1 marker is indicating 83.0% N1 and the current N1 for both engines is also 83.0% N1. In 500ft, the N1 target speed should increase again to climb thrust settings.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/P1f2q.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/um052.png&quot; alt=&quot;Cutback, 2500AGL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;We've just reached the &lt;strong&gt;RESTORE&lt;/strong&gt; height (above 3000ft AGL), and we can see the green markers show 92.3%. We are back to the climb thrust settings and our plane is loud again! The flaps are still down, and the pink speed marker on the PFD just moved to the top. We are going to retract the flaps and slats, and accelerate to 250KIAS. It seems that RESTORE height is also the &lt;strong&gt;ACCELERATION&lt;/strong&gt; height when cutback mode has been turned on. &lt;em&gt;[I'm not sure, could a B737 pilot confirm this?]&lt;/em&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0qItH.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tqmi2.png&quot; alt=&quot;Restore &amp;amp; Acceleration height&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The flaps are up, our speed is now 250KIAS.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/fHIhX.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3AEl9.png&quot; alt=&quot;Acceleration done&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Further readings&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_21/quietclimb_story.html&quot;&gt;http://www.boeing.com/commercial/aeromagazine/aero_21/quietclimb_story.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.flaps2approach.com/journal/2013/6/29/avoiding-confusion-using-the-following-acceleration-height-t.html&quot;&gt;http://www.flaps2approach.com/journal/2013/6/29/avoiding-confusion-using-the-following-acceleration-height-t.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2452" LastEditorUserId="2452" LastEditDate="2014-07-31T07:50:36.690" LastActivityDate="2014-07-31T07:50:36.690" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="7821" PostTypeId="2" ParentId="1436" CreationDate="2014-07-22T11:02:49.010" Score="1" Body="&lt;p&gt;If you look at the tail point exhaust (next to the stabilizer), Airbuses have them positioned horizontal to the body and ended in a round opening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of Boeings, it is placed slightly below the horizontal cross-section of the fuselage and has an oval opening.&lt;/p&gt;&#xA;" OwnerUserId="2948" LastEditorUserId="946" LastEditDate="2014-07-23T10:21:55.203" LastActivityDate="2014-07-23T10:21:55.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7822" PostTypeId="2" ParentId="7815" CreationDate="2014-07-22T13:12:00.777" Score="13" Body="&lt;p&gt;Takeoff clearances are received from Tower ATC and contain an altitude limit.  &quot;Delta 632, cleared for takeoff runway 32L climb and maintain 3,000.&quot;  Upon reaching 3.000 the pilot must level off which means he must throttle back.  Then he will receive a further climb clearance from Departure Control and in most cases that clearance will be to a higher altitude.  The pilot must throttle up for that.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noise abatement procedures also affect this as well.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When at a non-busy airport ATC may clear the plane higher before he levels off, in which case the climb will be continuous.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The throttle down you notice is routine and normal. &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-07-22T13:12:00.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7823" PostTypeId="2" ParentId="701" CreationDate="2014-07-22T13:44:30.793" Score="7" Body="&lt;p&gt;Low wing aircraft also benefit that in a crash, much of the crash energy can go into the wings instead of into the fuselage. &lt;/p&gt;&#xA;" OwnerUserId="2951" LastActivityDate="2014-07-22T13:44:30.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7824" PostTypeId="1" CreationDate="2014-07-22T13:58:14.800" Score="50" ViewCount="40420" Body="&lt;p&gt;Why is a Boeing  737 NG engine not completely round in shape? It seems to be flat at the bottom and round at the top and sides. Earlier Boeing 737 versions (100 and 200) seem to have a more rounded shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GFzcj.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;BR&gt;(&lt;a href=&quot;https://www.eturbonews.com/19541/comair-limited-purchase-8-boeing-737-800-aircraft&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="2952" LastEditorUserId="14897" LastEditDate="2018-01-11T15:54:27.180" LastActivityDate="2019-12-06T20:41:40.743" Title="Why are the Boeing 737 nacelles odd shaped?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;boeing-737&gt;&lt;nacelle&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7825" PostTypeId="2" ParentId="7824" CreationDate="2014-07-22T14:10:16.510" Score="43" Body="&lt;p&gt;The engine in question is a &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;noreferrer&quot;&gt;CFM56&lt;/a&gt; turbofan engine which is larger than the JT8D the plane was originally designed for and thus has less ground clearance. This meant that they needed to flatten the bottom by moving the accessory gearbox to the side from the bottom and shrinking the fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56#Boeing_737&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the early 1980s Boeing selected the CFM56-3 to exclusively power&#xA;  the latest Boeing 737 variant, the 737-300. The 737 wings were closer&#xA;  to the ground than previous applications for the CFM56, necessitating&#xA;  several modifications to the engine. The fan diameter was reduced,&#xA;  which reduced the bypass ratio, and the engine accessory gearbox was&#xA;  moved from the bottom of the engine (the 6 o'clock position) to the 9&#xA;  o'clock position, giving the engine nacelle its distinctive&#xA;  flat-bottomed shape. The overall thrust was also reduced, from 24,000&#xA;  to 20,000 lbf (107 to 89 kN), mostly due to the reduction in bypass&#xA;  ratio.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also mounted the engine in front of the wing rather than below to get every bit of clearance they could.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O6leA.jpg&quot; alt=&quot;Front view&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/JdTvF.jpg&quot; alt=&quot;Side View&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2018-01-11T22:52:32.940" LastActivityDate="2018-01-11T22:52:32.940" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7826" PostTypeId="2" ParentId="7824" CreationDate="2014-07-22T14:33:59.807" Score="22" Body="&lt;p&gt;You are confusing the shape of the engine with the shape of the nacelle. Axial-compressor jet engines (standard on larger commercial jets) are invariably round and thin&lt;sup&gt;1&lt;/sup&gt;. Engines with a centrifugal compressor are fatter in the middle and will occasionally be lumpy shapes depending on the internal airflow (some engines completely reverse the flow of air through them, sometimes several times&lt;sup&gt;2&lt;/sup&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Positioning accessories like pumps, starters, generators, control boxes and minor things like mounting brackets are flexible. The engine manufacturer may dictate the position of some things like a gearbox, but if it attaches with a hose it can generally go anywhere the airframe designer wants to put it. The nacelle is then built to contain everything, not produce too much drag, not hit the ground, and preferably not cost too much to make. There's no reason we can't make hexagonal nacelles, we just choose not to.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;I consider the fan to be a bolt-on here, not part of the engine itself.&lt;/li&gt;&#xA;&lt;li&gt;See Pratt &amp;amp; Whitney PT-6 for an example.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-22T14:33:59.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7827" PostTypeId="1" AcceptedAnswerId="7828" CreationDate="2014-07-22T15:16:47.643" Score="6" ViewCount="283" Body="&lt;p&gt;By just going off the public information about a flight and what one knows about an aircraft, is it possible to construct a differ version of a flight recorder's data well enough to fool investigators?&lt;/p&gt;&#xA;" OwnerUserId="1701" LastActivityDate="2014-07-22T16:01:25.190" Title="Constructing flight recorder data" Tags="&lt;flight-data-recorder&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2014-07-23T06:56:32.543" ContentLicense="CC BY-SA 3.0" />
  <row Id="7828" PostTypeId="2" ParentId="7827" CreationDate="2014-07-22T16:01:25.190" Score="5" Body="&lt;p&gt;Theoretically? Yes.&lt;br&gt;&#xA;Practically? No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to construct an alternative Flight Data Recorder narrative good enough to fool investigators you would have to acquire a flight data recorder to feed the data to (this is the easy part). You would then need to feed the appropriate parameters to the flight data recorder to fill its memory (modern recorders can hold over 10 hours of data - this could encompass several flights that would have to be believably reconstructed - speeds and altitudes matching radar track data for example).&lt;br&gt;&#xA;A flight simulator could probably be rigged up to supply the data to the recorder, so the primary difficulty here would be matching your forgery to other data sources like RADAR tracks, radio calls, the CVR (unless you intend to falsify that as well), etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once filled with your falsified/reconstructed data the recorder would need to be injected into the chain of custody, which is perhaps more difficult. replacing one which has been recovered would require fooling the investigating agency, which has already seen, photographed, and cataloged the device they recovered (and would likely notice any subtle differences), or by finding the real recorder before investigators and replacing it with your forgery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it is not &lt;em&gt;impossible&lt;/em&gt; to do all of the above it is highly unlikely that anyone would succeed in such a scheme.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-22T16:01:25.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7829" PostTypeId="2" ParentId="7800" CreationDate="2014-07-22T16:08:00.197" Score="7" Body="&lt;p&gt;As an aircraft owner in the US I never kept a logbook in the aircraft.  I do this for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Someone from the FAA can come up and ask to the see the logbook when I am on my way someplace.  They can then tie me up for hours while they peruse the logs.  And if they find something they do not like ground the aircraft until we get the issue resolve.  That would strand me at some airport.  If the logbook is at home I can tell them to have their local office make an appointment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the log books are in the aircraft they can be stolen when the aircraft is parked.  Since the log books are a history of troubles repaired on the plane, service performed, etc, they are the authoritative history of the plane's health.  As such the log books represent a significant portion of the value of an aircraft (say 10-15%).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-07-22T20:11:02.600" LastActivityDate="2014-07-22T20:11:02.600" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7830" PostTypeId="1" CreationDate="2014-07-22T16:16:03.733" Score="1" ViewCount="82" Body="&lt;p&gt;I'd like to be aware of and include areas (in the requested maps) that might not be prohibited, but discriminated, mentioned, singularised, or warned in any way. An example: &lt;a href=&quot;http://www.newrepublic.com/article/118764/map-faa-tells-airlines-avoid-flying-over-these-countries&quot; rel=&quot;nofollow&quot;&gt;http://www.newrepublic.com/article/118764/map-faa-tells-airlines-avoid-flying-over-these-countries&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="128" LastEditDate="2014-07-23T08:00:22.450" LastActivityDate="2014-07-23T08:00:22.450" Title="Where can the latest maps marking all dangerous areas be found?" Tags="&lt;flight-planning&gt;" AnswerCount="0" CommentCount="6" FavoriteCount="1" ClosedDate="2014-07-24T15:26:55.697" ContentLicense="CC BY-SA 3.0" />
  <row Id="7831" PostTypeId="1" CreationDate="2014-07-22T16:17:17.537" Score="3" ViewCount="310" Body="&lt;p&gt;Further to &lt;a href=&quot;https://aviation.stackexchange.com/q/7830/128&quot;&gt;my other question&lt;/a&gt;, how can I find a realtime map of all flights that's combined with the foregoing map of all perilous zones? My goal is to see which flights may be overflying them, and in particular, if there are any commercial flights doing so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I only learnt of this via CNN, but want to predetermine this by myself: &lt;a href=&quot;http://edition.cnn.com/2014/07/22/world/asia/malaysia-airlines-plane-over-syria/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://edition.cnn.com/2014/07/22/world/asia/malaysia-airlines-plane-over-syria/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-08-26T13:13:51.873" Title="Where can a realtime map showing all flights and all dangerous areas be found?" Tags="&lt;flight-planning&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7833" PostTypeId="2" ParentId="7789" CreationDate="2014-07-22T17:21:40.560" Score="18" Body="&lt;p&gt;Although the 737 has grown over the years, the 737 and 757 remain in different size classes. Both models can be &lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot;&gt;ETOPS&lt;/a&gt; certified, although the 757 is more often used in long flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the time the 757 was introduced (in the 80's), the 737 classic series was current. For the &lt;a href=&quot;http://en.wikipedia.org/wiki/B737#Specifications&quot;&gt;737-400&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers: 146&lt;br&gt;&#xA;Length: 119 feet&lt;br&gt;&#xA;Wingspan: 95 feet&lt;br&gt;&#xA;Wing area: 1135 sq feet&lt;br&gt;&#xA;MTOW: 138,000 lb&lt;br&gt;&#xA;Takeoff distance: 8000 feet&lt;br&gt;&#xA;Range: 2160 nm&lt;br&gt;&#xA;Thrust: 2x 23,500 lbf&lt;br&gt;&#xA;Max fuel: 5,311 US gal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 757 was significantly larger. For the &lt;a href=&quot;http://en.wikipedia.org/wiki/B757#Specifications&quot;&gt;757-200&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers: 200&lt;br&gt;&#xA;Length: 155 feet&lt;br&gt;&#xA;Wingspan: 125 feet&lt;br&gt;&#xA;Wing area: 1951 sq feet&lt;br&gt;&#xA;MTOW: 255,000 lb&lt;br&gt;&#xA;Takeoff distance: 6500 feet&lt;br&gt;&#xA;Range: 4100 nm&lt;br&gt;&#xA;Thrust: 2x 43,500 lbf&lt;br&gt;&#xA;Max fuel: 11,489 US gal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 757 is about 35 feet longer, seats about 50 more passengers, and flies about 2,000 nm further (roughly twice as far). The extra range is due to the larger wingspan and longer fuselage, being able to carry more fuel. For this reason, the 757 is used on longer and busier routes, while the 737 is used on shorter, less busy routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 90's, both models were updated. The 737 was significantly upgraded, including new wings and a new engine, which increased its efficiency. The 737 NG series eventually included the &lt;a href=&quot;http://www.boeing.com/boeing/commercial/737family/pf/pf_900ER_back.page&quot;&gt;737-900ER&lt;/a&gt; model, currently the largest 737 model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers: 180&lt;br&gt;&#xA;Length: 138 feet&lt;br&gt;&#xA;Wingspan: 117 feet&lt;br&gt;&#xA;Wing area: 1341 sq feet&lt;br&gt;&#xA;MTOW: 187,700 lb&lt;br&gt;&#xA;Takeoff distance: 9843 feet&lt;br&gt;&#xA;Range: 3235 nm&lt;br&gt;&#xA;Thrust: 2x 28,400 lbf&lt;br&gt;&#xA;Max fuel: 7,837 US gal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/B757#Specifications&quot;&gt;757-300&lt;/a&gt; was also introduced. This was a stretched version of the 757-200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers: 243&lt;br&gt;&#xA;Length: 178 feet&lt;br&gt;&#xA;Wingspan: 125 feet&lt;br&gt;&#xA;Wing area: 1951 sq feet&lt;br&gt;&#xA;MTOW: 272,500 lb&lt;br&gt;&#xA;Takeoff distance: 7800 feet&lt;br&gt;&#xA;Range: 3595 nm&lt;br&gt;&#xA;Thrust: 2x 43,500 lb&lt;br&gt;&#xA;Max fuel: 11,489 US gal&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the more efficiency gains of the new 737 bring the range up to nearly that of the 757, the 757 remains significantly larger.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-07-22T17:21:40.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7834" PostTypeId="2" ParentId="7764" CreationDate="2014-07-22T19:30:39.633" Score="0" Body="&lt;p&gt;You have to remember that there is a route on the flight plan, and then there is the route the plane flies.  These are quite often not the same.  Air Traffic control can and does regularly does change routes once a plane takes off.  This allow ATC to control the sequence of plane to avoid congestion, reroute plane around bad weather, handle issues with weather, traffic, etc at the destination.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So objecting to the route based on what is planned may be an exercise in futility.  If you take another flight it is likely to be routed the same, or even if it is routed differently end up fly the same route.  There are only so many ways to get from point A to point B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to better ensure that the flight does not fly over a certain point would be to book from point A to point C to point B.  But that is likely more trouble than it is worth. &lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-07-22T20:15:26.443" LastActivityDate="2014-07-22T20:15:26.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7835" PostTypeId="1" CreationDate="2014-07-22T19:31:02.397" Score="12" ViewCount="965" Body="&lt;p&gt;Is is possible for a flight simulator software to simulate the real time scenario of landing an aircraft on a water body. There are instances of this (&lt;a href=&quot;http://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961&quot;&gt;Ethiopian Airlines Flight 961&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;US Airways Flight 1549&lt;/a&gt;) and the results were catastrophic/great  based on the type of water body they landed on and the situation which brought them there and several other parameters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I want to know if it is possible for a complex computer program to create this scenario effectively and thereby better equip the pilot ?&lt;/p&gt;&#xA;" OwnerUserId="2858" LastEditorUserId="2" LastEditDate="2014-07-22T20:00:48.417" LastActivityDate="2014-07-23T10:06:38.907" Title="Can water landing be simulated?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;flight-simulator&gt;&lt;ditching&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7836" PostTypeId="2" ParentId="7764" CreationDate="2014-07-22T20:00:47.583" Score="2" Body="&lt;p&gt;Assuming you could find a crew to listen to you, you would have to convince the captain operating the flight of your plea.  The captain then has to call dispatch and convince the dispatcher of the need for different routing.   If everyone is convinced, the dispatcher can re-dispatch you, which will probably result in a change to the ordered fuel and could result in weight restrictions due to the added weight of that fuel (and if I had to remove a passenger because of that, I know the first one I would boot...).  You'll also probably take a delay for the fuel people to come back out to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume this all went well, your captain got a new route filed and you are sitting back in your seat waiting to take off.  What you don't know however, is that many airports have preferred routing between them, and no matter what route you file between them, your clearance will always be the same.  So you went through all that work and now the crew is cleared back on the original routing (because dispatchers know to file these routes) and nothing has actually changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you object to the routing, your only real option is to choose not to board the airplane. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-07-22T20:00:47.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7837" PostTypeId="2" ParentId="7835" CreationDate="2014-07-22T20:12:08.757" Score="7" Body="&lt;p&gt;Technically yes, but I do not know of any simulator which includes this. The water forces can be calculated in the same way as the air forces, so I see no reason why it should't be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, model tests were made to check that a new airplane would behave well when landing on water. The simplest tests would use a catapult and launch the aircraft model into a lake, and more thorough tests use water tanks where the airplane model is pulled along the water surface while being suspended on a rig. This allows to measure forces, while the catapult launch will only show the dynamics of a water landing. Results like these could be used to calibrate the computer model, so you can be sure it behaves like the real thing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-07-22T20:12:08.757" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7839" PostTypeId="1" CreationDate="2014-07-22T21:08:59.773" Score="1" ViewCount="219" Body="&lt;p&gt;After an aircraft incident, finding the black box is important to investigate the causes, because it contains a lot of valuable recorded data.  The process of locating this can take a lot of time, and perhaps in some cases it will not be found at all, or deliberately sabotaged.  Both problems could be mitigated by continuously streaming flight data through a satellite uplink — or, if there is no coverage, buffer the data until there is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any aircraft do so, or are there any serious proposals to start doing so in the future?  What would be the largest obstacles?&lt;/p&gt;&#xA;" OwnerUserId="1626" LastActivityDate="2014-07-22T21:08:59.773" Title="Are there any proposals to continuously stream &quot;black box&quot; data?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2014-07-23T05:18:48.860" ContentLicense="CC BY-SA 3.0" />
  <row Id="7841" PostTypeId="2" ParentId="2183" CreationDate="2014-07-22T22:20:42.843" Score="2" Body="&lt;p&gt;Almost all aircraft have some sort of backup system for getting the gear down.  On the planes I have owned they were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Manual hydraulic pumps to pressurize the system with a car jack type handle.  You sort of pumped the gear down.  Obviously does not work too well if the problem with gear system is a no fluid (blown line or seal).&lt;/li&gt;&#xA;&lt;li&gt;Mechanical crank (21 turns to get down, 2 more to lock) that drove the gears if the electric motor died.  Good workout.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-22T22:20:42.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7842" PostTypeId="2" ParentId="1959" CreationDate="2014-07-22T22:42:24.760" Score="11" Body="&lt;p&gt;Excellent answers so far.  There are a couple other ways in which a jet engine can be started.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16 has the engine connected to a gearbox with a special, high-speed-balanced shaft.  There is a clutch where the shaft connects to the gearbox.  Also attached to the gearbox is a smaller turbine known as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Auxiliary_power_unit#Military_aircraft&quot; rel=&quot;nofollow&quot;&gt;Jet Fuel Starter&lt;/a&gt; (JFS), approximately the size of a large watermelon, also with a clutch. The gearbox also has hydraulic pumps and generators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To start the plane:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;the main engine is declutched from the gearbox&lt;/li&gt;&#xA;&lt;li&gt;the JFS is clutched to the gearbox&lt;/li&gt;&#xA;&lt;li&gt;hydraulic pressure is fed from an accumulator to a pump, causing it to work as a hydraulic motor, which turns the gearbox&lt;/li&gt;&#xA;&lt;li&gt;the turning gearbox spins up the JFS to the point that it reaches starting speed&lt;/li&gt;&#xA;&lt;li&gt;fuel is fed to the JFS, the ignition fires and it starts&lt;/li&gt;&#xA;&lt;li&gt;the JFS throttles up, producing about 200 horsepower&lt;/li&gt;&#xA;&lt;li&gt;when the JFS is running full tilt, the engine shaft's clutch engages&lt;/li&gt;&#xA;&lt;li&gt;the turning shaft rotates the main engine until it reaches start speed&lt;/li&gt;&#xA;&lt;li&gt;once the main engine reaches a particular speed, the JFS is declutched from the gearbox and shuts down&lt;/li&gt;&#xA;&lt;li&gt;the spinning engine brings the generators and hydraulics online, recharging the pressure in the accumulators for the next time it needs to start&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In some respects, this is similar to a bulldozer or other heavy equipment.  Many of them have a small &quot;pony motor&quot; with an electric starter, which then produces the power/torque combination necessary to start the main engine.  Once the main engine is running, the pony motor declutches and shuts off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other, older aircraft, such as the F-100 Super Sabre, used a small, explosive charge (start cartridge, essentially a large blank).  You'd install it into the engine.  The pilot would electrically fire it into the exhaust turbine, which would spin up the engine enough (you hoped) to get the whole thing to start speed, then engage the fuel and ignition systems.  If the cart failed to fire properly, you had to wait a certain period of time for it to cool off before you could remove it.  You wouldn't want it going off on the ramp (possible presence of fuel vapors) or in your hands (ouch!).&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="65" LastEditDate="2015-02-23T14:53:26.150" LastActivityDate="2015-02-23T14:53:26.150" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7844" PostTypeId="2" ParentId="2183" CreationDate="2014-07-22T23:50:06.283" Score="2" Body="&lt;p&gt;The Twin Comanche I used for my AMEL rating had an interesting mechanism.  First you had to disconnect the electric motor, then you  stuck this handle into a hole and crank it as far as you can.  Then you shift it to a second hole (that becomes usable after the first one is used) and crank on it again until it stops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not something you get to try until you need it though.  Once you pull the disconnect it requires an A&amp;amp;P to restore the system to normal operation.&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-07-22T23:50:06.283" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7845" PostTypeId="1" CreationDate="2014-07-22T23:58:50.120" Score="3" ViewCount="203" Body="&lt;p&gt;What is the nominal frequency of the aircraft terminal on flt 370? (The terminal used to provide the handshake with the satellite). The raw data provided by the accident team does not specify this frequency.  This frequency info would help in checking their BFO calculations.&lt;/p&gt;&#xA;" OwnerUserId="2966" LastEditorUserId="1696" LastEditDate="2015-02-24T23:27:37.107" LastActivityDate="2015-02-24T23:27:37.107" Title="What is the nominal frequency of the satellite communications terminal on MH370?" Tags="&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7847" PostTypeId="2" ParentId="2723" CreationDate="2014-07-23T00:23:35.063" Score="-3" Body="&lt;p&gt;The black box was invented by Professor Gordon Black at Farnborough in 1948 - hence the name 'black' box. See &lt;a href=&quot;http://www.newsandstar.co.uk/who-really-invented-the-black-box-1.745517&quot; rel=&quot;nofollow&quot;&gt;Who really invented the black box?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2961" LastEditorUserId="97" LastEditDate="2014-07-23T00:32:32.903" LastActivityDate="2014-07-23T00:32:32.903" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7848" PostTypeId="2" ParentId="2507" CreationDate="2014-07-23T01:47:59.217" Score="4" Body="&lt;p&gt;In short possibly...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But only if the aircraft is already heavily laden and there is a large mass shifting all at the same time. In the case of parachutists on a bare floor with no restraints, yes of course.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This 747 took off from Bagram airfield in Afghanistan with five armoured vehicles and they are thought to have broken free and shifted aft during take off:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OsZ4U.png&quot; alt=&quot;Bagram 2013&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X1eDW.jpg&quot; alt=&quot;Bagram crash 2013&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.businessinsider.com.au/bagram-airport-crash-video-surfaces-2013-4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Business Insider article&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2357" LastEditorUserId="2357" LastEditDate="2014-07-23T03:48:24.980" LastActivityDate="2014-07-23T03:48:24.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7849" PostTypeId="1" AcceptedAnswerId="7851" CreationDate="2014-07-23T04:26:34.390" Score="41" ViewCount="32561" Body="&lt;p&gt;Cockpits usually seem to have windows that are high up and it doesn't seem from pictures that they would allow a pilot to look down so easily while sitting in their seat. Please correct me if that is wrong because that is the basic assumption of this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then how do pilots know where the centerline is on the taxiway and runway? They always seem to taxi with nose wheel almost always on that line even when turning. Are there some instruments that help them? Or its the same logic as in a car as to how you find out where the lines are?&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="13197" LastEditDate="2016-04-29T19:46:44.603" LastActivityDate="2016-04-30T00:41:09.010" Title="How do pilots manage to keep aircraft on centerline during taxi?" Tags="&lt;taxiing&gt;" AnswerCount="7" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7850" PostTypeId="2" ParentId="7849" CreationDate="2014-07-23T05:32:01.300" Score="24" Body="&lt;p&gt;Airbus documentation claims the pilot can see 20° below horizon directly ahead (provided the seat is adjusted as recommended). Given the window of A320 is about 4m above ground, the closest point is about 11m ahead of them. And the nose wheel is more than 2m behind where the pilots sit. In larger aircraft it's of course proportionally further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's not that bad, but there is some problem. Out on the large taxiways seeing how the yellow lines extend to distance. It's really similar to a car. The closest point pilots see is further away, but the taxiways are proportionately larger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Near the terminal or assigned apron spot, external guidance is usually provided. The simplest method is by &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_marshalling&quot; rel=&quot;noreferrer&quot;&gt;ramp marshal&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7r959.jpg&quot; alt=&quot;air marshal&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large airports usually have &lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_Docking_Guidance_System&quot; rel=&quot;noreferrer&quot;&gt;visual docking guidance system&lt;/a&gt; that serves the same purpose:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rN57a.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several different systems exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last, some new aircraft have cameras that can provide video to cockpit. A380 has a camera behind the nose wheel for more precise taxiing and camera on tail that provides better perspective for judging clearance to obstacles as while wingtips are visible from cockpit in most aircraft, that angle makes it difficult to judge the clearance.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-07-23T05:32:01.300" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7851" PostTypeId="2" ParentId="7849" CreationDate="2014-07-23T06:05:41.400" Score="62" Body="&lt;p&gt;Aligning yourself in the middle of a straight taxiway isn't a problem. On the 747, if you put yourself in the middle of the taxiway as you see it beyond the nose, you'll be in good shape. If you're the captain, you can hold yourself a little left of the perceived center, but not much, because you're looking at from an eye level over 30 feet up as I remember. If the taxiway has those little metal reflectors sticking up on the centerline, you can play games trying to keep one of the nose wheels hitting them. You can just barely feel going across them. Or, since the nose gear is two wheels, you can play with getting the reflectors between the two wheels if you're really bored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turns on a taxiway present a bit more of a challenge insofar as keeping the center line because the nose gear is behind you, but one develops a feel for it. A 90 degree turn from a narrow taxiway onto another narrow taxiway is a little challenging, especially if the taxiway you're on T's into the one you're turning onto. All you'll see out the front window as you start the turn is grass. Also, on narrow taxiways, you can't see the taxiway out the side window from your normal sitting position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to do a 180 on a runway, you need to remember that when you first get yourself on, say, the right side of the runway, the nose gear isn't there yet, and the wing and body gear have even further to go.  You have to run yourself along the side of the runway a sufficient distance so that the airplane is aligned with the edge of the runway before you start your turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I found taxiing a 747 one of the more fun things in life.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-07-23T16:30:57.107" LastActivityDate="2014-07-23T16:30:57.107" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7852" PostTypeId="1" CreationDate="2014-07-23T08:36:36.367" Score="4" ViewCount="333" Body="&lt;p&gt;I ask in the spirit of aircraft spotting and would also prefer those with live ATC feeds, like &lt;a href=&quot;http://www.webcamhopper.com/ust/itami.html&quot; rel=&quot;nofollow&quot;&gt;Osaka&lt;/a&gt;. As of now, the visual quality is blurry and hazy, but perhaps this is due to low visibility and bad weather? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the side panel of that, I clicked on another for &lt;a href=&quot;http://www.webcamhopper.com/ust/narita.html&quot; rel=&quot;nofollow&quot;&gt;Narita&lt;/a&gt;, but this one doesn't capture the (active) runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an efficacious, systematic method to find all such webcams for substantive airports worldwide? Do such manifests or records already exist? I tried &lt;a href=&quot;http://forum.flightradar24.com/threads/352-Planespotting-All-Live-Airport-Video-Webcam/page3&quot; rel=&quot;nofollow&quot;&gt;a forum thread&lt;/a&gt; on FlightRadar24 which cites &lt;a href=&quot;http://airportwebcams.net&quot; rel=&quot;nofollow&quot;&gt;airportwebcams.net&lt;/a&gt;, but these are NOT streaming and realtime. &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="19" LastEditDate="2017-01-16T13:48:15.840" LastActivityDate="2017-01-16T13:48:15.840" Title="Where can I find a catalogue or lists of realtime, streaming (major) airport cameras?" Tags="&lt;airport&gt;&lt;website&gt;&lt;plane-spotting&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" CommunityOwnedDate="2014-07-25T03:02:19.263" ContentLicense="CC BY-SA 3.0" />
  <row Id="7853" PostTypeId="1" AcceptedAnswerId="7855" CreationDate="2014-07-23T09:17:47.907" Score="5" ViewCount="1253" Body="&lt;p&gt;Since Ben Gurion International Airport is closed, flights are being directed to &lt;a href=&quot;https://en.wikipedia.org/wiki/Ovda_Airport&quot; rel=&quot;nofollow&quot;&gt;Ovda&lt;/a&gt;, with a 3000 meter / 9,843 foot runway. &lt;strong&gt;Can large passenger jets, such as the Boeing 747, land at such an airport?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that a 747 at MTW needs about &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20080326081716AA1uXcN&quot; rel=&quot;nofollow&quot;&gt;10000 feet&lt;/a&gt; to land safely, but it can be done in a pinch at 6000-7000 feet. &lt;strong&gt;Would a commercial airliner fly flights to a temporary airport such as Ovda considering the shorter runway (i.e. not emergency conditions)?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if I may ask, in the linked thread a 747 pilot refers to the 747 as &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20080326081716AA1uXcN&quot; rel=&quot;nofollow&quot;&gt;&quot;a gigantic replica of the North American F-86&quot;&lt;/a&gt;. To what might he have been referring?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="1696" LastEditDate="2015-02-17T17:20:29.927" LastActivityDate="2015-04-06T18:43:24.930" Title="Can a 747 land at Ovda?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;boeing-747&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7855" PostTypeId="2" ParentId="7853" CreationDate="2014-07-23T14:11:11.937" Score="4" Body="&lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/7474sec3.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;747 AIRPORT PLANNING DOCUMENT - Boeing&lt;/a&gt;&lt;/em&gt; seems relevant but I don't understand it :-(&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has charts like this (assuming you want to be able to take off again sometime in the future - otherwise you might run out of 747s quite quickly)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tCdZG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think there's a landing equivalent if you need to know how much, ... erm ... cargo, to jettison.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-23T14:17:28.590" LastActivityDate="2014-07-23T14:17:28.590" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7856" PostTypeId="2" ParentId="7849" CreationDate="2014-07-23T14:58:13.463" Score="23" Body="&lt;p&gt;The question (&amp;amp; other answers) assume an airliner, but since that wasn't specified, I'll chime in for some tail draggers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some tail wheel aircraft, the short answer is &lt;strong&gt;they don't&lt;/strong&gt;.  If you watch a Pitts Special, a P-51 Mustang, a Gee-Bee, or other large engine wheel in the back airplane, you'll see them make a series of &quot;S-turns&quot; as they taxi.  The pilot sits too low to see forward past the engine when all 3 wheels are on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution is to &quot;zig zag&quot; down the taxiway.  That way you can look out one side then the other &amp;amp; have some idea where you are.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-07-23T14:58:13.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7857" PostTypeId="5" CreationDate="2014-07-23T14:59:58.870" Score="0" Body="" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-07-23T14:59:58.870" LastActivityDate="2014-07-23T14:59:58.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7858" PostTypeId="4" CreationDate="2014-07-23T14:59:58.870" Score="0" Body="Questions regarding the aviation regulations of the National Civil Aviation Agency of Brazil (Agência Nacional de Aviação Civil - http://www.anac.gov.br/)." OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-07-23T14:59:58.870" LastActivityDate="2014-07-23T14:59:58.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7859" PostTypeId="2" ParentId="7845" CreationDate="2014-07-23T15:43:51.043" Score="4" Body="&lt;p&gt;I looked through the report about the flight path analysis that is available from &lt;a href=&quot;http://www.jacc.gov.au/media/releases/2014/june/mr052.aspx&quot; rel=&quot;nofollow&quot;&gt;this page&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Appendix G they explain in more detail how the analysis was done. On page 56, they provide the details about the frequencies (emphasis added):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The uplink and downlink Doppler may be calculated from the relative movement of the aircraft, satellite and GES using the signal frequencies of &lt;strong&gt;1646.6525 MHz&lt;/strong&gt; (uplink) and &lt;strong&gt;3615.1525 MHz&lt;/strong&gt; (downlink).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means the aircraft terminal transmits (uplink) on 1646.6525 MHz and receives (downlink) on 3615.1525 MHz. However, it is not that simple.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft terminal adjusts its’ transmit frequency to compensate for the Doppler induced on the uplink signals by the aircraft velocity. Aircraft heading and ground speed are used to calculate the Doppler shift the signal would experience if the satellite was at its nominal location over the equator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is called Automatic Frequency Control (AFC) and Appendix G goes into more detail about all the factors involved, and provides tables with example calculations.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-07-24T16:16:22.137" LastActivityDate="2014-07-24T16:16:22.137" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7860" PostTypeId="2" ParentId="7849" CreationDate="2014-07-23T18:03:32.683" Score="4" Body="&lt;p&gt;In my experience taxing 727, 737, 757, 767, DC-9, MD80, L-1011 - if you kept the centerline between your legs you'd be ok. Sounds odd now that I type this and read it, but it worked.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2014-07-23T18:03:32.683" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7861" PostTypeId="5" CreationDate="2014-07-23T18:45:23.840" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-07-23T18:45:23.840" LastActivityDate="2014-07-23T18:45:23.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7862" PostTypeId="4" CreationDate="2014-07-23T18:45:23.840" Score="0" Body="Avgas, short for aviation gasoline, is an aviation fuel used to propel piston-engined aircraft." OwnerUserId="247" LastEditorUserId="22726" LastEditDate="2019-02-28T05:12:20.140" LastActivityDate="2019-02-28T05:12:20.140" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7863" PostTypeId="2" ParentId="1959" CreationDate="2014-07-23T19:53:31.877" Score="11" Body="&lt;p&gt;I guess now it is my turn to add exotic ways to start a jet engine.&lt;/p&gt;&#xA;&lt;p&gt;The Jumo 004 of the Me-262 and Ar-234 had a small piston engine in the central spike which was electrically started, but also could be hand-started by a mechanic. Did you ever note the hole in the middle of the spike, and the ring stuck in it (see the left picture below)?&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aiVSC.jpg&quot; alt=&quot;Jumo-004 intake&quot; /&gt;  &lt;img src=&quot;https://i.stack.imgur.com/07UB9.jpg&quot; alt=&quot;Riedel starter engine&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The ring was attached to a string which could be used to start the piston engine (Riedel starter engine, right picture). This could spool up the engine by itself up to 2000 RPM. At 500 - 1000 RPM the pilot would switch on the ignition. Now the starting combustion helped to spool up the engine further, until at 5000 RPM when the piston engine would decouple. Then the pilot could advance throttles slowly to 8700 RPM, the maximum.&lt;/p&gt;&#xA;&lt;p&gt;What could go wrong? A lot:&lt;BR&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The piston engine would not decouple.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Insufficient fuel flow, so the engine would not accelerate. In cold temperatures, the fuel pumps had to be switched on, but only up&#xA;to 3000 RPM.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The ignition would not start soon enough. Then the rotating engine would supply fuel to the combustion chamber, where it would collect and be blown into the rear engine fairing. When the combustion started, the collected fuel would burn as well, resulting in an engine fire.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The pilot would advance the throttles too quickly. This would supply too much fuel to the combustion chamber and heat up the turbine above its limit. Only with the higher airflow near the design&#xA;speed could the throttle be firewalled.  -&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The other starting procedure is that of the J-58s in the SR-71, which was remarkably similar. Only that the starter engine was a lot bigger and not part of the engine: It was a custom design of two tuned Buick 455 V-8s, coupled together on a cart and driving a vertical drive shaft that was driving the engine from a port under the engine nacelle. To start ignition, a special compound called triethylborane was injected, because the cold JP-7 (the special fuel for J-58s) would not ignite by itself. Once the engine could sustain itself, the cart was disengaged.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/8qmin.jpg&quot; alt=&quot;Starter engine cart for SR-71s&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The Buick engines would frequently fail and were later replaced by two Chevy big blocks. Also, the engines could be started with pressurized air. See &lt;a href=&quot;http://www.sr-71.org/blackbird/startercart.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;this link&lt;/a&gt; for more.&lt;/p&gt;&#xA;&lt;p&gt;What else could go wrong? That list is quite similar as well ...&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-06-21T18:47:59.920" LastActivityDate="2020-06-21T18:47:59.920" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7865" PostTypeId="2" ParentId="7849" CreationDate="2014-07-23T22:14:50.460" Score="2" Body="&lt;p&gt;To me it is just one of those things you get used to doing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I first started flying I would concentrate very hard while taxing and sometime miss the forest for the trees (what there was a plane at that intersection!!). But, after a while it becomes second nature.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A bigger issue was using your feet instead of your hands to turn left or right.  Also, learning to use differential thrust to bring a side around (turn left, increase right engine power) takes a bit of time.  And correct aileron position in gusty winds can also be fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since my experience is all in piston single and twins, and a few light turboprops, I wonder if the big boys have the same issues.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-23T22:14:50.460" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7866" PostTypeId="1" AcceptedAnswerId="7871" CreationDate="2014-07-23T22:20:04.790" Score="10" ViewCount="2891" Body="&lt;p&gt;Wikipedia and other sources assert that &lt;a href=&quot;https://en.wikipedia.org/wiki/Dead_reckoning#Air_navigation&quot;&gt;Charles Lindbergh used dead reckoning&lt;/a&gt; on his historic flight from Long Island to Paris but—likely being aimed at a broader audience—are short on specific technical details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With few or no landmarks to use as references, how was Lindbergh able to stay on course while over the Atlantic ocean?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2016-08-07T17:40:29.260" Title="How did Charles Lindbergh use dead reckoning over the Atlantic ocean?" Tags="&lt;navigation&gt;&lt;aviation-history&gt;&lt;oceanic&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7867" PostTypeId="1" CreationDate="2014-07-23T22:34:18.527" Score="8" ViewCount="796" Body="&lt;p&gt;There seems to be a problem with some of the data released by the satellite company Inmarsat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, the handshake at 00:10:58 on 7/03/2014.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the left column the difference in time-stamp between the ground station initiating the request and the receipt of the return signal from the aircraft is given as 1.928 seconds. However, the prior handshakes at 19:41, 20:41, 21:41, and 22:41 took 1.996, 1.997, 1.998, and 1.999 seconds.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would imply that the round trip distance between the ground station and the aircraft changed by about 13,000 miles in 1.5 hours.  What gives? &lt;/p&gt;&#xA;" OwnerUserId="2966" LastEditorUserId="959" LastEditDate="2015-02-19T12:17:41.807" LastActivityDate="2019-06-21T14:15:53.413" Title="How does one interpret the satellite data on flight MH370?" Tags="&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7868" PostTypeId="2" ParentId="7867" CreationDate="2014-07-23T22:46:15.433" Score="11" Body="&lt;h2&gt;TL;DR.&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Use the BTO not the difference in time-stamps for request &amp;amp; acknowledge.&lt;/li&gt;&#xA;&lt;li&gt;BTO is an offset in μs, not a round-trip time.&lt;/li&gt;&#xA;&lt;li&gt;There's a mean bias value (-495,679 μs) that includes the signal processing delays in equipment.&lt;/li&gt;&#xA;&lt;li&gt;The distance is ground-station to satellite to aircraft to satellite to ground-station.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Inmarsat data&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As I understand it, to calculate distance you should be starting with the Burst Timing Offset (BTO) not the difference between time-stamps in the &lt;a href=&quot;http://i2.cdn.turner.com/cnn/2014/images/05/27/flight.370.data.logs.pdf&quot; rel=&quot;noreferrer&quot;&gt;Inmarsat data&lt;/a&gt;. There are latencies in various stages in the electronic processing of messages, not all of these are distance related.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Time    BTO(μS)&#xA;19:41   11500&#xA;20:41   11740&#xA;21:41   12780&#xA;22:41   14540&#xA;00:10   18040&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;There's an example on page 54 of &lt;a href=&quot;http://www.jacc.gov.au/media/releases/2014/june/mr052_MH370_Definition_of_Sea_Floor_Wide_Area_Search.pdf&quot; rel=&quot;noreferrer&quot;&gt;MH370 - Definition of Underwater Search Areas&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8ejd4.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/822ja.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;The aircraft AND the satellite are in motion in three dimensions&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The satellite is at an altitude of around 35,811 km above the earth's surface, the satellite is moving cyclically north and south of the equator and the aircraft is flying over a roughly oblate spheroid so changes in it's distance from the satellite are not a simple function of changes in the aircraft position relative to the surface.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XMzOA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Not to scale. E&amp;amp;OE. etc&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;References&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.satellite-calculations.com/Satellite/Catalog/catalogID.php?23839&quot; rel=&quot;noreferrer&quot;&gt;Inmarsat 3-F1 satellite position&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.n2yo.com/?s=23839&quot; rel=&quot;noreferrer&quot;&gt;Inmarsat 3-F1 satellite tracking&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://i2.cdn.turner.com/cnn/2014/images/05/27/flight.370.data.logs.pdf&quot; rel=&quot;noreferrer&quot;&gt;Inmarsat raw log data for MH370&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.jacc.gov.au/media/releases/2014/june/mr052_MH370_Definition_of_Sea_Floor_Wide_Area_Search.pdf&quot; rel=&quot;noreferrer&quot;&gt;MH370 - Definition of Underwater Search Areas&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-28T10:24:14.143" LastActivityDate="2014-07-28T10:24:14.143" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7871" PostTypeId="2" ParentId="7866" CreationDate="2014-07-24T02:09:13.557" Score="5" Body="&lt;p&gt;It's actually &quot;ded&quot; reckoning (short for deduced), and it doesn't involve landmarks, it is simply flying a heading for a certain amount of time, that's it.  When you start adding in landmarks and things, that is called &quot;pilotage.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, visual navigation over land is mostly pilotage, with a bit of ded reckoning occasionally.  When you get over the water, like Charles Lindbergh, you do mostly ded reckoning.  When you do have a chance to use a landmark, you can update your location and basically restart your ded reckoning from a known point.  Lindbergh also used the stars to update his position and based new ded reckoning tracks on those positions.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-07-24T02:09:13.557" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7872" PostTypeId="2" ParentId="2622" CreationDate="2014-07-24T02:16:50.213" Score="-4" Body="&lt;p&gt;The only plausible reason is that the airline charges a different rate for the window seats, and you didn't purchase a ticket at the proper price point to get it.  It has no effect on the airplane whatsoever.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-07-24T02:16:50.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7873" PostTypeId="2" ParentId="3269" CreationDate="2014-07-24T02:54:45.443" Score="13" Body="&lt;p&gt;The answer to this question is protected as &lt;a href=&quot;http://en.wikipedia.org/wiki/Sensitive_Security_Information&quot;&gt;Sensitive Security Information (SSI)&lt;/a&gt; and can't legally be disclosed here.  Anyone who does answer the question either doesn't know what they are talking about, or faces steep legal consequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many, even most, questions relating to airline security (in the US at least ) are similarly handicapped.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-07-24T02:54:45.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7875" PostTypeId="1" CreationDate="2014-07-24T03:39:14.870" Score="6" ViewCount="1491" Body="&lt;p&gt;In a famous sequence from the TV show &lt;em&gt;24&lt;/em&gt;, a Boeing 727 is &lt;a href=&quot;http://24.wikia.com/wiki/Flight_520&quot; rel=&quot;nofollow&quot;&gt;forced to land on the 405 in Los Angeles&lt;/a&gt;. It is a well-known myth that &lt;a href=&quot;http://www.snopes.com/autos/law/airstrip.asp&quot; rel=&quot;nofollow&quot;&gt;the interstate highway system was set up as a series of airstrips&lt;/a&gt;. But would it be feasible to land a commercial airliner on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Interstate_405_(California)&quot; rel=&quot;nofollow&quot;&gt;405 highway&lt;/a&gt; from an aviation perspective, given that there were few if any cars on the road? (Of course, anyone who lives in LA will tell you that there is &lt;em&gt;never&lt;/em&gt; a time of the day or night when the 405 is not busy - so this is purely theoretical.)&lt;/p&gt;&#xA;" OwnerUserId="339" LastEditorUserId="572" LastEditDate="2014-07-24T16:44:34.210" LastActivityDate="2014-07-24T16:44:34.210" Title="Can a commercial airliner be landed on a highway, e.g. Highway 405 in Los Angeles?" Tags="&lt;landing&gt;&lt;emergency&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7876" PostTypeId="1" AcceptedAnswerId="7877" CreationDate="2014-07-24T05:41:07.867" Score="11" ViewCount="1939" Body="&lt;p&gt;Modern aircraft tend to have quite reasonable cockpit visibility. But throughout history there were some that had literally &lt;em&gt;no&lt;/em&gt; visibility directly forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best known example is probably Ryan Spirit of St. Louis:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/SpiritofStLouisCockpit.JPG/220px-SpiritofStLouisCockpit.JPG&quot; alt=&quot;Spirit of St. Louis cockpit closeup&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but there were others like &lt;a href=&quot;//en.wikipedia.org/wiki/Supermarine_S6&quot; rel=&quot;nofollow noreferrer&quot;&gt;Supermarine S6&lt;/a&gt;. Granted, they were all special purpose planes. But still, how did the pilot align with the intended runway and ensure the runway is clear? There was no ILS to help him, so it still had to be done visually. And how did he avoid obstacles and other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-12-04T21:36:12.170" LastActivityDate="2016-12-04T21:36:12.170" Title="How are aircraft controlled that have no forward view out of the cockpit?" Tags="&lt;pilot-technique&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7877" PostTypeId="2" ParentId="7876" CreationDate="2014-07-24T07:03:11.467" Score="12" Body="&lt;p&gt;You don't need a panoramic view to land, and in Lindbergh's time there was no other traffic to avoid. Navigation is easy enough through side windows (in many modern airplanes you can't see the ground out the front unless the nose is pointed down) and you can just yaw the plane left and right for the times you do want to line up with something. Airfields 100 years ago were quite literally fields, so you didn't need to be all that precise about it. Lindbergh had a periscope and was used to flying mail planes with the front seat occupied with the bag, so it wasn't anything new.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even today, tail draggers have basically zero forward visibility on the ground so they taxi by watching the edge of the pavement with the occasional sharp s-turn to check ahead. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-24T07:03:11.467" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7878" PostTypeId="2" ParentId="7875" CreationDate="2014-07-24T07:16:26.420" Score="5" Body="&lt;p&gt;It's possible, assuming the section chosen has no streetlamps, signs, overpasses etc. The police can block the traffic easy enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there would be zero reason to do so. If a plane has enough control to reach the highway, and enough advance notice to find a suitable part and block the traffic then it has enough control and time to reach one of the many airports in the region. Much less fuss for all concerned, and a much better equipped crash service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the prairies one could set up a fighter or bomber base on a random road, but again there's no need to - there's nothing nearby that would require it, heavy bombers or commercial planes would quickly destroy a normal highway and fighters could use the many civil airstrips in the area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Europe the math is different - opponents are a short flight away and destroying the airbases on both sides would be a top priority in any European conflict. See &quot;Highway strip&quot; in the usual reference for more details.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-07-24T07:16:26.420" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="7879" PostTypeId="1" AcceptedAnswerId="7880" CreationDate="2014-07-24T07:45:00.767" Score="10" ViewCount="7807" Body="&lt;p&gt;Is there any button which needs to be pressed when the pilot or co-pilot wishes to talk to ATC? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally in videos on YouTube they don't seem to be doing anything special other than speaking, but I believe that there's more to it. Probably the push buttons (like on a walkie-talkie) are located very close to their hands?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm generally asking about all aircraft that communicate with ATC, not any specific airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that I know the handshake stuff and the frequencies and the radio part of it. My question is only about whether they do or they don't have a push button when they have to send a message. It doesn't seem to be an always on thing because obviously that would clutter up the channel and ATC guys don't need to listen to what the pilots are talking in the cockpit routinely.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="1696" LastEditDate="2015-02-24T16:00:05.243" LastActivityDate="2015-06-03T11:40:31.987" Title="Is there a button that pilots push to transmit on the radio?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7880" PostTypeId="2" ParentId="7879" CreationDate="2014-07-24T08:57:26.567" Score="14" Body="&lt;p&gt;There is a &lt;strong&gt;push to talk&lt;/strong&gt; (PTT) button located at the yoke or sidestick, in small and large aircraft likewise. When the PTT button is not triggered, all communication is routed through the intercom and not broadcasted on the frequency. Once the button is triggered, communication is broadcasted on the active frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the below picture of a glider, it is located on top of the middle stick.&#xA;On the second picture is it behind the yoke, to be used with the index finger.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6UMhs.jpg&quot; alt=&quot;Glider Cockpit&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Glidercockpit.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiPedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2YHEu.jpg&quot; alt=&quot;B738 Yoke&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://l1011project.blogspot.de/2012_12_01_archive.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Private Blog&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-06-03T11:40:31.987" LastActivityDate="2015-06-03T11:40:31.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7881" PostTypeId="1" CreationDate="2014-07-24T09:13:50.300" Score="6" ViewCount="255" Body="&lt;p&gt;EASA STC certificate mentions the original issue of the Master Drawing List of the STC as &quot;Associated Technical Documentation&quot;. But the STC provider delivered a revised version of the MDL. Is the certificate which refers to the original issue still valid or shall I request a revised certificate for the STC? Can anyone advise me on this? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you in advance. &lt;/p&gt;&#xA;" OwnerUserId="1676" LastEditorUserId="1696" LastEditDate="2015-02-24T20:02:30.190" LastActivityDate="2015-02-24T20:02:30.190" Title="Is an EASA STC valid if it mentions issue 1 of a Master Drawing List that was later revised?" Tags="&lt;easa&gt;&lt;stc&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7882" PostTypeId="2" ParentId="7875" CreationDate="2014-07-24T15:59:48.043" Score="5" Body="&lt;p&gt;Maybe not the 405, but some roads in other countries where designed with usage by aircraft in mind.  IFIRC the autobahn was originally designed with that in mind, and NATO has conducted exercises using the autobahn as a runway.  There are some videos on YouTube showing this.  Also, there are videos of other countries using roadways for runways.  Parts of some roadways in Canada and Alaska have turnouts to allow aircraft to be parked after an off-airport landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, back to landing an airliners on the 405.  The 405 has too many light poles and other obstructions that would get in the way.  The strips of roadway used in the videos are devoid of these obstacles. &lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-24T15:59:48.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7883" PostTypeId="2" ParentId="7881" CreationDate="2014-07-24T16:14:07.657" Score="3" Body="&lt;p&gt;This sounds like a case where I would contact the STC holder and ask them what's up.&lt;br&gt;&#xA;In the USA I'm used to seeing STCs with the magic words &lt;code&gt;or later approved revisions&lt;/code&gt; (which means that the manufacturer can revise the document and get it re-approved without needing a new STC), but if a specific revision is called out and those magic words aren't present then later revisions are no longer &quot;approved data&quot; (or whatever the EASA equivalent term is) and technically can't be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all likelihood the two revisions are materially identical and this is just a &quot;paperwork problem&quot;, but you're better off being sure (and either getting a STC with the &quot;later approved revisions&quot; wording or getting the original issue of the drawing list so you have it in hand and comply with the STC you have) rather than having your local regulatory authority decide your installation is illegal because you didn't use approved data.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If there is a changelog on the document in question your mechanic could theoretically make the determination themselves - &lt;code&gt;Added drawing #123&lt;/code&gt; has no material effect if your installation doesn't reference that drawing. At that point it depends on how picky the folks approving your installation are though - again, they could say since it's a later revision it's not the &lt;em&gt;approved&lt;/em&gt; revision.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-24T16:14:07.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7884" PostTypeId="1" AcceptedAnswerId="7896" CreationDate="2014-07-24T17:15:34.933" Score="5" ViewCount="2590" Body="&lt;p&gt;I notice on some commercial flights that the aircraft can begin to swerve left-to-right during takeoff before we leave the ground. Sometimes this can become very exaggerated, very hard left-to-right swerving. This is typically from around mid-way through the takeoff run, becoming most severe immediately before takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My first thought was perhaps it is an inconsistency in the runway from the airport I frequent but have noticed it once or twice at other airports as well, and across different carriers. However, it feels more like when driving a car and you swerve, then overcompensate the other direction and it becomes a vicious cycle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other factors may include wind - but I've been in high-wind takeoffs before and it didn't have the same jerking motion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any explanation to this, or am I just paranoid?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;*Apologies for lack of knowledge re: terminology&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="2944" LastEditorUserId="19" LastEditDate="2015-02-18T20:00:54.997" LastActivityDate="2015-02-18T20:00:54.997" Title="What causes aircraft to swerve during takeoff?" Tags="&lt;commercial-aviation&gt;&lt;takeoff&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7885" PostTypeId="2" ParentId="7852" CreationDate="2014-07-24T18:52:07.470" Score="1" Body="&lt;p&gt;I don't have a website link with a list, but we can create a collaborative Community Wiki with all the webcams everyone knows &amp;mdash; feel free to edit this answer to add any you know!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Americas&lt;/h2&gt;&#xA;&#xA;&lt;h3&gt;Brazil&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.vejoaovivo.com.br/sc/florianopolis/aeroporto-hercilio-Luz.html&quot; rel=&quot;nofollow&quot;&gt;FLN/SBFL - Hercílio Luz/Florianopolis&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.vejoaovivo.com.br/sc/navegantes/aeroporto-de-navegantes.html&quot; rel=&quot;nofollow&quot;&gt;NVT/SBNF - Navegantes&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Canada&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.metcam.navcanada.ca/lb/index.jsp?lang=e&amp;amp;ui=lb&quot; rel=&quot;nofollow&quot;&gt;NavCanada Weather Webcams&lt;/a&gt; (only available at some airports, updated every 10 minutes)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Chile&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aipchile.gob.cl/camara/&quot; rel=&quot;nofollow&quot;&gt;All airports and aerodromes&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Europe&lt;/h2&gt;&#xA;&#xA;&lt;h3&gt;Germany&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dus.com/dus/webcams/&quot; rel=&quot;nofollow&quot;&gt;DUS/EDDL - Düsseldorf&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.koeln-bonn-airport.de/en/airport/airport-webcam.html&quot; rel=&quot;nofollow&quot; title=&quot;Cologne&quot;&gt;CGN/EDDK - Cologne Bonn/Köln-Bonn&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1538" LastEditorUserId="97" LastEditDate="2014-11-15T02:06:22.980" LastActivityDate="2014-11-15T02:06:22.980" CommentCount="0" CommunityOwnedDate="2014-07-25T03:02:19.263" ContentLicense="CC BY-SA 3.0" />
  <row Id="7886" PostTypeId="1" AcceptedAnswerId="7888" CreationDate="2014-07-24T20:01:59.077" Score="9" ViewCount="5330" Body="&lt;p&gt;In my simulator (flightgear) directional control during take-off of most tail-draggers is extremely difficult. When the tail lifts off, it immediately starts to turn to the left with no crosswind, but with sufficiently strong crosswind from the right it might be to the right. It takes very swift and hard rudder application to arrest and then easing the pressure to avoid overcontrolling. Otherwise the turn rate keeps increasing and ground loop occurs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is worse with some models than others. Some models are almost impossible to take off at full or normal take-off power and while most are, it is very difficult to keep them on the runway, because even if I manage to arrest the initial swerve, the aircraft is then turned a bit and attempts to re-align it tend to again provoke ground loop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controlling propeller aircraft with tricycle landing gear is on the other hand never difficult, even for the more powerful ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose some of the models are wrong. For example the Pitts S1C model is almost impossible to take off. But how difficult should it really be to keep the plane aligned?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, what would likely be wrong with model that is too difficult to control? Centre of gravity too far aft of the mail landing gear? Or something with the vertical stabilizer? There does not appear to be any parameter for vorticity of the propeller slip stream; it is apparently calculated from the power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is this one of the cases where simulator is much more difficult than the real thing, because in the real thing you have force feedback and get to use your built-in accelerometer (vestibular system) and in the simulator you don't?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="64" LastEditDate="2016-07-08T17:57:02.210" LastActivityDate="2016-07-09T19:24:58.640" Title="How difficult is it to avoid ground loop in practice?" Tags="&lt;flight-controls&gt;&lt;tail-dragger&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7887" PostTypeId="2" ParentId="7886" CreationDate="2014-07-24T20:28:22.023" Score="3" Body="&lt;p&gt;I have not flown that many taildraggers, but some can be kind of twitchy like you describe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like most things in flying the trick is to not get behind.  If you anticipate needing some rudder as you feed in power get the control input in before the power.  Also, remember as the aircraft picks up speed the control surfaces will be more effective, so you need to moderate your control inputs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also have to compensate for the descending prop blade causing the center of thrust to shift off center because of the high angle of attack of the prop blade as you start rolling.  This commonly called p-factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each plane, let alone model of plane, tends to be unique in it's handling characteristics. While I have never flown a Pitts I can imagine that since it has a lot power (big p-factor), short fuselage (short moment, lower longitudinal stability), and rather big control surfaces (small input, big effect) it would be a handful.  Maybe you should try something easier for a bit like a Piper and get that down.  Then work up to a stable plane like a Cessna 185, and a twitchier plane like a Citabria, and then onto the Pitts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I think the Pitts does not have flaps, so you will probably need to slip to a landing.  That is really fun and it also provided good runway visibility since you are coming in at an acute angle to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have fun,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jerry&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-24T20:28:22.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7888" PostTypeId="2" ParentId="7886" CreationDate="2014-07-24T20:48:29.710" Score="6" Body="&lt;p&gt;What you're experiencing is the natural tendency of an aircraft to turn left under high power.&lt;br&gt;&#xA;Several forces combine to cause this as shown in the diagram below:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/wA0Ph.jpg&quot; alt=&quot;Cause of left-turning tendencies&quot;&gt;&lt;br&gt;&#xA;(These forces are also discussed in &lt;a href=&quot;https://www.youtube.com/watch?v=T0vs2AMJDas&quot; rel=&quot;nofollow noreferrer&quot;&gt;this YouTube video&lt;/a&gt; which is worth a watch.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The left-turning tendencies are more pronounced in higher powered aircraft (more torque). They are even more pronounced in tailwheel aircraft when the tail comes up because you no longer have a third point of contact with the ground resisting the forces, and the pitch change exaggerates the effect of gyroscopic precession. (Similarly when the tail comes up in a strong crosswind the aircraft has an even higher tendency to weathervane into the wind, because there's no third point of contact with the ground fighting its tendency to pivot).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The position of the center of gravity relative to the gear also contributes to some of the differences in handling on the ground (and their tendency to ground-loop), but it's probably not the major factor in the difficulty you're describing.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In regard to your difficulty fighting the aircraft's left-turning tendency, part of this is undoubtedly the fact that a simulator has poor (zero) feedback compared to sitting in an actual aircraft, but some of it probably has to do with your technique: You're describing &lt;code&gt;very swift and hard rudder application&lt;/code&gt;, and frankly no aircraft is going to like that (and tailwheel aircraft will make their displeasure known in the swiftest possible ground-loop).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's called for instead are &lt;em&gt;smooth&lt;/em&gt; control inputs - advance the throttle slowly, feeding in enough rudder input to track the centerline as the engine power increases. Remember that ultimately you're balancing forces that are changing: Slipstream and torque reaction are more pronounced as the engine develops more power,  P-factor varies depending on the aircraft's pitch angle, and the effects of precession vary as you &lt;em&gt;change&lt;/em&gt; the aircraft's pitch angle (applying forces to the rotating propeller).&lt;br&gt;&#xA;While these forces are changing the force exerted by the rudder is &lt;em&gt;also&lt;/em&gt; changing, becoming more effective as you accelerate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the way these factors combine the corrective forces you need to apply with the rudder aren't constant, and your feet should be &quot;dancing&quot; on the pedals making &lt;em&gt;small&lt;/em&gt; corrections all the time as smoothly as you can (a little wiggle on the centerline is far preferable to stabbing at the pedals and making the aircraft pirouette on the runway).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since you're using a simulator you can practice all of this in a no-wind situation to get a feel for the aircraft and the sort of control inputs that will be required (and ideally you can start with a trainer aircraft like a J-3 cub, and move up to something with a bigger engine as you get comfortable). You can also do high-speed taxi runs (with the tail up) to get a good feeling for how everything interacts, without having to worry about breaking a perfectly good aircraft if you ground-loop.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Disclaimer: I've got all of 1 hour in a tailwheel aircraft and the best I can say for my advice above is &quot;by following that advice I didn't ground-loop the thing!&quot;&lt;br&gt;&#xA;  You can probably get far better advice from a CFI with tailwheel experience, or a tailwheel pilot who's done it far more (and probably far better) than me!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-24T20:48:29.710" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7889" PostTypeId="1" AcceptedAnswerId="7891" CreationDate="2014-07-24T21:02:48.500" Score="26" ViewCount="18412" Body="&lt;p&gt;I've been told before that the runways for large commercial aircraft have to be built to withstand a large amount of force.  But I'm wondering exactly how much it is?  When a 747 touches down, how much force is being imparted from the wheels to the tarmac?  And, further, how much force is imparted into the runway while the plan is braking right after touchdown?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus Points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How much weight does the gear + the wheels absorb and dissipate?&lt;/li&gt;&#xA;&lt;li&gt;I'm sure there's a range from a &quot;greaser&quot; landing with light braking all the way to whatever the highest the main gear is rated for, it would be nice to know both extremes and the mean.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-07-24T21:08:23.503" LastActivityDate="2016-09-01T20:39:42.663" Title="How much force does a 747 land with?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;runways&gt;&lt;aircraft-heavy&gt;&lt;airport-design&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7891" PostTypeId="2" ParentId="7889" CreationDate="2014-07-24T22:11:18.867" Score="34" Body="&lt;p&gt;I do not know the exact numbers for oleo stroke and so on, but this is how you would calculate this. A 747-400 weighs 400 tons on take-off and 296 tons on landing, maximum. See &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/startup/pdf/747_perf.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for the source of those figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next is the landing speed, this is approx. 160 knots = 82 m/s. Now let's assume the pilot has misjudged the height and does not flare, but slams the aircraft with the 3° approach angle into the runway. It is supposed to survive this, so let's just continue. This gives you a vertical speed of 4.3 m/s, and at 296 tons this is an energy of 2,750 kWs = 0.76 kWh, which needs to be dissipated by the landing gear. Now I make the assumption that the gear stroke is 0.5 m (those who know please put it in the comments, and I will correct the calculation). We have 0.5 m to decelerate a mass of 296 tons from 4.3 m/s to zero. If we assume a constant deceleration, the force will also be constant and the sink speed will decrease linearly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The average sink speed during this process is 2.15 m/s, so it will take 0.23 s and an acceleration of 18.5 m/s$^2$. Force is mass times acceleration, so the force is 5,473 kN or 1.23 million pounds. This is just the inertial force to stop the descent. While taxiing to the take-off position, the aircraft will press with 400 tons = 878,000 lbs on the runway, since the wings do not yet produce any lift. This shows that even a hard landing does not stress the landing gear so much - after all, the acceleration is just shy of 2 g, acting on a much lighter plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, the landing gear of a 747 is staggered, so the inner main gears will touch the ground first. Also, I expect that the force will not be constant along the whole gear stroke. This will change the details of this approximation, but the general magnitude should not be different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/jet-aviation-on-rough-airfields/7496#7496&quot;&gt;This answer&lt;/a&gt; goes into more details on how to calculate the damage an airplane will do to a given runway or apron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the braking stresses. The landing field length of a 747-400 is 2175 m, and let's just assume that the pilot forgot to use thrust reversers, aerodynamic drag was switched off that day, and all the braking power had to be supplied by the 16 main wheels. Let's also assume that the pilot uses 1200 m of that field length for braking (I'm just making this up to get to an upper limit of what force will act on the tarmac). Now we need to decelerate from 82 m/s to zero within 1200 m. Linear deceleration means an average speed of 41 m/s, so the whole process takes 29.27 s. Dividing speed by time yields a deceleration of 2.8 m/s$^2$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To bring the aircraft to a full stop, we have an energy of 995,152 kWs = 276.4 kWh to dissipate along a distance of 1200 m. Using again Newton's second law, we see that this requires a horizontal force of 829 kN = 186,322 lbs, which translates into 51,8 kN = 11,645 lbs per wheel. This is certainly more than what happens in reality, but to put it into proportion: The static load per main wheel at the maximum landing mass is 174 kN = 39,150 lbs (assuming that 4% of the mass is carried by the nose gear). This extreme (horizontal) braking force is still less than 30% of the (vertical) static load, which is well below of the maximum braking coefficient of an aircraft wheel on a dry runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&#xA;CGCampell correctly remarked that emergency procedures at take-off weight will produce the biggest braking loads. Now I will calculate the highest possible braking loads, and for this I need this plot of a polynominal for the braking coefficient, which is the ratio between vertical and horizontal forces before the tire skids. I do not know the source; I collected it somewhere in the past and never found a reason to doubt its validity.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/uW35x.png&quot; alt=&quot;tire friction coefficient&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly before the aircraft comes to a stop, the highest friction coefficient is reached, and then little lift is produced by the wings, so the vertical tire loads are those of the static case. At 96% of 400 tons acting on 16 wheels, this is 24 tons = 235,344 N = 52,907 lbs of downward force per wheel. Since the friction coefficient is 1 at low speed, the same load is transferred horizontally from each wheel to the ground, almost five times more than what I approximated for the landing above. Clearly, going to the limits produces much higher loads.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Formulas used in the calculation:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How to calculate the deceleration of a mass $m$ from a speed $v_0$ to $v_1$&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Energy has no absolute value, we just add or subtract energy. The amount of energy change $∆E$ between the aircraft at a speed $v_0$ and at a speed $v_1$ is:&#xA;$$∆E = \frac{m}{2}\cdot (v_0^2 - v_1^2)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The unit of energy is the Joule, which equals the Watt-second or the Newton-meter. Thus 1&amp;nbsp;J =&amp;nbsp;1&amp;nbsp;Ws =&amp;nbsp;1&amp;nbsp;Nm =&amp;nbsp;1&amp;nbsp;$\frac{\text{kg}\cdot \text{m}^2}{\text{s}^2}$. Metric units are neat, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In physics, energy $E$ equals work $W$, and work is performed when a force $F$ travels along a distance $s$. As does the braking force, acting on the moving aircraft:&#xA;$$E = W = F_{brake}\cdot s$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How do we get the rollout distance $s$?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We use the fact that the energy change due to deceleration equals the brake energy:&#xA;$$\frac{m}{2}\cdot (v_0^2 - v_1^2) = F_{brake}\cdot s \Leftrightarrow s =  \frac{m}{2\cdot F_{brake}}\cdot (v_0^2 - v_1^2)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How can we find the time $t$ it takes to slow the aircraft down?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the force is constant, the acceleration $a = \frac{m}{F}$ is constant, too. So the speed over time $v(t)$ is:&#xA;$$v(t) = v_0 + a\cdot t$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We decelerate, so $a$ is a negative number. But the same works for a positive acceleration, too. To find the time $∆t = t_1 - t_0$ we make use of the fact that v varies linearly over time, such that the average speed is the arithmetic mean between $v_0$ and $v_1$. And time is just distance divided by speed:&#xA;$$∆t = \frac{2\cdot s}{v_0 + v_1} = \frac{m\cdot s}{F_{brake}\cdot(v_0 + v_1)}\cdot (v_0^2 - v_1^2)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With such formulas it is always a good idea to compare the units on both sides. Yup, seconds, so the result is really a time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-09-01T20:39:42.663" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="7892" PostTypeId="2" ParentId="7886" CreationDate="2014-07-24T23:19:51.683" Score="7" Body="&lt;p&gt;Your simulator gives you a realistic experience: This is normal. What you experience is the gyro effect of the propeller and engine while you change the pitch attitude. When you lift the tail, the axis of rotation is changed and the engine-propeller combination pushed downwards, causing a &lt;a href=&quot;http://en.wikipedia.org/wiki/Precession&quot; rel=&quot;nofollow noreferrer&quot;&gt;precession&lt;/a&gt; force which acts orthogonally to the plane defined by the down movement and the axis of rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the engine is forward of the center of gravity, this precession force is pushing the nose sideways: Left for a propeller which spins clockwise (when observed from the pilot's viewpoint), and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to avoid a change in direction is to keep the tail to the ground with the stick aft until you know you are fast enough to lift the tail, and when you lift the tail up, you apply rudder simultaneously. Don't let the tail come up by itself!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I learned this in a Dimona motorglider. Now think of flying a small, light airplane where the propeller is bolted firmly to the heavy engine crankcase, both rotating. The airplane will dive or climb when you change direction! This is what pilots had to endure in the First World War, when they flew aircraft with rotary engines. When engines became more powerful, this became so bad that some aircraft were almost unflyable. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/700/uniform-turbine-rotation-direction/7425#7425&quot;&gt;this answer&lt;/a&gt; for more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That crosswind is turning the nose into the wind after lifting the tail should also be no surprise: While the main gear is still on the ground, the plane will weathervane into the wind once the tail is lifted.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-07-25T07:25:13.997" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7893" PostTypeId="2" ParentId="7884" CreationDate="2014-07-25T00:43:28.577" Score="1" Body="&lt;p&gt;I am not an expert, but it could be because the main Yaw control moves from the nose wheel to the rudder. During slow flight, you need to be more forceful on the rudder as there is not much control.&lt;/p&gt;&#xA;" OwnerUserId="2990" LastActivityDate="2014-07-25T00:43:28.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7894" PostTypeId="2" ParentId="3846" CreationDate="2014-07-25T18:28:07.407" Score="3" Body="&lt;p&gt;It is not prohibited in the US, but I don't think it's currently practiced anywhere.  There used to be a school called &lt;a href=&quot;http://www.nytimes.com/2009/07/05/business/05loan.html?pagewanted=all&amp;amp;_r=0&quot; rel=&quot;nofollow&quot;&gt;Tab Express&lt;/a&gt; that did something like this, but the most notorious one was an airline called &lt;a href=&quot;http://en.wikipedia.org/wiki/Silver_Airways&quot; rel=&quot;nofollow&quot;&gt;Gulfstream International Airlines&lt;/a&gt; that operated as United Express in Florida.  Gulfstream is now operating as Silver Airways and, as far as I know, has discontinued the practice of having the FO pay to be there.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-07-25T18:28:07.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7895" PostTypeId="2" ParentId="7884" CreationDate="2014-07-25T18:31:48.303" Score="5" Body="&lt;p&gt;Crosswind can cause it, especially if there are gusts involved.  It would be more common on turboprops as well since they have more left turning tendencies from the engines, such as torque, p-factor, etc.  In these airplanes the pilot has to compensate by holding right rudder, and sometimes they end up swerving a little bit as they try to find the right balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, the swerving is not nearly as bad as it feels, the farther to the back you are the more you're going to feel it as well.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-07-25T18:31:48.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7896" PostTypeId="2" ParentId="7884" CreationDate="2014-07-25T18:39:28.523" Score="9" Body="&lt;p&gt;I know you said that you don't think it's a crosswind, but honestly it most likely is.  As the plane speeds up and the wings start to generate more and more lift the plane is more easily affected by cross wind.  So, as you speed up, it gets harder and harder to keep the plane straight.  Throw in some gusts, and you're going to get some jerking motions as well.  Especially if that gust decreases the lift of the aircraft, the wheels suddenly catch the ground more and the craft is suddenly tugged harder than the pilot anticipated...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a video of a &lt;a href=&quot;https://www.youtube.com/watch?v=sUcQZK0hYlo&quot; rel=&quot;noreferrer&quot;&gt;Boeing 777 taking off in a heavy crosswind&lt;/a&gt; that should illustrate the point more.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-07-25T18:39:28.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7898" PostTypeId="1" CreationDate="2014-07-26T12:22:52.817" Score="12" ViewCount="1558" Body="&lt;p&gt;At all airports where I've looked out the window during taxi, the taxiway intersections have been painted with nice circular arcs connecting (the centerline of) each entry to the intersection with each exit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always assumed these lines were there to guide planes through the turns -- that is, if the nose wheel follows the curved line exactly then you're guaranteed that there'll be pavement under the path the main gear will follow, and there will be sufficient wingtip clearances for the aircraft types allowed to use the intersection, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in &lt;a href=&quot;https://aviation.stackexchange.com/questions/7849/how-do-pilots-manage-to-keep-aircraft-on-centerline-during-taxi&quot;&gt;this question&lt;/a&gt; it comes to light that pilots can't even &lt;em&gt;see&lt;/em&gt; the curved centerlines while they're turning and rely on spatial intuition instead. Very well, that seems to work fine in practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which leads to the question: &lt;strong&gt;Who are the curved centerlines for, then?&lt;/strong&gt; What would go wrong if they weren't there and instead just the straight centerlines of the intersecting taxiways continued through?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possibly the pilots of &lt;em&gt;smaller&lt;/em&gt; aircraft than the intersection is built for (say, a Dash-8 in an intersection that can take A380s?) can see the curved lines ahead of them while they turn. But in that case they should have plenty of room to do the turn by intuition too, right?&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-07-26T15:49:41.577" Title="What are the curved centerlines at taxiway intersections for?" Tags="&lt;taxiing&gt;&lt;airport-markings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7899" PostTypeId="1" AcceptedAnswerId="7900" CreationDate="2014-07-26T12:27:15.640" Score="0" ViewCount="385" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4ZKsU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the above figure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why the search is conducted to the red boxed area in the figure. while the actual route of Flight MH 370 is the green line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last known position is on the flight path, then&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not search on &lt;strong&gt;East/South China Sea &amp;amp; Bay of Bengal&lt;/strong&gt; ?&lt;/p&gt;&#xA;" OwnerUserId="2235" LastActivityDate="2014-07-27T13:03:16.807" Title="Why Search for MH 370 in this area?" Tags="&lt;airliner&gt;&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7900" PostTypeId="2" ParentId="7899" CreationDate="2014-07-26T13:04:36.860" Score="9" Body="&lt;p&gt;The initial search efforts did indeed take place in the South China Sea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interest moved to the Bay of Bengal after new evidence from military radar surveillance showed that the aircraft had turned west across the Malaysian Peninsula after contact was lost over the South China Sea. It took some time for this evidence to surface because the performance and capabilities of military radar systems are usually closely kept secrets -- presumably a lot of people in the military hierarchies had to sign off on releasing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later still, additional analysis pointed to an area in the &lt;em&gt;south&lt;/em&gt; Indian Ocean. It turned out that a single communication system aboard the plane had kept working for many hours after the South China Sea loss-of-contact. This is a satellite-based system that is usually used for routine maintenance messages, &lt;em&gt;not&lt;/em&gt; for navigation or accident investigation. It took many weeks to get from &quot;the plane was still alive for many hours&quot; to &quot;it went to the south Indian Ocean&quot;, through clever and painstaking analysis of data that the satellite company had originally collected for the purpose of tracking the health and performance &lt;em&gt;of the satellite itself&lt;/em&gt;, rather than as a way to locate planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the information used was how long it took for the aircraft to respond to the satellite each time it checked in (which gave the distance from the satellite to the aircraft at that time), plus minor variations in the RF frequency the aircraft responded at (which combines to give some information about its heading and velocity). The current search areas are the result of that information combined with &quot;reasonable assumptions&quot; about which speed the aircraft was cruising at during this period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some time the best analysis of the satellite data could only say that the last contact must have been &lt;em&gt;either&lt;/em&gt; in the south Indian Ocean &lt;em&gt;or&lt;/em&gt; somewhere around Afghanistan, but the &quot;northern corridor&quot; was later excluded by more detailed analysis. (It was never considered very likely, since it was much harder to imagine how the plane could stay undetected over land, where it ought to have been in view of many primary radar systems than over the ocean, outside of direct radar coverage).&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-07-26T13:04:36.860" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7902" PostTypeId="2" ParentId="7898" CreationDate="2014-07-26T15:49:41.577" Score="10" Body="&lt;p&gt;The line along taxiway centreline is meant to provide guidance before initiating the turn. You're right that in a large aircraft they would lose sight of the centreline when they're over it, but it gives the pilot an idea of where they need to keep the nose in order to keep the outer main wheels behind them on the taxiway surface. &lt;/p&gt;&#xA;&lt;p&gt;For example, in Canada, Transport Canada document TP312 (Aerodrome Standards and Recommended Practices) define how you need to place the centreline in order for the outer main wheels to remain at least a certain distance from the taxiway edge. (I believe the United States would have very similar rules; I just don't know the names of the appropriate documents)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Taxiway Curves&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;3.4.1.6 Recommendation - Changes in direction of taxiways should be as few and small as possible. The radii of the curves should be compatible with the manoeuvring capability and normal taxiing speeds of the aeroplanes for which the taxiway is intended. The design of the curve should be such that, when the cockpit of the aeroplane remains over the taxiway centre line markings, the clearance distance between the outer main wheels of the aeroplane and the edge of the taxiway should not be less than those specified in 3.4.1.3.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Think about when a large aircraft has to make a big turn (&amp;gt;90degrees). If there was no indication on the surface about how to take the turn in a large aircraft, you could inadvertently take it too early and run the main wheels off the pavement.&lt;/p&gt;&#xA;&lt;p&gt;Here's an example of an aircraft following the centreline with its nose as best as possible in order to keep the main wheels in the right spot. &lt;img src=&quot;https://i.stack.imgur.com/M5oGr.gif&quot; alt=&quot;taxiway curves&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-07-26T15:49:41.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7903" PostTypeId="2" ParentId="2920" CreationDate="2014-07-26T17:29:33.620" Score="11" Body="&lt;p&gt;It's hard to find a general pattern in radial vs inline engines in WW2.  Each country had engine manufacturers that produced the engines they were good at.  An important consideration was how the engine performed at altitude, which required complex superchargers or turbochargers.  In the US, the radial was far more developed.  The only US inline engine to see much service was the Allison V1710, which lacked a quality supercharger.  Turbocharged V1710s powered the P-38, making it an effective fighter at altitude.  The Pratt and Whitney R2800 radial was used in the Hellcat, Corsair, and P-47.  The Hellcat and Corsair were supercharged and performance fell off above 20,000 feet, not a problem for a naval fighter.  The P-47 was turbocharged.  The great size of the Thunderbolt was due to turbocharger ducting leading from the engine to the intercooler and back to the engine.  The turbocharger allowed the P-47 to be effective at high altitude.  The P-51 switched from the Allison V1710 to the Packard V1650, a license built Rolls Royce Merlin.  The V1650 had a better supercharger for altitude performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the UK, Rolls Royce produced the superb Merlin.  It was so good that the Seafire and Barracuda carrier aircraft used it.  As the war progressed, RR produced the Griffon, Napier the inline Sabre, and Bristol the Hercules and Centaurus radials.  All of these engines were capable of driving a high speed fighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Germany switched the FW-190 from radial to inline in the D model in search of altitude performance as the BMW radial lacked a good high altitude supercharger.  The original FW-190 owed its existence to not using the valuable inline engines needed for the Bf-109.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Japan and Italy never developed effective inlines.  The Ki-61 fighter was mediocre with a German designed inline and became the effective Ki-100 with a radial.  They also switched the D4Y dive bomber from inline to radial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the inline was more streamlined the radial could use the air cooling to produce thrust.  The air comes in cold and leaves hot (like a jet).  The radial saved weight by eliminating the liquid cooling system but the inline could be run more intensively because the engine cooling was more effective, resulting in smaller engines for the same power output.  The radial was less vulnerable and eliminated the logistics of liquid coolant.  By the way, about 50% of the cooling in a radial is from the oil, so even a radial is partially liquid cooled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the war, every airliner before jets used radials with one exception (I can't remember which) powered by the RR Merlin.  Modern manufacturers don't need the massive power in the smallest weight and volume possible so they choose simpler designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that the aircraft designers used what they had and only switched from radial to inline or vice versa when forced to.  The companies that started the war making inlines continued as did the radial manufacturers while aircraft designers used what they could access. &lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2014-07-26T17:29:33.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7904" PostTypeId="2" ParentId="7849" CreationDate="2014-07-26T17:30:17.133" Score="9" Body="&lt;p&gt;Lets turn this question around.  How do you stay in your lane when driving (not everyone can do this well)?  Unless you are looking directly to your near side, you can't see the line on that side and you certainly cannot see the lines on the far side.  So how do you stay centered in the lane?  You use context cues and spatial awareness, extending the lines that you see the places they go that you cannot see.  You know your vehicle and roughly where the lines you can see need to be visually placed to ensure you are in the lane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes work the same way.  We see the taxiway markings ahead of us and we can infer where they are under us.  We know our airplanes and where these markings should be relative to cues we have in the airplane to put the plane on the centerline.  If there is one thing pilots tend to be good at, it is spatial awareness and keeping the airplane on the centerline is on application of that skill.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-07-26T17:30:17.133" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7905" PostTypeId="2" ParentId="5026" CreationDate="2014-07-26T22:02:25.187" Score="1" Body="&lt;p&gt;The missile motor has a UV signature that can be detected.  Newer IR sensors can be fused to a UV sensor and generate a warning.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2014-07-26T22:02:25.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7906" PostTypeId="2" ParentId="3782" CreationDate="2014-07-26T22:27:40.000" Score="0" Body="&lt;p&gt;Economics.  Some innovations in engine technology that promise to lower fuel consumption for an SST can be applied to subsonic airliners keeping subsonic airliners ahead financially. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also the question of speed.  Aluminum is sufficient for an aircraft up to Mach 2.2.  Beyond that requires steel or titanium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, a plane with a max speed of Mach 2.2 is less than 3 times as fast as today's jetliners.  Counting taxiing, acceleration, and climb, this makes the SST's time advantage for the trip even less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SST will have a lower lift over drag ratio in all parts of the flight envelope compared to a subsonic airliner.  It will have greater parasite drag due to the greater speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane with speed over Mach 2.2 is built, it will be heavier and therefore burn more fuel.  It seems there is no sweet spot for SST speed.  The sweet spot seems to be Mach .85 or hypersonic where the craft can exit the atmosphere.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="2923" LastEditDate="2014-07-27T18:36:28.500" LastActivityDate="2014-07-27T18:36:28.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7908" PostTypeId="2" ParentId="2702" CreationDate="2014-07-27T10:17:13.657" Score="2" Body="&lt;p&gt;Simply: Flight Director is a system that computes desired pitch and roll from parameters like heading, altitude, vertical speed. Then an autopilot computes control surfaces deflection from given parameters: pitch and roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So: Pilot sets altitude, heading for Flight Director.&#xA;Flight director then computes pitch and roll for Autopilot (and human pilot, too).&#xA;If Autopilot is engaged, then it computes control surfaces deflections and moves the surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight Director is also displayed on PFD in some way, so if Autopilot is disengaged, the human pilot can still fly to follow FD's directions.&lt;/p&gt;&#xA;" OwnerUserId="3008" LastActivityDate="2014-07-27T10:17:13.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7909" PostTypeId="2" ParentId="7831" CreationDate="2014-07-27T12:18:28.203" Score="2" Body="&lt;p&gt;Actually what constitutes a &quot;perilous zone&quot; is arbitrarily decided by countries or airlines . Ergo, there are no zones that have been defined by the International Civil Aviation Organization as perilous .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/Pages/default.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.icao.int/Pages/default.aspx&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example as on this date British Airways and Qantas  have demarcated Ukrainian airspace as dangerous and is therefore avoiding it .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as a realtime map of flights are concerned who may take a look at Flightradar24&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flightradar24.com/20,77/7&quot; rel=&quot;nofollow&quot;&gt;http://www.flightradar24.com/20,77/7&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-07-27T12:18:28.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7910" PostTypeId="1" AcceptedAnswerId="7911" CreationDate="2014-07-28T03:36:10.043" Score="9" ViewCount="9647" Body="&lt;p&gt;Why is it that a larger volume of air moving slower is a more efficient means of propulsion than a smaller volume of air moving faster?  (This is true up to a given speed, obviously, as supersonic aircraft use lower BPR engines).&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2014-07-28T05:45:43.087" Title="Why is a higher bypass ratio more efficient at lower speeds?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7911" PostTypeId="2" ParentId="7910" CreationDate="2014-07-28T04:57:11.667" Score="13" Body="&lt;p&gt;Because bigger reaction mass with lower speed carries away less energy for the same momentum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To produce &lt;em&gt;thrust&lt;/em&gt; the engine applies force to the exhaust gasses and air. This force accelerates the air. To produce thrust $F$, the engine has to impart momentum $p = \frac{F}{t}$ per unit of time on the air. Momentum is proportional to mass and first order of speed. $p = mv$ where $m$ is mass of the gasses (reaction mass) affected by the engine per unit of time and $v$ is speed of those gasses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gasses however also take away some kinetic energy. Kinetic energy is also proportional to mass, but also to &lt;em&gt;second&lt;/em&gt; order of speed. $E_k = \frac12mv^2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This energy has to be provided by the engine. Since the fuel can only provide so much energy (it's heating value) per unit of mass, an engine that needs less energy needs less fuel. And that is achieved by moving more air. Which means higher bypass ratio for jet and bigger propeller for engines with propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that this does not say high-bypass engine would be more efficient at slow speed than at high speed. Because it isn't. All jet engines are more efficient at high speed. This is because the &lt;em&gt;power&lt;/em&gt; the engine produces is $P = Fv$. So at high speed, larger part of the power output is the useful work moving the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In high-bypass engine the maximum power output of the fan is limited though (similar to propeller), so compared to a turbojet the difference in efficiency is higher at low speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-07-28T05:45:43.087" LastActivityDate="2014-07-28T05:45:43.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7915" PostTypeId="1" AcceptedAnswerId="7927" CreationDate="2014-07-28T08:08:12.293" Score="44" ViewCount="20477" Body="&lt;p&gt;I'm sure many people have heard about the communication between a &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2707989/Settle-Captain-Happy-Shocking-audio-revealed-heated-exchange-Delta-pilot-air-traffic-controller.html&quot;&gt;Delta flight 2244 and Atlanta tower&lt;/a&gt; being on news today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the Controller informs the Pilot he is on a wrong taxi-way, things get a little heated up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of who was right who was wrong, there were many lives involved (i'm sure they were not put in danger) but then who takes precedence in such a situation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the controller tell the aircraft to stop dead in its tracks or turn back to the hangar for violating his instructions because there are other planes coming in to land and this can become a little dangerous?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I am fully aware that no one was close to danger and lives were not at risk, but still pilot did worry that there is another plane coming down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was the pilot right in saying &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We'll taxi out there any way we want when you tell us to.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For those who missed. &lt;strong&gt;&lt;a href=&quot;http://www.bizjournals.com/atlanta/morning_call/2014/07/report-delta-looks-into-pilot-s-on-air-rant-with.html&quot;&gt;Here&lt;/a&gt;&lt;/strong&gt; is the whole story&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that this reporting on that article is misleading. It is about taxi clearance and not landing on a wrong runway, However I have no control of what reporters write in their articles. The transcript itself is clear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.liveleak.com/view?i=a08_1406358353&quot;&gt;&lt;strong&gt;Hear the original ATC audio here&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="609" LastEditDate="2015-04-09T14:52:44.647" LastActivityDate="2015-04-09T14:52:44.647" Title="Who has the higher authority, the pilot in command or ATC?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;radio-communications&gt;&lt;taxiing&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7916" PostTypeId="1" CreationDate="2014-07-28T09:30:32.673" Score="6" ViewCount="5176" Body="&lt;p&gt;Are there situations in which a pilot could/has to lower the landing gear during flight for reasons not directly connected to landing? (i.e., not part of the landing checklist)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally I thought I had seen some around the location indicated by the pin on the map below (17° 25' 30.093&quot; N,  78° 32' 27.4734&quot; E), in the evening time around 4:00  and the weather was clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/78nOO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/78nOO.jpg&quot; alt=&quot;Sighting location&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="64" LastEditDate="2014-08-07T14:50:21.337" LastActivityDate="2015-06-18T17:58:48.197" Title="Do some aircraft lower the landing gear mid-flight?" Tags="&lt;approach&gt;&lt;landing-gear&gt;" AnswerCount="7" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7917" PostTypeId="2" ParentId="7915" CreationDate="2014-07-28T09:31:06.747" Score="11" Body="&lt;p&gt;The general rule is: &quot;The pilot in command is ultimately responsible for the flight and its safety&quot;. So if the pilot decided it's better for him to use a certain taxiway due to weight/wingspan or he cannot land on a certain runway, he can make ATC aware and they will try to accommodate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots are expected to follow instructions and clearances of air traffic control under normal operations, unless this would pose a threat to aircraft security or is simply not feasible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATC has the possibility to instruct an aircraft on ground to stop immediately or at the next intersection, etc.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;DAL123, hold position&quot;&lt;br&gt;&#xA;  &quot;DAL123, hold short of Alpha&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the pilot is unable to comply for whatever reason, he must make the air traffic controller aware of this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;DAL123, unable&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ATC has no way of forcing someone to return to the gate, if the pilot does not follow the instructions to return. They could even take off without clearance, but rest assured that they would be met upon arrival at their destination and an investigation opened into why they did not follow instructions. This is also true for using a wrong taxiway, the pilot will be asked to stop and rerouted via the correct taxiways. Mistakes happen, but when instructed to follow a certain set of taxiways, pilots must comply unless unable.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-01-22T08:31:38.460" LastActivityDate="2015-01-22T08:31:38.460" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7919" PostTypeId="1" CreationDate="2014-07-28T09:47:35.663" Score="-5" ViewCount="259" Body="&lt;p&gt;In spite of the strict rules and regulations we see many disasters taking place. Mostly the disaster occurs due to the lapse of one small policy or nature. If the policy is the best then why do crashes still take place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one jet meets a disaster only then other's follow suite regarding their policies(modification or updating it). Is it necessary for a plane to crash for the improvement of the aviation sector can't we hope for a zero crash year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first it's the MH series crashing and now recently one more from Algeria bound plane and later a training helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This year the aviation sector has made several people to think twice before they travel or they might end up in tragedy&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="3012" LastEditDate="2014-07-30T11:32:15.677" LastActivityDate="2014-07-30T11:32:15.677" Title="Isn't it time the aviation sector improve its policies" Tags="&lt;accidents&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2014-07-28T14:52:38.763" ContentLicense="CC BY-SA 3.0" />
  <row Id="7920" PostTypeId="2" ParentId="7916" CreationDate="2014-07-28T10:52:04.923" Score="0" Body="&lt;p&gt;Sure it's a private &lt;strong&gt;&lt;em&gt;jet&lt;/em&gt;&lt;/strong&gt;? Plenty of single-engine piston powered aircraft have fixed landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most jets cruise at high altitudes, so if you can a) see the aircraft, b) identify it as non-commercial, c) notice the landing gear is down, and d) claim that it's not near an airfield then it's more likely that it is a 4-6 seat piston single with fixed gear. Cessna, Piper, Beechcraft have made thousands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Addendum to edited question:&#xA;You say there are no airports &lt;em&gt;near by&lt;/em&gt;. Possible there's one a little further away? Planes typically raise the gear as soon as they are off the runway, but they lower it 30km out. And that's 30km flying distance, not driving diatance.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-07-29T06:43:44.913" LastActivityDate="2014-07-29T06:43:44.913" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7921" PostTypeId="2" ParentId="7916" CreationDate="2014-07-28T12:25:56.650" Score="8" Body="&lt;p&gt;Landing gears are generally retracted to decrease drag in flight . As the speed of &#xA;an aircraft increases, so does parasite drag. Mechanisms to retract and stow the landing gear to eliminate parasite drag add weight to the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Private Jets generally use  Tricycle-type landing gear with dual main wheels . One of the main advantages of using the Tricycle-type landing gear is that it prevents ground-looping of the aircraft. Since the aircraft center of gravity is forward of the main gear, forces acting on the center of gravity tend to keep the aircraft moving forward rather than looping, such as with a tail wheel-type landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not necessary to retract the landing gear . Infact there are Landing gears that are Fixed as can be seen in many small, single engine , light aircrafts . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On certain occasions Private jets as well as large aircrafts like the Boeing 777 extend their landing gear during flight &lt;strong&gt;to cool the Brakes&lt;/strong&gt; because :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;The brakes may have been heated by the previous landing and not had time to cool while the airplane was at the gate&lt;/em&gt;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;During taxi out, they were further heated by necessary brake applications&lt;/em&gt;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;After takeoff, the landing gear retracted into the wheel well where there is limited cooling air&lt;/em&gt;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-07-28T12:25:56.650" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7922" PostTypeId="1" AcceptedAnswerId="7924" CreationDate="2014-07-28T09:06:30.357" Score="40" ViewCount="29486" Body="&lt;p&gt;Two days ago I read in the &lt;a href=&quot;http://www.usatoday.com/story/news/nation/2014/07/25/canada-bomb-threat-flight-panama/13180759/&quot; rel=&quot;noreferrer&quot;&gt;news&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Two U.S. fighter jets escorted a Canada-to-Panama flight back to&#xA;  Toronto after a passenger  allegedly threatened the plane Friday&#xA;  morning. The nature of the threat or why the passenger was agitated&#xA;  were not specified. CBS News  reported that the passenger told a&#xA;  flight attendant, &quot;I have a bomb and I will blow up Canada.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UBEMX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the point of escorting the flight while it has been threatened by a passenger? How do they help to eliminate the threat?&lt;/p&gt;&#xA;" OwnerUserId="1997" OwnerDisplayName="Meysam" LastEditorUserId="1289" LastEditDate="2014-07-29T15:18:23.010" LastActivityDate="2019-02-26T02:55:45.837" Title="What's the point in escorting a threatened flight with two fighter jets?" Tags="&lt;airliner&gt;&lt;military&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7923" PostTypeId="2" ParentId="7922" CreationDate="2014-07-28T09:23:07.367" Score="8" Body="&lt;p&gt;If absolutely necessary the plane can be prevented from making a mess of a major city, but it is basically a rather obvious visible sign to anyone misbehaving in the plane that they are in very, very deep trouble. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the threat of &quot;I have a bomb and I will blow up Canada&quot; the cabin crew are clearly overreacting. Highly unlikely a bomb big enough to take out Canada would go unnoticed, esp. as the plane would be grossly overweight with it.&lt;/p&gt;&#xA;" OwnerDisplayName="Paul" LastActivityDate="2014-07-28T09:23:07.367" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7924" PostTypeId="2" ParentId="7922" CreationDate="2014-07-28T09:23:42.583" Score="36" Body="&lt;p&gt;Fighter jets escorting planes after various sorts of emergencies seems to be standard procedure in many countries, you hear about it quite frequently. It's sometimes implied in the media that if the situation would turn into a 9/11-type hijacking it might be necessary to shoot the plane down but nobody seems willing to fully clarify who could take such a decision and under what conditions on the record.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, in most cases, there isn't even a suggestion that a hijacking is happening but it's difficult to determine that in a timely manner and there are still two things fighters can do in other cases:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Get a visual confirmation of the situation aboard the plane (Is the plane damaged? The cockpit windows obscured? Who is in the cockpit?)&lt;/li&gt;&#xA;&lt;li&gt;“Guide” a pilot who has lost communication to an airport.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, one factor is that being able to scramble jets is often seen as a basic requirement to assert sovereignty (witness the mini-controversy in Switzerland when it was revealed that the air force could not do it at certain times of the day) so politically it seems difficult to entirely give up on it, even if it could be argued that it's a waste of money for smaller countries to maintain an air force that does very little beside this type of missions.&lt;/p&gt;&#xA;" OwnerUserId="3018" OwnerDisplayName="Relaxed" LastEditorUserId="3018" LastEditDate="2015-01-28T15:47:29.673" LastActivityDate="2015-01-28T15:47:29.673" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="7925" PostTypeId="2" ParentId="7922" CreationDate="2014-07-28T12:23:42.890" Score="13" Body="&lt;p&gt;Especially post-911 it became paramount to ensure that such aircraft form no threat to cities and other places where crashing an aircraft into them would cause serious damage.&lt;br/&gt;&#xA;Blowing it out of the sky, however bad it would be for the passengers (not to mention the psychological impact on the fighter crews and their controllers) would be preferable to having thousands of victims on the ground (and a major PR coup for some terrorist group).&lt;br/&gt;&#xA;So jet fighters are scrambled to escort the aircraft until it's on the ground somewhere or the threat otherwise neutralised (say the attempted hijacking foiled by people on board).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;This is little different from fighters being scrambled to escort intruders into a nation's airspace (and in extreme cases shoot them down) which has been done since the end of WW2 and maybe sporadically before (without radar to detect intruders and guide interceptors it's a lot harder to do so obviously, and prior to WW2 that wasn't available).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;In this specific case it may have been overreaction to a madman with a fake bomb, but not knowing whether the threat was real or not it's easier to send up the fighters and later recall them than to have to explain to congress and even worse the press why you didn't act after the jetliner crashes into some city center during lunch hour...&lt;br/&gt;&#xA;Be happy that they have the option to send up fighters and don't have to rely on guided missiles alone, as there's no recalling those once launched...&lt;/p&gt;&#xA;" OwnerUserId="900" OwnerDisplayName="jwenting" LastActivityDate="2014-07-28T12:23:42.890" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7926" PostTypeId="2" ParentId="7919" CreationDate="2014-07-28T14:07:51.447" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;In spite of the strict rules and regulations we see many disasters taking place.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Do we?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the last month or so we've seen several major aircraft accidents/incidents worldwide resulting in loss of hundreds of lives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in that same time we've probably seen tens or hundreds of thousands die from other accidental causes. For example in one small typical western country there are &lt;a href=&quot;http://www.theguardian.com/news/datablog/2011/oct/28/mortality-statistics-causes-death-england-wales-2010&quot; rel=&quot;noreferrer&quot;&gt;17,000 accidental deaths each year&lt;/a&gt; 2,000 deaths from transport accidents and 140,000 deaths from cancer.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; - Cancer                     140000&#xA; - Transport Accidents          2000&#xA; - Air accidents                  20&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.who.int/mediacentre/factsheets/fs310/en/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FQiUD.png&quot; alt=&quot;enter image description here&quot;&gt; W.H.O.&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Look, road injury: 1.3 million deaths each year.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a rational society, this should have some weight in guiding where we ask our governments to spend our money and resources.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is it necessary for a plane to crash for the improvement of the aviation sector&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, to an extent. We the public only pay attention when these things are reported in the mass media, the rest of the time we demand cheap air fares and push out of business any airline that spends much more than the average on safety. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This isn't to argue that we should be complacent, in fact hundreds of people will spend months and years investigating each of those air accidents.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-28T14:19:30.423" LastActivityDate="2014-07-28T14:19:30.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7927" PostTypeId="2" ParentId="7915" CreationDate="2014-07-28T15:28:18.523" Score="72" Body="&lt;p&gt;It isn't a black and white issue of who has higher authority.  A pilot in command (PIC) is the ultimate authority for the safe operation of his airplane.  An air traffic controller is the authority for the block of airspace or pavement he controls.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are operating under ATC, it is your responsibility to comply with their instructions as long as they fall within the regulations, they are safe and you are able to comply,  If ATC issues an instruction contrary to regulation or something that would compromise safety, that is when you exercise your PIC authority to deviate from their instruction.  If you are unable to comply, you exercise your authority to deviate and explain why you are deviating.  When you cannot comply with an ATC instruction, for whatever reason, it is the job of ATC to accommodate your and move other airplanes out of your way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulatory basis for the PIC authority and ability to deviate from ATC instructions is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.1.4.2&quot;&gt;14 CFR 91.3&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.3&lt;/strong&gt;   Responsibility and authority of the pilot in command.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The basis for ATC's authority is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.10#14:2.0.1.3.10.2.4.12&quot;&gt;14 CFR 91.123&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.123&lt;/strong&gt;   Compliance with ATC clearances and instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory. However, except in Class A airspace, a pilot may cancel an IFR flight plan if the operation is being conducted in VFR weather conditions. When a pilot is uncertain of an ATC clearance, that pilot shall immediately request clarification from ATC.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each pilot in command who, in an emergency, or in response to a traffic alert and collision avoidance system resolution advisory, deviates from an ATC clearance or instruction shall notify ATC of that deviation as soon as possible.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Each pilot in command who (though not deviating from a rule of this subpart) is given priority by ATC in an emergency, shall submit a detailed report of that emergency within 48 hours to the manager of that ATC facility, if requested by ATC.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Unless otherwise authorized by ATC, no person operating an aircraft may operate that aircraft according to any clearance or instruction that has been issued to the pilot of another aircraft for radar air traffic control purposes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Absent an emergency, an urgent need* or an inability to comply with ATC, a pilot is required to obey an ATC clearance.  Given this relationship and its exceptions, its is hard to quantify who has a &quot;higher&quot; authority.  Both are the ultimate authorities of their domains, but who overrules who is dependent on the situation.  In general however, ATC will be issuing proper clearances that a pilot is bound by regulation to follow, though the pilot must exercise his authority to execute that instruction in a safe manner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Urgent needs include things like TCAS RA events and things like weather deviations.  In most cases ATC will help you out with a deviation, but if a controller refuses to allow a deviation, I would happily exercise my PIC authority to safely operate my airplane and turn left/right a few degrees rather than penetrate a thunderstorm updraft.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the particular case above, the audio exchange between DL2422 and Atlanta ground is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: Good morning Atlanta ground, delta 2422 approaching 3 South taxi Quebec&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;DL2422 is at the southern exit of ramp 3 and requesting taxi with ATIS information Q.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: Delta 2422, behind the MD88 from your right, runway 27R, taxi via Mike and hold short of Dixie.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ATC has instructed DL2422 to let an MD88 pass from right to left, to taxi on taxiway M to runway 27R but to hold short for taxiway D (in ATL D is &quot;Dixie&quot; due to the larger number of &quot;Delta&quot; airplanes).  To follow this instruction, an airplane should taxi south from spot 3S on taxiway L5, cross L and then turn left on M, then taxi on M, stopping short of D and awaiting further instruction.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: OK behind the 88 from the right, 27R Mike short of Dixie, DL2422&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here, DL2422 acknowledges this correctly.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: DL2422 they won't let you go to Charlotte until 57 minutes after the hour, time now 29 after&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: OK copy 57, DL2422&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;DL2422 has been issued a wheels-up time, but their taxi clearance has not been amended.  They are still cleared to taxi via M short of D.  Sequencing to meet this time will happen east of D in further clearances.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: DL2422, you are supposed to be on M  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: Yes sir, we're going out there right now.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: Looks like you joined L  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: You know what, we'll taxi out there any way we want unless you tell us to, I don't like your attitude.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: I don't have an attitude sir, I'm just saying it looks like you joined L instead of M and I'm just trying to correct you before you stay on L.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: Ok, cause my god, there's another plane out there, its like 6 miles away.  Your attitude is really something sir, we're out here on M. Good morning.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Ground&lt;/strong&gt;: Good morning.  There was no attitude, I was just trying to correct you, that's my job to correct you if you mess up.  I'm just trying to make sure everyone is doing what I ask them for certain reasons.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;DL2422&lt;/strong&gt;: You make a mistake every 2-3 minutes, but my attitude is not like yours, we're out on M and you didn't tell us how to get there so next time you can try doing that.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The DL captain is making a scene and a very roundabout argument that the taxi route did not specify how he was supposed to transition from spot 3S to taxiway M.  I agree that this is the case, but do not understand why any assumption would be made other than to taxi straight out and turn left on M.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a good example of a minor deviation that had DL2422 just turned right and then left and said &quot;oops, fixing that, joining M, thanks!&quot;, then that would have been the end of it.  This captain's unprofessional display will instead net him disciplinary action and classify his deviation as &quot;willful&quot; rather than &quot;accidental&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a clearer visualization of the event, see this image:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1zfor.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1zfor.png&quot; alt=&quot;ATL&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;In this image, the green circle is the starting point of DL2422 and the blue line is the cleared taxi route with the assumed transition to M via L5.  The short red line is the initial taxi route DL2422 took.  It is not clear where they transitioned to M, so I did not extend the red route past the first possible transition.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There appears to be some controversy over the verbiage of &quot;behind&quot; used in the ATC taxi clearance.  The only reference I can find to this word in a cursory search is in FAA order 7110.65 (ATC procedures) in section 3-7-2 that gives example taxi clearances.  This does not define &quot;behind&quot; but does give distinct examples that clearly differentiate &quot;behind&quot; from &quot;follow&quot;.  Given that I cannot find a better reference, all I can offer instead is years of experience in a 121 cockpit based at busy airports like IAH and EWR and plenty of visits to others like ORD, ATL, LAX, DTW, IAD, etc where clearances involving the words &quot;behind&quot; and &quot;follow&quot; are quite common.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Behind&lt;/strong&gt; Use of this word means that you are waiting for an aircraft to pass.  You are giving right of way or yielding to the traffic in question.  This clearance is often given when holding short of an intersection and waiting for perpendicular traffic to cross the intersection before you continue through it.  Much like waiting at a stop sign in a car.  You are not expected to follow the airplane in question and even if you are assigned a turn to taxi along the same route as the airplane, you have your own clearance and are not following that aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Continental 1234 taxi to runway 22R at W via K hold short of S&quot;, followed by &quot;Continental 1234 you'll see a B767 passing right to left on S, behind him continue to runway 22R at W via K R hold short of W&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this case it is quite explicit that an airplane will be passing across your route of taxi and after it passes you are to continue taxiing straight ahead -- not to follow that airplane.  Consider an alternate setup:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Continental 1234 taxi to runway 22R at W via K hold short of S&quot;, followed by &quot;Continental 1234 you'll see a Citation from the right at S, behind him taxi via S W hold short of R.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this case, you are waiting for traffic from the right again, but this time you are turning left after it passes.  You will be taxiing behind it, but you are &lt;em&gt;not&lt;/em&gt; following it.  The Citation has a clearance to taxi S, cross runway 29, to parking.  Your clearance is S turn right on W -- to follow the Citation would be wrong.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Follow&lt;/strong&gt; Use of this word means you are going to fall in behind this airplane and follow it wherever it goes.  You clearance is no longer a specific taxi route, but simply to follow the airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Jetlink 1234, your sequence is the third airbus to your right, the one painted purple.  Follow that airplane to runway 22R at W.  Once behind him, monitor tower, you are number 28 for departure.&quot;, which will be followed by&lt;/li&gt;&#xA;&lt;li&gt;&quot;United 3412, hold short of J, let the EMB-145 get in line then follow him to runway 22R at W.  Monitor tower passing L, you are number 29 for departure&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These clearances are used to get airplanes in line in a specific sequence and simplify giving repeated complex taxi instructions when you can just follow to conga line to the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-07-29T05:06:18.973" LastActivityDate="2014-07-29T05:06:18.973" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="7929" PostTypeId="1" CreationDate="2014-07-28T16:03:12.190" Score="3" ViewCount="933" Body="&lt;p&gt;I tried to work this out.  My thinking is as follows.  If the same amount of energy is given to a low mass particle and a high mass particle, the low mass particle is faster.  A particle with a mass of 1 will be twice as fast as a particle with a mass of 4 but the momentum of the particle with a mass of 1 will be twice that of the particle with mass 2, which seems to go against what is seen with regards to molar mass and specific impulse.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2019-04-08T08:42:07.890" Title="Why do lower molar mass rocket exhaust products give higher specific impulse?" Tags="&lt;fuel&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-07-29T13:15:26.633" ContentLicense="CC BY-SA 3.0" />
  <row Id="7930" PostTypeId="1" CreationDate="2014-07-28T16:15:01.523" Score="6" ViewCount="1493" Body="&lt;p&gt;There is a revolution counter built into the face of the Tachometer in most piston powered GA planes.  This counter is calibrated in hours.  Most planes also have a Hobbs meter, which is a clock.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only at a certain RPM are tach hours equal to clock hours.  This equivalence rpm is different among the various manufacturers and models, and it is published somewhere.  For a Piper Archer II with the standard Lycoming O-360-A4M engine, what is the equivalence RPM, and in what document is it found?  It is not in the Type Certificate Data Sheet (TCDS) for the Archer II (PA-28-181).  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-07-28T16:30:54.633" LastActivityDate="2014-07-28T17:26:30.847" Title="Where to find Tach hour and clock hour equivalence rpm?" Tags="&lt;general-aviation&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7931" PostTypeId="2" ParentId="7930" CreationDate="2014-07-28T17:26:30.847" Score="3" Body="&lt;p&gt;As far as I know the only place to get this information is the tachometer specifications (or at least &lt;a href=&quot;http://www.mitchellproducts.com/tachometers.htm&quot; rel=&quot;nofollow&quot;&gt;I know Mitchell provides it for their tachometers&lt;/a&gt;).&lt;br&gt;&#xA;As you noted, it's not on the TCDS, nor have I ever seen it in the (Piper or Lycoming) maintenance manuals. (It is of course possible I've missed it in the maintenance manuals - they're pretty thick books.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying around in a plane with a working tachometer and don't know the hour-meter's equivalence speed you can always determine it with a watch: every 6 minutes is 0.1 hours, and when the tach is recording at that rate you've found the equivalence RPM.&lt;br&gt;&#xA;(For the Archer I assume it's the same as my Cherokee 180 - around 2300 RPM.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It's worth noting that while you would think the tach's hour meter would be &quot;accurate&quot; (1:1 correspondence) at typical cruise powers that is often &lt;em&gt;not&lt;/em&gt; the case!&lt;br&gt;&#xA;  Using the Archer as an example, 65% power cruise at 7,000 feet is around 2500 RPM, so the tach hour meter will be running slightly faster than 1:1 in a 65% power cruise at 7,000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The watch-check I described above doesn't help you if the reason you need to know this information is your tach has died and you need a replacement - fortunately tachometer manufacturers all know this and publish recommended applications for their tachometers.&lt;br&gt;&#xA;Mitchell lists their &lt;code&gt;D1-112-5023&lt;/code&gt; (2300RPM) tach as the appropriate replacement for the PA28 family, which matches up with the watch-test on my Cherokee.   &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-07-28T17:26:30.847" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7932" PostTypeId="2" ParentId="7929" CreationDate="2014-07-28T18:24:52.527" Score="2" Body="&lt;p&gt;Your question is slightly confusing. What you seem to ask is why, given that momentum is proportional to the energy, and speed increases only with the square of the energy input, a heavy rocket fuel is so much worse than a light fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a rocket, the speed of the burnt gases exiting the nozzle is important. Heavy molecules need more energy for the same acceleration, so the lighter the rocket fuel is, the higher are the nozzle speeds. Momentum is less important, because the mass of the fuel is on both sides of the equation: Heavy fuel in the rocket's tanks needs more energy for the same acceleration, and the chemical energy of the fuel is not proportional to its molecular mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust is mass throughput times exit speed. For a given mass, thrust can be increased if the exit speed can be maximized. Since this mass must be accelerated, the total fuel mass needs to be as small as possible, not the number of fuel molecules (as your question implies). As you say, using lighter molecules helps to achieve this. The only problem is that lighter fuels need more volume, so a hydrogen rocket is bigger than one using alcohol (V-2) or Kerosene (Vostok).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get the best specific impulse, the mixture in a hydrogen rocket engine is not stoichiometric, but uses only as much oxygen as required to heat up the gases up to their dissociation temperature. Adding more oxygen would set free more energy, but this would only be used up to ionize the combustion gases, not to heat them up more (Oberth effect).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="354" LastEditDate="2019-04-08T08:42:07.890" LastActivityDate="2019-04-08T08:42:07.890" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7933" PostTypeId="2" ParentId="3864" CreationDate="2014-07-28T18:51:28.443" Score="9" Body="&lt;p&gt;&lt;strong&gt;NO&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no written record that I have found in researching this question that Langweische ever 'recanted' his beliefs. I cannot source or cite this negative however. I don't actually like this question, since only an answer that he did recant can be sourceable. Any cites showing him supporting his own written beliefs could be disputed by saying &quot;but what about later in life?&quot; This means that a negative answer can only be opinion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not like he left in his LW&amp;amp;T the statement that everything he had written previously was a lie.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2014-07-28T18:51:28.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7934" PostTypeId="1" CreationDate="2014-07-28T19:14:00.547" Score="21" ViewCount="5568" Body="&lt;p&gt;I recently read a story where a pilot of a light aircraft died having attempted to land on a beach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be potentially safer to try an emergency landing on a beach, or go for shallow waters of 6-10 feet depth, or deeper water? (In the absence of anything more suitable).&lt;/p&gt;&#xA;" OwnerUserId="3015" LastEditorUserId="487" LastEditDate="2015-02-27T19:12:32.673" LastActivityDate="2017-08-02T22:52:09.943" Title="What are the risks in landing on a beach vs. shallow waters?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;ditching&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7935" PostTypeId="2" ParentId="7934" CreationDate="2014-07-28T19:51:33.750" Score="5" Body="&lt;p&gt;No difference between &quot;deep&quot; or the 6' - 10' depths you propose.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as landing on the beach, there just are not enough incidents of this happening for anyone to give you a good statistical analysis of actual accidents from which to draw a conclusion.  There are too many variables.  One example: some beaches you can drive a car on, other beaches are so soft the wheels are likely to dig in and cause an abrupt stop or a flip.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-07-28T19:51:33.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7936" PostTypeId="2" ParentId="7934" CreationDate="2014-07-28T20:27:59.383" Score="30" Body="&lt;p&gt;Having done my primary training essentially over beaches I'm pretty well-versed in the &lt;em&gt;theory&lt;/em&gt; (but thankfully not the &lt;em&gt;practice&lt;/em&gt;) of landing on beaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the possible choices offered at your typical beach, the order of preference for landing areas is generally:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Pavement&lt;/strong&gt;&lt;br&gt;&#xA;People like to drive their cars to the beach. There's probably a road or parking lot nearby, and if it's empty enough that's where you want to land.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Dirt&lt;/strong&gt; (&lt;em&gt;not&lt;/em&gt; sand)&lt;br&gt;&#xA;Some beaches have &quot;sandy dirt&quot; areas, usually with low grasses and the like on them. If the beach you're contemplating has such an area it's probably your second-best choice as it will be the firmest ground and closest to landing on a grass strip. (Beware of bumps and rocks!)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Wet&lt;/em&gt; Sand&lt;/strong&gt;&lt;br&gt;&#xA;The sand between the high-water mark and the low-water mark on the beach tends to be fairly compacted, so it can make a decent landing area. It will probably be softer than dirt/grass, but give it your best soft-field technique and you can probably set the plane down without damaging it.&lt;br&gt;&#xA;Properly executed you can put the plane down without doing any substantial damage, and if it's an &lt;em&gt;actual emergency&lt;/em&gt; you're unlikely to get in any trouble.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.nytimes.com/2011/04/06/nyregion/06plane.html?_r=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t4NEw.jpg&quot; alt=&quot;Infamous &amp;quot;Plane lands on NYC beach&amp;quot; photo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Dry&lt;/em&gt; Sand&lt;/strong&gt;&lt;br&gt;&#xA;Fluffy dry sand is a decidedly &lt;em&gt;soft field&lt;/em&gt; situation - soft enough that in a nosewheel aircraft there's a very good chance that no matter how careful you are or how good your soft-field technique is you'll lose one or more of your landing gear - but at least you're on dry land.&lt;br&gt;&#xA;The recent incident in Florida is an example of this: the aircraft's nose gear was sheared off as you can see below, but the pilot and passenger walked away (sadly some bystanders on the ground were injured, and one was killed).&lt;br&gt;&#xA;&lt;a href=&quot;http://www.cbsnews.com/news/small-plane-crash-lands-on-florida-beach-killing-man/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FAcZt.jpg&quot; alt=&quot;Florida beach landing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Water&lt;/strong&gt;&lt;br&gt;&#xA;Unless your plane is on floats water is basically the landing of last resort - particularly for fixed-gear aircraft. The forces involved in putting your wheels into even 6-10 &lt;em&gt;inches&lt;/em&gt; of water are pretty substantial, and there is a real chance of tearing off the gear or losing control of the aircraft in the last few seconds.&lt;br&gt;&#xA;Even if the actual landing is uneventful you will be left to contend with being in the water while evacuating the aircraft which adds complexity to an already difficult situation (and if you're far enough out that the depth of the water is measured in &lt;em&gt;feet&lt;/em&gt; you're going to have to swim back to shore once everyone is out of the aircraft).  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Ditching&quot; an aircraft in the water &lt;a href=&quot;http://www.equipped.org/bschiff-ditching.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;is a subject worth looking into on its own&lt;/a&gt;. Smarter people than I have written &lt;a href=&quot;http://uncontrolledairspace.com/eps/UAHC001.mp3&quot; rel=&quot;nofollow noreferrer&quot;&gt;and spoken&lt;/a&gt; volumes about it, but &lt;a href=&quot;https://aviation.stackexchange.com/a/7935/64&quot;&gt;as Skip Miller pointed out&lt;/a&gt; we don't really have a lot of hard data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-07-28T20:34:21.887" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7937" PostTypeId="1" CreationDate="2014-07-28T20:41:42.727" Score="0" ViewCount="262" Body="&lt;p&gt;Two people provided answers to my previous questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/7845/1289&quot;&gt;What is the nominal frequency of the satellite communications terminal on MH370?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/7867/1289&quot;&gt;How does one interpret the satellite data on flight MH370?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And they referred me to &lt;a href=&quot;http://www.jacc.gov.au/media/releases/2014/june/mr052.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Appendix G&lt;/a&gt;. &quot;Explanatory Notes on BTO and BFO Analysis&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have questions about Appendix G.  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The report (Appendix G) says that the Doppler shift from the satellite (down-link) to GES depends on the satellite movement with respect to GES, since the satellite is not exactly stationary.  But in Table 6. the Down-link Doppler frequency varies, from the satellite to GES depending on the aircraft Latitude. Why should the Aircraft Latitude affect the DeltaFdown Doppler frequency shift?  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;And another question is about the Down-link doppler-shifts, from the Satellite to GES, given in Table 5. The listed Doppler-shift in frequency is -75.1 Hz for UTC time 17:07. However, I can only derive this frequency using the satellite velocity for UTC time 16:55:00?  The calculated frequency differs slightly from the one in the report.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2966" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-07-30T09:38:12.267" Title="Doppler shift in appendix G of ATSB report for the MH370 incident" Tags="&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2014-07-30T02:36:33.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="7938" PostTypeId="2" ParentId="7937" CreationDate="2014-07-28T22:02:49.900" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;1. Why should the Aircraft Latitude affect the Doppler frequency shift?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems to me that table 6 is a check to test whether the equation on page 55 can reliably be used to predict the possible locations of an aircraft from a measured BFO. It does this by using the equation to predict what the BFO should be for a given set of inputs and comparing that with the measured BFO. To see how reliable this is they vary one of the parameters, latitude in this example, to show that the predicted BFO is considerably different for different latitudes and that the best match of predicted BFO to the measured BFO is for the known location of the aircraft. Therefore you know that the BFO is useful - it can be used to rule out some locations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;If you &lt;strong&gt;hold constant all the other factors&lt;/strong&gt; and vary latitude why should that affect BFO?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess it's because for the same aircraft heading (with respect to true north), different latitudes but same headings mean &lt;em&gt;different angles of flight with respect to the satellite&lt;/em&gt;. That means that there are different magnitudes of component of velocity that is parallel to the line from satellite to aircraft - those different magnitudes represent different speeds in a line directly away-from or directly towards the satellite. This affects doppler.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jXDa4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The above doesn't explain why ΔFdown varies with aircraft latitude.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Other independent analyses of this data&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://mh370.bookofresearch.com/Documents/MH370%20data%20analysis%2016-06-2014%20issue%201.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dr Richard E Cole, University College London&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.duncansteel.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dr Duncan Steele&lt;/a&gt; (who asks the same question)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm pretty sure Duncan Steele is smarter than me, so you may be on to something.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;2. However, I can only derive this exact frequency using the satellite velocity for UTC time 16:55:00?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's more of a statement than a question. I guess your question is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;why do my calculations give a different answer?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I see two possibilities&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you made a mistake.&lt;/li&gt;&#xA;&lt;li&gt;the ATSB made a mistake†.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In order for readers to help you with the first or confirm the second, you'd really have to share your calculations with us.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;† And presumably Inmarsat, the NTSB, the AAIB and others.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-30T09:38:12.267" LastActivityDate="2014-07-30T09:38:12.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7939" PostTypeId="2" ParentId="7915" CreationDate="2014-07-28T22:22:15.473" Score="1" Body="&lt;p&gt;It was my experience that the most direct route was understood between the controller and pilot. Consider the ramifications if this were not the case. If another route is needed, it is up to the PIC to inform the controller of that need. Also, if there is ANY question on either side about the instructions or requests, key up the mike and ask! Safe, Orderly, and Expeditious flow of air traffic. &lt;/p&gt;&#xA;" OwnerUserId="3016" LastActivityDate="2014-07-28T22:22:15.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7941" PostTypeId="2" ParentId="7916" CreationDate="2014-07-29T08:03:06.580" Score="22" Body="&lt;p&gt;That's &lt;strong&gt;nowhere near midflight&lt;/strong&gt;. You are seeing aircrafts approaching &lt;a href=&quot;http://ourairports.com/airports/VOHY/&quot; rel=&quot;nofollow&quot;&gt;Begumpet Airport (VOHY)&lt;/a&gt;'s runway 27. This airport has no airline service, but it is used for some general aviation including VIP flights and as military airbase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point directly north (about 3 km) from the coordinates you gave (&lt;a href=&quot;https://www.google.com/maps/place/17%C2%B025&amp;#39;30.0%22N+78%C2%B032&amp;#39;27.0%22E/@17.4532706,78.5342887,13z/data=!4m2!3m1!1s0x0:0x0&quot; rel=&quot;nofollow&quot;&gt;N17° 25' 30&quot;, E78° 32' 27&quot;&lt;/a&gt;) is about 6 km, or 3.2 nm, from threshold of VOHY runway 27. Given usual 3° glide slope the aircraft would be just about 1000 ft above runway elevation, which happens to be the latest point where landing checklist should be complete. Yes, that means gear down. It also means it will be touching down in about a minute and a half.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-18T17:58:48.197" LastActivityDate="2015-06-18T17:58:48.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7943" PostTypeId="1" AcceptedAnswerId="7954" CreationDate="2014-07-29T17:09:21.967" Score="4" ViewCount="19148" Body="&lt;p&gt;Could someone explain the difference between a Continuing Airworthiness Management Exposition CAME and a Continuing Airworthiness Management Organization CAMO?&lt;/p&gt;&#xA;" OwnerUserId="2960" LastEditorUserId="572" LastEditDate="2015-02-19T09:04:33.043" LastActivityDate="2017-05-20T16:57:24.707" Title="What is the difference between CAMO and CAME?" Tags="&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7944" PostTypeId="2" ParentId="7934" CreationDate="2014-07-29T18:58:17.480" Score="4" Body="&lt;p&gt;In a light plane, you definitely want to avoid water unless you are on a plane with floats.  If the wheels are down the when you touchdown in the water there is a high probability of wheels digging in and the plane flipping over nose first.  This type of accident is often not survivable, broken necks, etc.  When I learned to fly amphibians one of the first things you were taught was to verbally repeat &quot;land on land, gear down;  land on water, gear up&quot; before every landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing on smooth damp sand can be like landing on pavement.  You land normally and just ensure you keep you momentum up until you get to your parking spot.  This type of beach landing is pretty common in Mexico.  The hardest part is usually the taxing because you leave the damp sand and end up going into soft dry sand which requires power which throws up sand that abrades the paint on your plane.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-29T18:58:17.480" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7946" PostTypeId="2" ParentId="7626" CreationDate="2014-07-29T23:48:05.360" Score="3" Body="&lt;p&gt;This one goes back a ways, but yes. (early 70s) Center split up a flight of 4 F-4s into 2 flights of 2 over Florida, stacked them over a navaid in the holding pattern. Controller confused the call signs and decended the upper flight of 2 through the 2 holding a thousand feet below. One F-4 lost the vertical stabilizer, both pilots landed safely after a nylon let down. The other F-4 in the mid air lost 6 feet of wing and landed safely engaging the approach end BAK-9 arresting cable. &lt;/p&gt;&#xA;" OwnerUserId="3017" LastActivityDate="2014-07-29T23:48:05.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7947" PostTypeId="1" AcceptedAnswerId="7952" CreationDate="2014-07-30T16:10:12.250" Score="9" ViewCount="3134" Body="&lt;p&gt;&lt;strong&gt;Preface:&lt;/strong&gt; The comments assert the video to have been horizontally flipped, probably because (I am divining) the original belonged to someone else (user 'Jb380' if I remember)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 4 mins 3 secs of &lt;a href=&quot;https://www.youtube.com/watch?v=ryIbpHkeK2U&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt;, the captain (who appears in the video on the right, but per the preface above, should be on the left) pushes forward the throttle, but from which he then removes his hand to use this same hand to push a button that changes an instrument display,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;from showing the tail view (camera) of the aircraft (to assist with taxiing???),&lt;/li&gt;&#xA;&lt;li&gt;to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Primary_flight_display&quot; rel=&quot;nofollow noreferrer&quot;&gt;primary flight display&lt;/a&gt;.    &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Afterward he replaces this hand back atop the throttle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why doesn't he instead push the button before deciding to takeoff and set takeoff thrust: this is safer than the above? For example, if abortion is decided exactly when nobody's hand is handling the throttle, then previous seconds needed to stop would be wasted?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="128" LastEditDate="2017-08-09T02:18:31.267" LastActivityDate="2017-08-09T07:27:52.707" Title="During takeoff, why throttle forward then raise hand from throttle to push a button, instead of pushing button then throttling?" Tags="&lt;takeoff&gt;&lt;throttle&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7948" PostTypeId="2" ParentId="7947" CreationDate="2014-07-30T18:09:29.317" Score="3" Body="&lt;p&gt;This is completely normal in Aircrafts like the A380 , Boieing 777 etc . Hands off at V1 (Engine failure recognition speed) is perfectly proper in an aircraft with multiple engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The throttles still moves , however the power setting (EPR) is in the computer and the precise setting of the engines is automated. The Pilot Flying the aircraft will still feel the throttles vibrating under his hand, but it's the auto throttle doing it, and not the  flight engineer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If Auto thrust is engaged, then there are 3 detents - Climb, Max Continuous/Flex and TOGA. &#xA;If Autothrust is not engaged (at any time in the flight) then the thrust levers work just like the T/Ls on any other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During take off, the T/Ls are placed either in TOGA (Take Off/Go Around) if  the pilot is doing a max power T/O, or in Flex/Max Continuous detent if the pilot is doing a Flex power T/O. When the levers are in either of these detents the FADEC (Full authority digital engine control) will give  the aircraft  the max power available for that selection (It depends on the ambient conditions). When the aircraft  reach the Thrust Reduction altitude the pilot may choose to  move the levers backwards to the Climb detent, and will then get Climb power. The levers remain in this detent until the pilot reduces thrust to idle in the flare during the landing . This means that the FADEC will give the aircraft whatever power is necessary to achieve what you are trying to do - climb power for the climb, or whatever thrust is necessary to achieve your cruising Mach number, or desired rate of descent or whatever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine fails, then the levers on the remaining engines are moved back into the Flex/Max Continuous detent, and the aircraft will get Max Continuous power. If the pilot has to do a go-around at the destination, the pilot puts the levers into the TOGA detent and the aircraft will get all the power available.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-07-30T18:09:29.317" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="7949" PostTypeId="2" ParentId="7626" CreationDate="2014-07-30T19:05:55.877" Score="2" Body="&lt;p&gt;Sure.  I have been given an incorrect heading to fly that could have been tragic (fly into mountain or another aircraft).  Just like pilots, controllers can lose Situation Awareness.  Especially given their schedules that have them working crazy shift with minimal down/sleep time.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-07-30T19:05:55.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7950" PostTypeId="2" ParentId="7916" CreationDate="2014-07-30T20:39:22.343" Score="1" Body="&lt;p&gt;I cannot imagine much need to lower the gear during flight, except perhaps if there was an issue.  Also doing so mid flight would required restricting speed to the lower of Vlo (landing gear operating speed) or Vle (landing gear extended speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actions that one takes that involve dropping the gear are usually part of some error handling procedure.  These may be documented in operational manual or be something defined during training on the specific aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one time I dropped gear in flight it was after one of the gear lights failed to turn off (indicating gear up and stowed) after retract.  I slowed up to stay within the operational limits, dropped the gear and then retracted the gear.  This time the gear light stayed off.  After landing I checked the gear switches for a stuck piston or loose wire.  I did not find anything and the problem never repeated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the problem had been something like a gear motor circuit breaker popping I would have reset the breaker ONCE.  If the breaker popped again I would have cranked the gear down and left it down.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-07-31T15:46:30.217" LastActivityDate="2014-07-31T15:46:30.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7952" PostTypeId="2" ParentId="7947" CreationDate="2014-07-30T21:00:47.053" Score="13" Body="&lt;p&gt;Actually he &lt;em&gt;does&lt;/em&gt; push the button before selecting &lt;em&gt;takeoff&lt;/em&gt; thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often&lt;sup&gt;1&lt;/sup&gt; the procedure on jets during take-off is to move the thrust levers about half way, wait for the engines to spool up and only then select TO/GA or Flex thrust as desired. In the video the pilot switches the display during this intermediate step. So the engines are not even spooled up yet and the aircraft is still moving slow. Plenty of time to stop if anything fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact even when nearing v₁ the reaction does not need to be &lt;em&gt;that&lt;/em&gt; fast. The calculation of v₁ includes 2 s reaction time and &lt;em&gt;correct&lt;/em&gt; response is more important. Look e.g. on &lt;a href=&quot;http://www.youtube.com/watch?v=J-LSNsTIVLM&quot;&gt;this training video&lt;/a&gt; (it's A330, not A380, but the procedure is the same). The reaction is not &lt;em&gt;that&lt;/em&gt; fast; they only retard the throttle after checking and calling the fault (&quot;engine fire&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;It used to be that the engines could flame out if you added fuel too quickly, but that's no longer the case now when engines are managed by FADEC (full authority digital engine computer). Some manufacturers/airlines/pilots maintain the procedure, most likely to avoid applying full power if one of the engines manifests some problem early. Or at least the pilot in &lt;em&gt;this&lt;/em&gt; video does it.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-07-31T08:21:59.190" LastActivityDate="2014-07-31T08:21:59.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7953" PostTypeId="2" ParentId="3297" CreationDate="2014-07-31T02:22:33.550" Score="11" Body="&lt;p&gt;Others have said that a telescope suitable for astronomy would be overpowered for viewing aircraft, but this isn't true.  Manually keeping aircraft in the field of view would be difficult, but you can use software to automatically steer a computer-controlled telescope and get great results.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, here's a photo of an aircraft being tracked by the tracking application &lt;a href=&quot;http://www.optictracker.com/&quot; rel=&quot;noreferrer&quot;&gt;OpticTracker&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dwIQi.jpg&quot; alt=&quot;Aircraft being tracked by telescope&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=fbz7jD5RAWI&quot; rel=&quot;noreferrer&quot;&gt;demo video&lt;/a&gt; shows both a Meade LX200 and a Celestron NexStar 4E being used with OpticTracker to track various aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other tracking applications out there; OpticTracker is just one I've researched. In order to select an appropriate telescope, I would start with the requirements for whatever tracking software you're considering using.  For example, you can see the list of telescopes compatible with OpticTracker on the &lt;a href=&quot;http://www.optictracker.com/Compatibility.html&quot; rel=&quot;noreferrer&quot;&gt;compatibility page&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3037" LastActivityDate="2014-07-31T02:22:33.550" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7954" PostTypeId="2" ParentId="7943" CreationDate="2014-07-31T07:51:04.387" Score="3" Body="&lt;p&gt;CAMO is the organisation and CAME is a &quot;book&quot; that need to write.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &quot;book&quot; contain procedure to explain how you will work (how you communicate with aircraft customers, how you manage your docs, etc...).&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="595" LastEditDate="2017-05-20T16:57:24.707" LastActivityDate="2017-05-20T16:57:24.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7955" PostTypeId="1" AcceptedAnswerId="7960" CreationDate="2014-07-31T07:56:23.400" Score="64" ViewCount="62579" Body="&lt;p&gt;What are the pods with the sharp trailing edges underneath the wings of large airliners, as shown in the image below?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/kjH0J.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My best guess would be fuel tanks&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="19" LastEditDate="2015-02-23T13:04:11.020" LastActivityDate="2017-10-20T15:38:27.520" Title="What is the purpose of the sharp pods under airliner wings?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="7956" PostTypeId="1" AcceptedAnswerId="7958" CreationDate="2014-07-31T07:59:59.837" Score="5" ViewCount="6883" Body="&lt;p&gt;I recently watched a video of the Boeing 787 training before Farnborough.  This aircraft climbed very fast; does someone know the maximum pitch of this aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="10076" LastEditDate="2020-06-14T13:17:12.390" LastActivityDate="2020-06-14T13:17:12.390" Title="What is the maximum pitch for the Boeing 787 Dreamliner?" Tags="&lt;boeing&gt;&lt;boeing-787&gt;&lt;pitch&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="7957" PostTypeId="2" ParentId="7955" CreationDate="2014-07-31T08:24:19.013" Score="24" Body="&lt;p&gt;They are not fuel tanks, the fuel tanks are inside the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those are covers for the flaps actuators: since the actuators and their rails protrude beneath the wing, without a cover they would greatly increase drag. The covers are more aerodynamic and thus produce overall less drag (at the expense of a slight increase in overall weight)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://en.wikipedia.org/wiki/Anti-shock_body&quot;&gt;Anti-shock bodies&lt;/a&gt; for more information and pictures.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-07-31T08:35:22.987" LastActivityDate="2014-07-31T08:35:22.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7958" PostTypeId="2" ParentId="7956" CreationDate="2014-07-31T09:30:08.553" Score="8" Body="&lt;h2&gt;30 degrees.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Boeing aircraft, including the 787, have a Pitch Limit Indicator (PLI) in the flight display that tells the pilot how far the wing's angle of attack (AOA) is from stall.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the PLI also is limited to 30 deg of pitch attitude, regardless of AOA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But it depends on aircraft configuration&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During takeoff climb, there is no single target AOA to fly that will guarantee certified takeoff performance. Takeoff-climb AOA will vary with such factors as airplane gross weight, thrust, altitude, flap setting, and CG. Takeoff-climb speeds (hence, AOA) are limited by stall speed, tail clearance, and minimum control speeds. The higher speed and greater thrust of an all-engine takeoff reduce the AOA significantly relative to an engine-out takeoff at the engine-out climb speed (V2 ).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html&quot; rel=&quot;noreferrer&quot;&gt;Boeing &lt;em&gt;Aero&lt;/em&gt; No.12&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;At Farnborough 2014, pilots Neville and Bryan were pulling stunts that would get airline pilots fired. Most airlines limit pitch to 20 degrees (or in a few cases 25) from what I've read.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;They kicked off the demonstration with a spectacularly steep takeoff, pitching the plane up &lt;strong&gt;just shy of 30 degrees&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'd guess they flew just inside what Boeing consider unsafe for those conditions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boeing won’t reveal ... just how steeply it can take off&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.wired.com/2014/07/watch-test-pilots-push-the-new-boeing-jet-to-terrifying-limits/&quot; rel=&quot;noreferrer&quot;&gt;Wired - &quot;terrifying&quot;&lt;/a&gt; (my emphasis). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think we can be reasonably confident that no production 787 will ever, after take-off, initially climb at greater than 30 degrees.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Flight envelopes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The way I understand it, asking about the &quot;maximum&quot; of anything for an aircraft is less useful than understanding the flight envelope. This is because the maximum depends very greatly on the exact situation of the aircraft including things like altitude, weight, speed etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airinformatics.com/787_FT_Summary.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rcBhK.jpg&quot; alt=&quot;787 flight envelope&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Actual flight data from the six Boeing 787 test aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-07-31T13:50:31.803" LastActivityDate="2014-07-31T13:50:31.803" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7959" PostTypeId="1" AcceptedAnswerId="7961" CreationDate="2014-07-31T10:31:03.760" Score="5" ViewCount="4357" Body="&lt;p&gt;I hope I am at the right place here. Asking this at Stackoverflow is not allowed (off topic)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to be able to plan flights in the future. (6-12 months ahead) I only know the &lt;code&gt;Flights ID&lt;/code&gt; like &lt;code&gt;LH2014&lt;/code&gt;. All I want is to get the departure/arrival airport and times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you know of any API or fresh database?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I am booking a flight 6 months in advance I will get all the information. So it should be possible. Or is this the data from the day I booked the flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried few APIs like flightaware or flightstats, but they can only deliver data for max. 72 hours in advance, not 6 months.&lt;/p&gt;&#xA;" OwnerUserId="3040" LastEditorUserId="247" LastEditDate="2014-08-01T10:29:37.097" LastActivityDate="2014-08-01T10:29:37.097" Title="Is there a Flights API to get flight information months in advance?" Tags="&lt;flight-schedules&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7960" PostTypeId="2" ParentId="7955" CreationDate="2014-07-31T12:33:27.573" Score="73" Body="&lt;p&gt;They are &lt;a href=&quot;http://en.wikipedia.org/wiki/Anti-shock_body&quot; rel=&quot;noreferrer&quot;&gt;Anti-shock bodies&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the transsonic speed range (above about Mach 0.7), aircraft drag is governed by &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;noreferrer&quot;&gt;Whitcomb area rule&lt;/a&gt;, which basically says that to minimize drag, the aircraft cross-sectional area must change as smoothly as possible, independent of its actual shape. It is somewhat counter-intuitive, but well established.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this Junkers patent drawing (via Wikipedia):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Area_rule#mediaviewer/File:Patent_932410_Seite_5.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/2/28/Patent_932410_Seite_5.gif/220px-Patent_932410_Seite_5.gif&quot; alt=&quot;Junkers patent drawing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which shows various combinations of positioning engines to adopt the area rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the usual aircraft design the cross-section increases over the engines that hang ahead of the wing leading edge and then the thick part of the wing and wing box (the thicker part of fuselage where wings connect), but the wing tips are too thin and the cross-sectional area would decrease too quickly, so something needs to be attached to the trailing edge to make the reduction of cross-sectional area smoother. The anti-shock bodies are usually conveniently combined with flap actuator and track fairings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are however &lt;em&gt;some&lt;/em&gt; aircraft that have anti-shock bodies combined with other functions, e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Tu-134&quot; rel=&quot;noreferrer&quot;&gt;Tu-134&lt;/a&gt; (and many other designs by Tupolev Design Bureau) retracts landing gear in its anti-shock bodies (which are just one large on each side):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Tu-134#mediaviewer/File:MAGAS_Kosmos_Tupolev_Tu-134_Misko.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e9/MAGAS_Kosmos_Tupolev_Tu-134_Misko.jpg/640px-MAGAS_Kosmos_Tupolev_Tu-134_Misko.jpg&quot; alt=&quot;Tu-134&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flap actuator and track fairings exist on all aircraft that have flaps that extend aft as well as down (&lt;a href=&quot;http://en.wikipedia.org/wiki/Fowler_flap#Fowler_flap&quot; rel=&quot;noreferrer&quot;&gt;Fowler flaps&lt;/a&gt; and their double-slotted variants), but on slower planes they are much thinner. Compare e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/ATR-72&quot; rel=&quot;noreferrer&quot;&gt;ATR-72&lt;/a&gt;, which does not need to be area-ruled with its maximum Mach 0.55.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/ATR-72#mediaviewer/File:Aer_Arann_ATR-72_EI-REE_Bristol.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Aer_Arann_ATR-72_EI-REE_Bristol.jpg/640px-Aer_Arann_ATR-72_EI-REE_Bristol.jpg&quot; alt=&quot;ATR-72&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.163" LastActivityDate="2014-08-01T15:50:14.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7961" PostTypeId="2" ParentId="7959" CreationDate="2014-07-31T18:46:03.017" Score="5" Body="&lt;p&gt;A similar question was asked on Stack Overflow: &lt;a href=&quot;https://stackoverflow.com/a/2899086/178673&quot;&gt;https://stackoverflow.com/a/2899086/178673&lt;/a&gt; (and marked off-topic, but it did have some answers)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are booking a flight, you are typically providing more information than just the flight number, in fact, the query is usually &quot;here is my date/time and arrival/departure information, what is available?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are providing the departure date (or range) and arrival date (or range), as well as the city-pairs, and when you have that data you can use the API from FlightStats to find out the list of flights: &lt;a href=&quot;https://developer.flightstats.com/api-docs/scheduledFlights/v1&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://developer.flightstats.com/api-docs/scheduledFlights/v1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you just knew the flight number, you could use the API call for &quot;Scheduled Flight(s) by carrier and flight number, departing on the given date. &lt;code&gt;/v1/json/flight/{carrier}/{flightnumber}/departing/{year}/{month}/{day}&lt;/code&gt;, but again, you still need something to put in as either the departing or arrival date.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Programmatically, perhaps if it didn't return a hit for the date you specified, you could search on &lt;code&gt;x&lt;/code&gt; days of either side of the date.  For example, October 19, 2014 didn't return a hit for LH2014 (I know this is a daily, Monday-Friday flight), and the API would return that it didn't hit, so then we (arbitrarily in this example) check two days on either side &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Psuedo-code example: &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;day = 19&#xA;/v1/json/flight/LH/2014/departing/2014/10/{day-2}&#xA;/v1/json/flight/LH/2014/departing/2014/10/{day-1}&#xA;/v1/json/flight/LH/2014/departing/2014/10/{day+1}&#xA;/v1/json/flight/LH/2014/departing/2014/10/{day+2}&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;And find out that it is scheduled on the 17, 20 and 21 of October and that it flies MUC-DUS, in an A319/20.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the API isn't going to do all the work for you, but you could probably wrangle the API to give you the information you want in a format you want.  With some built-up logic around the question you're really trying to ask and multiple API calls (Is this flight number available on this date and what are the city-pairs, and if it's not available what date(s) is it available?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this is helpful. :)&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="-1" LastEditDate="2017-05-23T12:41:54.650" LastActivityDate="2014-07-31T18:52:38.787" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7962" PostTypeId="1" CreationDate="2014-07-31T19:39:51.303" Score="10" ViewCount="1564" Body="&lt;p&gt;I contacted a flight briefer this morning in the San Francisco Bay Area in California. At the time, ceilings at my airport (Palo Alto) had just hit 1000 ft, so the field was (barely) VFR. It is a very common pattern in this area for the ceiling to burn off, become broken, scattered, and then disappear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The briefer told me there was an Airmet Sierra for IFR conditions and mountain obscuration in force, and that VFR flight was not recommended. When I talked with an instructor at the club, we talked about the specific location of the clouds and decided the whole area would soon be VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question: should I fly if conditions are clearly VFR but the flight briefer is telling me “VFR flight not recommended”? How should I think through the risk assessment here?&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="572" LastEditDate="2015-02-27T06:53:15.723" LastActivityDate="2019-10-02T10:23:36.240" Title="Should I fly if conditions are VFR but the flight briefer says &quot;VFR Flight Not Recommended&quot;?" Tags="&lt;faa-regulations&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7963" PostTypeId="2" ParentId="7962" CreationDate="2014-07-31T19:52:48.550" Score="6" Body="&lt;p&gt;Quoting &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0701.html&quot;&gt;AIM 7-1-4&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2. VFR Flight Not Recommended. When VFR flight is proposed and sky conditions or visibilities are present or forecast, surface or aloft, that, in the briefer's judgment, would make flight under VFR doubtful, the briefer will describe the conditions, describe the affected locations, and use the phrase &quot;VFR flight not recommended.&quot; This recommendation is advisory in nature. The final decision as to whether the flight can be conducted safely rests solely with the pilot. Upon receiving a &quot;VFR flight not recommended&quot; statement, the non-IFR rated pilot will need to make a &quot;go or no go&quot; decision. This decision should be based on weighing the current and forecast weather conditions against the pilot's experience and ratings. The aircraft's equipment, capabilities and limitations should also be considered.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="639" LastActivityDate="2014-07-31T19:52:48.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7964" PostTypeId="2" ParentId="7962" CreationDate="2014-07-31T21:17:48.833" Score="13" Body="&lt;p&gt;&quot;VFR Flight Not Recommended&quot; is a judgement call made by the flight briefer. It means, &lt;a href=&quot;https://aviation.stackexchange.com/a/7963/64&quot;&gt;as you noted from the AIM&lt;/a&gt;, that the briefer doesn't think flying around VFR is a smart idea based on what they're seeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual reasons for a briefer using this phrase are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The weather is currently below VFR minimums somewhere along your intended route.&lt;/li&gt;&#xA;&lt;li&gt;The weather is currently &quot;Marginal VFR&quot; somewhere along your intended route.&lt;/li&gt;&#xA;&lt;li&gt;The weather is &lt;em&gt;forecast to be&lt;/em&gt; marginal VFR or below somewhere along your intended route.&lt;/li&gt;&#xA;&lt;li&gt;Some other adverse condition (like mountain obscuration) exists along your route or in the area you intend to fly.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The briefer's recommendation is just that: &lt;em&gt;a recommendation&lt;/em&gt; -- it is not binding. How you evaluate the flight to make a Go/No-Go decision when the briefer provides this recommendation is your choice as pilot in command. You will need to consider &lt;em&gt;why&lt;/em&gt; the briefer is telling you VFR flight is not recommended, and apply your own knowledge and judgment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple of examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the briefer is telling you this because Airmet Sierra is active for mountain obscuration and you intend to fly through some mountain passes prudence suggests that proceeding VFR into mountains that may be obscured by clouds would be a &lt;em&gt;Bad Idea&lt;/em&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the briefer is telling you this because the weather is currently marginal VFR, but it's forecast to improve and you only plan to shoot a few touch-and-go landings at your home airport you might proceed with the flight anyway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For evaluating the huge swath of conditions in between those two extremes consider your familiarity with the area (typical weather patterns, topography, obstacles, etc.) and the conditions of flight (especially day-vs-night). Thomas P. Turner's site has a &lt;a href=&quot;http://www.thomaspturner.net/Categorical%20outlook%20matrix.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;nice set of guidelines&lt;/a&gt; which I happen to broadly agree with, but each flight needs to be carefully evaluated to determine if you believe you can complete it safely under the conditions reported to you by the briefer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The safest approach is obviously to cancel the flight (or complete it under instrument flight rules) if you have any doubt.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-08-01T18:30:28.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7965" PostTypeId="2" ParentId="7916" CreationDate="2014-07-31T23:41:06.253" Score="9" Body="&lt;p&gt;Yes. If you want to increase drag to lose altitude quickly. For example, mountain flying, need to descend rapidly and speed brakes + flaps just aren't cutting it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fun fact: The F4U Corsair used its landing gear as speed brakes. There was a special way they lowered them in this case. (I belive the hydraulic struts weren't locked ect., so landing on them would not be smart)&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2014-07-31T23:41:06.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7966" PostTypeId="2" ParentId="7815" CreationDate="2014-08-01T00:00:07.643" Score="2" Body="&lt;p&gt;Because the engines in some of these aircraft are more powerful than needed. Remember, 250 airspeed rule below 10k feet. If an aircraft is cleared to &quot;after takeoff climb and maintain 2000&quot; then he wont need all of this power. Additionally, the aircraft isn't fighting drag from gear/flaps at this point, nor friction on the ground. And it is no longer a race to get off the runway. Why not save fuel AND avoid a stern talking to from the FAA at the same time? Once the aircraft is cleared to a higher altitude, they spool up again for the climb.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2014-08-01T00:00:07.643" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7967" PostTypeId="1" AcceptedAnswerId="7968" CreationDate="2014-08-01T01:37:17.557" Score="32" ViewCount="7350" Body="&lt;p&gt;How are anti-aircraft missiles and counter-measures tested?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When they design an anti-aircraft missile, how do they test it so that it actually locks on to a target and destroys it? Do they simply fly a plane in the air and then fire a missile at it and have the pilot eject?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarily, how are counter-measures tested? Do they fire a missile at a target and check whether it misses?&lt;/p&gt;&#xA;" OwnerUserId="3049" LastEditorUserId="15311" LastEditDate="2018-06-04T18:08:47.927" LastActivityDate="2018-06-04T18:08:47.927" Title="How are anti-aircraft missiles tested?" Tags="&lt;military&gt;&lt;missiles&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7968" PostTypeId="2" ParentId="7967" CreationDate="2014-08-01T03:00:57.933" Score="42" Body="&lt;p&gt;The short answer is that the final qualification tests are done against drones like the &lt;a href=&quot;http://www.fencecheck.com/content/index.php?title=The_Final_Mission:_The_USAF%92s_QF-4_Target_Drones&quot;&gt;QF-4&lt;/a&gt;, which are converted from retired F-4 fighters.  These tests are still extremely expensive, into the millions per aircraft destroyed, so there are many dry runs and non-destructive tests completed beforehand.  Sacrificing a target drone isn't done until the project team is very confident of a positive result or they are unable to obtain necessary data by other means.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2014-08-01T03:00:57.933" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="7969" PostTypeId="2" ParentId="7967" CreationDate="2014-08-01T07:47:55.197" Score="25" Body="&lt;p&gt;A large part of the complexity of any missile is in propulsion and guidance. The warhead isn't trivial, but in comparison that's not the hardest part. This means that in testing, you can often replace the warhead with a sensor package. This applies both to missile development and counter-missile development.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Missile warheads additionally can be tested on test stands, without being launched first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This just leaves an integration test where missile and warhead are tested in combination, and for that Brian's answer applies. &lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2014-08-01T07:47:55.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7970" PostTypeId="2" ParentId="7886" CreationDate="2014-08-01T08:37:46.510" Score="2" Body="&lt;p&gt;I have 5,000+ hours of tail-wheel experience. So, heres my two cents:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I won't elaborate on the physics of what's happening since voretaq7 explained that topic pretty well (thankfully). I will concentrate on a more practical understanding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;How difficult is it to avoid ground loop in practice?&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not difficult, you just keep the plane straight...at all times, no matter what it takes. I would say your simulator isn't very accurate in portraying real-life tail-dragger characteristics. I have never flown a Pitts, however of the other tail-draggers I have flown, they are not extremely difficult to keep straight, just attention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;what would likely be wrong with model that is too difficult to control?&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One where the aircraft does not have enough rudder-authority to compensate for either:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The current wind velocity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The amount of torque the engine produces.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A combination of 1 and 2.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;These characteristics seem to be more per-dominate by the design of an aircraft as well. (short-coupled and narrow-wheelbase aircraft being in that group). I do not know much about physics, so I can't elaborate on the why, other than I know from experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find that once the tail is up and flying, it is &lt;strong&gt;EASIER&lt;/strong&gt; to keep the airplane straight, you have more rudder authority (i.e. control) of the aircraft to main directional control, but that may be just me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, flying a tail-dragger is not all that difficult, it sounds like your simulator does a poor-job giving tail-dragger flight characteristics. With that said, I also find simulators to feel very un-natural. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as flying a real tail-dragger. It takes a bit getting used, but it's like anything else. Once you get the hang of it, your good to go.&lt;/p&gt;&#xA;" OwnerUserId="553" LastActivityDate="2014-08-01T08:37:46.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7971" PostTypeId="1" AcceptedAnswerId="7975" CreationDate="2014-08-01T15:28:34.283" Score="5" ViewCount="1710" Body="&lt;p&gt;Is there any accurate model that can take flight data, plane identifications and compute the amount of fuel that the aircraft would burn flying a set route over the Atlantic ocean.&lt;/p&gt;&#xA;" OwnerUserId="3053" LastEditorUserId="167" LastEditDate="2015-02-21T13:28:38.107" LastActivityDate="2015-02-21T13:28:38.107" Title="Is there a model to calculate fuel burn over the Atlantic ocean given an arbitrary aircraft identification?" Tags="&lt;jet&gt;&lt;oceanic&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7972" PostTypeId="1" CreationDate="2014-08-01T17:00:51.970" Score="5" ViewCount="432" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Ve5w.jpg&quot; alt=&quot;Image of document detailing handling services and facilities. One of the sections of the document refers to aircraft with maximum takeoff weight of &amp;gt;45,000 T&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I got the &lt;a href=&quot;http://www.aisthai.aviation.go.th/webais/pdf/AD%20vol1/AD2_1VTBD.pdf#page=2&quot; rel=&quot;nofollow noreferrer&quot;&gt;attached document&lt;/a&gt; from &lt;a href=&quot;http://www.aisthai.aviation.go.th/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.aisthai.aviation.go.th/&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This document refers to aircraft with MTOW 45000T.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is that 45000 tons? That's pretty heavy for me. Or am I interpreting the document incorrectly?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="167" LastEditDate="2015-02-21T13:37:24.640" LastActivityDate="2016-02-22T22:33:09.897" Title="I have a document referring to aircraft with maximum takeoff weight of 45000T. Is this an error?" Tags="&lt;ground-operations&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7973" PostTypeId="2" ParentId="7967" CreationDate="2014-08-01T17:25:38.070" Score="8" Body="&lt;p&gt;They also conduct many tests using towed dummy units. (TDUs)  These will often be small in physical size but have radar reflection or heat generation to allow it to look like a normal aircraft to the missile.  Much less expensive to destroy.  The missile will also have a failsafe using the IFF technology so that it does not attack the towing aircraft, and an additional failsafe that the missile can be destroyed manually.&lt;/p&gt;&#xA;" OwnerUserId="3055" LastEditorUserId="1467" LastEditDate="2014-08-01T17:36:40.727" LastActivityDate="2014-08-01T17:36:40.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7974" PostTypeId="2" ParentId="7972" CreationDate="2014-08-01T17:40:58.987" Score="4" Body="&lt;p&gt;That is not &lt;code&gt;45000&lt;/code&gt; but &lt;code&gt;45,000&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeing that the comma has been used for thousands in the fuel trucks capacity, it could be a copy-pasted typo.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-08-01T17:40:58.987" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="7975" PostTypeId="2" ParentId="7971" CreationDate="2014-08-01T20:54:10.553" Score="9" Body="&lt;p&gt;I am sure every airline has such a model, which will include actual wind and temperature information, but it will contain proprietary data which is not publicly available, unless you have a proven interest and signed an NDA with the airframe and the engine companies. Boeing is actively marketing &lt;a href=&quot;http://www.boeing.com/boeing/commercial/aviationservices/flight-services/flight-operations/airplane-performance-tools.page&quot;&gt;such software&lt;/a&gt; to it's customers. For first-order estimates, Federico's comment is a good start, but you will still need fuel flow and L/D values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A range of similar software exists, but here the quality of the output depends mainly on the quality of the aircraft and engine models. While Boeing should know their aircraft well, the authors of independent software like &lt;a href=&quot;http://www.piano.aero&quot;&gt;Piano&lt;/a&gt; or &lt;a href=&quot;http://www.darcorp.com/Software/APP/&quot;&gt;APP&lt;/a&gt; have to guess the right values, but still sometimes such tools will be precise within one percent. Piano even offers a free version called Piano X, but you will need to burden yourself with a Windows installation to run it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need even more precision, there are commercial packages which do this, first of all &lt;a href=&quot;http://www.j2aircraft.com&quot;&gt;J2 Aircraft Dynamics&lt;/a&gt;. But this does much more; fuel flow is only a tiny aspect of the full package. Eurocontrol is supporting &lt;a href=&quot;https://www.eurocontrol.int/services/bada&quot;&gt;BADA&lt;/a&gt;, which is a tool for computing aircraft trajectories, but it can also compute the full flight and contains an extensive set of detailed aircraft datasets. Access to BADA is restricted, however, and you will need to acquire a license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to assemble your own tool, &lt;a href=&quot;http://jsbsim.sourceforge.net/index.html&quot;&gt;JBSim&lt;/a&gt; would be a good start. Write a wrapper which calls JBSim repeatedly and keeps track of the aircraft trajectory, and integrates the flight parameters along the way. But you will still need to get the aerodynamics and engine data from somewhere.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-08-01T20:54:10.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7976" PostTypeId="1" CreationDate="2014-08-01T20:59:27.467" Score="0" ViewCount="1665" Body="&lt;p&gt;I was wondering as to the measurements of  &quot;black box&quot; recorders. I have a new invention involving the &quot;Black Box&quot; and I need to know the measurements of the recorder.&lt;/p&gt;&#xA;" OwnerUserId="3057" LastActivityDate="2014-08-01T22:10:55.917" Title="What are the measurements for a &quot;Black Box&quot;?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-08-01T22:07:12.287" ContentLicense="CC BY-SA 3.0" />
  <row Id="7977" PostTypeId="2" ParentId="7976" CreationDate="2014-08-01T21:13:10.107" Score="6" Body="&lt;p&gt;The two main &quot;black boxes&quot; are the Flight Data Recorder (FDR) and the Cockpit Voice Recorder (CVR). These units are available from various manufacturers and therefore sizes vary. Many units can be used as either CVR or FDR, or as both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A quick search provides a few examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;etep &lt;a href=&quot;http://www.etep.com/products/product.php?ID=29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sentinel ED-112&lt;/a&gt;: CVR/FDR&lt;/strong&gt;&lt;br&gt;&#xA;Height: 3.929 in (9.980 cm)&lt;br&gt;&#xA;Width: 4.970 in (12.624 cm)&lt;br&gt;&#xA;Depth: 6.907 in (17.545 cm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;L3 &lt;a href=&quot;http://www.sea-avionics.com/lc/cart.php?target=productDetails&amp;amp;model=F1000&amp;amp;substring=&quot; rel=&quot;nofollow noreferrer&quot;&gt;F1000&lt;/a&gt;: FDR&lt;/strong&gt;&lt;br&gt;&#xA;Height: 7.62 in (19.4 cm)&#xA;Width: 4.88 in (12.4 cm)&#xA;Depth: 19.56 in (49.7 cm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Universal Avionics Systems &lt;a href=&quot;http://www.uasc.com/products/cvfdr.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;CVFDR&lt;/a&gt;: CVR/FDR&lt;/strong&gt;&lt;br&gt;&#xA;Height 6.1 in (15.5 cm)&lt;br&gt;&#xA;Width 4.9 in (12.4 cm)&lt;br&gt;&#xA;Depth 8.0 in (20.3 cm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;L3 &lt;a href=&quot;http://www2.l-3com.com/edi/srvivr.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;SRVIVR&lt;/a&gt;: CVR/FDR&lt;/strong&gt;&lt;br&gt;&#xA;standard configuration:&lt;br&gt;&#xA;Height: 3.25 in (8.26 cm)&lt;br&gt;&#xA;Width 5.55 in (14.1 cm)&lt;br&gt;&#xA;Depth: 6.55 in (16.6 cm)&lt;br&gt;&#xA;extended configuration:&lt;br&gt;&#xA;Height: 3.25 in (8.26 cm)&lt;br&gt;&#xA;Width: 5.55 in (14.1 cm)&lt;br&gt;&#xA;Depth: 7.2 in (18.3 cm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;L3 &lt;a href=&quot;http://www.l-3ar.com/PDF_Files/MKT048_FA2100CVR.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FA2100&lt;/a&gt;: CVR&lt;/strong&gt;&lt;br&gt;&#xA;Height 5.5 in. (14.00 cm)&lt;br&gt;&#xA;Width 5.0 in. (12.70 cm)&lt;br&gt;&#xA;Depth 12.6 in. (32.00 cm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were asking something else, see:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5041/how-much-data-do-fdr-and-cvr-generate-on-commercial-jets&quot;&gt;How much data do FDR and CVR generate on commercial jets?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or other questions already asked here.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-08-01T22:10:55.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7979" PostTypeId="2" ParentId="7967" CreationDate="2014-08-02T13:10:32.910" Score="5" Body="&lt;p&gt;I begin with the premise that there are generally &lt;strong&gt;3 different types of anti-aircraft missile&lt;/strong&gt; systems. These are  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) Man-Portable Air-Defense System (MANPADS) also called Very Short Range Air Defense Systems(VSHORADS) for example RBS-70 , Verba , Starstreak , &#xA;(b) Ground based Medium-Range Surface-to-air missile systems for example BUK-3  and &#xA;(c) Long Range Air Defense Systems  for example Patriot MIM-104 and S-300V. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now , the testing of these 3 different types are obviously different , however the cornerstone of these tests regardless of the type would include :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) Digital Simulation of launches - almost a million launches are simulated ;&#xA;(b) Hardware-in-the-loop simulations – thousands of  tests for each system &#xA;with actual missile seekers and jammers&#xA;(c) Flight Tests simulation &#xA;(d) Functional configuration audit to verify compliance with system functional requirements&#xA;(e) Live Fire tests - carried out on unmanned aerial vehicles that serves as targets &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://sites.google.com/site/samsimulator1972/home&quot; rel=&quot;noreferrer&quot;&gt;https://sites.google.com/site/samsimulator1972/home&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are generally 3 main parts in a missile . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) The rear section contains electronic packages , a battery and the rudder mechanism &#xA;(2) The central section contains the sustained motor and wings &#xA;(3) The forward section contains electronic packages , the gyro and warhead &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore , Tests have to be conducted at  the component, subsystem, or system level as well .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://pvo.guns.ru/images/other/sweden/rbs70/aaz/Missile_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Missile Sub sections&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Countermeasures for air defense systems are categorized into active and passive systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) Active countermeasures are for example flares and directed infrared countermeasures (DIRCM)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Passive countermeasures include infrared signature reduction, fuel tank inerting and redundant controls&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tests are carried out for Flares , Chaffs and  Infrared .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chaff cuts are tested for optimization so as  to provide a broadband radar return .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The various tests carried out on Chaffs are related to their Performance Requirements shown in the image below &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9TPgg.jpg&quot; alt=&quot;Chaff Performance Requirements&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Flare consists of  (1) a firing cap, (2) a powder charge wadding between the charge and the bullet, and (3) a wad at the end that keeps everything in place.  The electrical firing “cap” creates a gas that ejects the plastic or nylon slider, 2 felt spacers that hold everything in place, and the end cap. All these 3 components have to be tested . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For evaluation of effectiveness against two-color systems, an integrated color ratio filter system is used to enable flares and target representation to contain the appropriate &#xA;amount of energy in each spectral region of interest . &lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-02T13:10:32.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7980" PostTypeId="1" AcceptedAnswerId="7983" CreationDate="2014-08-02T16:41:29.777" Score="12" ViewCount="2409" Body="&lt;p&gt;I've discussed this with my instructor numerous times, and I have the concept memorized, but from an aerodynamic point of view, I can't see how the angle of relative wind to chord line is different per wing (assuming a Cessna 172, if that makes much of a difference).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings are essentially a straight line over the top of the plane, and relative wind is a single vector - to me, it looks like they should have identical AoAs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you know of a graphic or video, I think it would help explain best.&lt;/p&gt;&#xA;" OwnerUserId="204" LastActivityDate="2015-05-07T20:01:08.170" Title="In a slip or skid, how does one wing have a higher angle of attack and more lift?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7981" PostTypeId="2" ParentId="7972" CreationDate="2014-08-02T16:58:19.000" Score="7" Body="&lt;p&gt;It stands for metric tons, as indicated in the &quot;GEN 2.1 Measuring system, aircraft markings, holidays&quot; section of the AIP that you linked to as one of the units for mass. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the number format appears to be wrong and they most likely intended 45.000 metric tons, which works out to about 99,000 lbs. and is a somewhat common point to use for aircraft classification in other countries.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-02-21T20:23:18.800" LastActivityDate="2015-02-21T20:23:18.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7982" PostTypeId="1" CreationDate="2014-08-02T17:37:40.610" Score="5" ViewCount="985" Body="&lt;p&gt;I have a question of the book  &quot;The foundations of helicopter flight&quot; by Simon Newman.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is from page 186:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dh0iA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) How can we feel gyroscopic effect of tail rotor with hover spot turns?&lt;/p&gt;&#xA;" OwnerUserId="1057" LastEditorUserId="19" LastEditDate="2015-02-23T13:02:08.763" LastActivityDate="2015-12-31T08:51:07.037" Title="Are gyroscopic effects of tail rotor noticeable with hover spot turns?" Tags="&lt;helicopter&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7983" PostTypeId="2" ParentId="7980" CreationDate="2014-08-02T18:12:51.303" Score="11" Body="&lt;p&gt;You are mostly correct, but the fuselage distorts the airflow in sideslip such that the windward wing sees a higher angle of attack near the root, and the leeward wing a lower angle of attack. Please see the drawing below for an explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ogOgZ.png&quot; alt=&quot;Comparison of two wing positions and their effects in crossflow&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blue lines show the sideward component of air flow and the red arrows the resulting rolling moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why low wing airplanes need more dihedral, and high wing planes like your 172 almost none. Wing sweep adds more directional stability, and then you even find aircraft with pronounced anhedral, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Siddeley_Harrier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Harrier jump jet&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-104 Starfighter&lt;/a&gt;. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/an-225-wing-configuration&quot;&gt;this answer&lt;/a&gt; for more detail on this.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-07T20:01:08.170" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7984" PostTypeId="1" CreationDate="2014-08-02T18:56:59.080" Score="7" ViewCount="1412" Body="&lt;p&gt;&lt;a href=&quot;http://youtu.be/vJZzEtfMfw0&quot; rel=&quot;nofollow&quot;&gt;Here is a video of the aircraft in flight.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://volocopter.com/index.php/en/&quot; rel=&quot;nofollow&quot;&gt;Volocopter&lt;/a&gt; Looks like it would fly quite differently than a helicopter. Is that true? Does that matter? Is it still a helicopter license that's needed?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="62" LastEditDate="2016-07-08T15:01:50.850" LastActivityDate="2018-02-23T01:31:06.563" Title="What license is needed to fly the electric &quot;Volocopter&quot; helicopter?" Tags="&lt;faa-regulations&gt;&lt;helicopter&gt;&lt;electric-engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="7985" PostTypeId="2" ParentId="7984" CreationDate="2014-08-02T20:08:40.047" Score="8" Body="&lt;p&gt;The German transportation ministry &lt;a href=&quot;http://ecosummit.net/uploads/eco12_141112_1220_alexanderzosel_evolo.pdf%20%20%20%20%20slide%2011.&quot; rel=&quot;nofollow&quot;&gt;has decided to create a new aircraft category for this machine&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://aviationweek.com/blog/germany-gives-all-electric-rotorcraft-lift&quot; rel=&quot;nofollow&quot;&gt;Aviation Week&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Karlsruhe-based E-volo says the Ministry has commissioned a two- to three-year trial program to create a new category of ultralight aviation to cover the two-seat VC200 rotorcraft now in development. [...] Under the trial program, the German Ultralight Aircraft Association, Sport Aircraft Association and Federal Aviation Office will work with E-volo to create a manufacturing specification, legal regulations and training requirements for the new &quot;Volocopter&quot; ultralight rotorcraft category.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So according to this, the exact licence, and training requirements will be deteremined by the currently running trial program. It seems the manufacturer tries to position the craft as some sort of rotational-wing ultralight.&lt;/p&gt;&#xA;" OwnerUserId="3067" LastEditorUserId="1696" LastEditDate="2016-07-08T14:52:24.153" LastActivityDate="2016-07-08T14:52:24.153" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7986" PostTypeId="1" CreationDate="2014-08-02T20:23:45.870" Score="7" ViewCount="2074" Body="&lt;p&gt;If I have aircraft details such as the callsign, transponder code, and ads-b info, how can I look up the departure and arrival airdrome? Is there an API to obtain this information in a programmatic way? How does &lt;a href=&quot;http://flightradar24.com&quot;&gt;flightradar24&lt;/a&gt;, for example, obtain this data?&lt;/p&gt;&#xA;" OwnerUserId="3068" LastEditorUserId="6" LastEditDate="2014-08-02T23:38:49.060" LastActivityDate="2017-09-07T19:26:39.990" Title="How can I get flight destination from ADS-B?" Tags="&lt;ads-b&gt;&lt;flightradar24&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7987" PostTypeId="1" AcceptedAnswerId="7993" CreationDate="2014-08-03T00:53:12.463" Score="12" ViewCount="6361" Body="&lt;p&gt;I've flown a few times in my life, both in economy and executive class. Every time I fly in executive, during takeoff, there is a different noise from the engines. In economy class (behind the engines) the wind sound dominates, but in the executive class you hear the noise in the video below until you're high in the skies. Why is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Q6-lLWtFajQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="2353" LastEditorUserId="1696" LastEditDate="2016-07-08T19:52:14.900" LastActivityDate="2016-07-08T19:52:14.900" Title="What is the buzzing noise generated by the engines in this 777 takeoff video?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;&lt;noise&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="7989" PostTypeId="1" AcceptedAnswerId="7991" CreationDate="2014-08-03T15:18:46.627" Score="11" ViewCount="782" Body="&lt;p&gt;I ask as a dilettante, so please feel free to correct or emend this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I transcribe the radio altimeter enunciations for &lt;a href=&quot;https://www.youtube.com/watch?v=Vr-0LiQA6wo&quot;&gt;https://www.youtube.com/watch?v=Vr-0LiQA6wo&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;0m 21s: 400&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;0m 23s: &lt;strong&gt;400&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;0m 36s: 100 &lt;strong&gt;above&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;0m 41s: 200&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;0m 49s: &lt;strong&gt;100&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Are the radio altimeter verbalisations part of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_proximity_warning_system&quot;&gt;Ground Proximity Warning System&lt;/a&gt;? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Why was 400 uttered twice? Isn't the A380 descending?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Same question for 100 at 49 s, compared with 36 s? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What does the &lt;strong&gt;above&lt;/strong&gt; imply?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="128" LastEditorUserId="19" LastEditDate="2016-11-01T22:22:00.067" LastActivityDate="2016-11-01T22:22:00.067" Title="What is the reason for these strange radio altimeter calls?" Tags="&lt;landing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7990" PostTypeId="1" CreationDate="2014-08-03T17:00:42.203" Score="6" ViewCount="916" Body="&lt;p&gt;This is a followup to &lt;a href=&quot;https://aviation.stackexchange.com/q/7984/2168&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the FAA decide whether a new aircraft will is deemed to be a helicopter for licencing and registration purposes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a law or regulation? Are there guidelines? Is there any case law where a manufacturer challenged a particular classification?&lt;/p&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-08-05T12:08:44.817" Title="How does the FAA decide whether an aircraft is deemed a helicopter?" Tags="&lt;helicopter&gt;&lt;aircraft-registration&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="7991" PostTypeId="2" ParentId="7989" CreationDate="2014-08-03T18:10:04.153" Score="15" Body="&lt;p&gt;&quot;Four hundred&quot; was likely annunciated twice due to a bit of a dip in the terrain that would cause it to &lt;em&gt;pass&lt;/em&gt; the 400ft level twice. The &quot;hundred above&quot; call-out is for 100 feet above decision height to let the crew know they will need to make their decision soon to either continue or go around. After that, you hear the &quot;two hundred&quot; and &quot;minimum&quot; call-outs right after one another. The &quot;one hundred&quot; call-out afterwards signifies 100 feet above ground level.&lt;/p&gt;&#xA;" OwnerUserId="287" LastEditorUserId="287" LastEditDate="2014-08-05T11:05:10.383" LastActivityDate="2014-08-05T11:05:10.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="7993" PostTypeId="2" ParentId="7987" CreationDate="2014-08-03T19:57:17.207" Score="13" Body="&lt;p&gt;That buzzing sound is from the tips of the fan blades breaking the sound barrier.  When you're sitting farther back in the airplane, that sound is overpowered by the sound of the exhaust, which is the roaring part of a jet engine's sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in general, sit forward of the wing, you'll hear the fan sound (the buzz), sit aft of the wing and you'll hear the exhaust sound (roar).  It'll vary from airplane to airplane of course, and when thrust is reduced and the fan speed slows, the buzz will subside.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-08-03T19:57:17.207" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="7995" PostTypeId="1" AcceptedAnswerId="7996" CreationDate="2014-08-04T02:35:39.770" Score="10" ViewCount="6847" Body="&lt;p&gt;As the title suggests, Is a magnetic compass required equipment for VFR (day) flight in powered civil aircraft? I have always been under the impression it was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question arises from reading &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.205&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFR section 91.205, article b&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b) Visual-flight-rules (day). For VFR Flight during the day, the&#xA;  following instruments&#xA;         and equipment are required:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;br&gt;&#xA;     (3) Magnetic direction indicator&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This sort of implies I can use anything, including my GPS that indicates magnetic direction. Is my interpretation correct? Has this changed recently? &lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="34686" LastEditDate="2020-04-12T23:11:19.630" LastActivityDate="2020-04-12T23:11:19.630" Title="Is a magnetic compass required for VFR (day) flight in powered aircraft?" Tags="&lt;faa-regulations&gt;&lt;flight-instruments&gt;&lt;visual-flight-rules&gt;&lt;airplane&gt;&lt;far-91&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="7996" PostTypeId="2" ParentId="7995" CreationDate="2014-08-04T02:55:31.857" Score="11" Body="&lt;p&gt;The phrase &amp;quot;magnetic direction indictor&amp;quot; is interpreted as &amp;quot;magnetic direction-indicator&amp;quot;, not &amp;quot;magnetic-direction indicator&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;You need a device based on magnetism that indicates your direction. That could be a floating-card type compass, or a fluxgate compass, for example.&lt;/p&gt;&#xA;&lt;p&gt;Some interpretation of this phrase is given in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1311-1C.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 23.1311-1C&lt;/a&gt; section 8.8:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Under VFR operation, part 91, § 91.205, requires a magnetic direction indicator (that is normally intended to be a compass) for heading information.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;Section 23.1303(c), Amendment 23-62, amended the requirement from “A direction indicator (non-stabilized magnetic compass)” to “A magnetic direction indicator.” As new technology becomes more affordable for part 23 airplanes, many electronic flight instrument systems will use magnetically stabilized direction indicators (or electric compass systems) to measure and indicate the airplane heading to provide better performance.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;Part 23 does not prescribe specific accuracy requirements for magnetic gyroscopically stabilized heading systems. Specific accuracy requirements for avionics may be found in the related TSO and, as acceptable means of compliance to § 23.1301, in ACs, notices, or policy statements/letters.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Further, installation of the magnetic direction indicator is regulated by §23.1327:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Each magnetic direction indicator must &lt;em&gt;be installed&lt;/em&gt; so that its accuracy is not excessively affected by the airplane’s vibration or magnetic fields.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user2168" LastEditorUserId="-1" LastEditorDisplayName="user2168" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-04T19:40:10.650" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="7997" PostTypeId="1" AcceptedAnswerId="7998" CreationDate="2014-08-04T04:49:19.853" Score="4" ViewCount="17362" Body="&lt;ol&gt;&#xA;&lt;li&gt;Is there an explanation better yet equally pithy than &lt;a href=&quot;http://www.flightsim.com/vbfs/showthread.php?250495-Difference-between-course-and-heading&amp;amp;p=1688400#post1688400&quot; rel=&quot;nofollow noreferrer&quot;&gt;the beneath&lt;/a&gt;, in fewer than 50 words?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Course is the direction in which the aircraft is flying over the ground. Heading is the direction in which the aircraft is pointing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This quote motivated me to question &lt;a href=&quot;http://www.flightsim.com/vbfs/showthread.php?250495-Difference-between-course-and-heading&amp;amp;p=1688407#post1688407&quot; rel=&quot;nofollow noreferrer&quot;&gt;the quote beneath&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[2.] See it like this... When Tomtom directs you from Amsterdam to Barcelona via Paris, Barcelona is your final 'course', but for now... you're 'heading' towards Paris... (taking in mind that you just left from Amsterdam...)&lt;/p&gt;&#xA;&lt;p&gt;[3.] Other example: If you're doing an approach for landing at, let's say, LEBB (Bilbao) Airport on RWY 30, your Course is 300 but you can have various 'headings' TOWARDS your final course, Course 300 for RWY 30.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;Why would heading and course need be controlled separately? If I'm flying to Paris first, then wouldn't I just input the heading to fly to Paris? Only after reaching Paris would I change the heading for Barcelona. Isn't 'course' redundant?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the 'other example' above, isn't 'heading' redundant? Wouldn't I just input the course for Rwy 30 which is by definition 300?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does anything above explain &lt;a href=&quot;http://en.wikipedia.org/wiki/Course_%28navigation%29#Aircraft_heading&quot; rel=&quot;nofollow noreferrer&quot;&gt;this picture&lt;/a&gt;, where the crosswind requires the plane to angle its nose to land?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-05-19T05:23:44.317" Title="Why separate autopilot controls for course and heading?" Tags="&lt;heading&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="7998" PostTypeId="2" ParentId="7997" CreationDate="2014-08-04T05:31:41.767" Score="13" Body="&lt;p&gt;First, I'll try for the 50 words or less: Course is the line across the ground that you want to go. Heading is where you have to point the aircraft to fly that line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's less than 50 words, but I'm not sure it's any better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the obvious first. Let's say, over a short distance, you want to fly a course of 270 degrees true. If you fly the airplane on a heading of 270 degrees, you will fly that course ONLY if there is no wind, which for all practical purposes is never the case. If there was a wind from the north, you would have to maintain a heading greater than 270 degrees to make good a course of 270 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, you can never say that the course between point A and point B is a single value in degrees unless those two points are very close together. If you draw a line between point A and point B and those two points are not close together, and then measure the course leaving point A (the angle between north and the line as it leaves point A) you will find that it is different from the course as you arrive at point B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can, however, tell the autopilot to fly a direct course from point A to point B and it will do it, changing the heading as necessary to account for the wind and fly that course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, why does an autopilot need to have a &quot;course&quot; function and a &quot;heading&quot; function. In my experience, the greatest single use of the heading function is when a controller is vectoring you and tells you to fly heading so and so. The second is when a reroute from your existing course is necessary, and you use the heading function to keep the airplane going straight ahead for a bit while you redo the revised course setting you want to use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you forget to again use the course function after putting in the revised course, the airplane will continue on the heading it was on while you were updating the course, and you will shortly be off course. That mistake has been responsible for aircraft being hundreds of miles off course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the first Gulf War, I heard a Canadian controller inform a USAF aircraft that they were over 300 miles off course when Canadian radar picked them up prior to landfall coming in from Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A captain at the first 747 carrier I flew for got over 50 miles off course and was demoted to First Officer. He had forgotten to switch from the heading function to the course function.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, as an added problem, if you choose to define your course in degrees magnetic, you must also account for the change in magnetic variation as you proceed along that course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insofar as item 4 is concerned, you (or the autopilot) is going to change heading as necessary to keep the airplane proceeding along the course as defined by the runway centerline. There's a bit of confusion of terms here in that runway directions are typically referred to as the runway heading rather than the runway course.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-08-04T05:38:19.920" LastActivityDate="2014-08-04T05:38:19.920" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="7999" PostTypeId="1" CreationDate="2014-08-04T06:36:28.277" Score="1" ViewCount="809" Body="&lt;p&gt;I checked &lt;a href=&quot;http://www.airliners.net/forum-legacy?fid=general_aviation&amp;amp;pid=2976358&quot; rel=&quot;nofollow noreferrer&quot;&gt;this post on Airliners.net&lt;/a&gt; , but the formatting is hard to read, and the information or hearsay may not be trustworthy. Also, I'm hoping for a more efficient, efficacious method, rather than researching each accident separately. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd wanted to be advised if pilots, suspected of (provable, veritable) pilot error, were still flying: &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Qantas Flight 1&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_1420&quot; rel=&quot;nofollow noreferrer&quot;&gt;American Airlines Flight 1420&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet I'd be heartened and inspired by heroic or esteemed pilots, like those for &lt;a href=&quot;http://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow noreferrer&quot;&gt;United Airlines Flight 232&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="1696" LastEditDate="2019-11-21T19:23:17.377" LastActivityDate="2019-11-21T19:23:17.377" Title="How to determine if pilots in crashes flew again?" Tags="&lt;pilots&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8000" PostTypeId="1" AcceptedAnswerId="8947" CreationDate="2014-08-04T07:19:45.160" Score="49" ViewCount="172722" Body="&lt;p&gt;&lt;a href=&quot;https://english.stackexchange.com/a/54659/50720&quot;&gt;This answer&lt;/a&gt; from English.SE does not focus on aviation, and does not explain 'Track'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In basic, simple English, would you please compare and contrast all 5 terms in my question's title? The differences between 'course' vs 'heading' was generously explained &lt;a href=&quot;https://aviation.stackexchange.com/a/7998/128&quot;&gt;in this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-10-08T10:19:12.937" Title="What are the differences between Bearing vs Course vs Direction vs Heading vs Track?" Tags="&lt;navigation&gt;&lt;terminology&gt;&lt;heading&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="26" ContentLicense="CC BY-SA 3.0" />
  <row Id="8001" PostTypeId="2" ParentId="7999" CreationDate="2014-08-04T08:10:00.437" Score="8" Body="&lt;p&gt;So pilots are supposed to be flawless? Are you even aware that often an incident or accident is blamed on &quot;pilot error&quot; simply to prevent lawsuits against companies (though that's more often the case when the pilot died and can't defend himself)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rest assured if someone makes a serious mistake they're going to get training and are likely to be grounded for a while during that. They're also going to have to live with the resulting damaged reputation, and if people died or were seriously injured with the mental anguish of the feeling of guilt that results (which more than likely will cause them to retire from flying).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are you also going to demand that anyone with a driver's license who ever was in an accident lose it permanently?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's life, shit happens as they say. Sometimes the best you can do isn't good enough, and the fact that there were no other options ends up being blamed on you for no other reason than that someone, somewhere, is looking for a scapegoat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a pilot who ends up landing hard in bad weather, resulting in a passenger who ignored the seatbelts sign to hit her head and break her nose ends up getting blamed for the hard landing causing the injury for no other reason than that it's better PR for the company to do that than to go public about the fact that the passenger ignored the safety rules and wasn't wearing that seatbelt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things like that happen more often than you think, and you want that pilot to as a result lose his license and his job?&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="11215" LastEditDate="2019-11-21T18:58:23.707" LastActivityDate="2019-11-21T18:58:23.707" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="8002" PostTypeId="2" ParentId="8000" CreationDate="2014-08-04T08:40:05.357" Score="15" Body="&lt;p&gt;I will try to explain as simple as possible, though I'm not a professional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Heading&lt;/strong&gt;&lt;br&gt;&#xA;It is the value the compass shows you while you fly your plane, relative to Earth's magnetic field. But your heading is not where exactly your plane goes. Why? because in most of the cases (if not all) there is wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Track&lt;/strong&gt;&lt;br&gt;&#xA;This is the aircraft's actual &quot;path&quot; over the ground when wind effect is &quot;added up&quot; to the aircraft's velocity. You need track for navigation since this is where you actually go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bearing&lt;/strong&gt;&lt;br&gt;&#xA;If it is from north (true or magnetic): Having two locations A and B, bearing of B to A is the angle measured clockwise from north to B having as angle vertex location A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is relative: Having 2 locations A and B, bearing of B to A is the angle measured clockwise from point A forward direction to B having as angle vertex location A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the following picture, red is true bearing, blue is relative bearing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KooMm.png&quot; alt=&quot;True vs relative bearing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Course&lt;/strong&gt;&lt;br&gt;&#xA;This is the one and only path you can follow to reach one specific point. Suppose that you are instructed to &quot;approach the XYZ point from the east&quot; that means course 270 to the XYZ point. The following pictures depicts the concept: 270 course to XYZ is the green one. The red one goes to XYZ but it is not 270, the orange is 270 but doesn't end to XYZ.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/htSz3.png&quot; alt=&quot;Course to point explanation&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For more information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Wind_triangle&quot; rel=&quot;noreferrer&quot;&gt;Wind triangle&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_heading#Aircraft_heading&quot; rel=&quot;noreferrer&quot;&gt;Aircraft heading&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Bearing_(navigation)&quot; rel=&quot;noreferrer&quot;&gt;Bearing&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="878" LastEditorUserId="65" LastEditDate="2015-01-28T14:39:43.097" LastActivityDate="2015-01-28T14:39:43.097" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8003" PostTypeId="2" ParentId="7997" CreationDate="2014-08-04T10:52:12.400" Score="-3" Body="&lt;p&gt;LePressentiment,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its simple.  Its all about the wind (and to a lesser degree magnetic variation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everything else you've mentioned is completely irrelevant, air traffic control, waypoints etc..... all completely irrelevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You calculate your correction angle and you fly that heading.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ATC ask you to temporarily fly a new heading for traffic avoidance purposes, then its still up to you to figure out how you're going to rejoin your original course (i.e. the headings you'll need to fly taking into account wind) when they are done with you.&lt;/p&gt;&#xA;" OwnerUserId="3081" LastActivityDate="2014-08-04T10:52:12.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8004" PostTypeId="2" ParentId="7997" CreationDate="2014-08-04T11:22:50.217" Score="1" Body="&lt;p&gt;I will try to answer the question itself leaving out the heading/track discussion:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Because these are 2 different things.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heading hold &quot;simply&quot; holds the aircraft on a specific heading. If you continue this heading for a long time, you will most probably follow a &lt;a href=&quot;http://en.wikipedia.org/wiki/Rhumb_line&quot; rel=&quot;nofollow&quot;&gt;loxodrome&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Course hold function on the other hand will be used in conjunction with a navaid to follow a specific path to a specific navaid. FAA advanced avionics handbook &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/advanced_avionics_handbook/media/aah_ch04.pdf&quot; rel=&quot;nofollow&quot;&gt;chapter 4&lt;/a&gt; under &quot;Course Intercepts&quot; in page 4-11 describes the concept itself. Note that the exact procedure of engaging a course might be different for each aircraft type.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2014-08-04T11:22:50.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8006" PostTypeId="2" ParentId="7997" CreationDate="2014-08-04T11:40:21.803" Score="2" Body="&lt;p&gt;While the wind correction angle is the main difference that comes to peoples mind, this has nothing to do with the reason the autopilot is providing these two operating modes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One is a stabilization mode (heading), the other is a guidance function(course). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An autopilot can very easily fly a constant heading without external inputs or guidance. It might not even need a compass in some cases, just a turn coordinator to provide it with yaw rates. This makes the heading mode available in all but the direst failures. Easy to implement, easy to use, and available practically in any autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a course requires guidance. Autopilot flies this mode (in an outer-feedback loop) by setting a desired heading (on the inner feedback loop). You might say the course mode runs on top of the heading mode. But it needs a lot of external data: groundspeed, windspeed, navigational signals wether GPS or a combination of VOR/DME. It'll be one of the first functions to lose when the autopilot goes into a degraded mode, it will be more complicated to build (ie. expensive) and more complicated to use (course from where? to where? on what NAV? )&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-08-04T11:40:21.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8007" PostTypeId="2" ParentId="1906" CreationDate="2014-08-04T13:48:45.643" Score="7" Body="&lt;p&gt;The other answers describe well why engine power is necessary during approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would just like to add that powering off the engines would not decrease sound levels as much as you would expect. Indeed, other devices such as landing gears and high lift devices produce noise (especially slats) on the same order of magnitude as the engines and those are obviously necessary during landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has been pointed out that I should back my claims with references and I agree that it is a good habit to take. Unforntunately, I have to admit that I only had some faint memories of a poster I had seen somewhere. Some googling led to this study [1] which provides some hard data on the A340. I am not familiar with the study but seems that they have managed to identify different noise sources and their related noise levels as follows :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Engines ~ 130 dB&lt;/li&gt;&#xA;&lt;li&gt;Landing gear ~ 127 dB&lt;/li&gt;&#xA;&lt;li&gt;Slats, flaps ~ 124 dB&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So the engines are only 3 dB louder than the landing gear themselves just 3 dB louder than the slats and flaps. (It would seem that, from the ground at least, slats are only marginally louder. So I was wrong about that, huh!) In another study [2] (that I am also unfamiliar with), it appears in their recommendations that the removal of a noise source only 3 dB louder than others will only result in a 3 dB reduction of the overall noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1] Sijtsma, Pieter, and Robert Stoker. &quot;Determination of absolute contributions of aircraft noise components using fly-over array measurements.&quot; AIAA paper 2958.2004 (2004): 10.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[2] Lockard, David P., and Geoffrey M. Lilley. &quot;The airframe noise reduction challenge.&quot; NASA/TM 213013 (2004): 2004.&lt;/p&gt;&#xA;" OwnerUserId="2855" LastEditorUserId="2855" LastEditDate="2014-08-04T16:06:46.340" LastActivityDate="2014-08-04T16:06:46.340" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8008" PostTypeId="1" CreationDate="2014-08-04T15:28:35.460" Score="4" ViewCount="1528" Body="&lt;p&gt;Regular ATC operates under regulations like &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/Index.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Order 7110.65&lt;/a&gt; when they control traffic. At an air show, there is typically an &quot;air boss&quot; that manages aircraft within the air show area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the air boss required to have the same training and certification as a regular controller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the air boss operate under the same regulations as regular controllers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the air boss have the same authority as regular controllers?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-08-04T16:01:00.383" Title="What is the authority of the Air Boss at an airshow?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airshow&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8009" PostTypeId="2" ParentId="7999" CreationDate="2014-08-04T15:57:17.013" Score="18" Body="&lt;p&gt;How can I determine if a driver who was involved in an automobile accident is still driving?&lt;br&gt;&#xA;The answer is &quot;They probably are.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broadly, unless the pilot died or the FAA (or equivalent authority) revoked their license as a result of their actions there is no reason the pilot wouldn't still be flying unless they decide to hang up their wings for personal reasons.&lt;br&gt;&#xA;They may not be flying for the same airline, and certainly will have had some sort of remedial training (particularly if they were involved in an incident where pilot error was the cause), but damaging an aircraft is usually not a career-killing move unless one makes a habit of it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you want to know for certain about a particular flight crew you would need to research each accident separately (locate the pilots' information - name or certificate number - and check something like &lt;a href=&quot;https://amsrvs.registry.faa.gov/airmeninquiry/&quot;&gt;the FAA airman records branch&lt;/a&gt; to see if the pilot still holds a valid certificate and medical.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-04T15:57:17.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8010" PostTypeId="2" ParentId="8008" CreationDate="2014-08-04T16:01:00.383" Score="3" Body="&lt;p&gt;Air bosses who orchestrate air shows &lt;strong&gt;do not receive special training or certification&lt;/strong&gt; . Infact FAA also lacks the resources to inspect all aircraft that participate in air shows &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA doesn't have certification standards for air bosses . Waivers for customary flight standards are provided to air shows, which then hire people to direct planes in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no training in place right now for an air boss&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.rgj.com/story/news/2014/03/23/ntsb-hearing-addresses-distance-between-race-course-and-spectators-other-issues/6587627/&quot; rel=&quot;nofollow&quot;&gt;http://www.rgj.com/story/news/2014/03/23/ntsb-hearing-addresses-distance-between-race-course-and-spectators-other-issues/6587627/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However,  typically former air-traffic controllers with a great deal of aviation experience are hired as Air Bosses at Air Shows .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air boss implements the standards on the FAA waiver&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firms like ICAS provide Air Boss training &lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-04T16:01:00.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8011" PostTypeId="2" ParentId="7886" CreationDate="2014-08-04T16:17:37.933" Score="0" Body="&lt;p&gt;How difficult is it to avoid ground loop in practice?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not difficult. Practice makes perfect.  That's why in real world type ratings exist, you get extra training to fly taildragger types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Desktop PC simulators are a waste of time and not at all realistic, the &quot;full-motion&quot; ones airlines use are lightyears better... but obviously nothing beats the real thing !&lt;/p&gt;&#xA;" OwnerUserId="3083" LastActivityDate="2014-08-04T16:17:37.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8012" PostTypeId="1" AcceptedAnswerId="8013" CreationDate="2014-08-04T19:07:58.790" Score="24" ViewCount="13546" Body="&lt;p&gt;Assume that a 747 is flying at cruising altitude and speed. If the pilot decided (for a presumably good reason), to turn the plane 180 degrees,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How quickly could the turn be completed?&lt;/li&gt;&#xA;&lt;li&gt;How wide would the turn radius be?&lt;/li&gt;&#xA;&lt;li&gt;How much altitude would be lost, if we're not assuming a level turn?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;EDIT: I learned something new from both of the great answers below. I accepted the one that was easier to follow. Since both answers assumed a level flight, I have added a #3.&lt;/p&gt;&#xA;" OwnerUserId="3085" LastEditorUserId="37528" LastEditDate="2019-02-25T19:59:58.457" LastActivityDate="2019-02-25T19:59:58.457" Title="What does it take to turn a 747 around 180 degrees?" Tags="&lt;airliner&gt;&lt;flight-controls&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8013" PostTypeId="2" ParentId="8012" CreationDate="2014-08-04T21:15:34.627" Score="25" Body="&lt;p&gt;How long, and how wide of a turn depends entirely on three things:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the true airspeed.&lt;/li&gt;&#xA;&lt;li&gt;What is the bank angle of the turn?&lt;/li&gt;&#xA;&lt;li&gt;Is level flight maintained during the turn.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Since it's easiest to calculate, and presumably what you intended, we'll assume #3 is true (level flight). However, if you really needed to get turned around fast, turning in a descent will give you a tight turn without the extra g-forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise Speed for a 747 depends on altitude, generation, company guidelines, etc, but we'll go with Mach 0.85 for this example, which seems to be in the ballpark. If we say it's cruising at 35,000 feet in standard atmospheric conditions, that comes out to 490 knots TAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, pick a bank angle. A reasonable bank angle for that airplane with passengers on board is 25°, and you could probably get away with 30°. Anything beyond that will cause passengers to complain. Of course, if it's an emergency you might consider something higher. Just remember, the higher the bank angle, the stronger the g-forces which will be felt by the people inside, and the aircraft itself, which has structural limitations. The G-force can be calculated using:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;gforce = \frac{1}{\cos(bank)}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For an example, let's select 25° bank since that's the most realistic.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Radius&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Calculate the radius of the turn using this formula, slightly modified &lt;a href=&quot;http://en.wikipedia.org/wiki/Rate_of_turn&quot; rel=&quot;noreferrer&quot;&gt;from Wikipedia&lt;/a&gt; to give nmi instead of feet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;Radius\ of\ turn\ in\ nautical\ miles= \frac{velocity^2}{68579 \times \tan(bank)}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which gives us:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;7.51nmi = \frac{490^2}{68579 \times \tan(25°)}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the turn itself would be about 15 nautical miles wide (≈ 91,000 feet) not accounting for wind.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Distance Traveled&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Using basic geometry, the distance traveled for a 180° turn is $d = r\pi$ (half the circumference of a circle), so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;23.59= 7.51\pi&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Giving us 23.59 nautical miles traveled.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Duration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;time\ in\ minutes = \frac{distance \times 60}{TAS}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, at 490 knots (nautical miles per hour) and 25° bank, &lt;strong&gt;it would take about 2 minutes, 53 seconds to complete the turn.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;2.89 = \frac{23.59 \times 60}{490}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could go through and calculate the results for any speed and bank angle you want. This is true regardless of the type of airplane in question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Turning in a Descent&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Your edited question asks how much altitude would be lost if it were not a level turn. There is also no single answer to this question because it depends entirely on how you perform the maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason you may &lt;em&gt;have to&lt;/em&gt; descend in a turn is because the increased lift results un increased induced drag, and the aircraft engines may not have enough power to compensate, resulting in the decreased airspeed, and possibly a stall. In this case, the equations for calculating the turn radius are exactly the same as in level flight. The amount of altitude lost will depend on the descent rate required in order maintain airspeed, which will vary depending on the engine power available, the weight of the aircraft, and the drag curve at the given speed and AoA. &lt;a href=&quot;https://aviation.stackexchange.com/a/8014&quot;&gt;Peter Kämpf's answer&lt;/a&gt; gives an example of what this might look like for a 747 in a 1.5g turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another version of a turning descent would be an accelerated descent. The advantage in this case it that it would allow turns to be made without additional g-force. The disadvantage is that you'll be accelerating downwards instead of descending at a constant rate. This can get out of hand &lt;em&gt;very&lt;/em&gt; quickly and would only be good for very short duration turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate this disastrous option, let's look at what would happen in a 1g turn at the same 25° and 490 knots TAS. Since the math is more complicated, it'll be easier to talk about this portion in metric units. Here's a conversion table:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;1 nautical mile = 1852 meters&#xA;1 knot = 0.514444 meters per second&#xA;1 foot = 0.3048 meters&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;First, in order to maintain a constant 1g, the lift vector is simply rotated in the turn (instead of rotated &lt;em&gt;and increased&lt;/em&gt; in order to maintain altitude). Therefore, the magnitude of our lift vector will be equal to the acceleration due to gravity near the Earth's surface. We'll round that to 9.8 m/s/s.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Inward Acceleration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Our acceleration towards the center of the turn $a_c$ (the portion of our lift vector pointed inwards instead of up) can be determined using the following equation where $\theta$ is the bank angle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;\sin(\theta) = \frac{a_c}{g}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Solving for $a_c$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;a_c = g\sin(\theta)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;4.142 = 9.8\sin(25°)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Radius&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;So 4.142 meters per second per second is how fast, at 25° of bank, and 1g, we'll be accelerating towards the center of the turn. With that, information, along with our known velocity, we can calculate the radius of the turn using this equation where $v$ is our velocity in meters per second, and $R$ is the radius in meters:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;R = \frac{v^2}{a_c}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plug in our numbers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;15341 = \frac{(490 \times 0.514444)^2}{4.142}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This comes out to a radius of 15341 meters (8.28 nautical miles).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Distance Traveled&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now that we have our radius, we can calculate how long it will take us to turn 180°. This part is the same equation as before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;48195 = 15341\pi&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Giving us 48195 meters (26 nautical miles).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Duration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Distance divided by velocity gives us duration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;t = \frac{d}{v}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In our case:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;191.2\ seconds = \frac{48195}{490 \times 0.514444}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it'll take 3 minutes 11 seconds to complete the turn.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Downward Acceleration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The last value we need before we can calculate the altitude lost in the turn is to calculate how fast we're going to be accelerating towards the ground in this turn. Lets first calculate the upward portion of our lift vector:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;a_u = g\cos(\theta)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;8.882 = 9.8\cos(25°)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our lift vector is accelerating us upwards at 8.882 m/s/s, while gravity is trying to pull us down at -9.8 m/s/s. That comes out to a net vector of -0.918 m/s/s.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Altitude Lost&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This part requires a little bit of calculus because our descent rate is accelerating. The integral of acceleration is velocity ($v = at$), and the integral of velocity is distance:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;d = \frac{at^2}{2}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, lets calculate the change in vertical distance (altitude):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;-16780 = \frac{-0.918 \times 191.2^2}{2}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, theoretically, our airplane lost 16,780 meters of altitude (55,052 feet). Of course, since we were only 35,000 feet in the air to begin with, this is rather bad news for us. Besides hitting the ground, you would also come close to risking structural damage to the airframe because in this example, 490 knots is considered the speed over the ground, but the total velocity would be higher (about 596 knots) by the end of the turn due to the sink rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll also notice that, assuming we had the altitude to lose in the first place, the turn took longer to complete than in level flight. This is because the magnitude of the lift vector was smaller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can feel free to experiment with other speeds and bank angles, and you could also experiment with higher g turns (simply replace $g$ in the equations with $2g$ or similar). In some cases higher than 1g, you may actually gain altitude, though it's unlikely a 747 would be able to sustain a high-g maneuver which gains altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a quick second example, consider a 2g turn with 80° of bank at 400 knots:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;a_c = 19.302 = 2g\sin(80°) \\&#xA;R = 2193.8 = \frac{400 \times 0.514444}{a_c} \\&#xA;d = 6892 = R\pi \\&#xA;t = 33.5 seconds \\&#xA;a_u = 3.404 = 2g\cos(80°)&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Giving a total altitude lost of 3589 meters (11,775 feet) over 33.5 seconds. However, at the end of the turn, you would have a sink rate of 214 meters (703 feet) per second. That's over 42,000 feet per minute. It would likely be possible to recover from that in the altitude remaining, but it would not be pleasant.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-08-10T04:47:00.540" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8014" PostTypeId="2" ParentId="8012" CreationDate="2014-08-04T21:24:11.960" Score="14" Body="&lt;p&gt;To calculate turn rates, best start with a load factor $n_z$ or roll angle $\Phi$ and calculate all other parameters using these formulas: $$n_z = \frac{1}{cos \,\Phi}$$&#xA;Radius: $$R = \frac{v^2}{g\cdot tan\,\Phi}$$&#xA;Angular velocity (rad/sec): $$\Omega = \frac{v}{R} = \frac{g\cdot tan\,\Phi}{v}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airliner in cruise will fly close to the local maximum lift, so it will not be able to sustain a steep turn. Pulling more than a few percent of 1 g will cause stronger shocks on the upper wing which will cause a steep drag increase and can even stall the airplane. This is called a high-speed stall. Fortunately, things get better extremely quickly when the airplane slows down a little. If it slows down too much, it will, however, enter into a low-speed stall, because both are separated by a small speed range when flying in low density air at high Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give you an idea what load factor is caused by which roll angle, here is a small list:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;    Ω       load factor [g]&#xA;    0°        1.0&#xA;   10°        1.0154&#xA;   20°        1.0642&#xA;   30°        1.1547&#xA;   40°        1.3054&#xA;   50°        1.5557&#xA;   60°        2.0&#xA;   70°        2.9238&#xA;   80°        5.7588&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I would assume that more than 20° bank will not be possible at cruise. Given that the 747 can fly at Mach 0.85, this translates into 500 kt or 258 m/s in 30.000 ft. The radius for this turn will be 18.65 km or 10 miles. Use the inverse of the angular velocity to calculate the seconds per radian: Flying a 180° turn   ($\Omega = \pi$) will take 227 s or three minutes and 47 seconds.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: Bret Copeland inspired me to add one more case. Not as extreme as Terry would fly it, but it gives you a tighter turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above the turn was flown without sink. I assume that the 747 can not produce much more lift without running into compressibility problems, which would increase drag massively. If I am not concerned about losing altitude, I can use the energy gain from sinking for compensating that extra drag, and then the calculation would run like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting from a 1.5g turn with 48° bank, the plane needs to produce 50% more lift, which will only be possible when the pilot accepts heavy buffeting and pitch-down (Mach Tuck). But let's just assume that is possible. I expect that the lift curve will be well past the Mach break, and drag will at least double. Using data from &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/B747PresS07.pdf?q=747&quot; rel=&quot;noreferrer&quot;&gt;this source&lt;/a&gt;, and assuming an aircraft mass of m = 340 t, another P = 9 MW of power are needed per second on top of what the engines supply. This is possible by sinking with $w = \frac{P}{m}$ = 26.6 m/s. This is a flight path angle of $atan(\frac{26.6}{258})$ = 6°. (I would not be surprised if the real number is closer to 10°, but I have no good aerodynamic data available right now).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turn radius is now only 6.11 km and the 180° turn is completed after 74.4 s = 1 minute and 14 s. The altitude loss with the 6° flight path is 1980 m or 6,500 ft. A more precise solution would include the fact that the lift requirement goes down with the cosine of the flight path angle, but for a first-order estimation the numbers here are good enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not exactly treating the airplane as the handbook would suggest it, but the type has &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot; rel=&quot;noreferrer&quot;&gt;survived&lt;/a&gt; &lt;a href=&quot;http://articles.chicagotribune.com/1992-12-20/travel/9204250793_1_passenger-plane-freighters-test-pilots&quot; rel=&quot;noreferrer&quot;&gt;worse treatment&lt;/a&gt; before.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-10T07:15:54.963" LastActivityDate="2014-08-10T07:15:54.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8016" PostTypeId="1" AcceptedAnswerId="8019" CreationDate="2014-08-04T22:38:22.980" Score="20" ViewCount="23147" Body="&lt;p&gt;I'm told that planes can actually stall when the airflow over the wing goes past Mach 1?  Why does this happen and how do you design an aircraft to avoid it?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-08-05T13:57:58.513" LastActivityDate="2019-09-15T20:25:06.383" Title="What is a high speed stall?" Tags="&lt;aircraft-design&gt;&lt;stall&gt;&lt;supersonic&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8017" PostTypeId="2" ParentId="8012" CreationDate="2014-08-05T01:08:56.433" Score="-5" Body="&lt;p&gt;if you are unconcerned with spilling the drinks in Business class you could do a hammerhead or a split-s, although the hammerhead might be a bit rough on the cabin baggage during the rollover (the FA should NOT occupy the rear bulkhead seat directly off the aisle). The radius of either turn would be zero, time would probably be about half a minute with a drop of 10-20,000 feet.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-08-05T01:08:56.433" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8019" PostTypeId="2" ParentId="8016" CreationDate="2014-08-05T07:22:32.660" Score="14" Body="&lt;p&gt;When the velocity of the airflow locally exceeds speed of sound above the wing a shock wave forms and the flow detaches beyond this shock wave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Mach_tuck#mediaviewer/File:Transonic_flow_patterns.svg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6d/Transonic_flow_patterns.svg&quot; alt=&quot;supersonic flow separation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly to stall, the supersonic separation of flow removes the component of lift produced by decrease of pressure on the upper surface of the wing and so the effects are similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I causes reduction of lift and because centre of pressure is about quarter chord on the upper surface, but midchord on the lower, it causes a significant pitch-down moment, which might be impossible to recover even if the post-stall lift is otherwise sufficient to keep the aircraft flying straight. This effect is often called &lt;a href=&quot;http://en.wikipedia.org/wiki/Mach_tuck&quot; rel=&quot;noreferrer&quot;&gt;Mach tuck&lt;/a&gt;. Supersonic planes often have all-moving elevators to have sufficient control authority to compensate for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A difference from normal stall is that after supersonic flow separation the lift remains proportional to angle of attack and so the aircraft continues to behave more or less normally except for the change in trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mach tuck may occur as low as Mach 0.7 depending on aircraft design, because the air moves faster over the wing. It can be delayed by using &lt;a href=&quot;http://en.wikipedia.org/wiki/Swept_wing&quot; rel=&quot;noreferrer&quot;&gt;swept wings&lt;/a&gt;, because the shock waves only form when the air velocity component perpendicular to the wing exceeds speed of sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supersonic aircraft eventually encounter supersonic flow separation, but the lower surface lift is sufficient to balance the aircraft weight at that speed and altitude and the aircraft can continue flying with the upper surface flow separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's not the case with most subsonic aircraft, which for efficiency reasons tend to cruise at altitudes where they have very small margin to stall. As the stall speed increases with altitude while speed of sound slightly decreases with the lower temperature there, the stall speed will eventually equal critical mach number, which creates the &lt;a href=&quot;http://en.wikipedia.org/wiki/Coffin_corner_(aviation)&quot; rel=&quot;noreferrer&quot;&gt;coffin corner&lt;/a&gt; and absolute ceiling for the aircraft. For most civilian transport aircraft the range between stall speed and critical mach number (where drag increases and supersonic flow separation would begin) reduces considerably at cruise altitude, but they usually don't have enough engine power to reach the actual coffin corner.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.183" LastActivityDate="2014-08-05T12:10:52.213" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8020" PostTypeId="2" ParentId="8016" CreationDate="2014-08-05T07:51:01.497" Score="13" Body="&lt;p&gt;Aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375#6375&quot;&gt;stall&lt;/a&gt; when the wing cannot produce enough lift to sustain flight. This can happen for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flow separation due to high angle of attack. The lift curve slope, which is positive and linear at low angles of attack, becomes negative, such that an increase of the angle of attack results in lower lift. This is caused by viscosity effects.&lt;/li&gt;&#xA;&lt;li&gt;Flow separation and heady buffeting due to strong shocks on the wing close to Mach 1. This is caused by Mach effects. In many cases lift loss is not yet critical but buffeting will become uncomfortably severe and dangerous to structural integrity.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The first is a low speed stall, but it can happen at any speed. High speed stalls are the second variety. They can be provoked by&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;flying faster at the same attitude, normally in very thin air and at speeds around Mach 0.8.&lt;/li&gt;&#xA;&lt;li&gt;Or they can be provoked by demanding more lift at the same speed, e.g. by initiating a turn.&lt;/li&gt;&#xA;&lt;li&gt;A third way is by climbing, such that the air gets thinner and colder, and the wing needs a higher angle of attack to produce the same lift as before.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In all cases, the initial flow over the wing was locally mildly supersonic and produced a weak shock. Either by increasing speed (more precisely: The flight Mach number) or angle of attack, the shock becomes stronger and can &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;cause flow separation&lt;/a&gt;, such that the wing produces less lift than before. The aircraft stalls. In case of the U-2, the tail would still work, only the wing would produce less lift, so the plane pitches down and accelerates. Acceleration makes things worse, because now the shocks grow even stronger. Now the pilot is locked into a dive which he cannot end. A lot of fun when a few kilometers below the pilot sees MiG-17s, performing pull-ups from high speed to get close enough to open fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully, the drag increase due to the stronger shocks limits the speed increase, and after dropping for maybe 2km, the air becomes dense enough for the U-2 pilot to successfully stop the dive and start the climb back to the safer, higher altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to avoid this? Generally, this is impossible to avoid altogether, it can only be mitigated. Wing sweep is the most effective way to limit lift loss due to local shocks, but even a highly swept delta wing will have a reduction of its maximum lift coefficient around Mach 1. An optimized airfoil shape helps to push the limit up, but when this new limit is exceeded, the lift loss will be heavier. In the end, most modern aircraft resort to limiting the flight envelope and using an electronic FCS to ensure that the envelope is not exceeded.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-09-15T20:25:06.383" LastActivityDate="2019-09-15T20:25:06.383" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="8021" PostTypeId="2" ParentId="7990" CreationDate="2014-08-05T12:08:44.817" Score="4" Body="&lt;p&gt;The definition of a helicopter as well as other aircrafts is provided in &lt;strong&gt;14 CFR Part 1&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8403e178a4e1d0f8339151fe2529e600&amp;amp;node=14:1.0.1.1.1&amp;amp;rgn=div5&quot; rel=&quot;nofollow&quot;&gt;http://www.ecfr.gov/cgi-bin/text-idx?SID=8403e178a4e1d0f8339151fe2529e600&amp;amp;node=14:1.0.1.1.1&amp;amp;rgn=div5&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Manufacturers may seek clarification from the FAA about these definitions if/when there is a requirement .&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-05T12:08:44.817" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8022" PostTypeId="1" AcceptedAnswerId="8027" CreationDate="2014-08-05T14:06:43.977" Score="42" ViewCount="32729" Body="&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20050816-0&quot;&gt;West Caribbean Airways Flight 708&lt;/a&gt; which crashed in 2005, fell victim when their plane encountered a deep-stall. From my understanding, only certain planes can 'deep-stall'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can pilots recover their plane to recover from a deep stall?&lt;/p&gt;&#xA;" OwnerUserId="3091" LastEditorUserId="14897" LastEditDate="2018-06-17T06:07:56.303" LastActivityDate="2020-03-18T05:58:07.243" Title="What is a 'deep stall' and how can pilots recover from it?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8023" PostTypeId="2" ParentId="8022" CreationDate="2014-08-05T14:29:30.047" Score="9" Body="&lt;p&gt;The article on &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_(flight)#Deep_stall&quot;&gt;stall&lt;/a&gt; in Wikipedia talks of one instance where a B727 recovered from a deep stall by &quot;rocking the plane to higher bank angles&quot; till the nose dropped and normal control response was recovered.&lt;/p&gt;&#xA;" OwnerUserId="3090" LastEditorUserId="1289" LastEditDate="2014-08-05T14:54:25.803" LastActivityDate="2014-08-05T14:54:25.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8024" PostTypeId="1" CreationDate="2014-08-05T15:30:05.783" Score="0" ViewCount="74" Body="&lt;p&gt;After going through this &lt;a href=&quot;http://www.howtogeek.com/194019/yes-you-can-use-electronics-during-takeoff-and-landing-what-you-need-to-know/&quot; rel=&quot;nofollow&quot;&gt;site&lt;/a&gt; I am still not clear as to why do some nations do not allow the use of hand held device's especially  cell phones for making calls or texting but for gaming or reading during take off or landing or throughout the flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;although the difference lies in network usage but still the device is ON and still may cause disturbance to the onboard equipment like navigation or communication. Then what's the point in allowing for gaming or reading throughout the flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen some reports that claim they don't cause disturbance and some say they do.&lt;/p&gt;&#xA;" OwnerUserId="3012" LastActivityDate="2014-08-05T15:30:05.783" Title="Why do some nations allow the usage of hand held devices and some not throughout the landing till the take off" Tags="&lt;safety&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2014-08-06T05:55:58.943" ContentLicense="CC BY-SA 3.0" />
  <row Id="8025" PostTypeId="2" ParentId="8022" CreationDate="2014-08-05T15:36:28.517" Score="16" Body="&lt;p&gt;A deep stall is a stall where the pilot is unable to pitch down due to either loss of clean airflow over the elevator (typical in T-tails) or the canards still producing lift while the wing behind it is stalled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the aircraft the pilot may be able to bank and use the rudder to get the nose down to correct the stall. If possible the pilot may be able to move/ditch cargo to move the Center of Mass forward.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-08-05T15:36:28.517" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8026" PostTypeId="2" ParentId="7982" CreationDate="2014-08-05T18:31:11.857" Score="5" Body="&lt;p&gt;The tilt and the gyroscopic effect cause the helicopter to hover with a slight bank in a no-wind condition, a compromise that is acceptable. It should also be noted that a crosswind can exaggerate the bank, eliminate it, or even cause the helicopter to bank in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In helicopters, the controls are rigged is such a way that when forward cyclic is applied, the helicopter moves forward, likewise for aft, etc.  To accomplish this, the pitch horn is offset 90º to the rotor blade.  The controls still tilt the swash plate in the same direction as the control input is made, but due to the pitch horn placement, the input to the blade occurs 90º earlier in the plane of rotation. The tail rotor as a gyroscope is rather insignificant&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://books.google.co.in/books?id=lTkiuG4RaFIC&amp;amp;pg=PA410&amp;amp;lpg=PA410&amp;amp;dq=gyroscopic+effect+%2B+tail+rotor&amp;amp;source=bl&amp;amp;ots=0t9R_FBArG&amp;amp;sig=pWRaKnWgjGAqkmeePDrmmclx7UA&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=rSHhU7jSBMG0uAS9ioDIDQ&amp;amp;ved=0CD8Q6AEwCQ#v=onepage&amp;amp;q=gyroscopic%20effect%20%2B%20tail%20rotor&amp;amp;f=false&quot;&gt;http://books.google.co.in/books?id=lTkiuG4RaFIC&amp;amp;pg=PA410&amp;amp;lpg=PA410&amp;amp;dq=gyroscopic+effect+%2B+tail+rotor&amp;amp;source=bl&amp;amp;ots=0t9R_FBArG&amp;amp;sig=pWRaKnWgjGAqkmeePDrmmclx7UA&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=rSHhU7jSBMG0uAS9ioDIDQ&amp;amp;ved=0CD8Q6AEwCQ#v=onepage&amp;amp;q=gyroscopic%20effect%20%2B%20tail%20rotor&amp;amp;f=false&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also,  speed decreases all the way from the start of the approach to the hover point, and the power, controlled by the collective-mounted throttle, decreases during the first half of the approach, and then increases during the latter half - as the helicopter nears the hover spot and loses translational lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a stable, no-wind hover everything is in equilibrium. The engine is providing just enough power to keep the main rotor turning at just the right rpm to hold the height over the ground and to keep the tail rotor spinning at just the right angle to counteract the torque of the main rotor. When you push one or the other of the tail rotor pedals forward, you upset this balance and must do something to compensate in order to hold the same hover height.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a hover, the torque of the main rotor tries to turn the fuselage to the right and therefore pressure on the left pedal is required to keep the nose straight. Forward left pedal means the tail rotor blades are biting the air at a greater angle of attack and therefore producing more lift. If you add even more forward left pedal to initiate a left hovering turn, you increase the tail rotor blade pitch angle even more. This requires more power from the main gearbox and, if engine power remains constant, the only way the gearbox can satisfy this increased demand for power from the tail rotor is to allow main rotor rpm to decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail rotor provides horizontal thrust but only to the right (nose left).  The tail rotor counters the torque on the fuselage caused by the engine driving the main rotor&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-05T18:31:11.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8027" PostTypeId="2" ParentId="8022" CreationDate="2014-08-05T18:59:52.003" Score="58" Body="&lt;p&gt;A deep stall or a super stall is a condition where the wake of the wing impinges on the tail surface and renders it almost ineffective. The wing is fully stalled, so the airflow on its upper surface separates right after the leading edge, which produces a wide wake of decelerated, turbulent air. Consequently, the dynamic pressure at the tail surface is much smaller than in unstalled flight, which is the main reason for the reduced effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider this case: The aircraft flies in a nose-up attitude, but on a downward flight path. Consequently, the angle of attack of the wing $\alpha$ is much beyond its normal operating range, causing a fully separated upper surface flow. Due to the T-tail configuration, the wake is hitting the elevator such that all of it is shielded from the regular airflow.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WufBe.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pitching moment of this configuration over angle of attack (blue line) looks something like this. First there is a stable region with a negative gradient at low values of $\alpha$, followed by a minimum when the wing stalls, and then a region with a positive gradient, where the separation unfolds and the tail moves into the wake from above. This region is unstable in pitch, so without control input the aircraft will not stay there, but either pitch down or up until it reaches a stable region again. At high angles of attack follows another stable region with a negative gradient:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/r1g2r.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Note that we have two trim points, one in the regular range of the angle of attack, and one way out to the right. In both cases the aircraft has a stable trim condition, so small disturbances are answered with force changes which will keep the aircraft at one of these points. Between the two, there is another equilibrium point, but here the airplane is unstable. If it pitches up slightly there, the pitch up will accelerate until it reaches the upper trim point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider the control power of the horizontal tail. When it flies in undisturbed air, it can trim a wide range of angles of attack. In the deep stall condition, however, its control power is much reduced, resulting in a much smaller range of trimmable angles of attack. If the lower end of this range is right of the point where the pitching moment crosses into positive values (here at $\alpha$ = 24°), the aircraft cannot escape with elevator deflections!&#xA;&lt;img src=&quot;https://i.stack.imgur.com/5JWlX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that the control power is not sufficient to enter the deep stall with quasi-stationary trim changes. The pilot needs to pitch up quickly and has to overshoot the static trim range in order to cross into the stable region above 30° angle of attack. There, his range of trimmable $\alpha$s is too small to achieve the same overshoot backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get out of this trap needs other changes: Either shift the center of gravity forward, or try to drop one wing. Unfortunately, both the ailerons and the rudder will also be much less effective due to the massive separation and the wake. In a number of cases, even experienced test pilots could not escape this condition.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-06T05:47:54.610" LastActivityDate="2014-08-06T05:47:54.610" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8028" PostTypeId="1" AcceptedAnswerId="8029" CreationDate="2014-08-06T06:49:02.407" Score="21" ViewCount="15781" Body="&lt;p&gt;What is the minimum turning radius of an &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;noreferrer&quot;&gt;SR-71&lt;/a&gt; at Mach 3.2 and an altitude of 80,000 feet? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard that if an SR-71 were to cross the Pacific coast over San Francisco and pull a hard turn to the right, it would return over Seattle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in real-world performance, taking into account things like inlet unstart (failure to capture the engine inlet shockwave in the intake) from too sharp an angle of attack.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="15311" LastEditDate="2017-12-19T20:06:06.120" LastActivityDate="2017-12-19T20:06:06.120" Title="What is the minimum turning radius of an SR-71?" Tags="&lt;aircraft-performance&gt;&lt;sr-71&gt;&lt;reconnaissance-aircraft&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8029" PostTypeId="2" ParentId="8028" CreationDate="2014-08-06T07:12:24.963" Score="13" Body="&lt;p&gt;Please use the equations of &lt;a href=&quot;https://aviation.stackexchange.com/questions/8012/what-does-it-take-to-turn-a-747-around-180-degrees/8014#8014&quot;&gt;this answer&lt;/a&gt;. The numbers might be different, but the physics are the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Thanks to D_S for providing the link to the manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flown with the maximum allowable load factor of 1.5 g at 80.000 ft (48° bank), the turn radius at Mach 3.2 (equivalent to v = 953.3 m/s in 80.000 ft) will be 83.5 km. To be more precise, you will need to add the effects of earth rotation, but for now I leave this away. As you can see, the turn will still need 163 km or 103.7 miles, but not the &lt;a href=&quot;http://www.google.de/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;ved=0CC4QFjAB&amp;amp;url=http%3A%2F%2Fwiki.answers.com%2FQ%2FWhat_is_the_distance_between_Seattle_and_San_Francisco&amp;amp;ei=RtThU4T4IcTMyAPJ5IHQBg&amp;amp;usg=AFQjCNH3ItWUqWs3-hkDcrdXrYeaH5Wvdg&amp;amp;sig2=5RSYVFcl69kA5du0-pZ9NQ&amp;amp;bvm=bv.72197243,d.bGQ&quot; rel=&quot;noreferrer&quot;&gt;distance from San Francisco to Seattle&lt;/a&gt; which is more than 6 times bigger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To turn this around: A circle at Mach 3.2 which has a diameter of 1092 km requires a bank angle of 9.6°. That can hardly be called a turn.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-08-07T13:49:32.167" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="8030" PostTypeId="1" AcceptedAnswerId="8031" CreationDate="2014-08-06T07:51:35.310" Score="2" ViewCount="2741" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NrgdA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could anyone able to tell me the &quot;Landing Since New&quot; Meant? and what is the FC and FH in here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks&lt;/p&gt;&#xA;" OwnerUserId="3095" LastEditorUserId="1696" LastEditDate="2015-02-26T16:37:00.837" LastActivityDate="2015-02-26T16:37:00.837" Title="What do the terms &quot;Landing Since New&quot;, FC, and FH mean on a Landing Gear RDAS?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;aircraft-maintenance&gt;&lt;aircraft-limitations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8031" PostTypeId="2" ParentId="8030" CreationDate="2014-08-06T08:32:24.457" Score="3" Body="&lt;p&gt;Landing Since New - &lt;em&gt;The definition is probably provided in Page 2 of the RAS&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This basically means the number of hours spent Landing from the time the aircraft was brand new . Based on this figure the blades will have to be removed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FH - Flight Hours - Basic unit for measuring length of time in service/before maintenance becomes due. The flight hour (FH) represents one hour of flight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FC - Flight Cycles - One Take Off and Landing &lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-06T08:32:24.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8032" PostTypeId="2" ParentId="8028" CreationDate="2014-08-06T08:47:50.020" Score="19" Body="&lt;p&gt;The Turn Radius of the SR-71 would depend on its speed. The faster it went  the wider its turn radius was. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The SR-71 had a minimum turning radius at altitude of about 80 nautical miles (NM)&lt;/strong&gt; . It was not an airframe limitation but a matter of wing area. At 80,000ft, the air is too thin and the wings too small to allow for much lift to turn with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a turn radius of 80 NM, the SR-71 would cover about 145 miles, taking about 4 minutes in the process of making a 180 degree turn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Details are provided &lt;a href=&quot;http://www.sr-71.org/blackbird/manual/&quot; rel=&quot;noreferrer&quot;&gt;in the SR-71 flight manual handbook&lt;/a&gt;, which is now declassified:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KBHhZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KBHhZm.png&quot; alt=&quot;Fig. 1-9, SR-71 handbook&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="64" LastEditDate="2014-08-07T17:45:34.903" LastActivityDate="2014-08-07T17:45:34.903" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8034" PostTypeId="2" ParentId="8028" CreationDate="2014-08-06T09:29:14.570" Score="4" Body="&lt;p&gt;Considering the current flight status of the SR-71 (retired) it's maximum speed will depend on the tug moving it and the turn radius is probably around 30-40 meters depending on how far the nosewheel pivots.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-08-06T09:29:14.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8036" PostTypeId="1" AcceptedAnswerId="8039" CreationDate="2014-08-06T13:00:43.563" Score="32" ViewCount="8770" Body="&lt;p&gt;I just read an article about a man (who is alledgedly an airplane mechanic) who was a passenger on an airplane that had some mechanical issues. Because there were no 'local' mechanics around, he decided to take matters into his own hands and fix the problem himself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.hln.be/hln/nl/959/Bizar/article/detail/1981598/2014/08/06/Passagier-wil-op-tijd-thuis-zijn-en-herstelt-zelf-defecte-Boeing.dhtml&quot;&gt;Here's the article I read (it's in Dutch though)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icelandmag.com/article/icelandic-air-mechanic-vacation-saved-day&quot;&gt;Here's one in English&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all seems nice but in this day of age where airplane security and regulation is so tight, I wonder if this is possible at all. It also seems to me that by the airplane company is taking a huge risk in letting this &quot;random&quot; person fix this problem. The article obviously oversimplifies a few things, but regardless of that, here's my question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is it possible for a random passenger, who also happens to be an airplane mechanic (working for airline X) to fix an issue on the airplane he happens to be on,&lt;/strong&gt; given that there are no &quot;local&quot; mechanics around (however unlikely that might be)?&lt;/p&gt;&#xA;" OwnerUserId="3101" LastEditorUserId="753" LastEditDate="2014-08-06T14:01:52.020" LastActivityDate="2017-05-18T13:17:02.013" Title="Would a random passenger be allowed to fix a problem with a commercial aircraft?" Tags="&lt;security&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8037" PostTypeId="2" ParentId="8036" CreationDate="2014-08-06T13:42:36.217" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1407333650492&amp;amp;uri=CELEX:32003R2042&quot;&gt;Part M&lt;/a&gt; requires that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Maintenance of large aircraft, aircraft used for commercial air transport and components thereof shall be carried out by a Part-145 approved maintenance organisation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, I don't really see how a company would let a passenger work on an airplane, even with a proper licence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not to mention the passenger would need tools to perform the job and that's not something one carries in his bag on vacation.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="2532" LastEditDate="2014-08-06T14:11:33.357" LastActivityDate="2014-08-06T14:11:33.357" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8038" PostTypeId="2" ParentId="8036" CreationDate="2014-08-06T15:00:29.877" Score="24" Body="&lt;p&gt;The airline &lt;a href=&quot;http://en.wikipedia.org/wiki/Primera_Air&quot;&gt;Primera Air&lt;/a&gt; is a Danish business that was originally based in Iceland. They have a fleet of 8 Boeing 737s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The passenger Davíð Aron Guðnason is an Icelandic air mechanic. He is &lt;a href=&quot;http://www.icelandmag.com/article/icelandic-air-mechanic-vacation-saved-day&quot;&gt;reported&lt;/a&gt; as saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“I spoke to the captain on board and he put me through to the airline’s head mechanic who’s based in Stockholm, Sweden. He told me that there was a problem with the plane’s starter valve – which is relatively easy to fix. It only took me about thirty minutes to repair,” Davíð Aron explained in an interview with news website Vísir.is yesterday.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So he wasn't a random passenger, he was a passenger with appropriate qualifications who was in contact with the head mechanic of the airline's approved maintenance organisation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To speculate a little, it seems reasonable to suppose that the maintenance organisation take legal responsibility for the repair. There is probably no legal requirement that all mechanics be direct employees of the maintenance organisation, so long as they ensure the mechanic has the required skills and qualifications. Given the airline's history it is possible that the airline's head mechanic, or one of his colleagues, knew Guðnason and/or was easily able to check with Guðnason's employer.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-06T15:05:31.060" LastActivityDate="2014-08-06T15:05:31.060" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8039" PostTypeId="2" ParentId="8036" CreationDate="2014-08-06T19:06:28.650" Score="110" Body="&lt;p&gt;I happen to have personal knowledge of this particular case. I was in that airplane, too, seated two rows away from him. I'm also a former pilot and was naturally very interested in what happened, so I asked him some questions during the flight back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He had worked as service mechanic for this company before, servicing their planes in Iceland. Their technical staff and the pilot of this plane already knew him, which made things easier.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tools and parts were available at the airport in Alicante, but no qualified technician certified for this type of aircraft. The technical staff of the airline contacted his boss in Iceland by phone, who agreed to sub-contract him to the airline for the duration of the repair and pay him overtime for the work.&lt;br&gt;&#xA;They faxed a copy of his certification documents to Stockholm to cover the EASA regulations that require a certified professional doing the repair.&lt;/p&gt;&#xA;" OwnerUserId="2469" LastEditorUserId="11215" LastEditDate="2017-05-18T13:17:02.013" LastActivityDate="2017-05-18T13:17:02.013" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8040" PostTypeId="1" CreationDate="2014-08-06T20:22:12.957" Score="1" ViewCount="980" Body="&lt;p&gt;Is it possible to fly 100 kilometers with a propeller driven aircraft? and if not what is the limit of a propeller driven aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3106" LastEditorUserId="1696" LastEditDate="2016-07-06T21:40:47.930" LastActivityDate="2016-07-06T21:41:13.227" Title="What is the upper altitude limit for propeller driven aircraft?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2014-08-06T21:37:17.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="8041" PostTypeId="2" ParentId="8040" CreationDate="2014-08-06T21:00:46.793" Score="3" Body="&lt;p&gt;The altitude 100 km is also known as the &lt;a href=&quot;http://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kármán line&lt;/a&gt;. It is also called the 'edge of space'. No aircraft can fly higher than this line. Because of the sparseness of the atmosphere they would have to go so fast in order to generate lift that they would reach orbital velocity. Therefore they would be spacecrafts, and not aircrafts.&#xA;As you can see it's a theoretical limit, in practice aircraft fly a lot lower than this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in effect, no it's not possible for a propeller driven aircraft to fly above 100 kilometers altitude, but this is also true for any other kind of propulsion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;About your other question, I believe it's already answered quite nicely here: &lt;a href=&quot;https://aviation.stackexchange.com/questions/7691/how-high-can-propeller-airplanes-fly?rq=1&quot;&gt;How high can propeller airplanes fly?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3067" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-07-06T21:41:13.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8043" PostTypeId="2" ParentId="8030" CreationDate="2014-08-07T04:41:06.823" Score="3" Body="&lt;p&gt;&lt;strong&gt;Landing Since New&lt;/strong&gt;&lt;br&gt;&#xA;This is the number of times that this nose gear has been used while installed on an aircraft when it landed.  I.e. the number of landings that it has been exposed to since the date that it was manufactured (new).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FC&lt;/strong&gt;&lt;br&gt;&#xA;The number of cycles (takeoffs/landings) that the aircraft from which the nose gear was removed from had at the time that it was removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FH&lt;/strong&gt;&lt;br&gt;&#xA;The number of hours of flight that the aircraft from which the nose gear was removed from had at the time that it was removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the aircraft FC and FH don't really mean much in relation to the nose gear unless it has been installed on that aircraft since the time that they were both new.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-08-07T04:41:06.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8044" PostTypeId="2" ParentId="3519" CreationDate="2014-08-07T19:40:51.713" Score="-2" Body="&lt;p&gt;Diesel engines in GA uses radiator cooling and thus heats the cabin with a water heat exchanger, inherently safer than taking heat directly off the exhaust manifold/pipe.&lt;/p&gt;&#xA;" OwnerUserId="3121" LastActivityDate="2014-08-07T19:40:51.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8045" PostTypeId="2" ParentId="65" CreationDate="2014-08-07T21:14:58.897" Score="3" Body="&lt;p&gt;Runway numbers are given as per their direction on compass. Only difference in compass reading and airport runway numbers is that compass reading may be in 3 figures like 120 or 230 etc, but runway numbers are in 2 digits for universal understanding and ease in understanding without confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is simple: when an aircraft is taking off or landing on a runway that has been assigned, say 09; it will mean that when the aircraft would be ready for take off or coming in for landing, its compass reading should indicate 090 (Last digit is not advised as it is understood as zero)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly if an aircraft coming in to land on, say, runway 25, on lining up with the runway while in the air, the aircraft compass should read 250 degrees. Some airports show single digit as runway number, (like 3 or 7). In such cases a zero is to be added before and after the number. Hence 3 will mean 030 and 7 would mean 070.&lt;/p&gt;&#xA;" OwnerUserId="3123" LastEditorUserId="97" LastEditDate="2014-08-07T21:17:09.683" LastActivityDate="2014-08-07T21:17:09.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8046" PostTypeId="1" CreationDate="2014-08-07T23:23:03.340" Score="26" ViewCount="2285" Body="&lt;p&gt;I know that in accident reports they will typically say the total number of hours the pilot had, but also the total hours &lt;em&gt;in type&lt;/em&gt; and total hours &lt;em&gt;in the last 90 days&lt;/em&gt;.  I know from personal experience that landing an airplane can be a perishable skill (I recently went 60+ days since flying and my landings were not the picture-perfect examples they usually are...don't get me wrong, nothing unsafe, just wasn't proud of them...drifting off centerline, excessive float, etc :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA seems to know this with the 90-day passenger carrying requirement (3 take-offs and landings within 90 days to carry passengers during the day and 3 to a full-stop for night passenger carriage).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this to say flying doesn't seem to be &quot;just like riding a bike - you never forget it.&quot;  But in what sense?  The muscle memory goes? The &quot;seat of the pants&quot; sensation starts to feel foreign?  I know charts can change, regs can change, but do you really &quot;forget how to fly,&quot; or just &quot;lose the touch?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What skills go first, and what is the best way to self-assess your skill quality and mitigate the loss of it?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="100" LastEditDate="2020-04-28T08:05:30.707" LastActivityDate="2020-04-28T09:57:02.190" Title="Piloting as a perishable skill - what skills go first and how to self-assess and mitigate skill loss?" Tags="&lt;general-aviation&gt;&lt;pilot-technique&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8047" PostTypeId="1" CreationDate="2014-08-07T23:32:26.363" Score="7" ViewCount="2203" Body="&lt;p&gt;Consider a situation where there is a Temporary Flight Restriction &lt;a href=&quot;https://en.wikipedia.org/wiki/Federal_Aviation_Regulations#Temporary_flight_restrictions&quot; rel=&quot;nofollow&quot;&gt;(TFR)&lt;/a&gt; due to VIP movement (i.e. the President of the United States is in Los Angeles), and I am based at an airport that is within the TFR.  I'm a VFR pilot and I want to go for a little flight from my airfield that doesn't have a control tower, exit the TFR, and then return later in the afternoon (re-entering the TFR) and land at the same airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would be the procedure to get permission to:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Take off and exit the TFR-covered area (non-towered airport), and  &lt;/li&gt;&#xA;&lt;li&gt;Return to the same field later on a different flight (same&#xA;non-towered airfield)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="132" LastEditorUserId="12720" LastEditDate="2016-03-02T14:32:29.477" LastActivityDate="2016-03-02T14:32:29.477" Title="What is the procedure for getting permission to operate an aircraft within a pop-up VIP TFR?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;tfr&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8048" PostTypeId="2" ParentId="8046" CreationDate="2014-08-07T23:52:16.897" Score="24" Body="&lt;p&gt;I have no hard data answers to your questions. Perhaps others will. I can, though, offer some personal observations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My last two jobs were at 747 carriers. At the first we had two weeks on, two weeks off. At the second, we had 12 days off a month, which, with a little seniority, you could arrange to have as a block.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me, the first thing to go was my instrument scan, and I used to joke that it took only 4 days of inactivity to lose that. The joking aside, I did notice a slight degradation the first day or two upon returning to work after time off. I should note that my habit was to hand fly the airplane to the first cruise level, and then to hand fly from the top of descent, so I perhaps would notice a bit of degradation more so than those who used the autopilot as soon as possible and until as late as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I retired 15 years ago, and it had been 30 years since I had flown a light single engine airplane when, a few weeks ago, I decided to check out in a Cessna 172. After three sessions, the instructor said he was satisfied. I wasn't and we went out a four time, and he signed me off for my first-ever BFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, I did a little better than I had expected. In one area, landings, I did a worse. The problem was the sight picture I had in my head from 10 years of landing 747s. On the first landing, knowing that I'd want to flare high, I delayed rounding out until my gut way saying, &quot;if you don't flare, you will crunch the airplane.&quot; When I started the flare, the instructor said, &quot;No, you're way too high.&quot; I delayed again, then started again, and the instructor said I was still too high.&quot; I delayed again, then absolutely had to start again, at which time the instructor said something like, &quot;Well, you're still high but go ahead.&quot; That landing was followed by three sessions of nothing but takeoffs and landings. Each session I improved, but, frankly, I have yet to get a really good landing. My next session will be solo and will be nothing but takeoffs and landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, for me at least, I conclude that we don't forget how to fly, but we definite do lose the touch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After I get the solo takeoff and landings session in, I'm going to go out with the instructor and shoot a couple of ILSs. I'm expecting my instrument scan to be terrible.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-08-08T06:21:13.367" LastActivityDate="2014-08-08T06:21:13.367" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8049" PostTypeId="1" AcceptedAnswerId="8061" CreationDate="2014-08-08T00:31:11.347" Score="36" ViewCount="35224" Body="&lt;p&gt;I'm told that in order to be more maneuverable fighter jets are designed in a way that makes them impossible for a human to control without the help of a flight computer.  Is this actually true?  Would a modern fighter (like an &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot;&gt;F-22&lt;/a&gt; or &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Sukhoi_Su-35&quot;&gt;Su-35&lt;/a&gt;) crash if the stability computers died?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, if this is true, what design techniques are making them unstable and how do they help with maneuverability?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="15311" LastEditDate="2018-06-10T14:47:44.127" LastActivityDate="2019-01-16T21:11:58.787" Title="Are fighter jets designed to be so inherently unstable that a human can't fly one unassisted?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;aircraft-systems&gt;&lt;flight-controls&gt;&lt;avionics&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="8050" PostTypeId="2" ParentId="8049" CreationDate="2014-08-08T01:00:47.153" Score="16" Body="&lt;p&gt;Yes, the first such airplane was the F-16.  It was designed as inherently aerodynamically unstable, which allows it to respond superbly in combat.  This was made possible in that it is a fly-by-wire aircraft.  Maneuverability is increased, because by definition it is the ability to change states.  Stability is the resistance to change.  The more stable you are, the harder it is to turn/pitch quickly in a dynamic situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, a pilot would not be able to land these aircraft if the fly-by-wire systems became inoperative.  There are instances where F-16 pilots have lost their computer and have died because of Pilot Induced Oscillations - the condition where the pilot isn't correcting for their aircraft's instability at a rate fast enough to maintain control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other such unstable aircraft are the B-2, F-22, F-35, Eurofighter, etc.  All modern fighters need to be inherently unstable to be competitive.&lt;/p&gt;&#xA;" OwnerUserId="302" LastEditorUserId="302" LastEditDate="2014-08-09T04:15:20.363" LastActivityDate="2014-08-09T04:15:20.363" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8051" PostTypeId="1" AcceptedAnswerId="8053" CreationDate="2014-08-08T01:35:54.810" Score="45" ViewCount="39466" Body="&lt;p&gt;I know that airport windsocks are calibrated to reach full erection at a particular wind velocity. At half that speed, the first half of the windsock should be erect and the second half should droop sorrowfully. At one third the speed it will be one third, and so on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trouble is that not all windsocks are calibrated the same way. &lt;strong&gt;How do I find out what wind velocity will bring my airport windsock to a fully erect state?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="1046" LastEditDate="2014-08-08T16:15:41.130" LastActivityDate="2016-07-26T14:12:49.997" Title="My windsock is erect, what does this mean?" Tags="&lt;airport&gt;&lt;weather&gt;&lt;airport-markings&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8052" PostTypeId="2" ParentId="8051" CreationDate="2014-08-08T02:26:26.433" Score="13" Body="&lt;p&gt;According to the FAA, &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/150_5345_27e.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory Circular 150/5345-27E&lt;/a&gt;, dtd 26 Sep 2013, Paragraph 3.2.2,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;3.2.2 Dimensions&lt;/p&gt;&#xA;&lt;p&gt;The taper or the fabric windsock from the throat to the trailing end must be designed to cause the&lt;br /&gt;&#xA;windsock to fully extend when exposed to a wind of 15 knots (28 km/hr or 17 mph).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The paragraph, 4.2.6 Windsock Extension gives the variance of wind speed allowed which should still cause a full extension of the wind sock, but that paragraph appears to need editing to put in the starting values for mph and km/hr, 17 and 28 respectively, which are indicated above.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;4.2.6 Windsock Extension.&lt;/p&gt;&#xA;&lt;p&gt;Test the windsock to assure that it extends fully when subjected to a wind of 15 (+2,-1) knots (+3.7,-1.8) km/hr or (+2.3,-1.2 mph) ).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, for instance, the sock should be fully extended from 15.8 mph through 19.3 mph.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-08T20:08:42.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8053" PostTypeId="2" ParentId="8051" CreationDate="2014-08-08T03:02:05.777" Score="54" Body="&lt;p&gt;Windsocks come in various sizes and speeds, but an FAA Standard Wind Sock aligns with the wind at 3 knots, and is fully extended at 15 knots &lt;a href=&quot;https://aviation.stackexchange.com/a/8052/64&quot;&gt;like CGCampbell pointed out&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical wind sock (at least around here) looks something like this:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6kUsD.jpg&quot; alt=&quot;Wind Sock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stripes are actually useful:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The first stripe indicates a 3-knot breeze&lt;br&gt;&#xA;(The wind sock has turned and aligned with the wind - usually you should look for an anemometer near the wind sock to determine if there's any appreciable wind because often the first segment is held open by the frame.)&lt;/li&gt;&#xA;&lt;li&gt;The second stripe is ~ 6 knots&lt;/li&gt;&#xA;&lt;li&gt;The third stripe is ~ 9 knots&lt;/li&gt;&#xA;&lt;li&gt;The fourth stripe is ~ 12 knots&lt;/li&gt;&#xA;&lt;li&gt;The last stripe is 15 knots or higher&lt;/li&gt;&#xA;&lt;li&gt;If the windsock is missing you probably shouldn't be at the airport.&lt;/li&gt;&#xA;&lt;li&gt;If the pole is missing you're probably on your way to Oz.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(You can actually get a far more precise estimation if you're willing to do some trigonometry, but this works well enough for most purposes.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-08-08T03:02:05.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8054" PostTypeId="2" ParentId="8049" CreationDate="2014-08-08T03:25:19.363" Score="5" Body="&lt;p&gt;Instability in pitch lowers trim drag for an aircraft with a tail.  Stability refers to the relative positions of the center of lift (cl) and center of gravity, (cg).  When the cg is ahead of the cl (stable) an aircraft that stalls can fall forward, increasing speed and recovering.  When cl is ahead of cg this will not happen.  However, when cl is ahead of cg the tailplane produces lift.  When cg is ahead of cl (unstable), the tailplane produces a downward force, lowering efficiency.  For a canard, stability lets both surfaces produce lift.  However, the canard fighters tend to be unstable in order to increase pitch rate and lower supersonic drag.  At supersonic speeds cl moves backwards meaning the canard would have to shoulder a larger part of the burden of lifting the aircraft.  Since the canard is a less efficient lifting surface than the wing, this is undesirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll add that as a fighter goes supersonic it goes from unstable to stable for both canards and tails.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="2923" LastEditDate="2014-08-08T03:37:58.407" LastActivityDate="2014-08-08T03:37:58.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8055" PostTypeId="1" AcceptedAnswerId="8242" CreationDate="2014-08-08T05:48:57.507" Score="17" ViewCount="2202" Body="&lt;p&gt;I came across this picture of a FedEx McDonnell Douglas DC-10 equipped with an anti-missile defense system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7txOT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Fe-dc10-N357FE-071008-02-16.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikimedia.org&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the picture description:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FedEx became the first U.S. carrier to equip its aircraft with an anti-missile defense system in 2006. The gray oval Northrop Grumman Guardian pod can be seen on the belly of this FedEx MD-10 between and just aft of the main landing gear.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does this system work? Does this successfully work in countering all types of missiles? Can it be reused over multiple missile strike incidents? Are all commercial airplanes compatible with this system? Is it economical for a major airline to fit all of its fleet with this system?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="15311" LastEditDate="2018-06-04T17:53:12.673" LastActivityDate="2018-11-07T22:38:11.127" Title="How does the Guardian counter-MANPADS system work?" Tags="&lt;military&gt;&lt;aircraft-systems&gt;&lt;equipment&gt;&lt;missiles&gt;&lt;sensors&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8056" PostTypeId="2" ParentId="8055" CreationDate="2014-08-08T07:25:13.343" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_Guardian#Description&quot; rel=&quot;nofollow&quot;&gt;wikipedia has a brief description&lt;/a&gt; of the workings of it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Guardian is designed to operate autonomously, without input from the&#xA;  flight crew. An array of sensors detects a missile approaching the&#xA;  aircraft and passes this information to an infrared tracking camera.&#xA;  The system's computer analyses the input signals, to confirm that the&#xA;  threat is real, and then directs a beam of an eye-safe infrared laser&#xA;  at the incoming object. The laser is intended to introduce a false&#xA;  target into the missile's guidance system, causing it to turn away&#xA;  from the aircraft. The detect-track-jam process lasts for two to three&#xA;  seconds. The system then automatically notifies the pilot and air&#xA;  traffic control that a threat has been jammed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From this I can deduce that it will only work infrared targeting systems. It is fully reusable as long as the laser isn't damaged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The unit weighs 250 kg and costs a million dollars, and the manufacturer estimates that the costs can be offset if the ticket price raises a single dollar.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-08-08T07:25:13.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8057" PostTypeId="2" ParentId="8055" CreationDate="2014-08-08T07:51:33.387" Score="11" Body="&lt;h2&gt;How does this system work?&lt;/h2&gt;&#xA;&lt;p&gt;Guardian is basically a Directional Infrared Counter Measures (DIRCM). By using an infrared laser (and an optical parametric oscillator to generate a second IR Band wavelength)  the Guardian jams the IR seekers of incoming Infrared missiles through their sensor apertures.&lt;/p&gt;&#xA;&lt;h2&gt;Does this successfully work in countering all types of missiles?&lt;/h2&gt;&#xA;&lt;p&gt;No, it doesn't. Against Imaging Infra-Red (IR) missiles and missiles with Additional Detector Wavelengths (e.g LWIR) DIRCM will not work.&lt;/p&gt;&#xA;&lt;p&gt;DIRCM systems like Guardian are completely ineffective against radar-guided missiles like  9М38M1 fired by systems like BUK-M2.&lt;/p&gt;&#xA;&lt;p&gt;Work is now underway in developing Fibre Laser DIRCMs that can counter those missiles which present day DIRCMs are unable to counter.&lt;/p&gt;&#xA;&lt;h2&gt;Are all commercial airplanes compatible with this system?&lt;/h2&gt;&#xA;&lt;p&gt;Virtually all models of Airbus and Boeing can be fitted with a DIRCM Pod like the Guardian.&lt;/p&gt;&#xA;&lt;h2&gt;Is it economical for a major airline to fit all of its fleet with this system?&lt;/h2&gt;&#xA;&lt;p&gt;No. This is an extremely expensive technology, so a majority of airlines will not be able to afford this. Remember, they have to fit this DIRCM pod in not just one or two aircraft but more than a dozen aircraft.&lt;/p&gt;&#xA;&lt;p&gt;The most important thing to remember is that if the anti-missile defense system is overwhelmed by a salvo of missiles there is very little that it can do.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-11-07T22:38:11.127" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="8059" PostTypeId="2" ParentId="8051" CreationDate="2014-08-08T10:40:29.040" Score="7" Body="&lt;p&gt;The main function of the  windsock is to show from which direction the wind blows. The faster the wind blows, the straighter and more horizontally the wind extends. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per FAA standards a 15-knot (28 km/h; 17 mph) wind will fully extend the properly functioning windsock. A 3-knot (5.6 km/h; 3.5 mph) breeze will cause the properly functioning windsock to orient itself according to the wind.  If the windsock has blown away, the wind is greater than the 75 knot design limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5345_27e.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5345_27e.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Windsocks are accurate only within a small radius&lt;/strong&gt;. In those airports where there is  only one windsock and it's alongside the midpoint of the runway, the only thing of which you can be certain , is that, the wind at either end of the runway  will NOT  necessarily match. This explains  why  many airports have windsocks at both ends of the runway. The sock in the middle tells traffic which runway to use, but the windsock at the end of the runway tells the pilot what to expect on approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the correspondence between wind speed and degree of extension and straightening will varies from one model to another. &lt;strong&gt;You can calibrate the  windsock with the help of a  anemometer.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After installing the windsock on the ground , use the anemometer to calibrate the shape and orientation of the windsock to specific wind speeds. The anemometer (wind meter) should be held at  the same height as the windsock’s larger opening . Point it into the wind and  record the  wind speed reading. &lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="1467" LastEditDate="2016-07-26T14:12:49.997" LastActivityDate="2016-07-26T14:12:49.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8060" PostTypeId="1" CreationDate="2014-08-08T13:07:10.070" Score="5" ViewCount="2273" Body="&lt;p&gt;Where can I download the flight plan data around the world, so that I have analyze their route?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they provided freely?&lt;/p&gt;&#xA;" OwnerUserId="3127" LastEditorUserId="97" LastEditDate="2014-11-02T00:56:43.150" LastActivityDate="2014-11-02T00:56:43.150" Title="Where can I download the flight plan data around the world?" Tags="&lt;flight-planning&gt;&lt;website&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8061" PostTypeId="2" ParentId="8049" CreationDate="2014-08-08T15:54:01.440" Score="49" Body="&lt;p&gt;My short answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Stability is reduced by shifting the center of gravity aft.&lt;/li&gt;&#xA;&lt;li&gt;Shifting it past the neutral point makes the airplane unstable, so movements away from the trimmed state are accelerated. This increases maneuverability.&lt;/li&gt;&#xA;&lt;li&gt;Flight computers are multiple redundant, if one dies the others take over.&lt;/li&gt;&#xA;&lt;li&gt;Slow unstable airplanes can be flown by a human pilot, but not fast unstable airplanes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the long answer, let me first clarify terms:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static stability is the tendency of a system to return to it's old state after being disturbed. Take a pendulum: If you pull it to one side, it will return to the middle. Eventually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dynamic stability is the tendency of an oscillating system for the oscillations to die down over time. Take the same pendulum: It will swing from side to side, and  friction will ensure this happens with ever smaller amplitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we need to add dimensions, all three of them: Pitch, roll and yaw. An airplane can be stable in one dimension and unstable in a different one. I understand your question such that you ask about the static pitch stability (or longitudinal stability) of fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wright Flyer was longitudinally unstable (see &lt;a href=&quot;http://authors.library.caltech.edu/21217/1/CULaiaawfp84.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; for more). Once aircraft designers learned that aircraft can be made to fly stable, and learned that this is of immense benefit in pilot training, static stability became a requirement for new aircraft. When war in Europe broke out, the British forces were equipped with a superb &lt;a href=&quot;http://en.wikipedia.org/wiki/Royal_Aircraft_Factory_B.E.2&quot; rel=&quot;noreferrer&quot;&gt;training aircraft&lt;/a&gt;, but it was so stable that it took effort and time to convince it to change course. They were shot down in droves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From now on, low stability was a prime requirement for fighters and aerobatic aircraft. Static stability is proportional to the control forces (more precisely: To the hinge moment of the respective control surface), so reducing stability gave pilots more response for the same effort. Longitudinal static stability is measured as the relative distance between neutral point (NP) and the center of gravity (CG). See &lt;a href=&quot;https://aviation.stackexchange.com/questions/3902/why-is-managing-cg-centre-of-gravity-important-for-aircraft/3927#3927&quot;&gt;here&lt;/a&gt; for more. Longitudinal static stability is achieved by placing the CG ahead of the NP. Shifting the CG back gives you a more responsive airplane, but also one which is more easily disturbed by gusts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the design technique you asked about. Pretty simple, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you shift the CG aft of the NP, stability is lost and the airplane will increase deviations from the trimmed state. This can be helpful if you want large angle changes, and quickly. An unstable aircraft only needs a small kick and will do the rest of the maneuver all by itself. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is how it helps in maneuverability. But it is even more helpful to reduce the inertias, especially around the roll axis, for a faster response. That is why all combat aircraft have their engines close to the center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, negative stability is not acceptable when you need to take your hands off the stick to get a map out or to pee on a long flight. So without computer control, the limit was a CG position near, but not aft of the NP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With supersonic aircraft, things got more complicated. Now the aircraft operates in two flight regimes, one where lift acts at the quarter chord of the wing and one where it acts at mid-chord. Aircraft with low static stability become very stable in supersonic flight, and the tail surface has to create a high down-force so that the sum of all lift stays where the CG is. Creating lift always incurs a drag penalty, and in supersonic flight it has to be payed twice: One for the excess lift on the wing (which is needed to compensate for the tail's down-force) and one for the down-force on the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a flight control computer offers the possibility to allow the pilot to let go of the stick without the aircraft going off course. Now the stick does not command elevator deflection, but pitch rate, and the CG can be moved back from maybe 12% of MAC (mean aerodynamic chord) to -2%. If you compare the wing areas of stable and unstable jets (Jaguar and Mirage F-1 are prime examples), you will see how much is achieved just by going back with the CG by a few percent of wing chord.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/MrCRN.png&quot; alt=&quot;conventional Jaguar and CCV version&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conventional &lt;a href=&quot;https://en.wikipedia.org/wiki/SEPECAT_Jaguar&quot; rel=&quot;noreferrer&quot;&gt;SEPECAT Jaguar&lt;/a&gt; and CCV version (picture from Ray Whitford's Fundamentals of Fighter Design). Both configurations have the same airfield and combat performance!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can a human still fly such an aircraft? In glider competitions, the more daring pilots fly with relaxed static stability and have no problem to keep the aircraft under control. Even the Wright brothers could handle their unstable airplane, and handling improved when they moved the CG further back (If you want to know why, please post a new question. This answer is getting too long already!). However, the speed of an aircraft's pitch response is proportional to flight speed (and inverse to the pitch moment of inertia), so faster aircraft are harder to control. You can compare dynamic pressure with the stiffness of a spring: A stiffer spring moves the eigenfrequency of a spring-mass system up, and the same is true for the eigenvalues of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_dynamic_modes&quot; rel=&quot;noreferrer&quot;&gt;equations of motion&lt;/a&gt; of an aircraft. Given that the reaction time of a good pilot is at least 0.1 s (and more if he/she is tired), it is impossible to counteract motions with frequencies of more than a few Hertz. The lag means that the reaction comes too late and will support the motion. See &lt;a href=&quot;https://www.youtube.com/watch?v=faB5bIdksi8&quot; rel=&quot;noreferrer&quot;&gt;this YouTube clip&lt;/a&gt; how that works out in practice. This crash was due to wrong signal gains, not a classic instability (after all, the flight computer was still working, but produced too strong elevator deflections).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would venture to say that a human can still barely fly an unstable jet at low speed (after all, Tom Morgenfeld almost got the YF-22 under control), but once he firewalls the throttle, he will be always behind the plane, and will crash it soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Size helps: Bigger planes have lower eigenfrequencies, and light, big vehicles are easy to control, regardless of stability. All Zeppelins were completely unstable in yaw and above the critical airspeed of an airship (again, please ask for a more detailed answer on this aspect) also in pitch, but with one person each for the vertical and the horizontal control surfaces, and enough people on board to rotate them after 2 - 4 hours, nobody felt the need to make Zeppelins naturally stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one computer dies, the others take over. Most unstable configurations have four parallel computers which cross-check their result to catch any malfunction. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Dassault_rafale&quot; rel=&quot;noreferrer&quot;&gt;Dassault Rafale&lt;/a&gt; uses only three, but adds safety by clever algorithms for checking the results.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-01-16T21:11:58.787" LastActivityDate="2019-01-16T21:11:58.787" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="8062" PostTypeId="1" AcceptedAnswerId="8066" CreationDate="2014-08-08T18:09:32.340" Score="8" ViewCount="1311" Body="&lt;p&gt;I am training in an Ercoupe 415-C (C-85) that has no rudder pedals. I've read various stories about people taking a checkride in such an aircraft having a restriction on the license and having to take another checkride in a different aircraft to have the restriction removed. I've also seen this referenced as a myth that does not happen in real practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My questions:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does this restriction really exist, or is it a myth?&lt;/li&gt;&#xA;&lt;li&gt;Does it depend on the examiner?&lt;/li&gt;&#xA;&lt;li&gt;Does it apply to sport pilot (where I would have to have an endorsement for another model anyways), or just private?&lt;/li&gt;&#xA;&lt;li&gt;Would I have to take another checkride to have it removed, or could&#xA;it be removed with a CFI's endorsement?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3131" LastEditorUserId="1696" LastEditDate="2015-02-25T22:59:42.183" LastActivityDate="2015-02-25T22:59:42.183" Title="Would there be a restriction on my Sport Pilot license if I do my checkride in an aircraft without rudder pedals like the Ercoupe?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8063" PostTypeId="1" AcceptedAnswerId="8065" CreationDate="2014-08-08T18:23:20.547" Score="8" ViewCount="636" Body="&lt;p&gt;Does one accident report overrule the other or would there be two possible outcomes for the disaster?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/EgyptAir_Flight_990&quot;&gt;EgyptAir Flight 990&lt;/a&gt; had the NTSB and the ECAA investigate and produced two different reports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/SilkAir_Flight_185&quot;&gt;SilkAir Flight 185&lt;/a&gt; had the NTSB and the NTSC investigate and also produced two different reports.&lt;/p&gt;&#xA;" OwnerUserId="3091" LastActivityDate="2015-02-25T15:08:28.957" Title="What happens when more than one agency investigates a plane crash?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8065" PostTypeId="2" ParentId="8063" CreationDate="2014-08-08T19:29:47.303" Score="14" Body="&lt;p&gt;Two reports are published and everybody is free to believe whichever they choose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to ICAO rules the (investigation board&lt;sup&gt;1&lt;/sup&gt; of) country of occurrence (or country of operator if it happens over international waters) leads the investigation and (investigation boards of) country of operator, country of aircraft registration and country of aircraft manufacture are asked to take part in the investigation&lt;sup&gt;2&lt;/sup&gt;. So it is expected that the investigators from country where the accident happened will publish the official report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But some investigators may choose to publish their own report if agreement about the probable cause is not reached. Since even the official report does not have any legal effect (the investigation boards don't have any legal power), so it does not really matter much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An accident report identifies factors that contributed to the accident and suggests improvements to safety practices to reduce risk of the accident reoccurring. But whether the recommendations are implemented depends on aviation authorities&lt;sup&gt;3&lt;/sup&gt;, which are &lt;em&gt;separate&lt;/em&gt; governmental bodies with legislative power. And they decide which recommendations they will incorporate into the legal rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course each such authority only has power over that country. So while the accident is investigated just once (even when multiple reports are published, the investigation is joint effort, just the investigators don't agree on the conclusion), the rules may be implemented differently in different countries. ICAO tries to coordinate, but it does not have any legal powers itself either. So it is up to the aviation authorities to choose which report they believe more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assigning blame is explicitly &lt;em&gt;not&lt;/em&gt; purpose of the investigation according to ICAO rules. A criminal trial or civil litigation may be started about the accident by complaint from police, state attorney or damaged person, in which case the investigation report will likely appear as expertise in the court, but if there is not agreement between the investigators, it is again up to the court to decide which explanation it believes most.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the investigators not agreeing is rare in practice. Usually the investigation continues until they get something they can agree on; for several years if needed. Suspected intentional crashes by pilot (which is both cases you mention) seem to be the main exception as there may be political reasons why the leading investigators (from the same country the pilots were) don't want to accept that resolution.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;Investigation board in USA is NTSB, in Canada TSB (the most rigorous investigation board in the world (or at least they very carefully collect and report even the smallest incidents, see &lt;a href=&quot;http://avherald.com/h?article=45483425&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;)), in UK AAIB, in France BEA etc.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;&lt;sub&gt;It is not strictly necessary, but it is the usual setup. The country of occurrence handles most investigation on site, country of registration takes care of interviewing operator and maintenance personnel and country of manufacture cooperates with manufacturer on identifying mechanical damage and usually reads the FDR and CVR data as there are only a few labs in the world that do that. Plus some of the large investigation boards may be asked for additional help. And in politically sensitive cases like MH17 additional countries may be involved to reduce risk of manipulation with the results.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;&lt;sub&gt;Aviation authority in USA is FAA. In Europe there is EASA, which coordinates the regulations, and separate authorities in each country that carry out the actual oversight.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="65" LastEditDate="2015-02-25T15:08:28.957" LastActivityDate="2015-02-25T15:08:28.957" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8066" PostTypeId="2" ParentId="8062" CreationDate="2014-08-08T22:25:34.397" Score="8" Body="&lt;p&gt;The restriction you're talking about does exist, but there's no explicit wording for it. It's described in &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/farsbysectlookup/61.45!OpenDocument#_Section1&quot;&gt;FAR 61.45(b)(2)&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An applicant for a certificate or rating may use an aircraft with operating characteristics that preclude the applicant from performing all of the tasks required for the practical test. However, the applicant's certificate or rating, as appropriate, will be issued with an appropriate limitation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One of the most fundamental tasks in the Sport Pilot PTS is &lt;code&gt;maintaining coordinated flight&lt;/code&gt; (you won't find it as a discrete task, but if you look at the PTS the phrase &quot;while maintaining coordinated flight&quot; occurs multiple times), and an Ercoupe without rudder pedals relieves the applicant of that responsibility because the aileron/rudder interconnect basically does it for you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure exactly how this works for Sport Pilots, but as you cannot demonstrate to the examiner that you can &quot;maintain coordinated flight&quot; they could reasonably apply the same restriction to your Sport Pilot certificate as they would to a Private Pilot certificate (&quot;Limited to aircraft without rudder pedals&quot;).  You would need to demonstrate to a DPE or Examiner that you can operate an aircraft with rudder pedals at some later date to remove the restriction (it is a restriction on the &lt;em&gt;certificate&lt;/em&gt; so the only way to remove it is to have the certificate amended/reissued/replaced).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The easiest way to avoid the entire issue is to prepare for and take your practical test in an aircraft with rudder pedals. You can do everything in the Ercoupe and then switch to the Cub for a week to brush up on systems and polish your maneuvers in that plane and get used to using your feet.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-08T22:25:34.397" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8067" PostTypeId="2" ParentId="8047" CreationDate="2014-08-08T23:40:14.133" Score="3" Body="&lt;p&gt;It depends on the TFR, sometimes simply communicating with the ATC that controls that area will be sufficient, other times you might need to have a flight plan and a clearance, other times you simply might not be able to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NOTAM for the specific TFR that you wish to fly through should have the information you need.  You can also call Flight Service and they can help you accomplish what needs to be done.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-08-08T23:40:14.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8068" PostTypeId="2" ParentId="8046" CreationDate="2014-08-09T05:48:20.250" Score="4" Body="&lt;p&gt;I agree with @Terry, but to add a couple points. If I go without flying for an extended period, some skills that I am rusty on are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Emergency Procedures.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Getting the feel of the airplane again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As far as emergency procedures, if I'm flying everyday I find it beneficial to do a take-off briefing (failed engine before/after lift-off). When I come back from a hiatus of flying, these take-off briefings take a bit to remember and get back in the groove, reaction time is critical. Sometimes I will practice forced-landings when landing at home (when proficient, it's no big deal hitting your mark). When I'm rusty - it's a bit more sloppy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as getting the feel of the airplane again, some things I notice are landing too fast, maintaining coordination takes a bit more work (muscle memory). Basically, just general flying skills.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to mitigate the loss is to fly at least once a week, even if it's just a trip around the pattern, that will help tremendously.&lt;/p&gt;&#xA;" OwnerUserId="553" LastActivityDate="2014-08-09T05:48:20.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8069" PostTypeId="2" ParentId="8060" CreationDate="2014-08-09T12:02:28.147" Score="2" Body="&lt;p&gt;For historical FAA IFR flight plan data, you can get it from www.flightaware.com.  They show five minute delayed, and with a free registered account you can get access to the last 90 days worth of data.  You can pay for data older than that and I believe in different data formats. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not aware of a similar source for other parts of the world. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-08-09T12:02:28.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8071" PostTypeId="2" ParentId="65" CreationDate="2014-08-09T13:32:10.517" Score="11" Body="&lt;p&gt;&lt;strong&gt;Runways are numbered based on compass heading.&lt;/strong&gt; &#xA;(Note that within the US, we use &lt;strong&gt;MAGNETIC heading&lt;/strong&gt;; &lt;em&gt;this is not necessarily the case in other countries!&lt;/em&gt; (e.g: Canada, which is closer to the north pole, where they use true north to compensate for compass north being off)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Meaning each physical runway is two numbers!)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The heading of the runway is rounded and truncated to the first two digits; For example, a runway with a heading of 093 degrees becomes runway 9. (Runway 27 from the opposite end).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you may ask, &lt;strong&gt;&lt;em&gt;what if there are 2 parallel runways?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One becomes runway 9L (left) and the other becomes runway 9R. A third runway would cause one to become 9C (center).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what if there are &lt;em&gt;MORE&lt;/em&gt; runways on the same heading? (Such as the 4 at Harstfield-Jackson International Airport in Atlanta?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the airports will typically change the number of the runways by one, even though the actual heading of the runway may be no different! (For example, you would now have runways 8L, 8R, 9L, and 9R that are all parallel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't this cause problems with pilots not knowing the actual heading of the runway though?&#xA;&lt;em&gt;(Remember that the headings are rounded, and based on magnetic (less accurate) headings!)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the pieces of information about airports that is published on charts and such is the actual heading of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Grass runways are suffixed with a G (E.g. 12G), although since a pilot usually isn't going to have any trouble identifying a grass runway the G is not usually marked. I can't speak to the numbering of water runways; I have limited experience with amphibious aircraft, and I find it highly implausible that they paint the runway numbers! ;)&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="3048" LastEditDate="2014-08-09T16:19:20.960" LastActivityDate="2014-08-09T16:19:20.960" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8072" PostTypeId="2" ParentId="8055" CreationDate="2014-08-09T13:54:56.883" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it economical for a major airline to fit all of its fleet with this system?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That depends entirely on the airline. If an airline operates only in areas where MANPADS attacks are common, then it might make economic sense to fit countermeasures. On the other hand, if some or all of the airline's planes spend their whole lives within, say, the USA, Canada or the European Union then, at the moment, it is not economical to fit even one aircraft with an anti-MANPADS system since nobody is currently firing MANPADS at planes in those areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that FedEx has this device on only a tiny proportion of its fleet: the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_Guardian&quot; rel=&quot;nofollow&quot;&gt;Wikipedia article on Guardian&lt;/a&gt; mentions them installing it on nine aircraft.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-08-09T13:54:56.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8073" PostTypeId="1" AcceptedAnswerId="8074" CreationDate="2014-08-10T02:03:47.813" Score="27" ViewCount="20464" Body="&lt;p&gt;This question arose during the comments of another question, linked for the curious:&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8012/what-does-it-take-to-turn-a-747-around-180-degrees?noredirect=1#comment14037_8012&quot;&gt;What does it take to turn a 747 around 180 degrees?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the discussion was interesting, (and to avoid congesting the comments of another user's question), I reposted it here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know the answer to this? Official sources/experience are preferred, but I'll take what I can get.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If I was at altitude and suddenly realized we were about to cross into airspace that might get us shot down, I would, smoothly, do 3 things simultaneously: (1) start the nose down to around 25 degrees down, (2) start a roll to a bank angle of 60-80 degrees, and (3) start the power back to idle. At the same time, I'd ask the first officer to deploy the speed brakes, which would give me great roll response. –  Terry&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To which I replied:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;80 degrees of bank would be a bit excessive no? 60 might be reasonable for an emergency turn, but certainly no more in a 747? (G-forces aside) –  HCBPshenanigans&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Terry's reply:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I was thinking of a range because, in an emergency turn, hitting an&#xA;  exact degree of bank would be hard. I would, however, not want to go&#xA;  beyond 90 degrees because of the possible disorienting nature for the&#xA;  flight crew. At 60 degrees, approximately 87% of the wings lift would&#xA;  be turning the airplane. At 80 degrees, about 98% of the lift would be&#xA;  turning the airplane, so the lesser bank would sacrifice 11% of the&#xA;  turning force. I would expect to lose a lot altitude in the turn. I&#xA;  can't think of a reason not use 80 degrees. Pax comfort would be a&#xA;  non-issue. –  Terry&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My most recent response:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Idk if you are a real 747 captain (there are quite a few on here), but&#xA;  iirc many 747 crashes have happened because when the aircraft banks so&#xA;  hard that it loses that much vertical lift, it is very difficult to&#xA;  recover from. In addition, some flight systems might malfunction under&#xA;  these rather extreme conditions. 60, hell even 70, is much steeper&#xA;  than it seems. I seem to remember seeing an episode of that old Air Disaster show about just this. –  HCBPshenanigans&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Edit: What kind of difference would the difference between 60 and 70 or 80 degrees of roll make in time to turn 360 degrees?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2020-06-01T10:08:59.943" Title="What is the maximum safe bank angle of a 747?" Tags="&lt;safety&gt;&lt;aircraft-performance&gt;&lt;boeing&gt;&lt;aircraft-limitations&gt;&lt;boeing-747&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8074" PostTypeId="2" ParentId="8073" CreationDate="2014-08-10T09:36:21.570" Score="26" Body="&lt;p&gt;The descent angle helps to reduce the lift that the wing needs to provide, in two ways. It leads the aircraft into higher density air, where more absolute lift is possible at the same Mach number. That takes a while, but a more immediate effect comes from pointing the aircraft's nose downwards. Then, part of the gravity-induced forces can be counteracted by drag (D in the sketch below). This is similar to a glider, only with much lower aerodynamic efficiency and steeper angles. Terry reduces thrust and opens the speed brakes to avoid overspeeding, so he can dive as steeply as possible, thus reducing lift requirements.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/mkYbA.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Now more of the wing's lift L can be employed for turning the aircraft around. If he wants to achieve a constant sink rate, he still has to produce enough lift to balance weight, but reduced by the cosine of the glide path compared to the level flight condition. At 25° nose down, this is a reduction by 10%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you are concerned about his roll angle. Please note that he wants to create as much sideways component of lift as possible, which will look like gravity to all onboard. At 60° roll angle (I think his 80° are a bit extreme), this works out to twice the normal vertical acceleration, and with the dive actually just 1.8 g, so everyone will feel almost twice the force of normal gravity. With the 80° roll, this will not be a stationary turn and not enough lift will remain to counteract gravity, so the aircraft will accelerate downwards during the turn. It will actually fall out of the sky. When already at Mach 0.85, I would be more careful than Terry, because things get ugly very quickly when Mach goes further up.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Dsy3O.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term $m\cdot\frac{v^2}{R}$ is the centrifugal force which can be afforded by the horizontal component of the lift and which needs to be as big as possible for tight turns (a smaller radius R helps). This is the lift component that Terry needs to pull the aircraft around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we stay with stationary turns (without the &quot;falling out of the sky&quot; part), the maximum bank angle is given by the maximum load factor of the 747. At 400 KEAS, this is just 1.5g, so even with the 25° nose down attitude the maximum bank angle would be 53°. If you fly slightly slower, the load factor goes to 2g (equals 63° in a 25° descent) and tops out at 2.5g at 310 KEAS (68.7° in a 25° descent). Flying at Mach 0.85 in 30.000 ft will produce an equivalent airspeed of 306 kt in normal atmospheric conditions. The precise value varies with the actual flight speed, and the maximum safe bank angle is in the region of 60° to 70°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expanded &lt;a href=&quot;https://aviation.stackexchange.com/questions/8012/what-does-it-take-to-turn-a-747-around-180-degrees/8014#8014&quot;&gt;my answer to the original question&lt;/a&gt;, and I hope in combination with this I can cover your questions. If not, please keep asking!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: I see, now you want to know the time to turn around. All I can do is &lt;a href=&quot;https://aviation.stackexchange.com/questions/2871/how-to-calculate-angular-velocity-and-radius-of-a-turn/3477#3477&quot;&gt;calculate it under the assumption that enough lift is available&lt;/a&gt;, regardless of buffeting. In reality, I doubt that even the 48° case will give you a pleasant ride. All results are for the 30.000 ft case, because at 36.000 ft those higher bank angles will not be cleanly flyable due to compressibility effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 60° the airplane flies with 2g, and with 25° nose down still at 1.8g. The turn rate would be 3.77°/s and 180° would be completed after 48 s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 70° it flies with almost 3g, and with 25° nose down at 2.65 g which is a little outside of the g limits. The turn rate would be 5.98°/s and 180° would be completed after 30 s (plus the time to roll to 70°, which now starts to become important).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 80° case becomes really hypothetical, because even with the 25° nose down attitude the load factor will be 5.2g if flown without sideslip and enough lift to prevent overspeeding. The 747 will be close to breaking apart, but maybe a future aerobatic version can fly this maneuver safely. It will result in a turn rate of 12.35° and need 14.6 s for a 180° turn. I would add at least 4 seconds to bank to 80°, but the turn can be completed within 20 s. Hypothetically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What Terry hinted to when he said he would bank to 80° is not the clean turns I am calculating here, but a dynamic dive where the plane accelerates because not enough lift is left to keep it from falling. To compute this, I would need more aerodynamic data on the 747 and need to employ at least a finite difference algorithm or a lot of paper and pencils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just that much: If the 747 is rolled to 80° but the pilot pulls only as many gs as the aircraft can sustain (due to buffeting I doubt that even 2.5 g are possible), the lift will almost exclusively serve to fly a tight turn, but not enough will be left to counteract gravity. Therefore, the aircraft will slip sideways, and directional stability will turn the nose downwards. This will take a while (I am guessing maybe 12 seconds, really a guess), but the aircraft will pick up speed from the beginning of the maneuver. I am a little more scared of flying faster than Mach 0.85 than Terry is, and the various reports &lt;a href=&quot;http://articles.chicagotribune.com/1992-12-20/travel/9204250793_1_passenger-plane-freighters-test-pilots&quot; rel=&quot;noreferrer&quot;&gt;of 747s going up to Mach 0.98&lt;/a&gt; support his view that a little overspeeding is OK. It is hard for me to guess how much time it needs to become uncomfortably fast, and then a lot of lift will be needed to pull out of the dive. On the other hand, when the airplane is diving, all it needs is a roll and a pull-out to come out at 180° to the previous course. The pull-out will be performed at a much lower altitude, and creating the gs there will not be a problem.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-03-13T14:53:50.710" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8076" PostTypeId="2" ParentId="8073" CreationDate="2014-08-10T13:25:38.283" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;What is the maximum &lt;strong&gt;safe&lt;/strong&gt; bank angle of a 747?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That might depend on who is making the safety assessment and what the alternatives are. There might be circumstances where a pilot might feel that being the first pilot to bank a 747 at 70° would be &lt;strong&gt;safer&lt;/strong&gt; than colliding with a mountain or another aircraft, or being shot down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA collect &lt;a href=&quot;http://www.tc.faa.gov/its/worldpac/techrpt/ar04-44.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;&quot;Statistical Data for the Boeing-747-400 Aircraft in Commercial Operations&quot;&lt;/em&gt;&lt;/a&gt;. For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.tc.faa.gov/its/worldpac/techrpt/ar04-44.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Lxty.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the FAA discard from the data any bank angles greater than 40.  My guess would be that airlines and/or pilots consider angles greater than those shown in this graph to be unsafe (at that stage of flight?) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This data seems to be related to touchdowns. Perhaps greater angles are safely used at high altitude.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;JA8119, a 747 SR-100, after an explosive decompression and loss of vertical-stabilizer seems later to have briefly survived an 80° roll without the aircraft breaking up. In the &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/632.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;accident report&lt;/a&gt; is this record from the flight data recorder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qFXxb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This aircraft was essentially uncontrollable, experiencing phugoid cycles and dutch rolls and tragically crashed shortly thereafter. However maybe it suggests an undamaged 747 might be able to survive quite high bank angles (assuming RLL in the report means roll-angle). As Peter Kämpf noted in a comment, it may not be safe to draw conclusions about the flight characteristics of undamaged 747s from this data.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-10T20:44:15.953" LastActivityDate="2014-08-10T20:44:15.953" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8077" PostTypeId="1" CreationDate="2014-08-10T21:16:22.990" Score="10" ViewCount="1646" Body="&lt;p&gt;In response to Peter Kämpf's answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on&quot;&gt;this question&lt;/a&gt;, why did moving the CG back on the Wright Flyer improve its stability?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-02-13T21:51:10.287" Title="Why did moving the CG aft on the Wright Brother's plane improve handling?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8078" PostTypeId="2" ParentId="8077" CreationDate="2014-08-10T23:35:32.990" Score="2" Body="&lt;p&gt;For a plane to be stable, small control input should lead to small corrections. Also, small air currents should lead to small deviations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider what happens when the Flyer pitches a bit down. It picks up speed, and the wing generates more lift. If the CG is to far forwards, the wing lift generates torque which pitches the nose even further down. In other words, that small change is amplified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving the CG aft reduces the torque change on pitch changes, which means that small changes remain small - and thus the plane is stable.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2014-08-10T23:35:32.990" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8079" PostTypeId="2" ParentId="8077" CreationDate="2014-08-10T23:39:39.580" Score="19" Body="&lt;p&gt;It did not improve stability, but flyability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wright Flyer had the CG located aft of the neutral point and was unstable in pitch. A longitudinally unstable aircraft will deviate from its trim point, and when flown by a human pilot, will have a wavy flight path. The Wrights called this undulation. It is caused by the delay in the pilot's response and his tendency to overcompensate, so the aircraft is oscillating around the trim point (= the angle of attack where all moments around the pitch axis are in balance). This delay is more problematic when the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eigenfrequency#Vibration_analysis&quot; rel=&quot;noreferrer&quot;&gt;eigenfrequency&lt;/a&gt; of the motion is higher. All Zeppelins were unstable in pitch above a certain airspeed and in yaw over the full speed range, but nobody bothered. These things were so big that any motion needed a long time to develop and deviations from the trim condition were easy to correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With aircraft, things are different, because they are more maneuverable and much smaller. The characteristic parameter here is the short period mode which characterizes the pitch motion. Its frequency is around 1 Hz for small aircraft and can be approximated like this:&#xA;$$\omega_{\alpha} = \frac{v_{\mathrm{trim}}}{i_y} \cdot \sqrt{\left(\frac{c_{m\alpha}}{\mu} + \frac{c_{L\alpha}\cdot c_{mq}}{\mu^2}\right)}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $\omega_{\alpha} \:\:\:$ Eigenfrequency of the short period mode&lt;br&gt;&#xA;    $v_{\mathrm{trim}}\:$  trimmed airspeed&lt;br&gt;&#xA;    $i_y \:\:\:\:\:$  Radius of inertia around the pitch axis&lt;br&gt;&#xA;    $c_{m\alpha} \:\:$ pitch moment gradient over angle of attack&lt;br&gt;&#xA;    $\mu \:\:\:\:\:\:$  reduced mass. $\mu = \frac{2\cdot m}{\rho \cdot S \cdot l_{\mu}}$&lt;br&gt;&#xA;    $c_{L\alpha} \:\:$ lift coefficient gradient over angle of attack&lt;br&gt;&#xA;    $c_{mq} \:\:$ pitch damping coefficient&lt;br&gt;&#xA;    $m \:\:\:\:\:$  mass&lt;br&gt;&#xA;    $\rho \:\:\:\:\:\:$  density of air&lt;br&gt;&#xA;    $S \:\:\:\:\:\:$  reference area (normally wing area)&lt;br&gt;&#xA;    $l_{\mu} \:\:\:\:\:$  mean aerodynamic chord&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question, all it needs is the first factor of the equation. The frequency increases with airspeed and goes down with the pitch inertia of the plane. By adding a weight at the back of their airplane, the Wrights increased this pitch inertia, thus lowering the eigenfrequency and making it easier to control. Make no mistake: The Flyer became even more unstable, but the instability became easier to correct because the deviations from the trim point built up more slowly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern replicas of the Flyer have their CG ahead of the neutral point and are naturally stable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-13T21:51:10.287" LastActivityDate="2015-02-13T21:51:10.287" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8080" PostTypeId="2" ParentId="8073" CreationDate="2014-08-11T01:27:32.363" Score="16" Body="&lt;p&gt;Some information in additional to the excellent answers already given:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, let's say the need for the emergency turn occurred just after leveling from a typical step climb of 2,000 ft, which would probably mean you had only about 1.3g buffet limit protection, although in good conditions we often went up when we had only 1.2g. Given Murphy's law, let's say we're at 1.2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the need for the turn comes. For the first several seconds, we dare not exceed 1.2g lest we enter a region of possible uncontrollability. We need to lose at least a couple of thousand feet as quickly as possible to get down to where we can start asking more of the wing. At the same time we want to use what the wing can safely provide to turn us. The steeper the turn the more that will be and the faster we will fall. Both good for a very short while. My seat of the pants guess is that we would roll to whatever extreme we were comfortable with, and then almost immediately start lessening the bank at a rate and to a degree dictated by what our speed was and how fast it was increasing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The overspeed clacker should go off around mach 0.92, although in maintenance test flights I've seen it not start until almost 0.94. At whatever point it goes off, we'd want to start reducing the bank, and we'd want to replace the lost turning force and addressing overspeed by increasing the angle of attack to what the wing could safely do buffet-wise. By the time we'd dropped, say, 4000 ft, buffet speed would no longer be a factor, and we could safely pull something like 1.8g (or higher if necessary).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be a matter of playing our bank and angle of attack to get what we want. &#xA;In thinking through this scenario, I'm informed (or at least I think I am) by two things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First is the incident on Dec 12, 1991 described in &lt;a href=&quot;http://www.ntsb.gov/safety/safety-recs/recletters/A92_31_35.pdf&quot; rel=&quot;noreferrer&quot;&gt;this NTSB report (PDF)&lt;/a&gt; and &lt;a href=&quot;http://community.seattletimes.nwsource.com/archive/?date=19911219&amp;amp;slug=1323954&quot; rel=&quot;noreferrer&quot;&gt;in this article&lt;/a&gt;. I was a captain at Evergreen at the time (in fact had flown that very airplane a few weeks earlier and had noticed the autopilot anomaly which was to later cause the incident), and I knew and talked to the aircrew (as did everyone at the company).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pertinent to this discussion is the fact that the aircrew did not notice what was happening until the INS gyros tumbled (old Carousel system with actual gyros), which happened as the airplane reached 90 degrees bank as I remember. Max bank angle prior to the start of recovery was 95 degrees. Also, the engines were at cruise power until the start of recovery. There's controversy as to the max speed reached; estimates ranged from mach 0.98 to 1.09 (a mach 1.25 report was spurious). Max nose down was 35 degrees. Altitude loss was approximately 10,000 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having read the previous answers, I'm a little less comfortable with the 80 degrees scenario, but I don't think that it would mean disaster. INS platforms would still be up. Speed I feel would be manageable given that we're going to idle thrust right at the beginning, and the speed brakes would help on that. The difference, though, between using 70 degrees and 80 degrees would probably be pretty small. The pdf referenced in the first link talks about another 747 going to 71 degrees as I remember.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, we had a simulator exercise in which we would sometimes exceed 60 degrees of bank, although I can't say for sure that I ever went to 80 degrees. The scenario would start with departure control saying, &quot;You have a bomb aboard timed to go off in 5 minutes. Cleared to land any runway.&quot; The sim instructor, of course, would have put you in what he felt was as difficult but still doable situation as possible. So, what you did was power off, start throwing out all the drag you could (screw the speed limitations), and roll to whatever degree of bank would start you getting lined up. The exercise always started from a relatively low altitude, so buffet speed was not an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Makes me teary-eyed thinking of fun times past.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="65" LastEditDate="2015-03-12T14:25:50.943" LastActivityDate="2015-03-12T14:25:50.943" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8081" PostTypeId="1" AcceptedAnswerId="8083" CreationDate="2014-08-11T06:15:25.510" Score="35" ViewCount="33811" Body="&lt;p&gt;I have limited experience with flight simulators but I have never bumped into a plane with manual transmission while, on the contrary, it's very common for other means of transportation (like cars and bikes) that rely on engine with some form of transmission control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, I'd like to know if it's actually true that no airplane have (or had) manual transmission and, secondly, why that is so. &lt;/p&gt;&#xA;" OwnerUserId="3150" LastEditorUserId="64" LastEditDate="2015-01-13T16:32:06.307" LastActivityDate="2019-10-25T19:31:40.280" Title="Why do airplanes not have manual transmission?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="9" CommentCount="8" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8082" PostTypeId="2" ParentId="8081" CreationDate="2014-08-11T06:29:04.800" Score="46" Body="&lt;p&gt;Because most aircraft engines do not have geared transmission at all:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GlMZH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:CF6-6_engine_cutaway.jpg&quot; rel=&quot;noreferrer&quot;&gt;wiki&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power is directly transmitted from the turbine to the compressor with a rigid shaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is true, though, that some engines have it, in particular, propeller engines:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zensp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;http://www.atsb.gov.au/publications/investigation_reports/2004/aair/aair200401353.aspx#tab_2_content&quot; rel=&quot;noreferrer&quot;&gt;ATSB&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but you have to realize that this a fixed gear ratio, no gear shifting is involved and thus, no manual nor automatic &quot;transmission&quot; is required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you might have, in &quot;old style&quot; propeller engines, is different levers/knobs for manifold pressure/throttle, propeller pitch and mixture.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-08-11T06:29:04.800" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8083" PostTypeId="2" ParentId="8081" CreationDate="2014-08-11T06:42:30.690" Score="55" Body="&lt;p&gt;Aircraft have &lt;strong&gt;fixed&lt;/strong&gt; gears (when they have gears at all)! However in a sense a variable-pitch propeller can be considered analogous to transmission in a car and it was manual in some aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power transmitted by propeller is, within some reasonable range, proportional to its rotation rate. And so is, again within some reasonable range, the power produced by the engine. So for slow planes a fixed pitch propeller with connected by fixed gear does a decent job. As you open the throttle, the engine speed increases, so does the propeller and that's exactly what it needs to do to transmit the power. Simpler aircraft have no gears at all and propeller is mounted directly on the engine shaft, higher power engines often have 2:1 reduction gear as the engine rpm would be too high for a propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now at higher speed, the apparent propeller pitch is reduced as the air is already moving, so it would spin faster and faster and eventually too fast for the engine. To counter this, faster propeller-driven aircraft have variable pitch propeller. As speed increases, it is set to higher angle of attack (coarser) so it keeps delivering power without increasing rpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early variable pitch propellers had manually controlled pitch, but quite quickly constant speed propellers were developed (many WWII aircraft had them already) where a weight-on-spring controls the propeller pitch so that constant rpm is maintained. The manually controlled units required a lot of attention and the constant-speed system is rather simple, so manual pitch control was quickly abandoned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that is kind of equivalent to perfect variable gear transmission. The pilot still has a throttle lever and a propeller pitch lever and selects power and rpm independently. Higher rpm allow higher power, but don't require it, so landing is usually done with low power, but max rpm so the engine reacts quickly if power is added (does not need to spin up). During cruise some more moderate value is selected (according to manufacturer recommendation) to reduce wear of the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turboprop engines always have constant-speed propellers, because in a turbine engine the difference between turbine speed at idle and at full power is not actually that big. Again the rpm limits maximum power, so landing is done with low power, but high rpm and the engine reacts quickly when power is added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last the turbojet/turbofan engines just turn the turbines and compressors as they need. It's not much different from the fixed propeller really, though the jet engines now usually have variable guide vanes in the stator (that are just linked to rpm).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-08-11T10:05:52.723" LastActivityDate="2014-08-11T10:05:52.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8084" PostTypeId="1" AcceptedAnswerId="8086" CreationDate="2014-08-11T08:03:04.283" Score="46" ViewCount="13201" Body="&lt;p&gt;Can commercial airliners theoretically taxi backwards using reverse thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this is possible, why isn't it common? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can already imagine some safety reasons...&lt;/p&gt;&#xA;" OwnerUserId="744" LastEditorUserId="1696" LastEditDate="2015-03-20T15:23:57.700" LastActivityDate="2018-07-12T19:28:18.227" Title="Is it possible to use thrust reversers to taxi backwards?" Tags="&lt;taxiing&gt;&lt;thrust-reverser&gt;&lt;powerback&gt;&lt;pushback&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8085" PostTypeId="2" ParentId="8084" CreationDate="2014-08-11T08:22:52.390" Score="17" Body="&lt;p&gt;It can be done, in fact the DC-9 and MD-80 aircraft are approved for backing up using reverse thrust. It is called &quot;powerback&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is rarely used since it is quite fuel consuming, noisy and increases the risk of sucking up debris near the gate area causing damage to the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=-Zkxh903s_w&quot;&gt;Here's a video&lt;/a&gt; of an MD-80 backing up. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-08-11T08:22:52.390" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8086" PostTypeId="2" ParentId="8084" CreationDate="2014-08-11T08:26:54.293" Score="55" Body="&lt;p&gt;This is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Powerback&quot; rel=&quot;noreferrer&quot;&gt;Powerback&lt;/a&gt;, most aircraft can do it, but it is not done very often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a jet aircraft, the three main problems are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reverse thrust tends to throw a lot of debris into the air because the exhaust is deflected to the sides and up and down too. This debris can damage the engine itself, other things on and around the aircraft or injure someone on the ramp. It is less of a problem for aircraft with tail-mounted engines (so DC-9s often used powerback), but that engine configuration is not used as much any more in transport aircraft, as it is less aerodynamically efficient.  &lt;/li&gt;&#xA;&lt;li&gt;A related problem is that the compressor might suck in its own hot exhaust gases. This might lead to temperature-induced damages in the last (high-pressure) stages of the compressor and health issues for passengers, since the air conditioning system works with bleed air from the compressor.&lt;/li&gt;&#xA;&lt;li&gt;Reverse thrust is rather inefficient on jet engines, so it uses a lot of fuel.&lt;/li&gt;&#xA;&lt;li&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/8084/taxiing-backwards-with-reverse-thrust/8086#comment14108_8086&quot;&gt;Casey mentioned in the comment below&lt;/a&gt;, the pilot has to be careful using the brakes during powerback: the main wheels are very close behind the centre of gravity, so harder braking can lift the nose wheel, causing the pilot to lose control and even causing damage to the tail if it hits the ground (“tail-tipping”).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So a tug is both cheaper and safer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In propeller aircraft, reverse is more efficient and does not throw up as much debris, so it is sometimes used. But a tug is still preferred because transport aircraft don't have any rear visibility, so the pilots can't see where they are taxiing. With tug the driver can see behind the aircraft, and a ground marshaller walks along side each wingtip with an intercom  connected to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, since aircraft are able to turn almost on the spot using differential braking and thrust and 180-degree nosewheel steering, at airports with few facilities there is generally enough space around the aircraft to permit the pilot to reverse out easily.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-12-08T20:44:29.197" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8087" PostTypeId="2" ParentId="8081" CreationDate="2014-08-11T09:33:06.917" Score="23" Body="&lt;h2&gt;Torque&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I suspect that the real answer involves torque. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Engine RPM with vehicle stationary&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Aircraft engines don't have or need multiple gears because the engine doesn't move the aircraft from standstill by applying torque to wheels. Instead an aircraft engine can run at full RPM while the aircraft is stationary at the start of a runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you put your car in top gear (6th?), ran it at maximum RPM (8000?) and dropped the clutch, something would break - at the very least you'd burn the clutch and crawl away slowly. Aircraft engines don't have or need a clutch, ultimately because they are pushing air, not turning wheels on tarmac.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-08-11T09:33:06.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8088" PostTypeId="1" AcceptedAnswerId="8278" CreationDate="2014-08-11T10:45:52.357" Score="9" ViewCount="1480" Body="&lt;p&gt;What is the ratio of flights that follow the track system in the north Atlantic and those that don't? Also what is the general trend in this ratio over time?&lt;/p&gt;&#xA;" OwnerUserId="3053" LastEditorUserId="167" LastEditDate="2015-09-08T00:54:54.210" LastActivityDate="2017-02-16T14:39:58.993" Title="How many flights follow the North Atlantic Track relative to those that don't?" Tags="&lt;navigation&gt;&lt;oceanic&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8089" PostTypeId="1" AcceptedAnswerId="8091" CreationDate="2014-08-11T11:26:25.910" Score="12" ViewCount="4164" Body="&lt;p&gt;On WikiPedia, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Progress_D-27&quot; rel=&quot;noreferrer&quot;&gt;Progress D-27&lt;/a&gt; is described as a propfan engine and the airplane it powers, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-70&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-70&lt;/a&gt;, is described as propfan-powered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.airspacemag.com/history-of-flight/the-short-happy-life-of-the-prop-fan-7856180/?no-ist=&amp;amp;page=5&quot; rel=&quot;noreferrer&quot;&gt;Air&amp;amp;Space magazine article&lt;/a&gt; contradicts that; it states that the An-70 is turboprop (not propfan) powered, as is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A400M&quot; rel=&quot;noreferrer&quot;&gt;Airbus A400M&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And indeed the basic configuration of the D-27 and the A400M's &#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Europrop_TP400&quot; rel=&quot;noreferrer&quot;&gt;EuroProp TP400&lt;/a&gt; turboprop are very similar:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;4.5 m propeller diameter vs 5.2 m&lt;/li&gt;&#xA;&lt;li&gt;14,000 hp vs 11,000 hp&lt;/li&gt;&#xA;&lt;li&gt;two-shaft gas generator, third shaft to drive propeller&lt;/li&gt;&#xA;&lt;li&gt;propeller driven through reduction gearbox&lt;/li&gt;&#xA;&lt;li&gt;propeller blades mounted before engine&lt;/li&gt;&#xA;&lt;li&gt;780 km/h max speed vs 780 km/h cruise speed&lt;/li&gt;&#xA;&lt;li&gt;variabele pitch blades&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only significant difference is that the D-27 has two contra-rotating blade sets while the TP400 uses only one blade set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having contra-rotating propellers does not necessarily make a turboprop a propfan though (e.g. the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tu-95&quot; rel=&quot;noreferrer&quot;&gt;Tu-95&lt;/a&gt; is a turboprop aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So all things considered, what would make the  D-27 really a propfan but not the TP400?  Is there really a distinction between a propfan and a turboprop?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="64" LastEditDate="2015-01-09T23:52:44.313" LastActivityDate="2018-04-05T02:22:39.950" Title="Is the Progress D-27 really a propfan?" Tags="&lt;propeller&gt;&lt;turboprop&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8090" PostTypeId="2" ParentId="8089" CreationDate="2014-08-11T12:58:52.967" Score="5" Body="&lt;p&gt;Yes, it is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Propfan&quot; rel=&quot;nofollow&quot;&gt;Propfan Engine&lt;/a&gt;. This explains the increased number of blades in the propeller. Higher Disk Loading requires the use of smaller diameter propellers. The blades are scimitar-shaped, with swept-back leading edges at the blade tips to accommodate the large Mach numbers encountered by the propeller tip at high rotative and flight speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ivchenko-progress.com/?portfolio=d-27&amp;amp;lang=en&quot; rel=&quot;nofollow&quot;&gt;http://ivchenko-progress.com/?portfolio=d-27&amp;amp;lang=en&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact the manufacturers of AN-70, SE Ivchenko Progress, &lt;a href=&quot;http://ivchenko-progress.com/?p=2997&amp;amp;lang=en&quot; rel=&quot;nofollow&quot;&gt;themselves describes the D-27 as a Propfan&lt;/a&gt; (also &lt;a href=&quot;http://ilot.edu.pl/GeneralAviation/GA/CBravo06-Ivchenko-GA-TP-TF.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A propfan consists of swept, rotatable airfoil blades pivotally&#xA;  mounted to a hub for pitch change movement with respect thereto, and&#xA;  having a solidity ratio of 1.0 or greater at the roots of the blades&#xA;  and less than 1.0 at the tips of the blades. The prop fan is operable&#xA;  at or above critical Mach numbers and at transonic or supersonic tip&#xA;  speeds, and is characterized by: each of the blades having a leading&#xA;  edge. The leading edge, from a location thereon at approximately a&#xA;  midportion of the span and the blade, outwardly to the tip thereof, is&#xA;  curved in a chordal direction to define blade sweep while exhibiting&#xA;  no significant offset curvature in a span-wise direction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.google.com/patents/US4730985&quot; rel=&quot;nofollow&quot;&gt;http://www.google.com/patents/US4730985&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="1696" LastEditDate="2014-08-11T21:41:03.187" LastActivityDate="2014-08-11T21:41:03.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8091" PostTypeId="2" ParentId="8089" CreationDate="2014-08-11T20:31:07.120" Score="19" Body="&lt;h2&gt;It depends&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It seems that currently the term is more a marketing term than an engineering term.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When fears arose among airline officials that the word “turboprop” would meet with consumer resistance, the term “prop-fan” was used in a poll of United Airlines passengers. It worked: 50 percent of the respondents said they’d fly on a prop-fan-powered airliner. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From &lt;a href=&quot;http://www.airspacemag.com/history-of-flight/the-short-happy-life-of-the-prop-fan-7856180/?c=y&amp;amp;no-ist&quot;&gt;Air&amp;amp;Space Magazine&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It depends which particular features you consider an essential defining element for the term &quot;propfan&quot;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Turboprop?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Many features of propfans are also found on some powerplants described as turboprops by their makers.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Contra-rotating blades? - Found on, for example the 1950's &lt;a href=&quot;http://en.wikipedia.org/wiki/Kuznetsov_NK-12&quot;&gt;NK-12&lt;/a&gt; turboprop.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Supersonic tip speeds? - &lt;a href=&quot;http://en.wikipedia.org/wiki/Turboprop#History&quot;&gt;NK-12 turboprop&lt;/a&gt; again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;More than four blades? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 1945 &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_RB.50_Trent&quot;&gt;RB.50&lt;/a&gt; tuboprop had five. &lt;/li&gt;&#xA;&lt;li&gt;The 1984 &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PW100#mediaviewer/File:RAFO_EADS_CASA_C-295_901_PAS_2013_04_PW127G_turboprop_engine.jpg&quot;&gt;PW127&lt;/a&gt; turboprop drove a six-bladed prop. &lt;/li&gt;&#xA;&lt;li&gt;The 2009 &lt;a href=&quot;http://www.rolls-royce.com/defence/products/transporters/tp_400/&quot;&gt;TP400&lt;/a&gt; turboprop drives an eight-bladed propeller.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Curved blades? - TP400 turboprop.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Gearbox?&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No Reduction Gearbox - A key distinction of a key forerunner, the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE36&quot;&gt;GE36&lt;/a&gt;, was the lack of a reduction gearbox as used in turboprops. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Other names?&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GE called their GE36 an unducted fan (&lt;strong&gt;UDF&lt;/strong&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Rolls Royce call their design an &lt;a href=&quot;http://www.rolls-royce.com/about/technology/research_programmes/gas_turbine_programmes/sage.jsp&quot;&gt;&lt;strong&gt;open rotor&lt;/strong&gt; engine&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The acronym &lt;strong&gt;CROR&lt;/strong&gt; is also in used; it stands for Contra-Rotating Open Rotor.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;D27?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The marketing department of its designers &lt;a href=&quot;http://ivchenko-progress.com/?portfolio=d-27&amp;amp;lang=en&quot;&gt;call it&lt;/a&gt; a propfan.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Dictionaries&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Oxford&lt;/strong&gt; &lt;a href=&quot;http://www.oxforddictionaries.com/spellcheck/english/?q=propfan&quot;&gt;says&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Turbofan: A jet engine in which a turbine-driven fan provides additional thrust.&lt;/li&gt;&#xA;&lt;li&gt;Turboprop: A jet engine in which a turbine is used to drive a propeller.&lt;/li&gt;&#xA;&lt;li&gt;Propfan: No results found for “propfan”.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mirriam Webster&lt;/strong&gt; - same as Oxford essentially.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aviation terms.com&lt;/strong&gt; also defines turboprop etc but not propfan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/opssvs/secretariat-terminology-glossary-744.htm&quot;&gt;Aviation Canada&lt;/a&gt;&lt;/strong&gt;, and other aviation glossaries I looked at, also fail to mention propfan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dictionary.com&lt;/strong&gt; says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;propfan. Aeronautics. a turbojet having a turbine-driven propeller that operates completely outside the jet engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But that definition could equally apply to any turboprop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wordsense.eu&lt;/strong&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;propfan (pl. propfans) &#xA;  A modified turbofan engine with the propeller outside the engine duct of an aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which is not any better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wikipedia&lt;/strong&gt; tries to define propfan in terms of what it isn't. The nearest it gets to a definition is to say that a propfan has a propellor with &lt;em&gt;many short twisted blades&lt;/em&gt;. However the TP400 has many twisted blades - perhaps they are not short enough to qualify?&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Conclusion?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There doesn't currently seem to be a clear and short widely-agreed or widely-used set of engineering criteria for labeling a particular engine a &lt;strong&gt;propfan&lt;/strong&gt; rather than an &lt;strong&gt;advanced turboprop&lt;/strong&gt;, an &lt;strong&gt;unducted turbofan&lt;/strong&gt;, an &lt;strong&gt;open rotor&lt;/strong&gt; engine or any other name.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The D27 is a propfan because its maker's marketing department calls it that.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-13T16:17:55.727" LastActivityDate="2014-08-13T16:17:55.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8093" PostTypeId="2" ParentId="8047" CreationDate="2014-08-12T00:29:00.713" Score="4" Body="&lt;p&gt;Usually when the President visits LA or San Francisco there are one or more inner rings and at least one outer ring. The inner rings are usually 10 nm in diameter and &lt;em&gt;you&lt;/em&gt; can’t enter them under any conditions. The outer rings, on the other hand, are able to be flown into if you are on a VFR or IFR flight plan and in continuous contact with ATC. Here’s a portion of the TFR at Martha’s Vinyard.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FOR OPERATIONS WITHIN THE AIRSPACE BETWEEN THE 10 NMR AND 30 NMR&#xA;  AREA(S) LISTED ABOVE, KNOWN AS THE OUTER RING(S): ALL AIRCRAFT&#xA;  OPERATING WITHIN THE OUTER RING(S) LISTED ABOVE ARE LIMITED TO&#xA;  AIRCRAFT ARRIVING OR DEPARTING LOCAL AIRFIELDS, AND WORKLOAD&#xA;  PERMITTING, ATC MAY AUTHORIZE TRANSIT OPERATIONS. AIRCRAFT MAY NOT&#xA;  LOITER. ALL AIRCRAFT MUST BE ON AN ACTIVE IFR OR VFR FLIGHT PLAN WITH&#xA;  A DISCRETE CODE ASSIGNED BY AN AIR TRAFFIC CONTROL (ATC) FACILITY.&#xA;  AIRCRAFT MUST BE SQUAWKING THE DISCRETE CODE PRIOR TO DEPARTURE AND AT&#xA;  ALL TIMES WHILE IN THE TFR AND MUST REMAIN IN TWO-WAY RADIO&#xA;  COMMUNICATIONS WITH ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are departing or landing at an non-towered field, you need two radios (or an Garmin SL30 radio) to monitor ATC and communicate on the CTAF. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have done it lots of times VFR into LA and it really isn’t much different than getting flight following.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don’t have any experience with departing from a non-towered airport into the TFR, since the last time I entered the TFR the approach end of the runway at Catalina Island was in the 30 mile ring, but the departure end was not. So I don’t know for sure but from talking to the people at the FBO and reading the TFR, I think you need to open you flight plan either by phone or on the radio (Hawthorne radio would be who you call and the frequency depends on where you are in the LA basin), contact ATC (in this case LA Center, again frequency varies) on the ground before you take off, then make your normal calls on the CTAF. Then contact ATC again when you are airborne.&lt;/p&gt;&#xA;" OwnerUserId="1110" LastActivityDate="2014-08-12T00:29:00.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8095" PostTypeId="1" AcceptedAnswerId="8099" CreationDate="2014-08-12T03:23:34.320" Score="5" ViewCount="1859" Body="&lt;p&gt;I am currently working on my private pilot license and am using a headset from the flight school.  I am coming up to my first solo and thinking about purchasing my first headset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many different types of headset on the market, so what should I look for in a headset, and how do I go about picking the right headset for me?&lt;/p&gt;&#xA;" OwnerUserId="2368" LastEditorUserId="64" LastEditDate="2014-08-12T16:33:36.153" LastActivityDate="2014-08-12T18:34:04.977" Title="How to choose an aviation headset?" Tags="&lt;radio-communications&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8097" PostTypeId="2" ParentId="8081" CreationDate="2014-08-12T13:01:23.680" Score="4" Body="&lt;p&gt;A lot of complicated answers... but the simple truth lies in the term itself - transmission!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power must be transmitted, somehow, from the engine to whatever will push the vehicle forward - the wheels or the propeller. Internal combustion engines have an optimum power transmission rpm range - above or below which the efficiency of the engine drops drastically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between land vehicles and air or sea vehicles is, as mentioned by others here, that the friction between the wheel &amp;amp; land needs a much greater starting torque to get that wheel moving. Whereas, rotating a propeller through the air or water can be done much more easily &amp;amp; quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, this also ties up with why only land vehicles have (and can have) brakes. Neither air nor sea vehicles can have brakes. Because braking involves that same friction which was overcome to get the vehicle started. Due to lower co-efficients of friction, both sea &amp;amp; air vehicles continue to move even if the engine stops functioning. Obviously, air vehicles never need to be braked to a standstill while still in air. But water vehicles do and that is achieved by reversing the direction of the propellor's rotation.&lt;/p&gt;&#xA;" OwnerUserId="3168" LastActivityDate="2014-08-12T13:01:23.680" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8099" PostTypeId="2" ParentId="8095" CreationDate="2014-08-12T16:59:41.267" Score="7" Body="&lt;p&gt;First, do not buy any headset without trying it on.  Ignore those who say My Brand is the best!  Heads come in different shapes and to get a headset that is comfortable for you, you must try it/them on.  If possible, borrow a different one for each flight you take before you decide.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, if you are at all serious about this flying thing, pay up to get ANR headsets.  &quot;Active Noise Reduction&quot; (ANR) comes with different names (ENC is another that you will see) but they all reduce noise by creating &quot;anti-noise&quot; which has the same wave form (but inverted) as the noise you would otherwise hear, thus cancelling it out.  ANR headsets cancel the noise in the lower frequencies (engine rumble, exhaust noise, etc.) but permit higher frequencies to come through so that hearing radios, speech over the intercom, etc. is not affected.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, loud noise damages your hearing, and the effect of noise is &lt;strong&gt;&lt;em&gt;cumulative&lt;/em&gt;&lt;/strong&gt; over the years.  In most cases the hearing loss doesn't really manifest itself until later in life.  Act now to protect your hearing.  This is the reason that the diminishing number of WWII aviators are almost universally hard of hearing.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2014-08-12T18:34:04.977" LastActivityDate="2014-08-12T18:34:04.977" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8101" PostTypeId="1" CreationDate="2014-08-12T17:45:29.150" Score="11" ViewCount="6904" Body="&lt;p&gt;If I am just deplaning a commercial flight and I see the captain (4 bars on the epaulet) and want to thank him/her for a safe and enjoyable flight, I would say &quot;Excuse me, Captain, thanks for the nice flight&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if I were to encounter the first officer (3 bars), how should I address him or her? &quot;Excuse me, First Officer...?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably not &quot;Hey co-pilot!&quot; :)&lt;/p&gt;&#xA;" OwnerUserId="800" LastEditorUserId="65" LastEditDate="2015-03-10T13:39:47.717" LastActivityDate="2017-03-30T18:13:23.353" Title="How does one address a first officer in conversation?" Tags="&lt;pilots&gt;&lt;airlines&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8104" PostTypeId="2" ParentId="8095" CreationDate="2014-08-12T18:14:09.110" Score="9" Body="&lt;p&gt;The two main purposes of an aviation headset are &lt;a href=&quot;https://aviation.stackexchange.com/questions/2899/what-exactly-are-the-functions-of-an-aviation-headset&quot;&gt;making the cabin quieter, and making it easier to talk to ATC while keeping your hands free&lt;/a&gt;, so in selecting a headset you want to find one that will do both of those things very well.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To figure that out there are three major things you'll want to look at when picking a headset:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Noise Reduction Rating&lt;/strong&gt; (NRR)&lt;br&gt;&#xA;This value, expressed in decibels (dB), indicates how good the headset is at preventing cabin noise from reaching your ears.  A higher noise reduction rating cuts out more engine and wind noise (which prevents hearing damage and noise fatigue) and makes it easier to hear radio calls.&lt;br&gt;&#xA;Higher values are better - a headset with a 30dB NRR is quieter than one with a 24dB NRR.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Noise reduction ratings may be expressed as a positive or negative number (it's attenuation, so negative is &quot;more correct&quot;). &lt;code&gt;24dB&lt;/code&gt; or &lt;code&gt;-24dB&lt;/code&gt; means the same thing when reading specs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Headset Style&lt;/strong&gt;&lt;br&gt;&#xA;There are three basic styles of headsets, and one type will probably most comfortable for you.&lt;br&gt;&#xA;&lt;strong&gt;Earcup&lt;/strong&gt; headsets have earcups that surrond your ear, like classic David Clarks.&lt;br&gt;&#xA;&lt;strong&gt;In-Ear&lt;/strong&gt; headsets have earbuds/eartips that fit into your ear canal.&lt;br&gt;&#xA;&lt;strong&gt;Over-the-Ear&lt;/strong&gt; headsets are like headphones and sit &quot;over&quot; your ear (mainly for quiet cockpits).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2VHYu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2VHYus.jpg&quot; alt=&quot;David Clark Earcup Headset&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/Qn1zq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Qn1zqs.jpg&quot; alt=&quot;Clarity Aloft in-ear headset&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/w67Jl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w67Jls.jpg&quot; alt=&quot;Plantronics over-the-ear headset&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Weight&lt;/strong&gt;&lt;br&gt;&#xA;Self-Explanatory: You're going to have this &lt;em&gt;thing&lt;/em&gt; on your head for the duration of your flight. Wearing a 20-ounce (0.6 kg) headset is more fatiguing than a 10-ounce (0.3 kg) one, and you might have some neck pain if the headset is too heavy.&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Earcup headsets tend to be the heaviest - 12 to 24 ounces. Over-the-Ear headsets usually weigh in at 3-4 ounces, and in-ear headsets are generally 3 ounces or less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Secondary things to consider include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do you prefer Active or Passive noise reduction?&lt;br&gt;&#xA;Active Noise Reduction can make a very light headset &lt;em&gt;extremely&lt;/em&gt; quiet, but requires power (battery or ships power) and cost a bit more.&lt;/li&gt;&#xA;&lt;li&gt;What accessory functions would you like?&lt;br&gt;&#xA;There are headsets with Bluetooth, headsets with music inputs, etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ultimately the best way to pick a headset is to try several to see which you like best. You're evaluating them on some objective things (&quot;How quiet is it?&quot;) but also a lot of personal/subjective things: &quot;Is it too heavy?&quot;, &quot;Do the earcups/eartips fit my ear well?&quot;, &quot;Is the clamping force like having my head in a vise?&quot;, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your flight school may sell headsets, in which case ask to try a few different ones on your next few lessons to see which you like best. You can also chat with other pilots and try to get a ride with them to try out their headset (the exception to this often being in-ear headsets -- some folks get grossed out at the idea of having someone else's ear gunk on their tips).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-08-12T18:14:09.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8105" PostTypeId="1" AcceptedAnswerId="9897" CreationDate="2014-08-12T21:29:01.317" Score="7" ViewCount="1028" Body="&lt;p&gt;Regarding the &lt;a href=&quot;https://i.stack.imgur.com/68vSK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;recently announced TFR&lt;/a&gt; for the Ferguson, MO area, what is the process by which such a TFR is granted?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The official reason given is &quot;TO PROVIDE A SAFE ENVIRONMENT FOR LAW ENFORCEMENT ACTIVITIES&quot;, however, there has been significant commentary on social media arguing that this may be a politically-motivated act to prevent the media from scrutinizing the actions of law enforcement (for instance &lt;a href=&quot;https://twitter.com/Tom_Winter/status/499281721297498113&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, there is no (public) information regarding threats to airborne vehicles, and despite some initial reports most of the protests in the area have been peaceful.  I'd like to assume that this TFR was created for legitimate, non-political reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it common for the FAA to grant a TFR like this to local police?  What is the process by which this is done?  What criteria are considered by the FAA in determining whether such a TFR is warranted?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the sake of posterity, the full text of the TFR NOTAM is:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;!FDC 4/0271 ZKC MO..&#xA;AIRSPACE FERGUSON, MO..&#xA;TEMPORARY FLIGHT RESTRICTIONS. WITHIN AN AREA DEFINED AS 3 NM RADIUS OF &#xA;384428N0901812W (ST LOUIS VORTAC STL129011.0) SFC-3000FT TO PROVIDE A SAFE &#xA;ENVIRONMENT FOR LAW ENFORCEMENT ACTIVITIES. PURSUANT TO 14 CFR SECTION &#xA;91.137(A)(1) TEMPORARY FLIGHT RESTRICTIONS (TFR) ARE IN EFFECT. ONLY AIRCRAFT &#xA;PERMITTED UNDER THE PROVISIONS OF 14 CFR 91.137(B) ARE ALLOWED TO OPERATE IN &#xA;THIS 91.137(A)(1) TFR. THESE AIRCRAFT MUST BE OPERATING UNDER THE DIRECTION OF&#xA;THE UNIFIED COMMAND AT THE ST. LOUIS EMERGENCY OPERATIONS CENTER AND MUST &#xA;CONTACT THE MID-AMERICA AIR OPERATIONS BRANCH AT TELEPHONE 636-825-9341 OR &#xA;636-825-9342 FOR PERMISSION TO ENTER THE TFR PRIOR TO DEPARTURE. ST.LOUIS &#xA;GATEWAY TRACON, TELEPHONE 314-890-1017, IS THE FAA COORDINATION FACILITY. &#xA;MEDIA CONCERNS REGARDING THIS TFR SHOULD BE DIRECTED TO FAA PUBLIC AFFAIRS &#xA;THROUGH THE WASHINGTON OPERATIONS CENTER AT 202-267-3333. 1411250415-1411251015&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="3175" LastEditorUserId="64" LastEditDate="2014-11-25T05:53:53.790" LastActivityDate="2014-11-25T06:04:47.630" Title="What is the process for a TFR based on law enforcement activity?" Tags="&lt;faa-regulations&gt;&lt;tfr&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8106" PostTypeId="1" AcceptedAnswerId="8108" CreationDate="2014-08-12T22:11:02.910" Score="10" ViewCount="902" Body="&lt;p&gt;What is the perforated metal plating on the back of the A-6/EA-6 for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/M5RYj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Grumman_EA-6A_156983_VMCJ-2_America_30.09.74_edited-2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="14897" LastEditDate="2018-06-21T09:48:19.817" LastActivityDate="2018-06-21T09:48:19.817" Title="What is the metal plating on the back of the A-6 for?" Tags="&lt;aircraft-design&gt;&lt;feature-identification&gt;&lt;a-6&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8107" PostTypeId="2" ParentId="8081" CreationDate="2014-08-12T22:32:30.420" Score="4" Body="&lt;p&gt;Because propellers in water and air use the friction to move the object. And this friction is far less than the one between asphalt and tires. In one way, the gas is acting as gearbox. The other side of this coin is that it makes it hard to do fast accelerations from 0.&lt;/p&gt;&#xA;" OwnerUserId="3176" LastActivityDate="2014-08-12T22:32:30.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8108" PostTypeId="2" ParentId="8106" CreationDate="2014-08-12T22:36:34.133" Score="11" Body="&lt;p&gt;It is a speed brake, a plate hinged at the forward edge which can be hydraulically extended to increase aerodynamic drag. It had been used on early models, and the speed brakes were mostly replaced by firmly riveted plates later, because flight test revealed handling problems. The wake of the speed brake disturbed the flow around the horizontal tail especially during approach and landing. They were replaced by wing tip brakes, and from the 304th aircraft on were completely omitted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.joebaugher.com/usattack/newa6_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for further details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a picture of an A-6 with the wing tip speed brakes (circled red) extended:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NrByF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NrByF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;http://www.navy.mil/view_image.asp?id=15688&quot; rel=&quot;nofollow noreferrer&quot;&gt;navy.mil&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2018-06-21T09:41:59.427" LastActivityDate="2018-06-21T09:41:59.427" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="8109" PostTypeId="1" AcceptedAnswerId="8119" CreationDate="2014-08-12T23:03:59.963" Score="6" ViewCount="11470" Body="&lt;p&gt;I realized that some Boeing manuals recommend that the engine number 2 must be started first, is there any special reason for this?&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="572" LastEditDate="2014-08-13T09:00:47.590" LastActivityDate="2019-10-28T17:43:13.827" Title="Why is engine No.2 started first, instead of No.1?" Tags="&lt;jet-engine&gt;&lt;engine-starting&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8110" PostTypeId="2" ParentId="8105" CreationDate="2014-08-12T23:58:36.053" Score="2" Body="&lt;p&gt;It is quite common for TFRs to be issued over natural disasters, like hurricanes and tornadoes. In many cases they specifically state that they are issued to keep pilots who are not part of the relief operation from clogging the airspace. They are less frequent for incidents like this, but I have seen them before. There have been reports on Twitter and the media that shots have been fired at police helicopters, so that could be the motivation in this case to restrict the airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TFR itself says that the reason is “TO PROVIDE A SAFE ENVIRONMENT FOR LAW ENFORCEMENT ACTIVITIES” and I have no reason to doubt it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a bit puzzling about the TFR in this case is that it is in Class B airspace where controllers could presumably keep everyone away anyway. It also covers part of the St Louis airport. It would be interesting to know how that plays out. I guess this just makes it explicit that it could be dangerous.&lt;/p&gt;&#xA;" OwnerUserId="1110" LastActivityDate="2014-08-12T23:58:36.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8111" PostTypeId="2" ParentId="8101" CreationDate="2014-08-13T00:25:44.653" Score="17" Body="&lt;h2&gt;Call the FO '&lt;em&gt;Captain&lt;/em&gt;' anyway.&lt;/h2&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Both crewmembers are equally rated in the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The FO might have more time in the aircraft than the captain or even have been a captain at a previous airline, but is sitting in the right seat because of low seniority at this carrier.&lt;/li&gt;&#xA;&lt;li&gt;Nobody minds being referred to by a &lt;em&gt;higher&lt;/em&gt; title.&lt;/li&gt;&#xA;&lt;li&gt;You're a passenger, no one expects you to be able to read the bars on their uniform anyway.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-13T00:25:44.653" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8112" PostTypeId="1" CreationDate="2014-08-13T01:10:04.360" Score="4" ViewCount="4096" Body="&lt;p&gt;I'm looking at the Arriving flights page of the Vancouver Airport and in many cases there are several planes coming from the same airport, arriving at the same time, all at the same gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it count for only one plane and they are affiliated companies?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some screenshots:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Oho30.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sNeAK.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ovB6O.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3179" LastEditorUserId="700" LastEditDate="2014-08-15T09:49:53.737" LastActivityDate="2015-07-07T10:18:34.017" Title="Why do multiple planes arrive from the same airport at the same time?" Tags="&lt;airport&gt;&lt;codeshare&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8113" PostTypeId="2" ParentId="8081" CreationDate="2014-08-13T04:33:51.507" Score="7" Body="&lt;p&gt;Slightly different answer to the last one.  Air whipping engines don't need a lot of torque to push through viscous friction that resists blade travel.  That is why quadrotors work and yet are very light.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simple comparison, push against a wall and there is a normal force pushing back.  Now wave your arm in the air. The only resisting force is a function of your arm speed.  It's tiny.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they don't need to use gear reduction to increase torque like other applications, they don't need a gear changing transmission. In fact Bernoulli effect works on thrust from air flow over the blade so you want the propellers spinning as many times as possible to get maximum lift. Electric motors for quadrotors spin 10000 RPM for example.  They control motor spin speed through throttling air and fuel for turboprops or pulse width modulation for electric motors.  Turbines are air and fuel I think as well, but that's not my expertise.  &lt;/p&gt;&#xA;" OwnerUserId="3180" LastEditorUserId="3180" LastEditDate="2014-08-13T04:39:38.323" LastActivityDate="2014-08-13T04:39:38.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8114" PostTypeId="1" AcceptedAnswerId="8115" CreationDate="2014-08-13T05:15:04.477" Score="8" ViewCount="1319" Body="&lt;p&gt;I'm asking this question having watched a documentary about &lt;a href=&quot;http://en.wikipedia.org/wiki/Northwest_Airlines_Flight_85&quot;&gt;Northwest Flight 85&lt;/a&gt; in 2002, during which a &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400&quot;&gt;747-400&lt;/a&gt; experienced a lower rudder hardover at an angle of 17 degrees to the left. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots were able to recover by taking over manual control and using the ailerons, the upper rudder and asymmetrical engine thrust to oppose the forces being generated from the lower rudder hardover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the doco, I believe the pilot in control immediately turned off the autopilot as he realised it wasn't going to be able to recover from the initial roll. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just wondered if an autopilot would be able to recover from such an event - i.e. is it technically possible? It seems like the sort of thing an autopilot could achieve easier than a pilot, assuming it was programmed correctly.&lt;/p&gt;&#xA;" OwnerUserId="3181" LastActivityDate="2014-08-13T09:29:51.223" Title="Does the autopilot attempt to recover from a mechanical failure of a single control surface?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8115" PostTypeId="2" ParentId="8114" CreationDate="2014-08-13T05:39:05.603" Score="13" Body="&lt;p&gt;Normal autopilots don't. They expect all systems to work correctly, and in case of  failure of a single control surface they will stubbornly command actions which are no longer possible. For them, thrust is only for controlling the vertical speed, and the application of asymmetric thrust for yaw control is not possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are experimental autopilots which compare the result of their actions with a number of pre-programmed scenarios and select for their next commands the scenario which agrees best with reality. These really do what you assumed, but the specific scenario must have been considered before so the specific control laws are part of the code. Computers small enough to be carried on airplanes became powerful enough to do this in real time maybe 20 to 25 years ago, but I am not aware that regular autopilots of airliners have this capability even today. It is, however, used for unmanned vehicles.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-08-13T05:39:05.603" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8116" PostTypeId="2" ParentId="8112" CreationDate="2014-08-13T05:46:30.850" Score="13" Body="&lt;p&gt;This has to do with &lt;strong&gt;codesharing&lt;/strong&gt; or &lt;strong&gt;codeshare&lt;/strong&gt;. Two or more airlines can agree to share the same route and operate it with only one aircraft to reduce cost of operation.&lt;/p&gt;&#xA;&lt;p&gt;See the WikiPedia article on &lt;a href=&quot;http://en.wikipedia.org/wiki/Codeshare_agreement&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;codeshare&lt;/strong&gt; &lt;/a&gt;&#xA;Here an excerpt:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A codeshare agreement, sometimes simply codeshare, is an aviation business arrangement where two or more airlines share the same flight. A seat can be purchased on one airline but is actually operated by a cooperating airline under a different flight number or code&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the case where multiple flights are listed arriving at the same time from the same departure airports, there will only be one physical airplane serving the connection but under different flight numbers and operators. The different flight numbers and operators are listed to make it easier for passengers to identify their flight if codeshares are being used.&lt;/p&gt;&#xA;&lt;p&gt;On busy airports or where there is not enough space on the information displays to show all flights of a codeshare, the relation is only shown once with rotating flight numbers.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-07T10:18:34.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8117" PostTypeId="2" ParentId="8112" CreationDate="2014-08-13T07:00:02.237" Score="2" Body="&lt;p&gt;As SentryRaven correctly answered, they are codeshares.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is mainly that passengers want to buy tickets for the whole trip from a single company, because it is easier and because it makes it clear responsibility of that airline to rebook them on another flight if they miss a connection due to delay of previous flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to be able to offer better choice of connections, multiple airlines agree to sell tickets on the same flight and the flight then gets a separate number from each of them. It is especially common on short flights.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-08-13T07:00:02.237" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8118" PostTypeId="1" AcceptedAnswerId="8122" CreationDate="2014-08-13T07:38:00.047" Score="25" ViewCount="16077" Body="&lt;p&gt;In two-engine aircraft with wing-mounted engines when one engine quits the aircraft will have a natural tendency to turn &lt;em&gt;to&lt;/em&gt; the dead engine. So if you need to turn, it seems logical it should be easier to turn that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in &lt;a href=&quot;http://avherald.com/h?article=47897aae&quot;&gt;the discussion here&lt;/a&gt; is a comment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;sub&gt;By dinger on Monday, Aug 11th 2014 13:42Z:&lt;/sub&gt;&lt;br&gt;&#xA;  SOP in a twin is NOT to turn in the direction of the failed engine. Right engine failed and they turned Right.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is it really standard procedure, and if it is, what is the reason behind it?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="6" LastEditDate="2014-08-13T23:39:35.867" LastActivityDate="2019-06-23T21:08:01.787" Title="Why should you not turn in the direction of an inoperative engine?" Tags="&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="9" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8119" PostTypeId="2" ParentId="8109" CreationDate="2014-08-13T07:46:17.080" Score="13" Body="&lt;p&gt;The isolation valve in &lt;code&gt;Open&lt;/code&gt; or &lt;code&gt;Auto&lt;/code&gt; ensures that the Auxiliary Power Unit (APU) bleed air reaches the engine number 2 starter. Engine number 2 start Exhaust Gas Temperatures (EGT) are generally higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.lt-vacc.org/images/mesti/Boeing%20737-300-400-500%20Operations%20Manual.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.lt-vacc.org/images/mesti/Boeing%20737-300-400-500%20Operations%20Manual.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine number 2 is started first because it's on the opposite side of the air bridge. When starting with external air or power it is normal to start Engine number 1 because it is further away from the carts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://theflyingengineer.com/projects/airbus-tech/hydraulic-systems/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://theflyingengineer.com/projects/airbus-tech/hydraulic-systems/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Flight Crew Operations Manual (FCOM) 3 Standard Operating Procedures (SOP): &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Engine 2 is normally started first. It powers the yellow hydraulic system, which pressurizes the parking brake&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Looking at the electrical schematic that Boeing provides, we see that Transformer-Rectifier (TR) 3 is powered from the R/H AC Bus. TR 3 is an important TR from which significant avionics are powered. Ergo, you would want to have this TR powered up and running first in case you lose AC power to the aircraft during start.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="5517" LastEditDate="2019-10-24T17:37:30.037" LastActivityDate="2019-10-24T17:37:30.037" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="8121" PostTypeId="2" ParentId="8081" CreationDate="2014-08-13T07:58:54.620" Score="6" Body="&lt;p&gt;Flight simulators don't have geared transmissions because real planes don't have geared transmissions.&#xA;The closest thing a plane would have is a variable pitch prop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a vehicle with wheels, the engine rpm is easily calculated as a ratio with ground speed and the gearing.  There's nothing like that with an aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3183" LastActivityDate="2014-08-13T07:58:54.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8122" PostTypeId="2" ParentId="8118" CreationDate="2014-08-13T08:04:43.837" Score="44" Body="&lt;p&gt;The AvHerald comment is correct, you generally do not want to turn towards the dead engine. The aircraft will tend to turn (both yaw and bank) towards the dead engine due to asymmetric thrust, allowing it to do so at low speed will make it difficult to &lt;em&gt;end the turn&lt;/em&gt;, possibly to the point where you lose control. If you turn away from the dead engine, you'll have a tougher time getting &lt;em&gt;into&lt;/em&gt; the turn, but the live engine will help you get out of it. That said, attempting low altitude turns with an engine out seems like a bad idea, you should concentrate on going straight and maintaining optimum airspeed to make sure you get some altitude&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a couple of mnemonics when dealing with engine failures, like &quot;dead foot, dead engine&quot; (determining which engine failed) and &quot;raise the dead&quot; (keep bank towards the live engine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only speculate as to why they chose to go right, either they wanted to avoid the populated area, or they were already unable to control the turn. The high density altitude would certainly affect the OEI performance as well, perhaps luring them into losing airspeed below Vmc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I'm not multi engine rated, and have no first hand experience. This is just what I've read.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-08-13T08:25:43.403" LastActivityDate="2014-08-13T08:25:43.403" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8123" PostTypeId="5" CreationDate="2014-08-13T08:24:30.770" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-08-13T08:24:30.770" LastActivityDate="2014-08-13T08:24:30.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8124" PostTypeId="4" CreationDate="2014-08-13T08:24:30.770" Score="0" Body="Aviation business arrangement where two or more airlines share the same flight." OwnerUserId="247" LastEditorUserId="247" LastEditDate="2014-08-13T09:09:58.460" LastActivityDate="2014-08-13T09:09:58.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8125" PostTypeId="2" ParentId="8112" CreationDate="2014-08-13T08:38:06.740" Score="4" Body="&lt;p&gt;As others have already said, those are codeshare flights. Just to clarify, this means that there is only one physical plane flying this route at this particular time but it has several flight numbers for marketing reasons (it can also make a difference for things like frequent flyer miles, etc.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often, a three-digit flight number means the relevant airline is the “real” (or “operating”) carrier, whereas longer numbers are used by “virtual” (or “marketing”) carriers. Thus the first flight in your list would actually be operated by Lufthansa, the next one by Virgin Atlantic, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several entries on the arrival and departure list because different passengers will expect a different airline name and flight number (the codes like LH492 or AC9101) and need to be able to find it in the list. In some airports, there is only one line on the video displays in the terminal, with the flight number rotating every 30 seconds or so.&lt;/p&gt;&#xA;" OwnerUserId="3018" LastEditorUserId="3018" LastEditDate="2014-08-13T21:41:58.353" LastActivityDate="2014-08-13T21:41:58.353" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8126" PostTypeId="2" ParentId="8114" CreationDate="2014-08-13T09:29:51.223" Score="4" Body="&lt;p&gt;Not all autopilots have this capability, but it usually specifically added for airplanes that have split rudders and are highly susceptible to Dutch rolls without active yaw damping (T-tailed, large sweep, significant dihedral). This should be supplemented with adequate indication of the situation to the pilot, and newer glass cockpits are even introducing displays of corrective actions and restricted flight envelopes, where the pilot can have a reduced workload and airframe stress will be minimized. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, hardovers are probably the most difficult potential error to design against, and in some cases would be catastrophic if they occurred, regardless of any attempts at correction. If this is the case, it is part of the aircraft manufacturer's job to prove that the probability of such hardovers is statistically impossible (usually defined as less than one expected occurrence per billion hours of flight).&lt;/p&gt;&#xA;" OwnerUserId="3185" LastActivityDate="2014-08-13T09:29:51.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8127" PostTypeId="2" ParentId="7757" CreationDate="2014-08-13T10:49:52.460" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can a civilian aircraft pilot see a missile coming?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Around little more than 1% chance on takeoff/ascent phase up to flight height. (line of sight &amp;amp; missile trajectory won't intercept)&lt;/li&gt;&#xA;&lt;li&gt;Around a 1% chance during stable flight. (line of sight &amp;amp; missile trajectory won't intercept except changing corridor and corrections)&lt;/li&gt;&#xA;&lt;li&gt;There is a better % during descent/landing phase in case of head attack (line of sight &amp;amp; missile trajectory will intercept most likely but it's not a good position for evading. As a plane goes lower on landing - mobile complex could be used - no reason to spend expensive high range missile)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Chance to spot a missile is also better in air-craft with low windows in pilot cabin. Missiles are generally fired ahead to prevent flight from increasing range by flying away. So one may imagine a missile coming in usually at about a 45 degree angle ahead and from below and calculate chances for a pilot to spot it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If these missiles can be detected, can the pilot take any evasive measures?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on amount of passengers it's designed for and current load.&#xA;Less passengers means smaller weight, better maneuvering capabilities, more thrust per kilo of weight.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;50 or more passengers - no chance, except by a miracle. (such a craft is loaded with passengers, luggage, post, goods and is &quot;stuck&quot; in the sky to make a comfortable flight)&lt;/li&gt;&#xA;&lt;li&gt;about 25 passengers - some chances to try to do something, but unlikely to evade &lt;/li&gt;&#xA;&lt;li&gt;12 civilian passengers or less - one may bargain &lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Small civilian jet and a pilot with a military background - there is an exact % chance could be calculated depending on missile system.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;same goes for stunt pilots on appropriate plane. (missile systems just not designed to target these types of air-crafts too small, not much heat generated by the engine = more chances to lose aim)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Although, the first problem is in place. Pilot probably won't see a missile in time to react.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;p.s. Someone wrote about &quot;buk&quot;. These systems are distinguished easily by two or more paths left in the sky. Yes, two or more missiles per flight. So as we go back to the question, the second part: if you try to evade the first missile the second one specially designed for this case.  Typically two or four missiles are used in such old systems like &quot;buk&quot;. Amount of missiles per target and percentage of success shot is open information. &#xA;That is why I gave so low chances.&lt;/p&gt;&#xA;" OwnerUserId="3187" LastEditorUserId="2171" LastEditDate="2014-08-13T15:44:53.953" LastActivityDate="2014-08-13T15:44:53.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8128" PostTypeId="2" ParentId="6310" CreationDate="2014-08-13T11:43:38.143" Score="2" Body="&lt;p&gt;The B737 MEL say :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Use of reverse thrust is left to the discretion of each carrier. Techniques for controlling the aircraft with unsymmetrical reverse thrust should be developed and used in training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore the pilot must know if he is able to control the aircraft in this situation.&lt;/p&gt;&#xA;" OwnerUserId="3039" LastActivityDate="2014-08-13T11:43:38.143" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8129" PostTypeId="1" AcceptedAnswerId="8132" CreationDate="2014-08-13T21:27:47.880" Score="10" ViewCount="7258" Body="&lt;p&gt;I am interested if there is any law or regulation which prohibits carriers from seating children in a seat not adjacent to their parent/guardian?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am flying with a group of 17, which includes 2 infants (without allocated seats), but seven children ranging in age from 2-5. We opted not to pay the extra charge to pre-allocate seats, and the airline has allocated us seats spread around the aircraft in a configuration which does not allow an accompanying adult to sit next to a child.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was sure there was some air law which prohibited this on safety grounds, but have been unable to find it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question relates to the EU, but answers regarding other jurisdictions welcome.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="65" LastEditDate="2015-02-24T14:40:16.403" LastActivityDate="2016-02-23T19:34:13.950" Title="Can small children be seated away from their parents/guardians on a flight?" Tags="&lt;commercial-aviation&gt;&lt;easa-regulations&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="0" ClosedDate="2016-02-24T12:59:21.947" ContentLicense="CC BY-SA 3.0" />
  <row Id="8130" PostTypeId="1" CreationDate="2014-08-13T22:31:56.967" Score="8" ViewCount="2004" Body="&lt;p&gt;I was reading an article the other day that mentioned many smaller private jets are more efficient, faster, can climb quicker and land with less space than larger commercial aircraft. Some of the obvious metrics make sense such as shorter landing distances, but the efficiency peaked my curiosity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am basically asking what is the cost difference or &lt;a href=&quot;https://en.wikipedia.org/wiki/Available_seat_miles&quot; rel=&quot;nofollow&quot;&gt;cost per seat mile&lt;/a&gt; difference in say a a Boeing 737 vs a smaller often private jet, say an &lt;a href=&quot;http://www.embraerexecutivejets.com/en-us/jets/legacy-600/pages/overview.aspx&quot; rel=&quot;nofollow&quot;&gt;Embraer Legacy 600&lt;/a&gt; or similar with its maximum seat capacity setup.&lt;/p&gt;&#xA;" OwnerUserId="3193" LastEditorUserId="1696" LastEditDate="2015-12-09T18:53:53.690" LastActivityDate="2015-12-09T18:53:53.690" Title="How does cost per seat-mile differ between commercial and private jets?" Tags="&lt;commercial-aviation&gt;&lt;boeing&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8131" PostTypeId="2" ParentId="8129" CreationDate="2014-08-13T22:40:21.367" Score="3" Body="&lt;p&gt;I don't think there a &quot;law&quot;, but the flight staff would prefer that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When my children were young, they sometimes ended up separated from us. Usually they were just a row or two away from us. On several occasions the cabin personnel arrange with kind passengers to switch seats so my two children could at least be seated together.  &lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="65" LastEditDate="2015-02-24T14:41:43.757" LastActivityDate="2015-02-24T14:41:43.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8132" PostTypeId="2" ParentId="8129" CreationDate="2014-08-13T22:41:14.733" Score="12" Body="&lt;p&gt;This is what I could find. I looked on the Civil Aviation Authority's website and found this article.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=2207&amp;amp;pageid=12706&quot;&gt;Seating Allocation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Families, children and infants &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The seating of children close by their parents or guardians should be&#xA;  the aim of airline seat allocation procedures for family groups and&#xA;  large parties of children.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Young children and infants who are accompanied by adults, should&#xA;  ideally be seated in the same seat row as the adult. Children and&#xA;  accompanying adults should not be separated by more than one aisle.&#xA;  Where this is not possible, children should be separated by no more&#xA;  than one seat row from accompanying adults. This is because the speed&#xA;  of an emergency evacuation may be affected by adults trying to reach&#xA;  their children.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Whenever a number of infants and children are travelling together the&#xA;  airline should make every effort to ensure that they can be readily&#xA;  supervised by the responsible accompanying adults.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From what I read, it doesn't look like there is a law set in stone, but instead it is recommended by the CAA to be put in regular practice by airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was a law then Ryanair would have been in serious trouble for charging people extra  money to sit next to their kids.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.u.tv/News/Ryanair-booking-separates-mum-and-tot/de5eeea4-030f-49f7-b6f0-3dfaff31f08e&quot;&gt;Ryannair booking separates mum and tot&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3091" LastActivityDate="2014-08-13T22:41:14.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8133" PostTypeId="2" ParentId="2354" CreationDate="2014-08-14T12:18:32.490" Score="8" Body="&lt;p&gt;You are all right to a point / close:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the main factors in order of importance:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;White paint is both cheap and easy to apply.&lt;/li&gt;&#xA;&lt;li&gt;White paint on most of the aircraft allows for quick and easy    resale (the new airline simply puts new tail art on it).         &lt;/li&gt;&#xA;&lt;li&gt;White paint shows any anomalies quickly — hydraulic/fuel leaks,    dirt, damage.&lt;/li&gt;&#xA;&lt;li&gt;White paint has the best thermal reflective properties for both    radiation from the sun and reflected radiation from the&#xA;tarmac    (although in northern climates / winter this is reversed)!&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;People don't generally choose their airline because of it livery, they generally choose the cheapest fare. Therefore white paint is the colour of choice. It all boils down to money.&lt;/p&gt;&#xA;" OwnerUserId="3195" LastEditorUserId="4197" LastEditDate="2016-01-20T08:35:37.980" LastActivityDate="2016-01-20T08:35:37.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8135" PostTypeId="1" AcceptedAnswerId="8140" CreationDate="2014-08-14T15:59:17.023" Score="26" ViewCount="21492" Body="&lt;p&gt;I haven't looked at the Grand Canyon on a sectional yet, but I know that it is definitely big enough (by far) so that someone could fly a plane under the level of the rim and stil meet all of clearance requirements for VFR flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it legal, and safe to take an airplane into the canyon? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="14897" LastEditDate="2018-01-17T20:24:54.177" LastActivityDate="2021-04-01T03:27:08.307" Title="Can I fly &quot;into&quot; the Grand Canyon?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;visual-flight-rules&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8136" PostTypeId="1" CreationDate="2014-08-14T16:16:24.850" Score="29" ViewCount="8566" Body="&lt;p&gt;I have heard incidents in which commercial aircraft are required to dump fuel in event of an emergency to avoid landing over maximum landing weight. What systems do aircraft have in place to dump fuel? How is a fuel dump initiated from the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="97" LastEditDate="2014-10-29T01:11:02.730" LastActivityDate="2014-10-29T01:11:02.730" Title="How is fuel dumped in aircraft?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;aircraft-systems&gt;&lt;fuel-dumping&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8137" PostTypeId="2" ParentId="8136" CreationDate="2014-08-14T16:24:55.883" Score="31" Body="&lt;p&gt;Commercial aircraft have fuel dump nozzles located under the wings for dumping fuel. Fuel is gravity jettisoned from the tanks located in the wings and the fuselage. Large commercial aircraft such as the 747 can dump upto 6000 lbs of fuel per minute with all fuel jettison pumps open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oMF65.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the fuel dump nozzles are in different places on different aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the 747, the nozzles seem to be located near the wingtips:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5k313m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas on the A380, the nozzles seem to be much closer to the fuselage:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/enBp7m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is triggered by activating the FUEL JETTISON switches in the cockpit on the overhead panel. Below is a picture of the same in an Airbus A380-800. Both the ARM and ACTIVE switches must be pressed to start a fuel dump.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cnvcLm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="504" LastEditDate="2014-10-14T15:55:16.703" LastActivityDate="2014-10-14T15:55:16.703" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8138" PostTypeId="2" ParentId="8135" CreationDate="2014-08-14T16:25:48.273" Score="7" Body="&lt;p&gt;Safe maybe, but not legal. Not anymore - the helicopter tours did fly into the canyon years ago, but it became illegal in 1987, prompted by a mid-air collision in 1986. &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/arc/programs/grand_canyon_overflights/documentation/StatutoryRegulatoryandLitigationBackground.pdf&quot; rel=&quot;nofollow&quot;&gt;A Special Federal Aviation Regulations (SFAR)&lt;/a&gt; was adopted which regulates traffic below 14,500 ft MSL. This height limit can be raised seasonally to 18.000 ft, and only commercial tour operators are allowed to fly below. For GA traffic three small north-south lanes allow crossing at 10,500 (southbound) rsp. 11,500 ft (northbound). Now even the number of fixed wing and helicopter tour flights is restricted to reduce noise.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-15T07:58:52.410" LastActivityDate="2014-08-15T07:58:52.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8139" PostTypeId="2" ParentId="8135" CreationDate="2014-08-14T16:28:59.297" Score="11" Body="&lt;p&gt;It is generally not legal to fly &lt;em&gt;into&lt;/em&gt; the Grand Canyon - there is a SFRA (Special Flight Rules Area) over much of the canyon which is designed to keep General Aviation traffic from annoying tourists (and away from the commercial air tour operators). For both GA and commercial tours there are altitude restrictions which keep flights well above the canyon rim.&lt;br&gt;&#xA;(&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/&quot;&gt;You can download a chart of the Grand Canyon SFRA from the FAA&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were it legal it probably would not be the safest idea anyway: Inside the canyon there are strong, often unpredictable winds. The conditions would be similar to flying a mountain pass, but with substantially less clearance between your wings and the canyon wall in some places.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-14T16:28:59.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8140" PostTypeId="2" ParentId="8135" CreationDate="2014-08-14T16:43:00.537" Score="27" Body="&lt;p&gt;The answer is: no, normal flights are not allowed under the canyon rim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the sectional chart, you see this notice:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Srr0w.png&quot; alt=&quot;Sectional Chart Note&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Searching through the CFR (Title 14, Part 91) brings up this &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&amp;amp;rgn=div5#ap14.2.91.1&quot; rel=&quot;noreferrer&quot;&gt;Special Federal Aviation Regulation No. 50-2&lt;/a&gt; - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ther is also &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol2/xml/CFR-2012-title14-vol2-part93-subpartU.xml&quot; rel=&quot;noreferrer&quot;&gt;Supbart U&lt;/a&gt; of Part 93.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Subpart U regulations seem to be the most current applicable regulations (please correct me if I am wrong).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule applies to everything under 18,000 feet MSL within an area around the park (like the chart says).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except in an emergency or if otherwise necessary for safety of flight, or unless otherwise authorized by the Flight Standards District Office for a purpose listed in 93.309, no person may operate an aircraft in the Special Flight Rules Area within the following flight-free zones:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It then describes the four zones: Desert View, Bright Angel, Toroweap/Shinumo, Sanup Flight-free Zone. You can't fly through these, but between them are &quot;corridors&quot; in which you are allowed to fly above a certain altitude. See &lt;a href=&quot;http://www.nps.gov/grca/parkmgmt/upload/Map_Posters.pdf&quot; rel=&quot;noreferrer&quot;&gt;this map&lt;/a&gt; for locations of the Flight-Free Zones and corridors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also minimum sector altitudes for different areas, including the corridors, which are going to be the main thing preventing you from flying very low. The altitudes are different for commercial air tours versus transient and general aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;no person may operate an aircraft within 500 feet of any terrain or structure located between the north and south rims of the Grand Canyon.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are also noise limits depending on the aircraft type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some info on the background of these rules, see this &lt;a href=&quot;http://www.nps.gov/grca/parkmgmt/upload/GCNP_DEIS_Cover_through_Chapter_3.pdf&quot; rel=&quot;noreferrer&quot;&gt;NPS study&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-08-14T18:01:03.460" LastActivityDate="2014-08-14T18:01:03.460" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8141" PostTypeId="1" CreationDate="2014-08-14T18:08:35.577" Score="3" ViewCount="2817" Body="&lt;p&gt;What percentage of the world's airline operations are in the USA?  And how does this number compare to other first world countries such as the UK and Canada?  How about places like China and India?  And finally smaller third-world countries?&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2016-05-03T16:28:45.790" Title="What percent of the world's airline operations are in the USA?" Tags="&lt;airline-operations&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8142" PostTypeId="2" ParentId="8101" CreationDate="2014-08-14T18:12:25.893" Score="4" Body="&lt;p&gt;I address them both as sir/ ma'am.  That way it is just as respectable and won't make things awkward. &lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2014-08-14T18:12:25.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8144" PostTypeId="2" ParentId="8141" CreationDate="2014-08-14T19:16:05.270" Score="5" Body="&lt;p&gt;It may be a bit hard to find this data for many different countries, especially if you want to separate takeoffs and landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this &lt;a href=&quot;http://www.rita.dot.gov/bts/press_releases/bts038_14&quot; rel=&quot;nofollow&quot;&gt;data for the US&lt;/a&gt;, there were 757.1 thousand flights in May 2014, including both domestic and international. Of those, 683.0 thousand were domestic, and 74.1 thousand were international.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lots of information is available &lt;a href=&quot;http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/subject_areas/airline_information/index.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. &lt;a href=&quot;http://www.transtats.bts.gov/Data_Elements.aspx?Data=2&quot; rel=&quot;nofollow&quot;&gt;This&lt;/a&gt; indicates 8.3 million domestic and 1.4 million international flights in the US during 2013. This includes all carriers an all airports, including domestic all-cargo flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best data for Europe I could find is only in passenger count (the more common statistic). It looks like you have to request access to get more detailed information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this &lt;a href=&quot;https://www.eurocontrol.int/articles/forecasts&quot; rel=&quot;nofollow&quot;&gt;collection of data&lt;/a&gt; from Eurocontrol showed 9.548 million &quot;IFR Flight Movements&quot; in 2012. This would include all IFR flights, regardless of their type. A graph at the bottom shows figures for 2008. This shows a little over 8 million internal, and a little under 2 million arriving/departing. Since a domestic flight would be two movements (departure and arrival), this is 4 million and 2 million flights. As expected, Europe has a much higher percentage of international flights (about 1:2 international in Europe, versus about 1:9 in the US).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;a href=&quot;https://www.bitre.gov.au/publications/ongoing/files/domestic_airline_activity_2013a.pdf%20702321%20trips%20domestic/year&quot; rel=&quot;nofollow&quot;&gt;domestic&lt;/a&gt; and &lt;a href=&quot;https://www.bitre.gov.au/publications/ongoing/files/International_airline_activity_CY2013.pdf%20162207%20flights%20intl/year&quot; rel=&quot;nofollow&quot;&gt;international&lt;/a&gt; traffic in Australia, there are 702321 domestic flights and 162207 international flights in 2013, for a total of 864528 flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.parliament.uk/Templates/BriefingPapers/Pages/BPPdfDownload.aspx?bp-id=SN03760&quot; rel=&quot;nofollow&quot;&gt;Data from the UK&lt;/a&gt; show that there are about 800000 domestic and 1000000 international flights per year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could also order a year of &lt;a href=&quot;http://www.iata.org/publications/pages/wats.aspx&quot; rel=&quot;nofollow&quot;&gt;World Air Transport Statistics&lt;/a&gt; for only $799.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-24T16:18:09.987" LastActivityDate="2014-09-24T16:18:09.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8145" PostTypeId="1" CreationDate="2014-08-14T19:39:33.503" Score="5" ViewCount="11390" Body="&lt;p&gt;I heard that commercial flight logs are publicly available from the FAA, including mechanical delay reasons, etc.  Is this true?  If so, where can this information be found?&lt;/p&gt;&#xA;" OwnerUserId="3199" LastActivityDate="2016-04-06T21:01:05.410" Title="Where can I find a flight log archive for commercial flights?" Tags="&lt;faa&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8146" PostTypeId="1" AcceptedAnswerId="8151" CreationDate="2014-08-14T20:03:52.700" Score="16" ViewCount="3937" Body="&lt;p&gt;If the headsets and microphones for general aviation have the same impedance for helicopters and airplanes, then why do they have different connectors on them?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it simply to make more money from selling adapters and more headsets?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="572" LastEditDate="2014-08-15T06:17:59.703" LastActivityDate="2015-01-25T03:18:32.747" Title="Why do helicopters and airplanes use different headset plugs?" Tags="&lt;general-aviation&gt;&lt;avionics&gt;&lt;helicopter&gt;&lt;fixed-wing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8147" PostTypeId="1" AcceptedAnswerId="8150" CreationDate="2014-08-14T20:37:34.780" Score="40" ViewCount="37662" Body="&lt;p&gt;The answers to this &lt;a href=&quot;https://aviation.stackexchange.com/q/8136/3170&quot;&gt;this question&lt;/a&gt; make it clear how modern airliners dump fuel in the case of an emergency. As far as I understand, fuel dumping might be done to lower an aircraft's weight to the maximum landing weight, particularly soon after takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I understand, jet fuel is typically not safe. When I, as a complete outsider, hear of fuel dumping, I imagine a whole bunch of dangerous corrosive fuel being dropped on whatever happens to be below, and it sounds like a frankly awful idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes fuel dumping safe, or if it is dangerous what makes it worth it?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2019-12-09T16:33:02.933" Title="How is fuel dumping safe?" Tags="&lt;safety&gt;&lt;fuel-dumping&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8148" PostTypeId="2" ParentId="8130" CreationDate="2014-08-14T20:57:14.297" Score="6" Body="&lt;p&gt;I did some basic math to figure it out in terms of current gas prices.  I got that a private jet is about 6x more expensive.  Keep in mind it is probably more in reality because these jets aren't being used as much as an airliner so the rental price will be higher as well as the fuel.  But like I said, this was just an estimate based on current fuel prices and performance of an airliner vs a private jet, to give you an idea of the cost difference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zFtbT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2014-08-14T20:57:14.297" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8149" PostTypeId="2" ParentId="8147" CreationDate="2014-08-14T22:00:43.780" Score="21" Body="&lt;p&gt;It's not really safe in an environmental sense, but it's not that bad.  Jet fuel is essentially kerosene, which is harmful, but as far as engine/industrial fluids go, it's pretty benign.  Additionally, when an airplane dumps it, it's diluted so much by the time it makes it anywhere that it's not a significant concern anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip side, if an airplane didn't dump fuel and landed overweight, the potential side effects could be disastrous and could result in many injuries and damages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, it's choosing between two bad options, landing overweight or dumping fuel, and dumping fuel is the least bad of the two of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, it's quite a rare occurrence.  You are exposed to far more toxins just walking down the street of a city than from airplanes dumping fuel.&lt;/p&gt;&#xA;" OwnerUserId="66" LastActivityDate="2014-08-14T22:00:43.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8150" PostTypeId="2" ParentId="8147" CreationDate="2014-08-14T22:03:11.077" Score="48" Body="&lt;p&gt;Fuel dumping is almost always an emergency maneuver, and it is never good for the environment.  So the alleged danger from the dumping must be balanced with the imminent danger to the 200&amp;ndash;400 passengers involved.  It is never an easy decision but that's why the Captain gets paid the big bucks...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dumping fuel sounds dangerous but it is not.  It is not going to explode.  Jet-A can be compared to kerosene and I don't have that statistic so let's compare it to Diesel Fuel which is not dissimilar to Jet-A.  Diesel Fuel at 400&amp;deg;F(204&amp;deg;C) is as volatile as gasoline is at 70&amp;deg;F(21&amp;deg;C).  Obviously that is a big difference.  Jet-A also evaporates into the air, so little if any hits the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest danger I see is to the atmosphere.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="-1" LastEditDate="2014-08-17T19:44:50.163" LastActivityDate="2014-08-17T19:44:50.163" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8151" PostTypeId="2" ParentId="8146" CreationDate="2014-08-14T22:10:58.113" Score="24" Body="&lt;p&gt;It's a holdover from the old days when microphone technology wasn't as advanced.  The military adopted &quot;dynamic microphones&quot; as the standard, which were less noisy than the alternative &quot;carbon microphones.&quot;  Carbon microphones required a DC bias voltage to operate, and the dynamic ones did not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fast forward to current airplane microphones, which are electric, and still use a bias voltage, so if you plug a military dynamic microphone into a civilian airplane jack, the microphone would burn out from the voltage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what?  Well, helicopters were originally very military oriented, so they all were wired for dynamic microphones.  They used a different jack to avoid accidentally plugging the wrong type of microphone into the wrong type of jack.  Even though helicopters are widely used outside of the military now, the standard remains, and many emergency radio equipment (fire, medical, police, etc) still uses the dynamic standard.&lt;/p&gt;&#xA;" OwnerUserId="66" LastEditorUserId="1696" LastEditDate="2015-01-25T03:18:32.747" LastActivityDate="2015-01-25T03:18:32.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8153" PostTypeId="2" ParentId="8136" CreationDate="2014-08-14T23:03:23.940" Score="21" Body="&lt;p&gt;You may download the fuel system description for a B747-400 &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Fuel_%28B747-400%29.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. &#xA;(wait for the 20s countdown to complete).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a part of the &quot;747 Flight Crew Operations Manual&quot;. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(Note that all pictures are extracted from the Boeing Company documentation, available on several web sites. Some copyright applies, see Smart Cockpit which provide this copy. Also note that this documentation is definitely outdated, and is not intended to be used for actual operations)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here are the basic information for the fuel jettison operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The overhead panel&lt;/strong&gt; (which is above the head of the crew) has some controls:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PJlsm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1: Allows to select the quantity of fuel to remain in the tank (jettison is used primarily if the aircraft must be landed shortly after takeoff, not much fuel has been burnt, and the maximum weight allowed (or desired) for landing is not yet attained).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2,3: The button to activate jettison, left and right nozzles, and their lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4: The selector to arm the jettison system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the information screen (EICAS) will display the quantity to remain:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/US7A8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The can also sees the &lt;strong&gt;status of the fuel tanks&lt;/strong&gt; on the other EICAS screen:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZPRDm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1: This is a jettison nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2: The time required for the jettison operation (based on actual fuel flow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Jettison schematic&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(depends on the aircraft model, the documentation shows different models).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MMlNs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see pumps and valves (pairs of blank half discs)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fuel jettison mode of operation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The fuel jettison system allows jettison from all fuel tanks.&#xA;  Override/jettison pumps in main tanks 2 and 3 and the center wing tank&#xA;  pump fuel overboard through the jettison nozzle valves.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fuel jettison is initiated by rotating the fuel jettison selector to A&#xA;  or B. When a jettison control system is selected, the fuel temperature&#xA;  indication on EICAS is replaced with the fuel to remain quantity&#xA;  indication. The jettison manifold and jettison time display on the&#xA;  fuel synoptic. Rotating the Fuel To Remain selector decreases or&#xA;  increases the fuel to remain quantity.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pushing either fuel jettison nozzle valve switch ON activates all&#xA;  override/jettison and transfer/jettison pumps in the tanks containing&#xA;  fuel (pump switches must be ON) and opens the required jettison and&#xA;  transfer/jettison valves. The related jettison nozzle valve also&#xA;  opens. The jettison time is initially estimated using preprogrammed&#xA;  rates. The system begins updating the estimate based on actual fuel&#xA;  quantity rate of change ninety seconds after jettison begins.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Jettison terminates when total fuel quantity decreases to the fuel to&#xA;  remain quantity. The fuel to remain quantity indication changes color&#xA;  from magenta to white and flashes for five seconds. The jettison&#xA;  control system deactivates all operating override/jettison and&#xA;  transfer/jettison pumps. The related FUEL OVRD pump EICAS messages&#xA;  display until the Fuel Jettison selector is OFF.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now see &lt;a href=&quot;http://www.youtube.com/watch?v=AwhCKGjnf-w&quot; rel=&quot;noreferrer&quot;&gt;what it looks like from the cabin  &lt;img src=&quot;https://i.stack.imgur.com/6MPsq.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;, when all this expensive fuel is evaporated in flight (YouTube video).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=AwhCKGjnf-w&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VvZzm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2014-08-17T09:32:36.603" LastActivityDate="2014-08-17T09:32:36.603" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8154" PostTypeId="2" ParentId="8147" CreationDate="2014-08-14T23:29:40.877" Score="15" Body="&lt;p&gt;Up-voting @skipmiller, I offer this addendum&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;if it is dangerous what makes it worth it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;Emergency Landing After Takeoff&lt;/h2&gt;&#xA;&lt;p&gt;Large aircraft typically cannot land as heavily as they can take off. It's a structural issue. So fuel dumping would be done if an emergency did not allow the time to burn down to allowable landing weight.&lt;/p&gt;&#xA;&lt;h2&gt;Maintain Flight with Engine/Power Loss&lt;/h2&gt;&#xA;&lt;p&gt;If available power did not allow sustained flight one might dump fuel. Worse if you were over mountains and needed to stay high.&lt;/p&gt;&#xA;&lt;h2&gt;Ditching&lt;/h2&gt;&#xA;&lt;p&gt;There was a case of a C-130 - a high wing plane - ditching in the Atlantic. It floated for a couple days with empty gas tanks and had to be shelled to force it to sink.&lt;/p&gt;&#xA;&lt;h2&gt;Fuel Leak&lt;/h2&gt;&#xA;&lt;p&gt;If a wing tank fuel leak was causing aircraft balance problems one might dump from the opposite wing to keep the aircraft controllable.&lt;/p&gt;&#xA;&lt;h2&gt;Life Imitating Fiction&lt;/h2&gt;&#xA;&lt;p&gt;15 minutes after takeoff we lost all thrust on 3 engines. Our gross weight forced us into a controlled descent. Dumping most of our fuel might very well have kept us airborne on 1 engine, if not I think empty tanks would have limited possible fuel fire in the controlled crash. I was about to dump 45,000 lbs of JP-4 all over west Texas when we solved our engine problem.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-12-09T16:33:02.933" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="8155" PostTypeId="2" ParentId="8145" CreationDate="2014-08-15T00:50:54.157" Score="0" Body="&lt;p&gt;I believe &lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;Flight Aware&lt;/a&gt; allows you to view filed flight plans. It also lets you know where the aircraft is in-flight, although I am not sure how accurate that information is.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-08-15T00:50:54.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8156" PostTypeId="2" ParentId="8141" CreationDate="2014-08-15T04:28:28.943" Score="0" Body="&lt;p&gt;You can get a good feel for the numbers from &lt;a href=&quot;http://data.worldbank.org/indicator/IS.AIR.PSGR/countries?display=map&quot; rel=&quot;nofollow&quot;&gt;this world map&lt;/a&gt; which shows total passengers carried around the world. Note: click on the &quot;Points&quot; option at the top left of the map to show the figures labelled on the map. US dominates when it comes to air travel, when domestic and international are included, with 743 million passengers in 2013. China came second with 353 million, then UK with 118 million.&lt;/p&gt;&#xA;" OwnerUserId="3181" LastEditorUserId="3181" LastEditDate="2014-08-15T04:33:53.873" LastActivityDate="2014-08-15T04:33:53.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8157" PostTypeId="1" AcceptedAnswerId="8158" CreationDate="2014-08-15T08:11:28.943" Score="8" ViewCount="2817" Body="&lt;p&gt;I would like to go on a photo flight over Mt. St. Helens sometime while I'm in the Portland area.  I am aware of the weather conditions that are caused by mountains - but what precautions should I take to make sure that my flight over the &quot;summit&quot; is as safe as possible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it's worthwhile to mention that there is a wilderness area over Mt. St. Helens, so I will be above 2000ft AGL. &lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2014-08-15T11:15:58.087" Title="What precautions should I take when flying over a mountain?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8158" PostTypeId="2" ParentId="8157" CreationDate="2014-08-15T08:54:51.453" Score="18" Body="&lt;p&gt;When flying over mountains Pilots will have to encounter unpredictable winds, high density altitude, steeply rising terrain and box canyons, mountain waves, rotor clouds, turbulence, and clouds covering high ground . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.swaviator.com/html/issueAS99/basics.html&quot;&gt;http://www.swaviator.com/html/issueAS99/basics.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is therefore essential to take the below mentioned factors into consideration :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) &lt;strong&gt;ROUTE PLANNING&lt;/strong&gt; : When flying over mountains &lt;strong&gt;Route Planning&lt;/strong&gt; is extremely important because a straight line between two points may not always be the best way to go . Therefore, pick a route that avoids the rugged areas and highest peaks where an emergency landing could not be made. It usually takes very little extra time to bypass the most mountainous areas and follow major roads through more populated areas and lower terrain .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not approach a ridge until you have sufficient altitude to cross with a safety margin. If you encounter too much sink, you must have enough altitude to turn away towards lower terrain. To make that turn as easy as possible, its wise to turn your aircraft to a 45-degree angle to the ridge before you cross .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/airman/190015-1.html?redirected=1&quot;&gt;http://www.avweb.com/news/airman/190015-1.html?redirected=1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) &lt;strong&gt;THE TERRAIN FACTOR&lt;/strong&gt; : The rising terrain will often out climb non-turbocharged aircraft. If your aircraft has a service ceiling of 14,500 ft., that is based on standard atmospheric temperature which is 59 °F at sea level and decreases an average of 3.5 °F per thousand feet. If the surface temperature at 5000 ft. is 100 degrees, the density altitude on the ground is about 9,000 ft. When you climb to an indicated altitude of 9,500 feet you have reached the service ceiling of you aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) &lt;strong&gt;THE WIND FACTOR&lt;/strong&gt; : In a light aircraft, it is best to stay on the ground if the winds are greater than 35 miles per hour. Due to the venturi effect, winds will be much greater in the vicinity of mountain passes. Cross passes as high as possible, as downdrafts up to 2,000 feet per minute can occur on the leeward side.When strong winds of 40 to 50 miles per hour are blowing perpendicular to a mountain range, expect mountain waves and strong downdrafts for many miles on the leeward side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(4) &lt;strong&gt;THE CLOUD FACTOR&lt;/strong&gt; : The combination of rising ground and lowering ceiling can be deadly. Mountains disappear not only in clouds, but also at night. You should not fly over high territory after sunset unless you are at the minimum en route IFR altitude which provides a 2,000 ft. clearance along airways. When flying after dark, closely monitor your altitude and when in a turn, your rate of descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;&lt;em&gt;mountain checkout flight&lt;/em&gt;&lt;/strong&gt; is all that is required to get started. The checkout will enable you to operate around some pretty impressive terrain :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flatlander Focus&lt;/strong&gt; : Two good books on the market are The Mountain Flying Bible by Sparky Imeson, and Flying the Mountains: A Training Manual for Flying Single-Engine Aircraft by Fletcher Fairchild Anderson. Reading either one will give you a solid foundation on which to build your skills.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most Importantly - &lt;strong&gt;Know Your Aircraft &amp;amp; Its Limitations&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.caa.govt.nz/safety_info/GAPs/Mountain_Flying.pdf&quot;&gt;http://www.caa.govt.nz/safety_info/GAPs/Mountain_Flying.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) What distance over the ground does your &#xA;aircraft cover in a rate-one turn? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(b) What’s the distance for a steep turn? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(c) What speed and configuration do you use for reduced &#xA;visibility and for a minimum radius turn? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(d) What is the best-angle-of-climb speed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(e) Do you know the manoeuvring speed (VA) and &#xA;understand its application in potentially &#xA;turbulent conditions? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(f) How is your aircraft performance and handling affected by &#xA;altitude and turbulence? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(g) How is performance affected when operating at &#xA;maximum-all-up-weight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Needless to say recent practice and currency are vitally important.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="524" LastEditDate="2014-08-15T10:43:00.457" LastActivityDate="2014-08-15T10:43:00.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8159" PostTypeId="2" ParentId="8157" CreationDate="2014-08-15T11:15:58.087" Score="7" Body="&lt;p&gt;Mt. St. Helens has one hazard you are unlikely to encounter with any other mountain: it's an active volcano, with the most recent eruptive activity only six years ago.  This means that on the day of your flight, you should check both the relevant NOTAMs (for closures due to volcanic hazards) and the &lt;a href=&quot;http://volcanoes.usgs.gov/observatories/cvo/&quot;&gt;Cascade Volcano Observatory&lt;/a&gt; for unusual activity.  St. Helens will usually give weeks of warning before any eruptive activity, but you don't want to find yourself above the mountain with an ash cloud rushing towards you.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-08-15T11:15:58.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8160" PostTypeId="1" AcceptedAnswerId="8162" CreationDate="2014-08-15T13:48:39.787" Score="30" ViewCount="6511" Body="&lt;p&gt;When faced with the situation of a power off emergency landing, how do you best select your location to land?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what point is a road too small or the crosswind too great to attempt a safe landing and instead select a corn field or such? Should the road even be considered?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Also, how does plane size and build factor into the decision?&lt;/p&gt;&#xA;" OwnerUserId="2984" LastEditorUserId="19" LastEditDate="2017-04-07T13:25:57.097" LastActivityDate="2017-04-07T13:25:57.097" Title="What is preferred in an emergency landing: a road or a cornfield?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;unpowered&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8161" PostTypeId="2" ParentId="8160" CreationDate="2014-08-15T14:13:29.533" Score="17" Body="&lt;p&gt;If I had the option of a field, I'd take it. For small planes, roads are usually wide enough from shoulder to shoulder to not pose more of a problem in terms of cross wind landings than with a regular runway, but they are dangerous for a number of other reasons.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;People and vehicles. Your first priority should be to not take any innocent bystanders with you in your crash. With the engine out, they won't hear you coming either as in the unfortunate incident &lt;a href=&quot;http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20140727X14613&amp;amp;key=1&quot;&gt;in Venice, Florida the other day&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Poles, posts, and other obstacles along the side of the road. Power and telephone lines often run along roads if you're in a part of the world where they're still above ground. Road signs and other obstacles are bound to follow along the road ready to rupture your fuel tanks and throw a spark in the mix, bigger roads have bill-board sized signs going across the road as well. A good example caught on camera is the glider that attempted a road landing, &lt;a href=&quot;http://www.liveleak.com/view?i=673_1342792756&quot;&gt;only to have the wing catch a mail box&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Bigger roads often have a median barrier to separate traffic. It helped the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;Gimli glider&lt;/a&gt; slow down, you probably won't be so lucky.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I'd go for the road before the trees, but that's about it.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-08-15T14:24:29.633" LastActivityDate="2014-08-15T14:24:29.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8162" PostTypeId="2" ParentId="8160" CreationDate="2014-08-15T14:21:32.413" Score="29" Body="&lt;p&gt;Really depends on what you are flying, what's growing, what season and what the roads are like. Our Cessnas have used gravel roads a couple of times, either due to problems aloft or at the airport (bad weather). In the Alberta prairies finding a side road to land on is no problem whatsoever. 100 and 200-series Cessnas have fairly narrow fixed gear that can take an amazing amount of abuse, don't know about other types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A real cornfield, with the corn fully grown, will destroy a light aircraft. The plants are 2-3m high with a hard, heavy log of corn at the top. Hit a couple of thousand of them at 100km/h..... (Skydiving centers in corn country have firm advice for landing in the corn: keep your legs crossed.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ripe canola is also nearly 2m high and is a bushy plant interwoven with it's neighbors. You'll probably flip over forward. Wheat is the best choice.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-08-15T15:21:33.110" LastActivityDate="2014-08-15T15:21:33.110" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8163" PostTypeId="1" AcceptedAnswerId="11359" CreationDate="2014-08-15T15:20:11.547" Score="5" ViewCount="5598" Body="&lt;p&gt;The capacity of the Cessna 208 is &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_208_Caravan#Specifications_.28208B_Super_Cargomaster.29&quot; rel=&quot;nofollow&quot;&gt;stated&lt;/a&gt; as 9 passengers, or up to 14 with a FAR Part 23 waiver. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.10&quot; rel=&quot;nofollow&quot;&gt;FAR Part 23&lt;/a&gt; states that it applies to any aircraft with &quot;more than 10 occupants and that is intended for use in operations under Part 135&quot; (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr135_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;commuter or on-demand operations&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What part or parts of Part 23 require the C208 to have a waiver?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it common for waivers like this to be issued for the C208 or in similar situations on other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="19" LastEditDate="2014-12-24T15:18:01.253" LastActivityDate="2014-12-25T09:54:41.667" Title="Why might a Cessna 208 need a FAR Part 23 waiver?" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;&lt;cessna-208&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8164" PostTypeId="2" ParentId="8145" CreationDate="2014-08-15T18:19:54.880" Score="2" Body="&lt;p&gt;Under the Freedom of Information Act you can request these records from the FAA. Please read more about doing so here:&#xA;&lt;a href=&quot;http://www.faa.gov/foia/foia_request/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/foia/foia_request/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3208" LastActivityDate="2014-08-15T18:19:54.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8165" PostTypeId="1" CreationDate="2014-08-15T19:18:13.977" Score="6" ViewCount="1051" Body="&lt;p&gt;Is it possible that the CVR from a Cessna 560XL is just showing old records and nothing from the fatal accident when the plane crashed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I´m talking about &lt;a href=&quot;https://en.wikipedia.org/wiki/2014_Santos_Cessna_Citation_accident&quot; rel=&quot;nofollow noreferrer&quot;&gt;the airplane crash in Brazil, where a election candidate was killed&lt;/a&gt;. The investigation team said that the data in the CVR contained only old data and they could not pinpoint from when those recordings were.&lt;/p&gt;&#xA;" OwnerUserId="3209" LastEditorUserId="62" LastEditDate="2017-03-14T12:57:17.573" LastActivityDate="2017-03-14T15:16:55.210" Title="How can the CVR from a Cessna 560XL only contain old records and none from the fatal accident?" Tags="&lt;accidents&gt;&lt;cockpit-voice-recorder&gt;&lt;accident-investigation&gt;&lt;cessna-citation&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8166" PostTypeId="2" ParentId="8165" CreationDate="2014-08-15T19:35:07.503" Score="12" Body="&lt;p&gt;If the fuse was pulled between the previous flight and the crash then yes, the CVR can only record when it has power&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pulling the fuse or going behind the panel and cutting the wire will prevent it from recording.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-08-15T19:35:07.503" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8167" PostTypeId="2" ParentId="3056" CreationDate="2014-08-15T20:11:52.293" Score="4" Body="&lt;p&gt;&quot;Mark the tape&quot; is a hold-over term from way back when the recorders were reel-to-reel tapes. In order to mark the tapes, the controller would place a flight strip in the reel at the time of the occurence. As previously stated, with almost everything being digital, it's unnecessary.&lt;/p&gt;&#xA;" OwnerUserId="3210" LastActivityDate="2014-08-15T20:11:52.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8168" PostTypeId="1" AcceptedAnswerId="8170" CreationDate="2014-08-16T00:09:07.797" Score="13" ViewCount="52158" Body="&lt;p&gt;I know that pressure altitude for a certain pressure is defined to be the altitude in the standard atmosphere which has that pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I can't find whatever standard, regulation, or glossary officially defines it to be so. I tried to look in the AIM, the P/CG, a search of the FARs for &quot;pressure altitude&quot; wading through a ton of results, and what searchable partial copies of the US Standard Atmosphere of 1976 I could find. I don't have access to a copy of the ISO standard that defines the International Standard Atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know of an FAA, ICAO, or ISO document providing this definition?&lt;/p&gt;&#xA;" OwnerUserId="767" LastEditorUserId="19" LastEditDate="2015-01-12T19:29:09.137" LastActivityDate="2015-09-01T12:00:30.913" Title="Where is the official definition of pressure altitude?" Tags="&lt;altitude&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8169" PostTypeId="2" ParentId="8160" CreationDate="2014-08-16T03:59:39.707" Score="9" Body="&lt;p&gt;It depends on many factors. If you have plenty of height, you have time to consider many things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to react immediately, I would choose the field, you will probably cause significant damage to crop &amp;amp; aircraft, but will most likely walk away. I haven't tried it yet (:-)), but would imagine that it would be similar to landing the plane in water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a clear, straight road with no obstacles (people, traffic, hedges, power lines, etc) and reasonable wind angle, I would choose the road.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My grass, dirt, beach landing experience (which dates me) was mainly with Rallye (Minerva, MS. 880), Piper Colt, and various small Cessnas (150, 152, 172). While landing off pavement is much more fun, there are many more factors to consider, so if you have the opportunity, I would go for pavement...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(As an aside, we carried an electric fence in the plane to stop cattle from rubbing against the plane in grass fields.)&lt;/p&gt;&#xA;" OwnerUserId="3212" LastActivityDate="2014-08-16T03:59:39.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8170" PostTypeId="2" ParentId="8168" CreationDate="2014-08-16T07:29:06.823" Score="13" Body="&lt;p&gt;&lt;strong&gt;Pressure Altitude&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As defined by FAA in the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2003.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pressure altitude is the height above a standard datum plane (SDP),&#xA;  which is a theoretical level where the weight of the atmosphere is&#xA;  29.92 &quot;Hg (1,013.2 mb) as measured by a  barometer. An altimeter is essentially a sensitive barometer calibrated to indicate altitude in&#xA;  the standard atmosphere. If the altimeter is set for 29.92 &quot;Hg SDP,&#xA;  the altitude indicated is the pressure altitude. As atmospheric&#xA;  pressure changes, the  SDP may be below, at, or above sea level.&#xA;  Pressure altitude is important as a basis for determining airplane&#xA;  performance, as well as for assigning flight levels to airplanes&#xA;  operating at or above 18,000 feet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The pressure altitude can be determined by either of two  methods:&#xA;  1. Setting the barometric scale of the altimeter to 29.92 and reading the indicated altitude.&#xA;  2. Applying a correction factor to the indicated altitude according to the reported altimeter setting.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56396/FAA%20P-8740-02%20DensityAltitude[hi-res]%20branded.pdf&quot; rel=&quot;noreferrer&quot;&gt;More info from the FAA here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;em&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&amp;amp;rgn=div5#se14.2.91_1217&quot; rel=&quot;noreferrer&quot;&gt;Docket No. 18334, 54 FR 34304, Aug. 18, 1989, as amended by Amdt. 91-314, 75 FR 30193, May 28, 2010&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.217 Data correspondence between automatically reported pressure altitude data and the pilot's altitude reference.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may operate any automatic pressure altitude reporting equipment associated with a radar beacon transponder—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) When deactivation of that equipment is directed by ATC;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Unless, as installed, that equipment was tested and calibrated to transmit altitude data corresponding within 125 feet (on a 95 percent probability basis) of the indicated or calibrated datum of the altimeter normally used to maintain flight altitude, with that altimeter referenced to 29.92 inches of mercury for altitudes from sea level to the maximum operating altitude of the aircraft; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Unless the altimeters and digitizers in that equipment meet the standards of TSO-C10b and TSO-C88, respectively.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may operate any automatic pressure altitude reporting equipment associated with a radar beacon transponder or with ADS-B Out equipment unless the pressure altitude reported for ADS-B Out and Mode C/S is derived from the same source for aircraft equipped with both a transponder and ADS-B Out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO has described how they calculate Pressure Altitude&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sco3H.jpg&quot; alt=&quot;Pressure Altitude versus Pressure&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://fisicaatmo.at.fcen.uba.ar/practicas/ISAweb.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://weatherfaqs.org.uk/book/export/html/174&quot; rel=&quot;noreferrer&quot;&gt;In relation to QNE:&lt;/a&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the ISA mean sea level standard pressure of 1013.2 hPa is set on&#xA;  an aircraft altimeter subscale, the height so indicated upon landing&#xA;  at an airfield is known as the QNE reading. More widely, this is also&#xA;  the PRESSURE ALTITUDE, which is alternatively defined as the height of&#xA;  any level in the international standard atmosphere (ISA-see above),&#xA;  above the level corresponding to a pressure of 1013.2 hPa.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.newbyte.co.il/calc.html&quot; rel=&quot;noreferrer&quot;&gt;Here is a free tool&lt;/a&gt; to calculate standard atmospheric conditions (ISA) at a given geometric or pressure altitude and ambient temperature.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="2143" LastEditDate="2015-01-12T21:57:44.020" LastActivityDate="2015-01-12T21:57:44.020" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8172" PostTypeId="1" AcceptedAnswerId="8173" CreationDate="2014-08-16T14:51:12.057" Score="12" ViewCount="4335" Body="&lt;p&gt;This looks contra-intuitive: if a plane can take off and fly horizontally, what prevents it from descending and touching down to the runway with the required small vertical speed? &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="2171" LastEditDate="2014-11-20T02:27:32.243" LastActivityDate="2015-06-10T18:50:55.313" Title="Why safe take off weight exceeds the safe landing weight?" Tags="&lt;landing&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8173" PostTypeId="2" ParentId="8172" CreationDate="2014-08-16T15:01:17.260" Score="27" Body="&lt;p&gt;Because when taking off you go from 0 vertical speed to a positive rate of climb all by way of the wings (the force on the gear will decrease over time to 0 when airborne). But while landing you will go from negative rate of climb to 0 vertical speed. Most of that will be absorbed by the gear (the force on the gear will spike and then settle to only the weight of the aircraft). After touching down there is also the braking force exerted on the gear which is proportional to the mass of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is that spike+braking force that the engineers are worried about when calculating max landing weight.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-08-16T15:25:41.727" LastActivityDate="2014-08-16T15:25:41.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8174" PostTypeId="1" CreationDate="2014-08-16T19:32:53.430" Score="6" ViewCount="303" Body="&lt;p&gt;I am planning a flight to Le Touquet (LFAT) in France next week, I've been told that ATC is not open all days so I've checked the NOTAMS. This seems applicable but I'm not sure I'm interpreting it correctly:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;LFFA-B3753/14  A) LFAT  LE TOUQUET PARIS PLAGE B) 2014 Aug 01  07:00&#xA;  C) 2014 Aug 31  23:59 E) FIRE AND RESCUE HOURS OF SERVICE: &#xA;  0700-0900 1500-1800    : LEVEL 2 &#xA;  0900-1500              : LEVEL 4 &#xA;  SAUF 15,16,22,23,26-29 : LEVEL 2 ATS HOURS OF SERVICE LEVEL 5 O/R, PPR 24H&#xA;  TO OPR  PHONE: +33(0)3 21 05 03 99  FAX: +33(0)3 21 05 59 34 LEVEL 1&#xA;  OUTSIDE ATS HOURS OF SERVICE.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think what this is saying is that it is operating at level 2 ATC hours of service except  (Sauf) on the 15,16,22,23,and 26-29th of August, but level 1 all other hours. I think what this means is that next week on weekdays it will be operating at level 2 hours of service. I also think that level 2 means 07-09:00Z and 15-18:00Z, and during this service level 5 will be offered, but all other times level 1 will be offered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I think that if I go on those days listed and times listed the tower will be open, otherwise it will be closed (I'm assuming that's what level 1 means), and that I will need to use French non-towered procedures, including French calls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to know if I've made the right interpretation, and if there's a source of information about ATC levels in France. I've scoured the web for a couple of hours with no result. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what are level 2 hours of service, and what service is provided? What is provided with level 1 ATS? &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="572" LastEditDate="2015-02-19T09:03:37.450" LastActivityDate="2015-02-19T09:03:37.450" Title="What do the levels stand for in French Air Traffic Service Levels?" Tags="&lt;air-traffic-control&gt;&lt;notam&gt;&lt;france&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8176" PostTypeId="2" ParentId="8160" CreationDate="2014-08-17T01:03:20.830" Score="16" Body="&lt;p&gt;As a glider pilot, I think a lot about landing in fields, and do it moderately routinely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has been commented, the answer to &quot;where to go&quot; depends dramatically on the aircraft that you're in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cornfield is a almost-guaranteed crash for a fixed undercarriage nose-wheel aircraft.    But it's probably a nice soft bed for a jumbo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we limit ourselves to aircraft with less than two engines, the main factors that come into play are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Retractable under carriage&lt;/li&gt;&#xA;&lt;li&gt;Nose wheel or tail dragger&lt;/li&gt;&#xA;&lt;li&gt;High or low wing configuration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Retractable undercarriage affects your choice of outlanding, because it gives you the opportunity to take the wheels away from a grabby crop (or water).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nose wheel or tail dragger affects your choice because it affects which part of the aircraft will hit the grabby crop first, and affects the centre of gravity of the configration at the time this happens.    You want tail-first low CofG in a grabby crop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High or low wing configuration affects the choice because a low wing configuration means that the posts on the side of a single lane road are significant, and a crop can grab them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;types&quot; of outlanding choices that you have fall into categories that include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Empty fallow field  &lt;/li&gt;&#xA;&lt;li&gt;Stocked field (and whether the stock is spread out or in one corner) &lt;/li&gt;&#xA;&lt;li&gt;Recently harvested wheat - low&lt;/li&gt;&#xA;&lt;li&gt;Recently harvested wheat - high&lt;/li&gt;&#xA;&lt;li&gt;Corn/canola&lt;/li&gt;&#xA;&lt;li&gt;Vines&lt;/li&gt;&#xA;&lt;li&gt;Road&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each of these (and choices similar) have different characteristics, and the choice &quot;chart&quot; for each is different depending on the aircraft configuration variables mentioned above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may surprise you that corn and canola are grouped together, given that corn has massive cobs, and canola does not.    But actually the major factor for this type of crop is it's depth and &quot;grabby-ness&quot;.   Canola is only marginally better to land in than corn, because it is not as deep.    But is is just as grabby.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why corn/canola is a certified crash for a nose-wheel fixed undercarriage aircraft.   Unless you are a gun pilot with a cunning plan to get around it - in which case your approach will be anything but normal - that crop is going to grab your mainwheels and you're going in nose first: bang.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a taildragger, you have the opportunity to come in nose-high and have the tail-wheel grab first.   In this instance, depending on the stall-speed of your aircraft (IE how fast you are going when this happens) it might turn into a &quot;landing&quot; instead of a &quot;crash&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you have low wings, then you're still in trouble, because the chances are quite reasonable that this grabby crop will grab a wingtip, and boom - crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a road, if you have high wings, then you are in good shape.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You asked &quot;should a road ever be considered?&quot;.  ONLY IF there is NO traffic.    In a small aircraft, with less than a handful of passengers, you have no right to risk the life of people travelling on a road, which is what you will be doing if you put down on it while they are driving on it.   If you suprise just a single car doing country road speeds, that driver can end up rolled in a ditch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So ONLY if I had a high wing aicraft with a deserted straight road would I consider that - and then it is actually quite attractive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Edit: in case it isn't obvious, vines are death).&lt;/p&gt;&#xA;" OwnerUserId="945" LastEditorUserId="945" LastEditDate="2014-08-17T02:06:44.537" LastActivityDate="2014-08-17T02:06:44.537" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8177" PostTypeId="1" AcceptedAnswerId="8181" CreationDate="2014-08-17T02:26:13.270" Score="31" ViewCount="17893" Body="&lt;p&gt;So far as I am aware, in a fixed wing aircraft having side-by-side seating and  dual controls but only a single set of instruments, those instruments are always positioned in front of the left seat. Even when an aircraft (such as commercial air transport) is fitted with dual instruments, the left seat is designated as the &quot;pilot-in-command&quot; or &quot;captain's&quot; position. This &quot;left-seat as principal&quot; designation appears to hold true for any fixed wing aircraft from a Cessna 152 to a Boeing 747, in all jurisdictions of manufacture and operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a helicopter, the situation appears to be reversed - the &quot;pilot in command&quot; appears to always occupy the right seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true, always, or is it an observational bias? Is this simply convention or is it specified by regulation? What would account for exceptions, if any?&lt;/p&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="167" LastEditDate="2015-01-05T19:20:55.367" LastActivityDate="2020-07-16T00:21:16.850" Title="Why is the PIC position for helicopters the right seat, rather than the left seat as in airplanes?" Tags="&lt;helicopter&gt;&lt;fixed-wing&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8179" PostTypeId="2" ParentId="2317" CreationDate="2014-08-17T03:10:02.390" Score="20" Body="&lt;p&gt;An AOA vane (like what you have shown) works by aligning itself with the local airflow, like an arrow.  The angle to some reference line (normally aircraft fuselage horizontal) is then measured with a potentiometer/RVDT/etc.  This is the local angle of attack.  Often the local angle of attack is converted to aircraft angle of attack through a calibration curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most transport airplanes have 2 vanes.  If either vane shows an angle of attack that is approaching stall, the stall warning will alert the pilot(s) that stall is near.  If both AOA vanes are at the stall AOA, a stick pusher will activate to alleviate the aerodynamic stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AOA values are never averaged.  Depending on the AOA computer, logic is used to determine if one of the vanes is giving bad data. &lt;/p&gt;&#xA;" OwnerUserId="3220" LastActivityDate="2014-08-17T03:10:02.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8180" PostTypeId="2" ParentId="8081" CreationDate="2014-08-17T03:37:40.187" Score="9" Body="&lt;p&gt;Variable ratio gearing in road vehicles (cars, bicycles, etc.) is required to match the speed and torque capabilities of the prime mover (gas engine, human leg power, etc.) to the speed and torque requirements of the road wheels over varying conditions of vehicle speed, road grade, etc. Basically, there is a need (or at least benefit) to vary the mechanical advantage between prime mover and driving wheel(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The prime mover (jet or piston engine, turbofan or propeller) in an aircraft produces thrust largely independent of airspeed, so for many aircraft, variable ratio gearing is not required. For propeller aircraft, it can be beneficial to vary the mechanical advantage between the powerplant and the airstream. It is done, not by variable ratio gearing, but by &lt;a href=&quot;http://en.wikipedia.org/wiki/Variable_pitch_propeller&quot;&gt;varying the pitch of the propeller&lt;/a&gt;. For one thing, varying the pitch can vary mechanical advantage over a continuous range where a gearbox is limited to a few fixed steps. For another, gearing systems add a lot of weight. Changing gears would mean disconnecting the engine from the propeller as a different gear ratio is selected - that's a big reliability/safety issue, and for a piston engine, couldn't even be workable. Piston engines can't run without a flywheel; in an aircraft, the propeller serves as the flywheel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, where the benefits of variable mechanical advantage justify the added cost, weight, and complexity, a variable pitch propeller is fitted. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some variable pitch systems provide a lever which directly control the pitch - the pilot moves the lever over a range between &quot;fine&quot; (engine gets more mechanical advantage, suitable for take-off) and &quot;coarse&quot; (engine has less mechanical advantage, suitable for cruise).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other variable pitch systems provide a lever which selects a target engine RPM. The pitch control system continously adjusts the propeller pitch in an attempt to maintain the selected RPM. The pilot uses the throttle to increase or decrease engine thrust, and the pitch control to optimize the engine RPM for the operating conditions (take off, climb, cruise, etc.). On a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-32#PA-32-300&quot;&gt;PA32-300&lt;/a&gt;, for example, the pitch control would be fully forward (max RPM) for taxi, take-off, and initial climb-out, but would be adjusted back somewhat for cruise to reduce engine RPM (and fuel consumption).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could think of the pitch control systems I've described as analogous to a manual and an automatic transmission respectively, but the analogy is a loose one at best.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="3218" LastEditDate="2014-08-17T17:39:01.193" LastActivityDate="2014-08-17T17:39:01.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8181" PostTypeId="2" ParentId="8177" CreationDate="2014-08-17T04:20:59.217" Score="31" Body="&lt;p&gt;The reason is both historical and operational.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first mass produced helicopter was the Sikorsky R-4.  It had a single collective located between the two pilot seats, so by necessity, the person on the right would control the cyclic with their right hand, and the person on the left would control the cyclic with their left (because their right is needed on the collective).  The cyclic in the R-4 was very difficult to manipulate and required a lot of strength and coordination.  Since the vast majority of student helicopter pilots were right handed, they sat in the right seat, allowing them to use their dominant hand on the cyclic.  Thus, the first generation of helicopter pilots all sat in the right seat, since they all learned on the R-4 (or the R-6).  That's how traditions begin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The operational applications of sitting in the right seat relate to the inherent instability of a helicopter. A helicopter pilot rarely wants to let go of the cyclic, as it often requires continuous control inputs, especially when hovering. The collective, on the other hand, does not need to be monitored as closely and can be held steady with a friction adjustment, so that hand is occasionally free to manipulate things like radios and other equipment, which are located in the center of the cockpit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most helicopters these days have a collective for each seat, located on the left, so the pilot wants to use the hand in the middle of the cockpit to work the radios and things.  Hence, they sit on the right side, which places the collective hand in the middle of the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read a longer article about this: &lt;a href=&quot;http://www.airspacemag.com/need-to-know/why-do-helicopter-pilots-sit-in-the-right-seat-243212/&quot;&gt;Why do helicopter pilots sit in the right seat?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="66" LastEditorUserId="3504" LastEditDate="2015-01-05T18:03:19.313" LastActivityDate="2015-01-05T18:03:19.313" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8182" PostTypeId="1" AcceptedAnswerId="8183" CreationDate="2014-08-17T08:25:33.423" Score="14" ViewCount="5096" Body="&lt;p&gt;As a passenger, what happens / can happen if you refuse to fasten your seatbelt when you are told to, either during take off/landing or (bad) turbulences?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've recently read a Facebook post that supposedly described such a situation. It didn't give many details, so that's why I'm here.&lt;/p&gt;&#xA;" OwnerUserId="3221" LastActivityDate="2020-09-01T10:15:34.970" Title="What if you refuse to fasten your seatbelt?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;takeoff&gt;&lt;turbulence&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8183" PostTypeId="2" ParentId="8182" CreationDate="2014-08-17T10:03:30.990" Score="22" Body="&lt;p&gt;In the US it is an offence under federal law.&lt;/p&gt;&#xA;&lt;p&gt;A loose 180lb/80kg projectile inside an aircraft is a threat to other passengers during turbulence, in the worst cases of passenger misbehaviour cabin staff can and have forcibly restrained passengers and/or diverted to a nearby airport to have the passenger deplaned and sometimes arrested.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smartertravel.com/photo-galleries/editorial/seven-ways-to-get-kicked-off-a-plane.html?id=243&amp;amp;photo=27203&amp;amp;max_photos=7&quot; rel=&quot;noreferrer&quot;&gt;Seven Ways to Get Kicked Off a Plane&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.breakingworldnewstoday.com/2013/08/b1893.html&quot; rel=&quot;noreferrer&quot;&gt;Family kicked off plane&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A 3-year-old, who refused to use his safety belt, caused a flight to be delayed after his father could not get him locked in his seat belt on board an Alaska Airlines plane.&lt;/p&gt;&#xA;&lt;p&gt;The pilot returned to the gate on Saturday and asked the father and child to get off the plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.farecompare.com/travel-advice/why-you-need-to-wear-your-seatbelt-on-a-plane/&quot; rel=&quot;noreferrer&quot;&gt;Why you need to wear a seatbelt&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For passengers who refuse to wear seatbelts when the sign is illuminated and who are disruptive to the crew, the FAA can impose a maximum fine of $25,000.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-17T10:12:22.230" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8184" PostTypeId="2" ParentId="8177" CreationDate="2014-08-17T20:18:30.387" Score="10" Body="&lt;p&gt;The thrust from the tail rotor on a counter-clockwise spinning helicopter tends to create a translational shift to the right which is countered by rigging the cyclic neutral position to be slightly left of centre. This results in the left skid &quot;hanging low&quot;.  So as not to make this skid even lower, it is a practical reason to sit a solo occupant on the right.  Even when solo, the left skid still hangs visibly lower.  Some light helicopters are prohibited from solo flight in the left seat (e.g. R22) as it would be possible to run out of cyclic authority in some circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the lateral CG chart for the R-22. As you can see, the right side of the helicopter has a greater lateral CG envelope than the left, which is why the solo pilot always sits on the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QpvoY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The opposite is true for clockwise spinning main rotors.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-05-28T21:34:11.510" LastActivityDate="2015-05-28T21:34:11.510" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8185" PostTypeId="2" ParentId="1219" CreationDate="2014-08-17T21:05:51.107" Score="-4" Body="&lt;p&gt;I have landed at Cabinda and Angola.&#xA;I have made many landings there. They can be tricky, but local pilots use CPP, reverse thrust and wheel braking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One pilot has mentioned that disc pads are very expensive, so you want to wear them down as little as possible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same pilot mentioned that reverse thrust can also damage engines, no matter whether CPP or jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am still flying cessna's.&lt;/p&gt;&#xA;" OwnerUserId="3225" LastEditorUserId="2171" LastEditDate="2014-08-18T03:33:11.810" LastActivityDate="2014-08-18T03:33:11.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8186" PostTypeId="2" ParentId="8081" CreationDate="2014-08-18T00:53:50.173" Score="5" Body="&lt;p&gt;Another factor not mentioned is that in land vehicles gears are used for travelling slowly, so the engine can stay in its operating range.  But an airplane won't fly below a certain minimum stall speed, so gears are pretty pointless.  In a typical small plane, your range of flying speeds (say 65-150 mph) corresponds to an engine speed range of roughly 1700-2500 rpm.  If you throttle back to idle (or your engine quits), you basically have to glide, trading altitude for the airspeed needed to stay above stall speed.&lt;/p&gt;&#xA;" OwnerUserId="3226" LastActivityDate="2014-08-18T00:53:50.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8187" PostTypeId="1" AcceptedAnswerId="8190" CreationDate="2014-08-18T09:08:46.587" Score="7" ViewCount="2256" Body="&lt;p&gt;I get that ,the max altitude it was flown to was 70 ft. after its 3rd test taxi.I also am aware that even this was done to prove a point. But,why was there no attempt later on to complete a test flight and to check if it was Air worthy? Was no one curious at all ?  &lt;/p&gt;&#xA;" OwnerUserId="3229" LastEditorUserId="700" LastEditDate="2014-08-19T08:02:33.590" LastActivityDate="2014-08-19T08:02:33.590" Title="Why was a complete test flight of Hughes Hercules H-4 (Spruce Goose) never undertaken?" Tags="&lt;takeoff&gt;&lt;flight-testing&gt;&lt;seaplane&gt;&lt;aircraft-heavy&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8188" PostTypeId="1" CreationDate="2014-08-18T09:09:46.937" Score="37" ViewCount="45740" Body="&lt;p&gt;I noticed that even when my phone is in &quot;airplane mode&quot;, I can still use the GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically a GPS receiver just receives data, so I &lt;em&gt;guess&lt;/em&gt; it would not jam anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary, &lt;a href=&quot;http://support.apple.com/kb/ht1355&quot; rel=&quot;noreferrer&quot;&gt;on the iPhone airplane mode disables GPS&lt;/a&gt;, so it means that at least a few engineers at Apple are worried about people using GPS in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it really OK to use my phone's GPS in plane, as a passenger of a typical commercial flight?&lt;br&gt;&#xA;&lt;em&gt;(when use of electronic device in airplane mode is allowed, obviously)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O07tb.png&quot; alt=&quot;GPS in airplane mode&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1087" LastEditorUserId="1087" LastEditDate="2018-02-11T09:37:29.513" LastActivityDate="2018-02-11T09:37:29.513" Title="&quot;Airplane mode&quot; does not disable GPS... is it safe to use GPS in flight?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;gnss&gt;" AnswerCount="9" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8189" PostTypeId="2" ParentId="8188" CreationDate="2014-08-18T09:19:12.703" Score="1" Body="&lt;p&gt;The big question that is raised here is part of the great urban myth of do electronics actually play up with an aircraft's avionics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My simple answer to your question is if the airline or Pilot in Command has asked you to shut off all electrical devices, there is no exception, it must be turned off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My realistic answer - I've sat on the phone, flying around using my Bose Headset, and never had an issue. In Australia, there is no law against use of electronic devices except during refueling. Not sure about the rest of the world.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2014-08-18T09:19:12.703" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8190" PostTypeId="2" ParentId="8187" CreationDate="2014-08-18T10:06:52.127" Score="8" Body="&lt;p&gt;By the time the government had pulled the plug on the program. Even that hop got Hughes into trouble because they had been expressly forbidden from taking off (he got off on a technicality, claiming it'd been unintentional, unexpected behaviour from an experimental machine, etc.).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;If it had been anyone except Hughes I'm pretty sure the H4 would have been destroyed rather than preserved as a museum piece, the US government was that intent on killing the project there and then. They had a lot of air bases with long runways to find a purpose for, and long range air travel was an excellent purpose. They also wanted to find customers for the thousands of surplus transport aircraft (and bombers to be converted to that role). So getting rid of the traditional way to fly intercontinental, the flying boat, was important.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Were people curious? No doubt. But they also were budget conscious, the H4 had no more military application so there was no money coming out of the Pentagon. It had no civilian application, as for large payload ships are cheaper and for small, fast payloads it was too large. So even if there had not been active hostility towards the flying boat concept at the time from people with the power to release or deny budgets, there would have been little point in implementing an expensive flight test program (which usually requires multiple vehicles...) for an aircraft for which it was highly unlikely there would ever be any peacetime orders.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Of course 50 years later the idea was kinda revived with a short period of interest in Wing In Ground effect vehicles to fly troops and supplies over the feared Soviet submarine fleet in the Atlantic. But that didn't start up until near the demise of that threat in the 1990s and nothing ever made it past concept drawings (except paradoxically a few Soviet craft in the Caspian and Black Sea regions, the Ekranoplans).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;I've little doubt the H4 would have worked as advertised, seeing it it looks sound in design, basically a scaled up B314. But there was just no market for it. It was an example of too big, too late. &lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="1677" LastEditDate="2014-08-19T04:07:28.173" LastActivityDate="2014-08-19T04:07:28.173" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8191" PostTypeId="2" ParentId="8188" CreationDate="2014-08-18T10:15:12.790" Score="36" Body="&lt;p&gt;theoretically? GPS IS receive only. There's no way to talk to the GPS satellite network except using the big antennas of the network owners (the US DoD) and the communications are no doubt heavily encrypted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, does that mean it's &quot;safe&quot; for aircraft electronics. Any receiving antenna does have an EM field around it, so if you believe the myth that those electronics are so sensitive and easy to jam that any EM field at all causes them to malfunction the answer is an obvious NO.&lt;br/&gt;&#xA;But that myth is just that, a myth. If they were so sensitive, that old walkman you were using in the 1980s during flights would have brought down that aircraft. Because not only do antennas have EM fields around them, any electrical device that's turned on has one (in fact any electrical cable with a current flowing through it has one, including the headphone cord for the in flight entertainment system).&lt;br/&gt;&#xA;And that GPS system in your cellphone uses a lot less power than that walkman, has a far weaker field surrounding it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course it's theoretically possible that a strong enough EM field might interfere with the electronics in an aircraft, but then to you'd need just the right signal. Which would indicate you need intent (or incredible bad luck)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effectively the GPS in your cellphone is a lower powered version of the GPS receiver in the belly of the aircraft, which has its own antenna (which no doubt has a similar field around it, but of higher strength).&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="1467" LastEditDate="2016-08-01T21:37:39.023" LastActivityDate="2016-08-01T21:37:39.023" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="8192" PostTypeId="1" AcceptedAnswerId="8195" CreationDate="2014-08-18T10:19:55.217" Score="9" ViewCount="697" Body="&lt;p&gt;In Wikipedia's description of one of air crashes (probably Thai Airlines, if I recall correctly), I found a remark saying something like that: &quot;Crew decided to go around, but apparently decided to undertake this procedure manually&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm surprised. &quot;Apparently&quot;? Making go around manually is something odd? Do we have any automated (autopilot-based) go around procedures or techniques in common use? I was always more than sure, that procedures like go around or touch-and-go are &lt;strong&gt;always&lt;/strong&gt; made manually by a pilots.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="14957" LastEditDate="2016-09-18T07:59:27.850" LastActivityDate="2016-09-18T07:59:27.850" Title="Is there any automated go-around procedure?" Tags="&lt;approach&gt;&lt;instrument-procedures&gt;&lt;go-around&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8193" PostTypeId="2" ParentId="8192" CreationDate="2014-08-18T10:33:41.790" Score="1" Body="&lt;p&gt;Normally on a &quot;go around&quot; the pilot flies the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfield_traffic_pattern&quot; rel=&quot;nofollow&quot;&gt;airfield traffic pattern&lt;/a&gt; and attempts to land again, usually after a visual approach. This is done manually as far as I know. The &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Missed_approach&quot; rel=&quot;nofollow&quot;&gt;missed approach&lt;/a&gt;&quot; which is a published instrument procedure, is described in the aircraft's FMS (for an FMS equipped aircraft) and can be activated by the crew and flown automatically. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I am not a professional this is as afar as I know. More details (about rules regulations e.t.c.) can be provided by others. But unless you provide more details about the accident, I think that little can be explained for the case.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2014-08-18T10:33:41.790" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8195" PostTypeId="2" ParentId="8192" CreationDate="2014-08-18T11:40:50.843" Score="9" Body="&lt;p&gt;For go-around, several things have to be done in the moment the decision is taken:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Apply full power (obviously),&lt;/li&gt;&#xA;&lt;li&gt;disconnect autopilot glide-slope mode,&lt;/li&gt;&#xA;&lt;li&gt;disarm spoilers and retract them if they are extended,&lt;/li&gt;&#xA;&lt;li&gt;disarm autobrakes and&lt;/li&gt;&#xA;&lt;li&gt;in some aircraft reduce flaps.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Modern airliners, and some smaller aircraft, have a method for doing all of these at once via the &lt;a href=&quot;http://en.wikipedia.org/wiki/Takeoff/Go-around_switch&quot;&gt;TO/GA button&lt;/a&gt;. On Airbus aircraft it is done by just advancing the thrust levers to the TO/GA (full power) position, but on Boeing aircraft and many other types it is a separate button on or near the thrust levers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the crew &quot;apparently decided to undertake this procedure manually&quot; it means they moved the thrust levers forward and started changing the other things. And probably missed one of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;I am not sure whether lateral mode remains under automatic control or not and it probably depends on aircraft as some can connect autopilot to only roll or only pitch and others don't. Pitch control is manual immediately after go-around in either case.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The last flap setting usually adds a lot of drag and a little lift. In some types the drag is too large and the flaps have to be retracted to the last usable position. On other aircraft they can be used in any position and have to be left were they were to avoid loosing lift.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="6" LastEditDate="2014-08-18T17:58:01.703" LastActivityDate="2014-08-18T17:58:01.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8196" PostTypeId="2" ParentId="8147" CreationDate="2014-08-18T12:17:29.003" Score="0" Body="&lt;p&gt;Fuel dumping is done by many types of Aircraft(fighter etc.) it is not limited to the role(cargo, passenger etc.). Although the purpose may be same.(Sometimes its done to reduce the load, to avoid any accident).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a fighter plane fuel is dumped to reduce the weight and increase the distance to cover(the weapons it carries already has tons of weight on the plane). This could be the same in passenger but situations may vary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel dumping is really a serious threat to the environment or the biological impact  especially if it's dumped in the water(causes damage to maritime species and irreversible damage to the coral reefs if present). &lt;/p&gt;&#xA;" OwnerUserId="3012" LastActivityDate="2014-08-18T12:17:29.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8197" PostTypeId="1" AcceptedAnswerId="8231" CreationDate="2014-08-18T12:43:28.983" Score="10" ViewCount="1210" Body="&lt;p&gt;As a VFR student pilot, I'm still developing a pre cross-country flight routine. Weather has without a doubt been the most difficult portion of my preflight information to digest, as there are so many different sources and formats for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the generally acknowledged best practices (and sources) for assembling a complete understanding of all weather pertaining to a cross-country flight in a timely manner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: This question is primarily focused within the continental United States, although answers pertaining to any region are more than welcome.&lt;/p&gt;&#xA;" OwnerUserId="2984" LastEditorUserId="64" LastEditDate="2014-08-19T17:57:23.410" LastActivityDate="2014-08-19T19:11:24.157" Title="What are the best practices for gathering preflight weather and information?" Tags="&lt;usa&gt;&lt;weather&gt;&lt;preflight&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8198" PostTypeId="2" ParentId="8188" CreationDate="2014-08-18T13:23:33.840" Score="4" Body="&lt;p&gt;Having done this before while in flight (I was trying to see if the GPS would be disabled as I had heard commercial GPS systems are designed to not work after a certain velocity).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can confirm the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It works, but its not as smooth or accurate as the in-flight display. There are many reasons for this - one is that due to the size of the screen and the distance covered (and possibly, the scale), each refresh interval has a large gap. In other words, your phone will refresh, and your pointer/pin on the map will jump around a lot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It takes a long time to get a fix; I could only get 5 satellites (normally the receiver picks up 8+) - again, due to the speed of the aircraft and the fact that when you are not in airplane mode, other radios are used to approximate your position.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it harmful to the overall flight systems? Consider that on an average large airliner, not everyone remembers to turn off their devices, I think having a passive thing such as a GPS running - in the long term, would not be harmful to the electronics of the aircraft. I think an electric shaver that you can use freely would cause more problems.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-08-18T13:23:33.840" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8199" PostTypeId="1" AcceptedAnswerId="8203" CreationDate="2014-08-18T15:15:16.020" Score="31" ViewCount="14700" Body="&lt;p&gt;Most pictures of airliner's nose sections show small dark tube- or fin-shaped instruments sticking out of the fuselage below the cockpit windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example this Airbus A350 shows them well:&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Airbus/Airbus-A350-941/2395775/&amp;amp;sid=81908f0207571b7cfc98bcd2aded053c&quot; title=&quot;Airlines.net&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wmLP5.jpg&quot; alt=&quot;A350 nose section&quot;&gt;&lt;/a&gt; &#xA;Source: &lt;a href=&quot;http://www.airliners.net/photo/Airbus/Airbus-A350-941/2395775/&amp;amp;sid=81908f0207571b7cfc98bcd2aded053c&quot; title=&quot;Airlines.net&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airliners (737, A380, 787) carry similar instruments at the front.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure Google would be able to tell me if only I knew how to correctly phrase my question, but...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These instruments sticking out of the fuselage, what purpose do they serve?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="3151" LastEditDate="2014-08-28T07:03:44.533" LastActivityDate="2019-08-28T14:25:59.627" Title="Which external instruments are visible on the A350's nose section?" Tags="&lt;aircraft-systems&gt;&lt;measurement&gt;&lt;airbus-a350&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8200" PostTypeId="1" AcceptedAnswerId="8202" CreationDate="2014-08-18T15:15:42.933" Score="6" ViewCount="1601" Body="&lt;p&gt;What are the valid set of enumerated states for landing gear?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My current working set is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;DOWN&lt;/li&gt;&#xA;&lt;li&gt;DOWN &amp;amp; LOCKED&lt;/li&gt;&#xA;&lt;li&gt;STOWED&lt;/li&gt;&#xA;&lt;li&gt;STOWED &amp;amp; LOCKED&lt;/li&gt;&#xA;&lt;li&gt;INOPERATIVE&lt;/li&gt;&#xA;&lt;li&gt;CYCLING_UP&lt;/li&gt;&#xA;&lt;li&gt;CYCLING_DOWN&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, are there any definitions in which UP is distinct from STOWED?  (I can't find any.)&lt;/p&gt;&#xA;" OwnerUserId="3235" LastEditorUserId="19" LastEditDate="2017-01-20T08:59:40.650" LastActivityDate="2017-01-20T08:59:40.650" Title="What are the states that the landing gear can be in?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8201" PostTypeId="1" AcceptedAnswerId="8205" CreationDate="2014-08-18T15:23:03.597" Score="12" ViewCount="8635" Body="&lt;p&gt;Crop duster aircraft operate much differently than most other aircraft. Are there special rules that apply to their operation? Specifically, are there rules about how close they can fly to structures, terrain, or vehicles?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2017-07-15T03:25:31.007" Title="What are the flight rules for crop dusters?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8202" PostTypeId="2" ParentId="8200" CreationDate="2014-08-18T15:31:21.543" Score="15" Body="&lt;p&gt;Any instruments always show only three states:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Down and locked (green)&lt;/li&gt;&#xA;&lt;li&gt;Up/stowed (extinguished)&lt;/li&gt;&#xA;&lt;li&gt;Anywhere in between (red)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you want to simulate it, remember that while the pilot can only command one of the two end states, the transition is a continuous process and you need to represent exact position of the gear in each frame of the simulation. So you need a value that will smoothly transition between 0 (stowed) and 1 (down and locked). Any value in between will indicate red on the instrument, but will correspond to different state of the gear animation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exact steps during gear extension (and in reverse for raising) differ by aircraft, but generally the animation will have three parts that you will map to suitable ranges of the gear state value:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;opening the gear door,&lt;/li&gt;&#xA;&lt;li&gt;lowering the gear and&lt;/li&gt;&#xA;&lt;li&gt;closing the main gear door.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The last step actually complicates issues a bit, because the gear is already down and locked when the main gear door close and in case you do gravity extension the main gear door remain open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the suggested mapping is actually something like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;opening the gear door 0.0 to 0.3&lt;/li&gt;&#xA;&lt;li&gt;lowering the gear 0.4 to 1.0&lt;/li&gt;&#xA;&lt;li&gt;closing the main gear door 1.1 to 1.4&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When you extend the gear normally, the value will transition up to 1.4 (and show green past 1.0), when you extend the gear via alternate mechanism (gravity drop), it will only transition to 1.0. If you want to simulate alternate extension, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tweak the values to make the animation look appropriate. The relative speed differs by aircraft. Some aircraft also don't have gear door (e.g. 737 only has one panel that is attached to the strut on main wheels; it still does have nose gear door, so the process will be slightly different for each leg).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which leads me to note, that if you want to simulate failures, you definitely need separate value for each leg, because some failures, like &lt;a href=&quot;http://avherald.com/h?article=469338e0&quot;&gt;jammed actuator&lt;/a&gt;, only affect one gear. Also in reality the legs take slightly different time to extend, so you can add some variability to the transition time if you wish.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-08-18T18:06:16.903" LastActivityDate="2014-08-18T18:06:16.903" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8203" PostTypeId="2" ParentId="8199" CreationDate="2014-08-18T15:59:31.270" Score="37" Body="&lt;p&gt;Here's a better picture showing all probes, and labeled:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eH5rR.jpg&quot; alt=&quot;A350&quot;&gt;&#xA;&lt;em&gt;&lt;br/&gt;&lt;sub&gt;&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/photos/aircraft/a350%20family/a350-900/A350_XWB_paint_shop_rollout_8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link to original, high-resolution, unnumbered picture&lt;/a&gt;&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ice detector&lt;/li&gt;&#xA;&lt;li&gt;Multi-function probe &lt;sup&gt;1&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;Static port&lt;/li&gt;&#xA;&lt;li&gt;TAT probe&lt;/li&gt;&#xA;&lt;li&gt;Side-slip vane&lt;/li&gt;&#xA;&lt;li&gt;Pitot probe&lt;/li&gt;&#xA;&lt;li&gt;Angle-of-attack vane&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Airbus.com has a &lt;a href=&quot;https://www.airbus.com/content/dam/corporate-topics/publications/backgrounders/techdata/aircraft_characteristics/Airbus-Commercial-Aircraft-AC-A350-900-1000.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PDF&lt;/a&gt; &lt;em&gt;(pdf page 125)&lt;/em&gt; about the various probes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;br/&gt;&#xA;As the name suggests, the multi-function probes record different types of data. Here are &lt;a href=&quot;http://www.memscap.com/applications-and-market-segments/aerospace-and-defense/smart-probes&quot; rel=&quot;nofollow noreferrer&quot;&gt;more details&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The piloting of any aircraft involves knowing the relative speed of&#xA;  the aircraft with respect to the airflow surrounding it, that is to&#xA;  say to the relative wind. This speed is determined with the aid of&#xA;  sensors of the static pressure Ps, of the total pressure Pt and of the&#xA;  angle of incidence “alpha”. “Alpha” provides the direction of the&#xA;  speed vector in a reference system tied to the aircraft and Pt-Ps&#xA;  provides the modulus of this vector. The three aerodynamic parameters&#xA;  therefore make it is possible to determine the speed vector of an&#xA;  airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These are covered by a &lt;a href=&quot;http://www.google.com/patents/US6490510&quot; rel=&quot;nofollow noreferrer&quot;&gt;US Patent&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Someone asked a similar question &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/333979/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="23223" LastEditDate="2019-08-28T14:25:59.627" LastActivityDate="2019-08-28T14:25:59.627" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="8204" PostTypeId="2" ParentId="8188" CreationDate="2014-08-18T16:49:29.210" Score="22" Body="&lt;p&gt;&quot;It depends&quot;.  As others have mentioned, GPS is receive only.  In theory at least, when everything is operating normally.  In practice, &lt;em&gt;some&lt;/em&gt; GPS units can fail in a way that causes them to become an unintentional radiator of energy.  GPS signals are VERY weak, so it doesn't take much to jam them.  However, this should be an exceptionally rare event, and terribly unlikely to happen with integrated handheld devices.   My personal GPS unit failure experience:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was flying a light twin (Piper Twin Comanche) with a Garmin 430 WAAS onboard and an iPad with EFB/position tracking software.  All of a sudden both of them lost GPS signal.  Eventually through trial and error we found that turning off the onboard (certified) Garmin 430W restored the iPad, but not the other way around.  Upon landing we gave the airplane over to the maintenance crew who discovered that the antenna cable to the Garmin was damaged.  Apparently it uses an amplified antenna, which when the cable became damaged turned into an incidental transmitter and jammed the GPS signal around us!&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-08-18T16:49:29.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8205" PostTypeId="2" ParentId="8201" CreationDate="2014-08-18T17:04:54.943" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/xml/CFR-2011-title14-vol3-part137.xml#seqnum137.51&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Part 137&lt;/a&gt; regulates agricultural aircraft operations, with §137.51 discussing operation over congested areas, including:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The crop duster must operate “with maximum safety to persons and&#xA;  property on the surface” and the crop duster must have obtained prior&#xA;  written approval from the FAA and notice of the intended operation&#xA;  must be given to the public. Further, the crop duster must submit a&#xA;  plan to the FAA that considers the flight obstructions and plans for a&#xA;  possible emergency landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of utmost importance is the section regarding the flying of &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/restrict/&quot; rel=&quot;noreferrer&quot;&gt;restricted category civil aircraft&lt;/a&gt; such as agricultural aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol2/xml/CFR-2011-title14-vol2-part91.xml#seqnum91.313&quot; rel=&quot;noreferrer&quot;&gt;Sec. 91.313&lt;/a&gt; — Restricted category civil aircraft: Operating limitations.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may operate a restricted category civil aircraft— (1)&#xA;  For other than the special purpose for which it is certificated; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) In an operation other than one necessary to accomplish the work&#xA;  activity directly associated with that special purpose.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Except when operating in accordance with the terms and conditions&#xA;  of a certificate of waiver or special operating limitations issued by&#xA;  the Administrator, no person may operate a restricted category civil&#xA;  aircraft within the United States—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Over a densely populated area;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) In a congested airway; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Near a busy airport where passenger transport operations are&#xA;  conducted.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More information is available in &lt;a href=&quot;https://webcache.googleusercontent.com/search?q=cache:Lk76S-HToD4J:https://www.faa.gov/other_visit/aviation_industry/designees_delegations/designee_types/ame/media/Section%2520II.4.3%2520Aerial%2520Application%2520Operations.doc%20&amp;amp;cd=2&amp;amp;hl=en&amp;amp;ct=clnk&amp;amp;gl=in&quot; rel=&quot;noreferrer&quot;&gt;this FAA document&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="1696" LastEditDate="2014-12-12T17:53:14.800" LastActivityDate="2014-12-12T17:53:14.800" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8206" PostTypeId="2" ParentId="8197" CreationDate="2014-08-18T18:21:39.250" Score="3" Body="&lt;p&gt;The first thing you should consider (and rely on) is &lt;a href=&quot;http://www.aviationweather.gov/adds/metars/&quot; rel=&quot;nofollow&quot;&gt;METAR&lt;/a&gt;. If you want to understand METAR, read &lt;a href=&quot;http://www.wunderground.com/metarFAQ.asp&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA has a &lt;a href=&quot;https://www.faa.gov/pilots/safety/media/ga_weather_decision_making.pdf&quot; rel=&quot;nofollow&quot;&gt;document&lt;/a&gt; for this. If you still like to read more, FAA Safety published this &lt;a href=&quot;https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56400/FAA%20P-8740-30%20GoodWeatherBriefing%5Bhi-res%5D%20branded.pdf&quot; rel=&quot;nofollow&quot;&gt;PDF&lt;/a&gt; too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviationweather.gov/briefing&quot; rel=&quot;nofollow&quot;&gt;Aviation Weather Center&lt;/a&gt; is a government website, which focuses on weather briefings related to aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flying school (near my place) has a link on their website to this &lt;a href=&quot;http://www.saiawos3.com/OQN/index2.html&quot; rel=&quot;nofollow&quot;&gt;service&lt;/a&gt;. I like the visual aspect of &lt;a href=&quot;http://en.wikipedia.org/wiki/Automated_airport_weather_station#Automated_Weather_Observing_System_.28AWOS.29&quot; rel=&quot;nofollow&quot;&gt;AWOS&lt;/a&gt; on this. They do not provide this service for all airports, but only for a &lt;a href=&quot;http://www.saiawos.com/onlinelist.php&quot; rel=&quot;nofollow&quot;&gt;handful&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a student, if you think weather is not good for flying, trust your gut and do not fly. No one would argue with you that any briefing says otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UPDATE:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA has a &lt;a href=&quot;http://www.aopa.org/wx/&quot; rel=&quot;nofollow&quot;&gt;service&lt;/a&gt; too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several apps which might be useful (e.g. &lt;a href=&quot;https://www.foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;ForeFlight&lt;/a&gt;, or &lt;a href=&quot;http://ipadpilotnews.com/2013/01/top-10-weather-apps-for-pilots/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; or &lt;a href=&quot;http://www.aopa.org/Flight-Planning/FlyQ/FlyQ-Pocket&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;). I have not tried any. In an AOPA weather seminar, they mentioned that those apps &lt;em&gt;do not&lt;/em&gt; present real time data but lag several minutes behind.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-08-18T18:42:00.320" LastActivityDate="2014-08-18T18:42:00.320" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8207" PostTypeId="1" CreationDate="2014-08-18T19:43:53.453" Score="8" ViewCount="2141" Body="&lt;p&gt;At what distance would you begin to see the sequenced flashing strobe on an approach light system at night? 10 NM? 20 NM? Visibility plays a role, but consider &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Aviation_CAVU&quot; rel=&quot;nofollow&quot;&gt;CAVU&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, strobe lights on radio and cell towers, what is their visibility distance at night?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And at those distances, are they initially faint as they fade into view?&lt;/p&gt;&#xA;" OwnerUserId="3238" LastEditorUserId="65" LastEditDate="2015-03-20T20:32:25.817" LastActivityDate="2015-03-20T20:32:25.817" Title="From how far strobe lights are visible?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8208" PostTypeId="2" ParentId="8207" CreationDate="2014-08-18T21:06:32.693" Score="5" Body="&lt;p&gt;For cell towers the FAA wants them to be visible for pilots in time for them to avoid them.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots of aircraft travelling at 165 knots (190 mph/306kph) or less&#xA;  should be able to see obstruction lights in sufficient time to avoid&#xA;  the structure by at least 2,000 feet (610m) horizontally under all&#xA;  conditions of operation, provided the pilot is operating in accordance&#xA;  with FAR Part 91. Pilots operating between 165 knots (190 mph/303&#xA;  km/h) and 250 knots (288 mph/463 kph) should be able to see the&#xA;  obstruction lights unless the weather deteriorates to 3 statute miles&#xA;  (4.8 kilometers) visibility at night, during which time period 2,000&#xA;  candelas would be required to see the lights at 1.2 statute miles&#xA;  (1.9km). A higher intensity, with 3 statute miles (4.8 kilometers)&#xA;  visibility at night, could generate a residential annoyance factor. In&#xA;  addition, aircraft in these speed ranges can normally be expected to&#xA;  operate under instrument flight rules (IFR) at night when the&#xA;  visibility is 1 statute mile (1.6 kilometers).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2070%207460-1K.pdf&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2070%207460-1K.pdf&lt;/a&gt; (page 63)&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-08-18T21:06:32.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8211" PostTypeId="2" ParentId="8188" CreationDate="2014-08-19T01:28:58.813" Score="2" Body="&lt;p&gt;Cellphones can affect airplane navigation equipment when not in airplane mode.  This was shown in &lt;a href=&quot;http://en.wikipedia.org/wiki/MythBusters_(2006_season)#Cell_Phones_on_a_Plane&quot; rel=&quot;nofollow&quot;&gt;a 2006 episode of Myth Busters&lt;/a&gt;.  In the link, please read the paragraph, this is true even though it says &quot;Busted&quot; on that page. This test was done in reasonably scientific manner and it shows that navigation equipment can be affected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More recently however &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?cid=TW189&amp;amp;newsId=15254&quot; rel=&quot;nofollow&quot;&gt;PED (Portable Electronic Devices) were deemed safe by the FAA for use during flight&lt;/a&gt;.  This includes cellular phones, with the expectation is that phones will be set to airplane mode.  Many devices, including the iPhone and iPad, with GPS functionality are included on this safe list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS, for your cellphone is for the most part a receive only activity.  Your cellphone does not have the power to transmit signals the 22,000+ miles it would need to get to a geostationary satellite in space.  Nor does it need to.  You can read &lt;a href=&quot;http://electronics.howstuffworks.com/gadgets/travel/gps.htm&quot; rel=&quot;nofollow&quot;&gt;how GPS works here&lt;/a&gt;.  Any electromagnetic device turned on will transmit some interference, but there isn't much reason to believe that your phone would add much more interference running with GPS on, versus while it's off.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interference coming from your GPS antenna should be coming from the frequency 1575.42 Mhz.  This range isn't mentioned on the &lt;a href=&quot;https://www.apple.com/legal/rfexposure/iphone5,1/en/&quot; rel=&quot;nofollow&quot;&gt;RF exposure information offered by Apple&lt;/a&gt; describing it's iPhones, presumedly because it is negligible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's reasonable to believe that having a GPS enabled phone should have negligible impact on a plane's navigation system.&lt;/p&gt;&#xA;" OwnerUserId="3245" LastEditorUserId="-1" LastEditDate="2014-08-19T10:24:08.917" LastActivityDate="2014-08-19T10:24:08.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8212" PostTypeId="2" ParentId="8188" CreationDate="2014-08-19T03:28:12.337" Score="9" Body="&lt;p&gt;The regulations on a plane used to forbid the use of any devices capable of sending radio signals - whether deliberately, or accidentally. Most radio receivers contain several &quot;intermediate frequency&quot; stages, where the incoming frequency is mixed with a &quot;local oscillator&quot; to produce lower frequencies which are easier on the electronics. These local oscillator frequencies have a tendency to &quot;escape&quot; from the receiver - but on GPS in particular, the amount of signal thus emitted is very small, and the frequencies are &quot;mostly harmless&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very helpful site on this topic is &lt;a href=&quot;http://gpsinformation.net/airgps/gpsrfi.htm&quot;&gt;http://gpsinformation.net/airgps/gpsrfi.htm&lt;/a&gt; . The most important sentence (IMO) from this site is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The interference potential of handheld GPS receivers is minimal.  However,  no passenger should EVER operate a GPS receiver on board an aircraft except in strict accord with the directives of the flight crew. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also has an extract of FAA regulation 91.21 . I found the original at the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=77005eeded2df0bbdf733e2390fee22a&amp;amp;node=se14.2.91_121&amp;amp;rgn=div8&quot;&gt;ecfr website&lt;/a&gt; (I added some emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.21   Portable electronic devices. &lt;br&gt;(a) Except as provided in&#xA;  paragraph (b) of this section, &lt;strong&gt;no person may operate&lt;/strong&gt;, nor may any&#xA;  operator or pilot in command of an aircraft allow the operation of,&#xA;  &lt;strong&gt;any portable electronic device&lt;/strong&gt; on any of the following U.S.-registered&#xA;  civil aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Aircraft operated by a holder of an air carrier operating&#xA;  certificate or an operating certificate; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Any other aircraft while it is operated under IFR.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Paragraph (a) of this section &lt;strong&gt;does not apply to&lt;/strong&gt;—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Portable voice recorders;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Hearing aids;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Heart pacemakers;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Electric shavers; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) &lt;strong&gt;Any other portable electronic device that the operator of the&#xA;  aircraft has determined will not cause interference&lt;/strong&gt; with the&#xA;  navigation or communication system of the aircraft on which it is to&#xA;  be used.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) In the case of an aircraft operated by a holder of an air carrier&#xA;  operating certificate or an operating certificate, the determination&#xA;  required by paragraph (b)(5) of this section shall be made by that&#xA;  operator of the aircraft on which the particular device is to be used.&#xA;  In the case of other aircraft, the determination may be made by the&#xA;  pilot in command or other operator of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notice - the FAA basically &lt;strong&gt;does not have the final say&lt;/strong&gt; - they say &quot;if the operator determines it is safe, then go ahead&quot;. Conversely, if the carrier doesn't say it's safe, you are actually breaking the law by doing this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you will need to check with the operator of the flight. For example, Delta &lt;a href=&quot;http://www.delta.com/content/www/en_US/support/faqs/during-your-trip/personal-electronic-devices.html&quot;&gt;explicitly allows the use of portable GPS&lt;/a&gt; from gate to gate:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You may use the following devices from gate to gate on Delta and Delta Connection flights:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;AM/FM or satellite radios&lt;/li&gt;&#xA;  &lt;li&gt;digital and video cameras&lt;/li&gt;&#xA;  &lt;li&gt;calculators&lt;/li&gt;&#xA;  &lt;li&gt;Delta-installed equipment such as in-flight entertainment systems&lt;/li&gt;&#xA;  &lt;li&gt;DVD players*&lt;/li&gt;&#xA;  &lt;li&gt;e-readers&lt;/li&gt;&#xA;  &lt;li&gt;electric shavers&lt;/li&gt;&#xA;  &lt;li&gt;electronic/digital watches&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;global positioning system (GPS) receivers&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;handheld computer games&lt;/li&gt;&#xA;  &lt;li&gt;headphones&lt;/li&gt;&#xA;  &lt;li&gt;laptop computers*&lt;/li&gt;&#xA;  &lt;li&gt;medical devices**&lt;/li&gt;&#xA;  &lt;li&gt;noise reduction headphones&lt;/li&gt;&#xA;  &lt;li&gt;portable media players*&lt;/li&gt;&#xA;  &lt;li&gt;pagers&lt;/li&gt;&#xA;  &lt;li&gt;smartphones and any device with cellular network service must be turned off or in airplane mode&lt;/li&gt;&#xA;  &lt;li&gt;tablets and wireless keyboards or mouse&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I was surprised to see wireless keyboards in this list. These are devices that are designed to transmit radio signals - admittedly Bluetooth is low power, but it shows that airlines have actually gone from a blanket &quot;no way&quot; to doing the measurements needed to prove that these things are safe. Either that, or they are reckless in an attempt to attract customers. Let's hope it's the former...&lt;/p&gt;&#xA;" OwnerUserId="3052" LastEditorUserId="3052" LastEditDate="2014-08-19T12:45:58.787" LastActivityDate="2014-08-19T12:45:58.787" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8213" PostTypeId="2" ParentId="8188" CreationDate="2014-08-19T03:56:34.993" Score="-1" Body="&lt;p&gt;I would have added a comment to @JamesHam's answer but I don't have the rep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long story short, Your GPS on your phone is receive only. Yes your antenna will generate some field but I doubt it is much stronger when the phone is on than when it off. (However, antenna and interference were not my area of expertise.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS signals travel at the speed of light. Even plane at top speed is still very close to stationary by comparison to the speed of light. Any issues you have with regards to GPS at speed have to do with your phone's hardware/software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the safety issue is concerned... It is a myth. Period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this is not my area of expertise a little simple logic goes a long way. Consider that your plane is awash in signals at a lot of frequencies while it is on the ground and at landing and takeoff (the most dangerous times). Signals from cell towers, FM and AM radio stations, GPS, DirecTv, lightning, etc. All of these sources bathe the airplane in EM waves across a slew of frequencies. Most bathe airplane with much more power than your phone can. Additionally, every wire with electricity in the airplane puts out an EM signal as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another logic argument, there are approx 200+ people on every major flight in the US. If only 1% forget to turn off our phone that means there are at least 2 people on every flight with their phone's on the entire flight. EM interference happens over the course of less than a second so every hr of flight time represents at least 3600 discrete opportunities for EM interference per operational phone. How many flights crash every day?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any modern aircraft is digital not analog. So interference due to EM can really only cause a flipped bit or a few. As far as a sweet spot in frequencies is concerned the most likely culprit for interference will come from other aircraft systems that sample and process data at the same frequency as the system being interfered with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But so what? Every sensor man has ever created will create the occasional bad data point. Planes, satellites, etc all have to be robust to a few bad data points. So every computer that consumes sensor data on airplane has filters built in to it specifically to deal with a short series of bad data points.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically the navigation system is usually blamed when the FAA or someone says EM interference brought that plane down. They then go about telling you how impossible it would be to prove it. So ... why do we believe them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navigation system in particular is built in such a way as to cope with missing and bad data. Typically the nav system uses some combination of multiple attitude, acceleration, velocity, and position sensors operating at different update frequencies. GPS is often only updated once a second while gyros and accelerators are updated sometimes 1000s of times a second. Then there is a propagator (or estimator) that calculates the aircraft's position, velocity, and attitude in between GPS updates using the faster sensor data. All of that sensor data is filtered so that the occasional garbage data point (which every sensor ever built generates) doesn't cause the aircraft to behave wildly, unpredictably, and sometimes fatally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nav system is often blamed because it is all software and sensors. The engine can't spin up or slow down fast enough for a few spurious data points to cause issues. Neither could the controls surfaces (flaps, ailerons, etc). A spurious blip in the radio or radar by themselves doesn't cause an aircraft to go down. So by deduction it can only be the nav system becoming confused by bad data. Except every modern nav system is inherently robust to noise on the sensor data and the larger the error is in the spurious noisy data the easier it gets filtered out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oh, and every single computer system on an aircraft is shielded against EM interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EM interference is a boogey man the FAA uses when they don't have an answer. It is reproduce-able in a lab in just the right setting. But the aircraft would never have gotten off the ground if it were sensitive enough to crash due to your cell phone or even 200 cell phones simultaneously in use on board.&lt;/p&gt;&#xA;" OwnerUserId="3241" LastActivityDate="2014-08-19T03:56:34.993" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="8214" PostTypeId="1" AcceptedAnswerId="8239" CreationDate="2014-08-19T07:14:15.163" Score="1" ViewCount="6981" Body="&lt;p&gt;I want to be a pilot (civil aviation), but I'm afraid that my body composition and field of study might not fit with aviation. What are the physical requirements and academic/mental prerequisites to become a private pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, I have a masters degree in computer engineering and am skinny (50Kg, 1.72m and 24age). Could this be a problem?&lt;/p&gt;&#xA;" OwnerUserId="3247" LastEditorUserId="2984" LastEditDate="2014-08-19T14:22:44.937" LastActivityDate="2016-03-09T15:46:09.720" Title="What physical and mental attributes do I need to become a pilot?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8215" PostTypeId="2" ParentId="8214" CreationDate="2014-08-19T07:54:46.607" Score="1" Body="&lt;p&gt;There's no prohibition on computer engineers being pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So long as you can operate the controls of your aircraft and see out clearly, there's no reason why height, weight or age should be an obstacle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.dailymail.co.uk/femail/article-2231780/Rachael-Spelling-youngest-Britain-fly-aeroplane-solo-flying-16th-birthday.html&quot; rel=&quot;nofollow&quot;&gt;16 year-old schoolgirl can be a pilot&lt;/a&gt;. &#xA;and &lt;a href=&quot;http://en.wikipedia.org/wiki/Jessica_Dubroff&quot; rel=&quot;nofollow&quot;&gt;trainees are as young as 7&lt;/a&gt;. In some places &lt;a href=&quot;http://www.mirror.co.uk/news/weird-news/child-aged-five-worlds-youngest-2245038&quot; rel=&quot;nofollow&quot;&gt;at age 5, you can be a pilot&lt;/a&gt; of sorts. It's a bit harder to get a job flying jumbo jets commercially, but there are &lt;a href=&quot;http://metro.co.uk/2012/06/27/jumbo-jet-pilot-is-one-of-the-worlds-youngest-at-just-20-years-old-483000/&quot; rel=&quot;nofollow&quot;&gt;20-year olds doing this&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you have to put in the time and effort and have a minimum of&#xA;health and mental competence.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-19T08:06:40.260" LastActivityDate="2014-08-19T08:06:40.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8216" PostTypeId="2" ParentId="8214" CreationDate="2014-08-19T08:33:49.890" Score="1" Body="&lt;p&gt;Based on the vital statistics related to your physique that you have provided you can very easily apply for a Pilot's licence . Some of the important information related to how one can become a Pilot are as follows :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) You do not need to go to an Aviation College and get an Aviation degree to become a pilot. Some regional US airlines prefer an associates degree or at least two years of college experience. Major airlines typically require a bachelors degree, but it can be in any field of study, not just aviation .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2)As long as your vision can be corrected to 20/20 with glasses or contacts, you will be eligible for a 1st Class FAA Medical Certificate, which makes you eligible to fly as a civilian professional pilot .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) The cost of flight school is relatively expensive and most students will need to finance some, if not all, of the flight training cost . Airlines will perform a credit check as a standard step in their background check process .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(4) You can hold a commercial pilot certificate as young as 18 years old .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The detailed information can be found here&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airaffair.com/Library/start-airplanes.html&quot; rel=&quot;nofollow&quot;&gt;http://www.airaffair.com/Library/start-airplanes.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For a Synopsis of Medical Standards prescribed by FAA , you may choose to visit this site&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2014-08-19T08:42:50.280" LastActivityDate="2014-08-19T08:42:50.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8219" PostTypeId="1" CreationDate="2014-08-19T09:23:35.240" Score="6" ViewCount="4273" Body="&lt;p&gt;I am trying to understand the competitive positions of Airbus and Boeing's large civil aircrafts. I would imagine fuel efficiency would be very important to airline given its large component in the total costs of operating. Where can I get information on the fuel efficiency of the large major planes e.g. A320 vs 737 etc?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you&lt;/p&gt;&#xA;" OwnerUserId="3252" LastActivityDate="2017-11-03T13:17:48.517" Title="Where can I find accurate information about fuel efficiency of Airbus vs. Boeing planes?" Tags="&lt;fuel&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8221" PostTypeId="2" ParentId="8219" CreationDate="2014-08-19T11:12:18.160" Score="6" Body="&lt;p&gt;Fuel consumption is a very important issue, and much besides the airplane or engine manufacturer influences the final result. Both Airbus and Boeing publish only marketing numbers, and require a non-disclosure agreement before they reveal any meaningful figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approximately three quarters of the progress in fuel consumption in the last fifty years has been achieved with better engines, and the airframe and better operational procedures contributed only the remaining quarter. If there is any difference between contemporary Airbus and Boeing planes, it is very small, and any advantage is usually reversed with the next upgrade or new model from either company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/7971/atlantic-fuel-burn-estimations&quot;&gt;Atlantic fuel burn estimations&lt;/a&gt;. It has links to tools for fuel burn calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a first approximation, use 55 to 65 g of fuel per Newton-hour or 15 to 18 g per kN of thrust per second with modern jet engines. Please do not use the static thrust at sea level, but the actual thrust at the right flight Mach number and altitude. If you lack this figure: A modern airliner needs thrust equivalent to between 1/18th (5.6%) and 1/12th (8.3%) of its weight. In cruise flight at Mach 0.82 the higher number of 8.3% should be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things which have an influence on fuel consumption:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight speed. Usually flying a little slower helps, but normal operations are already quite close to the optimum. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/3748/why-1st-and-2nd-class-but-not-fast-or-slow-airplanes&quot;&gt;here&lt;/a&gt; for a related question.&lt;/li&gt;&#xA;&lt;li&gt;Flight altitude. Flying as high as thrust allows helps, but is not always possible. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;here&lt;/a&gt; for a related question.&lt;/li&gt;&#xA;&lt;li&gt;Operating mass. Lighter aircraft can fly higher and have less drag. Excessive reserve fuel rules cause fuel burn to go up.&lt;/li&gt;&#xA;&lt;li&gt;Flight path. Usually the direct route is best, but sometimes gains can be made by avoiding a headwind en route.&lt;/li&gt;&#xA;&lt;li&gt;Proper piloting. Flying with a small amount of sideslip already destroys any advantage winglets might have, and drag goes up quickly with sideslip. This is mostly an issue for propeller airplanes, though.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance status of the engines. Engines lose a few percent of efficiency over their operating life.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance status of the airframe. Dirty wings or badly fitting doors produce more drag, and condensed water in the belly adds some additional weight which increases fuel burn. Condensed moisture can accumulate in the fuselage, and airliners in Africa can well have a few tons of condensed water onboard.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is why in real life the fuel burn varies, so any published figures out of context are hard to verify.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="65" LastEditDate="2017-11-03T13:17:48.517" LastActivityDate="2017-11-03T13:17:48.517" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8222" PostTypeId="2" ParentId="8219" CreationDate="2014-08-19T11:19:12.387" Score="1" Body="&lt;p&gt;For this you will need the Fuel Capacity, Range and Pax capacity data .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get the Fuel Capacity, Range and Pax capacity data from the  homepages of Airbus A320 and Boeing 737 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airbus A320&lt;/strong&gt; :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a320family/a320/specifications/&quot; rel=&quot;nofollow&quot;&gt;http://www.airbus.com/aircraftfamilies/passengeraircraft/a320family/a320/specifications/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Boeing 737&lt;/strong&gt; :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/boeing/commercial/737family/pf/pf_800tech.page&quot; rel=&quot;nofollow&quot;&gt;http://www.boeing.com/boeing/commercial/737family/pf/pf_800tech.page&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you get those figures divide the fuel capacity by range and then further divide that by the pax capacity .&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-19T11:19:12.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8225" PostTypeId="2" ParentId="8188" CreationDate="2014-08-19T14:06:23.357" Score="6" Body="&lt;p&gt;Generally GPS is a receive only service and does not transmit. Because of this it is considered safe to use in aircraft as long as the use of electronic devices in general is permitted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, from your question it seemed that the whole topic came up because the iPhone turns off the GPS when turning on flight mode. You concluded &quot;it means that at least a few people at Apple are worried about people using GPS in flight.&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am sure this is an incorrect conclusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason the GPS is turned off on an iPhone when you turn on flight mode is that the GPS and radio are handled by the same chip in some of the iPhones models and that both services are intrinsically linked on iOS devices. This is not the case for some other smart phones. Specifically:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GSM iPhone 4 still used the Broadcom BCM4750 which could be turned on separately from the radio, but the CDMA version uses the Qualcomm MDM6600 which has Radio and GPS in one chip and is not discretely powered. The iPhone 4S uses the Qualcomm MDM6610 chip for both. I have not researched the 5 or 5S. For Apple its simply easier to turn off all the stuff on all devices rather than throw in multiple options for multiple devices. On top of that Apple uses assisted GPS (AGPS) which downloads satellite coordinates over the network and reduces the time to get a GPS fix from minutes to a few seconds. This is another reason for apple to turn off both together rather than cripple GPS performance without network.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this clarifies things.&lt;/p&gt;&#xA;" OwnerUserId="3251" LastActivityDate="2014-08-19T14:06:23.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8226" PostTypeId="1" AcceptedAnswerId="8228" CreationDate="2014-08-19T14:56:19.237" Score="16" ViewCount="4792" Body="&lt;p&gt;I'm planning a Labor Day flight to a relative's house, and the nearest airport is a Private Airport that looks to be part of a flying community (multiple houses all with hangars directly off the small runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no experience with private airports.&lt;br&gt;&#xA;If I ask nicely in advance, am I likely to get permission to use it?&lt;br&gt;&#xA;Or are they likely to be protective of their privacy and airport?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize any answer can't apply in all circumstances, but I'm asking if its worth a phone call and conversation? or if I should just go directly to the nearest public airport?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="609" LastEditDate="2015-04-09T14:47:53.283" LastActivityDate="2016-11-14T12:37:31.937" Title="Am I likely to get permission at a Private Airport?" Tags="&lt;airport&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8228" PostTypeId="2" ParentId="8226" CreationDate="2014-08-19T15:57:58.293" Score="19" Body="&lt;h2&gt;Can't hurt to ask!&lt;/h2&gt;&#xA;&lt;p&gt;I don't know the specifics of the situation, but I would be willing to bet that your chances are better than you think.  If it was one farmer with a grass strip and no accommodations for visiting aircraft you might be out of luck, but from what you describe it doesn't sound like one extra airplane on the ground for a few hours is going to make that much of a difference.&lt;/p&gt;&#xA;&lt;p&gt;In fact, it might be that Fred (or whoever) will also be visiting friends for Labor Day and might be willing to let you use his ramp.&lt;/p&gt;&#xA;&lt;p&gt;They can't say yes if you don't ask.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-19T15:57:58.293" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8229" PostTypeId="2" ParentId="8226" CreationDate="2014-08-19T16:12:36.670" Score="15" Body="&lt;p&gt;Probably &lt;strong&gt;yes&lt;/strong&gt;, if you follow their rules and pay the fee.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the description you wrote, it appears to be similar to &lt;a href=&quot;http://en.wikipedia.org/wiki/Lakeway_Airpark&quot; rel=&quot;noreferrer&quot;&gt;Lakeway Airport&lt;/a&gt;. Here is a picture of the runway which has houses next to it and have hangars built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jnHkD.jpg&quot; alt=&quot;Airpark homes at Lakeway Airport&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On their &lt;a href=&quot;http://www.3r9.org/&quot; rel=&quot;noreferrer&quot;&gt;website&lt;/a&gt;, they did mention that it is a private airport but if you want to land there, there are some rules and fees which apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to my little knowledge, you should always contact an unfamiliar airport first to get all the necessary information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good Luck!&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-08-20T13:51:47.413" LastActivityDate="2014-08-20T13:51:47.413" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8230" PostTypeId="2" ParentId="8214" CreationDate="2014-08-19T16:18:32.020" Score="1" Body="&lt;p&gt;You definitely are big enough.  My daughter did her first flying lesson at 11 or so.  We had to pull the seat way up and have her sit on a cushion.  She was well under 5 feet and 100 pounds at the time.  She did just fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the academic/mental prerequisites a calm demeanor is good. As is thinking ahead, plan, not react. Just remember the most important thing is the next two things.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other thing to remember is the plane does not care what degrees you had, what university you went to, etc.  So don't think that since you have a graduate degree you have a leg up on someone that is a high school drop out.  I have had this reinforced to me several times.  I have several degrees (physics, math, computer science) and all of that learning meant zero if I don't practice the basic over and over and exercise good airmanship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best of luck with your flight training, and have fun.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-08-19T16:18:32.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8231" PostTypeId="2" ParentId="8197" CreationDate="2014-08-19T16:32:41.560" Score="6" Body="&lt;p&gt;At least in the US there are plenty of ways to get a flight briefing.&lt;br&gt;&#xA;My usual sources of pre-flight information are, roughly in order:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.weather.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Weather Channel&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;No kidding, if I'm planning a long/multi-day trip I'll start looking at the long-range forecasts 10 days before my flight using The Weather Channel's iPhone app or their website.&lt;br&gt;&#xA;As far as weather information goes it's pretty decent (which means &quot;frequently wrong up until 24 hours before go-time, but still worth paying attention to&quot;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Charts (&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR&lt;/a&gt; or &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/ifr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;IFR&lt;/a&gt;), &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport Diagrams&lt;/a&gt;, and &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A/FD&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;If you're planning more than a hop around the local pattern you should familiarize yourself with the airspace you'll be passing through, landmarks (and obstacles) on the ground, and navaid / airport frequencies. Charts and other FAA publications provide a great way to do that, and you can also usually pick up a phone and call the airport you're flying to for additional information.&lt;br&gt;&#xA;All of this documentation is available in a variety of forms - Paper, electronic downloads direct from the FAA (as linked above), or as part of flight-planning software like Foreflight, Garmin Pilot, WingX Pro, etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://weather.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;The National Weather Service&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;A few days before a planned flight it's worth reading the forecaster's discussion to see how confident the people predicting the weather are about their guesses. This is also something you should check the day of departure if there's any uncertainty about the weather.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Electronic briefing tools&lt;/strong&gt; (&lt;a href=&quot;https://www.duat.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;DUAT&lt;/a&gt;/&lt;a href=&quot;http://duats.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;DUATS&lt;/a&gt;/Foreflight/etc.)&lt;br&gt;&#xA;About 24 hours out you can get official briefings from DUAT/DUATS/Foreflight and a bunch of other flight planning tools. Get them and learn to read them.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Electronic briefings from many of these tools are recorded and count as an &quot;official briefing&quot; - a record is made that you requested and received the information. You are responsible for understanding all the information that just got dumped in your lap however, and that's a &lt;strong&gt;huge&lt;/strong&gt; responsibility, especially for a student pilot!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.afss.com/index.cfm?regid=%23.%40%2C.%0A&amp;amp;fwnavid=%23.P%2C)%0A&amp;amp;navMode=(%3FT%3D%3A(Y%3EJ%3B1%5C%20%0A/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Service Briefings&lt;/a&gt;&lt;/strong&gt; (1-800-WX-BRIEF)&lt;br&gt;&#xA;The day of departure your final briefing should be a phone call to flight service to speak with an actual briefer to review your flight. If you can sit down and have your electronic briefing from #3 in front of you it's very helpful because you can follow along with the briefer to be sure you didn't miss anything.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Calls to Flight Service are recorded and count as an official briefing. If you're unclear on anything you're being told you can ask for clarification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of all the tools available I personally think the best one is calling flight service and speaking to a briefer. &lt;a href=&quot;https://aviation.stackexchange.com/questions/8197/what-are-the-best-practices-for-gathering-preflight-weather-and-information/8206?noredirect=1#comment14390_8206&quot;&gt;If your instructor has never made you do this&lt;/a&gt; I'd say they're skipping out on a critical bit of your training, and you owe it to yourself to pick up the phone and .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is your big chance to talk to a live human being and ask any questions - big ones that I &lt;em&gt;always&lt;/em&gt; ask are &quot;Are there any TFRs along my route of flight?&quot;, and if I'm anywhere near a restricted area I'll check its status (&quot;Is R-12345 active?&quot;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-08-19T19:11:24.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8232" PostTypeId="2" ParentId="8207" CreationDate="2014-08-19T17:39:24.947" Score="3" Body="&lt;p&gt;Flying through Central Valley of California at night I have seen runway light from many miles away.  Probably 20nm+.  The valley is low and flat with with a lot of airport in low population areas.  As a result the runway lights in general, and approach lights in particular really stand out.  Conversely when you are in a highly populated area (ex. Southern California) while the light travels as far, but you may have trouble picking up the runway environment out of the sea of lights.  So having slant visibility does not necessarily equate to &quot;seeing&quot; the airport.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-08-19T17:39:24.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8233" PostTypeId="1" AcceptedAnswerId="8234" CreationDate="2014-08-19T18:16:11.380" Score="7" ViewCount="9004" Body="&lt;p&gt;If you look at the &lt;a href=&quot;http://www.noaa.gov/&quot;&gt;National Oceanic and Atmospheric Administration's (NOAA)&lt;/a&gt; &lt;a href=&quot;http://www.weather.gov/&quot;&gt;National Weather Service (NWS)&lt;/a&gt; page for &lt;a href=&quot;http://w1.weather.gov/obhistory/KDCA.html&quot;&gt;Washington D.C., Reagan National Airport (KDCA)&lt;/a&gt;, it shows hourly weather observations proceeding back from present through time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I notice that there has been 10.00 miles visibility all the way back to 17 August, where for one hour there was only 7 miles visibility. During these hours of 10 mi visibility, there are multiple conditions of cloud cover, ranging from Light Clouds, to Overcast, to Light Rain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is &quot;visibility&quot; when added to a weather report broadcast from an airport? It seems that if I am in the middle of Light Rains, well then my visibility cannot be &quot;10 miles&quot;.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="1696" LastEditDate="2016-07-05T19:23:51.180" LastActivityDate="2016-07-05T19:23:51.180" Title="What is the definition of visibility as seen in aviation weather reports?" Tags="&lt;weather&gt;&lt;visibility&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8234" PostTypeId="2" ParentId="8233" CreationDate="2014-08-19T18:38:02.037" Score="8" Body="&lt;p&gt;All my quotes for this post comes from FAA Order &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/JO%207900.5C.pdf&quot;&gt;7900.5C&lt;/a&gt;, the Surface Weather Observing Guide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Visibility is defined as &quot;Visibility is a measure of the horizontal opacity of the atmosphere at the point of observation and is expressed in terms of the horizontal distance at which a person should be able to see and identify specific objects.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All METARs report Prevailing Visibility, which is: &quot;Prevailing visibility is the greatest visibility equaled or exceeded throughout at least half the horizon circle, which does not necessarily have to be continuous. This is the visibility that is considered representative of visibility conditions at the station.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automated stations, generally report a max visibility of 10 SM. Now if you look at stations that are completely manual, i.e. KBJC(when I worked there it was a completely manual station), we'd report anywhere up to 70SM or higher visibility, due to our visibility markers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-RA can often be easily seen through, RA or RA+ do become harder to see through, and as always, it can be dependant on where the -RA is, if it's only in a tiny quadrant of the horizon circle, it can often be a greater visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Edit Post comment about RA]: Sorry, used a few more abbreviations. SM = Statute Miles, which is like a regular mile that most people use in their daily lives. It's depicted as SM, due to most other things in aviation being in Nautical Miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-RA, RA, +RA, are the various descriptors for Rain. -RA means light rain, which if just using vis concerns is defined as, &quot;From scattered drops that, regardless of duration, do not completely wet an exposed surface up to a condition where individual drops are easily seen.&quot; RA, is Moderate Rain, defined as: &quot;Individual drops are not clearly identifiable; spray is observable just above pavements and other hard surfaces&quot; and +RA is heavy Rain, &quot;Rain seemingly falls in sheets; individual drops are not identifiable; heavy spray to height of several inches is observed over hard surfaces.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, METAR is the type of aviation weather report. METAR's are the hourly/standard report, and then there's SPECI's which if certain changes occur in conditions, from Freezing Rain, to changes in visibility or cloud ceilings, to massive wind shifts, to thunderstorms, to other factors, can be produced outside of the hourly/regular report.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="2785" LastEditDate="2014-08-19T19:07:10.867" LastActivityDate="2014-08-19T19:07:10.867" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8235" PostTypeId="2" ParentId="8233" CreationDate="2014-08-19T18:55:22.203" Score="2" Body="&lt;p&gt;There is a &lt;a href=&quot;http://www.nws.noaa.gov/asos/vsby.htm&quot; rel=&quot;nofollow&quot;&gt;good explanation&lt;/a&gt; from the National Weather Service about visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weather observation system measures the clarity of the air. This is done by measuring the amount of light scattered from a light source, such as a Xenon flash lamp, across a distance of 0.75 feet. This is measured every 30 seconds, and each minute is averaged over the past 10 minutes to produce the reported value. Although this is adjusted to allow for changing conditions, there will be some lag before the average reflects new conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This system can differ from human vision for various reasons, and reflected light from precipitation is one possibility. Bright conditions will also cause the system to over-report visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The perspective of surface observers will also be different from the view pilots have higher up.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-08-19T18:55:22.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8238" PostTypeId="2" ParentId="8214" CreationDate="2014-08-19T22:32:07.877" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the physical requirements &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My (future) mother-in-law saw me stepping out of the airplane and said to her daughter &quot;how can such a little guy fly such a big airplane*?&quot; In a word, &lt;em&gt;hydraulics&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately you must be able to move the control surfaces through their normal range of motion, perform emergency procedures, and safely control the aircraft. There is no rule that says you're not allowed to slide down the seat a couple inches to get full rudder deflection because your left engine just quit. I personally know a pilot who flew with a very thick book behind his back. No, I'm not kidding.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;99' 6'' long, 130' wingspan, 156,000 lbs max GW &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1798" LastEditorUserId="1798" LastEditDate="2014-08-19T22:40:22.400" LastActivityDate="2014-08-19T22:40:22.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8239" PostTypeId="2" ParentId="8214" CreationDate="2014-08-20T02:09:57.877" Score="5" Body="&lt;p&gt;Shhhhhh, here is the biggest secret of aviation: It's actually quite easy to become a pilot.  You can actually get your private certificate before you are allowed to drive!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/pilots/become/&quot; rel=&quot;nofollow&quot;&gt;The FAA has a nice page that tells you what is required to become a private pilot&lt;/a&gt;.  When most people think of piloting small general aviation aircraft, they are thinking about the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States#Private_pilot&quot; rel=&quot;nofollow&quot;&gt;Private Pilot&lt;/a&gt; certificate.  Part 141 is the most common route for that.  The hardest part is being able to pass the FAA physical, but keep in mind that as a private (or even recreational) pilot, you don't need to get a Class I, just a Class III.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To become an airline (ATP) or military pilot does require a great deal more work and training, but I think that may be beyond the scope of your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best advice is to go to the local airfield or FBO and find a flight school.  Good luck.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="504" LastEditDate="2014-08-23T09:43:31.553" LastActivityDate="2014-08-23T09:43:31.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8240" PostTypeId="2" ParentId="2752" CreationDate="2014-08-20T02:17:40.280" Score="4" Body="&lt;p&gt;Absolutely!  The same airspace restrictions that are in the US are regulated by the FAA and ICAO.  The FAA (or the US) is a signatory to the ICAO standards, and as part of that governing body instituted the same rules worldwide. Those restrictions are also issued through the NOTAM system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, flying in the UK, we had restrictions on where we could fly depending on where the Queen was flying (if our missions coincided with her flights).  They even had a rather unflattering name for those flights in the pilot community.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.telegraph.co.uk/news/uknews/queen-elizabeth-II/8694089/Queen-looking-for-80000-a-year-pilot.html&quot; rel=&quot;nofollow&quot;&gt;Here is an article that talks a little bit about th e roles and responsibilities of the Queen's pilots&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://notaminfo.com/node/5&quot; rel=&quot;nofollow&quot;&gt;You can also check UK NOTAMS&lt;/a&gt; (although i don't see any current ones fo rthe Queen at the moment).&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="3266" LastEditDate="2014-08-21T01:36:14.637" LastActivityDate="2014-08-21T01:36:14.637" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8242" PostTypeId="2" ParentId="8055" CreationDate="2014-08-20T02:48:59.220" Score="17" Body="&lt;p&gt;I have worked on and designed DIRCM systems.  Most of the technical specifications on these systems is classified.  Also, the U.S. is not the only country with DIRCM systems.  In particular, Israel is equipping their airliners with the &lt;a href=&quot;https://www.youtube.com/watch?v=uVlERTFVSpo&quot; rel=&quot;noreferrer&quot;&gt;C-MUSIC system&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How does this system work?&lt;/strong&gt;&#xA;Basically, a laser at the wavelengths of the Infrared Missile seeker is directed at the incoming missile.  It is pulsed in such a way as to cause the missile to think that the hot spot that it is tracking (generally the engines) is not in the right spot for proportional steering. Without proportional steering, the missile avionics thinks that the missile will miss the target, so it corrects for this.  As it corrects, the laser signal continues to misinform the missile as to where the target is in its reticle, eventually causing the missile to &quot;break lock&quot; and fly off into a random direction. Before the laser can be directed at the missile though, there are several other steps, which is why you have a complete pod.&#xA;First a missile warning system needs to pick up the fact that a missile has been launched at the aircraft (generally the job of a series of IR cameras that give a lower hemispheric view of the aircraft's environment). Then the system tells the turret to turn to a specific point in space. The turret has its own IR camera that is responsible for tracking the missile, and once it has achieved this tracking, only then does the laser start to fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Does this successfully work in countering all types of missiles?&lt;/strong&gt;&#xA;This is only effective against purely infrared guided missiles (mainly MANPADs and some varieties of air to air missiles, such as the AIM-9).  If the missile has any sort of radar assist, or is radar guided, a laser will do no good.  There are some classes of laser riding missiles that could potentially be confused by these type of systems, but no &lt;em&gt;anti-air&lt;/em&gt; types of laser guided missiles are deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many IR guided missiles do try to counter these countermeasures, so the more sophisticated DIRCM systems need to be employed. IR missiles come in many different varieties of seekers and wavelengths they use, so the DIRCM system needs to have a laser on those wavelengths.  Not only that (and this is where the secret sauce comes in) each seeker operates on different frequencies of their reticles (and reticle patterns). So to truly confuse a missile, one needs what is known as a Jam Code. These are generally classified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Can it be reused over multiple missile strike incidents?&lt;/strong&gt;&#xA;As long as the laser is operational, the system can be used over and over again.  Some lasers have limits to how long they can fire, and how often they can fire (the Northrop Viper laser is notoriously power limited and has a horrible MTBF).  However, as long as there is power, it doesn't run out of ammo.  This is the main advantage of DIRCM systems over using infrared countermeasures such as flares, which are limited by the number of flares one can carry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are all commercial airplanes compatible with this system?&lt;/strong&gt;&#xA;The Guardian, as well as BAE's JetEye, and Elbit's MUSIC system is designed as to be integrated onto any large airframe.  Israel has already flown it on 707 and 737 airframes, and plan to integrate it to the A-320, 747, 757, 767, and even some Embraer airfrmaes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is it economical for a major airline to fit all of its fleet with this system?&lt;/strong&gt; &#xA;Not really, unless one gets shot down by a MANPAD.  The DIRCM system will cost well over a million $US (probably closer to two).  And then there is the aerodynamic penalty of hauling a 350-500lbs pod on your belly.  The concept Elbit is employing is to install aircraft with a B-kit (an interface plate and the necessary wiring).  Then the airline can buy a limited number of A-kits, and install them only on the aircraft that are going to an area that may be dangerous. Notionally, this operation can be done in an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the danger, all I can say is that over 500,000 MANPADS have been manufactured, &lt;a href=&quot;http://nypost.com/2014/07/23/missiles-threaten-civilian-planes-all-over-the-world/&quot; rel=&quot;noreferrer&quot;&gt;and many thousands are in the hands of people that wouldn't mind causing a &quot;problem&quot; for anyone they can inconvenience&lt;/a&gt;. Thankfully, the training required is a bit more than firing an AK-47, so most attempts have been unsuccessful.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="4452" LastEditDate="2018-03-28T06:49:19.313" LastActivityDate="2018-03-28T06:49:19.313" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8243" PostTypeId="2" ParentId="2752" CreationDate="2014-08-20T06:44:57.210" Score="4" Body="&lt;p&gt;Yes, there is. I remember last time when US president was in Prague, LKPR was closed for quarter or half an hour around his arrival.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-08-20T06:44:57.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8244" PostTypeId="1" AcceptedAnswerId="8247" CreationDate="2014-08-20T10:22:23.423" Score="9" ViewCount="4118" Body="&lt;p&gt;I am trying to understand how much of a hassle and cost it would be for a large civil airline, who already had lots of installed Rolls Royce engines on its fleet, to switch over to GE engines on new planes they have ordered. For example if they opted for the RR Trent 1000 on a 787 initially but then changed new orders of 787's to have the GEnx-1B. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very intangible I know, but would it be fair to say that switching would require some difficulty including:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;retraining of pilots&lt;/li&gt;&#xA;&lt;li&gt;changing maintenance schedules&lt;/li&gt;&#xA;&lt;li&gt;additional uncertainty over performance and fuel efficiency&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Alternatively, I could be wrong, and the airline will likely just switch to the GE if it thinks it can gain a small fuel burn advantage, in which case RR's back book of engines does not mean clients will opt for the RR engine choice going forward.&lt;/p&gt;&#xA;" OwnerUserId="3252" LastEditorUserId="1467" LastEditDate="2015-04-17T08:59:50.900" LastActivityDate="2015-04-17T08:59:50.900" Title="How much would it cost for a large airline to switch engine manufacturer for their planes?" Tags="&lt;airline-operations&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8245" PostTypeId="1" AcceptedAnswerId="8246" CreationDate="2014-08-20T11:11:43.497" Score="8" ViewCount="273" Body="&lt;p&gt;Have any governmental agencies done comprehensive tests on the effects of personal electronic devices used in the cabins (and cockpits) of commercial airliners?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the ubiquitousness of cell phones, laptops, kindles, ipads, etc, it strikes me that &lt;em&gt;everyone&lt;/em&gt; seems to just &lt;strong&gt;know&lt;/strong&gt; that using a cell phone in the cabin of an airliner has no appreciable/measurable affect on the electronics of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="17780" LastEditDate="2017-01-25T14:47:57.973" LastActivityDate="2017-01-25T14:47:57.973" Title="Have objective and verified tests been done of the effects of personal electronic devices on a commercial airliner's operation?" Tags="&lt;airliner&gt;&lt;electronics&gt;&lt;cell-phone&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8246" PostTypeId="2" ParentId="8245" CreationDate="2014-08-20T11:22:56.707" Score="11" Body="&lt;p&gt;Yes, they have done a lot of testing, hence why they now finally realize that most electronics are of no harm, and you can use them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=15254&quot;&gt;FAA announcement page&lt;/a&gt; has a link to a &lt;a href=&quot;http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=15255&quot;&gt;fact sheet&lt;/a&gt; of their report, as well as a link to the &lt;a href=&quot;http://faa.gov/about/initiatives/ped/media/PED_ARC_FINAL_REPORT.pdf&quot;&gt;PDF&lt;/a&gt; of the report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the FAA report, other agencies have weighed in (&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_10/interfere_textonly.html&quot;&gt;such as Boeing&lt;/a&gt;).  Basically, the rules were instituted in the 1960s, and remained virtually unchanged since then, so it was time to make a change.&lt;/p&gt;&#xA;" OwnerUserId="3268" LastEditorUserId="2171" LastEditDate="2014-08-20T12:33:12.333" LastActivityDate="2014-08-20T12:33:12.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8247" PostTypeId="2" ParentId="8244" CreationDate="2014-08-20T11:25:45.473" Score="11" Body="&lt;p&gt;Many (especially larger) airlines have a history and infrastructure for engines from a specific manufacturer and are unlikely to change that, the cost would extend far beyond just the cost of changing the contract. E.g. KLM has a massive investment in maintenance facilities for GE engines, workshops, spare parts warehouses, highly trained specialised technicians. Retooling to RR would be prohibitive for them. &lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Of course a smaller operation without maintenance facilities of their own might be more flexible in that and just buy whatever is cheapest at the time, contracting out maintenance to various companies as needed. But even then, it's often more economical to have a single maintenance provider doing all your work for you, which might well mean a provider who's specialised in a single series of engines, for example if you're based at Schiphol there's a good chance you'll be contracting out your maintenance to KLM and their GE specialised shops.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So there are many good reasons for airlines to stick with a single engine supplier (and to a degree with a single aircraft manufacturer), even if the cost of buying those engines is higher than selecting competing engines from another manufacturer.&lt;br/&gt;&#xA;Say you're going to save 0.1% in your fuel bills for the 2 new aircraft you're buying to increase the fleet of 20 with other engines you have already (and that's a big if, those engines are pretty close between manufacturers for a specific aircraft). You'd need to fly a LOT for it to be worth building an entire duplicate maintenance network just for those few new aircraft.&lt;br/&gt;&lt;br/&gt;&#xA;Of course if it's part of a long term plan to replace the entire fleet with aircraft using that other manufacturer's engines, that's a different story. But mixed engine fleets tend not to be the most economical way to go, even if on one type manufacturer A is marginally more fuel efficient and on type B manufacturer B is marginally more fuel efficient (and that's what you're going to see, marginal differences only).&lt;br/&gt;&#xA;If you're talking an operation like Delta or United, with hundreds of aircraft of each type, it might be a different story. But then too you're talking about more aircraft with each manufacturer's engines than most other airlines have in total, and they'll have multiple maintenance shops themselves, making it easier to have a facility for each manufacturer (and of course in case of the big US airlines, they tend to have ended up with that in the course of gobbling up other airlines anyway).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-20T11:25:45.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8248" PostTypeId="1" CreationDate="2014-08-20T11:26:22.560" Score="0" ViewCount="95" Body="&lt;p&gt;I want to become a pilot, but as you know, I should take some training course on aviation. Currently I am searching for Aviation Scholarships because I can not sponsor myself. Can you give me some pointers please?  &lt;/p&gt;&#xA;" OwnerUserId="3247" LastActivityDate="2014-08-20T11:51:24.507" Title="Pointers to Aviation Scholarships" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2014-08-20T15:34:07.690" ContentLicense="CC BY-SA 3.0" />
  <row Id="8249" PostTypeId="2" ParentId="8248" CreationDate="2014-08-20T11:51:24.507" Score="1" Body="&lt;p&gt;Scholarships dot com has a list of a few scholarship programs:  &lt;a href=&quot;https://www.scholarships.com/financial-aid/college-scholarships/scholarships-by-type/aviation-scholarships/&quot; rel=&quot;nofollow&quot;&gt;https://www.scholarships.com/financial-aid/college-scholarships/scholarships-by-type/aviation-scholarships/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However I am not sure if you are looking to get aviation training for a career, or for personal fulfilment.  There are also some schools that offer various aviation related programs (Embry-Riddle being the best known in the US).  Some of them may have separate scholarship programs that are not specifically listed on the Scholarships.com site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some places throughout the world that offer &quot;learn to fly&quot; programs.  I have a friend that works for a company that even offers their employees all the coursework and flying required for a private pilot license as a training subsidy (Kollsman, in New Hampshire).&lt;/p&gt;&#xA;" OwnerUserId="3268" LastActivityDate="2014-08-20T11:51:24.507" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8250" PostTypeId="2" ParentId="8244" CreationDate="2014-08-20T12:47:29.200" Score="9" Body="&lt;p&gt;There are obvious costs in having a mixed fleet. Particularly in engineering support infrastructure. But large airlines have less of a problem&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There must be some negotiating advantage in having a mixed fleet, when buying engines the maker knows you can switch more easily than an all-GE airline or all-RR airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take as an example BA, with a &lt;a href=&quot;http://www.britishairways.com/en-gb/information/about-ba/fleet-facts&quot;&gt;fleet of 290 aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Switching&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;BA's first 777s were fitted with General Electric GE90 engines, but BA switched to Rolls-Royce Trent 800s for subsequent aircraft.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways#Fleet&quot;&gt;Wikipedia&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Have an engine maker maintain it's rival's engines?&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;British Airways has agreed to a $2.3 billion engine maintenance contract with General Electric  ... Under the 10-year agreement, GE will be responsible for the maintenance, overhaul and repair for British Airways' RB211-524 and CFM56 engines. The Rolls-Royce RB211 engines power the airline's 57 Boeing 747s and 21 767s. The CFM56 engines power the airline's 34 Boeing 737s and 10 Airbus A320s. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.geaviation.com/press/services/services_20051208.html&quot;&gt;http://www.geaviation.com/press/services/services_20051208.html&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Share costs with other airlines?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Airlines can also share maintenance facilities, which is a way of reducing maintenance costs.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Since January 2012 most heavy maintenance on the Boeing 737-400 Gatwick-based fleet has been done at the Lufthansa Technik maintenance facility in Sofia, Bulgaria&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways#British_Airways_Engineering&quot;&gt;Wikipedia&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Other large airlines&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;AA have a mixed &lt;a href=&quot;https://www.aa.com/i18n/amrcorp/corporateInformation/facts/fleet.jsp&quot;&gt;fleet&lt;/a&gt; of 627 aircraft with  both GE and RR engines.&lt;/li&gt;&#xA;&lt;li&gt;UA have a mixed fleet of 700 aircraft with both GE and &lt;a href=&quot;http://www.rolls-royce.com/news/press_releases/2013/19062013_united_airlines.jsp&quot;&gt;RR&lt;/a&gt; engines&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I think you'd find it hard to come up with a specific figure for switching between GE and RR because it depends very much on arrangements any specific airline has in place (e.g. wet-leasing) and on the terms it is able to negotiate with engine makers and maintenance organisations.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-20T13:24:47.233" LastActivityDate="2014-08-20T13:24:47.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8251" PostTypeId="2" ParentId="8244" CreationDate="2014-08-20T14:47:50.240" Score="7" Body="&lt;p&gt;Switching cost depend a lot on the airline and how they handle their relations with the engine manufacturers. For a well-run airline, switching cost are near zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Big airlines have an interest in keeping a healthy competition alive, and they have an advantage in running engines from all the big engine manufacturers. If all aircraft in the fleet would have engines from the same manufacturer, the airline's negotiating power for future engines would be quite limited. If, on the other hand, they have experience with several manufacturers and could be equally likely to buy from either, they can expect to negotiate steep discounts from all of them. Normal discounts are already 30%, but the real prices are confidential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same goes for airframes, that is the reason why most airlines have a mix of Boeings and Airbuses. Some have political constraints, but the well-run airlines try actively to avoid a monopoly. Exceptions are/were JAL, who are under pressure to buy American only, or in the past Swissair, which had only McDonnell-Douglas aircraft, because the airline was heavily staffed with ex Swiss Air Force pilots who had an unhealthily close connection with that manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is nothing airline-specific, but a basic principle for any good purchasing manager. Manufacturers try to drive switching cost up, and the customers try to drive switching cost to zero.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-20T20:06:53.417" LastActivityDate="2014-08-20T20:06:53.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8252" PostTypeId="1" AcceptedAnswerId="8253" CreationDate="2014-08-20T15:47:49.130" Score="46" ViewCount="61139" Body="&lt;p&gt;This question is only regarding aircraft that seat more than about 100 people. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are cargo holds pressurised these days, what is the situation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are only some pressurized, most, of every single one? Does it depend on the carrier, operating region or are there other variations that matter?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Are cargo holds heated?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Do they have lights? (Aren't some lit for animals?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I've noticed random mentions of &quot;some&quot; of the sections being pressurised. Is this correct? It would seem to me that, if indeed, only &lt;strong&gt;some&lt;/strong&gt; are pressurised then, of course, you absolutely could not &lt;strong&gt;rely&lt;/strong&gt; on your luggage being in a pressurised area.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;and what about Fedex-type cargo-only aircraft?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To be clear, I ask this question re &quot;today&quot; because I noticed when googling on this, there is a lot of information, but only old information (say, 10 yrs old plus). That is a recipe for confusion and urban myth, so the total facts from you experts would be great.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Possibly, it would be difficult to secure accurate online references for this - my quick searching anyway only revealed patchy, out-of-date looking stuffs. Note for example, the Wikipedia article on &lt;a href=&quot;http://en.wikipedia.org/wiki/Cabin_pressurization&quot; rel=&quot;noreferrer&quot;&gt;Cabin Pressurization&lt;/a&gt; has only one poor, no-referenced sentence on the whole matter!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note for example... &lt;a href=&quot;https://travel.stackexchange.com/questions/35490&quot;&gt;Spray bottles (pressurized) in the checked luggage?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3272" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2018-06-15T14:53:10.000" Title="Are cargo holds pressurised these days?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8253" PostTypeId="2" ParentId="8252" CreationDate="2014-08-20T16:59:33.400" Score="56" Body="&lt;p&gt;Aircraft design has not changed &lt;strong&gt;that&lt;/strong&gt; much in the last 10 years. In fact, most aircraft in production 10 years ago are still in production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cargo holds in typical airliners are indeed pressurized. Take a look at a cross section of an airliner (A380 here):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ytbmj.png&quot; alt=&quot;A380 Fuselage Cross Section&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The round shape of the fuselage outline is very efficient at withstanding pressure. Because of that, everything within the fuselage shape is pressurized. This includes the cargo hold below. Only cargo holds located behind the aft pressure bulkhead would be unpressurized, and these are mainly found in smaller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The floor of the passenger cabin is not designed to withstand that pressure, because the flat surface would need to be much heavier to do so. Decompression events &lt;a href=&quot;https://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol1/xml/CFR-2011-title14-vol1-sec25-365.xml&quot; rel=&quot;noreferrer&quot;&gt;are considered by regulations though&lt;/a&gt;, so there are vents that allow the pressure to equalize. In older aircraft without these vents, a decompression event can cause the floor of the cabin to collapse, as in &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_96&quot; rel=&quot;noreferrer&quot;&gt;this incident&lt;/a&gt; (and because it wasn't addressed, &lt;a href=&quot;http://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981&quot; rel=&quot;noreferrer&quot;&gt;this one too&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are cargo holds heated?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sometimes. This will depend on the aircraft type. &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/241772&quot; rel=&quot;noreferrer&quot;&gt;There&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/275381/&quot; rel=&quot;noreferrer&quot;&gt;are&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/75643/&quot; rel=&quot;noreferrer&quot;&gt;many&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/13748&quot; rel=&quot;noreferrer&quot;&gt;threads&lt;/a&gt; over on the TechOps forums about this. The temperature can be adjusted depending on the cargo load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the air outside the plane is cold, the walls are insulated (also for fire protection), and being pressurized along with the cabin helps too. Even in unheated cargo holds, the temperature should be above freezing. For example, &lt;a href=&quot;https://travel.stackexchange.com/q/22604/12976&quot;&gt;the cargo bay of a 767 stays above 7˚C but with heat stays above 18˚C&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do they have lights? (Aren't some lit for animals?)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They do have lights, mainly for ground crew during loading and unloading. See &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_06/textonly/s01txt.html&quot; rel=&quot;noreferrer&quot;&gt;this Boeing page&lt;/a&gt; about fire protection where it mentions that &quot;another safety feature on many newer airplane models prevents the cargo lights from operating in flight&quot;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;and what about Fedex-type cargo-only aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These aircraft are still based on the airliner models (and sometimes converted from airliners). Therefore, they have the same pressurization system. The cabin is still pressurized, or they would have to put in some type of bulkhead behind the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.acp-logistics.com/boeing-b747-400f-charter.html&quot; rel=&quot;noreferrer&quot;&gt;This includes&lt;/a&gt; the cargo version of the 747 (both upper and lower areas are pressurized).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rare exception would be aircraft like the 747 LCF (Dreamlifter). The cargo section &lt;a href=&quot;http://www.boeing.com/news/frontiers/archive/2005/june/ts_sf05.html&quot; rel=&quot;noreferrer&quot;&gt;is not pressurized&lt;/a&gt;, and there is a bulkhead behind the flight deck section.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2015-12-22T17:05:44.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8254" PostTypeId="2" ParentId="3300" CreationDate="2014-08-20T17:50:12.317" Score="4" Body="&lt;p&gt;For clarification on some of the answers, technology in the area of distributed propulsion is moving towards systems that would allow hybrid quadcopters to be built that eliminate the problems of a gas quadcopter and remove the energy density limitations of electric systems. I suspect we will see experimental human scale quadcopters in the next 20-30 years.&lt;/p&gt;&#xA;" OwnerUserId="3273" LastActivityDate="2014-08-20T17:50:12.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8256" PostTypeId="1" AcceptedAnswerId="8257" CreationDate="2014-08-20T20:23:04.973" Score="7" ViewCount="12001" Body="&lt;p&gt;Since the ICAO identifiers B737, B738, and B739 are already taken, what will the ICAO identifier for the 737 MAX 7, 8, and 9 be? Would it possibly be B73M7 etc?&lt;/p&gt;&#xA;" OwnerUserId="3275" LastEditorUserId="19" LastEditDate="2014-08-21T16:10:08.867" LastActivityDate="2017-05-17T17:48:11.407" Title="What will the 737 MAX 7, 8, and 9 ICAO IDs be?" Tags="&lt;boeing-737&gt;&lt;icao&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8257" PostTypeId="2" ParentId="8256" CreationDate="2014-08-20T20:58:03.270" Score="9" Body="&lt;p&gt;The new &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_MAX&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737 MAX&lt;/a&gt; is based on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737 Next Generation&lt;/a&gt; family, which it will replace. Also note that 737 MAX is still under development and is scheduled to release in 2017.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/op3a6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/op3a6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://www.icao.int/publications/DOC8643/Pages/Search.aspx&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first 7 is omitted and the suffix is now an M for Max, e.g. B37M for the Boeing 737 MAX 7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has complete list of ICAO codes &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_ICAO_aircraft_type_designators&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/publications/DOC8643/Pages/Search.aspx&quot; rel=&quot;noreferrer&quot;&gt;ICAO Aircraft Type Designators&lt;/a&gt;: Search for Boeing and you will find 737 MAX in the list.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="14897" LastEditDate="2017-05-09T02:10:29.517" LastActivityDate="2017-05-09T02:10:29.517" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8258" PostTypeId="2" ParentId="8174" CreationDate="2014-08-20T22:33:19.377" Score="3" Body="&lt;p&gt;This NOTAM concerns the fire and rescue level not the ATS operating hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find the description of the fire and rescue levels &lt;a href=&quot;http://www.legifrance.gouv.fr/affichTexte.do?cidTexte=JORFTEXT000000464146&amp;amp;dateTexte=&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reference of the ATS hours is to say the level is raised during the opening hours of the ATS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATS opening hours are available on the &lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/aip/enligne/fr/..%5CPDF_AIPparSSection%5CVAC%5CAD%5C2%5C1410_AD-2.LFAT.pdf&quot; rel=&quot;nofollow&quot;&gt;Visual Access Chart&lt;/a&gt; from the SIA. (French service for aeronautical information)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where you have on last page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;SUMMER 0700 - 1800&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Finally for the language, you have to speak French when the ATS is closed.&lt;/p&gt;&#xA;" OwnerUserId="3277" LastEditorUserId="1696" LastEditDate="2014-08-22T16:28:49.283" LastActivityDate="2014-08-22T16:28:49.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8259" PostTypeId="1" AcceptedAnswerId="9430" CreationDate="2014-08-20T22:59:56.190" Score="18" ViewCount="1418" Body="&lt;p&gt;When a plane is finally considered to not be airworthy, what happens to them?  Do they take them apart bit by bit?  Do they sink them offshore to make them into reefs?  Are parts stripped and sold as spares? Are there legal procedures the airlines have to go through?  What happens?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="6919" LastEditDate="2015-05-21T06:16:08.533" LastActivityDate="2015-05-21T06:16:08.533" Title="How do airlines dispose of a passenger jet when it's no longer airworthy?" Tags="&lt;aircraft-maintenance&gt;&lt;faa&gt;&lt;airlines&gt;&lt;aircraft-disposal&gt;" AnswerCount="4" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8260" PostTypeId="1" AcceptedAnswerId="8265" CreationDate="2014-08-20T23:03:12.990" Score="21" ViewCount="2839" Body="&lt;p&gt;How often (and under what conditions) are airliners resold to another organization with...less stringent qualifications?  Is there a certain number of hours after which an airliner has to be retired or something?  Or is it just that airlines like to buy new and shinier airplanes on occasion?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, when an aircraft is being resold, are there any particular procedures that have to be followed?  And are there different levels of airworthiness involved (ie., you have a lower litmus test if you are just selling it off to be used as a cargo plane or private plane?)&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="6919" LastEditDate="2015-05-21T06:15:44.243" LastActivityDate="2015-05-23T09:03:21.073" Title="Under what conditions do airliners retire aircraft and sell them to other airlines?" Tags="&lt;airline-operations&gt;&lt;faa&gt;&lt;airlines&gt;&lt;aircraft-disposal&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8261" PostTypeId="2" ParentId="8259" CreationDate="2014-08-20T23:12:04.280" Score="5" Body="&lt;p&gt;They send it to a professional demo team that drains the fluids, grabs the spares and cuts up the hull for the materials and send it all to be recycled as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are plenty of youtube videos detailing the process like &lt;a href=&quot;https://www.youtube.com/watch?v=xDxJAO__6t8&quot; rel=&quot;noreferrer&quot;&gt;https://www.youtube.com/watch?v=xDxJAO__6t8&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-08-20T23:12:04.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8262" PostTypeId="2" ParentId="8260" CreationDate="2014-08-21T00:16:29.417" Score="5" Body="&lt;p&gt;To answer your second question, when aircraft are being sold it is common practice to perform a check ride in which the plane is put through a series of less-than-normal flight maneuvers that would reveal possible signs of impending maintenance and/or damage. This (AFAIK) is not a requirement, but rather a good business practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your first question (poorly), it most likely depends on airline policies. Aircraft that are not fit for flight are simply not fit for flight, however airline policies, and/or the economics of retaining specific aircraft may contribute to the sale of airliners. An additional factor may be fluctuations in demand for certain routes, in which cases certain types of aircraft may become less feasible to own (turboprops are more economical for shorter routes, jets are better for longer routes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines also engage in the practice of loaning aircraft to other airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://airinsight.com/2011/08/19/jet-vs-turboprop-a-debate-that-dates-from-the-early-1950s/#.U_WMD7xdUkU&quot; rel=&quot;nofollow&quot;&gt;http://airinsight.com/2011/08/19/jet-vs-turboprop-a-debate-that-dates-from-the-early-1950s/#.U_WMD7xdUkU&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="946" LastEditDate="2014-08-21T12:31:48.717" LastActivityDate="2014-08-21T12:31:48.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8263" PostTypeId="2" ParentId="8260" CreationDate="2014-08-21T00:40:35.103" Score="5" Body="&lt;p&gt;There is a maximum number of flights/flight hours after which the plane needs to retire (aka scrapped for parts). The main reason for this is the metal fatigue by the pressurization cycles. If you ignore that then you have the same issue as &lt;a href=&quot;http://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;nofollow&quot;&gt;Aloha flight 243&lt;/a&gt; meaning the fuselage will simply rip itself apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason an airline sells a plane is if it is strapped for money. And no company is going to buy a used plane when they won't get their investment back.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-08-21T09:14:55.640" LastActivityDate="2014-08-21T09:14:55.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8264" PostTypeId="2" ParentId="8256" CreationDate="2014-08-21T06:39:12.627" Score="1" Body="&lt;p&gt;Initially they will go with the same designators as the B737NG series. If the performance is very different from the NG, new designators may be chosen. I don't think this will be necessary. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that an ICAO aircraft type designator is always 4 characters; B73M7 is too long.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-08-21T06:39:12.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8265" PostTypeId="2" ParentId="8260" CreationDate="2014-08-21T06:57:59.430" Score="28" Body="&lt;p&gt;Some reasons for an airline to sell some of its fleet:&lt;br/&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;they need quick cash (as ratchet freak points out). This usually means the company is in serious trouble&lt;/li&gt;&#xA;&lt;li&gt;they're changing their route network and there's no more need for it (e.g. KLM dropped a lot of very short flights in the 1990s and early 2000s, and got rid of the aircraft that were operating them as they were inappropriate for the longer routes that replaced them)&lt;/li&gt;&#xA;&lt;li&gt;they bought out another airline and have no need for (all) its aircraft, or want to replace them with other types to keep their fleet homogenous (operating many similar types is less economical than operating a smaller number of types)&lt;/li&gt;&#xA;&lt;li&gt;they're splitting part of their operations to a new company set up for the purpose (the new company becoming the new owner of the aircraft, usually for a symbolic fee), for example a regional affiliate or a charter operation&lt;/li&gt;&#xA;&lt;li&gt;it may be more economical to replace the aircraft then to keep them. When NWA decided to replace their DC9 fleet with A320s this was for economic reasons (lower maintenance and fuel cost for example), not because the aircraft had run out of fatigue life. The aircraft were old so most probably were scrapped, but some may well have ended up with airlines in other countries, replacing even older aircraft or expanding existing DC9 fleets there.&lt;/li&gt;&#xA;&lt;li&gt;and some airlines just want to portray a public image of always flying shiny new aircraft. I believe Singapore Airlines used to have a policy like that and replace everything it bought relatively quickly (more so than most other airlines at least). PanAm was like that as well. If you have a reputation of exclusivity, this may add to customers' willingness to pay premium to fly with you&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-21T06:57:59.430" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8266" PostTypeId="1" AcceptedAnswerId="8267" CreationDate="2014-08-21T07:38:23.950" Score="5" ViewCount="1282" Body="&lt;p&gt;The pilots operating manual of our Cessna 182 contains the lift-versus-alpha and lift-versus-drag data of the airplane, so I assume this is data that should be publicly available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a trustworthy resource where I can get the polar curves of different aircraft, especially airliners? I'm looking for that of the Airbus A350 XWB in particular.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="97" LastEditDate="2015-05-03T01:02:23.360" LastActivityDate="2017-07-12T14:38:25.100" Title="How to find polar curves of airliners?" Tags="&lt;lift&gt;&lt;drag&gt;&lt;airbus-a350&gt;&lt;polar&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8267" PostTypeId="2" ParentId="8266" CreationDate="2014-08-21T08:36:44.160" Score="11" Body="&lt;p&gt;Polar curves for older airliners can be found in lecture notes or technical publications. The drag polars of the most recent ones, where no independent measurement is yet possible, are a closely guarded secret. If you see something, it will be restricted such that an important part of the puzzle is missing. For the polars to be meaningful, you need aircraft mass and flight conditions, air temperature and density and sometimes also engine thrust information to make any meaningful comparisons. Also be aware that the Airbus method to determine the reference area is different from Boeing's, but at least those methods are published. Full disclosure is only available to potential customers on the basis of an Non-Disclosure Agreement (NDA).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-21T19:08:23.800" LastActivityDate="2014-08-21T19:08:23.800" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8268" PostTypeId="1" AcceptedAnswerId="8269" CreationDate="2014-08-21T10:03:58.737" Score="24" ViewCount="10397" Body="&lt;p&gt;So I don't have my pilots licence, but I was part of the Australian Air Force Cadets for nearly 8 years (wonderful organisation). During this time I went on a number of flights in Cessna 172's and Cessna 152's. I always noticed that as part of the pre-flight check, the pilot checked both magneto's and this corresponded to a slight RPM drop on the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does the lack of a magneto affect engine RPM?&lt;/p&gt;&#xA;" OwnerUserId="3248" LastEditorUserId="572" LastEditDate="2015-02-19T09:02:39.397" LastActivityDate="2019-07-16T07:36:45.103" Title="Why does the lack of a magneto affect engine RPM?" Tags="&lt;piston-engine&gt;&lt;cessna-172&gt;&lt;cessna-152&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8269" PostTypeId="2" ParentId="8268" CreationDate="2014-08-21T10:27:35.530" Score="46" Body="&lt;p&gt;Firstly, to understand the answer, we need to understand that the Cessna 152's and 172's run a 4 Cylinder, Horizontally-opposed Engine. Each Cylinder has 2 spark plugs, one on the top side of the cylinder head, and one on the bottom side. The spark plug ignites the fuel/air mixture that has been sucked into the engine, and causes a controlled burn to push the piston down the cylinder and turn the crankshaft in turn (hence turning the propeller as it is connected to the end of the crankshaft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, as I've stated, each cylinder has two spark plugs, one connected to the &quot;left&quot; magneto, and one connected to the &quot;right&quot;. If we turn one magneto &quot;off&quot; (or ground it to be politically correct), only one spark plug in each cylinder will &quot;fire&quot; to ignite the fuel/air mixture. This causes the mixture to have a delayed and less effective burn, meaning that the piston does not get pushed down the cylinder as effectively, meaning the crankshaft will not rotate as fast, and hence, leads to a drop in the Propeller RPM (Revolutions per Minute).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We check the magnetos on the ground to check that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A. They both work, and the engine won't die if we lose a magneto (we should be able to return to land on the remaining serviceable magneto)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;B. We are checking that there is no &quot;Spark Plug Fouling&quot;. The fuel we use in aviation contains lead, and hence after a time of running the engine at low power settings on the ground, the lead in the fuel will accumulate on the spark plug head (instead of being burnt off when the engine is working under power), and cause the spark plug to let off a limited spark, or completely block the spark, hence again, making our engine less efficient.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastEditorUserId="18707" LastEditDate="2019-07-16T07:36:45.103" LastActivityDate="2019-07-16T07:36:45.103" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8270" PostTypeId="1" AcceptedAnswerId="8283" CreationDate="2014-08-21T12:10:42.870" Score="8" ViewCount="1797" Body="&lt;p&gt;I have noticed that Air France KLM offer a Maintenence (MRO) service for aircraft and jet engines. This sounds like a potentially big threat to engine manufacturers like Rolls Royce who makes around 50% of its revenue from its TotalCare MRO servicing contracts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would have thought the price of buying saying a Rolls Royce jet engine would be far higher if an airline customer did not take the MRO TotalCare package from RR and in addition the airline may suffer from reduced engine warranties if they employ a 3rd party to service the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you think engine manufacturers business will get competed away by independent MRO businesses like Air France KLM's?&lt;/p&gt;&#xA;" OwnerUserId="3252" LastEditorUserId="19" LastEditDate="2016-07-28T15:02:10.787" LastActivityDate="2017-10-04T18:25:18.227" Title="What is the future of manufacturer independent jet engine maintenance repair and overhaul (MRO) services?" Tags="&lt;jet-engine&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8271" PostTypeId="1" AcceptedAnswerId="8274" CreationDate="2014-08-21T12:16:23.347" Score="7" ViewCount="1055" Body="&lt;p&gt;I just came across &lt;a href=&quot;http://www.baesystems.com/article/BAES_175799/aircraft-set-to-become-more-human-as-engineers-develop-smart-skins-which-can-detect-injury;baeSessionId=tvp4T1pPxB145s0vbnJ30LCxHLmB9fg7hVSSPctQsgXZ869K3hBD!-1101383713?_afrLoop=48610432795000&amp;amp;_afrWindowMode=0&amp;amp;_afrWindowId=null#%40%3F_afrWindowId%3Dnull%26_afrLoop%3D48610432795000%26_afrWindowMode%3D0%26_adf.ctrl-state%3Dfqn2y0lsp_4&quot; rel=&quot;noreferrer&quot;&gt;this article&lt;/a&gt; on LinkedIn, and I have a few questions about it.&lt;/p&gt;&#xA;&lt;p&gt;Some of BAe's claims are things such as:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Aircraft set to become more human as engineers develop smart skins which can detect injury&lt;/p&gt;&#xA;&lt;p&gt;The revolutionary ‘smart skin’ concept will enable aircraft to continually monitor their health, reporting back on potential problems before they become significant. This would reduce the need for regular check-ups on the ground and parts could be replaced in a timely manner, increasing the efficiency of aircraft maintenance, the availability of the plane and improving safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the past I have seen some claims of a similar nature (such as skin that adapts its shape to be more aerodynamic based on phase of flight).  What I am wondering is:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this really technically feasible?&lt;/li&gt;&#xA;&lt;li&gt;Can such a skin really do what BAE claims?&lt;/li&gt;&#xA;&lt;li&gt;Will this have any &lt;em&gt;adverse&lt;/em&gt; effects on the aviation industry? (Usually people are so enamored with new technology and the good it can do, I am more curious if anyone has thought of the downside.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3268" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-03T01:04:46.957" Title="How feasible is BAE Smart Skin?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8272" PostTypeId="1" CreationDate="2014-08-21T12:23:38.050" Score="8" ViewCount="1442" Body="&lt;p&gt;I met someone the other day who owns a small plane and he was going to fly from Cambridge to the Isle of Wight.  I asked him whether he had to file a flight plan and he said no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just wondering therefore how such collisions are prevented?&lt;/p&gt;&#xA;" OwnerUserId="3284" LastEditorUserId="97" LastEditDate="2014-08-21T22:57:15.553" LastActivityDate="2015-08-19T13:04:47.460" Title="What system is there in the UK to prevent collisions between small aircraft?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;easa-regulations&gt;&lt;uk&gt;" AnswerCount="6" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8273" PostTypeId="2" ParentId="8272" CreationDate="2014-08-21T12:41:30.590" Score="11" Body="&lt;p&gt;Small airplanes will be under VFR (Visual Flight Rules) which entails that the pilot looks out the window and is responsible for staying away from other aircraft and staying out of the clouds (the fog banks of the sky). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you see another plane in your path then there are standard rules to avoid him see &lt;a href=&quot;https://aviation.stackexchange.com/questions/3575/which-way-should-you-turn-to-avoid-another-aircraft&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can fly under IFR (Instrument Flight Rules) but that requires that Air traffic control monitors the airplane and steers it away from other planes.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-08-22T10:49:40.417" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8274" PostTypeId="2" ParentId="8271" CreationDate="2014-08-21T13:14:35.893" Score="14" Body="&lt;p&gt;Smart skins are at least 20 years old and, like fusion energy, just around the corner since then. The usual concept is to embed optical fibers in the structure and shine laser pulses through them. If the fiber is damaged, it will transmit less light, and by measuring the return time of a very short laser pulse, even the location of the damage can be detected. This concept requires fibers with the same break elongation as the load-carrying material, so they break just when a crack in the structure starts. To detect even small cracks, a lot of fibers must be evenly placed, which is only possible with fiber reinforced plastics. The effort to place a light source and a detector at each end of every fiber has so far prevented a practical application, at least to my knowledge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other techniques send clearly defined &quot;pings&quot; through the material and detect the propagation of the sound wave with a number of microphones. By comparing the measured signal with a reference signal, damage can be detected in metal structures as well. This technique needs some processing power, but is easily within the scope of modern microcontrollers. However, outside noise will interfere with the measurement, so it needs well defined conditions to be effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downside would be more mass, investment and operator training. Generally, more advanced techniques for structural health checks have been steadily introduced in the last 80 years. Given the high cost of maintenance today, I expect that deployed damage detection technology will continue to advance, with a healthy time gap to what is possible in the laboratory. So there is some truth to those BAe claims, but I would hardly call it revolutionary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even more advanced are concepts of self-healing structures which contain capsules of a two-component resin. When the structure breaks, the capsules break as well and the freed resin helps to mend the crack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ask me, the mass of those microcapsules would be better invested if it carries load right from the start, so the structure will tolerate higher loads and more load cycles. But I guess those research grants need to be spent somehow, and marketing departments need to write about revolutionary discoveries on a regular basis.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-21T13:26:13.867" LastActivityDate="2014-08-21T13:26:13.867" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8276" PostTypeId="2" ParentId="8271" CreationDate="2014-08-21T14:09:30.087" Score="3" Body="&lt;p&gt;If they ever get it to work on a production scale (and that's a big if) and economical to implement, it could mean aircraft detecting hairline fractures caused by metal fatigue themselves, rather than relying on regular X-ray scans of their structural components.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;But that's for the future. For now the main application is the generation of funding for more research, which is the main application of most all research done in the last 20 years or more. Hence the mandatory phrase &quot;more research is needed&quot; at the end of every report coming out of every research department.&lt;br/&gt;&#xA;I once committed the mortal sin of not including that in a report, in fact I made it quite clear in my report that no further research into the topic was needed because the whole concept was bonkers and not economically viable (I was slightly more political in my wording but not all that much). It wasn't received kindly by the people who'd ordered the research, nor by its funders. It did get quite a few chuckles from my then colleagues outside of the specific department, there being little love lost between them and the team lead of the project I had been working on for the last 6 months as an intern.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So yes, it can in theory have very interesting implications for aircraft maintenance procedures, in practice though I seriously doubt we'll see any of it in more than a proof of concept form for a very long time.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-21T14:09:30.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8277" PostTypeId="2" ParentId="8270" CreationDate="2014-08-21T14:57:18.880" Score="1" Body="&lt;p&gt;The MRO can do &quot;simple&quot; operations on a engine, like engine wash or borescope inspection; but if the operation is more complicated like complete revision, you have to send the engine to &quot;shop visit&quot; that's mean to the manufacturer.&#xA;Sometimes the manufacturer send employee to the MRO place to do the work when this work don't need special tools.&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="3039" LastEditDate="2014-08-21T15:16:08.483" LastActivityDate="2014-08-21T15:16:08.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8278" PostTypeId="2" ParentId="8088" CreationDate="2014-08-21T15:23:11.107" Score="9" Body="&lt;p&gt;According to ICAO NAT doc 007 (North Atlantic Operations and Airspace Manual, edition 2014/2015) (&lt;a href=&quot;http://www.icao.int/EURNAT/EUR%20and%20NAT%20Documents/NAT%20Documents/NAT%20Doc%20007/_NAT%20Doc007_Edition%202014-2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;PDF&lt;/a&gt;), approximately half of the North Atlantic (NAT) flight use the Oceanic Track System (OTS).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.1.3:&lt;/em&gt;&lt;/strong&gt; It should be appreciated, however, that use of OTS tracks is not&#xA;  mandatory. Currently about half of NAT flights utilise the OTS.&#xA;  Aircraft may fly on random routes which remain clear of the OTS or may&#xA;  fly on any route that joins or leaves an outer track of the OTS. There&#xA;  is also nothing to prevent an operator from planning a route which&#xA;  crosses the OTS. However, in this case, operators must be aware that&#xA;  whilst ATC will make every effort to clear random traffic across the&#xA;  OTS at published levels, re-routes or significant changes in flight&#xA;  level from those planned are very likely to be necessary during most&#xA;  of the OTS traffic periods.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that not all flights in the NAT do cross the Atlantic from East to West or vice versa. For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Flights from Northern Europe to Spain / Canaries / Portugal and v.v.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flights from Portugal to the Azores and v.v.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flights from Iceland&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And then there are a number of fixed routes that allow aircraft that do no meet the minimum navigation performance requirements to cross the ocean. These tracks do not change with the daily winds like the OTS tracks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aGqxe.jpg&quot; alt=&quot;Fixed routes in the NAT&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All these are included in the 'about half'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But especially in the Northern part of the NAT airspace, covered by the Reykjavik FIR there are many random routes. According to the website of &lt;a href=&quot;http://www.isavia.is/english/air-navigation/reykjavik-area-control-centre/north-atlantic-organized-track-system-(nat-ots)/&quot; rel=&quot;noreferrer&quot;&gt;Iceavia:&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 2010, 92.3% of the traffic in the Reykjavik CTA was on random&#xA;  tracks and 7.7% was on the NAT tracks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But that is mainly because the OTS tracks are usual south of the Reykjavik FIR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That same page says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In effect, where the preferred track lies within the geographical&#xA;  limits of the OTS, the operator is obliged to choose an OTS track or&#xA;  fly above or below the system. Where the preferred track lies clear of&#xA;  the OTS, the operator is free to fly it by nominating a random track.&#xA;  Trans-Atlantic tracks, therefore, fall into three categories: OTS,&#xA;  Random or Fixed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-07T08:02:08.020" LastActivityDate="2015-09-07T08:02:08.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8279" PostTypeId="2" ParentId="8272" CreationDate="2014-08-21T15:40:30.107" Score="5" Body="&lt;p&gt;Glider student here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no electronic or administrative system which can replace pilot vigilance.  In the US (I am not familiar with the regulations anywhere else), the end responsibility to avoid other aircraft ALWAYS falls with the pilot in command, even when given clearance/directions from ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are systems to help though.  Popular with glider pilots (especially in Europe, but increasingly in the US) there is a system called &lt;a href=&quot;http://en.wikipedia.org/wiki/FLARM&quot; rel=&quot;noreferrer&quot;&gt;FLARM&lt;/a&gt; which broadcasts GPS and baromatric data.  Other aircraft with FLARM units within range receive this signal and selectively warn the pilot of collision hazards.  FLARM has a number of shortcomings which pilots must be mindful of; eg: aircraft without a FLARM unit are not tracked, it has limited range so it isn't very helpful for distant or fast-moving aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2791" LastEditorUserId="1289" LastEditDate="2014-08-21T19:55:28.423" LastActivityDate="2014-08-21T19:55:28.423" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8280" PostTypeId="2" ParentId="8266" CreationDate="2014-08-21T16:24:09.900" Score="1" Body="&lt;p&gt;You may choose to download &lt;a href=&quot;http://max.kellermann.name/download/xcsoar/devel/Polaren.xls&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Excel spreadsheet&lt;/a&gt; which contains a list of over 100 glider performance figures in the tab &quot;Gliders&quot; . The spreadsheet allows comparison  of two aircraft **Polar Curves*.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing and Airbus does not make public the figures pertaining to Drag Polar Rates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find some assumptions &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/B747PresS07.pdf?q=747&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="21864" LastEditDate="2017-07-12T03:34:30.413" LastActivityDate="2017-07-12T03:34:30.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8281" PostTypeId="1" AcceptedAnswerId="8282" CreationDate="2014-08-21T19:14:13.857" Score="30" ViewCount="6545" Body="&lt;p&gt;Describing lift as the result of &quot;equal transit time&quot; on both sides of an airfoil is a fallacious theory widely found in technical books and articles for general public (see below for details about this explanation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But such explanation is also found in aviation books, in spite being identified by &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/wrong1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA&lt;/a&gt; as an incorrect theory (NASA explains that if lift is computed from fluid laws, based on airspeed on both sides of the airfoil, the result will not be in line with what is observed in real life).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this very popular theory also taught this way in flight schools? (please note the question is about pilot teaching, not about &lt;a href=&quot;https://aviation.stackexchange.com/q/16193/3201&quot;&gt;what is lift&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Annex: &lt;em&gt;Popular explanation of lift from equal transit time&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supporters of this theory explain aerodynamic lift results from the differential of pressure between lower and upper sides of a wing created by Bernoulli principle. They say:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Air has to move a longer distance on the upper side because of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfoil&quot; rel=&quot;nofollow noreferrer&quot;&gt;curve of the profile&lt;/a&gt; (not correct for all wing profiles).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Both sides must be traveled in an equal amount of time so that air molecules that were nearby ahead of the wing, will meet again behind it (may be right or wrong.)&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xgvJC.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xgvJC.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By &lt;a href=&quot;http://en.wikipedia.org/wiki/Bernoulli%27s_principle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bernoulli's principle&lt;/a&gt; accelerated airflow has lower pressure. Pressure is then lower on top of the wing, and higher on bottom. Hence the wing receives a force which has a vertical component upward. This component balances the weight of the aircraft, and allows to stay aloft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-07-07T13:56:32.630" LastActivityDate="2019-07-07T13:56:32.630" Title="Principle of aerodynamic lift: are misconceptions also taught in flight schools?" Tags="&lt;aerodynamics&gt;&lt;flight-training&gt;&lt;theory&gt;&lt;lift&gt;" AnswerCount="4" CommentCount="14" FavoriteCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="8282" PostTypeId="2" ParentId="8281" CreationDate="2014-08-21T20:35:50.173" Score="10" Body="&lt;p&gt;I can only speak on behalf of the Australian Syllabus as put out by CASA (Civil Aviation Safety Authority - Australia), but we are expected to teach both Bernoulli's Theorem, and the Theorem of Air Deflection (I believe this is the second theory you are talking about in regards to Newton's Laws).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BUT, we are also expected to teach these items as theories, not laws, as there is no law on the creation of lift. So to a degree, you could say we do teach misconceptions, but also at the same time we openly acknowledge those misconceptions to those we are teaching.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other part we openly admit is that both theories have merit to at least help understand certain important characteristics of Aerodynamics in-flight, great example is a stall. We have the Centre of Pressure that moves further forward along the Wing Chord as the Angle of Attack is increased, due to the &quot;peak&quot; of dynamic air pressure being more forward along the wing chord. At the &quot;Critical Angle&quot; in is at its most forward position. As soon as we exceed the Critical Angle, the wing is stalled and instantaneously, the Centre of Pressure moves aft along the chord line to a position approximately half way along the chord due to Bernoulli's theorem no longer having the principle effect on our wing. Now the theorem of air deflection takes over, and we look at using the &quot;hand out the window of a moving car&quot; analogy.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2014-08-21T20:35:50.173" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8283" PostTypeId="2" ParentId="8270" CreationDate="2014-08-21T20:54:22.993" Score="13" Body="&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt;&#xA;These days, Rolls-Royce is not any more in the business of selling engines, but &lt;a href=&quot;http://www.economist.com/node/12887368&quot; rel=&quot;nofollow noreferrer&quot;&gt;selling thrust&lt;/a&gt;. The engines send telemetry data to four centers, the biggest one in Derby, in Great Britain, where every engine is under surveillance. An inspection can be scheduled at or spare parts can be directed to the right destination even before the pilots or the airline know that one of their engines has a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By now, 80% of Rolls-Royce engines are sold at a loss which is recouped by a hourly fee paid under the &lt;a href=&quot;http://www.som.cranfield.ac.uk/som/dinamic-content/media/Executive%20Briefing%206%20-%20RR%20Totalcare%20-%20Mtg%20the%20Needs%20of%20Key%20Customers%20%20-%208%20Mar%2010%20v9.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;TotalCare (.pdf!)&lt;/a&gt; program, and that center in Derby is monitoring maybe 4000 of them at the same time. Rolls-Royce has accumulated a treasure of engine operations data, which enables it to consult airlines on best practices. This makes it very hard for a third party to steal maintenance business from Rolls-Royce. All maintenance cost is covered by the TotalCare fee which now accounts for more than half of Rolls-Royce's revenue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other engine manufacturers have begun to copy this approach, and both Airbus and Boeing now offer similar programs for airframe surveillance and maintenance to their customers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder how Air France KLM can get at the data from the engines. My impression is that Rolls-Royce is in a different position, and third parties cannot compete on an equal basis. Airlines can rent out their shop capacity to others, but the specific business model of Rolls-Royce is directly coupled to them being the manufacturer of those engines and owner of the data it creates.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-02T23:03:07.097" LastActivityDate="2017-10-02T23:03:07.097" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8284" PostTypeId="2" ParentId="8281" CreationDate="2014-08-22T03:17:10.023" Score="19" Body="&lt;p&gt;I am a CFI who teaches at a large (+200 students) flight school in the United States.  You might be surprised to hear this, but...&lt;/p&gt;&#xA;&lt;h2&gt;We really don't worry about how a wing works that much.&lt;/h2&gt;&#xA;&lt;p&gt;As far as I'm concerned, the technical explanation for &lt;a href=&quot;http://www.urbandictionary.com/define.php?term=PFM&amp;amp;defid=7233425&quot; rel=&quot;noreferrer&quot;&gt;how a wing works&lt;/a&gt; is a subject for the engineers who build and design such things.  Private pilot applicants (at least all of the ones that I have met) are more concerned with things like &amp;quot;How do I get the plane into the air??&amp;quot; and &amp;quot;What do I do if it starts coming back down again in a hurry?&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;In fact, &lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/com/0070696330&quot; rel=&quot;noreferrer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Van Sickle's Modern Airmanship&lt;/a&gt; starts off the chapter on aerodynamics by saying (paraphrased):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Some of the concepts presented in this chapter are wrong, but they are useful illustrations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, to answer your question, we teach that:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The alignment of the wing to the relative wind displaces air downward, which creates lift.&lt;/li&gt;&#xA;&lt;li&gt;Because of the shape of the airfoil, air on top of the wing has a lower pressure than air below the wing, which also causes lift.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;And unless a student asks us for more information, we leave it at that.&lt;/p&gt;&#xA;&lt;p&gt;If you hope to become an aircraft designer or research fluid dynamics, you'll quickly be corrected of any misconceptions you may have about Mr. Bernoulli and his asymmetric wing.  Most student pilots, however, are satisfied with a pre-discussion &amp;quot;&lt;em&gt;What we'll talk about today isn't technically correct, but you'll find it a lot easier to understand the necessary concepts this way.&lt;/em&gt;&amp;quot;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Peter Kämpf made a worthwhile comment:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;It is really not so hard to understand aerodynamics correctly, and you&#xA;make it sound as if you prefer a short term gain over a profound basis&#xA;which could help pilots to really understand what happens with their&#xA;plane and to select the most appropriate action.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Which is very true - it's not difficult to understand aerodynamics correctly.  I'll defend my viewpoint with an analogy:  Consider a store where you are shopping with a child who doesn't yet understand decimal addition.  You have two purchases, one costing &lt;code&gt;$5.08&lt;/code&gt; and one costing &lt;code&gt;$3.99&lt;/code&gt;.  The child adds the big numbers and tells you that the final price will be &lt;code&gt;$8&lt;/code&gt;. You now have (at least) two choices: you could begin a discussion of significant figures and fractional multiplication (can't forget tax!), or you could praise the child for applying the skills they do have and getting an answer which is pretty close.&lt;/p&gt;&#xA;&lt;p&gt;Is it better if the child eventually understands how to calculate tax rather than simply trusting what the cashier reads off the screen?  Of course.  But &lt;em&gt;at the stage where most of my students are&lt;/em&gt;, it's much more valuable to their development as pilots to simply praise them for being close enough.&lt;/p&gt;&#xA;&lt;p&gt;As regards JAL123, I am in 100% agreement with you.  By the time you as a pilot have progressed sufficiently in your development to be flying something with a turbine pushing it, you should &lt;em&gt;certainly&lt;/em&gt; know the principles and concepts of your machine to the highest degree of accuracy.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-05-08T21:33:55.757" CommentCount="14" ContentLicense="CC BY-SA 4.0" />
  <row Id="8285" PostTypeId="2" ParentId="8271" CreationDate="2014-08-22T13:27:34.353" Score="1" Body="&lt;p&gt;I believe there is a prototype panel already in existence so the answer is yes it is possible...it's just a case of improving upon it and getting it onto a real plane&#xA;Also, you wouldnt want to use ant form of wiring (including optic cables) as that it big costs, and also would compromise the structure, and what happens if you break one of the bits?&lt;/p&gt;&#xA;" OwnerUserId="3297" LastActivityDate="2014-08-22T13:27:34.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8286" PostTypeId="2" ParentId="8259" CreationDate="2014-08-22T15:03:15.190" Score="4" Body="&lt;p&gt;FedEx has lately been donating their 727 retired fleet to flight schools and training departments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://news.van.fedex.com/fedex-donates-boeing-727-trinidad-tobago-civil-aviation-authority&quot; rel=&quot;nofollow&quot;&gt;FedEx Donates Boeing 727 to Trinidad &amp;amp; Tobago Civil Aviation Authority&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://miami.cbslocal.com/2014/04/02/fedex-donates-retired-boeing-727-to-broward-aviation-dept/&quot; rel=&quot;nofollow&quot;&gt;FedEx Donates Retired Boeing 727 To Broward Aviation Dept&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-08-22T15:03:15.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8287" PostTypeId="2" ParentId="7986" CreationDate="2014-08-22T16:20:50.233" Score="3" Body="&lt;p&gt;If you have the call sign, or Air Carrier flight number, you can track flights with &lt;a href=&quot;http://flightaware.com&quot; rel=&quot;nofollow&quot;&gt;http://flightaware.com&lt;/a&gt;. Air Carriers are required to file IFR flight plans so the destination is in the system and trackable. Part 91 (general aviation) and Part 135 (non-scheduled for hire) IFR flights also file a flight plan and their origin and destination are trackable. Most Part 135 flights are on an IFR flight plan but most Part 91 flights are not. However, Operators can block the release of information so FlightAware may not have the info for some aircraft. The information is also available if Part 91 fliers are receiving flight following. If a Part 91 operator is not in contact with ATC the information will not appear in FlightAware.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FlightAware gets the info from the FAA, so there must be an API for it but I don’t know anything about it. “Flightradar24 has a network of more than 3,000 ADS-B receivers around the world that receives plane and flight information from aircraft with ADS-B transponders and sends this information to our servers.” It also gets data directly from the FAA radar with a 5 minute delay.&lt;/p&gt;&#xA;" OwnerUserId="1110" LastActivityDate="2014-08-22T16:20:50.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8288" PostTypeId="1" AcceptedAnswerId="8301" CreationDate="2014-08-22T18:14:16.597" Score="2" ViewCount="1525" Body="&lt;p&gt;From what I understand, an aircraft's &lt;em&gt;registration&lt;/em&gt; number is its ICAO code in the pattern found here: &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_registration#List_of_countries.2Fregions_and_their_registration_prefixes_and_patterns&quot; rel=&quot;nofollow&quot;&gt;Wikipedia: Aircraft registration&lt;/a&gt;, but I have seen references to aircraft using a 3-letter code (I'm assuming it's an &lt;a href=&quot;http://en.wikipedia.org/wiki/Airline_codes#ICAO_airline_designator&quot; rel=&quot;nofollow&quot;&gt;airline code&lt;/a&gt;) followed by a 4-digit number. (Example: PAK0032) What kind of a number could that be?&lt;/p&gt;&#xA;" OwnerUserId="2825" LastActivityDate="2014-08-23T11:48:50.407" Title="What kind of identification code is this format? (AAA0000)" Tags="&lt;air-traffic-control&gt;&lt;icao&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8289" PostTypeId="1" AcceptedAnswerId="8290" CreationDate="2014-08-22T18:26:18.903" Score="18" ViewCount="59348" Body="&lt;p&gt;A few days ago I was on a flight from SFO to AUS (Airbus 320) and I was shocked by the steep angle of descent into AUS. I have been on over a hundred commercial flights but I've never experienced such a steep descent. I checked the flight on flightaware.com and noticed that the descent rate was 3,000 to 4,000 fpm. On other days the descent rate is closer to 2,500 fpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flightaware data: &lt;a href=&quot;http://flightaware.com/live/flight/UAL265/history/20140820/2037Z/KSFO/KAUS/tracklog&quot;&gt;My flight&lt;/a&gt; vs &lt;a href=&quot;http://flightaware.com/live/flight/UAL265/history/20140821/2037Z/KSFO/KAUS/tracklog&quot;&gt;another flight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two questions about this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is considered a &quot;normal&quot; descent rate for the A320?&lt;/li&gt;&#xA;&lt;li&gt;What could be the reason for the exceptionally steep descent compared to a normal flight?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4" LastEditorUserId="19" LastEditDate="2016-10-17T13:28:02.597" LastActivityDate="2017-02-20T06:46:00.893" Title="What is the normal descent rate for airliners?" Tags="&lt;air-traffic-control&gt;&lt;airbus-a320&gt;&lt;descent&gt;" AnswerCount="6" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8290" PostTypeId="2" ParentId="8289" CreationDate="2014-08-22T19:13:48.477" Score="16" Body="&lt;p&gt;There are a few possibilities, there's no way to know which is correct without more information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There could have been an emergency on board. If someone is showing signs of a serious illness pilots will get the plane on the ground in a hurry to get the person medical attention as soon as they can. Or there could have been an issue with the airplane or a passenger, like someone very drunk and unruly in first class, say&lt;/li&gt;&#xA;&lt;li&gt;As @falstro said it could have been a slam-dunk approach, where a controller directs airplanes to do steeper descents to solve sequencing issues. Pilots know if they say &quot;unable&quot; that they probably won't get another approach for awhile, so they'll accept a steep descent to get on the ground sooner&lt;/li&gt;&#xA;&lt;li&gt;It could have been a request of the pilots for a non-emergency reason, like them trying to make up scheduling time, or to stay within fuel limits&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-08-22T19:13:48.477" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8291" PostTypeId="2" ParentId="8289" CreationDate="2014-08-22T21:20:50.983" Score="5" Body="&lt;p&gt;Given the noise abatement initiatives at AUS, it could be a voluntary procedure, usable depending on conditions.  (Steep ascents are sometimes used for this reason at airports with noise issues.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the data, the steep descent rate (3960, 3840 fpm) was only for a couple of minutes near the start of the descent.  True, next day's flight didn't exceed 3000 fpm, but the previous day's got to 3660 fpm for a couple of minutes, so your flight doesn't look way out of line.  In fact, the odd feature of your flight seems rather to have been the extremely slow ascent, almost half the typical climb rate.&lt;/p&gt;&#xA;" OwnerUserId="3300" LastActivityDate="2014-08-22T21:20:50.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8292" PostTypeId="1" AcceptedAnswerId="8294" CreationDate="2014-08-22T21:31:16.110" Score="14" ViewCount="2896" Body="&lt;p&gt;I'm considering getting a private pilot license. From what I've read, pilot error is the leading cause of major airline crashes -- such as on &lt;a href=&quot;http://www.planecrashinfo.com/cause.htm&quot; rel=&quot;noreferrer&quot;&gt;this page&lt;/a&gt;, but that's for major commercial carriers. As the pilot, pilot error is something that I can address myself. One of the things that concerns me is the chance for an accident due to circumstances &lt;i&gt;beyond&lt;/i&gt; my control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the cause breakdown for general aviation accidents? What are the most common mechanical failures?&lt;/p&gt;&#xA;" OwnerUserId="3047" LastEditorUserId="3047" LastEditDate="2014-08-27T18:50:20.247" LastActivityDate="2018-01-31T21:11:39.337" Title="What are the major non-pilot causes of GA accidents?" Tags="&lt;safety&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8293" PostTypeId="2" ParentId="8292" CreationDate="2014-08-22T21:56:59.543" Score="8" Body="&lt;p&gt;Here is a &lt;a href=&quot;http://www.ghafi.org/download/GA-Analysis.1.pdf&quot;&gt;good analysis&lt;/a&gt; that is a bit dated but should be relevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data is from 1985-1995, 160,000 planes and 20,000,000 flight hours&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accident causes:&lt;br&gt;&#xA;Pilot related: 80%&lt;br&gt;&#xA;Mechanical/maintenance: 16%&lt;br&gt;&#xA;Other: 2%&lt;br&gt;&#xA;Unknown: 2%&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The focus is mainly on pilot error (which is an interesting read). The breakdown of the mechanical/maintenance issues is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine/Prop: 70%&lt;br&gt;&#xA;Gear/Brakes: 15%&lt;br&gt;&#xA;Oil system: 5%&lt;br&gt;&#xA;Controls/airframe: 2%&lt;br&gt;&#xA;Fuel System: 3%&lt;br&gt;&#xA;Electrical/Ignition: 3%&lt;br&gt;&#xA;Vacuum Sys/Instruments: 2%&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NTSB has a lot of data available either in &lt;a href=&quot;http://www.ntsb.gov/data/aviation_stats_2012.html&quot;&gt;reports&lt;/a&gt; or by &lt;a href=&quot;http://www.ntsb.gov/aviationquery/index.aspx&quot;&gt;database query&lt;/a&gt;. The reports only break mechanical issues down to powerplant/non-powerplant. During &lt;a href=&quot;http://www.ntsb.gov/doclib/reports/2011/ARA1101.pdf&quot;&gt;2007-2009&lt;/a&gt; it was about &lt;strong&gt;80% powerplant, 20% non-powerplant&lt;/strong&gt; for personal flying. Other types of flying had various distributions. If you consider oil and fuel as powerplant systems, then it's about the same as the data above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally, from reading through many GA accident reports where maintenance was a factor, a lot of things come up after a maintenance visit. Things not attached properly/securely, not done correctly. So having good maintenance, and doing a very thorough check afterwards, will help.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-08-22T22:21:22.003" LastActivityDate="2014-08-22T22:21:22.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8294" PostTypeId="2" ParentId="8292" CreationDate="2014-08-22T22:07:01.417" Score="14" Body="&lt;p&gt;For a statistical overview of General Aviation accidents I suggest checking out the &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Accident-Analysis/Joseph-T-Nall-Report&quot;&gt;Joseph T. Nall Report&lt;/a&gt; prepared by the AOPA Air Safety Institute. Everything I'm citing below comes from the most recent report (the 23&lt;sup&gt;rd&lt;/sup&gt; report, covering 2011). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The leading causes of accidents in 2011 were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Pilot Error&lt;/strong&gt; - About 77%&lt;br&gt;&#xA;This includes poor flight planning, weather encounters, and a host of other things that we could at least theoretically avoid if we actually &lt;em&gt;did&lt;/em&gt; the things we were taught to do in training.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Mechanical or Maintenance related&lt;/strong&gt; - About 13%&lt;br&gt;&#xA;This includes engine failures, control system problems, landing gear failures, etc.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The largest chunk of mechanical failures are &quot;powerplant failures&quot;, which account for 38% of the mechanical failures, or a bit under 5% of total accidents.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Everything Else&lt;/strong&gt; - About 10%&lt;br&gt;&#xA;This includes freak occurrences like a flight instructor &quot;walking into a moving propeller&quot; (I kid you not, it's in the report!). A large chunk of these are also engine failure for causes that could not be determined.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If we add all the engine/powerplant failures together (the explainable ones from &quot;Mechanical&quot; plus the unexplained ones from &quot;Everything Else&quot;) they come out to be  11.5% of total accidents, and are statistically the number two cause of Non-Commercial General Aviation accidents after &quot;Pilot Error&quot;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-22T22:07:01.417" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8295" PostTypeId="2" ParentId="8289" CreationDate="2014-08-22T22:46:23.907" Score="1" Body="&lt;p&gt;First of all, don't take the altitudes and descent/climb rates as fact from FlightAware, they could be pulling from different sources with different time delays or time keeping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons for higher rate of descent at the initial part of descent, could be anything from a late handoff from a previous center sector, to restricted/military areas being active, or having to wait til late to start a descent. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal decent rate varies... but I'd say an average of around 2000-2500 feet per minute.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-08-22T22:46:23.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8297" PostTypeId="2" ParentId="8288" CreationDate="2014-08-23T06:50:53.033" Score="3" Body="&lt;p&gt;The registration for an aircraft follows the nation's letter assigned by ICAO, correct. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this is not the only instance where ICAO is used. When the registration is not used as the radio callsign for the aircraft, They will use the flight number to address the aircraft on the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight callsigns do not always follow the flight number you see on your ticket, especially since the radio callsign uses the ICAO code for the airline instead the IATA code on your ticket. Some airlines even replace parts of the flight number, either to avoid similar callsign at the samw time or to obfusticate which flight it is.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;LH4892 could be known to ATC as DLH48RA &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some transponders can be programmed to broadcast the flight number if they operate with ADS-B. In these cases they carry a specific hexadecimal value, which can look similar to the code you posted, but can have the hexadecimal values in any place and not only the letters in front.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-08-23T06:50:53.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8298" PostTypeId="2" ParentId="2622" CreationDate="2014-08-23T07:22:50.347" Score="-1" Body="&lt;p&gt;There are certain restrictions due to which the airliner didn't give you the seat even if you were ready to pay extra for it (Depends on the operations policy by the manufacturer and the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's mostly the weight restrictions for the flight to take-off as there might be some obstacle for the flight during take-off(hoarding on the end of runway, climate etc.). If the weight is too much then it will result in a disaster so equal weight distribution is mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover in the end it's airliner which has to suffer because the seat occupancy get's affected and it has huge losses incurred by not leaving to its capacity.&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="100" LastEditDate="2014-10-22T11:11:28.580" LastActivityDate="2014-10-22T11:11:28.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8299" PostTypeId="2" ParentId="8214" CreationDate="2014-08-23T07:42:29.040" Score="1" Body="&lt;p&gt;I can offer you some advice as I had the same dilemma before I took my first flight.  If you ignore the physical requirements, of which there are only a few restrictions - basically they want to know if you have any condition that will allow you to become incapacitated - for example, epilepsy; and that you are in a fit mental state - the other things you might want to keep in mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You need to have a good command of English; as this is the language of aviation. Perhaps not a requirement if you are a native English speaker - but you need to be able to understand the instructions from traffic control quickly and relay them back. Don't be afraid to tell them you are a student and they (might) go slow on you.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You need to be able to strictly memorize and follow directions. I know this sounds like one of those things that you would need on any job; but being a pilot one small goof in the checklist can end up with a disaster.  If you are a glutton for procedures and steps, man is this the place for you!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You can't daydream. As my instructor at the time said &quot;you need to be ahead of the plane&quot;, meaning if you are already anticipating what the plane will do, if something sudden comes up you can manage.  It is insane how many things you have to keep track of especially if you are in a trainer aircraft like a 172 that doesn't have a full electronic cockpit or autopilot as in most commercial aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If you want to be a recreational pilot then that's all there is. Once you get the basic hang of what goes on in a flight, then all you have to do is keep up your hours and get type rated for the kind of aircraft you want to fly (dual engine, turboprop, jet, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Go for it!&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-08-23T07:42:29.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8300" PostTypeId="2" ParentId="8281" CreationDate="2014-08-23T09:54:20.863" Score="1" Body="&lt;p&gt;I would like to add my $.02 to this question. Lift is defined (in the aerodynamic texts) as the upward component of the force that the air exerts on the wing. The force is composed of the tangential (sheer) forces that tend to contribute mostly to drag, as well as the pressure (normal) forces that tend to contribute to lift. As for designing the most efficient wing, the answer is trial and error. Hundreds of different mathematically-defined airfoils are put into a wind tunnel and their lift and drag coefficients are measured. They are then published in a book like &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0486605868&quot; rel=&quot;nofollow&quot;&gt;this one&lt;/a&gt; for future aerospace engineers to decide which airfoil best suits their purpose. The question as to &lt;em&gt;why&lt;/em&gt; the pressure happens to be lower on the top compared to the bottom of the wing is not really that important. Heaps of empirical data show that it is the observed phenomena, and we work with it from there, as unsatisfying as that may be. &lt;/p&gt;&#xA;" OwnerUserId="144" LastActivityDate="2014-08-23T09:54:20.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8301" PostTypeId="2" ParentId="8288" CreationDate="2014-08-23T09:54:25.077" Score="5" Body="&lt;p&gt;That format is the flight id. The first three characters are the ICAO operator code which identifies the airline. The rest of the characters are unique to that flight. The first character after the ICAO operator code is always a number, after that both numbers and letters are allowed. The maximum length of the flight id is 7 characters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight id is transmitted to Mode S radars by the transponder and also broadcast on ADS-B. It is used to correlate a flight to a flightplan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight id is also the basis for the callsign used in radio communications. The ICAO three letter code represents the airline's callsign, the rest of the code is pronounced in the ICAO alphabet.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1961" LastEditDate="2014-08-23T11:48:50.407" LastActivityDate="2014-08-23T11:48:50.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8302" PostTypeId="2" ParentId="8259" CreationDate="2014-08-23T20:01:20.993" Score="4" Body="&lt;p&gt;Very few end up in a career as firefighter training objects.&lt;/p&gt;&#xA;" OwnerUserId="2327" LastActivityDate="2014-08-23T20:01:20.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8303" PostTypeId="1" AcceptedAnswerId="8369" CreationDate="2014-08-23T20:02:27.527" Score="8" ViewCount="1400" Body="&lt;p&gt;Reading an answer to &lt;a href=&quot;https://travel.stackexchange.com/questions/19651/are-there-any-advantages-to-boarding-a-flight-near-the-end-of-the-boarding-proce&quot;&gt;this question&lt;/a&gt; piqued my curiosity. Has there ever been an instance of an airliner's landing gear collapsing while loading/unloading passengers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not include after emergency landings, but just while &quot;sitting at the gate.&quot;&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2014-08-27T20:23:01.793" Title="Have landing gear collapsed at the gate?" Tags="&lt;airliner&gt;&lt;landing-gear&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8304" PostTypeId="2" ParentId="8303" CreationDate="2014-08-23T22:00:36.590" Score="4" Body="&lt;p&gt;Not so much in Airliners, but I have seen the result with a GA Aircraft when the pilot was demonstrating to a student (type endorsement) how the squat switch works. Well, squat switch wasn't working, and the gear retracted.. Not pretty..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, a squat switch is attached the the landing gear, and detects when there is pressure on the landing gear (as if there is pressure on the gear, it must be on the ground). If the switch detects pressure, the gear won't retract regardless of the Gear Selector position.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2014-08-23T22:00:36.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8305" PostTypeId="2" ParentId="8303" CreationDate="2014-08-24T05:23:00.630" Score="5" Body="&lt;p&gt;A good landing gear design locks it into the extended position under the aircraft's weight. This makes it physically impossible to retract it at the gate, but when the switch is in the wrong position the gear starts to retract during liftoff, when the wings take over the duty of carrying the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't mean that careless operation or maintenance procedures can't make it retract, however. When the aircraft is poorly balanced, say during loading and unloading, the weight on the nose gear might not suffice to lock it, so a wrong switch position can cause an unintended retraction.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-27T12:37:27.210" LastActivityDate="2014-08-27T12:37:27.210" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8306" PostTypeId="1" AcceptedAnswerId="8307" CreationDate="2014-08-24T06:46:41.890" Score="13" ViewCount="8744" Body="&lt;p&gt;Wrist watches usually use the barometric pressure sensors they have to calculate the altitude. I have also confirmed this from the manual of my watch, which states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The watch displays altitude values based on air pressure readings taken by a built-in pressure sensor.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Fine that's understood and makes sense and has always worked for me wherever I go. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then how does it know altitude during flight? The cabin of all commercial airliners are pressurized and hence the air pressure is not changing inside the cabin with the change in altitude (as happens for descent or ascent on ground). I know that even the aircraft itself uses pressure sensors for many calculations but those sensors are mostly usually on the Pitot tube and they sense the real outside pressure and not inside an pressurized cabin&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also like to mention that yes the altitude reading it takes during a flight is not always close to what the real value is but still it does track the altitude difference when pressure inside the cabin remains same, how so?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Please note&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That I didn't include the exact details of my watch because neither am I promoting any special model or a brand nor am I asking specifics of how a watch works, focus is on air pressure inside the cabin, not on watch. If needed I can provide the model and manual reference links. &lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="1048" LastEditDate="2014-08-24T06:51:52.957" LastActivityDate="2015-10-21T21:59:22.740" Title="How does my Casio watch know the altitude in flight?" Tags="&lt;airliner&gt;&lt;cabin-pressure&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8307" PostTypeId="2" ParentId="8306" CreationDate="2014-08-24T07:04:46.490" Score="29" Body="&lt;p&gt;The pressure in the cabin does not remain the same. It decreases, but much more slowly, in such a manner that when the aircraft is at 37000 feet the pressure in the cockpit is the equivalent of 7000 or 8000 feet. Keeping the cabin pressure at sea level would pose incredible stress on the fuselage, due to huge difference in pressure between the inside and the outside.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-08-24T07:04:46.490" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8308" PostTypeId="1" AcceptedAnswerId="8309" CreationDate="2014-08-24T07:51:01.707" Score="9" ViewCount="3950" Body="&lt;p&gt;In order to allow adaption to changed pressure, the pressure change in an aircraft cabin is stretched out over time. My observation is that the cabin pressure drops even before the plane takes off, and has not yet reached ground level at the time the aircraft lands. This would make sense, allowing for longer adaption times, but needs better sealing which is able to work both ways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question to the systems specialists: Can an aircraft cabin have a lower pressure than outside, and is the technique of stretching out the pressure change as explained above actually used?&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-03-11T23:27:43.457" Title="Can cabin pressure be lower than outside pressure?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;cabin-pressure&gt;&lt;aircraft-systems&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8309" PostTypeId="2" ParentId="8308" CreationDate="2014-08-24T11:01:44.130" Score="11" Body="&lt;p&gt;Besides the sealing the aircraft would also need a vacuum pump that is able to pull air out of the cabin which means extra weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1974/how-is-the-cabin-pressure-maintained-inside-aircraft?rq=1&quot;&gt;The way aircraft maintain cabin pressure&lt;/a&gt; is through a air cycle machine that pushes air into the aircraft and outflow valves. There is no facility to pull air out of the craft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any pressure drop you may experience on the ground is probably because the pilot increases air pressure on the ground slightly to test the seals and then releases it before takeoff.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-08-24T11:01:44.130" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8310" PostTypeId="1" CreationDate="2014-08-24T11:29:18.527" Score="23" ViewCount="1734" Body="&lt;p&gt;Given the histories of flight data recorders and cockpit voice recorders, I somewhat understand their origins as two separate physical devices. Given their separate tracks of development, regulatory requirements, and storage mechanisms, it stands to reason that they historically existed as two separate &quot;things&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I'm under the impression that the vast majority of the commercial airliners operating today are utilizing solid state memory to store both flight data and cockpit voice recordings. Both devices share many similar requirements in regards to being capable of withstanding extreme heat, g-forces, impact resistance, submersion in water, etc. Both devices are equipped with underwater locator beacons. Even the bright orange color of both recorders are the same!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_recorder&quot;&gt;Wikipedia article&lt;/a&gt; on flight recorders briefly mentions that &quot;the FDR and CVR can be manufactured in one fireproof, shock proof, and waterproof container as a combined digital Cockpit Voice and Data Recorder (CVDR)&quot;. However, whenever I read about modern aviation accident investigations--1990s, 2000s, 2010s--investigators are always searching for and analyzing the two separate black boxes. I don't think I've ever heard of an accident that involved a single combined black box, so their usage still doesn't appear to be very widespread.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not? Since the only thing I can see that distinguishes a modern CVR from a modern FDR is the &lt;em&gt;type&lt;/em&gt; of data being stored, why didn't the integration of these separate devices become the norm decades ago? The best explanation I can come up with is some sort of notion of redundancy, but this doesn't make sense if they're storing two separate sets of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if a single combined recorder was deemed to be too risky, how hard could it be to just record &lt;em&gt;both&lt;/em&gt; sets of data on two identical recorders? At least that way, there's true redundancy being maintained. The fact that &quot;flight data&quot; and &quot;cockpit voice&quot; data are still being stored on two separate physical devices seems rather absurd in this day and age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems about as logical as buying and maintaining two separate external hard drives--one for my music collection, one for my movie collection. It'd be closer to life in the early 90s, when I had a collection of VHS tapes and a collection of cassettes. But now that everything is digital, it makes sense (logically and financially) to just use one device to store both collections. Why isn't it the same with modern-day FDRs and CVRs?&lt;/p&gt;&#xA;" OwnerUserId="3311" LastActivityDate="2018-01-20T16:47:26.910" Title="Why are FDRs and CVRs still two separate physical devices?" Tags="&lt;accidents&gt;&lt;flight-data-recorder&gt;&lt;avionics&gt;&lt;cockpit-voice-recorder&gt;&lt;accident-investigation&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8311" PostTypeId="2" ParentId="8310" CreationDate="2014-08-24T12:16:50.267" Score="20" Body="&lt;p&gt;You probably wouldn't believe the effort needed to certify anything that flies on an aircraft. This is a multi-year process, especially if it is so much security-related as the CVR and FDR. And it needs to be done with all national authorities of your intended customers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a case of good-enough. The advantage from combining both is real, but so small, that nobody so far thought it worthwhile to go through the certification process. And regarding redundancy, transmitting the recorded data to some ground station would be even better than recording twice on the same aircraft. If that would have been installed in &lt;a href=&quot;http://avherald.com/h?article=4710c69b/035&amp;amp;opt=4096&quot;&gt;MH370&lt;/a&gt;, most of the search effort could have been saved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect something to happen with the transmitting of data, and then both devices could conceivably merged into one.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-08-24T12:16:50.267" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8312" PostTypeId="1" AcceptedAnswerId="8353" CreationDate="2014-08-24T15:11:40.727" Score="8" ViewCount="1567" Body="&lt;p&gt;What is the maximum altitude I'm allowed to fly a model plane or 'copter in Germany?&lt;/p&gt;&#xA;" OwnerUserId="3314" LastEditorUserId="72" LastEditDate="2014-08-27T10:14:34.797" LastActivityDate="2017-02-21T11:27:29.463" Title="What is the maximum altitude allowed to fly a model plane/copter in Germany?" Tags="&lt;germany&gt;&lt;altitude&gt;&lt;model-aircraft&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8313" PostTypeId="2" ParentId="8308" CreationDate="2014-08-24T23:17:12.030" Score="2" Body="&lt;p&gt;No aircraft is capable of reducing pressure below ambient - that would require pumps going the other way, and there's zero reasons to do it. Your observation of the cabin pressure dropping is an illusion, probably the pressure increasing a small amount as the pressurization system comes online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is conceivable that an aircraft could have a negative pressure differential on descent. If it descends very quickly it could have in internal pressure of 8,000 feet (normal cruise pressure) but be below that altitude. The difference would not last long, but it does take time to pump up a widebody - a fully pressurized 747 holds an extra ton of air, engines are at idle and the outflow valve (inflow in this case) isn't all that big.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-08-25T03:58:46.417" LastActivityDate="2014-08-25T03:58:46.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8314" PostTypeId="2" ParentId="8308" CreationDate="2014-08-25T00:12:01.717" Score="1" Body="&lt;p&gt;To my knowledge there is no aircraft that has the equipment to purposely create a lower pressure inside the cabin.  However, as previously mentioned, it is possible to descend at a rate that results in a lower pressure inside the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the T-38 we will actually RAM DUMP before opening the canopies for this exact reason.  The pressurization schedule is such we are at ambient pressure until reaching 8000' before it begins to pressurize to stay at a cabin altitude of 8000' until 23000'.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2014-08-25T00:12:01.717" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8316" PostTypeId="1" AcceptedAnswerId="8317" CreationDate="2014-08-25T09:01:02.863" Score="16" ViewCount="34205" Body="&lt;p&gt;I want to build a quadcopter but don't have any idea about motor and rotor size selection.&#xA;Is there a formula or equation to use? What are other things that need to be considered? Trial and error method would be waste of time and money.&lt;/p&gt;&#xA;" OwnerUserId="3302" LastEditorUserId="3302" LastEditDate="2018-08-15T06:41:20.083" LastActivityDate="2018-11-27T13:00:34.820" Title="How to calculate the required motor power and rotor size with respect to the weight of quadcopter?" Tags="&lt;aircraft-design&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8317" PostTypeId="2" ParentId="8316" CreationDate="2014-08-25T11:17:17.750" Score="19" Body="&lt;p&gt;The most important thing to remember here is the Purpose. &lt;strong&gt;&lt;em&gt;For what purpose do you want to use the Quadcopter&lt;/em&gt;&lt;/strong&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said , let’s start with the very basic .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Required Thrust = ( Weight x 2 ) / 4&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to choose a motor  you need to determine how much weight you are planning to take, and then work out the thrust required to lift the quadcopter .Also , when purchasing motors  you need to consider Watt’s and Efficiency as well apart from Motor KV and Thrust.The higher the Efficiency, the better it is.The manufacturer/seller of Motors will provide the specifications about the Motor. This will help you to find out the thrust,power, rpm etc of the motor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/__28675__D2830_11_1000kv_Brushless_Motor_UK_Warehouse_.html?strSearch=1000kv&quot;&gt;http://www.hobbyking.com/hobbyking/store/__28675__D2830_11_1000kv_Brushless_Motor_UK_Warehouse_.html?strSearch=1000kv&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quadcopters have 2 clockwise(CW) and 2 counter-clockwise(CCW) propellers and it has two flight configurations. X config and + config. In X config two arms will face front side while in + config only one arm will face front side. If you are making Quadcopter with plus config you can tune your quadcopter easily by  single axis tuning method .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=sfAkXe8IBVo&quot;&gt;Single Axis PID Tuning A Quadcopter&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Increased propeller pitch and length generally  draws  more current. Also the pitch can be defined as the travel distance of one single prop rotation. In other words, higher pitch means slower rotation, but will increase your vehicle speed which in turn will use more power.If your intention is to do acrobatics, you will need torque propellers which provide more acceleration and it puts less pressure on the power system. Lower pitch propellers will also improve stability.A higher pitch propeller moves greater amount of air, which could create turbulence and cause the aircraft to wobble during hovering. If you notice this with your quadcopter, try to choosing a lower pitched propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://blog.oscarliang.net/how-to-choose-motor-and-propeller-for-quadcopter/&quot;&gt;http://blog.oscarliang.net/how-to-choose-motor-and-propeller-for-quadcopter/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also choose to use this below &lt;strong&gt;Quadcopter Calculator&lt;/strong&gt;. You can dial in everything from motors to props to ESC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecalc.ch/indexcalc.htm&quot;&gt;http://www.ecalc.ch/indexcalc.htm&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-08-25T11:17:17.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8318" PostTypeId="1" CreationDate="2014-08-25T12:56:36.260" Score="30" ViewCount="13324" Body="&lt;p&gt;I live in the UK and would like to learn flying jets, but most courses seem to start with propeller planes.&#xA;Not sure if this might be a misconception about the safety of different aircraft types, but I remember having read or heard somewhere that small propeller planes are, well, less safe than jets; maybe because they are more fragile and less powerful than jets when it comes to bad weather and are also difficult to recover from dangerous situations... not sure and cannot find the reference for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But also doing a quick search for popular aircraft types, the propellers like Cessna seem to have huge numbers of crashes/incidents compared to jet engine aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is - why are propeller planes favored in training e.g. for the Private Pilot License? Is it simply because they are cheaper and wouldn't be such a huge loss of they crash?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any alternatives where I could start with a jet engine?&lt;/p&gt;&#xA;" OwnerUserId="3321" LastActivityDate="2021-03-25T22:12:35.943" Title="Why does flight training usually start with (unsafe?) propeller planes and not with (safer?) jets?" Tags="&lt;flight-training&gt;&lt;propeller&gt;&lt;jet&gt;" AnswerCount="12" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8319" PostTypeId="2" ParentId="8318" CreationDate="2014-08-25T13:13:42.407" Score="48" Body="&lt;p&gt;In the hands of an inexperienced pilot, a jet is definitely the unsafer choice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the general higher speeds, there is less time to recover from errors and they require more anticipation to be ahead of the game. Small errors will grow into large errors in relatively short time. In slower aircraft there is more time to correct. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, jet and turbine engines have slower response times than piston engines, which is important when you need to abort a landing for example. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that there are more accident and incidents with propeller aircraft is telling little about the inherent safety of these aircraft, instead it says something about the relative inexperienced pilots that often operate them. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2019-05-01T20:54:11.727" LastActivityDate="2019-05-01T20:54:11.727" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8320" PostTypeId="2" ParentId="8318" CreationDate="2014-08-25T13:17:02.240" Score="59" Body="&lt;p&gt;Light Propeller Aircraft, if flown within their design limits, are just as safe as jets. If you do a proper and thorough daily inspection, you are far less likely to suffer any form of mechanical failure in the air. In saying this, the majority of all crashes, be it in a Jet Powered Airliner or a Propeller Driven Light Aircraft are caused due to pilot error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You start out learning in a light single as:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;They are lighter, and slower and can usually take the beating handed out by inexperienced pilots, this being:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hard landings&lt;/li&gt;&#xA;&lt;li&gt;Slipping onto the runway&lt;/li&gt;&#xA;&lt;li&gt;Just hammering the day lights out of the engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet Aircraft are extremely expensive, and generally fairly heavy. Inexperienced pilots generally pay AU$80,000 for a Commercial Pilot License (In Australia) which qualifies you to fly single engine aircraft not over 5,700kg under the VFR by day. This is an absolute, level entry qualification looking for a job (most people will find that they at least also need a night VFR rating or a MECIR), so to add the cost of doing training in a jet on top of that, even if it is just for PPL, will be massive.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet Aircraft will be insured to be flown by pilots who have an amount of total experience and experience on aircraft/engine type. So, again, unless you're willing to pay the massive excess and premiums to be put on the insurance, you're going to have to fly a prop.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now, you have identified that a lot of crashes are light singles (i.e. Cessna). This is because generally, these aircraft are not flown with the same discipline as a Jet Aircraft. Also, the pilots flying them are generally lower hour pilots who do not have as much experience (again, this is a generalisation, not an exact figure of the total community).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for starting in a Jet, I honestly doubt that there is any flight school on the planet that will allow you to start training in a Jet (Even Fighter Jet pilots start out flying tiny little single engine aircraft).&lt;/p&gt;&#xA;" OwnerUserId="3223" LastEditorUserId="65" LastEditDate="2014-08-25T17:58:21.093" LastActivityDate="2014-08-25T17:58:21.093" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8321" PostTypeId="2" ParentId="8308" CreationDate="2014-08-25T13:19:28.287" Score="5" Body="&lt;p&gt;The A320 family as well as the B737NG series of aircraft start to pressurize during the takeoff roll. The cabin pressure is increased by about 0.1 Psi as this makes pressure changes on the outflow valve during the roll and the rotation less noticeable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only during a descent with the outflow valve closed, the cabin pressure could become lower than the ambient pressure. To prevent damage due excessive under pressure aircraft are fitted with inflow valves that open automatically if the pressure differential exceeds a threshold. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-08-25T13:19:28.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8322" PostTypeId="1" AcceptedAnswerId="8323" CreationDate="2014-08-25T13:51:18.610" Score="21" ViewCount="26269" Body="&lt;p&gt;If telephones/smartphones/tablets are not allowed on planes, how comes when you buy duty free items from the cabin crew and pay by cc they will use the card reader?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that in order to remove credit there must be some sort of connection to the various credit cards circuits in real time in order to achieve this?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-03-12T19:19:05.773" LastActivityDate="2016-11-15T14:15:33.730" Title="How are credit cards processed during flight?" Tags="&lt;security&gt;&lt;cell-phone&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8323" PostTypeId="2" ParentId="8322" CreationDate="2014-08-25T14:03:52.597" Score="24" Body="&lt;p&gt;It will either go through the airline's existing air-to-ground system (like the seat-back phones you pay $5/min for) or they've got a store-and-process-later arrangement with the card companies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Just because you can't use a phone doesn't mean the airline can't, they just follow certain conditions better)&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-08-25T14:03:52.597" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8324" PostTypeId="2" ParentId="8322" CreationDate="2014-08-25T14:04:24.003" Score="31" Body="&lt;p&gt;Presumably, they use an off-line transaction. The reason your credit card has raised numbers is that, in the old days, before ubiquitous data connections, a card transactions used a machine like this&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8ZOsD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;to transfer an imprint of your card details onto a form, using carbon paper. You would then sign the form and the merchant would send it off to the bank to get paid. It wasn't possible to verify in advance that you had enough money in your account but the deal was that the bank would honour the transaction and then come after you with a big stick.  The point of my mentioning this is that, although we're now very used to the idea that the merchant talks to your bank while you make a card transaction, this wasn't the case even 20 years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, it's still possible to make a card transaction without verifying in advance that the card has sufficient funds, so that you can still buy stuff on your card even if the merchant's phone line or internet is broken. In fact, the last-case fall-back is to go back to the swipe machines and carbon paper.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-08-25T14:04:24.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8325" PostTypeId="2" ParentId="8318" CreationDate="2014-08-25T14:41:18.863" Score="21" Body="&lt;p&gt;Small propeller aircraft have more incidents and accidents, because they can be flown by single pilot and that pilot is often not very experienced (&lt;a href=&quot;http://en.wikipedia.org/wiki/Private_pilot_license&quot;&gt;PPL&lt;/a&gt; requires only 40 hours in US and 45 in Europe), while anything transport category requires two pilots and the pilot in command has to have &lt;a href=&quot;http://en.wikipedia.org/wiki/Airline_Transport_Pilot_Licence&quot;&gt;ATPL&lt;/a&gt; and for that they need to have 1500 hours experience (yearly limit is 1000 hours). Note that transport category propeller aircraft like ATR-42/72 or Dash-8 don't have significantly higher accident rate compared to transport jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If flown by experienced pilots, a &lt;em&gt;single engine&lt;/em&gt; plane is slightly less safe, because if the engine quits it has to do emergency landing and it may not always be possible over rough terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand though, propeller planes are slower (propellers are efficient at slow speeds, jets only at high speeds) and easier to handle because jet engines react slowly to power changes. And smaller aircraft has less inertia, so it reacts to control inputs more readily too. Therefore you want to start with a small propeller aircraft in which mistakes can be more easily fixed, build up some experience with the general behaviour and only then progress to the faster and larger jets that require gentler handling and more thinking in advance.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-08-25T14:41:18.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8326" PostTypeId="2" ParentId="8322" CreationDate="2014-08-25T14:42:18.437" Score="23" Body="&lt;h2&gt;What is it called?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Buying stuff on an airplane during flight is know is &lt;em&gt;in-flight commerce (IFC)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;How it works?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Credit cards are swiped via wireless handhelds on aircraft but the transactions are processed when the aircraft gets on the ground.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Limitations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Because of this billing mechanism – which sometimes results in fraudulent transactions – there is a ceiling of the value of items that can be comfortably sold today.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Read more &lt;a href=&quot;http://blog.unibulmerchantservices.com/general-requirements-for-in-flight-commerce-terminals/&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.flightglobal.com/blogs/runway-girl/2009/03/real-time-in-flight-credit-car/&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-08-25T14:42:18.437" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8327" PostTypeId="2" ParentId="8318" CreationDate="2014-08-25T15:05:20.147" Score="19" Body="&lt;p&gt;Small piston airplanes are &quot;cheap&quot; (as airplanes go) to operate and jets are an order of magnitude more expensive.  For example, you can find small piston trainers on the order of \$100/hour to operate whereas a jet is often well north of \$1000/hr to operate.  If your wallet can accept this, this is just one barrier to starting training in a jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small piston training airplanes are everywhere.  Go down to your nearest airport and you'll probably find a few.  Jet airplanes for training for the most part just do not exist.  The vast majority of jet training happens in simulators, and these simulator courses are really only designed to provide type ratings and possibly ATP ratings, not primary training.  This means you'll probably have to buy or lease a jet.  This will be &lt;em&gt;very&lt;/em&gt; expensive.  This is your biggest barrier to starting training in a jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you own or rent a jet, you want to insure it.  I sincerely doubt you'll find anyone willing to underwrite hull loss insurance on a jet used for primary training of an unrated pilot. Perhaps you could find coverage for a premium equal to the full replacement cost of the jet, but that really isn't practical.  This is a barrier to training, but if you can afford to do this you might not care that you can't find insurance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking of type ratings, it is very likely you are going to need one of those to operate the jet, this will complicate your training and checkride because type ratings are tested to ATP standards, which means you will be required to fly to a higher standard with tighter tolerances than you would otherwise be requires at this stage of your training.  You'll also be crippled without an instrument rating because you can't fly the jet above 18,000 feet (USA) without one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking of checkrides, you'll need to find an examiner that is typed in the jet you are using and who can conduct the checkride.  Easier said than done.  A typical jet isn't really suited to the private checkride either.  The required cross country navigating with a map and the required diversion would be a lot of work in a very fast and complex airplane for a brand new pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before you can go on a checkride, you need training.  You need a CFI who is typed in the jet and that CFI is going to be more expensive than the CFI you would be using in the piston airplane.  Probably much more expensive.   You will probably also need to spend much more time with the instructor than you would in the piston airplane because the jet moves much faster and you will be flying to ATP standards instead of private pilot standards.  More practice == more money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to be in a jet ASAP and you can afford to own one and insure it, your best bet is to just do the private in a piston airplane then do an instrument rating in a piston airplane, do your multi-engine rating in a piston airplane, and then get a type rating in the jet to transition into flying the jet.  You'll probably also need to hire a typed pilot to fly with you (for insurance costs) until you build a significant amount of time in the jet.  If you didn't buy a jet capable of single pilot ops, then you'll need to hire a pilot because the plane requires two pilots anyway, but the entirety of my post assumes you picked a single pilot capable jet.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-08-25T15:05:20.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8329" PostTypeId="1" AcceptedAnswerId="8334" CreationDate="2014-08-25T17:23:53.607" Score="6" ViewCount="32255" Body="&lt;p&gt;I'm not sure if this is the right place to ask this question, and I'm sure that some of the answers will depend on the country, so I apologise if this is &quot;too local&quot; or &quot;off topic&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm considering getting a Private Pilot's License. Ideally it will be for both recreational use and also to make money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read that there are some limitations on how you can make money as a Pilot with only a PPL. But some of the things I've read a pretty vague and open to interpretation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of jobs/careers can you get with a PPL?&lt;/p&gt;&#xA;" OwnerUserId="3289" LastEditorUserId="572" LastEditDate="2015-02-19T09:02:14.960" LastActivityDate="2015-02-19T09:02:14.960" Title="What careers are available for someone with a PPL?" Tags="&lt;ppl&gt;&lt;casa-regulations&gt;&lt;australia&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8330" PostTypeId="2" ParentId="8329" CreationDate="2014-08-25T17:33:52.860" Score="7" Body="&lt;p&gt;If you are talking about Europe (EASA) &lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1408514789765&amp;amp;uri=CELEX:02011R1178-20140403&quot; rel=&quot;noreferrer&quot;&gt;Doc 1178&lt;/a&gt; states at PPL privileges:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;a) The privileges of the holder of a PPL(A) are to act without remuneration as PIC or co-pilot on aeroplanes or TMGs engaged in non-commercial operations.&lt;/p&gt;&#xA;&lt;p&gt;(b) Notwithstanding the paragraph above, the holder of a PPL(A) with instructor or examiner privileges may receive remuneration for:&lt;/p&gt;&#xA;&lt;p&gt;(1) the provision of flight instruction for the LAPL(A) or PPL(A);&lt;/p&gt;&#xA;&lt;p&gt;(2) the conduct of skill tests and proficiency checks for these licences;&lt;/p&gt;&#xA;&lt;p&gt;(3) the training, testing and checking for the ratings or certificates attached to this licence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Bottom line you could make money with PPL by being a flight instructor or a flight examiner. A side effect would be also accumulation of flight hours that would permit you to continue with a course for commercial pilot.&lt;/p&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-25T17:33:52.860" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8331" PostTypeId="2" ParentId="8289" CreationDate="2014-08-25T18:11:20.743" Score="2" Body="&lt;p&gt;3000 fpm is considered normal at one company that I worked for.  Obviously, we can deviate within reason.  I have routinely descended at more than 3000fpm in non-emergency situations.  Aggressive stepdowns on a STAR, controller requests expedited descent for traffic, slam dunk from 10,000ft+ (cleared for visual, hand off to tower, immediately cleared to land), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, 3000fpm was set as normal as per GOM for a reason; passenger comfort.&lt;/p&gt;&#xA;" OwnerUserId="835" LastActivityDate="2014-08-25T18:11:20.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8332" PostTypeId="2" ParentId="8318" CreationDate="2014-08-25T18:41:23.957" Score="10" Body="&lt;p&gt;There are a lot of good answers here already that cover some of the most important answers: the extreme cost difference, jet engines respond slower, very low availability of training equipment and flight instructors, inability to (legally) fly the jet at the altitude it's designed to fly at (since you need an instrument rating to enter Class A airspace, which is everything above 18,000 ft in the U.S.,) etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, another important thing to note is that you can practice maneuvers in a small, single-engine aircraft that simply aren't practical to practice in most jets. In a PA-28, it's no big deal to practice stalls and stall recovery (which is a required skill for a private pilot certificate.) Practicing stalls in a Learjet, let alone a 737, is quite another story. Same for 60 degree banks, slow flight, etc. These are things that all pilots need to practice, but which just aren't practical (or safe) to practice in most jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for jets being 'safer,' as others have said, the safety record of light aircraft is more related to the average skill level of the pilots usually flying them versus the average skill level of the pilots usually flying jets. An airline pilot will have thousands of hours of flight time. Many accidents in small, single-engine aircraft, on the other hand, are from low-hour pilots and even student pilots. A student pilot flying a jet will be decidedly unsafe. Student pilots are much safer when flying small, light, and (relatively) slow aircraft that are also not nearly as complicated to operate. The light aircraft are much more forgiving to the mistakes that student pilots make than jets will be.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2014-09-03T20:14:47.823" LastActivityDate="2014-09-03T20:14:47.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8333" PostTypeId="2" ParentId="8329" CreationDate="2014-08-25T18:52:23.823" Score="6" Body="&lt;p&gt;For the U.S., career options for someone with a private pilot certificate can be summed up as &quot;stuff that doesn't involve flying an aircraft.&quot; It is illegal to be paid for your services as a pilot in the U.S. without a commercial pilot certificate. The flight instruction exemption mentioned above for Europe does not apply in the U.S. All CFIs in the U.S. are required to have a Commercial Pilot Certificate first. Also, for airplanes or other powered-lift aircraft, the CFI must also have an instrument rating in the U.S.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One exception to note is that private pilots in the U.S. may operate an aircraft for the furtherance of a business provided that they are not being paid for flying the aircraft. So, you could, for instance, fly yourself on a business trip if you have a PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source for CFI requirements: &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/45D3A3472DABA40886256EE10063B376?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.183&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2014-08-25T19:43:52.957" LastActivityDate="2014-08-25T19:43:52.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8334" PostTypeId="2" ParentId="8329" CreationDate="2014-08-25T20:50:10.430" Score="4" Body="&lt;p&gt;For Australia, you are extremely confined as to what you can do with a PPL to earn money. Skywriting &lt;a href=&quot;https://aviation.stackexchange.com/questions/8329/careers-available-for-someone-with-a-ppl#comment14706_8330&quot;&gt;as people have mentioned&lt;/a&gt;, will probably mean you lose your license here. What you can do according to &lt;a href=&quot;http://www.comlaw.gov.au/Details/F2014C00614/Html/Volume_1#_Toc386720342&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;CAR 2.7&quot;&gt;CAR 2.7&lt;/a&gt; (Civil Aviation Regulation) is essentially;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crop Dusting on a person's property using their aircraft (only on their property)&lt;br&gt;&#xA;(You would also require an Agricultural Rating for this)&lt;/li&gt;&#xA;&lt;li&gt;Transporting the owner of the aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, here's where you can work within the rules. According to the definition of the CAR, you can logically fly charter flights as private if you are transporting the owner of the aircraft. What if the aircraft is owned by a company? Logically, anyone who works for that company is considered an owner, or goods reasonable similar to property of the owner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, take everything I've said here, take with a grain of salt as I am not a CASA lawyer (Thank god), and as a disclaimer, nothing that I have said here can be taken as an exact interpretation of the law or anything reasonably similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, have a read of that CAR, and you will possibly find avenues to follow, or just bite the bullet, go to a VET Fee Help approved school and do your CPL?&lt;/p&gt;&#xA;" OwnerUserId="3223" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-08-26T02:12:44.980" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8335" PostTypeId="2" ParentId="8312" CreationDate="2014-08-26T01:30:46.550" Score="-1" Body="&lt;p&gt;Try this link: &lt;a href=&quot;http://www.rc-network.de/magazin/artikel_02/art_02-0001/art_02-0001-00.html#3&quot; rel=&quot;nofollow&quot;&gt;http://www.rc-network.de/magazin/artikel_02/art_02-0001/art_02-0001-00.html#3&lt;/a&gt;.  If you want an even broader view, go to this link here: &lt;a href=&quot;http://www.rc-network.de/magazin/artikel_02/art_02-0001/art_02-0001-00.html&quot; rel=&quot;nofollow&quot;&gt;http://www.rc-network.de/magazin/artikel_02/art_02-0001/art_02-0001-00.html&lt;/a&gt;.  Hope this helps!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a quote from the first link: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Basically, it can be stated that the model airplane at the latest at&#xA;  FL 100 (FL = flight level, flight level), which is about 3 km above&#xA;  sea level, comes to an end.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The page is in German, and of course, Chrome didn't provide a perfect translation.  So model airplanes aren't allowed to fly higher than 3 km.  Higher airspace is reserved for commercial flights, military, etc.&lt;/p&gt;&#xA;" OwnerUserId="3328" LastEditorUserId="19" LastEditDate="2014-08-26T05:43:34.753" LastActivityDate="2014-08-26T05:43:34.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8336" PostTypeId="2" ParentId="8289" CreationDate="2014-08-26T02:57:42.483" Score="12" Body="&lt;p&gt;Normal descent rates will vary by operator and by airframe, but in general they follow this logic:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Power at flight idle,&lt;/li&gt;&#xA;&lt;li&gt;Airspeed at or near max mach number or max KIAS,&lt;/li&gt;&#xA;&lt;li&gt;Spoilers stowed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Generally they wont push airspeed right up to the limits and incorporate a small margin, but this is general idea.  This is the most efficient descent because it means you stayed as high as long as possible but not so long you need to &quot;cheat&quot; with lift-destroying devices.  Whatever descent rate this configuration results in is the &quot;normal&quot; rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual descent rate will vary in practice.  ATC might descend you early, and then you will use a lower descent rate to stay higher longer (500 fpm unless they ask for more).  If they keep you high too long, you opt for a higher rate of descent (spoilers!).  The descent rate chosen will also be effected by the vertical wind profile.  You may have a strong headwind and since you are covering ground slower opt for a slower descent, but if that headwind reduces in strength that might end up biting you later.  Many descents are &quot;at pilot discretion&quot;, and thus we'll typically stay high as long as we can until we can descend at (or near) idle to meet our crossing restrictions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passenger comfort isn't directly correlated to descent rate.  Many pax will claim their ears popped more, but in reality the cabin pressure change is the same regardless of the descent rate.  Things the pax are sensitive to that do occur are accelerations, and how fast the airplane is pitched into the descent will have a large impact on how the descent rate is perceived in the cabin (This is the same reason a vertical deviation of 50 feet in turbulence makes passengers think they dropped 1000 ft, it is all in the acceleration).  Deck angle may also play a role in passenger perception.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-08-26T02:57:42.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8337" PostTypeId="1" AcceptedAnswerId="8338" CreationDate="2014-08-26T03:55:41.433" Score="9" ViewCount="1035" Body="&lt;p&gt;It seems like skywriting would be pretty difficult to learn, since there doesn't seem to be any way to step back and see if you made a mistake. And yet people have been doing it since the early days of flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here is my question: how does one go about learning to sky write, and are there any tools to make it easier (a ground mounted webcam with a panel mounted display was an idea that came to mind, have no idea how feasible that is)?&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-08-26T07:00:29.163" Title="How does one learn to sky write?" Tags="&lt;aerobatics&gt;&lt;airshow&gt;&lt;skywriting&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8338" PostTypeId="2" ParentId="8337" CreationDate="2014-08-26T04:30:37.180" Score="8" Body="&lt;p&gt;Try reading this &lt;a href=&quot;http://www.businessweek.com/articles/2012-08-14/odd-jobs-sky-writing-is-just-as-hard-as-you-think-it-is&quot;&gt;article from businessweek&lt;/a&gt;.  It's going to give you an answer, but you're probably not going to like it.  Here a quote: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“It requires an incredible level of precision flying,” Oliver says. “There are so many factors. Where’s the sun, which way is the wind blowing, where’s your crowd? You only learn that over time, after doing it enough. And you can’t go practice when skywriting fluid is 10 [dollars] a gallon and gasoline is 7 [dollars] a gallon.”&#xA;  It’s also difficult to learn the craft of skywriting when nobody is willing to teach it. Oliver and Asbury-Oliver won’t share any of their secrets. In fact, while Asbury-Oliver was employed by Pepsi, she was contractually forbidden from discussing her skywriting techniques with anybody, including friends, colleagues, and journalists. “In the ’30s and ’40s, there were a lot of skywriters trying to make a living,” she says. “So they shared nothing. They wouldn’t tell each other what kind of fluid they used to make the letters, what kind of exhaust pump they used. Everything was top secret.” While an air of secrecy might’ve made sense a century ago, why do they continue to be clandestine, despite their competition being essentially nonexistent? “We’re old enough and we’ve been around long enough that we’re both traditionalists,” says Oliver.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3328" LastEditorUserId="19" LastEditDate="2014-08-26T07:00:29.163" LastActivityDate="2014-08-26T07:00:29.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8339" PostTypeId="1" AcceptedAnswerId="8340" CreationDate="2014-08-26T09:22:40.467" Score="15" ViewCount="5499" Body="&lt;p&gt;One of the optional services in &lt;a href=&quot;http://www.rolls-royce.com/civil/services/totalcare/&quot;&gt;Rolls-Royce TotalCare&lt;/a&gt; is &quot;Engine Transportation&quot;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This service includes routine transportation of engines between the customer’s main base (or designated station) and the engine shop, and/or remote site transportation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Jet engines can be very large heavy and expensive items. How are they transported? Are they flown or do they use road transport? Are there dedicated vehicles?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="65" LastEditDate="2015-03-13T15:39:53.493" LastActivityDate="2020-11-07T06:26:17.197" Title="How are off-wing jet engines transported?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8340" PostTypeId="2" ParentId="8339" CreationDate="2014-08-26T09:33:50.450" Score="27" Body="&lt;p&gt;They have the usual transport options: shove into cargo area, on a flatbed truck, shipping container,...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can also be attached below the wing of a large aircraft and flown with if there is no room in the cargo area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/abnHA.jpg&quot; alt=&quot;enter image description here&quot;&gt;(stolen from &lt;a href=&quot;https://aviation.stackexchange.com/questions/6303/how-do-you-repair-a-grounded-aircraft-at-a-remote-location&quot;&gt;this question&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice the extra engine on the near wing.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-08-26T09:33:50.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8341" PostTypeId="2" ParentId="8339" CreationDate="2014-08-26T10:09:25.193" Score="18" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Conroy_Skymonster&quot; rel=&quot;nofollow noreferrer&quot;&gt;Conroy CL-44 &amp;quot;Skymonster&amp;quot;&lt;/a&gt; was built for the purpose of transporting three &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_RB211&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce RB-211&lt;/a&gt; engines. It was a derivative of the Canadair CL-44 and was meant to transport the engines for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_L-1011&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Tristar&lt;/a&gt;. Jack Conroy had before modified old C-97s to &lt;a href=&quot;http://www.allaboutguppys.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Super Guppy&lt;/a&gt; transporters, and those initially transported Saturn rocket stages for NASA.&lt;/p&gt;&#xA;&lt;p&gt;The picture below was shamelessly copied from the Wikipedia article. Note the bulges near the tail: They cover the hinges for the sideways opening fuselage.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/5QHFJ.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Today, Boeing 747 freighters can swallow most engines, so in the age of widebody transporters there is no more need for special aircraft for engine transport. For the ones that don't fit inside the 747, there is always the &lt;a href=&quot;https://www.youtube.com/watch?v=4PMJg-N0ICI&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antonov An-124&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-11-07T06:26:17.197" LastActivityDate="2020-11-07T06:26:17.197" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8342" PostTypeId="2" ParentId="8322" CreationDate="2014-08-26T11:24:42.330" Score="14" Body="&lt;p&gt;I worked with the credit card processing at one of the bigger airlines a few years ago. We used handhelds that stored the info from the magnetic strip of the card. The transactions were uploaded to our back office system and then to the payment service provider after the flight landed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only &quot;hard&quot; protection is the modulo 10 checksum of the credit card number (&lt;a href=&quot;http://en.wikipedia.org/wiki/Luhn_algorithm&quot;&gt;http://en.wikipedia.org/wiki/Luhn_algorithm&lt;/a&gt;). The fact that the airline knows exactly who is on a flight also makes it much harder to get away with this type of fraud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During my time at the company I don't think I heard of a single case of attempted credit card fraud (that doesn't mean there weren't any). I think theft is a much larger problem in on-board retail.&lt;/p&gt;&#xA;" OwnerUserId="3334" LastActivityDate="2014-08-26T11:24:42.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8343" PostTypeId="2" ParentId="8339" CreationDate="2014-08-26T12:41:43.767" Score="5" Body="&lt;p&gt;It's apparently pretty hard to get outer engine dimensions, but based on fan size and adding a bit, all but the largest engines will go on a standard truck. Oversize permits are readily available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls-Royce makes engines in Derby (amongst other places) but not at the airport. ( East Midlands airport has one runway, 8200 feet, which is a bit tight for a 747.) Therefore, engines must leave the factory by truck at least once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect that the decision to send the dud engine for service by truck, boat, on the wing or in the hold will be purely economics.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-08-26T12:41:43.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8344" PostTypeId="1" AcceptedAnswerId="8347" CreationDate="2014-08-26T12:50:48.170" Score="40" ViewCount="13232" Body="&lt;p&gt;A common theory from pro-Russian netizens surrounding the MH-17 tragedy is that it was a Ukrainian SU-25 ground attack fighter plane which shot down the civilian airliner. However, MH-17 was flying at 10,500m when the service ceiling of an SU-25 is 7,000m. They say that this discrepancy is made by the fact that the Ukrainian pilot used afterburners to get to the height MH-17 was flying at. Is this actually technically possible?&lt;/p&gt;&#xA;" OwnerUserId="3335" LastEditorUserId="1696" LastEditDate="2018-04-29T20:09:09.467" LastActivityDate="2018-04-29T20:09:09.467" Title="Is it possible for an SU-25 to fly high enough to shoot down a Boeing 777?" Tags="&lt;military&gt;&lt;aircraft-performance&gt;&lt;fighter&gt;&lt;jet&gt;&lt;altitude&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8345" PostTypeId="2" ParentId="8344" CreationDate="2014-08-26T13:57:01.010" Score="12" Body="&lt;p&gt;Parabolic trajectories above the service ceiling are possible. Just go up fast enough, and rely on inertia instead of lift to carry you upwards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, parabola's have the property that there's a long way up, a sharpish bend at the top, and a long way down again. That's not a practical way to intercept another aircraft, especially if your plane isn't designed to use off-board AA radar guidance to get the intercept course right (and a ground attack aircraft like the SU-25 wasn't designed like that at all - The Soviets had proper high-altitude interceptors for that)&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2014-08-26T13:57:01.010" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8346" PostTypeId="2" ParentId="8344" CreationDate="2014-08-26T13:59:18.160" Score="41" Body="&lt;p&gt;You're asking 4 things here:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Can aircraft fly higher than their stated service ceiling?&lt;/p&gt;&#xA;&lt;p&gt;Service ceiling can be exceeded, depending on the aircraft type, loadout, atmospheric conditions, and flight profile, but usually not very far or for very long.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does an SU-25 have afterburners?&lt;/p&gt;&#xA;&lt;p&gt;The SU-25 (NATO reporting name Frogfoot) has no afterburners, so that part of the claim is bonkers.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does an SU-25 have the capability to shoot down aircraft?&lt;/p&gt;&#xA;&lt;p&gt;It can carry light IR guided missiles for self defense, and of course has a gun, but would have no way to intercept an airliner at altitude, it doesn't have the endurance there nor the equipment to detect and track the aircraft (though in theory a ground controller could guide it of course).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Would an SU-25 be used for an intercept like that?&lt;/p&gt;&#xA;&lt;p&gt;Why should the Ukraine use an SU-25 ground attack aircraft when they have dedicated air defense fighters far more capable for the job?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;So no, the claim is utterly bonkers.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-26T19:35:05.783" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8347" PostTypeId="2" ParentId="8344" CreationDate="2014-08-26T14:02:01.793" Score="55" Body="&lt;p&gt;There is an excellent answer at &lt;a href=&quot;http://scottlocklin.wordpress.com/2014/07/21/can-the-su-25-intercept-and-shoot-down-a-777/&quot; rel=&quot;noreferrer&quot;&gt;http://scottlocklin.wordpress.com/2014/07/21/can-the-su-25-intercept-and-shoot-down-a-777/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-25&quot; rel=&quot;noreferrer&quot;&gt;SU-25&lt;/a&gt; is a ground attack fighter unsuited to intercepting and/or shooting down 777s. If the Ukrainian air force wanted to do so, they have better aircraft available. &lt;/li&gt;&#xA;&lt;li&gt;The SU-25 max speed is slower than a cruising 777.&lt;/li&gt;&#xA;&lt;li&gt;The SU-25 has an operational ceiling of 16000 ft with max weapons to 23000 ft clean, MH17 was at 33000 ft.&lt;/li&gt;&#xA;&lt;li&gt;It is an unpressurised aircraft.&lt;/li&gt;&#xA;&lt;li&gt;As a ground attack aircraft it probably only rarely carries air to air missiles. It can carry the R-60 infra-red air-to-air missile which has a 6 lb warhead effective against small aircraft. &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An R-60 once hit and destroyed one engine of a small BAE 125 business jet at 35000 ft but failed to bring it down, apparently the missile failed to explode.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_902&quot; rel=&quot;noreferrer&quot;&gt;KAL902&lt;/a&gt;, a Boeing 707, was hit by an R-60 and made an emergency landing 40 minutes later.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;The R-60 is a short-range missile (5 miles). The Russians claim the SU-25 came within two or three miles of MH17.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On the whole this makes the SU-25 a poor choice for shooting down a cruising 777. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems unlikely that a 777 would be shot down in this way. Not impossible, but far less likely than other proposed scenarios such as those involving BUK (SA-11) ground to air missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fHYR2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;Results of an &lt;a href=&quot;http://en.wikipedia.org/wiki/R-60_(missile)#Angola.2FCuba&quot; rel=&quot;noreferrer&quot;&gt;R-60 hitting a jet engine on a small business jet&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MUlyD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;Results of an &lt;a href=&quot;http://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_902&quot; rel=&quot;noreferrer&quot;&gt;R-60 hitting a Boeing 707&lt;/a&gt; ... two R-60s were launched, one missed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These R-60s were fired by supersonic interceptors, not by SU-25 ground-attack aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-27T14:31:13.217" LastActivityDate="2014-08-27T14:31:13.217" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="8348" PostTypeId="1" AcceptedAnswerId="8349" CreationDate="2014-08-26T14:47:54.910" Score="5" ViewCount="5881" Body="&lt;p&gt;I was part of a discussion about the differences between all engine climb gradients and one engine inoperative (OEI) climb gradients, and a colleague suggested that climb gradient can be calculated as &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$G = \frac{T-D}{W}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$G$ is Climb Gradient as a percent,&lt;/li&gt;&#xA;&lt;li&gt;$T$ is Thrust, &lt;/li&gt;&#xA;&lt;li&gt;$D$ is Drag, and &lt;/li&gt;&#xA;&lt;li&gt;$W$ is Weight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This derivation was never really explained, and it doesn't really make sense to me.  He continues by stating that lift can be assumed to equal weight for small climb angles, so that his equation becomes &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$G = \frac{T}{W} -\frac{D}{L}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $L$ is Lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some analyses, I can see using the approximation $W = L$, but since that is essentially assuming your climb gradient is 0, it doesn't seem prudent to use that assumption to calculate the climb gradient itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has anyone seen these equations before?  Or is there a piece to this that I'm missing that someone could explain to me?  &lt;/p&gt;&#xA;" OwnerUserId="3337" LastEditorUserId="19" LastEditDate="2015-02-18T19:58:31.900" LastActivityDate="2015-08-29T20:05:07.590" Title="How is the climb gradient calculated?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8349" PostTypeId="2" ParentId="8348" CreationDate="2014-08-26T15:03:21.410" Score="6" Body="&lt;p&gt;Assuming that thrust is entirely in the direction of travel and the flight path angle is constant, the Lift is equal to the weight times the cosine of the flight path angle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L = W\cos(\gamma)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small $\gamma$, $\cos(\gamma) \approx 1$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g. for a flight path angle of 10 degrees, the error introduced by the approximation is ~ 1.5%&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rXw78.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For unaccelerated climb, the sum of all forces in the along path direction cancel each other out:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ T-D-W\sin(\gamma) = 0$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gradient is $\tan (\gamma)$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, for small angles, $\sin(\gamma)\approx\tan(\gamma)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From there it is a small step to see that the calculation suggested by your colleague is acceptable for unaccelerated climbs at small flight path angles.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-08-29T20:05:07.590" LastActivityDate="2015-08-29T20:05:07.590" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8350" PostTypeId="2" ParentId="3915" CreationDate="2014-08-26T15:40:19.420" Score="3" Body="&lt;p&gt;I considered buying an airplane, I even came close but backed away because the particular airplane had some engine issues. In retrospect, it might have been cheaper to buy a plane at the start, but now I'm glad I didn't, primarily because the 150 I was looking at would not be a satisfying long-term airplane for my purposes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an advantage not mentioned in the previous answers, namely scheduling. Your airplane is always available (barring maintenance issues or instructor availability issues). However, the disadvantages, I think, outweigh the advantages. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If cost is one of the major factors for you, consider joining a flying club that is geared toward training. That's what I did. After an initiation fee, wet rental of our club 150s runs between 50 and 55 dollars (US) per hour. An added benefit is the social aspect of the club, it tends to reinforce the effort to finish getting your ticket. &lt;/p&gt;&#xA;" OwnerUserId="3211" LastActivityDate="2014-08-26T15:40:19.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8351" PostTypeId="2" ParentId="3915" CreationDate="2014-08-26T16:27:25.000" Score="3" Body="&lt;p&gt;The first thing I would do is put on paper for your benefit what the mission is.  Are you seeking a pilot career, or just want to fly for recreational purposes?  How many people will you be carrying on a regular basis? How far away are the destinations?  (Like from where you live to where your wife wants to go...  New York City to the Cape Cod area, in my case) and what kind of plane will carry the load you intend on carrying (kid stuff like strollers, playpens, and other...).  When all that is done, it will come close to defining the plane that is best for your needs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the big question:  Is that the plane you want to train in?  Is insurance affordable for a zero time student?  Can you find a CFI to instruct in that plane?  After you slam it on the ground for say 100 crash-and-go landings as you come up the learning curve, is that the plane you want to carry your family in? How difficult is it to find a flight instructor for that airplane?  If yes, do it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second big question, as mentioned above, how many hours per year do you anticipate flying?  It is pretty easy to calculate the annual flying bill if you are a renter.  Ownership will most likely be MORE expensive than that, because all of the fixed expenses are paid by you and not diversified among other renters.  If you have a bad annual inspection, as but one example: the renter can just walk away and find another plane/flight school.  The owner must pony up the repair costs or he is left with an unairworthy aircraft worth a fraction of the value in a sale.  One way or another you will pay for the repairs to get the plane back in annual.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So renting &lt;strong&gt;during training&lt;/strong&gt; may be cheaper and with less downside risk.  It will also allow you to clarify in your own mind what you want out of this flying thing, without the burden of ownership.  Owning brings the absolute freedom and joy of owning your own plane ... as well as the financial obligations of ownership.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, as noted above, most people use 100 hours of flying annually as the breakpoint between renting being better, and owning being better - but this will differ with each individual and each plane.  I wish you luck with the decision, and also with your training.  Come on up, the air is smooth and cool up here!  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-08-26T16:27:25.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8353" PostTypeId="2" ParentId="8312" CreationDate="2014-08-26T16:53:14.770" Score="6" Body="&lt;p&gt;The maximum altitude you can operate your RC plane or copter vertically without any clearance from ATC or another government body is the upper limit of class G airspace in Germany, which is the first available airspace from &lt;code&gt;GND&lt;/code&gt; to the lower vertical limit of controlled airspace C/D/E, which can be &lt;code&gt;2.500ft AGL&lt;/code&gt;&lt;sup&gt;1&lt;/sup&gt;, &lt;code&gt;1.700ft AGL&lt;/code&gt; or &lt;code&gt;1.000ft AGL&lt;/code&gt;, depending on surrounding airspace and airports in the vicinity. You can register at the website of the &lt;a href=&quot;http://www.dfs-ais.de&quot; rel=&quot;nofollow noreferrer&quot;&gt;DFS AIS&lt;/a&gt; to obtain the ICAO charts for your area and take a look at the airspace structure near you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual ceiling of airspace G can be significantly lower in the vicinity of larger airports, where the controlled airspace C/D/E has been lowered. The below picture shows how the dark green section around Frankfurt Airport has an airspace C with the vertical limits &lt;code&gt;1.500ft (MSL)/FL100&lt;/code&gt;. The airspace E in that area (not visible in this picture) has a vertical limit of &lt;code&gt;1.000ft AGL/C&lt;/code&gt;. Some areas within that section already have an elevation of &lt;code&gt;700-1100ft MSL&lt;/code&gt;, which leaves less than &lt;code&gt;100-400ft&lt;/code&gt; of airspace G before the overlying airspace C begins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tTro7.png&quot; alt=&quot;Airspace C around EDDF / Image Source: FL95.de&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to get your RC plane or copter into class C/D/E airspace, which is controlled airspace, you will need to obtain a clearance through the ATC unit in control of the sector or the FIS sector responsible, as postulated in &lt;a href=&quot;http://www.gesetze-im-internet.de/luftvo/__16.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;LuftVO §16a&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 16a LuftVO&#xA;  &lt;br&gt;Besondere Benutzung des kontrollierten Luftraums&#xA;  &lt;br&gt;&lt;br&gt;(1) Bei Inanspruchnahme des kontrollierten Luftraums ist von der zuständigen Flugverkehrskontrollstelle eine Flugverkehrskontrollfreigabe einzuholen für&#xA;  &lt;br&gt;&lt;br&gt;1. Fallschirmsprünge und den Abwurf von Gegenständen an Fallschirmen;&#xA;  &lt;br&gt;&lt;br&gt;&lt;strong&gt;&lt;em&gt;2. Aufstiege von Flugmodellen und anderen fern- oder ungesteuerten Flugkörpern mit Eigenantrieb;&lt;/em&gt;&lt;/strong&gt;&#xA;  &lt;br&gt;&lt;br&gt;3. Aufstiege von unbemannten Freiballonen mit einer Gesamtmasse von Ballonhülle und Ballast von mehr als 0,5 kg sowie Aufstiege von gebündelten unbemannten Freiballonen und Massenaufstiege von unbemannten Freiballonen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Please also mind &lt;a href=&quot;http://www.gesetze-im-internet.de/luftvo/__15a.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;LuftVO §15a&lt;/a&gt;, which dictactes that any RC plane or UAV needs to remain within the visbility range of the controller, so the maximum altitude can vary depending on the size of your RC plane or copter, the weather minima at your location and your own eyesight:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) Der Betrieb von unbemannten Luftfahrtsystemen ist verboten, wenn&#xA;  &lt;br&gt;&lt;br&gt;&#xA;  1. er außerhalb der Sichtweite des Steuerers erfolgt oder&lt;br&gt;&lt;br&gt;&#xA;  2. die Gesamtmasse des Geräts mehr als 25 Kilogramm beträgt.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: AGL = Above Ground Level&#xA;&lt;sup&gt;2&lt;/sup&gt;: MSL = Mean Sea Level&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2014-08-29T20:32:28.917" LastActivityDate="2014-08-29T20:32:28.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8354" PostTypeId="2" ParentId="8303" CreationDate="2014-08-26T19:18:40.810" Score="2" Body="&lt;p&gt;The guy in the hangar next to me had one of his friend's retract the gear on his beautifully restored P-40.  Luckily the mains did not retract, but the tailwheel did and bent quite a bit of metal.  Ouch!&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-08-26T19:18:40.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8355" PostTypeId="2" ParentId="8268" CreationDate="2014-08-26T20:26:11.930" Score="6" Body="&lt;p&gt;Assuming that one knows how engines work, one can explain it this way as well: Two spark plugs that fire simultaneously provide two spark locations that are physically apart from each other where the flame from each spark need to ignite only half of the charge so to speak or in other words the flame from each spark need to travel only half the distance (roughly) to complete its portion of the charge, where burning of the total charge is accomplished earlier in the down-stroke of the piston generating more work over the total piston stoke. Hope that is understandable as well. That also explains why late ignition timing reduces power. &lt;/p&gt;&#xA;" OwnerUserId="3339" LastActivityDate="2014-08-26T20:26:11.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8356" PostTypeId="1" CreationDate="2014-08-26T23:43:37.293" Score="1" ViewCount="1480" Body="&lt;p&gt;If an A/C have Radio failure ( sqk 7600 ) &#xA;How the ATC will give him instruction or how will he land ?!&lt;/p&gt;&#xA;" OwnerUserId="3319" LastActivityDate="2014-08-26T23:54:03.333" Title="If an A/C have Radio failure ( sqk 7600 ) How the ATC will give him instruction or how will he land?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ClosedDate="2014-08-27T03:56:18.957" ContentLicense="CC BY-SA 3.0" />
  <row Id="8357" PostTypeId="2" ParentId="8356" CreationDate="2014-08-26T23:54:03.333" Score="6" Body="&lt;p&gt;This is a question with many answers, depending on the conditions of the flight. Let me limit myself to private recreational aviation (what the FAA calls Part 91) in a single-engined propeller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying Visual Flight Rules (VFR), there are some airspaces you need to stay out of. For instance, US and Canadian Class B and C airspaces require radio communication. You won't be able to land at airports in such airspaces without some other arrangements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can give a signal that you are lacking radio communication. Squawking 7600 on your transponder is one way. Flying a triangular pattern, which might be visible to ATC on radar, is another way. I have sometimes used my cell phone to call ATC's phone number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Control towers in the US and Canada might well have &quot;light guns&quot;: bright spotlights which the controller can point at an aircraft, and colour red or green, and shine continuous or blinking light. A continuous green light from tower to an aircraft preparing to land means that aircraft is cleared to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying Instrument Flight Rules (IFR), there are specific procedures to follow if you are unable to communicate with ATC.  Frequently they boil down to holding for a few minutes, then continuing on your flight planned route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that some aircraft have no electrical system, let alone radios. They fly, take off, and land just fine. There are many airfields with no control towers. There is uncontrolled airspace in which to fly. In these cases, pilots maintain safety by seeing and avoiding other aircraft. Pilots fly traffic patterns before landing, and sequence themselves cooperatively.  Lots of aviation works just fine without radio communication between pilots and ATC.&lt;/p&gt;&#xA;" OwnerUserId="40" LastActivityDate="2014-08-26T23:54:03.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8358" PostTypeId="2" ParentId="3915" CreationDate="2014-08-27T06:49:24.253" Score="2" Body="&lt;p&gt;One more scenario to consider: You get a deal &quot;too good to refuse&quot;, and know it really is a good deal and you're not buying a lemon (maybe you can get a preferential selection from an auction of a bankrupt company, or from the estate of a deceased friend or relative).&lt;br/&gt;&#xA;That could potentially save you a bundle, more than the maintenance, taxes, and insurance you'd have to pay before you'd otherwise be willing and able to purchase an aircraft.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Of course there's also added risks involved, quite apart from the monetary side of it ending up more expensive than renting and buying later.&lt;br/&gt;&#xA;And that added risk is that you may for whatever reason end up having to abandon your dream of attaining your license and are now stuck with that aircraft that you may or may not be able to sell without a serious loss.&lt;br/&gt;&#xA;Think you get into a major car crash and lose an eye or leg, meaning you can't pass your medical. Or you get a heart condition with the same result. Maybe your financial situation becomes such (employer goes bankrupt, causing you to lose a lot of money, happens more often than you think) that you can't continue to pay for flying (if it's a choice of paying your aircraft dream or the rent or mortgage on your house, or to put food on the table...).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So weigh the risks carefully, don't get all glassy eyed seeing that glossy aircraft for sale at an airshow and sign for the thing before you consider what's in it for the future for you.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;One thing not yet mentioned I think is the option to set up a small company and register the aircraft to that, then using that company to rent it out to the flight school you're taking lessons from (or to a local flying club). That way the aircraft generates a bit of income, which you can then use to pay for its maintenance and insurance, with who knows maybe some left over to help pay for your flying lessons as well.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-27T06:49:24.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8359" PostTypeId="1" CreationDate="2014-08-27T09:09:19.637" Score="5" ViewCount="1230" Body="&lt;p&gt;Let's say I have an aircraft registration id (not sure about exact name) like &lt;code&gt;LN-DYO&lt;/code&gt;. Where can I find an information about configuration of the aircraft - i.e. number of first class seats, business class and economy class seats? I would like to have some automated solution (API? parsing of web-pages?) to get this data for a number of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2421" LastEditorUserId="7532" LastEditDate="2015-12-15T22:21:05.213" LastActivityDate="2015-12-15T22:21:05.213" Title="Where to find information about number of seats knowing the aircraft Registration ID?" Tags="&lt;aircraft-registration&gt;&lt;airlines&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8360" PostTypeId="2" ParentId="8359" CreationDate="2014-08-27T09:22:19.487" Score="7" Body="&lt;p&gt;The usual way would be to find out which airline operates that aircraft. Usually Google will give the answer. Otherwise &lt;a href=&quot;http://www.planespotters.net/search.php?q=LN-DYO&quot;&gt;planespotters.net&lt;/a&gt; will help. In this case it is Norwegian.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then &lt;a href=&quot;http://www.seatguru.com/airlines/Norwegian_Air_Shuttle/Norwegian_Air_Shuttle_Boeing_737-800.php&quot;&gt;seatguru&lt;/a&gt; will show you what the interior configuration is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know whether these website have public API's that could help you and I think that is a bit off topic for Aviation.SE.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-08-27T09:22:19.487" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8361" PostTypeId="1" AcceptedAnswerId="8371" CreationDate="2014-08-27T10:03:05.997" Score="9" ViewCount="1377" Body="&lt;p&gt;Has there ever been an instance of a crew having to 'bail out' during a test flight of a commercial style aircraft (I.e Airbus, Boeing etc)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that test flight crews often wear orange suits, parachutes during preliminary flight in case there is an issue.&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="19" LastEditDate="2017-01-25T16:12:22.267" LastActivityDate="2017-01-25T16:12:22.267" Title="Has there ever been a successful 'bail-out' during an airliner test flight?" Tags="&lt;accidents&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8362" PostTypeId="2" ParentId="8359" CreationDate="2014-08-27T12:56:00.857" Score="7" Body="&lt;p&gt;I seriously doubt there's any system that would have such information for a non-trivial number of aircraft.&lt;br/&gt;&#xA;Not only is the information pretty irrelevant except for the purpose of internal planning by the owner/operator of the aircraft (who obviously have it for their own aircraft in their internal systems), it's also liable to change suddenly.&lt;br/&gt;&#xA;For example Martinair flies (or flew, they may have retired them) several MD11 series aircraft that had palletised passenger cabins. These aircraft could, within a few hours, be converted between passenger and cargo configuration as needed (and I think could even be operated with partial passenger cabins). Such a source as you're looking for would never be able to reflect that.&lt;br/&gt;&#xA;Then there's the 747 Combi variants that used to be operated by KLM which had similar arrangements (but were permanently set up with only partial passenger cabins, an arrangement that could have been changed).&lt;br/&gt;&#xA;Aircraft may also go in for refurbishment and receive entirely new cabins with different layout. And that can happen without the aircraft being sold, just because the owner changes their business plan (e.g. they might reduce the number of business class seats on some aircraft because of reduced demand for them, sometimes even temporarilly, for example during the summer holiday season when business travel is slow).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So the source would need to get constant updates from people who have far better things to do than provide such updates, as they have no need whatsoever for the service that that source might provide.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-27T12:56:00.857" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8363" PostTypeId="1" CreationDate="2014-08-27T13:44:07.123" Score="4" ViewCount="627" Body="&lt;p&gt;I've heard that the Burning Man festival sets up a temporary airport each year for the week of the festival and that it is staffed by volunteers.  What is it like to be a volunteer there?  Do the employees at surrounding airports find dealing with them better or worse than non-volunteer airports?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: Previously I asked what it is like to be a &quot;volunteer ATC&quot;, but that is not the right terminology. I have broadened the question to be less specific.&lt;/p&gt;&#xA;" OwnerUserId="3346" LastEditorUserId="14957" LastEditDate="2016-10-19T18:12:41.687" LastActivityDate="2016-10-21T21:52:40.803" Title="What's it like to be a volunteer at the temporary airport set up at Burning Man?" Tags="&lt;career&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8364" PostTypeId="2" ParentId="8363" CreationDate="2014-08-27T14:24:19.437" Score="2" Body="&lt;p&gt;From the &lt;a href=&quot;http://88nv.burningman.com/advisory/#unicom&quot; rel=&quot;nofollow&quot;&gt;website&lt;/a&gt; that CGCampbell links to in his comment, it can also be found that the airport is located in Class G airspace. Class G is uncontrolled (see and avoid) airspace, so there is no air traffic control active in the airspace around the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also says flight following may be requested from Reno:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The controllers in Reno are familiar with our location, and it’s OK to give them Burning Man or Black Rock City as your destination when requesting Flight Following. However, if you’re lower than 10,000 feet they will most likely end radar services with you around Pyramid Lake. Close your flight plan prior to losing contact. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-08-27T16:05:54.870" LastActivityDate="2014-08-27T16:05:54.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8365" PostTypeId="1" AcceptedAnswerId="8366" CreationDate="2014-08-27T16:43:56.387" Score="20" ViewCount="38194" Body="&lt;p&gt;Is there a difference between &lt;strong&gt;Best&lt;/strong&gt; Rate of Climb and &lt;strong&gt;Maximum&lt;/strong&gt; Rate of Climb?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my research, best rate of climb trades ground distance for altitude (i.e. steeper climb, more altitude per unit time).  Since an aircraft cannot climb faster than its max rate, these appear to be two different labels for the same concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I missing some nuance between the two?&lt;/p&gt;&#xA;" OwnerUserId="3235" LastEditorUserId="19" LastEditDate="2017-01-16T13:45:28.093" LastActivityDate="2018-07-18T10:30:11.363" Title="What is the difference between Best Rate of Climb and Maximum Rate of Climb?" Tags="&lt;general-aviation&gt;&lt;flight-planning&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8366" PostTypeId="2" ParentId="8365" CreationDate="2014-08-27T17:53:22.840" Score="21" Body="&lt;p&gt;Generally when GA pilots talk about climb performance we speak of two different &lt;em&gt;airspeed&lt;/em&gt; values:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Best Rate of Climb &lt;em&gt;speed&lt;/em&gt;&lt;/strong&gt; (V&lt;sub&gt;y&lt;/sub&gt;) gets you the most altitude per unit time (feet per minute).&lt;br&gt;&#xA;When you want to get to cruise altitude quickly for maximum efficiency you'll aim for the best &lt;em&gt;rate&lt;/em&gt; of climb so you spend the least time at lower, less efficient altitudes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Best Angle of Climb &lt;em&gt;speed&lt;/em&gt;&lt;/strong&gt; (V&lt;sub&gt;x&lt;/sub&gt;) gets you the greatest altitude per unit of ground distance (feet per mile).&lt;br&gt;&#xA;When you've got a FAA-Standard 50-foot-tree at the departure end of the runway you'll aim for the best angle of climb to ensure you don't wind up in the tree.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those speeds are useful to us as pilots, but the exact rate of climb (feet-per-minute) for those speeds will vary: A fully loaded plane will climb more slowly than one that's just got the pilot and a few gallons of fuel on board, and that's where the &quot;maximum rate of climb&quot; enters into the discussion:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Maximum rate of climb&lt;/strong&gt; is the number of feet per minute you can get climbing at the &quot;best rate of climb&quot; airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone is being sloppy in their usage &quot;Maximum Rate of Climb&quot; could mean &quot;Best Rate of Climb&quot; (pitch for V&lt;sub&gt;y&lt;/sub&gt; and you get what you get), but if you're being precise in your usage and really talking about the &lt;em&gt;rate&lt;/em&gt; of climb it would mean &lt;a href=&quot;http://www.dept.aoe.vt.edu/~lutze/AOE3104/climb.pdf&quot;&gt;the theoretical maximum rate of climb&lt;/a&gt; in feet per minute based on the current conditions and aircraft weight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Maximum rate of climb under a given set of conditions is useful information to know if you need to clear terrain at some point on your flight path and want to be sure you can climb fast enough to do so: If you're starting from sea level and need to clear a 5000 foot mountain that's 5 minutes away but your plane can't manage more than 500 feet per minute at best-rate-of-climb speed under the current conditions you'll need to reconsider your flight plan to either avoid the mountain or climb in a circle somewhere until you can clear it.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-08-27T17:53:22.840" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8367" PostTypeId="2" ParentId="8365" CreationDate="2014-08-27T18:21:53.207" Score="21" Body="&lt;p&gt;Although &lt;a href=&quot;https://aviation.stackexchange.com/users/64/voretaq7&quot;&gt;voretaq7&lt;/a&gt; has already nicely &lt;a href=&quot;https://aviation.stackexchange.com/a/8366/65&quot;&gt;answered&lt;/a&gt; it, I wanted to present a &lt;a href=&quot;http://en.wikipedia.org/wiki/A_picture_is_worth_a_thousand_words&quot; rel=&quot;nofollow noreferrer&quot;&gt;picture worth thousand words&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QhB4z.png&quot; alt=&quot;Vx vs Vy&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;V&lt;sub&gt;X&lt;/sub&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Best angle of climb speed&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The greatest gain in altitude over a given horizontal distance. V&lt;sub&gt;X&lt;/sub&gt; is used to clear 50' obstacles and so forth.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;V&lt;sub&gt;Y&lt;/sub&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Best rate of climb speed&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The greatest gain in altitude over a given amount of time. V&lt;sub&gt;Y&lt;/sub&gt; is used on normal takeoffs and such.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-08-28T22:21:17.260" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8368" PostTypeId="2" ParentId="8365" CreationDate="2014-08-27T20:18:28.343" Score="14" Body="&lt;p&gt;Depends what is best in the particular case. Generally, best means highest climb speed, but there might be other things which should be optimized:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;highest flight path angle: This might be desired to avoid noise on the ground, or to escape unfriendly fire near the airport. For propeller aircraft, the optimum lift coefficient is&#xA;$$c_L = \frac{T\cdot\pi\cdot AR\cdot \epsilon}{4\cdot m\cdot g} + \sqrt{\left( \frac{T\cdot\pi\cdot AR\cdot \epsilon}{4\cdot m\cdot g}\right)^2 + \pi \cdot AR \cdot \epsilon \cdot c_{D0}}$$&lt;/li&gt;&#xA;&lt;li&gt;lowest fuel consumption per altitude gained: The highest climb speed is reached with full power, but maybe a lower power setting is more economical. In general, this is very close to the schedule with maximum climb speed. For propeller aircraft, the optimum lift coefficient for highest climb speed is the same as for minimum energy loss:&#xA;$$c_L = \sqrt{3 \cdot \pi \cdot AR \cdot \epsilon \cdot c_{D0}}$$&lt;/li&gt;&#xA;&lt;li&gt;highest energy gain (the sum of both altitude and speed gain is optimized): This is desired when you want to reach a point far up in a hurry, like a supersonic interceptor would.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The graph below shows lines of equal total energy (black, dashed) and of maximum altitude for given climb speeds over true airspeed (blue, solid). The red line connecting the tops of the blue lines gives the flight schedule for fastest altitude gain, and the green line cutting through the blue lines at their maximum of total energy gives the schedule for the total energy gain climb. The higher you fly, the wider is the difference in optimum speed between both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aXXXC.png&quot; alt=&quot;Isolines of climb speed&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient&lt;br&gt;&#xA;    $T \:\:\:\:$  thrust &lt;br&gt;&#xA;    $m \:\:\:\:$  aircraft mass &lt;br&gt;&#xA;    $g \:\:\:\:\:$  gravity &lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-08-27T20:33:33.970" LastActivityDate="2014-08-27T20:33:33.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8369" PostTypeId="2" ParentId="8303" CreationDate="2014-08-27T20:23:01.793" Score="3" Body="&lt;p&gt;There have been quite a few incidents. Here's one, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nycaviation.com/2013/08/pictures-nose-gear-of-united-boeing-767-300-collapsed-at-gate-at-iah/&quot; rel=&quot;nofollow&quot;&gt;http://www.nycaviation.com/2013/08/pictures-nose-gear-of-united-boeing-767-300-collapsed-at-gate-at-iah/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Google will find others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find links, but do know that there have been incidents caused by different issues such as ground locks not in place, failed struts, WoW logic failures and so on where when hydraulic power was applied, the gear retracted or collapsed.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2014-08-27T20:23:01.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8370" PostTypeId="1" CreationDate="2014-08-27T22:07:15.190" Score="34" ViewCount="37106" Body="&lt;p&gt;I thought I'd compare the accident rates of these two similar, competing, very successful aircraft.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                    737     A320&#xA;&#xA;Introduced          1968    1988&#xA;Number Built        8104    6171&#xA;Accidents/Incidents  329      60&#xA;Hull Loss Accidents  154      23&#xA;Fatalities          4287     782&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;These figures are from the respective Wikipedia pages. I assume they have not been the subject of edit-war falsification by fanboys of planemakers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wondered what might be the reason for the 737 seeming a much less safe plane.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The 737 design is 20 years older? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;But it's still in production, so 1988...current 737s can be built with many of the same safety features found in an A320 produced the same year. Were 3,500 of those fatalities in the first 20 years?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are lots more older less-safe 737s being flown by corner-cutting budget airlines in third-world kleptocracies?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are there that many 40-year old 737s in the hands of incompetent airlines?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 8,104 737s have, on average, flown many times more cycles than the 6,171 A320s? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;But they address the same market, why would their usage differ so markedly?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 737s have, together, flown many times more passenger-miles than the A320s? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;See above. Plus I imagine older 737s have mostly been retired.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My speculation doesn't seem very convincing to me. Is there a better explanation supported by reputable studies?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-28T13:59:43.983" LastActivityDate="2019-06-18T15:36:03.473" Title="Why does the Boeing 737 have 5 x the passenger fatalities of the Airbus 320?" Tags="&lt;safety&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8371" PostTypeId="2" ParentId="8361" CreationDate="2014-08-27T22:55:44.727" Score="7" Body="&lt;p&gt;In this experiment to observe a deliberate airliner crash&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment&quot; rel=&quot;noreferrer&quot;&gt;http://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;the crew exited in flight down the tail stairs...&lt;/p&gt;&#xA;" OwnerUserId="2701" LastActivityDate="2014-08-27T22:55:44.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8372" PostTypeId="2" ParentId="8370" CreationDate="2014-08-27T23:29:42.530" Score="29" Body="&lt;p&gt;Raw numbers like this are more-or-less useless. You would have to plot the accidents against the year to even begin to have something reasonable. You also need to remove non-airframe accidents like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;under-full-control crashes like controlled flight into terrain (pilot screwups have nothing to do with the airframe, and account for a lot of accidents)&lt;/li&gt;&#xA;&lt;li&gt;weather-related issues that are not pilot screwups (e.g. microbursts downing Delta 191)&lt;/li&gt;&#xA;&lt;li&gt;ground collisions that resulted in insurance writeoffs ( a &quot;hull loss&quot;)&lt;/li&gt;&#xA;&lt;li&gt;maintenance whoopsies like not tightening the fuel lines&lt;/li&gt;&#xA;&lt;li&gt;operational errors (Tenerife put a major dent in the 747's accident statistics, nothing to do with the plane)&lt;/li&gt;&#xA;&lt;li&gt;External forces ( WTC attacks, various shoot-downs like Malaysian and Korean Air etc. )&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Once you look at 3rd-owner and beyond you may find yourself in the less developed countries with poor maintenance, training etc. and then it gets a lot harder. It's even tricky with first-line carriers. Was Aloha Airlines Flight 243 (the Sunshine Roof flight) a design flaw, maintenance not fixing it properly, operations not grounding it for maintenace etc. etc.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-08-27T23:29:42.530" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="8374" PostTypeId="2" ParentId="8370" CreationDate="2014-08-28T04:11:37.927" Score="20" Body="&lt;p&gt;As I mentioned &lt;a href=&quot;https://aviation.stackexchange.com/questions/8370/why-does-the-boeing-737-have-5-x-the-passenger-fatalities-of-the-airbus-320#comment14830_8372&quot;&gt;in a comment earlier&lt;/a&gt;, there's no real way to answer this for certain: there are simply too many contributing factors to control for (many of which have nothing to do with the airframe).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broadly speaking I suspect the 20 years more service time, much of it back when aviation accidents were somewhat more common, is a large part of it.  &lt;a href=&quot;http://www.boeing.com/news/techissues/pdf/statsum.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boeing has a great presentation covering the commercial fleet accident rate from 1959-2012&lt;/a&gt;, and just looking at the accident rate graph shows how far commercial air travel has come in cutting their accident rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said while I do enjoy mercilessly mocking Airbus aircraft the A320 series has an enviable safety record, and certainly some part of that can be credited to the airframe and crew training programs in addition to the broader safety improvements in commercial aviation - just don't ask me to be specific as to &lt;em&gt;how much&lt;/em&gt;...&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-08-28T04:16:38.810" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8375" PostTypeId="2" ParentId="8370" CreationDate="2014-08-28T06:20:37.657" Score="45" Body="&lt;p&gt;For one, the early 737s had a design flaw which allowed the rudder to reach a hard-over position, and get stuck there. Boeing initially dragged their feet in rectifying this, so it took a number of accidents before this design flaw was corrected. This is a major contributor to the high number of fatalities in the early operational years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To have a more meaningful comparison, I would suggest to compare the fatalities per year, so the status in operational procedures can be excluded as a factor. As others have pointed out, this should give a more equal basis for a comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at &lt;a href=&quot;http://www.airfleets.net/crash/stat_plane.htm&quot; rel=&quot;noreferrer&quot;&gt;fatalities per year&lt;/a&gt;, beginning in 2000, these numbers emerge:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/gKvJB.png&quot; alt=&quot;fatalities table from 2000 to 2012&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need to factor in the number of flight hours per type per year, which I do not have available. But I would expect that the low fatality rate in the early 2000s is more due to the small number of A320s around. But if we just compare the 737 NG with the A320, this advantage is reversed, and still the A320 comes out slightly ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But thankfully, there are very few accidents for each type per year, so the statistical base is too low for a meaningful comparison. If we want to draw any conclusions, it could be that the A320 is indeed a safer aircraft, but the certainty of this conclusion is very low, being based on a very small number of accidents.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-06T13:34:18.093" LastActivityDate="2018-06-06T13:34:18.093" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="8376" PostTypeId="1" AcceptedAnswerId="8386" CreationDate="2014-08-28T07:01:42.597" Score="3" ViewCount="786" Body="&lt;p&gt;This picture of an Airbus A350 test aircraft shows multiple instruments on the flap fairings, wing fairing and on the empennage:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/ud4OErt.png&quot; alt=&quot;aerodynamic flow cones&quot;&gt;&#xA;Source: &lt;a href=&quot;https://www.flickr.com/photos/aircrafts/15029875556/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A380_TLS_A350 AIB199GG&lt;/a&gt; (&lt;a href=&quot;https://farm4.staticflickr.com/3889/15029875556_f41f8c7e97_o.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;high-res version&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are being described as 'aerodynamic flow cones'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are these -- what do they measure, and how?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="3151" LastEditDate="2014-08-28T11:49:41.407" LastActivityDate="2014-08-28T18:29:30.983" Title="What do aerodynamic flow cones measure?" Tags="&lt;aerodynamics&gt;&lt;measurement&gt;&lt;flight-testing&gt;&lt;airbus-a350&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8379" PostTypeId="1" AcceptedAnswerId="8382" CreationDate="2014-08-28T08:34:12.193" Score="20" ViewCount="3699" Body="&lt;p&gt;I have aircraft types like &lt;code&gt;Boeing 767-3Q8&lt;/code&gt;, &lt;code&gt;Boeing 767-33A&lt;/code&gt;, &lt;code&gt;Boeing 767-3P6ER&lt;/code&gt; and many others. I know what &lt;code&gt;ER&lt;/code&gt; means. But what is coded as &lt;code&gt;3Q&lt;/code&gt;, &lt;code&gt;33A&lt;/code&gt;, &lt;code&gt;3P6&lt;/code&gt; etc.?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I convert it back to more common types like &lt;code&gt;Boeing 767-300&lt;/code&gt;? Just replace last two symbols with &lt;code&gt;00&lt;/code&gt;?&lt;/p&gt;&#xA;" OwnerUserId="2421" LastEditorUserId="938" LastEditDate="2014-08-28T19:18:35.807" LastActivityDate="2018-02-01T13:53:27.433" Title="What does 3Q8 mean in the aircraft model Boeing 767-3Q8?" Tags="&lt;boeing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8380" PostTypeId="1" CreationDate="2014-08-28T08:55:19.160" Score="18" ViewCount="11759" Body="&lt;p&gt;Many pressurized aircraft have the type of plug doors that open by first swinging inside,  rotating about at least two axes, then moving through the opening and ending up outside parallel with the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm intrigued by the mechanism that makes this possible, but I have never been able to really see how these intricate hinges work. As a passenger it's hard to even witness the actual opening or closing of the door. Some drawings are to be found on the web, but none that I know of give a clear understanding of its workings. Does anybody know of a video or an animation that gives some insight?&lt;/p&gt;&#xA;" OwnerUserId="3353" LastEditorUserId="3353" LastEditDate="2014-08-28T09:08:27.173" LastActivityDate="2018-09-21T06:21:13.113" Title="How does the hinge mechanism of plug-type pressure doors work?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8381" PostTypeId="2" ParentId="8380" CreationDate="2014-08-28T09:25:45.967" Score="13" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=PLxwNv6Y3C0&quot; rel=&quot;noreferrer&quot;&gt;This video&lt;/a&gt; has a clear shot of how a classic plug door (in this case of a B737) works (or search for flight attendant training videos).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the door pops in (tipping a bit downwards) and then rotates on a axis in the center of the opening and then moves outside sideways. This is possible because of how the geometry works out, moving sideways negates the boor being wider than the opening and tipping down lets it fit height-wise.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="65" LastEditDate="2015-01-28T21:09:44.307" LastActivityDate="2015-01-28T21:09:44.307" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8382" PostTypeId="2" ParentId="8379" CreationDate="2014-08-28T09:59:12.937" Score="25" Body="&lt;p&gt;Those are Boeing's customer codes. They denote which airline the aircraft was originally built for, not necessarily the airline that owns/operates the aircraft currently. For example, Southwest's customer code is H4 but they operate some 737-7BD's, which are from the AirTran acquisition. In your case, the Q8 means it was originally built for ILFC, a leasing corporation.  A full list is available here: &#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Boeing_customer_codes&quot;&gt;http://en.wikipedia.org/wiki/List_of_Boeing_customer_codes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your assumption about replacing the customer code with 0s to get the plain old model is correct. &lt;/p&gt;&#xA;" OwnerUserId="3275" LastActivityDate="2014-08-28T09:59:12.937" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8383" PostTypeId="2" ParentId="8376" CreationDate="2014-08-28T10:15:00.487" Score="4" Body="&lt;p&gt;They are used to visualize the airflow over parts of the aircraft. See &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/88145main_H-1524.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; for more details about flow visualization techniques (flow cones are described at 2.2.1)&lt;/p&gt;&#xA;" OwnerUserId="2532" LastActivityDate="2014-08-28T10:15:00.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8384" PostTypeId="2" ParentId="8380" CreationDate="2014-08-28T14:55:45.263" Score="5" Body="&lt;p&gt;The door you mentioned is called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Plug_door&quot;&gt;Plug Door&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On some aircraft the plug door opens partially inward, and through a&#xA;  complex hinge design can be tilted to fit through the fuselage&#xA;  opening, or the door may have locking hinged panels at the top and&#xA;  bottom edges that can make it smaller than the opening, so that it may&#xA;  be swung outward.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=C9_BUR8rGtE&quot;&gt;This video&lt;/a&gt; shows opening and closing of such door from both outside and inside.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-08-28T14:55:45.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8385" PostTypeId="2" ParentId="8370" CreationDate="2014-08-28T15:33:12.840" Score="12" Body="&lt;p&gt;I'd suspect that the answer is a combination of a lot of factors, including all of the ones mentioned in the question.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•There are lots more older less-safe 737s being flown by corner-cutting budget airlines in third-world kleptocracies?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•Are there that many 40-year old 737s in the hands of incompetent airlines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In short, yes. They might not all be 40 years old, but, yes, there are tons of older 737s that were sold off to third-world airlines and/or airlines that simply operate in more dangerous areas. It's probably the single most common jet airliner in such situations.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•The 8,104 737s have, on average, flown many times more cycles than the 6,171 A320s?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•But they address the same market, why would their usage differ so markedly?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;While I'm not sure that their average use cases are very different for aircraft of the same age, there are far more old 737s than old A320s. A lot of the 737 fleet already had flown many cycles before the first A320 ever rolled out of the factory. The average 737 is significantly older than the average A320 and, thus, has flown more flight cycles. While the first A320 delivery was in 1988, the vast majority of A320 deliveries have been since 2000 (&lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;5,029 A320s out of 6,171 in service were delivered 2000 or later&lt;/a&gt;.) Based on their respective Wikipedia Orders and Deliveries numbers by year, the average fleet age of the 737 is &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;a little over 16 years&lt;/a&gt; while the average age of A320s is only &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;about 8.5 years&lt;/a&gt;. Of course, this also means that there are a lot more old 737s to be sold to the aforementioned third-world airlines than A320s.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•The 737s have, together, flown many times more passenger-miles than the A320s?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;•See above. Plus I imagine older 737s have mostly been retired.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In addition to the average 737 being significantly older (and, thus, having significantly more flight-cycles) than the average A320, you still have to consider that there are 31% more delivered 737s than A320s. In total, the B737 fleet has about &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;131,000 aircraft-years&lt;/a&gt; of history compared to about &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;52,800 aircraft-years&lt;/a&gt; for the A320. So, aircraft-years of service alone explains a factor of 2.5 (half the difference.)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;So, in short, I don't think any one factor explains the difference, but the sum of several factors, most of them being related to age, does explain the difference.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-08-28T15:33:12.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8386" PostTypeId="2" ParentId="8376" CreationDate="2014-08-28T18:22:20.870" Score="7" Body="&lt;p&gt;To expand a bit on the other explanations here, &quot;flow cones&quot; are one of the many methods used for flow visualization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When something is being tested in a wind tunnel or in flight, you usually can't see the air flow around the body. To be able to visualize the flow, something is added to the air, like smoke, or to the body, like flow cones or tufts. Tufts are basically just short lengths of string taped to the body at one end. Flow cones are small cones attached at their apex with string.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These items on the body have two main functions. Primarily, the flow cones or tufts will align them selves with the flow, allowing observers to see the direction of the air flow in that area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can also show flow separation. When the flow is attached to the body, it flows fairly smoothly along the surface. When the flow separates from the surface, it becomes much more turbulent and chaotic. The tufts or cones will show this as they are moved by the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow cones are larger than tufts, so they are much easier to see, which is important in cases like the picture you posted, where they will probably be observed from a chase plane at some distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more on flow separation, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375&quot;&gt;this question&lt;/a&gt;, or &lt;a href=&quot;https://www.youtube.com/watch?v=WFcW5-1NP60&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; of tufts on a stalling wing. For a comparison of tufts and cones, zoom in on &lt;a href=&quot;http://www.dfrc.nasa.gov/Gallery/Photo/X-29/Large/EC91-491-6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;this photo&lt;/a&gt; of the X-29A. The darker, larger objects behind the cockpit are cones, while the reddish, smaller ones further aft are tufts. You can also see smoke at the nose being used to visualize the flow.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-08-28T18:29:30.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8387" PostTypeId="2" ParentId="8272" CreationDate="2014-08-28T19:48:24.320" Score="1" Body="&lt;p&gt;As has already been mentioned, the primary method of avoiding other aircraft when flying VFR is to simply look out the window and don't fly into another aircraft. However, pilots in the same area are also usually in contact with each other by radio on a frequency that is determined by where the aircraft are operating. Pilots advise each other of their intentions by radio, which allows other pilots to know where they are and what they're planning to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific case of around airports was mentioned in a comment earlier. This is indeed the area where pilots have to be most vigilant in avoiding other traffic (because there's more of it around airports.) However, for uncontrolled airfields, there are specific, standard traffic patterns that pilots are supposed to fly when approaching or departing from a given runway. While pilots should always be vigilant in monitoring every direction, following this pattern allows pilots to know where to expect other aircraft to be around the airport and monitor those areas most closely. And, again, pilots approaching or departing from an airfield should advise other nearby pilots of their intentions via radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, at controlled airfields, pilots are required to maintain radio contact with the controllers and follow their instructions so long as it's safe to do so.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-08-28T19:48:24.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8389" PostTypeId="1" AcceptedAnswerId="8398" CreationDate="2014-08-29T01:51:21.247" Score="7" ViewCount="15031" Body="&lt;p&gt;Per Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Requirements for Instrument Rating in the United States are listed in section 61.65 of the Federal Aviation Regulation[2] are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;50 hours of Pilot in Command cross country &lt;/li&gt;&#xA;&lt;li&gt;40 hours of simulated or&#xA;actual instrument time &lt;/li&gt;&#xA;&lt;li&gt;15 hours of flight instruction towards&#xA;Instrument Rating&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Does this mean that 40 hours could be done on a simulator alone or does that overlap with the 15 hours with the instructor?&lt;/p&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="258" LastEditDate="2014-08-29T15:09:58.370" LastActivityDate="2014-08-29T15:17:47.973" Title="For a Part 61 IFR rating, how much can be done alone on a simulator?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;general-aviation&gt;&lt;instrument-flight-rules&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8390" PostTypeId="2" ParentId="8389" CreationDate="2014-08-29T03:55:15.210" Score="0" Body="&lt;p&gt;I don't know of &lt;strong&gt;any&lt;/strong&gt; simulators that students are allowed to log solo time in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the best of my knowledge, the 40 hours of actual or simulated instrument time is time that you could acquire while wearing a view limiting device (while your appropriately-rated friend sits in the right seat to scan for traffic), not time that you could get solo in a sim.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-08-29T03:55:15.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8391" PostTypeId="1" AcceptedAnswerId="12593" CreationDate="2014-08-29T10:28:18.757" Score="30" ViewCount="5820" Body="&lt;p&gt;With all this talk about drones flying around and delivering parcels for the merchant websites, I'm wondering from a &quot;landlubber's&quot; perspective, how much say I have over the airspace of my private land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I know this question is a bit broad and quite difficult because it might differ from country to country and also depend on the size of the land, for instance a farm vs. a house in the city. It might also be interesting to know how it affects a piece of private land with a private runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But since it is sadly the norm these days for every country to follow Europe's lead eventually on these kind of privacy issues, Europe's might be the most relevant in the end. Any general insight from you all on this would be very informative.&lt;/p&gt;&#xA;" OwnerUserId="659" LastEditorUserId="572" LastEditDate="2015-02-19T09:01:54.697" LastActivityDate="2021-04-11T19:01:03.397" Title="Do I have any authority over airspace above my land?" Tags="&lt;airspace&gt;&lt;easa-regulations&gt;" AnswerCount="7" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8392" PostTypeId="2" ParentId="8391" CreationDate="2014-08-29T11:02:24.413" Score="14" Body="&lt;p&gt;In the UK, you have rights up to about 1000 feet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.inbrief.co.uk/land-law/land-ownership.htm&quot; rel=&quot;noreferrer&quot;&gt;In Brief&lt;/a&gt; (a free legal-information website written by legal experts)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The common law distinguishes between two different types of airspace. The lower and Upper stratum.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The lower stratum is concerned with the portion immediately above the land and interference with this air space would effect the landowner’s reasonable enjoyment of the land and the structures upon it.&#xA;  Wrongful intrusions include; Overhanging branches of a neighbours trees and plants or  projecting eaves or advertising signs and Booms of cranes being used for construction work on neighbouring land.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Higher Stratum is something which exists above the height which is reasonably acceptable and necessary for the ordinary use and enjoyment of the land by it’s owner. The landowner has no greater rights to this airspace than any other member of the public.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;S. 76 Civil Aviation Act 1982  states that ‘the lower stratum is unlikely to extend beyond an altitude of much more than 500 or 1,000 feet above roof level, this being roughly the minimum permissible distance for normal overflying by any aircraft’ (Rules of the Air Regulations 2007, Sch 1, s. 3(5)). &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-08-31T20:01:27.353" LastActivityDate="2014-08-31T20:01:27.353" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8393" PostTypeId="2" ParentId="8391" CreationDate="2014-08-29T11:03:06.073" Score="14" Body="&lt;p&gt;This will differ from country to country, but I will give an example based on the German law, so you can derive how countries can work with airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, following &lt;a href=&quot;http://www.gesetze-im-internet.de/bgb/__905.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;BGB §905&lt;/a&gt;, the airspace above and ground below your property is also yours, unlimited.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Das Recht des Eigentümers eines Grundstücks erstreckt sich auf den Raum über der Oberfläche und auf den Erdkörper unter der Oberfläche.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But this is not the only relevant law, i.e. there are others that need to be looked at, such as those pertaining to airspace use in Germany, the &lt;a href=&quot;http://www.gesetze-im-internet.de/luftvg/__1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;LuftVG §1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) &lt;strong&gt;Die Benutzung des Luftraums durch Luftfahrzeuge ist frei&lt;/strong&gt;, soweit sie nicht durch dieses Gesetz, durch die zu seiner Durchführung erlassenen Rechtsvorschriften, durch im Inland anwendbares internationales Recht, durch Rechtsakte der Europäischen Union und die zu deren Durchführung erlassenen Rechtsvorschriften beschränkt wird.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The bold part basically says that all aircraft can use airspace freely, so technically, the drone/rc copter above your land is legal. If you want to claim you are an aircraft, irrespective of the size requirements, there is a lot of additional rules that need to be looked at, e.g. &lt;a href=&quot;http://www.gesetze-im-internet.de/luftvo/__6.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;LuftVO §6&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Die Sicherheitsmindesthöhe darf nur unterschritten werden, soweit es bei Start und Landung notwendig ist. Sicherheitsmindesthöhe ist die Höhe, bei der weder eine unnötige Lärmbelästigung im Sinne des § 1 Abs. 2 noch im Falle einer Notlandung eine unnötige Gefährdung von Personen und Sachen zu befürchten ist. &lt;strong&gt;Über Städten, anderen dicht besiedelten Gebieten, Industrieanlagen, Menschenansammlungen, Unglücksorten sowie Katastrophengebieten beträgt die Sicherheitsmindesthöhe mindestens 300 Meter (1.000 Fuß) über dem höchsten Hindernis in einem Umkreis von 600 Metern, in allen übrigen Fällen 150 Meter (500 Fuß) über Grund oder Wasser.&lt;/strong&gt; Segelflugzeuge, Hängegleiter und Gleitsegel können die Höhe von 150 Metern (500 Fuß) auch unterschreiten, wenn die Art ihres Betriebs dies notwendig macht und eine Gefahr für Personen und Sachen nicht zu befürchten ist.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The bold part states that over populated areas, a minimum safe altitude of &lt;code&gt;300m / 1.000ft&lt;/code&gt; must be maintained, unless you are taking off or landing with your drone. There is a plethora of other rules and regulations that need to be followed as well, another good SE question is this &lt;a href=&quot;https://aviation.stackexchange.com/questions/8312/what-is-the-maximum-altitude-allowed-to-fly-a-model-plane-copter-in-germany&quot;&gt;What is the maximum altitude allowed to fly a model plane/copter in Germany?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-08-31T09:21:15.917" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8394" PostTypeId="1" AcceptedAnswerId="8396" CreationDate="2014-08-29T11:12:58.613" Score="31" ViewCount="5790" Body="&lt;p&gt;Stealth aircraft have low visibility on radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that they strive to achieve low visibility &lt;strong&gt;optically&lt;/strong&gt; as well, e.g. spend some effort to not stand out too much &lt;em&gt;visually&lt;/em&gt; from the surroundings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;condensation trail&lt;/strong&gt; (during daytime against a bright sky) could definitely make an invisible aircraft visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what do stealth aircraft do against condensation trails?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they have technology aboard to avoid or minimize them?  Or it just a matter of choosing the right conditions (clouds, humidity, altitude, temperature) to fly?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="572" LastEditDate="2014-08-29T11:19:28.640" LastActivityDate="2014-08-30T00:37:33.277" Title="Do stealth airplanes need to limit contrail generation?" Tags="&lt;contrails&gt;&lt;stealth&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8395" PostTypeId="2" ParentId="8394" CreationDate="2014-08-29T12:53:53.953" Score="5" Body="&lt;p&gt;Stealth aircraft include options to reduce visual signatures, so yes.&lt;br/&gt;&#xA;This is achieved as a side effect of reducing the infra red signature, which is done by mixing the engine exhaust with environmental air before it is ejected, cooling the air a lot and thus making contrail generation far less likely.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-08-29T12:53:53.953" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8396" PostTypeId="2" ParentId="8394" CreationDate="2014-08-29T13:39:31.097" Score="33" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Do stealth airplanes need to limit contrail generation&lt;/strong&gt;?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not just stealth aircraft, most military aircraft are required to avoid contrails. Contrails form due to moisture in the aircraft's exhaust. &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110008150.pdf&quot;&gt;A tried and tested method by NASA&lt;/a&gt; is NOT to fly in regions of air that support contrail formation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ophir.com/contrail-detection/&quot;&gt;Ophir's Pilot Alert System&lt;/a&gt; which is used by the B-2 stealth bomber uses LIDAR (light detection and ranging) to differentiate contrails from clouds and tells the pilot to change his altitude as/when necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, &lt;strong&gt;it is essential to remember that though contrails are visible to the naked human eye they are NOT visible to Radars&lt;/strong&gt;. Ergo, until the stealth aircraft is really close (assuming it is on a SEAD/DEAD mission) one cannot see the contrails and by the time they do, it is too late. Moreover, stealth aircraft generally operate during night when contrails are less visible.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Stealth aircraft have low visibility on radar.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not necessarily. VHF radar should be able to detect them at long range. Moreover, RCS of aircraft is a complex phenomenon, depending on many stuff (frequency, aspect angle, polarization of signal etc). You will never find a &quot;static&quot; figure for this.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="97" LastEditDate="2014-08-29T15:27:50.013" LastActivityDate="2014-08-29T15:27:50.013" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8398" PostTypeId="2" ParentId="8389" CreationDate="2014-08-29T15:09:44.553" Score="6" Body="&lt;p&gt;The short answer: It depends.  Either 10, 20 or 30 hours of simulator/FTD/ATD time may be used, but all of it must be with an approved instructor.  None of it may be solo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of the requirements you posted are related to simulator time.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;50 hours of Pilot in Command cross country&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This can be done solo, as you are a rated pilot and thus PIC.  This need not be solo XC and can be done with a passenger or CFI.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;40 hours of simulated or actual instrument time&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this quote, simulated instrument time refers to time spent in the airplane during flight in visual meteorological conditions (VMC) that you are wearing a view-limiting device to simulate IMC.  While wearing a view-limiting device you &lt;strong&gt;must&lt;/strong&gt; be accompanied by another pilot who acts as your safety pilot.  Thus, none of this time may be accomplished solo.  You will always need another pilot either in simulated or actual instrument conditions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;15 hours of flight instruction towards Instrument Rating&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This time may overlap with the above (actually, must overlap), the regulation reads (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_165&quot;&gt;14 CFR 61.65&lt;/a&gt; (d)(2)):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) Forty hours of actual or simulated instrument time in the areas of operation listed in paragraph (c) of this section, of which 15 hours must have been received from an authorized instructor who holds an instrument-airplane rating...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now back to your question, what about simulator time?  For this we look further down to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_165&quot;&gt;14 CFR 61.65&lt;/a&gt; (h) and (i)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(h) Use of flight simulators or flight training devices. If the instrument time was provided by an authorized instructor in a flight simulator or flight training device—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A maximum of 30 hours may be performed in that flight simulator or flight training device if the instrument time was completed in accordance with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dc5271218191d2934701c2359b6db1c8&amp;amp;tpl=/ecfrbrowse/Title14/14cfr142_main_02.tpl&quot;&gt;part 142&lt;/a&gt; of this chapter; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) A maximum of 20 hours may be performed in that flight simulator or flight training device if the instrument time was not completed in accordance with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dc5271218191d2934701c2359b6db1c8&amp;amp;tpl=/ecfrbrowse/Title14/14cfr142_main_02.tpl&quot;&gt;part 142&lt;/a&gt; of this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(i) Use of an aviation training device. A maximum of 10 hours of instrument time received in an aviation training device may be credited for the instrument time requirements of this section if—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The device is approved and authorized by the FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) An authorized instructor provides the instrument time in the device;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) No more than 10 hours of instrument time in a flight simulator or flight training device was credited for the instrument time requirements of this section;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) A view-limiting device was worn by the applicant when logging instrument time in the device; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) The FAA approved the instrument training and instrument tasks performed in the device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The use of simulators and flight training devices is covered by (h) above, and the limit of 20 or 30 hours depends on how the training is conducted.  In either case, note that time must be &quot;provided by an authorized instructor&quot;.  Section (i) deals with lesser training devices that are limited to 10 hours but is also required to be conducted by an authorized instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reprising the short answer, any time spent in a simulator, flight training device or aviation training device where you are solo or without an authorized instructor does not count toward anything.  Sim time is &lt;em&gt;only&lt;/em&gt; valid when conducted by an authorized instructor.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-08-29T15:17:47.973" LastActivityDate="2014-08-29T15:17:47.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8399" PostTypeId="2" ParentId="8391" CreationDate="2014-08-29T16:51:08.260" Score="27" Body="&lt;p&gt;In the US you have, effectively, zero rights over the airspace above your land by default: Control of airspace is &lt;em&gt;entirely&lt;/em&gt; delegated to the FAA, and they're &lt;a href=&quot;http://bigstory.ap.org/article/faa-warns-public-against-shooting-guns-drones&quot; rel=&quot;noreferrer&quot;&gt;super serious about it&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you designate your land as an airport you can certainly &lt;a href=&quot;https://aviation.stackexchange.com/questions/3292/can-an-airport-without-an-faa-controlled-tower-have-their-own-tower-and-controll&quot;&gt;establish a control tower&lt;/a&gt; and request an airspace designation from the FAA - whether or not they approve your plan depends on the existing airspace around you though: If your airport would create a problem for an existing airport you'd probably not be able to get an airspace designation for it, and it may even be classified as an &lt;a href=&quot;https://aviation.stackexchange.com/questions/1282/what-does-objectionable-indicate-on-a-vfr-chart&quot;&gt;objectionable airport&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-08-29T16:51:08.260" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8400" PostTypeId="2" ParentId="8394" CreationDate="2014-08-30T00:37:33.277" Score="5" Body="&lt;p&gt;To directly answer your question, stealth aircraft have no special equipment to limit their contrails.  The military does though incorporate atmospheric data into their flight planning to minimize the creation of contrails especially during daytime operations.  This is true not just for stealth aircraft, but any aircraft which is concerned about being detected visually (such as reconnaissance aircraft, etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA has a &lt;a href=&quot;http://cloudsgate2.larc.nasa.gov/cgi-bin/site/showdoc?docid=33&amp;amp;cmd=latest&quot; rel=&quot;noreferrer&quot;&gt;website&lt;/a&gt; that projects the formation of contrails.  Essentially it looks at the relative humidity with respect to ice (RHI) in the atmosphere, and if it is greater than 70% the region is flagged.  Areas with greater than 100% RHI are very likely to support the formation of contrails.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-08-30T00:37:33.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8401" PostTypeId="2" ParentId="8272" CreationDate="2014-08-31T07:25:40.620" Score="1" Body="&lt;p&gt;Whilst there isn't really a good all round on board system for GA aircraft in the uk. It's good practice to get a Lower Airspace Radar Service from a nearby unit if available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The level of service depends on how busy the unit is, but generally you can get some form of deconfliction service which provides traffic information and avoidance steers.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-08-31T07:25:40.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8402" PostTypeId="2" ParentId="8391" CreationDate="2014-08-31T13:46:02.997" Score="4" Body="&lt;p&gt;Interesting question. In the US, it appears that the guiding principal is the FAA's definition of Navigable Airspace (another item borrowed from sailing?). And that &lt;a href=&quot;http://www.slate.com/articles/news_and_politics/explainer/2013/07/photographer_george_steinmetz_arrest_how_much_airspace_do_you_own.html&quot; rel=&quot;nofollow&quot;&gt;definition is changing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general this is anything above 500 feet, but of course there are exceptions. &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/AIR/air0603.html&quot; rel=&quot;nofollow&quot;&gt;This document&lt;/a&gt; provides some guidance.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="65" LastEditDate="2015-02-10T14:49:04.903" LastActivityDate="2015-02-10T14:49:04.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8403" PostTypeId="1" CreationDate="2014-08-31T13:51:04.957" Score="1" ViewCount="1881" Body="&lt;p&gt;I'm curious if this was a failure of the simulations or a result of the engine swap they did at the last moment. Originally, they said they could cruise at 200kts @ 10g/h fully loaded. Now its down to 155kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.panthera-aircraft.com/technical-data&quot; rel=&quot;nofollow&quot;&gt;http://www.panthera-aircraft.com/technical-data&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;Just wanted to add, for reference, a page which gave their original estimates.&#xA;&lt;a href=&quot;http://www.pipistrel-usa.com/models/panthera.html&quot; rel=&quot;nofollow&quot;&gt;http://www.pipistrel-usa.com/models/panthera.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also notice at the top of the page for the first link where they reference the 200kts with 4 people for 1000nm.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="3366" LastEditDate="2014-09-01T00:07:52.143" LastActivityDate="2016-05-12T03:15:14.563" Title="Why were the specifications of the Pipistrel Panthera downgraded?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8406" PostTypeId="2" ParentId="8403" CreationDate="2014-08-31T20:17:18.393" Score="7" Body="&lt;p&gt;This sounds like an overly optimistic marketing department which wanted to make the aircraft look better. Engineering would allow to predict top speed within a few percent, so I would blame neither the simulations nor the engine swap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The web page for the Panthera lists 155 kts only for the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;maximum range condition&lt;/a&gt;, which makes sense. Propeller aircraft need to fly rather slowly to maximize range. The cruise speed with maximum power is still close to 200 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please consider that the required engine power of propeller aircraft grows with the &lt;strong&gt;third&lt;/strong&gt; power of flight speed. To give you the 200 kts top speed, the plane would need to run the engine with 215% of the power setting (and fuel flow) needed for 155 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you know the installed power, you get reasonably good results just with the zero-lift drag and the propeller efficiency when you use this formula:&#xA;$$v = \left(\frac{2\cdot P\cdot \eta_{Prop}}{\rho\cdot F_{ref}\cdot c_{D0}}\right)^{1/3}$$&#xA;Nomenclature:&lt;BR&gt;&#xA;$v\:\:\:\:\:\:\:\:\:\:$ speed in [m/s]&lt;BR&gt;&#xA;$P\:\:\:\:\:\:\:\:\:\:$installed Power [W]&lt;BR&gt;&#xA;$\eta_{Prop}\:\:$ Propeller efficiency; use 0.85 if not known&lt;BR&gt;&#xA;$\rho\:\:\:\:\:\:\:\:\:$ density of air [kg/m³]&lt;BR&gt;&#xA;$F_{ref}\:\:\:\:$ Reference area for coefficients, usually wing area [m²]&lt;BR&gt;&#xA;$c_{D0}\:\:\:\:\:$ zero-lift drag coefficient&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The zero-lift drag coefficient for small propeller airplanes is around 0.02 to 0.025 if they have a retractable gear. A very well designed airplane might come down to 0.016, but that is already pushing it. To fly fast, a high wing loading is essential, and then the influence of all non-lifting components on the total drag is rather high. A well-designed airfoil might achieve a $c_{D0}$ of 0.0035, but the whole airplane will be closer to 0.02.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things get even worse when you aim for higher flight Mach numbers. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_328&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dornier 328&lt;/a&gt; turboprop was initially calculated for 320 kts cruise speed, but Marketing felt the need to claim 340 kts. The difference does not sound substantial, but all engineers thought they must be crazy over in Marketing. In the end, the Do-328  needed 30% more installed power to fulfill the promises made by the (rather irresponsible) Marketing department. The increased engine power indirectly caused an accident in flight test when a propeller (with an unchanged, but now too weak propeller mount) broke off in sideslip and cut through 1/3 of the fuselage. Luckily, the aircraft landed without further incident after that ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Disclaimer: This is from the back of my head, and I think I remember the facts and figures correctly. If any of you know more, please edit the last paragraph!)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-09-08T07:15:24.293" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8408" PostTypeId="1" AcceptedAnswerId="8413" CreationDate="2014-08-31T22:00:00.463" Score="16" ViewCount="18355" Body="&lt;p&gt;I've realized that some pilots turn the air conditioning units (also called 'packs') OFF during takeoff, like in this video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://youtu.be/nhXXjNybx6A?t=7m35s&quot;&gt;LH456 Takeoff Video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any operational reason for that?&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="3386" LastEditDate="2017-06-11T22:28:30.113" LastActivityDate="2017-08-07T13:11:14.217" Title="Why do pilots disable the air-conditioning 'packs' during takeoff?" Tags="&lt;takeoff&gt;&lt;pack&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8409" PostTypeId="1" AcceptedAnswerId="8511" CreationDate="2014-08-31T22:15:17.647" Score="7" ViewCount="5682" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;n=pt14.1.21&amp;amp;r=PART&amp;amp;ty=HTML#se14.1.21_19&quot;&gt;FAR 21.9&lt;/a&gt; provides the ability to install parts that were &quot;Produced by an owner or operator for maintaining or altering that owner or operator's product&quot;. This seems like a pretty broad scope of authority for aircraft owners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under what circumstances are owner-produced parts typically used, and what requirements are imposed on the part (and the owner producing it)?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-09-08T19:43:50.307" Title="How are &quot;Owner-Produced Parts&quot; handled under FAA regulations?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8410" PostTypeId="2" ParentId="8408" CreationDate="2014-09-01T01:19:11.957" Score="7" Body="&lt;p&gt;Best answer that I can think of, without the exact engineering or design info, is that since the A/C packs are run with engine bleed air, if you need the extra thrust from the engines, you'd turn off the packs for that extra power for take off...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I did my dispatcher certificate, we used the 727... and from my notes, you'd get a 1500 lbs increase in runway limit performance, with the Packs off.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-09-01T01:19:11.957" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8412" PostTypeId="1" CreationDate="2014-09-01T03:07:45.950" Score="8" ViewCount="6523" Body="&lt;p&gt;I assume it has a lot to do with the stall characteristics, but with the SR20/22 having a combined 1.6/100,000 Fatal rate and the DA40 having .35/100,000 Fatal, it seems like a very stark difference. Additionally, the SR-- has a ballistic parachute and the DA40 does not.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2018-10-27T03:56:16.140" Title="Why is the fatality rate in the Diamond DA40 so remarkably lower than the SR20/22?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8413" PostTypeId="2" ParentId="8408" CreationDate="2014-09-01T05:34:39.217" Score="18" Body="&lt;p&gt;The &quot;packs&quot; (or A/C on the aircraft) are powered by engine bleed air. When bleed air is extracted from the engines, less thrust can be produced. This may be a problem if the airplane is taking off at a high elevation airport or the departure path requires a certain climb gradient to clear obstacles. This action does create some discomfort in the cabin so it's usually not preferred unless required for safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some newer airplanes are manufactured with an &quot;APU to pack&quot; configuration - i.e. the pilots leave the APU running during takeoff, which provides bleed air to power the packs. The workload on the engines are now reduced.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2017-06-11T22:29:45.437" LastActivityDate="2017-06-11T22:29:45.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8414" PostTypeId="2" ParentId="8412" CreationDate="2014-09-01T07:25:35.227" Score="5" Body="&lt;p&gt;Not sure how true it is, but one theory I've heard about the high accident rate of the SR22 is the parachute. Every added safety feature tends to make people more careless. Was the same when airbags were first introduced in cars, accident rates shot up for a while before slowly trending down again.&lt;br/&gt;&#xA;Also, the DA40 is used more often as a trainer, while the SR22 is more often used by relatively inexperienced pilots who do have a license. Might well make a difference (student pilots tend to be more aware of the limits of their skill and knowledge than cocky fresh graduates who think that now that they are certified to know it all they really do know it all). And often that student will have an experienced instructor in the cockpit with him as well.&lt;br/&gt;&#xA;&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="718" LastEditDate="2014-09-01T13:55:34.173" LastActivityDate="2014-09-01T13:55:34.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8415" PostTypeId="2" ParentId="8412" CreationDate="2014-09-01T07:42:39.163" Score="5" Body="&lt;p&gt;Compared to other 180 hp airplanes the DA40 handles strong cross-winds better. It also has good visibility because the canopy bow is so far aft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://philip.greenspun.com/flying/diamond-da40&quot; rel=&quot;noreferrer&quot;&gt;http://philip.greenspun.com/flying/diamond-da40&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In defense of the SR20 what can be said is that the SR20 has a split-airfoil wing design that guarantees the wings will stall near the fuselage first, leaving the outer wings and ailerons unstalled. The result is very controllable performance right up to and including the stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://philip.greenspun.com/flying/plastic-airplanes&quot; rel=&quot;noreferrer&quot;&gt;http://philip.greenspun.com/flying/plastic-airplanes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, &lt;strong&gt;a majority of accidents involving the DA40,SR20/22 or any  4-seat GA airplanes is almost always caused by Pilot error&lt;/strong&gt;. So , it is not about the DA40 being more safe than the SR20. Splitting high and low fleet hours may result in too high a number. Ergo, the math is not precise. &lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-09-01T07:42:39.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8416" PostTypeId="1" CreationDate="2014-09-01T08:22:09.367" Score="3" ViewCount="281" Body="&lt;p&gt;I would like to know where and what to search in order to have information on a specific flight (i.e. scheduled departure time, real departure time, technical failures reported, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that this information can be found :&#xA;in the airplane's log&#xA;at the control tower (or the aeronautical uthorities)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you please tell me more about all this, especially the technical name of the different documents and the information contained within?&lt;/p&gt;&#xA;" OwnerDisplayName="user3390" LastEditorUserId="97" LastEditDate="2014-11-02T15:29:07.400" LastActivityDate="2014-11-02T15:29:07.400" Title="What information on a specific flight can be retrieved?" Tags="&lt;logging&gt;&lt;website&gt;&lt;datasets&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8417" PostTypeId="1" AcceptedAnswerId="35910" CreationDate="2014-09-01T12:08:16.710" Score="14" ViewCount="1825" Body="&lt;p&gt;On Wikipedia, a few obscure ex-Soviet airports like &lt;a href=&quot;https://en.wikipedia.org/wiki/Tamchy_Airport&quot;&gt;Tamchy Airport&lt;/a&gt; in Issyk-Kul, Kyrgyzstan list &quot;Russian IATA codes&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;IATA: none (ИКУ), ICAO: UCFL&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&quot;ИКУ&quot; being Cyrillic for &quot;IKU&quot;, which is not a recognized code according to the &lt;a href=&quot;http://www.iata.org/publications/Pages/code-search.aspx&quot;&gt;official IATA finder&lt;/a&gt;.  &lt;a href=&quot;http://g-avia.ru/kody_gorodov_vseh_stran_&quot;&gt;This Russian site&lt;/a&gt; lists &quot;city codes&quot; (Коды городов), but gives no source, and as bonus gives the ICAO code for Иссык-Куль as &quot;UAFR&quot; (which gcmap.com has never heard of).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where do these codes come from?  And does IATA play any part in maintaining them?&lt;/p&gt;&#xA;" OwnerUserId="3393" LastEditorUserId="9151" LastEditDate="2017-02-28T10:04:26.977" LastActivityDate="2017-02-28T11:31:39.093" Title="What is a &quot;Russian IATA code&quot;?" Tags="&lt;airport&gt;&lt;iata&gt;&lt;russia&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8418" PostTypeId="2" ParentId="8416" CreationDate="2014-09-01T13:20:11.100" Score="2" Body="&lt;p&gt;For historical data, I really like &lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;http://flightaware.com/&lt;/a&gt;. Even a GA pilot, if one requests VFR flight following, can see a history of his radar returns which can be useful as a student pilot. It also allows you to gather information on commercial flight number.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2014-09-01T13:20:11.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8419" PostTypeId="1" AcceptedAnswerId="8421" CreationDate="2014-09-01T13:51:50.310" Score="4" ViewCount="916" Body="&lt;p&gt;Having just been to a bunch of air museums, I've seen quite a few of these:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PjVH9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt; img credit &lt;a href=&quot;http://www.thewire.com/global/2013/02/iran-new-stealth-fighter-jet-fake/61781/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.thewire.com/global/2013/02/iran-new-stealth-fighter-jet-fake/61781/&lt;/a&gt; &lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those red pads they put in the jet engines that say &quot;remove before flight&quot; - what happens if I try to start the engine with that pad in there? Would the exhaust just blow it out?&lt;/p&gt;&#xA;" OwnerUserId="14" LastActivityDate="2014-09-01T14:36:01.707" Title="What happens if I don't remove the &quot;remove before flight&quot; pad before flight?" Tags="&lt;preflight&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8420" PostTypeId="2" ParentId="8408" CreationDate="2014-09-01T14:18:43.613" Score="13" Body="&lt;p&gt;Pilots will turn off the packs for takeoff if maximum engine performance is needed or if there is a need to prioritize a high demand bleed draw.  The particulars of the situations calling for a packs-off takeoff is airframe specific.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the EMB-145, normal takeoff was with the APU bleed powering the packs.  The specific configuration calls for engine bleeds off, APU bleed on, cross-bleed valve open and packs on.  This lets the APU be the sole source of bleed air and the packs the sole consumer of bleed air.  This is a typical configuration, but assumes that the APU is operational and that anti-ice will not be needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the APU is inoperative or anti-ice is called for, then the takeoff configuration becomes engine bleeds on, APU bleed off, cross-bleed off, packs off.  This isolates the APU from the bleed system (but keeps it available as a 5th generator) and makes the engines the bleed sources with no draw from the packs.  This configuration with the APU inop allows the engines to avoid a performance hit from the bleed air taps (drawing compressed air at the 9th and 14 compressor stages of this particular engine).  For anti-ice takeoffs, this configuration provides the ability to provide anti-ice as the APU bleed source is not powerful enough for this on the EMB-145. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The particular pneumatic configuration details will vary by airframe, and as mentioned in comments to the other answers, some airplanes have limitations on bleed valves being closed (e.g. to keep a pneumatic powered hydraulic pump operational) and some do not.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, the reason for a packs off takeoff is likely for takeoff performance or for high demand needs such as anti-ice.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-09-01T14:18:43.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8421" PostTypeId="2" ParentId="8419" CreationDate="2014-09-01T14:36:01.707" Score="9" Body="&lt;p&gt;As Ratchet Freak says, it's going to blow away or cause the engine to fail. Latter might happen if it sits tight enough that it doesn't get blown away before overpressure develops in the engine.&lt;br/&gt;&#xA;Not a good thing, damage may happen.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;My guess most likely outcome is that it will be blown back, possibly colliding with parts of the aircraft (and thus causing damage) or hitting the hangar wall or whatever else is behind the aircraft with some speed (unless there's a lot of clear area, in which case it'd flutter to the ground), if it's not overfastened.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And to be complete, it's a cover to prevent things from getting into the engine while the aircraft is parked. Dust, animals, anything.&lt;br/&gt;&#xA;There will be others on the air intakes as well.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-09-01T14:36:01.707" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8422" PostTypeId="1" AcceptedAnswerId="8426" CreationDate="2014-09-01T15:17:06.183" Score="6" ViewCount="525" Body="&lt;p&gt;AWS says the SIGWX charts are issued at 0000, 0600, 1200, and 1800 UTC, which I assume matches the &lt;code&gt;VT&lt;/code&gt; times on the charts themselves. What confuses me is AWS' parenthesized statement &lt;code&gt;based on the current ETA model available&lt;/code&gt; (&lt;a href=&quot;http://aviationweather.gov/products/swl/info&quot; rel=&quot;nofollow&quot;&gt;http://aviationweather.gov/products/swl/info&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say it's 1100Z on Monday morning, and I'm trying to use the SIGWX charts to predict weather as far in the future as possible using SIGWX charts available to me at this time (again 1100Z on Monday morning), and only SIGWX charts. I know there are other information sources, but this question pertains only to SIGWX charts and their timing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Which SIGWX charts are relevant for future weather developments (at 1100Z Monday)? The only two updates scheduled at 1200 and 1800 at this time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) I'm &lt;em&gt;assuming&lt;/em&gt; that today's (Monday's) 0000Z and 0600Z SIGWX charts will be updated &lt;code&gt;using the current ETA model available&lt;/code&gt; at the time the 1200Z chart is published. So is it fair to say that &quot;all&quot; SIGWX charts are updated when a SIGWX chart is published (at 0000, 0600, 1200 and 1800)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for any clarification.&lt;/p&gt;&#xA;" OwnerUserId="3396" LastEditorUserId="1696" LastEditDate="2015-12-15T16:51:57.623" LastActivityDate="2015-12-15T16:51:57.623" Title="How do SIGWX chart updates work?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8423" PostTypeId="1" CreationDate="2014-09-01T17:05:49.613" Score="2" ViewCount="663" Body="&lt;p&gt;I'm trying to program a BMP180 pressure/temperature sensor to calculate altitude.  The method I've seen used is to input your current base station altitude to calculate the sea-level pressure.  It seems a little tedious to input the base station altitude everytime, so I was wondering if it is possible to calculate sea-level pressure without a known base station pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been trying to calculate sea-level pressure through iteration.  I would set the default sea-level pressure at 1013.25 mb, use this number to calculate an estimated altitude, use the estimated altitude as my current base-station altitude to calculate a new sea-level pressure, use this new number to calculate an estimated altitude, etc...  However, I noticed that my results are diverging.  Is there a better way to calculate the sea-level pressure?&lt;/p&gt;&#xA;" OwnerUserId="3398" LastEditorUserId="97" LastEditDate="2015-05-03T00:59:35.230" LastActivityDate="2015-05-03T00:59:35.230" Title="Is it possible to calculating sea-level pressure with an unknown base station altitude?" Tags="&lt;altimeter&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8424" PostTypeId="2" ParentId="8423" CreationDate="2014-09-02T02:39:36.013" Score="3" Body="&lt;p&gt;Since answers aren't really supposed to go in the comment area:&lt;/p&gt;&#xA;&lt;h3&gt;If all you have is ambient temperature and ambient pressure, and no elevation information, there is no way you can calculate sea-level pressure.&lt;/h3&gt;&#xA;&lt;p&gt;Credit for the content of this answer goes to &lt;a href=&quot;https://aviation.stackexchange.com/questions/8423/calculating-sea-level-pressure-with-unknown-base-station-altitude#comment14981_8423&quot;&gt;Henning Makholm&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-02T02:39:36.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8425" PostTypeId="2" ParentId="8423" CreationDate="2014-09-02T03:13:26.757" Score="4" Body="&lt;p&gt;Calculating sea level pressure depends on knowing your altitude.  A function that does this is the hypsometric equation $$\Delta z = \dfrac{R \overline{T}}{g}\ln\dfrac{p_1}{p_2}.$$  This function gives the depth ($\Delta z$) of an atomspheric layer with average temperature $\overline{T}$ between pressure levels $p_1$ and $p_2$.  In your case, the station pressure is known and the height of mean sea level is known; in order to calculate your height or to calculate sea level pressure, you must know the other quantity.  The average temperature is also an unknown, but you can approximate this or use a value based on the lapse rate of the standard atmosphere. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-09-03T00:29:11.457" LastActivityDate="2014-09-03T00:29:11.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8426" PostTypeId="2" ParentId="8422" CreationDate="2014-09-02T03:24:19.220" Score="12" Body="&lt;h2&gt;First, an explanation of &amp;quot;the ETA model&amp;quot;&lt;/h2&gt;&#xA;&lt;p&gt;The science of weather prediction is the science of data analysis.  Meteorologists receive data from weather reporting stations worldwide, and from that data, they attempt to predict the future, using the laws of physics as well as assumptions and educated guesses.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Educated guesses?!  Say what?!&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;That's right.  Weather is one of the original &lt;a href=&quot;http://en.wikipedia.org/wiki/Chaos_theory&quot; rel=&quot;noreferrer&quot;&gt;chaotic systems&lt;/a&gt;, and although the weather obeys physical laws, we can't gather enough information about the current state of the atmosphere to predict what will happen in the long term with any degree of accuracy.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Bummer.  So what are all the computers for?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Well, we've found that supercomputers &lt;strong&gt;can&lt;/strong&gt; predict the weather out to a few days ahead with a reasonable degree of accuracy, even without perfect information.  They do this by applying educated guesses and rules of thumb.  Using different assumptions gives a different forecast model.  Some of the more well-known models are the &lt;a href=&quot;http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&amp;amp;model=GFS&amp;amp;area=NAMER&amp;amp;ps=model&quot; rel=&quot;noreferrer&quot;&gt;GFS&lt;/a&gt;, the &lt;a href=&quot;http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&amp;amp;model=NAM&amp;amp;area=NAMER&amp;amp;ps=model&quot; rel=&quot;noreferrer&quot;&gt;NAM&lt;/a&gt;, and the &lt;a href=&quot;http://www.weather.unisys.com/ecmwf/index.php&quot; rel=&quot;noreferrer&quot;&gt;EMCWF&lt;/a&gt;.  The ETA is one of the lesser-used models.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Great.  So what does &amp;quot;based on the current ETA model&amp;quot; mean?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Simple.  It means that the SIGWX chart gets created based on the most recent data that the ETA supercomputer churned out.  If the chart is supposed to come out at 1800 UTC, but the ETA model run doesn't complete until 1845, then that new forecast data doesn't make it into that chart.&lt;/p&gt;&#xA;&lt;h2&gt;Enough.  Just answer my questions.&lt;/h2&gt;&#xA;&lt;p&gt;Okay.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;which SIGWX charts are relevant for future weather developments (at&#xA;1100Z Monday)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;All the SIGWX charts are relevant&lt;/strong&gt;, but the newer charts will have the newer forecast data.  That doesn't &lt;em&gt;necessarily&lt;/em&gt; mean that they're going to be more accurate, but they &lt;em&gt;probably&lt;/em&gt; will be.&lt;/p&gt;&#xA;&lt;p&gt;To use your example, it's 1100Z on Monday morning.  The 0000 chart says &amp;quot;IFR&amp;quot; but the 0600 chart says &amp;quot;No IFR&amp;quot;.  There might still be IFR out your window - nothing says that the supercomputer will get it right.  Maybe the older one was more correct than the newer one.  Doesn't happen often, but is it possible?  Sure.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;So is it fair to say that &amp;quot;all&amp;quot; SIGWX charts are updated when a SIGWX&#xA;chart is published (at 0000, 0600, 1200 and 1800)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;No, as soon as a chart comes out, it becomes part of history.&lt;/strong&gt;  Charts are not updated with new weather information; they remain as a historical record of what was &lt;em&gt;predicted&lt;/em&gt; to occur, given the best information possible at the time (which, for the forecasters, can be just as valuable if not more valuable, to see where they went wrong in the past).&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-02T03:24:19.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8427" PostTypeId="2" ParentId="114" CreationDate="2014-09-02T13:02:29.153" Score="2" Body="&lt;p&gt;According to the FAA Modernization and Reform Act of 2012 as (1) the aircraft is flown strictly for hobby or recreational use; (2) the aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization; (3) the aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization; (4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft; (5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower…with prior notice of the operation; and (6) the aircraft is flown within visual line sight of the operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/uas/publications/model_aircraft_operators/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/uas/publications/model_aircraft_operators/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA has released a set of &quot;Dos&quot; &amp;amp; &quot;Don'ts&quot; related to flying UAVs(drones):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/uas/publications/model_aircraft_operators/assets/media/model-aircraft-infographic.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/uas/publications/model_aircraft_operators/assets/media/model-aircraft-infographic.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Regulations and Policies pertaining to the use of UAVs(Drones) in US airspace is available on the FAA website&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/uas/regulations_policies/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/uas/regulations_policies/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-09-02T13:02:29.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8428" PostTypeId="1" AcceptedAnswerId="8445" CreationDate="2014-09-02T13:50:02.553" Score="13" ViewCount="2050" Body="&lt;p&gt;With fly-by-wire and computers between pilot's command and flight control surfaces, it is easy to imagine the implementation of an autopilot inside the computer, but I read somewhere that autopilots existed before WW2. They were made only to maintain altitude and heading, but worked at a that time with the mechanical linked between pilot and control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How did these old autopilots work?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="2556" LastEditDate="2016-02-22T13:19:18.900" LastActivityDate="2016-02-23T02:19:22.197" Title="How did old autopilots work?" Tags="&lt;autopilot&gt;&lt;aviation-history&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8429" PostTypeId="1" AcceptedAnswerId="8437" CreationDate="2014-09-02T14:03:23.427" Score="15" ViewCount="11923" Body="&lt;p&gt;I would like to know whether the APU of modern commercial airliners consumes more or less fuel than a jet engine. Of course, this will vary between aircraft types, so what comparisons in fuel usage are there on a modern jet such as a B737 or A320? What is the ratio between an engine hourly fuel consumption and the APU hourly consumption?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1711" LastEditDate="2014-09-03T07:33:50.947" LastActivityDate="2021-03-11T18:37:24.253" Title="Does the APU consume a lot of fuel compared to a jet engine?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8430" PostTypeId="2" ParentId="8428" CreationDate="2014-09-02T14:10:22.197" Score="14" Body="&lt;p&gt;It used a set of &lt;a href=&quot;http://en.wikipedia.org/wiki/Gyroscopic_autopilot&quot;&gt;gyroscopes&lt;/a&gt; and pendulums that would correct the plane's attitude when it deviates. They were usually enhanced with pneumatic or hydraulic power to actually move the control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the &lt;a href=&quot;http://en.wikipedia.org/wiki/V-1_flying_bomb#Guidance_system&quot;&gt;V-1 flying bomb&lt;/a&gt; (WW2 German UAV) could fly across the Channel and initiate a dive after a preset distance. It remained on course using a pendulum for pitch control and a gyroscope for yaw control. It used its inherent stability for roll control (no ailerons).&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-09-02T14:10:22.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8431" PostTypeId="2" ParentId="8429" CreationDate="2014-09-02T14:14:44.310" Score="11" Body="&lt;p&gt;The APU consumes less fuel because it doesn't have to contribute thrust to the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many APUs have the same generator capacity as a propulsion engine.  But they don't produce thrust. They can run at an optimum RPM for the generator requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A320&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                   APU&#xA;Ground operations: 130 kg/hour           90 kVA&#xA;FL200:             65 &#xA;FL300:             51&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;On a short flight each main engine might consume an average of 1260 kg/hour.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-02T14:21:17.607" LastActivityDate="2014-09-02T14:21:17.607" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8432" PostTypeId="1" AcceptedAnswerId="8436" CreationDate="2014-09-02T14:51:15.537" Score="27" ViewCount="17331" Body="&lt;p&gt;I saw that some aircraft's rudder is composed of an upper rudder and a lower rudder (B727, A380, ...) as illustrated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kGttS.png&quot; alt=&quot;Flight control&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/9/9e/Boeing_727_flight_control_surfaces.svg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder how does it work compare to a normal rudder and what are the pros and cons of the two-parts rudder over the one-part rudder?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="65" LastEditDate="2015-03-31T14:57:44.767" LastActivityDate="2020-06-01T09:52:29.853" Title="What is the advantage of the two-part rudder and how does it work?" Tags="&lt;flight-controls&gt;&lt;rudder&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8433" PostTypeId="2" ParentId="8432" CreationDate="2014-09-02T14:56:23.387" Score="5" Body="&lt;p&gt;It allows one part to jam while the pilot retains control over the other part. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the higher portion of the rudder induces roll when deflected, at high speeds (where control surface deflection is more effective) only the lower portion can be deflected to minimize this effect.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-09-02T14:56:23.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8434" PostTypeId="1" CreationDate="2014-09-02T15:11:25.007" Score="7" ViewCount="1597" Body="&lt;p&gt;I'm looking for historical, daily locations of the North Atlantic Track (NAT, published daily as NOTAM) system for the past 10/20 years.  I've already contacted what feels like dozens of organizations (FAA, Gander, Shanwick, ...) but no-one seems to actually archive the NAT locations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd be extremely grateful for any pointers towards possibilities to acquire these data, be it free or paying.&lt;/p&gt;&#xA;" OwnerUserId="3401" LastEditorUserId="97" LastEditDate="2015-05-03T00:56:59.447" LastActivityDate="2015-05-03T00:57:47.803" Title="Where to find historical locations of North Atlantic Tracks?" Tags="&lt;datasets&gt;&lt;notam&gt;&lt;transatlantic&gt;&lt;nat&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8435" PostTypeId="2" ParentId="5246" CreationDate="2014-09-02T15:44:29.987" Score="-1" Body="&lt;p&gt;This kind of laser is class 3B laser. You may not be allowed to possess it.&#xA;Even if you are, this laser come with serious technical restriction such as deactivation if you point it upward.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2014-09-02T15:44:29.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8436" PostTypeId="2" ParentId="8432" CreationDate="2014-09-02T16:02:48.547" Score="39" Body="&lt;p&gt;This is called Split Rudder and it provides redundancy. They run on different systems so if one fails, the other one can be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture of a split rudder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0Qujo.jpg&quot; alt=&quot;Split Rudder&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Split rudders also provide a finer high speed control, in that only the lower one moves at high speed, reducing the exposed surface area and therefore the control effect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very importantly, there is a structural benefit. When we use the rudder it imposes a twisting load on the vertical fin. By only using the lower rudder, when the aircraft is at high speed, we reduce the twisting moment and transfer that load to a bigger, stronger, part of the airframe. The principle is the same as why the outboard ailerons are disabled at high speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The patent information is &lt;a href=&quot;http://www.google.com/patents/US5655737&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-10-20T21:17:10.717" LastActivityDate="2014-10-20T21:17:10.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8437" PostTypeId="2" ParentId="8429" CreationDate="2014-09-02T16:13:22.127" Score="24" Body="&lt;p&gt;To give a comparison with an engine at idle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the 737 NG, the &lt;a href=&quot;http://www.b737.org.uk/apu.htm#Pack_Operation&quot;&gt;APU&lt;/a&gt; can use &lt;strong&gt;240 lb/hr&lt;/strong&gt; when under load. It is rated at 90 kVA, &lt;a href=&quot;http://www.b737.org.uk/generators.htm&quot;&gt;same as the generator&lt;/a&gt; on each engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines can use about &lt;strong&gt;850 lb/hr&lt;/strong&gt; &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/3CM032%20-%20CFM56-7B24%20%2809.04.2013%29.pdf&quot;&gt;at idle&lt;/a&gt;, which from those figures is about 1/10 of fuel flow at full (takeoff) power. So the engines use about 4 times as much fuel (each) as the APU does to just provide power. Of course these values will vary based on ambient conditions and the load placed on the systems (like the bleed air system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why if a plane has to stop away from the gate for a while, they will shut down the engines and run on the APU.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-02T19:43:46.330" LastActivityDate="2014-09-02T19:43:46.330" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8438" PostTypeId="1" AcceptedAnswerId="8442" CreationDate="2014-09-02T16:47:15.763" Score="10" ViewCount="2606" Body="&lt;p&gt;I was inspired by stealth planes like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Phantom_Ray&quot; rel=&quot;noreferrer&quot;&gt;Boeing Phantom Ray&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Shi4.jpg&quot; alt=&quot;Phantom Ray&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to make a model aircraft that's as thin as possible, and has integral engines that are not visible from the outside. I have been wondering how this might be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way might be to place a radial blower in the centre of the fuselage. Radial blowers suck in air through their rotary axis, and blow it out the sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/A0k2S.jpg&quot; alt=&quot;Radial blower&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, they are housed so that air is constrained to come out in one direction. However, you can always give the air two exit ports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if something like this might make a good engine for a plane? The air intake would be at the top of the plane, and the exhausts would be at the back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hYS9C.png&quot; alt=&quot;Stealth plane with blower engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Would a single large engine have a power:weight benefit over two smaller engines?&lt;/li&gt;&#xA;&lt;li&gt;Would the intake actually provide additional lift by reducing the pressure above the plane?&lt;/li&gt;&#xA;&lt;li&gt;Might be intake be starved of air if the plane is acting as a lifting body?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3391" LastEditorUserId="97" LastEditDate="2015-05-03T00:55:55.700" LastActivityDate="2016-01-02T20:49:14.320" Title="Could you use radial blowers to propel a model aircraft?" Tags="&lt;single-engine&gt;&lt;model-aircraft&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8439" PostTypeId="2" ParentId="8438" CreationDate="2014-09-02T17:49:11.077" Score="4" Body="&lt;p&gt;Some smaller turbine engines actually do use &lt;a href=&quot;http://en.wikipedia.org/wiki/Centrifugal_compressor&quot; rel=&quot;nofollow&quot;&gt;centrifugal compressors&lt;/a&gt; for various reasons. In larger turbines they become impractical, but that wouldn't affect this application.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Centrifugal_fan&quot; rel=&quot;nofollow&quot;&gt;centrifugal fan&lt;/a&gt; causes the air flow to turn 90 degrees. In computers this can be good, mounted above a heat sink, where they draw air through the heat sink, and then sideways out the exhaust (or sometimes vice versa). Efficiency is not as important. In your application, the aim of the propulsion system is to increase the air velocity versus the air moving past the plane. The fan is making the air turn 90 degrees to come into the fan intake, and then 90 degrees back to exit the exhaust.  The turns in the air flow will introduce losses in the flow, and it's much easier to make smooth flow in and out of an axial fan than a centrifugal fan in this case. A centrifugal fan can also be a heavier installation than an axial fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, one fan will probably be more efficient than two, because you would be adding weight for the installation parts, wiring, etc., of the second engine, and not gaining much unless you really need the power of a second engine, or have some redundancy/configuration requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think an intake on top of the fuselage would hurt performance more than help it. By disrupting the air flow, it would probably cause more reduction in lift and increase in drag than the low pressure intake would benefit it. Having an intake more like the one in the above picture that just feeds a centrifugal fan rather than an axial one would probably be a better option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having one exhaust will probably be a more simple design. Guide vanes or even a vectored exhaust steer the exhaust better if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from the issues in the integration:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://www.engineeringtoolbox.com/fan-types-d_142.html&quot; rel=&quot;nofollow&quot;&gt;comparison&lt;/a&gt; of various parameters for axial vs. centrifugal fans. The backward-inclined flat blade configuration shows a graph that is actually relatively similar to the axial fans, aside from the power curve. Als, here are a couple interesting summaries of &lt;a href=&quot;http://www.aerovent.com/docs/fan-engineering-topics/fan-performance-characteristics-of-axial-fans---fe-2300.pdf&quot; rel=&quot;nofollow&quot;&gt;axial fans&lt;/a&gt; and &lt;a href=&quot;http://www.aerovent.com/docs/fan-engineering-topics/fan-performance-characteristics-of-centrifugal-fans---fe-2400.pdf&quot; rel=&quot;nofollow&quot;&gt;centrifugal fans&lt;/a&gt;. They have a more industrial focus, but still have some relevance.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-02T17:49:11.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8440" PostTypeId="2" ParentId="8432" CreationDate="2014-09-02T19:25:23.467" Score="12" Body="&lt;p&gt;As pointed out by Farhan, it adds redundancy to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 747 once &lt;a href=&quot;https://en.wikipedia.org/wiki/Northwest_Airlines_Flight_85&quot; rel=&quot;noreferrer&quot;&gt;experienced a rudder hard over&lt;/a&gt;. Even with the split rudder design, the crew had to rely on asymmetrical thrust to control the aircraft. If it had one very large rudder surface, control would be much more difficult, or may even be impossible.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="65" LastEditDate="2015-07-02T14:24:45.343" LastActivityDate="2015-07-02T14:24:45.343" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8441" PostTypeId="1" AcceptedAnswerId="8444" CreationDate="2014-09-02T19:37:04.927" Score="12" ViewCount="5962" Body="&lt;p&gt;In an airliner, where does the APU draw its intake air?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a similar location for all airliners, or do different options exist?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="3151" LastEditDate="2014-09-03T14:01:41.097" LastActivityDate="2015-01-30T23:27:01.963" Title="Where does the APU draw its intake air?" Tags="&lt;apu&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8442" PostTypeId="2" ParentId="8438" CreationDate="2014-09-02T19:41:09.140" Score="9" Body="&lt;p&gt;Interesting question, and I can only answer in general terms because much depends on speculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;use one central exhaust&lt;/li&gt;&#xA;&lt;li&gt;one big blower is better than two small ones&lt;/li&gt;&#xA;&lt;li&gt;one short flow channel is better than two long ones&lt;/li&gt;&#xA;&lt;li&gt;suction on top might be beneficial for high lift&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Radial-flow compressors are very light and achieve high pressure gains per stage. However, the simple plastic thing in your illustration will not have good efficiency. Generally, cambered blades are better than straight blades, and the thinner they are the better. Thick blades block more of the flow path. The drawback is their high diameter, and by placing the blower on its side, you get around this obstacle in an elegant way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea of using two exhausts complicates things; if you use a single one, you can avoid problems due to unsymmetrical thrust. Given that the compressor runs in one of two directions, asymmetries will be very hard to avoid. By placing vanes into the exhaust you can actually give the model plane some degree of sideways thrust vectoring. Also, two flow channels will have more surface area per cross section than a single channel. Your losses will be higher if you use two like in the illustration because they are longer than necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same goes for the blower: A single, larger one will always be more efficient. The gap size in a small blower is probably relatively bigger than that of a larger blower, and gaps are real efficiency killers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another efficiency killer is flow separation in the ducts. Make sure that cross section changes are gradual and avoid bending the flow as much as possible. It will probably help if you install cambered guide vanes at the entry of the exhaust to convince the rotational flow to change direction and leave the round compressor chamber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suction on top is also interesting. There have been &lt;a href=&quot;http://history.nasa.gov/SP-367/chapt4.htm#f67&quot;&gt;many ideas&lt;/a&gt; about &lt;a href=&quot;http://en.wikipedia.org/wiki/Boundary_layer_suction&quot;&gt;boundary layer suction&lt;/a&gt; to increase maximum lift, and your turbine inlet will certainly help to remove some of the boundary layer where it will separate first. Normally, turbine intakes are placed where the normal flow field already shows some pressure increase due to ram effects, but at the speed of a model airplane this will not be a factor. I expect the best intake in your case is a hole on top of the aircraft with nicely rounded edges. Those rounded edges should already produce some lift, and the whole configuration will probably achieve a higher stall angle of attack when the engine runs at full power than at idle power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only speculate how much power will be converted to thrust, but I bet placing an ordinary propeller at the usual place will be more efficient. But the configuration you propose has its own merits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-02T19:41:09.140" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8443" PostTypeId="2" ParentId="8441" CreationDate="2014-09-02T19:48:19.080" Score="1" Body="&lt;p&gt;The specific location varies a bit with each aircraft, but in general, they are located close to the APU - so in the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many aircraft will have a door on the top of the fuselage that opens when the APU is running, while others have an inlet that is always open, like on the 737.&lt;/p&gt;&#xA;" OwnerUserId="2179" LastActivityDate="2014-09-02T19:48:19.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8444" PostTypeId="2" ParentId="8441" CreationDate="2014-09-02T19:48:52.673" Score="16" Body="&lt;p&gt;The APU is usually located at the rear of the aircraft, in the tail, so the intake is generally somewhere on the side of this location. Aircraft place the inlet in different places though, and some even put the APU somewhere different. For some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xw2RB.jpg&quot; alt=&quot;737 APU Inlet&quot;&gt;&lt;br&gt;&#xA;737 intake, the small &lt;a href=&quot;http://en.wikipedia.org/wiki/NACA_duct&quot; rel=&quot;noreferrer&quot;&gt;NACA inlet&lt;/a&gt; at the bottom&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://training.deicinginnovations.com/wp-content/gallery/apu/e145-apu-intake-exhaust.jpg&quot; rel=&quot;noreferrer&quot;&gt;E145&lt;/a&gt; (the place they don't want you to put de-icing fluid)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://c2.staticflickr.com/4/3025/3071008355_8b8546d350_z.jpg&quot; rel=&quot;noreferrer&quot;&gt;B777&lt;/a&gt; (the scoop that opens upwards)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://i337.photobucket.com/albums/n385/motidog/A330apu2.jpg&quot; rel=&quot;noreferrer&quot;&gt;A330&lt;/a&gt; (a scoop on the underside of the tail)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://i183.photobucket.com/albums/x312/CAPFlyer/727/P7120048.jpg&quot; rel=&quot;noreferrer&quot;&gt;B727&lt;/a&gt; (inside of the wheel well)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/222356&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; is an interesting thread including other examples.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-30T23:27:01.963" LastActivityDate="2015-01-30T23:27:01.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8445" PostTypeId="2" ParentId="8428" CreationDate="2014-09-02T20:12:49.363" Score="9" Body="&lt;p&gt;The autopilot controls hydraulic actuator that is connected to the control link at some point. Since power transfer in the link is bidirectional, the control column moves when autopilot operates it. The same goes for thrust levers operated by autothrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot fights it, the autopilot will increase the force applied up to some limit at which it will disconnect. It can't really recognize whether the force is from the pilot or due to aerodynamic forces, but that's all right, because it should disconnect both if the pilot tries to yank the controls and when keeping the plane in the selected attitude requires too large control input (e.g. hard up elevator because the plane is too slow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing aircraft maintains this behaviour even on models with fly-by-wire (B777 and B787). Airbus did remove the feedback, because the command given does not directly correspond to control surface position anyway. So far I believe the only other civilian aircraft without feedback is Sukhoi Su-100.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-02T20:12:49.363" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8446" PostTypeId="2" ParentId="2581" CreationDate="2014-09-02T20:52:31.950" Score="3" Body="&lt;p&gt;I noticed that someone in the comments had asked about the U.S., too. &lt;a href=&quot;http://www.deltamuseum.org/&quot; rel=&quot;nofollow&quot;&gt;Delta's aviation museum in Atlanta&lt;/a&gt; does offer the ability to rent an hour in an old 737-200 simulator. This is a full-motion pilot-training simulator. &lt;a href=&quot;http://www.deltamuseum.org/exhibits&quot; rel=&quot;nofollow&quot;&gt;Their website&lt;/a&gt; claims that it's the only one open to the public in the U.S. It costs about $400 USD for an hour.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-09-02T20:52:31.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8447" PostTypeId="1" AcceptedAnswerId="8457" CreationDate="2014-09-03T01:10:11.163" Score="14" ViewCount="1865" Body="&lt;p&gt;The graph on page 17 (PDF page 18) of &lt;a href=&quot;http://www.boeing.com/news/techissues/pdf/statsum.pdf&quot;&gt;this Boeing air safety publication&lt;/a&gt; shows the fatal accident rate for commercial jets in the US and Canada dropped from about 40 per million departures in 1959 to 2 per million departures in 1962.  Since then, the rate has declined even further, but nothing as dramatic as the original drop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happened during the the 1959-1962 period to so greatly reduce the accident rate?&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2016-12-23T19:07:29.787" Title="Airline safety: what happened between 1959 and 1962?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;aviation-history&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8448" PostTypeId="2" ParentId="2581" CreationDate="2014-09-03T05:40:13.363" Score="1" Body="&lt;p&gt;British Airways' flight training program provides public access to their &lt;a href=&quot;http://www.britishairways.com/en-gb/baft/fly-a-simulator/fly-a-simulator-public/fly-a-simulator-public&quot; rel=&quot;nofollow&quot;&gt;full motion simulators&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can book a &lt;a href=&quot;http://www.britishairways.com/en-gb/baft/fly-a-simulator/fly-a-simulator-public/booking-your-experience/booking-your-experience&quot; rel=&quot;nofollow&quot;&gt;one hour training session&lt;/a&gt; in their 737-400 simulator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, well worth the money, since its a professional and I stress again &lt;strong&gt;full motion simulator&lt;/strong&gt;. In fact, its the same one BA uses to train their own pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are located in &lt;a href=&quot;https://www.britishairways.com/en-fr/baft/our-location/our-location&quot; rel=&quot;nofollow&quot;&gt;Cranebank&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="65" LastEditDate="2015-02-25T15:02:55.963" LastActivityDate="2015-02-25T15:02:55.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8449" PostTypeId="1" AcceptedAnswerId="8450" CreationDate="2014-09-03T08:51:37.877" Score="19" ViewCount="4948" Body="&lt;p&gt;I know there are planes whose APU (&lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;Auxiliary Power Unit&lt;/a&gt;) is located elsewhere, but for the most common commercial jet aircraft (A320, B737, B747, A330,...), the APU is located in the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a good reason for that (place, weight, airflow,...)?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="23223" LastEditDate="2019-08-07T09:14:02.777" LastActivityDate="2019-08-07T09:14:02.777" Title="Why is the APU located in the tail for almost all commercial aircraft?" Tags="&lt;aircraft-design&gt;&lt;apu&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8450" PostTypeId="2" ParentId="8449" CreationDate="2014-09-03T09:03:28.963" Score="32" Body="&lt;p&gt;Dead space... Not much room in the tail to put other stuff, and it fits. Plus it has a nice empty space just outside for the exhaust pipe to exit without the hot gasses hitting anything.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Put the APU in the nose and you need a long pipe somewhere to get rid of the exhaust. More weight, more space, etc.&lt;br/&gt;&#xA;Put it in the wing and you're looking at uneven weight distribution (you want it at or near the centerline).&lt;br/&gt;&#xA;Leaves the tail area as a logical place, and there just happens to be space there as well in most aircraft.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-09-03T09:03:28.963" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8451" PostTypeId="1" CreationDate="2014-09-03T09:04:31.680" Score="0" ViewCount="95" Body="&lt;p&gt;Suppose that one points a laser beam to the sky, constantly (so that an aircraft have to deal with it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could that beam cause any trouble to that aircraft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would that individual need to obtain some sort of authorization? &lt;/p&gt;&#xA;" OwnerUserId="3408" LastEditorUserId="2176" LastEditDate="2015-06-12T16:57:58.330" LastActivityDate="2015-06-12T16:57:58.330" Title="Laser projection on the sky" Tags="&lt;safety&gt;&lt;laser-illumination&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2014-09-03T11:09:03.023" ContentLicense="CC BY-SA 3.0" />
  <row Id="8452" PostTypeId="2" ParentId="8447" CreationDate="2014-09-03T09:53:46.927" Score="4" Body="&lt;p&gt;No doubt, prima facie what's most pertinent needs to be stated at the outset. &lt;strong&gt;There is an element of randomness to all air crashes.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, sustained efforts by US and some foreign airlines to identify and eliminate minor problems that generally are common precursors to accidents brought down fatality rate drastically from the '60s onwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most common scenarios for a plane crash in the '50s was &lt;strong&gt;Controlled Flight Into Terrain&lt;/strong&gt;(CFIT) referring to aircraft that were piloted into the ground, water, mountains or other terrain. However, &lt;strong&gt;improvements in cockpit instruments and jet engines dramatically improved aircraft performance and brought down the number of CFITs in the early '60s&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at the number of air crashes in &lt;a href=&quot;http://www.planecrashinfo.com/1959/1959.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;1959&lt;/a&gt;, &lt;a href=&quot;http://www.planecrashinfo.com/1960/1960.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;1960&lt;/a&gt;, &lt;a href=&quot;http://www.planecrashinfo.com/1961/1961.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;1961&lt;/a&gt;, &lt;a href=&quot;http://www.planecrashinfo.com/1962/1962.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;1962&lt;/a&gt;. The number of air crashes in the US fell from around sixteen in 1959 to around four in 1962. (Check above link for exact figures.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, &lt;strong&gt;every single air crash that was successfully investigated provided data to the OEMs that was used to improve the aircraft&lt;/strong&gt;. For example, the public inquiry into the Comet airliner disaster in 1954 found out that &quot;Metal Fatigue&quot; was the cause of the accident. The investigators found that a small weakness such as this would quickly deteriorate under pressure, and would rapidly lead to a sudden and general break-up of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://news.bbc.co.uk/onthisday/hi/dates/stories/october/19/newsid_3112000/3112466.stm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://news.bbc.co.uk/onthisday/hi/dates/stories/october/19/newsid_3112000/3112466.stm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at this image below. It reflects the causes of air accidents: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yGMCF.jpg&quot; alt=&quot;Accident Statistics&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice that some of the major causes of air accidents like Pilot Error and Mechanical Failure have gone down between the '50s and '60s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.planecrashinfo.com/cause.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.planecrashinfo.com/cause.htm&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.thepoliticalindian.com/plane-crash-reasons-since-1950/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.thepoliticalindian.com/plane-crash-reasons-since-1950/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lessons were learnt from past accidents. Consequently, companies like Boeing brought about necessary improvements to the avionics and engines. Airliners also helped pilots hone their skills. A combination of these two factors brought down the number of air crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even to this day, OEMs and airlines are making effort to further improve flight safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One oft-cited example is a discovery in the last decade by US Airways (then US Air) that many of its planes approaching Charlotte/Douglas International Airport in North Carolina were coming in “high and hot” - too fast and at a steep angle. After the investigation into this issue was completed, the FAA changed the approach procedure there and the airport installed a system to guide planes at a proper angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/safety/safety-recs/recletters/A-13-024.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.ntsb.gov/safety/safety-recs/recletters/A-13-024.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3386" LastEditDate="2016-12-23T19:07:29.787" LastActivityDate="2016-12-23T19:07:29.787" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8453" PostTypeId="2" ParentId="8416" CreationDate="2014-09-03T14:13:21.820" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.flightradar24.com&quot; rel=&quot;nofollow&quot;&gt;flightradar24&lt;/a&gt; takes as input mainly ADS-B data, as explained &lt;a href=&quot;http://www.flightradar24.com/how-it-works/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. It seems to be enough to know scheduled departure and arrival time, departure and arrival airport, registration number and some extra pieces of data you may not need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For technical failure, you may see the &lt;a href=&quot;http://avherald.com/&quot; rel=&quot;nofollow&quot;&gt;aviation herald website&lt;/a&gt; (I don't know how to access ACARS messages)&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2014-09-03T14:13:21.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8454" PostTypeId="2" ParentId="8449" CreationDate="2014-09-03T15:15:08.143" Score="24" Body="&lt;p&gt;There are a few reasons that the APU is located in the tail in most modern aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As previously mentioned, the space in the tail is otherwise mostly unused. Aside from hydraulics and such for the control surfaces, there isn't much use for the space. Most aircraft don't have any other spaces like that. Alternate locations like the wing root are generally used for fuel tanks, landing gear, air conditioning packs, and other systems. This area is also outside the pressure vessel, which reduces the number of ducts and such that need to pass through the pressure vessel wall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important benefit is fire protection. Having the APU in the tail places it as far away from the cabin and fuel tanks as possible, and being outside the pressure vessel makes it easier to isolate from those areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the exhaust exit the tail prevents it from interfering with any other parts of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not having it next to anything else also makes it easier to access for maintenance, generally through doors on the underside of the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drawbacks of having the APU in the tail include the need to run bleed ducts, fuel lines, and power supply wiring all the way back there. Also, the hydraulics and controls in the tail must be protected in case of a problem with the APU.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-03T15:15:08.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8455" PostTypeId="2" ParentId="8447" CreationDate="2014-09-03T15:48:36.987" Score="-2" Body="&lt;p&gt;When you are looking at &quot;per capita&quot; style numbers you also have to look at the overall volume in your population. Given that the time period is the general start of the growth of aviation, I'm going to guess that you would find that overall flights (and passengers, miles, etc, etc) &lt;em&gt;increased&lt;/em&gt; during the same period. That would make the &quot;per X&quot; number of virtually anything you look at in aviation improve. &lt;/p&gt;&#xA;" OwnerUserId="3410" LastActivityDate="2014-09-03T15:48:36.987" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8456" PostTypeId="1" AcceptedAnswerId="8458" CreationDate="2014-09-03T17:01:39.970" Score="6" ViewCount="1346" Body="&lt;p&gt;Every job in every industry has some &quot;pressure&quot;, &quot;stress&quot;, or &quot;burdens&quot; for that job. Being a PPL feels free, but I'm paying for flying. Working as a pilot, I get paid for flying. BUT, before I decide I want to join this industry, what are the burdens that an airline pilot has to face routinely? Does it vary if you're working for a small regional airline vs major international airlines?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1696" LastEditDate="2015-03-14T01:38:41.447" LastActivityDate="2015-03-14T01:38:41.447" Title="Burdens of working as an airline pilot" Tags="&lt;career&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2014-09-09T21:28:15.713" ContentLicense="CC BY-SA 3.0" />
  <row Id="8457" PostTypeId="2" ParentId="8447" CreationDate="2014-09-03T18:37:02.837" Score="8" Body="&lt;p&gt;I believe the answer has something to do with the introduction of the passenger jet airliner, which first came into service in the late 1950s.  Note please that the original poster is asking for information on &quot;commercial jets&quot; whereas the statistics that others have offered have information on commercial planes in general, including prop planes.  I glanced at the statistics for 1959 presented above and there were only two passenger jets (including one KC-135, which you may discount if you like) that crashed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this to the statistics presented for 1962.  There were six or seven crashes of Boeing and Douglas jet airliners.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me this means the differences were in all probablility not statistically significant.  We don't have enough &quot;samples&quot; to reach a valid conclusion.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you can see is a general explosion in the number of people flying.  Jets really introduced the public to flying.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-09-03T18:37:02.837" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8458" PostTypeId="2" ParentId="8456" CreationDate="2014-09-03T20:02:43.187" Score="3" Body="&lt;p&gt;&lt;em&gt;This is a very broad topic and is heavily opinion based.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vast majority of commercial pilots do love flying and that's the reason they go through the &lt;em&gt;abuse&lt;/em&gt; by airlines. &lt;strong&gt;All&lt;/strong&gt; GA pilots also love flying but either cannot afford the abuse or don't have time for it, so they just pay to satisfy this hobby.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question, some of the burdens are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High costs of training&lt;/li&gt;&#xA;&lt;li&gt;Waiting a long time (2 years or more on occasions) before getting hired by an airline&lt;/li&gt;&#xA;&lt;li&gt;Very low salaries in the beginning (several years)&lt;/li&gt;&#xA;&lt;li&gt;Losing seniority (very often) when you go to another carrier&lt;/li&gt;&#xA;&lt;li&gt;Staying away from home a lot&lt;/li&gt;&#xA;&lt;li&gt;Very unstable industry&lt;/li&gt;&#xA;&lt;li&gt;Many pilots eventually get bored and frustrated (regardless of initial enthusiasm)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Having said that, there are many many great benefits, too. The bottom line is that people only get into this career if they love it deeply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question you have to ask yourself is: &lt;em&gt;Am I willing to undergo this trouble for my passion?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P.S.:&lt;/strong&gt; The above holds true for the airlines and pilots in the US.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="938" LastEditDate="2014-09-09T09:08:49.037" LastActivityDate="2014-09-09T09:08:49.037" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8459" PostTypeId="2" ParentId="3842" CreationDate="2014-09-03T22:03:48.270" Score="1" Body="&lt;p&gt;I remember having read that in these airplanes, at high speeds and low angle of attack, it was the center section, the lifting fuselage, that provided most lift, but at an steeper attitude, it was the regular wing that lifted. The shape of the 'lifting fuselage' sides makes suspect an increased 'marginal vortex' drag, this reducing the efficiency of idea. For a new procedure to be added to series, at least in the Automotive industry, they say it must provide a 10% increase in efficiency, along with a 10% reduction in costs, this is why changes that a private owner can introduce in their engines or vehicles may be worth for them but not for a company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mail boxes open to suggestions by people in the production lines, that once received concepts such as the way to use a single screw or bolt instead of the several previously used, saving the cost of thousands of bolts a year, are closed now, changes in the production line for this minimalist improvements were too expensive to implement in recent times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides this, a patented idea must offer an overwhelming advantage for a builder to pay for it and incorporate to their production, if improvement is not big enough as to offer noticeable gains from the patent, the time will be left flowing, when the patents have expired, in most cases advances in technology offer better things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some XXI century airplane designs incorporate concepts analog to the Louis de Monge and Burnelli's lifting fuselages. The time will say if it are good enough. Salut +&lt;/p&gt;&#xA;" OwnerUserId="3414" LastActivityDate="2014-09-03T22:03:48.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8460" PostTypeId="1" AcceptedAnswerId="8461" CreationDate="2014-09-04T02:58:12.593" Score="2" ViewCount="4129" Body="&lt;p&gt;From the question about &lt;a href=&quot;https://aviation.stackexchange.com/q/7955/567&quot;&gt;sharp pods under airliner wings&lt;/a&gt;, I think the right term is anti-shock bodies, or flap actuators/track fairings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the little antenna looking thing extending off the rear end of it? My best guess it something anti-static? Why are they necessary?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2fjos.jpg&quot; alt=&quot;Airbus 321 wing close-up&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I should add that this is an American Airlines Airbus 321.&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-11-20T14:03:44.687" Title="Antennas on airliner wings?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;wing&gt;&lt;airbus&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2014-09-04T06:18:39.853" ContentLicense="CC BY-SA 3.0" />
  <row Id="8461" PostTypeId="2" ParentId="8460" CreationDate="2014-09-04T03:42:22.830" Score="5" Body="&lt;p&gt;You're very right. It's a &lt;a href=&quot;http://en.wikipedia.org/wiki/Static_discharger&quot;&gt;static discharger&lt;/a&gt; or &quot;static wick&quot;, and it is used to dissipate the static electricity accumulated during flight. The electrical buildup happens during flight through precipitation, clouds, dust, etc., and is known as &quot;precipitation static&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the static reaches a certain point, it will discharge. Without wicks, this happens through antennae and can really mess with communications or navigation. Wicks make sure that process doesn't cause problems. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-09-04T03:42:22.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8462" PostTypeId="1" CreationDate="2014-09-04T09:25:32.360" Score="10" ViewCount="6413" Body="&lt;p&gt;I've heard of ETOPS, which permits the maximum duration for which a two-engined airplane can fly on one engine to the nearest airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are 4-engined planes such as the Boeing 747 and Airbus A380 subject to any equivalent rules? If not, can these planes safely fly on just one engine for as long as needed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, how are aircraft given different ETOPS certifications? What makes the 787 get ETOPS-330 and the 767 only ETOPS-180 despite the similarity in range and (to an extent) engine power and design?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="504" LastEditDate="2014-09-04T10:06:03.437" LastActivityDate="2015-12-17T23:31:39.220" Title="Are four-engined airplanes subject to ETOPS equivalent rules?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;airline-operations&gt;&lt;etops&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8463" PostTypeId="1" CreationDate="2014-09-04T10:51:59.857" Score="8" ViewCount="1605" Body="&lt;p&gt;I just found out that there is an airport in Disneyland Paris with the IATA code DLP. Since I've never heard of it, I wanted to see it on Google Maps, but haven't found it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there actually an airport, and where?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does Disneyland has its own, with CDG not far away?&lt;/p&gt;&#xA;" OwnerUserId="3421" LastEditorUserId="1467" LastEditDate="2017-04-05T06:44:40.660" LastActivityDate="2019-12-04T18:42:34.780" Title="Where is the airport in Disneyland Paris? (DLP)" Tags="&lt;airport&gt;&lt;france&gt;" AnswerCount="4" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8464" PostTypeId="2" ParentId="8463" CreationDate="2014-09-04T11:10:43.147" Score="15" Body="&lt;p&gt;IATA codes don't necessarily correspond to airports. Some non-airports have IATA codes to allow airlines to sell through tickets that might, for example, consist of travelling from A to&amp;nbsp;B by plane and then onward from B to&amp;nbsp;C by train. DLP isn't on &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_IATA-indexed_railway_stations&quot;&gt;Wikipedia's list of railway stations with IATA codes&lt;/a&gt; but I imagine something very similar is going on here.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-09-04T11:10:43.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8465" PostTypeId="2" ParentId="8462" CreationDate="2014-09-04T11:31:02.817" Score="2" Body="&lt;p&gt;Other way round - the multi-engine rules existed long before ETOPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no 747 pilot will continue as scheduled on one engine. If you are having enough problems that you lose 75% of your power you will punch &quot;Nearest&quot; on the navi and go there.&lt;/p&gt;&#xA;" OwnerUserId="2590" LastActivityDate="2014-09-04T11:31:02.817" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8466" PostTypeId="2" ParentId="8463" CreationDate="2014-09-04T11:35:12.403" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there actually an airport, and where?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Disneyland does not have an airport in Paris,France.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disneyland, Paris is situated approximately 20 miles from Paris.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a direct Shuttle Bus Airport Transfer to Disneyland from &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) Charles de Gaulle,&#xA;(b) Orly and &#xA;(c) Beauvais airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://vea-shuttle.co.uk/&quot; rel=&quot;nofollow&quot;&gt;http://vea-shuttle.co.uk/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I wanted to see it on Google Maps, but haven't found it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Please check the Google Map here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airportia.com/france/disneyland-paris-airport/map/&quot; rel=&quot;nofollow&quot;&gt;http://www.airportia.com/france/disneyland-paris-airport/map/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-09-04T11:35:12.403" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8467" PostTypeId="2" ParentId="8462" CreationDate="2014-09-04T15:07:19.650" Score="9" Body="&lt;p&gt;Yes, three- and four-engine airliners follow 'Long-Range Operations' restrictions just like twin-engine airliners.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;noreferrer&quot;&gt;WikiPedia&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Airbus proposed to replace ETOPS by a newer system, referred to as &lt;strong&gt;LROPS&lt;/strong&gt; or Long Range Operational Performance Standards, which would affect all civil airliners, not just those with a twin-engine configuration&lt;/p&gt;&#xA;&lt;p&gt;(...)&lt;/p&gt;&#xA;&lt;p&gt;The FAA has decided to use the single term, 'extended operations,' or ETOPS, for all affected operations regardless of the number of engines on the airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The large 4-engined airliners can not reliably fly long distances on one engine only.  But  they &lt;strong&gt;can&lt;/strong&gt; fly on three engines just fine.  When only two engines are available they divert to the nearest airport.&lt;/p&gt;&#xA;&lt;p&gt;The ETOPS rules become relevant whenever a three- or four-engined jet diverts more than 180 minutes from the nearest airport.&lt;/p&gt;&#xA;&lt;p&gt;For more information, refer to the airliners.net thread on &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/269589/&quot; rel=&quot;noreferrer&quot;&gt;3 And 4 Engine Planes Requiring Etops&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-17T23:31:39.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8469" PostTypeId="1" CreationDate="2014-09-04T23:19:50.230" Score="1" ViewCount="846" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cxvt1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am making a project related to flight paths. If we are given two points in space (lat,long) and the flight headings(angles) that the flight should attain at that points. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By using the radius of turn formula, I checked whether the flight can reach the next point or not, but how can I check whether the flight can reach both the points with the specified heading or not??&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please help me out.. Thanks in advance...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for the ambiguity in the question. In the figure attached, if I need to go through points 1, 2 and 3 so on which are few points in the flight path. And if I am given (lat,long,heading the flight should attain at that point) for each point, I need to find out whether points can be reached or not. Also please suggest me the solution if I need the same heading at all the three points (say x).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the flight should not take more than 1 turn i.e. loops are not allowed (flight should always move towards the destination).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YPPKd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, i need to head from source to destination along points 1,2,3 with same heading(q) at these three points. For example take q as the angle between source and destination. Now i want to move towards destination i.e by not turning back and no loops. Just want know whether its feasible for flight with specific radius of turn to reach the next point or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or what should the minimum vertical distance and horizontal distance between the points be in order to satisfy both the points.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Iy7sq.png&quot; alt=&quot;Figure 3&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But we can't determine the minimum radius exactly right?? In the figure 3, point 1 can be reached with the specified heading with distance below 2 * rmin. So the condition be like delta(x) &gt; rmin definitely because it can't reach close neighboring points but what should be next condition to check whether it can reach with required heading or not. If it is like delta(x) &gt; 2 * rmin then figure 3 would contradict it, right?&lt;/p&gt;&#xA;" OwnerUserId="3422" LastEditorUserId="3422" LastEditDate="2014-09-08T03:17:57.420" LastActivityDate="2014-09-08T07:20:22.553" Title="Radius of Turn Query" Tags="&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ClosedDate="2014-09-05T11:39:17.550" ContentLicense="CC BY-SA 3.0" />
  <row Id="8470" PostTypeId="2" ParentId="8469" CreationDate="2014-09-05T07:02:49.140" Score="2" Body="&lt;p&gt;The difference in headings gives you the number of degrees you need to turn. The distance between the two points then becomes a secant to the turning circle which should give you the turn radius by applying some basic geometry. I assume that the turn starts on point 1 and ends on reaching point 2. Like this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a2R8I.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Now you first need to calculate the turn radius, using the equation for secant length: Start with the difference between the two headings and call that angle &lt;span class=&quot;math-container&quot;&gt;$\varphi$&lt;/span&gt;. Then the difference between two points &lt;span class=&quot;math-container&quot;&gt;$s$&lt;/span&gt; is &lt;span class=&quot;math-container&quot;&gt;$$s = 2\cdot r \cdot sin\frac{\varphi}{2}$$&lt;/span&gt;&#xA;Since you know &lt;span class=&quot;math-container&quot;&gt;$s$&lt;/span&gt;, you can calculate the turn radius &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt; by a simple transformation: &lt;span class=&quot;math-container&quot;&gt;$$r = \frac{s}{2\cdot sin \frac{\varphi}{2}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Now you need to check whether the airplane will be able to turn with that radius. This depends on wing loading &lt;span class=&quot;math-container&quot;&gt;$\frac{m}{S}$&lt;/span&gt;, density of air &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; and maximum lift coefficient &lt;span class=&quot;math-container&quot;&gt;$c_{L_{max}}$&lt;/span&gt;, and the equation for the minimum turn radius is &lt;span class=&quot;math-container&quot;&gt;$$r_{min} = \frac{2\cdot m}{c_{L_{max}}\cdot S \cdot \rho}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Compare both values of &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt; and check if &lt;span class=&quot;math-container&quot;&gt;$r &amp;gt; r_{min}$&lt;/span&gt;. Then the turn is physically possible.&lt;/p&gt;&#xA;&lt;p&gt;Now I only hope that this is really what you asked. Your question leaves a lot of room for interpretation.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;EDIT: @amarender has updated the question. Now the heading is identical at all intermediate points, and below is one of many possible solutions (blue line):&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kEmcf.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;I indicated with pie segments where the turns are; of course, the one single turn condition has to be interpreted as one turn per intermediate point. The sections between the turns are straight, and all bring the aircraft closer to the destination if the heading at the intermediate points is identical to the heading from target to destination.&lt;/p&gt;&#xA;&lt;p&gt;When do we have a condition where a solution is not possible? Only if the points are too close together to satisfy the condition of the minimum turning radius. By rotating the coordinate system such that the desired heading at the points is parallel to the x axis, this is easier to show:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/C6fm8.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The distance between two points in the direction of the desired heading &lt;span class=&quot;math-container&quot;&gt;$\Delta x$&lt;/span&gt; must not be smaller than the diameter of the minimum possible circle (&lt;span class=&quot;math-container&quot;&gt;$2\cdot r_{min}$&lt;/span&gt;) using the equation above. The green line above is for &lt;span class=&quot;math-container&quot;&gt;$\Delta x &amp;gt; 2\cdot r_{min}$&lt;/span&gt;, and the red line for the boundary condition &lt;span class=&quot;math-container&quot;&gt;$\Delta x = 2\cdot r_{min}$&lt;/span&gt;. To be precise, the equation above does not put a limit on the maximum load factor &lt;span class=&quot;math-container&quot;&gt;$n_{z_{max}}$&lt;/span&gt; - if this needs to be considered, the minimum radius is:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$r_{min} = \frac{2\cdot \frac{n_{z_{max}}}{\sqrt{n^2_{z_{max}}-1}}}{c_{L_{max}}\cdot \frac{S}{m} \cdot \rho}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Things get more complicated when the heading at the points is different from the heading from the source to the destination. Then &lt;span class=&quot;math-container&quot;&gt;$\Delta y$&lt;/span&gt; becomes important as well, and when it gets large relatively to &lt;span class=&quot;math-container&quot;&gt;$\Delta x$&lt;/span&gt;, the straight connection between turns will point away from the target very soon.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-08T07:20:22.553" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8471" PostTypeId="1" AcceptedAnswerId="8472" CreationDate="2014-09-05T07:15:30.770" Score="51" ViewCount="52659" Body="&lt;p&gt;Before landing and taking off, I notice the lights inside commercial aircraft are greatly reduced. I don't buy the explanation of power saving in case full thrust is needed as nowaday lights don't need a lot of energy and the crew says we can use the smaller reading lamp to continue reading. I suppose this is something to do with security but I don't understand what.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3223" LastEditDate="2014-09-05T08:24:33.503" LastActivityDate="2020-06-01T14:35:20.200" Title="Why are the lights inside commercial airplanes turned off during take off and landing?" Tags="&lt;commercial-aviation&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8472" PostTypeId="2" ParentId="8471" CreationDate="2014-09-05T08:06:18.540" Score="72" Body="&lt;p&gt;This is for safety reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take-off and landing are the two most critical phases of flight and thus, every additional step to ensure survivability, be it even just adjusting the light, is taken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The interior lights or cabin lights are adjusted to match the exterior environment, so that in case of an emergency, especially if the interior lights fail, your eyes are already accustomed to the light setting and you do not require additional valuable seconds for adjustment to a possibly darker or brighter environment. The lights are usually adjusted at dusk, night or dawn to match the exterior environment.&lt;a href=&quot;http://gofar.aircanada.com/go-far-answers/question/cabin-lights-dimmed/&quot; rel=&quot;nofollow noreferrer&quot;&gt;1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the cabin lights do not fail during an emergency, the dimmed light also makes it easier to identify the &quot;EXIT&quot; signs which illuminate and make the guidance lighting on the floor easier to follow. The bright emergency lighting is more prominent to identify when the cabin light is dimmed, saving valuable seconds as the aircraft is evacuated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This also ties in with having to raise the blinds on the windows. The blinds need to be raised during take-off and landing irrespective of the outside light situation, however, with a darker cabin, any outside light source, especially from fires or other hazards is easier to identify by the crew, making the decision process of whether one side could be inappropriate to use for evacuation faster, e.g. fire on port side --&gt; no evacuation on that side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blinds are therefore raised to allow a better view for cabin crew of the outside area and external aircraft parts, such as engines, wings, etc.&#xA;See also this related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1536/why-open-up-the-window-shades-before-takeoff-and-landing&quot;&gt;Why open up the window shades before takeoff and landing?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="11215" LastEditDate="2020-06-01T14:35:20.200" LastActivityDate="2020-06-01T14:35:20.200" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="8473" PostTypeId="1" AcceptedAnswerId="8476" CreationDate="2014-09-05T08:43:22.067" Score="4" ViewCount="6793" Body="&lt;p&gt;Kindly guide me where can I get a reliable and updated airport Master API. The airport API should have all the information about all the airports in the world and I also want to know how much do they charge for the API.&lt;/p&gt;&#xA;" OwnerUserId="3423" LastEditorUserId="1961" LastEditDate="2014-09-06T11:29:39.933" LastActivityDate="2019-11-13T00:21:30.750" Title="Where can I get a reliable and a updated Airport API or Airport Database, and I also want to know the charges for the API?" Tags="&lt;airport&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ClosedDate="2019-11-13T16:02:50.057" ContentLicense="CC BY-SA 3.0" />
  <row Id="8476" PostTypeId="2" ParentId="8473" CreationDate="2014-09-05T10:58:51.597" Score="7" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Location Identifiers&lt;/strong&gt; &amp;amp; Airline Designators data files available with &lt;strong&gt;daily updates&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The perfect solution to feeding your coding database. These files (more information in right hand column) are available as a 12 month subscription or a one-time web download. For the subscription, you will be granted access to the password protected extranet site upon purchase where you can retrieve the data files update daily.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.iata.org/publications/Pages/coding.aspx&quot; rel=&quot;noreferrer&quot;&gt;http://www.iata.org/publications/Pages/coding.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-05T10:58:51.597" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8477" PostTypeId="2" ParentId="2699" CreationDate="2014-09-05T11:24:10.357" Score="7" Body="&lt;p&gt;The OBRM, PRAM, CAM are three memory cards, which hold aircraft related data and softwares and plugged into the FAP at botton. (You can see three slots).&#xA;The page shown in the picture is cabin status page, which is showing current status of aircraft namely Music, Lights, Doors, temeperature and lavatories.&lt;/p&gt;&#xA;" OwnerUserId="3425" LastEditorUserId="72" LastEditDate="2014-09-05T11:37:52.840" LastActivityDate="2014-09-05T11:37:52.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8478" PostTypeId="1" AcceptedAnswerId="8481" CreationDate="2014-09-05T16:00:25.580" Score="3" ViewCount="1263" Body="&lt;p&gt;Normally, friction between surfaces is affected by the materials. Can skin friction be reduced by a low friction material like Teflon? &lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="21" LastEditDate="2014-09-06T03:57:48.553" LastActivityDate="2016-06-29T10:31:57.667" Title="Is skin friction drag affected by material?" Tags="&lt;drag&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8479" PostTypeId="1" CreationDate="2014-09-05T16:31:34.990" Score="1" ViewCount="549" Body="&lt;p&gt;I would like to receive some answer or advice on how to create 360 panorama images.&#xA;My plan is to use Cessna or Helicopter.&lt;/p&gt;&#xA;" OwnerUserId="3435" LastEditorUserId="65" LastEditDate="2015-03-04T19:47:24.453" LastActivityDate="2015-03-04T19:47:24.453" Title="How can I take 360° panoramic pictures in an aircraft or helicopter?" Tags="&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="0" ClosedDate="2016-06-29T14:14:10.320" ContentLicense="CC BY-SA 3.0" />
  <row Id="8480" PostTypeId="2" ParentId="8471" CreationDate="2014-09-05T17:15:37.723" Score="-11" Body="&lt;p&gt;You better start believing in the explanation of power saving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find the reference, but there was an accident over 5 years ago in which a plane was taking off with many non-essential loads at or near maximum: air conditioning, galleys heating food, cabin lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One generator failed, and the system supposed to shed non-essential loads also failed. The remaining generator wasn't designed to stand so much load, so it failed too. Loss of power to essential loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since then, airliners take off almost simulating an electrical emergency. Reading lamps are a reasonable compromise because very few people actualy use them.&lt;/p&gt;&#xA;" OwnerUserId="747" LastActivityDate="2014-09-05T17:15:37.723" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8481" PostTypeId="2" ParentId="8478" CreationDate="2014-09-05T17:35:17.497" Score="6" Body="&lt;p&gt;Indirectly, yes. Friction goes up when dirt and smashed bugs accumulate on the wing. A low surface energy coating might well reduce their stickiness, so the wing collects less dirt and has less roughness. This is especially helpful when it helps to delay the transition from laminar to turbulent flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to delay that transition would be a soft surface which could help to dampen the characteristic &lt;a href=&quot;http://en.wikipedia.org/wiki/Tollmien%E2%80%93Schlichting_wave&quot; rel=&quot;noreferrer&quot;&gt;Tollmien-Schlichting&lt;/a&gt; oscillations from which the transition of boundary layer flow from laminar to turbulent springs. Accelerated flow is naturally damped (the amplitude decreases relatively to flow speed), so it stays laminar on a smooth wing. Once the damping turns negative (i.e. the oscillation is increasing), the turbulent transition is imminent. When the wing is not only smooth, but also soft and helps to dampen those Tollmien–Schlichting oscillations, even unaccelerated flow might stay laminar for longer, which again reduces friction drag. So far, I am unaware that this effect has been exploited successfully on an aircraft, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The friction between gaseous substances and solids is not affected by the surface energy of the solid, so a direct reduction in viscous drag due to a polytetrafluoroethylene coating will not happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I trust you know how drag depends on surface roughness. If not, please feel free to post another question.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-05T17:40:45.853" LastActivityDate="2014-09-05T17:40:45.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8482" PostTypeId="2" ParentId="8479" CreationDate="2014-09-05T18:33:22.087" Score="1" Body="&lt;p&gt;My advice would be an aircraft is a lousy tool for this - airplanes in particular.&lt;br&gt;&#xA;An aircraft is always moving - airplanes have to move in order for the wings to generate lift, and even a helicopter hovering is going to be moving based on wind, thermals, and downwash from its own rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Movement makes panoramic imaging difficult since a lot of the modern camera tricks we use to capture panoramic images &quot;in camera&quot; involve rotating the camera (think iPhone/Android &quot;panorama&quot; shots, or the old-school camera-on-a-stick systems used for film photography). With a fixed-wing aircraft that motion would cause misalignments that would make stitching the images together difficult (because the perspective would be changing between shots).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Difficult doesn't mean impossible though - It's been done on quadcopters (&lt;a href=&quot;http://tv.adobe.com/watch/take-flight-into-the-adobe-creative-cloud/creating-aerial-panoramas-from-gopro-hero-3-images/&quot; rel=&quot;nofollow&quot;&gt;Adobe even has a tutorial&lt;/a&gt; where they stitch together a panorama using GoPro camera images), and you could do the same thing with a camera mounted on a full-size helicopter.&lt;br&gt;&#xA;You could probably make it work for a fixed-wing aircraft too, but it would be better if you had a rotating camera mount (rotating the whole airplane would change the perspective, but flying very slow and spinning the camera reasonably fast you'll probably get usable images).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-09-05T18:33:22.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8483" PostTypeId="2" ParentId="8417" CreationDate="2014-09-05T22:18:52.657" Score="6" Body="&lt;p&gt;Long story short, there is no such thing and @jwenting's &lt;a href=&quot;https://aviation.stackexchange.com/questions/8417/what-is-a-russian-iata-code#comment14975_8417&quot;&gt;comment&lt;/a&gt; is almost certainly correct (see edit below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only Google hits for &quot;Russian IATA code&quot; (apart from this question) are a series of Wikipedia articles on Russian airports, either on &lt;a href=&quot;http://wikipedia.org&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia.org&lt;/a&gt; itself or on other sites that have obviously scraped Wikipedia for content. All the articles (well, the ones I checked anyway) were edited by the same user and they refer to &lt;a href=&quot;http://g-avia.ru/kody_gorodov_vseh_stran_&quot; rel=&quot;nofollow noreferrer&quot;&gt;the same page&lt;/a&gt; as a source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The table on that page has a column called &quot;IATA code&quot; which is actually empty for Tamchy. The code you mentioned is in another column called &quot;internal code&quot;, presumably that means it's a domestic code used only in Russia and comparable - as @jwenting said - to the many 3-character US codes that have no IATA equivalent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, the Wikipedia contributor invented something that doesn't really exist; even the quoted source doesn't refer to ИКУ as an &quot;IATA code&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; The Russian Wikipedia &lt;a href=&quot;https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D0%B4_%D0%B0%D1%8D%D1%80%D0%BE%D0%BF%D0%BE%D1%80%D1%82%D0%B0_%D0%98%D0%90%D0%A2%D0%90&quot; rel=&quot;nofollow noreferrer&quot;&gt;page on IATA codes&lt;/a&gt; goes into slightly more detail on the internal codes (translation from Google):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sometimes this system of codes called &quot;sirenovskoy&quot; (from the ticket&#xA;  reservation system &quot;Siren&quot;), but the name is historically incorrect -&#xA;  this coding system used before the appearance of &quot;Sirens&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article also confirms @jwenting's comment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Many small towns and airports in the former Soviet Union did not have&#xA;  the IATA code and have only internal code.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, that page doesn't say who manages the codes and it doesn't provide any 'official' sources either, just links to other pages that simply list the codes. A cursory search of the Russian ministry of transport website doesn't turn up anything, but someone who actually speaks Russian might have more luck than me :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-09-08T19:06:16.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8484" PostTypeId="1" AcceptedAnswerId="8500" CreationDate="2014-09-05T22:25:01.283" Score="14" ViewCount="2143" Body="&lt;p&gt;I've just started aerobatics training!  Unfortunately, my middle ear really messes with me, particularly during loops. Strangely, aileron rolls give me no trouble at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know from other experienced aerobatic pilots that you can get used to aerobatic flying, and my tolerance will build up over time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;strong&gt;is there anything I can do &lt;em&gt;on the ground&lt;/em&gt; in order to help build up my tolerance more quickly?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2016-04-24T21:27:28.250" Title="What can I do on the ground in order to help my body acclimate to aerobatics?" Tags="&lt;medical&gt;&lt;aerobatics&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8486" PostTypeId="1" AcceptedAnswerId="8507" CreationDate="2014-09-06T11:35:59.033" Score="9" ViewCount="1161" Body="&lt;p&gt;If a passenger becomes unruly and the captain decides to land and remove that passenger from the flight, how much does the passenger have to pay the airline for the cost? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, what are the reasons for flight crews to decide whether to divert or continue the flight?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="22726" LastEditDate="2019-02-16T04:30:28.150" LastActivityDate="2019-02-16T22:39:15.047" Title="How much compensation does an unruly passenger have to pay to an airline if the flight has to be diverted to remove them?" Tags="&lt;emergency&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8487" PostTypeId="2" ParentId="8471" CreationDate="2014-09-06T13:38:22.700" Score="13" Body="&lt;p&gt;My flight instructor told me that also, when taxiing at night (that is, before taking off or after landing), lights should be kept at a minimum as a courtesy to other pilots. A bright line of full lit cabin windows could distract or mask other dimmer lights like the taxiways blue ones.&lt;/p&gt;&#xA;" OwnerUserId="3442" LastActivityDate="2014-09-06T13:38:22.700" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8488" PostTypeId="1" AcceptedAnswerId="8489" CreationDate="2014-09-06T15:37:30.263" Score="23" ViewCount="2876" Body="&lt;p&gt;Why is the &quot;Dutch&quot; roll called so? When did this name enter common usage, and what is its origin? Please cite sources if possible!&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="22726" LastEditDate="2019-10-16T03:55:38.413" LastActivityDate="2019-10-16T03:55:38.413" Title="Why is the &quot;Dutch&quot; roll called so?" Tags="&lt;aviation-history&gt;&lt;terminology&gt;&lt;dutch-roll&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8489" PostTypeId="2" ParentId="8488" CreationDate="2014-09-06T19:06:39.973" Score="16" Body="&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The origin of the name Dutch roll is uncertain. However, it is likely that this term, describing a lateral asymmetric motion of an airplane, was borrowed from a reference to similar-appearing motion in ice skating. In 1916, aeronautical engineer Jerome C. Hunsaker published the following quote: &quot;Dutch roll – the third element in the [lateral] motion [of an airplane] is a yawing to the right and left, combined with rolling. The motion is oscillatory of period for 7 to 12 seconds, which may or may not be damped. The analogy to 'Dutch Roll' or 'Outer Edge' in ice skating is obvious.&quot; In 1916, Dutch Roll was the term used for skating repetitively to right and left (by analogy to the motion described for the aircraft) on the outer edge of one's skates. By 1916, the term had been imported from skating to aeronautical engineering, perhaps by Hunsaker himself. 1916 was only five years after G. H. Bryan did the first mathematics of lateral motion of aircraft in 1911.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sadly, this question is probably not answerable beyond what wikipedia has on this site (unless there is an English Major looking for a Ph.D. thesis. ;)&lt;/p&gt;&#xA;" OwnerUserId="3266" LastActivityDate="2014-09-06T19:06:39.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8490" PostTypeId="2" ParentId="8484" CreationDate="2014-09-06T19:13:52.307" Score="14" Body="&lt;p&gt;The way the Air Force introduces people to the disorienting effects of aerobatics on the ground is to put them into smoothly spinning chairs called &lt;a href=&quot;http://en.wikipedia.org/wiki/B%C3%A1r%C3%A1ny_chair&quot; rel=&quot;noreferrer&quot;&gt;Barany Chairs&lt;/a&gt;.  And it doesn't just involve spinning in one direction, but smoothly and gently changing directions repeatedly.  Since I never suffered from airsickness, I don't know what they do (i.e. do they blindfold you, are there more than one axis of motion, do you have to tilt and move your head, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While an actual Barany Chair may be expensive, you could perhaps accomplish the same with  a friend and a nice heavy office chair.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="13197" LastEditDate="2016-04-24T21:27:28.250" LastActivityDate="2016-04-24T21:27:28.250" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8491" PostTypeId="1" AcceptedAnswerId="8492" CreationDate="2014-09-07T03:24:06.867" Score="2" ViewCount="3968" Body="&lt;p&gt;This is with reference to a &lt;a href=&quot;http://timesofindia.indiatimes.com/india/Mystery-plane-gives-jitters-to-international-airliners-near-Mumbai/articleshow/41897554.cms&quot; rel=&quot;nofollow&quot;&gt;News Article&lt;/a&gt; that I read today. I find it scary that radars would not be able to detect an aircraft. Is it really possible? If yes, how can ATCs manage this situation?&lt;/p&gt;&#xA;" OwnerUserId="3446" LastActivityDate="2014-09-07T13:44:14.970" Title="Can radars detect all planes, including military ones?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8492" PostTypeId="2" ParentId="8491" CreationDate="2014-09-07T05:20:04.423" Score="6" Body="&lt;p&gt;Some military aircraft reflect little enough radar energy to be effectively undetectable. Note that the actual details are likely classified, but even the modern F-22 still has a radar cross-section of &lt;a href=&quot;http://www.f-16.net/f-22-news-article3275.html&quot;&gt;about the size of a steel marble&lt;/a&gt;. Still, the B-2, an older stealth aircraft, is claimed to &lt;a href=&quot;http://www.airspacemag.com/military-aviation/the-stealth-bomber-elite-315558/?all&quot;&gt;disappear from air traffic radar when in stealth mode&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same article on the B-2 also notes that it has &lt;a href=&quot;http://www.airspacemag.com/military-aviation/the-stealth-bomber-elite-315558/?all&quot;&gt;&quot;deployable radio antennas for navigation in civilian skies&quot;&lt;/a&gt;. When flying during peacetime and outside of an MOA, military aircraft generally have some level of coordination with ATC. If the pilots of a stealth aircraft don't want to be seen, then presumably they would be responsible for maintaining separation from other aircraft, as they cannot be tracked on radar. Of course, there's also plenty of airspace where aircraft don't need to talk to ATC at all (E and G in the US), and the pilot of each aircraft is responsible for maintaining separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there are some things in this article that are unclear:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Etihad aircraft received a TCAS alert for an aircraft that didn't show up for ATC. TCAS intentionally uses the same frequencies and signalling as ground-based secondary radar, so if an aircraft receives a TCAS response it should also show up for ATC. The article does note that the aircraft were &quot;&lt;a href=&quot;http://timesofindia.indiatimes.com/india/Mystery-plane-gives-jitters-to-international-airliners-near-Mumbai/articleshow/41897554.cms&quot;&gt;450 to 480km from Mumbai's coastline&lt;/a&gt;&quot;, so it's possible that the mystery aircraft just had a weaker TCAS response that wasn't received by a distant ground-based receiver.&lt;/li&gt;&#xA;&lt;li&gt;The article suggests that fighter aircraft don't fly as high as 36,500 feet. A ground attack aircraft might not be able to fly that high, but most, if not all, air superiority fighters have service ceilings of at least 50,000 feet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="136" LastActivityDate="2014-09-07T05:20:04.423" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8493" PostTypeId="2" ParentId="8318" CreationDate="2014-09-07T07:46:13.790" Score="0" Body="&lt;p&gt;There are probably more incidents with propeller aircraft for a few reasons.  First jet pilots in the USA will have more experience (I concur with other posts that experience is a primary factor in this case).  Certainly, propeller aircraft have limitations when compared to jet aircraft (less power).  However, kept within their capabilities, propeller training aircraft are very safe.  I would expect any pilot to agree that a small Cessna will more readily glide than jet aircraft.  This learning to take off and land in a prop helps the student pilot get a feel for flying- a feel for the fluid force of air over the wings, nose, and tail.  &lt;/p&gt;&#xA;" OwnerUserId="3447" LastActivityDate="2014-09-07T07:46:13.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8494" PostTypeId="2" ParentId="8491" CreationDate="2014-09-07T13:44:14.970" Score="4" Body="&lt;p&gt;This is possible, and actually fairly common and expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Primary radars, as you most likely know, works by picking up reflected EM waves from an object. But many people do not realize that in engineering (as opposed to science), &lt;strong&gt;things are never perfect&lt;/strong&gt;. Radars &lt;em&gt;always&lt;/em&gt; pick up &quot;ghost images&quot;, caused by reflections of clouds in the atmosphere, a vessel, terrain etc. I've yet to seen a &lt;em&gt;raw&lt;/em&gt; radar image that has absolutely zero noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, in reality a plane is not a infinite small point in space, but a large object which reflects a certain amount of rays. These rays form a &quot;patch&quot; on the scope, and depending on the plane's orientation, this &quot;patch&quot; varies a lot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this sounds abstract, think of recording with a microphone. Even professional studio recordings &lt;em&gt;has&lt;/em&gt; noise, and it is present in &lt;em&gt;every single take&lt;/em&gt;. They are digitally suppressed in post production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise, a radar has to be tuned to &quot;see&quot; the specific type of reflections it is built for. In the case of civilian ATC radar, it is tuned to see large and slow moving objects, and filters out &quot;noise&quot; data which does not correspond to this profile. A fast moving military jet may be invisible to radar. A fast moving missile is more than likely invisible to controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Partly due to their inaccuracy, controllers seldom use primary radar to track planes. They use &quot;secondary radar&quot;, which in simple terms receives data like location, airspeed, heading and altitude broadcasted from the plane's transponder.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for the article you linked, it states wrongly that fighter jets cannot fly at 36,000 feet, as pointed out by NathanG. Even propeller planes can fly at 25,000 feet nowadays. I also agree that probably the aircraft has a week ADB-S transponder that is not received by ground stations.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-09-07T13:44:14.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8495" PostTypeId="1" AcceptedAnswerId="8496" CreationDate="2014-09-07T16:16:03.437" Score="18" ViewCount="15664" Body="&lt;p&gt;It's on most commercial aircraft and large aircraft with turbofan engines... Is there a specific name for it? Does it serve any other functions apart from attaching to the wing and feeding the engine the essentials? Has there been any aviation incidents that involved something malfunctioning or breaking inside of it? Or some other interesting things about it? Just out of curiosity! Thanks! :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cHhWv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3023" LastEditorUserId="3023" LastEditDate="2014-09-07T16:23:15.393" LastActivityDate="2017-01-12T17:03:16.690" Title="What's that component between the engine and wing?" Tags="&lt;jet-engine&gt;&lt;aircraft-systems&gt;&lt;fixed-wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8496" PostTypeId="2" ParentId="8495" CreationDate="2014-09-07T16:21:41.897" Score="21" Body="&lt;p&gt;It's a hard-point called an &quot;engine pylon&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3e/DC-10_engine-pylon.svg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, some designs use specific points designed to fail if there is excessive force, allowing the engine to separate from the aircraft without ripping the entire wing apart which would obviously be a catastrophic event. It has happened on a few occasions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above image is from the Wikipedia page on the &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_191&quot; rel=&quot;nofollow noreferrer&quot;&gt;American Airlines 191 accident&lt;/a&gt;, where, due to a faulty maintenance practice of using forklifts for removing and reattaching the engine/pylon assembly, the aft bolts were damaged. The pylon eventually failed, allowing the engine and pylon to push up and over, separating from the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other examples include &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_358&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines 258&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al_Flight_1862&quot; rel=&quot;nofollow noreferrer&quot;&gt;El Al 1862&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.200" LastActivityDate="2014-09-19T15:42:40.840" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8497" PostTypeId="2" ParentId="8495" CreationDate="2014-09-07T16:24:04.183" Score="8" Body="&lt;p&gt;It's a pylon and indeed just hold up the engine and connects it to the craft. They are designed so that excessive force will cleanly separate the engine without damaging the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_191&quot; rel=&quot;nofollow&quot;&gt;American airlines flight 191&lt;/a&gt; had the pylon fail in midair due to mishandling of the engine during maintenance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 engines separated in &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al_Flight_1862&quot; rel=&quot;nofollow&quot;&gt;El Al flight 1862&lt;/a&gt;; in this case the inboard engine separated cleanly but then slammed into the outboard engine where it did damage the wing. The same thing happened a year earlier in &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_358&quot; rel=&quot;nofollow&quot;&gt;China Airlines flight 358&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="2884" LastEditDate="2014-09-08T09:40:31.563" LastActivityDate="2014-09-08T09:40:31.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8499" PostTypeId="1" CreationDate="2014-09-07T22:45:12.320" Score="2" ViewCount="689" Body="&lt;p&gt;I have an FAA A320 initial pilot-in-command (PIC) type rating but haven't flown the actual aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently I am undergoing the second-in-command (SIC) type rating. I have completed the ground school program, Fixed Base Simulator and the Full Flight Simulator exactly like the Practical Test Standards for PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do I now according to FAA need to do a check ride? Or should I be issued the SIC privileges?&lt;/p&gt;&#xA;" OwnerUserId="3454" LastEditorUserId="19" LastEditDate="2016-07-28T15:45:48.563" LastActivityDate="2016-07-28T15:45:48.563" Title="Do I need a checkride for an initial SIC A320 type rating?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;airliner&gt;&lt;checkride&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8500" PostTypeId="2" ParentId="8484" CreationDate="2014-09-07T23:42:12.957" Score="9" Body="&lt;p&gt;As you've mentioned, your tolerance will build up over time so a simple, partial answer is to &lt;strong&gt;be patient and fly in small doses&lt;/strong&gt;. Two 20 minute flights with a break between is much much better than a single hour long flight.  You'll learn more, stay focused, and acclimate faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Try not to move your head much during maneuvers&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a loop, I typically look at my left wing tip until I'm about 3/8's through the loop, then I transition to looking &quot;up&quot; to catch the horizon as I approach the top of the loop. Any more movement than that might be a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bill Thomas's classic book &lt;a href=&quot;http://amzn.com/B009T5N08G&quot;&gt;Fly For Fun&lt;/a&gt; describes where to look for many of the basic maneuvers.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2014-09-07T23:42:12.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8501" PostTypeId="2" ParentId="8484" CreationDate="2014-09-08T03:04:12.830" Score="9" Body="&lt;p&gt;I used to feel strong motion sickness when flying aerobatics. I got to the point I could burn off the acro tanks in an Extra 300 without getting sick. I did 3 things:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Repeatedly spinning in an office chair until I felt dizzy then getting up and walking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Flying as much as I could, and when I did, I would fly until I felt sick, then fly straight and level until I felt a bit better, then would do an avalanche maneuver (snap-roll at the top of a loop), then would fly straight and level again... and do it again, gradually pushing myself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) If you're in a car and not driving, try reading until you start feeling sick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Somehow I never threw up flying aerobatics, but I did come really close a number of times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried to relax, control my breathing, bring a little water with me, and always push myself a bit. And somehow that worked for me. Also if you do some aggressive maneuvers like lomcováks, long tail slides, push humpty-bumps, and accelerated spins, most other maneuvers will seem much more tame and you'll be able to relax and enjoy them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck and have fun!&lt;/p&gt;&#xA;" OwnerUserId="3457" LastEditorUserId="3457" LastEditDate="2014-09-16T20:39:53.187" LastActivityDate="2014-09-16T20:39:53.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8502" PostTypeId="1" AcceptedAnswerId="8505" CreationDate="2014-09-08T08:39:55.633" Score="10" ViewCount="1335" Body="&lt;p&gt;When parachute jumps are performed from 32000 feet (or between 28000 - 30000 feet), once the jumpers are let out from the aft (cargo area), does the aircraft need to change altitude (e.g. descent)? Can the crew not pressurise the aircraft by simply closing the door?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, I am talking about wide body aircraft with cargo deployment facility.&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="6" LastEditDate="2014-09-08T19:21:15.913" LastActivityDate="2014-09-08T19:33:31.060" Title="Can an aircraft re-pressurize at high altitude?" Tags="&lt;cabin-pressure&gt;&lt;parachute&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8503" PostTypeId="2" ParentId="8502" CreationDate="2014-09-08T10:43:00.710" Score="9" Body="&lt;p&gt;The only available source I found through searching the web is from a &lt;a href=&quot;http://forums.watchuseek.com/f7/pressurization-cargo-transport-aircraft-others-122300.html&quot;&gt;military watches forum&lt;/a&gt;, where a similar question has been asked and answered. The forum thread also references parachute jumping from high altitude, referred to as &lt;a href=&quot;http://en.wikipedia.org/wiki/High-altitude_military_parachuting&quot;&gt;High-Altitude-Low-Opening (HALO)&lt;/a&gt; jumping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressurization of an aircraft is accomplished through using &lt;em&gt;bleed air from the compressor stages of the engines&lt;/em&gt;. The bleed air is then run through &lt;em&gt;heat exchangers to&lt;/em&gt; match the temperature of the cabin and through  &lt;em&gt;valves/regulators&lt;/em&gt; to achieve the desired pressurization of the cabin. &lt;strong&gt;Essentially this means that the aircraft can re-pressurize without a descent, by closing all doors and using the bleed air for pressurization&lt;/strong&gt;. Since air density at high altitudes is very low, oxygen needs to be supplied from on-board tanks during the drop to counter &lt;a href=&quot;http://en.wikipedia.org/wiki/Hypoxia&quot;&gt;hypoxia&lt;/a&gt;, which is why the crew needs to don their oxygen masks.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2014-09-08T19:33:31.060" LastActivityDate="2014-09-08T19:33:31.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8504" PostTypeId="2" ParentId="2198" CreationDate="2014-09-08T10:54:39.257" Score="19" Body="&lt;p&gt;The following is, in respect of aircraft, speculation. However, I did spend a decade working on the GPS based tracking systems mentioned in the question, with particular emphasis on remote operations in rural Australia. We did trial the use of Iridium, so I will comment on that too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly such systems do &lt;em&gt;not&lt;/em&gt; report in real time, that is baloney put out by marketroids who don't even know what real-time means (I discovered this while trying to persuade them not to put unsupportable claims in promotional material.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vehicle positioning and telemetry systems report periodically. The more sophisticated units are store and forward, which means they log position at frequent intervals and upload bursts of telemetry as and when the network is available. The &quot;real-time&quot; ones use the telephone network, while others upload as they pass through WIFI waypoints, usually at depots and pickup locations. Hybrids exist, reporting sparse data periodically through the network and uploading higher resolution sampling at waypoints. The more sophisticated units have rules for priority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Land freight in the United States runs along narrow concentrated corridors (roads and rails) that are well serviced by the telephone network. This is also true for freight on the eastern seaboard of Australia, but availability diminishes as you head west. As a result, the network is available most of the time so the units can upload at regular intervals, maintaining the illusion of real time tracking. Some systems also support manual polling of unit to obtain fresher position information on demand but this only works when the unit happens to be on the network.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we tried it, Iridium had dismal bandwidth at outrageous cost. In the southern hemisphere, the satellite density is so low that you might see a satellite briefly every twenty minutes or so. The time between deciding things are out of control and the aircraft crashing could easily see the plane down before a satellite connection is available, although I suppose things might be better at high altitude with much wider horizons. The Iridium systems I had were power greedy, but that's not a problem in vehicle mounted systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft move too fast for the cellphone network; by the time they finish negotiating with one cell they're over the next. Also their altitude means they get similar signal strength from several neighbouring cells making them hop between cells unpredictably. I have been in a private plane in which the radio equipment failed, and the pilot had a devil of a time keeping a cellphone connection to the tower due to speed and altitude. Commercial craft are higher and faster so I doubt it would work at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Out at sea, there's just nothing but satellite comms. Over the Atlantic I imagine it wouldn't be too bad, but there are a lot of commercial routes that go a long way in the middle of big wet nowhere. Also there are a &lt;em&gt;lot&lt;/em&gt; of commercial flights, and they move so fast you'd have to report every second to get any kind of positional precision. I'm not sure the civilian satellite network could cope. I know they stream vast amounts of TV data, but (a) that bandwidth is committed, and (b) that's loss tolerant streaming. It's high lag. When you try to use them to support non-loss network chatter the throughput plummets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea why the black box isn't ejected prior to impact. You could easily set up a system that once armed would eject it when the craft dropped below a certain altitude. If it were me there'd be a little parachute and a self-inflating weather balloon, and the plane would be transmitting position updates to the ejected system until it failed. A little solar charger could keep the transponder going and with the balloon keeping the unit up off the water it shouldn't be hard to find. Such a system would have no network dependencies and although it might well drift a long way before being collected, it would know where it was at the time of ejection and &lt;em&gt;exactly&lt;/em&gt; where the aircraft was when it ceased transmitting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An interesting question from the comments:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Perhaps the aircraft could maintain an adaptive network between them&#xA;  as they fly around? That would increase the range of the coverage. The&#xA;  bandwidth for reasonably periodic position packets is low enough that&#xA;  one aircraft could easily forward packets from dozens of others, (and&#xA;  then on to base stations).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's a nice idea but oceans are colossal. Even with hundreds of flights in the air at the same time, even in air corridors over land, being in visual range is a periodic event. Only in the crowded airspace around a commercial airport is this likely to work - and when you're that close you have comms anyway. A shame because it's creative and technically interesting.&lt;/p&gt;&#xA;" OwnerUserId="3439" LastEditorUserId="3439" LastEditDate="2016-05-25T23:37:15.243" LastActivityDate="2016-05-25T23:37:15.243" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8505" PostTypeId="2" ParentId="8502" CreationDate="2014-09-08T15:06:09.273" Score="15" Body="&lt;p&gt;Pressurization is controlled by two processes: air in and air out.  Air is constantly being let out of the cabin through (at least) 2 outflow valves, typically located at the aft limit of the pressure vessel.  Air is let into the cabin through the air cycle machines (a.k.a the &quot;packs&quot;) which are provided with very hot and high pressure air from the compressor stage of the engines and eventually output into the cabin through the air conditioning vents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During normal cruise flight, the mass flow rate of air into the cabin is constant (because the flow rate through the engine compressor is constant), thus pressurization is maintained by actuating the outflow valves.  Open them up a little more to raise the cabin altitude, close them up a little more to descend the cabin altitude.  Note that while maintaining a constant cabin altitude the outflow vales are partially open -- the incoming air is more than adequate to pressurize the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a main cabin door or something bigger is opened, the airplane will no longer maintain pressurization and everyone must don oxygen masks to avoid unconsciousness.  With a planned cabin dump, masks will be donned before the cabin is evacuated, which will happen before any doors are opened.  As noted by others, the pilot oxygen is fed from cylinders of pure oxygen and will last a long time.  Passenger emergency oxygen is from chemical oxygen generators and lasts 12-15 minutes.  I'm not sure what type of oxygen masks the HALO jumpers would wear, but presumably they have portable oxygen for the jump not related to the airplane oxygen facilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When all of the jumpers are away the doors are closed and once again the airplane is capable of pressurization.  The outflow valves will be commanded closed and the cabin altitude will start descending.  Once the cabin altitude is back down to normal levels, the crew will remove and stow their oxygen masks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no need to descend to accomplish this because the air provided by the engines is much higher pressure than even sea level air.  Re-pressurization is accomplished by closing up the airplane and letting air accumulate in the cabin, thus raising the pressure.  Once the target pressure is realized (~8000 ft), then the outflow valves partially open to stop descending the cabin and to maintain the target pressure.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-09-08T15:06:09.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8507" PostTypeId="2" ParentId="8486" CreationDate="2014-09-08T16:04:10.813" Score="8" Body="&lt;p&gt;Unruly passengers can face the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Monetary fines&lt;/li&gt;&#xA;&lt;li&gt;Prison sentences&lt;/li&gt;&#xA;&lt;li&gt;A ban from that airline&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Unruly_aircraft_passenger#Consequences&quot; rel=&quot;nofollow noreferrer&quot;&gt;Excerpt from Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the United States, passengers who disrupt the duties of a flight&#xA;  crew member can face fines up to $25,000 and sometimes lengthy prison&#xA;  sentences.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;IATA has a policy for these passengers mentioned &lt;a href=&quot;http://www.iata.org/publications/ceo-brief/apr-2014/Pages/unruly-passengers.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, and more information is &lt;a href=&quot;http://www.iata.org/policy/Pages/tokyo-convention.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO has a &lt;a href=&quot;http://www.iata.org/policy/Documents/2013-V1-PUBLIC-Guidance-on-Unruly-Passenger-Prevention-and-Management.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;detailed document&lt;/a&gt; on unruly passenger prevention and management. They have adopted a &lt;a href=&quot;http://www.mondaq.com/unitedstates/x/311196/Aviation/Unruly+Passengers+Beware+ICAO+Delivers+Montreal+Protocol+2014+To+Enhance+Enforcement+Measures+Against+Unruly+Passengers&quot; rel=&quot;nofollow noreferrer&quot;&gt;new protocol&lt;/a&gt; to amend the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tokyo_Convention&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tokyo Convention&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="22726" LastEditDate="2019-02-16T22:39:15.047" LastActivityDate="2019-02-16T22:39:15.047" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="8508" PostTypeId="2" ParentId="8499" CreationDate="2014-09-08T16:06:31.513" Score="2" Body="&lt;p&gt;A PIC type supercedes and SIC type.  An SIC type is really just a formalism of 121 initial first officer training to satisfy specific ICAO requirements.  A typical route to an SIC type is airline ground school, FFS and then company checkride (no APD, no DE, just a check airman) and the issuance of the SIC type.  If you already had a PIC type you'd go through the same training and company check (required by company approved training), but you wouldn't get an SIC type as you already have a PIC type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA shouldn't require anything out of you if you are PIC typed already.  The company may require you to do the full FO training and the FO company checkride as part of its own FAA approved requirements.  If you want a more specific answer, you could provide more details about how your training is being conducted or you could ask your facilities training department or director of training.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-09-08T16:06:31.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8509" PostTypeId="2" ParentId="8479" CreationDate="2014-09-08T17:14:13.997" Score="2" Body="&lt;p&gt;This is as much a photography question as an aviation one. The type of aircraft you might want depends on the type of picture you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a picture from low altitude, showing the area nearby, a helicopter or a quadcopter (depending on local regulations) would be ideal. This would let you hover in one spot, and rotate to cover the full panorama. The movement of the aircraft could easily be compensated for in processing the photos. A quadcopter holding a position by GPS should be very stable for long enough to take the photos.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your picture is at a higher altitude, focusing more on things further away, a small plane could work. Many general aviation aircraft can fly fairly slow. With only more distant objects as the subject, a plane in a turn at under 100 knots should be slow enough that the perspective change would be negligible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you could get something like a simplified version of Google's street view setup, and send it up on a quadcopter, that would probably give the absolute best result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this more general question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3814/what-is-a-good-plane-for-aerial-photography&quot;&gt;What is a good plane for aerial photography?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-09-08T17:14:13.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8510" PostTypeId="2" ParentId="8495" CreationDate="2014-09-08T17:32:54.653" Score="6" Body="&lt;p&gt;This part is called the &quot;pylon&quot; or &quot;strut&quot; for the engine. It holds the engine on the wing, provides a path for all of the engine systems to connect, and includes the aerodynamic fairing to cover it all. The strut is designed to prevent a &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2010_q4/3/&quot; rel=&quot;nofollow noreferrer&quot;&gt;fire in the engine area&lt;/a&gt; from spreading to the wing. Mounting the engine below and forward of the wing leading edge provides &lt;a href=&quot;https://aviation.stackexchange.com/q/12109/1696&quot;&gt;some advantages&lt;/a&gt; over &lt;a href=&quot;https://aviation.stackexchange.com/q/1397/1696&quot;&gt;other options&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the strut is installed on the wing, it is intended to be permanently attached there. As shown in &lt;a href=&quot;https://aviation.stackexchange.com/a/8496/1696&quot;&gt;falstro's picture&lt;/a&gt;, the engine mounts are installed on the engine, and allow engines to be installed and removed as needed. When no engines are installed, a weight is &lt;a href=&quot;http://www.wired.com/images_blogs/autopia/2010/02/dsc_0424-660x441.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;suspended from the strut&lt;/a&gt; to balance the aircraft and prevent the plane from &lt;a href=&quot;http://www.youtube.com/watch?v=cHhZwvdRR5c&quot; rel=&quot;nofollow noreferrer&quot;&gt;tipping backwards&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are differences in design between manufacturers. Boeing struts are designed to break away from the wing under extreme loads. The strut attaches to the wing using fuse pins, which will fail at a specific loading, lower than the strength of the wing. This prevents the wing from breaking under the load, which could cause the fuel tanks to break open and start a fire. Examples of engines breaking away as designed are the &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow noreferrer&quot;&gt;Asiana 214&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Lion_Air_Flight_904&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lion Air 904&lt;/a&gt; incidents last year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus struts are designed to &lt;a href=&quot;http://community.seattletimes.nwsource.com/archive/?date=19930109&amp;amp;slug=1679083&quot; rel=&quot;nofollow noreferrer&quot;&gt;remain attached to the wing&lt;/a&gt;. This actually allows the structure to be less complex, and Airbus struts tend to be noticeably more narrow than comparable Boeing struts. Other methods are used to maintain safety in a crash, such as keeping the area directly above the engine as a &quot;dry bay&quot;, which is not used to store fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an &lt;a href=&quot;http://www.freepatentsonline.com/y2009/0294579.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus patent&lt;/a&gt; for a strut design using composite panels, which describes the strut.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned by falstro, there are multiple incidents where the structure in the pylon has failed, resulting in the engine coming off of the plane in flight. There have been both design and maintenance causes for such incidents, and both design and maintenance changes have been made to address those issues.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-08-06T16:16:58.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8511" PostTypeId="2" ParentId="8409" CreationDate="2014-09-08T19:43:50.307" Score="8" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/news/safety_briefing/2002/media/julyAug2002.pdf&quot; rel=&quot;noreferrer&quot;&gt;July/August 2002 edition&lt;/a&gt; of FAAviation News (now &lt;a href=&quot;http://www.faa.gov/news/safety_briefing/&quot; rel=&quot;noreferrer&quot;&gt;FAA Safety Briefing&lt;/a&gt;) has a detailed article on owner-produced parts, including advice on best practices if you want to make your own parts. It does confirm that owners have very broad authority to do so, provided that they document everything properly.&lt;/p&gt;&#xA;&lt;p&gt;Typical reasons for producing your own parts are (I've paraphrased them from the article here):&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft has been out of production for years&lt;/li&gt;&#xA;&lt;li&gt;The aircraft is an orphan without a Type Certificate&lt;/li&gt;&#xA;&lt;li&gt;There is no technical support because the aircraft is so old&lt;/li&gt;&#xA;&lt;li&gt;There may be long delays in getting parts from the manufacturer&lt;/li&gt;&#xA;&lt;li&gt;The price of official parts is extremely high&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;As for requirements of the part itself, the article list four characteristics that a part must have:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The part must be properly designed&lt;/li&gt;&#xA;&lt;li&gt;The part must be produced to conform to the design&lt;/li&gt;&#xA;&lt;li&gt;The part's production must be properly documented&lt;/li&gt;&#xA;&lt;li&gt;The part must be properly maintained&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The owner must be involved in the production but doesn't actually have to do the manufacturing himself:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The aircraft owner must participate in the manufacture of the part&#xA;in at least one of five ways for it to be considered an Owner Produced&#xA;Part.&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The owner provides the manufacturer of the part with the design or performance data.&lt;/li&gt;&#xA;&lt;li&gt;The owner provides the manufacturer of the part with the materials.&lt;/li&gt;&#xA;&lt;li&gt;The owner provides the manufacturer with fabrication processes or assembly methods.&lt;/li&gt;&#xA;&lt;li&gt;The owner provides the manufacturer of the part with quality control procedures.&lt;/li&gt;&#xA;&lt;li&gt;The owner personally supervises the manufacture of the new part.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;More recently, in the September 2014 edition of the &lt;a href=&quot;http://www.cessna.org/&quot; rel=&quot;noreferrer&quot;&gt;Cessna Pilots Association&lt;/a&gt; magazine, &lt;a href=&quot;http://www.savvyaviator.com/&quot; rel=&quot;noreferrer&quot;&gt;Mike Busch&lt;/a&gt; has an article on replacement parts that calls the current regulations on owner produced parts &amp;quot;extremely liberal&amp;quot;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;“Owner-produced parts” do not require a  PMA. These are parts produced&#xA;by an aircraft  owner for use on his own aircraft, and not  offered&#xA;for sale. There is an FAA letter of  interpretation that sets forth&#xA;precisely what  an owner's involvement must be to qualify a  part as&#xA;“owner-produced,” and it is extremely  liberal. The owner need not&#xA;actually  manufacture the part himself, so long as  he provides&#xA;specifications or materials  or supervision or some other meaningful&#xA;participation in the part's production.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Unfortunately, he didn't mention exactly which letter of interpretation covers these parts but the FAA magazine article refers to an &amp;quot;FAA Memorandum dated&#xA;August 5, 1993&amp;quot; and I guess it's probably the same one. I wasn't able to find it on the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/Interpretations/&quot; rel=&quot;noreferrer&quot;&gt;FAA site&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-08T19:43:50.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8512" PostTypeId="1" AcceptedAnswerId="8513" CreationDate="2014-09-08T22:26:21.677" Score="4" ViewCount="3012" Body="&lt;p&gt;About 57 months ago I got my first FAA medical, a second class certificate.  I am currently a sophomore in college.  I'm in AFROTC trying to become an Air Force pilot so I wanted to get a first class medical just to make sure that I can (I realize military aviation medicals are even more intense though).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What types of things do they do during an exam for a first class medical that aren't included in the exam for a second class?  Also, if I &quot;fail&quot; one of the tests while being examined for a first class - can I still get a second or third class medical to keep my private pilot privileges?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="487" LastEditDate="2015-03-24T20:52:35.017" LastActivityDate="2015-03-24T20:52:35.017" Title="What should I expect during a first class medical examination?" Tags="&lt;usa&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8513" PostTypeId="2" ParentId="8512" CreationDate="2014-09-08T22:41:10.970" Score="6" Body="&lt;p&gt;You can see the requirements for all FAA medicals in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3aea3f4040a26d213f7d732ca3b8f321&amp;amp;node=pt14.2.67&amp;amp;rgn=div5&quot;&gt;14 CFR 67&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, S&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3aea3f4040a26d213f7d732ca3b8f321&amp;amp;node=pt14.2.67&amp;amp;rgn=div5#sp14.2.67.c&quot;&gt;ubpart C (67.2xx)&lt;/a&gt; deals with second class medicals and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3aea3f4040a26d213f7d732ca3b8f321&amp;amp;node=pt14.2.67&amp;amp;rgn=div5#sp14.2.67.b&quot;&gt;Subpart B (67.1xx)&lt;/a&gt; deals with first class medicals.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only difference my cursory read of these regulations revealed is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;x.111 - Cardiovascular. A first class medical requires EKG after your 35th birthday and every year after age 40.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This leads me to believe any real differences are likely in the ME's guidelines for issuing the medical, and I am not familiar with those.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only other differences relate to duration and requirement for the exercise of privileges. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On your second question, if you apply for a first class medical and for some reason could not qualify for one, you will be denied or deferred even if you could hold a lower class medical (this is also true of a second class application).  The only possibilities at the end of a medical exam are walking out with a medical of the class you applied for or walking out without a medical.  There is no fallthrough to a lower class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an issue that you believe would inhibit your ability to get a first class medical, an avenue to explore this is through &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical&quot;&gt;AOPA&lt;/a&gt; where you can talk with a doctor and get advice on your ability to pass a medical and support in handling a deferred medical application.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-09-08T22:41:10.970" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8514" PostTypeId="5" CreationDate="2014-09-09T09:30:22.430" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-09-09T09:30:22.430" LastActivityDate="2014-09-09T09:30:22.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8515" PostTypeId="4" CreationDate="2014-09-09T09:30:22.430" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-09-09T09:30:22.430" LastActivityDate="2014-09-09T09:30:22.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8516" PostTypeId="1" AcceptedAnswerId="8520" CreationDate="2014-09-09T12:49:32.023" Score="19" ViewCount="9799" Body="&lt;p&gt;I understand the delta wing was chosen because of the supersonic cruise (like the Concorde), and canards were added to reduce the approach/landing speed. But canards may be used without delta wing (e.g. Focke Wulf F-19, Soukhoï Su-47, Rutan Voyager,...), so I don't understand why the canard wing configuration is not used among commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/72ax0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/72ax0.jpg&quot; alt=&quot;TU144&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1467" LastEditDate="2018-02-22T06:14:43.800" LastActivityDate="2018-11-01T02:19:05.110" Title="Why is the Tu-144 the only commercial airplane with canard configuration?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;control-surfaces&gt;&lt;canard&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8517" PostTypeId="2" ParentId="8516" CreationDate="2014-09-09T13:22:30.897" Score="13" Body="&lt;p&gt;Because it is not aerodynamically efficient. To achieve stability the forward surface has to fly at higher angle of attack than the rear. So the canard has to fly at rather high angle of attack which leads to high drag and disrupts airflow for the main wing further reducing it's efficiency. It is not a chance that most modern jets have the same layout. It is most efficient known design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also while the higher angle of attack of the canard leads to it's biggest advantage, the gentle stall behaviour where the aircraft just gently lowers nose it means that the maximum usable angle of attack is reduced. This increases landing speed and reduces the safety margin should the aircraft get caught in a wind-shear. Suitable wing twist provides not much worse stall behaviour without these disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With delta wings, the canard has advantage that it increases stall angle of attack and thus maximum lift, because the canard acts as vortex generator. This means sharper turns at high speed and lower landing speed, which is why this configuration is popular in fighters (Eurofighter Typhoon, Dassault Rafale, Saab JAS-39 Grippen) where manoeuvrability is more important than efficiency. Besides these designs are not stable (stabilized by computer instead; allows faster control response), so the canard does not produce that much drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Sukhoi Su-47 uses canard primarily for layout reasons as the forward-swept wing does not leave much room at the tail, but a lot of room at the nose. And it's not clear how good the layout actually is; it does not seem to be followed by other military designs. Grumman X-29 first flew in 1984, but no follow up design was created.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Rutan Voyager counters the inefficiency by not flying the canard at high angle of attack, which yields good efficiency, but poor pitch stability. It was manageable for good test pilots, but not suitable for average airline pilot. And note that this also eliminates the stall behaviour advantage of canard.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-09-09T21:23:20.217" LastActivityDate="2014-09-09T21:23:20.217" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8519" PostTypeId="2" ParentId="8516" CreationDate="2014-09-09T13:23:17.783" Score="16" Body="&lt;p&gt;The canards on the Tu-144 weren't canards technically. They were static surfaces, not moving.&lt;br/&gt;&#xA;They were purely lift devices to improve low speed handling (and thus help reduce landing speed which was excessively high).&lt;br/&gt;&#xA;These were added because low speed handling was found to be deficient, due to the inferior (as compared to Concorde) wing design.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-09-09T13:23:17.783" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8520" PostTypeId="2" ParentId="8516" CreationDate="2014-09-09T15:12:30.090" Score="28" Body="&lt;p&gt;Short answer: Canards make most sense with negative static stability and high maneuverability. Commercial aircraft don't need either, so a conventional layout works best.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a statically stable aircraft, the conventional layout gives most efficiency with sufficient damping. Static stability requires that the forward lifting surfaces create more lift proportionally to their size than the rear surfaces. &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529#7529&quot;&gt;Here is an answer&lt;/a&gt; to a related question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You want the airplane to return to the original flight attitude if it has been disturbed, say by a gust or a jolt on the stick. This can be done by creating proportionally more lift with the forward surfaces (= the wing in a conventional configuration) than with the rear surfaces (= the wing in a canard configuration). Say the jolt pitches the aircraft up. Now the aerodynamic forces should change in a way which increases lift proportionally more on the rear surfaces, so the aircraft pitches down and returns to it's original attitude. By distributing lift the way I mentioned above, the same change in angle of attack on both forward and rear surface will create a proportionally higher lift increase on the rear surface, making the aircraft (statically) stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That requires that one of the (mostly) two surfaces is not contributing as much to lift creation than it could. You want this surface to be the smaller one of both, so the whole configuration can create as much lift as possible at a given speed. A canard would be a poor choice for a commercial airplane, because the big wing would now fly at a fraction of it's potential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on/8061#8061&quot;&gt;Once you shift the center of gravity back&lt;/a&gt; to improve maneuverability, things get different: Now the rear surface is creating proportionally more lift, so the smaller surface should go in front. Voilá, a canard!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now add forward sweep, which will make the wing tips twist to higher angles of attack when lift is increased, and you get a really responsive aircraft (but need to be careful not to overstress it!). This was done on the X-29 and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-47&quot; rel=&quot;nofollow noreferrer&quot;&gt;Berkut&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As jwenting pointed out, the canard on the Tu-144 was not a control surface, but should be considered a detached &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading-edge_slats&quot; rel=&quot;nofollow noreferrer&quot;&gt;slat&lt;/a&gt; of sorts. Also, by adding some lift ahead of the wing it allows to lower the wing flaps in slow flight, increasing the lift potential of the main wing while maintaining the location of the center of gravity and stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And while we are at it: The &lt;a href=&quot;http://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piaggio Avanti&lt;/a&gt; has a canard, and a conventional tail, too. Here the canard helps to put the wing spar behind the cabin area, makes it easier to fly with a wide range of c.g. locations and to increase aerodynamic damping. This is one of very few examples in commercial aircraft of canards done right!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-11-01T02:19:05.110" LastActivityDate="2018-11-01T02:19:05.110" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="8521" PostTypeId="1" AcceptedAnswerId="8524" CreationDate="2014-09-09T15:52:55.817" Score="6" ViewCount="954" Body="&lt;p&gt;My question intends to find out how maps are downloaded/buffered at Ground Control Station's for &lt;a href=&quot;http://en.wikipedia.org/wiki/Unmanned_aerial_vehicle&quot; rel=&quot;nofollow&quot;&gt;UAV&lt;/a&gt; operations. I understand GPS transmitters relay the exact location of an aircraft on a map. However, the map needs to be loaded/buffered in real time as the UAV covers ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a UAV as large as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk&quot; rel=&quot;nofollow&quot;&gt;RQ-4 Global Hawk&lt;/a&gt;, with a range of 14000 kms, how is the map loaded in real time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, for amateur or small scale UAVs/&lt;a href=&quot;http://en.wikipedia.org/wiki/Micro_air_vehicle&quot; rel=&quot;nofollow&quot;&gt;MAVs&lt;/a&gt;, is the map updated in real time as the aircraft/rotorcraft covers more ground? Or is that the map is downloaded pre-flight, based on the range of the aircraft? This would be preferable in terrains with poor or no signal connectivity.&lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="189" LastEditDate="2015-04-18T15:30:03.127" LastActivityDate="2015-04-18T15:30:03.127" Title="How are maps loaded in UAVs?" Tags="&lt;navigation&gt;&lt;ground-operations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8522" PostTypeId="2" ParentId="8521" CreationDate="2014-09-09T16:23:53.300" Score="9" Body="&lt;p&gt;You seem to assume the maps are being transmitted &lt;em&gt;from&lt;/em&gt; the UAV.&lt;br&gt;&#xA;They are almost certainly not (and if they &lt;em&gt;are&lt;/em&gt; that's a poorly engineered system and I would be embarrassed that my government wasted my tax dollars on such a lousy design).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maps are relatively static data, so it would be logical to store them on the computers at the ground control station (where you could have the entire world's terrain and likely aeronautical charts/airspace boundaries on your hard drive, along with current weather data and other useful information).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving the map to keep up with the position being relayed from the UAV is computationally trivial: iPads do it for real aircraft (&lt;a href=&quot;http://foreflight.com&quot;&gt;ForeFlight&lt;/a&gt; &amp;amp; similar products) and your car's GPS system does it when you drive - neither system is as powerful as the typical desktop computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the UAV would relay to the ground station is its position (and any other pertinent data dictated by its mission, such as photos/video). This arrangement minimizes the bandwidth required to control the vehicle, as well as its RF signature (less stuff to transmit back to base).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For &lt;em&gt;autonomous&lt;/em&gt; UAVs, particularly ones which have to avoid airspace incursions, some subset of airspace data appropriate to the route of flight may be loaded on the vehicle, but I wouldn't call these &quot;maps&quot; - it's a much more compact representation of coordinates marking boundaries in 3D space (similar to the &lt;a href=&quot;http://ww1.jeppesen.com/industry-solutions/aviation/military/Flight-Management-System-NavData.jsp&quot;&gt;Jeppesen NavData products&lt;/a&gt; - possibly even using those products) . Such vehicles may also have terrain data loaded before flight if they lack other means to avoid collisions with terrain while operating autonomously.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Disclaimer:&lt;/strong&gt; I have no experience with the RQ4 or any other military UAVs - this is just a common-sense engineering assessment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-09-09T16:23:53.300" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="8523" PostTypeId="1" AcceptedAnswerId="8526" CreationDate="2014-09-09T17:16:41.257" Score="22" ViewCount="19869" Body="&lt;p&gt;If you have an airship filled with helium, how can you adjust your altitude?  i.e. how do you &quot;go up&quot; or &quot;go down&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even staying still would be a challenge: The way I see it, you'll never have exactly the same average density as air and therefore will always be either slightly falling or slightly rising.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the case that they have an extra tank of compressed gas as well as vents on the blimp and they make adjustmenst by increasing/decreasing internal pressure of the balloon?&lt;/p&gt;&#xA;" OwnerUserId="2847" LastEditorUserId="3386" LastEditDate="2016-06-23T10:46:26.873" LastActivityDate="2016-06-23T10:46:26.873" Title="How do blimps control altitude?" Tags="&lt;altitude&gt;&lt;airship&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8524" PostTypeId="2" ParentId="8521" CreationDate="2014-09-09T17:33:42.803" Score="5" Body="&lt;p&gt;For an application that were controlling a hobbyist UAV one could use something like the Google Maps API.  It provides services and data that will scale as the user scrolls in and out and as the UAV transitions to different areas.  It also has the advantage of having visual and road data as an option.  The downside is that unless you download enough data ahead of time you must have some sort of data connection to the application.  But, with the greater availability of the fast cell based data connections this is becoming less of an issue.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-09-09T19:15:42.780" LastActivityDate="2014-09-09T19:15:42.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8525" PostTypeId="2" ParentId="8523" CreationDate="2014-09-09T18:53:54.743" Score="4" Body="&lt;p&gt;Inside the airship are &lt;a href=&quot;http://en.wikipedia.org/wiki/Ballonet&quot; rel=&quot;nofollow&quot;&gt;ballonets&lt;/a&gt; that are filled with air. These can be easily inflated with compressor and deflated to outer atmosphere without wasting the precious lifting gas, especially in the new designs where the lifting gas is usually safe but expensive helium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In non-rigid and semi-rigid ships the ballonets are inside the gas cell. In rigid ships the ballonets were between the gas cells and were together with them constrained by the outer shell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are normally at least two ballonets, fore and aft, to provide pitch control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for altitude control, airships are actually stable in altitude. As the ship ascends, the shell does not allow the gas to expand as fast as the outer pressure declines, therefore reducing buoyancy. Of course as fuel is burnt, weight decreases and the pressure needs to be adjusted accordingly to maintain altitude.&#xA;Many airships also have swivelling engines allowing additional up or down thrust.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-09T18:53:54.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8526" PostTypeId="2" ParentId="8523" CreationDate="2014-09-09T18:57:08.353" Score="29" Body="&lt;p&gt;An airship pilot has three ways of adjusting lift:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Every lighter-than-air vehicle needs some ballast to adjust its weight. This could be sand, but mostly water is used.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A blimp is only partially filled with helium. The envelope is held taut by filling a bag inside with air, called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ballonet&quot; rel=&quot;noreferrer&quot;&gt;ballonet&lt;/a&gt;. If you press a little more air in this bag, the overall density of the gasses in the envelope goes up, while the volume stays practically constant. This allows for fine adjustment. Forward and aft ballonets even allow for trimming the pitch attitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When the airship moves, the air does provide a little dynamic lift or downforce, depending on pitch attitude and elevator deflection. This is a little tricky, because airships are not stable, and a pitch-up command will lead to altitude loss below a critical speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UuUy7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ballonets in this cutaway drawing of a Goodyear blimp are numbered 2 and 4. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a calm day, the biggest disturbance is actually the sun. If the envelope is exposed to direct sunlight, it will heat up and the gas within will be heated as well, causing the blimp to rise. If the sun is covered by a cloud, the gas cools down and loses some lift. On partially cloudy days it is not easy to keep the same altitude!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another threat is an unstable atmospheric temperature gradient. Glider pilots love this, because it will give them strong thermals, but the gas inside the airship will behave similarly to that bubble of warmer gas which causes thermals. When the airship rises, the gas inside cools less quickly than the surrounding air, and the airship will gain lift when it goes up. It becomes really bad on the way down: Now the gas warms up less quickly as well, and the airship loses lift as it comes down. The airship pilot needs to drop some ballast or create more dynamic lift, or his craft will slam into the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long-range airships like the LZ-127 used a mixture of hydrocarbon gases as fuel. This mixture (called &lt;a href=&quot;http://en.wikipedia.org/wiki/Blau_gas&quot; rel=&quot;noreferrer&quot;&gt;Blaugas&lt;/a&gt;) was balanced to be just as heavy as air and filled some of the gas cells within the envelope. Consumed fuel would be displaced by air, so no lift adjustment was needed on a long trip.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="946" LastEditDate="2014-09-10T19:00:23.913" LastActivityDate="2014-09-10T19:00:23.913" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8527" PostTypeId="2" ParentId="8521" CreationDate="2014-09-09T18:57:09.310" Score="4" Body="&lt;p&gt;Military UAV's have a library of maps (on a hard drive associated with the ground control station) that the pilot chooses from while flying.  Formal flying charts are loaded underneath a 'moving map' display.  The pilot can select a wide variety of charts from a small scale GNC to a large scale VFR chart.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a limit to the buffering obviously, and if the aircraft flies outside of the buffer than the pilot just manually loads a new map for the new area.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-09-09T18:57:09.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8528" PostTypeId="1" CreationDate="2014-09-09T21:24:34.513" Score="1" ViewCount="2041" Body="&lt;p&gt;What are the FAA Beacon Light Requirements for 80 foot tall High Mast Poles Near an Airport?  Specifically, do the RED beacon lights need to be illuminated 24 hours per day?  Or, do they only  need to be illuminated at night?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are examples of Holophane high mast pole installations around the country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/media/set/?set=a.236398096375560.78767.131284353553602&amp;amp;type=3&quot; rel=&quot;nofollow&quot;&gt;https://www.facebook.com/media/set/?set=a.236398096375560.78767.131284353553602&amp;amp;type=3&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/media/set/?set=a.194847107197326.56223.131284353553602&amp;amp;type=3&quot; rel=&quot;nofollow&quot;&gt;https://www.facebook.com/media/set/?set=a.194847107197326.56223.131284353553602&amp;amp;type=3&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3469" LastEditorUserId="62" LastEditDate="2014-09-09T21:58:29.290" LastActivityDate="2014-09-09T21:58:29.290" Title="Are red obstacle lights near an airport required to be lit during the day?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;visibility&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8529" PostTypeId="2" ParentId="8528" CreationDate="2014-09-09T21:57:02.537" Score="4" Body="&lt;p&gt;It's unclear exactly which lights you're referring to (none of the example pictures you linked to are red), but the &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/b993dcdfc37fcdc486257251005c4e21/$FILE/AC70_7460_1K.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA AC on obstruction lighting&lt;/a&gt; says that only structures over 200ft are required to be lighted:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Any temporary or permanent structure, including all  appurtenances,&#xA;  that exceeds an overall height of 200  feet (61m) above ground level&#xA;  (AGL) or exceeds any  obstruction standard contained in 14 CFR part&#xA;  77,  should normally be marked and/or lighted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, there are exceptions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA may also recommend marking and/or  lighting a structure that&#xA;  does not exceed 200 (61m)  feet AGL or 14 CFR part 77 standards&#xA;  because of its  particular location.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same document describes the use of red lights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Aviation Red Obstruction Lights&lt;/strong&gt;. Use flashing beacons and/or steady&#xA;  burning lights during  nighttime&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The rest of the document suggests that red lights are for night use and white for day use. The FAA also has a dedicated &lt;a href=&quot;https://oeaaa.faa.gov/oeaaa/external/portal.jsp&quot; rel=&quot;nofollow&quot;&gt;portal&lt;/a&gt; for obstruction evaluation and reporting if you're involved in building or managing potential obstacles.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-09-09T21:57:02.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8530" PostTypeId="1" AcceptedAnswerId="8531" CreationDate="2014-09-10T02:05:45.110" Score="17" ViewCount="3865" Body="&lt;p&gt;Per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1153&quot;&gt;14 CFR 61.153(c)&lt;/a&gt; candidates for an ATP license must &quot;be of good moral character&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does that actually mean and how does an examiner or the FAA verify it?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2018-06-22T09:18:51.240" Title="What does the FAA consider to be &quot;good moral character&quot;?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8531" PostTypeId="2" ParentId="8530" CreationDate="2014-09-10T04:59:06.717" Score="17" Body="&lt;p&gt;An examiner uses the contents of FAA Order 8900.1 - Flight Standards Information Management System (FSIMS)as guidance for doing their job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you might imagine, there is some guidance available for them &lt;a href=&quot;http://fsims.faa.gov/WDocs/8900.1/V05%20Airman%20Cert/Chapter%2003/05_003_001Rev1.htm&quot;&gt;there&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;VOLUME 5 (AIRMAN CERTIFICATION)&lt;/li&gt;&#xA;  &lt;li&gt;CHAPTER 2 (TITLE 14 CFR PART 61 CERTIFICATION OF PILOTS AND FLIGHT INSTRUCTORS)&lt;/li&gt;&#xA;  &lt;li&gt;Section 18 (Conduct an Airline Transport Pilot Certification, Including Additional Category/Class Rating)&lt;/li&gt;&#xA;  &lt;li&gt;Paragraph 5-704 (ELIGIBILITY –ATP CERTIFICATE – AIRPLANE, ROTORCRAFT, AND POWERED LIFT):&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;C. Good Moral Character Requirement:&lt;/strong&gt;&lt;br&gt;&#xA;  An applicant must be of good moral character. The inspector must ask an applicant if the&#xA;  applicant has been convicted of a felony. If the applicant’s answer is&#xA;  affirmative, the inspector should make further inquiry about the&#xA;  nature and disposition of the conviction. If an inspector has reason&#xA;  to believe an applicant does not qualify for an ATP certificate&#xA;  because of questionable moral character, the inspector must not&#xA;  conduct the practical test. Instead, the inspector will refer the&#xA;  matter to the immediate supervisor for resolution. The supervisor may&#xA;  need to consult with regional counsel for a determination concerning&#xA;  whether the applicant meets the moral character eligibility&#xA;  requirement.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's the basic guidance that the examiners have, but there are also legal cases that have delved into this area and give more specific examples.  I found a blog which covers it in some detail at &lt;a href=&quot;http://allaboutairplanes.wordpress.com/2011/07/14/good-moral-character-for-airline-transport-pilots/&quot;&gt;All About Airplanes&lt;/a&gt;.  Falsification of documents, embezzlement, and acting in a malicious manner towards others are cited as reasons that ATP certificates have been denied or revoked.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-09-10T04:59:06.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8532" PostTypeId="2" ParentId="3459" CreationDate="2014-09-10T08:56:43.263" Score="7" Body="&lt;p&gt;I fly the A320 and 321 which, at our company, had been equipped with nose cameras. The pictures, though, where just used for passenger entertainment during takeoff and landing and keep being disconnected by maintenance when failed due to high spare parts costs.&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2014-09-10T08:56:43.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8533" PostTypeId="2" ParentId="8521" CreationDate="2014-09-10T09:53:49.697" Score="1" Body="&lt;p&gt;Amatorial drones: normally these boards have flash memory as not-mandatory, everything has to be loaded in to RAM or on limited space on-board. Also communication between UAV and GCS is not mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most complete (open) GCS + software seems to be ArduPilot, and its trick is that the map is only PC-based; you set your travel point (waypoint) on GCS, connect the UAV by cable if no wireless link is present, upload the waypoint GPS coordinates, and let the mission begin.&#xA;If you have a wireless link you can obviously load or edit waypoint on-the-fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now think about this: how a map should be helpful to a drone? Because he may recalculate the route on its own.&#xA;But why should it do so?&#xA;Drones normally are &quot;blind&quot; to environment, and radar/lidar/vision items are complex, expensive or require a lot of computing power and space on the drone.&#xA;In that case adding a microSD with the map in full precision of the region you are gonna fly is not a problem (OpenStreetMap planet map is about 40GB), but again I assume the pathing algorithm would just override the waypoint setting every time a course correction is needed, and another specialized algorithm would kick in to avoid low-term collision, which ignores completely the route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that many drones have a &quot;return to home&quot; function, that when the link is lost and mission complete, the drone heads directly to home. And as many amatorial drones are blind, that may have unexpected results.&lt;/p&gt;&#xA;" OwnerUserId="3475" LastEditorUserId="97" LastEditDate="2014-09-11T01:36:34.527" LastActivityDate="2014-09-11T01:36:34.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8535" PostTypeId="1" CreationDate="2014-09-10T19:06:08.323" Score="11" ViewCount="5080" Body="&lt;p&gt;An aircraft that uses Turbofan or Turboprop engines would be taking the compressed air from 3rd stage and 6th stage (varies) and supplying it to the Pressurisation and Air Conditioning Kit (PACK). This air is cooled, filtered, and then supplied to the Fdeck, FWD and AFT cargo zones for temperature control and breathing. If my understanding is correct, PACK is a kind of compressor itself which cools the bleed air for circulation purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the engine has got LP and HP stages (i.e compressors), why can't the engine send the LP stage air into PACK just for filtering? Because LP air is surely cool air which I understand still requires filtering. Without knowing further , it surely saves a lot of effort for installing more compressors and therefore, creating a more complex pneumatic system. Has this not been done or is there something I am missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;KR,&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="19" LastEditDate="2017-05-05T09:09:59.440" LastActivityDate="2017-05-05T09:09:59.440" Title="Why is the compressed air (from engine compressors) taken from High Pressure (HP) stage instead of Low Pressure (LP) stage?" Tags="&lt;jet-engine&gt;&lt;cabin-pressure&gt;&lt;turboprop&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8536" PostTypeId="2" ParentId="8535" CreationDate="2014-09-10T19:18:56.190" Score="13" Body="&lt;p&gt;Coming from the compressor section of the engine, the bleed air is sent to the precooler. Even air from the &quot;low&quot; pressure section needs to be cooled before it is sent to the air conditioning system. Here is a precooler from a CitationJet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/enzWf.jpg&quot; alt=&quot;CitationJet Precooler&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://support.cessna.com/docs/custsupt/directapproach/Archives/aug05.html&quot; rel=&quot;noreferrer&quot;&gt;page with that image&lt;/a&gt; notes that the bleed air is &quot;hot enough to melt insulation and alter the heat treatment on aluminum alloys.&quot; The precooler reduces the temperature of this air and regulates the pressure to the pack system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the engine is at low power settings, bleed air is taken from the high pressure section. The engine must run fast enough that this provides enough pressure for the bleed system to operate properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the engine gets to a higher power setting, the bleed air is taken from the low pressure section. At higher engine speeds, this air still has the pressure required to run the bleed system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the bleed system needs a minimum pressure to operate, compressing the ambient air to this pressure will always add a certain amount of heat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a diagram of the bleed system, to help visualize what is going on. Note that even after the air goes through the precooler, it is still hot enough to be used for wing anti-ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9jYMW.png&quot; alt=&quot;Bleed system diagram&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-10T19:18:56.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8537" PostTypeId="2" ParentId="8535" CreationDate="2014-09-10T19:42:56.850" Score="12" Body="&lt;p&gt;Several principles come together here:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The pressurized air does its job similarly to the gases inside your fridge. Compressing a gas heats it up, and expanding it cools it down again. &lt;/li&gt;&#xA;&lt;li&gt;A heat exchanger can be proportionally smaller if the heat difference between the two media which exchange heat is bigger.&lt;/li&gt;&#xA;&lt;li&gt;Engines are designed for some air to be bled off.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If you cool the compressed gas, it will become very cool once it expands. If you take air from the HP stages, it will be hotter and need a smaller radiator to remove the same amount of heat compared to less compressed air from the LP stages.  The same holds true when this air is expanded and used for cooling. You can carry away a lot of heat energy by using this very cold, expanded air and can keep the heat exchanger small and light. Again, using less cold air would require a proportionally bigger heat exchanger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For every compressor stage there is an optimum mass flow at a given rotation speed where it works best. Depending on the operating conditions, performance will be improved if some air is bled off. I know, this is a very general statement, but I just want to get the point across that bleeding off some air is not always hurting performance.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-10T19:42:56.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8538" PostTypeId="2" ParentId="2745" CreationDate="2014-09-10T21:55:45.140" Score="11" Body="&lt;p&gt;Long story short, as best I can tell everywhere except Kazakhstan uses the ICAO SNOWTAM format. Kazakhstan uses two different Russian formats depending on what airport you're at, which is an interesting approach to say the least.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the Russian format is described &lt;a href=&quot;http://pilotnotes.wikispaces.com/Russia+and+the+CIS#OPERATIONS-Russian%20Friction%20Coefficient%20(FC)&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, it's a decimal value where less than 0.31 is &quot;unreliable&quot; and more than 0.41 is &quot;good&quot;. In fact, there are two Russian values: the &quot;raw&quot; value as measured directly by a friction device, and the &quot;normative&quot; value that is derived from the raw one (although I couldn't find any explanation of how). I guess that the raw value is supposed to be the actual &lt;a href=&quot;http://en.wikipedia.org/wiki/Friction#Coefficient_of_friction&quot; rel=&quot;nofollow&quot;&gt;coefficient of friction&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/publication/files/snowtam_harmonisation_guidelines_released_issue_v_2.0.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO format&lt;/a&gt;, on the other hand, is an integer value from 1 to 5. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Incidentally, I'm aware that I'm blurring the distinction between &lt;em&gt;format&lt;/em&gt; and &lt;em&gt;values&lt;/em&gt; here, but since there is so little definite information on this topic available - at least in English - I don't think it matters much.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Russia and CIS AIP includes a &lt;a href=&quot;http://www.caiga.ru/common/AirInter/validaip/aic/aic-2013-06_eng.pdf&quot; rel=&quot;nofollow&quot;&gt;Snow Plan 2013-2014&lt;/a&gt; that states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] friction coefficient will be distributed by means of SNOWTAM in&#xA;  ICAO format (Annex 15)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That immediately suggests that Russia and the CIS now use the ICAO format, and considering the lack of any information about Russian format SNOWTAMs in the AIP or on the web in general, it seems very likely that the ICAO format is now the main or only one in use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Kazakhstan appears to be an exception. There is a &lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/notamRetrievalByICAOAction.do?method=displayByICAOs&amp;amp;reportType=RAW&amp;amp;formatType=DOMESTIC&amp;amp;retrieveLocId=UAAA&amp;amp;actionType=notamRetrievalByICAOs&quot; rel=&quot;nofollow&quot;&gt;permanent NOTAM&lt;/a&gt; for Almaty airport (ICAO: UAAA) in Kazakhstan that includes this remark:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;K0706/13 NOTAMN Q) UAAA/QFBCS/IV/M/A/   /   /4321N07702E A) UAAA B)&#xA;  1312010001 C) PERM E) AT ALMATY AERODROME THE INFORMATION ON RUNWAY&#xA;  BRAKING ACTION IS TRANSMITTED BY ATIS AS FOLLOWS: IN ENGLISH-IN VALUES&#xA;  OF ESTIMATED SURFACE FRICTION RELATIVE TO MEASURED ''SFT'' FRICTION&#xA;  COEFFICIENTS. IN RUSSIAN-IN NUMERICAL VALUES OF NORMATIVE ''RUSSIAN''&#xA;  FRICTION COEFFICIENTS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is a very similar NOTAM for Shymkent (ICAO: UAXX) that includes this almost-but-not-quite-the-same remark:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;K0707/13 NOTAMN Q) UAXX/QFBCS/IV/M/A/   / A) UACC UATT UAII B)&#xA;  1312010001 C) PERM E) AT ALL AERODROMES EXCEPT ALMATY THE INFORMATION&#xA;  ON RUNWAY BRAKING ACTION IS TRANSMITTED BY ATIS OR ATC AS FOLLOWS: IN&#xA;  ENGLISH-IN VALUES OF ESTIMATED SURFACE FRICTION RELATIVE TO NORMATIVE&#xA;  ''RUSSIAN'' FRICTION COEFFICIENTS. IN RUSSIAN-IN NUMERICAL VALUES OF&#xA;  NORMATIVE ''RUSSIAN'' FRICTION COEFFICIENTS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no similar NOTAM for any major Russian airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I put all this information together, it appears that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Russia and the CIS now use the ICAO format for SNOWTAMs&lt;/li&gt;&#xA;&lt;li&gt;Almaty in Kazakhstan reports braking action in the 'raw' Russian format&lt;/li&gt;&#xA;&lt;li&gt;All other Kazakhstan airports report braking action in the 'normative' Russian format&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-09-12T13:34:15.723" LastActivityDate="2014-09-12T13:34:15.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8539" PostTypeId="1" AcceptedAnswerId="8540" CreationDate="2014-09-11T00:50:03.487" Score="6" ViewCount="4975" Body="&lt;p&gt;Do I need a PPL license to get a CPL/ATPL license?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find anything on the net regarding my question.&lt;/p&gt;&#xA;" OwnerUserId="3479" LastEditorUserId="97" LastEditDate="2014-09-11T01:31:30.340" LastActivityDate="2015-07-15T22:32:41.623" Title="Do I need a PPL license for a CPL license?" Tags="&lt;faa-regulations&gt;&lt;ppl&gt;&lt;cpl&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8540" PostTypeId="2" ParentId="8539" CreationDate="2014-09-11T03:00:39.223" Score="11" Body="&lt;p&gt;Yes, with a couple of exceptions. FAR 61.123 contains the requirements for a commercial certificate, while 61.153 contains the requirements for an ATP certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1123&quot;&gt;FAR 61.123(h)&lt;/a&gt; states than an applicant must:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hold at least a private pilot certificate issued under this part or meet the requirements of §61.73&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_173&quot;&gt;FAR 61.73&lt;/a&gt; refers to the option for military pilots to apply for an FAA certificate based on their military qualifications. For non-military pilots, the commercial certificate can only be earned after obtaining the private pilot certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1153&quot;&gt;FAR 61.153(d)&lt;/a&gt; includes the ability to use a foreign commercial or ATP certificate as a prerequisite. An applicant must:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Meet at least one of the following requirements:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Holds a commercial pilot certificate with an instrument rating issued under this part;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Meet the military experience requirements under §61.73 of this part to qualify for a commercial pilot certificate, and an instrument rating if the person is a rated military pilot or former rated military pilot of an Armed Force of the United States; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Holds either a foreign airline transport pilot license with instrument privileges, or a foreign commercial pilot license with an instrument rating, that—&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(i) Was issued by a contracting State to the Convention on International Civil Aviation; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(ii) Contains no geographical limitations.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2014-09-11T03:12:01.793" LastActivityDate="2014-09-11T03:12:01.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8542" PostTypeId="2" ParentId="8539" CreationDate="2014-09-11T09:43:49.847" Score="4" Body="&lt;p&gt;For the European regulations there exist two ways of gaining a CPL:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Way A, also called &quot;modular&quot;: Before being allowed to start your CPL training, a PPL is mandatory + night flying permission. In total you need 150h of flight time out of your PPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Way B, also called &quot;integrated&quot;: A flight school offering modular courses does not neccessarily be able to offer integrated courses, so clarify beforehand. Offering such integrated courses requires special school certification. This course, however, get's you to receive a CPL/IR from pedestrian to commercial pilot without any intermediate stop. Having a CPL, you are authorized to perform the rights of a PPL.&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2014-09-11T09:43:49.847" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8543" PostTypeId="1" AcceptedAnswerId="8673" CreationDate="2014-09-11T12:30:24.837" Score="2" ViewCount="476" Body="&lt;p&gt;In September 2014, Dutch investigators &lt;a href=&quot;https://www.onderzoeksraad.nl/nl/media/inline/2019/1/10/prem_rapport_mh_17_en_interactief2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;published a preliminary report for the MH17 crash&lt;/a&gt;. I understand they based there report on radar records, CVR, FDR and photos and thus can only say the flight goes as expected until multiple impacts from unidentified projectiles came from outside the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought it was easy to identify those projectiles based on fire traces and chemical analysis on remaining wreckage, but it seems they were not able to do such analysis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: what evidence do they have to perform their investigation? If they have wreckage, how can these be pieces coming from the aircraft? Based on the pieces they recovered (and ignoring the political background due to the Ukrainian situation), what kind of conclusion can be expected?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="30128" LastEditDate="2019-03-27T12:51:41.463" LastActivityDate="2019-03-27T12:51:41.463" Title="What pieces of evidence do investigators have access to in the MH17 crash investigation?" Tags="&lt;accident-investigation&gt;&lt;mh17-accident&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8544" PostTypeId="1" AcceptedAnswerId="8549" CreationDate="2014-09-11T13:05:50.063" Score="26" ViewCount="3121" Body="&lt;p&gt;There are many wingtip design, all made to reduce vortex related drag, and neither boeing nor airbus seems to prefer one over another. They move from one design to another at each new aircraft, always claiming the new choice is more efficient than the previous one. In detailed, all generation mixed, it looks like (non exhaustive list):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;winglet: B737NG, A330, B747-400, A320NEO, A350&lt;/p&gt;&#xA;&#xA;&lt;p&gt;wingtip fence: A320, A380, B737MAX&lt;/p&gt;&#xA;&#xA;&lt;p&gt;raked wingtip: B787&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: The other elements of aircraft design are almost the same for all new aircraft (low wing, engines under the wing, classical landing gear, APU in the tail, ...), so I assume it has reached a great level of maturity, nothing has to be improved and introduced on a new aircraft generation. This is obviously not the case for wingtip.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2014-09-11T13:25:52.903" LastActivityDate="2014-09-15T17:33:06.627" Title="Is wingtip design mature?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;winglets&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8545" PostTypeId="2" ParentId="8543" CreationDate="2014-09-11T13:14:02.027" Score="3" Body="&lt;p&gt;I have the impression you are mixing two different types of investigation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;criminal investigation (interested in finding the culprit of a crime)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft Accident and Incident Investigation (whose purpose &lt;code&gt;is the prevention of similar accidents and incidents&lt;/code&gt; cit from &lt;a href=&quot;http://www.onderzoeksraad.nl/uploads/phase-docs/701/b3923acad0ceprem-rapport-mh-17-en-interactief.pdf&quot; rel=&quot;nofollow&quot;&gt;Page 3&lt;/a&gt;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The investigation you cite is of the second kind: they are interested in finding out whether the loss of MH17 was due to some aeronautic-related cause (pilot training, maintenance, manufacture, etc.) and eventually how to avoid similar losses in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this &lt;strong&gt;preliminary&lt;/strong&gt; report they state that the cause of the loss was the impact with several foreign objects. This is a prefectly accebtable conclusion for such investigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You were expecting instead an investigation and a report of the criminal kind. For what I know, you will have to wait quite longer for that.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-09-11T13:14:02.027" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8546" PostTypeId="1" CreationDate="2014-09-11T13:20:46.087" Score="3" ViewCount="986" Body="&lt;p&gt;The introduction of a video recorder in addition to the current audio and flights parameters recorders used for crash investigation (CVR and FDR) is suggested by &lt;a href=&quot;http://www.nytimes.com/2004/07/28/us/board-says-video-black-box-would-help-solve-plane-crashes-pilots-cite-privacy.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt; (published in the New York Times in 2004) citing &lt;em&gt;officials of the National Transportation Safety Board&lt;/em&gt;, and called &lt;em&gt;image recorder&lt;/em&gt; in a &lt;a href=&quot;http://www.ntsb.gov/safety/mwl-7.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;most wanted&lt;/em&gt;&lt;/a&gt; list (published in 2012) of the FAA.&#xA;Those two references shows the introduction of a video recorder is taken seriously. I don't want to debate whether this is usefull neither what should be recorded (wide angle of the whole cockpit, close view of switches and screens, black &amp;amp; white or color, ...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the answers of this &lt;a href=&quot;https://aviation.stackexchange.com/questions/3333/why-dont-both-black-boxes-hold-the-same-data/&quot;&gt;questions&lt;/a&gt;, the video track record's requirements should be very close to the one of the CVR, thus adding this track to the CVR seems reasonable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If we add this video track&lt;/strong&gt; to all tracks recorded by blackboxes, will this records to an existing blackbox (either the FDR or the CVR) or will we create a dedicated blackbox (resulting in three blackboxes)?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;related questions : &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/78418/3394&quot;&gt;Why could increases in cockpit voice and image recording potentially raise privacy concerns?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/48048/3394&quot;&gt;Why doesn't the black box also record video?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2020-05-26T05:46:59.597" LastActivityDate="2020-05-26T05:46:59.597" Title="If we add a video recorder in the cockpit to complete FDR/CVR, will we add a blackbox?" Tags="&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2014-09-11T16:59:53.173" ContentLicense="CC BY-SA 4.0" />
  <row Id="8547" PostTypeId="2" ParentId="8546" CreationDate="2014-09-11T13:46:00.040" Score="0" Body="&lt;p&gt;Before answering, let's look at these terms:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_recorder#Flight_data_recorder&quot; rel=&quot;nofollow&quot;&gt;FDR&lt;/a&gt; - Flight Data Recorder&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FDRs record &lt;em&gt;all&lt;/em&gt; flight data, every button pressed, every control input etc. They record throughout the duration of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_recorder#Cockpit_voice_recorder&quot; rel=&quot;nofollow&quot;&gt;CVR&lt;/a&gt; - Cockpit Voice Recorder&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CVRs record &lt;em&gt;all&lt;/em&gt; voice communications through the radios and the chat pilots have between themselves. They record only the last 30-120 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what benefit will &lt;em&gt;adding a camera&lt;/em&gt; bring?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After an accident (God forbid) the investigators are not interested to see what was the color of pilot's shirt or was he picking his nose before he pressed a button. In addition, you would need several cameras to record every single action of the pilots, and even then it would be hard to figure out as some buttons are placed very close to each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FDRs solve this problem as &lt;em&gt;any&lt;/em&gt; input from the pilots are recorded. CVRs capture &lt;em&gt;all&lt;/em&gt; communications so the motive or reason behind any input from pilots are be found out.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I suggest you to read some NSTB investigation reports (&lt;a href=&quot;https://www.ntsb.gov/investigations/reports.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; or &lt;a href=&quot;http://www.ntsb.gov/aviationquery/month.aspx&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;) to get a detailed idea how in-depth knowledge the investigators can get by these two instruments.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-09-11T13:46:00.040" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8548" PostTypeId="2" ParentId="8544" CreationDate="2014-09-11T14:17:08.037" Score="4" Body="&lt;p&gt;I'm not an aeronautical engineer, so this answer may contain errors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design of an aircraft pretty much &lt;em&gt;is&lt;/em&gt; the design of a wing. The fact that wingtip designs change is only due to the fact that wing design changes with every aircraft type as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuselage design is mature in the sense that circular is better than square. Engine design is mature in the sense that engines are interchangeable; as long as you've got the correct hardpoints on the wing for fuel, bleed air, and so on, it doesn't matter whether you choose to install the Wilbur 400 turbofan or the Orville 602N turbofan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the wing is integral to the aircraft. For each airliner you design, you design a wing to go with it. Center of gravity, center of pressure, critical mach, all of these things and lots more are taken into account and each are different for each aircraft, so they have to be addressed differently. The fact that wingtips differ from model to model only means that wings differ from model to model. &lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-09-11T14:17:08.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8549" PostTypeId="2" ParentId="8544" CreationDate="2014-09-11T15:31:56.950" Score="24" Body="&lt;p&gt;The wingtips are a unique part of the aircraft in that they really have one job; minimize drag. Their design is easy to see, and they are a fairly recent addition to transport aircraft. Developments continue to be made in the study of aerodynamics, with modern computing power and methods allowing much better modeling of flow patterns to evaluate designs, and improvements in materials allowing more complex designs to be built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key is that the winglet must be properly designed. As wing designs change, the flow over the wings changes, and new winglet designs are invented.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it is heavily dependent on the specific application, it's more relevant to look at the evolution of the designs on different aircraft. The design chosen is dependent on the technology available at the time, both for evaluating the design and building it, the design of the wing, intended use of the aircraft, and the previous experience of the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 is an old design that has evolved over time: Original/Classic: none, NG: winglet, P-8: raked tip, MAX: split scimitar&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A330 is a fairly new design: Current: small winglet, neo: winglet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 has also evolved over time, and the latest version shares technology with the 787: Original: none, -400: small winglet, -8: raked tip&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A320 has also evolved over time: Original: none, Current: tip fence, neo: winglet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 is a new design: tip fence&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A350 is a new design: winglet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787 is a new design: raked tip&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 777 is a fairly new design: Basic: none, -200LR and -300ER: raked tips&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice a trend from smaller designs to larger ones. On larger aircraft though, the weight of a large winglet and the loads it produces can get too large. New designs like the 777, A380, 787, and 747-8 all use either raked tips or small winglets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for other parts of aircraft, engines are changing more than you think. The jet engines on the early jet transports look very different from modern high-bypass turbofans. The GEnx engines on the 787 and 747-8 have chevrons at the back to reduce noise. All you see on the outside is the nacelle that minimizes drag; most of the changes go on inside. Also, if you look closely at the front, fan blades on newer engines have curves in them instead of having straight edges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most other parts of the aircraft have more complex jobs, not primarily external. A fuselage should be efficient at carrying things inside but also keep drag low. If you look closely you will notice that new planes like the 787 and A350 have a lot in common with previous fuselages, but they are shaped differently as well. It's harder to see the other drastic changes like the use of composites in place of traditional aluminum, electric systems instead of hydraulic or bleed air, fly by wire, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Control surfaces must provide sufficient control while minimizing drag. The size and shape has also changed over time, though the general design has remained.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-15T17:33:06.627" LastActivityDate="2014-09-15T17:33:06.627" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8550" PostTypeId="1" AcceptedAnswerId="8553" CreationDate="2014-09-11T15:38:26.050" Score="20" ViewCount="12734" Body="&lt;p&gt;I'm working towards my tail wheel rating and enjoying it greatly. But, people ask me why some planes have a conventional landing gear (tail wheel).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why indeed? I understand perhaps why they had them originally, but is it just historical reasons? Seems like maybe it can have slightly lighter gear and perhaps simpler design, but I'm wondering if there are deeper reasons. &lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2017-08-27T05:08:11.113" Title="Why tail wheel rather than tricycle?" Tags="&lt;tail-dragger&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8551" PostTypeId="2" ParentId="8550" CreationDate="2014-09-11T16:14:19.290" Score="12" Body="&lt;p&gt;It's a fiery debate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the reasons for the taildragger design is indeed weight. There is also that the plane will naturally sit at a positive angle of attack and will keep the propeller further off the ground. Rotation is assisted by gravity because the CoG is behind the wheels. Also getting a tailstrike on takeoff isn't critical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons for the nose wheel design is increased control during takeoff (with the tail dragger there is a period where the tailwheel is off the ground and yaw control is up to the rudder)&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-09-11T16:14:19.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8552" PostTypeId="2" ParentId="8539" CreationDate="2014-09-11T17:09:17.703" Score="1" Body="&lt;p&gt;You definitely do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You get your certificates in following order:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;PPL&lt;/li&gt;&#xA;&lt;li&gt;CPL&lt;/li&gt;&#xA;&lt;li&gt;ME&lt;/li&gt;&#xA;&lt;li&gt;ATPL Frozen ( This is actual license for becoming and FO)&lt;/li&gt;&#xA;&lt;li&gt;ATPL ( It means you are eligible to become Captain)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2190" LastActivityDate="2014-09-11T17:09:17.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8553" PostTypeId="2" ParentId="8550" CreationDate="2014-09-11T18:06:37.743" Score="21" Body="&lt;p&gt;Ratchet freak gives already most of the reasons. I might add that on a grass field the taildragger is easier to handle. The relatively high drag and long lever arm of the tailwheel or skid will help to pull the aircraft straight at low speeds when rudder control power is low. On a hard surface, however, the tricycle gear is easier to handle. Also, not only the weight, but also the drag of two wheels is less than that of three.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at modern airplane designs, those where weight must be kept low (like aerobatic planes) still have a taildragger gear. It is also used in gliders and motor gliders, because they will operate mostly from grass strips and do not want to include internal space to accommodate three retractable wheels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Big taildragger designs from the early days vanished with the emergence of concrete runways from the 1930s on and the need to brake more during rollout when wing loadings and landing speeds went up. On concrete runways, the tricycle gear handles better and &lt;a href=&quot;https://aviation.stackexchange.com/questions/16957/is-there-a-good-reason-why-modern-airliners-cant-have-conventional-landing-gear/16962#16962&quot;&gt;gives much better visibility&lt;/a&gt;. Without the ability to brake hard, the rollout lengths of  taildraggers would prohibit todays wing loadings. With retractable gears the drag disadvantage is no more, and the increased weight can be tolerated.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-08-27T05:08:11.113" LastActivityDate="2017-08-27T05:08:11.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8554" PostTypeId="2" ParentId="8544" CreationDate="2014-09-11T18:36:39.127" Score="4" Body="&lt;p&gt;It really doesn't matter that much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at birds: They use two different wingtip designs. I guess we will both agree that those designs are mature after millions of years of evolution. And still there are two distinct wing tip shapes: One is the &quot;fingered&quot; wingtip with large, spread-out feathers, and one is the pointed tip you find from seagulls to albatrosses, and also in swallows. Why is there not one, mature design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has to do with the environment they are used in. Seabirds and swallows fly in an unobstructed environment with steady winds and need to stay aloft for longer duration. All other birds, also lake-dwellers like Pelicans, have to cope with trees obstructing a straight flight path and gusts from hills, or those trees. They need to maneuver quickly and cope with gusty winds. This is helped by a reduced span and the possibility to fold the outer wing in or fan it out in an instance. Hence the fingered wingtip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most aircraft, the seabird solution should work best. But sometimes the environment adds new demands, like span restrictions in the competition classes of gliders. Then it makes sense to add a winglet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another &quot;restriction&quot; is the high cost of developing a new wing, not to speak of the tooling and certification effort. Then it helps to add a winglet so the outer wing can contribute more lift if the aircraft mass is increased by stretching beyond the capabilities of the original wing. But this will drive up wing bending moments disproportionally, so the overall benefit is small. It will always be better for performance to design a new wing with a straight wingtip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you see all kinds of fancy winglets on modern airliners, this has to do more with marketing than with aerodynamics. After all, no bird has winglets. Not a single one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But now picture the Airbus board (full of bean counters and lawyers, and void of aerodynamicists) after Boeing has hyped up their new wingleted wing: The immediate reaction is: We need this wonder device, too! But it must look different! Sadly, this has led to the quasi-religious following of the winglet cult, where winglets are made to be the cure-all of aerodynamic problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now one can argue that nature never came around to try the winglet modification. Not in more than 100 million years, not in one of several independent developments of wings (pterodactyls, insects, birds and bats. You can even add fish to that list, their flippers have a similar function). This could be, but now the question comes down to Occam's Razor: Which is more likely?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Nature never developed winglets, despite their advantages? And please don't call the elastic deformation of tip feathers winglets. This is plain silly.&lt;/li&gt;&#xA;&lt;li&gt;Or Nasa and Boeing marketing have hyped up a device which does improve aerodynamics in some conditions, but is not as good as a straight wing extension if the conditions allow for that extension?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Judge for yourself.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-14T19:05:56.940" LastActivityDate="2014-09-14T19:05:56.940" CommentCount="28" ContentLicense="CC BY-SA 3.0" />
  <row Id="8555" PostTypeId="2" ParentId="8550" CreationDate="2014-09-11T21:04:58.240" Score="3" Body="&lt;p&gt;Some nose wheel gears are fragile and would not survive well on unpaved runways.  Also the distribution of weight is a factor.  There is less weight on a tail wheel than a nose wheel.  Therefore most of the weight of a conventional gear aircraft is split between the mains.  Use of a conventional gear on an soft runway eliminates the issue of the nose wheel digging into the surface.&lt;/p&gt;&#xA;" OwnerUserId="651" LastActivityDate="2014-09-11T21:04:58.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8556" PostTypeId="1" AcceptedAnswerId="55567" CreationDate="2014-09-12T08:10:39.053" Score="57" ViewCount="12758" Body="&lt;p&gt;Is there indisputable evidence that a winglet improves performance over an equal span extension? Please note: I am only interested in L/D improvements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winglets do improve roll performance, that is not what I am looking for. Also, if span is restricted, winglets improve L/D over straight wings. Again, that is not what I am looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing and Airbus use fancy wingtip designs to demonstrate technological sophistication and make incredible-sounding claims about them. This is not the kind of proof I ask for. Is there theoretical or practical evidence comparing winglets with span extensions of equal wetted surface which show that the winglet produces better L/D values at any point of the polar?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus points for a comparison of net lift to drag comparison, so the structural impact of both wing extension and winglet get subtracted from the generated lift. This should be the fairest way to compare both, but it seems such research is not published at all.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-12T12:30:22.963" LastActivityDate="2018-09-29T22:39:32.937" Title="Is a winglet better than an equal span extension?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="8557" PostTypeId="2" ParentId="8556" CreationDate="2014-09-12T09:17:14.200" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www-aa.stanford.edu/Reports/VKI_nonplanar_Kroo.pdf&quot;&gt;This paper&lt;/a&gt; from 2005 states that is not a settled question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the geometric span of the wing is constrained, well-designed winglets do provide significant reductions in airplane drag and have now been incorporated on aircraft ranging from sailplanes to business jets and large commercial transports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(and I understand you agree with the above)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The justification for winglets as opposed to span extensions for aircraft that are not explicitly span-limited is less clear. Studies at NASA Langley that compared these two concepts with constrained root bending moment concluded that winglets were to be preferred over span extensions. (Theoretical parametric study of the relative advantages of winglets and wing-tip extensions - Heyson, 1977 - NASA TP 1020). Studies with constraints on integrated bending moment suggested that the two approaches were almost identical in these respects. (Effect of winglets on the induced drag of ideal wing shapes - Jones, 1980 - NASA NASA TM 81230). A somewhat better weight model (which includes the effects of changes in wing chord on structural efficiency) leads to very similar conclusions as shown in figure 9. &lt;strong&gt;The conclusion is that the complexity of the structural model and constraints limits the general applicability of any such conclusions.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In particular&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The evaluation of optimal winglet height and dihedral, depends on the details of the wing structure, whether the wing is gust critical or maneuver critical, whether large regions of the wing are sized based on minimum skin gauge, and whether the design is new or a modification of an existing design. The evaluation of wing tip device advantages must be undertaken for each design and include an array of multidisciplinary considerations. These include the effect on aeroelastic deflections and loads, flutter speed, aircraft trim, stability and control effects (especially lateral characteristics), off-design operation and effects on maximum lift, and finally, marketing considerations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To conclude:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There is no clear answer to the optimal configuration, and even when winglets are adopted, the geometries vary widely.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What I understand from the above is that if you include no structural or a simple structural limitation, a winglet is better than a span extension (NASA TP 1020 referred above) otherwise you will have to search for a case-by-case answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also &lt;a href=&quot;http://arc.aiaa.org/doi/pdf/10.2514/1.44727&quot;&gt;this other paper&lt;/a&gt; (behind paywall) from 2010 (5 years later than the above paper) that in its abstract reports similar conclusions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When only aerodynamics are considered, closed lifting-surface configurations, such as the box wing and joined wing, are found to be optimal. &lt;strong&gt;When aerostructural optimization is performed&lt;/strong&gt;, a winglet configuration is found to be optimal when the overall span is constrained, and &lt;strong&gt;a wing with a raked wingtip is optimal when there is no such constraint&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2014-09-12T09:17:14.200" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8558" PostTypeId="1" AcceptedAnswerId="8559" CreationDate="2014-09-12T09:33:30.183" Score="6" ViewCount="1906" Body="&lt;p&gt;In case of emergency, an aircraft may have to descend very quickly. Is there some performance (L/D ratio with full spoilers, descent rate, ...) to be proven in the certification process for such descent?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="62" LastEditDate="2014-09-12T13:05:54.787" LastActivityDate="2021-03-16T04:11:55.430" Title="Are there certification requirements for an emergency descent?" Tags="&lt;aircraft-performance&gt;&lt;aircraft-certification&gt;&lt;descent&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8559" PostTypeId="2" ParentId="8558" CreationDate="2014-09-12T13:20:22.363" Score="7" Body="&lt;p&gt;There is a descent requirement, but it's perhaps not in the way you imagine as it has to do with oxygen supply. &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY%5CRGFAR.NSF/0/5A99C617262EF7AB862570D70078AE87?OpenDocument&quot;&gt;FAR 122.333&lt;/a&gt; subpart K states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Crewmembers. When operating at flight altitudes above 10,000 feet,&#xA;  the certificate holder shall supply enough oxygen to comply with&#xA;  §121.329, but not less than a two-hour supply for each flight&#xA;  crewmember on flight deck duty. The required two hours supply is that&#xA;  quantity of oxygen necessary for a constant rate of descent from the&#xA;  airplane's maximum certificated operating altitude to 10,000 feet in&#xA;  ten minutes and followed by 110 minutes at 10,000 feet. The oxygen&#xA;  required in the event of cabin pressurization failure by §121.337 may&#xA;  be included in determining the supply required for flight crewmembers&#xA;  on flight deck duty.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This specifies that a turbine aircraft must be able to descend from it's maximum certificated altitude to 10,000ft in 10 minutes or less. This means the maximum descent speed is variable to maximum certificated altitude, so if an aircraft's ceiling is 42000ft it must be able to descend at least 3200fpm, it it's 25000ft then 1500fpm. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how that's done I don't think the regulations say, it's up to the manufacturers to develop aircraft that can meet the requirement. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-09-12T13:20:22.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8560" PostTypeId="1" AcceptedAnswerId="8562" CreationDate="2014-09-12T13:31:14.213" Score="20" ViewCount="7048" Body="&lt;p&gt;Helicopters need a tail rotor to balance the torque reaction that tends to rotate the main body sideways. Doesnt a single-engine plane suffer the same problem? I would imagine that (for example) the left wing would dip lower than the right due to the torque. How is it countered?&lt;/p&gt;&#xA;" OwnerUserId="3136" LastActivityDate="2015-08-07T14:26:04.637" Title="Do aeroplanes have to balance torque like helicopters?" Tags="&lt;helicopter&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8561" PostTypeId="2" ParentId="8560" CreationDate="2014-09-12T13:34:53.963" Score="4" Body="&lt;p&gt;It is countered by the natural stability and the roll control provided by the ailerons. If you have insufficient airspeed for roll control then you will be on the ground and your gear will prevent excessive rolling.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-09-12T13:34:53.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8562" PostTypeId="2" ParentId="8560" CreationDate="2014-09-12T14:00:56.420" Score="19" Body="&lt;p&gt;A single engine plane can suffer from control problems due to torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An early famous example was the &lt;a href=&quot;http://www.youtube.com/watch?v=u3DXEsC4Pq8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sopwith Camel&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have pointed out, torque effects have to be countered using the normal aerodynamic controls available to the pilot. Some aircraft had extra-large ailerons because of this issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avstop.com/ac/flighttrainghandbook/forces.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gvXr4.jpg&quot; alt=&quot;DIagram showing torque effects on aircraft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-12T15:44:58.320" LastActivityDate="2014-09-12T15:44:58.320" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8563" PostTypeId="2" ParentId="8560" CreationDate="2014-09-12T14:45:30.667" Score="9" Body="&lt;p&gt;In contrast to what happens in helicopters, the static and dynamic stability will prevent big movements of propeller aircraft due to engine and propeller torque. The biggest consequence, the rolling moment, is taken care of by roll damping. When the propeller torque rolls the aircraft, the downwards-moving wing will see a higher, and the upwards-moving wing a lower angle of attack. Both wings will create a rolling moment which will quickly stop the rolling motion. All the pilot has to do is to restore the correct roll attitude using the ailerons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift difference of the rolling aircraft also creates different drag on the left and right wings, so a small yawing moment will turn the aircraft slightly sideways when the rolling starts. This has to be corrected by rudder input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at other secondary effects, the yawing motion will cause a slight pitch change by way of engine and propeller precession. This also will be stopped quickly by pitch damping (the pitch movement changes the angle of attack on the horizontal tail surfaces), and the pilot needs to correct the pitch attitude again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In consequence, changing RPM will induce slight movements around all three axes in a single-engined propeller airplane.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-12T14:45:30.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8564" PostTypeId="2" ParentId="8558" CreationDate="2014-09-12T16:13:47.957" Score="5" Body="&lt;p&gt;In addition to oxygen supplies, there are also regulations about cabin pressure. The descent rate required can be determined by the probability of decompression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;FAR §25.841&lt;/b&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If certified to operate above 25,000 feet, cabin pressure altitude must be less than 15,000 feet &quot;after any probable failure condition in the pressurization system.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For &quot;any failure condition not shown to be extremely improbable:&quot; the cabin altitude is limited to 25,000 feet for 2 minutes, and is not allowed to exceed 40,000 feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So for any &quot;probable&quot; failure, the aircraft must be able to descend to 15,000 feet before the cabin pressure is completely lost. For any failure not &quot;extremely improbable,&quot; the aircraft must be able to descend to 25,000 feet within 2 minutes of losing all cabin pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These probabilities are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Probable: more than 10&lt;sup&gt;-5&lt;/sup&gt; (1/100,000)&lt;br&gt;&#xA;Extremely improbable: less than 10&lt;sup&gt;-9&lt;/sup&gt; (1/1,000,000,000 or &quot;not anticipated to occur during the entire operational life of all airplanes of one type&quot;)&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-12T19:12:27.037" LastActivityDate="2014-09-12T19:12:27.037" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8565" PostTypeId="1" AcceptedAnswerId="8570" CreationDate="2014-09-12T18:22:58.613" Score="10" ViewCount="2020" Body="&lt;p&gt;Near the end of the 50s Sci-Fi movie &lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/This_Island_Earth&quot; rel=&quot;noreferrer&quot;&gt;This Island Earth&lt;/a&gt;&lt;/strong&gt;, the protagonist is escaping from a flying saucer which is crashing to Earth. As he was abducted while flying a plane (specifically a &lt;a href=&quot;https://en.wikipedia.org/wiki/Stinson_108&quot; rel=&quot;noreferrer&quot;&gt;Stinson 108-1&lt;/a&gt;), it's sitting in the cargo hold on top of a retracting hatch:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cWxf2.jpg&quot; alt=&quot;Image of the Stinson 108-1 in a flying saucer hangar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The protagonists then start up the propeller, and once it gets up to speed, the entire hatch seems to disappear and they're dropped vertically out of the bottom of the flying saucer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a1S2G.jpg&quot; alt=&quot;Image of the Stinson 108-1 after leaving the flying saucer&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They then manage to continue moving straight without going into any kind of dive, before banking out of the shot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this even remotely possible? I would have assumed that when they leave the system of the flying saucer, they will lose the speed which the saucer has and will basically be falling in a stationary position as they have no lift due to the air only hitting the bottom of the wings.&lt;/p&gt;&#xA;" OwnerUserId="3488" LastActivityDate="2015-04-09T14:56:32.573" Title="Can single engine planes glide from a falling position?" Tags="&lt;single-engine&gt;" AnswerCount="6" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8566" PostTypeId="2" ParentId="1087" CreationDate="2014-09-12T18:34:40.350" Score="3" Body="&lt;p&gt;. A LPV approach can provide WAAS vertical guidance as low as 200 feet AGL. &#xA;LNAV/VNAV approaches also provide approved vertical guidance and existed &#xA;before the WAAS system was certified. At that time, only aircraft equipped with &#xA;a flight management system (FMS) and certified baro-VNAV systems could use &#xA;the LNAV/VNAV minimums.&#xA;Also the design of an LPV approach incorporates angular guidance with increasing sensitivity &#xA;as an aircraft gets closer to the runway. (This is intentional to aid &#xA;pilots in transferring their ILS flying skills to LPV approaches). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/factsheets/media/RNAV_QFacts_final_06122012.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/factsheets/media/RNAV_QFacts_final_06122012.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3490" LastActivityDate="2014-09-12T18:34:40.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8567" PostTypeId="2" ParentId="1087" CreationDate="2014-09-12T18:55:55.077" Score="14" Body="&lt;p&gt;There's an &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/factsheets/media/RNAV_QFacts_final_06122012.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA paper&lt;/a&gt; on RNAV approaches that explains the differences between LP, LPV, LNAV and LNAV/RNAV approaches. I made a table for my own reference but since StackExchange doesn't allow tables (AFAIK) here's a summary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LP: no vertical guidance; WAAS required; MDA for minimums&lt;/li&gt;&#xA;&lt;li&gt;LPV: vertical guidance; WAAS required; DA for minimums&lt;/li&gt;&#xA;&lt;li&gt;LNAV: no vertical guidance; WAAS not required; MDA for minimums; requires RAIM integrity if WAAS is not available&lt;/li&gt;&#xA;&lt;li&gt;LNAV/VNAV: vertical guidance; WAAS or baro-VNAV required; DA for minimums; requires RAIM integrity if WAAS is not available (i.e. if using baro-VNAV); possible temperature restrictions if using baro-VNAV&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The difference between LPV and LNAV/VNAV is that although they both have vertical guidance, LPV was intentionally designed to be very similar to an ILS approach with an increasingly sensitive glideslope whereas LNAV/VNAV was not. Other answers have additional comments about LNAV/VNAV having been designed earlier and for different equipment which would certainly make sense.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-10-05T14:10:40.790" LastActivityDate="2015-10-05T14:10:40.790" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8568" PostTypeId="2" ParentId="8565" CreationDate="2014-09-12T19:04:22.540" Score="10" Body="&lt;p&gt;The sequence you describe are plausible but not without a dive and some turbulence shaking the aircraft as it clears the  wake of the UFO. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The principle it uses is conservation of momentum:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the UFO the aircraft has the same speed as the UFO. If you take away the air (and drag, lift and propulsion) and drop the plane from the hatch; the plane would follow a parabolic arc while the UFO stays right above it supported by sci-fi magic right up until it crashes into the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if we add air and assume the UFO is going at cruising speed of the plane then after it clears the turbulent area of the UFO it will have enough airspeed to maintain lift and fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turns out that aircraft have launched from an airship, for example the &lt;a href=&quot;http://en.wikipedia.org/wiki/USS_Macon_%28ZRS-5%29&quot;&gt;USS Macon&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/USS_Akron_%28ZRS-4%29#Experimental_use_as_a_.22flying_aircraft_carrier.22&quot;&gt;USS Akron&lt;/a&gt; launching &lt;a href=&quot;http://en.wikipedia.org/wiki/Curtiss_F9C_Sparrowhawk&quot;&gt;sparrowhawks&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/23-class_airship&quot;&gt;23-class airship&lt;/a&gt; was able to launch planes during tests. The launch from the USS Macon involved lowering the aircraft into the airstream below the zeppelin and then letting it go though there there was enough horizontal speed from the airship itself to achieve proper flight after only a short dive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a suspended drop from a stationary point the plane needs to be able to pitch down while in a vertical drop while in a horizontal attitude. And then achieve enough airspeed to not stall when leveling out. Most aircraft are designed to point nose down while in free-fall. &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-09-12T19:11:40.657" LastActivityDate="2014-09-12T19:11:40.657" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8569" PostTypeId="1" CreationDate="2014-09-12T19:06:37.483" Score="21" ViewCount="6073" Body="&lt;p&gt;I understand that the radar sends a 1030 MHz interrogation signal to an aircraft and the aircraft's transpoder responds using 1090 MHz. When it comes to Mode S squitter, the transmissions are unsolicited (does not require interrogation). Considering that the airspace is highly populated, there would be multiple aircrafts transmitting data on the 1090 MHz to the radar. Won't these signals interfere with each other and become a huge mess at the radar side? &#xA;(Similar is the case of ADS-B, where data would be continuously broadcasted between aircraft-aircraft, aircraft-ATC and vice versa on the 1090 MHz Extended Squitter, how are the signals prevented from mixing up with each other?) &#xA;&lt;br&gt;&#xA;Also how is the interrogation signal transmitter from ATC to aircraft (and also back) sent? Is Frequency modulation used here? What is the bandwidth of the 1090 Mhz channel? Does it have sidebands?&lt;/p&gt;&#xA;" OwnerUserId="3491" LastEditorUserId="7532" LastEditDate="2015-11-17T04:15:49.827" LastActivityDate="2015-11-17T04:15:49.827" Title="How does ATC radar/ADS-B ground stations not get confused with signals sent from multiple aircraft?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;&lt;ads-b&gt;&lt;transponder&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8570" PostTypeId="2" ParentId="8565" CreationDate="2014-09-12T19:08:27.223" Score="16" Body="&lt;p&gt;It's remotely possible, assuming you can find a suitable UFO :-) If you drop an object from an aircraft it starts falling with the same airspeed that the aircraft has, until drag or other factors slow it down. If you've ever seen a flour bombing competition (or just watched some WW2 movies or documentaries) you may have noticed that you drop bombs before you reach the target, not when you arrive directly over it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the UFO is moving forward at an airspeed greater than the Stinson's stalling airspeed (65mph) - let's say 80mph - then the Stinson will fall into the air at an airspeed high enough to generate lift immediately and it will fly. If you already have the engine running and throttle up as soon as you fall out of the UFO, you will generate thrust and maintain the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality - if there is such a thing when a UFO is involved - the Stinson is almost certain to lose some altitude and the wake turbulence from the much larger UFO will have a significant (and potentially very dangerous) effect if the Stinson can't stay ahead of it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-09-15T15:17:27.803" LastActivityDate="2014-09-15T15:17:27.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8571" PostTypeId="2" ParentId="8569" CreationDate="2014-09-12T21:40:23.173" Score="20" Body="&lt;p&gt;The class of ATC radars that you are talking about is secondary radar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondary radar works by transmitting an interrogation signal on 1030 MHz to which the transponder replies on 1090MHz. There are several modes of interrogation. For civil ATC, modes A,C and S are important. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The uplink signal (interrogation) is a simple pulse encoding (Mode A/C) or a Differential Phase Shift Key modulation (Mode S / TCAS) on 1030 MHz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downlink signal (replies, unsolicited squiters) is a simple pulse encoding (Mode A/C) or Pulse Position Modulation (Mode S / TCAS / ADS-B)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally only Mode A &amp;amp; C were available. Mode A and Mode C are unaddressed; every transponder receiving a Mode A or Mode C interrogation will reply*. This causes two problems,  &lt;em&gt;garbling&lt;/em&gt; and &lt;em&gt;FRUIT&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Garbling&lt;/em&gt;&lt;/strong&gt; is caused by the overlap of replies from multiple transponders. A transponder replies on 1090 MHz in the from of a number of pulses. For Mode A &amp;amp; C, there are at most 12 pulses between a set of framing pulses. When multiple aircraft reply to the same interrogation, these pulses mix up and it becomes difficult to find out which transponder sent which pulse. This leads to false altitudes or false squawk codes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;FRUIT&lt;/em&gt;&lt;/strong&gt; (False Replies Unsynchronised to Interrogator Transmission) is caused by replies that are triggered by other radars. When multiple radars operate in an area, transponders can be quite busy and the radar is easily mislead by a reply to another radar. In addition to the timing (range) being wrong, the reply can be Mode A (squawk code) while the radar interrogated Mode C (altitude). There is no way to see what kind (A or C) reply was sent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To overcome these problems of Mode A/C, Mode S was introduced. Mode S is quite different from Mode A/C and requires a more sophisticated radar and transponder. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Most Mode S interrogations are addressed; the interrogation contains the unique 24 bit address of the aircraft it is interrogating. This reduces the probability of garbling since other aircraft will not reply&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unaddressed Mode S interrogations will solicit replies that contain the address of interrogator (radar). This prevents FRUIT since the radar can verify that the reply is correctly addressed. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unlike Mode A/C which does not have any error checking, a Mode S reply contains a 24 bit CRC check code. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Mode S Altitude and identity (squawk) replies have their own identifier so they can be distinguished.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Mode S radars can be operated in clusters and coordinate between them  who is interrogating which aircraft at which time. This further reduces the message load and garbling / fruit probability.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Despite all the enhancements,  Mode S radars are still receiving garbled messages and FRUIT, but are much better equipped to cope with it than a Mode A/C radar due to the addressing and CRC checks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since TCAS works on the same frequency as secondary radar, radars will occasionally receive TCAS messages as well. But since these have another downlink format (DF 0, DF 16) they are ignored. The same holds for ADS-B (DF 17 / 18) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Garbling remains a concern. Modern Mode S radars are relatively resilient against garbling due to their narrow beamwidth and advanced degarbling processors. But other systems like TCAS, ADS-B in and Wide Area Multilateration systems with their omnidirectional antennas receive overlapping messages quite often. But when the signal strength of the messages differs the messages can be often untangled with modern digital signal processors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Mode S (&amp;amp; TCAS) a reply can be either short (56 bit) or long (112) bit. ADS-B messages are 112 bit long. Every bits takes  1μs, and there is a preamble that takes 8μs. So a message takes either 64μs or 120μs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every second, a Mode S transponder sends 1 unsolicited short squitter, and at most 6.2 long squitters when ADS-B equipped.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;*To reduce number of Mode A/C replies, Mode S radars will include an extra pulse when interrogating in Mode A or C, so that Mode S capable transponders will not reply to these A/C interrogations. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-09-12T22:08:35.407" LastActivityDate="2014-09-12T22:08:35.407" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8572" PostTypeId="2" ParentId="8565" CreationDate="2014-09-12T23:21:52.100" Score="7" Body="&lt;p&gt;It's quite possible. For videos, look for the X-series tests done by NASA at Edwards AFB. They've been dropping functional, manned aircraft from a B-52 since the late 1940s. Most famous examples are the X-1 (Yaeger's flight breaking the sound barrier) and the X-15. In the videos the dropped aircraft keeps pace with the bomber until they start the engine and rapidly pull ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early free-flight tests of the Space Shuttle were the other way up - the shuttle was released from the top of a 747 and flew away without incident. Maybe not quite identical as it was already &quot;in flight&quot; at the time.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;they have no lift due to the air only hitting the bottom of the wings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's where 100% of your lift comes from. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-09-12T23:21:52.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8573" PostTypeId="2" ParentId="8565" CreationDate="2014-09-13T04:57:58.597" Score="1" Body="&lt;p&gt;The other answers given are good, but just wanted to add a few things.  First, the starting velocity of the UFO is the starting velocity of UFO is the starting velocity of the plane.  If the the UFO is going in the +X direction (let's say to the right) at speed v, then if the plane is pointed in the +X direction it will start moving forward at v.  The thrust of the propellers should then propel the aircraft as if it were accelerating from speed v.  If v is above stall speed (as stated above) then it will start in controlled flying regime.  If v is below stall speed, the plane should still have enough control authority (from it's own generated thrust) to pitch down to accelerate to a speed high enough to fly correctly - if the altitude is high enough of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even more fun to think about might be if a modern fifth generation fighter was dropped out.  These fighters have thrust vectoring which in reality could stop the descent and accelerate forward.  The F-22 has a stunt like this in it's airshow routine and it is quite impressive.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-09-13T04:57:58.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8574" PostTypeId="1" CreationDate="2014-09-13T10:03:01.910" Score="2" ViewCount="208" Body="&lt;p&gt;In lots of commercial and defence aircrafts, bleed fault is annunciated because of mainly the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Overpressure/Overheat&lt;/li&gt;&#xA;&lt;li&gt;shut-off valve disagreement (i.e. failed open, failed closed)&lt;/li&gt;&#xA;&lt;li&gt;pressure regulator shut-off valve fails&lt;/li&gt;&#xA;&lt;li&gt;Precooler fails&lt;/li&gt;&#xA;&lt;li&gt;Computer failure&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;However, when there is an emergency condition e.g. engines are lost/off/unavailable (i.e. no generators) and also no APU possible, should there be any bleed fault? Given that the aircrafts are only running on batteries, should there be a bleed fault because your sensors and computers aren't powered up completely? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that you have things like built-in autotest stuff that goes on before the computers are powered, but surely when the aircraft is on batteries/emergency power, should there be any bleed faults?&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="2695" LastEditDate="2014-09-13T10:32:46.227" LastActivityDate="2014-11-16T21:23:56.093" Title="BLEED FAULT lamp illumination under various conditions" Tags="&lt;emergency&gt;&lt;unpowered&gt;&lt;apu&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2014-11-17T13:59:47.207" ContentLicense="CC BY-SA 3.0" />
  <row Id="8575" PostTypeId="2" ParentId="8565" CreationDate="2014-09-13T10:29:34.793" Score="1" Body="&lt;p&gt;Sure, if the UFO is moving forward at something close to the stall speed of the Stinson then it would drop, have a momentary bump as it goes through the air boundary of the UFO, then fly away. The airplane is dropped in its landed attitude, with the tail on the ground, so the pilot would need to very quickly get the nose down. I would expect Dr Meacham, genius as he is, would think about this ahead of time and be prepared, perhaps having some forward stick applied as the floor disappears. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the UFO is stationary then it's a bit more complex, but it could still work. The aircraft is dropped with the tail down and no forward speed. The majority of the air flow at first would be from the propeller, which would give the pilot some elevator and rudder authority. If he applied full forward stick right away he might be able to get the nose down quickly enough that the airplane would quickly build up some airspeed and start normal flight. If he wasn't able to get the nose down before the plane drops then it would most likely go into some sort of spin, which would be recoverable. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-09-13T10:29:34.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8577" PostTypeId="1" AcceptedAnswerId="8578" CreationDate="2014-09-13T11:23:24.977" Score="12" ViewCount="2669" Body="&lt;p&gt;On some GA aircraft such as the Piper Malibu, the propeller would touch the ground if the gear was up. How would you land the plane when gear actuators fail?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would pull out the mixture knob and turn off magnetos, so the propeller is stopped when it touches the ground, but what is the official/best way to do this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can assume the propeller is constant-speed.&lt;/p&gt;&#xA;" OwnerUserId="3493" LastEditorUserId="3386" LastEditDate="2015-03-22T09:16:52.813" LastActivityDate="2015-03-22T12:35:49.017" Title="How to execute a gear up landing on aircraft with low propeller?" Tags="&lt;landing&gt;&lt;general-aviation&gt;&lt;landing-gear&gt;&lt;propeller&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8578" PostTypeId="2" ParentId="8577" CreationDate="2014-09-13T15:22:13.367" Score="22" Body="&lt;p&gt;Not only some, but in fact most GA propeller-driven aircraft have propellers that extend below the bottom of the fuselage. (The only exception that quickly comes to mind is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_Skymaster&quot;&gt;Cessna Skymaster&lt;/a&gt;; I'm sure there are plenty of others.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the aircraft will have some secondary method of gear extension, such as gravity drop, a manual crank, or a blow-down bottle. But there are still times where the gear cannot be extended and locked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this situation, you've got one emergency. Don't make it two emergencies by shutting down your engine. There's an aphorism - &quot;If the gear fails, the insurance company just bought the airplane.&quot;&lt;sup&gt;1&lt;/sup&gt; Without gear, you're going to do some damage: scraped belly, probably tearing off some antennas. The aircraft will already require maintenance; the extra time and cost of an engine teardown is insignificant compared to the increased risk from a higher workload and a landing that the pilot may not have ever practiced before. (The approach with gear up and engine out will be different than that with gear down and engine at idle in a simulated engine failure.) &lt;strong&gt;Don't risk your life to save the insurance company money.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, just stopping the engine isn't sufficient to prevent a teardown. You must also rotate the prop so that it's horizontal, which requires slowing substantially as you pull the mixture to stop it from windmilling, and then using the starter to move the prop.&lt;sup&gt;2&lt;/sup&gt; You'd need to prevent any substantial contact between the propeller and runway, as &lt;a href=&quot;http://www.lycoming.com/Portals/0/techpublications/servicebulletins/SB%20533B%20%2810-04-2012%29/Recommended%20Action%20for%20Sudden%20Engine%20Stoppage,%20Propeller-Rotor%20Strike%20or%20Loss....pdf&quot;&gt;Lycoming's Service Bulletin&lt;/a&gt; on propstrikes that require inspection and repair (Continental's is similar) includes the situation of &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Any incident, whether or not the engine is operating, where repair of the propeller is necessary&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After all of that, there are some best practices:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Declare an emergency. ATC will help you, have equipment ready on the ground, and clear traffic around you - but they need to know about it first.&lt;/li&gt;&#xA;&lt;li&gt;Use your checklist. An airplane with retractable gear will have an entry for gear failure; follow it. In particular, you'll shut down the electrical system before landing, and probably brace open a door for exit.&lt;/li&gt;&#xA;&lt;li&gt;Land on a paved surface. Dirt or grass may seem softer, but they aren't as smooth. According to &lt;a href=&quot;http://flighttraining.aopa.org/magazine/1999/February/199902_Gearup_Landings_Asphalt_or_Grass.html&quot;&gt;an AOPA flight-training newsletter&lt;/a&gt;, &quot;Statistics suggest that putting the airplane on the asphalt is likely to cause less damage to you and your airplane than putting it on the grass.&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(1) I've also heard &quot;The insurance company buys the aircraft when you take off; when you land safely, you buy it back.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Or you could do it in the flare - a suggestion so dangerous I include it only for completeness.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2014-09-13T15:28:11.563" LastActivityDate="2014-09-13T15:28:11.563" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8579" PostTypeId="2" ParentId="8556" CreationDate="2014-09-13T17:06:27.387" Score="50" Body="&lt;p&gt;Here is what I think you need to come to your own conclusion. First I will give a very general overview over lift creation, and then I will look at three wings:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;An unmodified wing&lt;/li&gt;&#xA;&lt;li&gt;This wing plus a winglet&lt;/li&gt;&#xA;&lt;li&gt;This wing plus the winglet, but this time folded down into the plane of the wing.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For each I will plot the lift and bending moment distribution. I will assume an elliptic circulation, fully knowing that this is not what most aircraft use. But I have to pick a distribution to make all three cases comparable, and the elliptic one makes things easier. The conclusions can be generalized for other distributions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will be a lengthy post (you should know me by now), so thanks to all who persevere through all of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Lift creation and induced drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This topic &lt;a href=&quot;https://aviation.stackexchange.com/questions/3428/do-box-wings-suffer-from-induced-drag-the-same-way-as-normal-wings/3467#3467&quot;&gt;had&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;been&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529#7529&quot;&gt;covered&lt;/a&gt; before, and I mention it again to show a very simple and elegant way to explain induced drag that does not need vortices. I want to dispel the myth that induced drag is caused by air flowing around the wingtip, and winglets somehow magically can suppress this flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a wing with elliptic circulation over span (think of circulation as the product of the local lift coefficient $c_l$ and local chord; it is basically the lift per spanwise increment). The wing bends the air through which it flows slightly downwards, and creates an opposite upwards force, namely lift (Newton's second law). I choose an elliptic distribution because then the downwash is constant over span, which makes the following calculations easier.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/TWcEs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sheet of air coming off behind the wing looks trough-shaped and moves downwards, thereby pressing other air below out of the way and allowing air above to flow inwards and to fill up the vacated volume. &lt;strong&gt;That&lt;/strong&gt; is how the free vortex is created, and air flowing around the wingtips has only a small part in this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Induced drag is the consequence of the wing bending the airflow downwards. To simplify things, let's assume the wing is just acting on the air with the density $\rho$ flowing with the speed $v$ through a circle with a diameter equal to the span $b$ of the wing. If we just look at this stream tube, the mass flow is $$\frac{dm}{dt} = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift $L$ is then the impulse change which is caused by the wing. With the downward air speed $v_z$ imparted by the wing, lift is: $$L = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v\cdot v_z = S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$S$ is the wing area and $c_L$ the overall lift coefficient. If we now solve for the vertical air speed, we get $$v_z = \frac{S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho}{\frac{b^2}{4}\cdot\pi\cdot\rho\cdot v} = \frac{2\cdot c_L\cdot v}{\pi\cdot AR}$$&#xA;with $AR = \frac{b^2}{S}$ the aspect ratio of the wing. Now we can divide the vertical speed by the air speed to calculate the angle by which the air has been deflected by the wing. Let's call it $\alpha_w$: $$\alpha_w = arctan\left(\frac{v_z}{v}\right) = arctan \left(\frac{2\cdot c_L}{\pi\cdot AR}\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deflection happens gradually along the wing chord, so the mean local flow angle along the chord is just $\alpha_w / 2$. Lift acts perpendicularly to this local flow, thus is tilted backwards by $\alpha_w / 2$. In coefficients, lift is $c_L$, and the backwards component is $\alpha_w / 2 \cdot c_L$. Let's call this component $c_{Di}$: $$c_{Di} = arctan \left(\frac{c_L}{\pi\cdot AR}\right)\cdot c_L$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small $\alpha_w$s the arcus tangens can be neglected, and we get this familiar looking equation for the backwards-pointing component of the reaction force: $$c_{Di} = \frac{c_L^2}{\pi\cdot AR}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the circulation over span has an elliptic distribution, the local change in circulation times the local amount of circulation is constant, and the induced drag $c_{Di}$ is at its minimum. If this would be different, a higher local $v_z$ causes a quadratic increase in local induced drag, so the whole wing will create its lift less efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we know we can calculate induced drag and we understand why the vortex sheet behind the wing rolls up, producing two counter-rotating vortices, all without looking at the details of the wingtip. What counts is that the wing is of finite span, so the stream tube which is influenced by the wing is of finite diameter as well. Of course, in reality there is no clear boundary between air which is affected by the wing and other air which is not. There is a diffuse transition the more one moves away from the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Comparison of wingtips&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First the geometries: Here are three wingtips in top and front views for comparison:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/fSpns.png&quot; alt=&quot;views of tree wingtips in comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's look at the circulation distribution of the simple wing tip:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/e9iHf.png&quot; alt=&quot;circulation_wing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, I choose the elliptic distribution for simplicity. The corresponding bending moment looks like that:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/PrbHp.png&quot; alt=&quot;bending_moment_wing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No surprises so far. Now we add a winglet and make it work as best as possible. This means we have to give it an angle of attack where it carries the circulation from the wing over on the winglet and completes the elliptic tapering of circulation down to 0 at the tip:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/AfCRf.png&quot; alt=&quot;circulation_winglet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The grey dashed line is the circulation of the original wing. I adjusted the circulation such that both wings produce the same lift. $b_{WL}$ is the span at the winglet tip, and for the bending moment plot I have folded the spanwise coordinate down on the y axis:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/rS78i.png&quot; alt=&quot;bending_moment_winglet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the bending moment starts at the wingtip with a nonzero value. Since the sideways force of the winglet is parallel to the wing spar, this bending moment contribution is constant over span. But there is more: Now also circulation at the old wingtip location is nonzero, and we get a substantial lift increase at the outer wing stations. This effect is what causes the additional lift and gives the better aileron response that winglets make possible. But it also increases the root bending moment, because this additional lift acts with the lever arm of the outer wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can we compare the induced drag of the wing with winglets to the original wing? The circulation gradient is lower, that helps. Also the diameter of that stream tube is larger, but it is hard to say by how much. The sideways force on the winglet is created by pushing the vortex sheet aft of the winglet sideways out, so the trough-shaped area should become wider. &lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/OPerA/OPerA_PUB_DLRK_12-09-10.pdf&quot; rel=&quot;noreferrer&quot;&gt;Empirical evidence&lt;/a&gt; hints at an increase in diameter of 45% of the winglet span (see chapter 6 for a discussion of several papers on the topic).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just for the heck of it, let's assume that the diameter really increases in line with winglet span. Then let's compare that to the straight wing extension, where the same diameter can be assumed with much more certainty:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/h7Ss0.png&quot; alt=&quot;circulation_extension&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now also the lift on the folded-down winglet acts upwards, so the circulation at the center of the wing can be reduced even further. However, now it adds a linearly increasing part to the bending moment, and the outer wing section creates more lift, as before with the wing with winglet:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/GdeAK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here, the root bending moment is higher than in the winglet case. This is a second advantage of winglets: They allow to increase maximum lift with less bending moment increase than a wing extension. But the wing extension puts all parts towards the creation of lift, and not some to the useless creation of side force. Both the extended and the winglet-wing have the same surface friction and (when we assume the same diameter of the hypothetical stream tube) the same induced drag. But since the winglet creates some side force, the remaining wing needs to fly at a higher lift coefficient. Also, the intersection of wing and winglet might be as well rounded as possible, this is where early separation starts at higher angles of attack. None of this affects the straight wing extension.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most evidence shows that winglets improve L/D over the original wing, but folding the winglet down will more than double its effectiveness in lowering drag. Even if we assume that the winglet is just as good as an equal span extension, still the span extension comes out ahead in L/D improvement because all its lift contributes to overall lift, whereas the winglet produces a side force instead. If no separation occurs at the wing-winglet intersection, both will create the same induced and profile drag (pressure and friction), because both have the same wetted surface and the same local circulation. Again, this gives winglets the benefit of equally low induced drag, which is not supported by most measurements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extended wingtip in the example above has interesting characteristics. It is a sweptback (raked) wingtip, which causes the local lift curve slope to be lower than that of the straight wing. This increases its maximum angle of attack and  - assuming that the local area is bigger than what an elliptic wing shape would dictate - makes it possible to keep a nearly elliptic circulation distribution over a wider angle of attack range. The bigger local area is a sensible precaution against the wing tip stalling first, so a raked wing tip will combine benign stall characteristics and very low induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this to the winglet, which has to be tailored for one polar point: Since changes in wing angle of attack will not change the incidence of the winglet, it cannot adapt as well to different flow conditions as can the extended wing. In sideslip the winglet will mess up the circulation distribution on the wingtip and will act like a deflected spoiler.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing equal winglets and wing extensions gives these basic characteristics:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Both have the same viscous drag at low angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;Both can create more maximum lift, and both lower induced drag.&lt;/li&gt;&#xA;&lt;li&gt;The wing extension can create most lift for the given increase in wetted surface.&lt;/li&gt;&#xA;&lt;li&gt;The wing extension is more than twice as effective in lowering induced drag.&lt;/li&gt;&#xA;&lt;li&gt;The wing extension gives a better circulation distribution at off-design angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;The wing extension produces the highest root bending moment for a given amount of lift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How much the bending moment increase will drive up structural mass depends on the aspect ratio of the original wing. Low aspect ratio wings will not suffer much, but stretching high aspect ratio wings will drive up spar mass considerably. But please note that the winglet also causes higher root bending moments, and it creates less bending moment than the wing extension because it creates some side force instead of pure, useful lift.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-11-29T22:08:22.297" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="8580" PostTypeId="1" AcceptedAnswerId="15089" CreationDate="2014-09-13T19:14:23.700" Score="7" ViewCount="32418" Body="&lt;p&gt;I'm stuck on the following riddle found on the geocaching web site:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A helicopter pilot is flying at an altitude of 1981 meters. He is heading inbound an airfield 335 meters high. There are no particular obstacles (such as mountains, ...) between the helicopter and the airfield. What maximal distance (in nautical miles) can the pilot expect in order to be able to communicate with the airfield control tower?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately I don't know anything about air control rules and multiple Google searches came to no avail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please could you give me a clue (not the answer as it would spoil the fun) how to answer this riddle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who are interested here is the &lt;a href=&quot;http://www.geocaching.com/geocache/GC2R1D0_je-vous-recois-5-sur-5-i-read-you-loud-and-clear&quot; rel=&quot;nofollow&quot;&gt;link to the geo-cache&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3496" LastEditorUserId="19" LastEditDate="2016-07-04T15:28:22.793" LastActivityDate="2018-11-12T09:03:15.157" Title="How do you calculate the maximum distance to communicate with tower control?" Tags="&lt;radio-communications&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8581" PostTypeId="2" ParentId="8577" CreationDate="2014-09-13T20:14:04.543" Score="0" Body="&lt;p&gt;Your instinctive actions are correct; killing the engine &lt;strong&gt;&lt;em&gt;is the correct way&lt;/em&gt;&lt;/strong&gt; to handle this emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's part of the (generalized) procedure for landing a propeller aircraft with the gear up:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Pull the circuit breaker to the gear. We don't need the gear suddenly popping down and surprise us. Once you've made up the mind that the gear won't go down, stick to that decision.&lt;/li&gt;&#xA;&lt;li&gt;On short final, door latch open. The last thing you want is trapped in a smoking or burning aircraft.&lt;/li&gt;&#xA;&lt;li&gt;On crossing runway threshold, mixture cutoff, ignitions off, &lt;strong&gt;&lt;em&gt;master switch off&lt;/em&gt;&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;Flare as much as possible and aim to hit the ground at a slower speed&lt;/li&gt;&#xA;&lt;li&gt;Expect smoke to fill the cabin due to heat caused by friction, or even a fire&lt;/li&gt;&#xA;&lt;li&gt;If you have access to a fire extinguisher &lt;em&gt;while inside&lt;/em&gt;, extinguish cabin fires &lt;em&gt;only if absolutely necessary&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Get out of the aircraft ASAP.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Unless the aircraft has props hoisted on high wings, it's almost certain that the prop will hit the ground and smash. Even if the prop is not rotating as it hits the ground, it'll still be chopped off. The reason to turn everything off is to &lt;strong&gt;&lt;em&gt;minimize potential sparks, fire and explosion as much as possible&lt;/em&gt;&lt;/strong&gt;. Also expect extensive damage to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you'd want pretty little red lights standing by as you make the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for other comments saying you should not turn off the engine, obviously no sane pilot will do this while at 5000ft and 13mn from the airport, right?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-09-13T20:14:04.543" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8582" PostTypeId="2" ParentId="8565" CreationDate="2014-09-13T20:46:40.087" Score="15" Body="&lt;p&gt;Been there, done that. &lt;a href=&quot;http://www.airships.net/us-navy-rigid-airships/uss-akron-macon&quot; rel=&quot;nofollow noreferrer&quot;&gt;USS Akron and USS Macon&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sdJC0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airship would build up speed to somewhere around 40 miles per hour,    which was just about the stall speed of the F9C-2, and the Sparrowhawk would slowly and carefully maneuver into a position that allowed them to hook up to the same bar that hoisted them out.  Once hooked, the aircraft was hoisted inside of the airship, into its hanger [sic] bay, where a total of four aircraft could be stowed, with one ready to go on the hook/bar, for a total of 5 aircraft. -&lt;a href=&quot;http://www.farmboyzimsflightsims.com/FFF_CurtissSparrowhawk.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;farmboyzimsflightsims.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Having the momentum of the carrier ship, dropping into a 40+ mph head wind means you immediately gain lift and are essentially already 'flying'. Dropping from a head-windless stationary object... not so much.&lt;/p&gt;&#xA;" OwnerUserId="3497" LastEditorUserId="609" LastEditDate="2015-04-09T14:56:32.573" LastActivityDate="2015-04-09T14:56:32.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8583" PostTypeId="2" ParentId="8580" CreationDate="2014-09-13T21:04:23.940" Score="6" Body="&lt;p&gt;The formula for VHF range taught in flight schools&lt;sup&gt;1&lt;/sup&gt; is &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ d = 1.25 * \sqrt{h} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where d is the range in nautical miles and h is the height in feet of the receiver above the transmitter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in your case it would be (spoiler: mouse-over to see hidden text):&lt;/p&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; $$ 1.25 * \sqrt{(1981 - 335) * 3} \approx 87.84  $$&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, keep in mind that in some countries the range of Tower VHF radio tranmitters is limited so they only achieve a certain range. Uncontrolled airfields in Germany usually have a range of 30nm, which is achieved by limiting their power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1: &quot;Motorflug kompakt&quot; - Winfried Kassera / 2012 - p. 296&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="556" LastEditDate="2014-09-14T06:55:20.617" LastActivityDate="2014-09-14T06:55:20.617" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8584" PostTypeId="1" CreationDate="2014-09-14T03:18:53.163" Score="8" ViewCount="748" Body="&lt;p&gt;Some friends and I are going to fly up to Vegas from college to watch the Red Bull air races in a few weeks.  And after looking at the charts, I realized I am in a pretty unique situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Phoenix sectional ends just short of Vegas - so normally I would buy a Vegas sectional.  However, the KLAS TAC extends just into the Phoenix sectional.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should I buy the Vegas sectional as well, or can I just use the KLAS TAC once the Phoenix sectional ends?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NVs79.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="19" LastEditDate="2017-05-05T09:06:11.410" LastActivityDate="2017-05-05T14:26:25.560" Title="What charts do I need flying VFR between KPRC and KLAS?" Tags="&lt;usa&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8585" PostTypeId="2" ParentId="3413" CreationDate="2014-09-14T03:48:37.170" Score="3" Body="&lt;p&gt;The other problem with water contamination is that it can freeze in the fuel lines at high altitude, effectively blocking the fuel line with ice, and preventing the fuel getting through. Fuel treatments such as Liquid Engineering Fuel Set are recommended for preventing water from settling in fuel storage tanks, but not for aviation. This is because the water will still be present in minute particle size,- suspended in the fuel , and burnt in the fuel. But the tiny particles of water can still ice up at sub zero temperature.&lt;/p&gt;&#xA;" OwnerUserId="3500" LastActivityDate="2014-09-14T03:48:37.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8587" PostTypeId="2" ParentId="2170" CreationDate="2014-09-14T14:41:19.807" Score="3" Body="&lt;p&gt;A flat spin is a spin where, &lt;strong&gt;the aircraft is in a balanced state&lt;/strong&gt;. It just spins round and around like a spinning top. It won't recover because the forces acting on the airplane are in equilibrium. Controls and engine power become completely ineffective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can it happen? Yes, depending on the airplane design and center of gravity. If CG is aft it's more likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to avoid? &lt;strong&gt;To spin, you must first stall&lt;/strong&gt;. Avoiding stalls and proper stall recovery procedures are ways to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instructor, who was a military pilot, told us that one F-16 pilot entered a flat spin when he was playing around. He did not want to eject as the tapes would show that he lost a completely good aircraft on his own, not due to failures or accidents. He climbed out of the cockpit towards the nose. This upset the balance and tipped the nose down. He then climbed back and recovered the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-09-14T14:41:19.807" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8588" PostTypeId="2" ParentId="8584" CreationDate="2014-09-14T18:22:52.113" Score="9" Body="&lt;p&gt;If I understand correctly, your question is &quot;can I substitute a TAC for a sectional on a cross-country flight?&quot; However, assuming that you're flying under part 91, there is no legal requirement to have any charts on board at all. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1503&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.503&lt;/a&gt; does require them, but only for large and turbine aircraft, and the FAA &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/EB15B0C685650A0486257321006B3B8C?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;has stated&lt;/a&gt; that electronic charts are allowed instead of paper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few places where it is required to carry a chart in the aircraft, per the Special Flight Rules Area regulations in &lt;a href=&quot;https://www.ecfr.gov/cgi-bin/text-idx?SID=db6d462234c1e54c0fb044504e28fc56&amp;amp;mc=true&amp;amp;node=pt14.2.93&amp;amp;rgn=div5&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 93&lt;/a&gt;. Some examples are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Near Los Angeles International Airport (&lt;a href=&quot;https://www.ecfr.gov/cgi-bin/text-idx?SID=db6d462234c1e54c0fb044504e28fc56&amp;amp;mc=true&amp;amp;node=pt14.2.93&amp;amp;rgn=div5#se14.2.93_195&quot; rel=&quot;nofollow noreferrer&quot;&gt;93.95(c)&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;The Hudson and East River Exclusions in New York City (&lt;a href=&quot;https://www.ecfr.gov/cgi-bin/text-idx?SID=db6d462234c1e54c0fb044504e28fc56&amp;amp;mc=true&amp;amp;node=pt14.2.93&amp;amp;rgn=div5#se14.2.93_1351&quot; rel=&quot;nofollow noreferrer&quot;&gt;93.351(d)&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So unless 91.503 or one of the part 93 rules applies to your flight, legally you can carry whatever paper, electronic or hand-drawn charts you like - or none at all - although if you bust restricted airspace and the FAA come after you, not having charts on board may not look good. (Of course, if you do have them then the implication would be that you didn't use them or don't know how to read them, which isn't good either.)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-05-05T14:26:25.560" LastActivityDate="2017-05-05T14:26:25.560" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8590" PostTypeId="2" ParentId="2170" CreationDate="2014-09-14T19:33:41.593" Score="36" Body="&lt;p&gt;The F-14 is special; to stop the flat spin you need to &lt;strong&gt;pull&lt;/strong&gt; on the stick. Then the spin can be recovered from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is different from what you learn about regular spins, where &lt;strong&gt;pushing&lt;/strong&gt; the stick would be a better recovery method. In a flat spin, the forward fuselage dominates the aerodynamic forces, and we all know there are no control surfaces which could influence this flow. Wings and horizontal surfaces are fully separated, and elevator deflection is mostly useless. As others have pointed out before, a flat spin can only be stopped by shifting the center of gravity forward or deploying a &lt;a href=&quot;https://aviation.stackexchange.com/questions/26648/what-is-this-red-canister-on-the-tail-of-the-yf-22/26652#26652&quot;&gt;spin chute&lt;/a&gt;. The F-14 was an exception.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Spinning the F-14&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Early on, the Navy lost several F-14s due to flat spins. They then studied the phenomenon at &lt;a href=&quot;http://www.cnic.navy.mil/regions/ndw/installations/nas_patuxent_river.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pax River&lt;/a&gt;, and in the end &lt;a href=&quot;http://www.bihrle.com/company_info.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bill Bihrle&lt;/a&gt; found out that the elevator shields airflow from the two vertical tails of the F-14 when the stick is pushed, but moves out of the way when the stick is pulled full aft. You have to know that the elevator of the F-14 is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/16379/why-most-of-the-supersonic-or-fighter-aircraft-use-all-moving-control-surfaces&quot;&gt;full-flying surface&lt;/a&gt;, and the movement range is from -20° to +70°. At +70° it is almost in line with the airflow in a flat spin, and now the vertical tails are no longer in the wake of the elevator. They now can reduce the high yaw rate, which in turn reduces the high pitch-up moment of the rotating fuselage. With the lower inertial pitch-up moment, the elevator then has to be moved back to neutral, and the drag from wing and elevator is enough to pitch the aircraft fully down and out of the spin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Naturally stable &lt;a href=&quot;https://aviation.stackexchange.com/questions/2252/how-does-a-flying-wing-keep-from-going-into-a-flat-spin-when-maneuvering/3488#3488&quot;&gt;flying wings&lt;/a&gt; never enter a flat spin; their spin modes are all fairly steep due to the lack of a strong inertial moment from the lengthwise distribution of masses.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Influence of mass distribution&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I guess I now need to explain the inertial moment which causes the high pitch attitude in some aircraft. The axis of the spin rotation is close to the aircraft's nose, and the tail has the biggest distance from this axis. In a flat spin the axis of rotation is even more back, close to the center of gravity. All parts of the aircraft rotate with the same yaw rate, and the centrifugal force from this yawing motion grows linearly with distance from the spin axis. This difference in centrifugal force along the lengthwise coordinate of the aircraft pulls the aircraft in a near-horizontal attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Watch &lt;a href=&quot;https://www.youtube.com/watch?v=V2QiKjuoQLE&quot; rel=&quot;nofollow noreferrer&quot;&gt;this movie&lt;/a&gt; of the spinning XB-70 to get an idea how it looks. Depending on elevon settings, the spin axis is somewhere between the cockpit and the forward tip of the wing triangle. &lt;a href=&quot;https://www.youtube.com/watch?v=pbgtVPI-OOM&quot; rel=&quot;nofollow noreferrer&quot;&gt;With the damaged configuration&lt;/a&gt; (watch without sound for no distraction) you get a typical flat spin with the spin axis close to the center of gravity since there are few suction forces acting on most surfaces - only drag and the nose vortex (more on that below) remain.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;How to avoid flat spins&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If you have a configuration which is prone to flat spins, you need to change the shape of the fuselage tip. A rotating fuselage tip at high angle of attack will produce vortices at its side, and the yawing moment of these vortices will grow stronger with increasing yawing motion. This is why a flat spin is self-stabilizing. One way to suppress these vortices is the placement of small spoiler strips along the nose (which fixes the vortex position and reduces this self-stabilizing effect), and another is to make the nose shape flatter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, this can only be done long before take-off.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Answer to your question&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Regarding the &quot;Top Gun&quot; scenario: If the F-14 is at high angle of attack and the jet wash hits it asymmetrically, the airplane could enter into a spin. But from there it is still some way to the fully developed flat spin, and I would expect that a skilled pilot could recover from this momentary upset.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-11-21T07:11:02.103" LastActivityDate="2019-11-21T07:11:02.103" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="8591" PostTypeId="2" ParentId="8577" CreationDate="2014-09-15T13:00:24.463" Score="9" Body="&lt;p&gt;Don't shut down your engine, it's a bad idea. Your aircraft will require substantial repairs in any case, the most important thing is to land safely. Loss of engine power is a serious emergency, worse than landing gear not lowering, cutting your engine is multiplying the risk several times over. Survival in this case depends on a smooth, controlled landing; cutting the engine causes risks to this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Higher descent rate: most aircraft have a higher descent rate without engine power than at idle, sometimes this is substantial. A higher descent rate is not good when the smoothness of your landing is critical&lt;/li&gt;&#xA;&lt;li&gt;No control over descent rate: without your engine you cannot add a burst of power to smooth out a sudden drop. This could lead to you slamming down on your belly instead of having a controlled landing. It could also lead to landing short of the runway if you cut it too soon. This has happened several times, and often is not survivable&lt;/li&gt;&#xA;&lt;li&gt;Inexperience with dead stick landings: Few people have ever experienced how an aircraft without power handles and lands, you'll be entering new territory for which you've had no training&lt;/li&gt;&#xA;&lt;li&gt;Less control without the engine: Airflow (at least in single engines) contributes to elevator and rudder authority, even when at idle, you need all the authority you can get for the most controlled landing possible. Also, you can use your prop to keep you in place in a crosswind&lt;/li&gt;&#xA;&lt;li&gt;No option to go around: once you cut your engine you are committed and have no option but to land, what if a big gust blasts you off centerline and into the path of a hangar? Or what if you aren't perfect and want to have another try? &lt;/li&gt;&#xA;&lt;li&gt;Change of attitude and balance: Cutting the engine will give some pitch down on most aircraft which would need to be controlled for, but you've cut your master switch so your electric trim is out - better start winding that lever or have the arms of a gorilla&lt;/li&gt;&#xA;&lt;li&gt;Distraction at a critical time: Landing is one of the busiest times in an aircraft, you have to watch your airspeed, descent rate, and if it's bumpy you'll be sawing away at the controls. Having to pull the mixture - bump the prop to it's horizontal (no point cutting the engine otherwise) - cut the mags - fuel stopcock off - master switch off all while arresting an increased sink rate, trimming, and coming to terms with all the balance changes will all add massively to your workload when you most need to be concentrating on making a controlled, gentle descent. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;A good landing comes from a good approach, cutting your engine throws that away, and you cannot go around if you hose it up or conditions aren't right. Instead make a controlled approach, brief your passengers on emergency procedures, tell them to brace. When your airplane comes into contact with the ground use whatever control authority you have to keep it controlled, then once it is slowed cut your fuel, mags, etc. As Bob Hoover said &quot;fly it as far into the accident as possible.&quot; &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-09-15T13:00:24.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8592" PostTypeId="1" AcceptedAnswerId="8596" CreationDate="2014-09-15T14:17:04.403" Score="9" ViewCount="4501" Body="&lt;p&gt;A short-haul flight does not spend much time in its cruise level (let's say less than two hours). Thus, it is important to rapidly reach the optimal flight level and I think this kind of aircraft should be optimised to climb. On the opposite, on long-haul flights there the climb and descent reprsent a tiny portion of the whole flight. The aircraft should then be optimised to consume as little fuel as possible during cruise, even if climb rate is less important. That's why I wonder if my thinking is right and if there are significant differences in climb rate between short and long-haul aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related thinking: On average, does a short-haul flight descent more rapidly than a long-haul? I think not as this diving has no reason to be related to climb/cruise performance and all commercial aircraft are made to use the same airports with the same approach pattern; but that's only an assumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: OK, the quantity of fuel is quite important. I suppose an aircraft designed to be heavier (long-haul, carrying lots of fuel and payload) is equipped with more powerful engines and thus if it is lighter than designed for (lets say a B777 or a A330 used on short-haul flights), it climbs faster than the same aircraft in a long-haul flight. But the long-haul aircraft is designed to make long-haul flights. Maybe I should have asked if there is a significant difference in climb rate between short and long-haul aircraft at their maximum operating take-off weight.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1961" LastEditDate="2014-12-06T12:30:28.593" LastActivityDate="2017-02-12T11:56:29.297" Title="Is the climb rate different for short-haul flight and long-haul flight?" Tags="&lt;commercial-aviation&gt;&lt;takeoff&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8593" PostTypeId="2" ParentId="8592" CreationDate="2014-09-15T15:12:16.893" Score="2" Body="&lt;p&gt;Short answer: yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: on a long haul aircraft, it carries a lot of fuel for the next 12 hours. That extra weight has quite an impact on climb performance. E.g. it takes more time for a fully loaded B777 to climb to 10000 feet, compared to a B777 configured for short haul. (Yes, many Asian airlines use B777 for short haul trips. The shortest one I can think of is CX flying Hong Kong to Taipei, a trip less than 2 hours)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long haul flights also just cannot climb that high. The pilots can crank the engines max and it'll just go perhaps FL270 - FL300. Once after few hours, they burn up some fuel than climb, up to FL390 or higher. These are called &lt;em&gt;step climbs&lt;/em&gt; : burn some gas, climb a bit, burn some more gas, climb again, and so on.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-09-15T15:12:16.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8594" PostTypeId="2" ParentId="8592" CreationDate="2014-09-15T16:43:34.657" Score="3" Body="&lt;p&gt;No, not for the reasons you ask about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Absent restrictions due to other traffic, terrain or weather, pilots will always choose to maintain the best rate of climb speed ($v_y$, a.k.a. &quot;green dot speed&quot;) and run the engines at the recommended climb power, simply because that's when the plane flies most efficiently. The actual performance differs due to weight and weather, but that is not directly related to length of the flight leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly the descent is again flown in a way that makes it most efficient (I believe that means close to maximum rate without speed brakes), which is again not directly related to length of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What short flights do is stop the climb at lower altitude (than permitted by load), because the time spent on higher level would be too short for the lower fuel consumption to offset the additional fuel needed to get there.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-15T16:43:34.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8595" PostTypeId="2" ParentId="8556" CreationDate="2014-09-15T16:59:50.127" Score="12" Body="&lt;p&gt;In addition to the principles and research of other answers, here is a look at the winglet design chosen on different aircraft. Is a winglet always preferred, or only in certain circumstances?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/8554/1696&quot;&gt;this answer&lt;/a&gt;, it is mentioned that it can make sense to add a winglet when span is restricted. Therefore, it is important to understand reasons why span may be restricted on an airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wingspan is limited structurally because bending moments place increased stress on the wing structure as the distance from the wing root increases. This means increased material and weight to handle the stress, which reduces some of the benefits of the increased span. These limits will depend on the wing structure, which varies between aircraft, so they will not be focused on here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wingspan is also limited by regulations. In &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5300_13A.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5300-13A&lt;/a&gt; by the FAA, on page 13, Table 1-2 lists six Airplane Design Groups into which aircraft are categorized based on tail height and wingspan. ICAO Annex 14 has these same groups but labeled A-F. Aside from clearance at gates and on taxiways, the group also affects other airport facilities. In most cases the wingspan is more critical than the tail height, so wingspan will be focused on here.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Group #     Wingspan (ft)&#xA;I           &amp;lt;49&#xA;II          49-&amp;lt;79&#xA;III         79-&amp;lt;118&#xA;IV          118-&amp;lt;171&#xA;V           171-&amp;lt;214&#xA;VI          214-&amp;lt;262&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Below are different aircraft, and the groups in which the wingspan is categorized (values from Wikipedia). Lengths are rounded down to the nearest foot to compare against the limits. This focuses on aircraft that come with winglets as designed. Winglets available as retrofits improve performance, but the question is whether a wingspan extension would be better, which will depend on each aircraft's design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will see that aircraft at the upper limit of wingspan in a certain group tend to have winglets, whereas aircraft not at the limit do not. There are some exceptions to this. The LR/ER versions of the 777 reached the wingspan limit of Group V, but opted for raked tips instead of winglets. The A330/340 are below the limit of Group V but use winglets, though newer versions of the A340 do reach the limit, and all are at the upper end of the group.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An interesting case is the P-8, which is an ASW aircraft based on the 737-800. The military is less concerned with wingspan classes than commercial carriers, and endurance is an important design goal for this role. The design opted to increase wingspan and use raked tips rather than retain or add the winglets of the 737-800.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this it seems that winglets are more useful when at a limit in wingspan. It suggests that winglets are less useful when not limited in wingspan, but is certainly not conclusive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A380-800&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 261 ft (Group VI)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B777-8X/9X&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 235 ft (Group VI), fold to 212 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B747-8&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 224 ft (Group VI)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A350&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 213 ft (Group V)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B777-200LR/300ER&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 212 feet (Group V)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B747-400&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 211 ft (Group V)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A340-500/600&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 208 ft (Group V)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B777&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 199 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B787-8/9/10&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 197 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A340-200/300&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 197 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A330&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 197 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P-8 (Based on 737-800)&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 123 ft (Group IV)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A320/neo&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 111 ft (117 ft with sharklets) (Group III)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B737 NG/MAX&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 117 ft (with winglets) (Group III)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B737 Classic&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 94 ft (Group III)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;E170/175/190/195&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 85 ft (E170/175) 94 ft (E190/195) (Group III)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Less common aircraft:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SSJ 100&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 91 ft (Group III)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: no&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;IL96&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 197 ft (Group V)&lt;br&gt;&#xA;Group Max: no&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CS100/300&lt;/strong&gt;&lt;br&gt;&#xA;Wingspan: 115 ft (Group III)&lt;br&gt;&#xA;Group Max: yes&lt;br&gt;&#xA;Winglets: yes&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-09-15T16:59:50.127" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8596" PostTypeId="2" ParentId="8592" CreationDate="2014-09-15T19:32:27.137" Score="6" Body="&lt;p&gt;Different climb performance is indeed indirectly linked to the length of the trip, but this has to do with the number of engines. All airliner's engines are sized to support flying with an engine failure right after take-off. Twin-engined aircraft enjoy slightly less stringent rules, but will basically carry twice the thrust that they need to stay aloft, so more excess power is available than in four-engined aircraft, which have only 33% excess thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the best performance is achieved when running the engines at their maximum continuous thrust setting and when climbing as fast as possible. That is the reason why an A-320 or a Boeing 737 will climb faster than an Airbus A-340 or a Boeing 747. On descent, the number of engines is less relevant, so the descent speeds of all types are similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The link between engine numbers and range was strongest in the early jet age; now it is less clear-cut with long-range airplanes like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777#777-200LR&quot; rel=&quot;nofollow&quot;&gt;Boeing 777-200 LR&lt;/a&gt; or short-range airplanes like the &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Aerospace_146&quot; rel=&quot;nofollow&quot;&gt;BAe 146&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-06T12:23:15.300" LastActivityDate="2014-12-06T12:23:15.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8597" PostTypeId="1" CreationDate="2014-09-16T05:05:41.287" Score="6" ViewCount="745" Body="&lt;p&gt;A few days ago, &lt;a href=&quot;http://reason.com/blog/2014/09/15/tsa-demand-to-search-man-after-plane-lan&quot;&gt;Kahler Nygard&lt;/a&gt; reportedly received a boarding pass indicating &lt;a href=&quot;http://en.wikipedia.org/wiki/Secondary_Security_Screening_Selection&quot;&gt;secondary screening&lt;/a&gt; was required, but that pat-down was reportedly never done. So when the plane landed, they took the passenger off the plane ahead of the others and requested that he submit to the screening at the destination airport, after the flight. He recorded the incident on his phone, and after confirming that he wasn't being detained, simply walked away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The proposition that screening a passenger &lt;em&gt;after&lt;/em&gt; the flight has landed might retroactively increase the fight's safety is, I think we can all agree, counter to the fundamental nature of causality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the question is this: &lt;strong&gt;Is screening passengers after they have arrived at their destination without incident within the rights and responsibilities of the TSA?&lt;/strong&gt; Clearly it doesn't jive with the whole &quot;cause and effect&quot; framework of reality that we all live in, but are they within their rights to demand such screening anyway?&lt;/p&gt;&#xA;" OwnerUserId="2426" LastActivityDate="2014-09-17T11:02:24.093" Title="Can the TSA require supplemental screening AFTER a flight has landed?" Tags="&lt;commercial-aviation&gt;&lt;security&gt;&lt;tsa&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2014-09-17T14:59:54.683" ContentLicense="CC BY-SA 3.0" />
  <row Id="8598" PostTypeId="1" AcceptedAnswerId="8824" CreationDate="2014-09-16T12:59:16.517" Score="13" ViewCount="1174" Body="&lt;p&gt;I was looking at a video of a A380 display that led me to the &quot;valse des ailerons&quot;. This strange ailerons behaviour is available in normal law, but what happen when some fly-by-wire features are not available (alternate law and direct law)? Is this kinematic still available or do all the aileron move together acting as if there was only one aileron per wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: As I received no responses but multiple good comments, I add some clarifications:&#xA;The &quot;Valse des ailerons&quot;' purpose and operating is documented in many places (see comments) but all those documentations assume the fly-by-wire system (sensors, actuators, computers,...) is healthy enough to stay in normal law. My question is: what happen when in alternate or direct law? Is there multiple cases, some in which the valse des ailerons is still available and some in which it is not?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2014-09-24T14:55:52.257" LastActivityDate="2017-07-30T17:53:30.693" Title="Is the A380 ailerons' kinematic modified in alternate law?" Tags="&lt;ailerons&gt;&lt;airbus-a380&gt;&lt;fly-by-wire&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8599" PostTypeId="1" AcceptedAnswerId="8601" CreationDate="2014-09-16T17:36:41.303" Score="9" ViewCount="809" Body="&lt;p&gt;Aircraft with variable pitch propellers usually have a red arc on the propeller speed gauge somewhere between about 500 and 1000 rpm, often accompanied by placard like &quot;stabilized propeller operation between 500 rpm and 1000 rpm is prohibited&quot; (the range is slightly different in different aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this restriction?&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-19T17:33:29.323" Title="Why shouldn't variable pitch propellers be operated at low speed?" Tags="&lt;constant-speed-propeller&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8600" PostTypeId="1" AcceptedAnswerId="8627" CreationDate="2014-09-16T17:51:37.613" Score="5" ViewCount="1069" Body="&lt;p&gt;The 1090 ES is the transponder system used in ADS-B.&#xA;Why does the 1090 ES use the same frequency (1090MHz) for uplink as well as downlink? 1090 ES is an extension of Mode S. The Mode S used 1030MHz for uplink and 1090MHz for downlink. Why did the 1090 ES change that? Having two frequency channels would be better (More space less noise due to message collisions) for communication right?&lt;/p&gt;&#xA;" OwnerUserId="3491" LastEditorUserId="64" LastEditDate="2014-09-16T18:20:02.997" LastActivityDate="2014-09-18T17:31:24.653" Title="Why does the 1090 ES use the same frequency for both uplink and downlink?" Tags="&lt;ads-b&gt;&lt;transponder&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8601" PostTypeId="2" ParentId="8599" CreationDate="2014-09-16T17:57:59.167" Score="7" Body="&lt;p&gt;The specific reasons may be specific to each propeller/engine combination, but in general it seems to be related to stresses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this &lt;a href=&quot;http://www.enhanced.aero/pdf/performance_raisbeck.pdf&quot; rel=&quot;nofollow&quot;&gt;King Air POH&lt;/a&gt; on page 2-2:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Stabilized ground operation between 400 and 1,150 propeller RPM is prohibited. Operation between 0 and 400 propeller RPM is permissible only with propeller feathered.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;STABILIZED GROUND OPERATION WITHIN THE PROPELLER RESTRICTED RPM RANGE CAN GENERATE HIGH PROPELLER STRESSES AND RESULT IN PROPELLER FAILURE AND LOSS OF CONTROL OF THE AIRCRAFT.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is probably due to the frequency of the aerodynamic forces at those RPM's resonating with the frequency of the propeller, and getting amplified to unsafe stress levels. This is called ground resonance and is also an issue with helicopters. In addition to over-stressing the propeller blades, it can also affect the fatigue life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a discussion in &lt;a href=&quot;http://www.vansairforce.com/community/showthread.php?t=217&quot; rel=&quot;nofollow&quot;&gt;this thread&lt;/a&gt;, and it is mentioned in &lt;a href=&quot;http://t6gouge.com/pdf/T-6%20KNOW%20IT%20ALL.pdf&quot; rel=&quot;nofollow&quot;&gt;this guide&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As voretaq7 mentions, fixed-pitch propellers have similar restrictions for similar reasons. Some engines include a damper that removes this restriction by damping out the resonance.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-19T17:33:29.323" LastActivityDate="2014-09-19T17:33:29.323" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8602" PostTypeId="1" AcceptedAnswerId="8604" CreationDate="2014-09-16T18:00:28.413" Score="27" ViewCount="44247" Body="&lt;p&gt;What would happen if a plane (for the sake of the question let's say that the plane is an Airbus A380) lose its  Vertical Stabilizer?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yP7rR.png&quot; alt=&quot;Vertical Stabilizer&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1700" LastActivityDate="2020-06-09T08:39:43.177" Title="Can a plane fly without the Vertical Stabilizer?" Tags="&lt;aircraft-design&gt;&lt;emergency&gt;&lt;airbus-a380&gt;" AnswerCount="10" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8603" PostTypeId="2" ParentId="8602" CreationDate="2014-09-16T18:06:59.703" Score="17" Body="&lt;p&gt;There are several planes that are designed to fly without vertical stabilizers (like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot; rel=&quot;noreferrer&quot;&gt;B-2 bomber&lt;/a&gt;, for example).  But they have very clever split flaps that make up for the lack of stability/control usually provided by a horizontal stabilizer/rudder setup.  Basically a split flap will open up and create more drag on the wing the aileron is placed on, pulling that side of the aircraft back.  Thus those aircraft use that system for horizontal stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane is not designed to work without the verticle stabilizer, it would have problems if it lost it.  On craft with horizontal stabilizers, in general, if the plane gets a little bit sideways the airflow will push against the stabilizer and thus move the plane back in line.  If you lost that system, you'd have the find another way to compensate for yaw instability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is theoretically possible that you could use differential thrust between the engines to keep the plane in line.  Granted, the response would be very sluggish and difficult to control (especially on a big jet like the A380), but it's possible that it could be done given the right plane (one with quickly responding engines) and the right conditions (smooth air, basically).&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2014-09-19T15:23:30.777" LastActivityDate="2014-09-19T15:23:30.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8604" PostTypeId="2" ParentId="8602" CreationDate="2014-09-16T18:18:17.313" Score="39" Body="&lt;p&gt;The plane will probably crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vertical stabilizer provides stability in yaw to conventional aircraft. Aircraft such as the B-2 manage to provide stability through computer control, and aircraft such as the Northrop flying wings are designed to fly without one. But if an aircraft designed to be stable using a vertical stabilizer loses that surface, it will be very difficult for pilots to stabilize manually with the remaining systems. While roll and differential thrust will both affect yaw, they will both be slower to react than a rudder, especially in a large aircraft like an A380. This can also damage the hydraulic systems, making it more difficult to control the remaining surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If experienced test pilots are at the controls (as in the B-52 incident below), or if the failure is anticipated and trained for, it's possible that the aircraft would be controllable enough to land safely. However, as the incidents below show, this kind of failure does not happen often, and can easily exceed the crew's ability to control the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples where this has happened:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot;&gt;Japan Airlines Flight 123&lt;/a&gt; lost most of its vertical stabilizer when the rear pressure bulkhead failed. Despite also losing hydraulic systems, the pilots managed to keep the plane in the air for a while, but ended up crashing into a mountain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot;&gt;American Airlines Flight 587&lt;/a&gt; lost its vertical stabilizer when the pilot's rudder inputs over-stressed the structure. It crashed shortly after.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1964, a B-52 &lt;a href=&quot;http://www.talkingproud.us/Military/B52%20No%20Tail/B52NoTail.html&quot;&gt;lost most of its vertical stabilizer&lt;/a&gt; due to extreme turbulence. The pilots were able to extend air brakes on the wing tips to provide some stability. The Air Force sent up a chase plane to help guide the pilots, and provided engineering guidance from the ground. The crew were able to bring the plane back for a safe landing (&lt;a href=&quot;https://www.youtube.com/watch?v=WJuEAQbxWRo&quot;&gt;see a video&lt;/a&gt;). There were at least &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_aircraft_structural_failures&quot;&gt;three other instances&lt;/a&gt; where the vertical stabilizer failed on B-52's, all ending with the loss of the plane. This particular flight was conducted with test pilots to intentionally fly through turbulence, recording data to help understand the failures on the other aircraft. However, the flight encountered unexpectedly severe turbulence, leading to the separation of the vertical stabilizer.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-17T14:43:29.010" LastActivityDate="2014-09-17T14:43:29.010" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8605" PostTypeId="2" ParentId="8602" CreationDate="2014-09-16T18:19:34.567" Score="15" Body="&lt;p&gt;Probably not. One sad example is &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot;&gt;American Airlines Flight 587&lt;/a&gt;.&#xA;If the plane loses just a small part of of the fin, it might be ok, but if it loses the fin completely two major things happen:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The plane becomes unstable in yaw. If the plane needed such a big surface behind its center of gravity (CG) to be stable there is almost no chance of flying without it.&lt;/li&gt;&#xA;&lt;li&gt;There is a significant mass loss at a big distance from the CG. This will lead to a sudden shift of the CG towards the front of the plane which will make the plane dive, possibly beyond any chance of recovery.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Aggravating to the above is the fact that most likely the pilots wouldn't be aware of what actually happened and it would be very difficult for them to take proper action. &lt;/p&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="3488" LastEditDate="2014-09-18T09:07:56.890" LastActivityDate="2014-09-18T09:07:56.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8606" PostTypeId="2" ParentId="8602" CreationDate="2014-09-16T19:48:01.880" Score="27" Body="&lt;p&gt;As always, it depends. There are several things which provide directional stability:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The stabilizer, obviously,&lt;/li&gt;&#xA;&lt;li&gt;Positive wing sweep,&lt;/li&gt;&#xA;&lt;li&gt;Fins and&lt;/li&gt;&#xA;&lt;li&gt;pusher propellers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;They have to work against the destabilizing parts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The fuselage,&lt;/li&gt;&#xA;&lt;li&gt;External tanks and stores,&lt;/li&gt;&#xA;&lt;li&gt;Tractor propellers and&lt;/li&gt;&#xA;&lt;li&gt;Forward-facing engine nacelles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the vertical is the only stabilizing part, losing it means to crash shortly after. Airplanes need to face forward to create sufficient lift. Momentary exceptions don't count: WW I fighter airplanes had very small vertical tails, and consequently low directional stability. Several German pilots of WW I perfected a technique where sudden rudder input would push the airplane beyond the stable regime of yaw angles, and the airplane would make a quick, full rotation around its vertical axis. This would scare the pilots of pursuing airplanes, because now the machine guns of their adversary would point at them. But there was no real possibility to aim, and the rotation speed was so high that very few shots would actually go in the direction of the pursuing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The size of the vertical tail of multi-engined aircraft is driven by the need to counteract the yawing moment due to a failed engine. If all engines are running, the vertical tail needs only to be 1/3 as big. If low &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;noreferrer&quot;&gt;dutch roll&lt;/a&gt; stability is tolerated, it could be cut back even more. Therefore, if the other parts can contribute enough stability, a partial loss of the vertical surface can be survived. With a swept wing, the key is to fly in a flight regime where it helps the most, that is at low speed. In the case of the B-52H 61-023, which had this happen to it on January 10, 1964, additional help was provided by lowering the rear landing gear which contributed a small fin effect and by shifting the center of gravity forward by pumping fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8gmU1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if any more of the stabilizer had broken off, longitudinal stability would have been lost. Those guys were both lucky, and very skilled pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;61-023 was repaired and flew for more than 40 years after this incident. It was retired in 2008.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-18T21:48:20.080" LastActivityDate="2014-09-18T21:48:20.080" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8607" PostTypeId="2" ParentId="8600" CreationDate="2014-09-16T20:16:41.243" Score="5" Body="&lt;p&gt;It's a broadcast protocol - devices spontaneously announce themselves for listeners to hear. There are no interrogations to put on a different channel.&lt;/p&gt;&#xA;" OwnerUserId="938" LastActivityDate="2014-09-16T20:16:41.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8608" PostTypeId="1" CreationDate="2014-09-17T00:30:19.553" Score="10" ViewCount="1128" Body="&lt;p&gt;If there is a loss of/lack of air pressure at high altitude, without an explosive decompression (for instance as on &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot;&gt;Helios 522&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash&quot;&gt;N47BA&lt;/a&gt;) are there any signs that pilots can look out for that they might not be getting enough oxygen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does an audible alarm exist on any commercial jets when cabin pressure is at a dangerous level?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's my understanding that the brain is impaired, and reaction times are increased with oxygen deprivation. Are there any techniques to combat this, after noticing hypoxia onset? e.g. slowed breathing&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-09-17T00:37:26.227" LastActivityDate="2014-09-25T01:47:31.383" Title="What can pilots do to spot the onset of hypoxia?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;hypoxia&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8609" PostTypeId="2" ParentId="8608" CreationDate="2014-09-17T01:00:13.390" Score="7" Body="&lt;p&gt;A good amount of information can be found in the &lt;a href=&quot;http://www.skybrary.aero/index.php/Hypoxia_%28OGHFA_BN%29&quot;&gt;Operator's Guide to Human Factors in Aviation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hypoxia can be recognized from both objective (i.e., capable of being perceived by an observer) and subjective (i.e., perceived by the pilot only) symptoms. Objective signs include increased rate and depth of breathing, tachycardia, cyanosis (blue-colored lips and nails), mental confusion, anger, euphoria, poor judgment, loss of muscle coordination, slouching and loss of consciousness. Behavioral changes may be noted by the hypoxic individual, as well as by the observer. The subjective symptoms include breathlessness, apprehension, headache, dizziness, fatigue, nausea, hot and cold flashes, blurred vision, tunnel vision, tingling, and numbness.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The only way to reverse the effects of hypoxia is to provide the lungs with a greater partial pressure of oxygen. This can be done using either supplemental oxygen (mask), or descending to a lower altitude. Corrective action must be taken quickly, as any delay makes the effects of hypoxia worse.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-09-17T01:00:13.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8611" PostTypeId="2" ParentId="8608" CreationDate="2014-09-17T05:16:22.783" Score="8" Body="&lt;p&gt;Yes, all pressurized aircraft have cabin altitude (= altitude at which the same pressure as currently in the cabin normally occurs) indicator with alert when it exceeds safe value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Helios 522 that alarm did sound. The crew however mistook it for configuration alarm which only makes sense during take-off roll and thus considered it spurious. When the technician they called realized it was cabin altitude warning, the pilots were already too confused to carry out his orders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The symptoms are already listed in the other answer. The problem is that the initial symptoms feel just like fatigue. One starts to feel sleepy and at that moment one might not realize it could be due to hypoxia as mental capacity is already reduced.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-17T05:16:22.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8612" PostTypeId="2" ParentId="8602" CreationDate="2014-09-17T09:27:07.607" Score="3" Body="&lt;p&gt;I am pretty sure a plane that has fly by wire will not crash.  Fly by wire controls the stability of a plane by adjusting the control surfaces.  When the flaps are out it will balance both sides to prevent yaw.  I see no reason why the failure of the vertical stabilizer cannot be compensated by controlling the flaps.  A pilot couldn't do that.  A computer yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I am not so sure anymore.  Loosing the whole vertical stabilizer is much worse than loosing just the rudder.  But I would say there still is hope.&lt;/p&gt;&#xA;" OwnerUserId="3513" LastEditorUserId="3513" LastEditDate="2014-09-17T15:35:33.827" LastActivityDate="2014-09-17T15:35:33.827" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8613" PostTypeId="1" AcceptedAnswerId="8616" CreationDate="2014-09-17T09:55:51.693" Score="18" ViewCount="11605" Body="&lt;p&gt;A normal aircraft has multiple hydraulic circuit, identified by colors (e.g. according to the ATSB final report of the QF32 the green hydraulic line was disabled; according to the BEA final report of the AF4590 the Concorde had a yellow, a blue and a green circuit, ...). I understand the need to be equipped of several independant hydraulic system (redundancy) and the need of being able to identify those. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to the previous example, I figured out the hydraulic circuits are identify by colors. &#xA;Does it mean the hydraulic fluid is colored (useful in case of leak)? Does it means the elements of each circuit is painted accordingly (usefull for maintenance)? &lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2017-07-20T08:41:24.873" Title="Is the hydraulic fluid artificially colored?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8614" PostTypeId="2" ParentId="8613" CreationDate="2014-09-17T10:03:56.107" Score="13" Body="&lt;p&gt;It is just the components that will be labeled accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having each fluid be colored differently is a maintenance nightmare, you need to have all 3 colors available in the hangar and each system must be fully isolated (3 different pumps, buffers, actuators etc.) to avoid contamination.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-09-17T10:03:56.107" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8615" PostTypeId="2" ParentId="8597" CreationDate="2014-09-17T11:02:24.093" Score="3" Body="&lt;p&gt;TSA staff actually have very little authority - they can prevent you boarding an airplane, they can stop the airplane from leaving. For everything else, they call the local police (the phone is their Big Stick - they &lt;em&gt;can&lt;/em&gt; call in some serious assistance, like SWAT or some loaded F-22s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sounds like a classic bureaucratic whoopsie - someone missed the initial screening note, someone else noticed that the box wasn't ticked in the system, and protecting the monthly performance statistics prevailed over common sense. Since the passenger declined the search they can prevent said passenger from boarding a flight, but since he did not wish to board a flight (and has not done anything illegal) all they can do is ask him to leave the secure area. As that is exactly what the passenger wanted to do anyway.....&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-09-17T11:02:24.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8616" PostTypeId="2" ParentId="8613" CreationDate="2014-09-17T15:26:53.187" Score="20" Body="&lt;p&gt;A common hydraulic fluid used in aircraft is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Skydrol&quot; rel=&quot;noreferrer&quot;&gt;Skydrol&lt;/a&gt;. The fluid is artificially colored, but this does not depend on which circuit it is in. The &lt;a href=&quot;http://www.skydrol.com/pages/faqs.asp&quot; rel=&quot;noreferrer&quot;&gt;FAQ&lt;/a&gt; on the manufacturer's site addresses the color.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Skydrol fluids are given a &lt;strong&gt;purple dye&lt;/strong&gt; to make it easy to distinguish them from other fluids. But the dye does not usually last as long as the fluid does. &lt;strong&gt;The color may change from purple to gray or yellow or green,&lt;/strong&gt; yet the fluid can still meet all used fluid specifications. &lt;strong&gt;Color is not a reliable indicator of fluid quality&lt;/strong&gt;, and we recommend that the system be sampled for chemical analysis to determine if it is suitable for use. A dark amber color, however, is a cause for concern, and can indicate a severely stressed fluid. Call Solutia's Technical Service for assistance if you are unsure about a fluid's color. Our technical bulletin has a color chart to use as a guide.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Initially the color helps to distinguish from other fluids, and having multiple colors would make it more complicated. It notes that the color also does not remain constant, so even if it were colored initially, it would probably end up changing anyway. It also mentions that a dark amber color can be an indicator of issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find any good pictures, but the lines are probably not color coded. Any colored hydraulic system components are generally purple (like the fluid). The lines themselves &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook/media/FAA-8083-30_Ch07.pdf&quot; rel=&quot;noreferrer&quot;&gt;can be labeled&lt;/a&gt;, but the standard for hydraulic lines is &lt;a href=&quot;https://www.compaero.com/pdf/FLUID%20LINE.PDF&quot; rel=&quot;noreferrer&quot;&gt;blue and yellow&lt;/a&gt;. The end fittings are colored to identify the tube material type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maintenance manuals will show the layout and label the different lines. Also, on &lt;a href=&quot;http://asrs.arc.nasa.gov/publications/callback/cb_402.html&quot; rel=&quot;noreferrer&quot;&gt;this ASRS page&lt;/a&gt;, one report is from a mechanic that confused the green and yellow system fittings, which probably wouldn't have happened if they were color coded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1jRdC.jpg&quot; alt=&quot;Jar of Skydrol showing purple color&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-12-14T21:19:24.923" LastActivityDate="2015-12-14T21:19:24.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8617" PostTypeId="1" AcceptedAnswerId="8737" CreationDate="2014-09-17T20:17:03.433" Score="8" ViewCount="343" Body="&lt;p&gt;I'm from Brazil, and I am working on an IFR certification process via AATD Training Course. We are having problems with the flight instructors; they must have valid IFR and CFI licences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instructors are pilots with more than 10000 hrs, that have already flown heavy jets and executive jets.  Our national agency is not accepting our training program because they don't fly anymore and they don't have valid licences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to know how the certification process works in other countries, such as the US or in Europe.&lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="1696" LastEditDate="2015-04-22T17:29:42.417" LastActivityDate="2015-04-22T17:29:42.417" Title="What qualifications are required for an authorized flight instructor to teach IFR in AATD simulators, in the U.S.?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;instrument-flight-rules&gt;&lt;cfi&gt;&lt;aatd&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8619" PostTypeId="1" CreationDate="2014-09-17T21:14:02.147" Score="7" ViewCount="3024" Body="&lt;p&gt;I have several present weather symbols from the weather depiction chart that I'm not clear on and AC-0045 doesn't have in it's legend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the mist and fog symbols, and these look very similar, but I'm not sure what the broken lines imply.  I've added three variations on the symbol below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z3h0T.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8kucn.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/B8TmL.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3516" LastEditorUserId="97" LastEditDate="2015-05-03T00:54:06.000" LastActivityDate="2015-05-03T00:54:06.000" Title="What do these weather depiction chart symbols mean?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8621" PostTypeId="2" ParentId="8619" CreationDate="2014-09-17T21:41:09.053" Score="17" Body="&lt;p&gt;Since the other user posted a link that contained the answer that could in the future go 404, I'll provide the answer I found there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first symbol means &quot;Fog in patches&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second symbol is not present but by extrapolations likely means either &quot;Mist in patches&quot; or &quot;Mist with sky visible&quot;.  The former seems more likely to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The third symbol means &quot;Fog, sky visible.&quot;&lt;/p&gt;&#xA;" OwnerUserId="3516" LastActivityDate="2014-09-17T21:41:09.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8622" PostTypeId="2" ParentId="8602" CreationDate="2014-09-17T22:19:28.127" Score="3" Body="&lt;p&gt;Sure it will (aerodynamically speaking). As previously mentioned, it pretty much requires a digital flight control system though (aka 'fly by wire'). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_X-44_MANTA&quot; rel=&quot;nofollow&quot;&gt;Lockheed Martin X-44 Manta&lt;/a&gt; is pretty much the F-22 without vertical flight control surfaces.&lt;/p&gt;&#xA;" OwnerUserId="3517" LastEditorUserId="65" LastEditDate="2014-09-18T00:05:47.947" LastActivityDate="2014-09-18T00:05:47.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8623" PostTypeId="2" ParentId="3649" CreationDate="2014-09-18T07:11:05.057" Score="11" Body="&lt;p&gt;I didn't see specific distances mentioned for the second part of the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the runways (centerline to centerline) are separated by at least 4300 feet (and other conditions are met), the airport can conduct simultaneous instrument approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the runways are ate least 2500 feet apart, they can conduct staggered approaches (both runways in use, but aircraft do not approach alongside each other).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a reference, the SFO runways have a centerline separation of 750 feet.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From the AIM&#xA;&lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0504.html#?F8258ROBE&quot; rel=&quot;noreferrer&quot;&gt;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0504.html#?F8258ROBE&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cOfYc.gif&quot; alt=&quot;Runway separation diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also shows the situation that waivers are possible for separations less than 4300 feet if additional conditions are met.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="3159" LastEditDate="2014-09-18T08:28:08.190" LastActivityDate="2014-09-18T08:28:08.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8627" PostTypeId="2" ParentId="8600" CreationDate="2014-09-18T12:37:31.800" Score="2" Body="&lt;p&gt;There is no uplink in ADS-B. The aircraft is broadcasting information which is received by parties unknown to the ADS-B transmitter. There is no reply and there is no uplink like there is in Mode-S. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The receiving parties listen on 1090MHz for ADS-B broadcast. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A technology related to ADS-B is TIS-B (Traffic Information Service - Broadcast). This is used in the USA to transmit positions of aircraft that are not equipped with 1090ES ADS-B but are detected by FAA radar or UAT ADS-B in an ADS-B like format on 1090MHz. This allows parties listening on 1090MHz for ADS-B traffic to identify non 1090ES equipped aircraft with the same receiver. TIS-B could be seen as form of uplink, but uses the 1090MHz frequency nevertheless as it allows the same ADS-B receiver to be used. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-09-18T17:31:24.653" LastActivityDate="2014-09-18T17:31:24.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8628" PostTypeId="1" AcceptedAnswerId="8630" CreationDate="2014-09-18T14:09:50.557" Score="19" ViewCount="9853" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0703.html&quot;&gt;VFR-on-top&lt;/a&gt; is an IFR clearance in the US that a pilot can request to allow an IFR flight to use VFR altitudes provided that it can remain in VMC. Requesting and receiving a VFR-on-top clearance doesn't cancel the IFR flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When is this clearance useful? It allows the pilot a greater choice of cruising altitudes, but why would a pilot prefer to use VFR-on-top rather than request a different IFR altitude? VFR-on-top adds at least one task to the pilot's workload - maintaining VFR cloud clearance - without reducing the IFR workload.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="572" LastEditDate="2014-09-18T19:10:14.147" LastActivityDate="2014-09-19T19:20:12.047" Title="What is the purpose of VFR-on-top?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8629" PostTypeId="2" ParentId="8628" CreationDate="2014-09-18T15:15:25.947" Score="10" Body="&lt;p&gt;Being in VMC has several benefits over hard IMC, especially if you don't have an autopilot, so being on top has advantages. :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Manual flying with visual reference to the horizon is much easier and less strain than manually flying using instruments for attitude control&lt;/li&gt;&#xA;&lt;li&gt;Being out of cloud enables a pilot to see and avoid traffic&lt;/li&gt;&#xA;&lt;li&gt;Flying in cloud can be bumpy, VFR on top is often much smoother&lt;/li&gt;&#xA;&lt;li&gt;Icing is a hazard when flying in cloud, being on top of them means you won't ice up&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;VFR on top works well when you have a stratus layer that has an even top, not so well when you have clouds at differing levels, so it's not always a viable option. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-09-19T12:38:10.577" LastActivityDate="2014-09-19T12:38:10.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8630" PostTypeId="2" ParentId="8628" CreationDate="2014-09-18T15:28:04.347" Score="20" Body="&lt;p&gt;The VFR on top clearance is often given with a block of altitudes.  Such as this from the reference document &quot;Maintain VFR-on-top at or between six thousand and one zero thousand.”  With this clearance the pilot can fly any altitude they want within this block of altitudes without having to contact ATC for further clearance.  This flexibility can be useful with the conditions are such that the clouds come and go as you fly along.  So if you are cruising along at 6500 and encounter a cloud and need to climb to 8500 to maintain clearance you just do it.  No need to contact ATC and wait for them to ensure they can clear you higher while the clouds keeps getting bigger and bigger in the windshield. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if there are not cloud issues, the ability to change altitudes may be useful in seeking an altitude with more favorable winds.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-09-18T19:02:39.187" LastActivityDate="2014-09-18T19:02:39.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8631" PostTypeId="1" CreationDate="2014-09-18T19:34:00.847" Score="8" ViewCount="467" Body="&lt;p&gt;Is there a mandatory requirement for a Tower Controller working at a Non-Federal Control Tower (NFCT) to have a current FAA medical certificate?  Is a Class III sufficient?&lt;/p&gt;&#xA;" OwnerUserId="3525" LastEditorUserId="62" LastEditDate="2014-09-18T19:47:57.763" LastActivityDate="2014-09-19T15:36:43.363" Title="Is a controller at a NFCT required to have an FAA physical? If so what class?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8632" PostTypeId="2" ParentId="8602" CreationDate="2014-09-18T20:04:24.563" Score="3" Body="&lt;p&gt;It can perform an emergency landing if there is no further damage at tail section such as elevators. On &lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot; rel=&quot;nofollow&quot;&gt;JAL 123&lt;/a&gt; crash, vertical stabilizer was missing but that was not the reason why they crashed. JAL crash occurred because of failure on elevator controls.&lt;/p&gt;&#xA;" OwnerUserId="2190" LastEditorUserId="65" LastEditDate="2015-02-04T19:39:46.077" LastActivityDate="2015-02-04T19:39:46.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8633" PostTypeId="1" AcceptedAnswerId="8635" CreationDate="2014-09-19T08:29:36.070" Score="120" ViewCount="34232" Body="&lt;p&gt;Currently Australia is &lt;a href=&quot;http://www.abc.net.au/news/2014-09-18/prime-minister-to-farewell-troops-at-williamtown-raaf-base/5753396&quot;&gt;deploying F/A-18E/F Super Hornets to the UAE&lt;/a&gt; to fight in Iraq. Obviously the UAE (and Iraq) is a very long way from Australia and well beyond the typical range of one of these aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On TV they literally showed the Australian Prime Minister waving goodbye while the jets took off and flew into the distance, which for some reason seemed odd and made me wonder about how fighter jets are typically ferried to a distant war.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I kind of assumed they were loaded onto an aircraft carrier and shipped there, but Australia doesn't have an aircraft carrier so obviously this isn't the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume they must therefore fly, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do they fly hop to hop within their usual range refuelling at each stop? Where would these stops be? I assume they can't just refuel at a civilian airport in an arbitrary country and would have to be an air force base belonging to a close ally.&lt;/li&gt;&#xA;&lt;li&gt;Do they fly continuously with aerial refuelling? Does the tanker need to make hops to refuel?&lt;/li&gt;&#xA;&lt;li&gt;Do they swap their weapons for extended fuel tanks which provide enough range to fly continuously to the UAE?&lt;/li&gt;&#xA;&lt;li&gt;Are they actually shipped via regular military cargo ship and the &quot;departure&quot; on TV just for show?&lt;/li&gt;&#xA;&lt;li&gt;If they do fly continuously, it seems like flying non-stop for ~13 hours in a cramped fighter pilot cockpit would be unreasonable (even commercial pilots take shifts), or would they fly supersonic and perhaps reduce this to 5 or 6 hours?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Answers don't necessarily have to be Australia -&gt; UAE specific, I'd also be interested to know how the US deployed to Iraq and Afghanistan for example and if the process is consistent or depends on the aircraft and location.&lt;/p&gt;&#xA;" OwnerUserId="3529" LastEditorUserId="1696" LastEditDate="2018-04-29T05:41:43.483" LastActivityDate="2020-09-22T22:15:34.693" Title="How do jet fighters get to war?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;range&gt;&lt;ferry-flight&gt;" AnswerCount="9" CommentCount="9" FavoriteCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="8634" PostTypeId="2" ParentId="8633" CreationDate="2014-09-19T08:47:10.523" Score="29" Body="&lt;p&gt;Good Question! They are typically flown in legs from Australia, or if long distance over water, conduct air - air refuelling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Super Hornets you are talking about will most likely stop at somewhere like Butterworth in Malaysia, then fly onto Dubai, possibly meeting with the MRTT sent the day before to refuel enroute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Australia does not have any Aircraft Carriers so sadly, we have to ferry flight them everywhere.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2014-09-19T08:47:10.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8635" PostTypeId="2" ParentId="8633" CreationDate="2014-09-19T09:39:49.133" Score="111" Body="&lt;p&gt;To answer the list in order:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do they fly hop to hop?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An F-18 can go 3,000km unloaded (ordnance adds a &lt;em&gt;lot&lt;/em&gt; of drag) and that's plenty from Australia. You can get to the Middle East in 4 hops, no air-to-air refuelling required. Although if you do an in-flight top-up you can add more than the regular range because you don't need to burn any fuel getting back up to cruise altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Where would these stops be? Surely not at civilian airports?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aircraft often use civilian airports - they run on Jet-A just like everything else. Fighters were not an uncommon sight at the general-aviation terminal where I'm from. Loaded warplanes are a political issue, unloaded ones are a good day's business for the airport's fuel merchants. (note that fighters are almost never completely unloaded - the ammunition for the gun has a significant effect on the airplane's trim. But you can't see it.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An external fuel tank can be added in place of weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are they actually shipped via regular military cargo ship?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fixed-wing aircraft are typically not boxed for surface shipping. Helicopters are - no wings to remove and rotors can be folded up very easily.&#xA;Carrier-based aircraft will depart from land - the only way you get a Hornet off of a docked carrier is with a crane, so they typically launch everything when still offshore, and load the aircraft the same way on departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USA has enough carriers that they would not deploy a carrier-based fleet like this. If they are adding / replacing aircraft there are probably enough already in Europe - send those where needed and replace them in the normal course of events.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Would they fly supersonic to reduce travel time?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, they won't go supersonic to reduce the flight time. &gt; Mach 1 consumes so much fuel you'd never get there. Fighters have supersonic capability so they can get there or run away as needed, but it's never used for very long. The Concorde was designed from the beginning for Mach 2 cruise, so it didn't use afterburners once at Mach 2. Subsonic flight suffered as a result, fighters would not accept the subsonic flight handling issues as that's rather important to them :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bombers are often deployed directly from home bases. All modern strategic bombers have global range with in-flight refuelling. You don't leave North Dakota, blow up something in Longwayfromherestan and get home for dinner, but you don't land anywhere else either. Yes, it's many hours in the same seat but the military crews are used to it.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="2448" LastEditDate="2014-09-19T15:00:30.920" LastActivityDate="2014-09-19T15:00:30.920" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8636" PostTypeId="2" ParentId="8631" CreationDate="2014-09-19T15:36:43.363" Score="2" Body="&lt;p&gt;Yes, you would need a current medical certificate. Source is &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-93B.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; (page 4).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the above document is for NFCT, they do not mention which class is the minimum. However, I found at other places that for ATC, you do require Class II (sources are &lt;a href=&quot;http://www.ccbc.edu/airtrafficcontrolterminaldegree&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/general/classes/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Second-Class - Commercial Pilot; Flight Engineer; Flight Navigator; or&#xA;  Air Traffic Control Tower Operator. (Note: This category of air&#xA;  traffic controller does not include FAA employee air traffic control&#xA;  specialists).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.richmorflightschool.com/&quot; rel=&quot;nofollow&quot;&gt;flight school&lt;/a&gt; indicates the same:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Applicants must:&lt;br/&gt;&#xA;  possess a current, Class-2 medical certificate issued through an FAA certified examiner&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-09-19T15:36:43.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8637" PostTypeId="2" ParentId="8633" CreationDate="2014-09-19T16:40:17.160" Score="78" Body="&lt;p&gt;I am former fighter pilot:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We often fly &quot;hop to hop&quot; but depending on the total distance, the need for urgency, and the distance over water we also fly with tankers and air refuel. Of course the tankers sometimes don't have the fuel for themselves and for us. In those cases, we'll just leave one tanker and rendezvous with another tanker enroute. Everything is very carefully planned. The longest I spent in an F-16 seat was 14 hours. It wasn't too bad.&lt;/p&gt;&#xA;" OwnerUserId="3534" LastActivityDate="2014-09-19T16:40:17.160" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8638" PostTypeId="2" ParentId="8628" CreationDate="2014-09-19T19:20:12.047" Score="10" Body="&lt;p&gt;In a training environment, VFR-on-top is fantastic.  You can use your IFR clearance to punch through a cloud layer to clear skies on top, practice maneuvers (or what have you), and then shoot an approach back down.  VFR-on-top can turn a bad weather day into a training day, and anytime you can do that (and get real-world actual instrument experience on top of it) is a good day.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-09-19T19:20:12.047" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8639" PostTypeId="2" ParentId="3474" CreationDate="2014-09-19T20:51:56.717" Score="15" Body="&lt;p&gt;Several of the answers here seem to suggest that this only happens in first or business class. While that was historically true, it's not so true anymore. Airlines such as &lt;a href=&quot;http://www.cathaypacific.com/cx/en_US/travel-information/inflight/using-electronic-devices/laptop-power.html&quot; rel=&quot;noreferrer&quot;&gt;Cathay Pacific&lt;/a&gt; and &lt;a href=&quot;http://www.koreanair.com/global/en/traveling/classes-of-service/economy-class.html&quot; rel=&quot;noreferrer&quot;&gt;Korean Air&lt;/a&gt;, for instance, have them at every seat in most (or all?) of their long-haul aircraft. Delta also has it in parts of economy on several of their long-haul configurations as well as in all of economy on their recently-acquired &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-717.html&quot; rel=&quot;noreferrer&quot;&gt;717s&lt;/a&gt; and &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-737-900er-739.html&quot; rel=&quot;noreferrer&quot;&gt;737-900ERs&lt;/a&gt;. You can check with your specific airline or with sites like &lt;a href=&quot;http://www.seatguru.com/&quot; rel=&quot;noreferrer&quot;&gt;Seat Guru&lt;/a&gt; before booking to determine what is available on any given aircraft and at which seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Lnafziger said, some airlines' systems require adapters, while others don't. At least from personal experience, it seems that most of the recent ones do not. On Korean Air, Cathay, and Delta, the plugs are designed to be able to fit any of the standard power plug types (e.g. North American, European, Asian, etc.) Since most new electronic devices use auto-switching power supplies, they should accept the 110V/60Hz supplied by most of these systems, even if they're designed for 220V/50Hz markets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a picture of one of the outlets in economy on the Delta 717s. Notice that the holes are cut such that any of the standard plug types will fit in it. The slot on the bottom is a USB power port.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3ymjy.jpg&quot; alt=&quot;Delta 717 Power Outlet in Economy&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2014-12-19T14:53:51.343" LastActivityDate="2014-12-19T14:53:51.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8640" PostTypeId="2" ParentId="8633" CreationDate="2014-09-19T23:35:16.973" Score="32" Body="&lt;p&gt;Ferry range of an FA18-E/F (with ferry tanks attached) is ~ 1800nm.&lt;/p&gt;&#xA;&lt;p&gt;There are any number of possible routes from YAMB to DHF. The choice of route will be influenced by weather, speed, and  politics (third country over flight and landing rights).  It is also possible to mix ferry and refueling.&lt;/p&gt;&#xA;&lt;p&gt;One could, for example, do &lt;a href=&quot;http://www.gcmap.com/mapui?P=drw,lea,kul,NKW,xch,DPS,VTZ,bom,cmb,yamb-drw-dps-kul-vtz-dhf,dps,yamb-dcn-cck-trv-dhf,yamb-dcn-cck-nkw-dhf&amp;amp;DU=nm&quot; rel=&quot;nofollow noreferrer&quot;&gt;YAMB-DCN-CCK-NKW-DHF&lt;/a&gt; (see image below) with a mid-air refueling between NKW &amp;amp; DHF if one wanted, for whatever reason, to avoid landing in India or Sri Lanka.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IpbIQ.gif&quot; alt=&quot;Map of various routes from YAMB to DHF&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="3540" LastEditorUserId="1696" LastEditDate="2020-09-22T22:15:34.693" LastActivityDate="2020-09-22T22:15:34.693" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8641" PostTypeId="2" ParentId="1609" CreationDate="2014-09-20T11:36:27.630" Score="-4" Body="&lt;p&gt;As you know as altitude increasing pressure and temp both are reducing up to stratosphere after that temp remain constant pressure drop continues so density of air reducing so its create less drag aircraft travel at high speed this pressure loss is overcome by ram pressure rise at the inlet of engine and aircraft required less power to move faster at 36,000 ft to 40,000 ft above more power full engine required to run faster so the blade &#xA;tip does not get stall.&lt;/p&gt;&#xA;" OwnerUserId="3542" LastEditorUserId="2171" LastEditDate="2014-09-20T16:07:33.223" LastActivityDate="2014-09-20T16:07:33.223" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8642" PostTypeId="1" AcceptedAnswerId="8643" CreationDate="2014-09-20T13:38:06.557" Score="29" ViewCount="31119" Body="&lt;p&gt;How will the main rotor torque be balanced if a helicopter doesn't have a tail rotor? &lt;/p&gt;&#xA;" OwnerUserId="3543" LastEditorUserId="3504" LastEditDate="2015-01-01T21:51:56.513" LastActivityDate="2018-10-29T20:05:37.853" Title="How can a helicopter be designed without a tail rotor?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8643" PostTypeId="2" ParentId="8642" CreationDate="2014-09-20T14:21:00.750" Score="57" Body="&lt;p&gt;The torque in a helicopter is generated by the engine driving the main rotor in one direction, which causes the fuselage to spin in the other direction. The tail rotor shaft is horizontally mounted and hence creates it own 'lift' to provide anti-torque. The pitch of the tail rotor gives directional control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Common ways to design a helicopter without a tail rotor:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tandem rotors&lt;/strong&gt; : Two main rotors mounted one in front of the other. The rotor discs spin in opposite directions. All power from the engines is used for lift. Example: &lt;strong&gt;CH-47&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wWQGO.jpg&quot; alt=&quot;CH-47&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Transverse rotors&lt;/strong&gt; : Two main rotors mounted side-by-side. Example: &lt;strong&gt;Kamov Ka-22&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3f/Kamov-Ka-22.jpg&quot; alt=&quot;Ka-22&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Co-axial rotors&lt;/strong&gt; : Two rotor discs are mounted one on top of the other. The engine units power both rotors. This structure requires a very complex swashplate mechanism. Example: &lt;strong&gt;Kamov Ka-25&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a0WFb.jpg&quot; alt=&quot;Ka-25&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Intermeshing rotors&lt;/strong&gt; :  In this main rotor assembly, the two set rotor masts are installed at a slight angle to each other, in a transversely symmetric manner, so that the rotor blades intermesh without colliding with each other. Example: &lt;strong&gt;Kaman K-MAX&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mywa7.jpg&quot; alt=&quot;Kaman K-MAX&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tip jet&lt;/strong&gt; : This is an interesting solution to the no-tail-rotor problem. Instead of driving the rotors with a turboshaft engine, compressed air is sent through nozzles installed at the tips of rotor blades. The engines effectively push against the air rather than the helicopter fuselage. The rotor spins just like a Catherine wheel. Example: &lt;strong&gt;Hiller Hornet&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Mmi2I.jpg&quot; alt=&quot;Hiller Hornet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;NOTAR&lt;/strong&gt; : NOTAR - NO TAil Rotor uses a fan inside the boom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow of air along the tailboom utilizing the Coandă effect. The boundary layer changes the direction of airflow around the tailboom, creating thrust opposite the motion imparted to the fuselage by the torque effect of the main rotor. Example: &lt;strong&gt;MD-900&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DudCP.jpg&quot; alt=&quot;MD-900 Explorer&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Refer to &lt;a href=&quot;http://en.wikipedia.org/wiki/Tail_rotor#Alternative_technologies&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; for more!&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="3142" LastEditDate="2017-07-06T21:31:17.990" LastActivityDate="2017-07-06T21:31:17.990" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8644" PostTypeId="1" CreationDate="2014-09-20T05:06:52.153" Score="11" ViewCount="3326" Body="&lt;p&gt;I am collecting a list of all airports in the world for my project, at present I have 46000 airports in my database but only 7000 airports have IATA code. So my question is, if I only take 7000 airports with IATA code and delete the rest will I lose any major airports or airports with huge traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any airports that have no IATA code but do have a huge passenger traffic or provide connections to major airports?&lt;/p&gt;&#xA;" OwnerUserId="3423" OwnerDisplayName="Nivin Abraham" LastEditorUserId="97" LastEditDate="2014-11-03T00:40:37.507" LastActivityDate="2021-03-18T01:44:27.243" Title="Are there any airports that do not have an IATA code but have a huge number of traffic?" Tags="&lt;commercial-aviation&gt;&lt;airport&gt;&lt;iata&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8645" PostTypeId="1" AcceptedAnswerId="8657" CreationDate="2014-09-21T00:35:15.167" Score="11" ViewCount="1212" Body="&lt;p&gt;I am modeling the lift and drag forces of a wing in software of my own creation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I have a wing which fits the profile of (for example) NACA 0024, it is a simple operation to look up the proper coefficients for lift and drag based on the current angle of attack for the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what happens if I slap an aileron on the trailing edge?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do I need to re classify the wing based on the new geometry?&lt;br&gt;&#xA;Should I treat control surfaces as their own aerodynamic bodies and look for lift/drag tables for them?&lt;br&gt;&#xA;Since this is just a simulator, would it make sense to just offset the current coefficients by some value based on angle of deflection?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am admittedly uneducated in aerodynamics and aviation, so please forgive me if I've come at this problem from entirely the wrong direction.&lt;br&gt;&#xA;Any help or advice would be greatly appreciated!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="3484" LastEditorUserId="1696" LastEditDate="2015-04-22T21:57:23.077" LastActivityDate="2019-06-05T05:55:45.620" Title="How should control surfaces be modeled in simulations?" Tags="&lt;aerodynamics&gt;&lt;flight-controls&gt;&lt;ailerons&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8646" PostTypeId="1" AcceptedAnswerId="8653" CreationDate="2014-09-21T00:57:41.270" Score="40" ViewCount="79219" Body="&lt;p&gt;Why does an aircraft leave a white smoke trail?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/bDPb4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3546" LastEditorUserId="753" LastEditDate="2018-01-21T21:58:46.357" LastActivityDate="2018-01-21T21:58:46.357" Title="Why does an aircraft leave a white smoke trail?" Tags="&lt;jet&gt;&lt;contrails&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8647" PostTypeId="2" ParentId="8646" CreationDate="2014-09-21T01:12:51.333" Score="18" Body="&lt;p&gt;The Blue Angels and other display teams have smoke generators in their jets, which have the specific purpose of generating a smoke trail because it looks cool. Smoke trails at airshows are generally for that purpose. The generators inject a small amount of diesel into the jet exhaust to generate white smoke, and dyed diesel to make coloured smoke.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="946" LastEditDate="2014-09-21T10:14:29.053" LastActivityDate="2014-09-21T10:14:29.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8648" PostTypeId="1" CreationDate="2014-09-21T02:04:49.627" Score="2" ViewCount="1503" Body="&lt;p&gt;Pls help me with these 2 questions&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft is standing on an airfield 220ft above sea level on a day when the barometric pressure at ground level is 1004 mb. If the pilot sets the altimeter to read 220ft on this day, what will it read if the barometric pressure drops to 992 mb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft sets off from airfield A (126 ft above sea level) where the ground pressure is 1010 mb and flies to B (762 ft above sea level) where the ground pressure is 985 mb. If the pilot sets his altimeter (incorrectly) at 26ft at A, what will it read when it lands B? &lt;/p&gt;&#xA;" OwnerUserId="3547" LastEditorUserId="1289" LastEditDate="2014-09-22T10:37:32.653" LastActivityDate="2014-09-22T10:37:32.653" Title="Calculations for altimeter settings for variations in barometric pressure" Tags="&lt;altimeter&gt;&lt;altitude&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2014-09-22T15:31:41.300" ContentLicense="CC BY-SA 3.0" />
  <row Id="8649" PostTypeId="1" AcceptedAnswerId="8661" CreationDate="2014-09-21T02:10:56.303" Score="60" ViewCount="20598" Body="&lt;p&gt;So when I look around on the airport, I don't really see many differently shaped airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They all look pretty much the same, only subtle differences. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aircraftrecognition.co.uk/aircraft_parts.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VlN4p.jpg&quot; alt=&quot;standard jet airliner&quot;&gt;  &lt;em&gt;&lt;sup&gt;Image: Aircraft Recognition&lt;/sup&gt;&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this design so common? Why don't we have more extravagant designs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or am I not looking closely enough to appreciate the differences?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like there could be so much potential for a variety of designs, offering more space and comfort for passengers for example... Or is it too risky to try something new?&lt;/p&gt;&#xA;" OwnerUserId="3548" LastEditorUserId="1289" LastEditDate="2015-06-01T14:28:12.907" LastActivityDate="2021-03-31T04:47:14.230" Title="Why is there really only one basic design for passenger airplanes?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;" AnswerCount="10" CommentCount="7" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="8650" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T02:43:47.317" Score="9" Body="&lt;p&gt;The design is popular because it happens to be the best so far for subsonic large-capacity air travel. Other designs would either be less safe or have more drag, plus, there is not reason to fix what is not broken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Yellowstone_Project#Yellowstone_projects&quot;&gt;flirted with different airliner designs&lt;/a&gt; in the past few years, but it seems that for the time being the most extravagant designs we will have will be the Boeing 787 and Airbus A380.&lt;/p&gt;&#xA;" OwnerUserId="718" LastActivityDate="2014-09-21T02:43:47.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8651" PostTypeId="2" ParentId="8646" CreationDate="2014-09-21T04:16:32.493" Score="28" Body="&lt;p&gt;Most aircraft that leave trails aren't leaving smoke.  It's condensed water vapour; essentially, clouds. These are called &lt;em&gt;contrails&lt;/em&gt;. This can be caused by the water in the engine exhaust condensing, or by the disruption of the air by the passage of the aircraft triggering the condensation of water that was already present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hpPgL.jpg&quot; alt=&quot;747 producing contrails from its engine exahust&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aerobatic aircraft have smoke generators which leave much thicker and more visible trails which can be turned on and off and don't depend on particular atmospheric conditions.  White is most common but other colours are possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v5YCX.jpg&quot; alt=&quot;The Snowbirds with red and white smoke trails&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Blue Angels in your photo are an example of aerobatic aircraft with smoke generators.&lt;/p&gt;&#xA;" OwnerUserId="3550" LastActivityDate="2014-09-21T04:16:32.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8652" PostTypeId="1" CreationDate="2014-09-21T04:59:54.057" Score="10" ViewCount="19467" Body="&lt;p&gt;I want to know: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the fuel consumption of an Airbus A320-200 - 180 Seats, at 100% load factor for a distance of 2000 km?&lt;/li&gt;&#xA;&lt;li&gt;What is the fuel consumption of an Airbus A320-200 - 180 Seats, at 80% load factor for a distance of 2000 km?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3551" LastEditorUserId="1696" LastEditDate="2015-04-22T18:48:22.760" LastActivityDate="2021-01-18T22:42:36.567" Title="How can I calculate the fuel consumption of an Airbus 320-200 at various loads?" Tags="&lt;aircraft-performance&gt;&lt;airbus-a320&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8653" PostTypeId="2" ParentId="8646" CreationDate="2014-09-21T07:26:34.967" Score="75" Body="&lt;p&gt;Actually, there are three types of trails an aircraft can leave in the sky:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;1. Condensation of water vapor in the exhaust gas and/or the wake&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This needs the very cold, very dry air at higher altitudes between 6000m and 12000m. Water vapor in the exhaust stream condenses and, pushing the local air above its saturation water content, forms a white, frozen mist. Also, particles from partially burnt fuel form condensation cores wich stabilise the contrail and let it grow over time from humidity already present in the air. Depending on the atmospheric humidity, these contrails disappear rather quickly by sublimation or can stay in place for hours and even grow into cirrus clouds. They are called &lt;strong&gt;con&lt;/strong&gt;densation &lt;strong&gt;trails&lt;/strong&gt; or short &quot;contrails&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2ASEI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2ASEI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;Cirrus clouds triggered by aircraft contrails (picture &lt;a href=&quot;http://www.pa.op.dlr.de/CONCERT/images/contrail_cirrus.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the added water vapor in the exhaust gas helps in contrail production, the condensation happening in the pressure field around an aircraft can already produce a contrail all by itself. If the relative humidity is close to saturation and the condensed droplets freeze quickly, the aerodynamic contrail will disappear rather slowly. The same condensation happens also at lower altitude but will not leave a contrail  in temperatures above 0°C. Fog (liquid droplets) will vaporize quickly, but when frozen the condensation will last longer, until the water is re-absorbed by the air by &lt;a href=&quot;https://en.wikipedia.org/wiki/Sublimation_(phase_transition)&quot; rel=&quot;noreferrer&quot;&gt;sublimation&lt;/a&gt;, a much slower process than &lt;a href=&quot;https://en.wikipedia.org/wiki/Evaporation&quot; rel=&quot;noreferrer&quot;&gt;evaporation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zjx6w.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zjx6w.jpg&quot; alt=&quot;Engine and aerodynamic contrail forming behind an A340&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;Engine and aerodynamic contrail forming behind an A340 (picture &lt;a href=&quot;http://Engine%20and%20aerodynamic%20contrail%20forming%20behind%20an%20A340&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;2. Smoke from unburnt or partially burnt fuel&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This was prevalent in early jets and allowed to spot them from a distance - just follow the black line, at its tip is an aircraft. Smokeless &lt;a href=&quot;http://en.wikipedia.org/wiki/Combustor&quot; rel=&quot;noreferrer&quot;&gt;combustor cans&lt;/a&gt; which allow more fuel-air mixing put an end to this. For more information I recommend the excellent web page &lt;a href=&quot;http://contrailscience.com&quot; rel=&quot;noreferrer&quot;&gt;contrailscience&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/en1j0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/en1j0.jpg&quot; alt=&quot;B-47 with smoke trail&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;This B-47 uses rockets to accelerate quickly which leave the biggest smoke trail, but also the old J-47 left a lot of smoke behind (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/8/81/Boeing_B-47B_rocket-assisted_take_off_on_April_15%2C_1954_061024-F-1234S-011.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;3. Oil mist or smoke flares&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The third source is shown in your picture: Oil is injected into the hot exhaust stream which forms a dense mist. This can be done with jets and piston engines, and gliders or parachutists use smoke flares. Once they are ignited (in most cases electrically) they burn down and cannot be switched off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3sZVb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3sZVb.jpg&quot; alt=&quot;Smoke flares on the wingtips and fuselage of a glider&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Smoke flares on the wingtips and fuselage of a glider (picture &lt;a href=&quot;http://images.fineartamerica.com/images-medium-large/glider-flying-aerobatics-at-airshow-photo-poster-print-keith-webber-jr.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many more things that can be sprayed from an aircraft (fuel, obviously, when it has to be dumped in an emergency, fertilizer or insecticides, silver iodide to seed clouds), but these are special cases. I encourage you to visit &lt;a href=&quot;http://contrailscience.com&quot; rel=&quot;noreferrer&quot;&gt;contrailscience.com&lt;/a&gt; for an exhaustive list of those other cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p0DHP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p0DHP.jpg&quot; alt=&quot;LS-10 dumping ballast water&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;LS-10 glider dumping ballast water (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/de/9/9c/Wgc-2006-holger.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-01-20T23:40:36.983" LastActivityDate="2018-01-20T23:40:36.983" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8654" PostTypeId="2" ParentId="8652" CreationDate="2014-09-21T08:54:53.557" Score="26" Body="&lt;p&gt;If you need precise values, you need to provide much more detail. Fuel consumption is affected by many parameters; see &lt;a href=&quot;https://aviation.stackexchange.com/questions/8219/where-can-i-find-accurate-information-about-fuel-efficiency-of-airbus-vs-boeing/8221#8221&quot;&gt;this answer&lt;/a&gt; for more detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a precise estimate it will be best to employ a simulation software; see the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/7971/atlantic-fuel-burn-estimations&quot;&gt;this question&lt;/a&gt; for more detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are just interested in a general estimate, the venerable &lt;a href=&quot;http://www.southampton.ac.uk/~jps7/Aircraft%20Design%20Resources/aerodynamics/Breuget%20Equation.htm&quot; rel=&quot;noreferrer&quot;&gt;Breguet equation&lt;/a&gt; will already give good results. First we need to know how much difference the 20% in load factor makes: The &lt;a href=&quot;http://www.icao.int/Meetings/STA10/Documents/Sta10_Wp005_en.pdf&quot; rel=&quot;noreferrer&quot;&gt;average mass of a passenger plus baggage for short-range trips&lt;/a&gt; is 100 kg, so the zero-fuel mass would be &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family#Specifications&quot; rel=&quot;noreferrer&quot;&gt;OEW&lt;/a&gt; + 18 t = 60.6 t in the 100% case and 3.6 tons less in the 80% case. Allow for 3 t of fuel reserves and plug that into the Breguet equation, using a fuel burn of $b_f$ = 0.000018 kg/Ns and a speed of Mach 0.78, which equates to $v$ = 262 m/s in 11.000 m altitude:&#xA;$$m_1 = m_2 \cdot e^{\frac{R\cdot g\cdot b_f}{v\cdot L/D}}$$&#xA;The L/D should be 18 and for the range we use R = 2000.000 m. $m_1$ is take-off mass and $m_2$ landing mass. This gives $m_1$ = 68.54 t for the 100% case and $m_1$ = 64.66 t for the 80% case. To be realistic, you would need to include different fuel flow during climb and descent, but the real value shouldn't be too far from the 5 rsp. 4.7 tons we get from the Breguet equation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that when you repeat the calculation for 5,700 km range, the take-off mass comes out at 78.7 t for the 100% load factor, which is almost exactly the MTOW of the A-320. With 2.3 t of reserves, the Breguet equation gives you exactly the specified performance of the A-320-200. This should give you some confidence in those results.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-09-21T12:39:58.317" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8655" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T09:10:21.037" Score="23" Body="&lt;p&gt;Every time a new aircraft is introduced, the marketing department of the respective manufacturer claims that now a new era of air travel has begun. Remember the claims made at the time when Boeing launched the 747: We would enjoy a big-screen cinema and a bar in the sky, and much the same (plus the option of a flying spa) happened with the A-380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, customers vote with their wallets, and airlines need to earn money, so all those extravagant options wither and everyone comes back to what works best. Aircraft design has matured, and all those claims of blended wing-body configurations will only keep marketing and the press occupied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add to this the constraints of existing infrastructure and excessive regulation (thanks to which we enjoy unparalleled safety in air travel, btw.), and the potential advantage of new configurations will quickly vanish. Just try to find a way to quickly evacuate one of these blended wing-body configurations with 20 seats in a row, and any claimed aerodynamic advantage (which it doesn't have) will be moot.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-21T09:10:21.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8656" PostTypeId="2" ParentId="8648" CreationDate="2014-09-21T09:30:41.637" Score="0" Body="&lt;p&gt;Question 1: 550 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question 2: 660 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(rounded to the next multiple of 10).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Atmospheric pressure drops by 1 mbar for every 8.5 m or 27.7 ft of altitude between 0 and 1000 ft, and the differences of your cases from the standard atmosphere are small, so I did not use corrections.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-21T09:30:41.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8657" PostTypeId="2" ParentId="8645" CreationDate="2014-09-21T09:55:39.693" Score="10" Body="&lt;p&gt;Any control surface changes both local camber and local incidence, so it would be best if you change the coefficients accordingly. If you use a panel code, it would be enough to change the local surface inclination (= the flow direction at the local control point) by the deflection angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need formulas for the coefficients: A control surface with a cord length fraction d (of total chord length) will change the local lift coefficient &lt;span class=&quot;math-container&quot;&gt;$c_l$&lt;/span&gt; with&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\Delta c_l = \sqrt{d}\cdot c_{l\alpha}\cdot sin (\eta),$$&lt;/span&gt;&#xA;where &lt;span class=&quot;math-container&quot;&gt;$\eta$&lt;/span&gt; is the deflection angle in radians and &lt;span class=&quot;math-container&quot;&gt;$c_{l\alpha}$&lt;/span&gt; is the lift coefficient gradient over angle of attack of the original airfoil. The additional lift will act at a point between 50% and 25% of wing chord. The higher value is for very short flaps, the lower for all-flying surfaces (technically 100% flap chord), so a control surface deflection will add a torsional load. Drag will not be affected for small deflection angles, but when they get bigger, first drag rises and then the lift increase becomes nonlinear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you stay in the linear range (15° with 30% flap chord, 25° with 15% flap chord at moderate angle of attack) you can linearly add the flap effect (offset the coefficients). Going beyond that in both deflection angle and angle of attack will need a reduction in flap effectivity which can (in extreme cases) even become control reversal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that the aileron especially will twist the wing such that its effectivity is reduced at higher dynamic pressure. The details of this effect depend on the stiffness of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your example of a NACA 0024 is already so thick that it will not tolerate big flap deflection angles and show separation on the suction side. Good wing thicknesses for subsonic flight are between 12% and 15%, and the most extreme ones (like the root of highly loaded high aspect ratio wings) will still be below 20%. Supersonic wing thicknesses are generally between 4% and 6%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you depend on that control surface for trimming the aircraft, don't let its effectivity decrease (as it would in reality), but give it linear effectivity (without the sine function) into infinity and punish large deflection angles with excessive drag (or whatever runs against your target parameter).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-06-05T05:55:45.620" LastActivityDate="2019-06-05T05:55:45.620" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="8658" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T12:15:46.360" Score="28" Body="&lt;p&gt;If you look around a reasonably active hub airport, you will actually see many different design choices for passenger aircraft, all being produced today:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some have high wings (above the windows), some have low.&lt;/li&gt;&#xA;&lt;li&gt;Some have swept wings, some have straight.&lt;/li&gt;&#xA;&lt;li&gt;Some have engines mounted below the wings, others have them attached to the fuselage.&lt;/li&gt;&#xA;&lt;li&gt;Some have turbofan engines, others have propellers.&lt;/li&gt;&#xA;&lt;li&gt;Some have conventional tailplanes, others have T-tails.&lt;/li&gt;&#xA;&lt;li&gt;Some have two engines, some have four.&lt;/li&gt;&#xA;&lt;li&gt;Most have a long roughly cylindrical fuselage; some have other shapes (consider the 747 whose fuselage cross-section changes dramatically halfway down the plane).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you look at planes optimized for flying similar distances with similar numbers of passengers (compare, for example, Airbus A320 with Boeing 737) they will have the same choices in most of these categories. That's because the choices do make a difference, and for that particular use a particular combination turns out to be economically advantageous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, once you look at planes with &lt;em&gt;different&lt;/em&gt; roles, things change. A 70-seater regional such as the ATR 72 does not look like a scaled-down A320 &lt;em&gt;at all&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Except very coarsely at the level of &quot;long narrow fuselage, one pair of main wings near its center, a group of stabilizers all the way aft, tricycle gear&quot;).&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2014-09-22T10:46:08.337" LastActivityDate="2014-09-22T10:46:08.337" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8659" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T14:56:18.173" Score="30" Body="&lt;p&gt;The aircraft industry did the bulk of its research in the 1920s and 1940s. There were literally dozens of variations of airframe and wings. After some experimenting and theorizing (at NACA, Farnborough and elsewhere), for each design goal/market niche there emerged one &lt;a href=&quot;https://en.wikipedia.org/wiki/Dominant_design&quot; rel=&quot;nofollow noreferrer&quot;&gt;dominant design&lt;/a&gt; that fit the payload to fuel and other constraints and minimized cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pretty much in passenger airplanes was decided by the DC-3 design, and in the jet era, by the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Comet&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5nbXK.jpg&quot; alt=&quot;Comet design evolution&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: &lt;a href=&quot;https://aviation.stackexchange.com/users/524/jan-hudec&quot;&gt;Jan Hudec&lt;/a&gt; points out two significant improvements that the Comet did not have:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Anti-shock_body&quot; rel=&quot;nofollow noreferrer&quot;&gt;anti-shock bodies&lt;/a&gt;, first introduced in &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-16&quot; rel=&quot;nofollow noreferrer&quot;&gt;this design&lt;/a&gt;;&lt;/li&gt;&#xA;&lt;li&gt;moving engines forward and into nacelles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As an aside, there's another widespread addition to designs - &lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;winglets&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://people.bu.edu/fsuarez/Fernando_Suarez_Website/Publications_files/1995_SMJ_Dominant%20Design%20Survival_Suarez_Utterback.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://people.bu.edu/fsuarez/Fernando_Suarez_Website/Publications_files/1995_SMJ_Dominant%20Design%20Survival_Suarez_Utterback.pdf&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Bernie MacIsaac and Roy Langton. (2011) Gas Turbine Propulsion Systems, John Wiley &amp;amp; Sons.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="337" LastEditorUserId="14844" LastEditDate="2019-04-22T09:02:12.510" LastActivityDate="2019-04-22T09:02:12.510" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="8660" PostTypeId="2" ParentId="3300" CreationDate="2014-09-21T15:09:07.803" Score="11" Body="&lt;p&gt;Four rotor copters were actually the first copters...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Raúl Pateras Pescara, Buenos Aires, Argentina, 1916  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nmOtY.jpg&quot; alt=&quot;Raúl Pateras Pescara, Buenos Aires, Argentina, 1916&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Etienne Oehmichen, Paris, France, 1921 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SpZX2.jpg&quot; alt=&quot;Etienne Oehmichen, Paris, France, 1921&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3558" LastEditorUserId="17248" LastEditDate="2016-09-29T19:07:18.380" LastActivityDate="2016-09-29T19:07:18.380" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8661" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T16:33:06.113" Score="41" Body="&lt;p&gt;For most transport aircraft, aerodynamic efficiency is the key parameter as it allows lower fuel consumption. The layouts you see most often are the most efficient known:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For jets low swept wings with engines mounted under and ahead of the wings and conventional tail is most efficient known layout. Tail-mounted engines used to be common on smaller jets, but as that puts lot of bulk far aft, they are worse with respect to &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;noreferrer&quot;&gt;Whitcomb area rule&lt;/a&gt;, worse for weight and balance, and wing-mounted engines also help damp flutter. So new regiojets are switching to engines under wing too.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Propeller aircraft fly slower, so they have straight wings. Low mounted wings are slightly more efficient, but then the plane has to have long gear to maintain sufficient ground clearance for the propellers, so high wings are more common. T-tail is then simply used to put the elevator above the most turbulent wake of wing and engines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only deviations from these three basic layouts are on special-purpose plane that have other more important concern. The most notable is &lt;em&gt;military&lt;/em&gt; cargo planes are generally high-wing so they can sit low on the ground for easy loading and unloading using built-in ramp. Their marked &lt;a href=&quot;http://en.wikipedia.org/wiki/Dihedral_(aeronautics)#Anhedral&quot; rel=&quot;noreferrer&quot;&gt;anhedral&lt;/a&gt; is to avoid overstabilizing the aircraft in roll as both high wing and wing sweep increase roll stability. Earlier regiojet designs used tail-mounted engines for the same reason; to sit lower on the ground so they can be easily loaded via built-in airstairs and these are not too heavy and bulky.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2017-04-19T18:43:33.953" LastActivityDate="2017-04-19T18:43:33.953" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8662" PostTypeId="1" AcceptedAnswerId="8681" CreationDate="2014-09-21T19:13:12.913" Score="5" ViewCount="2266" Body="&lt;p&gt;The Rotax 912 engine has dry sump forced lubrication system. They say rotating the prop in the correct way (counter-clockwise when looking from the prop side) will get the oil from the bottom of the crankcase to the oil tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How does this &quot;force back by blow-by gases&quot; work? Is it air which gets through the carburetors and cylinders to do the crankcase what pushes the oil from the engine? If oil gets from the bottom of the crankcase to the top part of the oil tank, where the &quot;burping&quot; sound emerges then? In the oil line, or at the bottom of the crankcase?  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the oil gets pushed by air, why is it bad to rotate the prop in the opposite direction? Air would get to the bottom of the crankcase and air would get to the oil input line and &quot;burp&quot; at the bottom of the oil tank. But if engine then runs in correct direction again, won't the oil be sucked from the bottom of the oil tank again? My only guess is it won't due to the air in the oil pump which would just spin without sucking any oil...&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3559" LastEditorUserId="64" LastEditDate="2015-01-09T23:52:22.437" LastActivityDate="2015-11-18T14:18:15.000" Title="Why Rotax 912 &quot;burps the tank&quot;?" Tags="&lt;piston-engine&gt;&lt;rotax-912&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8663" PostTypeId="1" AcceptedAnswerId="8722" CreationDate="2014-09-21T19:24:26.657" Score="7" ViewCount="545" Body="&lt;p&gt;When flying the Super Decathlon from the backseat, I can see the manifold pressure (top left corner of the panel) and G-meter (top right corner), and that's it.  This (along with the fact that the guy in the front seat blocks the view of the runway centerline) makes it difficult to get good consistency in landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that in if your airspeed indicator fails &lt;a href=&quot;https://i.imgur.com/o5BCxfB.jpg&quot; rel=&quot;noreferrer&quot;&gt;for some reason&lt;/a&gt; you can simply keep a little throttle in, fly until ground effect, and then bleed off whatever speed remains, but that's inconsistent and ugly.  I'm talking about being able to hit any arbitrary point on the runway &lt;em&gt;ten times in a row&lt;/em&gt;.  I would call that impossible without at least an airspeed indicator, but older, wiser pilots have been doing it for years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How do I make consistent landings from the (instrument-less) backseat?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2018-01-11T10:04:20.497" Title="How do I make consistent landings from the (instrument-less) backseat?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8664" PostTypeId="2" ParentId="8649" CreationDate="2014-09-21T19:50:42.643" Score="8" Body="&lt;p&gt;It would be a risk to try something new.  The airframe builder's goal is to make money and they can do that by improving efficiency vs the previous generation and occupying slightly different niches in the market compared to the competition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the alternatives to the tube and low mounted swept wing?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;High wing.  This often necessitates a T-tail which has inferior safety.  With the low wing the wing and landing gear can be mounted to strong points of the airframe.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Mid wing.  Fighters use this because it's more efficient but it would reduce cargo volume on an airliner.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Blended Wing and Body (BWB).  This design has many passengers away from windows and presents evacuation problems.  It's also easier to pressurize a sphere or cylinder than the BWB shape.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Delta wing.  &lt;a href=&quot;http://seattletimes.com/html/businesstechnology/2002973147_boeingconcepts05.html&quot;&gt;http://seattletimes.com/html/businesstechnology/2002973147_boeingconcepts05.html&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The Boeing Honeydew concept uses a delta wing.  Evidently the low speed handling/safety issue is considered too big a problem.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;5&quot;&gt;&#xA;&lt;li&gt;Canard.  The Boeing Kermit Kruiser.  The plane would get lift from the canard instead of downforce but IIRC the area ruling is more difficult.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="2923" LastEditDate="2014-09-22T12:42:27.313" LastActivityDate="2014-09-22T12:42:27.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8665" PostTypeId="1" AcceptedAnswerId="21258" CreationDate="2014-09-21T22:25:41.060" Score="29" ViewCount="22057" Body="&lt;p&gt;The B-52 was introduced in 1955, and is still used by the US Airforce, and is expected to remain in use till the 2040s. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the A-4 Skyhawk was introduced in 1956 and retired in 1998/2003. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now granted these are completely different aircraft. What I'm wondering, is why one aircraft can remain so useful for so long, while others quickly become obsolete. &lt;/p&gt;&#xA;" OwnerUserId="3049" LastEditorUserId="15311" LastEditDate="2017-12-07T18:09:36.397" LastActivityDate="2017-12-10T11:45:06.423" Title="Why/How is the B-52 still in service?" Tags="&lt;military&gt;&lt;bomber&gt;&lt;strategic-bomber&gt;&lt;b-52&gt;" AnswerCount="8" CommentCount="9" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8666" PostTypeId="2" ParentId="8665" CreationDate="2014-09-21T23:10:54.450" Score="13" Body="&lt;p&gt;The B-52 is essentially nothing more than a cargo truck today. It's still useful in that role, although it's obsolete by most reasonable standards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does help that the B-52 has its engines in nacelles, which simplified engine upgrades. To its cargo truck role, the engine performance matters more than anything. And as an old and simple plane, there's nothing on board which causes expensive repairs. Cargo trucks and the B-52 alike are judged on cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To succeed in its role, other planes have to clean the sky around the B-52. Those planes are subject to much more evolutionary pressure. The F-16, introduced 20 years after the B-52 is already outdated in that role. Currently you'd use the B-2, F-22 and/or F-18E/F. Those planes are much more capable of surviving in contended airspace.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2014-09-21T23:10:54.450" CommentCount="23" ContentLicense="CC BY-SA 3.0" />
  <row Id="8667" PostTypeId="2" ParentId="8649" CreationDate="2014-09-22T00:08:27.863" Score="11" Body="&lt;p&gt;It's called &quot;convergent evolution&quot;. If you have one task to perform, and that task has physical requirements, all designs will eventually look and work alike. There are many side-trips along the way and those side-trips tend to stay around servicing their corner of the species.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Large aircraft are low wing. Exceptions are heavy cargo and short / rough field props like the Dash-8 (big props don't fit on low wings) ( a 747 is not a heavy cargo aircraft. each piece is small)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Everyone puts their engines on the wings. The ones that don't sit very low to the ground and don't have enough clearance. Next best place: the tail. Good luck hanging a Trent 900 on either side of the tail. And the elevator has to move out of the way. The number of engines you have is purely a function of needed vs. available thrust. Notice how the trijet configuration went extinct as more powerful (and reliable) engines evolved.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;all pressurized aircraft have circular cross sections and rounded windows, easier to inflate. Non-pressurized planes still use lots of flat panels.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;fish-type creatures use a single large fin for propulsion. True fish wiggle it side-to-side, aquatic mammals that returned to the sea wiggle it up and down, like the legs they used to have.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Things like winglets, canards and other protuberances are bolt-on fixes for aerodynamic issues discovered after the initial design was completed. They likely won't be there the next time a blank-page design is started.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-09-22T02:52:57.157" LastActivityDate="2014-09-22T02:52:57.157" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8668" PostTypeId="1" AcceptedAnswerId="8685" CreationDate="2014-09-22T03:46:07.997" Score="11" ViewCount="28934" Body="&lt;p&gt;For example, the 747 Wikipedia page says that 1500 747s were produced (that number seems quite low!). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any indication of how many large, commercial aircraft there are, and what the breakdown between passenger and cargo is?&lt;/p&gt;&#xA;" OwnerUserId="3049" LastEditorUserId="13197" LastEditDate="2016-03-25T22:38:06.213" LastActivityDate="2017-07-29T17:13:08.250" Title="How many active large commercial airplanes are there?" Tags="&lt;passenger&gt;&lt;commercial-operations&gt;&lt;cargo&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8669" PostTypeId="2" ParentId="8665" CreationDate="2014-09-22T04:42:13.827" Score="28" Body="&lt;p&gt;It's worth digging into the details. The B-52H, which is the model in service today, was not built in the 1950s but the early 1960s (which, I admit, is not a significant difference).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key, however, lies in the upgrade programs that have happened constantly since the design first hit front lines. It's had airframe life extensions, avionics upgrades, and weapons systems changes around every 10-15 years, with the latest round happening in the last five years. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's the how. The why is that it just happens to be damn good at the roles it is given. &lt;a href=&quot;http://en.m.wikipedia.org/wiki/B-52#Continued_service&quot;&gt;It's also highly reliable despite (because of?) its age, and as of around ten years ago was not excessively expensive to fly&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The B-1 averaged a 53.7% ready rate and the Northrop Grumman B-2 Spirit achieved 30.3%, while the B-52 averaged 80.5% during the 2000–2001 period. The B-52's \$72,000 cost per hour of flight is more than the B-1B's \$63,000 cost per hour, but less than the B-2's \$135,000 per hour.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ultimately it comes down to the fact that properly maintained aircraft seem to have shockingly long service lives. There are still 1930s-era DC-3s and C-47s still flying scheduled freight service in Alaska.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-09-22T04:42:13.827" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8670" PostTypeId="1" AcceptedAnswerId="8672" CreationDate="2014-09-22T08:05:37.033" Score="12" ViewCount="3241" Body="&lt;p&gt;I understand the need of having more wheels when the aircraft is designed to be heavier. The number of wheels per bogie and the number of bogies differ from an aircraft to another. For example, there are some main landing gear compositions (from the lightest to the heaviest aircraft):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A320/B737: two 2-wheel bogies&lt;/li&gt;&#xA;&lt;li&gt;A330/A340/B767: two 4-wheel bogies &lt;/li&gt;&#xA;&lt;li&gt;DC10/MD10: two 4-wheel &amp;amp; one 2-wheel bogies &lt;/li&gt;&#xA;&lt;li&gt;B777: two 6-wheel bogies &lt;/li&gt;&#xA;&lt;li&gt;B747: four 4-wheel bogies &lt;/li&gt;&#xA;&lt;li&gt;A380: two 4-wheel &amp;amp; two 6-wheel bogies&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Given those examples, I guess the maximum number of wheels per bogie is 6 and thus given the number of wheel of the B747's main landing gear, it could have been composed of fewer bogies with more wheels on each (e.g. three bogies: two with 6 wheels and one with 4 wheels). So I wonder if there is an optimal number of wheels per bogie, and if for a given number of wheels it is better to add bogies with fewer wheels per bogie.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="11215" LastEditDate="2017-10-02T15:28:01.187" LastActivityDate="2018-12-06T19:13:48.410" Title="Is there a best number of wheels per bogie?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8671" PostTypeId="2" ParentId="8670" CreationDate="2014-09-22T10:15:19.273" Score="4" Body="&lt;p&gt;The problem is not one of the bogie itself; a bogie could also take 10 wheels or more (An-225). But the superstructure of the aircraft has to withstand the forces expected during landing; and of course the landing gear should be retractable into the body for fuel efficiency and speed. Depending on these constraints (and possibly more, like re-usability over a plane family), aircraft designers have to select appropriate bogie configuration accordingly. Depending on the priorization of the constraints and depending on how the plane evolved from is predecessors, different aircraft designers could come up with different conclusions/solutions even for the same airplane, let alone different airplanes with different superstructures.&lt;/p&gt;&#xA;" OwnerUserId="1745" LastActivityDate="2014-09-22T10:15:19.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8672" PostTypeId="2" ParentId="8670" CreationDate="2014-09-22T10:23:38.657" Score="16" Body="&lt;p&gt;The answer depends on who you ask. The structural engineer would prefer a single wheel, and as few legs as possible, while the aerodynamicist would vote for 8 or 12 wheels, because then the bogie has less frontal area and can be accommodated even in thin wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, less than two wheels would compromise redundancy, and more are needed to reduce local ground pressure. Remember that the A-300B was initially not allowed on some US airports because of a slightly higher ground pressure. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/jet-aviation-on-rough-airfields/7496#7496&quot;&gt;this answer&lt;/a&gt; for more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern designs use two wheels per strut for redundancy when the aircraft is light enough and replace them with a bogie with as many wheels as necessary to carry higher aircraft masses. The A-340-200 has gained a central strut with two wheels (A-340-200/300) rsp. a 4-wheel bogie (A-340-500/600), while the equally large, but lighter A-330 uses just the two 4-wheel main gears without the central gear. Airbus could have used two six-wheel bogies, but preferred to keep commonality with the A-330 gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More than 6 wheels per bogie is very unusual, but there are exceptions: Since the Tu-144 had no thrust reversers, all braking had to be done by the wheel brakes. Additionally, the bogies needed to fit between the intake ducts inside the nacelles, so the final design used 8 wheels with the large housings of the disc brakes sticking out towards the center of the bogie. As @Zeus points out in the comments, these were more precisely 4 dual-tire wheels per bogie: The two tires on each side were mechanically linked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F4Io1.jpg&quot; alt=&quot;Tupolev Tu-144 landing gear&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev Tu-144 landing gear (picture &lt;a href=&quot;http://zizis.livejournal.com/206699.html?thread=3749995&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). This particular aircraft is parked in the back yard of the Aviation Institute in Kazan. If you want to know how this 8-wheeled monster would fit inside a supersonic airliner, read the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/27068/tupolev-tu-144-how-can-the-landing-gear-fit-in-the-small-room-in-the-engine&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/d5GVm.jpg&quot; alt=&quot;First prototype of the B-36&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XB-36 (first prototype of the B-36) taking off (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/9/9d/Convair_XB-36_in_flight_just_after_takeoff_or_just_before_landing_061128-F-1234S-025.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convair experimented with different tire sizes for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_B-36_Peacemaker&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-36&lt;/a&gt; and even a &lt;a href=&quot;https://aviation.stackexchange.com/questions/44237/are-tracked-landing-gear-systems-still-in-use-and-development/44267#44267&quot;&gt;tracked version&lt;/a&gt;. The initial single wheel design resulted in the biggest aircraft tire ever produced, but in the end the conventional (but novel at this time) 4-wheel bogie was preferred because the single wheel had too much ground pressure for most US airbases. Earlier airplanes had used 2-wheel bogies (Tupolev TB-3, Junkers G-38) or a pair of wheels left and right of the strut (Douglas DC-4). Very early large aircraft had to use what was available, so the Caproni 42 bomber of 1918 below had as many main wheels as the TU-144 half a century later (picture &lt;a href=&quot;http://flyingmachines.ru/Images7/Caproni/77-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). The &lt;a href=&quot;http://flyingmachines.ru/Images7/Putnam/German_Giants/138-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zeppelin Staaken&lt;/a&gt; giant aircraft of WW I used the same number of main wheels on a single axle for soft field operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qjcd8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qjcd8.jpg&quot; alt=&quot;Caproni 42 detail with central fuselage and wheels&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When Air India ordered their first A320s, they were afraid the main wheel pressure would be too much for some Indian airfields. Airbus produced a version with a four-wheel bogie instead of the usual two-wheel main gear of the regular A320. When they later ordered the A321, India seemed to have improved their airfields, because the newer planes use the regular two-wheel gear which is mechanically simpler and needs less maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NErPN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NErPN.jpg&quot; alt=&quot;Air India A320&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air India A320 (picture &lt;a href=&quot;http://www.avioesemusicas.com/wp-content/gallery/geral/air_india_a320-231_vt-esj_cn490_old_livery_vobl_14mar09_devesh_agarwal_bangalore_aviation-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-12-06T19:13:48.410" LastActivityDate="2018-12-06T19:13:48.410" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="8673" PostTypeId="2" ParentId="8543" CreationDate="2014-09-22T10:55:46.180" Score="4" Body="&lt;h2&gt;Air Accident Investigation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Evidence available to the air accident investigators can include&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight data recorder.&lt;/li&gt;&#xA;&lt;li&gt;Cockpit voice recorder.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft wreckage.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;residues, burn marks, punctures, tears and evidence of stresses.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;ATC communication recordings and controller statements.&lt;/li&gt;&#xA;&lt;li&gt;Airline records. &#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft maintenance records&lt;/li&gt;&#xA;&lt;li&gt;Pilot schedules, dates of health checks, training, hours on type etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Radar and ADS-B data (position, speed, altitude etc).&lt;/li&gt;&#xA;&lt;li&gt;Technical data transmitted in flight to airline, engine maker etc.&lt;/li&gt;&#xA;&lt;li&gt;Photographs, measurements and other reports from investigators at crash site.&lt;/li&gt;&#xA;&lt;li&gt;Eye-witness accounts from people on the ground.&lt;/li&gt;&#xA;&lt;li&gt;Relevant NOTAMs.&lt;/li&gt;&#xA;&lt;li&gt;Data from other aircraft in the vicinity at the time and in previous and following days (e.g. typical tracks and variations over eastern Ukraine).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the case of MH17 the situation is obviously made more difficult by the armed conflict at the crash site and the wider political conflicts. Investigators have to take into account that some evidence may have been tampered with, destroyed or fabricated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have noted, the purpose of an air-accident investigation is not to determine legal liability. Where needed, there is an entirely separate criminal investigation for that purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until they publish their report, we won't know whether the evidence available to them is sufficient for investigators to make any recommendations for changes by manufacturers, operators or regulators to reduce the number of future future occurrences of this type of incident (e.g. recommending airlines don't fly at any height over areas where there is armed conflict).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Other Investigations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Evidence relevant to other types of investigation might include&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;US records of alleged missile launches detected by strategic/tactical missile detection satellites.&lt;/li&gt;&#xA;&lt;li&gt;Ukrainian alleged intercepts of separatist radio communications.&lt;/li&gt;&#xA;&lt;li&gt;Online material allegedly published by Ukrainian separatists.&lt;/li&gt;&#xA;&lt;li&gt;Online photos and videos alleged to be of Russian missile launchers in transit through the Ukraine-Russia border regions.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is difficult to see how the conditions could ever be conducive to a satisfactory judicial investigation of this material acceptable to all parties with an interest in the incident.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-22T14:00:46.040" LastActivityDate="2014-09-22T14:00:46.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8674" PostTypeId="1" CreationDate="2014-09-22T11:53:06.203" Score="60" ViewCount="97642" Body="&lt;p&gt;There doesn't seem to be any place to bring food or drink.&#xA;And what about WC?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And for single seat combat planes? &lt;/p&gt;&#xA;" OwnerUserId="3575" LastEditorUserId="1696" LastEditDate="2018-04-29T05:39:52.907" LastActivityDate="2018-04-29T05:39:52.907" Title="How do fighter pilots manage food, drink &amp; toilet?" Tags="&lt;military&gt;&lt;pilots&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8675" PostTypeId="1" CreationDate="2014-09-22T11:59:18.397" Score="15" ViewCount="4505" Body="&lt;p&gt;Something I have wondered about recently, since the advent of ICBM's what is the point of long range bombers like the B2? I understand they have longer range and can carry more payload but wouldn't they be easy prey for fighter jets or SAM's? Surely missiles are a much more attractive option. I don't get why the effort and expense goes into bombers?&lt;/p&gt;&#xA;" OwnerUserId="3576" LastEditorUserId="1467" LastEditDate="2017-12-18T08:35:27.423" LastActivityDate="2019-05-08T14:51:17.030" Title="Why do Air Forces still use bombers?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;bomber&gt;" AnswerCount="8" CommentCount="11" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8678" PostTypeId="2" ParentId="8675" CreationDate="2014-09-22T12:49:17.683" Score="9" Body="&lt;p&gt;It's about cost, precision, load, time to target, and risk of nuclear war:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Cost: ICBMs are very expensive, even compared to a B2 bomber as a B2 can be reused over and over&lt;/li&gt;&#xA;&lt;li&gt;Precision: 100 meters or so may not make much difference with a 500 kiloton nuke, but with a 500 pound bomb it's the difference between a hit and a miss&lt;/li&gt;&#xA;&lt;li&gt;Load: an ICBM doesn't have that much lifting capacity, they are designed to carry nuclear weapons which aren't particularly heavy. A B2 can carry up to about 40,000lbs of payload and a variety of conventional bombs at the same time, that's much more than the heftiest ICBM&lt;/li&gt;&#xA;&lt;li&gt;Time to target: an ICBM's suborbital path takes at least 15 minutes from launch to target, and that's once you get authorization and build a targeting package for it, which all takes time. A great deal can happen on the battlefield in just 15 minutes, so conventional ICBMs only make sense against strategic targets which won't move, and where time is not a factor. A bomber can loiter on site for hours waiting for targets of opportunity to present themselves, or provide air support for troops on the ground. Long-range missiles are no good for that&lt;/li&gt;&#xA;&lt;li&gt;Risk of nuclear war: ICBMs were designed for one purpose - nuclear exchange. Several nations have entire defense establishments for the purpose of tracking ICBM launches and responding to them. These nations would need to be notified of a conventional ICBM launch so that they don't react by launching their own nukes. Plus, what if their notification system doesn't work and not everyone gets the message? You'd need an extremely good reason why you would want to risk that!&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;That doesn't mean that conventional ICBMs don't exist, they &lt;strong&gt;may&lt;/strong&gt; have been developed by now in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Prompt_Global_Strike&quot; rel=&quot;noreferrer&quot;&gt;Prompt Global Strike&lt;/a&gt; program in the US. This uses existing launchers but replaces their nuclear payloads, which is relatively low-cost as the launchers have been developed and tested. It may be a useful capability but it would be unlikely to be ever used due to the risks involved. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-09-22T16:35:39.717" LastActivityDate="2014-09-22T16:35:39.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8679" PostTypeId="2" ParentId="8674" CreationDate="2014-09-22T12:55:52.007" Score="30" Body="&lt;p&gt;In WWII long-range propeller fighters were usually fitted with an extraction tube, basically a pipe to pee into. This typically froze up in the cold, so you'd have to be pretty desperate. This is why Chuck Yeager said it was vitally important to pee before going on a mission. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Single seat fighters these days don't have any kind of facilities for that, pilots on long-range missions carry either a bag with absorbing gel in it or a plastic container with the same material in them. The USAF's nickname for these are &quot;piddle packs&quot;. As for eating it's generally field rations, protein bars, candy bars, anything that is compact as space is an issue. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-09-22T12:55:52.007" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8680" PostTypeId="2" ParentId="8675" CreationDate="2014-09-22T13:23:17.127" Score="13" Body="&lt;p&gt;Once you launch an ICBM, you're pretty much committed.  Even if there is a self-destruct on the missile (I don't know, nor am I making that claim.  Additionally, I think debris from such an act would be a big concern.).  A bomber also allows you to send something part of the way, and rattle your sabers in the face of the other party without again having committed to the act of the warhead being launched.  You can always recall a bomber without having to worry about a debris field or other unintended consequences. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the claim that bombers are particularly vulnerable, there are numerous ways they get around this.  For instance the B-2 employs stealth to get around this.  The B-52 can use standoff weapons to reach out to a target (such as cruise missiles or JASM).  Also, the B-52 can use low altitude routes to avoid radar and detection (if you’ve never seen a B-52 do a low level, I recommend you find a route and observe, it’s something else).  And on top of all that, the aircraft have defensive systems to help them on their missions (chaff, flares, RW gear, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, with a bomber, you can employ different types of weapons that give you a broader range of response options.  You can use bombs of anywhere from a 250lb laser/GPS guided bomb to something much larger.  These delivery mechanisms are generally much more accurate than a TBM (Theatre Ballistic Missile) or even an ICBM (InterContinental Ballistic Missile).  Those systems are generally inertially guided (some have GPS capability), which can lead to a larger CEP (circular error of probability), meaning that it may not hit exactly where you aim.  Those systems rely on a much larger warhead to get the job done than bombs from a bomber.  You don't use a Nuke to swat a mosquito, as a bit of military wisdom goes.  And, even ballistic missiles can be intercepted by systems such as the Patriot, so they are not a panacea against being stopped.&lt;/p&gt;&#xA;" OwnerUserId="3268" LastActivityDate="2014-09-22T13:23:17.127" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8681" PostTypeId="2" ParentId="8662" CreationDate="2014-09-22T13:40:38.550" Score="8" Body="&lt;p&gt;The Rotax 912 engine uses a dry sump, and does not have a scavenger pump to return oil to the sump. Instead it uses pressure escaping past the piston rings to force the oil back into the sump.&lt;br&gt;&#xA;The &quot;burp&quot; you hear coming from the (open) oil tank happens when most of the oil in the crankcase has been returned to the tank: the air escaping past the rings bubbles up through the oil tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propeller is pulled through &quot;forward&quot; (in the normal direction of rotation) for a few reasons, mainly that it's the direction that the gearbox &amp;amp; accessories are all &lt;em&gt;designed&lt;/em&gt; to turn. Turning in the normal direction of rotation also ensures that oil is pumped through the rest of the system, particularly the valve train.&lt;br&gt;&#xA;Reverse rotation can pump air into the system which may cause problems if you try to start/run the engine immediately after. I believe the recommended procedure is to &quot;burp&quot; the engine a few times to re-prime the oil system if it's pulled through backwards.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-09-22T13:40:38.550" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8682" PostTypeId="1" CreationDate="2014-09-22T15:28:31.527" Score="18" ViewCount="4851" Body="&lt;p&gt;It's been a while since I tried to read a little about flight mechanics and aerodynamics, but I remember one question I had back then:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the thrust of a common passenger aircraft (A320, B737) greater than its lift-off weight and thus could it take off vertically?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a320family/a320/specifications/&quot;&gt;A320&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max take-off weight   73.5 (78) tonnes&lt;/li&gt;&#xA;&lt;li&gt;Thrust range  98 (120) kN&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;73,5 tonnes = 73500 kg * 9.81 m/s^2 = 721035 N = 721 kN&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If my calculations are correct, it could clearly not (a result like what one would expect intuitively)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But how can the dynamic lift be larger than the weight using comparatively little thrust?&#xA;Rephrased: How can the dynamic lift be larger than the thrust? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an invisible equivalent to gears at work here?&lt;/p&gt;&#xA;" OwnerUserId="3582" LastEditorUserId="3582" LastEditDate="2014-09-22T16:11:06.310" LastActivityDate="2021-02-07T18:21:27.633" Title="Why is lift larger than thrust?" Tags="&lt;lift&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="4" ClosedDate="2021-02-10T00:11:21.390" ContentLicense="CC BY-SA 3.0" />
  <row Id="8683" PostTypeId="1" AcceptedAnswerId="8723" CreationDate="2014-09-22T16:28:39.800" Score="8" ViewCount="2480" Body="&lt;p&gt;There are various ways to find out or at least estimate where cloud bases are, e.g. ATIS/AWOS/ASOS report them directly, PIREPs may mention them, and you can make a rough estimate based on the temperature/dew point spread.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any way to determine (or estimate) where the tops are, assuming that no PIREPs are available?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-09-23T20:25:58.537" Title="Is there any way to determine or estimate where the cloud tops are?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8684" PostTypeId="2" ParentId="8682" CreationDate="2014-09-22T16:35:43.717" Score="23" Body="&lt;p&gt;Thrust is needed to overcome drag, and a good airplane design can create a lot of lift for little drag. In the case of an A-320, the lift-to-drag ratio is 18 in cruise (a little less during take-off), so to lift those 78 tons needs only 4.33 tons of thrust. All it needs is the right amount of forward speed, and the engines only need to maintain this speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders are even more efficient, their L/D can approach 60. A glider of maybe 450 kg mass (= 4412 N weight) will create a drag force of only 74 N, admittedly at a much slower speed than an A-320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be more precise, in a climb the thrust will actually compensate a little of the weight, in addition to the drag, depending on the climb angle. The thrust needs to grow by weight &lt;span class=&quot;math-container&quot;&gt;$\cdot$&lt;/span&gt; sin(&lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt;), where &lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt; is the flight path angle. If the A-320 had enough thrust to lift all its weight, it could take off vertically, flying in a nose-up, vertical attitude. Modern fighter aircraft do really have that much thrust installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mQGFZ.png&quot; alt=&quot;Forces on a climbing aircraft&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This drawing shows a climbing aircraft. There are four forces at work:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Lift L (blue arrow)&lt;/li&gt;&#xA;&lt;li&gt;Drag D (red arrow)&lt;/li&gt;&#xA;&lt;li&gt;Thrust T (green arrow), and&lt;/li&gt;&#xA;&lt;li&gt;Weight m&lt;span class=&quot;math-container&quot;&gt;$\cdot$&lt;/span&gt;g (black arrow)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For a trimmed state, the concatenated arrows should form a closed trapezoid (lightly shaded arrows). Note that both thrust and drag are drawn longer here in relation to weight and lift than they are in reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the why part needs a few more lines. &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;Lift is created by deflecting the airstream over the wings downwards&lt;/a&gt;. This change in momentum is lift, and creating it would be free of drag if the wing's span would be infinite and the air inviscid. In reality, flying causes these drag components:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Lift creation incurs a small backwards-pointing component which is biggest at slow speed and decreases with speed. To be precise: This drag component is proportional to the aircraft's span loading (weight divided by wingspan) and the inverse square of airspeed. It is called induced drag because it could be successfully calculated first with the same equations that describe electric induction.&lt;/li&gt;&#xA;&lt;li&gt;Flying through air causes friction. This friction drag grows almost with the square of airspeed and is proportional to air density and surface area.&lt;/li&gt;&#xA;&lt;li&gt;In inviscid flow, the sum of pressures around a body would just cancel out. In reality, the pressure on the forward-facing sections is normally higher than that on the aft-facing sections. This drag component is called pressure drag and is also proportional to the square of airspeed at the same angle of attack.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;At the speed of best L/D the sum of 2 and 3 is equal to 1, and 2 and 3 are of the same magnitude for a well-designed airplane. High subsonic and supersonic flight adds a fourth component, called wave drag, and it's onset is the reason why the A-320 prefers to fly not much faster than Mach 0.78.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="34686" LastEditDate="2019-08-07T15:08:54.773" LastActivityDate="2019-08-07T15:08:54.773" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="8685" PostTypeId="2" ParentId="8668" CreationDate="2014-09-22T18:00:12.140" Score="15" Body="&lt;p&gt;As mentioned this question is hard to answer very accurately without better access to data. It also depends on your definition of &quot;large, commercial aircraft.&quot; Including all &lt;a href=&quot;http://en.wikipedia.org/wiki/Wide-body_aircraft&quot;&gt;wide-body&lt;/a&gt; aircraft would be a large number of planes, and the totals are constantly changing as aircraft are delivered and retired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airfleets.net/recherche/supported-plane.htm&quot;&gt;This site&lt;/a&gt; will probably be the best resource for this kind of question. The data is probably not 100% accurate but it seems to be close. Other information is also available &lt;a href=&quot;http://www.planespotters.net/Production_List/index.php&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I looked at the widebody models on the first linked site, sorting by status to find how many are in &quot;Active&quot; service. This does not include &quot;Stored&quot; aircraft which will be either put into service or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The models below total: &lt;strong&gt;1026 cargo, 3825 passenger&lt;/strong&gt;. This means about 21% of the 4851 widebodies are cargo aircraft, and widebodies constitute about 24% of the worldwide commercial aircraft fleet of &lt;a href=&quot;http://www.usatoday.com/story/todayinthesky/2013/06/12/boeing-predicts-commercial-aircraft-will-double-by-2033/2416131/&quot;&gt;20000 aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;747&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 652 aircraft in service of 1500 delivered to date. Of these, about 289 are cargo aircraft. Excluding 28 aircraft operated by militaries or other organizations, this leaves about 335 passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;DC-10&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 69 aircraft in service of 446 delivered. This does not include aircraft in military or firefighting services, or the aircraft used by Orbis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A300&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 255 active of 561 delivered. Excluding 6 in military or other service, this leaves 178 in cargo service and 71 in passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;767&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are about 821 767 aircraft in service of 1062 delivered. About 165 are cargo versions, and excluding 16 in military or other service, this leaves 640 in passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A310&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 105 active of 255 delivered. Excluding 17 in military or other service, this leaves 14 in cargo service and 74 in passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;MD-11&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 153 aircraft in service of 200 delivered. Only 3 of these are passenger aircraft. These are &lt;a href=&quot;http://en.wikipedia.org/wiki/KLM#Fleet&quot;&gt;operated by KLM&lt;/a&gt;, and the last scheduled flight is October 25, 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A330&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 1069 active of 1112 delivered. Excluding 22 in military or other service, this leaves 27 in cargo service and 1020 in passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A340&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 289 active of 377 delivered. Excluding 11 in military or other service, this leaves 278 aircraft in passenger service. If there are any versions used only for cargo, there aren't many.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are about 1216 777 aircraft in service of 1230 delivered. About 134 are cargo versions, leaving about 1082 in passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A380&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 139 delivered. There are no cargo variants and none out of service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;787&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 183 delivered. There are no cargo variants and none out of service.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-23T17:09:37.263" LastActivityDate="2014-09-23T17:09:37.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8686" PostTypeId="1" AcceptedAnswerId="8689" CreationDate="2014-09-22T18:54:09.720" Score="97" ViewCount="54798" Body="&lt;p&gt;I noticed that the &quot;new&quot; F-35 still has a GAU-22/A cannon installed in it -- albeit with only  182 rounds (more with ammo pods). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do fighters still have cannons? The day of dogfighting is long over, now it's just fire some missiles and forget.  Even if they expended all their missiles, 182 cannon rounds is only 6 seconds of firing  (I think the GAU is rated to 1800 rpm).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason (and I'm not sure if I should answer my own question) is that they need something to shoot warning shots over the bow of another airplane. But that seems an awful amount of weight for this rare occasion. And it'd mean loading tracer rounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is just a vestigial organ, like the sabres on the side of full dress military uniforms?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="15311" LastEditDate="2020-04-12T15:43:39.797" LastActivityDate="2020-09-12T07:34:41.287" Title="Why do fighter jets still have guns/cannons?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;ordnance&gt;" AnswerCount="11" CommentCount="14" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8687" PostTypeId="2" ParentId="8682" CreationDate="2014-09-22T18:56:29.667" Score="6" Body="&lt;p&gt;Peter's answer is very good, but to explain a little more of the 'why,' consider the forces that are at play. In order for a mass to not accelerate in a given direction, the sum of the forces acting on it in that direction must be zero (or the mass infinite, which brings about a whole new set of problems...) In the case of an aircraft that is cruising, there are 3 important categories of forces to consider: gravity, thrust, and the force of the aircraft hitting the air in which it's flying. The latter category is, of course, the most complicated one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sum of the forces applied to the aircraft by the air that it's running into can be modeled as 3 component forces which are all perpendicular to each other: the net sum of forces pushing the plane backwards (drag,) the net sum of the forces pushing the plane upwards (vertical lift,) and the net sum of the forces pushing the plane to the left or right (I'll call this horizontal lift.) When the plane is not turning, the horizontal lift is zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to maintain a given altitude, the vertical lift must be of equal magnitude to the weight of the airplane (the force applied to it by gravity). In order to maintain a given forward speed, the thrust must be of equal magnitude to the drag (assuming, for the sake of simplicity, that the thrust is pushing the aircraft straight forward.) So, the important thing to notice is that the thrust needs only to counter the &lt;em&gt;backward component&lt;/em&gt; of the forces applied by air hitting the aircraft, not the &lt;em&gt;total&lt;/em&gt; force applied by air hitting the aircraft. In a well-designed aircraft, the upward component of the force of air hitting the aircraft will be much larger than the backward component.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-09-22T18:56:29.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8688" PostTypeId="2" ParentId="8686" CreationDate="2014-09-22T19:32:16.507" Score="64" Body="&lt;p&gt;I guess it's for the same reason that soldiers carry hand-guns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They designed &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot;&gt;the F-4&lt;/a&gt; without a cannon and added them back in 1965.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do go up to intercept a plane, if you do ever get close to it, what then? The &lt;a href=&quot;http://en.wikipedia.org/wiki/AIM-9_Sidewinder&quot;&gt;minimum range of a sidewinder is 2.5 km&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.f-16.net/f-16_armament_article5.html&quot;&gt;This paragraph&lt;/a&gt; says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Starting with block 50 (as far as the F-16 is concerned anyway), provisions have been made to fire the new 'hotter, faster, farther' PGU-28 round. It reputedly travels three times as far as the standard M53 round, effectively closing the gap between the Sidewinder minimum engagement range and the gun's maximum engagement range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Up-close and personal is the norm in peace-time: e.g. the Chinese buzzing American planes n the China Sea; or NATO planes flying to meet Russians in the North Sea or off Alaska. What would you do without a short-range weapon? You would have to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Keep your distance (e.g. run away if the enemy comes too close)&lt;/li&gt;&#xA;&lt;li&gt;Shoot before they get too close (a huge over-reaction)&lt;/li&gt;&#xA;&lt;li&gt;Be unarmed/disarmed at close range (not exactly &quot;armed forces&quot; then, is it).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="556" LastEditorUserId="556" LastEditDate="2014-09-22T23:22:47.010" LastActivityDate="2014-09-22T23:22:47.010" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8689" PostTypeId="2" ParentId="8686" CreationDate="2014-09-22T19:39:15.117" Score="100" Body="&lt;p&gt;The idea that missiles will be all a fighter aircraft needs was prevalent in the late Fifties. The &lt;a href=&quot;http://www.aviation-history.com/mcdonnell/f4.html&quot; rel=&quot;noreferrer&quot;&gt;McDonnell-Douglas F-4&lt;/a&gt; Phantom II carried initially only missiles, but at the start of the Vietnam war this turned out to be inadequate. The long-range missiles back then were rather unreliable, and in a real conflict things turn out always different than anticipated. As &lt;a href=&quot;http://en.wikipedia.org/wiki/Carl_von_Clausewitz&quot; rel=&quot;noreferrer&quot;&gt;von Clausewitz&lt;/a&gt; said, the plan is the first casualty of war.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-4s frequently found themselves in close-combat situations for which they were inadequately prepared. Even today, a gun gives the pilot a lot more options, and if the situation is unclear, close-up visual inspection before shooting is still vital to avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Iran_Air_Flight_655&quot; rel=&quot;noreferrer&quot;&gt;politically embarrassing situations&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the F-4C on, F-4s were equipped with a gun. First in external pods, from the F-4E as an internal gun. What also helped to make the F-4 more effective was better training for pilots and ground crew, so the missiles were in better shape and better applied.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-14T03:59:51.783" LastActivityDate="2020-04-14T03:59:51.783" CommentCount="25" ContentLicense="CC BY-SA 4.0" />
  <row Id="8690" PostTypeId="2" ParentId="8668" CreationDate="2014-09-22T20:21:19.207" Score="7" Body="&lt;p&gt;There are several ways to estimate the answer. One would look at the number of delivered airplanes per year, and the other would start from the total number of passengers per year. See &lt;a href=&quot;http://www.icao.int/Newsroom/Pages/annual-passenger-total-approaches-3-billion-according-to-ICAO-2012-air-transport-results.aspx&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; for data for both methods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus and Boeing together deliver almost 1000 airplanes per year. If we set a lower limit of 150 seats for what counts as a large commercial aircraft, 1000 planes would already be a good estimate for global production. If we now assume that an individual aircraft will fly for 30 years and factor in the growth in delivered airplanes per year, the worldwide fleet would be around 12.000 aircraft. There are a few airplanes which start their life as cargo aircraft, but most are converted from old passenger aircraft. For now, I would assume that all newly built aircraft will go into passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How many airplanes would be needed to ferry 3 billion people per year? Short-range aircraft can fly 5 times a day when well managed, and long-range aircraft still manage more than one flight per day. Since the majority of flights is short range, the average number of flights could be 4, with 230 seats and 75% load factor on average. This comes out to 3.000.000.000 / 4 / 172.5 / 365 = 11.912 planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looks like 12.000 is a reasonable estimate for the worldwide total of large commercial passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using &lt;a href=&quot;http://www.iata.org/whatwedo/Documents/economics/Freight-Analysis-Dec-2013.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAOS number of 16 billion&lt;/a&gt; freight ton-kilometers of air cargo volume worldwide, and guessing an average load of 30 tons over 2000 km, it would need 266.667 flights to ferry this volume. If a freighter flies twice a day, the total number of freighters could be just 365 aircraft. This would be just 3% of the number of passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&#xA;The first estimate leaves out all aircraft smaller than 150 seats, which should be included in the ferrying of those 3 billion passengers. I think my utilization estimate is too high; a better number would be 2 flights per day. This moves the total number of commercial passenger aircraft to 24.000, but includes small ones which a correct answer to your question should not include.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my money is still on 12.000 for aircraft bigger than 150 seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, cargo aircraft should be more numerous; again my utilization is on the high side, I guess. But I would be surprised if there are more than maybe 800 big cargo jets in operation worldwide.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-02T22:09:39.633" LastActivityDate="2014-10-02T22:09:39.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8692" PostTypeId="2" ParentId="8686" CreationDate="2014-09-22T21:13:21.197" Score="54" Body="&lt;p&gt;You can't spoof a bullet with countermeasures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plain fact is that bullets cannot be diverted or fooled, unlike missiles, for which there are flares, chaff and different electronic countermeasures and early warning systems. It' s also much easier to destroy a plane with bullets now than it was a few decades back (during WW1 and 2 for instance). Unless your aircraft has some serious armor plating to guard against explosive  and incendiary rounds which are quite common, it's difficult to guard against bullets&lt;/p&gt;&#xA;" OwnerUserId="3371" LastEditorUserId="1360" LastEditDate="2014-09-25T03:56:45.947" LastActivityDate="2014-09-25T03:56:45.947" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8696" PostTypeId="2" ParentId="8644" CreationDate="2014-09-22T22:26:47.357" Score="7" Body="&lt;p&gt;According to &lt;a href=&quot;https://web.archive.org/web/20140824050909/http://www.airliners.net/aviation-forums/general_aviation/read.main/4910598/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this thread&lt;/a&gt;, pretty much anything with scheduled air service will have an &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Air_Transport_Association_airport_code&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA code&lt;/a&gt; to facilitate booking.&lt;/p&gt;&#xA;&lt;p&gt;From looking at the &lt;a href=&quot;http://www.faa.gov/airports/planning_capacity/passenger_allcargo_stats/passenger/?year=2010&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA data&lt;/a&gt;, it looks like everything with more than 10,000 enplanements (enplanement=1 passenger boards an aircraft) is considered a &amp;quot;primary&amp;quot; airport, and &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airports_in_the_United_States&quot; rel=&quot;nofollow noreferrer&quot;&gt;they all have an IATA code&lt;/a&gt; unless the airport is strictly general aviation and unscheduled service.&lt;/p&gt;&#xA;&lt;p&gt;For these reasons, you probably won't find anything with &amp;quot;huge&amp;quot; passenger traffic but no IATA code. There may be airports with unscheduled service to major hubs, though.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="55483" LastEditDate="2021-03-18T01:44:27.243" LastActivityDate="2021-03-18T01:44:27.243" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8697" PostTypeId="2" ParentId="8649" CreationDate="2014-09-22T22:29:27.187" Score="5" Body="&lt;p&gt;As others have noted, the current general design of passenger aircraft is the result of decades of engineering and research. When all of the requirements are analyzed, this basic layout is the one that provides the best balance of advantages and disadvantages. The infrastructure has also been built around this configuration, which introduces another limitation that a new design would have to work around. While airports were willing to make changes in order to accommodate the A380, a completely different design would probably involve a more drastic change which would be harder to sell to airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the many years in which this design has evolved, many good lessons have been learned. Today's safety record in aviation is a result of these lessons being put into practice to improve the design. For a radical new design, much of this would have to be discarded or at least deeply reviewed. Research and testing would have to be done in many areas to ensure that the important aspects of the design are correctly understood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another key element is certification. In order for the FAA, EASA, etc., to grant a type certificate on an aircraft, there is a long certification process. For a completely different design, the certification would also be completely different. Not only would the designers have to be confident in the new configuration, but they would also have to convince these authorities. This would involve introducing a lot of new information. Recent new aircraft have already been taking longer and longer to certify. Introducing a completely new configuration could take even longer.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-22T22:29:27.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8698" PostTypeId="2" ParentId="8686" CreationDate="2014-09-23T00:43:31.067" Score="33" Body="&lt;p&gt;Better to ask a combat pilot I would think. However, a few points:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The internal gun for the F-35A, &lt;em&gt;including&lt;/em&gt; a full load of ammunition, is less than 500 pounds - this represents about 2.5% of the F-35's total weapons payload capacity. That doesn't really sound too bad. They can save 80 lbs if they choose not to load it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The external gun, which is what the VTOL/Naval B and C models get, is a few hundred pounds heavier than that, but optional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Six seconds is actually a lot of 'gun time' for modern air-to-air systems considering speeds, targeting systems and lethality of the projectiles involved. It's not like WWII anymore where you'd slowly pull up behind a bomber and then have to spend several seconds pumping a bunch of crappy .50-cal lead in, hoping to poke enough holes in an oil cooler to make a difference.&lt;/p&gt;&#xA;" OwnerUserId="3595" LastActivityDate="2014-09-23T00:43:31.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8699" PostTypeId="1" AcceptedAnswerId="8701" CreationDate="2014-09-23T04:23:23.210" Score="17" ViewCount="2142" Body="&lt;p&gt;Pearson airport in Toronto has the airport code YYZ, which does not reflect the name Pearson or the city of Toronto. This seems contradictory to other IATA codes like LGA (Laguardia), JFK (John F Kennedy), LHR (London Heathrow), and DFW (Dallas Fort Worth). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a specific methodology in place for assigning these values? &lt;/p&gt;&#xA;" OwnerUserId="3600" LastActivityDate="2019-04-16T14:12:13.160" Title="What is the methodology for assigning airport codes?" Tags="&lt;airport&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8701" PostTypeId="2" ParentId="8699" CreationDate="2014-09-23T05:15:18.743" Score="18" Body="&lt;p&gt;There are different kinds of codes assigned to airports. &lt;a href=&quot;https://www.iata.org/services/pages/codes.aspx&quot; rel=&quot;noreferrer&quot;&gt;IATA codes&lt;/a&gt;, which are the three letter codes you mention; are for travel industry identification purposes (by the way, these aren't restricted to airports - train stations also have these codes). These are used by airlines and travel agents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other four letter codes are &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization&quot; rel=&quot;noreferrer&quot;&gt;ICAO&lt;/a&gt; codes. These are used for navigation, air traffic and flight planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO codes have a defined standard, each region is assigned a letter and all codes begin with that letter. Canada is assigned a practical &lt;code&gt;C&lt;/code&gt;, US is &lt;code&gt;K&lt;/code&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jyHxi.png&quot; alt=&quot;ICAO code designations from Wikipedia&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IATA codes however, are arbitrary. For some reason, Canada was given 'Y' and so all IATA codes in Canada begin with Y.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is YYC (Calgary), YVR (Vancouver), but then you have YQX (Gander) and YXS (Prince George) and YUL (Montreal-Trudeu).&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-09-23T05:15:18.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8702" PostTypeId="1" AcceptedAnswerId="8704" CreationDate="2014-09-23T06:04:47.183" Score="14" ViewCount="8276" Body="&lt;p&gt;What is the name of the maximum altitude at which a helicopter can fly? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recall it as &quot;vertical limit&quot;, but I can't find a Wikipedia page for it other than a movie of the same title, which seems to concern mountain climbing altitudes.&lt;/p&gt;&#xA;" OwnerUserId="1451" LastEditorUserId="15311" LastEditDate="2017-12-05T20:09:16.033" LastActivityDate="2017-12-05T20:09:16.033" Title="What is the name of the maximum altitude at which a helicopter can fly?" Tags="&lt;helicopter&gt;&lt;terminology&gt;&lt;altitude&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8704" PostTypeId="2" ParentId="8702" CreationDate="2014-09-23T07:15:54.497" Score="20" Body="&lt;p&gt;Like with fixed wing aircraft, it is called the &lt;em&gt;ceiling&lt;/em&gt;. Usually two ceilings are distinguished;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;service ceiling&lt;/em&gt;&lt;/strong&gt;, where the aircraft can still achieve a positive rate of climb of either 100 fpm (propeller) or 500 fpm (jet).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;em&gt;absolute ceiling&lt;/em&gt;&lt;/strong&gt;, the theoretical altitude at which no positive rate of climb can be achieved. In other words: the maximum altitude at which the aircraft theoretically can fly under maximum engine power.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1344" LastEditDate="2016-04-13T13:46:27.547" LastActivityDate="2016-04-13T13:46:27.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8705" PostTypeId="2" ParentId="8686" CreationDate="2014-09-23T10:59:14.390" Score="31" Body="&lt;p&gt;A long time ago I used to build fighter aircraft (yes, with my hands). Anyway, the designers whispered behind their hands that the guns on this particular aircraft were there to make the pilots feel happy. The gunfire vibration tended to destroy the delicate instruments, so they were strongly discouraged from ever firing them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In those days the designers (I was aspiring to be one) said, only half joking, an aircraft is a platform for delivering missiles or bombs, so it is basically a radar and a missile management system. The rest is infrastructure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in folk-parlance pilots like to have guns, in the same way as the air force likes to have pilots - it makes them feel better but is not strictly necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;edit: chatting to my old colleague about this, he said he offered to give a pilot a loudspeaker in his helmet going &quot;Da-Da-Da-Da-Da&quot;, since it would be just as much use and a lot less weight. But the pilot was unimpressed.&lt;/p&gt;&#xA;" OwnerUserId="2374" LastEditorUserId="2374" LastEditDate="2014-09-23T12:07:02.633" LastActivityDate="2014-09-23T12:07:02.633" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8706" PostTypeId="1" CreationDate="2014-09-23T12:08:50.587" Score="7" ViewCount="1796" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;noreferrer&quot;&gt;Aeroflot Flight 593&lt;/a&gt; crashed after the autopilot was partially disabled by applying certain force to the control wheel but the only function which was disabled was controlling the ailerons. This partial disengagement went unnoticed for a number of reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm reviewing the official accident report (text is in Russian, linked to from the Wikipedia article) and here're my findings from there so far.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight manual (cited in the report) is claimed to say that &lt;em&gt;manipulating the control wheel to contradict the autopilot is definitely abnormal and should be avoided. The mechanism for overriding the autopilot is a safety device that engages outside normal operational conditions.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it looks like there some functionality that allows to override the autopilot and partially disconnect it (so that only ailerons are no longer controlled) and it is claimed to be a safety measure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the purpose of this functionality?&lt;/p&gt;&#xA;" OwnerUserId="2759" LastActivityDate="2017-10-27T20:36:04.547" Title="What's the purpose of partial autopilot disengagement after applying certain force to the control wheel?" Tags="&lt;flight-controls&gt;&lt;autopilot&gt;&lt;ailerons&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8707" PostTypeId="2" ParentId="8706" CreationDate="2014-09-23T13:25:15.870" Score="2" Body="&lt;p&gt;Although it doesn't address partial disengagement, this SB gives the reasons why forces on control columns could be used to disengage the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus Service Bulletin (sb) No. &lt;a href=&quot;http://lessonslearned.faa.gov/ChinaAirlines140/SB_A300-22-6021.pdf&quot; rel=&quot;nofollow&quot;&gt;A300-22-6021&lt;/a&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2) Objective/Action  To provide autopilot disengagement by applying a&#xA;  15 daN force on the  control column in go-around mode above 400 feet&#xA;  (radio altitude) this Service Bulletin recommends to modify the&#xA;  software at both flight control Computers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The modified Flight Control Computers will also include­ improvements&#xA;  which have been identified from the last standard. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3). Advantages  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Operational benefit and/or passenger comfort by :&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;autopilot disengagement by 15 daN force on control column during    go-around above 400 feet (radio altitude),&lt;/li&gt;&#xA;  &lt;li&gt;avoidance of unwanted atopilot disengagement when the pilot    takes firmly the control column,&lt;/li&gt;&#xA;  &lt;li&gt;nose dowm improvement to avoid the pitch attitude increase after    main landing gear touch down, &lt;/li&gt;&#xA;  &lt;li&gt;improvement of &quot;LEVEL CHANGE&quot; mode; to avoid the &quot;VMO&quot; overshoot, &lt;/li&gt;&#xA;  &lt;li&gt;&quot;ALT HOLD&quot; mode improvement in heavy turbulence. &lt;/li&gt;&#xA;  &lt;li&gt;improvement of autopilot capacity to counteract strong vertical     gust in cruise.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;n.b. 15 daN = 15 deca-Newtons = 150 Newtons = ~34 lbs.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-23T13:49:42.507" LastActivityDate="2014-09-23T13:49:42.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8708" PostTypeId="1" CreationDate="2014-09-23T13:57:40.367" Score="40" ViewCount="17233" Body="&lt;p&gt;I recently traveled from Stansted, UK to Skavsta, Sweden with Ryanair, and was informed that depending on the weather (it was very foggy), we might end up landing at Arlanda (~150 km from Skavsta) instead. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot later decided to try landing, went down to what felt like 20&amp;ndash;50 meters (I could see the airport as clearly as one can see an airport in thick fog...) and suddenly rose sharply and then leveled out, causing some serious roller-coaster-like ~0g feelings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot then tried a second time and landed without much trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How often does this occur? Was it dangerous? Is it according to standard procedure when approaching an airport in bad weather conditions? What might have caused the pilot to actually land the second time but not the first?&lt;/p&gt;&#xA;" OwnerUserId="3609" LastEditorUserId="946" LastEditDate="2014-09-26T07:22:56.837" LastActivityDate="2015-04-28T18:42:10.503" Title="How common are cancelled landing attempts?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;weather&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8709" PostTypeId="2" ParentId="8708" CreationDate="2014-09-23T14:17:35.027" Score="31" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;Q: Was it dangerous? Is it according to standard procedure when approaching an airport in bad weather conditions?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If the aircraft did not go below the &lt;strong&gt;Decision Height&lt;/strong&gt;, no, it was not dangerous and it was according to standard procedures.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Decision Height&lt;/strong&gt; &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/D.HTM&quot; rel=&quot;noreferrer&quot;&gt;is defined&lt;/a&gt; as&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;DECISION ALTITUDE/DECISION HEIGHT [ICAO Annex 6] - A specified altitude or height (A/H) in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.&lt;/p&gt;&#xA;&lt;p&gt;[...] decision height (DH) is referenced to the threshold elevation.&lt;/p&gt;&#xA;&lt;p&gt;The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;DECISION HEIGHT- With respect to the operation of aircraft, means the height at which a decision must be made during an ILS, MLS, or PAR instrument approach to either continue the approach or to execute a missed approach.&#xA;This height is usually 200ft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This means that when the aircraft arrives at the &lt;strong&gt;DH&lt;/strong&gt;, the Pilot Flying (PF) must have decided whether to land or not. If an abort is initiated, he/she cannot modify the decision (as it would be unsafe)and a new decision has to be made during the new attempt.&lt;/p&gt;&#xA;&lt;p&gt;If the pilot decided to attempt the landing, but conditions change later during the attempt, the pilot can still decide to abort (as in &lt;a href=&quot;http://www.youtube.com/watch?v=F1deY7EkNSA&quot; rel=&quot;noreferrer&quot;&gt;this case&lt;/a&gt;). The decision will be based on the current assestment of remaining available runway, aircraft speed, aircraft attitude and current engine throttle.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Q: What might have caused the pilot to actually land the second time but not the first?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The most likely cause is lack of visibility. In borderline conditions, a plane will normally follow an instrument approach down to decision height. At that height they look up, and if they see the runway clearly they land. If they don't they abort. The first time they didn't see it, and the second time they did.&lt;/p&gt;&#xA;&lt;p&gt;In the general case, &lt;a href=&quot;http://www.skybrary.aero/index.php/Go-around_Decision_Making&quot; rel=&quot;noreferrer&quot;&gt;other conditions that might cause a go-around are&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;lack of preparation – “rushed” approach&lt;/li&gt;&#xA;&lt;li&gt;a late runway or approach procedure change&lt;/li&gt;&#xA;&lt;li&gt;an inadequate approach briefing&lt;/li&gt;&#xA;&lt;li&gt;challenging prevailing wind velocity&lt;/li&gt;&#xA;&lt;li&gt;inappropriate energy management&lt;/li&gt;&#xA;&lt;li&gt;inadequate traffic spacing&lt;/li&gt;&#xA;&lt;li&gt;unfamiliar approach - maybe a straight in non-precision or circling&lt;/li&gt;&#xA;&lt;li&gt;inappropriate aircraft configuration&lt;/li&gt;&#xA;&lt;li&gt;runway surface condition&lt;/li&gt;&#xA;&lt;li&gt;a predicted late touchdown point&lt;/li&gt;&#xA;&lt;li&gt;unexpected runway occupancy after clearance to land&lt;/li&gt;&#xA;&lt;li&gt;degraded aircraft systems status&lt;/li&gt;&#xA;&lt;li&gt;the effect of fatigue&lt;/li&gt;&#xA;&lt;li&gt;the effect of commercial and personal pressure (stress)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As for whether is common or not, I have no statistics at hand, but a go-around is definitely not unheard of. In the &lt;a href=&quot;https://aviation.stackexchange.com/a/8729/1467&quot;&gt;answer&lt;/a&gt; of Richard there is a statistic for a specific airport (Heathrow).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-25T08:10:26.763" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8710" PostTypeId="2" ParentId="8708" CreationDate="2014-09-23T14:19:35.573" Score="20" Body="&lt;p&gt;I don't have any statistics to tell you how &lt;em&gt;common&lt;/em&gt; this is, but I can tell you it's absolutely &lt;em&gt;normal&lt;/em&gt;. I did it myself two days ago in a small Cessna. Wikipedia says &quot;Go-arounds occur with an average rate of 1–3 per 1000 approaches&quot; but doesn't cite a reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term for what you described is a &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Go-around&quot;&gt;go-around&lt;/a&gt;&quot;: the aircraft cannot land safely for one of several reasons so the pilot decides to increase power, climb higher and go around for a second landing attempt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A go-around can be required for various reasons, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pilot cannot see the runway clearly enough&lt;/li&gt;&#xA;&lt;li&gt;There is another aircraft, a vehicle or some obstruction on the runway&lt;/li&gt;&#xA;&lt;li&gt;ATC instructs the pilot to go around&lt;/li&gt;&#xA;&lt;li&gt;A sudden wind shift makes the aircraft's approach unstable&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Based on what you described, it sounds like the aircraft was on an instrument approach, which simply means that the pilot was following a radio or GPS signal to the runway because the fog prevented him from seeing it. The basic idea behind an instrument approach is that you follow the signal down to a pre-defined minimum safe height above ground and at that point if you still can't see the runway and land safely then you have to go around. I guess that your pilot didn't see the runway clearly enough in time and decided to go around, although it could have been for another reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The minimum safe height depends on several factors: the aircraft, the equipment it has, the pilot's training and possibly the airline's own policy on approaches. If the weather is so bad that there is little chance of landing then the pilot can try again as he did in your experience or he can divert to a different airport. Again, there are both legal and company policy considerations on when and where to divert.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-09-23T15:04:07.653" LastActivityDate="2014-09-23T15:04:07.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8711" PostTypeId="2" ParentId="8686" CreationDate="2014-09-23T15:46:10.523" Score="11" Body="&lt;p&gt;While missile and radar systems designs get better they still cannot make a complete positive identification between friend or foe.  So you need to get close enough to visually ID the target.  Now you are in a dogfight situation with distance getting too close for missiles and too far for a gun.  So you need both.  You also still need to train pilots in close in dogfighting techniques and tactics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of this is complicated by the fact that aircraft are sold to many countries.  So the same aircraft may be flown by both sides of a conflict.  So now you need to get very close to see markings and other distinguishing characteristics.  &lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-09-23T15:46:10.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8712" PostTypeId="2" ParentId="8674" CreationDate="2014-09-23T15:59:42.593" Score="13" Body="&lt;p&gt;FWIW, it is not just fighter pilots that have this issue.  Many small private planes have facilitates to relieve one self.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My Cessna 340 had a relief tube with consisted of a narrow funnel with a trigger valve.  You put the liquid (I will leave it to your imagination how you got it there) into the funnel and pulled the trigger.  This opened the valve connected to a plastic tube that exited the aircraft under the tail.  Since the cabin was pressurized there was a pretty descent pressure differential that resulted in a quick evacuation of the funnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft without such systems there are wee-packs that a pilot can buy.  These contain a funnel area (they have different shapes and sizes for men and women) attached to a bag.  The bag contains a powder that turns into a jelly trapping the liquid.  When the flight is complete you dispose of the pack. See &lt;a href=&quot;http://www.sportys.com/PilotShop/product/13089&quot; rel=&quot;noreferrer&quot;&gt;this product&lt;/a&gt; for an example.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="65" LastEditDate="2015-02-12T19:32:41.083" LastActivityDate="2015-02-12T19:32:41.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8714" PostTypeId="2" ParentId="8649" CreationDate="2014-09-23T17:02:24.297" Score="6" Body="&lt;p&gt;I have seen others answer the question of why this shape (aerodynamic efficiency) but not &lt;em&gt;why&lt;/em&gt; it is aerodynamically efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key in producing an aircraft with high Aerodynamic efficiency(lowest drag) is lowest possible wetted area and frontal area while simultaneously generating maximum lift.  Frontal area is just what you think, the lowest possible cross section that you try to push through the air.  Whetted area however is the the area that gets &quot;wet&quot; ie the total surface area of the aircraft.  This means that the best possible shape is a long cigar:  the thinner the better.  Any area that you add to the &quot;tube&quot; is wasted energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simultaneously the wing shape that generates maximum lift with lowest drag is a long thin shape.  This is because wings cause lift primarily by creating negative air pressure by making air flow faster over the top than the bottom.  This effect is destroyed by having a wide, fat wing because the wing can't create the same tight pocket of air differential between top and bottom that a thin wing can.  This is what kills Delta wings and lifting bodies.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.discoverhover.org/infoinstructors/guide8.htm&quot; rel=&quot;noreferrer&quot;&gt;http://www.discoverhover.org/infoinstructors/guide8.htm&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Lift_(force)&quot; rel=&quot;noreferrer&quot;&gt;http://en.wikipedia.org/wiki/Lift_(force)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the speed of the aircraft goes to a larger percentage of the speed of sound however other factors come into play.  The wing must be swept and the wing must be stronger to handle the forces in play so it must be thicker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last portion is the tail in back.  This is just mimicking the arrow: putting the fletching in the back of the arrow creates natural stability by making sure the front of the aircraft stays pointed forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many advantages to other designs, Canards have great stall behavior, lifting bodies have superb strength and therefore safety and tandem wings with struts have great strength and great lift characteristics.  But the airline business is a high volume low margin business so any tiny bit of drag gets voted down when decisions get made.&lt;/p&gt;&#xA;" OwnerUserId="3612" LastActivityDate="2014-09-23T17:02:24.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8715" PostTypeId="1" CreationDate="2014-09-23T17:44:14.563" Score="11" ViewCount="2378" Body="&lt;p&gt;The current Airbus A380-800 could carry over 800 people. Has Airbus planned to build a new, larger version that could carry 1000 or more passengers?&lt;/p&gt;&#xA;" OwnerUserId="3613" LastEditorUserId="62" LastEditDate="2014-09-23T18:49:11.063" LastActivityDate="2015-01-09T05:00:27.100" Title="Has Airbus planned to build a larger version of the A380?" Tags="&lt;commercial-aviation&gt;&lt;airbus&gt;&lt;airbus-a380&gt;" AnswerCount="5" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8716" PostTypeId="2" ParentId="3300" CreationDate="2014-09-23T18:40:07.947" Score="9" Body="&lt;p&gt;There are three challenges for making a market-competitive full scale quadrocopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;1) Energy efficiency&lt;/b&gt;&lt;br&gt;&#xA;The quadrocopter is not an energy-efficient design. Helicopters increase their range by using relatively under-powered engines that take a long time to spool up throttle and try to keep it at relatively constant RPM while changing the pitch of the blades to control the helicopter. While this can be used to control pitch and bank, the quadrocopter controls yaw by changing the RPMs of the motors, which I would think would be difficult, and inefficient to do on a full scale helicopter without some sort of CVT to adjust the RPM of the blades without changing the RPM of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;2) Structural integrity and weight&lt;/b&gt;&lt;br&gt;&#xA;Tail rotor helicopters essentially have a fuselage and a tail boom. The tail boom doesn't even need to be that beefy, because the load on the boom is rather small compared to the load of the main rotor pulling up on the frame of the fuselage. Coaxial helicopters can probably get away with just a fuselage, and no tail boom, and probably have less forces acting on the entire structure in normal operating conditions than conventional helicopters. Quadrocopters have four main rotors. Granted, each of the rotors is approximately 1/4 of the power of the main rotor of a conventional helicopter, but the booms would still need to be able to withstand more than 1/2 of the power of a conventional main rotor - think of the extreme case: you're full yaw - that means two rotors diagonally across from one another are either off, or spinning in the opposite direction, creating either loss of lift, or even down force that the other two rotors have to compensate for by producing two times the thrust/lift. It's a rather common phenomenon among miniature R/C planes and helicopters to be completely overpowered, and much beefier than their full-sized counterparts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;3) Cost of manufacturing&lt;/b&gt;&lt;br&gt;&#xA;It's worth mentioning that a larger rotor is easier, and cheaper to manufacture than three additional engines/motors. I think (I could be wrong) the only reason military helicopters have two engines instead of one big one, is for redundancy. If one gets shot, you still have the second one that you can use to limp back to base, or a friendly location. So when you're looking at a whopping four overpowered engines (see point #1) compared to 1-2 underpowered engines, I would imagine you would be looking at something that costs more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those are the reasons why a quadrocopter has not been scaled up, and become commercially available by a large manufacturer. I'm sure each manufacturer is trying to be the first in that market, but I don't think QUADROcopters will ever become human-piloted. If you were talking about making a MULTIcopter (more than 4 rotors) however, there are a few DIY prototypes out there, and I think they have potential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;4) Addressing the proposals for hybrid systems:&lt;/b&gt;&lt;br&gt;&#xA;As things stand now, conventional helicopters run 1-2 turbines for power. They spin in their optimal RPM ranges, and the pilot uses the collective to change the pitch of the rotor blades to control flight. A hybrid system is appealing for cars because it allows the ICE to run in its optimal RPM range rather than constantly changing RPMs. In rotorcraft this isn't an issue - since they already spin at optimal RPM ranges, a hybrid system would introduce a generator, and batteries to generate and store power for the electric motors to consume. This would add weight, without any particular added benefits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big question is - why bother? What makes quadrocopters better than conventional helicopters? For drones the biggest benefit of quadrocopters is their ease and cost of production. It's cheaper to produce four small electric motors than all the mechanisms for a collective. It's also more robust and easier to service. However, we're talking about different scales and missions. Rotorcraft are already inherently inefficient. Their niche - close air support, and transport to locations where it's difficult to land an airplane. The tendency is to create a hybrid, or make a plane with VTOL capabilities. (Osprey, Yak-141, Harrier, F-35 aka US Yak-141). Quadrocopters may find their niche as cheap utility drones, or surveillance drones, but I think a much more likely design, is the likes of the one shown in Avatar - two counter-rotating shrouded rotors on either side of the fuselage, which can be vectored to control flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technology is ever-changing. Scientists in Russia have miniaturized nuclear reactors and fit them inside missiles. This negates the need for batteries and hybrid systems. If anything, this is the powerplant of choice for large quadrocopter systems, but only time can tell how technology will evolve. Right now, I don't see the benefit of quadrocopter configurations for large rotorcraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;b&gt;Amendment, based on new tech in the market (23.03.2018):&lt;/b&gt;&lt;br&gt;&#xA;A Chinese company is actively marketing their &lt;a href=&quot;http://www.ehang.com/ehang184&quot; rel=&quot;nofollow noreferrer&quot;&gt;EHang 184&lt;/a&gt; autopilot drone air taxi, that uses the quadrocopter design. &#xA;Specs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;100kg payload&lt;/li&gt;&#xA;&lt;li&gt;25min cruising time&lt;/li&gt;&#xA;&lt;li&gt;1hr charging time&lt;/li&gt;&#xA;&lt;li&gt;500km/h cruising speed (very curious to see this)&lt;/li&gt;&#xA;&lt;li&gt;500m cruising altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Basically, one can compare it to conventionally designed &lt;a href=&quot;http://rotorfx.com/aircraft_services/mosquito_helicopter_sales/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mosquito&lt;/a&gt; helicopters. They fly slower, but duration of flight,range, and useful load are significantly higher. Also note that while fueling a helicopter these sizes takes five minutes, the air taxi will spend 2 times longer charging, than it will flying. But this is more of a EM vs IC type issue. Time will tell if quadrocopters can prove they're worth up-scaling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Adding from recent professional experience (09/19/2018)&lt;/strong&gt;&#xA;I was recently asked to develop a quadrocopter concept. While attempting to use electric power, I found that payload weight, and mission flight time drastically increased the weight of the batteries required to fulfill mission parameters, and you ended up with a 3-4 ton four-seat quadrocopter (yikes!). Converting to turboprop solved the weight issue, but dramatically increased cost and complexity. As a result, the decision was made to drastically reduce mission parameters, making for a very short range vehicle, which under normal circumstances would be quite useless. You would need to charge the batteries for several hours to get 15-30min flight time. Either your quadrocopter would be sitting on the tarmac charging, or you would need to swap batteries after every hop, requiring expensive infrastructure at every landing pad. Ultimately the idea was proposed with infrastructure and battery swap, and is awaiting its fate at the hands of upper management, but everyone on our team has already scrapped the project as unfeasible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There ARE a number of upcoming battery technologies that would drastically change the potential of such products, but they're not market-ready yet, mostly in theoretical, conceptual, and testing phases at the moment. Can't say much more on the subject without an NDA, sorry.&lt;/p&gt;&#xA;" OwnerUserId="206" LastEditorUserId="206" LastEditDate="2018-09-19T14:31:51.260" LastActivityDate="2018-09-19T14:31:51.260" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8718" PostTypeId="2" ParentId="8686" CreationDate="2014-09-23T18:48:26.630" Score="14" Body="&lt;p&gt;As missile guidance and tracking systems evolve, so do countermeasures and maneuvers to cause a missile to miss. Planes don't carry that many missiles to begin with, and as mentioned before, missiles also have a minimal range. For all of these reasons, guns are still the only way to hit a plane with modern countermeasures. After all your missiles went for bust, or you're closer than the minimal operating range of your missiles. Turning away to gain distance is usually not an option, because as you increase your distance from the enemy, you open up an opportunity for them to turn in and engage you, not to mention losing airspeed is still generally considered a blunder in air-to-air combat.&lt;/p&gt;&#xA;" OwnerUserId="206" LastActivityDate="2014-09-23T18:48:26.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8719" PostTypeId="2" ParentId="8715" CreationDate="2014-09-23T18:51:10.223" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Has Airbus planned to build a larger version of the A380?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2012 they planned to build a larger version of the A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ausbt.com.au/supersizing-the-superjumbo-1-000-seat-airbus-a380-due-by-2020&quot;&gt;&quot;Airbus says 1,000 seat A380 due 2020&quot;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, manufacturers do change plans from time to time, sometimes in response to market conditions. &lt;em&gt;&quot;Has planned&quot;&lt;/em&gt; is not necessarily the same as &lt;em&gt;&quot;is planning&quot;&lt;/em&gt;. Those plans are not currently (8 Jan 2015) being pursued and consequently, as time goes by without a resumption of those plans, it is increasingly likely that any target dates in those plans may no longer be attained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know &lt;em&gt;do Airbus in January 2015 have active plans to build a larger version of the A380&lt;/em&gt; - that would be a new question.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-01-08T09:43:28.023" LastActivityDate="2015-01-08T09:43:28.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8720" PostTypeId="2" ParentId="8715" CreationDate="2014-09-23T19:00:19.663" Score="14" Body="&lt;p&gt;The answer is clearly &lt;em&gt;yes&lt;/em&gt;: The ratio of wingspan to fuselage length is unusually large for modern transport aircraft. The A380 has a wingspan of almost 80m and a fuselage length of less than 73m, whereas in other modern transport aircraft the fuselage is longer than the wingspan is wide. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus designed the A380 with lots of stretch potential. With the cooperation of engine manufacturers, the A380 may one day have a fuselage length of around 100m. This is greater than the maximum length of 80m used in current airport layouts, but Airbus is betting on operators to urge airports to accomodate a stretched A380, &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Integration_with_infrastructure_and_regulations&quot;&gt;just like they did for the current model's wingspan, weight and height&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 will be the biggest Airbus for the next 30 or maybe even 50 years, so it better offers some growth potential. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-06T21:34:42.750" LastActivityDate="2015-01-06T21:34:42.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8721" PostTypeId="2" ParentId="8708" CreationDate="2014-09-23T19:10:30.703" Score="43" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I could see the airport as clearly as one can see an airport in thick fog...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you saw the runway by looking down from your passenger seat as the airplane passed over the airport on the missed approach, you were looking only through an amount of fog approximately equal to the altitude of the aircraft above the ground. For purposes of discussion, let's say that was 50 meters. The pilot, however, is looking through the front windshield trying to see the runway ahead to position himself for the landing. If he was on a standard 3 degree approach slope, that would mean he is having to look through nearly a kilometer (beware of old man doing math in his head) of fog.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Years ago when I flew for a commuter, I often had to make multiple missed approaches at Pullman, WA, USA in snow storms. My rule was that I would try 3 times before diverting. When we diverted we would often get complaints from passengers about not landing because they could see the airport as we passed over it. I could, too, but only through the cockpit side window, and with featureless snow covered rolling hills, there was no way to position for the landing without losing sight of the airport.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What might have caused the pilot to actually land the second time but not the first?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The thickness of fog or how hard it's snowing or raining is constantly changing. Try again and you may be able to see what you couldn't before. If you can't, maybe try a third time and get lucky. Trying more that that would mean eating into your fuel reserve to get to your alternate, and, just as importantly in my view, pilot fatigue becomes a problem. Plus, you're beginning to seriously blow your schedule.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="944" LastEditDate="2014-09-26T04:11:07.360" LastActivityDate="2014-09-26T04:11:07.360" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8722" PostTypeId="2" ParentId="8663" CreationDate="2014-09-23T19:57:10.463" Score="8" Body="&lt;p&gt;Since nobody else has posted an answer, I follow Dan's suggestion and copy my comment here. Unanswered questions make this site look bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practice, practice, practice. It's for a reason that the pilots who fly consistently good landings are the older ones. And remember where the horizon is in reference to the airframe and how the engine sounds. At approach speed (= at high angle of attack) the aircraft will show large attitude changes for small airspeed changes. Remember how high you are at conspicuous points along the approach, don't be shy to look sideways for this. And keeping a little throttle makes better landings, so don't feel negative about this.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-09-23T19:57:10.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8723" PostTypeId="2" ParentId="8683" CreationDate="2014-09-23T20:25:58.537" Score="6" Body="&lt;p&gt;&lt;a href=&quot;https://www.aviationweather.gov/obs/radar/&quot; rel=&quot;noreferrer&quot;&gt;https://www.aviationweather.gov/obs/radar/&lt;/a&gt; provides cloud tops for weather with precipitation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cloud tops with no precip can be discerned from data provided in the Skew-t log℗ charts that are part of this app &lt;a href=&quot;http://www.skewtlogpro.com/about-skew-t-log-p-charts/&quot; rel=&quot;noreferrer&quot;&gt;http://www.skewtlogpro.com/about-skew-t-log-p-charts/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the temperature and dew point on the skew-t charts are converged you can expect clouds. If the convergence extends into the freezing level indicated on the chart you can expect icing. &lt;/p&gt;&#xA;" OwnerUserId="800" LastActivityDate="2014-09-23T20:25:58.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8724" PostTypeId="2" ParentId="8706" CreationDate="2014-09-23T20:56:59.973" Score="2" Body="&lt;p&gt;The reason for this kind of functionality is that if you are handling the controls with that much force, the autopilot assumes you want to fly and gets out of the way.  The forces needed to do this typically are not the kind produced by incidental contact but rather from purposeful contact.  In the planes I'm familiar with the aural warning system will start announcing &quot;AUTOPILOT&quot; until you hit a button to silence it.  In addition, the autopilot annunciation area will indicate the change in autopilot mode or disconnect.  These indications should be monitored at all times the autopilot is flying and the chain of errors here is: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;inadvertent autopilot disconnection (partial), and &lt;/li&gt;&#xA;&lt;li&gt;failure to properly monitor the airplane.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-09-23T20:56:59.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8725" PostTypeId="2" ParentId="8706" CreationDate="2014-09-23T21:31:26.333" Score="4" Body="&lt;p&gt;The autopilot will disconnect on large control inputs because this is the most intuitive way to control the plane. On Boeing planes, the controls will physically move along with the autopilot. If the plane starts doing something you don't want it to do, the instinctive action is to grab the controls to correct it. While the autopilot button would normally be the way to disconnect the autopilot, it may not be the instinctive way in an emergency, and it can be helpful to already have both hands on the controls when the autopilot disconnects, rather than having one hand disconnecting the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for only disconnecting one part of the autopilot could be to help the pilot. Maybe there is a problem with the elevator controls, or an upset that affects the aircraft primarily in pitch. Maybe the TCAS gives a &quot;climb&quot; command. The pilot wants to take over pitch control to address this situation, but other controls are fine. While the pilot now has control of just pitch, the autopilot is still taking care of the other controls. The autopilot only gives the pilot control of the modes that are being overridden, instead of just turning off and requiring the pilot to deal with all control modes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-23T21:31:26.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8726" PostTypeId="1" CreationDate="2014-09-24T00:05:17.607" Score="10" ViewCount="1932" Body="&lt;p&gt;I understand that 400Hz, 26Vrms power is found in a lot of aviation equipment. But how common is it? Is it in every plane and every instrument or is it restricted to certain sectors, like military, commercial, or private planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it used a lot in ground applications to power aviation equipment, like in a workshop/lab setting?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I ask is that I'm trying to gauge interest in a small 400Hz, 26Vrms power supply for the benchtop (plug it into regular 60Hz 120V power). From what I can see, these are hard to find below a few thousand dollars.&lt;/p&gt;&#xA;" OwnerUserId="3621" LastEditorUserId="1696" LastEditDate="2015-01-27T20:16:22.910" LastActivityDate="2015-01-28T23:28:38.743" Title="How common are 400Hz supplies in aircraft?" Tags="&lt;electrical-system&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8727" PostTypeId="2" ParentId="8686" CreationDate="2014-09-24T03:52:38.357" Score="-1" Body="&lt;p&gt;I would also suppose that cannons/guns would be useful against ground targets in certain situations, e.g. tanks or artillery installments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the A10 Warthog's bread and butter is its main cannon. Though this plane is primarily designed with the elimination of ground targets in mind.&#xA;(As someone noted the A10 is an attack aircraft. I'm merely noting this aircraft's reliance on its cannon for ground attacks as a justification for the above supposition. Fighter jets may occasionally be in situations where attacking ground targets is necessary.)&lt;/p&gt;&#xA;" OwnerUserId="3622" LastEditorUserId="-1" LastEditDate="2014-09-25T08:46:34.617" LastActivityDate="2014-09-25T08:46:34.617" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8728" PostTypeId="2" ParentId="8141" CreationDate="2014-09-24T05:40:52.377" Score="1" Body="&lt;p&gt;&lt;strong&gt;tl;dr: Somewhere between 28.3% and 37.8%.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;U.S.-flagged air carriers operating in the U.S. account for 28.3% worldwide scheduled operations while all air carrier traffic in North America accounts for 37.8% of worldwide traffic. Thus, the sum of all scheduled passenger operations in the U.S. is somewhere between those two figures.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of the airports that participate in the Airports Council International statistics, &lt;a href=&quot;http://www.aci.aero/Data-Centre/Monthly-Traffic-Data/Worldwide-Airport-Traffic-Summary&quot; rel=&quot;nofollow&quot;&gt;37.8% of aircraft movements for the year ending May 2014&lt;/a&gt; were in the North America region, which does not include flights in the Latin America/Caribbean region. It appears that Mexico is included in the Latin America/Caribbean region, so it can be safely assumed that the vast majority, though not all, of the North American region traffic is in the U.S. Canada, of course, is also included in the North American region. The report linked above lists 24,571,773 movements in the North American region out of 64,949,170 for all reporting member airports worldwide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The U.S. Department of Transportation maintains official statistics for U.S. air carriers. According to the U.S. DoT's Bureau of Transportation Statistics, in the year ending June 2014, &lt;a href=&quot;http://www.rita.dot.gov/bts/acts#CustomizeTable&quot; rel=&quot;nofollow&quot;&gt;there were 9,177,347 departures on U.S. airline passenger flights&lt;/a&gt;. Note that 'movements' in the ACI statistics above include both departures and arrivals as separate movements, so for purposes of comparison, the 9.18 million departures would equal 18.35 million movements. In order to get information for the exact same period measured by the ACI report (June 2013-May 2014 vs. the July 2013-June 2014 data in the DoT report,) we can subtract June 2014 departures and add June 2013 departures to the U.S. data. These numbers are given on the same DoT page linked above as 791,896 for June 2014 and 810,721 for June 2013. &lt;strong&gt;This yields 9,196,172 departures or 18.39 million movements, which accounts for 28.3% of ACI's worldwide movements for that period.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that flights on non-U.S.-based airlines arriving in or departing from the U.S. are not included in the U.S. DoT figures, nor are cargo flights or non-revenue flights (such as repositioning flights) included in their figures, so the actual percentage for the U.S. would be somewhat higher than that 28.3% figure, but lower than the 37.8% figure for all of North America.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that the above links are unfortunately not permanently linked to the time series mentioned here. They will both continually be updated with the most up-to-date information, so, if you're viewing this answer significantly after it was posted, the exact figures given in those links will be newer than what I have included in this answer.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2016-05-03T16:28:45.790" LastActivityDate="2016-05-03T16:28:45.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8729" PostTypeId="2" ParentId="8708" CreationDate="2014-09-24T12:25:18.493" Score="12" Body="&lt;p&gt;How common? &lt;a href=&quot;http://www.heathrowairport.com/static/Heathrow_Noise/Downloads/PDF/GoArounds11.pdf&quot; rel=&quot;nofollow&quot;&gt;Heathrow published (PDF)&lt;/a&gt; 0.24% for 2010.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a passenger I have, just, beaten this statistic with one go-around (at LHR, incoming from Sao Paulo, Brasil) in a total of about 200 lifetime arrivals worldwide. &lt;/p&gt;&#xA;" OwnerUserId="3629" LastEditorUserId="65" LastEditDate="2015-04-28T16:43:37.503" LastActivityDate="2015-04-28T16:43:37.503" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8730" PostTypeId="1" CreationDate="2014-09-24T13:02:33.197" Score="4" ViewCount="1660" Body="&lt;p&gt;As the above question states, I'm looking for an open database that I can access. I'm building a plane spotter app, and need a lot of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data needs to be downloaded.&lt;/p&gt;&#xA;" OwnerUserId="3631" LastEditorUserId="97" LastEditDate="2015-05-03T00:51:45.500" LastActivityDate="2020-10-29T16:45:09.857" Title="What open databases with aircraft, airlines and country exist?" Tags="&lt;website&gt;&lt;datasets&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ClosedDate="2020-10-30T11:34:11.713" ContentLicense="CC BY-SA 3.0" />
  <row Id="8731" PostTypeId="1" CreationDate="2014-09-24T14:47:38.417" Score="4" ViewCount="283" Body="&lt;p&gt;I will present my reflection based on the Airbus A300-600ST Beluga and I suppose the reflection is the same with the Boeing B747LCF Dreamlifter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A300-600ST was built because its predecessor (the B377SGT Supper Guppy) was not large enough to transport future aircraft's large pieces. Those pieces are too large to be transported by train or by road.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the A300-600ST's pieces must have been transported to build the aircraft. Some of the A300-600ST's pieces must be larger than the pieces this aircraft is designed to transport. So I'm puzzled because I cannot figure out how large pieces of this heavy transporter were transported to its assembly site. The same reflection goes with the B747LCF.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2020-01-10T16:53:21.837" LastActivityDate="2020-01-10T16:53:21.837" Title="How were large pieces of the A300-600ST and the B747LCF transported?" Tags="&lt;transport-category&gt;&lt;airbus-beluga&gt;&lt;boeing-dreamlifter&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8732" PostTypeId="2" ParentId="8731" CreationDate="2014-09-24T15:01:01.803" Score="6" Body="&lt;p&gt;The answer may be that parts were transported the same way A380 parts were transported&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A380’s size means its fuselage and wing sections are shipped via a surface transportation network that includes specially-commissioned roll-on roll-off ships to carry these sections from production sites in France, Germany, Spain and the United Kingdom to the French city of Bordeaux. From there, sections are transported by barge along the Garonne River to the Toulouse final assembly line.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;From &lt;a href=&quot;http://www.airbus.com/company/aircraft-manufacture/how-is-an-aircraft-built/transport-of-major-aircraft-sections/&quot; rel=&quot;noreferrer&quot;&gt;Airbus - TRANSPORT OF MAJOR AIRCRAFT SECTIONS&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.allaboutguppys.com/beluga/600stf.htm&quot; rel=&quot;noreferrer&quot;&gt;All about Guppys&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A300-600ST was built in Toulouse, France. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tqDsN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the smaller pieces would have fitted into an existing transport aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-24T15:28:24.213" LastActivityDate="2014-09-24T15:28:24.213" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8733" PostTypeId="2" ParentId="8708" CreationDate="2014-09-24T15:29:47.650" Score="9" Body="&lt;p&gt;Aborting a landing attempt is called a &quot;go around&quot;, because the pilots usually choose to turn around and try again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;London Heathrow &lt;a href=&quot;http://www.heathrowairport.com/static/Heathrow_Noise/Downloads/PDF/GoArounds11.pdf&quot; rel=&quot;nofollow&quot;&gt;reported&lt;/a&gt; 551 go arounds in 2010, which is less than 2 per day and represented &lt;strong&gt;0.24%&lt;/strong&gt; of the total arrivals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The topic of go arounds came to light after the &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow&quot;&gt;Asiana 214&lt;/a&gt; crash at San Francisco International last year. According to &lt;a href=&quot;http://www.nbcbayarea.com/investigations/Frequent-SFO-Go-Arounds-Point-to-Safety-Concerns-245438381.html&quot; rel=&quot;nofollow&quot;&gt;this information&lt;/a&gt; based on the first 7 months of 2013, go arounds happened on &lt;strong&gt;1.31%&lt;/strong&gt; of approaches for foreign pilots, but &lt;strong&gt;0.28%&lt;/strong&gt; for domestic pilots (which is close to the figures reported at Heathrow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Information from &lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_91481&quot; rel=&quot;nofollow&quot;&gt;CASA&lt;/a&gt; in Australia says there are over 800 per year there, but no accompanying number of arrivals is provided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using separate statistics, for &lt;a href=&quot;https://www.bitre.gov.au/publications/ongoing/files/domestic_airline_activity_2013a.pdf%20702321%20trips%20domestic/year&quot; rel=&quot;nofollow&quot;&gt;domestic&lt;/a&gt; and &lt;a href=&quot;https://www.bitre.gov.au/publications/ongoing/files/International_airline_activity_CY2013.pdf%20162207%20flights%20intl/year&quot; rel=&quot;nofollow&quot;&gt;international&lt;/a&gt; traffic, there are 702321 domestic flights and 162207 international flights in 2013. If only half of the international flights were landing (the other half departing), this represents 783425 landings. Assuming 850 go arounds per year, that is &lt;strong&gt;0.11%&lt;/strong&gt; of arrivals in Australia. Being averaged over the whole country could account for the lower percentage. Some causes for go arounds such as conflicting traffic would be less common at less busy airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to a consultant on &lt;a href=&quot;http://www.pbs.org/newshour/rundown/airplane-turbulence-how-dangerous-is-it/&quot; rel=&quot;nofollow&quot;&gt;this story&lt;/a&gt;, go arounds occur in &lt;strong&gt;0.20%&lt;/strong&gt; to &lt;strong&gt;0.33%&lt;/strong&gt; of landings, which matches the other statistics.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So the numbers show that go arounds are not that common, but they do happen regularly and exactly how often this happens depends on many factors. It is much safer to stop a landing and try again than to continue with an approach that could &lt;a href=&quot;http://avherald.com/h?article=4369190c&quot; rel=&quot;nofollow&quot;&gt;compromise the safety&lt;/a&gt; of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilots have not established the proper altitude and speed in the approach, they should automatically go around rather than attempt to land. They are also required to go around if they cannot see the runway for visual reference by a certain point. If they do not go around, &lt;a href=&quot;http://avherald.com/h?article=47663f0f&quot; rel=&quot;nofollow&quot;&gt;there may be an investigation&lt;/a&gt;, because this can lead to a &lt;a href=&quot;http://avherald.com/h?article=4379bc53/0002&quot; rel=&quot;nofollow&quot;&gt;landing accident&lt;/a&gt;, which is far more dangerous and costly than just going around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By going around, the pilots are hoping that the weather conditions will change enough for the next approach to be safely possible. Low visibility weather like fog can easily change in a short time, so if the conditions are only slightly worse than what is allowed, it may clear up just enough to allow a safe landing.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-28T18:42:10.503" LastActivityDate="2015-04-28T18:42:10.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8735" PostTypeId="2" ParentId="8731" CreationDate="2014-09-24T19:22:53.947" Score="-1" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;nofollow&quot;&gt;A300-600ST&lt;/a&gt; aircraft were built new. The sections were &lt;a href=&quot;http://www.aerospace-technology.com/projects/stbeluga/&quot; rel=&quot;nofollow&quot;&gt;built by companies within the consortium&lt;/a&gt;, and probably shipped similarly to other Airbus parts to the final assembly location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_Dreamlifter&quot; rel=&quot;nofollow&quot;&gt;747 LCF&lt;/a&gt; aircraft were not built new. The aircraft were acquired second hand from airlines, and sent to Taiwan for the modifications. The modified fuselage sections could have been shipped individually and assembled on site. Shipping options are similar to those of other large aerospace parts and include &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/f/fa/A380_transport_Port_de_Bordeaux.jpg&quot; rel=&quot;nofollow&quot;&gt;sea&lt;/a&gt;, &lt;a href=&quot;http://www.triumphgroup.com/companies/triumph-aerostructures-vought-aircraft-division/products/fuselage-panels&quot; rel=&quot;nofollow&quot;&gt;rail&lt;/a&gt;, and &lt;a href=&quot;http://cargofacts.com/special-delivery-courtesy-of-the-an-124/&quot; rel=&quot;nofollow&quot;&gt;air&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-09-24T19:22:53.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8736" PostTypeId="1" AcceptedAnswerId="8738" CreationDate="2014-09-24T20:37:29.500" Score="7" ViewCount="2089" Body="&lt;p&gt;In the 1990s there used to be two basic types of instrument approaches: precision and non-precision. How many different kinds are there now, and what are the differences. &lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1696" LastEditDate="2015-04-22T17:27:50.713" LastActivityDate="2015-04-22T17:52:39.250" Title="Are there types of instrument approaches besides precision and non-precision?" Tags="&lt;instrument-flight-rules&gt;&lt;iaps&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8737" PostTypeId="2" ParentId="8617" CreationDate="2014-09-24T20:52:36.157" Score="1" Body="&lt;p&gt;To provide instrument instruction the instructor must posses a valid CFI certificate with an &quot;instrument airplane&quot; rating.  This is irrespective of the type of training device or airplane used with the caveat the instructor needs to be rated for the airplane (either flown or being simulated).  In other words, if you cannot instruct in an airplane, you cannot instruct in a training device either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The applicability of using the AATD is more of a program certification than an instructor pilot certification issue as there are different levels of training and special certifications for certain levels of training devices and simulators.  See 14 CFR 61, 141, 142 for details about training programs and AATD use.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-09-25T03:02:31.033" LastActivityDate="2014-09-25T03:02:31.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8738" PostTypeId="2" ParentId="8736" CreationDate="2014-09-24T23:16:04.887" Score="6" Body="&lt;p&gt;All approaches can still be categorized as a precision or non-precision.  Some of the terminology has changed, radar approaches are becoming less common and and GPS approaches are becoming more common, but the fundamentals are the same.  Precision approaches still provide glideslope guidance, and non-precision approaches do not.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be important to note that many flight computers blur the lines some with GPS approaches.  There are approaches where the plate still calls the bottom altitude an 'MDA' (instead of 'DH' or 'DA') as you would in a normal non-precision approach, but the flight computer will generate a custom glide slope to that point.  Because this is generated artificially inside your aircraft and not schematically planned by a certified official, this still only qualifies as non-precision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, if you're trying to pick up instrument flying after a long break, you'll still be good to go with your basic understanding of precision versus non-precision approaches.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-09-24T23:16:04.887" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8739" PostTypeId="2" ParentId="8608" CreationDate="2014-09-25T01:47:31.383" Score="1" Body="&lt;p&gt;One option is to experience hypoxia in a &lt;strong&gt;controlled&lt;/strong&gt; setting first, such that you know what altitude you might start feeling symptoms around and which symptoms are the ones you tend to express.  The FAA offers a training course for this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/pilots/training/airman_education/aerospace_physiology/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/pilots/training/airman_education/aerospace_physiology/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user1037" LastActivityDate="2014-09-25T01:47:31.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8742" PostTypeId="1" CreationDate="2014-09-25T06:31:46.020" Score="3" ViewCount="1366" Body="&lt;p&gt;I realize this is slightly off topic, but there's no other SE site that it would at all fit into.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I was just thinking about Neil Armstrong, and I wondered how many confirmed, and/or possible, kills he had in combat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried to look it up, but couldn't find anything with Google.&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2014-09-25T08:12:46.270" Title="How many kills did Neil Armstrong have?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-09-25T14:39:07.380" ContentLicense="CC BY-SA 3.0" />
  <row Id="8743" PostTypeId="2" ParentId="2822" CreationDate="2014-09-25T07:22:11.487" Score="3" Body="&lt;p&gt;The answer to the question is yes, there are limits. I'll expand for ICAO regulated airports, but this is also true for FAA ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO defines an area surrounding a runway, called runway strip, which purpose is to:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;a) to reduce the risk of damage to aircraft running off a runway; and&#xA;b) to protect aircraft flying over it during take-off or landing operations.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;A water runway strip would not reduce the risk of damage to aircraft running off a runway. It would in fact increase it, so a runway strip cannot be made of water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The size of the runway strip depends on the type of runway, but it ranges 150 m to 0m (zero)  in width, and it must extend 30 to 60 m beyond each end of the runway (or the end of the stopways, if there are any).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the runway strip contains at least the runway (and its stopways) and extends beyond it on its ends, and sometimes (depending on the type of runway) it also extends to the sides of the runway, and it defines the limits to how close a runway can be to water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going even further, ICAO defines a Runway End Safety Area (RESA) for some types of runways which further increases the minimum distance of water to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports such as Sint Marteen, where the runway is almost 190m from the water, are just examples of how the runway strip and the RESA are applied as safety measures against aircraft running off a runway.&lt;/p&gt;&#xA;" OwnerUserId="1128" LastActivityDate="2014-09-25T07:22:11.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8744" PostTypeId="2" ParentId="8674" CreationDate="2014-09-25T07:37:29.323" Score="15" Body="&lt;p&gt;The U2 has a kind of toaster for heating ration packs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Funny story told to an ex-RAF friend of mine when he was based in Cyprus:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Guy on a U2 mission over the USSR puts his lunch on and carries on with the mission. Suddenly he heard an enormous bang and his canopy was covered un red stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He panics thinking he's been hit, starts looking everywhere for damage to both him and the aircraft (one would presume he put the lack of pain down to adrenaline).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After a while he realises there is no damage and he is not hurt. Turns out he had forgotten about the tomato-based thing he put in the heater and it had violently exploded.&lt;/p&gt;&#xA;" OwnerUserId="3645" LastActivityDate="2014-09-25T07:37:29.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8745" PostTypeId="2" ParentId="8633" CreationDate="2014-09-25T07:54:51.427" Score="14" Body="&lt;p&gt;They may do hop to hop or they may use inflight refueling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course that opens up the problem of the tankers having enough fuel. Not all tankers can re-fuel in the air, but some can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the RAF did the Black Buck raids in the Falklands war (~12000km), they were offered the use of US Stratotankers. They decided it would not work because the Stratotankers cold not refuel in the air (perhaps they can now, I do not know).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They used their own Victors, which &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Refuelling.plan.black.buck.svg#mediaviewer/File:Refuelling.plan.black.buck.svg&quot;&gt;refueled each other&lt;/a&gt;, ultimately leaving the Vulcan to carry on on its own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, you could use tankers that are already positioned on route, which was the USAF does when it B-52 strike the middle east from their bases in continental US&lt;/p&gt;&#xA;" OwnerUserId="3645" LastActivityDate="2014-09-25T07:54:51.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8746" PostTypeId="2" ParentId="3510" CreationDate="2014-09-25T08:04:52.270" Score="3" Body="&lt;p&gt;Fatigue basically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A carrier landing is often referred to as a (hopefully) controlled crash. Navy aircraft are built much stronger than land-based aircraft for that reason. If you can avoid subjecting your aircraft to those sort of conditions, then why wouldn't you?&lt;/p&gt;&#xA;" OwnerUserId="3645" LastActivityDate="2014-09-25T08:04:52.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8747" PostTypeId="2" ParentId="8742" CreationDate="2014-09-25T08:12:46.270" Score="6" Body="&lt;p&gt;None, his combat unit was ground attack, not air to air, so it is unlikely he ever was involved in air to air combat. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-09-25T08:12:46.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8748" PostTypeId="2" ParentId="8665" CreationDate="2014-09-25T11:57:15.050" Score="27" Body="&lt;p&gt;The B-52 is nothing more than a massive bomb-truck, so it doesn't need a whole lot of improvements. If it ain't broke, don't fix it. It's not pretty, fast, stealthy, or smart. It's a vehicle to get a whole lot of bombs from point A to point Boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did you know the USA military still uses the M2 Browning machine gun from WWII?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-52s are great when you want to say &quot;F--- you and everything within 5 miles of you&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I leave with an old saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cluster bombs from a B-52 are very accurate. They are guaranteed to hit the ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="62" LastEditDate="2017-12-07T20:02:46.317" LastActivityDate="2017-12-07T20:02:46.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8749" PostTypeId="1" AcceptedAnswerId="9691" CreationDate="2014-09-25T12:06:16.047" Score="6" ViewCount="270" Body="&lt;p&gt;I recently discovered the existence of &lt;a href=&quot;https://en.wikipedia.org/wiki/Commercial_aircraft_sales_and_leasing&quot; rel=&quot;nofollow&quot;&gt;CASL&lt;/a&gt; and I understand they buy a lot of new aircraft (e.g. BOC aviation ordered more than &lt;a href=&quot;http://www.air-cosmos.com/2014/08/25/24802-boeing-boc-aviation-en-prend-82-pour-8-8-md&quot; rel=&quot;nofollow&quot;&gt;80 B737's&lt;/a&gt; and about &lt;a href=&quot;http://aviationweek.com/farnborough-2014/asia-pacific-lessors-place-orders-158-a320s&quot; rel=&quot;nofollow&quot;&gt;40 A320's&lt;/a&gt; few weeks ago). I imagine those aircraft are used for temporary operations (e.g. during scheduled maintenance or waiting for an aircraft to be delivered) by regular airliners, charters, lines with demand growing faster than expected, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the number of aircraft they buy, a significant part of the traffic must be operated by these aircraft. Is there some statistics about the number of aircraft and/or the number of flights performed with an aircraft owned by leasing companies compared to flights performed with aircraft owned by airlines themselves?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="97" LastEditDate="2014-11-15T01:49:23.357" LastActivityDate="2014-11-15T01:49:23.357" Title="What is the proportion of active aircraft from CASL (commercial aircraft sales and leasing)?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8750" PostTypeId="1" CreationDate="2014-09-25T14:20:57.923" Score="6" ViewCount="1090" Body="&lt;p&gt;When I read articles or blogs online about GA flying in Europe I get the impression that it's not unusual for European GA pilots to have FAA licenses and fly N (US) registered aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never seen any numbers mentioned so I don't know how common this really is, whether they hold only FAA licenses or also European ones etc. But in general, as a European GA pilot, what is the benefit of operating an N-reg aircraft rather than a locally registered one?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-09-26T00:35:54.837" Title="Why do GA pilots in Europe operate N-reg (US) aircraft?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8751" PostTypeId="1" AcceptedAnswerId="8752" CreationDate="2014-09-25T14:35:19.060" Score="5" ViewCount="1510" Body="&lt;p&gt;I just read the &lt;a href=&quot;http://www.ntsb.gov/news/2010/100318.html&quot; rel=&quot;nofollow&quot;&gt;NTSB press release&lt;/a&gt; of Northwest Airlines Flight 188 that flew more than one hour without making any radio contact. I imagine there may be many causes for losing radio contact with the ground (distraction, electrical failure,...) and I found a &lt;a href=&quot;http://www.aeronewstv.com/fr/article/1790-comment-se-deroule-une-interception-en-vol.html&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt; (in French) saying that one way to solve the situation is to send a fighter to have a closer view of the situation and possibly assist the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if the situation of losing contact with an airplane is frequent? I imagine it happens between one and ten times per month over a region as big as the USA, but that is just a guess.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1696" LastEditDate="2015-10-19T19:11:19.220" LastActivityDate="2018-12-14T17:03:21.370" Title="How often is communication lost with aircraft?" Tags="&lt;radio-communications&gt;&lt;lost-communications&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8752" PostTypeId="2" ParentId="8751" CreationDate="2014-09-25T15:34:55.830" Score="3" Body="&lt;p&gt;According to this &lt;a href=&quot;http://ipv6.faa.gov/data_research/research/med_humanfacs/oamtechreports/1990s/media/AM93-20.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA paper&lt;/a&gt;, Table 3, ASRS reports were analyzed for 16 months between 1978 and 1979. This included 553 incidents where the recipient was not monitoring, which seems to be the closest category to loss of communications. This equates to a little more than 1 incident a day. Note that this only includes incidents that were reported, and air traffic has increased since then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/safety/acp/Inactive%20working%20groups%20library/ACP-WG-C-8/WGC8%20-%20WP12%20-%20Lessons%20learnt%20from%20day%20to%20day%20voice%20Communication.doc&quot; rel=&quot;nofollow&quot;&gt;This report&lt;/a&gt; contains info from ICAO in in Europe. The focus is on the security issues from unresponsive aircraft. In just the northern region, there were 230 flights over just 6 months in the beginning of 2004. This number inclues airlines, business jets, and military transports. This frequency is a little higher than the previous report, but is more recent and probably includes less flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other reports like &lt;a href=&quot;http://asrs.arc.nasa.gov/docs/rs/45_Delayed_Pilot_Recognition_in_Lost.pdf&quot; rel=&quot;nofollow&quot;&gt;this one&lt;/a&gt; don't include a time frame for the reports analyzed, but look at other factors involved. For example, pilots with fewer hours and GA pilots are more likely to be involved in such an incident. The average duration of these incidents was 7.6 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://asrs.arc.nasa.gov/publications/directline/dl6_lost.htm&quot; rel=&quot;nofollow&quot;&gt;This page&lt;/a&gt; also has some good information about this type of incident, including a list of some of the many possible reasons for lost communications and excerpts from some of the reports.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-25T16:18:49.707" LastActivityDate="2014-09-25T16:18:49.707" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8753" PostTypeId="2" ParentId="8751" CreationDate="2014-09-25T15:47:37.667" Score="2" Body="&lt;p&gt;I think losing contact for an hour is unusual, but not being in contact with ATC for a few minutes is pretty common.  On a cross the US flight you might hear 5-6 incidents.  Most of these seem to occur as planes are handed off from different sectors that use different frequencies.   It not uncommon for the pilot to tune in the incorrect frequency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, as aircraft descend into fields with obstacles (ex. mountains) it is not unusual to lose contact.    As you fly along you sometime hear ATC attempting to contact a plane and get no reply.  If you have just heard that call sign you might volunteer to give the aircraft a call and then act as a relay.  For example, you are over some place and hear &#xA;ATC: &quot;KingAir 123 contact center on 123.55&quot;&#xA;KA123:   no response.&#xA;ATC: &quot;KingAir 123 contact center on 123.55&quot;&#xA;KA123:   no response.&#xA;ATC: &quot;KingAir 123 over someplace contact center on 123.55&quot;&#xA;You: &quot;Center, N12345, we are over someplace, would like us to try to contact KA 123?&quot;&#xA;ATC Center: &quot;N12345, affirmative, contact KingAir 123 and ask them contact center on 123.55&quot;&#xA;You: &quot;KingAir 123, N12345, center would like you to contact them on 123.55&quot;&#xA;KA123: &quot;Contact Center 123.55, thanks N12345&quot;&lt;/p&gt;&#xA;" OwnerUserId="2953" LastEditorUserId="2953" LastEditDate="2014-09-25T15:55:47.543" LastActivityDate="2014-09-25T15:55:47.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8754" PostTypeId="1" AcceptedAnswerId="8765" CreationDate="2014-09-25T17:22:32.223" Score="6" ViewCount="3382" Body="&lt;p&gt;When planes engage with guns, many of the shots are misses... what happens to the bullets? Do they kill people on the ground and damage facilities? Do we have any records of this happening?&lt;/p&gt;&#xA;" OwnerUserId="2554" LastActivityDate="2014-09-26T11:08:52.867" Title="Where do all the bullets end up?" Tags="&lt;safety&gt;&lt;fighter&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ClosedDate="2014-09-26T17:24:39.313" ContentLicense="CC BY-SA 3.0" />
  <row Id="8755" PostTypeId="2" ParentId="8754" CreationDate="2014-09-25T18:29:40.963" Score="4" Body="&lt;p&gt;They can kill people or cause property damage.  They probably won't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane is at sufficient altitude and shoots a bullet straight down, the bullet will encounter enough air resistance to slow to terminal velocity.  It won't continue at the speed that it was when it was shot.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same problem occurs with celebratory gunfire.  If you're shooting at an angle less than 40 degrees, that can prove very dangerous.  But straight up in the air, it probably won't be going fast enough on the way down to hurt a normal person.&lt;/p&gt;&#xA;" OwnerDisplayName="user1037" LastActivityDate="2014-09-25T18:29:40.963" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8756" PostTypeId="2" ParentId="8754" CreationDate="2014-09-25T19:48:12.430" Score="6" Body="&lt;p&gt;Falling bullets are similar to falling stones, albeit with higher density and higher terminal velocity. Small ones won't do much damage, but I don't want to be hit by one from a 37mm cannon. Same goes for shrapnel: Flak/AA-guns could not fire steeper than approx. 85° to prevent the gun crews to be hit by their own shrapnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One airplane became famous (at least in pilot's folklore) for the ability to shoot itself down. According to that rumor, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Republic_F-105_Thunderchief&quot; rel=&quot;noreferrer&quot;&gt;Republic F-105&lt;/a&gt; could outrun its own bullets in a shallow dive at supersonic speed. When the bullets, having been fired in horizontal flight, slowed down due to aerodynamic friction and went down in the usual parabola, an accelerating, diving plane could catch up with the bullets. The relative speed between both would be small, however, so the kinetic energy would cause less damage than bullets straight from a gun.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-26T11:06:21.480" LastActivityDate="2014-09-26T11:06:21.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8757" PostTypeId="2" ParentId="8754" CreationDate="2014-09-25T21:34:12.060" Score="4" Body="&lt;p&gt;You are not the first person to worry about this.  In the 1942 war movie &lt;em&gt;Mrs. Miniver&lt;/em&gt; a principal character is killed by stray bullets from an aerial dogfight.  This was considered quite realistic as rounds fired in a low-altitude dogfight often had plenty of kinetic energy when they hit the ground.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2014-09-25T21:34:12.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8758" PostTypeId="1" CreationDate="2014-09-25T21:34:16.930" Score="6" ViewCount="2731" Body="&lt;p&gt;For the sake of this question let's assume that the considered aircraft is an A320. The question is what is the sign of the aerodynamic $C_{n_q}$ coefficient? In another word, when the aircraft starts rolling, will the aircraft experience sideslip and if yes in which direction (and most of all why) ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instinctively, I would say that if the right wing (seen from behind) goes down (positive roll rate), it will be delayed compared to the left one, however I already read somewhere that the coefficient tends to be zero (no sideslip induced). I even heard some aeronautical engineers say that it is the opposite...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If needed, we can set that the x-axis is pointing backward and z down.&lt;/p&gt;&#xA;" OwnerUserId="113" LastEditorUserId="22726" LastEditDate="2019-10-06T01:12:17.437" LastActivityDate="2020-04-25T20:30:44.643" Title="What is the direction of the sideslip induced by roll on a conventional aircraft?" Tags="&lt;aerodynamics&gt;&lt;flight-dynamics&gt;&lt;roll&gt;&lt;sideslip&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8759" PostTypeId="2" ParentId="8736" CreationDate="2014-09-25T22:45:57.303" Score="4" Body="&lt;p&gt;The FAA now issues Operations Specification C052 (&lt;em&gt;Straight-in Non-Precision, APV, and Category I Precision Approach and Landing Minima - All Airports&lt;/em&gt;) to Part 135 (and probably very similar for Part 121) air carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that Ops Spec, they list three categories of approaches:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Nonprecision Approach Procedures Without Vertical Guidance&lt;/li&gt;&#xA;&lt;li&gt;Approaches With Vertical Guidance (APV), and&lt;/li&gt;&#xA;&lt;li&gt;Precision Approach Procedures (ILS, MLS, &amp;amp; GLS)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The basic difference between the categories is whether or not you have vertical guidance that can be used for the approach and the degree of accuracy provided by the underlying navaid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some Flight Management Systems (FMS's) which calculate the vertical navigation (VNAV) component for nonprecision approaches that would not otherwise have it.  These &quot;pseudo-glideslopes&quot; are for reference only and the pilot is responsible for verifying that all crossing restrictions are still made.  &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-04-22T17:52:39.250" LastActivityDate="2015-04-22T17:52:39.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8760" PostTypeId="2" ParentId="8750" CreationDate="2014-09-26T00:35:54.837" Score="6" Body="&lt;p&gt;It's usually cheaper to go to the US and earn an FAA license and then fly N-registered aircraft in Europe than it is to get a European license. However, an N-registered aircraft needs to be maintained to FAA standards by FAA licensed mechanics. &lt;/p&gt;&#xA;" OwnerUserId="3654" LastActivityDate="2014-09-26T00:35:54.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8761" PostTypeId="2" ParentId="8751" CreationDate="2014-09-26T03:27:08.177" Score="3" Body="&lt;p&gt;I think it happens all the time actually. Most of the time its likely not reported. When I did my first solo cross country in a 152, my radio button went out while using VFR flight following. Perhaps they did report it, but they likely just thought it was a new pilot not knowing what he was doing. It was really distracting for myself at the time as a pilot in training. I could hear them talking about me and it took a while to understand that they were not hearing my responses. As a pilot, you are supposed to squawk 7600 to let them know you lost your radio. At the time though, I couldn't remember if it was 7500 or 7600. I knew one of them was for the radio and the other was for a highjacking, and I wasn't needing a fighter jet for my broken radio.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2014-09-26T03:27:08.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8762" PostTypeId="1" AcceptedAnswerId="8763" CreationDate="2014-09-26T03:30:22.460" Score="2" ViewCount="2365" Body="&lt;p&gt;As a goal, I would like to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limit the difficulty of the class B airspace by staying at uncrowded areas&lt;/li&gt;&#xA;&lt;li&gt;Minimize the time it takes to get into the city&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2014-09-26T03:48:02.277" Title="What is the easiest way for a new private pilot to visit Manhattan?" Tags="&lt;airport&gt;&lt;navigation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8763" PostTypeId="2" ParentId="8762" CreationDate="2014-09-26T03:48:02.277" Score="11" Body="&lt;p&gt;All of NYC's airspace is crowded, so there's no escaping that! :) The controllers are very friendly and accommodating though, so don't be afraid. If they're curt, it's just to keep everyone safe. As for airports, there are 4 GA airport options you're most likely gonna consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;KLDJ in Linden, NJ. It's a 5m cab ride to the train station into the city. Uncontrolled field, tons of news helicopters based here. It's pretty cheap (around $20/night if I recall) and fairly convenient, but the uncontrolled field is under an 800' Class B shelf at Newark and could be stressful. Expect very bare bones facilities - you can get fuel, but there's no terminal building to speak of.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;KTEB in Teterboro, NJ is the GA airport for most jets that come into the city. It's the closest airport to midtown, and you'll pay a very pretty penny here, tie-downs are at least \$50/night, and fuel will be around \$9/gallon. This is a hectic option, but it has a tower and is close to the city, so for a quick overnight stop without fuel it may be the best option. Expect to be the only piston on the ramp.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;KFRG in Farmingdale, NY (Long Island). Very busy GA airport abuzz with training. Pretty cheap (~$15/night tiedowns), but did I mention that it's busy? You may burn up 1h of hobbes time on the ground waiting to take off if you depart during peak times. You can catch a cab to LIRR which will get you into the city.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;KHPN, in White Plains, NY. Mix of GA, training, and a couple commercial carriers like JetBlue. Prety cheap ($~20/night tiedowns) and a short hop away from Metro-North which will have you in the city in about 30 minutes. Controlled field, at 2500' below the Class B shelf. Fairly busy, but certainly managable with the top notch controllers working NY's airspace.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Whichever airport you choose to go to, absolutely get flight following or file IFR. All of the towers in the area expect you to be handed off from NY Approach and will not be happy if you call them directly out of the blue.&lt;/p&gt;&#xA;" OwnerUserId="2124" LastActivityDate="2014-09-26T03:48:02.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8764" PostTypeId="2" ParentId="8675" CreationDate="2014-09-26T07:56:35.440" Score="3" Body="&lt;p&gt;Bombers are used much less then they used to be in the piston era. But ICBMs are not the replacement except in nuclear deterrent role. ICBMs are for nuclear attacks only (as already explained in the other answers). In most other roles bombers are replaced by:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fighters/attack aircraft. A flight of smaller aircraft can do same or more damage than a large one and they have more options evading or even defending against various threats.&lt;/li&gt;&#xA;&lt;li&gt;Cruise missiles. They are not any faster than fighter, but flying 100 ft above ground level they are extremely difficult to detect and intercept.&lt;/li&gt;&#xA;&lt;li&gt;UAVs. While they are no match for a fighter and don't have as large payload, they can also fly very low to avoid detection, some are additionally stealth and it's less of a problem if one is lost.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Where bombers are still useful and will likely remain is surprise long-range missions. Bombers can strike almost anywhere in the world from their home base with some aerial refueling. That can be prepared quickly and without having to move many units to forward bases which could warn the enemy. While fighters are also capable of in-flight refueling, they would need to refuel more often and they have no provision for crew rest. B-2 missions often take 30-40 hours.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-09-26T07:56:35.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8765" PostTypeId="2" ParentId="8754" CreationDate="2014-09-26T09:52:00.410" Score="8" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Do they kill people on the ground?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Almost certainly a few do.&lt;/p&gt;&#xA;&lt;p&gt;People struck by falling bullets are more likely to die than people shot directly. The chances of a particular bullet falling onto a person are very small but over the decades, many many bullets have been fired by aircraft.&lt;/p&gt;&#xA;&lt;h2&gt;Handgun bullets&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Between the years 1985 and 1992, doctors at the King/Drew Medical Center in Los Angeles, California, treated some 118 people for random falling-bullet injuries. Thirty-eight of them died.&lt;/p&gt;&#xA;&lt;p&gt;Bullets fired into the air during celebrations return at a speed fast enough to penetrate the skin and cause internal damage to other organs in the path of the migrating bullet. The bullet’s velocity required for skin penetration is between 148 and 197 feet per second. A velocity of less than 200 feet per second, which is easily obtained by a celebratory gunfire, is capable of fracturing bone and even causing intracranial penetration [4]. Spent bullets have the capability of reaching up to 600 feet per second during their downfall, and thus they have the ability to inflict damage to multiple body cavities [4]. The larger caliber bullets (ie, .45-caliber) reach a higher terminal velocity compared with the smaller caliber bullets (ie, .30-caliber), because of the proportion of their weight to their diameter [4].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.annalsthoracicsurgery.org/article/S0003-4975(06)00831-9/abstract&quot; rel=&quot;noreferrer&quot;&gt;http://www.annalsthoracicsurgery.org/article/S0003-4975(06)00831-9/abstract&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For those hit by falling bullets, the chance of the wound being fatal was far higher than a typical shooting. The hospital put deaths from regular shootings between 2% and 6%, while for those struck by falling bullets the death rate was close to one third.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.theguardian.com/world/2011/aug/24/how-dangerous-is-celebratory-gunfire&quot; rel=&quot;noreferrer&quot;&gt;http://www.theguardian.com/world/2011/aug/24/how-dangerous-is-celebratory-gunfire&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Aircraft rounds&lt;/h2&gt;&#xA;&lt;p&gt;These falling bullets were from celebratory gunfire, not fired from aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Aircraft cannon fire projectiles which are often much heavier than handgun rounds. If one falls on you, the likelihood of injury or death must be higher.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xpUEF.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;img src=&quot;https://i.stack.imgur.com/uSb79.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;.22 Winchester magnum rimfire and .50 Browning MG rounds at same scale. &lt;a href=&quot;http://herohog.com/images/guns/ammo/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-09-26T11:08:52.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8766" PostTypeId="1" AcceptedAnswerId="8771" CreationDate="2014-09-26T10:21:02.863" Score="9" ViewCount="4157" Body="&lt;p&gt;What is the extra cost of aborted landing and go-around for typical &quot;big&quot; airliner?&lt;/p&gt;&#xA;" OwnerUserId="3660" LastEditorUserId="64" LastEditDate="2015-10-30T02:52:32.703" LastActivityDate="2016-05-06T04:38:06.913" Title="How much does go-around cost?" Tags="&lt;ground-operations&gt;&lt;go-around&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8767" PostTypeId="1" AcceptedAnswerId="8768" CreationDate="2014-09-26T12:31:50.153" Score="33" ViewCount="71368" Body="&lt;p&gt;I found on this website several questions speaking of &lt;a href=&quot;https://aviation.stackexchange.com/questions/8644/are-there-any-airports-that-do-not-have-an-iata-code-but-have-a-huge-number-of-t&quot;&gt;IATA&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1210/what-is-the-difference-between-icao-jaa-faa-easa-and-caa?&quot;&gt;ICAO&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/2644/can-two-airports-have-a-different-icao-code-but-share-the-same-iata-code/&quot;&gt;airports codes&lt;/a&gt;. The fact that two identification codes for the same airport exist means there are cases where you use one, and other cases where you use the other. I wonder what is the rule to know which code (IATA or ICAO) should be used. &lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2020-06-28T01:18:26.087" Title="When do we use IATA codes and when do we use ICAO codes?" Tags="&lt;icao&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8768" PostTypeId="2" ParentId="8767" CreationDate="2014-09-26T13:27:40.587" Score="28" Body="&lt;p&gt;It helps to know the objective of both ICAO and IATA to understand when which code is used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/about-icao/Pages/default.aspx&quot;&gt;ICAO&lt;/a&gt; (International Civil Aviation Organization) is a UN-body which focusses on international harmonization of civil aviation regulations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO codes are used for &quot;official&quot; purposes such as Air Traffic Control; E.g. flight plans use ICAO codes for airports and airline flight identification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.iata.org/Pages/default.aspx&quot;&gt;IATA&lt;/a&gt; (International Air Transport Association) is a trade association that focusses on making air traffic businesses safe, secure, reliable and efficient. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;IATA codes are mainly used for ticketing. E.g. travel itineraries use IATA codes for airports and IATA flight numbers. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-13T18:12:30.290" LastActivityDate="2014-10-13T18:12:30.290" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8769" PostTypeId="2" ParentId="8434" CreationDate="2014-09-26T14:55:34.987" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://blackswan.ch/nat/&quot; rel=&quot;noreferrer&quot;&gt;This guy&lt;/a&gt; has a 365 day history online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could contact him for older values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also get &lt;a href=&quot;https://web.archive.org/web/20140828071417/https://www.notams.faa.gov/common/nat.html&quot; rel=&quot;noreferrer&quot;&gt;some history&lt;/a&gt; using Archive.org.&lt;/p&gt;&#xA;" OwnerUserId="3662" LastEditorUserId="97" LastEditDate="2015-05-03T00:57:47.803" LastActivityDate="2015-05-03T00:57:47.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8770" PostTypeId="2" ParentId="8758" CreationDate="2014-09-26T15:44:19.427" Score="2" Body="&lt;p&gt;First, a clarification. The standard reference frame for and aircraft, w.r.t. a person sitting in the pilot seat, is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;x axis positive ahead of the aircraft&lt;/li&gt;&#xA;&lt;li&gt;y axis positive in the right wing direction&lt;/li&gt;&#xA;&lt;li&gt;z axis positive towards down&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In addition, to be clear about the conventions used in the rest of this answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;positive roll is when the right wing is down&lt;/li&gt;&#xA;&lt;li&gt;positive sideslip &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt; is when the pilot sees the air coming from the right side.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And, for completeness, &lt;span class=&quot;math-container&quot;&gt;$C_{N_p}$&lt;/span&gt; is the aerodynamic derivative of yaw rate &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt; (not &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt;) as function of roll rate &lt;span class=&quot;math-container&quot;&gt;$p$&lt;/span&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While &lt;span class=&quot;math-container&quot;&gt;$C_{N_q}$&lt;/span&gt; would be the one due to pitch rate &lt;span class=&quot;math-container&quot;&gt;$q$&lt;/span&gt;, but that would not be within your specified range of &lt;code&gt;conventional aircraft&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now to your question.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;when the aircraft starts rolling, will the aircraft experience sideslip and if yes in which direction (and most of all why) ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR version:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, it experiences sidelip and for positive roll rate &lt;span class=&quot;math-container&quot;&gt;$p$&lt;/span&gt; the sideslip &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt; will be negative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Extended version:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Positive roll rate means that the right wing is rotating down and the left wing up.&lt;/li&gt;&#xA;&lt;li&gt;This translates in a momentarily higher Angle of Attack &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; seen by the right wing w.r.t. the left wing&lt;/li&gt;&#xA;&lt;li&gt;Because of this difference in &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; seen by the wings, the right wing will produce slightly more lift (and this is the direct cause of the Roll Subsidance)&lt;/li&gt;&#xA;&lt;li&gt;Nevertheless, aileron deflection will make the left wing produce significantly more lift&lt;/li&gt;&#xA;&lt;li&gt;More lift means more induced drag&lt;/li&gt;&#xA;&lt;li&gt;More induced drag means that the left wing will tend to &quot;lag&quot; and the left wing will move ahead.&lt;/li&gt;&#xA;&lt;li&gt;The plane has thus rotated towards the left side, achieving a negative &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The amount of &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt; will obviously depend on the specific aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might find more by looking for information about the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dutch Roll&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2019-10-08T11:03:57.157" LastActivityDate="2019-10-08T11:03:57.157" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="8771" PostTypeId="2" ParentId="8766" CreationDate="2014-09-26T16:02:26.497" Score="17" Body="&lt;p&gt;We can look at &lt;a href=&quot;http://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=297&amp;amp;DB_Short_Name=Air%20Carrier%20Financial&quot; rel=&quot;noreferrer&quot;&gt;financial data&lt;/a&gt; from airlines to estimate these figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to fuel, there will also the extra duty time for the crew, some delay in schedule, and extra flight time on the aircraft. The delay in schedule can be difficult to estimate, but other costs of operation can be estimated. A short flight would take 1.5 hours, and the go around might take 0.2 hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the financial data, an MD-83 might cost about &lt;strong&gt;6000 dollars/hour&lt;/strong&gt; to operate. This includes all direct operating expenses. This means that the regular flight would cost about &lt;strong&gt;9000 dollars&lt;/strong&gt; to operate, and &lt;strong&gt;a go around would cost about 1200 dollars&lt;/strong&gt;. Since a go around uses a lot of fuel, the figure may be a bit higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The figures for a Boeing 747-400 show about 15000 dollars/hour to operate, and a Boeing 777-200 about 12000 dollars/hour to operate. That would make an 8 hour flight 120,000 dollars and 96,000 dollars respectively, with go arounds costing &lt;strong&gt;3000&lt;/strong&gt; and &lt;strong&gt;2400 dollars&lt;/strong&gt; respectively. Obviously, for longer flights, the go around will cost less proportionally than for a shorter flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As DeltaLima mentioned, the cost of &lt;a href=&quot;http://en.wikipedia.org/wiki/FedEx_Express_Flight_80&quot; rel=&quot;noreferrer&quot;&gt;not doing a go around&lt;/a&gt; (which includes &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;noreferrer&quot;&gt;making this decision early enough&lt;/a&gt;) can be substantially higher. Loss of or even just damage to an aircraft will cost much more time and money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To see if these numbers make sense, &lt;a href=&quot;http://avherald.com/h?article=4369190c&quot; rel=&quot;noreferrer&quot;&gt;this report&lt;/a&gt; mentions that an empty MD-83 would need 1000 kg of fuel for a go around and new approach. It also mentions that a ferry flight from Paris Orly to Olbia, Italy, would normally require 6800 kg including reserves. If reserves are about 1600 kg, this would mean that the flight would use 5200 kg of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If jet fuel costs &lt;a href=&quot;http://www.transtats.bts.gov/fuel.asp&quot; rel=&quot;noreferrer&quot;&gt;3 dollars per gallon&lt;/a&gt;, this comes out to 985.72 dollars of fuel for a go around, and 5125.73 dollars of fuel for a regular flight. This figure seems reasonable along with the figures above.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="3386" LastEditDate="2016-05-06T04:38:06.913" LastActivityDate="2016-05-06T04:38:06.913" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8772" PostTypeId="1" CreationDate="2014-09-26T16:24:13.137" Score="2" ViewCount="672" Body="&lt;p&gt;MH370 was flying at 11 km altitude at a speed of 872 km/h. It is known that some birds can fly at this altitude, e.g. the &lt;a href=&quot;https://en.wikipedia.org/wiki/R%C3%BCppell%27s_vulture&quot; rel=&quot;nofollow&quot;&gt;Rüppell's vulture&lt;/a&gt;. So, could such a bird hitting the windscreen at roughly 900 km/h cause cracks that would lead to decompression? And would such a scenario fit the known facts about MH370?&lt;/p&gt;&#xA;" OwnerUserId="2879" LastEditorUserId="22550" LastEditDate="2018-11-22T02:27:02.303" LastActivityDate="2018-11-22T02:27:02.303" Title="Could flight MH370 have suffered decompression due to a high altitude bird strike?" Tags="&lt;safety&gt;&lt;mh370-incident&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2014-09-29T04:34:22.207" ContentLicense="CC BY-SA 3.0" />
  <row Id="8773" PostTypeId="2" ParentId="8772" CreationDate="2014-09-26T16:56:33.400" Score="3" Body="&lt;p&gt;Based on this &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_birds_by_flight_heights&quot; rel=&quot;nofollow&quot;&gt;list of high-flying birds&lt;/a&gt;, there are only two that seem to have any possibility of being present in the area at that altitude at the time. These are the &lt;a href=&quot;http://en.wikipedia.org/wiki/Common_crane&quot; rel=&quot;nofollow&quot;&gt;common crane&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Bar-headed_goose&quot; rel=&quot;nofollow&quot;&gt;bar-headed goose&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.25_1775&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;The regulations on airliner windscreens&lt;/a&gt; say that they must not let a 4 lb bird penetrate at cruise speed at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The common crane weighs 10 lb on average, and the bar-headed goose 5.5 lb on average.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that the plane could encounter a bird over twice as heavy as designed for, at airspeeds almost twice as much as designed for. This could certainly cause the windsheild to fail, resulting in decompression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft windshield &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_5390&quot; rel=&quot;nofollow&quot;&gt;has failed at altitude before&lt;/a&gt;, though for a different reason. Despite sucking one pilot partially out of the cockpit, the remaining pilot was able to land the aircraft safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In conclusion, it is possible, but from experience highly unlikely, that the aircraft hit a bird at cruise altitude. If a bird penetrated the windshield (or even the nose), it could have damaged controls in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, it could also have been a meteor. But events like this are so unlikely that they are really not considered unless there is more evidence to support them. So we will have to wait and see what is found.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering how unlikely this scenario is, there are two possibilities here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bird caused the initial deviations. Maybe the bird knocked out communications, but the pilots were able to maintain partial control, explaining the further deviations. It's unclear why they would climb back up to cruise altitude unpressurized though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bird caused the final loss. The flight deviated as observed for unknown reasons, and started cruising south. At some point between there and fuel exhaustion, it hit the bird, resulting in loss of control.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-26T22:10:37.213" LastActivityDate="2014-09-26T22:10:37.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8774" PostTypeId="2" ParentId="3397" CreationDate="2014-09-26T19:20:13.687" Score="0" Body="&lt;p&gt;I just passed my PPL checkride a couple of weeks ago, and the examiner asked me this very question.  I said I'd have to look it up in the FAR, but as I started flipping pages he said don't bother... 3 full stop night landings do satisfy the requirements for day currency.&lt;/p&gt;&#xA;" OwnerUserId="3666" LastActivityDate="2014-09-26T19:20:13.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8776" PostTypeId="2" ParentId="8772" CreationDate="2014-09-26T20:43:11.613" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;would such a scenario fit the known facts about MH370?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The evidence presented by the team searching for the aircraft includes&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No voice communications using any of multiple radio systems available to cockpit crew.&lt;/li&gt;&#xA;&lt;li&gt;Transponder ceased responding to secondary radar.&lt;/li&gt;&#xA;&lt;li&gt;ADS-B transmissions ceased.&lt;/li&gt;&#xA;&lt;li&gt;ACARS transmission ceased.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft made a change of course back across Malaysia&lt;/li&gt;&#xA;&lt;li&gt;Malaysian military tracked an aircraft believed to be MH370 apparently following waypoints in the Malacca straights (suggesting another change of course)&lt;/li&gt;&#xA;&lt;li&gt;Satellite data appears to show MH370 then flying to the south for many hours on autopilot until it ran out of fuel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It isn't clear how a bird strike could disable the pilots and also cause the failure of all automated communication systems whilst allowing the autopilot (presumably) to make several turns and then fly the aircraft into the southern Indian ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;People have advanced many ideas about MH370. It isn't immediately obvious that this idea fits what is known any better than many of the other ideas.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="19" LastEditDate="2014-09-27T01:29:32.400" LastActivityDate="2014-09-27T01:29:32.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8777" PostTypeId="2" ParentId="8758" CreationDate="2014-09-26T22:04:19.923" Score="4" Body="&lt;p&gt;&lt;strong&gt;To answer what you wrote:&lt;/strong&gt; $c_{n_q}$ is the yawing moment induced by a pitching motion. In a conventional, symmetric configuration this is zero for the airframe and has a small value for propeller aircraft, depending on the rotation direction of the propeller. If the tractor propeller is spinning clockwise (when seen by the pilot), a positive pitch motion $q$ (nose up) will cause a small negative sideslip angle $\beta$. A positive pitch acceleration will add a precession moment which similarly pulls the aircraft's nose to the right. But I think you want to know something else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To answer what you meant:&lt;/strong&gt; $c_{n_p}$ is the yawing moment induced by a rolling motion. The axis system you propose (with z pointing up) is used to measure relative positions within the airframe, but for flight mechanics we prefer to put the x-axis in flight direction, y to the right and z down. A positive rolling motion $p = \omega_x\cdot\frac{b}{2\cdot v_{\infty}}$ (or $p = \omega_x\cdot\frac{b}{v_{\infty}}$, both definitions are used) is right-wing-down, and a positive yawing moment means the aircraft's nose moves to the right, causing negative side slip angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a positive rolling motion happens in still air, the resulting yawing moment is negative, pulling the aircraft's nose left, as Federico said. Thus, $c_{n_p}$ is negative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the reason is different: When the pilot deflects the ailerons and causes a difference in lift on the left and right wings, and consequently a difference in induced drag, the yawing moment caused by that difference in induced drag is called $c_{n_\xi}$, the yawing moment due to aileron deflection. $c_{n_\xi}$ is positive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft is in a steady roll, the roll damping $c_{l_p}$ will fully compensate the differential lift caused by aileron deflection. Now the rolling motion will increase the local angle of attack on the downward moving wing the farther you are away from the center, and decrease it on the upward moving wing. Since lift is perpendicular to local airflow, the air force vector on the downward moving wing is pointing slightly forward, and that on the upward moving wing slightly backwards. Please note that the total lift produced by each wing is roughly the same! The rolling moment of both is exactly zero once the roll rate is steady. However, the aileron deflection will decrease lift on the downward moving wing such that it just compensates for the increased angle of attack due to the rolling motion, and the same holds for the upward moving wing with its trailing-edge-down aileron deflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What &lt;strong&gt;is&lt;/strong&gt; different is not the magnitude, but the direction of lift on both wings. This pulls the downward-moving wing forward and the upward moving wing back, causing a negative yawing moment in a positive rolling motion. &lt;strong&gt;That&lt;/strong&gt; is why your conventional $c_{n_p}$ is negative.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-09-27T17:25:52.713" LastActivityDate="2014-09-27T17:25:52.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8778" PostTypeId="2" ParentId="8715" CreationDate="2014-09-26T23:43:39.497" Score="0" Body="&lt;p&gt;Actually I think they don´t have any plans for a stretched version of A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tim Clark, CEO of Emirates, wants a larger A380 but Airbus said (last time when this topic came up) that they would rather improve the current A380 and increase the performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are making a change by increase the lower floor height to add extra seat in each row&#xA;on economy but thats it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now Tim Clark is pressuring to make a neo-version af A380 and and Airbus is considering&#xA;that option. Emirates say that they would order up to 70 A380neo if that plane will be launched but Airbus has to calculate the cost and if it´s will be profitable for them.&lt;/p&gt;&#xA;" OwnerUserId="3663" LastActivityDate="2014-09-26T23:43:39.497" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8779" PostTypeId="1" AcceptedAnswerId="8782" CreationDate="2014-09-27T00:44:37.253" Score="8" ViewCount="3349" Body="&lt;p&gt;I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to &quot;squawk 7700.&quot; Presumably you're not just making bird noises with your mouth, but some sort of radio code. Are these the same radio system? What radio communication systems are modern big jets equipped with?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="15982" LastEditDate="2017-06-01T10:51:30.093" LastActivityDate="2017-06-01T10:51:30.093" Title="What radios are airliners / large aircraft equipped with?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;radio&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8780" PostTypeId="2" ParentId="8779" CreationDate="2014-09-27T02:42:53.633" Score="0" Body="&lt;p&gt;This depends on the plane - some planes don't have radios at all!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Squawking&quot; in this sense refers to punching a number into your transponder: &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Transponder_(aeronautics)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some squawk codes on that page if you want to read more!&lt;/p&gt;&#xA;" OwnerDisplayName="user1037" LastActivityDate="2014-09-27T02:42:53.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8781" PostTypeId="1" AcceptedAnswerId="8807" CreationDate="2014-09-27T02:59:26.580" Score="16" ViewCount="4879" Body="&lt;p&gt;The uncontrolled airfield where I have my airplane gets foggy in the morning occasionally, but there have been times when there is just a little fog where the AWOS station sits so it reports 1/4 mile visibility and undetermined ceiling, yet the runway farthest from it is clear and there are no clouds. My flight instructor and ground school instructor said you must always comply with the AWOS reported conditions, yet my flight examiner (I just got my private pilot license) said a pilot can overrule the automated station if it is clearly wrong. Machines can break and are limited to where their position is.&#xA;FAR 91.155 talks about visibility, but doesn't mention how it is determined. Flight visibility is determined by the pilot, so I interpret this to mean he can overrule the AWOS if it is clearly wrong.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(d) Except as provided in §91.157 of this part, no person may take off or land an aircraft, or enter the traffic pattern of an airport, under VFR, within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport—&lt;/p&gt;&#xA;&lt;p&gt;(1) Unless ground visibility at that airport is at least 3 statute miles; or&lt;/p&gt;&#xA;&lt;p&gt;(2) If ground visibility is not reported at that airport, unless flight visibility during landing or takeoff, or while operating in the traffic pattern is at least 3 statute miles.&lt;/p&gt;&#xA;&lt;p&gt;(e) For the purpose of this section, an aircraft operating at the base altitude of a Class E airspace area is considered to be within the airspace directly below that area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Another question about (e), after reading it about 5 times: my airport is class G up to 700 feet, then turns into class E above that. Does (e) mean that if I am at 700 feet AGL, I am still in class G? Of what significance is this?&lt;/p&gt;&#xA;" OwnerUserId="3670" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-03T20:23:38.013" Title="If AWOS reports IFR conditions but I can see at least three miles, can I take off or land?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8782" PostTypeId="2" ParentId="8779" CreationDate="2014-09-27T05:35:25.860" Score="16" Body="&lt;p&gt;Numbering the radios that I can think of offhand in the old 747-100 and -200 aircraft that I used to fly produces:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;2 VHF voice communications radios.&lt;/li&gt;&#xA;&lt;li&gt;2 VHF navigation radio receivers for receiving VOR and LOC signals. The LOC frequencies are paired with UHF frequencies for receiving glideslope signals.&lt;/li&gt;&#xA;&lt;li&gt;1 ADF (automatic direction finding) receiver.&lt;/li&gt;&#xA;&lt;li&gt;1 HF (high frequency) voice communication radio.&lt;/li&gt;&#xA;&lt;li&gt;2 transponders to send whatever the &quot;squawk&quot; is when interrogated. #1 was used on odd days of the month, #2 on even days. There are a number of standard codes, but ATC assigns a 4-digit code to each aircraft during flight under their control. There is never an 8 or a 9 in the code because it's an octal code.&lt;/li&gt;&#xA;&lt;li&gt;1 SELCAL (selective calling) receiver, which will sound an alert if it receives a signal sent by a ground station. It may not be a separate radio but just a box listening for a tone on one of the voice communication radios. &lt;/li&gt;&#xA;&lt;li&gt;1 weather radar, and, yes, radar is a radio (radio detection and ranging) employing both a transmitter and a receiver.&lt;/li&gt;&#xA;&lt;li&gt;1 radar altimeter for use in the final stages of the landing approach. Some were &quot;talkers&quot; in that starting around 50 feet, they would announce your altitude in increments of 10 feet.&lt;/li&gt;&#xA;&lt;li&gt;1 GPWS (ground proximity warning system). I'm not sure whether it and the radar altimeter shared a box/circuitry/antenaes.&lt;/li&gt;&#xA;&lt;li&gt;1 GPS receiver, which we got only in the last few months before I retired in 1999&lt;/li&gt;&#xA;&lt;li&gt;1 ELT (emergency locator transmitter)&lt;/li&gt;&#xA;&lt;li&gt;life raft locator beacons. I can't remember how many life rafts there were.&lt;/li&gt;&#xA;&lt;li&gt;life raft voice communication on 121.5 and maybe 243.0.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I may not have remembered them all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern transport category aircraft would also have SATCOM. Military aircraft would have UHF voice communications and mission appropriate weaponry radios.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-09-30T16:56:16.690" LastActivityDate="2014-09-30T16:56:16.690" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8783" PostTypeId="1" AcceptedAnswerId="8785" CreationDate="2014-09-27T10:16:38.477" Score="5" ViewCount="1060" Body="&lt;p&gt;I heard of a A320 landing, no lights, both generators out, RAT deployed, and with only 28VDC(battery power),  made a successful landing. Is this possible?&lt;/p&gt;&#xA;" OwnerUserId="3671" LastEditorUserId="3380" LastEditDate="2014-09-27T15:25:50.900" LastActivityDate="2014-09-27T19:20:02.967" Title="What is the minimum power system required to fly a commercial aircraft?" Tags="&lt;emergency&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8784" PostTypeId="1" CreationDate="2014-09-27T10:32:21.370" Score="11" ViewCount="11049" Body="&lt;p&gt;I have read that civil pilots have stringent regulations regarding flight hours and hours of rest between flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about military pilots? Does it change between wartime and peacetime? Between type of aircraft (transport vs combat)? &lt;/p&gt;&#xA;" OwnerUserId="3672" LastEditorUserId="1696" LastEditDate="2018-04-28T18:24:44.833" LastActivityDate="2018-04-28T18:24:44.833" Title="Do military pilots have flight &amp; rest hours regulation?" Tags="&lt;faa-regulations&gt;&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8785" PostTypeId="2" ParentId="8783" CreationDate="2014-09-27T11:22:59.773" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I heard of a A320 landing, no lights, both generators out, RAT deployed ... , made a successful landing. Is this possible?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A United Airlines Airbus A320-200, registration N409UA performing flight UA-497 from New Orleans,LA to San Francisco,CA (USA) with 109 people on board, was in the initial climb when the crew reported smoke in the cockpit, levelled off at 5000 feet and returned to New Orleans. The crew reported before joining downwind that they had lost all instruments and requested to be talked down by ATC via Precision Approach Radar (PAR). The crew descended to 600 feet where they got visual contact with the water of Lake Pontchartrain and continued visually for a landing on runway 19 about 10 minutes after departure. During landing the aircraft blew both right hand main gear tyres, went left off the runway, stopped with all gear just off the paved surface north of the intersection with runway 10/28, and was evacuated via slides.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A number of passengers needed medical attention due to smoke inhalation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Post landing photos showed the RAM Air Turbine (RAT) deployed. Runway 01/19 was closed for about 10 hours.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The crew told passengers that they had lost all electronics and were flying on minimal backup systems, landing would occur overweight with minimal braking and minimal steering ability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://avherald.com/h?article=43a6bc08&quot; rel=&quot;nofollow&quot;&gt;http://avherald.com/h?article=43a6bc08&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Early on, NTSB investigators suspected a faulty fire-warning sensor in the cargo hold. And they tentatively concluded that the cockpit crew had skipped a portion of the pre-flight checklist then failed to restore power to some equipment, making it more difficult to carry out the emergency landing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.nola.com/traffic/index.ssf/2013/05/united_497_emergency_landing_i.html&quot; rel=&quot;nofollow&quot;&gt;http://www.nola.com/traffic/index.ssf/2013/05/united_497_emergency_landing_i.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it seems there was nothing wrong with the aircraft apart from a faulty smoke sensor. The crew missed this in their preflight checks, noticed it after take-off and then turned off all the electric generators (they were supposed to turn one back on according to the checklist - they didn't). Anyway, they landed the plane OK on emergency power from batteries and RAT.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;with only 28VDC(battery power)*&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the A320 the RAT supplies the ESS bus, not main buses 1 and 2. It powers both the AC ESS bus and the DC ESS bus through the ESS TR (transformer rectifier). So that's not just 28V DC but AC too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the interval after both main generators failing and APU being unavailable, I believe the DC batteries power the DC ESS bus until the RAT is deployed and providing power (which should happen automatically and quickly). So in this short interval there is only DC power on the DC ESS bus.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-09-27T19:20:02.967" LastActivityDate="2014-09-27T19:20:02.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8786" PostTypeId="1" AcceptedAnswerId="8788" CreationDate="2014-09-27T17:11:57.717" Score="17" ViewCount="13573" Body="&lt;p&gt;Here is a question that has been bothering me for a while. Do right-handed fighter pilots use their right hand to hold the control stick? &lt;strong&gt;And do left-handed fighter pilots use their left hand?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is it the other way around? Or do they maybe use both hands a lot of the time? It also brings up the question as to what the other hand is expected to do and which side of the cockpit the most common control buttons are on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is that since most people are right handed, they use their right hand. There's also triggers on the yoke so it seems all the more likely that the right hand is used for right-handers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking because you look at &lt;strong&gt;video games and their controllers&lt;/strong&gt;. They always use the &lt;strong&gt;left joystick&lt;/strong&gt; for moving the character. In the case of flight simulators, the &lt;strong&gt;left joystick&lt;/strong&gt; is used as the 'stick' or yoke. So you're pretty much left with no choice but to use your left thumb. Not saying this is awkward for video games, however, on those big joysticks for PC games, I remember I always used my right hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, let's ignore civil commercial piloting because those seem to usually use steering wheel type controls, not a traditional stick. Please let me know if you're a fighter pilot when you answer, because the triggers on the yoke have an effect on which hand you're most comfortable with.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1696" LastEditDate="2018-04-27T19:31:27.037" LastActivityDate="2020-12-05T16:31:41.277" Title="Which hand do fighter pilots use for the control stick?" Tags="&lt;military&gt;&lt;flight-controls&gt;&lt;fighter&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8788" PostTypeId="2" ParentId="8786" CreationDate="2014-09-27T20:12:57.867" Score="21" Body="&lt;p&gt;Most fighter pilots, regardless of their handedness, use their right hand to fly the stick, and their left hand to move the throttle(s)/PCL (Power Control Lever). This is just how most fighter cockpits are set up, with the power on the left side.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ylyWkl.jpg&quot; alt=&quot;Eurofighter Typhoon cockpit&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The sticks are also not really usable for a left hander because a few of the buttons would be inaccessible with a left hand on the stick. In some cases (like the F-16), the cockpit uses a &lt;em&gt;sidestick&lt;/em&gt; layout, with the stick on the edge of the cockpit, rather than in between the pilot's legs.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gJwofl.jpg&quot; alt=&quot;F-16 cockpit (note the sidestick on the right and the throttle on the left)&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;So no, &lt;strong&gt;it would not really be possible for left-handed pilots to fly with their left hand on the stick for long periods of time&lt;/strong&gt; (I will note, that if you need to select something on the right side, most will hold the stick lightly in their left hand for a brief second, actuate the item with their right hand, and then switch back) unless the entire cockpit were redesigned, which is just not worth it.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2020-12-05T16:31:41.277" LastActivityDate="2020-12-05T16:31:41.277" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8789" PostTypeId="2" ParentId="8784" CreationDate="2014-09-27T23:29:19.923" Score="18" Body="&lt;p&gt;Yes, they do. My experience is with the U.S. Air Force, so my answer will be from that perspective, but other air arms have similar regulations.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;USAF&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://static.e-publishing.af.mil/production/1/af_a3_5/publication/afi11-202v3/afi11-202v3.pdf&quot; rel=&quot;noreferrer&quot;&gt;11-202V3&lt;/a&gt;, Chapter 9, &lt;em&gt;Crew Rest, Fatigue Management and Flight Duty Limitations&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;9.4.3 Augmented Aircrew&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A basic aircrew supplemented by additional aircrew members to permit in-flight rest periods IAW paragraph 9.4.8. If the basic aircrew requires only one pilot and a second qualified pilot (includes pilots enrolled in an AETC formal aircrew&#xA;  training course) is designated an aircrew member to augment pilot duties, the crew can be considered augmented.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;9.4.6 Flight Duty Period&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FDP begins when an aircrew member reports for a mission, briefing, or other official duty and ends when engines are shut down at the end of the mission, mission leg, or a series of missions. FDP for UAS ends at final engine shut down, final in-flight handover briefing, or final crew swap, whichever occurs last.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Table 9.1&lt;/em&gt; (Maximum Flight Duty Period in hours by aircraft type)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/KuKYu.png&quot; alt=&quot;Maximum Flight Duty Period in hours by aircraft type&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;9.8 Crew Rest&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircrew require at least 10 continuous hours of restful activities (including an&#xA;  opportunity for at least 8 hours of uninterrupted sleep) during the 12 hours immediately prior to the FDP. To ensure individual accountability and mission reliability, crewmembers should be officially notified prior to entering a crew rest period. A crew rest period cannot begin until after the completion of official duties.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you can see from the chart that it depends on the type of aircraft, and the number of qualified pilots on board. But there are of course exceptions (e.g. the B-2 Spirit has been known to fly missions up to &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#Operational_history&quot; rel=&quot;noreferrer&quot;&gt;44.3 hours&lt;/a&gt;), especially in wartime. All Air Force flights' risk is determined prior to the mission, and in training things like crew rest are instant no-flys, but when the needs of the mission dictate, pilots may have to overfly when they are the only or best option, or when exceptional circumstances dictate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, from the Navy (I searched for other regulatory publications from other countries, but couldn't find any):&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;US Navy&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.netc.navy.mil/nascweb/sas/files/3710.7t_ch8.pdf&quot; rel=&quot;noreferrer&quot;&gt;OPNAVINST 3710.7T&lt;/a&gt; Chapter 8:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;8.3.2.1.2 Flight Crew&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ground time between flight operations should be sufficient to allow flight crew to eat and obtain at least 8 hours of uninterrupted rest. Flight crew should not be scheduled for continuous alert and/or flight duty (required awake) in excess of 18 hours. If it becomes necessary to exceed the 18-hour rule, 15 hours of continuous off-duty time shall be provided.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;8.3.2.2.a Flight Time&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Daily flight time should not normally exceed three flights or 6-1/2 total hours flight time for flight personnel of single-piloted aircraft. Individual flight time for flight personnel of other aircraft should not normally exceed 12 hours. The limitations assume an average requirement of 4 hours ground time for briefing and debriefing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-10-01T20:31:17.660" LastActivityDate="2014-10-01T20:31:17.660" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8790" PostTypeId="1" CreationDate="2014-09-28T04:25:22.197" Score="20" ViewCount="5398" Body="&lt;p&gt;I noticed KBFI's class delta overlaps SeaTac's bravo by 500 to 700 feet. Does anyone know which tower the overlapping airspace belongs to? Does it classify as Bravo airspace and do you need to hear the magic &quot;cleared into the bravo&quot; phrase before entering the overlapping areas? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: There is a tiny sliver of class D airspace surrounding the surface B of SeaTac on the western, southern and southeastern parts of the bravo that is surface. Anyone know if this belongs to SeaTac because there is no other field in the center of the area and if so, why on earth does a bravo airport also have a tiny section of class D surrounding it? &lt;/p&gt;&#xA;" OwnerUserId="3679" LastEditorUserId="34686" LastEditDate="2020-03-16T19:08:40.000" LastActivityDate="2020-03-17T21:36:32.537" Title="Why does Class D overlap class B around SeaTac? ...and other Seattle Bravo airspace strangeness" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;aeronautical-charts&gt;&lt;class-b-airspace&gt;&lt;class-d-airspace&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8791" PostTypeId="2" ParentId="8790" CreationDate="2014-09-28T04:53:30.650" Score="20" Body="&lt;p&gt;This is a great question. For those who are unfamiliar, and in areas where airspace is complex, it’s sometimes useful to look at the &lt;a href=&quot;http://skyvector.com/?ll=47.53415792556457,-122.30748618037265&amp;amp;chart=157&amp;amp;zoom=4&quot; rel=&quot;noreferrer&quot;&gt;VFR Flyway Chart&lt;/a&gt;. This is the one on the back of FAA Terminal Area Charts.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9OUd0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9OUd0.jpg&quot; alt=&quot;Seattle VFR Flyway Planning Chart&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The dashed blue outlines surround the crazy cutouts that are Seattle’s Class D airspaces.&lt;/p&gt;&#xA;&lt;h2&gt;Why does KBFI stick into the KSEA Class B?&lt;/h2&gt;&#xA;&lt;p&gt;Class D airports, or at least those that don’t exist entirely within more restrictive airspace, will always have a ceiling. This is because there will be sections that are &lt;em&gt;not&lt;/em&gt; contained within the Class B (or C) areas. For those areas, we need to know how high the Class D airspace goes.&lt;/p&gt;&#xA;&lt;h2&gt;If there is Class B and Class D airspace in the same place, which is it?&lt;/h2&gt;&#xA;&lt;p&gt;This one is in the AIM, 3-1-3:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;Hierarchy of Overlapping Airspace Designations&lt;/h3&gt;&#xA;&lt;p&gt;a. &lt;strong&gt;When overlapping airspace designations apply to the same airspace, the operating rules associated with the more restrictive airspace designation apply.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, if you’re over the I-90 bridge at 1900 feet, you’re in KBFI Class D. If you’re at 2100 feet, you’re in KSEA Class B.&lt;/p&gt;&#xA;&lt;h2&gt;Why does KSEA have weird class D chunks?&lt;/h2&gt;&#xA;&lt;p&gt;This one is easier - because Class B doesn’t always go to the surface (only at the core), but there is still a need to filter out traffic from the immediate airport environs. Because two-way communication is required, pilots will need to talk to the tower before getting too close (~5SM) to the airport.&lt;/p&gt;&#xA;&lt;p&gt;Another factor is that Class D centers on the airport; Class B is centered on the SEA VOR, and they are not coincident. This is so that the rings could (when it was circular) be defined with DME.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-28T00:30:53.923" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8793" PostTypeId="1" AcceptedAnswerId="8802" CreationDate="2014-09-28T14:32:26.633" Score="5" ViewCount="284" Body="&lt;p&gt;Currently USA has allowed phones to be used in commercial flights, is there a similar ruling coming to Europe or will my mid air Bluetooth battles have to wait? &lt;/p&gt;&#xA;" OwnerUserId="3314" LastEditorUserId="13197" LastEditDate="2016-04-26T14:17:56.817" LastActivityDate="2016-04-26T14:17:56.817" Title="When will Europe allow phones (to communicate) on planes?" Tags="&lt;commercial-aviation&gt;&lt;easa-regulations&gt;&lt;cell-phone&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8795" PostTypeId="1" AcceptedAnswerId="27773" CreationDate="2014-09-28T19:53:20.067" Score="5" ViewCount="1379" Body="&lt;p&gt;I was reading about &lt;a href=&quot;http://avherald.com/h?article=47acbff9&quot; rel=&quot;nofollow noreferrer&quot;&gt;this incident&lt;/a&gt; where a near miss occurred in class B airspace between IFR and VFR flights that were in contact with different controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I would like to know which controller normally gives the clearance to enter class B airspace to a VFR flight? When entering from class E, does the area controller provide the clearance or the approach controller of the airport whose class B it is? And is the flight then handed off to the appropriate approach controller? And when the aircraft then crosses from one class B airspace to another?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That particular incident happened &#xA;&lt;img src=&quot;https://i.stack.imgur.com/Ryrwu.png&quot; alt=&quot;cut from skyvector showing the location of the abovementioned incident&quot;&gt;&lt;br&gt;&#xA;at 4000 ft amsl. This chart does not list frequency for that airspace, but it is clearly airspace of the (Danish) Kobenhavn/Kastrup (EKCH) airport. But it is in Swedish airspace and Sweden area (ESAA). The VFR flight was flying from east to west, so must have crossed from other class B sector that apparently belongs to Malmo (ESMS) about 5 nm earlier. So does it make any sense it was (still) talking to Swedish controller (the article is not absolutely clear, but seems to say it was Sweden area, not Malmo approach) while the other flight was talking to Kobenhavn approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously I am not trying to find what happened; the investigation will hopefully eventually explain that. I'd just like to understand what the normal procedure in such situation is.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="62" LastEditDate="2014-09-29T16:44:02.263" LastActivityDate="2016-05-24T21:43:37.040" Title="Who controls VFR flights in class B airspace in Europe?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;easa-regulations&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8796" PostTypeId="2" ParentId="735" CreationDate="2014-09-28T19:59:03.117" Score="12" Body="&lt;p&gt;As others have pointed out, fitting the ring to the prop will greatly increase the stress on the blades. The same effect can be had with a nicely fitted shroud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has indeed been &lt;a href=&quot;http://en.wikipedia.org/wiki/RFB_Fantrainer&quot; rel=&quot;nofollow noreferrer&quot;&gt;a plane which used this concept&lt;/a&gt;, the RFB FanTrainer (see picture below). To reduce weight and wetted area, the prop diameter was much smaller than with a regular propeller, so the overall efficiency was not better. However, the smaller rotating inertias did produce a more turbine-like effect (less precession), so the concept was used for a basic trainer for future jet pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CY4UF.jpg&quot; alt=&quot;FanTrainer 400&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, the FanTrainer enjoyed only limited success and was discontinued after 50 had been built. The design was too lightweight to support all the desires of air forces for a basic trainer, and the private market at that time was shrinking and full of older planes which served the cost-conscious customers equally well. It did, however, offer almost jet-like characteristics for a uniquely low price per flight hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, if you want to shroud the propeller for better efficiency, you need to accept the higher surface area of the shroud, which will quickly add more drag than you are ever likely to save by preventing flow around the prop tips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What could be saved by shrouding the prop? Induced drag would be the same, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;since this comes from lift creation&lt;/a&gt;. The &lt;a href=&quot;http://webdoc.sub.gwdg.de/univerlag/2010/GKSM3.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;classical theory for minimum induced loss propellers by A. Betz and L. Prandtl&lt;/a&gt; requires an elliptic lift distribution over the propeller disc, such that lift smoothy tapers off at the tips. Artificially increasing it would only help if this could reduce blade chord at the tips - since the tips see the highest dynamic pressure, this could indeed translate into less friction drag. However, this gain is small when compared to the massive increase in friction drag of a shroud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high speeds the induced losses are small, and other factors become dominant. Note that turbofans and highly loaded propellers are not designed for minimum induced loss, but for maximum thrust with a given diameter. A shrouded propeller can enjoy a higher disc loading, so you get the same thrust with smaller blades and lower tip speeds, which will help in high speed efficiency. Smaller blades translate into less friction losses on the prop, and lower tip speeds translate into higher cruise speed before Mach losses begin to bite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, at high speed a shroud can be helpful when it is not too large. Turbofan engines suffer from this dilemma. They could have much higher bypass ratios than today, but this would mean huge nacelles, and the increased nacelle drag would offset the gains from the increased bypass ratio. Actively laminarising nacelle flow is the way forward here, but so far the practical implementation has yet to happen.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-12-17T07:26:55.870" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8797" PostTypeId="2" ParentId="716" CreationDate="2014-09-28T21:03:30.750" Score="15" Body="&lt;p&gt;Now I am going to commit a heresy, but keep reading to get an explanation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Increasing the aspect ratio of a wing will not change its induced drag. Increasing the span will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The induced drag coefficient of a wing is &lt;span class=&quot;math-container&quot;&gt;$c_{Di} = \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$&lt;/span&gt;, and this seems to indicate that a bigger aspect ratio AR would lower the induced drag coefficient &lt;span class=&quot;math-container&quot;&gt;$c_{Di}$&lt;/span&gt;. But only at the same lift coefficient &lt;span class=&quot;math-container&quot;&gt;$c_L$&lt;/span&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's look at the real numbers and compare two wings of the same span, but different aspect ratios. For simplicity, wing 1 has an AR of 5 and wing 2 has an AR of 10. Let's further assume that both wings have the same mass. Since both wings have the same span, wing 1 has twice the wing area of wing 2. To create the same lift, wing 1 needs only half the lift per area than wing 2! This means its &lt;span class=&quot;math-container&quot;&gt;$c_L$&lt;/span&gt; is only half as big as that of wing 2, and now lets look at the induced drag again: &lt;span class=&quot;math-container&quot;&gt;$D_i = q_\infty\cdot S\cdot c_{Di}$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing 1: &lt;span class=&quot;math-container&quot;&gt;$D_{i_1} = q_\infty\cdot S_1\cdot\frac{c_{L_1}^2}{\pi\cdot AR_1\cdot\epsilon}$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing 2: &lt;span class=&quot;math-container&quot;&gt;$D_{i_2} = q_\infty\cdot S_2\cdot\frac{c_{L_2}^2}{\pi\cdot AR_2\cdot\epsilon} = q_\infty\cdot 0.5\cdot S_1\cdot\frac{4\cdot c_{L_1}^2}{\pi\cdot 2\cdot AR_1\cdot\epsilon} = D_{i_1}$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both have the same span efficiency &lt;span class=&quot;math-container&quot;&gt;$\epsilon$&lt;/span&gt;, both have the same induced drag at the same lift. To reduce induced drag requires a span increase, regardless of aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a higher aspect ratio wing does have advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lower surface area means less friction drag&lt;/li&gt;&#xA;&lt;li&gt;Lower surface area also means less mass, at least at moderate aspect ratios.&lt;/li&gt;&#xA;&lt;li&gt;Smaller pitching moments, requiring a smaller tailplane&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;but also disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less internal volume for fuel or the landing gear&lt;/li&gt;&#xA;&lt;li&gt;Needs more complex high lift devices for the same landing speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the end, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;wing chord is chosen to minimize wing mass&lt;/a&gt; and to yield the minimum required fuel volume, and the aspect ratio is just a consequence of the selected wing span. Driving wing mass down is also reducing induced drag, and the &lt;span class=&quot;math-container&quot;&gt;$\epsilon$&lt;/span&gt; of modern airliner wings is only 0.75 to 0.8, which shows how little importance the induced drag coefficient has for finding an overall optimum.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-05-18T20:58:46.783" LastActivityDate="2019-05-18T20:58:46.783" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="8799" PostTypeId="2" ParentId="8781" CreationDate="2014-09-29T06:58:05.907" Score="2" Body="&lt;p&gt;According to AIM 5-5-1 paragraph b: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot-in-command of an aircraft is directly responsible for, and is the final authority as to the safe operation of that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;CFR Section 91.3(a) states: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot-in-command of an aircraft is directly responsible for, and&#xA;  is the final authority as to, the operation of that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You'll see this pattern throughout the FAR/AIM's. The regulations state what parameters you can operate under, but you're responsible for gathering data from METAR's, TAF's, ASOS and ATIS and other sources and making a decision on weather you are able to comply with VFR weather minima for the class of airspace you're in if you depart. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding your second question: The floor of E is at 700ft so that means if your altitude is 700ft AGL exactly you're still in E but you're subject to the weather minimums of whatever is below it which in your case is class G weather minimums. If the floor of the class E was on top of Bravo airspace, then if you're exactly on the floor you're subject to class B weather minimums. I think it's just anticipating the lawsuit that may arise from someone being exactly at 700ft and claiming they were in class E instead of whatever is below it with regards to weather minimums. &lt;/p&gt;&#xA;" OwnerUserId="3679" LastActivityDate="2014-09-29T06:58:05.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8800" PostTypeId="1" AcceptedAnswerId="8816" CreationDate="2014-09-29T07:04:35.120" Score="6" ViewCount="453" Body="&lt;p&gt;Today I was in a simulator on runway 20R at KSNA. ATC gave me a VFR clearance and told me to fly heading 080 on departure. The runway has right traffic. I turned right and was told by ATC I should have turned left because you're supposed to always take the shortest turn to assigned heading when given a heading, even if the runway has an opposite traffic pattern. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: Where does the FAR/AIM specify this rule? Are there any other legal publications that specify this? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus points if you can cite a reference to this rule in any PPL textbook e.g. Jeppesen's Guided Flight Discovery Private Pilot. Thanks.&lt;/p&gt;&#xA;" OwnerUserId="3679" LastEditorUserId="13197" LastEditDate="2016-04-26T22:08:23.273" LastActivityDate="2016-04-26T22:08:23.273" Title="Which FAR/AIM addresses Shortest Turn to Assigned Heading vs Runway Traffic Pattern?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;&lt;traffic-pattern&gt;&lt;clearance&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8801" PostTypeId="2" ParentId="8795" CreationDate="2014-09-29T07:23:16.380" Score="3" Body="&lt;p&gt;I'm assuming you're referring to this where a Cessna 172 had a near miss with a 737: &lt;a href=&quot;http://www.havarikommissionen.dk/~/media/Files/Havarikommissionen/Havarirapporter/Luftfart%202014/Preliminary%20ATI%20Bulletin%20HCLJ510_2014_273.ashx&quot; rel=&quot;nofollow&quot;&gt;http://www.havarikommissionen.dk/~/media/Files/Havarikommissionen/Havarirapporter/Luftfart%202014/Preliminary%20ATI%20Bulletin%20HCLJ510_2014_273.ashx&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding who the VFR pilot should have been talking to, that depends. For example if you're flying in Los Angeles you might get clearance into the bravo for LAX from SoCal Approach if you're taking the &quot;coastal route&quot; through the bravo, or you might get clearance from LAX tower if you're flying the lower altitude &quot;mini route&quot; which directly overfly's LAX runways and tower and you'd be talking to whoever you got clearance from until they handed you off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It really depends how they've set it up. The  terminal area chart (TAC chart) for the bravo airspace contains VFR flyways and procedures including who to contact for clearance. So if you're interested you can get the TAC chart for Kobenhavn and look (usually) on the back of the physical chart where it has more info. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, having said that: I think this VFR pilot accidentally flew into bravo airspace and will probably lose his/her license. Here's why: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot did not have a Mode C altitude reporting transponder which is REQUIRED to fly in to Bravo. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft B was reported to fly at 4000 feet with &lt;strong&gt;no radar presented altitude readout&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure how &quot;Sweden control&quot; hands off to Denmark, but if he's flying to bravo in Denmark you'd expect him to be talking to someone in Denmark, either the bravo airport's tower or Copenhagen Approach which is who the Boeing 737 involved in the incident was talking to. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If he was in Bravo legally he should have been assigned an altitude, heading and squawk code and ATC should have maintained separation between those two aircraft and the bravo controllers are the best in the world at doing exactly that. So I think he accidentally flew into bravo and was talking to the wrong controller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edited: To remove irrelevant detail about VFR altitudes above 3000ft AGL. &lt;/p&gt;&#xA;" OwnerUserId="3679" LastEditorUserId="3679" LastEditDate="2014-09-29T07:28:40.053" LastActivityDate="2014-09-29T07:28:40.053" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8802" PostTypeId="2" ParentId="8793" CreationDate="2014-09-29T08:21:56.330" Score="3" Body="&lt;p&gt;There is a similar ruling since last week. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of electronic equipment as long as they are in &quot;flight mode&quot; during all phases of flight was already allowed in Europe by EASA since &lt;a href=&quot;https://www.easa.europa.eu/newsroom-and-events/press-releases/easa-allows-use-electronic-devices-board&quot; rel=&quot;nofollow&quot;&gt;November 2013&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since last week (&lt;a href=&quot;https://www.easa.europa.eu/newsroom-and-events/press-releases/easa-allows-electronic-devices-remain-and-connected-throughout&quot; rel=&quot;nofollow&quot;&gt;26 November 2014&lt;/a&gt;) EASA also allows phones to be on and connected throughout the flight. This allows for WiFi services, phone services and Bluetooth battles during the flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before allowing the use of these electronics in flight, airlines have to assess the impact of the signals transmitted by the mobile devices on the aircraft, ensuring aircraft systems are not affected. For this reason mobile communication will not be allowed by all airlines on all flights at once. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-09-29T13:26:31.007" LastActivityDate="2014-09-29T13:26:31.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8803" PostTypeId="2" ParentId="8670" CreationDate="2014-09-29T12:11:07.640" Score="3" Body="&lt;p&gt;There is no &quot;best&quot; overall, eternal, number. Any question asking for a mythical &quot;best&quot; anything can't ever come up with a specific answer as none exists.&lt;br/&gt;&lt;br/&gt;&#xA;The best undercariage configuration is that configuration which most effectively takes the weight of the aircraft and distributes it to the ground without overloading the surfaces it's moving over.&lt;br/&gt;&#xA;And THAT will depend highly on not just the size, shape, and weight of the aircraft, but the operational characteristics, landing and takeoff speeds, etc. etc. etc.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-09-29T12:11:07.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8804" PostTypeId="2" ParentId="8790" CreationDate="2014-09-29T14:19:23.647" Score="3" Body="&lt;p&gt;The SeaTac Class D space is below the SeaTac Bravo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its purpose is basically that if you are getting close to the Bravo, SeaTac wants to be in communication with you, and know that you're aware of your proximity to the Bravo. But they probably won't issue you a Transponder Code or give you vectors (unless traffic is near by).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its just gives them confidence that you're aware of where you are and what you're doing before you end up in front a 767 on short-final. :)&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-09-29T14:19:23.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8805" PostTypeId="1" AcceptedAnswerId="8806" CreationDate="2014-09-29T14:22:22.170" Score="20" ViewCount="5651" Body="&lt;p&gt;On this &lt;a href=&quot;http://en.wikipedia.org/wiki/Tenzing-Hillary_Airport&quot;&gt;airport&lt;/a&gt;, it seems the &lt;a href=&quot;http://www.airliners.net/photo/Yeti-Airlines/De-Havilland-Canada/0197484/&amp;amp;sid=2845828de5a355507bb40bac96e7f23d&quot;&gt;runway end with a wall followed by a mountains&lt;/a&gt;. Thus the pilots physically can't overrun the runway and if they decide to interrupt the landing, the go-around maneuver seems to include a very tight turn to avoid the mountain unless performed very soon during the approach. Is it possible to perform a go-around, and a which point it becomes impossible for this particular airport?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="65" LastEditDate="2014-09-29T14:31:09.543" LastActivityDate="2020-04-07T22:47:26.927" Title="Is it possible to go-around at Lukla Airport?" Tags="&lt;airport&gt;&lt;go-around&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8806" PostTypeId="2" ParentId="8805" CreationDate="2014-09-29T14:52:06.403" Score="18" Body="&lt;p&gt;&lt;strong&gt;No, it is almost impossible.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only runway (06/24) Lukla Airport is just 1500 feet long. This &lt;a href=&quot;http://travel-safety.knoji.com/interesting-facts-on-lukla-airport-the-most-dangerous-airport-in-the-world/&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt; lists some interesting facts:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The topography of the place makes any go-around impossible. At the&#xA;  south, the runway is the end of an angled drop of about 2000 feet.&#xA;  This cliff is fenced off as a precautionary measure. At the northern&#xA;  end of the runway there is a huge mountain terrain. It leaves no room&#xA;  for error.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A pilot mentions the same &lt;a href=&quot;http://www.weather.com/travel/mount-everest-airport-will-terrify-you-photos-20130618&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Because there is no way to go around again, we have to calculate many&#xA;  things like air speed, tail wind, fog. If you don't do the proper&#xA;  calculation or proper exercise, then it (an accident) happens.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Planes land on runway 06 (Heading 060 or ENE) and takeoff from runway 24 (Heading 240 or WSW). This picture shows the cliff on North:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Yx9m0.jpg&quot; alt=&quot;Lukla Airport from air&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been several &lt;a href=&quot;http://en.wikipedia.org/wiki/Tenzing-Hillary_Airport#Incidents_and_accidents&quot; rel=&quot;noreferrer&quot;&gt;accidents&lt;/a&gt; at this airport.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="14957" LastEditDate="2017-07-11T06:19:12.497" LastActivityDate="2017-07-11T06:19:12.497" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8807" PostTypeId="2" ParentId="8781" CreationDate="2014-09-29T14:58:25.287" Score="10" Body="&lt;p&gt;In the specific case that you mentioned (VFR at an uncontrolled field), you can take off or land because the only legal requirement is to maintain VFR cloud clearance and it's your responsibility at the pilot to do that. The possible downside would be that if you have some kind of accident or incident and the FAA or NTSB investigates, they will take the AWOS reports as the reference for weather conditions at the time. If weather or visibility was relevant to the accident then your decision might be questioned, unless of course there are witnesses who can confirm the actual conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a controlled field and VFR, ATC will base their actions on the reported conditions so they would tell you that the field is IFR only. One 'workaround' that could be useful is an SVFR clearance, which allows you to operate VFR in an airport surface area even below VFR minimums. You have to request it because ATC can't offer it although they may hint strongly at it to help you out: &quot;the field is IFR, is there anything you'd like to request?&quot; But ATC &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/FSS/fss0405.html&quot;&gt;may not issue an SVFR clearance if the reported visibility is below 1 mile&lt;/a&gt;, so in the scenario you mentioned it wouldn't help you. (And note that you need an instrument rating for SVFR at night.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under IFR the picture is different. A part 91 IFR flight can legally depart in zero visibility so there would be no issue there, provided that you get your clearance on the ground first, before entering IMC. Legal in this case obviously isn't the same thing as safe, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I deliberately didn't answer your second question because I think it would be best for you to submit it as a separate question.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-09-29T14:58:25.287" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8808" PostTypeId="2" ParentId="8779" CreationDate="2014-09-29T16:29:41.370" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.b737.org.uk/communications.htm&quot; rel=&quot;nofollow&quot;&gt;This site&lt;/a&gt; has good information about the various radios on the 737 classic vs. NG, which will be similar to other modern airliners (though locations may differ somewhat). The graphics at the bottom show the external antennas, which include (for the NG):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Glide Slope - for ILS guidance&lt;/li&gt;&#xA;&lt;li&gt;Localizer - for ILS guidance&lt;/li&gt;&#xA;&lt;li&gt;Weather Radar&lt;/li&gt;&#xA;&lt;li&gt;GPS&lt;/li&gt;&#xA;&lt;li&gt;Radio Altimeter&lt;/li&gt;&#xA;&lt;li&gt;ADF 1 - Navigation&lt;/li&gt;&#xA;&lt;li&gt;ADF 2&lt;/li&gt;&#xA;&lt;li&gt;Marker Beacon - for approach guidance&lt;/li&gt;&#xA;&lt;li&gt;DME - Navigation&lt;/li&gt;&#xA;&lt;li&gt;VOR - Navigation&lt;/li&gt;&#xA;&lt;li&gt;TCAS x2&lt;/li&gt;&#xA;&lt;li&gt;ATC 1 - Maybe transponder, ACARS&lt;/li&gt;&#xA;&lt;li&gt;ATC 2&lt;/li&gt;&#xA;&lt;li&gt;VHF 1 - Regular voice communication&lt;/li&gt;&#xA;&lt;li&gt;VHF 2&lt;/li&gt;&#xA;&lt;li&gt;HF - For long range voice communication, such as oceanic crossings&lt;/li&gt;&#xA;&lt;li&gt;ELT - Emergency Locator Transmittor&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Please note that the above location diagrams are only a guide as the antenna fitted depends upon the customer avionics options. Eg some NG's do not have ADF but do have SATCOM or IFTS/Airphone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More and more planes have satellite antennas for in-flight internet access, too. Military planes will also include more antennas for things like UHF and SATCOM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ab9il.net/aviation/737-radio.html&quot; rel=&quot;nofollow&quot;&gt;Another site&lt;/a&gt; offers some details about certain radios on the 737 NG, including the power each one uses:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;HF Voice Transceiver        400W&#xA;VHF Voice Transceiver       25W&#xA;DME (962 to 1150 MHz Xmit)  316W&#xA;Radar Altimeter (4300 MHz)  400mW&#xA;TCAS                        400W&#xA;Transponder (1090 MHz)      631W&#xA;WX Radar (9.3 Ghz)          120W &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;For instance, it's interesting how the HF radio uses much more power than the VHF radio, and that the transponder uses the most power on the list.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-09-29T16:37:56.507" LastActivityDate="2014-09-29T16:37:56.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8809" PostTypeId="1" AcceptedAnswerId="8823" CreationDate="2014-09-29T16:45:58.490" Score="26" ViewCount="2446" Body="&lt;p&gt;Lufthansa's pilot union is calling for a strike to defend pilot's right to retire at the age of 55. They argue that the stressful job of flying is too much for older people. This provokes two questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What fraction of pilots takes advantage of such a rule (if it is available to them)?&lt;/li&gt;&#xA;&lt;li&gt;Is there really a steep decline in the capabilities of older pilots?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I would expect that many pilots continue to fly, so I wonder whether it makes sense for Lufthansa to risk full confrontation. Also, if the reasoning of the union is right, it would be prudent for airlines to retire older pilots before they are a safety risk.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-08-23T06:15:09.693" LastActivityDate="2018-08-23T06:15:09.693" Title="Are airline pilots worn out at an age of 55?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8810" PostTypeId="1" AcceptedAnswerId="8811" CreationDate="2014-09-29T18:04:25.790" Score="9" ViewCount="737" Body="&lt;p&gt;I have my SEL Private VFR licence.  I recently went on a glider flight, and I loved it.  How much extra work does it take a typical pilot to transition from SEL to gliders?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What extra material will I have to learn?  And what overlaps? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="62" LastEditDate="2014-09-29T20:00:57.473" LastActivityDate="2014-09-29T20:00:57.473" Title="How much extra work to get a glider licence?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;glider&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8811" PostTypeId="2" ParentId="8810" CreationDate="2014-09-29T18:36:28.640" Score="10" Body="&lt;p&gt;(I am assuming your question is asking about the FAA regulations.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you already have a PPL, then the requirements are modest. According to the &lt;a href=&quot;http://www.ssa.org/GliderPilotRatings&quot;&gt;Soaring Society of America&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Additional Pilot Rating&lt;/strong&gt;&lt;br&gt;&#xA;  Holders of a valid FAA Power plane license with 40 hours as pilot-in-command need a minimum of 10 solo flights to qualify to take the glider flight test. No written exam is required to add a glider rating to a power license. In all cases, refer to the Federal Aviation Regulations for details on pilot licensing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-09-29T18:36:28.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8812" PostTypeId="1" AcceptedAnswerId="8814" CreationDate="2014-09-29T19:22:52.487" Score="22" ViewCount="33701" Body="&lt;p&gt;A nearby airport has a single 05/23 runway (3900m long), where airplanes start and land in one direction during certain periods and in the opposite direction during other periods. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is the direction determined -- I assume it's air traffic control which decides that but based on what ? (wind, sun ?)&lt;/p&gt;&#xA;" OwnerUserId="3632" LastActivityDate="2017-09-26T20:50:43.550" Title="What determines in which direction a runway is used?" Tags="&lt;runways&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8813" PostTypeId="2" ParentId="8812" CreationDate="2014-09-29T19:26:29.387" Score="10" Body="&lt;p&gt;Runway in use is based on wind, most of the time, with aircraft taking off into the wind. In some cases, when the wind is calm, airports have a default runway (it usually has better lighting, or approach systems for aircraft to use during conditions with poor visibility).&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2014-09-29T19:26:29.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8814" PostTypeId="2" ParentId="8812" CreationDate="2014-09-29T19:26:46.800" Score="22" Body="&lt;p&gt;Wind direction mostly, planes take off best when facing in the wind as that means free airspeed so the takeoff roll is shorter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In busier airspace (with multiple towered airports) each airport coordinates the corridors so they don't intersect depending on available runways, prevailing winds and relative demands on the airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible that it is dictated by noise abatement measures so night time flights pass over a nearby forest rather than wake up the capital.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-09-29T21:58:42.330" LastActivityDate="2014-09-29T21:58:42.330" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8815" PostTypeId="2" ParentId="8812" CreationDate="2014-09-29T19:37:48.450" Score="26" Body="&lt;p&gt;There are several factors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Prevailing winds&lt;/li&gt;&#xA;&lt;li&gt;Neighboring airport traffic patterns&lt;/li&gt;&#xA;&lt;li&gt;Size of inbound aircraft&lt;/li&gt;&#xA;&lt;li&gt;Where the aircraft is coming from&lt;/li&gt;&#xA;&lt;li&gt;Final parking space&lt;/li&gt;&#xA;&lt;li&gt;Congestion&lt;/li&gt;&#xA;&lt;li&gt;Fuel status&lt;/li&gt;&#xA;&lt;li&gt;Weather (thunderstorms)&lt;/li&gt;&#xA;&lt;li&gt;Noise considerations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At small airports, it is usually just the runway that faces into the wind and can accommodate most of the traffic coming in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At large airports, the wind dictates which flow is being used (like a &quot;north flow&quot; or &quot;south flow&quot;). From there, aircraft usually are assigned to land on which ever side of the airport their arrival procedure brings them to. Sometimes, it is also decided by which gate/terminal they'll be parking at. Lastly, the available approach procedures can change things if the weather is not good&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-09-29T19:37:48.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8816" PostTypeId="2" ParentId="8800" CreationDate="2014-09-29T20:21:18.197" Score="8" Body="&lt;p&gt;The most important point is that if any ATC instruction isn't clear then you should just ask them to repeat or clarify it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, turning in the shorter direction is &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/F.HTM&quot;&gt;stated&lt;/a&gt; in the FAA's &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/pcg/index.htm&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FLY HEADING (DEGREES)- Informs the pilot of the heading he/she should&#xA;  fly. The pilot may have to turn to, or continue on, a specific compass&#xA;  direction in order to comply with the instructions. The pilot is&#xA;  expected to turn in the shorter direction to the heading unless&#xA;  otherwise instructed by ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In my personal experience, ATC almost always say left or right for heading changes if you're on an approach or departure, but sometimes leave it out if you're in cruise. That makes sense to me: the busier the airspace the more they want to make sure that you don't turn the wrong way.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-09-29T20:21:18.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8817" PostTypeId="1" CreationDate="2014-09-29T20:32:42.013" Score="10" ViewCount="2427" Body="&lt;p&gt;Has there ever been any aircraft of any type that could glide safely with no control input simply based on the way the frame of the aircraft was designed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was trying to think of requirements for building an aircraft that would be accessible to the masses and the first thing I thought of was safe landing in the event of engine failure or other catastrophic mechanical breakdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to me that it would be possible using modern composites to create some type of aircraft whose default flying configuration is a safe, slow descent. NOT including parachute equipped such as cirrus, has any such craft been designed/flown?&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="2176" LastEditDate="2015-06-12T17:33:14.910" LastActivityDate="2020-03-27T15:35:31.887" Title="Has any aircraft ever been designed such that it could descend safely with no control input?" Tags="&lt;flight-controls&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8818" PostTypeId="2" ParentId="8817" CreationDate="2014-09-29T21:45:51.963" Score="27" Body="&lt;p&gt;Broadly speaking most (if not all) light GA aircraft can &quot;glide safely with no control input&quot; - aircraft are generally designed to have &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_dynamic_modes&quot;&gt;positive dynamic stability&lt;/a&gt;, such that they will return to a stable equilibrium condition (e.g. &quot;level cruise flight&quot;) in the face of most modest upsets. Once configured for cruise flight they can maintain it with little input from the pilot (and if equipped with even a basic autopilot &quot;little input&quot; can often be reduced to &quot;no input&quot; for extended periods of time).&lt;br&gt;&#xA;Whether or not the engine is producing power is largely irrelevant here, save for the fact that if the engine isn't producing power you &lt;em&gt;will&lt;/em&gt; eventually be descending.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Positive stability alone will not make aviation &quot;accessible to the masses&quot; however, nor will autopilots: As with driving a car or riding a motorcycle there are certain &quot;aeronautical decision-making&quot; skills which a pilot &lt;em&gt;must&lt;/em&gt; possess in order to safely fly (and land) an aircraft when everything goes right. If you introduce problems (like engine or instrument failures) the need for a real live pilot becomes even more critical: technology can not yet replace the critical decision making capabilities of a trained human mind.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Particularly in regard to your question about a default flight mode of a controlled descent, even a simple autopilot can already do what you describe: Planes will continue to fly the last autopilot-commanded heading or route until they run out of fuel, at which point they'll start descending (while still attempting to fly the programmed profile).&lt;br&gt;&#xA;What they cannot do is select a suitable landing site, update their flight profile, and fly themselves to a safe landing. For that to happen without human intervention requires a huge amount of luck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a particularly famous example of this kind of luck &lt;a href=&quot;http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001208X09271&amp;amp;ntsbno=CHI98LA055&amp;amp;akey=1&quot;&gt;a Piper Comanche &quot;landed&quot; itself in a field after running out of fuel&lt;/a&gt;, the pilot being unconscious at the time due to carbon monoxide poisoning. The pilot survived and in fact literally walked away from the accident scene, and the aircraft in question is, &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N8452P&quot;&gt;as best I can determine&lt;/a&gt;, still flying.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-09-29T21:45:51.963" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8819" PostTypeId="1" AcceptedAnswerId="8822" CreationDate="2014-09-29T22:47:41.567" Score="27" ViewCount="13459" Body="&lt;p&gt;I am designing a remote controlled airship. I will tune it so that the lift given by Archimedes' Principle will exactly balance the weight of all the structure. It will be propelled by brushless motors with propellers on them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I have understood, for some given velocity $v$ the drag force $D$ will be given by the air pressure, some shape dependent drag coefficient $C_D$, the surface $S$ that the airship offers to the wind, and finally the squared velocity $v^2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to keep some speed, obviously the thrust $T$ must equal the drag $D$. Now, I need to get to some equation for the power that I need to offer such thrust at such speed, given that I am using non-ideal engines, with non-ideal propellers etc. From a barely theoretical point of view, I know that if I want to apply some force to an object that moves at some speed, I will be using some power $P \sim Fv$. Now, since the thrust is generated in some way that actually looks &lt;em&gt;very&lt;/em&gt; dispersive, I would like to know if there exists some relationship between the power $P$, the velocity $v$ and the thrust $T$, given some specific motor and some specific propeller. In particular, what are the parameters that one needs to know to get to this relation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On example, I can imagine that some efficiency parameter for the engine, its RPM rate, its voltage, the diameter of the propeller, the pitch of the propeller, these are all going to be relevant to the equation I am looking for, but I wouldn't know how to explicitly figure out that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It such a relation doesn't exist in an obvious or general way, could you just give me an idea of the efficiency of the propulsion? I mean, I know that $P \geq Tv$, but how much bigger is it in general? Do these quantities share the same order of magnitude, or the dispersion is very big compared to the actual propulsion?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can understand, I am not an expert at all on the subject, so I would appreciate anything that could get me started.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you again!&lt;/p&gt;&#xA;" OwnerUserId="3692" LastActivityDate="2020-10-14T19:47:38.940" Title="Is there any equation to bind velocity, thrust and power?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;airspeed&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8822" PostTypeId="2" ParentId="8819" CreationDate="2014-09-30T06:37:34.700" Score="35" Body="&lt;p&gt;A propeller accelerates the air of density &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; which is flowing through the propeller disc of diameter &lt;span class=&quot;math-container&quot;&gt;$d_P$&lt;/span&gt;. This can be idealized as a stream tube going through the propeller disc:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sfxUA.png&quot; alt=&quot;Section of airstream through propeller&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The air speed ahead is &lt;span class=&quot;math-container&quot;&gt;$v_0 = v_{\infty}$&lt;/span&gt; and the air speed aft of the propeller is &lt;span class=&quot;math-container&quot;&gt;$v_1 = v_0 + \Delta v$&lt;/span&gt;. The propeller effects a pressure change which sucks in the air ahead of it and pushes it out. Since the mass flow must be equal ahead and behind the propeller, the stream tube diameter is bigger ahead of the propeller and smaller downstream. In reality, there is no neat boundary between the air flowing through the propeller and that surrounding it, but for computing thrust this simplification works well if the airspeed is identical across the cross section of the propeller disc.&lt;/p&gt;&#xA;&lt;p&gt;The mass flow (mass &lt;span class=&quot;math-container&quot;&gt;$m$&lt;/span&gt; per unit of time &lt;span class=&quot;math-container&quot;&gt;$t$&lt;/span&gt;, written as a derivation) is: &lt;span class=&quot;math-container&quot;&gt;$$\frac{dm}{dt} = \pi \cdot\frac{d_P^2}{4}\cdot \rho \cdot \left( v_{\infty} + \frac{\Delta v}{2} \right)$$&lt;/span&gt;&#xA;The mass flow is written as the volume of air with density &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; per time, moving through the propeller disk with the diameter &lt;span class=&quot;math-container&quot;&gt;$d_P$&lt;/span&gt; at a speed that is the median between entry and exit speed. The thrust is mass flow times speed change: &lt;span class=&quot;math-container&quot;&gt;$$T = \pi \cdot\frac{d_P^2}{4}\cdot \rho \cdot \left( v_{\infty} + \frac{\Delta v}{2} \right) \cdot \Delta v$$&lt;/span&gt;&#xA;If the engine has the power P, the thrust is net power divided by airspeed in the propeller disk. To arrive at the net power, you multiply the rated engine power by the propeller efficiency &lt;span class=&quot;math-container&quot;&gt;$\eta_{Prop}$&lt;/span&gt; and the electric efficiency &lt;span class=&quot;math-container&quot;&gt;$\eta_{el}$&lt;/span&gt;: &lt;span class=&quot;math-container&quot;&gt;$$T = \frac{P\cdot\eta_{Prop}\cdot\eta_{el}}{\left( v_{\infty} + \frac{\Delta v}{2} \right)}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;A good engine will have an electric efficiency above 90%, and a good propeller will give you an efficiency between 80% and 85%. Efficiency goes up with lower &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt;, so a big, slowly spinning prop is better than a small, fast one.&lt;/p&gt;&#xA;&lt;p&gt;An airship will not move fast, so the &lt;span class=&quot;math-container&quot;&gt;$v_{\infty}$&lt;/span&gt; is low. In the static thrust case it is zero, and the thrust equation can be simplified:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$T_0 = \frac{P\cdot\eta_{Prop}\cdot\eta_{el}}{\sqrt{\frac{2\cdot T_0}{\pi\cdot d_P^2\cdot\rho}}} = \sqrt[\LARGE{3\:}]{P^2\cdot\eta_{Prop}^2\cdot\eta_{el}^2\cdot\pi\cdot \frac{d_P^2}{2}\cdot\rho}$$&lt;/span&gt;&#xA;To actually know your &lt;span class=&quot;math-container&quot;&gt;$v_{\infty}$&lt;/span&gt;, you need to know the drag &lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt; of your airship. The general equation is &lt;span class=&quot;math-container&quot;&gt;$$D = A\cdot c_D\cdot\frac{\rho}{2}\cdot v^2$$&lt;/span&gt; with &lt;span class=&quot;math-container&quot;&gt;$A$&lt;/span&gt; the frontal area of the ship and &lt;span class=&quot;math-container&quot;&gt;$c_D$&lt;/span&gt; its drag coefficient. &lt;a href=&quot;http://dl.kashti.ir/ENBOOKS/NEW/FDD.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;S. Hörner&lt;/a&gt; (page 14-1) gives the drag coefficient of LZ126 (later Los Angeles) as &lt;span class=&quot;math-container&quot;&gt;$c_D = 0.023$&lt;/span&gt; for the hull alone and &lt;span class=&quot;math-container&quot;&gt;$c_D = 0.071$&lt;/span&gt; for the complete ship, including nacelles, fins and all.&#xA;A similar result is given in &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1932/naca-report-394.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA Report 394&lt;/a&gt; which documents the tests done on models of Goodyear Zeppelins in the NACA variable density wind tunnel in 1932. There is another source, NACA Report 117 by Max Munk, written in 1921 and supposedly collecting the results of German measurements on Zeppelins &lt;a href=&quot;https://strives-uploads-prod.s3.us-gov-west-1.amazonaws.com/19930091181/19930091181.pdf?AWSAccessKeyId=AKIASEVSKC45ZTTM42XZ&amp;amp;Expires=1602704781&amp;amp;Signature=X61KzAKkwoXjHLjhLJ5DiprlRGc%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;which can be found here&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Your model will not achieve such low values, however, because it will fly at a lower Reynolds number, which means that friction will be higher in relation to other forces. Depending on the size and speed of your model, pick a value between 0.15 and 0.3 for first calculations.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-10-14T19:47:38.940" LastActivityDate="2020-10-14T19:47:38.940" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="8823" PostTypeId="2" ParentId="8809" CreationDate="2014-09-30T07:59:29.370" Score="56" Body="&lt;p&gt;My experience, speaking as a pilot who had to retire in 1999 from a small 747 carrier when the US age 60 rule was in effect, was that NONE of us close to retirement wanted to retire. More often than not, the attitude was, &quot;It's hard to believe they actually pay us for this.&quot; We didn't want to quit; we were at the top of our game; the world was our playground. The money was also very good!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insofar as worries of a &quot;steep decline in capabilities of older pilots,&quot; there is no statistical evidence that I am aware of to support this, although whether there is at least some decline has been a matter of controversy. You can Google &quot;age 60 rule&quot; and find reams (screen loads?) of info on this. A particularly good link IMO is &lt;a href=&quot;http://www.avweb.com/news/aeromed/181875-1.html&quot;&gt;http://www.avweb.com/news/aeromed/181875-1.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes a good air carrier captain is not so much being a good stick or quick reactions, but being situationally aware, learning what to avoid, being able to read the politics of a situation (especially in third world countries), and other things that come to one primarily through experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, when I hired on to my second 747 carrier as an f.o., I was paired with a relatively young, fresh captain. I was older, had been a 747 captain at a previous carrier, and had more hours in the airplane. We landed in Harare, Zimbabwe to pick up a charter. Our APU was inop, so as per standard procedure, we left #4 engine running to supply the pneumatic air we would need to start the other engines. However, when the ground handlers told us there would be a delay of a couple of hours, the captain ordered the engines shut down, saying that we would use a huffer to start. Both the f.e. and I simultaneously objected, both saying in so many words that we couldn't depend on there being a usable huffer in Harare. The captain ignored us and shut down the engines, believing that the capital of a country would surely have such. The fun started when he asked for a huffer to be hooked up for our start. Long story short, what would have been but a two hour delay turned into something like a 10 hour delay. It included hooking up 4 different beat up old huffers to the airplane, but even using the two best at once (the 747 can accommodate 2 hookups) failed. Finally, a mechanic worked on those two best units and managed to get enough pressure to start us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain was a good stick; he just hadn't had enough experience.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-09-30T07:59:29.370" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8824" PostTypeId="2" ParentId="8598" CreationDate="2014-09-30T08:33:13.123" Score="12" Body="&lt;p&gt;Valse Des Ailerons (&lt;em&gt;Waltz of Ailerons&lt;/em&gt;) or VDA is a nickname for the Load Alleviation Function (LAF) which is part of the flight control system. LAF uses all ailerons and spoiler 6 to 8 to alleviate the fatigue and static loads on the wings by reducing the wing bending moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It consist of various sub functions dealing with passive load alleviation (based on commanded load factor from normal law) and active load control based on measured accelerations in pylons under the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this it already follows that passive load alleviation requires normal law for load factor inputs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a document circulating on the internet which seems to be an official Airbus Pilot Briefing for A380 pilots called &quot;Flight Deck and Systems Briefing for pilots, issue 2&quot;. In the section about the Flight Control Systems under auxiliary system the following is said about the LAF:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Load Alleviation Function (LAF)&lt;p&gt; The objective of the LAF is to reduce structure fatigue and static loads on the wing during maneuvers&#xA;  and turbulence.&lt;br&gt; Spoilers 6 to 8 and all the ailerons are involved&#xA;  in the LAF.&lt;br&gt;&#xA;  &lt;strong&gt;&lt;em&gt;The LAF is available in normal law only&lt;/em&gt;&lt;/strong&gt;.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis added by me)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So your feeling that Valse des Ailerons is only active in Normal Law is correct.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Update: Based on the A380 flight crew manual, it depends—&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SLxjk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SLxjk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w8Kr4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w8Kr4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-07-30T17:53:30.693" LastActivityDate="2017-07-30T17:53:30.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8825" PostTypeId="1" AcceptedAnswerId="8905" CreationDate="2014-09-30T09:45:39.593" Score="15" ViewCount="4884" Body="&lt;p&gt;On several B77 photos, I notice that flaps just behind the engines are not always coordinated with the others flaps. On this &lt;a href=&quot;http://www.airliners.net/photo/Air-Canada/Boeing-777-333-ER/2484248&quot; rel=&quot;noreferrer&quot;&gt;photo&lt;/a&gt; flaps are extended but not behind the engine whereas on this &lt;a href=&quot;http://www.airliners.net/photo/United-Airlines/Boeing-777-222-ER/0622410/&quot; rel=&quot;noreferrer&quot;&gt;photo&lt;/a&gt; all flaps are extended. Given the position of this particular flap, I suppose there is something to do with the interaction between flaps and engine. Given the difference between the two photos, it may also have something to do with spoiler extension. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: OK the two photos are not the same plane, but I find a &lt;a href=&quot;http://www.youtube.com/watch?v=WIcFCoIQcSw&amp;amp;t=140&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt; where it is obvious this piece of flap is not always coordinated with the rest of the flaps. When looking at the video I first thought it was a flaperon, but after the flaps are extended, it deflects upward several times without making the plane banking.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2014-10-03T15:35:24.107" LastActivityDate="2020-02-12T14:11:35.263" Title="How does the particular piece of flap behind an engine on a B777 work?" Tags="&lt;flaps&gt;&lt;boeing-777&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8826" PostTypeId="2" ParentId="8817" CreationDate="2014-09-30T13:47:45.667" Score="13" Body="&lt;p&gt;Not really a plane, but Autogyro are really safe even when motor shutdowns.&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Autogyro&quot;&gt;http://en.wikipedia.org/wiki/Autogyro&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For having tried one, when motor stops, it just descends slowly (maybe 1m/s max), and you just have to make little corrections before landing, to convert vertical speed to horizontal speed. It's really like an &quot;air bike&quot;&lt;/p&gt;&#xA;" OwnerUserId="3698" LastActivityDate="2014-09-30T13:47:45.667" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8827" PostTypeId="1" CreationDate="2014-09-30T14:11:12.237" Score="4" ViewCount="2135" Body="&lt;p&gt;I'm curious about commercial airplane efficiency vs private jet efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was trying to compare something like a modern 737 flying a full commercial flight from NYC to LA vs an Embraer Phenom 300 at full capacity (8 people) flying the same route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are many variations of the 737, so can we just use the most common commercially flown 737? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If fuel costs were the same (I understand that big airlines get discounts) is there a simple way to compare the flights simply in terms of cost of the flight, or how much fuel each plane would need for the flight? I didn't want to get into profit, crew, etc. Simply the cost of flying both planes from NYC to LA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for any help.&lt;/p&gt;&#xA;" OwnerUserId="3694" LastEditorUserId="572" LastEditDate="2015-02-24T11:03:20.917" LastActivityDate="2015-02-24T11:03:20.917" Title="How do you compare private jet and commercial jet efficiency?" Tags="&lt;commercial-aviation&gt;&lt;cost&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8828" PostTypeId="2" ParentId="8827" CreationDate="2014-09-30T14:37:30.273" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Simply the cost of flying both planes from NYC to LA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The 737 will cost a lot more than the 8-seat bizjet. This kind of comparison is just about useless - direct cost per seat-kilometer is as basic as you can get, and even that one is very rough. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crew and maintenance are inescapable costs so excluding them makes the calculations even more skewed. Landing fees are based on gross weight class divided into the number of passengers, facility fees are actual number of passengers on board, parking is by size, navigation is based on ability-to-pay (the 737 pays, because it's a commercial flight. A privately owned Cessna gets ATC for free). The bizjet can use smaller airfields that can be hours closer to the group's destination so once you factor in ground transportation (and lower airport fees) and employee time the bizjet can actually work out cheaper per seat than Delta. But you do have to consider everything.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-09-30T14:37:30.273" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8829" PostTypeId="2" ParentId="8827" CreationDate="2014-09-30T15:52:25.020" Score="7" Body="&lt;p&gt;This has nothing to do with private vs. commercial. The size difference is what matters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you compare the absolute cost of moving the aircraft from NYC to LA, the 737 will be way more expensive, regardless of version. Since you asked only which one is more expensive, I don't see a need for detailed reasoning. Just use the data provided in &lt;a href=&quot;https://aviation.stackexchange.com/questions/8652/fuel-efficiency-of-airbus-320-200-at-various-loads/8654#8654&quot;&gt;this answer&lt;/a&gt; and it becomes obvious that fuel consumption will scale with the mass of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all passengers have to share the cost, the cost per passenger will be much higher in case of the Phenom 300. Or almost any other Bizjet. The Phenom will even need to land somewhere enroute to refuel. The &lt;a href=&quot;http://www.distancefromto.net/distance-from/New+York/to/Los+Angeles&quot; rel=&quot;nofollow noreferrer&quot;&gt;distance from NYC to LA&lt;/a&gt; is bigger than the &lt;a href=&quot;http://www.embraerexecutivejets.com/en-US/jets/phenom-300/Pages/overview.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;maximum range with full payload&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that kind of comparison does not make sense - both airplanes have been designed for different purposes, so their strengths are in their unique field of use. They do not transfer well to that of different aircraft types.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-10-01T06:25:29.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8830" PostTypeId="2" ParentId="8827" CreationDate="2014-09-30T16:38:49.350" Score="6" Body="&lt;p&gt;Hourly fuel costs for a private jet can run from 800-2000/hr USD.  So the 5 hours from NY-LA range from 4,000 to 10,000.  But fuel is only part of the equation.  On also has to figure in cost of ownership issues such as parking/hangar, insurance, engine reserves, avionics reserves, annual inspection reserve, etc.  Also there are additional direct operating costs such as pilot salaries, crew salaries, tied down/gate fees.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some fractional ownership programs where all of this is loaded it is not uncommon to end up with a 4,000-8,000/hr figure.  This assumes you have already made a fractional payment of around 200,000-500,000 depending upon type of plane and percentage of ownership share (1/6, 1/12, ...).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also other programs where you rent the jet, crew, etc, but I have not looked at those figures.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-09-30T16:38:49.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8831" PostTypeId="2" ParentId="8825" CreationDate="2014-09-30T17:22:35.300" Score="6" Body="&lt;p&gt;To expand slightly on ratchet freak's comment, they're different models of plane, with different engines.  The first photo is a 777-300ER with General Electric engines (the only kind fitted on -300ERs); the second is a 777-200ER with Pratt and Whitney engines (one of three engine options). Looking at other photos, it appears that the flaps directly behind the engines of -300ERs don't extend nearly as far as those on the rest of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And note that there are significant differences between the -200ER and -300ER. For example,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the fuselage of the -300ER is 10m longer and the wingspan is 4m longer;&lt;/li&gt;&#xA;&lt;li&gt;the -300ER seats 70+ more people;&lt;/li&gt;&#xA;&lt;li&gt;the maximum take-off weight of the -300ER is about 40 tonnes higher.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2014-09-30T22:34:28.807" LastActivityDate="2014-09-30T22:34:28.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8833" PostTypeId="2" ParentId="8827" CreationDate="2014-09-30T20:02:40.273" Score="1" Body="&lt;p&gt;I just found this list of various plane models and information about them such as average fuel burn and total variable cost/hour. If anyone is interested: &lt;a href=&quot;http://www.duncanaviation.aero/files/aircraft_sales/Business-Jet-Model-Market-Summary.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.duncanaviation.aero/files/aircraft_sales/Business-Jet-Model-Market-Summary.pdf&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3694" LastActivityDate="2014-09-30T20:02:40.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8834" PostTypeId="1" AcceptedAnswerId="8837" CreationDate="2014-09-30T21:18:10.663" Score="24" ViewCount="4421" Body="&lt;p&gt;I don't understand why sometimes the fuel used for a flight is discussed in terms of fuel used per time.&lt;br&gt;&#xA;I think I have seen it a couple of times here - not sure whether it was in some common context.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think that it's much more relevant how much fuel is used per distance in almost every respect, except designing engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, this &lt;a href=&quot;https://aviation.stackexchange.com/a/8830/1875&quot;&gt;answer&lt;/a&gt; to the recent question &lt;a href=&quot;https://aviation.stackexchange.com/questions/8827/commercial-vs-private-efficiency&quot;&gt;How do you compare private jet and commercial jet efficiency?&lt;/a&gt; uses &quot;x/hr USD&quot; as in &quot;Hourly fuel costs for a private jet can run from 800-2000/hr USD.&quot; I'm sure I noticed similar cases a couple of times.&lt;br&gt;&#xA;It's fuel cost per time, instead of fuel weight or volume, but that does not make a difference in regards to the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe there is a reason based on some &quot;tradition&quot;?&lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2017-05-15T15:41:42.173" Title="Why is fuel usage discussed per time, not per distance?" Tags="&lt;fuel&gt;" AnswerCount="5" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8835" PostTypeId="2" ParentId="8834" CreationDate="2014-09-30T21:30:39.833" Score="2" Body="&lt;p&gt;Technically, the best metric would be fuel flow, per weight. For a simple answer, you burn far more fuel when you're heavier, than when you're lighter.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-09-30T21:30:39.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8836" PostTypeId="2" ParentId="8834" CreationDate="2014-09-30T22:28:54.283" Score="11" Body="&lt;p&gt;It’s an interesting question. Most calculations that pilots do are based on fuel flow per hour. Several regulations include these types of calculations as well: you must have a fuel reserve for (say) 30 or 60 minutes beyond your final destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some questions, eg comparing a small plane to a car in fuel economy, fuel per distance is interesting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, some other reasons why fuel per distance may not be as useful as fuel per hour:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind. A tailwind versus a headwind can dramatically change the fuel per mile, but doesn’t change the fuel per hour (if your airspeed is the same)&lt;/li&gt;&#xA;&lt;li&gt;Comparison to other planes. If everyone compares figures per hour, then you have a solid basis for comparison. Of course, comparing a jet’s fuel per hour compared to a prop plane’s fuel per hour would be silly, but planes in the same class may have somewhat comparable cruising speeds&lt;/li&gt;&#xA;&lt;li&gt;Taxi, climb and descent. The cruising speed of a plane might not be that relevant for short flights, when most of the time is not spent cruising&lt;/li&gt;&#xA;&lt;li&gt;Pilot Operating Handbooks (POH)s tell you many figures in gallons per hour, including fuel usage while climbing, at different speeds, different atmosphere conditions etc&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are just a few. I guess neither fuel per hour nor fuel per distance is useful by itself—it depends entirely on what you want to compare.&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2014-09-30T22:28:54.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8837" PostTypeId="2" ParentId="8834" CreationDate="2014-09-30T22:42:10.947" Score="44" Body="&lt;p&gt;Unlike with driving, in aviation the major variable when planning fuel consumption isn't how far you're traveling but how &lt;em&gt;long&lt;/em&gt; you're traveling: Distance traveled in aircraft is a &lt;em&gt;derived&lt;/em&gt; value (calculated from groundspeed and time - groundspeed also being a derived value affected by many factors including wind).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot may not readily know their groundspeed (it can be quite different from airspeed), but at a given power setting they know an engine will burn a specific quantity of fuel per unit time, therefore fuel consumption is generally expressed that way (in gallons per hour or pounds per hour), and if they know how long they've been flying they can reliably estimate how much fuel they've burned, how much is left in the tanks, and how much longer they can keep flying before running out of fuel.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To illustrate why this is superior for flight planning consider the following (extremely simplified) flights fitting the following profile:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iBlz4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iBlz4m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A 200 nautical mile trip&lt;/li&gt;&#xA;&lt;li&gt;An airspeed of 100 knots&lt;/li&gt;&#xA;&lt;li&gt;A fuel burn of 10 gallons per hour&lt;/li&gt;&#xA;&lt;li&gt;A 25-gallon fuel tank.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Scenario 1: No Wind&lt;/strong&gt;&lt;br&gt;&#xA;With no wind the flight will take two hours to complete.&#xA;The groundspeed is 100 knots.&lt;br&gt;&#xA;The aircraft will burn 20 gallons of fuel.&lt;br&gt;&#xA;The fuel efficiency is 10 miles per gallon.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this scenario we land with 5 gallons of fuel left in the tank - that corresponds to 30 minutes, which is the minimum legal reserve for day VFR flight per FAA regulations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Scenario 2: 25 Knot Headwind&lt;/strong&gt;&lt;br&gt;&#xA;With a 25 knot headwind the flight will take about 2:40 minutes to complete.&lt;br&gt;&#xA;The groundspeed is 75 knots.&lt;br&gt;&#xA;The aircraft will burn 27 gallons of fuel.&lt;br&gt;&#xA;The fuel efficiency is 7.5 miles per gallon.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this scenario we run out of fuel 2:30 into the flight. Running out of fuel is generally considered to be a Bad Thing: The passengers complain, and the FAA asks a lot of uncomfortable questions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Scenario 3: 25 Knot Tailwind&lt;/strong&gt;&lt;br&gt;&#xA;With a 25 knot tailwind the flight will take about 1:40 minutes to complete.&lt;br&gt;&#xA;The groundspeed is 125 knots.&lt;br&gt;&#xA;The aircraft will burn 16 gallons of fuel.&lt;br&gt;&#xA;The fuel efficiency is 12.5 miles per gallon.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this scenario we land with almost an hour of fuel still in the tank - a very comfortable reserve. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On longer flights, and in slower aircraft, the effects of wind can be extremely pronounced, and a 5 or 10 knot difference from the forecast winds can mean the difference between arriving at your destination or having to add a fuel stop.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2014-10-01T13:17:13.093" LastActivityDate="2014-10-01T13:17:13.093" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8838" PostTypeId="2" ParentId="8834" CreationDate="2014-10-01T01:07:18.453" Score="5" Body="&lt;p&gt;For a given amount of fuel, the engines will only run for a certain amount of time. Distance is irrelevant. If you circle going nowhere for one hour, you've still consumed one hour's worth of fuel. If your airspeed is 100 knots and flying into a 100 knot headwind, you're still consuming fuel even though the distance traveled is 0.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastEditorUserId="62" LastEditDate="2017-05-15T15:41:42.173" LastActivityDate="2017-05-15T15:41:42.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8840" PostTypeId="1" AcceptedAnswerId="8844" CreationDate="2014-10-01T08:49:20.017" Score="34" ViewCount="8878" Body="&lt;p&gt;I recently flew on an Airbus A319. When boarding the aircraft from the front entrance we passed in front of the left engine. The fan blades were spinning and there was a rattling noise (like when a chain is being rolled up) coming from the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this normal? What causes this sound? Is it the fan blades that are somehow loose?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="65" LastEditDate="2015-03-12T14:46:13.667" LastActivityDate="2019-08-21T19:00:08.133" Title="Why was there a rattling noise coming from the left engine of A319?" Tags="&lt;jet-engine&gt;&lt;noise&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8841" PostTypeId="1" AcceptedAnswerId="8842" CreationDate="2014-10-01T08:57:55.257" Score="15" ViewCount="24558" Body="&lt;p&gt;How do the big planes (e.g. A380 or 737) flying on high altitudes manage to get fresh air for passengers and crew during the flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the inner space of the plane used for passengers and crew is sealed and the pressure is maintained within some range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in standard flight altitude of about 10-14 km there is not enough oxygen to breathe.  I am not sure whether the standard oxygen ratio is still about 21% and you only have less air (lower pressure).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We talked two possible solutions and maybe I am still wrong:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;using some pumps and small pressure tanks to suck in air from outside till we get higher pressure and then use some valves to &quot;replace&quot; the breathed up air with the fresh one&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;use some pressure tanks loaded with oxygen + some cleaning devices to clean the air and add oxygen to keep the same oxygen level - but this would need to get the oxygen before take-off and such tanks would be really dangerous&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So how is it in reality?&lt;/p&gt;&#xA;" OwnerUserId="3704" LastEditorUserId="65" LastEditDate="2014-10-01T13:34:16.487" LastActivityDate="2020-04-16T21:36:21.560" Title="How do big planes like 737 manage fresh air for passengers during flight?" Tags="&lt;airliner&gt;&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8842" PostTypeId="2" ParentId="8841" CreationDate="2014-10-01T09:09:44.260" Score="14" Body="&lt;p&gt;They &lt;a href=&quot;http://en.wikipedia.org/wiki/Bleed_air&quot; rel=&quot;nofollow noreferrer&quot;&gt;bleed&lt;/a&gt; hot compressed air from inside the jet engines, cool it down and pass it into the cabin. There are outlet valves in the fuselage that allow stale air out and which control cabin pressure and air-refresh rates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few aircraft types, such as the 787, now use a compressor to take in air from under the aircraft. They do this because it can be more fuel-efficient (not for any other reason). It is arguable whether it creates an additional fire hazard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/8535/1289&quot;&gt;Why is the compressed air (from Engine Compressors) taken from High Pressure (HP) stage instead of Low Pressure (LP) stage&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/8502/1289&quot;&gt;Can an aircraft re-pressurize at high altitude?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/948/1289&quot;&gt;Is constant air pressure maintained inside the fuselage?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-10-01T09:16:47.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8843" PostTypeId="2" ParentId="8841" CreationDate="2014-10-01T09:25:36.413" Score="1" Body="&lt;p&gt;Bleed air from the engine is used to power a &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_cycle_machine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pneumatic Air Cycle Kit (PACK)&lt;/a&gt; which takes in outside air heats it and compresses it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanism is entirely mechanical using turbines and heat exchangers and engine bleed air is isolated from the air destined to the cabin to avoid oils and fumes entering the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to &lt;a href=&quot;https://aviation.stackexchange.com/a/5033/609&quot;&gt;How hot would pressurized air get if the air conditioning failed?&lt;/a&gt; ex^plained in detail how a PACK works.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-10-01T09:58:26.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8844" PostTypeId="2" ParentId="8840" CreationDate="2014-10-01T09:34:23.290" Score="33" Body="&lt;p&gt;Yes indeed, the fan blades are loose and rattle in their sockets when the fan is freewheeling in the wind. Once the engine is running, centrifugal forces will make sure they do not rattle any longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The base of the fan blades have a shape like a fir tree, and they slide into sockets on the fan disk with a loose fit. When the fan is spinning slowly, they will sit on one side of the socket on the way up, and gravity will pull them into the opposite side on the way down. The rattling is caused by one blade after another falling into that opposite position once they rotate over the top.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qpKPS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for the bad picture (&lt;a href=&quot;http://www.thaitechnics.com/engine/tg7/turbine_blade.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) - I could not find a better one right now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are concepts to move to bladed disks (&quot;blisks&quot;), but while they are lighter and don't rattle, they are a headache once a single blade is damaged and needs to be replaced. Therefore, the single, easily removable fan blades are the solution of choice in all gas turbines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-08-21T19:00:08.133" LastActivityDate="2019-08-21T19:00:08.133" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="8845" PostTypeId="2" ParentId="8834" CreationDate="2014-10-01T09:37:15.187" Score="7" Body="&lt;p&gt;As explained in other answers, fuel/time is better for planning, but now let's move to the cockpit!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel/time is easily and accurately measured by the vehicle instrumentation and, as a plane throttle is mostly kept fixed, the value won't change much allowing you to use it to do estimations. A very convenient one is the residual flight-time: this tells you how much you can wait for landing and how much this wait will cost. From the fuel/time is not hard to get the range of autonomy once you know the ground speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel/distance, instead, will make your life much harder if you need to know how much you can wait above an airport!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary, driving a car you want to know how far you can get to reach a gas station, not for how long you can drive around it, that's why fuel/distance is much better in this case.&lt;/p&gt;&#xA;" OwnerUserId="2345" LastEditorUserId="2345" LastEditDate="2014-10-01T09:59:56.360" LastActivityDate="2014-10-01T09:59:56.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8846" PostTypeId="1" AcceptedAnswerId="8848" CreationDate="2014-10-01T12:10:53.393" Score="11" ViewCount="54478" Body="&lt;p&gt;What happens when an aircraft breaks the sound barrier? Why can't it break the sound barrier near the ground?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="7532" LastEditDate="2016-02-26T20:02:04.613" LastActivityDate="2020-07-11T20:35:08.707" Title="What happens when an aircraft breaks the sound barrier?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8847" PostTypeId="2" ParentId="8846" CreationDate="2014-10-01T12:42:15.333" Score="11" Body="&lt;p&gt;This is a rather broad question, so I'll try to keep it brief.  &lt;a href=&quot;http://www.scientificamerican.com/article/what-happens-when-an-airc/&quot; rel=&quot;noreferrer&quot;&gt;It just so happens that Scientific American covered your question in detail in an article on March 11, 2002&lt;/a&gt;.  Although I think the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sound_barrier&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia Page&lt;/a&gt; does a better job of describing it than the SciAm article, but is more a history.  &lt;a href=&quot;http://www.uu.edu/dept/physics/scienceguys/2001apr.cfm&quot; rel=&quot;noreferrer&quot;&gt;Union University gets to the meat of it though&lt;/a&gt;.  Some of the key things that happen are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A plane produces sound that radiates out from the plane in all directions. The waves propagating in front of the plane get crowded together by the motion of the plane. As the plane approaches the speed of sound, the sound pressure &quot;waves&quot; pile up on each other compressing the air. The air in front of the plane exerts a force on the plane impeding its motion. As the plane approaches the speed of sound, it approaches this invisible pressure barrier set up by the sound waves just ahead of the plane. The compressed air in front of the plane exerts a much larger than usual force on the plane. There is a noticeable increase in the aerodynamic drag on the plane at this point, hence the notion of breaking through the &quot;sound barrier.&quot; When a plane exceeds the speed of sound it is said to be supersonic.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Anything exceeding the speed of sound creates a &quot;sonic boom&quot;, not just airplanes. An airplane, a bullet, or the tip of a bullwhip can create this effect; they all produce a crack. This pressure change created by the sonic boom can be quite damaging. In the case of airplanes, shock waves have been known to break windows in buildings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The most apparent thing that happens is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sonic_boom&quot; rel=&quot;noreferrer&quot;&gt;sonic boom&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of the images you see on the internet of aircraft breaking the sound barrier are really just shockwaves (condensation) that happen before reaching the speed of sound.  Shockwave propagation starts happening before actually going supersonic because of boundary layers and the air having to move out of the way of the aircraft (as I understand it).  But the pictures look really, really cool!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XwEIQ.jpg&quot; alt=&quot;FA-18 with condensation shockwaves&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice physics book type of discussion on shockwaves: &lt;a href=&quot;http://physics.info/shock/&quot; rel=&quot;noreferrer&quot;&gt;http://physics.info/shock/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And actually, aircraft are perfectly capable of breaking the sound barrier near the ground.  It's just harder as ratchet freak states in his comment, and also there are a lot of rules against it.  &lt;/p&gt;&#xA;" OwnerUserId="3268" LastEditorUserId="3268" LastEditDate="2014-10-01T13:30:20.260" LastActivityDate="2014-10-01T13:30:20.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8848" PostTypeId="2" ParentId="8846" CreationDate="2014-10-01T12:45:14.773" Score="30" Body="&lt;p&gt;The expression &amp;quot;sound barrier&amp;quot; was created maybe 70 years ago when approaching the speed of sound made aircraft react in unanticipated ways. Actually, there is no fixed barrier, and in reality the transition can be rather smooth, provided the aircraft and its pilot &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430?r=SearchResults&amp;amp;s=2%7C13.9767#57430&quot;&gt;are prepared for it&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The speed of sound is the maximum speed with which small pressure changes will propagate through a medium, so at subsonic speed the air ahead of the aircraft can react to the approaching aircraft. Also, while local air density changes only little at subsonic speed, air density changes become dominant at supersonic speed. To make way for an approaching aircraft, subsonic air will speed up &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430#57430&quot;&gt;while supersonic air will slow down&lt;/a&gt; so that density increases to make way for the supersonic aircraft.&lt;/p&gt;&#xA;&lt;p&gt;At subsonic speed, pressure and speed will change smoothly while air flows around the aircraft. As a consequence, the center of local pressure changes (its lift force) acts at around one quarter of chord, such that the aircraft is balanced when its center of gravity is at the same location.&lt;/p&gt;&#xA;&lt;p&gt;At supersonic speeds, the air will be taken by surprise - at one moment all was calm and quiet, and suddenly the air molecules get kicked around by an unknown intruder. Pressure changes suddenly, through a shock, so instead of a smooth transition, at supersonic speed there are regions of similar pressure, separated by sudden drops or jumps. As a consequence, the center of pressure changes shifts backwards to 50% of chord. If the center of gravity remains at a quarter chord, the consequence is a strong pitch-down moment: The aircraft will nosedive.&lt;/p&gt;&#xA;&lt;p&gt;To make matters worse, a control surface deflection, which could redistribute the lift between wing and tail surface, will not necessarily work in the same way as it would at subsonic speed: the aircraft might become uncontrollable. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;this answer&lt;/a&gt; for a mode detailed explanation.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X2dlm.jpg&quot; alt=&quot;sound propagation&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The cone you see in the right picture is a Mach cone, which would be caused by a supersonic aircraft. The picture was shamelessly copied from &lt;a href=&quot;http://hronrad.wordpress.com/2012/04/25/two-wings-is-megl-che-one-1-some-notes-about-sound/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this blog&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The trick is now to give the air some advance warning where it counts, even when the aircraft travels at supersonic speed. This can be achieved with wing sweep, because if the sweep angle is larger than the cone angle in which pressure changes will propagate at supersonic flight speed, the air flowing over the wing will be forewarned, thus reacting similarly to subsonic flow. To correct for the inevitable shift in the center of pressure, the tail surfaces are bigger and full-flying in supersonic aircraft, so they work in trans- and supersonic flow. Also, by pumping fuel, the center of gravity can be shifted backwards, so less trim change is needed.&lt;/p&gt;&#xA;&lt;p&gt;The sound barrier can be broken at any altitude, if the aircraft has a sufficiently powerful engine and is stiff enough. Normally, to save weight, the designers set a limit for maximum dynamic pressure (= air density times air speed squared, divided by two), so the structural deformation at this maximum dynamic pressure is small enough. Note that the deflection of its ailerons will deform the wing of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter&lt;/a&gt; at maximum dynamic pressure to an extent that three quarters of aileron effectiveness is lost - the ailerons cause a twisting moment which warps the wing such that it works like the wing warping mechanism in the Wright Flyer, only in opposite direction to the aileron input.&lt;/p&gt;&#xA;&lt;p&gt;Since density drops with increasing altitude, the same dynamic pressure is reached at higher speed, allowing aircraft to fly faster the higher they fly. The next limit is given by the local heat near the stagnation line. If air is decelerated, its temperature will &lt;a href=&quot;http://en.wikipedia.org/wiki/Stagnation_temperature&quot; rel=&quot;nofollow noreferrer&quot;&gt;increase with the square of the speed difference&lt;/a&gt;. The maximum continuous speed of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22&lt;/a&gt; was reduced from Mach 1.8 to Mach 1.6 to avoid overheating the sensitive composite wing structure.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-07-10T03:36:01.467" LastActivityDate="2020-07-10T03:36:01.467" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="8850" PostTypeId="1" CreationDate="2014-10-01T13:04:22.203" Score="3" ViewCount="172" Body="&lt;p&gt;Although this question relates directly to the NTSB findings on TWA Flt800, I was always puzzled and dissatisfied with the reason that failure in the instrument wiring harness inside the center wing fuel tank(CWT) caused the unvented fumes(a failure in itself) to explode; given that instrument circuits use microamps at 28vdc, resulting in less than .02Joules at best to transmit signals. A probe heater of course would be different, but that wasn't given as the reason. Are there any other instances where wires 'shorted' in an instrumentation circuit could cause sufficient energy to create a spark?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is not about &quot;what really did happen&quot; to TWA800; this is about whether or not the NTSB(National Transportation Safety Board) made a correct analysis in implicating Instrumentation Wiring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;A joule (J) is a unit of measurement of electrical work or energy; 1 J&#xA;  is the amount of work done by 1 watt of power in 1 second. The power&#xA;  supplied to the FQIS components through the cockpit fuel gauge (0.02&#xA;  mJ) is about 10 percent of the minimum ignition energy (MIE)&#xA;  requirement (0.25 mJ) for hydrocarbon fuels, referenced by the&#xA;  American Petroleum Institute Recommended Practice 2003 (API 2003),&#xA;  Protection Against Ignitions Arising out of Static, Lightning, and&#xA;  Stray Currents, fifth edition, December 1991&lt;/em&gt; Taken from &lt;a href=&quot;http://www.ntsb.gov/doclib/reports/2000/AAR0003.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3671" LastEditorUserId="3671" LastEditDate="2014-10-05T01:28:06.400" LastActivityDate="2014-10-05T01:28:06.400" Title="Can a short in instrumentation wiring create enough 'spark' to ignite unvented fuel fumes?" Tags="&lt;emergency&gt;" AnswerCount="0" CommentCount="16" ClosedDate="2014-10-01T16:29:27.717" ContentLicense="CC BY-SA 3.0" />
  <row Id="8851" PostTypeId="1" AcceptedAnswerId="8858" CreationDate="2014-10-01T14:22:35.243" Score="21" ViewCount="5083" Body="&lt;p&gt;What is the difference of design between a propeller designed to be powered by the wind (i.e. those huge wind power turbine blades) and those designed to be used to propel a plane that are powered by an engine (i.e. a Cessna 172's props)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(To be clear, I'm talking about one that is powered &lt;em&gt;by&lt;/em&gt; the air vs one that powers &lt;em&gt;through&lt;/em&gt; the air.)&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="572" LastEditDate="2015-02-24T11:02:19.480" LastActivityDate="2018-12-08T02:49:33.650" Title="Are there design differences between propellers powered by air (wind-power) and propellers for aviation?" Tags="&lt;propeller&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8852" PostTypeId="1" AcceptedAnswerId="8859" CreationDate="2014-10-01T14:27:58.007" Score="7" ViewCount="2214" Body="&lt;p&gt;During emergencies pilots are authorised to dump fuel, but is there any way or method to recover the fuel that has been jettisoned?&lt;/p&gt;&#xA;" OwnerUserId="3710" LastEditorUserId="97" LastEditDate="2014-10-29T01:09:25.287" LastActivityDate="2019-09-15T14:20:28.387" Title="Is it possible to recover dumped fuel?" Tags="&lt;fuel-dumping&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8853" PostTypeId="2" ParentId="8852" CreationDate="2014-10-01T14:32:12.730" Score="3" Body="&lt;p&gt;The pilot can either keep circling around to burn it off (doesn't conserve it) or just land overweight without jettisoning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Burning it off is not an option if you want to get on the ground &lt;strong&gt;now&lt;/strong&gt; to deal with the emergency. And landing overweight can create a new emergency if the gear collapses/too many tires blow.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-01T14:32:12.730" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8854" PostTypeId="2" ParentId="8841" CreationDate="2014-10-01T14:38:43.797" Score="7" Body="&lt;p&gt;Airplanes basically draw in outside air, compress it, and send it to the cabin. RedGrittyBrick lists some related questions about this process. Most airplanes use bleed air from the engines, using the compressors in the engines to do the compressing. Although in normal operation this will only bring in outside air, engine issues can cause &lt;a href=&quot;http://avherald.com/h?article=46c6beb4&quot;&gt;fumes to enter the cabin&lt;/a&gt;. The 787 uses an electric compressor that draws from separate intakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with breathing at high altitudes is not necessarily the lack of oxygen, but the low pressure. Humans need a certain &lt;a href=&quot;http://www.altitude.org/partial_pressure.php&quot;&gt;partial pressure&lt;/a&gt; of oxygen for the lungs to work properly, and as pressures drop, the oxygen is less effective at getting into the bloodstream, which results in &lt;a href=&quot;http://en.wikipedia.org/wiki/Hypoxia_%28medical%29&quot;&gt;hypoxia&lt;/a&gt;. So keeping the cabin pressurized is what allows the occupants to breathe normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information about the cabin environment, see &lt;a href=&quot;http://www.donaldson.com/en/aircraft/cabinairquality/supportDocs/18%20Issues%20Pertaining%20to%20Flight%20Attendant%20Comfort.pdf&quot;&gt;this paper&lt;/a&gt;. Ventilation can be expressed in &quot;outside air changes/hour&quot;, or how often the total volume of air is replaced by new air. Airplanes have 10-15 changes/hour (every 4-6 minutes), which is 2-3 times more changes/hour than hospital delivery and operating rooms, and 4-15 times more than a typical building. New air is constantly being circulated into the cabin, while old air escapes through relief valves.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-01T14:55:29.620" LastActivityDate="2014-10-01T14:55:29.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8855" PostTypeId="2" ParentId="8852" CreationDate="2014-10-01T14:47:50.350" Score="11" Body="&lt;p&gt;In practical terms, no. If you wanted to save/recover the dumped fuel then you would have only two basic options: dump the fuel as usual and then recover it somehow from the air; or, pump the fuel in a controlled way into a container outside the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first option is probably impossible: how could you capture a huge cloud of fuel and fuel vapor mixed with the air? That would be like gathering water from clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second is theoretically possible, but for civil aviation at least it probably requires too much equipment and risk. You could pump the fuel into a drop tank then jettison it with a parachute for a soft landing. Or you could pump the fuel into another aircraft via a tube, in a kind of reverse air-to-air refuelling. Or if you're dumping fuel from a  helicopter (does that ever happen?) it could hover over a tank on the ground, pump out the fuel and then land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But all of those suggestions are totally impractical (again, at least for civil aviation). Adding drop tanks or air-to-air hoses would add huge cost in materials and training and reduce the useful load of the aircraft significantly, all for a situation that rarely occurs. And for air-to-air pumping you would need an empty tanker aircraft to be available immediately, which is highly unlikely, plus there is the inherent danger of operating two aircraft very close together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since fuel dumping is an exceptional situation and many aircraft &lt;a href=&quot;http://en.wikipedia.org/wiki/Fuel_dumping#Aircraft_fuel_dump&quot;&gt;can't dump fuel anyway&lt;/a&gt;, it seems unlikely that investing in a recovery solution would be worthwhile.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-01T14:47:50.350" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8856" PostTypeId="2" ParentId="8852" CreationDate="2014-10-01T15:10:48.267" Score="5" Body="&lt;p&gt;By conserve you mean collect for later use I am assuming. While it is technically feasible to do that it is extremely impractical. You'd have to either have another aircraft fly in formation in some sort of reverse in-air refueling system, or the pilots would need to fly over a system on the ground which would collect the fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any system to do this would require precision on the part of the aircraft needing to dump fuel, and in the kind of emergency where dumping fuel is required precision is one thing you aren't likely to get. Also, the cost of implementing a collection system far outweighs the cost of the fuel you'd save. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-01T15:10:48.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8858" PostTypeId="2" ParentId="8851" CreationDate="2014-10-01T16:11:42.973" Score="10" Body="&lt;p&gt;Blades of wind turbines, airplanes and helicopters are essentially the same. They are all wings, roughly to do the same job. However, each one is designed or enhanced to do their special job. The differences can be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Number of revolutions&lt;/li&gt;&#xA;&lt;li&gt;Wing span&lt;/li&gt;&#xA;&lt;li&gt;Rate of flow&lt;/li&gt;&#xA;&lt;li&gt;Tip speed&lt;/li&gt;&#xA;&lt;li&gt;Density of medium&lt;/li&gt;&#xA;&lt;li&gt;Material&lt;/li&gt;&#xA;&lt;li&gt;Load&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Turbine blades are designed to move in large volumes of rather slow moving air (usually 10-30 mph, 16-50 km/h) and not create turbulence that fouls the next blade. Aircraft propellers are designed to move high velocity air and avoid the turbulence by moving out of the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind turbines use blade pitch to adjust the rotation speed and the generated power. Wind turbine's control system adjusts the blade pitch to keep the rotor speed within operating limits as the wind speed changes. In aircraft, blade pitch is usually described as &quot;coarse&quot; for a coarser angle, and &quot;fine&quot; for a finer.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="33175" LastEditDate="2018-07-16T16:43:24.710" LastActivityDate="2018-07-16T16:43:24.710" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="8859" PostTypeId="2" ParentId="8852" CreationDate="2014-10-01T18:21:16.730" Score="8" Body="&lt;p&gt;In theory it could be done, you could rapidly dump fuel into empty tanks below the wings and drop them. At a certain height they deploy Parachutes and land. Just like the Space Shuttle ejects the side tanks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But where? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some fuel dumps are only authorized over water and it would cost more to rescue the tanks and bring them back to the airline. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over land they'd probably smash into populated areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost for saving some thousands of $ of fuel is not fesable for the rescue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer yeah it could be possible, but dangerous and costly.&lt;/p&gt;&#xA;" OwnerUserId="1732" LastEditorUserId="97" LastEditDate="2014-10-29T01:10:20.020" LastActivityDate="2014-10-29T01:10:20.020" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8860" PostTypeId="1" CreationDate="2014-10-01T18:26:47.680" Score="12" ViewCount="3787" Body="&lt;p&gt;The first photo in this &lt;a href=&quot;http://www.theverge.com/2014/9/30/6873473/a-five-airbus-formation-flight-is-as-beautiful-and-crazy-as-it-sounds&quot;&gt;article&lt;/a&gt; appears to depict three Airbus A350s flying closely in tandem at approximately the same altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought that a large jetliner would leave a trail of wake turbulence behind it that would be unsafe for several minutes.  Is there something special about the Airbus A350 that makes this formation possible?  Am I misinterpreting the photo?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The V formation in the second photo seems much more reasonable.&lt;/p&gt;&#xA;" OwnerUserId="487" LastActivityDate="2015-05-26T15:13:03.610" Title="How are these Airbus A350s flying in formation without being affected by wake turbulence?" Tags="&lt;wake-turbulence&gt;&lt;airbus-a350&gt;&lt;flying-in-formation&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8861" PostTypeId="2" ParentId="8860" CreationDate="2014-10-01T18:34:37.907" Score="9" Body="&lt;p&gt;You are right that wake turbulence would be a danger when flying behind another aircraft like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The perspective of the photo makes it hard to see the actual position of the trailing aircraft relative to the ones in front of it. Pilots do this sort of thing in airshows when they fly in formation. The trailing aircraft are generally slightly below the ones in front of it. This allows good visibility of the plane they are following. At the higher speeds that these jets are flying at, the wake vortex will not drop enough to impact an aircraft fairly close behind and below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this old photo of the Thunderbirds. From this perspective, it is easier to see that the trailing aircraft is also below the flight path of the leading aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/heBqD.jpg&quot; alt=&quot;Thunderbirds in formation&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-01T20:15:08.307" LastActivityDate="2014-10-01T20:15:08.307" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8863" PostTypeId="2" ParentId="8860" CreationDate="2014-10-01T19:21:30.340" Score="8" Body="&lt;p&gt;Yes, it does appear that the airplanes behind the lead in a formation would be affected by wake turbulence. In reality, there are several factors which contribute to make it not so risky.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Airplanes make the formation on high altitudes. Wake Turbulence becomes a bigger issue during takeoff and landing phases. As mentioned on &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake_turbulence&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wake turbulence is especially hazardous in the region behind an&#xA;  aircraft in the takeoff or landing phases of flight. During take-off&#xA;  and landing, aircraft operate at high angle of attack. This flight&#xA;  attitude maximizes the formation of strong vortices. In the vicinity&#xA;  of an airport there can be multiple aircraft, all operating at low&#xA;  speed and low height, and this provides extra risk of wake turbulence&#xA;  with reduced height from which to recover from any upset.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Wake turbulence travels like this (&lt;a href=&quot;http://www.pilotfriend.com/safe/safety/wake_turb.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/411YC.jpg&quot; alt=&quot;Wake Turbulence&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, based on weather and wind, the following airplanes &lt;em&gt;would&lt;/em&gt; know what should be their best position in reference to the lead. They avoid this situation (&lt;a href=&quot;http://www.ahrtp.com/RSS-JSfeeds/AF_447_composites_tail_hypercomplexity-6E.html#587.wake&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3KBPs.jpg&quot; alt=&quot;Caught in wake turbulence&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airplanes in formation do not fly on the same altitude but are either slightly above or below the lead. This is very hard to figure out when you are watching from ground, or in several pictures. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-05-26T15:13:03.610" LastActivityDate="2015-05-26T15:13:03.610" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8864" PostTypeId="1" AcceptedAnswerId="8879" CreationDate="2014-10-01T20:04:59.440" Score="15" ViewCount="5261" Body="&lt;p&gt;There are a couple of questions about the emergency procedure of fuel dumping, used to reduce the weight of airplanes to be able to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is certainly interesting, regarding environmental affects, safety aspects, and maybe some archaic fascination for huge fuel-air clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How relevant these questions really are depends on &lt;strong&gt;how often&lt;/strong&gt; fuel dumping is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I don't know how often it is actually done, in incidents per year globally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the procedure is used only in emergency cases, but &lt;strong&gt;not only&lt;/strong&gt; in very few very &lt;strong&gt;extreme&lt;/strong&gt; situations. It's about getting the weight down to be able to land safely, and the overweight is from fuel not yet used up on the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the procedure is needed whenever there is a need to urgently land, and there is not enough time to burn the fuel in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That seems to mean that severe medical emergencies of individual passengers may be a reason? That happens much more often than drastic technical problems I assume, so it would be a strong factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I'm interested in some rough &lt;strong&gt;total estimate&lt;/strong&gt; about how often fuel dumping happens, and the main factors, like &lt;strong&gt;minimal emergency cases&lt;/strong&gt; that can lead to a fuel dump.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd simplify the scope by considering only commercial aviation, ignoring military and general aviation - but I do not see that as important, use the data you have at hand.&lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="1875" LastEditDate="2018-08-23T11:06:42.060" LastActivityDate="2018-08-23T11:06:42.060" Title="How often does fuel dumping from planes in flight actually occur?" Tags="&lt;landing&gt;&lt;commercial-aviation&gt;&lt;emergency&gt;&lt;weight-and-balance&gt;&lt;fuel-dumping&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8865" PostTypeId="1" AcceptedAnswerId="8873" CreationDate="2014-10-01T20:37:36.280" Score="7" ViewCount="1980" Body="&lt;p&gt;Most aircraft have horizontal tails. What is the advantage of increasing the horizontal tail surface area?&lt;/p&gt;&#xA;" OwnerUserId="3319" LastEditorUserId="3170" LastEditDate="2015-04-22T02:53:05.553" LastActivityDate="2015-04-22T11:47:25.590" Title="What is the advantage of increasing an aircraft's horizontal tail surface area?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8866" PostTypeId="1" AcceptedAnswerId="8867" CreationDate="2014-10-01T20:59:28.770" Score="6" ViewCount="1087" Body="&lt;p&gt;Excluding various first-class seating arrangements, are there any examples in history or today, of an airline that has implemented a non-standard seating arrangement?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, most military transport aircraft contain just rows with passengers' shoulders inline with the bow and aft. Are there any examples of where a commercial airline has tried this arrangement -or any other type?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An extreme example would be an airline like a subway car (everyone standing up, just hanging on to something).&lt;/p&gt;&#xA;" OwnerUserId="3699" LastEditorUserId="13197" LastEditDate="2016-03-01T21:31:28.570" LastActivityDate="2016-03-01T21:31:28.570" Title="Are there examples (current or historical) of commercial aircraft seating arrangments beyond the standard today?" Tags="&lt;airline-operations&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8867" PostTypeId="2" ParentId="8866" CreationDate="2014-10-01T21:31:30.170" Score="5" Body="&lt;p&gt;Some of the old flying boats had a seemingly haphazard arrangement&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/52PG2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/iwOJB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://socks-studio.com/2010/11/07/flying-boats/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NNb02.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.seattlepi.com/business/boeing/article/Things-people-leave-on-airplanes-3720648.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BMYvp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://es.wikipedia.org/wiki/Dornier_Do_X&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But maybe all flying boat passengers were effectively first class?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-01T21:59:47.480" LastActivityDate="2014-10-01T21:59:47.480" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8869" PostTypeId="1" AcceptedAnswerId="8871" CreationDate="2014-10-01T21:55:39.270" Score="12" ViewCount="2728" Body="&lt;p&gt;I am a 24 year old who has always aspired to become a pilot. I've decided to eventually get a private pilot's license so I can fly just for fun. However, a few months ago I was diagnosed with brain tumor which I had removed. There were no complications, I have never had any seizures, I'm not epileptic, etc. As far as I am concerned (and my doctors as well), I am now in perfect health.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With this in mind, is it still possible for me to obtain a PPL?&lt;/p&gt;&#xA;" OwnerUserId="3720" LastEditorUserId="62" LastEditDate="2014-10-01T23:02:52.993" LastActivityDate="2020-11-20T17:39:43.863" Title="Is it possible to obtain a PPL after having a brain surgery?" Tags="&lt;faa&gt;&lt;medical&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8870" PostTypeId="2" ParentId="8852" CreationDate="2014-10-01T21:55:45.237" Score="4" Body="&lt;p&gt;I suppose the least expensive way to do it would be to reinforce the airplane structure so that it coud land at maximum takeoff weight. Then no dumping would ever need to occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still not cheap enough to be practical, though. The weight of that extra structure would take fuel to carry around at all times, to save fuel only on the rare emergency.&lt;/p&gt;&#xA;" OwnerUserId="747" LastActivityDate="2014-10-01T21:55:45.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8871" PostTypeId="2" ParentId="8869" CreationDate="2014-10-01T23:02:35.660" Score="18" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.aopa.org/&quot;&gt;AOPA&lt;/a&gt;'s medical guru on their discussion board (members only, or I would link to an example) it is possible to get a medical certificate following a tumor removal but only after a 5-year wait and a battery of tests.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But having said that, medical issues are very individual and the FAA's &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item46/amd/cd/&quot;&gt;AME guidance&lt;/a&gt; suggests that one year is enough in some cases. In the end the only way to get a definite answer is to find a good AME who can review your case in detail and advise you. Note that standard advice is to schedule a consultation first, rather than go straight for the actual flight medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I'm not a doctor or AME and I have no idea how brains work :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-01T23:02:35.660" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8872" PostTypeId="2" ParentId="8869" CreationDate="2014-10-01T23:18:54.533" Score="4" Body="&lt;p&gt;If you are in the United States and you have never been denied an FAA medical certificate or had your medical revoked and you have a driver's license, then you can fly as a sport pilot in light sport aircraft.  There are some limitations compared to a PPL, the major ones being that you are limited to one passenger and daytime VFR operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you decide to later move up to a PPL, then you will have to get a medical.  There is some risk, though.  If you attempt to get a medical and are denied, you will also lose your sport pilot priviliges.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2014-10-01T23:18:54.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8873" PostTypeId="2" ParentId="8865" CreationDate="2014-10-02T05:01:07.707" Score="7" Body="&lt;p&gt;Increasing horizontal stabilizer area increases pitch stability and the permissible range for centre of gravity at the cost of some aerodynamic efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stability in pitch means that the aircraft tends to maintain constant angle of attack (which roughly corresponds to maintaining constant speed with pitch). An aircraft is stable in pitch if the aft surface flies at lower angle of attack than the front surface (this applies to both conventional tails and canards).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making the horizontal stabilizer larger does the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The absolute change in lift force on the horizontal stabilizer when angle of attack changes is larger, so the aircraft returns to the trimmed angle of attack faster (increased stability).&lt;/li&gt;&#xA;&lt;li&gt;As centre of gravity moves aft, the difference in angle of attack between the surfaces decreases to keep the plane balanced, reducing pitch stability. If the horizontal stabilizer is larger, the angle of attack changes more slowly for the same change in lift, so the centre of gravity may be permitted further aft before the aircraft becomes not stable enough.&lt;/li&gt;&#xA;&lt;li&gt;As centre of gravity moves forward, the difference of angle of attack between the surfaces increases until angle of attack of the horizontal stabilizer exceeds its stall angle of attack and control is lost. If the horizontal stabilizer is larger, it can provide more (downward!) lift before it stalls, so the centre of gravity can be permitted further forward before loosing control authority.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-04-22T11:47:25.590" LastActivityDate="2015-04-22T11:47:25.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8874" PostTypeId="2" ParentId="8866" CreationDate="2014-10-02T05:52:43.110" Score="4" Body="&lt;p&gt;Current FAA passenger safety regulations require seats with 16G survivability:&#xA;&lt;a href=&quot;http://www.faa.gov/passengers/fly_safe/safety_improvements/media/FAA-FactSheet-Aircraft-Survivability.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/passengers/fly_safe/safety_improvements/media/FAA-FactSheet-Aircraft-Survivability.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the PDF notes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1988, the FAA issued regulations&#xA;  requiring that all newly developed&#xA;  transport aircraft use “16g” seats.&#xA;  Using a test dummy, these seats&#xA;  undergo dynamic testing and&#xA;  evaluation regarding injury&#xA;  protection. Similar to automobile&#xA;  crash tests, the FAA tests are&#xA;  designed specifically for the aviation&#xA;  environment. Previously, seats were&#xA;  designed and approved to a static&#xA;  9g standard with no occupant&#xA;  injury criteria. Most transport&#xA;  airplanes were developed before&#xA;  1988. However, Amendment&#xA;  121-315, effective October 27,&#xA;  2005, required that transport&#xA;  category airplanes in part 121&#xA;  operations, certificated after&#xA;  January 1, 1958 and manufactured&#xA;  on or after October 27, 2009, must&#xA;  comply with the 16g dynamic&#xA;  standard. In 2010, the agency&#xA;  published guidance on the&#xA;  importance of analyzing how interior&#xA;  structures, such as seats, interact&#xA;  with other structures due to critical&#xA;  loads. In July 2012, the FAA issued&#xA;  new criteria for side-facing seats&#xA;  that are equivalent to the occupant&#xA;  protection for standard&#xA;  forward-facing seats&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is very hard to design side-facing seats that meet these survivability standards (human necks are very weak in the lateral direction). Furthermore, the airplanes are current designed with seats that slide on tracks in order to make the cabins easily customizable to customer (airplane company) requirements. This also makes it easier to design around front-facing seats:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EgwNn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And let us not forget this quickly abandoned proposal. Everyone would still be facing forward but we'd be standing! With shoulder and waist harnesses (five point), survivability might actually be pretty good! Actually, I'd want a head and neck retainer too. :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wXoJ0.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2014-10-03T18:25:52.897" LastActivityDate="2014-10-03T18:25:52.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8875" PostTypeId="1" AcceptedAnswerId="8876" CreationDate="2014-10-02T07:55:31.590" Score="7" ViewCount="1373" Body="&lt;p&gt;Based on any historical records, who has been the oldest pilot ever? &quot;Pilot&quot;, I mean, somebody who managed to take off, return to the airport and land without  help. That much is probably not possible without training; would still be interesting to know if this pilot had a valid or maybe expired license.&lt;/p&gt;&#xA;" OwnerUserId="917" LastActivityDate="2014-10-02T13:35:59.730" Title="Who was the oldest pilot ever so far?" Tags="&lt;pilots&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8876" PostTypeId="2" ParentId="8875" CreationDate="2014-10-02T09:05:05.553" Score="10" Body="&lt;p&gt;&lt;strong&gt;Cole Kugel, 105&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Born March 14, 1902, Cole Kugel, a resident of Longmont, Colorado, USA is the oldest qualified pilot. He was born one year before the legendary Wright Brothers took to the skies, and has been flying ever since. Kugel earned his pilot's license in 1945 and flew in 2007 for the last time, aged 105, piloting in the company of local veterinarian Lynn Ferguson in his beloved 1976 Cessna 182.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.guinnessworldrecords.com/records-1000/oldest-qualified-pilot/&quot; rel=&quot;noreferrer&quot;&gt;http://www.guinnessworldrecords.com/records-1000/oldest-qualified-pilot/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.denverpost.com/business/ci_6134939&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CzSY9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;2005 Photo: Daily Times-Call | Hunter McRae&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-02T13:35:59.730" LastActivityDate="2014-10-02T13:35:59.730" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8877" PostTypeId="1" AcceptedAnswerId="8882" CreationDate="2014-10-02T13:40:29.123" Score="39" ViewCount="10567" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8860/how-are-these-airbus-a350s-flying-in-formation-without-being-affected-by-wake-tu&quot;&gt;This question&lt;/a&gt; discusses how wake turbulence can affect planes flying in formation.  It got me wondering, how do aircraft (the wings in particular) form wake turbulence to begin with?  It can't be as simple as tip vortexes right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a follow up, how can you design an aircraft to minimize wake turbulence?  And what are the trade offs in doing so? &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-02-16T19:45:55.190" Title="How does an aircraft form wake turbulence?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;wake-turbulence&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8878" PostTypeId="2" ParentId="8864" CreationDate="2014-10-02T13:49:12.030" Score="4" Body="&lt;p&gt;In commercial aviation fuel is dumped rarely.  Only if the aircraft is taking off above max landing weight and an emergency takes place shortly after takeoff would a commercial aircraft be required to dump fuel.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military cargo aircraft have max landing weights similar to their max takeoff weights, so they also rarely dump fuel.  Military tanker aircraft are probably the most likely to dump fuel as their max takeoff weight is well above their max landing weight.  In this case, two scenarios would drive dumped fuel - 1) An emergency condition that will require the aircraft to land prematurely within the first couple hours of flight 2) the loss of receiver aircraft driving a condition where it would be more efficient to dump fuel and land rather than fly until the fuel is low enough.  This probably occurs once a week.  I'd probably estimate that all of commercial aviation dumps about as much as the US tanker fleet, but that is just a wag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the fuel clouds, the altitudes where fuel is intentionaly dumped are high enough so that the fuel quickly disperses and is not an environmental factor.  Furthermore, there are prescribed dump locations which are located away from populated areas.&lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2014-10-02T13:49:12.030" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8879" PostTypeId="2" ParentId="8864" CreationDate="2014-10-02T14:44:34.883" Score="10" Body="&lt;p&gt;These &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a306554.pdf&quot;&gt;two&lt;/a&gt; &lt;a href=&quot;http://www.researchgate.net/profile/Harvey_Clewell/publication/236659290_Ground_Contamination_by_Fuel_Jettisoned_from_Aircraft_in_Flight/links/0c960518bdf144a6e4000000&quot;&gt;reports&lt;/a&gt; cite that the US Air Force at one time jettisoned fuel nearly 1000 times per year. The second report also mentions that commercial airlines reported 485 instances of fuel jettison over a 5 year period. The commercial reports are only for maintenance related cases though, not including scheduling or weather reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both of these figures date from the 1970s. Military standards have been changed since then to reduce the frequency of it. The first paper assumed that in 1995, military fuel jettisoning was &quot;infrequent&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-02T14:44:34.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8880" PostTypeId="2" ParentId="8877" CreationDate="2014-10-02T15:14:51.703" Score="26" Body="&lt;p&gt;It is as simple as &quot;tip&quot; vortices, but that is a misnomer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing vortices are not really caused by the &quot;tips&quot;. They are inherent effect of generating lift over finite wingspan. To generate lift (a force on the plane), the aircraft applies force on the surrounding air (by Newton's third law). Since the air is free to move, this force accelerates it (according to Newton's second law) downward. Due to the way fluids work the force affects air both above and below the wing (to height comparable to wingspan), but not to the sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://www.av8n.com/how/img48/trailing.png&quot; alt=&quot;Wing vortex ring; from the excellent online book &amp;quot;How It Files&amp;quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So directly behind the plane we have air that is moving down and on the sides air that remains still. And this is the wing vortices. See also &lt;a href=&quot;https://www.av8n.com/how/&quot; rel=&quot;noreferrer&quot;&gt;John S. Denker: How It Flies&lt;/a&gt;, &lt;a href=&quot;https://www.av8n.com/how/htm/airfoils.html#sec-circulation-vortices&quot; rel=&quot;noreferrer&quot;&gt;section 3.14&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is slight updraft just outside the wingtips caused by the transverse flow around the wing tip, but it only contributes a tiny fraction (at most couple of percent) of the circulation and associated drag. There is also some turbulence caused by simply moving through the air at sufficient speed, but that is comparably minor as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inertia the aircraft has to impart to the air over unit of time is proportional to the aircraft weight. Therefore turbulence behind heavier aircraft is stronger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft flies faster it affects more air per unit of time, so it suffices to accelerate it to lower speed. Therefore turbulence behind slower flying aircraft (e.g. during take-off or landing) is stronger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft flies higher the air is less dense (has lower mass per unit of volume) so it needs to be accelerated to higher speed. Therefore turbulence behind aircraft flying higher is stronger. Fortunately when flying high aircraft also fly fast.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.037" LastActivityDate="2014-10-02T16:23:36.990" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8882" PostTypeId="2" ParentId="8877" CreationDate="2014-10-02T21:29:35.033" Score="30" Body="&lt;p&gt;&lt;strong&gt;Origin of the vortices&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wake turbulence is easy to understand once you know how a wing creates lift: By deflecting the air flowing across it downwards. In &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;this answer&lt;/a&gt;, I had used the simplification of just accelerating downwards all the air flowing through a circle with a diameter equal to the wingspan, and leaving all other air unaffected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This helps to understand the principle of lift creation, but is too simple, of course, because the downward movement of air will create a void above it, and the air below has to make place for that downward moving streamtube. Also, the pressure field around the wing will affect the air in the vicinity of the streamtube as well, and in consequence air from below will be pushed sideways already by the wing, and the air above will start to flow towards the low pressure area over the wing. This sideways movement will become more pronounced aft of the wing, such that air will continuously be pressed outwards below the wing's wake, move up left and right of it and inwards above the wake. The inertia of the downwash keeps it moving downwards for several minutes, continuously displacing the air below it and sucking more air into the space above, and that will result in two vortices swirling behind the wing. This is the rolling up of the wake (see the sketch below, taken from &lt;a href=&quot;http://www.airpower.maxwell.af.mil/airchronicles/aureview/1971/jul-aug/carten.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cvizJ.jpg&quot; alt=&quot;roll-up of wake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vortices are just a consequence of the downward movement of the wake, and this in turn is a consequence of lift creation. Please note that the cores of the vortices are closer together than the wingspan! This by itself should make clear that they are not caused by air flowing around wingtips, a hard to extinguish misconception. The table below gives calculations of this vortex spacing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WruGU.jpg&quot; alt=&quot;table of vortex characteristics&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The table is also from the &lt;a href=&quot;http://www.airpower.maxwell.af.mil/airchronicles/aureview/1971/jul-aug/carten.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carten paper of 1971&lt;/a&gt;; note the inclusion of Boeing's 2707 project!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Strength of the vortices&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we again come back to the simplified streamtube approximation, lift is proportional to the mass of air flowing through it per unit of time times the deflection angle. If lift is equal to the aircraft's mass (as it should be), heavy aircraft need to either accelerate more air (wider span) or accelerate air more (higher deflection angle) than light aircraft at the same speed. A higher deflection angle will produce more powerful vortices. For that reason, a heavy aircraft at low speed and with a small wingspan will produce the strongest vortices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since more air flows through the streamtube at higher flight speed, flying faster will require less deflection, making the wake vortices weaker. If the aircraft climbs, air becomes less dense with altitude, and less mass flow over the wing is available, so the vortices grow stronger if the flight speed does not change. Normally, aircraft accelerate when climbing, and the vortex strength will stay the same if the aircraft flies at constant dynamic pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortices can be avoided in three ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Infinite wing span (meaning infinite mass flow, so no deflection is necessary for any lift)&lt;/li&gt;&#xA;&lt;li&gt;Infinite speed (again, gives infinite mass flow)&lt;/li&gt;&#xA;&lt;li&gt;No weight of the aircraft. Flying a zero-g parabola does indeed produce almost no wake turbulence.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;End of the vortices&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inertia will keep the wake moving downwards and the vortices spinning, but friction will let those air movements die down within a few minutes. If the aircraft flies high, the wake is dissipated long before it hits the ground. The wake of low flying aircraft, however, does hit the ground and is deflected. The vortex tube now acts like a wheel and starts moving outward, and if there is a sufficient crosswind, the windward vortex can be arrested as in the right sketch below (also from the Carten report).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dvoF7.jpg&quot; alt=&quot;Interference with ground&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Photographic evidence&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are far too &lt;a href=&quot;http://kitskinny.wordpress.com/2013/07/09/jets-clouds-effects/&quot; rel=&quot;nofollow noreferrer&quot;&gt;many pretty pictures around of wake vortices&lt;/a&gt; to not include some, so I will add a few here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O6Fn5.jpg&quot; alt=&quot;B-747 with contrails&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that the outer contrails of this Boeing 747's engines wrap around the contrails of the inner engines. This shows how the air is pushed down in the wake of the wing and that the centers of the vortices are slightly inboard of the outer engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyr0c.jpg&quot; alt=&quot;A-340&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The condensation traces originating at the winglet tips of this A340 move in- and upward, again showing that the vortex does not originate from the tips but forms behind the wing and with a distance between the two vortex cores of substantially less than the wingspan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oS0oX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These two pictures show how the downwash of the wake is cutting a furrow in the clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SBR99.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SBR99.jpg&quot; alt=&quot;MD-11 on a moist day&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;KLM MD-11 on a moist day, flaps set for landing (&lt;a href=&quot;https://www.airliners.net/photo/KLM-Royal-Dutch-Airlines/McDonnell-Douglas-MD-11/705013?qsp=eJyrVkrOzytJrSgJqSxIVbJSSsxJKs1V0lEqSCxKzC1WsqqGiHimKFlZWFqa19YCALEmELY%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt; © Erwin van Dijck). One, it shows how insignificant the tip vortex is compared to vorticity shed at the flap tips, and Two it shows how the tip vortex moves inward and starts to be sucked into the wake vortex. Note also the tip vortices from the tail!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-02-16T19:45:55.190" LastActivityDate="2020-02-16T19:45:55.190" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="8883" PostTypeId="2" ParentId="8730" CreationDate="2014-10-02T21:37:02.177" Score="2" Body="&lt;p&gt;Have you seen Flight Aware's &lt;a href=&quot;http://flightaware.com/commercial/flightxml/&quot; rel=&quot;nofollow&quot;&gt;Flight Status API&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerDisplayName="user3725" LastEditorUserId="97" LastEditDate="2015-05-03T00:51:25.883" LastActivityDate="2015-05-03T00:51:25.883" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8884" PostTypeId="1" CreationDate="2014-10-03T02:34:35.960" Score="5" ViewCount="242" Body="&lt;p&gt;With so many factors that could affect performance (wind, visibility range (amount of light), angle of the sun, etc.), how do they accurately test solar aircraft flight time? Any tips for doing my own experiment for a small solar RC plane (vs non-solar of same type)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for any help!&lt;/p&gt;&#xA;" OwnerUserId="3728" LastEditorUserId="1696" LastEditDate="2015-04-22T17:14:15.280" LastActivityDate="2015-04-25T03:57:21.480" Title="How are performance variables accounted for when testing solar-powered aircraft?" Tags="&lt;aircraft-performance&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8885" PostTypeId="1" AcceptedAnswerId="8889" CreationDate="2014-10-03T04:42:09.707" Score="10" ViewCount="14537" Body="&lt;p&gt;Related to this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/8784/do-military-pilots-have-flight-rest-hours-regulation&quot;&gt;Do military pilots have flight &amp;amp; rest hours regulation?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://en.wikipedia.org/wiki/History_and_culture_of_substituted_amphetamines#Military_use&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia article&lt;/a&gt;, amphetamines were commonly given to Allied pilots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they still in use today?&lt;/p&gt;&#xA;" OwnerUserId="3049" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-10-03T12:57:31.970" Title="Do military pilots use amphetamines or other stimulants?" Tags="&lt;military&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8887" PostTypeId="1" AcceptedAnswerId="8888" CreationDate="2014-10-03T11:12:45.557" Score="3" ViewCount="931" Body="&lt;p&gt;What is the maximum range of a BAe 146-300? I saw one on Flightradar24.com which started in western France and is still flying non-stop to Greece (flight in progress at the time of posting).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was really surprised, I guess they probably have an additional fuel tank? I know that some airlines do add extra tanks  to their planes (e.g. on a &lt;a href=&quot;http://www.b737.org.uk/fuel.htm#Auxiliary_Fuel_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;B737&lt;/a&gt;) to increase the maximum range; but is it possible on on a BAe 146-300?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OxuPU.jpg&quot; alt=&quot;Flightradar24.com Screenshot&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="97" LastEditDate="2015-05-03T00:48:21.333" LastActivityDate="2015-05-03T00:48:21.333" Title="What is the maximum range of a BAe 146-300? Can auxiliary fuel tanks be added?" Tags="&lt;fuel-tanks&gt;&lt;range&gt;&lt;bae-146&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8888" PostTypeId="2" ParentId="8887" CreationDate="2014-10-03T11:38:29.577" Score="8" Body="&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Aerospace_146#Specifications_.28BAe_146-200.29&quot; rel=&quot;noreferrer&quot;&gt;wikipedia&lt;/a&gt; it has a range of 2909 km and the distance is around 2500 km&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nDloD.png&quot; alt=&quot;google maps measuring FTW&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-03T11:38:29.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8889" PostTypeId="2" ParentId="8885" CreationDate="2014-10-03T12:57:31.970" Score="12" Body="&lt;p&gt;The U.S. Air Force (and Navy) still uses, and has used off and on since WWII,  what are commonly referred to as &quot;Go Pills&quot; for instances when pilots need to be up for long periods of time - in wartime, sometimes longer than the crew rest regulation. (These pills can also be used for altering sleep cycles, along with &quot;no-go&quot; pills; for example, when changing from day to night).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most common go pill is &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Dextroamphetamine&quot;&gt;Dexedrine&lt;/a&gt;, which is an amphetamine. You can find some more information in &lt;a href=&quot;http://www.nbcnews.com/id/3071789/ns/us_news-only/t/go-pills-war-drugs/&quot;&gt;this article&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-10-03T12:57:31.970" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8890" PostTypeId="1" CreationDate="2014-10-03T13:25:00.517" Score="4" ViewCount="1238" Body="&lt;p&gt;I understand the archimedes principle as it relates to water, but am having trouble reconciling a thesis related to a hot air balloon.  If theoretically, I could increase the temperature of air contained in a fixed pocket/container, would the increased pressure exerted upward lift the container?  The archimedes principle would argue against the prospect of lifting the container due to the fact that the container remains the same size and therefore displaces the same amount of air outside.  However, I find it difficult to understand why increased upward pressure on the container would not lift the container.  Can you explain? &lt;/p&gt;&#xA;" OwnerUserId="3736" LastActivityDate="2014-10-06T02:59:34.020" Title="if temperature is increased but the volume contained in a area, will an air balloon lift?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8891" PostTypeId="1" AcceptedAnswerId="8926" CreationDate="2014-10-03T13:31:15.563" Score="9" ViewCount="19041" Body="&lt;p&gt;&lt;strong&gt;I am 19 years old and from a young age I have always wanted to become a pilot at an airline. Becoming one is my biggest dream, to me an airline pilot is the most coolest jobs - I get goosebumps just by thinking about me in that position.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have finished my high school education and hope to go to Australia to study in order to become a pilot. However, most of the university programs don't give me the feeling that I can become a pilot. Most of what is learned and practiced is in small planes, even the career opportunities don't mention that one will become an airline pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know the best and fastest way to make my dream come true? What should I do?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The only course that has got me attracted to is the one that's in Swinburne University, but then again, &lt;strong&gt;small planes&lt;/strong&gt;. I am fine with flying small planes, but where does that big jump to airplanes happen, if it's not taught in university. Where do I learn it? Does anyone know the procedure or the best place to train to become a pilot?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Also, I'm not an Australian so I will be an international student. I have checked for jobs in my home country airlines, they require a minimum of 5000 hours of flight, does this mean normal plane flight hours? Where will I get these hours covered from? Of course this many hours aren't offered in university. &lt;/p&gt;&#xA;" OwnerUserId="3735" LastEditorUserId="753" LastEditDate="2018-03-12T08:43:45.637" LastActivityDate="2021-04-21T07:09:21.287" Title="How does one become an airline pilot in Australia?" Tags="&lt;commercial-aviation&gt;&lt;career&gt;&lt;australia&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8892" PostTypeId="2" ParentId="8884" CreationDate="2014-10-03T13:42:56.130" Score="5" Body="&lt;p&gt;Usually when test results are potentially affected by many factors, standard test conditions are defined. When tests are performed under these standard conditions, the results can be compared between products.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since these standard conditions rarely exists in nature, testing under standard conditions is not possible. Instead, a test programme is developed that tests under a number of non standard conditions to identify the effect of individual factors and correct for that. In addition, components of the system under test can often be tested in an isolated controlled environment. In this way, standard conditions can be achieved for individual components and the effect of deviations for the standard conditions can be determined as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the example of a solar aircraft, the efficiency of the solar panels could be determined independent of the aircraft. The same holds for the battery, the engine, the propeller and other components that the propulsion system may depend on. Not only the performance under standard conditions can be determined, but also under non-standard conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power requirements of the aircraft under a range of conditions can be determined by test flights. This could involve horizontal cruise flight segments at various speeds, altitudes and temperatures, and also gliding tests. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum achievable flight time under standard and non-standard conditions can then be calculated from the results of all the acquired test results, without ever having flown under these standard conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For validation of the methodology used, a test flight can be done do determine the actual flight time under non-standard conditions. When the results of the test flight agree with the calculated flight time under the same non-standard conditions, one can assume that the methodology is correct. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For you own RC plane such a test programme is probably out of scope. A simple way to gather some data is to perform two flights with the same aircraft. Both time start with a full charge (I assume there is a battery involved). Test how long the flight last with the solar panels. For the second flight, disconnect the panels and see how long the flight last then. You now know how much the solar panels contribute in terms of power production. Then fly with the non-solar plane and see how long that lasts. It will probably last longer than the solar plane with the panels disconnected because it doesn't have to carry the extra weight of the panels. This way you learn what the addition of solar panels costed in terms of flight efficiency. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-03T13:42:56.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8894" PostTypeId="2" ParentId="8890" CreationDate="2014-10-03T13:50:15.277" Score="11" Body="&lt;p&gt;I case of an hot air balloon, the volume of the balloon remains unchanged when the air is heated. But because the heated air expands, part of it escapes from the balloon since it is not closed (the bottom is open). Therefore the weight of the air inside the balloon is reduced. The hot air in the balloon has a lower density that the cool air around it. Therefore the balloon lifts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XZ8mt.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would a closed balloon of unstretchable fabric be used, then the pressure in the balloon would rise but the volume of the balloon would remain unchanged. Therefore the density of the air inside the balloon and the buoyancy would remain the same and the balloon would not lift off. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-03T21:20:35.183" LastActivityDate="2014-10-03T21:20:35.183" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8895" PostTypeId="2" ParentId="8890" CreationDate="2014-10-03T14:11:55.153" Score="5" Body="&lt;p&gt;When you increase the pressure in a closed volume, the increase pressure will act on all parts of the surface. Since both the upward-facing and the downward-facing area is the same, those pressures cancel each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to reduce the area on the lower end of the volume, you need to cut a hole in it. Now the upper area is bigger by the area of the hole, and the volume will be forced upwards by a force which is the product of the pressure difference to  outside pressure and the area difference, which is the area of the hole. This kind of lift, however, is not buoyancy, but rocket thrust. Unfortunately, as soon as you open that hole, gas will flow out and the pressure difference will vanish, unless you pump more gas into the volume.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-03T14:11:55.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8897" PostTypeId="2" ParentId="8891" CreationDate="2014-10-03T14:19:51.467" Score="3" Body="&lt;p&gt;I'm not super sure about Australia, but in general terms, I know that it can take a lot of time to get from a regular license to being a commercial jet pilot.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first step is to get your private pilots license.  So I'd find a program to get that taken care of.  Then you're going to want to look for programs that get you a commercial rating (which simply means you'd have a license that allowed you to make money by flying a plane.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no real big jump at any point, you go from very small planes to progressively larger planes over a period of years.  In fact, when you first start flying commercial, it is likely that you will be flying a somewhat small aircraft for minor tasks.  Like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Beechcraft_King_Air&quot; rel=&quot;nofollow&quot;&gt;Beechcraft King Air&lt;/a&gt; or something similar.  From there you just build up more and more hours and get jobs with bigger and bigger carriers until one day you land that dream job of yours, flying 747s ;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some colleges will help you scoot the process along by getting you a bunch of hours in the smaller commercial aircraft (like the above mentioned King Air.)  But I don't know of any that will have you flying jet airplanes for a larger carrier the moment you graduate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, I'm not super familiar with colleges in Australia, so perhaps they are significantly different than colleges in the US (which is where I'm from.)&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-10-03T14:19:51.467" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8898" PostTypeId="2" ParentId="2021" CreationDate="2014-10-03T14:35:21.330" Score="4" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;What problems do cell-phones cause?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The FAA believes they could cause controlled flight into terrain.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Airlines have been ordered to replace or modify the cockpit display units fitted to hundreds of Boeing jets.&lt;/p&gt;&#xA;&lt;p&gt;The US air safety regulator said that tests had indicated that &lt;strong&gt;mobile phone&lt;/strong&gt; and computer signals could cause the screens to go blank.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;We are issuing this AD [airworthiness directive] to prevent loss of flight-critical information displayed to the flight crew during a critical phase of flight, such as an approach or take-off, which &lt;strong&gt;could result in loss of airplane control at an altitude insufficient for recovery, or controlled flight into terrain&lt;/strong&gt;,&amp;quot; it said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.bbc.co.uk/news/technology-29445385&quot; rel=&quot;nofollow noreferrer&quot;&gt;BBC&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-03T15:31:03.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8899" PostTypeId="1" CreationDate="2014-10-03T14:54:02.693" Score="15" ViewCount="2525" Body="&lt;p&gt;In &lt;a href=&quot;https://www.youtube.com/watch?v=i9IhQxmt08U&quot;&gt;this video&lt;/a&gt;, a 767 takes off in bad weather conditions. The comments of the video aren't very professional, so I ask here:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is this a legitimate takeoff?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some comments say that this was a close takeoff. Some comments do point out that on rotate, you can see the end of the strip of the lefter runway. Was it airborne before?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-10-03T15:12:11.053" LastActivityDate="2014-10-04T13:19:16.943" Title="Is this takeoff of a 767 in bad weather conditions a normal procedure?" Tags="&lt;weather&gt;&lt;boeing&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8900" PostTypeId="1" AcceptedAnswerId="8903" CreationDate="2014-10-03T15:13:14.413" Score="15" ViewCount="5383" Body="&lt;p&gt;How dangerous can it be if something falls from a flying aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3738" LastEditorUserId="572" LastEditDate="2015-02-19T09:01:12.300" LastActivityDate="2017-06-24T04:39:30.613" Title="How dangerous can it be if something falls from a flying aircraft?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;commercial-operations&gt;" AnswerCount="7" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8901" PostTypeId="2" ParentId="8900" CreationDate="2014-10-03T15:26:30.993" Score="6" Body="&lt;p&gt;Probably not, but it is possible that due to structural failure an &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_191#Engine_separation&quot; rel=&quot;noreferrer&quot;&gt;engine&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot; rel=&quot;noreferrer&quot;&gt;vertical stabilizer&lt;/a&gt; or the entire plane itself will fall down. Though often the plane will come down shortly after.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible that a small leak lets the &lt;a href=&quot;http://en.wikipedia.org/wiki/Blue_ice_%28precipitation%29&quot; rel=&quot;noreferrer&quot;&gt;waste of the toilet seep out and freeze to the fuselage which can let go and come down in a big chunk&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-03T15:26:30.993" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8902" PostTypeId="2" ParentId="8899" CreationDate="2014-10-03T15:26:55.713" Score="11" Body="&lt;p&gt;Take-off within the crosswind limits is a normal procedure. From the video it's hard to tell what the crosswind was in this particular situation, so it is impossible to tell about the legitimacy of this take-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotation seems to be on the 1000ft marker, i.e. 1000 ft from the runway threshold. But in case of a displaced threshold the take-off distance available may be more than 1000ft from that point. It was airborne before the end of the runway.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-03T15:26:55.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8903" PostTypeId="2" ParentId="8900" CreationDate="2014-10-03T15:53:45.393" Score="19" Body="&lt;p&gt;The standard operating procedures state that before &lt;strong&gt;every&lt;/strong&gt; flight, a thorough pre-flight inspection should be performed. Depending on the aircraft, minute and tiny details are not even omitted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things do not normally and occasionally fall off from a flying airplane, the same way as different objects do not fall from a driving car, although the pre-drive inspection of a car is no where nearly as comprehensive as the pre-flight inspection. Yet, how many times we have seen a bumper, guard, muffler or rear-view mirrors falling off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How dangerous it would be when it happens?&lt;/strong&gt; This depends on the part which has fallen. Some parts are not noticeable until landing or next inspection and some can cause disasters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.baltimoresun.com/&quot; rel=&quot;noreferrer&quot;&gt;Baltimore Sun&lt;/a&gt; reports &lt;a href=&quot;http://articles.baltimoresun.com/1995-11-24/news/1995328029_1_falling-debris-things-fall-older-aircraft&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No deaths or injuries have been reported in such incidents, but the&#xA;  Federal Aviation Administration is not even 100 percent certain of&#xA;  that.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The proper term for this incident is &lt;em&gt;Things Falling Off Aircraft&lt;/em&gt; (TFOA). The pilot must then submit a &lt;a href=&quot;http://navyaviation.tpub.com/14292/css/14292_77.htm&quot; rel=&quot;noreferrer&quot;&gt;hazardous material report&lt;/a&gt; within 24 hours in case the material can cause further harm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.askcaptainlim.com/-airplanes-aviation-39/153-do-aircraft-parts-often-fall-off-the-plane.html&quot; rel=&quot;noreferrer&quot;&gt;This site&lt;/a&gt; has listed some TFOA incidents:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;In August 2000, a KLM Royal Dutch Airlines Boeing 747 was forced to make an emergency landing when some engine pieces plummeted to the&#xA;  ground and landed on a crowded Los Angeles beach&lt;/li&gt;&#xA;  &lt;li&gt;On March 10, 2005, a couple taking a stroll through woodlands near Gatwick airport had a lucky escape when a door from a passing British&#xA;  Airways jet, crashed to earth. A part of the 70-pound door from a&#xA;  Boeing 777 had become dislodged just after take off and missed the&#xA;  couple by only 20 feet! &lt;/li&gt;&#xA;  &lt;li&gt;On August 11, 2006, a door fell off from a TAM Fokker 100 from Sao Paulo to Rio de Janeiro. It dropped off 18 minutes after departure but&#xA;  the plane was able to return to Sao Paulo without incident. Nobody was&#xA;  injured.&lt;/li&gt;&#xA;  &lt;li&gt;An engine exploded on a Japan Airlines flight bound for Tokyo with pieces of the engine falling on a neighborhood in Jakarta. The falling&#xA;  debris hurt no one but 16 homes were damaged.&lt;/li&gt;&#xA;  &lt;li&gt;The right wheel of a Blue Panorama Airlines Boeing 737 fell off after it departed from an airport in Spain and was forced to make an&#xA;  unscheduled landing amid emergency in Rome. &lt;/li&gt;&#xA;  &lt;li&gt;A similar incident happened near Los Angeles where an American Airlines Boeing 757 lost its right nose gear but managed to land&#xA;  safely with 105 passengers on board. &lt;/li&gt;&#xA;  &lt;li&gt;A landing gear door fell off a Delta Airlines Boeing 727 shortly after the plane took off from Boston*s Logan International Airport.&#xA;  The 30-pound metal door crashed into an empty street in a quiet&#xA;  residential neighborhood.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-10-29T18:29:04.833" LastActivityDate="2014-10-29T18:29:04.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8904" PostTypeId="1" AcceptedAnswerId="8910" CreationDate="2014-10-03T16:16:01.807" Score="11" ViewCount="17095" Body="&lt;p&gt;I suppose it may be different from an airline to another.&#xA;Given the maintenance, the time to load/unload the aircraft, the time the aircraft is grounded because there is no flight scheduled (e.g. at night), how many time an aircraft actually spend on ground compared to the time it spend in the air?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2019-02-06T00:34:53.017" LastActivityDate="2019-02-06T06:09:13.357" Title="What is the ratio between time in the air and time on ground for an aircraft?" Tags="&lt;airline-operations&gt;&lt;commercial-operations&gt;&lt;datasets&gt;&lt;economics&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8905" PostTypeId="2" ParentId="8825" CreationDate="2014-10-03T16:45:26.483" Score="16" Body="&lt;p&gt;It is called &quot;inboard aileron&quot; or &quot;high-speed aileron&quot; and is actually a flaperon. It will deflect with the flaps but not extend backwards. At high speed, the outboard ailerons are locked and all roll control is achieved by deflecting the inboard ailerons (and spoilers, if needed). This helps to reduce wing torsion and twist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Background: Since the trailing edge's sweep angle has a break at the wing station of the engine, and since in Boeing aircraft the flaps extend perpendicularly to the hinge line, there must be a gap between inboard and outboard flaps, otherwise they would collide during extension. This gap is best placed in the station of the engine blast, and is filled with a simple hinged flap. Note that Airbus aircraft have rear-sliding flaps, which stay at a constant span location and can be adjacent to each other even at the wing station of the sweep change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IFg9d.jpg&quot; alt=&quot;BAe Boeing 767 from below with flaps extended for take-off&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Boeing 767 from below. Picture by Adrian Pingstone (&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Ba_b767-300_g-bnwa_planform_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture is of a Boeing 767, but shows the flap arrangement nicely. Note the offset of the forward and rear part of the Küchemann bodies which house the flap tracks. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-12-22T18:58:35.083" LastActivityDate="2016-12-22T18:58:35.083" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8906" PostTypeId="2" ParentId="7757" CreationDate="2014-10-03T18:36:40.730" Score="1" Body="&lt;p&gt;According to this report, it is possible:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://yle.fi/uutiset/hs_finnair_pilots_report_dramatic_missile_near-miss_almost_30_years_on/7457577&quot; rel=&quot;nofollow&quot;&gt;http://yle.fi/uutiset/hs_finnair_pilots_report_dramatic_missile_near-miss_almost_30_years_on/7457577&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots of a DC10 flying from Japan to Helsinki in December 1987 claim to have seen a missile approaching while crossing the Arctic ocean, but it detonated 20 seconds before it would have hit, by their estimation. The incident was apparently covered up at the time.&lt;/p&gt;&#xA;" OwnerUserId="1981" LastActivityDate="2014-10-03T18:36:40.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8907" PostTypeId="1" AcceptedAnswerId="8909" CreationDate="2014-10-03T18:38:27.440" Score="21" ViewCount="13188" Body="&lt;p&gt;While doing an image search, I found these images of propellers:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Lmrr9.jpg&quot; alt=&quot;prop1&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4MVWB.jpg&quot; alt=&quot;prop2&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some appear to be straight-ish on the leading edge and curved on the trailing, some curved on the leading edge and straght-ish on the trailing, and symmetrically curved and some pretty squared off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like, well, a propeller is a propeller. They all need to push the air back in a way as to propel (hence the name?) the plane forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't there be a mathmatically 'best' design?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2015-02-23T12:54:58.897" LastActivityDate="2019-07-08T14:04:37.353" Title="Why are there so many different propeller shapes?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8908" PostTypeId="2" ParentId="8899" CreationDate="2014-10-03T19:20:44.327" Score="8" Body="&lt;p&gt;Without having a better understanding of the actual crosswind there's no way to say whether that one was out of limits. If I had to guess I'd say it was close. I fly light aircraft, not commercial jets but as far as I know takeoff in a heavy crosswind is similar - you keep aileron into the wind, and a bit of forward pressure on the stick to make sure your wheels have good contact to the ground. During the roll you build up a bit of extra speed so when you are ready to rotate you get well off the ground quickly so you get some ground clearance, and also have better control authority. It looks to me that's what these pilots did. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the conditions it was never going to be a comfortable ride, I see nothing wrong with the take-off. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-03T19:20:44.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8909" PostTypeId="2" ParentId="8907" CreationDate="2014-10-03T19:26:43.570" Score="26" Body="&lt;p&gt;The best design depends on what your goal is. This changes with operating conditions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Best power/thrust ratio&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For lightly loaded propellers this would be minimum induced loss. These are the propellers on human-powered aircraft, windmills or motor gliders. Minimum induced loss is achieved by distributing circulation elliptically across the propeller disc, and a typical consequence is a small chord near the tips and a low number of propeller blades. If you want to research this more, I recommend to play around with &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xrotor/&quot; rel=&quot;noreferrer&quot;&gt;XRotor by Mark Drela&lt;/a&gt; (and maybe reading &lt;a href=&quot;http://www.mh-aerotools.de/company/paper_1/epplerhepperle.pdf&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;). Mark used it to design the &lt;a href=&quot;http://en.wikipedia.org/wiki/MIT_Daedalus&quot; rel=&quot;noreferrer&quot;&gt;MLE (below, NASA photo EC87-0014-8) and Dedalus&lt;/a&gt; propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IzxXx.jpg&quot; alt=&quot;MIT MLE in flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Maximum thrust at high speed&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Highly loaded propellers, which can be found on large turboprop aircraft, are less concerned with induced loss, but need to put out as much thrust as possible with a limited prop area. The diameter is restricted to limit tip speeds, and the tips typically are mildly supersonic. To limit the suction peaks on the blades, the local lift coefficient needs to be low, which is achieved by increasing chord and the number of blades. Increasingly, now tip sweep is also used, but this drives up the torsional loads on the blades and leads to warpage in operation. An extreme example is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Progress_D-27&quot; rel=&quot;noreferrer&quot;&gt;P-27 prop on the D-27 turboshaft of the An-70 transport&lt;/a&gt; (below, picture by Marina Lystseva).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/diYqW.jpg&quot; alt=&quot;An-70 with P-27 propeller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Ship propellers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They operate in a medium which is 800 times denser than air, and the main concern is to avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Cavitation&quot; rel=&quot;noreferrer&quot;&gt;cavitation&lt;/a&gt;. This again means to limit suction peaks and leads to very high blade chords. To limit draft, ship propellers need to have extremely small diameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/huxDy.jpg&quot; alt=&quot;Five-bladed ship propeller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Submarine propellers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For submarines, add  minimum noise emission to the design goals. Minimum draft is not a concern, so the propeller blades are less stubby. Their sweep distributes the cutting through the wake of the rudders over time, which helps a lot to reduce noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vDXwO.jpg&quot; alt=&quot;Submarine propeller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fancy shapes of some model aircraft propellers have more to do with marketing or unscientific voodoo beliefs by some hobbyists. Generally, a straight shape works best.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-28T07:57:59.520" LastActivityDate="2016-01-28T07:57:59.520" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8910" PostTypeId="2" ParentId="8904" CreationDate="2014-10-03T19:57:34.183" Score="15" Body="&lt;p&gt;It will vary widely from aircraft to aircraft, but I will try to give some general estimates.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Time on the Ground&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Part of what you are referring to what is sometimes called &lt;em&gt;&lt;a href=&quot;https://www.google.com/search?client=ubuntu&amp;amp;channel=fs&amp;amp;q=aircraft%20turn%20time&amp;amp;ie=utf-8&amp;amp;oe=utf-8&quot; rel=&quot;noreferrer&quot;&gt;aircraft turn time&lt;/a&gt;&lt;/em&gt;. It's not really directly related to my calculations for your overall question (though it is certainly a factor for short-haul jets), but in &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_01/textonly/t01txt.html&quot; rel=&quot;noreferrer&quot;&gt;this article&lt;/a&gt;, minimum turn times for the Boeing 757 was studied, and it was found that the estimated turn time for a 757-200 was 52.5 minutes, based on actual operations. The 757-300, a stretched model with more seating, would take about 59 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=8&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CFoQFjAH&amp;amp;url=http%3A%2F%2Fwww.agifors.org%2Fdocument.go%3FdocumentId%3D1666%26action%3Ddownload&amp;amp;ei=AQAvVISzKYiwyATthIG4DA&amp;amp;usg=AFQjCNGfuKQ43AFcwiYhX_xon6UVH1JfOg&amp;amp;sig2=SY_cLF-qhNFQkgdiWKdFhw&amp;amp;bvm=bv.76802529,d.aWw&quot; rel=&quot;noreferrer&quot;&gt;this presentation&lt;/a&gt;, presented by United Airlines, they show a general guideline MSGT (Minimum Scheduled Ground Time), that is a generalization depending on flight locations, field facilities, and airlines. Some times are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 747: 80 minutes&lt;/li&gt;&#xA;&lt;li&gt;Boeing 777: 70 minutes&lt;/li&gt;&#xA;&lt;li&gt;Boeing 767: 60 minutes (-300 model)&lt;/li&gt;&#xA;&lt;li&gt;Boeing 737: 35 minutes (-300 model)&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320: 40 minutes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/1567507/&quot; rel=&quot;noreferrer&quot;&gt;This link&lt;/a&gt; has a discussion of a number of airliner turn times, however none are from official sources. Most vary between 20-45 minutes, depending on if cleaning is required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So for a typical airliner we can say it takes about 45 minutes-1 hour for a typical servicing.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aircraft Lifetime&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Now as to how many times they fly, you can find their aircraft design cycle limit (essentially, how many takeoffs and landings it can make in its lifetime) in &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/FR-2010-11-15/html/2010-28363.htm&quot; rel=&quot;noreferrer&quot;&gt;this Federal Register document&lt;/a&gt; (summarized &lt;a href=&quot;http://www.airwaysim.com/forum/index.php?topic=30738.0&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;). Some listed numbers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 747: 20,000 cycles&lt;/li&gt;&#xA;&lt;li&gt;Boeing 777: 40,000 cycles&lt;/li&gt;&#xA;&lt;li&gt;Boeing 767: 50,000 cycles&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320: 48,000 cycles (60,000 hours)&lt;/li&gt;&#xA;&lt;li&gt;Airbus A300: 40,000 cycles&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So for a 'typical' airliner we can say it can survive about 40,000 cycles in a lifetime&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find the average age of airliners in different places online. &lt;a href=&quot;http://www.airsafe.com/events/airlines/fleetage.htm&quot; rel=&quot;noreferrer&quot;&gt;This site&lt;/a&gt; splits up by airline and aircraft, and most airliners have an average age of 12-15 years. But note that this is the &lt;em&gt;active fleet&lt;/em&gt;. &lt;strong&gt;The average age at retirement for an airliner is now &lt;a href=&quot;http://aviationweek.com/awin/aircraft-retirement-age-drops-again&quot; rel=&quot;noreferrer&quot;&gt;around 24-25 years&lt;/a&gt;.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;You can find a related Aviation.SE question &lt;a href=&quot;https://aviation.stackexchange.com/questions/2263/what-is-the-lifespan-of-commercial-airframes-in-general&quot;&gt;here&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aircraft Usage&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/492074/&quot; rel=&quot;noreferrer&quot;&gt;This thread&lt;/a&gt; discusses the average cycles and flight hours per day. Long haul aircraft (like the 747, 777, A380) tend to spend more hours in the air per flight, but also have less cycles per day. I can't find official sources, but the thread presents a couple example averages for peak usage rate:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Delta Boeing 757: 9.5 hours/4.8 cycles&lt;/li&gt;&#xA;&lt;li&gt;United Boeing 747: 13.2 hours/1.6 cycles&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(I find these probably accurate, as there have been some publicized accidents that have much higher usage, like &lt;a href=&quot;http://latimesblogs.latimes.com/lanow/2011/04/faa-southwest-plane-torn-fuselage-average-7-flights-a-day.html&quot; rel=&quot;noreferrer&quot;&gt;this one&lt;/a&gt;, which flew 48,740 hours and 39,781 cycles in 15 years - about 7 flights/day; short-haul jets like the one in the article end up with more cycles than long-haul, as I noted above).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is difficult to find hard numbers, but overall, &lt;strong&gt;the average flight length for a short-haul jet is about 2 hours, whereas a long-haul jetliner is around 6-7 hours.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, there are a lot of variables in this question, but using the above data, we can estimate the answer to your question, using these estimated figures from above:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;40,000 cycles (~20,000 flights)&lt;/li&gt;&#xA;&lt;li&gt;25 years&lt;/li&gt;&#xA;&lt;li&gt;2 hours/flight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This means approximately 40,000 flight hours for a typical short-haul jet; over 25 years (219,000 hours), this works out to about 1 hour in flight for every 5 on the ground. Obviously this varies widely, but for a ballpark number, that's the best I can do. The highest usage would be a heavily used long-haul jet used on the longest routes from a busy airline (i.e. trans-Pacific; Middle East to U.S.), whereas the lowest would be a moderate-length flight on a low-volume route. &lt;strong&gt;In general, you are probably looking at about 1:3 to 1:5 air:ground time&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-10-04T15:48:33.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8911" PostTypeId="2" ParentId="8899" CreationDate="2014-10-03T20:38:36.057" Score="4" Body="&lt;p&gt;Assuming everything was within its limits since we can't prove otherwise and therefore a legitimate take-off, it's the captain's call whether to take-off or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, judging by the video, the precipitation seems far too severe to consider this take-off completely safe. Also, the crosswind might have been quite strong considering the open spoilers (also called airbrakes) caused by full left aileron being applied to compensate for the crosswind, which ultimately increases the take-off distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, if it was a stormy &lt;a href=&quot;http://en.wikipedia.org/wiki/Cumulonimbus_cloud#Effects&quot; rel=&quot;nofollow&quot;&gt;cumulonimbus cloud&lt;/a&gt;, the take-off could have been delayed by half an hour, and the meteorologic conditions would have been much better in terms of precipitation (and it would avoid scaring all the passengers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my point of view the main problem with such take-off would be in case of a take-off emergency (like an engine flame out due to the intensive water ingestion) before &lt;a href=&quot;http://en.wikipedia.org/wiki/V_speeds#V1_definitions&quot; rel=&quot;nofollow&quot;&gt;V1&lt;/a&gt;, forcing the pilots to brake, risking a runway overrun due to hydroplaning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They made it, but I don't think it was the smartest decision!&lt;/p&gt;&#xA;" OwnerUserId="854" LastEditorDisplayName="user3338" LastEditDate="2014-10-04T08:36:17.677" LastActivityDate="2014-10-04T08:36:17.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8912" PostTypeId="2" ParentId="8899" CreationDate="2014-10-04T00:55:58.883" Score="0" Body="&lt;p&gt;It looks like it was raining (a lot) with a pretty good crosswind. They probably loaded extra fuel for the weather and decided to rotate &lt;em&gt;after&lt;/em&gt; Vr instead of exactly at Vr, thus using more runway. Wiggling the controls around didn't help the takeoff roll but it did keep the plane straight - usually a good thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a passenger this would not have bothered me at all. Some years ago I was departing Hong Kong on Northwest, right in the middle of a typhoon. We sat at the threshold for 20-30 minutes, then the engines went to full power and we got out of there. The FA across from me said the flight crew told them to buckle in and stay seated for 20 minutes after takeoff, and she'd never heard that in her career. So obviously the pilot felt it was going to be a rough ride but he also felt it would not be a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing back at the airport in the video would have been quite exciting, possibly requiring the Force in addition to redundant Cat IIIb autoland. But there's no requirement that you return to your departure airport if you have a problem - if there's another one 10 minutes away with better weather you go there instead.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-10-04T13:19:16.943" LastActivityDate="2014-10-04T13:19:16.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8913" PostTypeId="1" CreationDate="2014-10-04T01:26:27.123" Score="23" ViewCount="13036" Body="&lt;p&gt;Im looking at purchasing  disused 747-400:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft will be stripped of all seats and other non essential items.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft will be then flown to my property in Victoria, Australia and perform a one off landing.&lt;/li&gt;&#xA;&lt;li&gt;The landing distance would be between 1500-2300 feet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Can this be done?&lt;/p&gt;&#xA;" OwnerUserId="3743" LastEditorUserId="2176" LastEditDate="2015-06-12T16:57:37.363" LastActivityDate="2016-03-18T07:46:03.320" Title="What is the minimum stopping distance for a 747-400?" Tags="&lt;aircraft-performance&gt;&lt;boeing-747&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8914" PostTypeId="1" AcceptedAnswerId="8923" CreationDate="2014-10-04T01:53:37.877" Score="21" ViewCount="10697" Body="&lt;p&gt;While doing an image search, I found many different shaped propellers and asked about them in &lt;a href=&quot;https://aviation.stackexchange.com/questions/8907/propeller-shapes&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In it, Peter Kampf answered my question with his usual thoroughness. However, as I looked at more images of various shaped blades, I saw images of the helicopters of my youth, Bells. The Bell Huey and the Cobra both have very long, very squared off primary blades. They don't have an aerodynamic looking shape and both the leading and trailing edges are straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would Bell have chosen this shape and not the shape more like a 'normal' plane propeller?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2018-05-23T19:38:20.547" Title="Why don't helicopter blades look like other propellers?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8915" PostTypeId="2" ParentId="8900" CreationDate="2014-10-04T02:48:23.607" Score="10" Body="&lt;h2&gt;Answer - Very dangerous!&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I have 1st and 2nd hand information, so I can speak reliably on this issue. In 2005, a NW DC-10 from MSP to HNL noticed abnormal heat (TIT) on #2 Engine on their final approach. The Operations Dept., where I worked at the time, told them that the thrust reverser for #2 had fallen off on the initial climb (approximately 8,000 ft.), and landed in a field adjacent to a public golf course, next to where a lead mechanic lived and he reported it to OP's, as the plane was making their final approach in HNL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Independently, my 2 sisters were playing a round of golf at that golf course at the time, when one of them looked up in the air, pointing at a large object rapidly falling and said, &quot;What's that?&quot; Later, the following day, I got a good look at 6-7' round, composite metal object weighing about 300-400lbs with a lot of grass embedded into it (how does grass get embedded in the #2 thrust reverser-the engine mounted right below the rudder?) sitting on a pallet on the hangar floor. Needless to say, an object that size and weight falling from that height could REALLY do some serious damage.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;But why did it happen?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;DC-10's are mostly retired from service now, giving way to much more fuel-efficient airplanes, but it was not common practice to use the #2 thrust reverser, so when 'A' or 'B' checks came around, it was commonly not looked at, as there was 'theoretically' no reason to do so. The card did come up on &quot;C&quot; checks, but the now-deceased NWA had a policy of 'farming out' &quot;C&quot; checks overseas, in which case it was someone in MSP 'verifying' work was done in Honduras, Singapore, China, and elsewhere. Ignore something long enough, especially on a heavy commercial aircraft with lots of vibration and you will reap the consequences! The company immediately inspected all other DC-10's in it's fleet and found several others approaching the shear point that the original one did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew was unaware it had detached in flight; it presented no compromise in the airworthiness(in a normal situation), and it wasn't until it's final approach some 8 1/2 hrs later that they noticed something peculiar, which was verified by OP's. But it could have been a catastrophe on the ground, and it speaks to the fact that there are no shortcuts to safety, no matter how cheap the ticket prices are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further information can be found &lt;a href=&quot;http://www.wings900.com/vb/1-1-civil-aviation/19744-nw-dc-10-loses-thrust-reverser-during-flight.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.  &lt;/p&gt;&#xA;" OwnerUserId="3671" LastEditorUserId="3671" LastEditDate="2017-06-21T22:51:55.327" LastActivityDate="2017-06-21T22:51:55.327" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8916" PostTypeId="2" ParentId="8913" CreationDate="2014-10-04T02:55:00.797" Score="8" Body="&lt;p&gt;You can find detailed technical specifications  for the 747-400 in &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this document&lt;/a&gt;. On page 97, a landing chart appears:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DIDLz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Operating_empty_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;operating empty weight&lt;/a&gt; (OEW) of a 747-400 (from the same document) is 394,088 lbs (178,756 kg). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though the chart does not go all the way down to 394,088 pounds, towards the lower end of the chart, the change is almost linear, so we can get a rough estimate of the landing runway length requirement at OEW. With Flaps 30, at Sea Level, on a Dry Runway, you're looking at about a 1,390 &lt;em&gt;meter&lt;/em&gt; requirement (about 4,560 feet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approximate slope of the graph is for every 100,000 pounds lost, landing distance decreases by 300 meters (~984 feet). Obviously this is not &lt;em&gt;completely&lt;/em&gt; accurate, but for this purpose, it'll do. To land on a 2300-foot runway, you would need to lose another 230,000 pounds or so, putting the weight around 165,000 pounds. I'm fairly sure that stripping all nonessential equipment would not be enough here, and this ballpark estimate would require you to touch down brick one, with no gas, and no extra runway. Even if you could fly a 165,000 747, I wouldn't try to land it on that short of a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in answer to your question: &lt;strong&gt;No, I'm certain this cannot be done&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-10-04T03:07:43.287" LastActivityDate="2014-10-04T03:07:43.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8917" PostTypeId="1" CreationDate="2014-10-04T03:16:32.200" Score="34" ViewCount="87958" Body="&lt;p&gt;I have pretty bad flying phobia and often wonder what would happen if all the engines on the craft went out at the same time. I initially had the anxiety-ridden thought that the hundreds of thousands of pounds of metal would nose-dive and explode into the Earth. Then I read somewhere that the plane would actually glide forward as it descended, making a landing where all passengers survive a possibility. What if you were flying over the ocean versus flat land versus mountains? Has complete engine failure ever happened?&lt;/p&gt;&#xA;" OwnerUserId="3745" LastActivityDate="2017-06-18T11:04:10.843" Title="If a typical passenger plane had total failure of all engines mid-flight, is it possible for passengers to survive?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;airliner&gt;&lt;emergency&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8918" PostTypeId="2" ParentId="8913" CreationDate="2014-10-04T03:55:52.740" Score="28" Body="&lt;p&gt;Interesting question. I think it could be done in the right conditions if you are willing to accept some damage and depending on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the runway level or uphill/downhill? If you could land uphill in a high wind that was almost all headwind, I believe you could either do it or would overrun the runway at a low speed. Airplanes slow down really quickly going uphill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A stripped 747-400 probably weighs about the same as a 747-400 freighter, maybe a little less because the freighter has the equipment for loading and securing pallets. If you're using Firefox or Chrome (IE won't work), click on any aircraft at &lt;a href=&quot;http://747.terryliittschwager.com&quot;&gt;747.terryliittschwager.com&lt;/a&gt; and you'll see the empty weight is around 362,000 lbs (you can change the weight unit to kilos there if you wish).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used to land at Tel Aviv with only 15,000 lbs of fuel in 747-200s. The -400 burn rate may be a little higher, but let's use that. You would have to be comfortable with being totally committed to landing, with the possibility of only one quick go-around. Maybe you could even cut the 15,000 down to 10,000 with no go-around possibility?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's use 375,000. Vref for a -200 at 400,000 (lowest figure in the table I have) is 118 kts. In that area Vref decreases 3 kts for every 20,000 drop in weight, so we can take that 118 down to 115. I forget whether Vref is 1.2 or 1.3 times stall. Let's use 1.2, which would put the stall at 96. I would imagine a -400 is comparable insofar as these speeds are concerned, but I don't know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about one-time-use arresting gear of some sort on the last 400 meters of runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could drop some more weight by taking out one engine. 747s regularly do 3-engine ferries. It's no big deal. However, I'm not sure if the weight loss would be worth losing the reverse thrust of the engine being taken out. There is a lateral imbalance consideration there, but 747s used to carry a spare engine in a pylon under the wing, so if you removed an inboard engine, I'm guessing you could live with the imbalance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking of reverse thrust, it used to be for the 747-200 that the published figures for minimum landing distance were brakes only, no use of reverse thrust. If that's the case for the chart shown in the previous answer, the figures there can be reduced, and you would want to use FULL reverse immediately. Don't worry about compressor stalls, after all, I'm guessing you're not going to use the engines again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I'm sure there are performance figures for the effect of runway slope and headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be a challenging situation, one of those things some crazy Aussie might try!  lol&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-10-04T19:22:26.243" LastActivityDate="2014-10-04T19:22:26.243" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="8919" PostTypeId="2" ParentId="8917" CreationDate="2014-10-04T03:59:17.220" Score="61" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Transat_Flight_236&quot;&gt;Air Transat Flight 236&lt;/a&gt; experienced a complete power loss over the Atlantic Ocean in 2001. Yes, all passengers and crew survived after the aircraft glided 75 miles to a runway on the Azores islands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in the event of the loss of all engines, an aircraft can keep its critical electrical systems running thanks to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot;&gt;ram air turbine&lt;/a&gt; which allows the crew to maintain control of the aircraft and to communicate with ground crews to determine the best course of action for the situation. This was the case with Air Transat Flight 236.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, consider &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;US Airways Flight 1549&lt;/a&gt; which experienced a complete power loss after takeoff due to a double bird strike. Even in the situation where the pilot had very few options due to being at such a low altitude and being over a populated area, all passengers and crew survived after ditching in the Hudson River. However, in all fairness, ditching attempts do not normally end well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all, complete power loss in a modern airliner is extraordinarily rare. While gathering links for this answer, I ran across the &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airline_flights_that_required_gliding&quot;&gt;List of airline flights that required gliding&lt;/a&gt;&quot; article on Wikipedia. The short length of the list speaks for itself (4 flights in the last decade).&lt;/p&gt;&#xA;" OwnerUserId="2183" LastEditorUserId="2183" LastEditDate="2014-10-05T20:55:39.670" LastActivityDate="2014-10-05T20:55:39.670" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8921" PostTypeId="2" ParentId="8913" CreationDate="2014-10-04T06:34:15.080" Score="22" Body="&lt;p&gt;No, it can't be done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has been a similar situation in the Netherlands. KLM donated an old B747-200SUD to the Aviodrome Aviation Themepark at Lelystad airport. Lelystad airport is a general aviation field located about 60 kilometers from Amsterdam airport and has a 4100 feet runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a stripped down B 747 would require more runway. In addition, the weight would damage the runway and taxiways at the destination since these are designed for a lighter category of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They ended up taking the plane apart and shipping it over the canals and a lake to its final home.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/kscUS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/B4w7b.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z79Sx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-04T06:34:15.080" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8922" PostTypeId="2" ParentId="1464" CreationDate="2014-10-04T08:00:45.410" Score="8" Body="&lt;p&gt;People have assumed that you are referring to US operations. But in the UK and Australia (and possibly many more countries), ATC can not give 'conditional' landing clearances. Clearance to land in these countries is not given until the runway is clear. The US ATC can give &quot;cleared to land number 2 behind the 737 on final&quot; but you won't hear that where I live (down under). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, unlike in the USA, the UK and Australia (and again, possibly others), ATC may give a clearance of &quot;Behind the inbound 737 line up and wait, behind&quot;. You can make safety arguments against either of these procedures, it's just a quirk of the international system that there are different philosophies in different places. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-04T08:00:45.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8923" PostTypeId="2" ParentId="8914" CreationDate="2014-10-04T08:13:05.857" Score="28" Body="&lt;p&gt;Helicopter blades need to be long and thin. The diameter of the rotor disc determines the efficiency of the rotor at low speeds and can be compared to the wing span in fixed-wing airplanes. The rotation creates strong centrifugal loads at the blade roots which grow with the square of the tip radius at a given rotation speed, so they cannot be tapered much. Adding chord to the middle of the blade would increase its area and add more friction drag, increasing the torque needed to keep the rotor spinning. If the helicopter is only designed for hover, the blade tips could be tapered, but the added complications of forward flight make a rectangular blade the better choice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In forward flight, the speeds due to the blade's rotation and the flight speed add up, increasing local airspeed at the advancing blade and reducing it at the receding blade. Since the center of lift is trimmed to be at the rotor hub using the &lt;a href=&quot;http://en.wikipedia.org/wiki/Swashplate_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;swash plate&lt;/a&gt;, the advancing blade has a smaller angle of attack and the receding blade a higher angle of attack. On the receding blade at high flight speed, the root will be in reverse flow since here the rotation speed will not be high enough to compensate for the flight speed. Dynamic pressure is around zero at the middle radius, and only the tip area sees sufficient dynamic pressure to create the lift which is demanded from the blade. Reducing this tip area would reduce the lift which can be produced there, so designers kept the blade chord constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two effects limit the maximum forward speed: The remaining dynamic pressure at the blade tip of the receding blade, and the maximum Mach number at the advancing blade's tip. In order to increase this maximum Mach number, modern rotor tips are swept, but simple sweep will lead to torsion moments which will twist the blade. The pitching moment along the blade needs to be finely balanced so no torsion loads result. To achieve this, helicopter blade airfoils are either symmetric or reflex, and the tip is first swept forward and then backward, so the resulting lift acts exactly at the &lt;a href=&quot;http://encyclopedia2.thefreedictionary.com/elastic+axis&quot; rel=&quot;nofollow noreferrer&quot;&gt;elastic axis&lt;/a&gt; of the blade. See the picture of such a blade tip below. The small trim tab you can see at the trailing edge is used for fine-tuning the pitching moment of the blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BPmHY.jpg&quot; alt=&quot;Eurocopter Blue Edge rotor blade&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eurocopter Blue Edge rotor blade (picture &lt;a href=&quot;https://www.wired.com/2010/02/eurocopter-moves-one-step-closer-to-whisper-mode/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would not be surprised if an optimized rotor shape has non-rectangular blades, but my impression is that the gains of optimization are small, especially with the wide spread of operation conditions of all rotor blade sections. The rectangular blade is easy to manufacture and good enough for most cases. However, I have not designed a rotor myself and do not know enough about the details to be more specific.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-05-23T19:38:20.547" LastActivityDate="2018-05-23T19:38:20.547" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="8924" PostTypeId="2" ParentId="82" CreationDate="2014-10-04T08:20:03.393" Score="8" Body="&lt;p&gt;True North is the North Pole. The maps used for navigating are oriented to the North Pole. A pilot can measure the direction between two points to create a 'track' or 'course' to fly in degrees true. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Magnetic North is where the compass points - which is not actually the North Pole. Magnetic North is currently over northern Canada. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angular difference between True and Magnetic north is called Magnetic Variation. This number varies depending on where you are on the earth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Magnetic Variation is the bugbear of many student pilots. Why is it important? Well if your track to fly (ascertained from a map) is 360 degrees true in relation to the North Pole, you should be flying right to the North Pole. But 360 degrees on the compass points to Magnetic North in Canada. If you haven't applied magnetic variation, you could be flying as much as 15 degrees or so off course. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runway names are the headings given in degrees magnetic, but as magnetic north is slowly moving, occasionally the runway name (eg 35/17) will change. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-04T08:20:03.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8925" PostTypeId="2" ParentId="5121" CreationDate="2014-10-04T08:44:04.377" Score="5" Body="&lt;p&gt;Gonna try give as simple an answer as possible, but speeds in aviation takes a bit to get your head around....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpit airspeed indicator (ASI) measures &lt;em&gt;indicated airspeed&lt;/em&gt;, or IAS, measured in knots. But IAS is technically not a speed at all. It can be thought of as a measurement of the pressure of the air molecules flowing over the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;IAS is the most important speed because if the pressure of air molecules going over the wing is too low you'll lose lift and stall. More speed though means more pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high altitude, there are less air molecules, so less pressure on the wing. Therefore, to keep the same pressure on the wing (i.e to keep the same IAS), you need to go faster. &lt;em&gt;True airspeed&lt;/em&gt; (TAS) measures how fast you are actually going. In flight it will be higher than the IAS. TAS does not care about the pressure over the wing - it's the speed through the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Groundspeed&lt;/em&gt; (GS) is simply the TAS with the effect of wind added. Groundspeed is the speed of aircraft in relation to the ground. If you have a TAS of 200kts, and a tailwind of 50kts your speed over the ground will be 250kts. This is the speed the GPS will show. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-04T08:44:04.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8926" PostTypeId="2" ParentId="8891" CreationDate="2014-10-04T09:31:24.200" Score="9" Body="&lt;p&gt;I am Australian and I hope I can help. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, you don't need to fly through a university. There are hundreds of private flight schools here which are of great quality, and very few of them are associated with a university. More and more international airlines are sending cadet pilots to our schools. Most of them offer theory courses in addition to the flying, or you can always self study. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, the university courses are great and airlines like people with a degree (but it's not mandatory to have one). You'll be paying more though, it's a trade-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your comment about small planes - All flying is initially in light aircraft - even if you got an airline cadetship you start small. No single course in Australia or anywhere will let your first flight be in a jet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking of airline cadetships - these are definitely the best and quickest way to get into an airline cockpit but the positions are highly competitive (and maybe not open to international students, I don't know). But you can still get an airline job without a cadetship...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The normal progression is this - you can technically get a flying job after 150-200 hours of private training and flying, having achieved your commercial pilot licence (CPL). I say 'technically' because if you only have minimum hours and minimum qualifications you have to look very hard for a job. Most people straight away get an instructor rating, so they can get a job teaching people to fly. Other early jobs include sightseeing flights, parachute flights, and mail flights to remote towns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your training will have been in light aircraft, but fortunately Australia has possibly the largest light aircraft industry in the world, so there's lots of jobs in these planes. It's highly unlikely that your first job will be in anything bigger than a 6 seater plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get extra qualifications (such as multi-engine endorsement, and instrument rating), you can get more jobs, and gradually fly bigger aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After you have your CPL, the next big step is the Air Transport Pilot Licence (ATPL). Regional airlines here generally require as a minimum, 1000 flying hours in light aircraft, the multi engine rating, the instrument rating, and passes in the ATPL theory exams - note that you don't necessarily need the ATPL licence itself. It will take most people a couple of years until they get this experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have that much experience flying 6 to 8 seat aircraft, it's not actually a huge leap to the 20 seat planes of the regional airlines, and the airlines will train you for this step. And once you've flown those for long enough any airline can train you to their jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course if you want to go back home after the training it will be different. But no school here can train anyone to go straight to an airline. You've got to do the small things first. Think of it as character building!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sorry but I'm a bit rushed for time but I hope I've helped a bit. Australia is one of the best places in the world to train in my opinion (but I might be biased!). Please ask if you have any more questions. And good luck. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-04T09:31:24.200" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8927" PostTypeId="2" ParentId="8917" CreationDate="2014-10-04T09:48:22.613" Score="4" Body="&lt;p&gt;Yep, planes can glide an very long distance, depending on the starting height and atmospheric conditions. All pilots are trained on how to glide as far as possible. In addition it is also EXTREMELY rare for all engines to fail, and modern passenger jets can fly safely even if one engine fails.&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3789" LastEditDate="2014-10-06T03:33:09.990" LastActivityDate="2014-10-06T03:33:09.990" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8928" PostTypeId="2" ParentId="8913" CreationDate="2014-10-04T14:05:44.620" Score="10" Body="&lt;p&gt;The charts say no, and I agree. 3000 feet is standard at a small GA airport and that's tight even for a Gulfstream. If your runway is that short have you considered the width? A 747 has 11 meters between the tires - although you might stop a lot faster with the outboard wheels in the grass it will be really difficult to move it after it stops. Only one wheel in the grass could be quite exciting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without running the numbers ('cause your case is well off the charts) in self-contradiction I will say that it's conceivable that if you land with NO fuel remaining, full flaps, set the mains down right on the beginning of the pavement, apply full reverse and full braking, AND do this on a day with a cooking headwind you &lt;em&gt;might&lt;/em&gt; pull it off. Heavy rain will actually help here as a few inches of standing water on the runway will slow you down pretty fast. Of course, you have no option for a go-around. Such a landing would be illegal in almost any developed country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who's going to fly it? 747 drivers are used to things like 12,000 foot paved surfaces and ILS, not bush-grade airstrips in the outback. Bush pilots who think 1500 feet of pavement is a luxury typically don't know how to fly a 747. Just in case you don't know, large aircraft licenses are NOT interchangeable. You need a commercial license, ATP and a type rating. For an older 747 it's a fairly small club.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do go ahead with the project, call the Discovery Channel, producers of Dangerous Flights. they'll probably be interested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oh, and forget the parachute. I'm a master parachute rigger - anything capable of slowing a 747 will take 1500 feet just to deploy (you have to stage it). And the plane is not equipped with the necessary attachments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe a dozen JATO bottles hooked up backwards?&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-04T14:05:44.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8929" PostTypeId="2" ParentId="8917" CreationDate="2014-10-04T16:39:49.123" Score="26" Body="&lt;p&gt;The fundamental parameters that determine how survivable a plane crash is include the &lt;em&gt;vertical air speed&lt;/em&gt; (relative to the ground); &lt;em&gt;where&lt;/em&gt; the plane strikes (ideally, it touches down on its landing gear or, in the worst case, on its belly, scraping against the ground); and how long it takes for rescuers to locate the downed plane and provide assistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To keep your vertical air speed at a low enough level that there's a chance for people to survive, you must have &lt;em&gt;flight control surfaces&lt;/em&gt; working. That means the wings, the vertical stabilizer or tailplane, and ideally, the ailerons and flaps. These systems do one of two things (some of them do both): they either generate &lt;em&gt;lift&lt;/em&gt; (the wings do most of this), or they provide &lt;em&gt;attitude control&lt;/em&gt; (roll, pitch, and yaw).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, while the engines are not critical to provide attitude control and they are not required to generate lift, the airplane will steadily lose altitude without the engines generating &lt;em&gt;thrust&lt;/em&gt;. An airplane is nominally &lt;em&gt;controllable&lt;/em&gt; if the attitude controls are working, and the major providers of lift are doing their job (by not, for example, being torn off by an engine explosion). An airplane that is not controllable is almost always doomed to lose all souls aboard. However, an airplane that &lt;em&gt;is&lt;/em&gt; controllable but has no engines can, in many cases, land safely, or with a majority of the lives on board being saved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Survivability mostly depends on the following factors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the engines fail, &lt;em&gt;why&lt;/em&gt; did they fail? If they failed because fuel is exploding in the fuel tanks or starting a fire that could damage the flight control surfaces or hydraulic lines, then things are looking pretty grim. If they just have some minor mechanical problem that causes the engine to semi-gracefully stop spinning, or they ran out of fuel, or the engines &quot;implode&quot;, that's less dire. Modern turbofan engines have to be tested and proven that they would vent all their debris out the back of the engine instead of flying around horizontally, so that shards of metal with very high velocity don't cut into the plane's fuselage or wings, which could cause catastrophic damage.&lt;/li&gt;&#xA;&lt;li&gt;When the engines fail, what happens to the debris they make, if any? Similar to the first bullet, but &lt;em&gt;if&lt;/em&gt; shards of high-speed metal were to strike the fuselage, wings or tail, it could make the airplane uncontrollable.&lt;/li&gt;&#xA;&lt;li&gt;How high was the plane when the engines failed? The more altitude you have, the better.&lt;/li&gt;&#xA;&lt;li&gt;How fast was the plane's airspeed when the engines failed? The more airspeed you have, the better. Both airspeed and altitude increase the range that the plane can glide before it collides with the ground, which means the pilots have more time to figure out where to land, come up with an approach, and execute the approach.&lt;/li&gt;&#xA;&lt;li&gt;Are the landing gear able to come down on their own by gravity alone? This is always a risk: if you try landing on the fuselage, things will not go very well, especially because the unavailability of the engines means you have one less way to slow down the airplane once you touch the ground (no reverse thrust). If the landing gear deploys successfully, that certainly works in the pilot's favor.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In terms of the locations where you would ideally &quot;want&quot; to lose all your engines (and by &quot;want&quot; I mean in terms of the greatest likelihood of survivability), I'd rank them as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;High in the sky, above a populated area. The good news is, populated areas have lots of airports. Airports are the best places to land a plane, because they have emergency crews on the scene and the runway is ideally suited to giving your plane the room it needs so it doesn't collide into anything. The bad news is, if your engines explode and make debris, it falls on people below you. Oh well -- you can't have everything you want in an emergency situation.&lt;/li&gt;&#xA;&lt;li&gt;Above a small body of water, near a populated area. Hey, it worked well for Sully. Boats were in the area, so they came out to rescue the passengers.&lt;/li&gt;&#xA;&lt;li&gt;Out in the desert. The B727 test crash on Discovery channel suggested that quite a few people would be surviving that crash. They crashed her on flat ground out in the desert. You'd be hard-pressed to get help any time soon if you were isolated from civilization, but at least the landing gear could do some work to help prevent a catastrophic explosion or fire.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Everywhere else.&lt;/strong&gt; Landing in hilly or mountainous terrain, very cold places, very wet places far from other people, inside an active volcano, etc. is pretty bad. I don't recommend it. If the plane isn't at least landing on its belly and sliding along the ground (which is itself a pretty bad situation and people are going to die), there are not likely to be many survivors, or any. You definitely don't want, say, the nose or the tail to take the brunt of the initial impact. Problem is, in most of the &quot;everywhere else&quot; cases, it's really hard to land on the belly and use your landing gear to slow down. Fire, smoke, water, and/or impact will be the death of most people on board in these scenarios.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2432" LastEditorUserId="2432" LastEditDate="2014-10-04T17:55:54.347" LastActivityDate="2014-10-04T17:55:54.347" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8931" PostTypeId="2" ParentId="8907" CreationDate="2014-10-05T00:39:35.877" Score="2" Body="&lt;p&gt;A couple of extra points for piston engine aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The size and amount of propeller blades mostly depends on the power output of the engine. A giant prop on a tiny engine won't be good, because it consumes too much energy just to spin it. Conversely, a small prop on a big engine would waste a lot of the engine output, as the prop would overspeed before the engine reached peak performance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Matching prop size to engine is one of the challenges for designers. As mentioned in the previous answer, it depends on what the aircraft will be used for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, most propellers do not actually move the aircraft by 'pushing' the air behind. If that were the case it would not make any sense to have them on the leading edge of the wing or on the nose - you should place them with clear air behind. The propeller is actually an aerofoil, producing lift using the same principle as a wing. Negative pressure is created on the 'upward' side of the prop, so the propeller 'pulls' the aircraft forward. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-05T00:39:35.877" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8932" PostTypeId="1" CreationDate="2014-10-05T06:05:52.367" Score="26" ViewCount="3375" Body="&lt;p&gt;The Lockheed SR-71 and the (old) Lockheed U-2 were engineered to maintain cabin altitudes in excess of 25000 feet AMSL at an altitude of more than 70000 feet AMSL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in both airplanes, pilots are required to wear space suits which maintain the safe pressurisation and oxygen content anyway. If the space suit develops a pressurisation leak, I think it's unlikely that the very high cabin altitude in these airplanes would buy the pilots any more time to descent to a safe altitude safely as the time of useful consciousness at 25000 feet AMSL is the order of a few minutes. Furthermore, it seems strange that aerospace engineers would install a pressurisation system on the Lockheed U2, an airplane already struggling to be as light as possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why is this pressurisation maintained at such a high altitude in the airplanes?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="19" LastEditDate="2014-10-05T09:43:49.713" LastActivityDate="2017-10-23T18:36:06.417" Title="What is the purpose of the extremely high cabin altitudes in military aircraft?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;military&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8933" PostTypeId="2" ParentId="8932" CreationDate="2014-10-05T07:52:03.513" Score="26" Body="&lt;p&gt;Even the unmanned &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk&quot; rel=&quot;noreferrer&quot;&gt;RQ-4 Global Hawk&lt;/a&gt; has a pressurized compartment. The low air density at altitude would not be sufficient to cool the electronics, so a pressurized electronics compartment had to be added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure, but I expect the same reason required pressurization in the U-2 and the SR-71. The electronics were, besides the pilots, also an occupant of their pressurized cockpits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the pressure of 25.000 ft a human will not stay conscious, but will be able to survive. When the pressure drops below that of 30.000 ft, the breathing reflex will stop. If the pilot initiates a descent when his pressure suit starts to leak, he has a good chance of waking up at lower altitude before the aircraft hits the ground if the cabin can prevent the air pressure from falling to that of ambient air.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14957" LastEditDate="2017-10-23T18:36:06.417" LastActivityDate="2017-10-23T18:36:06.417" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8934" PostTypeId="1" AcceptedAnswerId="8941" CreationDate="2014-10-05T11:41:21.693" Score="8" ViewCount="1469" Body="&lt;p&gt;John T. Downey, who spent 20 years imprisoned in China, was captured when his plane was shot down during an attempted &quot;snatch pickup&quot;. The spy they were supposed to retrieve had been turned by the Chinese, and they were waiting for the plane with anti-aircraft weaponry. This 1951 attempt was the first time the snatch pickup was tried in a war, according to &lt;a href=&quot;http://www.slate.com/articles/news_and_politics/history/2014/09/john_t_downey_cia_agent_captured_by_china_during_the_korean_war_the_story.single.html?src=longreads&amp;amp;utm_content=bufferb073b&amp;amp;utm_medium=social&amp;amp;utm_source=twitter.com&amp;amp;utm_campaign=buffer&quot; rel=&quot;noreferrer&quot;&gt;this article&lt;/a&gt; about John T. Downey:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The snatch pickup was a bizarre maneuver, and an untested one. The&#xA;  process called for an aircraft flying at low altitude to hook a line&#xA;  elevated between two poles. Connected to the line would be a harness,&#xA;  into which an agent would be strapped. The contraption resembled a&#xA;  swingset, if that swingset was designed to be born aloft by a cargo&#xA;  plane. Two men in the back of the plane would operate a pulley,&#xA;  dropping the hook intended to catch the agent and then reeling in the&#xA;  line; both the operators and the pilots required extensive training.&#xA;  Describing the operation in his 1984 book Perilous Missions, a history&#xA;  of CIA covert operations in Asia, William M. Leary writes that the&#xA;  agent was forced to sit impassively in his harness, awaiting possible&#xA;  decapitation, among a litany of other potential injuries. The pickup&#xA;  of Downey’s courier would be the first time the CIA ever carried the&#xA;  plan into action. The Air Force deemed the operation too risky to try.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whatever happened to this technique? Is it used today?&lt;/p&gt;&#xA;" OwnerDisplayName="user3773" LastEditorUserId="247" LastEditDate="2014-10-06T15:11:47.053" LastActivityDate="2016-05-07T23:14:23.343" Title="Are snatch pickups used today?" Tags="&lt;military&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8935" PostTypeId="2" ParentId="2021" CreationDate="2014-10-05T13:07:15.247" Score="15" Body="&lt;p&gt;I am a private pilot, and sometimes, the cellphones cause interference with the radio. Most of the time, cellphones are not a problem, but once in a while, I have to turn mine off because it is causing parasitic noises on the radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how bad it would actually be in a passenger aircraft. But if it is similar to my experience in small aircraft, then it would be easier to just ban cellphones, rather than have a little light (like the seatbelt light) indicating when you can or can't use your phone.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-10-05T13:07:15.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8936" PostTypeId="1" AcceptedAnswerId="8965" CreationDate="2014-10-05T14:37:12.323" Score="9" ViewCount="12732" Body="&lt;p&gt;An A380 has up to 2 decks for passengers and only 1 deck for cargo (for passenger's luggage), whereas a B777 has 1 deck for passengers and 1 deck for luggages. It looks like the volume of luggage per passenger is reduced in a A380 compared to a B777. Is that true? Is the volume of luggage per passenger the same? Is there a method to calculate the volume of the cargo and then to design its shape?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="19" LastEditDate="2014-10-06T16:57:28.190" LastActivityDate="2017-04-01T17:27:32.043" Title="How is the cargo hold volume for passenger aircraft designed?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8938" PostTypeId="1" AcceptedAnswerId="8940" CreationDate="2014-10-05T15:31:04.893" Score="12" ViewCount="1225" Body="&lt;p&gt;Recently I replaced the altitude encoder in my airplane because ATC could not receive my altitude during VFR flight following. Up to that point I had been flying VFR under the class B shelf for some time, and I assume my transponder wasn't transmitting the altitude to ATC. It may have been non-functional for several months.&#xA;Was I causing panic in the control tower because my plane wasn't reporting the altitude, and I wasn't on any ATC frequencies for them to contact me? Can ATC determine my altitude from their ground based radar? Is ATC able to contact VFR airplanes when their transponders/encoders are off, or tuned to the wrong squawk code, or malfunctioning? The transponder is tested every two years, so that is a lot of time for something to go wrong.&lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2014-10-13T16:26:12.160" Title="What does ATC do when a VFR flight in the mode C veil has a malfunctioning altitude encoder or transponder?" Tags="&lt;air-traffic-control&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8939" PostTypeId="1" AcceptedAnswerId="8949" CreationDate="2014-10-05T15:57:20.887" Score="15" ViewCount="9416" Body="&lt;p&gt;I'm flying with American Airlines on a cross-country flight soon and was thinking about bringing along my airband receiver/scanner since it'd be fun to listen to ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like I'd be unable to use it during the flight since any type of radio isn't allowed. I don't see any TSA restrictions on them. Am I safe in assuming that I can bring it along and listen to it in the airport terminal without any trouble with security?&lt;/p&gt;&#xA;" OwnerUserId="567" LastEditorUserId="1467" LastEditDate="2015-04-20T09:05:51.507" LastActivityDate="2018-07-29T15:20:21.393" Title="Can I fly with an airband receiver in the United States?" Tags="&lt;passenger&gt;&lt;airlines&gt;&lt;radio&gt;&lt;tsa&gt;" AnswerCount="5" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8940" PostTypeId="2" ParentId="8938" CreationDate="2014-10-05T16:26:29.120" Score="10" Body="&lt;p&gt;A lot of this has to do with whether or not you're talking to ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If you're talking to ATC&lt;/strong&gt; and your Mode C disappears or goes insane they'll ask you to report your altitude (and if your Mode C altitude reporting is wildly off they'll probably tell you something like &quot;Stop altitude squawk - altitude differs by 500 feet&quot;. This is your cue to take the plane to an avionics shop and have the system checked/serviced, and not to attempt to enter B or C airspace, or fly above 10,000MSL, until its fixed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases ATC will continue to work you in the system until you are clear of the Mode C veil (possibly expediting your exit if having no altitude readout on your target is messing up their day) because it's better to be talking to you than not.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If you're not talking to ATC&lt;/strong&gt; things get a bit more complex:&lt;br&gt;&#xA;If your Mode C altitude readout is &lt;em&gt;missing&lt;/em&gt; ATC will generally report you as &quot;traffic, altitude unknown&quot; to other aircraft and apply lateral separation exclusively (nobody is allowed within the minimum lateral separation distance of your target unless they have you in sight and can maintain visual separation). If/When other pilots spot you ATC will usually ask them for your type and altitude so they have some idea of who you are and what you're doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your encoder or transponder is malfunctioning and reporting an incorrect altitude that's substantially more dangerous: ATC has no way of verifying your altitude other than asking you (or another pilot), so they'll be maintaining separation based on an incorrect altitude. This is why even VFR aircraft equipped with Mode C need an encoder check.&lt;br&gt;&#xA;In this case ATC will find out about a malfunction when you're called as traffic to someone and they respond with &quot;Is that my traffic above/below me?&quot;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2014-10-13T16:26:12.160" LastActivityDate="2014-10-13T16:26:12.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8941" PostTypeId="2" ParentId="8934" CreationDate="2014-10-05T16:44:58.247" Score="6" Body="&lt;p&gt;No, although they were used up into the 1990s. Wikipedia has an article on this - called the &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Fulton_surface-to-air_recovery_system&quot;&gt;Fulton Recovery system&lt;/a&gt;. Your quoted paragraph is incorrect - U.S. Air Force Special Operations Command (AFSOC) did use the system, on modified MC-130s. Despite the danger, Wikipedia only mentions one death using the system, though given the clandestine nature of many of the missions it was used on, it would not be surprising if there were other as yet unrecorded instances of its use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern special operations helicopters have a much greater range, and some, like the MH-53, MH-47, and MH-60, are actually air-refuelable, extending their range. Additionally, the CV-22 Osprey has a much greater range and speed than a traditional helicopter. These improvements in extraction vehicles made the 'skyhook' system obsolete. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;http://gizmodo.com/347064/skyhook-surface-to-air-human-recovery-system-looks-like-craziest-ride-ever&quot;&gt;this article&lt;/a&gt; mentions the British used the system in 2001 to rescue an injured soldier behind enemy lines.&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-10-05T16:44:58.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8942" PostTypeId="2" ParentId="8936" CreationDate="2014-10-05T17:37:36.013" Score="11" Body="&lt;p&gt;The cargo compartments are not only for luggage. Commercial cargo also travel on passenger aircraft, besides cargo aircraft. With luggage alone, there are plenty of spaces in the cargo deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, if you fill all the seats, all the cargo space and sufficient fuel for a long trip in a B777, the plane won't takeoff - its GW (Gross Weight) exceeds the MTOW (Max Take-Off Weight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines are smart people - if a flight is not full, dispatch will put more cargo on the aircraft to utilize it. A lot of passenger airliners also offer air delivery service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some passengers complain, &quot;I can't book the flight. The staff says it's full, yet there are many empty seats!&quot; Commercial cargo yields more revenue than an economy seat. Thus, given the weight limitation, an airline may prefer cargo vs passenger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have info about A380, but I'd guess that the A380 has less extra cargo space than the B777. But as long as it's enough, it isn't a problem.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="5517" LastEditDate="2016-01-25T18:37:17.140" LastActivityDate="2016-01-25T18:37:17.140" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8943" PostTypeId="2" ParentId="8917" CreationDate="2014-10-05T19:42:55.940" Score="3" Body="&lt;p&gt;I would like to add a bit of explanation. It is not the engines that keep aircraft in the air, it is the wings that generate lift as they move through the air. Whether the engines run or not does not affect the lift generation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However as the aircraft moving through air and wings producing lift cause drag that slows the plane down. The engines compensate the drag so the plane can maintain speed. But when the aircraft flies, it also has potential energy due to it's altitude (that had to be provided by the engines during climb) and that can be exchanged for kinetic energy to maintain the speed instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift is significantly higher than the drag, so the plane only needs to descend quite slowly to keep flying. Glide ratio ranges from around 10 for small general aviation planes to around 60 for good sailplane. A typical value for airlines is around 18 which means from the typical cruise altitude of 10km they can glide about 180km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar principle applies even to helicopters. Their rotor only provides lift when it is spinning, but when the engine fails, air flowing diagonally up and aft through the rotor can keep the rotor spinning and providing sufficient lift to maintain controlled descent. This is called autorotation. Helicopters have smaller gliding ratios, around 5, but they can use the energy of the spinning rotor itself to decelerate in the final phase of landing and so they can do vertical landing even with all engines out.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-10-05T19:42:55.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8944" PostTypeId="1" CreationDate="2014-10-05T22:29:41.550" Score="10" ViewCount="346" Body="&lt;p&gt;To the best of my knowledge, Cessna's 182JT-A has not yet been certified. At least I couldn't find on Google any indication that it has. Lots of items that certification is &quot;imminent&quot; but no real facts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet, I see them for sale and YouTube has videos of them flying. Am I correct in believing that it is possible to buy one and then operate it as an experimental aircraft?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="65" LastEditDate="2015-03-20T20:01:00.570" LastActivityDate="2015-05-02T07:46:53.727" Title="Can one purchase a Cessna 182JT-A although it has not yet been certified?" Tags="&lt;general-aviation&gt;&lt;aircraft-certification&gt;&lt;cessna-182&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8945" PostTypeId="1" CreationDate="2014-10-05T23:43:20.407" Score="1" ViewCount="223" Body="&lt;p&gt;I recently got my private pilot license and will soon be taking people for rides. My son wants to get his license (he passed his written test), so I was thinking I could introduce him so basic maneuvers. As a pilot, but not an instructor, what can I safely let a non-pilot do? Obviously anything in the pattern will require myself to be in control, but is it OK for a non-pilot to do slow flight or steep turns? Or would it be better to just perform them myself and let them see how its done? As pilot in command, it comes down to what I feel is safe, but are there any regulations that prevents a passenger from taking the controls and doing some turns? I don't remember this being covered in ground school or any of the training books.&lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2014-10-05T23:43:20.407" Title="What maneuvers can a non-pilot perform when flying with a private pilot?" Tags="&lt;flight-training&gt;&lt;general-aviation&gt;&lt;passenger&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2014-10-06T12:46:37.683" ContentLicense="CC BY-SA 3.0" />
  <row Id="8947" PostTypeId="2" ParentId="8000" CreationDate="2014-10-06T00:30:57.277" Score="88" Body="&lt;p&gt;This is how I explain it, hopefully it helps more than hinders!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Heading:&lt;/strong&gt;&lt;br&gt;&#xA;This is where my nose points - and seeing as my nose is attached to my head, this is where my head (and thus my machine) is pointing relative to North.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Course:&lt;/strong&gt;&lt;br&gt;&#xA;This is my INTENDED path of travel that I have calculated taking into consideration winds, variation and declination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Track:&lt;/strong&gt;&lt;br&gt;&#xA;This is my ACTUAL path traveled over ground - just like a set of tracks I would leave behind in the snow or sand, relative to North &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bearing:&lt;/strong&gt;&lt;br&gt;&#xA;This is the angle &lt;em&gt;between&lt;/em&gt; the location of an object, machine or destination &lt;em&gt;and&lt;/em&gt; either:&lt;br&gt;&#xA;- my heading. This is called 'Relative Bearing'.&lt;br&gt;&#xA;- or magnetic  north (direction toward the magnetic north pole). This is called 'Magnetic Bearing'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Xqzo.jpg&quot; alt=&quot;Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So from the picture, if I take off from Springfield enroute to Shelbyville. My &lt;strong&gt;course&lt;/strong&gt; (the intended path) is due East, or 090 degrees. I notice my winds are Southerly (from 183 degrees / to 003 degrees), so I make my &lt;strong&gt;heading&lt;/strong&gt; 095 degrees to compensate for wind drift (or 5 degrees crab into the wind).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If my calculations are bang on, my &lt;strong&gt;track&lt;/strong&gt; should be the same as my &lt;strong&gt;course&lt;/strong&gt;, however I misjudged the winds, finding out my resulting &lt;strong&gt;track&lt;/strong&gt; over the ground is 081 degrees - I must correct (by increasing) my &lt;strong&gt;heading&lt;/strong&gt; to get back on &lt;strong&gt;course&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now with some airports, the navaids (NDB or VOR) are not directly at the airfield but some distance away, so if I wanted to either fly directly to the NDB or figure out my position in space during enroute nav checks, I would take the bearing to the NDB/VOR either relative to my &lt;strong&gt;heading&lt;/strong&gt; or relative to magnetic north to find its position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;" OwnerUserId="3787" LastEditorUserId="128" LastEditDate="2015-10-16T06:00:06.793" LastActivityDate="2015-10-16T06:00:06.793" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8948" PostTypeId="1" AcceptedAnswerId="8964" CreationDate="2014-10-06T02:17:16.713" Score="8" ViewCount="805" Body="&lt;p&gt;So Uncle Bob just died and left me 3.14 million dollas.  Or else I hit the lottery, or what have you.  Whatever the case may be, I've decided that today is the day I buy myself an airplane.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Harrison_Ford#Aviation&quot; rel=&quot;nofollow&quot;&gt;Harrison Ford has one&lt;/a&gt; and by God I want one too.  This means that I need a mechanic.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can assume that I don't &lt;em&gt;already&lt;/em&gt; know any mechanics (For the purposes of the question, we can assume I soaked my home in &lt;a href=&quot;http://en.wikipedia.org/wiki/Cristal_%28wine%29&quot; rel=&quot;nofollow&quot;&gt;Cristal&lt;/a&gt;, tossed flaming $100 bills at it until it burned down, and then moved to Beverly Hills, away from all the little people), so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How do I find a mechanic or maintenance shop to keep my privately-owned aircraft airworthy?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="64" LastEditDate="2014-10-06T20:41:43.500" LastActivityDate="2014-10-06T20:41:43.500" Title="How do I select an aircraft mechanic?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-ownership&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8949" PostTypeId="2" ParentId="8939" CreationDate="2014-10-06T02:21:07.627" Score="15" Body="&lt;p&gt;This is probably more &lt;a href=&quot;https://travel.stackexchange.com/questions/2322/can-i-listen-to-air-traffic-control-on-a-flight&quot;&gt;a travel question&lt;/a&gt; than an aviation one, but I did some Googling of various aviation and travel sites and the consensus seems to be this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You can carry the scanner with you, but if you're unlucky and encounter the wrong TSA agent on the wrong day then you may be asked a lot of questions at security (the &lt;a href=&quot;http://www.tsa.gov/&quot; rel=&quot;noreferrer&quot;&gt;TSA's&lt;/a&gt; &quot;Can I Bring...&quot; tool seems to consider scanners to be generic electronic items)&lt;/li&gt;&#xA;&lt;li&gt;Using the scanner while sitting in the airport is fine, but if you attract attention to yourself then you may be questioned by the police or airport security&lt;/li&gt;&#xA;&lt;li&gt;You may not use a two-way radio on board the aircraft, because they're specifically required to be off at all times (this is in every airline's safety instructions that I've seen); that shouldn't apply to a radio that only receives but the cabin crew might ask you to turn it off anyway if they're not sure about it&lt;/li&gt;&#xA;&lt;li&gt;Even if you did operate the scanner in the air, the reception is terrible and you'll probably hear only the aircraft's crew, not ATC&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that this information is for the USA only, many other countries are very strict about possession and use of scanners or two-way radios and in the UK (for example) just &lt;a href=&quot;http://www.liveatc.net/faq/&quot; rel=&quot;noreferrer&quot;&gt;listening to ATC is actually illegal&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2014-10-06T09:49:41.197" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="8950" PostTypeId="1" AcceptedAnswerId="8954" CreationDate="2014-10-06T03:27:08.633" Score="37" ViewCount="15346" Body="&lt;p&gt;A car can be towed by a tow truck to the repair shop when it breaks down on the highway. Is it possible for a passenger plane to be towed by an emergency tow plane along the air corridor to the next nearest airport assuming it cannot reach there on its own power (example if it runs out of fuel or both pilots are incapacitated)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update:&#xA;This question actually consist of two parts. Whether it is feasible and whether this is practical. I have seen a small tugboat towing a barge; a man pulling a firetruck. Before writing off this idea completely, can someone address what's stopping a fighter plane from towing a passenger jet if a proper point of harness is installed?&lt;/p&gt;&#xA;" OwnerUserId="1390" LastEditorUserId="14897" LastEditDate="2019-09-08T15:50:17.927" LastActivityDate="2019-09-08T15:50:17.927" Title="Can a passenger jet be towed to safety if it breaks down in midair?" Tags="&lt;airliner&gt;&lt;emergency-procedures&gt;&lt;towing&gt;" AnswerCount="12" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8951" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T04:41:54.737" Score="9" Body="&lt;p&gt;Its not unheard of - gliders are often carried up by tow planes. However, hitching up a plane on the ground and towing it up is completely different than trying to do the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Catching up to a plane flying at great speed.&lt;/li&gt;&#xA;&lt;li&gt;Positioning yourself in front of it.&lt;/li&gt;&#xA;&lt;li&gt;Hooking up a tow hook.&lt;/li&gt;&#xA;&lt;li&gt;Pulling it fast enough to maintain flight.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Suppose you were somehow able to do the first 4, you are still left with the small point of having to &lt;em&gt;land two aircraft that are tied to each other&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So its is nearly impossible to do what you are suggesting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane will maintain flight as long as there is sufficient lift on the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To tow a disabled plane is really not required, because even if all engines fail (a highly unlikely event), there are contingencies in place to power the control surfaces and communications so that the pilot can glide the plane to a safe landing. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/8917/if-a-typical-passenger-plane-had-total-failure-of-all-engines-mid-flight-is-it&quot;&gt;this question&lt;/a&gt; for examples of incidents where all power was lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets assume that everyone on board becomes incapacitated. In this scenario (which has happened before) the plane will continue on its programmed flight path until it runs out of fuel, at which point it will drop in altitude eventually until it crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In April 2012 the pilot of a Cessna 421 was incapacitated (possibly due to hypoxia - lack of oxygen) - the aircraft continued on its programmed course until it eventually ran out of fuel (flightaware flight track):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MKNIp.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;September 10 had another &lt;a href=&quot;http://edition.cnn.com/2014/09/05/us/norad-air-threat/&quot; rel=&quot;nofollow noreferrer&quot;&gt;similar incident&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-10-06T06:08:26.947" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="8952" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T04:59:30.090" Score="27" Body="&lt;p&gt;I am picturing something like a 777 being towed due to a complete engine failure.  Please correct me if you had something else in mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is unheard of, but it would be possible, and is a very interesting thought.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing that comes to mind is something like a C-17 being refueled by a KC-135&#xA;&lt;img src=&quot;https://i.stack.imgur.com/stl3g.jpg&quot; alt=&quot;midair refueling&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, a loaded 777 will weigh more carrying passengers than a C-17 loaded with cargo, but these mid-air refueling operations, logistically, are not much different that what would be needed to tow an airborne plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the differences I can think of - whether or not they are feasible, I'm not sure.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Logistically: the air force has their rendezvous planned down to a couple seconds before the plane that needs fueling is even airborne.  In an emergency situation everything from planning to execution would have to happen in a VERY small amount of time.&lt;/li&gt;&#xA;&lt;li&gt;When refueling, no major tension is put on the refueling hose.  If a 777 were being towed the tension would be AT LEAST the amount of air resistance acting on the 777.&lt;/li&gt;&#xA;&lt;li&gt;Designing a hook that can bear the huge forces and moments involved would take a lot of work.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I did a little math to calculate the forward force that would be required to pull a (fully loaded) 777 to keep it above stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would need about 43,000lbs - which is not too much in the world of airliners. For example, the 777 has a take off weight of 660,000lbs - and each engine produces over 100,000lbs of thrust.  So it would be very easy to have a well equipped aircraft or two to tow a 777 - once connected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The total force in the rope, assuming the towing airplane is slightly above the airplane being towed would simply be &lt;code&gt;42,500lb/cos(angle)&lt;/code&gt; so if the length of the rope is a generous 300ft and the towing airplane is 50ft above the towed aircraft, then the total force would be 43,100lb.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/dtg9B.png&quot; alt=&quot;equations in Mathematica&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just in case people don't trust my numbers, here's a screenshot of the math.  I had a 777 model on my computer that I used to get the data from:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/krfmL.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/krfmL.png&quot; alt=&quot;more equations in Mathematica&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="3949" LastEditDate="2016-03-31T00:50:51.367" LastActivityDate="2016-03-31T00:50:51.367" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="8954" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T07:26:36.753" Score="108" Body="&lt;p&gt;Towing is quite feasible, and even landing while in tow is possible - I've done it myself in gliders. The hard part is catching up with the stricken plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To stay with Keegan's Boeing 777: It most likely will travel at Mach 0.8 and somewhere between 30.000 and 39.000 ft when disaster strikes. Let's further assume that power fails instantly, so the aircraft, traveling at 240 m/s, will develop a sink rate of 15 m/s just to continue flying. When it sinks, the increasing density allows it to slow down, so at sea level it will fly at 130 m/s, sinking with 8.125 m/s. For simplicity, assume a linearly decreasing sink rate, and the remaining time aloft will be less than 1000 sec or around a quarter of an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the towplane has 15 min to scramble the crew, run up the engines, get take-off clearance and to actually fly an intercept to the stricken airliner. How realistic is that? How many airports are needed to have 777-sized towplanes ready, and how many otherwise unproductive 777s would this scheme need?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A car can stop and wait a couple of hours for the tow to reach it. An aircraft can not.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-06T07:26:36.753" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="8955" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T08:03:58.860" Score="7" Body="&lt;p&gt;Cars and passenger aircraft are designed and maintained in very different ways.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Redundancy&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Cars only have one engine, unlike almost the aircraft that carry most passengers. Cars cannot continue their journey if their only engine breaks down or if an axle breaks. Aircraft have multiple independent sets of many of the most critical parts like engines and flight control systems, they are specifically designed to be able to continue when many things break down. An aircraft can continue when one engine breaks down, it can still be flown and make a landing when all engines have broken down. Aircraft have redundant systems to allow for continued operation after multiple failures.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Maintenance and monitoring&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Cars might only be looked at by a qualified mechanic once a year or once every 18 months. Even at this time, it is likely that they mechanic just changes the oil in the engine, checks the fluid levels and brake wear and does a few other basic checks specified by the manufacturer. They don't check everything in the car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft is more likely to be monitored continuously. It is not unusual for the engines to be sending data to the engine-makers in flight so that the engine makers can measure the health of the engine and can predict when the engine needs maintenance before any problem arises for the aircrew. After every flight, the crew of an aircraft report any unusual behaviour of the aircraft to the maintenance crew so that incipient problems can be dealt with before there is any danger of breakdown.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=1W5PCYFXLJ4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Car owners are not this diligent&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Towing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Cars are expected to break down and are designed to be towed. Aircraft are maintained so that they don't need this and the airframes are not designed to be towed in the air, there is no towing point with enough strength other than that designed into the landing-gear for gentle low-speed towing on the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot attach a towline to an aircraft that is not under good control, if the pilots are incapacitated or if the aircraft is damaged such that steady flight is impossible (e.g. phugoid cycles etc). If the aircraft is under good control it is probably able to fly or glide to an alternate airfield or attempt an emergency landing. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Time is of the essence&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Say a 747 lost all four engines, there would probably not be enough time to launch a rescue tow-aircraft from a nearby airport and reach the plane in time to do anything useful in mid air. Particularly if the 747 is in mid-Pacific or flying through a volcanic ash-cloud. It is better to design the aircraft to cope as well as we can make it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A car can wait an hour or two at the side of the road. An aircraft cannot wait.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="755" LastEditDate="2017-12-15T21:09:48.703" LastActivityDate="2017-12-15T21:09:48.703" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8956" PostTypeId="2" ParentId="8948" CreationDate="2014-10-06T08:39:13.007" Score="1" Body="&lt;p&gt;I believe the best way to seek such a mechanic would be to ask the place you purchased your aircraft, asking the airfield you park your aircraft at or simply googling &quot;Aircraft Mechanic in [insert location]&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://lmgtfy.com/?q=local%20airplane%20mechanics%20in%20my%20area&quot; rel=&quot;nofollow&quot;&gt;If you need a link to local mechanics here is one.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3103" LastActivityDate="2014-10-06T08:39:13.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8957" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T09:02:45.000" Score="15" Body="&lt;p&gt;If both pilots are incapacitated, towing the plane is moot because it won't be able to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of fuel starvation, an airliner that loses its engines at cruise altitude can glide for maybe 20&amp;ndash;25 minutes before it descends to sea level. If there was an airport close enough to scramble a rescue plane from, then the broken plane would have a decent chance of just gliding to a landing at that airport.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-10-06T09:02:45.000" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8958" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T09:29:11.330" Score="8" Body="&lt;p&gt;The simple answer is that it's presently not possible, certainly not for large passenger jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it's possible to do rather impressive things like towing a glider or setting up a rendez-vous in mid-air for refueling. Towing would therefore not seem completely out of the realms of possibilities and Keegan's calculations suggest it would even theoretically be plausible (I didn't try to verify the calculations and I am probably not knowledgeable enough to do so).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One problem is that if all engines fail, staying put and waiting for a tow is not an option. Fortunately, planes do not “fall off the sky” either, they can glide in a controlled fashion and that's the actual contingency plan. It has &lt;a href=&quot;https://aviation.stackexchange.com/questions/8917/if-a-typical-passenger-plane-had-total-failure-of-all-engines-mid-flight-is-it&quot;&gt;happened before&lt;/a&gt;, perhaps most famously to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gimli glider&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Pieter Kämpf explained, an additional problem in this situation is that, while it's possible to fly the plane to safety, there is not much time available. Imagining a tow plane is one thing, but having one at the ready to reach a specific point anywhere in the world in 10-20 min is something else entirely and would be prohibitively expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if the pilots are incapacitated, things are quite different. Modern planes can maintain speed and altitude and basically continue to fly. This has also happened before, e.g. to &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helios Airways Flight 522&lt;/a&gt; and in that particular case there was more than enough time for fighter jets to reach the distressed airliner and escort it for over half an hour. Ultimately, however, they couldn't do anything else than watch it run out of fuel and crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is that “towing” in some way or other is neither needed nor helpful. After all the plane is still entirely capable of flying on her own. What you need is taking control and that's presently not possible either. To my (non-expert) eyes, adding some remote control functionalities seems perfectly doable with current technology (cf. drones) but that would mean adding additional complexity, potential for failure, etc. I assume the cost/benefit analysis does not justify it and, as far as I know, there is no commercial passenger plane with anything like that.&lt;/p&gt;&#xA;" OwnerUserId="3018" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-10-06T11:32:29.173" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8959" PostTypeId="2" ParentId="8948" CreationDate="2014-10-06T09:31:13.640" Score="3" Body="&lt;p&gt;It's very, very easy to hire an aircraft mechanic. Drive to your local airport and explore the less-travelled roads beside the fence. You will find a number of maintenance facilities that can service anything from a Piper Cub to the Concorde. Walk in, say hello.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small exception: major international hubs tend to be air carrier only. General aviation will be somewhere else, but any maintenance shop will know where the others are - it's a fairly small community.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that uncle Bob's 3.14 million won't buy much. It will get you a really decent piston single or very light twin. Or a high-time turbine in need of some pricy maintenance. Remember that unlike a car, the sticker price on an aircraft is just the edge of the money pit. You make yourself a 5-year budget and spend no more than half on the actual aircraft. If you buy new you can shift it a bit as you won't need any unscheduled maintenance for a while but in the broad scheme of things aviation is not for the financially fainthearted.&lt;/p&gt;&#xA;" OwnerUserId="2590" LastActivityDate="2014-10-06T09:31:13.640" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8961" PostTypeId="2" ParentId="8950" CreationDate="2014-10-06T16:25:32.410" Score="2" Body="&lt;p&gt;There has to be consideration for whether the towing process would remain at a stable altitude, or just provide assist to the nearest airport, calling into question the amount of power that would be required to assist. Given the amount of turbulence that would be generated from the towing craft (and the bigger it is, the worse it would be) it seems unlikely the disabled aircraft would be able sustain stable flight and structural integrity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also need to consider the relatively small number of aircraft that become completely &quot;disabled&quot; without being impacted by some related catastrophic event that otherwise compromises it's flight worthiness. There are very few instances of US Air 1549 and most would be too close to the ground to allow any time to react without the famed Star Trek Tractor Beam&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps with a highly specialized design process some of the challenges could be overcome, but the practicality of being able to actually have the proper assistance available would negate the feasibility.&lt;/p&gt;&#xA;" OwnerUserId="3800" LastActivityDate="2014-10-06T16:25:32.410" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8962" PostTypeId="2" ParentId="8936" CreationDate="2014-10-06T16:54:10.593" Score="10" Body="&lt;p&gt;Cargo compartments in airliners are generally in two categories: regular cargo and bulk cargo. This graphic shows the compartments in a 777.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sGbDM.jpg&quot; alt=&quot;777 cargo holds&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The normal cargo compartments are generally filled with containers called Unit Load Devices. These are standard containers that can be filled with cargo and easily loaded/unloaded from the cargo compartment. Palletized cargo can also be loaded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ARo8q.jpg&quot; alt=&quot;Some LD containers&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bulk cargo compartment is for non-containerized cargo like loose luggage. You can see that the majority of cargo space is reserved for non-bulk cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the A380, there is a large bulk hold as well as plenty of room for other cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/irzwd.jpg&quot; alt=&quot;A380 cargo holds&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-06T16:54:10.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8963" PostTypeId="2" ParentId="8948" CreationDate="2014-10-06T20:00:01.313" Score="0" Body="&lt;p&gt;FAA has maintains a &lt;a href=&quot;http://av-info.faa.gov/repairstation.asp&quot; rel=&quot;nofollow&quot;&gt;list of mechanics&lt;/a&gt;. You can download the entire list too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/mechanics/&quot; rel=&quot;nofollow&quot;&gt;This page&lt;/a&gt; has some related information about mechanics.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-10-06T20:00:01.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8964" PostTypeId="2" ParentId="8948" CreationDate="2014-10-06T20:39:08.273" Score="7" Body="&lt;p&gt;The key when selecting an aviation mechanic or shop to maintain your newly purchased plane is &quot;time in type&quot;: You would not take a Cessna 172 to the United Airlines maintenance facility at JFK, not would you take an A380 to the local Cessna service center (even though it would be perfectly legal to do so).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're buying a new aircraft (of any type) the manufacturer will be able to recommend an authorized service center for you, and you'll probably want to use an authorized service center (especially for warranty work).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're buying a used aircraft you can still contact the manufacturer and ask about authorized service centers. They will usually be happy to give you a list of places near you that can work on your aircraft, and who are blessed by the factory to perform warranty service, complete mandatory service bulletins where the manufacturer is supplying parts / covering labor, etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aside from manufacturer recommendations there are a lot of other ways to find a maintenance shop that beat simply asking Google and picking one at random.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the most common single-engine piston aircraft (your typical Piper Cherokee, Cessna 172/182, etc.) you can almost certainly find a mechanic at your local general aviation airport - ask the FBO where you're storing the plane for recommendations or talk to other pilots on the ramp about who they use for maintenance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more esoteric aircraft (high-performance singles, twins, vintage/classic/warbirds, etc.) your best resource is often a type club (e.g. &lt;a href=&quot;http://www.bonanza.org&quot;&gt;The American Bonanza Society&lt;/a&gt; for Beechcraft Bonanzas, or &lt;a href=&quot;http://www.comancheflyer.com/NS/index.php&quot;&gt;ICS&lt;/a&gt; for the Piper Comanche) - Google can help you track down a type club, and the members can help you find mechanics who have experience working on your particular airplane.&lt;br&gt;&#xA;Type clubs are also a great source of other information (like where to find parts). &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-10-06T20:39:08.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8965" PostTypeId="2" ParentId="8936" CreationDate="2014-10-06T20:45:39.613" Score="11" Body="&lt;p&gt;The cargo hold volume is a secondary result of the design process. Pressurized fuselages need to be round for best structural efficiency, and the passenger compartment needs to be high enough for passengers to stand upright. The rest has to follow from that, and the old narrow-body aircraft (like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-8&lt;/a&gt; or the Boeing 707) were mostly volume-limited (which means that they would have benefited from more internal volume), whereas the early wide-bodied aircraft (&lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A300&quot; rel=&quot;nofollow noreferrer&quot;&gt;A300&lt;/a&gt;, Boeing 747) are weight-limited (which means operators flew them with some volume unfilled to avoid overloading the plane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GzGgV.gif&quot; alt=&quot;fuselage cross sections of the A310 and the B737 in comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture shows the fuselage cross section of an A310 (left) and a Boeing 737 (right), which are typical for wide-bodied rsp. narrow-bodied designs. Note the relatively bigger freight compartment of the Airbus fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even bigger fuselages than those of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 777&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_MD-11&quot; rel=&quot;nofollow noreferrer&quot;&gt;MD-11&lt;/a&gt; offer so much internal volume that two passenger decks are needed to avoid flying lots of empty space around. McDonnell-Douglas planned for a while to &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_MD-12#MD-XX&quot; rel=&quot;nofollow noreferrer&quot;&gt;expand the passenger load of the MD-11&lt;/a&gt; by adding a lower passenger deck forward of the wing, and Airbus did the logical thing and designed the A380 from the outset as a double-decker. &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_KR-860&quot; rel=&quot;nofollow noreferrer&quot;&gt;Other designs of a similar size&lt;/a&gt; came to the same conclusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that cargo volume on &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777#777-200LR&quot; rel=&quot;nofollow noreferrer&quot;&gt;long-range&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400#747-400ER&quot; rel=&quot;nofollow noreferrer&quot;&gt;variants&lt;/a&gt; of &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A330#A330-300HGW&quot; rel=&quot;nofollow noreferrer&quot;&gt;several&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10#Longer-range_variants&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft&lt;/a&gt; is reduced because a fuselage tank had to be added aft of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases the cargo volume was determined by what was left unfilled.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-04-01T17:27:32.043" LastActivityDate="2017-04-01T17:27:32.043" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8966" PostTypeId="1" CreationDate="2014-10-07T00:42:22.190" Score="17" ViewCount="10412" Body="&lt;p&gt;A flight simulator system company has a system that they say lets you &quot;Log IFR Currency without an Instructor.&quot; Can someone explain to me how exactly that works?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does that mean that an Instrument rated pilot only needs a simulator to stay current?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I am not a pilot so I don't know about currency requirements. I'm just curious.&lt;/p&gt;&#xA;" OwnerUserId="3806" LastEditorUserId="97" LastEditDate="2015-05-03T00:44:35.900" LastActivityDate="2019-06-02T22:55:50.487" Title="Is it possible to log IFR currency in a flight simulator without an instructor?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-simulator&gt;&lt;currency&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8968" PostTypeId="2" ParentId="8939" CreationDate="2014-10-07T02:03:03.900" Score="7" Body="&lt;p&gt;In the US, it's perfectly legal to bring an airband receiver or scanner through security and on to an airplane. There are restrictions on using radios (even if receive only) onboard an aircraft. Furthermore, you are required by the FAA to comply all pilot and flight attendant instructions (and they usually say turnoff all radios).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is however a possible loophole by using a crystal radio. There's no rule against taking one onboard an airplane, and since there's no battery, it's impossible to turn off. Do a search for &quot;airband crystal radio&quot; for possible receivers and designs.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2014-10-07T02:03:03.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8969" PostTypeId="1" AcceptedAnswerId="8970" CreationDate="2014-10-07T03:11:10.577" Score="7" ViewCount="3303" Body="&lt;p&gt;I am going from KPRC to KVGT with a friend in his C-182.  I don't have a high-performance endorsement, but can I -- as a private pilot -- log as SIC at any time during our flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what rules do I have to follow?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I understand:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I can log SIC time since the aircraft is a SEL&lt;/li&gt;&#xA;&lt;li&gt;I can't log landings, obviously&lt;/li&gt;&#xA;&lt;li&gt;And SIC time really doesn't mean anything&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Am I right in assuming those things?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="1696" LastEditDate="2015-04-27T19:16:17.347" LastActivityDate="2015-04-27T19:16:17.347" Title="What are the requirements for logging SIC time?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8970" PostTypeId="2" ParentId="8969" CreationDate="2014-10-07T04:21:50.887" Score="10" Body="&lt;p&gt;You can basically log SIC time if you are a &lt;strong&gt;&lt;em&gt;required crewmember&lt;/em&gt;&lt;/strong&gt; and are not able to log PIC time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, generally in an airplane like a C-182 which is certified for only one pilot, you can't log SIC time because you aren't a required crewmember.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few exceptions though, like being a safety pilot for the PIC while they are using a view limiting device (like an IFR hood), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SIC time is not pointless because it still adds to your total time! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as landings, you can log them only if you are the sole manipulator of the flight controls, in which case you are allowed to log &lt;strong&gt;PIC&lt;/strong&gt; time (even though you aren't allowed to &lt;strong&gt;act&lt;/strong&gt; as the PIC since you don't have your high performance endorsement).  Oddly enough, in this situation the pilot who is acting as PIC isn't allowed to log it because they don't meet any of the requirements for doing so. It's one of the only situations where the PIC isn't allowed to log it as such.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-10-14T21:46:51.253" LastActivityDate="2014-10-14T21:46:51.253" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8971" PostTypeId="1" AcceptedAnswerId="8974" CreationDate="2014-10-07T07:47:40.310" Score="3" ViewCount="1076" Body="&lt;p&gt;I frequently fly within India as part of my work and every time I am sitting in an airliner preparing to take off, I observe a lot of differences in each crew handling the take off or the ground crew procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to understand if there is any board that certifies these crews and airlines for safety, like the FAA for the US, if these information are released to the public, like a certificates that are issued for public information.&lt;/p&gt;&#xA;" OwnerUserId="3807" LastEditorUserId="97" LastEditDate="2015-05-03T00:42:54.953" LastActivityDate="2015-05-03T00:42:54.953" Title="Who is India's equivalent of the FAA?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;dgca-india&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="8972" PostTypeId="5" CreationDate="2014-10-07T08:35:38.973" Score="0" Body="&lt;p&gt;Every ICAO member state has a Civil Aviation Authority which deals with implementing international and national aviation regulations. In India the &lt;a href=&quot;http://dgca.nic.in/&quot; rel=&quot;nofollow&quot;&gt;Directorate General of Civil Aviation&lt;/a&gt; (DGCA) is fulfilling this function.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-07T09:33:43.697" LastActivityDate="2014-10-07T09:33:43.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8973" PostTypeId="4" CreationDate="2014-10-07T08:35:38.973" Score="0" Body="DGCA Directorate General of Civil Aviation is the Civil Aviation Authority of India." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-07T08:35:38.973" LastActivityDate="2014-10-07T08:35:38.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8974" PostTypeId="2" ParentId="8971" CreationDate="2014-10-07T08:43:17.677" Score="6" Body="&lt;p&gt;This regulatory oversight is performed by the Civil Aviation Authority of a country. In India, this function is performed by the &lt;a href=&quot;http://dgca.nic.in/&quot; rel=&quot;nofollow&quot;&gt;Directorate General of Civil Aviation&lt;/a&gt; (DGCA-India). Typically certification information is available to the public, but only high level information will be given. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Searching on the DGCA-India website I found &lt;a href=&quot;http://dgca.nic.in/cars/D7M-M1.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; that lays down the requirements on Cabin Crew Training. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-07T09:15:48.673" LastActivityDate="2014-10-07T09:15:48.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8975" PostTypeId="1" CreationDate="2014-10-07T10:17:34.767" Score="2" ViewCount="138" Body="&lt;p&gt;I was wondering the differences between fluid patterns and their consequences when a delta wing is straight and yawed slightly. Thank you.&lt;/p&gt;&#xA;" OwnerUserId="3809" LastActivityDate="2014-10-07T10:17:34.767" Title="Delta wing flow patterns (straight and yawing)" Tags="&lt;aerodynamics&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2014-10-08T00:51:47.107" ContentLicense="CC BY-SA 3.0" />
  <row Id="8976" PostTypeId="2" ParentId="8950" CreationDate="2014-10-07T13:22:17.730" Score="3" Body="&lt;p&gt;The OP asks about towing and this has been comprehensively explored in the preceding answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, we could widen the discussion by fitting the stricken aircraft with a docking mechanism on the underside. Then the rescue aircraft (with a matching docking unit on the top side) could maneuver beneath it and lock on. We would then have a composite structure like the 747-space shuttle transporter configuration. A sufficiently powerful rescue ship could then fly the pair down to a safe landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further enhancements occur: (a) The docking port could have a manhole through which the PAX could be evacuated into the rescue ship. (b) A command-interface could enable the rescue pilot to control the flight surfaces on the stricken plane (assuming they were still functional), thus making it easier to fly.&lt;/p&gt;&#xA;" OwnerUserId="3811" LastActivityDate="2014-10-07T13:22:17.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8977" PostTypeId="1" CreationDate="2014-10-07T13:38:53.830" Score="2" ViewCount="210" Body="&lt;p&gt;When travelling in an international flight, you pass a border with passport check at both the departure and the arrival airports. It means you spend time in an international area. What are the applicable laws in this area? The one from the country the airport is located in? A special set of international laws? &#xA;Are you juridically out of any country (as if in international waters)? Is there special status with flights between countries with special immigration agreements (e.g. Shengen area)?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2014-10-07T13:38:53.830" Title="In an international airport, is there specific set of laws for the international area?" Tags="&lt;airport&gt;&lt;international&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-10-07T15:33:04.907" ContentLicense="CC BY-SA 3.0" />
  <row Id="8978" PostTypeId="2" ParentId="8950" CreationDate="2014-10-07T13:56:56.880" Score="3" Body="&lt;p&gt;There are several reasons that this idea would not be practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An gliding aircraft flying at around 30,000ft would have, say, 20 mins before it hits the ground. If there is a suitable airfield within that range it stands a decent chance of landing safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stricken aircraft would be travelling at, say, Mach 0.8 so only a fast fighter jet would be capable of chasing and catching it from behind in the available time. Any other rescue aircraft would have to approach from the front, circle and manoeuvre into position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time constraint makes this almost impossible. Assuming the rescue aircraft took 10 mins to prepare and take off, then the manoeuvring and attachment of the tow could add another 5 mins. That would allow only a few minutes to actually catch the stricken aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders are designed to be very light aircraft and get towed up by relatively powerful tugs. They then release the tow - it is not re-attached! The airframe of a glider is designed to take the forces involved in towing; that of a passenger aircraft is not. Would it be possible to re-design all passenger planes to cope with this very unlikely scenario of total engine failure without adding weight and reducing efficiency? I doubt it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned by David Richerby, air-to-air refuelling is currently a very expert skill practised by a handful of the best Air Force pilots. Some cunning new technology would be needed before the principle could be used on commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rather than this idea, a more useful and practical suggestion might be to add some sort of remote control function to be used in the case of the pilots becoming incapacitated or terrorists taking over the aircraft. Such technology would need to  be robustly fail-safe and many crashes have shown that that isn't easy to achieve.&lt;/p&gt;&#xA;" OwnerUserId="3810" LastActivityDate="2014-10-07T13:56:56.880" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8980" PostTypeId="1" AcceptedAnswerId="8988" CreationDate="2014-10-07T18:31:19.403" Score="16" ViewCount="2769" Body="&lt;p&gt;Considering it is nearly undetectable on radar, it seems like it wouldn't have to worry about radar guided missiles; in addition to this it is sure to have sophisticated jamming capabilities. So why carry chaff? Just weight.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="15311" LastEditDate="2017-12-21T11:23:35.843" LastActivityDate="2017-12-22T16:37:20.883" Title="Does the F-22 (or any other stealth aircraft) carry chaff?" Tags="&lt;military&gt;&lt;radar&gt;&lt;stealth&gt;&lt;f-22&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="8981" PostTypeId="2" ParentId="8934" CreationDate="2014-10-07T19:58:46.017" Score="2" Body="&lt;p&gt;Perhaps a different answer than what you're looking for, but this summer I watched a banner tow plane do a number of passes attempting to hook their banner.  The set-up is quite like you described: two poles with a rope between them that was attached to the banner; the plane was towing a rope with a hook, and it made a number of low passes attempting to snag the banner.&lt;/p&gt;&#xA;" OwnerUserId="2791" LastActivityDate="2014-10-07T19:58:46.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8983" PostTypeId="2" ParentId="586" CreationDate="2014-10-07T22:22:16.210" Score="0" Body="&lt;p&gt;Simply put: your description of the 60% is WRONG!  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 135.385b does not speak to geography, it speaks to performance!  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Effective length of runway&quot; is not a percentage of real estate, but actually a performance number.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane performance section of the AFM will provide the landing distance given the applicable condition(s). It is this number that derives the &quot;effective runway landing distance.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the regulation stipulates (without going into: zero wind, expected wind, or anticipated wind), the performance number is divided by .60 for 60 percent, or .80 for 80 percent.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the effective length of the runway is measured against a point where the approach path clearance plane (APCP) intersect the threshold to the end of the runway. &#xA;Since the APCP is a 20:1 slope flown at 1.3 VSO, and flown 50 feet above the APCP, the math is simple: 20x50=1,000 feet.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 1,000 feet is where the wheels are expected to touchdown and is accounted for when you calculate the distance by dividing the AFM landing distance by 60 or 80 percent. The effective runway landing distance is within the entire length of the runway, not 60% or 80% and where the APCP intersects the threshold to the published end of the runway. If the runway is displaced, the displacement is accounted for in the effective runway distance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While your reported procedure is close to accurate, it is not the proper method for determining Parts 135.385b or 135.377.&lt;/p&gt;&#xA;" OwnerUserId="3814" LastEditorUserId="2171" LastEditDate="2014-10-07T22:29:15.930" LastActivityDate="2014-10-07T22:29:15.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8985" PostTypeId="2" ParentId="3300" CreationDate="2014-10-08T01:40:50.797" Score="1" Body="&lt;p&gt;There are heavier-than-air firefighting (mine service, etc.) lift frames with four lift props. Ones without whose adaptations and use cases one would find rides:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitchy; trim requires pitching or rolling the crew, or at least jinking the evacuee 'hard mount.'&#xA;Blendy; Four sources of chop, no particular service cowling (emergency fixup, water landing kit, etc.) in air or not, or guarantee of no inflow at ground.&#xA;Noisy; reaction lift is from outer extent of blades; perhaps orbit of blades can be altered to optimize pattern?&#xA;Harder to service-harden by 3x or more (for commercial suitability, nevermind commercial war duty. Dual-engine certified? Sorry.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The e-volo multirotor movie has a nice white seemingly unloaded 2-fore heli frame with a DC patch panel, no rotor or tail, and instead a rack of smaller props. It goes up in a test hangar/messe and doesn't self-invert or evert...at some point reminds of the incidental score from that drone repairman flick where Jony Ive designed the humankind-wrecking drones' looks, and sounds like a lot of fans; performance is not up front in this production (though batteries were surely lofted.) They should at least cut the reel to appear to have a white cat onboard?&lt;/p&gt;&#xA;" OwnerUserId="3818" LastActivityDate="2014-10-08T01:40:50.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="8986" PostTypeId="1" CreationDate="2014-10-08T05:28:03.917" Score="103" ViewCount="40158" Body="&lt;p&gt;Yes, this is a question from the movies. Assume that the plane is in flight and in perfect mechanical conditions. However, all the pilots onboard are suddenly incapacitated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can a passenger without any previous flight experience realistically save the plane and take it to a safe landing only by remote radio help?&lt;/p&gt;&#xA;" OwnerUserId="3672" LastEditorUserId="22550" LastEditDate="2018-12-14T23:01:51.563" LastActivityDate="2018-12-14T23:01:51.563" Title="Can a passenger realistically replace suddenly incapacitated pilots?" Tags="&lt;pilots&gt;&lt;passenger&gt;&lt;pilot-incapacitation&gt;" AnswerCount="13" CommentCount="19" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="8987" PostTypeId="2" ParentId="8986" CreationDate="2014-10-08T06:15:58.720" Score="75" Body="&lt;p&gt;I guess this is a secret dream of many of you here: You sit on a scheduled flight, and hear in the PA system: &quot;Both our pilots just passed out. Any volunteers to take over their duties?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Won't happen.&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think of what would happen next: Panic! The volunteers won't even make it to the cockpit. All cabin crew are focussed to keep the cabin calm, so this announcement will never be made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, one of the cabin crew will take over. That is part of their duties, actually, and some airlines even give them basic training so they have a fair chance when they are in contact with someone on the ground who can talk them through all steps.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit: Thanks to some commenters for pointing out that the question also includes GA traffic. Yes, I did not cover this. Generally, I think a passenger should have an easier time to take over, when he/she is sitting already in the right seat. He/she could watch the pilot before and has a full set of controls available. GA planes move much more slowly, so things happen at a slower pace and much less kinetic energy is involved if the touchdown is not perfect. Much depends on the constitution of the new pilot: Some people will simply panic and not be able to follow even the best remote help. But if they keep their cool, a good landing (meaning one you can walk away from) should be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had been in the right seat of a Lancair once and the pilot turned the plane over to me on final. The Lancair was so sensitive in pitch that I porpoised the aircraft - I first had to get adjusted. So even a pilot in a new type might not be able to land it immediately when he gets to fly it first time on short final!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-08T13:02:10.297" LastActivityDate="2014-10-08T13:02:10.297" CommentCount="34" ContentLicense="CC BY-SA 3.0" />
  <row Id="8988" PostTypeId="2" ParentId="8980" CreationDate="2014-10-08T07:58:05.567" Score="20" Body="&lt;p&gt;It certainly seems so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stealth aircraft are not &lt;em&gt;invisible&lt;/em&gt; to radar, only &lt;em&gt;less&lt;/em&gt; visible.  Under certain conditions the adversary will be able to get a radar lock:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At close distance&lt;/li&gt;&#xA;&lt;li&gt;With very high (focused) radar energy&lt;/li&gt;&#xA;&lt;li&gt;At certain angles of incidence&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Given these risks and the low weight of chaff, it wouldn't be be wise to not carry it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One source that claims the F-22 carries chaff: &lt;a href=&quot;http://science.howstuffworks.com/f-22-raptor8.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://science.howstuffworks.com/f-22-raptor8.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It releases &lt;strong&gt;flares&lt;/strong&gt; to confuse heat seekers and sends out &lt;strong&gt;chaff&lt;/strong&gt;, small pieces of reflective material, to disperse radar waves and confuse a radar-guided missile's tracking system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's even been used in the field, &lt;a href=&quot;https://www.washingtonpost.com/news/checkpoint/wp/2017/12/14/u-s-f-22s-fired-warning-flares-at-russian-planes-in-close-call-over-syria-pentagon-says/?utm_term=.3854b6c87a9e&quot; rel=&quot;nofollow noreferrer&quot;&gt;according to The Washington Post&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the [F-22s] shot flares and even chaff — clouds of metal meant to confuse radar systems but possibly used in this case as an additional visual warning.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="3151" LastEditDate="2017-12-22T16:37:20.883" LastActivityDate="2017-12-22T16:37:20.883" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8989" PostTypeId="2" ParentId="8986" CreationDate="2014-10-08T08:05:30.913" Score="61" Body="&lt;p&gt;Actually, this theory has been tested a few times in simulators and small aircrafts with little twists here and there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Take a look at this video:&lt;/strong&gt; &lt;a href=&quot;https://www.youtube.com/watch?v=LkOT3fbc1O4&quot;&gt;Amateur Trying to Land Airbus A320 from 2500 Altitude&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you can get to the controls:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may be possible, but I believe it is very unlikely to be successful. Based on all the videos I see online, people attempting to do it, fail a few times before they get it right. In the video &lt;em&gt;(linked above)&lt;/em&gt;, she crashed like five times before she managed it like shown in the video. Also, If you don't have autoland and sit in a big, heavy aircraft, the chances are very slim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I really can't say yes or no to this question. There are a ton of factors that counts to decide whenever this is possible or not. For example weather, type of aircraft, weight of aircraft, self-taught experience with the airplane, and a big load of confidence (especially if you have never seen a cockpit before). If the plane has ILS systems with full Auto-landing options, I'd say your chances are better assuming you know how to program it, or get instructions from air-traffic controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So all in all, you are likely to survive, but the plane may be badly damaged on touchdown.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Here are a few more interesting (not directly relevant) examples:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=OcrpR1YI1qc&quot;&gt;A man learns how to fly a real 737 in just one month.&lt;/a&gt; (My personal favorite)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=htg0VKt3j_w&quot;&gt;A private pilot takes over the controls of a Embraer 190 in mid-flight&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=jJT_CACIZqs&quot;&gt;A pilot with no real-life flying hours (only flight simulation hours) takes the controls of a real Cessna 172.&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="693" LastEditorUserId="65" LastEditDate="2014-12-03T18:26:19.063" LastActivityDate="2014-12-03T18:26:19.063" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="8991" PostTypeId="1" AcceptedAnswerId="9076" CreationDate="2014-10-08T12:03:50.733" Score="9" ViewCount="13692" Body="&lt;p&gt;I wonder how an commercial aircraft used to transport passengers is used on a typical day. I imagine several scenarii, but I cannot figure out if they are right:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;take off in the morning from the company's hub to an airport and then get back and begin again all day long, possibly with a changing the crew when turning at the company's hub&lt;/li&gt;&#xA;&lt;li&gt;from the company's hub, begin the day with a round trip to an airport A, then performing a round trip to from the hub to an airport B, and continuing with other airport until the end of the day&lt;/li&gt;&#xA;&lt;li&gt;a triangular shape: a one-way leg from the hub to an airport A, then another leg from the airport A to an airport B, and then another from B to the hub, and continuing until the end of the day. A derivative could be the same with more airports (hub --&gt; A --&gt; B --&gt; C --&gt; D --&gt; hub)&lt;/li&gt;&#xA;&lt;li&gt;a long multi-leg route in one direction and then back (eg. A --&gt; B --&gt; C --&gt; D --&gt; C --&gt; B --&gt; A)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2014-10-09T11:48:41.220" LastActivityDate="2014-10-12T14:29:21.987" Title="On how many routes an aircraft is used on a typical day?" Tags="&lt;airline-operations&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8992" PostTypeId="2" ParentId="8991" CreationDate="2014-10-08T12:32:36.177" Score="5" Body="&lt;p&gt;Depends, sometimes the schedule is tight so the aircraft do several trips without going to the hub. Some companies have designated aircrafts to one specific route (ex: A &gt; B &gt; A &gt; B &gt; A &gt; B and so on). In my experience everything depends on company schedule, aircraft availability, crews avaliable, aircraft inspections, airport restrictions, etc&lt;/p&gt;&#xA;" OwnerUserId="3817" LastActivityDate="2014-10-08T12:32:36.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8993" PostTypeId="2" ParentId="8991" CreationDate="2014-10-08T13:51:54.777" Score="5" Body="&lt;p&gt;That'd depend highly on the aircraft and route network.&lt;br/&gt;&#xA;A 737 doing one hour hops might make 10-15 such in a day's job, a 747 flying a 14 hour leg won't make it back home the same day.&lt;br/&gt;&#xA;And then there's anything in between.&lt;br/&gt;&#xA;And whether that 737 flies the same legs over and over again or visits multiple destinations depends entirely on the owner's scheduling department, there's no hard and set rule (maybe it's a -900 which is needed between Amsterdam and London during morning rush traffic, then flies a longer flight to Tel Aviv in the afternoon, and in the evening hops to Berlin and then to Paris before being towed to a hangar for overnight cleaning and minor maintenance).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-10-08T13:51:54.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8994" PostTypeId="5" CreationDate="2014-10-08T13:55:47.597" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-08T13:55:47.597" LastActivityDate="2014-10-08T13:55:47.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="8995" PostTypeId="4" CreationDate="2014-10-08T13:55:47.597" Score="0" Body="Questions dealing with regulations promulgated by India's Directorate General of Civil Aviation (DGCA)." OwnerUserId="19" LastEditorUserId="22726" LastEditDate="2019-10-24T03:17:18.377" LastActivityDate="2019-10-24T03:17:18.377" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="8996" PostTypeId="2" ParentId="8339" CreationDate="2014-10-08T16:13:29.323" Score="5" Body="&lt;p&gt;Jet engine transportation is a highly specialized task, the primary method is ground transportation via truck and trailer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is important that the transport company uses fully air-ride trailers and advanced load securement techniques to ensure zero stress on sensitive engine components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Peter Kämpf - While you are correct that some engines can fit inside of an aircraft for transport, the cost for this service is enormous when you compare it to a truck and trailer. Also larger engines such as the Trent 1000 (Fits on a 787 Dreamliner) will not fit inside of an air cargo carrier.&lt;/p&gt;&#xA;" OwnerUserId="3824" LastEditorUserId="1467" LastEditDate="2014-10-16T06:52:05.430" LastActivityDate="2014-10-16T06:52:05.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="8997" PostTypeId="2" ParentId="8986" CreationDate="2014-10-08T17:02:23.110" Score="52" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=tJ8K-hOcRHk&quot;&gt;Mythbusters tested this&lt;/a&gt;. They each tried once without guidance and failed miserably.  Then they had a veteran ATC assist them and they both landed successfully.  So the experiment was tainted just a bit since they got a practice run, but it doesn't seem like they really learned anything from that practice run (they didn't even know what all of the controls did, and IIRC one of them didn't even manage to get the landing gear out), so for all intents and purposes they were doing it for the first time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More importantly, after having their fun in the simulator, the show notes that all modern commercial jets are equipped with autoland, so all the passenger would need to do is program it, with instructions from ATC.  ATC may even be able to program it remotely on current aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the case of a small aircraft without such fancy equipment, the answer is still yes.  There's a saying in aviation: &quot;A good landing is one where you can walk away.  A great landing is one where you can use the plane again.&quot;  If you lower your expectations about what a &quot;landing&quot; entails, it's not too hard to land a small prop plane.  They can travel surprisingly slowly and don't require much runway length (so you could burn half the runway just trying to get lined up and level and still be fine).  Depending on the conditions, a better option might be to leave the landing gear up and skid it into an empty field.  With ATC guidance, this is really not too hard.&lt;/p&gt;&#xA;" OwnerUserId="3826" LastEditorUserId="5537" LastEditDate="2015-09-04T09:13:17.867" LastActivityDate="2015-09-04T09:13:17.867" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="8998" PostTypeId="2" ParentId="8986" CreationDate="2014-10-08T18:03:18.337" Score="20" Body="&lt;p&gt;For a completely untrained person it would be hard and would take hours of practice, so a lot would depend how much fuel the plane had.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory it is possible, as long as you have a long runway, because you can land it on a really shallow glide slope, which takes a lot of potential problems out the equation. As long as the guy has it lined up right, configured correctly and is going the right speed, the plane will more or less land itself. It's just a question of how many times he has to go around before he lines it up right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't forget the &lt;a href=&quot;https://en.wikipedia.org/wiki/Colton_Harris-Moore&quot; rel=&quot;noreferrer&quot;&gt;Barefoot Bandit&lt;/a&gt; who stole a bunch of planes and &quot;landed&quot; them multiple times successfully using only the information in the operator's manual. Not pretty landings, but, hey, he landed and walked away each time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;------------------- ** FOLLOW UP **&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I asked a senior pilot/instructor/examiner at American about this. He said the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) Stewards are not trained to take over in the event of such an emergency&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) On many flights there are pilots flying in a jump seat or making a transit and these could take over if they are present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) In the unlikely event that the crew was incapacitated and there was no other regular pilot on board, the flight attendants would ask among the passengers if anyone has a pilot's license. In this situation the disadvantages of &quot;inducing panic&quot; would be irrelevant compared to the value of having an experienced pilot flying the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(4) If an untrained person had to fly the plane, it could probably be done successfully in most cases using the automatic features of modern commercial carriers.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-10T22:52:42.680" LastActivityDate="2015-10-10T22:52:42.680" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="8999" PostTypeId="2" ParentId="8986" CreationDate="2014-10-08T19:20:44.127" Score="9" Body="&lt;p&gt;Somebody calm and with radio communication could land an airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They would need to be able to use the Mode Control Panel, possibly the &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_management_system&quot; rel=&quot;nofollow&quot;&gt;FMS&lt;/a&gt;, perform an &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow&quot;&gt;ILS&lt;/a&gt; capture (likely controlled entirely by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_terminal_arrival_route&quot; rel=&quot;nofollow&quot;&gt;STAR&lt;/a&gt; in the FMS), autobrake settings and be able to control flap settings and gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If in the cruise, the flight management computer (FMC) could fly from &lt;a href=&quot;https://en.wikipedia.org/wiki/Top_of_descent&quot; rel=&quot;nofollow&quot;&gt;TOD&lt;/a&gt; down to a long final with ILS capture, flap retraction, drop the gear and maximum autobrakes using &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_level&quot; rel=&quot;nofollow&quot;&gt;flight level change&lt;/a&gt; (FLCH) and speed control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this could be explained over the radio.&lt;/p&gt;&#xA;" OwnerUserId="3828" LastEditorUserId="753" LastEditDate="2015-09-04T09:03:32.440" LastActivityDate="2015-09-04T09:03:32.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9000" PostTypeId="2" ParentId="8479" CreationDate="2014-10-08T20:01:39.730" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.dji.com/product/phantom-2-vision&quot; rel=&quot;nofollow&quot;&gt;Phantom 2 Vision&lt;/a&gt; are VERY high-quality drones, perfectly suited for what you are looking for, and I believe they come with their own imaging equipment.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="65" LastEditDate="2015-03-04T19:38:33.767" LastActivityDate="2015-03-04T19:38:33.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9001" PostTypeId="1" AcceptedAnswerId="9003" CreationDate="2014-10-08T20:09:28.587" Score="13" ViewCount="6919" Body="&lt;p&gt;Do tanker aircraft, (such as the KC-135, KC-10, S-3B, etc), distribute fuel from their own fuel tanks, or is it strictly from a separate cargo tank?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, some cargo tanks are going to be involved, as an aircraft carrying only the fuel in it's wing tanks isn't going to be a whole lot, and some of these aircraft are known to fuel some very thirsty birds, such as B-52's, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sub question: What proportion volume of the aircraft's fuselage is taken up by the addidional fuel. Do they just pack it as full as they can with fuel? Seems like this would very quickly add to weight, and you would struggle getting such a fuel laden ass bird off the ground.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2015-07-08T20:25:37.387" Title="Do tanker aircraft distribute their own fuel?" Tags="&lt;military&gt;&lt;fuel-tanks&gt;&lt;refueling&gt;&lt;tanker&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9003" PostTypeId="2" ParentId="9001" CreationDate="2014-10-08T21:07:37.490" Score="15" Body="&lt;p&gt;Both the KC-135 and KC-10 can burn the fuel it carries on board for refueling (the notable exception was the KC-135Q, which carried separate tanks of JP-7 for the SR-71 Blackbird).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Yn8LZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both indeed do have significant fuselage tanks - the KC-10 is notable for being 'dual-mission' capable, meaning it can carry both fuel and cargo, and the KC-10 is also air-refuelable (so a KC-135 can offload extra gas into a KC-10 when their &lt;a href=&quot;https://aviation.stackexchange.com/questions/8784/do-military-pilots-have-flight-rest-hours-regulation/8789&quot;&gt;crew rest&lt;/a&gt; is up, allowing the KC-10 to stay on station and refuel other planes longer). The maximum fuel load of a KC-10 is 356,000 pounds. This is over 7 full loads of gas for a B-52 (B-52G and H could carry 308,000lbs of fuel, so 365,000 capacity of KC-10 would potentially fully fuel a B-52 one time, with enough fuel left to get the KC-10 home. Of course the B-52 would never be completely empty in the air so the KC-10 would not need to offload the full 308,000lbs), or 30 full loads for an F-16 with external tanks, and the maximum fuel load of a KC-135 is 200,000 pounds, or over 4 full loads of gas for a B-52.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how much of the fuselage is taken up by fuel tanks, you can look at cutaways of the &lt;a href=&quot;http://sobchak.files.wordpress.com/2009/09/kc135cutaway.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;KC-135&lt;/a&gt; and &lt;a href=&quot;http://aviadejavu.ru/Images6/MM/MM-128/0305-01-2-6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;KC-10&lt;/a&gt; &lt;em&gt;(unfortunately the captions for the KC-10 are in a foreign language, as I could not find a high-enough resolution one in English)&lt;/em&gt;. In both cases, the fuel tanks are in the lower half of the fuselage - the reason the KC-10 has a cargo mission as well is because it is a larger aircraft and has a much higher gross weight. The KC-135's cargo space is much smaller, and as such is not used for transporting large items. &lt;a href=&quot;http://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=11&amp;amp;ved=0CEoQFjAK&amp;amp;url=http%3A%2F%2Fwww.dtic.mil%2Fcgi-bin%2FGetTRDoc%3FAD%3DADA408235&amp;amp;ei=zKc1VMSVL9L4yQTj_YFw&amp;amp;usg=AFQjCNEs8khinFfjVrV7wRyofnY2e2uh-g&amp;amp;sig2=yof9x0-eFtwBJMXZWVy5dg&amp;amp;bvm=bv.76943099,d.aWw&quot; rel=&quot;nofollow noreferrer&quot;&gt;This technical document&lt;/a&gt; for the KC-10 also gives volume of each tank (called &lt;em&gt;Fuel Cells&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Forward Fuselage - 8,250 gallons in 3 sections, 6' deep&lt;/li&gt;&#xA;&lt;li&gt;Aft Fuselage - 9,870 gallons in 4 sections, 6' deep&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You are correct that it is a struggle getting them airborne when fully loaded - several of the KC-135 pilots I have talked to have taken until the very end of 10,000 foot plus runways to get airborne, and one of the KC-10 pilots I know said they would occasionally take off with less than a full load then take on fuel from a KC-135 to make it easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Page 3-45 of &lt;a href=&quot;http://books.google.com/books?id=GDPlAwAAQBAJ&amp;amp;pg=SA3-PA10&amp;amp;lpg=SA3-PA10&amp;amp;dq=kc%2010%20takeoff%20distance&amp;amp;source=bl&amp;amp;ots=xqCs2De8Bv&amp;amp;sig=UxBvOlJuk3B7WHxOQwaawP6ccWU&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=c6o1VJ65JoixyATV8oHADw&amp;amp;ved=0CEsQ6AEwBQ#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; technical manual has a chart for calculating minimum runway for a particular speed - for example, a sea level takeoff at 30 degrees (Celsius) at Max takeoff weight would require about a 13,500 foot runway.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-08T20:25:37.387" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9004" PostTypeId="2" ParentId="7460" CreationDate="2014-10-08T22:03:47.767" Score="3" Body="&lt;p&gt;No need to run the fuel pump as @Skip Miller says.  (though it may say that in the Saratoga manual)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have done the following with success for hot starts on a IO-320, IO-360, and IO-540.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Throttle Full Open. (Push in or forward) &lt;/li&gt;&#xA;&lt;li&gt;Mixture Full Close. (Pull out or back)&lt;/li&gt;&#xA;&lt;li&gt;Crank engine.&lt;/li&gt;&#xA;&lt;li&gt;Once it starts firing, put the mixture back in and pull the throttle back to idle.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Happy engine starts!&lt;/p&gt;&#xA;" OwnerUserId="150" LastActivityDate="2014-10-08T22:03:47.767" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9005" PostTypeId="1" AcceptedAnswerId="9012" CreationDate="2014-10-09T00:36:14.313" Score="43" ViewCount="15971" Body="&lt;p&gt;Related question: &lt;a href=&quot;https://aviation.stackexchange.com/q/3015/3170&quot;&gt;do planes have keys?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I happen to spot a fine-looking plane at my local airport and decide the owner probably wouldn't mind if I borrowed her for a little while - what stops me from stealing this plane? On commercial jets, the cockpit door is locked, but as I understand smaller planes don't have cockpit doors. The linked question suggests that single-engine planes have ignition keys, but twin-engine planes don't. Are the outer doors (cabin doors) locked? What else restricts me from walking up, climbing in, and flying away? (Other than the fact that I don't have the least clue how to fly a plane.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is about all types of planes.)&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-07-03T22:10:32.320" Title="What stops planes from being stolen?" Tags="&lt;aircraft-design&gt;&lt;security&gt;" AnswerCount="10" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9006" PostTypeId="1" AcceptedAnswerId="9015" CreationDate="2014-10-09T01:01:45.733" Score="11" ViewCount="28278" Body="&lt;p&gt;How do I determine the VFR pattern altitude at an airport? Can I find it on a sectional?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="572" LastEditDate="2015-02-19T09:00:00.823" LastActivityDate="2017-04-30T16:57:10.600" Title="How do I determine the VFR pattern altitude at an airport?" Tags="&lt;airport&gt;&lt;aeronautical-charts&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9007" PostTypeId="2" ParentId="9006" CreationDate="2014-10-09T02:09:42.607" Score="3" Body="&lt;p&gt;No, it's not on a sectional. The Traffic Pattern Altitude (TPA) can be found in your A/FD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: I just double-checked and it's not on all airports in the A/FD. I would assume that if it's not listed it's 1000' AGL, but not sure why it's listed on some and not others. When it is there it'll be on the 2nd line after fuel. It'll look something like this: &lt;code&gt;TPA-1072(1000)&lt;/code&gt;&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="755" LastEditDate="2016-02-11T20:08:47.937" LastActivityDate="2016-02-11T20:08:47.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9008" PostTypeId="2" ParentId="9005" CreationDate="2014-10-09T02:35:22.253" Score="15" Body="&lt;p&gt;Don't know about larger jets, but GA planes do have keys, which enables the engine to cycle by ungrounding the circuit that allows a charge to pass from the magnetos to the spark plug. That said, they are usually very low-tech. I don't think engine compartments are ever locked and you could do a small bit of rewiring to bypass the ignition switch pretty easily then hand-crank the prop to start it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To combat the low-tech ignition, many planes have lojack installed &amp;amp; are kept in locked hangars. Also, most airports have security cameras and ATC records radar, so a stolen plane would be pretty easy to track down.&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="609" LastEditDate="2015-04-09T14:29:44.350" LastActivityDate="2015-04-09T14:29:44.350" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9009" PostTypeId="1" CreationDate="2014-10-09T02:52:59.573" Score="4" ViewCount="200" Body="&lt;p&gt;I currently own a 1/4 share of an Archer, but due to relocating I have put it up for sale and was planning to find another partnership once its sold. It's been on the market for about 3 months and have not had many people contact me with interest (no one serious). The other option I am debating is to buy up the other 3 shares and make the plane available for leaseback down in my new area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone have any feedback if leaseback is a good option? If I can get 80hrs/month (which is what the FBO owner says he's getting on each of his 172s), then I'd earn enough to cover the loan for buying the 3/4 shares, but I'm very concerned of hidden pitfalls. I've seen the condition of most rental planes &amp;amp; I'd be appalled if my Archer ever looked like those. Does anyone have any advice/suggestions?&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="1696" LastEditDate="2015-10-07T14:56:42.543" LastActivityDate="2015-10-07T14:56:42.543" Title="Sell 1/4 share or buy 3/4 share and leaseback?" Tags="&lt;general-aviation&gt;&lt;aircraft-ownership&gt;" AnswerCount="0" CommentCount="1" FavoriteCount="1" ClosedDate="2014-10-12T17:09:50.887" ContentLicense="CC BY-SA 3.0" />
  <row Id="9010" PostTypeId="2" ParentId="8986" CreationDate="2014-10-09T06:18:52.453" Score="3" Body="&lt;p&gt;When I first read the question, I thought, &quot;sure, if you're an ex-USAF pilot like I am, not a problem&quot; (every time I fly on an airline, that fantasy occurs to me lol). But then I saw that the question was caveated with &quot;no previous flight experience&quot;. Oh well :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the odds would be 50-50 at best whether someone with absolutely no flight experience could land a modern jet airliner without crashing, even with the absolute best radio instructions possible. Maybe even worse odds than that.&lt;/p&gt;&#xA;" OwnerUserId="3833" LastActivityDate="2014-10-09T06:18:52.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9011" PostTypeId="2" ParentId="8986" CreationDate="2014-10-09T06:39:24.313" Score="4" Body="&lt;p&gt;An interesting question. I am fairly certain that a modern figther jet would be a lot easier to land than a typical airliner, due to not having quite as much automation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I worked with a simulator for a fighter jet and at least one pilot thought we (the IT guys working on the sim) would be able to land the real plane if it came to that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, when we had random clients try landing the sim when flying it for the first time, it almost always worked when someone talked them down, standing by their side, using ILS. You don't have that luxury in a real plane: nobody can point to the controls for example. If people would have tried on their own, I think fewer than 1 in 5 would have made it. I mean with no help even from the radio, hence no glide-slope to guide the landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You just need to have a feeling for the touchdown, and the only way to get that is practice. Which in this case there is none! Jet airliners are also a lot less forgiving than a smaller plane due to all that inertia/weight, so to be honest I think a controlled crash is the likely best outcome.&lt;/p&gt;&#xA;" OwnerUserId="3832" LastEditorUserId="753" LastEditDate="2015-09-04T09:09:30.573" LastActivityDate="2015-09-04T09:09:30.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9012" PostTypeId="2" ParentId="9005" CreationDate="2014-10-09T06:45:12.283" Score="39" Body="&lt;p&gt;There are a several theft-deterrent mechanisms in place.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On small airplanes, most commonly, the &lt;em&gt;door&lt;/em&gt; to the airplane itself is usually&#xA;locked with a key. (Notice the key cylinder in this picture below the silver door handle:&lt;br/&gt;&lt;img src=&quot;https://i.stack.imgur.com/jYHDv.jpg&quot; alt=&quot;Cessna door&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;Prop locks:&lt;br/&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Hhal.jpg&quot; alt=&quot;There could be a prop lock (like a heavy-duty bike lock)&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;Throttle locks:&lt;br/&gt;&lt;img src=&quot;https://i.stack.imgur.com/ABOVK.jpg&quot; alt=&quot;There could be a Throttle Lock&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;A lot of airplanes do have an ignition key which you turn to engage the starter.  Of course, as &lt;a href=&quot;https://aviation.stackexchange.com/a/9008/65&quot;&gt;jaytre mentioned&lt;/a&gt;, this can be circumvented by hand-propping (which is a very dangerous endeavor for unskilled people who haven't done it before)&lt;/li&gt;&#xA;&lt;li&gt;You would have to know how to operate the basic systems of the airplane as well as how to fly.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aopa.org/Advocacy/Security-and-Borders/Airport-Watch-Security.aspx&quot; rel=&quot;noreferrer&quot;&gt;AOPA's Airport Watch Program&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Fences and other physical security measures around airports.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="132" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-10-09T21:07:53.337" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9013" PostTypeId="2" ParentId="8702" CreationDate="2014-10-09T07:04:06.213" Score="7" Body="&lt;p&gt;Helicopters also have a stat you might have seen called &lt;em&gt;In Ground Effect (IGE)&lt;/em&gt; and &lt;em&gt;Out of Ground Effect (OGE)&lt;/em&gt; Hover altitudes.  This is the maximum altitude (MSL) the helicopter can hover at when it is in or out of ground effect.  Essentially, when IGE, a helicopter can hover at higher Mean Sea Level (MSL) altitudes because they get a little help from the proximity of the ground, which reduces the rotor tip vortices (reduces the drag on the rotor). &lt;a href=&quot;http://www.copters.com/aero/ground_effect.html&quot;&gt;This site has some good info on ground effect as it relates to helicopters.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2014-10-09T07:04:06.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9014" PostTypeId="1" CreationDate="2014-10-09T07:08:24.117" Score="25" ViewCount="6671" Body="&lt;p&gt;I was talking to a Sheriff's Department helicopter pilot and he was saying they fly around at night with night vision goggles.  I know the military does too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some of the considerations that pilots flying with night vision goggles have to deal with when learning to fly with them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long does it take for someone to be certified/trained to fly with night vision goggles?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the most difficult part about it? Could civilians do it if they owned the gear?&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2018-02-18T00:08:18.630" Title="How hard is it to fly with night vision goggles?" Tags="&lt;military&gt;&lt;pilot-technique&gt;&lt;night-flying&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9015" PostTypeId="2" ParentId="9006" CreationDate="2014-10-09T07:26:15.157" Score="16" Body="&lt;p&gt;In April 2013, the FAA's Charting Group &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media/RDs/13-01-262-AFD-depiction-traffic-patterns-alt.pdf&quot; rel=&quot;noreferrer&quot;&gt;met to discuss this question&lt;/a&gt;.  The standard pattern used to be 800 ft AGL, and the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/&quot; rel=&quot;noreferrer&quot;&gt;Chart Supplement&lt;/a&gt; (formerly called Airport/Facility Directory or A/FD) was inconsistent in listing them.  Ultimately they decided: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Chris Criswell, AJV-22, reported that, per ACF recommendation, all traffic pattern altitudes, standard and non-standard, will be added into NASR (the AFD) for all airports. This will be a day forward implementation beginning in July 2014. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some other places the TPA is recommended to be 1000 feet AGL:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC90-66A.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory_Circular AC90-66A&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. It is recommended that airplanes observe a 1000 foot above ground&#xA;  level (AGL) traffic pattern altitude. Large and turbine powered&#xA;  airplanes should enter the traffic pattern at an altitude of 1,500&#xA;  feet AGL or 500 feet above the established pattern altitude. A pilot&#xA;  may vary the size of the traffic pattern depending on the aircraft's&#xA;  performance characteristics.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Chart Supplement (A/FD) will typically list the Traffic Pattern Altitude (TPA) if it is non-standard (not 1000 ft/1500 ft AGL)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA's &lt;em&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airplane Flying Handbook&lt;/a&gt;&lt;/em&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The traffic pattern altitude is usually 1,000 feet above the elevation of the airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now the Chart Supplement (A/FD) will be the definitive guide!&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="132" LastEditDate="2016-09-13T02:58:07.797" LastActivityDate="2016-09-13T02:58:07.797" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9016" PostTypeId="2" ParentId="9005" CreationDate="2014-10-09T08:59:56.187" Score="10" Body="&lt;p&gt;Given the very lightweight construction of GA aircraft, any physical security to the cabin will do nothing more than make the owner feel better about it. Propeller locks like the one in the other answer's picture are highly effective - you won't be going anywhere with it on, and it makes an awful lot of noise cutting it off. mind you don't cut the prop blade in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial jet cockpits aren't locked to prevent someone flying away with it, they are locked to prevent hijacking. This is new since 2001 - before that the cockpit door was no stronger than the one on the toilet.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-09T08:59:56.187" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9017" PostTypeId="1" AcceptedAnswerId="9022" CreationDate="2014-10-09T10:21:14.483" Score="15" ViewCount="7172" Body="&lt;p&gt;Many very large airplanes have specific information of their empty weight. For instance the weight of an empty, regular 747-400 is 393,263 lb (178,756 kg) according to Wikipedia. The Concorde is 78,700 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is the weight of these airplanes measured so precisely (note that in the 747-400 example is precise to the unit's place!). Is the sum of the weights of all the parts used? Also, is Zero Fuel Weight (ZFW) the same as empty weight?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="504" LastEditDate="2014-10-10T10:40:24.117" LastActivityDate="2014-10-10T10:40:24.117" Title="How is the weight of an airplane measured?" Tags="&lt;aircraft-design&gt;&lt;weight-and-balance&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9018" PostTypeId="2" ParentId="9005" CreationDate="2014-10-09T11:10:29.243" Score="36" Body="&lt;p&gt;The difficulty of first hiding and then legalizing the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the thief got into the plane. But what's he going to do with it? A car can be repainted in any remote garage and nobody will notice and registration is just a piece of paper relatively easy to fake. But aircraft can't be landed just anywhere. So police has manageable list of places to check for the plane and by looking at ATC recordings they can help further narrow down the search. Even if the plane flies through uncontrolled airspace only it may come up on primary radar now and then. Or get noticed by some witnesses if it flew very low to avoid that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then the thieves need to get a new registration for it to be able to use it or sell it. So they have to create a fake registration and re-register the plane. But for planes this is much more thorough process than for cars, so the risk the civil aviation authority of given state will notice some discrepancy between the fake papers and various databases that will inevitably exist is again pretty high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So even if the thief would be able to get into the plane, they would have hard time avoiding being caught later, taking away the motivation to try stealing a plane in the first place.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-10-09T11:10:29.243" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9019" PostTypeId="2" ParentId="8986" CreationDate="2014-10-09T11:32:03.783" Score="2" Body="&lt;p&gt;I would suggest to use a mobile phone to call a police - that much most of people can easily do. The police should tell the phone number to contact the airport. From there, it may be possible to receive professional instructions how use the radio on the plane, and further professional instructions that I believe should at least reduce the number of casualties. Even assuming the most hopeless scenario, even crashing in remote area away from houses is already something. Maybe it is possible to do something better in comparison to that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know, maybe at least in some cases an airport may even tell the code to unlock the door. The airport would see that legitimate pilots are no longer responding to the radio calls, the plane is not following the planned path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mobile phones &lt;a href=&quot;http://www.911myths.com/html/mobiles_at_altitude.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;generally work&lt;/a&gt; from the airplane, while it may be better slow down and descend below cruising altitude. This is probably easier than to land. Also, as noted by @DJZorrow, it may be built - in passenger phones on a plane that are more likely to work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, with 200+ seats in the airliner, there is a non-zero possibility that an ATP that is (or has been) rated for the type is flying as a passenger. Because of that, I think, some attempt to recruit able passengers should be made rather than just leaving controls unattended.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2018-11-02T07:52:58.633" LastActivityDate="2018-11-02T07:52:58.633" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="9020" PostTypeId="2" ParentId="9017" CreationDate="2014-10-09T11:53:39.850" Score="10" Body="&lt;p&gt;You get yourself some load cells, put them under the gear axles / lift points etc. and jack it off the ground. The attached computer will tell you the total mass, center of gravity etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several companies produce &lt;a href=&quot;https://www.google.com/#q=aircraft+weigh+scale&quot;&gt;aircraft weighing scales&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1032" LastEditDate="2014-10-09T17:38:30.167" LastActivityDate="2014-10-09T17:38:30.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9021" PostTypeId="2" ParentId="9017" CreationDate="2014-10-09T14:19:44.593" Score="14" Body="&lt;p&gt;Addressing the ZFW question, zero fuel weight is not the same as empty weight.  Empty weight is the weight of the airplane without any people, bags, cargo or fuel on board.  Zero fuel weight is the weight of the airplane plus people, bags and cargo, but does not include fuel.  The ZFW is important because there is usually a limitation of maximum ZFW. For example, once you hit max ZFW you can no longer add people or cargo to the airplane, even if you would stay under max gross weight including fuel.  The only weight you can add to the airplane above the max ZFW is fuel.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-10-09T18:37:24.800" LastActivityDate="2014-10-09T18:37:24.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9022" PostTypeId="2" ParentId="9017" CreationDate="2014-10-09T15:24:08.467" Score="16" Body="&lt;p&gt;The empty weight of airplanes can only be given to single-pound precision for one specific airplane. Minute differences in metal sheet thickness, equipment and paint will make sure that there is a difference of many pounds between airplanes of the same type and furnishing. Add to this the difference in seating, galleys and instrumentation between airplanes of the same type which are operated by different airlines, and a precise number as in your question becomes almost meaningless. A better way would be to give a range in which most airplanes will fall, or to round the number like the Concorde weight of your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weighing is quite straightforward: All tires of the landing gear are placed on scales and the weights are summed up. If the attitude of the airplane does not change, the weight on the tires can even be measured consecutively, so only one scale is needed. Small floatplanes can be suspended from a crane with a scale in the line holding the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://en.wikipedia.org/wiki/Ernst_Heinkel&quot;&gt;Ernst Heinkel&lt;/a&gt;'s biography he remembers an aircraft deal with the Soviet Union in the late 1920s. He had to deliver five floatplanes of a specified weight, and the Russian approval inspectors insisted on all planes having the exact same weight. Of course the planes were not identically heavy, but his advantage was that the scale in his factory was indicating the weight by printing it on cards. So the evening before the inspectors came, he let one aircraft be weighed five times, put the cards back into the machine and had the printing mechanism disabled. The next day he closed the business successfully with his very happy Russian guests.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-09T15:24:08.467" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9024" PostTypeId="2" ParentId="8986" CreationDate="2014-10-09T17:58:12.697" Score="0" Body="&lt;p&gt;I'm not an expert on this myself, however a former colleague of mine had to do with optimizing the ergonomics of the workplace of German national flight control and they told him that today, the autopilot can fully control an aircraft, including take-off and landing. So all you need to do is basically dial in the coordinates of the airport. And this can be explained over radio. So in case you can operate the radio, you'd probably have quite a good chance of getting that thing down. After that, you could basically get back to your seat and wait until you're down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The people at flight control were actually pretty humorous and were kidding like: &quot;Why do we even need pilots if these things can fly on their own?&quot; - &quot;Psst! Not too loud! Actually we don't need pilots. ;-)&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course that's not true and in case a big aircraft were to come down with autopilot, it would definitely be a rough landing, they'd probably clear the entire airport just in case and the aircraft may even take a bit of damage, but in &gt; 95 % of all cases, all passengers would get down unharmed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least that's what I heard. Like I said I have no clue myself, so it may be complete bullsh*t. And of course it's gonna be a lot different for smaller machines (sports planes) which don't have this kind of equipment and will probably be a lot harder to successfully land.&lt;/p&gt;&#xA;" OwnerUserId="3841" LastActivityDate="2014-10-09T17:58:12.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9025" PostTypeId="2" ParentId="9014" CreationDate="2014-10-09T18:32:34.847" Score="12" Body="&lt;p&gt;Actually, typically, they will only use one goggle, over one eye. (In my experience.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having instruments should overcome most of the difficulties of flying with NVG's. Certainly better than no night vision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most difficult challenge is having no depth perception.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An EMS/MEDSTAR helicopter in my hometown crashed while flying with night vision goggles for that very reason; they flew into a power line I believe which they thought was farther away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Old post, but I thought I'd share a story that I didn't think about at the time that is relevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Had a friend who was in the army and told me about having to be the lead vehicle in a &lt;a href=&quot;http://en.wikipedia.org/wiki/Humvee&quot; rel=&quot;noreferrer&quot;&gt;HMMWV&lt;/a&gt; column at night in a combat zone (which means no headlights) and having to drive with a night vision goggle over one eye (which means no depth perception) on a road on the side of a cliff for several hours.  The road was only about a foot wider than the vehicle. Scary stuff.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="65" LastEditDate="2015-03-21T15:32:00.227" LastActivityDate="2015-03-21T15:32:00.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9026" PostTypeId="2" ParentId="9017" CreationDate="2014-10-09T18:42:18.263" Score="5" Body="&lt;p&gt;Be aware that if a small change is made to an aircraft, like adding or removing equipment, the airplane is typically not reweighed but it's empty weight is recalculated by adding or subtracting the weight change. Also, the empty weight c.g. is recalculated by adding or subtracting the moment change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I remember, there is also an requirement that aircraft be reweighed every so many years. I want to say every 3 years, but that may be wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the empty weight does not include pilots and cabin crew. The term BOW (Basic Operating Weight) is often used that does include standard weights for pilots and cabin crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air carriers, particularly freight operators, may employ more than one BOW to allow them to easily switch between configurations. For example, freighters sometimes carry fly-away-kits (FAK) of several hundred pounds. The kits are strapped down, but can be quickly removed if need be. The operator might choose to have two BOWs, one including the FAK and one without it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also the matter of using &quot;fleet weights&quot; rather than individual airplane weights, or at least there used to be.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-10-09T18:42:18.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9027" PostTypeId="1" AcceptedAnswerId="9030" CreationDate="2014-10-09T18:55:18.930" Score="26" ViewCount="10994" Body="&lt;p&gt;When an F-15 (or your favorite fighter aircraft) punches it's external tanks...&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Iylkr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...to engage in combat, (or when they are empty), what happens to them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Through my best reasoning skills and Newton's calculations, I have determined that they will fall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what happens when they hit the ground? Do they explode? Do they detonate at a certain height? Is this a problem? Are there regulations determining where/when pilots may pickle their tanks? Have there ever been any accidents? (E.g. houses/cows/grandmothers destroyed by falling fuel tanks?)&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="1696" LastEditDate="2018-04-27T19:30:31.737" LastActivityDate="2018-04-27T19:30:31.737" Title="What happens to jettisoned fuel tanks?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9028" PostTypeId="2" ParentId="9027" CreationDate="2014-10-09T19:07:12.103" Score="5" Body="&lt;p&gt;It's more likely that they don't ditch tanks just because they are empty, they are reusable and not cheap and may still have some dregs of fuel in them. Besides ecologists already hate the military no need to aggravate them further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tank dropped for another reason drop and drill itself into the ground and may or may not survive in one piece. An explosion is unlikely unless there is an ignition source to spark the explosion.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-09T19:07:12.103" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9029" PostTypeId="2" ParentId="8726" CreationDate="2014-10-09T20:11:56.860" Score="2" Body="&lt;p&gt;One example of 26VAC in aircraft is in old analog avionics (think DC10-era autopilot or navigation instruments), where it is used as a reference voltage for the signals transmitted using synchro. I think these days it is fairly uncommon.&lt;/p&gt;&#xA;" OwnerUserId="3843" LastActivityDate="2014-10-09T20:11:56.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9030" PostTypeId="2" ParentId="9027" CreationDate="2014-10-09T20:13:26.957" Score="32" Body="&lt;p&gt;They are called &lt;a href=&quot;http://en.wikipedia.org/wiki/Drop_tank&quot; rel=&quot;noreferrer&quot;&gt;drop tanks&lt;/a&gt;. When a drop tank is jettisoned, very likely it is &lt;strong&gt;not&lt;/strong&gt; retrieved and reused. This is also the case with (sadly, discontinued) Space Shuttle &lt;a href=&quot;http://en.wikipedia.org/wiki/Space_Shuttle_external_tank&quot; rel=&quot;noreferrer&quot;&gt;external tank&lt;/a&gt;. Those tanks were &lt;a href=&quot;https://space.stackexchange.com/q/3616/1344&quot;&gt;not reused either&lt;/a&gt;. I am not talking about the &lt;a href=&quot;http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster&quot; rel=&quot;noreferrer&quot;&gt;rocket boosters&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What happens to jettisoned fuel tanks?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on where they land. The tanks jettisoned in Vietnam have been used to make boats (more &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2612962/Ingenious-farmers-build-vital-river-boats-fuel-tanks-jettisoned-U-S-planes-Vietnam-War.html&quot; rel=&quot;noreferrer&quot;&gt;pictures here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is worth noting that these external &lt;a href=&quot;http://en.wikipedia.org/wiki/Drop_tank#Overview&quot; rel=&quot;noreferrer&quot;&gt;fuel tanks have disadvantage too&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A general rule is that only about half the capacity of a streamlined&#xA;  drop tank actually goes towards increasing the aircraft's overall&#xA;  range, the rest going to overcome the added drag and weight of the&#xA;  tank itself.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:58:55.350" LastActivityDate="2015-10-30T18:09:17.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9031" PostTypeId="1" AcceptedAnswerId="9033" CreationDate="2014-10-09T22:54:03.200" Score="35" ViewCount="5839" Body="&lt;p&gt;I saw this picture today in a &lt;a href=&quot;http://www.abc.net.au/news/2014-10-10/islamic-state-seizes-large-areas-of-syrian-town-despite-air-str/5803544&quot;&gt;news article&lt;/a&gt; about the current conflict in Iraq/Syria.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8gig4.png&quot; alt=&quot;Plane Silhouette&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The caption claims it is a US warplane, but I don't recognise the silhouette. Can someone identify this plane?&lt;/p&gt;&#xA;" OwnerUserId="3845" LastEditorUserId="15311" LastEditDate="2018-08-16T14:59:38.497" LastActivityDate="2018-08-16T15:31:52.557" Title="Can someone identify this warplane silhouette?" Tags="&lt;aircraft-identification&gt;&lt;bomber&gt;&lt;strategic-bomber&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9032" PostTypeId="2" ParentId="9031" CreationDate="2014-10-09T23:30:05.367" Score="10" Body="&lt;p&gt;Yep. That's a B-1B Lancer: &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot;&gt;B-1 on the Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm surprised to see it over Iraq, I thought they were using smaller attack aircraft, F-15E's for example. The B-1 is a substantial (and, I can report, extremely loud) bomber with a big load. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They US have been flying them since the mid-80's.&lt;/p&gt;&#xA;" OwnerUserId="3846" LastActivityDate="2014-10-09T23:30:05.367" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9033" PostTypeId="2" ParentId="9031" CreationDate="2014-10-10T00:28:17.957" Score="56" Body="&lt;p&gt;This is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;noreferrer&quot;&gt;B-1B Lancer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a 4 engine (afterburning engines mind you, very rare for a bomber) variable sweep wing bomber, designed during the Cold War to use its terrain-following radar to stay low and fast, weaving between the mountains of Russia to stay below radar to deliver nuclear warheads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It carries more bombs than the B-52 as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, it is a bomber built like a fighter. It is actually the only swing-wing aircraft in the entire US military right now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fun fact: The canards near the nose aren't for control. Because the aircraft is flown by autopilot using terrain-following radar (TFR), weaving into and out of mountains, autopilot makes many quick pitch adjustments. The canards are to cancel out sine waves in the structure of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can carry a whole lotta' bombs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;24 nuclear bombs, 48 JDAMs, 84 Mk82 bombs, or 48 AGM missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;100 were built, 66 remain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I leave with my current desktop background:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/u37Qk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="15311" LastEditDate="2018-08-16T15:31:52.557" LastActivityDate="2018-08-16T15:31:52.557" CommentCount="17" ContentLicense="CC BY-SA 4.0" />
  <row Id="9035" PostTypeId="2" ParentId="8986" CreationDate="2014-10-10T09:15:55.123" Score="14" Body="&lt;p&gt;OP is asking if it’s POSSIBLE, not if it’s likely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question YES it’s possible. Actually it would be fairly “easy,” if you were talking on the radio to someone from that airline, who knows the aircraft type, layout, and systems. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First you would need to be able to talk to a controller.&lt;/li&gt;&#xA;&lt;li&gt;In order to do this, you would need to know that you can’t just start talking into the microphone. When you do this and the aircraft has a interphone lock switch, you would likely hear your own voice, and so you would think the air traffic controller (ATC) would be able to hear you. This is false as you have to “toggle” the switch. My aircraft type (747) has 3 such switches: one next to the radio, one on the steering column, and one on the hand microphone. The two on the radios and steering column have two settings, one is for the interphone and one is for the radio. So you would have to switch it in the right way as well.&lt;/li&gt;&#xA;&lt;li&gt;Once you actually talk to ATC, you would possibly be connected to someone from the airline who knows the exact layout of the panels, as each airline can order different configurations and extra options etc. Most of the primary flight displays are usually the same, but there are minor differences. &lt;/li&gt;&#xA;&lt;li&gt;They would talk you through setting up the aircraft for a fully automated landing. This would include:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;descending and navigating to a location where you could “attach the aircraft systems to the runway landing system” — intercept heading for an ILS (instrument landing system) approach&lt;/li&gt;&#xA;&lt;li&gt;setting up the autopilot and FMS (flight management systems) for that approach&lt;/li&gt;&#xA;&lt;li&gt;set the autobrakes etc. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;This would require a lot of patience and time, but I do think it is possible, once the aircraft has landed it would automatically brake to a full stop and keep rollout guidance (stay on the runway). &lt;/li&gt;&#xA;&lt;li&gt;If any extra abnormality occurs it would be highly unlikely the person would be able to solve that&lt;/li&gt;&#xA;&lt;li&gt;I think the most important factor here is time, patience and the ability for the passenger to listen and not panic. Time = fuel, so that’s always of the utmost importance. &lt;/li&gt;&#xA;&lt;li&gt;Given it happens more than 100 NM (nautical miles) away from the airport you would land on you would have to switch multiple times from ATC centers. Just hope you would be able to do that and get in contact with the new center. So let’s hope we’re all wise enough to have you talk on 121.5 (international emergency frequency) and stay there.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, if this happens over, for instance, the ocean you might be talking on HF, very bad radio quality and most probably not the radio which is selected at that time, so getting in contact with ATC might prove difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for getting into the cockpit, with a bit of ingenuity or help that should be fairly straightforward, even with all the new cockpit doors etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you’re smart, you would call the airline with a credit card phone from the cabin first if absolutely no one including stewardesses, who don’t know how to operate the radios etc.,  knows what to do.&lt;/p&gt;&#xA;" OwnerUserId="3854" LastEditorUserId="2143" LastEditDate="2014-10-10T18:57:46.160" LastActivityDate="2014-10-10T18:57:46.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9036" PostTypeId="2" ParentId="8913" CreationDate="2014-10-10T18:01:35.580" Score="1" Body="&lt;p&gt;5000 feet would be the minimum runway size under normal conditions and even this would be dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To land on a 2500 is possible but would require arresting equipment and a pilot with balls of steel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it were me, I would flood the runway with some kind of heavy mud, like drilling fluid or a non-flammable oil. That would probably do it. I would obviously do some physical calculations to make sure it would work before trying it.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-10-10T18:01:35.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9037" PostTypeId="2" ParentId="8986" CreationDate="2014-10-10T18:29:55.587" Score="4" Body="&lt;p&gt;Let's assume physical access to the cockpit is not an obstacle (flight attendant or someone has duplicate key or access code; a crowbar can be obtained; or otherwise a brute force way to get in can be devised.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm going to say the answer to the question is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a passenger has never flown a plane or played with a flight simulator, then there's a &lt;strong&gt;very slim chance&lt;/strong&gt; they will successfully land the plane. There has to be some kind of working knowledge of how aircraft work. This knowledge is crucial and simply can't be imparted by someone trying to talk them through it over the radio. (Can a non-technical passenger even figure out how to use the radio and establish communication with a control tower? Probably not. )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if a passenger has played with flight simulators, the &lt;strong&gt;probability of success rises greatly&lt;/strong&gt;. In other words, now it's actually in the &quot;tens of percent&quot; (10%, 20%, 30%) versus hundredths of percentile (0.001%). That's because flight simulators are pretty accurate representations of real flying, and in order to use a flight simulator successfully, you actually have to first learn the fundamentals of how airplanes work (gliding, stalling, dealing with wind, how to line up for the runway, etc). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if a passenger has piloted some sort of real aircraft, then it increases the chances a bit more, although probably not a huge amount compared to the simulator-only case. At this point, it is a matter of the passenger learning where the minimum essential controls are, how to take the plane off autopilot if that's what's needed. Knowing which are the essential controls and ignoring the rest of the control panel. And knowing how to navigate to the nearest airstrip. Assuming this information can be imparted by someone (control tower people over the radio), then I would say there's a 95% chance of making it to the airstrip and maybe a 50% chance of successful landing. As someone else mentioned, the touchdown is the crucial moment. Someone who has landed a single engine prop isn't going to know how a 737 feels. &lt;/p&gt;&#xA;" OwnerUserId="2849" LastActivityDate="2014-10-10T18:29:55.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9038" PostTypeId="2" ParentId="8950" CreationDate="2014-10-10T19:23:38.190" Score="4" Body="&lt;p&gt;As others have pointed out, the plane that would benefit from towing would go down before it could be reached by a tow plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the tow plane could catch up to the glider it would be difficult to do the hookup quickly. You would need some kind of special apparatus to capture the tow hook and attach it. Doing this would be very difficult because the aircraft would be in different configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, lets say it is two 737, one with engines out. The stall speed for a 737 is 150 knots, so it might be going, say 180 knots with a glide ratio of 15:1. At this rate it will be descending at 1200 ft/min. That is a FAST descent rate, almost crashing/out of control. For example, if you descend faster than 1000 ft/min in a flight test you will be automatically failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cruising speed for the tow plane is 450 knots, so he would have to somehow slow down to 180 knots AND be descending at 1200 ft/min AND stay directly in front of the glide plane while the hookup occurred. Doing all three of these things would be very, very difficult.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-10-10T19:23:38.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9039" PostTypeId="1" CreationDate="2014-10-10T19:57:21.723" Score="4" ViewCount="667" Body="&lt;p&gt;I am trying to find information on aircraft N58644 which doesn't show on the N number listing. This is a BT-13A converted to civilian use from the 40s or 50s. Any ideas where I can get any information since the FAA doesn't show it?&lt;/p&gt;&#xA;" OwnerUserId="3866" LastEditorUserId="572" LastEditDate="2015-02-24T10:59:50.130" LastActivityDate="2015-02-24T10:59:50.130" Title="How can I find information about the aircraft with registration / tail-number N58644?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9040" PostTypeId="1" AcceptedAnswerId="9080" CreationDate="2014-10-10T20:03:09.887" Score="11" ViewCount="4519" Body="&lt;p&gt;At the pilot-controlled airfield I use most frequently, we fly a standard rectangular pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CQHK2.jpg&quot; alt=&quot;Standard left traffic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The normal-landing C172 flap sequence goes&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Downwind: 10 degrees past the “abeam point” and airspeed in flap range&lt;/li&gt;&#xA;&lt;li&gt;Base: 20 degrees&lt;/li&gt;&#xA;&lt;li&gt;Final: 30 degrees when assured of making the runway&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;When making occasional landings at a nearby Class C airport, ATC sometimes puts me on vectors resulting in a long, straight-in final. In relation to such an approach, when do I extend flaps to 10, 20, and 30 degrees?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="62" LastEditDate="2014-12-08T14:39:08.467" LastActivityDate="2014-12-08T14:39:08.467" Title="In a Cessna 172 flying VFR on long final, when do I extend flaps to 10, 20, and 30 degrees?" Tags="&lt;visual-flight-rules&gt;&lt;approach&gt;&lt;flaps&gt;&lt;traffic-pattern&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9042" PostTypeId="1" AcceptedAnswerId="9046" CreationDate="2014-10-11T00:07:17.997" Score="4" ViewCount="747" Body="&lt;p&gt;So, I have a hypothetical aircraft that needs to get from FL350 to 10,000' as quickly as possible.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the difference in sink rate between a 'standard' airliner rapid descent (idle thrust, extended spoilers, and nose slightly down) vs. having the flight crew simply point the nose down below the horizon as far as they care to?&lt;/li&gt;&#xA;&lt;li&gt;How does the airspeed build-up over time differ between a 'standard' rapid descent vs. a dive?&lt;/li&gt;&#xA;&lt;li&gt;For a rapid descent, what nose-down pitch would be typical?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="572" LastEditDate="2015-02-24T10:58:59.920" LastActivityDate="2016-09-28T06:51:57.030" Title="How do pitch attitude, airspeed and sink rate come into play in a rapid descent or a dive?" Tags="&lt;emergency&gt;&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9043" PostTypeId="2" ParentId="9040" CreationDate="2014-10-11T00:40:33.330" Score="6" Body="&lt;p&gt;I visualise the standard lengths of the pattern and pretend I'm simply doing them in a straight line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure you could figure out precise lengths or time intervals if you wanted to, but ultimately in a 172 in VFR you don't need to be exact - you just need to be fully configured and established by the usual point on final approach, as if you were completing a circuit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trap many people find with a straight-in approach is they leave everything too late - downwind checks, flap, etc. Make sure you allow enough room for about 15-30 seconds between flap extension, otherwise you'll find it difficult to maintain the approach angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with everything, a good straight in approach takes practice!&lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-11T00:40:33.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9044" PostTypeId="2" ParentId="9042" CreationDate="2014-10-11T01:48:43.890" Score="0" Body="&lt;p&gt;'Dives' in an airliner should really be avoided at all costs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A nose-down dive could have the following dangers, just to name a few:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Excessive airspeed, leading to structural integrity issues&lt;/li&gt;&#xA;&lt;li&gt;The 'pull out' would have a high load factor (think high G force) which would stall the aircraft (or even break it apart)&lt;/li&gt;&#xA;&lt;li&gt;To 'pull out' without stalling would take a long time to level off - it would be easy to overshoot the 10k feet mark and if there's high terrain...&lt;/li&gt;&#xA;&lt;li&gt;You would have a cabin-load of vomiting passengers! &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The standard emergency descent procedure will get you to a safe altitude quickly enough, with oxygen supplemented. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sorry I can't answer your other questions but I hope I have explained why a dive would not be a viable option. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-11T01:48:43.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9045" PostTypeId="1" AcceptedAnswerId="9083" CreationDate="2014-10-11T02:49:32.703" Score="14" ViewCount="1519" Body="&lt;p&gt;So, let us assume you are in a simulator for your favorite jet plane, and the instructor gives you a LOFT (Line-Oriented Flight Training) scenario that goes as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A normal takeoff and climb to cruise altitude, and perhaps thirty minutes of normal cruise flight&lt;/li&gt;&#xA;&lt;li&gt;The non-recoverable loss of speedbrake (flight spoiler) functionality due to a mechanical jam, or some other malfunction such as the loss of all SECs in a FBW Airbus.&lt;/li&gt;&#xA;&lt;li&gt;Another 30 minutes of time to deal with the first malfunction: run the checklists, plan and initiate a diversion if needed.&lt;/li&gt;&#xA;&lt;li&gt;You lose normal cabin pressure for some reason, and have to conduct a rapid descent to get back to 10,000' and complete your diversion.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;How do you execute the descent, considering that the rapid descent procedures for most jets rely on using the speedbrakes to achieve a high descent rate without overspeeding the aircraft?  To use the 737 QRH checklist for Emergency Descent as an example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EMERGENCY DESCENT . . . . . . . . . . . . . . . . . . . . . .Announce&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The captain will advise the cabin crew, on the PA system,&#xA;  of impending rapid descent. The first officer will advise&#xA;  ATC and obtain the area altimeter setting.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ENGINE START switches . . . . . . . . . . . . . . . . . . . . . . . . CONT&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;THRUST levers . . . . . . . . . . . . . . . . . . . . . . . . . . . . CLOSE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Reduce thrust to minimum or as needed for anti-ice.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;SPEED BRAKE . . . . . . . . . . . . . . . . . . . . . . . . . FLIGHT DETENT&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DESCENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Initiate&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Target speed . . . . . . . . . . . . . . . . . . . . . . . . . . . Mmo/Vmo&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If structural integrity is in doubt, limit speed as much as&#xA;  possible and avoid high maneuvering loads.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Level-off altitude . . . . . . . . . . . . . . . . . . . Lowest safe altitude&#xA;                                            or 10,000 feet, whichever is higher&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="97" LastEditDate="2015-05-03T00:41:33.330" LastActivityDate="2018-04-24T19:17:18.530" Title="How to do a Rapid Descent in a jet with inoperative spoilers?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;emergency&gt;&lt;cabin-pressure&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9046" PostTypeId="2" ParentId="9042" CreationDate="2014-10-11T03:35:07.057" Score="5" Body="&lt;p&gt;Airspeed control is the difference. In a rapid descent, airspeed is controlled and the pilots will keep it below $v_D$, the maximum dive speed for which the aircraft is certified. For a modern airliner, this is somewhere around Mach 0.9.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a dive with &quot;nose down as far as they care to&quot; (I read this as 90°), airspeed is not controlled, but an outcome of the situation. The airliner will go supersonic. It is possible to recover it from a short dive, but will incur damage to the aircraft (e.g. the pilots will need to lower the landing gear to increase drag, but lose the gear doors in the process).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilots would only care to put the nose down to the point where they not exceed $v_D$, we are back at a rapid descent. They could lower the gear in order to increase the sink speed, and circle to increase drag further. Circling needs more lift (proportional to the inverse of the cosine of the bank angle), so more lift-induced drag is produced. To maximize drag, the pilots should fly at the maximum permissible load factor (which is rather low at maximum dive speed due to gust loads).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume the L/D of the airliner to be 5 with gear and spoilers deployed, the pitch attitude would be between -11° and -12° and the sink speed would be between 50 and 60 m/s (10,000 to 12,000 ft/min). The bank angle would be between 45° and 60° and the plane would be violently shaken by buffeting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going any steeper than that would only be attempted by pilots with suicidal leanings. Flying like described above is scary enough already.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-09-28T06:51:57.030" LastActivityDate="2016-09-28T06:51:57.030" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9047" PostTypeId="2" ParentId="9045" CreationDate="2014-10-11T03:43:54.943" Score="7" Body="&lt;p&gt;Go to the top right corner of the envelope and stay there (point D in the sample below. Sorry, I don't have the 737 envelope at hand). Engines idle, speed and load factor as high as allowed.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/h6GZP.png&quot; alt=&quot;flight envelope&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If airframe integrity is not critical, lower the gear to increase drag, but expect to lose the gear doors.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-11T03:55:23.973" LastActivityDate="2014-10-11T03:55:23.973" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9048" PostTypeId="1" AcceptedAnswerId="9053" CreationDate="2014-10-11T05:38:29.163" Score="8" ViewCount="14086" Body="&lt;p&gt;Have hung around some of the aviation interest groups (like airliners.net) and tried to research this but haven't found very clear answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically when a hurricane (tropical, peak wind-speed in excess of 100 mph) makes landfall, it sheds most of it's energy and water near the coast-line, however the rainfall and wind-speed heat-map (that is elevated beyond the seasonal average) may be over a very large area. Also a hurricane might move at a speed such that the weather conditions might change the large area (covered by the heat-map) over 2-3 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my questions in view of the above understanding are: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Whether normal flight operations continue (barring the to/from the airports that are directly under the hurricane path), in this vast other region that is part of the heatmap? (Say with airports in areas showing rainfall up to 3 inches, and windspeeds upto 50-60 mph.)&lt;/li&gt;&#xA;&lt;li&gt;If commercial airlines do operate in such weather, what should I expect the ride to be like?&lt;/li&gt;&#xA;&lt;li&gt;What are the chances of such flights being diverted?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here is the &lt;a href=&quot;http://www.webcitation.org/6TEkg3YQp&quot; rel=&quot;nofollow&quot;&gt;WebCite archived webpage&lt;/a&gt; (so this link won't go away) of Weather.com that I am referring to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. I plan to take a flight from Bangalore to Delhi to Kathmandu, on Monday, as the tropical cyclone (as it is called here in Indian subcontinent) is about to make landfall on the eastern coast of India around noon, and we are expecting upto 3 inches of rainfall and winds upto 60mph here on Monday morning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wanted to see if I should seriously consider rescheduling flights. A call to my airline customer-care yielded no useful information, and they seemed rather clueless. I read in the local newspaper that train services are being shutdown in the affected area, although it seems to be more like trains that pass through the area with the maximum impact.&lt;/p&gt;&#xA;" OwnerUserId="3872" LastEditorUserId="97" LastEditDate="2015-05-03T00:39:23.233" LastActivityDate="2018-09-11T19:02:00.857" Title="Do airlines continue operating in the vicinity of a hurricane?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;weather&gt;&lt;turbulence&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9049" PostTypeId="1" AcceptedAnswerId="9055" CreationDate="2014-10-11T06:57:46.973" Score="8" ViewCount="11092" Body="&lt;p&gt;There is little doubt on whether planes can fly over a tropical cyclone as clearly demonstrated by &lt;a href=&quot;http://www.youtube.com/watch?v=QVPWSdMzghY&quot;&gt;this video&lt;/a&gt; of a Gulfstream jet flying over hurricane Katrina in 2005 to drop weather instruments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know the intensity of cyclonic wind at 10km above sea level, but my limited understanding on the subject suggest that the wind is strongest near the surface and weakens with height. If a small plane with high service ceiling can fly over such a powerful storm. Is it possible for a larger plane with a lower service ceiling to fly into a cyclone unscathed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering that most pilots would try to go around a cyclone and that safety regulations may also forbid pilots from putting their passengers in any kind of risk that airlines do not want to bear, by just strictly looking at the aerodynamics and aeronautics of the aircraft, is it feasible for large commercial planes like 747 to fly into a tropical cyclone?&lt;/p&gt;&#xA;" OwnerUserId="1390" LastActivityDate="2014-10-11T18:02:54.133" Title="Can a commerical jet fly into a tropical cyclone?" Tags="&lt;commercial-aviation&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9051" PostTypeId="2" ParentId="9049" CreationDate="2014-10-11T13:11:01.863" Score="4" Body="&lt;p&gt;Fly right into a cyclone? Unlikely the plane has been tested for it, and unless the pilot was a former P-3 / C-130 Hurricane Hunter pilot (or has both balls and stomach of steel) unlikely they will try.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P-3 orion and Hercules aircraft have flown into storms many times. They weren't built especially strong other than being a standard military aircraft. A U-2 was used for hurricane research once, and that aircraft is basically flying tinfoil. I suspect it was far enough above the storm that it didn't notice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, and this is purely speculative, I think a 747 can take a lot more abuse than it regularly gets. But as the cost of failure is rather high I don't think anyone wants to be first (and possibly last) to try it.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-11T13:11:01.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9052" PostTypeId="1" AcceptedAnswerId="9078" CreationDate="2014-10-11T15:28:51.103" Score="15" ViewCount="8959" Body="&lt;p&gt;I found this &lt;a href=&quot;https://aviation.stackexchange.com/questions/1950/what-are-the-general-post-flight-sequence-checks-and-do-they-start-automatically&quot;&gt;question&lt;/a&gt;. One of the answer tell the flaps are generally retracted after landing. I assume this mean flaps are retracted when the airplane is on the ground between flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps are extended for landing and then extended again for take off. Not taking care of their position while on ground (no need of them) and putting them in the required position before take off may save (few) flaps actions (something like putting them from landing to take-off position instead of landing position to fully retracted and then from retracted to take-off position).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some good reason to retract the flaps on ground? Does this good reason varies from a type of aircraft to another?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-05-27T00:24:59.030" Title="Why are flaps retracted when an aircraft is parked on ground?" Tags="&lt;flaps&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9053" PostTypeId="2" ParentId="9048" CreationDate="2014-10-11T16:48:15.610" Score="8" Body="&lt;p&gt;The cross-wind limit is 35-40 &lt;em&gt;knots&lt;/em&gt; for most aircraft with gusts allowed to perhaps 45 or so. The head-wind limit is slightly higher, but not much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knot is nautical mile per hour. Nautical mile is 1.852 km, that is 1.15 mile (and for those who prefer metric, knot is just a bit over ½ m/s). So wind more than 40 miles/hour may interrupt airport operations and wind more than 50 miles/hour surely will. I don't think there is a specific limit for rain; it is generally not a big problem if the runways are in good condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Problem is that good local forecasts are possible for at most around 24 hours. So it's not possible to tell whether it is likely there will be disruption of operations the day after tomorrow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For one day ahead, the airport forecasts are publicly available on the internet. Search for TAF (&quot;terminal aerodrome forecast&quot;) with the ICAO (the 4-letter one) code of the airport. They are published in strange abbreviations, but there are sites that will happily decode it for you.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2018-09-11T19:02:00.857" LastActivityDate="2018-09-11T19:02:00.857" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9055" PostTypeId="2" ParentId="9049" CreationDate="2014-10-11T18:02:54.133" Score="9" Body="&lt;p&gt;If the wind shear (sometimes called wind gradient, which in my opinion is the better term) encountered in that part of the cyclone the aircraft is penetrating is less than what the aircraft can handle, then, yes, an aircraft can safely fly into a cyclone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the aircraft can handle varies greatly depending on the speed at which it is being flown. Large aircraft have a recommended turbulence penetration speed, both in terms of knots and mach. In the absence of such a recommendation, V speeds that are relevant are Va, Vb, and Vo. &lt;a href=&quot;http://en.wikipedia.org/wiki/V_speeds&quot;&gt;http://en.wikipedia.org/wiki/V_speeds&lt;/a&gt; is a good V speed terminology reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know what typical wind gradient values within a cyclone are or what their distribution within the cyclonic area is. However, I would be surprised if they were significantly greater than gradients within tropical thunderstorms, and aircraft do penetrate such.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In season there's a roughly north-south line of thunderstorms that regularly develops between Sumatra and Sri Lanka with tops greater than 50,000 feet. Lacking the fuel to go around the line, we would regularly go through it using radar to avoid the worst. However, with those old radars (back in the 1990s in 747s), it was not uncommon for us to wind up in a cell.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-10-11T18:02:54.133" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9056" PostTypeId="1" AcceptedAnswerId="9070" CreationDate="2014-10-11T18:39:58.407" Score="22" ViewCount="4557" Body="&lt;p&gt;There are several airfields nearby where parachuting activities routinely take place. How far away is considered to be a safe distance from the airfield when flying past it en-route to another destination? Are there any particular frequencies to monitor besides the airfield frequency? How would I know parachuting is happening besides any NOTAMs?&lt;/p&gt;&#xA;" OwnerUserId="3670" LastEditorUserId="3887" LastEditDate="2014-10-12T16:23:31.177" LastActivityDate="2014-10-13T16:03:56.070" Title="What should a pilot do when flying in the vicinity of parachute jumpers?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;parachute&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9057" PostTypeId="2" ParentId="9056" CreationDate="2014-10-11T19:16:04.513" Score="11" Body="&lt;p&gt;First of all, recurring DZ's have parachute symbols on sectional charts, so look for them! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA regulations have this to say:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Federal Aviation Regulation Part 105.25 requires that ATC be notified no earlier than 24&#xA;hours before or no later than one hour before the parachute operation begins in Class E &#xA;and G airspace. Jumps in Class A, B, C and D airspace require an authorization from ATC. &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This means that if you expect chute activity in the area, ask ATC!&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Controllers are required to give traffic advisories to jump aircraft before the jump,&#xA;and to issue advisories to all known aircraft that will transit the Class E airspace &#xA;within which the jump operations will occur. When time or the number of aircraft make &#xA;individual transmissions impractical, advisories to nonparticipating aircraft may be &#xA;broadcast on appropriate frequencies.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;And as always, check the NOTAMS!&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2014-10-11T19:16:04.513" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9058" PostTypeId="2" ParentId="9056" CreationDate="2014-10-11T19:18:16.403" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any particular frequencies to monitor besides the airfield&#xA;  frequency? How would I know parachuting is happening besides any&#xA;  NOTAMs?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here in Seattle, jump aircraft are usually talking with ATC (Seattle Approach). The jump airplane will announce 5 minutes out and the when the jump occurs.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2014-10-11T19:18:16.403" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9059" PostTypeId="1" CreationDate="2014-10-11T19:24:34.423" Score="4" ViewCount="326" Body="&lt;p&gt;Can anyone find Putin's Il-96-300PU July 17 flight track?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putin's flight path has not been publicized on the internet. The Russian media is claiming that his aircraft would be in danger of being shot down, but has not shown that he would be even over Ukraine.  Initial information indicated that he was flying through Poland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a flight track for Vladimir Putin's aircraft on July 17?&lt;/p&gt;&#xA;" OwnerUserId="3877" LastEditorUserId="167" LastEditDate="2014-10-12T03:02:49.173" LastActivityDate="2014-10-12T03:02:49.173" Title="Can anyone find Putins Il-96-300PU july 17 flight map?" Tags="&lt;air-traffic-control&gt;&lt;flight-planning&gt;&lt;radar&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2014-10-12T00:03:44.127" ContentLicense="CC BY-SA 3.0" />
  <row Id="9060" PostTypeId="2" ParentId="9045" CreationDate="2014-10-11T19:36:17.837" Score="3" Body="&lt;p&gt;Whenever trying to rapidly descend, you always want to think drag!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Throttle to idle, lots of s-turns, (aileron drag), get down to gear speed, drop the gear, and lower flaps if practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A limited crabbing-like manuever (intentional side-slipping) would greatly slow the aircraft as well!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure that Terry will be here to recant us with a tale soon!&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="3048" LastEditDate="2014-10-12T16:49:44.537" LastActivityDate="2014-10-12T16:49:44.537" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9061" PostTypeId="2" ParentId="9052" CreationDate="2014-10-11T19:40:06.707" Score="17" Body="&lt;p&gt;You never know what wind speed will hit the aircraft until the crew returns. Also, retracted flaps are much less of an obstacle to careless drivers of airport trucks. &lt;a href=&quot;https://www.youtube.com/watch?v=cHhZwvdRR5c&quot;&gt;This video&lt;/a&gt; shows a parked 747 in high winds. Now imagine what would have happened if the flaps had been deployed!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that fully extended high lift systems at ground angle of attack can produce five or six times the lift of the wing with flaps retracted. Lowering the trailing edge flaps increases wing area and lowers the zero-lift angle of attack, so at ground attitude the wing is much farther up on the lift curve slope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft with manual controls it is also recommended to secure all control surfaces, so they don't float in the wind. Bearings and pushrods could be damaged, and in a careless preflight check might not raise suspicions, but can go on to fail in flight. Better be safe and reduce all chances of wind playing with the aircraft!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-11T19:40:06.707" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9062" PostTypeId="1" AcceptedAnswerId="9067" CreationDate="2014-10-11T20:48:06.043" Score="7" ViewCount="5200" Body="&lt;p&gt;When a commercial passenger airliner suffers a rapid decompression, it is critical that everybody on board gets oxygen quickly. In the passenger rows, oxygen masks connected to chemical oxygen masks will drop. In the cabin, the flight crew will pull out their oxygen masks, which are connected to pressurized oxygen canisters. The chemical generators will last for 10-15 minutes, but apparently the flight crew's oxygen supply will last for a couple of hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would the flight crew's supply last for so much longer? If the plane isn't at a breathable altitude after 30 minutes, it seems like it'd probably be unrecoverable, and the passengers will be in irreversible comas anyway.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2014-10-11T23:21:51.000" Title="Why do pilots' masks have more oxygen?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;passenger&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9063" PostTypeId="1" AcceptedAnswerId="9092" CreationDate="2014-10-11T21:12:04.973" Score="12" ViewCount="6558" Body="&lt;p&gt;Let's say an commercial passenger jet is accelerating down the runway, taking off. The ATC receives some signal that he/she should cancel all takeoff clearances.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Exactly what happens in the control room?&lt;/li&gt;&#xA;&lt;li&gt;What does the ATC do and how does he/she make sure pilots understand the cancellation?&lt;/li&gt;&#xA;&lt;li&gt;How do the pilots in the aircraft taking off respond? Are they trained for this scenario?&lt;/li&gt;&#xA;&lt;li&gt;Is a takeoff cancelled even after &lt;em&gt;V1&lt;/em&gt;?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2448" LastEditorUserId="2448" LastEditDate="2014-10-13T08:08:51.333" LastActivityDate="2017-01-30T16:39:08.890" Title="What happens when a takeoff clearance is cancelled by the ATC?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;takeoff&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9064" PostTypeId="2" ParentId="9062" CreationDate="2014-10-11T21:13:55.793" Score="6" Body="&lt;p&gt;Limited space and weight come into play.  As well as the fact that sufficient air to keep one alive is not enough for peak performance.  The masks for passengers are enough to keep the passengers alive during the descent to a survivable air pressure.  Once there, the pilots will still want more oxygen so they can better deal with the emergency (and landing preparations).&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-10-11T21:13:55.793" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9065" PostTypeId="2" ParentId="9063" CreationDate="2014-10-11T21:45:38.510" Score="12" Body="&lt;p&gt;Tower will tell the pilot that take off clearance is revoked and the pilot will hit the brakes hard in the standard abort takeoff procedure unless the plane already passed V1 then he will continue the takeoff while hoping the reason won't hit the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After V1 the plane is committed to taking off because it won't be able to stop in time before the end of the runway.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-11T21:45:38.510" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9066" PostTypeId="1" AcceptedAnswerId="9068" CreationDate="2014-10-11T23:21:23.863" Score="60" ViewCount="31957" Body="&lt;p&gt;Typically jets cannot operate when intake airflow is supersonic relative to the engine. Why is this so? Also, why are scramjets able to use supersonic air?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To slow down the air to subsonic speeds, the air passes through a shockwave (if I understand correctly). How does this slow down the air?&lt;/p&gt;&#xA;" OwnerUserId="3878" LastActivityDate="2019-02-17T14:27:43.990" Title="Why can't jet engines operate with supersonic air and how do they slow it down?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="9067" PostTypeId="2" ParentId="9062" CreationDate="2014-10-11T23:21:51.000" Score="15" Body="&lt;p&gt;The pilots also need to use oxygen in case of smoke, fumes, or fire in the aircraft.  Thus, they need enough oxygen to be able to get down and land in a fire scenario, which is much more than a decompression!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fire procedures have the crew on 100% oxygen at positive pressure to prevent them from breathing in smoke and fumes, while in a decompression, their masks mix oxygen with cabin air, in much the same way the cabin masks do.  This is also why the cabin masks are not used in smoke/fumes scenarios.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2014-10-11T23:21:51.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9068" PostTypeId="2" ParentId="9066" CreationDate="2014-10-11T23:49:04.157" Score="41" Body="&lt;p&gt;To avoid shock waves on the compressor blades which would make the engine unusable both because of the very large pressure fluctuations that would cause fatigue and failure of blades and because of the high level of drag that is developed in supersonic flows that would have the effect of slowing the blades down as they rotated. In fact, the engine just wouldn't run with a supersonic flow going into it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the flow needs to be slowed down as much as possible to allow enough time in the combustion chamber for the fuel to burn completely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So... a cone or ramp shape at the inlet is used to create a little shockwave in front of the engine slowing down the incoming air to subsonic speeds and allowing the jet engine to operate efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ramjet is able to use the compressed air because it is designed to do so. An excellent case study is the SR-71 Blackbird, which had engine cones that moved forward and backward based on speed/altitude, to transition from a turbine to a ramjet mission profile. (Fun fact: That plane is so darned fast that the limit to its speed comes not from engine power, but from &lt;em&gt;MELTING THE PLANE&lt;/em&gt; because it is going so fast.) The SR-71 had &quot;Bypass doors&quot; to close of the main turbine of the engine when operating on a ramjet profile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;ramjet&lt;/strong&gt; sometimes referred to as a flying stovepipe or an athodyd, is a form of airbreathing jet engine that uses the engine's forward motion to compress incoming air without a rotary compressor. Ramjets cannot produce thrust at zero airspeeds; they cannot move an aircraft from a standstill. A ramjet powered vehicle, therefore, requires an assisted take off like a JATO to accelerate it to a speed where it begins to produce thrust. Ramjets work most efficiently at supersonic speeds around Mach 3. This type of engine can operate up to speeds of Mach 6.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nwUTv.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;scramjet&lt;/strong&gt; is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to forcefully compress the incoming air before combustion, but a ramjet decelerates the air to subsonic velocities before combustion, while airflow in a scramjet is supersonic throughout the entire engine. This allows the scramjet to operate efficiently at extremely high speeds: theoretical projections place the top speed of a scramjet between Mach 12 and Mach 24.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="37321" LastEditDate="2019-02-17T14:27:43.990" LastActivityDate="2019-02-17T14:27:43.990" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="9070" PostTypeId="2" ParentId="9056" CreationDate="2014-10-12T00:44:01.627" Score="17" Body="&lt;p&gt;Qualification: I worked at a busy drop zone for 10 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just announce yourself on the airfield frequency about 5-10 minutes out and they'll tell you what's going on, including which runway is active and how high they are jumping from - standard altitudes are 3000ft and 12,000ft AGL. At our place it was really simple: left-hand for 34, right-hand for 16. We landed everyone on the east side, and if we are dropping at 3000 all day you can just pop up to 4000 and be completely out of the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under no circumstances make a cross-field pass as that's usually right in the middle of everyone else's landing pattern, and we don't carry radios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are just passing by a 2km buffer is lots - no one is likely to be in the air that far away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No reply usually means nothing in the air.  &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-12T00:44:01.627" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9071" PostTypeId="1" AcceptedAnswerId="9090" CreationDate="2014-10-12T07:39:50.763" Score="4" ViewCount="516" Body="&lt;p&gt;I heard somewhere that airlines pay the airport depending on the time spent at the gate. Suppose there are weather conditions that cause the aircraft to be delayed at the gate, such as heavy rain lasting few minutes, snow requiring half the runway to be closed to remove the snow, and so on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happen in those exceptional conditions? Does the airport still charge the airline for all the time spent at the gate? Is there special tariff for exceptional weather conditions?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="946" LastEditDate="2014-10-12T09:27:28.810" LastActivityDate="2014-10-13T08:23:30.490" Title="Do airports charge airlines for extra time spent on ground due to weather conditions?" Tags="&lt;airport&gt;&lt;airlines&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9072" PostTypeId="1" AcceptedAnswerId="9081" CreationDate="2014-10-12T09:40:11.990" Score="6" ViewCount="8549" Body="&lt;p&gt;In one episode of the 'reality' show &lt;a href=&quot;http://en.wikipedia.org/wiki/Airplane_Repo&quot; rel=&quot;noreferrer&quot;&gt;Airplane Repo&lt;/a&gt; a pilot topped off an aircraft engine with motor oil; I think it was a Cessna 182 but I may be wrong. What would be the effect on the engine? Is it a practical (and safe) alternative if aviation oil isn't available?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2017-10-04T20:25:15.367" Title="Can I use motor oil in a aircraft piston engine?" Tags="&lt;piston-engine&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9073" PostTypeId="2" ParentId="9063" CreationDate="2014-10-12T09:47:39.020" Score="1" Body="&lt;p&gt;Your quote suggests that AM-18 aborted take-off because of ATC instruction, but if you read the article carefully it's &lt;em&gt;not&lt;/em&gt; the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AM-18 was accelerating for take-off when the crew noticed something is wrong with the tires (probably blown tire already) and aborted just below V1 due to their own decision.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Exactly what happens in the control room?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't know exactly, but there are various sensors designed to warn of possible runway incursions. Apparently the sensors detect aborted take-off and alerted the controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some places, including USA, the controllers will clear aircraft to take-off or land when they &lt;em&gt;expect&lt;/em&gt; the runway will be clear by the time the aircraft reaches it. So they have to cancel that clearance when there is an incident and the previous aircraft does not vacate the runway as happened here. In other places, e.g. Europe, they don't do this, so they don't have to cancel any clearances, but the pilots are often receiving their clearances at the last moment which has it's own disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;What does the ATC do and how does he/she make sure pilots understand the cancellation?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They cancelled clearance of the &lt;em&gt;next&lt;/em&gt; flight that was just about to line up behind AM-18. I believe &quot;cancel&quot; is standard wording, so something like &quot;tower, XYZ, take-off clearance cancelled; line up and hold.&quot; They know the pilot understood since the pilot reads back the instructions in reply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;If&lt;/em&gt; the aircraft has already commenced take off roll (which didn't happen here), time becomes critical, so then the instruction is just &quot;XYZ, stop immediately&quot;, often repeated twice, or until the aircraft starts to brake or the pilots answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does happen now and then. See for example &lt;a href=&quot;http://avherald.com/h?article=441a6441&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; incident.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;How does the pilots respond? Are they trained for this scenario?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the clearance is changed, the pilots simply follow the new instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If &quot;stop immediately&quot; is requested, pilots abort the take off &lt;em&gt;if possible&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot does see the problem (nobody will request aircraft in take-off roll to stop unless there is a serious risk of collision), which they often do, they may decide to continue the take-off if it's more likely they'll lift off before the obstacle than that they stop before it. Captain is the final authority responsible for safety of the aircraft, so it's their call.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Is a takeoff cancelled even after &lt;em&gt;V1&lt;/em&gt;?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, because the aircraft is no longer able to stop on the remaining runway. Instead the pilot may rotate earlier. The Vr is higher than Vmu, so they can rotate at slightly lower speed and they can increase thrust if they are doing reduced thrust (&quot;flex&quot;) take-off, which they now usually do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example in &lt;a href=&quot;http://avherald.com/h?article=46ea71df&quot; rel=&quot;nofollow noreferrer&quot;&gt;this incident&lt;/a&gt; ATC instructed the crew to abort (but failed to follow correct phraseology). At the same time the crew noticed the problem themselves, but they were already above V1 and decided they can fly over the obstacle and not stop before it and therefore continued the take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that at V1 the aircraft is already long way down the runway, so the obstacle  is likely near the end of the runway and likely can be already seen by the pilot, so the pilot decides how they try to avoid the collision.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="16971" LastEditDate="2017-01-30T16:39:08.890" LastActivityDate="2017-01-30T16:39:08.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9074" PostTypeId="1" CreationDate="2014-10-12T10:26:23.610" Score="1" ViewCount="674" Body="&lt;p&gt;A government agency of an EU country commissions a private company with a chartered flight from Europe to Africa/Asia/... (e.g. to involuntarily take people to a specific country).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then it wants to change the time of departure with short notice. How long before the changed departure time do they need to file the new flight plan and what are some obstacles for changing it at the last minute? &lt;/p&gt;&#xA;" OwnerUserId="3883" LastEditorUserId="572" LastEditDate="2015-02-19T08:58:53.170" LastActivityDate="2015-02-19T08:58:53.170" Title="What lead time is required to change an already submitted flight plan?" Tags="&lt;flight-planning&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9075" PostTypeId="2" ParentId="9056" CreationDate="2014-10-12T12:56:16.800" Score="5" Body="&lt;p&gt;In Europe, it's generally a good idea to be on the &lt;strong&gt;Flight Information Service&lt;/strong&gt; (FIS) frequency, where you can receive information about active drop zones and/traffic information to the airplane performing the drop, as they need to call in on the FIS frequency and announce when they start the drop.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-10-12T12:56:16.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9076" PostTypeId="2" ParentId="8991" CreationDate="2014-10-12T14:29:21.987" Score="13" Body="&lt;p&gt;Actually, a commercial airliner &lt;em&gt;can&lt;/em&gt; do almost &lt;strong&gt;any&lt;/strong&gt; set of legs, assuming those are technically possible (range/payload/laws like ETOPS...) But the main fact that make it possible is &lt;strong&gt;demand&lt;/strong&gt;. If you run an airline, you won't make routes that don't have demand to make profit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation is a complex world. To make profit, you have to consider a massive load of parameters. You can't for example position complete set of crew in every city/airport hotel of your airline routes then decide to create fantasy flights &quot;a la carte&quot;. Crews can't fly continuously aswell, so you can't put crew in a 737 and make them non-stop flights around the country an entire week.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One main thing you have to keep in mind : It's not one or several persons who decide &lt;em&gt;&quot;I want to build an airline with X aircraft on Y routes&quot;&lt;/em&gt;. It's one A-B route that decide how many passengers are available on, then, an airline has the opportunity to operate that route (and struggle to negociate all the authorizations)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some hints about how airliners deals with their environment around the world :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What kind of flights does the airliner, and what airframes does it have in its fleet ?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An airliner can start with one single aircraft, says a DHC6 Twin Otter, and makes regular flights between two airports in the middle of the ocean. You can have 10, 15, maybe 20 round trip a day, some well after sunset.&lt;/li&gt;&#xA;&lt;li&gt;An airliner can have half a dozen ATR or Dash 8, and a set of routes with the proper demand. You can have routes like hub-A-hub, hub-B-hub, when the demand is enough to make each flight profitable. Sometimes, you can't have enough passenger a day on each route, so the airliner makes hub-A-B-C-D-hub the day one, then hub-D-C-B-A-hub on day two, and cycle the sets...&lt;/li&gt;&#xA;&lt;li&gt;An airliner with dozens of (the same) aircraft (737 or A32x) can either have the same round trip hub-X-hub destinations every day, several times a day, airlines like Air France, Southwest, Lufthansa, Air China... or the same fleet, but much more destinations operated two or three times a week : hub-A-B-hub, hub-C-D-E-hub, hub-F-G-H-nightstop-G-F-hub... like Angola Airlines (domestic and regional)&lt;/li&gt;&#xA;&lt;li&gt;Long range flights (7 hours or more) requires the appropriate aircraft. If your airline can buy/lease such an airliner, the route hub-destination-hub can be operated in the limits of the demand. When the demand is enough to fill the plane along the week, then go ahead. Otherwise, the airline has to decide wether a) leave the plane on the tarmac, b) find a nearby complementary route : hub-A-B-hub, hub-B-A-hub, c) use a smaller and cheaper aircraft (if the crew is qualified on) d) combine destination A with a complementary destination B that fills schedules along the week (or bi-week) hub-A-hub-B-hub, e) replace the route with one better, f) negociate with one or several airliners to sell seats to them to fill the aircraft, g) negociate with one or several airliners operating on the destination airport to take advantage of the hubbing : make your airline land at the destination during rush hours.&lt;/li&gt;&#xA;&lt;li&gt;Very long range flights can't be operated every day with one single aircraft. And very long range flights are a niche : the hours spent in that closed tube discourage passengers from taking such flights. And very long range flights are a hell to schedule : the aircraft does 3 or 4 flights a week, and stays on the tarmac the rest of the time.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The size of the airline :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If your airline is a big one, like British Airways or Japan Airlines or United, your reputation and historical operation is enough to get demand on most usual routes (and your staff has the expertise to select profitable ones) Most of your flights will be the type &quot;hub-X-hub&quot;, either domestic, regional, or international.&lt;/li&gt;&#xA;&lt;li&gt;If your airline is above average (like Kenya Airways, Aeromexico, Air India) you'll have a mix of &quot;hub-X-hub&quot; flights and some complementary legs to fix schedules and aircraft operation ratio : hub-A-B(-C)-Hub&lt;/li&gt;&#xA;&lt;li&gt;If your airline is below average (Blue Panorama, Air Kazakstan, Belavia) chances are great to have charter flights, multiple flight shifts.. Timetables greatly vary from one year to another.&lt;/li&gt;&#xA;&lt;li&gt;Small airlines like Air Austral, Republic Express (Indonesia), Insel Air will have historical regular flights, but most of them will be of type &quot;hub-A-B-hub&quot; and/or &quot;hub-A-C-E-C-B-hub&quot;. Timetables also vary from one year to another, but at a less rate than above because the airline don't have enough aircraft to think of new or better routes to operate, as the ones available cannot be closed or replaced.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The region of operation - the airport statistics (passenger volume per year) :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There are regions of high frequency of flights : Western Europe, United States, Japan, South-East Asia, Eastern Australia, the Dubai-Europe axis... In those regions, you have several hundreds of round trip routes that can be operated ten times a day using a Boeing 747. Cheap flights, historical demand, dynamic business. You can operate flights of type &quot;hub-destination-hub&quot;.&lt;/li&gt;&#xA;&lt;li&gt;There are regions with much less traffic, but enought for one airline to operate the simpliest flights hub-dest-hub. However, once another airline or more decide to compete on the same route, everyone is forced to reconsider the way it operates their fleet.&lt;/li&gt;&#xA;&lt;li&gt;You also have regions in the world, especially in Africa and some non-democratic countries out there, where only one airline is allowed to operate a given route. Usually, those airlines don't care about competition, as the state/country itself protect them. Ticket prices on those routes are unusually high, because they can. So the demand on those routes NEVER take off, thus, making the flights on them the same along the years. You'll have destinations operated once a week (if not once a month) You'll have very small airlines and you don't understand why, having the monopoly on the network, they are not able to grow, grow the traffic, and propose better schedules for custommers than the absurd routes and departure/arrival times. Simple : they simply don't care.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Night Flights - jet lag.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You can't just make an aircraft take off, and land when you want. A custommer usually don't want to land at an airport at 3AM.&lt;/li&gt;&#xA;&lt;li&gt;An airline &lt;em&gt;should&lt;/em&gt; avoid boarding passengers at 5:30AM, just because if you board at that time, you've waken up at 3:00AM, failed to take a breakfast, almost forgot your papers, arrives at the airport hungry and angry...&lt;/li&gt;&#xA;&lt;li&gt;jet lag : If you take off from San Francisco at 09:00PM, going to New York, you'll land at 06:25AM. It's okay ! But if you take off at 05:15PM, you'll land at 03:40AM. You haven't slept well.. Perhaps at NY, it's okay to land so early in the morning, but try this in Charles de Gaulle and you'll see how boring (or expensive) it will be. Jet lag is an important factor for international flights. When the airline can't have the slots to land at a proper time at the destination airport, it should think of alternate flights to do, or negociate the opening of an intermediate destination of interest before operating the projected flight, this creating legs like &quot;hub-alternal-hub-destination-hub&quot; or &quot;hub-alternate1-alternate2-destination-hub&quot; or &quot;hub-alternate-destination-alternate-hub&quot;. Airlines like Air Madagascar does this. Landing at an airport late in the night is another reason of nightstops. This is common with regional jets (737-ERJ-A32x...)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft operated by several airlines.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sometimes, you'll have aircraft operated by the owner some days in a week, and by another operator the remaining time. Take for example InterAir of South Africa. The aircraft is based at Johannesburg, and operates InterAir flights from and to JNB. But on Wednesday and Friday morning, the aircraft takes off from JNB as an InterAir flight, to Cotonou, and from there, it operates for AeroBenin to several destination in central Africa. The aircraft returns from Cotonou the Thursday and Saturday afternoon as regular InterAir flight. So don't be surprised to find a flight from JNB to Cotonou Wed and Fri morning, and their returning legs on Thu and Sat afternoon. That's common in Africa, South America and Asia. Many airlines like Blue Panorama, Lot Polish, EgyptAir (...) lend some of their aircraft to smaller airlines in the world on a week basis like this. The smaller airlines operate them on routes like &quot;hub-A-B-C-B-A-hub&quot; to use the aircraft as long as possible in the few hours/days.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So, those are only hints to understand how routes as selected and arranged. To enumerate all possible schemes, even a book won't suffice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to have much more aircraft than routes (when you have enough demand) or the inverse. An aircraft on the ground is an aircraft that costs money for nothing; so &quot;hub-X-hub&quot; flights are rarely the best way to operate an aircraft. Key words are &lt;strong&gt;&quot;demand&quot;&lt;/strong&gt;, &lt;strong&gt;&quot;costs&quot;&lt;/strong&gt;, &lt;strong&gt;&quot;profit&quot;&lt;/strong&gt;. To get factual datas to calculate those, you'll need parameters like aircraft performance, airframe availability, route statistics, crew/maintainance possibilities, security/safety, regulations/laws/authorizations... then compare and negociate the opening of the most profitable route with the less risks with the appropriate aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note : I'm no expert. I'm just an aviation enthusiast, mostly airliners of the 1960-today era.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastActivityDate="2014-10-12T14:29:21.987" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9077" PostTypeId="2" ParentId="9072" CreationDate="2014-10-12T15:08:39.367" Score="4" Body="&lt;p&gt;Piston engines will, in general, accept any medium-weight motor oil without complaining. While you should, also in general, use what the manufacturer specifies you can get away with quite a lot depending on the amount and your intentions. One litre low, moderate climate, short trip, planning on an oil change anyway? 7-11 brand 10W30 will be fine. Ferrying across Alaska in winter with 2 &quot;overnight&quot; stops? Better use the good stuff.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-12T15:08:39.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9078" PostTypeId="2" ParentId="9052" CreationDate="2014-10-12T15:19:25.570" Score="20" Body="&lt;p&gt;A few different reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Good pilots put the aircraft into a well-known (up) configuration after landing, so that the aircraft is ready for use on the next flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flaps down during taxi was a signal to the tower that the aircraft had been hijacked.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Take-off flaps (10 degrees on my airplane) and landing flaps (45 degrees), are nearly always different, so leaving the flaps down after landing at, say, 45, doesn't save any steps for departure. If the pilots forgets to set flaps before takeoff, some aircraft (like mine) will make it almost impossible to depart and climb out on full flaps because of the induced drag, &lt;a href=&quot;https://aviation.stackexchange.com/q/9183/1696&quot;&gt;while takeoff with no flaps is possible&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Prevent trucks and people from hitting the flaps while the airplane is parked, especially in the full-down (landing) configuration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some pilots employ the practice of &lt;a href=&quot;https://aviation.stackexchange.com/q/1189&quot;&gt;retracting the flaps during the rollout&lt;/a&gt; because it puts more weight on the wheels, reducing stopping distance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flaps down increases the amount of lift generated by the wing, so some aircraft might actually lift off the ground while parked with full flaps in high winds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-04-27T17:42:28.083" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9079" PostTypeId="2" ParentId="9045" CreationDate="2014-10-12T15:34:19.637" Score="2" Body="&lt;p&gt;There primary consideration in an emergency descent is to descend at the maximum allowable airspeed in the given configuration.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a jet, this is based on the &quot;barber pole&quot; on the airspeed indicator (which changes based on altitude). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the speedbrakes fail, you won't get the maximum descent rate, but you won't break the airplane by flying outside the aerodynamic envelope, either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a jet-type airspeed indicator with a red and white barber pole: &lt;a href=&quot;http://www.md80.it/cockpit/cockpit/captain/kuvat/asi.jpg&quot; rel=&quot;nofollow&quot;&gt;http://www.md80.it/cockpit/cockpit/captain/kuvat/asi.jpg&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I have a high-altitude endorsements as per 61.31(g)) &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-10-12T15:41:06.433" LastActivityDate="2014-10-12T15:41:06.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9080" PostTypeId="2" ParentId="9040" CreationDate="2014-10-12T16:20:24.450" Score="6" Body="&lt;p&gt;Here's what I do in a straight-in: fly it at cruise speed, and at 4 miles out, set power for final approach speed (you do know what that is, right? usually 15-17&quot; or 15-1700RPM in a light aircraft; also, some engines need to be cooled more slowly than going straight from cruise power to approach power). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft slows down, keep trimming the aircraft to stay on the VASI, and as you slow to Vfe for the different flap settings, bring those flaps in. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Full flaps should be in no lower than 500AGL for a stabilized approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can adjust the 4 miles to suit your preferences and conditions (slow or faster, depending on skills, wind, and traffic). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Full flaps when the runway is assured&quot; is a rule of thumb. More important is to not make any configuration changes (flaps, trim, gear, speed brakes) below 500AGL in VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you learn how to do this, you will fit in with lots of different kinds of traffic, and you won't have the Baron on downwind have to fly 5 miles out because you're doing 60 on long final. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This skill is also worth learning because it you will have a mastery of the landing process and get you out of the slavish &quot;do this, then do that, then do that&quot; type of flying&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good approaches make good landings!&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-10-13T14:37:12.770" LastActivityDate="2014-10-13T14:37:12.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9081" PostTypeId="2" ParentId="9072" CreationDate="2014-10-12T16:20:45.923" Score="16" Body="&lt;p&gt;By motor oil, I assume that you mean &lt;em&gt;automotive&lt;/em&gt; motor oil. In that case, it's a bad idea for a bunch of reasons. First, every airplane POH I've seen has specified that the oil must qualify to a standard - either MIL-L-6082 or MIL-L-22851 (though those have been superseded by an SAE standard). Modern automotive oil doesn't meet that standard, and therefore is effectively forbidden by the POH. More to the point, automotive oil is bad for aviation engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation and automotive engines work on the same basic principles, but many of the details are different.&lt;sup&gt;1&lt;/sup&gt; One significant difference is that aviation engines normally burn some oil as they run, while well-performing automobile engines burn little or none.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automotive oil contains a number of additives, such as detergents and wear inhibitors, intended for use where the oil doesn't burn off. Some of those additives do not burn completely, but instead stick around in the form of ash, where they can foul the engine and create deposits that lead to pre-ignition. That is why aviation oil is &lt;em&gt;ashless&lt;/em&gt; dispersant: it cleans the engine by dispersing combustion byproducts into the oil (to be removed on the next oil change), while being &lt;em&gt;ashless&lt;/em&gt; when burned. Lycoming considers it serious enough to put in an all-caps &quot;CAUTION&quot; section in their &lt;a href=&quot;http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201014M%20%2805-22-1995%29/Lubricating%20Oil%20Recommendations.pdf&quot;&gt;Lubricating Oil Recommendations&lt;/a&gt; document: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;UNDER&#xA;  NO CIRCUMSTANCES SHOULD AUTOMOTIVE OIL BE USED. THE USE OF AUTOMOTIVE&#xA;  LUBRICANTS IN TEXTRON LYCOMING ENGINES IS NOT RECOMMENDED BECAUSE ITS&#xA;  USE COULD CAUSE ENGINE FAILURE. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If all of that wasn't enough, use of an improper oil may void your engine warranty. In short: don't use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;References:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.avweb.com/news/maint/oil_myths_debunked_197096-1.html&quot;&gt;An editorial summary on Avweb&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ramaircraft.com/Maintenance-Tips/Oil-Recommendations.htm&quot;&gt;An aircraft engine overhauler's best practices&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.lycoming.com/Portals/0/techpublications/serviceinstructions/SI%201014M%20%2805-22-1995%29/Lubricating%20Oil%20Recommendations.pdf&quot;&gt;Lycoming's Lubricating Oil Recommendations&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;1) Note that I'm referring to air-cooled aviation engines that burn 100LL - made by, say, Lycoming or Continental. Rotaxes and new aero-diesels are different, and more like their respective automotive counterparts; in fact, Thielert engines are actually based on automotive diesels.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2014-10-12T17:12:45.573" LastActivityDate="2014-10-12T17:12:45.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9083" PostTypeId="2" ParentId="9045" CreationDate="2014-10-12T18:10:44.400" Score="14" Body="&lt;p&gt;The answer is actually quite simple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FOLLOW THE MANUFACTURES PROCEDURES.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft (I don't have a 737 flight manual handy) there is an altitude limitation if the spoilers are inop for just this scenario.  When the aircraft was certified, they needed to demonstrate an emergency descent (in the allowable time) without them, and that might not be possible from the certified ceiling. If that's the case in the 737, then descend to the max altitude with spoilers inop (assuming that you started above it).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is no altitude limitation and no special spoiler-inoperative emergency descent procedure (I have never seen one of those, but there's nothing to say that a manufacturer couldn't have one) then you simply fly the regular procedure without spoilers.  The manufacturer had to demonstrate this during certification and it must have been acceptable at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As rbp says, most of the time you fly Mmo/Vmo at idle power after you don the oxygen mask.  IF the flight manual/checklist says that you can put the gear down (some do) then you may, but I wouldn't otherwise.  I certainly wouldn't &lt;strong&gt;slow&lt;/strong&gt; to gear speed (unless the manufacturer says to....  Unlikely in a jet like this) because you are decreasing the drag by slowing, and taking time at altitude to do so.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-10-16T15:34:38.167" LastActivityDate="2014-10-16T15:34:38.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9084" PostTypeId="2" ParentId="1449" CreationDate="2014-10-12T18:44:00.380" Score="3" Body="&lt;p&gt;Full flaps can be used on take-off whenever it is called for in the POH, but I have never seen it in any of the 40 different aircraft I have flown. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft that I've flown (eg Cherokees and the Pilatus PC-12), there is an intermediate flap settings (about 25 degrees) which is used for short/soft field takeoffs because the extra lift from the downwash from the flaps helps the plane liftoff.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-10-12T18:44:00.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9085" PostTypeId="2" ParentId="8860" CreationDate="2014-10-12T20:55:12.833" Score="-2" Body="&lt;p&gt;What I'm going to say is my own opinion. I don't claim it's true, that's just my understanding of wake turbulences... I'm eager to learn, so feel free to correct me if I'm wrong :) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm assuming wake turbulence is moving air (airflow) caused by an aircraft flying ahead, wether airflow moving down, up, sideways or spiralling - I understand the pressure difference - Without going deep in particles motion (air molecules) I think you just have to consider &lt;strong&gt;four&lt;/strong&gt; things :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;your position behind a the leading aircraft : right behind its fuselage, right behind one of its wing tip, beyound its wingtip trail, from the axis of the leading aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;your distance behind the leading aircraft : a few feet just behind (without colliding with) or miles away ?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;wake size increases as you go far behind the aircraft producing the wake turbulence, but its strength decreases accordingly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The point 3 tells you where NOT to position your aircraft behind another. Especially at a (relative) location where the wake is &lt;em&gt;still&lt;/em&gt; powerfull, and its size is large enough to affect your controls surfaces and wing envelope, and send your aircraft in an uncomfortable motion, brutal gain or lost of lift, differential lift, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, right behind another aircraft, you &lt;em&gt;can&lt;/em&gt; fly without been affected (much) by the wake turbulence, because the wake size is not large enough to send your aircraft sideways, however, you still encounters slight turbulences, especially if you fly just right behind the wingtips. Worst situation is when you fly several hundreds feets behind the aircraft : large volume of strong spiralling airflow that you can't visualize. Miles aways, the airflow velocity is assumed to have dissipate enough because of its lost of strength due to expansion and air resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the wake turbulence of a Cessna is not the same of an A380. Weaker and smaller for a Cessna, that dissipates pretty quickly. This leads me to introduce point four :&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;4&quot;&gt;&#xA;&lt;li&gt;The size of the plane creating the wake, and the size of the following plane. Surprisingly, you can put an A350 right behind another A350, but you can't put a Cessna right behind an A350. This, because of the three points above : The Cessna will likely be affected by the slightest amount of airflow while the A350 wont much, because of surfaces size (wings/ailerons) The wake (especially the wingtip vortex) hasen't grow enough to hit the following A350 hard enough.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;However, that doesn't mean there aren't risks. Main risk in such close formation is vibration. Test pilots are trained to identify their origin and deal with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And also, I don't have a comparable aircraft in size, so I'll take a DC10, or a B52 : I think you can't put such earlier generation of aircraft right behind an A350 (or 787) because of Wing technology (this related to the question &lt;em&gt;&quot;does the A350 has something special ?&quot;&lt;/em&gt;) Old aircraft have much less flexible wings, that makes them really sensible to brutal airflow. I'm not a physicist, but more flexible wings better distribute the load factors along said wing, considerably reducing vibrations and fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's why wake turbulences are more dangerous at lower speed : the wake can grow enough to compromise the flight enveloppe of the following aircraft even at the tightest separation. That's why wake turbulence are a serious issue at lower altitudes where the moving airflow is really dense and affect surfaces greatly. Logically, wide wakes should dissipate more quickly in dense atmosphere, but the (tiny) spiralling vortex can last several minutes and is still very dangerous especially for smaller aircraft.&lt;br /&gt;&#xA;Fighter jets in airshow and flight formation :&lt;br /&gt;&#xA; a) They fly at high speed =&gt; not enough expansion to affect nearby followers&lt;br /&gt;&#xA; b) tandem formation requires lining up with leading aircraft =&gt; good distribution in differential lift.&lt;br /&gt;&#xA; c) in tandem formation, followers are usually below (rarely above) the preceding aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, a Cessna control surfaces (and flaps) are more sensible than the ones that equip a 777. Never get a Cessna below and behind a 777 in a five to ten minutes timespan unless you know where the wake turbulence path has drifted and/or landed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note : I'm not a pilot. I'm just interrested in how an aircraft flies. There are tons of documents out there about wake turbulences, wake vortices, stall schemas, etc. Some are contradictory, some are complementary. At a molecule level, the magic of an airflow looks like a perfect example of the theory of chaos. But the above is the summary of what I found here and there. That's no science, just opinion.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastActivityDate="2014-10-12T20:55:12.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9086" PostTypeId="2" ParentId="9071" CreationDate="2014-10-12T21:06:28.123" Score="1" Body="&lt;p&gt;That's right, the only case when the airport can't charge the airline is when the delay or extra time spent on the gate is airport management fault. Anyways everything depends on the country and the airport.&lt;/p&gt;&#xA;" OwnerUserId="3817" LastActivityDate="2014-10-12T21:06:28.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9088" PostTypeId="2" ParentId="2198" CreationDate="2014-10-13T04:17:47.457" Score="-2" Body="&lt;p&gt;Consider that radio line-of-sight horizon varies with altitude and transmission power.  I have not calculated the radio line-of-sight horizon from 30,000 to 35,000 feet but I imagine that it is staggering.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are Ham radio operators listening for distress calls twenty-four hours a day, around the world. A distress call accompanied by GPS coordinates would get immediate attention from anyone on the frequency. Ham satellites are another resource.&lt;/p&gt;&#xA;" OwnerUserId="3891" LastActivityDate="2014-10-13T04:17:47.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9089" PostTypeId="2" ParentId="3748" CreationDate="2014-10-13T07:58:55.443" Score="2" Body="&lt;p&gt;At the moment, planes travel at around mach .75 to .95; which is a tradeoff between speed and fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it is possible to produce faster airplanes, no one does, because significantly faster (=supersonic) planes are not allowed everywhere; apart from that, they need much more fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But to improve time, you don't have to consider using faster planes on some legs, you have to consider the whole trip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which may be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;90 minutes from manhattan to airport during rush hour&lt;/li&gt;&#xA;&lt;li&gt;Check in, security check: 90 minutes&lt;/li&gt;&#xA;&lt;li&gt;Six hours on a 747, 3 on a Concorde.&lt;/li&gt;&#xA;&lt;li&gt;90 minutes waiting for the connecting flight (if you are lucky).&lt;/li&gt;&#xA;&lt;li&gt;Three hours on a 737.&lt;/li&gt;&#xA;&lt;li&gt;Half an hour by cab to your Oslo office.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Which makes your whole trip 14 hours on a normal plane, or 11 hours if you take Concorde, doubling(?) the price. I guess that heli transfers from and to the airports would be better investments than a seat on Concorde, if your company has helipads on the roof.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall trip times are why Boeing decided to not supersize their planes even more, and opt for more direct connections instead:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;90 minutes from manhattan to airport during rush hour&lt;/li&gt;&#xA;&lt;li&gt;Check in, security check: 90 minutes&lt;/li&gt;&#xA;&lt;li&gt;7.5 hours on a 787&lt;/li&gt;&#xA;&lt;li&gt;Half an hour by cab to your Oslo office.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And voilà, you are down to 11 hours, without the need for fancy supersonic planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way: While flying all-Economy is what some low-fare airlines do for a living; no one was ever successful in trying scheduled all-First flights. First is mostly combined with Flex. So, while First is a good thing on top, Economy is the bread-and-butter business which attracts the Flex-First bookers, because Economy is what allows the airline to do seven trips a day and still have a spare seat for the VIP on whichever connection he chooses.&lt;/p&gt;&#xA;" OwnerUserId="1745" LastActivityDate="2014-10-13T07:58:55.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9090" PostTypeId="2" ParentId="9071" CreationDate="2014-10-13T08:23:30.490" Score="5" Body="&lt;p&gt;The correct answer may differ for each pair (airline, airport) and can be found in the contract that they mutually agreed upon. Such contracts are mostly seen as a business secret, and most of their contents are not known to the general public.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, both parties agree to do their best to keep everything working during every weather. Which means that there has to be enough equipment to clear a runway really quick, such that these &quot;penalties&quot; are &quot;background noise&quot; in the overall bill, even compared to the penalties caused by other reasons. The airport may decide not to bill the airline most of these penalties, as long as the airline won't try to bill every loss caused by the airport's fault. As a rule of thumb, you don't upset your business partners like that over peanuts, more so if claims go both ways. They may even have agreed on how many minutes delay won't be billed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet, this partnership may be put to the test when one of the partners is seen as cutting cost at the expense of the other, or when one really unexpected condition occurs (like that volcano on Iceland, which disrupted air traffic in central Europe for two weeks or more).&lt;/p&gt;&#xA;" OwnerUserId="1745" LastActivityDate="2014-10-13T08:23:30.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9091" PostTypeId="2" ParentId="9074" CreationDate="2014-10-13T08:51:42.100" Score="2" Body="&lt;p&gt;The flight plan can be changed by the minute, as long as the two governments and the two airports and the airline agree on this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it seems like the government pays the airline to just take off whenever they are allowed to, take the airline out of the equation.&#xA;Likewise for the airports, since they are either state-operated or have a concession which states that they have to assist in lawful deportations, emergencies or state affairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This keeps two governments in, which have to agree on a time and the who-pays-whom-how-much for the deportation to really take place. In fact, I think this is the only reason why the plane is not yet airborne - because of two governments playing their diplomacy games.&lt;/p&gt;&#xA;" OwnerUserId="1745" LastActivityDate="2014-10-13T08:51:42.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9092" PostTypeId="2" ParentId="9063" CreationDate="2014-10-13T09:16:49.840" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What happens in the control room?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aborting a take-off at high speed is dangerous, even if the aircraft is travelling below V1. If the aircraft is already rolling, the controller will make a quick decision whether the situation justifies an aborted take-off. For example, if there is traffic infringing the runway and a crash is imminent the controller would attempt to stop the aircraft. If an aircraft is attempting to take-off from a taxiway in snowy conditions it might be safer to just let him take-off unless there is other traffic on the taxiway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft hasn't started rolling the decision is of course easily made. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What does the ATC do and how does he/she make sure pilots understand&#xA;  the cancellation?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Using standard phraseology is the best way of making sure the message comes across, especially in international aviation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is not yet rolling, the proper ICAO phraseology is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; Big Jet 345 hold position, Cancel take&#xA;  - off, I say again cancel take&#xA;  - off (due to vehicle on the runway)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Big Jet:&lt;/strong&gt; Holding, Big Jet 345&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the aircraft already started rolling the controller would say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Tower:&lt;/strong&gt; Big Jet 345 stop immediately, (Big Jet 345 stop immediately )!&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Big Jet:&lt;/strong&gt; Stopping, Big Jet 345&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No immediate verbal reply is to be expected as the flight crew have other things to care about at that moment. The effect of their actions should be clearly visible from the tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;/p&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How do the pilots in the aircraft taking off respond? Are they trained for this scenario?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The crew will assess whether they can stop safely. Below V1, they will probably abort the take-off, above probably not. The final judgement is made by the captain. He might reason that it is safer to get airborne and pass the infringing traffic overhead than running into it at full brakes. They are trained for aborted take-offs, but since there are so many non-standard situations the final decision is made on the basis of a mix of training and expert judgement. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is a takeoff cancelled even after V1?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since ATC does not know when the aircraft passes V1, a controller might attempt to cancel the takeoff after V1. The flight crew will only attempt to cancel the take-off after V1 if it is clear that there is no way the aircraft can become - and stay - airborne safely. In such a case it becomes damage control rather than damage prevention. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-13T09:16:49.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9094" PostTypeId="1" AcceptedAnswerId="9107" CreationDate="2014-10-13T11:19:54.707" Score="14" ViewCount="9102" Body="&lt;p&gt;To make comparison easy, let us take the example of B737 and A320, both similar aircrafts with retractable landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As seen on the photo below, the B737 doesn't have gear doors for the wheels, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aQyH9.jpg&quot; alt=&quot;737 Underside View&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but the A320 does&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p3WY4.jpg&quot; alt=&quot;A320 Planform View&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, Boeing and Airbus made different choices for the same feature and both seem reasonable. Both aircraft models are well accepted by the airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages and disadvantages of both designs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: I put links to other images where both aircraft are retracting landing gear after take off. The difference is obvious as we can see the landing gear doors operated for the &lt;a href=&quot;http://www.airliners.net/photo/CSA---Czech/Airbus-A320-214/1342671/&amp;amp;sid=0dcd645676e4024c412c6f49c108d858&quot; rel=&quot;noreferrer&quot;&gt;A320&lt;/a&gt; and no doors for the &lt;a href=&quot;http://www.airliners.net/photo/Transavia-Airlines/Boeing-737-8K2/1340730/&amp;amp;sid=6144b6515e119662f895aaf02e1e7f5a&quot; rel=&quot;noreferrer&quot;&gt;B737&lt;/a&gt;'s wheel.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="11411" LastEditDate="2015-09-29T12:25:13.200" LastActivityDate="2017-09-21T03:10:07.900" Title="What are the advantages and disadvantages of having landing gear doors?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;landing-gear&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9095" PostTypeId="2" ParentId="9094" CreationDate="2014-10-13T13:00:48.503" Score="4" Body="&lt;p&gt;Doors add weight and complexity to the aircraft, and need to be inspected and maintained. But doors also provide a smooth surface for the air to travel over, so they would have less drag. The 737 does have doors, but for the gear struts, but the wheels lay fairly flat against the fuselage, so drag is minimized. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-10-13T13:00:48.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9096" PostTypeId="1" AcceptedAnswerId="9099" CreationDate="2014-10-13T13:22:49.023" Score="31" ViewCount="8642" Body="&lt;p&gt;I speak of passenger aircraft that can be found on large airports.&#xA;The left side is used by passengers (and the crew) to embark/disembark (see the &lt;a href=&quot;https://commons.wikimedia.org/wiki/Category:Jet_bridges&quot; rel=&quot;nofollow noreferrer&quot;&gt;position of jet bridges&lt;/a&gt;) and the other side to embark/disembark the rest (e.g. food).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do we always use the left side for passengers? What prevents an airport from deciding to use the other side?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this is an historical decision (e.g. one day in the past an aircraft builder decided passenger should use the left side, then majors airports were built accordingly and thus new aircraft were built accordingly and thus new airports were built accordingly), is it possible and reasonnable to build a jet bridge made to operate on the right side of an aircraft and then use the right side for passengers and the left side for the rest?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3386" LastEditDate="2018-01-17T00:28:26.583" LastActivityDate="2018-01-17T00:28:26.583" Title="Why do passenger embark on the left side of an aircraft?" Tags="&lt;passenger&gt;&lt;airport-design&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9097" PostTypeId="2" ParentId="9096" CreationDate="2014-10-13T13:51:04.507" Score="2" Body="&lt;p&gt;I expect it comes from the fact that aircraft development started in countries that drive on the right side of the road. The pilot sat on the left because, well, that's where drivers sit. The early airliners would park with the &quot;terminal&quot; / shed / tent / hole in the fence on the left side so the pilot could steer without hitting anything (better view out the window), the pilot could climb out his door and open the rear door to unload the mail without walking around to the other side of the plane so that's where the cargo handlers / trucks / horses would wait.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remove the front door on larger aircraft, replace it with a rear door closer to the ground. You still put it on the left for compatibility with all the other stuff flying. Fast forward to the modern day and we find that we have to pick one side or the other, &lt;em&gt;everything&lt;/em&gt; has a left door, some have doors on both sides, so....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've considered that monsters like the A380 should use jetways on both sides but making a jetway reversible is mechanically very complex. Economics kick in here as the largest planes are not used for short routes where a 30-minute turnaround matters. The cost of dual-side jetways doesn't have a reasonable payoff.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-13T13:51:04.507" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9098" PostTypeId="1" CreationDate="2014-10-13T14:19:31.087" Score="6" ViewCount="2776" Body="&lt;p&gt;What would happen if I perform an emergency landing at an Air Force airfield?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would they send fighters planes to intercept me?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would they arrest me? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would they detain my aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="97" LastEditDate="2014-10-29T19:56:15.517" LastActivityDate="2014-10-29T19:56:15.517" Title="Emergency landing at Air Force airfield" Tags="&lt;faa-regulations&gt;&lt;military&gt;&lt;usa&gt;&lt;flight-interception&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ClosedDate="2014-10-13T15:52:31.940" ContentLicense="CC BY-SA 3.0" />
  <row Id="9099" PostTypeId="2" ParentId="9096" CreationDate="2014-10-13T14:40:17.660" Score="43" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why do passenger embark on the left side of an aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Because the cavewoman who invented the log-canoe was right-handed?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note: I arrived at this answer by looking at a kind of etymology of the terms starboard &amp;amp; port but that's incidental. The answer to this question happened to be contained in an answer to a rather different question. Some groups of aviators may have dropped the archaic terms while still being subject to a continuation of an archaic habit/convention.&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;People get on the left side of a jet airplane because Vikings (etc) steered their wooden boats with a steering board (hence starboard?) held in their dominant right-hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it was inconvenient to have your steering apparatus wedged against a quayside (or earthen bank) they docked at the &lt;strong&gt;port&lt;/strong&gt; along their left side and therefore loaded and unloaded on the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9096/why-do-passenger-embark-on-the-left-side-of-an-aircraft#comment16669_9096&quot;&gt;Farhan's comment&lt;/a&gt; leads you to &lt;a href=&quot;https://english.stackexchange.com/questions/112112/does-the-use-of-port-for-one-side-of-ship-relate-to-the-word-port-meaning-ha/112115#112115&quot;&gt;this answer&lt;/a&gt; in English.se which I reproduce here for convenience&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Excerpt from &lt;a href=&quot;http://www.history.navy.mil/trivia/trivia03.htm&quot; rel=&quot;noreferrer&quot;&gt;trivia on the Navy website&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Port and starboard&lt;/strong&gt; Port and starboard are shipboard terms for left and&#xA;  right, respectively. Confusing those two could cause a ship wreck. In&#xA;  Old England, the starboard was the steering paddle or rudder, and&#xA;  ships were always steered from the right side on the back of the&#xA;  vessel. Larboard referred to the left side, the side on which the ship&#xA;  was loaded. So how did larboard become port? Shouted over the noise of&#xA;  the wind and the waves, larboard and starboard sounded too much alike.&#xA;  The word port means the opening in the &quot;left&quot; side of the ship from&#xA;  which cargo was unloaded. Sailors eventually started using the term to&#xA;  refer to that side of the ship. Use of the term &quot;port&quot; was officially&#xA;  adopted by the U.S. Navy by General Order, 18 February 1846.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's a historical convention, many arbitrary choices are of this sort. Pioneers of a new form of transport adopt the terms (port, startboard) and habits of more ancient forms of transport.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ironically, since aircraft became able to carry substantial non-human cargo, the cargo entry has moved to the other side to reduce the chances of crushing the human cargo with the non-human cargo. Presumably also because having lots of large holes all in one side may be structurally disadvantageous.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-10-14T14:18:00.590" CommentCount="7" CommunityOwnedDate="2014-10-13T14:40:17.660" ContentLicense="CC BY-SA 3.0" />
  <row Id="9100" PostTypeId="2" ParentId="9098" CreationDate="2014-10-13T14:40:54.393" Score="4" Body="&lt;p&gt;There are some bases that are joint-use anyway, and in that case, it would be almost exactly like an emergency landing at a civilian field. Then most bases will do little if you are truly an emergency. The times this would come into play are sensitive bases such as Nellis AFB or Groom Lake, or bases that have significant national security interests, such as Andrews AFB, or potentially a base with nuclear bombers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these cases, you would probably get a fighter escort if you reported intentions soon enough or entered restricted airspace. Most bases will not provide a fighter escort, as there is little they can do to help, and you should not be a threat to anything from the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you declared an emergency and nothing was actually wrong, you would almost certainly be arrested. If there was an actual emergency, you would probably be detained at a sensitive base, but at most bases they would just keep you confined to unsensitive visitor's areas. &lt;a href=&quot;http://www.travis.af.mil/news/story.asp?id=123403610&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; is an incident where the pilot was forced to land at Travis AFB (which only has C-5, C-17, and KC-10 aircraft). The pilot followed emergency procedures and everything turned out well. But the report notes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Had he not made contact with RAPCON, security forces would have to respond as if the aircraft was hostile,&quot; Wilson said. &quot;His proper communication allowed us to clear the area for him and notify the appropriate agencies.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As your aircraft is not flyable at the moment, it would have to stay there until it was repaired, but in most cases you should be able to fly it out after it was fixed. In a sensitive area, I have heard reports of airplanes being disassembled and shipped off the base, but nothing concrete about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, at most of the most prohibited areas the prohibited airfield is rarely going to be you best option (e.g. it would be unlikely for Groom Lake to be your only option, unless you were snooping around the edges, which they would not take kindly to). But just remember - in an emergency, you are in control until your plane is on the ground. So make &#xA;the conservative decision and land safely. If it is an emergency, and you weren't pushing limits before the emergency, the most you should get is a stern talking-to and a short detainment.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2014-10-13T15:37:40.613" LastActivityDate="2014-10-13T15:37:40.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9101" PostTypeId="1" CreationDate="2014-10-13T15:25:53.097" Score="24" ViewCount="3035" Body="&lt;p&gt;Does it make sense towing airplanes to the head of airstrip by electric means, whether internal or external?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxiing from the gate to the runway on jet power seems like a waste of fuel. Is it possible and it would make sense to tow the airplane to the start of take-off run by a motorized towing unit or perhaps with electric motors in the airplane's landing gear? Was this ever tested or assessed?&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2018-02-26T09:44:55.183" LastActivityDate="2018-02-26T09:44:55.183" Title="Does it make sense towing airplanes to the head of airstrip by external (eg electric) means?" Tags="&lt;taxiing&gt;&lt;electric-engine&gt;&lt;towing&gt;" AnswerCount="5" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9103" PostTypeId="2" ParentId="9101" CreationDate="2014-10-13T15:58:36.420" Score="26" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Was [towing unit or motors in landing gear] ever tested or assessed?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Yes.&lt;/p&gt;&#xA;&lt;h2&gt;2014 Main Gear&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Using the Auxiliary Power Unit (APU) generator to power motors on the main wheels, the EGTS taxiing system allows aircraft to push back without a tug and then taxi without requiring the use of the main aircraft engines. One wheel on each main gear is equipped with an electric motor to drive the aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.greentaxiing.com/&quot; rel=&quot;noreferrer&quot;&gt;EGTS&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Airbus signs MoU with Honeywell and Safran to develop electric taxiing solution for the A320 Family&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-signs-mou-with-honeywell-and-safran-to-develop-electric-taxiing-solution-for-the-a320-family/&quot; rel=&quot;noreferrer&quot;&gt;Airbus press release&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Lufthansa Technik has proven with a technology demonstrator that aircraft can be driven on ground by electric motors.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.lufthansa-technik.com/etaxi&quot; rel=&quot;noreferrer&quot;&gt;Lufthansa Technik&lt;/a&gt; (with video)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;2015 Towing Unit&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;As of 2015 Taxibot, a semi-robotic towbarless tractor which meets and connects to aircraft, is the only alternative taxiing system certified and currently in use by airlines in the market.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/TaxiBot&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;2016 Nose Gear&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Honeywell and Safran have pulled the plug on their jointly conceived electric taxiing system, while rival developer WheelTug aims to enter service with its system in 2018.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;After thorough market analysis&amp;quot;, the US supplier says, the two partners &amp;quot;agreed to stop work on the Electric Green Taxiing System due to dramatically lower oil prices and the current aviation industry's economic environment&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;EGTS had been scheduled to enter service this year, with Honeywell and Safran having planned to produce a system for line- and retrofit on A320-family and Boeing 737 jets.&lt;/p&gt;&#xA;&lt;p&gt;Meanwhile, Gibraltar-headquartered WheelTug plans to enter service with its nose gear-mounted electric drive system in 2018.&#xA;... initially on 737s and, at a later stage, on A320-family ...&#xA;Neither Airbus nor Boeing are supporting the programme&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.flightglobal.com/news/articles/farnborough-honeywell-and-safran-halt-electric-tax-427400/&quot; rel=&quot;noreferrer&quot;&gt;FlightGlobal&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-02-07T10:36:16.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9104" PostTypeId="2" ParentId="9056" CreationDate="2014-10-13T16:03:56.070" Score="3" Body="&lt;p&gt;I'm not a pilot. I did attempt to get a parachute license, but stopped after a couple of jumps. I jumped at two different drop zones. (And I'm from Sweden) I just thought I'd offer a view from the other side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the DZs where I jumped, the pilot always talked to ATC before takeoff, so I would assume that ATC will know of any parachute activity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The parachutists will fall, so if you can stay above the plane that will drop them, you'll be fine. Where I jumped, 4000 m was highest allowed altitude without oxygen, so no one jumped from higher than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The parachutists will want to land at or very close to their field. During the freefall part, they don't really drift with the wind. Chutes will typically be opened at about 1000 m, and from that altitude, they will drift significantly with the wind. Thus, they will be dropped upwind, and will typically not move very far downwind of the field, especially not at high altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in order of simplest/safest:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Fly above them&lt;/li&gt;&#xA;&lt;li&gt;Fly downwind of their landing spot&lt;/li&gt;&#xA;&lt;li&gt;If you need to fly close to their field, the higher up you can be, the better.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This should perhaps be taken with a few grains of salt, but hopefully others can chime in if I've said something incredibly stupid. :)&lt;/p&gt;&#xA;" OwnerUserId="3900" LastActivityDate="2014-10-13T16:03:56.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9105" PostTypeId="2" ParentId="8270" CreationDate="2014-10-13T17:01:36.767" Score="6" Body="&lt;p&gt;As Peter Kämpf mentioned, Rolls Royce is unique in that they don't just sell the engines to customers anymore. Rolls Royce will charge by engine time, and take responsibility for maintenace costs. This provides incentive for RR to make their engines as reliable as possible, but it also allows them to choose to keep the maintenance work in-house.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air France KLM also prefers to keep their maintenance in-house. They have been &lt;a href=&quot;http://www.mro-network.com/analysis/2013/07/no-afterthought-rolls-royce-and-aftermarket/1345&quot;&gt;negotiating&lt;/a&gt; with RR to be able to perform maintenance themselves on the Trent XWB engines on their on-order A350 aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other manufacturers like &lt;a href=&quot;http://www.cfmaeroengines.com/services/maintenance&quot;&gt;CFM&lt;/a&gt;, &lt;a href=&quot;http://www.geaviation.com/commercial/services/&quot;&gt;GE&lt;/a&gt;, and &lt;a href=&quot;http://www.pw.utc.com/Parts_and_Services&quot;&gt;PW&lt;/a&gt; do not operate in the same way. These companies will sell the engines, and the customer gets to choose where to have maintenance performed. All three companies offer their own programs, but they compete against &lt;a href=&quot;http://www.deltatechops.com/mro-capabilities/view/category/cfm56&quot;&gt;third&lt;/a&gt; &lt;a href=&quot;http://www.jetairsupport.com/&quot;&gt;party&lt;/a&gt; &lt;a href=&quot;http://www.ctsengines.com/&quot;&gt;services&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Despite not sharing the same strategy for promoting those programs, all of these companies receive substantial revenue from their OEM maintenance programs.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-13T17:01:36.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9106" PostTypeId="2" ParentId="9101" CreationDate="2014-10-13T17:01:58.730" Score="15" Body="&lt;p&gt;Variations on this kind of scheme and designs are currently being worked on. From what I remember, using electric motors are still pretty expensive, and also you're using them for a very short time frame, such that you're lugging around extra weight that is useful for a tiny portion of time(aka more fuel burn). Tugs of various sorts have been used at various places as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also consider that various engines need time to warm up before applying full throttle, sometimes just a few seconds, others a few minutes.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-10-13T17:01:58.730" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9107" PostTypeId="2" ParentId="9094" CreationDate="2014-10-13T17:44:27.703" Score="16" Body="&lt;p&gt;&lt;strong&gt;Benefits of gear doors&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With gear doors, there are fewer constraints on the retracted gear position. This is especially important in larger aircraft with larger and more complex landing gear. It doesn't need to be flush with fuselage or streamlined (737 also uses &lt;a href=&quot;https://c1.staticflickr.com/5/4008/4331431885_1bb49a8edd.jpg&quot;&gt;hubcaps&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;The gear doors provide a good aerodynamic surface&lt;/li&gt;&#xA;&lt;li&gt;Opening to gear bay can be larger and easier to access&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Drawbacks of gear doors&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Extra weight for the door and the mechanisms&lt;/li&gt;&#xA;&lt;li&gt;Extra complexity of opening another door (possibility for &lt;a href=&quot;http://avherald.com/h?article=469338e0&quot;&gt;things to go wrong&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-14T14:21:21.050" LastActivityDate="2014-10-14T14:21:21.050" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9108" PostTypeId="2" ParentId="2021" CreationDate="2014-10-13T18:25:37.337" Score="8" Body="&lt;p&gt;Cell networks require that cell towers be able to distinguish between signals coming from phones which are within the zones served by the towers, and those coming from phones in more distant zones.  There are nowhere near enough radio frequencies or time slices to allow every zone in the US to have its own combination of frequency and time slice.  In general, however, since the amount of signal received from a phone that's transmitting at a particular power level will drop off in proportion to the square of the distance, arranging zones so that the closest phone outside of a zone that will use a particular frequency/time-slice combination will never be less than be 3 times as far away as the furthest phone within the zone will generally make it possible for towers to receive the signals from phones within their service zones without too much interference from phones in other zones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a phone which is on a plane, 30,000 feet above the surface, transmits a signal which is loud enough to be heard by a tower serving a zone directly below, that same signal is likely to be received almost as well by towers for quite a ways around, some of which might have been expecting to use the same frequency and time slice to serve their own zones.  A cell network might be able to recognize the situation and assign frequencies and time slices in such a way as to avoid interference, but a single phone call from a plane might tie up ground-level bandwidth resources in multiple zones which, but for that call from the air, could each have used those resources to handle a separate call.&lt;/p&gt;&#xA;" OwnerUserId="973" LastEditorUserId="753" LastEditDate="2016-12-29T15:11:19.090" LastActivityDate="2016-12-29T15:11:19.090" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9110" PostTypeId="2" ParentId="9096" CreationDate="2014-10-13T18:32:32.757" Score="1" Body="&lt;p&gt;The earliest air forces in Europe derived from cavalry regiments, flying was expensive and the preserve of the rich - as was the cavalry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because a right handed horseman carries his sword on the left, he will mount a horse from it's left side - so he throws his right leg over the mount. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why the pilot in command sits in the left seat and enters from the left side of the aeroplane. When passengers started entering through a door the same tradition continued. &lt;/p&gt;&#xA;" OwnerUserId="1576" LastActivityDate="2014-10-13T18:32:32.757" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9111" PostTypeId="2" ParentId="9101" CreationDate="2014-10-13T18:39:46.297" Score="7" Body="&lt;p&gt;Along with fitting electric motors to allow push-back without a tug and more efficient taxiing, &lt;a href=&quot;http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/taxibot-set-to-usher-in-a-new-era-of-airport-taxiing/&quot; rel=&quot;nofollow&quot;&gt;there is a plan to use tugs controlled by the aircraft for the taxi.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="1696" LastEditDate="2016-07-06T22:01:15.557" LastActivityDate="2016-07-06T22:01:15.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9112" PostTypeId="1" AcceptedAnswerId="9113" CreationDate="2014-10-13T19:27:25.157" Score="23" ViewCount="5355" Body="&lt;p&gt;I just read an &lt;a href=&quot;http://www.businesstraveller.com/news/the-big-picture-ba-unveils-dove-livery&quot;&gt;article&lt;/a&gt; (published in 2012) telling the special livery for British airways' A320 to celebrate the Olympics game is made to last one year. I assume this mean those aircraft are painted once per year because painting is not free and thus it is reasonnable to change the livery only when painting is already schedule. But because this is a special livery, it may last less than other painting. As this is only assumptions, my question is the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How often is an Airbus or a Boeing painted (even without changing the livery)? Does it significally change from on airline to another? Does a special livery change this frequency?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="7532" LastEditDate="2015-12-16T00:44:55.020" LastActivityDate="2015-12-18T09:59:12.283" Title="How often is a passenger jet aircraft painted?" Tags="&lt;airliner&gt;&lt;aircraft-maintenance&gt;&lt;livery&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9113" PostTypeId="2" ParentId="9112" CreationDate="2014-10-13T20:05:19.343" Score="16" Body="&lt;p&gt;As always, it depends. From what I've seen and read, it's usually redone every 5-10 years. This can vary on various factors from paintshop availability, to new color scheme rollout, to deterioration of the previous one due to bad painting, to quality of the paint used. Sometimes, special liveries are just an aviation specific sticker that's put onto an aircraft, other times it's fully painted onto the aircraft, just depending on the airline, the planned length of time for it to be special, and any other considerations.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-10-13T20:05:19.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9114" PostTypeId="1" CreationDate="2014-10-13T21:19:05.037" Score="19" ViewCount="13888" Body="&lt;p&gt;Why is 100LL so much more expensive than gasoline for cars?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I get the fact that it's 100LL, instead of 87, 91, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example (as of now, 13 Oct 14), the 91 unleaded gas at my local gas station is 3.41USD, and the 100LL at my local airport is 5.49USD (for the self serve).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the reason for the huge increase in price between car and aviation gas?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="15311" LastEditDate="2019-04-04T10:51:19.290" LastActivityDate="2019-04-04T16:23:37.120" Title="Why is AVGAS so much more expensive than car gas?" Tags="&lt;fuel&gt;&lt;cost&gt;&lt;avgas&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9115" PostTypeId="2" ParentId="9114" CreationDate="2014-10-13T21:53:10.373" Score="10" Body="&lt;p&gt;The distillation and refining process for 100LL is more expensive than the process for 91 unleaded. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;100LL has a high octane index, and is treated to be less volatile (in particular at high altitudes). 100LL is also perfectly dry in order to prevent icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, 100LL is produced in smaller quantities than car fuel, so economies of scale are also a factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, due to the high price of aviation fuel, certain low-powered engines can be certified to fly with the same gas you put in your car. &lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-10-13T21:53:10.373" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9116" PostTypeId="1" AcceptedAnswerId="9118" CreationDate="2014-10-14T00:06:57.870" Score="87" ViewCount="34160" Body="&lt;p&gt;As seen in multiple pictures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, this one, it appears the aircraft is spraying copious amounts of fuel into the exhaust!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surely this provides no thrust, not in the way an afterburner (which the F-111 has!) does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it perhaps as an alternative to flares for anti IR missiles? It seems logical, but I don't think so, because I've seen it on takeoff too!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tzTeN.jpg&quot; alt=&quot;From this image, it looks like the aircraft is spraying COPIOUS amounts of fuel into the exhaust!&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At any rate, it is QUITE badass!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Io6nN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: &lt;a href=&quot;https://www.youtube.com/watch?v=WpPEdOMSIgQ&quot;&gt;YouTube video!&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;EDIT: Can any other aircraft perform this?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="15311" LastEditDate="2019-04-04T10:51:12.147" LastActivityDate="2019-07-28T23:38:55.663" Title="Why does the F-111 sometimes squirt a giant fire plume behind it? (NOT afterburners!)" Tags="&lt;military&gt;&lt;fuel&gt;&lt;fuel-dumping&gt;&lt;f-111&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9117" PostTypeId="1" AcceptedAnswerId="9129" CreationDate="2014-10-14T00:47:25.023" Score="12" ViewCount="1531" Body="&lt;p&gt;I just got a new FAA medical certificate, and I accidentally put down that my hair color is blonde when in reality it is dark brown. Also, my hair is listed as brown on my pilot certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I bleach my hair in the summer, which makes it blonde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would such a small detail cause any sort of trouble? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="14661" LastEditDate="2016-05-29T08:32:39.700" LastActivityDate="2016-05-29T08:32:39.700" Title="Can having an incorrect hair color on my FAA medical certificate get me in trouble?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9118" PostTypeId="2" ParentId="9116" CreationDate="2014-10-14T00:54:37.757" Score="107" Body="&lt;p&gt;The F-111 has, like many aircraft, a fuel dump port so it can get rid of a lot of heavy fuel rather quickly. Most aircraft have the dump ports on the wings, the F-111 designers put it in the tail between the engines. End result is if you dump fuel and briefly light the afterburner you will ignite the liquid fuel in your wake creating a rather spectacular trail of fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerodynamically it's completely useless, financially it's very expensive, you'd only do it in combat if you were suicidal as it greatly increases your IR signature right where you don't want it, but at an airshow it does look totally badass, especially as the afterburner is adding a lot of noise at the same time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would expect any pilot who does a dump-and-burn outside of an airshow (or an emergency) will have his own tail set on fire by the air wing's commanding officer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SR-71 had a similar issue - it leaked like a sieve on the ground. Rotating for takeoff would occasionally set fire to the JP-7 on the runway leaving a burning trail behind it much like the Road Runner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Reply to the video:&lt;/strong&gt;&#xA;watch the takeoff section carefully. You can clearly see the afterburners come on before the fuel dump starts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Reply to about half the comments:&lt;/strong&gt;&#xA;Highly unlikely they designed it to do this. The F-111 was one of the earlier swing-wing planes, that meant that you can't put much on the wings. And as the bigger tank is in the fuselage anyway, someone would have looked at the space between the engines and thought it was just right for a dump pipe. The flame effect was probably discovered later.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-10-16T08:38:38.887" LastActivityDate="2014-10-16T08:38:38.887" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="9120" PostTypeId="2" ParentId="9116" CreationDate="2014-10-14T10:06:45.713" Score="68" Body="&lt;p&gt;There was at least one occasion when the dump-and-burn was used in combat. During the 1986 attack on &lt;a href=&quot;http://muse.jhu.edu/journals/cws/summary/v006/6.3alexander.html&quot;&gt;Libya&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the U.S. pilots, desperate for fuel, jostling with one another in the air to get access to aerial refueling tankers. Unable to break radio silence, they could not locate the giant KC-10A Extenders and KC-135R Stratotankers that would keep them from crashing into the sea. An F-111 pilot finally solved the problem by doing a &quot;little torching,&quot; as he dumped some fuel and ignited it with his afterburner, &quot;creating a huge explosion that both lit up the sky and pointed the direction to the tanker&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3908" LastActivityDate="2014-10-14T10:06:45.713" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9121" PostTypeId="2" ParentId="9114" CreationDate="2014-10-14T10:17:26.033" Score="33" Body="&lt;p&gt;The LL of 100LL stands for Low Lead as it has tetra-ethyl lead added as a detonation inhibitor for high-performance engines. Despite the &quot;low&quot; moniker there actually is a lot of it in there, and it's toxic. This fuel is expensive for a number of reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The lead itself is expensive&lt;/li&gt;&#xA;&lt;li&gt;The lead additive means that a refinery must shut down and clean the lead before producing other fuels, this means more refinery time and therefore more costs&lt;/li&gt;&#xA;&lt;li&gt;Lead in fuel cannot be allowed to contaminate other fuels so you cannot pipeline leaded fuel. It has to be transported in containers, adding to shipping costs&lt;/li&gt;&#xA;&lt;li&gt;There are extra controls around the lead in many parts of the world, namely storage requirements and paperwork, all which costs&lt;/li&gt;&#xA;&lt;li&gt;100LL fuel has many more &quot;aromatic&quot; hydrocarbons than mogas (auto fuel) in order to increase the octane levels and prevent fuel from vaporizing in your lines at high altitude. It's much higher grade, so it costs more&lt;/li&gt;&#xA;&lt;li&gt;It's a specialist fuel made in much less quantities than other fuels, so a premium is added to ensure a profit&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the Avgas is taxed less than Mogas in most places. It would cost even more if it were taxed the same! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Efforts are underway to come up with a 100LL replacement that will work the same in all engines and situations, which is a hard problem to solve. Whatever fuel they come up with, while having no lead, will still likely be more expensive than mogas just because of the more expensive hydrocarbon mix and the specialist nature of the fuel.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="938" LastEditDate="2015-05-23T23:13:55.590" LastActivityDate="2015-05-23T23:13:55.590" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9122" PostTypeId="1" AcceptedAnswerId="9124" CreationDate="2014-10-14T12:07:11.350" Score="22" ViewCount="7690" Body="&lt;p&gt;When I first time heard this &quot;legend&quot; I couldn't believe it. I was really surprised, if not shocked, to actually find row 13 missing on my next passenger flight. (I believe it was a Boeing 737.) Is this really due to superstition about the 13th row? Was it so hard to push aircraft producers to renumber all other seat rows?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that people can be absurd about their superstitions. But realistically, the odds that a passenger airplane will crash are minimal. And should it really crash, chances that you'll survive due to being seated in row 12 or 14, as opposed to 13, must be below statistical error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find it very difficult to believe that people would choose not to fly simply due to superstition about being seated in row 13. Is there a more rational explanation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt; (after Patrick's answer): &lt;em&gt;I don't know, if I expressed myself enough clearly. I don't think, that people are dumb, because the're worried about number 13&lt;/em&gt;. &lt;em&gt;I rather think, that thinking, that row 13 is unlucky&lt;/em&gt;, specifically on airplanes &lt;em&gt;(where, in case case of crash&lt;/em&gt; all &lt;em&gt;seats mostly are equally unlucky) is a bit weird.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="3230" LastEditDate="2014-10-15T07:01:11.683" LastActivityDate="2019-10-16T07:01:01.713" Title="Is triskaedekiphobia (fear of the number 13) the reason commercial planes normally do not have a row 13?" Tags="&lt;aircraft-design&gt;&lt;passenger&gt;&lt;boarding&gt;" AnswerCount="6" CommentCount="14" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9123" PostTypeId="2" ParentId="9122" CreationDate="2014-10-14T12:35:09.340" Score="17" Body="&lt;p&gt;Aircraft producers don't choose numbering schemes, it's up to the airline to specify layout, row numbers, lavatory placement, etc. Airlines think about their customer base, and in the western world the occasional person has a fear of the number 13 so some airlines choose to skip the number 13. It costs them little to do so and it shows their good will. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They'll go out of their way to skip the number 13 but they skimp on decent food and legroom. It says something about the industry, doesn't it? &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-14T12:35:09.340" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9124" PostTypeId="2" ParentId="9122" CreationDate="2014-10-14T13:30:52.573" Score="24" Body="&lt;p&gt;Fear of number 13 is known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Triskaidekaphobia&quot; rel=&quot;noreferrer&quot;&gt;Triskaidekaphobia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I randomly entered some flight numbers on &lt;a href=&quot;http://www.seatguru.com/&quot; rel=&quot;noreferrer&quot;&gt;SeatGuru&lt;/a&gt; and found that &lt;a href=&quot;http://www.seatguru.com/airlines/American_Airlines/American_Airlines_Boeing_737-800_MCE_new.php&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; one &lt;strong&gt;has&lt;/strong&gt; row 13 (aircraft is B737):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oGyvX.jpg&quot; alt=&quot;Row 13&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.seatguru.com/airlines/Jet_Airways/Jet_Airways_Boeing_777-300ER.php&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; case, there is no 13th row:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hIbhB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in &lt;a href=&quot;http://www.seatguru.com/airlines/Etihad_Airways/Etihad_Airways_Boeing_777-300ER.php&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; case, several row numbers (12, 13, 14) are skipped to adjust galleys and lavatories. This could be that they were added later or can be removed in future to add more rows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZsRU0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The bottom line is that regardless of what you name it, there remains a 13th row. If a plane is about to crash (God forbid) I would be worried about being on the plane, rather than just the seat number. There are several studies that safest seats are in the back. So, rows 1-12 may not be as unlucky as row 13.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have 12 million dollars and I can give you one million more&lt;sup&gt;1&lt;/sup&gt;, would you not take it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In several parts of the world &lt;a href=&quot;http://en.wikipedia.org/wiki/Lucky_Thirteen&quot; rel=&quot;noreferrer&quot;&gt;13 is a lucky number&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;em&gt;Trust me, I will not do it, even if I have that much money.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-15T22:03:05.570" LastActivityDate="2014-12-15T22:03:05.570" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9126" PostTypeId="1" CreationDate="2014-10-14T14:37:59.320" Score="17" ViewCount="1704" Body="&lt;p&gt;Airplanes prefer to land into the wind, and airports adjust for changing wind direction by changing the active runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been flying a small plane in the pattern when the tower asked me to do a 180&amp;deg; turn to reverse the pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But at a large airport with traffic continuously coming-n-going, with fast moving jets that fly enormous patterns, how do they switch directions?   It seems logistically complicated.   &lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2019-01-15T17:54:41.493" Title="How does a large airport switch flow?" Tags="&lt;airport&gt;&lt;wind&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9127" PostTypeId="2" ParentId="9126" CreationDate="2014-10-14T15:24:05.913" Score="18" Body="&lt;p&gt;It's not too logistically complicated on its own.  You just stop takeoffs, start taxiing the conga line of waiting airplanes to the new runway, let airplanes currently on final land, and start vectoring the other airborne flights toward the new approaches once the last of takeoff traffic is away.  Once the new landing flow is established, start releasing the takeoffs.  This will require coordination between tower and approach and may involve the center if flights need to be put in holding during the transition (depends on how busy the airspace is).  In certain busy airspace this may also require coordination with other nearby airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that said, some airports that take off and land on different runways can have impacts on arrival rates in different configurations, and this adds to the logistic complication.  One example is KIAH, which in normal flow is taking off on the 15's and landing on the 26's and 27.  It isn't too much trouble to switch landing traffic to the 8's and 9, but if takeoffs have to be switched to 33 then the flow rates are negatively impacted.  It gets even worse if landing and takeoff traffic have to be put on the same runways.  How the arrival and departure flows are impacted (if at all) from a runway switch will depend strongly on the specific geometry of the runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally, the logistic impact of reduced arrival and departure flow is probably the largest impact.  At KIAH they will run their normal flow until the wind gets so bad that pilots start refusing clearances for tailwind limitations, and only then will they switch the departures to northbound.  Similarly, as soon as the tailwind is legal, they'll switch back to southbound departures.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="28837" LastEditDate="2019-01-15T15:07:57.323" LastActivityDate="2019-01-15T15:07:57.323" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="9128" PostTypeId="2" ParentId="9122" CreationDate="2014-10-14T16:05:03.190" Score="10" Body="&lt;p&gt;It might also be economical thinking behind it: Many people in the west do not want to sit in row 13, so leaving it completely out makes it one less special wish customers can utter (and therefore one less thing the airline has to care about).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Worked beside my studies at several places. One was a European airline's help-line. They had no. 13 and we had an incredible number of calls of people asking to be re-seated... Not having a 13 solves this problem entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way: I find your wording in the question very aggressive towards people with this issue. It sounds like you considered them dumb. In fact it is people of high intelligence who tend to be neurotics of this kind. I had a professor back at the ETH who hated the number 17. He's well-renowned and well-known in his area but wherever he goes, he will never sit on seat 17, in row 17 or reside in room 17 (or even just ending in 17).&lt;/p&gt;&#xA;" OwnerUserId="3916" LastEditorUserId="3916" LastEditDate="2014-10-14T19:53:59.503" LastActivityDate="2014-10-14T19:53:59.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9129" PostTypeId="2" ParentId="9117" CreationDate="2014-10-14T16:13:04.250" Score="11" Body="&lt;p&gt;This probably won't cause you any practical trouble unless you go for a new certificate or rating (the data on your medical needs to match the data on your IACRA form which needs to match your existing certificates - an examiner may refuse to conduct a test if there are discrepancies).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's something you should correct though: It's presumed your hair color on the medical is your &lt;em&gt;natural&lt;/em&gt; hair color, and if you get ramp checked you don't want to have to explain the discrepancy.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Counterintuitively the answer for &quot;How do I fix this?&quot; is buried &lt;a href=&quot;https://iacra.faa.gov/iacra/faq.aspx&quot;&gt;in the IACRA FAQ&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Q:&lt;/strong&gt;    The data on my medical certificate does not match what is in the FAA Airman Registry database, what should I do?  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;A:&lt;/strong&gt;    If it is less than 60 days since the date of issue of your certificate, contact your AME (Aeromedical Examiner) for resolution of this issue. If it is 60 days or more since the date of issue of your certificate, contact the FAA Aerospace Medical Certification Division for resolution of this issue. The contact info is below.  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Aerospace Medical Certification Division, AAM-300 &#xA;Federal Aviation Administration Civil Aerospace Medical Institute &#xA;P.O. Box 25082 Oklahoma City, OK 73125&#xA;Tel: (405) 954-4821&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-10-14T16:13:04.250" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9130" PostTypeId="2" ParentId="8665" CreationDate="2014-10-14T16:44:27.330" Score="-4" Body="&lt;p&gt;The B-52 is slower, less survivable, more expensive, and can't carry anywhere near the payload of a B-1B. In fact, it can only carry 56% the bomb weight of the B-1B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the removal of the AGM-129 ACM from service, the B-52 no longer has any capability to deliver nuclear weapons into airspace defended by modern SAM systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why is it in service? Likely political considerations concerning base closures.&lt;/p&gt;&#xA;" OwnerUserId="1311" LastActivityDate="2014-10-14T16:44:27.330" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9132" PostTypeId="2" ParentId="9122" CreationDate="2014-10-14T21:08:01.737" Score="3" Body="&lt;p&gt;I don't know about airplanes, but I believe it is the reason why hospitals do not have any room labeled as room 13 on any of their floors. Room 413 on the 4th floor is labeled as room 414.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only assume that patients who are already anxious about their illness will reach out for an excuse, no mater how absurd, that might be hindering their recovery, and therefore they result in having Triskaidekaphobia. It is their attempt to find something to blame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hospital administrators do not want to be constantly handling complaints and requests from people asking to be moved to another room, so they simply have no room 13 to begin with. &lt;/p&gt;&#xA;" OwnerUserId="3923" LastEditorUserId="65" LastEditDate="2015-03-09T20:19:02.180" LastActivityDate="2015-03-09T20:19:02.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9133" PostTypeId="2" ParentId="9116" CreationDate="2014-10-14T21:23:17.540" Score="25" Body="&lt;p&gt;I used to be an F111 test engineer; the jet can hold about 19000 liters of fuel (without external tanks).  At 0.81kg/Liter, that's 15390Kg (33,939 Lbs) of weight, which is substantial (the empty weight of the jet is &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;45200 Lbs / 20,500 Kg&lt;/a&gt;).  Basically with a full load of fuel, the jet is 75% heavier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the giant flame plume is cosmetic, the F111 can &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Fuel_dumping&quot; rel=&quot;noreferrer&quot;&gt;dump fuel&lt;/a&gt; like this in case you need to quickly reduce the weight of the aircraft; in-flight emergencies are one possible reason to reduce weight quickly. The fire is because the pilot lit the afterburners whilst dumping fuel. Assume you loose your flaps, or maybe you discover the brake lines are leaking... if you had to land on a short field (such as a small civilian airport), it makes sense to dump your fuel so you have a better chance of stopping quickly.&lt;/p&gt;&#xA;" OwnerUserId="318" LastEditorUserId="318" LastEditDate="2017-05-24T13:09:02.213" LastActivityDate="2017-05-24T13:09:02.213" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9134" PostTypeId="1" AcceptedAnswerId="9233" CreationDate="2014-10-14T21:29:39.290" Score="10" ViewCount="2874" Body="&lt;p&gt;First off, I am asking similar, but logistically different question to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1072/what-process-do-i-follow-to-land-a-civilian-aircraft-on-a-military-base&quot;&gt;What process do I follow to land a civilian aircraft on a military base?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I am in the US Military (with a valid ID), am I free to land my personal (civilian style) airplane (with my civilian licence) at military bases - in the same sense that I could drive my car on?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-10-20T11:54:58.923" Title="Can military personnel land their own private aircraft at military bases?" Tags="&lt;military&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9135" PostTypeId="1" AcceptedAnswerId="9149" CreationDate="2014-10-14T22:18:01.287" Score="5" ViewCount="2347" Body="&lt;p&gt;If a mistake is found on a pilot license, like the pilot's nationality, date of birth, or a missing type rating, how would one go about having it corrected?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-10-15T18:47:58.563" Title="How do you correct a mistake on a pilot license?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9136" PostTypeId="2" ParentId="1917" CreationDate="2014-10-14T23:21:11.770" Score="4" Body="&lt;p&gt;If you have one engine, it pretty much has to be on the centerline.  Otherwise, you'd have asymmetric thrust and you'd have to deflect the rudder, all the time, to maintain straight flight.  This causes drag.  Put it on the front, in a &quot;tractor&quot; configuration.  Or on the back, in a &quot;pusher&quot; configuration.  Or on top (see Lake Buchaneer/Renegade).  Either way, put it on the centerline of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have two or three engines,  you usually want those as close to the centerline as possible.  In the event that one of the engines shuts down (intentionally or otherwise), you want the remaining thrust to be as close to symmetric as possible, for the above reason.  Bill Lear was fond of saying that, in a twin-engine aircraft, each engine was just powerful enough to get you to the scene of the crash.  Meaning that, for many twin-engine aircraft, if you lost one engine, the other engine could keep you airborne until you could no longer counter the asymmetric thrust and you lost control and crashed.  This why Lear Jets all have fuselage mounted engines (as close to the centerline as possible) and the last airplane he was developing (the Lear Fan) had twin turboprop engines driving only one prop.  If you lost one of the engines in THAT bird, you had less power but your thrust was still perfectly symmetric.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are aircraft which have &gt; 3 engines, mounted close to the fuselage.  The Lockheed JetStar comes to mind, as does the Comet.  Unfortunately, putting multiple jet engines next to each other causes problems with the airflow around the air intakes, which can reduce the efficiency of the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the meantime, you also have the issue of weight.  Aircraft are designed so that the center of gravity (or center of mass, if you prefer) is on the wings because that's where the lift is.  One of the heaviest things a modern jetliner is carrying is ... fuel.  Not surprisingly, many of them have most of their fuel storage in their wings.  Another of the heaviest things they're carrying is ... the engines.  If you put the engines on the wings you have to have a significant-sized fin and rudder to keep it straight in an engine-out situation, but the forward-aft weight balance works out nicely.  Putting all that weight on the wings also means that the rest of the fuselage is bearing less of a load, which means the structure can be, relatively, lighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, for large jetliners with massive high-bypass turbofans, you want the intakes spaced out as much as possible, for maximum efficiency, and you want them close to the wings so that much of the weight and the lift are easily connected.  Of course, being able to use gravity to drain fuel down, from the wings into the engines, also means the engines are more likely to get fuel if there's an electrical problems (which could shut down the fuel boost pumps).&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="2859" LastEditDate="2014-11-18T14:35:37.687" LastActivityDate="2014-11-18T14:35:37.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9137" PostTypeId="1" CreationDate="2014-10-15T00:04:52.023" Score="8" ViewCount="1338" Body="&lt;p&gt;On the web, on several sites, the A-10 is listed with a ceiling of 14 km, the Su-25 with 7 km, although there is data that puts the height for the Su-25 at 10 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, why would the Su-25 fly only half as high as the A-10 knowing that the Su-25 has more engine power and is much lighter? &lt;/p&gt;&#xA;" OwnerUserId="3914" LastEditorUserId="1467" LastEditDate="2014-10-15T10:19:01.867" LastActivityDate="2015-05-10T09:41:35.087" Title="Why would a Su-25, which has more power and is much lighter than an A-10, only fly half as high?" Tags="&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9138" PostTypeId="2" ParentId="9137" CreationDate="2014-10-15T01:16:09.560" Score="3" Body="&lt;p&gt;Engines have different performance at different altitudes first of all. Additionally, I would suspect (I can't remember) that the SU-25 doesn't have pressurization equipment. Additionally, the wings on the SU-25 are smaller. An aircraft generating less lift can't fly as high, and this is likely the main reason.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2014-10-15T01:16:09.560" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9139" PostTypeId="2" ParentId="9137" CreationDate="2014-10-15T01:22:19.857" Score="7" Body="&lt;p&gt;I may be mistaken, but you seem to be using the same logic one would use to assess automobile performance.  With a car, power to weight affects one of its major performance characteristics: acceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a plane, power to weight still affects acceleration performance and (ultimately) top speed.  But it has less to do with how high the plane can fly.  Altitude is determined by the design of your wing and at what altitudes the engines can function.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, as you go higher there is less air. Less air means that the wing produces less lift, and it also means that the engines will often produce less power. You can compensate for this by other design means (like adding a turbo to the engine for example), but if you don't eventually you'll get to an altitude that you can't get past.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be fair, both of these aircraft are designed for low altitude flying (ground attacks, mostly).  So it would be mostly pointless to fit a bunch of stuff to allow the craft to fly much higher than a couple miles or so.  Thus I'm willing to bet the engineers just skipped out on that stuff to save weight for other things (like guns, missiles, armor, etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This, of course, all assumes that the information being given out on the craft is accurate.  I'm sure it's all top secret, and I doubt Russia or the US are going to just hand out hard numbers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;jwenting&lt;/strong&gt; commented that, in reality, the difference between high altitude and low altitude design generally has to do with optimization, not adding &quot;stuff&quot;.  This is a great point, for some reason my head was thinking &quot;turbo/supercharger&quot; (which doesn't even make sense with jets).  I would maintain that, in many cases, you are adding stuff to get to a higher altitude (pressurization stuff, for example).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, and this is jwentwings main point I think, when you look at the aerodynamics of an aircraft the main difference is a matter of optimization.  A wing that has good lift, good maneuverability and good stability at low altitude/speed, is not going to be so great at high altitude/speed.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="938" LastEditDate="2015-02-16T00:46:27.247" LastActivityDate="2015-02-16T00:46:27.247" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9142" PostTypeId="1" AcceptedAnswerId="9166" CreationDate="2014-10-15T08:46:14.743" Score="15" ViewCount="316" Body="&lt;p&gt;My dad will be flying us in a private aircraft from Nigeria back to the UK. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that he has been in touch with someone from the UK about this, but since I wasn't present for the conversation I'm not sure what was discussed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What precautions and declarations should a pilot make when coming from a heavily infected area? We will be landing at a private airport so the current screenings done by major airports will not be considered.&lt;/p&gt;&#xA;" OwnerUserId="3103" LastEditorUserId="69" LastEditDate="2014-10-15T15:14:53.737" LastActivityDate="2014-10-16T09:01:58.480" Title="What is required to fly privately from a region with high levels of the ebola virus (Nigeria) to the UK?" Tags="&lt;safety&gt;&lt;flight-planning&gt;&lt;easa-regulations&gt;&lt;uk&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9143" PostTypeId="2" ParentId="9122" CreationDate="2014-10-15T11:09:38.310" Score="4" Body="&lt;p&gt;It's essentially 100% free for an aircraft production team to skip row 13 and go straight from 12 to 14, when numbering. Why would you &lt;em&gt;not&lt;/em&gt; do this, and risk upsetting a minority of your paying customers who may have a less enjoyable flight because they are superstitious? It isn't particularly relevant whether &lt;em&gt;you&lt;/em&gt; think it's silly: it's a cost-benefit thing.&lt;/p&gt;&#xA;" OwnerUserId="1931" LastActivityDate="2014-10-15T11:09:38.310" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9144" PostTypeId="1" AcceptedAnswerId="9220" CreationDate="2014-10-15T12:50:31.687" Score="6" ViewCount="8644" Body="&lt;p&gt;When aircraft engines are evaluated in a test flight, how is the thrust of the engine measured?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would need accurate thrust numbers to calculate the real-world specific fuel consumption (i.e. not in a controlled environment like an engine on a test bed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd assume it is nearly impossible to measure thrust &lt;em&gt;indirectly&lt;/em&gt; with any accuracy since so many factors are involved (wing shape, wind, air density, lift, ...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I guess there should be a way to measure thrust &lt;em&gt;directly&lt;/em&gt;, probably in the engine pylon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how is engine thrust measured in flight?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="64" LastEditDate="2015-01-09T23:51:59.703" LastActivityDate="2015-04-25T04:37:51.647" Title="How is engine thrust measured in flight?" Tags="&lt;flight-testing&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9145" PostTypeId="1" AcceptedAnswerId="9161" CreationDate="2014-10-15T12:52:54.103" Score="14" ViewCount="2026" Body="&lt;p&gt;If one were to parachute out of a jumbo jetliner, would wake turbulence from the plane be an issue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 747 for instance produces much more wake turbulence than the smaller planes usually used to drop parachutists. Would that make a difference, or does the trajectory of a parachutist stay clear of wake turbulence in any case?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="65" LastEditDate="2015-03-13T15:32:21.087" LastActivityDate="2015-03-13T15:32:21.087" Title="How does wake turbulence affect parachutists?" Tags="&lt;aerodynamics&gt;&lt;parachute&gt;&lt;wake-turbulence&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9146" PostTypeId="2" ParentId="9145" CreationDate="2014-10-15T13:38:39.750" Score="6" Body="&lt;p&gt;Wake turbulence is caused by an aircraft as it moves through the air, so the turbulence is in the trail of the aircraft. A parachutist isn't going to be behind the aircraft after jumping out of a jumbo jet as there's only doors on the side. Say the airplane has a rear ramp like a 727, the parachutist is very quickly going to drop below the level of any wake turbulence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't mean jumping out of a jumbo jet is anything but extremely hazardous though, the slipstream would make any attempt foolhardy. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-15T13:38:39.750" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9147" PostTypeId="1" AcceptedAnswerId="9155" CreationDate="2014-10-15T13:41:21.920" Score="16" ViewCount="1402" Body="&lt;p&gt;Barotrauma is damage of lungs by air overpressure and may occur at overpressure as low as 30 kPa (4 psi). Overpressure in most aircraft is about double that value. So is it possible to suffer barotrauma when rapid&lt;sup&gt;1&lt;/sup&gt; decompression occurs? In an airliner or only in small airplane? And did it happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;If the decompression is explosive and the aircraft falls apart almost certainly, but it does not matter as all occupants will be dead either way. Only consider the case when the aircraft remains controllable.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="62" LastEditDate="2014-10-15T15:27:19.987" LastActivityDate="2014-10-16T13:36:59.943" Title="Is it possible to suffer barotrauma during decompression?" Tags="&lt;safety&gt;&lt;cabin-pressure&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9148" PostTypeId="2" ParentId="9145" CreationDate="2014-10-15T13:47:21.203" Score="13" Body="&lt;p&gt;Paratroopers are sometimes dropped from large cargo carriers planes out of the backdoor (or side door) with little trouble. (right in the wake turbulence)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However by the time you open your parachute you will already be well clear of any turbulence caused by the large airplane.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-15T13:47:21.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9149" PostTypeId="2" ParentId="9135" CreationDate="2014-10-15T13:49:20.537" Score="5" Body="&lt;p&gt;I had this happen to me on my first license. I got in touch with the FAA Examiner and he had me contact the local Flight Standards Office (FSDO) who corrected it for me.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If it was a mistake on the application, your Certifying Officer (read: FAA Examainer) can allow you to edit the information through IACRA (&lt;a href=&quot;https://iacra.faa.gov/iacra/default.aspx&quot; rel=&quot;nofollow&quot;&gt;https://iacra.faa.gov/iacra/default.aspx&lt;/a&gt;) and the license re-issued.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all of the information was correct, but it was misprinted, you would want to call your local FSDO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FSDO Search: &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/about/office_org/field_offices/fsdo/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your local FSDO can help you with:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Low-flying aircraft&lt;/li&gt;&#xA;&lt;li&gt;Accident Reporting&lt;/li&gt;&#xA;&lt;li&gt;Air carrier certification and operations&lt;/li&gt;&#xA;&lt;li&gt;Aircraft maintenance&lt;/li&gt;&#xA;&lt;li&gt;Aircraft operational issues&lt;/li&gt;&#xA;&lt;li&gt;Aircraft permits&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Airmen certification (licensing) for pilots, mechanics, repairmen, dispatchers, and parachute riggers&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Certification and modification issues&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;Enforcement of Airmen &amp;amp; Aircraft Regulations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3930" LastEditorUserId="64" LastEditDate="2014-10-15T18:47:58.563" LastActivityDate="2014-10-15T18:47:58.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9150" PostTypeId="2" ParentId="9135" CreationDate="2014-10-15T13:55:29.773" Score="3" Body="&lt;p&gt;Contact &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot; rel=&quot;nofollow&quot;&gt;your FSDO&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing personal details like date of birth or nationality requires the pilot to &lt;a href=&quot;https://www.faa.gov/pilots/lic_cert/change/name_change/&quot; rel=&quot;nofollow&quot;&gt;visit the FSDO personally&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to see how a type rating could be missing because completion of the rating should be logged in &lt;a href=&quot;https://iacra.faa.gov/iacra/&quot; rel=&quot;nofollow&quot;&gt;IACRA&lt;/a&gt; and that will trigger the issuance of a new license, so the 'worst' that could happen is that the FAA doesn't issue the new certificate quickly enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But obviously sometimes things just go wrong (I had an instrument rating go missing completely, despite IACRA) and in that case you would also follow up with the FSDO to get the certificate re-issued or corrected.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-15T13:55:29.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9151" PostTypeId="2" ParentId="9122" CreationDate="2014-10-15T14:35:05.880" Score="4" Body="&lt;p&gt;Consider that in Italy number 17 is also an unlucky number. This is why &lt;a href=&quot;http://www.seatguru.com/airlines/Alitalia_Airlines/Alitalia_Airlines_Airbus_A330_200.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alitalia (amongst others) removes both rows 13 &lt;strong&gt;and&lt;/strong&gt; 17&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jWuA8.png&quot; alt=&quot;Alitalia removes rows 13 and 17&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3932" LastEditorUserId="3932" LastEditDate="2019-10-16T07:01:01.713" LastActivityDate="2019-10-16T07:01:01.713" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9152" PostTypeId="2" ParentId="9145" CreationDate="2014-10-15T15:21:41.953" Score="5" Body="&lt;p&gt;Bottom line is that there is very little effect on the parachutist/skydiver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The case where there would be the largest concern would be in the event of a static line jump (which we seldom teach civilian-wise) where the jumper's pilot chute is deployed on exiting the aircraft. However, as you can see below, gravity is pulling you down faster than you are being pulled back thus you are essentially out of the turbulence cone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of non-static line jumps, the process is just faster (because of less drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, many times an aircraft will be at a slight climb and near stall speed (but this is manly for safety not turbulence related issues).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/doNmg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mcPMM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3699" LastActivityDate="2014-10-15T15:21:41.953" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9153" PostTypeId="1" AcceptedAnswerId="9159" CreationDate="2014-10-15T16:07:12.830" Score="22" ViewCount="36003" Body="&lt;p&gt;Why do most single propellers have a clockwise rotation (seen from the pilot's point of view)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pbUF3.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are though multi-engine planes that have each propeller rotating different directions, but in the case of &lt;strong&gt;single&lt;/strong&gt; propellers, it seems that clockwise rotation is dominant, or even the only option. Is there any &lt;strong&gt;single&lt;/strong&gt; propeller plane with counterclockwise rotation?&lt;/p&gt;&#xA;" OwnerUserId="1913" LastEditorUserId="1913" LastEditDate="2014-10-15T21:00:45.793" LastActivityDate="2021-01-29T06:02:52.760" Title="Why do most single propellers have a clockwise rotation?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;aircraft-systems&gt;" AnswerCount="7" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9154" PostTypeId="2" ParentId="9153" CreationDate="2014-10-15T18:48:16.233" Score="2" Body="&lt;p&gt;They don't! In s̶o̶v̶i̶e̶t̶ Russia, they rotate counterclockwise. Additionally, on some multiengine aircraft, they rotate opposite directions to cancel the p-factor.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="3048" LastEditDate="2014-10-15T20:23:09.397" LastActivityDate="2014-10-15T20:23:09.397" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9155" PostTypeId="2" ParentId="9147" CreationDate="2014-10-15T19:36:15.793" Score="12" Body="&lt;p&gt;Briefly: yes, it's possible (but very unlikely); small pressurized aircraft are the more likely scenario; maybe it has happened but if so it's very rare.&lt;/p&gt;&#xA;&lt;p&gt;According to the FAA's AC on &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-107B.pdf&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Aircraft Operations at Altitudes&#xA;Above 25,000 Feet Mean Sea Level or Mach&#xA;Numbers Greater Than .75&lt;/em&gt;&lt;/a&gt; it's possible and more likely to happen in a smaller pressurized aircraft:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Explosive Decompression. A change in cabin pressure faster than&#xA;the lungs can  decompress. Most authorities consider any decompression&#xA;that occurs in less than 0.5 seconds as  explosive and potentially&#xA;dangerous. This type of decompression is more likely to occur in small&#xA;volume pressurized aircraft than in large pressurized aircraft and&#xA;often results in lung damage. [...]&lt;/p&gt;&#xA;&lt;p&gt;(b) Rapid&#xA;Decompression. A change in cabin pressure where the lungs can&#xA;decompress faster than the cabin. The risk of lung damage is significantly lower in this decompression compared to an explosive decompression.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Unfortunately they don't cite any statistics or source for the statement &amp;quot;often results in lung damage&amp;quot; so it isn't clear when it has actually happened. Other sources suggest that it's very rare, for example &lt;em&gt;Beyond the Black Box: The Forensics of Airplane Crashes&lt;/em&gt; &lt;a href=&quot;http://books.google.com/books?id=7iWHzkchNv4C&amp;amp;pg=SA4-PA29&amp;amp;lpg=SA4-PA29&amp;amp;dq=aircraft%20decompression%20lungs&amp;amp;source=bl&amp;amp;ots=WDv-2X9HhI&amp;amp;sig=tG-FkEP2QwDvMERfgZN6Ci0qAS0&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=x8A-VNCwE8nJgwSm14GYBQ&amp;amp;ved=0CEgQ6AEwBzgK#v=onepage&amp;amp;q=aircraft%20decompression%20lungs&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;says&lt;/a&gt; this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The Air Force reports no serious injuries resulting from rapid&#xA;decompression with open airways, even while wearing an oxygen mask.&#xA;However, disastrous, even fatal consequences can result if the breath&#xA;is forcibly held with the lungs full of air. [...]&lt;/p&gt;&#xA;&lt;p&gt;Lung damage is considered nearly impossible in a commercial aircraft&#xA;because of the large volume of air inside the plane. [...] Even &lt;a href=&quot;http://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;noreferrer&quot;&gt;Aloha&#xA;Flight 243&lt;/a&gt; [...] did not decompress fast enough to cause internal&#xA;injuries.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In other words, it's not going to happen unless you hold your breath, but &lt;a href=&quot;http://www.avweb.com/news/aeromed/181893-1.html?redirected=1&quot; rel=&quot;noreferrer&quot;&gt;another source&lt;/a&gt; says that you won't be able to do that anyway:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;I've had pilots tell me they would be able to hold their breath [in order to extend the &lt;a href=&quot;http://en.wikipedia.org/wiki/Time_of_useful_consciousness&quot; rel=&quot;noreferrer&quot;&gt;time of useful consciousness]&lt;/a&gt;. That won't happen. First of all, the surprise of&#xA;the event will override any defensive measure you may have thought you&#xA;could put into place. Secondly, the rapid change in pressure&#xA;differential will make it impossible to hold your breath. (Remember,&#xA;we can be talking about a pressure differential of 8.8 PSI. Let's put&#xA;these pressure differentials into perspective. A differential of 8.8&#xA;PSI is 1267 pounds per square foot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I think the surprise is a key point here: the &lt;a href=&quot;http://en.wikipedia.org/wiki/Fight-or-flight_response&quot; rel=&quot;noreferrer&quot;&gt;flight or fight response&lt;/a&gt; increases your breathing rate so even if it were physically possible to hold your breath it's extremely unlikely that you would do so.&lt;/p&gt;&#xA;&lt;p&gt;Interestingly, Google finds numerous sources that claim lung injuries are commonly caused by aircraft decompression, but I couldn't find any source that mentioned a specific incident or even any statistics on it. I did find &lt;a href=&quot;http://books.google.com/books?id=KzXPJ-p75QIC&amp;amp;q=decompression#v=snippet&amp;amp;q=decompression&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;one book&lt;/a&gt; that studied 47 incidents of aircraft decompression but there was only one single barotrauma event among them and it affected the ears, not the lungs.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-16T13:36:59.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9156" PostTypeId="1" AcceptedAnswerId="9157" CreationDate="2014-10-15T20:37:33.167" Score="10" ViewCount="4478" Body="&lt;p&gt;Yes I know, Captain has authority over First Officer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was reading about &lt;a href=&quot;http://en.wikipedia.org/wiki/Airblue_Flight_202&quot;&gt;Airblue Flight 202&lt;/a&gt; and according to the investigation, First Officer said these words 40 seconds before crash:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sir turn left, Pull Up Sir. Sir pull Up.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although many sources have questioned the investigation and its subsequent report, because of several facts including how the captain with over 25,000 hours and an unblemished flight safety record could make such mistake when he is so much familiar with the terrain etc., my question isn't about that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I want to know is that in case of an emergency or a similar incident of an imminent crash (as mentioned above), can a captain &lt;strong&gt;order&lt;/strong&gt; the First Officer not to touch anything, or ignores his warnings or simply not listen to him at all? What the First Officer has to do or can do?&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="572" LastEditDate="2015-02-19T08:58:06.517" LastActivityDate="2015-02-19T08:58:06.517" Title="Who has the authority between captain and first officer in emergencies?" Tags="&lt;emergency&gt;&lt;accidents&gt;&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9157" PostTypeId="2" ParentId="9156" CreationDate="2014-10-15T20:51:38.383" Score="15" Body="&lt;p&gt;Authority in the cockpit, especially in emergency, is very important in a principle called &lt;strong&gt;Crew Resource Managment&lt;/strong&gt;, or &lt;a href=&quot;http://en.wikipedia.org/wiki/Crew_resource_management&quot;&gt;CRM&lt;/a&gt;. A number of incidents similar to your example led to the formulation of this concept to enhance the coordination between the crew. The idea is that all crew members should be working together as effectively as possible to solve the problems at hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In emergencies, the crew need to be able to communicate. This means that the first officer should be willing to question the Captain, like they did in your example. They should also be willing to take action if they feel it necessary. However, communicating this action is also important, as evidenced in the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Air France 447&lt;/a&gt;, where the pilots were commanding different inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither of the pilots should be &lt;strong&gt;ordering&lt;/strong&gt; the other to do anything unless absolutely necessary. They need to get the attention of the other pilot, state the problem, say why it's a problem, and suggest a solution to the problem. Then they need to agree on a plan of action, and be clear about who is in control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your example, the captain's negative attitude may have prevented the first officer from saying anything more.  A better response from the first officer would have been to say something more along the lines of, &lt;em&gt;&quot;Sir, we are flying towards high terrain, we are not flying high enough to clear it. We need to either climb over it or turn left to avoid it. Do you agree?&quot;&lt;/em&gt; This makes it clear to the captain what problem the first officer sees, and is clear about how the first officer thinks they should respond. It also includes a direct question for the captain to answer. Both pilots should be ready to communicate like this if necessary, and should also be making sure that they aren't creating an environment where the other pilot isn't comfortable with doing so. If the first officer still got no response, he should have been willing to take control, and should communicate to the captain that he is doing so, including the previously stated information about what actions he intends to take.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-16T15:13:05.963" LastActivityDate="2014-10-16T15:13:05.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9158" PostTypeId="1" CreationDate="2014-10-15T21:16:37.727" Score="2" ViewCount="121" Body="&lt;p&gt;Lately I've seen a lot of aircraft that have the wingtips curved up.  What is the reason for this?&lt;/p&gt;&#xA;" OwnerUserId="3940" LastEditorUserId="247" LastEditDate="2014-10-17T07:10:21.817" LastActivityDate="2014-10-17T07:10:21.817" Title="Why do newer commercial aircraft have their wingtips curved up?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2014-10-15T22:21:40.930" ContentLicense="CC BY-SA 3.0" />
  <row Id="9159" PostTypeId="2" ParentId="9153" CreationDate="2014-10-15T23:15:34.410" Score="16" Body="&lt;p&gt;I wasn't able to find any good historical references, so this answer is pure opinion.  (sorry).  I'll break this down into two separate questions.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there any reason for single-engine propellers to turn the same way?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Yes.  When flying, the spin direction of the prop has several effects.  Helical prop wash, p-factor, gyroscopic precession, differing blade angles of attack all are due to the asymmetry of spinning in a single direction.  An experienced pilot will want to understand and compensate for these effects when necessary.  It is easy to see that once this is understood, a single configuration will be preferred within a community to minimize differences between aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there any reason to prefer CW rotation over CCW as a convention in a single engine plane?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;None that I am aware of.  It appears to be simply an accident of choice.  I had wondered if the majority of engines available to early manufacturers was in that direction and made it preferable, but I couldn't find anything suggesting that.  &lt;strike&gt;Indeed today the majority of automobile engines rotate the opposite direction.&lt;/strike&gt;  Making (piston) engines rotate the other direction is not a huge problem.  Twin-engined aircraft and watercraft often have counterrotating engines and propellers.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="3159" LastEditDate="2014-10-16T08:50:46.330" LastActivityDate="2014-10-16T08:50:46.330" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9160" PostTypeId="1" AcceptedAnswerId="9164" CreationDate="2014-10-15T23:17:03.393" Score="23" ViewCount="6768" Body="&lt;p&gt;For example, the captain starts pulling back and to the right to turn right. First officer initiates a left diving turn. What happens?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="19" LastEditDate="2014-10-16T07:29:33.683" LastActivityDate="2018-10-10T13:26:15.050" Title="What happens when two different control inputs are commanded in an aircraft with two control columns?" Tags="&lt;airliner&gt;&lt;flight-controls&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9161" PostTypeId="2" ParentId="9145" CreationDate="2014-10-15T23:56:48.067" Score="18" Body="&lt;p&gt;Qualification: I am a master parachute rigger and I taught sport parachuting for 10 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The back door of a 747 is actually in a pretty good position - the tail is above the door and the fuselage is narrowing at that point so it's not a complete side exit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A freefall jumper will drop out of the aircraft's wake in under a second so that's not really an issue. If we pick a theoretical worst-case where a jumper goes straight through a huge vortex they &lt;em&gt;might&lt;/em&gt; get flipped over. Remember that a human does not have large surfaces like wings to interact with. Any jumper that can't recover from that won't be doing freefall jumps anyway. Seriously, this is in the Jump #1 stability lesson, and if you haven't got it sorted by jump #6 any reputable school will send you home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exit speed is a consideration - sport gear is meant for &amp;lt; 200km/h. If we are going out at 747 cruise speeds I would tighten everything right up&lt;sup&gt;1&lt;/sup&gt;, wrap some tape around the riser covers&lt;sup&gt;2&lt;/sup&gt; and tuck the pilot chute handle completely into the pouch. Maybe also tack the closing flap cover down. Yes guys, it will still open if you sew it to the proper flap. If the plane is at approach speeds with flaps and gear down then you're fine - not much different than a King Air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in conclusion, yes, you can jump out of a 747. Rent one and you will have every jumper in the state lining up for tickets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To reply to the comment of the pilot chute going over the tail, that happened at our place too (and to me once, but mine went under the tail). It's got nothing to do with turbulence - the pilot chute got pulled mostly out of the pouch, most likely snagging something, and the air picked it up from there. Our guy actually hit the tail. He had nasty bruises and needed a few lines changed, the pilot needed new underwear, and the Cessna needed a bunch of rivets and sheet metal work. When it happened to me I had a surprise deployment at 9,500 feet and a longer than usual ride down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; to the point where you will need my tools to close it.&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt; it will break away after opening, and won't be more than an annoyance if it doesn't&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorDisplayName="user3338" LastEditDate="2014-10-16T12:05:12.737" LastActivityDate="2014-10-16T12:05:12.737" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9162" PostTypeId="2" ParentId="9160" CreationDate="2014-10-16T01:21:16.917" Score="4" Body="&lt;p&gt;In an airplane when two pilots are actively sitting on the controls, only one is actually flying the airplane. The other is normally watching over the actions of the pilot flying the airplane. Hence the terms are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot Flying (PF) &lt;/li&gt;&#xA;&lt;li&gt;Pilot Not Flying (PNF) or Pilot Monitoring (PM)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;They can switch the responsibility of actual flying at will, or if the captain &lt;em&gt;orders&lt;/em&gt; as he/she is the legal commander and always responsible for the aircraft. From &lt;a href=&quot;http://en.wikipedia.org/wiki/First_officer_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Even when the first officer is the flying pilot, however, the captain&#xA;  remains ultimately responsible for the aircraft, its passengers, and&#xA;  the crew. In typical day-to-day operations, the essential job tasks&#xA;  remain fairly equal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When the pilots want to switch the responsibility of flying, they exercise the routine known as &lt;strong&gt;Positive Exchange of Flight Controls&lt;/strong&gt;. This can be performed as following:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;PF: You have the controls or Your plane&#xA;PNF: I have the controls or My plane&#xA;PF: You have the controls or Your plane&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;PNF: I have the controls or My plane&#xA;PF: You have the controls or Your plane&#xA;PNF: I have the controls or My plane&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I've read some people doing the first two lines only, although it is not the standard way.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you are referring to the fact that both pilots are actually applying contradicting control inputs, then obviously it is not a good thing. It can break the control surface, or the cables connecting them (no in case of &lt;a href=&quot;http://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;nofollow&quot;&gt;fly-by-wire&lt;/a&gt;) or &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow&quot;&gt;even can get very deadly&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-10-16T01:21:16.917" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9163" PostTypeId="2" ParentId="9160" CreationDate="2014-10-16T02:04:01.417" Score="11" Body="&lt;p&gt;In the case of 727-100 and 747-100 and -200 aircraft, if both pilots were exerting opposite forces on the control column, the stronger pilot would win. In these aircraft the control columns are linked by heavy duty cables or rods. I don't believe it would be possible for human strength to break them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabling feeds into hydraulic valves, which use hydraulic pressure to move the control surfaces. However, the 727-100 has manual reversion, which enables the pilots to move the control surfaces by the cabling alone should all hydraulic pressure be lost. We used to practice this in the simulator. When flaring for the landing both pilots would work together to move the elevator. &lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2014-10-16T02:04:01.417" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9164" PostTypeId="2" ParentId="9160" CreationDate="2014-10-16T02:06:16.173" Score="27" Body="&lt;p&gt;It depends on the aircraft. In any aircraft where the two control columns are linked, there's only one input to command the control surfaces. While most smaller aircraft are connected directly through the control surfaces, Boeing publicizes that on the 787 - a fly-by-wire aircraft - the control columns &quot;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q1/3/&quot; rel=&quot;nofollow noreferrer&quot;&gt;[a]re cross-linked between pilots to reduce potential confusion.&lt;/a&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Airbus aircraft (and probably others), the controls are not linked: there is no indication on one pilot's controls of the other's position. The computer handles this by adding the two inputs: opposite commands will cancel each other out, while both pilots commanding the same input will &lt;a href=&quot;http://www.skybrary.aero/index.php/A320,_Bilbao_Spain,_2001_%28WX_AW%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;increase the total commanded input&lt;/a&gt;. Some Airbus aircraft have a feature which makes an announcement of &quot;DUAL INPUT&quot; when there is input on both sidesticks simultaneously. As of &lt;a href=&quot;http://www.ntsb.gov/aviationquery/brief2.aspx?ev_id=20001208X05986&amp;amp;ntsbno=FTW96LA269&amp;amp;akey=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;January 30, 1997&lt;/a&gt;, this was &quot;an installation&quot; (optional feature, I believe) on the A320 and under development for the A340.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus aircraft also have a &lt;a href=&quot;https://aviation.stackexchange.com/q/3455/136&quot;&gt;Priority Takeover button&lt;/a&gt;, which lets one pilot take control and have the airplane ignore inputs from the other sidestick. As Farhan noted, good &lt;a href=&quot;https://aviation.stackexchange.com/q/1700/136&quot;&gt;CRM (Crew Resource Management)&lt;/a&gt; is also very important to ensure that only one command is given at once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft have linked controls, which can be separated if necessary. On the 767, if sufficient force is applied, the elevators will &quot;split&quot;: each control column will control one of the elevators. The pilot who is stronger or better prepared will have &lt;a href=&quot;https://www.formsbank.com/template/397001/aircraft-accident-brief-ntsb-aab-02-01-pb2002-910401-egypt-air-flight-990-boeing-767-366er-su-gap-national-transportation-safety-board.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;more control over the aircraft&lt;/a&gt;. There's also the &lt;a href=&quot;https://aviation.stackexchange.com/a/1832/136&quot;&gt;EMB-145 and -135&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The roll input is ... linked at the control column[.] Each yoke independently controls its own aileron -- the CA yoke only flies the left aileron and the FO yoke the right aileron. It is only through the control column linkage that each yoke can control the whole airplane. It is done this way so that if there is a problem with a cable jamming, the control interlock can be disconnected and at least half control regained.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="136" LastEditorUserId="34822" LastEditDate="2018-10-10T13:26:15.050" LastActivityDate="2018-10-10T13:26:15.050" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="9165" PostTypeId="2" ParentId="9156" CreationDate="2014-10-16T07:15:26.760" Score="8" Body="&lt;p&gt;It's entirely reasonable for the First Officer to take control if he or she seems it necessary. Especially if the captain isn't responding to prompts for corrective action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are techniques you can use, in this example the FO called the captain 'sir'. If you normally address them by they're first name you could try 'sir' or 'captain'. You could recommend the take a turn or climb with increasing assertiveness. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they fail to respond. You state 'I have control...' And tell them why. If they're not responding to prompts it's unlikely they'll be any resistance, they've probably lost situational awareness.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-16T07:15:26.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9166" PostTypeId="2" ParentId="9142" CreationDate="2014-10-16T07:21:11.033" Score="6" Body="&lt;p&gt;You'll be on a flight plan. You'll have to clear customs at a designated airport and file the appropriate paperwork. More info here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.gov.uk/government/publications/general-aviation-operators-and-pilots-notification-of-flights&quot;&gt;Notification of Flights&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you notify the border agency it will make recommendations if they think your flight poses a risk. There is only screening at Gatwick and Heathrow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.gov.uk/government/news/public-health-england-enhanced-ebola-screening-process&quot;&gt;Ebola Specific Information&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="412" LastEditorUserId="412" LastEditDate="2014-10-16T09:01:58.480" LastActivityDate="2014-10-16T09:01:58.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9167" PostTypeId="2" ParentId="9153" CreationDate="2014-10-16T08:25:31.493" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Indeed today the majority of automobile engines rotate the opposite direction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not quite. The power output of a car engine is towards the rear. The power output of an aircraft engine is toward the front. If you look straight at the flywheel / propeller end they usually turn the same way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back in WWI the first-generation fighters (We're talking Sopwith Camels and Fokker triplanes here) did have props going in either direction. The airframe manufacturer made the whole thing and props were carved by hand, so it didn't matter much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today we have a small handful of prop makers, a smaller handful of engine makers, and both of them would be quite happy if everything turned the same way. Yes, it's really easy to make a piston engine go the other way, and it's really easy to flip the prop's airfoil over, but that means making and stocking different parts. The camshaft, pumps, ignition timing, prop governor, starter, mechanical meters etc. are all directional. And don't forget the pilots - if he's used to putting left boot to it on takeoff, and rents one that needs right boot, takeoff will be interesting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your twin or multi has counter-rotating props you have some advantages if one quits but you have extra maintenance costs. Imagine the language your mechanic will use after changing the camshaft and then remembering this engine is a leftie when he tries to start it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's a geared engine then it's much easier - the engine and accessories are standard, there's just an extra (or one fewer) bit in the gearbox, plus the other-hand prop.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-16T08:25:31.493" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9168" PostTypeId="2" ParentId="6310" CreationDate="2014-10-16T09:59:17.923" Score="3" Body="&lt;p&gt;Operating with a deactivated thrust reverser is relatively common on normal line ops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are normally type specific operating restrictions e.g. full power take-off, no short or narrow runway ops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On B757/76 there is a clue that you a have a reverser locked out - you can't select it.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-16T09:59:17.923" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9169" PostTypeId="2" ParentId="8574" CreationDate="2014-10-16T11:00:07.033" Score="0" Body="&lt;p&gt;The question is quite broad but here's my understanding..&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, when there is an emergency condition e.g. engines are lost/off/unavailable (i.e. no generators) and also no APU possible, should there be any bleed fault?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, since there is no fault (as you've listed). The bleeds are in the correct config and there is no disagreement between the valve and the switch. There is just no pressure to the system. You will get a 'Bleed Off' indication if your switch is on with no pressure to the valve(type dependant). Also you will get a pack off indication - if you've got the bleeds set to feed the packs.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I know that you have things like built-in autotest stuff that goes on before the computers are powered, but surely when the aircraft is on batteries/emergency power, should there be any bleed faults?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As I said above you wont get faults, but you may get indications that the bleeds are off.&lt;/p&gt;&#xA;" OwnerUserId="412" LastEditorUserId="753" LastEditDate="2014-11-16T21:23:56.093" LastActivityDate="2014-11-16T21:23:56.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9170" PostTypeId="2" ParentId="9096" CreationDate="2014-10-16T13:09:19.633" Score="3" Body="&lt;p&gt;Early fighters with a cockpit (Supermarine Spitfire, Messerschmitt 109) had cockpits which were hinged on one side. For a right handed pilot (the majority), it was easier to lift the canopy over your head and to the right, hence the hinge was on the right. It's also easier to climb up an aircraft if your stronger arm is toward the fuselage and handholds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This made the left the obvious choice for disembarking, and since airfields slowly became set up for exiting to the left and fuel to the right, newer designs maintained the door on the left. If your stands are set up for one direction, you may as well order your new plane to fit the same workflow, so even when hoods were modified to slide backward, there was no need to change the door side (most designs were incremental, so the door was already there... Why move what already works?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This continued as air bridges and similar were introduced, and it would now be pointless to make an aircraft with doors on the other side, as you'd just be increasing your loading/turnaround times.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-10-16T13:09:19.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9171" PostTypeId="1" AcceptedAnswerId="9172" CreationDate="2014-10-16T18:15:59.170" Score="5" ViewCount="11006" Body="&lt;p&gt;All the twins I have checked have counter-rotating blades, so I was wondering if this was true for all twins of if there are any twins that have both blades turning in the same direction.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="247" LastEditDate="2014-10-17T06:36:31.553" LastActivityDate="2017-02-27T22:25:51.700" Title="Are there any twin engine aircraft without counter-rotating props?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9172" PostTypeId="2" ParentId="9171" CreationDate="2014-10-16T18:31:39.593" Score="11" Body="&lt;h3&gt;Twin enigned aircrafts without counter-rotating propellers&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;A great many twins don't have counter-rotating props:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One such aircraft is the BeechCraft Baron 58, as seen in &lt;a href=&quot;https://www.youtube.com/watch?v=vnYF1FqZa0g&quot; rel=&quot;nofollow noreferrer&quot;&gt;this YouTube video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another aircraft I can think of is the King Air 350.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not any more or less common to have one or the other. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Contra-rotating propellers&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Another interesting solution to the P-factor (prop pulling towards one direction), especially on single engine aircraft is &lt;strong&gt;contra-rotating props&lt;/strong&gt;, two propellers on the same shaft that spin in opposite directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is mainly for single engine racer aircraft, but there are multi-engine aircraft known to have it, such as the Soviet Tu-95 Bear bomber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pic shown here is a Spitfire Mk. XIV:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kqzA1.jpg&quot; alt=&quot;Spitfire Mk. XIV with contra-rotating props&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;A better explanation of the P-factor&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;P-factor is the term for asymmetric propeller loading, that causes the airplane to yaw to the left when at high angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming a clockwise rotating propeller it is caused by the descending right side of the propeller (as seen from the rear) having a higher angle of attack relative to the oncoming air, and thus generating a higher air flow and thrust than the ascending blade on the left side, which at the other hand will generate less airflow and thrust. This will move the propellers aerodynamic centre to the right of the planes centreline, thus inducing an increasing yaw moment to the left with increasing angle of attack or increasing power. With increasing airspeed and decreasing angle of attack less right rudder will be required to maintain coordinated flight.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="2556" LastEditDate="2014-10-17T09:57:02.020" LastActivityDate="2014-10-17T09:57:02.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9173" PostTypeId="2" ParentId="9171" CreationDate="2014-10-16T18:53:42.357" Score="5" Body="&lt;p&gt;Another interesting issue that effects aircraft with non counter rotating props is that they would have a &lt;strong&gt;Critical Engine&lt;/strong&gt;. This in basic terms means that it's worse if a particular engine fails. The Diamond DA42 which is a popular modem trainer has this issue if the left engine fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following from Wikipedia explains further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_engine&quot;&gt;Critical Engine&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The critical engine of a multi-engine, fixed-wing aircraft is the one whose failure would result in the most adverse effects on the aircraft's handling and performance. On propeller aircraft, there is a difference in the remaining yawing moments after failure of the left or the right (outboard) engine when all propellers rotate in the same direction due to the P-factor. On turbojet/ turbofan aircraft, there usually is no difference between the yawing moments after failure of a left or right (outboard) engine. An engine can also be called critical when it is the only engine that drives a hydraulic pump for augmenting/ boosting flight controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-16T18:53:42.357" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9174" PostTypeId="2" ParentId="9171" CreationDate="2014-10-16T20:04:44.110" Score="3" Body="&lt;p&gt;Piper Twin Comanche was available in both configuration, but the most popular one had the engines turning in the same direction.  Aztec and Apache are also models with engines spinning the same way.  My experience is that most light twins have the same direction and that counter rotating is the exception.  It makes sense that way as they share engines with singles, so one particular spinning direction is going to be much more common and spare parts will be easier to get...&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2014-10-16T20:04:44.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9177" PostTypeId="2" ParentId="9134" CreationDate="2014-10-17T00:46:56.683" Score="2" Body="&lt;p&gt;Yes, military personnel can apply for a Civil Aircraft Landing Permit for official business.&lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2014-10-17T00:46:56.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9180" PostTypeId="1" CreationDate="2014-10-17T07:54:02.297" Score="9" ViewCount="15248" Body="&lt;p&gt;I'm just finishing up my private license and am looking forward to taking some friends up in a Cessna 172.  I've invested in a nice aviation headset for myself, but, as none of my friends are pilots, they don't have headsets of their own.  Even the cheapest aviation headsets (at least that I've found) are around $100; friends going up for an occasional flight don't want to spend that kind of money, and I certainly don't want to shell out for several spare headsets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, are there adapters available so that normal headphones could be plugged into a standard 2 jack connector?  I have not been able to find any online.  While certainly not too effective at reducing noise, this would at least give my passengers some comfort and would allow me to communicate with them without shouting during these short and infrequent flights.  Worst case scenario, I could give them all earplugs, but it would definitely be helpful to have some kind of headset solution so that I'm not shouting through the sound of the prop and the earplugs and they're not shouting through my ANR.&lt;/p&gt;&#xA;" OwnerUserId="3953" LastEditorUserId="62" LastEditDate="2014-10-17T12:44:40.417" LastActivityDate="2020-06-10T17:04:04.753" Title="Is it possible to use normal headphones for passengers in a light aircraft?" Tags="&lt;general-aviation&gt;&lt;radio-communications&gt;" AnswerCount="8" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9181" PostTypeId="2" ParentId="9180" CreationDate="2014-10-17T08:44:40.980" Score="3" Body="&lt;p&gt;I'm not sure converting a regular set of headphones is the best solution. You need to be able to communicate effectively with your passenger and them with you, both for safety and for their comfort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the short term see if you could loan a set from the flight school you are training with. Long term - there seems to be some good buys on eBay, old David Clarks etc... &lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-17T08:44:40.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9182" PostTypeId="1" AcceptedAnswerId="9196" CreationDate="2014-10-17T09:18:24.873" Score="2" ViewCount="2020" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/V_speeds#V1_definitions&quot; rel=&quot;nofollow&quot;&gt;wikipedia&lt;/a&gt;, decision speed ($V_1$) is computed taking into account the runway length (and other parameters). If an aircraft uses a long runway (one listed &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_longest_runways&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;), there may be enough runway available to stop an aircraft rejecting takeoff at high speed. Thus $V_1$ can be higher than usual, perhaps greater than $V_r$ or $V_2$. Is the situation where $V_1$ is greater than $V_r$ possible?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2014-10-17T09:23:51.277" LastActivityDate="2019-05-04T22:13:20.500" Title="Is it possible to have V1 greater then Vr?" Tags="&lt;aircraft-performance&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9183" PostTypeId="1" AcceptedAnswerId="9185" CreationDate="2014-10-17T09:47:17.397" Score="10" ViewCount="11769" Body="&lt;p&gt;related questions: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5049/can-a-super-land-without-flaps-spoilers&quot;&gt;landing wihtout flaps&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1449/full-flaps-on-takeoff&quot;&gt;takeoff with full flaps&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My question focus on passengers jets (goes from Embraer E-jet family to  Airbus A380). I don't know why pilots would attempt to takeoff without flaps but lets say they will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering all the other parameters are good enough (no crosswind, long runway, aircraft light enough,...) and the pilots are aware of this unusual takeoff configuration and adapt their action accordingly (including increasing $V_r$ and $V_2$), is it possible for any passenger jet to takeoff and stay airborn (not like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Spanair_Flight_5022&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight spanair 5022&lt;/a&gt;) without extending flaps?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2020-11-26T20:01:50.920" Title="Is it possible to takeoff without flaps extended?" Tags="&lt;airliner&gt;&lt;takeoff&gt;&lt;flaps&gt;" AnswerCount="7" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="9184" PostTypeId="2" ParentId="9183" CreationDate="2014-10-17T10:55:13.510" Score="3" Body="&lt;p&gt;Sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether the aircraft is still on the runway or already airborne when it reaches the airspeed necessary for sufficient lift without flaps is rather irrelevant.&lt;/p&gt;&#xA;" OwnerUserId="3333" LastActivityDate="2014-10-17T10:55:13.510" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9185" PostTypeId="2" ParentId="9183" CreationDate="2014-10-17T11:22:52.750" Score="23" Body="&lt;p&gt;Yes take-off without flaps is possible. The Airbus A300 and Boeing 767 are approved for such take-offs and it is being done regularly. It results in a better climb gradient, especially with one engine out. The one engine out climb gradient is an important and sometimes limiting factor in take-off calculations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One important constraint is the length of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another limitation, perhaps less obvious, is the maximum rolling speed of the wheels. The tires are rated to a limited speed which may be exceeded by a flap-less take-off.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-17T16:26:13.643" LastActivityDate="2014-10-17T16:26:13.643" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9188" PostTypeId="1" CreationDate="2014-10-17T12:02:17.467" Score="67" ViewCount="35927" Body="&lt;p&gt;What factors determine the maximum altitude for a plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it limited by wing design, engine thrust, and so on?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a formula by which one can calculate the maximum altitude a plane can reach?&lt;/p&gt;&#xA;" OwnerUserId="3914" LastEditorUserId="1843" LastEditDate="2015-01-26T21:56:48.723" LastActivityDate="2019-03-18T16:44:19.467" Title="What determines the maximum altitude a plane can reach?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="9189" PostTypeId="2" ParentId="9180" CreationDate="2014-10-17T13:24:17.787" Score="0" Body="&lt;p&gt;I did some brief searching and couldn't find any adapters, although there are plenty for the  other direction, i.e. to use an aviation headset with a PC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in any case, using a regular headset would probably be a bad idea, even for short, infrequent flights. The issues are sound quality, lack of a microphone, and poor hearing protection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, you want to make sure that your passengers can hear you clearly for safety reasons. If you have to make an emergency briefing or ask them to assist you for any reason then you need to be sure that they can understand you immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, you want to be able to hear your passengers so they should have usable microphones. I always brief mine to tell me about aircraft they see that I haven't already pointed out: I can't see everywhere and using my passengers as spotters is really helpful, but it won't work if I can't hear them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, aviation headsets protect your ears - either actively or passively - from the relatively loud background noise in the cabin. Normal headsets don't do this very well and certainly not well enough for a light aircraft cabin, so your passengers will probably end up feeling somewhat deafened and uncomfortable, which isn't good for anyone and means they'll be less likely to fly with you again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the best thing you can do is just look for some cheap headsets. I've had one pair for 8 years and they still work just fine so the cost over the long term isn't so bad, although of course I know it can still be a big hit up front. \$100 isn't much at all when you consider the benefit you get from it. Alternatively most FBOs will rent you headsets for a few dollars per flight, but even then you can spend \$100 fairly quickly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-17T13:24:17.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9190" PostTypeId="2" ParentId="9180" CreationDate="2014-10-17T13:40:08.233" Score="9" Body="&lt;p&gt;There are some solutions to convert a normal set of headphones into an aircraft headset, but in total they are going to cost you more than a base level headset would.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One popular (available in TSO and non-TSO options) option is &lt;a href=&quot;https://uflymike.com/pages/what-is-harmony&quot; rel=&quot;nofollow noreferrer&quot;&gt;UFlyMike&lt;/a&gt; which is an adapter for Bose noise cancelling headphones that adds a microphone and connects to a standard 2 jack airplane audio panel.  But back to your issue at hand, this is not cheap.  The UFlyMike will set you back around \$200 and the Bose headphones are another \$300, making this adapted headset cost a total of \$500.  This is a bargain compared to an actual Bose aviation headset, which runs around \$1000, but is well above an entry level non-ANR headset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your best bet is to ebay some old clamp style headsets (e.g. DC) to get some cheap headsets and then keep around your current headset when you eventually upgrade (unless those trade-up deals from e.g. Lightspeed are too hard to resist) to build up a stock.  Alternatively, if you are renting, you may be able to rent a few headsets with the plane so everyone can be equipped for a trip.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="132" LastEditDate="2018-04-22T05:42:34.703" LastActivityDate="2018-04-22T05:42:34.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9191" PostTypeId="2" ParentId="9180" CreationDate="2014-10-17T13:42:11.987" Score="3" Body="&lt;p&gt;There is a way to use ordinary headsets. It can be done like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a picture of a normal headset jack for audio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Oi9V.jpg&quot; alt=&quot;Headset Jack&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you would need this (1/8 inch female to 1/4 inch male) adapter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CqWjP.jpg&quot; alt=&quot;Adapter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using this, you can get your passengers hear you and any communications you have with ATC or other airplanes etc.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Personally, I do not like this approach. Reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They cannot talk to you or reply you if you ask them anything.&lt;/li&gt;&#xA;&lt;li&gt;Ordinary computer headsets don't reduce noise levels on an airplane.&lt;/li&gt;&#xA;&lt;li&gt;You still need to buy an adapter which isn't commonly available at homes (like a headset).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My recommendations would be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you are renting the airplane, the owner might have inexpensive headsets available for you to borrow. Flight Schools have many headsets as not all students buy their own in the beginning specially.&lt;/li&gt;&#xA;&lt;li&gt;Flying is an expensive hobby. If you can afford it, you may buy a few extra headsets for $100 each.&lt;/li&gt;&#xA;&lt;li&gt;Ask your friends to buy their own if they want to be your frequent passengers. After all, you can taking them for a very enjoying ride without them paying you for it.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2019-08-27T11:09:08.000" LastActivityDate="2019-08-27T11:09:08.000" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9192" PostTypeId="2" ParentId="9188" CreationDate="2014-10-17T14:16:01.643" Score="7" Body="&lt;p&gt;The absolute maximum altitude a plane can reach is only limited by the lift it can produce.   This will be a function of the wing (and one of our resident engineers can explain this) and the airflow over the wing.  The airflow in turn is a function of your altitude (air density) and airspeed.  Airspeed in turn is a function of your thrust, drag, etc.  In short, the lift you can produce is dependent on a lot of things indirectly and this will define the physical limit of max altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the max altitude defined by your lift is a max continuous altitude.  If you have the momentum available you could use that to climb above this altitude for brief excursions, but you would not be able to maintain altitudes above this limit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this altitude is not the airplanes service ceiling, which is going to be lower due to climb rate thresholds (e.g. 100 fpm) or certification issues (e.g. 25,000 feet for pressurization/oxygen requirements). &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-10-17T14:16:01.643" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9193" PostTypeId="2" ParentId="9188" CreationDate="2014-10-17T15:59:08.927" Score="9" Body="&lt;p&gt;In the most basic form, the aircraft's max altitude is the point where &lt;strong&gt;thrust required is equal to thrust available&lt;/strong&gt;. This compares the thrust required to maintain airspeed and altitude to the thrust available from the engines. Since air-breathing engines will tend to produce less thrust as altitude increases, this means that the thrust available decreases with altitude. At some point, the aircraft will be at the lowest drag possible in level flight, and using all thrust available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As casey points out, there will be many other factors, such as the ability of the aircraft to remain pressurized, the ability of the engine to maintain a certain thrust level, and atmospheric conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you are looking for the absolute max altitude it's able to reach, but not necessarily maintain, it becomes much more complicated. This would be determined by the maximum amount of energy an aircraft can attain, both in altitude and airspeed. An aircraft may be able to dive or remain at a lower altitude to gain speed, and then climb to trade that speed for altitude, reaching a higher altitude than it can maintain (see &lt;a href=&quot;http://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701&quot;&gt;this incident&lt;/a&gt; for an example of an aircraft that flew to a higher altitude than it could actually maintain).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-17T15:59:08.927" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9194" PostTypeId="1" CreationDate="2014-10-17T16:06:36.890" Score="16" ViewCount="4067" Body="&lt;p&gt;Why do certain areas on passenger jet wings go dark during a flight? This effect is observed on high altitude where temperature is low. When airplane descends, wings return to their initial color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing during a flight on high altitude.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UQfUA.jpg&quot; alt=&quot;Wing during a flight on high altitude.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same wing before landing.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/C2dLF.jpg&quot; alt=&quot;The same wing before landing.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've noticed this effect in several flights on different aircrafts. It is clear that these areas are covered with other coating, but what is the purpose of this?&lt;/p&gt;&#xA;" OwnerUserId="3957" LastEditorUserId="3957" LastEditDate="2014-10-17T16:17:40.247" LastActivityDate="2018-02-14T20:44:05.300" Title="Why do wings of passenger jet go dark during a flight?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;jet&gt;&lt;altitude&gt;&lt;temperature&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9195" PostTypeId="2" ParentId="9188" CreationDate="2014-10-17T16:11:25.453" Score="65" Body="&lt;p&gt;The higher you get, the lower the density of the air becomes. This lower density results in a lower lift being generated for the same airspeed and angle of attack. Effectively, the higher you fly the higher your minimum speed becomes. So while climbing, your speed needs to increase to compensate for the lower air density. As long a you can fly faster, the lower density at altitude can be compensated for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically there are two things that limit your maximum speed: thrust and speed of sound and with that your maximum altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First is thrust; the higher you get, the lower the thrust your engines deliver. You might note that drag goes down with the air density as well but since you are flying faster and faster during the climb the drag doesn't decrease at all. If your maximum altitude is limited by thrust then at some point during the climb the thrust and drag are getting close to equal and that is where the climb stops. When you can no longer climb with more than 100ft per minute (for propeller aircraft) or 500ft per minute (for jet / turbofan aircraft) you have reached your &lt;em&gt;service ceiling&lt;/em&gt;. If the aircraft maximum altitude is determined by thrust, the absolute ceiling will take very long to reach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high altitudes air breathing engines will get difficulties eventually. Due to the lower air density the mass flow through the engine is reduced up to a point where it causes a flame out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other limitation is the speed of sound, at least for subsonic aircraft. In the process of generating lift, air flowing over the top of the wing is accelerated. At one point, when the aircraft is still flying below the speed of sound, shock waves will start to form over the wing. This results in increase of drag and reduces the lift. So provided you have enough engine power at your disposal you can climb to an altitude where your minimum speed is also your maximum speed. This is called the &lt;a href=&quot;http://en.wikipedia.org/wiki/Coffin_corner_%28aerodynamics%29&quot; rel=&quot;noreferrer&quot;&gt;coffin corner&lt;/a&gt;. In the coffin corner:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;if you fly any faster, you will exceed the maximum Mach number ($M_{mo}$) of your aircraft, resulting in high speed buffet, vibrations and possible loss of control. &lt;/li&gt;&#xA;&lt;li&gt;if you fly any slower, the maximum lift that the wing can provide will be insufficient to maintain altitude. Descent or the aircraft will stall. &lt;/li&gt;&#xA;&lt;li&gt;if you fly any higher and you will be too fast and too slow at the same time. &lt;/li&gt;&#xA;&lt;li&gt;if you turn, you increase the wing loading, thereby increasing the minimum speed needed to create the required lift. Also the outer wing will easily exceed the maximum speed while at the same time the inner wing is below stall speed. This can quickly develop into a spin. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since accurate knowledge of engine performance, drag and wing characteristics of the aircraft is needed, there is not a simple formula to derive the maximum altitude for an aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Apart from the aircraft performance related limitations above there is a certified maximum operating altitude for the pressurized cabin. This takes into account the structural properties of the hull (pressure difference between inside and outside) and the achievable emergency descent rate in case of a depressurization event.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="8346" LastEditDate="2017-06-25T12:46:20.247" LastActivityDate="2017-06-25T12:46:20.247" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9196" PostTypeId="2" ParentId="9182" CreationDate="2014-10-17T16:14:27.430" Score="6" Body="&lt;p&gt;I think the answer is no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think about V&lt;sub&gt;1&lt;/sub&gt; as primarily based on runway length, it is certainly possible for an aircraft to easily reach V&lt;sub&gt;r&lt;/sub&gt; long before reaching the &quot;point of no return&quot; as far as stopping distance is concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you must also consider the meaning of V&lt;sub&gt;r&lt;/sub&gt;. This is when the aircraft is going to rotate. After rotation and leaving the ground, the distance required to still stop on that same runway increases significantly.  For this reason, maximum V&lt;sub&gt;1&lt;/sub&gt; is generally considered to be V&lt;sub&gt;r&lt;/sub&gt; (see &lt;a href=&quot;https://www.airliners.net/forum/viewtopic.php?t=750003&quot; rel=&quot;nofollow noreferrer&quot;&gt;this discussion&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In large aircraft, rejecting a takeoff after leaving the ground is generally discouraged, unless the pilot feels that the plane could be uncontrollable. It's much safer to continue the takeoff and fly for a normal approach. However, &lt;a href=&quot;http://avherald.com/h?article=471583da&quot; rel=&quot;nofollow noreferrer&quot;&gt;it can happen&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In smaller aircraft, it's more reasonable for the aircraft to take off and then land safely (I'm thinking a C172 on one of the low density altitude runways you linked to).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2019-05-04T22:13:20.500" LastActivityDate="2019-05-04T22:13:20.500" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="9197" PostTypeId="2" ParentId="9180" CreationDate="2014-10-17T16:27:54.200" Score="1" Body="&lt;p&gt;Yes, it is possible to cobble together some sort of headphone system, but another consideration is whether or not these unapproved systems will damage the aircraft radio system. Audio systems are designed with certain impedance values, plugging in non-aircraft headphones could burn out the audio system. Hopefully the audio panels are robust enough to handle other headsets, but why take that chance?&#xA;FAA TSO-C139 addresses aircraft audio systems, and most aircraft headsets meet that specification. There continues to be confusion about aircraft headsets that do not meet that specification, especially in air transport where pilots can bring their own non-approved headsets into the cockpit.&#xA;My recommendation is to buy, borrow or rent the approved headsets for aircraft. If you bring back an airplane that was damaged because of plugging in the wrong headsets, you would have been better off just buying an inexpensive approved headset.  &lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2014-10-17T16:27:54.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9198" PostTypeId="2" ParentId="3015" CreationDate="2014-10-17T16:32:24.747" Score="7" Body="&lt;p&gt;Heavy jet aircraft do not have keys. You can enter the cockpit door which do not have locks, start up the APU - a small jet engine in the tail - to give you power and air. Then start the main engines all of which just have toggle or push button switches. It would be very easy to steal if you knew the systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aircraft mechanic for 40 years I feel there is a severe threat for this to happen. I invented a small tool that would keep this from happening but no one is interested as of yet. There is a pilot who attempted to steal a commerial aircraft on 7-17-2012. I have contacted the TSA, FAA, Professional Pilots ass. with my concerns and the answer to the issue. I guess it will just have to happen before anyone listens!&lt;/p&gt;&#xA;" OwnerUserId="3959" LastEditorUserId="19" LastEditDate="2014-10-17T16:54:55.563" LastActivityDate="2014-10-17T16:54:55.563" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9199" PostTypeId="2" ParentId="9183" CreationDate="2014-10-17T17:41:40.947" Score="6" Body="&lt;p&gt;you can make a brick take off without flaps,  if you put enough power behind it, and those jets have enough power,  (as long as the runway is long enough for those particular hunks of metal)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a good question can be added on,  how long of a runway does a 'xxx' need with half load,  with empty load, with full load and fuel,  with broken flaps.&lt;/p&gt;&#xA;" OwnerUserId="3961" LastActivityDate="2014-10-17T17:41:40.947" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9200" PostTypeId="2" ParentId="9052" CreationDate="2014-10-17T17:48:45.533" Score="2" Body="&lt;p&gt;and then the obvious one... you retract your flaps so you don't keep hitting your head on the flap when you are bent over walking around your plane  :)&lt;/p&gt;&#xA;" OwnerUserId="3961" LastActivityDate="2014-10-17T17:48:45.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9201" PostTypeId="1" AcceptedAnswerId="9205" CreationDate="2014-10-17T18:26:59.810" Score="22" ViewCount="5509" Body="&lt;p&gt;In her 1970 song &quot;This Flight Tonight&quot;, Joni Mitchell &lt;a href=&quot;https://jonimitchell.com/music/song.cfm?id=62&quot; rel=&quot;nofollow noreferrer&quot;&gt;sings&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm drinking sweet champagne&lt;br&gt;&#xA;  Got the headphones up high&lt;br&gt;&#xA;  Can't numb you out&lt;br&gt;&#xA;  Can't drum you out of my mind&lt;br&gt;&#xA;  They're playing Goodbye baby, Baby Goodbye&lt;br&gt;&#xA;  Ooh ooh love is blind&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Sony Walkman first came out near the end of that decade. So what was Joni listening to on that fateful flight?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I will award a 100 point bonus to anyone who can identify the plane she was on in the song based on the lyrics.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="2556" LastEditorUserId="2556" LastEditDate="2019-07-08T13:16:14.627" LastActivityDate="2019-07-08T13:16:14.627" Title="What was the inflight entertainment in the early seventies?" Tags="&lt;aviation-history&gt;&lt;inflight-entertainment&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9202" PostTypeId="2" ParentId="9201" CreationDate="2014-10-17T18:40:18.577" Score="11" Body="&lt;p&gt;I remember flying on planes in the late 70's/early 80's, where there were headphone jacks built into the armrests.  But they weren't electronic jacks; the headphones were connected by rubber tubing, and the speakers were actually in the armrest, so the sound was conducted up the rubber tubing to the earpiece.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It made the headphones extremely cheap:  they were just molded plastic and rubber tubing.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-10-17T18:40:18.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9204" PostTypeId="1" AcceptedAnswerId="9218" CreationDate="2014-10-17T19:56:35.230" Score="9" ViewCount="5722" Body="&lt;p&gt;I have noticed that on a lot (all?) Airbus cockpits, there are these &quot;things&quot; (for lack of a better term) under the panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have highlighted them in this picture of an A340 cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://img.ourl.ca/a330.png&quot; alt=&quot;A340 Cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.210" LastActivityDate="2014-10-20T23:14:42.847" Title="What is this component in an Airbus cockpit?" Tags="&lt;airbus&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9205" PostTypeId="2" ParentId="9201" CreationDate="2014-10-17T20:01:44.280" Score="23" Body="&lt;p&gt;During that time, the in-flight entertainment mostly available on flights was radio&lt;sup&gt;1&lt;/sup&gt; and/or TVs. Although it was not on all flights. Oops, that is true even today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radios may or may not have channels. If they had, there was a knob on the armrest, next to headset jacks, to switch channels. The headsets were pneumatic units like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ywin4.jpg&quot; alt=&quot;headset&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The in-flight movies were shown using one or more common CRT TVs mounted on ceilings or walls and audio could be heard using the headsets. The &lt;a href=&quot;http://www.historyofpia.com/firsts.htm&quot; rel=&quot;noreferrer&quot;&gt;first time a movie was shown on an international flight&lt;/a&gt; was in 1962 by &lt;a href=&quot;http://en.wikipedia.org/wiki/Pakistan_International_Airlines&quot; rel=&quot;noreferrer&quot;&gt;PIA&lt;/a&gt;. It was more like the picture below but instead of LCD monitors, there were CRTs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TjHzD.jpg&quot; alt=&quot;tv&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In mid-seventies, &lt;a href=&quot;http://en.wikipedia.org/wiki/Braniff_International_Airways&quot; rel=&quot;noreferrer&quot;&gt;Braniff Airways&lt;/a&gt; was the first airline to offer &lt;a href=&quot;http://www.braniffpages.com/1965/1965.html&quot; rel=&quot;noreferrer&quot;&gt;video games in-flight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By 1979, electronic headsets replaced their pneumatic counterparts, which improved audio quality.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has a &lt;a href=&quot;http://en.wikipedia.org/wiki/In-flight_entertainment#History&quot; rel=&quot;noreferrer&quot;&gt;detailed article&lt;/a&gt; about the history of in-flight entertainment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1971, TRANSCOM developed the 8mm film cassette. Flight attendants&#xA;  could now change movies in-flight and add short subject programming.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In the late 1970s and early 1980s, CRT-based projectors began to&#xA;  appear on newer widebody aircraft, such as the Boeing 767.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://skift.com/2014/01/09/a-brief-history-of-in-flight-entertainment-from-projectors-to-ipads/&quot; rel=&quot;noreferrer&quot;&gt;This website&lt;/a&gt; has nice slideshow about the history.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sup&gt;1&lt;/sup&gt;: Not actually a radio, but recorded audio&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-02-27T15:02:12.010" LastActivityDate="2015-02-27T15:02:12.010" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="9206" PostTypeId="2" ParentId="9204" CreationDate="2014-10-17T20:08:09.287" Score="13" Body="&lt;p&gt;Since Airbus planes use a sidestick instead of the traditional center yoke, they use the space where the yoke would be to include a fold out table instead. You can see a laptop on &lt;a href=&quot;http://www.airliners.net/photo/Thomas-Cook-Airlines/Thomas-Cook-Airlines/1243399/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;one here&lt;/a&gt;. The A380 version also has a keyboard. This is used to interface with the onboard systems and &lt;a href=&quot;http://www.airbus.com/support/publications/?eID=maglisting_push&amp;amp;tx_maglisting_pi1%5BdocID%5D=17467&quot; rel=&quot;nofollow noreferrer&quot;&gt;input information&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rLdZ3.jpg&quot; alt=&quot;A380 Cockpit&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-17T20:14:05.283" LastActivityDate="2014-10-17T20:14:05.283" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9207" PostTypeId="2" ParentId="9204" CreationDate="2014-10-17T20:31:52.627" Score="7" Body="&lt;p&gt;Are you talking about this area?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5QOHI.jpg&quot; alt=&quot;keyboard in&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a pull out keyboard, which is part of &lt;a href=&quot;http://en.wikipedia.org/wiki/Electronic_flight_bag&quot; rel=&quot;noreferrer&quot;&gt;Electronic flight bag (EFB)&lt;/a&gt;. It is part of a standard laptop computer. However, its integrated Keyboard Cursor Control Unit (KCCU) can interact with the cockpit screens. The full-size keyboard felt substantial and, in the paperless cockpit, will greatly ease the tasks of data and text entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KYkeA.jpg&quot; alt=&quot;keyboard out&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-10-17T20:31:52.627" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9209" PostTypeId="2" ParentId="809" CreationDate="2014-10-17T21:59:30.620" Score="5" Body="&lt;p&gt;If you have two radios it is a good idea to monitor 121.5 on your second radio.  You can set the volume slightly lower than the primary radio you are listening to.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing this allows you to hear ELT's (remember the old ELT's are not monitored by satellites anymore - just the 406 elt's)  So if you hear an ELT you can notify ATC and they can investigate it.  This has helped more than one downed pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if you are flying VFR and nearing a TFR, or other restricted airspace, you may get a call in the blind on 121.5 giving your position, direction of flight, and altitude readout along with a warning that you are about to enter, or have entered restricted airspace.  This call may keep you from having a violation.&lt;br&gt;&#xA;If you are in the restricted airspace, the call will include a direction to exit the airspace and usually a frequency to contact for directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We all need to help and watch out for each other.  If you do this long enough you will make a call on 121.5 in error.  At that time all of the people who never make mistakes will point it out to you.  Just remember, by monitoring 121.5 you can keep yourself stay out of trouble and help someone else who has experienced trouble.&lt;/p&gt;&#xA;" OwnerUserId="3965" LastActivityDate="2014-10-17T21:59:30.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9210" PostTypeId="2" ParentId="9201" CreationDate="2014-10-17T22:10:08.853" Score="11" Body="&lt;p&gt;There would be a number of channels of pre-recorded 'radio'-type shows, typically 5 or 6 if I recall correctly, such as current affairs, comedy, classical music, easy-listening &amp;amp; pop/rock, plus the movie channel or channels.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines charged a nominal rental for the headsets, while others provided them in the plastic-wrapped 'travel pack' of blanket and pillow/cushion.  Either way, they were gathered up before landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The earliest headsets were pneumatic, but later there were electronic ones, albeit with connectors that were pretty much exclusive to airline travel, to discourage them going astray.&lt;/p&gt;&#xA;" OwnerUserId="1715" LastEditorUserId="1715" LastEditDate="2014-10-18T16:07:47.167" LastActivityDate="2014-10-18T16:07:47.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9211" PostTypeId="1" AcceptedAnswerId="9212" CreationDate="2014-10-17T22:39:00.850" Score="16" ViewCount="2954" Body="&lt;p&gt;In an answer given to &lt;a href=&quot;https://aviation.stackexchange.com/questions/537/how-can-i-politely-remind-atc-that-im-waiting-for-instructions-or-clearance&quot;&gt;How can I politely remind ATC that I&amp;#39;m waiting for instructions or clearance?&lt;/a&gt; by @Mark, he quoted part of AIM regs:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;4-3-14. Communications&lt;/p&gt;&#xA;&lt;p&gt;a. Pilots of departing aircraft should communicate with the control tower on the appropriate ground control/clearance delivery frequency prior to starting engines to receive engine start time, taxi and/or clearance information. Unless otherwise advised by the tower, remain on that frequency during taxiing and runup, then change to local control frequency when ready to request takeoff clearance.&lt;/p&gt;&#xA;&lt;p&gt;NOTE- Pilots are encouraged to monitor the local tower frequency as soon as practical consistent with other ATC requirements.&lt;/p&gt;&#xA;&lt;p&gt;REFERENCE- AIM, Automatic Terminal Information Service (ATIS), Paragraph 4-1-13.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;b. The tower controller will consider that pilots of turbine-powered aircraft are ready for takeoff when they reach the runway or warm-up block unless advised otherwise.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I have bolded paragraph b because that is what I am asking about here. Why is the tower controller to consider turbine-powered aircraft to be &amp;quot;ready for takeoff when they reach the runway&amp;quot;?&lt;/p&gt;&#xA;&lt;p&gt;Why are non-turbine engines (piston?) not ready?&#xA;What does this paragraph cause the tower to not have to do?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-10-30T10:25:49.663" Title="Why are turbine-powered aircraft &quot;considered ready for takeoff&quot;?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;aim&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9212" PostTypeId="2" ParentId="9211" CreationDate="2014-10-17T23:18:09.220" Score="19" Body="&lt;p&gt;Piston aircraft require a run up, in which the pilot sets the power to a specified RPM, in order to check proper functioning of a variety of systems, and to ensure that the oil is warmed up to a specified temperature. Among the systems to be tested are carborator heat (for normally-aspirated engines), magneto operation, alternate air (for fuel-injected engines), hydraulic systems, and propeller governor (for variable-pitch props). In an aircraft with a hydraulically-activated variable pitch prop, the prop is &quot;exercised&quot; by varying the pitch, which allows the cold motor oil in the prop governor to mix with the warm oil in the engine sump, to bring the entire lubrication system's oil temperature up into the green arc. During the runup, the vacuum system is checked to ensure that enough vacuum pressure is provided to critical instruments. Lastly, a grounding check is made with the magnetos, to make sure that the magneto electrical system is properly grounded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Performing a run up at the ramp would prove dangerous to people and aircraft if not tied down and due to FOD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally turbine warmup occurs pretty quickly after startup and during taxi. They are usually ready to go at the ramp.&lt;/p&gt;&#xA;" OwnerUserId="266" LastEditorUserId="1961" LastEditDate="2014-10-27T14:09:43.107" LastActivityDate="2014-10-27T14:09:43.107" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9213" PostTypeId="2" ParentId="809" CreationDate="2014-10-18T01:26:38.040" Score="4" Body="&lt;p&gt;121.5 MHz is the international civilian distress frequency. It has been designated for emergency communication by an international agreement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO Annex 10, Volume V, § 4.1.3.1.1 states that frequency 121.5 MHz “shall be used only for genuine emergency purposes” broadly covering the following activities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The handling of an emergency situations;&lt;/li&gt;&#xA;&lt;li&gt;air-ground communication with aircraft with airborne equipment failure;&lt;/li&gt;&#xA;&lt;li&gt;search and rescue operations and the operation of emergency locator transmitters (ELTs); and&lt;/li&gt;&#xA;&lt;li&gt;air policing/interception action. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-10-18T01:26:38.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9215" PostTypeId="2" ParentId="1210" CreationDate="2014-10-18T08:55:30.407" Score="22" Body="&lt;p&gt;&lt;strong&gt;ICAO&lt;/strong&gt; is the &lt;a href=&quot;http://www.icao.int/about-icao/Pages/default.aspx&quot;&gt;International Civil Aviation Organization&lt;/a&gt;, a specialized agency of United Nations. It was created after the &lt;a href=&quot;http://www.icao.int/publications/Documents/7300_orig.pdf&quot;&gt;Convention on International Civil Aviation&lt;/a&gt; (the Chicago Convention) of 1944 was ratified in 1947. The purpose of ICAO is according to the convention:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;WHEREAS the future development of international civil aviation can greatly help to create and preserve friendship and understanding among the nations and peoples of the world, yet its abuse can become a threat to the general security; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;WHEREAS it is desirable to avoid friction and to promote that co-operation between nations and peoples upon which the peace of the world depends;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;THEREFORE, the undersigned governments having agreed on certain principles and arrangements in order that international civil aviation may be developed in a safe and orderly manner and that international air transport services may be established on the basis of equality of opportunity and operated soundly and economically;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Have accordingly concluded this Convention to that end.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Within ICAO, the 191 Member States and a number of global aviation organizations work together to develop international Standards and Recommended Practices (SARPs). These SARPs are the reference for states developing their national civil aviation regulations which are legally enforcible. This is an important aspect: ICAO SARPs are not legally binding by themselves, they form the basis of national regulations which have legal status. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this way civil aviation regulations are harmonized all over the world, with slight differences based on the actual implementation in national regulations. These local differences are then reported back to ICAO and published.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CAA&lt;/strong&gt; is the Civil Aviation Authority. This is a generic term used in many countries, notably the UK and China. A CAA is a national regulatory body responsible for aviation. The CAA implements the ICAO SARPs in national legislation and is responsible for regulatory oversight. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FAA&lt;/strong&gt; is the Federal Aviation Administration. As the Civil Aviation Authority of the USA, it is responsible for establishing aviation regulations in the US. These are known as FARs (Federal Aviation Regulations).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to its regulatory role, the FAA is also responsible for Airspace and Air Traffic Management, maintenance of Air Navigation Facilities infrastructure and has an active role in Research and Development of aviation related systems and technologies.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;JAA&lt;/strong&gt; were the &lt;a href=&quot;http://www.jaa.nl/introduction/introduction.html&quot;&gt;Joint Aviation Authorities&lt;/a&gt;, a co-operation of most European (EU and non-EU) civil aviation regulatory authorities. It was not a regulatory body itself, the member authorities were responsible for the regulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally started as the Joint Airworthiness Authorities in 1970 its objectives were to produce common certification standards for large aircraft and aircraft engines to facilitate a European aviation manufacturing industry (Airbus). Over time, the scope was extended to included aircraft operations, maintenance, licensing and certification/design standards for all classes of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the creation of EASA (see below) in 2002, the EU members transferred the airworthiness regulations away from the JAA. Over time, EASA became responsible for operations and licensing as well.  In 2009 the JAA system was disbanded. Only the training organisation (JAA-TO) remains, it mainly provides courses for CAA staff of European countries.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EASA&lt;/strong&gt; is European Aviation Safety Agency. Created in 2002 by the European Commission, EASA took over the functions of the Joint Aviation Authorities of the EU countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The responsibilities of EASA include drafting of aviation safety legislation and providing technical advice to the European Commission and to the EU Member States, airworthiness and type certification of aircraft and aircraft parts for aircraft operating in the EU, approval of aircraft design organisations world-wide and of production and maintenance organisations inside and outside of the EU.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since its creation, the competences of EASA have gradually expanded. This process is still going on. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-18T08:55:30.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9216" PostTypeId="2" ParentId="9182" CreationDate="2014-10-18T10:36:46.087" Score="4" Body="&lt;p&gt;Simply no &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotation comes always after decision :) &lt;/p&gt;&#xA;" OwnerUserId="3971" LastEditorUserId="19" LastEditDate="2014-10-18T11:25:57.167" LastActivityDate="2014-10-18T11:25:57.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9218" PostTypeId="2" ParentId="9204" CreationDate="2014-10-18T15:40:32.093" Score="13" Body="&lt;p&gt;The centre bit is the pull out mechanism for the table, the two bits either side are fold down footrests.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nhzDn.jpg&quot; alt=&quot;Picture found via google image search&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-18T15:40:32.093" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9219" PostTypeId="2" ParentId="9211" CreationDate="2014-10-18T16:09:11.803" Score="4" Body="&lt;p&gt;The tower controller can plan that the aircraft will be ready to line up and depart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is important in sequencing the traffic at busy airports. If your watching a number of aircraft taxi out to the hold, its likely (dependant on the aerodrome layout) that the piston aircraft will have a number of run up checks to do, which can take a few minutes. Whilst a jet aircraft should be ready to depart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certainly in commercial jet ops it's more efficient to be ready to go by the time you reach the hold. Any time spent on the ground decreases the effective utilisation of the aircraft. Controllers are normally aware how keen pilots are to get airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: Jet engines also require a warm up time, this is normally a minimum oil temperature which must be achieved prior to setting takeoff thrust. There is normally no special procedures, warm up being accomplished by the engines being used to taxi the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-18T16:09:11.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9220" PostTypeId="2" ParentId="9144" CreationDate="2014-10-18T16:22:24.227" Score="5" Body="&lt;p&gt;Engine thrust is measured in flight by EPR - Engine Pressure Ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EPR is the ratio of the turbine exhaust pressure divided by the pressure measured at the fan or inlet. Indeed this is the measure used for a number of engines for setting thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More detailed airborne testing of engines is done during development, most manufacturers have airborne testbeds. The parameters recorded here probably measure in the hundreds or even thousands...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uvz9x.gif&quot; alt=&quot;Rolls Royce B747 Testbed - image from Flight Global&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="412" LastEditorUserId="412" LastEditDate="2014-10-18T17:20:14.970" LastActivityDate="2014-10-18T17:20:14.970" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9221" PostTypeId="2" ParentId="9201" CreationDate="2014-10-18T19:44:07.203" Score="4" Body="&lt;p&gt;This is slightly off-topic because it is more about video than sound, however &lt;a href=&quot;http://www.letsflycheaper.com/blog/in-flight-entertainment-a-quick-look-at-its-history/&quot; rel=&quot;nofollow&quot;&gt;In Flight Entertainment, a Quick Look at its History&lt;/a&gt; says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The popularity of in-flight entertainment didn’t really take off until&#xA;  &lt;strong&gt;1960 with the invention of a smaller, more portable film playing&#xA;  system that would play smaller 16 mm reels&lt;/strong&gt;.  Soon after, the invention&#xA;  of &lt;strong&gt;the pneumatic headset&lt;/strong&gt; would finally resolve the problem of being&#xA;  able to hear over the loud cabin noises. TWA became the first major&#xA;  airline to use the new system boosting them to become the world’s&#xA;  premiere airline to travel on.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;The addition of the 8 mm cassette in 1971 made in-flight entertainment&#xA;  a more efficient process, mainly for the flight attendants who could&#xA;  simply change the film during the flight. The video cassette&lt;/strong&gt; would&#xA;  dominate the way passengers viewed in-flight films until the invention&#xA;  of the DVD which would later become the primary source of all&#xA;  in-flight movies.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Throughout the &lt;strong&gt;late 1970s and into the early 1980s, the CRT based&#xA;  projectors&lt;/strong&gt; began appearing on some wide body airliners. The CRT&#xA;  projector used electric beams of colored light that would beam films&#xA;  onto a fluorescent screen. The CRT was able to display a larger,&#xA;  clearer picture using both video cassettes and laser discs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="556" LastActivityDate="2014-10-18T19:44:07.203" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9222" PostTypeId="2" ParentId="9066" CreationDate="2014-10-18T21:54:16.903" Score="43" Body="&lt;p&gt;&lt;strong&gt;In a nutshell&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A compressor blade works best in subsonic flow. Supersonic flow introduces additional drag sources which should be avoided if efficiency is important. Thus, the intake has to slow down the air to a Mach number between 0.4 and 0.5. Note that the high circumferential speed of a large fan blade will still mean that its tips work at around Mach 1.5, but the subsequent compressor stages will operate in subsonic conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A scramjet is possible with fuels with supersonic &lt;a href=&quot;http://en.wikipedia.org/wiki/Flame_speed&quot; rel=&quot;noreferrer&quot;&gt;flame front speeds&lt;/a&gt; and rapid mixing of fuel and air. If the engine would burn regular kerosene, the flame would be blown out like a candle if the internal airspeed would be supersonic, and even if &lt;a href=&quot;http://en.wikipedia.org/wiki/Flame_holder&quot; rel=&quot;noreferrer&quot;&gt;flame holders&lt;/a&gt; keep the flame in place, most combustion would take place only after the fuel-air mixture has left the engine due to the slow mixing of kerosene and air. By using hydrogen, a stable combustion can be achieved even in supersonic flow. Due to the high flight speeds, compression is possible by a cascade of shocks, so no moving turbomachinery is needed in ramjets and scramjets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Background: Maximum heating of air&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All jets decelerate air in their intake in order to increase air pressure. This compression heats the air, and in order to achieve a combustion which produces thrust, this heating must be restricted. &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a224584.pdf&quot; rel=&quot;noreferrer&quot;&gt;If air is heated above approx. 6,000° K&lt;/a&gt;, adding more energy will result in dissociation of the gas with little further heat increase. Since thrust is produced by expanding air through heating, burning air that enters the combustion process already at 6,000° K will not achieve much thrust. If the air enters the intake at Mach 6, it must not be decelerated below approx. Mach 2 to still achieve combustion with a meaningful temperature increase - that is why scramjets are used in hypersonic vehicles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Full disclosure: Oxygen starts to dissociate already between 2,000° and 4,000° K, depending on pressure, while Nitrogen will dissociate mainly above 8,000° K. The 6,000° K figure above is a rough compromise for the boundary where adding more energy starts to make less and less sense. Of course, even a 6,000° K flame temperature is a challenge for the materials of the combustion chamber, and ceramics with &lt;a href=&quot;http://www.me.umn.edu/labs/tcht/measurements/what.html&quot; rel=&quot;noreferrer&quot;&gt;film cooling&lt;/a&gt; are mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equation for the stagnation temperature $T_0$ of air shows how important the flight speed $v$ is: $$T_0 = T_{\infty} \cdot \frac{v^2}{c_p} = T_{\infty} \cdot \left(1 + \frac{\kappa - 1}{2}\cdot Ma^2 \right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T_{\infty}$ is the ambient temperature, $c_p$ the specific heat at constant pressure and $\kappa$ the ratio of specific heats. For two-atomic gases (like oxygen and nitrogen), $\kappa$ is 1.405. Temperature increases with the square of flight speed, so at Mach 2 the factor of heat increase over ambient is only 3.8, while at Mach 6 this becomes 26.3. Even at 220° K air temperature, the air will be heated to 5,800° K when it is ideally compressed in case of a hypersonic vehicle traveling at Mach 6. Note that real compression processes will heat air even more due to friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Compression with shocks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supersonic flow is slowed down by a pressure rise along the flow path. Since no &quot;advance warning&quot; of what is coming is possible, this pressure rise is sudden: Pressure jumps from a fixed value ahead to a higher, fixed value past the jump. This is called a shock. The energy for the pressure rise is taken from the kinetic energy of the air, so past the shock all other parameters (speed, density and temperature) take on new values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x7ukp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x7ukp.jpg&quot; alt=&quot;F-16 air intake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 air intake (picture &lt;a href=&quot;http://i1347.photobucket.com/albums/p701/Engines101/F-16_Fighting_Falcon_air_intake_zps1295a2f8.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest shock is a straight shock. This can be found at the face of pitot intakes like the one of the F-16 (see the picture above) in supersonic flight. More common are oblique shocks which are tilted according to the Mach number of the free flow. They happen on leading and trailing edges, fuselage noses and contour changes in general: Whenever something bends the airflow due to its displacement effect, the mechanism for this bending of the flowpath is an oblique shock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TYi8X.png&quot; alt=&quot;straight and oblique shock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;straight and oblique shock (own work)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The index 1 denotes conditions ahead of the shock, and 2 those downstream of the shock. For weak straight shocks the product of the speed ahead of the shock $v_1$ and the speed past the shock $v_2$ equals the square of the speed of sound: $$v_1\cdot v_2 = a^2$$&#xA;If $Ma_1 &amp;gt; 1$, then $Ma_2$ must be smaller than 1, so the flow is always decelerated to subsonic speed by a straight shock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same equation works for the normal speed component $v_n$ ahead and past a weak oblique shock: $$v_{1n}\cdot v_{2n} = a^2$$&#xA;Note that the tangential component $v_t$ is unaffected by the shock! Only the normal component is reduced. Now the speed $v_2$ is still supersonic, but lower than $v_1$, so a weak oblique shock produces a modest increase of pressure, density and temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/machang.html&quot; rel=&quot;noreferrer&quot;&gt;The angle of the oblique shock wave is determined by the Mach number ahead of the shock.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Supersonic intakes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weak shocks are desired, because they produce only small losses due to friction. Pitot intakes with their single, straight shocks work well at low supersonic speeds, but incur higher losses at higher Mach numbers. As a rule of thumb, a pitot intake is the best compromise at speeds below Mach 1.6. If the design airspeed is higher, more complex and heavier intakes are needed to decelerate the air efficiently. This is done by a sequence of weak, oblique shocks and by means of a wedge intake. The picture below shows the intake of the supersonic &lt;a href=&quot;http://www.concordesst.com&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; airliner:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6HmMh.jpg&quot; alt=&quot;Concorde intake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde intake (picture &lt;a href=&quot;http://s991.photobucket.com/user/riconc1/media/Concorde/ShockComplex.jpg.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gradually increasing the angle of the wedge is causing a cascade of ever steeper, oblique shocks which gradually decelerate the air. The design goal is to position this cascade of shocks caused by the wedge on top such that they hit the lower intake lip. This is done by a moveable contour of the upper intake geometry and/or the lip. The goal is to achieve a uniform speed over the intake cross section and not to waste any of the compressed air to the flow around the intake. See the picture of the Eurofighter intake below for an example of a moveable intake lip (which admittedly is mainly for increasing the capture area at low speed and for avoiding flow separation even with a small intake lip radius).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8LI4I.jpg&quot; alt=&quot;Eurofighter intake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eurofighter intake (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/1/1b/2010-06-11_Eurofighter_Luftwaffe_31+16_EDDB_02.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the air has entered the intake, it is only mildly supersonic and can be further decelerated by a final, straight shock at the narrowest point of the intake. After that point, the intake contour is gradually widened, such that the air decelerates further without separation. To achieve this, a very even flow across the intake area is mandatory, and even the slight disturbance caused by the boundary layer of anything which is ahead of the intake must be avoided. This is achieved by a splitter plate which is clearly visible in the pictures of the F-16 and Eurofighter intakes. The splitter plate of the Eurofighter intake is even perforated to suck away the early boundary layer there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deceleration of the intake flow results in a significant pressure rise: In case of the Concorde at Mach 2.02 cruise, the intake caused a pressure rise by a factor of more than 6, so the engine compressor had to add &quot;only&quot; a factor of 12, such that the pressure in the combustion chamber of the four &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593&quot; rel=&quot;noreferrer&quot;&gt;Olympus 593&lt;/a&gt; engines was 80 times that of the ambient pressure (admittedly, this ambient pressure was only 76 mbar in the cruise altitude of 18 km).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This pressure increase means that a supersonic intake must be built like a pressure vessel, and the rectangular face of the intake must quickly be changed to a round cross section downstream to keep the mass of the intake structure low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Intakes at higher speed&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going faster means the intake pressure recovery increases with the square of flight speed: In case of the SR-71 intake at Mach 3.2, the pressure at the engine face was already almost 40 times higher than the ambient pressure. Now it becomes clear that going faster than Mach 3.5 does away with the need for a turbocompressor: At these speeds a properly designed intake can achieve enough compression by itself for the combustion to produce enough thrust, and going above Mach 5 will need restraint in slowing down the intake flow in order to have enough temperature margin for combustion, requiring supersonic flow in the combustion chamber.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-04-30T17:49:50.073" LastActivityDate="2016-04-30T17:49:50.073" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9223" PostTypeId="1" AcceptedAnswerId="9231" CreationDate="2014-10-19T07:52:08.467" Score="9" ViewCount="3622" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Runway#Pavement&quot;&gt;Wikipedia&lt;/a&gt; list a number of runway pavement. For specific airports, the choice is obvious (e.g. ice, snow). But there are few pavement I cannot figure out how to decide which one use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why an airport would choose asphalt over concrete or bitumeous asphalt for the runway pavement? What are the reason for the choice?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2019-03-11T19:08:44.577" Title="How is the runway pavement chosen?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9224" PostTypeId="2" ParentId="9052" CreationDate="2014-10-19T08:08:40.077" Score="4" Body="&lt;p&gt;On larger aircraft it would be standard operating procedure to retract the flaps after landing. This is to ensure the crew taking over from you are presented with an aircraft in the correct state in accordance with company SOPs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps could easily be damaged by ground crew loading and unloading. Also it would be difficult to refuel the aircraft with the flaps/slats extended (Larger Boeing types have the refuel system located at the leading edge underneath a wing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are occasions when you would leave the flaps extended, during operations in heavy snow for example - retracting contaminated surfaces may cause damage.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-19T08:08:40.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9225" PostTypeId="1" AcceptedAnswerId="9229" CreationDate="2014-10-19T09:43:37.827" Score="10" ViewCount="585" Body="&lt;p&gt;Regarding this excellent question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9201/what-was-the-inflight-entertainment-in-the-early-seventies&quot;&gt;What was the inflight entertainment in the early seventies?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a mention that the &quot;TRANSCOM 8mm film cassette&quot; (that was film-film, ie the plastic stuff you can see-through, not video tape) was used on some planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've found all the references to this on the WWW &lt;strong&gt;are poor references copying each other&lt;/strong&gt; with no details (but I may be missing something).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Can anyone find literally an image of film-projector technology being used for in-flight entertainment?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are there any specific references / image examples to the &quot;TRANSCOM 8mm film cassette&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What year was about the last year film projection technology was used (if it was ever used?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Or indeed -- memories of these things, even better! Cheers.&lt;/p&gt;&#xA;" OwnerUserId="3288" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-03-20T12:57:00.960" Title="Are there any documented example usages of film (ie, film film, not video or digital) for in-flight entertainment?" Tags="&lt;airliner&gt;&lt;aviation-history&gt;&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9226" PostTypeId="2" ParentId="9144" CreationDate="2014-10-19T09:51:22.750" Score="6" Body="&lt;p&gt;VectorVictor gives the right answer for jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for propeller aircraft this is really hard, and in the end only the difference between drag and thrust can be measured. By measuring the brake power of the static engine and the drag of the aircraft in a windtunnel, some data points can be acquired which help in calculating what the real thrust in flight could have been.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right, in the end it is impossible to produce a precise measurement of thrust. The most important part of the measurement is actually a precise definition of what thrust is: How do you account for the increased friction drag in the propeller slipstream? Is cooling drag part of the airframe drag, or should it reduce thrust? Measuring thrust is foremost an exercise in precise, meticulous bookkeeping. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-19T09:51:22.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9227" PostTypeId="2" ParentId="9188" CreationDate="2014-10-19T11:41:34.877" Score="17" Body="&lt;p&gt;The maximum altitude is limited by a number of factors, and the one which counts depends on the particular aircraft. These are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Engine power output&lt;/strong&gt;. Airbreathing engines produce less power the higher they operate due to decreasing density with altitude. In reciprocating engines, this can be overcome with turbocharging, and dedicated high-altitude piston engines use triple-stage turbochargers with intercoolers. In dedicated high-altitude designs, the engine is the smallest part of the propulsion package, most is cooling and ducting. The propeller has to be matched to the low density at high altitude, increasing in diameter for operation in low density air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Combustion chamber pressure&lt;/strong&gt;: The altitude limit of jet engines is mostly determined by the pressure ratio of the intake and the compressor. If this pressure drops below the minimum for sustained combustion, the engine will flame out. Since jet engines are in principle a big turbocharger where the piston engine has been replaced by a combustion chamber, this combustion chamber becomes the weak link.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Wing loading&lt;/strong&gt;: The lower the wing loading, the lower air density can become before a wing will fail to produce enough lift. If the engines produce enough power for sustained flight (electric propulsion with solar panels, for example), the limit becomes the structural integrity of the light structure. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/7691/how-high-can-propeller-airplanes-fly/7693#7693&quot;&gt;this answer&lt;/a&gt; for an applied example.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Maximum flight Mach number&lt;/strong&gt;: For supersonic aircraft, the limit is given by a combination of wing loading and maximum speed. The faster the aircraft can fly, the lower air density can be. In most cases, the speed limit is given by intake efficiency, because &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;intakes need to be optimized for their flight Mach number&lt;/a&gt;, and thermal limits due to airframe heating. Note that a fast aircraft with lift reserves can perform a pull-up at altitude, converting kinetic energy into potential energy (aka altitude), so the instationary maximum altitude could be several 1000 m above the stationary altitude limit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aerodynamic efficiency&lt;/strong&gt;: This is the only factor where I can give you a simple equation, and it is determined by the aerodynamic quality of the wing and its airfoil. It applies to subsonic flight where an &lt;a href=&quot;https://aviation.stackexchange.com/questions/8016/what-is-a-high-speed-stall/8020#8020&quot;&gt;increase above a critical flight Mach number will reduce lift&lt;/a&gt;. Expressed as the minimum air density $\rho_{min}$, this is $$\rho_{min} = \frac{2\cdot m\cdot g}{(Mach^2 \cdot c_L)_{max}\cdot a^2\cdot S}$$&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Here we find again wing loading $\frac{m}{S}$ as a factor, but also the maximum of the product of the square of the flight Mach number $Ma^2$ and the lift coefficient $c_L$. $a$ is the speed of sound. A good value of $Mach^2 \cdot c_L$ is 0.4, and it needs supercritical airfoils to be achieved. Use this number for modern designs and you will get a pretty accurate answer if engine thrust is sufficient. For older designs, values between 0.3 and 0.35 are a better fit. Very early designs with poor aerodynamics like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Westland_Welkin&quot; rel=&quot;noreferrer&quot;&gt;Westland Welkin&lt;/a&gt; would only achieve a $Mach^2 \cdot c_L$ of below 0.2.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-10-21T20:47:55.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9228" PostTypeId="1" AcceptedAnswerId="9238" CreationDate="2014-10-20T02:13:08.053" Score="5" ViewCount="362" Body="&lt;p&gt;I am not talking the typical breakdown such as Pilot/Mechanical/Other, but rather, more specific things such as, engine failure, Stall/Spin on approach, controlled flight into terrain... etc&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2014-10-20T15:56:29.823" Title="Has anyone compiled all the NTSB accident reports and broke down the percentages for cause of accident and fatalities?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;ntsb&gt;" AnswerCount="1" CommentCount="12" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9229" PostTypeId="2" ParentId="9225" CreationDate="2014-10-20T05:03:27.623" Score="6" Body="&lt;p&gt;I know film projectors were definitely used on early 747s - converting part of the passenger area into a theater is part of the design. I was able to dig up the photo below showing the projector mechanism, which is pretty impressive to look at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KyZxJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KyZxJm.png&quot; alt=&quot;747 Film Projector (Screencap)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure whose system that is, but it looks like a 35mm projector so it probably predates the TRANSCOM cassettes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can't help you with #2 or #3 though.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1696" LastEditDate="2015-12-14T20:38:10.403" LastActivityDate="2015-12-14T20:38:10.403" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9230" PostTypeId="1" CreationDate="2014-10-20T05:38:36.873" Score="4" ViewCount="1033" Body="&lt;p&gt;What would be the approximate difference in weight for a Continental 100 hp engine compared to a 150 hp?&lt;/p&gt;&#xA;" OwnerUserId="3983" LastEditorUserId="1696" LastEditDate="2015-04-27T17:11:12.887" LastActivityDate="2015-04-27T17:11:12.887" Title="What is the weight difference between 100 hp and 150 hp Continental engine?" Tags="&lt;piston-engine&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9231" PostTypeId="2" ParentId="9223" CreationDate="2014-10-20T07:02:27.927" Score="11" Body="&lt;p&gt;I am neither builder nor airport manager and can't provide details, but as there is no answer yet, I'll try to summarize the main differences between the materials:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Concrete can support highest loads and lasts long. It is however most expensive to build and when it eventually gets damaged, it can't be patched and has to be rebuilt in large slabs. It also requires stable base, because it is rigid. It is built in slabs with spaces between them that are required due to account for thermal expansions and give somewhat bouncy ride.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Asphalt. There is a big variation between different kinds of asphalt concrete, but it is generally cheaper than concrete, but can't support as big loads and is susceptible to damage by frost. Asphalt is never completely rigid and slowly deforms under load. This allows using it on unstable base, but it means bumps form by prolonged use reducing the total lifetime. It also easily cracks and when water freezes in the cracks, potholes quickly form. They can however be relatively easily patched. It does not require any thermal expansion gaps and provides smooth ride.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Asphalt and concrete can be combined. A concrete with a layer of asphalt on top provides the strength of concrete and smooth ride of asphalt. The asphalt also protects the concrete base from freezing water while itself can be easily patched. This is lately common on roads (where concrete alone is really uncomfortable), not sure how much on runways.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Gravel is simple to build; all you need is some stone from nearby quarry and a steamroller. The main disadvantages are risk of foreign object damage by loose stones thrown up by the wheels and need of regular maintenance. So it is used mainly in remote cold places where concrete would be too expensive and asphalt would not last long in prevailing weather conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rolled earth with or without grass is even simpler then gravel, used for small airports where big loads are not needed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When runway is listed as grass, it means it is not even rolled. Usually enough for small airplanes and obviously cheapest.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Other surfaces usually as provided by local conditions (snow, salt etc.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For every particular airport, the investor evaluates the available technologies whether they can handle the expected traffic (to handle large jets like 747 or A380 concrete or concrete-asphalt combination is preferred), whether they are buildable in given location (the ground has to support the weight too) and how much building them will cost and choose the option that satisfies the requirements and they have money for.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2019-03-11T19:08:44.577" LastActivityDate="2019-03-11T19:08:44.577" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9232" PostTypeId="2" ParentId="9230" CreationDate="2014-10-20T07:35:48.077" Score="5" Body="&lt;p&gt;Which variants are you specifically talking about?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Continental O-200-A (100hp) weighs 170.18 lb (77.19 kg) dry, without accessories.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find a 150hp Continental, so here is the closest variant I could find:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Continental O-300 (145hp) weighs 268 lbs (121.5 kg) dry, without starter or generator&lt;/li&gt;&#xA;&lt;li&gt;The O-300 is also listed as a C-145 and as a C-175&lt;/li&gt;&#xA;&lt;li&gt;E165-2 165 hp dry weight 351 lb (159 kg) - Variant of the O-470&lt;/li&gt;&#xA;&lt;li&gt;E165-3 165 hp  dry weight 352 lb (160 kg) - Varian of the O-470&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I hope that's what you were looking for.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="3266" LastEditDate="2014-10-20T20:32:48.017" LastActivityDate="2014-10-20T20:32:48.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9233" PostTypeId="2" ParentId="9134" CreationDate="2014-10-20T07:47:00.853" Score="11" Body="&lt;p&gt;As someone already said, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=80a5b18b20a48d67997e6d51e202012c&amp;amp;node=32:6.1.1.6.10&amp;amp;rgn=div5#32:6.1.1.6.10.3.1.5.9&quot;&gt;32 CFR 855, Table 1&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Service members, operating their own aircraft, leased aircraft, or other available aircraft for official duty travel (temporary duty, permanent change of station, etc.) or for private, non revenue flights&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This of course means you still need to contact base ops for a Prior Permission Required (PPR) of some sort (if required).  If the base has an &lt;a href=&quot;https://www.usafservices.com/Managers/AeroClubs.aspx&quot;&gt;Aero club&lt;/a&gt;, then your logisitcal considerations are much less (most aircraft probably don't want to refuel on JP-8).  &lt;a href=&quot;http://usmilitary.about.com/od/aeroclubs/&quot;&gt;The list of Aero Clubs seems to have decreased since I was in though&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://navyflightmanuals.tpub.com/P-305/P-3050072.htm&quot;&gt;Flight Infomration Handbook&lt;/a&gt; will have all the base requirements listed in it.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="3266" LastEditDate="2014-10-20T11:54:58.923" LastActivityDate="2014-10-20T11:54:58.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9234" PostTypeId="1" AcceptedAnswerId="9235" CreationDate="2014-10-20T08:15:22.273" Score="19" ViewCount="1336" Body="&lt;p&gt;I have a small but quite busy GA (General Aviation) airport I operate out of that gets over 140,000 of operations per year.  It's a popular GA destination, has an active school, and the area schools use it as a great short, narrow, practice runway. The AFD (Airport/Facility Directory) entry for the airport lists the runway as having a Tri Color VASI (Visual Approach Slope Indicator) at each end.  It doesn't exist.  As far as I've gathered it &lt;em&gt;might&lt;/em&gt; have existed 20 years ago.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does an oversight like this exist for such an extended period of time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this something that should be reported?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instrument approach plate lists the VASI as well, but it's never been NOTAM'd out of service.  Does this create a hazard to potential IFR traffic?&lt;/p&gt;&#xA;" OwnerUserId="3516" LastEditorUserId="572" LastEditDate="2015-02-19T08:57:04.020" LastActivityDate="2015-02-19T08:57:04.020" Title="Why does the airport plate list a VASI that does not exist?" Tags="&lt;faa&gt;&lt;airport-lighting&gt;&lt;vasi&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9235" PostTypeId="2" ParentId="9234" CreationDate="2014-10-20T09:58:18.933" Score="27" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How does an oversight like this exist for such an extended period of time?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because it doesn't get reported. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this something that should be reported?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, it should be reported, otherwise this oversight will exist for an extended period of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot;&gt;dAFD website&lt;/a&gt; contains a link that should be followed to &lt;a href=&quot;https://nfdc.faa.gov/portal/airportChanges.do&quot;&gt;[r]eport any A/FD errors or changes&lt;/a&gt;. Somewhere down those links you'll find plethora of forms and rather confusing texts which seem not really helpful when you want to report a missing VASI. That brings us back to the answer on your first question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the comments, Kevin Cathcart pointed out the &lt;a href=&quot;https://nfdc.faa.gov/nfdcApps/actions/PublicAction?action=showNewAdiForm&quot;&gt;Aeronautical Data Inquiries form&lt;/a&gt; which is the appropriate form to flag the problem. Alternatively you can contact the NFDC (National Flight Data Center) via phone at 1-(866) 295-8236.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does this create a hazard to potential IFR traffic?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whether it is a potential hazard depends mainly on the presence of other source of vertical guidance. Is there an ILS / gideslope active? No vertical guidance at all is a safety risk in low visibility conditions.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-20T20:45:07.363" LastActivityDate="2014-10-20T20:45:07.363" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9236" PostTypeId="1" AcceptedAnswerId="9239" CreationDate="2014-10-20T13:16:31.447" Score="7" ViewCount="850" Body="&lt;p&gt;For displays in international airshow, Airbus uses A380 whose livery is the one of customers. Here are some examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=VdhEc07mB9Q&quot; rel=&quot;nofollow&quot;&gt;Le Bourget 2011&lt;/a&gt;: Korean Air&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=ZCTPqCS8iM0&quot; rel=&quot;nofollow&quot;&gt;Farnborough 2012&lt;/a&gt;: Malaysian Airline&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=YBpButcpbiQ&quot; rel=&quot;nofollow&quot;&gt;Le Bourget 2013&lt;/a&gt;: British Airways&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are those aircraft regular newly built aircraft ready to be delivered to airlines (with all the seats and passenger equipment inside)? Are those aircraft specially prepared?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1678" LastEditDate="2016-01-22T11:20:50.027" LastActivityDate="2016-01-22T11:20:50.027" Title="Are the aircraft used for the A380 display ready to be delivered to airlines?" Tags="&lt;airbus-a380&gt;&lt;airshow&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9237" PostTypeId="2" ParentId="9156" CreationDate="2014-10-20T15:28:23.537" Score="5" Body="&lt;p&gt;Adding this to other's answers, the First Officer (FO) is also a member of the crew. He or she, is therefore, also responsible for ensuring the safety of the aircraft to the best of his / her ability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FO has a control column and primary display identical to the Captain's. In a situation like this, it is essential for the FO to override the decision of the Captain. I can't say for all airlines, but I know certain airlines do practice the following scenarios in CRM trainings:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot incapacitation&lt;/li&gt;&#xA;&lt;li&gt;Pilot disorientation&lt;/li&gt;&#xA;&lt;li&gt;A senior crew member performing incorrectly which compromises the safety of the aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The GIST here is that the PF (pilot flying) may or may not recognize something is wrong. The PM (pilot monitoring) has to, using his experience as a superior pilot judgment,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Voice out his concerns&lt;/li&gt;&#xA;&lt;li&gt;Suggest corrective actions&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;take over control&lt;/em&gt; when deemed necessary&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-10-20T15:28:23.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9238" PostTypeId="2" ParentId="9228" CreationDate="2014-10-20T15:56:29.823" Score="5" Body="&lt;p&gt;There's a book called &quot;The Killing Zone - How and Why Pilots Die&quot; by Paul A. Craig which has a great deal of statistical work in it around aircraft accidents which may be useful to you. It's an alarming title which might make you think it's some sort of sky is falling mentality, but it's actually very sensible, statistics-based information about aviation accidents. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-20T15:56:29.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9239" PostTypeId="2" ParentId="9236" CreationDate="2014-10-20T16:03:47.877" Score="6" Body="&lt;p&gt;In all cases the answer is yes, those aircraft were all outfitted with seats, and at least very close to being ready for delivery to the customer. Installing interiors and seats is a regular part of the production process, and it's unlikely that the plane would be pulled from the line before seats are installed, and worked back in later. From looking at &lt;a href=&quot;http://www.abcdlist.nl/a380f/a380f.html&quot;&gt;rollout and delivery dates&lt;/a&gt;, these aircraft all had about 7 months between rollout and delivery, with the air show appearance happening within a month of delivery. Also, the aircraft are used as static displays while not flying, allowing people to walk through and see the interior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2011, the Korean Air A380 &lt;a href=&quot;http://multimedia.ctk.cz/?setOrder=asc&amp;amp;setSite=foto-set&amp;amp;setId=9011219&amp;amp;select-continue=1&quot;&gt;indeed had seats in it&lt;/a&gt;. It was delivered in the middle of July.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2012, the Malaysian A380 &lt;a href=&quot;http://airwingmedia.com/factory-fresh/2012/video-tours-first-malaysia-airlines-airbus-a380/&quot;&gt;also had seats installed&lt;/a&gt;. It was delivered at the end of July.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2013, the British Airways A380 probably had seats installed. I can't find any pictures of the inside, but it was delivered shortly after &lt;a href=&quot;http://www.businesstraveller.com/news/baa-s-a380-arrives-at-heathrow&quot;&gt;in early July&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus also tends to bring a flight test A380 like MSN001 (first to fly, registered F-WWOW) for display, and has a &lt;a href=&quot;http://www.youtube.com/watch?v=XBuBC8sNUR4&quot;&gt;more unusual interior&lt;/a&gt;. The Korean Air A380 was used for the display in 2011 after the flight test plane MSN004 had a &lt;a href=&quot;http://www.airlinereporter.com/2011/06/airbus-a380-wing-hits-building-at-paris-airshow/&quot;&gt;bit of a mishap&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-20T16:03:47.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9240" PostTypeId="2" ParentId="9236" CreationDate="2014-10-20T16:36:55.333" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Are those aircraft regular newly built aircraft ready to be delivered to airlines&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes. At least in the case of the aircraft in BA livery at the Paris airshow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:British_Airways_Airbus_A380-841_F-WWSK_PAS_2013_01.jpg&quot; rel=&quot;nofollow&quot;&gt;other photos&lt;/a&gt; taken at that event, it had registration F-WWSK and construction number 095&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BA registered it as &lt;a href=&quot;http://www.airfleets.net/ficheapp/plane-a380-95.htm&quot; rel=&quot;nofollow&quot;&gt;G-XLEA&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That was &lt;a href=&quot;http://www.flyertalk.com/forum/british-airways-executive-club/1476013-ba-fleet-new-aircraft-arrivals-retirements-master-tracker.html&quot; rel=&quot;nofollow&quot;&gt;listed as delivered 4 July&lt;/a&gt;  so almost certainly fully completed ready for BA when at the airshow on 17th June.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-10-20T16:36:55.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9242" PostTypeId="1" AcceptedAnswerId="9246" CreationDate="2014-10-20T20:55:20.100" Score="36" ViewCount="12134" Body="&lt;p&gt;When you have a look at the fleets from big airlines like United, Delta, Lufthansa, BA, AF, etc. it seems that they have almost every model Boeing and Airbus released in their fleet. And my question is, why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I assume is that such a big variety would increase the costs for maintenance, training, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, for example, why use the A330 as well as the 777? Why operate both the A320 and 737?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me as a passenger it is comfortable because I like to test and review different aircraft; but for these airlines' Operations divisions it must be horrible!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are probably reasons to do so otherwise they would not have this variety. What are these reasons?&lt;/p&gt;&#xA;" OwnerUserId="3988" LastEditorUserId="97" LastEditDate="2014-10-22T19:27:47.547" LastActivityDate="2014-12-30T22:03:05.217" Title="Why do some airlines operate fleets so diversified?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;" AnswerCount="8" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9243" PostTypeId="1" CreationDate="2014-10-20T20:58:29.910" Score="70" ViewCount="15803" Body="&lt;p&gt;Imagine that the pilots on a jet aircraft determine that it will crash. Consider what would happen if the design of the craft allowed it to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Break into four pieces&lt;/li&gt;&#xA;&lt;li&gt;Each piece is pressurized independently&lt;/li&gt;&#xA;&lt;li&gt;Each piece is attached to large parachutes, similar to how they bring down Soyuz or other space crafts returning to Earth&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Would that not work so that passenger jets are brought down safely instead of crashing?&lt;/p&gt;&#xA;" OwnerUserId="3989" LastEditorUserId="97" LastEditDate="2014-11-09T02:33:55.583" LastActivityDate="2016-07-05T16:43:45.887" Title="Why don't commercial jet aircraft have a break-apart, parachute escape system?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;jet&gt;&lt;airframe-parachute&gt;" AnswerCount="11" CommentCount="13" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9244" PostTypeId="2" ParentId="9242" CreationDate="2014-10-20T21:16:27.933" Score="10" Body="&lt;p&gt;Airlines usually try to avoid having more than one type for each size exactly because it makes maintenance more complicated and expensive. Low-cost carriers go even further and operate only one type altogether.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines that have diverse fleet usually have acquired them by merging with other companies that had different fleets. Note that all the companies you mention each swallowed several other airlines recently enough to still have those aircraft in active service.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-10-20T21:16:27.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9245" PostTypeId="2" ParentId="9243" CreationDate="2014-10-20T21:23:59.860" Score="92" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;wouldnt that work for keeping a majority of passenger jets from crashing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The majority of passenger jets don't crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designing an aircraft like that would incur very substantial weight penalties. The Space Shuttle booster rocket parachutes weight 990kg, each (it needs 3) plus 550 kg for the drogue chute needed to pull out the main canopies. Plus another to pull out the 550kg drogue. Where are you going to put that much nylon?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's regular maintenance of stuff that large and heavy - you will need an entire empty hangar to repack things along with a crew and a crane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also consider how you are going to break up a commercial airliner in an orderly manner. It would have to be designed for it and lined with explosives. That's going to be really popular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, parachutes need time to work. Large parachutes need considerable time. So this whole process only helps if there's a problem in cruise flight, and that's the phase with the lowest accident rate. Parachutes below 1000 feet are just excess weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Semi-related Addendum: After Challenger went boom the Space Shuttles were fitted with a crew escape system. It was intended to allow the crew to exit when the craft was under control but unable to reach a survivable landing site. Re-read that carefully: &lt;em&gt;when the craft was under control&lt;/em&gt;. The crew exits at reasonable altitudes and the Shuttle crashes under remote control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parachutes simply haven't been a viable option for commercial air transportation since the DC-3 era.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2014-10-21T14:03:07.133" LastActivityDate="2014-10-21T14:03:07.133" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9246" PostTypeId="2" ParentId="9242" CreationDate="2014-10-20T21:24:16.940" Score="37" Body="&lt;p&gt;There are two philosophies for fleet selection:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;One type / model or one manufacturer approach&lt;/li&gt;&#xA;&lt;li&gt;Multi manufacturer divide and conquer approach&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;First of all, a single model fleet is only possible for airlines that operate on sectors of comparable length. You can't do intercontinental and regional flights with the same aircraft model efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you observe, there are obviously costs associated with flying different types of aircraft. A single type fleet like for example Ryanair (B738), Southwest (B73*) and Easyjet (A320 family) operate, means the cost of maintenance, training, etc can be kept low. Adding a few aircraft of another type to the fleet would mean additional tools in stock, diversified training and a separate flight crew group and lots of other cost factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft manufacturers know that too. So if you need another 10 - 20 aircraft, your standard supplier will ask a high price for this fleet extension, knowing that the competition is never able to put in a compelling offer when all additional cost are taken into account. Only if the batch size is large enough the competitor might be able to offset the additional costs with a unit discount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is where the mixed fleet operator has an advantage. Since the additional overhead costs of a couple extra aircraft from type A or B are minimal, they &lt;a href=&quot;http://www.flightglobal.com/news/articles/routes-emirates-to-re-evaluate-a350-alongside-787-next-404005/&quot;&gt;have a better position&lt;/a&gt; while negotiating with the manufacturers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Single manufacturer airlines usually order aircraft in &lt;a href=&quot;http://corporate.ryanair.com/news/news/14908-ryanair-places-order-for-up-to-200-new-boeing-737-max-200-aircraft-worth-up-to-22bn/?market=en&quot;&gt;large numbers&lt;/a&gt;, otherwise they would not get a proper deal; multi type airlines can order aircraft in lower numbers. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;And then there are politics. Sometimes a national airline will be subjected to political pressure to buy from a certain manufacturer. This is especially the case for airlines operating in the international / intercontinental market. The extra fleet cost incurred will be (partially) offset by deals in another field.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-21T08:31:15.960" LastActivityDate="2014-10-21T08:31:15.960" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9247" PostTypeId="2" ParentId="9242" CreationDate="2014-10-20T21:45:17.017" Score="0" Body="&lt;p&gt;An airliner (a large one as you mentioned) tend to get airplanes of different manufacturers for several reasons. Some are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Destinations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airline's airplanes fly to destinations of varying distances and traffic loads from its hub. Operating different types of aircraft according to the needs of that particular route would drive the need of different types of airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Deals and Incentives&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane manufacturers may offer different deals to an airline at different times. Such business decisions are always made to a company's best interests.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Hiring and Training&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines tend to hire flight crew with different ratings so that will have a wider experience and proficiency.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-10-20T21:45:17.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9248" PostTypeId="2" ParentId="9242" CreationDate="2014-10-20T22:27:14.530" Score="10" Body="&lt;p&gt;Some amount of diversity is good for business.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From time to time, an airworthiness directive might force all planes of a particular model to be grounded.  This has happened for the 787, for example, due to concerns over battery safety.  Even with more established models, urgent safety issues may surface.  A high-profile example would be the &lt;a href=&quot;http://www.nytimes.com/2009/08/01/world/europe/01crash.html&quot;&gt;Airbus A330 and A340 pitot tubes&lt;/a&gt;, after the Air France Flight 447 accident.  Grounding the entire airline's fleet would be an unacceptable business risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having a fleet of planes from more than one manufacturer could result in better deals during purchase negotiations.&lt;/p&gt;&#xA;" OwnerUserId="487" LastActivityDate="2014-10-20T22:27:14.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9249" PostTypeId="1" AcceptedAnswerId="9250" CreationDate="2014-10-20T23:33:00.957" Score="30" ViewCount="5861" Body="&lt;p&gt;I remember reading a book about private piloting techniques, (I can't remember the title; it has been so long; perhaps I can check my library history or something to see later), and I saw something bizarre.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The author was discussing instruments, and what to do in case of failures. He wrote something about how, in the case of a failure of a critical instrument, in a situation where you really need it, that one should punch out (or otherwise destroy) the glass of the gauge, to allow air into the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any way something like this could be useful, or at least theoretically logical? Can anyone deduce any sense out of this?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="14957" LastEditDate="2016-08-27T05:59:31.087" LastActivityDate="2016-08-27T05:59:31.087" Title="Can instruments be fixed via a swift punch?" Tags="&lt;flight-instruments&gt;&lt;gauge&gt;&lt;failures&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9250" PostTypeId="2" ParentId="9249" CreationDate="2014-10-20T23:53:03.567" Score="35" Body="&lt;p&gt;If the static port gets blocked in an aircraft with no alternate static port, you can break the glass of the VSI (Vertical Speed Indicator) to allow air from inside the cockpit in the static system. By doing this you will sacrifice the VSI in favour of the altimeter and airspeed indicator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to venturi effects, air inside the cockpit has usually a slightly lower pressure than the pressure measured by the static port outside your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This causes your altimeter to indicate a higher altitude and the airspeed indicator will also indicate a greater speed. The VSI is useless after you break it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Needless to say this does not apply to pressurized cabins nor to glass cockpits...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This works because the inside of the VSI contains a diaphragm in a pressure chamber. The diaphragm is connected to the static system through an unrestricted tube. The chamber is connected to the static system through a  restricted (calibrated) leak. If the static pressure changes, the pressure in the diaphragm  changes instantly, while the chamber pressure lags slightly behind. This causes the membrane to expand / retract which drives the needle on the instrument. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the glass is broken, the chamber will be at the same pressure as the cockpit. Through the calibrated leak, the static system will be levelled with the cockpit pressure, but of course with a delay as well. The VSI will now work in opposite direction (if you didn't destroy the needle). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v4QiP.jpg&quot; alt=&quot;IVSI&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The inner workings of an IVSI&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some VSI apparently have the calibrated leak into the cockpit already. For such VSI's smashing the glass does not work. Here the diaphragm should be destroyed as well. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-10-21T08:57:59.427" LastActivityDate="2014-10-21T08:57:59.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9251" PostTypeId="2" ParentId="9249" CreationDate="2014-10-20T23:57:17.393" Score="8" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/faa-h-8083-15b.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Instrument Pilot Handbook&lt;/a&gt; (11-8) mentions this as an alternate source if you lose your static source (not vacuum).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, I don't think every VSI is identical.  I have seen arguments that some are not vented the same way and may not provide a valid static source. &lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="97" LastEditDate="2014-10-22T19:37:03.280" LastActivityDate="2014-10-22T19:37:03.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9252" PostTypeId="1" AcceptedAnswerId="9280" CreationDate="2014-10-21T00:56:37.463" Score="5" ViewCount="494" Body="&lt;p&gt;As shown in &lt;a href=&quot;http://www.youtube.com/watch?v=KluDuc93QMU&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt;, what causes a weight-controlled &lt;a href=&quot;http://en.wikipedia.org/wiki/Ultralight_aviation&quot; rel=&quot;nofollow&quot;&gt;microlight&lt;/a&gt; to tumble, and is it possible to stop it from tumbling once it starts?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="1696" LastEditDate="2015-04-27T16:16:35.613" LastActivityDate="2015-04-27T16:16:35.613" Title="What makes a weight-controlled microlight tumble, and can it recover?" Tags="&lt;safety&gt;&lt;ultralight&gt;&lt;stability&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9253" PostTypeId="1" AcceptedAnswerId="9259" CreationDate="2014-10-21T01:58:07.780" Score="13" ViewCount="4099" Body="&lt;p&gt;Could I, as a passenger, get a picture with the pilots in the cockpit before takeoff/after landing? I'm asking specifically about any rules that would deny a passenger into the cockpit. I know this is too broad and subject to change from airline to airline, but generally would I be allowed? What about domestic vs international flights?&lt;/p&gt;&#xA;" OwnerUserId="2353" LastEditorUserId="97" LastEditDate="2014-10-22T19:38:11.547" LastActivityDate="2021-02-18T02:41:22.563" Title="Can I get a photo with the pilots?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;passenger&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9254" PostTypeId="1" AcceptedAnswerId="9266" CreationDate="2014-10-21T04:49:03.803" Score="16" ViewCount="1703" Body="&lt;p&gt;I've always dreamed of buying my own plane. Turns out, they can be had for $20,000 on eBay.  This sounds too good to be true. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What checklist of items are essential to prevent my new purchase from falling out of the sky?&lt;/p&gt;&#xA;" OwnerUserId="3994" LastEditorUserId="69" LastEditDate="2015-04-25T03:57:50.367" LastActivityDate="2015-04-25T03:57:50.367" Title="What are the must-checks for purchasing an airplane?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-purchase&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9255" PostTypeId="2" ParentId="9254" CreationDate="2014-10-21T06:25:08.143" Score="6" Body="&lt;p&gt;Well, this is a much more opinion based answer, but I'll give it a go:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/aw_overview/&quot; rel=&quot;noreferrer&quot;&gt;Airworthiness Certificate&lt;/a&gt; (FAA link)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22587&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Maintenance logs&lt;/a&gt; (FAA link) (&lt;a href=&quot;http://flighttraining.aopa.org/magazine/1998/November/199811_FT_Owner_Engine_Overhauls.html&quot; rel=&quot;noreferrer&quot;&gt;in particular engine overhaul&lt;/a&gt; - AOPA link)&lt;/li&gt;&#xA;&lt;li&gt;Much like a CarFax, check if it has been involved in &lt;a href=&quot;http://www.ntsb.gov/aviationquery/&quot; rel=&quot;noreferrer&quot;&gt;any accidents&lt;/a&gt; (NTSB link, you can do a registration querry there)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;After that, I would say getting an independent inspection by a General Aviation mechanic, and go for a test flight with the current owner (hopefully they will be willing to fly in the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope that helps.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastActivityDate="2014-10-21T06:25:08.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9256" PostTypeId="2" ParentId="9253" CreationDate="2014-10-21T06:35:22.887" Score="10" Body="&lt;p&gt;If you were going to try to do something like that, &lt;em&gt;it would depend greatly on the crew&lt;/em&gt;.  You may be limited to getting the picture taken in the doorway to the cockpit, and for the sake of security, I would suggest after landing (generally when the pilots are doing their, &quot;Bye, thanks for flying&quot; thing as people deplane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would probably have to coordiante with the flightcrew, and make sure you are not impeeding progress of other passengers. Furthermore, if you do it, others may want to do the same, so again, that may factor into the decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are going to try, I would suggest doing it on an airline that has a reputation for being more &quot;fun&quot; (like Southwest).  Also, many airlines have a sort of &quot;public affairs&quot; line that you can call and try to pre-coordiante such activity.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="97" LastEditDate="2014-10-22T19:40:21.157" LastActivityDate="2014-10-22T19:40:21.157" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9257" PostTypeId="2" ParentId="9242" CreationDate="2014-10-21T06:38:07.480" Score="2" Body="&lt;p&gt;Consider sometimes that an airline doesn't own these aircraft - they may be leasing them for a short term.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft leasing comes in two flavors - ACMI &quot;wet lease&quot; where all the airline is doing is slapping their logo on the aircraft, everything else Aircraft, Crew, Maintenance Insurance is included; and then a &quot;dry lease&quot; where only the aircraft is leased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is normally done during busy periods (for example during the annual &lt;a href=&quot;http://en.wikipedia.org/wiki/Hajj&quot; rel=&quot;nofollow&quot;&gt;Hajj season&lt;/a&gt;) many airlines will operate a type different than their normal operations.  The 747 is a favorite for leasing during this period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So although you may be seeing the aircraft being flown by your favorite airline, the leasing cost may offset the profit for that particular route.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-10-21T06:38:07.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9258" PostTypeId="2" ParentId="9253" CreationDate="2014-10-21T07:05:05.637" Score="9" Body="&lt;p&gt;As you have said, cockpit entry rules vary depending on the country and even airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US visitors are fobidden from being in the cockpit when the aircraft is in flight, but to my knowledge it is still &lt;em&gt;legally&lt;/em&gt; permissible when parked at the gate. Airlines may have their own rules surrounding entry though. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't tried in the US, but elsewhere I find that heading to the cockpit as really depends on the crew members and workload. Before or after a short flight with a quick turnaround the pilots may rightly say they are too busy. After a long international flight they may just want to get to their hotel! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suggest that in cruise, when the FAs don't look too busy, just politely ask one of them if it would be possible to visit after the flight - explain that you're an enthusiast, etc. It'll help if you've got a kid with you! Hopefully the FA will ask the flight crew and you'll get a positive answer. If you're really lucky (and in the right part of the world) you might even get an in-flight invite!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that pilots are real people. Most of them quite enjoy showing off their office to excited people when their circumstances permit. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-21T07:05:05.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9259" PostTypeId="2" ParentId="9253" CreationDate="2014-10-21T08:14:33.453" Score="20" Body="&lt;p&gt;I don't know about the situation specifically in the US, but in my - mostly European - experience crew are happy to welcome you to their office after flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I feel the need to see the cockpit or discuss things with the pilots I try to ask the flightcrew before take-off if I can meet them after the flight. Sometimes I explain my interests to the cabin crew and often they will arrange the visit. In a few cases I just asked while deboarding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the aircraft type and airport situation you have to think about the logistics a bit. In single aisle aircraft, if you start a discussion with crew while deboarding, you are blocking the queue. This gives the feeling that it is an inconvenient moment and reduces your chances. So if you ask at the last possible moment, make sure most people already exited before you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if passengers are transported to the terminal by bus, you will be holding the bus since you are the last to get off. This reduces the time you can spend in cockpit drastically. If you expect to be bussed to the terminal, ask cabin crew before the descent and don't wait until everybody has exited.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-11-02T13:17:45.093" LastActivityDate="2016-11-02T13:17:45.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9260" PostTypeId="2" ParentId="9243" CreationDate="2014-10-21T09:42:13.853" Score="29" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/9245/946&quot;&gt;Paul's answer&lt;/a&gt; covers the main points (difficulty, expense, weight); I want to flesh out the rarity of use aspect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Paul says, most accidents happen during take-off and landing, when the system is useless because the parachutes wouldn't have enough altitude to deploy. The only time you'd be able to use this system would be if you were flying at a decent altitude and you knew in advance that the plane was going to crash. This almost never happens. Perhaps parachuting to earth would be a better option than trying to ditch a plane on water, especially over the ocean, but ditchings are very rare. Otherwise, unless there's been some mechanical failure that makes the plane uncontrollable, an emergency landing is probably going to be a better bet, even if all your engines are out and you have to glide &amp;ndash; and a large passenger plane can glide for 20&amp;ndash;25 minutes from altitude. In most circumstances, an intact plane can fly a decent distance and it would be very, very dangerous to turn any kind of flyable plane into a collection of free-falling components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indeed, the proposed system would be useful in such a tiny fraction of air accidents that you'd probably find it causing more deaths than it prevented. You're talking about fitting tens of thousands of planes with probably hundreds of explosive charges each. How many maintenance workers are going to be killed by how many accidental detonations? How many times is it going to fire accidentally in mid-air due to, say, a small cabin fire in just the wrong place or a lightning strike?&lt;/p&gt;&#xA;&#xA;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-10-26T11:57:37.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9261" PostTypeId="2" ParentId="9242" CreationDate="2014-10-21T10:00:17.203" Score="2" Body="&lt;p&gt;And then there's airlines that have fleets of aircraft inherited from other airlines they took over/merged with.&lt;br/&gt;&#xA;And there's the airlines in the process of replacing their fleet with something new.&lt;br/&gt;&#xA;Airlines that are expanding and decide to buy new aircraft of a more modern type and keep the old ones for now because it makes no economic sense to scrap or sell them.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;The reasons are plenty, even if the airline could in theory use one single type for its entire route network and use it efficiently (which use pattern would seriously limit the scope of an airline's operations, you'd not be able to have for example flights within Europe and flights from Europe to the USA and Japan).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-10-21T10:00:17.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9262" PostTypeId="2" ParentId="9242" CreationDate="2014-10-21T10:04:56.383" Score="16" Body="&lt;p&gt;One reason that I have not seen addressed in any of the extant terrific answers is &lt;strong&gt;acquisitions&lt;/strong&gt;. Many times over the past few decades airlines have been sold, merged, or folded. Each time, the airlines' aircraft go to new owners who &lt;em&gt;may or may not&lt;/em&gt; already operate acquired aircraft models at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As the airlines' owners change, there is churn in which airlines operate which equipment.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="354" LastActivityDate="2014-10-21T10:04:56.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9263" PostTypeId="1" AcceptedAnswerId="9265" CreationDate="2014-10-21T12:13:58.610" Score="6" ViewCount="1631" Body="&lt;p&gt;Inspired by &lt;a href=&quot;https://aviation.stackexchange.com/q/9249/65&quot;&gt;this question&lt;/a&gt; about breaking the glass of instruments, I was wondering if a sufficient level of vacuum can be achieved by using a vacuum cleaner on the inlet, or simply sucking through a straw connected to the vacuum inlet, in case the artificial horizon's vacuum pump failed?&lt;/p&gt;&#xA;" OwnerUserId="3493" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2018-12-28T07:55:58.690" Title="Can a vacuum cleaner create sufficient vacuum to operate the artificial horizon?" Tags="&lt;emergency&gt;&lt;flight-instruments&gt;&lt;failures&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9264" PostTypeId="2" ParentId="9243" CreationDate="2014-10-21T13:02:38.503" Score="14" Body="&lt;p&gt;I want to comment on the 'break apart into 4 sections' comment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your 4 parts were two wings, tail and the pressurized portion, thus reducing the weight that needed to be lowered safely (and removing some of the problems that Paul pointed out), you still have one major problem:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You've just designed a plane that has a way to specifically remove its wings in flight.  This would be a terrorists's dream ... no need to bring their own explosives if they can hack into the control systems (don't even need to disable the parachute deployment, if you can get it to trigger when the plane's low enough, like while it's coming in for a landing ... or on takeoff, so it throws lots of fuel at the same time)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but I will mention that there &lt;em&gt;do&lt;/em&gt; exist &lt;a href=&quot;http://sportair.aero/6-chutes/whole-plane-parachutes/&quot;&gt;whole-plane parachutes&lt;/a&gt;, but they're for much, much smaller planes.  (and they claim they only need 270' as they're rocket-deployed, so no drogue chute needed)&lt;/p&gt;&#xA;" OwnerUserId="3999" LastActivityDate="2014-10-21T13:02:38.503" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9265" PostTypeId="2" ParentId="9263" CreationDate="2014-10-21T15:16:42.513" Score="9" Body="&lt;p&gt;The answer is a qualified yes: It's theoretically possible, but wholly impractical to provide a pressure source to your gyros from within the cockpit, at least the way you're describing.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Air-Driven gyros require a relatively constant pressure differential somewhere between 4 and 6 inches of mercury to operate correctly (this can be &quot;suction&quot; or &quot;pressure&quot;, but as vacuum/suction systems are more common let's stick with that term). We can split the difference and say we want to supply 5 inches of vacuum (which is usually right in the middle of the &quot;green arc&quot; for most vacuum gauges) - this is sufficient suction to keep the rotor spinning at an appropriate RPM so the instruments function as expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because a constant vacuum is required we can kill off one of the options: You won't be able to suck air through a straw to do this -- you would be constantly over-speeding or under-speeding the gyro rotor as you produce either too much vacuum (inhaling) or not enough (when you have to let go of the straw to exhale).&lt;br&gt;&#xA;The variable pressure would vary the rotor speed, and your instruments would be totally unreliable within a few breaths, defeating the purpose of the exercise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A household vacuum can provide the necessary pressure differential (&lt;a href=&quot;http://www.vacuumwizard.com/vacuum-cleaners-reviews.html&quot; rel=&quot;noreferrer&quot;&gt;these fine vacuum-rating folks&lt;/a&gt; tell me that &quot;An average vacuum will have a [suction] rating of around 80 inches of water&quot;, which Google tells me is around 5.9 inches of mercury. If you could hook the vacuum up to the aircraft's system downstream of the vacuum regulator (where the main vacuum pump hooks up) you could theoretically power your gyros normally.&lt;br&gt;&#xA;There are some caveats to using a vacuum cleaner idea besides the obvious &quot;How are you going to hook the vacuum up to the system?&quot; question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The vacuum cleaner specifications are presumably at or near sea level - they might not be able to provide adequate suction at higher altitudes. &lt;/li&gt;&#xA;&lt;li&gt;Powering the vacuum cleaner in this scenario is left as an exercise for the reader (most aircraft with air-driven gyros don't have household AC power in the cockpit - you could install an inverter, but vacuums pull quite a lot of power, so you'd need a high-amperage circuit to supply it. The draw from the vacuum may exceed the capacity of the plane's electrical system, and to remedy that we're getting into complicated major alterations...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are other more practical alternatives to an engine-driven vacuum pump to consider if you're worried about the reliability of your vacuum source:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.thevacsource.com/svs.php&quot; rel=&quot;noreferrer&quot;&gt;Precise Flight&lt;/a&gt; makes a standby vacuum system that ties into the engine intake.&lt;br&gt;&#xA;For normally-aspirated engines this works well as long as the engine is operating at part throttle: The manifold pressure differential is sufficient that it can supply suction for your gyros.  The downside is that you can't guarantee a stable vacuum source: at full throttle there will probably not be sufficient suction to operate the gyros (particularly at altitude).&lt;/li&gt;&#xA;&lt;li&gt;Pneumatic venturi tubes can be used to supply vacuum for aircraft in flight.&lt;br&gt;&#xA;These are bolted on to the airframe and use the slipstream air moving through a venturi to create the necessary vacuum. In extremely slow flight these may also fail to provide adequate vacuum. &lt;img src=&quot;https://i.stack.imgur.com/ahGUL.jpg&quot; alt=&quot;Venturi tube&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;Electric standby vacuum pumps are a popular option as they offer you the ability to keep using your main vacuum instruments regardless of throttle position or airspeed. The primary drawbacks are weight, space (for the installation), and power to run the motor.&lt;/li&gt;&#xA;&lt;li&gt;Electric gyro instruments are a popular option (though somewhat expensive): They provide a backup for the air-driven system using an independent power source.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-10-21T15:16:42.513" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9266" PostTypeId="2" ParentId="9254" CreationDate="2014-10-21T16:21:04.223" Score="21" Body="&lt;p&gt;There are plenty of great $20,000 aircraft out there - the hard part is &lt;em&gt;finding them&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;What to look for&quot; is an incredibly broad question, and varies substantially between different types of aircraft: You would not look for the same things on a Piper Comanche as you would on a Cessna 182.&lt;br&gt;&#xA;Accordingly the first thing you want to do is find a mechanic who is an expert in the particular type of aircraft to help you check it out and do a &quot;pre-purchase inspection&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finding those mechanics is actually pretty easy: Look for a &quot;type club&quot; that supports the aircraft you're considering and ask them for recommendations (e.g. for a Cessna &lt;a href=&quot;http://www.cessna.org&quot; rel=&quot;nofollow noreferrer&quot;&gt;I'd talk to the Cessna Pilot's Association&lt;/a&gt;, for a Cirrus &lt;a href=&quot;https://www.cirruspilots.org&quot; rel=&quot;nofollow noreferrer&quot;&gt;COPA&lt;/a&gt;, for most Piper aircraft &lt;a href=&quot;http://www.piperforum.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Piper forum&lt;/a&gt;, for Beechcraft &lt;a href=&quot;http://www.beechtalk.com/forums/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beech Talk&lt;/a&gt;, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Talk to folks on those forums (and to your mechanic) about what you, as a buyer, should be looking at before you get the mechanic involved for the more detailed inspection. There are lots of things you as a pilot (even a student pilot) can determine just by looking at a plane (and/or the logbooks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some key items to look at before you go see the plane:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;NTSB Records&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/9255/64&quot;&gt;Like Larian mentioned&lt;/a&gt; go to the NTSB site (or the equivalent if you're not in the USA) and search for accident records. Not every accident will show up in the database, but sometimes you'll find out that the cream puff aircraft being advertised has actually been &quot;substantially damaged&quot; in an accident. The NTSB database search is free and there's no reason not to do it.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Logbooks&lt;/strong&gt;&lt;br&gt;&#xA;All aircraft have logs, so if possible get a copy of them before you even go to look at the plane.&lt;br&gt;&#xA;Read through the logs (yes, all of them): You'll find all sorts of interesting things in there, but what you're mainly looking for is good, consistent maintenance and regular use of the aircraft. As a secondary concern you're looking for major repairs (or significant minor ones) that you might want to ask your mechanic about.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;FAA Records&lt;/strong&gt;&lt;br&gt;&#xA;You can &lt;a href=&quot;http://aircraft.faa.gov/e.gov/ND/&quot; rel=&quot;nofollow noreferrer&quot;&gt;request a copy of the FAA's records for an aircraft&lt;/a&gt; online for a small fee.  This includes registration information and any records of major repairs/alterations (&quot;Form 337&quot;) filed for the aircraft.  It is generally an &quot;interesting subset&quot; of the logs.&lt;br&gt;&#xA;This is something you'll want to have handy when your mechanic looks at the plane, though it's not something you need to have before you go look at it yourself. Theoretically the owner should have all the documents that this record contains as part of their records/logbooks, but in practice paperwork sometimes gets &quot;lost&quot;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If all that looks good it's time to look at the plane:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;How is the overall condition of the aircraft?&lt;/strong&gt;&lt;br&gt;&#xA;Cosmetics can lie, so don't be dazzled by a shiny coat of paint and a nice interior:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the on-board paperwork (ARROW) all in order?&lt;/li&gt;&#xA;&lt;li&gt;Are the tires, hoses, and other rubber components in good condition?&lt;/li&gt;&#xA;&lt;li&gt;Is the engine bay (relatively) clean? Are there any leaks, drips, or other items of concern?&lt;/li&gt;&#xA;&lt;li&gt;Are there obvious signs of damage (skin patches, dents, fabric tears, etc.)?&lt;/li&gt;&#xA;&lt;li&gt;Are there obvious signs of corrosion (bubbles under the paint, etc.)?&lt;/li&gt;&#xA;&lt;li&gt;Is the paint in overall good condition (no major chips, no cracks, no flaking)?&lt;/li&gt;&#xA;&lt;li&gt;Is the aircraft itself clean?&lt;br&gt;&#xA;(As much as cosmetics lie, a plane that looks like it's been neglected probably has been...)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Does the aircraft pass a &lt;em&gt;very thorough&lt;/em&gt; preflight?&lt;/strong&gt;&lt;br&gt;&#xA;Go through the preflight checklist with an eye for anything abnormal -- ask yourself &quot;Would I fly this aircraft today?&quot;.&#xA;If the answer is no, think carefully about why.&lt;br&gt;&#xA;If the answer is yes it may be time to test-fly with the current owner.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Does the aircraft operate correctly on the test flight?&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do the engine and propeller operate properly?&lt;/li&gt;&#xA;&lt;li&gt;Do all the instruments and avionics function correctly?&lt;/li&gt;&#xA;&lt;li&gt;Does the aircraft fly well? Can you trim for hands-off straight and level flight?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the aircraft passes all your checks it's time to turn your mechanic loose on it - they will inspect the aircraft for problems (major and minor) that you as a pilot might not notice which can wind up costing you a lot of money. This pre-purchase inspection (and the ensuing negotiation based on what the mechanic finds) is usually the last stop before handing over your money and taking the keys.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-10-21T16:21:04.223" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9267" PostTypeId="2" ParentId="9194" CreationDate="2014-10-21T17:27:45.697" Score="14" Body="&lt;p&gt;As DeltaLima said, the change in brightness is probably due to the difference in lighting. The first picture is above the clouds, so the air is clear and the light is primarily from the sun. The second picture is in the clouds, so the air is moist and the light is much more diffuse, coming from all directions. This diffuse lighting and the moisture on the wing surface help to reflect more light. You can see this in the already reflective leading edge as well. In the first picture, mostly the darker sky is reflected, but in the second picture, the brighter clouds are reflected. The reflected light will be more evident in the darker areas than lighter ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the materials, they represent different parts of the wing. The darker section represents the main structure of the wing, so the surface is made of metal for strength. The sections around it do not carry as much load so they are made of composites to save weight. The metal conducts heat better, so it will tend to condense more moisture than the composite section, as the aircraft is descending from cold, dry air into warmer, moist air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The surfaces do seem to have different finishes. This is probably related to the different types of material there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those pictures illustrate your question very well. I don't specifically remember noticing this sort of thing myself, but I will see if I have any myself showing the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also... anyone know what plane this is? The pointed ends of the shock bodies, the VG's, and the static wicks outboard of the aileron make me think a 737 classic with winglet retrofit.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-21T17:27:45.697" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9268" PostTypeId="1" AcceptedAnswerId="9272" CreationDate="2014-10-21T19:08:37.437" Score="4" ViewCount="1548" Body="&lt;p&gt;I've read many accident reports, and seen reconstructions, where instrument failures, disagreeing sensor sources and auto pilot faults have led pilots into believing that they are over speeding when they are not (think AF447), are descending when they are actually climbing etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that in all cases where this has led to a stall, the stick shaker has activated but the PF does not take the correct immediate action for stalls, instead continuing to believe the erroneous information they are being fed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the psychology of why this might be but is does strike me that many lives would have been saved if power up nose down had been applied.  I've not found a case yet where the shaker was wrong. This leads me to wonder...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How reliable are stick shakers?  Should they always be trusted?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some older types even had an automatic stick pusher but this does not seem to be present in modern designs.  Is this a consequence of shakers not being infallible?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="22726" LastEditDate="2019-04-20T03:46:55.487" LastActivityDate="2019-04-20T03:46:55.487" Title="How reliable are stick shakers?" Tags="&lt;aircraft-design&gt;&lt;flight-instruments&gt;&lt;accidents&gt;&lt;stick-shaker&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9269" PostTypeId="1" AcceptedAnswerId="9271" CreationDate="2014-10-21T21:47:46.310" Score="16" ViewCount="2575" Body="&lt;p&gt;I've often seen announcements by aircraft manufacturers or operators along these lines &quot;&lt;em&gt;Qantas announced today that they will buy 10 A380's and have taken options on another 10&lt;/em&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does it mean to &quot;have an option&quot;? I mean what level of contractual obligation exists between the manufacturer and the operator? Has a non-refundable deposit been paid - if so what sort of proportion of the eventual cost? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does &quot;having an option&quot; mean much more than the manufacturer hopes you'll order those planes and has pencilled you in on the manufacturing schedule?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also came across this on &lt;a href=&quot;http://www.virgin-atlantic.com/en/gb/allaboutus/pressoffice/faq/aircraftorders.jsp&quot;&gt;Virgin Atlantic's&lt;/a&gt; website:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Virgin Atlantic announced in March last year that it was ordering 15&#xA;  of the 787-9 Dreamliners - with options on ordering another eight&#xA;  787-9s and purchase rights on a further 20 aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've never heard of &quot;purchase rights&quot; so I'd be interested to know about the significance of &quot;purchase rights&quot; as well.&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="19" LastEditDate="2017-01-09T10:58:38.117" LastActivityDate="2017-01-09T10:58:38.117" Title="When buying airliners what is the difference between &quot;orders&quot;, &quot;options&quot; and &quot;purchase rights&quot;?" Tags="&lt;airline-operations&gt;&lt;terminology&gt;&lt;aircraft-purchase&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9270" PostTypeId="1" AcceptedAnswerId="9304" CreationDate="2014-10-21T21:48:39.570" Score="3" ViewCount="1211" Body="&lt;p&gt;Regarding the software that displays on a video the map with flight information for passengers, I would like to know:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The software from various airline companies seems to be more or less of a standard. So they should work in a similar fashion. Which input is needed in order to make it work (i.e., altitude, lat/lon coordinates, temperature)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Is it possible to acquire one version of this software and run it offline as a simulation, giving as input the needed information?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Is there a freeware solution to this? I'm more interested on information like the geography, cities, countries and borders.&lt;/p&gt;&#xA;" OwnerUserId="4006" LastEditorUserId="572" LastEditDate="2015-02-24T10:55:52.027" LastActivityDate="2015-02-24T10:55:52.027" Title="Is there an offline airplane route software similar to the in-flight entertaiment map?" Tags="&lt;software&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9271" PostTypeId="2" ParentId="9269" CreationDate="2014-10-21T22:36:35.130" Score="16" Body="&lt;p&gt;Manufacturers typically plan their aircraft production well into the future, which includes having a buyer lined up for each aircraft, so they will know their position in the production line and have an anticipated date for delivery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;strong&gt;order&lt;/strong&gt; means that the buyer has agreed to purchase a certain aircraft in the production line, at a certain price. The buyer may cancel, but there will probably be a substantial penalty for doing so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Option_%28aircraft_purchasing%29&quot;&gt;option&lt;/a&gt;&lt;/strong&gt; &lt;a href=&quot;http://airinsight.com/2013/07/16/what-is-really-an-order/#.VEbdhGOHlqk&quot;&gt;means&lt;/a&gt; that the manufacturer has reserved a certain aircraft in the production line for the buyer, usually at a certain price. However, the buyer will make the decision on whether to convert this to an &quot;order&quot; at a later date. There is less commitment than with an &quot;order&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/282396/&quot;&gt;purchase option&lt;/a&gt;&lt;/strong&gt; is even less of a commitment than an &quot;option.&quot; This just means that the buyer has agreed to purchase aircraft at a certain price, but it's not tied to a specific aircraft at that time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is becoming more common for buyers to mix these three types of orders, which allows them to have a balance of locking in an aircraft and price with orders, and less risk and commitment with options and purchase options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These can all be canceled, though of course there will be more penalties for breaking a more firm commitment. Buyers may also &lt;a href=&quot;http://www.reuters.com/article/2014/08/28/us-qantas-results-fleet-idUSKBN0GS04X20140828&quot;&gt;change their order&lt;/a&gt;, either for their own or the manufacturer's business reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The detailed finances of how much is actually paid for aircraft, and how much it costs to make or break any of these contracts, is generally not disclosed. Negotiations can be very specific to each order. For a rough estimate, &lt;a href=&quot;http://books.google.com/books?id=PWtzBAAAQBAJ&amp;amp;lpg=PA173&amp;amp;ots=Xy7TuKKU_H&amp;amp;pg=PA170#v=onepage&amp;amp;q&amp;amp;f=false&quot;&gt;this book&lt;/a&gt; considers that for 6 aircraft worth 45 million per unit, options would be worth 2.3 million each to the airline, or about 5%. &lt;a href=&quot;http://books.google.com/books?id=C8s3WY-zCBMC&amp;amp;pg=PA137&quot;&gt;This book&lt;/a&gt; estimates the down payment on a firm order at 10 to 15 percent, but notes that at least in the case of business and commuter aircraft, depending on market conditions, this may not always be required.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-22T15:18:04.180" LastActivityDate="2014-10-22T15:18:04.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9272" PostTypeId="2" ParentId="9268" CreationDate="2014-10-22T07:47:35.703" Score="7" Body="&lt;p&gt;The Australian Transport Safety Bureau recently published a comprehensive research paper on reported stall warnings in high capacity aircraft - &lt;a href=&quot;http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx&quot;&gt;http://www.atsb.gov.au/publications/2012/ar-2012-172.aspx&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report says that 30% of all stall warnings were false. Note that stall warnings aren't limited to the stick shaker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report says that of all reported stick shaker events, 16% were false warnings. Have a read of it, you'll find lots of interesting bits of information.  &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-10-22T07:47:35.703" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9273" PostTypeId="2" ParentId="9268" CreationDate="2014-10-22T08:29:05.890" Score="3" Body="&lt;p&gt;I'm going to lump stick shakers with all stall warning devices as they all have the same purpose. Stall warning devices are extremely reliable, and often more reliable than many pilots' judgement. When they go off it is because the conditions for a stall exist, and action should be taken. Occasionally a stall warning will go off momentarily in level flight because of turbulence, that usually is so short no action could be taken before the warning goes away.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Humans often have trouble in re-evaluating situations and can become fixated on one theory of events, especially under stress. People like to have confidence in their beliefs and judgement which leads to &lt;strong&gt;confirmation bias&lt;/strong&gt;, where people &quot;cherry pick&quot; details which fit their model of events. This can lead people to ignore information that is literally in their face, as in AF447, Northwest 6231, and other similar accidents. The airplane can be shouting &quot;STALL! STALL!&quot;, with an air horn blaring, stick shaker vibrating the pilot's hands until numb and the pilot will still be wondering why there's a high rate of descent. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So always trust your stall warning. Personally (I'm a light aircraft, not a commercial pilot) I practice stall recovery often where I immediately recover on the buzzer/horn, I do this so that it will become an instinctive reaction which I will do even if I'm overloaded and confused. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-22T08:29:05.890" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9274" PostTypeId="1" AcceptedAnswerId="9275" CreationDate="2014-10-22T08:43:38.180" Score="11" ViewCount="6055" Body="&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Taxiing&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; the definition of taxiing is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the movement of the aircraft on the ground &lt;strong&gt;under its own power&lt;/strong&gt; [however]&#xA;  push-back is &lt;strong&gt;not&lt;/strong&gt; considered taxiing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In contrast, &lt;a href=&quot;http://www.eurocontrol.int/lexicon/lexicon/en/index.php/Actual_Taxi-Out_Time&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol&lt;/a&gt; seems to define it as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;any movement on the ground&lt;/strong&gt; including push-back&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Any other reliable sources to look up for the correct definition?&lt;/p&gt;&#xA;" OwnerUserId="3708" LastEditorUserId="946" LastEditDate="2014-10-23T15:18:53.750" LastActivityDate="2017-03-31T14:27:07.210" Title="What is the definition of taxiing?" Tags="&lt;taxiing&gt;&lt;ground-operations&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9275" PostTypeId="2" ParentId="9274" CreationDate="2014-10-22T09:01:09.983" Score="13" Body="&lt;p&gt;Definitions always depend on their context, that is why documents often included a list of definitions. It allows authors to define terms in the context of the document. A definition context is not always a document, it could for example be a field of expertise as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Commercial Aviation Safety Team / International Civil Aviation Organization (CAST/ICAO) &lt;a href=&quot;http://www.intlaviationstandards.org/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Common Taxonomy Team&lt;/a&gt; (CICTT) &lt;a href=&quot;http://www.intlaviationstandards.org/Glossary.html#P-T&quot; rel=&quot;nofollow noreferrer&quot;&gt;taxi is defined&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft is moving on the aerodrome surface under its own power&#xA;  prior to takeoff or  after landing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More detail can be found in the &lt;a href=&quot;http://www.intlaviationstandards.org/Documents/PhaseofFlightDefinitions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;phase of flight&lt;/a&gt; definition document. &#xA;This is definition can be applied in many situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Eurocontrol definition you link to comes from the Air Traffic Flow &amp;amp; Capacity  Management (ATFCM) and Airport Collaborative Decision Making (A-CDM) domains where statistics about gate-to-runway time play an important role for planning purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that context it is not really interesting to distinguish the time that was spend in pushback from the time spend actually taxiing to the runway. The taxi-out time is hence defined as the time between off-blocks and take-off. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2017-03-31T14:27:07.210" LastActivityDate="2017-03-31T14:27:07.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9276" PostTypeId="2" ParentId="9274" CreationDate="2014-10-22T10:33:16.583" Score="7" Body="&lt;p&gt;The FAA definition is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=32f12d30db9d9064cf53135b34a77a39&amp;amp;node=se14.3.135_1100&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.100&lt;/a&gt; and the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;noreferrer&quot;&gt;pilot/controller glossary&lt;/a&gt; (quoted here):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TAXI- The movement of an airplane under its own power on the surface&#xA;of an airport (14 CFR Section 135.100 [Note]). Also, it describes the&#xA;surface movement of helicopters equipped with wheels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Interestingly, &amp;quot;pushback&amp;quot; is not in the glossary at all.&lt;/p&gt;&#xA;&lt;p&gt;This matches the Wikipedia definition that you mentioned, although not the ICAO one from DeltaLima. I think this definition makes sense, because taxiing doesn't necessarily have to be before a takeoff or after a landing. It's possible that the aircraft is simply taxiing from one point to another on the airport surface, e.g. from the fuel pumps to the hangar. That might be more common in GA, though: when I see airliners repositioning on the ground they're usually being towed.&lt;/p&gt;&#xA;&lt;p&gt;You also didn't mention air or hover taxiing, but I think it's fairly obvious in that case that the helicopter is under its own power. Here are the FAA definitions, for completeness, both from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;noreferrer&quot;&gt;P/CG&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;AIR TAXI- Used to describe a helicopter/VTOL aircraft movement&#xA;conducted above the surface but normally not above 100 feet AGL. The&#xA;aircraft may proceed either via hover taxi or flight at speeds more&#xA;than 20 knots. The pilot is solely responsible for selecting a safe&#xA;airspeed/altitude for the operation being conducted.&lt;/p&gt;&#xA;&lt;p&gt;HOVER TAXI- Used to describe a helicopter/VTOL aircraft movement&#xA;conducted above the surface and in ground effect at airspeeds less&#xA;than approximately 20 knots. The actual height may vary, and some&#xA;helicopters may require hover taxi above 25 feet AGL to reduce ground&#xA;effect turbulence or provide clearance for cargo slingloads.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-07T23:28:36.487" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9277" PostTypeId="1" AcceptedAnswerId="9283" CreationDate="2014-10-22T12:53:38.600" Score="15" ViewCount="1973" Body="&lt;p&gt;Recently, both Boeing and Airbus launched &quot;new&quot; aircraft as a modernized version of their respective best sellers (B737MAX and A320neo). To narrow the question down, I will consider the A320 and the FAA, but the same goes for the B737 and almost certainly many more aircraft families, and I hope for other certification authorities as well. I'm not really clear on the difference between type, model and series but I think the difference may be relevant for the certification process. Perhaps highlighting this difference is enough to answer the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia lists &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A318#Engines&quot; rel=&quot;noreferrer&quot;&gt;multiple variants of the A318&lt;/a&gt;. Do the A318-111 and the A318-121 require different certifications?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, when adding a variant to the family (here adding the A318 to the family composed of the A319, the A320, and the A321), do the certification authorities consider this aircraft as a totally new one or only as a variant of existing one (many shared components)? Can this consideration lighten the certification process?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the new version (A320neo) considered as a new aircraft by the certification authority and does it thus require the same set of tests as a new aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, when a new aircraft is an evolution or a variant of a previous one, how is it considered by certification authorities?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="4474" LastEditDate="2015-05-06T17:01:54.037" LastActivityDate="2015-05-06T17:01:54.037" Title="How are evolution and variants of aircraft considered by certification authorities?" Tags="&lt;aircraft-certification&gt;&lt;faa-approval&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9279" PostTypeId="2" ParentId="9277" CreationDate="2014-10-22T13:22:22.743" Score="14" Body="&lt;p&gt;Variants are seen as a modification of an existing airplane design, and only the changed parts need to be certified. The real advantage is that the set of rules the certification has to comply with are frozen at the time of the initial application, so any additional rules that had been added later are not relevant. This is called &quot;&lt;a href=&quot;http://www.usatoday.com/longform/news/nation/2014/06/14/unfit-for-flight-part-3/10533813/&quot; rel=&quot;noreferrer&quot;&gt;grandfather rules&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This definitely lightens the certification process and makes it less complex, but makes the safety enhancements, which were added after the type was certified first, optional for newly built airplanes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A318, A319 and A321 are all variants of the original A320, and the subtypes you name differ in their engine. Each engine option has to be certified separately, but all certification work not related to the engine can be shared between the variants. Additionally, the purchaser will select his options for instrumentation and furnishing, chosen from a limited set of previously certified options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a new version is introduced, the public will get a very different message from the airplane maker than the certification authorities. For the PR, the new variant is all new, but the FAA and the EASA will hear that almost nothing changed. In the end, it is similar to corporate profits: The shareholders get told the company made oodles of money, while the tax authorities will be presented with a bleak picture of mainly losses.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-05T20:07:19.763" LastActivityDate="2015-05-05T20:07:19.763" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9280" PostTypeId="2" ParentId="9252" CreationDate="2014-10-22T13:24:58.900" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;what causes a weight-controlled microlight to tumble&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There seem to be several mechanisms. One is an excessively sharp nose-down control input after entering or approaching a stall.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;and is it possible to stop it from tumbling once it starts?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not without an external safety device (presumably a throwable parachute or something similar)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The &lt;strong&gt;tumble mode is a little known mode of departure from controlled flight experienced by weightshift controlled microlight aeroplanes&lt;/strong&gt;. It has been a very significant factor in fatal accident records, being non-recoverable without the use of external safety devices. The mode consists of a nose-down autorotation at a rate of up to 400°/s. The tumble entry mechanism is explained, and advice to operators developed which should prevent tumble entry. Evidence is shown of the nature of the developed tumble – both modelled and through wind tunnel results, which explain how the autorotation occurs. It is also shown how this theory may be applied during testing of an aircraft to develop a tumble resistant aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://bura.brunel.ac.uk/handle/2438/708&quot; rel=&quot;nofollow noreferrer&quot;&gt;A theoretical and experimental appraisal of airworthiness evaluation techniques for small light aeroplanes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UDYuM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to be an excellent &lt;strike&gt;paper&lt;/strike&gt; &lt;em&gt;255-page dissertation&lt;/em&gt; which contains far far far more than the average reader of this website could ever want to know about this phenomenon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should note that this contains stills from the Youtube video in the question. It is therefore directly relevant. If you can find a better analysis I will print out my answer and eat it.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-22T13:51:34.853" LastActivityDate="2014-10-22T13:51:34.853" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9281" PostTypeId="2" ParentId="9277" CreationDate="2014-10-22T13:40:53.853" Score="6" Body="&lt;p&gt;First of all, the Certification Authority for Airbus is EASA, for Boeing it is the FAA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the A320 family. All variants, A318, A319, A320 and A321 of all series are on the same type certificate &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/EASA-TCDS-A.064_AIRBUS_A318,_A319,_A320,_A321_Single_Aisle-12-12092013.pdf&quot;&gt;EASA A.064(data sheet)&lt;/a&gt;. For the areas where these aircraft are different from the original A320, Airbus has demonstrated that they meet the requirements specified in the regulations. The A320neo will treated the as a new variant of the A320, so only the differences are tested for. Note that this is by no means a small task if you are introducing a number of significant changes which affect the performance of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The Boeing 737 type certificate is &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e038ae3ed2dbc2ae86257479004d1e57/$FILE/A16WE.pdf&quot;&gt;FAA.A16WE (datasheet)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-22T13:40:53.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9282" PostTypeId="2" ParentId="9274" CreationDate="2014-10-22T15:11:56.077" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;any movement on the ground including push-back&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This definition of taxiing is more specific to controllers. Once the aircraft has commenced its pushback it is normally infringing a controlled movement area and will be under the control of the ground or tower controller.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the movement of the aircraft on the ground under its own power and&#xA;  push-back is not considered taxiing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I believe this to be the more correct definition. Movement of an aircraft under its own power is important in a regulatory sense for aircraft operators. There are a number of matching definitions, relating to compliance with the Minimum Equipment List(MEL), ETOPs despatch - relating to weather minima and the definition of a sector, which is important for calculating the allowable flight duty period(FDP).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Definition of ETOPs Dispatch:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://easa.europa.eu/system/files/dfu/Annex%20II%20-%20AMC%2020-6.pdf&quot; rel=&quot;nofollow&quot;&gt;Extended range Twin Operations&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dispatch&#xA;  Dispatch is when the aircraft first moves under its own power for the purpose of taking-off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Dispatch is also used in relation to an aircraft meeting the requirements of the Minimum Equipment List (MEL) for a &quot;flight&quot;(defined below).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Definition of Sector&#xA;&lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP371.PDF&quot; rel=&quot;nofollow&quot;&gt;UK CAP371 Flight Time Limitations&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;'Sector'&#xA;  The time between an aircraft first moving under its own power until it next comes to rest after landing, on the designated parking position.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.jaa.nl/secured/Operations/OPS%20NAA/02%20Special%20Information/NPA%20MMELMEL-2.doc&quot; rel=&quot;nofollow&quot;&gt;Definition of Flight - ref to MEL&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Commencement of flight&quot; The point when an aircraft begins to move under its own power for the purpose of preparing for take off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-22T15:11:56.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9283" PostTypeId="2" ParentId="9277" CreationDate="2014-10-22T16:09:27.823" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm not really clear on the difference between type, model and series&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;type&lt;/strong&gt; is the basic airplane design, like the &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=1419&amp;amp;pagetype=90&amp;amp;pageid=1953&quot;&gt;A320 type&lt;/a&gt;, which includes the A318, A319, A320, and A321. A &lt;strong&gt;series&lt;/strong&gt; is the basic version of the type, like the A320-100 series. A &lt;strong&gt;model&lt;/strong&gt; is the specific configuration of the series, like the A320-111 model. The model may be mainly a different engine, or also include other changes specific to a customer.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do the A318-111 and the A318-121 require different certifications?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No. Airplanes are generally certified at the &lt;strong&gt;type&lt;/strong&gt; level, which also covers all series and models of that type. However, each new model &lt;em&gt;does&lt;/em&gt; have to be certified, which means it must be included in the applicable type certificate.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When adding a variant to the family, does the certification authority consider this aricraft as a totally new one or only as a variant of existing one?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As above, a new variant will generally be considered a new series within that family (type), and so will be included in the applicable type certificate.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is the new versions (A320neo) considered as a new aircraft by the certification authority and thus require the same set of test as a new aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As with new variants, new versions like the A320neo are &lt;em&gt;usually&lt;/em&gt; included in the same type certificate, but this can vary between authorities. For example, it looks like the UK's &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=1419&amp;amp;gid=1540&quot;&gt;CAA&lt;/a&gt; has separate type certificates for the 747-100/200 (FA5) and the 747-400 series (FA44). The &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet&quot;&gt;FAA&lt;/a&gt; (A20WE) and &lt;a href=&quot;http://easa.europa.eu/document-library/type-certificates/easaima196&quot;&gt;EASA&lt;/a&gt; (EASA.IM.A.196) have one certificate for the whole 747 series.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The level of work required to certify a new model or series depends on the degree of differences from the previously certified configurations. If something was previously certified, then this will probably apply on the new model. Of course there will be more differences for a new type than just a series, especially when changing other aspects of the design, as with the A320neo. The decisions on what needs additional work to certify are specific to each situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have mentioned, there are multiple certifiying authorities around the world. An aircraft is first certified with the authority in the country of manufacture (EASA in Europe, FAA in the US, CTA in Brazil, etc.). When an aircraft is to be operated in another country, to avoid restrictions on operation, the authority in that country must also certify the aircraft. The authorities tend to have agreements with each other to make this process easier.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-22T21:02:30.530" LastActivityDate="2014-10-22T21:02:30.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9284" PostTypeId="2" ParentId="9268" CreationDate="2014-10-22T16:23:51.247" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How reliable are stick shakers? Should they always be trusted?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think the answer to this is can be covered by one of the great aviation mantras:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&quot;always trust your instruments&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is drilled into you when learning to fly on instruments. Pilots very rarely rely solely on one source of information. If you get a stick shaker, you'll normally immediately look for the reason as part of your scan. Stall warnings are rare in large aircraft but you sometimes get transient warning, e.g. when an aircraft is in turbulence or at low speed with a higher angle of attack and manoeuvring. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew of AF447 had a number of conflicting indications in the flight deck and were relying on the protection system of the aircraft to prevent the stall. Sadly the aircraft ended up stalled as the protection systems were not functioning correctly due to an erroneous air data source. One of the pilots held positive back pressure on the controls which maintained the stall condition of the aircraft. The recovery from the stall in large aircraft is the same as any with the most important part - &lt;strong&gt;Lower the nose&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good article by Boeing &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_03/textonly/fo01txt.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Stick pushers&lt;/strong&gt; are rare now as aircraft designers tend to shy away from producing aircraft which require one. Aircraft such as the HS Trident had stick pushers as they could end up in a &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_(fluid_mechanics)#Deep_stall&quot; rel=&quot;nofollow&quot;&gt;deep stall&lt;/a&gt;&lt;/strong&gt; - which is unrecoverable flight condition.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-22T16:23:51.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9285" PostTypeId="1" CreationDate="2014-10-22T19:08:11.900" Score="5" ViewCount="1107" Body="&lt;p&gt;Her teacher asked this question to my niece (8 years old)? However I couldn't find a solid answer either. In which part of the flight, the effect of the air resistance (drag) is more important? Takeoff, cruise, descent or landing?&lt;/p&gt;&#xA;" OwnerUserId="4022" LastActivityDate="2014-10-23T17:16:32.803" Title="During which part of the flight the effect of air resistance is more important?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;cruise&gt;&lt;descent&gt;&lt;drag&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9286" PostTypeId="2" ParentId="9285" CreationDate="2014-10-22T19:17:46.283" Score="2" Body="&lt;p&gt;Anytime air is moving over the surfaces of the aircraft, drag is important.  There really isn't a time when it's &quot;more&quot; important.  When an aircraft wants to move, during any phase of flight, the thrust of the craft must exceed the drag the air (or wheels, on the ground) is creating on the craft.  At any point that the aircraft is flying, the drag must be overcome to the point that the wings can create the required lift to get the aircraft into the sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps, though, the question actually had to do with &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_brake_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;air brakes&lt;/a&gt;?  When those are deployed the amount of drag created is increased by quite a lot, slowing the aircraft by quite a bit.  And as a result air brakes are often used during the descent phase of flight in order to keep the plane from accelerating to much as it approaches the runway.  Perhaps that's what the teacher is after...&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-10-22T19:17:46.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9287" PostTypeId="1" AcceptedAnswerId="9292" CreationDate="2014-10-22T19:27:40.627" Score="14" ViewCount="43453" Body="&lt;p&gt;I was told at one point that the sweep of a wing can help with the straight line stability of the craft, in fact I think it's one of the main systems that keeps flying wings flying straight (like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot;&gt;B-2&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_N-9M&quot;&gt;N9-M&lt;/a&gt;, which comes from the 40s, way before the use of flight computers for stability...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is that?  Are there trade offs between that stability and say, speed?  Is there a such thing as too much sweep?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="23223" LastEditDate="2019-09-12T09:54:26.270" LastActivityDate="2019-09-12T09:54:26.270" Title="How does wing sweep increase aircraft stability?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;stability&gt;&lt;flying-wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9288" PostTypeId="2" ParentId="9285" CreationDate="2014-10-22T20:26:34.560" Score="6" Body="&lt;p&gt;The answer they are looking for is probably &lt;strong&gt;cruise&lt;/strong&gt;. This is generally the longest part of the flight, so the losses from drag will add up. Most aircraft are optimized as much as possible to have good performance in cruise to save fuel and meet range requirements, so having low drag is more important in this part of the flight than others. This is also generally the section where the aircraft is traveling fastest. &lt;a href=&quot;https://aviation.stackexchange.com/a/9294/1696&quot;&gt;As Peter Kämpf showed&lt;/a&gt;, drag is highest at higher speeds, other than periods where landing gear, flaps, etc., are extended and add more drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/9286&quot;&gt;As Jay Carr explained&lt;/a&gt;, drag is important at every point while the aircraft is in the air, affecting different areas of performance. During takeoff, drag will affect the runway distance needed, and initial climb performance. Low drag during descent is helpful, unless you need to get down faster, like in an emergency descent. Drag is probably highest during landing, because the emphasis is placed on having as much lift as possible at slower landing speeds, and this lift is created at the expense of higher drag.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-10-23T17:16:32.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9289" PostTypeId="2" ParentId="9287" CreationDate="2014-10-22T20:54:25.050" Score="1" Body="&lt;p&gt;A big benefit of swept wings is lower drag at high speed. When an aircraft with swept wings yaws, it is effectively increasing the sweep of the wing in the direction of the yaw, and decreasing the sweep of the other wing. So the wing opposite the direction of yaw will have less sweep, therefore more drag, counteracting the yaw. Likewise, the other wing will have higher sweep and less drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course you can have too much sweep, otherwise all planes would just sweep their wings completely away and look like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Martin_Marietta_X-24A&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-24&lt;/a&gt;. Your previous question addresses other properties of swept wings well:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1726/variable-wing-sweep-on-military-craft&quot;&gt;Why do some military aircraft use variable-sweep wings?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are certainly tradeoffs, but vertical surface area is still a more effective means of providing stability. The effect on swept wings of 1 degree of yaw will be less than the force created from the rear fuselage (and vertical stabilizer) being at effectively 1 degree angle of attack. Of course flying wings will primarily rely on this differential drag for stability, but they use things like clamshell brakes to create the necessary drag for extra stability and control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More sweep is better for speed, but not so good if you want to go slower. So sweep is going to limit low speed performance, and the stability improvement will also be less as airspeed decreases.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-10-22T20:54:25.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9290" PostTypeId="2" ParentId="9287" CreationDate="2014-10-22T21:13:14.257" Score="2" Body="&lt;p&gt;As for flying wings, longitudinal control (let alone stability) depends on being able to being able to move the center of lift backwards and forwards. That would be hard to do with a straight flying wing which doesn't have a separate tailplane or carnard -- all the lift is generated at the same (longitudinal) position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if your flying wing has sweep, you can get longitudinal control by putting control surfaces at different distances from the center of the aircraft. Increasing lift at the outer parts of the wing will produce a nose-down moment, and vice versa.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-10-22T21:13:14.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9292" PostTypeId="2" ParentId="9287" CreationDate="2014-10-23T05:05:43.967" Score="22" Body="&lt;h2&gt;&lt;em&gt;Directional stability&lt;/em&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When a swept wing is flying in a sideslip, the windward side behaves like a wing with less effective sweep $\varphi_{eff}$ and the leeward side like one with more effective sweep. Wing sweep  causes a flattening of the lift curve slope for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The effective angle of attack is reduced by the cosine of the sweep angle.&lt;/li&gt;&#xA;&lt;li&gt;Only the component of speed normal to the quarter-chord line of the wing is creating lift, so a swept wing creates less lift per area than a straight wing.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xdpbx.png&quot; alt=&quot;SB-13 in sideslip&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The increased lift rolls the aircraft, but also produces increased lift-induced drag which pulls it back to straight flight. The sketch above shows this for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Akaflieg_Braunschweig_SB-13_Arcus&quot; rel=&quot;noreferrer&quot;&gt;flying wing glider SB-13&lt;/a&gt;. This effect is so strong that swept, high-wing configurations need anhedral to keep the sideslip-induced rolling moment down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For completeness, also the side force $Y$ of fuselage and winglets is added and shows that the winglets help a lot to create directional stability. This is needed in case of the SB-13 because it has a nearly elliptical lift distribution. Using a triangular distribution (N9-M) or even a bell-shaped distribution (&lt;a href=&quot;http://en.wikipedia.org/wiki/Horten_brothers&quot; rel=&quot;noreferrer&quot;&gt;Horten&lt;/a&gt; flying wings) avoids the need for winglets, but causes higher induced drag in straight flight. Another downside is a low directional stability at high speed, because this sweep effect increases with the lift coefficient on the outer wing.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;em&gt;Longitudinal stability&lt;/em&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Wing sweep also helps in longitudinal stability by stretching out the wing lengthwise. This is important for flying wings which lack a separate tail surface. By changing flap angles at the center or the wing tips, the lift at the most forward or most backward sections can be changed for pitch control, and more sweep increases the lever arm of these changes. Also, in swept flying wings natural static stability can be achieved without the use of reflex airfoils, but by applying washout. Again, the higher the sweep angle, the less washout is required.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;em&gt;Too much sweep?&lt;/em&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Easily! Sweeping a wing creates lots of problems:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Sweep reduces the lift curve slope and the maximum lift of a wing. The maximum landing attitude with a highly swept, slender wing is severely limited by wing tip clearance, so swept wings need powerful high-lift devices.&lt;/li&gt;&#xA;&lt;li&gt;Sweep causes the boundary layer to be washed outboard, which will cause nasty stall behavior once a specific ratio of wing aspect ratio and sweep has been exceeded. This can be somewhat limited by wing fences, but should better be avoided altogether.&lt;/li&gt;&#xA;&lt;li&gt;Sweep changes mean that bending moments will partially get converted to torsion moments, requiring a torsional stiffening of the wing.&lt;/li&gt;&#xA;&lt;li&gt;For flying wings, sweep will let the aircraft center pitch up and down when the wing flexes. This creates a powerful interaction between the fast period mode (which is only moderately damped in flying wings) with the wing bending mode, resulting in flutter.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;&lt;em&gt;Why sweep a wing at all?&lt;/em&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Generally, an aircraft designer will allow only as much sweep as necessary. &#xA;Wing sweep reduces drag when the aircraft flies with transonic or supersonic speed. Now the Mach effects depend only on the normal speed component, so they are proportional to the cosine of the sweep angle. For the N9-M this was not a factor, however, the B-2 benefits from it with a higher &lt;a href=&quot;http://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;drag divergence Mach number&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-23T19:45:49.320" LastActivityDate="2014-10-23T19:45:49.320" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9293" PostTypeId="2" ParentId="9285" CreationDate="2014-10-23T06:43:30.750" Score="1" Body="&lt;p&gt;Drag (Air resistance) plays a part in all phases of flight, its most critical during takeoff or landing as this is when it will have the most drastic/immediate effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would pick landing as my favourite for the answer and as it is the most apparent, with all the bits of metal hanging from the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft slows it lowers the leading edge slats(if fitted) and trailing edge flaps to increase the amount of lift the wing is able to produce, as you increase the lift you are also increasing the drag. In jet aircraft the spoilers are often used to assist this reduction in speed or to maintain/increase the rate of descent whilst decelerating(not easy in a heavy jet with lots of inertia). At some point during the approaching (normally around 2000ft ish) you have to lower the gear, which again adds to the drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this drag on approach allows the engines to spool up, which is useful on large turbine aircraft as it means the engine is at a good state to provide power quickly in the event of a missed approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On touch down the configuration changes again - the spoilers deploy, reverse is selected and as the nose lowers the wheel brakes kick in - lots of drag (ok, the wheel brakes don't provide air resistance, but they are a fairly large part of the decel process). The spoilers drastically reduce the lift of the wing pushing the aircraft down onto runway meaning the brakes have the greatest effect. Some aircraft at this point change the flap configuration, in light aircraft its an option to retract the flap which reduces the lift on the wing making the brakes more effective. Other types lower more flap, having a &quot;barn door&quot; type effect. The Boeing 747 retracts the inboard section of slat, which again helps reduce the lift on the largest part of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As all this is happening thrust is redirected forward and power is increased on the engines helping the deceleration down to around 80-60kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft (normally fighters) you hold the nose off the runway on landing to increase drag, braking aerodynamically down to a low speed. In commercial aircraft you normally lower the nose as the wheel brakes have greater effect (you normally have a lot more main wheels/brake units than fighter types). &lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-10-23T06:43:30.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9294" PostTypeId="2" ParentId="9285" CreationDate="2014-10-23T07:00:59.187" Score="3" Body="&lt;p&gt;The question leaves a lot of room for interpretation, so here is my version:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume a constant mass of the aircraft, resistance varies with speed, and there is a minimum relative to the lift force when the lift-induced and zero-lift drag components are equally large. You can now argue that air resistance (however defined) is &lt;strong&gt;least&lt;/strong&gt; important at that speed and becomes more important at low and high speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IqqyP.png&quot; alt=&quot;Glider drag components&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot shows the drag components of a typical glider in straight flight, but if you adapt speeds and forces, the same plot works for any other airplane. It shows that the drag (= air resistance) is highest at the highest flight speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-23T07:00:59.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9297" PostTypeId="1" AcceptedAnswerId="9298" CreationDate="2014-10-23T12:34:26.667" Score="8" ViewCount="3103" Body="&lt;p&gt;Is there any way to identify whether an airport has PAPI lights (2-light or 4 light system, doesn't matter)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am working on some map generation and using aerial images to identify PAPI lights for airports. I was wondering if there is any quicker way to identify visual whether PAPI lights exisit on airport runways.&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="19" LastEditDate="2016-07-15T14:12:00.893" LastActivityDate="2016-07-15T16:46:07.673" Title="How to know if an airport has PAPI lights?" Tags="&lt;airport&gt;&lt;runways&gt;&lt;papi&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9298" PostTypeId="2" ParentId="9297" CreationDate="2014-10-23T12:50:14.437" Score="8" Body="&lt;p&gt;Whether an airport has PAPI lights or not is indicated on the approach charts. For instance &lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/aip/enligne/PDF_AIPparSSection/VAC/AD/2/1412_AD-2.LFCL.pdf&quot;&gt;on this chart&lt;/a&gt;, there is a schematic of the airport at the bottom of page 3 that shows you where the PAPI is on the airfield. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking for airports in France, you can find all visual approach charts on the &lt;a href=&quot;http://www.sia.aviation-civile.gouv.fr/html/frameset_aip_fr.htm&quot;&gt;government website&lt;/a&gt;. &#xA;Otherwise, &lt;a href=&quot;http://wiki.flightgear.org/Getting_aeronautical_charts&quot;&gt;this wiki&lt;/a&gt; has various links to approach chart ressources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: If there is not indication concerning the location of the PAPI on the approach chart, you can refer to page 40 of &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FINAL%20FAA%20Order%206850.2B.pdf&quot;&gt;this FAA document concerning visual aids&lt;/a&gt;. The schematic here describes the standard location of the PAPI relatively to the strip. &lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2014-10-23T14:05:26.237" LastActivityDate="2014-10-23T14:05:26.237" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9299" PostTypeId="2" ParentId="9270" CreationDate="2014-10-23T13:53:03.603" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;3) Is there a freeware solution to this? I'm more interested on&#xA;  information like the geography, cities, countries and borders.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't think you'll find many freeware solutions in commercial aviation, but who knows. If you are interested in geography, cities, countries and borders I wouldn't buy an inflight entertainment system though. That kind of information is freely available on the internet. Google maps or Google Earth would give that info for example. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1) The software from various airline companies seems to be more or&#xA;  less of a standard. So they should work in a similar fashion. Which&#xA;  input is needed in order to make it work (i.e., altitude, lat/lon&#xA;  coordinates, temperature)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For the route display: departure airport, destination airport, optionally a&#xA;number of waypoints. Estimated time of arrival, actual time of departure.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For the current position: latitude, longitude,&#xA;altitude and heading.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Also provided: velocity, air temperature, wind speed &amp;amp; heading.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Typically these inputs are provided over multiple &lt;a href=&quot;http://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow&quot;&gt;ARINC 429&lt;/a&gt; busses from the Flight Management Computer and Air Data Computer, but RS-232 systems exist as well. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2) Is it possible to acquire one version of this software and run it&#xA;  offline as a simulation, giving as input the needed information?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't think you can buy the software on its own, you'll have to buy the hardware too. That is going to expensive, but you can buy an in-flight entertainment system and provide it with the proper inputs. Quite a big project I think. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-23T13:53:03.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9300" PostTypeId="2" ParentId="9243" CreationDate="2014-10-23T14:10:58.840" Score="1" Body="&lt;p&gt;Parachute rescue system is available on smaller airplane, like Pipistrel Panthera, and latest Cirrus SR22/SR22T. Your scenario looks nice, but probably not practical enough to be installed on larger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4034" LastActivityDate="2014-10-23T14:10:58.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9302" PostTypeId="2" ParentId="9274" CreationDate="2014-10-23T14:31:58.303" Score="-1" Body="&lt;p&gt;The time you leave the apron (GATE/RAMP position) and arrived at your takeoff strip (Piano key-marked Takeoff zone), the journey in between is well-known as taxiing. I am sure that this is correct because I have experience with runways and aircrafts. It's a common sense that taxii means no ground power/air cart, and also no support. You taxi your way to the takeoff zone. No disupte about this.&lt;/p&gt;&#xA;" OwnerUserId="2695" LastActivityDate="2014-10-23T14:31:58.303" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9303" PostTypeId="2" ParentId="9297" CreationDate="2014-10-23T16:31:44.727" Score="6" Body="&lt;p&gt;For airports in the USA, I'd look in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow&quot;&gt;Chart Supplement&lt;/a&gt; (formerly known as the Airport/Facility Directory). It lists characteristics of each runway, including lighting. Here's one for KEAU, where I did my primary flight training:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;RWY 22: MALSR. PAPI(P4L)—GA 3.0º TCH 50´. 0.6% down.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Note that this runway has a 4-light PAPI on the left side of the runway. From the legend:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;P4L 4–identical light units placed on left side of runway&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="520" LastEditorUserId="520" LastEditDate="2016-07-15T16:46:07.673" LastActivityDate="2016-07-15T16:46:07.673" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9304" PostTypeId="2" ParentId="9270" CreationDate="2014-10-23T18:35:06.657" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;1) The software from various airline companies seems to be more or&#xA;  less of a standard. So they should work in a similar fashion. Which&#xA;  input is needed in order to make it work (i.e., altitude, lat/lon&#xA;  coordinates, temperature)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&quot;Inputs&quot; from the aircraft devices, like pitot, anemometer, gyro, etc. ? I don't know. DeltaLima answered that for you. What you see on the screen is definately a &lt;strong&gt;software rendering&lt;/strong&gt;, that means an operating system is running, and displays a frame on that screen device. The graphic is &lt;strong&gt;software-generated&lt;/strong&gt; (the map, the plane, its orientation, the text, the sun, the clouds, zooming, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, at some point, the &lt;strong&gt;inputs&lt;/strong&gt; signals (altitude, cruise, heading...) has to be converted in computer bytes that will be handled by hardware devices of a computer, buffered in memory, then used by &lt;em&gt;&quot;some software&quot;&lt;/em&gt; in the way they have been designed for.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Option 1 :&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There's a central Operating System (OS) that holds all the computable datas and feeds all onboard software on demand including FMS, IFE, etc.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;analogic device -&amp;gt; convert to computable data (bytes) -&amp;gt; central OS&#xA;                                                        / | \&#xA;                                                      /   |   \&#xA;                                                    /     |     \&#xA;                                    Cockpit softwares    IFE    Cabin Softwares&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;h2&gt;Option 2 :&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There's no central OS, but multiples ones, and a direct star-type (tree) data pipeline.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;analogic device&#xA; |_ convert to computable data (bytes)&#xA;     |_ some software on some OS&#xA;     |_ some software on some OS&#xA;     |_ IFE softwares on IFE OS&#xA;     |_ some software on some OS&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;h2&gt;Option 3 :&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;IFE Software is a included in one OS that also run other softwares&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;analogic device&#xA; |_ convert to computable data (bytes)&#xA;     |_ OS1 (cabin)&#xA;     |   |_ IFE softwares&#xA;     |   |_ Inflight intercom software&#xA;     |_ OS2 (cockpit)&#xA;     |   |_ Front Panel softwares&#xA;     |   |_ BlackBoxes softwares&#xA;     |_ HUD software (of packed software in hardware)&#xA;      ...&#xA;      ...&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;There are other Options, each one could be better called &quot;onboard System&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, if, by &lt;em&gt;&quot;inputs&quot;&lt;/em&gt;, you meant &lt;em&gt;&quot;how to make that tiny plane move along the map&quot;&lt;/em&gt;, there are thousands of ways doing it, but the schemas is the same :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;draw a map (use some gree/blue/brown color to make it look good enough)&lt;/li&gt;&#xA;&lt;li&gt;draw a path using points locations on a X-Y (invisible) grid and line segments&lt;/li&gt;&#xA;&lt;li&gt;slam a top view of a plane on all of that at a precise X-Y location (and don't forget to rotate the plane icon in the correct heading or your passengers will start to panick)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;No matter how beautiful the flightpath could be rendered, remember it's a computer generated graphic, and doesn't need to be accurate at all. For example, refreshing could be set at an interval of 5 seconds instead of real time (5 seconds is good enough even for steep turns on final) The map resolution doesn't require a milimetric precision. 1000ft or 500ft lateral precision could suffice, and &lt;em&gt;even if the displayed (text) altitude is in feet&lt;/em&gt;, the 3D rendering doesn't care about that at all : it uses a fraction of that altitude, then accordinly shifts the position of the aircraft model on the screen to give you the impression the aircraft is at an higher altitude...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That the logical way the flightpath software requires. Accuracy and physics computations are not required, unless you want to create a game or even better, a simulator (in terms of reproducing nearly-real behaviour in a virtual world) GoogleEart's Flight game for example isn't as precise as many other games out there (Lock On, X-Plane...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for all of those, the &quot;inputs&quot; are all binary datas stored in memory and used as variables by the software. Turning a plane isn't dependent on a heading value. It's one block of the software code that reads the heading variable, then rotate the object (the plane) by the corresponding angular value, then another block of the software code draws (renders) the object on a screen buffer. Finally, the screen buffer is passed to the displaying device (your IFE screen) and each pixel of that screen shows what has been calculated by the software for the human eyes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, what you see on a screen - &lt;em&gt;ANY&lt;/em&gt; screen wether it's your TV, the IFE, your computer screen when you read this answer, your phone screen - is a series of slideshows pictures rendered by the screen device one image after another. But it's done so fast that the human eyes (or brain actually) think what is shown is really moving. It's not, but looks like.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2) Is it possible to acquire one version of this software and run it&#xA;  offline as a simulation, giving as input the needed information?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I tend to say yes ! but wait !&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Good luck&lt;/strong&gt; finding that software though. You should ask someone working for an IFE system provider for aircraft manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And note one thing : Such softwares could be packed in some hardware components having an inbuilt memory card, this preventing anyone from copying that very software while it is successfully loaded in the IFE OS just like any other software loaded from disk/CDs/USBs... Of course you can't unplug the hardware device from the IFE hardware motherboard, and plug it on your computer motherbord, that wont make it.. Just like your phone (wether android or iphone or whatever) the firmware is burried deep in one hardware component. You can't easily copy a firmware from an iphone to a nexus.. :P &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But at one point, those softwares has to be created on a computer, then, have their &quot;saved as files&quot; state in the computers of the enterprises creating them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you could have guessed, chances to get a copy of such software is pretty.. non existent, not because it's nearly impossible, but because such software are copyrighted, and/or the (hardware) system supposed to work with aswell. A flightpath IFE software developped by a company may fail to work on your computer if you don't have the same OS architecture as the company's, and/or even some hardware devices that may be required to input or output valid binary datas read/written by the software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone who has a copy of such software wont tell you he has...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can tell you the &lt;code&gt;Air Austral&lt;/code&gt; IFE is Linux based Operating System. The flightpath map displayed, the movies/music/games entertainments are all running on that OS. While the IFE on some &lt;code&gt;Air Madagascar&lt;/code&gt; planes could be Linux based aswell, the softwares (the rendering and graphic layout) are different, meaning that those are not the same softwares as the Air Austral ones (or other versions)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3) Is there a freeware solution to this? I'm more interested on&#xA;  information like the geography, cities, countries and borders.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An authentic flightpath software like those onboard aircraft ? &lt;strong&gt;Nope !&lt;/strong&gt; Never seen one in the items library of a store, and never found a page using google of a page &quot;FlightPath Software Download&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A software that shows earth, oceans/lakes, country boundaries maybe ? &lt;strong&gt;Yes !&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GoogleEarth/GoogleMaps&lt;/li&gt;&#xA;&lt;li&gt;Nasa Worldwind&lt;/li&gt;&#xA;&lt;li&gt;Bing Maps&lt;/li&gt;&#xA;&lt;li&gt;Many little and less widely used software on SourceForge using rendering libraries and web hosted databases&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A software that allows you to draw/show paths (and objects if possible)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GoogleEarth&lt;/li&gt;&#xA;&lt;li&gt;Cesium&lt;/li&gt;&#xA;&lt;li&gt;Nasa WorldWind&lt;/li&gt;&#xA;&lt;li&gt;Marble&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A standalone software that shows you (simulated) realtime flight of an aircraft over a map or 3D Earth ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone who tried creating such software ended making it a web-based application that you can access only through a navigator (like FlightRadar) Otherwise, it would be the decision of an enterprise or organism to hire developpers to produce such software for internal business purposes ONLY !&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;display aircraft on a radar screen&lt;/li&gt;&#xA;&lt;li&gt;display meteorogical objects evolution on a map&lt;/li&gt;&#xA;&lt;li&gt;display satellites movements at a space center on a large screen&lt;/li&gt;&#xA;&lt;li&gt;(^^ purposes like that that has nothing to do in public domain)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's exactly what IFE hardwares/softwares is about : have a bunch of engineers/programmers, build the devices/softwares, sell them to airlines/aircraft manufacturers. Panasonic, Thales, LiveTV of JetBlue, Rockwell Collins... Don't expect them to upload their baby on a website and allow you to download them..&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So far, I said &quot;anyone who tried...&quot; ... ... &lt;strong&gt;failed&lt;/strong&gt; ! Because building such software, to be accurate enough &lt;strong&gt;and interresting for you and me&lt;/strong&gt;, would require a massive amount of datas :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;flightpaths are not straight lines from airport to airport. You can spot this with FlightRadar, then you'll need each airport data, with their SID/STARS; you'll need waypoints, you'll need routes (those you can see on a real jepessen map) etc.&lt;/li&gt;&#xA;&lt;li&gt;of course, you'll have to maintain those datas up to date.&lt;/li&gt;&#xA;&lt;li&gt;those datas &lt;strong&gt;are NOT freely&lt;/strong&gt; available, so if you're a developper that paid acquiring them (or a company that employs developpers) you should find a way to make profit on it. That's what Microsoft made with Flight Simulator, what Lockheed Martin is doing with Prepar3d, X-Plane, etc. Games are selling well, but a simple &lt;em&gt;&quot;show my flight plan&quot;&lt;/em&gt; software isn't interresting enough to make profit on it. For you or me perhaps, but not at all for average people.&lt;/li&gt;&#xA;&lt;li&gt;And because the datas has to be updated, a standalone application that doesn't connect to the web would prove impossible to achieve, as it will be obsolete soon enough and would require anyway an internet connexion and mostly a registering (payware) for stream updates. Most applications that does this are web-based applications, &lt;strong&gt;not downloadable&lt;/strong&gt; ! This is even more not standalone if you are thinking of displaying an actual, flying, aircraft (like FlightRadar) - And you'll have to purchase access rights on some radar centers... and implement the programatic logic to handle those streams of datas at runtime.&lt;/li&gt;&#xA;&lt;li&gt;What about maps ? If the plane is flying above the city of New-York, what are you going to display ? A greenish-brown landscate ? A text showing &quot;New-York&quot; ? What about the shores (or how the software knows there is nearby ocean and land ?) Yes, you must have a landclass/waterclass database. The way the datas are stored highly depends on the way the software displays them. You need raster (images) tiles of the earth if you want photoreal-like terrain, or vector-based datas for computer generated landscapes. The later is lighter in terms of required disk space, but vector-based datas ar good for flat terrains (projections) To have datas for mountains, valleys, etc. you'll need anyway discrete values of land elevation around the globe. The disk space used quickly rockets... So don't expect from someone the task to compile all those datas for you.. and there are awfull voids here and there (in far far away land on this earth) that you can't retrieve freely on the web (well, there are 100 meter resolution terrain elevations available for free out there, but higher resolutions are very hard to get for the entire planet)&lt;br /&gt;&#xA;That's why on flightplans IFE, you can't zoom in and see roads on the map ;) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I've started developping my own &lt;em&gt;&quot;show aircraft routes and display realtime flying tiny aircraft over a map&quot;&lt;/em&gt; years ago, still, &lt;strong&gt;it's stucked as a &lt;em&gt;&quot;Work In Progress&quot;&lt;/em&gt;&lt;/strong&gt; due to the massive amount of new issues occuring and the interlacing complex features I would like it to have (Compatible with the game simulators mentionned above)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's almost one new created airline every week, one new aircraft delivered every day, updating the - &lt;em&gt;offline&lt;/em&gt; - database of that program occurs on a daily basis, weekly at longest, and I still need internet for that ! So, the day I may release that application would never come before I die. Just to pick an example, the application is developped as a Windows Forms interface. There's a better interface provided by the dotNet Framework called WPF. Upgrading the application to this new architecture would be a must before releasing it, and I have no time to do that. The database weight several Gigabytes (as expected : Maps and graphics...)&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="3879" LastEditDate="2014-10-23T18:49:58.847" LastActivityDate="2014-10-23T18:49:58.847" CommentCount="7" CommunityOwnedDate="2014-10-23T18:35:06.657" ContentLicense="CC BY-SA 3.0" />
  <row Id="9306" PostTypeId="1" AcceptedAnswerId="9309" CreationDate="2014-10-24T12:36:53.880" Score="18" ViewCount="17514" Body="&lt;p&gt;Flight schedules are based on the local time of the station of departure or arrival. Twice a year though, this is either ambiguous or impossible. What happens on these boundaries?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say, for instance, a flight is scheduled for departure daily at 1:30 A.M. This year, DST ends at November 2nd, 2 A.M., meaning the local clock will go from 2 A.M. back to 1 A.M. Will this flight depart on the first 1:30 A.M. or the second?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the other way round, say next year a flight is scheduled for departure daily at 2:30 A.M. When DST starts, the clock will go directly from 2:00 A.M. to 3:00 A.M. and 2:30 doesn't exist. What happens for this flight?&lt;/p&gt;&#xA;" OwnerUserId="4043" LastEditorUserId="572" LastEditDate="2015-02-24T10:54:06.550" LastActivityDate="2019-01-31T17:18:38.580" Title="How are flight schedules displayed without ambiguity on DST change days?" Tags="&lt;flight-schedules&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9307" PostTypeId="1" CreationDate="2014-10-24T12:41:56.123" Score="2" ViewCount="226" Body="&lt;p&gt;As mentioned on &lt;a href=&quot;http://en.wikipedia.org/wiki/Pan_Am_Flight_103#Investigation&quot; rel=&quot;nofollow&quot;&gt;Pan Am Flight 103&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... In total 4 million pieces of wreckage were collected and registered on&#xA;  computer files. More than 10,000 pieces of debris were retrieved,&#xA;  tagged and entered into a computer tracking system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is a bit confusing, at least to me. So which one is the actual number? Or if both sentences are correct, what is the difference between them?&lt;/p&gt;&#xA;" OwnerUserId="4044" LastEditorUserId="19" LastEditDate="2015-04-02T17:26:46.867" LastActivityDate="2015-04-02T17:26:46.867" Title="Lockerbie bombing - amount of debris (confusing numbers)" Tags="&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2014-10-31T01:57:20.997" ContentLicense="CC BY-SA 3.0" />
  <row Id="9308" PostTypeId="2" ParentId="9307" CreationDate="2014-10-24T13:31:28.867" Score="-2" Body="&lt;p&gt;Pieces of wreckage implies a large 'section' of plane, whereas debris suggests miscellaneous smaller items and bits of metal etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I agree it's potentially confusing, however, and likely arises from two people editing the same section without adjusting the context.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd say that 4 substantial sections of plane were found, along with a large amount of smaller debris scattered around, totalling around 10,000 pieces.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-10-24T13:31:28.867" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9309" PostTypeId="2" ParentId="9306" CreationDate="2014-10-24T13:35:21.347" Score="13" Body="&lt;p&gt;It's only really ambiguous once a year, when moving from summer time to winter time and the hour is 'repeated' - in this case, departures and arrivals are scheduled in the 'first' instance of the hour: eg if the flight is scheduled 01:30, it will depart 1.5 hours after midnight. The clock will then go back eg at 2am, and the airport will be relatively for one hour with no departures (although, of course, arrivals may still come in)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other shift, the hour is 'lost' so the departure takes place later. In practice, no planes are scheduled to arrive or depart in this missing hour, and since almost all nations make the change in the middle if the night when airspace is very quiet and most airports have no departures at all there is virtually no knock-on effect. Arrivals arrive when they arrive, departures are simply scheduled for a 'real' hour, if there are even departures at all at that time of day anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this is only for passenger scheduling - in air traffic control etc all times are Zulu (UTC) which has no ambiguity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TL;DR: Fall/Autumn, aircraft depart in the &quot;first&quot; instance of the hour. Spring: scheduling works as usual, but with no flights scheduled in the &quot;missing&quot; hour (eg 2-3am)&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2019-01-31T17:18:38.580" LastActivityDate="2019-01-31T17:18:38.580" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="9310" PostTypeId="2" ParentId="9306" CreationDate="2014-10-24T14:23:09.250" Score="7" Body="&lt;p&gt;Daylight Savings does not cause ambiguity in flight schedules, even though it may appear to.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Basic Concepts&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Before discussing your specific scenarios, let's look at some concepts.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;First of all, not all countries observe DST. The ones which do, may not observe it for the same period either. Hence, airlines know if and when the destination region&lt;sup&gt;1&lt;/sup&gt; observes DST.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A flight's duration does not change because of DST. If an airplane takes 5 hours to reach its destination, it won't take 4 or 6 hours because DST is turned on or off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airlines and related entities (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC&lt;/a&gt;) use times &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot; rel=&quot;nofollow noreferrer&quot;&gt;UTC&lt;/a&gt;, especially when an airplane is crossing a timezone, to reduce confusion. Pilots and ATC personal are used to follow UTC times without any difficulty. UTC does not observe DST.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When a timezone observes DST, they change the timezone code too. For example, instead of &lt;a href=&quot;http://en.wikipedia.org/wiki/Eastern_Time_Zone&quot; rel=&quot;nofollow noreferrer&quot;&gt;EST&lt;/a&gt; (Eastern Standard Time), they'll use EDT (Eastern Daylight Time).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When DST ends, clocks are moved from &lt;a href=&quot;http://en.wikipedia.org/wiki/Daylight_saving_time#Procedure&quot; rel=&quot;nofollow noreferrer&quot;&gt;3AM to 2AM&lt;/a&gt;, not from 2AM to 1AM.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JIjJn.png&quot; alt=&quot;DST Ending&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Your Questions&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now, let us talk about the scenarios you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If a flight is departing at 2:30AM (time corrected as I mentioned above), it will depart most probably on the first 2:30AM. Flights have their schedules mentioned in UTC as well, so it will not a confusion. &lt;em&gt;As I do not know everything, I have never seen a flight departure time in that particular hour. Would you care to share an example?&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If a flight is arriving at &lt;em&gt;supposedly&lt;/em&gt; 2:30AM on the day when DST is starting, it &lt;strong&gt;will not&lt;/strong&gt; arrive at 2:30AM but at 3:30AM. Because, as you said, 2:30AM does not exist on that day for that timezone.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Examples&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/9306/flight-schedules-on-dst-boundaries#comment17346_9310&quot;&gt;suggested&lt;/a&gt; by &lt;a href=&quot;https://aviation.stackexchange.com/users/1696/fooot&quot;&gt;fooot&lt;/a&gt;, I'm adding an example. This flight is from JFK to AUH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This first example is on November 1st (when DST is in effect).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGsco.jpg&quot; alt=&quot;EDT example&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Departure    Arrival&#xA;EDT 12:40    EDT 01:10&#xA;UTC 16:40    UTC 05:10&#xA;GST 20:40    GST 09:10 (GST: Gulf Standard Time)&#xA;&#xA;Flight Duration: 12:30&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This is the same flight on November 2nd (when DST is not in effect).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Q19x.jpg&quot; alt=&quot;ET example&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Departure    Arrival&#xA;ET  11:40    ET  00:10&#xA;UTC 16:40    UTC 05:10&#xA;GST 20:40    GST 09:10 (GST: Gulf Standard Time)&#xA;&#xA;Flight Duration: 12:30&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Footnotes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1&lt;/em&gt;: Not all parts of a single country may observe DST. In USA (for example), most parts of Arizona &lt;a href=&quot;http://en.wikipedia.org/wiki/Daylight_saving_time_in_the_United_States#Local_DST_observance&quot; rel=&quot;nofollow noreferrer&quot;&gt;do not&lt;/a&gt; observe DST. I agree with them, DST does not &lt;a href=&quot;http://en.wikipedia.org/wiki/Daylight_saving_time#Dispute_over_benefits_and_drawbacks&quot; rel=&quot;nofollow noreferrer&quot;&gt;make any sense or provide any benefit&lt;/a&gt; in today's world.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-02-24T19:05:53.350" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9311" PostTypeId="1" AcceptedAnswerId="33965" CreationDate="2014-10-24T22:21:04.007" Score="25" ViewCount="77094" Body="&lt;p&gt;Say one wanted to buy a retired F-14, or F-5, or a BAE Hawk. Could I do it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously this would mean stripping out radars, weapons, rwr, and any other sensitive equipment, but after this, would it be possible?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some kind of procedure for this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: What is the typical way aircraft are released for sale? Is it common?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="572" LastEditDate="2015-02-24T10:51:44.253" LastActivityDate="2020-09-06T00:44:57.643" Title="Can civilians buy military aircraft?" Tags="&lt;military&gt;&lt;aircraft-ownership&gt;&lt;regulations&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9312" PostTypeId="2" ParentId="9311" CreationDate="2014-10-24T23:00:53.063" Score="16" Body="&lt;p&gt;You could, if the aircraft is available for sale somewhere, and there are no other legal compliance problems. Paul Allen has a nice collection of military aircraft at his &lt;a href=&quot;http://www.flyingheritage.com/&quot;&gt;Flying Heritage Collection&lt;/a&gt;, and there are certainly quite a few other people with both flyable and unflyable military aircraft. There are also private companies which will let you try out their planes, such as &lt;a href=&quot;http://austjetadv.com.au/&quot;&gt;Australian Jet Adventures&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a web site which tracks military planes in private ownership around the world:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.warbirdalley.com/&quot;&gt;http://www.warbirdalley.com/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3665" LastActivityDate="2014-10-24T23:00:53.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9313" PostTypeId="1" AcceptedAnswerId="9324" CreationDate="2014-10-25T03:26:56.283" Score="17" ViewCount="1482" Body="&lt;p&gt;The manifold pressure gauge of the Japanese &lt;a href=&quot;http://en.wikipedia.org/wiki/Kawasaki_Ki-61&quot; rel=&quot;noreferrer&quot;&gt;Ki-61&lt;/a&gt; has values which go from +40 to -40. I know this has to be relative to &lt;em&gt;something&lt;/em&gt; since negative pressure can't exist (you can't get more vacuum than a vacuum), but I'm not sure what it's relative to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why did the manifold pressure gauge on the Ki-61 have negative values?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lNPRl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vihXA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="65" LastEditDate="2014-10-25T18:13:30.010" LastActivityDate="2017-05-12T23:07:03.103" Title="Why did the manifold pressure gauge on the Ki-61 have negative values?" Tags="&lt;flight-instruments&gt;&lt;piston-engine&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9314" PostTypeId="2" ParentId="9311" CreationDate="2014-10-25T10:46:30.267" Score="7" Body="&lt;p&gt;It partially depends on whether the military giving them up are willing to let the technology go. In the case of the F14 every single one had their engines and any novel systems destroyed completely after retirement to keep any parts from getting to Iran, which bought F14s before the revolution deposed the Shah. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for getting one most militaries go through a middleman of some sort, which one is used depends on the country and branch. There are exceptions for this, for example the UK MOD sells things &lt;a href=&quot;http://www.mod-sales.com/direct/&quot; rel=&quot;noreferrer&quot;&gt;on-line&lt;/a&gt; although aircraft are rarely posted. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2014-10-25T18:51:23.303" LastActivityDate="2014-10-25T18:51:23.303" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9315" PostTypeId="1" AcceptedAnswerId="9316" CreationDate="2014-10-25T16:00:05.057" Score="8" ViewCount="2948" Body="&lt;p&gt;I've got a private pilot license and learned on a &lt;a href=&quot;http://en.wikipedia.org/wiki/Scheibe_Falke&quot; rel=&quot;nofollow&quot;&gt;Scheibe Falke SF25&lt;/a&gt;. For the last year however I've only been flying a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ikarus_C42&quot; rel=&quot;nofollow&quot;&gt;C42 Ultralight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find flying the UL way easier for one particular reason: it has flaps where the Falke has just airbrakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how many hundred landings on the Falke I have done, still I have never felt comfortable. The reason is the airbrake. For some reason it scares me. With the UL I set the speed, lower the flaps and if I'm too far away I can add a little power. The flaps lower the stall speed and make the plane slower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airbrakes also make the plane slower, however they &lt;strong&gt;increase&lt;/strong&gt; the stall speed. I see how (especially flight instructors) pull the air brake to the maximum and then do their approach. If I'm too far away with the Falke, I have to retract the air brakes. This affects the plane very directly, especially compared to adding a little power on the UL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How to correctly land a plane with airbrakes? Full out or just a bit? Do you leave them in one position or do you vary during approach?&lt;/li&gt;&#xA;&lt;li&gt;How much do they really affect stall speed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="133" LastEditorUserId="22726" LastEditDate="2019-02-27T23:05:22.413" LastActivityDate="2019-02-27T23:05:22.413" Title="How does flying with flaps differ from flying with airbrakes?" Tags="&lt;approach&gt;&lt;flaps&gt;&lt;airbrakes&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9316" PostTypeId="2" ParentId="9315" CreationDate="2014-10-25T20:16:30.600" Score="9" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Scheibe_Falke&quot;&gt;SF-25&lt;/a&gt; has such a low wing loading that it easily tolerates the small reduction in maximum lift which the airbrakes cause. I have done very few flights in it (I'm too tall to fit comfortably in it's cramped cockpit), but from what I remember the airbrakes are not very big, having little effect on minimum speed. My experience, however, is with the SF-25 B, and you linked to the SF-25 C, so I have to assume that my experience is not fully relevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have more experience with real gliders and composite motorgliders, and here my experience is: Start your approach, stabilize the right approach speed, set the airbrakes such that your glide path looks right and do not play around with them too much. Set your approach such that you need medium airbrake extension, so you have margin for corrections in both directions. Normally, I come in a little high so I am not caught by windshear, and when I am sure I will reach the intended touchdown point, I extend the airbrakes fully to land with the shortest distance possible. However, when touching down, make sure you do not fully extend the airbrakes: This gives you more time for stopping the descent. Especially in gliders with very effective flaps and airbrakes (&lt;a href=&quot;http://en.wikipedia.org/wiki/Schleicher_ASW_20&quot;&gt;ASW-20 C&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Schleicher_ASH_25&quot;&gt;ASH-25&lt;/a&gt;) I &lt;strong&gt;never&lt;/strong&gt; made a good landing with fully extended airbrakes. Reduce them to half extension at the most when touching down!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the ASW gliders the airbrakes are linked to the very effective wheel brake, and touching down with fully deployed airbrakes means that the wheel is braked at touchdown. This is another reason to reduce airbrake extension when touching down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In high-performance gliders it is easy to float too long, so it is very important to control your approach speed and to continue the descent all the way down to the touchdown point. Don't pull too early! The SF-25 will not float as much, but with its low wing it shows a pronounced ground effect, and exercising strict discipline when landing helps a lot to make the landing better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find a number for the stall speed change due to airbrakes in the &lt;a href=&quot;http://www.flugplatz-niederstetten.de/SF25h.pdf&quot;&gt;SF-25 manual&lt;/a&gt;, but I would guess it is at most a few km/h. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-26T09:49:01.390" LastActivityDate="2014-10-26T09:49:01.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9321" PostTypeId="2" ParentId="9243" CreationDate="2014-10-26T03:40:16.177" Score="2" Body="&lt;p&gt;It's been done, but it was a major engineering feat just to do it with a four-person crew capsule.  Ejecting sections of the passenger compartment of a commercial airliner would be even more difficult.  As others have noted, it would significantly increase the cost and complexity of the aircraft and decrease its payload for very little improvement in safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://youtu.be/n0TVr0_m34s?t=17s&quot; rel=&quot;nofollow&quot;&gt;Here is footage of the B-1b Lancer crew capsule.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4051" LastEditorUserId="2171" LastEditDate="2014-10-26T04:14:58.380" LastActivityDate="2014-10-26T04:14:58.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9322" PostTypeId="2" ParentId="9315" CreationDate="2014-10-26T05:22:16.393" Score="3" Body="&lt;p&gt;I would not recommend flying an approach to land with maximum airbrakes.  Instead, what I was taught to do in a glider (or a motor-glider without the engine running) is to plan and fly the approach with about 1/2 airbrake extension.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows you to use the airbrake handle much like you would use the throttle in an aircraft with a running engine:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Getting a little low or slow - Retract the airbrakes as far as needed to return to your normal approach angle.&lt;/li&gt;&#xA;&lt;li&gt;Getting a little high or fast - Extend the airbrakes as far as needed to return to your normal approach angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You then touch down with whatever airbrake extension was required, and then fully extend them afterwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps are unrelated to airbrakes, and you can have gliders with or without either of them.  Some gliders have both!  The flaps allow you to slow further, which reduces your ground roll and also increases drag.  This is important in high performance gliders because it can be very hard to actually make them go down without gaining speed when you want to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as how much they affect the stall speed, this is very much dependant upon the specific aircraft and the design of the airbrakes/wing.  The POH should describe any special procedures (such as flying your approach speed + 10 with full airbrake extension) if they are needed.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-10-26T05:22:16.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9323" PostTypeId="1" CreationDate="2014-10-26T06:22:41.253" Score="7" ViewCount="1328" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?idno=14;region=DIV1;type=boolean;c=ecfr;cc=ecfr;q1=oxygen;rgn1=Section;op2=and;rgn2=Section;op3=and;rgn3=Section;rgn=div8;view=text;node=14%3A2.0.1.3.10.3.7.6&quot; rel=&quot;nofollow&quot;&gt;FAR 91.211&lt;/a&gt; tells us &lt;strong&gt;&lt;em&gt;when&lt;/em&gt;&lt;/strong&gt; supplemental oxygen is required, but it's not very specific as to &lt;strong&gt;&lt;em&gt;how&lt;/em&gt;&lt;/strong&gt; that oxygen is to be provided. &lt;a href=&quot;http://www.gpo.gov/fdsys/granule/CFR-2011-title14-vol1/CFR-2011-title14-vol1-sec23-1447&quot; rel=&quot;nofollow&quot;&gt;FAR 23.1447&lt;/a&gt; gives some information about &lt;em&gt;installed&lt;/em&gt; systems, but I can't find much on FAA requirements if you're using a &lt;em&gt;portable&lt;/em&gt; system (cylinder, regulator, and cannula/mask like &lt;a href=&quot;http://www.mhoxygen.com&quot; rel=&quot;nofollow&quot;&gt;a Mountain High system&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there specific requirements/recommendations regarding portable oxygen equipment for Part 91 General Aviation, or can you just pick up a a medical or welding tank, stick a regulator on it, and pass out masks to your passengers?&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-03-16T18:03:34.257" LastActivityDate="2015-09-05T15:30:43.673" Title="What equipment qualifies as FAA-acceptable for providing &quot;Supplemental Oxygen&quot;?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;oxygen&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9324" PostTypeId="2" ParentId="9313" CreationDate="2014-10-26T09:41:37.853" Score="8" Body="&lt;p&gt;Disclaimer: I do not know if my answer is correct, but I think it is plausible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Ki-61 engine was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Kawasaki_Ha40&quot; rel=&quot;noreferrer&quot;&gt;Kawasaki Ha-40&lt;/a&gt;, a Japanese version of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Daimler-Benz_DB_601&quot; rel=&quot;noreferrer&quot;&gt;Daimler-Benz DB 601 Aa&lt;/a&gt; turbocharged inverted-V inline engine, so I would assume that the engine instrumentation was inspired by what was used in Germany at that time. Manifold pressure was measured in ata (Atmosphäre absolut, close to 1 bar), which is multiples of the standard atmospheric pressure. The picture below shows the manifold pressure gauge of the Me-109 G, which used the DB 605 A. This was derived from the DB 601, and the manifold pressure gauge has a range from 0.6 ata to 1.8 ata.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lojmN.jpg&quot; alt=&quot;Me-109 cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.deutscheluftwaffe.de/archiv/Dokumente/ABC/b/Me%20109e/Bf109%20e%20Handbuch.pdf&quot; rel=&quot;noreferrer&quot;&gt;DB 601 A had a maximum manifold pressure at sea level of 1.35 ata&lt;/a&gt;. This lets me assume that the Ha-40 was also turbocharged to 1.35 ata, which is 1.368 bar. The critical altitude was probably only 3700 m. The regular DB 601 A had a critical altitude of 4500 m, which was reduced in the DB 601 Aa export version to 3700 m. I could not find a direct reference for the critical altitude of the Ha-40.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the 11,600 m service ceiling of the Ki-61, the atmospheric pressure is 206.6 mbar. Now we need to factor in the ram pressure gain of approx. 20% at 300 kts TAS, and with the 2.14 compression ratio needed for a critical altitude of 3700 m, this would translate to a manifold pressure of 530 mbar or 0.522 ata. If the Kawasaki engineers raised that to the 2.37 compression ratio of the original DB 601 A, the manifold pressure at 11,600 m could even had been 578 mbar or 0.570 ata.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most plausible explanation for the numbers on the manifold pressure gauge now would be percentage over rsp. below 1 ata, the static pressure at sea level. Since it is more important to not overstress the engine at low level, the +40 upper limit fits well to the maximum 1.35 ata setting. This fits also well with the static value of 0, meaning 1 atmosphere. At high altitude the compressor would run at maximum setting anyway, and the scale here is for informing the pilot about available power, and would not cover the lowest values close to maximum altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find a performance chart for the Ha-40 or the DB 601 A, and the nearest Google dug out for me is the performance chart of the DB 601 E below. Please note that this engine had more performance (2700 RPM and 1.42 ata manifold pressure for takeoff; the DB 601 A used 2400 RPM and 1.35 ata) and a higher critical altitude of 4800 m:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QbmGY.jpg&quot; alt=&quot;DB 601 E performance&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-10-26T09:41:37.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9325" PostTypeId="1" CreationDate="2014-10-26T10:09:45.840" Score="5" ViewCount="4520" Body="&lt;p&gt;If the EPU (Emergency Power Unit) and batteries plus engines fail on a modern fighter aircraft, basically they will fall out of the sky, there is no dead stick landing - is this correct?&lt;/p&gt;&#xA;" OwnerUserId="4053" LastEditorUserId="1696" LastEditDate="2018-04-27T14:18:25.020" LastActivityDate="2018-04-27T14:18:25.020" Title="If the EPU (Emergency Power Unit) on a modern fighter jet fails, will the aircraft drop out of the sky?" Tags="&lt;safety&gt;&lt;fighter&gt;&lt;accidents&gt;&lt;engine-failure&gt;&lt;apu-failure&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9327" PostTypeId="1" AcceptedAnswerId="9331" CreationDate="2014-10-26T13:30:09.517" Score="3" ViewCount="282" Body="&lt;p&gt;For example, the Rotax 912ULS engine has a 2.4:1 reduction. Does this mean that the Time Between Overhaul (TBO) will be reached 2.4x faster than in a direct drive engine or is tach time reduced by 2.4:1 as well?&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="3495" LastEditDate="2014-10-26T14:17:46.790" LastActivityDate="2014-10-26T17:02:08.797" Title="Do reduction drives increase tach time quicker than direct drive engines?" Tags="&lt;piston-engine&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9329" PostTypeId="1" AcceptedAnswerId="9330" CreationDate="2014-10-26T16:18:28.187" Score="37" ViewCount="14524" Body="&lt;p&gt;I was watching a documentary on youtube and the pilots always say something that sounds like &quot;B1E&quot; when they have enough speed to take off. What exactly are they saying, and why do they say it?&lt;/p&gt;&#xA;" OwnerUserId="4057" LastEditorUserId="97" LastEditDate="2014-10-26T17:31:18.333" LastActivityDate="2015-08-19T21:40:09.763" Title="What do jet pilots say during the takeoff as they are speeding down the runway?" Tags="&lt;takeoff&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9330" PostTypeId="2" ParentId="9329" CreationDate="2014-10-26T16:22:57.493" Score="64" Body="&lt;p&gt;What you are hearing is &amp;quot;V-One&amp;quot;, written as V&lt;sub&gt;1&lt;/sub&gt;.&lt;/p&gt;&#xA;&lt;p&gt;It actually is said when they can no longer safely abort the takeoff with the remaining runway, but they still are not quite ready to takeoff.&lt;/p&gt;&#xA;&lt;p&gt;As they get a little faster, there should then be a second callout of &amp;quot;Rotate&amp;quot; when they have achieved the required takeoff speed, and that is when they actually takeoff.&lt;/p&gt;&#xA;&lt;p&gt;To answer the &amp;quot;why&amp;quot; part, it is said by the pilot who isn't actually flying the airplane since he has more time to monitor the speed and can say it at exactly the right time.  It alerts the other pilot that it is no longer safe to abort the takeoff and that pretty much no matter what happens now, they should continue and come back to land if needed.&lt;/p&gt;&#xA;&lt;h3&gt;Edit:&lt;/h3&gt;&#xA;&lt;p&gt;In my answer above, I simplified somewhat by only mentioning the available runway.  There are other factors that can come into play even with a runway that is longer than needed.  One example would be the speed after which the brakes can no longer stop the airplane because they would over-heat and become ineffective.  This is known as the brake energy limit, and it is not safe to abort above this speed, even if you have &amp;quot;plenty&amp;quot; of runway.&lt;/p&gt;&#xA;&lt;p&gt;V&lt;sub&gt;1&lt;/sub&gt; must be calculated or looked up prior to every takeoff, along with the other performance numbers.  They vary based on the weight of the aircraft, the configuration of the aircraft, the altitude of the runway, and the weather (outside temperature, wind, etc.).  Sometimes this is done via a computer and sometimes manually via lookup tables or even graphs.&lt;/p&gt;&#xA;&lt;p&gt;For an example of the graphs, and more information about how temperature and altitude affect takeoff performance, see my previous answer here:&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/1533/69&quot; title=&quot;Takeoff Performance&quot;&gt;Does temperature affect takeoff performance?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;There are also times when a pilot may increase or decrease V&lt;sub&gt;1&lt;/sub&gt; intentionally, even when it is not required.  For instance, if there is wet ice on the runway it may not be safe to abort even at a very low speed, so you would be forced to continue no matter what (note that I'm NOT saying that this is a good idea). Using a lower power setting to extend engine life is another example, and you can read about it in my question here:&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/472/69&quot;&gt;Why would an airplane pilot choose to intentionally use more runway than required for a takeoff?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;For way more information than you probably care about takeoff performance, see my other answer here:&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/3567/69&quot;&gt;Minimum Runway Length and V&lt;sub&gt;1&lt;/sub&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In closing, aircraft performance planning is a rather complicated subject and it is only one of many subjects that we must master in order to safely fly an airplane.  This only just scratches the surface of it, and there is a lot more that must be considered (such as &amp;quot;hey, will we be able to out-climb that tree off the end of the runway?&amp;quot;).&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-19T17:40:33.550" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9331" PostTypeId="2" ParentId="9327" CreationDate="2014-10-26T17:02:08.797" Score="5" Body="&lt;p&gt;The relationship between tach time and RPM &lt;a href=&quot;https://aviation.stackexchange.com/questions/7930/where-to-find-tach-hour-and-clock-hour-equivalence-rpm&quot;&gt;varies based on the engine&lt;/a&gt;. As mentioned in the linked answer, it is difficult to find this relationship based on engine specifications, but if you find a tachometer certified for the engine it will have the correct ratio built in.&lt;/p&gt;&#xA;&lt;p&gt;If the 912ULS needed TBO based on tach times, the tachometer would likely count tach time at 1:1 somewhere below 5500 RPM, since that is the &lt;a href=&quot;http://www.flyrotax.com/portaldata/5/dokus/d05649.pdf&quot; rel=&quot;noreferrer&quot;&gt;maximum continuous speed&lt;/a&gt; for this engine. However, Rotax actually uses &lt;a href=&quot;https://aviation.stackexchange.com/q/7430/136&quot;&gt;Hobbs time&lt;/a&gt; to determine when an engine needs a TBO, and specifically notes that a &amp;quot;mechanical hour meter&amp;quot; may give different times. Therefore, the TBO of 2000 hours is 2000 hours of real-world time.&lt;/p&gt;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.flyrotax.com/portaldata/5/dokus/d05562.pdf&quot; rel=&quot;noreferrer&quot;&gt;912 Series Maintenance Manual&lt;/a&gt;: (p. 3)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;All of the maintenance intervals, such as the 100 hr. inspection and the engine TBO, relate to the number of operating hours of the engine.&lt;/p&gt;&#xA;&lt;p&gt;The operating hours are defined as follows in order to prevent misunderstandings and to ensure safety:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;All time during which the engine is running is counted towards the total number of operating hours.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The time is counted irrespective of the load factor of the engine, such as idling or take-off power.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;NOTES: A mechanical hour meter is directly coupled to the engine speed, the readings may deviate considerably from those given by electronic remitters (e.g. TCU, FlyDat). Maintenance and overhaul intervals are always dictated by the readings of the electronic hour meter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-26T17:02:08.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9332" PostTypeId="2" ParentId="9323" CreationDate="2014-10-26T18:24:08.160" Score="5" Body="&lt;p&gt;An even more important question than &lt;em&gt;how&lt;/em&gt; is &lt;em&gt;how much&lt;/em&gt; oxygen to take, but there's no specific FAA guidance or regulation on either point. Different aircraft can carry different equipment, and people have different requirements depending on their age, lungs, blood chemistry, whether they smoke, day vs. night etc. The FAA's &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;source=web&amp;amp;rct=j&amp;amp;ei=Lg5NVIu2B4_iaNf2gsgL&amp;amp;url=http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Oxygen_Equipment.pdf&amp;amp;ved=0CCAQFjAB&amp;amp;usg=AFQjCNG04_uKXL-TnoOpuV1C1BGvHNkp3Q&amp;amp;sig2=0epQsTQNLDTljJSyiyyeBQ&quot;&gt;guide&lt;/a&gt; on oxygen equipment for GA use is extremely limited and although it describes a range of equipment types it doesn't mention any specific requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, the 'usual' approach seems to be to use a &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Pulse_oximetry&quot;&gt;pulse oximeter&lt;/a&gt; to measure your &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Oxygenation_(medical)#Measurements&quot;&gt;oxygen saturation&lt;/a&gt; and if it's too low then go on oxygen immediately, regardless of altitude or other considerations. The moderator of AOPA's medical forum is an &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Aviation_Medical_Examiner&quot;&gt;AME&lt;/a&gt; and he recommends oxygen use any time your saturation level drops below 90%, which is apparently also the required level in hospitals for a patient to make an &quot;informed&quot; - i.e. clearheaded - decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But returning to the question of equipment, there aren't any regulations on this at all, so provided that the equipment is safe to use in the aircraft (including not obstructing exits and so on) and not illegal under any other law that might apply (carriage of dangerous goods or whatever) then you can go for it. But the usual 'always act as if you'll have to justify your decisions to the FAA tomorrow' advice applies here, IMO, and personally I would always go with an aviation-specific setup if I needed one.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-26T18:24:08.160" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9333" PostTypeId="1" AcceptedAnswerId="9335" CreationDate="2014-10-27T02:00:32.937" Score="12" ViewCount="30901" Body="&lt;p&gt;I haven't been able to understand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If propeller control controls the pitch of the blades in a constant speed engine, what do the throttle control do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen (in some normal operation manuals for some planes) that you have a Torque limit and control the Torque with the throttle control, and the RPM with the Propeller Control, but, if the propeller is spinning always at the same speed and the blades are positioned at the same pitch how can the throttle reduce or increase thrust? &lt;/p&gt;&#xA;" OwnerUserId="4060" LastEditorUserId="97" LastEditDate="2014-10-27T21:53:25.087" LastActivityDate="2019-04-27T09:37:52.970" Title="How do Throttle control and Propeller control work together?" Tags="&lt;propeller&gt;&lt;throttle&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9334" PostTypeId="2" ParentId="9333" CreationDate="2014-10-27T02:13:36.133" Score="1" Body="&lt;p&gt;The throttle controls the engine power. In most engines (car, lawnmower etc.) this also controls the RPM. The prop control adjusts the pitch of the prop blades and thus the load on the engine, so the RPM stays the same (hence: &quot;constant speed&quot;) but it will fall off speed if there isn't enough power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it's a &quot;constant speed PROP&quot;, not a &quot;constant speed engine&quot;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-10-27T02:13:36.133" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9335" PostTypeId="2" ParentId="9333" CreationDate="2014-10-27T05:27:56.633" Score="14" Body="&lt;p&gt;In a constant speed prop, the prop control lever basically changes the speed of the prop (it is not always running at the same speed as you indicate in your question, but rather once the speed is &lt;strong&gt;changed&lt;/strong&gt; by the prop control lever, the governor keeps it at that speed). If power (or airspeed) is changed, the blade angle will automatically change in order to keep the prop turning at the same speed (within the limits that it is designed for).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since adding power would normally increase the speed of the prop, the governor automatically changes the blade angle in order to keep it at the same speed.  The same is true when power is reduced or airspeed is changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust is changed by engine power because, even though the prop is turning at the same speed, the angle of attack of the prop has been changed, which changes the amount of thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more general information about how a constant speed prop works, see this question and answers:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/1381/69&quot;&gt;How does a Constant Speed Propeller Work?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-10-27T05:27:56.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9336" PostTypeId="2" ParentId="9333" CreationDate="2014-10-27T06:59:08.893" Score="4" Body="&lt;p&gt;First and foremost, speed of the propeller does not govern the thrust it is producing. It only limits it from above. The faster the propeller turns the more thrust it can provide, but it can produce less depending on power the engine supplies. With engine at idle, the propeller produces drag only and at higher rpm it produces more drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next engine speed (and aircraft have fixed gear, so engine speed is proportional to propeller speed) does not govern the power it provides either, but also only limits it from above. The engine can only produce this amount of power per revolution, but if you restrict the fuel or fuel-air mixture flow into the engine, it will produce less. Consider coasting at high speed in a car with gear on. The engine turns at high rpm, because it is connected to the turning wheels, but with accelerator released it does not produce any power and the car is slowing down. The same happens in aircraft. At idle the propeller windmills by oncoming air and cranks the engine, but because that produces no power, the net effect is decelerating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The throttle restricts flow of fuel-air mixture in the engine and is therefore the main control of engine power. &quot;Throttle&quot; really means the restriction flap in carburettor, so in diesel and turbine engines where fuel flow is controlled instead the lever is called a &quot;power&quot; or &quot;thrust&quot; lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why don't you always run the propeller at the maximum rpm? Higher rpm increases wear on the engine. So usually high rpm is used for take-off where maximum power is needed, then rpm is reduced to recommended cruise value to reduce wear of the engine and for landing high rpm is selected again to increase drag of windmilling to slow down and to have full power available in case of go around.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-10-27T06:59:08.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9338" PostTypeId="2" ParentId="3306" CreationDate="2014-10-27T10:19:07.767" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why are push-propellers so rare&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Other answers have covered this.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;yet they are still around?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A front mounted propeller limits the field of view of the pilot or payload. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a surveillance drone or UAV. There's no pilot whose view would be obscured but there is almost certainly a great advantage for the radar, optical and other forward-looking systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surveillance missions can benefit from a relatively slow-moving, low-altitude platform. This favours the use of propellors rather than jets and the pusher arrangement can be beneficial as noted above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZDcwg.jpg&quot; alt=&quot;Photo of MQ-9 Reaper drone in flight&quot;&gt;  MQ-9 Reaper&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7ft6c.jpg&quot; alt=&quot;enter image description here&quot;&gt; Elbit Hermes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aY3NF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;Sagem Sperwer&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-27T10:34:23.040" LastActivityDate="2014-10-27T10:34:23.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9339" PostTypeId="1" AcceptedAnswerId="9345" CreationDate="2014-10-27T11:03:37.653" Score="7" ViewCount="19532" Body="&lt;p&gt;What exactly is the difference between a B777-31H and B777-31H(ER)? Is ER the latest version of 777-31H? &lt;/p&gt;&#xA;" OwnerUserId="4064" LastEditorUserId="4064" LastEditDate="2014-10-27T11:42:00.207" LastActivityDate="2017-01-26T06:41:33.040" Title="What is the difference between Boeing 777-31H and Boeing 777-31H(ER)?" Tags="&lt;boeing&gt;&lt;boeing-777&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9340" PostTypeId="1" AcceptedAnswerId="9356" CreationDate="2014-10-27T11:29:43.263" Score="6" ViewCount="7808" Body="&lt;p&gt;I'm wondering how many 747-200's are still in service?&#xA;I know for sure &lt;a href=&quot;https://www.youtube.com/watch?v=BDaagO2iYdM&quot;&gt;Rolls Royce is using one for testing purposes&lt;/a&gt;.&#xA;&lt;a href=&quot;https://www.youtube.com/watch?v=doElXk4faRQ&quot;&gt;And the one from the US Forces.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are there any civilian operated ones left? &lt;/li&gt;&#xA;&lt;li&gt;Does somebody have photos?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="97" LastEditDate="2014-10-27T21:52:07.643" LastActivityDate="2014-10-28T16:18:11.910" Title="How many 747-200 are still in service?" Tags="&lt;aviation-history&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9341" PostTypeId="2" ParentId="9340" CreationDate="2014-10-27T11:45:16.140" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How many 747-200 are still in Service?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you search &lt;a href=&quot;http://www.airfleets.net/listing/b747-1.htm&quot; rel=&quot;noreferrer&quot;&gt;Airfleets.net&lt;/a&gt; and, for all pages, add up the aircraft marked as active, you will get an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YAGry.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Are there any Civilian Operated ones left?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you mean non-military, the above method should tell you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you mean non-airline, I don't know how to find out easily. RR's &lt;a href=&quot;https://www.google.com/search?q=N-787RR+747+image&amp;amp;es_sm=122&amp;amp;tbm=isch&quot; rel=&quot;noreferrer&quot;&gt;N-787RR&lt;/a&gt; was &lt;a href=&quot;http://www.airfleets.net/ficheapp/plane-b747-21966.htm&quot; rel=&quot;noreferrer&quot;&gt;hard to find&lt;/a&gt; at Airfleets.net.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Does somebody have Photos?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Almost certainly yes, I'd just Google the registration number. e.g. &lt;a href=&quot;https://www.google.com/search?q=ep-shb+747&amp;amp;source=lnms&amp;amp;tbm=isch&quot; rel=&quot;noreferrer&quot;&gt;EP-SHB&lt;/a&gt;. They'll mostly be copyright protected of course.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-27T12:00:54.087" LastActivityDate="2014-10-27T12:00:54.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9342" PostTypeId="2" ParentId="199" CreationDate="2014-10-27T13:42:21.593" Score="6" Body="&lt;p&gt;I did a crossing in a Beech Bonanza in mid-july; even during that month I picked up ice. I wouldn't cross VFR unless you had a lot of time sitting around iceland waiting for a large high pressure system to stumble your way. As an example faroe was clear when I arrived and the control folks said the sky hadn't been clear in 20,days; so I got a nice clear day of sight seeing. Bergen was socked in IFR with ice, so I was delayed even having IMC capable plane and CMEL-IR... The weather systems are smaller up north, and they tend to linger it seems.&lt;/p&gt;&#xA;" OwnerUserId="4069" LastActivityDate="2014-10-27T13:42:21.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9343" PostTypeId="1" CreationDate="2014-10-27T13:48:13.113" Score="0" ViewCount="665" Body="&lt;p&gt;What is engine-out taxi out time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) The time between the first movement of the aircraft &lt;strong&gt;under its own power&lt;/strong&gt; and the start of the last engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) The time between the first movement of the aircraft regardless if it's being pushed back &lt;strong&gt;without&lt;/strong&gt; any engines running and the start of the last engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And one additional question - how would you define the the start of the last engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) The moment the fuel valve is opened&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) The first moment the engine is running (stable N1, fuel flow, oil pressure and temperature, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) Something else&lt;/p&gt;&#xA;" OwnerUserId="3708" LastEditorUserId="7532" LastEditDate="2016-11-12T07:42:18.760" LastActivityDate="2016-11-12T07:42:18.760" Title="What is engine-out taxi out time?" Tags="&lt;taxiing&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9344" PostTypeId="2" ParentId="9343" CreationDate="2014-10-27T13:52:25.937" Score="2" Body="&lt;p&gt;It's the time taxiing without engines on, for example when under tow or during push back. As opposed to when you're taxiing under the aircraft's own power&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second is potentially subjective, but I'd personally count it as the moment the engine is actually running, post-start up procedure: that's the moment when I could use the engine as an actual engine with useful power.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2016-11-11T15:04:49.800" LastActivityDate="2016-11-11T15:04:49.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9345" PostTypeId="2" ParentId="9339" CreationDate="2014-10-27T14:39:00.750" Score="15" Body="&lt;p&gt;The 777-31H is a standard Boeing 777-300 manufactured for Emirates (customer code 1H).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 777-31H(ER) is a Boeing 777-300ER (Extended Range) again for Emirates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to the standard 777-300, the 777-300ER has:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A longer range due to the extra fuel it can carry (145538 kg compared to 135880 kg for the -300 baseline)&lt;/li&gt;&#xA;&lt;li&gt;A higher Operating Empty Weight (167829 kg compared to 159570 kg for the -300 baseline)&lt;/li&gt;&#xA;&lt;li&gt;A higher Maximum Take-Off Weight (351535 kg compared to 299370 kg for the -300 baseline)&lt;/li&gt;&#xA;&lt;li&gt;A higher maximum structural payload weight (69853 kg compared to 64960 kg for the -300 baseline)&lt;/li&gt;&#xA;&lt;li&gt;A wider wingspan (64.80 compared to 60.93 m)&lt;/li&gt;&#xA;&lt;li&gt;A different engine delivering more thrust&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The Boeing 777-300ER is always equipped with General Electric GE90-115BL1 engines, while the baseline -300 can be ordered with four different engine models from General Electric, Pratt&amp;amp; Whitney or Rolls Royce. The Emirates Boeing 777-300 aircraft have the Rolls Royce RR Trent 892 engines installed. They deliver 415 kN of thrust, almost 100 kN less than the GE90-115BL1 engines.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-10-27T14:39:00.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9346" PostTypeId="1" AcceptedAnswerId="9347" CreationDate="2014-10-27T14:41:06.393" Score="18" ViewCount="2092" Body="&lt;p&gt;I found this topic on an external site, it's about a Boeing 737-4 damaged during engine run up at Sialkot international Airport (Pakistan): &lt;a href=&quot;https://www.airliners.net/forum/viewtopic.php?t=573541&quot; rel=&quot;noreferrer&quot;&gt;NL B734 Damaged During Engine Run Up&lt;/a&gt; (&lt;a href=&quot;https://www.facebook.com/AME.World/posts/10152248845712798&quot; rel=&quot;noreferrer&quot;&gt;photos&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;In the comments/discussion, people say that there is similar apron paving made of blocks at other major airports.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Are there any photos or verification of lose-block apron?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One comment says that London Heathrow has some, does somebody have any verification or Link?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Block paving is very common at airports. All over Heathrow and Gatwick. It works fine when its built correctly but if it's not maintained well then that happens.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-15T14:25:16.793" Title="How common are aprons made of bricks?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9347" PostTypeId="2" ParentId="9346" CreationDate="2014-10-27T14:59:49.490" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Hong Kong International Airport represents the largest single airfield installation of interlocking concrete pavements. Since most of the airport is on reclaimed land, anticipated settlement required that flexible asphalt pavement be used instead of rigid concrete for runways. Concrete pavers also provide a more fuel-resistant surface than asphalt.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.paveshare.org/library/category/paver&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/W4fFS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;See also&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/33550/spec_35.pdf&quot; rel=&quot;noreferrer&quot;&gt;Concrete Block Paving &#xA;for Airfields&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.icpi.org/sites/default/files/techpapers/530.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airfield pavement design with concrete pavers&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ascelibrary.org/doi/abs/10.1061/40579%28271%2921&quot; rel=&quot;noreferrer&quot;&gt;Evolution of Interlocking Concrete Pavements for Airfields&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.sept.org/techpapers/54.pdf&quot; rel=&quot;noreferrer&quot;&gt;THE USE OF INTERLOCKING CONCRETE BLOCKS ON AN AIRCRAFT PAVEMENT IN AUSTRALIA&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-27T15:14:59.370" LastActivityDate="2014-10-27T15:14:59.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9349" PostTypeId="1" AcceptedAnswerId="9351" CreationDate="2014-10-27T15:20:03.020" Score="11" ViewCount="1776" Body="&lt;p&gt;A lot of people reading this probably saw Top Gun and remember Maverick performing a fly-by over the deck of the USS Enterprise (in spite of being explicitly ordered not to do so), or saw air shows where aerobatic pilots do all kinds of cool maneuvers for the entertainment of the people on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I didn't know was possible is that a commercial aircraft with passengers on board would be allowed to perform such maneuver over an active civilian airport (&lt;a href=&quot;https://www.youtube.com/watch?v=gFAarLdTD38&quot;&gt;you can find the video here&lt;/a&gt;). The video shows the last approach and landing of a commercial pilot before retirement, in which he's allowed to perform a fly-by over the runway of &lt;a href=&quot;https://maps.google.com.ar/maps?ll=-34.559764,-58.413491&amp;amp;spn=0.021488,0.042272&amp;amp;t=h&amp;amp;z=15&quot;&gt;Jorge Newbery airport in Buenos Aires, Argentina&lt;/a&gt;. Throughout the video you can hear other pilots over the radio saluting the pilot who is about to retire, and near the end you can see the passengers applaud and airport and airline personnel on the taxi runway welcoming the aircraft. It's a pretty emotional video even for someone like me who's not related in any way to the aviation community, you should see it if you can spare a couple of minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I know that there are certain traditions involved in the last flight of a pilot before retirement but I didn't know that a flyby was one of them. In order obey the rules of this site, the main question I'm asking here is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What would be the right circumstances where a stunt like this would be allowed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But I would also like to know if this kind of maneuver has ever been performed on similar circumstances over airports with more traffic or using a bigger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4070" LastEditorUserId="97" LastEditDate="2015-04-26T21:07:45.663" LastActivityDate="2015-04-26T21:07:45.663" Title="When do conditions permit doing a controlled fly-by over the runway of a commercial airport?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;aerobatics&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9350" PostTypeId="1" AcceptedAnswerId="9352" CreationDate="2014-10-27T15:43:52.110" Score="5" ViewCount="5328" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9346/apron-made-of-bricks#9346&quot;&gt;I'm referring to this other Question.&lt;/a&gt;&#xA;I want to know more about the B737 and the distance between the engine and the tarmac.&#xA;There are several &lt;a href=&quot;http://www.aaib.gov.uk/cms_resources.cfm?file=/Boeing%20737-436,%20G-DOCT%2006-07.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Incidents&lt;/a&gt; reported, on 737 damaging the tarmac.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the distance on a B737 engine really that little comparing to&#xA;other Aircrafts (for example A320)?&lt;/li&gt;&#xA;&lt;li&gt;Is this a design fault? Also have a look at the &lt;a href=&quot;http://www.aaib.gov.uk/cms_resources.cfm?file=/Boeing%20737-436,%20G-DOCT%2006-07.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Jet-blast pressure study&quot; page 13-14&lt;/a&gt;.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/FkCPS.png&quot; alt=&quot;Fig9:Jet-blast pressure study&quot;&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-07-28T14:57:29.987" Title="Is the ground clearance of the B737 engine low compared to similar aircraft?" Tags="&lt;boeing&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9351" PostTypeId="2" ParentId="9349" CreationDate="2014-10-27T16:11:33.160" Score="17" Body="&lt;p&gt;Essentially a flyby over the runway is nothing more than a planned and prepared go-around from a low altitude. If you say it is a stunt then it probably is not allowed under most legislations. And because of noise regulations airports aren't too happy with the manoeuvre either.&lt;/p&gt;&#xA;&lt;p&gt;However, nobody will stop you from going around if you &amp;quot;forget&amp;quot; to put your gear down.&lt;/p&gt;&#xA;&lt;p&gt;I have been in the cockpit on several flybys at several airports, all of them were dressed like a missed approach / go-around along the following lines:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot&lt;/strong&gt; &amp;gt; &amp;quot;Tower, &lt;em&gt;Hotshot01&lt;/em&gt;, requesting permission for a flyby over runway XX&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower&lt;/strong&gt; &amp;gt; Negative &lt;em&gt;Hotshot01&lt;/em&gt;, you know we can't allow that any longer due to noise restrictions. I can't prevent you from making a go around though! Cleared to land RWY XX.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot&lt;/strong&gt; &amp;gt; Hmm... ok, cleared to land, &lt;em&gt;Hotshot01&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&amp;lt;Hotshot 01 approaches the threshold and applies full power&amp;gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot&lt;/strong&gt; &amp;gt; &lt;em&gt;Hotshot01&lt;/em&gt;, going around.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Tower&lt;/strong&gt; &amp;gt; You owe me a beer now! .. &amp;lt;&lt;em&gt;vectors back to final approach / final destination&lt;/em&gt;&amp;gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-27T18:47:57.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9352" PostTypeId="2" ParentId="9350" CreationDate="2014-10-27T16:21:16.280" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is the distance on a B737 engine really that little comparing to other Aircrafts (for example A320)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The actual distance depends on the engine installed and the weight and balance of the airplane at the time. But there isn't a huge difference between the two planes. Comparing the figures, the current A320 is about 10 cm higher than the current 737 NG. The A320neo and the 737 MAX will be pretty close, with the MAX potentially getting 5 cm lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737MAXbrochure.pdf&quot;&gt;737 (MAX)&lt;/a&gt;: 43-58 cm (1.42-1.92 ft)&lt;br&gt;&#xA;&lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot;&gt;737 (NG)&lt;/a&gt;: 46-64 cm (1.5-2.08 ft)&lt;br&gt;&#xA;737 (CL): 46-53 cm (1.5-1.75 ft)&lt;br&gt;&#xA;737 (100/200): 51-58 cm (1.67-1.92 ft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A320_May2014.pdf&quot;&gt;A320neo&lt;/a&gt;: 46-56 cm (1.84 ft)&lt;br&gt;&#xA;A320: 57-85 cm (2.2-2.79 ft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those reports also show exhaust velocity profiles at takeoff thrust, but differences in the diagrams make it hard to compare. The IAE engines look to have much lower velocities than the CFM engines on either plane.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this a design fault? Also have a look at the &quot;Jet-blast pressure study&quot; page 13-14.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It depends how you look at it. In the linked report, there are several recommendations for both blast pads and the operator's procedures, but nothing regarding the design of the aircraft. So rather than telling the designers to mount their engines higher above the ground, they are making sure that facilities and procedures are designed to prevent things like this from happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as being a &quot;fault&quot; unique to the 737, the study mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...an accident very similar to that of G-DOCT, which involved an Airbus A320...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's not the only airplane that can cause problems. And the newest versions of both types will have similar and smaller distances, they probably decided that there is no facilities-related reason important enough to choose differently.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-10-27T16:21:16.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9353" PostTypeId="1" CreationDate="2014-10-27T16:56:31.657" Score="7" ViewCount="1306" Body="&lt;p&gt;Flying has been a dream for me since I was a little boy. My absolute dream career was to be a fighter pilot in the RAF. It's obviously a very hard career to get into, however I fell even before the first hurdle when I found out that I'm colour blind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finding out I was colour blind actually closed a lot of potentially enjoyable careers. Police, Armed Forces, Electrical all reject colour blind people. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd love to be able to fly, freely in a light aircraft - something like a glider or mosquito helicopter, but I just can't figure out where I need to start. Also, I'm not sure if it's financially viable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone give me a breakdown of costs and commitments needed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I'm assuming that being colour blind doesn't automatically mean I'm not able to fly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I'm in the UK&lt;/p&gt;&#xA;" OwnerUserId="4073" LastEditorUserId="97" LastEditDate="2015-04-26T21:01:04.870" LastActivityDate="2015-10-24T22:31:50.663" Title="How much does it cost to learn to fly in the UK, and what restrictions are there?" Tags="&lt;flight-training&gt;&lt;cost&gt;&lt;uk&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9354" PostTypeId="2" ParentId="9353" CreationDate="2014-10-27T18:49:57.847" Score="7" Body="&lt;p&gt;My recommendation is: Join a glider club. This limits the expense and puts you into contact with many like-minded people. Make sure the club has several gliding instructors, so you will have enough chance for training lessons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did you try the &lt;a href=&quot;https://www.gliding.co.uk/club-finder&quot;&gt;UK gliding club finder&lt;/a&gt; yet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I prefer gliders over powered aircraft because they expose you to the weather and the laws of aerodynamics much more directly. Also, the expenses per hour are much lower. At most clubs, you can expect to pay around £20 per hour to hire a glider, around £30 for an aerotow launch and around £8 for a winch launch.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-10-27T18:55:00.820" LastActivityDate="2014-10-27T18:55:00.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9355" PostTypeId="1" CreationDate="2014-10-27T22:38:48.110" Score="3" ViewCount="626" Body="&lt;p&gt;I am a filmmaker who made a film most pilots have seen (405) &lt;a href=&quot;http://youtu.be/Tpx6o4gvmXE&quot; rel=&quot;nofollow&quot;&gt;http://youtu.be/Tpx6o4gvmXE&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am working a new production that also takes place aboard an airliner. In it a telekinetic little girl is overriding the flight controls. But it is thought to be some sort of electronic control interference for a short time. Are there procedures a flight crew would follow in the initial stages if their controls seemed &quot;possessed?&quot;&lt;/p&gt;&#xA;" OwnerUserId="4080" LastEditorUserId="1467" LastEditDate="2015-04-17T07:49:23.820" LastActivityDate="2015-04-17T07:49:23.820" Title="Are there procedures to follow in case of a suspect Electronic Control override (hacking)?" Tags="&lt;emergency&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9356" PostTypeId="2" ParentId="9340" CreationDate="2014-10-27T23:03:56.887" Score="8" Body="&lt;p&gt;Running the numbers from &lt;a href=&quot;https://aviation.stackexchange.com/a/9341/946&quot;&gt;RedGrittyBrick's answer&lt;/a&gt;, there appear to be 36 active 747-200s out of 393 built (according to Wikipedia). Of the 36, 9&amp;nbsp;are passenger planes, 22&amp;nbsp;freight (including 6&amp;nbsp;converted from passenger planes, marked &lt;sup&gt;*&lt;/sup&gt;), 3&amp;nbsp;combi (passenger and freight), and the two VC-25As (&quot;Air Force One&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The active aircraft are as follows, with tail numbers included so you can look for photos.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aerospace One: 1 freight (SX-ASO), 1 combi (SX-ASC)&lt;/li&gt;&#xA;&lt;li&gt;AHS Air International: 1 freight (AP-BIO)&lt;/li&gt;&#xA;&lt;li&gt;Cargo Air Lines: 1 combi (4X-ICM)&lt;/li&gt;&#xA;&lt;li&gt;Caspian Airlines: 1 freight (EP-CQA)&lt;/li&gt;&#xA;&lt;li&gt;Iran Air: 3 passenger (EP-IAG, EP-IAH, EP-IAI), 1 combi (EP-ICD)&lt;/li&gt;&#xA;&lt;li&gt;Jet Star: 1 freight (ER-BBS)&lt;/li&gt;&#xA;&lt;li&gt;Kabo Air: 3 passenger (5N-DKB, 5N-JRM, 5N-MAD)&lt;/li&gt;&#xA;&lt;li&gt;Kalitta Air: 2 passenger (N715CK, N793CK), 4 freight (N704CK, N746CK, N794CK,&lt;sup&gt;*&lt;/sup&gt; N795CK&lt;sup&gt;*&lt;/sup&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Kam Air: 1 freight (4L-TZS)&lt;/li&gt;&#xA;&lt;li&gt;Midex Airlines: 3 freight (A6-MDG, A6-MDH, A6-MDI)&lt;/li&gt;&#xA;&lt;li&gt;Orient Thai Airlines: 1 passenger (HS-UTC)&lt;/li&gt;&#xA;&lt;li&gt;Rayyan Air&lt;sup&gt;**&lt;/sup&gt;: 2 freight (AP-BKI, AP-BKS&lt;sup&gt;*&lt;/sup&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Saha Airlines: 2 freight (EP-SHB, EP-SHH)&lt;/li&gt;&#xA;&lt;li&gt;Saudi Arabian Airlines: 1 freight (HZ-AIU)&lt;/li&gt;&#xA;&lt;li&gt;United States Air Force: 2 VC-25A (82-8000, 92-9000)&lt;/li&gt;&#xA;&lt;li&gt;Uni-Top Airlines: 3 freight (B-2448,&lt;sup&gt;*&lt;/sup&gt; B-2450,&lt;sup&gt;*&lt;/sup&gt; B-2462)&lt;/li&gt;&#xA;&lt;li&gt;Veteran Avia: 1 freight (EK74799&lt;sup&gt;*&lt;/sup&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Vision Air International: 1 freight (AP-BIV)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;*&lt;/sup&gt; Built as passenger and converted to freight.&lt;BR&gt;&#xA;&lt;sup&gt;**&lt;/sup&gt; Not to be confused with Ryanair! :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also several stored aircraft, including the Rolls-Royce test plane you mention in the question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Thanks to &lt;a href=&quot;https://aviation.stackexchange.com/users/1696/fooot&quot;&gt;fooot&lt;/a&gt; for explaining that BSF denotes &quot;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/FR-2012-08-08/html/2012-18627.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing Special Freighter&lt;/a&gt;&quot;, a passenger plane &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/3064296/&quot; rel=&quot;nofollow noreferrer&quot;&gt;converted to freight use&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-10-28T16:18:11.910" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9357" PostTypeId="1" AcceptedAnswerId="9358" CreationDate="2014-10-27T23:40:56.430" Score="16" ViewCount="17484" Body="&lt;p&gt;So, I was re-watching The Hunt For Red October, (in light of current Russian shenanigans with Sweden), and there was a scene in which a crew-member on the ground was electrocuted by making contact (and presumably grounding) the helicopter, which had picked up a charge in the stormy weather. Can anyone explain more of what is going on here?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="1467" LastEditDate="2018-12-03T07:13:42.393" LastActivityDate="2021-04-13T12:48:25.700" Title="Can rotorcraft pick up a dangerous electric charge?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;electrical-system&gt;&lt;static-electricity&gt;" AnswerCount="9" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9358" PostTypeId="2" ParentId="9357" CreationDate="2014-10-28T00:28:45.750" Score="19" Body="&lt;p&gt;In the same way than an aircraft will build static charge on the wings from friction with the air, the same thing can happen with helicopters from fast moving blades.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;From a 1962 US Army document:&lt;/em&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Any aircraft flying in the atmosphere can be considered as a conductive body located in a highly electrically insulated environment. In such a body, electrostatic charge is generated by three principal mechanisms:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Charge transfer created by a triboelectric effect between the aircraft and the atmospheric particles, such as dust, water, water vapor, snow, etc.&lt;/li&gt;&#xA;&lt;li&gt;Unbalance of the ionic content of the exhaust gases produced by the aircraft engine(s).&lt;/li&gt;&#xA;&lt;li&gt;Induction charge due to high electrostatic&#xA;field gradients which are found occasionally in the aircraft flight path.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/406212.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here's a more detailed photo of the US army discharging a helicopter while wearing insulating gloves:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/km1NW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/km1NW.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt; SGT Nathan Rodeheaven uses a static probe to discharge static electricity from a UH-60 Black Hawk before his teammate, PV2 Danny Browning, hooks up the cargo to the helicopter. The safety measure prevents the hook-up man from being electrocuted in the event there is accumulated static electricity. Photo: Kristin Molinaro &lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-12-03T12:34:04.060" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9359" PostTypeId="2" ParentId="9357" CreationDate="2014-10-28T00:30:09.853" Score="-1" Body="&lt;p&gt;It sounds like the helicopter had no static dissipators/wicks fitted (or broken ones!), and this resulted in the normal in-flight charge buildup zapping the groundman on the submarine instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm surprised the helicopter pilots didn't notice that awful noise in their radios well before this became a problem, though!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/2720/what-are-these-things-hanging-off-the-trailing-edge-of-the-wing/2721#2721&quot;&gt;What are these things hanging off the trailing edge of the wing?&lt;/a&gt; for more details.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-10-28T00:30:09.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9360" PostTypeId="2" ParentId="9357" CreationDate="2014-10-28T00:32:13.560" Score="10" Body="&lt;p&gt;Helicopters in normal weather will build up a static charge, just ask &lt;a href=&quot;https://www.youtube.com/watch?v=eW5p70b9RjE&quot; rel=&quot;noreferrer&quot;&gt;any ground crew for a logging helicopter.&lt;/a&gt; Normally the hook will be grounded by dropping it on the ground before the hooker will touch it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or a grounding rod will be used to neutralize the static charge.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-28T00:32:13.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9361" PostTypeId="1" AcceptedAnswerId="9362" CreationDate="2014-10-28T00:46:18.983" Score="21" ViewCount="3104" Body="&lt;p&gt;Some airports operate simultaneous take off and landing on parallel but close runways. By close, I mean like the &lt;a href=&quot;http://en.wikipedia.org/wiki/File:LAX_Airport_Diagram.svg&quot;&gt;pairs of runways at LAX&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What if a landing aircraft makes a go-around at the same time as another aircraft takes off? How is separation maintained? Would it be enough for the missed approach procedure to specify turning away from the departure runway?&lt;/p&gt;&#xA;" OwnerUserId="4083" LastEditorUserId="22726" LastEditDate="2018-06-05T17:45:46.930" LastActivityDate="2018-06-05T17:45:46.930" Title="How are go-arounds safe with close parallel runways?" Tags="&lt;safety&gt;&lt;runways&gt;&lt;go-around&gt;&lt;parallel-runways&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9362" PostTypeId="2" ParentId="9361" CreationDate="2014-10-28T01:43:11.880" Score="15" Body="&lt;p&gt;The first thing I would point out is that LAX isn't going to be running simultaneous approaches on 24L &lt;em&gt;and&lt;/em&gt; 24R or 25L &lt;em&gt;and&lt;/em&gt; 25R. They'll select one of each of the parallel sets for the landing runways (typically the outer runways), and one of each for departing runways (typically the inner runways). For example, they might be landing on 25L and 24R and departing 25R and 24L. So, there's quite a bit of distance between those runways, and very little risk in a go around situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a diagram illustrating LAX's typical arrival/departure runway usage to make it more visually apparent what I mean:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PgNsW.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second part of your question about an aircraft taking off at the same time as a go-around certainly happens, and when it does, ATC needs to take action to ensure safety and separation. ATC separation requirements can be satisfied by altitude, distance, or divergence (and, in some cases, visual contact). In the situation you described, divergence is the quickest and safest way to achieve separation. I believe the requirement is 30°, so tower would typically order a go-around and order a new heading at least 30° off of runway heading. The geography of the area, layout of the airspace, and the approach patterns would likely dictate the exact procedure used at each airport since their two primary goals, in order, are going to be 1. safety, and 2. getting them back in the approach sequence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the LAX example, a go-around on 24R would most likely get a right turn, and 25L would most likely get  left turn (away from the airport) so as not to conflict with other departing or arriving traffic. This is one of a few reasons the outer runways are preferred for landing.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2014-10-28T15:21:21.040" LastActivityDate="2014-10-28T15:21:21.040" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9364" PostTypeId="1" CreationDate="2014-10-28T06:53:07.553" Score="5" ViewCount="283" Body="&lt;p&gt;As a GA pilot who rents planes occasionally, I am looking at buying a renter's insurance policy so that I'm covered against the injury of any passengers as well as damage to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For bodily injury, I based the amount off of my car insurance. That is, in the neighborhood of $100,000/person. Is that assumption correct?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I don't know is what level of aircraft damage liability is an acceptable amount. I mostly fly Cessna 152s, 172s, and Piper Warriors. Of course, it isn't worth paying for a liability that is more than the plane is worth. So what would be a good level of liability to be covered for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, I understand that an FBO will have insurance on its planes. However, this insurance is to protect the FBO, not the pilot. Should the FBO's insurance affect the level of insurance I, as a renter, choose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, &lt;a href=&quot;https://www.avemco.com/aircraft-renters-insurance/cost-quote-rates.aspx&quot; rel=&quot;nofollow&quot;&gt;here are Avemco's&lt;/a&gt; current annual damage liability rates for single engine planes:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Limit      Premium&#xA;-------------------&#xA;$1,000     $60&#xA;$5,000     $120&#xA;$10,000    $155&#xA;$15,000    $210&#xA;$20,000    $220&#xA;$25,000    $275&#xA;$30,000    $310&#xA;$35,000    $365&#xA;$40,000    $415&#xA;$45,000    $465&#xA;$50,000    $500&#xA;$55,000    $540&#xA;$60,000    $560&#xA;$65,000    $605&#xA;$70,000    $675&#xA;$75,000    $725&#xA;$80,000    $745&#xA;$100,000   $925&#xA;$150,000   $1,400&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="2183" LastEditorUserId="65" LastEditDate="2014-10-28T13:02:08.810" LastActivityDate="2014-10-28T13:02:08.810" Title="What level of liability should a GA renter's insurance policy have?" Tags="&lt;general-aviation&gt;&lt;liability&gt;&lt;insurance&gt;&lt;renters-insurance&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2014-10-28T20:38:39.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="9365" PostTypeId="2" ParentId="9361" CreationDate="2014-10-28T07:32:25.613" Score="6" Body="&lt;p&gt;Adding some more information to Bret's answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at both ILS approach charts for Munich's runways &lt;a href=&quot;http://www.vacc-sag.org/airport/EDDM&quot;&gt;26L and 26R&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt;, which are parallel runwawys. Both ILS instrument approaches terminate at the &lt;a href=&quot;http://en.wikipedia.org/wiki/Missed_approach&quot;&gt;Missed Approach Point (MAPt)&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see from the charts that the Missed Approach for the northern runway 26R mandates a right turn to the MIKE (MIQ) NDB after passing 1.0 DME of the Munich (DMN) DME. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see from the charts that the Missed Approach for the southern runway 26L mandates a left turn to the Munich (MUN) VOR after passing 1.0 DME of the Munich (DMS) DME.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event that you have an arrival to the northern runway and a departure from the southern runway that would use a northern &lt;a href=&quot;http://en.wikipedia.org/wiki/Standard_instrument_departure_%28SID%29&quot;&gt;Standard Instrument Departure&lt;/a&gt;, such as the &lt;a href=&quot;http://www.vacc-sag.org/airport/EDDM&quot;&gt;ANKER6S Departure&lt;/a&gt;, you could instruct the aircraft on the departure to maintain runway track or continue on a heading to establish separation between both aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tower and Approach controllers develop a contingency plan when working with arrivals and departures in their head, which they can quickly deploy to establish and maintain separation by using standard procedures or vectors.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;The source I am providing here is a simulation resource. While the charts are as close to the real-world counterpart as possible, they are not to be used for real-world aviation, but will serve their purpose for visually supporting the answer and are easily accessible.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-10-28T07:32:25.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9367" PostTypeId="1" AcceptedAnswerId="9369" CreationDate="2014-10-28T08:36:19.920" Score="8" ViewCount="1705" Body="&lt;p&gt;Aircraft operating in icy conditions are equipped with &lt;a href=&quot;http://en.wikipedia.org/wiki/Ice_protection_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;de-icing equipment&lt;/a&gt; to remove ice from specific parts of the aircraft (wing, sensors,...) in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is snow or icy conditions while the aircraft is still on ground, it is de-iced with &lt;a href=&quot;http://en.wikipedia.org/wiki/De-ice&quot; rel=&quot;nofollow noreferrer&quot;&gt;ground equipment&lt;/a&gt; (de-ice fluid, &lt;a href=&quot;https://aviation.stackexchange.com/questions/200/how-do-you-handle-frost-on-a-plane&quot;&gt;towel&lt;/a&gt;,...). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the aircraft's own de-icing equipment also used? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this equipment enough to de-ice an aircraft before take-off (lets say if this is a sunny day and the temperature is just below 0°C)?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-01T07:36:38.390" Title="Is on-board equipment for in-flight de-icing also used on the ground?" Tags="&lt;icing&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9369" PostTypeId="2" ParentId="9367" CreationDate="2014-10-28T10:12:22.233" Score="12" Body="&lt;p&gt;Usually, no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two main methods used to deice an airplane in the air. One is letting warm air that is bleed from the jet engine to heat the wing leading edge. The other is to have have rubber air bladders (called deice boots) on the leading edge of the wing and tail surfaces that are pumped up and the ice falls off. Both of those methods are only useful to deice the leading edge of the wing and tail surfaces which is pretty much the only dangerous place where an airplane can gather ice while it is flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes on the ground are a different story. Ice can be built up pretty much anywhere as there is no airflow to prevent it. Excessive ice on control surfaces can make them behave &quot;unevenly&quot; or in extreme cases even unresponsive. Bigger chunks of ice breaking off the fuselage can get ingested by the engine and cause problems. It is therefore important that the airplane takes off ice-free. In fact, as little as frost on the surface of the wings can cause a significant loss of lift and can even cause a plane to crash. &lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="-1" LastEditDate="2015-01-01T07:36:38.390" LastActivityDate="2015-01-01T07:36:38.390" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9372" PostTypeId="2" ParentId="9367" CreationDate="2014-10-28T15:17:15.290" Score="5" Body="&lt;p&gt;Yes, anti-ice equipment is sometimes used on the ground, but is usually not sufficient to clear the plane of ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane systems are generally referred to as &lt;strong&gt;anti&lt;/strong&gt;-ice, because they are designed to prevent ice from forming or accumulating. Airport equipment is referred to as &lt;strong&gt;de&lt;/strong&gt;-ice, because it is designed to remove ice as well as preventing it from forming (to some degree). So, as others have said, the real de-icing equipment available on the ground is much more effective than what is on the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anti-ice systems are generally designed to protect key areas of the airplane where ice is most likely to form in flight; leading edges of the wings, engine cowls/props, and pitot-static or other sensors. However, on the ground, it will accumulate on other exposed surfaces like wings/stabilizers/fuselage. This is why the de-ice measures are needed, to clear off those surfaces as well, because ice on the &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Eagle_Flight_4184&quot; rel=&quot;nofollow noreferrer&quot;&gt;wings&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Ontario_Flight_1363&quot; rel=&quot;nofollow noreferrer&quot;&gt;is&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/USAir_Flight_405&quot; rel=&quot;nofollow noreferrer&quot;&gt;bad&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, anti-ice equipment may be used on the ground as well when needed. &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Florida_Flight_90&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Florida Flight 90&lt;/a&gt; crashed shortly after takeoff in icing conditions, and a contributing factor was ice accumulating on engine sensors which prevented the engines from providing full thrust. So when icing is expected, the anti-ice systems will certainly be used on the ground to provide added protecting to the most critical surfaces, in addition to the protection from de-icing procedures. Failing to have the wing and control surfaces properly de-iced also contributed to that accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see this related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/3844/why-turn-off-pitot-tube-heating&quot;&gt;Why turn off pitot tube heating?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-10-28T15:17:15.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9373" PostTypeId="2" ParentId="9355" CreationDate="2014-10-28T17:56:35.963" Score="6" Body="&lt;p&gt;There are procedures for when some instrument indicates false values for how to find which one is not to be trusted and what to do if particular instrument cannot be trusted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for primary flight controls, not really. If the aircraft is flying on autopilot and initiates unexpected manoeuvre, the pilot will hit the autopilot disconnect button and take over manually. But beyond that, the pilot will just try more pressure on the controls to get the plane where he needs to. And won't really have much time to think about the reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may want to look at the incidents and accidents caused by &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_rudder_issues&quot;&gt;B737 rudder reversal&lt;/a&gt;. The rudder suddenly deflected in opposite direction than commanded and the pilots were not really able to understand what is happening in the short time they had to react. Somewhat similar incidents where the rudder failures of B747 (&lt;a href=&quot;http://en.wikipedia.org/wiki/Northwest_Airlines_Flight_85&quot;&gt;Northwest 85&lt;/a&gt;, here is &lt;a href=&quot;http://jalopnik.com/5629528/how-i-saved-a-747-from-crashing&quot;&gt;captains account of the incident&lt;/a&gt;; there was one other similar occurrence). Again, the pilots just fought the controls; finding out what happened was not really possible and wouldn't help much anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'd say there is really no time to &quot;think it to be some sort of electronic control interference&quot;. The pilots would simply disconnect autopilot (if it didn't disconnect already due to pressure on controls) and then they would fight the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in all aircraft except Airbus A320 and newer and Boeing 777 and 787 the control column is mechanically (cables in smaller aircraft, hydraulically with some kind of power amplification on larger ones) connected to the control surfaces. So the pilots would be directly fighting the telekinetic power with their muscles. On Boeing 777 and 787 there is electronic intermediary, but the link is still bidirectional and control column position still corresponds to control surface position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only Airbus A320 and newer has the side-stick connected to a computer that calculates the final command from the pilot input and inertial reference. In this case the telekinet would either try to move the surfaces, but then would be fighting the computer, which has all power of the hydraulic system to it's disposal, or would try to move the side-stick under pilot's hand, but then the other pilot could press control priority button to take over. Of course even on Airbus the pilots can pull the circuit breaker and disable the computer, but then they are left with trim wheels and rudder pedals that both &lt;em&gt;do&lt;/em&gt; have direct hydraulic links.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-10-28T18:13:51.847" LastActivityDate="2014-10-28T18:13:51.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9374" PostTypeId="2" ParentId="9353" CreationDate="2014-10-28T17:59:04.847" Score="4" Body="&lt;p&gt;There are a number of ways to 'get in the air'. Peter's mention of gliding is a good one. The requirements to get a glider license are substantially lower than any of the routes to a powered license. However it has obvious restrictions on weather, distance passengers etc. Time spent flying a glider will not count towards your requirements for a powered license if you decide to get one (though obviously many of the skills are transferrable). Gliding is also cheaper than other forms of aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next easiest way to get into the air is through a microlight permit. That's slightly more regulated than a glider, with slightly higher requirements, but also has restrictions on speed, passengers distance, weather, comfort etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The route with the highest requirements to get qualified, and also the highest cost, is the private pilots license. However that will get you the ability to fly an aircraft with a much higher comfort, capability and performance level. It's also opens up the route to more certifications - twin engines, instrument flying, commercial flying and even airlines (technically you can be a commercial glider or microlight pilot, but it's much rarer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only you can decide which route you prefer, taking into account all the factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to find out about how you could achieve each one is to &lt;strong&gt;visit a club or a school where they do each&lt;/strong&gt;. There are flying clubs or schools at virtually every working airport, and the internet will give you a list of glider or microlight clubs.&lt;/p&gt;&#xA;" OwnerUserId="289" LastActivityDate="2014-10-28T17:59:04.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9375" PostTypeId="1" AcceptedAnswerId="9380" CreationDate="2014-10-28T18:24:56.457" Score="10" ViewCount="3291" Body="&lt;p&gt;Distantly related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/8750/why-do-ga-pilots-in-europe-operate-n-reg-us-aircraft&quot;&gt;this question&lt;/a&gt;, but can a non-US citizen (or corporation) own an N-registered aircraft?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-09-21T17:54:31.907" Title="Can a non-US citizen (or entity) own an N-registered aircraft?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9376" PostTypeId="1" AcceptedAnswerId="9378" CreationDate="2014-10-28T18:44:52.317" Score="18" ViewCount="6297" Body="&lt;p&gt;On a cold night or if it's been snowing, jets are sprayed with orange de-icing fluid:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YVNwQ.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why is it orange?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's to see where's been sprayed and where you've missed a bit, black would be the most contrasting colour on white; while yellowy-green is the strongest/most visible colour to the human eye; and blue is the least affected colour for colour-blind people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just curious as to why orange.&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-10-28T20:37:57.403" Title="Why is the de-icing fluid sprayed on jets coloured orange?" Tags="&lt;aviation-history&gt;&lt;jet&gt;&lt;ground-operations&gt;&lt;anti-ice&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9377" PostTypeId="2" ParentId="9355" CreationDate="2014-10-28T18:49:33.757" Score="4" Body="&lt;p&gt;I think there are a variety of ways to do what you want. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You can have the girl take over the autopilot, rather than the controls, and prevent the pilot from disconnecting the autopilot. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Or you can have her physically take over the controls themselves (telekinesis), and the autopilot will automatically disconnect when pressure is applied to the controls&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Or you can have it be a fly-by-wire aircraft (hello Airbus), and have the girl take over the fly-by-wire system, bypassing both the autopilot and the controls, and taking control of the control surfaces herself&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;you'll also have to figure out what you want to do regarding the throttles. Most passenger jets have autothrottles, but if someone is flying the plane by hand, and there is a change in altitude, then the throttles may need to be adjusted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of this is going to depend on whether the girl has power over physical objects, or the ability to control electronic energy, or both&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IIRC, there is an episode of &lt;em&gt;Firefly&lt;/em&gt; where River takes over the ship using her telepathic powers. Might be worth consulting.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-10-28T18:49:33.757" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9378" PostTypeId="2" ParentId="9376" CreationDate="2014-10-28T19:01:43.850" Score="25" Body="&lt;p&gt;There are actually &lt;a href=&quot;http://www.munich-airport.de/en/micro/efm/dienstleistungen/enteisen2/index.jsp&quot;&gt;two types of de-icing fluid&lt;/a&gt;, one is orange and one is green. According to a &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=4&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CD0QFjAD&amp;amp;url=http%3A%2F%2Fwww.dow.com%2Fwebapps%2Flit%2Flitorder.asp%3Ffilepath%3Dproductsafety%2Fpdfs%2Fnoreg%2F233-00609.pdf%26pdf%3Dtrue&amp;amp;ei=3OZPVO2GBYTYggS6uIToDw&amp;amp;usg=AFQjCNEquWaaq2ZhPZ2z_iyeszTAzssu5A&amp;amp;sig2=w3t_JftMFkgMFGES7ZReIQ&amp;amp;bvm=bv.77880786,d.eXY&quot;&gt;product safety sheet&lt;/a&gt; for one brand:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The dye is intended to indicate which parts of the  aircraft have been&#xA;  treated and to differentiate between fluids (Type I fluids are orange,&#xA;  Type IV  fluids are green).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As to why orange and green, presumably they aren't easily confused with other liquids used around aircraft. Black would look like oil or another fluid if it pooled on tarmac, hydraulic fluids or oils are often yellow/green in colour and blue is a very common colour in aircraft painted liveries. So I guess that orange and green were sort of the ones 'left over' after all the other obvious colours had been considered.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-28T19:01:43.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9379" PostTypeId="1" AcceptedAnswerId="9384" CreationDate="2014-10-28T19:35:17.123" Score="7" ViewCount="16037" Body="&lt;p&gt;What radio frequencies are used for air-to-air intercom in formation flying? I assume there is a difference between military and civil aviation (e.g a group of GA aircrafts flying as a formation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a couple of civil UNICOM frequencies &lt;a href=&quot;http://www.smeter.net/spectrum/aviation.php&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; (e.g. 122.8 MHz, 122.975 MHz, ...). 122.750 MHz (Aviation Air to Air Communications) seems to be what I am looking for (correct?). But what if there is more than one team?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also wonder if in military or professional formations (aerobatic formations) something outside the Very High Frequency (VHF) Aviation Band is used (to provide better quality, e.g. digital communication).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.monitoringtimes.com/html/mtMilVHF.html&quot; rel=&quot;noreferrer&quot;&gt;this article&lt;/a&gt; I can see lot of military frequencies, but not telling me what to use for military formation flying.&lt;/p&gt;&#xA;" OwnerUserId="4024" LastEditorUserId="97" LastEditDate="2014-10-28T19:49:51.063" LastActivityDate="2018-04-30T02:49:08.303" Title="What radio frequencies are used for intercom in formation flying?" Tags="&lt;radio-communications&gt;&lt;flying-in-formation&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9380" PostTypeId="2" ParentId="9375" CreationDate="2014-10-28T19:37:07.663" Score="4" Body="&lt;p&gt;Nothing in the regulations seems to preclude it - but there are &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/register_aircraft/&quot; rel=&quot;nofollow&quot;&gt;some conditions you have to meet&lt;/a&gt; per the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;An individual who is a United States citizen,&lt;/li&gt;&#xA;  &lt;li&gt;A partnership each of whose partners is an individual who is a U.S. citizen,&lt;/li&gt;&#xA;  &lt;li&gt;A corporation or association:&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;organized under the laws of the U.S. or a State, the District of Columbia, or a U.S. territory or possession,&lt;/li&gt;&#xA;  &lt;li&gt;of which the president and at least two-thirds of the board of directors and other managing officers are U.S citizens, and&lt;/li&gt;&#xA;  &lt;li&gt;in which at least 75% of the voting interest is owned or controlled by persons that are U.S. citizens,&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;An individual citizen of a foreign country lawfully admitted for permanent residence in the U.S.&lt;/strong&gt;,&lt;/li&gt;&#xA;  &lt;li&gt;A U.S. governmental unit or subdivision&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;A non-U.S. citizen corporation organized and doing business under the laws of the U.S. or one of the States as long as the aircraft is&lt;br&gt;&#xA;  based and primarily used in the U.S.&lt;/strong&gt; (60% of all flight hours must be &#xA;  from flights starting and ending within the U.S.)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(emphasis added)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So Toyota could not buy an aircraft and register it to their main company in Japan  on the US registry, nor could they buy &amp;amp; register it under a US Subsidiary and subsequently fly it off to Japan to live out the rest of its days shuttling executives around Asia.&lt;br&gt;&#xA;A Toyota executive with Permanent Resident status could buy themselves a nice Cirrus and register it on the US Registry though.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-09-21T17:54:31.907" LastActivityDate="2015-09-21T17:54:31.907" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9381" PostTypeId="2" ParentId="9376" CreationDate="2014-10-28T20:26:49.577" Score="17" Body="&lt;p&gt;About your question on why black is not used even though it provides the highest contrast to white: thats not practically true. The problem is, that black and white have the same hue and color saturation (or rather they have no color saturation, and thus the hue is undefined in both cases), so they only differ in brightness/luminance. And a difference in brightness can easily be caused by different lighting conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So for black-dyed de-icing fluid, you couldn't reliably tell whether a black-looking spot has been de-iced, or if it is just not well lit. Similarly, a white-looking spot may not have been de-iced, or may just accidentally reflect more light that its surroundings (e.g. due to specular highlights, retro reflectors, different incidence angle to the light source, or different surface reflectance), Colored fluids solve that problem, as color (e.g. green dyed liquid vs. white snow) barely changes under varying lighting conditions.&lt;/p&gt;&#xA;" OwnerUserId="4097" LastEditorUserId="4097" LastEditDate="2014-10-28T20:37:57.403" LastActivityDate="2014-10-28T20:37:57.403" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9382" PostTypeId="1" CreationDate="2014-10-28T20:31:04.097" Score="4" ViewCount="1881" Body="&lt;p&gt;How close in time or distance will ATC let a pilot fly to the localizer, before cancelling the approach clearance, where the pilot has not reported being established? Is it the controller's call when to cancel the clearance? &lt;/p&gt;&#xA;" OwnerUserId="4098" LastEditorUserId="572" LastEditDate="2015-02-19T08:54:20.797" LastActivityDate="2015-04-07T23:28:58.530" Title="What criteria does ATC apply to determine if an aircraft is established on the localizer if the pilot does not report it?" Tags="&lt;air-traffic-control&gt;&lt;approach&gt;&lt;clearance&gt;&lt;localizer&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9383" PostTypeId="2" ParentId="9379" CreationDate="2014-10-28T20:40:35.000" Score="3" Body="&lt;p&gt;For general aviation, 122.75 is the official fixed wing air-to-air frequency designated by the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt47.5.87&amp;amp;rgn=div5#se47.5.87_1173&quot; rel=&quot;nofollow&quot;&gt;FCC&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC90-50D.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA&lt;/a&gt; (and 123.025 is for helicopters). There are also other frequencies allowed based on location (Hawaii, Los Angeles, and the Grand Canyon). Otherwise, you should probably ask around in the area in which you plan to operate. See if there is a frequency that is commonly used. &lt;a href=&quot;http://studentpilot.com/interact/forum/archive/index.php/t-12777.html&quot; rel=&quot;nofollow&quot;&gt;This thread&lt;/a&gt; mentions a few frequencies people have used. If you can find the frequencies used for a local air show, that could be a good indication of frequencies that would be free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aviation is going to vary a lot more. Typically UHF is used, but certainly VHF or digital could be used depending on the situation. Refueling tracks have designated areas and frequencies. Performing groups have a set of channels that they use when they fly. For regular formation flying though, it will probably vary more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://wiki.radioreference.com/index.php/Aircraft&quot; rel=&quot;nofollow&quot;&gt;RadioReference&lt;/a&gt; is a good place to look. 123.45 is listed as &quot;unofficial&quot; air to air and flight test. The military table lists 303.0 as a possibility.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-28T20:46:24.920" LastActivityDate="2014-10-28T20:46:24.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9384" PostTypeId="2" ParentId="9379" CreationDate="2014-10-28T20:43:07.117" Score="5" Body="&lt;p&gt;For the US, according to &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/AIM/aim0401.html#cn8gx1ccDefa&quot; rel=&quot;nofollow noreferrer&quot;&gt;section 4-1-11&lt;/a&gt; of the AIM (&lt;em&gt;Designated UNICOM/MULTICOM Frequencies&lt;/em&gt;) for private fixed-wing flights you should use 122.75:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air-to-air communication (private fixed wing aircraft): 122.750&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Air-to-air communications (general aviation helicopters): 123.025&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Aviation instruction, Glider, Hot Air Balloon (not to be used for&#xA;  advisory service): 123.300, 123.500&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have no idea what the military does and their tactical comms might even be encrypted anyway, but they frequently use UHF instead of VHF, at least in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nor do I know what to do if you have two formation flights at the same time, but I guess that in reality it's either an air show with some form of semi-official control and perhaps even NOTAMs, or it's something private and in that case people make their own arrangements, e.g. picking some frequency that doesn't overlap with any nearby assigned frequencies. Using 123.45 is apparently common, but definitely not official.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-VHF communications for private flights would be regulated by the FCC, not the FAA, and personally I'm not sure if the benefits would be worth the extra equipment and the risk of confusion, but then again I know nothing about formation flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's some useful information from the FAA in this &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/6050.32B%20Chg%201.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;policy order&lt;/a&gt; clarifying the use of 121.5 and 123.45. It says that 123.45 is for operational use in oceanic regions, and within the US it's reserved for &quot;non-government flight test operations&quot;. There's also an &lt;a href=&quot;https://www.faa.gov/about/initiatives/airshow/media/Air_Show_Freq_Request_Guidance.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA document&lt;/a&gt; on requesting temporary frequencies for airshows etc. but it's air to ground only.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-04-30T02:49:08.303" LastActivityDate="2018-04-30T02:49:08.303" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9385" PostTypeId="2" ParentId="9382" CreationDate="2014-10-28T21:07:17.597" Score="1" Body="&lt;p&gt;Each instrument approach consists of a lateral part and a vertical part, in the case of the ILS approach these are: localizer and glideslope. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are usually vectored to intercept the localizer approximately 1-2nm before the Final Approach Fix (FAF), where the glideslope is captured. Aircraft can be vectored onto the localizer as far as 20-25nm out, depending on terrain, localizer equipment and many other factors. If an aircraft is not established on the localizer, there is no point in continuing the approach, so it will be cancelled and the aircraft revectored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is established on the localizer, it will try to intercept the glideslope, which is the vertical guidance system in the ILS approach. For VOR/DME, LOC/DME, NDB/DME or RNAV approaches, the vertical guidance is either achieved through correlation of location to a specific altitude in the chart or technical means which do not require a glideslope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft passes the Final Approach Fix and does not seem to descend, it will be considered as not established and the approach clearance will be cancelled, instructing the aircraft to either follow the missed approach procedure or manually vectoring the aircraft for another approach.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-10-28T21:07:17.597" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="9387" PostTypeId="2" ParentId="9382" CreationDate="2014-10-28T21:53:44.490" Score="1" Body="&lt;p&gt;I'm not 100% sure that I understand your question, but I think you're asking this: if a pilot is on a localizer or ILS approach but doesn't report established, when will ATC cancel his clearance and instruct him to go missed or vector him? But you didn't clarify if the pilot is actually &lt;em&gt;flying&lt;/em&gt; the approach correctly or not, where he started the approach, if he's being vectored, what his current clearance is etc. so I'm not sure I understand the scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I couldn't find a definitive, objective answer to this and I'd be surprised if there is one. If a pilot deviates from an approach procedure in any way, then the controller has to make a judgement call based on current traffic, workload, terrain, student pilots etc. and I think it's unlikely that there could be a single, definite rule on what to do when.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from any other considerations, if the pilot doesn't report established it could be a comms failure and there are procedures for that: in this case since he was already cleared for the approach (presumably) the controller will expect him to continue. And if the pilot deviates without comms, there isn't much the controller can do anyway apart from clear the surrounding airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, the FAA &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0509.html#CBA320ROBE&quot; rel=&quot;nofollow&quot;&gt;procedures for controllers&lt;/a&gt; give this instruction for handling aircraft on a radar arrival - i.e. under direct ATC control - and it seems plausible that they would apply it in other cases too:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. If deviations from the final approach course are observed after&#xA;  initial course interception, apply the following:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Outside the approach gate: apply procedures in accordance with subpara a, if necessary, vector the aircraft for another approach.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Inside the approach gate: inform the pilot of the aircraft's position and ask intentions.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&quot;subpara a&quot; simply says that the controller should provide suitable vectors with a maximum 30° intercept angle to the final approach course. The approach gate &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow&quot;&gt;is&lt;/a&gt; defined in the P/CG:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;APPROACH GATE&lt;/strong&gt;- An imaginary point used within ATC as a basis for&#xA;  vectoring aircraft to the final approach course. The gate will be&#xA;  established along the final approach course 1 mile from the final&#xA;  approach fix on the side away from the airport and will be no closer&#xA;  than 5 miles from the landing threshold.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-07T23:28:58.530" LastActivityDate="2015-04-07T23:28:58.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9388" PostTypeId="2" ParentId="9379" CreationDate="2014-10-28T21:56:50.757" Score="3" Body="&lt;p&gt;With respect to military aviation, it's going to depend on the radio capabilities of the aircraft involved in the formation. fooot's answer mentions that typically UHF is used. That is sort of true - UHF is generally used for military ATC, RAPCON, etc, but as far as aircraft-to-aircraft, it will depend on the capabilities of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many large aircraft have multiple radios, UHF and VHF, as well as digital radios, so depending on the mission, they may use a specified area frequency, or a &quot;local&quot; frequency, or a specific military channel. With smaller aircraft, such as trainers and fighters, they may only have 1 of each (UHF/VHF), so with the need to monitor the controlling agency, that may drive the &quot;formation frequency&quot; to using a VHF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regards to specific channels in that article, it will vary from location to location, as different bases/squadrons/aircrafts will have different frequencies designated for formations. So there's no real way to know &quot;in general&quot; - it would be a localism.&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2014-10-28T21:56:50.757" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9389" PostTypeId="1" CreationDate="2014-10-28T23:28:21.207" Score="6" ViewCount="589" Body="&lt;p&gt;Do you need FAA approval to land a helicopter on Miami Beach, Florida?&lt;/p&gt;&#xA;" OwnerUserId="4100" LastEditorUserId="97" LastEditDate="2014-10-29T01:06:51.473" LastActivityDate="2014-10-29T01:06:51.473" Title="Do you need FAA approval to land a helicopter on Miami Beach?" Tags="&lt;faa-regulations&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9390" PostTypeId="2" ParentId="9389" CreationDate="2014-10-28T23:42:54.923" Score="3" Body="&lt;p&gt;If you are in an emergency then get on the ground and deal with the fallout after everyone is safe and sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides that it's the land owner's call about whether you can land on his property, otherwise you will be trespassing with all due consequences.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-28T23:42:54.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9391" PostTypeId="2" ParentId="9389" CreationDate="2014-10-29T00:03:40.150" Score="5" Body="&lt;p&gt;No; you may need permission from the local authority.  FAA doesn't regulate where you can land or take off.&lt;/p&gt;&#xA;" OwnerUserId="3417" LastActivityDate="2014-10-29T00:03:40.150" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9393" PostTypeId="1" AcceptedAnswerId="9403" CreationDate="2014-10-29T01:27:07.493" Score="22" ViewCount="11761" Body="&lt;p&gt;I was watching a documentary on aircraft incidents which mentioned that the 737 does not have the facility to dump fuel. Instead they're required to fly in circles to burn off excess fuel in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It strikes me as a little odd, as someone without detailed knowledge of the 737-series' fuel systems, that the world's most popular passenger jet doesn't have this capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What was the design consideration/reasoning for this?&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2014-10-29T11:03:05.733" LastActivityDate="2019-08-22T19:41:35.450" Title="Why doesn't the 737 have a fuel dump nozzle?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;fuel-dumping&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9394" PostTypeId="1" AcceptedAnswerId="9397" CreationDate="2014-10-29T02:02:07.687" Score="9" ViewCount="2089" Body="&lt;p&gt;LOT 16 was a 767 which experienced a hydraulic leak, resulting in the failure of the landing gears and the proceeding belly landing shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/scUoqzG67-w?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why did the backup system(s) fail? I was under the impression that a gravity/freefall backup is mandatory.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="14897" LastEditDate="2018-01-14T15:04:32.150" LastActivityDate="2018-01-14T15:04:32.150" Title="Why did the backup landing gear deployment fail on LOT 16?" Tags="&lt;landing-gear&gt;&lt;accidents&gt;&lt;boeing-767&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9395" PostTypeId="2" ParentId="9394" CreationDate="2014-10-29T02:45:32.110" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/LOT_Polish_Airlines_Flight_16&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia says&lt;/a&gt;,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Shortly after the evacuation, a team from the Polish State Commission for Aircraft Accident Investigation arrived, and discovered that the C829 circuit breaker, which protects a number of systems including the alternate landing gear extension system was &amp;quot;popped&amp;quot;. The C4248 breaker for the alternate landing gear remained closed.&lt;/p&gt;&#xA;&lt;p&gt;After the plane was lifted off the runway, the C829 circuit breaker was closed, and the landing gear was extended, using the alternate system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="556" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-29T02:45:32.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9396" PostTypeId="2" ParentId="9393" CreationDate="2014-10-29T07:56:38.803" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 25.1001 Fuel jettisoning system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) If the maximum takeoff weight is more than 105 percent of the&#xA;  maximum landing weight, there must be a fuel jettisoning system able&#xA;  to jettison enough fuel to bring the takeoff weight down to the&#xA;  maximum landing weight. The average rate of fuel jettisoning must be&#xA;  at least 1 percent of the maximum takeoff weight per minute, except&#xA;  that the time required to jettison the fuel need not be less than 10&#xA;  minutes. This must be shown at maximum takeoff weight, with flaps and&#xA;  landing gear up, and in-- {balance deleted for brevity]&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;version of 25.1001 effective on 02/01/1965.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems that the 737 and also the 757 fit in that Regulation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 very nice Regulation Documents&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.us-caw.org/pdf/Fueldump.pdf&quot;&gt;United States Environmental Protection Agency&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/faqs/fueldump.pdf&quot;&gt;Boeing Commercial Airplanes from February 2014&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-10-29T08:11:25.557" LastActivityDate="2014-10-29T08:11:25.557" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9397" PostTypeId="2" ParentId="9394" CreationDate="2014-10-29T08:23:02.417" Score="18" Body="&lt;p&gt;Gravity/freefall backup (or more precisely &lt;em&gt;some&lt;/em&gt; backup) is mandatory, but in large aircraft running pulley from cockpit to the wheel wells to release the uplock (the thing that keeps the gear retracted) mechanically would be too complicated or the force required to operate it too large, so the uplock still needs to be released electrically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately the circuit breaker that protects the circuit responsible for releasing the uplock was &quot;popped&quot; (open), so the uplocks didn't release and the gear didn't fall down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew was trying to troubleshoot the issue for 80 minutes and consulted maintenance over radio, but because the checklists for either central hydraulic system (which does the normal gear extension) failure or alternate gear extension did not mention the circuit breaker (C829) neither crew nor maintenance thought of checking it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not possible to find why and when the breaker popped. They tested the alternate extension afterwards and it worked, but the breaker covers several other circuits and there could have been transient problem somewhere or it could have been maintenance error or some other reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read excerpt from the report on &lt;a href=&quot;http://avherald.com/h?article=4456bd6b&quot; rel=&quot;noreferrer&quot;&gt;The Aviation Herald&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-05-14T13:35:00.593" LastActivityDate="2016-05-14T13:35:00.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9398" PostTypeId="2" ParentId="9361" CreationDate="2014-10-29T08:32:34.787" Score="2" Body="&lt;p&gt;Also a big Problem exists at Zurich Airport where they must wait until a Landing on 14 is completed before they can give start-clearance on 16. This is due to the problem if an Airplane wants to land on 14 must make a go-around and the plane on 16 starts simultaneous, a possibility of a conflict can occur in mid-air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BGy24.png&quot; alt=&quot;Zhr&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit clarification according to my comments:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Normal Route is that Airplanes taking of on RWY16 &lt;a href=&quot;http://www.zurich-airport.com/the-company/media/news-center/2014/jun/140625-mm-neue-definition-startroute-16&quot; rel=&quot;nofollow noreferrer&quot;&gt;(they changed it&#xA;  slightly on march 2014)&lt;/a&gt; have to turn left, Zurich is famous that a&#xA;  plane taking off on RWY 16 will fly over the Airport at a much higher&#xA;  Attitude :&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Out of a Pilot Briefing: All SID out of runway 16 describes shortly&#xA;  after airborne a left turn to avoid noise emissions over the city of&#xA;  Zurich. This procedure often causes difficulties because it is hard to&#xA;  integrate in the FMS. Therefore, we recommend you to fly that left&#xA;  turn manually or with the heading function of the autopilot. Take&#xA;  caution to not turn right! The SIDs out of runway 34 is more or less a&#xA;  long left turn and normally no problem for the FMS. Stay on the Tower&#xA;  frequency until advised.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-10-29T16:04:48.570" LastActivityDate="2014-10-29T16:04:48.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9400" PostTypeId="1" AcceptedAnswerId="11293" CreationDate="2014-10-29T11:19:58.607" Score="5" ViewCount="1641" Body="&lt;p&gt;On a flight at the end of the 90s,  the plane --  most likely a 747 -- made a stopover at an airport to refuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my recollection, during the refueling process all of the children needed to leave&#xA;   the plane. What is the reason for this procedure?&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="2407" LastEditDate="2014-12-21T19:18:11.940" LastActivityDate="2015-01-04T18:14:33.793" Title="Why do children need to leave the plane during a refueling operation?" Tags="&lt;passenger&gt;&lt;fuel&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9401" PostTypeId="1" AcceptedAnswerId="9402" CreationDate="2014-10-29T14:26:08.720" Score="28" ViewCount="6929" Body="&lt;p&gt;Can anyone identify the make and model of this aircraft? I'm just really curious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5gEFQ.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4107" LastEditorUserId="97" LastEditDate="2014-10-29T18:15:11.990" LastActivityDate="2014-10-30T03:23:39.603" Title="What is this weird plane?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9402" PostTypeId="2" ParentId="9401" CreationDate="2014-10-29T14:39:52.520" Score="25" Body="&lt;p&gt;From what I can tell, it's a Burt Rutan design. I then searched and it appears to be a &lt;a href=&quot;http://en.wikipedia.org/wiki/Rutan_Defiant&quot;&gt;Rutan Defiant&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="65" LastEditDate="2014-10-29T14:43:54.537" LastActivityDate="2014-10-29T14:43:54.537" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9403" PostTypeId="2" ParentId="9393" CreationDate="2014-10-29T15:10:28.450" Score="18" Body="&lt;p&gt;TesterMen Tester provided some very good information which I think requires a bit of explanation. The older version of the regulation seems to require fuel dump capability if MTOW is more than 105 percent of MLW. &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/faqs/arcandapproachspeeds.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;None of the 737 versions&lt;/a&gt; have weight limits under this requirement, so based on that regulation, it seems like fuel dump would be required. But as the Boeing info shows, none of the 737 versions have fuel dump capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/447579&quot; rel=&quot;nofollow noreferrer&quot;&gt;That regulation was amended in 1968&lt;/a&gt; to allow a plane to not have a fuel dump system as long as it can meet certain performance requirements. The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:1.0.1.3.11.5.185.39&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;current version of the regulation&lt;/a&gt; includes this as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this does not explain why the 737-100/200, which were certified before that amendment, don't have fuel dump capability, when the MTOW listed by the Boeing info above are 108% and 112% of the MLW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Fuel_dumping#Aircraft_fuel_dump&quot; rel=&quot;nofollow noreferrer&quot;&gt;The explanation&lt;/a&gt; is that the original versions of the aircraft had lower MTOW, which met the 105% rule. Newer engines allowed the MTOW to be increased, but as rbp mentioned, MLW is based on landing gear and structural limits, so it did not change. The FAA amended the regulation with the required performance option to allow the higher MTOW without requiring fuel dump capability. Also, as explained in answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/2854/1696&quot;&gt;this related question&lt;/a&gt;, planes can land over MLW, there just may be required inspections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the similar-sized A320 family &lt;a href=&quot;https://science.howstuffworks.com/transport/flight/modern/planes-dump-fuel-before-landing1.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;does not have fuel dump capability either&lt;/a&gt;. Smaller planes usually don't end up with the kind of fuel capacity and takeoff weights that justify a system to dump fuel.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2019-08-22T19:41:35.450" LastActivityDate="2019-08-22T19:41:35.450" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="9404" PostTypeId="2" ParentId="2186" CreationDate="2014-10-29T15:53:53.283" Score="2" Body="&lt;p&gt;This Incident is not well known so I would like to add &lt;a href=&quot;http://en.wikipedia.org/wiki/Philippine_Airlines_Flight_812&quot; rel=&quot;nofollow&quot;&gt;Philippine Airlines Flight 812&lt;/a&gt; also &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20000525-2&quot; rel=&quot;nofollow&quot;&gt;(see ASN)&lt;/a&gt; to this Question. Technically it is possible referring to this Incident.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The hijacker demanded the passengers place their valuables in a bag&#xA;  before he commanded the pilot to descend and depressurize the aircraft&#xA;  so that he could escape by a homemade parachute.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Three days after the hijacking, the hijacker was found dead, his body&#xA;  nearly buried in the mud, in the village of Llabac, in Real, Quezon,&#xA;  about 70 kilometers southeast of Manila, near the border with Laguna&#xA;  province. It is speculated that he survived the fall but was killed by&#xA;  the mud&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Edit because of constructive comment:&#xA;Of course this Incident shows that many factors like depressurizing the aircraft and low flightlevel is needed. And as kangacHASHam mentioned, the factor that you can be hit by the tail is quite high.&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-10-29T16:13:38.397" LastActivityDate="2014-10-29T16:13:38.397" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9405" PostTypeId="1" AcceptedAnswerId="9407" CreationDate="2014-10-29T16:07:15.477" Score="5" ViewCount="1240" Body="&lt;p&gt;I recently watched the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mayday_(TV_series)&quot; rel=&quot;nofollow&quot;&gt;Mayday&lt;/a&gt; series about &lt;a href=&quot;http://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054&quot; rel=&quot;nofollow&quot;&gt;TAM Airline Flight 3054&lt;/a&gt;. Landing on a short runway with only one thrust reverser in use, and the documentary explained something like:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The old Airbus procedure was to put both engines' controls on IDLE and then put only one of them on REVERSE. The new procedure says that you put both of them on REVERSE, regardless of if one of them doesn't work. The captain seemed to aim at the old procedure, &lt;strong&gt;because it is known to be more efficient&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I wonder how it is more efficient? Does the position of the controls for the second motor really influence the behaviour of the first one?&lt;/p&gt;&#xA;" OwnerUserId="802" LastEditorUserId="19" LastEditDate="2016-07-28T14:54:33.407" LastActivityDate="2016-07-28T14:54:33.407" Title="A320 procedures for one thrust reverser inoperative; why is the old procedure more efficient?" Tags="&lt;accidents&gt;&lt;engine-failure&gt;&lt;airbus-a320&gt;&lt;thrust-reverser&gt;&lt;tam3054-accident&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9406" PostTypeId="1" AcceptedAnswerId="9408" CreationDate="2014-10-29T16:29:06.937" Score="23" ViewCount="6881" Body="&lt;p&gt;In my answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/8852/is-it-possible-to-recover-dumped-fuel&quot;&gt;this question&lt;/a&gt; about fuel dumping I included the following rhetorical question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Or if you're dumping fuel from a helicopter (does that ever happen?)&#xA;  it could hover over a tank on the ground, pump out the fuel and then&#xA;  land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Two commenters said that helicopters should never need to dump fuel because if they can take off with a full fuel load then they can land again. Makes sense, but &lt;a href=&quot;http://laist.com/2010/07/23/sheriffs_department_helicopter_dump.php&quot; rel=&quot;noreferrer&quot;&gt;this news story&lt;/a&gt; refers to a helicopter dumping fuel in order to land, although it's only one article and the general (non-aviation) press is notorious for misreporting aviation incidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, can/do helicopters ever dump fuel as a safety measure before landing?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2018-06-22T18:24:40.817" Title="Do helicopters ever dump fuel before landing?" Tags="&lt;helicopter&gt;&lt;fuel-dumping&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9407" PostTypeId="2" ParentId="9405" CreationDate="2014-10-29T16:29:22.540" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Does the position of the controls for the second motor really influence the behaviour of the first one?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, it influences the activation of various other systems like the autothrust, the airbrakes, as well as the thrust reversers.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;how it is more efficient?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because in the new procedure the engine with non-functioning reverser starts to spool up before the system realizes the reverser did not deploy and cuts it again, so for a moment it produces &lt;strong&gt;forward&lt;/strong&gt; thrust. The old procedure avoids this.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="524" LastEditDate="2014-10-29T18:29:49.327" LastActivityDate="2014-10-29T18:29:49.327" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9408" PostTypeId="2" ParentId="9406" CreationDate="2014-10-29T16:44:14.883" Score="27" Body="&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/wikibase/wiki.php?id=70718&quot; rel=&quot;noreferrer&quot;&gt;Yes&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;07-NOV-1971&lt;/p&gt;&#xA;&lt;p&gt;Sikorsky CH-124A Sea King (S-61B)&lt;/p&gt;&#xA;&lt;p&gt;Suffered single engine failure on take-off. Pilot attempted to return while also dumping fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From what I've read, fuel-dump systems are more common on military helicopters.&lt;/p&gt;&#xA;&lt;p&gt;Sometimes, a helicopter may not have enough power to hover in ground effect for a normal landing or take-off because of loss of an engine, high density altitude, or being overweight. The alternative procedure is to perform a &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch10.pdf&quot; rel=&quot;noreferrer&quot;&gt;running take-off or running landing&lt;/a&gt;, which is an advanced, but not an emergency, maneuver.&lt;/p&gt;&#xA;&lt;p&gt;But if the copter is landing in a confined area, such as a small pad on a frigate in a stormy ocean, there's no room for a running landing, so its better to dump fuel to allow the copter to hover into a landing.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-04T16:40:29.243" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9409" PostTypeId="1" AcceptedAnswerId="9413" CreationDate="2014-10-29T17:14:45.993" Score="18" ViewCount="15645" Body="&lt;p&gt;The Airbus A380 has a maximum take-off weight of almost 600 tons. How strong does the joint between the wings and the fuselage have to be so it doesn't break? And how could it be trusted unless real-time fractures don't occur? How was it tested? I mean, you cannot accomodate such a big joint in a wind tunnel except in computer simulations.&lt;/p&gt;&#xA;" OwnerUserId="4111" LastEditorUserId="2627" LastEditDate="2014-10-30T14:57:02.813" LastActivityDate="2018-04-03T16:18:28.360" Title="How strong is the A380 fuselage-wing joint?" Tags="&lt;aircraft-design&gt;&lt;flight-testing&gt;&lt;airbus-a380&gt;&lt;fuselage&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9410" PostTypeId="2" ParentId="9406" CreationDate="2014-10-29T17:42:24.500" Score="15" Body="&lt;p&gt;Helicopters can take off when too heavy to hover, either by moving forward while in ground effect or by reducing the pitch of the anti-torque rotor to get a bit more power into the main rotor (there's a book called Chickenhawk by Robert Mason which describes using both of these processes on Hueys in Vietnam - not a bad read IMO). It's risky to use either of these methods in the first place, but there's added risk as landing overweight is so dangerous. So in helicopters which may have to take off overweight being able to dump fuel is a good safety feature. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-10-29T17:42:24.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9411" PostTypeId="1" AcceptedAnswerId="9417" CreationDate="2014-10-29T19:35:08.730" Score="13" ViewCount="17696" Body="&lt;p&gt;I saw a few videos of the Sukhoi Su-35 doing some amazing aerobatics and I was wondering if a civilian could ever fly one - either for aerobatics or just fly it as their personal jet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously assume adequate training, fitness, budget, time etc. I assume you'll have to start on a jet trainer first, after you had already flown other smaller aircraft - but this is outside the scope of my question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is &lt;a href=&quot;https://aviation.stackexchange.com/questions/9311/civilians-buying-military-aircraft&quot;&gt;a question&lt;/a&gt; that suggests civilians can buy military aircraft, but it doesn't explicitly say whether they can actually fly them. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9311/civilians-buying-military-aircraft#comment17369_9311&quot;&gt;One comment seems to suggest they can't&lt;/a&gt;, although it's not very clear.&lt;/p&gt;&#xA;" OwnerUserId="3221" LastEditorUserId="97" LastEditDate="2014-10-29T20:00:27.913" LastActivityDate="2015-03-01T03:37:35.347" Title="Can civilians fly military aircraft?" Tags="&lt;military&gt;&lt;pilots&gt;&lt;aerobatics&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9412" PostTypeId="1" AcceptedAnswerId="9414" CreationDate="2014-10-29T19:53:00.073" Score="21" ViewCount="9028" Body="&lt;p&gt;RAF Typhoons were scrambled today to intercept an Antonov 26 that lost comms, &lt;a href=&quot;http://www.itv.com/news/london/2014-10-29/raf-fighter-jets-scrambled-to-intercept-an-airliner-trigger-sonic-boom-over-london-and-kent/&quot; rel=&quot;noreferrer&quot;&gt;triggering a sonic boom&lt;/a&gt; over London.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight was escorted to Stansted airport, and the answer at &lt;a href=&quot;https://aviation.stackexchange.com/questions/7922/whats-the-point-in-escorting-a-threatened-flight-with-two-fighter-jets&quot;&gt;What&amp;#39;s the point in escorting a threatened flight with two fighter jets?&lt;/a&gt;&#xA; says they &quot;guide&quot; the rogue jet to the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do they actually do this? Once they've established the jet is not a threat, how do they communicate with the other pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have an image in my head of them writing &lt;code&gt;← 120°&lt;/code&gt; (etc.) on a little whiteboard :P&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="1696" LastEditDate="2018-04-27T14:18:01.680" LastActivityDate="2018-04-27T14:18:01.680" Title="How do fighter jets communicate with an intercepted plane that's lost comms?" Tags="&lt;radio-communications&gt;&lt;fighter&gt;&lt;jet&gt;&lt;flight-interception&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9413" PostTypeId="2" ParentId="9409" CreationDate="2014-10-29T20:07:37.553" Score="20" Body="&lt;p&gt;The details of the strength required are likely to be complicated and proprietary. However, we can do a very rough estimate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the equation for estimating root bending moment &lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-01-unified-engineering-i-ii-iii-iv-fall-2005-spring-2006/systems-labs-06/spl10.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, and the following numbers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuselage weight: 230,000 kg&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;MTOW: 577,000 kg&lt;/li&gt;&#xA;&lt;li&gt;Engines: &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent#Trent_900&quot; rel=&quot;nofollow noreferrer&quot;&gt;25,000 kg&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Fuel: 260,000 kg&lt;/li&gt;&#xA;&lt;li&gt;Wings: 60,000 kg&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Wingspan: 79.75 m&lt;/li&gt;&#xA;&lt;li&gt;Wing taper ratio: &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/A380Dean.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.17&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The equation gives a root bending moment of 17,300,000 Nm. Of course, this is just a static load. If you consider a 2.5 g pullup, this could be 43,300,000 Nm. But on the ground, the wings will bend under their own weight. Running the bending equation on the wing weight, and adding in the engines, gives 23,900,000 Nm in the other direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to how it can be trusted: a &lt;strong&gt;lot&lt;/strong&gt; of math. Organizations like EASA expect way more accuracy than my above estimate, which requires analysis of the specific loading conditions that need to be met, both static and dynamic, and the specific design of the wing, structurally and aerodynamically, which is how aerospace engineers earn the big bucks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the A380 is bigger than anything mass-produced before. But the in-depth analysis will take this into account. Airbus has some experience building large aircraft, so they have a pretty good idea of what works and what doesn't. Detailed testing is also done, on everything from the nuts and bolts up to &lt;a href=&quot;https://aviation.stackexchange.com/a/9415/1696&quot;&gt;entire airframes&lt;/a&gt;. All of this information is used to back up the design. Airbus isn't going to invest money in a large test without being reasonably sure it will work, and EASA isn't going to certify a design until it has been successfully tested. Modern analysis allows predicting pretty accurately where and at what load structure will fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even then, with something so large and complex, things happen. Important things like the wings are required to not fail even if they are damaged, and to have redundant load paths so that even if a part fails, the remaining structure will hold. Parts are inspected to look for damage before it becomes critical. &lt;a href=&quot;http://aviationweek.com/blog/easa-extends-a380-wing-crack-airworthiness-directive&quot; rel=&quot;nofollow noreferrer&quot;&gt;Problems are found&lt;/a&gt;. More analysis is done, and fixes are implemented. Usually this won't be an issue of &quot;the wing can't handle the load&quot;, but that &quot;the wing wears out too quickly&quot;. &lt;a href=&quot;https://aviation.stackexchange.com/a/9418/1696&quot;&gt;Fatigue&lt;/a&gt; is harder to predict and design for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requirements are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.11#se14.1.25_1301&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR Part 25&lt;/a&gt;. This includes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So they must take the maximum load expected without permanent deformation (limit load), and allow a 1.5 safety factor on top of that without failing (ultimate load). In order to show that the structure is capable of meeting the requirements:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Compliance with the strength and deformation requirements of this subpart must be shown for each critical loading condition. Structural analysis may be used only if the structure conforms to that for which experience has shown this method to be reliable. The Administrator may require ultimate load tests in cases where limit load tests may be inadequate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that all analysis has to be shown to be reliable. This must either be tested, or compared to the known performance of previous designs. The testing must also be sufficient to prove the requirements will be met.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-10-30T14:46:57.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9414" PostTypeId="2" ParentId="9412" CreationDate="2014-10-29T20:26:47.740" Score="30" Body="&lt;p&gt;This is covered in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html&quot;&gt;FAA's AIM, Chapter 5, Section 6&lt;/a&gt;. The UK has &lt;a href=&quot;http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Flight%20Ops%20-%20Interception%20Procedures%20Signals%20Aerad.pdf&quot;&gt;similar&lt;/a&gt; &lt;a href=&quot;http://www.caa.co.uk/docs/33/20130121SSL11.pdf&quot;&gt;procedures&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the standard guard frequency is 121.5 or 243.0 MHz. If you aren't listening to this frequency and get intercepted, you should start listening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Methods like LED signs or possibly as whiteboard as you suggested can also be used. Otherwise, they maneuver their aircraft to send standard signals. See the guides above for details on the signals sent by interceptors and how they should be acknowledged. Basically:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You have been intercepted, follow me&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Interceptor: Rocks wings (and flashes lights irregularly at night)&lt;/li&gt;&#xA;&lt;li&gt;Intercepted: Same&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You may proceed&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Interceptor: Breakaway, climbing turn away from aircraft&lt;/li&gt;&#xA;&lt;li&gt;Intercepted: Rocking wings&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Land here&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Interceptor: Circling airport, lowering landing gear, overflying runway (landing lights on at night)&lt;/li&gt;&#xA;&lt;li&gt;Intercepted: Lower gear, land&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The intercepted aircraft can also send signals. The interceptor will respond with one of the signals above.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Designated airport is inadequate&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Intercepted: Raise gear, flash landing lights&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Cannot comply&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Intercepted: Switching on and off all lights, but distinct from flashing lights&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In distress&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Intercepted: Irregular flashing of all lights&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the case of the Washington, DC Special Flight Rules Area (DC SFRA), there is a Visual Warning System (VWS) of red and green lights that will let the pilot know that they shouldn't be there. The pilot is supposed to turn directly away from the center of the SFRA. If they are in contact with ATC they must advise that they have been illuminated by the system, otherwise they should contact ATC on a guard frequency and identify themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, an interceptor can't &lt;em&gt;force&lt;/em&gt; an intercepted aircraft follow instructions. It goes on to explain what will happen if you don't follow those rules, which probably apply in any situation where the risk is too high:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Further noncompliance with interceptor aircraft or ATC may result in the use of force. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-10-30T14:55:32.217" LastActivityDate="2014-10-30T14:55:32.217" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9415" PostTypeId="2" ParentId="9409" CreationDate="2014-10-29T20:27:56.323" Score="35" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;how could it be trusted?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Like all aircraft, type certification requires that these be tested. I think the wings are tested to 1.5 x their load limit.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/company/aircraft-manufacture/how-is-an-aircraft-built/test-programme-and-certification/&quot; rel=&quot;noreferrer&quot;&gt;A380: STRUCTURAL STATIC TESTS&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The A380’s structural static tests on began in November 2004, in preparation for the first flight clearance.&lt;/p&gt;&#xA;&lt;p&gt;The tests included: Flight Test Installation (FTI) calibration test, &lt;strong&gt;maximum wing bending at limit load&lt;/strong&gt;, ailerons and spoilers functioning test during max wing bend, fuselage pressure test, and fatigue tests and flight cycles simulation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;They place an airframe into a &lt;a href=&quot;http://www.youtube.com/watch?v=Q9ins-nbsGY&quot; rel=&quot;noreferrer&quot;&gt;test rig&lt;/a&gt; and increase the load on the wings until the wings break. The empirical evidence is compared with the predictions made by mathematical models.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/A3UPt.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;Airbus A380 wing test&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WGsbY.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;Airbus A350 wing test&lt;/em&gt; ... (&lt;a href=&quot;http://videos.airbus.com/video/5ad221220dcs.html&quot; rel=&quot;noreferrer&quot;&gt;A350 torture video&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o2BMz.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;Boeing 787 wing test&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-10-29T21:20:15.723" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9416" PostTypeId="2" ParentId="9412" CreationDate="2014-10-29T20:50:20.243" Score="7" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html#JhCd2ROBE&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM section 6&lt;/a&gt; describes what the pilot in the intercepted plane should do:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First thing the intercepting craft will do is rock the wings irregularly (and flash the nav lights at night) and initiate a turn (usually on the left). The intercepted aircraft should copy that and follow. That signals that an intercept has taken place and the other plane is compliant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If time is of the essence then the fighter can do a climbing turn in front of the other aircraft in the direction it should turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the escort is at an end (and allows the craft to fly on) then the fighter will break away with a 90° turn, the response is to wiggle the wings again and continue on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To signal the intercepted plane to land the fighter will circle the airport and do a flyover over the runway with lowered gear (imitating a go-around). The other plane may do a flyover to make sure it's clear to land and then go land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the intercepted pilot believes he can't land on the runway he should stow his gear and flash his landing lights during the flyover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible the intercepting plane will hand over control to the tower and let it use the &lt;a href=&quot;https://aviation.stackexchange.com/a/3798/609&quot;&gt;light gun&lt;/a&gt; to guide it down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If at any point the pilot cannot comply he should switch on and off his lights at a regular interval. If the intercepted pilot is in distress then he should flash all available lights&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-10-29T20:50:20.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9417" PostTypeId="2" ParentId="9411" CreationDate="2014-10-29T21:35:57.923" Score="17" Body="&lt;p&gt;I'm not sure if you're asking about &lt;em&gt;flying&lt;/em&gt; such an aircraft (e.g. renting one) or &lt;em&gt;owning&lt;/em&gt; one. But either way the answer is yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've flown a &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Hunter&quot;&gt;Hawker Hunter&lt;/a&gt; at a (now-defunct) location in Cape Town on a mixed low-level/acrobatic flight along the coast. There were no restrictions on who could fly in the aircraft apart from the obvious ones (no kids; must have reasonable height/weight and general fitness) but they didn't let non-pilots take the controls. We did some aerobatics (up to 5G, from memory) and I had the controls in cruise flight for about 10 minutes. There was absolutely nothing that a civilian couldn't learn: it's 'just' another aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for owning one, it's not uncommon at all. Privately owned ex-military aircraft are often referred to as &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Warbird&quot;&gt;warbirds&lt;/a&gt;&quot; and in the US there's even an &lt;a href=&quot;http://www.warbirds-eaa.org/&quot;&gt;EAA organization&lt;/a&gt; for owners. The aircraft are usually considered experimental (or the local equivalent) for the purposes of regulation and airworthiness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The barriers to owning these aircraft are (as always) money and training. Buying and maintaining them is very expensive because there are so few parts or mechanics available, and insuring them is (almost) impossible so most owners have to self-insure. The operating costs are also usually high, especially if the aircraft systems need 'exotic' fuels, gases, lubricants or other consumables. You may need to include explosives on the list, in the case of ejection seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Training is a similar issue because so few people can instruct you in how to fly a military aircraft, but obviously this isn't a total barrier and I assume that if you're involved in that part of the flying community then you'll find the contacts you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in general, if you can buy a military aircraft legally in your country, if you have enough money for operations and maintenance, if you can find someone to train you, and if you can comply with your local regulations on non-type (experimental) aircraft then you can absolutely do it. But for most people that's a lot of 'ifs' :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-10-29T21:35:57.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9418" PostTypeId="2" ParentId="9409" CreationDate="2014-10-29T21:49:40.150" Score="30" Body="&lt;p&gt;The ugly truth is: Cracks do occur, and have occurred on the A380 wing root, but that is normal. Read on for more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The static load is only one aspect. Normally, what is driving the design is the fatigue load, which is the constant jerking of aerodynamic and inertial forces on all parts of an airplane. Today, aircraft are designed such that cracks will not become threatening between two inspection intervals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This technique was learnt &lt;a href=&quot;http://www.afgrow.net/applications/DTDHandbook/pdfs%5CSec1_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;the hard way with the aircraft of the late Forties and early Fifties&lt;/a&gt;. Up until then, the operational life of metal aircraft was in the order of tens of hours. Parts were designed for the maximum static load plus a safety factor of 1.5 to 2.0. Fatigue was not considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wooden aircraft have no fatigue problems, however, aluminum is extremely sensitive to cyclic loading. Cracks will appear after enough load cycles even at very low stress levels, and will grow with any additional load cycle. Now the approach is to define inspection intervals such that cracks which start right after the last inspection will not grow to a point which threatens structural integrity before the next inspection is scheduled. To ensure this, all major parts need to be made of two load-carrying members, one of which could fail without causing the whole part to fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we have established that each part of the fuselage-wing joint is made of two parallel members, each of which is able to carry the full limit load for which the part has to be designed. We also know that this strength can only be guaranteed for a part of the aircraft's life. In case of the A380, two things combine to make the wing root design a particular challenge. The first is scaling laws: If something grows in size, its volume and mass will grow with the cube of the size increase, but the cross section of the load-carrying structure will only grow with the square of the increase. The second factor is the high cruise Mach number of 0.85 of the A380. This had been demanded to make sure that flights with the A380 will not take more time than flights with any competing airliner, so that A380 flights are always on the first screen of the booking systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high cruise Mach number demands a thin wing airfoil, and the scaling laws mean that an A380 will need relatively thicker flanges and fittings than a smaller aircraft. This can be computed with high accuracy with finite element codes like &lt;a href=&quot;http://www.mscsoftware.com/product/patran&quot; rel=&quot;noreferrer&quot;&gt;Patran&lt;/a&gt; in combination with &lt;a href=&quot;http://en.wikipedia.org/wiki/Nastran&quot; rel=&quot;noreferrer&quot;&gt;NASTRAN&lt;/a&gt;, or &lt;a href=&quot;http://en.wikipedia.org/wiki/Ansys&quot; rel=&quot;noreferrer&quot;&gt;ANSYS&lt;/a&gt;. After the computational design, one wing has to be loaded until it breaks in a test rig, and another wing will be subjected to simulated flight stresses in another test rig. Here the gust loading is important, which cannot be simulated in a wind tunnel. Therefore, the wing is loaded by an array of hydraulic jacks which are computer-controlled to simulate aerodynamic loads. When &lt;a href=&quot;http://www.hbm.com/en/menu/applications/test-measurement/case-studies/airbus/&quot; rel=&quot;noreferrer&quot;&gt;enough testing&lt;/a&gt; has been done, the aircraft will be certified for an initial number of flight hours which will be gradually increased as the dynamic test progresses. In case of the A380, some &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2109150/Wing-cracks-A380-superjumbos-sparked-global-recall-blamed-British-engineering-firm.html&quot; rel=&quot;noreferrer&quot;&gt;early aircraft showed cracks&lt;/a&gt; at the wing root, so local reinforcements were added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the ugly truth is that cracks do occur regularly, but the structural design and the operating procedures ensure that they do not cause massive failures.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-19T03:25:44.467" LastActivityDate="2015-04-19T03:25:44.467" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9419" PostTypeId="2" ParentId="9406" CreationDate="2014-10-30T01:17:21.450" Score="2" Body="&lt;p&gt;As one of the original commenters I suppose I'm as good as any to reply here!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't remember my wording off the top of my head, but essentially I pointed out that if a helicopter has the power to lift off at a certain weight, or hover/climb, it is by definition capable of slowly descending and therefore landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike an airliner which has to essentially 'fly' onto the runway, straining the landing gear, a helicopter does not. In theory, one can land with virtually no extra force other than the weight of the heliopter. In practice this isn't quite true, but you get the idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in reality that doesn't mean a helicopter will never dump fuel (or want to) - in an emergency situation it makes sense to reduce weight to improve responsiveness, and if I'm about to crash I'd like as little highly flammable liquid around as possible!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also a small number of (mainly military) helicopters which do generate lift when moving, therefore can takeoff at a higher weight than they can hover... In these cases they are more akin to fixed wing aircraft in terms of having to 'fly' onto the ground rather than performing a vertical landing, and therefore may need to reduce weight to reduce stress,&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-10-30T01:17:21.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9420" PostTypeId="2" ParentId="9411" CreationDate="2014-10-30T02:02:41.347" Score="6" Body="&lt;p&gt;I have flown an L-39 military trainer that a local FBO was renting time in.  Lots of fun, but not something you want to fly any distance.    &lt;a href=&quot;http://www.jetwarbird.com/training1.html&quot; rel=&quot;noreferrer&quot;&gt;This place&lt;/a&gt; will give you an orientation ride and work with you on getting your LOA if you are interested in buying and flying a jet warbird. There also was an outfit in one of the former Soviet countries that would give your rides in more modern Migs like the Mig-29. &lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-10-30T02:02:41.347" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9422" PostTypeId="2" ParentId="9406" CreationDate="2014-10-30T05:50:01.590" Score="13" Body="&lt;p&gt;I have never crewed on a helicopter that dumps fuel, nor have I known of any machine in the fleet that even has that capability - though I have been wrong before.&lt;/p&gt;&#xA;&lt;p&gt;It has been noted already that helos can take off and land at max Gross Take Off Weight (GTOW), or all up weight (AUW) and thus do not require weight shedding to land safely (as we don't have wings to store fuel so we don't have to worry about over-stressing them on landing). However, keep this in mind: different fuel loads alter the emergency course of action in the case of a forced landing.&lt;/p&gt;&#xA;&lt;p&gt;When considering helicopter performance (and we will talk in terms of torque), we explore 2 main ideas - &lt;strong&gt;power required&lt;/strong&gt; and &lt;strong&gt;power available&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;h2&gt;Power Required&lt;/h2&gt;&#xA;&lt;p&gt;Power required is the amount of torque that I need on the main rotor to overcome gravity and get into hover flight. Hover flight is always the most power hungry because i'm drawing air down into the rotor in order to create the smooth fast airflow over the blades and then pushing it down to the ground. There are two modes of hover flight - Hover in ground effect (HIGE) and hover out of ground effect (HOGE).&lt;/p&gt;&#xA;&lt;h3&gt;Hover In Ground Effect&lt;/h3&gt;&#xA;&lt;p&gt;Hover in ground effect is where you are close enough to the ground (around 4 feet) that you draw the air down through the rotor disk and it pushes in into the ground. In accordance with Newton's Third Law, as the downwash pushed into the ground, it also pushes back towards the rotor, creating a high pressure &amp;quot;bubble&amp;quot; beneath the helo, and reduces the recirculating air on the rotor tips.&lt;/p&gt;&#xA;&lt;h3&gt;Hover Out of Ground Effect&lt;/h3&gt;&#xA;&lt;p&gt;Hover out of ground effect is where we are roughly over a rotor span in the air - say around 50 feet. We have now lost that cushion of air beneath us because there is no air trapped between us and the ground. It simply recirculates around and around.&lt;/p&gt;&#xA;&lt;p&gt;Sometimes a picture is worth a 1000 words:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/I04QH.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;As I hover in ground effect, I get a bit of help because I have that bubble helping keep me in the air, meaning my rotor has to do less work (really its less AOA or pitch pulled from my collective), whereas I don't have that help out of ground effect. The difference (at least for the bell 412) is around 11 percent torque. This means at a given take off weight, I will require 11 percent less torque in ground effect than out of ground effect to maintain hover flight.&lt;/p&gt;&#xA;&lt;p&gt;Getting back to power required, this is the torque needed to lift the sum of all the weight on board my helo (and the helo itself). This means the more cargo + more fat bodies + more gas in the tanks = more power required. This is going to affect my HIGE and HOGE torques, along with my minimum safe airspeed (which i'll cover later).&lt;/p&gt;&#xA;&lt;h2&gt;Power Available&lt;/h2&gt;&#xA;&lt;p&gt;Power available is the second half - this is what the engines and rotor can produce in terms of power and thrust/lift. The 2 main factors are altitude and temperature. We measure these in terms of torque as well - mast torque for the rotor and engine torque for the motors - but for now we are only going to focus on mast torque. Essentially, this is the amount of final drive power we have in our pocket. Air is power - so the more air we have, the more torque we produce. Cold air at sea level in the Arctic will produce more power than hot air in the mountains of Afghanistan - see density altitude if you want to learn more. For a given altitude and temp, I will be able to produce a certain amount of power measured by rotor torque percent. A cold day I could get 100% mast torque. A hot day I might only get 85% mast torque because I've run out of engine turbine temp to produce power or I've run out of collective pitch because my rotor blades are at max pitch. Most helicopters are also multi-engine, so two engines running will get me 100% torque, where if I lose an engine I might only get 60% mast torque.&lt;/p&gt;&#xA;&lt;p&gt;Finally  there is a safe minimum airspeed for single engine operations (there is the deadman curve for twin engine, but we are talking emergencies here). As a helo hovers, it draws air down from above to create the airflow over the blades - essentially the spinning of the rotor is solely responsible for creating relative wind. As we start to translate into forward flight, airflow is established over the blades by forward movement, creating a relative wind more in line with the blade chord. Our forward flight means the helicopter depends less on pure blade rotation to create air movement for lift because forward flight is providing the clean relative wind over the blades. This lets us stay in the air with less torque required.&lt;/p&gt;&#xA;&lt;p&gt;If you made it this far, great!&lt;/p&gt;&#xA;&lt;h2&gt;Example&lt;/h2&gt;&#xA;&lt;p&gt;So how does this tie all together? Lets use an example:&lt;/p&gt;&#xA;&lt;p&gt;All up weight: 11,500 lbs.&#xA;Fuel on board: 2000 lbs.&#xA;Mast torque available (twin engine): 100%.&#xA;Mast torque available (one engine inoperative - 2.5 minute power): 65%.&#xA;Mast torque available (one engine inoperative - continuous power): 54%.&#xA;Minimum airspeed (single engine): 25 kts.&#xA;Hover torque required (in ground effect) 75%.&#xA;Hover torque required (out of ground effect) 86%.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Helicopters landing at or near maximum all up weight is normally limited to a factor of power required/available rather than a factor of airframe loading limits/overstressing&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;h3&gt;Scenario #1&lt;/h3&gt;&#xA;&lt;p&gt;You are in ground effect hover and lose an engine. You pull the collective into your armpit and accept settling with power because your power available single engine (65%) cannot meet the power required (HIGE 75%). Fuel dumping is not an issue here.&lt;/p&gt;&#xA;&lt;h3&gt;Scenario #2&lt;/h3&gt;&#xA;&lt;p&gt;You are out of ground effect hover and lose an engine. Again, you pull the collective into your armpit and accept significant settling with power because - you guessed it - power available single engine (65%) cannot meet the power required (HOGE 86%) and you accelerate to the earth. The whole iteration takes about 5-7 seconds, and the result lands you as a flaming fireball on the 6 oclock news - however you don't get to see it. This is why you don't hover heavy OGE, and why you don't violate your deadmans curve! No time for fuel dumping, so not an issue here.&lt;/p&gt;&#xA;&lt;h3&gt;Scenario #3&lt;/h3&gt;&#xA;&lt;p&gt;You are in a high hover (HOGE) - say 150 feet. You lose an engine, but instead of pulling the collective into your armpit and dying, you pull some power and push the cyclic forward - accelerating above safe single engine speed (25 kts). You start to arrest your descent as you trade altitude for airspeed, bringing enough speed in to climb out safely. You can then either choose to stay in the air on single engine for the next hour to burn enough fuel to facilitate a HIGE landing, or you can carry out a run-on landing at or above 25 kts at your current weight. No fuel dumping required.&lt;/p&gt;&#xA;&lt;h3&gt;Scenario #4&lt;/h3&gt;&#xA;&lt;p&gt;You do a no-hover (or rolling) takeoff and climb out above minimum safe single engine speed (25 kts), and then lose an engine. You have two options - continue the climb out and burn some gas until you bring your all up weight down to a torque that will allow you to hover single engine 2.5 minutes (which will take at least an hour - thats why flight engineers bring ipads and magazines), or simply continue your circuit and carry out a run on landing (or rolling landing) at or above 25 kts. Nice, slow, not a lot of runway needed. Fuel dumping not an issue. Keep in mind that a nice slow decent with loaded blades is key - every approach is an approach to overshoot with the option to land.&lt;/p&gt;&#xA;&lt;h2&gt;Summary&lt;/h2&gt;&#xA;&lt;p&gt;Remember, the fuel loads in most helicopters - even the big ones - are measured in thousands of lbs and not tens of thousands of lbs. We don't carry a significant amount of gas to really alter our landing profile - all we need is enough to stay in the air for a couple of hours. After that, our backs, necks and egos are sore from terrain flight and vibrations.&lt;/p&gt;&#xA;&lt;p&gt;As an extra note, trying to dump fuel in the hover would be a hazardous mistake. As you dump fuel mist, it would recirculate through the rotorwash back onto the helo - into the engines and all over the place in general. Then after it lights off, your land as soon as practical emergency just turned into a one bell alarm. IF it were to happen, you would need an established minimum airspeed to carry it out, but then you certainly wouldn't be transferring it to a ground storage tank.&lt;/p&gt;&#xA;" OwnerUserId="3787" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-06-22T18:24:40.817" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9423" PostTypeId="2" ParentId="2827" CreationDate="2014-10-30T07:27:52.487" Score="4" Body="&lt;p&gt;For serial number 31-35&#xA; - Pilot seems to be Brookley, Wendell H &#xA; - Homebase seems to have been Wright Field, Dayton, OH &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationarchaeology.com/src/1940sB4/1934.htm&quot; rel=&quot;nofollow&quot;&gt;See Link&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For serial number 31-85&#xA; - Pilot seems to be Larkin, James D.&#xA; - Homebase seems to have been Boeing Field, Seattle, WA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationarchaeology.com/src/dbahb.asp?HB=boeing&amp;amp;offset=-1&quot; rel=&quot;nofollow&quot;&gt;See Link&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationarchaeology.com/src/reports.htm&quot; rel=&quot;nofollow&quot;&gt;It seems that you can order any of these Reports.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-10-30T07:35:36.467" LastActivityDate="2014-10-30T07:35:36.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9424" PostTypeId="2" ParentId="9236" CreationDate="2014-10-30T08:38:39.917" Score="1" Body="&lt;p&gt;In the early days of A380 only prototypes were available, flying from airshow to airshow, each time with a livery of national company of the place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They used giant adhesive films from &lt;a href=&quot;http://www.self-adhesive-film.com/&quot; rel=&quot;nofollow&quot;&gt;Adhetec&lt;/a&gt; (&lt;a href=&quot;http://www.solutions-adhesives.fr/documents/mo_edito_img/1325000283_11_1.pdf&quot; rel=&quot;nofollow&quot;&gt;13880 film series&lt;/a&gt;(pdf)).&lt;/p&gt;&#xA;" OwnerUserId="4119" LastActivityDate="2014-10-30T08:38:39.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9425" PostTypeId="1" CreationDate="2014-10-30T09:16:43.200" Score="6" ViewCount="1951" Body="&lt;p&gt;I have a question related to this &lt;a href=&quot;https://aviation.stackexchange.com/questions/3312/how-often-does-fan-blade-out-happen&quot;&gt;question&lt;/a&gt; and &lt;a href=&quot;https://www.youtube.com/watch?v=JQ0NU6I6Qt4&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;. The question says that sometimes a fan blade failure can occur. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;My question now is, if a fan blade separates or a malfunction occurs, is the engine still repairable? &lt;/li&gt;&#xA;&lt;li&gt;I think the damage to the engine's structure would be quite high?&lt;/li&gt;&#xA;&lt;li&gt;According to the video a fan blade malfunction occurred on start-up, how could a malfunction appear on start-up?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2018-04-22T18:43:12.350" Title="Is engine damage due to a fan blade failure irreparable?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9426" PostTypeId="2" ParentId="9425" CreationDate="2014-10-30T10:28:12.990" Score="7" Body="&lt;p&gt;This depends on the failure: A fan blade can be damaged by birds, debris, or aircraft parts (pitot probe for example).  In this case the blades are dented, in which case it is possible to replace the damaged parts, inspect the engine and re-use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this kind of damage it has to be disassembled and inspected by the engine manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inspection of blades is done with a microscope: For example, I have seen an HPT blade declared unserviceable because of a small scratch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously if the repair costs more than a new engine you don't repair the old one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many more things can happen in startup:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engine is run on full power&lt;/li&gt;&#xA;&lt;li&gt;There is a lot of possible interactions (like birds for example) that you don't have in a steady cruise at 40,000 feet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aside from debris, you can also have &lt;a href=&quot;https://www.youtube.com/watch?v=RopA50BDqsc&quot; rel=&quot;nofollow noreferrer&quot;&gt;a compressor stall like this&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="11671" LastEditDate="2018-04-22T18:40:46.103" LastActivityDate="2018-04-22T18:40:46.103" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9427" PostTypeId="1" CreationDate="2014-10-30T14:36:50.137" Score="4" ViewCount="1576" Body="&lt;p&gt;Now I've heard that passenger airliners do not generally have airbrakes , and simply use their spoilers as airbrakes since they can perform the same function. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any major jets that use speedbrakes (by major I mean widely used by countries or airlines, and it must be a passenger jet)&lt;/p&gt;&#xA;" OwnerUserId="4122" LastEditorUserId="22726" LastEditDate="2019-02-27T23:08:02.093" LastActivityDate="2019-02-27T23:08:02.093" Title="Do major passenger airline jets have airbrakes/speedbrakes?" Tags="&lt;flight-controls&gt;&lt;airbrakes&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9428" PostTypeId="2" ParentId="9427" CreationDate="2014-10-30T14:40:23.327" Score="12" Body="&lt;p&gt;Yes (for some values of major)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_brake_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rb0px.jpg&quot; alt=&quot;BAE 146&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Adrian Pingstone&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/KLM-Cityhopper/Fokker-70-(F-28-0070)/0503269/L/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GJdNT.jpg&quot; alt=&quot;Fokker 70&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;(c) Harm Rutten&lt;/em&gt;&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-10-30T14:46:37.777" LastActivityDate="2014-10-30T14:46:37.777" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9429" PostTypeId="2" ParentId="9425" CreationDate="2014-10-30T15:20:35.030" Score="4" Body="&lt;p&gt;Jet engines are fairly expensive, accounting for a large part of the cost of an airliner. So there will be some incentive to repair the engine if possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether an engine is repairable is dependent on the failure. If it happens at startup and mostly causes a bunch of smoke, like in the linked video, then the damage may be fairly limited and will probably be repaired. If damage is suspected, a borescope inspection is generally done to check the inner parts of the engine for damage as well. If a failure happens at &lt;a href=&quot;http://www.youtube.com/watch?v=wcALjMJbAvU&quot; rel=&quot;nofollow noreferrer&quot;&gt;full thrust&lt;/a&gt;, the engine is probably finished. Aircraft and engines are designed for this failure, but a full blade failure will cause extensive damage. Parts that get loose and enter the engine core will cause further damage through the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, serious failures are generally investigated, especially if they are considered &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbine_engine_failure#Notable_uncontained_engine_failure_incidents&quot; rel=&quot;nofollow noreferrer&quot;&gt;uncontained&lt;/a&gt;. This will mean at least extensive downtime for the engine, and may or may not end up being repaired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many malfunctions that can occur at &lt;a href=&quot;https://aviation.stackexchange.com/questions/1959/how-are-turbine-engines-started&quot;&gt;startup&lt;/a&gt;. The engine has been shut down for some period of time, during which:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Parts cool down and contract&lt;/li&gt;&#xA;&lt;li&gt;Debris can enter the engine&lt;/li&gt;&#xA;&lt;li&gt;Things can leak or get damaged&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Whatever has changed will be discovered when the engine is started. Also, the problem in the video seemed to only appear after taxiing for some distance, so the engine could have ingested FOD at some point. It's not clear whether the 10 minute hold is due to ATC or the pilots noticing abnormal engine parameters.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-10-30T15:20:35.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9430" PostTypeId="2" ParentId="8259" CreationDate="2014-10-30T17:12:57.153" Score="14" Body="&lt;p&gt;Generally the planes are scrapped by a &lt;a href=&quot;http://recycling.about.com/od/Recycling/a/Airplane-Recycling-An-Up-And-Coming-Industry.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;recycling company&lt;/a&gt;. The parts will either be removed and sold as spares, or chopped up and recycled or disposed of. So a lot will depend on how easy it is to remove the part, and how much of a market there is for it. Airplanes are disassembled to a large extent during heavy checks, which can provide an opportunity for substituting in spares.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Engines:&lt;/strong&gt; Probably the most valuable part of the airplane. These will be removed and either used as whole spares or for spare parts, depending on the condition and how many of the type are still in service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cockpit instruments:&lt;/strong&gt; These will be removed and used as spares as well, if there is enough of a market (everyone wants those &lt;a href=&quot;http://www.rockwellcollins.com/sitecore/content/Data/News/2014_Cal_Year/CS/FY14CSNR44-767LDS.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;fancy glass cockpits&lt;/a&gt; these days).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Interiors:&lt;/strong&gt; These may be removed as well, they can be used as spares.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Control surfaces:&lt;/strong&gt; These can be removed and used as spares as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Windows:&lt;/strong&gt; These can be removed and reused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Systems:&lt;/strong&gt; Pumps, electronics, lights, actuators, etc.: Most of these can be removed and sold as spares.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Landing gear:&lt;/strong&gt; This can also be removed and reused, depending on the number of cycles it already has.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tires:&lt;/strong&gt; The tires may be reused if not worn out. The &lt;a href=&quot;http://www.desser.com/epdf/Good_Year_Aviation_Tire_Care.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;tubes&lt;/a&gt; may not be reused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airframe:&lt;/strong&gt; Although some parts may be able to be used, generally the effort and the fact that there are probably many cycles on the part will prevent much from being used as-is. The metal will be chopped up as scrap. They are already working on recycling major &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/environment/pdf/recycling.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;composite structure&lt;/a&gt; as well, since manufacturing scrap is already being created. &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_08/article_02_4.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Boeing&lt;/a&gt;, with modern recycling processes, the metal, plastic, wires/electronics, and carbon fiber composites are used for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;15% High-grade industrial&lt;/li&gt;&#xA;&lt;li&gt;50% Low-grade industrial&lt;/li&gt;&#xA;&lt;li&gt;35% Landfill&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As it often is with business charts, it's not clear if these are by weight, volume, or what. &lt;a href=&quot;http://www.tarmacaerosave.aero/index.php?option=com_content&amp;amp;view=article&amp;amp;id=18&amp;amp;Itemid=123&amp;amp;lang=en&quot; rel=&quot;nofollow noreferrer&quot;&gt;This company&lt;/a&gt; claims to recycle 90% of the weight of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are of course cases like &lt;a href=&quot;https://aviation.stackexchange.com/a/8286/1696&quot;&gt;Steve V. mentions&lt;/a&gt; where the plane is donated to some institution, but this doesn't happen to most planes. There are also ways that airplane parts find &lt;a href=&quot;http://www.pinterest.com/aviationhd/aircraft-recycled-into-furniture/&quot; rel=&quot;nofollow noreferrer&quot;&gt;other uses&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-10-30T17:12:57.153" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9432" PostTypeId="1" AcceptedAnswerId="9433" CreationDate="2014-10-31T11:33:40.923" Score="16" ViewCount="8207" Body="&lt;p&gt;I have a question about the 707 Engine Inlet Doors, according to &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; the Pratt &amp;amp; Whitney JT3D inlet doors purpose is to provide additional air. Is the thrust higher on more air intake? And why modern engines don't have it anymore?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5dnsg.png&quot; alt=&quot;Intake&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="19" LastEditDate="2016-11-01T11:56:29.460" LastActivityDate="2018-07-11T21:16:52.027" Title="What is the purpose of the inlet doors of the Pratt &amp; Whitney JT3D?" Tags="&lt;jet-engine&gt;&lt;boeing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9433" PostTypeId="2" ParentId="9432" CreationDate="2014-10-31T13:45:55.257" Score="21" Body="&lt;p&gt;The intake speed at the compressor is between Mach 0.4 and Mach 0.5 and changes little with airspeed. That means that at low speed the intake has to suck in air from a wide capture area, (even from behind the inlet lip at low speed) while at high speed only the part that flows into the center of the intake is digested, while surrounding air will spill over the intake lip and flow around the nacelle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The surface that separates the flow going into the engine and that which does not is called the stagnation stream line or surface. This surface is way aft of the inlet lip at low speed, and the pressure near it is the highest (stagnation pressure). The challenge for the inlet designer is to design the lip with a rounded shape so that the flow going into the engine is uniform. It won't be if the lip is as shaped in the sketch. The high pressure on the outside and the low pressure inside the lip open the doors to admit a small percentage of the air to the engine inlet at low speed. As airplane speed increases, the stagnation point (or line) shifts to the lip itself and the pressure equalizes on the doors, closing them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ycwO8.png&quot; alt=&quot;intake flow&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fairly sharp intake lip of the JT3D will capture air rather inefficiently at low speeds (the topmost case in the sketch above), which could even lead to flow separation right after the intake lip, reducing mass flow and compressor efficiency. By adding the suction-activated doors, the intake can capture more air and keep the flow attached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More recent intake designs have thicker intake lips, so the flow stays attached even at very low airspeed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-07-11T21:16:52.027" LastActivityDate="2018-07-11T21:16:52.027" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="9434" PostTypeId="1" AcceptedAnswerId="9435" CreationDate="2014-10-31T18:20:10.343" Score="17" ViewCount="8339" Body="&lt;p&gt;At a large airport (think &lt;a href=&quot;http://en.wikipedia.org/wiki/London_Heathrow_Airport&quot;&gt;Heathrow&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/John_F._Kennedy_International_Airport&quot;&gt;JFK&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/O%27Hare_International_Airport&quot;&gt;O'Hare&lt;/a&gt;), I would imagine that the runways take a lot of abuse from all the huge planes landing on them.  So, a quick multipart question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How do large passenger planes damage runways?  Does it differ depending on the surface?&lt;/li&gt;&#xA;&lt;li&gt;How long can a runway sustain this damage before the runway must be repaired or resurfaced?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Keep in mind, I'm talking about normal wear and tear.  So, I'm not really wondering how long it takes to repair a runway after a 767 lands with it's gear up, for example.  Rather just wondering how the normal maintenance cycle works.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="62" LastEditDate="2014-10-31T19:18:51.450" LastActivityDate="2014-11-07T09:40:45.637" Title="How often do runways need to have typical maintenance?" Tags="&lt;airport&gt;&lt;runways&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9435" PostTypeId="2" ParentId="9434" CreationDate="2014-10-31T20:31:48.510" Score="17" Body="&lt;p&gt;The pavement requires frequent renewal of the top surface. The frequency depends on the type of pavement and on the weather. Asphalt for instance suffers a lot of damage when it snows and becomes less viscous when it is very hot, &lt;a href=&quot;http://www.washingtonpost.com/local/crime/plane-gets-stuck-at-reagan-national/2012/07/08/gJQAZgG9UW_story.html&quot;&gt;causing heavy aircraft to sink&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main issue with repairing a runway on a major airport like JFK or O'Hare is doing so with little to no impact on traffic. Resurfacing an entire runway can take a long time. Therefore, rather than closing the runway for days at a time, airports try to do as many short maintenance operations as possible at night.&#xA;Some operations cannot be done in a single night but can be divided into several perfectly timed tasks, that can be done between 11 PM and 5 AM. Some operations can not be divided into such small tasks and require that the airport closes for a day or more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The French airport Orly (ORY) for instance has one slab of concrete replaced every night on the runway. This way, the strip can be renewed every other year on average, without disturbing traffic. (I saw a video on this subject once, but can't seem to find it again.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The results of each runway inspection are compared with the results of the previous runway inspection. Maintenance programs are revised based on the rate of deterioration of the runway. The FAA has &lt;a href=&quot;http://www.faa.gov/airports/central/airport_compliance/pavement_maintenance/&quot;&gt;various resources&lt;/a&gt; to help airport operators plan these maintenance operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But damage done by huge planes is only one of the many things that needs to be taken care of on a regular basis. Moreover, aircraft manufacturers try to design landing gear that reduces the impact of the aircraft on the runway as much as possible (note that airports can charge higher landing fees for aircraft that do more damage to the runway, so airlines want airplanes that don't damage the runway).&#xA;The most common maintenance operations are (not in any order, and indicated frequencies are only a rule of thumb, as these will change from one airport to another):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Removing rubber. This is an important one. When taking off or landing, aircraft often skid for a brief moment and leave rubber on the runway. This greatly reduces the adherence of the runway, which has a negative impact on stopping distances. This is usually done with high pressure water.&lt;/li&gt;&#xA;&lt;li&gt;Cleaning the approach light systems and other visual aids. These get dirty with rubber, tartar, dirt... This operation can be done for instance with a mix of water and sodium bicarbonate, or &lt;a href=&quot;http://www.lepoint.fr/societe/la-nuit-l-aeroport-de-roissy-nettoie-ses-feux-de-piste-avec-de-la-glace-21-08-2010-1227318_23.php&quot;&gt;by using dry ice&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;li&gt;Checking the quality of the approach light systems and other visual aids. Often, a truck with optometric sensors drives down the runway and measures the luminosity. Sometimes the lights need to be replaced. Airports usually have spares available for every type of light that is used on the runway.&lt;/li&gt;&#xA;&lt;li&gt;Paint and markings somtimes have to be redone. &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5320_6e.pdf&quot;&gt;Evaluating the pavement and surveying the structural condition of the runway&lt;/a&gt;. Trucks are equipped with all kinds of sensors and go up and down the runway. The measures are used to make a map of the condition of the runway. Sometimes, the runway is divided into sub-sections and a different section will be evaluated every month or every other month, so that each section is inspected twice a year. &lt;/li&gt;&#xA;&lt;li&gt;Checking for foreign objects on the runway. On all the airports I visited, this is done by the airport firetruck several times a day. Every few months, they sweep the runway to prevent grass, dirt, pebbles,... from accumulating. &lt;/li&gt;&#xA;&lt;li&gt;Repairing cracks and resealing joints on the runway. This is to prevent water infiltrations that have long-term catastrophic consequences. A visual inspection of the runway is performed daily to look for cracks.&lt;/li&gt;&#xA;&lt;li&gt;Cutting the grass around the runway and on the airfield. The grass has to be kept 2 to 4 inches high around the runway. This reduces the amount of debris that can be blown onto the runway. This also reduces the number of birds and other animals living close to the runway (because nobody wants birds to be ingested by an engine, or a squirrel to be run over). &lt;/li&gt;&#xA;&lt;li&gt;Keeping all water evacuation paths clear. No water can be left to build up on the runway, since this would increase stopping distance for aircraft, and may freeze. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There also are seasonal operations, such as de-icing the runway or removing snow.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2014-11-01T00:13:00.207" LastActivityDate="2014-11-01T00:13:00.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9436" PostTypeId="1" AcceptedAnswerId="9439" CreationDate="2014-10-31T20:55:22.473" Score="8" ViewCount="10589" Body="&lt;p&gt;One of the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/9434/how-often-do-runways-need-to-have-typical-maintenance&quot;&gt;this question&lt;/a&gt; mentions how runways are usually in need of de-icing on cold days (which makes sense), and as anyone who has ridden an airplane on a cold day knows, planes need de-icing too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm wondering is a few things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is used to de-ice a commercial aircraft?&lt;/li&gt;&#xA;&lt;li&gt;What is used to de-ice a runway at a large airport?&lt;/li&gt;&#xA;&lt;li&gt;Do the two fluids effect each other at all?  Meaning, when an aircraft drips de-icing fluid onto the runway, does it cause any interactions or problems?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-21T14:30:31.620" Title="What do they use to de-ice aircraft and runways on snowy days?" Tags="&lt;airport&gt;&lt;ground-operations&gt;&lt;anti-ice&gt;&lt;cold-weather&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9437" PostTypeId="2" ParentId="9411" CreationDate="2014-10-31T20:57:40.153" Score="4" Body="&lt;p&gt;The test pilots of military aircraft manufacturers are also civilians flying military aircraft. They perform among others checkout flights before delivery or after repair of every single military aircraft. Usually they are former military pilots.&lt;/p&gt;&#xA;" OwnerUserId="3964" LastActivityDate="2014-10-31T20:57:40.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9438" PostTypeId="2" ParentId="9436" CreationDate="2014-10-31T21:31:32.510" Score="0" Body="&lt;p&gt;They test whether the runway needs clearing with a vehicle with acceleration sensors to check the grip when the driver steps on the brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports will try to avoid using salt or glycol to clear the runway for environmental and maintenance reasons (salted sludge spray will corrode exposed metal on the plane) though they can be very effective for keeping the runway clear in moderate temperatures. Preferring the mechanical plows, blowers and sweepers to clear the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports also use grit to provide a grippy surface for the plane.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-10-31T22:03:45.223" LastActivityDate="2014-10-31T22:03:45.223" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9439" PostTypeId="2" ParentId="9436" CreationDate="2014-10-31T21:34:58.843" Score="6" Body="&lt;p&gt;&lt;strong&gt;What is used to de-ice a commercial aircraft?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Deicing_fluid&quot; rel=&quot;nofollow noreferrer&quot;&gt;De-icing fluids&lt;/a&gt; are used which are made of &lt;a href=&quot;http://en.wikipedia.org/wiki/Ethylene_glycol&quot; rel=&quot;nofollow noreferrer&quot;&gt;ethylene glycol (EG)&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Propylene_glycol&quot; rel=&quot;nofollow noreferrer&quot;&gt;propylene glycol (PG)&lt;/a&gt; in addition to other ingredients.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gMvZh.jpg&quot; alt=&quot;Airplane Deicing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is used to de-ice a runway at a large airport?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports use different types of materials, e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Potassium_acetate&quot; rel=&quot;nofollow noreferrer&quot;&gt;potassium acetate&lt;/a&gt;. &lt;a href=&quot;http://www.runway-deicer.com/pages/safegrip-eco2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Safegrip ECO2&lt;/a&gt; is a brand which is popular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/De-ice#Approaches&quot; rel=&quot;nofollow noreferrer&quot;&gt;Runways can also be deiced&lt;/a&gt; using normal techniques like salt and snowplows etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do the two fluids effect each other at all? Meaning, when an aircraft drips de-icing fluid onto the runway, does it cause any interactions or problems?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;I do not think that there is much or any damage to a runway from the de-icing fluid. If something is bad for solid concrete, how it can be good for fragile aluminium?&lt;/strike&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Research shows that the residuals left on the airplanes cause some issues. Those are described below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Effect of runway de-icing fluid residuals on airplanes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some studies that show the runway fluid having some adverse effects when combined with de-icing fluid residuals on airplanes. &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_1_07/article_03_2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;They state&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Runway deicing fluids contain potassium acetateor potassium&#xA;  formate-based fluids (deionizing salts). When these fluids combine,&#xA;  the separation of the anti-icing fluid thickeners may be enhanced,&#xA;  leading to a more rapid formation of the residue.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Effect of airplane de-icing fluid residuals on airplanes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, de-icing fluid residuals on airplanes can freeze and cause damages to flight controls. More information is &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_1_07/article_03_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k9KER.jpg&quot; alt=&quot;Boeing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-09-21T14:30:31.620" LastActivityDate="2015-09-21T14:30:31.620" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9440" PostTypeId="1" AcceptedAnswerId="9444" CreationDate="2014-10-31T22:49:06.757" Score="7" ViewCount="22933" Body="&lt;p&gt;The description of PlanePlotter claims that it can determine the registration letters from the ICAO 24 bit address algorithmically for some countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing i got so far is how to get the country. Any clues?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some more research I found some information in the book &quot;Principles of Avionics&quot; by Albert Helfrick: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Generally, there is no algorithm giving a one-to-one correspondence&#xA;  between ICAO 24 bit addresses and the registration number of the&#xA;  aircraft. Some ICAO member states did have an algorithm that would&#xA;  translate ICAO 24 bit aircraft addresses to registration numbers but&#xA;  ICAO strongly suggested the practice to stop.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Algorithm for swedish registrations: &lt;a href=&quot;http://www.transportstyrelsen.se/publicdocuments/PDF165.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.transportstyrelsen.se/publicdocuments/PDF165.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4133" LastEditorUserId="13197" LastEditDate="2016-04-25T10:31:43.607" LastActivityDate="2018-07-07T23:26:05.327" Title="How to get registration from ICAO 24 bit code?" Tags="&lt;icao&gt;&lt;aircraft-registration&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9441" PostTypeId="1" CreationDate="2014-10-31T23:30:09.337" Score="9" ViewCount="2534" Body="&lt;p&gt;I need some help identifying a LEGO plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The LEGO set &lt;a href=&quot;http://brickset.com/sets/7292-1/Propeller-Adventures&quot; rel=&quot;nofollow noreferrer&quot;&gt;7292&lt;/a&gt;, &lt;em&gt;Propeller Adventures&lt;/em&gt;, features a twin engine airplane, with conventional landing gear, and a bubble canopy.  There are no pontoons on the wings&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming it's based on a real plane, does anyone have any ideas?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UsgHg.png&quot; alt=&quot;7292 Propeller Adventures&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4094" LastEditorUserId="-1" LastEditDate="2017-02-21T03:36:08.490" LastActivityDate="2017-02-21T03:36:08.490" Title="Help Identifying a LEGO plane" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="10" ClosedDate="2014-11-01T23:49:40.383" ContentLicense="CC BY-SA 3.0" />
  <row Id="9442" PostTypeId="2" ParentId="9441" CreationDate="2014-10-31T23:33:10.150" Score="5" Body="&lt;p&gt;There are a few which are similar on some points, although all have at least one issue. In the end I suspect in the end it's just a &quot;generic mid-wing, twin engined WWII fast bomber&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the radial engines, it looks a lot like a de Havilland Mosquito&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FNp1w.jpg&quot; alt=&quot;de Havilland Mosquito&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or perhaps a Junkers Ju88&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1oldp.jpg&quot; alt=&quot;Junkers Ju88&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or a CAC Woomera, at a stretch&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hx5WL.jpg&quot; alt=&quot;CAC Woomera&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2014-10-31T23:52:03.407" LastActivityDate="2014-10-31T23:52:03.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9443" PostTypeId="2" ParentId="9441" CreationDate="2014-10-31T23:45:06.930" Score="3" Body="&lt;p&gt;Could also be a Ki-45&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eU6oA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or except for the tail a BR-20&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lLUBX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-10-31T23:45:06.930" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9444" PostTypeId="2" ParentId="9440" CreationDate="2014-11-01T04:06:49.860" Score="4" Body="&lt;p&gt;Apparently (according to &lt;a href=&quot;http://www.gatwickaviationsociety.org.uk/modeslookup.asp&quot; rel=&quot;nofollow&quot;&gt;these folks&lt;/a&gt;) some countries use an algorithm to generate their ICAO (Mode S) 24-bit IDs. For those countries, you can simply reverse the algorithm and get a registration given the Mode S ID.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Others countries allow you to download their registration database, complete with the Mode S identifier (&lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/releasable_aircraft_download/&quot; rel=&quot;nofollow&quot;&gt;you can get the US registration database here&lt;/a&gt;) - it's a simple matter to load this into your own software and map the ICAO/Mode S ID code to a registration number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the folks at Gatwick Aviation Society have noted, some countries are tight-lipped about how their codes are assigned (and who they're assigned to), so these lookups are probably not complete.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-01T04:06:49.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9445" PostTypeId="2" ParentId="5018" CreationDate="2014-11-01T12:50:53.997" Score="25" Body="&lt;p&gt;Flaps change the camber of the wing's airfoil. This in turn changes the zero-lift angle of attack, increases the maximum lift potential and, in case of fowler-type flaps, the wing's area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners use flaps on both take-off and landing, and most of the time they are only partly deflected. Full deflection is only set on final approach to reduce the landing speed as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When simple camber flaps are used, the drag increase is negligible for small deflections (±10° for a 20% flap), and they can be used for both take-off and landing. Other types of flaps are designed to increase drag (split flap, Zap flap) and should be used only for landing. If flight speed stays constant, a flap deflection will only change induced drag if it redistributes lift over the wingspan. Modern gliders use camber flaps inboard and flaperons (a combination of aileron and flap) outboard, and changing flap settings will not affect induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the purpose of flaps is to shift the minimum airfoil drag to the desired lift coefficient &lt;span class=&quot;math-container&quot;&gt;$c_L$&lt;/span&gt;. Especially laminar airfoils have a pronounced range of lift coefficients with low drag. The pilot should attempt to stay within this region of minimum drag, and flaps give him/her the means to achieve this. See below for an example of an airfoil at a Reynolds number of 1 Mio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h3WS3.png&quot; alt=&quot;flap polar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps for lift increase work the same way, but change camber much more. Normally, they need to be combined with leading edge devices (slats) which change camber at the airfoil's nose to unfold their full potential. Below are some examples for flaps, in combination with proper leading edge devices. Note that the solid outline of the fowler flap is the position for landing, while the dashed outline is the position for take-off. &lt;span class=&quot;math-container&quot;&gt;$\delta$&lt;/span&gt; is the relative chord of the flap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bva4E.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Junkers flaps were the best way to control &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_G.38&quot; rel=&quot;noreferrer&quot;&gt;big&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_52&quot; rel=&quot;noreferrer&quot;&gt;aircraft&lt;/a&gt; in the days before more elaborate force compensation mechanisms were developed, and split- and Zap flaps were very popular in the 1930s. They are still used on smaller aircraft today. The simple Fowler flap is used on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;noreferrer&quot;&gt;C-130&lt;/a&gt;, and airliners use slotted flaps like the ones in the lowest two rows of the table above. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides increasing drag, powerful flaps change the pitching moment of the wing by shifting the center of lift backwards, which requires sufficient tail size and control power. On airliners, the incidence of the full horizontal tail can be adjusted in order to create enough downforce to counteract the pitching moment. Note on the picture of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-70&quot; rel=&quot;noreferrer&quot;&gt;An-70&lt;/a&gt; below that the stabilizer has a slat which operates in the opposite direction to that of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Tsntt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tsntt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2019-03-02T01:17:11.317" LastActivityDate="2019-03-02T01:17:11.317" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="9446" PostTypeId="1" CreationDate="2014-11-01T23:50:11.250" Score="12" ViewCount="4261" Body="&lt;p&gt;What is the oldest aircraft still in production? I Googled it but only got the answer to the oldest military aircraft still in production.&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="13197" LastEditDate="2016-05-06T20:23:39.797" LastActivityDate="2016-07-17T07:48:30.537" Title="What is the oldest aircraft still in production?" Tags="&lt;aviation-history&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9447" PostTypeId="2" ParentId="9446" CreationDate="2014-11-02T00:36:25.983" Score="2" Body="&lt;p&gt;A gander on the list of most &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_most-produced_aircraft&quot; rel=&quot;nofollow&quot;&gt;produced aircraft on Wikipedia&lt;/a&gt; suggests the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;Cessna 172&lt;/a&gt; which started production in 1956 and is still produced today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeronca_Champion&quot; rel=&quot;nofollow&quot;&gt;Aeronca Model 7 Champion&lt;/a&gt; has returned to production in 2007 after a short production run from 1945-1950.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="97" LastEditDate="2014-11-02T00:54:37.803" LastActivityDate="2014-11-02T00:54:37.803" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9448" PostTypeId="2" ParentId="8900" CreationDate="2014-11-02T01:16:19.177" Score="7" Body="&lt;p&gt;A Boeing 757's just been &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2816032/Plane-forced-return-Gatwick-escape-slide-fell-off.html&quot; rel=&quot;noreferrer&quot;&gt;in the news&lt;/a&gt;, flight &lt;a href=&quot;http://aviation-safety.net/wikibase/wiki.php?id=170754&quot; rel=&quot;noreferrer&quot;&gt;TCX1638&lt;/a&gt; from London Gatwick to Hurghada Egypt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly after takeoff its emergency escape slide, as well as the unit it was housed in, fell off the jet!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WfvfL.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above photo is of the 4 meter / 13 feet long chute housing that detached. Luckily it landed in a field; I can only imagine the potential for damage it could've had!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/permalink.php?story_fbid=666495463448707&amp;amp;id=449916508439938&quot; rel=&quot;noreferrer&quot;&gt;Kent Police stated&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft part that police have been looking for is said to be an overwing emergency slide unit (similar to the one pictured) that is believed to house one of the evacuation chutes that deploy in an emergency after a plane has landed. The uninflated chute is believed to have been trailing from the unit as it fell to the ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AAIB has launched an investigation.&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2014-11-02T01:16:19.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9449" PostTypeId="2" ParentId="8900" CreationDate="2014-11-02T03:31:02.643" Score="6" Body="&lt;p&gt;One major issue that must be kept in mind is the sheer lack of probability that something falling from the sky would ever hit somebody.  As a relatable example, it is estimated that over &lt;a href=&quot;http://www.psi.edu/epo/faq/meteor.html&quot; rel=&quot;noreferrer&quot;&gt;500 meteorites actually strike the surface of the earth every year&lt;/a&gt;, the vast majority of which never hit anyone or anything of value.  The reason is that there is a looooooot of unused space on this planet of ours, space between continents, major cities, even houses inside of said city.  (Also keep in mind that &lt;a href=&quot;http://www.sfgate.com/bayarea/article/Mythbusters-cannonball-hits-Dublin-home-minivan-2353937.php&quot; rel=&quot;noreferrer&quot;&gt;even if a large object hits a house,&lt;/a&gt; no matter the origin, that doesn't mean that anyone in the house will be hurt.  Living quarters also have a lot of empty space in them.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, keep in mind, there have been &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;a lot&lt;/a&gt; &lt;a href=&quot;https://www.youtube.com/watch?v=_VyHa05LyIA&quot; rel=&quot;noreferrer&quot;&gt;of cases of&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Korean_Air_Flight_801&quot; rel=&quot;noreferrer&quot;&gt;entire planes&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Arrow_Air_Flight_1285&quot; rel=&quot;noreferrer&quot;&gt;falling out of the sky&lt;/a&gt; and for the most part nobody is hurt except (sadly, though inevitably) the people on the plane.  This can even be true when it's &lt;a href=&quot;http://en.wikipedia.org/wiki/TWA_Flight_800&quot; rel=&quot;noreferrer&quot;&gt;near a populated center&lt;/a&gt;.  Because there is a lot of empty space even near big cities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, yes, I would agree with the other answers that being hit in the head with a piece of junk from an aircraft would be dangerous, probably deadly.  But I would contest that the chances of it actually happening are extraordinarily small.  Not impossibly, but very very small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, to actually answer your question: &lt;em&gt;I'd say that the vast majority of the time an object falling off of a plane isn't dangerous at all.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2014-11-02T03:31:02.643" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9450" PostTypeId="1" AcceptedAnswerId="9451" CreationDate="2014-11-02T08:15:12.903" Score="7" ViewCount="2703" Body="&lt;p&gt;Is the vertical tail the primary reason for causing landings to be skewed in a crosswind? Please explain the effect of the fuselage, the tail, or other components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the vertical stabilizer is the primary reason for crosswind landings, do flying wings with no vertical tails (say, the B-2) experience this issue?&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="287" LastEditDate="2015-05-16T15:01:14.587" LastActivityDate="2017-08-03T21:04:00.173" Title="How do flying wings respond to crosswinds?" Tags="&lt;landing&gt;&lt;crosswind&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9451" PostTypeId="2" ParentId="9450" CreationDate="2014-11-02T10:43:08.030" Score="8" Body="&lt;p&gt;Short answer: The reason for &lt;a href=&quot;https://aviation.stackexchange.com/questions/1262/what-is-the-difference-between-a-crabbed-and-de-crab-landing&quot;&gt;crabbing&lt;/a&gt; (skewed flight, as you call it) during an approach in crosswind is to keep the wings level while maintaining sideslip-free flight. Flying wings are not fundamentally different, because they, too, have stability characteristics similar to those of conventional aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes want to be flown without sideslip. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292#9292&quot;&gt;Flying in a sideslip&lt;/a&gt; (where a component of the airspeed comes from one side) incurs lots of complications:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some of the lift is also pointing sideways, so the airplane drifts sideways.&lt;/li&gt;&#xA;&lt;li&gt;Weathervane stability will make the aircraft yaw into the wind. This comes mainly from the vertical tail, but is only one of many components to make the aircraft controllable.&lt;/li&gt;&#xA;&lt;li&gt;The dihedral effect will cause a rolling moment, lifting the windward wing.&lt;/li&gt;&#xA;&lt;li&gt;Wing sweep will increase this rolling moment and add more yawing moment.&lt;/li&gt;&#xA;&lt;li&gt;Since the vertical tail sits upward of the line of symmetry in most airplanes, this also adds to the rolling moment.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most of these effects are desired, because they make the aircraft easier to fly, but during approach they make it harder to line it up with the runway. If the fuselage is held parallel to the runway, the windward wing needs to be lowered, so some of the lift points sideways into the wind, compensating the side force caused by sideslipping. This is achieved by keeping the ailerons deflected to work against the aforementioned effects, and the rudder needs to keep the airplane from turning into the wind. This is no problem as long as the airplane is high enough. On touchdown, however, such an attitude cannot be maintained, or the aircraft will hit the ground with a part of the wing or an engine nacelle first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only by pointing the fuselage into the wind can the course of the airplane be aligned with the runway in a sideslip-free way. This is called crabbing, because when seen from the ground the aircraft's speed has a lateral component, a little like a crab wich is also known for its sideways movement. Now the wings are level, so the touchdown will happen with the wheels first. Unfortunately, now the wheels' rotation direction is not aligned with the runway, and to reduce wear, pilots kick the rudder just before touching the ground to re-orient the aircraft parallel to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed C-5&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-52&lt;/a&gt; can rotate their gear struts, which enables both aircraft to touch down in crabbed flight. All other types produce more tire smoke and jerk the aircraft sideways if they touch down this way.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-11-02T13:55:49.590" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9452" PostTypeId="2" ParentId="9450" CreationDate="2014-11-02T14:05:34.817" Score="4" Body="&lt;p&gt;The vertical tail is &lt;strong&gt;NOT&lt;/strong&gt; the reason for &quot;skewing&quot; (I assume you mean crabbing) in crosswind landings. The answer is &lt;strong&gt;directional stability&lt;/strong&gt;. But first, let's take a look at why crosswind landings are a problem.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aircrafts fly relative to the air&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Aircrafts fly in the air. They fly in a way such that the air pressure is balanced around the aircraft. Thus, if there is a 100 knot perfectly steady wind, any aircraft would fly just fine. A ground observer would see a 100 knot difference in the aircraft's velocity vector, but the relative movement between the aircraft and its surrounding air is exactly the same as a no-wind condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try moving around a train. The train is travelling at 50 mph, yet you can move around the cabin just like on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if some pilot is going to land, he must transition from travelling through air to travelling on the ground. That's when the problem arises. His ground track must be along the centerline of the runway, and he must be pointing in the same direction as his ground track as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to the train analogy, try jumping from a 50 mph train to the ground. It's difficult because you have to match the 2 movements: one relative to the train and another relative to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we understand that aircrafts move through steady wind just as they do in still air. If a crosswind is 20 knots from the right, the B2 would be drifting to the left at 20 knots if its heading is exactly the same as the runway.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Directional stability&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Let's assume what you said is true: on a B2 (which has no vertical tail), the aircraft is not affected by crosswind, and thus can land by pointing the nose straight at the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then it logically follows, that a crosswind of &lt;em&gt;any&lt;/em&gt; magnitude would have an neglectable effect on the aircraft. Which also means, if the aircraft starts floating left or right, there is no way the pilot can control it! He can hold winds level and a constant heading (say 360), but the aircraft may drift sideways!&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-11-02T14:05:34.817" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9453" PostTypeId="2" ParentId="9446" CreationDate="2014-11-02T19:57:41.950" Score="4" Body="&lt;p&gt;I don't know if it counts, but the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot; rel=&quot;nofollow&quot;&gt;Messerschmitt Me-262&lt;/a&gt; has seen a &lt;a href=&quot;http://www.stormbirds.com/project/index.html&quot; rel=&quot;nofollow&quot;&gt;second production run&lt;/a&gt; of five aircraft being finished earlier this century after approx. 1500 had been built before the middle of the last, from 1941 - 1945. The new production was started in 1993 by the Texas Aircraft Factory, led by someone who had learned metal aircraft craftsmanship as an apprentice in Germany during WW II and who later moved to the US. The job was finished in Seattle by ex-Boeing people, and the aircraft were rivet-for-rivet copies from the original design, with one exception: They are powered by &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_J85&quot; rel=&quot;nofollow&quot;&gt;J-85&lt;/a&gt; engines instead of the old &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_004&quot; rel=&quot;nofollow&quot;&gt;Junkers 004B&lt;/a&gt;. The Junkers jets were similar in size and mass to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;nofollow&quot;&gt;EJ 200&lt;/a&gt; of the Eurofighter, but with 1/7 of the thrust and just 50 hours between overhauls were considered a liability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Already in 1950, in the early phase of the Korean war, a new series of the Me-262 was briefly considered when US aircraft found themselves to be outclassed by &lt;a href=&quot;http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15&quot; rel=&quot;nofollow&quot;&gt;Soviet-built jets&lt;/a&gt;. In the end, the Me-262 wing design heavily influenced that of the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-86_Sabre&quot; rel=&quot;nofollow&quot;&gt;North American F-86 Sabre&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-11-02T19:57:41.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9454" PostTypeId="1" AcceptedAnswerId="9467" CreationDate="2014-11-03T03:54:33.947" Score="24" ViewCount="8155" Body="&lt;p&gt;Why don't small airplanes (like Cessna or Cirrus) have &quot;Check Engine&quot; lights, like cars do?  For the most part, the people flying these airplanes don't know much more about the plane than they do their car.  Wouldn't a &quot;Check Engine&quot; light be useful to many people flying these planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or do the rigorous maintenance schedules required for airplanes invalidate any use that a &quot;Check Engine&quot; light would have? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="-1" LastEditDate="2014-11-04T00:27:44.033" LastActivityDate="2019-02-14T13:02:55.903" Title="Why isn't there a &quot;check engine&quot; light in airplanes?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="9" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9455" PostTypeId="2" ParentId="9454" CreationDate="2014-11-03T04:37:34.120" Score="45" Body="&lt;p&gt;Because your basic premise is completely wrong.  The people flying a Cessna or Cirrus generally have a vast amount more knowledge about their planes than the average car owner.  Between the POH (Pilot Operating Handbook) and the general systems information that is part of every level of curriculum that level of knowledge of your average GA pilot is vastly greater than your average driver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add to it that indications need to be specific in airplanes.  A pilot needs to know what failed in and what way so they can make an appropriate decision.  Their lives depend on it, unlike in a car.&lt;/p&gt;&#xA;" OwnerUserId="3516" LastActivityDate="2014-11-03T04:37:34.120" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9456" PostTypeId="1" AcceptedAnswerId="9457" CreationDate="2014-11-03T12:10:37.167" Score="7" ViewCount="15216" Body="&lt;p&gt;This question came up after reading the following comments on the answer to this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1189/raising-the-flaps-right-after-touchdown-good-or-bad&quot;&gt;Raising the flaps right after touchdown. Good or bad?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1189/raising-the-flaps-right-after-touchdown-good-or-bad?rq=1#comment1819_1190&quot;&gt;Philippe Leybaert Jan 20 at 23:00&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The retractable landing gear is an excellent point. It makes perfect&#xA;  sense. I've read a few stories of pilots retracting the gear after&#xA;  landing instead of raising the flaps.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1189/raising-the-flaps-right-after-touchdown-good-or-bad?rq=1#comment1821_1190&quot;&gt;voretaq7♦ Jan 20 at 23:02&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The retractable landing gear issue is particularly notable because&#xA;  early in the landing roll you may not have enough weight on the wheels&#xA;  to activate the squat switch that prevents you from retracting your&#xA;  gear while you're using them to hold the plane up. Your perfect&#xA;  landing could turn into a nice, smooth gear-up incident if you bump&#xA;  the wrong switch.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does the squat switch work (which prevent gear up on the ground)?&lt;/li&gt;&#xA;&lt;li&gt;Are there any reports on issues of gear up on ground? &lt;a href=&quot;http://www.torch.aetc.af.mil/news/story.asp?id=123113372&quot; rel=&quot;nofollow noreferrer&quot;&gt;(I only know&#xA;one&lt;/a&gt;)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2018-03-21T02:29:00.857" Title="How does the squat switch work?" Tags="&lt;landing-gear&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9457" PostTypeId="2" ParentId="9456" CreationDate="2014-11-03T12:31:17.507" Score="10" Body="&lt;p&gt;The squat switch is essentially a sensor that senses if the weight of the aircraft is resting on the gear. This can be done by &lt;a href=&quot;http://en.wikipedia.org/wiki/Load_cell&quot; rel=&quot;noreferrer&quot;&gt;load cell&lt;/a&gt; or displacement sensor on the suspension arm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like any other component these sensors can fail though engineers prefer them to fail in an always on (weight on the gear) state; that way the pilot just needs to deal with gear failing to retract after takeoff and needing to land again to check it out rather than dropping the plane on the ground and causing more damage.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-11-05T18:10:26.810" LastActivityDate="2014-11-05T18:10:26.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9458" PostTypeId="2" ParentId="9454" CreationDate="2014-11-03T13:11:47.173" Score="10" Body="&lt;p&gt;Generally, the vigorous maintenance and checks on aircraft mean that a light is superfluous - you'll have checked things fairly recently anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you're already in the air and your engine develops a problem, you likely don't need a light to inform you....nor would one particularly help you out, unless the bulb is particularly good at engine-out landings. &lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-11-03T13:11:47.173" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9460" PostTypeId="2" ParentId="9454" CreationDate="2014-11-03T14:54:44.063" Score="23" Body="&lt;p&gt;First, consider what a check engine light &lt;a href=&quot;http://lifehacker.com/5878754/the-five-most-common-check-engine-problems-and-what-you-should-do-about-them&quot;&gt;actually&lt;/a&gt; &lt;a href=&quot;http://www.bankrate.com/finance/auto/top-10-check-engine-light-car-repairs-1.aspx&quot;&gt;tells&lt;/a&gt; &lt;a href=&quot;http://auto.howstuffworks.com/under-the-hood/diagnosing-car-problems/mechanical/check-engine-light.htm&quot;&gt;you&lt;/a&gt;. In short, it could be almost anything, which isn't very useful information. To find out what the specific problem is, you need to go to a garage and have a mechanic run a diagnostic check to determine what triggered the light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a car, that's no big deal, but in an aircraft that's a huge problem: imagine that you're flying above cloud at night with potential icing below you and the light comes on (for this discussion, let's leave aside the wisdom of putting yourself in that position in the first place). In the absence of other information, what action do you take? Is it serious enough that you need to get on the ground ASAP and risk the descent through freezing conditions? Or is it reasonable to continue to your destination? Or compromise and look for an alternate that's clear of cloud but not on the way to your destination? The only way to make an informed decision is to have as much specific information as possible, and a single 'something's wrong' light doesn't give you that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, I don't know if your question is deliberately provocative but I question the assumption that light aircraft pilots don't know much about their aircraft systems. Your profile says that you hold a private pilot's license and are in the USA, and the USA FAA's &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot;&gt;Practical Test Standards&lt;/a&gt; require the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Task G: Operation of Systems (ASEL and ASES)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;References: FAA-H-8083-23, FAA-H-8083-25; POH/AFM.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Objective: To determine that the applicant exhibits satisfactory &#xA;  knowledge of the elements related to the operation of  systems on the&#xA;  airplane provided for the flight test by  explaining at least three of&#xA;  the following systems:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Primary flight controls and trim.&lt;/li&gt;&#xA;  &lt;li&gt;Flaps, leading edge devices, and spoilers.&lt;/li&gt;&#xA;  &lt;li&gt;Water rudders (ASES).&lt;/li&gt;&#xA;  &lt;li&gt;Powerplant and propeller.&lt;/li&gt;&#xA;  &lt;li&gt;Landing gear.&lt;/li&gt;&#xA;  &lt;li&gt;Fuel, oil, and hydraulic.&lt;/li&gt;&#xA;  &lt;li&gt;Electrical.&lt;/li&gt;&#xA;  &lt;li&gt;Avionics.&lt;/li&gt;&#xA;  &lt;li&gt;Pitot-static, vacuum/pressure and associated flight  instruments.&lt;/li&gt;&#xA;  &lt;li&gt;Environmental.&lt;/li&gt;&#xA;  &lt;li&gt;Deicing and anti-icing.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course some pilots will cram for their test and then forget a lot of this information, but in general I think it's pretty difficult to get a pilot's license without having a good working knowledge of aircraft systems. Speaking personally, I know a whole lot more about the systems in the aircraft that I fly than I do about the ones in the car I drive (in part because the equivalent instrumentation and information simply aren't available to me in the car).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, maintenance is essential but by itself it doesn't reduce the need for the pilot to understand what's going on. It's commonly said by pilots that it's important to fly the aircraft conservatively for the first few hours after a major service and if you do have some kind of failure in that time then you should suspect it's related to the maintenance. Maintenance can only reduce failures, not prevent them completely, and when something does go wrong then you still need as much information as possible.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="1931" LastEditDate="2014-11-03T17:45:11.823" LastActivityDate="2014-11-03T17:45:11.823" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9461" PostTypeId="2" ParentId="9446" CreationDate="2014-11-03T15:28:49.440" Score="18" Body="&lt;h1&gt;Longest production run (civil)&lt;/h1&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;Beechcraft Bonanza&lt;/a&gt; seems like a likely candidate for 'oldest design still being made'; first flight was 1945, and it's still in production today (albeit made by the same parent company that makes Cessnas!). Even during the general aviation downturn in the US of the 1980s &amp;amp; 90s, production continued, as &lt;a href=&quot;https://aviation.stackexchange.com/users/1474/kevin-cathcart&quot;&gt;Kevin Cathcart&lt;/a&gt; pointed out in the comments:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FAA registrations show no gap in years of manufacture of the A36 Bonaza. I was able to find a registration for one manufactured in every year from 1980-1999 in california alone. Production did drastically slow during that time frame, but it never stopped.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gLYq8m.jpg&quot; alt=&quot;B35 Bonanza via wikimedia&quot; /&gt;&lt;/p&gt;&#xA;&lt;h1&gt;Longest production run (military)&lt;/h1&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;noreferrer&quot;&gt;Lockheed C-130 Hercules&lt;/a&gt; military transport first flew in 1954 and has been in continuous production ever since. According to Wikipedia, they've even been built in the same factory (in Marietta, Georgia) the entire time.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZYTVbm.jpg&quot; alt=&quot;C-130 prototypes, via Wikimedia&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Because only around 2,300 have been produced (only!), they don't show up on the 'most produced aircraft list' mentioned in another answer.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-07T17:15:45.770" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9462" PostTypeId="1" AcceptedAnswerId="9463" CreationDate="2014-11-03T15:48:32.570" Score="20" ViewCount="5591" Body="&lt;p&gt;This question came up while reading the Wikipedia article on &lt;a href=&quot;http://en.wikipedia.org/wiki/Core_lock&quot;&gt;core lock&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701&quot;&gt;Pinnacle Flight 3701&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If my understanding is right then if for example inner parts of the jet engine heats up that so much that the metal will expand, then after that it cools down rapidly it can result in a lock of the ball bearing of the blades. This means the engine is not functional anymore? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia article says that a windmill and a APU-restart is not possible anymore - is this because the engine has been rendered permanently inoperable?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could somebody explain exactly what a core lock is to me, possibly with pictures?&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="64" LastEditDate="2015-01-11T05:41:41.373" LastActivityDate="2015-01-11T09:08:45.967" Title="What is a &quot;core lock&quot; on an jet-engine?" Tags="&lt;jet-engine&gt;&lt;bombardier&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9463" PostTypeId="2" ParentId="9462" CreationDate="2014-11-03T16:41:03.650" Score="22" Body="&lt;p&gt;There is a good writeup &lt;a href=&quot;http://flightsafety.org/download_file_iframe.php?filepath=/asw/july06/asw_jul06_p44-49.pdf&quot;&gt;here&lt;/a&gt; that explains the engine issues as well as the rest of the incident you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Core lock happens when parts inside the engine cool off at different rates, causing interference between them. In the case of the CF34 engines on these Bombardier jets:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;GE isolated the problem to contact between components of the high-pressure-turbine interstage seal - a static, pressurized honeycomb component - and the rotating seal teeth on the outer torque coupling.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Working on getting a good illustration of what they are talking about.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This does not mean that the engine is &quot;not functional.&quot; There is just much more resistance on the rotating components, but once the temperatures have time to equalize, the components will break free.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to the NTSB, FDR data indicate that the engine cores were beginning to break free just before the impact.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;During core lock, the resistance makes starting the engine more difficult. A windmill start does not provide very much turning force on the engine components, so the resistance from core lock makes that method of starting difficult. GE has done engine testing, and when the windmill restart fails, they are able to use bleed air from the other engine to restart the engine, which provides more turning force.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-11-03T16:41:03.650" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9464" PostTypeId="1" AcceptedAnswerId="9465" CreationDate="2014-11-03T17:11:29.083" Score="9" ViewCount="2987" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html&quot;&gt;According to the AIM&lt;/a&gt;, in class B and C airspace separation of VFR traffic is &quot;suspended during CENRAP operations&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Separation of VFR aircraft will be suspended during CENRAP operations.&#xA;  Traffic advisories and sequencing to the primary airport will be&#xA;  provided on a workload permitting basis. The pilot will be advised&#xA;  when center radar presentation (CENRAP) is in use.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is CENRAP, how are pilots informed that it's in use (i.e. what is the radio phraseology?) and what action is expected from pilots in that case?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-03T17:50:24.210" LastActivityDate="2021-02-02T02:44:22.217" Title="What is CENRAP?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9465" PostTypeId="2" ParentId="9464" CreationDate="2014-11-03T17:17:50.470" Score="10" Body="&lt;p&gt;CENRAP is when an approach control uses the long-range center radars for the separation of their traffic, instead of their normal radars(maintenance, damage, etc). When in this mode, separation standards increase due to the longer rotation/slower update speeds(which allow the longer range visibility) of the Center Radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ever hear about CENRAP, it'll usually be on the ATIS, or the radar facility probably won't provide services to VFR aircraft, just due to the degradation of radar quality.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-11-03T17:17:50.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9466" PostTypeId="1" CreationDate="2014-11-03T18:50:34.177" Score="10" ViewCount="1002" Body="&lt;p&gt;There was a recent accident where SpaceShip2 broke apart in mid-flight, killing one and injuring another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that we can remotely control drones from the other side of the world, why couldn't we do the same with this test airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering that it's all launched locally, it would not even have the lag that drones have.&lt;/p&gt;&#xA;" OwnerUserId="4140" LastEditorUserId="4095" LastEditDate="2014-11-03T21:49:34.480" LastActivityDate="2015-10-03T14:04:50.303" Title="Why aren't test planes remote controlled?" Tags="&lt;flight-testing&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9467" PostTypeId="2" ParentId="9454" CreationDate="2014-11-03T18:50:56.360" Score="56" Body="&lt;p&gt;With a few exceptions (modern aircraft engines with FADEC systems) a &quot;Check Engine&quot; light on an aircraft would be essentially useless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a modern car we have an Engine Control Unit which manages things like mixture and engine timing. The &quot;Check Engine&quot; lamp illuminates when the ECU has detected a fault that requires some sort of attention, but it's not usually specific as to what the fault is or how urgent the problem is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most light GA aircraft (like the Cessna or Cirrus in your question) the engines are straight out of the 1950s/1960s: There are no computers managing the engine for you, and the &lt;em&gt;pilot&lt;/em&gt; is acting as the ECU.&lt;br&gt;&#xA;The pilot should be checking the engine's health regularly (by looking at the engine gauges) and adjusting power, mixture, and propeller pitch as required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since there is no computer supervising the operation of the engine in most light GA aircraft there's no system to determine when the light should be on, so there is no &quot;Check Engine&quot; light.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that some light aircraft do incorporate warning lights for system status information. For example, the status cluster on newer Piper Warriors:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/mRn99.png&quot; alt=&quot;Warrior III warning lights&quot;&gt;&lt;br&gt;&#xA;Top row: Low bus voltage, Pitot Heat off/inop, starter engaged.&lt;br&gt;&#xA;Middle row: Vacuum inop, Alternator inop, Oil Pressure.&lt;br&gt;&#xA;Bottom row: Not used on this aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information provided by these lights is more specific than simply &quot;Check Engine&quot; - directing the pilot's attention to a specific system or condition. The lights are also not a substitute for regularly scanning the engine instruments and managing the powerplant, they're merely a supplement to catch your attention between scans.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-03T18:50:56.360" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9468" PostTypeId="2" ParentId="9466" CreationDate="2014-11-03T19:15:30.230" Score="9" Body="&lt;p&gt;Taking a plane that is designed to be operated by humans and retrofitting a system for remote control would be a big task. They do it with &lt;a href=&quot;http://www.fencecheck.com/content/index.php?title=The_Final_Mission:_The_USAF%92s_QF-4_Target_Drones&quot; rel=&quot;nofollow noreferrer&quot;&gt;old fighter jets&lt;/a&gt; for use as target drones. But a target drone's task is pretty simple; fly like a fighter jet until it gets shot down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the point where SpaceShipTwo is, a bunch of testing has already been done. This is supposed to show that the vehicle is safe enough to move on to piloted testing. But testing aircraft and spacecraft is a dangerous job and &lt;a href=&quot;http://www.ntsb.gov/investigations/fulltext/AAB0401.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;things&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Apollo_1&quot; rel=&quot;nofollow noreferrer&quot;&gt;happen&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Creating a remote control system for an spacecraft like SpaceShipTwo would be much more of an issue. First of all, there will most likely be physical changes required, whether this is to install hardware to manipulate controls, or just electronics to remotely operate the flight computers. These physical changes will be extra work and will affect the tests, since when the plane is actually operating, those things won't be in place. And if those remote control systems fail, you lose the aircraft. Sure, you don't lose pilots, but why lose a plane just because a remote control system (which won't be used on production) fails? Should you spend time and money developing a complicated remote control system, or developing the actual vehicle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, many tests require the pilots to be on board. They are not just testing the systems, but how the pilots interface with them. Having real pilots actually flying the vehicle is the whole point of this phase of testing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this related question as well: &lt;a href=&quot;https://aviation.stackexchange.com/questions/5233/why-do-the-engineers-need-to-be-on-board-during-testing&quot;&gt;Why do the engineers need to be on board during testing?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-11-03T19:15:30.230" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9469" PostTypeId="2" ParentId="9466" CreationDate="2014-11-03T21:27:01.240" Score="9" Body="&lt;p&gt;Today's highly automated airplanes should be not too hard to control remotely - after all, all the cockpit control inputs become electrical signals, and at that point a multichannel remote could be plugged in. The Russians even flew their &lt;a href=&quot;http://en.wikipedia.org/wiki/Buran_(spacecraft)&quot;&gt;Buran&lt;/a&gt; version of the Space Shuttle autonomously, using a neural network to command the craft on its single flight in 1988.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a test pilot flies an aircraft with all his senses. Without the acceleration, a full 3D-view and the force feedback from the controls, he doesn't get the full picture when sitting in a control room and looking at screens full of data. That is done by test engineers anyway, and the pilot's job is to complete the observation of a new airplane's behavior by exposing himself to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might argue that the 3D-view is just a matter of several cameras and displays, but the needed telemetry bandwidth for this would be immense. In a normal test flight, already hundreds of parameters are measured many times a second and transmitted to a ground station, where specialists for each system watch for anomalies in the data. It is much better to spend the telemetry budget for this than to send pictures down. The lack of acceleration and vibration alone would deprive the test pilot of an essential part of the picture, because it simply cannot be realistically recreated in a ground station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the inevitable delays incurred by radio transmission and processing for display will quickly put a pilot out of a loop which he could easily control if he were sitting in the airplane. The range of controllable eigenfrequencies would be reduced to phenomena happening at maybe 0.2 Hertz or less, whereas a pilot in the cockpit can comfortably stay ahead of oscillations with 0.5 Hertz or less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it must be said that sometimes the test pilot does turn out to be a burden for the progress of the flight. On the second flight of the &lt;a href=&quot;http://en.wikipedia.org/wiki/BAC_TSR-2&quot;&gt;British TSR-2 prototype&lt;/a&gt;, one fuel pump began to develop an imbalance, oscillating just at the eigenfrequency of the pilot's eyeballs. He had to throttle back one of the engines to regain his vision.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-03T21:32:17.253" LastActivityDate="2014-11-03T21:32:17.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9470" PostTypeId="2" ParentId="9466" CreationDate="2014-11-03T22:30:29.190" Score="7" Body="&lt;p&gt;Remote control systems have bugs and problems the same as any other system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you install a remote control system, you now have &lt;em&gt;two&lt;/em&gt; systems that need to be tested, checked, maintained and working properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's a problem, and the vehicle crashes, you're immediately left with two possibilities: maybe the aircraft had a problem, or maybe the remote control system had a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the remote control system had a problem, maybe your airplane was fine, and you just lost a perfectly good plane due to a bug in your test system!&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-11-03T22:30:29.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9471" PostTypeId="2" ParentId="3781" CreationDate="2014-11-03T23:00:26.987" Score="9" Body="&lt;p&gt;There's surprisingly little information on this to be found via Google, at least in English, but according to this &lt;a href=&quot;http://www.academia.edu/808103/Air_Traffic_Control_in_Russia&quot;&gt;academic paper&lt;/a&gt; from &lt;a href=&quot;http://www.erau.edu/&quot;&gt;Embry-Riddle&lt;/a&gt; titled &lt;em&gt;Air Traffic Control in Russia&lt;/em&gt;, Soviet controllers operated entirely in Russian, at least within the Soviet Union itself:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Prior to 1991, Soviet air traffic controllers and pilots flying within&#xA;  Soviet airspace were not required to speak English and the majority of&#xA;  them spoke only Russian. After the KAL007 incident, translators were&#xA;  stationed at each of the three main control centers in order to&#xA;  assist with any controllers who encountered English-only pilots, though&#xA;  they weren’t used often (Taubman, 1987).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The cited source is a New York Times &lt;a href=&quot;http://www.nytimes.com/1987/09/17/world/khabarovsk-journal-keeping-the-air-lanes-free-lessons-of-a-horror.html&quot;&gt;article&lt;/a&gt; which says that &quot;80 percent of the civilian air controllers in the Soviet Far East speak some English&quot; but translators (more correctly, interpreters) would be used &quot;in an emergency&quot;, implying that the standard and/or availability of English was very limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you consider the Warsaw Pact in general, then it looks like other languages may have been more common. This &lt;a href=&quot;http://www.mlie.hu/2_2_eng.html&quot;&gt;history of Hungarian ATC&lt;/a&gt; (you have to love the internet!) includes this information about the 1970s:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The regular international cooperation between Air Traffic Controls&#xA;  commenced in the seventies under the aegis of ICAO, since Hungary&#xA;  became one of its regular members. It is more than interesting that&#xA;  the Hungarian controllers had to be able to speak not less than three&#xA;  languages with the flight crews and use not more than three units of&#xA;  measurement, namely the Flight Levels and metric systems of ICAO and&#xA;  the Soviet metric system. [...] Then at last, in 1975, Hungary applied&#xA;  the full ICAO system, but the Russian language as a medium of&#xA;  telecommunication remained in constant use until 1991 when the Soviet&#xA;  military forces left our country, after the 1989 political changes in&#xA;  Hungary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also confirms that Russian was a requirement for ATC controllers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boys in their twenties with more than basic English and Russian&#xA;  language knowledge were the target as new trainee controllers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are also numerous aviation forum threads about Soviet and modern Russian ATC controllers, the overall picture seems to be that there was always &lt;em&gt;some&lt;/em&gt; English spoken by ATC but it was often grudging, limited or just hard to understand. However most commenters (e.g. airline pilots) seem to agree that since the end of the Cold War, it's become much more widespread and the general level of ATC professionalism in Eastern Europe and Russia has improved significantly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-03T23:00:26.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9472" PostTypeId="1" AcceptedAnswerId="9476" CreationDate="2014-11-03T23:34:01.400" Score="6" ViewCount="1895" Body="&lt;p&gt;I enjoy being up in the air.  Planes, gliders, helicopters... you name it, I like it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is an effective way to meet pilots looking for passengers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that some pilots would like passengers to have someone with whom to share the experience, or maybe to gather hours for certifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not looking to go anywhere in particular.  Although I'm open to flying to any destination, just going up in the air and coming back to the same airport is fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I enjoy being aloft in the daytime as well as at night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I simply enjoy the experience of flying and want to connect with pilots who are looking for some company.&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="97" LastEditDate="2014-11-04T00:53:50.787" LastActivityDate="2014-11-04T16:18:02.447" Title="How do you meet pilots looking for passengers?" Tags="&lt;general-aviation&gt;&lt;passenger&gt;&lt;pilots&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9473" PostTypeId="2" ParentId="9472" CreationDate="2014-11-04T02:26:29.373" Score="3" Body="&lt;p&gt;Aviation, for me, is a lifestyle more than anything.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some background: I'm still a college student, but I'm going into the Air Force, I am on my school's flight team, I am getting a degree in asto engineering (and astro physics).  Almost everyone I know is involved in aviation or space in one way or another.  We fly around the southwest part of the country all the time, but it's normal.  One weekend I'll fly LA, and another a friend will take us to Vegas.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you considered going to flight training, yourself?  If you find a good flight school, you wont only learn to fly yourself, but you will meet other people like you.  And once you become friends with them you can all fly each other after you get your licences.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Honestly, I would be pretty uncomfortable flying with someone I don't know next to me.  For example, If you've ever picked up a hitch-hiker you might know how it's a bit awkward and uncomfortable making small talk with a completely random person.  Now imagine what that would be like in an airplane... a plane that most likely has controls in both (front) seats, and could do serious damage if used improperly. &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2014-11-04T02:47:43.623" LastActivityDate="2014-11-04T02:47:43.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9474" PostTypeId="2" ParentId="9454" CreationDate="2014-11-04T06:14:20.540" Score="0" Body="&lt;p&gt;The approach taken in designing aircraft, and certifying their equipment, is to provide for the greatest reliability at the cost of increase pilot workload. The pilot mostly has very little to do for a majority of the flight, being cruise-at-altitude, so it makes sense to require the pilot to scan and interpret simple, reliable indications of current engine status, and draw inferences as to the operational health of the engine as a whole.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the process by which fuel and air is mixed in the carburetor of a non-turbine engine is completely a manually-controlled process. The human is involved as the feedback control element in a closed-loop system, where the mixture control (lean to rich) is the effector, and the RPM and altitude gauges, or the Exhaust Gas Temperature gauge (EGT) are the affectors. The pilot adjusts the mixture to the point which peaks EGT or RPM, and perhaps makes a small adjustment &quot;in the rich direction for cooling&quot;, but this is done during climb and descent, as the altitude is changing, and is completely initiated by the pilot (frequently prompted by an item on a climb or cruise flight phase checklist).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not delegate this task to an automatic system? Well, first of all, that would provide another point of failure. The EGT and RPM indicators are quite robust and unlikely to fail; likewise with the mixture adjustment knob/lever. The pilot provides the &quot;complex&quot; control system closed-loop control. Imagine if the controller of an automatic system were to fail, and the engine remained in its leanest setting during descent? The system could go into pre-ignition or worse, pre-detonation, leading to a catastrophic failure of the engine! No, the FAA and aircraft builders err on the side of fewer automatic systems in favor of simplicity and reliability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someday ask a pilot about all the various things they must tend to, which could be attended to by a modern, computer controlled automatic system. You'll be surprised!&lt;/p&gt;&#xA;" OwnerUserId="2678" LastActivityDate="2014-11-04T06:14:20.540" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9475" PostTypeId="1" AcceptedAnswerId="9558" CreationDate="2014-11-04T06:46:14.997" Score="12" ViewCount="755" Body="&lt;p&gt;I'm having trouble figuring out the correct procedure to enter an approach such as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oSzrL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oSzrL.jpg&quot; alt=&quot;FHR NDB RWY 34&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you are cleared from ISLND for the NDB approach.  How do you maneuver safely and legally to the the outbound leg once you reach the IAF?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is the correct way would be a turn to the outbound course from the NDB.  Then a right turn direct to the NDB and a direct entry to the outbound course, then proceed as charted.&lt;/p&gt;&#xA;" OwnerUserId="3516" LastEditorUserId="572" LastEditDate="2015-02-19T08:52:15.083" LastActivityDate="2020-12-12T23:27:55.740" Title="How do you properly enter the NDB34 published approach at Friday Harbor (KFHR)?" Tags="&lt;iaps&gt;&lt;instrument-procedures&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9476" PostTypeId="2" ParentId="9472" CreationDate="2014-11-04T06:52:03.317" Score="2" Body="&lt;p&gt;Well if you are in Australia I'd love to take you for a spin!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to find your local aviation community. Online, airport open days, the local aero club, flying schools, aviation events, and even at the fence of the airport - you'll find people if you go looking. In any aviation enthusiast group you're likely to find at least one private pilot. Build up a bit of a rapport and just ask them to take you up. Just be genuine, talk about what you love about flying, don't look shocked when they say you have to pay half (remembering that private pilots are not allowed to earn money for it, so don't let yourself get ripped off), and offer to buy them a beer afterwards or something :) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT - I add the beer comment as a bit of a joke. Although it's always nice to get that bit of gratitude from a passenger, a pilot trying to build hours before going commercial would simply be thrilled to not have to pay for a full hour! &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2014-11-04T07:11:54.480" LastActivityDate="2014-11-04T07:11:54.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9477" PostTypeId="2" ParentId="2360" CreationDate="2014-11-04T07:13:52.140" Score="1" Body="&lt;p&gt;Also Zlin 142 has forward swept wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not for aerodynamic reasons, but to place the pilots at the center of gravity and the spar behind them.&lt;/p&gt;&#xA;" OwnerUserId="4145" LastEditorUserId="1961" LastEditDate="2014-11-04T07:49:42.637" LastActivityDate="2014-11-04T07:49:42.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9478" PostTypeId="1" CreationDate="2014-11-04T10:01:03.447" Score="1" ViewCount="991" Body="&lt;p&gt;This question came up while reading an article about &lt;a href=&quot;http://listverse.com/2013/07/26/10-mysterious-plane-crashes/&quot; rel=&quot;nofollow&quot;&gt;mysterious plane incidents&lt;/a&gt;. It told that some airlines do not use the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_191&quot; rel=&quot;nofollow&quot;&gt;flight number 191&lt;/a&gt; because of bad luck. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In fact, there have been so many catastrophes that, much like hotel&#xA;  owners who refuse to have a 13th floor, some superstitious airlines&#xA;  have completely done away with the number “191.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does somebody know some Airlines who are not using this flight number&#xA;for that reason?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2020-10-06T07:11:10.380" Title="Which Airline don't use the Flight Number 191 anymore because of bad luck?" Tags="&lt;accidents&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9479" PostTypeId="1" AcceptedAnswerId="9493" CreationDate="2014-11-04T13:51:53.730" Score="11" ViewCount="2560" Body="&lt;p&gt;I was watching a Video of a &lt;a href=&quot;https://www.youtube.com/watch?v=OoK_dbLDfA0&quot;&gt;Korean Air 777-300&lt;/a&gt; landing at Narita International Airport (IATA: NRT). The Comments on the YouTube Video are again unprofessional. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I want to ask here, what caused this very bumpy landing?&lt;/li&gt;&#xA;&lt;li&gt;Some comments state this was a wind-shear, is that correct?&lt;/li&gt;&#xA;&lt;li&gt;Is required by rule to make a maintenance check after such a landing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="19" LastEditDate="2016-12-05T11:32:05.103" LastActivityDate="2016-12-05T11:32:05.103" Title="Was this bumpy Boeing 777-300 landing caused by windshear?" Tags="&lt;wind&gt;&lt;boeing-777&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9480" PostTypeId="2" ParentId="9479" CreationDate="2014-11-04T14:15:39.330" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;what caused this very bumpy landing?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like it was initially triggered by a sudden change in crosswinds, a strong gust,  perhaps a microburst?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like the pilot then had trouble correcting for the bounce of the right side undercarriage at the same time as dealing with the crosswinds lifting the wings while simultaneously keeping the aircraft aligned on the runway.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Some comments state this was a wind-shear, is that correct?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From what I've read, the term &lt;a href=&quot;http://en.wikipedia.org/wiki/Wind_shear#Where_and_when_it_is_strongly_observed&quot; rel=&quot;nofollow noreferrer&quot;&gt;wind-shear&lt;/a&gt; is mostly used of sudden differences in wind direction and speed at different altitudes, it wouldn't apply a few feet above a runway. It could be a downburst or microburst though - they are related phenomenon.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is required by rule to make a maintenance check after such a landing?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've read that the airline ground-crew can read-out the G-forces  experienced during landing and vertical speed at touchdown. If certain thresholds were exceeded, checks would be carried out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines are &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_operations_quality_assurance&quot; rel=&quot;nofollow noreferrer&quot;&gt;required by ICAO&lt;/a&gt; to use Flight Data Monitoring (FDM) to improve safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OnSs5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;From &lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP739.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAA CAP 739 Flight Data Monitoring&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-11-04T14:54:20.863" LastActivityDate="2014-11-04T14:54:20.863" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9481" PostTypeId="2" ParentId="9454" CreationDate="2014-11-04T14:42:38.907" Score="5" Body="&lt;p&gt;The reason the &quot;Check Engine&quot; light, called the Malfunction Indicator Lamp (MIL), exists in cars is due to legislation.  Road vehicles have strict EPA standards to follow regarding emissions that include not only the exhaust and air/fuel mixture, but the fuel tank evaporation, and crankcase oil ventilation. The only way to meet these standards is by computer control of the engine and other aspects of the vehicle.  The light is mandated to indicate when any one of these systems isn't operating within specification, and thus may have higher emissions than what meets the standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While drivers think of the light as an early warning indicator for vehicle trouble, the reality is that its primary purpose is to encourage drivers to keep their vehicle within the emissions standards it was originally designed for.  These change over the years, newer cars have more strict standards to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small aircraft follow the &lt;a href=&quot;http://www.epa.gov/otaq/aviation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;non-road emissions standards&lt;/a&gt;, similar to construction equipment, lawnmowers, generators, and off-road vehicles. None of these are required to follow such strict standards (though they must meet minimum standards, and these are getting more involved), and the standards they do follow can be done with no computer control. There is no legislation that requires a lamp indicating that the engine is operating at higher emissions than intended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger aircraft have lower emissions because they are required by customers to be very fuel efficient, and one way to increase fuel efficiency is to add computer control that uses as much energy from the fuel as possible, thus burning it more completely.  These systems are expensive, though, and only make financial sense if the aircraft is going to be flown many, many hours over its lifetime. They also do follow stricter standards, but the indicator lamps and manufacturer diagnostic equipment are more comprehensive for these aircraft to enable overall cost-savings and increased reliability/safety required for passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.epa.gov/otaq/aviation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;EPA is due to make recommendations&lt;/a&gt; in late 2015 and early 2016 that will affect aircraft emissions.  At that point in time it may be that new aircraft will need to be under computer control and will need a check engine lamp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might be fundamentally different though.  In a road vehicle if there's a problem, you don't need to know what it is to be safe - you can pull over and call a tow truck.  Aircraft have no such luxury, so while there may be a lamp indicating excessive emissions, chances are good pilots will still rely on multiple other indicators to determine what malfunction has occurred so they can respond best to the circumstances.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastEditorUserId="753" LastEditDate="2019-02-14T13:02:55.903" LastActivityDate="2019-02-14T13:02:55.903" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9482" PostTypeId="2" ParentId="9472" CreationDate="2014-11-04T16:02:39.233" Score="2" Body="&lt;p&gt;You need to be aware that the holder of a Private Pilot Certificate (the entry level certificate that permits the carriage of Passengers) has rules that prohibit the pilot from &quot;holding out&quot;, a term that implies the pilot is soliciting passengers.  So if you just blow into the local FBO and ask someone to take you up, there will be an immediate suspicion that you are from the FAA and may possibly be setting up a trap for the pilot.  IT IS VERY UNLIKELY that entrapment will be happening!  However, the fear of it may deter a pilot from saying yes, just as the fear of security concerns mentioned in other answers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As suggested above, find a pilot group somewhere and build up a rapport with one or more pilots.  Then ask.   &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-11-04T16:02:39.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9483" PostTypeId="2" ParentId="9472" CreationDate="2014-11-04T16:18:02.447" Score="2" Body="&lt;p&gt;I'm assuming here that you're thinking of a 'free' or cost-sharing ride with a pilot, rather than actually hiring someone to fly you. In short, it may be possible but it depends on having a good relationship with the pilot and there could be some legal/regulatory issues (especially in the US, if that's where you are).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you just want to fly as a passenger for the fun and experience, with no expectations at all about the route or duration of flight then the best thing you can do is to get involved in your local aviation community and make some contacts. I suspect that few pilots will take a complete stranger for a ride (see below for some US-centric reasons why not), but if you're a friend of a friend or a non-flying member of a flying club or whatever then that can open doors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, learning to fly would be an obvious way to get involved. If costs are a concern then you could consider gliding, which is significantly cheaper but would still let you make a lot of local aviation contacts. Or see if a local airport needs people to &lt;a href=&quot;http://www.ehow.com/facts_5888165_aircraft-lineman-job-description.html&quot; rel=&quot;nofollow&quot;&gt;work on the line&lt;/a&gt;. Or maybe you have a complementary interest like photography and you can ask around at a local airport to see if any pilots would take you. But ultimately you'll have to establish a relationship of some kind with a pilot in order to go fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, from the pilot's perspective there are some downsides to taking a 'random' stranger for a ride. First is simply trust and personal comfort level: do I want someone I don't know flying with me and (in most light aircraft) having access to the controls? Personally, I'd be concerned about possible panic attacks or simple motion sickness; someone trying to take over the aircraft is so unlikely that I think it's not worth worrying about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second - at least in the US, I don't know where you are - it's strictly forbidden for non-commercial pilots to receive any compensation for flying. &quot;Compensation&quot; is very broadly defined and even includes flying time itself, so if you want (or the pilots wants you) to contribute to the cost of the flights then it needs to be legal: the pilot must always pay at least his &lt;em&gt;pro rata&lt;/em&gt; share. In most cases this isn't an issue because practically speaking the FAA has no way to know what private arrangements you've made and they certainly don't care if someone takes a friend for a flight and gets a free lunch in return. But there are limits: some companies are trying to create 'ride sharing' services to match pilots with passengers but the FAA has already &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2014/macpherson-jonesday%20-%20(2014)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow&quot;&gt;said&lt;/a&gt; that it's illegal for private pilots to participate in them. &lt;a href=&quot;https://airpooler.com/&quot; rel=&quot;nofollow&quot;&gt;Airpooler&lt;/a&gt; is the most prominent case, and their &lt;a href=&quot;https://airpooler.com/faqpassengers/&quot; rel=&quot;nofollow&quot;&gt;carefully worded FAQ&lt;/a&gt; saying that pilots are not compensated didn't persuade the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally there's liability: I know that many private pilots refuse to fly with passengers they don't know well because the risk of a lawsuit is so high in the case of an accident. I'm not saying that you personally would sue, but (in the worst case) your family or estate might.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So all in all, your best option is to get to know some pilots personally by whatever means works best for you given your location, interests and general access to aviation. I know that's a very vague answer, but a lot depends on your personal situation.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-04T16:18:02.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9484" PostTypeId="2" ParentId="9479" CreationDate="2014-11-04T16:55:44.360" Score="5" Body="&lt;h1&gt;How did it happen?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I watched the video closely and coordinated the movement of the ailerons with the motion of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to me that there was a strong gust from the left moments before touchdown. As a result the left wing is lifted by the crosswind and the aircraft, still in the air, side-skid to the right. Exactly when the right main gear touches the ground, the gust dies down and the pilot has input left aileron to counter the roll. This initiated the bouncing sequence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all the subsequent bouncing, the pilot was trying to determine how much left aileron is necessary to counter the crosswind. The technique is correct, but the crosswind now is much weaker than it was 2 seconds ago; he also had to level the wings which are rolled left at this point. Unfortunately the rhythm he applies correction matches with the rhythm the plane bounces, resulting in a brief &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot-induced_oscillation&quot; rel=&quot;nofollow&quot;&gt;pilot induced oscillation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Wind shear?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I agree with RedGrittyBrick - I wouldn't call the gust at an altitude of a few feet a wind shear.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Maintenance check required?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In some airplanes the g-meter needle stops at the peak value during the flight. If it exceeds a certain threshold, a check is required. I'm not a real life 777 pilot, but my knowledge of the 777 does not recall such an instrument in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Required or not, good airmanship should lead the crew to write this down in the maintenance log for ground engineers to review. Personally I don't think this was a particularly hard landing that would lead to bent parts, though my instructor would remind me: &quot;when it doubt, take the safe way&quot;.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="938" LastEditDate="2014-11-04T18:08:23.147" LastActivityDate="2014-11-04T18:08:23.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9485" PostTypeId="2" ParentId="9478" CreationDate="2014-11-04T17:18:34.857" Score="2" Body="&lt;p&gt;Well, you can be pretty sure that Delta and American no longer use that flight number, as it is pretty standard for airline to retire a flight number of an accident flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, I'm sure there are a multitude of carriers still using Flight 191.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Air India 191 is &lt;a href=&quot;http://uk.flightaware.com/live/flight/AIC191&quot; rel=&quot;nofollow&quot;&gt;in-flight&lt;/a&gt; at the time of writing . Air Canada 191 is &lt;a href=&quot;https://uk.flightaware.com/live/flight/ACA191&quot; rel=&quot;nofollow&quot;&gt;scheduled&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2014-11-04T17:18:34.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9486" PostTypeId="1" AcceptedAnswerId="9506" CreationDate="2014-11-04T18:06:51.290" Score="4" ViewCount="5596" Body="&lt;p&gt;The carry-on baggage policy on British Airways &lt;a href=&quot;http://www.britishairways.com/en-gb/information/baggage-essentials/hand-baggage-allowances&quot; rel=&quot;nofollow noreferrer&quot;&gt;states that:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Maximum weight per bag is up to 23 kg (51lbs).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Two passengers, with bags near the weight limit could easily go well over 40 kg. And then there will be a few smaller laptop bags etc. inevitably stuffed into the overhead compartment, I imagine it can touch 50 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the overhead compartments themselves have a stated limit of 32 kg. Isn't this an unsafe practice? If so, how is British Airways permitted to do so, and if not, why do other airlines not follow the same practice?&lt;/p&gt;&#xA;" OwnerUserId="4153" LastEditorUserId="1858" LastEditDate="2017-12-30T13:00:16.977" LastActivityDate="2017-12-30T13:00:16.977" Title="How does British Airways permit a 23 kg bag in hand baggage?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9487" PostTypeId="1" CreationDate="2014-11-04T19:05:59.760" Score="6" ViewCount="1575" Body="&lt;p&gt;Have any aircraft, military or civilian, ever been attacked by &lt;a href=&quot;http://en.wikipedia.org/wiki/CBRN_defense&quot; rel=&quot;noreferrer&quot;&gt;chemical, biological, radiological or nuclear&lt;/a&gt; weapons?&lt;/p&gt;&#xA;&lt;p&gt;Terrorist attacks and test firings included. Attacks on persons on-board the aircraft (rather than the aircraft itself) included.&lt;/p&gt;&#xA;&lt;p&gt;Information security attacks on the aircraft itself (such as computer viruses) would also be of interest, although I'll exclude jamming of communications and sensors such as radar.&lt;/p&gt;&#xA;&lt;p&gt;Sources I've already consulted:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://books.google.co.uk/books?id=8uhpSnh8b8wC&amp;amp;printsec=frontcover&quot; rel=&quot;noreferrer&quot;&gt;Airport and Aviation Security&lt;/a&gt;, Elias&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/United_States_Army_CBRN_School&quot; rel=&quot;noreferrer&quot;&gt;USACBRN School&lt;/a&gt;, Wikipedia&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.stratfor.com/weekly/20100210_jihadist_cbrn_threat&quot; rel=&quot;noreferrer&quot;&gt;The Jihadist CBRN Threat&lt;/a&gt;, Stratfor&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.avsecprofessionals.org/Publications_files/NBC%20Int%27l%20Flying%20high%20flying%20safe.pdf&quot; rel=&quot;noreferrer&quot;&gt;Flying High, Flying Safe,&lt;/a&gt; Wolff&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://books.google.co.uk/books?id=KPXXn6Y2OAUC&amp;amp;pg=PA338&amp;amp;lpg=PA338&quot; rel=&quot;noreferrer&quot;&gt;Practical Aviation Security&lt;/a&gt;, Price &amp;amp; Forrest&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://books.google.co.uk/books?id=9Ljhn2R_YF8C&quot; rel=&quot;noreferrer&quot;&gt;Counterterrorism: A Reference Handbook&lt;/a&gt;, Steven &amp;amp; Gunaratna&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Definition of 'chemical weapon': sure, explosives are made out of chemicals (as is everything else) but I'm talking about chemical weapons as defined by the &lt;a href=&quot;http://www.opcw.org/about-chemical-weapons/what-is-a-chemical-weapon/&quot; rel=&quot;noreferrer&quot;&gt;Organisation for the Prohibition of Chemical Weapons&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The term chemical weapon is applied to any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves.&lt;/p&gt;&#xA;&lt;p&gt;The toxic chemicals that have been used as chemical weapons, or have been developed for use as chemical weapons, can be categorised as choking, blister, blood, or nerve agents. The most well known agents are as follows: choking agents—chlorine and phosgene, blister agents (or vesicants)—mustard and lewisite, blood agents—hydrogen cyanide, nerve agents—sarin, soman, VX.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For 'radiological weapons', I'm not talking about visible electromagnetic radiation (light) or invisible electromagnetic radiation (radio etc) but rather &lt;a href=&quot;http://en.wikipedia.org/wiki/Radiological_weapon&quot; rel=&quot;noreferrer&quot;&gt;radiological dispersion devices&lt;/a&gt;, defined by the US Department of Defence as:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;any device, including any&#xA;weapon or equipment, other than a nuclear explosive device, specifically designed to employ&#xA;radioactive material by disseminating it to cause destruction, damage, or injury by means of the&#xA;radiation produced by the decay of such material&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Ford, J. (March 1998). Radiological Dispersion Devices: Assessing the transnational threat. National Defense University - Institute for National Strategic Studies - Strategic Forum, No. 136.&lt;/em&gt; as cited in &lt;em&gt;&lt;a href=&quot;http://digitalcommons.liberty.edu/gov_fac_pubs/47&quot; rel=&quot;noreferrer&quot;&gt;Rickert, Paul R., &amp;quot;The Likely Effect of a Radiological Dispersion Device&amp;quot; (2005). Faculty Publications and Presentations. Paper 47.&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;'Biological weapons' as &lt;a href=&quot;http://www.unog.ch/80256EE600585943/(httpPages)/29B727532FECBE96C12571860035A6DB?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;defined by the United Nations&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Biological weapons are complex systems that disseminate disease-causing organisms or toxins to harm or kill humans, animals or plants. They generally consist of two parts – a weaponized agent and a delivery mechanism. In addition to strategic or tactical military applications, biological weapons can be used for political assassinations, the infection of livestock or agricultural produce to cause food shortages and economic loss, the creation of environmental catastrophes, and the introduction of widespread illness, fear and mistrust among the public.&lt;/p&gt;&#xA;&lt;p&gt;Almost any disease-causing organism (such as bacteria, viruses, fungi, prions or rickettsiae) or toxin (poisons derived from animals, plants or microorganisms, or similar substances produced synthetically) can be used in biological weapons. The agents can be enhanced from their natural state to make them more suitable for mass production, storage, and dissemination as weapons. Historical biological weapons programs have included efforts to produce: aflatoxin; anthrax; botulinum toxin; foot-and-mouth disease; glanders; plague; Q fever; rice blast; ricin; Rocky Mountain spotted fever; smallpox; and tularaemia, among others.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4067" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-03-18T13:24:29.680" Title="Have any aircraft ever been attacked by chemical, biological, radiological or nuclear weapons? Information security compromises?" Tags="&lt;military&gt;&lt;terrorism&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9488" PostTypeId="2" ParentId="9475" CreationDate="2014-11-04T19:14:53.373" Score="5" Body="&lt;p&gt;Since the NDB is the only navigational reference, you don't have much choice but to fly right over it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, ISLND direct FHR, turn right and intercept 159 FROM, as indicated. Once you're established on the 159 FROM, do the procedure turn exactly as shown, and stay within 10NM of the NDB.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice all maneuvering is to the east of FHR, that's the &quot;safe area,&quot; since there are two obstacles on the west side @424ft and 1100ft, as well as the Canadian border.&lt;/p&gt;&#xA;" OwnerUserId="4154" LastEditorUserId="3504" LastEditDate="2014-11-05T20:14:47.277" LastActivityDate="2014-11-05T20:14:47.277" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9489" PostTypeId="2" ParentId="9487" CreationDate="2014-11-04T20:17:07.537" Score="7" Body="&lt;p&gt;What immediately comes to mind is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_XF-90&quot; rel=&quot;nofollow&quot;&gt;Lockheed XF-90&lt;/a&gt;, an early US jet fighter, which had a very strong and heavy airframe. For that reason, the second prototype (of only two ever built) was subjected in 1952 to three nuclear bomb tests in the Nevada desert (not in flight, however. It was sitting on the ground).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this time, an unguided nuclear-armed air-to-air missile, the &lt;a href=&quot;http://en.wikipedia.org/wiki/AIR-2_Genie&quot; rel=&quot;nofollow&quot;&gt;Douglas AIR-2 Genie&lt;/a&gt;, was developed and &lt;a href=&quot;http://en.wikipedia.org/wiki/Operation_Plumbbob&quot; rel=&quot;nofollow&quot;&gt;tested once in 1957&lt;/a&gt;. Several USAF officers &lt;a href=&quot;http://nuclear-news.net/2013/07/15/nuclear-weapons-insanity-americas-air-2-genie-rocket/&quot; rel=&quot;nofollow&quot;&gt;were standing below the test spot&lt;/a&gt;, but no aircraft were used as targets. The missile was fired by an &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_F-89_Scorpion&quot; rel=&quot;nofollow&quot;&gt;F-89 Scorpion&lt;/a&gt; and could be carried by the F-101, the F-104 and the F-106.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of the AIR-2 was to attack tight formations of &lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-4&quot; rel=&quot;nofollow&quot;&gt;Tupolev Tu-4&lt;/a&gt; bombers in the days before guided SAM missiles were available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am sure the Russians had their own score of nuclear tests on aircraft, but I do not know anything specific.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-05T09:16:37.107" LastActivityDate="2014-11-05T09:16:37.107" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9490" PostTypeId="2" ParentId="9487" CreationDate="2014-11-04T20:36:39.463" Score="5" Body="&lt;p&gt;I've found a few instances myself:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Radiological&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;As part of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Alexander_Litvinenko&quot; rel=&quot;nofollow noreferrer&quot;&gt;Litvinenko case&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;During the investigation into his death it was learned that a number of British Airways aircraft that flew between Moscow and London had been contaminated with the radioactive material [Polonium-210].&lt;/p&gt;&#xA;&lt;p&gt;... 33,000 passengers potentially exposed ... very low traces ... the risk to public health proved to be low&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Source is &lt;a href=&quot;http://content.yudu.com/A24nep/ASIApr2013/resources/22.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Security International, April 2013&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Information Security&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In theory, a hacker could use a plane's onboard WiFi signal or inflight entertainment system to hack into its avionics equipment, potentially disrupting or modifying satellite communications, which could interfere with the aircraft's navigation and safety systems, Santamarta said.&lt;/p&gt;&#xA;&lt;p&gt;He acknowledged that his hacks have only been tested in controlled environments, such as IOActive's Madrid laboratory, and they might be difficult to replicate in the real world. Santamarta said he decided to go public to encourage manufacturers to fix what he saw as risky security flaws.&lt;/p&gt;&#xA;&lt;p&gt;Representatives for Cobham, Harris, Hughes and Iridium said they had reviewed Santamarta's research and confirmed some of his findings, but downplayed the risks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.reuters.com/article/2014/08/04/us-cybersecurity-hackers-airplanes-idUSKBN0G40WQ20140804&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hacker says to show passenger jets at risk of cyber attack&lt;/a&gt;, Reuters&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;it's possible to take control of aircraft flight systems and communications using an Android smartphone and some specialized attack code.&lt;/p&gt;&#xA;&lt;p&gt;Hugo Teso, a security researcher at N.Runs and a commercial airline pilot, spent three years developing the code, buying second-hand commercial flight system software and hardware online and finding vulnerabilities within it. His presentation will cause a few sleepless nights among those with an interest in aircraft security.&lt;/p&gt;&#xA;&lt;p&gt;Teso's attack code, dubbed SIMON, along with an Android app called PlaneSploit, can take full control of flight systems and the pilot's displays. The hacked aircraft could even be controlled using a smartphone's accelerometer to vary its course and speed by moving the handset about.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;You can use this system to modify approximately everything related to the navigation of the plane,&amp;quot; Teso told Forbes. &amp;quot;That includes a lot of nasty things.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theregister.co.uk/2013/04/11/hacking_aircraft_with_android_handset/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Researcher hacks aircraft controls with Android smartphone&lt;/a&gt;, The Register&lt;br&gt;&#xA;See also: &lt;a href=&quot;http://conference.hitb.org/hitbsecconf2013ams/materials/D1T1%20-%20Hugo%20Teso%20-%20Aircraft%20Hacking%20-%20Practical%20Aero%20Series.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Conference presentation from security researcher Hugo Teso&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;However, the FAA issued a response in a statement to journalists:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The FAA is aware that a German information technology consultant has alleged he has detected a security issue with the Honeywell NZ-2000 Flight Management System (FMS) using only a desktop computer.&lt;/p&gt;&#xA;&lt;p&gt;The FAA has determined that the hacking technique described during a recent computer security conference does not pose a flight safety concern because it does not work on certified flight hardware.&lt;/p&gt;&#xA;&lt;p&gt;The described technique cannot engage or control the aircraft’s autopilot system using the FMS or prevent a pilot from overriding the autopilot. Therefore, a hacker cannot obtain “full control of an aircraft” as the technology consultant has claimed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;as did the EASA:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For more than 30 years now, the development of certifiable embedded software has been following strict guidance and best practices that include in particular robustness that is not present on ground-based simulation software.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and equipment manufacturer Rockwell Collins:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Today’s certified avionics systems are designed and built with high levels of redundancy and security.&lt;/p&gt;&#xA;&lt;p&gt;The research by Hugo Teso involves testing with virtual aircraft in a lab environment, which is not analogous to certified aircraft and systems operating in regulated airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://nakedsecurity.sophos.com/2013/04/16/airplane-hack-security-faa/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA and security researchers at odds over airplane hack security&lt;/a&gt;, &lt;em&gt;Sophos Naked Security&lt;/em&gt;, 16 April 2013&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Information Security (?) - drone&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Iran claims to have caused a US drone to land through a cyber-attack, in Dec 2011.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;ISTANBUL, TURKEY — Iran guided the CIA's &amp;quot;lost&amp;quot; stealth drone to an intact landing inside hostile territory by exploiting a navigational weakness long-known to the US military, according to an Iranian engineer now working on the captured drone's systems inside Iran.&lt;/p&gt;&#xA;&lt;p&gt;Iranian electronic warfare specialists were able to cut off communications links of the American bat-wing RQ-170 Sentinel, says the engineer, who works for one of many Iranian military and civilian teams currently trying to unravel the drone’s stealth and intelligence secrets, and who could not be named for his safety.&lt;/p&gt;&#xA;&lt;p&gt;Using knowledge gleaned from previous downed American drones and a technique proudly claimed by Iranian commanders in September, the Iranian specialists then reconfigured the drone's GPS coordinates to make it land in Iran at what the drone thought was its actual home base in Afghanistan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.csmonitor.com/World/Middle-East/2011/1215/Exclusive-Iran-hijacked-US-drone-says-Iranian-engineer-Video&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.csmonitor.com/World/Middle-East/2011/1215/Exclusive-Iran-hijacked-US-drone-says-Iranian-engineer-Video&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;US confirms the drone was downed but does not confirm a successful cyberwarfare attack.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incident&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://en.wikipedia.org/wiki/Iran%E2%80%93U.S._RQ-170_incident&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4067" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-14T19:58:13.770" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9491" PostTypeId="1" AcceptedAnswerId="9512" CreationDate="2014-11-04T20:49:18.290" Score="6" ViewCount="8082" Body="&lt;p&gt;Are some light aircraft known as being significantly quieter in the cockpit than others ? How quiet might the quietest light aircraft be from the inside ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least ten years ago I was reading an aviation magazine and there was an article about someone who had gone all out to make their aircraft cockpit as quiet as possible. I can't remember the details but they'd made a whole lot of modifications with sound reduction in mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ever since then I've wondered: are some light aircraft really noticeably quieter than others (and do they get sold on the basis of them being quieter) and is modding your aircraft to make it quieter a common thing ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I am of course referring to closed cockpit aircraft, I appreciate a Gypsy Moth would inevitably be quite noisy !).&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="19" LastEditDate="2017-01-25T10:57:18.597" LastActivityDate="2018-07-17T18:34:11.170" Title="Which light aircraft are known to have a quiet cockpit?" Tags="&lt;general-aviation&gt;&lt;cockpit&gt;&lt;noise&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9492" PostTypeId="2" ParentId="9454" CreationDate="2014-11-04T20:55:33.117" Score="1" Body="&lt;p&gt;The &quot;check engine&quot; light on a car is triggered by the on-board diagnostics computer that most every (if not every) car manufactured since 1997 has been required to have (if it is to meet U.S. standards, anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, small airplane engines, due to the very conservative nature of aviation, the cost of certification (even just certifying a change to an existing design), and concerns about reliability and redundancy, are almost unchanged since the '50s (no on-board computer, for example).  Fuel-injected engines, I believe, are all mechanically operated, rather than electronic like you would have in your car.  Without an on-board computer or electronics, there is nothing to trigger the warning lights that we've taken for granted for the last twenty years in our cars*.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Many small airplane engines do have at least a couple of warning lights, such as low-voltage, low oil pressure, etc., but they are controlled by simple relays rather than by a computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: I'm a flight instructor, and flew an &quot;amateur-built experimental&quot; airplane for a few years.&lt;/p&gt;&#xA;" OwnerUserId="4158" LastActivityDate="2014-11-04T20:55:33.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9493" PostTypeId="2" ParentId="9479" CreationDate="2014-11-04T21:02:56.297" Score="21" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Some comments state this was a wind-shear, is that correct?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Looking at the windsock which appears in the right bottom corner at 0:12 and remains visible for about 4 seconds, you can tell there is little wind, not what you would associate with wind shear. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I want to ask here, what caused this very bumpy landing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is always hard to judge the actions of the pilots without knowing what was going on in the cockpit, and what control inputs were given. But by looking at the position of the control surfaces I am fairly sure that this is a case of &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot-induced_oscillation&quot; rel=&quot;noreferrer&quot;&gt;Pilot Induced Oscillations&lt;/a&gt;. I.e. the pilot tries to correct a disturbance but his efforts cause the aircraft to overshoot to the other side of the desired attitude, leading to an increasing series of corrections in opposite directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to me that the flare is a tad early, causing the aircraft to float over the runway. At the same time several cycles of alternating roll inputs are given, causing increasing oscillations. I could distinguish at least 3 full cycles before touchdown. Every cycle is a bit stronger than the previous one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last right-wind-down command before touchdown is strong enough for all the starboard spoiler to deflect. This, combined with the low speed due to early flare causes the right wing to loose most of its lift. The aircraft touches down hard on its right gear first. At the moment of touchdown, the roll command is strongly left wing down as can be seen from the spoiler extension on the left wing. With almost no lift on the left side and standing on the right gear, the aircraft rapidly rolls to the left.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The left roll is then counteracted again with right ailerons up but too late; the right gear lifts of again. When then right gear touches for the second time, still a right wing down command is given, causing the right roll to continue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This process of chasing the roll is continued and mixed with similar behaviour in pitch. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NEaiQ.png&quot; alt=&quot;Roll right&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Command right wing down, slight spoiler deflection&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/roYST.png&quot; alt=&quot;Roll left&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Command left wing down, slight spoiler deflection&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gqjqK.png&quot; alt=&quot;Roll right&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Command right wing down, slight spoiler deflection&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EDNwL.png&quot; alt=&quot;Roll left&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Command left wing down, slight spoiler deflection&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/B5Qsx.png&quot; alt=&quot;Roll right&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Command right wing down, right spoiler deflection. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EA08p.png&quot; alt=&quot;Touch right, roll left&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Touch right gear down,  left wing down, left spoiler deflection. This causes a rapid left roll.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N3d1d.png&quot; alt=&quot;Touch left, roll right&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Touch left gear down, right gear looses contact, right side spoiler deflection. This causes a rapid right roll. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NRVvx.png&quot; alt=&quot;While rolling right, command right&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Halfway the roll to the right, all main wheels are on the ground. Instead of damping the roll by left deflection, a right roll is still commanded. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This continues down the runway, also combined with pitch oscillations. Every time the pilot corrects, he is essentially too late to damp the oscillations. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is required by rule to make a maintenance check after such a landing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If a hard landing is made, the aircraft will detect that by itself and will send a report to maintenance if a hard landing check is required. See &lt;a href=&quot;http://www.google.nl/patents/US20110276217&quot; rel=&quot;noreferrer&quot;&gt;this published patent application&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2015-11-29T03:28:32.643" LastActivityDate="2015-11-29T03:28:32.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9494" PostTypeId="1" CreationDate="2014-11-04T21:23:35.710" Score="11" ViewCount="2461" Body="&lt;p&gt;Does the pressure change inside a plane when it is opened for paratroopers?&lt;/p&gt;&#xA;" OwnerUserId="3319" LastEditorUserId="4067" LastEditDate="2014-11-04T22:04:37.020" LastActivityDate="2014-11-11T21:08:10.787" Title="Does the pressure change inside a plane when it is opened for paratroopers?" Tags="&lt;aircraft-design&gt;&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9495" PostTypeId="2" ParentId="9494" CreationDate="2014-11-04T21:30:40.437" Score="14" Body="&lt;p&gt;For low deployment the cabin pressure is already equal to the outside pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For High altitude jumps the pressure is reduced to the outside pressure before opening the door (and everyone puts on oxygen masks).&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-11-04T21:30:40.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9496" PostTypeId="2" ParentId="9491" CreationDate="2014-11-04T21:31:38.620" Score="1" Body="&lt;p&gt;From what I can remember of what I've flown, the Cessna 182 was far more quiet/smooth than the 172/other lighter trainers. No clue what the quietist aircraft is, or how nice you can get it. I'm not aware of any aircraft being marketed on it's quiet features. &lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2014-11-04T21:31:38.620" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9497" PostTypeId="1" AcceptedAnswerId="9498" CreationDate="2014-11-04T21:51:10.297" Score="18" ViewCount="20734" Body="&lt;p&gt;A friend of mine is blind in one eye and has normal vision in the other eye.  Would this prevent him from getting a Private Pilots License in the US?&lt;/p&gt;&#xA;" OwnerUserId="526" LastEditorUserId="572" LastEditDate="2015-02-24T10:47:35.637" LastActivityDate="2020-08-31T20:32:29.320" Title="Can you obtain a pilot license with impaired vision / being blind in one eye?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;medical&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9498" PostTypeId="2" ParentId="9497" CreationDate="2014-11-04T22:30:05.627" Score="19" Body="&lt;p&gt;It's possible to get a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/et/31-34/mv/&quot;&gt;special issuance medical certificate in this case&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An applicant will be considered monocular when there is only one eye&#xA;  or when the best corrected distant visual acuity in the poorer eye is&#xA;  no better than 20/200. An individual with one eye, or effective visual&#xA;  acuity equivalent to monocular, may be considered for medical&#xA;  certification, any class, through the special issuance section of part&#xA;  67 (14 CFR 67.401).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="520" LastActivityDate="2014-11-04T22:30:05.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9499" PostTypeId="2" ParentId="9494" CreationDate="2014-11-04T23:09:49.800" Score="14" Body="&lt;p&gt;&lt;strong&gt;It depends!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When people jump off an airplane with parachutes, there are two categories:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Skydiving&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This is normally done at lower altitudes, somewhere from 1,000 meters (3,000 ft) - 4,000 meters (13,000 ft). The airplanes used typically for this purpose do not have a pressurized cabin. So when the door opens for paratroopers to jump, pressure outside is almost the same as inside. After the jump, the door is closed and everyone is happy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a Cessna 208 configured for skydiving, with a door visible on the port side of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tO5xJ.jpg&quot; alt=&quot;Cessna 208&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/High-altitude_military_parachuting&quot; rel=&quot;nofollow noreferrer&quot;&gt;High-altitude military parachuting&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These jumps are done from 4,600 meters (15000 ft) and 11,000 meters (35,000 ft). At 35,000 ft, only 26% of the Oxygen is &lt;a href=&quot;http://www.altitude.org/air_pressure.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;available&lt;/a&gt; when compared to the amount at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the door is opened at such high altitudes, amount of available Oxygen is no longer sufficient for humans and &lt;em&gt;everyone&lt;/em&gt; needs to wear the Oxygen mask to avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Altitude_sickness&quot; rel=&quot;nofollow noreferrer&quot;&gt;sickness due to high altitude&lt;/a&gt;. More about re-pressurization of cabins is discussed &lt;a href=&quot;https://aviation.stackexchange.com/q/8502/65&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the paratroopers are concerned, they wear special gear, which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MtG1M.jpg&quot; alt=&quot;Soldier jumping from high altitude&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-11-11T21:08:10.787" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9500" PostTypeId="1" AcceptedAnswerId="9501" CreationDate="2014-11-04T16:17:42.643" Score="23" ViewCount="18423" Body="&lt;p&gt;I recently flew into Schiphol and experienced a very long taxi time (about 20 minutes) from landing to pulling into the pier at the terminal. Given that the flight was only 90 minutes from closing air plane doors to opening air plane doors. I feel that over 20% of flight time is a little excessive for taxiing at the destination airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I landed in the early evening. Around 19:30 local time with KLM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at a map I think I landed at Polderbaan runway as we crossed a main highway. Possibly the A5.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/w8ANn.png&quot; alt=&quot;Schiphol Map&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: Why does Schiphol build a runway so remote when there is clearly available land nearer to the main airport terminal? And should this runway be used by short haul flights. Should it not be kept for long haul as it is the widest and longest runway at Schiphol?&lt;/p&gt;&#xA;" OwnerUserId="4165" OwnerDisplayName="davidb" LastEditorUserId="3734" LastEditDate="2014-11-05T08:14:45.327" LastActivityDate="2018-03-19T15:41:37.837" Title="Why does Schiphol Airport have such a long taxi?" Tags="&lt;airport-design&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9501" PostTypeId="2" ParentId="9500" CreationDate="2014-11-04T17:39:18.917" Score="33" Body="&lt;p&gt;Schiphol indeed seems to have enough space to build a runway close to the terminal. However it is more the lack of airspace and laws preventing excessive sound levels that made it necessary to create the &quot;polderbaan&quot;. It is also one of the two primary runways for &lt;a href=&quot;https://nl.wikipedia.org/wiki/Polderbaan&quot;&gt;nightflights&lt;/a&gt; (link in Dutch (sorry). Found a reference in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Amsterdam_Airport_Schiphol#Runways&quot;&gt;English wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Newest runway, opened 2003.&#xA;  Located to reduce the noise impact on the surrounding population; aircraft have a lengthy 15-minute taxi to and from the Terminal. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4163" OwnerDisplayName="andra" LastActivityDate="2014-11-04T17:39:18.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9502" PostTypeId="2" ParentId="9500" CreationDate="2014-11-04T23:11:09.107" Score="11" Body="&lt;p&gt;In addition to the noise issue mentioned in andra's answer, the Polderbaan (36L/18R,) Zwanenburgbaan (36C/18C,) and Aalsmeerbaan (36R/18L) runways are parallel. For parallel runways to be used simultaneously (especially if they can all be used for simultaneous arrivals or all used for simultaneous departures,) then there must be a minimum amount of separation between them in order to maintain the required horizontal separation between the air traffic. This may also be part of why the 36L/18R runway is so far away horizontally. An additional factor in the taxi time is that traffic going to or from the 36L/18R runway must taxi around the 36C/18C runway if it is being actively used for an arrival or departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as runways being 'reserved,' most airports don't reserve particular runways for long-haul flights. They may be given preference on a particular runway if it's needed, but that's unlikely to often be the case here, as all three of the parallel runways at Schiphol are sufficiently long for almost any passenger aircraft (they're all over 10,000 ft.)&lt;a href=&quot;http://en.wikipedia.org/wiki/Amsterdam_Airport_Schiphol#Runways&quot;&gt;[1]&lt;/a&gt; In cases of parallel runways that are all sufficiently long, arrival runways are usually assigned more on a basis of which direction the traffic is arriving from than anything else. Which part of the airport the traffic will be taxiing to and how long of a line there is for each runway also may factor into the decision.&lt;/p&gt;&#xA;" OwnerUserId="755" OwnerDisplayName="reirab" LastActivityDate="2014-11-04T23:11:09.107" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9503" PostTypeId="2" ParentId="9479" CreationDate="2014-11-05T09:22:36.150" Score="0" Body="&lt;p&gt;That landing wasn't pretty, but I wouldn't describe it as hard to the point of damaging the aircraft. A bit firm, followed by some oscillation is a better description. Not something that would warrant a maintenance inspection in any case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing about oscillations is that you can often make them worse by using control inputs to even them out. It's usually better to ride them out, which is what looks like is happening in this case. Remember that the aircraft is not out of control just because it bounces. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do enough landings one is eventually going to get ugly even if you've set everything up right. You have a good approach speed, set up a good flare, then suddenly the whole thing drops onto the surface and next thing you know you're skipping down the runway like a flat stone. This is rare in clear air, usually this happens when there is a crosswind which has blown across some structures which have caused pockets of lower air pressure. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-11-05T09:22:36.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9504" PostTypeId="1" AcceptedAnswerId="9509" CreationDate="2014-11-05T09:46:22.617" Score="23" ViewCount="13311" Body="&lt;p&gt;In one of the answers to the question which &lt;a href=&quot;https://aviation.stackexchange.com/questions/9446/oldest-aircraft-still-in-production&quot;&gt;aircraft is the oldest in production&lt;/a&gt;, the &#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;Beechcraft Bonanza&lt;/a&gt; is mentioned. While reading the Wikipedia entry on this interesting plane, I noticed that there are some models with a V-shape tail and some with a more conventional tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between the two designs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XZA6I.jpg&quot; alt=&quot;Bonanza with V-tail&quot;&gt; Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/daGu2.jpg&quot; alt=&quot;Bonanza with conventional tail&quot;&gt; Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="4163" LastEditorUserId="22726" LastEditDate="2019-09-14T01:05:08.587" LastActivityDate="2019-09-14T01:05:08.587" Title="What is the difference between the V-shape tail and the straight tail on the Beechcraft Bonanza?" Tags="&lt;aircraft-design&gt;&lt;v-tail&gt;&lt;beechcraft-bonanza&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9505" PostTypeId="1" AcceptedAnswerId="9510" CreationDate="2014-11-05T10:17:25.870" Score="42" ViewCount="8067" Body="&lt;p&gt;Last week I flew on a modern &lt;a href=&quot;http://www.airliners.net/search/photo.search?cx=partner-pub-8297169501225184%3Aa05n2n-tzky&amp;amp;ie=ISO-8859-1&amp;amp;q=PH-XRD&amp;amp;sa=Submit&amp;amp;search_active=1&amp;amp;search=&amp;amp;sheadline=&amp;amp;search_field=datedesc&amp;amp;submit=&amp;amp;siteurl=www.airliners.net%2F&amp;amp;ref=&amp;amp;ss=0j0j1&quot; rel=&quot;noreferrer&quot;&gt;B737-700&lt;/a&gt;. I noticed that the lavatory was equipped with ashtrays  (both on the inside as on the outside) even with the smoking sign on it. Smoking on airplanes has been banned from quite some time now, so why are lavatories still built where ash trays are provided?&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tLsp8.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="4163" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-04-01T03:18:36.270" Title="Why do lavatories in modern planes still have ash trays?" Tags="&lt;cabin-design&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9506" PostTypeId="2" ParentId="9486" CreationDate="2014-11-05T10:20:29.693" Score="7" Body="&lt;p&gt;Easyjet has no firm weight limit and advertises this fact. From &lt;a href=&quot;http://support.easyjet.com/request.do?view()=c%7b61667aa0-ced8-11e2-ef6e-000000000000%7d&quot; rel=&quot;noreferrer&quot;&gt;the website&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There’s no weight restriction for cabin baggage, as long as you can place and retrieve the cabin bag safely in the overhead lockers without assistance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also use vague language like “within reason” or “lift comfortably” but most people probably won't have 20 kg with them. Given the limited size of cabin luggage, you would need to deliberately carry dense, heavy stuff to reach that weight (books maybe? wine bottles and other liquids are off-limits and if you don't want to check in any bag you still need space for your other things).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then, comes this (from the BA website you mentioned):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Occasionally we may not have space to stow all hand baggage safely on board and you may be asked to check in some or all of your hand baggage at the boarding gate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Bottom line: Airlines don't need to rely on a prespecified weight limit at all. They rely on the size restrictions and general common sense to keep things manageable and if it somehow does not work out, they can always gate check a few bags.&lt;/p&gt;&#xA;" OwnerUserId="3018" LastActivityDate="2014-11-05T10:20:29.693" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9507" PostTypeId="2" ParentId="9504" CreationDate="2014-11-05T10:44:25.110" Score="17" Body="&lt;p&gt;V-tail production ceased in 1982. Possibly due to a perception that they were less safe than a conventional empennage.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The model 35 Bonanza series (1947-1982) had a V-tail&lt;/li&gt;&#xA;&lt;li&gt;The model 36 Bonanza series (1968-present) had a conventional tail.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;There was a self-serving faction in general aviation, though, that went on a crusade to demonize the V-tail because of the in-flight structural failures.&lt;/p&gt;&#xA;&lt;p&gt;Grist for the mill was the fact that Bonanzas with regular tails seldom had structural failures. They did have just as many loss of control accidents. The difference was they were in one piece a millisecond before becoming thousands of pieces after a collision with the ground. The V-tails didn’t make it to the ground in one piece,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://airfactsjournal.com/2012/06/tail-tale-what-was-wrong-with-v-tail-bonanza-pilots/&quot; rel=&quot;noreferrer&quot;&gt;What was wrong with V-tail Bonanza pilots?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-05T10:44:25.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9508" PostTypeId="1" AcceptedAnswerId="9519" CreationDate="2014-11-05T11:15:42.113" Score="9" ViewCount="1264" Body="&lt;p&gt;A question about the &lt;a href=&quot;https://aviation.stackexchange.com/q/9504/1289&quot;&gt;tail shape of the Bonanza&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/9446/1289&quot;&gt;Oldest aircraft still in production&lt;/a&gt; led me to wonder how much the first and latest aircraft in this series actually have in common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1947&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/EKjQG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Rrln5.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.lostflights.com/Historical-Aviation-Accident/February-3-1959-Beechcraft/6477089_25NTGx&quot; rel=&quot;nofollow noreferrer&quot;&gt;lost flights&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2014&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9D3fu.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.beechcraft.com/beechcraft/bonanza_g36/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beechcraft&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/wEMF4.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/September/1/Classically-modern&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearly the following have changed&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;tail design&lt;/li&gt;&#xA;&lt;li&gt;number of windows&lt;/li&gt;&#xA;&lt;li&gt;engines&lt;/li&gt;&#xA;&lt;li&gt;internal arrangements for seating and baggage&lt;/li&gt;&#xA;&lt;li&gt;detailed changes to wing shape&lt;/li&gt;&#xA;&lt;li&gt;cockpit instrumentation&lt;/li&gt;&#xA;&lt;li&gt;cockpit controls&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and many other changes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the basic central-airframe and core-wing design and construction identical?&#xA;Are there any parts in common - or at least directly interchangeable?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="22726" LastEditDate="2019-09-14T22:04:34.600" LastActivityDate="2019-09-14T22:04:34.600" Title="How much do 1947 and 2014 Beechcraft Bonanzas have in common?" Tags="&lt;aircraft-design&gt;&lt;beechcraft-bonanza&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9509" PostTypeId="2" ParentId="9504" CreationDate="2014-11-05T11:23:22.790" Score="35" Body="&lt;p&gt;V-tails have been &lt;a href=&quot;https://en.wikipedia.org/wiki/HKS-1&quot; rel=&quot;noreferrer&quot;&gt;fashionable&lt;/a&gt; in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;Fourties&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Fouga_CM.170_Magister&quot; rel=&quot;noreferrer&quot;&gt;Fifties&lt;/a&gt;, and the claim was that they would cause less drag than an equally effective conventional tail. This has two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Average chord length is longer, so the Reynolds number of the airflow is higher, causing relatively less friction drag.&lt;/li&gt;&#xA;&lt;li&gt;Instead of three surface-fuselage-joints, the V-tail has only two, so less interference drag is created.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wwiiaircraftperformance.org/me109/me109g-14003.html&quot; rel=&quot;noreferrer&quot;&gt;Flight testing of V-tails&lt;/a&gt; showed only marginal advantages, and in damping they are less effective than a conventional tail which is dimensioned for the same control effectiveness. The control effectiveness of a control surface is proportional to the cosine of the V-angle, but the damping characteristics go down with the square of the cosine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@nimbusgb mentions the tendency of the V-tailed Bonanza to fishtail: That is a consequence of too little lateral damping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when a combined elevator-rudder input is commanded, the V-tail will produce a very high deflection on one side, while the two commands will cancel out on the other side. This will reduce overall control power in cases where a combined elevator-rudder input is commanded over what is possible with a conventional tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Standard_Austria&quot; rel=&quot;noreferrer&quot;&gt;glider designers&lt;/a&gt;, who &lt;a href=&quot;https://en.wikipedia.org/wiki/Akaflieg_Braunschweig_SB-5_Danzig&quot; rel=&quot;noreferrer&quot;&gt;had enthusiastically&lt;/a&gt; tried out &lt;a href=&quot;https://en.wikipedia.org/wiki/Glasfl%C3%BCgel_H-101&quot; rel=&quot;noreferrer&quot;&gt;V-tails&lt;/a&gt;, have now returned to conventional tails (more precisely, T-tails) because the expected benefits did not materialize. And glider designers will try anything to improve the aerodynamic quality of their designs.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-05-21T21:28:45.240" LastActivityDate="2017-05-21T21:28:45.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9510" PostTypeId="2" ParentId="9505" CreationDate="2014-11-05T13:17:04.653" Score="39" Body="&lt;p&gt;Because in the US (where Boeings are made) it's required by law. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=0fc12bc109640c17d4907e13ea54c4de&amp;amp;node=se14.1.25_1853&amp;amp;rgn=div8&quot;&gt;14 CFR 25.853(g)&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(g) Regardless of whether smoking is allowed in any other part of the&#xA;  airplane, lavatories must have self-contained, removable ashtrays&#xA;  located conspicuously on or near the entry side of each lavatory door,&#xA;  except that one ashtray may serve more than one lavatory door if the&#xA;  ashtray can be seen readily from the cabin side of each lavatory&#xA;  served.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The law may be different in other jurisdictions, of course. &lt;em&gt;Why&lt;/em&gt; the law still exists is another question, but either no one found the time to change it (laws are often very difficult to change once passed) or it was a deliberate decision to keep requiring ashtrays in case someone tries to smoke anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; As commenters have noted, the law I quoted requires ashtrays &lt;em&gt;outside&lt;/em&gt; the lavatories but it's still common to find them &lt;em&gt;inside&lt;/em&gt;. My guess here is that the ones outside comply with the &lt;em&gt;letter&lt;/em&gt; of the law, whereas the ones inside comply with the &lt;em&gt;intent&lt;/em&gt;, i.e. they're there because if someone does light up, it will be inside the lavatory and not outside in plain view. &lt;a href=&quot;http://www.cntraveler.com/stories/2012-08-14/airplane-bathroom-ash-trays-explained&quot;&gt;This 2012 article&lt;/a&gt; quotes an anonymous FAA source as saying that people continue to smoke on aircraft so it still makes sense to have them for safety reasons. That raises the question (again) of why the law doesn't fully reflect reality, but that's neither unusual nor unique to aviation.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-05T15:04:27.383" LastActivityDate="2014-11-05T15:04:27.383" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9511" PostTypeId="1" AcceptedAnswerId="9514" CreationDate="2014-11-05T14:07:51.173" Score="7" ViewCount="2791" Body="&lt;p&gt;What is the maximum altitude I'm allowed to fly a model plane or helicopter in England?&lt;/p&gt;&#xA;" OwnerUserId="3314" LastEditorUserId="19" LastEditDate="2015-01-12T20:07:30.763" LastActivityDate="2015-01-12T20:07:30.763" Title="What is the maximum altitude allowed to fly a model plane/helicopter in England?" Tags="&lt;altitude&gt;&lt;model-aircraft&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9512" PostTypeId="2" ParentId="9491" CreationDate="2014-11-05T14:53:01.093" Score="11" Body="&lt;p&gt;I assume that you're asking about piston engine light aircraft, so we can ignore gliders and electric engines for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic point is that they're all loud. &lt;a href=&quot;http://ohsonline.com/articles/2010/07/12/interior-sound-levels-in-general-aviation-aircraft.aspx&quot;&gt;One study&lt;/a&gt; compared a Cessna 172 (single engine) and a Piper Seminole (twin engine) and found that the average cabin noise was around 86 &lt;a href=&quot;http://en.wikipedia.org/wiki/Decibel&quot;&gt;decibels&lt;/a&gt;, with no huge difference between the two aircraft. There's more analysis of a Seminole &lt;a href=&quot;https://bib.irb.hr/datoteka/482262.EAA-EUROREGIO-173.pdf.pdf&quot;&gt;here&lt;/a&gt;. The FAA &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/hearing_brochure.pdf&quot;&gt;says&lt;/a&gt; that a light aircraft cabin is in the range of 70-90dB and &lt;a href=&quot;http://philip.greenspun.com/flying/cirrus-sr20&quot;&gt;this Cirrus owner&lt;/a&gt; measured 92-98dB in different Cirrus models. &lt;a href=&quot;https://www.osha.gov/&quot;&gt;OSHA&lt;/a&gt; in the US &lt;a href=&quot;https://www.osha.gov/SLTC/noisehearingconservation/&quot;&gt;requires&lt;/a&gt; ear protection and other measures for workers if the noise in their environment is 85dB or more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since decibels are on a logarithmic scale, the difference between 86dB and 98dB is large. But I searched a few aviation forums and there's very little discussion of cabin noise in light singles apart from a few subjective remarks. I couldn't find any good sources that said one aircraft type is well known as being noisier or quieter than average. The only consistent comment is that helicopters are louder than fixed-wing aircraft, which is also shown in the FAA document linked above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, there are quite a few articles online about soundproofing aircraft in different ways. &lt;a href=&quot;http://www.wolf-aviation.org/aircraft_noise.htm&quot;&gt;This one&lt;/a&gt; quotes the example of a jet:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aero Sound Shield is currently soundproofing a particularly large&#xA;  corporate jet - a converted McDonnell-Douglas MD-87 - for a Las Vegas&#xA;  hotel owner who is almost totally blind and who has compensated by&#xA;  developing extremely sensitive hearing. &quot;He wants a 60-dB airplane,&#xA;  which is quieter than a Lexus,&quot; Nelson points out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the same article makes the point that modifying &lt;em&gt;any&lt;/em&gt; aircraft to add soundproofing increases the weight to a point that makes the aircraft much less useful:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unfortunately, your airplane and mine can't accept the mass and weight&#xA;  of MD-87 measures. &quot;I rode one time in a Piper Arrow that was very&#xA;  quiet,&quot; Nelson recalls, &quot;but it was completely lead-lined. It could&#xA;  carry two people and half a load of fuel. That was fine for that guy,&#xA;  because that's all he ever wanted to carry, but it wasn't very&#xA;  practical.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Furthermore, it's worth remembering that modern noise-cancelling headsets are very good so the problem of noise (as opposed to vibration, which is also a factor for fatigue and health) has been more or less solved for most people. Even if you spend $1000 or more on a high-end ANR headset, that's a minor cost compared to altering the aircraft structure or materials and you still have full performance and useful load. I guess that for most GA pilots that's the decisive factor.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-05T15:43:20.953" LastActivityDate="2014-11-05T15:43:20.953" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9513" PostTypeId="2" ParentId="9505" CreationDate="2014-11-05T14:59:07.830" Score="5" Body="&lt;p&gt;&quot;One size fits all&quot;.  Since smoking is/may be allowed on some foreign airlines, it would be silly for Boeing and other manufacturers to build airliners that were smoker-equipped and those for non-smoking. It is easier and less costly to install ashtrays on all aircraft and just keep the no smoking light on for those flights where smoking is prohibited.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-11-05T14:59:07.830" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9514" PostTypeId="2" ParentId="9511" CreationDate="2014-11-05T15:39:21.440" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP658%204%20Edition%20Amend%201%20June%202013.pdf&quot; rel=&quot;noreferrer&quot;&gt;According to the UK CAA&lt;/a&gt;, a model aircraft is defined as: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;any ‘Small Unmanned Aircraft (SUA)’ (0-20 kg) used for sporting and&#xA;  recreational purposes and a ‘large model aircraft’ is defined as any&#xA;  ‘Unmanned Aircraft’ (over 20 kg) used for sporting and recreational&#xA;  purposes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The following rule applies to all &quot;small unmanned aircraft&quot;, i.e. up to 20kg:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) The person in charge of a small unmanned aircraft &lt;strong&gt;must maintain&#xA;  direct, unaided visual contact with the aircraft&lt;/strong&gt; sufficient to monitor&#xA;  its flight path in relation to other aircraft, persons, vehicles,&#xA;  vessels and structures for the purpose of avoiding collisions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The following rule applies between 7kg and 20kg only:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The person in charge of a small unmanned aircraft which has a mass of&#xA;  more than 7 kg excluding its fuel but including any articles or&#xA;  equipment installed in or attached to the aircraft at the commencement&#xA;  of its flight, must not fly the aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) in Class A, C, D or E airspace unless the permission of the&#xA;  appropriate air traffic control unit has been obtained;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) within an aerodrome traffic zone during the notified hours of&#xA;  watch of the air traffic control unit (if any) at that aerodrome&#xA;  unless the permission of any such air traffic control unit has been&#xA;  obtained; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) at a height of more than 400 feet above the surface unless it is&#xA;  flying in airspace described in sub-paragraph (a) or (b) and in&#xA;  accordance with the requirements for that airspace&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So in theory, a model aircraft weighing less than 7kg could be flown to any altitude, with the only limitation being the requirement to keep in it sight. From 7kg to 20kg the altitude is 400ft, unless you meet the airspace requirements. In practical terms, the requirement to keep the aircraft in sight &quot;unaided&quot; is the main limitation and that restricts the altitude of smaller models in particular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's over 20kg, the model aircraft is subject to all the regular UK aviation rules but in practice a written exemption is required:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Large model aircraft having a mass between 20 kg and 150 kg are&#xA;  subject to all of the Rules or Articles of the Air Navigation Order.&#xA;  As many of these Rules are practically impossible for the model&#xA;  operator to meet, the modeller must request a specific written&#xA;  Exemption to allow the model to be flown&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The CAA homepage for model aircraft is &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=1416&amp;amp;pageid=8153&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-06T13:57:15.500" LastActivityDate="2014-11-06T13:57:15.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9516" PostTypeId="1" AcceptedAnswerId="9552" CreationDate="2014-11-05T16:00:36.713" Score="7" ViewCount="1436" Body="&lt;p&gt;When reading the following comment on question &lt;a href=&quot;https://aviation.stackexchange.com/questions/9505/why-do-lavatories-in-modern-planes-still-have-ash-trays&quot;&gt;&quot;Why do lavatories in modern planes still have ash trays?&lt;/a&gt;&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9505/why-do-lavatories-in-modern-planes-still-have-ash-trays/9513#comment17817_9513&quot;&gt;Andra: November 05 2014 at 16:00&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have flown on an Embraer 195 where the no-smoking sign was replaced by a no-electronics sign&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the reason for exchanging the non-smoking sign with a &quot;Please Turn Off Electronic Devices&quot; sign? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Of course Smoking is prohibited on all flights around the globe, so&#xA;the answer where the comment is, is untrue. But was this sign unnecessary&#xA;because everybody knows it's prohibited?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MjPrS.jpg&quot; alt=&quot;Please Turn Off Electronic Devices&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-01-22T07:51:37.103" Title="What was the reason for replacing the non-smoking sign with a &quot;no electronics&quot; sign?" Tags="&lt;cabin-design&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9518" PostTypeId="2" ParentId="9505" CreationDate="2014-11-05T19:04:17.940" Score="24" Body="&lt;p&gt;It's for safety.  Smoking may be prohibited, but if a passenger smokes anyway, you don't want the remains of the cigarette to start a fire due to improper disposal, as probably happened with &lt;a href=&quot;http://en.wikipedia.org/wiki/Varig_Flight_820&quot;&gt;Varig Flight 820&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A possible cause of the fire was that the lavatory waste bin contents caught fire after a still lit cigarette was thrown into it, the FAA issued AD 74-08-09 requiring &quot;installation of placards prohibiting smoking in the lavatory and disposal of cigarettes in the lavatory waste receptacles; establishment of a procedure to announce to airplane occupants that smoking is prohibited in the lavatories; installation of ashtrays at certain locations; and repetitive inspections to ensure that lavatory waste receptacle doors operate correctly&quot;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is the latest revision of &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/4F81F7ED5A921083862579AC005B367E?OpenDocument&quot;&gt;FAA Airworthiness Directive 74-08-09&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="487" LastEditorUserId="487" LastEditDate="2014-11-05T19:12:47.577" LastActivityDate="2014-11-05T19:12:47.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9519" PostTypeId="2" ParentId="9508" CreationDate="2014-11-05T19:10:31.290" Score="16" Body="&lt;p&gt;The V-Tail Bonanza design was retired (for a bunch of reasons, many of them marketing-related), but the actual airframe of a modern Beech 36 Bonanza is, essentially, the same as the 1968 Beech 36 (and very similar to the 1959 Debonair, just stretched). You can trace a great deal of the design and parts back to the V-tail as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been some changes made to the design over the years (for example, the throw-over yoke is gone, replaced by conventional dual controls), but the bulk of the airframe parts are interchangeable because the designs are essentially the same (this is an advantage for Beech owners: The factory is still producing nearly all the parts you'll need for maintenance, because they need them to put in the new planes).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Most of the light GA aircraft produced by the legacy manufacturers (Beech, Cessna, Piper) are what are known as &quot;follow-on type certificate models&quot; -- they are the same production design approved back in the 1950s/1960s, with &quot;minor&quot; changes incorporated along the way. This means you'll find the same kind of parts continuity in pretty much all the major manufacturer's aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most of the parts on a 1960s Cherokee 180 are the same parts you'll find in a 2014 Archer III (changes to the airfoil and panel layout notwithstanding)&lt;/li&gt;&#xA;&lt;li&gt;Many of the parts on a modern Cessna 172S are the same as the 1965 172F (the year they went to electric flaps).&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You'll find many common parts on the 172 going back all the way to the original 1956 172 if you look. Big changes were the swept-back tail fin (1960) and the electric flaps (1965)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-05T19:10:31.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9521" PostTypeId="1" AcceptedAnswerId="9522" CreationDate="2014-11-05T19:46:31.120" Score="23" ViewCount="5298" Body="&lt;p&gt;Today is a day when I feel terribly tired. I'm not ill, but I could sleep all the day, though I had enough sleep last night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not a problem if you have an office job where you can probably be not as productive than on other days. But what about pilots? They are expected to have a high level of concentration and vigilance during the whole flight? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question, &lt;a href=&quot;https://aviation.stackexchange.com/q/443/65&quot;&gt;&lt;em&gt;What should a pilot do if they feel sleepy?&lt;/em&gt;&lt;/a&gt; concentrates more on upcoming sleepiness during the flight. The &lt;a href=&quot;https://aviation.stackexchange.com/a/450/65&quot;&gt;accepted answer&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a pilot is not rested enough to safely operate the aircraft, they should not fly. [...] &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, &quot;should not&quot; sounds more like  advice than a rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may say that there are always two pilots on (not so long) commercial flights, but then you can also start with one faulty engine, because the second engine still could bring you to your destination. For me, this breaks the safety concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, can a pilot go to a doctor and tell, &quot;I'm tired today so I can't work&quot;?&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2017-03-09T02:37:16.253" Title="What if pilot feels too tired before his flight?" Tags="&lt;safety&gt;&lt;pilots&gt;&lt;human-factors&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9522" PostTypeId="2" ParentId="9521" CreationDate="2014-11-05T21:16:01.277" Score="19" Body="&lt;p&gt;So if you are well rested and not ill, but still feeling tired, there has to be something else wrong. From your description, it appears to be &lt;a href=&quot;http://en.wikipedia.org/wiki/Fatigue_(safety)#In_aviation&quot;&gt;fatigue&lt;/a&gt;. The common signs for fatigue are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Falling asleep&lt;/li&gt;&#xA;&lt;li&gt;Yawning&lt;/li&gt;&#xA;&lt;li&gt;Poor visual acuity&lt;/li&gt;&#xA;&lt;li&gt;Feeling &quot;sluggish&quot; or &quot;drowsy&quot;&lt;/li&gt;&#xA;&lt;li&gt;Decreased reaction time&lt;/li&gt;&#xA;&lt;li&gt;Decreased concentration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Although, the most commonly known reason for fatigue is lack of sleep, but any or all of the following can cause fatigue:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lack of quality sleep&lt;/li&gt;&#xA;&lt;li&gt;Sleep disturbances&lt;/li&gt;&#xA;&lt;li&gt;Interruption of circadian rhythm&lt;/li&gt;&#xA;&lt;li&gt;Mental or emotional stress&lt;/li&gt;&#xA;&lt;li&gt;Physical exertion, such as heavy exercise&lt;/li&gt;&#xA;&lt;li&gt;Poor health, including dehydration or poor diet&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Pilots can assess their own fitness to fly by the &lt;a href=&quot;http://en.wikipedia.org/wiki/IMSAFE&quot;&gt;IMSAFE&lt;/a&gt; mnemonic. FAA has a small &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Fatigue_Aviation.pdf&quot;&gt;handout&lt;/a&gt; about fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now what pilots (and generalizing, people) can do and actually do are two very different aspects. A &lt;a href=&quot;http://dead-tired.eu/pilot-fatigue/facts/surveys-pilot-fatigue&quot;&gt;survey&lt;/a&gt; about European pilots mention:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... many are afraid their fatigue reports could have negative&#xA;  consequences for their professional future (i.e. reprisals by&#xA;  management) ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA has &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=13272&quot;&gt;a new rule&lt;/a&gt; which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA expects pilots and airlines to take joint responsibility when&#xA;  considering if a pilot is fit for duty, including fatigue resulting&#xA;  from pre-duty activities such as commuting.  At the beginning of each&#xA;  flight segment, a pilot is required to affirmatively state his or her&#xA;  fitness for duty.  If a pilot reports he or she is fatigued and unfit&#xA;  for duty, the airline must remove that pilot from duty immediately.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer to your question is: &lt;strong&gt;Yes, they can!&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-11-05T21:16:01.277" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9523" PostTypeId="2" ParentId="9521" CreationDate="2014-11-05T21:22:12.313" Score="8" Body="&lt;p&gt;&lt;em&gt;&quot;So, does a pilot go to the doctor and say &quot;I'm tired today, I can't work&quot;?&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simply put, &lt;strong&gt;&quot;Yes.  Say you cannot work.&quot;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a surgeon cannot operate with full facilities, he doesn't operate.&#xA;The patient can have surgery tomorrow (in most cases).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot cannot be assured that he can perform, regardless of weather, mechanical issues, ATC delays, whatever, the passengers can be inconvenienced.&lt;br&gt;It is better than the alternative, which is &lt;a href=&quot;http://en.wikipedia.org/wiki/Colgan_Air_Flight_3407&quot;&gt;ending up dead&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-11-05T21:22:12.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9524" PostTypeId="2" ParentId="9504" CreationDate="2014-11-05T22:11:07.970" Score="6" Body="&lt;p&gt;The technical stuff in other answers is right. The other difference is that the V-tailed Bonanza's tended to 'fishtail' slightly in the cruise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I recall correctly, V-tails are not as spin resistant as conventional tails. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My dad flew a Standard Austria for a time (early V-tail sailplane) and it was very definitely prohibited from intentional spinning. Dad tried it once and told me it took about three turns before it would recover.&lt;/p&gt;&#xA;" OwnerUserId="1304" LastEditorUserId="65" LastEditDate="2014-11-06T12:35:06.027" LastActivityDate="2014-11-06T12:35:06.027" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9525" PostTypeId="1" AcceptedAnswerId="9528" CreationDate="2014-11-06T02:04:41.137" Score="48" ViewCount="84777" Body="&lt;p&gt;Why did the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_87&quot;&gt;Ju-87 Stuka&lt;/a&gt; have a siren? Was this for purely psychological reasons or did it help the pilot in some way?&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="22726" LastEditDate="2020-02-22T22:55:29.820" LastActivityDate="2020-02-22T22:55:29.820" Title="Why did the Ju-87 Stuka have a siren?" Tags="&lt;aviation-history&gt;&lt;bomber&gt;&lt;ju-87&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9526" PostTypeId="1" CreationDate="2014-11-06T06:53:58.487" Score="13" ViewCount="24867" Body="&lt;p&gt;I understand that, to increase the thrust of a turbojet engine in flight, it is necessary to increase fuel mass flow rate. This throttling then increases the exit velocity of air and gives increased thrust (if this was wrong, please also explain how is the thrust practically changed in cruise).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the engine RPM vary in this process?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an equation which binds together spool RPM to the thrust?&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="19" LastEditDate="2015-01-09T12:04:31.533" LastActivityDate="2017-01-24T12:48:34.563" Title="What is the relationship between thrust and engine RPM in a turbojet?" Tags="&lt;jet-engine&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9527" PostTypeId="2" ParentId="9525" CreationDate="2014-11-06T08:18:58.170" Score="27" Body="&lt;p&gt;The psychology behind it helped the pilot ... panicking enemies doesn't make for very good shots, they're more likely to miss you. They're also more likely to just drop flat on the ground rather than dive into cover or try to shoot back at you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that was pretty much the idea. Get the enemies to become disoriented, panicky, so they're less efficient fighters and easier to defeat by both you and the ground forces you're supporting.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="65" LastEditDate="2014-11-06T14:57:43.633" LastActivityDate="2014-11-06T14:57:43.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9528" PostTypeId="2" ParentId="9525" CreationDate="2014-11-06T09:55:59.240" Score="48" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_87#Ju_87B&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The B-1 [variant] was also fitted with &quot;Jericho trumpets&quot;, essentially propeller-driven sirens with a diameter of 0.7 m (2.3 ft) mounted on the wing's leading edge directly forward of the landing gear, or on the front edge of the fixed main gear fairing. This was used to weaken enemy morale and enhance the intimidation of dive-bombing. After the enemy became used to it, however, they were withdrawn. The devices caused a loss of some 20–25 km/h (10-20 mph) through drag. Instead, some bombs were fitted with whistles on the fin to produce the noise after release.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, yes, it was purely psychological and actually &lt;em&gt;hindered&lt;/em&gt; the pilot by reducing air speed in ordinary flight and they were removed when they stopped having the psychological effect.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2014-11-07T09:09:09.180" LastActivityDate="2014-11-07T09:09:09.180" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9529" PostTypeId="1" AcceptedAnswerId="13420" CreationDate="2014-11-06T12:00:58.580" Score="8" ViewCount="2096" Body="&lt;p&gt;Is there an encoding system that replaces the vagueness of natural language when it comes to logging aircraft problems or repairs that took place at a specific site on the airplane? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, instead of someone having to enter a description like:&#xA;&quot;Hydraulic fluid change at system ABC&quot;&#xA;Which would be in their own native language and filtered by their own personal level of awareness, they could enter something like:&#xA;&quot;GF65Z ABC&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, internationally, GF65Z could correspond to exactly that type of intervention with some hydraulic system and that would also make further investigation, in the case of some problem, easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anywhere I can find more information about something like this?&lt;/p&gt;&#xA;" OwnerUserId="4181" LastActivityDate="2015-03-24T04:24:51.273" Title="How do engineers log airplane maintenance?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9530" PostTypeId="2" ParentId="9529" CreationDate="2014-11-06T12:11:55.207" Score="14" Body="&lt;p&gt;Natural language is concrete enough for this purpose, the logs aren't meant for machine parsing but instead for pilots, inspectors and other mechanics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having such a code system requires mechanics to memorize all of the codes or have a massive list handy when filling out the logs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also making such an international code system requires agencies of all countries/manufacturers to sit together and set those codes for &lt;em&gt;all&lt;/em&gt; possible maintenance actions. There is a very high chance an action will be missed so a natural language box for &quot;additional comments&quot; is still required. It also needs to be rolled out to the actual mechanics filling out the logs.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-11-06T12:11:55.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9531" PostTypeId="2" ParentId="9526" CreationDate="2014-11-06T12:12:19.920" Score="13" Body="&lt;p&gt;First, lets see how thrust works. &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/specth.html&quot;&gt;NASA explains it pretty good.&lt;/a&gt; They conclude that for turbo-fan engines &quot;specific thrust [...] depends only on the velocity difference produced by the engine.&quot; If you think about it, velocity difference in a gas is &lt;a href=&quot;http://en.wikipedia.org/wiki/Dynamic_pressure&quot;&gt;dynamic pressure.&lt;/a&gt; So, how much thrust the engine will generate depends on how big of a dynamic pressure difference it can create in the air between its front and back. A turbo-fan engine creates this pressure difference in two ways. One is by using a fan to &quot;push&quot; air to the back. The other one is by heating up the air that passes through its burner and shooting it out of the nozzle (after passing it first from the turbine.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, on to your question. We need to see if added RPM creates added thrust (or if more thrust needs more RPM.) The answer is that, yes it does. Providing the engine with more fuel will create faster escaping hot gasses from the burner. Those will create a bigger dynamic pressure difference between the burner and the nozzle and the turbine will turn faster. Power from the turbine is moved to the fan which will also turn faster thus pushing out more air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Refer to &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/epr.html&quot;&gt;here&lt;/a&gt; for a graphical description of the engine compartments and how pressure is formed between them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How RPM and total thrust for a model turbo-fan engine are related is graphed on &lt;a href=&quot;http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/537.PDF&quot;&gt;page four and seven of this document&lt;/a&gt;. There you can also find various equations that describe those graphs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: A turbo-jet engine works pretty much the same but instead of using the power generated from the turbine to mainly move the fan, it uses it to move only the compressor. All its thrust is generated from the hot gasses coming out of the nozzle.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="2122" LastEditDate="2014-11-06T12:18:57.890" LastActivityDate="2014-11-06T12:18:57.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9532" PostTypeId="2" ParentId="9526" CreationDate="2014-11-06T14:39:38.940" Score="4" Body="&lt;p&gt;A turbojet works by compressing air, heating the compressed air while keeping pressure almost constant, and running this heated air through a turbine which will  expand it again. The work done while expanding air in the turbine is needed to run the compressor, and the heating in the middle is needed to add enough energy so the turbine will spin and the gas leaving the engine will still have more impulse/momentum (speed times mass) than the air which entered the compressor. At the end of this process, the air leaving the turbine will turn the remaining pressure into speed in the exhaust nozzle, so the gasses leave the engine at a higher speed, but the same pressure with which they entered the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding more fuel to the combustion will increase the heat and speed of the gasses entering the turbine, so more work can be done here. This excess work will speed up the turbine, and with it the compressor, so more air gets pumped into the combustion process, until a new balance has been attained where the heat energy added in the combustion will just be enough to keep the engine spinning at its new speed. RPM and fuel flow go up and down together, but within strict limits and not linearly. Increasing fuel flow when the intake cannot provide more air, or increasing it too quickly to allow for spinup, will lead to a &lt;a href=&quot;http://en.wikipedia.org/wiki/Compressor_stall&quot; rel=&quot;nofollow&quot;&gt;compressor surge&lt;/a&gt;, flow separates at the compressor blades and mass flow through the compressor collapses. Shortly after, the turbine will start to melt from the excessive gas temperature. To avoid improper throttle commands, modern jet engines are filtering commands through a &lt;a href=&quot;http://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;computerized control system&lt;/a&gt;, so the pilot has fewer opportunities to screw up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every stage of the compressor adds a pressure increase, and faster rotation speed means more air throughput and an increased compression ratio. By spinning faster, the compressor can increase the pressure in the combustion chamber and increase mass flow, diluting the fuel-air mixture. Now the air entering the turbine flows faster but is cooler, because the same amount of fuel has to heat up a higher air mass per time. The turbine works like a compressor in reverse: After each turbine stage the air is expanded and cooler than when it entered this stage. The turbine will spin as fast as the energy given off in the expansion process allows it to turn the compressor, and the mass flow and entry temperature determine how much energy is available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotation speed of the turbine at idle is roughly 50% of the speed at full thrust. The relation between thrust and RPM is rather complex, if you want to study it, I recommend simulation software like &lt;a href=&quot;http://www.gasturb.de/software.html&quot; rel=&quot;nofollow&quot;&gt;GasTurb&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-07T07:25:19.987" LastActivityDate="2014-11-07T07:25:19.987" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9533" PostTypeId="1" CreationDate="2014-11-06T15:21:50.967" Score="6" ViewCount="4824" Body="&lt;p&gt;On my radio, an ICOM A210, I can't tune 121.62 (the clearance delivery frequency at &lt;a href=&quot;http://en.wikipedia.org/wiki/Dane_County_Regional_Airport&quot; rel=&quot;noreferrer&quot;&gt;KMSN&lt;/a&gt;). How can I tune a frequency ending in 2?&lt;/p&gt;&#xA;" OwnerUserId="4182" LastEditorUserId="62" LastEditDate="2014-11-07T18:06:53.840" LastActivityDate="2017-06-26T21:22:44.633" Title="How can I tune a frequency like 121.62 on a comm radio?" Tags="&lt;radio-communications&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9534" PostTypeId="1" CreationDate="2014-11-06T16:06:14.467" Score="3" ViewCount="3114" Body="&lt;p&gt;&lt;a href=&quot;http://www.youtube.com/watch?v=On8dnGJu9oY&quot; rel=&quot;nofollow&quot;&gt;Watching this video&lt;/a&gt;, I was wondering, does the Toilet paper have this much lift, because I think the descent speed of the Airplane is not that much?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I don't think that a parachute-plane can catch up with a person in&#xA;free-fall?&lt;/li&gt;&#xA;&lt;li&gt;Can somebody explain me physical how this maneuver works?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="62" LastEditDate="2014-11-06T19:12:24.550" LastActivityDate="2014-11-06T21:44:40.913" Title="How can an airplane descend faster than a free-falling roll of toilet paper?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;airshow&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9535" PostTypeId="1" AcceptedAnswerId="9539" CreationDate="2014-11-06T16:11:45.303" Score="21" ViewCount="6301" Body="&lt;p&gt;How do helicopters approach and land at an airport? Do they use the same general traffic pattern as fixed-wing aircraft?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="247" LastEditDate="2014-11-07T11:46:57.283" LastActivityDate="2018-05-29T06:56:34.510" Title="Do helicopters fly a standard pattern before landing?" Tags="&lt;landing&gt;&lt;helicopter&gt;&lt;approach&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9536" PostTypeId="2" ParentId="9534" CreationDate="2014-11-06T16:24:23.687" Score="13" Body="&lt;p&gt;&lt;em&gt;&quot;I think the descent speed of the airplane is not that much&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think you are wrong.  Airplanes can descend very rapidly when needed.&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane is aerodynamic, meaning it slices through the air nicely, whether it is flying straight-and-level, or aiming straight for the ground.  So its free-fall speed is much higher than that of a roll of paper, which will have considerable wind resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, the airplane has a propeller, which adds force.  When in a dive, the airplane has gravity &lt;strong&gt;&lt;em&gt;plus&lt;/em&gt;&lt;/strong&gt; the force of the propeller taking down.  But the roll of paper only has gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect that in a full dive, the airplane could probably exceed a 10,000 FPM descent, or around 120MPH, which is around the terminal velocity of a skydiver.&lt;br&gt;&#xA;(pulling out of a full dive safely is not easy, however).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The roll of paper will obviously and intuitively be slower than a skydiver.&lt;br&gt;&#xA;I estimate it to be no more than 2,000 FPM, or about 20 MPH. (and probably a bit less)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;(edit: In the comments, Henning Makholm suggests that a paper roll may only fall at 200 FPM. That is less than 3 MPH, which seems a bit slow to me.   A &lt;strong&gt;slow&lt;/strong&gt; descent rate for a Cessna when approaching an airport is 500 FPM.)&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The airplane does not even need to enter a full dive to be faster than the paper. It could probably catch the paper with a nice, gentle 2,500 or 3,000 FPM descent.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-11-06T21:44:40.913" LastActivityDate="2014-11-06T21:44:40.913" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9537" PostTypeId="2" ParentId="9535" CreationDate="2014-11-06T16:28:21.303" Score="11" Body="&lt;p&gt;They won't come in at altitude and then descend vertically until touch down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major reason is that rapid vertical descent has the danger that the rotor could end up in its own downwash and lose most of its lift. You don't want that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what they will do is come in horizontally while descending until over the landing site only a few dozen feet from the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports generally have specific landing pads for VTOL capable aircraft (like helicopters), so they will direct them there instead of the runway.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-11-06T21:44:59.130" LastActivityDate="2014-11-06T21:44:59.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9538" PostTypeId="2" ParentId="9533" CreationDate="2014-11-06T16:51:52.673" Score="21" Body="&lt;p&gt;As a complete guess, you're trying to tune 121.620, but you should just be tuning 121.625. &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2008/August/200808_Features_Frequent_Frequencies.html&quot; rel=&quot;noreferrer&quot;&gt;From AOPA&lt;/a&gt; (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All aviation communication, VOR, and ILS frequencies are in the 100&#xA;  MHz band, so the first number is always &quot;1.&quot; The hundredths digit can&#xA;  be only 0, 2, 5, or 7; &lt;strong&gt;1xx.x2 implies 1xx.x25&lt;/strong&gt;; and 1xx.x7 implies&#xA;  1xx.x75--when a frequency is assigned, the ending &quot;5&quot; is often&#xA;  omitted. Trailing zeros in the hundreds and thousandths positions are&#xA;  always omitted in voice transmissions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The standard frequency spacing in the US is 25kHz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Omitting the last digit is also described in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0204.html&quot; rel=&quot;noreferrer&quot;&gt;FAA's ATC instructions&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The separate digits of the frequency, inserting the word “point” where the decimal point occurs.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(a) Omit digits after the second digit to the right of the decimal&#xA;  point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They include this example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;135.275 MHz “One three five point two seven.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And although this probably isn't your issue, it's worth noting that some radios tune in 50kHz increments by default, unless you pull out (usually) the tuning knob to enable 25kHz tuning. I've been momentarily confused by that several times in unfamiliar aircraft. I assume this isn't the issue you have, though, since the &lt;a href=&quot;http://www.icomamerica.com/en/downloads/DownloadDetails.aspx?Document=324&quot; rel=&quot;noreferrer&quot;&gt;manual&lt;/a&gt; for the A210 says it uses 25kHz spacing.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-06-26T21:22:44.633" LastActivityDate="2017-06-26T21:22:44.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9539" PostTypeId="2" ParentId="9535" CreationDate="2014-11-06T17:08:31.540" Score="23" Body="&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim&quot; rel=&quot;noreferrer&quot;&gt;FAA AIM&lt;/a&gt;, in &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0403.html#aim0403.html.17&quot; rel=&quot;noreferrer&quot;&gt;4-3-17&lt;/a&gt; and the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0311.html&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Controller Handbook, Section 11&lt;/a&gt;, explains VFR helicopter operations at controlled airports. The procedure will depend on the airport and the current traffic.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Insofar as possible, helicopter operations will be instructed to avoid the flow of fixed-wing aircraft to minimize overall delays; however, there will be many situations where faster/larger helicopters may be integrated with fixed-wing aircraft for the benefit of all concerned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Helicopters may operate from a designated helicopter landing area. The tower is responsible for separating them from other traffic. The helicopter can fly a much closer pattern than other aircraft, and may stay on the other side of the runway from the typical pattern. They may also operate straight in/out of the landing area, depending on wind and traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They may also be cleared to take off or land in a &quot;nonmovement&quot; area that is not specifically designated for that activity, which could be a ramp at the airport or a location off-airport. This will be up to the tower to provide clearance and the pilot to execute safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters can also operate similarly to fixed-wing aircraft, taking off and landing using a runway, and following taxiways. Wheeled helicopters taxi on the ground. Otherwise, helicopters may either &lt;em&gt;hover taxi&lt;/em&gt;, where they fly in ground effect at low speed, or &lt;em&gt;air taxi&lt;/em&gt;, where they will fly out of ground effect up to 100 ft AGL and up to 60 kts, as directly as possible to the next point on the field, avoiding obstacles as needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like ratchet freak says, they will generally come in horizontally while descending, flying into the wind, and then come into hover, where they will then be instructed by the tower to taxi to wherever they are going on the field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports, like in this photo of &quot;spot Charlie&quot; on &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/5/53/HWD_-_FAA_airport_diagram.gif&quot; rel=&quot;noreferrer&quot;&gt;Taxiway Zulu at Hayward Aiport&lt;/a&gt;, may have marked spots on the taxiways or non-movement areas for helicopter operations. In this case, students practicing landings and autorotations will be instructed: &quot;Clear to land, Spot Charlie&quot; to keep them off of the main runway 28L, while in left traffic on the opposite side of the runway of the smaller 28R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ND53T.png&quot; alt=&quot;Spot Charlie&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with any aircraft, the final authority for safety is the pilot, and they must be aware of their limitations and the conditions around them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At non-towered airports, the procedures can be similar. The pilot should take the wind direction and traffic into account, and announce their intentions on the appropriate frequency.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="3504" LastEditDate="2015-01-04T17:00:29.070" LastActivityDate="2015-01-04T17:00:29.070" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9540" PostTypeId="2" ParentId="9533" CreationDate="2014-11-06T17:10:55.243" Score="4" Body="&lt;p&gt;I called &lt;a href=&quot;http://en.wikipedia.org/wiki/Dane_County_Regional_Airport&quot; rel=&quot;nofollow&quot;&gt;KMSN&lt;/a&gt; tower, they said 121.625 should work as well or, just call ground which is what I did last time I was there.&lt;/p&gt;&#xA;" OwnerUserId="4185" LastEditorUserId="65" LastEditDate="2014-11-06T17:56:00.137" LastActivityDate="2014-11-06T17:56:00.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9541" PostTypeId="2" ParentId="9494" CreationDate="2014-11-06T18:17:41.220" Score="2" Body="&lt;p&gt;&lt;strong&gt;It does.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you open the door, Bernoulli's principle guarantees the pressure in the cabin will drop (yes, lower than outside).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual pressure difference will depend on various factors like door placement and size, aircraft slip, but mostly and especially on aircraft speed. For a normal skydiving operating speed (say &amp;lt;100kts) this will raise the cabin altitude by no more than 100-200 feet. &lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-11-06T18:17:41.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9543" PostTypeId="1" AcceptedAnswerId="9553" CreationDate="2014-11-06T23:24:47.083" Score="11" ViewCount="2898" Body="&lt;p&gt;Does the lift of that section of the wing which is in the wake of the propeller increase (because the airspeed in that section is higher)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, is this fact used actively to improve the lift capability?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or does it decrease significantly because of turbulence and an overall disturbed airflow on the wing surface?&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="19" LastEditDate="2015-02-23T15:56:09.660" LastActivityDate="2017-06-08T10:06:44.130" Title="How is lift provided by a wing affected by propeller wake?" Tags="&lt;wing&gt;&lt;turboprop&gt;&lt;lift&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9544" PostTypeId="1" AcceptedAnswerId="9545" CreationDate="2014-11-07T02:26:45.517" Score="15" ViewCount="28014" Body="&lt;p&gt;Why would someone prefer to own a single-engine vs. a twin-engine airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the pros and cons of each?&lt;/p&gt;&#xA;" OwnerUserId="3994" LastEditorUserId="21091" LastEditDate="2017-09-15T05:20:23.660" LastActivityDate="2017-09-15T05:41:31.440" Title="What are the pros and cons of single-engine vs. twin-engine?" Tags="&lt;aircraft-design&gt;&lt;single-engine&gt;&lt;aircraft-purchase&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9545" PostTypeId="2" ParentId="9544" CreationDate="2014-11-07T02:53:50.160" Score="14" Body="&lt;p&gt;In the light aircraft world there are a few trade-offs to consider.  The short version:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Single-Engine Pros:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Simplicity&lt;br&gt;&#xA;One engine means fewer controls, a simpler fuel system, simpler vacuum system, simpler electrical system, etc.&lt;/li&gt;&#xA;&lt;li&gt;Operational cost&lt;br&gt;&#xA;Only one engine to feed, so you spend less on - fuel &amp;amp; oil per flight.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance cost&lt;br&gt;&#xA;Only one engine to maintain - One set of spark plugs &amp;amp; cylinders, One engine to overhaul.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Single-Engine Cons:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No redundancy: You have one engine, if it fails you're a glider.&lt;/li&gt;&#xA;&lt;li&gt;Singles generally tend to have less spacious cabins than twins.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Twin-Engine pros:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Redundancy&lt;br&gt;&#xA;If you lose an engine the other will give you a chance to get to a landing site.&lt;/li&gt;&#xA;&lt;li&gt;Cabin space&lt;br&gt;&#xA;If you step up beyond &quot;twin trainers&quot; you can get a very nice cabin in a piston twin.&lt;/li&gt;&#xA;&lt;li&gt;Equipment&lt;br&gt;&#xA;Again, if you step up beyond the &quot;twin trainers&quot; twin-engine planes tend to be &quot;traveling aircraft&quot;, so they often come with nice features like deice/anti-ice equipment.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Twin-Engine cons:&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Operating costs&lt;br&gt;&#xA;Two engines to feed (fuel &amp;amp; oil costs double).&lt;/li&gt;&#xA;&lt;li&gt;Maintenance costs&lt;br&gt;&#xA;Two engines mean twice the cylinders, twice the spark plugs, etc.&lt;/li&gt;&#xA;&lt;li&gt;Complexity&lt;br&gt;&#xA;The redundancy you can get in a twin comes at a price: Synchronizing the propellers, a more complex fuel system (crossfeed), paralleling alternators, vacuum system failover, etc.&lt;/li&gt;&#xA;&lt;li&gt;Short and Soft field performance can be lacking.&lt;/li&gt;&#xA;&lt;li&gt;Failure of an engine &lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_engine&quot;&gt;can be problematic&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In addition to the operational considerations there are some other practical items to consider: twin-engine aircraft require a multi-engine rating (which means more training time). Twins will also generally be more expensive to purchase/rent (and may be more difficult to rent when away from home), and will likely cost more to insure (particularly for low-time pilots).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-07T02:53:50.160" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9547" PostTypeId="2" ParentId="9543" CreationDate="2014-11-07T10:39:49.607" Score="4" Body="&lt;p&gt;According to &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940025432.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this NASA Document&lt;/a&gt; the lift after the propeller is higher and it is used on purpose to create more lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Page-5&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wing-mounted propulsion systems have significant effects on the wing&#xA;  aerodynamic characteristics, and these effects are more pronounced&#xA;  when the highlift components are deployed. Various aerodynamic&#xA;  components contribute to the rise of these effects. Some of these&#xA;  effects are external to the wing performance and affect the&#xA;  measurement of the aerodynamic characteristics of the combined&#xA;  assembly. Examples of these effects are the propeller thrust, the&#xA;  location of the thrust line, tile size and location of the exhaust&#xA;  nozzle, and the thrust from the exhaust nozzle alone. Another group of&#xA;  effects are pure aerodynamic effects, such as the propeller&#xA;  slipstream and the flow past the nacelle and nacelle attachments.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Page-7&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Results indicate that the lift coefficient of the powered wing could&#xA;  be increased by the propeller slipstream when the rotational speed&#xA;  (disk loading) was increased and high-lift devices were incorporated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is also stated, that the exhaust of the turboprop can also create lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&#xA;An exhaust of a free-turbine &quot;PT6A-67&quot; turboprop of a converted Conair Firecat doesn't generate any lift.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/t6dlT.jpg&quot; alt=&quot;Conair Firecat&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But an exhaust of an Direct-drive &quot;Rolls-Royce RB.53 Dart&quot; turboprop YS-11 which is nearly on the wing, can generate additional lift and acceleration.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/grb4j.jpg&quot; alt=&quot;ys11&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Byy1M.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-11-07T11:37:28.500" LastActivityDate="2014-11-07T11:37:28.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9548" PostTypeId="1" AcceptedAnswerId="9550" CreationDate="2014-11-07T11:50:12.793" Score="62" ViewCount="28226" Body="&lt;p&gt;What were the advantages and why was it never produced?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SZgDm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SZgDm.jpg&quot; alt=&quot;Spinning wing airliner diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="5517" LastEditDate="2015-02-25T20:05:06.803" LastActivityDate="2016-05-25T08:13:31.917" Title="What are the advantages of a Spinning Wing (Magnus Effect) and why haven't any been commercially produced?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9549" PostTypeId="2" ParentId="9475" CreationDate="2014-11-07T13:40:25.310" Score="0" Body="&lt;p&gt;Joe pilot answer was not totaly correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll try to explain in a more easy way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are on ISLND in a Direct heading (273° for 14.5nm) for FHR NDB.&#xA;When you are over FHR NDB, start your left turn to intercept the RAD 159° FROM FHR, and begin descent 2300ft&#xA;At 10nm, you need to turn left heading 114° after 1min or 2min  right turn to HDG 294° and intercept RAD 339° TO FHR, when you are on RAD 339° TO FHR, i wish you a great approach and an Happy Landing ! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think, Dotted line was used for Go Around Procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Sorry if my english is not perfect)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit : A friend gived to me a &lt;em&gt;Jeppesen&lt;/em&gt; Chart of KFHR (maybe outdated, but very close to your chart), but i only display a little part of the chart&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GRY2l.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3808" LastEditorUserId="3808" LastEditDate="2014-11-07T20:26:39.937" LastActivityDate="2014-11-07T20:26:39.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9550" PostTypeId="2" ParentId="9548" CreationDate="2014-11-07T14:04:35.127" Score="70" Body="&lt;p&gt;Some earlier prototypes of spinning-wing aircraft were produced but none were successful. The design has some very serious disadvantages. One of the main issues appears to be undesirable gyroscopic effects.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Production&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;... why it was never produced?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Several full-scale prototype aircraft with rotating Magnus-effect wings seem to have been produced:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flettner_airplane&quot; rel=&quot;noreferrer&quot;&gt;921-V&lt;/a&gt; - Plymouth. 1930.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://1000aircraftphotos.com/Misc/2367.htm&quot; rel=&quot;noreferrer&quot;&gt;X772N&lt;/a&gt; - Union Aircraft Co. 1931.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It may be that 921-V is the only one to have flown, crashing after one flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flettner_airplane&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bWKV0.jpg&quot; alt=&quot;enter image description here&quot;&gt;   &lt;sup&gt;&lt;em&gt;The Flettner airplane&lt;/em&gt;&lt;/sup&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Built in 1930 (USA), the 921-V is reported to have been flown at least once - ending it's short career with a crash landing. Three cylinders with disks performing as winglets driven by a separate engine. Information on this design needed! It's probably the only aircraft equipped with cylinder wings which made it into the air.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;From &lt;a href=&quot;http://www.pilotfriend.com/photo_albums/potty/2.htm&quot; rel=&quot;noreferrer&quot;&gt;Pilotfriend.com&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice the effect can be less efficient than conventional alternatives&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the early 1920's the force from a rotating cylinder was used to power a sailing ship. The idea, proposed by Anton Flettner of Germany, was to replace the mast and cloth sails with a large cylinder rotated by an engine below deck. The idea worked, but the propulsion force generated was less than the motor would have generated if it had been connected to a standard marine propeller! &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;From &lt;a href=&quot;http://www.grc.nasa.gov/WWW/K-12/airplane/cyl.html&quot; rel=&quot;noreferrer&quot;&gt;NASA&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Advantages&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What were the advantages?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://blog.modernmechanix.com/spinning-wing-airliner/&quot; rel=&quot;noreferrer&quot;&gt;article referenced&lt;/a&gt; suggests&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;More wing lift&lt;/strong&gt; and &lt;strong&gt;less drag&lt;/strong&gt; are the major aims of aviation’s researchers. Maybe the Magnus Wing will supply the answers ... The ship is powered by a conventional gas-turbine jet engine, while the drums are revolved by a separate piston engine. &lt;strong&gt;Small wings, heavy loads and quick take-offs&lt;/strong&gt; would be its great advantages.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Disadvantages&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://blogs.yahoo.co.jp/rajisukisuki/folder/500046.html&quot; rel=&quot;noreferrer&quot;&gt;developer of a working model&lt;/a&gt; wrote about a few of the disadvantages (try a google translation of that page for more):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If the cylinder rotation accidentally becomes slow or stops, its lift disappears completely. This plane will never be able to glide. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If a gust blows from backside during a slow flight (takeoff or landing), the cylinder wings generate a down force. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The spinning cylinder wings generate a strong gyro effect, which makes it difficult for the plane to change its attitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.youtube.com/watch?v=acXvl-8xrBM&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt; and comments.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;NASA did some experiments with rotating-cylinders for flaps (not main lift source)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5cvc3.png&quot; alt=&quot;OV-10 with rotating cylinder flaps&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They concluded&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These experiments demonstrated on the one hand the&#xA;  effectiveness of such a high lift system but on the other hand the weakness in handling qualities due to the gyroscopic forces in such an aircraft configuration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;From &lt;a href=&quot;http://www.see.ed.ac.uk/~shs/Climate%20change/Flettner%20ship/Seifert%20Flettner%20apps.pdf&quot; rel=&quot;noreferrer&quot;&gt;A review of the Magnus effect in aeronautics&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The US Army also carried out a study of the use of the Magnus effect in aircraft&#xA;&lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/857462.pdf&quot; rel=&quot;noreferrer&quot;&gt;VIEW AND PRELIMINARY EVALUATION OF LIFTING HORIZONTAL-AXIS ROTATING-WING AERONAUTICAL SYSTEMS&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/P7Dgj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is difficult to pick out a simple conclusion as the study looked at a wide variety of systems. For rotating cylinders in wing (RCIW) they wrote&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Such systems do not appear to have merit as STOL devices.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="718" LastEditDate="2014-11-07T20:21:54.643" LastActivityDate="2014-11-07T20:21:54.643" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9551" PostTypeId="1" AcceptedAnswerId="9554" CreationDate="2014-11-07T14:49:03.690" Score="9" ViewCount="1415" Body="&lt;p&gt;Do helicopters fly the same instrument approaches as fixed-wing aircraft? If so, which approach category and minimums do they use?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-11T16:59:17.617" Title="Do helicopters fly the same instrument approaches as fixed-wing aircraft?" Tags="&lt;instrument-flight-rules&gt;&lt;helicopter&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9552" PostTypeId="2" ParentId="9516" CreationDate="2014-11-07T15:40:16.263" Score="12" Body="&lt;p&gt;I did some searching on this and it's been discussed on some aviation forums (e.g. &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/5156717/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;). I couldn't find any 'official' sources from airlines or regulators but on the other hand there are a lot of comments and observations that seem to make sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple summary would be that it's a result of increased public awareness of airline smoking bans combined with a massive increase in the use of portable electronic devices (PEDs). That has made some airlines decide that it's more important to focus on passenger behaviour with PEDs rather than smoking. &lt;a href=&quot;http://en.wikipedia.org/wiki/Inflight_smoking&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; has an unsupported (citation needed) statement along those lines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Due to the ubiquitous prohibition of in-flight smoking and the&#xA;  increasingly widespread use of electronic devices, the illuminated&#xA;  no-smoking signs have sometimes been re-purposed to inform passengers&#xA;  to switch devices off for take-off and landing. Where this is the&#xA;  case, the no-smoking sign is permanently printed on the overhead&#xA;  panels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Smoking on aircraft has been banned by most (all?) airlines and regulators for some time now (&lt;a href=&quot;http://en.wikipedia.org/wiki/Inflight_smoking&quot; rel=&quot;noreferrer&quot;&gt;since 1988&lt;/a&gt; in the US, for example) and the number of people travelling by air has increased significantly over the same period (e.g. UK foreign travel trend &lt;a href=&quot;http://www.ons.gov.uk/ons/rel/social-trends-rd/social-trends/social-trends-40/social-trends-40---transport-chapter.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;). That means that more and more people know that smoking isn't allowed on aircraft and probably by now that fact has been 'absorbed' at a cultural level, at least in Western countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the last 10+ years the numbers of PEDs in use has &lt;a href=&quot;http://etc-digital.org/digital-trends/mobile-devices/mobile-smartphones/&quot; rel=&quot;noreferrer&quot;&gt;increased massively&lt;/a&gt; and they were banned too. I guess that at some point some airlines decided that the 'rising' issue of PEDs was more important than the 'declining' issue of smoking, and started adapting their signs, briefings etc. accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's interesting that you saw the sign on an Embraer 195, which is used for regional not long-haul flights (as far as I know). Possibly the airline decided that on shorter flights there's less risk of passengers getting desperate for a smoke. But I couldn't find any information on which airlines and aircraft have these signs; that's up to the airline to decide when it orders the aircraft interior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course now the US allows the use of PEDs in all flight phases and that makes it very likely that other regulators will follow. At some point the only sign needed may be the seatbelt one.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-07T15:40:16.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9553" PostTypeId="2" ParentId="9543" CreationDate="2014-11-07T18:30:52.583" Score="9" Body="&lt;p&gt;It both increases and decreases, depending on the local direction of the propellor (e.g. on the upgoing side, or the downgoing side) . See for example this &lt;a href=&quot;http://www.lr.tudelft.nl/fileadmin/Faculteit/LR/Organisatie/Afdelingen_en_Leerstoelen/Afdeling_AEWE/Aerodynamics/Contributor_Area/Secretary/Publications/publications/doc/2005_4_02.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PhD thesis: Propeller Wing Aerodynamic Interference&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This thesis shows the following image:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WDzfi.png&quot; alt=&quot;Prop interaction&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simply said, the velocity of the propellor locally changes the angle of attack, and thus the lift generated by the wing.&#xA;It is interesting to know that it is possible to locally optimize the shape of the wing to take advantage of this effect. Again the thesis shows the result, and it looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1fdAo.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look closely, you can see that the wing is changed at the propellor location to accomodate the adjusted flow.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2017-06-08T10:06:44.130" LastActivityDate="2017-06-08T10:06:44.130" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9554" PostTypeId="2" ParentId="9551" CreationDate="2014-11-07T19:31:35.193" Score="6" Body="&lt;p&gt;Helicopters can fly the same standard IAPS.  The visibility minimum is the greater of&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;a) one half the Category A visibility minima, &#xA;&#xA;b) 1/4 statute mile visibility, or &#xA;&#xA;c) 1200 RVR&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;We use Category A's MDA/DH. See the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim1001.html&quot; rel=&quot;nofollow&quot;&gt;AIM 10-1-2&lt;/a&gt; for more information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also there are Copter IAPs (example &lt;a href=&quot;http://download.aopa.org/ustprocs/current/NE-2/jfk_copter_rnav_gps_028.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;), and the viz/altitude minimums are stated on those plates.&lt;/p&gt;&#xA;" OwnerUserId="390" LastEditorUserId="62" LastEditDate="2014-11-11T16:59:17.617" LastActivityDate="2014-11-11T16:59:17.617" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9555" PostTypeId="2" ParentId="9535" CreationDate="2014-11-07T19:45:47.177" Score="5" Body="&lt;p&gt;Depends on the airport.  When I fly to KBUR I was almost always asked to fly standard patterns and land on runways before taxiing out.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some other airports wants you to go directly on pads, and sometimes has a published procedure to land there like KLGB&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes they ask you to land on a taxiway, and then say &quot;taxi parking,&quot; which means you can do whatever you want from there.  &lt;/p&gt;&#xA;" OwnerUserId="390" LastEditorUserId="3504" LastEditDate="2015-01-04T18:54:18.717" LastActivityDate="2015-01-04T18:54:18.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9556" PostTypeId="1" AcceptedAnswerId="9557" CreationDate="2014-11-07T21:57:34.810" Score="4" ViewCount="2110" Body="&lt;p&gt;I am building a ground effect vehicle and I want to calculate the parasite drag of it.&#xA;So I found &lt;a href=&quot;http://coefficient.http://aero.stanford.edu/stdatm.html&quot; rel=&quot;nofollow&quot;&gt;this site&lt;/a&gt; to calculate the friction &#xA;But I don't know what the &quot;reference length&quot; is. Is it the chord, the wingspan or the mean aerodynamic chord? And in case that the reference length is the chord, is their a different way to measure it for an inverted delta wing?&lt;/p&gt;&#xA;" OwnerUserId="4199" LastEditorUserId="1696" LastEditDate="2015-12-14T19:15:14.223" LastActivityDate="2015-12-14T19:15:14.223" Title="What is the reference length in calculating the friction coefficient?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9557" PostTypeId="2" ParentId="9556" CreationDate="2014-11-07T22:36:16.280" Score="8" Body="&lt;p&gt;Since the site computes atmospheric conditions, only the friction coefficient $c_f$ needs a reference length. This is the length of the object causing friction, measured along the direction of airflow. In case of a wing, it is its local chord, in case of a fuselage, it's the fuselage's length. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each part of an airplane and each section of the wing will have a slightly different $c_f$, depending on local chord length. The highest contribution to friction drag is caused at the leading edge, when the boundary layer is thin and the speed gradient at the surface is steep. The farther downstream you look, the less each additional unit of length will add to friction drag, so the average over the full length (that is what $c_f$ stands for) will become smaller for longer bodies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To compute total drag, you need to add the contribution of each part, multiplied with its surface area relative to the airplane's total area. Yes, for a wing the upper and the lower wetted surface area will each contribute their own drag component. Since airflow is faster on the upper surface of a lift-creating wing, you would need a correction factor to account for the speed difference between upper and lower side, but if the difference is small, you can just assume the same speed everywhere. To be precise: $c_f$ is the friction coefficient of a flat plate parallel to the airstream.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-08T10:07:39.227" LastActivityDate="2014-11-08T10:07:39.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9558" PostTypeId="2" ParentId="9475" CreationDate="2014-11-08T06:45:19.717" Score="7" Body="&lt;p&gt;First of all, do not let the depicted holding pattern confuse you.  It is only there because the missed approach procedure happens to have the hold at the same place, and for the purposes of the course reversal may be ignored.&lt;/p&gt;&#xA;&lt;p&gt;In this case, you have options because the course reversal is simply a &amp;quot;barbed arrow&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0504.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-4-9. Procedure Turn and Hold-in-lieu of Procedure Turn(a)(1)&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;On U.S. Government charts, a barbed arrow indicates the maneuvering&#xA;side of the outbound course on which the procedure turn is made.&#xA;&lt;strong&gt;Headings are provided for course reversal using the 45 degree type&#xA;procedure turn. However, the point at which the turn may be commenced&#xA;and the type and rate of turn is left to the discretion of the pilot&#xA;(limited by the charted remain within xx NM distance). Some of the&#xA;options are the 45 degree procedure turn, the racetrack pattern, the&#xA;teardrop procedure turn, or the 80 degree 260 degree course&#xA;reversal. Racetrack entries should be conducted on the maneuvering&#xA;side where the majority of protected airspace resides. If an entry&#xA;places the pilot on the non-maneuvering side of the PT, correction to&#xA;intercept the outbound course ensures remaining within protected&#xA;airspace.&lt;/strong&gt; Some procedure turns are specified by procedural track.&#xA;These turns must be flown exactly as depicted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In other words, do what you want as long as you either stay on the protected side or correct to intercept the outbound course if you find yourself on the non-maneuvering side and you stay within 10 miles of the NDB.&lt;/p&gt;&#xA;&lt;p&gt;Personally, I would:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cross the NDB and then simultaneously:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Turn left to a heading of about 129 degrees (depending on the wind)&lt;/li&gt;&#xA;&lt;li&gt;Descend to 2,300 feet&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;Start the outbound timing as I cross the 69 degree bearing TO the NDB (90 degrees)&lt;/li&gt;&#xA;&lt;li&gt;Intercept the outbound course of the procedure turn and then fly the rest of the course reversal as depicted (the 45 degree procedure turn).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;However, as I said in the beginning, you can do it however you like within the constraints that the AIM gives.&lt;/p&gt;&#xA;&lt;p&gt;I did find a rather interesting article which states that ICAO rules are a little different, but I won't go into the specifics since this is an FAA chart.  For those who are curious though, take a look at it here:  &lt;a href=&quot;http://code7700.com/course_reversals.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Course Reversals&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="524" LastEditDate="2020-12-12T23:27:55.740" LastActivityDate="2020-12-12T23:27:55.740" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="9559" PostTypeId="1" AcceptedAnswerId="9560" CreationDate="2014-11-08T12:04:54.400" Score="3" ViewCount="6394" Body="&lt;p&gt;I found &lt;a href=&quot;http://adg.stanford.edu/aa241/drag/parasitedrag.html&quot; rel=&quot;nofollow&quot;&gt;this site&lt;/a&gt; with formulas to calculate for the parasite drag. But I wondered if these formulas are to calculate parasite drag or the parasite drag coefficient? So do you have to multiply the calculated value with the square of the velocity, as in the formula for the general drag force?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also wonder if there is a difference between the wetted area of an airfoil and the normal planform area?&lt;/p&gt;&#xA;" OwnerUserId="4199" LastEditorUserId="65" LastEditDate="2014-12-21T13:35:24.763" LastActivityDate="2014-12-21T13:35:24.763" Title="What is the true formula for parasite drag?" Tags="&lt;aerodynamics&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9560" PostTypeId="2" ParentId="9559" CreationDate="2014-11-08T21:24:30.133" Score="4" Body="&lt;p&gt;The philosophy employed on the Stanford site is to convert the product of drag coefficient and corresponding surface area to a &quot;drag area&quot;, which is technically the area of a body with a drag coefficient of 1. See page 1-8 in &lt;a href=&quot;http://dl.kashti.ir/ENBOOKS/NEW/FDD.pdf&quot; rel=&quot;nofollow&quot;&gt;Sighard Hoerner's book &quot;Fluid Dynamic Drag&quot;&lt;/a&gt; for the definition and tons of helpful real-world data on drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To convert this into a drag force, it still needs to be multiplied with the dynamic pressure, which is the product of the square of the velocity, the air density and the factor 0.5. No further inclusion of the surface area is needed, as this is already factored into the drag area values of each drag component.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the drag coefficient lets you compare the relative dragginess of drag components (friction drag, pressure drag, ...). If you want to compare the dragginess of aircraft components (wing, fuselage, tail surfaces, ...), using their drag area adds a factor for their size, making it easier to compare the relative influence of the drag of different aircraft components on total drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your second question: Planform area is the wing area you see in the top view of an aircraft, and the wetted area is the actual area which is exposed to airflow. If you start with the planform area, you need first to subtract the part of the wing which is inside the fuselage. Next, you double the result to account for both sides, top and bottom, and then you divide this sum by the cosine of the dihedral angle and the cosine of the incidence angle to arrive at your wetted area.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-08T21:30:00.923" LastActivityDate="2014-11-08T21:30:00.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9561" PostTypeId="1" CreationDate="2014-11-08T22:39:20.713" Score="4" ViewCount="369" Body="&lt;p&gt;Why are the CJ2+ anti-ice and de-ice systems separately controlled? Wouldn't it be easier for both systems to be controlled with one button/switch (minimize chance of error from occurring)? Are there any aircraft that have the two systems controlled by one button/switch that would be activated as soon as ice is detected?&lt;/p&gt;&#xA;" OwnerUserId="4203" LastEditorUserId="247" LastEditDate="2014-11-09T20:56:47.153" LastActivityDate="2014-11-10T22:21:44.670" Title="Why are CJ2+ Anti-Ice &amp; De-Ice Systems separately controlled?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;anti-ice&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9562" PostTypeId="2" ParentId="9561" CreationDate="2014-11-08T23:19:26.093" Score="1" Body="&lt;p&gt;think of it from an MEL (Minimum Equipment List, manufacturer/governing body approved manual for working equipment &amp;amp; non-working equipment installed on aircraft) stand point if you have 1 switch controlling both systems and the fault lies within the switch, and you don't have a spare (or mx personnel) at the outstation with known-icing conditions probably means you aren't taking off. Yet if you separate systems you might be able to get airborne and play dodge cloud then, remaining clear of known icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for specifics to that aircraft I am not privy as I don't fly it.  Other aircraft that are controlled by logic and automated are pretty self explanatory if you understand the nature of its function.&lt;/p&gt;&#xA;" OwnerUserId="4204" LastActivityDate="2014-11-08T23:19:26.093" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9563" PostTypeId="1" AcceptedAnswerId="9588" CreationDate="2014-11-09T00:22:21.220" Score="9" ViewCount="1947" Body="&lt;p&gt;I recently learned that there is a locking mechanism on the nose wheel of a Robin DR-400. This mechanism locks the nose wheel in place when there is no weight on the wheel. &#xA;In particular, the wheel will be locked when the plane is in the air. And at landing, when there is weight on the wheel again, it unlocks. &#xA;But the nose wheel can also become locked if the center of gravity of the plane is too far back, or may fail to unlock upon landing. In this case, the aircraft becomes uncontrollable, and this can cause a runway excursion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I am wondering a few things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does this mechanism work?&lt;/li&gt;&#xA;&lt;li&gt;What is gained by having the nose wheel lock itself? Rather than for instance a spring-like mechanism that just keep the wheel aligned with the plane when the plane is in the air.&lt;/li&gt;&#xA;&lt;li&gt;Are there other planes with a similar locking mechanism?&lt;/li&gt;&#xA;&lt;li&gt;Are there planes with a different mechanism to keep the nose wheel from moving in flight?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here is what the landing gear looks like. It is not retractable and there are fairings on the wheels for better aerodynamics:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/T0ITd.jpg&quot; alt=&quot;Here is a picture I found with a good view of the landing gear:&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="572" LastEditDate="2015-02-25T07:39:27.283" LastActivityDate="2015-02-25T07:39:27.283" Title="How does the nose wheel lock on the Robin DR400 work?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9564" PostTypeId="1" AcceptedAnswerId="9567" CreationDate="2014-11-09T02:06:35.780" Score="19" ViewCount="36217" Body="&lt;p&gt;On smaller aircraft, like some &lt;a href=&quot;http://cirrusaircraft.com/caps/&quot;&gt;Cirruses&lt;/a&gt; for example, they have parachutes attached to the body of the aircraft that can help the plane &lt;a href=&quot;http://www.theatlantic.com/technology/archive/2014/05/heres-how-a-small-plane-looks-when-it-descends-via-parachute-instead-of-crashing/362105/&quot;&gt;get to the ground safely&lt;/a&gt; in an emergency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering why commercial aircraft (like, say, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737&quot;&gt;Boeing 737&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot;&gt;Airbus A320&lt;/a&gt;) don't do this?  I figure it might have to do with the speed a jet moves at, or maybe the altitude, but I was hoping to get a more complete answer by posting the question here...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="62" LastEditDate="2015-05-07T16:30:42.457" LastActivityDate="2018-06-12T17:05:44.530" Title="Why don't big commercial planes have full aircraft parachutes?" Tags="&lt;safety&gt;&lt;jet&gt;&lt;airframe-parachute&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9567" PostTypeId="2" ParentId="9564" CreationDate="2014-11-09T11:32:22.237" Score="41" Body="&lt;p&gt;The reason for not using full aircraft parachutes can be stitched together by looking at the many related questions. Let me do this for you:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Parachutes will only help when something essential fails at &lt;a href=&quot;https://aviation.stackexchange.com/questions/2186/why-are-commercial-flights-not-equipped-with-parachutes?rq=1&quot;&gt;sufficient altitude for parachute deployment&lt;/a&gt;. As paul said &lt;a href=&quot;https://aviation.stackexchange.com/questions/9243/why-dont-commercial-jet-aircraft-have-a-break-apart-parachute-escape-system&quot;&gt;here&lt;/a&gt;, most accidents happen at take-off and landing where a parachute cannot be successfully deployed.&lt;/li&gt;&#xA;&lt;li&gt;Parachutes big enough to slow down a whole airliner will be very heavy, reducing payload and increasing the number of flights to transport the same number of passengers. The biggest parachutes designed so far were for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster&quot; rel=&quot;noreferrer&quot;&gt;solid rocket boosters of the Shuttle&lt;/a&gt;, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/9243/why-dont-commercial-jet-aircraft-have-a-break-apart-parachute-escape-system&quot;&gt;paul&lt;/a&gt; gave their mass a 3 x 990 kg plus 550 kg for the drogue chute. Wikipedia gives the mass of one SRB at 91,000 kg. Scale this for the zero-fuel mass of an &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family#A320&quot; rel=&quot;noreferrer&quot;&gt;A-320&lt;/a&gt; of 62,500 kg, and the mass will be approx. 2,500 kg. That is equivalent to 25 passengers, or 16% of the A-320's capacity. Adding the parachute will translate into 16% more flights, just to compensate for parachute mass. This is most likely underestimating the true impact because I did not add the mass for structural reinforcements.&lt;/li&gt;&#xA;&lt;li&gt;The opening shock at travel speed would destroy both airplane and chutes. If we want the parachute system to work in as many cases as possible, we need to make deployment possible at up to Mach 0.85, and then the maximum g-load on aircraft and passengers must not exceed 6 g. (See &lt;a href=&quot;http://www.aero.polimi.it/~anghi/bacheca_sp/materiale_didattico/ACSDG_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; for &lt;a href=&quot;https://aviation.stackexchange.com/questions/6411/aircraft-with-the-pilot-in-a-prone-position-and-g-force-effects/6418#6418&quot;&gt;Eiband diagrams&lt;/a&gt; which give time- and direction-dependent limits for the maximum deceleration a human being can survive). This is possible with staggered deployment of several chutes with increasing size, and by sewing parts of the canopy and the parachute's strings together, so they can rip apart during opening, which slows the unfolding process. But I expect that this will add to the mass of the parachute system. It will certainly add to the mass of the aircraft's structure, which is currently limited to &lt;a href=&quot;http://www.satavirtual.org/fleet/A320LIMITATIONS.PDF&quot; rel=&quot;noreferrer&quot;&gt;+2.5 / -1.0&lt;/a&gt; g.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;By looking at point 2 above alone, it becomes clear that the addition of parachutes will most likely drive up air travel casualties. If we need 16% more flights to make the cruise part less dangerous, and still &lt;a href=&quot;https://aviation.stackexchange.com/questions/8447/airline-safety-what-happened-between-1959-and-1962/8452#8452&quot;&gt;most accidents happen during take-off and landing&lt;/a&gt; (which are now 16% more numerous), we gain little. Crashes now involve fewer passengers, but their number goes up. Tickets will become 20% more expensive at least (more if the parachute system costs something, which is very likely), and we all know how the majority of passengers votes when faced with a choice of dearer, somewhat safer flights and 20% cheaper flights at almost the same accident risk.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-12T17:05:44.530" LastActivityDate="2018-06-12T17:05:44.530" CommentCount="19" ContentLicense="CC BY-SA 4.0" />
  <row Id="9568" PostTypeId="1" CreationDate="2014-11-09T13:35:53.073" Score="3" ViewCount="1007" Body="&lt;p&gt;I'm building a ground effect vehicle, but I'm failing to stabilize the lift-off. At a certain speed, the lift force is equal to the weight force, so the vehicle lifts off. But this implements a change in angle of attack, so also an uncontrolled change in lift, as can be seen in &lt;a href=&quot;https://www.youtube.com/watch?v=3NH17sDlDAI&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that I can solve this with an elevator that can oppose the change in angle of attack. Now I'm searching for an equation to calculate the elevator angle to get a stabile and controllable lift off.&lt;/p&gt;&#xA;" OwnerUserId="4199" LastEditorUserId="1696" LastEditDate="2015-12-14T22:24:29.653" LastActivityDate="2015-12-14T22:24:29.653" Title="Is there a formula to compute the elevator angle to stabilize takeoff?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9569" PostTypeId="2" ParentId="9568" CreationDate="2014-11-09T18:13:44.833" Score="6" Body="&lt;p&gt;You need more than the correct elevator incidence. Natural longitudinal stability works by distributing lift over the flow direction such that forward surfaces create proportionally more lift than rear surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it is important to know that only pure supersonic lift will be evenly distributed over the chord length of a wing. In subsonic flow the center of lift is at 25% (and even less for wings of small aspect ratio), so you now need to place the center of gravity such that it will be ahead of the 25% chord line of the sum of all lifting surfaces. To distribute lift for this forward center of gravity location, the incidence of the elevator needs to be several degrees smaller that that of the wing. Adjust incidences (say 5° for the wing and 0° for the tail), and then trim the center of gravity by adding ballast or shifting masses to make the aircraft fly straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since airfoil camber shifts the incidence of zero lift to more negative values, you can alternatively use a cambered airfoil for the wing (say, at now 2°) and use a symmetric airfoil for the elevator at again 0° incidence.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-11-09T18:13:44.833" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9570" PostTypeId="1" AcceptedAnswerId="9571" CreationDate="2014-11-09T23:01:44.423" Score="20" ViewCount="7352" Body="&lt;p&gt;I've been on my fair share of commercial helo rides, primarily in Canada.  Over the course of more than ten rides in three different kind of helos (Bell 407, 412, and I think one other) there was only one time when the pilot wasn't wearing a helmet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth noting that these flights were taking off and landing in very remote areas of the Selkirk mountains, usually on glaciers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, I have been around (US) flight schools since I was 15 years old, and I've never seen an instructor or student helo pilot (flying R22s and similar) wear a helmet.  Also, fixed wing pilots don't wear helmets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do commercial helicopter pilots wear helmets, when instructors and students don't?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a little hard to see, but here's a photo of one of the choppers, and you can see that the pilot is wearing a helmet. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/AMiS7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="97" LastEditDate="2014-11-09T23:10:18.627" LastActivityDate="2019-01-04T12:46:59.953" Title="Why do commercial helo pilots wear helmets?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;helicopter&gt;&lt;pilots&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9571" PostTypeId="2" ParentId="9570" CreationDate="2014-11-10T09:17:53.670" Score="13" Body="&lt;p&gt;The same reason as anyone would wear a helmet - to protect their cranium in circumstances when there is the possibility of damage to that area of the body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopter operations are often low level, sometimes over dangerous terrain and, unlike fixed wing aircraft, they do not have the option to glide away from an engine failure. Low-level operations may not afford the pilot the altitude required for a successful autorotation landing so there is the possibility that they will be going down hard and fast. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking an example of low-level flight over forestry resulting in a forced landing, this may be survivable, but the pilot will be thrown around quite a bit as the aircraft is buffeted by the trees as it goes down. Some head protection would be important to the survivability of this crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few other reasons I could think of apart from the main one above&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some helicopters operate with doors open, up where the birds fly around. A seagul to the head would not make for a happy flight&lt;/li&gt;&#xA;&lt;li&gt;Noise - helo's can be louder than Fixed wing and the helmets could provide better noise cancelling&lt;/li&gt;&#xA;&lt;li&gt;Specialist helo operations such as S&amp;amp;R use equipment such as night vision, which could be mounted on a helmet&lt;/li&gt;&#xA;&lt;li&gt;Habit - ex-military helicopter pilots could just be in the habit of wearing a helmet, and carry this over to civilian operations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-01-05T09:13:29.037" LastActivityDate="2015-01-05T09:13:29.037" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9572" PostTypeId="1" CreationDate="2014-11-10T11:38:56.747" Score="29" ViewCount="6129" Body="&lt;p&gt;Many fighter planes have the capability to refuel in air. When a plane moves in air, turbulence is generated at its back. To refuel, the fighter plane must come near to the parent plane (which has fuel in it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When fighter plane reaches the back of parent plane, it is actually in the turbulent zone of the parent plane. How does fighter plane manage to fly and precisely adjust its position even in the zone of turbulence?&lt;/p&gt;&#xA;" OwnerUserId="4206" LastEditorUserId="1696" LastEditDate="2018-04-26T19:47:11.600" LastActivityDate="2018-04-26T19:47:11.600" Title="How do aircraft refueling in-air deal with wake turbulence?" Tags="&lt;aerodynamics&gt;&lt;fighter&gt;&lt;jet&gt;&lt;refueling&gt;&lt;wake-turbulence&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9573" PostTypeId="2" ParentId="9563" CreationDate="2014-11-10T13:42:44.073" Score="6" Body="&lt;p&gt;I found &lt;a href=&quot;http://www.bea-fr.org/docspa/2004/f-xs040509/htm/f-xs040509.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this report by the French accident investigation bureau (BEA)&lt;/a&gt; that explains how the mechanism works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/605om.gif&quot; alt=&quot;General mechanism: tige=rod; verrou=lock; moyeu=hub&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a rod attached to the bottom of the damper, and the rod has a protuberance at the top. When there is no weight on the wheel, the top of the rod goes down into a notch that is attached to the mainframe, and locks the wheel. So the wheel can no longer turn around the vertical axis, until the damper is compressed again, and the top of the rod comes out of the notch. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/J0mN7.gif&quot; alt=&quot;Close-up view of the top of the mechanism&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when the plane takes off, the nose-wheel aligns itself with the mainframe, disengages from the rudder pedals and locks itself in that position. Upon landing, the damper is compressed, the wheel unlocks and can be used to control the plane.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-11-10T13:42:44.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9574" PostTypeId="2" ParentId="9572" CreationDate="2014-11-10T14:16:55.280" Score="6" Body="&lt;p&gt;Practice. Lots of practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller planes like fighters usually refuel from a hose trailing behind the wing, far enough from (and below) the main body to avoid the worst turbulence. The tanker is completely passive here - the receiving pilot does everything. If it's too turbulent he just backs off and tries again&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger planes use the flying boom method - they're the ones who have to come in right behind the tanker and hold position while the boom gets slotted into place. These planes are a lot heavier than a single-seat fighter and can handle the turbulence better. That doesn't mean it's easy - there are plenty of near-miss videos on YouTube.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-11-10T14:16:55.280" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9575" PostTypeId="5" CreationDate="2014-11-10T17:06:14.137" Score="0" Body="&lt;p&gt;An airframe parachute is used to lower the entire aircraft to the ground in case of structural failure, loss of control or other emergencies. They are fitted (or can be retrofitted) in &lt;a href=&quot;http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems#Aircraft_supported&quot; rel=&quot;nofollow&quot;&gt;some light aircraft&lt;/a&gt;, notably the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cirrus_Aircraft&quot; rel=&quot;nofollow&quot;&gt;Cirrus Aircraft&lt;/a&gt; line. Weight and deployment issues mean they are not considered practical for larger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several possible reasons for deploying an airframe parachute, including the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An engine failure forces a landing on rough or dangerous terrain&lt;/li&gt;&#xA;&lt;li&gt;Structural failure makes the aircraft uncontrollable&lt;/li&gt;&#xA;&lt;li&gt;The aircraft enters an unrecoverable spin&lt;/li&gt;&#xA;&lt;li&gt;The pilot becomes incapacitated&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An airframe parachute should not be confused with a &lt;a href=&quot;http://en.wikipedia.org/wiki/Drogue_parachute&quot; rel=&quot;nofollow&quot;&gt;drogue parachute&lt;/a&gt;, which is used to slow down an aircraft on the ground after landing.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-10T17:06:14.137" LastActivityDate="2014-11-10T17:06:14.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9576" PostTypeId="4" CreationDate="2014-11-10T17:06:14.137" Score="0" Body="An airframe parachute is a large parachute that can be deployed in an emergency to lower the entire aircraft to the ground safely. They are available for various light aircraft but are not considered practical for larger ones." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-23T20:50:28.340" LastActivityDate="2014-12-23T20:50:28.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9577" PostTypeId="1" CreationDate="2014-11-10T17:38:14.030" Score="16" ViewCount="16509" Body="&lt;p&gt;I play a flight-sim called X Plane. The other day while I was approaching an airport a little too fast and knew I couldn't slow down in time. I decided to use the reverse thrust while I was still in the air and this helped dramatically and I was able to land safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But now I'm curious - Would using reverse thrust in a real-life Boeing 747 have the same effect, would it cause the plane to crash, or go out of control?&lt;/p&gt;&#xA;" OwnerUserId="3289" LastEditorDisplayName="user18035" LastEditDate="2017-11-22T17:10:23.990" LastActivityDate="2017-11-22T17:10:23.990" Title="Is it possible to use reverse thrust while airborne?" Tags="&lt;safety&gt;&lt;approach&gt;&lt;boeing&gt;&lt;thrust-reverser&gt;&lt;boeing-747&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="0" ClosedDate="2014-11-11T08:40:00.057" ContentLicense="CC BY-SA 3.0" />
  <row Id="9578" PostTypeId="1" AcceptedAnswerId="9597" CreationDate="2014-11-10T17:40:35.823" Score="8" ViewCount="1183" Body="&lt;p&gt;&lt;a href=&quot;http://chat.stackexchange.com/transcript/message/18518325#18518325&quot;&gt;In chat&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/users/2/falstro&quot;&gt;falstro&lt;/a&gt; mentioned the &quot;UK IMC rating&quot; and described it as &quot;a lighter version of an instrument rating, allows enroute IFR, but no approaches or departures&quot; (although to be fair he also said that he isn't familiar with the exact definition).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The name &quot;IMC rating&quot; implies that it allows flight in IMC, not just filing IFR in VMC for procedural reasons. But if so, and if approaches are not included, then it seems like it would allow a pilot to fly into IMC with no safe way out again if an emergency required an instrument approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what exactly is a UK IMC rating, what does it not allow that a full instrument rating does, and what is the advantage of having it?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-01-12T20:07:08.550" Title="What exactly is a UK IMC rating?" Tags="&lt;instrument-flight-rules&gt;&lt;pilot-certification&gt;&lt;uk&gt;&lt;caa-uk-regulations&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9579" PostTypeId="2" ParentId="9577" CreationDate="2014-11-10T17:49:51.793" Score="12" Body="&lt;p&gt;It may depend on the aircraft and situation but an unintended deployment on one engine lead to the &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=4&amp;amp;LLID=34&amp;amp;LLTypeID=2&quot;&gt;in-flight break up of a 767&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At approximately 15 minutes into the flight and at approximately 25,000 feet altitude, one flight crew member commented that the reverser had deployed.&#xA;  This comment was immediately followed by evidence of a rapid airplane attitude change and subsequent in-flight break up, leading to airplane wreckage falling into remote jungle terrain approximately 94 nautical miles from Bangkok.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-11-10T17:55:56.673" LastActivityDate="2014-11-10T17:55:56.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9580" PostTypeId="2" ParentId="9577" CreationDate="2014-11-10T18:04:14.807" Score="18" Body="&lt;p&gt;Commercial jets are not designed to use reverse thrust in flight. With engines mounted under the wing, the turbulence can affect the lift over that section of wing. Tail mounted engines could interfere with the tail. This, in addition to the huge increase in drag, is what causes loss of control, as in the incidents that RedGrittyBrick mentions. Speed brakes are designed to provide the needed drag for emergency descents or otherwise slowing down faster. If the pilots find themselves too high/fast for an approach, and deploying spoilers/gear/flaps won't fix it, then they should go around for another approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The loss of control is more of a risk when a thrust reverser deploys only on one engine. Other risks are still there, since those thrust reversers are designed to deploy in landing conditions, not flight conditions. Notable exceptions &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_reversal#In-flight_operation&quot; rel=&quot;noreferrer&quot;&gt;listed on Wikipedia&lt;/a&gt; include the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Siddeley_Trident&quot; rel=&quot;noreferrer&quot;&gt;Hawker Siddeley Trident&lt;/a&gt;, though it also mentions that the capability was not often used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aircraft, such as the C-17, can be different. They tend to make &lt;a href=&quot;http://www.youtube.com/watch?v=lUUU-C-7o98&quot; rel=&quot;noreferrer&quot;&gt;extremely steep descents&lt;/a&gt; more often (called a tactical descent/approach), so thrust reversers can be used &lt;a href=&quot;http://www.youtube.com/watch?v=Gdn0465zE4o&quot; rel=&quot;noreferrer&quot;&gt;in flight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did some testing with the stock 747-400 in X-Plane. Deploying the thrust reverser only changes the force applied by the engine, but doesn't seem to affect the air flow. So the loss of lift is not reflected by the model.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-11-14T17:57:19.950" LastActivityDate="2014-11-14T17:57:19.950" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9581" PostTypeId="2" ParentId="9578" CreationDate="2014-11-10T18:05:53.310" Score="9" Body="&lt;p&gt;This is also know in Europe as an &lt;a href=&quot;http://easa.europa.eu/newsroom-and-events/press-releases/easa-publishes-new-rules-pilots-flying-instrument-meteorological&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Enroute Instrument Rating&lt;/strong&gt;&lt;/a&gt; or &lt;strong&gt;EIR&lt;/strong&gt;, which allows flights under &lt;em&gt;Instrument Flight Rules&lt;/em&gt; in the cruise phase, but not for departure or approach. It is based on EASA FCL 825&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FCL.825 En-route Instrument Rating (EIR)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Privileges and conditions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The privileges of the holder of an en-route instrument rating (EIR) are to&#xA;  conduct flights by day under IFR or in IMC in the en-route phase of flight, with&#xA;  any aeroplane for which a class or type rating is held.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The curriculum to obtain an &lt;em&gt;EIR&lt;/em&gt; is lower than for a full &lt;strong&gt;Instrument Rating&lt;/strong&gt; (IR), especially the number of &lt;a href=&quot;http://www.easa.europa.eu/rulemaking/docs/npa/2011/NPA%202011-16.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;hours for theoretical and practical instructions&lt;/a&gt; have been lowered:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) instrument flight instruction.&#xA;  (i) The instrument flight instruction for a single-engine EIR shall include at&#xA;  least 15 hours of flight time by reference to instruments.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/9597/57&quot;&gt;GdD has pointed out in his answer&lt;/a&gt;, this is not the same as the UK CAA IMC Rating. See his answer for more information on this.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-11-11T14:24:15.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9582" PostTypeId="2" ParentId="9572" CreationDate="2014-11-10T18:33:14.907" Score="46" Body="&lt;p&gt;Ex US Navy pilot here.  I flew the S-3 Viking, which refueled via the probe/drogue method, as opposed to the USAF flying boom method.  I can confirm that the receiving plane is below the wake turbulence of the tanker, maybe by 8&amp;ndash;10&amp;nbsp;feet.  Although, even if you should ride up into the wake, the sensation is perhaps not as violent as you might think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The technique they teach is that you just fly formation.  You do NOT fixate on the basket (this is the 'drogue' part of the apparatus, which resembles a big badminton birdie).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, you must position the tip of your probe about 4&amp;nbsp;feet aft of the basket, stabilize, then smoothly add throttle until contact is made.  You may need to hit the basket at a couple of feet per second relative velocity in order for it to latch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you have to maintain position.  It's just formation flying, really.    The hose apparatus on the tanker measures your position fore and aft &amp;ndash; when you are within limits for fuel transfer, a light goes on.  So, as the receiving pilot, you fly formation and maintain your position fore and aft so that the light stays lit.  When you've taken on your gas, you need to exit straight back.  Too much vertical offset can cause the basket to 'whip' as it disconnects.  You can smash a canopy this way &amp;ndash; I've seen it happen, and it's pretty colorful.  You won't soon  live it down.&lt;/p&gt;&#xA;" OwnerUserId="4209" LastEditorUserId="946" LastEditDate="2014-11-11T14:21:07.467" LastActivityDate="2014-11-11T14:21:07.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9583" PostTypeId="2" ParentId="9572" CreationDate="2014-11-10T19:11:41.813" Score="3" Body="&lt;p&gt;The problem is less turbulence than downwash. Flying behind and below the tanker means that both vertical and horizontal position will change the downwash in a way that makes holding the position difficult. Flying behind a tanker is flying in an unstable equilibrium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both falling back and climbing up will position the receiving aircraft in stronger downwash. If the receiving aircraft moves forward relative to the tanker, it flies into reduced downwash angles which let it accelerate further, because with less downwash less power is required for the same flight speed. The opposite happens when it falls back, now the pilot needs to advance the throttle to keep his position.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-11-10T19:11:41.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9584" PostTypeId="2" ParentId="9561" CreationDate="2014-11-10T19:16:50.970" Score="4" Body="&lt;p&gt;Because they do two different things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote FlightSafety's CJ2 Pilot Training Manual:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Anti-ice protection systems are incorporated into wing, engine&#xA;  components, windshield, pitot-static, and angle-of-attack systems, and&#xA;  pylon ram-air scoops.  &lt;strong&gt;These systems should be activated prior to&#xA;  entering icing conditions.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The tail deice system consists of pneumatic boots on the horizontal&#xA;  stabilizers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, anti-ice is used to prevent ice from forming in the first place on the protected surfaces of the aircraft.  This is done where it would either be &quot;bad&quot; to have it form in the first place (pitot-static, angle-of-attack, etc.), or where it would be &quot;bad&quot; to have the ice come off after it has formed (and then go through an engine, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deice is used to remove ice &lt;strong&gt;after&lt;/strong&gt; it has formed.  In this case it is used on the tail which a) isn't critical if it has a little ice, and b) the ice can be broken off after it has formed and it will just fly off the back of the airplane without damaging anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they serve two different purposes (and protect different parts of the aircraft), there are two different controls/switches.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2014-11-10T22:21:44.670" LastActivityDate="2014-11-10T22:21:44.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9585" PostTypeId="2" ParentId="9577" CreationDate="2014-11-10T19:21:25.047" Score="5" Body="&lt;p&gt;The Pilatus PC-6 (a turboprop) can be put the prop into reverse pitch and descend nearly vertically.  Here's a demo &lt;a href=&quot;https://www.youtube.com/watch?v=PU3RecxHRtk&quot; rel=&quot;noreferrer&quot;&gt;https://www.youtube.com/watch?v=PU3RecxHRtk&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-11-10T19:21:25.047" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9586" PostTypeId="1" CreationDate="2014-11-10T19:22:54.230" Score="7" ViewCount="2752" Body="&lt;p&gt;This is a while ago but it has been bugging me now and then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On September 11 2011 (yes exactly 10 years after 9/11!) I was flying Easyjet 3467 from London Stansted Airport (STN) to Copenhagen (CPH). Scheduled departure was 18:40 local time but the flight was heavily delayed (around 4 hours as I recall) due to another bizarre incident. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, as we were finally sitting in the plane and taxiing, suddenly the pilot announces that he just got info that another airplane had been heading to land just where we were and had only been some 60 seconds away! A lot of passengers seemed to gasp for air and the pilot sounded quite shocked as well. But there was no other explanation added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a database of such events so I could look up more about what happened?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found the flight on &lt;a href=&quot;http://www.flightstats.com/go/FlightStatus/flightStatusByFlight.do?airline=%28U2%29%20easyJet&amp;amp;flightNumber=3467&amp;amp;departureDate=2011-09-11&amp;amp;x=29&amp;amp;y=7&quot;&gt;FlightStats&lt;/a&gt; &lt;em&gt;(sign in required)&lt;/em&gt; but there were no real info.&lt;/p&gt;&#xA;" OwnerUserId="4210" LastEditorUserId="97" LastEditDate="2014-11-11T14:02:17.507" LastActivityDate="2014-12-03T18:26:54.887" Title="Was I nearly involved in an accident?" Tags="&lt;website&gt;&lt;uk&gt;&lt;datasets&gt;&lt;incidents&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9587" PostTypeId="2" ParentId="9586" CreationDate="2014-11-10T20:30:40.173" Score="20" Body="&lt;p&gt;No, you were not nearly involved in an accident. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the flight crew is ready to go, an Airbus A320 takes about 40-50 seconds from the moment take-off clearance is given until lift-off. As soon as the aircraft is off the runway, the next one can land. On some busy airports, 60 seconds between take-off clearance and the next landing is a daily occurrence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 60 seconds, there is a lot that can prevent an accident. For example, ATC could instruct the incoming aircraft to go around should the departing traffic not be ready to take-off. This is quite a normal event which happens every day at busy airports around the world. In such a case, the aircraft ready for take-off would have to wait for the incoming traffic to pass overhead. It sounds like you may have experienced such an event. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=zodQpfe7ecc&quot;&gt;video&lt;/a&gt; of something similar happening in Birmingham.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it is a 'normal' event, there is no central database that tracks these issues. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-11-10T20:30:40.173" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9588" PostTypeId="2" ParentId="9563" CreationDate="2014-11-10T21:02:57.307" Score="7" Body="&lt;p&gt;It looks like the &quot;How do they work?&quot; question has already been addressed pretty well, so I'll answer some of the other parts of the question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is gained by having the nose wheel lock itself?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The nose gear is prevented from turning during flight when the rudder pedals are actuated. If the nose gear turned when the rudder was being used in flight, it would add a lot of form drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The nose gear remains straight until it touches down on landing, which prevents it from landing sideways in a crosswind landing where the rudder is being used to maintain runway alignment. This allows the pilot to continue to use the rudder inputs to maintain the centerline through the landing roll without damaging the tires or having a sudden yaw in the direction that the tire is pointing when the nose wheel touches down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rather than for instance a spring-like mechanism that just keep the wheel aligned with the plane when the plane is in the air.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You mean like a Cessna-style spring linkage, where there is not a hard linkage between the rudder pedals and the nose gear? One advantage of not using the Cessna-style springs is that it's easier to taxi with direct linkages rather than spring linkages. Cessnas have a lag between rudder pedal input and the nose wheel actually turning because of the spring linkages, so you have to give directional inputs ahead of when you actually want to turn. With direct linkages, the nose wheel turns immediately when you push the pedals, which makes taxiing a little easier, especially when you're first learning.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there planes with a different mechanism to keep the nose wheel from moving in flight?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes. See above for Cessnas. Also, in larger aircraft (e.g. passenger jets and similar,) there are no mechanical linkages to the nose wheel at all and the nose wheel is turned (mostly) by a separate control from the rudder. This control is called a tiller and it's moved by hand instead of by foot. It looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4BxiX.jpg&quot; alt=&quot;B737 tiller&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/HtRfH.jpg&quot; alt=&quot;tiller&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2014-11-10T22:56:19.500" LastActivityDate="2014-11-10T22:56:19.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9589" PostTypeId="2" ParentId="9572" CreationDate="2014-11-10T21:30:39.417" Score="26" Body="&lt;p&gt;Former B-52 crewdog here...The receiver aircraft flies below the wake turbulence of the tanker.  In the case of the typical USAF method, using the boom, the receiver aircraft flies into a &quot;contact&quot; position and holds there.  The boom operator (boomer) then &quot;flies&quot; to boom to the correct final position, then extends the nozzle into the refueling receptacle, the receiver aircraft just has to stay in the correct position relative to the tanker.&lt;br&gt;&#xA;Whereas, as with &quot;probe and drogue&quot;, the shuttlecock basket is trailing behind and below the tanker, the receiver pilot flies their aircraft such that the refueling nozzle goes into the basket.  I'm not sure if the tanker has any directional control over where the basket goes other than just extending the hose.&lt;br&gt;&#xA;Although the USAF primarily uses the rigid boom method, there were some number of KC-135R's that had the drogue on the end of the boom, so they could refuel Navy and some NATO aircraft.  I don't know about the KC-10, but I would imagine there a few of them also with this capability.   &lt;/p&gt;&#xA;" OwnerUserId="4212" LastActivityDate="2014-11-10T21:30:39.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9590" PostTypeId="2" ParentId="9577" CreationDate="2014-11-11T07:48:02.063" Score="3" Body="&lt;p&gt;As Skip Miller Mentioned the DC-8 thrust reverse was designed for in-flight operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Skip Miller:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It was years ago, but I was on a DC-8 that had been re-engined with&#xA;  turbofans. On this flight, they used reverse thrust in flight to lose&#xA;  altitude quickly. The Captain came on the intercom first to warn the&#xA;  pax of an unusual noise and vibration before he did it, and then he&#xA;  used the reverse thrust. Yes, it was noticible and a bit noisey in the&#xA;  cabin. I am glad he gave the pax warning. Concerning the pax may be a&#xA;  reason why this is generally not done, even if the plane is capable of&#xA;  this maneuver.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;DC-8 Manual ,American International Airways, page 29&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Descent rates of less than 4000 ft/min are sufficient for all normal&#xA;  Operations. A descent rate of 1 000 ft/min is about maximum that Will&#xA;  allow a precise comfortable Level off. This should be closely monitored&#xA;  when within 2 000 Feet of the ground. Reverse thrust, if necessary,&#xA;  may be used in normal descent at speeds above 1 90K IAS. When this is&#xA;  done it is limited to inboard engines only.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Lauda Air Flight 004 (NG0049) overview:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=4&amp;amp;LLID=34&amp;amp;LLTypeID=2&quot; rel=&quot;nofollow&quot;&gt;  Some thrust reversers were designed for limited use in flight (such&#xA;  as inboard engines on the McDonnell Douglas DC-8)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2014-11-11T07:48:02.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9591" PostTypeId="2" ParentId="9578" CreationDate="2014-11-11T08:00:50.477" Score="0" Body="&lt;p&gt;The advantage of having it is that is enables more pilots, due to the lower barriers to obtaining the rating, to fly IMC, for example &quot;on top&quot;, if caught out by unexpected weather which has been a consistent killer of PPLs, particularly due to CFIT.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also opens more opportunities when weather en-route would otherwise prevent a flight and, can provide a more comfortable flight with higher altitudes and guaranteed separation.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2014-11-11T08:00:50.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9592" PostTypeId="2" ParentId="9586" CreationDate="2014-11-11T09:16:43.653" Score="4" Body="&lt;p&gt;The term you want to look for is &lt;a href=&quot;http://www.aviationpros.com/article/10374517/accidents-vs-incidents&quot; rel=&quot;nofollow&quot;&gt;not &quot;accident&quot;, but &quot;incident&quot;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To figure out whether or not a situation qualifies as an “aircraft accident” we must look to the definitions in Part 830. The NTSB defines an “aircraft accident” to mean “an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and &lt;strong&gt;in which any person suffers death or serious injury, or in which the aircraft receives substantial damage&lt;/strong&gt;.” The first portion of this definition is especially important to note for maintenance and ramp personnel. The initial threshold for classification as an aircraft accident is that the aircraft is being operated “with the intention of flight.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since no injury or damage occurred, the even would be classified as an &quot;incident&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the US, NASA runs the &lt;a href=&quot;http://asrs.arc.nasa.gov&quot; rel=&quot;nofollow&quot;&gt;Aviation Safety Reporting System&lt;/a&gt;, a publicly searchable database of accidents and incidents.  The data are mostly about events in the US, although some international incidents are included as well.  The incident you mentioned doesn't appear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The European equivalent appears to be &lt;a href=&quot;https://ec.europa.eu/jrc/en/scientific-tool/eccairs-european-central-repository-aviation-accident-and-incident-reports&quot; rel=&quot;nofollow&quot;&gt;ECCAIRS&lt;/a&gt;.  Unfortunately, access to that database is &quot;restricted to authorized authorities.&quot;&lt;/p&gt;&#xA;" OwnerUserId="487" LastActivityDate="2014-11-11T09:16:43.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9593" PostTypeId="1" AcceptedAnswerId="9601" CreationDate="2014-11-11T10:11:48.430" Score="10" ViewCount="2755" Body="&lt;p&gt;In 2010 nearly all newspaper reported on the new invention of the company Aviointeriors.&#xA;They created new airplane seats called &quot;SkyRider&quot; which you can &quot;stand&quot; in. This should increase Airlines profitability.&#xA;I'm not a big fan of the SkyRider seats but who can I thank, or why don't we see them in Action?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/EYoUT.jpg&quot; alt=&quot;BeforeAfter&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/Qshre.jpg&quot; alt=&quot;skyrider, real&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2014-11-11T16:05:44.727" Title="Why we don't see the &quot;SkyRider&quot; seats in action?" Tags="&lt;cabin-design&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9594" PostTypeId="1" AcceptedAnswerId="9599" CreationDate="2014-11-11T10:14:04.357" Score="8" ViewCount="3619" Body="&lt;p&gt;In the IL-2 flight simulator, when you turn on &quot;markers&quot; for planes you can see a belligerent side, the aircraft belongs to, at a distance up to 6km (3.75 miles) as well as its type with a tail number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in some books I've read mentions that pilots were able to see an aircraft number, its specific painting/livery etc. of other aircraft they encountered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I wonder: in real life, at what distance can such things can be distinguished by a pilot with good sight (I understand that this depends on the size of an aircraft)?&lt;/p&gt;&#xA;" OwnerUserId="4217" LastEditorUserId="4217" LastEditDate="2014-11-11T14:38:53.367" LastActivityDate="2014-11-14T03:11:57.320" Title="What is the longest distance at which an aircraft can be visually identified?" Tags="&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9596" PostTypeId="2" ParentId="9593" CreationDate="2014-11-11T11:16:11.253" Score="7" Body="&lt;p&gt;There are 2 major problems with skyriders&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;They need to be certified, just designing and showcasing them isn't enough to allow you to actually put them in planes. All that media buzz was to round up investors to get them through the certification process and get ready for mass production.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They are not one size fits all, as your second pic shows; overweight passengers will have trouble using the seats, same with children.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Then there is the &quot;bad press&quot; that got around. They would turn economy class even more into the sardine can than it is now. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-11-11T11:16:11.253" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9597" PostTypeId="2" ParentId="9578" CreationDate="2014-11-11T12:12:56.090" Score="4" Body="&lt;p&gt;Falstro's referring to the european en-route IFR rating, not the UK IMC rating. The UK IMC rating (I have one) is a national rating which allows departures, approaches and flight in instrument meteorological conditions, albeit with higher minimums. It can only be used within the UK, not including the channel islands, which means once you leave UK airspace you are no longer allowed to use it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Training for it is a similar curriculum as any other instrument rating:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;NDB and VOR tracking&lt;/li&gt;&#xA;&lt;li&gt;Partial panel&lt;/li&gt;&#xA;&lt;li&gt;Unusual attitude recovery&lt;/li&gt;&#xA;&lt;li&gt;ILS, VOR, NDB, and Surveillance Radar approaches &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The reason for the UK rating is to give private pilots an attainable instrument rating option as the EASA one is aimed at commercial pilots and has a huge amount of unnecessary material and training requirements. This is supposedly being worked on but given it's the EU I'm not holding my breath. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-11-11T12:12:56.090" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9598" PostTypeId="2" ParentId="9594" CreationDate="2014-11-11T13:26:14.203" Score="4" Body="&lt;p&gt;As you can expect for a question of this nature, it depends. Atmospheric condition are a big factor, in hazy conditions you can't see as far. Background and altitude are other factors. It is easy to lose sight of a plane when there are many buildings behind it.&#xA;If you know where to look, like a small plane that announced itself on final, in good conditions you might actually see them from 8 to 10 miles away. Just scanning for traffic you might see a plane from 5 miles away, but in many cases they are less than a mile away before you notice it. There is a difference between looking and seeing. You can look at something but not see it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as reading the N numbers, I doubt that anyone could read one from more than half a mile away. The numbers are supposed to be 1 foot high, if I remember the regs correctly, so looking at one on the ground can give you an idea of the distance you can read it. Some older planes have very small numbers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shape of a plane helps to identify the type. Some planes like Mooneys have distinguishing features like their vertical stabilizer. &lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2014-11-11T13:26:14.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9599" PostTypeId="2" ParentId="9594" CreationDate="2014-11-11T13:32:56.763" Score="12" Body="&lt;p&gt;The key piece of information here is the &quot;Angular Resolution&quot; of the naked eye.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is called in this way because the key parameter is the perceived angle between two points when looking at them. Let's take 2 points that are distant 1 meter one from the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's then put them at a distance from your eyes, the angle you see between them can be computed as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kmeCx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_angle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$angle\_in\_degrees = 2*atan(\frac{distance\_between\_them}{2*distance\_from\_you})*\frac{180}{\pi} $&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;if they are 10 meters from you, they will appear about 5.7° apart&lt;/li&gt;&#xA;&lt;li&gt;at 100 meters from you, they will appear 0.57° apart&lt;/li&gt;&#xA;&lt;li&gt;1000 meters, 0.057° apart&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that two dots 10 meters apart and 100 meters from you will appear with the same 5.7° of the dots 1 meter apart and 10 meters from you: this is why, if you do not have other references, is nearly impossible to understand the distance from you of an object.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you are interested in reading something, in particular the aircraft number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.astro.umd.edu/~thuard/astr288c/lecture6-notes.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;naked eye&lt;/a&gt; cannot distinguish two points that appear less than 0.0128° apart (bright day, with no haze nor warm air distortion)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what we see above, if the lettering is 1m tall, you could distinguish it at about 4 km. &#xA;To actually read it, though, you will have to pick up the details, that will be much smaller: thik of distinguishing a &quot;O&quot; from a &quot;D&quot;, you will have to notice that the left side is straight (or not), a detail much smaller than the total height of the letter and this will greatly reduce you maximum distance at which you can read.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recognizing the livery instead is quite easier, as full portion of the aircraft will be painted, and in this case you only have to pick up the colours, not details of the shapes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could also distinguish the shape of on aircraft from a larger distance, given the much larger dimension of a full aircraft, but as for the letters, smaller details will not be recognizable until you get close enough, where &quot;enough&quot; depends on time of day, weather conditions and size of what you want to observe.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-11-11T15:59:58.827" LastActivityDate="2014-11-11T15:59:58.827" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9601" PostTypeId="2" ParentId="9593" CreationDate="2014-11-11T16:05:44.727" Score="14" Body="&lt;p&gt;There are a lot of disadvantages, even if the possibility of lowering costs and increasing profits is a huge advantage for the airlines. &lt;a href=&quot;http://blog.wandr.me/2010/09/hands-on-with-the-aviointeriors-skyrider-seat/&quot;&gt;This article&lt;/a&gt; discussed several issues from a passenger perspective:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limited space in general (e.g. to use a laptop)&lt;/li&gt;&#xA;&lt;li&gt;Face too close to the video screen in front of you (if there is one)&lt;/li&gt;&#xA;&lt;li&gt;Doesn't fit tall, large, short or young people well (and I guess that older people might not be strong enough to use it)&lt;/li&gt;&#xA;&lt;li&gt;Very limited space for carry-on luggage (because you lose space both under the seats and in the overhead bins)&lt;/li&gt;&#xA;&lt;li&gt;Passenger resistance to the basic idea&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The author's conclusion was that the seat isn't actually uncomfortable, just cramped, but he was very sceptical that passengers would be willing to use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nytimes.com/2010/09/21/business/21road.html?_r=0&quot;&gt;Another article&lt;/a&gt; added some concerns from the airlines' point of view:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Could make cabin evacuations more difficult (and certification costs in general would be high for a completely new seating concept)&lt;/li&gt;&#xA;&lt;li&gt;Difficult to market successfully&lt;/li&gt;&#xA;&lt;li&gt;The manufacturer intended the seats to be used in a new budget fare class, not to replace current economy class seats (this adds more complexity to everything: aircraft layout and maintenance, marketing, booking systems etc.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both articles (and &lt;a href=&quot;http://whotv.com/2014/07/10/coming-soon-standing-instead-of-sitting-on-planes/&quot;&gt;others&lt;/a&gt;) concluded that there's no fundamental technical or regulatory barrier to introducing them, the main problem would be convincing passengers to accept them. Even Ryanair - which is &lt;a href=&quot;http://en.wikipedia.org/wiki/Ryanair#No-frills&quot;&gt;notorious for cutting costs&lt;/a&gt; wherever possible - rejected them although Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Vertical_seat&quot;&gt;says&lt;/a&gt; that both Ryanair and Airbus have proposed an alternative but very similar concept in the past.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airlines really wanted to introduce this seating arrangement, I would expect them to keep the idea in the news as much as possible and generally work on convincing people that the seats are comfortable and it's a great way for them to get even cheaper tickets. Since they haven't done that (if they have, I haven't noticed) it seems unlikely that the airlines are actively working on them.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-11T16:05:44.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9602" PostTypeId="1" AcceptedAnswerId="9605" CreationDate="2014-11-11T18:08:51.717" Score="39" ViewCount="14323" Body="&lt;p&gt;During a normal flight at cruise speed and altitude, amid the delicious airline meal and the enjoying a latest movie, all of a sudden the seat belt sign turns on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then a few seconds later we enter turbulence, grab a hold of that half-finished soda cup and wait patiently for the bumps to be over while looking out the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;strong&gt;how exactly do the pilots know that the airplane is about to enter in an air pocket which will cause turbulence?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... or does it happen like &lt;a href=&quot;http://www.pprune.org/rotorheads/531241-north-sea-helicopter-incident.html#post8247920&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have already gone through the excellent answers &lt;a href=&quot;https://aviation.stackexchange.com/a/2587/65&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/1893/65&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2018-02-21T14:38:27.173" Title="How do pilots foresee turbulence?" Tags="&lt;weather&gt;&lt;pilot-technique&gt;&lt;turbulence&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9603" PostTypeId="1" AcceptedAnswerId="9612" CreationDate="2014-11-11T18:39:19.587" Score="34" ViewCount="9798" Body="&lt;p&gt;Several years ago, I was flying from the USA to Buenos Aires. That's a very long flight, and it was overnight for us.  When I woke up it was early in the morning and we were over Argentina.  I don't remember exactly what the plane was, but it was a very large jet. 767 or something like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As we got close, the pilot came on the intercom and announced that it was too foggy down below to land, but we still had plenty of fuel reserves left and so he was going to fly in circles for a while and see if the rising sun didn't burn off some of the fog.  After about 15 minutes, he came on again and said that the fog was burning off, and we were about to begin our descent into Buenos Aires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was in a window seat, and I looked outside.  We went into a cloud... and never came out.  Literally the first clue I had that we were &lt;em&gt;anywhere near the ground&lt;/em&gt; is when I felt the wheels hit the runway.  And to this day I've always wondered what in the world was going on in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't care how good the pilot's eyes were; there was zero visibility outside that airplane.  That fog we were in was the metaphorical &quot;pea soup&quot;, and he could not possibly have landed visually.  But we came down safe, exactly where we were supposed to be, which means he must have made some sort of instrument-guided landing.  But if he was capable of making a perfect instrument landing at that runway all along, why was the fog reducing visibility ever a concern in the first place?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone here have enough experience to explain what happened that morning?&lt;/p&gt;&#xA;" OwnerUserId="4221" LastActivityDate="2014-11-12T22:11:46.293" Title="What happened during this foggy landing?" Tags="&lt;landing&gt;&lt;visibility&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9604" PostTypeId="2" ParentId="9602" CreationDate="2014-11-11T19:52:01.707" Score="8" Body="&lt;p&gt;TL;DR clouds and a Doppler radar in the nose registering uneven air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane flies into clouds then there will get some turbulence because at the boundary the air will change, especially in thunderclouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clear air turbulence is more devious as it happen in clear air (like it says in the name), these are detected by instruments on the plane like a Doppler radar that can detect the uneven air ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides those methods, planes ahead of them will be able to report that they experiences turbulence so the pilots behind them can anticipate.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="65" LastEditDate="2018-02-21T14:38:27.173" LastActivityDate="2018-02-21T14:38:27.173" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9605" PostTypeId="2" ParentId="9602" CreationDate="2014-11-11T19:53:19.033" Score="37" Body="&lt;p&gt;There are a few ways that pilots are aware of potentially turbulent areas.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Eyesight&lt;/strong&gt;&#xA;The most obvious way is just by looking outside and observing the sky.  Large billowing clouds, called cumulus clouds, indicated pockets of unstable air (the clouds are rising because the air under them is as well).  If the pilots must fly through these clouds then its a safe bet that there will be some turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weather Radar&lt;/strong&gt;&#xA;Just like using your eyes, except the radar can see further through haze and other clouds.  Typically this is useful for finding embedded thunderstorms, but it can also be useful to find areas of potential turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Communication&lt;/strong&gt;&#xA;Pilots talk.  Both to each other and to air traffic controllers.  En route controllers frequently ask pilots for &quot;PIREPS&quot; (pilot reports), to build an accurate picture of the flight conditions at different altitudes.  Often commercial aircraft will request to change altitudes or deviate around weather/ turbulence, so it is in the best interest of the controller to know ahead of time where the bad flight conditions are, and have a game plan of how to route traffic.  This makes it much easier for the controller to route traffic, rather than getting request after request from individual aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2014-11-11T19:53:19.033" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9606" PostTypeId="2" ParentId="9603" CreationDate="2014-11-11T20:03:31.030" Score="6" Body="&lt;p&gt;Aircraft can be certified to fly coupled approaches all the way to touchdown, and even landing roll out.  CATIII ILS approaches, coupled with auto land, allow the computer to fly the jet all the way to the ground, while the pilot just monitors the systems and makes sure that nothing out of the ordinary is happening.  If the weather is below certain minimums then the pilot is required to use this auto land function, and cannot manually fly the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot either used autoland, if the runway was certified for its use, or they waited until just enough fog burned off that they could legally shoot an ILS.  If the visibility really was as bad as you say though, then the pilot would have had to use autoland.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="946" LastEditDate="2014-11-12T22:11:46.293" LastActivityDate="2014-11-12T22:11:46.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9607" PostTypeId="2" ParentId="9603" CreationDate="2014-11-11T20:12:12.723" Score="16" Body="&lt;p&gt;The system that allows planes to land in low visibility is the Instrument Landing System (ILS). Using ILS, a plane can know its position relative to the runway, either as a reference while manually flying, or to allow the autopilot to fly the approach to the runway, or even land the plane. There are different &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot;&gt;categories of ILS&lt;/a&gt; depending on the aircraft and airport equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each category has its own &quot;minimums,&quot; which are the weather conditions required for the approach to be made. This includes the decision height, which is the height above the runway where they must be able to see the runway, the runway visual range (RVR), or the visibility down the runway, and visibility minimum, which is the general visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, the highest category in use is IIIb, which requires an RVR of 150 feet. Category IIIa requires 700 feet. Category II requires 1200 feet, and has a decision height of 100 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your case, the weather was probably below the minimums for one reason or another. After holding for a while, the weather cleared up enough to allow an ILS landing. Runway lights make it easier to see the runway from the cockpit, so from a passenger's perspective, it can seem like &quot;zero visibility&quot;. &lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-11-11T21:46:36.953" LastActivityDate="2014-11-11T21:46:36.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9608" PostTypeId="1" CreationDate="2014-11-11T21:12:16.933" Score="29" ViewCount="29423" Body="&lt;p&gt;I can't seem to find a definite answer to the question on how to enter a traffic pattern when joining from the opposite end of the pattern. No matter who I ask, I'm getting a different answer every time, and they all seem convinced it's the only way to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'd like to ask a broader audience here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say runway 36 is in use, right traffic and you approach from the west. How do you enter the pattern?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pEzQz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm convinced &quot;B&quot; is the right way (safest at least) but recently I heard an ATC conversation where the pilot was instructed to cross overhead and join downwind. He used method &quot;B&quot; but the controller didn't like that because it took too much time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the correct way? Is there a difference between controlled and uncontrolled airports? What about the procedure when approaching from other angles? And is there a difference between the U.S. and other parts of the world?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On March 13 2018, the FAA released the following Advisory Circular regarding this matter: &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1032988&quot; rel=&quot;noreferrer&quot;&gt;AC-90-66B&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="14957" LastEditDate="2020-05-05T14:02:09.913" LastActivityDate="2020-05-05T14:02:09.913" Title="How to join a traffic pattern when passing overhead?" Tags="&lt;approach&gt;&lt;traffic-pattern&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="9609" PostTypeId="2" ParentId="9603" CreationDate="2014-11-11T21:19:22.573" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;But if he was capable of making a perfect instrument landing at that runway all along, why was the fog reducing visibility ever a concern in the first place?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Any technology, including the &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot;&gt;instrument landing system (ILS)&lt;/a&gt;, can fail. Since life depends on it, there have to be methods in place to detect the failure and abort the approach. The final method for this is that the pilot must see the runway or approach lights when the aircraft descends to certain height above ground, the &quot;decision height&quot;. The approach lights are very bright, so they can be seen significantly further than unlit objects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic ILS installation, CAT I, usually has decision height 200 ft, sometimes more if there is uneven terrain on the approach path. There is corresponding minimum visibility that generally corresponds to distance from start of the approach lights at which the aircraft will descend to the decision height.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More advanced installations have monitoring circuits that verify the transmitters emit correct signal which allow using lower decision height or even no decision height for CAT III. The highest category, CAT IIIc, would theoretically allow zero visibility landing, but that would also require instrument taxi guidance that does not exist. So in practice there is always minimum visibility defined so the pilot can visually check correct braking, turn off and taxi. At Buenos Aires it appears currently the best available approach requires 200 m visibility. Could have been more few years back; I don't know when they last upgraded.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-11-11T21:19:22.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9610" PostTypeId="2" ParentId="9608" CreationDate="2014-11-11T21:29:22.727" Score="3" Body="&lt;p&gt;In the Navy, anytime we make a perpendicular entry to the pattern we turn directly downwind.  I'd have to agree with the controller, its a waste of precious time, especially during busy operations, to wait for someone to make a 360 and slam the pattern.  I can't see any useful safety benefit either, if you didn't see aircraft X as it was moving horizontally across your windscreen, what makes you think you'll see it any better by executing a 360?&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-11T21:48:35.343" LastActivityDate="2014-11-11T21:48:35.343" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9611" PostTypeId="2" ParentId="9608" CreationDate="2014-11-11T22:04:10.023" Score="9" Body="&lt;p&gt;This topic can generate a lot of discussion as you've noted, but I think there are some generally accepted conclusions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest case is joining the pattern at a controlled airport because the procedure in any country is the same: follow ATC's instructions (and ask if they aren't clear!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For unmanned airports the picture is less clear-cut, at least in the US where you can join the pattern however you like as long as it's safe. The FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;strongly recommends&lt;/a&gt; &quot;joining on the 45&quot; which is your option B:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When approaching an airport for landing, the traffic pattern should be&#xA;  entered at a 45° angle to the downwind leg, headed toward a point&#xA;  abeam of the midpoint of the runway to be used for landing. Arriving&#xA;  airplanes should be at the proper traffic pattern altitude before&#xA;  entering the pattern, and should stay clear of the traffic flow until&#xA;  established on the entry leg.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Your option A looks somewhat risky, because to join &lt;em&gt;right&lt;/em&gt; downwind at pattern altitude would mean busting through the &lt;em&gt;left&lt;/em&gt; downwind side of the pattern, and it could also be in use by some traffic.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this joining method isn't an absolute requirement, and the traffic, terrain, local procedures etc. could require a different entry. Some pilots will even take a straight-in approach, especially in larger, faster aircraft and/or when there's little active traffic. (That's one point of possible controversy.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside the US the procedures or regulations may be different. In South Africa I was taught a specific procedure for &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Overhead_join&quot; rel=&quot;nofollow noreferrer&quot;&gt;joining overhead&lt;/a&gt;&quot; at an unmanned field and (from memory) it was required by law. I've heard (and Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfield_traffic_pattern#Procedures_in_the_pattern&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt;) that the UK and some other Commonwealth countries also use it, but I don't have any direct knowledge of that. This is how it works and I was required to demonstrate it during my cross-country flight test:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aA7yD.jpg&quot; alt=&quot;Joining an unmanned airport circuit in South Africa&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You circle overhead the field at 2000agl for as long as it takes you to identify the active runway, wind direction, other traffic etc. Then you descend on the &quot;dead side&quot; - i.e. on the opposite side from traffic in the pattern - and cross the runway at the takeoff end at 1000agl before turning downwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is that the procedure keeps you above pattern altitude for as long as possible to give you better visibility and more options if you need to break away. Descending on the dead side gives you good opportunities to spot other traffic already in the pattern as you descend, and crossing the departure end of the runway puts you well above departing traffic. This probably works best in high-wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I've also heard that military aircraft may use different procedures, at least at military airfields. &lt;a href=&quot;https://aviation.stackexchange.com/users/774/ssumner&quot;&gt;SSumner&lt;/a&gt; mentioned in a comment below that the US Air Force uses either the 45-degree entry recommended by the FAA (&quot;VFR entry&quot;) or a straight-in approach (&quot;initial entry&quot;).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-11-13T15:17:39.143" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9612" PostTypeId="2" ParentId="9603" CreationDate="2014-11-11T22:14:32.863" Score="54" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I don't care how good the pilot's eyes were; there was zero visibility outside that airplane. That fog we were in was the metaphorical &quot;pea soup&quot;, and he could not possibly have landed visually.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What you see from a passenger window has little relationship to what the pilot is looking for and can see out his windshield. The pilot is looking for lead-in lights (there's a lot of them) and a sequence flasher that creates the effect of a ball of light starting at the beginning of the lead-in lights and traveling to the runway. In low visibility the tower will typically turn them up to maximum intensity. These lights are very bright, so much so that after catching sight of them I usually asked for them to be turned down. None of this light system is visible from the passenger cabin of a large aircraft save for the fact that you might notice a glow outside as the airplane passes over them when it's dark.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the pilot came on the intercom and announced that it was too foggy down below to land, but we still had plenty of fuel reserves left and so he was going to fly in circles for a while and see if the rising sun didn't burn off some of the fog.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another thing that the pilot can do if he has the fuel and if the sun is about to set, is to loiter until it gets darker. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Runway_visual_range&quot;&gt;runway visual range (RVR)&lt;/a&gt; will generally increase considerably in the dark.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other things at play as well. In patchy and/or blowing fog, what the RVR reads may not accurately reflect what the visibility is anyplace in the runway environment save where the RVR instrumentation is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Occasionally, local politics can also be a factor. In the 1980s I used to fly into an airport that had as its only air service the commuter airline I was flying for. The local government and chamber of commerce very much wanted to keep that air service. The problem was fog. An unwritten accommodation was reached that took advantage of the rule that once inside the outer marker, you can continue the approach even though the RVR dropped below the minimum required. We knew that if the reported RVR was right at the minimun required when we were cleared for the approach, we might well be told after reporting passing the outer marker that it was a lesser value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In two years of flying for that commuter, I never failed to land on the first approach at that airport and neither did most of the captains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect that in today's hypersensitive regulatory environment, this accommodation might not be possible, and I also don't know if the rule is still in force that permits you to continue an approach once inside the outer marker.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="753" LastEditDate="2014-11-12T16:06:01.253" LastActivityDate="2014-11-12T16:06:01.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9613" PostTypeId="2" ParentId="9608" CreationDate="2014-11-11T23:21:14.597" Score="18" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;What is the correct way?&lt;br /&gt;&#xA;Is there a difference between controlled and uncontrolled airports? What about the procedure when approaching from other angles?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Well I'll address your second quesition first: There is &lt;em&gt;&lt;strong&gt;ABSOLUTELY&lt;/strong&gt;&lt;/em&gt; a difference between controlled and uncontrolled fields. At a controlled field you do what ATC tells you to do (and if there's any ambiguity you ask them to clarify what they want you to do).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;At uncontrolled fields in the USA the standard way to enter the VFR traffic pattern is a 45-degree intercept to the downwind leg. The FAA's pronouncements on the issue can be found in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23093&quot; rel=&quot;noreferrer&quot;&gt;AC 90-66A&lt;/a&gt;.&lt;br /&gt;&#xA;A brief and relevant excerpt:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;a. Prior to entering the traffic pattern at an airport without an operating control tower, &lt;strong&gt;aircraft should avoid the flow of traffic until established on the entry leg&lt;/strong&gt;. For example, wind and landing direction indicators can be checked while at an altitude above the traffic pattern. When the proper traffic pattern direction has been determined, &lt;strong&gt;the pilot should then proceed to a point well clear of the pattern before descending to the pattern altitude&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;b, Arriving aircraft should be at the appropriate traffic pattern altitude before entering the traffic pattern. &lt;strong&gt;Entry to the downwind leg should be at a 45-degree angle abeam the midpoint of the runway&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(Emphasis Added)&lt;/p&gt;&#xA;&lt;p&gt;You will find a rich variety of opinions (a polite way of saying &amp;quot;hidebound arguments&amp;quot;) among pilots on the correctness of various other entries, but the 45-to-downwind is what's &lt;em&gt;expected&lt;/em&gt; by most pilots in the US, and it is generally the safest way to enter the pattern (you will be where everyone else expects you to be, and you will have plenty of time to look at the pattern and figure out how you're going to sequence into it).&lt;/p&gt;&#xA;&lt;p&gt;The 45-degree intercept assumes that you are on the side of the runway where you will be flying your downwind leg. If you are on the opposite side you need to position yourself to maneuver for a 45-degree intercept. I am personally a proponent of the technique illustrated below:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WyGFu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WyGFu.jpg&quot; alt=&quot;Pattern Entry - Teardrop to 45&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cross midfield 500-1000 feet above pattern altitude.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At airports where there are multiple pattern altitudes specified, such as a &amp;quot;jet pattern&amp;quot; above the light aircraft pattern, cross at least 500 feet above the &lt;em&gt;highest&lt;/em&gt; pattern altitude to ensure traffic separation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;Proceed away from the airport and clear of the traffic pattern before descending.&lt;/li&gt;&#xA;&lt;li&gt;Make a descending turn to intercept the 45-degree entry&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ideally time your turn and descent such that you're at pattern altitude when you intercept the 45-degree track. If you expect to need more time to descend plan for a longer entry.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;Enter the traffic pattern on a 45-degree-to-downwind.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Note that this is subtly different from your &amp;quot;Option B&amp;quot; (which has the descending turn leading directly into the downwind) in order to comply with the advisory circular's instruction that you should be &amp;quot;well clear of the pattern before descending&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sub&gt;I cribbed the pattern entry graphic from &lt;a href=&quot;http://alliance-airways.net/flightschool/pattern/pattern.php&quot; rel=&quot;noreferrer&quot;&gt;Alliance Airways&lt;/a&gt;, with some minor modifications, as it was the best illustration of the technique I could find.&lt;/sub&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-11T23:21:14.597" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9614" PostTypeId="1" CreationDate="2014-11-11T23:38:26.197" Score="2" ViewCount="546" Body="&lt;p&gt;What is it like working for a domestic airline in Australia (e.g. Virgin, Regional Express, etc)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously we're all here because we're interested in flying, but as for the practical aspects of being employed in the airline industry I'm trying to get an idea of some of the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What does a typical working day look like and what are the hours?&lt;/li&gt;&#xA;&lt;li&gt;What are airlines like as employers?&lt;/li&gt;&#xA;&lt;li&gt;What is the best thing (or things) about your job?&lt;/li&gt;&#xA;&lt;li&gt;What is the worst thing (or things) about your job?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="2693" LastEditDate="2014-11-12T02:27:52.337" LastActivityDate="2014-11-12T02:27:52.337" Title="What is a typical working day like for an Australian airline pilot?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;&lt;airline-pilot&gt;&lt;australia&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2014-11-13T06:26:34.997" ContentLicense="CC BY-SA 3.0" />
  <row Id="9615" PostTypeId="2" ParentId="9603" CreationDate="2014-11-11T23:42:25.843" Score="16" Body="&lt;p&gt;Other's have explained what ILS is, but if you were wondering what the pilot may have seen, it would be something like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vertical red box on the right side indicates whether the plane is correctly following the proper slope into the runway. If the plane drifts lower, the magenta diamond would go higher and vice versa. The horizontal red box indicates whether the plane is correctly centered on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By keeping both in the middle, it allows the pilot or autopilot to preform safe landings even when visibility is not so good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this example it looks like the plane was landing on a runway with a direction of 155 degrees and about to touchdown with 120 &lt;strike&gt;meters&lt;/strike&gt; feet off the ground. The red boxes themselves are for illustration, so they wouldn't be there in real life. Also this display varies between plane manufacturers but conceptually the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jbaEc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from: &lt;a href=&quot;http://commons.wikimedia.org/wiki/File%3APfd_ILS.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia - Jean Victor Kerecz Arruda&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4224" LastEditorUserId="4224" LastEditDate="2014-11-12T04:00:01.623" LastActivityDate="2014-11-12T04:00:01.623" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9616" PostTypeId="2" ParentId="9608" CreationDate="2014-11-12T03:44:53.850" Score="3" Body="&lt;p&gt;I was instructed at an uncontrolled field in Canada some 15 years ago. For a right-hand circuit as shown, if arriving from what would be the west in your illustration, you cross mid field at pattern altitude and turn right to join the downwind. If arriving from the east, you should join the downwind leg at its upwind end. For a left-hand circuit, everything is reversed. In any case, you are typically making no more than a 90 degree turn to join the downwind and you don't cross it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a controlled airport, you will probably be cleared to join whichever leg is most closely aligned to your arrival heading; you might therefore fly straight in to the crosswind, downwind, base, or final leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfield_traffic_pattern&quot; rel=&quot;nofollow&quot;&gt;Wikipedia article&lt;/a&gt; includes procedures for a number of jurisdictions including the US and Canada (which is as I described above), and makes the point that things are done differently in different jurisdictions.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2014-11-12T03:44:53.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9617" PostTypeId="2" ParentId="9602" CreationDate="2014-11-12T06:52:18.103" Score="4" Body="&lt;p&gt;The most common means in level flight is actually the least technological: pilots ahead of them report the turbulence in that area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are listening to the pilot chatter, and you hear &quot;there is light chop&quot;, you can guess that the seatbelt light is about to come on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is &lt;a href=&quot;https://aviation.stackexchange.com/a/1896/945&quot;&gt;an interesting answer to a related question&lt;/a&gt; illustrating this point - the pilot refers to &quot;ride reports&quot; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_report&quot; rel=&quot;nofollow noreferrer&quot;&gt;PIREPS&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, if weather conditions are bad enough to show up on radar, you don't fly into them at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's true that flying into clouds is another time when they know there will be turbulence, but this is most often on ascent or descent, and seatbelts will be on anyhow.&lt;/p&gt;&#xA;" OwnerUserId="945" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-12-26T19:55:05.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9618" PostTypeId="1" AcceptedAnswerId="9625" CreationDate="2014-11-12T11:05:35.113" Score="11" ViewCount="1953" Body="&lt;p&gt;By design, Mode S surveillance radar equipment uses global 24-bit airframe addresses to keep track of the aircraft it is tracking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these addresses also used by higher levels of the ATC system, such as to fill in call signs, flight plans and so forth automatically when the plane first appears in a controller's domain? Or does that still depend on ATC assigning 12-bit squawk codes that pilots set manually?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the Mode S address appear in a flight plan when filed?&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2020-06-16T15:28:16.053" Title="Does ATC use mode S addresses to identify planes?" Tags="&lt;air-traffic-control&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9620" PostTypeId="2" ParentId="9602" CreationDate="2014-11-12T13:42:45.333" Score="5" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ATpubs/AIM/aim0701.html#aim0701.html.6&quot;&gt;FAA&lt;/a&gt; the official Way is still ask a Flight Service Specialists in preflight briefing who the weather forecasts are and if turbulence can occur.&#xA;But additional in the preflight briefing the Pilots can see like on &lt;a href=&quot;http://www.aviationweather.gov/adds/turbulence/turbnav&quot;&gt;this Site&lt;/a&gt; the turbulences.&#xA;&lt;a href=&quot;https://www.faa.gov/pilots/safety/media/ga_weather_decision_making.pdf&quot;&gt;It is also stated in this FAA Document:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For pilot reports (PIREPs), the&#xA;  ADDS Java tool can zoom in on a&#xA;  specific part of the country and&#xA;  specify the type of hazard reported&#xA;  (icing, turbulence, sky and&#xA;  weather). The tool also allows you&#xA;  to limit data to specified altitudes&#xA;  and time periods. Map overlays&#xA;  including counties, highways,&#xA;  VORs, and Air Route Traffic Control&#xA;  Boundaries are available. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-11-12T13:54:29.703" LastActivityDate="2014-11-12T13:54:29.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9621" PostTypeId="1" AcceptedAnswerId="9623" CreationDate="2014-11-12T15:01:00.813" Score="4" ViewCount="1260" Body="&lt;p&gt;The pilot licensing process in Europe seems to be rather, well, complex... I've heard of &lt;a href=&quot;http://en.wikipedia.org/wiki/Joint_Aviation_Authorities&quot; rel=&quot;nofollow noreferrer&quot;&gt;JAA&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/JAR-FCL_(Pilot_License)&quot; rel=&quot;nofollow noreferrer&quot;&gt;JAR-FCL&lt;/a&gt; and now apparently &lt;a href=&quot;https://aviation.stackexchange.com/questions/183/i-have-a-european-easa-license-what-do-i-need-to-do-to-be-allowed-to-fly-in-th&quot;&gt;EASA licenses&lt;/a&gt;, although EASA's website &lt;a href=&quot;http://easa.europa.eu/the-agency/faqs/flight-standards#category-aircrew-regulation&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt; otherwise:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the Agency is not authorised to issue pilot licences and therefore&#xA;  there will not be any EASA pilot licence in the future&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And on top of that, individual countries can issue &lt;a href=&quot;https://aviation.stackexchange.com/a/9597/62&quot;&gt;their own licenses&lt;/a&gt; (or at least ratings) that may not be valid in other countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is there any such thing as a single European (EASA) pilot's license? What I mean by that is a single license that allows a pilot to operate any European registered aircraft in any European country, e.g a UK pilot flying an F-registered (French) aircraft in Germany?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's some overlap with &lt;a href=&quot;https://aviation.stackexchange.com/questions/1210/what-is-the-difference-between-icao-jaa-faa-easa-and-caa&quot;&gt;this question&lt;/a&gt;, but the answers there don't cover the practical use of a single pilot's license throughout Europe in the way I described.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; to clarify some comments, by &quot;Europe&quot; I mean EASA member states (let's keep it simple); and I'm asking about pilot licensing in general regardless of the type of flying. If there's any difference in &lt;em&gt;where&lt;/em&gt; private/commercial/ATP license holders are allowed to operate in Europe that would be interesting to know.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-12T18:01:59.450" Title="Is there such a a thing as a single European pilot's license?" Tags="&lt;easa-regulations&gt;&lt;pilot-certification&gt;&lt;eu&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9622" PostTypeId="2" ParentId="9621" CreationDate="2014-11-12T15:51:45.097" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2011:311:0001:0193:EN:PDF&quot; rel=&quot;nofollow&quot;&gt;light aircraft pilot's license (LAPL)&lt;/a&gt; allows leisure pilots to fly small aircraft in EU member states and is approved by the EASA. It is currently being implemented in member states, and will progressively replace national licenses. In fact, national licenses will cease to exist in the near future, in Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This license allows its holder to act without remuneration as pilot in command in non-commercial operations on single engine piston aeroplanes-land or TMG with a maximum certificated take-off mass of 2000 kg or less, carrying a maximum of 3 passengers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There also is are variants of this license for helicopter pilots, ballons and for sailplanes (LAPL(H), LAPL(B) and LAPL(S)).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this is still a new regulation, involving several different national authorities, and is not yet fully in place. So if you are thinking of getting a pilot's license, you can choose to get the LAPL rather than your national private pilot's license. However, the deadlines for issuing national licenses and for converting licenses to the European standard keep being pushed back.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-11-12T15:51:45.097" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9623" PostTypeId="2" ParentId="9621" CreationDate="2014-11-12T16:20:02.110" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is there ... a single license that allows a pilot to operate any European registered aircraft in any European country,&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.caa.co.uk/docs/2330/Webrevisedv%20May12_17%20Sept_EASA_quickguide__v2.pdf&quot; rel=&quot;noreferrer&quot;&gt;the UK CAA&lt;/a&gt;&#xA;an EASA Part-FCL licence can be used to fly any EASA aircraft in any EASA member country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have interpreted your &quot;Europe&quot; as &quot;EASA member&quot; in order to avoid ambiguity about Switzerland, Croatia, Kalingrad, etc.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most aircraft in Europe are EASA regardless of state of manufacture or registration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The UK currently grants several levels of licence:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;UK National Private Pilot Licence (NPPL) &lt;/li&gt;&#xA;  &lt;li&gt;UK Private Pilot Licence (PPL) &lt;/li&gt;&#xA;  &lt;li&gt;EASA Part-FCL Light Aircraft Pilot Licence (LAPL) &lt;/li&gt;&#xA;  &lt;li&gt;EASA Part-FCL Private Pilot Licence (PPL) &lt;/li&gt;&#xA;  &lt;li&gt;EASA Part-FCL Commercial Pilot Licence (CPL) &lt;/li&gt;&#xA;  &lt;li&gt;EASA Part-FCL Airline Transport Pilot Licence (ATPL)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-11-12T16:20:02.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9624" PostTypeId="2" ParentId="9618" CreationDate="2014-11-12T17:59:19.827" Score="5" Body="&lt;p&gt;(Self-answer after some additional research).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like the 24-bit addresses are not &lt;em&gt;intended&lt;/em&gt; for such identification. Instead the Mode S protocol contains a way for the ATC radar to direct a transponder (identified by a 24-bit address) to send its &lt;em&gt;call sign&lt;/em&gt; (known as &quot;aircraft identification&quot; in ICAO Annex 10.IV) piggybacked on a normal mode S altitude/squawk reply, coded as up to 8 alphanumeric characters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It stands to reason that this is what higher-level ATC functions are based on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2012/InFO12006.pdf&quot; rel=&quot;noreferrer&quot;&gt;Here is one source&lt;/a&gt; saying this is the case. It also implies that (some) ATC facilities don't normally assign discrete squawk codes to flights with working Mode S transponders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(It's not clear to me why the FAA document says the FLT ID is only 7 characters; the data format defined by Annex 10 has room for 8).&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-11-12T17:59:19.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9625" PostTypeId="2" ParentId="9618" CreationDate="2014-11-12T17:59:46.573" Score="9" Body="&lt;p&gt;The Mode S address is not used for identification of aircraft in the higher levels of the ATC system such as the Flight Data Processing System. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mostly the assigned 12 bit code (also known as Mode A code or squawk code) is used to correlate a radar track to a flight plan. The major exception is that in Europe, when the Mode A code is set to 1000 (octal notation), the Mode-S downlinked Aircraft Identity (ACID) is used for flight plan correlation. This is to free up Mode A codes. Usually planned flights are assigned discrete Mode A codes but using ACID / Flight ID correlation, multiple aircraft on a flight plan in the same area can use Mode A code 1000. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downlinked ACID must be equal to the Flight ID used to file the flight plan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Mode S 24 bit address is only used in low level systems; in the Mode S radar, in multilateration systems, in ADS-B receivers and to some extend in tracking systems. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-11-12T18:05:10.510" LastActivityDate="2014-11-12T18:05:10.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9626" PostTypeId="1" AcceptedAnswerId="9628" CreationDate="2014-11-12T18:27:18.900" Score="12" ViewCount="9645" Body="&lt;p&gt;In &lt;a href=&quot;http://avherald.com/h?article=47917846&quot;&gt;this incident&lt;/a&gt; the cabin crew entered baggage compartment to find and secure a smoking suitcase. But that was in ATR-72 which has the baggage compartments on the main deck behind cockpit and aft of cabin and passage between cockpit and cabin goes through the (larger) forward compartment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this incident it was clearly an advantage to be able to get to the cargo. Would it also be possible in some larger planes? Is there any regulation or guideline explaining why it should or shouldn't be possible?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="62" LastEditDate="2014-11-12T19:11:52.833" LastActivityDate="2017-03-15T16:00:22.377" Title="Is it possible to access the baggage compartment in flight?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9627" PostTypeId="2" ParentId="9602" CreationDate="2014-11-12T19:04:52.530" Score="6" Body="&lt;p&gt;Pireps is how I get most of my info. And you should pass them along on handoffs between controllers.  When I get a handoff I say something like &quot;Denver Center, N12345, level 250, light chop&quot;.  They will respond back with &quot;N12345, Denver Center, it should smooth out in 50 miles or so&quot;. &lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-11-12T19:04:52.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9628" PostTypeId="2" ParentId="9626" CreationDate="2014-11-12T19:26:54.427" Score="12" Body="&lt;p&gt;There are 4 classes of cargo compartments listed in &lt;a href=&quot;//www.gpo.gov/fdsys/pkg/CFR-2002-title14-vol1/xml/CFR-2002-title14-vol1-sec25-857.xml&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 25.857&lt;/a&gt; for transport category airplanes. The main concern with in-flight access is in regards to fire safety.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Class A: Crew will easily discover fire from their station (and therefore be able to suppress it as well)&lt;/li&gt;&#xA;&lt;li&gt;Class B: There is a fire/smoke detection system, and access for crewmember to use a hand fire extinguisher&lt;/li&gt;&#xA;&lt;li&gt;Class C: There is a fire/smoke detection system to alert the crew, and a fire extinguishing/suppressing system installed&lt;/li&gt;&#xA;&lt;li&gt;Class E: For cargo-only aircraft (no passengers): There is a fire/smoke detector, and a way to shut off air flow to the compartment&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So basically, there has to be some way to both detect and address a cargo fire. Class A compartments are those such as in the cockpit where a detection system is not necessary. It sounds like the ATR example would be Class B, since they had a fire indication, and the crew had access to extinguish the fire themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In larger planes with cargo in the lower hold, the compartments are usually Class C, so they have a detection system and a suppression system, and in-flight access is not required. As &lt;a href=&quot;//aviation.stackexchange.com/a/9709/1696&quot;&gt;David Richerby's answer&lt;/a&gt; notes, the compartment may be accessible, but that doesn't mean that crew could effectively locate or fight a fire in those areas. Especially for large cargo holds, a fire suppression system installed througout the hold is much more effective than crew members gaining access at certain locations. This also provides the benefit of isolating the main cabin from the fire extinguishing agents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides fires, there are &lt;a href=&quot;//www.latimes.com/nation/nationnow/la-na-nn-alaska-airlines-cargo-hold-20150413-story.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;even rarer instances&lt;/a&gt; where cargo compartment access could be helpful. But even in that case, it was better for the plane to just come back and land to access the cargo compartment.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="609" LastEditDate="2017-03-15T16:00:22.377" LastActivityDate="2017-03-15T16:00:22.377" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9629" PostTypeId="1" AcceptedAnswerId="9631" CreationDate="2014-11-12T22:18:26.867" Score="2" ViewCount="5142" Body="&lt;p&gt;What is the maximum distance the voice messages sent by the tower on a radio channel can be received by an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="4235" LastActivityDate="2014-11-12T23:51:43.163" Title="What is the range of an air traffic control tower's radio transmission?" Tags="&lt;air-traffic-control&gt;&lt;range&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ClosedDate="2014-11-12T23:08:10.317" ContentLicense="CC BY-SA 3.0" />
  <row Id="9630" PostTypeId="2" ParentId="9629" CreationDate="2014-11-12T22:24:51.830" Score="1" Body="&lt;p&gt;Depends on how the antenna, radios, terrain, etc are configured.  I have experience some places that you needed to be very close &amp;lt; 10 miles.  And some places where you could hear ATIS at 60 miles.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2014-11-12T22:24:51.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9631" PostTypeId="2" ParentId="9629" CreationDate="2014-11-12T22:27:02.263" Score="2" Body="&lt;p&gt;VHF transmissions are limited by line of sight. So, assuming the transmitter is at the tower location, and assuming the aircraft is at cruise altitude (say F300, or 30,000 feet or more), the maximum range is perhaps 200 to 300 km before the curvature of the earth eliminates the line of sight. This also depends on weather conditions and the transmitter power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, VHF coverage may be extended using additional transceiver sites on the same (or different) frequency. This is particularly important in mountainous terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For oceanic flights where there is no place to put additional transceiver sites, HF (shortwave) radio can be used which has a much greater range (thousands of km), especially at night. Some aircraft are also equipped with satellite phones so controllers can simply call them. However, this wouldn't be the &lt;em&gt;tower&lt;/em&gt; controllers talking to the pilots over the ocean, as tower controllers aren't responsible for en route control.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="675" LastEditDate="2014-11-12T23:51:43.163" LastActivityDate="2014-11-12T23:51:43.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9632" PostTypeId="2" ParentId="9183" CreationDate="2014-11-13T10:02:58.693" Score="8" Body="&lt;p&gt;Thanks to DeltaLima for the Answer, I want to add the &lt;a href=&quot;https://www.youtube.com/watch?v=fFzUY6KzXeg&quot;&gt;Fokker 100&lt;/a&gt; to the Planes with &lt;a href=&quot;http://books.google.ch/books?id=8VHi7sWfQJAC&amp;amp;pg=PA133&amp;amp;lpg=PA133&amp;amp;dq=fokker%20100%20no%20flaps%20takeoff&amp;amp;source=bl&amp;amp;ots=qPWdO-nPp1&amp;amp;sig=0lxxlBDcu9yhoRNItEJxqmsJcd0&amp;amp;hl=de&amp;amp;sa=X&amp;amp;ei=635kVILmKIfwaKTxgPgE&amp;amp;ved=0CGIQ6AEwBw#v=onepage&amp;amp;q=fokker%20100%20no%20flaps%20takeoff&amp;amp;f=false&quot;&gt;no-flaps take-off&lt;/a&gt; capabilities. But as said you need a higher take-off speed. also stated in table:&lt;img src=&quot;https://i.stack.imgur.com/mpvQd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2014-11-13T10:02:58.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9633" PostTypeId="1" AcceptedAnswerId="9634" CreationDate="2014-11-13T10:03:07.733" Score="4" ViewCount="5645" Body="&lt;p&gt;I recognise that autoland and ILS can enable landings in zero visibility, which I presuppose in this question (e.g. in &lt;a href=&quot;https://www.youtube.com/watch?v=ZRWlkFKENLA#t=317&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; where touchdown happens around 5:22). Further, suppose that the fog is so thick that runway lights are only visible after touchdown.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Then how would landing be safe or reasonable?&lt;/li&gt;&#xA;&lt;li&gt;Would such landings recklessly over-rely on and over-trust technology?&lt;/li&gt;&#xA;&lt;li&gt;Instead, why not wait for increased visibility or divert to another airport?&lt;/li&gt;&#xA;&lt;li&gt;Or does this sort of landing (video linked above) only occur as the last resort, where the aircraft must land, before depleting fuel?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="128" LastEditorUserId="65" LastEditDate="2015-03-05T20:56:50.127" LastActivityDate="2015-10-07T16:22:58.303" Title="How can landing in zero visibility be safe?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;weather&gt;&lt;visibility&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9634" PostTypeId="2" ParentId="9633" CreationDate="2014-11-13T11:04:12.913" Score="11" Body="&lt;p&gt;Such landing is safe, reasonable and completely standard business.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow&quot;&gt;ILS&lt;/a&gt; transmitter is rather simple, so there is not that much that can go wrong. But to qualify as category III, only which can be used with no decision height, it additionally needs monitoring circuits that check whether the correct signal is being transmitted and shut it down if it transmits incorrect signal. There is a strict limit how fast the monitoring circuit must react and the whole system is regularly tested. The monitoring system is already needed for category II, but with weaker limits for reaction time. Additionally the tower ensures no other aircraft and vehicles move in area around the transmitters where they could affect the signal propagation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the aircraft side for auto-land dual channel autopilot is required. So there are two systems that decode the signal and calculate the control input. If the systems disagree or if the signal fails, alarm is sounded and the pilot flying will initiate a go-around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller on tower sees the aircraft on radar, so can verify that the aircraft is indeed approaching the intended runway. If the signal fails in the very last moment and there is not enough time to go around until wheels touch the ground, the aircraft won't have time to divert from course significantly, so the wheels still touch down on the paved surface. If the lateral signal fails during roll out, there is some risk of runway excursion, but that's what the safety areas are for. Runway excursions (to the sides; overruns are another matter, but they are not significant risk here) rarely result in injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is really the same level of safety as for any other system you rely on like engines or hydraulic flight controls and many other systems in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that since there is no taxi guidance, landing in &lt;em&gt;zero&lt;/em&gt; visibility is not really possible anywhere (except, as raportech97 correctly noted below, in emergency). Some visibility is always needed (50 m should be the lowest, airport and aircraft equipment permitting) that also gives pilots chance to manually control the roll out in case of localizer failure in that phase.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-10-07T16:22:58.303" LastActivityDate="2015-10-07T16:22:58.303" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9637" PostTypeId="2" ParentId="8730" CreationDate="2014-11-13T11:20:12.123" Score="5" Body="&lt;p&gt;Geographic (routes, land-based infrastructure) data:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ourairports.com/data/&quot; rel=&quot;noreferrer&quot;&gt;http://ourairports.com/data/&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://openflights.org/data.html&quot; rel=&quot;noreferrer&quot;&gt;http://openflights.org/data.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Coordination (scheduling, flight numbers) data:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.virtualradarserver.co.uk/FlightRoutes.aspx&quot; rel=&quot;noreferrer&quot;&gt;http://www.virtualradarserver.co.uk/FlightRoutes.aspx&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aircraft (registration) data:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;List of national government registers&lt;/em&gt; - &lt;a href=&quot;http://www.gatwickaviationsociety.org.uk/registers_official.asp&quot; rel=&quot;noreferrer&quot;&gt;http://www.gatwickaviationsociety.org.uk/registers_official.asp&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;ICAO address country prefixes&lt;/em&gt; - &lt;a href=&quot;http://www.kloth.net/radio/icao24alloc.php&quot; rel=&quot;noreferrer&quot;&gt;http://www.kloth.net/radio/icao24alloc.php&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;(old) id and routing data&lt;/em&gt; - &lt;a href=&quot;http://www.libhomeradar.org/download/index.php&quot; rel=&quot;noreferrer&quot;&gt;http://www.libhomeradar.org/download/index.php&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4240" LastActivityDate="2014-11-13T11:20:12.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9639" PostTypeId="1" AcceptedAnswerId="9674" CreationDate="2014-11-13T11:57:37.530" Score="12" ViewCount="13551" Body="&lt;p&gt;This Question came up reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/9626/is-it-possible-to-access-the-baggage-compartment-in-flight#comment18169_9628&quot;&gt;this comment&lt;/a&gt; from  &lt;a href=&quot;https://aviation.stackexchange.com/users/802/tohecz&quot;&gt;tohecz&lt;/a&gt; on this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9626/is-it-possible-to-access-the-baggage-compartment-in-flight&quot;&gt;Is it possible to access the baggage compartment in flight?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No elevator to the cargo deck like in thriller movies? I'm disappointed :( /sarcasm&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to some statements on Internet, there are elevators(lifts) on 747s for persons and carts.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6dTuA.jpg&quot; alt=&quot;747&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does anybody have any evidence or photos of their existence on smaller planes than A380s? &lt;/li&gt;&#xA;&lt;li&gt;How do they work? &lt;/li&gt;&#xA;&lt;li&gt;Do they have an electric-motor department on top (This will take much space)?&lt;/li&gt;&#xA;&lt;li&gt;Where are they going to? Are they going to the personnel sleeping cabin? (On the A380 it makes sense)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UUSvd.jpg&quot; alt=&quot;personnel sleeping cabin&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one from a A380 doesn't seem for persons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/t5Iwt.jpg&quot; alt=&quot;a380&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2020-10-21T05:56:29.737" Title="Which aircraft have elevators (lifts)? How do they work?" Tags="&lt;cabin-design&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9640" PostTypeId="2" ParentId="9602" CreationDate="2014-11-13T12:35:10.607" Score="8" Body="&lt;p&gt;At night time and with a broken radar....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above mentioned methods are good but the ability to plan ahead and perhaps even give you that brief whilst we are on the ground is due to the fact that we always carry the latest Significant Weather (SIGWX) charts that cover our route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's what one looks like (&lt;a href=&quot;http://weather.noaa.gov/pub/fax/PGZE05.PNG&quot; rel=&quot;noreferrer&quot;&gt;view in new tab&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5iIfo.png&quot; alt=&quot;SIGWX chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find a legend for such a chart online but basically the thick bold lines indicate strong upper level winds (also known as jet streams). Crossing one of these at right angles is what brings the most amount of turbulence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second to that, the areas contained within the cloudy bubble like shapes (making it very easy for you to understand here ;) ) are areas in which we can expect to find CB clouds or other storm related activity. Of course, flying through a big lumpy CB cloud will almost always have turbulence associated with it. ISOL EMBD means the CB clouds are isolated (relatively speaking few and far in between) and may also be embedded inside other types of clouds that are in that area. Most of the time and especially in winter we fly above these areas anyway (for cruise at least).&lt;/p&gt;&#xA;" OwnerUserId="4167" LastEditorUserId="65" LastEditDate="2014-11-13T14:28:36.853" LastActivityDate="2014-11-13T14:28:36.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9641" PostTypeId="2" ParentId="8944" CreationDate="2014-11-13T13:27:41.003" Score="1" Body="&lt;p&gt;They did have an engine out failure about a year ago which set everything back a bit.  They've had it at Osh a couple of years now.  Two years ago they were saying around the end of '14 beginning of '15.  Last summer, they were saying months.  If you're really curious, I would talk to the manufacturer in Kansas.  Dealers really aren't part of the FAA approval process...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wouldn't read too much into the range calculator.  I would imagine that they would be adjusting numbers numerous times before release as they get more data.&lt;/p&gt;&#xA;" OwnerUserId="2116" LastActivityDate="2014-11-13T13:27:41.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9642" PostTypeId="1" AcceptedAnswerId="9690" CreationDate="2014-11-13T14:18:28.437" Score="1" ViewCount="325" Body="&lt;p&gt;The separation minima in Europe are in general 5NM lateral or 1000ft vertical. If the safety distance is too small, there is a conflict (loss of separation). When both aircraft are on the same track, the adherance to the minimal separation is relatively easy. But if two trajectories cross the same point horizontally, for example over a beacon, the adherance to the separation minima seems not that easy anymore. The same is true for ascending or descending flights which burst through different flight levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is the adherence to the separation minima for IFR flights enough to avoid airborne conflicts for crossing/ascending/descending flights, too?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, what is the minimum distance between two flights in space and time, that precludes all the different possible &lt;a href=&quot;http://www.mmi-interaktiv.de/uploads/media/spaeth.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;conflict types [page5]&lt;/a&gt;? For example there are &lt;a href=&quot;http://en.wikipedia.org/wiki/Separation_%28aeronautics%29#Local_conflict&quot; rel=&quot;nofollow noreferrer&quot;&gt;local conflicts&lt;/a&gt;, which occur, when two aircrafts cross a given point from different directions in under 4 minutes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This questions refers to the european airspace at best. See the linked question &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight&quot;&gt;How much is the minimum safe distance between two planes in-flight?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3859" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-02-12T10:49:58.377" Title="Is it enough for crossing/ascending/descending IFR-flights to adhere to the separation minima?" Tags="&lt;instrument-flight-rules&gt;&lt;eu&gt;&lt;separation&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9643" PostTypeId="1" CreationDate="2014-11-13T17:09:25.673" Score="3" ViewCount="1043" Body="&lt;p&gt;For example can one get another license in a foreign country?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which countries allow that?&lt;/p&gt;&#xA;" OwnerUserId="4242" LastEditorUserId="65" LastEditDate="2014-12-21T13:38:43.563" LastActivityDate="2016-04-25T19:53:52.333" Title="In which countries a medically unfit US pilot can fly?" Tags="&lt;medical&gt;&lt;international&gt;&lt;regulations&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2014-12-30T03:04:19.847" ContentLicense="CC BY-SA 3.0" />
  <row Id="9644" PostTypeId="2" ParentId="9633" CreationDate="2014-11-13T17:17:17.057" Score="5" Body="&lt;p&gt;A completely blind landing using instrumentation is classified as a category IIIc and requires appropriate equipment both on the ground and on the aircraft. Only a handful of runways around the world support this level of landing because it is expensive and not many aircraft/pilots are rated to perform such landings. Just the lighting arrangements alone are very expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any situation in which you cannot see the full runway is very dangerous because if there is an obstruction you will not be able to see it (and vice versa). Also, how would you taxi? Having lots of aircraft trying to taxi around a low visibility airport is an invitation for an accident, because if the aircraft makes a wrong turn, and the tower cannot see the aircraft (duh) then the aircraft could move onto an active runaway. Meanwhile another aircraft taking off or landing on the runway, likewise would not be able to the obstruction to avoid it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see from this description how a blind airport can quickly turn into a dangerous environment. For this reason, airports usually stop operating when visibility drops below a few hundred yards.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-11-13T17:17:17.057" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9645" PostTypeId="1" AcceptedAnswerId="9650" CreationDate="2014-11-13T17:49:12.027" Score="48" ViewCount="10565" Body="&lt;p&gt;My father used to work as an air traffic controller, and often I heard mention of a 'running rabbit'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, vermin on the runways of airports can be a bad thing, but I don't think he was literally talking about animals.&lt;/p&gt;&#xA;" OwnerUserId="2245" LastActivityDate="2018-10-24T20:46:06.057" Title="What is a running rabbit?" Tags="&lt;airport&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9646" PostTypeId="2" ParentId="9645" CreationDate="2014-11-13T17:49:12.027" Score="10" Body="&lt;p&gt;&quot;Running Rabbit&quot; is a colloquialism.  It refers to the sequenced flashing lights that lead up to the runway threshold, which are part of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Approach_lighting_system&quot;&gt;ALS&lt;/a&gt; (Approach Lighting System).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the wikipedia article linked above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sequenced flashing lights are sometimes colloquially called the rabbit or the running rabbit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2245" LastEditorUserId="2245" LastEditDate="2014-11-13T17:54:19.207" LastActivityDate="2014-11-13T17:54:19.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9647" PostTypeId="5" CreationDate="2014-11-13T18:05:51.217" Score="0" Body="&lt;p&gt;Use this tag for any questions about specific words, phrases or definitions in aviation. If possible, add other tags to indicate the general subject area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a question about terminology used in radio transmissions then you should usually use the &lt;a href=&quot;/questions/tagged/phraseology&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'phraseology'&quot; rel=&quot;tag&quot;&gt;phraseology&lt;/a&gt; or &lt;a href=&quot;/questions/tagged/radio-communications&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'radio-communications'&quot; rel=&quot;tag&quot;&gt;radio-communications&lt;/a&gt; tags instead, but using &lt;a href=&quot;/questions/tagged/terminology&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged 'terminology'&quot; rel=&quot;tag&quot;&gt;terminology&lt;/a&gt; is still fine if you aren't sure.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-13T18:05:51.217" LastActivityDate="2014-11-13T18:05:51.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9648" PostTypeId="4" CreationDate="2014-11-13T18:05:51.217" Score="0" Body="For questions about words, phrases and definitions that are specific to aviation or used in a different way in aviation." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-11-13T18:05:51.217" LastActivityDate="2014-11-13T18:05:51.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9649" PostTypeId="2" ParentId="9645" CreationDate="2014-11-13T19:18:01.937" Score="13" Body="&lt;p&gt;Check out this &lt;a href=&quot;http://youtu.be/FdjeKRNx5Yc?t=16s&quot;&gt;YouTube video&lt;/a&gt;.  Between approximate 0:18 and 0:30, you can see a set of strobe lights leading up to the runway.  They flash in sequence to make a moving dot that runs up the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the &quot;rabbit&quot;.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-11-13T19:18:01.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9650" PostTypeId="2" ParentId="9645" CreationDate="2014-11-13T19:25:20.963" Score="55" Body="&lt;h2&gt;Background&lt;/h2&gt;&#xA;&lt;p&gt;The Sequenced Flashing Lights are part of some &lt;a href=&quot;http://en.wikipedia.org/wiki/Approach_lighting_system&quot; rel=&quot;noreferrer&quot;&gt;approach lighting systems&lt;/a&gt; and are a row of strobe lights that flash in sequence to direct the pilots eyes to the runway.  They are useful in conditions of bad weather, as they quickly catch the eye and help the pilot locate the runway threshold which might otherwise be hidden; however, during normal operations they can actually be distracting.  These lights appear to run towards the runway and are often called chasers, the rabbit, or the running rabbit.&lt;/p&gt;&#xA;&lt;h2&gt;Kill the Wabbit&lt;/h2&gt;&#xA;&lt;p&gt;Because these lights are very bright, and often distracting during normal operations in clear weather, it is not uncommon to hear pilots ask the controllers to &lt;em&gt;kill the w/rabbit&lt;/em&gt; on their approach.  I personally find them overkill, and have heard many other pilots asked them to be turned off as well.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.atgairports.com/pr/images/Approach-R32L.JPG&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kd3xE.jpg&quot; alt=&quot;ALS lights from the ground&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Photo credit &lt;a href=&quot;http://www.atgairports.com/pr/ATG_PR8.htm&quot; rel=&quot;noreferrer&quot;&gt;ATG Airports&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-10-24T20:46:06.057" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="9651" PostTypeId="1" AcceptedAnswerId="9664" CreationDate="2014-11-13T19:51:21.783" Score="5" ViewCount="4222" Body="&lt;p&gt;This question is similar to these questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/847/are-there-any-lsa-aircraft-that-can-be-flown-ifr-in-imc&quot;&gt;Are there any LSA aircraft that can be flown IFR in IMC?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1378/what-are-the-faa-requirements-for-an-aircraft-to-be-ifr-certified&quot;&gt;What are the FAA requirements for an aircraft to be IFR certified?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Unfortunately I couldn't find a definite answer to the following question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a private pilot is instrument-rated, can he/she file an IFR flight plan and fly IFR in IMC in a Cessna 162 (Skycatcher), assuming the C162 is equipped with the optional autopilot? (is it really a requirement to have a functioning autopilot for IFR in IMC?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, the Skycatcher has all the required equipment for IFR, including a &quot;real&quot; Continental engine (unlike most other LSA's using Rotax engines)&lt;/p&gt;&#xA;" OwnerUserId="4" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-12-08T14:39:22.423" Title="Can a Cessna 162 Skycatcher be flown IFR in IMC?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;aircraft-certification&gt;&lt;imc&gt;&lt;cessna-162&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9652" PostTypeId="1" AcceptedAnswerId="9654" CreationDate="2014-11-13T20:11:03.390" Score="19" ViewCount="9139" Body="&lt;p&gt;How much oxygen do commercial airliners carry? Is is enough for every seat to have a 20-30 minute supply, is it a percentage of total flight time (ie 10% of total flight time), or is there a compressor on board?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would assume the goal of the pilots during depressurization would be to repressurize whether that be by simply lowering altitude or other means. Thus, I would assume (hope) there would be sufficient reserves of O2 to do one or the other.&lt;/p&gt;&#xA;" OwnerUserId="3699" LastEditorUserId="3699" LastEditDate="2014-11-14T18:12:09.433" LastActivityDate="2014-11-14T19:20:33.460" Title="How much oxygen do commercial airliners carry?" Tags="&lt;safety&gt;&lt;airlines&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9653" PostTypeId="1" AcceptedAnswerId="9666" CreationDate="2014-11-13T20:15:35.483" Score="25" ViewCount="27265" Body="&lt;p&gt;It seems that only jet engines with afterburners use &lt;a href=&quot;http://en.wikipedia.org/wiki/Propelling_nozzle#Types_of_nozzle&quot;&gt;adjustable area nozzles&lt;/a&gt; (this means adjusting the &lt;a href=&quot;http://youtu.be/x5ccK94IvsA?t=5m47s&quot;&gt;area&lt;/a&gt; of the nozzle but &lt;em&gt;not&lt;/em&gt; necessarily the &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_vectoring&quot;&gt;direction&lt;/a&gt;). This includes most fighter jets, as well as bombers like the B-1B and Tu-160. Outside of the military or afterburning engines, they don't seem to be used, even for smaller engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this? Is the Variable Area Fan Nozzle (VAFN) concept related?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia explains that it is related to supersonic operation; I'm looking for a more detailed explanation about the reasons for this.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-05-04T16:16:10.553" LastActivityDate="2019-04-14T13:57:15.290" Title="Why are adjustable area jet engine nozzles mostly limited to military use?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;" AnswerCount="7" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9654" PostTypeId="2" ParentId="9652" CreationDate="2014-11-13T20:17:33.957" Score="31" Body="&lt;p&gt;The masks are connected to a &lt;a href=&quot;https://i.stack.imgur.com/fRLf3.jpg&quot; rel=&quot;noreferrer&quot;&gt;chemical oxygen generator&lt;/a&gt; by a lanyard.  Pulling the mask pulls the lanyard, which pulls a pin from the generator and starts the reaction.  They typically last betweeen about 10 and 20 minutes, more than enough time to get down to 10,000 feet where additional oxygen is not required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no need for a % of flight time since the crew will descend to a safe altitude then divert to the nearest suitable field.  Therefore, the only requirement is to last during the (emergency) descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot &quot;repressurise&quot; since the cabin altitude will be the same as the external altitude.  The only thing to do is to increase the partial pressure of oxygen by descending.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth mentioning that the flight crew each have their own, isolated supply from a bottle which lasts significantly longer.  This is so that they can continue to fly if there are fumes in the cockpit.  Cabin crew often have their own, smaller, portable bottles so that they can freely move about the cabin to assist the &quot;self loading freight&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many's a morning when I would arrive to work feeling, ahem, a little &quot;under the weather&quot; and nip into the cockpit for a couple of minutes on 100% oxygen.  Works wonders - and don't worry, they are topped up to full as part of the pre-flight service.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="64" LastEditDate="2014-11-13T20:57:09.893" LastActivityDate="2014-11-13T20:57:09.893" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9655" PostTypeId="2" ParentId="9652" CreationDate="2014-11-13T20:19:57.017" Score="7" Body="&lt;p&gt;They don't carry oxygen tanks for each passenger but instead use &lt;a href=&quot;http://en.wikipedia.org/wiki/Chemical_oxygen_generator&quot; rel=&quot;nofollow&quot;&gt;chemical oxygen generators&lt;/a&gt; that activate can provide at least 15 minutes of oxygen. They activate when the person pulls down the mask.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These 15 minutes is enough for an emergency descent to a safe altitude ~10k ft where there's enough oxygen in the air for people to breathe without needing the mask any more.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="946" LastEditDate="2014-11-13T22:54:08.160" LastActivityDate="2014-11-13T22:54:08.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9656" PostTypeId="1" CreationDate="2014-11-13T20:24:26.843" Score="4" ViewCount="438" Body="&lt;p&gt;A few weeks ago I finally finished all of my USPA A license requirements. My instructor signed off the final things and even the card but forgot to put the stamp itself on the form. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was about to send the form off to get my A license card but am hesitant without the stamp. Do I need the stamp to have it processed? More importantly, will I be able to use my paper form as the temporary A license without the stamp? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I normally wouldnt have an issue just going back to see him, but I am overseas for several months and really wanted to jump when I take leave. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm hoping to find an instructor or someone with personal experience with this... Thanks!&lt;/p&gt;&#xA;" OwnerUserId="4243" LastActivityDate="2014-11-14T18:17:19.543" Title="Do I need a stamp for my USPA license?" Tags="&lt;skydiving&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9657" PostTypeId="1" AcceptedAnswerId="9667" CreationDate="2014-11-13T20:27:16.367" Score="4" ViewCount="1707" Body="&lt;p&gt;I just saw &lt;a href=&quot;https://biology.stackexchange.com/questions/16759/can-human-survive-falling-from-30-000ft-without-chute?rq=1&quot;&gt;this question&lt;/a&gt; about humans surviving terminal velocity free-falls, sometimes even with little injury depending on the surface conditions, particularly over forests, hills, or thick snow cover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That made me wonder, if a passenger of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a large commercial aircraft, perhaps a Boeing 737&lt;/li&gt;&#xA;&lt;li&gt;crashing from 5000 meters or higher&lt;/li&gt;&#xA;&lt;li&gt;above a large forest or thick snow&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;had the choice between free falling and buckling up to crash with the aircraft, &lt;strong&gt;which option would offer him the greatest chance of surviving?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking the plane might offer lower falling speed, and physical protection, but also pose the dangers of giant engines, explosions, and crushed metal / shrapnel. Perhaps the answer is that over a forest, the free fall could be safer, and over snow the plane could be safer, but that's pure speculation on my part. &lt;/p&gt;&#xA;" OwnerUserId="4244" LastEditorUserId="-1" LastEditDate="2017-04-13T12:48:15.740" LastActivityDate="2014-11-13T23:49:17.300" Title="In the event of a crash over thick snow or a forest, would it be safer inside the aircraft or free-falling?" Tags="&lt;accidents&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9658" PostTypeId="2" ParentId="9653" CreationDate="2014-11-13T20:27:31.760" Score="1" Body="&lt;p&gt;&lt;s&gt;That adjustable nozzle provides &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;nofollow&quot;&gt;thrust vectoring&lt;/a&gt;. This is most effective at the rear of the plane far from the center of mass, where they provide assistance with pitch and yaw. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So with the under-wing engines it would only help with roll. Pitch and yaw are not helped in that configuration and the existing ailerons are more than enough for that.&lt;/s&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanism is a complex and heavy mechanism that needs maintenance and extra fuel to bring along.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most (all since the concorde) commercial aircraft are subsonic fliers where the change in atmospheric conditions doesn't change the effect of nozzle area enough to warrant the added complexity.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-11-13T20:38:49.947" LastActivityDate="2014-11-13T20:38:49.947" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9659" PostTypeId="2" ParentId="2163" CreationDate="2014-11-13T20:27:35.580" Score="6" Body="&lt;p&gt;There is another procedure which has not been mentioned although I doubt it's ever been used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are lost &lt;strong&gt;and&lt;/strong&gt; the radio has failed &lt;strong&gt;and&lt;/strong&gt; the transponder has failed, flying at least 2 triangles is a recognised distress signal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the transponder has failed, this does require that someone sees you on primary radar which is a long shot.  &lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2014-11-13T20:27:35.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9661" PostTypeId="2" ParentId="9651" CreationDate="2014-11-13T20:30:47.967" Score="0" Body="&lt;p&gt;The 162 is approved for day/night/VFR flight only, though it can serve for IFR training in VFR conditions, it cannot be flown in IMC&lt;/p&gt;&#xA;" OwnerUserId="390" LastActivityDate="2014-11-13T20:30:47.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9662" PostTypeId="2" ParentId="9643" CreationDate="2014-11-13T20:32:39.177" Score="5" Body="&lt;p&gt;It's possible. One example: Bob Hoover &lt;a href=&quot;https://en.wikipedia.org/wiki/Bob_Hoover#End_of_career&quot; rel=&quot;nofollow&quot;&gt;got an Australian license and medical certificate&lt;/a&gt; while his US medical was revoked.&lt;/p&gt;&#xA;" OwnerUserId="520" LastEditorUserId="520" LastEditDate="2016-04-25T19:53:52.333" LastActivityDate="2016-04-25T19:53:52.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9664" PostTypeId="2" ParentId="9651" CreationDate="2014-11-13T20:38:20.453" Score="8" Body="&lt;p&gt;Not in the US. The C162's &lt;a href=&quot;https://support.cessna.com/docs/custsupt/cessnasupport/documents/162PHUS.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;POH&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Model 162 Skycatcher is not equipped or certified for IFR flight&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means that under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_19&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.9&lt;/a&gt; it may not be operated IFR. But, &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8900.1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Order 8900.1&lt;/a&gt; allows an exception for aircraft not certified for IFR to be operated under IFR in VMC only:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;A.    IFR Training in Visual Meteorological Conditions (VMC).&lt;/strong&gt; Instrument flight training may be conducted during VMC in any aircraft&#xA;  that meets the equipment requirements of part 91, §§ 91.109, 91.205,&#xA;  and, for an airplane operated in controlled airspace under the IFR&#xA;  system, §§ 91.411 and 91.413. An aircraft may be operated on an IFR&#xA;  flight plan under IFR in VMC, provided the PIC is properly&#xA;  certificated to operate the aircraft under IFR. However, if the&#xA;  aircraft is not approved for IFR operations under its type&#xA;  certificate, or if the appropriate instruments and equipment are not&#xA;  installed or are not operative, operations in Instrument&#xA;  Meteorological Conditions (IMC) are prohibited. The PIC of such an&#xA;  aircraft must cancel the IFR flight plan in use and avoid flight into&#xA;  IMC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An autopilot isn't required for IFR flight in the US (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1205&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.205(d)&lt;/a&gt;) and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1378/what-are-the-faa-requirements-for-an-aircraft-to-be-ifr-certified&quot;&gt;the question&lt;/a&gt; you linked. I didn't check the full equipment list to see which required instruments are missing from the C162, but even with full IFR equipment if it isn't &lt;em&gt;certified&lt;/em&gt; for IFR then it can't be operated in IMC per the regulations above.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-14T14:26:09.050" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9665" PostTypeId="2" ParentId="9653" CreationDate="2014-11-13T20:41:24.607" Score="2" Body="&lt;p&gt;Seems to me your own link gives the answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Non-afterburning subsonic engines have nozzles of a fixed size because&#xA;  the changes in engine performance with altitude and subsonic flight&#xA;  speeds are acceptable with a fixed nozzle. This is not the case at&#xA;  supersonic speeds as described for the Concorde in section &quot;Nozzle&#xA;  area control during dry operation&quot;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="520" LastActivityDate="2014-11-13T20:41:24.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9666" PostTypeId="2" ParentId="9653" CreationDate="2014-11-13T20:44:45.937" Score="25" Body="&lt;p&gt;A variable area nozzle helps to adjust the exit pressure of the combustion gases to ambient pressure. When they leave the turbine, the combustion gases have still some remaining pressure which is converted into speed by a convergent contour of the nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the combustion gases have enough pressure to be accelerated to supersonic speed, the nozzle is actually first convergent and then divergent to achieve the best acceleration of the flow. The convergent, subsonic flow accelerates until in the section with the smallest area, called the throat, the speed of sound is reached, and the following divergent section accelerates the now supersonic flow further until its pressure drops to ambient pressure. This con-di-nozzle needs to adjust both the cross section of the throat and the cross section of the exit area. Failure to get especially the throat area right will mean substantial thrust loss in operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2ZX3F.png&quot; alt=&quot;con-di nozzle&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Afterburning engines need adaptable nozzles due to the different operating conditions in dry and wet mode, so they profit the most from adjustable nozzles. Reheating the exhaust gas means to increase its volume, so the nozzle needs to become wider to be properly matched. In general, if the exit speed of the combustion gases is supersonic, an adjustable nozzle is required. Even some early jets without afterburners had an adjustable nozzle: The central cone of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_004&quot; rel=&quot;noreferrer&quot;&gt;Jumo-004&lt;/a&gt; nozzle could be moved fore and aft, which changed the location of the bulbous aft section, helping to get the throat area right. Note in the picture below that the cross section widens again in the last part of the nozzle, which shows that the exhaust stream of the Jumo engine was mildly supersonic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GVNW9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliner engines would only gain little from an adjustable nozzle, and considering the mass increase of a fully adjustable nozzle, would in total have lower efficiency. Short-range aircraft usually have nozzle geometries optimized for field performance while long-range aircraft prefer to optimize for best cruise efficiency. Their core flow exit speed is still subsonic or only mildly supersonic - please note that the speed of sound in the heated combustion gas is much higher. At 500°C the speed of sound is almost 560 m/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The variable area fan nozzle tries to do for the fan flow what the regular nozzle does for the core flow of a jet. So this is indeed a related concept and helps to optimize performance both at low and high speed. The picture below is copied from the US patent 2011/0302907A1 and shows an adjustable end part of the cowling (crosshatched, 54). The exit speed of the fan flow is subsonic at take-off and mildly supersonic in cruise, and since its mass flow is much higher than that of the core in airliner engines, making the nozzle variable pays off earlier. By adjusting the exit pressure by varying the exit area it can squeeze out some performance gains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DfuWq.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-04-14T13:57:15.290" LastActivityDate="2019-04-14T13:57:15.290" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="9667" PostTypeId="2" ParentId="9657" CreationDate="2014-11-13T20:53:16.043" Score="8" Body="&lt;p&gt;Statistically, there has got to be graphs you can combine to show the number of airplane crashes to fatalities and a graph with skydives (without a chute/malfunctions) to fatalities. I'd venture to say that the odds are far greater to surviving an airplane crash than a freefall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the factors...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A freefall:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;your velocity in not slowed by anything&lt;/li&gt;&#xA;&lt;li&gt;your body is not protected by anything&lt;/li&gt;&#xA;&lt;li&gt;you have no control on where to 'crash'&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A crash landing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;passengers are slowed greatly by the aircraft&lt;/li&gt;&#xA;&lt;li&gt;passengers are greatly protected physically (airframes are designed to minimize risks from explosions, shrapnel, and crash G's)&lt;/li&gt;&#xA;&lt;li&gt;there is a greater chance the aircraft can be controlled somewhat to crash in the best place.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only time it would be better to jump without a parachute is if you are &lt;a href=&quot;https://www.youtube.com/watch?v=lDBrdl2sZWs&quot;&gt;this guy&lt;/a&gt; or the aircraft is about to be &lt;a href=&quot;https://www.youtube.com/watch?v=Y8Dg6pOEv7Q&quot;&gt;torn apart&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3699" LastActivityDate="2014-11-13T20:53:16.043" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9669" PostTypeId="2" ParentId="9642" CreationDate="2014-11-13T23:04:44.487" Score="3" Body="&lt;p&gt;This might not be the answer to your question, but maybe it will help you understand separation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question specifically asks for how separation is ensured between climbing, descending and crossing traffic over navigational fixes (NAVAIDs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight routes are planned for traffic to use certain flight levels en-route, which follow the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_level#Semicircular.2Fhemispheric_rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;semicircular/hemispherical rule&lt;/a&gt; in effect in that country or are bound to the airway being used. In my example picture below I will use the German semicircular rule of eastbound flights using odd flightlevels. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sYCJM.png&quot; alt=&quot;Two flights crossing over HMM VOR with vertical separation&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: Own Work - Program used: &lt;a href=&quot;http://www.craig-phillips.co.uk/ase/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Situation Editor (ASE)&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both aircraft will cross the HMM VOR roughly at the same time, based on the ground speed displayed. The westbound aircraft (DLH123) is at FL200 (even FL), the eastbound aircraft (BER456) is at FL210 (odd FL). The separation between both aircraft overhead HMM VOR will reduce to 0nm lateral separation, but 1.000ft of vertical separation, and thus, the separation criteria are met.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SfaDe.png&quot; alt=&quot;Two flights crossing over HMM VOR, one intended to descend&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: Own Work - Program used: Aircraft Situation Editor (ASE))&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this example, I need BER456 to descend to FL100, but I have crossing traffic from the right which would cause a cleared conflict, if I issue a descent clearance directly to FL100 without any conditional instructions. I can use a bit of mathematics here to ensure separation however and issue a clearance nevertheless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both aircraft are travelling at 420kt GS. An aircraft will also descend 1.000ft in 3nm, rule of thumb from every flight instruction book available. To ensure 5nm of lateral separation, I would need a buffer of 2.000ft during descent to the crossing traffic, not factoring in that the other traffic will be on a divergent track anyway. Let's just measure the distance to the HMM for simplicity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instruction to BER456 would be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;R: BER456, when ready descend FL100, cross HMM VOR at FL230 or above (rate of descend 2.000ft/min or less)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;With this instruction, I can issue a clearance to BER456 that will allow the aircraft a continuous descent to FL100, while ensuring minimum separation is kept to the other traffic. Overhead HMM VOR, both aircraft will have 3.000ft of separation. After BER456 has descended a further 2.000ft, it will have 6nm and 1.000ft of separation, making it well clear of a conflict, especially since the traffic is divergent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dirty solution would have been to clear BER456 to FL210 and after 5nm issue another clearance to FL100, but this doubles the frequency time and also interrupts the descent for BER456.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-12T10:49:58.377" LastActivityDate="2015-02-12T10:49:58.377" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9671" PostTypeId="2" ParentId="9653" CreationDate="2014-11-14T00:58:55.110" Score="20" Body="&lt;p&gt;While not an engineer, I do fly aircraft with adjustable nozzles, and I may be able to shed some light on their basic principle of operation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Purpose&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of the nozzle, in subsonic flow, is to constrict the airflow, thus greatly increasing the thrust as it leaves the engine (technically speaking, it converts the gas into a thrust, thereby making the gas generator a jet engine.)  If there was no nozzle, then the gas leaving the turbine would not have nearly the same thrust coming out of the back as it does when the nozzle restricts.  You can think of it like placing your thumb over the end of a hose, the flow is much faster as you restrict the flow of water.  More technically, flow speed increases while the actual pressure decreases--the venturi effect.  However, during afterburning operations, the nozzles have the reverse effect, and closing them actually reduces flow speed.  Thus, during supersonic flow the nozzles actually open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Operation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving the throttle forward on a jet does a few things, it increases fuel, creates more gas, and also restricts the nozzles.  During taxi operations, I'd guess that the nozzles restricting, as you come off the idle stops, have more of an effect on the jet moving than the actual increase in N2.  In fact, were the nozzles not to restrict properly and suddenly open during flight, the jet would fall out of the sky.  Its an actual emergency we practice, because, occasionally, nozzles will malfunction which, in a worst case scenario, can leave you with two useless engines.  However, as with most things, there's a caveat.  When operating in afterburner the nozzles open back up again.  Nozzles that are stuck closed in AB have the same effect that nozzles that are stuck open in mil do--you become a brick.  So essentially, nozzles are only required if your engine is capable of afterburning and generating supersonic flow.  You can't generate thrust with open nozzles below burner, and you can't generate thrust with closed nozzles in burner.  Its just more complexity that non-AB engines don't need, and more that can fail in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Efficiency&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was any reason why commercial aircraft do not have the same engines we do, this would be it.  With the exception of highly inefficient turbojet engines, nearly all commercial aircraft are equipped with turbofan engines, high-bypass turbofans to be precise.  Without getting into the weeds, the high-bypass flow used in modern engines allows them to operate much more efficiently than our engines.  With a high-bypass engine, all flow will remain subsonic, and a fixed exhaust is not only more economical, its also safer because it can't open and reduce thrust.  Fighter aircraft also use turbofans, however, ours are low-bypass, and consume much more fuel than our civilian counterparts.  The benefit is that we are also able to operate in a much more diverse environment: high AoA's, supersonic flow, rapid power fluctuations, etc...  Given our mission the trade off between lost efficiency vs performance gain makes sense. For reference, on the Super Hornet, our engines burn over 38,000pph at MAX.  This kind of inefficiency would quickly bankrupt an airline, because they just don't have the same kind of operational requirements.  Granted, we don't fly around at MAX all the time, but you get the idea.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-14T13:10:41.270" LastActivityDate="2014-11-14T13:10:41.270" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9672" PostTypeId="2" ParentId="9594" CreationDate="2014-11-14T03:11:57.320" Score="3" Body="&lt;p&gt;I'll also add &lt;code&gt;The context&lt;/code&gt;. Or, everything one actually knows in a specific situation to identify a plane :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In real life, there are regions of the globe where you don't find planes a lot. When you know which airplanes are flying in the region, you may identify it even 10 miles away, based on factors like :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the apparent size (compared to its motion) -&gt; It's a white twin engine widebody ? -&gt; 777F of Air France landing in Africa&lt;/li&gt;&#xA;&lt;li&gt;the visible colors -&gt; It's the An28 of some airline (Completely Black)&lt;/li&gt;&#xA;&lt;li&gt;the time : Afternoon, a cyan 747 taking off from CDG -&gt; Korean Air&lt;/li&gt;&#xA;&lt;li&gt;events : what looks like a shiny 747-200 at Orly -&gt; Air Force One during some international summit..&lt;/li&gt;&#xA;&lt;li&gt;etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That also applies in the books you read : in the old days of world wars, you don't have much planes flying around unless it's foo or friend. So you can expect to encounter less different types of aircraft. Was-it a F4, a Spitfire or a Stutka, those could be identified from far away, while beeing just assumptions, fighter pilots were rarely mistaken.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Close combat like those describes by veterans : look at their palms : you rarely see a chased plane from behind, mostly from above for example : this gives several opportunities to read anything written big on the plane, both in bright and dark condition depending on the aircraft relative position to the sun. Changing luminosity helps reading aircraft numbering (you can experiment this during acrobatic airshows, looking at the plane from the ground)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;And intelligence : During world war, you had spies, often civilians who gather information about the enemy's equipment. So, sometimes, fighter pilots knews how many enemy warbirds they may encounter, the models, the colors/markings, etc. and even the registrations, well before meeting them someday, if ever.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Finally : IL2 Sturmovik is a game. It's purpose is to entertain. If you were playing such game and expect to identify a plane 6 miles away just by looking at the screen, you may just barely notice a pixel dot and come closer.. closer... until it's too late. Arraagh ! X( (same thing applies to &lt;em&gt;any&lt;/em&gt; game)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A game is not a game (and doesn't sell well) if you don't enjoy it, so, helping you identify friends and threats adds in the gameplay even if it's not really realistic.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastActivityDate="2014-11-14T03:11:57.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9673" PostTypeId="2" ParentId="9652" CreationDate="2014-11-14T07:43:34.563" Score="6" Body="&lt;p&gt;While some pressurized aircraft use oxygen generators as others have described, others use pressurized (up to 3000 psi) gaseous oxygen canisters. An engineer who designs such systems showed me how central oxygen systems work, but I believe there are &lt;a href=&quot;http://beaerospace.com/products/oxygen-systems/passenger-oxygen-systems/pulseox-oxygen/&quot; rel=&quot;nofollow&quot;&gt;smaller units (per seat group)&lt;/a&gt; on B787s and A350 XWBs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They would carry at least 15 minutes of oxygen, but how long it lasts depends on how many people are using masks.&lt;/p&gt;&#xA;" OwnerUserId="2272" LastEditorUserId="2272" LastEditDate="2014-11-14T19:20:33.460" LastActivityDate="2014-11-14T19:20:33.460" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9674" PostTypeId="2" ParentId="9639" CreationDate="2014-11-14T10:22:19.320" Score="10" Body="&lt;p&gt;After researching myself and asking a colleauge I found out that the L-1011(one of my favorites) &#xA;&lt;img src=&quot;https://i.stack.imgur.com/BLXcb.jpg&quot; alt=&quot;TriStar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the DC-10 (thanks to @UnrecognizedFallingObject for the comment)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WQpoz.jpg&quot; alt=&quot;DC10&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;had persons elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Tristar and the DC-10&#xA;The purpose are to connect the Main Deck with the personnel-cabin or the Lounge.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3HeYw.jpg&quot; alt=&quot;DC10&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aCRae.jpg&quot; alt=&quot;TriStar Lounge&quot;&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/US/1997-06-26-US.pdf&quot; rel=&quot;noreferrer&quot;&gt;The Mechanism as &quot;@ratchet freak&quot; stated in the comment is an &quot;rack and pinion gears&quot; elevator with 1 electric motor with 1 outer shaft (primary) and 1 inner shaft, as stated in an report of an incident with one of these elevators.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the A380 there is an elevator to connect the 2 main decks, but this one is only for trolleys.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sdO4s.jpg&quot; alt=&quot;A380&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional Information on mechanism of elevator:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Drive System&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Each lift is operated by an independent drive unit. Each drive 400-cycle, three-phase, &#xA;  alternating current (AC) motors. Each motor is connected to a gearbox with &#xA;  counter-rotating drive shafts and sprockets for a chain drive. The drive shafts are &#xA;  operated by a common worm gear within the gearbox. In the&#xA;  event of one motor failure, the other motor will drive the lift at&#xA;  half-speed. Two, independent, continuous loop, bicycle-type chains taking power from the&#xA;  dual-output sprockets on the drive units actively drive each lift.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Woqdb.png&quot; alt=&quot;DriveUnit&quot;&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Limit Switches&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The range of travel of the lifts is controlled by limit switches installed&#xA;  within the wire duct attached to the forward side of one of the vertical lift&#xA;  tracks. There are two sets of two limit switches for each lift:&#xA;  one set located in the service center and one set in the lower galley.&#xA;  One switch is a normal stop switch and the other limit switch is for&#xA;  overtravel in the event the normal switch fails to operate. &#xA;  The limit switches are actuated by a cam plate mounted on the side of the lift.&#xA;  The cam plate has a machined offset to prevent actuation of the&#xA;  overtravel limit switch unless the normal switch fails to operate. In&#xA;  addition to the limit switches, mechanical stops are installed in the&#xA;  vertical lift tracks to stall and shut off the gear motors if both&#xA;  limit switches malfunction.&#xA;  &lt;img src=&quot;https://i.stack.imgur.com/4nWMx.jpg&quot; alt=&quot;ElectricSwitches&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airdisaster.com/reports/ntsb/AAR82-01.pdf&quot; rel=&quot;noreferrer&quot;&gt;Further and detailed Information can be found here in this Incident.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="3734" LastEditDate="2014-11-14T14:02:49.157" LastActivityDate="2014-11-14T14:02:49.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9675" PostTypeId="2" ParentId="9653" CreationDate="2014-11-14T10:22:20.910" Score="4" Body="&lt;p&gt;Peter Kämpf already gave good long answer with nice diagrams. tl;dr, the thing boils down to subsonic and supersonic flow behaving differently. The goal is to increase the exhaust speed. For subsonic flow you achieve that by restricting it, but for supersonic stream you have to expand it. So supersonic engines (and supersonic exhaust speed is rarely reached without afterburner) need variable area nozzle, subsonic ones (all airliner engines except Concorde) not.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-11-14T10:22:20.910" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9676" PostTypeId="1" AcceptedAnswerId="9677" CreationDate="2014-11-14T10:44:14.217" Score="32" ViewCount="21269" Body="&lt;p&gt;I've seen that airplanes are connected to some wire like in the picture. What is it's name and what is it for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JzaFU.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3476" LastEditorUserId="97" LastEditDate="2014-11-15T01:39:13.147" LastActivityDate="2016-03-11T05:48:13.443" Title="What is the cable connected to a plane for?" Tags="&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9677" PostTypeId="2" ParentId="9676" CreationDate="2014-11-14T10:49:42.890" Score="36" Body="&lt;p&gt;This is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_support_equipment#Ground_power_units&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;ground power unit&lt;/strong&gt;&lt;/a&gt; (GPU) which supplies the aircraft with electricity while the generators or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;noreferrer&quot;&gt;auxiliary power unit&lt;/a&gt; (APU) are not running. This is important especially during boarding, when the cabin lighting needs to remain on for passengers to embark or disembark. The GPU is also used to start the APU, which in turn provides electricity to start the engines and the generators.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A ground power unit (GPU) is a vehicle capable of supplying power to aircraft parked on the ground. Ground power units may also be built into the jetway, making it even easier to supply electrical power to aircraft. Many aircraft require 28 V of direct current and 115 V 400 Hz of alternating current. The electric energy is carried from a generator to a connection on the aircraft via 3 phase 4-wire insulated cable capable of handling 261 amps (90 kVA). These connectors are standard for all aircraft, as defined in ISO 6858.&#xA;  &lt;br&gt;Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_support_equipment#Ground_power_units&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Related Questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2605/can-large-airliners-be-operated-without-ground-support/&quot;&gt;Can large airliners be operated without ground support?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1959/how-are-turbine-engines-started/&quot;&gt;How are turbine engines started?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-11-14T16:59:52.120" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9678" PostTypeId="2" ParentId="9676" CreationDate="2014-11-14T10:50:10.037" Score="10" Body="&lt;p&gt;It provides power to the plane for when the engines and APU are not running while sitting at the gate to save fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It allows the cabin lights to remain on so the passengers aren't tripping over each other as they board. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power may also be used to start the APU that will in turn provide the power needed to start the main engines.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-11-14T10:50:10.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9679" PostTypeId="2" ParentId="9643" CreationDate="2014-11-14T11:37:01.963" Score="6" Body="&lt;p&gt;It completely depends on the condition. Just because you're denied a FAA medical it doesn't automatically mean you can't get one to operate in another country. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, colour-blind pilots can fly up to First Officer level in Australia, and we have no mandatory retirement age. But we are stricter on things like head injuries. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-11-14T11:37:01.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9680" PostTypeId="1" AcceptedAnswerId="9686" CreationDate="2014-11-14T12:45:53.830" Score="57" ViewCount="43885" Body="&lt;p&gt;It seems that most airliners put the engines below the wings, i.e. the Boeing 7*7 series and the Airbus A3** series. This requires long (heavy) landing gear, and the engines are close to the ground which may cause damage to the engines (ingest debris) or the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F6xmR.jpg&quot; alt=&quot;FOD&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why not mount the engines &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-72&quot; rel=&quot;noreferrer&quot;&gt;above the wings&lt;/a&gt;&lt;/strong&gt;? In addition to the shorter (lighter, stronger) landing gear, the plane would be easier to service and embark / disembark. &lt;strong&gt;What are the major disadvantages to having the engines above the wings for civilian airliners?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question &lt;a href=&quot;https://aviation.stackexchange.com/questions/1397/how-does-the-mounting-location-of-a-jet-engine-affect-aircraft-performance&quot;&gt;&lt;em&gt;&quot;How does the mounting location of a jet engine affect aircraft performance?&quot;&lt;/em&gt;&lt;/a&gt; addresses the performance issues affecting engine placement but answers do not cover over-wing placement extensively and focus only on performance and not other operational issues or design advantages.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2018-08-23T16:39:47.203" Title="Why not mount airliner jet engines above the wings?" Tags="&lt;aircraft-design&gt;" AnswerCount="9" CommentCount="15" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9681" PostTypeId="1" AcceptedAnswerId="9904" CreationDate="2014-11-14T12:46:58.973" Score="22" ViewCount="42871" Body="&lt;p&gt;I wonder if it is possible to download a database with waypoints, navaids, airports and airways between them. I've been working with AIP documents but it's difficult to get raw information from them and they only have information about waypoints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I happened to find skyvector.com and I thought there would be an easier way to obtain that amount of information.&lt;/p&gt;&#xA;" OwnerUserId="4250" LastEditorUserId="19" LastEditDate="2017-05-05T09:05:17.177" LastActivityDate="2020-12-21T17:51:44.090" Title="Where to find a waypoints/fixed points, navaids and airports database?" Tags="&lt;icao&gt;&lt;website&gt;&lt;datasets&gt;&lt;navaids&gt;&lt;vor&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9682" PostTypeId="1" AcceptedAnswerId="9684" CreationDate="2014-11-14T14:43:06.907" Score="8" ViewCount="10865" Body="&lt;p&gt;I'm teaching an introductory course in fluid dynamics and I'd like to show some &quot;real&quot; data regarding drag and lift forces on an airfoil. It is easy to find data on the geometry of typical airfoils, but I was not so lucky with $C_L = f(airfoil, Re, i)$ and $C_D = f(airfoil, Re, i)$ ($Re$ is the Reynolds number and $i$ the angle of attack). I'm looking for that kind of diagram or data :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yEZhd.gif&quot; alt=&quot;Graphs of C_L vs. alpha, and C_L vs. C_D for NACA 4412&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data for commonly known aircraft would be great (B737, B747, A320, A380).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks.&lt;/p&gt;&#xA;" OwnerUserId="1655" LastEditorUserId="1696" LastEditDate="2015-12-14T17:39:18.353" LastActivityDate="2018-04-02T13:03:47.817" Title="Where can I find data tables for lift and drag coefficients of airliners?" Tags="&lt;aerodynamics&gt;&lt;datasets&gt;&lt;drag&gt;&lt;lift&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9683" PostTypeId="2" ParentId="7705" CreationDate="2014-11-14T15:03:41.273" Score="1" Body="&lt;p&gt;The definitive reference in the US is the A/FD. The &lt;a href=&quot;http://aeronav.faa.gov/afd/13NOV2014/SE_front_13NOV2014.pdf&quot; rel=&quot;nofollow&quot;&gt;A/FD shows&lt;/a&gt; the &quot;operating agency&quot; of each airport if it isn't a civil, public airport:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airports within this directory are classified into two categories,&#xA;  Military/Federal Government and Civil airports open to the general&#xA;  public, plus selected private use airports. The operating agency is&#xA;  shown for military, private use and joint civil/military airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you don't see an operating agency, it's civil. If you do, then you need to consult the list of possible agencies. For example, &lt;a href=&quot;http://aeronav.faa.gov/afd/13NOV2014/se_168_13NOV2014.pdf&quot; rel=&quot;nofollow&quot;&gt;KATL&lt;/a&gt; has no operating agency so it's civil and public; &lt;a href=&quot;http://aeronav.faa.gov/afd/13NOV2014/se_183_13NOV2014.pdf&quot; rel=&quot;nofollow&quot;&gt;KMGE&lt;/a&gt; (Dobbins ARB) has the operating agency &quot;AFRC (AR ARNG)&quot; listed in the A/FD which according to &lt;a href=&quot;http://aeronav.faa.gov/afd/13NOV2014/SE_front_13NOV2014.pdf&quot; rel=&quot;nofollow&quot;&gt;the legend&lt;/a&gt; means &quot;Air Force Reserve Command (US Army Reserve US Army National Guard)&quot;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-14T15:03:41.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9684" PostTypeId="2" ParentId="9682" CreationDate="2014-11-14T15:32:13.573" Score="7" Body="&lt;p&gt;My first thought was: Abbott-Doenhoff. They wrote a book with lots of measurement data, and you can find it &lt;a href=&quot;http://aeroknowledge77.files.wordpress.com/2011/09/58986488-theory-of-wing-sections-including-a-summary-of-airfoil-data.pdf&quot;&gt;here&lt;/a&gt;. Of course, this was all long ago, but public data for the airfoils of today's airliners are not published.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of data is also freely available in old NACA and NASA reports, however, you need to know what data you want to search for it efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to focus on glider airfoils, the Stuttgarter Profilekatalog would be my next source, but unfortunately there are still people who want to make money from it even though the work was financed with public money. This is also quite old, and more modern airfoils from Delft University are similarly restricted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another great source is the &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/coord_database.html&quot;&gt;UIUC airfoil database&lt;/a&gt;, but here the focus is on section data and not on polars. But it contains many useful links with airfoil data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is always &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot;&gt;XFOIL&lt;/a&gt;: Feed it with the coordinates, and you get very good simulations of what a wind tunnel would measure, at least as long as most of the flow is still attached. Lots of plotting functions will help to uncover what is going on in much more detail than any wind tunnel data could ever hope to do.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-11-14T15:32:13.573" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9685" PostTypeId="2" ParentId="9680" CreationDate="2014-11-14T15:33:56.237" Score="18" Body="&lt;p&gt;If we ignore the other engine placement options considered in the linked question, we can compare only over vs underwing placement. I'm no expert but here are some factors that occur to me:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Underwing simplifies engine access, the engine is close to the ground. Since most engines are mounted this way it may be that engine-designers optimize placement of components with this in mind (though engines are often produced for a specific plane)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Underwing mounting means that gravity helps hold the engine in position laterally. For overwing placement, the opposite is true and you might need a slightly stronger pylon and wing-spars?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Overwing placement causes the torque on the wing from the weight of the engine to act in the same direction as the torque from thrust, underwing location reduces total torque - though this may not be significant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engines are at maximum thrust at take-off. An overwing engine at maximum thrust would probably be more likely to exert a torque on the airframe that opposes lifting the nose for take off. I'm not sure if this is good or bad but it seems wrongish.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Overwing placement certainly decreases the risk of FOD but may impede passengers view and increase noise.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft landing gear may have to be a certain height anyway to keep the tail clear of the runway during take-off rotation and to absorb landing forces over a longer distance. This may not be significant as there are large aircraft with very short landing gear (e.g. some military and civilian transport aircraft). Perhaps they pay a penalty for this.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are probably more airliners than large airports, so it may be thought better to remove FO from runways than make general airliners more FOD-proof.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/64E50.jpg&quot; alt=&quot;FO collected from runway&quot;&gt;  &lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.airport-supply.at/index.php?page=parts_details&amp;amp;products_id=25&quot; rel=&quot;noreferrer&quot;&gt;source: Bartosch&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-11-15T09:10:31.547" LastActivityDate="2014-11-15T09:10:31.547" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9686" PostTypeId="2" ParentId="9680" CreationDate="2014-11-14T15:36:55.307" Score="51" Body="&lt;p&gt;&lt;em&gt;Maintenance&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the engines below the wing makes them fairly easy to access, even if some kind of lift is needed. Putting them above the wing would make them much harder to get to. Dropped a tool? Better start on that wing repair too. This includes both general access to the engine and the procedures for removing and installing the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Structure&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine below the wing is fairly stable, since it is hanging from above. It naturally wants to keep hanging downwards. Mounting the engine above the wing would be less stable. It naturally wants to tip over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Noise&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine is under the wing, it helps to block some of the noise from at least the mid cabin. An engine above the wing would expose much more of the cabin to noise. It could reduce the ground noise while in flight, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Aerodynamics&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The top of the wing is the most sensitive part aerodynamically. This is why items like fuel tank access panels are placed on the bottom. Having an engine and pylon on top would affect the flow over the top of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Safety&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines falling off the wings tends to be a &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al_Flight_1862&quot;&gt;bad&lt;/a&gt; &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20110518-1&quot;&gt;thing&lt;/a&gt;. But if they were above the wing, they would tend to fall down onto the wing, which would still not be good. It would be harder to have then break away in a crash. Also, in the event of an uncontained failure, the wing would not provide any protection to the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of course there are benefits, such as the reduced noise, less ground clearance required, no interference between the jet blast and the flaps, and less chance of FOD being ingested. As new engines get larger fan diameters, the constraints become more difficult. Some concepts of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_X-48&quot;&gt;blended wing body&lt;/a&gt; design put the engines on top of the body. But for the current design of aircraft, the benefits of having the engines below the wing are greater than those of the alternatives.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-11-14T15:45:48.503" LastActivityDate="2014-11-14T15:45:48.503" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9687" PostTypeId="2" ParentId="9656" CreationDate="2014-11-14T16:12:30.013" Score="4" Body="&lt;p&gt;I'm a USPA AFF, tandem, and static line instructor.  Your signed and completed A-License Proficiency Card is valid and USPA will process it without the stamp.  You only need the stamp if you want to go to another dropzone and use your card as a temporary license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The proficiency card is only valid for 60 days after the date it was completed, so don't waste time sending it in.  The last I heard, USPA is taking 3-4 weeks to process license applications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit to add:  Don't send in the actual card.  You can mail a photocopy, fax it in, or scan it and email it to membership@uspa.org.  Faxing or emailing will get you your official license a few days faster.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastEditorUserId="2696" LastEditDate="2014-11-14T18:17:19.543" LastActivityDate="2014-11-14T18:17:19.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9688" PostTypeId="2" ParentId="9680" CreationDate="2014-11-14T16:14:17.333" Score="45" Body="&lt;p&gt;There was one design with overwing engines: The &lt;a href=&quot;http://en.wikipedia.org/wiki/VFW-Fokker_614&quot; rel=&quot;noreferrer&quot;&gt;VFW-614&lt;/a&gt;. The number was chosen because it was the 4th project to be started in 1961 by the Vereinigte Flugzeugwerke (VFW). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nlJPs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine placement had several advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;less risk of ingesting foreign objects&lt;/li&gt;&#xA;&lt;li&gt;less noise during take-off and landing, at least for the people on the ground&lt;/li&gt;&#xA;&lt;li&gt;less trim change with power changes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But the disadvantages (cabin noise and engine access) were the reason why this engine placement never took off. Also, low engines can get their fuel without pumps, just by gravity. However, pilots who flew both the 614 and the Boeing 737 told me that the 614 was more pleasant to fly since it needed no trim changes when the power setting was changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placing the engine forward of the wing helps to dampen flutter, but then the main advantage of overwing placement, reduced noise footprint, is lost. Todays engines are mostly placed ahead of the wing for that reason, and below it so they are out of view for the passengers. Placing the engine directly under the wing would help with feeding it pre-compressed air, but again the forward location makes little difference.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-15T20:57:26.380" LastActivityDate="2014-11-15T20:57:26.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9689" PostTypeId="2" ParentId="9680" CreationDate="2014-11-14T16:15:22.533" Score="15" Body="&lt;p&gt;I painted the new pictures myself but took the text from an &lt;a href=&quot;http://www.airliners.net/forum/viewtopic.php?t=764855&quot; rel=&quot;nofollow noreferrer&quot;&gt;external source&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You can see with the engine mounted over the wing, you have the&#xA;  centerline of thrust located above the longitudinal axis of the&#xA;  aircraft. This creates a nose-down pitching moment about the lateral&#xA;  axis, which is at the center of gravity (CG). While the weight of the&#xA;  engine does help counteract it, it must also be countered by an&#xA;  increased amount of downward lift created by the horizontal stab (a&#xA;  greater tail-down moment).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FYQgR.png&quot; alt=&quot;JetDown&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PWzLq.png&quot; alt=&quot;JetUp&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="1289" LastEditDate="2018-01-03T20:43:01.347" LastActivityDate="2018-01-03T20:43:01.347" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9690" PostTypeId="2" ParentId="9642" CreationDate="2014-11-14T16:30:29.523" Score="0" Body="&lt;p&gt;In the ICAO PANS ATM (Doc 4444) (*) the vertical separation is specified as &lt;code&gt;1000ft (or 2000ft)&lt;/code&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;5.3.2 Vertical separation minimum&lt;/p&gt;&#xA;&lt;p&gt;The vertical separation minimum (VSM) shall be:&lt;/p&gt;&#xA;&lt;p&gt;a) a nominal 300 m (1000 ft) below FL 290 and a nominal 600 m (2000 ft) at or above this level, except as provided for in b) below; and&lt;/p&gt;&#xA;&lt;p&gt;b) within designated airspace, subject to a regional air navigation agreement: a nominal &amp;gt; 300 m (1000 ft) below FL 410 or a higher level where so prescribed for use under &amp;gt; specified conditions, and a nominal 600 m (2000 ft) at or above this level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The minimum horizontal separation mimumum is &lt;code&gt;5 NM&lt;/code&gt; for flights under radar control:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;8.7.3 Separation minima based on ATS surveillance systems&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;8.7.3.1 Unless otherwise prescribed in accordance with 8.7.3.2, 8.7.3.3 or 8.7.3.4, or  chapter 6 (with respect to independent and dependent parallel approaches), the horizontal separation minimum based on radar and/or ADS-B and/or MLAT systems shall be 9.3 km (5.0 NM).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The approach and departure phases of flight has some small deviations, e.g. small aircraft behind heavy aircraft have to keep &lt;code&gt;6 NM&lt;/code&gt; horizontal separation because of wake vortexes.&lt;/p&gt;&#xA;&lt;p&gt;(*) Unfortunately I couldn't find the official Doc 4444 on the ICAO website.&lt;/p&gt;&#xA;" OwnerUserId="3859" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-14T16:39:30.627" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9691" PostTypeId="2" ParentId="8749" CreationDate="2014-11-14T16:37:23.363" Score="4" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.economist.com/&quot; rel=&quot;nofollow&quot;&gt;The Economist&lt;/a&gt; data in 2012 &lt;a href=&quot;http://www.economist.com/node/21543195&quot; rel=&quot;nofollow&quot;&gt;showed that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Over a third of the world's airline fleet is now rented (see chart)&#xA;  and the proportion is likely to keep growing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article has some interesting background about the companies involved and the advantages of leasing vs. buying, which one Delta source compares to housing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Delta's fleet planner] argues that big airlines are better off buying planes and keeping&#xA;  them for their full lifespan of 30 years or so. Like houses, then,&#xA;  buying is cheaper than renting in the long term.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-14T16:37:23.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9692" PostTypeId="2" ParentId="3268" CreationDate="2014-11-14T17:11:16.637" Score="3" Body="&lt;p&gt;I spent a bit of time Googling this and I couldn't find any other country that systematically arms pilots using a &lt;em&gt;public, open program&lt;/em&gt; like the FFDO. What countries might do in secret is anyone's guess, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most obvious candidate is Israel, since El Al is famous for its tough and often very visible &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al#Security&quot; rel=&quot;nofollow&quot;&gt;security&lt;/a&gt;. There are &lt;a href=&quot;http://news.bbc.co.uk/1/hi/world/americas/2097352.stm&quot; rel=&quot;nofollow&quot;&gt;many&lt;/a&gt; &lt;a href=&quot;http://www.ibtimes.com/el-al-israel-airlines-safest-airline-world-also-worst-time-performer-1556712&quot; rel=&quot;nofollow&quot;&gt;reports&lt;/a&gt; that El Al uses sky marshals (&lt;a href=&quot;http://www.dailymail.co.uk/news/article-2141289/Armed-air-marshals-patrolled-flights-Gatwick-U-S-spooks-worked-thwart-underpants-bomb-plot.html&quot; rel=&quot;nofollow&quot;&gt;one article&lt;/a&gt; says &quot;on all flights&quot;), but I couldn't find any mention of the pilots themselves being armed. That doesn't mean they aren't armed, but it at least suggests that there is no public program in Israel comparable to the FFDO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same reason, the lack of information about similar publicly recognized programs in other countries strongly suggests that they don't exist.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-14T17:11:16.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9693" PostTypeId="1" AcceptedAnswerId="9694" CreationDate="2014-11-14T17:46:39.333" Score="9" ViewCount="938" Body="&lt;p&gt;I am an aviation enthusiast from India. I am 24 now and want to be a hobby pilot after 1 or 2 years (I need to save money to afford training).  I want to move up to twin engine aircraft as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I have fair amount of free time and can understand the concepts clearly with no time pressure, &lt;strong&gt;what should I start doing now&lt;/strong&gt; that will help me tremendously when I train to be a pilot (reading books or doing any other stuff)?  What should be my plan of action?&lt;/p&gt;&#xA;" OwnerUserId="4256" LastEditorUserId="62" LastEditDate="2015-12-14T18:39:58.390" LastActivityDate="2017-08-07T18:27:35.383" Title="What can I do to prepare for private pilot training? (India)" Tags="&lt;flight-training&gt;&lt;ppl&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9694" PostTypeId="2" ParentId="9693" CreationDate="2014-11-14T18:43:21.400" Score="10" Body="&lt;p&gt;It's hard to give you specific advice for India because I'm not familiar with the regulations and standards there (your best bet would be to give the DGCA a call and ask if they have any publications you can review).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broadly speaking all countries are going to expect you to know much of the same material however (because all airplanes essentially fly the same way). Along those lines, &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA publishes some of the best flight training resources out there&lt;/a&gt;, and it's all available online for free.&lt;br&gt;&#xA;I would recommend two of the publications to anyone considering flight training:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Airplane Flying Handbook&lt;/a&gt;&lt;br&gt;&#xA;This is where I'd generally suggest starting - a basic &quot;How does all this flying stuff work?&quot; textbook on a par with any of the commercially-produced materials.&lt;br&gt;&#xA;Details on specific regulations, procedures, how to read charts, etc. may vary, but all of the material on aerodynamics, systems, flight controls, and maneuvers will be applicable.&lt;br&gt;&#xA;If you're interested in helicopters &lt;a href=&quot;http://](https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/)&quot; rel=&quot;nofollow noreferrer&quot;&gt;there's a Helicopter Flying Handbook&lt;/a&gt; as well.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://(http://www.faa.gov/air_traffic/publications/media/aim.pdf)&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Aeronautical Information Manual&lt;/a&gt; (direct PDF link)&lt;br&gt;&#xA;This will be less useful to you as it's written with US regulations in mind (and stuff like aeronautical charting is probably different in India than it is in the US), but again there are large sections that are broadly applicable: Chapters 1, 2, and 8 in particular.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In addition to reading you can gain some experience using simulators &lt;em&gt;if you use them effectively&lt;/em&gt; - even relatively inexpensive home simulation software &amp;amp; equipment can be helpful, though it's not a substitute for the real thing. &lt;a href=&quot;https://aviation.stackexchange.com/q/738/62&quot;&gt;We've got a good Q&amp;amp;A on using simulators to help in training&lt;/a&gt; which addresses some of the strengths and weaknesses of learning in a simulator. To help keep you from developing bad habits you would have to un-learn in a real airplane there are also &lt;a href=&quot;http://www.flyaoamedia.com/aviator-90/&quot; rel=&quot;nofollow noreferrer&quot;&gt;companies providing what's effectively a private pilot flight course via simulators&lt;/a&gt; for free, and that will help you get started doing things right - following all the procedures as you would for a real airplane.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="62" LastEditDate="2017-08-07T18:27:35.383" LastActivityDate="2017-08-07T18:27:35.383" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9695" PostTypeId="1" AcceptedAnswerId="9700" CreationDate="2014-11-14T19:44:31.973" Score="20" ViewCount="3961" Body="&lt;p&gt;According to &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.205&quot;&gt;FAR 91.205 (d)(6)&lt;/a&gt;, one instrument required for IFR is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A clock displaying hours, minutes, and seconds with a sweep-second&#xA;  pointer or digital presentation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why is it necessary to time things in the cockpit, or know the time?&lt;/p&gt;&#xA;" OwnerUserId="3493" LastEditorUserId="65" LastEditDate="2014-11-14T21:08:54.937" LastActivityDate="2014-11-17T15:07:25.713" Title="Why is a clock necessary for IFR?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-instruments&gt;&lt;clock&gt;&lt;time&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9696" PostTypeId="2" ParentId="9695" CreationDate="2014-11-14T20:06:53.673" Score="5" Body="&lt;p&gt;Some procedures require timing, e.g. holding over a fix or NAVAID is usually done in 1min legs. Precise timing is necessary here. Some clearances can also contain a time (e.g. release valid until, revised approach time, etc), where correct timing is necessary.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2014-11-14T20:06:53.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9697" PostTypeId="2" ParentId="9695" CreationDate="2014-11-14T20:07:10.610" Score="11" Body="&lt;p&gt;In IFR the pilot needs to have a second-accurate time indicator for a variety of maneuvers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the standard holding pattern is 1 minute turns and 1 minute straight legs. Having the number of seconds allows the pilot to fly these maneuvers accurately.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="97" LastEditDate="2014-11-15T18:16:35.233" LastActivityDate="2014-11-15T18:16:35.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9698" PostTypeId="2" ParentId="9695" CreationDate="2014-11-14T20:12:34.187" Score="8" Body="&lt;p&gt;When flying under IFR in IMC you have no external visual references, so there are a number of reasons you may need to time something:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some approaches require you to be able to time them.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dZdz0.png&quot; rel=&quot;noreferrer&quot;&gt;VOR approaches&lt;/a&gt; have a table of times from the final approach fix to the missed approach point at a given groundspeed: Since you have no other way to judge distance over the ground you must use the clock.&lt;/li&gt;&#xA;&lt;li&gt;A &quot;normal&quot; holding pattern consists of one-minute legs with one minute (180-degree) turns at each end. &lt;/li&gt;&#xA;&lt;li&gt;Turns under IFR are assumed to be made at &quot;standard rate&quot; (3 degrees per second).&lt;br&gt;&#xA;If your DG fails you can make &quot;timed turns&quot; with the turn coordinator, a compass, and a clock (30 seconds for a 90-degree turn, one minute for a 180, 2 minutes for a 360) and come out pretty close to your intended course, without being thrown off by compass lead/lag or acceleration errors.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There may be others but these are the ones that spring immediately to mind.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-14T20:12:34.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9699" PostTypeId="2" ParentId="6341" CreationDate="2014-11-14T20:14:56.583" Score="2" Body="&lt;p&gt;From the Helicopter ATP PTS (Didn't look at FW):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;C. TASK: PRECISION INSTRUMENT APPROACHES&#xA;REFERENCES: Part 61; AC 61-27; Pilot's Operating Handbook, RFM, AIM; Instrument Approach Procedure Charts.&#xA;NOTE: Two precision approaches must be accomplished in actual or simulated instrument conditions.&#xA;NOTE: If the installed equipment and data base is current and qualified for IFR flight and LPV approaches, an LPV approach can be flown to demonstrate precision approach proficiency if the LPV DA is equal to or less than 300 feet HAT.&lt;/p&gt;&#xA;" OwnerUserId="4260" LastActivityDate="2014-11-14T20:14:56.583" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9700" PostTypeId="2" ParentId="9695" CreationDate="2014-11-14T20:20:15.120" Score="32" Body="&lt;p&gt;There are several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For departure clearances. An IFR clearance may have a &lt;a href=&quot;http://groundschool.prepware.com/cgi-bin/faraim.pl?subsection_id=215&quot;&gt;void or release time&lt;/a&gt; so that clearance is only valid between certain times.&lt;/li&gt;&#xA;&lt;li&gt;For holding pattern legs. A &lt;a href=&quot;http://en.wikipedia.org/wiki/Holding_(aeronautics)&quot;&gt;standard holding pattern&lt;/a&gt; is based on a time of one minute at or below 14,000' MSL and 1.5 minutes above 14,000' MSL on the inbound leg.&lt;/li&gt;&#xA;&lt;li&gt;For holding pattern clearances. Holding instructions include an &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0406.html&quot;&gt;EFC (expect further clearance) time&lt;/a&gt;, so that if you have a communication failure while holding then you know when you can safely leave the hold and start an approach.&lt;/li&gt;&#xA;&lt;li&gt;For &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0607.html&quot;&gt;timed approaches&lt;/a&gt;, where an aircraft is cleared to start an approach at a specific time&lt;/li&gt;&#xA;&lt;li&gt;For timed turns. A &lt;a href=&quot;http://en.wikipedia.org/wiki/Standard_rate_turn&quot;&gt;standard rate turn&lt;/a&gt; is 360 degrees in 2 minutes, so with only a timer and a turn coordinator you can turn a specific number of degrees.&lt;/li&gt;&#xA;&lt;li&gt;For en route reporting and general time/distance calculations. Especially in a non-radar environment (i.e. when ATC can't see you on radar) you may be required to give ATC actual or estimated times for passing certain fixes. (This is not strictly IFR only, but it's still relevant.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All of these scenarios are discussed in detail in the FAA's &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot;&gt;Instrument Flying Handbook&lt;/a&gt; and in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/ATpubs/AIM/index.htm&quot;&gt;AIM&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="3504" LastEditDate="2014-11-17T15:07:25.713" LastActivityDate="2014-11-17T15:07:25.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9702" PostTypeId="1" CreationDate="2014-11-14T23:04:47.803" Score="1" ViewCount="400" Body="&lt;p&gt;Is the sweep angle of an inverted wing zero degrees, when the angle between the fuselage and the inverted delta wing is 90 degrees? Or is it different because the span of the wing isn't constant over the chord.&lt;/p&gt;&#xA;" OwnerUserId="4199" LastActivityDate="2014-11-17T23:51:51.333" Title="Is the sweep angle of an inverted wing zero degrees?" Tags="&lt;wing&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9703" PostTypeId="1" CreationDate="2014-11-14T23:06:06.990" Score="17" ViewCount="14255" Body="&lt;p&gt;The startup process in many military aircraft is, complicated, to say the least.&lt;/p&gt;&#xA;&lt;p&gt;It takes a lot longer than most would think. An F-16 from cold is required to be able to scramble within 5 minutes if on alert (armed, fueled, and pilot ready), 15 minutes if not.&lt;/p&gt;&#xA;&lt;p&gt;I also know that during the Cold War when the situation was expected to deteriorate, they could deploy B-52's to all runways (civilian airports included) that were longer than 9,000 feet, just sitting there with engines running ready to go. (Terrifying to think about...)&lt;/p&gt;&#xA;&lt;p&gt;I also found this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Default NATO QRA alert time is 15 minutes (in DEFCON 5), although the local CRC can lower that to ten (DEFCON 4), five (DEFCON 3) or even two minutes (DEFCON 2) depending on current state of affairs.&lt;/p&gt;&#xA;&lt;p&gt;At 5 minutes (DEFCON 3), the engines would be running idle 24/7, at 2 minutes (DEFCON 2) there are pilots in the cockpit 24/7.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Anyways, an F-16 can scramble in 5 minutes. But an F-22 has an automated start process. IIRC, the checklist is something like...&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Master Switch On.&lt;/li&gt;&#xA;&lt;li&gt;Throttles Forward to idle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;I understand that this may be classified, but I was wondering if anyone can put me in the ballpark.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-08-17T21:42:52.333" Title="How fast can an F-22 scramble?" Tags="&lt;military&gt;&lt;takeoff&gt;&lt;f-22&gt;&lt;fighter&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9704" PostTypeId="1" AcceptedAnswerId="9711" CreationDate="2014-11-15T01:33:30.577" Score="13" ViewCount="1422" Body="&lt;p&gt;At a busy airport, &lt;a href=&quot;http://en.wikipedia.org/wiki/Bovingdon_stack&quot;&gt;up to a dozen&lt;/a&gt; aircraft waiting to land may fly the same holding pattern at the same time, separated vertically by 1,000ft. &amp;mdash; a stack. Some ATC towers have dedicated Stack Controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's all very routine, but have there ever been any instances of incidents or accidents in stacks?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the layman, it might seem like stacks could be hazardous &amp;mdash; e.g. what if a plane in the middle of a stack lost an engine?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2019-10-23T23:59:39.720" Title="Have there ever been any accidents within holding stacks?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;engine-failure&gt;&lt;incidents&gt;&lt;holding&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9705" PostTypeId="2" ParentId="9325" CreationDate="2014-11-15T02:43:19.270" Score="12" Body="&lt;p&gt;&lt;strong&gt;How Are Modern Fighter Aircraft Controlled?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F16 was the first US military aircraft to be designed around the revolutionary fly-by-wire concept.  This meant there were no direct mechanical linkages between the cockpit and major control surfaces, and that all pilot input was electronically carried to the hydraulic system via wire.  However, since the F16 burst into the scene, there have been further major advancements in aircraft systems design.  Late Gen 4 aircraft, such as the F/A 18 Super Hornet, are designed around a concept now called &lt;em&gt;control-by-wire&lt;/em&gt;.  Control-by-wire aircraft not only have removed mechanical linkages to the hydraulic system, but now the pilot is only a voting member.  This means that all input is received by a computer bank that then computes what it &lt;em&gt;thinks&lt;/em&gt; the pilot is intending to do, and then autonomously operates the control surfaces to achieve the effect.  This means that Gen 4 aircraft rely heavily on both computer integrity (and there are plenty of self-healing backups), and the power required to run those systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Power Failure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was a catastrophic total electrical failure and the only remaining power supply was the battery, the only option is for the pilot to restart a generator.  In the event that the engines were operating and all power generation was destroyed, the aircraft would only be flyable for the duration which the battery could provide power to the aircraft--that's a very limited duration.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possible other scenarios could include a dual-engine failure. In this instance, the aircraft may be able to fly fast enough to generate enough airflow down the turbine to turn the generator and perform an airstart, but this would only be useful in a dual engine failure, and only if there was enough altitude and airspeed to trade to make it a realistic option.  Otherwise, the battery would probably be used to power the APU, and attempt a relight.  Again, if both engines relit and the generators (including the APU) failed to produce power, then the aircraft would not be flyable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;But what about the RAT?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although currently in limited use on some trainer aircraft like the T-45, modern fighter aircraft do not use a RAT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So what usually happens in a total electrical failure?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircrew cannot get a generator back online then they eject.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-15T03:55:33.760" LastActivityDate="2014-11-15T03:55:33.760" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9706" PostTypeId="1" AcceptedAnswerId="9710" CreationDate="2014-11-15T11:22:27.910" Score="15" ViewCount="673" Body="&lt;p&gt;What are these triangles and ribbons on this MD83's wing, and what do they do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jwfLr.jpg&quot; alt=&quot;View from cabin of wing with ribbons and triangles pointed out&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4267" LastEditorUserId="1696" LastEditDate="2015-06-04T18:24:17.373" LastActivityDate="2015-06-04T18:25:48.873" Title="What are these ribbons on the wing of an MD-83?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9707" PostTypeId="1" AcceptedAnswerId="9708" CreationDate="2014-11-15T14:39:12.260" Score="18" ViewCount="4336" Body="&lt;p&gt;Is there any airplane model that has a small lavatory-like cabin just for smoking? I have never seen any such planes and that made me wonder why this is?&lt;/p&gt;&#xA;&lt;p&gt;It would not take much more room than a normal lavatory, make it much less likely that someone will smoke in the lavatory regardless of the ban and provide smokers a way to satisfy their need.&lt;/p&gt;&#xA;&lt;p&gt;I will have to add that I am not a smoker, just a person with weird ideas/questions.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Related Questions:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;• &lt;a href=&quot;https://travel.stackexchange.com/questions/5224/are-there-any-airlines-that-still-allow-smoking-on-board-flights&quot;&gt;Are there any airlines that still allow smoking on-board flights&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;• &lt;a href=&quot;https://aviation.stackexchange.com/questions/13116/was-smoking-banned-because-of-passenger-safety-or-occupational-safety&quot;&gt;Was smoking banned because of passenger safety or occupational safety?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4270" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-09-18T05:40:58.537" Title="Why don't airplanes have smoking cabins?" Tags="&lt;aircraft-design&gt;&lt;passenger&gt;&lt;jet&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9708" PostTypeId="2" ParentId="9707" CreationDate="2014-11-15T16:30:42.263" Score="33" Body="&lt;p&gt;Just off the top of my head,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It would take up space that could be used for three or four paying passengers. This would result in increased ticket prices for everybody and the non-smoking majority have no incentive to subsidise a smoking cubicle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It would require a ventilation system that would prevent smoky air from getting into the rest of the cabin, which would add weight and complexity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's a fire risk and a small fire from some idiot disposing of paper in the ashtray could spread; it would be hard to detect such a fire early because you couldn't just put a smoke detector in the smoking cubicle.  (I guess an infra-red detector would work.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Almost nobody tries to smoke in the lavatory so reducing the occurrence of an event that hardly ever happens isn't worth much.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rates of smoking are decreasing in most Western countries, so demand for such a cubicle is already falling.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Anti-smoking legislation is often aimed at worker protection: who's going to clean the smoking cubicle and what equipment will they need?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I doubt there's significant pressure, even from smokers, for such a service to be provided.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2014-11-16T00:51:11.777" LastActivityDate="2014-11-16T00:51:11.777" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9709" PostTypeId="2" ParentId="9626" CreationDate="2014-11-15T16:41:45.650" Score="5" Body="&lt;p&gt;I've no idea how accurate it is but this &lt;a href=&quot;http://boards.straightdope.com/sdmb/showthread.php?t=705576&quot; rel=&quot;noreferrer&quot;&gt;Straight Dope thread&lt;/a&gt; contains confident assertions (some from people who claimed to have worked on these planes) of the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cargo hold inaccessible.&lt;/strong&gt; BAe146, DC-9-30.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Forward cargo holds accessible.&lt;/strong&gt; 737, 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;All cargo holds accessible.&lt;/strong&gt; 777.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, on larger planes, a lot of the luggage will presumably be in containers so getting into the cargo hold isn't necessarily useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;This was originally posted as a comment in the hope that somebody would post something more authoritative as an answer.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-11-15T16:41:45.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9710" PostTypeId="2" ParentId="9706" CreationDate="2014-11-15T16:59:28.050" Score="18" Body="&lt;p&gt;These are &lt;strong&gt;Ice Detection Tufts&lt;/strong&gt; that check for ice. If they are stuck, it indicates there's a layer of ice on the wing, disturbing airflow and presenting a danger for the engines when it detaches. They are focused around the rear root side since this is most likely to be the spot with the most buildup, as remaining cold fuel below flows to this corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SAS had an incident with ice a few years ago in the &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=3&amp;amp;LLID=29&amp;amp;LLTypeID=2&quot;&gt;Gottröra Accident&lt;/a&gt; (SAS Flight 751) that thankfully ended relatively well. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2014-11-15T17:04:54.790" LastActivityDate="2014-11-15T17:04:54.790" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9711" PostTypeId="2" ParentId="9704" CreationDate="2014-11-15T17:16:41.493" Score="10" Body="&lt;p&gt;The article you linked in your question mentions one incident - loss of separation - that's described in more detail &lt;a href=&quot;http://www.iasa.com.au/folders/Safety_Issues/RiskManagement/near_collision.html&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/&quot;&gt;The Aviation Herald&lt;/a&gt; is a good source of information on incidents and accidents but it has very few reports related to holding. There are several about low-fuel incidents because aircraft had to remain in the hold for a long time (&lt;a href=&quot;http://en.wikipedia.org/wiki/Avianca_Flight_52&quot;&gt;Avianca 52&lt;/a&gt; is a well-known case), but I could only find &lt;a href=&quot;http://avherald.com/h?article=46ac29f6&amp;amp;opt=0&quot;&gt;one&lt;/a&gt; that involved a holding pattern more directly and that was also a loss of separation resolved via a &lt;a href=&quot;http://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot;&gt;TCAS&lt;/a&gt; advisory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401&quot;&gt;Eastern Airlines 401&lt;/a&gt; crashed while in a hold, but it was an ad hoc holding pattern and not in a stack with other aircraft. &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Eagle_Flight_4184&quot;&gt;American Eagle 4184&lt;/a&gt; crashed due to icing accumulation while holding but again there were no other aircraft involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could only find one example of an actual collision in a holding pattern which was &lt;a href=&quot;http://en.wikipedia.org/wiki/1960_New_York_mid-air_collision&quot;&gt;over New York in 1960&lt;/a&gt; and in that case only one of the aircraft was holding (inaccurately).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-15T17:16:41.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9712" PostTypeId="2" ParentId="9702" CreationDate="2014-11-15T21:27:25.783" Score="1" Body="&lt;p&gt;Sweep is normally given as the quarter-chord sweep. If not, it must be made clear by some qualifier, like leading-edge sweep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your previous questions let me suspect that you are into a special version of ground-effect vehicles, the Lippisch aerofoil. The picture below shows the X-114.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aF4Nw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing is a delta with negative sweep, so it has a straight leading edge and a forward-swept trailing edge. The idea is to have a positive angle of attack and very little space between the trailing edge and the ground for maximum ground effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a wing has a negative sweep angle. If you take the weighed average of leading ($\varphi_{le}$) and trailing edge sweep angle ($\varphi_{te}$), you get the quarter chord sweep angle ($\varphi_{25}$): $$\varphi_{25} = \frac{\varphi_{te} + 3\cdot\varphi_{le}}{4}$$&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-17T23:51:51.333" LastActivityDate="2014-11-17T23:51:51.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9713" PostTypeId="2" ParentId="9707" CreationDate="2014-11-16T01:59:31.277" Score="5" Body="&lt;p&gt;It's against FAA regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Inflight_smoking&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia says so&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to FAA regulations, smoking lit cigarettes or anything else that produces smoke or flame is prohibited onboard most commercial aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia article doesn't reference the FAA regulation and I haven't found it using Google (I only found &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/3900.47.pdf&quot; rel=&quot;noreferrer&quot;&gt;a document relating to smoking in FAA-controlled buildings&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bloomberg.com/news/2010-04-09/in-flight-smokes-entice-hundreds-to-break-law-20-years-following-u-s-ban.html&quot; rel=&quot;noreferrer&quot;&gt;This 2010 Bloomberg article&lt;/a&gt; references nearly 700 law cases brought &quot;by the FAA&quot; (which might corroborate the claim in the Wikipedia article):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Federal Aviation Administration has brought 696 cases, some for civil fines of thousands of dollars, against people caught smoking aboard airliners in the last five years, said Diane Spitaliere, an agency spokeswoman. Lighting a cigarette on a plane has been banned for 20 years.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="556" LastActivityDate="2014-11-16T01:59:31.277" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9714" PostTypeId="1" AcceptedAnswerId="9718" CreationDate="2014-11-16T02:51:40.870" Score="21" ViewCount="1704" Body="&lt;p&gt;After a downhill bike ride gone wrong last night.  Around midnight I was climbing up a mountain (to my Jeep) with my bike on my back.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I was climbing I was thinking about the fact my headlight had an SOS function (I didn't consider using it).  SOS functions of lights are great and all, but then I realized that as a pilot, myself, I am not sure how to report a person in distress on the surface.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a climber and ROTC cadet, I am well versed in the hand signals, and various ways to flag down airplanes, but as a pilot, if I were to come across someone flashing SOS at night, or flagging me down with a mirror in the day, how would I report their location to get a search and rescue team dispatched? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="97" LastEditDate="2014-11-16T04:31:18.553" LastActivityDate="2015-04-07T23:29:28.990" Title="How does a pilot report a person (on the surface) in distress?" Tags="&lt;safety&gt;&lt;search-and-rescue&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9715" PostTypeId="2" ParentId="7689" CreationDate="2014-11-16T03:14:18.513" Score="7" Body="&lt;p&gt;Jet aircraft (especially large transports) are often equipped with thrust reversers. Not a requirement for landing, but takes some of the load and wear off the wheel brakes and tires. They have them because of the high landing speeds and large masses they have to bring to a stop in a limited amount of space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller aircraft don't fly as fast, so landing speeds are not as high; for the most part, braking requirements are easily met with wheel brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if reverse thrust was beneficial, reversing the engine's rotation would be totally infeasible; engines are simply not designed to run either way round, and any system which would decouple the engine from the propeller (as would be needed if you wanted to implement a &quot;reverse gear&quot;) would be a safety/reliability nightmare, not to mention heavy and expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines are a significant part of the total weight and cost of an airplane. Carrying around an extra just for reverse thrust would be impractical for cost/weight reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many propeller-driven aircraft are equipped with variable-pitch propellers, including many light aircraft; in theory, any of them could have a &quot;reverse&quot; setting, but (as described in one of the other answers) you would only see it on larger aircraft designed for operation on short runways.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2014-11-16T03:14:18.513" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9717" PostTypeId="2" ParentId="9714" CreationDate="2014-11-16T06:08:43.983" Score="6" Body="&lt;p&gt;FWIW, I was specifically taught to use &quot;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow&quot;&gt;pan-pan&lt;/a&gt;&quot; for a scenario like that, at least to get the controllers' attention; anything more depends on the specific situation. My instructor said that pan-pan is always a good way to relay distress calls or other urgent conditions that don't affect your aircraft directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never seen any formal document to support that, but emergencies are thankfully rare and formalities are secondary to getting help to whoever needs it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-07T23:29:28.990" LastActivityDate="2015-04-07T23:29:28.990" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9718" PostTypeId="2" ParentId="9714" CreationDate="2014-11-16T06:51:56.523" Score="20" Body="&lt;p&gt;I would treat an active SOS signal from the ground the same way I would treat an ELT signal on 121.5: Contact ATC (or Flight Service if you're not sure what ATC frequency to use) and inform them of the event.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with reporting an ELT you should be prepared to tell ATC:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What kind of signal you've observed&lt;br&gt;&#xA;(ELT, signal light, signal mirror, &quot;SOS&quot; or &quot;HELP&quot; spelled out with rocks…)&lt;/li&gt;&#xA;&lt;li&gt;The time you observed the signal&lt;br&gt;&#xA;(Ideally you'll report it while overhead &amp;amp; actively monitoring it)&lt;/li&gt;&#xA;&lt;li&gt;Your location and altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Ideally you'll be able to give your location as a GPS fix &lt;a href=&quot;https://aviation.stackexchange.com/a/9716&quot;&gt;as SHAF described&lt;/a&gt;.&lt;br&gt;&#xA;If that's not possible there are other options, in roughly-descending order of accuracy:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A DME fix (radial &amp;amp; DME distance)&lt;/li&gt;&#xA;&lt;li&gt;A VOR fix (the intersection of two radials from separate stations)&lt;/li&gt;&#xA;&lt;li&gt;A VOR radial &amp;amp; visual landmark (ideally something on the sectional chart)&lt;br&gt;&#xA;While just a radial is not very useful it can be helpful in conjunction with a landmark: &quot;South side of Mt. Greylock, on the 350 radial off Chester VOR&quot; helps narrow down the search area considerably.&lt;/li&gt;&#xA;&lt;li&gt;A visual landmark based on the sectional chart.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;ATC may also ask you to circle the distress signal and ident in order to get a radar fix to supplement any of the above.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-11-16T06:51:56.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9719" PostTypeId="1" CreationDate="2014-11-16T08:15:01.177" Score="4" ViewCount="20477" Body="&lt;p&gt;I am looking to purchase an aircraft, and I've found one described as follows&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Total time is 6300 hours  &lt;/li&gt;&#xA;  &lt;li&gt;Engine time since major overhaul 2100 hours&lt;br&gt;&#xA;  Engine runs strong and compression is all in the 70s&lt;/li&gt;&#xA;  &lt;li&gt;Has VAL Avionics all-in-one VOR/LOC/GS unit&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The owner also states that the engine was rebuilt 556 hours ago, but this was never entered in the log books, so we're working based on 2100 hours since overhaul.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have done a pre-buy inspection through A&amp;amp;P mechanic. On the report was mentioned, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TACH TIME ;8131.18&lt;br&gt;&#xA;  HOBBS ;  7141.9&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Can you explain for me what these time figures mean and how I can judge the remaining life left for this engine and airframe?&lt;/p&gt;&#xA;" OwnerUserId="4277" LastEditorUserId="64" LastEditDate="2015-01-09T22:55:21.187" LastActivityDate="2015-01-09T23:36:37.410" Title="How do you determine how much &quot;life&quot; an aircraft has left?" Tags="&lt;aircraft-purchase&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9722" PostTypeId="1" AcceptedAnswerId="9728" CreationDate="2014-11-16T11:03:47.973" Score="41" ViewCount="35590" Body="&lt;p&gt;On a clear night, everyone can spot planes quite easily: they have flashing lights. I have noticed that the pattern seems different for different planes, and tried to find a meaning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I saw so far is that they seem to have three lights that flash, two at the wings, one at the tail. Those at the wings flash two times (approximately per second, in quick succession), and that one at the tail flashes only once, along with the first flash of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that explains two patterns I seem to see from further away: Two flashes and one flash. It is probably that I am just not seeing the wings flashing for those where I only see one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far so good, but then again sometimes I see planes with more flashing, and those are faster. I had difficulties to count them, but it's at least three, maybe four quick flashes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Do these different patterns have any meaning?&lt;/em&gt; I tried to match up the planes with the flight radar information, but since it is quite crowded around here, I wasn't really able to identify them. But whenever I saw that quick flashing ones, there was a military plane around, is that just coincidence?&lt;/p&gt;&#xA;" OwnerUserId="2108" LastEditorUserId="1696" LastEditDate="2015-04-29T14:29:41.167" LastActivityDate="2020-03-16T20:10:52.303" Title="Do lights on aircraft flash in a specific pattern?" Tags="&lt;safety&gt;&lt;regulations&gt;&lt;aircraft-lighting&gt;" AnswerCount="7" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9723" PostTypeId="2" ParentId="9722" CreationDate="2014-11-16T11:27:59.997" Score="8" Body="&lt;p&gt;No, the pattern has no meaning, though the double-flash does identify the plane as an Airbus; other manufacturers use a single flash.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-11-16T11:27:59.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9724" PostTypeId="1" AcceptedAnswerId="9732" CreationDate="2014-11-16T14:36:21.853" Score="8" ViewCount="2689" Body="&lt;p&gt;There are many awesome pictures of this phenomenon such as this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/m60Vm.jpg&quot; alt=&quot;F-18 with condensation cone&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the physical explanation of how this occurs? Does it occur only when the airplane crosses the sound barrier or does it continue throughout the whole supersonic regime if enough water vapour is present in the atmosphere? What factors does this condensation depend on?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="1696" LastEditDate="2015-01-25T17:03:10.627" LastActivityDate="2015-01-25T17:03:10.627" Title="How are condensation cones created by supersonic airplanes?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9725" PostTypeId="2" ParentId="9682" CreationDate="2014-11-16T15:11:53.983" Score="3" Body="&lt;p&gt;I found &lt;a href=&quot;http://perso.univ-rennes1.fr/laurent.blanchard/Profils/&quot; rel=&quot;nofollow noreferrer&quot;&gt;a web site&lt;/a&gt; (mostly in French, but data are language agnostic!). Calculation were made with &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;nofollow noreferrer&quot;&gt;XFOIL&lt;/a&gt;. This is typically what can be found there (with data text file).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ELxuJ.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/AMXGk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/8QabY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1655" LastActivityDate="2014-11-16T15:11:53.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9726" PostTypeId="1" CreationDate="2014-11-16T15:43:59.853" Score="4" ViewCount="2547" Body="&lt;p&gt;How are commercial aircraft insulated and what kind of fire barrier material is being used?  How much insulation is required in a typical Boeing 747 vs. a Boeing 787?&lt;/p&gt;&#xA;" OwnerUserId="4280" LastEditorUserId="19" LastEditDate="2015-02-18T19:50:20.083" LastActivityDate="2015-02-18T19:50:20.083" Title="What kind of insulation is used on commercial aircraft?" Tags="&lt;aircraft-design&gt;&lt;boeing&gt;&lt;fire&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9728" PostTypeId="2" ParentId="9722" CreationDate="2014-11-16T16:55:11.960" Score="38" Body="&lt;p&gt;Civilian aircraft have flashing lights based on manufacturer design preference.  As others have stated, aircraft like Boeing and Airbus have different patterns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, military aircraft can often select the pattern they want to use.  This helps military pilots identify key tactical aircraft during night operations, such as the tanker flying around the carrier.  It is definitely not coincidental that you noticed military aircraft with a unique pattern, although I'm truly shocked at your attention to detail.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-16T17:32:54.903" LastActivityDate="2014-11-16T17:32:54.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9729" PostTypeId="2" ParentId="9719" CreationDate="2014-11-16T20:01:20.947" Score="10" Body="&lt;p&gt;I'm going out a bit on a limb here, and it isn't specifically an answer to exactly what you are asking (which is what Stack Exchange tends to strive for), but I think this is the answer you &lt;em&gt;need,&lt;/em&gt; so at the risk of receiving a couple of downvotes, here goes.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;engine was rebuilt 556 hours ago but was a problem because &lt;strong&gt;was never entered in the log books&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think that boldfaced text &lt;strong&gt;makes your entire question moot.&lt;/strong&gt; In other words, the answer to your specific question doesn't really make any difference; the above tells you all you really need to know. &lt;em&gt;Which is:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/595/simon&quot;&gt;Simon&lt;/a&gt; said in a comment, if the seller readily admits to not entering an &lt;em&gt;engine rebuild&lt;/em&gt; into the log, then &lt;em&gt;what else has not been entered into the log?&lt;/em&gt; Especially if you are a beginner, that's the sort of thing I would expect will come back to bite you hard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total time is stated as 6300, Hobbs time is stated as 7142, tach time is stated as 8131. And that's by the seller (including the mechanic's report provided by the seller). Does the difference between these figures inspire confidence in the airplane's state, the seller's honesty, and &lt;em&gt;your ability to get an accurate picture of what you are buying?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has been stated, &lt;em&gt;the only person qualified to answer your question about the state of the engine in a reasonably objective manner is the mechanic who inspected the engine.&lt;/em&gt; The odds that this &lt;em&gt;particular&lt;/em&gt; mechanic will stumble across this question is already quite low. What are the odds that the mechanic will not only stumble across the question, but also recognize the particular aircraft you are asking about and decide to answer the question with anything that is not already in the inspection report (which you already have received from the seller)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;More generally, with well-serviced aircraft,&lt;/strong&gt; it isn't as easy as just saying &quot;this aircraft has X number of hours of service left&quot; even based on the current state of a single piece such as the (an) engine, because with good servicing it's perfectly possible to extend the service life of an aircraft for a very long time. A well-treated aircraft is a very different beast compared to perhaps a car (which might be lucky to get a checkup once a year and an oil change every few thousand miles), of course in part because the failure mode is much more serious. (If your car fails on the highway you pull over and call a tow truck; if an airplane fails in mid-flight then what do you do?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally and for the specific situation you describe, I wouldn't go near that particular aircraft if I can avoid it, let alone buy it. At the very least buy something where the &lt;em&gt;trivially&lt;/em&gt; obtainable numbers match.&lt;/p&gt;&#xA;" OwnerUserId="753" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-11-17T08:09:21.443" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9730" PostTypeId="2" ParentId="9707" CreationDate="2014-11-16T20:04:08.597" Score="0" Body="&lt;p&gt;During 60's to 70's smoking was not prohibited. However, every rule and prohibition depends on safety, prohibition of smoking on aircrafts also commits to safety of flight. Smoking is a big crime on planes, if there are couple of attempts to smoke on a flight that`s considered as terrorist act, at that point whoever tries to smoke are accused as terrorist. Pilots land aircraft to closest airport and police takes suspects from aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possibility of fire is main reason for this rule. Seats or floor could catch fire from cigarettes. Even if you smoke lavatory, it is a lot more dangerous because there are lots of paper towels and etc. that catches fire in lavatories.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if some special cabins has been built, there are still risk of fire because of inattention or terrorist could try to burn down the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could say that if somebody tries to burn down an airplane they could use lavatory to that. Because of this aircraft lavatories are equipped with smoke detectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essential of aviation rules to ban everything that could not be controlled up in the air.&lt;/p&gt;&#xA;" OwnerUserId="2190" LastEditorUserId="64" LastEditDate="2014-11-17T17:37:52.320" LastActivityDate="2014-11-17T17:37:52.320" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9731" PostTypeId="2" ParentId="9722" CreationDate="2014-11-16T20:18:10.553" Score="6" Body="&lt;p&gt;Red flashing lights top and bottom of the aircraft are turned on when pilots are clear to start engine. If you see those lights you know that there is an aircraft with running engines. So it could be moving towards to you, so be careful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail light is for it to be seen from behind. The aircraft behind of you knows there is an aircraft in front of him.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flashing light at wings means that this aircraft is airborned or about to be. &#xA;Pilots turns that lights on when they are on the runway. These lights are stays put during the entire flight until the aircraft off the runway after landing. &lt;/p&gt;&#xA;" OwnerUserId="2190" LastEditorUserId="2190" LastEditDate="2014-11-18T19:59:41.727" LastActivityDate="2014-11-18T19:59:41.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9732" PostTypeId="2" ParentId="9724" CreationDate="2014-11-16T20:25:06.627" Score="11" Body="&lt;p&gt;It is important to note that the vehicle is not traveling at supersonic speed when condensation collars (rockets) or condensation cones (aircraft) occur. It is merely close to the speed of sound.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;From the vehicle's viewpoint&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Air is accelerated by the displacement effect of the vehicle - it pushes the air aside and around itself, causing the flow to accelerate and to become supersonic relative to the vehicle. This acceleration is directly connected with lower pressure (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;this answer&lt;/a&gt; for a detailed explanation), and air with high relative humidity will be pushed beyond its &lt;a href=&quot;https://en.wikipedia.org/wiki/Dew_point&quot; rel=&quot;nofollow noreferrer&quot;&gt;dew point&lt;/a&gt;, causing the water vapor to condensate. Please note that the onset of condensation is slightly delayed, so the fog is not strictly indicating the region of lowest pressure. Also, the forward cone is not the same as the forward shock front of a &lt;a href=&quot;http://www.lmfa.ec-lyon.fr/ISAIF/Data/Invited_lectures/IL142/IL142.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;lambda shock&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the rear boundary of the condensation is indeed caused by a shockwave. The low pressure area is instantly ended by a compression shock, when the supersonic flow around the aircraft is abruptly decelerated to subsonic speed by a compression shock. This raises the local air pressure back to around ambient pressure, so the capacity to absorb water is raised again and the fog evaporates. Again, this happens with a slight delay, so the end of the condensation area does not coincide with the compression shock but follows it.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;From the viewpoint of the air&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Since the low pressure area is caused by the aircraft, it travels with the aircraft, and so does the condensation effect. The air around the aircraft or rocket is accelerated towards the vehicle by its pressure field, which causes the condensation. Now the air is so fast relative to the vehicle that it is decelerated and recompressed by a straight shock, causing the condensation to disappear again.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Factors&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A relatively blunt vehicle traveling at close to Mach 1 and humid, almost saturated air are the factors which help this effect to occur. Note that you can witness similar condensation effects over the wings of airliners in humid air during the landing phase, when flaps are fully deployed. Here, however, the condensation does not end abruptly, since no shock is involved. Also, the disturbances produced by the aircraft do not reach out so far at lower speed, so the condensation happens only close to the aircraft's surface. Bluntness helps: The cockpit causes its own small condensation area shortly past its maximum thickness, where suction due to displacement is highest.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-11-16T22:17:57.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9733" PostTypeId="2" ParentId="9722" CreationDate="2014-11-16T22:38:52.437" Score="6" Body="&lt;p&gt;In general, lights flash for the same reason that hazard lights on a car flash; because flashing lights are easier to see than solid lights. This applies to a lot of things in aviation. Building lights, tower lights, aircraft lights all flash because it is easier to see a strobe in low visibility than a steady light. White strobes are also brighter and red strobes are less reactive to the eye (which is why cockpits use red light). All of these combined help to make strobes easier to see and identify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the pattern, as many have mentioned there is no specification on a specific pattern that aircraft manufacturers need to follow. For an aircraft like an airbus, wing tips may have a different blink pattern because the manufacturer wanted it that way. If I could take a guess, it would be so you can identify the orientation of the aircraft if you cannot still see the solid colored lights.&lt;/p&gt;&#xA;" OwnerUserId="4286" LastActivityDate="2014-11-16T22:38:52.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9734" PostTypeId="2" ParentId="9726" CreationDate="2014-11-17T02:57:20.600" Score="3" Body="&lt;p&gt;This &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q4/4/&quot; rel=&quot;nofollow&quot;&gt;article&lt;/a&gt; from Boeing describes fire safety on their planes, and they mention &quot;fire-protective insulation blankets.&quot; A quick google search suggests that in non-aviation contexts, these are usually ceramic fiber. So it seems likely that at least one form of fire insulation in modern transport-class aircraft is ceramic fiber fire blankets.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2014-11-17T02:57:20.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9735" PostTypeId="1" AcceptedAnswerId="9738" CreationDate="2014-11-17T09:47:26.320" Score="19" ViewCount="3258" Body="&lt;p&gt;Watching this &lt;a href=&quot;https://www.youtube.com/watch?v=8W0KcQLImuo&quot; rel=&quot;nofollow noreferrer&quot;&gt;Video of a L-1011&lt;/a&gt;, I noticed an orange/brown object on the back of the jet-engine pylons I never saw before. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is it?&lt;/li&gt;&#xA;&lt;li&gt;What's the purpose of it?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BlzbP.png&quot; alt=&quot;L-1011 Jet Engine pylons&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="22726" LastEditDate="2018-12-30T23:28:48.790" LastActivityDate="2018-12-30T23:28:48.790" Title="Orange object on back of jet-engine pylons, what is it?" Tags="&lt;aircraft-design&gt;&lt;lockheed-tristar&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9736" PostTypeId="2" ParentId="3300" CreationDate="2014-11-17T11:01:27.337" Score="0" Body="&lt;p&gt;I think that both single rotor than quadcopters will cohesist, at least for some time. The reason for creating manned quadcopters are countless. A quadcopter could be driven like a car, while real helicopters need hundreds of flight hours for a pilot to master. this will lead to mainstream production and lower manufacturing prices to make them available to the mass.&#xA;about usefullness: a quad copter can have the blades ENCLOSED inside protecting structures, making their flight viable for cramped areas, where trees, buildings and poles would otherwise destroy normal helicopters. this makes a quadcopter much a better choice for rescue operations.&#xA;probably normal helicopters will stay a better choice for long range operations and speed.&lt;/p&gt;&#xA;" OwnerUserId="4292" LastActivityDate="2014-11-17T11:01:27.337" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9737" PostTypeId="2" ParentId="9735" CreationDate="2014-11-17T12:06:56.667" Score="7" Body="&lt;p&gt;I think this is an infrared counter-measure device, i.e. a device intended to protect aircraft from &quot;heat seeking&quot; missiles. Saudi no doubt flies to some potentially dangerous spots in the Middle East.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Infrared_countermeasure&quot; rel=&quot;nofollow&quot;&gt;See this article.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4294" LastEditorUserId="65" LastEditDate="2014-11-17T19:07:16.097" LastActivityDate="2014-11-17T19:07:16.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9738" PostTypeId="2" ParentId="9735" CreationDate="2014-11-17T12:10:18.580" Score="20" Body="&lt;p&gt;Manu H is right. It is an IR jammer device. &lt;a href=&quot;http://www.airliners.net/photo/Saudi-Arabian-Royal/Boeing-747SP-68/1308171/L/&quot; rel=&quot;nofollow&quot;&gt;Saudi (corrected from the comment of David Richerby:)&lt;strong&gt;Royal Flight&lt;/strong&gt; airliners tend to have them (root of the wing, next to the light)...&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="2122" LastEditDate="2014-11-18T11:07:12.457" LastActivityDate="2014-11-18T11:07:12.457" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9739" PostTypeId="1" CreationDate="2014-11-17T13:17:55.593" Score="2" ViewCount="231" Body="&lt;p&gt;It is known that aircraft flying in Europe above FL285 &lt;a href=&quot;https://www.eurocontrol.int/articles/data-link-services-dls-mandate&quot; rel=&quot;nofollow&quot;&gt;will be mandated to be capable of PM-CPDLC data link communication&lt;/a&gt;. Our 767-300 has ACARS CMU, Pegasus FMC, MCDU and VHF radios (three). The ACARS system works fine, but there is no SATCOM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As indicated on COMMISSION REGULATION (EC) No 29/2009, aircraft with an individual airworthiness certificate issued before 1 January 2014 that are equipped with Future Air Navigation System (FANS-1) are exempt from the requirement of the PM-CPDLC for the lifetime of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, would our 767-300 aircraft with the above avionics be considered FANS-1 capable and qualify for the exemption? Any suggestions on how I can confirm that? &lt;/p&gt;&#xA;" OwnerUserId="1676" LastEditorUserId="62" LastEditDate="2014-11-17T15:47:42.717" LastActivityDate="2014-11-18T01:51:11.933" Title="Would a 767-300 be considered FANS-1 capable without SATCOM?" Tags="&lt;avionics&gt;&lt;easa&gt;&lt;cpdlc&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9740" PostTypeId="1" CreationDate="2014-11-17T13:47:02.620" Score="7" ViewCount="2720" Body="&lt;p&gt;Setting aside the likely legal factors for a moment, what are the limiting factors when flying a model plane to high altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I see it these could be:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Battery power consumption - Model planes seem to have a battery life of less than an hour. There is a large distance to be covered in a climb ~20KM.&lt;/li&gt;&#xA;&lt;li&gt;External forces - Strong winds/turbulence acting on a relatively small and light airframe could easily blow the plane off course. I'm not sure how severe these would be at higher altitude.&lt;/li&gt;&#xA;&lt;li&gt;Air pressure/oxygen content - I presume this could reduce flying efficiency.&lt;/li&gt;&#xA;&lt;li&gt;Low air temperatures affecting the operation of the electronics inside and perhaps the control surfaces.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4296" LastActivityDate="2016-02-08T02:15:12.533" Title="What are the limiting factors when flying a model UAV plane to high altitude?" Tags="&lt;altitude&gt;&lt;rc-aircraft&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9741" PostTypeId="1" AcceptedAnswerId="9743" CreationDate="2014-11-17T13:53:15.577" Score="6" ViewCount="278" Body="&lt;p&gt;I am not a pilot, my understanding about flight is limited. &#xA;EASA CPDLC will require airplanes to be capable of PM-CPDLC data communication to fly above FL285. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an airline with multiple 767-300 and 757-200 airplanes, would it be feasible to consider the option of flying &lt;em&gt;below&lt;/em&gt; FL285 in European airspace, instead of ceasing operation in the region or investing millions of dollars for avionics upgrades? &lt;/p&gt;&#xA;" OwnerUserId="1676" LastEditorUserId="62" LastEditDate="2014-11-17T15:44:22.400" LastActivityDate="2014-11-17T22:30:22.847" Title="Would flying below FL285 be feasible for aircraft that don't comply with EASA CPDLC?" Tags="&lt;aircraft-performance&gt;&lt;easa-regulations&gt;&lt;easa&gt;&lt;cpdlc&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9743" PostTypeId="2" ParentId="9741" CreationDate="2014-11-17T14:27:21.930" Score="8" Body="&lt;p&gt;Unlikely. The extra fuel burned would cost a lot more than the required Avionics upgrade. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the 75/767 would be well below optimum cruise level.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-11-17T14:27:21.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9744" PostTypeId="2" ParentId="9740" CreationDate="2014-11-17T14:52:27.387" Score="4" Body="&lt;p&gt;The same rules apply as for &quot;real&quot; airplanes, and the topic has been covered well in previous questions. With model airplanes, scaling laws make the task easier, rsp. the possible maximum altitude higher. I would suggest to hang the plane below a balloon to get it up without draining batteries. NASA has &lt;a href=&quot;http://science.nasa.gov/science-news/science-at-nasa/2003/02may_bigblue/&quot; rel=&quot;nofollow noreferrer&quot;&gt;done it before&lt;/a&gt; with a remotely controlled glider.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the limiting factors please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/9188/what-defines-the-maximum-altitude-a-plane-can-reach&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7691/how-high-can-propeller-airplanes-fly?rq=1&quot;&gt;Here&lt;/a&gt; is a question for the maximum altitude of propeller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology&quot;&gt;Here&lt;/a&gt; is another on the feasibility of geostationary drones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the acceptable fragility of the design, a model aircraft should easily go down to a wing loading of 10 $kg/m^2$ and then be flyable at 36 km of altitude. At a true airspeed of 155 m/s it will fly at half the speed of sound and the Reynolds number on the wing with an assumed chord of 0.25 m will be below 20,000. You need to fly it with a lift coefficient of 1.1, which will be a challenge at the low Reynolds number, and the L/D will probably be less than 10, so your propulsion needs to be quite powerful to hold the altitude up there. I haven't done the numbers, but the propeller will be huge. With back-of-the-envelope calculations, my answer for the maximum altitude is 36 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence should be of no concern - all flow patterns up there are of extremely large scale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The low temperature should also be tolerable if all systems are electric. It is not so cold up there: The standard atmosphere gives -34°C.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-11-18T09:57:54.133" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9745" PostTypeId="1" AcceptedAnswerId="9747" CreationDate="2014-11-17T16:01:02.413" Score="8" ViewCount="3419" Body="&lt;p&gt;I was watching &lt;a href=&quot;https://www.youtube.com/watch?v=KDgvWa-EbbE&quot; rel=&quot;nofollow&quot;&gt;this video of a FedEx MD-10&lt;/a&gt; landing and some questions came up, of course again the unprofessional YouTube comments didn't help.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How many miles before the runway should an airliner put the gear down?&lt;/li&gt;&#xA;&lt;li&gt;Was the aircraft in the video too close?&lt;/li&gt;&#xA;&lt;li&gt;At which distance does &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;nofollow&quot;&gt;radio altimeter&lt;/a&gt; warn the pilots?&lt;/li&gt;&#xA;&lt;li&gt;Is the following YouTube comment accurate?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This was FedEx flight 1356 and I can tell you what happened. During approach there was an anomaly on the left slat and it was being watched. Also during approach engine no.1 was heating up to unacceptable levels and because of all of this the gear wasn't lowered right away. It was only due to TCAS and the alarms on board that it was noticed as the aircraft was approaching it's minimums. Upon landing the crew was reprimanded for not following proper procedure and was suspended with pay.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="1696" LastEditDate="2015-12-14T16:35:08.727" LastActivityDate="2015-12-14T16:35:08.727" Title="How many miles before the runway should an airliner put the gear down?" Tags="&lt;landing&gt;&lt;landing-gear&gt;&lt;pilot-technique&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9746" PostTypeId="2" ParentId="1189" CreationDate="2014-11-17T17:20:18.073" Score="4" Body="&lt;p&gt;My old instructor relayed a story to me this weekend that explains why you should NOT retract the flaps immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot (either student-Commercial or certificated-Commercial, unclear), touched down, and immediately went for the flaps.   Somehow, she grabbed the gear-lever instead, and raised it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mains were firmly down, so they did not retract.&lt;br&gt;&#xA;However, the nose was still high, and it began to retract.&lt;br&gt;&#xA;When the nose dropped a second later, it ended with the plane nosing into the ground, destroying the prop.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-11-17T17:20:18.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9747" PostTypeId="2" ParentId="9745" CreationDate="2014-11-17T17:25:16.407" Score="12" Body="&lt;p&gt;To answer the last part of your question, as ratchet freak said, the TCAS doesn't warn the pilot when he should deploy landing gear. However, &lt;a href=&quot;http://www.skybrary.aero/index.php/Terrain_Avoidance_and_Warning_System_%28TAWS%29&quot;&gt;the ground proximity warning system/terrain avoidance and warning system (GPWS/TAWS)&lt;/a&gt; does. &lt;a href=&quot;http://www.boeing-727.com/Data/systems/infogpws.html#MODE4&quot;&gt;GPWS Mode 4A&lt;/a&gt; is &quot;Unsafe Terrain Clearance With Landing Gear Not Down&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane is less than 700ft (based on the radio altimeter's measure) high and under mach .35, there is an aural alert in the cockpit saying &quot;Too low - gear&quot;. The message is repeated until the situation is corrected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the warning is based on the height and speed of the aircraft. Not on its distance to the airport.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-11-17T17:25:16.407" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9748" PostTypeId="2" ParentId="9745" CreationDate="2014-11-17T17:26:48.480" Score="2" Body="&lt;p&gt;As people have said I the comments there is no general rule as to when to lower the gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All major airlines have Standard Operating Procedures. As part of the Normal Procedures Section there will be profiles for the different types of approaches (ILS, GNSS, VOR etc..). It's normal as part of these to show the recommended config of the aircraft at a particular stage of the approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example would be to lower the gear when capturing the Glide Path as part of an ILS approach. This aids speed control and ensures the aircraft is stable at the required minima.&lt;/p&gt;&#xA;" OwnerUserId="412" LastActivityDate="2014-11-17T17:26:48.480" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9749" PostTypeId="2" ParentId="9703" CreationDate="2014-11-17T22:05:45.987" Score="1" Body="&lt;p&gt;There is no set time because there are too many factors. On a large airfield it could take more than 5 minutes just to taxi to the runway. If you maintain a plane on alert (expensive and time consuming), you could get it rolling inside of 5 minutes. That means:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The pilot is fully ready and has all his stuff ready to go; literally waiting to jump into the plane&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft has been pre-flighted, fueled and is on the apron ready to go&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Munitions have been loaded and checked&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Needless to say, keeping aircraft in this condition is expensive and I would imagine is only done at certain specific airbases where some special need for a fast launch is required. Loading and unloading weapons is a very time-consuming process and there is a lot of red tape associated with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time constraints have nothing to do with the type of aircraft. It's more a question of the human factor and lots of little things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, another factor is how much you are willing to skip. You might have a 40-point checklist and 25 of them are &quot;optional&quot; items that pertain to safety. If you don't care about dying, feel free to ignore them and you can take off 5 minutes faster.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-11-17T22:05:45.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9750" PostTypeId="2" ParentId="9586" CreationDate="2014-11-17T22:18:17.673" Score="1" Body="&lt;p&gt;There was probably no incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It just means your plane was ready to take off and had to wait longer than expected. Whenever a plane is ready to go the controller has to decide whether he can let it go or should wait for an incoming plane. The controller was probably just playing it safe and decided to make your plane wait, so the pilot got a little exasperated, &quot;Sorry folks, got to wait for another plane to land.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2014-12-03T18:26:54.887" LastActivityDate="2014-12-03T18:26:54.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9751" PostTypeId="2" ParentId="9741" CreationDate="2014-11-17T22:30:22.847" Score="3" Body="&lt;p&gt;The adoption of CPDLC is more or less voluntary, because they have created &quot;exceptions&quot; for practically every single aircraft that does not have it built in. Flying below 28K is not practical except for short flights, but it does not matter because it unlikely they will start banning aircraft that do not have the equipment. Note that there are international treaties in place that mandate countries allow commercial overflight and if you just started banning various aircraft, you would be in violation of those treaties.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-11-17T22:30:22.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9752" PostTypeId="2" ParentId="475" CreationDate="2014-11-17T22:55:59.093" Score="40" Body="&lt;h2&gt;Landing on &quot;The Boat&quot;&lt;/h2&gt;&#xA;&#xA;&lt;h2&gt;Glossary&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Approach turn/ 180: The approach turn itself is a 180 degree turn (190 degrees at the boat because of the angled deck) that is usually broken down into 5 segments: the 180 position, the 135, the 90 (halfway through the turn), the 45 and the groove.  Each respective position indicates the number of degrees left in the turn prior to rolling out in the groove.&lt;/li&gt;&#xA;&lt;li&gt;(The) Ball or Meatball: an orange orb of light emitted from the IFLOLS.  A green horizontal row of lights (known as the datum) indicates proper glide slope.  If the ball is below the datum, the aircraft is low, and if its above the datum, the aircraft is high.  Aircraft should strive to keep the ball on the happy side.&lt;/li&gt;&#xA;&lt;li&gt;Ball Call: &lt;em&gt;Format&lt;/em&gt;: &quot;(Side-number) (aircraft type) ball, (fuel-state), (auto-throttles)&quot; &lt;em&gt;Example&lt;/em&gt;: &quot;123 Rhino ball, 9.0&quot;&lt;/li&gt;&#xA;&lt;li&gt;Carrier Break: A type of left hand overhead performed at 800ft AGL and 350+kts (for hornet guys)&lt;/li&gt;&#xA;&lt;li&gt;BRC: the basic recovery course.  The course at which the ship is currently traveling, which does &lt;em&gt;not&lt;/em&gt; include the offset for the angled deck.&lt;/li&gt;&#xA;&lt;li&gt;Groove: the final portion of the approach (what civilians might call short-final)&lt;/li&gt;&#xA;&lt;li&gt;Initial: on BRC, 3-5nm behind the ship, 800ft AGL, 350+kts, the starting point for the day approach&lt;/li&gt;&#xA;&lt;li&gt;Interval: the specific aircraft in the pattern whose approach will commence just prior to yours, and whose separation you are responsible for not violating.&lt;/li&gt;&#xA;&lt;li&gt;On speed: the proper AoA that will achieve the correct hook angle to catch the target wire of the carrier.  On speed airspeed can be approximated by the aircraft weight, but the term on speed does not refer to airspeed specifically, but units of AoA.&lt;/li&gt;&#xA;&lt;li&gt;Side number: The 3 digit number assigned to the aircraft.  This is not the buno number (military aircraft don't have N numbers), it is a squadron specific identifier.  I will hence refer to '123' as the default side number.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Carrier Procedure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For simplicity's sake we'll pick it up at initial.  Glossary items have been &lt;em&gt;italicized&lt;/em&gt; for ease of reading.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&quot;123 flight of x, &lt;em&gt;initial&lt;/em&gt;&quot;, ATC will then give the required instruction.&lt;/li&gt;&#xA;&lt;li&gt;The flight will then side-step to the right of the carrier island, and begin looking for their &lt;em&gt;interval&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Reaching the carrier, the flight will then perform the &lt;em&gt;carrier break&lt;/em&gt; on their &lt;em&gt;interval&lt;/em&gt;, ensuring that aircraft will arrive in 60 second intervals.&lt;/li&gt;&#xA;&lt;li&gt;Landing checklist: 3 down and locked, flaps full, hook down, antiskid off, dispenser off, &lt;em&gt;on speed&lt;/em&gt; XXX.&lt;/li&gt;&#xA;&lt;li&gt;Once turned downwind, the aircraft will descend from 800ft AGL to 600ft AGL (the carrier pattern is flown at 600ft), and the aircraft will ensure it has proper lateral separation (abeam distance) from the carrier so as not to overshoot or undershoot on the &lt;em&gt;approach turn&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Once abeam the LSO shack (or when the white of the round down is visible), the aircraft will increase VSI to approximately 200-300fpm and begin a 27-30 degree AoB turn.  Proper time in the &lt;em&gt;groove&lt;/em&gt; is limited to only 15-18 seconds.  Too long or too short in the groove and the LSO can wave you off, so it is paramount that the &lt;em&gt;approach turn&lt;/em&gt; be performed at the proper position.&lt;/li&gt;&#xA;&lt;li&gt;At the &lt;em&gt;90&lt;/em&gt;, altitude should be 450ft AGL, and VSI should increase to 500fpm.&lt;/li&gt;&#xA;&lt;li&gt;At the &lt;em&gt;45&lt;/em&gt; the aircraft should be crossing the wake of the carrier, altitude should be 325-375ft AGL, and the &lt;em&gt;ball&lt;/em&gt; should appear to rise. Note: Rolling into the &lt;em&gt;groove&lt;/em&gt;, the &lt;em&gt;ball&lt;/em&gt; should appear either centered or slightly high.&lt;/li&gt;&#xA;&lt;li&gt;Once in the groove, with a visible &lt;em&gt;ball&lt;/em&gt;, the aircraft makes its &lt;em&gt;ball call&lt;/em&gt;.  The LSO will respond with &quot;roger ball&quot;, which is the aircraft's clearance to land.&lt;/li&gt;&#xA;&lt;li&gt;Once established in the groove, the aircraft should be roughly 700fpm and flying the ball for glidepath.  The pilot's scan becomes: &lt;em&gt;meatball&lt;/em&gt;, lineup, AoA, &lt;em&gt;meatball&lt;/em&gt;, lineup, AoA, &lt;em&gt;meatball&lt;/em&gt;, lineup, AoA (you get the point).&lt;/li&gt;&#xA;&lt;li&gt;As the aircraft flies in the &lt;em&gt;groove&lt;/em&gt; the runway will constantly slip to the right requiring small, almost imperceptible, lateral stick inputs (and matching power corrections to account for the loss in lift).  The pilot will strive to keep the aircraft on centerline, &lt;strong&gt;&lt;em&gt;on speed&lt;/em&gt;&lt;/strong&gt;, with a centered &lt;em&gt;ball&lt;/em&gt;.  Note: failure to keep the aircraft &lt;em&gt;on speed&lt;/em&gt; can result in either a bolter, or an in-flight engagement.  It is imperative the aircraft maintain the proper AoA.&lt;/li&gt;&#xA;&lt;li&gt;Just prior to touchdown, as the aircraft passes over the ramp, the pilot's scan will shift to &lt;em&gt;ball, ball, ball, ball, ball&lt;/em&gt;, and the touchdown should come as a surprise.  This is referred to as &quot;flying the &lt;em&gt;ball&lt;/em&gt; all the way to touchdown&quot;.  Pilot's that deck spot (ie, attempt to fly to a specific spot on the deck) often fly down through the glideslope at the last moment and land short.&lt;/li&gt;&#xA;&lt;li&gt;Once on the deck, the throttles will go to full military power (just shy of AB), and when landing has been assured, then the power will be reduced and the aircraft taxied off the landing area.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Shore Procedure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Naval aviation revolves around flying at the boat.  It is imperative that the procedures used at the boat become second nature, that they become ingrained in muscle memory.  To this effect, all shore based VFR approaches will be flown in exactly the same manner as would be at the carrier, with a few minor exceptions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Antiskid will be on&lt;/li&gt;&#xA;&lt;li&gt;The hook (for a non-emergency) will be up&lt;/li&gt;&#xA;&lt;li&gt;Aircraft aren't required to have 60 seconds of separation, we routinely land with aircraft taxiing down the runway.&lt;/li&gt;&#xA;&lt;li&gt;The throttles will be retarded unless executing a touch and go.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Otherwise, naval air stations that house carrier based aircraft all have I/FLOLS installed, and the ball is flown during normal VFR approaches to the field.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Further Reading&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Edit)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following link, provided by the Chief of Naval Air Training Command (CNATRA), is an unclassified, publicly available, training guide used to train potential Naval Aviators to land on the boat for the first time.  The procedures are nearly identical, with a few nuances related to T-45 training operations, to the procedures used daily by fleet aviators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cnatra.navy.mil/shared/pages/privacy.asp&quot;&gt;Legal Notice.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cnatra.navy.mil/pubs/folder5/T45/P-1211.PDF&quot;&gt;Link to document&lt;/a&gt; provided by CNATRA.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="65" LastEditDate="2015-03-03T15:36:02.780" LastActivityDate="2015-03-03T15:36:02.780" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9753" PostTypeId="1" CreationDate="2014-11-18T00:09:56.410" Score="0" ViewCount="204" Body="&lt;p&gt;I know a similar question was asked here before, but there is a difference:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say person X is on a flight from Pakistan to Canada on PIA (national carrier of Pakistan). The aircraft lands at, say, Toronto Pearson Airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I gather after reading the Tokyo Convention, the aircraft is no longer in flight once the airplane doors have been opened for disembarkation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an offence occurred on the airplane once the doors have been opened for disembarkation, which country is responsible for prosecution? The country where the aircraft is registered or the country where the plane has landed?&lt;/p&gt;&#xA;" OwnerUserId="4300" LastActivityDate="2014-11-18T02:36:19.010" Title="Crimes committed on board" Tags="&lt;aircraft-registration&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2014-11-18T08:25:16.037" ContentLicense="CC BY-SA 3.0" />
  <row Id="9754" PostTypeId="2" ParentId="9722" CreationDate="2014-11-18T00:58:58.117" Score="5" Body="&lt;p&gt;There's no specification for a pattern of flashing, and significant variations exist among different airlines and military. There is a uniform requirement for position lights (steady red and green on the left and right wingtips, white on the tail) and an anti-collision light &lt;em&gt;system&lt;/em&gt; which is one or more flashing lights which can be anywhere on the aircraft. US requirements are in 14 CFR 25.1401, and say that the system must appear to flash between 40 and 100 times a minute. Areas where lights overlap can have as many as 180 flashes per minute. &lt;/p&gt;&#xA;" OwnerUserId="4301" LastActivityDate="2014-11-18T00:58:58.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9755" PostTypeId="2" ParentId="9533" CreationDate="2014-11-18T01:25:50.897" Score="1" Body="&lt;p&gt;Just to put a point on the answers already here, there is no actual assigned aviation frequency 121.62. You add a 5 if the 5th digit is a 2 or a 7. Some radios display the 6th digit, some don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's further confusing where 8.33 kHz channels (in Europe, and in some special cases like flight test frequencies or company frequencies) are used. Between 121.600 and 121.625 are two other frequencies, which are actually 121.60833... and 121.61666... MHz, referred to by their &quot;channel names&quot; as 121.610 and 121.615. Eurocontrol mandates saying all six digits for the split channels.&lt;/p&gt;&#xA;" OwnerUserId="4301" LastActivityDate="2014-11-18T01:25:50.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9756" PostTypeId="2" ParentId="9543" CreationDate="2014-11-18T01:29:49.947" Score="0" Body="&lt;p&gt;There is a lot of work going on at NASA right now to take advantage of the additional lift created by propellers on the wing, which allows the wing to be thinner for the same amount of lift. Look for a series of papers coming in June of 2015 on &lt;em&gt;distributed electric propulsion&lt;/em&gt; where this is being exploited as a way to achieve additional efficiency.&lt;/p&gt;&#xA;" OwnerUserId="4301" LastActivityDate="2014-11-18T01:29:49.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9757" PostTypeId="2" ParentId="9739" CreationDate="2014-11-18T01:51:11.933" Score="1" Body="&lt;p&gt;You would ask the maker of your MCDU whether it's FANS-1 capable using just a VHF datalink. Satcom isn't necessarily a requirement, but you would only be able to use it where VDL is provided, for instance in Europe but not on oceanic routes.&lt;/p&gt;&#xA;" OwnerUserId="4301" LastActivityDate="2014-11-18T01:51:11.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9758" PostTypeId="2" ParentId="9753" CreationDate="2014-11-18T02:36:19.010" Score="1" Body="&lt;p&gt;Once the doors have been opened, it's a pretty clear case: the crime happens on some sovereign soil, and that country is responsible. They are also most likely to get custody of the criminal, which as described in the other answer is a large part of who prosecutes.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2014-11-18T02:36:19.010" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9759" PostTypeId="2" ParentId="7673" CreationDate="2014-11-18T04:22:54.863" Score="20" Body="&lt;h2&gt;Summary&lt;/h2&gt;&#xA;&lt;p&gt;If the ejection seat is inoperable on a US military aircraft, the aircraft will be grounded 100% of the time.  I'm sure you could come up with some weird hypothetical &amp;quot;end-of-the-world&amp;quot; scenario where you'd still take off, but that isn't reality today.&lt;/p&gt;&#xA;&lt;h3&gt;F/A 18 E/F Checklist Procedures&lt;/h3&gt;&#xA;&lt;p&gt;&lt;strong&gt;Interior Checklist&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;After strapping into the jet, the ejection seat is the first thing you check:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Leads, leg restraints, and harness - SECURE/ADJUST&lt;/li&gt;&#xA;&lt;li&gt;Ejection control handle - CLEAR&lt;/li&gt;&#xA;&lt;li&gt;Ejection control handle pin - VERIFY REMOVED&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;There's no point in removing the pin and checking the handle if you do not intend to arm the seats.  This is further confirmed later in the checklist.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Before Takeoff Checklist&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;[...]&lt;/li&gt;&#xA;&lt;li&gt;Harness - ATTACHED 8 POINTS&lt;/li&gt;&#xA;&lt;li&gt;[...]&lt;/li&gt;&#xA;&lt;li&gt;Seats - ARMED IN THE FRONT&lt;/li&gt;&#xA;&lt;li&gt;(2 seater) EJECT SEL - ARMED, AFT INITIATE&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;If the seats aren't armed, then the jet is never leaving the ground.  It is potentially suicidal for fighter aircraft to takeoff without ejection seats.  Fighters don't glide well (they fly to the scene of the crash), they can't fly in a total electrical failure, some can't fly without computer guidance, they can't fly with hydraulic failures, and they fly in very adverse flight conditions.  There are a lot of things, that if totally failed, would turn a fighter into a flying coffin, sans ejection seat.  Fortunately these systems are very redundant, but its usually not worth staking your life on it.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-18T04:22:54.863" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9760" PostTypeId="1" AcceptedAnswerId="9761" CreationDate="2014-11-18T08:03:05.800" Score="10" ViewCount="3988" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5SXgh.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In many discussion&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2325238/&quot; rel=&quot;noreferrer&quot;&gt;(1)&lt;/a&gt;&lt;a href=&quot;http://www.pprune.org/archive/index.php/t-335137.html&quot; rel=&quot;noreferrer&quot;&gt;(2)&lt;/a&gt; it is stated that the BAe 146 has higher maintenance cost and higher cost of operations in compare to other jets due to its complexity. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Quoting IslandHopperCO (Reply 21): The PSA (then USAir) BAe-146s were&#xA;  parked in the desert in 1991 due to high maintenance costs according&#xA;  to USAir. More likely was that USAir couldn't turn a profit on the&#xA;  western routes that PSA used to make money on, because those routes&#xA;  were dropped when the plane were parked.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No that is pretty much correct...PSA also had major problems with&#xA;  reliability. In fact BAE provided them with a spare because they broke&#xA;  down so much. Who knows if they would have gotten rid of them because&#xA;  of that. They were kinda ugly but in a cute way....that smile really&#xA;  did it!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why are the maintenance and operating cost higher?&lt;/li&gt;&#xA;&lt;li&gt;Why is it more complex than other jets?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="572" LastEditDate="2015-02-25T07:37:56.943" LastActivityDate="2016-01-31T04:51:14.697" Title="Why does the BAe 146 have higher maintenance costs than other comparable jet aircraft?" Tags="&lt;aircraft-maintenance&gt;&lt;bae-146&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9761" PostTypeId="2" ParentId="9760" CreationDate="2014-11-18T09:59:42.240" Score="10" Body="&lt;blockquote&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;higher maintenance cost and higher cost of operations in compare to other jets due to its complexity.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;That seems ironic considering what Wikipedia says&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;According to the BAe 146's chief designer, Bob Grigg, from the very start of the design process, making the aircraft as easy to maintain as possible and keeping operator's running costs as low as possible were considerably high priorities.&lt;/p&gt;&#xA;&lt;p&gt;Velupillai 1981, pp. 1245-1246, 1253.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Why is it more complex than other jets?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Because it has four engines? I believe short-haul airliners of similar capacity mostly have only two.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Why are the maintenance and operating cost higher?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Wikipedia says of the original Lycoming engines used:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The ALF 502 has experienced multiple issues. Its internal electronics could overheat, triggering an automatic shutdown of an engine with no option of in-flight restart, and certain rare atmospheric conditions could cause a loss of engine thrust due to internal icing.[29] Additionally, the BAe 146 experienced aerotoxic syndrome due to leakage of tricresyl phosphate (TCP) into its bleed air; this has been blamed on problems with leaking engine seals. Exposure to these toxic fumes is a dangerous health risk&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Note: the above is speculation, you'd have to ask an airline maintenance manager.&lt;/p&gt;&#xA;&lt;p&gt;There are interesting maintenance anecdotes / whinges at &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-362480.html&quot; rel=&quot;noreferrer&quot;&gt;pprune&lt;/a&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High price of spare parts.&lt;/li&gt;&#xA;&lt;li&gt;Accessibility of some components.&lt;/li&gt;&#xA;&lt;li&gt;N1 harness that goes through engine fan strut.&lt;/li&gt;&#xA;&lt;li&gt;Quick release fastners needed on engine core covers.&lt;/li&gt;&#xA;&lt;li&gt;FADEC harness (RJ) can't be changed without dropping the donk.&lt;/li&gt;&#xA;&lt;li&gt;Lower engine power cables that freeze full of moisture.&lt;/li&gt;&#xA;&lt;li&gt;Corrosion issuse with the gear bay longeron strut.&lt;/li&gt;&#xA;&lt;li&gt;The nose landing gear steering lube leaks out and the internals corrode&lt;/li&gt;&#xA;&lt;li&gt;Air con pacs are unreliable.&lt;/li&gt;&#xA;&lt;li&gt;Honeywell apu's are unreliable, Garrets better.&lt;/li&gt;&#xA;&lt;li&gt;Fuel tanks need proper draining off every day to get rid of moisture.&lt;/li&gt;&#xA;&lt;li&gt;Tri-wing fasteners often fail on removal.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-18T10:13:48.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9762" PostTypeId="2" ParentId="9760" CreationDate="2014-11-18T10:10:25.187" Score="9" Body="&lt;p&gt;The reason is really the number of engines. Engine maintenance is the biggest part of aircraft maintenance, and designers put as few on an airplane as they can get away with. Two is the minimum for redundancy, and any more means more hours have to be spent in the shop. This explains the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;777&lt;/a&gt; - it's the biggest thing Boeing could build once the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;noreferrer&quot;&gt;GE-90&lt;/a&gt; was announced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why the 146 has four engines is explained in the comment of @fsintegral below, but at least it helped to sell it in some cases. &lt;a href=&quot;http://en.wikipedia.org/wiki/Crossair&quot; rel=&quot;noreferrer&quot;&gt;Crossair&lt;/a&gt; used them because the owner, Felix Suter, wanted to have his own four-engine transport. The nickname for the 146 at Crossair was Jumbolino.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/British_Aerospace&quot; rel=&quot;noreferrer&quot;&gt;BAe&lt;/a&gt; sold the 146 for very low prices, so the saved money could cover the more expensive maintenance for some years.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-19T12:55:54.060" LastActivityDate="2014-11-19T12:55:54.060" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9763" PostTypeId="2" ParentId="9680" CreationDate="2014-11-18T12:57:40.560" Score="5" Body="&lt;p&gt;I will answer only for the landing gear length. When you consider large enough aircraft, you &lt;strong&gt;need&lt;/strong&gt; a long landing gear to reduce the risk of tail strike when landing and taking off. Thus, you have enough place underwing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example compare the length of the nose landing gear of an aircraft whose engines are mounted underwing (e.g. this &lt;a href=&quot;http://www.airliners.net/photo/Canadian-Airlines/Airbus-A320-211/0170966/&amp;amp;sid=df8cff884ba13601487656270ccd1dd2&quot; rel=&quot;noreferrer&quot;&gt;A320&lt;/a&gt;) with the one of an aircraft whose engines are not mounted underwing (e.g. this &lt;a href=&quot;http://www.airliners.net/photo/Aero-Lloyd/Sud-SE-210-Caravelle/1461183/&amp;amp;sid=eb6ee930349342e665767e59ad1e8a5e&quot; rel=&quot;noreferrer&quot;&gt;Caravelle&lt;/a&gt;). I choose photos with a man near to the landing gear to ease comparison.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2014-11-18T12:57:40.560" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9764" PostTypeId="1" AcceptedAnswerId="9765" CreationDate="2014-11-18T13:20:22.317" Score="34" ViewCount="11958" Body="&lt;p&gt;Note: I'm not a pilot, so I don't have much basic knowledge of how the pilot licence ratings work&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot doesn't have an Instrument Rating, and the weather conditions drop below VMC; what do they do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably you can't instantly land, but nor can you safely continue to fly without sufficient visibility?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the basic licence includes some instrument training, but is this enough to fly and land without visibility? I was under the impression that was the entire point of gaining an Instrument Rating... To train the pilot to fly on instruments alone&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-05-28T00:43:12.107" Title="What happens when a pilot has no Instrument Rating and visibility drops?" Tags="&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;&lt;vmc&gt;" AnswerCount="9" CommentCount="22" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9765" PostTypeId="2" ParentId="9764" CreationDate="2014-11-18T13:40:49.497" Score="39" Body="&lt;p&gt;It is very rare for weather to go IMC unexpectedly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A responsible pilot should see that weather is deteriorating, and begin planning for the nearest available landing.   If they cannot find a landing, they should contact ATC while still in VMC, declare an emergency, and begin working with ATC to get down safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, a pilot may inadvertently enter IMC unexpectedly.   The standard procedure is to execute a standard rate 180&amp;deg; turn, and fly equal time in the opposite direction.  That &lt;em&gt;should&lt;/em&gt; get them back to VMC conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that doesn't work, unfortunately inadvertent flight into IMC is a leading cause of GA accidents, especially CFIT (Controlled Flight into Terrain - i.e. 'aircraft flew into the ground').   Because of that, even basic private pilot training includes more basic instructions on instrument flying (BAI) than it used to.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-11-24T18:38:56.297" LastActivityDate="2014-11-24T18:38:56.297" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9766" PostTypeId="2" ParentId="9764" CreationDate="2014-11-18T13:53:59.510" Score="28" Body="&lt;p&gt;A visual pilot flying into instrument conditions is a serious emergency. It's much better to avoid the situation in the first place which is why there's a significant amount of training around preventing that from happening , namely in learning meteorology and practicing good flight planning. Pilots should always be looking out for deteriorating conditions, and planning an escape route, or a precautionary landing, even if it's in a field. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual training pilots get for inadvertent flight into IMC is to do a 180 degree turn on instruments while maintaining a stable altitude, and then fly out of the cloud they've gotten into. This won't always work, it is possible to get into IMC gradually, especially at night or over the sea (It's happened to me but I have an instrument rating so no big deal), or have IMC conditions form over an area all at once. In these situations a 180 degree turn isn't going to get a pilot to safety so they should:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Don't panic, you will get through it &lt;/li&gt;&#xA;&lt;li&gt;Fly the airplane: concentrate on maintaining controlled, level flight. The artificial horizon is your bestest friend in the whole wide world right now, but don't forget to check your other instruments and do your regular engine checks and carb heat&lt;/li&gt;&#xA;&lt;li&gt;Get your aircraft set up for flight in cloud or bad visibility, so pitot heat on, navigation lights on&lt;/li&gt;&#xA;&lt;li&gt;Call air traffic control if available, notify them of the situation and ask for assistance. ATC can help the pilot find an area with better visibility, or direct him/her to an airfield with instrument landing facilities. They can also get someone on to help talk the pilot through setting the instruments available for an instrument landing, or do a surveillance radar approach&lt;/li&gt;&#xA;&lt;li&gt;Use navigation aids to keep aware of location and to keep clear of obstacles. ATC will probably direct you, but you still need to be aware of your location and situation. If there's no ATC it's all up to you, so fly yourself to the biggest airport around, or one with lots of space and as little terrain as possible. Climb if necessary to avoid the tallest obstacle around&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-11-18T13:53:59.510" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="9767" PostTypeId="1" AcceptedAnswerId="9768" CreationDate="2014-11-18T16:15:42.237" Score="7" ViewCount="1407" Body="&lt;p&gt;Watching &lt;a href=&quot;http://www.youtube.com/watch?v=rLiZBsbWv-0&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt; I was asking myself, what was the error or cause of this unsuccessful take-off?&lt;/p&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2014-11-18T16:26:22.873" Title="Why was this Twin-Otter Take-Off unsuccessful?" Tags="&lt;takeoff&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9768" PostTypeId="2" ParentId="9767" CreationDate="2014-11-18T16:26:22.873" Score="9" Body="&lt;p&gt;Comments under the video say clearly:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Transportation Safety Board (Canada) report # AO7W0128,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Take-off weight did not meet performance capabilities of the Aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Calculations to clear 50ft obstacle were not performed.&lt;/li&gt;&#xA;&lt;li&gt;Southeast end of runway, not clearly marked.&lt;/li&gt;&#xA;&lt;li&gt;Take-off was attempted in an up slope direction with a slight tailwind which increased the necessary distance to clear a 50ft obstacle.&lt;/li&gt;&#xA;&lt;li&gt;Center of gravity (CG) calculations were off and found to be too far forward.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="43" LastActivityDate="2014-11-18T16:26:22.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9769" PostTypeId="2" ParentId="9764" CreationDate="2014-11-18T16:34:49.450" Score="5" Body="&lt;p&gt;Can't believe no one mentioned it, but first you need to transition to instruments. Then climb to at least the MEF (Maximum Elevation Figure [the number in the quadrangles on a VFR sectional]) or preferably a MIA (Minimum IFR Altitude) if you happen to know it, but do not climb into class A airspace unless it's an emergency.  Exit IMC (instrument meteorological conditions) by changing heading OR altitude (i.e. 180 degree turn).  If that doesn't work then squawk 7700 and attempt to contact the nearest controlling facility.  Do not squawk 7700 if you are instrument rated, just pick up an IFR (instrument flight rules) clearance...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, I've always learned the 5 C's apply to the lost scenario, but I suppose it could work in this case.  Never thought of it!&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorDisplayName="user3309" LastEditDate="2014-11-23T20:39:01.387" LastActivityDate="2014-11-23T20:39:01.387" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9770" PostTypeId="2" ParentId="9764" CreationDate="2014-11-18T17:06:42.307" Score="17" Body="&lt;p&gt;Special case: our university has an &lt;em&gt;exceedingly&lt;/em&gt; good &lt;a href=&quot;http://www.avidyne.com/products/dfc100/index.asp&quot;&gt;autopilot&lt;/a&gt; installed in all of our trainers.  If one of our private pilot students gets into IMC by mistake, they hit the button marked &quot;Straight &amp;amp; Level&quot; and then let &lt;a href=&quot;http://i190.photobucket.com/albums/z35/royone_bucket/Airplane%20captures/inflating-2.jpg&quot;&gt;Otto&lt;/a&gt; fly the 180 turn to exit IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not every student or private pilot has access to the level of cockpit automation that we do, even a wing leveler + elevator trim might be enough to keep you alive until you can get your bearings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an anecdote, my first time in IMC, I had over three hours of hood time, I had been fully briefed on what to expect and I knew that my body was going to lie to me.  Not more than thirty seconds in the cloud and I &lt;strong&gt;knew beyond a shadow of a doubt&lt;/strong&gt; that the airplane was &lt;a href=&quot;http://en.wikipedia.org/wiki/Sensory_illusions_in_aviation#Inversion_illusion&quot;&gt;tumbling backwards&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;If my instructor hadn't been there I would have pushed the nose into the dirt and held it there until I broke out of the cloud or hit the ground.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-11-18T17:06:42.307" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9771" PostTypeId="1" AcceptedAnswerId="9773" CreationDate="2014-11-18T17:20:36.247" Score="32" ViewCount="60531" Body="&lt;p&gt;I was told recently that if you are flying on your own private jet, you can drive your car directly on to the runway, park next to your plane and board without any security checks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can't be true can it? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I don't own my own private jet so I'm afraid I can't check for myself.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does security work around privately owned planes landing in public airports?&lt;/p&gt;&#xA;" OwnerUserId="4307" LastEditorUserId="15311" LastEditDate="2020-04-04T13:09:37.327" LastActivityDate="2020-04-04T13:09:37.327" Title="How does security and baggage checking work in regards to a private jet?" Tags="&lt;airport&gt;&lt;security&gt;&lt;private-jets&gt;" AnswerCount="6" CommentCount="15" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9772" PostTypeId="2" ParentId="9771" CreationDate="2014-11-18T17:27:53.193" Score="5" Body="&lt;p&gt;Depending on the airport you will be checked when entering the airfield itself. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will be guards at the gate that will do a quick check on your vehicle baggage and person and provide a quick safety brief (as in &quot;don't drive outside designated areas, planes have right of way&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everyone entering the safe area of an international airport will be checked, even employees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However small private airfields won't have such checks depending on who owns it.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-11-18T17:27:53.193" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9773" PostTypeId="2" ParentId="9771" CreationDate="2014-11-18T18:04:41.357" Score="31" Body="&lt;p&gt;Here in the US (you didn't specify where, and this is different in other countries), traveling domestically in your own private aircraft is much like traveling in your own private car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except in very specific situations, you are not generally required to go through security, and at many, many smaller general aviation airports airport security is almost non-existent, or at the very least they are not checking passengers and their luggage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the police have a reason to suspect that something illegal is taking place (they have reasonable cause) then they can search the airplane, but again, much like in your car, this doesn't usually happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;International flights are a very different matter though, and the airplane, crew, passengers, and luggage must all clear customs at departure and arrival airports where they will be inspected.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2014-11-18T18:04:41.357" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9774" PostTypeId="2" ParentId="9771" CreationDate="2014-11-18T18:40:12.253" Score="12" Body="&lt;p&gt;In the US this is (sort-of) true: For private aviation the responsibility for security of the flight falls on the operator of the flight, which usually means the crew is handling any &quot;screening&quot; of passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically if you're flying on a private aircraft you're a known quantity: Executives flying around in GM's jets are going to be GM employees (or their guests), folks flying around on a sports team's jet will probably be the players and coaches, etc.&lt;br&gt;&#xA;In both of those cases chances are the passengers have met the pilots before, and neither they nor their guests are likely to try to hijack the flight so there's no need for TSA-style searches and confiscation of the bottle of 30-year-old Glenlivet they brought to share on the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly for charter flights the folks renting the plane will have spoken to the company extensively in arranging the flight. There may be some additional level of scrutiny here to make sure someone's not bringing a propane camp stove or something else prohibited on board, but chances are you will not be asked to remove your shoes and belt.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The level of security for the airport itself will vary depending on the airport (and this is what usually determines if you can drive right up to the aircraft).&lt;br&gt;&#xA;Let's consider three examples (for the sake of a prison metaphor we'll call them maximum security, medium security, and minimum security):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A maximum security airport would be the &quot;big&quot; airports (like JFK or O'Hare) - At these airports chances are you will not be driving your car or limo onto the ramp to board your plane. You will park (or be dropped off) &quot;landside&quot; (outside the airport fence / operations area), and authorized persons will take your bags and escort you to and from the aircraft.&lt;br&gt;&#xA;When not on the way to or from the aircraft you'll be in a nice terminal building (&lt;a href=&quot;http://www.sheltairaviation.com/new-york-fbos/jamaica&quot; rel=&quot;nofollow noreferrer&quot;&gt;like this one&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The medium security airports are typically the larger general aviation fields and/or the smaller commercial/airline fields. If your aircraft is based at one of these airports you will typically have reasonably unfettered access to it (subject to a few restrictions, such as the need for a background check and ID badge). You will usually be able to drive out onto the ramp and go directly into the aircraft. &#xA;If you're not based at the field (for example on the return leg of a business trip) you may be allowed to drive out on the ramp with an escort from someone at the airport who is authorized to do so, but visiting crew and passengers will be under some level of supervision from airport personnel (either directly escorted or visual observation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Minimum security airports are more associated with light general aviation than business jets, though you'll find private jets based at some of these fields.&lt;br&gt;&#xA;Security is generally much more relaxed at these airports, and at most of them you simply sign in and drive through a gate right onto the ramp.&lt;br&gt;&#xA;Good common sense says passengers will usually be escorted by some qualified personnel at these fields (after all you don't want them walking into a propeller or getting sucked into a jet intake), but the supervision is probably going to be provided by your flight crew rather than airport personnel.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2017-02-17T10:03:12.517" LastActivityDate="2017-02-17T10:03:12.517" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9775" PostTypeId="2" ParentId="9771" CreationDate="2014-11-18T18:42:21.230" Score="17" Body="&lt;p&gt;The reason the TSA searches baggage going onto commercial flights is to prevent people from hijacking or destroying commercial airliners&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are going on your own private plane, you can bring scissors or just about anything you like on your own plane, since you're already the pilot and if you want to fly it to Cuba or crash it into Monsanto headquarters, a baggage search won't stop you.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Informally, other reasons are also to milk money and perpetuate perverse political ideas and acceptance of pervasive security.) &lt;/p&gt;&#xA;" OwnerUserId="3665" LastEditorUserId="65" LastEditDate="2016-04-07T23:27:47.850" LastActivityDate="2016-04-07T23:27:47.850" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9776" PostTypeId="1" AcceptedAnswerId="9777" CreationDate="2014-11-18T18:44:03.863" Score="6" ViewCount="2842" Body="&lt;p&gt;I want to start planespotting and I'm looking for the best and mosts accurate registration book.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want this book to be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;accurate&lt;/li&gt;&#xA;&lt;li&gt;checkable (to check planes I have seen)&lt;/li&gt;&#xA;&lt;li&gt;have almost every plane&lt;/li&gt;&#xA;&lt;li&gt;codes (IATA | ICAO)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If anyone knows a book I would love to hear it!&lt;/p&gt;&#xA;" OwnerUserId="3631" LastEditorUserId="572" LastEditDate="2015-02-25T07:37:29.890" LastActivityDate="2015-02-25T07:37:29.890" Title="Are there any accurate books that help with identifying aircraft when planespotting?" Tags="&lt;plane-spotting&gt;&lt;books&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9777" PostTypeId="2" ParentId="9776" CreationDate="2014-11-18T19:21:29.783" Score="4" Body="&lt;p&gt;The best option is probably &lt;em&gt;Jane’s Aircraft Recognition Guide&lt;/em&gt;. It is hard to find, but it has a large number of planes and has multiple editions.&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2014-11-18T19:21:29.783" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9778" PostTypeId="2" ParentId="9764" CreationDate="2014-11-18T20:43:23.190" Score="8" Body="&lt;p&gt;As others have said, this situation is best avoided. There's a term for trying to sneak under the clouds: scud-running. It can be deadly. As the dew point drops, the cloud ceiling falls. Combine that with rising terrain and accidents can happen. The spread between the dew point and the air temperature is a critical tool (the higher the better) for avoiding low ceilings. This is why the dew point and air temperature are part of weather information. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's really critical to understand how disorienting IMC can be. You &lt;em&gt;have&lt;/em&gt; to resist the temptation to fly with your eyes out the windscreen and switch to flying using the instruments. The expression &quot;flying by the seat of your pants&quot; is used a lot and it's just not true. One of my instructors wanted me to experience how undependable this is. He had me close my eyes and attempt to fly straight and level. After about 20 seconds, he told me to open my eyes. I was banked left about 20 degrees in a nose down attitude. While I had my eyes closed, I was certain that I was rolling to the right and climbing. That was a sobering lesson. &lt;/p&gt;&#xA;" OwnerUserId="3211" LastEditorUserId="3211" LastEditDate="2014-11-19T18:29:51.047" LastActivityDate="2014-11-19T18:29:51.047" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9779" PostTypeId="1" AcceptedAnswerId="9781" CreationDate="2014-11-18T21:09:49.907" Score="9" ViewCount="1178" Body="&lt;p&gt;Every air-launched aircraft I'm aware of, with the exception of the D-21 in combination with the M-21 carrier, has been launched by dropping it. Is there a reason why drop launches are preferred to &quot;fly-off&quot; launches from the top of the carrier?&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="572" LastEditDate="2015-02-25T07:36:32.483" LastActivityDate="2015-09-11T14:54:01.410" Title="Why are piggyback launches done by dropping the carried aircraft and not by &quot;fly-off&quot; launches?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9780" PostTypeId="2" ParentId="9779" CreationDate="2014-11-18T21:37:21.660" Score="11" Body="&lt;p&gt;The test launches of the space shuttle (both US and USSR) were top launches. (though that was due to bulk more than aerodynamic considerations)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JbShv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drop launches get you out of the wake of the carrier faster and it is easier to get vertical separation by dropping than by climbing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With fly-off you start in the turbulent area and then need to get enough speed to fly, and stay in front or above of the launching craft until flight has stabilized.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-09-11T14:54:01.410" LastActivityDate="2015-09-11T14:54:01.410" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9781" PostTypeId="2" ParentId="9779" CreationDate="2014-11-18T22:10:08.667" Score="13" Body="&lt;p&gt;Its much safer, you don't kill the carrier aircraft if you drop away and have a major aircraft malfunction.  Gravity gives you the separation you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you treat the two aircraft like a formation flight, which it essentially is, its dangerous for the critical aircraft to go belly up, ie blind, to the carrier.  In an emergency the first step in formation flying is to ensure separation which the critical aircraft can't do because it can't see if it's clear to descend and it may not have the ability to laterally sidestep.  Thus, a blind push on the nose could kill both aircrews.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-18T22:18:03.897" LastActivityDate="2014-11-18T22:18:03.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9783" PostTypeId="2" ParentId="9703" CreationDate="2014-11-19T01:14:10.447" Score="12" Body="&lt;p&gt;For military aircraft on &quot;alert&quot;, there is a position called &lt;em&gt;cocked on&lt;/em&gt; (or as some news sites call it, &quot;&lt;a href=&quot;http://www.washingtonpost.com/local/f-16-pilot-was-ready-to-give-her-life-on-sept-11/2011/09/06/gIQAMpcODK_story.html&quot; rel=&quot;noreferrer&quot;&gt;hot-cocked&lt;/a&gt;&quot;).  This procedure is run before the aircraft is placed on alert, and does a pre-flight check of all the instruments and then places them in a state that allows power application in a rapid manner.  This way, only minimal steps are required for the aircraft to be ready.  In addition to cocking on the aircraft, they can be parked in special areas (some are called Christmas Trees because of their appearance). This allows the aircraft to reach the runway quickly. Also, in the old SIOP days, there was an &lt;a href=&quot;http://en.wikipedia.org/wiki/Loring_Air_Force_Base_Alert_Area&quot; rel=&quot;noreferrer&quot;&gt;Alert Facility&lt;/a&gt; near where the aircraft were parked, where the crew would stay in a state of readiness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MXvs3.jpg&quot; alt=&quot;An Alert Christmas Tree&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently the full &lt;a href=&quot;http://en.wikipedia.org/wiki/Single_Integrated_Operational_Plan&quot; rel=&quot;noreferrer&quot;&gt;SIOP&lt;/a&gt; mission isn't active (it was ended in 1992 by President Bush, but there are still forces dedicated to it in a new capacity). However, the facilities still exist on many bases.  They can use these facilities still for whatever alerts are required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With an aircraft in cocked on position, with a pilot on alert (cockpit or facility), an aircraft can take off in a very, very short time (from seconds to minutes).  In general, the mission requirements will dictate the amount of time that the pilot is given to take off (as you note in your question).  So sadly, I can't give a &lt;em&gt;specific&lt;/em&gt; answer to your question, because it depends on parameters you haven't specified.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastEditorUserId="3268" LastEditDate="2014-11-19T15:43:33.380" LastActivityDate="2014-11-19T15:43:33.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9784" PostTypeId="1" AcceptedAnswerId="9785" CreationDate="2014-11-19T02:15:18.010" Score="9" ViewCount="1209" Body="&lt;p&gt;If an aircraft has a movable payload (e.g. camera) attached to it, two of the status modes are caged and stowed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stowed indicates the payload is retracted and or in a locked position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is caged?  I have found reference to &quot;caged&quot; in a couple of resources online, but the do not explain the term.  In some documents about passenger aircraft, it refers to cages in the luggage compartment, but this is completely different.&lt;/p&gt;&#xA;" OwnerUserId="3235" LastEditorUserId="97" LastEditDate="2014-11-19T02:24:26.373" LastActivityDate="2014-11-19T02:35:22.660" Title="What does it mean for a payload to be &quot;caged&quot;?" Tags="&lt;aircraft-systems&gt;&lt;terminology&gt;&lt;payload&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9785" PostTypeId="2" ParentId="9784" CreationDate="2014-11-19T02:35:22.660" Score="12" Body="&lt;p&gt;For something like a movable camera in a gimbal, or even a gyroscopic attitude indicator, it means that it is physically locked into place so that it can't move. On the gimbals (such as the camera pod in a predator, or other ISR asset) that can mean the camera is rotated into a stowed position, and then a pin is mechanically moved into place to keep the payload from moving.  This is usually done to prevent damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a gyroscopic attitude indicator, you can generally cage it by pulling out a knob, and rotating it to a specific setting.  Again, this physically locks it into place so that it doesn't move.  This is usually done prior to shutting down as the mechanisms keeping the gyros spinning are powered down.  This is to prevent damage as well as give it a safe position from which to start from when power is re, applied to the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3266" LastActivityDate="2014-11-19T02:35:22.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9786" PostTypeId="1" CreationDate="2014-11-19T03:20:44.040" Score="7" ViewCount="619" Body="&lt;p&gt;Recently, I heard Airbus want to make an &lt;a href=&quot;http://www.news.com.au/travel/travel-updates/airbus-submits-patent-for-flying-doughnut-design/story-e6frfq80-1227126881897&quot;&gt;aircraft that looks like a UFO&lt;/a&gt;.  Is there currently any civilian passenger plane designed with the seating in a round area rather than the traditional design with a long aisle?&lt;/p&gt;&#xA;" OwnerUserId="4315" LastEditorUserId="946" LastEditDate="2014-11-19T11:51:55.913" LastActivityDate="2015-02-18T19:52:34.183" Title="Are there any civilian planes with seating arranged in a round area?" Tags="&lt;aircraft-design&gt;&lt;airlines&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9787" PostTypeId="1" AcceptedAnswerId="9792" CreationDate="2014-11-19T04:57:25.107" Score="6" ViewCount="2335" Body="&lt;p&gt;There is a new quadcopter being launched on &lt;a href=&quot;https://www.indiegogo.com/projects/ghost-drone-aerial-filming-has-never-been-easier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Indiegogo&lt;/a&gt; that has the quadcopter motors positioned on the top of the propellers as opposed to being positioned on the bottom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any advantage to this or is it just for looks?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YLlBA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4317" LastEditorUserId="65" LastEditDate="2014-11-19T21:28:02.257" LastActivityDate="2014-11-21T03:18:56.117" Title="Is there a benefit to having the motors for a multi-rotor copter on the top vs the bottom of the frame?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9789" PostTypeId="1" CreationDate="2014-11-19T06:51:00.827" Score="6" ViewCount="912" Body="&lt;p&gt;When taxiing, taking off and rolling out we are told to use cross-wind correction inputs. Assuming a headwind, you bank into the wind by raising the aileron on the windward side and lowering the other aileron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it appears that just before you take off, even with the wings level, holding the ailerons as above helps the plane avoid skidding sideways on its wheels. I understand the physics once you are airborne and the wings are no longer level (you will slip into the wind). But what I don’t understand is why holding up aileron on the windward side helps prevent skidding sideways, &lt;strong&gt;even with the wings level&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do the physics work to prevent sideways force on the gear? Or am I imagining that the wings are level and in fact the windward wing is lowered?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I’ve felt this more strongly in a Citabria 7ECA or similar light tailwheel, high-wing aircraft, but I think it also applies to a tricycle-gear C172 or similar.&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="1696" LastEditDate="2015-12-14T15:56:38.553" LastActivityDate="2015-12-14T16:30:14.510" Title="How do cross-wind correction controls help while on the ground with wings level?" Tags="&lt;flight-controls&gt;&lt;crosswind&gt;&lt;aircraft-physics&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9791" PostTypeId="2" ParentId="9789" CreationDate="2014-11-19T07:51:41.443" Score="1" Body="&lt;p&gt;Your assumption is that the wings are level when both main wheels are on the ground. But this is not necessarily true. Even when both wheels are on the ground, the wings can still have a small tilt. The suspension of each gear works independent of the other, and the weight on the wheel determines how much the suspension compresses or the gear strut will bend. By deflecting the ailerons, you re-distribute the lift between the wings, and control gear compression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that with the ailerons level, your wing will create a sizable rolling moment in a crosswind, which means that the load distribution between the two main wheels is uneven without aileron correction. Also, the fuselage will create a side force of its own, and this force increases with speed as more of the flow around the fuselage will be attached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slight tilt angle of the wing also slightly tilts the lift vector, and this, together with the side force of the fuselage, creates the side force which causes the skidding when this side force is large in comparison with the low load on the wheels shortly before takeoff. You need to tilt the wing into the crosswind to create a counter-force which can compensate the side force of the fuselage, only then the whole aircraft will not experience a side force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know, the picture below shows a glider and not a Citabria, but the principle is the same. The high wing arrangement creates a sizable rolling moment even without dihedral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N19iV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="7532" LastEditDate="2015-12-14T16:30:14.510" LastActivityDate="2015-12-14T16:30:14.510" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="9792" PostTypeId="2" ParentId="9787" CreationDate="2014-11-19T09:06:29.287" Score="4" Body="&lt;p&gt;It could be just for looks, but rotor placement has a noticeable effect on the behaviour of the quadcopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher the rotors are on the frame the higher the center of lift will be (the center of lift for quadcopters is the center of the plane created by the rotors.) A high center of lift means that the frame will be more stable. A low center of lift means the opposite. The reason for that is that the quadcopter can better naturally deal with lateral rotational forces on its frame. The center of lift being above the center of mass means that the frame is &quot;hanging&quot; like a pendulum from it. If you apply a lateral force to it, it will naturally swing back to place and the more you push the &quot;harder&quot; it becomes to move the frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A center of lift that is in the same spot as the center of mass of the frame means that there is no pendulum effect. This is like balancing a ball on top of another ball. All lateral forces, either internal like variations on each rotors' force or external like wind perturbations have maximum effect in moving the frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrary to what you might think, stability is not something you want in a quadcopter. The more unstable the frame, the more &lt;em&gt;agile&lt;/em&gt; it becomes. Small variations in rotor force will create large rotational movements. The penalty you pay for that (small, unpredictable external forces also create large rotational movements) you make up with processing power. Processors are now so fast and sensors so sensitive that they easily can compute the external forces and create a response fast enough to keep the frame flying.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastActivityDate="2014-11-19T09:06:29.287" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9793" PostTypeId="2" ParentId="9776" CreationDate="2014-11-19T10:34:41.707" Score="2" Body="&lt;p&gt;I confirm the &lt;strong&gt;&lt;em&gt;best option&lt;/em&gt;&lt;/strong&gt; is the one &lt;a href=&quot;https://aviation.stackexchange.com/a/9777/3879&quot;&gt;proposed by Peter and voretaq7&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However [personal opinion]&lt;/strong&gt;, I think it won't fulfill three main requirements in spotting :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;precision&lt;/li&gt;&#xA;&lt;li&gt;contains almost every plane&lt;/li&gt;&#xA;&lt;li&gt;portable&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I have the french version of that book (because I'm french speaking)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Precision&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Precision&lt;/strong&gt; is what you need to spot the differences between an A318 and an A319 (or a 737-600 and a 737-700) for example. Using the number of passenger windows count/number of exits. Knowing for example a 737-300 can have winglets and no cockpit eyebrows since a dozen years avoids confusion with a 737-700 by looking at the &lt;strong&gt;other differences&lt;/strong&gt; (engines, tail height/size, wingspan, wingroot, flaps slats, spoilers, no winglets wingtip, stabilizers, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt; you don't have in &lt;strong&gt;&lt;em&gt;that&lt;/em&gt;&lt;/strong&gt; book, but you rather gather by experience and curiosity elsewhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The book just provide you - per featured model -&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;one arbitrary picture of the plane (sometimes granny)&lt;/li&gt;&#xA;&lt;li&gt;one 3-views, mostly left, top (or bottom) and front.&lt;/li&gt;&#xA;&lt;li&gt;a brief historic description&lt;/li&gt;&#xA;&lt;li&gt;a non exhaustive list of most common produced versions in bold with one specific information that makes this version different from others (mostly the operation type like &quot;cargo version&quot;, or increased MTOW..)&lt;/li&gt;&#xA;&lt;li&gt;a non exhaustive list of weapons for military aircraft, role and operators if a few countries operate the model.&lt;/li&gt;&#xA;&lt;li&gt;a resumee of its caracteristics (seats, payload, speed, range)&lt;/li&gt;&#xA;&lt;li&gt;its dimensions (wingspan, overall length, height)&lt;/li&gt;&#xA;&lt;li&gt;and a brief way to describe the general looking of the plane (hight/low mounted wings, engines location, model and manufacturer, number of fans for propellers, stabilizers location, one very noticeable caracteristics if any like domes, fuel pods, cargo pod..)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The arbitrary picture can help recognising the aircraft, but seen from other directions, it doesn't help much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By experience, 3 views doesn't well represent 3D or field depth, as every component is flattened on a drawing (I'm modeling 3D airplanes/Aircraft profiles) Note : some drawings in the book contains minor errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The historic description is of no real use in spotting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, model versions are not really relevant, since most aircraft are customizable (mainly commercial aviation) Military aircraft are usually multirole. This kind of information is only useful for someone actually operating/working on the model (ie a pilot or engineer or reproducing the model (3D/scale model)) Weapons loadings greatly vary per mission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general looking description is too broad/vague to get a perfect match. Its purpose is more to class a given model in a group of similar models to narrow the identification process to one or two dozens of aircraft than precisely describe the model.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Every plane ?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Impossible&lt;/strong&gt; ! The book contains commercial, military, fixed wings, tiltrotor, general aviation, utility... It doesn't even contain soaring light weight planes. And you already have several hundreds models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some models has to be merged to fit in a single page, like the 737NGs, A330s, B767/777, ERJ17x/19x... (And I'm not talking for military ones)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, most common models are covered, but if you're spotting a Bizjet landing in Heathrow it could take a while before you can clearly confirme it's a Gulfstream V rather than a Gulfstream IV. Worse, when you're looking for single engine propeller. Even worse if the aircraft you're spotting isn't featured in the book, then you could assume it's model X while it isn't.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Portable ?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To have every planes and be precise, you'll end with the encyclopedic version which is actually two very large books with hundreds of pages. You'll look weird bringing those with you while spotting, &lt;strong&gt;and&lt;/strong&gt; it will take even longer to parse it to find your model...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ie : don't !&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What I mean is, you can't have enough info in a book that will &lt;em&gt;really&lt;/em&gt; help you identify &lt;strong&gt;any&lt;/strong&gt; airplane on first sight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;Dont mistaken me - note for others aswell :&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This book is an &lt;strong&gt;extremely valuable&lt;/strong&gt; one and is &lt;strong&gt;worth its price&lt;/strong&gt;, really ! &#xA;  I'm enjoying it very much and has proven &lt;strong&gt;useful&lt;/strong&gt; countless times for me.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;...but not in spotting !&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This book is the best option I know.. as a book.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm just answering the question &lt;em&gt;&quot;Looking for the most accurate planespotter book&quot;&lt;/em&gt; and this book is the one that approximates well the OP's requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But honestly, I think no book will ever fit your needs, unless it's an application on a tablet you can do queries, and contains a huge database of planes in the world with enough informations. I'm not aware of such any application (because I don't have/use/like tablets)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have time to read a book, I would rather suggest to spend that time to visit some spotting sites like Airliners.net or Planespotters.net, forums like Airlinercafe.com aswell as manufacturer's websites, looking for technical documents in PDF format.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Identifying a plane at first glimpse is not a matter of having a tool doing it for you. It's more beeing used look at that plane from different spotting angles, noticing the bits that makes it different from other models, &lt;strong&gt;and memorizing that&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, there are some useful informations you can get by &lt;strong&gt;not&lt;/strong&gt; reading a book but, rather crawling the web (unless you're a &lt;em&gt;collectionneur&lt;/em&gt; that has bought thousands books, one dedicated to a particular model) For example, I always had the feeling there was something weird between the Boeing 707(-320) fuselage and the 727s/737s ones. But I couldn't find out what until I read somwhere that &lt;em&gt;&quot;since 727s and 737s are rather short/medium ranges models, it wasn't required to have as much space in the cargo belly. Boeing decided to shrink the lower part of the fuselage.&quot;&lt;/em&gt; That's why 707 noses looks &quot;sharper&quot; than 727/737s...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;PS : each page of the book is rather filled with datas. You don't have much space to add notes, but you can mark a cross though that means you've spotted the plane :) But it would only apply to the (few) pages of the models flying in your region (unless you're a serial traveller and international spotter...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The book doesn't have IATA/ICAO listing of each airplane. It's rather intended to lambda aviation enthusiasts than the few looking for such specific piece of information.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-11-19T10:34:41.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9795" PostTypeId="1" AcceptedAnswerId="9802" CreationDate="2014-11-19T12:55:12.857" Score="1" ViewCount="808" Body="&lt;p&gt;Suppose that we find that a meteor is headed for, say, Dallas, TX, and it's too late to prevent the impact. The USA has 3 days to evacuate the area before the impact. The impact is one of the size of Tunguska: it will inflict massive damage in an area about the size of London, and we will notice the impact, but it will be mostly localized damage, so there's no global climate change or widespread damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Naturally, if you need to evacuate 1.26 million people in 3 days, you want to speed up the evacuation as much as possible, so you want to use all the possible methods of evacuation, be it through air, on water or on the ground, as efficient as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an American Federal authority like FEMA, the TSA or the FAA that has guidelines on how to handle the aviation part of such an emergency evacuation? The example of a meteorite is just that, an example. The meteor itself is not that relevant, what is relevant is how they'd handle the aviation part of the evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To clarify: I'm specifically talking about the aviation related parts, so anything related to the airspace over the area, how it would affect regional passenger traffic, to what extent local airports and pilots would be involved,... I realize there are other related actions, like evacuations through the highway and route system and through waterways and canals. Those are not what I'm interested in, insofar as they're not related to air traffic and aviation.&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="2171" LastEditDate="2014-11-20T02:32:08.123" LastActivityDate="2014-11-20T02:32:08.123" Title="Are there US guidelines on how aviation is handled during an emergency situation?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="10" ClosedDate="2014-11-20T11:51:49.083" ContentLicense="CC BY-SA 3.0" />
  <row Id="9796" PostTypeId="1" AcceptedAnswerId="9801" CreationDate="2014-11-19T13:20:09.820" Score="5" ViewCount="658" Body="&lt;p&gt;A recent question on FAA &lt;a href=&quot;https://aviation.stackexchange.com/questions/9795/does-the-faa-have-guidelines-on-how-aviation-is-handled-during-an-emergency-evac&quot;&gt;handling of evacuations&lt;/a&gt; prompted me to wonder if there are ever temporary (emergency based) flight corridors set up by any of the governing authorities? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, is there ever the airspace equivalent of one way highways set up for a temporary period?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-24T06:03:13.383" Title="Are there ever temporary flight corridors?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;easa&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9797" PostTypeId="2" ParentId="9789" CreationDate="2014-11-19T14:32:04.160" Score="1" Body="&lt;p&gt;When taxiing in a crosswind, the fuselage blocks the airflow over the downwind wing (just as if it were in a slip), so the upwind wing has that much more lift than the downwind wing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if the wind gets under the upwind wing, it will just push the upwind wing further upwards, just as if you were carrying a 4x8 piece of plywood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These two factors can contribute to tipping the airplane over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With gliders, this is much more pronounced because they don't have wheels under the wings, so the ground crew always keeps the upwind wing lower in a crosswind. In a glider crosswind takeoff, full upwind aileron is applied before takeoff, and as the aircraft starts to roll, the aileron is continually reduced to keep the wings level, with downwind rudder to keep the fuselage aligned with the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now to answer your question: up aileron on the upwind wing will reduce the lift on the upwind side and increase the lift on the downwind side, to help the aircraft from sliding sideways.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-11-19T14:56:23.807" LastActivityDate="2014-11-19T14:56:23.807" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9799" PostTypeId="2" ParentId="9796" CreationDate="2014-11-19T14:46:06.397" Score="3" Body="&lt;p&gt;You could argue that any time an aircraft is given a route which is not on a permanent air corridor, a temporary one is set up, and that if a controller gives several planes a similar route, that corridor is in use&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More sensibly, no - there's no need to, there's plenty of airspace in areas with no corridors, and even if there was an unusual amount of traffic the controller would just implement a similar concept (routing aircraft along a similar route in the same direction) on an ad-hoc basis as and when required - there's no need to declare it as a corridor in some official manner and propagate that information to airlines and pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Corridors are only necessary for busy routes, and even then it's not mandatory for them to be used by ATC - it's just sensible to use them most of the time to avoid confusion&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-11-19T14:46:06.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9800" PostTypeId="2" ParentId="9796" CreationDate="2014-11-19T14:51:11.630" Score="4" Body="&lt;p&gt;Flight corridors (airways) are just standard routes to simplify communication from controllers to pilots when describing where they should fly and between controllers when handing over flights. But the controllers can assign arbitrary vectors (headings and altitudes) to aircraft whenever they see fit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there is no need to formally set up a temporary corridor. If the traffic for whatever reason does not fit the usual corridor, the controller will simply assign any free vector and explain the situation to the next controller. They do that all the time anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in non-radar environment (e.g. oceanic or in case of radar failure) airways become important tool for the air traffic control, because it would not be feasible to keep track of positions of all the aircraft on ad-hoc routes. With airways the controller knows which airways intersect so planes on them need to be separated vertically and only needs to track the aircraft progress in one dimension (along the airway) instead of two (on map).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-11-24T06:03:13.383" LastActivityDate="2014-11-24T06:03:13.383" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9801" PostTypeId="2" ParentId="9796" CreationDate="2014-11-19T14:54:46.930" Score="4" Body="&lt;p&gt;There aren't temporary flight corridors, but during emergencies, the FAA will issue temporary flight restrictions (TFRs), many of which include the following text: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;ALL AIRCRAFT ENTERING OR EXITING THE TFR MUST BE ON A DISCRETE CODE ASSIGNED BY AN AIR TRAFFIC...AIRSPACE CONTROL (ATC) FACILITY&lt;/li&gt;&#xA;  &lt;li&gt;AIRCRAFT MUST BE SQUAWKING THE DISCRETE CODE AT ALL TIMES WHILE IN THE TFR. &lt;/li&gt;&#xA;  &lt;li&gt;ALL AIRCRAFT ENTERING OR EXITING THE TFR MUST REMAIN IN TWO-WAY RADIO COMMUNICATIONS WITH ATC.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The controllers will then direct traffic in, out, and within the area as needed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, remember that aircraft separation is by altitude as well as position, and nothing prevents a controller from using all the altitudes in her airspace to vector aircraft in one direction. When assigning an altitude that contradicts the hemispherical rules, ATC will use the words &quot;wrong way&quot; to make sure you understand you are being given an altitude inappropriate for your direction of travel.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-11-19T15:01:54.330" LastActivityDate="2014-11-19T15:01:54.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9802" PostTypeId="2" ParentId="9795" CreationDate="2014-11-19T14:56:36.250" Score="10" Body="&lt;p&gt;Given the scenario described, this is highly speculative but I'll have a go anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that &lt;a href=&quot;http://www.fema.gov/&quot;&gt;FEMA&lt;/a&gt; would be responsible for the overall evacuation and indeed their &lt;a href=&quot;http://www.fema.gov/pdf/emergency/nrf/nrf-esf-01.pdf&quot;&gt;transportation annex&lt;/a&gt; says that the FAA's main responsibility in an emergency is limited to airspace management:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DOT/Federal Aviation Administration (FAA) is responsible for the&#xA;  operation and regulation of the  U.S. National Airspace System,&#xA;  including during emergencies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same document appears to rule out military control of US airspace (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Under certain conditions, DOT/FAA may delegate  use of specified&#xA;  airspace for national defense, homeland security, law enforcement, and&#xA;  response (e.g., search and rescue) missions, &lt;strong&gt;but retains control of&#xA;  the airspace at all times.&lt;/strong&gt;  DOT/FAA may also implement air traffic and&#xA;  airspace management measures such as  temporary flight restrictions in&#xA;  conjunction with these missions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In practice, the main thing the FAA would do is to set up one or more (possibly very large) &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0305.html&quot;&gt;Temporary Flight Restrictions&lt;/a&gt; to ensure that only emergency and evacuation aircraft could use the airspace around the affected area (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1137&quot;&gt;14 CFR 91.137&lt;/a&gt;). In the catastrophic scenario you described, it might be serious enough for the FAA to close the entire national airspace system to non-emergency traffic - as they did on 9/11 - because the refugees would presumably have to be taken all over the US and the evacuation would be a genuinely national crisis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from that, the FAA could provide extra ATC services by calling in controllers from vacation and/or making them work overtime; they would probably also have to implement some quick procedures to manage the increased air traffic in the area. They could waive or suspend rules on crew working hours, required aircraft maintenance or anything else that would reduce the amount of time that evacuation aircraft could spend in the air. Of course all these things would increase the risks involved in operating the aircraft, but in the face of an unavoidable disaster that would presumably be acceptable. Anyway, I guess no one would prosecute a pilot for flying overtime to save lives in such an extreme situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mobilizing GA aircraft for the evacuation is another possibility (an aviation equivalent of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dunkirk_evacuation&quot;&gt;Dunkirk evacuation&lt;/a&gt;) and the FAA could help there by setting up temporary ATC procedures, creating ad hoc control towers at smaller airports and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FEMA document linked above implies at least some planning has been done with the FAA on disaster response:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DOT/FAA Response Cells: FAA activates specialized response cells to&#xA;  manage and  coordinate air navigation services and other&#xA;  aviation-related efforts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But what FEMA and the FAA would really do in a specific situation is very speculative and has much more to do with disaster response than aviation: the aircraft are just there to move people and things around, and the real challenge is deciding how to use them.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-19T14:56:36.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9803" PostTypeId="2" ParentId="9786" CreationDate="2014-11-19T21:12:58.550" Score="6" Body="&lt;p&gt;The simple answer is &lt;strong&gt;no&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Why a round seating design is not feasible?&lt;/em&gt; We need to look at a few aspects.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Real Estate&lt;/strong&gt;&lt;br&gt;&#xA;An airplane fuselage is rectangular (roughly speaking) in shape (when viewed from top). Airplane seats are rectangles. If you place rectangular boxes in a circle, you can fit lesser number of boxes than if you place them in a rectangle of the same area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines have just one goal to achieve, i.e. &lt;strong&gt;make money&lt;/strong&gt;. Yes they take people from point A to point B too but if demand arises for joyrides, airlines will not be hesitant to start that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By fitting more people in lesser space (not in inhumane positions mind you, governments don't allow it), they make sure that their profits soar.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Loading/Unloading Passengers&lt;/strong&gt;&lt;br&gt;&#xA;In a circular configuration, people will be a lot more confused to find their seats. People are already so confused and disillusioned when boarding a regular airplane that flight attendants have to guide &lt;em&gt;every&lt;/em&gt; single person about where the seat is. Don't believe me? Notice how the flight attendant will snatch the boarding pass from your hand if you try not to show it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Servicing Meals&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airline_service_trolley&quot; rel=&quot;nofollow&quot;&gt;Trolley carts&lt;/a&gt; used in airplanes are designed for straight aisles. In case of circular aisles, it would be very hard to maneuver them because flying airplanes do get bumps every now and then.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Evacuation&lt;/strong&gt;&lt;br&gt;&#xA;In case passengers need to be evacuated, a circular design would not be very practical. Since all people will not facing forward, simple emergency instructions, e.g. move to the front/back/left/right of the airplane can be confusing and will waste time. Locating an emergency exit will be harder too than in a normal airplane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;History&lt;/strong&gt;&lt;br&gt;&#xA;People are used to the conventional design. The present design is in use for over half a century. In addition to airplanes, trains, buses, cars and buggies have the same configuration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I am not sure how that (and some other) news channel found about Airbus's new design. Airbus does disclose the &lt;a href=&quot;http://www.airbus.com/innovation/proven-concepts/&quot; rel=&quot;nofollow&quot;&gt;future innovations&lt;/a&gt; it is working on, and flying doughnut is not mentioned there. It could be that is it on paper only at the moment. The patent information mentioned in your referenced article cannot be found with &lt;a href=&quot;http://www.uspto.gov/patents-application-process/search-patents&quot; rel=&quot;nofollow&quot;&gt;United States Patent and Trademark Office&lt;/a&gt;, or at &lt;a href=&quot;http://www.google.com/advanced_patent_search&quot; rel=&quot;nofollow&quot;&gt;Google Patent Search&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-02-18T19:52:34.183" LastActivityDate="2015-02-18T19:52:34.183" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9805" PostTypeId="2" ParentId="9786" CreationDate="2014-11-20T04:18:59.213" Score="6" Body="&lt;p&gt;A number of executive / private jets have club-style seating. If you are not concerned about passenger density you can arrange the seats any way you want. I used to skydive, we would sit on the floor in any reasonable pattern depending on the plane size and load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in commercial air travel you will not find any wasted space outside of a concept drawing. The original 747 designs included using the entire upper deck as a lounge. Didn't happen in reality as the loss of revenue seats was too high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, sadly, circular seating looks neat on paper, we won't see it in reality unless it's our private plane.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-11-20T04:18:59.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9806" PostTypeId="1" AcceptedAnswerId="9807" CreationDate="2014-11-20T06:06:12.880" Score="14" ViewCount="2936" Body="&lt;p&gt;During the investigation of &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;noreferrer&quot;&gt;Malaysia Airlines Flight 370&lt;/a&gt;, it was revealed that Captain Zaharie Ahmad Shah had a sophisticated home-built flight simulator setup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cWIDK.jpg&quot; alt=&quot;Flight Simulator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(&lt;a href=&quot;http://therearenosunglasses.wordpress.com/2014/03/16/malaysian-investigators-focus-upon-politically-active-pilot-zaharies/&quot; rel=&quot;noreferrer&quot;&gt;article source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What flight simulator software is he using here?&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="65" LastEditDate="2014-11-20T13:53:17.030" LastActivityDate="2019-01-17T21:17:13.397" Title="What flight simulator software did Captain Zaharie Ahmad Shah use?" Tags="&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9807" PostTypeId="2" ParentId="9806" CreationDate="2014-11-20T07:12:15.097" Score="20" Body="&lt;p&gt;Based on the red little strip (notification bar) on the bottom of the instrument panel in the middle, it must be either &lt;a href=&quot;http://en.wikipedia.org/wiki/Microsoft_Flight_Simulator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Microsoft Flight Simulator&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_Prepar3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin Prepar3d&lt;/a&gt;. The red notifiation bar is specific to Flight Simulator 2004 (FS9) and Flight Simulator X (FSX). Laminar Research's &lt;a href=&quot;http://en.wikipedia.org/wiki/X-Plane_%28simulator%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-Plane&lt;/a&gt; uses a different graphics engine and would not have produced a scenery that looks like on the three outside view screens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The source is not really quotable, but if the name and picture can be taken a proof, then Mr Shah himself writes on the &lt;a href=&quot;http://www.x-sim.de/forum/viewtopic.php?f=3&amp;amp;t=20&amp;amp;start=110&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-Sim.de Forum&lt;/a&gt; about FS9 and FSX being used:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Elo guys,&#xA;  zaharie here.... pls to join x-sim. About a month ago I finish assembly of FSX and FS9 with&#xA;  6 monitors .... with the latest graphic card ( 2 pieces of asus 7970) on one cpu awesome view on 3 panasonic 32 in. LCD HDMI&#xA;  and 3 touchscreen Dell 21 inches for main (MCP) , center pedestal, overhead panel.&#xA;  time to take to the next level of simulation.Motion! looking for buddies to share this passion.&#xA;  Capt Zaharie Ahmad Shah&#xA;  BOEING 777 MALAYSIA AIRLINES&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Answer based on own experience with all 3 simulators/publishers.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="11215" LastEditDate="2019-01-17T21:17:13.397" LastActivityDate="2019-01-17T21:17:13.397" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="9808" PostTypeId="2" ParentId="9786" CreationDate="2014-11-20T09:21:07.053" Score="1" Body="&lt;p&gt;There are no current passenger planes that use the circular seating layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, they are certainly being considered by airline manufacturers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the main reasons, as cited in the text of the link you provided is that &quot;the design will address the ongoing problems associated with pressurised cabins that places [sic] stress on the front and back end of planes requiring heavy reinforced frames.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, when seating is organized in a circular fashion, the maximum distance between any two seats is dramatically reduced.  This can help improve passenger and employee foot traffic onboard the aircraft.  Food service can be enhanced as well as ability to quickly access a restroom.  More options for accommodating disabled passengers become possible.  Access to emergency exits can be improved when compared to a traditional seating arrangement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason for circular seating layouts is that they are often a part of designs that do not incorporate windows.  By removing the windows, the plane can be made lighter and more efficient.  All the structural reinforcements required for the windows can be removed.  Another example of a windowless design can be seen &lt;a href=&quot;http://www.engineering.com/DesignerEdge/DesignerEdgeArticles/ArticleID/7218/Spike-Aerospaces-Windowless-Jet-Gives-Passengers-a-Great-View.aspx&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with the amazing digital screens that can be incorporated in a windowless design, I personally feel that one of the best parts of flying is the direct unadulterated view through the windows.  I hope future designs ensure that passengers are always able to enjoy that unique experience.&lt;/p&gt;&#xA;" OwnerUserId="4095" LastActivityDate="2014-11-20T09:21:07.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9810" PostTypeId="5" CreationDate="2014-11-20T14:35:32.947" Score="0" Body="&lt;p&gt;Because there are several very different engine types for aircraft, you should avoid using this tag if you can use a more specific one, like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/piston-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;piston-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;piston-engine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/turboshaft&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboshaft&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboshaft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/rocket&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rocket&amp;#39;&quot; rel=&quot;tag&quot;&gt;rocket&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions where the specific engine type isn't important, isn't known or where multiple engine types are being compared.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-05-27T04:30:16.377" LastActivityDate="2019-05-27T04:30:16.377" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9811" PostTypeId="4" CreationDate="2014-11-20T14:35:32.947" Score="0" Body="For general questions related to aircraft engines; use the [jet-engine] or [piston-engine] tag if possible." OwnerUserId="62" LastEditorUserId="8282" LastEditDate="2020-01-12T18:57:26.850" LastActivityDate="2020-01-12T18:57:26.850" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9812" PostTypeId="2" ParentId="9787" CreationDate="2014-11-20T15:17:17.190" Score="1" Body="&lt;p&gt;The main reason is related to how the arms impact the thrusters' aerodynamic efficiency. The impact is lower when the arms are on the air-intake side of the propeller rather than in the downwash. It's actually quite surprising that most multi-rotors do not have downward-pointing props. One reason might be that it becomes more difficult to mechanically implement the landing skids with downward pointing props.&lt;/p&gt;&#xA;" OwnerUserId="94" LastActivityDate="2014-11-20T15:17:17.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9813" PostTypeId="1" CreationDate="2014-11-20T17:43:22.617" Score="7" ViewCount="2662" Body="&lt;p&gt;The same question goes for any runway, but I guess that for small aircraft carriers, one might actually be able to measure the exact point of weight increases (e.g. measure the submersion of the hull). For helicopters, it seems that this is the case, so I would presmue the same for fixed wing aircraft.&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2014-11-21T18:59:26.943" Title="Does an aircraft landing on a carrier increase the carrier weight before it touches down?" Tags="&lt;aircraft-physics&gt;" AnswerCount="7" CommentCount="10" ClosedDate="2014-11-21T16:21:57.500" ContentLicense="CC BY-SA 3.0" />
  <row Id="9814" PostTypeId="2" ParentId="9764" CreationDate="2014-11-20T18:04:37.613" Score="5" Body="&lt;p&gt;I read a few times that the attitude indicator is your friend. That is not so much true. Just last night I was in IMC and my attitude indicator was acting up, a 2 month old AI... If you are flying anywhere near IMC conditions, you best be well rehearsed in flying by and trusting your life in that set of instruments(all of them), 3 hours a year ago in training is not enough. If you accidentally get stuck in IMC conditions and try to feel your way out of it, you'll be ascending into the heavens within minutes. I had never been in the soup, even as a passenger, until after I got my IR. I didn't realize the skill I had developed in instrument training until I took a non IR rated private pilot into the soup with me. Every 30 seconds he was asking why we were banking so hard when we were level, or why we weren't turning when we were. Thats coming from a guy just got his license and did his 3 hours in the past 2 months or so. Thats scary. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you see IFR or degrading visibility anywhere near or around your flight, my advice is to stay on the ground&lt;/p&gt;&#xA;" OwnerUserId="4335" LastActivityDate="2014-11-20T18:04:37.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9815" PostTypeId="2" ParentId="9813" CreationDate="2014-11-20T18:29:04.433" Score="11" Body="&lt;p&gt;Excellent question! Yes indeed, it does! At least in the sense that it is pushing the carrier down. Now we have an intense discussion going on if this is weight or not. If we avoid the nitpickers and call it a downforce, I think all will agree that the landing aircraft adds a downforce equivalent to its weight to the weight of the carrier, once it is flying above the deck. Before, this downforce was acting on the water surface (and on the ocean floor ...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is created &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;by pushing air down continuously&lt;/a&gt;, and this air movement has to be stopped somehow. In the end, this stopping happens by friction as long as the aircraft is at altitude. The movement is dissipated by shear forces between the air molecules. Close to the ground the movement is not stopped by shear force, but by a pressure field. Below the aircraft is an area of higher pressure, and this pressure pushes the aircraft carrier down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the high-flying aircraft creates an area of slightly higher pressure below it, but the area is so big that the pressure increase is extremely small. In the end, the mass of the whole earth does not change when an aircraft takes off or lands somewhere.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-21T07:33:45.510" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9816" PostTypeId="2" ParentId="9787" CreationDate="2014-11-20T20:49:16.243" Score="1" Body="&lt;p&gt;@abey is right, but his answer is a little short. Let me give some background.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propellers work by accelerating air. If you think of a stream tube through which all air flows that will pass through the propeller disc, the diameter of this tube is bigger than the propeller diameter itself ahead of the propeller and smaller behind it. Since the air flows faster behind the propeller, the same mass flow needs less stream tube cross section. The propeller sucks air in, so the speed increase starts at some distance ahead, and raises pressure in the disc, so more speed increase follows behind the propeller when the pressure $p$ in the streamtube falls to the level of ambient air pressure $p_{\infty}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wurbt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A strut placed ahead of the propeller will see less dynamic pressure than one placed behind it. Turn the picture above by 90° anticlockwise, and you have a quadcopter propeller arrangement. Make the initial speed $v_{\infty}$ zero and you have the situation for a quadcopter in hovering flight. Consequence: Propellers below the strut will have a higher efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Full disclosure: The picture above is idealized - in reality, the air behind the propeller will mix with air surrounding it, which will be dragged along. The streamtube idealization gives an easy way to calculate propeller thrust when combined with the assumption of identical air speed over the cross section of the stream tube, but in reality the speed distribution is uneven, with a gradual decrease with bigger distance from the axis of symmetry.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-11-20T20:49:16.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9817" PostTypeId="2" ParentId="9813" CreationDate="2014-11-20T20:57:04.827" Score="15" Body="&lt;p&gt;No. Weight is defined as the effect of gravity on a body. Until the aircraft becomes part of the body of the carrier, it has no effect on the weight of the carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think you are confusing force with weight. For example, if wind shear drives wind against the top deck, this does not make the carrier have more weight, but it does cause the carrier to move down. Likewise any gust from an aircraft may apply a force to the carrier, but does not increase its weight. You might consider that force to increase the &quot;apparent weight&quot; of the carrier, but it cannot be said to increase the weight of the carrier itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that the downward wind force of a landing fighter is relatively slight. For example, a person can easily walk under rotating helicopter blades and still stand up and walk. The force is probably only around 1-2 pounds per square inch, maybe 5,000-15,000 pounds total. For an aircraft it will be even less.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2014-11-21T03:59:54.217" LastActivityDate="2014-11-21T03:59:54.217" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="9818" PostTypeId="1" AcceptedAnswerId="9819" CreationDate="2014-11-20T21:31:58.727" Score="16" ViewCount="2439" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_OH-58_Kiowa#OH-58D&quot; rel=&quot;noreferrer&quot;&gt;Bell OH-58D&lt;/a&gt; (a military helicopter used by the USA) has an airbag to make life better in the event of a crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eTKDH.jpg&quot; alt=&quot;AirBags&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had never heard of such a thing in an aircraft before and I wondered if this unique to the Bell OH-58 and, if not, whether civilian light aircraft come with such an option ?&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="65" LastEditDate="2014-11-20T21:53:46.810" LastActivityDate="2014-11-20T21:54:51.227" Title="Airbags in aircraft - is that just a military thing?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;military&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9819" PostTypeId="2" ParentId="9818" CreationDate="2014-11-20T21:54:51.227" Score="17" Body="&lt;p&gt;Airbag seatbelts on planes are a &quot;new&quot; thing (&lt;a href=&quot;http://www.amsafe.com/products-services/general-aviation/seatbelt-airbags/&quot;&gt;well, since about 2001 apparently&lt;/a&gt;), but they're available on new-production aircraft and can be retrofitted to older General Aviation planes as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also find them on some airliners (typically in the exit rows where the next row is too far away to assume a proper brace position).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AmSafe (the folks who make a good percentage of the aviation-approved seatbelts) &lt;a href=&quot;https://www.youtube.com/watch?v=lZfPJG3LXxk&quot;&gt;has a nice video&lt;/a&gt; (&lt;a href=&quot;https://www.youtube.com/watch?v=FboAm9RqUXM&quot;&gt;or two&lt;/a&gt;) on the subject of aviation airbags.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-20T21:54:51.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9820" PostTypeId="2" ParentId="9813" CreationDate="2014-11-20T22:43:28.500" Score="1" Body="&lt;p&gt;Insomuch as the aircraft is flying in ground effect, yes, it exerts a downward force on a runway or aircraft carrier before the wheels actually touch down.  This is not weight, per se, but it has the same effect on the runway/carrier.  This is true for fixed-wing aircraft and helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters are better known for having significant ground effect.  Indeed, if you see a helicopter flying or hovering over water, and the surface of the water is visibly disturbed by the rotor-wash (downward moving air from the rotor), the helicopter is flying in ground effect.  In which case, it's pretty easy to visualize.  One of the more difficult tasks in flying a helicopter over uneven terrain is the fact that you may be going in and out of ground effect as you cross the terrain.  This makes, at best, for a bumpy ride.  At worst, crossing a narrow chasm can cause you to go out of ground effect, drop significantly, and collide with the opposite side of the chasm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do a YouTube search for &quot;ekranoplan&quot; (Russian term) or &quot;Caspian Sea Monster&quot; (western term for the same thing).  This was a very large wing-in-ground effect vehicle the Soviets were developing during the Cold War.  The aircraft was amphibious, meaning it took off and landed on water.  Even when the aircraft is &quot;flying,&quot; off the surface of the water, the water underneath is visibly disturbed by it.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="2859" LastEditDate="2014-11-21T18:59:26.943" LastActivityDate="2014-11-21T18:59:26.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9821" PostTypeId="2" ParentId="9813" CreationDate="2014-11-20T23:28:41.487" Score="0" Body="&lt;p&gt;&lt;strong&gt;The weight of the carrier + airplane system begins to increase when the wheels touch and gradually reaches a maximum when the wings stop providing significant lift&lt;/strong&gt;. It should be obvious that when the plane is in the air, it has no effect on the weight of the carrier, and equally obvious that when the plane is at rest, the weight of the carrier + plane system is exactly the full weight of both vessels added together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane only puts a momentary twist into this action. The apparent weight of an airplane at touchdown is very small, and increases as the plane settles. This is also obvious if you watch the gear suspension depress during the roll out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can do an easy experiment to verify this. Slowly lower a weight onto a scale. The measured weight will increase gradually as the 'lift' provided by your hand decreases to zero. Lateral motion and air pressure and the fact that an airplane is &quot;self-lifting&quot; can really be ignored here.&lt;/p&gt;&#xA;" OwnerUserId="2554" LastActivityDate="2014-11-20T23:28:41.487" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="9822" PostTypeId="1" CreationDate="2014-11-21T03:05:36.993" Score="15" ViewCount="5804" Body="&lt;p&gt;Clement Ader invented in the late 1890s, a plane that looked like a bat. It had a steam engine. Witnesses said it went airborne at least once and recorded a distance just over 50 meters. The Wright brothers made their first controlled flight in 1903.&lt;/p&gt;&#xA;" OwnerUserId="4341" LastEditorUserId="354" LastEditDate="2014-11-21T12:55:13.470" LastActivityDate="2017-10-05T18:31:37.140" Title="Did Clement Ader make the first flight even before the Wright brothers?" Tags="&lt;aviation-history&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9823" PostTypeId="1" CreationDate="2014-11-21T03:13:48.217" Score="6" ViewCount="4611" Body="&lt;p&gt;It was developed by British Airways and Air France in the 1970s as the first supersonic passenger/civilian airplane.&lt;/p&gt;&#xA;" OwnerUserId="4341" LastEditorUserId="595" LastEditDate="2016-05-15T09:39:41.930" LastActivityDate="2018-11-28T14:49:37.650" Title="Why did Air France retire Concorde?" Tags="&lt;commercial-aviation&gt;&lt;aviation-history&gt;&lt;supersonic&gt;&lt;concorde&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ClosedDate="2014-11-24T13:44:29.760" ContentLicense="CC BY-SA 3.0" />
  <row Id="9824" PostTypeId="2" ParentId="9823" CreationDate="2014-11-21T03:17:57.443" Score="1" Body="&lt;p&gt;The Concorde did fly for several years, but it couldn't fly supersonic over land (as Steve pointed out, it was able, but not allowed due to concerns about the sound of the sonic boom) and it guzzled fuel. In the end, it wasn't economically viable.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2014-11-21T03:53:56.407" LastActivityDate="2014-11-21T03:53:56.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9827" PostTypeId="2" ParentId="9764" CreationDate="2014-11-21T03:23:28.140" Score="-12" Body="&lt;p&gt;A pilot must have a very good kinesthetic sense : his or her position in the air, in the space. When you have that natural quality; training helps but it is natural, it is much easier to have the same feeling for you plane. Early pilots did not have any kind of instrument and they crossed very long distances. Bleriot, the French pilot, went over he Channel in the 1920s. Some veteran pilots are more competent than now a days when some feel over confident in their electronic system. The pleasure of piloting is feeling safe and confident in its own abilities. Piloting is a vocation; you have to have natural predispositions for it. When you have them, you like the job. You are less stress. Kinesthesie is the senses of a human being measuring motion in space, so in the air too.&lt;/p&gt;&#xA;" OwnerUserId="4341" LastActivityDate="2014-11-21T03:23:28.140" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9828" PostTypeId="2" ParentId="9823" CreationDate="2014-11-21T03:29:10.223" Score="15" Body="&lt;p&gt;Ultimately the cost of flying the aircraft was more than the revenue that it generated.  The Concorde began a steady decline to retirement after the firey crash of Air France Flight 4590 which killed 113 people, and again suffered setback after September 11th, 2001.  Even with the best safety record in airline history, the crash combined with the terrorist attacks led to passenger fear and low sales. Airlines that operated the Concorde eventually lost money on most flights, and long term operations were simply not sustainable.  To make matters worse, it was very limited to which airports it could fly to in the US: JFK, IAD and DFW. The FAA was opposed to the Concorde for pollution, noise and fuel inefficiency concerns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;British Airways cites mostly political reasons for the ending of its Concorde program.  They claim that the Concorde would have remained profitable had Airbus retained the airplane.  However, there was also speculation that, due to the dwindling numbers of passengers, BA realized that it could make more money carrying passengers subsonically across the Atlantic.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="3945" LastEditDate="2014-11-21T18:39:03.793" LastActivityDate="2014-11-21T18:39:03.793" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9830" PostTypeId="1" CreationDate="2014-11-21T03:32:57.357" Score="1" ViewCount="870" Body="&lt;p&gt;In the 1930s Zeppelins used hydrogen as the lighter-than-air gas to fill the envelope and give the ship buoyancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of gas is used today?&lt;br&gt;&#xA;Is it still as flammable as the Hydrogen from airships of the 1930s?&lt;/p&gt;&#xA;" OwnerUserId="4341" LastEditorUserId="64" LastEditDate="2014-11-21T04:44:49.623" LastActivityDate="2015-09-30T21:26:30.557" Title="What gas is used in airships to give them buoyancy?" Tags="&lt;aircraft-design&gt;&lt;lighter-than-air&gt;&lt;airship&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9831" PostTypeId="2" ParentId="9786" CreationDate="2014-11-21T03:35:35.293" Score="-1" Body="&lt;p&gt;I never saw any since I am born. I am 47 years old. In a business section, you can have rotating seats; but usually it is two seats facing two other seats. In Air Force one, I saw some pictures where the President of The United States is seated at a desk; I would remove that for safety issue.&lt;/p&gt;&#xA;" OwnerUserId="4341" LastActivityDate="2014-11-21T03:35:35.293" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9832" PostTypeId="2" ParentId="9779" CreationDate="2014-11-21T03:38:50.003" Score="0" Body="&lt;p&gt;If the plane is up the carrier and something go wrong, both planes crash. The first test of the USA Space Shuttle were done with a carrier having the shuttle on its top; it was for wind tests. A carrier having a plane to drop of a plane to take off from a carrier was tries to reach space at lower cost, planned in the 1970s and the tests done in the 1980s. A model with reservoir was chosen instead.&lt;/p&gt;&#xA;" OwnerUserId="4341" LastActivityDate="2014-11-21T03:38:50.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9834" PostTypeId="2" ParentId="9822" CreationDate="2014-11-21T03:43:51.707" Score="33" Body="&lt;h3&gt;Lots of people flew before the Wright Brothers.  Some of them even survived!&lt;/h3&gt;&#xA;&lt;p&gt;The Wright Brothers are credited as &lt;em&gt;inventors of the airplane&lt;/em&gt; not because they flew, but because they were the first to take flight in a vehicle which:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lifted itself using its own power (which &lt;a href=&quot;http://en.wikipedia.org/wiki/Abbas_Ibn_Firnas#Aviation&quot; rel=&quot;noreferrer&quot;&gt;gliders&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Yuan_Huangtou&quot; rel=&quot;noreferrer&quot;&gt;kites&lt;/a&gt; did not)&lt;/li&gt;&#xA;&lt;li&gt;Was &lt;em&gt;aerodynamically controllable&lt;/em&gt; by the pilot (which Ader's aircraft was not)&lt;/li&gt;&#xA;&lt;li&gt;Remained in sustained flight, rather than &lt;a href=&quot;https://www.youtube.com/watch?v=CiDDBCEsD5I&quot; rel=&quot;noreferrer&quot;&gt;taking momentary flight&lt;/a&gt; before returning to Earth&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-21T03:50:15.193" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9836" PostTypeId="2" ParentId="9813" CreationDate="2014-11-21T04:21:24.880" Score="2" Body="&lt;p&gt;As other answers explain, it's not the weight that increases, because the mass does not increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there is a downward force that adds to the downward force of weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is caused by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_%28aerodynamics%29&quot; rel=&quot;nofollow&quot;&gt;ground effect&lt;/a&gt;, which leads to an increased pressure under the aircraft, if it is flying lower than roughly its wingspan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The added downward force is the force caused by the increased pressure over the area of carier surface. &lt;/p&gt;&#xA;" OwnerUserId="1875" LastActivityDate="2014-11-21T04:21:24.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9837" PostTypeId="2" ParentId="9830" CreationDate="2014-11-21T09:21:16.570" Score="7" Body="&lt;p&gt;There are only 2 &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting_gas&quot; rel=&quot;nofollow&quot;&gt;lifting gasses&lt;/a&gt; that are lighter than air and practical for airships;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Helium&quot; rel=&quot;nofollow&quot;&gt;helium&lt;/a&gt;: this is a noble gas which means it's inert. Safest option all around except that US has a monopoly on the production of it. That is also the reason Zeppelins didn't use it because of an embargo the US had at the time against the Germans.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Hydrogen&quot; rel=&quot;nofollow&quot;&gt;hydrogen&lt;/a&gt;: even more buoyant than helium but flammable. It is however easier to get by running a current through water or dropping some metals in an acid.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The third option for providing buoyancy is &lt;a href=&quot;http://en.wikipedia.org/wiki/Thermal_airship&quot; rel=&quot;nofollow&quot;&gt;heated air&lt;/a&gt;, this requires a heat source to counteract the loss of heat over time.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="64" LastEditDate="2014-11-21T14:21:52.443" LastActivityDate="2014-11-21T14:21:52.443" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9838" PostTypeId="2" ParentId="7491" CreationDate="2014-11-21T11:16:04.437" Score="-2" Body="&lt;p&gt;One of my PPL textbooks briefly discussed the origins of QNH. Unfortunately I can't for the life of me find the correct passage, so I am unable to reference this properly. But from memory:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It dates back to the early days of navigation when the main communication method was morse code through the radiotelegraph.  The aircraft, wanting the atmospheric  pressure for altimiter calibration, would basically ask the ground station &quot;I have a question - what is the atmospheric pressure at &lt;em&gt;normal height&lt;/em&gt;?&quot; The 'normal height' reference over time became the sea level reference that we use today. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, because this question was so frequently required - and therefore an awful lot to communicate through morse code - it was abbreviated. &quot;I have a question&quot; became Q, &quot;what is the pressure at normal height?&quot; became NH - the message transmitted therefore was simply QNH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume the other Q codes evolved in a similar manner. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2014-11-21T11:16:04.437" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9839" PostTypeId="2" ParentId="9822" CreationDate="2014-11-21T11:59:43.543" Score="11" Body="&lt;p&gt;In a way, he did. But he had little control about all axes. Derisory comments even suggested he only took to the air thanks to his bumpy runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there were plenty more before him. The first flying objects which anticipated the airplane were the models of &lt;a href=&quot;http://en.wikipedia.org/wiki/Alphonse_P%C3%A9naud&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alphonse Pénaud&lt;/a&gt;. He finished the &lt;a href=&quot;http://en.wikipedia.org/wiki/Alphonse_P%C3%A9naud#The_Planophore&quot; rel=&quot;nofollow noreferrer&quot;&gt;Planophore&lt;/a&gt; in 1871 and influenced all who came after him. Unfortunately, at his time there was no energy source to power a man-carrying aircraft, and his models used rubber bands for storing energy. Please note that he did not forget to add a vertical tail; his design did not need it - the tail-mounted propeller stabilized it well enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next big step was made by &lt;a href=&quot;http://en.wikipedia.org/wiki/Otto_Lilienthal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Otto Lilienthal&lt;/a&gt;, and again the lacking power source restricted him, in his case to man-carrying gliders. He saw the airplane as a piece of sporting equipment, like a racing bicycle, and priced them accordingly. He sold over a dozen of them to people all over the world. And he was the first to use systematic scientific research: He found out that a thick, blunt leading edge and wing camber help to improve L/D. The polar plot has its name from him. He experimented with carbon acid engines, but never used a propeller, flapping the wing tips of one of his designs instead. He also invented wing twisting long before the Wrights, and shared his results freely with the aviation pioneers of his time. The Wright Brothers built their success on the basis of his work, and were much more secretive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we mention Clement Ader, we also need to include &lt;a href=&quot;http://en.wikipedia.org/wiki/Hiram_Maxim&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hiram Maxim&lt;/a&gt; and maybe even &lt;a href=&quot;http://en.wikipedia.org/wiki/Samuel_Pierpont_Langley&quot; rel=&quot;nofollow noreferrer&quot;&gt;Samuel P. Langley&lt;/a&gt;. They (&lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_aviation_pioneers&quot; rel=&quot;nofollow noreferrer&quot;&gt;and a few more&lt;/a&gt;) all tried to create powered aircraft, but did not get it all right. At least, Langley's assistant &lt;a href=&quot;http://en.wikipedia.org/wiki/Charles_M._Manly&quot; rel=&quot;nofollow noreferrer&quot;&gt;Manly&lt;/a&gt; and S. Balzer gave the world the radial engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next pioneer would be Gustav Weißkopf (or &lt;a href=&quot;http://en.wikipedia.org/wiki/Gustave_Whitehead&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gustave Whitehead&lt;/a&gt;) who seemed to have flown a plane which took a lot of inspiration from Lilienthal's designs, but added a boat-like fuselage and wheels, so he had his hands free for steering the plane. Lilienthal had put himself into a tight corner by foot-launching his gliders and needing his hands to hold them. Whitehead flew in 1901, but discontinued his work to focus on his family. But he was the prime address of his time for airplane engines; many of the early pioneers bought his engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only now the &lt;a href=&quot;http://en.wikipedia.org/wiki/Wright_brothers&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wrights&lt;/a&gt; contributed their part, and are known as the inventors of the airplane due to a contract Orville made with the Smithsonian: The Smithsonian got the 1903 Flyer, but needs to present the Wrights as the sole inventors of the aircraft. Orville knew exactly how weak this claim was, so he insisted on this clause.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, in Europe, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Alberto_Santos-Dumont&quot; rel=&quot;nofollow noreferrer&quot;&gt;number&lt;/a&gt; of &lt;a href=&quot;http://en.wikipedia.org/wiki/Gabriel_Voisin&quot; rel=&quot;nofollow noreferrer&quot;&gt;pioneers&lt;/a&gt; achieved also &lt;a href=&quot;http://en.wikipedia.org/wiki/L%C3%A9on_Levavasseur&quot; rel=&quot;nofollow noreferrer&quot;&gt;powered&lt;/a&gt;, controlled flight without using the Wright's knowledge, because Orville and Wilbur kept their findings under tight wraps and started suing &lt;a href=&quot;http://en.wikipedia.org/wiki/Glenn_Curtiss&quot; rel=&quot;nofollow noreferrer&quot;&gt;everyone&lt;/a&gt; who would also attempt to take to the air. But at the Le Mans flight meeting of 1908 the Wrights showed off their more maneuverable design, shaming all European designers. How little lasting effect they had in the end becomes clear when you look at the &lt;a href=&quot;http://en.wikipedia.org/wiki/Bl%C3%A9riot_XI&quot; rel=&quot;nofollow noreferrer&quot;&gt;airplanes&lt;/a&gt; that &lt;a href=&quot;http://en.wikipedia.org/wiki/Deperdussin_1910_monoplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;followed&lt;/a&gt;: The inspiration clearly came from others.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-24T16:19:20.467" LastActivityDate="2014-11-24T16:19:20.467" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9840" PostTypeId="2" ParentId="9813" CreationDate="2014-11-21T12:10:54.603" Score="1" Body="&lt;p&gt;Everything depends on what you meant by &quot;weight&quot; in&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;aircraft landing on a carrier increase the carrier &lt;em&gt;weight&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Don't confound&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;mass&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;gravity force&lt;/em&gt; applied on a mass by the Earth&lt;/li&gt;&#xA;&lt;li&gt;and the &lt;em&gt;collection of forces components&lt;/em&gt; pointing down to the center of earth &lt;em&gt;including ground effect pressure&lt;/em&gt; (or induced air pressure produced by a fluid that has been moved &lt;em&gt;by another object&lt;/em&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;By the way, applying a downward pressure aft of a long floating thing will produce a momentum that induces lift on the front part of that thing (center of buoyancy) due to the &lt;em&gt;principle of flotation&lt;/em&gt; which involves displaced water equivalent to the total mass &lt;strong&gt;of the thing&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then comes a consideration about &lt;em&gt;thing&lt;/em&gt;, ie, what &lt;strong&gt;system&lt;/strong&gt; are you talking about ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft carrier is an object floating on the water while the aircraft is a moving object that exerts forces on anything in its vicinity including air, ground, whatever... until this aircraft landed, taxied out, applied parking brakes (and tied to the flight deck) At that moment, the aircraft can be assumed as non moving part of the boat and the system mass becomes boat mass + aircraft mass =&gt; defined new (and non moving) center of gravity with a new weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weight&lt;/strong&gt; is the force applied on an object due to &lt;strong&gt;gravity&lt;/strong&gt;. Assuming changes in mass, of the aircraft carrier as well as the aircraft can be neglected, and the two objects are close enough to have the same local gravitational magnitude, we can safely declare &lt;strong&gt;their weight doesn't change&lt;/strong&gt; whatever the aircraft is doing. The weight of the system [aircraft carrier + aircraft] is also constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what is changing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Everything but weight !&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pressure (fluids)&lt;/li&gt;&#xA;&lt;li&gt;Contact forces (impact, or much more complex at molecules level with moving air)&lt;/li&gt;&#xA;&lt;li&gt;Friction (induces momentum)&lt;/li&gt;&#xA;&lt;li&gt;Stress (at a neglectable scale, but exists anyway)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All this actually &lt;strong&gt;induce movement of the aircraft carrier&lt;/strong&gt; due to the landing plane before, during and after its landing. Whether that movement is neglectable or not only depends on your taste, but it does occur whatever you may think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In computing, just like trying to simulate a stellar system, even multithreading can't cope with continuously (analogic) varying forces simultaneously applied. But human brain can imagine it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everything becomes ultimately complex when you think of permanent oscillations, vibrations turbulences or viscosity. The models we are currently using doesn't allow you to get an exact answer allowing to know the precise vector defining the forces applied by a landing plane on a carrier. You can separate the logic in many small parts, but you'll always have to neglect one or several criterias to get as close as possible to what is &lt;em&gt;really&lt;/em&gt; happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Measure the submersion ?&lt;/em&gt;&lt;br /&gt;&#xA;Ocean is not still water. And air is compressible (high pressure/low pressure) Due to everything I said above, unless you know every parameter at any given time, you can't measure submersion... and at that scale...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try this :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a (precise and working) roberval balance, and a paper (A4). Hold the paper horizontally above one of the plates, like 6 or 8 inches above. Drop the paper. You'll notice the arrow telling the weight will move towards the plate on which the paper is landing, but will come back nearer to the center. Neither the weight of the paper or the balance has changed, but new forces came into action when you dropped the paper : Air pressure, contact forces, friction...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Want another example ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine a very wide window on your roof (to get a panoramic view of the sky at night) Then take an F14 or an F22 and make it fly supersonic some feets above your house... Weight ? No. Air pressure.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="3879" LastEditDate="2014-11-21T12:18:18.297" LastActivityDate="2014-11-21T12:18:18.297" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9842" PostTypeId="2" ParentId="9813" CreationDate="2014-11-21T13:42:32.360" Score="4" Body="&lt;p&gt;Actually, yes it does make it weight more, while the plane is still in the air, but over the carrier:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the force the plane actually exerts downwards on the carrier does not directly increase the carrier's weight, that same force does lower the carrier (minutely) in the water as it displaces slightly more water. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, since the carrier is now less far from the center of the planet, the force excerpted by gravity on the mass of the carrier is now (minutely) stronger, so the carrier weighs more.&lt;/p&gt;&#xA;" OwnerUserId="4349" LastEditorUserId="4349" LastEditDate="2014-11-21T16:41:37.283" LastActivityDate="2014-11-21T16:41:37.283" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9843" PostTypeId="2" ParentId="9823" CreationDate="2014-11-21T14:00:25.257" Score="6" Body="&lt;p&gt;&lt;strong&gt;Why did Air France retire the Concorde&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It wasn't making money - in fact, it was losing money. Huge fuel price increases shortly after it was brought in meant it was never really profitable for Air France. Then double-whammy of the Air France Flight 4590, followed a few years later by 9/11 hitting Airlines hard in reduced passenger numbers (particularly into New York), caused Air France to consider it no longer viable to run even as a loss-making flagship service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why did British Airways retire the Concorde&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A related but separate question, BA actually found a way to make their Concorde's profitable later on. They discovered that the public (particularly the business users who weren't paying for their own tickets...) thought Concorde tickets were more expensive than they actually were, so merely increased the price to match. They were profitable for several years until Airbus announced they were no longer going to maintain or support the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2018-11-28T14:49:37.650" LastActivityDate="2018-11-28T14:49:37.650" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9844" PostTypeId="1" AcceptedAnswerId="9902" CreationDate="2014-11-21T14:51:24.340" Score="3" ViewCount="408" Body="&lt;p&gt;Does anyone know what software is suitable to investigate air traffic flow capacities in various FIR's / routes. I need to see the effect of temporary reserved ares due to military activities, weather, changes of routing due to LOAs. Taking into account meteorological data would be advantage but it is not necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be great if it will be possible to emphesize (colours, histogram, ...). usage of FIR areas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of software tools are used by EUROCONTROL or ATM consultancy firms providing this service. What standard tools commercially available (or for free)?&lt;/p&gt;&#xA;" OwnerUserId="4110" LastEditorUserId="64" LastEditDate="2016-07-07T21:07:00.180" LastActivityDate="2016-07-07T21:07:00.180" Title="Where can I find an ATM simulation software to investigate traffic flow capacities?" Tags="&lt;air-traffic-control&gt;&lt;software&gt;&lt;atc-simulator&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="9845" PostTypeId="2" ParentId="3513" CreationDate="2014-11-21T15:33:36.813" Score="5" Body="&lt;p&gt;Fortunately this stereotype is changing, albeit slowly. Small GA engine development has been stuck in the back seat for generations and it's great to see a number of new start ups making the push towards change. The TP100 Turboprop by PBS is once such product. I really hope they reach their potential and bring the product to market, even if only to experimental parties. Continental is aggressively developing their new diesels and will be launching a new 230 ish hp unit in the next year. It is already in testing in China. If they get that right, it will be a Lycoming killer. They've already begun conversions with the 155 hp version in Cessnas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason the lower power (150-250 hp) turbines have not been developed more rapidly is that GA pilots have not pushed for them. They know they take more fuel, even if the power/weight ratio is far superior. The operating costs make them hide in the corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RR/Allison made an effort to refresh the aging 250 with a modern turbine that would appeal to the Cirrus crowd but bowed out when the 2008 financial crisis hit. The problem with companies like Allison is their development costs are through the roof. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Change in this space is going to require guts from the little ducks of the world. Many of which are now starting to appear on the scene. There is a well know shortage of 100LL around the world and soon here in the US. That and the high price of carting this boutique (not shipped in pipelines) fuel will fuel the market for these new products. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no rocket science at work here. It's old technology (albeit with a bit of electronic intervention) that just needs a market to grow in. Today we are moving towards that market. Get used to it and consider tossing that ole' Lyc.&lt;/p&gt;&#xA;" OwnerUserId="4352" LastActivityDate="2014-11-21T15:33:36.813" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9847" PostTypeId="1" AcceptedAnswerId="9849" CreationDate="2014-11-21T18:08:40.970" Score="3" ViewCount="28930" Body="&lt;p&gt;Let's say a plane is going to crash and all people on board know this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why can't they jump from the aircraft when the plane is near the ground?&lt;br&gt;&#xA;They would have higher chances of surviving, right?&lt;/p&gt;&#xA;" OwnerUserId="4354" LastEditorUserId="64" LastEditDate="2014-11-21T18:39:47.857" LastActivityDate="2014-11-21T22:07:29.150" Title="Can you jump out of a crashing plane just before impact to improve your chance of surviving?" Tags="&lt;flight-planning&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2014-11-22T03:45:27.553" ContentLicense="CC BY-SA 3.0" />
  <row Id="9848" PostTypeId="2" ParentId="8674" CreationDate="2014-11-21T18:13:18.330" Score="7" Body="&lt;p&gt;SR71 crew would heat their meals by pressing them against the windows, as they were hot enough to burn fingers if the glass was touched. The crew would then eat with the helmet open. The SR71 was pressurized not for crew comfort, but rather to cool the electronics!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter pilots, like the Mercury and Gemini missions, wear adult diapers in flight. As the joke goes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What does the inside of an EVA suit smell like?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;‏&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.depend.com/&quot; rel=&quot;noreferrer&quot;&gt;&quot;Depends.&quot;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I believe that it was Alan Shepard who famously ruined some on-board electronics when his pee shorted them out.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="354" LastEditDate="2014-11-21T22:21:46.183" LastActivityDate="2014-11-21T22:21:46.183" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9849" PostTypeId="2" ParentId="9847" CreationDate="2014-11-21T18:37:49.610" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why can't they jump from it when the plane almost reaches the ground?&lt;br&gt;&#xA;  They would have higher chances of surviving, right?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember your body still has roughly the same momentum it did when it was in the vehicle - just because you jumped out doesn't mean you're not still moving forward at a rate of speed the human body simply isn't designed for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's reframe your question: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you were in a car doing 60 miles per hour and you knew the car was about to crash into a brick wall, would you jump from the vehicle, or would you remain strapped into your seat where the car, seat, seatbelt, and airbag will all help absorb the impact?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As with a car, being inside an aircraft and properly restrained will afford you substantial protection from the initial impact, and some of the crash energy will be absorbed damaging the aircraft. That increases the length of time it takes to decelerate your body and gives you a better chance of survival.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you jumped out of your friend's Cessna because it's going down and might hit some trees your unrestrained body would be decelerated far more abruptly when &lt;em&gt;you&lt;/em&gt; hit the trees (or the ground).&lt;br&gt;&#xA;You might survive, but you've lessened your chances considerably (and the Cessna is a best-case scenario - your forward speed would be around 60mph as in the car example. For something like a 747 you'd be in the 150 mile-per-hour range or faster when you jumped out, which is almost certainly not survivable).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-21T18:37:49.610" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9850" PostTypeId="2" ParentId="8674" CreationDate="2014-11-21T19:52:48.517" Score="5" Body="&lt;p&gt;Piddle packs are used.  I've never used one so I can't say how tough they are to use.  For food and drink just bring whatever you want.  I usually keep a water bottle in my helmet bag but I know guys bring the AFE issued canteens and stick them in the lower pockets of their G-suit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did hear a story once of an old IP at my squadron that reached the EOR and had to piss.  So he unstrapped and pissed over the canopy rail. I'm sure it happens more than I know though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also you can remove the mask to eat and drink.  However in today's fighters you're breathing under pressure with a system called Combat Edge.  In addition you can't be heard well if the mask is hanging.  Or if you're hot mic, it annoys the other cockpit.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorDisplayName="user3309" LastEditDate="2014-11-21T20:03:20.590" LastActivityDate="2014-11-21T20:03:20.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9851" PostTypeId="2" ParentId="9847" CreationDate="2014-11-21T22:07:29.150" Score="3" Body="&lt;p&gt;No, jumping out of a plane just before it crashes wouldn't help you, for the same reasons that &lt;a href=&quot;https://physics.stackexchange.com/q/214/40456&quot;&gt;jumping off the floor in a free-falling elevator wouldn't help you&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2014-11-21T22:07:29.150" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9852" PostTypeId="2" ParentId="8674" CreationDate="2014-11-22T01:52:42.317" Score="69" Body="&lt;h2&gt;Life Strapped to the Rocket&lt;/h2&gt;&#xA;&#xA;&lt;h2&gt;Food and Drink&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Fighter pilots do not have any problem taking food and drinks on flights.  The biggest concern is to prevent &lt;a href=&quot;http://en.wikipedia.org/wiki/Foreign_object_damage&quot;&gt;foreign object damage&lt;/a&gt; (FOD) from items like crumbs, bottles, bags, etc.  Otherwise, there are plenty of places to carry food to eat: your helmet bag, G-Suit pockets and flight suit pockets.  I typically carry water with me in my g-suit pocket, and don't worry about food unless its going to be a long flight.  Thankfully, training missions are rarely long enough that they require food in the cockpit, and it mostly just applies to deployments.  Typical food usually includes protein bars, chocolate, cereal bars, etc.  We try to avoid small loose foods like peanuts and M&amp;amp;M's because they could easily spill and FOD the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on cockpit altitude, the mask can be easily removed to either eat or drink.  However, fighter cockpits are only partially pressurized, and, in the Super Hornet, there are times when cockpit altitude can be as high as 20,000ft.  Sound judgement is required before removing your mask.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I've also seen guys incorporate camelpacks into their harness/vests as well.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Restroom&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Obviously life on board a fighter jet is cramped, and there isn't a lot of room to move your body, much less use the restroom.  In addition to water, on every flight I carry an item called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Urine_collection_device&quot;&gt;pittle pack&lt;/a&gt;.  As its been stated, its a plastic bag with powder in it that reacts to urine.  The powder and urine mixture then turns to a jelly that helps prevent spillage, and the entire bag then rolls down and seals on itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pittle packs present 2 major problems (three for carrier pilots):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First: Where the hell do I put this bag of urine?&lt;/strong&gt; There isn't a lot of storage space on fighter aircraft and nobody wants to put a bag of urine in their g-suit pocket or helmet bag.  Sometimes you can get away with placing the bags in the flight publication pockets, but you better be sure it doesn't fall out.  The last thing you want is for the bag to fall, break, and then to smear about the cockpit as you continue with your mission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second: How do I get my junk out of this rocket powered chastity belt?&lt;/strong&gt; My harness is strapped tightly 8 ways to the ejection seat, which is also cinched tightly to my g-suit.  My g-suit has an opening for my crotch, but its tightly zipped into position over my flight suit.  My flight suit has a zipper, but as stated, the zipper is covered by the g-suit.  And just to add one last layer of difficultly to this impenetrable force field, I've got to dig myself out from between the folds of my boxer briefs.  Success! I've managed to free myself only to discover that the tip of my business end is only barely protruding from this labyrinth of zippers and belts (size may not matter in the bedroom, but it sure as hell matters right now).  The next question you have to ask yourself is, do I have enough time to keep digging, or do I need to attempt to arc it into the bag?  Choose wisely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third (The carrier pilot):  Boom, OK three-wire trap!&lt;/strong&gt;  Ah , the Naval Aviator.  I drop bombs, piss in bags, and then return home to land on a boat.  I'm pretty much a boss... and I'm covered in piss because I didn't secure my pittle pack before trapping on the boat.  The bag, upon catching the three-wire, like a boss, rocketed across the cockpit and smashed against the bulkhead, exploding all over my legs.  Always remember to secure your pittle packs before trapping on the boat, because even if your buddies didn't see it happen, you can guarantee the ground crew will tell them all about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our female counterparts are forced to wear &lt;a href=&quot;http://en.wikipedia.org/wiki/Depend_%28undergarment%29&quot;&gt;depends&lt;/a&gt;, I don't envy them at all.  Brave souls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oh, and if its not pee, RIP.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="65" LastEditDate="2015-02-12T19:25:58.497" LastActivityDate="2015-02-12T19:25:58.497" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9853" PostTypeId="2" ParentId="9789" CreationDate="2014-11-22T06:02:54.127" Score="0" Body="&lt;p&gt;I think the biggest component of the difference is the surmised answer, that is the wings are not level in the described situation. If wing is strong enough, you will have to transition to rolling on one, upwind wheel, or you will not be able to keep on the centerline.&lt;/p&gt;&#xA;" OwnerUserId="3982" LastActivityDate="2014-11-22T06:02:54.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9854" PostTypeId="1" AcceptedAnswerId="9855" CreationDate="2014-11-22T14:18:20.327" Score="30" ViewCount="5547" Body="&lt;p&gt;Imagine this scenario:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A modified military 747 is flying at a constant speed and altitude. On the top of the fuselage there is a device like a helipad but with three holes to accommodate the fighter jet landing gear, when pressure is applied the holes close, locking the landing gear in the holes. The fighter is flying at the same speed and slightly above. With proper training, is it possible for the pilot to land on the plane and then shut off the engines?&lt;/p&gt;&#xA;" OwnerUserId="3493" LastEditorUserId="1696" LastEditDate="2018-04-26T19:46:35.063" LastActivityDate="2018-04-26T19:46:35.063" Title="Can a fighter jet land on a modified airliner?" Tags="&lt;airliner&gt;&lt;landing&gt;&lt;flight-training&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9855" PostTypeId="2" ParentId="9854" CreationDate="2014-11-22T15:24:57.357" Score="42" Body="&lt;p&gt;Technically yes. But I am unaware of any attempt to do this with airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there were &lt;a href=&quot;http://en.wikipedia.org/wiki/Parasite_aircraft&quot; rel=&quot;noreferrer&quot;&gt;several designs&lt;/a&gt; in the past which used a big airplane or a &lt;a href=&quot;http://en.wikipedia.org/wiki/USS_Macon_(ZRS-5)#mediaviewer/File:F9C-2_Sparrowhawk_fighter.jpg&quot; rel=&quot;noreferrer&quot;&gt;Zeppelin&lt;/a&gt; as a mother ship, which took fighters with it for air defense. The &lt;a href=&quot;http://www.nationalmuseum.af.mil/shared/media/photodb/photos/050324-F-1234P-011.jpg&quot; rel=&quot;noreferrer&quot;&gt;B-36&lt;/a&gt; was involved in several such designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2n1IR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases the docking was made from below, because this gave the fighter pilot the best field of view and reduced the risk of a tail strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the fighter in the picture above is a Republic F-84, McDonnell even designed one specifically for the purpose of being carried around by a bomber, the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_XF-85_Goblin&quot; rel=&quot;noreferrer&quot;&gt;XF-85 Goblin&lt;/a&gt;. It used a rather complicated trapeze for docking and was then pulled up into the fuselage, as the picture with a B-29 below shows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EFUMl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your design proposal with the simple platform on top of the fuselage would carry a high risk of a tail strike if anything goes wrong, so it is unlikely that this will ever be tried for real. But when you change the airliner to a AN-225, the idea looks not totally impossible. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Zveno_project&quot; rel=&quot;noreferrer&quot;&gt;Russians tried to dock a fighter&lt;/a&gt; with a mothership as early as the 1930s. The picture below shows a TB-3 docking with a I-Z fighter, the first pair of aircraft in history to dock in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qcGq8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason for docking was the much smaller range of fighters. Today, air refuelling takes care of this deficit, so it is unlikely that anyone will see a benefit strong enough to justify the expense of modifying two aircraft and the risk incurred in the docking process.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1309" LastEditDate="2014-11-22T19:43:05.500" LastActivityDate="2014-11-22T19:43:05.500" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9856" PostTypeId="2" ParentId="9854" CreationDate="2014-11-22T15:25:22.103" Score="10" Body="&lt;p&gt;Parasite jet aircraft have been experimented with, the only purpose built one I know of is the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_XF-85_Goblin&quot;&gt;XF-85 Goblin&lt;/a&gt;, there was also a modified F-84 Thunderjet which was used as well. These experiments were abandoned because the process of launching and recovery was too hazardous, and air to air refueling made much more sense to extend the range of fighters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to join 2 aircraft in the manner you describe, however it's extremely dangerous due to the aerodynamic forces involved, and there are no benefits which would make the risks worthwhile. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-11-22T15:25:22.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9857" PostTypeId="2" ParentId="8914" CreationDate="2014-11-22T15:27:34.293" Score="16" Body="&lt;p&gt;There is a second very important consideration for the shape &amp;amp; size of rotor blades: how they behave during an autorotation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can think of two factors relating to autorotation in blade design: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;the ability of the blades to be driven by airflow up through the blades (the &quot;driven&quot; region of the blade in photo &lt;a href=&quot;https://i.stack.imgur.com/mEmVd.jpg&quot;&gt;2&lt;/a&gt;), while at the same time generating lift (the &quot;driving&quot; region of the blade): &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The amount of inertia stored in the rotating blades which can be expended in the flare by pulling up on the collective to cushion the landing. Small rotors (or group of them, such as in a quadcopter), just don't have enough inertia to nearly eliminate vertical motion in the autorotation flare.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Chapter 11 of the FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch11.pdf&quot;&gt;Helicopter Flying Handbook&lt;/a&gt; describes heli flight in autorotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mEmVd.jpg&quot; alt=&quot;driven by air flow up through the blades&quot;&gt;&#xA; &lt;img src=&quot;https://i.stack.imgur.com/CNZ9f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-11-22T15:27:34.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9858" PostTypeId="2" ParentId="9854" CreationDate="2014-11-22T19:24:39.423" Score="4" Body="&lt;p&gt;It is not possible to replicate this process safely.  The pilot in the smaller aircraft can not see its gear and would have no idea where to  &quot;land&quot;.  And perhaps even more importantly, there's no out if the fighter has an emergency.  If the fighter loses control just above the carrier then its likely that both aircrews will die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has been pointed out in other posts, aircraft have been recovered underneath carrier airplanes in the past, and while dangerous, this leaves an obvious escape route in the event of an emergency.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2014-11-22T19:24:39.423" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9859" PostTypeId="2" ParentId="9854" CreationDate="2014-11-22T20:32:58.893" Score="2" Body="&lt;p&gt;DARPA just happens to be &lt;a href=&quot;http://www.governmentsecrets.com/wanted-ideas-transforming-planes-aircraft-carriers-sky/&quot; rel=&quot;nofollow&quot;&gt;asking for proposals&lt;/a&gt; on how to accomplish this very task:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DARPA invites input on how to enable existing large aircraft to carry,&#xA;  launch and recover multiple unmanned air systems for a variety of&#xA;  missions&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4359" LastEditorUserId="3887" LastEditDate="2014-11-23T18:11:47.480" LastActivityDate="2014-11-23T18:11:47.480" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="9860" PostTypeId="1" AcceptedAnswerId="9864" CreationDate="2014-11-22T22:37:24.597" Score="21" ViewCount="5563" Body="&lt;p&gt;There is &lt;a href=&quot;https://aviation.stackexchange.com/questions/3815/why-have-cargo-hybrid-airships-not-succeeded-in-the-market&quot;&gt;this&lt;/a&gt; question but I am hoping for more general answers to why airships are not more commonplace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The previous question does bring up the cost of production (mainly because of hi-tech fibers used in body construction) and the high capital costs for constructing hangars for these airships. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, civilization did operate fleets of these before and I'm just not certain why they have not 'come back' in a meaningful way. For instance, here are just a few uses that I can think of off-hand:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For tourism! Instead of a water-bourne cruise tourists can literally sail all over (I'd pay for that!)...&lt;/li&gt;&#xA;&lt;li&gt;As the previous question implied, they can be used to carry cargo vast distances (although I am unsure if there is any real economic advantage here).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I know we use them in a small way for various things (military, sports, etc) but why are they not more commonplace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine the answer is mere economics but at the same time I feel there should be a market if for nothing else than tourism.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;No one has really touched on the possibility of a cruise ship style airship. We have mentioned brief aerial tours but I'm talking about a semi-luxury week long trip in one of these things over very remote areas such as Alaska or the Siberia or even a desert... I realise there would not be room for all the luxuries of a cruise ship (pool, casino, etc) but I image about the same luxuries as a small yacht...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine there are a lot of issues with long trips but can airships make unimproved 'port calls'? IE can they just set down for a few hours to let the passengers stretch their legs?&lt;/p&gt;&#xA;" OwnerUserId="3699" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2020-07-30T11:39:29.803" Title="Why are airships not more popular?" Tags="&lt;aviation-history&gt;&lt;airship&gt;" AnswerCount="9" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9861" PostTypeId="2" ParentId="9860" CreationDate="2014-11-22T23:19:42.513" Score="9" Body="&lt;p&gt;In the time of the zeppelin, long range travel was for the wealthy and going across the ocean was an adventure in and of itself. People didn't care that much about speed because the only other option was a ship that took weeks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For cargo, the container ship is much more economical simply because it can take so much more in one go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Emma_M%C3%A6rsk&quot; rel=&quot;nofollow&quot;&gt;Emma Maersk&lt;/a&gt; container ship can take up to 11000 twenty foot containers around the Eurasian continent. She roundtrips between Rotterdam and Hong Kong at a max speed of 47 km/h.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="3386" LastEditDate="2015-04-12T10:19:58.467" LastActivityDate="2015-04-12T10:19:58.467" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9862" PostTypeId="2" ParentId="9860" CreationDate="2014-11-23T00:07:31.377" Score="3" Body="&lt;p&gt;For cargo, they're a non-starter. They have &lt;em&gt;much&lt;/em&gt; lower capacity than ships and presumably aren't any faster. We already have huge amounts of infrastructure for the shipping industry and would need to build it all again for airships.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe they'd work for tourism. You'd imagine that somebody would already be doing it if there were money in it but, of course, somebody has to be first.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-11-23T00:07:31.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9864" PostTypeId="2" ParentId="9860" CreationDate="2014-11-23T09:13:53.943" Score="18" Body="&lt;p&gt;Airships are much more susceptible to bad weather. With an airplane you can pretty much count on it taking off on time and arriving within a couple of minutes of the scheduled time. This allows operators to employ their aircraft with a reliability which an airship will never be capable of. This means that the investment made into an airliner will lead to a predictable stream of revenue and (hopefully) profit, whereas the airship might need to wait several days until it can take off again, or headwind  might delay it by more than a day on a long trip. In this time, it will accumulate interest and fixed cost, but no additional revenue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scheduled air services were indeed &lt;a href=&quot;http://en.wikipedia.org/wiki/DELAG&quot; rel=&quot;noreferrer&quot;&gt;first done with airships&lt;/a&gt;, but as soon as &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_F.13&quot; rel=&quot;noreferrer&quot;&gt;dependable aircraft&lt;/a&gt; were available, only a few niches like transatlantic travel were operated with airships. As soon as airplane performance covered those niches, airships became obsolete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today the most credible use of airships would be transportation of heavy equipment into remote areas. Tourism could be a second use, but the number of airships needed to cover this market is small. Airships do have some benefits:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;no need to build roads or runways&lt;/li&gt;&#xA;&lt;li&gt;carrying of outsize cargo is no problem&lt;/li&gt;&#xA;&lt;li&gt;if the airship is big enough, payload can be immense&lt;/li&gt;&#xA;&lt;li&gt;destinations can be anywhere, not only on a coast or a big river (where regular ships cover this niche more than adequately)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The few cases where the airship could be employed gainfully would not cover the expense of developing and building one. Development cost alone would be similar to the development cost of a new airliner!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if we look back in history, even at a time when airships were available, big transportation tasks were done by aircraft. Papua has impenetrable jungles, and to &lt;a href=&quot;http://www.mra.gov.pg/en-us/geologymining/mininghistory.aspx&quot; rel=&quot;noreferrer&quot;&gt;transport dredging equipment and personnel to the Morobe goldfield&lt;/a&gt; from 1932 on, aircraft were used rather than airships. The huge &lt;a href=&quot;http://en.wikipedia.org/wiki/Dredging&quot; rel=&quot;noreferrer&quot;&gt;dredges&lt;/a&gt; were dismantled for air transport and flown into Bulolo, where they were re-assembled and put to work. With a Zeppelin, less dismantling would have been needed, but just the complication of keeping the airship balanced when the load is released made this option less attractive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the history buffs: To transport very long items like the dredge shafts, a single-engined Junkers Ju-52 (&lt;a href=&quot;http://de.wikipedia.org/wiki/Junkers_Ju_52/1m&quot; rel=&quot;noreferrer&quot;&gt;Ju-52/1m&lt;/a&gt;) was used. It had a detachable rear fuselage with  automatic couplings for the control rods. Spherical collar screws ensured precise positioning of the two fuselage sections.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-15T20:10:33.163" LastActivityDate="2015-06-15T20:10:33.163" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9865" PostTypeId="1" CreationDate="2014-11-23T13:08:16.133" Score="6" ViewCount="924" Body="&lt;p&gt;I’d like to build one that is heavier than a F3J plane and it will be similar to NASA’s soaring plane of the &quot;Autonomous Soaring Plane&quot; project. What kind of airfoil do I need? Simply scaling a normal airfoil would have bad results.&lt;/p&gt;&#xA;" OwnerUserId="4363" LastEditorUserId="946" LastEditDate="2014-11-23T18:03:23.343" LastActivityDate="2016-03-28T20:19:53.433" Title="What airfoil design is needed for a 4 m wingspan soaring plane?" Tags="&lt;aerodynamics&gt;&lt;model-aircraft&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9866" PostTypeId="2" ParentId="2572" CreationDate="2014-11-23T14:21:58.637" Score="7" Body="&lt;p&gt;You state that &quot;the transition should be much simpler in terms of human factors.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, yes.  In practice, no.  When mistakes happen, they may well be lethal.  The  Gimli Glider incident was partly caused by a confusion between which system was used to measure fuel quantity.  From &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The subsequent investigation revealed a combination of company failures and a chain of human errors that defeated built-in safeguards. Fuel loading was miscalculated due to a misunderstanding of the recently adopted metric system which replaced the imperial system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The fact that the Gimli Glider incident ended with no loss of life doesn't negate my point: Human factors such as fatigue will find a way to defeat the best plans of the Safety Engineers.  One of the human factors of which you speak is &quot;what you learned first, you learned best&quot; — and this learning is likely to predominate in an emergency situation.&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="1696" LastEditDate="2015-02-13T00:28:44.127" LastActivityDate="2015-02-13T00:28:44.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9867" PostTypeId="2" ParentId="9764" CreationDate="2014-11-23T16:32:39.363" Score="2" Body="&lt;p&gt;The airport I learned to fly at was the home of many planes.  On Friday afternoon / evening during the summer the people would fly their planes to the beach, a couple of hours east of the airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One Friday afternoon while I was learning I was practicing touch-and-go's.  I knew that my time was limited because there was a storm south of the airport, about an hour away.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For about thirty minutes I had the airport to myself, but then some of the earlier departures to the beach started returning.  Next thing you know the airport has a lot of planes in the pattern.  And of course I am last!  I never lost sight of the ground but the thunderstorm I was in scared me beyond believe.  (At one point I even considered landing at Andrews AFB that I could see and was in sunshine)  My instructor got on the radio and eventually talked me through it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several weeks later while doing my long cross country I got a weather report indicating a thunderstorm ahead of me.  Several minutes earlier I had passed over the airport at Orange, VA.  Half an hour after landing at Orange, VA the thunderstorm hit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GA pilots that test mother nature are a fatality waiting to happen.&lt;/p&gt;&#xA;" OwnerUserId="1651" LastActivityDate="2014-11-23T16:32:39.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9868" PostTypeId="2" ParentId="9865" CreationDate="2014-11-23T17:39:54.307" Score="7" Body="&lt;p&gt;First for those who wonder what F3J is: This is the &lt;a href=&quot;http://en.wikipedia.org/wiki/F%C3%A9d%C3%A9ration_A%C3%A9ronautique_Internationale&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAI&lt;/a&gt; model aircraft category for thermal soaring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quick answer: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9682/data-tables-for-lift-and-drag-coefficients/9684#9684&quot;&gt;This answer&lt;/a&gt; describes what resources are available on the Net.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your choice of airfoil depends on the wing loading and the size of the model, because those will determine the &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds number&lt;/a&gt; of the flow over the wings. Soaring flight requires high lift coefficients, but maybe you also want low drag for sprints between thermals or to avoid being blown away by strong winds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070022339.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;description&lt;/a&gt; of the NASA Autonomous Soaring Plane gives 15 pounds of mass and a wingspan of 170 in. It was based on a model glider by &lt;a href=&quot;http://www.rnrproducts.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;RnR Products&lt;/a&gt;, and there I found the aspect ratio of 19.8 and the wing area of 1545 sq.in. These numbers are not very consistent, but close enough to get an idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thermals are strongest in their center, so it is desirable to fly as tight a circle as possible. Low wing loading $\frac{m}{S}$ and a high lift coefficient $c_{l_{max}}$ drive the minimum turning radius $r_{min}$ down (at a given density of air $\rho$), and the formula is:&#xA;$$r_{min} = \frac{\frac{n_{z_{max}}}{\sqrt{n_{z_{max}}^2 - 1}}}{c_{l_{max}}\cdot\frac{\rho}{2}\cdot \frac{S}{m}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here $n_{z_{max}}$ is the maximum load factor, and the picture below shows that little is gained by increasing $n_{z_{max}}$ beyond 3. The little &lt;a href=&quot;http://en.wikipedia.org/wiki/DFS_Habicht&quot; rel=&quot;nofollow noreferrer&quot;&gt;DFS Habicht&lt;/a&gt;s help to illustrate the bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fy1kg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a wing loading of 6.8 $kg/m^2$ and a mean wing chord of just 23 cm the flight speed at a $c_l$ of 1.2 is 9.5 m/s. At sea level in a standard atmosphere the Reynolds number would be 150,000. The wingtip flies at a Reynolds number of below 100,000. In circling flight with a bank angle of 60° (equivalent to 2g, so you need twice the lift), the Reynolds number would increase to 212,000 for the mean chord and to 140,000 for the tip. If this sounds a lot to you, it isn't. This is a flow which needs highly specialized airfoils. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My recommendation is to try the &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/coord_database.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;UIUC airfoil database&lt;/a&gt; and select a specific model airfoil with low drag at high lift coefficients and &lt;a href=&quot;http://m-selig.ae.illinois.edu/uiuc_lsat.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds numbers down to 100.000&lt;/a&gt;. It should have high camber and a thickness of around 12% to keep wing weight down. If you have the lower range of Reynolds numbers covered, you need not to worry about the higher range. You might even consider to use different airfoils over the wingspan, depending on the minimum local Reynolds number. Ideally, you'll find a set of airfoils which have been optimized for exactly this purpose, like the DAE11 - DAE21 - DAE31 airfoils of the &lt;a href=&quot;http://en.wikipedia.org/wiki/MIT_Daedalus&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dedalus human powered aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-11-24T06:16:40.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9869" PostTypeId="1" AcceptedAnswerId="9870" CreationDate="2014-11-23T20:37:58.447" Score="27" ViewCount="2786" Body="&lt;p&gt;I want to make the most of my time and budget. There are ton of flight instructors and the quality has to vary widely. Besides being a competent pilot, what should I look for in a CFI? What are the warning signs of a poor CFI?&lt;/p&gt;&#xA;" OwnerUserId="4364" LastEditorUserId="65" LastEditDate="2015-01-13T22:28:32.637" LastActivityDate="2020-01-01T20:14:42.793" Title="What to look for in a flight instructor?" Tags="&lt;flight-training&gt;&lt;student-pilot&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9870" PostTypeId="2" ParentId="9869" CreationDate="2014-11-23T23:48:20.140" Score="18" Body="&lt;p&gt;This is an excellent question and at the same time, very broad. Every student and pilot can give you a ton of advice about what qualities the best &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_instructor&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFI&lt;/a&gt; must have. I will list a few qualities to look for and then guide you to a few resources which can further elaborate the topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume you are going for Part 61 (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=43480f59479f9a1019f8298ad787a84e&amp;amp;node=14:2.0.1.1.2.7.1.7&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14CFR61.159&lt;/a&gt;). I also presume that you have selected a flight school or will choose from a few around your.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you get to a flight school, normally you will be assigned a CFI by them. They will interview you and you should do the same.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Ask the CFI why they are teaching and what their goals are&lt;/strong&gt;&lt;br&gt;&#xA;Generally speaking, one half of CFIs are doing it for their future career goals (i.e. to get a job in an airline) and others are doing just because they earned the CFI rating and hence are earning money by teaching.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Once you start flying with a CFI, see how they respond to your mistakes&lt;/strong&gt;&lt;br&gt;&#xA;You are a student and are learning something new. There is no way that you will master everything taught just once. (Maybe you can, I'm not just that smart.) Observe how the CFI will notice your mistake, bring it your attention, rectifies it themselves or gives you instructions to do it, and most importantly, how your mistake affects their mood?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Before and after each lesson, notice how they answer your questions and explain to you what you guys will be doing and have done&lt;/strong&gt;&lt;br&gt;&#xA;Some people (like me) would ask a million questions. Often times, you will find teachers/instructors who don't like to be questioned a lot. All your questions are genuine, you just need to see how they are answered.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Ask your pilot friends to guide you, or check with other students at your flight school.&lt;/strong&gt;&lt;br&gt;&#xA;Your friends can give you a very honest feedback. You can benefit from other students too, but if a CFI works for someone else, they may not work for you. You are the one to judge and make the call.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Naturally, you cannot know about a CFI's style unless you take a few lessons with them. That will definitely cost you money. But spending a little money to learn a valuable lesson is not &lt;em&gt;wasting&lt;/em&gt; money. It is an investment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not talking about some other details as they are discussed thoroughly in the references below.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here are some resources which have answered this same question in more detail.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.pilottricks.com/how-to-choose-a-flight-instructor/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot Tricks&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.askacfi.com/1536/how-do-i-select-a-flight-instructor.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ask A Flight Instructor&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.wikihow.com/Choose-a-Flight-Instructor&quot; rel=&quot;nofollow noreferrer&quot;&gt;wiki How&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aopa.org/letsgoflying/ready/choose/howto.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA&lt;/a&gt; &lt;em&gt;(AOPA has an article about almost everything aviation-related)&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://aviation.about.com/od/Pilot-Training/tp/How-to-Choose-a-Flight-Instructor.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;About Money&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.flyingmag.com/training/learn-fly/flight-school-finding-right-instructor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flying Mag&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="13197" LastEditDate="2020-01-01T20:14:42.793" LastActivityDate="2020-01-01T20:14:42.793" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9871" PostTypeId="2" ParentId="9771" CreationDate="2014-11-24T00:18:57.990" Score="6" Body="&lt;p&gt;I worked at a general aviation airport for 10 years. At that one, security consisted of three strands of barbed wire around the perimeter and a chain across the gate. The priority was keeping cows off the runway. The police (and fire) were 30 minutes away, and that's assuming the payphone works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The paved runway could handle any propeller plane and light jets like a Citation or smaller Gulfstream. You could load them up with absolutely anything and anyone you wanted, and nobody would know about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger airports in the area did have manned security, although their concern was theft and vandalism rather than contraband.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="753" LastEditDate="2017-08-22T12:13:34.980" LastActivityDate="2017-08-22T12:13:34.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9872" PostTypeId="1" AcceptedAnswerId="9876" CreationDate="2014-11-24T04:43:41.637" Score="20" ViewCount="6539" Body="&lt;p&gt;There are other questions (c.f. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9830/what-gas-is-used-in-airships-to-give-them-buoyancy&quot;&gt;What gas is used in airships to give them buoyancy?&lt;/a&gt;) that discuss the use of lifting gasses such as Helium and Hydrogen in airships. Helium is rare and Hydrogen is flammable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one could build a light-enough and strong-enough rigid outer frame, then couldn't one use a vacuum rather than lifting gasses?  At ground level, the frame would only have to withstand 15psi (100,000 pascals), which isn't a tremendous amount of force. Theoretically, a vacuum should provide even greater lifting force than any gas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have there been any attempts at vacuum based rigid-dirigibles -- and if not, what are the technical or mechanical limitations to doing so?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2014-11-30T04:03:11.033" Title="Could I build an airship (rigid dirigible) that used a vacuum rather than lifting gas?" Tags="&lt;aircraft-design&gt;&lt;lighter-than-air&gt;&lt;airship&gt;" AnswerCount="5" CommentCount="11" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9873" PostTypeId="1" AcceptedAnswerId="9881" CreationDate="2014-11-24T06:41:26.610" Score="13" ViewCount="4380" Body="&lt;p&gt;The single-engine Cessna 172 and 182 aircraft models have a dual gravity-fed fuel system, where you can draw from both the LH and RH tank simultaneously in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard it said that when you are securing the airplane after a flight to leave the tank selector on the RH tank to prevent crossflow if the ramp is uneven. (So you don't end up with all the fuel in one tank).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any merit to this?  Does it actually block the crossflow valve to do this?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="132" LastEditDate="2016-05-13T21:27:38.117" LastActivityDate="2018-08-20T06:14:24.733" Title="Cessna 172/182: Should I set the tank selector to the R.H. tank after parking the airplane?" Tags="&lt;ground-operations&gt;&lt;fuel-tanks&gt;&lt;cessna-172&gt;&lt;cessna-182&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9874" PostTypeId="2" ParentId="9860" CreationDate="2014-11-24T08:27:09.907" Score="9" Body="&lt;p&gt;First let's compare some numbers. &lt;a href=&quot;http://en.wikipedia.org/wiki/Hindenburg-class_airship&quot; rel=&quot;nofollow&quot;&gt;Hindenburg-class&lt;/a&gt; airships were huge, but only took 90 passengers plus 10 tonnes of additional cargo and cruised at maximum speed of 70 knots. You can put that much load in 737 that can cruise some 450 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have something large, heavy &lt;em&gt;and&lt;/em&gt; expensive so transport time is important, you can always &lt;a href=&quot;http://www.antonov.com/services/antonov-airlines&quot; rel=&quot;nofollow&quot;&gt;charter&lt;/a&gt; an &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot; rel=&quot;nofollow&quot;&gt;An-124&lt;/a&gt; that can take up to 150 tonnes or even &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-225_Mriya&quot; rel=&quot;nofollow&quot;&gt;An-225&lt;/a&gt; that already carried 189 tonnes (it could probably take more though it would need many refuelling stops then). They can also cruise 450 knots, though they are likely to need some refuelling stops with cargo near maximum load. Things like drilling/mining machinery can easily make up the cost of transport in couple of days. And &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot; rel=&quot;nofollow&quot;&gt;An-124&lt;/a&gt; &lt;em&gt;is&lt;/em&gt; capable of landing on unpaved runways, so it can be used for transport to less developed areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand if you have a lot of something, big container ship takes hundred &lt;em&gt;thousand&lt;/em&gt; tonnes (the already mentioned &lt;a href=&quot;http://en.wikipedia.org/wiki/Emma_M%C3%A6rsk&quot; rel=&quot;nofollow&quot;&gt;Emma Mærsk&lt;/a&gt; has payload capacity 154 000 t) and cruises 20-25 knots. That's not that much slower than the airship and it can take almost four orders of magnitude more cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Hindenburg-class airships were filled with cheap but flammable hydrogen. But after the Hindenburg &lt;a href=&quot;http://en.wikipedia.org/wiki/Hindenburg_disaster&quot; rel=&quot;nofollow&quot;&gt;disaster&lt;/a&gt; that is no longer acceptable and any new airship would have to be filled with expensive helium (in fact Hindenburg was originally designed to use helium, but at the time it was only available in the USA and there was embargo for export to Germany).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And even with helium safety record of airships was never particularly good. They fly low and slow which means they are much affected by the weather and they are sensitive to pressure and temperature changes and heating by the Sun, which makes them difficult to handle even in good conditions.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-11-25T11:01:24.677" LastActivityDate="2014-11-25T11:01:24.677" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9875" PostTypeId="1" AcceptedAnswerId="12700" CreationDate="2014-11-24T08:33:57.573" Score="5" ViewCount="2339" Body="&lt;p&gt;I'm interested in buying a text book about learning to fly so that I'll have some basic knowledge when I begin lessons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone recommended the Airplane Flying Handbook (FAA), but I was wondering if there's an equivalent Australian text and whether it's worth getting?&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="65" LastEditDate="2015-02-27T14:40:00.357" LastActivityDate="2016-08-22T09:45:10.837" Title="Which book should I study to learning flying in Australia?" Tags="&lt;student-pilot&gt;&lt;australia&gt;&lt;books&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9876" PostTypeId="2" ParentId="9872" CreationDate="2014-11-24T09:04:26.880" Score="20" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;what are the technical or mechanical limitations to doing so?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no known material that has a sufficient combination of lightness and strength to support a vacuum that would support the weight of the container on Earth at sea-level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a similar question with a good answer on Physics.se &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://physics.stackexchange.com/q/106295/12613&quot;&gt;Beryllium Vacuum Sphere Boat/Aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible to make a solid rigid evacuated &quot;balloon&quot; out of Beryllium or other elements or alloys?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The currently first answer runs through the maths &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;calculated it over a database of almost 3700 materials including all common aerospace composites, metals and alloys.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and concludes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So in short, the best materials fall short of achieving our aim by a factor of just over 2. It is conceivable we might push up the stiffness / density ratio by perhaps developing some kind of Beryllium foam. For example, a closed cell foam of this Beryllium with a relative density of 0,041 would give a value of about 920 at the expense of lowering the Young's modulus to about 600MPa - however, I have no idea if such a foam is even possible. Alternatively it might be possible to come up with some clever engineering of the envelope geometry to overcome the buckling constraint. However, I suspect the effort is unlikely to pay off with a better boyancy ratio than is already achievable by conventional balloons.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Other related questions &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://physics.stackexchange.com/q/71027/12613&quot;&gt;Is it possible to create a vacuum ballon using concentric partially pressured spheres?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2014-11-24T09:32:29.900" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9877" PostTypeId="2" ParentId="9869" CreationDate="2014-11-24T12:30:20.267" Score="5" Body="&lt;p&gt;Farhan's answer is very good, the only thing I can add is the way your CFI explains you something new. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the moment when you can understand if (s)he knows his/her business good or not. Just ask to clarify something for the second or third time and see, if (s)he tries to explain it in different words, if (s)he can think of another example, if (s)he has a good metaphor from another area for that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If &quot;yes&quot; to all the questions - then yes, (s)he is a good instructor. If no - it can mean two things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;(s)he is a good pilot and understands all this stuff, but (s)he is just not able to teach others&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;rarely, (s)he knows a lot of facts by heart but can not see the whole picture and does not have fundamental understanding&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4016" LastEditorUserId="65" LastEditDate="2014-11-24T14:20:50.540" LastActivityDate="2014-11-24T14:20:50.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9878" PostTypeId="2" ParentId="9873" CreationDate="2014-11-24T12:48:09.540" Score="1" Body="&lt;p&gt;My aircraft (&lt;a href=&quot;http://en.wikipedia.org/wiki/Mooney_M20&quot; rel=&quot;nofollow&quot;&gt;M20M&lt;/a&gt;) fuel selector has left, right, off. My technique (which would apply to any aircraft that doesn't have dual tank feed) is to turn the fuel off when it is parked. I taxi on the lower tank, then switch to the fuller tank to do the runup and take-off on. That assures that both tanks feed fuel, and I'm always departing on the fullest tank.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2014-11-24T16:03:16.327" LastActivityDate="2014-11-24T16:03:16.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9879" PostTypeId="2" ParentId="9869" CreationDate="2014-11-24T13:26:03.133" Score="6" Body="&lt;p&gt;Farhan gave a comprehensive overview. I'd just like to add, picking a suitable instructor can be a personality issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a chat with him, ask yourself:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do you &lt;strong&gt;&lt;em&gt;trust&lt;/em&gt;&lt;/strong&gt; this person?&lt;/li&gt;&#xA;&lt;li&gt;Do you find it comfortable to be with him (or her) in the confined space of the small airplane as you drill your way towards your license?&lt;/li&gt;&#xA;&lt;li&gt;Are you comfortable at the way he (or she) points out your mistakes?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some people like harsh comments, some like a gentle reminder. Perhaps an experienced instructor in the 50s make you feel confident. Perhaps a more passionate instructor in his (her) younger years makes you feel more connected. We end up being closer to some friends and colleagues the same way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's &lt;em&gt;you&lt;/em&gt; who's spending a great deal of time (and money) with the instructor. Besides the objective factors Farhan has listed, don't forget to pick one that you like.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2014-11-24T13:26:03.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9880" PostTypeId="2" ParentId="9873" CreationDate="2014-11-24T13:50:50.223" Score="0" Body="&lt;p&gt;&lt;strong&gt;Is there any merit to this?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possibly. Think of it like parking on a hill and leaving your car in gear/steering into the kerb, in case the handbrake fails.... it's a precaution, rather than a requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a Cessna, the fuel tanks in the wings are very long, wide and flat - so it wouldn't take an excessive amount of bank to allow fuel to slowly move from one tank to the other. If that happened to a great enough degree, in theory the fuel could adversely affect handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chances are that the ramp isn't off-level enough to require it, but assuming that it does block the valve (I'd assume it does, as I'm not sure how else it would work) then there's little harm to be done, and some potential benefit in some circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Does it actually block the crossflow valve?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No idea, I don't own a C172: it seems like a logical conclusion, but I'd check your manual or with the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Just remember to turn it back to dual feed when you set off.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="65" LastEditDate="2014-11-24T14:25:12.420" LastActivityDate="2014-11-24T14:25:12.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9881" PostTypeId="2" ParentId="9873" CreationDate="2014-11-24T13:59:17.457" Score="17" Body="&lt;p&gt;The C172S manual I have says to set the selector to left or right as part of the &quot;securing airplane&quot; checklist:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;8&quot;&gt;&#xA;  &lt;li&gt;Fuel Selector Valve -- LEFT or RIGHT to prevent cross feeding&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I was also taught to set it to right during my initial training. The idea is to prevent cross-contamination or leaks if one tank is compromised. Another reason is that if you park the aircraft on a slope, you could end up with an imbalance between the tanks, as you said. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the POH confirms that it prevents cross feeding, at least in that model: you should always check the POH for your specific aircraft. &lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-24T13:59:17.457" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="9882" PostTypeId="2" ParentId="9872" CreationDate="2014-11-24T14:39:23.693" Score="3" Body="&lt;p&gt;All of the links I've seen are to sites where it is implicitly or explicitly assumed that the dirigible is a homogeneous sphere. This approach does have some merits - any failure has to originate at some point, and if the sphere is absolutely uniform then there is no obvious point of first failure; and in the analogous situation of deep sea exploration spherical construction has been shown to have its uses. However, in practice no material construction is ever completely uniform, and even if one was, until the dirigible was aloft there would be a difference between those points which were in contact with the ground or supporting structures, and those which were not.&lt;/p&gt;&#xA;&lt;p&gt;It seems to me that a much better approach would be to have something which is approximately spherical, but which is supported internally by a complex system of ribs and buttresses, akin to what can be found in a gothic cathedral.&lt;/p&gt;&#xA;&lt;p&gt;For a starting point, take a look at e.g. http://www.cutoutfoldup.com/905-spherical-model---cube.php.&#xA;Imagine this structure scaled up and manufactured to extremely high precision using the strongest available materials, and covered by a thin film so that the interior is completely enclosed. What you'd have is essentially a sphere which is very thick at certain points (i.e where the ribs are) but very thin at others. The ribs would be able to withstand enormous pressures. The other points - not so much. As it stands, it would fail at one of the non-ribbed points. So, not a great advance. But now imagine that the material of the faces is quite strongly curved; that each face is a portion of a sphere which is much smaller and therefore more strongly curved than the overall sphere. These smaller spherical segments should be able to withstand a much larger external pressure than a large sphere of the same thickness.&lt;/p&gt;&#xA;&lt;p&gt;Now imagine each of these bubbles is itself ribbed, with the facets between the ribs occupied by still smaller ribs and bubbles. The construction is effectively fractal, with the repetition at smaller scales occurring as often as is required. The very smallest bubbles would be very highly curved, and therefore very strong. The external pressure exerted on them would be directed to small ribs, which would in turn be directed to larger ribs, and so on. I don't know of any attempts that have been made to construct a vacuum dirigible along those lines, but I don't see why it shouldn't work.&lt;/p&gt;&#xA;&lt;p&gt;EDIT: If we understand that any vacuum achievable on Earth using a mechanical pump is in fact just a partial vacuum, and we therefore use the word &amp;quot;vacuum&amp;quot; as an abbreviation for &amp;quot;partial vacuum&amp;quot;, it follows that &amp;quot;vacuum dirigible&amp;quot; and &amp;quot;lifting gas dirigible&amp;quot; are not mutually exclusive terms. It should be possible to construct a dirigible containing hydrogen or helium at significantly reduced pressure, instead of the slight overpressure that is normal. The rigidity would then have to come from the structural rigidity of the shell instead of from the internal pressure.&lt;/p&gt;&#xA;&lt;p&gt;The big advantage, in the case of a reduced pressure helium dirigible, is that under normal circumstances the loss of helium to the atmosphere should be negligible, unlike a normal balloon where losses are substantial and have to be continuously replenished. The major gas seepages would be from the higher pressure exterior to the lower pressure interior, and any potentially escaping helium would be in effect swimming against that current. It would also be seeping through a rigid material which is likely to be more impervious to the flow than a more flexible material would be. This advantage will become increasingly significant as the price of increasingly rare helium continues to skyrocket.&lt;/p&gt;&#xA;&lt;p&gt;Not that it should be necessary to employ reduced-pressure helium, it's just that doing so would make construction easier by decreasing the pressure difference between interior and exterior to something more easily manageable. But I'm fairly sure that with an intelligently designed shell it would be possible to create a working dirigible even with the interior close to being a hard vacuum. The article cited by RedGrittyBrick in his answer states &amp;quot;the best materials fall short of achieving our aim by a factor of just over 2&amp;quot;, and I am sure that a better structural design would result in MUCH more than double the rigidity of a simple homogeneous sphere for the same mass of material. Supercat's anecdote, below, helps to illustrate that.&lt;/p&gt;&#xA;" OwnerUserId="4368" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-11-27T04:40:35.293" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9883" PostTypeId="2" ParentId="9869" CreationDate="2014-11-24T15:36:13.970" Score="3" Body="&lt;p&gt;To add:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Young vs. Older:  I've noticed the younger CFIs tend to be more familiar with the current FARs and PTS than an older CFI.  This isn't always the case but it makes sense because a younger CFI recently went through the whole process.  However, the older CFIs have more experience and can explain things a few different ways or talk about a time they learned an important lesson in the jet that maybe isn't required under a formal training syllabus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;School vs. Freelancer: I've done both (not what you typically think of as a school however) and I will say I learned different things from each one.  Not contradicting but I feel like I have a wider array of knowledge in aviation.  A school is going to be more expensive but it's also going to be more formal.  A freelancer will be cheaper and he may not have to abide by a strict formal syllabus like the school.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2014-11-24T15:36:13.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9884" PostTypeId="2" ParentId="9822" CreationDate="2014-11-24T16:07:14.947" Score="1" Body="&lt;p&gt;Montgolfier brothers were the first to invent a flying machine...&#xA;But if you are looking for piloted, controlled, heavier-than-air, sustained, flight the Wrights were the first one to do that (their longest flight on December 17, 1903, was 852 feet). Ader didn't really have control or sustained flight. Objections that the Wrights tried to keep their invention under wraps are noted--and sustained. Early on, Santos-Dumont did much more for the science and art of flying in the mind of the public, but he was not the first. Whitehead spun some great yarns but never flew a powered airplane (as vociferous as Whitehead's boosters are, the proof for any powered flights is thin and poorly substantiated). &lt;/p&gt;&#xA;" OwnerUserId="4369" LastActivityDate="2014-11-24T16:07:14.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9885" PostTypeId="2" ParentId="9872" CreationDate="2014-11-24T17:35:14.587" Score="12" Body="&lt;p&gt;The other answers correctly point out the extreme (impossible) materials strength and stiffness requirements of a vacuum balloon.  Another notable point is that the advantage in lifting capacity is small; at standard temperature and pressure the buoyancies of helium, hydrogen and vacuum are respectively 1.096, 1.185 and 1.275 kg/m^3.  So even if you could hypothetically build a vacuum balloon with the same envelope mass as a hydrogen or helium balloon, it wouldn't be able to lift much more payload.&lt;/p&gt;&#xA;" OwnerUserId="3417" LastActivityDate="2014-11-24T17:35:14.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9886" PostTypeId="1" CreationDate="2014-11-24T19:17:38.143" Score="1" ViewCount="530" Body="&lt;p&gt;I have always wondered why most manufacturers put the wings on the bottom of commercial jets. Help would be appreciated.&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2014-11-24T19:17:38.143" Title="Why are the wings of most passenger jets on the bottom?" Tags="&lt;aerodynamics&gt;&lt;commercial-aviation&gt;&lt;airliner&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2014-11-25T03:29:44.463" ContentLicense="CC BY-SA 3.0" />
  <row Id="9887" PostTypeId="2" ParentId="3300" CreationDate="2014-11-24T19:59:28.477" Score="4" Body="&lt;p&gt;e-Volo claims it will use range extender in VC200: &lt;a href=&quot;http://www.e-volo.com/information/how-long-can-you-fly&quot; rel=&quot;nofollow&quot;&gt;http://www.e-volo.com/information/how-long-can-you-fly&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was really curious about that technology, and did small research. My conclusion is, if they consider using Bladon Jets micro turbine to generate electricity it could be a total win!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it seems, the most advanced turbine they have now is 50 kW, 40-kg jet turbine for concept car: &lt;a href=&quot;http://www.bladonjets.com/news/bladon-jets-at-the-geneva-motor-show/&quot; rel=&quot;nofollow&quot;&gt;http://www.bladonjets.com/news/bladon-jets-at-the-geneva-motor-show/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to wikipedia, Volocopter motros consume ~36 kW (18x2 Kw, see E-volo_VC2)&#xA;which means, they can be powered directly by electricity produced by turbine without a need for batteries! Of course there must be small battery pack which provides energy buffer for safe operation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a datasheet on bladonjets website about the fuel consumption of stationary 12 kW turbine, it's 5 liters/hour. Let's say, their 50 kW turbine will consume 5 times more. Which means, 50 kg of fuel will be enough to fly vc200 for at least 2 hours (not 20 minutes, as they say for pure electric e-Volo).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, total weight of system is not that much exceeded by turbine: 40kg turbine + 50 kg fuel + 50 kg chassy. Well, e-volo can alredy carry 2 people=150 kg, right? So existing prototype can lift the generator as is. 50% stronger motors (18*3 kW=54 kW) is not a problem to lift another 150 kg. Although total weight might exceed 450kg - category of ultralight rotor aircraft, but who says that specially designed turbine can't be integrated in e-volo structure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My point is, the technology is there. Just apply it alltogether, and it will make a revolution.&lt;/p&gt;&#xA;" OwnerUserId="4370" LastActivityDate="2014-11-24T19:59:28.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9888" PostTypeId="2" ParentId="9875" CreationDate="2014-11-24T21:51:49.880" Score="2" Body="&lt;p&gt;CASA (the Civil Aviation Safety Authority) has &lt;a href=&quot;http://casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_91314&quot; rel=&quot;nofollow noreferrer&quot;&gt;a number of resources that might be of interest&lt;/a&gt;, in fact a lot of their safety publications and videos are as good as (or better than) the FAA equivalents. As best I can tell they don't have anything equivalent to the textbook-level Airplane Flying Handbook or Instrument Procedures Handbook from the FAA though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find references to the FAA handbooks in some of CASA's &lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD:1001:pc=PC_91054&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAAPs&lt;/a&gt; - for example, the &lt;a href=&quot;http://www.casa.gov.au/wcmswr/_assets/main/download/caaps/ops/5_13_2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Night VFR Rating information&lt;/a&gt; references the Airplane Flying Handbook's section on Night Operations) - so clearly they consider at least some of the information broadly transferrable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9875/flight-text-book-for-australia#comment18978_9875&quot;&gt;Like Farhan mentioned&lt;/a&gt; the operating principles, maneuvers, etc. are going to be largely the same because the plane doesn't care what country it's in. It's the specific regulations (and regulatory citations), airspace design specifics, etc. that will vary but if you're aware of that you can easily pick out the parts that you should pay attention to versus the parts you'll need to go and cross-check in an appropriate Australian reference like &lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_102004&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Part 61 Manual of Standards&lt;/a&gt; for flight training / practical test requirements.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-11-24T21:51:49.880" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9889" PostTypeId="2" ParentId="701" CreationDate="2014-11-24T22:10:38.887" Score="3" Body="&lt;p&gt;Another factor with low-wings is that on take off and landing, the low wing will block airflow over the empennage, reducing rudder and elevator effectiveness. That's why so many low-wings have T-tails, to keep the tail in the flow of air during landing and takeoff.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-11-24T22:10:38.887" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9890" PostTypeId="1" AcceptedAnswerId="9905" CreationDate="2014-11-25T00:41:58.980" Score="10" ViewCount="3109" Body="&lt;p&gt;I would think that having a huge mass spinning around should produce massive gyroscopic forces when turning or pitching.&lt;br&gt;&#xA;There must be some clever way of minimising or eliminating the effects... How is it done?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(An example of the sort of thing I am talking about)&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/QzC9j.jpg&quot; alt=&quot;AWACS&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="319" LastActivityDate="2014-11-26T07:21:23.503" Title="Does huge rotating AWACS radar affect flight characteristics?" Tags="&lt;radar&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9891" PostTypeId="1" CreationDate="2014-11-25T01:53:05.767" Score="8" ViewCount="821" Body="&lt;p&gt;A friend and I are going rim to rim to rim in the Grand Canyon this Wednesday.  It's a 46mi, 20+hr &quot;hike&quot; with some very physically challenging sections.  We are packing the minimal amount needed - meaning not too much extra in case of an emergency - it's especially risky given the below zero (fahrenheit) temperatures this time of year.  Normally for something like this, I would bring my Spot - to call for help if I needed to, but it's not working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I brought my &lt;a href=&quot;http://www.yaesu.com/indexVS.cfm?cmd=DisplayProducts&amp;amp;ProdCatID=204&amp;amp;encProdID=DA07CE6217CCD6F284F47B698B8EB483&amp;amp;DivisionID&quot;&gt;VXA-220&lt;/a&gt;, would it be legal to use it to call for help?  From what I understand, most airliners are tuned into 121.5.  Could I tell them to send a helicopter for rescue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, in a life or death situation it's not going to matter if I'm braking the law.  But it would be nice to know how such a situation would be handled. &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="572" LastEditDate="2015-02-25T11:27:20.853" LastActivityDate="2021-03-31T15:04:49.900" Title="Can you flag down / contact an airplane with a handheld radio in case of emergency?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9892" PostTypeId="2" ParentId="9891" CreationDate="2014-11-25T02:17:20.240" Score="7" Body="&lt;p&gt;Yes, this is legal. As far as I understand, it used to be common practice, and some hiker's beacons still squawk 121.5. Nowadays, more advanced beacons are suggested, but it sounds like yours isn't working. Some police and EMT stations still monitor 121.5, too.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="22864" LastEditDate="2020-02-10T13:38:36.657" LastActivityDate="2020-02-10T13:38:36.657" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="9893" PostTypeId="1" CreationDate="2014-11-25T02:29:24.787" Score="12" ViewCount="1439" Body="&lt;p&gt;I was listening to &lt;a href=&quot;http://www.hellointernet.fm/podcast/25&quot; rel=&quot;noreferrer&quot;&gt;episode #25&lt;/a&gt; of the Hello Internet podcast where Brady Haran mentioned that it's not unheard of for airline employees to rush to their own airplane's respective accident scene to deface the logos and registration numbers painted on the airplane's wings and fuselage. This is apparently done to reduce the damage to the airline's reputation. Below is an picture of the same from an &lt;a href=&quot;http://www.theaustralian.com.au/news/world/thai-airways-tries-logo-cover-up-after-a330-300-skids-off-runway/story-e6frg6so-1226715235550?nk=452313ce6ca44bbb59b1db3d2a47be5b&quot; rel=&quot;noreferrer&quot;&gt;alleged account&lt;/a&gt; of Thai Airways defacing the logo on a crashed (but still very intact) airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O2NCd.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is there any law regarding whether this can be done? Could defacing the logo end up hampering the air crash investigation?&lt;/p&gt;&#xA;" OwnerUserId="504" LastEditorUserId="97" LastEditDate="2014-11-26T03:09:51.810" LastActivityDate="2014-11-26T03:09:51.810" Title="Is defacing the airline logo of a wrecked airplane illegal?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;accident-investigation&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9895" PostTypeId="2" ParentId="9893" CreationDate="2014-11-25T03:22:43.227" Score="14" Body="&lt;p&gt;In the US (you tagged your question FAA) it would most likely be illegal. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=bdbd83b90630a32f49bc9b59cc3b8605;rgn=div5;view=text;node=49:7.1.4.1.12;idno=49;cc=ecfr#se49.7.830_110&quot;&gt;49 CFR 830.10&lt;/a&gt; says (note that the NTSB investigates US accidents, not the FAA):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Prior to the time the Board or its authorized representative takes custody of aircraft wreckage, mail, or cargo, such wreckage, mail, or cargo may not be disturbed or moved except to the extent necessary:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) To remove persons injured or trapped;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) To protect the wreckage from further damage; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) To protect the public from injury.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems highly unlikely that painting over logos would be justified for any of those reasons. On the other hand, this wording leaves the question open of what might happen &lt;em&gt;after&lt;/em&gt; the NTSB takes custody, and in theory an airline could do it with permission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I find it hard to see how this would help the airline because the story would be all over the news anyway, but laws and attitudes vary widely in different parts of the world.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-11-25T03:22:43.227" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="9896" PostTypeId="2" ParentId="9890" CreationDate="2014-11-25T03:33:59.763" Score="5" Body="&lt;p&gt;On the E2 Hawkeye the dish does not rotate very fast (ie, very slowly), and so the torque is probably negligible.  Usually the radomes are designed to help generate lift, and while certainly not as effective as a wing, do offset their own weight quite a bit.  &lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-11-25T03:40:22.743" LastActivityDate="2014-11-25T03:40:22.743" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9897" PostTypeId="2" ParentId="8105" CreationDate="2014-11-25T06:04:47.630" Score="4" Body="&lt;p&gt;TFRs around &quot;volatile situations&quot; on the ground aren't a daily occurrence, but they do happen fairly frequently.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concerns are usually twofold: Events on the ground posing a hazard to aircraft (people shining lasers at aircraft, firing guns at them, etc.), and aircraft posing hazards to each other (News 2, News 4, News 11, and Police helicopters all wanting to cover the same area at the same time and smacking into each other).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are procedures in effect for agencies to request TFRs, and for the FAA to review them. These are covered in detail in &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/fac/1902.html&quot; rel=&quot;nofollow&quot;&gt;FAA JO 7210.3Y, Chapter 19&lt;/a&gt;. Particularly relevant to this situation is 19-2-5 (e): &quot;TFRs issued for law enforcement activities require approval from the ATO Director of System Operations Security (or designee).&quot; - a relatively high level of approval intended to safeguard against the use of TFRs to, for example, keep the media away.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the case of Ferguson the regulatory basis for the TFR is cited as FAR 91.137(a)(1) (&lt;code&gt;to protect persons and property on the surface or in the air from a hazard associated with an incident on the surface&lt;/code&gt;), so presumably their major concern is laser illumination or weapons fire from the ground, and the potential for such incidents to cause a surprised pilot to crash into a building or crowd of people.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-11-25T06:04:47.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9899" PostTypeId="1" AcceptedAnswerId="9901" CreationDate="2014-11-25T14:24:49.410" Score="17" ViewCount="3119" Body="&lt;p&gt;I know there are winds and other effects at very high altitudes but how high can storms with lightning and rain be?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line, let's say you are flying a craft with the ceiling of a U-2, can't you fly over any storm?&lt;/p&gt;&#xA;" OwnerUserId="3699" LastEditorUserId="97" LastEditDate="2014-11-26T21:42:36.177" LastActivityDate="2014-11-26T21:42:36.177" Title="Is there a ceiling on weather patterns?" Tags="&lt;weather&gt;&lt;altitude&gt;&lt;high-altitude&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9900" PostTypeId="2" ParentId="9899" CreationDate="2014-11-25T15:36:47.687" Score="14" Body="&lt;p&gt;No.  Sprites, also known as upper atmosphere lightning, occur from 31 to 56 miles AGL. (source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Sprite_(lightning)&quot;&gt;Wikipedia&lt;/a&gt;) So weather phenomena routinely exceed your U2's altitude by a lot!  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now are Sprites dangerous to flight?  Unknown. I know of no case where an aircraft has been hit by a Sprite.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="524" LastEditDate="2014-11-25T16:05:21.813" LastActivityDate="2014-11-25T16:05:21.813" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9901" PostTypeId="2" ParentId="9899" CreationDate="2014-11-25T15:51:27.740" Score="22" Body="&lt;p&gt;Severe convection will have anvil tops at the tropopause and overshooting tops can penetrate much higher (severe thunderstorm warnings often use a value of 60,000 ft for threats to aircraft).  How high the overshooting tops can get is a balance of the positive buoyancy during parcel ascent against the negative buoyancy once it gets into the warming stratospheric air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A U2 could overfly these storms, but most aircraft are not designed for stratospheric flight (due to the temperature increasing with height in the stratosphere) and any commercial aircraft will be unable to go over these storms.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2014-11-26T18:58:10.073" LastActivityDate="2014-11-26T18:58:10.073" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9902" PostTypeId="2" ParentId="9844" CreationDate="2014-11-25T19:37:59.037" Score="3" Body="&lt;p&gt;I have already found answer for my problem. ACES and FACET from NASA Aviation System Division solve my problem. It should handle all statistical data, it has statistical output as well and it could also handle meteorological data. Currently this SW use FAA and some airline companies to modelate ATM concepts (aviationsystemsdivision.arc.nasa.gov).&#xA;Thanks for all your help!&lt;/p&gt;&#xA;" OwnerUserId="4110" LastActivityDate="2014-11-25T19:37:59.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9903" PostTypeId="2" ParentId="3622" CreationDate="2014-11-25T19:50:45.093" Score="1" Body="&lt;p&gt;If an airline has an accident, the chances are you (as the next set of passengers to board that plane) will be the least of their concerns - if there's an incident then it tends to be a case of all hands to action stations to deal with the media, emergency services, families of any potential victims, provide assistance where possible etc. That said, they do have some procedures they attempt to follow. These vary a little from airline to airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most will make an attempt to contact you via text/email if they have it or via the GDS to your travel agent, depending on how far away you are from your departure day/time. It also depends whether you gave contact information to the carrier or your travel agent, whether your travel agent passed it on or, indeed, whether you used a travel agent at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next set of passengers rightly tends to be second priority after dealing with the incident, however. Often if you're on the next flight, therefore, the communication will be a little slow and the first you'll know about it will be when you arrive at the airport - also remember that there's a good chance you're already at the airport, or are on a connecting flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get to the airport, you'll likely be informed by the staff there who will attempt to get you onto another flight with the same company or another carrier.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As an addition from the comment below, if you're a family member etc who's signed up to flight alerts from the airline in order to hear about delays/diversions etc (some airlines provide this as a service to avoid inconvenience and avoid too much waiting traffic at the terminal), then you'll likely be one of the first priorities. The system is normally set up to send automated or manually-triggered pre-written messages, but in an emergency will usually be used to send a manual message to relevant family members etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously this only applies if you've signed up to the service, and only usually applies to the airline's own service: if you've signed up with a third party flight tracking service, they likely have no more information than you do.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2014-11-26T12:04:49.143" LastActivityDate="2014-11-26T12:04:49.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9904" PostTypeId="2" ParentId="9681" CreationDate="2014-11-25T22:23:32.307" Score="13" Body="&lt;p&gt;Nice question. There are several ways how to get these information.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.fallingrain.com/&quot;&gt;http://www.fallingrain.com/&lt;/a&gt;: free to use, no registration needed. World database of the airports and waypoints. From these information you could easily make DB for waypoints.&lt;/li&gt;&#xA;&lt;li&gt;EUROCONTROL EAD (&lt;a href=&quot;https://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&quot;&gt;https://www.ead.eurocontrol.int/eadcms/eadsite/index.php.html&lt;/a&gt;): free to use, registration needed. Big advantage - real and up to date information for all ECTL countries. But a bit difficult navigation.&lt;/li&gt;&#xA;&lt;li&gt;JeppView (&lt;a href=&quot;http://ww1.jeppesen.com/&quot;&gt;http://ww1.jeppesen.com/&lt;/a&gt;): very expensive SW, but the best in this time. You will find there all information which pilot needs. But it is not real database.&lt;/li&gt;&#xA;&lt;li&gt;Garmin for pilots (&lt;a href=&quot;http://www.garmin.com/en-US/explore/intheair/&quot;&gt;http://www.garmin.com/en-US/explore/intheair/&lt;/a&gt;): another not free SW, very similair to JeppView but lightweighted.&lt;/li&gt;&#xA;&lt;li&gt;NAVIGRAPH (&lt;a href=&quot;http://www.navigraph.com&quot;&gt;http://www.navigraph.com&lt;/a&gt;): Great DB of all things which you need in FMC. But I guess that they have it just for flight simulator.&lt;/li&gt;&#xA;&lt;li&gt;OpenFlights (&lt;a href=&quot;http://openflights.org/data.html&quot;&gt;http://openflights.org/data.html&lt;/a&gt;): free DB of airports, airlines and routes. You could downlod all data in one file :-) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4110" LastEditorUserId="4110" LastEditDate="2014-11-29T15:46:26.090" LastActivityDate="2014-11-29T15:46:26.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9905" PostTypeId="2" ParentId="9890" CreationDate="2014-11-26T07:16:08.233" Score="5" Body="&lt;p&gt;The AWACS surveillance radar components consist of multiple units grouped in 3 locations. Only the antenna array and its electronics are in the &lt;strong&gt;rotodome&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The receivers, radar processors, and  radar control &amp;amp; maintenance panel are in the main cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While fiberglass and rubber make up the outside coating of the dome the inside is mostly hollow except for the antenna rays. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;AWACS aircraft produce greater drag relative to that of  civilian jet liners. Therefore,  engines for AWACS require non recurring engineering(NRE) to handle the dual generator requirements of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to reduce its air drag during take-offs, and while flying endurance speed the dome is tilted down 6° at the front. The rotodome itself is hydraulically rotated. Remember, the Boeing 707/320 from which the Boeing E-3 Sentry was derived  can very easily carry a huge cargo load . Therefore, the addition of a 1.5- 2 ton rotodome makes no difference to an AWAC which in any case is not carrying more than 20 – 30 crew members. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Generally the radome scans at 6 revolutions a minute. When the radar is not operating the radome rotation rate is set at 1 revolution every four minutes&lt;/strong&gt; ( In case of the E-3 it is 1 rotation every 10 seconds). Ergo, the torque that the rotodome produce is very low.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2014-11-26T07:21:23.503" LastActivityDate="2014-11-26T07:21:23.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9910" PostTypeId="2" ParentId="9860" CreationDate="2014-11-26T13:21:40.093" Score="2" Body="&lt;p&gt;I'd say Airships are not popular because they are highly dangerous in rough weather, many losses and casualties resulted from an Airship caught by an Storm. Many variations about Airship shape exist, including recent versions airfoiled as a lifting fuselage, and making use of aerodinamically generated lift for staying airborne. The Airship  concept has periodical remakes, but as of today, with little success. &lt;img src=&quot;https://i.stack.imgur.com/g4bkR.jpg&quot; alt=&quot;Attached images from a 1904 Airship project by an spanish artillery officer, Manuel Rivera-Sempere&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yeBRS.jpg&quot; alt=&quot;M Rivera Airship rear view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2QlQC.jpg&quot; alt=&quot;M Rivera airship flight operation&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2014-11-26T13:27:34.437" LastActivityDate="2014-11-26T13:27:34.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9912" PostTypeId="1" CreationDate="2014-11-26T18:50:56.287" Score="5" ViewCount="1815" Body="&lt;p&gt;I am slightly confused with this notion of the &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow&quot;&gt;Reynolds Number&lt;/a&gt;&lt;/strong&gt;. Specifically, I am looking at airfoil performance at &lt;strong&gt;very low Reynolds number&lt;/strong&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am reading a lot of papers saying things like because it is a small model aircraft, the Reynolds number will be small (so then it is to do with the shape of the obstruction in the fluid flow?). But then I see something like large turbine performance at low speeds involve low Reynolds numbers (from here I would think it is to do with the &lt;em&gt;'quality'&lt;/em&gt; of the fluid flow itself, whether it is laminar or turbulent, uniform etc). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it has something to do with the fluid flow, then why do I see &lt;strong&gt;Reynolds numbers attributed to specific airfoils&lt;/strong&gt; etc? Say that an airfoil has $Re=100000$, what does this mean then? If the fluid is flowing at a very low speed with high viscosity, then how can we make use of this number at all? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do correct me if I'm wrong, I am only beginning to learn these things! &lt;/p&gt;&#xA;" OwnerUserId="4387" LastEditorUserId="65" LastEditDate="2014-11-26T19:40:46.993" LastActivityDate="2018-04-17T17:34:22.053" Title="Is the Reynold's number a function of the fluid flow stream or the obstruction?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;airfoil&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9913" PostTypeId="5" CreationDate="2014-11-26T20:18:10.183" Score="0" Body="" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-11-26T20:18:10.183" LastActivityDate="2014-11-26T20:18:10.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9914" PostTypeId="4" CreationDate="2014-11-26T20:18:10.183" Score="0" Body="Skywriting is the process of using a small aircraft, able to expel special smoke during flight, to fly in certain patterns to create writing readable by someone on the ground." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-11-26T20:18:10.183" LastActivityDate="2014-11-26T20:18:10.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9915" PostTypeId="2" ParentId="9912" CreationDate="2014-11-26T21:05:55.893" Score="4" Body="&lt;p&gt;Maybe it helps to see the Reynolds number as the ratio of inertial to viscous forces. High flow speeds mean high inertial forces, and so lead to high Reynolds numbers. Viscous effects are strongest when the airflow hits the obstacle, and become less strong the longer the air flows around a body, so a short flow path has a low Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end it does not matter if the length of the flow or its speed drive the Reynolds number up. It is the combination of both. I am neglecting the gas properties here, because I assume we talk about air at moderate temperature and do not want to make the issue more complex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airfoils have no Reynolds number per se, flow conditions have. The Reynolds number of a measurement can be doubled by making the chord of the airfoil twice as long at the same airspeed, or by doubling the airspeed at the same chord. The wing of an airplane operates in a range of Reynolds numbers, depending on flight speed. That is why polar diagrams normally contain the results of several test runs rsp. computations, each at a different Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes you see airfoils which are optimized for a particular Reynolds number. To avoid early separation, the recompression area of an airfoil must become proportionally longer the smaller the Reynolds number is at which the airfoil is supposed to function well. At higher Reynolds numbers such an airfoil will still work, but will produce more drag than one which is optimized for a higher Reynolds number. The Reynolds number allows the aircraft designer to pick an airfoil that works well at the combination of speed and chord length for which that airplane is designed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-11-26T21:13:48.913" LastActivityDate="2014-11-26T21:13:48.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9916" PostTypeId="2" ParentId="9872" CreationDate="2014-11-27T09:30:32.630" Score="4" Body="&lt;p&gt;Beneath the argument that it's impossible to build a structure which can withstand the outer pressure, pericynthion pointed to another argument: &#xA;The buoyancies of gas and vaccuum is similar and the higher mass of a vacuum-airship will cancel the benefit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there is even more: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airships usually include a balloon filled with air. If the ship ascends, the gas expands and the air is pressed out. (see &lt;a href=&quot;http://www.americanblimp.com/fly.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.americanblimp.com/fly.htm&lt;/a&gt;)&#xA;This way, the inner and outer pressure is equal and there is no additional stress on the hull due to overpressure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the buoyancy does not decrease: In an altitude of about 5.8km, air pressure is reduced to 50%, and so is the buoyancy for a &lt;em&gt;fixed volume&lt;/em&gt;. If you let the gas expand, it will expand to twice its volume. Twice the volume times 50% buoyancy gives you 100% buoyancy again. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;But&lt;/strong&gt; a fixed volume of vacuum will not expand and have only 50% of its buoyancy at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, 5.8km altitude is very much for an airship, but the numbers are nice to show the effect. And due to the exponential nature of the air pressure, &lt;strong&gt;a gas-filled airship which allows the gas to expand has a higher buoyancy than a vacuum airship with fixed volume above 600m for hydrogen filled and 1200m for helium filled ships&lt;/strong&gt;. Here is a plot comparing the buoyancy of 1m³ of vacuum to 1m³ gas at sealevel:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/kk6i4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By the way: This is the reason why weather balloons have a flexible hull or seem to be partially filled only at sea level)&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2014-11-27T09:30:32.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9917" PostTypeId="1" AcceptedAnswerId="9918" CreationDate="2014-11-27T10:43:47.713" Score="16" ViewCount="7067" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/274558/&quot; rel=&quot;noreferrer&quot;&gt;this discussion&lt;/a&gt;(&lt;a href=&quot;http://www.flightsimworld.com/forums/topic/184188-aircraft-fuselage-flex/&quot; rel=&quot;noreferrer&quot;&gt;2nd&lt;/a&gt;)(&lt;a href=&quot;http://www.turbulenceforecast.com/forums/archive/index.php/t-1762.html&quot; rel=&quot;noreferrer&quot;&gt;3rd&lt;/a&gt;) and &lt;a href=&quot;https://www.youtube.com/watch?v=fu0JiW09x1E&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt; there is more fuselage bending in turbulence on the Boeing 757 than on other Jets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does the B757 fuselage bend more on turbulence? &#xA;What are the factors related into fuselage bending? &#xA;I always thought there is only fuselage bending during take-off and landing on tarmac. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ncIqg.jpg&quot; alt=&quot;757cab&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/efzS8.jpg&quot; alt=&quot;757bend&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Picture Zoomed, fuselage shows flexing. &lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="1360" LastEditDate="2014-12-03T23:19:41.413" LastActivityDate="2018-11-02T12:11:36.577" Title="Why does the 757 fuselage bend more on turbulence than those of other airplanes?" Tags="&lt;aircraft-design&gt;&lt;boeing-757&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9918" PostTypeId="2" ParentId="9917" CreationDate="2014-11-27T12:21:13.627" Score="27" Body="&lt;p&gt;This is really two questions&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;em&gt;Why does a fuselage bend?&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Why does the 757 fuselage bend more than others&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I'll give the simple answers here. You can go into a LOT of detail, but the detailed answers are mainly just bringing more information on design/engineering differences into the simple answers (eg composites bend/break in a different way to aluminium)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why does a fuselage bend?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, it's because the lifting force doesn't support the entire fuselage equally. Drag and the aerodynamic forces created by the fuselage itself will also affect things, but it's mainly due to the fact that &lt;em&gt;the lifting force is centred on two points of the fuselage, while the weight is spread along it&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift is generated, primarily, in two places: the wings and the horizontal stabiliser (some is generated in the body too, but relatively little). Most of that lift is generated at the wings, which are attached in the middle(-ish) of the fuselage. Imagine balancing a ruler (fuselage) on your finger (wings), then stacking coins along the top of the ruler. The heavier the rule, and the more &quot;lift&quot; your finger has to provide, the more the ruler flexes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, lift isn't constant - turbulence means that over a few second the lift provided by the wings can change quite a lot. Imagine you start bouncing your finger up and down, creating &quot;turbulence&quot;: the ruler will flex and unflex as it absorbs that changing force. This is the fuselage flex seen in aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage will also bend while landing or taking off, because you're again changing how the weight of the fuselage is supported: the weight is transferred from the wing root/spar to the landing gear. And the final obvious one is that the weight of the aircraft changes during the flight due to fuel burn etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why does the 757 flex more than other airliners?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, for one thing I don't see any sources for this other than &quot;I've heard that&quot; (the links you provided are mostly hear-say too), but I have seen it stated as fact. Let's, for the moment, assume it's fact... the theory applies regardless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 757 will flex more than &lt;em&gt;some&lt;/em&gt; other airliners (although likely less than &lt;em&gt;some&lt;/em&gt; others) because of its design, construction and the build materials. The simplest explanation is that it's one of the longest narrow-body airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does that mean? Well, it means it's one of the longest, thinnest fuselages around. This gives us two causes:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The 757 flexes more than other large airliners because anything bigger than it is a wide-body aircraft, which will resist bending more than a small, narrow bodied thin one&lt;/li&gt;&#xA;&lt;li&gt;It flexes more than other small airliners because any other narrow body is lighter and shorter than the 757, providing less force on the fuselage and requiring a smaller lifting force.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;TL;DR: Flex is caused by lift acting mostly in the middle(ish) of the fuselage, while the weight of the fuselage and other forces on it are spread out along the length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Overall, then, the 757 is on the boundary between lighter, narrow bodied aircraft and larger, wide bodied ones. Anything smaller than it weighs less so stresses the narrow body less. Anything larger has a bigger, stronger fuselage.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2018-11-02T12:11:36.577" LastActivityDate="2018-11-02T12:11:36.577" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="9919" PostTypeId="1" AcceptedAnswerId="9920" CreationDate="2014-11-27T15:10:03.647" Score="31" ViewCount="18334" Body="&lt;p&gt;Why is &lt;a href=&quot;http://en.wikipedia.org/wiki/Paro_Airport&quot;&gt;Paro Airport&lt;/a&gt; (currently the only international airport of &lt;a href=&quot;http://en.wikipedia.org/wiki/Bhutan&quot;&gt;Bhutan&lt;/a&gt;) considered one of the most dangerous airports to land in the world?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it because of the mountains? In my opinion, &lt;a href=&quot;http://en.wikipedia.org/wiki/Princess_Juliana_International_Airport&quot;&gt;Princess Juliana International Airport&lt;/a&gt; is also as challenging as Paro.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why do the pilots need a special certification to land there? &lt;/li&gt;&#xA;&lt;li&gt;How do they achieve this certificate?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="62" LastEditDate="2014-12-01T14:40:05.730" LastActivityDate="2017-04-11T14:10:31.360" Title="Why is a special certification needed to land at Paro Airport?" Tags="&lt;landing&gt;&lt;flight-training&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9920" PostTypeId="2" ParentId="9919" CreationDate="2014-11-27T16:29:07.987" Score="53" Body="&lt;p&gt;The approach to Paro is unbelievably complicated. It is flown visually through a valley with high mountains all around and &lt;em&gt;no sight of the airport until the last moment.&lt;/em&gt; Here is a cut of a map with the approach paths:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ME7hh.png&quot; alt=&quot;Area around Paro Airport (from Google Map) with approach directions&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approach to runway 15, marked in red, is worse in this regard. The ridge is rather close to the airport, so the final turn usually ends over the runway threshold. The wings get level with 30–50 ft (10–15 m) remaining only (&lt;a href=&quot;https://www.youtube.com/watch?v=rmGy7qcDwQU&quot; rel=&quot;noreferrer&quot;&gt;here's a video&lt;/a&gt;). The approach to runway 33, marked in blue, allows a bit more of a straight final, but not by much. In either case the aircraft must emerge from the turn with correct altitude, speed and rate of descent. So the pilot has to know landmarks in the valley and how to judge correct approach profile by them. The approaches also often involve turning around higher in the valleys which again must be done by landmarks at places where it is known to be possible. It is this knowledge pilots have to demonstrate before they can attempt the approach (as pilots in command).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other airports where pilots have to receive special training to be permitted to fly there, for example the &lt;a href=&quot;http://en.wikipedia.org/wiki/Samedan_Airport&quot; rel=&quot;noreferrer&quot;&gt;Samedan Airport&lt;/a&gt; near St. Moritz in Switzerland, which is similar mix of high altitude, high mountains around and visual approach, though it's still a lot easier as the airport is visible from much greater distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is however nothing similarly difficult on Princess Juliana Airport. It appears approaches to Princess Juliana are only flown to runway 10 and these are over flat sea and flat beach. The runway is visible from great distance and the approach is straight. The featureless water makes it slightly harder to judge height than solid ground, but that's what the approach lights (VASI/PAPI) and distance-altitude table are for (there is no ILS at TNCM, only VOR-DME). And there are many airports with approach over water, so it's nothing unusual for the pilots. If there was approach to runway 28, it would have to be off-axis to avoid the hills on the island, but it does not appear to be used at all.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The pilot, Marek Tůma, who ferried in and for first 3 months commanded the ATR-42-500 A5-RGH, wrote a 4-part &lt;a href=&quot;http://www.planes.cz/cs/clanky/483/&quot; rel=&quot;noreferrer&quot;&gt;report&lt;/a&gt; (&lt;a href=&quot;http://www.planes.cz/cs/clanky/484/&quot; rel=&quot;noreferrer&quot;&gt;2&lt;/a&gt;, &lt;a href=&quot;http://www.planes.cz/cs/clanky/485/&quot; rel=&quot;noreferrer&quot;&gt;3&lt;/a&gt;, &lt;a href=&quot;http://www.planes.cz/cs/clanky/492/&quot; rel=&quot;noreferrer&quot;&gt;4&lt;/a&gt;; unfortunately in Czech) about flying in Bhutan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to that the training involved:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Couple of hours on simulator (in Bangkok).&lt;/li&gt;&#xA;&lt;li&gt;Then they were permitted to ferry the plane to Paro.&lt;/li&gt;&#xA;&lt;li&gt;Flight as observers with the training captain who showed them all the relevant landmarks in reality.&lt;/li&gt;&#xA;&lt;li&gt;Some practice circuits.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;They couldn't fly with the training captain in the other seat, because they were ATR-42 pilots and the training captain flies A320-family (and possibly still has rating for the older BAe146, but not ATR-42).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He also wrote that while on early flights when temperatures are still low the performance is good, later in the day it becomes marginal and they often needed to follow the valley quite far before they managed to climb above the mountains. Careful planning and weight and balance calculation was always necessary.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="13297" LastEditDate="2017-04-11T14:10:31.360" LastActivityDate="2017-04-11T14:10:31.360" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9921" PostTypeId="2" ParentId="9919" CreationDate="2014-11-27T16:34:53.010" Score="30" Body="&lt;p&gt;This is really two questions&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;em&gt;Why does Paro need special certification?&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Why doesn't Princess Juliana need special certification?&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I'll answer both, which I think answers your overall question about &quot;Why does Paro need special certification &lt;em&gt;but&lt;/em&gt; Princess Juliana doesn't?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why does Paro need special certification?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You've mostly answered this, it's because it's high up and in challenging terrain.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less dense air at higher altitude requires a higher groundspeed on landing&lt;/li&gt;&#xA;&lt;li&gt;The nature of the valley means there are almost constant, unpredictable gusty crosswinds. Nasty at any airport, but worse here due the terrain&lt;/li&gt;&#xA;&lt;li&gt;The runway is short &lt;em&gt;considering the terrain&lt;/em&gt; - it's not a short runway per se, but it increases the chance of needing to go around, which is tricky&lt;/li&gt;&#xA;&lt;li&gt;It's very hard to go around compared to most airports - you need to know exactly where you're flying, rather than just maintaining runway heading and climbing out until given other instructions&lt;/li&gt;&#xA;&lt;li&gt;You're in mountainous terrain (lots of things to crash into!)&lt;/li&gt;&#xA;&lt;li&gt;The approaches are &lt;strong&gt;visual&lt;/strong&gt; - added to the fact it's a difficult approach in the first place. The lack of ILS makes landing harder, you don't know if you're on the glideslope or not&lt;/li&gt;&#xA;&lt;li&gt;And this has been covered by the other points, but it's worth repeating.... There are 5000m high mountains all around it, dramatically limiting approach and escape options&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's real no question that Paro is a difficult airport to land at: it requires an unusual approach, special awareness, a higher than normal level of skill and is very unforgiving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why doesn't Princess Juliana need special certification?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because although the videos look very dramatic, simply put, it's not very hard to land at. The runway is short compared to most international airports, but it is &lt;strong&gt;long enough&lt;/strong&gt;. Once the runway is beyond the minimum required for an aircraft, it's long enough and that's all there is to it. A longer runway may in theory require fewer go-arounds, but a &quot;long enough&quot; runway doesn't make landing there hard&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the runway length which, as just described, isn't actually a problem, there's nothing too difficult about it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's got nice, open approaches at each end&lt;/li&gt;&#xA;&lt;li&gt;Clear glideslopes&lt;/li&gt;&#xA;&lt;li&gt;It's at sea level, maneuvering is about as easy as it gets&lt;/li&gt;&#xA;&lt;li&gt;It's an Instrument approach, you can make it in almost any weather&lt;/li&gt;&#xA;&lt;li&gt;There's loads of time/space to make a missed approach and go around&lt;/li&gt;&#xA;&lt;li&gt;There are no 5000m mountains around it, just lots of sea - and if you crash into the sea, you would have crashed into the ground anywhere else, so this isn't any more difficult than any other airport&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's not the easiest airport ever to land at, but it's not unusually difficult... although it certainly &lt;strong&gt;looks&lt;/strong&gt; very dramatic, with the videos of Airliners sweeping over the top of a beach and road. The important thing to note is that the beach and road are both well below the glideslope - aircraft only really care about obstructions near or above the regular glideslope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although that beach approach looks crazy it actually poses no problems whatsoever for an aircraft - the jets are still comfortably on the glideslope: they don't care if the last section before the runway is grass, sand, a road etc, they were always going to be at that altitude.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You since edited the question to ask how they get this certification - you'd have to go and work for Druk Air (Royal Bhutan Airlines). Until recently they were the only carrier who flew into or out of the airport, and they work with the Bhutan government to certify pilots.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3504" LastEditDate="2014-12-01T19:23:25.237" LastActivityDate="2014-12-01T19:23:25.237" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9922" PostTypeId="2" ParentId="6348" CreationDate="2014-11-27T19:09:52.143" Score="0" Body="&lt;p&gt;Nobody mentioned the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/&quot; rel=&quot;nofollow&quot;&gt;FAA handbooks&lt;/a&gt; yet, so I will. The FAA has a cornucopia of handbooks on various aviation-related topics, and in particular has a few on aerodynamics. They have the advantage of being easy to find, written to be understandable by anyone, and available free of charge. Here are a few&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, I would recommend reading &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf&quot; rel=&quot;nofollow&quot;&gt;aerodynamics of flight&lt;/a&gt;. It was written for student private pilots, so everything discussed pertains to aviation, and it does not assume that the reader has more that a high school education. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other books, that are aimed at the same public, but that expose the aerodynamics of &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch02.pdf&quot; rel=&quot;nofollow&quot;&gt;helicopters&lt;/a&gt; or of &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/glider_handbook/media/gfh_ch03.pdf&quot; rel=&quot;nofollow&quot;&gt;gliders&lt;/a&gt;, though the contents of these books partially overlap, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/airship_aerodynamics.pdf&quot; rel=&quot;nofollow&quot;&gt;this manual&lt;/a&gt; is a bit outdated, but the first section features a useful glossary of aero terms.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-11-27T19:09:52.143" CommentCount="0" CommunityOwnedDate="2014-11-27T19:09:52.143" ContentLicense="CC BY-SA 3.0" />
  <row Id="9923" PostTypeId="2" ParentId="9917" CreationDate="2014-11-27T20:12:30.660" Score="16" Body="&lt;p&gt;First, there is no fuselage bending to be seen in the linked movie. What might look like flexing is actually the seats and the interior panels moving due to inertial forces. In turbulent weather the aircraft will be shaken by gusts, and this causes the movement between seats and panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, in the picture the flaps are in take-off, shifting the center of lift aft, and the tail pushes the nose up, so it needs to create a considerable downforce. This is transferred via the rear fuselage to trim the moments of wing lift and weight, which attacks at the center of gravity. See the sketch below; blue are aerodynamic forces and red the stresses in the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zBMu2.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your enlarged picture shows buckling of the lower rear fuselage panels. This is normal behavior under stress and enables them to take higher loads. When a plate is stressed, it first deforms in-plane, but when &lt;a href=&quot;http://www.steel-insdag.org/TeachingMaterial/Chapter7.pdf&quot; rel=&quot;noreferrer&quot;&gt;compression loads exceed a critical value, the plate responds by buckling out-of-plane&lt;/a&gt;. The sketch below shows the general relation between stress and strain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ECbOr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the 757 flexing more than other airplanes: Maybe this has to do with the slender forward fuselage. This leads to more flexing at the same strain in the aluminum panels. The rear fuselage is higher to accommodate more baggage. During development Boeing engineers were afraid that directional stability might be insufficient with a higher forward fuselage, so the cross section was restricted to that of a Boeing 737. But there are aircraft with even more slender fuselages like the MD-90 (see below). They should flex at least as much as the 757.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ajYgb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any aircraft part will flex when subjected to stresses, and the fuselage is no exception. Especially the forward part will create lift and side force during flight, its own mass will cause it to bend down the more you move away from the wings, especially when subjected to g-forces, and tail-mounted control surface deflections will add more stress and bending, like in your picture. Fuselage flexing is actually severe enough that in flight test the fuselage will carry inertial sensors at several locations to collect enough data.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-02T11:44:20.560" LastActivityDate="2015-02-02T11:44:20.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9925" PostTypeId="1" AcceptedAnswerId="9927" CreationDate="2014-11-27T22:07:05.807" Score="22" ViewCount="40676" Body="&lt;p&gt;They have rafts and life jackets on board and before takeoff, passengers are explained how to use that equipment, but have any evacuations ever happened successfully?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="595" LastEditDate="2014-11-28T07:00:05.567" LastActivityDate="2018-09-27T20:38:41.753" Title="Has a commercial airliner ever crash-landed in an ocean?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;ditching&gt;" AnswerCount="8" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9926" PostTypeId="2" ParentId="9925" CreationDate="2014-11-27T22:48:23.710" Score="16" Body="&lt;p&gt;Yes - it happened in &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;2009 in the Hudson&lt;/a&gt; (well it's a river), and it happened in 1996 &lt;a href=&quot;http://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961&quot;&gt;Ethiopian Airlines Flight 961&lt;/a&gt; as far as I know.&lt;/p&gt;&#xA;" OwnerUserId="4390" LastEditorUserId="65" LastEditDate="2014-11-27T23:46:13.723" LastActivityDate="2014-11-27T23:46:13.723" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9927" PostTypeId="2" ParentId="9925" CreationDate="2014-11-27T23:44:35.743" Score="27" Body="&lt;p&gt;Yes, commercial airplanes have landed or crash landed in water many times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I am not mistaken, you are asking about scenarios when the on-board &lt;a href=&quot;http://en.wikipedia.org/wiki/Personal_flotation_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;life jackets&lt;/a&gt; and life raft are used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Water_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here&lt;/a&gt; is a list of water landings. Examples when a life raft was used are (in addition to &lt;a href=&quot;https://aviation.stackexchange.com/q/9925/65#comment19122_9925&quot;&gt;ratchet freak's mentions&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 22 October 1962, a Northwest Airlines DC-7C with 7 crew and 95&#xA;  passengers made a successful water landing in Sitka Sound. ... The&#xA;  plane stayed afloat for 24 minutes after coming to rest in the water,&#xA;  giving the occupants ample time to evacuate into life-rafts.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In 1993, &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_605&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines Flight 605&lt;/a&gt;, a Boeing 747–409, ended up in&#xA;  water after it overran runway 13 ... All of the 396 occupants donned&#xA;  life-vests, boarded the eight slide/rafts and no fatalities resulted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-11-27T23:44:35.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9928" PostTypeId="1" AcceptedAnswerId="9935" CreationDate="2014-11-27T23:52:00.187" Score="17" ViewCount="7154" Body="&lt;p&gt;In &#xA;&lt;em&gt;Fire-involved Accidents and Incidents Reviewed&lt;/em&gt;&#xA;, Rudolf Kapustin stated in 1993 that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Nearly all aircraft accident fatalities that are not the result of&#xA;  crash/impact injuries are the result of post-crash fires and the&#xA;  inability to exit aircraft quickly, which in most cases is attributed&#xA;  to incapacitation from toxic smoke, fumes or injuries.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This makes me wonder why airlines don't provide smoke hoods for their passengers in case of a fire, the same way they provide life vests in case of a water landing. If flights crossing a body of water must have life vests available for all passengers in case of a water landing, why not make an equivalent law for smoke hoods in case of a cabin fire?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Protective breathing equipment, or smoke hoods are protective head coverings that prevent wearers from breathing the smoke, particulates and toxic gases generated in a fire. There are two main types of hoods: those that have a source of breathable air and those that just filter the particles out of the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The smoke hood for aircraft passengers wouldn't need to be a firefighting grade smoke hood, just enough to get everyone out of the plane &lt;strong&gt;before&lt;/strong&gt; they get asphyxiated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, the recommendation in case of a cabin fire is to stay near the ground where the air is more breathable. If passengers could be equipped with smoke hoods, they could walk out instead, which would likely make an evacuation faster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted, the smoke hoods would be used on rare occasions, they have a cost, take up space, weigh something, and you have to explain to the passengers what to do with one in case an accident happens. So it is unlikely that an airline would spontaneously decide to equip all seats with an emergency smoke hood. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But life vests have all of those disadvantages as well. It seems to me that these hoods would not be any heavier or any more expensive than the life vests, and might be used on more occasions than the life vests. I've seen smoke hoods the size of a soda can, so finding a place to fit one on each seat can't be so hard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why aren't plane equipped with emergency smoke hoods for passengers?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2017-08-16T08:28:06.167" Title="Why don't airlines provide smoke hoods?" Tags="&lt;safety&gt;&lt;equipment&gt;&lt;fire&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9929" PostTypeId="2" ParentId="7444" CreationDate="2014-11-28T06:38:08.883" Score="21" Body="&lt;p&gt;The tail arrangement was initially chosen to &lt;a href=&quot;http://www.airspacemag.com/flight-today/the-man-who-invented-the-predator-3970502/?all&quot;&gt;protect the propeller from touching the ground first&lt;/a&gt;. The &lt;a href=&quot;http://www.designation-systems.net/dusrm/app4/amber.html&quot;&gt;configuration of what later became the Predator&lt;/a&gt; was initially designed to be launched from a submarine, so it needed to fit into a torpedo tube when folded. When this configuration was scaled up, the general arrangement was kept. Now the tail surfaces are much larger relative to the propeller, so the initial reason for their location is not easily discernible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high aspect ratio $AR$ of the Predator's unswept wing gives it a much higher lift curve slope than that of the swept wing of an airliner, so less rotation is needed to increase lift for take-off. Also, the highly cambered airfoil has a very low, negative zero-lift angle of attack, so at level attitude the wing already produces substantial lift. This was chosen to fly at optimum endurance speed with a horizontal fuselage attitude. The lift coefficient $c_L$ for optimum endurance is $$c_L = \sqrt{3\cdot\pi\cdot AR\cdot\epsilon\cdot c_{D0}}$$&#xA;At that lift coefficient, induced drag $c_{Di} = \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$ is three times bigger than zero-lift drag $c_{D0}$, which means endurance is longest when the aircraft flies at a high lift coefficient and low speed. Basically, the Predator is a point design, flying almost always at the same attitude and lift coefficient. Ground attitude equals flight attitude, and a rotation beyond a few degrees will make it stall.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-02T18:30:37.013" LastActivityDate="2015-06-02T18:30:37.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9930" PostTypeId="2" ParentId="9928" CreationDate="2014-11-28T10:44:25.490" Score="4" Body="&lt;p&gt;Factors that airlines are likely to consider&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;extra cost and weight of equipment&lt;/li&gt;&#xA;&lt;li&gt;additional time and cost to check equipment regularly&#xA;&lt;ul&gt;&#xA;&lt;li&gt;still present after each flight&lt;/li&gt;&#xA;&lt;li&gt;in good working order regularly&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;need to instruct passengers&lt;/li&gt;&#xA;&lt;li&gt;need to supply boarding parents with specialized devices for infants and small children&#xA;&lt;ul&gt;&#xA;&lt;li&gt;and provide extra instruction&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;fatalities may rise due to inevitable incorrect use (&lt;a href=&quot;https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_961#Crash_landing&quot; rel=&quot;nofollow&quot;&gt;example&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;what happens when the panicking passenger by the exit puts their hood on back-to-front?&lt;/li&gt;&#xA;&lt;li&gt;how to introduce intrusive and effective instruction without increasing fear of flying?&lt;/li&gt;&#xA;&lt;li&gt;Every new airplane model must receive a 90-second evacuation drill certification from the FAA before it can fly. Can this be done wearing hoods?&lt;/li&gt;&#xA;&lt;li&gt;In what circumstances are flight crew likely to instruct passengers to don hoods?&lt;/li&gt;&#xA;&lt;li&gt;How likely are passengers to be incapacitated before they can find and complete donning of smoke hoods?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-11-28T10:44:25.490" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9931" PostTypeId="1" CreationDate="2014-11-28T17:40:52.667" Score="15" ViewCount="2610" Body="&lt;p&gt;How can people launch balloons privately (filled with helium or hydrogen) that reach the altitude of 30,000 feet? Isn't that a safety risk in the same way as geese?&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="1467" LastEditDate="2016-05-25T10:38:45.950" LastActivityDate="2021-04-24T19:48:19.280" Title="How does one launch unmanned high-altitude balloons without posing a safety risk to aviation?" Tags="&lt;safety&gt;&lt;balloon&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9932" PostTypeId="2" ParentId="9928" CreationDate="2014-11-29T00:11:06.057" Score="4" Body="&lt;p&gt;Another relevant point is that a fire in a confined space can use up all the oxygen in the air very quickly so, for a hood to be useful, it probably has to include its own oxygen supply. But, now, you've increased the amount of oxygen within the plane's fuselage so the hoods might actually make the fire worse and all the people who would have died from smoke inhalation might just end up dying from burns instead.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-11-29T00:11:06.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9933" PostTypeId="2" ParentId="9925" CreationDate="2014-11-29T01:08:19.817" Score="3" Body="&lt;p&gt;I'm not sure if this fits in with &quot;commercial airline&quot;, but there was also a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;nofollow&quot;&gt;Cessna 208 &quot;Grand Caravan&quot;&lt;/a&gt; that crashed just off the coast of Kalaupapa, Molokai, Hawaii about a year ago on December 11, 2013. It made an emergency landing into the Pacific Ocean after the engine failed just after take off. The aircraft was chartered by &lt;a href=&quot;http://en.wikipedia.org/wiki/Makani_Kai_Air&quot; rel=&quot;nofollow&quot;&gt;Makani Kai Air&lt;/a&gt; to deliver passengers from &lt;a href=&quot;http://en.wikipedia.org/wiki/Kalaupapa,_Hawaii&quot; rel=&quot;nofollow&quot;&gt;Kalaupapa&lt;/a&gt; to &lt;a href=&quot;http://en.wikipedia.org/wiki/Honolulu&quot; rel=&quot;nofollow&quot;&gt;Honolulu&lt;/a&gt;. One person (a state health department director) was killed in the crash. The crash was also &lt;a href=&quot;https://www.youtube.com/watch?v=QguEfBMhpyc&quot; rel=&quot;nofollow&quot;&gt;captured on video&lt;/a&gt; with a GoPro camera by one of the passengers.&lt;/p&gt;&#xA;" OwnerUserId="892" LastActivityDate="2014-11-29T01:08:19.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9934" PostTypeId="2" ParentId="9681" CreationDate="2014-11-29T18:46:41.673" Score="8" Body="&lt;p&gt;I use the National Flight Data Center at &lt;a href=&quot;http://nfdc.faa.gov&quot; rel=&quot;noreferrer&quot;&gt;http://nfdc.faa.gov&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had to write them a letter explaining why I wanted the data (&lt;a href=&quot;http://fplan.sf.net&quot; rel=&quot;noreferrer&quot;&gt;http://fplan.sf.net&lt;/a&gt;) and they provided me with a login.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, every 56 days, they send me an email telling me there's an update available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bad news: they recently switched from a flat file to some unbelievably convoluted xml format that I haven't yet written a parser for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it comes with a disclaimer that the data is not approved for navigation. Given that I've already found two minor errors in it, just in the SF Bay area, that's understandable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I forgot to mention that I keep a subset of the data on-line at SourceForge. I try to keep it up to date. It's at the &lt;a href=&quot;https://sourceforge.net/projects/fplan/files/fplan-db/&quot; rel=&quot;noreferrer&quot;&gt;Fplan project&lt;/a&gt;. These files are in the old &quot;nav&quot; format; documentation is included in the zip file.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone needs these files, they're freely available and I'm happy to make small additions to the data if anybody wants, since I already have the tools to parse the FAA data files. I'm also happy to share the tools if anybody wants.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="87" LastEditDate="2015-08-26T18:22:28.663" LastActivityDate="2015-08-26T18:22:28.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9935" PostTypeId="2" ParentId="9928" CreationDate="2014-11-29T19:39:21.017" Score="21" Body="&lt;p&gt;This is an issue on airline passenger safety that has been debated since a very long time, and there are various arguments for and against the use of smoke hoods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A classic example which showed the requirement for smoke hoods was the British Airtours Flight 28M, which had an engine failure during its take off roll at Manchester International Airport in August 1985. The ensuing fire and black smoke made the evacuation very difficult, and as a result 48 people died from smoke inhalation. Perhaps, the presence of smoke hoods could have saved many more lives. But at the same time, the subsequent investigation revealed there were other factors which contributed to the tragedy, such as the restricted access to exits and standard operating procedures which did not take into account the wind direction before turning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I have read and researched, smoke hoods might involve unnecessary time wasted in wearing them. After all, airline crews are trained to evacuate a passenger aircraft within 90 seconds with half the emergency exits blocked. This time is considered sufficient to escape toxic smoke related fatalities. Secondly, the passengers might require some detail as in how to use them. Surely, space, weight and cost issues are secondary and can easily be overcome, but these are other issues which prevent their use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of a fire upon crash landing, the immediate action is to evacuate and go as far away as possible from the aircraft. Since the passenger will not be staying in the smoke, it does not seem logical to provide smoke hoods. A water landing on the other hand might require passengers to float on the water surface for some time till emergency services arrive. This necessitates the need for a life jacket, otherwise lives can be lost due to drowning.&lt;/p&gt;&#xA;" OwnerUserId="189" LastActivityDate="2014-11-29T19:39:21.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9936" PostTypeId="2" ParentId="9925" CreationDate="2014-11-29T19:41:46.787" Score="7" Body="&lt;p&gt;Yes. A &lt;a href=&quot;http://en.wikipedia.org/wiki/1954_Cathay_Pacific_Douglas_DC-4_shootdown&quot; rel=&quot;noreferrer&quot;&gt;Cathay Pacific DC-4 (technically a C-54) was shot down by Chinese fighters&lt;/a&gt; off the coast of Hainan island on 23 July 1954. With his rudder and right aileron shot off, fuel tanks on fire, and the #4 engine down, the pilot ditched into the ocean. Of the 19 people on board (including 3 flight crew and 3 cabin crew,) 9 died either from bullets or the ditching into the ocean. The remaining 10 floated in the water for a while and then inflated and boarded one of the rafts. The passengers remained on board the raft for several hours until a USAF SA-16 Albatross flying boat was finally able to find a spot were it could land on the rough seas, then taxied to the raft and pulled everyone on board before taking off and flying to Hong Kong. A passenger who had been badly injured died en route to Hong Kong. The remaining 9 people survived.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-11-29T19:41:46.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9937" PostTypeId="2" ParentId="9925" CreationDate="2014-11-29T19:49:08.530" Score="4" Body="&lt;p&gt;Yes there have been several such instances. To name a few, some of which were captured on camera:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ethiopian Airlines Flight 961. You can see the actual crash landing video &lt;a href=&quot;https://www.youtube.com/watch?v=SqKdVo_IcGs&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. 125 of the 175 passengers and crew on board died.&lt;/li&gt;&#xA;&lt;li&gt;US Airways flight 1549. The video was caught on a cctv &lt;a href=&quot;https://www.youtube.com/watch?v=IC7gBV_jUR0&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt;. All passengers and crew were safe.&lt;/li&gt;&#xA;&lt;li&gt;Tuninter Flight 1153. 23 out of 39 survived. No film exists but it was dramatized in a Mayday episode &lt;a href=&quot;https://www.youtube.com/watch?v=aCrZwctnNWo&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There have been many other evacuations, some successful and some not so successful. You can get a detailed list &lt;a href=&quot;http://en.wikipedia.org/wiki/Water_landing#Commercial_aircraft&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="189" LastActivityDate="2014-11-29T19:49:08.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9938" PostTypeId="2" ParentId="6348" CreationDate="2014-11-29T20:04:15.450" Score="0" Body="&lt;p&gt;I don't know a book which will provide you with a thorough mathematical explanation and at the same time treat the aerodynamic content in depth. Perhaps one exists, but I have not come across it as yet. I would recommend that you you can go for a book like &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0073398101&quot; rel=&quot;nofollow&quot;&gt;Fundamentals of Aerodynamics&lt;/a&gt; by John D. Anderson, Jr., and simultaneously refer to a mathematics book which will give you the necessary background knowledge. There are plenty of books which can serve this purpose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anderson's book, meanwhile, presents the material in a manner which is quite easy to understand, and build a strong foundation of aerodynamics and its applications. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you feel reading a mathematics book might take away a significant quantity of your time, another book I would recommend is &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0582026989&quot; rel=&quot;nofollow&quot;&gt;Flight Without Formulae&lt;/a&gt; by A.C.Kermode. It is a classic book on aeronautical engineering, and covers the various aerodynamic phenomena over a wing. In my view, it is quite apt for a beginner.&lt;/p&gt;&#xA;" OwnerUserId="189" LastActivityDate="2014-11-29T20:04:15.450" CommentCount="0" CommunityOwnedDate="2014-11-29T20:04:15.450" ContentLicense="CC BY-SA 3.0" />
  <row Id="9939" PostTypeId="2" ParentId="9872" CreationDate="2014-11-30T04:03:11.033" Score="2" Body="&lt;p&gt;According to our finite element analysis (US patent application 11/517915 (Akhmeteli, Gavrilin, Layered Shell Vacuum Balloons, you can find it at USPTO site or at &lt;a href=&quot;http://akhmeteli.org/wp-content/uploads/2011/08/vacuum_balloons_cip.pdf&quot; rel=&quot;nofollow&quot;&gt;http://akhmeteli.org/wp-content/uploads/2011/08/vacuum_balloons_cip.pdf&lt;/a&gt; ), it is possible to construct a vacuum balloon using commercially available materials and sandwich structures. In his comment, @Hugh refers to a Wikipedia article that emphasizes our calculation proving that one cannot make a vacuum balloon as a &lt;em&gt;homogeneous&lt;/em&gt; spherical shell made of currently available materials, but does not clearly quote our conclusion on a possibility of &lt;em&gt;inhomogeneous&lt;/em&gt; (sandwich structure) spherical shell vacuum balloon.&lt;/p&gt;&#xA;" OwnerUserId="4402" LastActivityDate="2014-11-30T04:03:11.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9940" PostTypeId="1" AcceptedAnswerId="9949" CreationDate="2014-11-30T05:19:25.773" Score="17" ViewCount="20779" Body="&lt;p&gt;I have read that it increases thrust and reduces noise. Is there a downside to this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bGDn6.jpg&quot; alt=&quot;E-Fan aircraft in flight&quot;&gt;&#xA;(Image source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Airbus_E-Fan_%2814088845198%29.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="1696" LastEditDate="2015-07-16T14:30:11.913" LastActivityDate="2017-10-19T06:44:57.137" Title="What are the advantages and disadvantages of ducted fans in designs such as the Airbus E-Fan?" Tags="&lt;aircraft-design&gt;&lt;electric-engine&gt;&lt;e-fan&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9942" PostTypeId="1" AcceptedAnswerId="9943" CreationDate="2014-11-30T11:55:45.727" Score="20" ViewCount="4122" Body="&lt;p&gt;Sharks and whales have them in the middle of their body, so why not planes?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="247" LastEditDate="2015-01-27T16:23:36.803" LastActivityDate="2020-08-30T21:26:51.193" Title="Why are vertical stabilizers always at the rear of an airplane?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9943" PostTypeId="2" ParentId="9942" CreationDate="2014-11-30T12:04:14.663" Score="30" Body="&lt;p&gt;With sea creatures the dorsal fin acts as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Keel&quot;&gt;keel&lt;/a&gt; providing the actual sideways force during the turn. They remain level while turning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes on the other hand bank to turn where the sideways force is provided by the lift of the wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To provide yaw stability the vertical stabilizer should be as far from the center of mass as possible. They are not in front because that would be unstable as the minor deviation from straight ahead would increase the force into the deviation rather than provide a force to counteract it.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-11-30T14:30:20.860" LastActivityDate="2014-11-30T14:30:20.860" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9944" PostTypeId="2" ParentId="9942" CreationDate="2014-11-30T15:17:09.817" Score="10" Body="&lt;p&gt;The vertical stabilizer is for &quot;stability&quot;. By having it aft of the center of gravity, it will generate a side force that will correct out any undesired yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try throwing a paper airplane or a dart backwards, and watch how it flips around due to this stabilizing force to have the stabilizer in the rear.&lt;/p&gt;&#xA;" OwnerUserId="4405" LastEditorUserId="65" LastEditDate="2014-11-30T23:33:06.277" LastActivityDate="2014-11-30T23:33:06.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9945" PostTypeId="1" AcceptedAnswerId="9959" CreationDate="2014-11-30T16:56:35.640" Score="13" ViewCount="3343" Body="&lt;p&gt;I have a private pilot license with airplane single engine land and instrument ratings. I'm about to get the commercial with a airplane multi engine land class rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I'm not currently flying for hire and my second class medical is more than a year old, so I cannot exercise my commercial privileges. Can I then legally fly a multi-engine plane exercising my private privileges, carrying, say, a friend or other non-paying passengers in a part-91 operation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, does the class-rating propagate down to my private?&lt;/p&gt;&#xA;" OwnerUserId="577" LastEditorUserId="19" LastEditDate="2017-11-06T14:53:31.033" LastActivityDate="2017-11-06T14:53:31.033" Title="Does a multi-engine rating propagate down from commercial to private?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;&lt;multi-engine&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9948" PostTypeId="2" ParentId="3864" CreationDate="2014-12-01T03:22:24.193" Score="9" Body="&lt;p&gt;That is how chapter 11 of the book begins. IMHO,  I suspect it was a rhetorical statement. For he then spends the rest of the chapter explaining what rudders are used for in aircraft and he contrasts this by giving an example, as a thought exercise, of how it could be done without a rudder.  One needs to read the whole chapter and the context the writer comes from rather than just use a sentence in isolation. Having said all this, the author is entitled to his opinion and to have that critically examined, which he does anyway.&lt;/p&gt;&#xA;" OwnerUserId="4414" LastEditorUserId="9276" LastEditDate="2016-05-27T11:28:58.927" LastActivityDate="2016-05-27T11:28:58.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9949" PostTypeId="2" ParentId="9940" CreationDate="2014-12-01T03:52:04.380" Score="16" Body="&lt;p&gt;An answer to your question can be found &lt;a href=&quot;https://aviation.stackexchange.com/questions/735/induced-drag-on-the-prop-and-prop-wing-lets/8796#8796&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Advantages of ducted fans would be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;reduced noise&lt;/li&gt;&#xA;&lt;li&gt;Better containment of broken blades&lt;/li&gt;&#xA;&lt;li&gt;protection of ground personnel when the engine is running&lt;/li&gt;&#xA;&lt;li&gt;Smaller size than a comparable propeller&lt;/li&gt;&#xA;&lt;li&gt;They look like a fancy jet engine. This is probably the main motivation of Airbus for their use on the E-Fan.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For almost all aircraft designers, their drawbacks have weighed more heavily:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less efficiency, because a smaller &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;mass of air&lt;/a&gt; is used for propulsion&lt;/li&gt;&#xA;&lt;li&gt;Additional friction drag and weight from the shroud&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The highest propulsion efficiency is possible with a large, slow-spinning prop. Once flight speeds approach the speed of sound, the propeller has to become smaller to avoid supersonic propeller tips, and then the shrouded design becomes more attractive. Electric airplanes so far are not fast enough to profit from this effect. I would be very skeptical of the increased thrust claim - both efficiency and thrust of the E-Fan ducted fans are lower than what a well-designed propeller can offer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The addition of the shroud only increases thrust when compared to the naked fan, but the fan is a poor replacement for a decent propeller at low speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-19T06:44:57.137" LastActivityDate="2017-10-19T06:44:57.137" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="9950" PostTypeId="2" ParentId="1418" CreationDate="2014-12-01T04:03:24.607" Score="1" Body="&lt;p&gt;A stall is when there is not enough air flowing over the wings to achieve the amount of lift necessary to keep the airplane flying. The telltale sign of an impending stall is when the airplane begins to buffet. The recovery procedure includes unloading the airframe by pushing forward on the yoke(the airplane equivalent of a steering wheel) and adding engine power. In a stall where the airplane's weight and balance is well configured, the nose will be heavier and will come down once the wings have stalled, making it easier for the pilot to recover even if the tailplane is not super effective after the stall. Unrecoverable stalls result when there is an aft Center of Gravity, and there is not enough authority in the elevator to force the nose down. &lt;/p&gt;&#xA;" OwnerUserId="4415" LastActivityDate="2014-12-01T04:03:24.607" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9952" PostTypeId="2" ParentId="9931" CreationDate="2014-12-01T15:06:47.553" Score="11" Body="&lt;p&gt;Unmanned balloons can indeed create a safety risk for aircraft. An aircraft could collide with the balloon itself (as described in &lt;a href=&quot;http://avherald.com/h?article=4694c940&quot;&gt;the case&lt;/a&gt; that Jan Hudec posted in his comment), or with the balloon's payload (see the FAA's AIM &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0705.html&quot;&gt;section 7-5-4&lt;/a&gt; for general comments on this).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But it's important to note that unmanned balloons are (or should be) launched only after appropriate preparation and communication; most countries have some sort of regulations to follow. In the US (for example), &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:2.0.1.3.15#sp14.2.101.d&quot;&gt;14 CFR 101&lt;/a&gt; governs unmanned balloon launches and it includes the following requirements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Launches must be in (mostly) clear skies and away from airports and built-up areas&lt;/li&gt;&#xA;&lt;li&gt;The balloon must have a radar reflector and lights (if launched at night)&lt;/li&gt;&#xA;&lt;li&gt;ATC must be informed in advance of the balloon launch, expected path etc.&lt;/li&gt;&#xA;&lt;li&gt;The operator must track the balloon's position and descent and report them to ATC as needed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In other words, the balloon should be as visible as possible - both visually and on radar - and ATC should know where it is. That gives pilots a way to see and avoid the balloon and ATC can provide warnings and/or avoidance instructions to aircraft directly where possible, which is actually fairly similar to how aircraft avoid other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there may be cases where someone launches a balloon without following those rules (or the local equivalents in another country). That would create a much higher safety risk but it would be illegal and the operator would be risking penalties for doing it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-01T15:06:47.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9953" PostTypeId="1" AcceptedAnswerId="9954" CreationDate="2014-12-01T15:09:56.357" Score="6" ViewCount="921" Body="&lt;p&gt;To which regulating authority's regulations and standards are large sub-sonic transport aircraft (passenger or cargo) designed? The FAA's, or EASA's, or both?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="62" LastEditDate="2014-12-01T15:25:44.060" LastActivityDate="2014-12-01T18:29:16.013" Title="Which authority regulates airliner design?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9954" PostTypeId="2" ParentId="9953" CreationDate="2014-12-01T16:21:46.387" Score="7" Body="&lt;p&gt;The safe operations of an aircraft is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Airworthiness&quot; rel=&quot;nofollow&quot;&gt;airworthiness&lt;/a&gt;. It is the standard by which an aircraft is determined fit to fly. Responsibility of airworthiness lies with national aviation regulatory bodies, manufacturers, as well as owners and operators. International standards are dictated by &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization&quot; rel=&quot;nofollow&quot;&gt;ICAO&lt;/a&gt; during the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_design_process&quot; rel=&quot;nofollow&quot;&gt;aircraft design process&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The International Civil Aviation Organization sets international&#xA;  standards and recommended practices for national authorities to base&#xA;  their regulations on&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA has &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Aviation_Regulations&quot; rel=&quot;nofollow&quot;&gt;regulations&lt;/a&gt; governing all aviation activities in the US. &lt;strike&gt;EASA also has airworthiness &lt;a href=&quot;http://en.wikipedia.org/wiki/European_Aviation_Safety_Agency#EASA_Part-M:_Continuing_Airworthiness&quot; rel=&quot;nofollow&quot;&gt;regulations&lt;/a&gt;.&lt;/strike&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to your question is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft manufacturer makes sure that the aircraft meets existing&#xA;  design standards, defines the operating limitations and maintenance&#xA;  schedules and provides support and maintenance throughout the&#xA;  operational life of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-01T17:14:01.360" LastActivityDate="2014-12-01T17:14:01.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9955" PostTypeId="1" CreationDate="2014-12-01T17:11:37.737" Score="8" ViewCount="4541" Body="&lt;p&gt;I am confused by this idea. If a flow is steady, its streamlines are unchanging. Taking the typical example of an airfoil, there is (at least) one streamline which will hit the leading edge of the airfoil and stagnate. &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Stagnation_point&quot; rel=&quot;noreferrer&quot;&gt;Stagnation point&lt;/a&gt;&lt;/strong&gt; is defined as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a point in a flow field where the local velocity of the fluid is zero.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WLfji.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now my question is, if the velocity here is zero, and fluid particles that pass through the streamline which results in a stagnation point have &lt;strong&gt;nonzero velocity&lt;/strong&gt; upstream, where do these fluid particles go? Since they are on the streamline, they have to reach the stagnation point? Does this not defy the &lt;strong&gt;conservation of mass&lt;/strong&gt; law? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, an online Fluid Mechanics course I have been following has in one lecture shown &lt;strong&gt;streamlines going away from the stagnation point&lt;/strong&gt;. If the velocity at this point is precisely zero (and is unchanging since the flow is steady), then how can the fluid particles go in other directions? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I must be missing something, do enlighten me. &lt;/p&gt;&#xA;" OwnerUserId="4387" LastEditorUserId="65" LastEditDate="2014-12-01T17:23:37.387" LastActivityDate="2015-08-05T13:53:37.913" Title="Can a steady flow have stagnation points?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;airfoil&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9956" PostTypeId="2" ParentId="9860" CreationDate="2014-12-01T18:23:23.160" Score="0" Body="&lt;p&gt;Firstly, the drag on an airship is very large, considering its large volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, they are slow and most of the volume is taken up by air/gases like helium etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, they are much slower than other modes of air transport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, an interesting project under development is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Worldwide_Aeros_Corp&quot; rel=&quot;nofollow&quot;&gt;Aeroscraft&lt;/a&gt;, which is an airship.&lt;/p&gt;&#xA;" OwnerUserId="189" LastActivityDate="2014-12-01T18:23:23.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9957" PostTypeId="2" ParentId="9953" CreationDate="2014-12-01T18:24:28.927" Score="1" Body="&lt;p&gt;In the USA, the FAA regulates airworthiness. For transport category aircraft, such as Boeing and Airbus, the regulations are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.11&quot; rel=&quot;nofollow&quot;&gt;14 CFR Part 25&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2014-12-01T18:29:16.013" LastActivityDate="2014-12-01T18:29:16.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9958" PostTypeId="2" ParentId="9955" CreationDate="2014-12-01T19:00:50.787" Score="14" Body="&lt;p&gt;The idea of a stagnation point is an idealization. This point is infinitesimally small, and air particles flowing along a streamline which leads into it will slow down on their way. The closer they come to the stagnation point, the slower they flow, and in the end they never arrive at the stagnation point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, air molecules have a finite size, so they flow either above or below the stagnation point streamline. Even if one particle manages to arrive at the stagnation point and stays in place (which is not possible in theory), a small angle of attack change will wash it away in the next moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One streamline goes away from the rear stagnation point which is located in the trailing edge. This point is doubly idealized, because it requires inviscid flow to have a rear stagnation point. Again, molecules flowing along the wall of the airfoil will be slowed down by the stagnation point pressure the closer they are to the trailing edge. Since they arrive either above or below the rear stagnation point, they will accelerate once they have passed the point of highest pressure and move on above or below the streamline emanating from the rear stagnation point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept of a stagnation point is really helpful for understanding flow phenomena, however. There is really a line (in 3D it is a plane) which separates air that will flow over the wing from that which will flow below it. This line changes with angle of attack, and the simple stall warning vane is based on this principle. Once the line ends below the vane, air will press it upwards, closing an electrical contact which activates a buzzer in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MnKr6.jpg&quot; alt=&quot;Aircraft&amp;#39;s leading edge with stall warning vane&quot;&gt;&#xA;Stall warning vane (small metal thingy sticking out from the wing)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-14T20:03:09.090" LastActivityDate="2015-05-14T20:03:09.090" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9959" PostTypeId="2" ParentId="9945" CreationDate="2014-12-01T19:17:10.273" Score="3" Body="&lt;p&gt;Note &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/daa4c54debeb6dca86256f3400626ab0/15c90b07303160f48625793b0068f317!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 61.31(c)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Aircraft category, class, and type ratings: Limitations on the&#xA;  carriage of persons, or operating for compensation or hire. Unless a&#xA;  person holds a category, class, and type rating (if a class and type&#xA;  rating is required) that applies to the aircraft, &lt;strong&gt;that person may not&#xA;  act as pilot in command of an aircraft that is carrying another&#xA;  person&lt;/strong&gt;, or is operated for compensation or hire. That person also may&#xA;  not act as pilot in command of that aircraft for compensation or hire.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since you will have the Category and Class rating, then you may carry another person.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your old license says:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Private Pilot&#xA;Airplane Single-engine Land&#xA;Instrument Airplane&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Your new license will say:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Commercial Pilot  &#xA;Airplane Multi-engine Land  &#xA;Instrument Airplane   &#xA;&#xA;Private Privileges  &#xA;Airplane Single-engine Land  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;You may fly under part 91 ASEL, AMEL, and IFR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may fly part 119 or 135 (or other commercial operations) AMEL and IFR&lt;sup&gt;1&lt;/sup&gt;. You may NOT fly part 119 or 135 or any commercial operations ASEL. If you want to fly ASEL in a commercial operation, you will need to upgrade your ASEL by passing another commercial checkride in an ASEL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the back of my certificate. I took the ASES checkride when I had a Private certificate.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6cfLi.jpg&quot; alt=&quot;Sample Certificate&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;HR&gt;&#xA;1. Assuming you have the correct medical and any other checkouts you may need&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-18T18:17:08.530" LastActivityDate="2014-12-18T18:17:08.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9960" PostTypeId="1" AcceptedAnswerId="9963" CreationDate="2014-12-01T20:25:42.623" Score="2" ViewCount="340" Body="&lt;p&gt;Can anyone suggest some ballpark figures for estimating the tracking accuracy of &lt;a href=&quot;http://en.wikipedia.org/wiki/ASDE-X&quot; rel=&quot;nofollow&quot;&gt;ASDE-X systems&lt;/a&gt; at airports? Specifically, I'm trying to get a sense of the error (± x meters) that can be expected from ASDE-X when fixing the position of an aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4422" LastEditorUserId="62" LastEditDate="2014-12-01T21:14:00.010" LastActivityDate="2014-12-01T21:36:22.147" Title="What is the approximate accuracy of ASDE-X?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9961" PostTypeId="1" AcceptedAnswerId="9964" CreationDate="2014-12-01T20:42:37.423" Score="9" ViewCount="2054" Body="&lt;p&gt;I'm a relative novice when it comes to aircraft performance and was wondering if someone could both answer the following and maybe direct me to some good source material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I wanted to model a take-off roll, can I assume a constant acceleration up until the wheels-up point?  If not constant, is there a reasonably good function that could model the velocity curve on takeoff?&lt;/p&gt;&#xA;" OwnerUserId="4422" LastEditorUserId="97" LastEditDate="2015-04-22T00:40:07.937" LastActivityDate="2015-04-22T00:40:07.937" Title="Does acceleration increase linearly on a takeoff roll?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9963" PostTypeId="2" ParentId="9960" CreationDate="2014-12-01T21:36:22.147" Score="5" Body="&lt;p&gt;The FAA has &lt;a href=&quot;https://www.faa.gov/search/?omni=MainSearch&amp;amp;q=asde-x&quot;&gt;a bunch of information&lt;/a&gt; on ASDE-X, most of which I personally have no idea how to interpret correctly. The &lt;a href=&quot;https://faaco.faa.gov/attachments/153CAB60-EF5B-74EF-207588DC9BA9FA65.doc&quot;&gt;ASDE-X procurement specification&lt;/a&gt; in particular has a lot of technical details on radar performance and although I didn't understand much of it I did notice this requirement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;3.6.3   Map Registration&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The display of target data shall [R306] be registered to the display map with an accuracy of at least 20 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So whatever the &lt;em&gt;technical&lt;/em&gt; capabilities of the system are, &lt;em&gt;operationally&lt;/em&gt; it seems that you can assume it's accurate to within 20ft, which seems to be reasonable in the context of large aircraft. You may be able to get more out of the documentation than I could, of course.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-01T21:36:22.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9964" PostTypeId="2" ParentId="9961" CreationDate="2014-12-01T23:06:10.823" Score="8" Body="&lt;p&gt;Thrust depends on speed and the type of engine. To simplify things, we can say that thrust changes over speed in proportion to the expression $v^{n_v}$ where $n_v$ is a constant which depends on engine type. Piston aircraft have constant power output, and thrust is inverse with speed over the speed range of acceptable propeller efficiencies, hence $n_v$ becomes -1 for piston aircraft. Turboprops make some use of ram pressure, so they profit a little from flying faster, but not much. Their $n_v$ is -0.8 to -0.6. Turbofans are better in utilizing ram pressure, and their $n_v$ is -0.5 to -0.2. The higher the bypass ratio, the more negative their $n_v$ becomes. Jets (think J-79 or even the old Jumo-004) have constant thrust over speed, at least in subsonic flow. Their $n_v$ is approximately 0. Positive values of $n_v$ can be found with ramjets - they develop more thrust the faster they move through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag depends also on speed, and in addition on lift. During the takeoff roll the dynamic pressure grows with the square of speed, and drag is almost proportional to the dynamic pressure. Since the flow's &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number&lt;/a&gt; also increases with speed, the zero-lift drag coefficient (aka friction plus pressure drag coefficient) decreases with speed. Depending on the ground attitude of the aircraft it will create already some lift during the rolling phase, but lift substantially increases during rotation when it is raised to lift the aircraft off the ground. When the aircraft accelerates further after liftoff, the lift-dependent part of drag goes down with speed while the zero-lift part continues to increase with dynamic pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most aircraft, thrust is highest when the aircraft is at rest (constant pitch propellers can have a lousy efficiency at takeoff when they are optimized for fast flight, so here you might have higher thrust at some positive speed), and decreases the faster the aircraft moves through air. Since drag is also lowest with the aircraft at rest, the highest acceleration is possible right after brake release. As soon as the aircraft rotates, the new lift-dependent drag component will cause a marked decrease in acceleration, and when the aircraft climbs, some of the excess thrust needs to go into climbing, so acceleration decreases again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newton's first law gives a formula for acceleration a: $$a = \frac{T - D}{m}$$&#xA;where T is thrust, D is drag and m is the mass of the aircraft. The integration of acceleration over time gives speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no single formula for the velocity curve, and my recommendation is to split the take-off into three sections: Ground roll, rotation and initial climb. In all phases you need to calculate with speed-depependent drag and thrust, so it will be best to integrate the parameters stepwise in small time steps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The comments encouraged me to give a more detailed list of drag components. These here have to be considered during the take-off roll:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Zero-lift drag of the airframe (due to friction and pressure)&lt;/li&gt;&#xA;&lt;li&gt;Induced (lift-related) drag for the aircraft in horizontal attitude, including reduction due to ground effect&lt;/li&gt;&#xA;&lt;li&gt;Drag increment due to flaps in take-off position&lt;/li&gt;&#xA;&lt;li&gt;Landing gear drag&lt;/li&gt;&#xA;&lt;li&gt;Wheel friction (0.025 * weight on a hard runway, but a lot more on soft ground)&lt;/li&gt;&#xA;&lt;li&gt;Kinetic energy loss or gain due to runway slope&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With rotation onset these drag components must be added:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Trim drag due to elevator deflection to lift the nose&lt;/li&gt;&#xA;&lt;li&gt;Induced drag at the actual pitch angle&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When the aircraft lifts off, these changes must be considered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reduced power for acceleration due to power requirement for climb&lt;/li&gt;&#xA;&lt;li&gt;No more wheel friction&lt;/li&gt;&#xA;&lt;li&gt;When the gear is retracted, drag increases as the doors open and is greatly reduced once all wheels are stowed.&lt;/li&gt;&#xA;&lt;li&gt;Ground effect is reduced as the aircraft climbs away from the ground&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Don't forget to include wind speed in your calculation!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-02T20:16:28.767" LastActivityDate="2014-12-02T20:16:28.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9965" PostTypeId="1" AcceptedAnswerId="9969" CreationDate="2014-12-02T00:22:22.217" Score="13" ViewCount="682" Body="&lt;p&gt;The FAA/CAMI imposes certain testing requirements on transgender pilots, listed in the Guide for Aviation Medical Examiners under &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item41/amd/grs/&quot; rel=&quot;noreferrer&quot;&gt;Item 41 (G-U System), subheading &quot;Gender Identity Disorder&quot;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the FAA the only authority that has these requirements, or do other countries have similar policies?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;the link above is broken but I think there might be value leaving the old URL in case people want to try to get there on archive.  The updated reg is at &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item48/amd/gd/&quot; rel=&quot;noreferrer&quot;&gt;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item48/amd/gd/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3146" LastEditorUserId="3146" LastEditDate="2016-01-28T04:30:54.667" LastActivityDate="2016-01-28T04:30:54.667" Title="Is the FAA the only authority with specific medical requirements for transgender pilots?" Tags="&lt;pilot-certification&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9967" PostTypeId="2" ParentId="9860" CreationDate="2014-12-02T10:01:15.587" Score="7" Body="&lt;p&gt;On the subject of &quot;port calls&quot; to unimproved areas:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know what sort of effect modern technologies (computer autopilots, vectored-thrust engines) would have, but ground handling of Hindenburg-class airships in the 1930s was &lt;em&gt;extremely&lt;/em&gt; labor-intensive.  Landing the &lt;em&gt;Hindenburg&lt;/em&gt; or &lt;em&gt;Graf Zeppelin&lt;/em&gt; required a crew of several hundred to guide it to a mooring mast, and even after mooring, the airship was still somewhat &quot;in flight&quot;, requiring a skeleton crew to maintain balance and prevent &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Zr3nearvertical.jpg&quot;&gt;an incident like this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airship can't just &quot;set down&quot; anywhere.  At a bare minimum, you need a mooring mast to keep it from blowing away, and a cleared area around that mast large enough for the airship to swing around with the wind.  For something the size of the Hindenburg, that's a circle a half-kilometer across.  The proposals for using airships for heavy-cargo delivery to remote areas presume that a ground crew is able to reach the area in advance to prepare for the landing.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-12-02T10:01:15.587" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9968" PostTypeId="1" CreationDate="2014-12-02T14:15:11.933" Score="2" ViewCount="620" Body="&lt;p&gt;(This is a repost of &lt;a href=&quot;https://movies.stackexchange.com/q/14441&quot;&gt;this question on Movies SE&lt;/a&gt;. I hope to get better answers here.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Irene Adler shows the following text to Sherlock:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;007 Confirmed allocation&#xA;4C12C45F13E13G60A60B61F34G34J60D12H33K34K&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;He immediately guesses that &quot;these are seat allocations on a passenger jet&quot;, claims it must be a Boeing 747 and then recalls a specific flight which takes off at 6:30 PM the next day. Note that only 14 seats are listed. A Boeing 747 can carry about four hundred passengers. The flight takes off tomorrow evening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do airlines really document or communicate seating allocations in this way? Shouldn't there be more seats &quot;confirmed&quot; (whatever that means)?&lt;/p&gt;&#xA;" OwnerUserId="2759" LastEditorUserId="-1" LastEditDate="2017-04-13T12:54:04.060" LastActivityDate="2014-12-02T19:45:09.220" Title="Is the &quot;confirmed allocation&quot; string in &quot;A Scandal in Belgravia&quot; a real airline practice?" Tags="&lt;airline-operations&gt;&lt;boeing-747&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-12-03T09:37:15.793" ContentLicense="CC BY-SA 3.0" />
  <row Id="9969" PostTypeId="2" ParentId="9965" CreationDate="2014-12-02T15:51:09.727" Score="13" Body="&lt;p&gt;As several commenters have noted, medical rules are different in each country. ICAO provides guidelines and recommendations, but it's up to each country to actually implement them. ICAO's personnel licensing requirements are in Annex 1 which is &lt;a href=&quot;http://www.icao.int/safety/airnavigation/pages/peltrgfaq.aspx#anchor02&quot;&gt;not freely available&lt;/a&gt; but their &lt;em&gt;&lt;a href=&quot;http://www.icao.int/publications/Documents/8984_cons_en.pdf&quot;&gt;Manual of Civil Aviation Medicine&lt;/a&gt;&lt;/em&gt; implies that transgender pilots should be considered 'higher risk':&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Applicants with disorders of behaviour (for example regarding habit,&#xA;  gender identity, sexuality) should be assessed on the basis of their&#xA;  ability to put aside the disorder (or any conflicts related to the&#xA;  disorder) in order to attend to the aviation task at hand. These&#xA;  persons may have significant conflicts with their environment, leading&#xA;  to further difficulties, which may become an impediment for them to&#xA;  hold an aviation licence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Looking at specific countries, the FAA may be an unusual case by explicitly mentioning gender identity issues. I couldn't find any mention of them in the &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/AMC%20and%20GM%20on%20the%20medical%20certification%20of%20pilots%20and%20medical%20fitness%20of%20cabin%20crew.pdf&quot;&gt;EASA&lt;/a&gt;, &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/regserv/cars/part4-standards-t42402-1412.htm&quot;&gt;Canadian&lt;/a&gt; or &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=2499&amp;amp;pagetype=90&amp;amp;pageid=13769&quot;&gt;UK&lt;/a&gt; medical requirements. But all countries' medical requirements include something general like this (this example is from EASA):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(g) Personality or behavioural disorder Where there is suspicion or&#xA;  established evidence that an applicant has a personality or&#xA;  behavioural disorder, the applicant should be referred for psychiatric&#xA;  opinion and advice.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That catch-all clause would - I assume - include &lt;a href=&quot;http://en.wikipedia.org/wiki/Gender_identity_disorder&quot;&gt;gender identity disorder&lt;/a&gt; and therefore require psychiatric evaluation of the pilot. And in cases where a pilot has had gender reassignment surgery and/or drug treatment, the surgery and drugs regimen would almost certainly trigger additional testing and investigation (so would any other major surgical procedure or long-term drug treatment).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, it's worth noting that whatever the general rules are, every case is different and the only way to get a specific answer for an individual is to consult with an aviation medical examiner for that jurisdiction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Disclaimer: I know nothing about medicine except that it's complicated. Consult an aviation medical specialist if you want a real answer.)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-03T03:27:44.760" LastActivityDate="2014-12-03T03:27:44.760" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9970" PostTypeId="2" ParentId="3864" CreationDate="2014-12-02T18:49:26.327" Score="2" Body="&lt;p&gt;I don't think he every changed his mind because the statement, and the enclosing chapter, is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Proof_by_contradiction&quot; rel=&quot;nofollow&quot;&gt;proof by contradiction&lt;/a&gt;. Assume the contradiction (&quot;Planes don't need rudders!&quot;) then go on to show why they do, and therefore the assumption must be false. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-02T18:49:26.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9971" PostTypeId="2" ParentId="9968" CreationDate="2014-12-02T19:04:28.713" Score="1" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on my research for string &lt;code&gt;confirmed allocation&lt;/code&gt;, there were no references found related to airlines or their practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the background scenario about the conversation Sherlock was having, something like the following had happened (references: &lt;a href=&quot;http://www.avclub.com/tvclub/sherlock-a-scandal-in-belgravia-73493&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://take-your-vitamins.blogspot.com/2013/07/sherlock-puzzle-series-2-episode-1-this.html&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://www.tvrage.com/Sherlock/episodes/1064974314/recap&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://youranswers.info/question/view/en/YUhSMGNEb3ZMMjF2ZG1sbGN5NXpkR0ZqYTJWNFkyaGhibWRsTG1OdmJTOXhkV1Z6ZEdsdmJuTXZNVFEwTkRFdmQyaGhkQzFsZUdGamRHeDVMV2x6TFhSb1pTMWhiSEJvWVc1MWJXVnlhV010YzNSeWFXNW5MV2x1TFdFdGMyTmhibVJoYkMxcGJpMWlaV3huY21GMmFXRT0=&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://arianedevere.livejournal.com/26848.html?thread=275680&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(my paraphrasing, not actually a quote)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sherlock knows that 007 is a flight of &lt;em&gt;Bond Air&lt;/em&gt; which is leaving for&#xA;  Baltimore tomorrow at 6:30pm. He is aware of a terrorist plot of&#xA;  having dead bodies on an airplane (14 seats allocations) so that no one actually dies. The&#xA;  first 0 in flight number indicates that zero causalities will happen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;P.S.: This question is not about aviation but movies.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-02T19:45:09.220" LastActivityDate="2014-12-02T19:45:09.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9972" PostTypeId="1" AcceptedAnswerId="9973" CreationDate="2014-12-02T21:38:46.643" Score="12" ViewCount="1857" Body="&lt;p&gt;I was watching &lt;a href=&quot;http://en.wikipedia.org/wiki/Agents_of_S.H.I.E.L.D.&quot; rel=&quot;noreferrer&quot;&gt;Agents of Shield&lt;/a&gt; recently, and in it the team fly a plane that's claimed to be a modified &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot; rel=&quot;noreferrer&quot;&gt;C-17 Globemaster&lt;/a&gt;. It has two extra engines, rotary turrets, and, according to the wiki, a pair of half-length wings at the rear of the fuselage, seen here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jfwsZ.jpg&quot; alt=&quot;the SHIELD modified Globemaster&quot;&gt;(image courtesy of &lt;a href=&quot;http://agentsofshield.wikia.com/wiki/File:084-002.png&quot; rel=&quot;noreferrer&quot;&gt;Agents of SHIELD wiki&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me, it also kind of looks like a second horizontal stabilizer. Certainly some of the modifications to this fictional plane are pure flights of fancy, but is there any basis behind this one? Is there any reason why this feature would be useful? Have there possibly been any experimental or production aircraft with something like this? Or is this pure &quot;cool factor,&quot; with no real basis in aviation?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="19" LastEditDate="2017-01-30T15:56:30.983" LastActivityDate="2020-03-23T11:59:22.493" Title="Are there cases where a double horizontal stabilizer is useful?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="5" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="9973" PostTypeId="2" ParentId="9972" CreationDate="2014-12-02T22:45:18.100" Score="12" Body="&lt;p&gt;The main aerodynamic purpose of the horizontal stab (or certain &lt;a href=&quot;http://en.wikipedia.org/wiki/Canard_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;canards&lt;/a&gt;) is to provide &lt;a href=&quot;http://en.wikipedia.org/wiki/Longitudinal_static_stability&quot; rel=&quot;noreferrer&quot;&gt;longitudinal stability&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the rear wing with the 5th and 6th engine flies &quot;up,&quot; like the main wing, then it will counteract the longitudinal stability of the horizontal stabilizer. If the rear wing flies down, like the h-stab, then it is just extraneous, since the h-stab can be made as large as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all you want to do is to add extra engines, they can be mounted on the main wing, like in the eight-engine B-52 bomber:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vd7Ck.jpg&quot; alt=&quot;B-52 Bomber&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or the six-engine Antonov An-225 cargo jet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gm4Nj.jpg&quot; alt=&quot;Anatov AN-225&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="22726" LastEditDate="2018-05-24T22:30:53.650" LastActivityDate="2018-05-24T22:30:53.650" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="9975" PostTypeId="1" AcceptedAnswerId="9976" CreationDate="2014-12-03T09:42:47.670" Score="9" ViewCount="3579" Body="&lt;p&gt;Recently my kids and I were denied access to our flight because we missed the check in window.  We were informed that new calculations would have had to have been made by the pilot, despite not having had any check in luggage.  When are these calculations made?  Before or after the passengers board?  Apparently, our names did not make the manifest in time, despite nobody having boarded the plane yet.  We were left stranded at the gate.  Can anybody explain the procedures regarding these calculations, because I cannot understand why we were not permitted to fly?&lt;/p&gt;&#xA;" OwnerUserId="4429" LastActivityDate="2018-09-02T21:54:17.680" Title="Do additional passengers impact on weight and balance of a domestic airliner?" Tags="&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="9976" PostTypeId="2" ParentId="9975" CreationDate="2014-12-03T12:13:18.503" Score="13" Body="&lt;p&gt;You're really asking two questions here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) What is the procedure (ie when are the calculations made)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Do additional passengers affect the weight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the procedure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As soon as check in closes, the numbers for passengers and bags is finalized - nothing else can be added to the plane, otherwise it could potentially run out of fuel. Passengers can be removed, but the captain must be informed in case it affects balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point the captain calculates the required information for weight, fuel, and balance. It's done shortly after check in closes as there is a limited window in which to add extra fuel etc - remember that the tanker needs to be long clear before the engines can be started and other departure checklists can be run.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is done so early because the pilot needs time to prepare the aircraft for departure, he doesn't have time to mess about later on adjusting the numbers, and if he has to re-calculate later it adds a whole extra area where mistakes can be made - especially since later on the pilot is likely to be more distracted. Doing it once is fairly easy, you plug the number of passengers into a set of sums along with temperature and other related factors, and it works fuel load out for you. If you try adding passengers you have to re-calculate this, then work out how much extra to add... it's just a whole bunch of extra things that can go wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do extra passengers affect the weight/balance of the aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer: yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take an A319 as an example aircraft: empty, it weighs 40,000 kg, up to a maximum of around 60,000kg&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have no idea what you and your family and bags weigh, but let's produce a range. Please don't be insulted by the range: the airline aren't judging your weight when deciding if you can board late: they have to have a single rule regardless of whether it's a skinny teenager travelling alone or a party of 15 obese people&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You're an adult, so you presumably weigh anywhere between 50 and 150kg &lt;/li&gt;&#xA;&lt;li&gt;You said children but don't state an age, so they could be newborns or adults: weight anywhere between 2kg and 150kg&lt;/li&gt;&#xA;&lt;li&gt;I don't know how many children you have, but for the sake of argument I'll guess it's between 2 and 5 (as you said &quot;children&quot;) - that's somewhere between 4 and 750kg&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So your total weight for a single family is anywhere between 54kg and 900kg. Chances are most families are more like 250-300kg (a couple of adults at 60-100kg each, and a couple of kids at 20-40kg), but airlines have to assume worst case, otherwise their check in staff have the impossible job of deciding who's too fat to board late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So take that worst-case scenario (6 obese people) and add a 7kg carry-on bag each, that's nearly 1000kg of weight which the pilot doesn't know on the plane. Or over 2% of the aircraft's empty weight and nearly 1.5% of the maximum takeoff weight. This is assuming they have no hold bags.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if your family only weighs 250kg between you and your bags, that's still nearly 0.5% of the aircraft's empty weight - a not insignificant number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And finally you have to remember that by carrying the extra 0.5% of weight in people, the aircraft needs some extra fuel. And a bit more fuel to carry that extra fuel, and both of those extra amounts of fuel change the balance of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most &quot;normal&quot; flights you aren't going to make a huge enough difference to balance to cause a crash, or change the fuel requirement enough to cause an issue, but if the aircraft had to divert, you could be the difference between running out of fuel or not, and in some worst-case circumstances a really big family could upset a small aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2014-12-03T12:39:07.040" LastActivityDate="2014-12-03T12:39:07.040" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9977" PostTypeId="2" ParentId="9972" CreationDate="2014-12-03T12:42:45.200" Score="4" Body="&lt;p&gt;Do they have a nefarious super-weapon in the rear of the fuselage? That could necessitate the extra lift and, more importantly, the shifting of that lift further back to keep the centre of lift near the centre of gravity. That would also explain the extra engines, as the extra power is needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also needs the extra engines to maintain the pretence of balance when performing VTOL maneuvers (although this would again suggest the weight has been heavily shifted backwards behind the &quot;regular&quot; wing)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, though, it's a bad design which wouldn't be the ideal way to handle any of those things - it's mostly for cool-factor.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-12-03T12:42:45.200" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9978" PostTypeId="2" ParentId="9975" CreationDate="2014-12-03T14:55:08.617" Score="9" Body="&lt;p&gt;The Advisory Circular &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-27E.pdf&quot; rel=&quot;nofollow&quot;&gt;&quot;AIRCRAFT WEIGHT AND BALANCE CONTROL&quot;&lt;/a&gt; (AC120-27E) describes one way in which passenger weights and baggage weights may be calculated by the airlines for various passenger populations, aircraft sizes and configurations, and season (summer or winter, because of the effects of density altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What may have happened is that they had already calculated W&amp;amp;B for the flight, loaded a certain amount of fuel for the passenger and cargo weight, flight plan, and weather, and didn't want to (or couldn't) recalculate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You didn't say what kind of aircraft you were flying on, but you should know that the smaller or lighter the airplane, the more sensitive it is to weight and balance. When I've flown on a Dash-8, a certain number of passengers had to be fore, abeam, and aft of the wing in order to maintain the center of gravity.  On a larger aircraft such as a 747, there is more flexibility with W&amp;amp;B. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-03T17:44:53.483" LastActivityDate="2014-12-03T17:44:53.483" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9979" PostTypeId="2" ParentId="3667" CreationDate="2014-12-03T15:09:13.847" Score="12" Body="&lt;p&gt;Yes. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_13&quot;&gt;14 CFR 61.3(b)&lt;/a&gt; covers this (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) &lt;em&gt;Required pilot certificate for operating a foreign-registered&#xA;  aircraft within the United States&lt;/em&gt;. No person may serve as a required&#xA;  pilot flight crewmember of a civil aircraft of foreign registry within&#xA;  the United States, unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) That person's pilot certificate or document issued under §61.29(e)&#xA;  is in that person's physical possession or readily accessible in the&#xA;  aircraft when exercising the privileges of that pilot certificate; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) &lt;strong&gt;Has been issued in accordance with this part&lt;/strong&gt;, or has been issued&#xA;  or validated by the country in which the aircraft is registered.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So a US license (i.e. one issued under part 61) is allowed as an alternative to a foreign license for operating the foreign aircraft. The other country could have rules on this too, but I have no idea if they would be enforceable (obviously, one country's laws are usually not valid in another one).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-03T15:09:13.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9980" PostTypeId="1" AcceptedAnswerId="9989" CreationDate="2014-12-03T16:29:51.377" Score="14" ViewCount="4314" Body="&lt;p&gt;Skyvector lists the gradient for &lt;a href=&quot;http://skyvector.com/airport/MCI/Kansas-City-International-Airport&quot;&gt;KMCI&lt;/a&gt; as 0.3%.  What is the rule of thumb for how large a gradient needs to be before you always take off downhill and always land uphill like they do at &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenzing-Hillary_Airport&quot;&gt;Lukla&lt;/a&gt;?  Assume winds are not a factor.&lt;/p&gt;&#xA;" OwnerUserId="4302" LastEditorUserId="1961" LastEditDate="2014-12-05T13:58:51.183" LastActivityDate="2014-12-05T13:58:51.183" Title="What is the rule of thumb for land/taking-off on a sloped runway?" Tags="&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9981" PostTypeId="1" AcceptedAnswerId="9986" CreationDate="2014-12-03T17:33:07.593" Score="32" ViewCount="12492" Body="&lt;p&gt;How does flying a biplane differ from flying a monoplane? Apart from the increased drag and lift, how does it handle differently, and what effect does that have on manoeuvring?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, I'm interested in differences between a biplane and a hypothetical &lt;em&gt;equivalent&lt;/em&gt; monoplane, not differences between vintage airplanes and modern ones, or differences between aerobatic and utility airplanes.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2018-04-02T11:32:14.363" Title="What special handling characteristics or techniques do biplanes have?" Tags="&lt;biplane&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9982" PostTypeId="2" ParentId="9980" CreationDate="2014-12-03T17:39:05.030" Score="2" Body="&lt;p&gt;There is no firm guideline. It depends on wind conditions and other factors like the surrounding terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have landed at &lt;a href=&quot;http://www.airnav.com/airport/KAFN&quot; rel=&quot;nofollow&quot;&gt;Jaffrey&lt;/a&gt; only uphill, which has a 0.9% grade and a bad surface, but people can and do land there downhill. It is very steep for an air strip. If the wind was strong enough I would have no problem landing downhill there, but with moderate winds I would always go uphill.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-12-03T17:39:05.030" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="9983" PostTypeId="2" ParentId="9981" CreationDate="2014-12-03T18:16:59.230" Score="24" Body="&lt;p&gt;In a nutshell, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Biplane#Advantages_and_disadvantages&quot; rel=&quot;noreferrer&quot;&gt;advantages and disadvantages&lt;/a&gt; are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Advantages&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Biplanes (or &lt;a href=&quot;http://en.wikipedia.org/wiki/Triplane&quot; rel=&quot;noreferrer&quot;&gt;triplanes&lt;/a&gt;) can usually lift up to 20% more than can a similarly sized monoplane of similar wingspan. A biplane will&#xA;  therefore typically have a shorter wingspan than the equivalent&#xA;  monoplane, which tends to afford greater maneuverability.&lt;/li&gt;&#xA;  &lt;li&gt;The struts and wire bracing of a typical biplane form a &lt;a href=&quot;http://en.wikipedia.org/wiki/Box_girder&quot; rel=&quot;noreferrer&quot;&gt;box girder&lt;/a&gt;. Particularly when divided into bays, this permits a very light but strong and rigid wing structure. This allows a biplane to fly with very little power...&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Disadvantages&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Each wing negatively interferes with the aerodynamics of the other, requiring greater overall surface area to produce the same lift as the&#xA;  equivalent monoplane.&lt;/li&gt;&#xA;  &lt;li&gt;A biplane typically also produces more drag than a monoplane, especially as speed increases.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LoTdh.gif&quot; alt=&quot;Comparison&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Technological Advancements&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In early days (1900-1930s), the biggest advantage of biplanes was having twice the surface area and a rigid structure to support the wings. But at present, high strength carbon fiber reinforced plastics made it possible to build very high aspect ratio wings without any (or little) external support. With the advent of steel, then aluminum air frames, the previous considerations were mute, and monoplanes have become more common than biplanes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;NASA has a historical &lt;a href=&quot;http://history.nasa.gov/SP-468/ch4-3.htm&quot; rel=&quot;noreferrer&quot;&gt;discussion&lt;/a&gt; about these.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-03T19:26:03.080" LastActivityDate="2014-12-03T19:26:03.080" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="9984" PostTypeId="2" ParentId="9981" CreationDate="2014-12-03T19:09:57.540" Score="4" Body="&lt;p&gt;Biplanes handle like bricks. They lose altitude more quickly at low speed, and they are much easier to stall. They have more drag and will enter a spin more readily. They are much more susceptible to cross winds than monoplanes and therefore can only take off and land in relatively moderate conditions, since they will flip over easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage they have is that they can turn much more quickly than a monoplane, so they are nowadays mainly used for acrobatics, like Pitts Specials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the war pilots flying Fairey Swordfishes and Fireflies were in great danger from the much faster Bf109s. They would escape by plummeting to the ocean in a virtual free fall then pulling out at the last moment. Any Messerschmidt pilot dumb enough to follow them in this maneover would be flying their last mission.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-12-03T19:09:57.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9985" PostTypeId="2" ParentId="9981" CreationDate="2014-12-03T19:33:30.563" Score="4" Body="&lt;p&gt;There is no principial difference in handling. Both have the same set of control surfaces and stability is achieved using the same methods, so the piloting techniques are the same. There will usually be difference in performance. Biplanes loose speed faster, but are slightly more manoeuvrable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of biplane is that it can be built with less strong materials, because the wings are shorter and the box girder bracing structure distributes the loads very well. This often meant lower weight which offset the increased drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantage of biplane is that shorter wingspan means lower aspect ratio and therefore higher induced drag, which dominates at low speed, and the larger frontal area and surface area (interference between the wings means they are less efficient than they would be independently) mean higher form drag, which dominates at high speed. So a biplane needs a stronger engine for the same weight and will not glide as far should the engine fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before cantilever (without bracing) wings were developed, the bracing didn't allow monoplanes to achieve that much lower drag and their higher weight cancelled the little aerodynamic advantage they had, so biplanes dominated. With cantilever wings the aerodynamic advantage of monoplanes became more important and biplanes almost disappeared.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few aerobatic biplanes (like the famous Pitts SC1) remained, most likely because with shorter wingspan they have lower moment of inertia in roll and therefore roll slightly more easily.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-12-03T22:37:13.790" LastActivityDate="2014-12-03T22:37:13.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9986" PostTypeId="2" ParentId="9981" CreationDate="2014-12-03T20:01:07.007" Score="25" Body="&lt;h2&gt;Short answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For clarification: Equivalence between biplane and monoplane means than both have the same wing area and the same engine. Then the main &lt;strong&gt;differences in maneuvering&lt;/strong&gt; are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The biplane has better roll acceleration than an equivalent monoplane.&lt;/li&gt;&#xA;&lt;li&gt;The biplane has a higher roll rate than an equivalent monoplane at the same speeds.&lt;/li&gt;&#xA;&lt;li&gt;All biplane flying takes place at lower speeds, resulting in a lower space requirement for all maneuvers. This also means that inertial effects are less pronounced: When pulling up, there is less kinetic energy available for climbing, so (for example) hammerhead turns will end with less altitude gain.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Differences in handling&lt;/strong&gt;: The biplane has&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;lower aileron forces for the same roll rate at the same speed&lt;/li&gt;&#xA;&lt;li&gt;lighter control forces overall due to lower flight speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Differences in performance&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;shorter take-off and landing distances&lt;/li&gt;&#xA;&lt;li&gt;a lower stall speed&lt;/li&gt;&#xA;&lt;li&gt;a much lower maximum speed&lt;/li&gt;&#xA;&lt;li&gt;a lower optimum cruise speed and range&lt;/li&gt;&#xA;&lt;li&gt;a lower power requirement due to the lower flying speeds, or if both use the same engine, a better power-to-weight ratio&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;when compared to an equivalent monoplane. These differences are most pronounced if the airplane carries just the pilot and not much payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying techniques are the same as for monoplanes. Indirectly, differences are likely due to differences in design. Example: Few biplanes profit from having a retractable landing gear while gear retraction makes sense for monoplanes with higher power loading (installed power relative to wing area).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Explanation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Biplanes have two major differences:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Smaller wing span at the same wing area, and&lt;/li&gt;&#xA;&lt;li&gt;Wire bracing results in very lightweight biplane wings.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The smaller span reduces roll damping and roll inertia, so a biplane will accelerate into a roll more quickly than an equivalent monoplane and will reach a higher roll rate. This is the main difference in maneuvering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The smaller wing span results in more induced drag if both have the same mass and the same speed. With wire bracing, this condition is unrealistic, and an equivalent biplane will be much lighter. If the structure is a substantial part of the aircraft's mass (this is typical for aerobatic airplanes), the result can easily be less induced drag, despite the lower span, and also lower wing loading. This in turn means that both fly at different speeds: The biplane will be able to fly much slower, but the aerodynamic drag of the bracing will restrict it to low speeds. This also means inertial effects are less pronounced: The lower mass &lt;strong&gt;and&lt;/strong&gt; lower speed of the biplane combine for a marked difference to the equivalent monoplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aerobatic displays this is ideal: All action takes place close to the audience, and the biplane will need a much smaller area for all maneuvers than an equivalent, but heavier monoplane. The downside are low maximum speed and low range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another difference in performance are much shorter take-off and landing distances due to the lower wing loading, which results in a lower stall speed. The optimum endurance and optimum range speeds are lower than those of an equivalent monoplane as well, so all biplane flying happens at lower speeds, which is beneficial for training aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since control forces are proportional to dynamic pressure, a biplane will have lower control forces than an equivalent monoplane. Here equivalence also means that the relative chord of all control surfaces is the same. In reality, a good designer will select a higher relative chord for the biplane's control surfaces to ensure that control forces are above their required minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The heavy, unreliable engines of the early years made biplanes the ideal way of taking to the air. Once engines became more powerful and allowed higher payloads, the monoplane became better suited to carrying passengers and freight at higher speeds and over longer distances.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-28T11:53:43.703" LastActivityDate="2016-02-28T11:53:43.703" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="9987" PostTypeId="2" ParentId="9980" CreationDate="2014-12-03T20:30:58.633" Score="6" Body="&lt;p&gt;I happened to be looking at some takeoff distance charts, so I looked into this. As Tyler says, the answer will depend on your airplane's performance. With good brakes and plenty of runway, a small plane may not care as much as a larger one. The following applies to the PC-12.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know you said to assume winds are not a factor, but it may help to roughly relate the effects of slope and wind. It turns out that 4% of slope will either help or hurt about the same amount as 10 kt of wind (within about 7%). Both provide around 10% benefit or 25% penalty on takeoff distance, and landing distance is affected by slope a bit less and wind a bit more. This would provide a good sense of how much a slope will affect the runway length you need. That penalty will certainly start to hurt as slope increases.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-12-03T20:30:58.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="9988" PostTypeId="1" AcceptedAnswerId="9993" CreationDate="2014-12-03T20:36:29.397" Score="4" ViewCount="1725" Body="&lt;p&gt;Given the overall pressure ratio of a multi-stage compressor, how can I calculate the increase in pressure at each stage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does pressure increase linearly at every stage, or does it increase logarithmically or exponentially?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intuition tells me that pressure increases logarithmically since the latter stages of a compressor can't compress the air as much as the first stages, but intuition hasn't served me so well in thermodynamics...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="4432" LastEditorUserId="4432" LastEditDate="2014-12-03T22:30:13.147" LastActivityDate="2019-10-26T17:42:12.213" Title="How does pressure increase in a multistage compressor?" Tags="&lt;jet-engine&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9989" PostTypeId="2" ParentId="9980" CreationDate="2014-12-03T20:45:19.757" Score="13" Body="&lt;p&gt;&lt;strong&gt;What does your POH/AFM says?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ignoring winds and other factors, it depends on &lt;strong&gt;effective runway length&lt;/strong&gt;, not just runway length. If you have a runway long (really long) enough, you can takeoff/land in either direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned &lt;a href=&quot;http://principalair.ca/article%20-%20Runway%20Slope.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... advantage or disadvantage of a sloped runway is that a 1% runway&#xA;  gradient — an increase or decrease in altitude of 10’ for every 1000’&#xA;  of runway length — is equivalent to a 10% increase or decrease in&#xA;  &lt;em&gt;effective runway length&lt;/em&gt; ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Runway length is 1500' with 3% up-slope gradient&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landing uphill on it will give us an &lt;em&gt;effective runway length&lt;/em&gt; of almost 2000’ (1500’ x 1.3 = 1950’).&lt;/li&gt;&#xA;&lt;li&gt;Landing downhill on it will give us an &lt;em&gt;effective runway length&lt;/em&gt; of just over 1000’ (1500’ x 0.7 = 1050’).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Just for reference, the runway (6: uphill; 24: downhill) at Lukla Airport has 12% gradient and is 1500' long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effective Runway Lengths (using the formula above)&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; 6: 1500' x |(1+1.2)| = 3300'&#xA;24: 1500' x |(1-1.2)| =  300'&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Hence, hypothetically speaking, if runway 24 is 48,400' long with no wind, A380 &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Specifications&quot; rel=&quot;noreferrer&quot;&gt;can&lt;/a&gt; takeoff too.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-04T16:46:44.883" LastActivityDate="2014-12-04T16:46:44.883" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9990" PostTypeId="2" ParentId="8046" CreationDate="2014-12-03T21:05:39.380" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://books.google.com/books/about/The_Killing_Zone_How_Why_Pilots_Die.html?id=GFh_by5Ao6AC&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;The Killing Zone: How &amp;amp; Why Pilots Die&lt;/em&gt;&lt;/a&gt; by Paul Craig (excellent book) has the results of an FAA study of this question, called &lt;em&gt;&lt;a href=&quot;http://books.google.com/books/about/Private_Pilot_Flight_Skill_Retention_8_1.html?id=6Y7fPAAACAAJ&quot; rel=&quot;noreferrer&quot;&gt;Private Pilot Flight Skill Retention 8, 16, and 24 Months Following Certification&lt;/a&gt;&lt;/em&gt;. This table from the study lists the 27 skills they examined and the percentage of pilots who could perform them to &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/&quot; rel=&quot;noreferrer&quot;&gt;PTS standards&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7cmsY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on this data, the first skills to go are accelerated stalls and magnetic compass turns: both were at 51% after 8 months. In some cases it seems obvious why the skill degrades: most pilots rarely - if ever - need to make magnetic compass turns so it isn't surprising that that particular skill goes away quickly. On the other hand, after 2 years only 60% of pilots could take off properly, only 51% could land properly at an uncontrolled airport and only 54% at a controlled one. That's all rather worrying considering that pilots usually take off and land at least once per flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how to assess and improve these skills, you could systematically work through this list in practice flights (like &lt;a href=&quot;http://flightchops.com/&quot; rel=&quot;noreferrer&quot;&gt;this guy&lt;/a&gt; has been doing in his last couple of videos), and/or get a regular review with an instructor. Just because the FAA requires a review once every 2 years doesn't mean that you have to wait that long: every 12 months or even every 6 may be more useful, especially for new pilots. Additional flight training of any kind will also help you to keep your skills sharp: get an instrument rating, commercial license, tailwheel endorsement, seaplane rating, glider rating, checkout in a new aircraft model etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But whatever approach you take, the first step is to critically review your own performance after every flight and make notes about what you did well and what you need to improve. If you don't do that, you have little or no chance of coming up with a good self-improvement plan.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-03T21:14:31.333" LastActivityDate="2014-12-03T21:14:31.333" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="9991" PostTypeId="2" ParentId="8046" CreationDate="2014-12-03T21:40:22.653" Score="0" Body="&lt;p&gt;its says &quot;aircraft,&quot; so I will answer for the categories and ratings I hold:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Airplane Single Engine Land/Sea -- landings&lt;/li&gt;&#xA;&lt;li&gt;Rotorcraft/helicopter -- autorotations&lt;/li&gt;&#xA;&lt;li&gt;Gliders -- tow rope breaks&lt;/li&gt;&#xA;&lt;li&gt;Tailwheel -- wheel landings&lt;/li&gt;&#xA;&lt;li&gt;Complex + high-performance -- managing cowl flaps, wing flaps, rudder trim, engine cool-down, gear, etc.&lt;/li&gt;&#xA;&lt;li&gt;High-altitude -- emergency descent to 10,000ft&lt;/li&gt;&#xA;&lt;li&gt;Instrument/airplane -- partial panel&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-03T21:40:22.653" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9992" PostTypeId="1" AcceptedAnswerId="9994" CreationDate="2014-12-03T22:17:04.890" Score="1" ViewCount="1834" Body="&lt;p&gt;My flight school's Cessna 152 is 30 years old. After refueling, the engine RPM went down and down. I tried putting full throttle in but it just stopped. Was it air in the fuel line or something more serious?&lt;/p&gt;&#xA;" OwnerUserId="4433" LastEditorUserId="64" LastEditDate="2015-01-09T22:47:57.747" LastActivityDate="2015-01-09T22:47:57.747" Title="What would cause an RPM drop and engine cutoff after starting a Cessna 152?" Tags="&lt;general-aviation&gt;&lt;piston-engine&gt;&lt;cessna-152&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-12-04T14:57:03.607" ContentLicense="CC BY-SA 3.0" />
  <row Id="9993" PostTypeId="2" ParentId="9988" CreationDate="2014-12-03T23:40:12.277" Score="2" Body="&lt;p&gt;Firstly, your intuition doesn't really apply in terms of basic thermodynamics (but, as I'll explain, you're kind of right):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Boyle's Law&lt;/strong&gt;: &quot;For a fixed mass of gas, at a constant temperature, the product (pressure x volume) is a constant.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pressure &lt;strong&gt;does&lt;/strong&gt; increase linearly [assuming the temperature stays the same]: if you squash an amount of a gas into half the volume, the pressure will double (assuming you keep the temperature the same). If you squash it into half the volume again, the pressure will double again (4x the original)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However you're also right in that we don't simply increase pressure by the same amount as we go along: Each stage compresses the air by a different amount (otherwise an engine would look like a weird triangle). and perhaps more importantly we can't maintain a constant temperature in an engine... as we compress the air into a smaller volume the temperature increases unless the air is being cooled in some way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, though, you can calculate the pressure change at each stage if you know how much the volume reduces by (ie how much smaller each chamber is than the last) and the temperature of the air in each.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-12-03T23:40:12.277" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="9994" PostTypeId="2" ParentId="9992" CreationDate="2014-12-04T01:03:20.087" Score="1" Body="&lt;p&gt;Gradual power loss would not be caused by &quot;air in the fuel lines&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most likely cause is blocked vents. There are pipes that allow air into the tanks so the fuel will flow out. If they are blocked for any reason, fuel will stop flowing, often in a gradual manner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility is that there is corrosion or sediment which is blocking the fuel line. Are you checking drain valves on every preflight and after refueling?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2014-12-04T01:03:20.087" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9995" PostTypeId="1" CreationDate="2014-12-04T09:22:40.420" Score="26" ViewCount="18333" Body="&lt;p&gt;I am a student in his last semester going for a B.S. in Computer Science. I would like to eventually transition into the space exploration industry (NASA, SpaceX, Boeing, Lockheed Martin, etc). I know nothing about avionics and i would like to learn more about the subject, specifically the software side. I have found little information online. Please give me reference material (books, websites, etc.) to learn about this area. Your point of view and additional information is strongly welcomed.&lt;/p&gt;&#xA;" OwnerUserId="4438" LastEditorUserId="938" LastEditDate="2014-12-04T15:49:36.417" LastActivityDate="2016-01-08T15:25:55.253" Title="Where do I start learning about Avionics programming?" Tags="&lt;aircraft-systems&gt;&lt;career&gt;&lt;software&gt;" AnswerCount="8" CommentCount="13" FavoriteCount="18" ClosedDate="2016-01-18T08:51:25.383" ContentLicense="CC BY-SA 3.0" />
  <row Id="9996" PostTypeId="2" ParentId="9995" CreationDate="2014-12-04T10:58:12.357" Score="17" Body="&lt;p&gt;I suspect the only answer is &quot;on the job&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Learn both C and C++ and some embedded programming and try applying for any junior positions in companies doing avionics you'll find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mobile phones can't really be considered embedded any more, but you should be able to find a course in robotics or cybernetics (industrial controllers) or an internship involving those. An internship doing consumer electronics could help too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And don't forget the aircraft manufacturers don't do avionics themselves but either buy standard modules from vendors like Garmin or Honeywell or subcontract it to many consulting companies. And those companies often do other kinds of embedded (automotive, industrial, etc.) too.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Notes: I remotely know someone who did avionics and I don't think he specifically aimed for it; he was just good C programmer and applied for a job. I myself did some automotive, again just applied for (junior; it was right after graduation) C/C++ job in a consulting company that was originally mobile and was shifted to automotive as the original project didn't really get going.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2014-12-04T16:20:56.850" LastActivityDate="2014-12-04T16:20:56.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9997" PostTypeId="2" ParentId="9995" CreationDate="2014-12-04T16:11:56.097" Score="5" Body="&lt;p&gt;Learning &lt;strong&gt;C&lt;/strong&gt; and &lt;strong&gt;C++&lt;/strong&gt; has already been suggested, and I would also add the &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ada_(programming_language)&quot;&gt;Ada&lt;/a&gt;&lt;/strong&gt; programming language to that list. A lot of avionics software is written in those three programming languages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While learning C/C++, learning how to code properly according to coding standards for aviation software may be helpful, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recommend reading:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.stroustrup.com/JSF-AV-rules.pdf&quot;&gt;Lockheed Martin JSF coding standards&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://everyspec.com/ESA/BSSC_2000-1_I1_2000_29384/&quot;&gt;ESA C and C++ coding standards&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you would like to play around with actual avionics programming, you may be interested in getting an &lt;strong&gt;open source quadrocopter&lt;/strong&gt; (such as the one from &lt;a href=&quot;http://aeroquad.com/&quot;&gt;AeroQuad&lt;/a&gt;) as a toy and experimenting with its software.&lt;/p&gt;&#xA;" OwnerUserId="4441" LastEditorUserId="65" LastEditDate="2014-12-04T16:51:09.240" LastActivityDate="2014-12-04T16:51:09.240" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="9998" PostTypeId="2" ParentId="9995" CreationDate="2014-12-04T16:23:46.253" Score="18" Body="&lt;p&gt;Ok, I was posting this as a comment but was becoming ridiculously long...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I worked for most of my professional life in fields that are somehow related. &#xA;I can see that there are three areas of study that will help you a lot here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First: programming languages. Knowing a language used in the industry is a plus.&#xA;Now I am working in the automotive/transportation industry; I am not working on safety critical material, so we just use standard C/C++. Even at that level a good knowledge of low-level programming and software (how to write a simple driver, how to interact with a device using ioctl, etc..) are very useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before that, I worked on a field related to programming languages and compilers, especially on the simulation and analysis of concurrent code. Among the others, I briefly interacted with people working for Airbus (professors that are in academia, but help to build real software).&#xA;They still see and use a lot of Ada out there, so.. knowing that is good :) I also know for a fact that Java is also used, together with special tools for verification of the code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which bring us to the second: everything related to the &lt;em&gt;verification of software&lt;/em&gt;, both from a theoretical and a practical point of view, will help you hugely in this industry. Study and practice with runtime monitors and model checkers, at least. Learn about various static analysis techniques, like abstract interpretation. Take classes about that, if you can at your school.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And third: study and practice with embedded systems and with the (more rare) real-time OSes and how they work (and how you do program them).&#xA;Get yourself an arduino or a netduino (not a raspberry PI - too high level, too many resources there!) and practice with them. Lear about uboot. &lt;/p&gt;&#xA;" OwnerUserId="3286" LastActivityDate="2014-12-04T16:23:46.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="9999" PostTypeId="2" ParentId="9995" CreationDate="2014-12-04T16:56:06.273" Score="7" Body="&lt;p&gt;I have a friend who works in Avionics software. Including space projects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He got into it by applying for a job at companies that work in that field or similar, before then he didn't have any special avionics training or experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avionics work tends to make more use of programming languages that are not mainstream. I think there's a lot of embedded C (so general C skills may be useful) but also processor-specific assembly and languages like Ada (perhaps more so for defense avionics).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are very likely to be targeting a real-time operating system (RTOS) or microcontroller. So knowledge of these may be an advantage. You might need to write device drivers and port them to new platforms (e.g. from one microprocessor to another). You might need to program microcontrollers (e.g. 8051) in assembly or C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is likely that you would encounter a much higher stringency in terms of writing and/or using unit-tests, test-harnesses, coverage tools, integration-testing and painstaking formal documentation and review of everything.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-12-04T16:56:06.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10000" PostTypeId="2" ParentId="9995" CreationDate="2014-12-04T18:07:57.930" Score="10" Body="&lt;p&gt;For avionics, the following will be essential just to get your CV considered:-&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Good skills with C&lt;/li&gt;&#xA;&lt;li&gt;Control theory, particularly state space and beyond&lt;/li&gt;&#xA;&lt;li&gt;Related to control theory, a strong foundation in maths&lt;/li&gt;&#xA;&lt;li&gt;Experience with hard-real-time processing&lt;/li&gt;&#xA;&lt;li&gt;Experience working to coding standards&lt;/li&gt;&#xA;&lt;li&gt;Familiarity with review processes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The following would also be useful:-&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Experience of Ada, and possibly C++&lt;/li&gt;&#xA;&lt;li&gt;Some knowledge of safety-related procedures (DO-178B, MISRA, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Knowledge of test-driven development&lt;/li&gt;&#xA;&lt;li&gt;Experience of common RTOSes such as VxWorks&lt;/li&gt;&#xA;&lt;li&gt;Experience of low-level programming on microcontrollers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With a BS (not BEng) in Computer Science (not electronic engineering) then you may be at a disadvantage on some of this.  You &lt;em&gt;MUST&lt;/em&gt; choose your projects to get the right experience you want to take to employers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course you're only at the very start of your working life though.  A degree is only the start, and any employer hiring graduates will know that you need training up.  A good employer will look more at generally how bright you seem to be and how well they think you can pick up new skills.  If you're playing with tech in your free time, this is probably a good thing to bring to interviews too.&lt;/p&gt;&#xA;" OwnerUserId="4442" LastActivityDate="2014-12-04T18:07:57.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10001" PostTypeId="2" ParentId="1825" CreationDate="2014-12-05T17:37:05.417" Score="7" Body="&lt;p&gt;Since you're asking if it's &lt;strong&gt;required&lt;/strong&gt; then I believe the answer is no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, just to include the information from another answer, the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html#byIa0JACK&quot;&gt;AIM 4-2-4&lt;/a&gt; only says &quot;should&quot;, not &quot;must&quot; (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;4. Air Taxi or other commercial operators not having FAA authorized call signs &lt;strong&gt;should&lt;/strong&gt; prefix their normal identification with the phonetic&#xA;  word &quot;Tango.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE- Tango Aztec Two Four Six Four Alpha.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Second, the FAA's &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;Joint Order defining ATC regulations&lt;/a&gt; says in section 2-4-20 (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air taxi and commercial operators not having FAA authorized call&#xA;  signs. State the prefix “TANGO” on initial contact, &lt;strong&gt;if used by the&#xA;  pilot&lt;/strong&gt;, followed by the registration number. The prefix may be dropped&#xA;  in subsequent communications&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's the only mention of this prefix in the entire ATC regulations, therefore it's safe to say that controllers don't need the prefix and aren't required to do anything when they hear it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the AOPA forums there are a couple of unsupported comments that the prefix was used to give commercial flights priority in the past, and that it's still used for gathering statistics on flights today (although it seems like a very unreliable mechanism for that).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-05T17:37:05.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10002" PostTypeId="1" CreationDate="2014-12-05T19:47:33.440" Score="12" ViewCount="1175" Body="&lt;p&gt;I have read that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Combustor&quot; rel=&quot;noreferrer&quot;&gt;combustor&lt;/a&gt; volume of a jet engine is decided by the maximum altitude up to which that aircraft will fly. I'm getting confused by that, because the maximum mass flow rate will occur at sea level so the combustor volume should be decided based on sea level. Can anyone explain how the volume is decided?&lt;/p&gt;&#xA;" OwnerUserId="4446" LastEditorUserId="1961" LastEditDate="2014-12-06T10:47:07.230" LastActivityDate="2014-12-06T10:47:07.230" Title="Why is the combustor volume of a jet engine decided by altitude?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10003" PostTypeId="5" CreationDate="2014-12-05T19:56:30.397" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_152&quot; rel=&quot;nofollow&quot;&gt;Cessna 152&lt;/a&gt; is a two-seat, high-wing, tricycle gear aircraft manufactured by Cessna from 1977 to 1985. It is commonly used as a training aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_152&quot; rel=&quot;nofollow&quot;&gt;Cessna 152&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-05T19:56:30.397" LastActivityDate="2014-12-05T19:56:30.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10004" PostTypeId="4" CreationDate="2014-12-05T19:56:30.397" Score="0" Body="The Cessna 152 is a two-seat light aircraft, often used for flight training" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-05T19:56:30.397" LastActivityDate="2014-12-05T19:56:30.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10005" PostTypeId="2" ParentId="9995" CreationDate="2014-12-05T20:27:13.700" Score="5" Body="&lt;p&gt;I don't work with avionics, but I have worked with remote sensing in the context&#xA;of Earth Sciences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think these materials could be of some help in addition to what others have suggested, esp. if you happen to be interested in the science aspects (sorry the answer may be somewhat off-topic if you are not).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Programming&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to C, Fortran is still used a lot for implementing various&#xA;algorithms and models. For smaller tasks and visualisation,&#xA;people often use &lt;a href=&quot;https://www.python.org/&quot;&gt;Python&lt;/a&gt; (&lt;a href=&quot;http://www.numpy.org/&quot;&gt;numpy&lt;/a&gt;, &lt;a href=&quot;http://www.scipy.org/&quot;&gt;scipy&lt;/a&gt;, &lt;a href=&quot;http://pandas.pydata.org/&quot;&gt;pandas&lt;/a&gt;, &lt;a href=&quot;http://matplotlib.org/&quot;&gt;matplotlib&lt;/a&gt;) and &lt;a href=&quot;http://www.r-project.org/&quot;&gt;R&lt;/a&gt; (R is an excellent statistical programming language, something you would use instead of Excel for serious things).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regards to C, nobody seems to mention that secure coding is really&#xA;necessary for such high-stake applications. Seacord, 2013 is a great&#xA;book for this purpose.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Chapman, Stephen J. &lt;em&gt;Fortran 95/2003 for scientists and engineers.&lt;/em&gt; McGraw-Hill, 2008.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Seacord, Robert. &lt;em&gt;Secure Coding in C and C++ (2nd Edition) (SEI Series in Software Engineering).&lt;/em&gt; Addison-Wesley Professional, 2013.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Matloff, Norman. &lt;em&gt;Art of R Programming.&lt;/em&gt; No Starch Press, 2011.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Physics&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good fundamentals in physics are certainly vital in space exploration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of measurements done in space have to do with radiation,&#xA;so I'm adding a reference to that.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/&quot;&gt;Physics I: Classical Mechanics&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/physics/8-02-electricity-and-magnetism-spring-2002/video-lectures/&quot;&gt;Physics II: Electricity and Magnetism&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/physics/8-03-physics-iii-vibrations-and-waves-fall-2004/video-lectures/&quot;&gt;Physics III: Vibrations and Waves&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;video lectures by Prof. Walter Lewin (MIT OCW)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Halliday, David, Robert Resnick, and Jearl Walker. &lt;em&gt;Fundamentals of physics extended.&lt;/em&gt; John Wiley &amp;amp; Sons, 2010.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Petty, GW. &lt;em&gt;A First Course in Atmospheric Radiation (2nd Ed.).&lt;/em&gt; Sundog Publishing, 2006.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Mathematics&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Calculus is probably the most important thing, then linear algebra.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many problems in design and physics have to do with statistics and optimization.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/mathematics/18-06-linear-algebra-spring-2010/video-lectures/&quot;&gt;Linear Algebra&lt;/a&gt; video lectures by Prof. Gilbert Strang (MIT OCW)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Wilks, DS. &lt;em&gt;Statistical Methods in the Atmospheric Sciences.&lt;/em&gt; Academic Press, 2011.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://camdavidsonpilon.github.io/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/&quot;&gt;Probabilistic Programming &amp;amp; Bayesian Methods for Hackers&lt;/a&gt; (available online)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Kruschke, J. &lt;em&gt;Doing Bayesian Data Analysis, Second Edition: A Tutorial with R, JAGS, and Stan.&lt;/em&gt; Academic Press, 2014.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Unix/Linux&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unix operating systems are used a lot in applied sciences, embedded&#xA;systems and supercomputers.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Kerrisk, M. &lt;em&gt;The Linux Programming Interface: A Linux and UNIX System Programming Handbook.&lt;/em&gt; No Starch Press, 2010.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Lucas, MW. &lt;em&gt;Absolute FreeBSD: The Complete Guide to FreeBSD.&lt;/em&gt; No Starch Press, 2007.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;many other books, e.g. ones published by O'Reilly&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some daily reading: &lt;a href=&quot;http://phys.org/space-news/&quot;&gt;phys.org/space-news/&lt;/a&gt; (-;&lt;/p&gt;&#xA;" OwnerUserId="4447" LastEditorUserId="4447" LastEditDate="2014-12-05T22:08:17.327" LastActivityDate="2014-12-05T22:08:17.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10006" PostTypeId="1" AcceptedAnswerId="10016" CreationDate="2014-12-05T20:31:03.193" Score="10" ViewCount="2004" Body="&lt;p&gt;In the US, Flight Following is a &lt;a href=&quot;http://flighttraining.aopa.org/students/crosscountry/articles/2931.html&quot;&gt;radar service provided to VFR aircraft&lt;/a&gt; on a best-effort basis. Controllers provide traffic advisories but they don't issue clearances or instructions and the pilot is responsible for maintaining separation from other aircraft, observing altitude, airspace and other flight rules etc. Flight following is only provided when the controllers' workload permits and it may be terminated at any time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an equivalent service in Europe? I've heard of something in the UK called &quot;basic service&quot; but I don't know if it's the same thing and if it's UK only or a Europe-wide service.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-10-19T18:14:49.450" Title="Is there a European equivalent of VFR Flight Following?" Tags="&lt;air-traffic-control&gt;&lt;easa-regulations&gt;&lt;visual-flight-rules&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10007" PostTypeId="1" CreationDate="2014-12-05T21:19:21.823" Score="1" ViewCount="339" Body="&lt;p&gt;What is the best place to understand the details of drones?  Preferably something open source.  Books would also be helpful.&lt;/p&gt;&#xA;" OwnerUserId="4448" LastEditorUserId="946" LastEditDate="2014-12-06T08:43:29.193" LastActivityDate="2014-12-06T08:43:29.193" Title="Open source drone technologies" Tags="&lt;aircraft-design&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="3" ClosedDate="2014-12-06T19:36:47.000" ContentLicense="CC BY-SA 3.0" />
  <row Id="10008" PostTypeId="1" AcceptedAnswerId="10013" CreationDate="2014-12-05T22:27:25.530" Score="12" ViewCount="4645" Body="&lt;p&gt;What's a typical rate of climb for a hot air balloon, assuming stable air with no updrafts? I'm thinking of the classic 'sightseeing ride' type of balloon here.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="1467" LastEditDate="2016-05-25T10:38:37.577" LastActivityDate="2016-05-25T10:38:37.577" Title="How quickly can a hot air balloon climb?" Tags="&lt;aircraft-performance&gt;&lt;balloon&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10009" PostTypeId="2" ParentId="10008" CreationDate="2014-12-05T23:26:06.023" Score="7" Body="&lt;p&gt;It very much depends on the balloon, but 2 metres/second in actual flight is pretty typical, while most are capable of something like 3-5 m/s ascent/descent if required. Ascent and descent speeds are normally about the same for a particular balloon, but this isn't a hard and fast rule&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;sport&quot; balloons being are capable of moderately less comfortable ascent/descent speeds in the range of 5 to 10 m/s&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-12-05T23:26:06.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10010" PostTypeId="2" ParentId="1825" CreationDate="2014-12-06T00:22:24.763" Score="1" Body="&lt;p&gt;The &quot;T&quot; (Tango) designation is required to be used by controllers, as per the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;Air Traffic Controller's Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Section 4. Radio and Interphone Communications&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2−4−20. AIRCRAFT IDENTIFICATION&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Use the full identification in reply&#xA;  to aircraft with similar sounding identifications. For other aircraft,&#xA;  the same identification may be used in reply that the pilot used in&#xA;  his/her initial callup except &lt;strong&gt;use the correct identification after&#xA;  communications have been established&lt;/strong&gt;. Identify aircraft as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;Air taxi and commercial operators not having FAA authorized call signs. State the prefix “TANGO” on initial contact, if used by the&#xA;  pilot, followed by the registration number. The prefix may be dropped&#xA;  in subsequent communications. EXAMPLE− “Tango Mooney Five Five Five&#xA;  Two Quebec.” “Tango November One Two Three Four.”&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;[emphasis mine]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html#byIa0JACK&quot; rel=&quot;nofollow&quot;&gt;AIM Section 2-4-2&lt;/a&gt;  is a little more difficult to parse because it uses the term &lt;strong&gt;should&lt;/strong&gt; instead of &lt;strong&gt;must&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Call signs &lt;strong&gt;should&lt;/strong&gt; never be abbreviated on an initial contact...&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;3. Civil aircraft pilots &lt;strong&gt;should&lt;/strong&gt; state the aircraft type, model or manufacturer's name, followed by the digits/letters of the registration number. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;4. Air Taxi or other commercial operators not having FAA authorized call signs &lt;strong&gt;should&lt;/strong&gt; prefix their normal identification with the phonetic word &quot;Tango.&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[emphasis mine]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since we know item 3 is not optional even though it uses the term &lt;strong&gt;should&lt;/strong&gt;, we must question whether the use of &lt;strong&gt;should&lt;/strong&gt; in item 4 is optional, and it is my belief that not using &lt;strong&gt;tango&lt;/strong&gt; on the initial call up would violate item 1.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-08T17:18:10.603" LastActivityDate="2014-12-08T17:18:10.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10011" PostTypeId="2" ParentId="10007" CreationDate="2014-12-06T00:41:51.183" Score="2" Body="&lt;p&gt;I can think of a couple of open source UAV projects:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://wiki.paparazziuav.org/wiki/Main_Page&quot; rel=&quot;nofollow&quot;&gt;Paparazzi&lt;/a&gt; is a complete system of open source hardware and software for Unmanned Aircraft Systems, including &lt;a href=&quot;http://wiki.paparazziuav.org/wiki/Autopilots&quot; rel=&quot;nofollow&quot;&gt;autopilots&lt;/a&gt; and a &lt;a href=&quot;http://wiki.paparazziuav.org/wiki/GCS&quot; rel=&quot;nofollow&quot;&gt;ground control and planning station&lt;/a&gt;. All of the hardware plans and software source code you need to make a drone from scratch are available on &lt;a href=&quot;https://github.com/paparazzi/paparazzi-hardware&quot; rel=&quot;nofollow&quot;&gt;github&lt;/a&gt;. But not everyone has the equipment to make a printed circuit board at home.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.openpilot.org/&quot; rel=&quot;nofollow&quot;&gt;Open pilot&lt;/a&gt; is an autopilot for UAVs. They also sell hardware if I remember properly, which might make it a bit easier if you're just starting. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you just want a simple introduction to flying drones, &lt;a href=&quot;http://diydrones.com/profiles/blogs/a-newbies-guide-to-uavs&quot; rel=&quot;nofollow&quot;&gt;DIY drones&lt;/a&gt; has a quick guide to the basics. &lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-12-06T00:41:51.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10012" PostTypeId="2" ParentId="9995" CreationDate="2014-12-06T01:53:03.310" Score="2" Body="&lt;p&gt;I highly suggest looking into a software analysis course and learning a proving system such as PVS.  I went back to graduate school after 14 years in various software industries, and the software analysis course I took has easily been the most eye opening.  It wouldn't have made much sense when I was in school, but after working for many years the material clicked.  It was never a subject I felt I would enjoy, and it can be a bit dry, but once you get it, you'll never look at programming quite the same way,&lt;/p&gt;&#xA;" OwnerUserId="4450" LastActivityDate="2014-12-06T01:53:03.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10013" PostTypeId="2" ParentId="10008" CreationDate="2014-12-06T08:55:15.430" Score="7" Body="&lt;p&gt;The good balloonist will try to limit the vertical speed to 2 - 3 m/s (400-600 ft/minute) to make it easier for the passengers to accommodate to the pressure change and avoid &lt;a href=&quot;http://www.nlm.nih.gov/medlineplus/ency/article/001064.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;ear barotrauma&lt;/a&gt;. This is the main factor; technically the balloon is capable of higher vertical speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much depends on the temperature profile of the atmosphere over altitude. The gas in the balloon will &lt;a href=&quot;http://en.wikipedia.org/wiki/Adiabatic_process&quot; rel=&quot;nofollow noreferrer&quot;&gt;expand adiabatically&lt;/a&gt;, and the density difference to the surrounding air will change if the surrounding air doesn't cool at the same rate. For dry air, this cooling rate is 6.5°C per 1000m. If the atmosphere has a higher cooling rate, the balloon will accelerate, if the rate is lower, climb speed will bleed off the higher the balloon climbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For that reason, you will rarely see balloons flying at the same time as gliders. Gliders need thermals, which are best in air with a high cooling rate, whereas thermals will make the job of limiting vertical speeds in a balloon much harder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blimps need to keep their hull pressurized, and here the descent rate is limited by the ability to pump air into the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8523/how-do-blimps-control-altitude/8526#8526&quot;&gt;ballonets&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2014-12-07T03:12:47.083" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10014" PostTypeId="2" ParentId="10002" CreationDate="2014-12-06T10:42:12.793" Score="8" Body="&lt;h2&gt;Short Answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is less the volume than the length which limits the maximum altitude. The cross section of the combustor is determined by the volume flow coming from the compressor and the desired flow speed in the combustor, so this dimension is given. To enable operation at lower pressure, the length of the combustor must be sufficient, so a longer combustor will have a higher volume. That is why you have read that volume determines maximum operating altitude.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Background&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The factors which make ignition easier are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;pressure&lt;/li&gt;&#xA;&lt;li&gt;temperature, and&lt;/li&gt;&#xA;&lt;li&gt;spark energy of the ignition system&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Ignition is made harder by&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;mean fuel droplet size (bigger droplets take longer to evaporate)&lt;/li&gt;&#xA;&lt;li&gt;flow speed in the combustor, and&lt;/li&gt;&#xA;&lt;li&gt;higher turbulence intensity.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For combustion to take place, first the fuel droplets injected into the air stream need to evaporate. This is made easier by higher temperature and pressure, and the lower both are, the more &lt;a href=&quot;http://web.ecs.baylor.edu/faculty/vantreuren/EGR4347/Lesson%2016%20Combustor%20Design%20Considerations.ppt&quot;&gt;residence time of the fuel-air mixture&lt;/a&gt; in the combustor is required for good combustion. Longer combustors have higher pressure losses and weigh more, so engine designers try to limit their length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With increasing altitude, the pressure in the combustor drops because the compressor will simply lift the pressure at it's inlet by a given multiple. Therefore, combustor pressure drops in sync with ambient pressure, and the required length for sufficient combustion goes up.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-12-06T10:42:12.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10015" PostTypeId="2" ParentId="8172" CreationDate="2014-12-06T15:48:12.437" Score="3" Body="&lt;p&gt;Ratchet freak's answer is entirely correct, but I would like to add to it. A plane could have a max landing weight that is equal or greater to the max take off weight. There is no technical limitation to it: the landing gear can simply be made to be sturdier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, sturdier landing gear is heavy and expensive. A plane will (usually) be lighter when it lands than when it takes off, because it burned fuel, so the additional sturdiness will seldom (if ever) be used. Therefore, manufacturers decide to make planes that have a safe take off weight that exceeds the safe landing weight.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2014-12-06T15:48:12.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10016" PostTypeId="2" ParentId="10006" CreationDate="2014-12-06T16:40:02.837" Score="11" Body="&lt;p&gt;Yes, it is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_information_service&quot; rel=&quot;noreferrer&quot;&gt;Flight Information Service (FIS)&lt;/a&gt;. FIS is defined by ICAO, and the term is used in most of the world. &amp;quot;Flight following&amp;quot; is a local term used only in certain countries.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A flight information service (FIS) is a form of air traffic service which is available to any aircraft within a flight information region (FIR), as agreed internationally by ICAO.&lt;/p&gt;&#xA;&lt;p&gt;It is defined as information pertinent to the safe and efficient conduct of flight, and includes information on other potentially conflicting traffic, possibly derived from radar, but stopping short of providing positive separation from that traffic.&lt;/p&gt;&#xA;&lt;p&gt;Flight Information also includes:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;pre&gt;&lt;code&gt;Meteorological information&#xA;Information on aerodromes&#xA;Information on possible hazards to flight&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FIS shall be provided to all aircraft which are provided with any air traffic controller (ATC) service or are otherwise known to air traffic service units. All air traffic service units will provide an FIS to any aircraft, in addition to their other tasks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-10-19T18:14:49.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10018" PostTypeId="1" AcceptedAnswerId="10020" CreationDate="2014-12-06T21:24:58.003" Score="27" ViewCount="2866" Body="&lt;p&gt;AKA 'why is the safety briefing/training inadequate'.  I tried Googling my title and got lots of sites explaining the emergency oxygen systems, procedures etc. that I already mostly knew.  The briefing: 'Pull sharply on the tube to start the flow of oxygen' is not exactly fully informative or reassuring.  The things look so fragile that it must be fairly easy to rip the tube away from the oxygen generator/supply bus pipe/whatever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How am I supposed to know how hard to pull?  Is there some sort of click/detent that can be felt as I pull on the tube that indicates 'OK, you've turned the oxygen on'?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could not a simple mechanical flag indicate oxygen on, eg 'Pull on the tube until the indicator flag turns green', or the like?&lt;/p&gt;&#xA;" OwnerUserId="3264" LastActivityDate="2015-07-14T17:59:20.997" Title="Aircraft emergency oxygen: how hard do I pull on the mask?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10020" PostTypeId="2" ParentId="10018" CreationDate="2014-12-06T21:38:32.337" Score="22" Body="&lt;p&gt;When they first fall down they'll be too high to reach your head, pulling on them will release a switch to activate the generator and release enough slack in the line to reach down to your chest comfortably (for children).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some types are suspended by a cord connected to the switch:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ylqxe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(image source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Passenger_oxygen_mask_dsc06035.jpg&quot; rel=&quot;noreferrer&quot;&gt;wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you will just need to pull until the cord disconnects from the ceiling.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2014-12-08T15:07:16.957" LastActivityDate="2014-12-08T15:07:16.957" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10022" PostTypeId="1" AcceptedAnswerId="31077" CreationDate="2014-12-07T00:05:11.133" Score="21" ViewCount="7061" Body="&lt;p&gt;Imagine a heavy bomber &amp;ndash; such as the B52, Tu160 or B1 &amp;ndash; is heading toward a hot zone carrying a large number of AMRAAM or longer ranged missiles. Why doesn't it also carry air-to-air missiles?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I got the idea from a TV documentary about the future projection of the air forces but I don't know why they're not already doing this? Wouldn't it be a strong deterrent capability? I'm aware of the fact that such aircraft were not designed to engage hostile aircraft; neither their speed nor maneuverability is enough for that. However, I feel they caould do serious damage to enemy aircraft formations from a relatively safe distance while being under protection of the fighters like F15, F22, Su XX...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, of course the enemy would be carrying similar missiles in such a scenario. Or maybe the radar of the aircraft does not have the capability to engage air to air (I don't know if such a thing is possible). But thanks to its great lifting capacity, when compared to a fighter jet, a heavy bomber may have the advantages of getting more missiles and a more powerful jammer into the action at a time. Also, especially if the aircraft was one of the low observable ones, I think it would be a game changer in any aerial conflict even when the missiles were not longer ranged than the ones the other party would be using.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically, why do heavy bombers not carry air-to-air missiles today? And as a side question, what would be the benefits and trade-offs of such an upgrade to existing heavy bombers other than what I mentioned?&lt;/p&gt;&#xA;" OwnerUserId="4033" LastEditorUserId="15311" LastEditDate="2020-04-12T15:43:52.940" LastActivityDate="2020-12-20T14:53:25.467" Title="Why do heavy bombers not carry air-to-air missiles?" Tags="&lt;military&gt;&lt;missiles&gt;&lt;bomber&gt;&lt;ordnance&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="10023" PostTypeId="1" AcceptedAnswerId="10026" CreationDate="2014-12-07T00:07:39.747" Score="3" ViewCount="539" Body="&lt;p&gt;I'd like to know the space allocated to a typical first class passenger compared to that allocated to a typical economy class passenger. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, from &lt;a href=&quot;http://www.seatguru.com/airlines/British_Airways/British_Airways_Boeing_747-400_C.php#seatMapKeyLegend&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;SeatGuru&lt;/strong&gt;&lt;/a&gt;, I can get the pitch and width of the seats on a British Airways Boeing 747 (economy is &quot;World Traveller&quot;). But can that give me the actual space allocated? Also, the first class seat is an &quot;open suite&quot; - does that mean there's space beyond pitch and width? Anyone ever done this calculation (in square feet or square meters)?&lt;/p&gt;&#xA;" OwnerUserId="4456" LastEditorUserId="19" LastEditDate="2017-03-14T10:03:33.063" LastActivityDate="2017-03-14T10:03:33.063" Title="What is the typical space allocated to first class vs. economy class passengers?" Tags="&lt;airliner&gt;&lt;passenger&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10024" PostTypeId="2" ParentId="10018" CreationDate="2014-12-07T01:51:29.710" Score="17" Body="&lt;p&gt;You can't really pull too hard.  The tube (or a separate cord) is held in place by a pin.  As you pull down, you will pull the pin out and trigger the oxygen generator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the pin comes out, there will be much more slack tube in your hand and the resistance will drop to zero.  At that point, you shouldn't need to pull any more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of thinking how hard to pull, just think that you need to pull the mask to your face.  If you do that, it'll work just fine.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2014-12-07T01:51:29.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10025" PostTypeId="1" CreationDate="2014-12-07T08:43:17.557" Score="10" ViewCount="520" Body="&lt;p&gt;I am aware that this question is on the border of travel and aviation but nobody on the travel side of the fence seems to be able to answer it. Apologies if it is regarded as off-topic for this site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question and answers on &lt;a href=&quot;https://aviation.stackexchange.com/questions/8252/are-cargo-holds-pressurised-these-days&quot;&gt;Are cargo holds pressurised these days?&lt;/a&gt; provide some good info on pressure and temperature management in airliner cargo holds but none on noise management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As part of the process of emigrating my wife and I will be taking our cats with us on an 11 hour flight. I have travelled the route regularly on both A380 and Boeing 747 services. My experience is that the passenger cabin of the A380 is significantly quieter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will the experience for the animals in the hold be similarly quieter, or is noise in the passenger cabin separately and specifically managed?&lt;/p&gt;&#xA;" OwnerUserId="4458" LastEditorUserId="19" LastEditDate="2017-05-05T09:03:56.960" LastActivityDate="2017-05-05T09:03:56.960" Title="Will an airliner with a quieter cabin have a quieter cargo hold?" Tags="&lt;airliner&gt;&lt;noise&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10026" PostTypeId="2" ParentId="10023" CreationDate="2014-12-07T09:26:57.967" Score="0" Body="&lt;p&gt;Width and pitch give you the space that is allocated to you and your seat. First Class seats are more bulky than Economy seats, so the actually usable space is a smaller fraction than in Economy. I wonder how the square meters would convey more information; generally, in Economy you are boxed in by your neighbors, while in First you can outstretch without reaching the limits of the cabin space allocated to you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aisles are wider in First, but it will be hard to make a concrete claim on &quot;your&quot; part of the aisle. Cabin crew in First will be more tolerant of eccentric behavior, so your mileage varies. Also note that in First on wide-bodied Aircraft every seat will have direct access to the aisle, so you will not need to step over the feet of your neighbor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also get more space for your baggage (luggage). On narrow-bodied aircraft two people sit in First Class where six would sit in Economy, so you get three times more space in the overhead bins. On wide-bodied aircraft this difference is even more pronounced, count on having in First the space of 5 ore more Economy seats. The bins are smaller, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the steward will take care of your coat in First, so your space requirement is reduced as compared to Economy.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-12-07T09:26:57.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10027" PostTypeId="2" ParentId="10022" CreationDate="2014-12-07T09:55:55.523" Score="9" Body="&lt;p&gt;The biggest threat to bombers are ground-to-air missiles, and onboard air-to-air missiles will offer no protection against them. Did you ever wonder why big bombers now launch winged, self-guiding bombs instead of free-fall bombs? They are called standoff weapons for exactly the possibility to be launched outside of the range of interceptors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they should be used solely as air superiority platforms, they would be a prime target, and a single loss would be a major setback. It is more prudent to distribute the burden of achieving and maintaining air superiority over more and smaller, more maneuverable platforms, because this will provide more robustness and flexibility. Just consider today's typical conflicts: An encounter with massive fleets of enemy aircraft is unlikely (they would belong to nations with a nuclear deterrent), and fighters are supposed to establish visual contact and get confirmation from a guy who can see the target with his own eyes before they are allowed to open fire. This would be highly impractical with a converted bomber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not to say that in a future conflict such air superiority platforms would be a better choice. But in the conflicts of today the smaller fighters are cleary better. Please note that an &lt;a href=&quot;http://www.lockheedmartin.com/us/products/f22/f-22-specifications.html&quot; rel=&quot;noreferrer&quot;&gt;F-22&lt;/a&gt; weighs more than a &lt;a href=&quot;http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=79&quot; rel=&quot;noreferrer&quot;&gt;WWII four-engined bomber&lt;/a&gt;, so in a way even the small platforms of today are quite huge in the historical perspective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What they do carry are counter-electronics which try to confuse the guidance system of ground-to-air missiles.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-07T11:23:11.513" LastActivityDate="2014-12-07T11:23:11.513" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10028" PostTypeId="1" AcceptedAnswerId="10039" CreationDate="2014-12-07T10:51:04.053" Score="8" ViewCount="842" Body="&lt;p&gt;When flying an open-cockpit plane (specifically a Tiger Moth):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UNnid.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UNnid.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Towpilot (Own work) [GFDL (&lt;a href=&quot;http://www.gnu.org/copyleft/fdl.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.gnu.org/copyleft/fdl.html&lt;/a&gt;) or CC-BY-SA-3.0 (&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/3.0/)]&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://creativecommons.org/licenses/by-sa/3.0/)]&lt;/a&gt;, via Wikimedia Commons&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where helmets are worn, what precautions or certifications need to be observed to mount a small video camera (such as a GoPro) thereto, if it's even possible? Obviously it would be very bad if the camera were to come undone in flight, and there might be an effect on the helmet's impact protection, so my guess would be that it's simply not allowed, but perhaps it can be done if certain conditions are met.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="1049" LastEditDate="2017-08-28T07:29:42.733" LastActivityDate="2017-08-28T07:29:42.733" Title="Can I wear a helmet camera in an open cockpit?" Tags="&lt;safety&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10029" PostTypeId="1" CreationDate="2014-12-07T10:57:27.113" Score="3" ViewCount="121" Body="&lt;p&gt;Solar Impulse proved to be capable of flying day and night without a single drop of fuel while carrying a pilot. Wouldn't it be easier to design an unmanned solar powered aircraft? Are there any? What about helicopters? Are they more difficult to make? What about automated landing at night time? I suppose there should be a lot of people interested in fuel-free aircraft, but why the only one I've heard of is Solar Impulse?&lt;/p&gt;&#xA;" OwnerDisplayName="user4459" LastActivityDate="2014-12-07T11:41:28.373" Title="Are there any unmanned variants of Solar Impulse?" Tags="&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10030" PostTypeId="2" ParentId="10029" CreationDate="2014-12-07T11:41:28.373" Score="3" Body="&lt;p&gt;The raison d'être of Solar Impulse is to carry a single human being around for a long time. Of course an unmanned version would have better performance (I doubt it would be easier to design), but what would be the purpose of such a craft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Solar Impulse is so fragile that it can only fly in unusually clement weather, so any scheduled service is out of the question. This would need a conventional backup, and if one is around anyway, why not use the conventional backup also on the few days of the year which would allow Solar Impulse to fly? It would also save the staff of meteorologists and ground support that Solar Impulse needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For high-altitude observation &lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology&quot;&gt;solar-powered drones&lt;/a&gt; have been tested (and found lacking) in the past. Helicopters have such high power demands that solar propulsion is not a viable option.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-12-07T11:41:28.373" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10031" PostTypeId="1" CreationDate="2014-12-07T13:40:31.910" Score="4" ViewCount="2193" Body="&lt;p&gt;Is there a special way to calculate the drag produced by the propeller? Can I compute it with the standard formula for parasitic drag, with the circular area of the propeller as the wetted area?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be more specific. I have a graph of the thrust vs. the incoming speed of my propeller&lt;img src=&quot;https://i.stack.imgur.com/eZvfk.png&quot; alt=&quot;Thrust vs. incoming speed of a 8&amp;quot;x4&amp;quot; propeller (blue line)&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4199" LastEditorUserId="572" LastEditDate="2015-02-25T07:32:40.127" LastActivityDate="2019-05-28T20:26:28.390" Title="Is there a special way to calculate the (parasitic) drag produced by the propeller?" Tags="&lt;aerodynamics&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10032" PostTypeId="2" ParentId="10031" CreationDate="2014-12-07T17:02:52.383" Score="2" Body="&lt;p&gt;Not quite. The propeller accelerates air, and the cross section of the accelerated air is slightly smaller than the prop disc area. However, this jet of air will sweep surrounding air with it, so there is no clear boundary. Also, the fuselage or engine nacelle will displace the slip stream / propeller wake, so you need to check what cross section is needed to accommodate both. If you now look at the wetted area in the propeller's wake, you need to calculate two effects:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Increased dynamic pressure and surface speed with fully turbulent boundary layer, causing more friction and pressure drag, and&lt;/li&gt;&#xA;&lt;li&gt;Propeller swirl, which creates additional lift / side force on the surfaces in the prop wake. Include trim drag to counteract the swirl effects.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Fist you calculate the drag without the propeller, and then with it. The difference is the contribution of the propeller wake. For simplicity, assume a constant speed over the cross section of the propeller wake and do not include the acceleration of surrounding air. For more precision, try to add the deflection of the propeller wake by the wing and consider that the acceleration of the air flowing through the propeller disc is normal to it while the airflow itself comes from a direction described by the angle of attack and the angle of sideslip. If these are not zero relative to the propeller, the propeller wake will have a different direction than the surrounding air flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If &lt;span class=&quot;math-container&quot;&gt;$\Omega$&lt;/span&gt; is the angular velocity of the propeller, &lt;span class=&quot;math-container&quot;&gt;$v_{\infty}$&lt;/span&gt; your flight speed and &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt; the speed increase due to the propeller of the diameter &lt;span class=&quot;math-container&quot;&gt;$d$&lt;/span&gt;, your swirl &lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; is &lt;span class=&quot;math-container&quot;&gt;$$\omega = \frac{2\cdot\Delta v\cdot(v_{\infty} + \frac{\Delta V}{2})}{d^2\cdot\Omega}$$&lt;/span&gt;&#xA;The speed increase in the propeller propeller wake for a given thrust &lt;span class=&quot;math-container&quot;&gt;$T$&lt;/span&gt; is &lt;span class=&quot;math-container&quot;&gt;$$\Delta v = \sqrt{v_{\infty}^2 + \frac{4\cdot T}{\pi\cdot d^2\cdot\rho}} - v_{\infty}$$&lt;/span&gt;&#xA;in air of the density &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt;. Thrust is engine shaft power times propeller efficiency, divided by flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TwivU.png&quot; alt=&quot;side view of propeller flow&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sketch shows the stream tube going through the propeller disc (light grey) and below the pressure profile in the stream tube. Air is sucked into the propeller and pushed out at the back, and the cross section of the stream tube is proportional to the inverse of the flow speed. In the propeller disc, just half of the speed increase &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt; has occurred (Froude's hypothesis).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-ai/36369#36369&quot;&gt;This answer&lt;/a&gt; by @xxavier lead me to a &lt;a href=&quot;https://engineering.purdue.edu/~andrisan/Courses/AAE490A_S2010/Buffer/AIAA-46372-872.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;very interesting paper&lt;/a&gt; in which the drag of a Luscombe 8b with and without thrust was compared. A very thoughtful way was used to arrive at zero-thrust numbers, and the result showed that the additional drag from the propeller effects was about 30% of the total zero-lift drag without thrust.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-05-28T20:26:28.390" LastActivityDate="2019-05-28T20:26:28.390" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="10033" PostTypeId="2" ParentId="2065" CreationDate="2014-12-07T17:26:14.157" Score="0" Body="&lt;p&gt;Balked landingd it is not a simple go around or missed aproach landing, in a balked landing the airplane must be able to maintain a steady gradient of climb of at least (different for each airplane)with:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) Not more than the power that is available on each engine eight seconds after initiation of movement of the power controls from minimum flight-idle position;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) The landing gear extended;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) The wing flaps in the landing position; and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(4) A climb speed equal to VREF,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;available:&lt;a href=&quot;http://www.risingup.com/fars/info/part23-77-FAR.shtml&quot; rel=&quot;nofollow&quot;&gt;http://www.risingup.com/fars/info/part23-77-FAR.shtml&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4462" LastActivityDate="2014-12-07T17:26:14.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10034" PostTypeId="1" CreationDate="2014-12-07T17:30:55.017" Score="25" ViewCount="7377" Body="&lt;p&gt;Air is around 21% Oxygen. The bulk of air is non-flammable Nitrogen. Wouldn't surrounding the jet fuel with only O2 create more efficient and clean combustion?&lt;/p&gt;&#xA;" OwnerUserId="4463" LastEditorUserId="64" LastEditDate="2015-01-09T22:47:44.303" LastActivityDate="2015-01-09T22:47:44.303" Title="If jets carried pure O2 to use for combustion, would they be more efficient?" Tags="&lt;jet-engine&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10035" PostTypeId="2" ParentId="10034" CreationDate="2014-12-07T17:57:14.270" Score="9" Body="&lt;p&gt;Then the weight of the oxidizer would weight down the aircraft. For each kilogram of pure octane (one of the components of jet fuel) you would need around 1.7 kilogram of pure O2. In other words it would double the weight of the fuel you have to bring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also bringing your own oxidizer is what happens with rockets, it does provide higher thrust and can work where no oxygen is available in the environment like in space.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-12-07T17:57:14.270" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10036" PostTypeId="2" ParentId="10034" CreationDate="2014-12-07T17:57:59.813" Score="38" Body="&lt;p&gt;Vehicles which carry their oxidizer with them are called rockets. It is a good thing that air is not pure $O_2$, because the nitrogen, being employed as a process gas,  helps to get useful work from the combustion process. By being heated and accelerated in the combustor, it does the main work of driving the turbine and turning heat into mechanical work. Engines would be even cleaner if less oxygen is around, because already at 21% $O_2$ they run at fuel-to-air ratios well below the &lt;a href=&quot;http://en.wikipedia.org/wiki/Stoichiometry&quot; rel=&quot;nofollow noreferrer&quot;&gt;stoichiometric&lt;/a&gt; optimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you consider the amount of air flowing through the core of a modern turbofan, you will see that the amount of oxygen which needs to be available will dwarf the amount of fuel, and most of it would not burn but would replace nitrogen in its role as the process gas. It could not be carried with the airplane nor isolated from surrounding air if any meaningful payload and range should remain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some background on the combustion process, please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-12-08T08:18:20.127" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="10037" PostTypeId="2" ParentId="1086" CreationDate="2014-12-07T21:50:15.707" Score="33" Body="&lt;p&gt;Reading the answers here tells me to put a few facts into the discussion:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Piston engines are the most fuel efficient aviation engines. Their drawback is a constant power output over speed, so that thrust is inverse to speed. This helps for acceleration at take-off, but limits maximum speed. A modern piston engine uses 240 g of fuel for providing 1 kW of power over one hour: 240 g/kW-h. Diesel engines use as little as 220 g/kW-h. This number is already true for the old &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_205&quot; rel=&quot;noreferrer&quot;&gt;Jumo 205&lt;/a&gt;, among the first aviation diesel engines in operation 80 years ago.&lt;/li&gt;&#xA;&lt;li&gt;Turboprop engines are next, and their power increases a little over speed due to ram pressure (which will raise the internal pressure in the engine by approx. 30% at Mach 0.8). Their power-specific consumption is &lt;a href=&quot;http://www.srs.aero/wordpress/wp-content/uploads/2009/03/srs-tsd-002-rev-1-pw120a-sfc-analysis.pdf&quot; rel=&quot;noreferrer&quot;&gt;about 300 g/kW-h&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Jet engines are less efficient than both, but are better for flying fast and high. Their thrust drops even less with speed, so the better basis for expressing consumption is thrust, not power. The typical fuel consumption of a modern jet engine (&lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;noreferrer&quot;&gt;GE-90&lt;/a&gt;) is 30 grams of fuel per Newton of thrust over one hour (30 g/N-h) when run stationary, and twice that in cruise at Mach 0.8. Modern &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F119&quot; rel=&quot;noreferrer&quot;&gt;Military&lt;/a&gt; jet &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;noreferrer&quot;&gt;engines&lt;/a&gt; achieve 80 g/N-h at take-off and have roughly constant thrust and specific consumption over speed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In all cases, thrust is created by accelerating a mass of air backwards. The general equation for propulsive efficiency $\eta$ is $$\eta = \frac{v_{\infty}}{v_{\infty}+\frac{\Delta v}{2}},$$ where $\Delta v$ is the speed increase of the mass of air due to that acceleration. This formula shows that it is better to accelerate a big mass of air only a little than a smaller mass by a lot. Propellers do this and for that reason offer the best efficiency. Turboprops use less efficient, but lighter gas turbines for creating power, but retain the efficient propeller. Civilian turbofans try to increase the mass of air by increasing their &lt;a href=&quot;http://en.wikipedia.org/wiki/Bypass_ratio&quot; rel=&quot;noreferrer&quot;&gt;bypass ratio&lt;/a&gt;, and only the military is using the least efficient types with bypass ratios below 1, because they are the best choice at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see a plot of the thrust-specific fuel consumption in cruise condition of different engine types over their bypass ratio. The inverse relation is easily visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eiaFY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eiaFY.jpg&quot; alt=&quot;Plot of thrust specific fuel consumption over bypass ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plot of the thrust specific fuel consumption in lb of fuel per lb of thrust per hour of different engines over the logarithm of their bypass ratio (picture &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/fig3BPRTrends_web.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make a comparison between piston and turbofan engines possible, let's compare fuel consumption at take-off. The formula for static thrust of a propeller is&#xA;$$T_0 = \sqrt[\Large{3}\;]{P^2\cdot\eta_{Prop}^2\cdot\pi\cdot d_P^2\cdot\rho},$$ where $P$ is the shaft power, $d_p$ the propeller diameter and $\rho$ the air density. For our example, we use a four-bladed prop of 3.4 m diameter and an engine with 1111 kW power. Its static thrust is 10.727 kN when we assume standard atmospheric conditions and a prop efficiency of 85%. The fuel flow will be 266.6 kg per hour, and relative to thrust this is 24.8 g/N-h or just 80% of that of a modern turbofan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if even the enthusiasts could guess &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot; rel=&quot;noreferrer&quot;&gt;what airplane I used&lt;/a&gt;, because I obfuscated it by using those unfamiliar metric units. I guess nobody will argue that it is not optimized for fast flight, so this comparison should also hold for the Tu-95, for which I have less data available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a propeller will force any aircraft to fly more slowly than jets. Their efficiency tanks once the propeller tips rotate at supersonic speed, so it is best to keep cruise Mach below 0.6. But commercial traffic wants to fly as fast as economically possible, and with turbofans this limit is only reached around Mach 0.85. The faster aircraft will fly more legs in the same time, carrying more people and earning more revenue. Also, by offering the faster connection, it will turn up in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sabre_(computer_system)&quot; rel=&quot;noreferrer&quot;&gt;booking systems&lt;/a&gt; on page 1 and be the favorite with business travelers, who account for almost all the profits of airlines. &lt;strong&gt;That&lt;/strong&gt; is why we do not see many turboprops in civilian traffic anymore.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-04T15:47:43.993" LastActivityDate="2018-06-04T15:47:43.993" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="10038" PostTypeId="2" ParentId="10022" CreationDate="2014-12-07T22:24:37.613" Score="4" Body="&lt;p&gt;Air-to-air missile won't do much to save your ass once the enemy has fired their missile on you. You can force them to turn around so their missile won't get mid-course update, but you still have to evade it. And they will fire first, because they can use long-range missile that you can't afford due to weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the bombers focus on countermeasures that will help them evade missiles whether fired from ground or air. And on moment of surprise and avoiding detection in the first place. B-2 by having very small radar cross-section, reduced infra-red signature and electronic countermeasures, B-1 by flying is 200 ft above ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a risk of enemy fighters being around, there will be a friendly fighter patrol around to help. Bombers don't operate as lone wolves. Each operation is carefully planned and appropriate unit is sent to counter each known opponent. And don't forget with aerial refuelling the fighters are now able to accompany the bombers almost anywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that unless the fighters have advance warning of the bombers approaching, it's unlikely they manage to intercept. They have higher maximum speed, but maintaining it requires so much fuel that they can only maintain it for couple of minutes. So before they manage to take off, which also takes couple of minutes these days, the bombers may be easily too far.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-12-07T22:24:37.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10039" PostTypeId="2" ParentId="10028" CreationDate="2014-12-08T00:35:57.547" Score="8" Body="&lt;p&gt;It's certainly &lt;em&gt;possible&lt;/em&gt; to use a GoPro in a Tiger Moth: there are &lt;a href=&quot;https://www.google.com/webhp?sourceid=chrome-instant&amp;amp;ion=1&amp;amp;espv=2&amp;amp;ie=UTF-8#q=tiger%20moth%20gopro%20camera&amp;amp;tbm=vid&quot; rel=&quot;nofollow noreferrer&quot;&gt;plenty of videos&lt;/a&gt; online to prove it. That means the question is, is it legal and if so how to do it safely?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Legally, there isn't anything relevant that I could find on the &lt;a href=&quot;http://www.caa.co.uk/&quot; rel=&quot;nofollow noreferrer&quot;&gt;UK's CAA site&lt;/a&gt; (your profile says you're in the UK), but in any case most discussions on cameras in GA aircraft have been about attaching a camera to the aircraft, not to the pilot (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/96/can-i-attach-a-camera-to-the-outside-of-my-aircraft&quot;&gt;this question&lt;/a&gt;, for example). For obvious reasons, it's difficult for any aviation authority to regulate what pilots wear or carry on their person and if there are no specific regulations that means that only the general &lt;em&gt;don't do anything stupid or dangerous&lt;/em&gt; rule would apply. I assume that the UK has something equivalent to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.13&lt;/a&gt; in the US:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an aircraft in a careless or reckless manner so&#xA;  as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Note: I'm ignoring any contractual issues here, like what your insurance company or FBO allows.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a safety point of view, the main risk of a portable camera is that it comes loose and ends up blocking a control surface externally (e.g. wedging in the rudder or elevators) or a control internally (e.g. falling to the floor and getting stuck behind a rudder pedal).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One specific concern with a helmet-mounted camera is that if it does fall off then it's very close to your face and it could obstruct your vision or even just startle you, which would probably be bad news on short final with a gusting crosswind. (Pilot distraction from operating the camera controls is another potential issue but that's true of any gadget.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately I would say it comes down to how confident you are that the camera is secure and not going to get in your way: if you are, then go for it. I don't think the attachment issues are significantly different from skiing, parachuting, driving sports cars etc. with a helmet camera, and that happens all the time. And cameras are a great tool for reviewing and improving your performance (especially if you have full audio too), which makes the 'risk' very worthwhile, in my opinion.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-12-08T15:22:50.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10040" PostTypeId="5" CreationDate="2014-12-08T00:42:07.690" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_182&quot; rel=&quot;nofollow&quot;&gt;Cessna 182 Skylane&lt;/a&gt; is a four-seat, high-wing, tricycle gear aircraft manufactured by Cessna since 1956 and known for its relatively generous carrying capacity (useful load), stability in flight and short-field performance.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_182&quot; rel=&quot;nofollow&quot;&gt;Cessna 182&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:43:40.017" LastActivityDate="2014-12-08T14:43:40.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10041" PostTypeId="4" CreationDate="2014-12-08T00:42:07.690" Score="0" Body="The Cessna 182 Skylane is a four-seat light aircraft" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:43:40.017" LastActivityDate="2014-12-08T14:43:40.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10042" PostTypeId="2" ParentId="10034" CreationDate="2014-12-08T00:49:39.117" Score="4" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Ratchet freak has already mentioned, carrying oxygen would weigh an aircraft down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Peter has mentioned, a jet engine pumps air and burns some of the oxygen, not the full 21% available. Often it burns less than half of the available oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this is that the &quot;adiabatic&quot; (that means, assuming no heat transfer) flame temperature for complete combustion of all the oxygen in air is about 2000C. Add to that the fact that the compressor can preheat the incoming air up to 500C in some cases, and you would be looking at a temperature at the exit of the combustion chamber of 2500C. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet engine that could use all the oxygen in the incoming air would be more efficient, in accordance with the principles of the Carnot cycle, but unless built of &quot;unobtanium&quot; it would melt and fall apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet engine needs a turbine to do two things. The first is to drive its own compressor. The second is to drive a load (either a propellor or fan.) The turbine+prop/fan is needed because the exit velocity of the exhaust gases would be too high to be used efficiently for generating thrust. Hence putting a turbine in the exhaust path is unavoidable&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A rocket has no turbine in the exhaust path, and as a result can run at the extremely high temperatures generated by burning oxygen. It also has extremely high exhaust exit velocities, which are hopelessly inefficient at the kind of vehicle velocities required for general aviation, but are excellent for space travel, where the more energy you can impart to each ton of propellant, the less propellant you have to carry. Also most rockets to date have been single use, unlike jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we are stuck with jet engines which are unable to use all the oxygen in the fuel, due to materials issues. One way of boosting the power of a jet engine (but not the efficiency) is to use an afterburner. This is effectively a second combustion chamber, behind the turbine, where more fuel can be burnt. This creates a huge amount more energy, but comparatively little extra thrust. Remember kinetic energy=0.5mv^2 while momentum=mv. You need to match the exhaust velocity to the vehicle velocity for efficient thrust generation, and an afterburner does not do this, as its purpose is not efficiency, just a quick and dirty power boost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some designs on the drawing board for the very large gas turbines in power stations, where the gas from the turbine, having been cooled by expansion, is sent to a second combustion chamber and then through a second turbine, to enable a higher average heat-addition temperature and improve efficiency. However the benefits are small and as far as I know it has not been tried yet. I suspect it will always be too complex for aviation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More viable than oxygen would be water injection. Water/steam is now being used for cooling of industrial gas turbines, which reduces the amount of air that must be pumped by the compressor, improving efficiency. However, you would still have to carry it.  Another option (also borrowed from industrial gas turbines) would be to put a heat exchanger in the exhaust gas flow, in order to generate steam for a steam-turbine driven propellor or fan. However, I don't expect to see these tried until all the oil in the world has nearly run out!&lt;/p&gt;&#xA;" OwnerUserId="1952" LastActivityDate="2014-12-08T00:49:39.117" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="10043" PostTypeId="1" AcceptedAnswerId="10044" CreationDate="2014-12-08T00:54:25.110" Score="10" ViewCount="9522" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Ear_clearing&quot;&gt;Valsalva Maneuver&lt;/a&gt; is where a pilot or passenger pinches their nose, closes their mouth, and then attempts to exhale through their nose. It is used to equalize or clear a buildup of pressure in the ear.  I'm always nervous when I do the maneuver, though. I'm afraid I'm going to damage my eardrums in some way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Can performing the Valsalva Maneuver do damage to the ears, or is it entirely safe?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="62" LastEditDate="2014-12-08T01:00:07.157" LastActivityDate="2014-12-08T01:00:07.157" Title="Is the Valsalva Maneuver safe?" Tags="&lt;medical&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10044" PostTypeId="2" ParentId="10043" CreationDate="2014-12-08T00:59:53.963" Score="9" Body="&lt;p&gt;Yes, it's safe. It's &lt;a href=&quot;http://www.sportdiver.com/article/news/healthy-diver-ear-clearing-101&quot;&gt;taught to scuba divers&lt;/a&gt; as a standard method for equalizing air pressure, with the general caveat that it should never take too much effort and if you feel any pain or discomfort from doing it then you should stop diving and consult a doctor. Since pressure changes in the air are much more gradual than those underwater, it shouldn't be difficult at all to equalize in an aircraft.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-08T00:59:53.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10045" PostTypeId="2" ParentId="10043" CreationDate="2014-12-08T01:00:02.497" Score="1" Body="&lt;p&gt;It is safe.  Start slow if its new to you.  I used it for years at the airlines with no issues.&lt;/p&gt;&#xA;" OwnerUserId="835" LastActivityDate="2014-12-08T01:00:02.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10046" PostTypeId="5" CreationDate="2014-12-08T01:09:16.297" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;nofollow&quot;&gt;Cessna 208 Caravan&lt;/a&gt; is a turboprop, high-wing, tricycle gear utility aircraft manufactured by Cessna since 1982 and usually used for passenger and light cargo transport.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;nofollow&quot;&gt;Cessna 208 Caravan&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T01:09:16.297" LastActivityDate="2014-12-08T01:09:16.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10047" PostTypeId="4" CreationDate="2014-12-08T01:09:16.297" Score="0" Body="The Cessna 208 Caravan is a single-engine turboprop aircraft that seats up to 14 passengers" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T01:09:16.297" LastActivityDate="2014-12-08T01:09:16.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10048" PostTypeId="1" AcceptedAnswerId="10078" CreationDate="2014-12-08T01:22:07.993" Score="3" ViewCount="727" Body="&lt;p&gt;I remember hearing or reading somewhere that the Cessna Caravan was developed because Fedex had issued an &lt;a href=&quot;http://en.wikipedia.org/wiki/Request_for_proposal&quot; rel=&quot;nofollow&quot;&gt;RFP&lt;/a&gt; for a light aircraft to carry cargo on shorter routes and to unimproved airstrips. According to whatever I heard/read, that made it unique as the only mass-produced civilian aircraft to be developed based on a customer's request, at a time when manufacturers built aircraft according to their own opinion of what was needed in the market and then tried to sell them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any truth in this?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-08T17:00:13.440" Title="Was the Cessna 208 developed to meet Fedex's requirements?" Tags="&lt;aviation-history&gt;&lt;cessna-208&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10049" PostTypeId="1" AcceptedAnswerId="10054" CreationDate="2014-12-08T01:22:17.680" Score="3" ViewCount="326" Body="&lt;p&gt;I have a R820 USB SDR and I am using ADS-B to track aircraft flying near my home.  I know I could also use ACARS to track nearby aircraft.  Are there any other aircraft signals I can monitor (doesn't necessarily have to give aircraft location, just info)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="4469" LastEditorUserId="65" LastEditDate="2014-12-08T16:43:15.817" LastActivityDate="2014-12-08T16:43:15.817" Title="How do I track and visualize aircraft from home?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10050" PostTypeId="1" CreationDate="2014-12-08T01:40:35.287" Score="0" ViewCount="168" Body="&lt;p&gt;Are there any intercept jets (that can zoom climb like 1961 April 28 113,891ft Ye-66A Mig-21 Turbojet) built for heavy lift?  I see the Stargazer and Stratolaunch as really slow heavy lift vehicles that cannot zoom climb.  I saw &lt;a href=&quot;http://www.space.com/25549-boeing-fighter-jets-satellite-launches-darpa.html&quot; rel=&quot;nofollow&quot;&gt;one article&lt;/a&gt; about using an F15E as a rocket lifter.  Is it silly to dream of a purpose-built large jet that could carry a large payload (like a Pegasus rocket) and zoom climb to a high altitude (100,000ft) before releasing its heavy rocket payload?&lt;/p&gt;&#xA;" OwnerUserId="4470" LastEditorUserId="1696" LastEditDate="2014-12-08T19:36:00.650" LastActivityDate="2014-12-08T19:36:00.650" Title="Are there any heavy lift jets (like Stargazer) with zoom climb (like Ye-66A MIG-21)?" Tags="&lt;jet&gt;&lt;payload&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10052" PostTypeId="2" ParentId="10050" CreationDate="2014-12-08T06:22:39.747" Score="3" Body="&lt;p&gt;Zoom climb of the carrier is useless. The rocket can do it alone after release with the same effect and is slightly more aerodynamic as it does not have the large wings of the carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rocket starts with certain amount of energy upon release. Part of this energy is kinetic, given by speed of the carrier, and part of this energy is potential, given by altitude. Now a zoom climb means exchanging kinetic energy from going fast for potential energy to climb higher. But the total amount of energy does not change. And since the rocket still needs to increase both it's kinetic and it's potential energy (accelerate and climb) it does not really care which form of energy it gets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the orbital vehicle needs energy corresponding to 7.9 km/s and a launch aircraft like the Stargazer can give it perhaps 0.57 km/s (of which only ~0.24 km/s will be speed, the rest is the ~12 km altitude). This is a tiny fraction of what it needs, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It helps significantly that the rocket does not have to penetrate the thick low atmosphere. At 12 km the pressure is 19% of what it is at sea level. Going higher is not going to help all that much.&lt;/li&gt;&#xA;&lt;li&gt;Due to the rocket equation (the amount of fuel needed is exponential) it can still make significant difference to payload fraction.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What we are likely to see is carriers that can give the orbital vehicle more initial energy. By going faster (like the F-15), by going higher (like the Stratolaunch) or both (using scramjets it to gain some higher hypersonic speed at altitude perhaps 30 km). But they won't do zoom climb, because that does not add any energy and adds complication.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2014-12-08T06:22:39.747" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10053" PostTypeId="1" AcceptedAnswerId="10055" CreationDate="2014-12-08T07:00:29.160" Score="18" ViewCount="4976" Body="&lt;p&gt;I stumbled upon a very unusual Russian amateur built ultralight:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;One engine, two propellers configuration&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;My first impression is that it adds another useless layer of complexity and moreover it may involve some safety issue: I particularly think of the entry into a &lt;a href=&quot;/questions/tagged/spin&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spin&amp;#39;&quot; rel=&quot;tag&quot;&gt;spin&lt;/a&gt; in case of one propeller failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the rationale behind it? The pros and cons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/R1HUY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="5517" LastEditDate="2016-12-07T21:11:01.893" LastActivityDate="2016-12-07T21:11:01.893" Title="What is the rationale behind &quot;One engine - Two propellers&quot; configuration?" Tags="&lt;aircraft-design&gt;&lt;ultralight&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10054" PostTypeId="2" ParentId="10049" CreationDate="2014-12-08T07:07:03.423" Score="5" Body="&lt;p&gt;Yes, there is other signals broadcasted by aircraft, although not by all. In the General Aviation sector, at least in Europe, an on-board device known as &lt;a href=&quot;http://en.wikipedia.org/wiki/FLARM&quot; rel=&quot;nofollow noreferrer&quot;&gt;FLARM&lt;/a&gt; is being used mostly in Gliders, Helicopters, Single-Engine Piston aircraft and touring motor gliders.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FLARM is an electronic device to selectively alert pilots to potential collisions between aircraft. It is not formally an implementation of ADS-B, as it is optimised for the specific needs of small aircraft such as gliders, not for long-range communication or ATC interaction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can &lt;a href=&quot;http://www.rtl-sdr.com/receiving-decoding-flarm-tracking-gliders-helicopters-etc-using-rtl-sdr/?PageSpeed=noscript&quot; rel=&quot;nofollow noreferrer&quot;&gt;visualize these signals using some tools&lt;/a&gt; and you can also feed the data to sites like flightradar.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related Answers to FLARM: &lt;br&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8272/what-system-is-there-in-the-uk-to-prevent-collisions-between-small-aircraft/8279#8279&quot;&gt;What system is there in the UK to prevent collisions between small aircraft?&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1883/how-does-tcas-work/1889#1889&quot;&gt;How does TCAS work?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2014-12-08T07:07:03.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10055" PostTypeId="2" ParentId="10053" CreationDate="2014-12-08T07:28:49.330" Score="22" Body="&lt;p&gt;It looks as if they rotate in opposite directions. This eliminates &lt;a href=&quot;https://aviation.stackexchange.com/questions/8560/do-aeroplanes-have-to-balance-torque-like-helicopters&quot;&gt;prop torque&lt;/a&gt;, which should improve handling, especially at low speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, you are right with your impression that it adds complexity, but at least it is not completely useless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Asymmetric prop failure is indeed an issue and will markedly reduce handling qualities, and for that reason both props are close together, so if one is left, the yawing moment should be manageable if the craft flies fast enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting a single prop in the center would present it the messy flow coming from the unfaired cockpit and engine, so placing them left and right should improve inflow conditions. They are still close enough so the tail is in the prop wake and will have improved effectiveness at slow speed and on the ground. On the other hand, the outriggers will create additional drag, and it is hard to say if this arrangement will have performance benefits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2014-12-08T11:01:23.533" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10056" PostTypeId="1" AcceptedAnswerId="10058" CreationDate="2014-12-08T09:33:56.087" Score="34" ViewCount="18354" Body="&lt;p&gt;I know that military jets have autopilot, but do the pilots actually prefer to use it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I ask this question because, unlike civilian airplanes, military jets are more likely to come in a situation where the pilot may have to take quick decision and leave the designated path for some mission (e.g. to intercept a civilian jet flying on a wrong path). In such case, the autopilot may become a problem for quick maneuvering.&lt;/p&gt;&#xA;" OwnerUserId="1395" LastEditorUserId="1696" LastEditDate="2018-04-26T14:18:52.607" LastActivityDate="2018-09-20T21:18:49.067" Title="Do fighter jet pilots ever use autopilot?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;autopilot&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10057" PostTypeId="2" ParentId="10053" CreationDate="2014-12-08T10:10:34.700" Score="12" Body="&lt;p&gt;Basically it allows the benefits of multiple propellers with a single engine. At low powers increasing the number of engines decreases power-to-mass ratio. Additionally, the builder might simply have had only one engine available or affordable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Removal of prop torque, as mentioned in the accepted answer, is a clear benefit. Probably relevant for this particular ultralight, having larger propeller area at limited height. Generally having larger propeller area for power improves efficiency and reduces noise. In the design in the image the height is especially limited. Also not having the propellers in the same line with the body probably improves air flow slightly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the limited height available in the design is the actual main reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is slightly more mechanically complex than single prop, which increases weight and chance of failure.&lt;/p&gt;&#xA;" OwnerUserId="4472" LastActivityDate="2014-12-08T10:10:34.700" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10058" PostTypeId="2" ParentId="10056" CreationDate="2014-12-08T10:23:48.663" Score="40" Body="&lt;p&gt;I'm not in the military, so you could say I'm talking out my rear end here, but based on my experience as a pilot: &lt;strong&gt;yes, military pilots use the autopilot all the time&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's my reasoning, in order of most to least convincing evidence:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Punching the autopilot off takes &lt;em&gt;about a fifth of a second&lt;/em&gt;.  The button is right there on the yoke, for crying out loud.  The time it takes to turn it off is not a good reason not to have it on.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The autopilot is a labor-saving device.  When you're in an aircraft (and &lt;em&gt;particularly&lt;/em&gt; when you're solo in one) there are times when you'd rather be paying attention to your chart or setting up the FMS or stretching or eating a candy bar instead of actually flying the plane. Also, when Air Force pilots fly long repositoning flights, the autopilot reduces fatigue between in-flight refuelings (the Navy uses carriers).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Times when you might have to leave the designated path for a mission happen a lot less than you think.  Again, not in the military, I'm just basing this on the realities of fuel and the number of military aircraft out there.  Maybe if you're flying close air support for teams on the ground or something, but remember that the military is first and foremost a logistics organization - it's a machine for moving people and things from one place to another.  Most of the time, military aircraft aren't on a hair-trigger moment's notice ready-to-engage posture, they're going from one airfield to another for training or maintenance or something.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In most aircraft, you can override the autopilot if you need to anyway.  Again, never flown a military fighter aircraft, but based on what I know about flying in general, even if you're chilling in your F-22 (with the autopilot on) if you grab the stick and yank, the airplane will move.  (&lt;em&gt;I would be interested to know whether this is true of Airbus aircraft.&lt;/em&gt; EDIT: &lt;a href=&quot;https://aviation.stackexchange.com/q/53049/167&quot;&gt;Question answered&lt;/a&gt; after 4 years!)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2018-06-29T20:31:52.937" LastActivityDate="2018-06-29T20:31:52.937" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="10059" PostTypeId="2" ParentId="10034" CreationDate="2014-12-08T10:58:47.473" Score="2" Body="&lt;p&gt;Basically, reaction engines are more energy efficient the larger the amount of propellant in relation to fuel is. With a jet engine the propellant is air which happens to already contain more oxygen than is needed to burn the fuel. In theory this might change for a very fast aircraft requiring very fast exhaust velocity, but the engine design would have to change too much for it to be relevant to the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general benefit from more efficient burning (barring some specific performance requirement) would also be better fuel efficiency. Getting better fuel efficiency at the expense of carrying additional oxygen is unlikely to be useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I actually toyed with a concept for an engine similar to your idea, but, as mentioned by others, an engine that carries its own oxidizer is basically a rocket, so my concept was really a rocket-powered-bladeless-fan with characteristics similar to jet engines not an actual jet engine. So even approaching it from the opposite direction the answer is &quot;The design would have to change too much.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;People have actually tested engines based on using conflagration or detonation instead of combustion for more efficient burning of fuel. See &lt;a href=&quot;http://en.wikipedia.org/wiki/Pulse_detonation_engine&quot; rel=&quot;nofollow&quot;&gt;Pulse Detonation Engine&lt;/a&gt; for example. These still fall in the category of &quot;The design would have to change too much.&quot; Also note that they have not replaced jet engines despite the concept having been known for decades. Wikipedia has lots of articles on rare or experimental engines. You might find something close to your idea there.&lt;/p&gt;&#xA;" OwnerUserId="4472" LastEditorUserId="4472" LastEditDate="2014-12-09T07:54:24.713" LastActivityDate="2014-12-09T07:54:24.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10060" PostTypeId="1" CreationDate="2014-12-08T13:21:02.110" Score="15" ViewCount="7129" Body="&lt;p&gt;I would like to analyze jet fuels prices in 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where can I get jet fuel prices for 2014, only in USA and Russia?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As there are different types of fuels, it would be okay to get prices for one (believe, trends are the same) or for all types.&lt;/p&gt;&#xA;" OwnerUserId="2421" LastEditorUserId="65" LastEditDate="2014-12-08T18:09:37.417" LastActivityDate="2017-09-25T09:38:49.377" Title="Where I can get historical jet fuels prices?" Tags="&lt;usa&gt;&lt;fuel&gt;&lt;cost&gt;&lt;russia&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10061" PostTypeId="2" ParentId="10053" CreationDate="2014-12-08T13:37:53.007" Score="4" Body="&lt;p&gt;While the currently accepted answer would be valid in terms of eliminating prop torque had that been the setup, a close look at the photograph shows both propellers rotating in the same direction (counterclockwise from the point of view of the viewer) - the pitch of each blade is clearly visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would suggest that in this application, the two propellers are used to give the benefit of an equivalent larger overall propeller (greater propeller area), without the additional ground clearance or vertical space requirements - a larger propeller puts through more power for the same engine RPM.&lt;/p&gt;&#xA;" OwnerUserId="2003" LastActivityDate="2014-12-08T13:37:53.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10062" PostTypeId="2" ParentId="10060" CreationDate="2014-12-08T13:38:20.400" Score="5" Body="&lt;p&gt;Although they don't have historical prices, &lt;a href=&quot;http://www.airnav.com/&quot; rel=&quot;nofollow&quot;&gt;AirNav&lt;/a&gt; has a number of ways to view Jet A fuel prices &lt;a href=&quot;http://www.airnav.com/fuel/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might write them and ask if they will release historical prices to you.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2014-12-08T16:39:33.037" LastActivityDate="2014-12-08T16:39:33.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10063" PostTypeId="2" ParentId="10060" CreationDate="2014-12-08T13:57:28.380" Score="17" Body="&lt;p&gt;U.S. Energy Information Administration &lt;a href=&quot;http://www.eia.gov/dnav/pet/pet_pri_refoth_dcu_nus_m.htm&quot; rel=&quot;noreferrer&quot;&gt;keeps tabs&lt;/a&gt; on most refined and crude prices including kerosene-type jet fuel. For those who hail from metric units' land, these are in dollars per gallon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bixDA.png&quot; alt=&quot;Price history&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="337" LastEditorUserId="337" LastEditDate="2014-12-08T23:24:13.127" LastActivityDate="2014-12-08T23:24:13.127" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10064" PostTypeId="2" ParentId="10056" CreationDate="2014-12-08T14:10:25.673" Score="13" Body="&lt;p&gt;Sure, fighter pilots use autopilot quite a bit. Using an autopilot reduces fatigue on long flights and frees the pilot to navigate, manage systems, and keep a lookout for threats. Disengaging the autopilot is as simple as hitting a button in some aircraft, or just moving the stick in others - it won't slow reaction time or prevent a pilot from responding to some event. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-12-08T14:10:25.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10065" PostTypeId="1" CreationDate="2014-12-08T14:36:08.397" Score="1" ViewCount="1106" Body="&lt;p&gt;In addition to my &lt;a href=&quot;https://aviation.stackexchange.com/q/10034/65&quot;&gt;previous question&lt;/a&gt;, I am mainly concerned with burning all the fuel.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Why isn't the combustion process using all of the Oxygen in the air?&#xA;Is it because other gases are in the way and it isn't in the right place to help the reaction? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are engineers limiting the amount of fuel into the process because they know some of the Oxygen won't be available for combustion due to its proximity(lack thereof) to the fuel?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How much fuel remains un-burnt in a modern jet engine? &#xA;I thought that an after-burner was meant to use the fuel that somehow got through the whole process without combusting? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Wouldn't using pure O2 allow for a complete fuel burn? &#xA;I do get that the added weight may not make it worthwhile since we need to weigh the value of complete burn against other non-monetary concerns(like pollution).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Finally, I assume the 2000-2500 degree C temp mentioned (&lt;a href=&quot;https://aviation.stackexchange.com/a/10042/65&quot;&gt;in this answer&lt;/a&gt;) in the last post is to actually burn Oxygen. Although I know Oxygen is not flammable, I am sure everything does burn at some point. I do not want to actually burn the Oxygen.&lt;/p&gt;&#xA;" OwnerUserId="4463" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-20T15:15:29.297" Title="Using pure O2 for jet engine combustion" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-12-08T15:32:37.710" ContentLicense="CC BY-SA 3.0" />
  <row Id="10066" PostTypeId="5" CreationDate="2014-12-08T14:37:57.300" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 172 Skyhawk&lt;/a&gt; is a four-seat, high-wing, tricycle gear aircraft manufactured by Cessna since 1955 (although not &lt;em&gt;continuously&lt;/em&gt;, with a gap from 1986 until 1996); more C172s have been built than any other aircraft. They are very commonly used in flight training.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 172&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-08-22T05:46:48.237" LastActivityDate="2019-08-22T05:46:48.237" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="10067" PostTypeId="4" CreationDate="2014-12-08T14:37:57.300" Score="0" Body="The Cessna 172 Skyhawk is a four-seat light aircraft, very commonly used in flight training" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:37:57.300" LastActivityDate="2014-12-08T14:37:57.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10068" PostTypeId="5" CreationDate="2014-12-08T14:43:12.830" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_162&quot; rel=&quot;nofollow&quot;&gt;Cessna 162 Skycatcher&lt;/a&gt; is a two-seat, high-wing, tricycle gear &lt;a href=&quot;http://en.wikipedia.org/wiki/Light-sport_aircraft&quot; rel=&quot;nofollow&quot;&gt;light sport aircraft&lt;/a&gt; (LSA) manufactured by Cessna between 2009 and 2013. It was intended mainly as a training aircraft, but is not equipped and certified for IFR flight.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_162&quot; rel=&quot;nofollow&quot;&gt;Cessna 162&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:43:12.830" LastActivityDate="2014-12-08T14:43:12.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10069" PostTypeId="4" CreationDate="2014-12-08T14:43:12.830" Score="0" Body="The Cessna 162 Skycatcher is a two-seat light sport aircraft, intended mainly for flight training" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:43:12.830" LastActivityDate="2014-12-08T14:43:12.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10070" PostTypeId="5" CreationDate="2014-12-08T14:48:36.227" Score="0" Body="&lt;p&gt;A &quot;Cessna Citation&quot; is any one of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_Citation_family&quot; rel=&quot;nofollow&quot;&gt;number of business jets&lt;/a&gt; produced by Cessna.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_Citation_family&quot; rel=&quot;nofollow&quot;&gt;Cessna Citation&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:48:36.227" LastActivityDate="2014-12-08T14:48:36.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10071" PostTypeId="4" CreationDate="2014-12-08T14:48:36.227" Score="0" Body="The Cessna Citation name is used for Cessna's range of light business jets" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T14:48:36.227" LastActivityDate="2014-12-08T14:48:36.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10072" PostTypeId="2" ParentId="481" CreationDate="2014-12-08T15:03:17.307" Score="8" Body="&lt;p&gt;This is &lt;a href=&quot;http://www.aero-news.net/AnnTicker.cfm?do=main.textpost&amp;amp;id=841d7ba2-830d-4e12-854f-0078382bed3e&quot;&gt;a letter from AOPA that was published in Aero News Network&lt;/a&gt;, based on a query made to the FAA on this very topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My interpretation of this is that there is no definitive answer, and that both the pilot and the controller have a responsibility, which may answer the question regarding why both parties were suspended in case described in the OP's post.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hello Mr. Ward,&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Your email was forwarded to us here in the Air Traffic department of&#xA;  AOPA. I contacted FAA headquarters for an official response to your&#xA;  question and received the following explanation:  Guess you could say&#xA;  it is the responsibility of both the pilot and air traffic controller:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;FAA Order 7110.65 states that ATC shall vector aircraft for separation&#xA;  and safety. This includes vectoring aircraft around TFRs as well as&#xA;  traffic. For the pilot, the applicable regulation is 14 CFR 91.103&#xA;  which pertains to preflight action and states that &quot;Each pilot in&#xA;  command shall, before beginning a flight, become familiar with all&#xA;  available information concerning that flight,&quot; which includes TFRs.&#xA;  Additional regulations are covered in 14 CFR 91.13 and whichever CFR&#xA;  promulgated the TFR (e.g. 14 CFR 91.137; 14 CFR 91.138; 14 CFR 91.139;&#xA;  14 CFR 91.141; 14 CFR 91.143; 14 CFR 91.145)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;From a legal standpoint &lt;strong&gt;TFR avoidance is a joint responsibility&lt;/strong&gt;. (This&#xA;  is in no way to be construed as a legal interpretation from FAA's&#xA;  legal staff). A pilot should not file an IFR flight through a TFR. If&#xA;  they did and that flight violated the TFR, they are subject to&#xA;  enforcement action.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;From an Air Traffic Quality Assurance standpoint, &lt;strong&gt;a controller should&#xA;  not allow an IFR or VFR flight that they are working to fly though a&#xA;  TFR.&lt;/strong&gt; If they did, they would be subject to an Operational Deviation.&#xA;  However, looking at the totality of the circumstances: It is the&#xA;  pilot-in-command's (PIC's) duty to know exactly where the airspace is,&#xA;  just as it is ATC's responsibility to know where the airspace is. &lt;strong&gt;If&#xA;  ATC gave the pilot a vector that was going to take the aircraft right&#xA;  into the TFR and the pilot did not question the controller (just as if&#xA;  s/he would if being vectored into an area of known thunderstorms) then&#xA;  it is still the final responsibility of the pilot to question the&#xA;  clearance&lt;/strong&gt;, just as it would be ATC's responsibility to question a&#xA;  pilot who wanted to fly directly through a TFR. Luckily, we are not&#xA;  aware of any instance where a controller let an IFR aircraft fly into&#xA;  a TFR. However, we are aware of many cases where pilots filed flights&#xA;  directly through TFRs and thought that ATC would vector them around,&#xA;  but instead, the pilot departed VFR expecting to pick up an IFR&#xA;  clearance in the air. While waiting for ATC to respond and issue a&#xA;  clearance the pilot flew through the TFR. In those cases, FAA&#xA;  suspended pilot certificates from 30 to 150 days.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There is no question that it is bad operating practice to file an IFR&#xA;  flight through a TFR. During flight planning, pilots should avoid&#xA;  TFRs. Arguably, to deliberately file a flight plan through a known&#xA;  TFR, in and of itself, would be a violation of 14 CFR 91.103.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Hope this helps!&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Heidi J. Williams&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Manager&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[&lt;strong&gt;emphasis mine&lt;/strong&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-08T15:08:19.513" LastActivityDate="2014-12-08T15:08:19.513" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10073" PostTypeId="2" ParentId="2065" CreationDate="2014-12-08T15:20:53.777" Score="1" Body="&lt;p&gt;A balked landing is a go around in the landing configuration: flaps and slats at the required setting, gear down, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A go around can be performed in any aircraft configuration.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-08T15:20:53.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10074" PostTypeId="2" ParentId="10065" CreationDate="2014-12-08T15:24:54.633" Score="3" Body="&lt;p&gt;The compression in the forward part of a jet engine heats the air, and combustion raises its temperature again. In order to achieve efficient operation, this heating must be restricted. &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a224584.pdf&quot; rel=&quot;nofollow&quot;&gt;If air is heated above approx. 2,000 K&lt;/a&gt;, adding more energy will result in dissociation of the gas with less further heat increase. Since thrust is produced by expanding air through heating, raising combustion temperatures above 2,000 K will result in less thrust increase for the amount of fuel consumed. The most advanced engines (&lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F119&quot; rel=&quot;nofollow&quot;&gt;F-119&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;nofollow&quot;&gt;EJ-200&lt;/a&gt;) have turbine entry temperatures of 1800 K, and civilian engines operate a few 100 K below that. The number of 2000 - 2500°C (2300 - 2800 K) you got from a previous answer is way too high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oxygen starts to dissociate already between 2,000  and 4,000 K, depending on pressure, while Nitrogen will dissociate mainly above 8,000 K. The 2,000 K figure above is a soft limit, but this temperature is also a challenge for the materials of the combustion chamber and the turbine, and techniques like &lt;a href=&quot;http://www.me.umn.edu/labs/tcht/measurements/what.html&quot; rel=&quot;nofollow&quot;&gt;film cooling&lt;/a&gt; are mandatory. As you can see, using pure oxygen would greatly increase the efficiency loss due to dissociation once technology allows to run the turbine at higher temperatures than 1800 K. It would be better for jet engines if air had a lower oxygen content.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make the best use of the fuel, much more air than would be needed for stochiometric combustion is used in a modern turbojet or turbofan core. The idea is to heat the gas just as much as technically and economically possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Too much oxygen does create problems, mainly by raising the amount of nitrous oxides a jet engine produces. However, it helps to achieve largely complete combustion, even if some of the reaction happens not in the combustor, but at later stages. Combustion is never fully complete, and the remaining unburnt constituents are proportional to an inverse exponential function over time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1956" LastEditDate="2015-12-20T15:15:29.297" LastActivityDate="2015-12-20T15:15:29.297" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10075" PostTypeId="2" ParentId="481" CreationDate="2014-12-08T15:36:21.743" Score="2" Body="&lt;p&gt;Here is a specific example that seems to indicate that pilots can be inside at least some TFRs while under ATC control:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Seattle Stadiums for both Football and Baseball (Century Link Field and Safeco Stadium) are pretty much right in the approach/departure paths for KBFIs 31R / 31L runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During gametimes, there is a Stadium TFR around the stadiums to an altitude of 3,000 AGL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But plenty of aircraft, both VFR and IFR, continue to go in and out of BFI during game times, under the supervision of BFI controllers. (The airspace is Class D, below Bravo).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've even seen aircraft maneuver within the TFR (eg. not passing directly through it in a straight line; sometimes circling).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, these pilots aren't getting busted left-and-right for violating the TFR.  As long as they're communicating with the tower, and make their intentions clear, its OK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I doubt you'll see controllers clear aircraft through most TFRs, such as VIP TFRs.&#xA;But it is entirely possible you could get cleared through some TFRs.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2014-12-08T19:42:49.213" LastActivityDate="2014-12-08T19:42:49.213" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10076" PostTypeId="2" ParentId="10022" CreationDate="2014-12-08T16:33:58.890" Score="7" Body="&lt;p&gt;Putting air-to-air missiles on a bomber would take a large investment, and would be less effective than putting them on fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the sensors and systems would have to be installed on the bomber. Although space might be less of an issue on a larger aircraft, it will still add weight. Adding search radar or something similar to locate targets would be a large task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weapons systems have to go through development and testing. Doing this with a large bomber will be expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once this system is finally in service, it will not be as effective as a fighter. Bombers do not have the speed and maneuverability that fighters do, which makes it more difficult to get in a good firing position. They may have some effectiveness against other bombers, but fighter jets would easily out-maneuver the bomber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the cold war over, there is much less threat of a large-scale air war, which would be the main application for a bomber with air-to-air weapons. Small fighters are a much better match for the current threat of smaller numbers of adversaries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have mentioned, putting so many weapons on one aircraft is a big risk. Though a bomber may be a bit harder to bring down, it's a much bigger and slower target. This means that a large portion of weapons is more likely to be lost. A large threat to aircraft is surface-to-air weapons, which fighters have a greater chance of surviving.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-26T23:55:41.040" LastActivityDate="2015-04-26T23:55:41.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10077" PostTypeId="2" ParentId="662" CreationDate="2014-12-08T16:38:13.590" Score="17" Body="&lt;p&gt;Since gliders have no engines, they are often permitted to operate under special agreements called Letters of Authorization, which permit them to operate where other aircraft may not. These agreements may permit them to fly VFR in Class A airspace to capture mountain wave lift, through TFRs, through Restricted airspace, depending on the terms of the agreement with the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, in the airspace you mention near the Capitol, &lt;a href=&quot;http://www.midatlanticsoaring.org/?page_id=733&quot;&gt;there is a TFR Waiver in force which permits gliders to operate within the Capitol TFRs&lt;/a&gt;.  This Waiver supersedes the TFR rules and the associated NOTAMs. Furthermore, it permits gliders to even thermal inside the TFR if necessary for safety of flight.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-08T18:13:37.010" LastActivityDate="2014-12-08T18:13:37.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10078" PostTypeId="2" ParentId="10048" CreationDate="2014-12-08T16:51:31.473" Score="5" Body="&lt;p&gt;Evidently, the &lt;a href=&quot;http://www.avbuyer.com/articles/detail.asp?Id=230&quot;&gt;idea for the Cessna 208&lt;/a&gt; existed &lt;a href=&quot;http://books.google.com/books?id=DF4jA_vdda4C&amp;amp;pg=PA30&amp;amp;lpg=PA30&amp;amp;ots=zzAKJTgUQS&amp;amp;sig=hWsRHxNmugVih8p-DdInnFB9N8I&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=SdeFVPPaCNHmoATdwIHIBg&amp;amp;ved=0CCQQ6AEwATgU#v=onepage&quot;&gt;before FedEx got involved&lt;/a&gt;. Cessna started with a widened and stretched 206 fuselage. It was designed to replace the aging De Havilland Canada Otters, Beavers and Beech 18 aircraft in use with bush operators.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Marketing surveys from the late seventies concluded that a modern, large capacity, rugged single engine aircraft for sale could compete successfully...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They completed the first flying prototype and were expecting orders mainly from the target market of bush operators. However, the CEO of FedEx saw it on the cover of &lt;a href=&quot;http://books.google.com/books?id=rnFWX_1Z9nEC&amp;amp;pg=PA35&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=YNiFVN3XEtXZoATu0oHQBA&amp;amp;ved=0CDEQ6AEwBQ#v=onepage&quot;&gt;Flying Magazine&lt;/a&gt; and sensed opportunity. (Whether this is true or not, FedEx was looking for a small aircraft to replace trucks on some routes, and the Caravan came along at just that time.) Cessna made some changes such as adding a cargo pod to create the Cargomaster. The big orders from FedEx helped to drive the popularity of the Caravan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So FedEx was not the reason for designing the Caravan in the first place, but it was a big part of the success of the design and did influence some aspects of it.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-08T17:00:13.440" LastActivityDate="2014-12-08T17:00:13.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10079" PostTypeId="5" CreationDate="2014-12-08T17:45:03.360" Score="0" Body="&lt;p&gt;Ground operations (or ground handling) covers all servicing of an aircraft on the ground before or after flight, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Refueling&lt;/li&gt;&#xA;&lt;li&gt;Cleaning&lt;/li&gt;&#xA;&lt;li&gt;De-icing&lt;/li&gt;&#xA;&lt;li&gt;Loading/unloading cargo and passengers&lt;/li&gt;&#xA;&lt;li&gt;Providing catering and other supplies&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Maintenance is usually not considered to be part of ground handling, neither is taxiing or repositioning the aircraft on the ground.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_ground_handling&quot; rel=&quot;nofollow&quot;&gt;Aircraft ground handling&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T17:45:03.360" LastActivityDate="2014-12-08T17:45:03.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10080" PostTypeId="4" CreationDate="2014-12-08T17:45:03.360" Score="0" Body="Servicing an aircraft on the ground before or after flight" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-08T17:45:03.360" LastActivityDate="2014-12-08T17:45:03.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10081" PostTypeId="1" AcceptedAnswerId="10082" CreationDate="2014-12-08T18:23:35.580" Score="22" ViewCount="18859" Body="&lt;p&gt;I heard once that fighter jet cabins are NOT pressurized, but the pilot's suit is, which prevents problems with decompression if the cabin gets shot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But a military fighter pilot much later told me that the cabin is, in fact, pressurized and that getting shot (the cabin) and the resulting decompression are not that much of a bother, at all.&lt;/p&gt;&#xA;" OwnerUserId="4478" LastEditorUserId="65" LastEditDate="2014-12-08T20:53:38.317" LastActivityDate="2017-01-17T00:46:54.820" Title="Are fighter jet cabins pressurized?" Tags="&lt;military&gt;&lt;cabin-pressure&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10082" PostTypeId="2" ParentId="10081" CreationDate="2014-12-08T20:52:17.373" Score="15" Body="&lt;p&gt;Cabins of fighter jets are in fact pressurized, but not same as the passenger airplanes. Cabin pressure in a passenger airplane will increase (almost in a linear fashion) as the airplane climbs. However, fighters keep ambient air pressure to a certain altitude. It maintains this pressure until a certain pressure differential is met, and then cabin altitude increases to maintain this differential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore at higher altitudes, cabin pressure in a fighter jet is low enough that supplemental oxygen is required for the pilot(s). This is supplied via &lt;a href=&quot;http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Defense_Brochures-documents/Life_Support_Systems.pdf&quot;&gt;On-Board Oxygen Generation Systems&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By not pressurizing the cabin completely reduces stress on air frame and is beneficial during an unplanned decompression.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;By the way, your friend (military fighter pilot) is correct.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-12-08T20:52:17.373" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10083" PostTypeId="2" ParentId="9981" CreationDate="2014-12-08T20:57:10.113" Score="3" Body="&lt;p&gt;Biplanes have typically higher wing areas for the same sized aircraft. I remember I biplane that I took a ride in crashed not on hour later because on short final he caught a wind gust and ended up upside down on the runway!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Everyone was okay, but you never forget the tin can hanging off a bike sound of an airplane crash.)&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2014-12-08T20:57:10.113" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10084" PostTypeId="1" AcceptedAnswerId="10086" CreationDate="2014-12-08T21:45:17.997" Score="4" ViewCount="1868" Body="&lt;p&gt;I have an FAA 3rd class and EASA 2nd class medical. On my EASA 2nd class medical it says &quot;This medical certificate complies with ICAO standards&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To obtain an FAA commercial pilot license, will I need to re-take the 2nd class medical by FAA standards with a different AME or does the FAA accept an &quot;ICAO compliant&quot; medical?&lt;/p&gt;&#xA;" OwnerUserId="577" LastEditorUserId="65" LastEditDate="2015-03-03T19:36:37.320" LastActivityDate="2015-03-03T19:36:37.320" Title="For an FAA commercial license, can I use EASA/ICAO 2nd class medical?" Tags="&lt;faa&gt;&lt;medical&gt;&lt;easa&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10086" PostTypeId="2" ParentId="10084" CreationDate="2014-12-08T22:48:59.587" Score="1" Body="&lt;p&gt;FAA medical certificate requirements &lt;a href=&quot;https://www.faa.gov/pilots/become/medical/&quot; rel=&quot;nofollow&quot;&gt;are&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Medical certificates are designated as first-class, second-class, or&#xA;  third-class.&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;First-class is designed for the airline transport pilot&lt;/li&gt;&#xA;  &lt;li&gt;Second-class for the commercial pilot&lt;/li&gt;&#xA;  &lt;li&gt;Third-class for the student, recreational and private pilot&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Coming to your question, &lt;a href=&quot;http://www.nbaa.org/admin/personnel/medical/medical-certificates.php&quot; rel=&quot;nofollow&quot;&gt;this site states&lt;/a&gt; &lt;em&gt;(my highlighting)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the ICAO naming structure for the various classes of medicals does not&#xA;  fit with that of the U.S. Under the ICAO definition, &lt;strong&gt;a second class&#xA;  medical applies only to holders of private pilot licenses&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In most States, outside of the U.S. and Canada, it is easier to simply&#xA;  carry a valid first class medical rather than trying to explain to a&#xA;  foreign inspector that &lt;strong&gt;a FAA second class medical equals an ICAO class&#xA;  1 medical&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For more information, please &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ND/8710_3E-C21.pdf&quot; rel=&quot;nofollow&quot;&gt;read this PDF&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-12-08T22:48:59.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10087" PostTypeId="1" CreationDate="2014-12-08T22:51:21.633" Score="3" ViewCount="424" Body="&lt;p&gt;I'm building a Lippisch ground effect vehicle with it's wingtips almost touching the ground, but because of torque effects the left wing actually does touch the ground, so it can't lift off. It even can't go straight.&#xA;Adding ailerons isn't an option because this problem has to be solved on te ground (zero speed) and not in the air (because it doesn't get there).&#xA;Does someone know something how I can solve this problem? &lt;/p&gt;&#xA;" OwnerUserId="4199" LastActivityDate="2014-12-09T07:24:14.520" Title="How to control torque effects on the ground?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10088" PostTypeId="2" ParentId="10087" CreationDate="2014-12-08T22:59:13.490" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_U-2&quot; rel=&quot;noreferrer&quot;&gt;The Lockheed U2&lt;/a&gt; had the same problem (bicycle wheel base and they had to prevent one end being dragged on takeoff).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They solved it by adding &quot;pogo wheels&quot; that self detach on take off. (the ones on the orange sticks.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/itMca.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source &lt;a href=&quot;http://en.wikipedia.org/wiki/File:U-_2A_Dragon_Lady_at_USAF_Museum.jpg&quot; rel=&quot;noreferrer&quot;&gt;wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-12-08T22:59:13.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10089" PostTypeId="1" AcceptedAnswerId="11134" CreationDate="2014-12-09T05:01:25.343" Score="20" ViewCount="6493" Body="&lt;p&gt;On &lt;a href=&quot;http://en.wikipedia.org/wiki/DigitalGlobe&quot; rel=&quot;noreferrer&quot;&gt;DigitalGlobe&lt;/a&gt;, I saw the following picture in an &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2866122/The-year-Stunning-series-satellite-images-world-shortlist-competition-best-aerial-shots-2014.html&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt;, which talks about some of the best aerial shots of 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pHzWG.jpg&quot; alt=&quot;Paine Field, Washington&quot;&gt;&#xA;&lt;strong&gt;&lt;em&gt;Paine Field, Washington&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1)&lt;/strong&gt; Did the plane, highlighted with a yellow circle, need to reverse to line up so neatly even though it just turned (I assume). Is the turning radius really that small that it takes very little space for a big plane to change direction so quickly on ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2)&lt;/strong&gt; Is there any special reason that all the planes are on one side of the runway and not centered on the markers? They all seem to be lined up towards the left side of the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3)&lt;/strong&gt; Isn't that too close when there is another plane parked so close in proximity? Provided there is ample space available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4)&lt;/strong&gt; Is it just that the scale of this picture, taken from a satellite, making them look closer than they really are?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;5)&lt;/strong&gt; What does that Double marking 7/91 Mean on the North East end of the small runway? usually that is a single number indicating the heading. That can't be 91, then what does that 91 mean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;6)&lt;/strong&gt; Why are  there a bunch of planes that are about stacked on top of each other towards the bottom right of the photo, on the ramp to 29?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S: I know they are parked and are not taking positions to take-off.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="39" LastEditDate="2014-12-15T03:01:49.080" LastActivityDate="2014-12-15T03:01:49.080" Title="How does Boeing park several airplanes on a single runway at Paine Field?" Tags="&lt;airport&gt;&lt;boeing&gt;&lt;taxiing&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10090" PostTypeId="2" ParentId="10089" CreationDate="2014-12-09T05:25:49.367" Score="32" Body="&lt;ol&gt;&#xA;&lt;li&gt;It was tugged to that position via tug.&lt;/li&gt;&#xA;&lt;li&gt;Angle of photo + possibly trying to offset weight, from centerline.&lt;/li&gt;&#xA;&lt;li&gt;These planes are just being stored there. They'll be tugged to another location&#xA;before they even bother to start them up, and I believe most don't&#xA;have engines on at present.&lt;/li&gt;&#xA;&lt;li&gt;They are quite close together.&lt;/li&gt;&#xA;&lt;li&gt;(from &lt;a href=&quot;https://aviation.stackexchange.com/a/10093/609&quot;&gt;@ratchetfreak's answer&lt;/a&gt;:) Turn the image around as if you are coming to land; it's actually 16L a perfectly normal runway number.&lt;/li&gt;&#xA;&lt;li&gt;Its just a very compact way of parking aircraft in minimum space. Compare the space taken up by those 4 planes versus any 4 nose-to-tail on the runway.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;These aircraft are mostly 787s that are the early teen aircraft that were rejected by the original airlines they were slated for, due to so many out of tolerance issues/rework required. They are just being stored on the runway until Boeing can get them into mod/rework status and get them to spec to be able to sell. Right now the mod line seems to be working on one of these aircraft, at a time, and each one taking many, many months to get fully reworked. &lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-12-09T14:15:30.080" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="10091" PostTypeId="2" ParentId="10084" CreationDate="2014-12-09T07:09:47.330" Score="2" Body="&lt;p&gt;You can &quot;obtain&quot; an FAA Commercial Pilot Certificate with a Third Class Medical Certificate; the Second Class Medical Certificate is only required to be able to &quot;exercise the privileges&quot; of a Commercial Pilot.&lt;/p&gt;&#xA;" OwnerUserId="4489" LastActivityDate="2014-12-09T07:09:47.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10092" PostTypeId="2" ParentId="10087" CreationDate="2014-12-09T07:24:14.520" Score="3" Body="&lt;p&gt;The commenters are right: Either use two separate propellers (left and right) which turn in opposite direction, or use a counter-rotating prop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TtxHL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture of a P-38 shows the principle. You can drive both props from the same engine by using driveshafts or belts. The Wright flyer had such an arrangement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MLW3V.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On small airplanes with very big engines a gearbox with concentric driveshafts is driving both propellers in opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3bjwO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simpler way to have contra-rotating props is to put them at opposite ends of an engine pod.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases the prop torque is reduced to zero, or in case of the podded arrangement, almost zero. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2014-12-09T07:24:14.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10093" PostTypeId="2" ParentId="10089" CreationDate="2014-12-09T09:53:03.213" Score="20" Body="&lt;ol start=&quot;5&quot;&gt;&#xA;&lt;li&gt;turn the image around as if you are coming to land; it's actually 16L a perfectly normal runway number.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-12-09T09:53:03.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10094" PostTypeId="2" ParentId="10056" CreationDate="2014-12-09T16:01:06.057" Score="5" Body="&lt;p&gt;The other answers cover almost everything, but one point that hasn't been mentioned is that the auto-pilot isn't just a labor-saving device, or even a focus-saving device: it reduces human error. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course trained pilots, especially combat veterans, can fly extremely reliably, but humans are humans, they &lt;em&gt;can&lt;/em&gt; make mistakes and simply engaging the auto-pilot between refueling points on the way to the mission zone and back will get rid of that possibility.&lt;/p&gt;&#xA;" OwnerUserId="4492" LastActivityDate="2014-12-09T16:01:06.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10095" PostTypeId="2" ParentId="1439" CreationDate="2014-12-09T16:27:43.833" Score="4" Body="&lt;p&gt;The Martin Baker MkGRU7 and EA7 on both the A6 Intruder and on the EA6B Prowler aircraft have &quot;zero-zero&quot; capability, which means that the seats could be fired at zero AGL and zero airspeed.&lt;/p&gt;&#xA;" OwnerUserId="4493" LastEditorUserId="3504" LastEditDate="2014-12-09T20:32:57.590" LastActivityDate="2014-12-09T20:32:57.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10096" PostTypeId="2" ParentId="10084" CreationDate="2014-12-09T17:38:03.647" Score="2" Body="&lt;p&gt;There's no provision in the FARs for using a foreign medical in place of an FAA one. The only place it's mentioned is under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b34f8b058693263c19199c4f73c6b736&amp;amp;node=pt14.2.61&amp;amp;rgn=div5#se14.2.61_175&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.75&lt;/a&gt;, where you can apply for an FAA foreign-based &lt;em&gt;private&lt;/em&gt; license using a foreign license and medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you don't need a second-class medical to get a commercial license, you only need it to exercise commercial privileges (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b34f8b058693263c19199c4f73c6b736&amp;amp;node=pt14.2.61&amp;amp;rgn=div5#se14.2.61_123&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.23(2)(ii)&lt;/a&gt;). If you just want to get the commercial license as a personal training/development achievement then you can use your existing third-class medical, but if you plan to use your new privileges then you do need a second-class one.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-09T17:38:03.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10097" PostTypeId="1" AcceptedAnswerId="10100" CreationDate="2014-12-09T19:26:27.590" Score="36" ViewCount="9632" Body="&lt;p&gt;It's very common to see pilots moving a light aircraft by pushing or pulling on the prop, either because there's no tow bar available or simply out of preference or convenience. Is this a reasonable thing to do or can it damage the prop or engine in some way?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="97" LastEditDate="2014-12-11T01:26:53.433" LastActivityDate="2019-10-23T22:27:37.043" Title="Is it OK to move a light aircraft by pushing or pulling the propeller?" Tags="&lt;propeller&gt;&lt;ground-operations&gt;" AnswerCount="8" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10098" PostTypeId="1" AcceptedAnswerId="10101" CreationDate="2014-12-09T19:29:25.410" Score="23" ViewCount="17421" Body="&lt;p&gt;Early propellers were made from wood and they still are on some vintage/classic aircraft and reproductions. What types of wood are typically used to make wooden propellers?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="97" LastEditDate="2014-12-11T01:22:10.010" LastActivityDate="2020-05-24T17:53:56.913" Title="What types of wood can be used for making propellers?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10099" PostTypeId="2" ParentId="10097" CreationDate="2014-12-09T19:33:01.503" Score="7" Body="&lt;p&gt;I asked around at my gliding club about this, the consensus seems to be that it won't harm the plane as long as I didn't use excessive force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for doing it is to not have to walk from wing to wing to move the plane.  The main counterpoint is that you shouldn't move a plane by yourself unless you're very sure you won't hit anything (another plane, the hangar walls, etc).&lt;/p&gt;&#xA;" OwnerUserId="2791" LastEditorUserId="609" LastEditDate="2015-04-09T14:29:27.313" LastActivityDate="2015-04-09T14:29:27.313" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10100" PostTypeId="2" ParentId="10097" CreationDate="2014-12-09T19:34:53.747" Score="37" Body="&lt;p&gt;A couple of my CFIs have asked me to help them park the airplane (in absence of a tow bar) when I was pushing the airplane by putting one hand on the hub and the other on the propeller near the hub, and them (the CFIs) pushing the tail down and nose wheel elevated. But &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/June/26/aircraft-maintenance-propeller-care&quot;&gt;according to AOPA&lt;/a&gt;, it is not a good thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... never push or pull on the prop blades. Forget what anyone has told&#xA;  you about pulling near the hub or the strength of the propeller.&#xA;  Aluminum blades can bend, and it doesn’t take much to put the blades&#xA;  out of track with one another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/News/All%20News/2005/AOPA%20Action%20(6)/sa06.pdf&quot;&gt;PDF&lt;/a&gt; says the same thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Avoid pulling the airplane around by the prop. Yes, this seems the&#xA;  perfect solution to a vexing problem of how to change the airplane’s&#xA;  position without having to walk around and get the tow bar, but it’s&#xA;  worthwhile to make the extra effort. Neither the engine nor the prop&#xA;  particularly benefit from the loads imposed by horsing the whole&#xA;  airplane around.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-05-06T14:44:38.640" LastActivityDate="2015-05-06T14:44:38.640" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10101" PostTypeId="2" ParentId="10098" CreationDate="2014-12-09T19:45:24.533" Score="26" Body="&lt;p&gt;&lt;a href=&quot;http://www.woodenpropeller.com/Basic_Propeller_Construction_-_Materials.html&quot; rel=&quot;noreferrer&quot;&gt;Historically&lt;/a&gt;, the following woods were used:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mahogany&lt;/li&gt;&#xA;&lt;li&gt;Walnut&lt;/li&gt;&#xA;&lt;li&gt;Oak&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Almost &lt;em&gt;all&lt;/em&gt; wooden propellers are reinforced to add strength. Fabric or metal coverings can be added too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ry68q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-12-09T19:45:24.533" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10102" PostTypeId="2" ParentId="10098" CreationDate="2014-12-09T19:47:09.663" Score="13" Body="&lt;p&gt;Wooden propellers can be made of &lt;a href=&quot;http://www.woodenpropeller.com/Basic_Propeller_Construction_-_Materials.html&quot;&gt;virtually any wood&lt;/a&gt;, I know &lt;a href=&quot;http://www.sensenich.com/products/browse/14/5/152/0&quot;&gt;Sensenich&lt;/a&gt; makes theirs of birch, and the company featured on &lt;a href=&quot;https://www.youtube.com/watch?v=JvLra7G31cU&quot;&gt;this episode of &quot;How It's Made&quot;&lt;/a&gt; apparently uses maple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would assume that hardwoods (birch, maple, oak, etc.) are favored over something like pine or spruce that would be easily dented in operation if the propeller kicks up rocks on the ground, though I can't find a good reference on that.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-09T19:47:09.663" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10103" PostTypeId="2" ParentId="10097" CreationDate="2014-12-09T21:13:48.120" Score="9" Body="&lt;p&gt;Well, grabbing the propeller at the blade root and pulling from there cannot hurt it. Why? Because the thrust imparted by the propeller to the aircraft is applied at exactly the same place. In other words, the propeller pulls the airplane through the air at the hub. You are so close to the hub that you're not going to create a significant bending moment along the blade. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand grabbing the propeller at the tips would be questionable at best, and ill-advised!&lt;/p&gt;&#xA;" OwnerUserId="4495" LastActivityDate="2014-12-09T21:13:48.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10104" PostTypeId="2" ParentId="10098" CreationDate="2014-12-09T21:32:18.110" Score="23" Body="&lt;p&gt;Propellers should be made from the same type of wood as wing spars: In both cases the requirements are the same, and the wood should have the highest strength to mass ratio. Both need to be light and strong, especially in tension in the case of propellers. However, using a hardwood will help with their resistance against nicks and scratches, so for the &lt;a href=&quot;http://workshopcompanion.com/KnowHow/Design/Nature_of_Wood/3_Wood_Strength/3_Wood_Strength.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;highest loadings&lt;/a&gt;, hickory, maple and oak are good candidates. Spars use softwood like pine or nordic spruce (wood from higher latitudes grows more slowly and has better strength) which are less often used for propellers. Historically a wide variety of materials has been used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=HHXlhJlPqKg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Culver Props&lt;/a&gt; selects maple for the highest strength and otherwise birch. Mahogany and cherry are selected for the looks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equally important is the glueing from &lt;a href=&quot;http://en.wikipedia.org/wiki/User:TheLongTone/Lucien_Chauviere&quot; rel=&quot;nofollow noreferrer&quot;&gt;laminated planks&lt;/a&gt; and shaping. The craftsmen at the worlds first propeller company, &lt;a href=&quot;http://www.lacanoterie.com/patrimoine/Historique%20Chauviere.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chauvière&lt;/a&gt;, were first in the business of making toilet seats. Switching to propellers came naturally. Laminating helps to control the density of the wood planks and makes it easier to cut out imperfections, so laminated propellers are better balanced and will be 25% lighter because less allowance has to be made to account for imperfections.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-05-24T17:53:56.913" LastActivityDate="2020-05-24T17:53:56.913" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="10105" PostTypeId="2" ParentId="10098" CreationDate="2014-12-10T00:12:19.340" Score="6" Body="&lt;p&gt;Birch, maple, oak, mahogany or walnut are good choices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing spar material is usually sitka spruce which is too soft for propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would not sit on a sitka toilet seat either as the slivers from it are toxic.&lt;/p&gt;&#xA;" OwnerUserId="4496" LastEditorUserId="97" LastEditDate="2014-12-11T01:25:30.880" LastActivityDate="2014-12-11T01:25:30.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10106" PostTypeId="2" ParentId="10097" CreationDate="2014-12-10T00:54:57.503" Score="22" Body="&lt;p&gt;Classic example of one corner case leading to a blanket belief.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Grabbing a propeller by the tip, especially a wooden prop, can cause damage. In use, the tips generate most of the thrust but are also held straight by the rotational forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pulling on a prop right beside the hub will cause no harm - that's where the propellor thrust goes anyway. If you grab the prop on both sides the airframe won't know that the engine isn't running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, here's a Rule of Thumb: if you cannot touch the prop hub with your thumb while pulling on the prop, you are holding it too far out.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-12-10T00:54:57.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10107" PostTypeId="1" CreationDate="2014-12-10T02:09:54.477" Score="13" ViewCount="5109" Body="&lt;p&gt;When watching landing videos of 787's that are in service I've been noticing a fan that is located under the right rear section of the fuselage.  I've now seen it on 4 different 787's  from 4 different airlines.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this an emergency fan that's deploying, or is it just something that's designed to recharge some of the batteries on board?  Some auxiliary type of system, perhaps?&lt;/p&gt;&#xA;" OwnerUserId="4498" LastEditorUserId="572" LastEditDate="2015-02-19T08:50:14.383" LastActivityDate="2016-11-17T20:02:04.343" Title="What does the small fan do that is visible on Boeing 787 Dreamliners on landing?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10108" PostTypeId="2" ParentId="751" CreationDate="2014-12-10T02:47:21.170" Score="5" Body="&lt;p&gt;I trained out of Nashville International Airport on Cessnas.  Generally, ATC was great about finding ways to fit you in to the pattern with the commercial airliners.  Occasionally, they would ask you to circle east of the airport for a little while if they were busy, but even then, they were pretty efficient about bringing the GA planes home.  (May have helped that BNA had three parallel runways, so often they could bring the smaller planes in on the center runway without disrupting the larger jets.)&lt;/p&gt;&#xA;" OwnerUserId="4500" LastActivityDate="2014-12-10T02:47:21.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10111" PostTypeId="2" ParentId="8318" CreationDate="2014-12-10T04:11:28.540" Score="4" Body="&lt;p&gt;A big part of learning to fly is learning to &quot;stay ahead of the airplane&quot;. Know what the airplane will NATURALLY do on its own, versus what you WANT it to do. Things happen a lot quicker in a jet, so a slower prop is a better place to learn this skill. One thing that pilots must learn is emergency procedures such as engine failure, and in a prop plane you have more time to make a safe decision about a forced landing.&lt;/p&gt;&#xA;" OwnerUserId="4501" LastActivityDate="2014-12-10T04:11:28.540" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10112" PostTypeId="2" ParentId="10107" CreationDate="2014-12-10T07:47:58.137" Score="17" Body="&lt;p&gt;If you are speaking of the small fan behind the gear in the photo below (click to magnify)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xYQPP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xYQPP.jpg&quot; alt=&quot;787 RAT&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;https://www.flickr.com/photos/31182650@N08/6790408327/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;you are speaking of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ram Air Turbine&lt;/a&gt;, usually used in an emergency, not in normal operations.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2014-12-11T19:28:16.477" LastActivityDate="2014-12-11T19:28:16.477" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="10113" PostTypeId="1" AcceptedAnswerId="11187" CreationDate="2014-12-10T11:34:08.903" Score="9" ViewCount="1538" Body="&lt;p&gt;I have always been struck by the complexity of cockpit controls. Aviation specialists are always on the hunt for ways to reduce cognitive overload on pilots to reduce human error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, air crash investigations have proven in a number of incidents that labelling, controls interactivity, affordances and other interface design issues impact on how pilots operate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, I have few questions: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How do human factor specialists and user experience designers differ (or not) when it comes to designing for avionics?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If user experience design skills are so different from human factor skills, wouldn't they be required when designing avionics?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If they are not so different has anyone came across a situation where user experience skills were utilised within the aviation industry?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4480" LastEditorUserId="97" LastEditDate="2015-04-22T00:44:53.910" LastActivityDate="2015-04-22T02:58:15.573" Title="Are 'human factor' specialists consulted during the UX design of cockpit controls and avionics?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;accidents&gt;&lt;avionics&gt;&lt;human-factors&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="10114" PostTypeId="2" ParentId="1389" CreationDate="2014-12-10T13:08:47.897" Score="-3" Body="&lt;p&gt;It's very simple: Prop planes are manufactured because most airports around the world have runways too short for jets.&lt;/p&gt;&#xA;" OwnerUserId="4501" LastActivityDate="2014-12-10T13:08:47.897" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10115" PostTypeId="2" ParentId="9153" CreationDate="2014-12-10T13:22:06.270" Score="5" Body="&lt;p&gt;The question for different prop rotation is very much like driving on the right side of the road (in North America), vs. on the left side (in the UK, Hong Kong, India, Japan etc.) It's all wrapped up in history and perhaps politics. BTW, Rolls-Royce turbofans turn CCW, but most GE and P&amp;amp;W fans turn CW. There's no performance advantage, one way or the other.&lt;/p&gt;&#xA;" OwnerUserId="4501" LastActivityDate="2014-12-10T13:22:06.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10116" PostTypeId="2" ParentId="2014" CreationDate="2014-12-10T15:29:51.350" Score="1" Body="&lt;p&gt;The gliders I've flown (Blanik L-23 and Grob 103) have hinged pedals with regards to controlling the rudder, and they slide closer or farther in tandem to adjust for different pilots' heights.&lt;/p&gt;&#xA;" OwnerUserId="2791" LastActivityDate="2014-12-10T15:29:51.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10117" PostTypeId="1" AcceptedAnswerId="10121" CreationDate="2014-12-10T16:51:39.653" Score="8" ViewCount="2984" Body="&lt;p&gt;My first headset used passive noise reduction (i.e. padding) and when I - very quickly - upgraded to an ANR headset, my instructor recommended keeping the passive one &quot;in case you ever fly something with an open cockpit&quot;. I can't remember if he gave me an explanation, but he definitely said that passive headsets &quot;worked better&quot; in an open cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't flown anything open so I've never had the chance to put this to the test, but is it (or was it ever) true?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-04-28T17:01:40.657" Title="Are passive or active headsets preferable in an open cockpit?" Tags="&lt;radio-communications&gt;&lt;equipment&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="10118" PostTypeId="5" CreationDate="2014-12-10T16:53:33.843" Score="0" Body="&lt;p&gt;Use this tag for any questions about aviation equipment where there is no more specific or relevant tag.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-10T16:53:33.843" LastActivityDate="2014-12-10T16:53:33.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10119" PostTypeId="4" CreationDate="2014-12-10T16:53:33.843" Score="0" Body="For questions about miscellaneous aviation equipment" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-10T16:53:33.843" LastActivityDate="2014-12-10T16:53:33.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10121" PostTypeId="2" ParentId="10117" CreationDate="2014-12-10T18:23:14.767" Score="10" Body="&lt;p&gt;First we should see how active noise reduction works. The simplest definition would be:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Active Noise Cancelling uses electric signals to reduce unwanted sounds.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The following picture on &lt;a href=&quot;http://en.wikipedia.org/wiki/Active_noise_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Active noise control&lt;/a&gt; depicts it in a simple manner:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tFBUO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tFBUO.png&quot; alt=&quot;Noise Cancelling&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then we can see what unwanted sounds ANR can actually reduce. As mentioned in &lt;a href=&quot;http://transairpilotshop.wordpress.com/2011/08/16/a-guide-to-buying-an-aviation-headset/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A Guide To Buying An Aviation Headset&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ANR headsets work best &lt;strong&gt;at frequencies below about 400-450 Hertz&lt;/strong&gt;. This&#xA;  represents the normal frequency range for speech, and also much&#xA;  propeller and exhaust noise is in this region. ANR headsets are&#xA;  therefore a significant advantage where intelligibility of&#xA;  transmissions is affected by engine and propeller noise.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In general, ANR Headsets offer greater hearing protection in&#xA;  high-noise environments but &lt;strong&gt;will do little to reduce noise at higher&#xA;  frequencies such as wind or airflow noise&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In a flying airplane (even in a slow flight), wind flow would be quite high. This &lt;a href=&quot;http://www.intricon.com/assets/documents/uploads/Info_Sheet_-_Wind_Noise_Reduction.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PDF (page 1, paragraph 3)&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The wind noise spectrum is dominated by the lower frequencies (&amp;lt; 500&#xA;  Hz), although at 27 mph when saturation is present, the wind noise&#xA;  level can be greater than 60 dB SPL at &lt;strong&gt;8 kHz&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since passive noise control is sound reduction by noise-isolating materials such as insulation, sound-absorbing tiles, or a muffler rather than a power source, in an open cockpit, passive NR headsets work better than active NR headsets.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-16T19:30:54.653" LastActivityDate="2014-12-16T19:30:54.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10122" PostTypeId="2" ParentId="2014" CreationDate="2014-12-10T18:24:11.927" Score="3" Body="&lt;p&gt;Sliding pedals are very unusual - I do not know of a single aircraft which uses them. It is also mechanically more complex and fragile - you would need to keep all those sliding lines clean, at a section of the aircraft where dirt is most common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there are three different ways to hinge the pedals. The most common one is at the bottom, but they could also be mounted on a crossbar. By using two crossbars, you get a parallelogram wich helps to keep the pedals at the same angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/P5Uwm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture shows the &quot;cockpit&quot; of the schooling glider SG-38, simply because it doesn't hide anything. As you can see, the pedals sit at the ends of the parallelogram, and you could add another hinge at their base easily for activating brakes (which the SG-38 did not have). Now you would have two degrees of freedom which make controlling two separate functions easy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The third way is to hinge the pedals from the top. This again helps to add a second degree of freedom, especially when the top hinged mechanism uses two parallel rods to again ensure a constant angle of the pedals, independent of their position relative to the hinge point.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-10T21:05:59.813" LastActivityDate="2014-12-10T21:05:59.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10123" PostTypeId="1" AcceptedAnswerId="10125" CreationDate="2014-12-10T21:52:05.843" Score="33" ViewCount="7263" Body="&lt;p&gt;Steering a seaplane on water appears to be a little more 'interesting' than steering a land aircraft, at least according to the &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/&quot; rel=&quot;noreferrer&quot;&gt;FAA Practical Test Standards&lt;/a&gt; for single-engine seaplanes (ASES), which requires the pilot to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[use] flight controls, flaps, doors, water rudder, and power correctly&#xA;  so as to follow the desired course while sailing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So how does it all work? Why/when/how do you use doors and flaps to steer? Are the water rudders connected to the pedals (like brakes on a land aircraft) or is there a separate steering control? What about braking: is there any, or do you just drift gradually to a stop?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="4095" LastEditDate="2014-12-15T09:52:15.093" LastActivityDate="2014-12-15T09:52:15.093" Title="How is a seaplane steered on water?" Tags="&lt;flight-controls&gt;&lt;taxiing&gt;&lt;seaplane&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="10124" PostTypeId="2" ParentId="10056" CreationDate="2014-12-10T22:06:30.270" Score="28" Body="&lt;p&gt;Military pilots are not unlike most other pilots: we're lazy and love booze, and we become just as autopilot crippled as the next guy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter aircraft controls are designed around the &lt;strong&gt;HOTAS&lt;/strong&gt; philosophy, or hands on throttle and stick.  To quickly perform flight critical functions, like disengaging the autopilot, the pilot's hands do not even have to move from the controls.  On the Super Hornet the preferred method to disengage the autopilot is to paddle it off with the pinky finger on the stick.  However, 5 pounds of pressure on the stick will also disengage the autopilot.  Furthermore, some autopilot functions of the super hornet are always on.  For instance, the jet constantly trims itself to 1 G and this autotrim will relatively help maintain a stable platform.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from laziness, there are times when the autopilot can be a large asset to the mission.  The cockpit of a fighter aircraft can get very busy when transitioning between phases of flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a few mission related examples off the top of my head when having some form of autopilot is really nice:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When leading another aircraft (it makes it easy for the wingman if you are stable)&lt;/li&gt;&#xA;&lt;li&gt;When flying parade and trying to do anything besides flying parade.  Flying parade sucks.&lt;/li&gt;&#xA;&lt;li&gt;Configuring mission related instruments&lt;/li&gt;&#xA;&lt;li&gt;Performing coupled approaches to the boat (scary)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are as many, if not more, reasons to use the autopilot in a fighter aircraft than in our civilian counterparts.  However, as you rightly assume, when we are flying dynamically (ie, low levels, BFM, bombing, etc), the AP is disengaged (save autotrim), and the pilot controls the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2014-12-11T00:01:21.660" LastActivityDate="2014-12-11T00:01:21.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="10125" PostTypeId="2" ParentId="10123" CreationDate="2014-12-10T22:19:56.290" Score="36" Body="&lt;p&gt;Seaplanes mostly have water rudders that are used at lower speeds and are retractable (actually, they tilt out of the water flow).  At higher speeds, like takeoff runs and landings, high speed taxis, they are retracted and the primary means of steering is the plane's rudder.  Water rudders are connected to the regular rudder pedals.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlerons can also be used to steer a seaplane on the water by creating differential lift and drag (since most ailerons don't deflect symmetrically). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doors can be used to steer by opening one or the other, creating drag on one side or the other.  I have seen a C-150 pilot do this in the air, as well.  Flaps, which create symmetrical drag, can be used to assist in slowing down but they're not useful for steering.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seaplanes have no brakes other than the drag of the floats in the water, so a seaplane pilot won't approach a dock at a perpendicular angle.  Instead, they will land along side a dock and then jump out onto a float and then to the dock, rope in hand.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seaplane pilots also carry oars, which allow them, yes, to paddle, steer, and stop the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So seaplane pilots have a number of tools at their disposal to steer the plane on the water. You can also read through the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook/media/faa-h-8083-23-3.pdf&quot;&gt;FAA Handbook for seaplane operations&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does require some coordination!&lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="1696" LastEditDate="2014-12-11T15:18:18.153" LastActivityDate="2014-12-11T15:18:18.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="10126" PostTypeId="2" ParentId="8662" CreationDate="2014-12-10T22:34:37.357" Score="1" Body="&lt;p&gt;This &quot;burping&quot; is probably happening while the engine is running too, it just can't be heard due to the engine noise. The burping noise probably emerges at the bottom of the crankcase (not in the tank) when almost all oil has been returned. This burping probably occurs because air pressure from the cylinders creates more oil flow out of the engine than the oil pump for the oil coming in, that's why there is always some oil in the tank (which is good!). That also explains why burping shouldn't be done just after stopping the engine - as we want to let the oil drip to the bottom of the crankcase to get as much oil as possible out of the engine.&lt;/p&gt;&#xA;" OwnerUserId="3559" LastActivityDate="2014-12-10T22:34:37.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="10127" PostTypeId="2" ParentId="10123" CreationDate="2014-12-11T04:58:36.323" Score="22" Body="&lt;p&gt;In addition to steering a seaplane when under power, you can 'sail' a seaplane when the engine is shut down. All you need is air movement from wind or on a river from the current taking the aircraft downstream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a good illustration:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uYqNm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;br/&gt;&lt;sup&gt;&lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/seaplanes/images/13.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think you'd want to approach a dock at a perpendicular angle doing this, but I used to often sail an old J-3 on floats to a perpendicular beaching (make sure the water rudder is up).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example let's say there is no wind, but you're on a river flowing west, and you want to reach the southern shore. The current is taking you downstream, so you have an effective west wind. When you shut down the engine, the aircraft will weathervane to face west. The rule of thumb is to use the air rudder and the ailerons to point the tail away from the bank you want to reach. Thus left rudder, left aileron down, right aileron up. You will move toward that bank of the river on the side which you have created the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a lot of fun. You can also use this technique at idle power in a strong wind for more control as well as to get yourself out of trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope I got this right, it's been 45 years since I've done it.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="65" LastEditDate="2014-12-11T15:22:08.663" LastActivityDate="2014-12-11T15:22:08.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11127" PostTypeId="2" ParentId="10097" CreationDate="2014-12-11T08:47:47.780" Score="4" Body="&lt;p&gt;By deviating from the standard procedure (using the tow bar) you incur into the following risks:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Mechanical&lt;/strong&gt; damage: you risk damaging propeller itself if you don't pull from as close as possible to the hub. Furthermore, being more complex, variable pitch blades obviously imply more risk. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arguably, the forces in play during taxiing are similar to those exerted manually through pulling. Also, in my flight school, during pre-flight inspection we actually perform some push/pulls to assess that the propeller, hub, and drive are ok -- suggesting that there is no mechanical stress derived from doing so.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Safety&lt;/strong&gt; risks: although arguably rare, you may accidentally start the engine through hand-swinging. I was instructed in my flight school to shut down the engine through the mixture control mainly to prevent this from happening during the pre-flight inspection previously described. This is also why we perform magneto ground checks during shutdown. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3042" LastEditorUserId="3504" LastEditDate="2014-12-11T14:48:07.730" LastActivityDate="2014-12-11T14:48:07.730" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11128" PostTypeId="2" ParentId="10097" CreationDate="2014-12-11T10:55:14.173" Score="-2" Body="&lt;p&gt;Regarding &quot;it must be ok to pull the plane by the prop because the prop pulls the plane through the air&quot;...&#xA;Yes....through the air. The air is much less sticky than the ground.&#xA;Also, the propeller doesn't pull the plane through the air, it pushes air behind the plane creating a lower pressure area in front of the plane and a high pressure area behind it. This &quot;pulls&quot; the plane into the low pressure area.&lt;/p&gt;&#xA;" OwnerUserId="5515" LastActivityDate="2014-12-11T10:55:14.173" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11129" PostTypeId="1" AcceptedAnswerId="11131" CreationDate="2014-12-11T14:06:18.043" Score="8" ViewCount="3159" Body="&lt;p&gt;Radio antennas and other tall buildings have lights so pilots don't fly into them, especially at night. Is there a fixed spacing so you can determine the height of the tower by counting the lights?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2014-12-11T14:27:49.017" Title="What is the spacing of obstacle lights on towers?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11130" PostTypeId="2" ParentId="11129" CreationDate="2014-12-11T14:13:12.853" Score="2" Body="&lt;p&gt;There are regulations on the color, brightness, and location of lights, but counting them doesn't tell you how high it is.  You can tell the height by looking on a sectional, which lists the heights of obstacles next to the depiction. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-11T14:13:12.853" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11131" PostTypeId="2" ParentId="11129" CreationDate="2014-12-11T14:27:49.017" Score="12" Body="&lt;p&gt;In theory you might be able to make an estimate, but practically speaking it's impossible and a lot easier to just look at a sectional chart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/b993dcdfc37fcdc486257251005c4e21/$FILE/AC70_7460_1K.pdf&quot; rel=&quot;noreferrer&quot;&gt;detailed guide&lt;/a&gt; on obstacle lighting standards, which usually applies to structures over 200ft in height but there's a lot of possible variation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Recommendations on marking and/or lighting structures can vary&#xA;  depending on terrain features, weather patterns, geographic location,&#xA;  and in the case of wind turbines, number of structures and overall&#xA;  layout of design.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The actual number of lights and their placement depends on the type and size of the structure. Appendix 1 of the FAA guide has examples for water towers, radio masts, cooling stacks, bridges, chimneys etc. The vertical light spacing seems to vary from 250-375ft, depending on the structure type, but I didn't go through it systematically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you have plenty of time you &lt;em&gt;might&lt;/em&gt; be able to determine the approximate height of a structure by comparing its lighting layout to the guide and estimating based on that, but that's very unlikely to give you an accurate number. For a pilot in flight or planning a flight, that isn't safe or practical and the simple solution is to just &lt;a href=&quot;http://skyvector.com/&quot; rel=&quot;noreferrer&quot;&gt;look at the VFR sectional chart&lt;/a&gt; to get the height. For example, this tower is 1094ft high and the top is at 1994ft above sea level (so the ground level is 900ft above sea level at that location):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zekEQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-11T14:27:49.017" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11132" PostTypeId="1" AcceptedAnswerId="11144" CreationDate="2014-12-11T16:26:01.870" Score="17" ViewCount="6213" Body="&lt;p&gt;Do you realize that we are living in a world where you can get on an airliner and disembark &lt;em&gt;cleaner than when you got on&lt;/em&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=tJijj-qMx4U&amp;amp;t=5m15s&quot;&gt;Video: Shower in A380 First Class&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This just blows my mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How much water does the Emirates A380 carry in order to provide onboard showers?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="65" LastEditDate="2014-12-11T16:59:52.973" LastActivityDate="2014-12-13T14:16:27.637" Title="How much water does the Emirates A380 carry in order to provide onboard showers?" Tags="&lt;weight-and-balance&gt;&lt;airbus-a380&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11133" PostTypeId="2" ParentId="11132" CreationDate="2014-12-11T16:45:49.637" Score="12" Body="&lt;p&gt;570 litres, &lt;a href=&quot;http://www.flightglobal.com/news/articles/water-usage-on-emirates-a380-showers-much-lower-than-318814/&quot;&gt;apparently&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To cater for the showers, the airline's 489-seat A380s are fitted with&#xA;  two optional auxiliary potable water tanks installed in the centre&#xA;  wingbox, which increases capacity from the standard 1,700 litres&#xA;  (450USgal) capacity in six tanks to 2,270 litres - ie around 2.3t.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's assuming that the 570 litre increase is entirely allocated to the showers, which may not be literally true.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-11T16:45:49.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11134" PostTypeId="2" ParentId="10089" CreationDate="2014-12-11T17:41:29.640" Score="18" Body="&lt;p&gt;Most of your questions seem to be answered by the current answers/comments, but since you are wanting more detail...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1) Did the plane, highlighted with a yellow circle, need to reverse to line up so neatly even though it just turned (I assume). Is the turning radius really that small that it takes very little space for a big plane to change direction so quickly on ground?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, either the plane in the yellow circle or the one directly behind it had to be reversed into its spot. When airplanes are being repositioned around an airport, they are typically towed, because it requires less fuel and it's easier to start up a tug and hook it up than to power up a large jet for taxi. The tug is also able to push the jet backwards when needed (which also happens routinely when the jet departs from an airport gate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airnav.com/airport/KPAE#rwys&quot; rel=&quot;noreferrer&quot;&gt;Runway 11/29&lt;/a&gt; at &lt;a href=&quot;http://www.airnav.com/airport/KPAE&quot; rel=&quot;noreferrer&quot;&gt;KPAE&lt;/a&gt; (currently closed except for taxiing for obvious reasons) has a width of &lt;strong&gt;75ft (23m)&lt;/strong&gt;. &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/787.pdf&quot; rel=&quot;noreferrer&quot;&gt;According to Boeing&lt;/a&gt;, a 787-8 (the indicated plane and all but the green 747 at the northwest end) needs &lt;strong&gt;128ft (38.9m)&lt;/strong&gt; width to make a turn. This assumes a steering angle of 70 degrees, with the R2 outer gear at one edge at the beginning of the turn at a radius of 46ft and R3 nose gear at the opposite edge halfway through turn at a radius of 82ft. So it would not be possible for a 787 to turn around on that runway. Certainly not a 747. Even if they tried to do something like a three point turn, the distance between the nose and main gear is 74ft 9in center to center, which puts the wheel distance just over the runway width.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;2) Is there any special reason that all the planes are on one side of the runway and not centered on the markers? They all seem to be lined up towards the left side of the picture.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are probably on the south side to provide as much clearance as possible for taxiway D immediately to the north (as Lnafziger commented). The taxiway to the south is &lt;a href=&quot;http://aeronav.faa.gov/content/aeronav/online/pdf_files/legendAD.pdf&quot; rel=&quot;noreferrer&quot;&gt;marked as closed&lt;/a&gt; (might be W?). The &lt;a href=&quot;http://www.airnav.com/airport/KPAE#notes&quot; rel=&quot;noreferrer&quot;&gt;Additional Remarks on AirNav&lt;/a&gt; include (&lt;em&gt;with my comments&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;...TAXIWAY D BETWEEN D2 AND ALPHA (&lt;em&gt;north section of D&lt;/em&gt;) RESTRICTED TO WINGSPAN OF 118' OR LESS. TAXIWAY D BETWEEN D2 AND GOLF (&lt;em&gt;south section of D&lt;/em&gt;) RESTRICTED TO WINGSPAN OF 49' OR LESS.&lt;/li&gt;&#xA;  &lt;li&gt;TAXIWAY W CLOSED INDEFINITELY (&lt;em&gt;probably south of runway 11/29&lt;/em&gt;).&lt;/li&gt;&#xA;  &lt;li&gt;TAXIWAY INTERSECTIONS D2, D3, AND D4 CLOSED INDEFINITELY (&lt;em&gt;between runway 11/29 and taxiway D to the north&lt;/em&gt;).&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For reference, the 787-8 has a wingspan of 197ft 3in (60.12m).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;3) Isn't that too close when there is another plane parked so close in proximity? Provided there is ample space available.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While crew must certainly take care to avoid collisions, planes can be parked very closely together if needed. See your question 6 for an example (also &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_boneyard&quot; rel=&quot;noreferrer&quot;&gt;boneyards&lt;/a&gt; or &lt;a href=&quot;http://jalopnik.com/5660984/peeping-into-the-hangar-bay-of-a-us-navy-aircraft-supercarrier&quot; rel=&quot;noreferrer&quot;&gt;aircraft carrier hangars&lt;/a&gt;). Since the planes will also be towed out of their positions, jet blast should not be a concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although there is more space at KPAE than on an aircraft carrier and fewer planes than at a boneyard, there were still issues of space with so many planes on the ground. There were issues with production and engine availability as slookabill &lt;a href=&quot;https://aviation.stackexchange.com/a/10090/1696&quot;&gt;mentioned&lt;/a&gt;, as well as the grounding due to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems&quot; rel=&quot;noreferrer&quot;&gt;battery issues&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;4) Is it just that the scale of this picture, taken from a satellite, making them look closer than they really are?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture seems to be taken from close to directly overhead, so the apparent distance is probably fairly representative. Here's &lt;a href=&quot;https://www.youtube.com/watch?v=6CXhrKu_9hY&quot; rel=&quot;noreferrer&quot;&gt;another view&lt;/a&gt; for comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;5) What does that Double marking 7/91 Mean on the North East end of the small runway? usually that is a single number indicating the heading. That can't be 91, then what does that 91 mean?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As ratchetfreak &lt;a href=&quot;https://aviation.stackexchange.com/a/10093/1696&quot;&gt;mentioned&lt;/a&gt;, the marking is at the north end of the runway, so it is meant to be viewed facing south as 16L.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;6) Why are there a bunch of planes that are about stacked on top of each other towards the bottom right of the photo, on the ramp to 29?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar to the reasons explained for the other questions, the planes are parked for some period of time. The ground crews want the planes to take up as little area as possible. These appear to be 737's and are probably parked either for maintenance or for reasons similar to the 787 (production).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2014-12-14T22:10:25.340" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11136" PostTypeId="2" ParentId="10113" CreationDate="2014-12-11T18:16:30.610" Score="2" Body="&lt;p&gt;1- My understanding is that the terms are related, but have different appliations. User experience is more about how the interface is perceived, and whether the users find it easy to learn/use. This has come into focus as computers become more and more a part of our daily lives. Human factors for aviation focuses more on the fact that there is a direct relationship between the user experience of the pilots and safety of flight. Human factors also looks into how easy it is to make mistakes, and how easy it is to see and process the required information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2- Knowledge of user experience certainly would be useful in avionics, since the end goal is to provide control and information to the crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3- I'm not sure how closely it relates to user experience, but while &lt;a href=&quot;http://history.nasa.gov/SP-4216.pdf&quot; rel=&quot;nofollow&quot;&gt;NASA was running tests with their 737&lt;/a&gt;, they tested various ideas for the avionics. Chapter 3 discusses different methods of controlling the airplane as well as HUD and electronic display technology. Chapter 7 discusses the use of a touch interface for a datalink to ATC. It is interesting to note that even when some technologies were rated very highly by the crews in the program, various obstacles kept some of them from being applied further.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-12-11T18:16:30.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11137" PostTypeId="2" ParentId="9039" CreationDate="2014-12-11T19:09:15.080" Score="7" Body="&lt;p&gt;I have checked the 01 July 1965 FAA register, and it does not show there. My father had a BT-13A N61907, and it doesn't show either. The usual fate of postwar BT's was sale to crop duster companies; they were of value only for their R-985 engines and 2D30 props to be fitted on Stearman dusters or airshow planes. The airframes were scrapped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can convince someone at FAA OKC, they could call up their archives (in Ft. Worth IIRC) and get the answer you seek.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-11T19:09:15.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11138" PostTypeId="1" AcceptedAnswerId="11140" CreationDate="2014-12-11T19:09:53.737" Score="17" ViewCount="1667" Body="&lt;p&gt;I saw this plane on a remote ramp at BKK today.  What is the purpose of aluminium foil on the wheels?  Does it mean the plane is in mothball?  I don't see other planes, even in maintenance, with aluminium foil on the tires.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6GojY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;In respect of the photo's license, I am the owner of the picture and authorize anyone to use my photo for any purpose except illegal activity.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="97" LastEditDate="2015-04-01T05:50:47.100" LastActivityDate="2015-04-01T05:50:47.100" Title="What is the purpose of aluminium foil on the wheels?" Tags="&lt;landing-gear&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11139" PostTypeId="2" ParentId="9860" CreationDate="2014-12-11T19:16:14.177" Score="-2" Body="&lt;p&gt;Has anyone mentioned the large ground crews required in launching and docking an aircraft? When labor was plentiful and cheap, this wasn't a problem. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the Hindenburg fire caused many casualties, most of them among the ground crew.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-11T19:16:14.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11140" PostTypeId="2" ParentId="11138" CreationDate="2014-12-11T19:22:51.350" Score="22" Body="&lt;p&gt;They are &lt;a href=&quot;http://www.protectivepackaging.net/aircraft-wheel-covers&quot;&gt;reflective covers&lt;/a&gt; to protect the tires from the elements, especially UV. Similar to the shades visible in the windscreen. &lt;a href=&quot;http://www.goodyearaviation.com/resources/pdf/aircraftmanual.pdf&quot;&gt;Goodyear says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft tires, like other rubber products, are affected to some degree by sunlight and extremes of weather.&#xA;  While weather-checking does not impair performance, it can be reduced by protective covers. These covers&#xA;  (ideally with light color or aluminized surface to reflect sunlight) should be placed over tires when an&#xA;  aircraft is tied down outside.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also protects the tires from other substances like oil and hydraulic fluid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane is not necessarily mothballed. I would expect it to be parked much more out of the way in that case. But the wheel and window covers do suggest that they expect it to be parked there for some time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Information is a bit sparse, but it appears that &lt;a href=&quot;http://en.wikipedia.org/wiki/Happy_Air&quot;&gt;Happy Air&lt;/a&gt; only has that one Saab 340 now, but since September all flights are operated by &lt;a href=&quot;http://en.wikipedia.org/wiki/Nok_Air&quot;&gt;Nok Air&lt;/a&gt;, who operates Dash 8 Q400, ATR 72-500, and 737-800 aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-11T21:14:50.903" LastActivityDate="2014-12-11T21:14:50.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11141" PostTypeId="2" ParentId="9822" CreationDate="2014-12-11T19:32:22.037" Score="2" Body="&lt;p&gt;The Langley machine was a disaster, despite its advanced Manly radial engine. Langley had given almost no serious thought to the problems of stability and control. But the Smithsonian shot itself in the foot when it hired Glenn Curtiss to &quot;make a few adjustments&quot; in order to make that machine fly. And Curtiss was indeed sorta successful a decade later, giving rise to the Smithsonian's claim of priority (and a &quot;successful&quot; use of the $50K of taxpayer money Langley had spent!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was this skullduggery which enraged Orville Wright and led to his shipping his Flyer to London. It was only after WWII that the Smithsonian mended its ways with Orville, documenting all the extensive modifications Curtiss had made to the Langley machine, that Orville consented to the return of the 1903 Flyer.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-11T19:32:22.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11142" PostTypeId="2" ParentId="605" CreationDate="2014-12-11T19:52:22.387" Score="2" Body="&lt;p&gt;Performance-wise, a pusher is theoretically better. This is because the high velocity propwash isn't scrubbing over the fuselage or wing, introducing more drag (or &quot;negative thrust&quot; if you like).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, a tractor's propwash is always creating extra drag over downstream surfaces - more drag than if those surfaces simply were scrubbed by the plane's airspeed.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-11T19:52:22.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11143" PostTypeId="2" ParentId="9333" CreationDate="2014-12-11T20:04:00.373" Score="2" Body="&lt;p&gt;When you run up the engine before takeoff, you exercise the prop control. At a fixed throttle setting, move the control from &quot;high rpm&quot; to &quot;low rpm&quot;. The prop blades will take a bigger &quot;bite&quot; on the air, and even though the engine is still producing about the same HP, the rpm will slow way down. It's a case of torque increasing due to the aero loading, and rpm decreasing because of the torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember: high rpm = low pitch, and low rpm = high pitch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Brits say it a little differently: high rpm = fine pitch, and low rpm = coarse pitch. (This is analogous to a fine or coarse pitch on a screw)&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-11T20:04:00.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11144" PostTypeId="2" ParentId="11132" CreationDate="2014-12-11T20:57:06.050" Score="11" Body="&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/11133/65&quot;&gt;Pondlife's answer&lt;/a&gt;, I am contributing some more details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus 380 has room (&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-20131201.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;see page 250&lt;/a&gt;) for potable water tanks which can be added to existing on-board water capacity for showers etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As we know, the showers aren't available for everyone but only for first class, which is probably less than 5% of the total number of passengers, so the water usage is not tremendously huge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Waster consumption and shower duration is also controlled. &lt;a href=&quot;http://www.franke.com/watersystems/aviation/en/home/customized-products/emirates.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Franke&lt;/a&gt; makes the showers for Emirates and states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Low water consumption of less than 5 litres per minute&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When &lt;a href=&quot;http://www.ausbt.com.au/emirates-airbus-a380-first-class-shower-spa-review&quot; rel=&quot;nofollow noreferrer&quot;&gt;75% of the allowed&lt;/a&gt; shower duration is consumed, it shuts down and you have to turn it on again for the remaining 75 seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://www.milevalue.com/emirates-a380-first-class-shower-spa/&quot; rel=&quot;nofollow noreferrer&quot;&gt;first hand account&lt;/a&gt; (including video) of a passenger enjoying the spa.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2014-12-13T14:16:27.637" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11147" PostTypeId="1" CreationDate="2014-12-12T03:08:00.400" Score="10" ViewCount="1044" Body="&lt;p&gt;Suppose you are the captain of Big Jet 345:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Big Jet 345, behind landing Boeing 757, line up runway 27, behind&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Behind landing Boeing 757, line up runway 27, behind, Big Jet 345&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now suppose the landing Boeing 757 executes a go-around. Does the conditional clearance allow you to line up and wait after the Boeing 757 flies over the touchdown point?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="572" LastEditDate="2015-02-19T08:48:04.913" LastActivityDate="2015-02-19T08:48:04.913" Title="Are conditional line-up clearances still valid if the referenced traffic initiates a go-around / missed approach?" Tags="&lt;air-traffic-control&gt;&lt;easa-regulations&gt;&lt;icao&gt;&lt;go-around&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11149" PostTypeId="2" ParentId="11147" CreationDate="2014-12-12T10:46:49.740" Score="9" Body="&lt;p&gt;This may sound obvious, but you should probably ask ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the sentence given it specifies that you should line up behind the Landing B757, not the Going Around B757. This sounds pedantic, but the situation has changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chances are the ATC is still expecting you to be the next aircraft on the tarmac, but if you're in &lt;strong&gt;any&lt;/strong&gt; doubt whatsoever, do not put your aircraft on a live runway (or anywhere else you can reasonably expect another aircraft to want to be in the next 5 minutes) without explicit, unambiguous permission.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2014-12-12T10:46:49.740" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11150" PostTypeId="2" ParentId="11147" CreationDate="2014-12-12T12:13:03.873" Score="0" Body="&lt;p&gt;Whether you are a jet or light aircraft the procedure is the same where conditional lining up is permitted. If an aircraft announces they are going around it's not a landing, so it would not constitute clearance to line up. If you think about it an aircraft may announce a go-around before they reach the threshold, and if you line up there's a potential conflict if the aircraft on approach has an emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, remember you can refuse a clearance if you're not happy with it. Call ATC and ask for instructions, never assume! &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2014-12-12T12:13:03.873" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11151" PostTypeId="2" ParentId="3513" CreationDate="2014-12-12T14:07:02.417" Score="4" Body="&lt;p&gt;The cost impact of a turboprop has been underestimated in many of the earlier answers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbine rotors are subject to very high temperatures while turning at very high rpm; the G-force on a turbine blade is enough to make your eyes water. Due to a minute manufacturing fault or operational error or metal fatigue, one blade lets go; then it will tear through the steel engine case, through any unlucky oil or fuel plumbing, then through the aluminum cowl. The manufacturer will spend hundreds of thousands of dollars to prevent this from happening, and must recover that cost from engine sales.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that's just from one broken blade, weighing maybe a few ounces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a much-heavier rotor disc breaks from fatigue, it could saw the airplane in two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, a turbine burns cheaper fuel, but more gallons than a recip. You can see there are pros and cons!&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-12T14:07:02.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11152" PostTypeId="2" ParentId="3370" CreationDate="2014-12-12T14:31:51.520" Score="2" Body="&lt;p&gt;Airliners must make money, and a LARGE part of their operating cost is fuel. &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;nofollow&quot;&gt;B707s&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-8&quot; rel=&quot;nofollow&quot;&gt;DC-8s&lt;/a&gt; were designed when crude oil was $10 a barrel; so it's obvious why they are now out of the picture. (DC-8s were re-engined as &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-8#Super_seventies&quot; rel=&quot;nofollow&quot;&gt;Super 70s&lt;/a&gt;&quot; in the 1980s with modern &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;nofollow&quot;&gt;CFM56s&lt;/a&gt;, giving lower fuel burn and longer range).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But visit an antique fly-in; planes from the 20s-30s-40s can be seen, showing lots of TLC, better than new! You might see a few antique cars at the same event.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastEditorUserId="65" LastEditDate="2015-01-23T19:30:24.920" LastActivityDate="2015-01-23T19:30:24.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11153" PostTypeId="2" ParentId="572" CreationDate="2014-12-12T14:44:19.267" Score="3" Body="&lt;p&gt;Rapid throttle changes? Skydiving planes see a LOT of shock cooling, and they pay for it at overhaul time. And if you think cylinder heads don't dispose of a lot of heat, look at how cylinder heads evolved through the 30s-40s. The later R-2800 fins are finely machined, quite a contrast to earlier engines with cast fins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And rapid throttle advance can eat you alive in some WWII planes. Many T-6's took their pilots into the weeds on TO. The BT-13 or PT-22 might snaproll if you got in a hurry with the throttle.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-12T14:44:19.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11155" PostTypeId="1" CreationDate="2014-12-12T16:52:24.413" Score="6" ViewCount="3737" Body="&lt;p&gt;We need to replace the fuel tanks on a Cessna 150 and the screws holding the wing cover won't come out. They are just frozen in place. I think that the paint also may be working against us: Getting the paint out of the screw heads has been difficult. So far no screw heads have been rounded off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have any of you had this problem before?&lt;br&gt;&#xA;Also, how is the female part under the skin made? Is it like a j-clip nut that can be replaced, or is the nut part a pressed into the frame?    &lt;/p&gt;&#xA;" OwnerUserId="5529" LastEditorUserId="1696" LastEditDate="2015-02-05T16:43:52.457" LastActivityDate="2015-02-05T16:43:52.457" Title="What is the best way to remove stuck screws from Cessna wing tank cover?" Tags="&lt;aircraft-maintenance&gt;&lt;cessna-150&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11156" PostTypeId="2" ParentId="11155" CreationDate="2014-12-12T17:06:06.717" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;r=PART&amp;amp;n=14y1.0.1.3.21#se14.1.43_13&quot;&gt;FAR Part 43.3&lt;/a&gt; describes who may perform this kind of repair on an aircraft. I recommend you take the plane to such a person who will know exactly how to to perform this repair, and allow the aircraft to remain airworthy &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="64" LastEditDate="2014-12-12T18:49:09.327" LastActivityDate="2014-12-12T18:49:09.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11157" PostTypeId="2" ParentId="11155" CreationDate="2014-12-12T17:49:55.677" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;First the standard disclaimer: If you're in the US and you're not a licensed A&amp;amp;P mechanic, take the plane to your mechanic. (If you're working with your mechanic on this job and helping out by removing the cover plates you've reached the point where it's time to go tap them on the shoulder and ask for help, because the steps to remove frozen screws can do serious damage if you mess up).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Disclaimer over, on with the answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Frozen screws on infrequently-opened access panels are pretty common, and there are a few ways to get them free. You'll note I've drawn a line in this answer: Anything above the line you can probably do on your own, if you have to move to the techniques below below the line let your mechanic do the work (at least until you're confident you can do it without messing up).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Step one&lt;/strong&gt; for removing a frozen screw is to make sure they're not painted in place - you'll need a paint cutter (your mechanic probably has one) and/or an x-acto knife. Cut the paint around the head of the screw using the paint cutter (or the x-acto knife and a very steady hand), and use the x-acto knife to clean out the screw head so your screwdriver can get a good grip.&lt;br&gt;&#xA;Sometimes this is all it takes and the screw comes out on the next try. If not, keep going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Step two&lt;/strong&gt; for removing a frozen screw is to use a &quot;penetrating lubricant&quot; - &lt;a href=&quot;http://www.kanolabs.com&quot;&gt;Kroil&lt;/a&gt; is commonly used, and &lt;a href=&quot;http://www.corrosionx.com&quot;&gt;Corrosion-X&lt;/a&gt; can also do a good job (more about that later). Put a little on each screw and let it work its way into the threads for a while (15 minutes is a good starting point), then try to break the screw loose again. It may take more than one application of penetrating oil to do the job.&lt;br&gt;&#xA;Two notes about penetrating oils: One, they need to be able to get to the threads in order to work (that's why step 1 involves cutting the paint). Two, don't use one that contains silicones (they will embed in the metal grains and make future paint jobs a major pain).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully the penetrating oils will work, otherwise you're going to move on to more destructive processes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Step Three&lt;/strong&gt; involves getting a little more aggressive with the screw in question. Typically by the time you get here you've at least slightly damaged the head trying everything else, so grab a grinder or dremel and cut a flat line into the screw head. This will give you purchase for using a regular (flat-blade) screwdriver, which will hopefully let you apply more torque to the screw. You also want to keep applying penetrating oil while you do this.&lt;br&gt;&#xA;The trick to Step Three is cutting the head deep enough that the blade won't cam out, but not so deep that you compromise the head-to-shank connection in the screw and snap the head off when you try to turn it. This is a bit of an art, so it's best to have your mechanic step in at this point. If you screw up here you're on to step four, and you don't want to get to step four. . . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Step Four&lt;/strong&gt; is drilling the f#!@ing screw out. When all else fails you take a drill right through the screw, demolishing it. Your mechanic almost certainly has appropriate drill bits for this, and the skill to do it without seriously messing up the screw hole / nut plate / cover panel / surrounding skin.&lt;br&gt;&#xA;Even a skilled mechanic may damage rivnuts or nutplates drilling out a screw, and will then have to replace the damaged piece before a new screw can be inserted.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Avoiding the problem in the future&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Once you get the screws out (and your mechanic will - eventually - mechanics always win when screws pick a fight) there are some steps you can take so the next person who has to get this panel off doesn't suffer as much as you did.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Don't paint the screws/panel in place.&lt;/strong&gt;&lt;br&gt;&#xA;If you damage the paint getting the screws out touch it up and let the touch-up cure &lt;em&gt;before&lt;/em&gt; you put the panel/screws back on so the paint isn't acting as a glue holding it all together.&lt;br&gt;&#xA;Also for the love of sanity &lt;em&gt;don't paint the screws&lt;/em&gt; - See #2, and if you repaint the plane do it with this panel &lt;em&gt;off&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Replace the standard screws (probably cad-plated steel) with stainless steel screws.&lt;/strong&gt;&lt;br&gt;&#xA;Stainless screws will corrode, but they're much slower at it than the cadmium-plated steel screws (the cadmium plating that keeps them from rusting in place gets rubbed off as you screw them in). Stainless screws also don't need to be painted like the cadmium-plated ones do, so you won't have to pick paint out of the screw head.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Apply a corrosion treatment before reassembly.&lt;/strong&gt;&lt;br&gt;&#xA;Blast the nutplates/rivnuts/etc. with Corrosion-X or similar - also try to hit any other areas you can reach while the panel is open and things are apart.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Apply a corrosion treatment to the airframe regularly.&lt;/strong&gt;&lt;br&gt;&#xA;Less important if the aircraft is kept in a hangar, but for aircraft tied down on a ramp having a corrosion treatment done every few years will help keep screws from freezing in place.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-12-12T17:57:08.463" LastActivityDate="2014-12-12T17:57:08.463" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11160" PostTypeId="2" ParentId="11155" CreationDate="2014-12-12T21:59:49.670" Score="4" Body="&lt;p&gt;Doing anything with sheet metal fastening systems is extremely delicate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, I would strongly recommend not doing anything mechanical, like use metal scrapers, dremels, gouges or anything like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first step is to use a chemical paint stripper to remove excess paint. Use wood (like a toothpick) if any scraping is involved. Never use a screwdriver to try to gouge out paint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To loosen the screw use heat. I would use a soldering iron of the type used for plumbing. Make sure have a stand for the iron. Do not just lay it on the ground (or worse, on the plane). Touch the iron to the screw to heat it up, then try to unscrew it gently. If one application does not work, use an ice cube to cool it down, then heat it up again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just FYI, this is the way auto mechanics get off tough nuts and screws. They grab a torch and fire away. Obviously, with an aircraft you want to be a lot more delicate, but the principle is the same.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2014-12-12T23:32:06.547" LastActivityDate="2014-12-12T23:32:06.547" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11161" PostTypeId="2" ParentId="10117" CreationDate="2014-12-12T22:07:51.280" Score="-4" Body="&lt;p&gt;I would never use active cancelling for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Simplicity. Doing anything that involves more complexity, batteries, wires, etc, is a bad idea. Keep things simple.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You want to hear everything. The more you hear, the better. If something is wrong with the engine, you want to know that immediately, not find it out later when the plane turns into a brick. The point of the headphones is just to turn down the noise to tolerable levels, not eliminate it. When flying, hearing noises is good.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="65" LastEditDate="2014-12-12T22:17:46.163" LastActivityDate="2014-12-12T22:17:46.163" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11162" PostTypeId="2" ParentId="11147" CreationDate="2014-12-12T22:47:57.527" Score="1" Body="&lt;p&gt;&lt;strong&gt;Europe Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some non-US jurisdictions (such as the UK) it is allowable to issue conditional LUAWs, so the possibility exists that you would have a go-around of the landing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not fly in Europe, but I assume that you normally only move onto the runway AFTER the landing aircraft has touched down. If the aircraft does not touch down (go around), then the LUAW condition is never met, so you do not move onto the runway. The controller would have to issue another LUAW (or departure clearance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;United States Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The example given is not a valid ATC instruction in the United States. A U.S. ATC should NEVER make a &quot;conditional&quot; LUAW. If a tower gives such an instruction, I would confirm it without the illegal conditional. If I heard a tower routinely making conditional LUAWs I would report it, because it is dangerous and a huge violation of FAA departure procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You never line up and wait on the same runway which another aircraft is in the process of landing on, so the &quot;go around&quot; scenario should never happen. If, by some bizarre miscommunication, you think ATC is telling you to LUAW on a runway and you see another aircraft in the process of landing on that runway, you should say &quot;[callsign] holding on [intersection] at [runway #], landing traffic in sight&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that it is dangerous and a serious separation violation for a controller to issue a LUAW when another aircraft is cleared to land on the same runway. If you hear a controller issuing such LUAW it should be reported immediately. Any landing aircraft must be landed and on the ground before a LUAW is given to a departing aircraft on the same runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane is on long final (but has not been cleared to land), and you are given a LUAW on the same runway, the controller MUST inform you of the other aircraft and how far out they are. You may opt to refuse the LUAW based on that information. Under no circumstances will the other aircraft be granted a landing clearance, until you are off the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are unclear about phraseology, you may want to review FAA Departure Procedures.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2014-12-12T23:33:51.497" LastActivityDate="2014-12-12T23:33:51.497" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11163" PostTypeId="2" ParentId="10113" CreationDate="2014-12-13T00:52:49.250" Score="2" Body="&lt;p&gt;Human factors, (cognitive) ergonomics or human-computer interaction have long been a concern in aviation. There are several different approaches (and, in particular, a few distinct national traditions) but, no matter how you want to call that field, there is a lot of attention, resources and research devoted to the interaction between human operators and their flying machines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;“User experience” or “UX design” has now become a rather broad catch-phrase but originally it was mostly meant in opposition to usability engineering and its narrow focus on effectiveness and efficiency. User experience is broader in that it devotes more attention to subjective enjoyment and other intangible factors and also on design (as opposed to assessment and incremental changes), all very interesting aspects of HCI but possibly less relevant to aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usability engineering in turn developed out of human factors (and to some extent in opposition to it as well), quickly focusing on lightweight approaches (“discount usability”), precisely because it was difficult to get as many resources for these concerns outside of traditional industrial domains like power plant control rooms and, yes, aviation (thus closing the loop).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on how you choose to look at it, “user experience” has therefore played a role in human factors all along or is a new(ish) field that grew out of traditional human factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beside the naming issues and history, there are a few major differences between, say, your average website and a cockpit (e.g. users' expertise level, regulatory constraints and company culture) so even if UX design, usability engineering, human factors and cognitive ergonomics are arguably conceptually related, it might be difficult to switch careers or make meaningful contributions to the other field(s) if you have a background in one of them.&lt;/p&gt;&#xA;" OwnerUserId="3018" LastEditorUserId="3018" LastEditDate="2014-12-13T08:02:22.010" LastActivityDate="2014-12-13T08:02:22.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11165" PostTypeId="1" AcceptedAnswerId="11170" CreationDate="2014-12-13T20:28:39.583" Score="3" ViewCount="337" Body="&lt;p&gt;Once in a while an airliner just up and disappears -- typically over ocean -- and lengthy and expensive search efforts have to be launched in order to find it. The most famous cases in recent years were of course AF447 and MH370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard for the bemused public to understand how something as large and technologically advanced as a wide-body jet can just go missing. Some people end up on websites like this one, asking why we can't just do such-and-such to make sure planes can always be found. The answers typically center around how such-and-such would actually be very expensive, and probably not 100% effective anyway. This doesn't &lt;em&gt;really&lt;/em&gt; seem to convince most questioners, who wonder how important a bit of cash ought to be when there are lives at stake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of this question is to clarify whether lives are actually at stake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Suppose we had a magical technology which at negligible cost could give us reliable access to the exact flight path of an airliner in trouble anywhere on Earth. How much safer would that make flying?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For definiteness, let's assume that the magical technology gives us position samples at 1-minute intervals at a one-hour delay, so it won't be useful for real-time purposes such as ATC.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="62" LastEditDate="2014-12-14T23:21:42.610" LastActivityDate="2014-12-14T23:21:42.610" Title="Would better location tracking for airliners improve safety?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;search-and-rescue&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11166" PostTypeId="1" AcceptedAnswerId="11168" CreationDate="2014-12-13T20:37:57.227" Score="16" ViewCount="65759" Body="&lt;p&gt;Before I ask &quot;What does Feathering mean when it comes to Jet/Propeller Engines&quot; I have to say what I think I know:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Feathering jet/prop engines mean achieving a sufficient turbine rotation speed at which, the general functionalities such as VFG drives (elec), pumps, etc. could start operation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would very much appreciate an explanation with any anomalies.&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="572" LastEditDate="2015-02-19T08:46:58.843" LastActivityDate="2017-01-06T10:04:30.500" Title="What does feathering mean and how does it work technically?" Tags="&lt;piston-engine&gt;&lt;propeller&gt;&lt;turboprop&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11167" PostTypeId="2" ParentId="11166" CreationDate="2014-12-13T21:00:00.047" Score="25" Body="&lt;p&gt;Feathering is only possible with variable pitch propellers and means that the blades are turned such that their mid-to-outer section is aligned with airflow and they create minimal air resistance. This is done when the engine is shut down and the propeller should create minimal drag. This means also that all accessories on this engine will not be powered anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the normal twist of a propeller blade, some sections are still not completely aligned with airflow and produce more normal force and drag than they would if all sections could be aligned with airflow at the same time, but in total those forces will cancel out, and the propeller stops windmilling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wY6g2.jpg&quot; alt=&quot;Feathered C-130 prop&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture of a C-130 engine with feathered prop should help to illustrate the concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On pure jets no equivalent setting is possible (we have to wait for variable-pitch fans to add this in the future).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="4474" LastEditDate="2014-12-14T11:31:07.973" LastActivityDate="2014-12-14T11:31:07.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11168" PostTypeId="2" ParentId="11166" CreationDate="2014-12-13T21:00:42.893" Score="25" Body="&lt;p&gt;Feathering is not engine starting, and also is not used in turbine (excluding turboprop) aircraft. In a piston or turbo prop aircraft, in the event of an engine failure, to decrease drag so you can either glide farther or have better performance on the remaining engine(s), you can set the prop pitch lever so instead of facing at a right angle to drive air backwards and produce thrust, the propeller will instead turn edge-first into the airstream, reducing drag. Not all propeller airplanes have this capability, but it's an added safety feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In motorgliders (both light sport aircraft and primary) without retracting blades, the feathering position turns the prop so that the edge faces into the airstream and also locks the propeller so it no longer turns.&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="3504" LastEditDate="2014-12-22T20:52:17.367" LastActivityDate="2014-12-22T20:52:17.367" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11169" PostTypeId="1" CreationDate="2014-12-13T21:09:37.617" Score="4" ViewCount="834" Body="&lt;p&gt;I know that the A380 has low/med/high RTO auto-brakes. What I'm not sure about is if there's a switch near the thrust levers that can disengage the auto-brakes, other than the switches located on the brake panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put it another way, the A380 has a brake panel where the switches allow you to engage/disengage auto-brakes (either low, med, or high RTO). But in addition to those, is there any other switch that can do the same thing without the pilot needing to take his eyes away from the view outside?&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="62" LastEditDate="2014-12-14T01:20:12.370" LastActivityDate="2015-01-06T19:23:08.057" Title="Does the A380 have more than one auto-brake disengage switch?" Tags="&lt;cockpit&gt;&lt;airbus-a380&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11170" PostTypeId="2" ParentId="11165" CreationDate="2014-12-13T21:46:45.667" Score="8" Body="&lt;p&gt;&lt;strong&gt;Would better location tracking for airliners improve safety?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very simply, no.... us knowing where AF447 was would have made exactly &lt;strong&gt;zero&lt;/strong&gt; difference to the fact that it crashed into the ocean at 400+ knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would we have had a better idea of where to find it? Most probably. Would it have saved any lives? Absolutely not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As always, these things come down to cost-benefit, and the simple fact is that GPS tracking would prevent very, very few accidents. The only possible benefit would be that it may help us find the black box or wreckage, assisting in the investigation which &lt;em&gt;may&lt;/em&gt; just &lt;em&gt;possibly&lt;/em&gt; reduce the chances of a similar accident occuring in future. Note that of the two examples you gave, though, only MH370's black box hasn't been found (yet)... so even this benefit is tentative.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="524" LastEditDate="2014-12-14T21:10:18.970" LastActivityDate="2014-12-14T21:10:18.970" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11172" PostTypeId="2" ParentId="572" CreationDate="2014-12-14T02:29:06.737" Score="2" Body="&lt;p&gt;Geared engines - those where the engine drives the propeller through a gearbox so that the engine can turn higher rpms than the propeller - are also susceptible to damage if throttle is reduced too rapidly.  You should never fly these engines so that the prop is driving the engine.  In other words, the airflow through the prop tries to drive the engine to a higher rpm.  Evidently the gear boxes are not built to take the forces in this direction.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while flying a geared engine, throttle must be reduced slowly.  Appropriate use of the prop control lever can also help&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-12-14T02:29:06.737" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11174" PostTypeId="1" CreationDate="2014-12-14T12:29:59.787" Score="12" ViewCount="4530" Body="&lt;p&gt;Yesterday, I saw a strangely-shaped aircraft in the sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Searching for &quot;aircraft silhouette&quot; on the web, I found this picture within seconds on a vector graphics site. It describes perfectly what I saw, so there is nothing else I can say about the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1gkbu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I did not find any information what aircraft it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings are not swept and those stubs at their front look like propeller engines. But it seems as if there are fans at the rear of the fuselage...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, does anybody know what aircraft this is?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@DeltaLima: Not bad. I'm pretty sure that this picture really shows an A-10. The picture is part of a larger one, and the other aircrafts were military ones, too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I saw the aircraft it in Geneva, near GVA airport. Now, I doubt that I saw an A-10 there, as the last A-10 left Germany a while ago, and afaik there are none in Switzerland or France. If I neglect the stubs (which I may have noticed on the picture only), it could also have been  &lt;a href=&quot;https://www.google.de/maps?q=46.236722,6.099500&quot; rel=&quot;noreferrer&quot;&gt;one of those at the GVA airfield&lt;/a&gt;, which have a comparable shape. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 2:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, I'm quite sure that it was one of those labelled A, B, C on this picture from google maps (though, B and C are pretty much the same):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KGWuu.jpg&quot; alt=&quot;air field of geneva airport, taken from google maps&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airfoils as well as the elevator were definitively not (significantly) swept and there was no gap between the airfoils and the fans in the silhouette.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe, it was one of those, maybe, it was a similar aircraft. May be, it really was an A-10.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, this are three 'maybes'. Lets add another:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe, we put this question on hold as there will be no definitive answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But thanks a lot for your contributions!&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2014-12-15T10:33:48.263" LastActivityDate="2014-12-15T10:45:18.640" Title="What aircraft is this?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2014-12-15T14:08:47.173" ContentLicense="CC BY-SA 3.0" />
  <row Id="11175" PostTypeId="2" ParentId="11174" CreationDate="2014-12-14T12:40:13.733" Score="26" Body="&lt;p&gt;It seems to me that it is an  &lt;a href=&quot;http://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II&quot; rel=&quot;noreferrer&quot;&gt;Fairchild Republic A-10 Thunderbolt II&lt;/a&gt;, commonly know as &quot;Warthog&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SqWtN.jpg&quot; alt=&quot;A-10&quot;&gt;&#xA;(Source: wikipedia)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;stubs at the front of the wings&quot; are pods in which the main landing gear is stowed after retraction.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you are in doubt that it was military, it might have been a business jet like the Cessna Citation II / Bravo / Mustang, which has a similar planform albeit without the stubs in front of the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wcwJu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the &lt;a href=&quot;http://www.flightradar24.com/2014-12-13/09:02/12x/46.27,6.19/10&quot; rel=&quot;noreferrer&quot;&gt;replay function of Flightradar 24&lt;/a&gt; you may be able to find out which exact aircraft it was. The coverage at low levels is not so good for all aircraft though. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-15T10:45:18.640" LastActivityDate="2014-12-15T10:45:18.640" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11177" PostTypeId="2" ParentId="10089" CreationDate="2014-12-14T19:51:33.820" Score="0" Body="&lt;p&gt;I am sure all those big twins were towed to their parking position on the inactive runway 11/29, and will be towed back to the factory area when the time comes.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-14T19:51:33.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11178" PostTypeId="1" AcceptedAnswerId="16344" CreationDate="2014-12-14T20:35:34.870" Score="15" ViewCount="9401" Body="&lt;p&gt;What happens to the spinning landing gear right after V&lt;sub&gt;2&lt;/sub&gt; on takeoff? Are they automatically or manually braked to a halt before gear retraction? Or are they allowed to spin to a halt in the wheel wells?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am asking this question in the context of common passenger planes, such as the Boeing 737-800 or the Airbus A320.&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="4197" LastEditDate="2015-09-29T11:52:45.133" LastActivityDate="2019-08-16T14:17:52.873" Title="What happens to the spinning wheels of the landing gear after takeoff, before retraction?" Tags="&lt;takeoff&gt;&lt;landing-gear&gt;&lt;aircraft-systems&gt;" AnswerCount="8" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11179" PostTypeId="2" ParentId="11165" CreationDate="2014-12-14T22:01:42.537" Score="0" Body="&lt;p&gt;In case of a crash/incident where an airliner ends up on the ground, it would allow for faster search &amp;amp; rescue. I.e. lives may be saved since rescue arrives asap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second situation would be in case of an airliner cutting all communication and being used as a weapon (think 9/11). Then tracking would allow ATC/military to keep track of the airliner. But with an 1 hour delay it would probably not be relevant as a preventative measure.&lt;/p&gt;&#xA;" OwnerUserId="988" LastActivityDate="2014-12-14T22:01:42.537" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11180" PostTypeId="2" ParentId="3015" CreationDate="2014-12-14T22:16:18.807" Score="12" Body="&lt;p&gt;Besides ignition keys, small airplanes (single engine land) can be equipped with throttle locks. These metal devices fit over the throttle lever or vernier control and are secured with either a key or a numeric code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've frequently seen this kind of lock on rental aircraft.&#xA;&lt;a href=&quot;http://www.sportys.com/pilotshop/product/12056&quot; rel=&quot;noreferrer&quot;&gt;Here's an example&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TXxb1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="577" LastEditorUserId="65" LastEditDate="2014-12-15T22:35:08.110" LastActivityDate="2014-12-15T22:35:08.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11181" PostTypeId="2" ParentId="3015" CreationDate="2014-12-14T22:48:37.297" Score="5" Body="&lt;p&gt;I think the answer is: it depends. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Citabria has two toggle switches, one for each magneto, and a push button starter. Pilots who have never started one may have trouble because the accepted practice is to put the stick in the crook of your right elbow to keep the elevator back and the tail wheel on the ground, and your right hand on the throttle, which is on the left wall. After flicking on the mags with your left hand high on the right wall, you press the starter button with your left hand. It requires some practice! But I think it might confuse a Cessna driver, or at least make him nose over. Here's a picture of the interior of the LSA version of the Citabria:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/QoUql.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My Mooney has a fancy high-security lock. But even if you have the key, the 270HP engine, turbocharger, and laminar flow wings, not to mention the constant speed prop, cowl flaps, and high V-speeds will prevent even a  777-typed ATP from having a successful solo first flight. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-19T21:01:48.040" LastActivityDate="2014-12-19T21:01:48.040" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11182" PostTypeId="2" ParentId="11178" CreationDate="2014-12-15T00:00:15.510" Score="2" Body="&lt;p&gt;I fly retracts and have heard this question a dozen times. Some people say to tap the brakes, other people (like me) never do. I have asked certified mechanics, and they have all said it doesn't matter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My advice is to follow the POH. If it says tap the brakes, then do so. Otherwise do or don't it doesn't matter. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-15T00:00:15.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11184" PostTypeId="1" AcceptedAnswerId="11186" CreationDate="2014-12-15T06:30:59.727" Score="22" ViewCount="4387" Body="&lt;p&gt;I went on a night flight tonight after not flying for a few months.  I didn't have any monochrome lights, so I actually just covered a flashlight of mine with red athletic tape (which acted as a filter really well).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that using monochrome is the most important thing about preserving night vision - but does it particularly matter, while flying, which color I use? &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2014-12-15T16:41:53.930" LastActivityDate="2017-08-07T16:13:33.410" Title="During night flying, which color lens for a flashlight is most beneficial?" Tags="&lt;night-flying&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11185" PostTypeId="2" ParentId="11178" CreationDate="2014-12-15T08:03:01.930" Score="29" Body="&lt;p&gt;In most common passenger aircraft brakes are automatically applied when the gear is retracted. The wheels stop spinning before they enter the wheel well. This is particularly important because a spinning damaged tire may cause damage to hydraulic and fuel lines which are usually routed near the wheel bay. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose wheels have no brakes, so they are spinning while they are being retracted. Most aircraft have rubber brake pads (snubbers) fitted in the nose gear bay that stop the spinning of the gear once the wheels are retracted. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-12-15T08:03:01.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11186" PostTypeId="2" ParentId="11184" CreationDate="2014-12-15T08:41:28.737" Score="23" Body="&lt;p&gt;You will want to use &lt;strong&gt;red&lt;/strong&gt; light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://biology.stackexchange.com/questions/2075/does-red-light-preserve-your-night-vision&quot;&gt;&lt;em&gt;Does red light preserve your night vision?&lt;/em&gt; on the Biology StackExchange&lt;/a&gt; for a good explanation of the biology and physiology involved, and how it relates to perceptual ability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated in &lt;a href=&quot;https://biology.stackexchange.com/a/2120/1206&quot;&gt;this answer&lt;/a&gt; (by &lt;a href=&quot;https://biology.stackexchange.com/users/560/leonardo&quot;&gt;leonardo&lt;/a&gt;) to that question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If one is exposed to red light (above ~650 nm), it would activate the L-type cones mainly (possibly some M-type activation), but no rod activation. Rods are the low light receptor cells in our eyes, and as such, are very sensitive to the photon density, or brightness, entering the eye.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This is just my speculation, but I think it's plausible that if you were in a completely dark environment with just a red light, filtering out the higher frequencies, night vision could be spared in the sense that we don't activate the rod cells.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="-1" LastEditDate="2017-04-13T12:48:15.740" LastActivityDate="2014-12-16T11:45:37.263" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11187" PostTypeId="2" ParentId="10113" CreationDate="2014-12-15T09:47:49.350" Score="6" Body="&lt;p&gt;My thesis, which I wrote so long ago that I no longer recall the title, was a complete redesign of the Boeing 747 cockpit from a human factors and usability point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My designs, which were submitted to Boeing at the time, likely helped create the foundation for the modern glass fly-by-wire cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the time, glass cockpits did not exist (the term refers to the glass in the CRT monitors that were eventually used within the cockpit, later replaced by LCD displays).  Fly-by-wire, which is the concept of replacing conventional flight controls with an electronic interface, was in its infancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember working tirelessly to create a comprehensive new human interface for pilots that would minimize errors and improve safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My research was based in the cognitive sciences, which consisted of university coursework in human physiology, neuroanatomy (rudimentary at the time), psychology, statistics, engineering, computer science, mathematics, linguistics, neural networks (the very first ones), and artificial intelligence.  It was a rigorous and diverse education.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I spent hours and hours watching films of pilots performing a vast array of different procedures.  Sometimes they were successful, and sometimes they were not.  When they were not, it often resulted in serious consequences.  I spent long nights listening to hour after hour of dialog between air traffic controllers and pilots.  I studied detailed accident and near-accident reports.  I also interviewed pilots and spent a fair amount of time inside commercial cockpits, between flights, gathering essential data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the challenges that I vividly recall was reducing complexity for pilots, while keeping the tasks difficult enough so they would stay engaged to their tasks and not fall asleep or become distracted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most rewarding part of developing my thesis was converting the cockpit from what I called a control-based center to a task-based center.  Up until that time, most controls available to pilots were designed to directly impact a flight control surface such as the rudder.  There were some rudimentary &quot;intelligent&quot; controls to perform basic horizontal and vertical navigation (but nothing that integrated the two!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I designed a new system that was based on high level tasks that the pilot would need to perform.  No longer were ailerons, elevators, flaps, and thrust the focus.  Instead, I changed the focus of the cockpit to center on essential tasks such as taking off, landing, route planning, communications, and traffic and weather avoidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this work, I learned that I had to seamlessly integrate my human factors engineering and user experience design skills.  In my opinion, and from my personal experience, they always need to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whenever I fly, I ask to take a look at the cockpit after we land.  It's a joy to see the evolution of my designs.  Whether I was the originator of these designs or one of many human factors engineers who came up with them at the same time, I will never know.  But similarities of the current designs to what I proposed in my thesis many years ago gives me a little insight into a possible answer to that question.&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="64" LastEditDate="2014-12-16T06:17:24.637" LastActivityDate="2014-12-16T06:17:24.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11188" PostTypeId="2" ParentId="1456" CreationDate="2014-12-15T13:04:26.877" Score="0" Body="&lt;p&gt;My own experience with flight following, from operating out of both towered and non-towered fields in the Carolinas:  After taking off on an XC from my non-towered home field, depending on my heading, I contact the nearest approach control, for example, Wilmington NC (KILM) or Myrtle Beach (KMYR). Before taking off from a towered airport, I will ask the ground controller for FF and get a squawk code and post-departure contact frequency. (ATIS at some of airports I have flown into include instructions for requesting FF); to back that up, if I have not already requested FF, ground or tower controller may be proactive and offer it to me.  Airspace around busy airports can be crowded, and I feel safer knowing that I am not an unidentified blip; ATC knows where I am, and what I am doing, and can redirect me if necessary. Positive communication is key to staying safe.&lt;/p&gt;&#xA;" OwnerUserId="5544" LastActivityDate="2014-12-15T13:04:26.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11189" PostTypeId="2" ParentId="3300" CreationDate="2014-12-15T13:19:49.153" Score="7" Body="&lt;p&gt;Below is the info about one of the early prototypes by Paul Moller, author of the 'Volantor', too, now the head of Freedom-Motors, a company focused on Wankel Rotary Combustion Engines. Moller built his flying machines with fans driven by Wankel rotary engines, however, it sounds better having electrical engines for lifting and  propulsion fans, and some kind of hybrid system for generating power, Wankels are very good in weight to power ratio and safety. I'd say the Moller and Helikar are exactly a Quadcopter, and as this machine, and the Utility model/patent backing it are from earlier times as the toys we all know, probably it was the chicken of contemporary toy Quadcopters, the today toys being the eggs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rope and the crane behind the Moller: 'flying saucer', Avro Canada failed in having one airborne, are not for keeping the machine in the air, but a safety measure, if you look, you'll notice that the rope is not under tension while the machine on the air, meaning that the machine flies by itself, and is not hung on the crane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The prototypes Bell Textron/X-22 and Curtiss-Wright X-19 can be considered also very close to a quadcopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Spanish team: FuVex, designed a prototype named: 'HeliKar', also close to a big size Quadcopter. YouTube includes a video about a German invention named: 'Volocopter VC200', Terrafugia proposed another 'Flying Car', as well as Zee. Aero did, they draw a concept VTOL flying car that could be parked between two ordinary cars in a mart parking lot (see: 'SlashGear'). Aero-X by Aerofex is another one. Fipsi is involved in developing a four-fan flying car, as cited in 'Advanced System Engineering', SUSB Expo 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;'Future transportation' cites what they consider: 'The top 10 flying cars'. Krossblade proposed the SkyProwler and the SkyCruiser, the big problem in a flying car seems fulfilling in the same design the weight and safety requirements for both a car and an airplane. Ford released drawings for an: 'Aero-car'. CNN reports about Fly Citycopter, by E Galvani.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mechanix Illustrated, March 1957 includes a: 'Flying saucer', design by Peter Nofi, power comes from a flat-six reciprocating engine, and Popular Mechanix, French editon, Sept 1961, a similar design: 'Rotavion', by Ben Kaufman. &#xA;Mechanix Illustrated, Jan 1962, pp 70-73, is about a VTOL device having 3 shrouded fans moved by a turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding historical precursors, the machine in the 1961 movie by William Witney: 'Master of the World', based on two novels by Jules Verne: 'Master of the World', and: 'Robur the Conqueror', could be easily considered as a Multi-propeller: 'Quadcopter'. If: 'Fly by wire', succeeded in keeping airborne intrinsically unstable and unsteerable designs, there can be no limits in what could be accomplished with a digital control technology that currently is sold in toys starting at around $20.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Hungary based company: 'Flike', and Hungary's name doesn't come from 'Hunger', but from: 'Huns', just presented a 'piloted' three propeller copter, video is signed by Bay Zoltan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do the flying platforms, single person devices, ducted fan below, tested by the US Army, belong to the: 'Quadcopter' class?. Also, several 'tilting wings' and annular wing flying machine arrangements were tested, the list of 'Concept' and 'Unconventional' aircraft paves the way for many books, but the web is killing this type of paper publications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;'SkyProwler', is another approach, a mixed Quadcopter and fixed wing design.&#xA;Bensen B-12 (see 'Aerofiles') is a 1961 example of Multi-Rotor (rather multi-propeller) Quadcopter style machine, patent US49820151 is about the multi fan P. Moller's design, and patent CA1264714 is about a: 'Robotic or remotely controlled flying platform', also by P. Moller. All patents are of open and free access and download in: 'Espacenet'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason why Quadcopter toys couldn't be increased in size, even using the same software for controlling engines and stability?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks.  + salut&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/GKuDJr-feSk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Moller M200 test flight&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://youtu.be/oEoly6BSJWc&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helikar&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://youtu.be/h7aIXvyBC64&quot; rel=&quot;nofollow noreferrer&quot;&gt;P2 Hoverbike from Malloy Aeronautics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QrQcS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QrQcS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N3iJC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N3iJC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="21763" LastEditDate="2020-06-15T16:37:24.937" LastActivityDate="2020-06-15T16:37:24.937" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="11190" PostTypeId="2" ParentId="11184" CreationDate="2014-12-15T15:17:12.427" Score="11" Body="&lt;p&gt;I know everyone is going to say you need a red light, and that should be your primary light.   But I think its important to also have a white light and one other color (typically green).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is simply that red light makes everything look red, and makes it hard to distinguish colors!  Can you actually verify that the AVgas is light blue when you look at it under a red light?  Can you see bright red, important items on a checklist?  Reading red-text against a white background can be very difficult with a red light.  On a VFR map, airport symbols are blue or magenta to indicate towered/untowered airports, but they both look the same under a red light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while your primary light should probably be red, you'll need alternate colors and plain-old white for many things.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2017-08-07T16:13:33.410" LastActivityDate="2017-08-07T16:13:33.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11192" PostTypeId="2" ParentId="1926" CreationDate="2014-12-15T20:48:21.120" Score="3" Body="&lt;p&gt;There will be no exemptions for the CPDLC rule in the North Atlantic Track area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Datalink Mandate will be implemented:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;starting 5 February 2015: FL350 to FL390 (inclusive) on all tracks within&#xA;the NAT Organized Track System (OTS)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;starting 7 December 2017: FL350 to FL390 (inclusive) throughout the ICAO&#xA;NAT region.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;starting 30 January 2020: FL290 and above throughout the ICAO NAT region.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;ATS Surveillance Airspace, airspace north of 80°N and the New York FIR are excluded from the mandate. &#xA;This means that aircraft equipped with a suitable transponder / ADS-B transmitter will be able to cross using the Canada - Greenland - Iceland ADS-B corridor without having to carry FANS 1/A equipment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3OFWc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-15T21:02:37.150" LastActivityDate="2014-12-15T21:02:37.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11193" PostTypeId="2" ParentId="8900" CreationDate="2014-12-15T20:57:53.140" Score="5" Body="&lt;p&gt;Sample of two engine uncontained failures:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_32&quot; rel=&quot;nofollow&quot;&gt;Qantas Flight 32&lt;/a&gt;: departing Singapore Nov. 2010&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow&quot;&gt;United Airlines Flight 232&lt;/a&gt;: over Iowa, July 1989&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In both cases, large chunks of rotor discs &quot;went missing&quot;. Had they hit someone, it would surely be fatal. Extensive searches were conducted, because they were important in the forensic analysis.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastEditorUserId="65" LastEditDate="2015-07-02T14:43:30.160" LastActivityDate="2015-07-02T14:43:30.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11194" PostTypeId="2" ParentId="8649" CreationDate="2014-12-15T23:12:26.547" Score="2" Body="&lt;p&gt;From the 30s to the 60s, the standard for transoceanic travel was a 4-engine aircraft. If you'd asked certain airlines if they'd buy a 3-engine Lockheed or Douglas airliner, they'd say &quot;NO&quot; because their customers would refuse to fly with less than four engines!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But gradually 3 engines became standard for oceanic travel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And in the early 80s, &lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow&quot;&gt;ETOPS&lt;/a&gt; came along because engines had become extremely reliable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the design process is evolutionary; most changes happen pretty slowly, and designers often copy the successes of other designers.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastEditorUserId="65" LastEditDate="2014-12-17T21:06:33.593" LastActivityDate="2014-12-17T21:06:33.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11196" PostTypeId="1" CreationDate="2014-12-16T11:25:04.717" Score="2" ViewCount="315" Body="&lt;p&gt;How many VHF (Voice Communication) system can be in MEL for A340 aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the guidelines to decide that and is it different for aircraft operating under FAR 121, 125 and 135?&lt;/p&gt;&#xA;" OwnerUserId="5543" LastEditorUserId="65" LastEditDate="2014-12-16T15:38:31.343" LastActivityDate="2014-12-16T15:38:31.343" Title="How many VHF system can be in MEL for an A340?" Tags="&lt;radio-communications&gt;&lt;avionics&gt;&lt;commercial-operations&gt;&lt;radio&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11197" PostTypeId="2" ParentId="11196" CreationDate="2014-12-16T15:38:05.147" Score="1" Body="&lt;p&gt;There are three VHF systems on A340 aircraft, as &lt;a href=&quot;http://fsims.faa.gov/wdocs/mmel/a340-200-300%20original%2005-30-08.htm&quot; rel=&quot;nofollow&quot;&gt;described here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Item:&lt;/strong&gt; VHF Systems&lt;br/&gt;&#xA;  &lt;strong&gt;Number Installed:&lt;/strong&gt; 3&lt;br/&gt;&#xA;  &lt;strong&gt;Number Required for Dispatch:&lt;/strong&gt; -&lt;br/&gt;&#xA;  &lt;strong&gt;Remarks or Exceptions:&lt;/strong&gt; Any in excess of those required by FAR may be inoperative provided it is not powered by an Essential Bus and not&#xA;  required for emergency procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Master_minimum_equipment_list&quot; rel=&quot;nofollow&quot;&gt;MMEL is required by FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A minimum equipment list is required in the United States by the&#xA;  Federal Aviation Administration:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;When operating any turbine-powered aircraft such as jets or turboprops.&lt;/li&gt;&#xA;  &lt;li&gt;When operating under part 135 (Commuter and on-demand operations)&lt;/li&gt;&#xA;  &lt;li&gt;When operating under part 125 (Non-airline large aircraft operations)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;MEL for FAR 121 is &lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v04%20ac%20equip%20&amp;amp;%20auth/chapter%2004/04_004_008.htm&quot; rel=&quot;nofollow&quot;&gt;discussed here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2014-12-16T15:38:05.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11199" PostTypeId="1" AcceptedAnswerId="11200" CreationDate="2014-12-16T17:32:31.543" Score="10" ViewCount="3605" Body="&lt;p&gt;I have gone through this &lt;a href=&quot;https://aviation.stackexchange.com/q/9722/65&quot;&gt;post&lt;/a&gt; which explained me why there are red lights turned on the plane but I doubt with the color code whether it's only during the environment specific conditions or its indication that it is relaying coordinates?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every time one thing caught my attention during my flight journey. During the specific time of the day the lights on the wings changed with color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On one flight it had a white constant blinking. This flight was during the day. The blinking was slow and repeated up to thrice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EbvjM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the second flight, there was a blinking green light along with the blinking white light. This blinking was fast so I couldn't get a clearer shot and this is during sunset.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lnLZ1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note:-In the above two images both are of the Airbus A320 Sharklet. I believe it has something to do with tracking and relaying the coordinates to the ATC.&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-29T14:20:57.827" Title="Do lights on wingtips change color at different times of the day?" Tags="&lt;aircraft-systems&gt;&lt;aircraft-lighting&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11200" PostTypeId="2" ParentId="11199" CreationDate="2014-12-16T17:45:46.767" Score="21" Body="&lt;p&gt;Every plane has green and white lights on the right (starboard) wing, as in this photo, and red and white on the left (port) wing. These lights are called &quot;navigation lights,&quot; and are the same as are used in boating. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The green and red lights are always on, no matter what, and are used to help other aircraft know which direction the aircraft is going, based on whether the other pilot sees red, green or both lights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The white lights are also on all the time, and flash constantly. These lights are called &quot;anti-collision lights.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/brH0f.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/1/13/Jet-liner%27s_lights_1_N.PNG&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you are actually seeing is the green light constantly on, and the white flashing - but because the white is so much brighter and is flashing, it's more apparent than the green (which, especially in the day, is fairly dim)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At night, the green becomes more obvious and the flashing white becomes more visible. The flashing white over-powers the green, which gives an optical illusion that the Green is flashing. The reality is that the Green is always on, and the white is flashing.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="643" LastEditDate="2014-12-17T20:33:17.947" LastActivityDate="2014-12-17T20:33:17.947" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11203" PostTypeId="2" ParentId="3015" CreationDate="2014-12-16T21:05:40.690" Score="4" Body="&lt;p&gt;Some business jets like the Gulfstream for instance have a key to lock your passenger door from the outside, for instance if your aircraft is in night halt or you're gonna leave the aircraft parked for a day or so... it's mainly for the security of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most commercially used aircraft like Airbuses, have a CDSS (Cockpit Door Surveillance System), which allows the flight crew to see who is trying to access the cockpit door from the cabin. Most of the time, a cockpit door with CDSS has a unique password to be entered on the touchpad of the cockpit door (at the entrance to the cockpit from the cabin) to get access to the flight crew compartment. These passwords are normally known to the cabin crew and flight crews only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial aircraft normally do not have a door key to lock it from the outside as its security is monitored by airport security staff.&lt;/p&gt;&#xA;" OwnerUserId="5543" LastEditorUserId="97" LastEditDate="2014-12-18T14:34:50.170" LastActivityDate="2014-12-18T14:34:50.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11204" PostTypeId="1" CreationDate="2014-12-16T21:18:41.153" Score="6" ViewCount="658" Body="&lt;p&gt;For a hobbyist looking to write an autopilot program for a mode lUAV/drone, what are the aviation related considerations that would be involved in its design?  How could things like the ADC (air data computer), or pitot static system, be utilized to control bank angles and decent rates?  Are there any specific rules of thumb that would assist the autopilot in making smooth corrections?  For example, how should I calculate the max VSI in a climb or when approaching a level-off altitude, and is there a rule of thumb for bank angle in a turn?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your answers will guide me in asking an educated question at the Programmers StackExchange and get programming specific advice on how to proceed.&lt;/p&gt;&#xA;" OwnerUserId="5556" LastEditorUserId="4215" LastEditDate="2014-12-17T01:14:01.383" LastActivityDate="2014-12-17T01:14:01.383" Title="Write my own autopilot software" Tags="&lt;autopilot&gt;&lt;unmanned-aerial-vehicle&gt;&lt;software&gt;" AnswerCount="0" CommentCount="12" FavoriteCount="1" ClosedDate="2014-12-16T22:26:06.347" ContentLicense="CC BY-SA 3.0" />
  <row Id="11206" PostTypeId="1" CreationDate="2014-12-17T04:53:20.177" Score="3" ViewCount="192" Body="&lt;p&gt;I want to build some software containing information about aircraft, like a logbook. Nothing related with avionics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that default language in the aviation industry is English, but in the case of online software, could professionals be interested in using an online logbook or MRO software showing in another language besides English?&lt;/p&gt;&#xA;" OwnerUserId="2130" LastEditorUserId="97" LastEditDate="2015-04-22T00:42:39.673" LastActivityDate="2015-04-22T00:42:39.673" Title="Is aviation software translated into the users' native language desirable over English?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;&lt;commercial-operations&gt;&lt;software&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11207" PostTypeId="2" ParentId="4966" CreationDate="2014-12-17T06:26:29.473" Score="6" Body="&lt;p&gt;Further to above answer.., &#xA;&lt;strong&gt;Check out this link to see inside of an engine &lt;a href=&quot;http://animagraffs.com/inside-a-jet-engine/&quot;&gt;http://animagraffs.com/inside-a-jet-engine/&lt;/a&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbofan is the most efficient engine and most of the thrust is produced from the bypass air. The efficiency of the engine mainly depends on the engine bypass ratio. Turbojet is mainly used on the fighter or acrobatic aircraft. These aircraft’s thrust is further increased by the “after burner” installed at the nozzle of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbo propellers are efficient on the short overhaul operation and the a/c with turbo props requires only shorter runway to achieve the required lift compared to other types.&#xA;Turbo shaft, is the engine mainly used on the helicopter and the energy comes out of the turbine is used by the rotor to achieve the required rpm.&lt;/p&gt;&#xA;" OwnerUserId="5543" LastEditorUserId="5543" LastEditDate="2014-12-18T05:49:12.410" LastActivityDate="2014-12-18T05:49:12.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11208" PostTypeId="2" ParentId="11206" CreationDate="2014-12-17T06:47:45.010" Score="2" Body="&lt;p&gt;English is the native language of aviation... &lt;br/&gt;&#xA;I myself always get mightily annoyed at poorly translated software, which is 90% of all software provided in multiple languages. IF you provide multiple languages, allow the user to switch between them AND get professional translators to do the work.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Would it sell? Probably, if it's good enough. But I don't see the language options as being a major selling point. Certainly not so big that having them will make a large number of potential customers choose it over another product that has more options elsewhere but lacks language selection.&lt;br/&gt;&#xA;In some places maybe, where English is less than common and not generally used by ATC.&lt;br/&gt;&#xA;Whether that's where your intended market is I don't know.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2014-12-17T06:47:45.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11210" PostTypeId="1" CreationDate="2014-12-17T12:16:36.243" Score="-3" ViewCount="322" Body="&lt;p&gt;I am interest in how much computer data is required in building the 747&gt;&lt;/p&gt;&#xA;" OwnerUserId="5561" LastActivityDate="2014-12-17T13:39:59.047" Title="How much data required in the 747 design?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2014-12-17T15:05:37.403" ContentLicense="CC BY-SA 3.0" />
  <row Id="11211" PostTypeId="2" ParentId="11210" CreationDate="2014-12-17T13:39:59.047" Score="5" Body="&lt;p&gt;The 747 was designed in the 1960s (rollout in September 1968) so a rather simplistic answer to &quot;how much computer data...&quot; is none. The design would have been done on manual drafting tables using slide rules and mechanical calculators, with actual computers only used for the occasional complex calculation assuming they didn't crash in the process. These calculations would have produced a single value or small set of values, not a finished design by modern standards&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are possibly thinking of the 777 design process. This was the first Boeing product designed entirely with CAD systems. They use CATIA by Dassault, the details are not readily available but I think we can assume that the amount of data involved is Large. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-12-17T13:39:59.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11212" PostTypeId="1" AcceptedAnswerId="11214" CreationDate="2014-12-17T17:24:18.713" Score="9" ViewCount="1413" Body="&lt;p&gt;How does a hobby weather balloon control its flight path? Just it just keep rising straight up vertically, always at the mercy of the winds, being swayed side to side?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike a rocket/drone, it does not have an engine/motor that can be controlled remotely. So if I want the balloon to hover over a particular area and send me images (a particular section of a forest to watch for wildlife activity), how do I do it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All weather balloons seem to be aimed towards gaining altitude and taking NASA like images, but is there a way to move a balloon horizontally and not just vertically&lt;/p&gt;&#xA;" OwnerUserId="5556" LastEditorUserId="1467" LastEditDate="2016-05-25T10:38:29.370" LastActivityDate="2017-07-28T15:02:45.383" Title="Can a weather balloon move horizontally?" Tags="&lt;balloon&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11214" PostTypeId="2" ParentId="11212" CreationDate="2014-12-17T19:03:13.423" Score="7" Body="&lt;p&gt;An ordinary weather balloon cannot maneuver horizontally (unless an external force is applied to it) because it lacks the means to do that. It has only one purpose, to soar up to the altitude where the air pressure inside is more than outside and then burst.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want it to steer, you can add steering servos (&lt;a href=&quot;ftp://ftp.tik.ee.ethz.ch/pub/students/2013-FS/SA-2013-02.pdf&quot; rel=&quot;noreferrer&quot;&gt;as mentioned in this PDF&lt;/a&gt;). Of course this will add cost and complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some websites for &lt;a href=&quot;http://weather.uwyo.edu/polar/balloon_traj.html&quot; rel=&quot;noreferrer&quot;&gt;Balloon Trajectory Forecast&lt;/a&gt;, which might be helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only if &lt;a href=&quot;http://en.wikipedia.org/wiki/Larry_Walters&quot; rel=&quot;noreferrer&quot;&gt;Larry Walters&lt;/a&gt; had thought about this, things would have been different for him.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-17T21:07:31.400" LastActivityDate="2014-12-17T21:07:31.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11215" PostTypeId="2" ParentId="11178" CreationDate="2014-12-17T20:18:26.760" Score="1" Body="&lt;p&gt;Follow the POH is always the best and most correct answer because it is different on different models and types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a 1971 C177RG POH in front of me right now and it says:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing Gear Retraction&#xA;Before retracting the landing gear, the brakes should be applied momentarily to stop wheel rotation&lt;/p&gt;&#xA;" OwnerUserId="5565" LastActivityDate="2014-12-17T20:18:26.760" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11216" PostTypeId="2" ParentId="11212" CreationDate="2014-12-17T22:07:49.180" Score="2" Body="&lt;p&gt;A weather balloon is almost constantly moving horizontally.  The only time it is not moving horizontally is when there is no wind and the balloon has no horizontal momentum (gained from rising through layers with horizontal winds).  You cannot control this horizontal motion and the balloon is at the mercy of the wind.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a platform that is in control of its position, you will need something that can provide its own thrust.  A weather balloon is not going work for that application.  A weather balloon is also not designed to hover, but to rise until it bursts somewhere around 100,000 ft.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2014-12-17T22:07:49.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11217" PostTypeId="1" AcceptedAnswerId="11232" CreationDate="2014-12-17T22:50:38.703" Score="16" ViewCount="7414" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/D97FA35A1232A3988625768F005C12DE?OpenDocument&quot;&gt;FAR 91.205(b)(8)&lt;/a&gt; says that you need a manifold pressure gauge for each &quot;altitude engine&quot;, whatever that means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What's an &quot;altitude&quot; engine?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2019-04-30T17:35:38.863" Title="What's an &quot;altitude engine&quot;?" Tags="&lt;terminology&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11218" PostTypeId="2" ParentId="11217" CreationDate="2014-12-17T22:50:38.703" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/A16147FC43C4F9B286257A9500451B45?OpenDocument&quot;&gt;FAR 1&lt;/a&gt; says that an &lt;em&gt;altitude engine&lt;/em&gt; is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a reciprocating aircraft engine having a rated takeoff power that is producible from sea level to an established higher altitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, if you can develop sea level power at an altitude higher than sea level, you've got an altitude engine.  Generally, this means you're flying with a boosted engine (whether the boosting comes from a turbo, a supercharger, or something else).&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-12-17T22:50:38.703" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11219" PostTypeId="1" AcceptedAnswerId="11224" CreationDate="2014-12-18T00:05:44.447" Score="7" ViewCount="1739" Body="&lt;p&gt;Cargo planes secure their load meticulously and if it breaks loose, the result is sometimes &lt;a href=&quot;https://www.youtube.com/watch?v=lksDISvCmNI&quot;&gt;catastrophic&lt;/a&gt;. However, how do you prevent fuel sloshing inside the tanks and causing the same problems as loose cargo?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-10-30T12:32:36.337" Title="Can fuel sloshing in the tanks cause a stall?" Tags="&lt;stall&gt;&lt;cargo&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11220" PostTypeId="2" ParentId="11219" CreationDate="2014-12-18T01:46:01.943" Score="10" Body="&lt;p&gt;There are dividers (baffles) in the fuel tank precisely to stop the sloshing. They are just large plates that will stop the fuel from flowing across.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High maneuver jets will use bladder tanks (so no air is in the tank with the fuel) as a way to contain the fuel.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="595" LastEditDate="2015-10-30T12:32:36.337" LastActivityDate="2015-10-30T12:32:36.337" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11221" PostTypeId="2" ParentId="11169" CreationDate="2014-12-18T06:08:34.857" Score="9" Body="&lt;p&gt;The A380 has one Takeoff Autobrake setting which is RTO and five Landing Autobrake settings which are BTV, LO, 2, 3 and HI. Some may read that as four plus the BTV, which is a variable deceleration compared to fixed deceleration. As you have noted, these are selected from the Autobrake selector switch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to disarm the Autobrake using a number of actions. One or two which have been mentioned already.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The Autobrake selector switch is set to Disarm.&lt;/li&gt;&#xA;&lt;li&gt;The Brake pedals are depressed with a higher input than the Autobrake setting.  &lt;/li&gt;&#xA;&lt;li&gt;The Spoilers are retracted.  &lt;/li&gt;&#xA;&lt;li&gt;The Autothrust instinctive disconnect pushbutton switch is pressed. These are located at the ends of the Throttle control levers.  &lt;/li&gt;&#xA;&lt;li&gt;The RTO Arm pushbutton switch is set.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;FCOM Reference for anyone interested - FCOM/DSC/32/10/30/20/00004244.0002001&lt;/p&gt;&#xA;" OwnerUserId="4435" LastEditorUserId="65" LastEditDate="2015-01-06T19:23:08.057" LastActivityDate="2015-01-06T19:23:08.057" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11224" PostTypeId="2" ParentId="11219" CreationDate="2014-12-18T09:25:21.103" Score="10" Body="&lt;p&gt;The answer is no, but some shifting of the center of gravity (c.g.) due to attitude is unavoidable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tanks are subdivided so the c.g. shift within a single tank is small. You can notice the sloshing after a landing when the aircraft has come to a complete stop after taxiing: It will gently rock back and forth due to the sloshing in the tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some fighter aircraft use a sponge-like mesh in their tanks which is very effective in breaking up sloshing. It takes up approx. 2% of internal volume. However, in a nose-up attitude the fuel will still collect at the back of the tanks, and again only distributing fuel over several tanks will prevent a significant c.g. shift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Subdividing also helps in spanwise direction to prevent high loads on wing ribs when the aircraft rolls. Remember, an F-16 has a top roll rate of 720°/s, which creates a significant inertial pressure on the wing's tank walls.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-18T10:36:41.477" LastActivityDate="2014-12-18T10:36:41.477" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11225" PostTypeId="1" AcceptedAnswerId="11226" CreationDate="2014-12-18T13:42:56.440" Score="13" ViewCount="3424" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/7802/when-the-brakes-are-checked-what-do-the-firemen-actually-do&quot;&gt;this question&lt;/a&gt;, our intrepid former 747 pilot Terry mentioned, in the accepted answer, that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As I understand it, tires that dangerously overheat will explode before melting, and that's why thermal plugs are used which melt and deflate the tire to prevent their exploding.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;His understanding was confirmed by other comments and answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is what is the net difference between a tire deflating due to the plug melting and the tire deflating due to explosion? Either way, you're landing/taxiing with a flat tire. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing that comes to mind is that once the plane is on the ground and stopped, an exploding tire might injure safety crews and/or pax evacuating.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-02-23T21:33:40.330" Title="What is the difference between a tire deflation and a tire explosion?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;boeing-747&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11226" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T13:53:59.660" Score="19" Body="&lt;p&gt;An exploding tire while the plane is rolling will propel debris in various directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This happened with the &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_4590&quot;&gt;crashed Concorde&lt;/a&gt; on takeoff. A chunk of the tire hit the tanks and caused a punctured in it. This then lead to the fire and loss of power.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2014-12-18T13:53:59.660" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11227" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T13:58:56.380" Score="16" Body="&lt;p&gt;&lt;strong&gt;An explosion creates debris&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft, &lt;a href=&quot;http://en.wikipedia.org/wiki/Foreign_object_damage&quot; rel=&quot;nofollow noreferrer&quot;&gt;Foreign Object Damage&lt;/a&gt; is a big concern and an exploding tire would be a major source of FOD. This would be a concern to the landing aircraft itself as its engines might suck in the debris of a blown tire, and it would be a concern to other aircraft as tire fragments can be blown all over the runway and might in turn be ingested by the next aircraft landing or taking off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;An explosion might damage the aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft tires are &lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/jet-aviation-on-rough-airfields/7496#7496&quot;&gt;inflated to very big pressures&lt;/a&gt; so the explosion itself or the speed of the fragments might be enough to cause severe damage to the aircraft systems or fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Explosions are dangerous to people around the aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft lands at speeds that could cause the tires or brakes to overheat, firefighters &lt;a href=&quot;https://aviation.stackexchange.com/a/7814/5570&quot;&gt;will inspect the brakes and tires&lt;/a&gt; of aircraft that have landed and might have overheated the tires or brakes. With thermal plugs the pressure in an overheated tire will be vented in a controlled fashion (the firefighters can predict the direction of the vent) so it's less of a safety issue.&lt;/p&gt;&#xA;" OwnerUserId="5570" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-12-19T13:29:24.937" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11228" PostTypeId="2" ParentId="11212" CreationDate="2014-12-18T14:15:32.407" Score="5" Body="&lt;p&gt;Yes, I think a balloon can move horizontally the same way a cloud can (by wind).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;if I want the balloon to hover over a particular area and send me images (a particular section of a forest to watch for wildlife activity), how do I do it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think I've got a simple answer to this one: Use a rope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least for a small balloon that's only 1 or 2 hundred feet up you could let it rise up like a kite and tie it off over your desired area. You might even be able to use a security camera wire to enable using a (relatively) cheap security camera, sending power &amp;amp; video up &amp;amp; down the wire, instead of a wireless camera. And you'll have the desirable ability to pull it back down to retrieve camera easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, if you're thinking of using a giant weather balloon 1000+ feet in the air, I think that would create a hazard to aviation. [Does anyone know of any regulations or laws if that would be illegal anywhere? Canada/US/Europe?]&lt;/p&gt;&#xA;" OwnerUserId="4506" LastActivityDate="2014-12-18T14:15:32.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11229" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T16:06:50.487" Score="6" Body="&lt;p&gt;An exploded tire cannot be reused.  A deflated tire, after relevant inspections, can be reused.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, you will need a new fusible plug but that is a lot less expensive than a new tire.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-12-18T16:06:50.487" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11230" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T16:38:04.217" Score="6" Body="&lt;p&gt;An exploding tyre throws heavy tyre fragments in all directions at high speeds. Fragments might damage the plane but they also might kill anybody nearby, such as emergency services personnel, ground crew and passengers.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-12-18T16:38:04.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11231" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T16:47:02.327" Score="12" Body="&lt;p&gt;You are right that a main reason for fuse plugs is safety of people nearby.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surrounding structure is generally reinforced to protect against tires bursting, but if it bursts while stationary it can cause damage and will send debris in a different pattern than it would if it were moving (which is when tires usually burst).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also relates to fire safety. An exploding tire can spread burning liquid or debris.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tires spend most of the flight inside the wheel well. Under normal conditions, brakes will be hottest after landing, and would be allowed to cool down after a rejected takeoff, so the tires should not be excessively hot when retracted. Systems and structure in the wheel well is reinforced, but &lt;a href=&quot;http://en.wikipedia.org/wiki/Nigeria_Airways_Flight_2120&quot;&gt;fires are possible&lt;/a&gt;, and an exploding tire in the wheel well can certainly cause damage.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-18T18:34:07.810" LastActivityDate="2014-12-18T18:34:07.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11232" PostTypeId="2" ParentId="11217" CreationDate="2014-12-18T16:51:01.710" Score="16" Body="&lt;p&gt;An &lt;em&gt;altitude engine&lt;/em&gt; is a type of engine that uses a &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbocharger&quot; rel=&quot;nofollow noreferrer&quot;&gt;turbocharger&lt;/a&gt; (and less often, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Supercharger&quot; rel=&quot;nofollow noreferrer&quot;&gt;supercharger&lt;/a&gt;) to generate sea-level pressure in its intake manifold, up to its critical altitude, at which point power will start to fall off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Non-altitude engines&lt;/em&gt; will lose power as they climb because the ambient air pressure drops off at a rate of about 1&quot; Hg per 1,000 ft of altitude (up to 10,000ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude engine allows aircraft to fly at higher altitudes at full power, and increases the aircraft's speed and efficiency, because true airspeed increases with altitude. It also allows an aircraft under IFR to fly at higher MEAs or under VFR over higher terrain, and allows the pilot to choose a favorable altitude for weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first kind of altitude engine is called a &lt;em&gt;turbocharged engine&lt;/em&gt;, which can generate more intake manifold pressure than at sea level. For example, a Mooney Bravo M20M can generate 36&quot; of manifold pressure, and can generate at least 30&quot; of manifold pressure up to its critical altitude of 22,000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other kind of altitude engine is called a &lt;em&gt;turbo-normalizer&lt;/em&gt;, which develops a maximum of sea level pressure: 30”Hg or 1 Bar. These engines will perform as well at altitude (up to their critical altitude) as they do at sea level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A turbo-normalized engine is considered less taxing on the engine than a turbocharged engine because the former doesn't develop above sea-level pressure or high turbine-inlet temperatures. The turbo-normalized engine is also easier to fly than a turbocharged engine, since it never develops more power than would be developed at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All altitude engines also typically have a controllable-pitch prop, and develop more than 200 horsepower, so they would require both a &lt;a href=&quot;http://en.wikipedia.org/wiki/Complex_airplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;complex aircraft endorsement&lt;/a&gt; and a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Advanced-Flight-Training/Transitioning-to-High-Performance-Aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;high-performance endorsement&lt;/a&gt;. See &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.31&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR Part 61.31&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2019-04-30T17:35:38.863" LastActivityDate="2019-04-30T17:35:38.863" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="11233" PostTypeId="2" ParentId="11225" CreationDate="2014-12-18T18:33:12.020" Score="5" Body="&lt;p&gt;One other consideration not yet mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft tyres are highly pressurised.  An exploding tyre will throw debris in unpredictable directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a brake or other undercarriage fire, the firefighters are trained to approach the fire from the front or behind since the fusible plugs are designed to rupture and vent the pressure &lt;strong&gt;sideways&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, a fire in the wheels weakens the alloy.  If the tyre explodes, then sometimes the wheel explodes too and hot pieces of metal zooming around are even worse than the rubber.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2014-12-18T21:59:27.067" LastActivityDate="2014-12-18T21:59:27.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11234" PostTypeId="2" ParentId="11219" CreationDate="2014-12-18T19:06:25.363" Score="7" Body="&lt;p&gt;It would theoretically be possible for sloshing fuel to shift the center of gravity (CG) enough to cause an uncontrollable pitch up, leading to a stall. Designers know this and use various methods to prevent fuel from shifting too much when maneuvering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, the fuel is generally stored close to the CG (at least longitudinally, which is in pitch), mostly in the wings and sometimes in the fuselage between the wings. This is to prevent large changes in the CG as fuel is consumed during the flight. So while fuel certainly is heavy, movement will be close to the CG and affect balance less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/11224/1696&quot;&gt;Peter Kämpf notes&lt;/a&gt;, roll conditions are important as well, and of course having fuel out in the wings will affect latitudinal stability (but also longitudinal with increasing wing sweep). One way to control this is through the use of baffles (or subdivisions). These limit the amount of area available for the liquid to move between areas, preventing large changes during maneuvers but allowing enough fuel to flow during regular fuel burn, refueling, or tank tranfers. Baffles have the added benefit of providing more structural strength, which is particularly important in aircraft. Wing ribs act as baffles in the wings.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-12-18T19:06:25.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11235" PostTypeId="1" AcceptedAnswerId="11238" CreationDate="2014-12-18T21:18:12.753" Score="7" ViewCount="1908" Body="&lt;p&gt;While &lt;a href=&quot;https://aviation.stackexchange.com/a/11153/65&quot;&gt;answering&lt;/a&gt; this question (&lt;a href=&quot;https://aviation.stackexchange.com/q/572/65&quot;&gt;How can reducing power too quickly on a piston engine damage it?&lt;/a&gt;), &lt;a href=&quot;https://aviation.stackexchange.com/users/4508/barit1&quot;&gt;barit1&lt;/a&gt; said that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Skydiving planes see a LOT of shock cooling, and they pay for it at overhaul time&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What exactly happens during a skydiving flight which causes a lot of shock cooling?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2017-04-30T21:44:33.737" Title="How does skydiving flight cause shock cooling?" Tags="&lt;aircraft-maintenance&gt;&lt;piston-engine&gt;&lt;skydiving&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11236" PostTypeId="2" ParentId="11235" CreationDate="2014-12-18T21:51:15.470" Score="7" Body="&lt;p&gt;Because they tend to climb quickly to get to jump altitude (high power, hot engine) then descend very quickly to pick up the next batch of sky divers.  Time = money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close the throttle, point the nose at the landing site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However &lt;a href=&quot;https://aviation.stackexchange.com/users/1632/paul&quot;&gt;paul&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/572/how-can-reducing-power-too-quickly-on-a-piston-engine-damage-it#comment20824_11153&quot;&gt;indicates in the comments&lt;/a&gt; that he worked at a centre where they took this into account and exercised caution (good airmanship) in how the engine was treated.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-12-18T22:13:44.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11237" PostTypeId="1" AcceptedAnswerId="11239" CreationDate="2014-12-18T21:53:20.767" Score="26" ViewCount="3197" Body="&lt;p&gt;Pilots have to be able to handle a wide range of emergencies in the air. For powered aircraft, the obvious example to me is recovering from an engine failure, but obviously this can't happen on an unpowered glider. Many gliders have no electrical systems, so an electrical failure can't happen. A stall, I believe, can, and I assume the recovery would be similar to in a powered aircraft. What other emergencies should a glider pilot be able to handle? I'm especially interested in any emergencies that powered aircraft don't have to deal with.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="572" LastEditDate="2015-02-19T08:44:43.013" LastActivityDate="2019-08-05T12:13:14.743" Title="What emergency situation can pilots encounter in gliders/non-powered aircraft?" Tags="&lt;emergency&gt;&lt;glider&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11238" PostTypeId="2" ParentId="11235" CreationDate="2014-12-18T21:55:28.700" Score="10" Body="&lt;p&gt;Skydiving flights are abusive on engines for a number of reasons, but it's all tied to the fact that these flights are all about getting up to altitude, kicking the jumpers out, and &lt;a href=&quot;https://www.youtube.com/watch?v=VPGSzLhCKlc&quot;&gt;putting the plane back on the ground as fast as possible&lt;/a&gt; so you can pick up the next group and do it all again, as many times as possible in a day.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;While all skydiving descents aren't as dramatic as the video I linked to its not uncommon for skydiving pilots to make a very rapid descent at or near idle power. This causes a more drastic temperature change in the engine (particularly the cylinders, which are not producing as much heat but still have lots of air blowing through the fins).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the potential damage from rapid temperature changes the engine is also spending relatively little time at cruise power (it's either at full throttle climbing or near idle descending), and depending on the operation may be shut down between jumps. This is far from the ideal situation where the engine would run at 60-75% power as long as possible. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-18T21:55:28.700" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11239" PostTypeId="2" ParentId="11237" CreationDate="2014-12-18T22:04:01.167" Score="33" Body="&lt;p&gt;The number one emergency in a glider is a tow rope break at low altitude, less than 200 feet above the ground with no appreciable headwind. Below 200 feet, the proper technique is to land straight ahead, which usually means landing off airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between 200ft and 500ft, it is possible to make a U-turn back to the runway, and land in the opposite direction in which you took off.  The main hazard with this kind of landing is landing with a tailwind, and once the wheel touches the ground, the flight controls operate in the reverse direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above 500 feet, it is possible to fly an abbreviated pattern and land on the runway you took off from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add 50 feet of altitude for each 10 knots of headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some other tow emergencies are inability to release to tow rope, in which case the tow pilot needs to release the rope on his end; engine failure of the tow-plane; and a double tow rope release failure, which means the glider needs physically break the tow rope (it has a pre-determined breaking strength of 80-200% of the weight of the glider) or to land behind the tow-plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also run out of altitude and have to land in a field, which is called an &quot;off airport landing.&quot; Someone has to come and get you with a trailer, and you disassemble the glider and drive it away. One hazard is the off airport landing in a field, and the farmer comes out with his shotgun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other hazards are flying into the clouds or into severe turbulence, which can happen when the glider pilot is flying &quot;wave,&quot; a kind of lift generated by strong winds in proximity to&#xA; mountains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When thermaling, you are flying very tight steep turns, often with other sailplanes who are also trying to gain altitude. Everyone is supposed to fly the thermal in the same direction, and there is the hazard of colliding with other gliders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/glider_handbook/media/gfh_ch08.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Glider Flying Handbook - Abnormal and Emergency Procedures&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="13197" LastEditDate="2016-06-29T10:35:51.513" LastActivityDate="2016-06-29T10:35:51.513" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="11240" PostTypeId="2" ParentId="10025" CreationDate="2014-12-18T22:11:12.133" Score="7" Body="&lt;p&gt;The cargo hold will probably be quieter if the cabin is quieter, but there are multiple variables that can affect this. As Peter Kämpf commented, the noise source will depend on the position in the airplane. The two main sources of noise are the air moving past the airplane, and the engines. The two main noise concerns of manufacturers and operators are cabin noise and community noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing the noise at the source is one option. Engines are the main sources of noise and receive special treatment to reduce noise as much as possible. This can reduce cabin noise and/or community noise, and should help both the passenger and cargo decks. Newer aircraft like the A380 will tend to have quieter engine installations than older aircraft like the 747-400.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the cabin, noise can also be controlled with insulation. Insulation in the cabin will help with both noise and temperature control. Both are less important in the cargo hold, but do have some importance since it is only separated from the passenger area by the floor. Cargo hold insulation will provide protection for structure from fire or accidental damage, and some degree of temperature protection. So it is possible that the cabin receives added protection from these features that the cargo area does not benefit from.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2014-12-18T22:11:12.133" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11241" PostTypeId="2" ParentId="11235" CreationDate="2014-12-18T23:53:16.360" Score="4" Body="&lt;p&gt;The aircraft in the referenced video showing a very rapid descent is a King Air (or similar). Turbine aircraft really don't have shock cooling issues - standard procedure is engines to flight idle, props to flat pitch, nose down to Vne. Planes like a Pilatus Porter can descend faster than freefalling jumpers and are often used as extras in films (you need to plan these shots with the pilot).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Shock cooling&quot; by definition is a temperature change faster than the metal can react, leaving you with a cylinder that is hot on one side and cool on the other. As I mentioned elsewhere, this is caused mainly by bad airmanship. My place covered this quite well in training, and we didn't have too many problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(pop quiz moved to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11243/pop-quiz-for-commercial-pilots-and-cfis&quot;&gt;separate question&lt;/a&gt; )&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-12-19T01:10:23.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11242" PostTypeId="2" ParentId="11237" CreationDate="2014-12-19T00:24:24.937" Score="7" Body="&lt;p&gt;In addition to the emergencies mentioned by rbp, there's also spin recovery.   Presumably power pilots need to know this as well, but it is more relevant to glider pilots because thermalling can take you close to the incipient spin territory.   In Australia, at least, real spin recovery is practiced until the pilot is proficient at recovery.&lt;/p&gt;&#xA;" OwnerUserId="945" LastActivityDate="2014-12-19T00:24:24.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11245" PostTypeId="2" ParentId="11235" CreationDate="2014-12-19T02:08:41.623" Score="2" Body="&lt;p&gt;Shock cooling is not a problem in reciprocating aircraft engines.  In fact, today you almost only hear it mentioned in the context of turbocharged aircraft, and even then to avoid shock cooling of the turbocharger.  Another common misconception.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll find no mention of shock cooling in the Pilot's Operating Handbook.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/pelican/182107-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;http://www.avweb.com/news/pelican/182107-1.html?redirected=1&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="5573" LastEditorUserId="6886" LastEditDate="2016-02-24T19:42:12.787" LastActivityDate="2016-02-24T19:42:12.787" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11246" PostTypeId="1" AcceptedAnswerId="11248" CreationDate="2014-12-19T02:33:58.157" Score="10" ViewCount="5081" Body="&lt;p&gt;I've always used PARE for spin recovery:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;b&gt;P&lt;/b&gt;ower to idle&lt;br&gt;&#xA;  &lt;b&gt;A&lt;/b&gt;ilerons neutral&lt;br&gt;&#xA;  &lt;b&gt;R&lt;/b&gt;udder opposite the spin until rotation stops&lt;br&gt;&#xA;  &lt;b&gt;E&lt;/b&gt;levator forward to break the stall &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is Beggs/Mueller emergency spin recovery, and why does it work?&lt;br&gt;&#xA;Does it work in any aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-19T03:14:01.260" LastActivityDate="2015-08-14T01:26:10.837" Title="What is the Beggs/Mueller emergency spin recovery technique?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;spins&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11247" PostTypeId="2" ParentId="2170" CreationDate="2014-12-19T02:44:40.580" Score="9" Body="&lt;p&gt;I have recovered from a flat spin doing upset training in a Extra300L. &lt;a href=&quot;https://www.youtube.com/watch?v=6NEpoUET_wo&quot; rel=&quot;noreferrer&quot;&gt;Here's the video&lt;/a&gt; (you'll notice a secondary stall at 0:33 because I pulled too hard in the dive).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's interesting to note how one enters such a spin: first you enter a regular spin, and let it develop fully, then you do everything wrong: add full power, pull back on the sick, and depress the &quot;soft&quot; rudder in the direction of the spin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens is very interesting: the spin starts to accelerate as the point of rotation moves from somewhere in front of the nose, backwards until it's inside the plane and the nose is moving one way (EG port) and the tail moving the other (starboard). It rotates a few times per second. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recovery was fairly standard in the Extra300L: just PARE, and you're out in a second (that feels like an hour)&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-19T03:12:22.120" LastActivityDate="2014-12-19T03:12:22.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11248" PostTypeId="2" ParentId="11246" CreationDate="2014-12-19T03:09:29.707" Score="9" Body="&lt;p&gt;From &lt;a href=&quot;http://spirit.eaa.org/intheloop/articles/1006_spin_recovery.asp&quot;&gt;the fine folks over at EAA&lt;/a&gt;, the Beggs/Mueller technique (also sometimes called the &quot;hands-off&quot; spin recovery technique) is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Power – Off. &lt;em&gt;(presumably they mean &quot;to idle&quot;, and not &quot;stop the engine&quot;)&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;Remove your hand from the stick.&lt;/li&gt;&#xA;&lt;li&gt;Apply full opposite rudder until rotation stops.&lt;/li&gt;&#xA;&lt;li&gt;Neutralize rudder and recover to level flight.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So essentially the same technique as PARE, except instead of neutralizing the ailerons &amp;amp; pushing the nose over you put your hands in your lap:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;b&gt;P&lt;/b&gt;ower: to idle&lt;br&gt;&#xA;  &lt;b&gt;A&lt;/b&gt;ilerons: Put your hands in your lap.&lt;br&gt;&#xA;  &lt;b&gt;R&lt;/b&gt;udder: Full opposite the direction of spin until rotation stops.&lt;br&gt;&#xA;  &lt;b&gt;E&lt;/b&gt;levator: &lt;em&gt;Your hands should still be in your lap!&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The big advantage to the Beggs/Mueller technique seems to be that with your hands off the stick there's no chance of the pilot panicking and yanking back on the stick/yoke and prolonging the spin.  It's predicated on the fact that the nose will fall naturally in a stall, breaking the stall and putting the plane into a slight dive.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I can't say as to whether the Beggs/Mueller technique will work in &lt;em&gt;all&lt;/em&gt; aircraft, but it should work in any plane that tends to naturally recover from a stall (i.e. one where the nose naturally falls when the plane is stalled) and has otherwise-conventional spin recovery characteristics. That covers every plane that immediately comes to mind, but it's possible there are some with a canard configuration where spin recovery isn't conventional, and the Beggs/Mueller technique may also not be ideal.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-12-19T03:31:40.907" LastActivityDate="2014-12-19T03:31:40.907" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11250" PostTypeId="1" CreationDate="2014-12-19T04:24:50.473" Score="2" ViewCount="59" Body="&lt;p&gt;What is the protocol if the ATC tower needs to be evacuated for some emergency, for example a fire? How can operations continue if there aren't any controllers?&lt;/p&gt;&#xA;" OwnerUserId="5576" LastActivityDate="2014-12-19T04:24:50.473" Title="Protocol for emergency evacuation of atc tower" Tags="&lt;airport&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2014-12-19T14:20:51.243" ContentLicense="CC BY-SA 3.0" />
  <row Id="11251" PostTypeId="1" AcceptedAnswerId="11252" CreationDate="2014-12-19T04:25:31.687" Score="16" ViewCount="2743" Body="&lt;p&gt;I just saw a photo of &lt;a href=&quot;http://pipistrel-usa.com/models/apis.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Pipistrel Apis&lt;/a&gt; motor-glider, and it got me wondering: How can it safely land with only 2 wheels total? To me it seems that falling to the side would be inevitable, and with wing fuel tanks, that could be terrible. In all the pictures, it's resting on (one of the) wingtips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/l9WUL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the wings/wingtips reinforced for landing &amp;amp; supporting the airplane on the ground?&lt;/p&gt;&#xA;" OwnerUserId="2353" LastEditorUserId="2171" LastEditDate="2014-12-24T14:13:41.117" LastActivityDate="2014-12-24T14:13:41.117" Title="How can the Pipistrel Apis land safely?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;landing&gt;&lt;landing-gear&gt;&lt;glider&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11252" PostTypeId="2" ParentId="11251" CreationDate="2014-12-19T04:41:43.003" Score="24" Body="&lt;p&gt;Many modern gliders only have &lt;em&gt;one&lt;/em&gt; wheel -- two is a great luxury!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a glider the wing and flight controls remain effective until the aircraft is almost completely stopped - with a little training and practice it's possible to balance on the one (or two) wheels right up to the point where you're nearly stopped, at which point the glider will gently tip onto one of its wings as it comes to a halt.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you've surmised the wingtip usually has some reinforcement or other provision (such as a skid plate or a small wheel) to prevent damage when it contacts the ground. The photo below is of one of these wingtip wheels.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/m02Eo.jpg&quot; alt=&quot;304S sailplane wing-wheel&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-19T04:41:43.003" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11256" PostTypeId="2" ParentId="11246" CreationDate="2014-12-19T07:42:33.383" Score="10" Body="&lt;p&gt;The Beggs/Mueller technique is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;engine idle&lt;/li&gt;&#xA;&lt;li&gt;let go of the stick&lt;/li&gt;&#xA;&lt;li&gt;push rudder against spin direction&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This was developed for pilots of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pitts_Special&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pitts Special&lt;/a&gt; biplane and will work well with naturally stable, powered aircraft. With gliders (where it strictly doesn't apply) it will be less effective, but still work in most cases. The better way is to combine both, rudder against the spin and stick forward (your PARE technique), but only until the rotation stops. Then both the stick and the rudder must be neutral until speed is sufficient for the pull-out. Beggs/Mueller is more about avoiding wrong inputs due to confusion than ending the spin in the most direct way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spin recovery with the hands off the stick will be slower than with active control input. If the control surfaces are free-floating, natural stability is normally less than what it is with fixed control surfaces. For that reason, the Beggs/Mueller technique is less effective than actively ending the spin with both rudder and elevator. If the pilot does not realize he is in an inverted spin, pushing down will make matters worse, however.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why rudder against spin direction?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An aircraft spins &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin/8590#8590&quot;&gt;because something stabilizes both the rotation and the high pitch angle&lt;/a&gt;. First the rotation: This is caused by fully separated airflow on the retreating wing while some section on the advancing wing has attached airflow. The high drag on the retreating wing pulls this side of the aircraft backwards, while the lift on the section of wing with attached airflow pulls that side of the aircraft forward. Remember, airflow is mostly coming from below, and the spin motion modifies the local flow direction the more one moves away from the center of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why elevator forward (Back in inverted spin)?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now the pitch angle: The center of rotation is ahead of the wing in the forward fuselage. The masses in the forward fuselage produce little centrifugal force, while the masses in the rear fuselage and the tail, having a substantial distance from the center of rotation, produce a substantial centrifugal force which pulls the whole aircraft into a level attitude. Since the aircraft's motion is mainly downward, this inertial moment increases the angle of attack above the stall angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To break the spin one needs to end the rotation &lt;strong&gt;or&lt;/strong&gt; the pitch attitude. Since they mutually reinforce each other, one must be ended to end both. On aircraft with long fuselages the rudder is more effective to stop the rotation, while on aircraft with long wings the elevator will be more effective in ending the spin via reducing pitch attitude. The rotation is then stopped by the roll damping of the wing. Using both together will give the best effect, however.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why engine to idle?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Having some added dynamic pressure on the vertical tail will also help to end the rotation, but then the aircraft will pick up speed very quickly. Setting the engine to idle will avoid falling into this particular trap, but again for the price of a somewhat slower recovery. Sometimes an aircraft needs that added dynamic pressure to end the rotation, so Beggs/Mueller will not work in all cases.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-12-19T13:22:13.140" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11257" PostTypeId="2" ParentId="11251" CreationDate="2014-12-19T11:33:59.757" Score="8" Body="&lt;p&gt;Almost every glider has just one wheel close to the centre of mass. Some have a small tail wheel, school gliders may have a front wheel that avoids to scratch the nose when you are learning. Whatever the number of wheels is, you spend most if not all the time balancing on the main one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every skilled glider pilot is against anything that could create even the minimum amount of drag and is not strictly necessary!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key point here is the amount of fuel inside the wings, which is really tiny (a small motorbike tank per wing) and allows for safe landings. If it was more it could create problems mostly because of its weight and the related stress on the wings when touching down. Indeed most of the competition gliders allow to fill their wings with water in order to increase the performances at high speeds, however it is mandatory to evacuate it before touching down, and of course you wouldn't want to do the same with unspent fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0bbRg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2345" LastEditorUserId="2345" LastEditDate="2014-12-24T09:45:44.390" LastActivityDate="2014-12-24T09:45:44.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11258" PostTypeId="1" CreationDate="2014-12-19T14:22:50.817" Score="1" ViewCount="2844" Body="&lt;p&gt;Autogyros seem to be one of those mythical creatures: we know there are actually a few of them out there and they're supposed to be fun to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they really; how do they work? And how do you fly one?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="19" LastEditDate="2016-07-05T11:12:33.890" LastActivityDate="2016-07-05T11:12:33.890" Title="What is an autogyro, and why would I ever want to fly one?" Tags="&lt;autogyro&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ClosedDate="2014-12-20T10:25:18.010" ContentLicense="CC BY-SA 3.0" />
  <row Id="11259" PostTypeId="2" ParentId="11258" CreationDate="2014-12-19T15:12:51.650" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is an autogyro?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Autogyros have been around for decades. They are also known as gyrocopters, gyroplanes, and autogiros. Gyroplane is the official FAA designation. It is basically a rotary wing aircraft just like a helicopter because the rotor  provides lift instead of wings like conventional airplanes.Since the rotor is not powered, an Autogyro uses a separate source for propulsion, just like an airplane. In other words, an Autogyro uses a propeller for forward motion and a freely rotating, un motorized rotor for lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.jefflewis.net/autogyros.html&quot; rel=&quot;nofollow&quot;&gt;http://www.jefflewis.net/autogyros.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How do you fly one?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are only three flight &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/rotary/autofly.htm&quot; rel=&quot;nofollow&quot;&gt;controls&lt;/a&gt;: a control stick, rudder pedals and a throttle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autogyros do not stall, so it is a lot safer to fly an Autogyro than say a helicopter.You can expect control responses to be faster in a Autogyro than an airplane because you are moving the whole wing  instead of just a  tiny control element attached to a wing. Generally speaking, the control response will not be as quick as a helicopter because of the lower operating rpm of the Autogyro’s rotor system.The critical task in flying a Autogyro is managing the energy of the rotor. If you fail to maintain air flowing through it, the speed drops drastically, and so does the rotor's ability to provide lift.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-12-19T15:12:51.650" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11260" PostTypeId="1" AcceptedAnswerId="11261" CreationDate="2014-12-19T16:32:48.513" Score="11" ViewCount="13934" Body="&lt;p&gt;In a hobby drone, is it possible to set up the autopilot so that the drone travels to a distance far beyond the range of the remote control device and then comes back to the starting point? When I see hobbyists flying drones , it seems the drone always hovers within the boundaries of the field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible for a drone to reach a friend's house on the other side of town and then come back to the start point?&lt;/p&gt;&#xA;" OwnerUserId="5556" LastEditorUserId="97" LastEditDate="2014-12-20T00:39:29.443" LastActivityDate="2016-05-16T08:24:22.237" Title="Can a drone travel beyond the range of its remote control signal?" Tags="&lt;autopilot&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11261" PostTypeId="2" ParentId="11260" CreationDate="2014-12-19T17:00:24.930" Score="14" Body="&lt;p&gt;If the controlling software allows it then yes. There's at least one drone available where autonomous flight &lt;a href=&quot;https://www.youtube.com/watch?v=qajTB3g8TrU&quot;&gt;is possible&lt;/a&gt;; the &lt;a href=&quot;http://www.dji.com/product/phantom-2-vision/faq&quot;&gt;Vision 2 FAQ&lt;/a&gt; says that the drone will continue its &quot;mission&quot; even if you lose the signal to it, although the overall length of the flight path is limited to 5km and the drone will not fly close to airports. Other drones stop and hover or land if they lose the connection to the controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether doing this is actually a good idea (or legal in whichever jurisdiction you want to operate in) or not is a whole other question.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-19T17:24:10.327" LastActivityDate="2014-12-19T17:24:10.327" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11262" PostTypeId="1" AcceptedAnswerId="11263" CreationDate="2014-12-19T19:37:45.867" Score="17" ViewCount="1587" Body="&lt;p&gt;I was under the impression that things like this:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3uyta.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and soon this&#xA;&lt;img src=&quot;https://i.stack.imgur.com/pOCz8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and even this&#xA;&lt;img src=&quot;https://i.stack.imgur.com/gsWO4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are drones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When and how did the media and the general public get the idea that these:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/vc3nK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are also drones?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not going to argue with the fact that the label has been given.  But remote controlled quad coppers are just another type of remote controlled aircraft, what makes them different from RC planes and RC helos?  (Nothing.)  So why are they being deliberately group with full sized military aircraft that are used for killing terrorist and patrolling dangerous regions?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, while RC quad copters have been labeled by the public and the media as &quot;drones&quot; are they really?  What makes &quot;a drone&quot; really a drone?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="62" LastEditDate="2014-12-19T19:52:19.977" LastActivityDate="2017-12-17T16:52:28.017" Title="What exactly is a &quot;drone&quot;?" Tags="&lt;terminology&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11263" PostTypeId="2" ParentId="11262" CreationDate="2014-12-19T20:19:08.623" Score="16" Body="&lt;h2&gt;General usage&lt;/h2&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.etymonline.com/index.php?term=drone&quot; rel=&quot;noreferrer&quot;&gt;Etymology Online&lt;/a&gt; The term drone, meaning &amp;quot;pilotless aircraft&amp;quot; dates from 1946.&lt;/p&gt;&#xA;&lt;p&gt;It evidently encompasses all types of aircraft where no onboard human pilot is needed, either because the human pilot operates the aircraft remotely (still true for most types of military &amp;quot;drone&amp;quot; aircraft I believe) or because the aircraft systems are capable of full autonomy during some of all of a flight.&lt;/p&gt;&#xA;&lt;p&gt;The earliest uses were probably &amp;quot;target drones&amp;quot;. Which is what &lt;a href=&quot;http://en.wikipedia.org/wiki/Target_drone&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; suggests.&lt;/p&gt;&#xA;&lt;p&gt;The term does seem to have supplanted &amp;quot;RC aircraft&amp;quot; for modern small RC aircraft, especially those which carry a camera and/or from which their operators derive some value other than simply from mastering the skill of flying the vehicle.&lt;/p&gt;&#xA;&lt;p&gt;English language is defined by usage, not by edict. So this isn't subject to rulings or appeal.&lt;/p&gt;&#xA;&lt;p&gt;Lawmakers or other bodies might define the term more narrowly but this doesn't affect other uses of the same word.&lt;/p&gt;&#xA;&lt;h2&gt;FAA definition&lt;/h2&gt;&#xA;&lt;p&gt;The FAA talks mainly about &amp;quot;model aircraft&amp;quot; and &amp;quot;unmanned model aircraft&amp;quot; (&lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=16474&amp;amp;cid=TW223&quot; rel=&quot;noreferrer&quot;&gt;ref.&lt;/a&gt;) and about Unmanned Aircraft(UA)  or Unmanned Aerial Systems (UAS). (&lt;a href=&quot;https://www.faa.gov/uas/faq/#qn3&quot; rel=&quot;noreferrer&quot;&gt;ref.&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;They usually don't use the term drone or &lt;a href=&quot;https://www.faa.gov/uas/regulations_policies/&quot; rel=&quot;noreferrer&quot;&gt;define&lt;/a&gt; it, but from their &lt;a href=&quot;http://www.faa.gov/news/updates/?newsId=76381&quot; rel=&quot;noreferrer&quot;&gt;FAQ&lt;/a&gt; it seems they consider the terms drone and UAS to be equivalent&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Myth #7:The FAA is lagging behind other countries in approving commercial drones.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Fact– This comparison is flawed.  The United States has the busiest, most complex airspace in the world, including many general aviation aircraft that we must consider when planning UAS integration, because those same airplanes and small UAS may occupy the same airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2014-12-19T20:38:15.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11264" PostTypeId="2" ParentId="11262" CreationDate="2014-12-19T22:05:47.417" Score="5" Body="&lt;p&gt;&quot;Drone&quot; is a very general expression for a wide range of vehicles, and it is mostly used by the press and outsiders. Lately, the word has been picked up by Marketing to give model aircraft a more fancy label. People who design and use unmanned aircraft tend to use more specific expressions.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Will it return?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The earliest use of unmanned vehicles was for one-way missions, either as &lt;a href=&quot;http://en.wikipedia.org/wiki/Target_drone&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying targets&lt;/a&gt; or as &lt;a href=&quot;http://en.wikipedia.org/wiki/V-1_flying_bomb&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying bombs&lt;/a&gt;. While the flying bombs are today mostly called cruise missiles, the term &quot;drone&quot; initially was reserved for the unarmed variety, serving as targets. Note that technical limits would not allow the early models to make a controlled landing. They were one-way vehicles. Only later, with better radio control, could target drones be reused.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Will it fly autonomously?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;With the immense increase in computing power, the pilot did not have to be in the loop all the time, and unmanned vehicles learned to land to be reused. The term &quot;drone&quot; never was used by those who designed and built them in order to make a distinction between their sophisticated unmanned vehicles and those dumb, one-way drones. The whole combination of ground station, data relay and flying vehicle became an unmanned system to stress the multi-component nature of these things. The vehicle itself is now called a UAV for unmanned aerial vehicle, or UCAV in case of armed unmanned combat aerial vehicles. Other functions gave rise to names like HALE (high altitude, long endurance) which doesn't even mention the unmanned nature of these craft. But they never are called drones by their makers.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Does it carry ordnance?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If you answer all three questions &quot;No&quot;, it is a drone. Strictly speaking, if one question has a positive answer, there is a better term for it. Note that the first question also excludes model aircraft but also more modern target drones! Taking the examples in your question, only the third picture shows a drone (if it will be shot at later and there is a distinct likelihood that it doesn't land in one piece).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Use of the term by the general public&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the more specific terms have never left the ghetto of specialist technical terminology, and the press has decided to call all unmanned aircraft &quot;drones&quot;. It is similar to the word &quot;hacker&quot; which originally described computer experts and now is used for criminals by the public.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-12-17T16:52:28.017" LastActivityDate="2017-12-17T16:52:28.017" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11265" PostTypeId="1" AcceptedAnswerId="11288" CreationDate="2014-12-20T00:02:42.300" Score="20" ViewCount="1365" Body="&lt;p&gt;I was on approach to Vienna yesterday evening when I observed two 2-second green laser flashes 5 seconds apart from one of the rear passenger windows of the B737 where I was seated being pointed at the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering if and what I should do since green lasers are dangerous, and I'm convinced the aircraft was being targeted. Should I report this to the relevant authorities? Is it very common or a rare occurrence? The co-pilot didn't seem very bothered about it in any case and he hadn't seen it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Updates:&lt;br&gt;&#xA;20th December 2014: Sent an email to the relevant Austrian authorities. Will see if I get a reply.&lt;br&gt;&#xA;22nd December 2014: Sent a report to AustroControl as well.&lt;br&gt;&#xA;8th June 2015: No reply to date.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-08T11:25:50.363" LastActivityDate="2015-06-08T11:25:50.363" Title="Is it worth reporting that I saw a green laser being pointed at the aircraft as a passenger?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;passenger&gt;&lt;laser-illumination&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11266" PostTypeId="1" AcceptedAnswerId="11269" CreationDate="2014-12-20T02:43:47.127" Score="17" ViewCount="18843" Body="&lt;p&gt;The incredibly bad, postapocalyptic tv series &lt;a href=&quot;http://en.wikipedia.org/wiki/Revolution_%28TV_series%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Revolution&lt;/a&gt; begins with a mysterious event that causes all electrical systems to fail all over the globe.  Even batteries don't work anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first episode, after the &quot;event&quot; airplanes immediately start falling out of the sky in flat spins. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This had me thinking: which airplanes could survive an EMP-type event (FN1) that fries all electronics and renders electrical systems unusable?  This means that even RATs would not be a viable choice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Piper cubs and other single-engine planes with purely mechanical linkages could still keep on gliding and land safely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think any large airliner currently flying could make it. Could even a B-17 or DC-10 make it with no powered electrical systems -- just on unpowered hydraulics alone?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: if they did fall out of the sky, I'm assuming it would be in lawn dart mode and not in flat spins?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Footnote 1: While the apocalypse event in Revolution turns out to not be an EMP, you can assume it was something similar for the purpose of this question.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2017-12-17T23:23:20.217" LastActivityDate="2018-07-20T20:19:24.990" Title="Which airliners could survive an EMP pulse?" Tags="&lt;hypotheticals&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11267" PostTypeId="2" ParentId="11260" CreationDate="2014-12-20T02:46:22.633" Score="4" Body="&lt;p&gt;Yes, most of the sophisticated consumer drones allow you to pre-program a track into them and can fly totally autonomously. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, most of even the less expensive drones (FN1) are designed to return back to their starting GPS coordinates if they lose their control signal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fn1: Less expensive still means around USD 500 or so. Sophisticated drones are USD 1000 and up.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-01-27T14:49:47.860" LastActivityDate="2015-01-27T14:49:47.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11268" PostTypeId="2" ParentId="11262" CreationDate="2014-12-20T03:23:23.400" Score="2" Body="&lt;p&gt;An actual drone is a male honeybee which makes no honey and has no sting. The word is likely an imitatation of the sound they make when swarming. Calling military target aircraft drones was probably originally a humourous analogy. They carry no cargo, have no armaments, and like the drone which dies after its midair mating they do their job only once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this perspective calling an armed aircraft such as the Predator a drone does not make much sense. It performs work, most definitely has a sting, and flies many times. But the term was already familiar in the military and so its meaning got extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the meaning has recently been extended without much thought going into it, there is no broad agreement on what it means. Some would like to see the term used only for aircraft which display drone-like behavior. Others are willing to apply it to most any aircraft without a human pilot on board.&lt;/p&gt;&#xA;" OwnerUserId="5585" LastEditorUserId="5585" LastEditDate="2014-12-21T05:25:51.393" LastActivityDate="2014-12-21T05:25:51.393" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11269" PostTypeId="2" ParentId="11266" CreationDate="2014-12-20T03:34:46.993" Score="17" Body="&lt;p&gt;Older airliners use hydraulics and cables attached to the pilot controls. Some RATs power the hydraulics directly as well so limited control is still possible then. The pilots would get a workout but the plane would safely touch down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However planes with entirely fly-by-wire systems (no current airliner is completely fly-by-wire) will be completely uncontrollable apart from shifting weight and would glide to the ground. They are made stable so they won't just enter a spin and pancake into the ground.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-07-17T14:13:14.813" LastActivityDate="2015-07-17T14:13:14.813" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11270" PostTypeId="2" ParentId="11266" CreationDate="2014-12-20T05:09:53.917" Score="12" Body="&lt;p&gt;Well the key to an airliner (or any other vehicle) surviving a &lt;em&gt;real&lt;/em&gt; EMP would be having engines and flight control systems that don't require any kind of computer assistance. Hydraulic control systems powered directly by the engine and not relying on a computer to operate the valves would continue to function, as would cable-driven control systems. Simple electric motors may also continue to operate (larger motors tend to be EMP-resistant, in smaller motors there's a chance the EMP could burn out the windings or arc over and destroy the brushes) which means we can assume you'd still be able to pump fuel into the engines of most jet airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thinking along those lines I imagine the remaining &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-3&quot;&gt;DC-3 fleet&lt;/a&gt; would be almost entirely unfazed by an EMP (save for any retrofitted avionics, radios, etc. which would likely be fried). Similarly the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_707&quot;&gt;Boeing 707&lt;/a&gt; would probably not have a problem, nor would early-generation DC-9s, 727s, and 747s - you would lose any retrofitted flight management computers, but they are generally not essential to operation in the earlier-generation aircraft.&lt;br&gt;&#xA;There are probably several other models still in service (or hanging around various boneyards) which are at least somewhat EMP-resistent.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If we assume a Revolution-style apocalypse where &lt;strong&gt;&lt;em&gt;absolutely nothing using electricity&lt;/em&gt;&lt;/strong&gt; works you're rather worse off: only aircraft which have cable-driven controls (or hydraulic backups with manual valve actuation &amp;amp; direct pressurization from the ram air turbine) would have functional flight controls. Thats a much smaller subset of the fleet these days, but the planes do exist - as Terry pointed out the 727 and 747 both have non-electric control systems available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume magnetos can still generate a spark the DC-3 other planes of its generation would be the clear winner: The engines would continue to run until stopped (the engine-driven fuel pumps would continue to feed the engine fuel). Aircraft like this could even possibly be restarted (using shotgun starters or pull starters, and a little help getting fuel to the engine until the mechanical fuel pump could take up the job).&lt;br&gt;&#xA;If we assume magnetos would also stop working then at least you'd have flight controls and the ability to make a controlled emergency landing &lt;em&gt;somewhere&lt;/em&gt; as you could in the other planes mentioned.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-20T05:09:53.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11271" PostTypeId="1" AcceptedAnswerId="11280" CreationDate="2014-12-20T05:41:02.890" Score="12" ViewCount="8099" Body="&lt;p&gt;When flying into a towered airport in VFR, is the pilot expected to enter a standard traffic pattern, or should the plane be flown in the most direct route to final as practical?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if westbound into a class D airport with a north-south runway landing on runway 18, should the pilot enter the pattern at a 45 midfield, fly parallel on downwind as usual, then start the descent normally when abeam the threshold, turning left base and final? Or should the pilot simply fly to the north of the field and start the descent and turn a left final approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AIM 4-3-13 doesn't really explain towered airport operations, as far as how to enter the pattern. This is the most relevant explanation I can find:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When necessary, the tower controller will issue clearances or other&#xA;  information for aircraft to generally follow the desired flight path&#xA;  (traffic patterns) when flying in Class B, Class C, and Class D&#xA;  surface areas and the proper taxi routes when operating on the ground.&#xA;  If not otherwise authorized or directed by the tower, pilots of&#xA;  fixed-wing aircraft approaching to land must circle the airport to the&#xA;  left. However, in all instances, an appropriate clearance must be&#xA;  received from the tower before landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've only flown into a few class D airports (only 3 months since I got my license), and wasn't sure about how to approach the field in certain situations. Some were straight in approaches, but a couple were generally as I described above. The tower usually says to report at 3 miles, or when turning to final. &quot;When necessary&quot; ATC will issue clearances for traffic patterns, but what to do if they just tell you are clear to land? Does &quot;circle the airport to the left&quot; mean do the full pattern procedure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During flight training I never experienced anything other than pretty much a straight in approach to class D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I found this explanation on a &lt;a href=&quot;http://www.willametteair.com/toweredairports.php&quot;&gt;flight instruction website&lt;/a&gt;: &quot;Pilots do not fly a standard traffic pattern at a towered airport, with a 45-degree entry to the downwind leg. Instead, aircraft enter the airport vicinity as instructed by ATC, reporting arrival on an assigned pattern leg and then accepting further instructions or a clearance to land.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to contradict the AIM explanation. And again, what if ATC doesn't instruct anything, what are they expecting the pilot to do? A standard pattern or a straight in approach as direct as possible?&lt;/p&gt;&#xA;" OwnerUserId="3670" LastEditorUserId="69" LastEditDate="2014-12-21T20:50:51.313" LastActivityDate="2014-12-22T23:42:55.403" Title="What is the correct traffic pattern at a towered airport?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;general-aviation&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11272" PostTypeId="1" AcceptedAnswerId="11274" CreationDate="2014-12-20T06:54:00.740" Score="6" ViewCount="4503" Body="&lt;p&gt;I understand that high speed turnoff is for the plane to exit the runway asap. What is its design specification and how fast can a plane use highspeed turnoff? Assuming only A320,737 and larger.&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2016-05-12T11:07:45.677" Title="What is the safe speed to use highspeed turnoff?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11273" PostTypeId="2" ParentId="11271" CreationDate="2014-12-20T07:00:27.923" Score="0" Body="&lt;p&gt;&lt;em&gt;(This is more from EASA regs, but FAA's should be identical)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying into class D airspace as VFR you are completely responsible for traffic separation. ATC will give you traffic information about other VFR and IFR flights, and traffic avoidance on request. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to be able to see other traffic and separate just as you would in uncontrolled airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tells me that , unless otherwise instructed  , I need to fly as usual and enter an appropriate traffic pattern to give me ( and others ) the chance to maintain visual separation. &lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2014-12-20T07:00:27.923" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11274" PostTypeId="2" ParentId="11272" CreationDate="2014-12-20T07:53:13.720" Score="8" Body="&lt;p&gt;Please be careful applying a blanket figure during high speed turnoff. There are many variables which you should consider. These are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;•   Exact angle of the taxiway(you're turning onto):  If it's a very shallow angle off the runway and therefore does not require much turning, high-speed turnoffs are easier and manageable, and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;•   Rate of deceleration&lt;/p&gt;&#xA;&#xA;&lt;p&gt;•   Side load limitations on the CRJ&lt;/p&gt;&#xA;&#xA;&lt;p&gt;•   Tolerance of the nose gear&lt;/p&gt;&#xA;&#xA;&lt;p&gt;•   Traffic situation on taxiway&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking you need both sets of eyes outside, especially if you are joining or crossing another Taxi Way.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2014-12-20T07:53:13.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11277" PostTypeId="1" AcceptedAnswerId="11279" CreationDate="2014-12-20T11:44:58.467" Score="7" ViewCount="9291" Body="&lt;p&gt;I experience barotitis only during SOME (not all) descents. During takeoffs, my ears feel different, but I feel no pain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the cause pilot's skills, rate of descent, or aviational? &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="128" LastEditDate="2019-10-20T06:23:54.923" LastActivityDate="2019-10-20T06:23:54.923" Title="Why barotitis, but only during descents and sometimes?" Tags="&lt;landing&gt;&lt;passenger&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="11278" PostTypeId="2" ParentId="11277" CreationDate="2014-12-20T13:24:51.203" Score="9" Body="&lt;p&gt;Ear discomfort during flight happens when the air pressure in the cabin changes faster than the air pressure in your &lt;a href=&quot;http://en.wikipedia.org/wiki/Tympanic_cavity&quot;&gt;tympanic cavity&lt;/a&gt; can follow it; the resulting pressure difference across the eardrum can hurt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the tympanic cavity &quot;remembers&quot; an earlier pressure, it can be &lt;em&gt;higher&lt;/em&gt; than ambient during departure, and &lt;em&gt;lower&lt;/em&gt; than ambient during descent. This creates different sensations; it seems to be common to find the descent situation more unpleasant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While rates of ascent and descent are not absolutely equal from flight to flight, the major variable is how fast the pressure in the tympanic cavity can be equalized through the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eustachian_tube&quot;&gt;eustachian tubes&lt;/a&gt;. This varies from person to person, as well as &lt;em&gt;from day to day&lt;/em&gt; for the same person.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The eustachian tube is usually closed but opens from time to time to allow the pressure in the ear to equalize. The tube often opens briefly as a side effect of jaw movement, swallowing and the like. If there's more mucus in your system than usual -- for example, if you have the beginnings of a cold that is otherwise too mild to annoy you -- effective openings of the tube can be less frequent (and the risk of discomfort during flight therefore higher).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if your state of health is 100% the same between two descents, random variations in how much you talk, chew, swallow saliva, and so forth, can make the difference between discomfort in one descent and none in another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Personally I've found that yawning is the most effective way for me to equalize pressure during descent, and swallowing which is otherwise widely recommended does little for me -- but not everybody works the same way).&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2014-12-20T13:24:51.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11279" PostTypeId="2" ParentId="11277" CreationDate="2014-12-20T14:05:19.973" Score="11" Body="&lt;p&gt;As a plane climbs out, the cabin pressure lowers so that it equals the same pressure as being at about 5,000 feet, the altitude of Denver. What happens inside your ear is that the pressure in the middle ear reduces to match the 5,000 foot cabin pressure, and you might sometime feel your ears &quot;pop,&quot; just like going up in an elevator in a tall building.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the plane descends, the pressure in your middle ear will still be at 5,000 feet, but the pressure in the cabin will go down to sea level (0 feet), and you will feel this pressure on your eardrum, which can cause a lot of discomfort until the pressure equalizes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure equalizes as air enters the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eustachian_tube&quot; rel=&quot;noreferrer&quot;&gt;eustachian&lt;/a&gt; tubes, which connect your middle ear to your nose and throat. The tube, however, is very narrow and can be blocked by inflammation or mucus due to a cold or other illness, and you won't be able to equalize the pressure. Flying with a cold can be very painful during descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of discomfort each passenger experiences is going to vary widely, even from flight-to-flight. For example, if the cabin altitude is 5,000ft and the destination is Denver, then the cabin will not have to further pressurize.  Some other factors are individual physiology (some people will have bigger eustachian tubes than others), illness, ethnicity/gender/gift-of-gab (some are more prone to talking than others, and talking can relieve the pressure), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, there are two things you can do: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;buy a plane with a lower cabin altitude. I recommend the Gulfstream 650, which has a cabin pressure of 2,765ft at an altitude of 41,000MSL&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;reduce the rates of your descents, which will give your ears a chance to equalize. ATC, however, &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0404.html&quot; rel=&quot;noreferrer&quot;&gt;expects you to descend at between 500 and 1,500FPM&lt;/a&gt;, unless you are given &quot;AT PILOTS DISCRETION.&quot; &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are a few different ways to equalize the pressure. The most effective is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Valsalva_maneuver&quot; rel=&quot;noreferrer&quot;&gt;valsava maneuver&lt;/a&gt;, which is how some scuba divers equalize the pressure as they descend into the water. Alternatively, yawning, chewing gum, sucking on hard candy, or hyperextending your jaw may help. Little children are particularly susceptible to discomfort, and parents will give them gum or candy at the beginning of the descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RKMNj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-20T21:14:25.460" LastActivityDate="2014-12-20T21:14:25.460" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11280" PostTypeId="2" ParentId="11271" CreationDate="2014-12-20T18:06:26.467" Score="10" Body="&lt;p&gt;When flying into a towered airport, you will be given specific instructions, as per the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0310.html&quot; rel=&quot;noreferrer&quot;&gt;ATC Handbook, Section 10, &lt;em&gt;Arrival Procedures and Separation&lt;/em&gt;&lt;/a&gt; such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;make left traffic for runway 15&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;enter a right base for runway 15&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;make straight-in runway 15&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can also request whatever you want, like: &quot;Tower, Cessna 3-3-Lima, information bravo, requesting left base for 15&quot;,&quot; and the controller will then evaluate your request and issue you instructions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These instructions refer to the following diagram form the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2013.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilots Handbook of Aeronautical Knowledge (PHAK, p. 13-12)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F1vs5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Traffic patterns are also covered in the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3b.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilots Flying Handbook, Chapter 7&lt;/a&gt;, and states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When operating at an airport with an operating control tower, the&#xA;  pilot receives, by radio, a clearance to approach or depart, as well&#xA;  as pertinent information about the traffic pattern.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which type of traffic pattern information ATC might give you, depends such factors as where you are relative to the airport, other traffic, noise abatement, obstructions, local procedure, etc.  For example, in the diagram below:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;N or NE of the airport, you could be given &quot;Left traffic&quot;&lt;/li&gt;&#xA;&lt;li&gt;NW you could be given a base entry&lt;/li&gt;&#xA;&lt;li&gt;W you could be given a straight in.&lt;/li&gt;&#xA;&lt;li&gt;If you're SW, S, or SE of the airport, you could be given the same pattern instructions as the north side, but with RIGHT instead of LEFT, or you could be instructed to overfly the field and enter, say, left downwind.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If you are in contact with ATC, and don't know what you're expected to do, then key the mic and ask the controller.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-22T23:42:55.403" LastActivityDate="2014-12-22T23:42:55.403" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11282" PostTypeId="2" ParentId="11272" CreationDate="2014-12-20T20:56:23.513" Score="6" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5300-13A-chg1-interactive.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 150/5300-13A&lt;/a&gt;, section 409: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. High-speed exit taxiways. A specific case of an acute angle runway&#xA;  exit taxiway that forms a 30-degree angle with the runway centerline&#xA;  is commonly referred to as a “highspeed” exit taxiway. The purpose of&#xA;  a high speed exit is to enhance airport capacity.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the parameters of high-speed taxiway design is the angle at which the taxiway intersects the runway, and does not take into account the aircraft speed, then the answer will be different for every aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-22T17:22:16.623" LastActivityDate="2014-12-22T17:22:16.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11283" PostTypeId="1" AcceptedAnswerId="11284" CreationDate="2014-12-20T22:09:18.143" Score="5" ViewCount="1232" Body="&lt;p&gt;If I punched a hole of the size of a small coin into the fuselage of a plane, and then covered it with the palm of my hand, what would it happen to my hand?&lt;/p&gt;&#xA;" OwnerUserId="3476" LastEditorUserId="97" LastEditDate="2015-04-22T00:38:47.623" LastActivityDate="2015-04-22T00:38:47.623" Title="What would happen if someone covered a small hole in the fuselage of a plane with a soft body part?" Tags="&lt;cabin-pressure&gt;&lt;fuselage&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11284" PostTypeId="2" ParentId="11283" CreationDate="2014-12-20T22:35:30.360" Score="17" Body="&lt;p&gt;I assume the hole has been properly deburred, otherwise you could suffer cuts on the sharp edges of the hole.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens else depends on altitude and flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low level, the outside temperature should be tolerable and the pressure difference between inside and outside should be small, so your hand will be fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher altitude, outside air temperature can drop to -60°C rsp. -76°F. Since air density is lower, the aircraft will travel fast (approx. 250 m/s rsp. 560 Mph in case of an airliner), and convective cooling at the hole will soon cause hypothermia and frost bites. Also, inside pressure is 0.6 bar rsp 8.8 lb/sq-in higher than outside pressure, and the exposed skin on your palm will feel this as a sucking sensation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I further assume that you need to remove all cabin insulation to put your hand over that hole, so your whole hand will be exposed to the airplane's metal skin which will have the same temperature as outside air. If the hand is dry and does not freeze to the metal skin, you might manage to keep it in place for a few seconds, but it will hurt. Keep it in contact with the metal skin longer and you will suffer progressive frostbite. The part of the skin which covers the hole should suffer less, since convective cooling should be less intense than the thermal conductivity of the metal skin, which will quickly pull all body heat from your hand where it touches the metal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure difference will not damage your hand, but the low temperature will.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-21T16:03:41.453" LastActivityDate="2014-12-21T16:03:41.453" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11285" PostTypeId="2" ParentId="8163" CreationDate="2014-12-21T00:04:26.003" Score="0" Body="&lt;p&gt;In addition to the requirement for multiple engines, the Caravan may also not meet the specs for emergency exits (FAR 23.807) and aisle width (FAR 23.815) that kick in from 10-19 passengers.&lt;/p&gt;&#xA;" OwnerUserId="4489" LastActivityDate="2014-12-21T00:04:26.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11286" PostTypeId="1" CreationDate="2014-12-21T01:41:40.833" Score="10" ViewCount="2297" Body="&lt;p&gt;Knowing the basic principle of a VOR and &lt;a href=&quot;http://www.digitalflightinstructor.com/how-a-vor-works/&quot; rel=&quot;nofollow&quot;&gt;how it works&lt;/a&gt;, I am interested to know how the &lt;strong&gt;receiver&lt;/strong&gt; works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly makes the needle deflect? And how does this deflecting mechanism know how much to deflect the needle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here is what I am thinking so far: since the signals are sine waves (I guess) and there are two of them, if you lay them over each other there should be a unique voltage for every direction from the VOR. To keep on guessing, this voltage is probably amplified and put onto a electric magnet that will then control the needle's deflection.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="13197" LastEditDate="2016-04-03T01:20:22.927" LastActivityDate="2016-04-03T01:20:22.927" Title="How does the VOR receiver pick up the signal and how are the needles controlled?" Tags="&lt;avionics&gt;&lt;vor&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11288" PostTypeId="2" ParentId="11265" CreationDate="2014-12-21T02:18:03.190" Score="12" Body="&lt;p&gt;In that case I would definitely report the incidence!  It doesn't have to be done by police, but you can give the airport authority a call, that way you don't have to make too much of a big deal about it, and still informed the ones that need to know. They can then advise pilots and keep their eyes open for it. If there is a attack on the airplanes, it is important that it is being reported before it is too late. If not, then you didn't make a big deal out of it and are not in trouble for wasting time and money. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, a call where you could explain what you have seen and give a opinion is your best bet, if they tell you off then hey, you've tried it!&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2014-12-21T02:18:03.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11289" PostTypeId="2" ParentId="11286" CreationDate="2014-12-21T05:56:02.950" Score="8" Body="&lt;p&gt;Your basic understanding of the underlying electronic principles is correct: The VOR receiver detects a phase offset between two signals, which tells the receiver what radial the aircraft is currently on. &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range#Operation&quot;&gt;Wikipedia has a decent explanation&lt;/a&gt;, and &lt;a href=&quot;http://www.digitalflightinstructor.com/how-a-vor-works/&quot;&gt;this article on Digital Flight Instructor has a nice widget you can play with to see the frequency offset&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The underlying electronic principles the receiver uses are generally not useful for pilots: if your VOR receiver dies you're not going to hook up an amplifier to an oscilloscope and try to sort out the phase offset yourself, if for no other reason than your head would be buried in the cockpit staring at the oscilloscope as opposed to looking out the window for traffic or watching your flight instruments.&lt;br&gt;&#xA;  In addition, the &quot;strobe and sweep&quot; explanation is generally easier for students to understand: Imagine the VOR station has two lights, a white light that rotates, and a red strobe that fires ever time the white light passes the 0 degree (North) radial. By counting the time between when you see the red strobe and when the white light passes you its possible to determine what radial you're on.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The mechanism by which the needle is deflected depends on the type of indicator, but it basically boils down to &quot;The receiver does some magic and converts it into a number of dots of deflection on the indicator&quot;. The deflection can displayed by moving needle attached to a meter (applying a specific positive or negative voltage), blinking some LEDs, or showing a graphical representation of the CDI (e.g. on a GPS display) with a mark over the appropriate dot.&lt;br&gt;&#xA;How this works for each specific indicator is generally only of interest to an avionics technician, and the information would be contained in the service manual for the radio and indicator.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-21T05:56:02.950" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11290" PostTypeId="1" AcceptedAnswerId="11291" CreationDate="2014-12-21T09:10:06.110" Score="2" ViewCount="152" Body="&lt;p&gt;Does ICAO require (or suggest) set of technical statuses of radar and its subsystems? In other words is it required that radar status can be set to &lt;code&gt;Normal&lt;/code&gt;, &lt;code&gt;Warning&lt;/code&gt; and &lt;code&gt;Error&lt;/code&gt;, or &lt;code&gt;Idle&lt;/code&gt;, &lt;code&gt;Alarm&lt;/code&gt;, &lt;code&gt;Unknown&lt;/code&gt; also possible? There are &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/service/content/documents/nm/asterix/cat002-asterix-monoradar-service-messages-part2b.pdf&quot; rel=&quot;nofollow&quot;&gt;002&lt;/a&gt; and &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/content/documents/nm/asterix/cat034-asterix-monoradar-service-messages-part-2b-next-version-of-cat-002.pdf&quot; rel=&quot;nofollow&quot;&gt;034&lt;/a&gt; categories of &lt;a href=&quot;https://www.eurocontrol.int/asterix&quot; rel=&quot;nofollow&quot;&gt;ASTERIX&lt;/a&gt; which describe messages about radar status, but I haven't found out answer on my question.&lt;/p&gt;&#xA;" OwnerUserId="2575" LastActivityDate="2016-07-11T11:17:40.180" Title="Does ICAO require (or suggest) set of technical statuses of radar and its subsystems?" Tags="&lt;radar&gt;&lt;icao&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11291" PostTypeId="2" ParentId="11290" CreationDate="2014-12-21T12:13:54.610" Score="2" Body="&lt;p&gt;These statuses are not defined by nor required explicitly by ICAO. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The details of how a radar (or other surveillance) system communicates with downstream ATC systems are defined in a technical specification documents, typically produced by EUROCAE and/or RTCA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ASTERIX specifications are maintained by EUROCONTROL and only give the format in which surveillance ground systems communicate amongst each other. The specifications were originally intended to facilitate surveillance data exchange between European countries, but they have now been adopted by many countries outside Europe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Category 002 (old) and 034 define the status messages monoradar systems use to update downstream systems (radar trackers, displays) on the radar's status. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-07-11T11:17:40.180" LastActivityDate="2016-07-11T11:17:40.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11292" PostTypeId="2" ParentId="11262" CreationDate="2014-12-21T13:02:15.603" Score="2" Body="&lt;p&gt;The word drone comes from 1935, where U.S. Adm. William H. Standley watched the DH 82B Queen Bee (one of the first remote controlled aircrafts!) presentation. As said by DavidC, a drone is a male bee, which is needed for reproduction only! The term drone was adopted though, as a homage to the Queen Bee. The term would also fit as the only way for the plane to function is by a controller on a &quot;mother&quot; plane or on the ground (lazy people were called drones in England at that time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is considered to be a drone now can obviously be approached differently! The FAA has its definitions, H. Dumpty has a very wide way of interpreting it, I guess. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it was misused by media a lot, the term drone must have been put on a lot of things, making a clear definition hard!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More information about the origin of the word &quot;&lt;a href=&quot;http://www.wsj.com/articles/SB10001424127887324110404578625803736954968&quot; rel=&quot;nofollow&quot;&gt;drone&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2014-12-21T13:02:15.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11293" PostTypeId="2" ParentId="9400" CreationDate="2014-12-21T14:14:56.747" Score="6" Body="&lt;p&gt;You can find interesting lectures about the refueling &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/170.pdf&quot; rel=&quot;nofollow&quot;&gt;in a Airbus Flight Operation Briefing Note&lt;/a&gt; or in the &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1206.pdf&quot; rel=&quot;nofollow&quot;&gt;CAP 748&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When they have children leave the plane, it is probably a company thing! There are no such rules that all passengers have to deboard a plane during refuel (with JetA and similar). But, as you can see in the Airbus FOPN, there are some requirements that need to be met. Each manufacturer as well as each company probably has its on way of interpreting  of the rules and regulations issued by the CAP and the FAA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summing up, it is basically by the pilots and therefore the company's discretion what to do with the passengers (or children) on board during refueling as long as saftey requirements are met!&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="3504" LastEditDate="2015-01-04T18:14:33.793" LastActivityDate="2015-01-04T18:14:33.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11294" PostTypeId="2" ParentId="140" CreationDate="2014-12-21T14:16:40.770" Score="16" Body="&lt;p&gt;Downward aileron travel must be restricted when flaps are deflected. Since flaps change the local incidence on the flapped part of the wing, the outer wing will experience an increase in its local angle of attack. The increased suction over the inner wing will accelerate not only the air flowing over the inner wing, but also that air which will flow over the outer wing as well. Left to itself, the outer wing would stall if powerful Fowler flaps are deployed on the inner wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3694/why-do-slats-deploy-first&quot;&gt;Adding slats will push the stall angle of attack up&lt;/a&gt;, and now the outer wing is back in business. However, if the aileron is deflected downwards, the stall angle of attack is reduced again. The outer wing could stall simply due to the aileron deflection!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not need to point out that an asymmetric stall on approach is extremely undesirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now roll control could still be achieved by only moving one aileron upwards. But this would decrease the induced drag at the wingtip at low speed. Remember, at low speed the induced drag is dominant (it is proportional to the inverse of the flight speed squared), so the drag change due to an aileron deflection will cause an inverse yawing moment at a time when the pilot wants to keep the aircraft lined up with the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the spoilers instead will incur a higher lift loss for the same rolling moment, but will also increase local drag, which creates a helpful yawing moment into the opposite direction of the one created by upward aileron deflection. Also, the change in local lift from spoiler deflection is much greater once the flaps are fully deployed. This means that spoilers are much more effective for roll control in the landing configuration than in the take-off or cruise configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;THAT&lt;/strong&gt;'s why spoilers are preferred for roll control on approach. I am surprised, however, that you observed no aileron motion at all. Normally, the ailerons are still used, but with a much restricted travel range, as @DeltaLima mentions in his answer.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-02-27T23:22:37.063" LastActivityDate="2019-02-27T23:22:37.063" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="11295" PostTypeId="1" AcceptedAnswerId="11305" CreationDate="2014-12-21T15:43:50.110" Score="7" ViewCount="1058" Body="&lt;p&gt;ANR (Active Noise Reduction) headsets reduce the sound level to a pilot's ears by creating an interference wave that cancels out some of the environmental noise in the cabin. Some say that this reduces the pilot's ability to hear minor changes in the engine's sound, thus delaying the point when the pilot would take action to diagnose the problem or land the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any conditions of engine malfunction or suboptimal performance which a pilot wearing an ANR headset would not be able to detect, but one wearing a passive headset would?&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-01-16T22:19:33.590" Title="Do ANR headsets affect pilots' perception of engine problems?" Tags="&lt;noise&gt;&lt;equipment&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11296" PostTypeId="2" ParentId="11295" CreationDate="2014-12-21T15:54:39.057" Score="3" Body="&lt;p&gt;When talking about GA, if (for example) one spark plug goes bad, you can actually notice a difference when listening closely, and i doubt you could hear that with ANR! But one spark plug that goes bad during flight is not gonna kill you (well, hopefully anyways!). If there is a problem that will cause major power loss on the engine, you will definitely hear it! Other things like engine roughness, which is primarily as sign for lack of carburetor heat might not be heard though. Yet, when flying with a normal headset I find it hard to hear when the engines sound changes over some time anyways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ANR headset will reduce, but not limit your ability to hear the engine. It is a lot more comfortable during cruise though.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2014-12-21T15:54:39.057" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11297" PostTypeId="1" AcceptedAnswerId="11298" CreationDate="2014-12-21T19:49:08.030" Score="5" ViewCount="1249" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Smart_material&quot; rel=&quot;nofollow&quot;&gt;Smart or Shape-memory materials&lt;/a&gt; have been known for quite long. What factors/limitations are put on it for applications in aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For someone who doesn't know much about its material properties, it seems quite good to have deforming wing or other parts and seem to improve aircraft performance. (One example might be: suitable wing geometry deformation according to aircraft's speed regime)&lt;/p&gt;&#xA;" OwnerUserId="3276" LastEditorUserId="97" LastEditDate="2015-04-22T00:36:27.390" LastActivityDate="2015-06-17T14:45:14.210" Title="How feasible is it to use Smart Materials on aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11298" PostTypeId="2" ParentId="11297" CreationDate="2014-12-21T20:55:43.453" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Shape-memory_alloy&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shape-memory alloys&lt;/a&gt; are only a small part of smart materials. Once deformed, they will change back to their old shape when heated or subjected to strong magnetic fields. Of the many alloys with this characteristic, only a few like &lt;a href=&quot;http://en.wikipedia.org/wiki/Nickel_titanium&quot; rel=&quot;nofollow noreferrer&quot;&gt;nickel-titanium&lt;/a&gt; would be suitable for primary structures. They are extremely expensive to make and to process, so they have never been an economical alternative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, heating and cooling would be required to switch between shapes, which is very energy intensive when the outer structure of an aircraft is involved. Airflow will ensure intense convective heat transfer, and to maintain the needed temperature will be very uneconomical. Please consider that an aircraft with shape-memory alloys would need to carry extra fuel for heating or cooling over much of the flight time. Hinges and electric or hydraulic actuators will have a clear mass advantage when you consider the system mass, including energy sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess you agree that creating strong magentical fields in parts of an aircraft is an exceedingly bad idea, so I will rule out &lt;a href=&quot;http://en.wikipedia.org/wiki/Magnetic_shape-memory_alloy&quot; rel=&quot;nofollow noreferrer&quot;&gt;magnetic shape-memory alloys&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shape-memory alloys will only switch between two shapes, and intermediate shapes are easier to realize with hinges and actuators. Sure, a smooth shape is aerodynamically better than one with a contour break at the hinge line, but the small aerodynamic advantage of shape-memory structures is quickly lost when you look at the whole picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another disadvantage is the accumulation of small cracks with every shape change. The low number of cycles will either require frequent replacement of the shape-memory parts or a very limited structural life of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, much of what can be said about &lt;a href=&quot;https://aviation.stackexchange.com/questions/8271/bae-smart-skin-aviation-implications&quot;&gt;other smart materials&lt;/a&gt; also applies to shape-memory alloys. Their main function is to justify research grants and to keep the press occupied.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2014-12-21T21:02:21.880" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11300" PostTypeId="1" CreationDate="2014-12-22T12:22:11.823" Score="6" ViewCount="1716" Body="&lt;p&gt;I live near an airbase and use an ADS-B receiver that picks up aircraft using regular ICAO assignments. They do not include flight path details or position info, but can be identified by the ICAO number which is a civilian aircraft identifier. Sometimes, it captures aircraft SSR returns with what appear to be invalid numbers, beginning with FF followed by 4 digits, such as FF0024 FF7777. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these drones? cruise missiles? Aurora? Or some other military aircraft identity?  &lt;/p&gt;&#xA;" OwnerUserId="5598" LastEditorUserId="3504" LastEditDate="2014-12-22T14:34:47.480" LastActivityDate="2014-12-22T18:07:08.970" Title="What kind of ADS-B identification code is FFxxxx, where xxxx are numbers i.e. FF0024?" Tags="&lt;ads-b&gt;&lt;plane-spotting&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11301" PostTypeId="2" ParentId="1176" CreationDate="2014-12-22T14:04:03.827" Score="2" Body="&lt;p&gt;Some new Rotax engines, such as the &lt;a href=&quot;http://www.flyrotax.com/enginesImpressum/product-rangeImpressum/InjectedImpressum/912-iS-100hpImpressum/Description.aspx&quot; rel=&quot;nofollow&quot;&gt;912 iS&lt;/a&gt;, are fuel-injected and include a &lt;a href=&quot;http://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;Full Authority Digital Engine Control (FADEC)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FADEC works by receiving multiple input variables of the current&#xA;  flight condition including air density, throttle lever position,&#xA;  engine temperatures, engine pressures, and many other parameters. The&#xA;  inputs are received by the EEC and analyzed up to 70 times per second.&#xA;  Engine operating parameters such as fuel flow, stator vane position,&#xA;  bleed valve position, and others are computed from this data and&#xA;  applied as appropriate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="938" LastEditDate="2014-12-23T17:42:34.460" LastActivityDate="2014-12-23T17:42:34.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11302" PostTypeId="2" ParentId="11300" CreationDate="2014-12-22T14:36:08.170" Score="4" Body="&lt;p&gt;If these are 24-bit ICAO aircraft addresses, then they belong to an unallocated part of the address space. Several places on the net (&lt;a href=&quot;http://www.ais-netherlands.nl/aim/091203-100114/eAIP/html/eAIC/EH-eAIC-04-23-B_en-en-GB.html&quot; rel=&quot;nofollow&quot;&gt;1&lt;/a&gt;, &lt;a href=&quot;http://www.kloth.net/radio/icao24alloc.php&quot; rel=&quot;nofollow&quot;&gt;2&lt;/a&gt;) document that addresses starting with F are reserved for future use by ICAO. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The referenced documents, however, pre-date the widespread development and deployment of UAVs, and other sources on the net (e.g. &lt;a href=&quot;http://adsb.tc.faa.gov/ICAO-TSG/TSG26-Paris-2013/ASP%20TSGWP15-18-ACAS%20Xu_UAS%20Address%20Block.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://adsb.tc.faa.gov/ICAO-ASP/ASP15-Montreal-13/WP%20ASP15-12-UASblock.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;) indicate that &quot;high-order&quot; 24-bit addresses (which apparently means ones starting with F) are to be used for UAVs equipped with &quot;ACAS Xu&quot;, a collision avoidance system (currently under development? testing?) which uses the same ADS-B compatible radio protocol as ordinary ACAS/TCAS systems, but &lt;a href=&quot;http://aviationweek.com/awin/unmanned-community-making-progress-airspace-access&quot; rel=&quot;nofollow&quot;&gt;cannot send interrogations&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point of using addresses starting with F (rather than allocating addresses out of the nationally assigned range for the drone's country of origin) seems to be that the ACAS protocol uses &quot;which aircraft has the higher address&quot; as one of the inputs in coordinating which resolution advisory to issue. If a drone and an ordinary ACAS II equipped aircraft are converging, there's a risk that both ACAS systems would issue &quot;climb&quot; advisories (or both would issue &quot;descend&quot;) and be technically unable to change it &lt;em&gt;unless&lt;/em&gt; the drone has a higher address. At least, that's what I get from the sources linked above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;s&gt;So your FFxxxx traffic, if you're sure they are 24-bit addresses, are probably drones exchanging ACAS reports with nearby aircraft.&lt;/s&gt; &lt;em&gt;(DeltaLima's answer looks more convincing.)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2014-12-22T18:07:08.970" LastActivityDate="2014-12-22T18:07:08.970" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11303" PostTypeId="2" ParentId="11300" CreationDate="2014-12-22T15:09:41.170" Score="9" Body="&lt;p&gt;I am going to assume you use &lt;a href=&quot;https://github.com/flightaware/dump1090_mr&quot;&gt;Flightaware's variety of dump1090&lt;/a&gt; as a decoder. &#xA;When that receives a Mode A code, it publishes it as if it were a 24 bit address. The first two hexadecimal digits are filled with 'FF'. I have no idea why this may be a good plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;code&gt;mode_ac.c&lt;/code&gt;, lines 368-370:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;// Fudge an ICAO address based on Mode A (remove the Ident bit)&#xA;// Use an upper address byte of FF, since this is ICAO unallocated&#xA;mm-&gt;addr = 0x00FF0000 | (ModeA &amp;amp; 0x0000FF7F);&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These may be drones but most likely they are just simple aircraft replying to Mode A/C interrogations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in the USA, FF7777 is a field test transponder (Range &amp;amp; Azimuth Beacon Monitor, RABM) , usually located not far from a radar to verify the correct working of the radar. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-22T15:15:59.847" LastActivityDate="2014-12-22T15:15:59.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11304" PostTypeId="2" ParentId="11295" CreationDate="2014-12-22T15:27:33.940" Score="8" Body="&lt;p&gt;Although its possible to detect engine problems audibly, I don't think that's the primary mechanism (except for engine out) by which pilots are expected to detect engine anomalies. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.205&quot;&gt;Part 91.205&lt;/a&gt; requires that every aircraft be equipped with the following instrumentation, and these should be the primary mechanism by which engine malfunctions are detected. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(4) Tachometer for each engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Oil pressure gauge for each engine using pressure system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) Temperature gauge for each liquid-cooled engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) Oil temperature gauge for each air-cooled engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(8) Manifold pressure gauge for each altitude engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(9) Fuel gauge indicating the quantity of fuel in each tank.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, ANR headsets &lt;em&gt;attenuate&lt;/em&gt; sound, but don't eliminate it entirely. Having flown with an ANR headset for most of my flying career, I can certainly hear variations in engine noise in the mag check and prop exercise during the runup, as well as during throttle and prop changes. I can also hear a fouled plug during runup, as well as verifying it visually on the gauges.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-22T15:44:29.400" LastActivityDate="2014-12-22T15:44:29.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11305" PostTypeId="2" ParentId="11295" CreationDate="2014-12-22T15:50:40.113" Score="8" Body="&lt;p&gt;In summary, based on FAA/NTSB information it's possible in theory but no one really knows how individual headsets behave and there's no record of ANR headsets contributing to an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, according to a very short FAA &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2007/info07001.pdf&quot; rel=&quot;nofollow&quot;&gt;information paper&lt;/a&gt; on &lt;em&gt;Noise Attenuation Properties of Noise-Canceling Headsets&lt;/em&gt;, it's possible that they can mask important sounds:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While this technology can have many beneficial effects such as&#xA;  providing clearer communications, reduced pilot fatigue, and added&#xA;  comfort, electronic attenuation of important environmental sounds and&#xA;  alarms may occur&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the paper has no specific information or examples, and its only purpose seems to be to encourage operators to do their own testing (which is reasonable, since headsets can be very different):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Evaluations should be conducted while both on the ground and in flight&#xA;  during normal operating conditions to ascertain if any audible alarms&#xA;  or other environmental sounds, or combinations thereof, can be&#xA;  detected while electronic noise attenuation is on and active.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That paper is from 2007 and a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2007/whatley%20-%20(2007)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow&quot;&gt;letter of interpretation&lt;/a&gt; from the same year on headset requirements in part 121 operations implies that the FAA's main concern with ANR headsets is (or was) that the batteries run out and that might cause problems:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA is particularly concerned, however, that Active Noise&#xA;  Reduction (ANR) headsets and headset adapters [...] that rely on&#xA;  battery power are subject to failure when [...] batteries discharge&#xA;  under normal use&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the FAA's general &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/hearing_brochure.pdf&quot; rel=&quot;nofollow&quot;&gt;brochure&lt;/a&gt; on &lt;em&gt;Hearing and Noise in Aviation&lt;/em&gt; mentions ANR headsets without any warnings or recommendations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the NTSB's accident database has only one &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/GeneratePDF.aspx?id=ANC98MA008&amp;amp;rpt=fa&quot; rel=&quot;nofollow&quot;&gt;specific reference&lt;/a&gt; to an ANR headset (that I could find) and it explicitly ruled out any effect:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On January 5, 1998, the NTSB IIC used a Cessna 208B to determine if&#xA;  the Telex model ANR-4100 active noise reduction headset worn by the&#xA;  pilot at the time of the accident could have eliminated his ability to&#xA;  hear stall or fuel selector warning horns. All aural warnings were&#xA;  clearly audible with the engine operating and the headset active.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The information I found online on ANR headsets is overwhelmingly positive and I couldn't find any informal reports of pilots mishearing engine sounds either.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-16T22:19:33.590" LastActivityDate="2015-01-16T22:19:33.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11306" PostTypeId="2" ParentId="1363" CreationDate="2014-12-22T16:46:54.453" Score="2" Body="&lt;p&gt;Adding to the previous answers (very detailed, solid ones, I might add), it's good to ask around about the examiners in your area. They do differ in personality which can affect your experience. The best examiners make you comfortable enough to perform to the best of your ability. In my flying club (which licensed six new pilots this year of of a total of 30 members), most of us went with one DPE. One of the six, however, had some friction with that DPE and got his ticket with one of the other DPEs. &lt;/p&gt;&#xA;" OwnerUserId="3211" LastActivityDate="2014-12-22T16:46:54.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11307" PostTypeId="2" ParentId="11265" CreationDate="2014-12-22T16:59:59.330" Score="7" Body="&lt;p&gt;The FAA &lt;a href=&quot;http://www.faa.gov/aircraft/safety/report/laserinfo/&quot;&gt;encourages report&lt;/a&gt;s of laser incidents. They focus on ground observers and pilots, but I think a passenger report would be useful too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Austro Control site does offer &lt;a href=&quot;http://www.austrocontrol.at/en/aviation_agency/safety/reporting/reporting_tool&quot;&gt;reporting forms&lt;/a&gt; for various safety purposes, including a &quot;voluntary/simplified&quot; report, which could be a place to start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with most reports, nothing will probably happen, but it can help in identifying &lt;a href=&quot;http://www.fbi.gov/tampa/press-releases/2012/orlando-man-pleads-guilty-to-aiming-a-laser-at-airliners-departing-from-orlando-international-airport&quot;&gt;repeat offenders&lt;/a&gt; and keeping statistics. Laser incidents are being taken more and more seriously. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_70-2A_.pdf&quot;&gt;The FAA asks&lt;/a&gt; pilots to immediately report any incidents to ATC, and when applicable ATC is required to provide a caution every five minutes for 20 minutes and include a warning in ATIS for at least 1 hour. Of course, reports immediately after an incident with accurate position information will be the most useful.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-22T22:02:40.670" LastActivityDate="2014-12-22T22:02:40.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11308" PostTypeId="2" ParentId="11265" CreationDate="2014-12-22T17:23:50.477" Score="0" Body="&lt;p&gt;I would not report it.  Most likely the pilots saw it too, and it is their responsibility to report this.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is necessary is to get the report made in close to real time so the authorities can pinpoint the location.  Now, hours even days in arrears, your report would not be useful.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-12-22T17:23:50.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11309" PostTypeId="1" CreationDate="2014-12-22T17:39:22.757" Score="3" ViewCount="4043" Body="&lt;p&gt;I'm thinking of buying a taildragger LSA, many of which have a Rotax engine. Continental and Lycoming are the major suppliers of certified piston aircraft engines, and they are considered to be safe engines (for pistons!). I'm wondering if I should consider the safety and reliability of the certified Rotax engine to be substantially worse than that of the Conti O-200 (the only other certified LSA engine), and if there is any evidence one way or the other. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2014-12-29T16:30:07.340" Title="How safe is the Certified Rotax 912 versus the Continental O-200?" Tags="&lt;safety&gt;&lt;piston-engine&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11310" PostTypeId="1" AcceptedAnswerId="11313" CreationDate="2014-12-22T17:46:36.633" Score="21" ViewCount="1833" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=3zBdtNVa8N0&quot; rel=&quot;nofollow noreferrer&quot;&gt;This incident at O'Hare from July 2006&lt;/a&gt; made me wonder what information is available to a pilot (specifically, in an airliner) regarding aircraft that are using an intersecting runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this incident, the controller had a United 737 line up and wait on 27L because the United flight wasn't ready to go yet while an Atlas 747 was on final for 14R. Once the United pilots radioed that they were ready, tower cleared them for takeoff on 27L, despite the fact that the Atlas 747 was touching down on 14R and was about to cross 27L on the roll-out. The Atlas flight did call out that he was on final, but that's the only indication I can see from the video that the United pilot has regarding the position of the Atlas flight. Judging from the below airport diagram, it appears that the ORD terminal would have been between the two aircraft at the time the United pilot was cleared for takeoff, so the aircraft wouldn't have been able to see each other until they approached the intersection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QLzim.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QLzim.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the controller shouldn't have cleared the United flight for departure until Atlas was out of the way. However, given that he received the takeoff clearance from Tower, I'm wondering whether the United pilot would have had any other tools at his disposal to detect the position of the Atlas 747 and realize that the controller made a mistake (before he saw a giant 747 roll out in front of him on the runway and before the controller realized his mistake.) Specifically, do airline pilots have any additional means for determining the position of other aircraft on intersecting runways aside from relying on ATC, listening to the Tower frequency, and looking out the window?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware of &lt;a href=&quot;http://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TCAS&lt;/a&gt; for use in-flight, but I'm not familiar enough with it to know if it would help in an intersecting runway situation like this where both aircraft are on the ground.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="14897" LastEditDate="2017-05-04T00:19:00.510" LastActivityDate="2017-05-04T00:19:00.510" Title="What information does a pilot have about aircraft operating on an intersecting runway?" Tags="&lt;safety&gt;&lt;separation&gt;&lt;intersecting-runways&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11312" PostTypeId="2" ParentId="11266" CreationDate="2014-12-22T18:00:40.667" Score="11" Body="&lt;p&gt;The answer depends on the strength of the EMP at the aircraft location. This obviously depends on the distance from origin and strength at source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft do have some immunity from EMP, they don't just fall from the sky if you make sparks with a 12V car battery 35,000 feet below them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an extract from &lt;em&gt;&lt;a href=&quot;https://books.google.co.uk/books?id=Vwx96p5SGg8C&amp;amp;pg=PA125&amp;amp;lpg=PA125&quot; rel=&quot;noreferrer&quot;&gt;Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack&lt;/a&gt;&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IRoC1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rSL1h.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sup&gt;&lt;em&gt;EMP simulator HAGII-C testing a Boeing E-4 aircraft. (&lt;a href=&quot;http://en.wikipedia.org/wiki/Electromagnetic_pulse&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read that many modern FBW aircraft (including Airbus and Boeing) still have some fallback manual control of basic flight controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if &lt;em&gt;all&lt;/em&gt; your navigation and communication systems are fried and ATC is completely  dead, your chances of gliding to an essentially uncontrolled nearby airfield and making a good landing must be quite small. Especially at night, in the rain, with a new moon.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-12-22T18:00:40.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11313" PostTypeId="2" ParentId="11310" CreationDate="2014-12-22T18:38:00.200" Score="14" Body="&lt;p&gt;As the question mentions, good situational awareness is an excellent safety tool. ATC is responsible for runway separation at towered airports, but pilots can play an important part of backup in the case of a human mistake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The United pilots may or may not have been able to see the Atlas 747 on TCAS, as the terminal building that obstructed their view could also have blocked the transponder signal. TIS-B (Traffic Information Systems - Broadcast), a part of ADS-B, provides traffic both in the air and on the ground. ADS-B was not available in 1996, but if the same situation happened today and the United aircraft had an ADS-B signal on the surface and displayed TIS-B information, they would see the Atlas 747 on their displays. Whether or not that information would be useful to avoid an incursion in a cluttered runway environment is unclear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA is implementing a system to provide exactly the type of warning you're describing. &lt;a href=&quot;https://www.faa.gov/air_traffic/technology/rwsl/&quot; rel=&quot;noreferrer&quot;&gt;Runway Status Lights (RWSL)&lt;/a&gt; use surface RADAR and lights embedded in the pavement to detect conflicts and alert pilots that a runway is unsafe to enter or take off from. In this situation, the United pilots would have seen red takeoff hold lights to inform them that the runway is unsafe for departure. The FAA plans to have RWSL operational in 17 airports, including Chicago O'Hare, by 2017.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2014-12-23T04:32:06.850" LastActivityDate="2014-12-23T04:32:06.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11314" PostTypeId="2" ParentId="11310" CreationDate="2014-12-22T18:55:05.567" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Specifically, do airline pilots have any additional means for&#xA;  determining the position of other aircraft on intersecting runways&#xA;  aside from relying on ATC, listening to the Tower frequency, and&#xA;  looking out the window?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically the answer is no. The only thing that could have been of help is TCAS, however:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft on the ground are not visible on TCAS; the Atlas 747's TCAS would be unable to see the United 737 on the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;TCAS works line of sight, if the Atlas 747 was obscured by the terminal there is high probability that the aircraft was not visible to the United 737's TCAS system. If it was, the range and direction measurements were unreliable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some airports have Advance Surface Movement Guidance &amp;amp; Control Systems (A-SMGCS) that indicate whether runways and taxiways are safe to use. However only the highest level (A-SMGCS level 4: Conflict Resolution, Automatic Planning &amp;amp; Guidance) includes automatic guidance for the pilots, lower levels only provide guidance to controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the future ADS-B will be of help. In 2020 all commercial aircraft in the US will be equipped with ADS-B OUT. To display the traffic information in the cockpit, aircraft need to be equipped with ADS-B IN as well. As it stands, equipping with ADS-B IN is voluntary. Just like TCAS, ADS-B works line off sight. However, airports are likely to install re-transmitters at strategic points to overcome signal obstruction by buildings. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-22T19:04:39.277" LastActivityDate="2014-12-22T19:04:39.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11315" PostTypeId="1" AcceptedAnswerId="11317" CreationDate="2014-12-22T19:07:05.810" Score="8" ViewCount="1494" Body="&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/questions/8432/what-is-the-advantage-of-the-two-part-rudder-and-how-does-it-work&quot;&gt;question&lt;/a&gt; (which is the first result for a Google search for &quot;Split rudder aircraft&quot;, btw), talks about some of the advantages of the split rudder, including the fact that the lower rudder is smaller for finer adjustments while flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the rudders were equal size, or if there were three pieces, two of them being equal to the third, could they be used as an air brake? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would there be advantages to doing so vs building in a dedicated air brake?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2014-12-22T19:15:24.647" Title="Is it possible to use a split rudder as an air brake?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11316" PostTypeId="2" ParentId="11315" CreationDate="2014-12-22T19:13:31.373" Score="4" Body="&lt;p&gt;Yes, a split rudder can be used as a speed brake.  The early versions of the Beech Staggerwing and the space shuttle both have split rudders utilized for speed brakes.&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2014-12-22T19:13:31.373" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11317" PostTypeId="2" ParentId="11315" CreationDate="2014-12-22T19:15:24.647" Score="11" Body="&lt;p&gt;It is possible but there are side effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both rudders would be deflected to opposite sides to cancel out each others yaw moments, their drag will act as an air brake. But since the top rudder is further from the center of gravity than the bottom rudder, the resulting roll moments of the rudders don't cancel each other out. As a result the aircraft will start to roll. This can then be counteracted with the ailerons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the rudders don't deflect as far as air brakes would, they would be less effective. If they would be designed to deflect more, the increased forces upon them and on the control system would require a heavier construction and thus add weight to the aircraft. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2014-12-22T19:15:24.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11318" PostTypeId="1" AcceptedAnswerId="11321" CreationDate="2014-12-22T21:25:35.720" Score="65" ViewCount="14699" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/q/11310&quot;&gt;What information does a pilot have about aircraft operating on an intersecting runway?&lt;/a&gt; and noticed this on the map:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RsKYI.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RsKYI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.airnav.com/airport/KORD&quot; rel=&quot;noreferrer&quot;&gt;airnav.com&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is a &quot;penalty box&quot; marked on the map? What is it? What is it used for?&lt;/p&gt;&#xA;" OwnerUserId="14" LastEditorUserId="14" LastEditDate="2017-12-20T05:25:35.923" LastActivityDate="2017-12-20T05:25:35.923" Title="Why does Chicago O'Hare have a penalty box?" Tags="&lt;airport&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11319" PostTypeId="2" ParentId="11318" CreationDate="2014-12-22T21:45:41.593" Score="37" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/airports/airport_development/omp/planning/MP/OAMP/Media/Section_II-Inventory-03.pdf&quot;&gt;As described by FAA&lt;/a&gt;, it seems like it is for holding aircraft when gate is not available:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Penalty Box is located adjacent to the terminal perimeter Taxiway B, east of Concourse C. &lt;strong&gt;Arriving aircraft typically use this position to wait for gate clearing&lt;/strong&gt;. The pad is able to accommodate ADG IV and smaller aircraft (i.e., no heavy jets with the exception of DC-10 and B-767). No aircraft may occupy the Penalty Box during landings on Runway 4L.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="679" LastEditorUserId="65" LastEditDate="2014-12-22T21:59:49.387" LastActivityDate="2014-12-22T21:59:49.387" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11320" PostTypeId="1" CreationDate="2014-12-22T21:54:59.363" Score="10" ViewCount="1420" Body="&lt;p&gt;Airships are unstable in pitch above a certain speed, called the critical speed. What causes the instability, how does it manifest itself for the pilot, and how is the critical speed defined and determined?&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-23T22:29:27.440" LastActivityDate="2015-07-30T10:16:20.717" Title="Longitudinal stability of airships: How is the critical speed defined?" Tags="&lt;airship&gt;&lt;stability&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11321" PostTypeId="2" ParentId="11318" CreationDate="2014-12-22T22:19:22.733" Score="42" Body="&lt;p&gt;In addition to what vasin mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/questions/11318/why-does-chicago-ohare-have-a-penalty-box/11319#11319&quot;&gt;his answer&lt;/a&gt;, a mechanic from O'Hare mentioned hearing ATC direct aircraft to go there when they weren't ready for takeoff by the time they got to the runway in a comment on the &lt;a href=&quot;https://www.youtube.com/watch?v=3zBdtNVa8N0&quot; rel=&quot;noreferrer&quot;&gt;video that prompted the linked question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;They [the pilot of the aircraft not yet ready for departure] sheepishly called and told the tower that they'd need another moment or two before takeoff. The controller goes...&quot;Uh....yeah, no.....cross Runway two-seven left and hold in the penalty box. We'll be in touch.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apparently ATC doesn't like you holding up the line of departing traffic at ORD.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As mentioned in the comments, the concept of having a paved area on or near the taxiways for planes to park while waiting to be ready for departure, waiting for a gate, or other similar uses is not unique to O'Hare. Most significantly-sized commercial airports have such areas. The primary thing that is unique about O'Hare's is just that it's named and the name is on the airport diagram. And perhaps also this particular controller's snarky sense of humor.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-12-24T08:17:45.090" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11322" PostTypeId="1" AcceptedAnswerId="11323" CreationDate="2014-12-22T22:44:59.067" Score="11" ViewCount="1513" Body="&lt;p&gt;I'm not sure if this is the best place, or physics.SE would a better place. I guess the aerospace engineers might be on both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In class we were talking about stability of the boundary layer, and the influence of the temperature on the boundary layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The governing equation is given by &lt;a href=&quot;http://en.wikipedia.org/wiki/Boundary_layer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wiki boundary layer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ u{\partial u \over \partial x}+\upsilon{\partial u \over \partial y}=-{1\over \rho} {\partial p \over \partial x}+{\nu}{\partial^2 u\over \partial y^2} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we evaluate this $y=0$, where both $u$ and $v$ are zero:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$${1\over \rho} {\partial p \over \partial x}={\nu}{\partial^2 u\over \partial y^2} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We then deduced that, since $\nu=f(T)$, the instabilitiy of a boundary layer is thus a function of the temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of us mentioned that this was the reason that the Pepsi-livery Concorde had a lower maximum operating speed, since it is not white, but blue: &lt;img src=&quot;https://i.stack.imgur.com/b7eXT.jpg&quot; alt=&quot;Pepsi-Concord&quot;&gt; &#xA;This would increase the temperature at the wing, making the boundary layer less stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did so a search, which brought me to this &lt;a href=&quot;http://www.concordesst.com/history/events/pepsi.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Concorde SST website&lt;/a&gt;, which says that the wings were kept white, to reduce the temperature of the wing, but because of the fuel temperature. As the wings are white, the effects we were talking about are not relevant anymore, but still it made me wonder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Could the color of a surface have so much influence on the stability of the boundary layer?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="19" LastEditDate="2017-05-05T09:02:11.407" LastActivityDate="2017-05-05T09:02:11.407" Title="How big is the influence of color on the stability of the boundary layer?" Tags="&lt;aerodynamics&gt;&lt;concorde&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11323" PostTypeId="2" ParentId="11322" CreationDate="2014-12-22T23:02:25.423" Score="8" Body="&lt;p&gt;Technically, yes. Practically, no.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Boundary layer stability&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You are right that boundary layer stability depends on viscosity, but it depends much more on the pressure gradient. Accelerating flow exhibits extreme stability: Even if there is movement orthogonal to the flow direction (due to &lt;a href=&quot;http://en.wikipedia.org/wiki/Tollmien%E2%80%93Schlichting_wave&quot; rel=&quot;nofollow&quot;&gt;Tollmien-Schlichting waves&lt;/a&gt;), their speed becomes an ever smaller fraction of flow speed in accelerating flow. This kind of flow is always found right after the stagnation point, when the suction area over the mid section of the wing accelerates flow into it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, decelerating flow has lower stability: Now any crossflow becomes relatively stronger simply because flow speed is decreasing. This kind of flow is found aft of the suction peak, when the flow has to manage the long and arduous pressure rise to the trailing edge. It does not take long, and transition into turbulent flow happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Concorde at high angle of attack, lift was created by a strong &lt;a href=&quot;http://en.wikipedia.org/wiki/Vortex_lift&quot; rel=&quot;nofollow&quot;&gt;vortex&lt;/a&gt;. The boundary layer became turbulent right after the leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cruise, the flow would hit the leading edge at a small angle, so the speed distribution over the wing was less peaky. The long chord length and high flow speed would still cause an early transition, however, so most of the wing had turbulent flow. Indeed, cooling the wing would lengthen the laminar portion, and heating would shorten it, but the difference in friction drag would be small when looking at the full picture.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Air temperature over the wing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In supersonic flow you always have both a temperature boundary layer and a viscous boundary layer. Air is heated when compressed and cools when it expands, and in supersonic flow these effects become too large to be ignored. Also, friction in the boundary layer heats up the air near the wing's surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stagnation temperature increase at Mach 2 is 173°C. The leading edge temperature can be expected to be around 120°C (standard atmosphere air temperature being at -56°C in FL 600). Past the stagnation point, the flow accelerates into a suction field in which air temperature drops below its ambient value. At the bottom of the boundary layer, however, the temperature stays almost as high as at the stagnation point due to frictional heating. In a turbulent boundary layer on a flat plate the frictional effect would increase temperature by 152°C. Without the pressure distribution over the wing I cannot give a value for the absolute temperature, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to heat transfer with the wing, the air is cooled over much of the wing in the vicinity of the wing's surface. A dark coating will add a few degrees and result in a higher equilibrium temperature over much of the wing. A hotter boundary layer is thicker due to the expansion of air with temperature and will have higher viscosity. The most simple explanation why viscosity increases with temperature is that the mean molecular velocities, which are &lt;a href=&quot;http://en.wikipedia.org/wiki/Molecular_modelling&quot; rel=&quot;nofollow&quot;&gt;directly related to temperature&lt;/a&gt;, facilitate more transfer of shear forces between molecules. However, when it comes to wall friction, the effect of lower density with temperature outweighs the increase in viscosity, and wall friction is lower in a hotter boundary layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, a heated boundary layer shows earlier transition and lower friction drag. The dark paint should actually help to lower the friction losses, and since the influence of temperature on the transition point is small, the change in friction due to lower density at the wall should dominate. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Maximum wing temperature&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The maximum speed of the Concorde was limited by the stagnation temperature of air. If we assume that a switch from white to dark blue paint increases the equilibrium temperature of the wing leading edge by 10°C (which is not unreasonable), this increase could be compensated by a reduction of the maximum flight Mach number from 2.0 to 1.94. A restriction of the Pepsi Concorde to Mach 1.7 seems to me to be the result of extreme (and unreasonable) caution.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;My verdict&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I did not run the numbers, but I would expect that a different paint job would not change wing temperature much. At the leading edge and over much of the wing it adds a little to aerodynamic heating. A warmer wing would translate into less friction, but the difference is extremely small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground, in the absence of the strong convective heat transfer during supersonic flight, the temperature difference between white and dark wings is much more pronounced (in the order of 30°C to 50°C), and in this case a white wing is very effective in keeping the fuel temperature down and avoiding gas bubbles in the fuel line.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-26T11:48:42.813" LastActivityDate="2014-12-26T11:48:42.813" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11324" PostTypeId="2" ParentId="8163" CreationDate="2014-12-23T00:01:11.160" Score="2" Body="&lt;p&gt;Cessna 208 is certified for FAR 23 &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/c3b17c7c7390ec3686257b9000723e14/$FILE/A37CE_Rev_20.pdf&quot; rel=&quot;nofollow&quot;&gt;from amendment 23-1 to 23-28&lt;/a&gt; for up to 9 passengers and crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 23.3 (d) allows for up to 19 passengers and crews was amended in 2012 in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/AB51E741104F7C1686257996006CAD44?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;amendment 23-62&lt;/a&gt; however it requires multiengine plane and not applicable to the 208.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence 208 is not qualified to fly more than 9 passengers without the waiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional reading material:&#xA;Cessna brochure suggest that passenger limit is &lt;a href=&quot;http://cessna.txtav.com/~/media/Files/caravan/amphibian/Caravan%20675%202013%20OEG.ashx&quot; rel=&quot;nofollow&quot;&gt;14 with appropiate waiver&lt;/a&gt; and &lt;strong&gt;not compatible with aircraft operate on US registry.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2014-12-23T00:01:11.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11325" PostTypeId="2" ParentId="11320" CreationDate="2014-12-23T00:09:05.317" Score="11" Body="&lt;p&gt;On page 43 of the &lt;a href=&quot;https://books.google.de/books?id=cCNxBQAAQBAJ&amp;amp;pg=PA44&amp;amp;dq=critical%20speed%20airship&amp;amp;hl=nl&amp;amp;sa=X&amp;amp;ei=na-YVNu0Coj1OMakgbAG&amp;amp;ved=0CCIQ6AEwAA#v=onepage&amp;amp;q=critical%20speed%20airship&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;Technical Manual of Airship Aerodynamics&lt;/a&gt; I found the following image:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/FKuk8.png&quot; alt=&quot;Airship Free Body Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here $F_e$ is the resultant airforce on the hull, or the dynamical lift of the hull. As this is before the CoG, it is destabilizing.&#xA;This source mentions Munk's formula being:&#xA;$$ M_e = Volume \cdot 0.5 \rho V^2 (k_2-k_1) \sin{2\theta} $$&#xA;Where $k_2$ and $k_1$ indicate the effect of gas movement inside the airship.&#xA;I tried to trace the origin of this formula in Munk's paper, available &lt;a href=&quot;https://archive.org/details/nasa_techdoc_19800006780&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, but I can't immediately find a clear explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The critical speed is reached when this resultant airforce equals the moment induced by the weight:&#xA;$$Wh\sin{(\alpha + \theta)}=Volume \cdot 0.5 \rho V^2 (k_2-k_1) \sin{2\theta}$$  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this sense, the critical speed is the maximum speed at which the gravity moment is able to compensate the moment induced by dynamical lift. As such, one should stay below the critical speed.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2014-12-23T11:45:56.583" LastActivityDate="2014-12-23T11:45:56.583" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11326" PostTypeId="1" AcceptedAnswerId="11335" CreationDate="2014-12-23T02:45:24.970" Score="10" ViewCount="1264" Body="&lt;p&gt;The early Wright Flyer famously used &lt;a href=&quot;http://wright.nasa.gov/airplane/warp.html&quot;&gt;wing warping&lt;/a&gt; for its roll control surfaces. This technology was soon abandoned in favor of ailerons and by the end of the biplane era, was not used anymore. I assume a good part of this was the greater amount of control that rigid control surfaces allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There appear to be some experimental supersonic aircraft that are using wing warping (or wing morphing) technology. What is the perceived advantage of this new generation of wing warping technology, what are barriers to its adoption, and how practicable is it for it to trickle down to general aviation?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastActivityDate="2016-05-19T00:46:59.693" Title="Are there any contemporary advantages in favor of wing warping?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11327" PostTypeId="1" AcceptedAnswerId="11328" CreationDate="2014-12-23T03:39:36.837" Score="9" ViewCount="1153" Body="&lt;p&gt;I've started flying again, and some of the things/places I fly are more interested in time in type than my old paper log shows. I'm considering going to some form of electronic logging (currently for Android and/or Linux but likely moving to iPad next year for EFB compatibility). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question: When I start up with a new program, do I merely summarize my flight experience and ignore the tail number and a/c type? I've flown a few different birds in my time, and trying to go back through 3 logs and setting everything correctly would be a royal pain.&lt;/p&gt;&#xA;" OwnerUserId="5602" LastEditorUserId="572" LastEditDate="2015-02-25T07:31:53.737" LastActivityDate="2019-03-19T21:08:47.657" Title="Are there any best practices for transitioning from paper logbooks to electronic logbooks?" Tags="&lt;faa&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11328" PostTypeId="2" ParentId="11327" CreationDate="2014-12-23T03:52:53.067" Score="6" Body="&lt;p&gt;Logbooks are an interesting blend of personal and professional recordkeeping.  The FAA doesn't really make a big deal about what method you use to log your flight time, just as long as you log all flight time which you're going to later use to justify currency or a new certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;This means that you can do whatever works best for you&lt;/strong&gt;, as long as you &lt;em&gt;(and your future employers)&lt;/em&gt; are happy with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I transitioned to &lt;a href=&quot;http://www.safelogweb.com/&quot;&gt;Safelog&lt;/a&gt;, I decided to spend a few weeks worth of evenings and just enter everything, line by line.  I did this because I had a lot of spare time, and because from now on I've got a pristine digital copy of everything, which is a nice feeling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this is certainly not necessary, and there is no reason why you couldn't summarize your totals with one or a few line items.  In fact, &lt;strong&gt;Safelog provides a function to do exactly that&lt;/strong&gt;: you create a pseudo-aircraft type which is defined as &quot;summarizes several aircraft&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get as coarse (1,302 hours in &lt;em&gt;airplanes&lt;/em&gt;) or as fine &lt;em&gt;(389 hours in blue C-172M's with the funny starter that sounds like you just dropped a shot glass in a garbage disposal)&lt;/em&gt; as you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say that whatever you choose to do, just be sure that you enter it using a format which will be compatible when you switch from Android to iPad.  It's bad enough to do it once, why put yourself through the hassle of doing it twice?&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2014-12-23T03:52:53.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11330" PostTypeId="1" CreationDate="2014-12-23T05:47:16.583" Score="11" ViewCount="2599" Body="&lt;p&gt;I don't understand exactly how the Wright brothers handled takeoff with the first gliders and powered plane. I know it has something to do with an elevated rail track. Also, if the flying position was head first, body parallel to the ground, how did they land without injury?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seperate question: for the initial glider flights, did they start at a high elevation and simply glide to the ground, or was there any method of increasing altitude during flight?&lt;/p&gt;&#xA;" OwnerUserId="5576" LastEditorUserId="97" LastEditDate="2014-12-23T08:01:41.007" LastActivityDate="2020-09-16T18:03:00.583" Title="How did the Wright plane takeoff/land?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11331" PostTypeId="2" ParentId="11330" CreationDate="2014-12-23T06:19:53.933" Score="9" Body="&lt;p&gt;As you said, they used a monorail for launches. The aircraft was pulled forward by a pulley which was connected to a weight which hung from a derrick. First the weight had to be pulled up, the pulley was run to the tip of the rail and back to the Flyer, and once the engine was running and the pilot in place, a helper released the weight and the pulley pulled the aircraft forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eo4fn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pictures here are taken from &lt;a href=&quot;http://www.thewrightbrothers.org/1904.html&quot; rel=&quot;noreferrer&quot;&gt;this site&lt;/a&gt;; I recommend it for further reading!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a picture of the rail, note the uptick at the end which gave the airplane a gentle push upwards, similar to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_deck#Ski-jump_ramp&quot; rel=&quot;noreferrer&quot;&gt;ski jump technique of British aircraft carriers&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DRhnJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For landing the Flyer used two skids. Depending on the ground, this could mean a gentle slide to standstill. Rougher landings would mean bruises for the pilot, like the ones suffered by Orville on August 23, 1904. But in most cases of a rough landing, the elevator assembly absorbed most of the impact energy. Elevator repairs were quite frequent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know less about the glider launching technique. Most glider tests were done with an unmanned glider held by strings into the wind. Glider flights would be downhill; thermalling was discovered much later (in 1913). However, even Otto Lilienthal already mentioned the uplifting effect of gusts, but neither he nor the Wright Brothers could circle tightly enough to stay inside a thermal.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-23T10:04:36.123" LastActivityDate="2014-12-23T10:04:36.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11332" PostTypeId="1" AcceptedAnswerId="11343" CreationDate="2014-12-23T06:52:11.853" Score="64" ViewCount="35114" Body="&lt;p&gt;The Boeing VC-25A (&quot;Air Force One&quot;) is a heavily modified 747-200. The two current airframes (SAM 28000 and 29000) were put into duty in 1990 and are slated to be replaced in 2017, although I suspect that latter date is optimistic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These two 747-200s are among the last remaining 747-200s in service. I suspect that they are the best-maintained 747-200s in the world and they have considerable sunk costs in their custom rigging, but even when the aircraft were put in service in 1990 their model had already been replaced by the 747-300 (1982) and 747-400 (1989).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why hasn't the VC-25A been replaced to keep up with the times? A 747-400 airframe is lighter, faster, and bigger (let alone a 747-8). These would all seem to be suitable features for what is most probably the most important aircraft in the USAF fleet. Is there some attribute of the 747-200 that makes it particularly well-suited for this role despite its obsolescence in the market?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="5653" LastEditDate="2014-12-29T22:42:53.110" LastActivityDate="2016-07-29T09:49:06.083" Title="Why does the US President fly in an obsolete 747-200?" Tags="&lt;military&gt;&lt;boeing-747&gt;&lt;us-air-force&gt;" AnswerCount="9" CommentCount="15" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11333" PostTypeId="2" ParentId="382" CreationDate="2014-12-23T09:48:15.450" Score="7" Body="&lt;p&gt;The Director General of Civil Aviation has published &lt;a href=&quot;http://dgca.nic.in/public_notice/PN_UAS.pdf&quot; rel=&quot;nofollow&quot;&gt;this public notice&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;GOVERNMENT OF INDIA OFFICE OF THE DIRECTOR GENERAL OF CIVIL AVIATION&#xA;  OPPOSITE SAFDARJUNG AIRPORT, NEW DELHI – 110 003 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PUBLIC NOTICE   File No. 05-13/2014-AED Dated: 7th October, 2014 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Subject: Use of Unmanned Aerial Vehicle (UAV)/ Unmanned Aircraft&#xA;  Systems   (UAS) for Civil Applications &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Of late, lots of interests are being shown for civil use (both&#xA;  commercial and recreational) of UAS in the country. International&#xA;  Civil Aviation Organization (ICAO) is yet to publish Standards And&#xA;  Recommended Practices (SARPs), as far as certification and operation&#xA;  of civil use of UAS is concerned. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;UAS has potential for large number of civil applications. However, its&#xA;  use besides being a safety issue, also poses security threat. The&#xA;  Airspace over cities in India has high density of manned aircraft&#xA;  traffic. Due to lack of regulation, operating procedures/ standards&#xA;  and uncertainty of the technology, UAS poses threat for air collisions&#xA;  and accidents.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The civil operation of UAS will require approval from the Air&#xA;  Navigation Service provider, defence, Ministry of Home Affairs, and&#xA;  other concerned security agencies, besides the DGCA. DGCA is in the&#xA;  process of formulating the regulations (and globally harmonize those)&#xA;  for certification &amp;amp; operation for use of UAS in the Indian Civil&#xA;  Airspace. Till such regulations are issued, no non government agency,&#xA;  organization, or an individual will launch a UAS in Indian Civil&#xA;  Airspace for any purpose whatsoever. The above is for strict&#xA;  compliance. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Director General of Civil Aviation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="5603" LastEditorUserId="1581" LastEditDate="2015-01-13T08:13:08.230" LastActivityDate="2015-01-13T08:13:08.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11334" PostTypeId="2" ParentId="11332" CreationDate="2014-12-23T10:37:34.743" Score="42" Body="&lt;p&gt;Commercial aircraft are designed for a service life of about 25 to 30 years. The 747-200 is no exception. The VC-25A entered into service in 1990, so it has operated now for almost 25 year. The number of flights will be low compared to aircraft in commercial service, so the aircraft is not worn out at all. Replacing it with a new aircraft as soon as a new model is available on the market is wasting taxpayers' money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In commercial service the Boeing 747-200 is too costly to operate these days. With a flight deck crew of three and four fuel-thirsty engines it is hard to compete with aircraft like the Boeing 777. But given the few flight hours that the VC-25A's make and the enormous investment needed to build a replacement aircraft the higher operating costs are acceptable.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On 28 January 2015, the &lt;a href=&quot;http://www.af.mil/News/ArticleDisplay/tabid/223/Article/562748/af-identifies-boeing-747-8-platform-for-next-air-force-one.aspx&quot;&gt;US Air Force announced&lt;/a&gt; that the VC-25A's will be replaced by an aircraft based on the Boeing 747-8. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“The current fleet of VC-25 presidential aircraft has performed&#xA;  exceptionally well, a testament to the Airmen who support, maintain&#xA;  and fly the aircraft,” Secretary of the Air Force Deborah Lee James&#xA;  said. “Yet, it is time to upgrade. Parts obsolescence, diminishing&#xA;  manufacturing sources and increased down times for maintenance are&#xA;  existing challenges that will increase until a new aircraft is&#xA;  fielded.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-30T09:44:08.503" LastActivityDate="2015-01-30T09:44:08.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11335" PostTypeId="2" ParentId="11326" CreationDate="2014-12-23T11:42:57.140" Score="7" Body="&lt;p&gt;All wings warp. The extent of warping is one restriction which limits the fast side of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_envelope&quot;&gt;flight envelope&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once aircraft designers realized that thick wings have less drag, they tried to build their wings as stiff as possible. Stiff wings allow to use airfoils with rear loading, will have &lt;a href=&quot;https://www.youtube.com/watch?v=kQI3AWpTWhM&quot;&gt;higher flutter frequencies&lt;/a&gt; and keep their shape even when operating at high dynamic pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the center of pressure moves chordwise on cambered airfoils depending on the angle of attack, any cambered wing will suffer from pitching moments around its axis of elasticity. This moment will &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroelasticity&quot;&gt;twist the wing&lt;/a&gt; and change the incidence of the outer wing sections. A stiff wing will suffer less twisting and stay closer to its ideal aerodynamic shape. Add an aileron, and another twisting moment is added on top. Now the wing twists opposite to the aileron deflection! This can become so bad that most of the aileron's effectiveness is lost as the wing is warped in a way which counteracts the lift change of the aileron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_X-53_Active_Aeroelastic_Wing&quot;&gt;X-53 research aircraft&lt;/a&gt; uses this effect with an array of leading and trailing edge devices to actively warp the wing in the desired direction. Using computer-controlled deflections of small but very effective control surfaces, it creates a desired deformation of the wing for roll control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be compared to the effect a &lt;a href=&quot;http://en.wikipedia.org/wiki/Servo_tab&quot;&gt;Flettner tab&lt;/a&gt; has on an aileron. The Flettner tab is a small control surface at the trailing edge of a larger control surface and is deflected by the pilot such that it moves the big control surface in opposite direction. It slightly reduces the effectiveness of the big control surface, but needs only a fraction of the stick force, thus helping to manually control big aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the active wing warping of the X-53 depends on the proper functioning of the FCS and an array of movable devices, each with its own failure mode, I would hesitate to see this as a clear advantage. It allows, however, to control the aircraft at high dynamic pressure with minimal drag penalties.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-23T11:48:11.683" LastActivityDate="2014-12-23T11:48:11.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11336" PostTypeId="1" AcceptedAnswerId="11337" CreationDate="2014-12-23T11:54:28.103" Score="23" ViewCount="11006" Body="&lt;p&gt;Reading about the 787 it says it has &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an active &lt;em&gt;gust alleviation system&lt;/em&gt; similar to the system used on the&#xA;  B-2 bomber. [&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot;&gt;1&lt;/a&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The gust alleviation patent says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The gust alleviation system picks off the stick displacement signal&#xA;  and the aircraft normal acceleration sensor signal and processes this&#xA;  information. The outputs of the gust alleviation system are added back&#xA;  respectively to the existing flap command signal and the aircraft's&#xA;  original stability augmentation loop. [&lt;a href=&quot;http://www.freepatentsonline.com/4905934.html&quot;&gt;2&lt;/a&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a layman I am not sure I fully understand this, so my question is, what is the gust alleviation system?&lt;/p&gt;&#xA;" OwnerUserId="2448" LastActivityDate="2020-07-08T07:44:04.990" Title="What is a gust alleviation system?" Tags="&lt;aircraft-systems&gt;&lt;boeing-787&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11337" PostTypeId="2" ParentId="11336" CreationDate="2014-12-23T12:32:13.397" Score="24" Body="&lt;p&gt;A gust alleviation system is a control system fitted to some Fly-by-wire (FBW) aircraft that reduces the effect of gust loads on the aircraft by deflecting control surfaces such as ailerons, rudder and elevators.&lt;/p&gt;&#xA;&lt;p&gt;The system works by measuring the upward acceleration of the aircraft and comparing that with the acceleration commanded by the (auto)pilot. A feedback loop adds a correction signal to the signals controlling the deflection of the control surfaces in order to counteract the accelerations cause by wind gusts.&lt;/p&gt;&#xA;&lt;p&gt;In its simplest form the accelerations are sensed near the center of gravity of the aircraft. More advanced implementations work with multiple sensors in the body and in the wings. These gust alleviation systems do not only attempt to annul the effect of the gusts on the aircraft's normal (upward) acceleration, they also reduce the wing bending moments. This in turn reduces metal fatigue.&lt;/p&gt;&#xA;&lt;p&gt;In the A380 the load alleviation system is nicknamed &amp;quot;valse des aileron&amp;quot; (Waltz of the Ailerons) because of the dancing movements of the aileron:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=YqLyKwx8KNE&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ABJel.png&quot; alt=&quot;&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="49973" LastEditDate="2020-07-08T07:44:04.990" LastActivityDate="2020-07-08T07:44:04.990" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="11338" PostTypeId="2" ParentId="11336" CreationDate="2014-12-23T12:33:42.753" Score="10" Body="&lt;p&gt;Gusts change the dynamic pressure of the airflow over the wing. Vertical gusts even change the angle of attack. Both will change the lift the wing creates, and especially vertical gusts add stresses for the structure and discomfort for the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By changing aileron deflection, the wing's lift can also be manipulated. If the aileron deflection is just enough to compensate the added aerodynamic load due to a gust, both the wing and the passengers will benefit. By coupling the readings of &lt;a href=&quot;http://en.wikipedia.org/wiki/Accelerometer&quot;&gt;accelerometers&lt;/a&gt; near the wing tip, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot;&gt;FCS&lt;/a&gt; can adjust the aileron deflection and ideally keep the wing bending constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the ailerons are at the outer 30% of span, they have a big influence on the root bending moment, but affect only a small part of the lift the wing can create. Therefore, while the bending moment can be nicely held constant, the lift will still vary, but less than without gust alleviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The part referring to the stick in the quoted patent refers to a mechanical control system with a naturally stable aircraft. If an aircraft with such a control system flies into a vertical gust, it will pitch up or down, which in turn will shift the equilibrium stick position. However, this will happen with some delay (the fuselage tip will &quot;see&quot; the gust first, and the tail will be affected by it some tenths of a second later), so the stick movement is a poor source for a feedback loop. I wonder why the patent mentions it - maybe the patentee wanted to cover all input sources.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2014-12-23T17:09:29.527" LastActivityDate="2014-12-23T17:09:29.527" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11340" PostTypeId="1" CreationDate="2014-12-23T14:11:15.737" Score="14" ViewCount="3199" Body="&lt;p&gt;Why are we not using the GMT time standard in an aircraft? Why is only UTC the standard on-board?&lt;/p&gt;&#xA;" OwnerUserId="5543" LastEditorUserId="595" LastEditDate="2016-03-22T06:31:11.597" LastActivityDate="2016-03-22T06:31:11.597" Title="Is there any reason to use only UTC standard time in aircraft and not GMT?" Tags="&lt;aircraft-design&gt;&lt;pilots&gt;&lt;clock&gt;&lt;time&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11341" PostTypeId="2" ParentId="11340" CreationDate="2014-12-23T14:15:26.233" Score="22" Body="&lt;h2&gt;UTC is in principle the same as GMT.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;But for accurate applications there is a difference:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Saying &quot;GMT&quot; often implies either UTC or UT1 when used within informal or casual contexts. In technical contexts, usage of &quot;GMT&quot; is avoided; the unambiguous terminology &quot;UTC&quot; or &quot;UT1&quot; is preferred. &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;UTC&lt;/strong&gt;: Is defined by atomic clock with corrections for leap seconds added manually.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;UT1&lt;/strong&gt;: Is defined by the Earth's rotation, hence is more susceptible for change and less easy to calculate than an atomic clock.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However the difference between the two is less than one second. It might matter for your $8000 \frac{\text{m}}{\text{s}}$ satellite or for your $300 \frac{\text{m}}{\text{s}}$ aircraft, but otherwise your can consider them equal for informal applications.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="959" LastEditDate="2014-12-24T14:03:56.200" LastActivityDate="2014-12-24T14:03:56.200" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11342" PostTypeId="2" ParentId="11340" CreationDate="2014-12-23T14:36:33.827" Score="10" Body="&lt;p&gt;GMT (Greenwich Mean Time) is a time zone, observed by the UK and Portugal in winter and by Iceland and a number of African countries. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;UTC (Coordinated Universal Time) is a time standard, defined by an atomic clock. It is kept synchronous with the solar time by adding (or removing) leap seconds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the GMT time zone, the time is equal to UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before UTC was defined, GMT was the international reference time, called 'Zulu-time'.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-23T14:42:08.310" LastActivityDate="2014-12-23T14:42:08.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11343" PostTypeId="2" ParentId="11332" CreationDate="2014-12-23T16:19:22.787" Score="53" Body="&lt;p&gt;The 747-200 derivatives used for transporting the President of the United States are VC-25's operated and maintained by the United States Air Force. The US Air Force tends to keep planes for a long time, as they still operate 707 and B-52 aircraft twice as old as these 747's. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_E-4&quot;&gt;E-4 aircraft&lt;/a&gt;, also based on the 747-200, have been in service for 40 years. The reasons for keeping the VC-25 aircraft flying are similar to these other examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of work went into the VC-25 aircraft. They have been modified to add aerial refueling capability, defensive mechanisms, and include extensive additional electronic equipment for communications. Installing the special interiors was also a major task. As with a bomber or AWACS, there is a large initial investment in development to design the systems and build the aircraft. Upgrading components and providing proper maintenance allows these aircraft to perform their missions long after their entry into service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another difference is the engines. The 747-200B model has GE CF6-50E2 engines producing 52,500 lbf thrust each. The VC-25 aircraft have newer CF6-80C2B1 engines producing 56,700 lbf thrust each, which is the same engine as the 747-300. Newer engines go a long way towards improved performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As DeltaLima notes, these aircraft do not spend nearly as much time in the air as commercial aircraft. Yet there are many commercial aircraft in service with similar or greater age, including some 747-200 aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2014-12-23T22:58:48.050" LastActivityDate="2014-12-23T22:58:48.050" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11344" PostTypeId="5" CreationDate="2014-12-23T16:55:52.210" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_150&quot; rel=&quot;nofollow&quot;&gt;Cessna 150&lt;/a&gt; is a two-seat, high-wing, tricycle gear aircraft manufactured by Cessna from 1957 to 1977. It is commonly used as a training aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_150&quot; rel=&quot;nofollow&quot;&gt;Cessna 150&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-23T16:55:52.210" LastActivityDate="2014-12-23T16:55:52.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11345" PostTypeId="4" CreationDate="2014-12-23T16:55:52.210" Score="0" Body="The Cessna 150 is a two-seat light aircraft, often used for flight training" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-23T16:55:52.210" LastActivityDate="2014-12-23T16:55:52.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11346" PostTypeId="2" ParentId="11332" CreationDate="2014-12-23T17:01:47.577" Score="13" Body="&lt;p&gt;A lot of work went into configuring a 747-200 model into an airplane which can be called &quot;Air Force One&quot; (remember it is just a call sign):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a cabin with a kitchen and sound-proof conference rooms&lt;/li&gt;&#xA;&lt;li&gt;Secure communication to satellites and military controls&lt;/li&gt;&#xA;&lt;li&gt;Flares and air-refueling probes&lt;/li&gt;&#xA;&lt;li&gt;etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, it is just a &lt;strong&gt;&lt;em&gt;massive&lt;/em&gt;&lt;/strong&gt; amount of work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not like you have to replace everything once it is obsolete. For example, a typical consumer computer or smartphone can last quite a few years.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A computer / smartphone:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;faster, no new essential functionality, brand new&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;An existing computer / smartphone:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;slightly slower, 100% operational, 9 months old&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;No way I will spend significant time and money just for a &lt;em&gt;slightly&lt;/em&gt; faster performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The VC-25 aircrafts are heavily customized for their task. Their components are well maintained. In aircraft lift cycles, 20 years is not short, but not long either. Surely the aircrafts will age over time, at one point it will be too expensive to maintain them than to order a new one. But such time has yet to come.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2014-12-24T02:11:54.537" LastActivityDate="2014-12-24T02:11:54.537" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11347" PostTypeId="2" ParentId="11320" CreationDate="2014-12-23T21:20:40.207" Score="10" Body="&lt;p&gt;Airships have a center of lift well above their center of mass, since engines and the gondola are mounted at the bottom. This gives them a strong static pitch stability: They will try to assume an attitude where the center of mass is right below the center of lift. Normally, the airship will be carefully trimmed to ensure that the hull is level at this attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cYaIn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During flight both the mass and the lift will not stay constant: Sun might shine on the hull, heating and expanding the gas inside and increasing lift, the hull might be wetted by rain and become heavier, or fuel burn will lighten the ship. To stay at the desired altitude, the airship can compensate for any imbalance by creating dynamic lift. By pitching the hull up or down, up to 10% of the needed lift can be added or subtracted this way. Note that this will not only create aerodynamic lift, but it will also point engine thrust slightly up- or downwards, which will add to the lift change. If the ship is fast enough, a negative deflection of the horizontal tail surface or a shifting of masses backward will increase lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hroWR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low speed, however, both thrust and aerodynamic lift are much lower, but both mass and static lift are unchanged. Now the ship needs considerably more elevator deflection for the same pitch attitude change, but aerodynamic lift and engine thrust will be a lot less. The downforce at the horizontal tail must still be equal to that at high speed, since the static moment has not changed, and the lower dynamic pressure at low speed is compensated by deflecting the elevator by a  bigger angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below the critical speed, the elevator downforce will become dominant, and pitching the ship up will &lt;strong&gt;decrease&lt;/strong&gt; total lift. The critical speed is characterized as the speed at which attitude changes will not result in lift changes, and when crossing this speed, the elevator effect on lift reverses. For this reason some books use the term &quot;reversal speed&quot; for the critical speed. No airship captain wants to cruise at this speed, since he will be bereft of means to change lift quickly!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This effect can create a dangerous situation if a heavy ship comes in for landing. In cruise, the missing static lift could easily be compensated by raising the nose, but now the ship has to decelerate. It will start to pick up sink speed, and raising the elevator will make matters worse. The only way to avoid a crash in this situation is the application of reverse thrust combined with a positive elevator deflection which lifts up the tail. Proper timing is of the essence: The ship must touch down at the desired location just when the reverse thrust has stopped both the vertical and the horizontal speed. This requires a trained crew and a skilled commander. If the propellers cannot run in reverse, this situation must be avoided at all cost!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The critical speed is higher the blunter the airship is. The slender Zeppelins of the first World War had a fairly low critical speed (maybe 8 m/s), but the &lt;a href=&quot;http://www.aerospace-technology.com/projects/cargolifter/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cargolifter's&lt;/a&gt; critical speed was around 20 m/s. During the design phase the required power had to be increased by 40% to raise the cruise speed by a sufficient margin above the critical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the vertical and the horizontal tail surfaces of airships are much smaller than what would be required for natural stability, and they &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1924/naca-report-184.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;typically were just big enough to keep the ship under control&lt;/a&gt;. Aerodynamic lift is mostly created at the forward part of the hull, and lifting the nose will increase the pitch-up moment. The same goes for the sideforce: In both axes the helmsman needs to constantly correct the control surface deflection to keep the ship at the desired attitude and heading. Below the critical speed, the aerodynamic forces and the pitch-up due to the low location of the propellers will not be sufficient to overcome the static stability, so pitch excursions will be limited. Above the critical speed the aerodynamic instability will become dominant and the helmsman needs to be alert and responsive.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-12T22:54:16.663" LastActivityDate="2015-03-12T22:54:16.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11348" PostTypeId="2" ParentId="11237" CreationDate="2014-12-23T22:35:42.120" Score="4" Body="&lt;p&gt;Another very important accident that can occur is what I know as the Kavalierstart. It occurs on winch launches with some airplanes when the pilot is not pushing the joystick all the way forward. The airplane gaining speed really fast will pitch up and as it is going up with a very steep angle, the lift will actually pull in the opposite direction of where the winch rope is coming from. Due to the excessive load the rope will break, and as the hook is before the CG, the missing force of the rope will cause the glider to continue pitching up bringing it into a upside down attitude (as it is already flying up pretty much vertically). Without the rope pulling the glider it will almost immediately lose its airspeed and drop down. There is no way over recovering this and it usually ends up in killing everyone on board. &lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="5592" LastEditDate="2014-12-24T02:01:26.990" LastActivityDate="2014-12-24T02:01:26.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11349" PostTypeId="2" ParentId="11332" CreationDate="2014-12-23T22:35:47.490" Score="4" Body="&lt;p&gt;The 747-200 is &lt;em&gt;commercially&lt;/em&gt; obsolete: in order to make a profit, an airline operating one would have to charge too much money to be competitive against someone with a 777 or a 747-800. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Air Force isn't making money off of its VC-25 fleet.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2014-12-23T22:35:47.490" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11350" PostTypeId="1" AcceptedAnswerId="11351" CreationDate="2014-12-23T23:25:53.020" Score="11" ViewCount="303" Body="&lt;p&gt;I flew today to Salinas, CA and had a little trouble reaching Salinas tower (KSNS). The current VFR sectional shows the tower frequency as 119.4. However, apparently the frequency changed to 119.525 on June 2014 (according to &lt;a href=&quot;http://www.montereybay99s.org/newsletter/July2014issue.pdf&quot;&gt;http://www.montereybay99s.org/newsletter/July2014issue.pdf&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current VFR sectional was issued in August 2014, after the frequency change. I'm wondering why (a) the frequency is incorrectly printed on the current VFR sectional, and (b) if it's an error why there is no NOTAM about it.&lt;/p&gt;&#xA;" OwnerUserId="5615" LastEditorUserId="19" LastEditDate="2017-04-19T15:00:58.343" LastActivityDate="2017-04-19T15:00:58.343" Title="Why are there out-of-date tower frequencies on the VFR sectional chart, without a NOTAM?" Tags="&lt;visual-flight-rules&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11351" PostTypeId="2" ParentId="11350" CreationDate="2014-12-23T23:41:14.603" Score="14" Body="&lt;p&gt;It's not a printing error. FAA sectional charts are updated only once every six months. In order to to reduce the number of NOTAMs due to sectional changes (which can number in the hundreds between cycles), the FAA provides a section in the &lt;strong&gt;Airport Facility Directory&lt;/strong&gt; (AFD), titled &quot;Aeronautical Chart Bulletin&quot; that identifies changes that have occurred since a chart's publication. Pilots should check this section on each AFD update for changes on their intended route of flight. Once the change is posted in the AFD, the respective NOTAM is taken down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an image of the applicable AFD page for Salinas, as of the date of this answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AsUns.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2014-12-23T23:58:26.537" LastActivityDate="2014-12-23T23:58:26.537" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11353" PostTypeId="1" AcceptedAnswerId="11354" CreationDate="2014-12-24T02:10:21.670" Score="15" ViewCount="2967" Body="&lt;p&gt;Light sport aircraft may have a &lt;a href=&quot;https://www.eaa.org/~/media/files/eaa/aviationinterests/lsa/sport-pilot-rule.pdf&quot; rel=&quot;noreferrer&quot;&gt;max airspeed in level flight at MCP of 120kts&lt;/a&gt;. I have heard that there are some light sport aircraft that have had their wings clipped in order to have a lower cruise speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why do they clip the wings to reduce the cruise speed? Wouldn't that require a higher speed as less lift is produced at the same speed with less wing area? &#xA;Also, thinking about gliders having a big wing span and fighter jets having a short wing span I can not see why you would clip the wings? What am I missing? &lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="62" LastEditDate="2019-10-16T02:16:34.680" LastActivityDate="2019-10-16T02:16:34.680" Title="Do some light sport aircraft have clipped wings to lower their cruise speed?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;wing&gt;&lt;light-sport-aircraft&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="11354" PostTypeId="2" ParentId="11353" CreationDate="2014-12-24T07:57:52.230" Score="18" Body="&lt;p&gt;You must have heard wrong. Clipping wings is done to reach higher maximum speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You mention light sport aircraft, so I assume they have propellers driven by piston engines. This means their power output is constant over speed and the thrust is inverse with speed. To calculate their &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;optimum cruise speed&lt;/a&gt;, you can use the venerable &lt;a href=&quot;http://www.southampton.ac.uk/~jps7/Aircraft%20Design%20Resources/aerodynamics/Breuget%20Equation.htm&quot; rel=&quot;noreferrer&quot;&gt;Breguet equation&lt;/a&gt; which shows that the aircraft has to fly at its optimum L/D for maximum range. At this speed, induced drag equals zero-lift drag, and span helps to cut down the former. Clipping the wing will shift the optimum cruise speed up, not down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With clipped wings the aircraft has less surface area, which will reduce zero-lift drag. This is the drag component which determines maximum speed. Induced drag at a given speed will go up, but it is insignificant at maximum speed, so the aircraft will be able to fly slightly faster.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-04-08T06:58:47.820" LastActivityDate="2018-04-08T06:58:47.820" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11355" PostTypeId="2" ParentId="11340" CreationDate="2014-12-24T09:33:49.653" Score="4" Body="&lt;p&gt;Because the earth's orbit varies, the value of a GMT second varies. Technological development, especially the advent of computers required the use of a constant second, not a variable second. GPS, for example, requires the use of a constant second, as do all sorts of aviation related equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The history of developing a non-varying standard second is involved to say the least, but in the end the time it takes for a Cesium-133 atom to oscillate 9,192,631,770 times was chosen as the definition of a UTC second. Atomic clocks around the world are coordinated to keep UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usage of astronomically determined time as the world's standard for technical purposes stopped on January 1, 1972 (as I remember) except for the purpose of updating UTC. Whenever UTC differs from UT1 (the current astronomically determined time) by 0.9 seconds, a leap second is applied to UTC. Thus GMT and UT1 never differ by more than one second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The world's time zones are all assigned a letter. U is the letter assigned to my time zone (UTC-8, in Oregon), Z to the time zone the center of which in the prime meridian at Greenwich (UTC-0).&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2014-12-24T18:22:32.267" LastActivityDate="2014-12-24T18:22:32.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11356" PostTypeId="1" AcceptedAnswerId="11358" CreationDate="2014-12-24T10:47:21.153" Score="7" ViewCount="4812" Body="&lt;p&gt;Often flying I have this fear, that something will snap, and the plane will start plunging to the ground in a spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, once a passenger aircraft (e.g. an A320) goes into a spin, can the pilots recover it, stabilize it and make it glide, or is it too late?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/q/753/19&quot;&gt;similar question&lt;/a&gt; was asked before, but I am looking specifically for answers regarding large passenger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-04-03T13:43:00.173" Title="If a commercial airliner enters into a spin at high altitude, is it possible to recover?" Tags="&lt;spins&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11358" PostTypeId="2" ParentId="11356" CreationDate="2014-12-24T12:20:25.207" Score="8" Body="&lt;p&gt;As DeltaLima said, it is kind of hard answering your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After looking at the &lt;a href=&quot;https://aviation.stackexchange.com/questions/753/is-spin-recovery-possible-in-an-airliner&quot;&gt;question he linked&lt;/a&gt; you might have found the answer already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me try to answer your specific question though:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming an airliner, let's say the A320, for some reason got into a spin, can it be recovered? The general answer would be yes!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some things to consider though:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requires all single-engine normal category aircraft to demonstrate spin recovery in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/78909ED5A6DBEB9485256687006D0568?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 23.221(2)&lt;/a&gt;.&#xA;It depends a lot on the center of gravity of the airplane whether it is recoverable from a  spin or not. If the center of gravity is too far aft, it will not be recoverable from a spin. Gliders, being light, have an easy shiftable CG, and there is some that don't enter spins at all or need extra weights in the back in order to make them spinnable! Airliners are not required to do so as they are not as likely to get into a spin in the first place!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The structure of an airliner is designed for air flowing over it, not for being in a spin! Centrifugal forces will be applied to the structure due to angular acceleration. Also, spins by airliner would be a lot faster then by little aircraft and more forces would be applied to the frame. If the recovery from the spin is made too fast or abrupt, it can overstress the airplane as well!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All Airbus I know are fly-by-wire, and Airbus is well known for its computer based controls. Most airliners have a lot of systems, which prevent them from even getting into a stall. There a incidents where these systems failed and it went back to the pilot doing the right thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a spin always always always requires a stall first, and pilots are trained to avoid stalls in the first place, it is very unlikely for an airliner to enter a spin, having the pilot and various systems working against entering a stall!&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2014-12-25T18:34:18.553" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11359" PostTypeId="2" ParentId="8163" CreationDate="2014-12-24T14:42:10.643" Score="7" Body="&lt;p&gt;The Cessna 208 is a bit of a confusing model when it comes to seating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Short version&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under US legislation, the aircraft may have up to 11 seats and can carry 9 passengers and 2 pilots. Other countries did recertify the aircraft to have up to 14 seats. By doing so they adopt the FAA certification based on part 23 and add text to waive the 9 passenger limitation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Long version&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally the type was approved by the FAA in October 1984 under FAR 23 (up to amendment 28) and given FAA Type certificate number &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_Library/rgMakeModel.nsf/0/76dc1935f5c5059686257839005aeedd/$FILE/A37CE%20Rev%2016.pdf&quot;&gt;A37CE&lt;/a&gt;. The aircraft is certified as 11 Place Closed Land Monoplane (PCLM) and later as 11 Place Closed Sea Monoplane (PCSM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1984 the applicability of &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/certification_basis/part23_summary/&quot;&gt;Part 23&lt;/a&gt; was described by 23.1 (since &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/DD3BD5D844708F3D85256687006B5C78?OpenDocument&quot;&gt;amendment 10&lt;/a&gt;) as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) This Part prescribes airworthiness standards for the issue of type&#xA;  certificates, and changes to those certificates, for small airplanes&#xA;  in the normal, utility, and acrobatic categories that have a passenger&#xA;  seating configuration, excluding pilot seats, of nine seats or less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So this is where the 9 passenger limitation originally comes from. This also implies that if you operate with only one pilot, one of the 11 seats must be unoccupied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until 1971 there was no mention of a 9 passengers limitation and since 1987 (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/CF1B59F8222D50C885256687006B5FAF?OpenDocument&quot;&gt;amendment 34&lt;/a&gt;) a new category of commuter planes is defined allowing for more than 9 passenger (up to 19 passengers) in propeller-driven, multiengine airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the Cessna 208 is a single engine aircraft, the commuter category cannot apply. As a result, when the aircraft is operating under the FAA type certificate, there is a limit of 9 passengers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft is registered and operated outside the USA, the FAA rules do not necessarily apply. Usually a country adopts the Type Certificate of the original certifying country, but changes can be made. This is exactly what happened with the Cessna 208. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the aircraft offers space for more seats and the maximum take-off weight allows for extra passengers, Cessna started to offer a 14 seat model for use outside the USA.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft with more than 11 seats, the flight manual has a &lt;a href=&quot;http://www.avcom.co.za/phpBB3/download/file.php?id=210752&amp;amp;sid=d069eec9750c7a18f9f3de44e4c72ab7&quot;&gt;supplement&lt;/a&gt; stating:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Limitations&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Utilization of the 13-place, 14-place and Utility seating options&#xA;  described in this supplement is limited only to nations where approval&#xA;  has been received. The United States does not authorize more than 11&#xA;  seats in the airplane. In the 11- seat configuration, the right front&#xA;  seat may be occupied by either a second crew member or a passenger,&#xA;  However, when the right front seat is occupied by a passenger, only&#xA;  eight seats in the aft cabin can be occupied.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Europe (EU)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/EASA-TCDS-A.226_(IM)_Cessna_Model_208-05-15032011.pdf&quot;&gt;EASA Type certificate&lt;/a&gt; allows the 11 seat model 208. It also mentions a 14 seat model 208&lt;strong&gt;B&lt;/strong&gt; being approved by the UK CAA. When EASA took over aircraft certification in Europe, the UK CAA approvement for 14 seats was adopted, but only for the 208B model. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In section 2.E (only for 208B):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A 14 seat place configuration was certified before 28 September 2003&#xA;  by CAA UK (see UK TCDS FA54) and subsequently adopt by EASA. Those&#xA;  aircraft have to be operated i.a.w. FAA approved AFM 1329-3- 13PHUK&#xA;  and AFM Supplement D1340-1-13UK or latest approved revision.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The original &lt;a href=&quot;https://www.caa.co.uk/docs/1419/srg_acp_fa54-04.pdf&quot;&gt;UK CAA approval&lt;/a&gt; included the text:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MAXIMUM OCCUPANTS/PASSENGERS: 14 occupants, including pilot. Refer to&#xA;  British Aeroplane Flight Manual&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Australia&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.casa.gov.au/wcmswr/_assets/main/casadata/cota/download/a123.pdf&quot;&gt;type certificate for the Cessna 208&lt;/a&gt; mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Australian registered Cessna 208 aircraft may be configured for&#xA;  greater than 9 passenger seats. The requirement of FAR 23 paragraph&#xA;  23.1, introduced by amendment 23-10, to limit the passenger seating configuration, excluding pilot seats, to nine seats or less is not&#xA;  applicable to Australian aeroplanes certificated under Section 101.22&#xA;  of Civil Aviation Orders.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://www.casa.gov.au/wcmswr/_assets/main/casadata/cota/download/a032.pdf&quot;&gt;type certificate for the Cessna 208B&lt;/a&gt; reference is given to the UK CAA approval for more than 11 seats.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;New Zealand&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;New Zealand &lt;a href=&quot;https://www.caa.govt.nz/aircraft/Type_Acceptance_Reps/Cessna_208_Series.pdf&quot;&gt;allows&lt;/a&gt; the 208 to be operated with 14 seats. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In New Zealand the Model 208 Caravan has been approved for operation&#xA;  in the fourteen seat configuration in accordance with the provisions&#xA;  of the Fourteen Place Seating Supplement to the Model 208 Pilot’s&#xA;  Operating handbook. (A similar Supplement is included in the Flight&#xA;  Manual for the 208B.) The 208 aircraft was “accepted on the basis of&#xA;  compliance with FAR23 excluding the wording of FAR 23.1(a); ‘that have&#xA;  a passenger seating configuration, excluding pilot seats, of nine&#xA;  seats or less’.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;South Africa&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The type certification document from New Zealand mentions that at the time of first approval (1985) Cessna stated: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Australia, UK, South Africa, Norway, Sweden, Kenya and Columbia had&#xA;  all accepted the Cessna 208 with more than nine passenger seats.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Interestingly in February 2014 the CAA of South Africa (SACAA) &lt;a href=&quot;http://www.caa.co.za/Airworthiness%20Important%20Notices%20%20Documents/Operation%20of%20C208%20Aircraft%20with%20a%20seating%20configuration%20in%20excess%20as%20stipulated%20in%20the%20type%20certificate.pdf&quot;&gt;denied that the 208 was ever approved for operation with more than 11 seats&lt;/a&gt; in South Africa. Operators using the Cessna 208 with more than 11 seats found themselves operating the aircraft illegally suddenly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quickly a Supplemental Type Certificate (STC) was &lt;a href=&quot;http://www.comairsa.co.za/News/post/14-seat-caravan-stc-approved&quot;&gt;approved in June 2014&lt;/a&gt; which allows operation with 14 seats again. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-25T09:54:41.667" LastActivityDate="2014-12-25T09:54:41.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11360" PostTypeId="1" CreationDate="2014-12-25T03:36:40.957" Score="8" ViewCount="280" Body="&lt;p&gt;I'm about to go to the United States and do some flying. I sorted out my FAA license conversion but I was wondering how to get aircraft renter's insurance. It seems that some schools / clubs require this, and it's not included in the hire contract.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I googled a bit but it's seems that all the policies are for US residents and annual contracts. I'm more interested in a month or so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anybody else who's had this problem? Any suggestions ?&lt;/p&gt;&#xA;" OwnerUserId="1957" LastEditorUserId="62" LastEditDate="2016-07-06T19:14:19.700" LastActivityDate="2016-07-06T19:14:19.700" Title="How can a foreign pilot get renter's insurance in the USA?" Tags="&lt;general-aviation&gt;&lt;usa&gt;&lt;renters-insurance&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11361" PostTypeId="2" ParentId="11332" CreationDate="2014-12-25T03:39:30.817" Score="4" Body="&lt;p&gt;One reason the 747 was chosen rather than wait for the 777, is that it had 4 engines (like the previous 707).  Newer planes tend to have 2 engines as it's more fuel efficent.  4 engines can be more reliable when in a hostile environment. &lt;/p&gt;&#xA;" OwnerUserId="5626" LastActivityDate="2014-12-25T03:39:30.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11363" PostTypeId="2" ParentId="11360" CreationDate="2014-12-25T15:11:35.160" Score="3" Body="&lt;p&gt;Most flight schools in the US have an easy policy for renting out their planes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You go there, you do a checkout flight on an airplane with one of their instructors, and you can go ahead and fly as much as you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The planes are then insured by the flight school, and you pay for the insurance by paying an hourly fee to the flight school. The checkout flight is necessary for the insurance, and is most of the time valid for 90 days. After that, another checkout flight might be required. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You, though, might not be included in that insurance. If something happens to you, the flight school's insurance will probably not cover the costs you might have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't want to advertise on here, but for if you are interested I can show you a nice flight school in Florida.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="5517" LastEditDate="2016-07-06T11:58:48.707" LastActivityDate="2016-07-06T11:58:48.707" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11365" PostTypeId="2" ParentId="10060" CreationDate="2014-12-25T20:17:05.170" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.favt.ru/favt_new/?q=dejatelnost/ajeroporty_i_ajerodromy/ceny_na_aviagsm&quot;&gt;Here&lt;/a&gt; is the data for Russian airports (unfortunately, in Russian).&lt;/p&gt;&#xA;" OwnerUserId="2421" LastActivityDate="2014-12-25T20:17:05.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11366" PostTypeId="1" AcceptedAnswerId="11386" CreationDate="2014-12-25T21:01:41.013" Score="9" ViewCount="1103" Body="&lt;p&gt;I recently became interested in becoming a commercial pilot after buying Flight Simulator X and a Saitek Yoke system. I'm still studying my GCSE's, and I am now debating between computer science and a career as a pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I currently don't have the money to get my private pilot license, and very much doubt that I'll have the money for commercial training in the future. Therefore, I am curious as to whether or not some universities offer both PPL and commercial flight training as part of an aviation degree program.&lt;/p&gt;&#xA;" OwnerUserId="5631" LastEditorUserId="69" LastEditDate="2014-12-29T01:25:35.847" LastActivityDate="2016-05-05T08:35:32.953" Title="Do any UK universities include PPL/Commercial flight training as part of an aviation degree?" Tags="&lt;flight-training&gt;&lt;uk&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11367" PostTypeId="2" ParentId="11356" CreationDate="2014-12-25T21:03:18.680" Score="11" Body="&lt;h2&gt;How to stabilize a spinning aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Stabilizing a spinning aircraft is fairly easy. If the center of gravity is not too far forward, the rudder is deflected in spin direction and the elevator fully up (adjusting the horizontal tail trim helps, too), the spin will continue until the aircraft hits the ground. In some cases, the spin might oscillate between two stable modes, and the aircraft will continuously pitch up and down between them. An airliner with its high wing loading will loose a couple of hundred meters per turn in a spin, but will not accelerate once the spin has fully developed. Increasing air density on the way down will actually decrease the rate of descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I guess you wanted to ask something entirely different.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Ending a spin&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin&quot;&gt;Ending the spin is equally easy&lt;/a&gt; and is performed by the opposite commands which stabilize the spin. Proving that the aircraft will easily come out of a spin is actually part of certification requirements. The stable rate of descent gives the pilots ample time to end the spin, and even if the engines have failed, &lt;a href=&quot;http://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;emergency systems&lt;/a&gt; will ensure that the pilots can control the aircraft. The risk that an otherwise normal flight will end in an unrecoverable spin is practically zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would actually prefer that the airplane enters a spin. If the center of gravity is in the forward part of the allowed range, it is more likely that it will enter a &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_dynamic_modes#Spiraling&quot; rel=&quot;nofollow noreferrer&quot;&gt;spiral dive&lt;/a&gt; after stalling. Now the pilots need to react quickly and with measure, because drag is much lower in a spiral dive than in a spin, and the resulting higher speed poses a real danger. For that reason the flight control system in the type of aircraft you mentioned, the A-320, will &lt;a href=&quot;https://aviation.stackexchange.com/questions/149/what-are-the-main-differences-piloting-boeing-vs-airbus-aircraft/2698#2698&quot;&gt;prevent the aircraft from entering a spiral dive&lt;/a&gt; in the first place.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What if something snaps?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;So far, we have assumed that all systems work. What if something snaps? The surprising answer is: Mostly nothing. A fundamental design principle for aircraft demands that primary structural parts or equipment can snap without the aircraft breaking apart. This is called &lt;a href=&quot;https://aviation.stackexchange.com/questions/8950/can-a-passenger-jet-be-towed-to-safety-if-it-breaks-down-in-midair/8955#8955&quot;&gt;redundancy&lt;/a&gt;: Every primary structure and every flight-critical piece of equipment is duplicated, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/9409/how-strong-is-the-a380-fuselage-wing-joint/9418#9418&quot;&gt;if one part breaks&lt;/a&gt;, the other, redundant part will continue to carry the loads and the flight can be terminated as planned. Regular inspections make sure that such damage is caught quickly, and the manufacturers &lt;a href=&quot;http://en.wikipedia.org/wiki/Airworthiness_Directive&quot; rel=&quot;nofollow noreferrer&quot;&gt;continue to improve the existing fleet&lt;/a&gt; once a weakness has been spotted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if something snaps, it is extremely unlikely that the aircraft will enter a spin, and even if this happens, it is easy to end. Your fears are unfounded.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-01-08T15:00:18.020" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11369" PostTypeId="1" AcceptedAnswerId="11370" CreationDate="2014-12-25T23:18:42.263" Score="14" ViewCount="4457" Body="&lt;p&gt;Or is it just commercial aircraft? I was watching an episode of Scorpion where an &quot;F-120 Firehawk&quot; crashed and they looked at its black box. So, do normal, non-imaginary fighters have them?&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="1696" LastEditDate="2018-04-26T14:18:40.557" LastActivityDate="2018-04-26T14:18:40.557" Title="Do fighters have black boxes?" Tags="&lt;fighter&gt;&lt;accidents&gt;&lt;jet&gt;&lt;accident-investigation&gt;&lt;flight-data-recorder&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11370" PostTypeId="2" ParentId="11369" CreationDate="2014-12-25T23:25:34.627" Score="8" Body="&lt;p&gt;Yes, most military aircraft, including fighter aircraft, are equipped with a &quot;black box&quot; called flight data recorder (FDR) / crash survivable memory unit (CSMU) / integrated monitoring and recording system (IMRS) / deployable flight incident recorder set (DFIRS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources &lt;a href=&quot;http://www.armedforces-int.com/article/flight-data-recorders-crash-survivable-memory-units-tactical-military-aircraft.html&quot; rel=&quot;noreferrer&quot;&gt;1, ( B-1B, F-22, T-45, B-2, F-4, F-15, F-16, C-5 Galaxy, NATO AWACS, and the Space Shuttle)&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.defensemedianetwork.com/stories/%E2%80%9Cdfirs-phone-home%E2%80%9D/&quot; rel=&quot;noreferrer&quot;&gt;2. (F-18, floating black box)&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-03T09:28:26.063" LastActivityDate="2015-01-03T09:28:26.063" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11371" PostTypeId="1" AcceptedAnswerId="11372" CreationDate="2014-12-25T23:39:36.263" Score="1" ViewCount="221" Body="&lt;p&gt;First of all, I'm not totally positive that this will be well received here; I did read the related meta, but am unsure. &lt;a href=&quot;http://area51.stackexchange.com/proposals/63158/diy-drones/81453#81453&quot;&gt;I have also asked the question in support of the new Drone SE.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm new to drones, and I've been researching. Would it be a bad idea to start out as a beginner with the Inspire 1 (sort of the cutting edge, top of the line, nicest looking drone out there)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read somewhere that with Drones, unlike normal RC aircraft, (and large aircraft perhaps) the higher the price, the &lt;em&gt;easier&lt;/em&gt; the flying. I'm worried about whether or not getting a very high end drone as my first one might prove a foolish investment?&lt;/p&gt;&#xA;" OwnerUserId="4244" LastEditorUserId="3170" LastEditDate="2015-03-29T20:47:04.440" LastActivityDate="2015-03-29T20:47:04.440" Title="Is the Inspire 1 a good drone starter aircraft?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2014-12-26T10:27:29.843" ContentLicense="CC BY-SA 3.0" />
  <row Id="11372" PostTypeId="2" ParentId="11371" CreationDate="2014-12-26T00:11:56.827" Score="6" Body="&lt;p&gt;I'm not sure this question will remain open long but here's my $0.02:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You will &lt;strong&gt;definitely want to learn to fly a cheap quadcopter&lt;/strong&gt; before going expensive. Quadcopters are not &lt;em&gt;that&lt;/em&gt; easy to fly (there is a lot going on at the same time: 6 degrees of freedom being controlled in a changing frame of reference depending on orientation to a stationary pilot). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I crashed my cheap one a lot learning to fly it despite it being pretty stable, but it is robust and takes a good beating. A cheap one is a very low risk and pain compared to the one you're looking at: You're not going have to break a lot on the expensive one to recoup the investment of becoming acquainted to quadcopters before you started.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quadcopters may become a little 'smarter' as you go more expensive and be more stable, but it still requires good piloting. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="19" LastEditDate="2014-12-26T08:29:19.913" LastActivityDate="2014-12-26T08:29:19.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11373" PostTypeId="2" ParentId="11353" CreationDate="2014-12-26T01:49:44.403" Score="2" Body="&lt;p&gt;Keep in mind that less wing area means a higher stalling speed, which translates to more runway needed for TO &amp;amp; landing. Climb performance and max. altitude may also be reduced noticeably.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-26T01:49:44.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11374" PostTypeId="2" ParentId="11330" CreationDate="2014-12-26T03:13:19.613" Score="6" Body="&lt;p&gt;For their first flight 17 Dec 1903 they used a rail for takeoff, but NO CATAPULT. The Kill Devil Hills, North Carolina site was chosen for strong steady winds, so they DIDN'T NEED a catapult. And their first flight patent claim was to take off without external assistance, demonstrate stable controlled flight, and land at a site no lower than the takeoff point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The catapult was used only after their experiments were moved to Huffman Prairie near their home in Dayton, because the winds were less than in North Carolina.&lt;/p&gt;&#xA;" OwnerUserId="4508" LastActivityDate="2014-12-26T03:13:19.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11375" PostTypeId="1" AcceptedAnswerId="11382" CreationDate="2014-12-26T03:58:26.437" Score="8" ViewCount="2422" Body="&lt;p&gt;I work at a local small airport (very small, if we get more than about 10 or 15 airplanes taking off/landing it's a &quot;busy day&quot;) and I mow the runways (we have multiple grass ones).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the visual obstructions of the tractor's cabin that I use I have to be even more careful than normal to check for in-coming planes and so I started looking into getting an air band radio for the tractor. However, they can be fairly expensive - not something I'd invest in unless I absolutely had to - and so I started looking into making my own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd figured this was possible because I'd occasionally picked up communications on a cheap radio I had around my house (I live quite close to the airport, about a 5 minute bike ride). So, I went searching, and sure enough - this is a thing that is possible and has been done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found this post on Electrical Engineering.SE, &lt;a href=&quot;https://electronics.stackexchange.com/questions/16583/modify-an-am-fm-radio-to-an-airband-receiver-what-if-any-changes-to-the-demod&quot;&gt;Modify an AM/FM radio to an airband receiver&lt;/a&gt;, describing basically what could be done; and then this video done by MAKE, &lt;a href=&quot;https://www.youtube.com/watch?v=5kvxjNeWMxs&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weekend Project: Aircraft Band Receiver&lt;/a&gt;, showing it actually being done to cheap transistor radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, what I'm wondering is, is this a legal thing to do - or does the FAA have regulations on this sort of thing?&lt;/p&gt;&#xA;" OwnerUserId="5634" LastEditorUserId="-1" LastEditDate="2017-04-13T12:33:10.950" LastActivityDate="2019-12-20T19:32:58.570" Title="Is it legal to use a home-made Airband radio receiver in the United States?" Tags="&lt;faa-regulations&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="11376" PostTypeId="2" ParentId="11366" CreationDate="2014-12-26T09:10:38.990" Score="4" Body="&lt;p&gt;I don't know about if that is possible in the UK. However, in Spain it can be done at CESDA (at Reus airport LERS) which is linked to the URV (Universitat Rovira i Virgili), they accept students from all over Europe and they can be validate the corresponding high school exams for most of the countries (probably not all of them, but surely UK can).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to see further information you can check out this &lt;a href=&quot;http://www.cesda.com/en/aviation-degree&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; and read all the information but basically the most important features of the program are the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aim of the Degree in Commercial Airline Pilot and Air Operations is to prepare future professionals to adapt more easily to the exacting demands of the labour market, obtaining the EASA European license for commercial pilots with all the qualifications required for the “Frozen ATPL”.&lt;/li&gt;&#xA;&lt;li&gt;After graduation students will have completed a total of 285 flight hours, of which 171 are real flight hours, 54h on a basic simulator and 60h in the Multi Crew Cooperation (MCC) simulator.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I hope this helps, if you're considering studying outside of the UK. &lt;/p&gt;&#xA;" OwnerUserId="4358" LastActivityDate="2014-12-26T09:10:38.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11377" PostTypeId="2" ParentId="11332" CreationDate="2014-12-26T10:17:48.563" Score="2" Body="&lt;p&gt;Change doesn't necessarily bring improvements that are important to the mission. Do lightness, speed and size increase the odds of getting the President safely to his destination? They might, but the difference might not warrant the changes, especially when considering the downsides of change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AF1 is a known entity with known risks, mitigated over many years. After all this time, everything about the aircraft is so well known that flights have a very low risk profile. Everyone from flight crew to ground crew to security personnel have done this a thousand times, raising the odds of success in any given emergency. Introducing any change likely adds risks that outweigh a bit of fuel economy.&lt;/p&gt;&#xA;" OwnerUserId="5636" LastActivityDate="2014-12-26T10:17:48.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11378" PostTypeId="1" AcceptedAnswerId="11379" CreationDate="2014-12-26T12:58:26.803" Score="14" ViewCount="1624" Body="&lt;p&gt;Are there any ejector seat designs with built-in thrusters, or boosters, which the pilot can deploy to maneuver himself out of, or away from enemy territory?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A use case might be that after the parachute is deployed, the ejected pilot uses the thrusters to change direction or propel himself in a different path. &lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="65" LastEditDate="2014-12-26T15:01:34.037" LastActivityDate="2015-02-15T01:24:30.710" Title="Do any ejector seat designs include controllable thrusters?" Tags="&lt;ejection-seat&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11379" PostTypeId="2" ParentId="11378" CreationDate="2014-12-26T14:06:52.527" Score="16" Body="&lt;p&gt;Yes, modern ejection seats have rocket motors, but they are only for propelling the seat away from the aircraft and upwards, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1439/is-there-a-minimum-altitude-for-ejection-seats&quot;&gt;high enough for safe parachute deployment&lt;/a&gt;. An escape from enemy territory is not possible with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are controlled by a &lt;a href=&quot;http://www.academia.edu/5295096/9._EJECTION_SEAT_CAPABILITIES_TO_MEET_AGILE_AIRCRAFT_REQUIREMENTS&quot; rel=&quot;nofollow noreferrer&quot;&gt;guiding system inside the seat&lt;/a&gt;, but not by the pilot. Ejection by itself is stressful enough, controlling the seat would be too much for any pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, this is impressive technology. Even when ejected pointing downward at low altitude, the seat &lt;a href=&quot;http://www.military.com/video/aircraft/ejection-seats/are-russian-ejection-systems-better/903159086001/&quot; rel=&quot;nofollow noreferrer&quot;&gt;will change course and lift the pilot up&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The seat featured in the linked video is the Russian &lt;a href=&quot;http://en.wikipedia.org/wiki/NPP_Zvezda_K-36&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zvezda K-36&lt;/a&gt;, the only ejection seat which meets or exceeds all US Air Force performance demands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get &lt;a href=&quot;http://en.wikipedia.org/wiki/Behind_Enemy_Lines_(2001_film)&quot; rel=&quot;nofollow noreferrer&quot;&gt;downed pilots out from enemy territory&lt;/a&gt; the armed forces use helicopters. To build such a capacity into the seat would make it impossibly heavy and dangerous - would you like to sit on hundreds of kilos of jet or rocket fuel while being shot at? Just for the chance of flying home after ejection? And how deep are you allowed to fly into enemy territory for the system to work? No, this idea is a dead end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most promising concept today is to &lt;a href=&quot;http://en.wikipedia.org/wiki/Unmanned_combat_aerial_vehicle&quot; rel=&quot;nofollow noreferrer&quot;&gt;separate the pilot from the airplane&lt;/a&gt;, so he sits thousands of miles away while his craft flies deep into enemy territory. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2014-12-27T13:47:04.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11380" PostTypeId="1" AcceptedAnswerId="11383" CreationDate="2014-12-26T14:50:15.210" Score="10" ViewCount="723" Body="&lt;p&gt;When an instrument fails in the cockpit, it is better cover it with something, either a dollar bill or a gauge cover (if you happen to have one of those), so we won't accidentally process the information from the faulty reading. My instructor taught me to literally smash the gauge, so the status of that instrument is not in question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This works well in cockpits with rounded gauges. Nowadays, more and more GA aircrafts are fitted with glass cockpits. Obviously I can't just smash the screen, or else everything will be gone! What are the steps that one can take to avoid reacting to the faulty reading?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-03-02T07:19:00.977" LastActivityDate="2016-12-18T05:23:27.717" Title="How to ignore faulty instrument readings in glass cockpits?" Tags="&lt;emergency&gt;&lt;avionics&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11381" PostTypeId="2" ParentId="11378" CreationDate="2014-12-26T15:30:09.647" Score="6" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;, the small rockets present in an ejection seat are only for &lt;a href=&quot;http://en.wikipedia.org/wiki/Ejection_seat#Zero-zero_ejection_seat&quot; rel=&quot;nofollow&quot;&gt;zero-zero ejection&lt;/a&gt; situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although one can do some maneuverability using parachutes but the purpose of parachutes isn't traveling over land, but descending at a survivable speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scenario you mentioned is &lt;em&gt;ejection in hostile environments&lt;/em&gt;. Fighter pilots are trained for this and they are taught survival skills where they land. There are some &lt;a href=&quot;http://www.ncbi.nlm.nih.gov/pubmed/23926663&quot; rel=&quot;nofollow&quot;&gt;psychological aspects&lt;/a&gt; of this too.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-26T19:48:29.487" LastActivityDate="2014-12-26T19:48:29.487" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11382" PostTypeId="2" ParentId="11375" CreationDate="2014-12-26T15:58:51.593" Score="13" Body="&lt;p&gt;FYI, the runway is supposed to be closed XXX with NOTAM when it is mowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no FAA or FCC limit on constructing homemade airband receivers in the United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also construct transceivers. As long as you do not sell a transmitter you are allowed to make and operate up to 5 of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exemptions covering low power transmitters are covered in Part 15 of Title 47 in FCC regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum unlicensed radiated output power for airband is 500 μV/m @ 3 m. Typical commercial airband handheld transmitters go up to about 1 Watt and base stations up to 50 Watts. For your purposes a 1 Watt transceiver would probably be reasonable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that typical receiver/scanner designs have an oscillator in their mixer that can generate a small amount of RF noise. Normally the signal is so weak it is completely undetectable. Nevertheless, there are specialized receivers that have no oscillator that some people use to listen to airband with zero chance of interference.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="11215" LastEditDate="2019-12-20T16:53:46.407" LastActivityDate="2019-12-20T16:53:46.407" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="11383" PostTypeId="2" ParentId="11380" CreationDate="2014-12-26T16:09:20.047" Score="12" Body="&lt;p&gt;Like in a steam gauge cockpit, you can put adhesive INOP stickers on parts of the glass panel. &lt;a href=&quot;http://www.sportys.com/pilotshop/glass-cockpit-inop-stickers.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stickers for the Garmin G1000 are available commercially&lt;/a&gt;, and I had to use them extensively for my instrument rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind, though, that glass cockpit aviation systems will detect a faulty sensor automatically, and the faulty instrument will just appear X-ed out (like the picture on the INOP sticker) instead of showing wrong values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even multiple sensor source cross checks doesn't keep you safe from misinterpretation. See &lt;a href=&quot;http://en.wikipedia.org/wiki/Birgenair_Flight_301&quot; rel=&quot;nofollow noreferrer&quot;&gt;Birgenair 301&lt;/a&gt; accident for example.&lt;/p&gt;&#xA;" OwnerUserId="577" LastEditorUserId="755" LastEditDate="2016-12-18T05:23:27.717" LastActivityDate="2016-12-18T05:23:27.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11384" PostTypeId="2" ParentId="11369" CreationDate="2014-12-27T05:13:53.113" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Do fighters have black boxes?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Almost all the 4th gen and 5th gen fighter jets have a flight recorder a.k.a Black Box.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I was watching an episode of where an &quot;F-120 Firehawk&quot; crashed and&#xA;  they looked at its black box.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In case of a crash both the Black Box and the Ejection Chip will have to be examined to ascertain the cause of the crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data is stored in stacked semiconductor dynamic RAM memory boards.The manufacturers supply the software and hardware needed to read and analyze the data&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2014-12-27T05:31:49.667" LastActivityDate="2014-12-27T05:31:49.667" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11386" PostTypeId="2" ParentId="11366" CreationDate="2014-12-27T15:34:37.317" Score="9" Body="&lt;p&gt;One UK list is &lt;a href=&quot;http://www.flightdeckfriend.com/#!university-pilot-degree-course/c235l&quot;&gt;here&lt;/a&gt;, it mentions several universities that include PPL and/or ATPL training in the degree course, but they appear to cover only the theory part of the courses with actual flight training being optional. Where a full PPL is included, they mention extra costs of around GBP 7000 on top of regular tuition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look directly at the university sites they seem to confirm this: &lt;a href=&quot;http://www.engineering.leeds.ac.uk/chemical/undergraduate/degree-aviation-technology-pilot-studies/&quot;&gt;Leeds&lt;/a&gt; includes only 10 flight hours for the PPL; &lt;a href=&quot;http://www.brunel.ac.uk/courses/undergraduate/aviation-engineering-with-pilot-studies-beng&quot;&gt;Brunel&lt;/a&gt; and &lt;a href=&quot;http://www.salford.ac.uk/ug-courses/aviation-technology-with-pilot-studies&quot;&gt;Salford&lt;/a&gt; both include a UK NPPL but at extra cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might be able to get a scholarship of some kind to cover all or part of your tuition, but that depends very heavily on your personal situation and what the individual university offers. Finally, you could consider the RAF as an alternative route to paid flight training but I have no idea if that's of any interest to you and I imagine that competition for cockpit places is very tough.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-27T15:34:37.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11387" PostTypeId="1" AcceptedAnswerId="11390" CreationDate="2014-12-27T17:34:56.270" Score="7" ViewCount="2863" Body="&lt;p&gt;In terms of technical capability, what are the comparative advantages and disadvantages between the following?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.duats.com/&quot; rel=&quot;nofollow&quot;&gt;CSC DUATS&lt;/a&gt; from &lt;em&gt;Computer Sciences Corporation&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.duat.com/&quot; rel=&quot;nofollow&quot;&gt;DTC DUAT&lt;/a&gt; from &lt;em&gt;Data Transformation Corporation&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.1800wxbrief.com/&quot; rel=&quot;nofollow&quot;&gt;www.1800wxbrief.com&lt;/a&gt; from &lt;em&gt;Lockheed-Martin&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2014-12-28T00:19:05.320" LastActivityDate="2014-12-28T02:05:17.047" Title="How do the various DUATS differ?" Tags="&lt;weather&gt;&lt;usa&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11388" PostTypeId="2" ParentId="3513" CreationDate="2014-12-27T17:49:53.067" Score="1" Body="&lt;p&gt;Small aircraft dont need the only advantage turboprop allows: more power to weight ratio.&#xA;A turboprop is more combersome than a piston engine for lower power to weight ratios&#xA;It will not save so much weight comparing to a small displacement piston engine since a lot of the weight comprises other parts of the propulsion system beside the engine ( gears, fuel systems, cooling, charging system, propeler, etc), and a turbine allways consumes more fuel.&lt;/p&gt;&#xA;" OwnerUserId="5643" LastActivityDate="2014-12-27T17:49:53.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11390" PostTypeId="2" ParentId="11387" CreationDate="2014-12-28T00:03:33.000" Score="6" Body="&lt;p&gt;Both DUAT (DTC) and DUATS (CSC) provide the same information. They are functionally equivalent.&lt;br&gt;&#xA;You also left one out: Lockheed-Martin operates a web-based briefing service at &#xA;&lt;a href=&quot;https://www.1800wxbrief.com/&quot;&gt;https://www.1800wxbrief.com/&lt;/a&gt; .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which you prefer to use for interactive access is largely an aesthetic consideration - as a pilot you can sign up for an account on each of these services, so the usual advice is to sign up for all of them and use the one you like better (personally I used to prefer DTC's DUAT interface, but the direct (1800wxbrief.com) system is a now my preference for web-based briefings when I'm not using ForeFlight).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From a non-interactive standpoint, CSC DUATS has an API that can be used by other programs (like ForeFlight) to receive weather/NOTAMs/etc. and to file flight plans. This can be advantageous, however Lockheed-Martin has recently (2013) implemented an XML-based API that lets application developers directly communicate with the automated flight service system, and it is likely that this will be the preferred way to handle this sort of thing as time goes on.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2014-12-28T00:03:33.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11391" PostTypeId="2" ParentId="11387" CreationDate="2014-12-28T00:16:29.953" Score="4" Body="&lt;p&gt;Technically, there shouldn't be a difference between these providers. Both providers were tested by FAA to confirm that their major functions meet FAA's standards and requirements. Although, each service service has slightly different features and presents the information in different ways. It is more a matter of personal preference and likeliness, and one's comfortableness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both these services use FAA database to obtain weather and aeronautical information and to file, amend, and cancel flight plans. They provide direct access to weather information via a &lt;a href=&quot;http://en.wikipedia.org/wiki/National_Airspace_System&quot; rel=&quot;nofollow&quot;&gt;National Airspace System&lt;/a&gt; Data Interchange Network II (NADIN-II) interface to the &lt;a href=&quot;http://govcomm.harris.com/solutions/products/atc/wmscr-atc.asp&quot; rel=&quot;nofollow&quot;&gt;Weather Message Switching Center Replacement&lt;/a&gt; (WMSCR) System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition the to above mentioned services, many people like &lt;a href=&quot;http://www.fltplan.com/&quot; rel=&quot;nofollow&quot;&gt;FltPlan&lt;/a&gt;. It is also approved by FAA. FltPlan is is funded by advertising and provides a better format and information than government subsidized programs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationweather.gov/adds/&quot; rel=&quot;nofollow&quot;&gt;Aviation Weather Center&lt;/a&gt; is another option (&lt;em&gt;Aviation Digital Data Service&lt;/em&gt;) which is funded by FAA. It is an excellent source for icing conditions. It does not meet all requirements of FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bottom line is that whichever service tells you &lt;strong&gt;all&lt;/strong&gt; the information and you are comfortable with it not to miss any critical information is the most suitable for you. However, many people plan their flights in one service and then double check it with others to make sure that they haven't missed anything.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-28T02:05:17.047" LastActivityDate="2014-12-28T02:05:17.047" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11392" PostTypeId="2" ParentId="11332" CreationDate="2014-12-28T20:35:53.873" Score="2" Body="&lt;p&gt;As a former RAF pilot has pointed out, when the Army decides on a new rifle the amount of disruption and retraining per involved person is small.  When the RAF decides on a new aeroplane, the amount of disruption and retraining per involved person is enormous.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus it pays not to replace aircraft without actual need.&lt;/p&gt;&#xA;" OwnerUserId="5651" LastActivityDate="2014-12-28T20:35:53.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11393" PostTypeId="1" AcceptedAnswerId="11394" CreationDate="2014-12-28T23:02:10.020" Score="22" ViewCount="9295" Body="&lt;p&gt;In the US, is there a highest legal altitude allowed for certain planes and does it depend on the plane? I heard from a sort-of-reliable source that the maximum is 45,000 feet but I haven't been able to confirm this. I ask since a plane I travelled in very recently was travelling at an altitude of over 55,000 feet and, when it did, turbulence was terrible (some told me I was lucky to be alive). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note&lt;/em&gt;: I have tried Googling this and have found no answers. &lt;/p&gt;&#xA;" OwnerUserId="5653" LastEditorUserId="19" LastEditDate="2015-02-18T20:37:17.473" LastActivityDate="2019-07-18T08:21:38.977" Title="Is there a legal maximum altitude?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;aircraft-limitations&gt;&lt;altitude&gt;" AnswerCount="4" CommentCount="17" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11394" PostTypeId="2" ParentId="11393" CreationDate="2014-12-28T23:21:06.673" Score="24" Body="&lt;p&gt;There's no legal limit of how high you're allowed to fly by law: there's no law that says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is illegal to fly above X,000ft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In some juristictions there are more specific laws, eg&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is illegal to operate an unpressurised aircraft above 25,000ft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, each aircraft has a service ceiling when it is certified, and it would be generally illegal to operate the aircraft above this altitude (because it's unsafe).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm fairly confident that you weren't at 55,000ft. No currently-operating commercial airliner I know of has a service ceiling higher than 45,000ft (the newer -800 version of the 747) and they almost never operate above 41,000ft. A few private jets can go a little higher, up to around 50,000ft, but I know of no non-military/experimental aircraft which is currently capable of going much above 50,000ft, even if you were daft enough to try.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2019-04-08T16:48:34.790" LastActivityDate="2019-04-08T16:48:34.790" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="11395" PostTypeId="1" AcceptedAnswerId="11425" CreationDate="2014-12-28T23:52:18.090" Score="8" ViewCount="6866" Body="&lt;p&gt;I have some concerns about the level of maintenance and service on some rental airplanes on an out of town trip.&lt;/p&gt;&#xA;&lt;p&gt;The first airplane I rented had some misgivings, so I went on a different one today. It was a Cessna 172 and had a Cylinder Head Temperature (CHT) monitor, which I hadn't seen before. So while on an extended leg I fiddled with it. Three of the cylinders where 340-350.  However, cylinder 2 was only 280. That seems like a significant outlier.&lt;/p&gt;&#xA;&lt;p&gt;Since most rental airplanes don't have a CHT monitor, I don't have experience with what is the normal temperature. Should I be concerned that one cylinder isn't close to the other three?&lt;/p&gt;&#xA;&lt;p&gt;Below is some information about the airplane and that flight:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Power: 2400 RPM&lt;/li&gt;&#xA;&lt;li&gt;Altitude: 7500 feet&lt;/li&gt;&#xA;&lt;li&gt;Oil Quantity: 7 quarts&lt;/li&gt;&#xA;&lt;li&gt;Oil Pressure: Top of green arc&lt;/li&gt;&#xA;&lt;li&gt;Oil Temperature: Normal&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Airplane was fresh out of a 100-hr maintenance&lt;/p&gt;&#xA;&lt;p&gt;Anomalous Cylinder: #2&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There was some issue with the engine during the 100-hr maintenance which held it up, but was signed off by a mechanic with an IA.&lt;/p&gt;&#xA;&lt;p&gt;I am unsure about the quality of maintenance service there. We had two flights cancelled in a row because &lt;em&gt;the carburetor  was fine when it was warm, but this cold snap (38°F) is making it &lt;strike&gt;hard&lt;/strike&gt; impossible to start&lt;/em&gt;. In addition, there are all sorts of small squawks such as trim that was out of whack etc.&lt;/p&gt;&#xA;&lt;p&gt;The bottom line is that I am concerned about my safety as probably I will be renting one more time. Is the above mentioned scenario something which could indicate a problem, or more likely something harmless? I have doubts that the maintenance is top quality, but I'm unsure if it's bad enough that I should just opt out.&lt;/p&gt;&#xA;" OwnerUserId="3516" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-03-13T16:12:57.493" Title="Is a lower CHT on one cylinder cause for concern?" Tags="&lt;piston-engine&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11396" PostTypeId="2" ParentId="311" CreationDate="2014-12-29T00:26:22.147" Score="22" Body="&lt;p&gt;For a simple &lt;strong&gt;and&lt;/strong&gt; correct answer you need first to understand induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please read &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;this answer&lt;/a&gt; if you feel unsure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short version: The wing creates lift by deflecting air downwards. Induced drag is the consequence of this deflecting, because the resulting force of this deflection process is tilted backwards by half the deflection angle. Due to the backward tilt, the force has a horizontal component, pointing backwards. This is induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AGhZF.png&quot; alt=&quot;streamlines around a wing and direction of impulses&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ground effect will prevent this flow field from developing fully, because air cannot flow into the ground. Consequently, the deflection angle is lower, and also its horizontal component, i.e. drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same happens ahead of the wing, where the upward motion of air ahead of the stagnation point is also restricted. Another consequence of this is a reduced &lt;a href=&quot;https://aviation.stackexchange.com/questions/14508/what-is-the-method-to-calculate-a-finite-wings-lift-from-its-sectional-airfoil/14559#14559&quot;&gt;lift curve slope&lt;/a&gt; in ground effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is higher relative to induced drag compared to the free-flow case because the wing somewhat blocks the outflow of air at the trailing edge, and this results in a higher pressure on the bottom of the wing compared to the free-flow case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &quot;cushion-effect&quot; explanation is actually quite correct. The pressure which lifts the airplane is not only created by accelerating air downwards, but also by ram pressure. This effect disappears once the wing is far enough from the ground.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-04-30T13:03:55.407" LastActivityDate="2017-04-30T13:03:55.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11397" PostTypeId="2" ParentId="11395" CreationDate="2014-12-29T01:21:50.737" Score="2" Body="&lt;p&gt;Seems low, but there could be some non-maintenance reasons that a pilot can either see or adjust that have an impact on CHTs. The three most important factors relating to CHT are oil, airflow, and power setting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did you check the oil quantity before you flew? It should be in the normal range and of the proper type. You can tell what oil is likely to be in the engine because that'll be the extra quart in the baggage compartment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often the front-most cylinders will be the coolest because they are directly exposed to the airflow. For other cylinders, there are rubber air gaskets that direct the airflow over the cylinder heads.  These gaskets can get dislodged and cause assymetrical CHTs. Pitch attitude and cowl flap position also affect airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power setting and leaning can be adjusted in flight to control CHTs. Lower settings and richer mixtures will show lower temps. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2014-12-29T01:27:22.417" LastActivityDate="2014-12-29T01:27:22.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11400" PostTypeId="2" ParentId="11309" CreationDate="2014-12-29T16:30:07.340" Score="4" Body="&lt;p&gt;As far as I can find out, no one knows. There's no good data available on engine reliability from the manufacturers - although they usually don't share that information anyway - and nothing substantial that I could find from any third parties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is some information online, although it's mostly opinions and there's no real, consistent data to support it. &lt;a href=&quot;http://www.aviationsafetymagazine.com/airplane/LSA-Engine-Safety.html&quot; rel=&quot;nofollow&quot;&gt;This 2008 article&lt;/a&gt; compared LSA engine options including the Rotax and said that there were more incidents involving Rotaxes than Jabiru engines (excluding non-engine related causes), but there were also many more Rotaxes in service so the comparison isn't meaningful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, the article said that any comparison is difficult because the Rotax was (is?) primarily used in experimental aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The great problem in identifying engine-specific problems is that in&#xA;  the majority of installations, the engines power&#xA;  experimental/amateur-built category aircraft, where differences in&#xA;  mounting, accessory placement, cooling and vibration variations can&#xA;  instill issues that vary from one installation to another&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And it also made the point that there are plenty of engine-related incidents involving Continentals:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And accidents involving Continental O-200-powered craft were as&#xA;  numerous as you'd expect for the length and depth of its presence in&#xA;  general aviation aircraft. Here again, many occurred through no fault&#xA;  of the engine. Still, numerous reports involved engine stoppages,&#xA;  heat-related power loss and other engine problems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article's conclusion seems to be that a Rotax engine is not (was not) significantly different from any other engine:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To paraphrase the words of one long-time Rotax service-center&#xA;  operator, the main problems involving the engines stem from many of&#xA;  the same types of problems—poor judgment, misuse, mismanagement and&#xA;  poor maintenance—befalling all aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I found various other forum discussions about &lt;a href=&quot;http://sportpilottalk.com/viewtopic.php?t=1478&quot; rel=&quot;nofollow&quot;&gt;engine noise&lt;/a&gt; (no conclusion), &lt;a href=&quot;https://www.backcountrypilot.org/forum/cont-200-and-rotax-912-s-uls-fuel-efficiency-comparison-8672&quot; rel=&quot;nofollow&quot;&gt;fuel efficiency&lt;/a&gt; (Rotax is better), &lt;a href=&quot;http://www.rotax-owner.com/rotax-forum/3-4-stroke-technical-questions/4678-o-200-vs-rotax-912-costs&quot; rel=&quot;nofollow&quot;&gt;maintenance costs&lt;/a&gt; (some preference for Rotax) and so on, but nothing authoritative. I suspect that a detailed, data-based comparison simply doesn't exist; finding anything for Lycoming vs Continental is difficult, even with the much longer history and larger installed base.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, engine comparisons seem to be mostly based on opinion and anecdote (as described &lt;a href=&quot;http://www.avweb.com/news/maint/182849-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;). That doesn't mean the information is useless, but you do have to spend some time sifting and weighing the opinions to reach your own conclusions.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-29T16:30:07.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11401" PostTypeId="5" CreationDate="2014-12-29T18:10:02.317" Score="0" Body="&lt;p&gt;&lt;em&gt;Fighter jet&lt;/em&gt; is a commonly used but informal term for a modern, jet-propelled military air-to-air combat aircraft. This term usually excludes bombers, but may include ground-attack or close support aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for general questions about modern military combat aircraft, but include other, more specific tags wherever possible.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Fighter_aircraft&quot; rel=&quot;nofollow&quot;&gt;Fighter aircraft&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow&quot;&gt;Jet engine&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-31T15:21:14.707" LastActivityDate="2014-12-31T15:21:14.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11402" PostTypeId="4" CreationDate="2014-12-29T18:10:02.317" Score="0" Body="This tag is being decommissioned (https://aviation.meta.stackexchange.com/q/3188/1467) Please use the &quot;fighter&quot; and/or &quot;jet&quot; tag(s)." OwnerUserId="62" LastEditorUserId="1467" LastEditDate="2017-04-04T11:11:58.933" LastActivityDate="2017-04-04T11:11:58.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11403" PostTypeId="5" CreationDate="2014-12-29T18:13:54.993" Score="0" Body="&lt;p&gt;&lt;em&gt;Jet&lt;/em&gt; is a commonly used but informal term for any modern aircraft propelled by one or more &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for general questions about modern jet aircraft, but include other, more specific tags wherever possible; &lt;em&gt;jet&lt;/em&gt; by itself is a very broad term.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jet engine&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-05-27T04:29:21.043" LastActivityDate="2019-05-27T04:29:21.043" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="11404" PostTypeId="4" CreationDate="2014-12-29T18:13:54.993" Score="0" Body="*Jet* is a generic, informal term for an aircraft with jet propulsion. In a civilian context it may refer to an airliner or small private jet." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-31T15:20:22.100" LastActivityDate="2014-12-31T15:20:22.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11405" PostTypeId="5" CreationDate="2014-12-29T18:29:14.040" Score="0" Body="&lt;p&gt;Security is a very broad topic and covers all measures taken on the ground and in the air to protect aircraft, passengers and crew from sabotage, hijacking or other deliberate, malicious attacks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that security should not be confused with safety, which is concerned with protection against accidents and other unintended dangers. Some questions may concern both safety and security.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about how aviation security is measured, achieved and improved, but note that some information - such as details of cockpit and crew protocols - may be not be public and it may even be illegal to make it public.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions that are purely about ground security measures (e.g. passenger documents, identification and background checks, luggage screening) are often off-topic unless there is some very direct relevance to actual flight operations; in those cases you may get a better answer on &lt;a href=&quot;http://travel.stackexchange.com/&quot;&gt;travel.SE&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-29T18:29:14.040" LastActivityDate="2014-12-29T18:29:14.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11406" PostTypeId="4" CreationDate="2014-12-29T18:29:14.040" Score="0" Body="Security refers to protecting aircraft, passengers and crew from deliberate attacks or sabotage" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-29T18:29:14.040" LastActivityDate="2014-12-29T18:29:14.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11407" PostTypeId="5" CreationDate="2014-12-29T19:57:04.320" Score="0" Body="&lt;p&gt;An engine failure is any failure of an engine to produce power normally as commanded by the pilot. There are three main scenarios:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engine stops producing power completely&lt;/li&gt;&#xA;&lt;li&gt;The engine produces less power than commanded (partial power loss)&lt;/li&gt;&#xA;&lt;li&gt;The engine produces more power than commanded&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In basic pilot training in a single-engine aircraft, an &quot;engine failure&quot; almost always means a complete power loss from the engine, but pilots may train for other scenarios. If an engine stops because of fuel exhaustion or starvation, it is not usually considered to be an engine failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The response to an engine failure depends on how many engines the aircraft has and what the nature of the failure is. All powered aircraft have checklists and procedures for use in the event of engine failure, although if the failure occurs at a low altitude there may be little time to use them and therefore pilots are expected to memorize the most critical actions to take.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a single-engine aircraft, if the engine fails completely the pilot will typically trim the aircraft to glide as efficiently as possible and then execute an emergency landing; if time allows he may run through an engine failure checklist or attempt to restart the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a multi-engine aircraft, the pilot will first stabilize the aircraft - to compensate for the asymmetric thrust from the remaining engine(s) - and then run a checklist, plan a diversion to an alternate landing site or take other action as required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Engine_failure_on_take-off&quot; rel=&quot;nofollow noreferrer&quot;&gt;Engine failure on takeoff&lt;/a&gt; is a specific scenario in pilot training and a real failure is considered very challenging to handle because the pilot must react immediately with limited time and altitude available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for questions about training for or handling engine failures in any aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see the Wikipedia articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Turbine_engine_failure&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turbine engine failure&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Engine_failure_on_take-off&quot; rel=&quot;nofollow noreferrer&quot;&gt;Engine failure on take-off&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="22726" LastEditDate="2019-02-04T13:03:01.323" LastActivityDate="2019-02-04T13:03:01.323" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="11408" PostTypeId="4" CreationDate="2014-12-29T19:57:04.320" Score="0" Body="An engine failure occurs when one or more engines on an aircraft stop functioning normally. This is often assumed to mean a complete loss of power from the engine, but partial power loss and excess power are also engine failures." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-29T19:57:04.320" LastActivityDate="2014-12-29T19:57:04.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11409" PostTypeId="5" CreationDate="2014-12-29T20:19:16.460" Score="0" Body="&lt;p&gt;Every aircraft's operating handbook includes the operating limitations of the aircraft. These are limits for altitude, speed weight etc. that have been tested and documented by the manufacturer. Pilots should not operate an aircraft outside its limitations for safety reasons, and doing so may be illegal under local regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Limitations can apply to many areas of operation, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airspeed, e.g. maximum airspeed with flaps extended&lt;/li&gt;&#xA;&lt;li&gt;Engine, e.g. maximum RPM or manifold pressure&lt;/li&gt;&#xA;&lt;li&gt;Weight and balance, e.g. maximum takeoff or landing weight&lt;/li&gt;&#xA;&lt;li&gt;Maneuvers, e.g. no spinning&lt;/li&gt;&#xA;&lt;li&gt;Flight rules, e.g. no IFR flights&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's important to note that performance limitations are set by the manufacturer during the testing and certification of a new aircraft type and there may be other limits set by regulation that pilots must also observe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions about limitations on aircraft performance. Questions about limitations set by law should usually be tagged with the appropriate regulations tag as well.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-28T16:15:30.760" LastActivityDate="2015-01-28T16:15:30.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11410" PostTypeId="4" CreationDate="2014-12-29T20:19:16.460" Score="0" Body="All aircraft have specified performance limitations that they cannot (or at least should not) exceed, for altitude, speed, weight etc." OwnerUserId="62" LastEditorUserId="62" LastEditDate="2014-12-29T20:19:16.460" LastActivityDate="2014-12-29T20:19:16.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11411" PostTypeId="1" CreationDate="2014-12-29T21:08:01.023" Score="16" ViewCount="981" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11393/highest-permitted-altitude&quot;&gt;This question&lt;/a&gt; which claims that an altitude of 55,000 ft. was observed on a passenger's in-flight entertainment system on an Emirates B777 made me wonder: What are the normal sources of information for the flight data displayed on passenger IFE systems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of particular interest are the common sources for the following information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Altitude (Is this a pressure altitude? Indicated altitude? A GPS-measured altitude? A radio-altimeter-measured absolute altitude?)&lt;/li&gt;&#xA;&lt;li&gt;Speed (This seems to typically be true ground speed, which I'd assume comes from GPS, but any further insight would be appreciated)&lt;/li&gt;&#xA;&lt;li&gt;Latitude/Longitude position (Is this from GPS? INS? radionav? some combination?)&lt;/li&gt;&#xA;&lt;li&gt;Wind speed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2017-11-24T18:34:23.643" Title="What is the source for the flight data shown on in-flight entertainment systems?" Tags="&lt;airliner&gt;&lt;inflight-entertainment&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11412" PostTypeId="1" AcceptedAnswerId="11434" CreationDate="2014-12-29T21:35:26.770" Score="10" ViewCount="2877" Body="&lt;p&gt;When I file a flight plan I can file under either IFR or VFR flight rules. However, the &lt;a href=&quot;https://www.1800wxbrief.com&quot; rel=&quot;nofollow&quot;&gt;Lockheed Martin Flight Services website&lt;/a&gt; has the following options in addition to IFR/VFR:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;MVFR&lt;/li&gt;&#xA;&lt;li&gt;MIFR&lt;/li&gt;&#xA;&lt;li&gt;YFR&lt;/li&gt;&#xA;&lt;li&gt;ZFR&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;1 and 2 are only available for US domestic flight plans; 3 and 4 are only available for ICAO plans. What are all these options and when should I use them?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-11-29T22:20:29.467" LastActivityDate="2016-11-29T22:20:29.467" Title="In the Lockheed Martin Flight Services system, what are MIFR, MVFR, YFR and ZFR flight rules?" Tags="&lt;faa-regulations&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11414" PostTypeId="2" ParentId="11412" CreationDate="2014-12-29T21:58:26.557" Score="-1" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;MVFR&lt;/strong&gt;: Minimum/Marginal Visual Flight Rules&lt;br/&gt;&#xA;This refers to the general weather conditions pilots can expect at the surface. MVFR criteria means a ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility.&lt;sup&gt;1, 2&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;YFR&lt;/strong&gt;&lt;br/&gt;&#xA;Flight initially being IFR then going VFR&lt;sup&gt;3&lt;/sup&gt;&#xA;&lt;br/&gt;&lt;em&gt;...or...&lt;/em&gt;&lt;br/&gt;&#xA;Flights that will initially will be operated under IFR, followed by one or&#xA;more changes of flight rules.&lt;sup&gt;4&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;ZFR&lt;/strong&gt;&lt;br/&gt;&#xA;Flight initially being VFR then going IFR&lt;sup&gt;3&lt;/sup&gt;&#xA;&lt;br/&gt;&lt;em&gt;...or...&lt;/em&gt;&lt;br/&gt;&#xA;Flights that will initially will be operated under VFR, followed by one or&#xA;more changes of flight rules.&lt;sup&gt;4&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;MIFR&lt;/strong&gt;: Multi-engine IFR&lt;sup&gt;5&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;a href=&quot;http://forecast.weather.gov/glossary.php?word=MVFR&quot; rel=&quot;nofollow&quot;&gt;NOAA National Weather Service&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;: &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20080229171804AARmrjJ&quot; rel=&quot;nofollow&quot;&gt;YahooAnswer&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;: &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=71007&quot; rel=&quot;nofollow&quot;&gt;PilotsOfAmerica&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;4&lt;/sup&gt;: &lt;a href=&quot;http://cloudfront.foreflight.com/docs/ff/6.0/v6.0%20-%20filing%20with%20foreflight%20mobile.pdf&quot; rel=&quot;nofollow&quot;&gt;ForeFlight&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;5&lt;/sup&gt;: &lt;a href=&quot;http://www.cfc.aero/index.php/flight-training/ifr&quot; rel=&quot;nofollow&quot;&gt;Canadian Fight Center&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2014-12-29T22:30:07.450" LastActivityDate="2014-12-29T22:30:07.450" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11415" PostTypeId="1" AcceptedAnswerId="11423" CreationDate="2014-12-29T22:35:13.613" Score="8" ViewCount="991" Body="&lt;p&gt;I've just read &lt;a href=&quot;http://chrisvoncsefalvay.com/2014/12/28/how-to-lose-a-plane.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt; about the disappearance of &lt;code&gt;QZ8501&lt;/code&gt; and was surprised by the following statement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Even with automated beacons (we can assume these weren’t used, weren’t&#xA;  on board or were intentionally disabled) and EPIRBs, &lt;em&gt;losing an&#xA;  aircraft is actually not that difficult&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Now, is it?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was under the impression that if Breitling can make a watch with a 406 MHz distress beacon, a €70 million aircraft must surely be equipped with an automated ELT that can start to transmit automatically and whose signal can be picked up by [LE/GE]OSAR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/336/3868&quot;&gt;As it seems&lt;/a&gt;, US-registered civil aircraft are not required to carry 406 MHz ELTs while aircraft registered in Australia must be equipped with ELTs that operate on both 406 and 121.5 MHz (see the same reference).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you shed some light upon what is the current state of ELT regulations, how ELTs fitted to commercial aircraft operate in case of distress (automatic/manual?), what are the relevant regulations for EU-registered aircraft, and how can one lose an aircraft when all these systems operate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't buy that &lt;em&gt;“losing an aircraft is actually not that difficult”&lt;/em&gt; if all available technology is used (even assuming little redundancy and an adequate price range).&lt;/p&gt;&#xA;" OwnerUserId="3868" LastEditorUserId="7532" LastEditDate="2017-12-13T01:11:24.557" LastActivityDate="2017-12-13T01:11:24.557" Title="How to lose an aircraft?" Tags="&lt;emergency&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11416" PostTypeId="1" AcceptedAnswerId="11417" CreationDate="2014-12-29T22:51:37.500" Score="18" ViewCount="3567" Body="&lt;p&gt;It is a dreaded scenario; forgetting to secure the fuel cap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the low pressure area generated above the wing will siphon fuel out of wing tanks, how fast would this happen in a smaller GA airplane with wing tanks (something like the Cherokee perhaps) if the fuel cap was to be completely forgotten (rather than just not tightened)? Also, would it be able to suck the tank completely dry or would there be some limit to the amount of fuel that might be lost this way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just had X-plane do this to me while doing some IFR practice and it reduced my fuel with about 2 gallons/minute per tank until they were both completely empty and I was wondering if this is realistic.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2014-12-30T00:11:06.993" LastActivityDate="2017-09-17T13:59:31.957" Title="How fast can fuel be siphoned out if you leave the cap off?" Tags="&lt;aerodynamics&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11417" PostTypeId="2" ParentId="11416" CreationDate="2014-12-29T23:15:46.083" Score="19" Body="&lt;p&gt;It can happen &lt;em&gt;very quickly&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have exact numbers, but an acquaintance had this happen in a Cessna 172 and the entire tank was emptied in just a few minutes - the amount of time it took to do one circuit of the pattern and land. The fuel cap was not in the filler neck on departure, and was hanging from the chain, banging against the wing. The moral of that story is: never assume the fuelers put the cap back in.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I've personally flown an older Cherokee 160 that had a loose fuel tank gasket. When doing slow flight, the pressure above the wing was so strong that it would start to ooze fuel from the cap. Fuel would flow in a rather frightening amount back along the wing, and that's with the cap still on.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2014-12-30T07:58:31.653" LastActivityDate="2014-12-30T07:58:31.653" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11418" PostTypeId="5" CreationDate="2014-12-29T23:33:56.647" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2014-12-29T23:33:56.647" LastActivityDate="2014-12-29T23:33:56.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11419" PostTypeId="4" CreationDate="2014-12-29T23:33:56.647" Score="0" Body="For questions concerning in-flight entertainment on screens placed on, in front of, or behind seats. " OwnerUserId="5653" LastEditorUserId="5653" LastEditDate="2014-12-30T03:36:07.403" LastActivityDate="2014-12-30T03:36:07.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11422" PostTypeId="1" CreationDate="2014-12-29T23:45:48.710" Score="8" ViewCount="671" Body="&lt;p&gt;Plywood sheets can penetrate tree trunks unscathed - when pushed by hurricane or tornado winds.  Why wouldn't an airplane fuselage, wings and tail behave the same way impacting ocean water at a steep angle at 300-500 mph?  That is, penetrate and remain intact. I have seen a lot of supposition written about this which seems based on common sense, but common sense might be misleading.  Has  the outcome of such an event ever been demonstrated?&lt;/p&gt;&#xA;" OwnerUserId="5660" LastEditorUserId="22550" LastEditDate="2018-12-20T03:19:47.490" LastActivityDate="2018-12-20T03:19:47.490" Title="Why do high-speed water impacts / ditching usually result in structural loss of the airframe?" Tags="&lt;emergency&gt;&lt;ditching&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11423" PostTypeId="2" ParentId="11415" CreationDate="2014-12-30T00:17:14.633" Score="6" Body="&lt;p&gt;It is certainly &lt;em&gt;possible&lt;/em&gt; to build an aircraft using modern technology that is hard to lose. After all, aircraft have GPS receivers and passengers can watch YouTube in the cabin. All you have to do is integrate those two and send the exact GPS position to a ground station as frequently as you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the global aircraft fleet is not so capable. Some aircraft have satellite internet capability; some do not. For those that do, the internet connectivity is completely isolated from the aircraft navigation systems. (After all, you don't want any possibility that an aircraft in flight could be &quot;hacked&quot; by someone on the ground.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Retrofitting an existing aircraft (which could be up to 40 years old or more) to add such capability would be a very expensive job. Retrofitting an entire fleet (with perhaps many different aircraft models) is astoundingly expensive. Existing aircraft navigation and communications systems are so good that losing an aircraft &quot;almost never&quot; happens (yes, it's happened at least twice this year), compared to the number of successful flights. The airlines probably consider upgrading their fleet to support this kind of continuous surveillance not worth the expense, when compared to the probability that one of their aircraft actually goes missing.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-12-30T00:17:14.633" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11424" PostTypeId="2" ParentId="11422" CreationDate="2014-12-30T00:25:01.310" Score="3" Body="&lt;p&gt;In the case of plywood penetrating a tree trunk, consider the conservation of energy. The plywood might be flying at a certain speed before impact, some kinetic energy is used to break the tree trunk, and then the plywood (presumably) keeps flying at a reduced speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still considering conservation of energy, an aircraft impacting the ocean obviously cannot &quot;continue&quot; flying at a similar speed, so all that kinetic energy (and there is a &lt;em&gt;lot&lt;/em&gt; of it) must be used to do some work. That work will be crushing the (relatively delicate) airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to make a missile or something that can penetrate water (eg. &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_torpedo&quot; rel=&quot;nofollow&quot;&gt;Aerial torpedo&lt;/a&gt;). However, such things are designed to do so and passenger aircraft are definitely not.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2014-12-30T00:25:01.310" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11425" PostTypeId="2" ParentId="11395" CreationDate="2014-12-30T05:19:25.597" Score="7" Body="&lt;p&gt;A 60 degree difference in CHT is something worth investigating: It may not be a safety-related issue, but you want to know if it's &quot;normal&quot; for the engine or an indication of a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order from roughly &quot;Most Benign&quot; to &quot;Worst Case&quot;, the CHT difference could be the result of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;A faulty CHT probe&lt;/strong&gt;&lt;br&gt;&#xA;Either the probe is not seated in the cylinder head well properly, or the probe/wiring is defective and causing an inaccurate reading.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Different CHT Probe Types&lt;/strong&gt;&lt;br&gt;&#xA;Spark plug gasket probes can read higher than &quot;normal&quot; cylinder head probes, so if gasket probes were used on cylinders 1, 3, and 4 and a standard bayonet probe used on #2 that would account for the difference.&lt;br&gt;&#xA;(I can't see why this would be the case though: usually you have one gasket probe - on the cylinder where the manufacturer's CHT gauge was connected because it's using the normal bayonet probe hole - and bayonet probes in the rest, not the other way around.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;A mixture imbalance&lt;/strong&gt;&lt;br&gt;&#xA;Cylinder #2 is running richer or leaner than the other cylinders. &#xA;Since you say the engine is not running rough Cylinder #2 would probably be running rich.  (This is normally something you'd notice with Exhaust Gas Temperature rather than Cylinder Head Temperature.)&lt;br&gt;&#xA;You can check for this by watching the engine monitor as you lean the engine: Cylinder #2's &lt;em&gt;EGT&lt;/em&gt; will peak at a different time than the rest of the cylinders (early = leaner, late = richer). On fuel-injected engines this can be adjusted for by using tuned injector nozzles. On carbureted engines you just have to live with it - but at least you'll know the cause and be able to determine what &quot;normal&quot; is for this engine.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Fouled/Failed Spark Plug&lt;/strong&gt;&lt;br&gt;&#xA;Easy to check in-flight: Cycle each magneto; If the cylinder dies on one you've found the culprit.&lt;br&gt;&#xA;(Something you should probably catch on your preflight mag check too.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;A cooling problem&lt;/strong&gt;&lt;br&gt;&#xA;If the cooling baffles for your engine are worn/damaged/incorrectly positioned you might have anomalous airflow that's directing more cooling air over the #2 cylinder head than the rest of the cylinders.&lt;br&gt;&#xA;(Normally you find baffle problems because one or more cylinders are running &lt;em&gt;hot&lt;/em&gt;, but cold is possible too.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;A cylinder problem&lt;/strong&gt;&lt;br&gt;&#xA;An exhaust valve that's not fully closing can cause low CHTs - your mechanic can confirm this with a borescope (or a compression test -- they'll hear air escaping through the exhaust if the valve isn't closing).&lt;br&gt;&#xA;If this is the case it's something to attend to, because if it's ignored it can lead to &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Air-Safety-Institute/Valve-Safety&quot; rel=&quot;noreferrer&quot;&gt;an exhaust valve failure&lt;/a&gt;, which can ruin your day.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2014-12-30T05:30:29.647" LastActivityDate="2014-12-30T05:30:29.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11426" PostTypeId="1" CreationDate="2014-12-30T06:28:24.740" Score="2" ViewCount="317" Body="&lt;p&gt;How is accuracy achieved in Inertial Positioning?  Is it possible to get 10 or 11 digits of accuracy without transmission of real-time corrections from a base (&lt;strong&gt;known&lt;/strong&gt;) station? Is post-processing simultaneous data of Ref. &amp;amp; Rover required for getting the precise (10 &amp;amp; 11 digit) coordinates?&lt;/p&gt;&#xA;" OwnerUserId="5663" LastEditorUserId="1696" LastEditDate="2016-07-06T21:48:17.010" LastActivityDate="2016-07-06T21:48:43.213" Title="How accurate is inertial positioning?" Tags="&lt;navigation&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2014-12-30T13:13:44.163" ContentLicense="CC BY-SA 3.0" />
  <row Id="11427" PostTypeId="2" ParentId="11416" CreationDate="2014-12-30T08:50:14.590" Score="9" Body="&lt;p&gt;I was once passenger/safety-pilot in a Cessna 150 where the gasket between the tank and the wing skin had failed. Looked over my shoulder before the first turn onto crosswind and discovered that the rear windshield was utterly covered in fuel - easily a couple of litres a minute. And that was with the cap firmly in place (the first thing we checked after shutdown!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was a long time ago, but I think the engineers said it had been sucked out through the flap tracks and we probably had a wingful of fuel vapour. Nice...&lt;/p&gt;&#xA;" OwnerUserId="2514" LastActivityDate="2014-12-30T08:50:14.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11428" PostTypeId="2" ParentId="11426" CreationDate="2014-12-30T09:21:53.087" Score="1" Body="&lt;p&gt;Rather than talking to (a single) base station, most aviation units will use signals from additional satellites to apply corrections.  In North America, the system is WAAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a standard (civilian, single-frequency) GPS unit, the largest contributor to the positional error is the ionosphere model used. (See &lt;a href=&quot;http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_Positioning_System&quot; rel=&quot;nofollow&quot;&gt;GPS Error Analysis&lt;/a&gt; page).     WAAS transmits data that allows the unit to apply a real-time correction to that model for locations over North America.  (Similar systems exist to do the same in other regions of the world).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Actual performance measurements of the system at specific locations have shown it typically provides better than 1.0 metre (3 ft 3 in) laterally and 1.5 metres (4 ft 11 in) vertically throughout most of the contiguous United States and large parts of Canada and Alaska.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="1696" LastEditDate="2016-07-06T21:48:43.213" LastActivityDate="2016-07-06T21:48:43.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11429" PostTypeId="2" ParentId="11426" CreationDate="2014-12-30T10:34:51.173" Score="3" Body="&lt;h1&gt;&quot;Inertial GPS&quot;&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Inertial navigation is separate from GPS navigation. Inertial navigation senses accelleration and uses that to estimate changes in velocity and hence estimate changes in position. GPS is a GNSS system that determines position from timing of satellite signals. There's no such thing as Inertial GPS although there are systems marketed as sat-nav which can use inertial navigation when GPS is unavailable (e.g. when driving through a tunnel).&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;10th Character&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Digits are about precision not accuracy. Any sat-nav or GNSS receiver can produce location digits to much greater precision than their accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number of digits, and their implications regarding accuracy and precision, depends on the units being presented. For example, I have a handheld GNSS receiver that I set to display UK Grid-references for convenience in conjunction with Ordnance Survey maps. The meaning of the 10th and 11th characters in terms of positional precision is therefore different.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;TQ&#xA;395012&#xA;775012&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;In this case, the 10th digit is something like kilometers north of the OS origin. Accuracy of ±1 Km can certainly be achieved by unaugmented GNSS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is probably better to state a desired accuracy in terms of distance on the ground - for example many handheld GNSS receivers will display something like &quot;Accuracy: 23 feet&quot;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Base stations&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;All GNSS receivers (including GPS, GLONASS, Galileo etc) use multiple satellites to determine their position. Typically three or four are required for a fix. Pure GNSS receivers don't use base stations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SBAS capable receivers (such as those that can use WAAS, EGNOS, etc) use additional satellites to achieve higher accuracy. They do not directly use base stations on the ground. The additional satellites transmit positional corrections that have been gathered from ground stations but the GNSS receivers do not receive data directly from the ground stations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Higher accuracy GNSS units are used by, for example, site surveyors. These are larger and more expensive and in some cases do use ground base stations for greater accuracy.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aviation&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Generally, I don't think aviators have any use for knowing their aircraft location to centimeter accuracy in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A GNSS with SBAS (e.g. GPS + WAAS) can provide the accuracy needed for  precision flight approaches but &lt;a href=&quot;http://www8.garmin.com/aboutGPS/waas.html&quot; rel=&quot;nofollow&quot;&gt;Garmin state&lt;/a&gt; &lt;em&gt;&quot;Currently, GPS alone does not meet the FAA's navigation requirements for accuracy, integrity and availability&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Glossary&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GNSS = Global Navigation Satellite System.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GPS = Global Positioning System, US operated GNSS.&lt;/li&gt;&#xA;&lt;li&gt;Galileo = EU operated GNSS.&lt;/li&gt;&#xA;&lt;li&gt;GLONASS = Global Navigation Satellite System, Russian operated GNSS.&lt;/li&gt;&#xA;&lt;li&gt;BDS = BeiDou Navigation Satellite System, China operated GNSS. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;SBAS = Satellite Based Augmentation Systems.&#xA;&lt;ul&gt;&#xA;&lt;li&gt;WAAS = Wide Area Augmentation System = US operated SBAS.&lt;/li&gt;&#xA;&lt;li&gt;EGNOS = European Geostationary Navigation Overlay Service, EU SBAS.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;GBAS = Ground Based Augmentation Systems.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2014-12-30T11:14:00.477" LastActivityDate="2014-12-30T11:14:00.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11430" PostTypeId="1" AcceptedAnswerId="11433" CreationDate="2014-12-30T10:49:14.563" Score="18" ViewCount="2582" Body="&lt;p&gt;A Boeing 747-400 recently made an emergency landing without the wheels under the right wing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.bbc.co.uk/news/uk-30625945&quot; rel=&quot;nofollow noreferrer&quot;&gt;News story&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZcEYQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Photo of the undercarriage&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.facebook.com/video.php?v=671587576283197&amp;amp;set=vb.122548417853785&amp;amp;type=2&amp;amp;theater&quot; rel=&quot;nofollow noreferrer&quot;&gt;Video of the landing from the end of the runway&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What's the standard technique for carrying out such a landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What might go wrong? Does it require more runway? Is there a significant risk of dragging one wing on the ground?&lt;/p&gt;&#xA;" OwnerUserId="704" LastEditorUserId="1918" LastEditDate="2014-12-30T21:53:12.627" LastActivityDate="2014-12-31T01:04:35.903" Title="What's the technique for landing without one set of wheels?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11431" PostTypeId="1" AcceptedAnswerId="11465" CreationDate="2014-12-30T11:22:46.040" Score="17" ViewCount="1325" Body="&lt;p&gt;How do you perform a gear-up landing in a large airliner (say, a Boeing 747)?  Would you fly it like a normal landing, or are there special considerations (angle of touchdown, use/non-use of thrust reversers, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="572" LastEditDate="2015-02-24T10:42:51.080" LastActivityDate="2015-02-24T10:42:51.080" Title="How do you perform a gear-up landing in a large airliner?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11432" PostTypeId="2" ParentId="11422" CreationDate="2014-12-30T14:41:51.870" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Plywood sheets can penetrate tree trunks unscathed&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The plywood isn't unscathed by the process&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OkRjE.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why wouldn't an airplane [be unscathed by] impacting ocean water at a steep angle at 300-500 mph?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aircraft will not travel at that same speed underwater. That means that a considerable force is applied to the aircraft to decelerate it in a short distance. That force greatly exceeds what the structure was designed for.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2014-12-30T14:41:51.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11433" PostTypeId="2" ParentId="11430" CreationDate="2014-12-30T15:33:43.470" Score="23" Body="&lt;p&gt;The techniques vary slightly aircraft to aircraft, and also based on what landing configuration you have.  However, the general gist is to hold off the malfunctioning side from the runway for as long as possible, slowing the aircraft in the process, until forced to put it down on the deck.  This minimizes the contact between the wings and/or fuselage with the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The single greatest danger with these types of landings is the risk of fire. The friction between the runway surface and the aircraft is tremendous generating an enormous amount of heat.  This is particularly problematic when you consider that the fuel is stored in the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel may be pumped to the opposite wing to counter-balance weight and move the fuel away to the fuselage with the highest possibility to have contact with the ground. This technique will shift weight away from the missing wheels and consequently reduce the possibility of fire.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="-1" LastEditDate="2014-12-31T01:04:35.903" LastActivityDate="2014-12-31T01:04:35.903" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11434" PostTypeId="2" ParentId="11412" CreationDate="2014-12-30T15:35:22.817" Score="10" Body="&lt;p&gt;According to the tooltips on the Lockheed Martin site, the flight rules are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;MVFR - Military VFR; restricted to military flights&lt;/li&gt;&#xA;  &lt;li&gt;MIFR - Military IFR; restricted to military flights&lt;/li&gt;&#xA;  &lt;li&gt;YFR - Initially operated under IFR, followed by one or more changes of flight rules&lt;/li&gt;&#xA;  &lt;li&gt;ZFR - Initially operated under VFR, followed by one or more changes of flight rules&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's very little information on MVFR and MIFR flight plans that I could find, but the FAA's FSS procedures do include &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/fss/fss0604.html&quot;&gt;specific actions&lt;/a&gt; that are required when receiving a military flight plan (section 6-4-7).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;YFR and ZFR are ICAO rules; the FAA calls combined VFR/IFR flight plans &lt;em&gt;composite flight plans&lt;/em&gt; (see &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0501.html&quot;&gt;section 5-1-7&lt;/a&gt; in the AIM) and on a US domestic composite flight plan both VFR and IFR should be checked. Interestingly, the Lockheed Martin site doesn't allow that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2014-12-30T15:35:22.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11436" PostTypeId="1" CreationDate="2014-12-30T19:01:17.930" Score="3" ViewCount="144" Body="&lt;p&gt;I was computing the hypothetical profitability of commercial airline flights and it seems to be pretty extreme. For example, looking at the Boston-DCA shuttle, pro-rating all costs to the just the flight itself using conservative figures I came up with the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;aircraft: A320&lt;br&gt;&#xA;distance: 346 nautical miles&lt;br&gt;&#xA;fuel usage: 6500 pounds&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;fuel: 3800&lt;br&gt;&#xA;maintenance: 2000&lt;br&gt;&#xA;crew: 1200&lt;br&gt;&#xA;hangar: 900&lt;br&gt;&#xA;insurance: 400&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total costs: 8,300&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;passenger count: 150&lt;br&gt;&#xA;ticket charge: 200&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total revenue: 30,000&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on these figures, profitability of this route seems to be about 350%, i.e., more than tripling your costs on every flight. Even if we allow for tickets of $100 each, it is still almost a 100% profit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I missing something, or are these figures in the right ballpark?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;THIS IS NOT A DUPLICATE OF &lt;a href=&quot;https://aviation.stackexchange.com/questions/654/whats-the-typical-cost-and-its-breakdown-for-a-long-haul-commercial-flight&quot;&gt;long-haul flight costs&lt;/a&gt;. That post is for LONG HAUL flights. This is a shuttle. That post concerns a completely different aircraft with costs amortized ANNUALLY. This is post is about PER-FLIGHT profitability, not ANNUAL profitability.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ALSO: This post asks about PROFITABILITY on this route, not just costs. It includes REVENUE.&lt;/strong&gt; I am not asking general profitability; I am asking about this calculation for profitability on the route in question using the aircraft in question (A320).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2014-12-30T21:41:11.560" Title="How profitable is an airline shuttle flight between BOS and DCA on an A320?" Tags="&lt;airline-operations&gt;&lt;economics&gt;" AnswerCount="0" CommentCount="10" ClosedDate="2014-12-30T20:48:13.997" ContentLicense="CC BY-SA 3.0" />
  <row Id="11437" PostTypeId="2" ParentId="9242" CreationDate="2014-12-30T22:03:05.217" Score="7" Body="&lt;p&gt;Most of the primary reasons are already covered here, but another reason can simply be availability. This is part of the reason cited for Delta's recent choice to order A350s and A330neos rather than more 787s. While &lt;a href=&quot;http://en.wikipedia.org/wiki/Delta_Air_Lines_fleet#Current_fleet&quot;&gt;Delta already has 18 787-8s on order&lt;/a&gt;, the lack of availability of additional order slots in the time frame that Delta needed to replace its aging 747s and 767s was, &lt;a href=&quot;http://www.nytimes.com/2014/11/21/business/airbus-wins-delta-order-on-promise-of-delivery.html?_r=0&quot;&gt;according to Boeing&lt;/a&gt;, part of the reason that Delta chose to order A350s and A330neos rather than adding to its existing 787 orders. Additionally, the 777X was also not going to be ready to deliver in the time frame that Delta needed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“This was a long and highly competitive campaign,” said Doug Alder, a Boeing spokesman. “Boeing competed for the order with the 787-9, but we did not have enough 787 positions available in the time frame that met Delta’s requirement.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-12-30T22:03:05.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11438" PostTypeId="1" AcceptedAnswerId="11510" CreationDate="2014-12-30T22:21:59.783" Score="15" ViewCount="12260" Body="&lt;p&gt;That way we could study plane crashes more closely, or terrorist hijackings, or resolve passenger disputes. &lt;a href=&quot;https://www.youtube.com/watch?v=21L4XU5Z-DU&quot; rel=&quot;nofollow&quot;&gt;Even buses in Ecuador have video cameras.(WARNING: shocking video)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="5672" LastEditorUserId="19" LastEditDate="2016-06-22T09:06:45.267" LastActivityDate="2018-06-22T17:36:12.500" Title="Why don't airlines have in-flight video recordings like buses do?" Tags="&lt;aircraft-design&gt;&lt;flight-data-recorder&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11439" PostTypeId="2" ParentId="11438" CreationDate="2014-12-31T00:38:02.470" Score="11" Body="&lt;p&gt;Regarding cabin cameras, there's not much of a need for them. Busses typically don't have flight attendants. In-flight disputes are typically handled well and quickly by the cabin crew on an airliner. Also, theft or assault would have dozens to hundreds of eyewitnesses and no route of escape for the perpetrator, unlike on a bus (which is probably why such incidents are almost completely unheard of on airliners.) In the case of a terrorist hijacking, having video wouldn't really help much. It's usually pretty obvious when an airliner has been hijacked, but there's not a lot that people on the ground can do about it, aside from the possibility of shooting it down if it appears to be threatening a 9/11-style attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding exterior cameras, these are actually starting to appear on some airliners now. Newer airliners like the 777-300ER and the A380, for instance, have them, though I don't think they actually record the video. Even if they did, it seems unlikely that they'd provide any useful information beyond what the FDR data and accident scene examination had already revealed (i.e. they'd basically just show that the plane ran into the ground, which would already be known by the time you found the video.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding cockpit video recording, there is an answer &lt;a href=&quot;https://aviation.stackexchange.com/questions/8546/if-we-add-a-video-recorder-in-the-cockpit-to-complete-fdr-cvr-will-we-add-a-bla/8547#8547&quot;&gt;here&lt;/a&gt; that addresses it. There have been some suggestions for this to be added over the years, but pilots tend to be against it and the additional information it would provide would likely not be particularly useful in most instances, given that we already have a recording of all of the conversations up to the time limit of the recorder as well as the FDR data.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2014-12-31T02:26:32.267" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11440" PostTypeId="1" AcceptedAnswerId="11441" CreationDate="2014-12-31T07:52:11.443" Score="7" ViewCount="10516" Body="&lt;p&gt;In many media reports regarding air incidents such as &lt;a href=&quot;http://www.nbcnews.com/storyline/missing-airasia-plane/airasia-flight-qz8501-what-we-know-about-missing-plane-n276066&quot;&gt;AirAsia Flight QZ8501: What We Know About the Missing Plane&lt;/a&gt; from NBC News I often see a phrase such as the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By the time it had been given clearance, just four minutes after its last correspondence, the jet had disappeared from radar, Tjahjono told the news agency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From various maps I've seen it appears the aircraft went missing over 100 km from any major land masses / airports and it made me wonder how far commercial aircraft would normally be tracked by traditional radar that sends a ping and waits for an echo from a typical airport? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing in many cases media tend to use the term radar interchangeably with transponder technologies such as ACARS but I'd still be interested to know the limits of typical radar installations and how prevalent it remains in modern commercial aviation.&lt;/p&gt;&#xA;" OwnerUserId="3730" LastEditorUserId="97" LastEditDate="2015-04-22T00:34:26.363" LastActivityDate="2015-04-22T00:34:26.363" Title="How prevalent is traditional radar tracking of commercial aircraft?" Tags="&lt;commercial-aviation&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11441" PostTypeId="2" ParentId="11440" CreationDate="2014-12-31T10:13:29.820" Score="10" Body="&lt;p&gt;There are many surveillance technologies available to track aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar is the most common technology used for ATC (Air Traffic Control) surveillance. Basically there are two varieties:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Primary radar&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type of radar sends a high energy radio pulse which reflects of the aircraft. The time delay of the received echo is a measure of the distance.&#xA;The characteristics of the transmitted radio pulse.&lt;br/&gt; Since aircraft don't have to participate for this radar to work this radar principle is mostly used for Air Defence purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC primary radar usually has a maximum range of about 50-100NM, but can exceed 200NM. Primary radar is mostly used for airspace protection (monitoring unauthorized access) and airport surface control. These radars have a limited maximum range but a very low minimum range and provide reasonable accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long range primary radar is expensive to operate. Due to the free space signal loss, long range radar needs to transmit a very powerful pulse and receive an very weak echo. The associated infrastructure (large antenna, active cooling) and power requirements make long range primary radar very expensive. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military use of primary radar includes over the horizion (OTH) radar which has ranges well over 1000NM. These radars are geared towards detection of incoming missiles and aircraft and not suitable for air traffic control due to their lower accuracy.   &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Secondary radar&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondary radar is the most common surveillance technology used by ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type sends a radio signal to the aircraft's transponder to which the transponder replies with its own radio signal. Again the time delay is a measure of the distance. The transponder can encode additional information about the aircraft (such as altitude or identity) in the reply. This radar technology relies on the correct functioning of the radar transponder. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the radar relies on transmission of energy from the aircraft, the transmitter needs less power than a primary radar. The maximum range of secondary radars can exceed 250 NM for aircraft flying high enough (above the horizon). Not all secondary radars are operated at that range though, airport radars are often limited to 50 - 100 NM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v3dnQ.png&quot; alt=&quot;signal horizon&quot;&gt;&#xA;Radar signal horizon&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Then there are a number of surveillance technologies which are a bit different than radar: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;(Wide Area) Multilateration&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This technology uses multiple receivers spread over an area. By accurately comparing the times that an aircraft's transponder signal arrives at the different receivers the system can calculate where the signal must have been transmitted from. The transponder signal must be received by at least four receiver to get an accurate position. The accuracy of multilateration is best in the area surrounded by receivers; outside that area the accuracy of the system degrades quickly. A provide with enough receivers, a Wide Area Multilateration system can cover vast airspace volumes. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;ADS-B&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automatic Dependent Surveillance - Broadcast is a surveillance technology that relies on the aircraft transmitting their position twice per second. A simple antenna and receiver is all that is required to receive these positions. Since the signal comes from the radar transponder, the above signal horizon figure applies. A very sensitive receiver can detect high flying aircraft far away. Not all aircraft are yet equipped with ADS-B but most passenger transport aircraft are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The company Aireon is equipping satellites with ADS-B, so in 2018 there will be oceanic ADS-B coverage.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;ADS-C&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automatic Dependent Surveillance - Contract is again a surveillance technology that relies on the aircraft transmitting their position. Contrary to the broadcast counterpart which transmits to all interesting parties, ADS-C addresses its transmissions to the contracted ATC facility. The data goes via a satellite link or over VHF when the aircraft is flying over land. Because of the satellite link, coverage is global (except the poles).&#xA;ADS-C reports are less frequent that radar or ADS-B reports, typically the system only reports at specific reporting points. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-C is not installed on every aircraft, mostly on intercontinental transport aircraft. It is used mainly over the Pacific and the Atlantic. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Verbal position reporting&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not really a surveillance technology, but used in areas where there is no other means of surveillance available. The pilot reports his position over the radio to air traffic control. The maximum range of the radio transmission is the limiting factor here. Using HF radio, global coverage is achievable. The transmissions suffer a lot from static noise and sometimes other aircraft have to relay messages if no proper direct communication between ATC and the aircraft can be achieved. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2014-12-31T10:27:49.160" LastActivityDate="2014-12-31T10:27:49.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11442" PostTypeId="1" AcceptedAnswerId="11447" CreationDate="2014-12-31T13:01:14.000" Score="10" ViewCount="1737" Body="&lt;p&gt;I recognise the &lt;a href=&quot;http://www.dailymail.co.uk/travel/travel_news/article-2890163/United-Airlines-captain-aborts-transatlantic-journey-diverts-plane-Heathrow-additional-icing-just-90-minutes-taking-Brussels.html&quot; rel=&quot;noreferrer&quot;&gt;Daily Mail&lt;/a&gt;'s propensity to adulterate and colour news, but are these user comments about the &lt;a href=&quot;http://avherald.com/h?article=47f7c452&amp;amp;opt=0&quot; rel=&quot;noreferrer&quot;&gt;UAL951 flight on 29 Dec 2014&lt;/a&gt; correct?&lt;/p&gt;&#xA;&lt;p&gt;The Daily Mail claims:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A United Airlines plane aborted its transatlantic journey and diverted to London today because the flight crew apparently wasn’t satisfied with the de-icing effort it received in Brussels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;But some commenters under the article regard this official reason as concealment or falsehood:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dailymail.co.uk/reader-comments/p/comment/link/72509725&quot; rel=&quot;noreferrer&quot;&gt;If the de-icing job wasn't good the plane would have crashed on take off. There must be more to this story.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dailymail.co.uk/reader-comments/p/comment/link/72601827&quot; rel=&quot;noreferrer&quot;&gt;Correct. If the de-icing was not done correctly, the aircraft would have crashed on take-off. Since it was able to fly, climb to cruise altitude and travel several hundred miles, no further de-icing would be required. There was some other unreported reason for the diversion.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Is there any truth in these claims? Will an aircraft crash on take-off if the de-icing is not done correctly?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-04T17:08:52.907" Title="Will an aircraft always crash on take-off if de-icing is not performed correctly?" Tags="&lt;safety&gt;&lt;ground-operations&gt;&lt;incidents&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11443" PostTypeId="1" AcceptedAnswerId="11484" CreationDate="2014-12-31T13:07:47.543" Score="30" ViewCount="10746" Body="&lt;p&gt;Especially during turbulence, I notice that passengers are warned to sit and fasten seatbelts, but flight attendants continue to serve only cold beverages (since the overflow, slosh, spill of hot beverages would be dangerous), stand, walk, and work. Why? It appears unfair for flight attendants to suffer any more risk and danger, even if the turbulence is minor, than passengers. &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="128" LastEditDate="2016-11-08T16:27:58.873" LastActivityDate="2016-11-08T16:27:58.873" Title="Why do flight attendants continue to stand, when the seatbelt sign is on?" Tags="&lt;flight-attendant&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11444" PostTypeId="2" ParentId="11443" CreationDate="2014-12-31T13:14:34.940" Score="30" Body="&lt;p&gt;Flight attendants are quite used to minor turbulence. The average passenger is not, and could easily end up somewhere uncomfortable. Turbulence also has the habit of getting worse without too much warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAs &lt;em&gt;do&lt;/em&gt; buckle up once the turbulence reaches a certain level. I once departed Hong Kong during a typhoon - the FA sitting across from me said the crew was told to stay seated for 20 minutes after takeoff, and she'd never heard that instruction before.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2014-12-31T13:14:34.940" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11445" PostTypeId="2" ParentId="11438" CreationDate="2014-12-31T13:22:37.620" Score="10" Body="&lt;p&gt;Note that cameras are already installed in some aircraft; but I believe this is an operator option and not standard equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, from this &lt;a href=&quot;https://www.gcaa.gov.ae/en/ePublication/admin/iradmin/Lists/Incidents%20Investigation%20Reports/Attachments/55/2014-Final%20Report%20-%20A6-FEK,%20AAIS%20Case%20No.%200008-2014.pdf&quot;&gt;incident report of a 737-800&lt;/a&gt; PDF:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The captain stated that he could see on the cabin observation camera&#xA;  screen in the cockpit that a CCM was wearing personal breathing&#xA;  equipment (PBE). The captain switched off the IFE. This action also&#xA;  switched off the camera since the IFE and the camera are on the same&#xA;  electrical bus.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2014-12-31T13:22:37.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11446" PostTypeId="2" ParentId="11443" CreationDate="2014-12-31T13:24:19.970" Score="30" Body="&lt;p&gt;It's about risk management. In minor turbulence, probably nothing bad will happen so it's OK to have a few people walking around but, in the unlikely event of a big bump, you don't want to have 300 passengers thrown around the plane. If the turbulence is bad enough, even the flight attendants sit down and put their seatbelts on.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-12-31T13:24:19.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11447" PostTypeId="2" ParentId="11442" CreationDate="2014-12-31T13:48:47.047" Score="23" Body="&lt;p&gt;The claim that de-icing must have been done perfectly in Brussels or the plane would have crashed on take-off is patent nonsense. Ice on the aircraft degrades performance. A little bit of ice degrades performance a little bit; a lot of ice degrades performance a lot. It's perfectly possible that they took off from Brussels with slightly degraded performance, realised that there was still some ice on the plane and decided they needed to get rid of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no reason to suspect a cover-up. If there was even a hint of terrorism, the plane would have diverted to Stansted, not Heathrow. If the plane had some mechanical problem, they'd have made a vague statement about the plane having mechanical problems, landed, fixed the problem (which requires maintenance technicians, not a de-icing crew), and then said something much less vague to reassure the 227 passengers that the plane was safe. If there was a problem with the passengers, luggage or cargo, the plane would have gone to a terminal. If a vice-president of the company had been served macadamia nuts in the wrong way, they'd have dealt with that in Brussels.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2014-12-31T13:48:47.047" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11448" PostTypeId="2" ParentId="11443" CreationDate="2014-12-31T15:29:13.537" Score="22" Body="&lt;p&gt;In the U.S., the Federal Aviation Regulations (FARs,) specifically &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/121.317&quot;&gt;14 CFR 121.317&lt;/a&gt;, only require that passengers be seated when the seat belt sign is on, not the crew.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(f)  Each passenger required by § &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/121.311#b&quot;&gt;121.311(b)&lt;/a&gt; to occupy a seat or berth shall fasten his or her safety belt about him or her and keep it fastened while the “Fasten Seat Belt” sign is lighted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is primarily for the reasons mentioned in paul and David Richerby's answers, namely, that the cabin crew is trained and experienced in walking through the cabin in light to moderate turbulence and that have 3 or 4 unsecured people is much less of a risk than 150 unsecured people. The very slight risk of a cabin crew member being injured during light to moderate turbulence is not seen to outweigh the benefit of cabin crew being able to continue performing their duties. As paul and David mentioned, the flight crew will still advise the cabin crew to be seated during take-off, landing, and more severe turbulence. For instance, in my experience at least, it seems that the cabin crew is usually advised to take their seats as the aircraft is entering or crossing a jet stream or operating near thunderstorms.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-01-02T17:20:53.677" LastActivityDate="2015-01-02T17:20:53.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11449" PostTypeId="1" AcceptedAnswerId="11451" CreationDate="2014-12-31T19:28:46.517" Score="25" ViewCount="69154" Body="&lt;p&gt;This is from the &lt;a href=&quot;http://gofar.aircanada.com/up-in-the-air/ask-pilot-polar-routes/&quot;&gt;last paragraph here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... no aircraft crosses directly over the pole – the closest route is&#xA;  60 nautical miles (nm) away.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;User Michael Shen of York University asked this originally under the article. &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="19" LastEditDate="2016-11-15T14:32:29.050" LastActivityDate="2017-08-12T02:25:02.183" Title="Why does &quot;no aircraft cross directly over the pole&quot;?" Tags="&lt;navigation&gt;&lt;polar&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11450" PostTypeId="2" ParentId="11422" CreationDate="2014-12-31T21:40:40.017" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Has the outcome of such an event ever been demonstrated?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The outcome of an aircraft flying nose-first into water has been demonstrated an unfortunately-large number of times. And it doesn't end well for the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The situations you're describing are very different. The physics of a plywood sheet penetrating the trunk of a tree happen because of the extremely high winds. When the wind is 150 mph (and parallel to the board,) the path of least resistance may very well be straight through the tree. Any deflection of the board to one side or the other would increase its cross-sectional area relative to the wind and, thus, would be countered by the force of the wind itself. If you were to otherwise attempt to fire a plywood board into a tree (in the absence of wind,) I think you'd find quite different results (though not quite as different as the aircraft impacting water scenario.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the physics of flying an aircraft nose-first into water at 300-500 mph differ only slightly from those of flying an aircraft nose-first into the ground at 300-500 mph. In the first few seconds, the water will displace somewhat more than the ground would have, but not much. It takes a lot of force to accelerate the water to the sides quickly enough for it to be displaced by the aircraft at 300-500 mph and, since the force is applied equally (but opposite in direction) to both the aircraft and the water, the forces applied to the aircraft will be plenty to destroy it very quickly. The pieces of the aircraft will continue to lose speed until either they're floating on top of the water (for pieces that are less dense than water) or are sinking at their terminal velocity into the water (which will be quite slow in water.) Meanwhile, all of the kinetic energy of the aircraft is being dissipated very quickly into doing things like crushing the airframe and/or ripping it apart, accelerating water out of the path of the aircraft, heating up the water and (more so) the aircraft, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as why the forces would be enough to crush the aircraft (as opposed to what would happen if you fired a long, narrow, cylindrical chunk of solid aluminum into the water at the same angle and speed,) the aircraft is relatively hollow. The cross-sectional area impacting the water is much greater for an aircraft than for a cylinder of solid aluminum of equal mass and length, which means that a much higher total force will be applied to it (similar pressure, but integrated over a much larger surface area.) Furthermore, since a solid chunk of aluminum is a bit more dense than the air that fills most of the cabin of an aircraft, the aircraft would be more apt to crush. The portion of the hull impacting the water would be accelerated into the space behind it, since the forward force being applied to it by the contents of the cabin and the more aft portions of the hull would be much smaller than the backward force being applied to it by the water it's impacting. That is to say, the hull would be crushed very much like an aluminum can. When you stomp on an aluminum can with your shoe, the can crushes rather than penetrating your foot (at least you hope so...) This situation is much more analogous to an aircraft ramming into water than the case of plywood in a hurricane encountering a tree that you mention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, as others have mentioned, the reason that the plywood can actually exit the tree is just that it doesn't get slowed down completely to a stop by the collision and friction with the tree as it's entering the tree. For a sufficiently-narrow tree, this allows it to exit the other side before it's completely stopped. However, for a sufficiently-thick tree, the situation would be largely unchanged except that the leading edge of the board would stop somewhere inside the tree.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2014-12-31T21:40:40.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11451" PostTypeId="2" ParentId="11449" CreationDate="2014-12-31T22:56:55.743" Score="38" Body="&lt;p&gt;&lt;a href=&quot;http://hub.aa.com/en/cl/north-america-chicago-asia&quot;&gt;This article from AA&lt;/a&gt; (titled &quot;Over the Top&quot; by Gerard J. Arpey) says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By the way, because of the limitations of older navigation systems, none of the polar routes we fly crosses exactly over the North Pole. At the Pole, an airplane’s compass changes from a due-north heading to due south, and that change of course could potentially lead to problems with ­earlier-generation autopilot systems. Fortunately, that is not an issue with the latest generation of long-haul aircraft, such as the Boeing 777s we fly, whose source of navigation is the extremely precise Global Positioning System (GPS). Nonetheless, to make polar flying equally effortless for both the new generation and the previous generations of aircraft, &lt;strong&gt;none of the approved civil polar routes comes closer than about 60 nautical miles from the Pole&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="556" LastActivityDate="2014-12-31T22:56:55.743" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11452" PostTypeId="1" CreationDate="2015-01-01T02:29:29.020" Score="16" ViewCount="1099" Body="&lt;p&gt;There have been may cases of civilian, commercial, and military flights that have either been forced to or accidentally landed gear up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When this happens I imagine that it can do serious damage to the runway it's landing on (assuming it's landing on a paved runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the runway need to be repaired after such a landing, if so, how long does it take, and how extensive are the repairs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are some of the different scenarios that come to mind:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Civilian aircraft doing a gear up landing, maybe about 1500-5000lb or so.&lt;/li&gt;&#xA;&lt;li&gt;Commercial airliner doing a full gear up landing.&lt;/li&gt;&#xA;&lt;li&gt;Commercial airliner with a single broken wheel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How would runway repair be conduced in these scenarios? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nAs5V.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2015-01-02T06:03:42.923" LastActivityDate="2015-01-02T15:25:24.593" Title="Do runways need to be repaired after gear up landings?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11455" PostTypeId="2" ParentId="11449" CreationDate="2015-01-01T06:41:08.673" Score="13" Body="&lt;p&gt;Until recently, regulators have insisted that twin-engine jets must always be within three hours of a suitable place to land. This is because the failure of one engine on such a plane is potentially far more serious than for one with three or four.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, commercial flights do fly over the North Pole. For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://uk.flightaware.com/live/flight/UAE215&quot;&gt;a number of flights&lt;/a&gt; that flies between US and Asia will fly over the North Pole&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://gc.kls2.com/cgi-bin/gc?PATH=DEL-DEN&quot;&gt;Denver to Delhi&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is possible to fly over South Pole as well. In 1977, PanAm 747Sp flew over South Pole while flying from Sydney to Recife. However, South Pole does not lie on the great circle route for too many points.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="65" LastEditDate="2015-01-02T16:12:25.577" LastActivityDate="2015-01-02T16:12:25.577" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11456" PostTypeId="1" AcceptedAnswerId="11463" CreationDate="2015-01-01T09:25:54.073" Score="36" ViewCount="6425" Body="&lt;p&gt;There are a number of airports above &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_highest_commercial_airports&quot;&gt;8000 ft altitude&lt;/a&gt;. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8500c800f7148711696c29a64638db23&amp;amp;node=se14.1.25_1841&amp;amp;rgn=div8&quot;&gt;FAR 25.841&lt;/a&gt; states: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet at the maximum operating altitude&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does an airliner operating from a high airport, say from &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Dorado_International_Airport&quot;&gt;El Dorado&lt;/a&gt;, deal with cabin pressure? Do they actually &lt;em&gt;pressurize&lt;/em&gt; the cabin after takeoff and &lt;em&gt;depressurize&lt;/em&gt; it after landing? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: the answer can be of any jurisdiction though FAA seems relevant here as US airlines operate from there.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="65" LastEditDate="2015-01-02T19:48:58.033" LastActivityDate="2015-01-02T20:57:22.947" Title="How does an airliner deal with cabin altitude at an airport above 8000 ft?" Tags="&lt;airline-operations&gt;&lt;cabin-pressure&gt;&lt;high-altitude&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11457" PostTypeId="2" ParentId="11411" CreationDate="2015-01-01T11:44:12.013" Score="4" Body="&lt;p&gt;After a brief search I found an &lt;a href=&quot;http://www.google.co.uk/patents/US4975696&quot; rel=&quot;nofollow&quot;&gt;old US patent&lt;/a&gt; that states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The video display system of the aircraft is directed by the present invention to automatically display aircraft ground speed, outside temperature, and altitude, among other information of interest, as sensed by the aircraft's navigation and air data systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Hence I believe the information comes from same system that the pilots use, though the actual implementation may not be known to any of us outside companies that produce those IFEs.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="97" LastEditDate="2015-01-01T20:56:01.980" LastActivityDate="2015-01-01T20:56:01.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11458" PostTypeId="2" ParentId="11452" CreationDate="2015-01-01T11:57:28.577" Score="10" Body="&lt;p&gt;Runways are usually made of several feet of reinforced concrete. Any damage to them after a wheels-up landing is superficial at best. Details depend on circumstances, but in general light aircraft will cause less damage. A full wheels-up landing is rather easy on the runway: The aircraft's fuselage and wing fairing structure are flexible and malleable, so it will buckle and bend until the local surface pressure is too low to cause more bending. To really damage a concrete surface you would need carbide tools, not sheet aluminum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;a href=&quot;https://www.youtube.com/watch?v=-HyBjwI7aps&quot; rel=&quot;noreferrer&quot;&gt;unwheeled landing gear strut of an airliner&lt;/a&gt; is probably the worst scenario. The Airbus in the linked video had only a damaged nose gear, which carries a small fraction of the total load, and you will see in the close-up at the end of the video that the runway did not suffer. A similarly damaged main gear, however, will cut a groove. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All what is needed for repair is some &lt;a href=&quot;http://www.elastomer.com/polymer/bulletins/gatewayairport/gatewayairport.html&quot; rel=&quot;noreferrer&quot;&gt;fast-curing liquid&lt;/a&gt; for filling the nicks and scratches and some paint to repair the runway markings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you land a composite aircraft wheels-up, the concrete will act like sandpaper on the structure. The landing zone will be marked by white epoxy dust. A broom is all what is needed to put the strip back to its initial condition.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-02T15:25:24.593" LastActivityDate="2015-01-02T15:25:24.593" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11459" PostTypeId="2" ParentId="11456" CreationDate="2015-01-01T13:23:31.160" Score="3" Body="&lt;p&gt;I've been waiting for an answer, but none forthcoming - so - this is GUESSWORK :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin altitude cannot be anything except the ambient altitude when the doors are opened before takeoff and after landing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For landing, the cabin altitude would therefore be set to the airport altitude.  It cannot be anything else since there are valves which automatically prevent negative internal pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For takeoff, my guess is that the cabin altitude would be set to normal according to SOPs for the aircraft and type of flight.  If the departure field was at a higher altitude, then this would result in an increase in cabin pressure.  Otherwise, the normal reduction in pressure would take place.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-01T13:33:27.777" LastActivityDate="2015-01-01T13:33:27.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11460" PostTypeId="2" ParentId="11456" CreationDate="2015-01-01T13:48:36.327" Score="9" Body="&lt;p&gt;The verbiage of the CFR is important (imagine that). The part you quote is really saying the following: if you want to fly an airplane which is equipped with a pressurization system, then, when the airplane is at its maximum operating altitude, the system must be &lt;em&gt;able&lt;/em&gt; to keep the cabin pressure at or below 8,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowhere in the reg you quoted is there anything about maintaining 8,000 feet, and in fact upon landing the dump valves will open and the cabin will depressurize to whatever the ambient pressure is anyway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;I imagine that airline crews would pressurize for passenger comfort until descent, and then gradually bleed away cabin pressure until touchdown.&lt;/strike&gt; The aircraft will maintain 8000 feet until touchdown and then depressurize. Thanks @Kevin!&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2015-01-01T18:39:48.547" LastActivityDate="2015-01-01T18:39:48.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11461" PostTypeId="2" ParentId="11422" CreationDate="2015-01-01T14:33:27.493" Score="5" Body="&lt;p&gt;The plywood was like a cleaver blade hitting the tree. Lots of relatively dense mass and momentum concentrating on a very thin edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane wing (let alone fuselage) is not a thin edge. It is blunt, rounded, and thick. Behind that edge is a low mass and low density object. For the size, aircraft are very light weight and are a carrying a tiny fraction of the momentum a solid (non hollow) aluminum object of the same shape and volume would carry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that plywood wasn't a solid material but rather was hollow like an airplane (thus reducing it's mass, momentum, and consequentially the force acting on the tree), we'd probably see the tree intact and shattered remains of the plywood on the ground.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-01-01T14:33:27.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11462" PostTypeId="2" ParentId="11456" CreationDate="2015-01-01T15:01:36.420" Score="15" Body="&lt;p&gt;I am an aerospace engineer, who has worked on the design and certification of pressurized aircraft, so let me try and answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The class of regulations that deals with the certification of pressurized aircraft are called &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c3af63f3ef77775654e7eb6fc5f94287&amp;amp;node=se14.1.23_1841&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 23.841&lt;/a&gt; (General Aviation) and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=efbdf06c7ef3c3702b88693040eb43cc&amp;amp;node=se14.1.25_1841&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.841&lt;/a&gt; (Commercial). Both paragraphs are pretty much identical and in summary say the following (paraphrasing):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All GA and commercial aircraft designed and certified to cruise at&#xA;  altitudes greater than 25000 ft &lt;strong&gt;must&lt;/strong&gt; be pressurized.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that aircraft whose maximum altitude (often referred to as &quot;service ceiling&quot;) is less than 25000 feet do not have to be pressurized (once you exceed 14000 feet, most people begin to use supplemental oxygen, but above 25000 feet your plane must be pressurized and that's what provides your supplemental oxygen).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unpressurized GA aircraft routinely operate at altitudes up to 25000 feet. This should answer what pressurization an airliner must provide at high-altitude airports: None! Not unless said airport was above 25000 feet would some pressurization be required (a problem that does not exist on this planet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What paragraphs 23.841 and 25.841 are saying is that those airplanes that are pressurized, must be capable of providing cabin altitude of no more than 8000 feet at &lt;em&gt;their&lt;/em&gt; operating altitudes. So consider two aircraft, one operating at 25001 ft and the other at 45000 ft. Both must provide no less than 8000 feet in the cabin. It shouldn't come as a surprise that the one operating at 45000 ft will require a stouter (i.e. stronger and thus heavier) fuselage as the pressure difference between the cabin and outside is much greater. Many modern commercial airliners provide a 5000 feet cabin altitude and some bizjet manufacturers are already considering sea-level pressure in the cabin, but I digress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I hope this sheds some light on this mystery. Cheers.&lt;/p&gt;&#xA;" OwnerUserId="5688" LastEditorUserId="65" LastEditDate="2015-01-02T19:59:12.220" LastActivityDate="2015-01-02T19:59:12.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11463" PostTypeId="2" ParentId="11456" CreationDate="2015-01-01T15:59:29.223" Score="31" Body="&lt;p&gt;Here is the text extracted from Boeing's 777 Flight Crew Operations Manual:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In cabin altitude controller cruise mode, maximum cabin altitude is 8,000 feet. When the takeoff field elevation is higher than 8,000 feet, the cabin &lt;strong&gt;&lt;em&gt;descends&lt;/em&gt; to the cabin cruise altitude while the airplane is climbing&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;When the destination airport elevation is greater than 8,000 feet, cabin altitude controller cruise mode &lt;strong&gt;maintains a cabin altitude of 8,000 feet&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;(...)&lt;/p&gt;&#xA;&lt;p&gt;At touchdown, the outflow valves open to depressurize the cabin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Therefore, when the airplane is on the ground, its cabin altitude is always equal to the ambient altitude. When it is in the air, the maximum is 8000 feet. Whether the cabin altitude will &lt;em&gt;climb&lt;/em&gt; to 8000 feet or &lt;em&gt;descend&lt;/em&gt; to 8000 feet depends on field elevation.&lt;/p&gt;&#xA;&lt;p&gt;The reverse happens upon landing. If landing at an airport at 10,400 feet, the cabin altitude is &amp;lt;= 8000 feet until touchdown, then &lt;em&gt;raises&lt;/em&gt; to 10,400 feet.&lt;/p&gt;&#xA;&lt;p&gt;This make sense - if the outside pressure is greater, how do you open the door? (well with enough force you can, but I will leave it to your imagination as to what happens the moment the door is opened).&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-01T15:59:29.223" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11464" PostTypeId="1" CreationDate="2015-01-01T16:27:42.830" Score="-1" ViewCount="525" Body="&lt;p&gt;Why not engineer a design where in an emergency, the seats turn into a cocoon capable of bouncing on impact and encase the passenger in such a way that impact with the ground will not harm him. of course the seat would have to be built of some new material maybe graphene that is 100's of times stronger than steel and would have to have points of contact with the passenger's body to prevent jarring the body's organs etc. Now cost maybe prohibitive but I think engineers can devise such a seat mechanism that may be light enough but yet strong enough to do the job. is it possible?&lt;/p&gt;&#xA;" OwnerUserId="5689" LastEditorUserId="167" LastEditDate="2015-01-01T19:29:22.423" LastActivityDate="2015-01-01T19:29:22.423" Title="Is it feasible to have passenger jet aircraft seats turn into bouncing cocoons on impact?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-01-01T19:38:40.980" ContentLicense="CC BY-SA 3.0" />
  <row Id="11465" PostTypeId="2" ParentId="11431" CreationDate="2015-01-01T16:47:19.850" Score="16" Body="&lt;p&gt;Assuming that the pilots have tried everything possible and the gear just does not like to come down:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general rule is to find a long runway, touch down as slow as possible. Here are sections extracted from Boeing 777's Flight Crew Training Manual:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Dumping fuel&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If time and conditions permit, reduce weight as much as possible by burning off or jettisoning fuel to attain the slowest possible touchdown speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Elevator&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After touchdown lower the nose gently before losing elevator effectiveness.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Rudder&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At touchdown speed, the rudder has sufficient authority to provide directional control in most configurations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Speedbrakes&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(...) speedbrakes should be extended only when stopping distance is critical. Extending the speedbrakes (...) may compromise controllability of the airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Reverse Thrust&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(...) an engine making ground contact could suffer sufficient damage such that the reverse mechanism may not operate. Selecting reverse thrust (...) may produce an additional asymmetric condition that makes directional control more difficult. Reverse thrust should be used only when stopping distance is critical.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Landing technique&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The technique varies with the combination of failure. If one side of the main gears is missing, land the plane to the side of runway which corresponds to the extended main gear. I.e. if the left gear is down and right gear is up, land on the &lt;em&gt;left&lt;/em&gt; side of the runway instead of centerline. Maintain wings level for as long as possible, and be prepared to brake on the left side to maintain directional control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all the gears decide to hide in the gears bay, land on centerline and use rudder to maintain directional control. Rudder is effective until airspeed drops too low.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;After landing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Evacuate the aircraft as necessary!&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-01T16:47:19.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11466" PostTypeId="2" ParentId="11464" CreationDate="2015-01-01T18:35:34.960" Score="7" Body="&lt;h1&gt;In a word, cost.&lt;/h1&gt;&#xA;&lt;h3&gt;Weight equals cost.&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;How much is this seat going to weigh?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How many paying passengers will not be able to fly because of the added weight of the seats (and the associated cocoon-deploying equipment)?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How much more fuel will the airplane burn to carry all this extra weight?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Design equals cost&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;This super-strong material doesn't exist yet. How much will it cost to invent? Who will pay to develop this material?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How much does the material itself cost? If it's so wonderful why don't we make the whole plane out of it, as every stand-up comic suggests?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How much will the research to perfect and certify the deployment technology cost?&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Passengers panic when the &lt;em&gt;oxygen masks&lt;/em&gt; drop, we can't have the cocoon seats deploying unless there's an actual emergency.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What if there is an actual emergency and the seats &lt;em&gt;don't&lt;/em&gt; work?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;Deployment equals cost&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;How do passengers evacuate the aircraft if they're trapped in cocoons? Do emergency crews have to cut into the structure of the aircraft to get them out?  Now the airplane is destroyed. New airplanes cost money.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What if the aircraft ditches in the Hudson river? Do all the passengers drown? Maybe we should make all the seats eject out of the aircraft. Guess what?  Destroyed aircraft still cost lots of money and &lt;em&gt;now&lt;/em&gt; you've got the extra weight of the ejection devices.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-01T18:51:09.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11467" PostTypeId="2" ParentId="11456" CreationDate="2015-01-01T18:39:27.667" Score="7" Body="&lt;p&gt;In the PC-12, there is a &lt;em&gt;cabin pressurization controller knob&lt;/em&gt; (the lower right-hand knob in the image) that allows you to set the actual altitude at which you are taking off at/climbing or descending to/landing at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Hrgs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you file for FL220. Before departure, you set the  cabin altitude on the dial to 22,000 ft. As the airplane climbs, the engine bleed air pressurizes the cabin until the maximum pressurization differential is reached (shown on the PSI DIFF gauge). The cabin climb rate is shown on the dial in the lower left corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you descend to land, you set the knob to the destination field elevation + 500ft (the lower internal pressure is so you don't blow open the door!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the cabin pressure is 5,000 ft, and you're landing at a field that's 8,000 ft, the cabin will climb even as the aircraft descends. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a failure of the pressurization computer, the pilot can adjust the cabin pressure manually using the knob in the upper righthand corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's fairly simple to operate.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-02T20:57:22.947" LastActivityDate="2015-01-02T20:57:22.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11468" PostTypeId="1" AcceptedAnswerId="11471" CreationDate="2015-01-01T19:18:45.010" Score="10" ViewCount="1801" Body="&lt;p&gt;I'm wondering about the possible lack of real-world flying experience by pilots in non-US carriers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, aspiring airline pilots can work at a variety of jobs, like instructing, towing banners, crop dusting, etc, or part 135, to build time towards the 1250 hours now necessary for a restricted ATP to act as Second In Command (SIC) in carrier operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do non-US pilots who don't have a military aviation background build the hours necessary to obtain an air carrier license in their own country? Are they all ex-military? Do they only need an ICAO-compliant commercial license and not an Air Transport Pilot License (ATPL)? Do we have 250- or 500-hour commercial pilots flying SIC into JFK?  Do these pilots have experience flying non-pushbutton aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure if this is credible, but, as an example, &lt;a href=&quot;http://laasdata.com/turbos/turbos-malaysia-icao-9m.php&quot; rel=&quot;noreferrer&quot;&gt;there are fewer than 30 non-air carrier turboprops&lt;/a&gt; (Caravans, twin Cessnas, twin Beeches, and a lone Cheyenne) registered in Malaysia, and 10 are registered to the air force. The same site says Jordan has 7, 6 of them in the air force. Where are the national air carrier pilots getting their twin time? SIC in domestic carrier ATRs and Dash-8s? &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="946" LastEditDate="2015-01-02T10:10:10.293" LastActivityDate="2015-01-08T21:01:58.383" Title="How do non-US pilots get the hours necessary for an ATP?" Tags="&lt;flight-training&gt;&lt;icao&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11471" PostTypeId="2" ParentId="11468" CreationDate="2015-01-02T09:28:44.780" Score="11" Body="&lt;p&gt;Under the rules of ICAO Annex 1, Personnel Licensing, you don't need an ATP License to fly as second in command (SIC) on a commercial aircraft required to be operated with a co-pilot. A commercial pilot license (CPL) is sufficient to be SIC on an aircraft that requires to be operated by more than a single pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And since 2006 ICAO have defined a Multi Crew Pilot License that also allows a pilot to be second in command on a commercial air transportation multi-crew aeroplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The  &lt;a href=&quot;http://www.icao.int/safety/airnavigation/pages/peltrgfaq.aspx#anchor24&quot; rel=&quot;nofollow&quot;&gt;ICAO website&lt;/a&gt; about Multi-Crew Pilot Licence (MPL):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The MPL allows a pilot to exercise the privileges of a co-pilot in a&#xA;  commercial air transportation on multi-crew aeroplanes. It provides&#xA;  the aviation community with an opportunity to train pilots directly&#xA;  for co-pilot duties. It is a new licence that has been introduced in&#xA;  addition to the existing pilot licences defined in Annex 1 — Personnel&#xA;  Licensing.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The licence focuses on ab initio airline pilot training.&#xA;  MPL training and assessment will be competency-based and involve a&#xA;  multi-crew environment and threat and error management from the onset.&#xA;  It provides for greater use of flight simulation training devices and&#xA;  include mandatory upset training. At this stage, only aeroplanes are&#xA;  considered for this new licence. The details of the requirements for&#xA;  the licence are contained in Annex 1 — Personnel Licensing and in the&#xA;  Procedures for Air Navigation Services — Training (PANS-TRG). These&#xA;  documents outline the minimum international Standard for the&#xA;  implementation of the MPL by any State; they can be purchased directly&#xA;  from ICAO through the Document Sales Unit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In Annex 1, the requirements are laid down for the MPL. One of the requirements says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Experience&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2.5.3.1&lt;/strong&gt; The applicant shall have completed in an approved training course not less than 240 hours as pilot flying and pilot&#xA;  not flying of actual and simulated flight. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The MPL, combined with a type rating, will get you to the right hand seat of the aircraft of choice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's likely there are 250-to-500-hours commercial pilots flying Second In Command (SIC) into JFK. With experience in Beech Bonanza's, Cheyenne/Seminole, maybe CitationJet, a lot of simulator time and a couple of hours in a B777.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your title question, in many countries pilots get their ATPL after building hours as SIC flying with a CPL or MPL within an airline training scheme. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-08T20:00:20.500" LastActivityDate="2015-01-08T20:00:20.500" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11472" PostTypeId="2" ParentId="11411" CreationDate="2015-01-02T09:47:43.503" Score="9" Body="&lt;p&gt;I work on these panels which get the data (both IFE and cockpit display panels for a big OEM and there are very few in the world :)). This is all Air data systems which are providing all the data. We get this data from various sensors placed inside the cockpit or on aircraft exterior including wings and tail. Their are different kind of data transmission buses like ARINC which transmit that data then the required data is fed to IFE system through a protocol but most crucial data like data coming from Weather Radar etc is kept for Pilot usage and is displayed on the cockpit display panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your question Altitude, elevation. azimuth there are some radars in the aircraft which gives that data and some of these radars measure and send this data using CAN protocol with very high speed varying from 40ms to 100ms.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-01-02T09:47:43.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11473" PostTypeId="1" AcceptedAnswerId="11475" CreationDate="2015-01-02T11:32:15.533" Score="3" ViewCount="2046" Body="&lt;p&gt;I am 16 and am very interested in becoming a private pilot, and fly flight simulators. I do not have enough money for the entire training. I can only afford 5 flying lessons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to learn majority of flight maneuvers using a flight simulator and just take a few lessons to get used to the feel of a real aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the list of topics that you need to learn when gaining your private pilot license?&lt;/p&gt;&#xA;" OwnerUserId="5631" LastEditorUserId="65" LastEditDate="2015-01-02T14:58:19.393" LastActivityDate="2015-01-02T14:58:19.393" Title="Can self-study and FSX substitute for the majority of PPL training?" Tags="&lt;flight-training&gt;&lt;ppl&gt;&lt;flight-simulator&gt;" AnswerCount="2" CommentCount="7" ClosedDate="2015-01-08T14:02:09.547" ContentLicense="CC BY-SA 3.0" />
  <row Id="11475" PostTypeId="2" ParentId="11473" CreationDate="2015-01-02T13:25:07.260" Score="7" Body="&lt;p&gt;There are usually a minimum required hours of flying you need to do, so the answer is no. Simon mentions in the comments that in the UK the minimum hours is 45.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If money is of issue, you should also consider other options such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Gliding&quot;&gt;gliding&lt;/a&gt; which is considerably cheaper. At least in Finland if you gather enough hours in a glider, you can then get other licenses with less hours required. Besides after getting enough hours you would be older and perhaps have a job that can pay for our hobby.&lt;/p&gt;&#xA;" OwnerUserId="5580" LastActivityDate="2015-01-02T13:25:07.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11476" PostTypeId="1" AcceptedAnswerId="11479" CreationDate="2015-01-02T14:12:07.847" Score="30" ViewCount="9126" Body="&lt;p&gt;In the event of a crash, facing backward sounds much safer:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Forces are applied on a  much larger surface (your whole back is in contact with the seats, instead of just a seatbelt and maybe the opposite seat)&lt;/li&gt;&#xA;&lt;li&gt;Most passenger are already in position in case of an unpredicted crash.&lt;/li&gt;&#xA;&lt;li&gt;Passenger without a seatbelt might have higher survival rate&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Flying objects would maybe be more dangerous, but&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What made designers do it this way ?&lt;/li&gt;&#xA;&lt;li&gt;Is there any plane with such a configuration ?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="13197" LastEditDate="2016-04-15T21:57:24.273" LastActivityDate="2019-08-07T18:05:27.353" Title="Why are passenger seats not facing backward on an airplane?" Tags="&lt;safety&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11477" PostTypeId="1" AcceptedAnswerId="11480" CreationDate="2015-01-02T14:48:11.173" Score="3" ViewCount="777" Body="&lt;p&gt;In reading about software and equipment design for aircraft I'm finding a lot of references to various standards like &quot;DO-178B, Software Considerations in Airborne Systems and Equipment Certification&quot;, but I'm having a hard time finding copies of these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a central repository or location where I can review or purchase these standards?&lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="64" LastEditDate="2015-01-03T22:43:19.633" LastActivityDate="2015-01-04T10:45:17.700" Title="Where can I find the standards for airborne systems software design? Is there a central repository for this information?" Tags="&lt;avionics&gt;&lt;software&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11478" PostTypeId="2" ParentId="11473" CreationDate="2015-01-02T14:57:49.627" Score="8" Body="&lt;p&gt;Unfortunately, no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you learn and practice and master the flying skills in a flight simulator, you will become a certified pilot only for that simulator, not for real life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You didn't mention the country, but you can look at &lt;a href=&quot;https://aviation.stackexchange.com/a/1380/65&quot;&gt;this answer&lt;/a&gt; to find all the requirements to become a private pilot in USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a flight simulator, you can learn many very valuable skills which will be very useful in your actual flying (and many many pilots do a lot of practice in a simulator), but in no way it can completely replace actual flying. There are many things you can only feel in actual flying experience. You can make any mistake in a simulator and no harm is done, but not in actual flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everything in flying is expensive. Even after you get your PPL, you still have to pay for flying afterwards. Since you are young enough not to have chosen a career path yet (probably), why don't you try to become an airline pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the answer to your second question, a few topics are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the airplane and its physics&lt;/li&gt;&#xA;&lt;li&gt;its engine&lt;/li&gt;&#xA;&lt;li&gt;weather&lt;/li&gt;&#xA;&lt;li&gt;effects of weather and altitude on pilots&lt;/li&gt;&#xA;&lt;li&gt;navigation&lt;/li&gt;&#xA;&lt;li&gt;planning&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;... and many other topics&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are tons of material available covering these topics. FAA has a wide array of &lt;a href=&quot;http://www.faa.gov/pilots/training/&quot; rel=&quot;nofollow noreferrer&quot;&gt;reading material&lt;/a&gt; which you can download for free.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-01-02T14:57:49.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11479" PostTypeId="2" ParentId="11476" CreationDate="2015-01-02T15:20:41.287" Score="24" Body="&lt;p&gt;You are absolutely correct, &lt;a href=&quot;http://articles.sun-sentinel.com/1991-07-07/news/9101240867_1_seat-belt-rear-facing-aviation-safety&quot; rel=&quot;noreferrer&quot;&gt;backward facing seats are safer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But tradition and a subjective feeling of being treated better means that people will prefer to be seated facing forward. Some even claim that they develop motion sickness when sitting backwards. This can indeed be the case for some people in trains with their big windows, but much less so in aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just note which seats will be occupied last in a train with lounge/mixed seating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to cram the highest number of passengers into their planes, the airlines would need to convert all seats to the backward orientation, and you can be sure there will be some passengers who will complain. If passenger safety would be important to them, airlines could already use better seatbelts, like the 5-point-harnesses used in gliders and aerobatics planes, but they all use the minimum lap belt which is mandated and nothing more. Convenience and cost always win over safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I need to mention two caveats:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;If passengers should be seated backwards, the industry needs to develop new seats. It will not be helpful to turn existing seats around - they would collapse at much lower loads than what a backward-sitting human can sustain. However, to fully support these higher loads, seats will be more heavy and possibly even the floor structure needs to be beefed up.&lt;/li&gt;&#xA;&lt;li&gt;Backward-facing seating will only help in the fraction of cases where deceleration loads are too high for a forward-facing person, but low enough to make the crash survivable. If the plane flies into a mountain or ditches and sinks before people get out, the better seating will not help.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Some military transports have backward-facing seats. In some crashes, the survivability rate was seven times higher in those than in forward-facing seats. Early air travel also used mixed seating, e.g. on the Zeppelins or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Do_X&quot; rel=&quot;noreferrer&quot;&gt;Dornier Do-X&lt;/a&gt;. One airline to use mixed seating was Southwest Airlines with their &lt;a href=&quot;http://www.flyertalk.com/forum/travelbuzz/289369-southwest-love-seats-will-you-miss-them.html&quot; rel=&quot;noreferrer&quot;&gt;&quot;love seats&quot;&lt;/a&gt;, and business jets have mixed seating as standard. Thanks to @reirab for pointing out that United Business class also has some backward-facing seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3f787.jpg&quot; alt=&quot;Cabin of the Do-X&quot;&gt;&#xA;Cabin of the Do-X. No seatbelts, seats not bolted to the floor. These were the days ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CL1Km.jpg&quot; alt=&quot;Cabin of the Dassault Falcon 7X business jet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin of the Dassault Falcon 7X business jet.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-08T03:57:11.847" LastActivityDate="2015-05-08T03:57:11.847" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11480" PostTypeId="2" ParentId="11477" CreationDate="2015-01-02T16:27:45.073" Score="7" Body="&lt;p&gt;Many of these are Radio Technical Commission for Aeronautics (RTCA) standards.&lt;br&gt;&#xA;You can get these documents from the &lt;a href=&quot;http://www.rtca.org/store_product.asp?prodid=581&quot; rel=&quot;nofollow&quot;&gt;RTCA website&lt;/a&gt;. They are provided free of charge to RTCA members, non-members have to pay. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively you can acquire the European equivalents from EUROCAE (RTCA DO-178B is &lt;a href=&quot;http://www.eurocae.net/eshop/catalog/advanced_search_result.php?keywords=ED-12B&quot; rel=&quot;nofollow&quot;&gt;ED-12B&lt;/a&gt; in the &lt;a href=&quot;https://www.eurocae.net/eshop/catalog/index.php&quot; rel=&quot;nofollow&quot;&gt;EUROCAE eShop&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to be up-to-date (for example if you're building a new avionics system), you should buy the latest version of the standard, such as &lt;a href=&quot;http://www.rtca.org/store_product.asp?prodid=803&quot; rel=&quot;nofollow&quot;&gt;DO-178&lt;strong&gt;C&lt;/strong&gt;&lt;/a&gt; / &lt;a href=&quot;http://www.eurocae.net/eshop/catalog/advanced_search_result.php?keywords=ED-12C&quot; rel=&quot;nofollow&quot;&gt;ED-12&lt;strong&gt;C&lt;/strong&gt;&lt;/a&gt;, which is the latest edition of your example above (published in 2012).&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="64" LastEditDate="2015-01-03T22:48:03.793" LastActivityDate="2015-01-03T22:48:03.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11481" PostTypeId="1" AcceptedAnswerId="11483" CreationDate="2015-01-02T16:56:28.473" Score="17" ViewCount="16339" Body="&lt;p&gt;According to &lt;a href=&quot;http://youtu.be/Hv-e8J8Sq48?t=2m16s&quot;&gt;this video on jet engine blades&lt;/a&gt;, titanium is never used for the turbine, because it &quot;melts and burns at the temperature of the flame&quot;. Only the blades of the compressor are made of this material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the melting temperature of titanium is higher than that of any steel alloys I could find, and titanium produces a protective layer of oxides on the surface. What other properties of titanium make using it impossible?&lt;/p&gt;&#xA;" OwnerUserId="5696" LastEditorUserId="64" LastEditDate="2015-01-09T22:47:15.833" LastActivityDate="2017-10-09T06:52:53.827" Title="Why are turbine blades not made out of titanium, only compressor blades?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;turbine&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11482" PostTypeId="2" ParentId="11468" CreationDate="2015-01-02T16:58:21.010" Score="3" Body="&lt;p&gt;Well it's much harder to get inside a cockpit without such opportunities. In Europe, we have some carriers (for example Lufthansa or SWISS) who offer ab initio programs. You can also make an ATPL at a flight school but chances to get a job afterwards are almost zero. Some carriers have job offers for &quot;Ready Entries&quot; with frozen ATPLs and without Type Rating but that's a minority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases to become a pilot you need to get one of the rare ab initio places. &#xA;All in all I thing it's harder to become a pilot in the EU than in the US.&lt;/p&gt;&#xA;" OwnerUserId="5697" LastEditorUserId="65" LastEditDate="2015-01-08T21:01:58.383" LastActivityDate="2015-01-08T21:01:58.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11483" PostTypeId="2" ParentId="11481" CreationDate="2015-01-02T20:29:27.243" Score="26" Body="&lt;p&gt;Titanium is unsuitable because it will react with oxygen and carbon at high temperature, well below its melting point, making it very hard and brittle. Welding titanium is very complicated because it needs to be shielded extremely well from any oxygen when hot. Ti$_3$O will form above 500°C, and Ti$_2$O above 600°C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initially turbine blades were made of steel alloys, but they have been displaced by &lt;a href=&quot;http://en.wikipedia.org/wiki/Inconel&quot; rel=&quot;noreferrer&quot;&gt;nickel alloys&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, they operate in an environment which requires constant &lt;a href=&quot;http://en.wikipedia.org/wiki/Turbine_blade#Methods_of_cooling&quot; rel=&quot;noreferrer&quot;&gt;cooling&lt;/a&gt;, so they can be 200 - 300°C cooler than the turbine entry temperature of the gas coming from the combustor(s). Modern turbine blades are hollow and have a perforation at their leading edge. Pressurized, relatively cool air is forced through the blades and the perforation and flows around the blade's surface, creating a cool sheet of air to shield the blade from the hot gas. Also, before entering the turbine the gas is accelerated, which already lowers its temperature. See the plot below of parameters inside an older engine taken from &lt;a href=&quot;http://www.cast-safety.org/pdf/3_engine_fundamentals.pdf&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eLcXa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly past the fuel injectors the maximum gas temperature of approx. 1800°C is reached, which drops to 1100°C at the entry to the first turbine stage. Note that this temperature has been raised to 1500°C in modern military engines! At the same time, the highest temperature is connected with the lowest speed (30 m/s), and the flow accelerates to 200 m/s directly before entering the first turbine stage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Titanium in contact with oxygen would lose a lot of its strength at these temperatures, even though its melting point is at 1650°C.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-02T21:04:59.313" LastActivityDate="2015-01-02T21:04:59.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11484" PostTypeId="2" ParentId="11443" CreationDate="2015-01-02T20:51:49.840" Score="39" Body="&lt;p&gt;I worked as a flight attendant for several years and I am still employed within the industry but in a different capacity, so I know a thing or two about this topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight Attendants (FAs) are strictly required to be seated during take-off and landings only and usually not during descent or climb, unlike passengers who are usually required to be seated and buckled. Then it depends on the local rules for how long they are supposed to stay there. In some airlines, the FAs must sit as long as the seatbelt sign is lit, while in others they can move about once the gears are up (you can hear this easily, as they make a loud sound when they are retracted). Other airlines might state FAs can move once the plane reaches a certain altitude and/or are given some sort of sign from the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is not one type of turbulence, but various classifications. Some of them are just light (small bounciness) and some are dangerous and can injure (or kill) people who are not seated and buckled. It is usually cabin crew who are the victims (I have personally been through this kind of turbulence). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, pilots will, during the &lt;a href=&quot;http://www.cabincrew.com/career-advice/what-happens-at-a-cabin-crew-pre-flight-briefing/1161&quot;&gt;pre-flight briefing&lt;/a&gt;, brief the cabin crew of any expected turbulence and will usually say something like: &quot;seatbelts are for everybody&quot; or &quot;seatbelts are for passengers&quot;. If things during the flight end up different from the forecast that was given to the pilots prior to the flight, the pilots will call the cabin crew and inform them. They will tell the cabin crew whether to continue the service because it is a light turbulence, they may suggest only to serve cold beverages, or tell the FAs to sit tight and secure everything if approaching severe turbulence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is basically the &quot;secret&quot; behind it. There is no magical training given to cabin crew on how to defeat the laws of physics and stand balanced while in turbulence; it is just the word from the pilots as they are the most knowledgeable about the weather conditions. The crew are only trained on types of turbulence and on how to secure the cabin and service carts quickly in case of sudden severe turbulence that was not detected in advance. In that case, they are told to hang on to anything and secure themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers, on the other hand, are required to be seated and buckled during all phases of the flight except cruise and when there is no turbulence. This is simply due to liability and not to add more complication in these critical times.&lt;/p&gt;&#xA;" OwnerUserId="5699" LastEditorUserId="5699" LastEditDate="2015-01-03T16:17:42.027" LastActivityDate="2015-01-03T16:17:42.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11485" PostTypeId="2" ParentId="3529" CreationDate="2015-01-03T02:34:56.893" Score="3" Body="&lt;p&gt;In the event of a disagreement between the transponder altitude and the pilot's stated altitude ATC is required to go with what you tell them on the radio. So if their screen says you are at 18,000 but you say &quot;no, I'm at 15,000&quot; they go with that number. Therefore, if you do fudge your numbers a bit for whatever reason, ATC will be unable to do anything about it. They will also not issue avoidance vectors to the A340 approaching head-on at 0.8mach - you are, after all, 3000 feet lower than the Airbus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the &quot;dreaded phone number to call&quot; - once you have landed and parked you are no longer air traffic and no longer required to follow their instructions. In many cases the FAA cannot issue you a violation without your co-operation, so don't give them any.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-01-03T02:34:56.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11486" PostTypeId="1" CreationDate="2015-01-03T16:47:40.227" Score="-2" ViewCount="1559" Body="&lt;p&gt;I occasionally see such a thing on final approach to Northolt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its very noisy and looks vaguely military.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anybody know what it is and what its purpose is (other than to annoy me)?&lt;/p&gt;&#xA;" OwnerUserId="5710" LastEditorUserId="62" LastEditDate="2015-01-03T17:03:46.217" LastActivityDate="2015-01-03T21:50:10.590" Title="Twin engine pusher plane seen at Northolt" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-01-03T23:47:24.960" ContentLicense="CC BY-SA 3.0" />
  <row Id="11488" PostTypeId="2" ParentId="11486" CreationDate="2015-01-03T18:06:57.500" Score="1" Body="&lt;p&gt;Sounds like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piaggio Avanti&lt;/a&gt; - it's the only common twin pusher, and it's known for its &quot;buzzsaw&quot; sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Hl0P.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-01-03T18:06:57.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11489" PostTypeId="1" AcceptedAnswerId="11492" CreationDate="2015-01-03T19:48:21.790" Score="18" ViewCount="5252" Body="&lt;p&gt;From what I have read it is illegal for the &lt;a href=&quot;http://en.wikipedia.org/wiki/National_Transportation_Safety_Board&quot;&gt;National Transportation Safety Board&lt;/a&gt; to release Cockpit Voice Recordings, while they are allowed to release its transcripts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.airdisaster.com/cvr/&quot;&gt;AirDisaster&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is illegal for the National Transportation Safety Board, who regulates these recordings, to release them to the public. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.ntsb.gov/news/Pages/cvr_fdr.aspx&quot;&gt;NTSB&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The transcript, containing all pertinent portions of the recording, can be released to the public at the time of the Safety Board's public hearing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why? What's the issue with releasing Cockpit Voice Recordings?&lt;/p&gt;&#xA;" OwnerUserId="1400" LastEditorUserId="64" LastEditDate="2015-01-05T17:11:34.820" LastActivityDate="2015-03-27T04:57:49.670" Title="Why does the NTSB release transcripts of Cockpit Voice Recordings, but not the actual recordings?" Tags="&lt;accident-investigation&gt;&lt;ntsb&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11490" PostTypeId="1" AcceptedAnswerId="11494" CreationDate="2015-01-03T20:20:14.807" Score="3" ViewCount="590" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;When you file a flight plan from Oakland to Honolulu&lt;br&gt;&#xA;  you put &quot;Glory&quot; as your alternate destination.&lt;sup&gt;[1]&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is that the correct way to file the flightplan? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scanning back a few paragraphs, the airplane in question was a Cessna 402.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[1]&lt;/sup&gt; B. May, &lt;em&gt;Under His Wing: Adventures in Trusting God&lt;/em&gt;, p.&amp;nbsp;40 (Multnomah Publications, 1991. ISBN 0-930014-94-4.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note while the publication is 1991, the actual copyright is 1979, so we are looking before that date.&lt;/p&gt;&#xA;" OwnerUserId="5711" LastEditorUserId="12720" LastEditDate="2016-02-10T20:01:10.077" LastActivityDate="2016-02-10T20:01:10.077" Title="No alternate destination when flying from Oakland to Honolulu: is that correct?" Tags="&lt;flight-planning&gt;&lt;aviation-history&gt;&lt;flight-plans&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11491" PostTypeId="2" ParentId="8781" CreationDate="2015-01-03T20:23:38.013" Score="2" Body="&lt;p&gt;Read 91.157: (d) &quot;The determination of visibility by a pilot in accordance with paragraph (c)(2) of this section is not an official weather report or an official ground visibility report.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though this is in 157 not 155, I think that if you were involved in a weather-related incident, the FAA would argue that the OFFICIAL reported weather controls, not the pilots judgment. This is probably what the Instructor means. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, many uncontrolled fields, such as yours, have non-official automated reporting, which you could argue is advisory and not regulatory. This is probably what the Examiner means.  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-03T20:23:38.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11492" PostTypeId="2" ParentId="11489" CreationDate="2015-01-03T20:58:37.890" Score="15" Body="&lt;p&gt;From NTSB site, &lt;a href=&quot;http://www.ntsb.gov/about/foia/Pages/foia_exemptions.aspx&quot; rel=&quot;nofollow&quot;&gt;regarding FOIA requests&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Cockpit Voice Recorder (CVR) tapes. Title 49 U.S.C. § 1114(c)&#xA;  prohibits the release of any CVR tape. However, the NTSB may release a&#xA;  CVR transcript (edited or unedited), in accordance with 49 U.S.C. §&#xA;  1114(c)(1).&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Transcripts may be disclosed, but not 'tapes'. Which makes sense, as transcripts may be edited to remove parts that are not meaningful for the investigation, but can be  unnecessary intrusions into private life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, when the NTSB is participating to foreign investigations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Records or information relating to the NTSB's participation in foreign&#xA;  aircraft accident investigations. 49 U.S.C. § 1114(f) prohibits the&#xA;  release of this information before the country conducting the&#xA;  investigation releases its report or 2 years following the accident,&#xA;  whichever occurs first&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.law.cornell.edu/uscode/text/49/1114&quot; rel=&quot;nofollow&quot;&gt;49 U.S. Code § 1114 - Disclosure, availability, and use of information&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="64" LastEditDate="2015-03-27T04:57:49.670" LastActivityDate="2015-03-27T04:57:49.670" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11494" PostTypeId="2" ParentId="11490" CreationDate="2015-01-03T22:06:23.857" Score="7" Body="&lt;p&gt;&lt;strong&gt;There are plenty of alternative airports in Hawaii, but none in-between of course. So what the author is getting at is that you're probably going to be dead if you run into trouble.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I can't say I know anything much about the Cessna 402, it apparently has a normal range of around 1,273 nm (1,467 mi, 2,360 km), compared to a distance Hawaii-Oakland of 2050nm (2359mi, 3797km). Hence, you're going to have to install additional fuel tanks and fly pretty heavy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There a few considerations if you get a problem: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You will have to descend since the engine can't generate enough thrust at that cruise altitude. I found a source stating the ceiling for both engines is around 26180 ft compared to 11320 ft for one engine. &lt;/li&gt;&#xA;&lt;li&gt;The fuel consumption increases in the remaining engine and will be greater than the total for both engines for the same flying conditions.&lt;/li&gt;&#xA;&lt;li&gt;You're going to have to run the remaining engine hard for the remain of the flight.&lt;/li&gt;&#xA;&lt;li&gt;If your temporary ferry tanks screw up (or any of the normal ones for that matter as well), you won't make it.&lt;/li&gt;&#xA;&lt;li&gt;You may damage/break the gear if you have to return to the airport overloaded. &quot;I once saw a Cessna 402 parked on the ramp at Honolulu with the gear punched half way up into the wings from a poorly executed overweight landing.&quot; &lt;a href=&quot;http://www.planeandpilotmag.com/proficiency/pilot-skills/get-the-balance-right.html&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can't do a calculation on for what portion of the flight you would be 'screwed' but I imagine it might very well be a bit of the journey. &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-46887.html&quot; rel=&quot;nofollow&quot;&gt;Several people&lt;/a&gt; seem to be in the opinion it's a pain to fly heavy and difficult to with one engine. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-01-08T16:36:36.723" LastActivityDate="2015-01-08T16:36:36.723" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11496" PostTypeId="1" CreationDate="2015-01-04T11:37:30.883" Score="3" ViewCount="1048" Body="&lt;p&gt;With the revelation that flight QZ8501 did not have permission to fly the route on the day it crashed, I'm wondering how common an occurrence this is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it something that all airlines do every now and then and is actually not a serious thing? Just seems it would hardly be an oversight - as you'd think since they have to advertise tickets, they would've planned to take that route on that day months in advance. It should be a fairly straight forward thing to check whether they were authorised to fly then.&lt;/p&gt;&#xA;" OwnerUserId="5714" LastEditorUserId="946" LastEditDate="2015-01-04T12:07:28.400" LastActivityDate="2015-01-04T12:07:28.400" Title="How common is it for airlines to fly unauthorised flight paths?" Tags="&lt;airline-operations&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2015-01-04T23:16:11.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="11497" PostTypeId="2" ParentId="11438" CreationDate="2015-01-04T12:13:33.480" Score="2" Body="&lt;p&gt;You will see them very soon. Actually, I have already made the software for that :) and we will be delivering to few of the Airlines very soon as I work on those systems where we will have the DVR (Digital Video Recorder) and and a live streaming panel. This recording is only manually controlled just by push of a button by pilot or crew. You will see them in B787s. There are few in A350 also for few airlines.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-01-04T12:13:33.480" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11498" PostTypeId="1" AcceptedAnswerId="11499" CreationDate="2015-01-04T15:14:45.310" Score="6" ViewCount="430" Body="&lt;p&gt;If someone can't afford to pay for flight training directly, is it possible to get commercial flight training with financial aid as part of a college degree?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the UK answer, see: &lt;a href=&quot;https://aviation.stackexchange.com/q/11366/65&quot;&gt;Do any UK universities include PPL/Commercial flight training as part of an aviation degree?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-01-05T15:16:05.313" Title="How can someone get FAA commercial flight training as part of an aviation degree?" Tags="&lt;flight-training&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11499" PostTypeId="2" ParentId="11498" CreationDate="2015-01-04T15:14:45.310" Score="5" Body="&lt;p&gt;In the US, there are 2 ways to become a certificated civilian pilot: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=898af63a181cfab86749b6fb139dcef0&amp;amp;node=pt14.2.61&amp;amp;rgn=div5&quot;&gt;Part 61&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr141_main_02.tpl&quot;&gt;Part 141&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 61 is done in informal classes and flights at a local flight school. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 141 is a professional pilot training program, with uniforms, classrooms, a full-time staff, and a uniform fleet of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are numerous US universities that offer bachelors' degrees using a part 141 program. You can find &lt;a href=&quot;http://www.globalair.com/directories/Colleges-Universities-38.html&quot;&gt;a list of such programs here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, many of these schools, such as &lt;a href=&quot;http://daytonabeach.erau.edu/admissions/estimated-costs/index.html&quot;&gt;Embry-Riddle&lt;/a&gt;, take the &lt;a href=&quot;https://fafsa.ed.gov/&quot;&gt;FAFSA&lt;/a&gt;, which is the  process for obtaining financial aid as for any other program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After graduating from one of these programs, you will have obtained all the training necessary to work as a flight instructor, or as a commercial pilot under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=898af63a181cfab86749b6fb139dcef0&amp;amp;node=pt14.3.119&amp;amp;rgn=div5&quot;&gt;Part 119&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Private Pilot Single Engine&lt;/li&gt;&#xA;&lt;li&gt;Instrument Pilot Single and Multi-Engine&lt;/li&gt;&#xA;&lt;li&gt;Commercial Pilot Single and Multi-Engine&lt;/li&gt;&#xA;&lt;li&gt;Flight Instructor Single Engine&lt;/li&gt;&#xA;&lt;li&gt;Flight Instructor Instrument&lt;/li&gt;&#xA;&lt;li&gt;Multi-Engine Flight Instructor&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You will have also earned either an Associates or Bachelors degree, usually in something like Aviation Engineering or Aviation Operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will not, however, have flown enough hours to get a job flying air taxi or cargo under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=898af63a181cfab86749b6fb139dcef0&amp;amp;node=pt14.3.135&amp;amp;rgn=div5&quot;&gt;Part 135&lt;/a&gt;, which requires 500 hours to be the pilot-in-command.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-04T15:14:45.310" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11500" PostTypeId="2" ParentId="1456" CreationDate="2015-01-04T15:39:56.287" Score="3" Body="&lt;p&gt;There are three types of ATC service: terminal, approach control, and center (ARTCC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you said you're en route, you'll want either approach control or center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're inside the Mode C veil (but obviously not already in the airspace) of a Class B or Class C, or if you're near a military base (which all have radar, 'natch), you'll watch to contact approach control, whose frequencies can be found on the tabs of the sectional, such as this example from San Francisco:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bqLrl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're not within the Mode C veil, call up &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_watch&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flightwatch&lt;/a&gt; 122.0. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flightwatch is manned at all times, but it usually takes them at least 5-10 seconds to respond because its infrequently used and they're busy with other things.  The trick is not to make your request on the first call up, but do announce your position, since Flight Service has many transmitters, and they will pick the one that is closest to you:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N347T: Flightwatch, Mooney 3-4-7-Tango, Crazy Woman&lt;br&gt;&#xA;  10 seconds pass...&lt;br&gt;&#xA;  Fligihtwatch: Mooney near Crazy Woman, Flightwatch, go ahead (they probably won't get your numbers, but they will pick out your type and position)&lt;br&gt;&#xA;  N347T: Flightwatch, Mooney 3-4-7-Tango, what's the frequency for flight following near C-Z-I?&lt;br&gt;&#xA;  Flightwatch: 4-7-Tango, for radar services near C-Z-I, contact Salt Lake Center on ....  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many GPS units have a &quot;nearest&quot; function that will provide frequencies for the nearest FSS or Center:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sJBVH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-04T16:06:33.037" LastActivityDate="2015-01-04T16:06:33.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11501" PostTypeId="2" ParentId="11442" CreationDate="2015-01-04T17:08:52.907" Score="5" Body="&lt;p&gt;As David Richerby correctly said, ice degrades performance. The more ice, the more the performance is degraded until the point where the aircraft is not able to climb out. So if there was just some ice, they could have taken off and then noticed degraded performance and returned. In this respect the comments are wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the comments are somewhat right in that the degraded performance would manifest from take-off, so it would likely be detected much sooner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the AvHerald article says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;…the crew stopped the climb due to an anti-ice problem and initiated a descent…&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which points to failure of (some of the) anti-ice systems that prevent accretion of ice on critical parts of the aircraft (pitot tubes, engine inlets, wing and elevator leading edges) during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DailyMail reporter clearly didn't know much about the issue (which can be forgiven; the reporter can't understand all the things in detail) and didn't bother to check (which they should have, but most news reporters won't let facts stand in a way of good story and Daily Mail ones even less so).&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-04T17:08:52.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11502" PostTypeId="2" ParentId="2036" CreationDate="2015-01-04T17:28:37.270" Score="7" Body="&lt;p&gt;&lt;em&gt;Forward flight&lt;/em&gt; in a helicopter means that the the horizontal component of lift is forward of vertical, and no turning component is present. Contrast to &lt;em&gt;turning flight&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Straight flight&lt;/em&gt; is forward flight, with the yaw string centered. Contrast to a &lt;em&gt;slip&lt;/em&gt; or a &lt;em&gt;skid&lt;/em&gt;, or &lt;em&gt;sidways&lt;/em&gt; or &lt;em&gt;backwards&lt;/em&gt; flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Level flight&lt;/em&gt; means that the helicopter maintains altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Cruise flight&lt;/em&gt; in a helicopter is the flight regime between departure and approach, at a power setting optimized for traveling between locations.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-08T20:33:10.153" LastActivityDate="2015-01-08T20:33:10.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11503" PostTypeId="2" ParentId="3406" CreationDate="2015-01-04T22:18:59.587" Score="1" Body="&lt;p&gt;EASA has published a memorandum with guidance on how to comply with the certification requirements. It is based on EUROCAE ED-12B/RTCA DO-178B, but is more specific.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is called &lt;em&gt;EASA CM - SWCEH – 002&lt;/em&gt; and you can find it &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/certification-docs-certification-memorandum-EASA-CM-SWCEH-002-Issue-01-Rev-01-Software-Aspects-of-Certification.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2176" LastActivityDate="2015-01-04T22:18:59.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11506" PostTypeId="1" AcceptedAnswerId="11507" CreationDate="2015-01-05T23:30:59.167" Score="55" ViewCount="17387" Body="&lt;p&gt;These days, on larger/newer aircraft at least, GPS navigation is ubiquitous.  So &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR&lt;/a&gt;s and &lt;a href=&quot;http://en.wikipedia.org/wiki/Non-directional_beacon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Non-directional Beacons&lt;/a&gt; (NDBs) are used less.  Wasn't the reason for airways because they were the connection points between VORs and NDBs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like a pilot could easily &quot;fly direct&quot; from one airport to another without using any intermediary checkpoints.  And yet I've been told on several occasions that most pilots use airways.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do pilots still use airways instead of flying direct?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="31425" LastEditDate="2020-03-22T19:45:52.867" LastActivityDate="2020-03-22T19:45:52.867" Title="Why do pilots use airways instead of just &quot;flying direct&quot; every time?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="11507" PostTypeId="2" ParentId="11506" CreationDate="2015-01-05T23:41:47.010" Score="64" Body="&lt;p&gt;Airways simply allow for better management of traffic.&lt;br&gt;&#xA;Imagine for a moment that everyone had an off-road capable car, if all the drivers were going &quot;GPS Direct&quot; to their destination how would drivers ensure separation? How would you avoid hitting other cars if there were no roads?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airways are the aviation solution to this problem: Defined routes between navaids (VORs, NDBs, and the like). Airways can also be defined using &quot;fixes&quot; defined by GPS coordinates which can provide something closer to &quot;GPS Direct&quot; routing while still providing a defined route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airways also provide a bunch of other benefits, including:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Traffic Flow Management&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flightplans in Europe are validated by the &lt;em&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Central_Flow_Management_Unit_%28CFMU%29&quot; rel=&quot;noreferrer&quot;&gt;CFMU (Central Flow Management Unit)&lt;/a&gt;&lt;/em&gt; and checked for criteria such as direction of airways (which can change during the day, e.g. one airway being for eastbound traffic only between 1000 UTC and 1400 UTC), correct flight level ranges and airways correctly connecting waypoints, such as fixes, VORs or NDBs. The bottleneck in all flight operations is understanding airport capacity (how many operations/hour) and sector capacity (how many aircraft handled per sector/per controller). The goal is sometimes to distribute traffic between two sectors, although having the same destination. Below you will find two routings to Düsseldorf - EDDL, one departing from &lt;a href=&quot;http://skyvector.com/?ll=51.41976382570769,7.536254885350317&amp;amp;chart=304&amp;amp;zoom=3&amp;amp;plan=A.ED.EDDP:F.ED.ORTAG:F.ED.KUMER:F.ED.GOTGI:V.ED.WRB:F.ED.TINSA:F.ED.ADEMI:F.ED.INBAX:F.ED.DOMUX:A.ED.EDDL&quot; rel=&quot;noreferrer&quot;&gt;Leipzig - EDDP&lt;/a&gt; and one from &lt;a href=&quot;http://skyvector.com/?ll=51.68958500713333,7.13452148690714&amp;amp;chart=304&amp;amp;zoom=3&amp;amp;plan=A.ED.EDDT:F.ED.BRANE:F.ED.GUGSU:V.ED.HLZ:F.ED.PERIK:F.ED.PIROT:F.ED.DENOL:V.ED.HMM:F.ED.XAMOD:A.ED.EDDL&quot; rel=&quot;noreferrer&quot;&gt;Berlin-Tegel - EDDT&lt;/a&gt; (click on links to see visual representation):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;EDDP - EDDL&#xA;ORTAG Q230 WRB T854 DOMUX&#xA;&#xA;EDDT - EDDL&#xA;BRANE Y200 HLZ T851 XAMOD&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The routing from EDDP to EDDL is going via WRB - TINSA - ADEMI - INBAX - DOMUX, which is within the boundaries of a sector called &lt;a href=&quot;http://www.vacc-sag.org/download/sectorfile.php?id=229&amp;amp;check=b9002078cf5fb0272bed17f1fc4ff324&quot; rel=&quot;noreferrer&quot;&gt;&quot;Paderborn High&quot; or PADH&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The routing from EDDT to EDDL is going via PIROL - DENOT - HMM - XAMOD, which is within the boundaries of a sector called &lt;a href=&quot;http://www.vacc-sag.org/download/sectorfile.php?id=229&amp;amp;check=b9002078cf5fb0272bed17f1fc4ff324&quot; rel=&quot;noreferrer&quot;&gt;&quot;Hamm High/Medium&quot; or HMMH/HMMM&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During peak hours, both sectors are separate and deal with traffic only within their sector, which uses the full capacity of each controller handling the sector. Outside peak hours, the sectors can be combined and worked by one controller. This allows a granular usage of controller resources and airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Separation between Traffic&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the example above we have seen that there is 2 routing endpoints at Düsseldorf - EDDL for traffic arriving from the North-East and South-East, XAMOD and DOMUX. Both waypoints or fixes are respective STAR or transition entry-points for arrivals into Düsseldorf. By using a standardized routing to and from airports, we can now expect traffic to always arrive via these two points from the east, unless other coordination has been achieved by the ATC units involved. Looking at the reverse routing for both airports, we will see these routes:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;EDDL - EDDP&#xA;NUDGO Z858 BERDI Z21 BIRKA T233 LUKOP&#xA;&#xA;EDDL - EDDT&#xA;MEVEL L179 OSN L980 DLE T207 BATEL&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;MEVEL and NUDGO are two of the SID exit waypoints out of Düsseldorf, &lt;a href=&quot;http://skyvector.com/?ll=51.68969852167173,7.134521477726325&amp;amp;chart=302&amp;amp;zoom=3&amp;amp;plan=F.ED.XAMOD:F.ED.MEVEL&quot; rel=&quot;noreferrer&quot;&gt;MEVEL being 10nm north of XAMOD&lt;/a&gt; and NUDGO being 26nm east of DOMUX, however the relevant fix here is ELBAL, which is one of the fixes on the SID23L from Düsseldorf to NUDGO, &lt;a href=&quot;http://skyvector.com/?ll=51.419649642834294,7.5362548761497585&amp;amp;chart=302&amp;amp;zoom=3&amp;amp;plan=F.ED.DOMUX:F.ED.ELBAL&quot; rel=&quot;noreferrer&quot;&gt;which is 16nm south of NUDGO&lt;/a&gt;. With something simple as using standardized entry and exit fixes to and from an airport, we have managed to maintain a traffic flow with ensured separation between departing and arriving traffic, something which would not be possible with GPS direct routing or would require constant ATC vectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Handoffs from ATC Unit to ATC Unit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above examples show different routings and sometimes different sectors handling traffic on these routes. How is traffic handed off to other controllers and where? A handoff consists of moving the radar track of the aircraft from one controller to another and thereafter instructing the aircraft to change the frequency to the next sector controller. Handoffs are initiated at sector boundaries, at specific fixes, which have been agreed on between different ACC (Area Control Centers) or sometimes even within one ACC between single sectors. Since we are already familiar with Düsseldorf airspace, let's use the below routing from &lt;a href=&quot;http://skyvector.com/?ll=51.01663451649939,8.306396477685288&amp;amp;chart=302&amp;amp;zoom=3&amp;amp;plan=A.ED.EDDM:F.ED.GIVMI:F.ED.ERNAS:F.ED.TALAL:F.ED.ERMEL:F.ED.INBED:F.ED.AMOSA:F.ED.IBAGA:F.ED.EDUDU:F.ED.OSBIT:F.ED.TEKTU:F.ED.SOGMI:F.ED.ARPEG:F.ED.BADGO:F.ED.ABILU:F.ED.ADEMI:F.ED.INBAX:F.ED.DOMUX:A.ED.EDDL&quot; rel=&quot;noreferrer&quot;&gt;München to Düsseldorf&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;EDDM - EDDL&#xA;GIVMI Y101 TEKTU Z850 ADEMI T854 DOMUX&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;From the graphical represenation you will see that traffic from EDDM to EDDL will pass the waypoint ARPEG, which is close to the destination airport. Before reaching the waypoint ARPEG, aircraft will be under control of either the &lt;a href=&quot;http://www.vacc-sag.org/download/sectorfile.php?id=229&amp;amp;check=b9002078cf5fb0272bed17f1fc4ff324&quot; rel=&quot;noreferrer&quot;&gt;Hersfeld (HEF) or Gedern (GED) sector&lt;/a&gt; (page 5) and need to descend towards the destination airport. The next sector for arriving traffic into Düsseldorf via ARPEG would be Paderborn High Sector (PADH). The agreements between HEF/GED and PADH are that arriving traffic to Düsseldorf via ARPEG is to be expected at FL240 level at ARPEG and released after handoff for further descent through PADH, even if the aircraft has not yet crossed the sector boundary and is not in PADH airspace. These coordination waypoints and handoff procedures are documented in Letters of Agreement between or within an ACC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weather&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When weather (wrong-way lows, strong jetstreams, storms, etc) affects the Direct route, flight dispatchers will pro-actively suggest routes around it. It's not unusual for NYC-SFO traffic to be routed over Canada or over Kentucky when the Midwest is storming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Exceptions - Free Route Airspace&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where airport and air traffic density allows, the use of airways is not mandatory or in some cases, not even expected or provisioned for. One example is the &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/article/files/2011march-free-route-airspace-maastricht.pdf&quot; rel=&quot;noreferrer&quot;&gt;Free Route Airspace overhead Scandinavia&lt;/a&gt;, where a portion of airspace can be freely used between defined entry and exit points. Similar systems are also being discussed by &lt;a href=&quot;http://www.nats.aero/environment/consultations/pc-route-free-airspace/&quot; rel=&quot;noreferrer&quot;&gt;NATS UK&lt;/a&gt; and the  &lt;a href=&quot;http://en.wikipedia.org/wiki/Next_Generation_Air_Transportation_System&quot; rel=&quot;noreferrer&quot;&gt;FAA NextGen Air Transportation System&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For more information on airways and their use, see also the related question:&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11514/is-there-a-difference-between-how-commercial-jets-and-ga-aircraft-use-airways&quot;&gt;Is there a difference between how commercial jets and GA aircraft use airways?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some material courtesy of VATSIM or VATSIM Germany. While only for simulation use, the material used is as accurate and close to the real sectorisation or procedures as possible, so should be sufficient to explain the concepts presented here.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-01-07T12:50:06.260" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11508" PostTypeId="2" ParentId="11506" CreationDate="2015-01-05T23:44:46.007" Score="11" Body="&lt;p&gt;Airways are safer, because you know where other pilots will be flying in order to avoid them. The rule of using an odd flight level for flying east, and an even flight level for flying west will also help to keep traffic separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safe cruising altitudes are also set based on the airways. There is an altitude per waypoint so a normal climb will let you get over the next hill, and per section between waypoints so you know how high that hill actually is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the airways system maintaining proper ground clearance would be much more work intensive. With the fixes all the pilot needs to do is keep a list with fixes and MEA/MCA (safe crossing altitudes) and follow the needle and cross them off as he reaches them and climb if necessary.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="1696" LastEditDate="2015-01-07T15:43:23.450" LastActivityDate="2015-01-07T15:43:23.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11510" PostTypeId="2" ParentId="11438" CreationDate="2015-01-06T09:28:04.647" Score="12" Body="&lt;p&gt;Many airlines do in fact have inflight camera feeds for Cabin surveillance so I do not think the question is relevant to most major airlines anymore.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a specific example, Emirates Airline employs the Cabin Video Monitoring Systems (CVMS) across its fleet of Airbus A380 aircraft. These Cabin cameras can be accessed by Cockpit crew through the System Display or the Cabin crew through the FAP (Flight Attendant Panel) and for any abnormal situation such as a hijacking/hostage situation on ground, the CVMS can be accessed on a laptop via the GSP (Ground Service Panel). Additionally, as mentioned above, they have landscape cameras installed for an external video feed but that is more of a feature for passengers.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantages of a CVMS in a hijacking/hostage situation such as positioning, identity, body language and weapons of the hijackers plus general operational advantages such as issues during boarding/offloading and other emergency situations such as an evacuation are great and not to be discounted.&lt;/p&gt;&#xA;" OwnerUserId="4435" LastEditorUserId="65" LastEditDate="2015-01-06T19:20:22.527" LastActivityDate="2015-01-06T19:20:22.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11511" PostTypeId="1" AcceptedAnswerId="11512" CreationDate="2015-01-06T10:12:40.143" Score="19" ViewCount="18716" Body="&lt;p&gt;A typical METAR or TAF reads something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;VRB04KT P6SM SCT025 BKN040 OVC060&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;P6SM&lt;/code&gt; means &quot;greater than 6 statute miles visibility.&quot;  Why in particular is it 6 miles--why not &lt;code&gt;P7SM&lt;/code&gt; or &lt;code&gt;P10SM&lt;/code&gt;?  Particularly since sometimes METARs and TAFs list actual visibilities greater than 6 statute miles anyway:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;28006KT 10SM CLR&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is 6 miles a limitation of commonly used equipment for measuring visibility, or something else?  &lt;/p&gt;&#xA;" OwnerUserId="2710" LastActivityDate="2020-09-26T03:28:45.397" Title="Why the number 6 in P6SM in a METAR/TAF?" Tags="&lt;flight-planning&gt;&lt;metar&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11512" PostTypeId="2" ParentId="11511" CreationDate="2015-01-06T12:47:03.853" Score="22" Body="&lt;p&gt;The METAR format is defined by the World Meteorological Organization's (WMO)  on behalf of ICAO. According to the &lt;a href=&quot;http://www.wmo.int/pages/prog/www/WMOCodes/Manual/Volume-I-selection/Sel2.pdf&quot;&gt;specification&lt;/a&gt; (section 15.6.3), visibility is to be reported in meters. The upper bound for visibility reporting is 9999, which indicates the visibility exceeds 10 kilometers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In North America, the METARs deviate from the standard format by using non-standard units. Visibility is reported in statue miles. Six statue miles is equivalent to 10 kilometers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence &gt; 6 statue miles is equal to the standard &gt; 10 kilometers.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-06T17:02:04.717" LastActivityDate="2015-01-06T17:02:04.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11513" PostTypeId="2" ParentId="11506" CreationDate="2015-01-06T14:23:12.383" Score="17" Body="&lt;p&gt;A simplistic explanation is,&#xA;pilots in controlled airspace fly along airways because that's where&#xA;the air traffic controllers want them to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of airways has to do with the way air traffic controllers keep track of all the&#xA;flights in the sector of airspace they control&#xA;(they need a way to organize the traffic so that they have a good mental&#xA;image of it and can guarantee that aircraft do not pass too close to each other),&#xA;as well as the fact that it is easier to communicate a path that&#xA;goes between published waypoints with three- or five-letter names than&#xA;a path that goes between points described by their numeric latitudes and longitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.hf.faa.gov/hfportalnew/Search/DOCs/Free%20Flight%20Research%20Issues%20and%20Literature%20Search.pdf&quot;&gt;free flight concept&lt;/a&gt;&#xA;proposes to allow these same aircraft to fly routes that do not&#xA;generally follow airways, but it requires big changes in the way&#xA;air traffic management is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This answer is based primarily on recollection of the&#xA;work I've done on the development and analysis of air traffic management&#xA;systems, mostly related to free flight, since 2001.)&lt;/p&gt;&#xA;" OwnerUserId="3831" LastEditorUserId="3831" LastEditDate="2015-01-06T14:38:17.327" LastActivityDate="2015-01-06T14:38:17.327" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11514" PostTypeId="1" AcceptedAnswerId="11516" CreationDate="2015-01-06T15:24:41.553" Score="14" ViewCount="1565" Body="&lt;p&gt;In the answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11506/why-do-pilots-use-airways-instead-of-just-flying-direct-every-time&quot;&gt;this question&lt;/a&gt; about why people use airways, one of the commentors pointed out that GA aircraft often use airways in a different fashion than commercial aircraft.  I couldn't tell from context why this is true though.  Is it laziness, spite, lack of knowledge?  Or is it simply that GA aircraft are instructed to use them differently?  Or, even, is it that GA aircraft are typically at a lower altitude so they simply have different airways?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do GA aircraft use airways different than large commercial planes?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2020-04-05T16:13:20.650" Title="Is there a difference between how commercial jets and GA aircraft use airways?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11515" PostTypeId="2" ParentId="11514" CreationDate="2015-01-06T15:42:35.443" Score="7" Body="&lt;p&gt;It depends on the type of aircraft, and the operational support behind the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Western US (as I would expect is also true for &lt;em&gt;Les Alpes&lt;/em&gt;), the terrain is quite high, and there is sparse radio coverage at lower obstacle-clearing altitudes. Lighter aircraft will opt for Federal Airways, which have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Minimum_en_route_altitude&quot; rel=&quot;noreferrer&quot;&gt;Minimum Enroute Altitude&lt;/a&gt; that ensures obstacle clearance, and radio navigation aid and voice communications coverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carriers have huge flight operations departments, which plan the routes taken by their aircraft.  Since carriers have scores of flights in the air, they are constantly adjusting routes for traffic and weather, and may file routes that a smaller operator wouldn't consider&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For smaller operations, there are &quot;Preferred IFR Routes&quot; published in the A/FD (see below).  They can also obtain &lt;a href=&quot;http://ww1.jeppesen.com/aviation/business/planning-solutions.jsp&quot; rel=&quot;noreferrer&quot;&gt;one-off or subscription flight operations from companies like Jeppesen&lt;/a&gt;, which give them the resources of a large flight operations department.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MOiKr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-06T15:50:43.273" LastActivityDate="2015-01-06T15:50:43.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11516" PostTypeId="2" ParentId="11514" CreationDate="2015-01-06T15:51:05.370" Score="10" Body="&lt;p&gt;In Europe, some airways are only available in certain flight level ranges, so a commercial airliner and a GA turbo-prop travelling from the same departure airport to the same destination airport could be travelling on different routes due to airway restrictions in place and the inability of one aircraft to climb to the same level as the other. Below the routing for PC12 operating IFR at FL150 and an A320 operating at FL250.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;(FPL-DEXAM-IG&#xA;-PC12/M-SDE1FGHIJ1RWXY/LB1&#xA;-EDDL1000&#xA;-N0160F150 KUMIK L603 KOSEK Z74 HAREM T104 ANORA&#xA;-EDDM0150 EDQT&#xA;-PBN/A1)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The above flightplan from EDDL to EDDM validates for FL240, but anything above FL245 will not pass, it will error out with:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;PROF195: KUMIK L603 KOSEK DOES NOT EXIST IN FL RANGE F245..F999&#xA;PROF195: KOSEK Z74 HAREM DOES NOT EXIST IN FL RANGE F245..F999&#xA;PROF197: RS: EDUUFFM14 EDUUFUL13 EDUUNTM13 EDUUTGO13 EDUUSLN13 EDUUWUR14:F245..F255 IS CLOSED FOR CRUISING REF:[EUROED41A] ED AIP(ENR3.3 1 NOTE 9)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;To fly the same flight in higher levels, you would need another routing:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;(FPL-DAXAM-IG&#xA;-A320/M-SDE1FGHIJ1RWXY/LB1&#xA;-EDDL1000&#xA;-N0260F270 DODEN Y853 BOMBI T104 ANORA&#xA;-EDDM0150 EDQT&#xA;-PBN/A1)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This routing works fine for anything above FL245, below it would again error out with:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;PROF195: BOMBI T104 HAREM DOES NOT EXIST IN FL RANGE F000..F245&#xA;PROF204: RS: TRAFFIC VIA DODEN Y853 BOMBI IS ON FORBIDDEN ROUTE REF:[ED2318A] Y853 DODEN BOMBI&#xA;PROF205: RS: TRAFFIC VIA DODEN Y853 BOMBI:F000..F245 IS OFF MANDATORY ROUTE REF:[ED2318B] Y853 DODEN BOMBI&#xA;ROUTE135: THE SID LIMIT IS EXCEEDED FOR AERODROME EDDL [EDDL50120A] CONNECTING TO DODEN&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-01-06T15:58:14.937" LastActivityDate="2015-01-06T15:58:14.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11517" PostTypeId="2" ParentId="751" CreationDate="2015-01-06T15:59:30.830" Score="9" Body="&lt;p&gt;You can land anywhere you want, pretty much.  It all depends, as others have said, on how much of a landing fee you are willing to pay.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases a large major airport really IS most convenient.  My wife and I wanted to visit the Udvar Hazy Air and Space museum during its grand opening in late 2003.  Dulles was still under the ridiculously strict DC ADIZ brought about as a result of an overreaction to 9/11.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the process was well documented by then so we took off from KSNC (Chester) and headed south.  I picked up Flight Following just south of Newark.  (They tend to vector VFR aircraft out to sea in the Newark area, so I just fly over the Class Bravo.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point we were cleared into the ADIZ and were handed off from center to Dulles approach.  The approach controller set me up for a loooong base leg that would roll me out on a 2 or 3 mile final.  Which made sense.  There was no point in putting me in the long procession of commercial aircraft stacked up on 40 mile finals.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;About 20 miles out, approach called me and asked if I could give them 160 knots.  (I flew an RV4, which was a 175 knot aircraft, but had a very low flap speed of 90 knots).  I agreed and pushed the throttle in.  A couple of minutes later, I got a request for 170 knots.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I agreed but told them i would require a &quot;nonstandard&quot; turn to final.  They agreed.  So here I am screaming in at 200 mph in a plane with a 100 mph flap speed set to make a turn to a 2 mile final.  Fun fun fun.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was cleared to land and when the time came I chopped the throttle and rolled into a 100 degree bank with a 4G pull.  When I rolled out I was lined up with the centerline and had bled off 75 mph of speed.  I continued at about 120 kts until I was about 2000 ft from the first turn off and then dropped full flaps and put the plane into a hard forward slip.  We landed about 500 ft before the turn off (we landed on the right runway so the turn off put us between the runways) and I taxi'd tail up to the turn off.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once clear of the runway, approach thanked me for &quot;expediting&quot;.  He said I'd understand in about 20 seconds why he rushed me.  He told me to contact ground on point something, and I did.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;About then a fully loaded 747 roared by on the runway I had just landed on.  Not 150 ft from where I sat.  We taxied to the FBO, tied down and walked to the museum.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later that day I spoke to a friend who flies 747s for Atlas and he explained that a small behind a heavy would require 4 minutes wait for wake turbulence to clear.  With a heavy behind a small, as long as I was clear, the heavy would land.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fun fun fun.  At the time I was flying formation aerobatics so i was on my game.  I was flying 2-3 times a week and very very proficient.  I looked at the request for a nonstandard approach as a fun challenge.  If I ever felt uncomfortable, I would simply reply &quot;unable&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the pilot is in charge of the aircraft.  As I referenced above.  NY approach tends to vector small piston aircraft out to sea.  I had this happen to me exactly once.  When he asked me to turn even further out, I cancelled flight following and bid him a good day.  Eff him.  Ever since then I generally don't call when over NY's class Bravo.  Or if I do, I make sure I'm above 7500 so I can cancel FF if they want me to do anything I don't want to do.  I'm all for working in the system, but I will not be put in danger so that a busy controller can have an easier day.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don&lt;/p&gt;&#xA;" OwnerUserId="5725" LastActivityDate="2015-01-06T15:59:30.830" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11518" PostTypeId="2" ParentId="11514" CreationDate="2015-01-06T16:02:38.063" Score="6" Body="&lt;p&gt;There are variations in how particular airways are used, but there are not routes that are restricted based on the &lt;strong&gt;type&lt;/strong&gt; of operation here in the US, or anywhere that I know of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have pointed out, there may be various restrictions on an airway (route) such as altitude, times of use, directions of use, etc. but they apply the same to GA aircraft as a commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that GA encompasses a wide variety of different types of aircraft, including aircraft that have far less and far more capabilities than commercial aircraft.  Saying that a particular airway is restricted to aircraft flying above 18,000 feet does not restrict it to commercial aircraft, and the entire system is based on a first come first serve concept.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-01-06T16:02:38.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11519" PostTypeId="2" ParentId="8715" CreationDate="2015-01-06T16:10:32.283" Score="13" Body="&lt;p&gt;Airbus has certainly made preliminary plans for a stretched version of the A380 (&lt;a href=&quot;http://www.ausbt.com.au/supersizing-the-superjumbo-1-000-seat-airbus-a380-due-by-2020&quot;&gt;the A380-900&lt;/a&gt;,) but no plans currently exist for that model to go into production. Demand for the A380 has been soft, leading &lt;a href=&quot;https://www.bloomberg.com/news/2014-12-10/airbus-at-crossroads-as-a380-jumbo-faces-spend-or-fade-conundrum.html&quot;&gt;Airbus' own CFO to suggest to investors last month that the A380 might be discontinued entirely&lt;/a&gt; unless they can find enough customers willing to buy a re-engined version of it soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orders for large, quad-engine airliners, including the A380, have been light lately. Since taking the first order 14 years ago and over 7 years since the first delivery, &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Orders_and_deliveries&quot;&gt;only 318 A380s have been ordered&lt;/a&gt;, nearly half of which were from Emirates, and &lt;a href=&quot;http://www.bloomberg.com/news/2014-07-30/airbus-profit-rises-10-as-aircraft-deliveries-increase.html&quot;&gt;many of the A380's orders will likely be cancelled&lt;/a&gt;. While the Boeing 747 has had over 1,500 deliveries over its long lifespan, it, too, currently has a small order book with &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747#Orders_and_deliveries&quot;&gt;only 16 net new orders since 2008&lt;/a&gt;. In contrast, twin-engine wide-bodies have been selling very well lately. The A350 just delivered its first aircraft and already has &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Airbus_A350_XWB_orders&quot;&gt;778 orders&lt;/a&gt;. Similarly, the first 787 was delivered a little over 3 years ago and it has &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Orders_and_deliveries&quot;&gt;1,055 total orders&lt;/a&gt;, so far. The 777X, currently scheduled for production in 2020, was first offered for order a little over a year ago and &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777X#Orders&quot;&gt;already has 286 orders&lt;/a&gt;. Total 777 orders so far &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777#Orders_and_deliveries&quot;&gt;number a whooping 1,807&lt;/a&gt;. The long-haul wide-body market has been trending very strongly towards twin-engine aircraft like the 777, A330, 787, and A350 lately rather than mammoth quad-engine aircraft like the 747 and A380. As such, it seems unlikely that Airbus is going to be sinking billions of dollars into a stretched A380 any time soon.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-01-06T16:10:32.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11520" PostTypeId="2" ParentId="11511" CreationDate="2015-01-06T16:43:35.953" Score="6" Body="&lt;p&gt;The reason its reported as &quot;greater than 6 statue miles&quot; is because 6 statute miles is the equivalent of 10 kilometers. ICAO reports METAR visibility in meters, and reserves 4 places in the coded METAR for the number of meters.  With only 4 places, 9999 is the largest value, and this corresponds to &quot;10km or more.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;http://www.flyingineurope.be/metar_taf_decode.htm&quot;&gt;Aerodrome forecast - TAF  decode&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-06T16:43:35.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11521" PostTypeId="1" AcceptedAnswerId="11838" CreationDate="2015-01-06T20:31:40.500" Score="12" ViewCount="3527" Body="&lt;p&gt;In the question &lt;a href=&quot;https://aviation.stackexchange.com/q/11468/755&quot;&gt;How do non-US pilots get the hours necessary for an ATP?&lt;/a&gt;, the question was raised of whether we have 250 or 500 hour foreign pilots flying airliners into major U.S. airports. &lt;a href=&quot;https://aviation.stackexchange.com/a/11471/755&quot;&gt;DeltaLima's answer&lt;/a&gt; mentioned the &lt;a href=&quot;http://www.icao.int/safety/airnavigation/pages/peltrgfaq.aspx#anchor24&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Multi-Crew Pilot License (MPL)&lt;/a&gt;, which&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;allows a pilot to exercise the privileges of a co-pilot in a commercial air transportation on multi-crew aeroplanes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of particular interest is the large gap in the minimum experience requirement between this license and an ATP license that would normally be required to fly an airliner in the U.S. While the FAA normally requires airline pilots to have at least 1,000 flight hours (or 1,500 if they don't have a degree in aviation,) the requirement for the ICAO MPL standard is much less. &lt;a href=&quot;http://www.icao.int/safety/airnavigation/pages/peltrgfaq.aspx#anchor24&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to ICAO&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ICAO Standard for the MPL specifies 240 hours as the minimum number of actual and simulated flight hours performing the functions of the pilot flying and the pilot non-flying.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the U.S. has no such pilot certificate, what I'm wondering is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Is a pilot who receives an MPL from another country allowed by the FAA to fly an airliner on normal scheduled passenger service routes into major U.S. airports?&lt;/strong&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;If so, are there any further restrictions on doing so?&lt;/strong&gt; For instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can they fly a route subject to ETOPS regulations into the U.S.?&lt;/li&gt;&#xA;&lt;li&gt;Can they fly a 777 into the U.S. or are they limited to smaller aircraft (e.g. turboprops and the like?)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2845/755&quot;&gt;What is required for a pilot to fly in another country?&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/183/755&quot;&gt;I have a European EASA license - what do I need to do to be allowed to fly in the US?&lt;/a&gt; cover some general points about the certification requirements to fly an aircraft in a country other than the one where the pilot obtained their license, but they don't address issues specific to flying airline routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, &lt;a href=&quot;http://www.icao.int/safety/airnavigation/pages/peltrgfaq.aspx#anchor06&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO seems to suggest&lt;/a&gt; that pilots with an MPL would indeed be able to fly in the right seat of an airliner into any ICAO country:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;International recognition of flight crew licenses &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Convention on International Civil Aviation, often called the Chicago Convention, provides for worldwide recognition of flight crew licences issued by any member State of the International Civil Aviation Organization (ICAO) provided that:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;1.the licence meets or exceeds the ICAO licensing Standards of Annex 1 – Personnel Licensing to the Convention on International Civil Aviation; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;2.the licence is used on an aircraft which is registered in the State which has issued or validated the licence.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;If the licence is to be used on an aircraft which is not registered in the issuing State, the licence holder must obtain a validation of the licence from the State of Registry or alternatively obtain a new licence issued by the State of Registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Can someone provide a reference to the FARs (or something of similar authority) or cite personal experience to confirm whether this is indeed allowed and, if so, what restrictions are placed on such operations?&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2020-02-08T13:53:22.003" Title="Can a pilot with an ICAO Multi-Crew Pilot License fly an airliner into the U.S.?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;icao&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11522" PostTypeId="1" AcceptedAnswerId="11523" CreationDate="2015-01-06T21:34:08.283" Score="1" ViewCount="476" Body="&lt;p&gt;What happens to an airplane when hit by lightning?&lt;/p&gt;&#xA;" OwnerUserId="5729" LastEditorUserId="8730" LastEditDate="2016-01-31T21:23:07.800" LastActivityDate="2019-11-13T20:48:15.073" Title="What happens when lightning strikes an airplane?" Tags="&lt;aircraft-design&gt;&lt;accidents&gt;&lt;aircraft-failure&gt;&lt;lightning&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-01-06T21:57:50.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="11523" PostTypeId="2" ParentId="11522" CreationDate="2015-01-06T21:56:50.670" Score="-2" Body="&lt;p&gt;Since the aircraft is not grounded, the physics are the same as with a car that gets struck by lightning. The aircraft's skin will be charged, but very little current will be induced in internal parts in the process. The outer skin will act as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Faraday_cage&quot; rel=&quot;nofollow noreferrer&quot;&gt;Faraday cage&lt;/a&gt; and protect the inner parts from the electric field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is greatly helped by a metal structure. Composite aircraft parts need a copper mesh over all external surfaces to give them sufficient electrical conductivity. The terminals of that mesh must be connected to the metal parts of the structure to make sure that all parts will have the same electrical potential in case of lightning strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the ionized air caused by lightning will leave burn marks on the surface, and an inspection of the affected part and the electrical equipment is advisable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-11-13T20:48:15.073" LastActivityDate="2019-11-13T20:48:15.073" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="11524" PostTypeId="2" ParentId="888" CreationDate="2015-01-06T22:46:25.817" Score="10" Body="&lt;p&gt;Airplanes are designed to withstand lightning strikes, since they are expected to experience this in service. The goal is to conduct the current through the airplane while minimizing any damage this will cause.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Metal parts are naturally conductive, but composites need a conductive layer such as a metal mesh added to conduct the current. The parts also need to be connected, or the current will arc across the gap, possibly damaging both parts or sparking a fire. This connection can either be through properly installed fasteners like bolts or rivets, or through the use of bonding jumpers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel and electical systems in the aircraft require special attention. In the fuel tanks, parts must be connected well without gaps to avoid sparks that could ignite fuel vapors. Electrical systems must be sufficiently isolated to prevent lightning current from damaging them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot;&gt;As this Boeing information shows&lt;/a&gt;, the protection required also depends on the location in the airplane. Different parts generally experience lightning strikes in different ways, and need different approaches in design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing page also includes a flowchart for deciding whether a system needs to be inspected after a lightning strike. If the system was not used after the strike, it should be checked. If the system was used after the strike, it only needs to be checked if the system had anomalies in flight or of there is damage near the antennas for that system.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="595" LastEditDate="2015-06-15T12:45:20.507" LastActivityDate="2015-06-15T12:45:20.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11525" PostTypeId="1" AcceptedAnswerId="11547" CreationDate="2015-01-07T00:19:21.377" Score="7" ViewCount="3987" Body="&lt;p&gt;Why do airplane rental companies charge per flight hour (using hobbs time), instead of either MX hours (tach time) &lt;em&gt;or&lt;/em&gt; based on the amount of fuel used?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't a 3-hour long cross-country flight be much cheaper than three hours spent in pattern work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, rental rates would seem more logical if they are based on MX time.&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="64" LastEditDate="2015-01-09T22:47:04.603" LastActivityDate="2015-01-09T22:47:04.603" Title="Why do small aircraft rentals charge per flight hour?" Tags="&lt;rental&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11527" PostTypeId="1" AcceptedAnswerId="11528" CreationDate="2015-01-07T03:45:11.540" Score="44" ViewCount="21085" Body="&lt;p&gt;What are some of the differences between piston engines used in aircraft and automobiles?  It seems aircraft engines are much more expensive, I imagine some of that cost must be due to the more extreme environment (temperature, air density, roll angle) that an aircraft engine is expected to run in.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are aircraft engine parts expected to be less likely to fail?&lt;/li&gt;&#xA;&lt;li&gt;What is done to allow the engine to function at extreme temperatures / altitudes / air densities?&lt;/li&gt;&#xA;&lt;li&gt;Do changes have to be made to allow a piston engine to function while upside down (in a roll)?&lt;/li&gt;&#xA;&lt;li&gt;What components are different on an aircraft vs automotive piston engine (magnetos vs. spark plugs, oil system)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5730" LastEditorUserId="572" LastEditDate="2015-02-25T07:30:16.173" LastActivityDate="2019-09-17T14:40:26.223" Title="What are some of the differences between piston engines used in aircraft and automobiles?" Tags="&lt;piston-engine&gt;&lt;altitude&gt;&lt;temperature&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11528" PostTypeId="2" ParentId="11527" CreationDate="2015-01-07T06:06:48.253" Score="74" Body="&lt;p&gt;The engine in a typical light airplane (say a Cessna 172 or a Piper Cherokee) has a lot in common with the engine in a &lt;a href=&quot;http://en.wikipedia.org/wiki/Volkswagen_Beetle&quot;&gt;classic 1960s VW Beetle (Type 1)&lt;/a&gt;: Both engines are horizontally opposed four-stroke four-cylinder spark ignition gasoline engines. Their parts even have similar metallurgy, and broadly similar failure rates.&lt;br&gt;&#xA;In fact if you remove the gearbox and install a magneto ignition system &lt;a href=&quot;http://www.eaa.ca/experimenter/articles/2010-02_powerplants.asp&quot;&gt;you basically have one of several &quot;Volkswagen aircraft engines&quot;&lt;/a&gt; that are popular in the experimental market, and have proven to be &lt;em&gt;very&lt;/em&gt; reliable if well-maintained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Certificated&lt;/em&gt; aircraft engines (the Lycoming and Continentals you would find in our hypothetical Piper or Cessna) have a few other features not found on a Volkswagen engine: They have dual ignition systems (two magnetos, two spark plugs per cylinder) for redundancy in case one fails, and an oil sump designed to hold at least twice the capacity of oil needed for safe operation. They typically also have a manual mixture control to allow the pilot to lean the fuel/air mixture as they climb (the VW Beetle generally didn't get too high above sea level, and when they did the local mechanic could adjust the mixture in the garage because those cars would probably stay at a relatively high altitude for most of their life - aircraft have an annoying habit of climbing and descending &lt;em&gt;a lot&lt;/em&gt;, so either a manual mixture control or an &lt;em&gt;altitude-compensating&lt;/em&gt; carburetor is necessary).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what accounts for the price difference? Three things: FAA Certification, Volume, and Liability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA Certificated engines cost quite a bit of money: The manufacturer needs to thoroughly document their design and manufacturing practices, and ensure the engine meets the design requirements and can pass the tests described in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.33&amp;amp;rgn=div5&quot;&gt;FAR 33&lt;/a&gt;. Doing (and documenting) all of this to the FAA's satisfaction is not a small burden, and it adds to the cost of the final product.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Volume is the next problem: As a reward for complying with Part 33 and getting your engine certified you now have the opportunity to sell your engine. To a very small market. There are far fewer piston aircraft than cars, and although piston aircraft engines are often &quot;worn out&quot; over the life of an airframe most owners overhaul their engines rather than replacing the whole engine outright. As a result the volume of new engine production is relatively low (and with relatively brisk competition in the overhaul market the manufacturer isn't even guaranteed a substantial amount of &lt;em&gt;that&lt;/em&gt; business). As with any other product, when volume is small price goes up to allow a profit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Liability is the last (and probably largest) factor affecting pricing: Jane Q. Pilot is flying along in his brand new just-off-the-production-line Cessna with her two kids and the family dog when the engine fails. She is unable to make a successful landing, and everyone dies, whereupon her bereaved and distraught husband John immediately sues the mechanic who last worked on the plane, Cessna (who made the airframe), and Lycoming (who made the engine).&lt;br&gt;&#xA;Being ready to deal with this kind of high-profile and high-cost event requires a substantial legal team (the cost of which is built into each engine sold), and as the manufacturer is accepting a substantial risk the price gets bumped a bit more to provide a balancing reward (profit).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So to answer your bullet-pointed questions which I largely ignored in the explanation above:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Are aircraft engine parts expected to be less likely to fail?&lt;/strong&gt;&lt;br&gt;&#xA;We may have this expectation given the price tag, but in reality they're probably about as reliable as any other well-maintained air-cooled 1960s engine design.  A modern car engine has a number of design and technological advantages over the typical piston aircraft engine, and if we equipped them with dual independent ignition systems and gave them the kind of maintenance aircraft engines get they may well beat aircraft engines in terms of reliability. (Of course a modern car engine also weighs a lot more than a typical aircraft engine, so some money would have to be spent making it lighter without sacrificing that reliability.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What is done to allow the engine to function at extreme temperatures / altitudes / air densities?&lt;/strong&gt;&lt;br&gt;&#xA;Surprisingly little: The addition of a mixture control for the carburetor, dual independent ignition systems, and a healthy weight consciousness pretty much covers it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Do changes have to be made to allow a piston engine to function while upside down (in a roll)?&lt;/strong&gt;&lt;br&gt;&#xA;Yes (the fuel and lubrication systems for need to be designed to handle zero / negative G loads for an extended period of time), but your typical piston aircraft engine isn't designed to function while upside down: Aerobatic aircraft engines are a slightly different beast, and they cost a little more than their non-aerobatic counterparts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What components are different on an aircraft vs automotive piston engine (magnetos vs. spark plugs, oil system)?&lt;/strong&gt;&lt;br&gt;&#xA;The biggest difference between a 1960s VW engine on a classic Beetle and a 2015 Lycoming O-320 is the dual magneto ignition system. The rest of the parts are largely identical, or at least analogous: Spark plugs look like spark plugs, cylinders look like cylinders, carburetors look like carburetors, etc.&lt;br&gt;&#xA;Aircraft engines are also designed for component swaps: Cylinders can be easily unbolted and replaced for example, as can the magnetos, the oil pump, the carburetor, the starter, etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-01-07T07:55:51.677" LastActivityDate="2015-01-07T07:55:51.677" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11530" PostTypeId="2" ParentId="11506" CreationDate="2015-01-07T11:50:10.143" Score="6" Body="&lt;p&gt;Just to add a little perspective, route-free airspace has been in consideration for a while and is already implemented in certain countries. The route-free or direct-routing concept makes use of the currently underutilized satellite systems on aircraft (In the routing context) and intelligent software to execute more efficient routing of aircraft (GPS-based). Direct-routing is also a part of the the &lt;a href=&quot;http://www.nats.aero/environment/consultations/pc-route-free-airspace/&quot; rel=&quot;noreferrer&quot;&gt;NATS UK&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Next_Generation_Air_Transportation_System&quot; rel=&quot;noreferrer&quot;&gt;the FAA's NextGen&lt;/a&gt; air traffic management strategy.  &lt;/p&gt;&#xA;" OwnerUserId="4435" LastEditorUserId="1696" LastEditDate="2015-01-07T15:20:48.037" LastActivityDate="2015-01-07T15:20:48.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11531" PostTypeId="2" ParentId="11527" CreationDate="2015-01-07T12:08:12.977" Score="19" Body="&lt;p&gt;To add some more aspects to voretaq7's answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane engines have a very different operating point than car engines. This makes it impossible to simply plug a car engine into an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft piston engines have a max. RPM of 2700. Since they are normally directly coupled to the propeller, a higher engine speed would reduce propeller efficiency. Light aircraft are now fitted with &lt;a href=&quot;http://www.flyrotax.com/products.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;small geared piston engines&lt;/a&gt; which reach up to 5000 RPM, but your regular Cessna or Piper will still have the conventional, ungeared engine. Note that the now almost 80 year old &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Merlin&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce Merlin&lt;/a&gt; was run at 3000 RPM.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft engines run near their rated performance for hours. Cruise setting is normally between 65% and 75% of maximum power, whereas your regular car engine will see this kind of power setting only for a few seconds at a time. Even when driving on the Autobahn, a car engine will maybe deliver 30% of its maximum power or less most of the time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Car engines have now plenty of computer control: The ignition point, the mixture and (in some cases) the valve timing can be adjusted for the specific operating point. All these parameters are either fixed, or, in case of mixture, need to be manually adjusted in aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Points 1 and 3 mean that you cannot compare car and aircraft engines of the same rated power output directly. The higher engine speed and the better adaption translates into much higher power ratings for car engines, but point 2 means that the rated power cannot be delivered when used in an aircraft. If a car engine is run near its rated power for an extended time, it needs a better cooling system. Even then, its components are not designed for these loads and will fail earlier than the corresponding parts of an aircraft engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, due to the much higher number of car engines in operation, we have much better data on the long-time behavior of all parts and much more R&amp;amp;D effort is spent on optimizing them. When run as intended, car engines are now much more reliable than ungeared aircraft engines, even though they have a higher parts count (see point 3 above). Basically, ungeared piston aircraft engines are living museum pieces. The much smaller market size for new aircraft engines is one reason, but the other is the very extensive certification effort which is needed before a newly developed engine can be used in an aircraft. This is necessary to ensure a low failure rate, but has at the same time effectively stopped technological progress to trickle down to aircraft piston engines for half a century.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electronic ignition systems allow any modern car engine to run upside down, but the oil system needs gravity for the oil to be collected and kept in circulation. For a short time, modern car engines need no modification to run upside down, only the fuel system would need to be adapted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature extremes for which car engines are tested are more severe than those of airplane engines. Car engines are expected to work at all elevations, so they are designed for similar density variations. Only in extreme cases will an aircraft engine fly higher than the &lt;a href=&quot;http://en.wikipedia.org/wiki/Extreme_points_of_Earth#Highest_attainable_by_transportation&quot; rel=&quot;nofollow noreferrer&quot;&gt;elevation of the highest roads&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Regulation&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Lawyers&lt;/strong&gt; and&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Market size&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;drive the price of aircraft engines up. If they would be expected to work at the environmental extremes that car engines are designed for, they would be even &lt;strong&gt;more&lt;/strong&gt; expensive.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-11-28T20:45:00.920" LastActivityDate="2016-11-28T20:45:00.920" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11532" PostTypeId="2" ParentId="11506" CreationDate="2015-01-07T12:34:28.920" Score="2" Body="&lt;p&gt;It's like a lot of systems that evolve.  If we started today, we might do it differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The analogy with cars is a poor one because, for the most part, there are a very small number of aircraft in a very large amount of airspace and it would be hard to justify the use of airways.  So starting from the standpoint that every aircraft accurately knows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) Its location, heading, velocity vectors, fuel data, flight constraints and destination etc;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) The same information for all other aircraft in its vicinity (this could cover quite a large volume in practice);&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) The terrain and weather conditions etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then it becomes a really interesting combinational problem to solve in the context of an autonomous distributed computer system; i.e. no ATC - all handled by cooperating in-flight systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearly there are significant points where paths must cross because of the geographical positions of airports, and of course the dynamic scheduling of arrivals and departures at airports; not to mention the handling of unexpected events.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a computer scientist this is all fascinating and a meaty challenge, but I suspect that it would be very difficult to develop a system of autonomous control based on this approach to the point that it could be trusted!&lt;/p&gt;&#xA;" OwnerUserId="6737" LastActivityDate="2015-01-07T12:34:28.920" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11533" PostTypeId="2" ParentId="11525" CreationDate="2015-01-07T12:36:37.487" Score="6" Body="&lt;p&gt;The fuel-to-air mixture in aircraft piston engines is &lt;a href=&quot;http://www.experimentalaircraft.info/articles/aircraft-engines-leaning.php&quot;&gt;mostly set with manual controls&lt;/a&gt;. A lean mixture will result in higher cylinder head temperatures and increase the risk of detonation, preignition and overheating of exhaust valves. This means that a pilot who is charged according to fuel consumption will use a different mixture setting than a pilot who is charged by the hour. To conserve fuel, the mixture can be set leaner than what would be best for preserving the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, piston aircraft are charged by the hour to generate the right incentives for setting the fuel-to-air mixture. Also, as ratchet freak mentions correctly in the comments, the secondary cost are mostly proportional to operating time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-01-07T12:36:37.487" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11534" PostTypeId="1" AcceptedAnswerId="11535" CreationDate="2015-01-07T12:52:03.837" Score="1" ViewCount="793" Body="&lt;p&gt;Since I have flown in aicraft as a kid, there was a sound audible when the aircraft is on ground (before taking off or after landing) which is similar to the sound a DJ does when he scratches the disks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for the wird example, but I do not know how to explain it better. It is like the scratching of a disk and the sound starts at a higher pitch and it ends at a lower pitch. I am really interested in finding out what it is and why it happens, since I have never been able to find out how it is produced.&lt;/p&gt;&#xA;" OwnerUserId="4358" LastEditorUserId="572" LastEditDate="2015-01-07T13:13:40.990" LastActivityDate="2015-01-07T13:13:40.990" Title="What is the scratching sound produced by aircraft on the ground (taxi-in/taxi-out)?" Tags="&lt;commercial-aviation&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-01-07T15:09:41.440" ContentLicense="CC BY-SA 3.0" />
  <row Id="11535" PostTypeId="2" ParentId="11534" CreationDate="2015-01-07T12:59:22.983" Score="4" Body="&lt;p&gt;There is a variety of sounds an aircraft can produce, some even depending on the type of aircraft you are sitting in. Without any further data or reference, the most likely events that you can hear during pushback, taxi or vacating the runway are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cargo Doors being shut and locked&lt;/li&gt;&#xA;&lt;li&gt;Flaps being extended to take-off position&lt;/li&gt;&#xA;&lt;li&gt;Flaps being raised after landing&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are many more things that you can hear from the cabin, so without further information, it will be difficult to pin-point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option, if it was predominantly on Airbus aircraft, is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Power_transfer_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;Power Tranfer Unit&lt;/a&gt;, which is described to sound like a &lt;a href=&quot;http://www.askthepilot.com/questionanswers/the-barking-dog-airbus-noises/&quot; rel=&quot;nofollow noreferrer&quot;&gt;barking dog&lt;/a&gt; or &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20110119224359AA1YARe&quot; rel=&quot;nofollow noreferrer&quot;&gt;like a drill&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this question and the answers:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/137/what-is-this-sound-from-airbus-aircraft-before-take-off/139#139&quot;&gt;What is this sound from Airbus aircraft before take off?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-01-07T13:05:25.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11536" PostTypeId="1" AcceptedAnswerId="11538" CreationDate="2015-01-07T16:04:46.033" Score="34" ViewCount="4268" Body="&lt;p&gt;While practicing for my commercial certificate in a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot;&gt;T-tail Piper Arrow IV&lt;/a&gt;, I put the gear down on downwind, and one green light didn't come on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the right seat was a CFII/Multi, who had over 1,000 hours but less than 10 hours in Pipers, whereas I had about 300 hours, and over 200 in Pipers, having done my PPL in stiff-legged Cherokees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a certificated pilot, I was PIC, but we talked about how to handle the emergency, and the CFI and I decided that since I had so much more experience in Pipers, I would handle the emergency tasks, while he handled the radios and looked for traffic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We did the proverbial tower fly by (although they wouldn't say anything except the gear &quot;appeared to be down&quot;), and they cleared me to land on any runway. Our landing was uneventful, and it turned out to be an electrical MX issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we landed, however, the flight school nearly fired the CFI for not having taken control of the aircraft during the emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did we make the right decision for me to handle the emergency? Or should I have let the CFI/CFII/MEI with over 1,000 take over as PIC and handle the airplane?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-01-07T16:33:48.793" LastActivityDate="2015-03-10T17:04:08.330" Title="Who should handle an emergency when there's both a certificated pilot and a CFI on board?" Tags="&lt;flight-training&gt;&lt;emergency&gt;&lt;general-aviation&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11537" PostTypeId="2" ParentId="11536" CreationDate="2015-01-07T16:17:56.120" Score="23" Body="&lt;p&gt;I don't see a mistake on the part of the CFI. After all, you were in the left seat and legally cleared to fly the aircraft, so it is up to you to decide. By clearly communicating and sharing the workload you did the right thing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess the reason why the CFI got in trouble had more to do with insurance issues than with regulations. You don't mention it, but I assume the CFI was employed by the owner of the aircraft. It would be easier for the owner to settle with the insurance company if one of his employees is PIC in an emergency.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-01-07T16:17:56.120" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11538" PostTypeId="2" ParentId="11536" CreationDate="2015-01-07T16:37:38.640" Score="35" Body="&lt;p&gt;From a safety perspective &lt;em&gt;both&lt;/em&gt; pilots should be handling any emergency that arises, each working to their individual strengths and expertise to ensure a safe outcome.&lt;br&gt;&#xA;&lt;strong&gt;&lt;em&gt;This is exactly what you did&lt;/em&gt;&lt;/strong&gt; in the scenario you describe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of who calls the shots (acts as PIC for the emergency), generally the most qualified pilot onboard should be the one giving the orders. Deciding who that is falls to the pilots onboard (because they're the ones who will arrive at the scene of any resulting accident first).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So in my mind the question really is &quot;How do I determine who is most qualified?&quot; -- Any opinion we can give here comes &lt;em&gt;dangerously close to second-guessing your emergency actions&lt;/em&gt; which is something I personally try to avoid, but I'm going to embellish your scenario above for illustrative purposes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;The Instructor&lt;/strong&gt;&lt;br&gt;&#xA;Former air force pilot ATP, CFI/CFII, MEI.&lt;br&gt;&#xA;10,000 hours in various jets, 10 hours in an Arrow (doing this instructing gig.) and for the sake of argument no other time in PA-28s.  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;You&lt;/strong&gt;&lt;br&gt;&#xA;PPL + Instrument Rating, working on your Commercial.&lt;br&gt;&#xA;300 hours, 200 in fixed-gear PA-28s and let's say 20 in Arrows.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'll further assume you both kept your cool and didn't panic (because if either of you turned into a quivering blob that would automatically disqualify them from taking control of the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we go by the certificates, your instructor is certainly &quot;more qualified&quot; - and in 10,000 hours they've probably dealt with more real-world emergencies than you have.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we go by &quot;time in type&quot; and experience flying PA-28 variants you're clearly more familiar with the general type, and possibly this specific aircraft &amp;amp; systems (like the emergency gear extension system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the above, having you handle the controls seems to be the most logical course of action. The CFI can do &quot;everything else&quot; - communication, traffic scan, calling out checklists &amp;amp; altitudes, etc. - to ensure that you can concentrate on flying the plane and landing as safely as possible.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-07T16:37:38.640" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11539" PostTypeId="1" AcceptedAnswerId="11541" CreationDate="2015-01-07T17:13:49.543" Score="15" ViewCount="1179" Body="&lt;p&gt;To the Northwest of the KMCI Class B airspace, there is a strange cut out in SFC/80 airspace, which I highlighted at &lt;a href=&quot;http://bit.ly/1BLM3Hi&quot; rel=&quot;noreferrer&quot;&gt;this link&lt;/a&gt; (&lt;em&gt;and shown in picture below&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VOnKi.png&quot; alt=&quot;KMCI&quot;&gt;&lt;br/&gt;&#xA;&lt;em&gt;highlighted in purple - Image Source: www.skyvector.com&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no airport there, and no obvious reason for the cut out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What possible reasons could there be for a strange shape like this?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="65" LastEditDate="2015-01-07T19:00:48.020" LastActivityDate="2018-09-26T17:49:47.313" Title="What is this strange cutout in Class B of Kansas City International Airport?" Tags="&lt;airspace&gt;&lt;class-b-airspace&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11541" PostTypeId="2" ParentId="11539" CreationDate="2015-01-07T17:37:28.167" Score="11" Body="&lt;p&gt;There are in fact two airports in the cutout:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LfpTF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;An unmarked field (&lt;strong&gt;&lt;em&gt;A&lt;/strong&gt; in top map&lt;/em&gt;) just east of Platte City (see below) that corresponds to the NW limit of the cutout. &lt;em&gt;Note that this edge of the cutout appears to parallel the main runway at MCI.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vUilU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;The private &lt;a href=&quot;http://www.airnav.com/airport/7MO5&quot; rel=&quot;noreferrer&quot;&gt;Elton Field&lt;/a&gt; (&lt;strong&gt;&lt;em&gt;B&lt;/strong&gt; in top map&lt;/em&gt;). &lt;em&gt;In the image below, field is boxed in red and runway in blue.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vHeje.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And there's also the VFR reporting point over north Platte City&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-01-07T22:16:06.450" LastActivityDate="2015-01-07T22:16:06.450" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11542" PostTypeId="2" ParentId="11527" CreationDate="2015-01-07T17:38:02.020" Score="8" Body="&lt;p&gt;One point that seems to be missing from excellent answers provided so far is carb heat. &lt;a href=&quot;http://en.wikipedia.org/wiki/Carburetor_icing&quot;&gt;Carburetor icing&lt;/a&gt; is a concern for most if not all carbureted aircraft. The small planes I've flown (Cessna 152/162/172) all have a manual &lt;a href=&quot;http://en.wikipedia.org/wiki/Carburetor_heat&quot;&gt;carb heat&lt;/a&gt; knob. When you engage it, the engine's air intake is switched over to air that has been warmed by the exhaust. This is designed to melt ice that may be blocking the carburetor or to prevent the ice from forming in the first place.&lt;/p&gt;&#xA;" OwnerUserId="6741" LastActivityDate="2015-01-07T17:38:02.020" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11543" PostTypeId="2" ParentId="11536" CreationDate="2015-01-07T18:05:32.373" Score="14" Body="&lt;p&gt;The instructor did the right thing by letting you fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have 1200 hrs on the 737-300, 120 hrs 737-200, approx. 150 hours on the C172 and 80 hours approx Seneca (both a while ago), and a fATPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I were in the Cockpit with somebody with more familiarity of the a/c characteristics I'd do Radio and assist as well, leaving them as PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no time for an ego here.&lt;/p&gt;&#xA;" OwnerUserId="6743" LastEditorUserId="65" LastEditDate="2015-01-08T15:22:13.600" LastActivityDate="2015-01-08T15:22:13.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11544" PostTypeId="2" ParentId="11527" CreationDate="2015-01-07T18:55:43.897" Score="7" Body="&lt;p&gt;No or very limited emissions control on the aircraft, at least compared to new cars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft engines have a rough time with shock cooling.  Cruising at 75% power for hours, then slam the throttle shut and descend, fast.  Shock cooling can crack engines.  Auto engines would not survive very long.  It would be like running an auto engine at full blast on a dyno for a couple hours (as if an auto engine would survive that first step, LOL) and then blasting it with icy fire hose water, like taking hot plate out of oven, toss into icy dish washing water, it shatters.  Even carefully engineered aircraft engines have problems with this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to fuel pump vapor lock on fuel injected engines, aircraft are about as bad as 80s cars.  Its not really a significant problem under most conditions for most aircraft most of the time, but its sometimes pretty hard on a hot summer day to get liquid gas into the engine to start it.  Ground vehicles work around the problem by having the refinery blend winter or summer gas, but planes can fly from the arctic to the tropics in hours, so its not so simple for planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft have multiple, usually manually selected, fuel tanks.  Many pilots have died by being overly cavalier about toggling from tank to tank in circumstances where a failure would be fatal.  Very few cars or trucks have more than one gas tank.  Fuel tank piping can be extremely complicated on larger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft fuel is not blended with ethanol so water does not mix with the ethanol like it does in automotive E90 type fuel.  What that means is part of preflight is draining a little (like a cup) of fuel out of the tanks, until no water comes out of the fuel tanks.  You're not suppose to just dump that fuel out on the ground to evaporate, but ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is nothing like the ODB-II car standard for planes.  There is no universal plug on all aircraft currently flying where all computer test sets ever made can talk to the engine computer about engine performance.  Such things DO exist for specific engines and specific aircraft but a universal world wide standard does not exist for engine test sets and engine computers in aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many aircraft engines are air cooled and its not unusual for performance stats to vary such that the cylinders in back run hotter than the cylinders in front because they sit in air heated by the cylinders in front of them.  People used to water cooled car engines are sometimes surprised by this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often variable pitch props are operated by engine oil pressure.  Usually car/truck transmissions use special transmission fluid in their transmissions and power steering/brakes.  I think some (all?) motorcycles use engine oil in their transmissions.  There do exist variable pitch propellers that use hydraulics not engine oil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Car engines heat the car using circulating water.  Aircraft engines, being air cooled, usually heat the aircraft using a heat exchanger gadget off the exhaust.  Obviously a leak would be rather dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a stereotype that all cars use multi-grade engine oil, and all aircraft use single grade oil.  That is strictly false but true enough, often enough, that it'll be claimed as fact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I edit to add in a meta commentary that all 2015 car engines are virtually the same, and the diversity level of aircraft and aircraft engines is dramatically higher.  If you look at a random 2015 car, its engineering is probably roughly identical to any other randomly selected 2015 car.  But seemingly all aircraft are different.  So its easy to talk about car engines but hard to nail down aircraft engines)&lt;/p&gt;&#xA;" OwnerUserId="1971" LastEditorUserId="1971" LastEditDate="2015-01-07T19:01:28.760" LastActivityDate="2015-01-07T19:01:28.760" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11545" PostTypeId="2" ParentId="11527" CreationDate="2015-01-07T19:25:54.807" Score="7" Body="&lt;p&gt;An aircraft is pulled thru the air by the crankshaft of the engine, and automotive engines aren't designed to have any load pushing or pulling on the crank.&lt;br&gt;&#xA;Most if not all aircraft engines have a big thrust bearing to handle this, so auto engine conversions use a reduction drive with a thrust bearing for pulling/pushing the aircraft, or if direct-drive change out the bearings in the engine with one designed to handle the forces involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another major difference between automotive and aircraft engines is the power curve: The Horsepower and Torque value of an aircraft engine run almost parallel lines, whereas in most automotive engines the torque peaks in the low RPM range and horsepower in the high RPM range (for stop-and-go driving, varying speeds, etc.).  An aircraft engine is run more like a stationary application like you would have with a generator or irrigation pump etc.&lt;br&gt;&#xA;If an automobile engine were utilized in this fashion it would far exceed the life of most aircraft engines. Why? Air cooled verses liquid cooling. A Liquid cooled engine maintains a constant temperature at all times. An air cooled engine does not. You will not witness a dive from a high altitude in a general aviation aircraft where you chop the power and point the nose at the ground. If you were to try this There is a very good chance you would have some stuck valves when you tried to come back in with the power. Could turn into a bad day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last thing: I don't believe a modern well designed engine needs two ignition systems. In all my years of flying I never or have ever heard of any type of ignition failure. When a pilot  is doing a run up before takeoff and does a mag check, the reason you get that 50 rpm drop is because that combustion chamber is not very well designed. You don't need two magnetos.&lt;br&gt;&#xA;One thing is certain on any power plant be it auto or aircraft: the less moving parts you have, the better off you'll be. As stated before,the aircraft engine manufactures are held back by the cost of being STC'd from FAA regs. Which in turn hinders development. Many new ideas have come from the home built crowd.&lt;/p&gt;&#xA;" OwnerUserId="6745" LastEditorUserId="64" LastEditDate="2015-01-08T02:54:34.433" LastActivityDate="2015-01-08T02:54:34.433" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11546" PostTypeId="2" ParentId="11506" CreationDate="2015-01-07T20:01:53.507" Score="4" Body="&lt;p&gt;Speaking as a GA pilot flying light airplanes in the US system:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On flights in lower use airspace, at lower altitudes, and with the appropriate ATC controls in place (agreements allowing controllers to do that across into someone else's airspace) it's possible to get a filed GPS direct route approved.  I've done so on trips in the 200-300 mile range before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On longer trips, you don't necessarily have to use the airways.  It's often possible to get waypoints at the ingress/egress of airspace, which you can go direct between (off airway).&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2015-01-07T20:01:53.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11547" PostTypeId="2" ParentId="11525" CreationDate="2015-01-07T20:46:53.143" Score="8" Body="&lt;p&gt;In the US most General Aviation rentals are &quot;Wet Hobbs Time&quot; -- You are billed based on the actual clock time the engine was running (in tenths of an hour), and fuel/oil are included in the rental price.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is attractive to renters because of the simplicity: You don't have to pay the FBO separately for the fuel, oil, and aircraft, and you're basically paying for the amount of &quot;clock time&quot; you spent in the plane.&lt;br&gt;&#xA;It's easy to understand, especially for new students who may not quite grasp the concept of how the recording tachometer measures &quot;time&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hobbs billing is attractive to the FBO as well, for different reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rentals are typically blocked out by clock hours (&quot;10 AM to 2 PM&quot;).&lt;br&gt;&#xA;Since booking is clock time billing based on clock time (Hobbs hours) makes sense.  &lt;/li&gt;&#xA;&lt;li&gt;In practice the two numbers are usually close (and when they're not the error tends to favor the FBO).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Let's look at your &quot;Tach vs. Hobbs&quot; scenarios (for the sake of simplicity let's assume both flights are three &quot;clock hours&quot; chock-to-chock):&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Pattern Work&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Pattern work consists of three basic phases: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Takeoff (full throttle, high RPM - Tach runs faster than Hobbs)&lt;/li&gt;&#xA;&lt;li&gt;Circuit (low power, low RPM - Tach runs slower than Hobbs)&lt;/li&gt;&#xA;&lt;li&gt;Descent &amp;amp; Landing (near idle power, very low RPM - Tach runs &lt;em&gt;MUCH&lt;/em&gt; slower than Hobbs)&lt;br&gt;&#xA;There might be a taxi in there for full-stop practice, but you'll be close to idle there too.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If we average this out over three hours of pattern work (and assuming you and your instructor don't commit suicide to break the monotony) the Tach hour meter will be reading a number much lower than the Hobbs meter.&lt;br&gt;&#xA;In this scenario you might have 2.25 tach hours for your 3 Hobbs / Clock hours.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;3-hour Cross Country&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A cross country consists of 5 phases:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Takeoff/Climb (full throttle, high RPM - Tach runs faster than Hobbs)&lt;/li&gt;&#xA;&lt;li&gt;Cruise (moderate throttle, moderate RPM - Tach and Hobbs run about the same speed)&lt;/li&gt;&#xA;&lt;li&gt;Descent (moderate-low throttle, moderate-low RPM - Tach may be a bit slower than Hobbs)&lt;/li&gt;&#xA;&lt;li&gt;Circuit/Approach (low power, low RPM - Tach runs slower than Hobbs)&lt;/li&gt;&#xA;&lt;li&gt;Landing (near idle power, very low RPM - Tach runs &lt;em&gt;MUCH&lt;/em&gt; slower than Hobbs)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If we assume Phases 1 and 3 take about the same time they roughly cancel each other out. Phase 2 (Cruise) is a wash too, so we're left with two brief periods where the tach is running noticeably slower than the Hobbs (the pattern and landing at the destination).&lt;br&gt;&#xA;In this scenario you might have 2.85 Tach Hours for your 3 Hobbs / Clock hours.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In both of these scenarios the FBO comes out ahead of the game -- they're billing you for 3 hours of time, but their maintenance cycle is based on the tach. This might be enough to squeeze another day or two of profitable flying out of an airframe before it's next annual or 100-hour inspection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are scenarios where you can &quot;beat&quot; the Tach clock, but most of them involve being downright abusive to the aircraft/engine. For example if you flew that 3 hour cross country at low altitude and full throttle (very high RPM) you might rack up 3.3 tach hours for your 3 Hobbs hours. The FBO is basically stuck eating that maintenance expense.&lt;br&gt;&#xA;Along similar lines when renter pilots abuse an engine (for example by leaving the mixture knob full rich for the whole flight) the tach time doesn't always tell the whole maintenance story - the mechanic's time cleaning the plugs because the next renter couldn't get through a runup has to be paid for somehow.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-07T20:46:53.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11548" PostTypeId="1" AcceptedAnswerId="11549" CreationDate="2015-01-07T21:16:21.323" Score="8" ViewCount="666" Body="&lt;p&gt;After reading &lt;a href=&quot;https://aviation.stackexchange.com/a/11541/65&quot;&gt;this answer&lt;/a&gt; that a restricted airport caused a strange cutout in Class B, I am wondering if it possible that there are multiple airfields in the same airspace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, then:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Which ATC has most authority&lt;/li&gt;&#xA;&lt;li&gt;How congestion is handled?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Please note that I am not talking about an airport which is under an outer circular shelf of a Class B or C airport.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-07T23:55:13.537" Title="Can multiple airfields be in the same airspace?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11549" PostTypeId="2" ParentId="11548" CreationDate="2015-01-07T21:16:21.323" Score="7" Body="&lt;p&gt;When there are several airports close to each other, a single ATC, formally known as Terminal Control Center may service all airports. The airspace boundaries and altitudes assigned to a Terminal Control Center, which vary widely from airport to airport, are based on factors such as traffic flows, neighboring airports and terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/London_Terminal_Control_Centre&quot; rel=&quot;nofollow noreferrer&quot;&gt;London Terminal Control Centre&lt;/a&gt; is an example of a large and complex Terminal Control Center. Its service area is up to 20,000 feet and out to 100 nautical miles. It controls:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;six London airports&lt;/li&gt;&#xA;&lt;li&gt;one Royal Air Force station&lt;/li&gt;&#xA;&lt;li&gt;provides en-route services to other aircraft that entered its airspace&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Another example can be found with &lt;a href=&quot;http://skyvector.com/airport/EDDT/Berlin-Tegel-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Berlin-Tegel&lt;/a&gt; and &lt;a href=&quot;http://skyvector.com/airport/EDDB/Berlin-Schonefeld-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Berlin-Schönefeld&lt;/a&gt;, which have adjacent control zones that share a common boundary west to east and have an overlaying class C TMA airspace up to FL100. Both airports share the same TMA controller/approach sector:&lt;br&gt;&lt;code&gt;BREMEN RADAR Approach:    119.62&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZTPAc.png&quot; alt=&quot;CTR Area Berlin&quot;&gt;&lt;br&gt;&lt;sub&gt;&lt;em&gt;Image Source: www.skyvector.com&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;FAA is implementing a new airspace system which will increase efficiencies at metropolitan areas with complex air traffic flows. This system, known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Next_Generation_Air_Transportation_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Next Generation Air Transportation System&lt;/a&gt; is introducing the concept of a &lt;a href=&quot;https://www.faa.gov/nextgen/snapshots/metroplexes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;metroplex&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In FAA parlance, metroplex refers to a system of airports in close&#xA;  proximity and their shared airspace that serve one or more major&#xA;  cities. A metroplex has at least one, but often two or more major&#xA;  commercial airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="572" LastEditDate="2015-01-07T23:55:13.537" LastActivityDate="2015-01-07T23:55:13.537" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11550" PostTypeId="1" AcceptedAnswerId="11553" CreationDate="2015-01-08T01:43:28.517" Score="14" ViewCount="3938" Body="&lt;p&gt;When I was a young student pilot, long before the FAA prohibition on polished frost went into effect, an instructor left a six-inch square of frost on the wing to demonstrate how fast it would disappear after takeoff.  Sure enough, we hadn't even reached pattern altitude and the frost was completely gone.  Furthermore, in my experience frost never forms on an airplane as long as it's moving, or as long as there's sufficient airflow moving across it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never been able to find a satisfactory explanation for this.  &lt;strong&gt;Why doesn't frost form on a moving airplane?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2019-03-29T19:49:38.473" Title="Why doesn't frost form on a moving airplane?" Tags="&lt;weather&gt;&lt;cold-weather&gt;&lt;icing&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11551" PostTypeId="1" CreationDate="2015-01-08T04:46:52.000" Score="9" ViewCount="1635" Body="&lt;p&gt;Sometimes flames come out from the exhaust due to bearing distress or turbine blade fracture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can such flames/fire be considered an engine fire?&lt;/p&gt;&#xA;" OwnerUserId="6748" LastEditorUserId="64" LastEditDate="2015-01-08T19:43:24.090" LastActivityDate="2019-06-02T22:02:23.010" Title="Is an engine surge classed as an engine fire?" Tags="&lt;jet-engine&gt;&lt;terminology&gt;&lt;turbine&gt;&lt;fire&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11552" PostTypeId="2" ParentId="11551" CreationDate="2015-01-08T08:01:38.907" Score="9" Body="&lt;p&gt;If the fire is momentarily and stops by itself: &lt;strong&gt;No&lt;/strong&gt;, this is not an engine fire. Flames can come out of the engine at both ends in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/7799/why-do-jet-engines-sometimes-spit-out-flames-after-ingesting-birds?rq=1&quot;&gt;compressor stall&lt;/a&gt; (also called surge - watch the movie which is linked in the question!), but that is no engine fire. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/9116/why-does-the-f-111-sometimes-squirt-a-giant-fire-plume-behind-it-not-afterburn&quot;&gt;this question&lt;/a&gt; for another example where spectacular flames develop, yet the engine is not on fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the fire can only be stopped by shutting off the fuel supply or the engine itself: &lt;strong&gt;Yes&lt;/strong&gt;, that is an engine fire. I guess you refer in your question to &lt;a href=&quot;http://caa.gov.il/index.php?option=com_docman&amp;amp;view=download&amp;amp;category_slug=2013&amp;amp;alias=3067-ne-13-31&amp;amp;Itemid=669&amp;amp;lang=he&quot; rel=&quot;nofollow noreferrer&quot;&gt;this bulletin&lt;/a&gt; on PW4000s, where the No. 4 bearing overheated due to insufficient lubrication. In that case the oil itself overheated and burned, but this still makes it an engine fire.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="8282" LastEditDate="2019-06-02T22:02:23.010" LastActivityDate="2019-06-02T22:02:23.010" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="11553" PostTypeId="2" ParentId="11550" CreationDate="2015-01-08T09:37:31.383" Score="17" Body="&lt;p&gt;Frost can be formed in two ways. On a colder object by water directly desublimating on its surface or on any object when air is saturated with water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Frost &lt;strong&gt;can&lt;/strong&gt; form on a moving airplane, but only the &lt;em&gt;second way&lt;/em&gt;. Why would they have anti-ice on pitot tubes, propeller and leading edges otherwise?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the air is not saturated with water, ice will sublimate. If the air is moving it carries away the sublimated vapour and thus increases the sublimation rate. When flying in visual meteorological conditions, that's generally the case, so frost &lt;strong&gt;won't form in VMC,&lt;/strong&gt; thogh watch out when dew point is close to temperature; in such case light haze may form that already causes some icing while visibility is still above the VMC limit. Ram and friction heating also help sublimating the ice a bit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However when you fly into a cloud in freezing temperature, the water droplets will freeze on the aircraft when they hit it. They will hit it on forward-facing surfaces: wing and stabilizer leading edges, propellers, engine inlets, pitot tubes and nose and windscreen. That's why these components have anti-ice, either using heating or deicing boots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VMC-only aircraft will often only have pitot tube heating and carburettor heating, because those can sometimes gather frost in sufficiently moist air that is not yet forming cloud. This lack of anti-ice makes flying into IMC even more dangerous in winter than it already is for all the other reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Icing only happens when the cloud contains supercooled water droplets, which occurs in clouds where the ambient air temperature is between freezing point (0°C/32°F) and around -40°C/-40°F when the droplets freeze to ice pellets. The exact point the droplets freeze varies somewhat because it depends on other parameters like amount of dust, but pilots can check whether they are accreting any ice by looking in the corners of the windscreen. Whether freezing conditions are to be expected will also be mentioned in the detailed weather forecast.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-08-06T07:34:17.253" LastActivityDate="2015-08-06T07:34:17.253" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11555" PostTypeId="1" AcceptedAnswerId="11560" CreationDate="2015-01-08T12:06:58.193" Score="56" ViewCount="15189" Body="&lt;p&gt;A few days ago, I took a flight home. Towards the end of the journey, the captain asked us to shut down any electronic device that we had on board, including iPods, CD players, phones and so on, because there was very low visibility, and we were starting an instrument approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I could understand, an &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot;&gt;Instrument Landing  System (ILS)&lt;/a&gt; allows an aircraft to be centred on the approach path, assisted by radio signals delivered by an ILS (a localiser and a glide slope), without any visual reference. These signals are in the 110 MHz (LOC) and 330 MHz (GS) frequency range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that for the take off, visual landing, and the journey itself, shutting off the devices is no longer required (even though there are radio signals being used for communications and navigation), why this extra precaution on a low-visibility ILS approach? What interference could a CD Player possibly produce with the instrumentation to an extent that it's more dangerous than with the normal take off,en route, and landing phases?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note: as you probably understood, my level of expertise is very low, so forgive any dumb mistake or oversight.&lt;/p&gt;&#xA;" OwnerUserId="6752" LastEditorUserId="3504" LastEditDate="2015-01-09T17:56:57.490" LastActivityDate="2015-08-06T02:40:33.977" Title="Instrument landing: why do all electronic devices need to be shut off?" Tags="&lt;landing&gt;&lt;instrument-flight-rules&gt;&lt;electronics&gt;&lt;ils&gt;" AnswerCount="6" CommentCount="15" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11556" PostTypeId="2" ParentId="11555" CreationDate="2015-01-08T13:10:11.863" Score="19" Body="&lt;p&gt;You can read this &lt;a href=&quot;https://aviation.stackexchange.com/questions/2021/why-arent-cell-phones-allowed-to-be-used-in-aircraft&quot;&gt;related question&lt;/a&gt; if you want to learn more about the interference between electronic devices and airplanes. An answer there links to a very good &lt;a href=&quot;http://asrs.arc.nasa.gov/docs/rpsts/ped.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;document &lt;/a&gt; written by NASA on the topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long story short: Electronic devices are complicated. Airliners are complicated. Therefore, we can not predict exactly what the interference between them will be in all situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What your captain did happens frequently and is also covered in the relevant &lt;a href=&quot;http://www.faa.gov/about/initiatives/ped/faq/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA FAQ.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once your airline has shown the FAA its airplanes can safely handle&#xA;  radio interference from portable electronics, they can let you use&#xA;  your devices in airplane mode only most of the time. &lt;strong&gt;At certain times&#xA;  — for example, a landing in reduced visibility — the Captain may tell&#xA;  passengers to turn off their devices to make absolutely sure they&#xA;  don't interfere with onboard communications and navigation equipment.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, the reason is that the captain wants to be absolutely 100% sure that there will not be any interference during such a critical point.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-01-08T15:03:26.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11557" PostTypeId="2" ParentId="11536" CreationDate="2015-01-08T13:15:06.013" Score="3" Body="&lt;p&gt;Yes. As you specify it. This sounds perfectly correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get the technicalities straight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who is PF? When you do your departure briefing, you specify who is PF. I was trained to start departure briefing with &quot;I fly Piper Arrow, normal take-off. Maximum power, flaps 10, etc...&quot; and then going on the emergency part, &quot;...I will take all emergency actions, ...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who is PIC? This is answered by the column in which your enter the hours in your logbook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As PIC, you are in command of the aircraft. You fly it or decide to hand over the flying duties.&#xA;The instructor can do everything else, checklists, watch your airspeed/altitude etc. However having many more hours than you he is aware of how to fly &quot;an aircraft&quot; better than you. So he can clearly detect if you are not going to be able to finish the job and should (if he feels the need) say &quot;I have control&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, even if the instructor had experience of landing with a wheel not locked, he may consider it good experience for you to land it anyway - provided you discussed how you were going to do it (airspeed, attitude, rudder (nose wheel), ailerons etc.)&lt;/p&gt;&#xA;" OwnerUserId="6754" LastActivityDate="2015-01-08T13:15:06.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11559" PostTypeId="2" ParentId="11555" CreationDate="2015-01-08T15:31:31.710" Score="6" Body="&lt;p&gt;Because &lt;strong&gt;they don't want to take any chances&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although &lt;em&gt;most electronics&lt;/em&gt; have been shown to be unlikely to interfere with &lt;em&gt;most avionics/communications equipment&lt;/em&gt; in &lt;em&gt;most common circumstances&lt;/em&gt; the simple fact remains that we aren't totally sure yet. As RRR said, airliners and electronics are both very complex, and we can't predict exactly what will happen in every situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a visual landing with instrument assistance, a small error is unlikely to matter too much - if you're a little fast you may get a bumpy landing, or an incorrect descent rate may cause a bounce or a go-around etc, but the landing is unlikely to be off by a significant enough margin to cause a crash. If there's a small deviation in course/speed/altitude it won't matter, the pilot will simply correct it - likely without even noticing he's doing it - or nobody will notice/care. If there's a larger error the pilot will almost certainly notice (&quot;Wait, why is the runway over there?&quot;) and fix the problem&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an instrument landing, however, a very small margin of error in course/airspeed etc, present for 20 miles while the pilot has no frame of reference to know that it's wrong, can cause a major issue, because the cumulative error can add up over time and there's no way to know it's wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chances are, your phone will make absolutely no difference to the plane. But on that one occasion it does cause a problem, 300 people may be killed in a fireball. That makes &quot;asking you to stop playing Angry Birds for 30 minutes&quot; a very small price to pay for a a potential life-saving precaution.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-01-08T15:48:57.760" LastActivityDate="2015-01-08T15:48:57.760" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11560" PostTypeId="2" ParentId="11555" CreationDate="2015-01-08T15:41:41.467" Score="70" Body="&lt;p&gt;Short answer: ILS is rather sensitive to interference and not all electronic devices take much precaution in avoiding the generation of interference. The pilot wants to be sure that the readings he's getting on the localizer and glideslope are accurate, since he can't actually see the runway to verify the final approach path visually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: ILS is actually relatively simplistic as RF signals go. Both the localizer and the glideslope just consist of a pair of AM signals that are broadcast directionally. For both systems, the modulated frequencies are 90 Hz and 150 Hz. For the localizer, 90 Hz is broadcast to the left of the runway centerline and 150 Hz is broadcast to the right of the centerline. When the aircraft is aligned with the runway, it will receive equal strength signals of both frequencies. When it's to the right, it will receive more power from the 150 Hz signal and when it's to the left, it will receive more power from the 90 Hz signal. The glideslope works pretty much the same way, just with the 150 Hz signal transmitted below the glide path and the 90 Hz signal transmitted above it. &lt;a href=&quot;http://instrument.landingsystem.com/ils-ground-equipment/#localizer-transmitter&quot;&gt;[1]&lt;/a&gt; &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_21/glidescope_story.html&quot;&gt;[2]&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, suppose some passenger's electronic device is emitting a frequency that it shouldn't be. This is not exactly unheard of among consumer electronic devices. This is more common among devices manufactured in countries with less-strict emissions testing requirements/enforcement, but it's possible due to slight defects in almost any device. [Source: I design RF receivers for a living.] Now suppose that this noise happens to be on the localizer or glideslope frequency for the runway to which the aircraft is flying an approach. Hopefully you're starting to see a problem here... Whatever amplitude changes are happening on this unintended emission are now being received by the AM demodulator of the localizer or glideslope, potentially confusing it and, in low visibility conditions, causing the aircraft to be directed somewhere other than the runway threshold. &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot;&gt;Needless to say, that's bad.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_21/glidescope_story.html#3&quot;&gt;Boeing recommends the following actions for flight crews flying ILS approaches&lt;/a&gt; in order to detect erroneous ILS readings:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crosschecking altitude and DME distance periodically.&lt;/li&gt;&#xA;&lt;li&gt;Crosschecking altitude and flight management system (FMS) threshold distance.&lt;/li&gt;&#xA;&lt;li&gt;Crosschecking altitude and the crossing altitude of the outer marker (or locator, very-high-frequency omnirange [VOR] navigation equipment, or FMS).&lt;/li&gt;&#xA;&lt;li&gt;Crosschecking radio altitude and barometric altitude.&lt;/li&gt;&#xA;&lt;li&gt;Crosschecking ground speed and rate of descent.&lt;/li&gt;&#xA;&lt;li&gt;Questioning air traffic controllers when indications do not appear to be correct.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, even when following those instructions, slightly erroneous ILS signals may be hard to detect until too late. If a DME is showing that you're half a mile off, you can probably notice that, but a couple hundred feet off might not be noticeable (but is still plenty to be a big problem.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-01-08T15:48:00.400" LastActivityDate="2015-01-08T15:48:00.400" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11561" PostTypeId="1" AcceptedAnswerId="11562" CreationDate="2015-01-08T16:23:28.360" Score="3" ViewCount="647" Body="&lt;p&gt;I was wondering why some airfields, for example &lt;a href=&quot;http://en.wikipedia.org/wiki/Tatenhill_Airfield&quot; rel=&quot;nofollow&quot;&gt;Tatenhill Airfield (EGBM)&lt;/a&gt;, don't have anybody in their ATC towers?&lt;/p&gt;&#xA;" OwnerUserId="6757" LastEditorUserId="65" LastEditDate="2015-01-08T17:30:08.610" LastActivityDate="2015-01-08T21:16:02.500" Title="Why do some airfields not have manned ATC towers?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11562" PostTypeId="2" ParentId="11561" CreationDate="2015-01-08T16:34:54.820" Score="2" Body="&lt;p&gt;In the case of Tatenhill, the field was previously used by the RAF. Evidently the original control tower was &lt;a href=&quot;http://www.watsonlv.net/tatenhill.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;replaced by a previous operator&lt;/a&gt;, which explains why there is still a control tower there. But currently it is a private field, where the amount of traffic doesn't warrant operating the control tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&amp;amp;task=blogcategory&amp;amp;id=143&amp;amp;Itemid=192.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Information from NATS&lt;/a&gt; lists a Tatenhill Radio frequency that provides A/G (air to ground) service during certain hours. &lt;a href=&quot;https://www.youtube.com/watch?v=p09cog4El8M&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube videos&lt;/a&gt; suggest &lt;a href=&quot;https://www.youtube.com/watch?v=Avczho9zP0g&quot; rel=&quot;nofollow noreferrer&quot;&gt;no tower services&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many airports in similar situations, that do not operate a control tower (whether or not they have one), or only operate at certain times, when there is not enough traffic for a control tower to be needed. VFR rules give pilots the responsibility to &quot;see and avoid&quot; each other in these areas, and announce their intentions on the appropriate frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see the related questions to the right, especially: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1218/whats-the-process-for-an-uncontrolled-airfield-to-become-controlled-towered?rq=1&quot;&gt;What&amp;#39;s the process for an uncontrolled airfield to become controlled/towered?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-08T16:58:06.610" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11563" PostTypeId="1" AcceptedAnswerId="11564" CreationDate="2015-01-08T19:05:10.243" Score="9" ViewCount="1986" Body="&lt;p&gt;Since the A350 is one of the most efficient jets out there, Is it possible that it can be transformed into a fuel tanker for Aerial refuelling?&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="572" LastEditDate="2015-02-25T07:29:45.813" LastActivityDate="2015-02-25T07:29:45.813" Title="Could the Airbus A350 be converted into the role of air tanker / be used for aerial refuelling?" Tags="&lt;fuel&gt;&lt;airbus&gt;&lt;fuel-tanks&gt;&lt;airbus-a350&gt;&lt;refueling&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11564" PostTypeId="2" ParentId="11563" CreationDate="2015-01-08T19:32:46.383" Score="9" Body="&lt;p&gt;Yes, it could be done. There is an &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A330_MRTT&quot; rel=&quot;noreferrer&quot;&gt;A330 already working&lt;/a&gt; as fuel tanker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wz66b.jpg&quot; alt=&quot;A330 MTT&quot;&gt;&#xA;&lt;sub&gt;&lt;em&gt;Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A330_MRTT#Operational_history&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus might build a A350 air re-fueler &lt;a href=&quot;http://formerspook.blogspot.com/2006/03/turbulence-ahead-for-airbus.html&quot; rel=&quot;noreferrer&quot;&gt;as mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus is already offering a tanker version of the A330, and could&#xA;  (potentially) upgrade their proposal with an A350 air-refueler. The&#xA;  A350 would offer a substantial increase in fuel offload from existing&#xA;  tankers, as well as the 767.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-01-08T19:32:46.383" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11565" PostTypeId="2" ParentId="11561" CreationDate="2015-01-08T19:52:18.713" Score="4" Body="&lt;p&gt;One of the biggest reasons to not man a tower is (not unsurprisingly) costs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many remote airports only have a few movements per day, and a permanent staff in the tower makes it even more difficult keep the operation economically viable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason, remotely staffed towers are being developed now, and for instance &lt;a href=&quot;http://en.wikipedia.org/wiki/%C3%96rnsk%C3%B6ldsvik_Airport&quot; rel=&quot;nofollow&quot;&gt;Örnsköldsvik airport (ESNO)&lt;/a&gt; in Sweden has &lt;a href=&quot;http://www.ainonline.com/aviation-news/2014-11-04/swedish-transport-agency-oks-saab-remote-tower-ornskoldsvik-airport&quot; rel=&quot;nofollow&quot;&gt;just received approval&lt;/a&gt; from the Swedish Transport Agency to operate with a remote tower:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The system’s sensors are installed at Ornskoldsvik Airport but traffic&#xA;  is remotely controlled from Sundsvall, Sweden.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="65" LastEditDate="2015-01-08T21:16:02.500" LastActivityDate="2015-01-08T21:16:02.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11566" PostTypeId="2" ParentId="11563" CreationDate="2015-01-08T20:46:14.687" Score="8" Body="&lt;p&gt;While payload, range, and efficiency are important for tankers, militaries have reasons for still using so many 707 variants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the reasons are similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11332/why-does-the-us-president-fly-in-an-obsolete-747-200&quot;&gt;Why does the US President fly in an obsolete 747-200?&lt;/a&gt; Although making an aircraft into a tanker may be less challenging than making it into a &lt;a href=&quot;http://en.wikipedia.org/wiki/VC-137C_SAM_26000&quot; rel=&quot;nofollow noreferrer&quot;&gt;SAM&lt;/a&gt; aircraft, it is still a large task. The fuel system needs to be modified and significantly extended, and many other components will be upgraded to military standards. This is a large investment for what is a relatively small fleet of aircraft. It has been more economical to &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_KC-135_Stratotanker#Variants&quot; rel=&quot;nofollow noreferrer&quot;&gt;upgrade the aircraft&lt;/a&gt; rather than select newer models. Smaller fleets of tankers have been converted from existing aircraft, which is cheaper with older designs rather than the latest and greatest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, like the SAM aircraft, &lt;a href=&quot;https://www.fas.org/irp/agency/dod/dsb/aerial.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;tankers do not see nearly as much flight time&lt;/a&gt; as commercial aircraft. The KC-135 fleet stood at an average of 17,000 hours in 2004, with a fatigue life of about 36,000 hours. This means that gains in efficiency are less important, and other costs like maintenance and acquisition are more important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have only been orders for about 50 A330 MRTT aircraft. Boeing built 8 KC-767 airplanes, and there are only 3 orders for tanker conversions. The US Air Force is ordering 179 of the KC-46 tankers, with possible further export sales. This overall represents a fairly small market.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important requirement is service life. The KC-135 aircraft in the US Air Force have been in service for at least 50 years now. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Vickers_VC10&quot; rel=&quot;nofollow noreferrer&quot;&gt;RAF&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_TriStar_%28RAF%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft&lt;/a&gt; are conversions and had a long service life, but not as long as the KC-135. The 767 and A330 aircraft currently being introduced as tankers are newer designs, but still with a long and proven service history. The A350 represents a large step in aircraft design, using composites much more extensively than before. While there is certainly a good amount of confidence that these aircraft will have a long service life, militaries may want to wait until the new design concepts have proven themselves before making expensive orders.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-01-08T20:46:14.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11567" PostTypeId="1" CreationDate="2015-01-08T23:45:10.010" Score="12" ViewCount="9945" Body="&lt;p&gt;I would like to take my friend and his dog for a flight. What's the safest way to take the dog? and what's a good way to protect the dog's hearing?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2020-04-28T17:38:31.317" Title="What's the right way to take a dog in a small plane?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;passenger&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11568" PostTypeId="1" CreationDate="2015-01-09T00:59:29.707" Score="6" ViewCount="6984" Body="&lt;p&gt;I know I should update the database in my GPS, but nevertheless I'm wondering if i can use an expired IFR-certified GPS with an out-of-date database in lieu of DME&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2018-07-02T20:14:25.337" Title="Can I use an expired IFR-certified GPS with an out of date database in lieu of DME?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;gnss&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11569" PostTypeId="2" ParentId="11568" CreationDate="2015-01-09T03:07:11.553" Score="10" Body="&lt;p&gt;The answer would appear to be &quot;Maybe&quot;, &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html&quot;&gt;per the AIM (table 1-1-6)&lt;/a&gt;: You are permitted to use an IFR-approved GPS &quot;In Lieu of ADF and/or DME&quot;, however the footnote (3) to that table tells us that this use&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Requires current database or verification that the procedure has not been amended since the expiration of the database.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you're using the GPS to calculate something like &quot;5 Miles DME from JFK VOR&quot; that would seem to be acceptable (the FAA is unlikely to pick up JFK VOR and move it without making a lot of noise about it), &lt;em&gt;but&lt;/em&gt; if you're using by punching in a fix that's defined by DME and a radial you would need to somehow verify that the fix hadn't been redefined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can accomplish that verification in a number of ways (a current IFR chart on your iPad or a current paper chart seem like obvious ways). As long as you can satisfy yourself (and the FAA) that the data in the GPS is accurate the operation would appear to be permissible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also appear that if you verify that the fix has been redefined (say FUBAR was 5 DME, now it's 6 DME) you could still use the GPS &lt;em&gt;distance&lt;/em&gt; data in lieu of DME, just not the incorrectly-programmed fix. That is, you could determine when you're 6 miles DME from JFK VOR, and since you know the FAA didn't move the VOR and that the fix is now at 6 miles you now you're where you want to be.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-09T03:07:11.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11570" PostTypeId="2" ParentId="11567" CreationDate="2015-01-09T04:17:37.683" Score="4" Body="&lt;p&gt;My wife and I have a small dog that frequently travels with us.  We place her in a soft-sided kennel that straps onto the seat belt.  While this doesn't do anything to help in a sudden impact (i.e. crash), it does help to keep her from being bumped around in case of turbulence.  For larger dogs, I know that there are seat belt tethers out there.  My suggestion would be to strap them to a rear seat.  In either case, the big issue is to ensure they don't get in the way while operating the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the hearing part, a company called &lt;em&gt;Safe and Sound Pets&lt;/em&gt; makes a product called &lt;strong&gt;Mutt Muffs&lt;/strong&gt;.  Their website is &lt;a href=&quot;http://www.safeandsoundpets.com/index.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.  My wife and I bought a pair, but our dog wouldn't have anything to do with them and they were returned.  Of course, your dog may be better behaved :D&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-01-09T04:17:37.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11571" PostTypeId="2" ParentId="11567" CreationDate="2015-01-09T04:18:09.350" Score="0" Body="&lt;p&gt;My dog flies with his &lt;a href=&quot;http://www.safeandsoundpets.com/index.html&quot; rel=&quot;nofollow&quot;&gt;Mutt Muffs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a pinch, you can also put cotton balls in a dogs ears.  Carefully put them in enough that he cannot paw them out, but not so far as to get into the sensitive parts.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-01-09T04:18:09.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11572" PostTypeId="2" ParentId="11551" CreationDate="2015-01-09T04:34:28.867" Score="6" Body="&lt;p&gt;Engine surge or stall occurs when there is a breakdown in smooth flow of air through the jet engine compressor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be caused by incorrect airflow control within the engine itself by faulty scheduling of  Inlet Guide Vanes (IGVs) within the compressor or overfueling during acceleration due to faults within airfuel control. Ice ingestion or heavy bird ingestion may damage the compressor by disrupting airflow and creating a surge in extreme cases. Surges may be recognised as burbling or popping in mild cases with airflow disruption within one or a couple of compressor stages only, or large explosive bang in extreme cases of compressor or turbine damage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surges in flight may occur at altitudes depending on throttle handling and type / generation / condition / cleanliness of the compressor or airplane involved. Fire breakout is not the normal consequence of an engine surge unless there is severe damage by failure of a rotating part at high power. Perfection of design, materials and computerized engine control has reduced surge events dramatically over last 15 years or so.&lt;/p&gt;&#xA;" OwnerUserId="6761" LastEditorUserId="19" LastEditDate="2015-01-09T09:25:15.900" LastActivityDate="2015-01-09T09:25:15.900" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11573" PostTypeId="2" ParentId="8715" CreationDate="2015-01-09T05:00:27.100" Score="0" Body="&lt;p&gt;Yes, and in the short-term they're also talking about re-engining the existing A380 with engines based on those on the A320neo &lt;a href=&quot;http://www.ausbt.com.au/airbus-confirms-a380neo-and-a380-stretch&quot; rel=&quot;nofollow&quot; title=&quot;Airbus CEO: we will launch A380neo and A380 &amp;#39;stretch&amp;#39;&quot;&gt;as outlined here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3846" LastActivityDate="2015-01-09T05:00:27.100" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11575" PostTypeId="1" AcceptedAnswerId="11578" CreationDate="2015-01-09T05:52:50.057" Score="8" ViewCount="13248" Body="&lt;p&gt;Is there some data available which shows the intervals at which planes take off and land at Chicago O'Hare?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just by taking a look around the last time I visited ORD couple of months back, it seems to be one almost every 10-15 secs.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="14897" LastEditDate="2018-03-21T23:12:37.287" LastActivityDate="2018-04-18T16:54:56.250" Title="At what intervals do planes land and take off from Chicago O'Hare?" Tags="&lt;airspace&gt;&lt;air-traffic-management&gt;&lt;airport-capacity&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11577" PostTypeId="2" ParentId="11489" CreationDate="2015-01-09T05:59:44.733" Score="11" Body="&lt;p&gt;They're also extraordinarily harrowing. If you ever do read the transcripts, try and imagine them taking place between two or more pilots trying to deal with a deadly situation for themselves and their passengers. While accompanied by the background noise of violent maneuvering, alarms or engines screaming or indeed engines on fire or exploding. Or in really bad cases, hijackers yelling commands. Or if things are really bad, all of the above. And then often finishing with the sound of a plane impacting the ground, cutting off suddenly and being replaced by an ominous silence. I personally would not want to hear such a recording.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen a transcript which ends with one of the pilots yelling &quot;I love you mom!&quot; just before their plane hits the ground, killing everyone on board...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally on a more practical note, pilots use a lot of jargon and abbreviations, some of which is specific to the model of aircraft being flown. If you don't know what a flight level is, or what ATC or approach are, or which check-list they're talking about, then they can sound and read like gibberish. And that's assuming they're speaking English. Flight crews talk in their native tongues whilst flying and not talking on the radio. So for example a recording from an Air France flight would be largely in French.&lt;/p&gt;&#xA;" OwnerUserId="3846" LastActivityDate="2015-01-09T05:59:44.733" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11578" PostTypeId="2" ParentId="11575" CreationDate="2015-01-09T08:02:09.843" Score="9" Body="&lt;p&gt;As a general average, Chicago O'Hare (KORD) seems to do somewhere between 1.5 and 2 operations per minute (so roughly one takeoff or landing every 30-40 seconds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I based this on data from the FAA's &lt;a href=&quot;https://aspm.faa.gov/opsnet/sys/Terminal.asp&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Activity Data System - Terminal Operations&lt;/a&gt; report, and specifically looked at November 23 through November 30 of 2014 (17835 operations, over 8 days works out to 1.55 operations per minute - I poked around randomly and found days as high as 1.7 operations per minute).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the limiting factors for number of operations at any airport is separation between aircraft, which is covered &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/ATpubs/ATC/atc0309.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Incidentally we were discussing airport/tower activity levels &lt;a href=&quot;http://chat.stackexchange.com/rooms/12036/conversation/airport-activity-discussion-for-q-11575&quot;&gt;in chat&lt;/a&gt; earlier today, and Chicago O'Hare is the busiest airport in the United States overall - a title it recently stole back from ATL (which was #1 from 2004 to 2013).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2015-01-09T17:54:18.577" LastActivityDate="2015-01-09T17:54:18.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11579" PostTypeId="2" ParentId="9526" CreationDate="2015-01-09T08:07:32.980" Score="0" Body="&lt;p&gt;Of more importance to the pilot in monitoring engine performance is the Engine Pressure Ratio (EPR) gauge.EPR is a ratio of compressor inlet pressure against exhaust pressure which shows the efficiency of the propulsion process front to back.  EPR is measured in percentages, 100% being maximum thrust required to take off safely at a given aircraft weight, runway length and under prevailing weather conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of secondary concern to the pilot is the Turbine Gas Temperature (TGT) sometimes  termed Exhaust Gas Temperature (EGT) or Turbine Inlet Temperature (TIT). Higher life engines will exhibit higher TGT up to a maximum safe limit for turbine blade life. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also of interest is the performance at a given fuel flow as measured on the fuel flow meter. RPM monitoring is of relatively insignificant performance provided max speeds are not exceeded during take off power. A high life almost worn out engine will not be able to produce its required take off EPR on a hot day, fully loaded aircraft on short runway without exceeding either TGT or RPM max limits. However, the same engine may produce sufficient EPR on a cold day, light loaded aircraft on a long runway. Pilots of 1970,s generation engines had to refer to charts when selecting &quot;TAKE OFF EPR OF THE DAY&quot;.  Modern FADEC engine controls make all the calculations and adjustments automatically.&lt;/p&gt;&#xA;" OwnerUserId="6761" LastEditorUserId="19" LastEditDate="2015-01-09T09:56:14.233" LastActivityDate="2015-01-09T09:56:14.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11580" PostTypeId="2" ParentId="9144" CreationDate="2015-01-09T08:30:16.257" Score="1" Body="&lt;p&gt;A new or overhauled engine's thrust on a manufacturer's test bed is measured against a load cell or thrust meter at given RPM, TGT (Turbine Gas Temperature),fuel flow and EPR (Engine Pressure Ratio). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the certified engine is installed in the airframe and ground run, after taking into account local atmospheric conditions,intake and jet pipe losses, the maximum EPR, or thrust, and TGT and fuel flows can be cross checked. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a test flight, given the correction factors for altitude and speed etc, against the known parameters of EPR, TGT, RPM and fuel flow, the engine can be seen to be giving required performance. If the the engine parameters are correct but aircraft performance (i.e. speed and rate of climb) are low then suspect the airplane's weight and/or drag (flap, doors, panels etc poor fit) as possible culprits. Its not fair to expect an engine to push a dirty heavy airplane up that big hill on a hot day is it?&lt;/p&gt;&#xA;" OwnerUserId="6761" LastEditorUserId="19" LastEditDate="2015-01-09T12:22:10.937" LastActivityDate="2015-01-09T12:22:10.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11582" PostTypeId="1" AcceptedAnswerId="11583" CreationDate="2015-01-09T10:16:49.143" Score="53" ViewCount="27857" Body="&lt;p&gt;I know twin-engine jets can safely take off and fly with one engine out (i.e. all thrust only on one side).  Of course quad-engine jets are also able to fly safely in case one engine is out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But is the A380 designed to also fly safely in case &lt;strong&gt;two&lt;/strong&gt; engines &lt;em&gt;on the same wing&lt;/em&gt; are out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would the rudder be able to compensate the thrust imbalance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm referring to an engine-out situation in flight, not during take off.  I would assume that the problems aggravate during take off since the rudder has less airflow to counter the imbalance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Two engines out on the same wing is not a very likely scenario, but it's not impossible.  For example, on &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_32&quot;&gt;Qantas 32&lt;/a&gt;, damage from the number 2 engine explosion impacted fuel and control lines of engine 1.&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorUserId="69" LastEditDate="2015-04-18T23:38:30.330" LastActivityDate="2020-05-18T10:08:30.930" Title="Can the Airbus A380 safely fly with two engines out on the same wing?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;engine-failure&gt;&lt;aircraft-certification&gt;&lt;airbus-a380&gt;" AnswerCount="2" CommentCount="12" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11583" PostTypeId="2" ParentId="11582" CreationDate="2015-01-09T11:30:07.800" Score="73" Body="&lt;p&gt;Proving that a multi-engine aircraft is flyable with one or more engines inoperative is part of the certification programme. The Airbus A380 is certified under FAR (Federal Aviation Regulations, USA) part 25 and JAR (Joint Aviation Regulations, Europe) part 25. One of the requirements of FAR/JAR 25 is that the directional control can be maintained when two critical engines (that means under the same wing) fail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following is selectively extracted from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr25_main_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR part 25&lt;/a&gt; (JAR is similar, there are some differences). Emphasis added by me.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Controllability and Maneuverability&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§25.143   General.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;....&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b&lt;/strong&gt;) It must be possible to make a smooth transition from one flight&#xA;  condition to any other flight condition without exceptional piloting&#xA;  skill, alertness, or strength, and without danger of exceeding the&#xA;  airplane limit-load factor under any probable operating conditions,&#xA;  including—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The sudden failure of the critical engine;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;For &lt;strong&gt;airplanes with three or more engines&lt;/strong&gt;, the sudden &lt;strong&gt;failure of&#xA;  the second critical engine&lt;/strong&gt; when the airplane is in the en route,&#xA;  approach, or landing configuration and is trimmed with the critical&#xA;  engine inoperative;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$ $&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§25.147   Directional and lateral control.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a&lt;/strong&gt;)  Directional control; general. It must be possible, with the wings&#xA;  level, to yaw into the operative engine and to safely make a&#xA;  reasonably sudden change in heading of up to 15 degrees in the&#xA;  direction of the critical inoperative engine. This must be shown at&#xA;  1.3 V&lt;sub&gt;SR1&lt;/sub&gt; for heading changes up to 15 degrees (except that the heading change at which the rudder pedal force is 150 pounds need not be&#xA;  exceeded), and with—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The critical engine inoperative and its propeller in the minimum&#xA;  drag position;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The power required for level flight at 1.3 V&lt;sub&gt;SR1&lt;/sub&gt;, but not more than&#xA;  maximum continuous power;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The most unfavorable center of gravity;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Landing gear retracted;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Flaps in the approach position; and&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Maximum landing weight.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b&lt;/strong&gt;) Directional control; airplanes with &lt;strong&gt;four or more engines&lt;/strong&gt;.&#xA;  Airplanes with four or more engines must meet the requirements of&#xA;  paragraph (a) of this section except that—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The &lt;strong&gt;two critical engines must be inoperative&lt;/strong&gt; with their propellers&#xA;  (if applicable) in the minimum drag position;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;[Reserved]&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flaps must be in the most favorable climb position.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;c&lt;/strong&gt;) ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;d&lt;/strong&gt;) ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;e&lt;/strong&gt;) Lateral control; &lt;strong&gt;airplanes with four or more engines&lt;/strong&gt;. Airplanes&#xA;  with four or more engines must be able to make 20° banked turns, with&#xA;  and against the inoperative engine&lt;strong&gt;s&lt;/strong&gt;, from steady flight at a speed&#xA;  equal to 1.3 VSR1, with maximum continuous power, and with the&#xA;  airplane in the configuration prescribed by paragraph (b) of this&#xA;  section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;f&lt;/strong&gt;) ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$ $&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§25.149   Minimum control speed.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;g&lt;/strong&gt;) For airplanes with three or more engines, V&lt;sub&gt;MCL-2&lt;/sub&gt;, the minimum control speed during approach and landing with one critical engine&#xA;  inoperative, is the calibrated airspeed at which, when a second&#xA;  critical engine is suddenly made inoperative, it is possible to&#xA;  maintain control of the airplane with both engines still inoperative,&#xA;  and maintain straight flight with an angle of bank of not more than 5&#xA;  degrees. V&lt;sub&gt;MCL-2&lt;/sub&gt; must be established with—&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$ $&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§25.161   Trim.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;e&lt;/strong&gt;) Airplanes with four or more engines. Each airplane with four or&#xA;  more engines must also maintain trim in rectilinear flight with the&#xA;  most unfavorable center of gravity and at the climb speed,&#xA;  configuration, and power required by §25.123(a) for the purpose of&#xA;  establishing the en route flight paths with two engines inoperative.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="24744" LastEditDate="2020-05-18T10:08:30.930" LastActivityDate="2020-05-18T10:08:30.930" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="11584" PostTypeId="1" CreationDate="2015-01-09T14:03:01.480" Score="3" ViewCount="1638" Body="&lt;p&gt;If an engine fails in a passenger airplane, why can't it have movable rocket thrusters in the wings to help safely land the airplane?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="62" LastEditDate="2016-11-28T16:03:20.653" LastActivityDate="2019-12-18T00:19:06.100" Title="Why are movable rocket thrusters not used in airplanes?" Tags="&lt;aircraft-design&gt;&lt;engine-failure&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11585" PostTypeId="2" ParentId="11567" CreationDate="2015-01-09T16:23:44.950" Score="3" Body="&lt;p&gt;When you are flying with pets, there are certain things you need to consider which aren't normally considered when flying with people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the size and weight of a pet, a suitable carrier in which they can fit in is needed. You also need to make sure that this carrier must be able to fit in the plane and be secured. If the pet is large and cannot fit in carrier which can in the plane, a pet harness that can be secured to seat belts or seat belt attachment points can also be considered. It should be an approved car safety transport harness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some general guidelines are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pet should be secured.&lt;/li&gt;&#xA;&lt;li&gt;Allow the animals to relieve themselves before being loaded.&lt;/li&gt;&#xA;&lt;li&gt;As soon as the trip is complete provide water and some nutrition for the animals.&lt;/li&gt;&#xA;&lt;li&gt;It is very important to always clear the seats and plane after the journey. Dogs are very susceptible to &lt;a href=&quot;http://en.wikipedia.org/wiki/Parvovirus&quot; rel=&quot;nofollow noreferrer&quot;&gt;parvovirus&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Animals do not know that swallowing and yawning will help their ears in altitude changes like the humans. Hence, it is better the minimize the rate of climbs and descents to minimize discomfort to animals.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;AOPA has an &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Flying-With-Family/AOPA-Online-Members-Only-Aviation-Subject-Report-Traveling-With-Children-and-Family-Flying-With-Pets&quot; rel=&quot;nofollow noreferrer&quot;&gt;excellent and detailed article&lt;/a&gt; about flying with pets. For the hearing issue, they state:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... [by putting cotton in ears, it can] stuck in the wax of the ears&#xA;  and cause problems. The better option is to use pillow foam instead of&#xA;  cotton. Pillow foam is similar to what earplugs are made out of and is&#xA;  not as likely to get stuck in the ears.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I hope that your journey won't go like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5W8UM.jpg&quot; alt=&quot;dog in driver&amp;#39;s seat&quot;&gt;&#xA;&lt;br/&gt;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://santamonica.petsitpros.com/blog/&quot; rel=&quot;nofollow noreferrer&quot;&gt;image source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-01-09T16:23:44.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11586" PostTypeId="1" AcceptedAnswerId="11587" CreationDate="2015-01-09T16:24:22.677" Score="13" ViewCount="5885" Body="&lt;p&gt;According to the article &lt;a href=&quot;http://www.nytimes.com/2015/01/09/business/bombardiers-cseries-gamble-is-facing-longer-odds.html&quot;&gt;Bombardier’s CSeries Gamble Is Facing Longer Odds&lt;/a&gt;, this new plane from Bombardier uses a new engine technology that will improve efficiency over its rival 737 series and A320 series airplanes, to the point where it will be able to complete on a seat-mile efficiency basis with larger airplanes, enabling it to bypass hubs: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The linchpin for the CSeries was a new concept for engines developed&#xA;  by Pratt &amp;amp; Whitney, known as a high bypass geared turbofan. The new&#xA;  engine design promised exceptional fuel savings of up to 20 percent&#xA;  and unusually low noise levels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What's the theory behind this new engine, and what are the underlying numbers that make it competitive with larger airplanes?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="19" LastEditDate="2015-01-10T00:09:19.230" LastActivityDate="2015-01-10T00:09:19.230" Title="What is a &quot;high-bypass geared turbofan,&quot; and why is it so much more efficient?" Tags="&lt;airline-operations&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;&lt;turbine&gt;&lt;bombardier&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11587" PostTypeId="2" ParentId="11586" CreationDate="2015-01-09T17:56:08.780" Score="13" Body="&lt;p&gt;The fan section of a turbofan engine is driven by the low pressure (LP) spool. This means that it is connected to two parts of the engine:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The LP compressor, which must compress the air before it enters the high pressure (HP) compressor&lt;/li&gt;&#xA;&lt;li&gt;The LP turbine, which must receive the air after it exits the HP turbine&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The problem is that the HP section is efficient at high RPM. But the fan will reach aerodynamic limits as the fan tips pass supersonic speed. Fan blades are also harder to contain in the event of a failure as they spin faster. So to accommodate the fan, the LP section has to spin at a slower speed, which makes it harder to match with the high RPM HP section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a limitation on air flow. The fan must be able to move a maximum amount of air, which is takeoff power at sea level. But it must also be able to function efficiently at cruise level, where the flow is faster but much less dense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine companies use different strategies to deal with these limitations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GE mainly makes the LP sections larger in diameter. This allows the blades to have a high velocity at lower RPM. This this requires the air flow to change direction more rapidly.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/LZJ59.jpg&quot; alt=&quot;GE90 design&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls Royce has created a 3 spool design, which allows each section to spin at a more optimal RPM. This adds complexity to the design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SyBgu.png&quot; alt=&quot;Rolls Royce 3-spool engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pratt and Whitney is going with the geared fan approach. Similar to turboprops, there is a gearbox to allow the fan to spin at a lower speed than the engine spool that is driving it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MHoRM.jpg&quot; alt=&quot;PW geared design&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows the turbine spool to operate at a more optimal RPM while still allowing the fan to spin more slowly. A slower fan can be larger, allowing for a higher bypass ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high bypass ratio allows a turbofan engine to drive more air (produce more thrust) for less air going through the core (burn less fuel). Modern large aircraft have engines like the &lt;a href=&quot;http://www.geaviation.com/press/ge90/ge90_19951109a.html&quot; rel=&quot;noreferrer&quot;&gt;GE90&lt;/a&gt; on the 777 (9:1 bypass), with the latest engines on the 787 going even higher with the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;noreferrer&quot;&gt;GEnx&lt;/a&gt; (9.6:1 bypass), and &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot; rel=&quot;noreferrer&quot;&gt;Trent 1000&lt;/a&gt; (10.8:1). Smaller aircraft like the 737 and A320 currently use engines like the &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;noreferrer&quot;&gt;CFM56&lt;/a&gt; (5.5:1), with the new &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_LEAP&quot; rel=&quot;noreferrer&quot;&gt;LEAP&lt;/a&gt; going higher (9:1 or 11:1). The PW1000G goes even higher (up to 12:1).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-09T19:10:23.577" LastActivityDate="2015-01-09T19:10:23.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11589" PostTypeId="2" ParentId="11584" CreationDate="2015-01-09T20:10:09.750" Score="29" Body="&lt;p&gt;&lt;strong&gt;&lt;em&gt;Any&lt;/em&gt;&lt;/strong&gt; time the question is &lt;em&gt;&quot;why don't we have...&quot;&lt;/em&gt;, the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, &amp;amp; utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting rocket thrusters on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board.   All that extra weight has to be flown around, requiring fuel.  They would need regular maintenance checks, which is another cost.   And they would only be useful very, very infrequently (on most planes... never).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, safety issues completely aside*, it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This same line of reasoning goes for &lt;a href=&quot;https://aviation.stackexchange.com/questions/2186/why-are-commercial-flights-not-equipped-with-parachutes&quot;&gt;&lt;em&gt;&quot;why don't more airplanes have parachutes&quot;&lt;/em&gt;&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/7768/why-dont-airliners-carry-radar-jamming-technology-or-missile-counter-measures&quot;&gt;&lt;em&gt;&quot;why don't planes have anti-missile systems&quot;&lt;/em&gt;&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9818/airbags-in-aircraft-is-that-just-a-military-thing&quot;&gt;&lt;em&gt;&quot;why don't planes have airbags&quot;&lt;/em&gt;&lt;/a&gt;, and many other random items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;*Safety issues are a big deal with rockets.  Rockets are a &lt;em&gt;controlled explosion&lt;/em&gt;.  What happens if that explosion is not controlled?  What happens if the rockets are triggered by accident, or blow up all at once?  Even if rockets passed all the tests of utility vs. costs, they would still increase risks to the plane, rather than decreasing it.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-11-28T15:58:25.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11590" PostTypeId="2" ParentId="11584" CreationDate="2015-01-09T20:23:07.150" Score="9" Body="&lt;p&gt;&quot;Movable rocket thrusters,&quot; regardless of propulsion, are used for &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;noreferrer&quot;&gt;thrust vectoring&lt;/a&gt;&lt;/em&gt;, AKA &lt;em&gt;maneuvering&lt;/em&gt;, not forward motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're talking about something like an emergency &lt;a href=&quot;http://en.wikipedia.org/wiki/JATO&quot; rel=&quot;noreferrer&quot;&gt;JATO&lt;/a&gt; rocket, then the reason is because very, very few accidents happen strictly because of engine failure. Most engine failures (notwithstanding &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;US Airways Flight 1549&lt;/a&gt;) happen at an altitude where the plane can pick a safe landing spot, and glide to the runway.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-09T20:28:53.500" LastActivityDate="2015-01-09T20:28:53.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11591" PostTypeId="1" CreationDate="2015-01-09T21:15:51.527" Score="15" ViewCount="2573" Body="&lt;p&gt;I am a new pilot who flies out of an uncontrolled field. When I depart and want to ask the controller for the nearby controlled airfield for flight following, should I contact approach or departure, or it does not matter?&lt;/p&gt;&#xA;" OwnerUserId="6777" LastEditorUserId="19" LastEditDate="2015-01-10T00:06:42.547" LastActivityDate="2020-12-01T02:02:19.923" Title="Flying out from an uncontrolled field, should I contact approach or departure at the nearby control field?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11592" PostTypeId="2" ParentId="11591" CreationDate="2015-01-09T21:21:57.883" Score="11" Body="&lt;p&gt;&lt;em&gt;Approach&lt;/em&gt; and &lt;em&gt;departure&lt;/em&gt; are two facets of the same facility, the &lt;em&gt;TRACON&lt;/em&gt;, and it doesn't matter which you call, unless you're an IFR aircraft on an active flight plan or you have a flight plan on file that you want to activate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For flight following, more important than picking between approach and departure frequencies, is to contact the TRACON on the frequency for the airspace that overlies your position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, at &lt;a href=&quot;http://www.airnav.com/airport/KCVH&quot; rel=&quot;noreferrer&quot;&gt;Hollister&lt;/a&gt;, the TRACON is called &quot;Norcal,&quot; and it handles dozens of different sectors, each with its own frequency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/stMDZ.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frequency for approach and departure at Hollister are identical because that frequency is the arrivals frequency for San Jose International Airport (SJC). That's because Hollister is underneath the approach path for SJC, and that's whose radar screen you will pop up on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/e8wQM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you should do is look up the frequency for your airport (or for a nearby airport) in the A/FD, in Airnav.com, or in your GPS database, and use that. If it has a discrete departure frequency, then you should probably use that, even though its for IFR departures, but for VFR, it doesn't really matter.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-09T21:51:55.410" LastActivityDate="2015-01-09T21:51:55.410" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11593" PostTypeId="2" ParentId="11591" CreationDate="2015-01-09T21:23:17.523" Score="1" Body="&lt;p&gt;I don't think it much matters, and at almost all fields, Approach and Departure are on the same frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But to get really precise about it, I think you should consider it from the perspective of the facility you are contacting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying &lt;strong&gt;&lt;em&gt;towards&lt;/em&gt;&lt;/strong&gt; that facility, you are essentially approaching it (even if your destination is elsewhere), and should talk to Approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying &lt;strong&gt;&lt;em&gt;away&lt;/em&gt;&lt;/strong&gt; from that facility, talk to Departure.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-01-09T22:19:16.177" LastActivityDate="2015-01-09T22:19:16.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11594" PostTypeId="2" ParentId="11356" CreationDate="2015-01-09T22:08:24.550" Score="0" Body="&lt;p&gt;I wouldn't worry about something breaking in an airliner. The chance of that actually happening to you are orders of magnitude smaller than something breaking in your car on the way to the airport. Airline disasters make for much more sensational reading than car accidents do, so they tend to be hyped quite a bit more, but a major accident like that is really quite rare. Plus, there is so much that goes into inspecting those aircraft. Breaks do occur, but they are very rare. It's just not worth worrying about. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I'll go back to my original answer. Pilots are taught the proper ways to deal with a spin, and a spin is a spin is a spin. The specific aircraft aerodynamics differ, but the general procedures are still the same. However, if you're in an airliner that gets to the point of spinning, then it's more about the pilot than it is the aircraft. And if the pilot let the aircraft even approach a spin, he's the wrong guy to be sitting in that seat to begin with.&lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2015-01-09T22:08:24.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11595" PostTypeId="2" ParentId="9719" CreationDate="2015-01-09T23:36:37.410" Score="8" Body="&lt;p&gt;I'll echo many of the sentiments that have already been expressed: There's a discrepancy between what the ad describes and what the mechanic's prebuy report describes, which indicates that either the ad is &quot;hastily put together&quot; or intentionally misleading (neither is good). Also the idea that an engine was &quot;rebuilt&quot; but never logged is a huge red flag.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were I in your situation (and I was not too long ago) I would only consider purchasing this aircraft if you could talk to the inspecting mechanic in person (preferably while seeing the aircraft), and I would ask &lt;em&gt;their&lt;/em&gt; opinion on the condition of the airframe, engine, accessories, instruments, and avionics.&lt;br&gt;&#xA;In fact that is very good advice no matter how experienced you are at purchasing aircraft: Nothing beats an expert evaluation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To answer your question about the remaining life on an airframe and engine requires a deeper understanding of the plane you're looking to buy (again, &lt;strong&gt;&lt;em&gt;talk to your mechanic&lt;/em&gt;&lt;/strong&gt; about this - I really can't emphasize that enough).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'd be best served by first understanding what &lt;a href=&quot;https://aviation.stackexchange.com/questions/7430/what-is-the-difference-between-hobbs-time-and-tach-time&quot;&gt;Tach and Hobbs hours mean&lt;/a&gt;, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/7684/comparison-between-smoh-and-sfoh&quot;&gt;how engine time is described&lt;/a&gt;. Armed with that knowledge, let's forge on and figure out what times are important for this particular plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First you'll notice that the Tach and Hobbs times in the mechanic's report are different -- that's OK, they're probably never going to be exactly the same. You'll also notice that none of these numbers match the &quot;Time Since Major Overhaul&quot; for the engine -- that's also normal (TSMOH is a derived number - the current time minus the time when the last overhaul was done - so there's almost never a direct representation of it in the cockpit).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll also notice the Tach and Hobbs, and Total Time (airframe time) don't match up with the total time for the airframe. That's a bit of a red flag: Normally one of these is what's being recorded as &quot;Total Time - Airframe&quot; (TTAF), and if none of them match either the tach / hobbs meter was replaced at some point and not &quot;run up&quot; to match the airframe time, or there's a error in the ad as I mentioned earlier.&lt;br&gt;&#xA;Your mechanic should be able to tell you which situation you're in by a careful examination of the logs, and that should also reveal how many hours are on the engine and airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of argument I'm going to assume the &lt;em&gt;Tach&lt;/em&gt; time above is the Total Time - Airframe (about 8100 hours), and we'll go with 2100 hours since overhaul on the engine because that's what the logs apparently say.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So we've established the Total Time for the airframe (about 8100 hours), and the time since the engine was last overhauled (2100 hours) -- what does that &lt;em&gt;mean&lt;/em&gt;? How long will this plane last?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is there's no way to know just based on hours -- this is why we pay mechanics to do a thorough prebuy inspection. A 20,000 hour airframe that has had excellent maintenance could easily go another 20,000 hours, but a 2,000 hour airframe that has been abused and neglected may be ready to be scrapped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the engine, most GA Piston engines have a 2000 hour Time Between Overhaul (TBO) recommended by the manufacturer. Overhauling at this point isn't mandatory for most part 91 operations and well-cared-for engines can continue to operate for hundreds of hours beyond the recommended overhaul point with no problems, but generally if you're looking to buy an airplane an engine that's got 2100 hours on it will be considered &quot;run out&quot;. Consider your mechanic's opinion of this engine carefully, and have a plan in your mind as to what you're going to do when the engine needs to be torn down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the airframe 10,000 hours is usually considered to be &quot;high time&quot; (often these have been &quot;working airplanes&quot; - flight school trainers, etc.) - This doesn't mean the plane is worn out, but it bears special consideration in the inspection.&lt;br&gt;&#xA;Remember that nothing can ever &quot;reset&quot; airframe time the way overhauls or engine replacement can for an engine: The parts on that airframe have their accumulated time (and accumulated fatigue cycles) forever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 10,000 hour airframe can continue to give years of excellent service, with one major caveat: &lt;em&gt;Life-Limited Parts&lt;/em&gt;.  Some aircraft have components which have a maximum service life limit (for example, the wings on a Grumman AA-5 have a 12,000 hour life limit. Once reached the wings are no longer airworthy and must be replaced, and as Grumman is no longer making those planes you'd be hard pressed to find a replacement wing).&lt;br&gt;&#xA;In consultation with your mechanic you should consider the time remaining on any life-limited parts as well as the overall time on the airframe and its condition in order to ascertain how many more hours the plane can realistically fly for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes the numbers can be mind-boggling: When I was plane shopping I looked at a Cherokee 140 with 10,000 hours on the airframe. It was a flight school trainer, but somehow managed to get through its life with no major damage and had been meticulously maintained by the schools which owned it over the years. My mechanic's opinion was that it could easily fly another 20,000 hours or more if it continued to get the same kind of lavish care, which is more hours than many GA pilots will ever have in their logbooks. (Piper says the spar is good for 30,000 hours per Service Bulletin 886, after which they want it inspected).&lt;br&gt;&#xA;Other times the numbers can be soberingly obvious (like Grumman AA-5 with 11,500 hours - obviously a plane in the twilight years of its service life).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So what's the bottom line?&lt;br&gt;&#xA;The aircraft you're describing has mid-to-high time airframe by most standards.&lt;br&gt;&#xA;The engine is &quot;run out&quot; based on the time since it was last overhauled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both could continue to give years of excellent service, or they could fall apart tomorrow: The only way to have confidence either way is to find a mechanic who knows that particular type of aircraft, hire them, and have them go over the plane and logs. Then sit down with that mechanic and go over their findings.&lt;br&gt;&#xA;Your mechanic will tell you if the plane is a gem or a lemon, and if they know the aircraft type they've got a better idea what to look for than you, I, or most folks kicking around on the internet would.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-01-09T23:36:37.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11596" PostTypeId="1" CreationDate="2015-01-10T09:52:17.010" Score="14" ViewCount="6661" Body="&lt;p&gt;What happens if an engine fails between V&lt;sub&gt;1&lt;/sub&gt; and V&lt;sub&gt;2&lt;/sub&gt; on a modern twin airliner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, at V&lt;sub&gt;1&lt;/sub&gt; you have enough runway remaining to safely stop and abort the takeoff. V&lt;sub&gt;2&lt;/sub&gt; is the lowest single engine flying speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine is going to fail, surely it will be at the worst possible time.&lt;/p&gt;&#xA;" OwnerUserId="6781" LastEditorUserId="19" LastEditDate="2016-07-29T10:18:08.173" LastActivityDate="2016-07-29T10:18:08.173" Title="What happens if an engine fails between V1 and V2?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;engine-failure&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11597" PostTypeId="2" ParentId="11596" CreationDate="2015-01-10T10:30:21.430" Score="5" Body="&lt;p&gt;V&lt;sub&gt;1&lt;/sub&gt; is the decision speed, the decision being to continue the take off.  After this, you will take the failed engine into the air.  V&lt;sub&gt;2&lt;/sub&gt; and V&lt;sub&gt;R&lt;/sub&gt; do not change following an engine failure, nor will you stop accelerating.  Part 25 aircraft must be certified to be able to continue a take off with one engine after V&lt;sub&gt;1&lt;/sub&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;V&lt;sub&gt;1&lt;/sub&gt; is the critical engine failure recognition speed or&#xA;  takeoff decision speed. It is the decision speed nominated by the&#xA;  pilot which satisfies all safety rules, and above which the takeoff&#xA;  will continue even if an engine fails.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That said, there have been examples of RTOs between V&lt;sub&gt;1&lt;/sub&gt; and V&lt;sub&gt;2&lt;/sub&gt;.  &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/training/media/takeoff_safety.pdf&quot; rel=&quot;nofollow&quot;&gt;This FAA paper&lt;/a&gt; will give you lots of good data and examples of RTOs both before and after V&lt;sub&gt;1&lt;/sub&gt;.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="65" LastEditDate="2015-01-11T01:49:36.557" LastActivityDate="2015-01-11T01:49:36.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11598" PostTypeId="2" ParentId="11596" CreationDate="2015-01-10T11:35:27.143" Score="24" Body="&lt;p&gt;If an engine failure occurs above V&lt;sub&gt;1&lt;/sub&gt; the aircraft can accelerate to the V&lt;sub&gt;r&lt;/sub&gt; and take-off, retract gear and accelerate to V&lt;sub&gt;2&lt;/sub&gt; and pass the end of the runway at a height of at least 35 feet. From there, flying at V&lt;sub&gt;2&lt;/sub&gt; or above the aircraft can climb at angle that keeps it clear of nearby obstacles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the aircraft's certification is to demonstrate that this is possible. &#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3310/how-are-take-off-segments-defined&quot;&gt;This question is&lt;/a&gt; related to the exact requirements.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To determine the minimum runway length required, two scenarios are calculated. The first scenario has the aircraft accelerating to V&lt;sub&gt;1&lt;/sub&gt;, suffering an engine failure at V&lt;sub&gt;1&lt;/sub&gt; and then aborting the take-off. This gives the Accelerate - Stop Distance Required (ASDR). The higher V&lt;sub&gt;1&lt;/sub&gt;, the higher the ASDR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second scenario has the aircraft accelerating to V&lt;sub&gt;1&lt;/sub&gt;, suffering an engine failure at V&lt;sub&gt;1&lt;/sub&gt; and then continuing the take-off. This take-off involves accelerating from V&lt;sub&gt;1&lt;/sub&gt; to V&lt;sub&gt;r&lt;/sub&gt;, lifting off, retracting gear while accelerating and climbing, reaching V&lt;sub&gt;2&lt;/sub&gt; and 35 feet at the end of the runway. The runway length required for this scenario is the Take-Off Distance Required (TODR). The higher V&lt;sub&gt;1&lt;/sub&gt; the lower the TODR. This because when V&lt;sub&gt;1&lt;/sub&gt; is higher the part of the scenario that involves accelerating on a single engine becomes smaller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These calculations take into account aircraft weight, engine thrust, aircraft configuration and runway condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the V&lt;sub&gt;1&lt;/sub&gt; that gives the same ASDR as TODR, the required runway length is shortest. This is called the balanced field length. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=9KhZwsYtNDE&quot; rel=&quot;nofollow noreferrer&quot;&gt;video is an example&lt;/a&gt; of an engine failure between V&lt;sub&gt;1&lt;/sub&gt; and V&lt;sub&gt;2&lt;/sub&gt;. While the aircraft is rotating the engine ingests a heron resulting in big balls of fire. The aircraft lifts of, accelerates and climbs away at angle steep enough to avoid obstacles.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rejecting a take-off above V&lt;sub&gt;1&lt;/sub&gt; will likely result in a runway excursion. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-01-10T11:56:59.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11599" PostTypeId="2" ParentId="8270" CreationDate="2015-01-10T11:58:29.930" Score="1" Body="&lt;p&gt;Indepent engine MROs still have chances to work on sunset and mature engines only. However for the new generation engines the demonation will be by the OEMs only.Though, these shops will not be able to handle the shop visits by themselves but need to off load some of the work to indepenedent MROs like Jordan Airmotive,AF/KLM and others.&lt;/p&gt;&#xA;" OwnerUserId="6784" LastEditorUserId="556" LastEditDate="2015-01-10T18:54:25.863" LastActivityDate="2015-01-10T18:54:25.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11602" PostTypeId="1" AcceptedAnswerId="11603" CreationDate="2015-01-10T17:03:20.407" Score="31" ViewCount="7354" Body="&lt;p&gt;First, let me set this up and then ask a general question.  I'm just trying to give some context as to why I'm asking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm working on my private pilot license and was practicing with my PC simulator (X-plane) this weekend.  I was flying a Mooney m20j out of John Wayne (KSNA, which has two runways, 16R/1L 16L/1R).  I took off from 16R and at about 300AGL I encountered a bird strike and my engine died (though my windshield was intact).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was just about at the end of the runway so I declared an emergency (yeah, I've been talking to myself...) and said I was going to turn the plane around and land on 1R (so, the parallel runway in the opposite direction.)  I was kind of panicking and had no idea what to do, this was just the first thing that sprang to mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I started the turn and quickly realized I was sliding sideways towards the ground, so I leveled out the plane a bit and ended up making a short approach on a taxiway, which I managed to land (though that may be down to the simulator being a bit forgiving and not me, really.)  So the plane survived...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So I've got two questions, the first a little specific (though I'll try to generalize it) and the second nice and general so it applies to a wider audience.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Is the process I described a good approach to a bird strike during take off?&lt;/strong&gt;&lt;br&gt;&#xA;In review, I feel I probably would have been better off just landing straight ahead on a road or open field, but I thought I'd ask.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What is the best way to deal with a bird strike or incident on takeoff that fails the engine?&lt;/strong&gt;&lt;br&gt;&#xA;I'm particularly interested in situations where the plane is about at the end of the runway - if it happens right as you take off you can just put it back down, and if you're much higher up you have a lot of options because you can glide for a while.  But right at the runways end, when you have very little altitude and no more runway...  What's the proper procedure?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="511" LastEditorUserId="3386" LastEditDate="2017-11-03T13:21:42.077" LastActivityDate="2020-01-25T22:02:56.017" Title="What is the proper procedure after a bird strike in a single engine plane during takeoff?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;general-aviation&gt;&lt;takeoff&gt;&lt;bird-strike&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11603" PostTypeId="2" ParentId="11602" CreationDate="2015-01-10T17:25:28.960" Score="28" Body="&lt;p&gt;You will not find a &quot;single rule fits all&quot; but in general, on PPL training, you are taught &amp;lt; 700 feet, land ahead no matter what.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A skilled pilot, with good currency, in an aircraft they know well, in good conditions they have planned for and with enough altitude, might successfully turn around.  Another pilot in the same aircraft with the same conditions might kill themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The consequences of getting a turnaround wrong are worse then getting a straight ahead landing wrong and, by turning around, you might very well put someone else at risk.  You have much better prospects mushing down straight and level into those trees ahead than stalling out of a turn in an attempt to get back to somewhere you may or may not make.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Forget the flight sim heroics.  Nose down aggressively for best glide (you should already know what that looks like!), then start looking, or even better, go for the area you know is good because you pre-planned for an EFATO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line, when you do start training (good luck!), do whatever you are trained to do.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-03-12T22:21:49.847" LastActivityDate="2015-03-12T22:21:49.847" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11604" PostTypeId="1" AcceptedAnswerId="11607" CreationDate="2015-01-10T17:31:55.093" Score="0" ViewCount="1215" Body="&lt;p&gt;I've built a coaxial collinear antenna (16 arrays), according to &lt;a href=&quot;http://www.balarad.net/&quot; rel=&quot;nofollow&quot;&gt;this guide&lt;/a&gt; but having some issues picking up traffic from the West (?). I'm not very experienced in the area, so I've no idea where to start or why this is happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The antenna is located in my living room and is aprox. 2 meters.&lt;/p&gt;&#xA;" OwnerUserId="6790" LastEditorUserId="1696" LastEditDate="2016-07-06T21:56:41.323" LastActivityDate="2016-07-06T21:56:41.323" Title="How can I improve the reception of my coaxial collinear antenna (1090 MHz)?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2015-01-11T14:55:09.210" ContentLicense="CC BY-SA 3.0" />
  <row Id="11606" PostTypeId="2" ParentId="11602" CreationDate="2015-01-10T18:24:14.667" Score="13" Body="&lt;p&gt;A real life emergency is not a chance for trying unnecessary risky moves, especially new ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the AOPA seminars (I forgot which one) actually mentioned such a situation: an engine failure very shortly after take off in a GA plane. They did some tests in Microsoft Flight Simulator 2004, executing the 180 turn with varying degrees of bank. In the sim, if you bank steep enough (at least 60, or even 75), you have a good chance of making it to the runway. But then...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In real life, when you bank, you increase the stall speed. Worse, if you feel you can't make the turn, you may be prompted to pull back, increasing your stall speed even further. Now, you end up with a accelerated stall at a steep bank, engine failure, and very little altitude to work with!!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best approach is to try at perhaps 3000 feet. Apply takeoff power, pitch up to take off attitude, then pull back throttle to simulate a sudden loss of power (don't forget to clear the area of traffic beforehand). Work out how much altitude is necessary to execute the turn, which varies from airplane to airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying, it is best if you have a predetermined turn/no-turn altitude. If you don't know, either figure it out or ask your instructor. There is very little altitude, and very little time to think. If you're below that altitude, don't think about it, land straight ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instructor, who is an aerobatic pilot, can perform a &quot;stall turn&quot; (a.k.a. &quot;hammer head&quot;) to turn the plane around. If executed correctly, the plane should end up in the opposite direction with almost no lost of altitude or speed. Bear in mind, though, this is because he has done this many many times, so he is confident to execute it a low altitude. Do not try this if you have never done it!&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-10T18:24:14.667" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11607" PostTypeId="2" ParentId="11604" CreationDate="2015-01-10T19:01:26.653" Score="4" Body="&lt;p&gt;If the antenna is located in your living room, then the incoming 1090 MHz signals will be blocked by your house. 1090MHz signals are more-or-less line of sight. They don't travel very far through concrete or wood and are severely attenuated by glass, especially is you have energy efficient windows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect you have a window towards the East or South East so that you have some signal reception from that direction. Try to put the antenna outside, preferably on top of your house to improve your signal reception. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-10T19:06:39.620" LastActivityDate="2015-01-10T19:06:39.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11608" PostTypeId="1" AcceptedAnswerId="11616" CreationDate="2015-01-10T20:28:28.097" Score="22" ViewCount="2858" Body="&lt;p&gt;On the &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_32&quot;&gt;Qantas Flight 32&lt;/a&gt; incident, the Airbus A380's number two engine suffered from an uncontained engine rotor failure and partially damaged the controls of number one engine as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Wikipedia, engines one and four entered a 'degraded mode' after the explosion, and number one could not be shut off after landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it seems that in case an engine loses all communication signals from the aircraft's control systems in the cockpit, it could somehow remain operational.  To me that definitely sounds a lot safer compared to shutting down and risking the plane lose all thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So do jet engines, by design, keep producing thrust in case they lose contact with the control systems?&lt;/p&gt;&#xA;" OwnerUserId="3151" LastEditorDisplayName="user12485" LastEditDate="2016-01-30T22:56:40.233" LastActivityDate="2016-01-30T22:56:40.233" Title="Does a jet engine keep running when it can no longer be controlled from the cockpit?" Tags="&lt;safety&gt;&lt;jet-engine&gt;&lt;engine-failure&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11610" PostTypeId="1" CreationDate="2015-01-08T11:46:47.307" Score="4" ViewCount="53" Body="&lt;p&gt;Few days ago I took a flight to go back to my town. Towards the end of the journey, the captain demanded us to &lt;strong&gt;shut down&lt;/strong&gt; any electronic device that we had on board, including iPods, CD players, phones and so on. Reason: there was very low visibility and we had to start the &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow&quot;&gt;instrumented landing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I could understand, an instrumented landing system allows and aircraft to be centred on the lane assisted by signals delivered by an ILS (a localiser and a glide slope), so to arrange the maneuver without visibility. This signals are in the  110 MHz (LOC) and 330 MHz (GS) frequency range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that for the take off, &quot;manual&quot; landing and the journey itself, shutting off the devices is not required any longer (and there are signals travelling even there I would guess, at least for what concern communication with the base and all the ariplane intra-components communications), why is that instead required for an assisted landing? What interferences could a CD Player possibly produce on the instrumentation to an extent that it's more dangerous than with the usual take off - flying - landing phases?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note: as you probably understood, my level of expertise is very low, so forgive any dumb mistake or oversight.&lt;/p&gt;&#xA;" OwnerUserId="6752" OwnerDisplayName="Nicola Miotto" LastEditorUserId="609" LastEditDate="2015-01-11T03:34:31.883" LastActivityDate="2015-01-11T03:34:31.883" Title="Instrumented landing: why switching *everything* off" Tags="&lt;instrument-procedures&gt;&lt;electronics&gt;" AnswerCount="0" CommentCount="0" FavoriteCount="0" ClosedDate="2015-01-11T05:23:16.743" ContentLicense="CC BY-SA 3.0" />
  <row Id="11612" PostTypeId="2" ParentId="11555" CreationDate="2015-01-08T12:00:09.713" Score="8" Body="&lt;p&gt;The only reason electronic devices are demanded to be switched off is because some of them affect the radio (telephones) and it's easier to say &quot;shut them all off&quot; than to argue over which equipment is susceptible to interfere with the radio and ask the crew to carefully inspect whether the device at the other end of your earbuds is actually a telephone or a CD player.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: actually asked the question to my aerobatics instructor a few years back. He told me that when the phones weren't switched off it happened that he had to ask Control to repeat 2 to 3 times before understanding them.&lt;/p&gt;&#xA;" OwnerDisplayName="Mister Mystère" LastActivityDate="2015-01-08T12:00:09.713" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11613" PostTypeId="2" ParentId="9425" CreationDate="2015-01-11T05:02:20.000" Score="3" Body="&lt;p&gt;Depending on the jet engine type and on the cause and amount of damage, an engine repair or module replacement could be carried out on the wing. If damage or further investigation is needed, or if the aircraft is needed quickly, the engine could be removed to the airline's engine shop and parts/module/modules replaced on site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further damage may dictate the engine goes back to the manufacturer's overhaul shop or an approved overhaul facility: The engine will be stripped and each part inspected for serviceability. The cost of repair will be calculated. If the repair cost is higher than a new engine cost, the insurance company may deem it &quot;beyond economical repair&quot; and the engine is scrapped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the repair cost is acceptable then the engine may be repaired or fully overhauled depending on the operating hours/cycles already accrued in service: A low-hour damaged engine may just be repaired, whilst it would be more economical to fully overhaul a high-hour damaged engine to bring it back to &quot;nil hours since last overhaul status&quot;.&lt;/p&gt;&#xA;" OwnerUserId="6761" LastEditorUserId="11671" LastEditDate="2018-04-22T18:43:12.350" LastActivityDate="2018-04-22T18:43:12.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11614" PostTypeId="2" ParentId="9462" CreationDate="2015-01-11T05:30:22.457" Score="12" Body="&lt;p&gt;My experience shows that, on some short haul domestic type operations, some pilots practice shutting down the left wing-mounted engine quickly after landing to be sure the engine has stopped turning to allow passengers to disembark down the steps. The quick turnaround operation may mean another engine start within 30 minutes of shut down. The core (heavy turbine discs) is still hot whereas the lighter weight and exterior turbine cases have cooled and contracted onto the turbine airseals. This can lead to &quot;seal squeal&quot; if the engine is windmilling in the wind and attracts ground engineers' attention, or in severe cases may lock the core engine shaft. In most cases, allowing the engine to fully cool or, if possible, restarting the engine, allow 10 mins at idle to fully expand all parts equally and recut the turbine airseals, the engine can be deemed serviceable if all other parameters are normal. Continued use by pilots of this practice would mean for the engine to quickly lose performance, mostly seen as increased fuel consumption, through premature airseal deterioration.&lt;/p&gt;&#xA;" OwnerUserId="6761" LastEditorUserId="1961" LastEditDate="2015-01-11T09:08:45.967" LastActivityDate="2015-01-11T09:08:45.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11615" PostTypeId="2" ParentId="1609" CreationDate="2015-01-11T06:31:26.527" Score="1" Body="&lt;p&gt;The higher the altitude the thinner the atmoshere means less air resistance or  drag on the airplane so it needs less engine thrust to push it. Thats lucky because the engine loses thrust with altitude at almost the same rate because as less air is available to the engine, the fuel system must reduce fuel to maintain the correct air/fuel ratio to support combustion and keep the engine alight. Its a win win situation.&lt;/p&gt;&#xA;" OwnerUserId="6761" LastActivityDate="2015-01-11T06:31:26.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11616" PostTypeId="2" ParentId="11608" CreationDate="2015-01-11T07:34:06.980" Score="22" Body="&lt;p&gt;General rule here: the engine will remain at its last power setting should the FADECs lose comms with the flight deck controls (in your A380 case) or the thrust lever cables come unhooked (in the case of an older aircraft with mechanical cable-and-pulley controls).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the fire handle will kill the engine even if the main controls fail -- it operates the firewall fuel and hydraulic shutoff valves.  In QF32, this didn't happen because the cable for the #1 engine fire handle itself was damaged by shrapnel entering the wing.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-01-11T07:34:06.980" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11617" PostTypeId="2" ParentId="11555" CreationDate="2015-01-11T11:17:21.387" Score="19" Body="&lt;p&gt;Having worked as a software engineer on the lateral guidance subsystem of the FMCS (Flight Management and Control System) for the Airbus A310 about 30 years ago I found @reirab's answer fascinating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can fill in some gaps as to how the information from the different systems is used and why the ILS information is particularly critical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the A310 3 sets of input are used in determining the aircraft's position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Every 200ms the inertial data from the set of 3 laser gyroscopes are used to basically say - &quot;I was there. For 200ms I have been travelling at x knots therefore now I am here&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Every 1.5 seconds (in normal flight) data from up to 4 DMEs and VORs are used to accurately calculate the position of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) During landing when ILS or MLS is available the ILS/MLS data is used in place of DME/VOR data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two significant differences between 2) and 3). Because you are closer to the ground and precise vertical as well as lateral position is critical calculations are performed more frequently than once every 1.5 seconds. Because ILS/MLS data is much more accurate filtering of position adjustment is reduced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does that mean? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, when I do the radio position fix using DME and VOR I will also have an inertially calculated position. For various reasons beyond just not spilling the passengers' coffee I'm not allowed to correct this position by more than something like 5m (this is different if there has been no radio fix for a prolonged period of time). With ILS/MLS this filter factor is much larger, like 50m or even 100m, although the expectation is that such a large correction will only happen on initially acquiring the ILS/MLS signal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because such large corrections of the aircraft calculated position are allowed in Flight Management software when using ILS/MLS data it is critically important that there are no errors due to interference.&lt;/p&gt;&#xA;" OwnerUserId="6796" LastActivityDate="2015-01-11T11:17:21.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11618" PostTypeId="1" AcceptedAnswerId="11634" CreationDate="2015-01-12T01:02:26.123" Score="4" ViewCount="2437" Body="&lt;p&gt;The Evektor Harmony LSA &amp;amp; RV-12 SLSA have all the necessary equipment to be certified for IFR flight, except the only engines allowed for purchase are the Rotax 912 ULS &amp;amp; iS. These engines are not allowed in IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt; Can these planes be certified for IFR, despite the IMC limitation?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;em&gt;if no&lt;/em&gt;, can they be used for training for one's instrument rating and for the instrument rating checkride?&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;if yes&lt;/em&gt;, then if one were to be flown into IMC, would be this be a legal violation or a warranty violation?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="65" LastEditDate="2015-01-12T02:00:57.427" LastActivityDate="2021-02-26T02:05:29.383" Title="Can a plane be IFR certified, but not allowed in IMC?" Tags="&lt;instrument-flight-rules&gt;&lt;imc&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11619" PostTypeId="1" CreationDate="2015-01-12T02:32:06.017" Score="8" ViewCount="3632" Body="&lt;p&gt;Is a stand-alone magnetic compass required for an IFR fight when the aircraft has a glass panel with a &lt;a href=&quot;http://en.wikipedia.org/wiki/Horizontal_situation_indicator&quot;&gt;Horizontal Situation Indicator&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="6806" LastEditorUserId="511" LastEditDate="2015-01-12T07:42:01.397" LastActivityDate="2015-01-12T18:20:36.877" Title="Is a magnetic compass required for an IFR flight?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11620" PostTypeId="2" ParentId="11619" CreationDate="2015-01-12T08:37:04.560" Score="7" Body="&lt;p&gt;A magnetic heading indicator is required, but not necessarily a wet compass, like this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RvX9H.jpg&quot; alt=&quot;Magnetic Compass / Panel mounted&quot;&gt;&lt;br&gt;&lt;sup&gt;Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Aero_Magnetic_Compass.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia - Author: Chopper&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Digital devices or combined devices are also possible:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ov6R8.png&quot; alt=&quot;HSI&quot;&gt;&lt;br&gt;&lt;sup&gt;Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Horizontal_situation_indicator-en.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiPedia - Author: Mysid&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The required equipment for &lt;strong&gt;VFR&lt;/strong&gt; flights states, as already posted in &lt;a href=&quot;https://aviation.stackexchange.com/questions/7995/is-a-magnetic-compass-required-for-vfr&quot;&gt;this question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.205&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.205&lt;/a&gt;   Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(3) Magnetic direction indicator.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The text further states for &lt;strong&gt;IFR&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) Instrument flight rules. For IFR flight, the following instruments and equipment are required:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(1) Instruments and equipment specified in paragraph (b) of this section, and, for night flight, instruments and equipment specified in paragraph (c) of this section.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-12T18:15:57.563" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11621" PostTypeId="1" AcceptedAnswerId="11622" CreationDate="2015-01-12T09:59:02.623" Score="14" ViewCount="1770" Body="&lt;p&gt;The ASK-21 is mainly a fibreglass construction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the bearings for the airbrakes and their control rods are fitted into small pieces (some 10 cm wide) of what seems to be plywood molded into the fibreglass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following picture shows the plate holding the bearing for the airbrake, seen from the rear side in the space in the fuselage where the wing spars are joined. The bolt that sticks out holds the bearing of the linkage that transfers the brake movement to the rods in the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5nn0r.jpg&quot; alt=&quot;The plywood plate holding the bearing for the airbrake, seen from behind&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last picture shows the bearings in the wing where the rod to lift the actual air brake is fastened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X5ouL.jpg&quot; alt=&quot;The bearing for the rod that lifts the air brake &quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this choice of material - could the bearings not be fitted into the fibreglass structure without extra pieces of plywood?&lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="2176" LastEditDate="2015-01-18T23:36:32.963" LastActivityDate="2019-05-10T10:18:54.613" Title="Why use plywood to hold the bearings for the airbrakes on a fibreglass glider?" Tags="&lt;glider&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11622" PostTypeId="2" ParentId="11621" CreationDate="2015-01-12T10:18:07.900" Score="16" Body="&lt;p&gt;This use of plywood is not ideal, but it works. The wood soaks up the epoxy and becomes an integral part of the fiberglass construction, and is easy to mold, so laying up the same geometry from glass fibers alone would be much more laborious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, plywood is reasonably &lt;a href=&quot;http://en.wikipedia.org/wiki/Isotropy&quot; rel=&quot;nofollow noreferrer&quot;&gt;isotropic&lt;/a&gt;, at least in the two directions of the plywood layers. If you want to achieve similar isotropy with glass fibers, you need to interweave them - just wrapping one roving around the bearing will not do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could use other materials - aluminum would do, but doesn't bond as well to the epoxy resin. That &lt;a href=&quot;http://www.alexander-schleicher.de&quot; rel=&quot;nofollow noreferrer&quot;&gt;Schleicher&lt;/a&gt; uses plywood has historic reasons. They used to build gliders with wood, some had steel tube fuselages, but wood was their primary construction material. When they started to build glass fiber gliders (the first was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Schleicher_ASW_12&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASW-12&lt;/a&gt;, which was a commercial version of the &lt;a href=&quot;http://www.akaflieg.tu-darmstadt.de/geschichte/d-36/&quot; rel=&quot;nofollow noreferrer&quot;&gt;D-36&lt;/a&gt;, on which &lt;a href=&quot;http://en.wikipedia.org/wiki/Gerhard_Waibel_(engineer)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gerhard Waibel&lt;/a&gt; cut his teeth as a glider designer and won the German gliding championship in 1964) they used what they knew best. And it worked.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-12-17T17:53:35.443" LastActivityDate="2018-12-17T17:53:35.443" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="11625" PostTypeId="1" AcceptedAnswerId="11630" CreationDate="2015-01-12T12:51:57.883" Score="26" ViewCount="13718" Body="&lt;p&gt;There have been some gruesome deaths involving ground staff being sucked into jet engines, presumably because the engine thrust was set well above idle. Are there safety features (besides prudence on the flight deck) that are designed to mitigate this risk?&lt;/p&gt;&#xA;" OwnerUserId="558" LastActivityDate="2015-01-13T03:30:54.060" Title="What safety features prevent jets sucking in ground staff or equipment?" Tags="&lt;safety&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11626" PostTypeId="1" AcceptedAnswerId="11678" CreationDate="2015-01-12T13:15:50.963" Score="13" ViewCount="1680" Body="&lt;p&gt;I am over 6' 2&quot; and endured an extremely unpleasant 9-hour flight last year.  Shorter folk were just fine. Are there any guidelines or regulations for seat legroom on airlines?&lt;/p&gt;&#xA;" OwnerUserId="6812" LastEditorUserId="679" LastEditDate="2015-01-13T09:00:17.267" LastActivityDate="2018-10-07T15:13:20.073" Title="Are there any guidelines or regulations for seat legroom on airlines?" Tags="&lt;airliner&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11627" PostTypeId="1" CreationDate="2015-01-12T13:21:53.437" Score="18" ViewCount="8100" Body="&lt;p&gt;Is there a particular reason why FDRs and CVRs and associated similar bits of equipment are kept in the tail section of a plane?&lt;/p&gt;&#xA;" OwnerUserId="6813" LastEditorUserId="22726" LastEditDate="2019-04-17T21:46:03.600" LastActivityDate="2019-04-18T11:14:26.653" Title="Why are flight recorders generally located in the tail?" Tags="&lt;aircraft-design&gt;&lt;flight-recorders&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11628" PostTypeId="2" ParentId="11621" CreationDate="2015-01-12T13:27:00.860" Score="10" Body="&lt;p&gt;For some bearings, you need a sufficent thickness of the socket and supporting structure to deal with bending moments on the rods/bolts, plus you need to transfer the point loads into the wing structure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plywood is well suited for this task, while being lighter, cheaper and easier to build &lt;em&gt;and&lt;/em&gt; machine than aluminum or fibre-reinforced plastics. Together with the top glass laminate you get a lightweight, yet sturdy structure (essentially a sandwich). As already stated, (ply-)wood is a surprisingly fabulous material.&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2015-01-12T15:15:39.733" LastActivityDate="2015-01-12T15:15:39.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11629" PostTypeId="2" ParentId="11627" CreationDate="2015-01-12T13:43:21.537" Score="11" Body="&lt;p&gt;The reason for the FDR and CVR to be located in the rear of the aircraft is because that gives the best chances of recovering them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually an aircraft has a forward speed when it crashes. The initial shock of impact is absorbed by the forward part of the aircraft, resulting in a more gradual deceleration for the aft parts as the aircraft breaks up. By putting the FDR and CVR in the back the acceleration is reduced allowing for a higher probability of them remaining intact. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="2171" LastEditDate="2015-01-13T00:46:40.157" LastActivityDate="2015-01-13T00:46:40.157" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11630" PostTypeId="2" ParentId="11625" CreationDate="2015-01-12T14:07:51.597" Score="35" Body="&lt;p&gt;No, there are no safety &lt;em&gt;features&lt;/em&gt;. Only safety &lt;em&gt;procedures&lt;/em&gt; on the flight deck and on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it all boils down to that nobody may go near any aircraft (jet or prop; they are both similarly dangerous) that may have engines running. When starting the engines, the pilots first turn on the beacon (the red flashing lights on the belly and tail), then check the ground crew has left and only then start the engine(s). And similarly upon landing, the pilots shut the engines down, wait a bit to let them spool down and turn off the beacons; then the ground crew should ask (via radio or the wired intercom connected to a socket at the nose) whether the engines are indeed off and only then they may start working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since start-up normally only happens after push-back, so away from the terminal, there is usually no risk then. Upon arrival however the ground crew needs to come to the aircraft relatively quickly and insert chocks to the wheels, so the correct procedures are important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=46a4ba8a&quot;&gt;Here see a recent accident&lt;/a&gt; where ground worker was injured because the procedures were not followed (he was coming from the rear, so he was only blown away, not sucked in).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that incident, the engines &lt;strong&gt;were at idle.&lt;/strong&gt; They are still very dangerous in that case. I found an Airbus document which shows danger areas, for A320 with CFM56 engines, &lt;strong&gt;at idle&lt;/strong&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;suction danger 2.2m (7.2ft) from engines (semicircle forward and to the sides of the engine and back to 1.5m behind the inlet) and&lt;/li&gt;&#xA;&lt;li&gt;exhaust danger to 55m (180ft) behind the nozzles with 30° spread with exhaust velocity exceeding 105km/h (65mi/h) for 17m (55ft) aft of the nozzles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At full power the suction area grows to 5.9m (19.5ft) radius and the exhaust danger to 275m (900ft) with velocity over 105km/h down to 150m (500ft) aft.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="65" LastEditDate="2015-01-12T16:02:05.320" LastActivityDate="2015-01-12T16:02:05.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11631" PostTypeId="2" ParentId="11619" CreationDate="2015-01-12T14:27:31.360" Score="4" Body="&lt;p&gt;If you mean a &quot;whiskey compass,&quot; like the thing that sits above the center of the panel, then the answer is &lt;strong&gt;no&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LW3gB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft certified under Part 23, as described in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1311-1C.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 23.1311-1C&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Section 23.1303(c), Amendment 23-62, amended the requirement from “A&#xA;  direction indicator (non-stabilized magnetic compass)” to “A magnetic&#xA;  direction indicator.” As new technology becomes more affordable for&#xA;  part 23 airplanes, many &lt;strong&gt;electronic flight instrument systems will use&#xA;  magnetically stabilized direction indicators&lt;/strong&gt; (or electric compass&#xA;  systems) to measure and indicate the airplane heading to provide&#xA;  better performance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Fluxgate_compass&quot; rel=&quot;nofollow noreferrer&quot;&gt;fluxgate compass&lt;/a&gt;, which can be remotely mounted in the wing or the tail would also satisfy the regs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;http://en.wikipedia.org/wiki/Microelectromechanical_systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;MEMS&lt;/a&gt; fluxgates are being developed right now, which could be integrated directly into an &lt;a href=&quot;http://en.wikipedia.org/wiki/Attitude_and_heading_reference_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;AHRS&lt;/a&gt;. And there are &lt;a href=&quot;http://www.sensorsmag.com/sensors/electric-magnetic/a-new-perspective-magnetic-field-sensing-855&quot; rel=&quot;nofollow noreferrer&quot;&gt;a number of other technologies&lt;/a&gt; being developed to sense the earth's magnetic field.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-12T18:20:36.877" LastActivityDate="2015-01-12T18:20:36.877" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11632" PostTypeId="2" ParentId="11625" CreationDate="2015-01-12T14:32:39.807" Score="16" Body="&lt;p&gt;Ground operations are complicated and dangerous. You can find some details about risks and hazard zones associated with operations on the ground, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_06/textonly/s02txt.html&quot; rel=&quot;noreferrer&quot;&gt;here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Precautions taken to minimize risk are (among others:)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Everyone must be clearly visible. Ground personnel always wears high visibility clothes including high visibility vests, and trousers with high reflectivity stripes (even during the day.) The tarmac is well lit. Operations cease on extremely low-visibility situations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cockpit to ground communications: The ground will inform the cockpit that they are cleared to start-up the engines. The ground crew will make sure that no person or object is in the hazard zones of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A special indicator light will be on when the engines are about to be started/are running (for example: the Anti-Collision light for the B737, and the Beacon light for the A320.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_blast_deflector&quot; rel=&quot;noreferrer&quot;&gt;Jet blast deflectors&lt;/a&gt; are used where necessary. This went infamously wrong in &lt;a href=&quot;http://avherald.com/h?article=438945f6/0000&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; instance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.aerospaceweb.org/question/propulsion/q0233a.shtml&quot; rel=&quot;noreferrer&quot;&gt;The spirals painted on jet-engine spinners &lt;/a&gt; are used as visual cues from the ground crew that the engine is on (this is somewhat anecdotal: the spiral on a spinner that is slow-spinning because of the wind will be still visible as a spiral but the spiral becomes a gray point if the engine is spinning while it is in operation.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airport signs and ground markings, such as these:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Mlf19.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/aSkwu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ground marshaller and wingwalker signals&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uHvMF.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/LrELd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="3504" LastEditDate="2015-01-12T16:03:43.627" LastActivityDate="2015-01-12T16:03:43.627" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11633" PostTypeId="2" ParentId="11627" CreationDate="2015-01-12T15:55:12.817" Score="27" Body="&lt;p&gt;When an aircraft is crashed, the entire front of the aircraft is expected to act as a &lt;em&gt;crush zone&lt;/em&gt;. By placing FDRs and CVRs near the tail, the shock wave that reaches FDRs and CVRs is reduced significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The probability of survival based on seating is shown in this picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5CMUP.gif&quot; alt=&quot;Survival chances&quot;&gt;&lt;br/&gt;&#xA;&lt;sup&gt;&lt;em&gt;(&lt;a href=&quot;http://www.joeydevilla.com/wordpress/wp-content/uploads/2007/07/safest-seats-on-the-plane.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;)&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence one can see that the shock wave reduces as it reaches the rear of the plane. That is the reason FDRs and CVRs are installed in aircraft's empennage section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lEvIq.gif&quot; alt=&quot;Location of data recorders&quot;&gt;&lt;br/&gt;&#xA;&lt;sup&gt;&lt;em&gt;(&lt;a href=&quot;http://news.bbcimg.co.uk/media/images/45996000/gif/_45996239_black_box_loc_v2_466_v2.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;)&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Please note that the precise location of the recorders depends on the individual plane. Sometimes they are located in the ceiling of the galley, in the aft cargo hold or in the tail cone that covers the rear of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2019-04-18T11:14:26.653" LastActivityDate="2019-04-18T11:14:26.653" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="11634" PostTypeId="2" ParentId="11618" CreationDate="2015-01-12T17:24:36.917" Score="7" Body="&lt;p&gt;&lt;em&gt;Question: Can these planes be certified for IFR, despite the IMC limitation?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Refer to  &lt;a href=&quot;http://fsims.faa.gov/WDocs/8700.1%20GA%20Ops%20Insp%20Handbk/Volume%202/2_008_00.htm&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 8700.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;B.  Type Certificate Data. Appropriate type certificate data will&#xA;  indicate whether the aircraft meets the requirements for IFR&#xA;  operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Section 91.9(a)prohibits aircraft operations without compliance&#xA;  with the operating limitations for that aircraft prescribed by the&#xA;  certificating authority.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;if no, can they be used for training for one's instrument rating and for the instrument rating checkride?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, as per &lt;a href=&quot;http://fsims.faa.gov/WDocs/8700.1%20GA%20Ops%20Insp%20Handbk/Volume%202/2_008_00.htm&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 8700.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;9.  USE OF AIRCRAFT NOT APPROVED FOR IFR OPERATIONS UNDER ITS TYPE CERTIFICATE FOR INSTRUMENT TRAINING AND/OR AIRMAN CERTIFICATION&#xA;  TESTING.  The following paragraphs are intended to clarify the use of&#xA;  an aircraft not approved for IFR operations under its type certificate&#xA;  for instrument flight training and/or airman certification testing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A.  IFR Training in Visual Meteorological Conditions (VMC). Instrument&#xA;  flight training may be conducted during VMC in any aircraft that meets&#xA;  the equipment requirements of part 91, 91.109 , 91.205 , and, for an&#xA;  airplane operated in controlled airspace under the IFR system, 91.411&#xA;  and 91.413 . An aircraft may be operated on an IFR flight plan under&#xA;  IFR in VMC, provided the PIC is properly certificated to operate the&#xA;  aircraft under IFR. However, if the aircraft is not approved for IFR&#xA;  operations under its type certificate, or if the appropriate&#xA;  instruments and equipment are not installed or are not operative,&#xA;  operations in Instrument Meteorological Conditions (IMC) are&#xA;  prohibited. The PIC of such an aircraft must cancel the IFR flight&#xA;  plan in use and avoid flight into IMC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For example, you can &lt;a href=&quot;http://www.hillsboroaviation.com/en/for_sale/helicopter/new_robinson/robinson_r-44_raven_ii_ifr_trainer&quot; rel=&quot;noreferrer&quot;&gt;obtain an Instrument--Rotorcraft in an R44&lt;/a&gt;, even though its not legal in IMC.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although the R44 IFR Trainer was designed for instrument flight&#xA;  training, it is not approved for actual IFR operations. While student&#xA;  pilots are flying on instruments, the instructor must act as the&#xA;  safety pilot and operate only under VFR conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1wXBi.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;if yes, then if one were to be flown into IMC, would be this be a legal violation or a warranty violation?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be a legal violation of 91.9(a)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;91.9(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating&#xA;  limitations specified in the approved Airplane or Rotorcraft Flight&#xA;  Manual, markings, and placards, or as otherwise prescribed by the&#xA;  certificating authority of the country of registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-12T17:57:56.570" LastActivityDate="2015-01-12T17:57:56.570" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11635" PostTypeId="2" ParentId="8702" CreationDate="2015-01-12T18:06:55.963" Score="3" Body="&lt;p&gt;Under &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/29.1527&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR Part 29.1527&lt;/a&gt;, the Maximum operating altitude for a transport-category helicopter is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 29.1527 Maximum operating altitude.&#xA;  The maximum altitude up to which operation is allowed, as limited by&#xA;  flight, structural, powerplant, functional, or equipment&#xA;  characteristics, must be established.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So its not just a matter of power or thrust, or even just retreating blade stall, but rather the entire design envelope for the helicopter must be taken into consideration for maximum altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the Robinson R-66 has a number of operating limitations that pertain to factors other than maximum thrust: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gCsnv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And there is a Vne chart which limits forward speed to prevent retreating blade stall at high density altitude:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UNtCG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-17T13:49:55.780" LastActivityDate="2015-01-17T13:49:55.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11637" PostTypeId="5" CreationDate="2015-01-12T19:20:20.023" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:20:20.023" LastActivityDate="2015-01-12T19:20:20.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11638" PostTypeId="4" CreationDate="2015-01-12T19:20:20.023" Score="0" Body="Ailerons are the control surfaces on the wing that provide roll control. " OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:20:20.023" LastActivityDate="2015-01-12T19:20:20.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11639" PostTypeId="5" CreationDate="2015-01-12T19:25:17.223" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:25:17.223" LastActivityDate="2015-01-12T19:25:17.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11640" PostTypeId="4" CreationDate="2015-01-12T19:25:17.223" Score="0" Body="Fuel dumping is a procedure used by aircraft in certain emergency situations before a return to the airport shortly after take-off, or before landing short of its destination to reduce the landing weight." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:25:17.223" LastActivityDate="2015-01-12T19:25:17.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11641" PostTypeId="5" CreationDate="2015-01-12T19:27:00.353" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:27:00.353" LastActivityDate="2015-01-12T19:27:00.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11642" PostTypeId="4" CreationDate="2015-01-12T19:27:00.353" Score="0" Body="Aerodynamic drag is the fluid drag force that acts on any moving solid body in the direction of the fluid freestream flow. Part of the drag is the direct consequence of the wing generating lift. " OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:27:00.353" LastActivityDate="2015-01-12T19:27:00.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11643" PostTypeId="5" CreationDate="2015-01-12T19:34:09.383" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:34:09.383" LastActivityDate="2015-01-12T19:34:09.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11644" PostTypeId="4" CreationDate="2015-01-12T19:34:09.383" Score="0" Body="Density altitude is a measure of air density. It is the altitude where the air density under ICAO Standard Atmosphere conditions is equal to the actual density. On hot days, the density altitude is above the pressure altitude, on cold days it is below. Density altitude is an important factor for aircraft performance modelling." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:34:09.383" LastActivityDate="2015-01-12T19:34:09.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11645" PostTypeId="5" CreationDate="2015-01-12T19:39:37.397" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:39:37.397" LastActivityDate="2015-01-12T19:39:37.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11646" PostTypeId="4" CreationDate="2015-01-12T19:39:37.397" Score="0" Body="A radar transponder is a radio beacon on an aircraft that replies to a radar interrogation. The transponder encodes information into the reply, allowing air traffic control to know the aircraft's altitude and identity." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T19:39:37.397" LastActivityDate="2015-01-12T19:39:37.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11647" PostTypeId="5" CreationDate="2015-01-12T20:09:27.450" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T20:09:27.450" LastActivityDate="2015-01-12T20:09:27.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11648" PostTypeId="4" CreationDate="2015-01-12T20:09:27.450" Score="0" Body=" Questions dealing with regulations promulgated by the Civil Aviation Authority (CAA) of the United Kingdom." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T20:09:27.450" LastActivityDate="2015-01-12T20:09:27.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11649" PostTypeId="5" CreationDate="2015-01-12T20:14:54.127" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-12T20:14:54.127" LastActivityDate="2015-01-12T20:14:54.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11650" PostTypeId="4" CreationDate="2015-01-12T20:14:54.127" Score="0" Body="The Rotax 912 is a normally aspirated, air- and water-cooled, four-stroke,  four-cylinder engine commonly used on certified aircraft, light sport aircraft, and ultralight aircraft." OwnerUserId="19" LastEditorUserId="22726" LastEditDate="2019-10-03T00:12:01.197" LastActivityDate="2019-10-03T00:12:01.197" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="11651" PostTypeId="2" ParentId="2266" CreationDate="2015-01-12T20:20:38.777" Score="11" Body="&lt;p&gt;For safety purpoes, in order for an aircraft to be certified under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_11357&quot;&gt;14 CFR 23&lt;/a&gt;, it must meet the following requirement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§23.1357   Circuit protective devices.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Protective devices, such as fuses or circuit breakers, must be&#xA;  installed in all electrical circuits other than—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Main circuits of starter motors used during starting only; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Circuits in which no hazard is presented by their omission.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) A protective device for a circuit essential to flight safety may&#xA;  not be used to protect any other circuit.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each resettable circuit protective device (“trip free” device in&#xA;  which the tripping mechanism cannot be overridden by the operating&#xA;  control) must be designed so that—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A manual operation is required to restore service after tripping;&#xA;  and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) If an overload or circuit fault exists, the device will open the&#xA;  circuit regardless of the position of the operating control.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(d) If the ability to reset a circuit breaker or replace a fuse is&#xA;  essential to safety in flight, that circuit breaker or fuse must be so&#xA;  located and identified that it can be readily reset or replaced in&#xA;  flight.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) For fuses identified as replaceable in flight—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) There must be one spare of each rating or 50 percent spare fuses&#xA;  of each rating, whichever is greater; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The spare fuse(s) must be readily accessible to any required&#xA;  pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2003-title14-vol1/pdf/CFR-2003-title14-vol1-sec25-1383.pdf&quot;&gt;aircraft certified under 14 CFR 25&lt;/a&gt;, there is similar wording:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 25.1357 Circuit protective devices. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Automatic protective devices&#xA;  must be used to minimize distress to the electrical system and hazard&#xA;  to the airplane in the event of wiring faults or serious malfunction&#xA;  of the system or connected equipment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The protective and control devices in the generating system must&#xA;  be designed to de-energize and disconnect faulty power sources and&#xA;  power transmission equipment from their associated busses with&#xA;  sufficient rapidity to provide protection from hazardous over-voltage&#xA;  and other malfunctioning.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each resettable circuit protective device must be designed so&#xA;  that, when an overload or circuit fault exists, it will open the&#xA;  circuit irrespective of the position of the operating control.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(d) If the ability to reset a circuit breaker or replace a fuse is&#xA;  essential to safety in flight, that circuit breaker or fuse must be&#xA;  located and identified so that it can be readily reset or replaced in&#xA;  flight.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Each circuit for essential loads must have individual circuit&#xA;  protection. However, individual protection for each circuit in an&#xA;  essential load system (such as each position light circuit in a&#xA;  system) is not required.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) If fuses are used, there must be spare fuses for use in flight&#xA;  equal to at least 50 percent of the number of fuses of each rating&#xA;  required for complete circuit protection.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) Automatic reset circuit breakers may be used as integral&#xA;  protectors for electrical equipment (such as thermal cut-outs) if&#xA;  there is circuit protection to protect the cable to the equipment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-12T20:29:36.733" LastActivityDate="2015-01-12T20:29:36.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11652" PostTypeId="2" ParentId="9074" CreationDate="2015-01-12T22:50:11.753" Score="-1" Body="&lt;p&gt;I am the US, but here you can amend a flight plan while in air.  I have done this several times to change the destination from airport X to airport Y.  ATC nicely updated my clearance to the new destination.&lt;/p&gt;&#xA;" OwnerUserId="2953" LastActivityDate="2015-01-12T22:50:11.753" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11654" PostTypeId="2" ParentId="11625" CreationDate="2015-01-13T03:30:54.060" Score="5" Body="&lt;p&gt;Spool down times for various engine types allow ramp agents like me to routinely avoid being ingested.i.e when &#xA;Aircraft is coming up the j-line via direction from ramp agent the rest of the crew maintains a safe distance from the approaching aircraft until appropriate time passes per aircraft at arrival. You can only get ingested once in your life but you can get blasted by jets several times.&lt;/p&gt;&#xA;" OwnerUserId="6823" LastActivityDate="2015-01-13T03:30:54.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11656" PostTypeId="2" ParentId="11627" CreationDate="2015-01-13T07:37:45.557" Score="9" Body="&lt;p&gt;In addition to Farhan's excellent answer, it should be noted that reducing the peak impact shock is not the only reason that the FDR is placed in the tail, and that the passenger survivability is higher behind the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings are full of fuel, and when the tanks rupture during a crash the fuel tends to spill &lt;em&gt;forward&lt;/em&gt;. If you look at crash videos you will notice two common scenarios:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;In incidents in which the plane scrapes along the runway, friction with the ground starts a fire. In this scenario the &lt;em&gt;rear&lt;/em&gt; of the plane is engulfed in flames, but that is the exterior. When the plane comes to rest, either the whole vehicle is engulfed or the fire recedes to small flames on the parts touching the ground: the engines and undercarriage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In incidents in which the plane collides with the ground and does not scrape, the fuselage and wings rupture and fuel spills forward. In these cases the fires are &lt;em&gt;mostly&lt;/em&gt; in the front portion of the craft, and the broken fuselage allows the fire to quickly spread to the interior of the craft. These fires are much more dramatic and look like explosions due to the high quantity of fuel and fuel vapor being available.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="354" LastActivityDate="2015-01-13T07:37:45.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11657" PostTypeId="1" AcceptedAnswerId="11661" CreationDate="2015-01-13T11:26:29.053" Score="14" ViewCount="15348" Body="&lt;p&gt;In some airshows, I have seen some big aircraft (like 737) takeoff almost vertical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, fully-loaded passenger/cargo planes don't do that, I guess due to safety issues but I think there needs a lot of extra thrust to have an almost vertical takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is a vertical takeoff possible in every kind of airplane (without excessive weight and giving full thrust) or only some specific ones can do it?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="64" LastEditDate="2015-01-13T16:31:36.470" LastActivityDate="2017-04-28T17:57:28.807" Title="How much thrust is needed by an aircraft to have vertical takeoff?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11658" PostTypeId="1" CreationDate="2015-01-13T11:42:19.397" Score="23" ViewCount="13833" Body="&lt;p&gt;If I'm going on holiday with my family on an airliner such as &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airliners_by_maximum_takeoff_weight&quot; rel=&quot;noreferrer&quot;&gt;one of the ones listed on this page&lt;/a&gt;, then where is the safest place to sit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answers to this question seem to imply that the seats at the rear of the plane would be safer:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11627/why-are-flight-recorders-generally-located-in-the-tail&quot;&gt;Why are flight recorders generally located in the tail?&lt;/a&gt; &lt;br&gt;&#xA;but of course I can think of quite a few things which might make it different for passengers versus the flight recorder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realise that flying is statistically a lot safer than driving, so I don't need to be told not to worry about safety - I'm not worrying, I'm just interested in the difference in safety between different seats in the airliner. Because if I get a choice of seats then (&lt;a href=&quot;http://en.wikipedia.org/wiki/Ceteris_paribus&quot; rel=&quot;noreferrer&quot;&gt;ceteris paribus&lt;/a&gt;) I can't see any reason not to choose the safer ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing it might be affected by things like proximity to the exits, and so might be different in different models of airliner. If that's the case then can you tell me what factors &lt;em&gt;affect&lt;/em&gt; the safety of each seat? E.g. is it more important to be close to an exit or to be further back in the plane? What should I look for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it different on long-haul versus short-haul? Or are there other differences in the type of flight (and therefore the more typical type of accident) which change the 'safest place to sit'? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A few articles I've found on the topic: &lt;br&gt;&#xA; - &lt;a href=&quot;http://www.popularmechanics.com/technology/aviation/safety/4219452&quot; rel=&quot;noreferrer&quot;&gt;Popular Mechanics, 2007&lt;/a&gt; (statistical review: back is safest) &lt;br&gt;&#xA; - &lt;a href=&quot;http://www.discovery.com/tv-shows/curiosity/topics/discovery-channel-crashed-727/&quot; rel=&quot;noreferrer&quot;&gt;Discovery / Channel 4, 2013&lt;/a&gt; (one-off crash experiment: back is safest) &lt;br&gt;&#xA; - &lt;a href=&quot;http://www.bbc.co.uk/sn/tvradio/programmes/horizon/broadband/tx/survivorsguide/top_tips/index_textonly.shtml&quot; rel=&quot;noreferrer&quot;&gt;BBC, 2014&lt;/a&gt; (expert opinion: no safest place) &lt;br&gt;&#xA; - &lt;a href=&quot;http://www.caa.co.uk/docs/33/2006_01.pdf&quot; rel=&quot;noreferrer&quot;&gt;CAA, 2006&lt;/a&gt; (statistical review of evacuations: exit rows and adjoining rows are safest)&lt;/p&gt;&#xA;" OwnerUserId="4067" LastEditorUserId="22550" LastEditDate="2019-01-07T04:27:07.980" LastActivityDate="2019-12-18T15:48:48.757" Title="Where is the safest seat in the plane?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;passenger&gt;&lt;accident-statistics&gt;&lt;evacuation&gt;" AnswerCount="8" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11659" PostTypeId="1" AcceptedAnswerId="11660" CreationDate="2015-01-13T12:03:46.647" Score="11" ViewCount="7762" Body="&lt;p&gt;Is there any restriction by FAA that one can not fly a plane older than 'X' years?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone is maintaining an older plane (e.g. from 1990s), are there any regulations which prevents or restricts that person to fly that airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am interested in finding out both for commercial and smaller general aviation airplanes.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="13197" LastEditDate="2016-04-25T11:51:39.960" LastActivityDate="2017-09-20T22:56:33.367" Title="Is there any limit by FAA on the age of aircraft to be operational?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11660" PostTypeId="2" ParentId="11659" CreationDate="2015-01-13T12:23:23.350" Score="13" Body="&lt;p&gt;It depends on the aircraft, but in general the answer is that there  are no regulatory age limitations, and indeed we have many aircraft flying that are 50+ years old. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A notable exception is the Robinson line of piston helicopters. &lt;a href=&quot;http://www.robinsonheli.com/manuals/r44_mm/r44_mm_3.pdf&quot;&gt;The airframe on those helis is limited to 2200 hours or 12 years&lt;/a&gt;, whichever comes first, at which point the entire airframe must be completely overhauled. Some of the airframes are indeed rebuilt, but some are also scrapped, depending on level of wear and corrosion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the airframe lifetime is in the LIMITATIONS section of the POH, it is governed by:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.9 Civil aircraft flight manual, marking, and placard&#xA;  requirements. (a) Except as provided in paragraph (d) of this section,&#xA;  no person may operate a civil aircraft without complying with the&#xA;  operating limitations specified in the approved Airplane or Rotorcraft&#xA;  Flight Manual, markings, and placards, or as otherwise prescribed by&#xA;  the certificating authority of the country of registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-13T16:08:19.620" LastActivityDate="2015-01-13T16:08:19.620" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11661" PostTypeId="2" ParentId="11657" CreationDate="2015-01-13T12:23:33.583" Score="24" Body="&lt;p&gt;First, let's agree on terminology: What you saw in airshows is a vertical flight path. Flying horizontally first, the airplane pitched up until the nose was pointing straight into the sky.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surprisingly, no thrust is needed to perform this maneuver. Even gliders can do it. What happens is that kinetic energy is converted to potential energy, the rate of potential energy increase being proportional to flight speed and aircraft mass. If you start fast enough, this vertical flying can be maintained for several seconds, until the aircraft runs out of speed and stops in midair, followed by an uncontrolled drop. Skilled pilots orient the aircraft in the right direction by starting a rotation around the vertical axis at the top of the climb, so the following drop lets them pick up speed again with the correct nose-down attitude. Now potential energy is converted back into kinetic energy until speed is sufficient for a pullout. In aerobatics, this maneuver is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_turn&quot;&gt;a stall turn or a hammerhead stall.&lt;/a&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few conditions apply, however. The airplane must be able to fly fast enough to have the needed potential energy to sustain the maneuver through the pitch-up phase. This is helped if its engines add energy, so the kinetic energy bleeds off more slowly. Also, at the top of the maneuver it is flying at zero g, and this requires at least that all items on board are securely fastened. Lastly, the pitch-up needs a load factor bigger than 1 g, and the higher the maximum load factor is, the tighter this pitch-up can be flown.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now the question has been changed: The vertical flight path is flown right after take-off. This limits the entry speed for the maneuver, and gliders will not be able to do this. If we take the 737 from the question and fly it with no payload and little fuel, the flight mass $m$ of a 737-700 is 40&amp;nbsp;tons, and the installed thrust is about 200&amp;nbsp;kN (sea level static). Let's assume that the pilot accelerates after takeoff to a horizontal speed $v$ = 100&amp;nbsp;m/s (194&amp;nbsp;KTAS) while retracting the flaps, the kinetic energy ($0.5\cdot m\cdot v^2$) is equivalent to a potential energy ($m \cdot g \cdot h$) of an altitude gain h of $$h = \frac{v^2}{2\cdot g} = 510 m$$&#xA;The engines deliver less thrust with increasing speed; maybe 40% of the weight, so the airplane will still accelerate for the first 18° - 20° of the 90° flight path change. This will delay the point when speed has been bled off and add maybe 150&amp;nbsp;m to h. At 100&amp;nbsp;m/s a pull-up with a radius of 500&amp;nbsp;m will add a load factor of 2&amp;nbsp;g. The pilot needs to pull less first and harder at the end of the maneuver in order to stay within the &lt;a href=&quot;http://home.scarlet.be/ppleducation/Limitations%20737.pdf&quot;&gt;maximum load factor of 2.5&lt;/a&gt;. When speed bleeds off, so will wing lift, and in the second half of the pull-up the wing will not create enough lift to change the flight path enough in order to reach the desired vertical attitude. Also, the aircraft will be very low for a safe recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This makes it rather doubtful that an airliner can be pulled up to a vertical climb after takeoff. If the maneuver is started at a higher speed and with a little more distance from the ground, I see no reason why it should not safely be possible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-13T23:18:24.780" LastActivityDate="2015-01-13T23:18:24.780" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11662" PostTypeId="2" ParentId="11657" CreationDate="2015-01-13T12:29:34.640" Score="8" Body="&lt;p&gt;For a craft weighing &lt;code&gt;x kg&lt;/code&gt; you need &lt;code&gt;g*x Newtons&lt;/code&gt; of thrust minimum for &lt;em&gt;sustained vertical flight&lt;/em&gt; (ref.: high-school physics). In other words for each metric ton of weight you need around 9.81 kN of thrust. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380#Specifications&quot;&gt;A380&lt;/a&gt; has a operational empty weight of 276 t so it would need 2707 kN of thrust to sustain a vertical climb. Its 4 engines each producing 320kN don't even come halfway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However pitching up to vertical and continuing on &lt;em&gt;while shedding speed&lt;/em&gt; is possible without thrust.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-13T13:38:54.483" LastActivityDate="2015-01-13T13:38:54.483" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11663" PostTypeId="2" ParentId="11658" CreationDate="2015-01-13T12:49:20.347" Score="19" Body="&lt;p&gt;There is no general safe or unsafe seat rule - it really depends on the circumstances of any mishap. If the plane runs into a mountain, the rear seats give you more crush zone, so the deceleration is lower and stretched out over time to sustainable levels. However, if the plane &lt;a href=&quot;http://avherald.com/h?article=464ef64f&amp;amp;opt=4096&quot; rel=&quot;nofollow noreferrer&quot;&gt;comes in too low during landing&lt;/a&gt; and strikes ground first with the tail, those rear seats will see the highest acceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might as well look into the historical records of the particular type of aircraft - see &lt;a href=&quot;https://aviation.stackexchange.com/questions/8370/why-does-the-boeing-737-have-5-x-the-passenger-fatalities-of-the-airbus-320&quot;&gt;this question&lt;/a&gt; for some numbers. However, to use this as the basis of a risk assessment would be an abuse of statistics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another factor might be the airline: How well do they maintain the aircraft, and how well are the pilots prepared to handle an emergency? There are multiple studies which look into the &lt;a href=&quot;http://hci.ucsd.edu/media/uploads/hci_papers/EH2002-2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;different cultures&lt;/a&gt; around the world and how much they contribute to the accident rate. Some report a tripling of accidents between the unsafest and the safest cultures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect that by choosing a safe airline you will have the highest influence on the safety of the trip, but unfortunately the desire of passengers to pick the cheapest flights no matter what has led operators to cut corners wherever they can.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-01-13T12:55:10.427" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11664" PostTypeId="2" ParentId="11659" CreationDate="2015-01-13T14:22:11.913" Score="5" Body="&lt;p&gt;According to Wikipedia the &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-3&quot; rel=&quot;noreferrer&quot;&gt;DC-3&lt;/a&gt;  first flew in 1935, entered regular passenger service in 1936, and as of 2012 #10 off the production line was still in regular commercial service. I'd venture to say it's got more to do with maintenance than regulation. (I'm sure someone will quote the appropriate FAR section in a few minutes.)&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-01-13T14:22:11.913" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11665" PostTypeId="2" ParentId="11659" CreationDate="2015-01-13T14:33:07.437" Score="6" Body="&lt;p&gt;Aircraft hulls are limited in the wear and tear they can withstand due to metal fatigue that can develop (pressurized aircraft more than non-pressurized).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer will impose limits on the flight time of the hull (an older airframe will be considered not airworthy) so any developing metal fatigue will not tear apart the plane in flight like what happened with the &lt;a href=&quot;https://en.wikipedia.org/wiki/BOAC_Flight_781&quot; rel=&quot;nofollow&quot;&gt;Comet&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;nofollow&quot;&gt;Aloha Airlines flight 243&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;tl;dr it's the responsibility of the manufacturer to impose limits on the airframe age.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-13T15:58:49.553" LastActivityDate="2015-01-13T15:58:49.553" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11666" PostTypeId="1" AcceptedAnswerId="11670" CreationDate="2015-01-13T14:51:16.733" Score="10" ViewCount="3266" Body="&lt;p&gt;As far as I understand, two of the reasons how an airfoil generates lift are &lt;a href=&quot;http://en.wikipedia.org/wiki/Coand%C4%83_effect&quot;&gt;Coandă effect&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Downwash&quot;&gt;downwash&lt;/a&gt;. However, if there is upwash near the leading edge, why isn't an airfoil rotated by the two forces (upwash at the front and downwash at the back of an airfoil)?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="65" LastEditDate="2015-01-13T15:17:23.117" LastActivityDate="2015-05-07T20:17:14.223" Title="Why doesn't an airfoil rotate?" Tags="&lt;airfoil&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11667" PostTypeId="2" ParentId="11659" CreationDate="2015-01-13T14:53:07.747" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://oldrhinebeck.org/ORA/bleriot-xi/&quot; rel=&quot;noreferrer&quot;&gt;N60094&lt;/a&gt;, a 1909 Bleriot XI based at Rhinebeck Aerodrome Museum, &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N60094&quot; rel=&quot;noreferrer&quot;&gt;has a valid FAA airworthiness certificate&lt;/a&gt;.  So I think it's safe to assume there are no FAA restrictions based solely on age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xn8QS.jpg&quot; alt=&quot;[N60094&quot;&gt;]&lt;a href=&quot;http://oldrhinebeck.org/ORA/bleriot-xi/&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="414" LastActivityDate="2015-01-13T14:53:07.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11668" PostTypeId="2" ParentId="11666" CreationDate="2015-01-13T14:53:56.320" Score="2" Body="&lt;p&gt;If the airfoil is cambered (in other words unsymmetric looking sideways) it does indeed rotate. This is why the control surfaces are needed with a preferably long moment arm and why building flying wings is difficult.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-01-13T14:53:56.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11669" PostTypeId="2" ParentId="11666" CreationDate="2015-01-13T14:54:44.150" Score="3" Body="&lt;p&gt;Because the horizontal stabilizers provide a counter force to the plane in its entirety so the pitch remains stable.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-13T14:54:44.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11670" PostTypeId="2" ParentId="11666" CreationDate="2015-01-13T15:06:03.623" Score="11" Body="&lt;p&gt;There are no two (aerodynamic) forces. Force is not caused by the up- or downwash itself, but by the change from up- to downwash. The air is only accelerated downward and this change in it's momentum causes an upward force on the wing everywhere, there is no aerodynamic down force. Due to the pressure distribution however the centre of lift is about quarter-chord for subsonic airfoils and changes somewhat with changes in attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There however obviously is a down force, gravity. If the centre of gravity and centre of pressure are offset relative to each other, there is a moment that rotates the aircraft. That's why a plane needs horizontal stabilizer with elevators that allow shifting the centre of lift by adding a bit of controllable lift far from the centre of lift of the main wing.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="4108" LastEditDate="2015-01-14T11:31:33.677" LastActivityDate="2015-01-14T11:31:33.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11671" PostTypeId="2" ParentId="11658" CreationDate="2015-01-13T15:45:59.817" Score="22" Body="&lt;p&gt;Before I start, remember that we're talking about statistics of location in the aircraft, within statistics of survival of an accident (95%), which is itself dependent on a statistic of particular type of accident (approx 85% have no fatalities at all), within something which is already a very unlikely event (an aviation accident).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let us for a moment assume that you're in a semi-survivable accident, ie where there are a mixture of fatalities and survivors - this is already a very unlikely scenario... in the vast majority of accidents either everybody dies (rare), or nobody does (most common).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give you the straight out answer to your question, in such an accident, the rear of the plane is safest - more passengers have survived plane crashes in those seats than any other. This is due to most accidents being nose-first, so if it's going to be partially survivable your ideal location is near the back: the front of the aircraft essentially acting like a crumple zone. Thus, if an accident is survivable, you are more likely to survive in the back of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, every accident is different - if your aircraft runs off the runway and spins, the back can impact first. Similarly if your aircraft stalls and pitches up. Alternately you could slew sideways into another aircraft in a taxiway etc etc... but in most cases, the impact is more likely to be nose-first, thus the rear is the safest place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also statistically, being near to a door but not next to a window gives the &quot;optimum&quot; chance of survival - more people survive in such locations. This is due to ease of evacuation (being near the aisle and the exit), and without being whacked in the head by a crumpling fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So if you're going on purely &quot;increasing your chances&quot;, a non-window seat near the rear door is the best possible place to be in an accident... other than on the ground, having missed your plane.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing to remember, though, is that (referring to modern aviation)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Accident rates work out as roughly 1-per-1 million flights&lt;/li&gt;&#xA;&lt;li&gt;Around 85-87% of aviation accidents involve no fatalities (so fatal accidents are around 15-per-100 million flights)&lt;/li&gt;&#xA;&lt;li&gt;Even if you're in a crash where &lt;em&gt;someone&lt;/em&gt; dies, Aviation accidents with fatalities have a fatality rate of somewhere between 5% and 25% (which is to say, even if we only look at accidents where one or more people do die, 75-95% of people in those accidents survive).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So that gives you a 1/4th to 1/20th of a chance of a 3/20th of a chance of a 1 in a million chance of becoming a statistic in my next post on this subject. So that would take you somewhere between 20 and 100 million flights before you die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have a 1-in-100-million chance of being in a fatal accident, and even then you a 75-95% chance of surviving it anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in short, if it's going to get you it will, if it's not it won't. By the time you've survived enough accidents for it to be anything more then sheer atrocious luck that you die at all, you'd already have developed a healthy fear of flying and have gathered enough air miles to take a taxi....&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2019-12-18T15:48:48.757" LastActivityDate="2019-12-18T15:48:48.757" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="11672" PostTypeId="2" ParentId="11658" CreationDate="2015-01-13T15:50:27.160" Score="2" Body="&lt;p&gt;Just based on your articles I guess it is fairly straightforward to pick a seat with high survivability:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Behind the wings, close to an emergency exit&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, keep in mind that if your family has small children, or if you worry a lot about things like what the safest seat in a plane is, you may want to avoid sitting next to emergency exits. They are used best if the person next to them keeps their head cool and opens it in times of crisis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such the best seat for you may be the row next to the emergency exit.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You may want to sit next to the aisle, but then again you probably gain more by letting each child be accompanied by an adult, so this is only relevant if there are more than 2 seats next to each window.&lt;/p&gt;&#xA;" OwnerUserId="6834" LastActivityDate="2015-01-13T15:50:27.160" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11673" PostTypeId="2" ParentId="11658" CreationDate="2015-01-13T15:53:59.817" Score="0" Body="&lt;p&gt;In April 2012, a group of scientists remotely piloted an airplane and performed a staged crash in Mexico. The aircraft they used was an unmanned Boeing 727-200, fitted with numerous cameras, sensors, and crash test dummies. They simulated the most likely type of aircraft crash landing, a controlled but too fast decent where the plane flew straight into the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each seat and it's 'passengers' had sensors on them that demonstrated the amount of stress on that point of the plane during impact. The program seemed to conclude that in that type of crash, again the most common type to occur, the front and back 25% of the aircraft was the most severely affected and where the majority of the fatalities / serious injuries would occur. The middle of the plane, particularly those just over the wing faired the best. There is of course no way to predict what could happen, every plane and situation completely different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The whole thing was filmed for television, an interesting watch although if you are a nervous flyer probably to be avoided! I believe it was called 'Curiosity: Plane Crash'&lt;/p&gt;&#xA;" OwnerUserId="6835" LastActivityDate="2015-01-13T15:53:59.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11674" PostTypeId="2" ParentId="11666" CreationDate="2015-01-13T15:57:31.163" Score="6" Body="&lt;p&gt;Perhaps you're thinking of something like a &lt;a href=&quot;http://www.fanwing.com&quot; rel=&quot;noreferrer&quot;&gt;fanwing&lt;/a&gt;, which incorporates both centrifugal fans and an airfoil into the wing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nryEc.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-13T15:57:31.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11675" PostTypeId="1" AcceptedAnswerId="11715" CreationDate="2015-01-13T16:18:18.713" Score="8" ViewCount="900" Body="&lt;p&gt;I want to know what aerodynamic noise an airliner makes when flying with &lt;strong&gt;both engines shut down&lt;/strong&gt;. Specifically, it is the sound made by air passing a plane which is in landing configuration, with gear and flaps extended, at a normal approach speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that it makes a loud noise especially during landing, but normally we cannot distinguish it from the engine sound.&lt;/p&gt;&#xA;" OwnerUserId="6836" LastEditorUserId="755" LastEditDate="2015-01-14T16:22:36.447" LastActivityDate="2015-01-14T16:26:50.200" Title="What does aerodynamic noise of an airliner sound like in landing configuration?" Tags="&lt;aerodynamics&gt;&lt;landing&gt;&lt;airliner&gt;&lt;jet-engine&gt;&lt;noise&gt;" AnswerCount="1" CommentCount="15" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11676" PostTypeId="2" ParentId="11657" CreationDate="2015-01-13T16:21:06.037" Score="4" Body="&lt;p&gt;Despite the hype that some news articles like to add to their stories, with talk of &quot;near-vertical&quot; takeoffs and &quot;terrifying&quot; turns, those maneuvers are less extreme than they look. While certainly higher than normal, &lt;a href=&quot;http://www.wired.com/2014/07/watch-test-pilots-push-the-new-boeing-jet-to-terrifying-limits/&quot; rel=&quot;nofollow&quot;&gt;30 degree pitch after takeoff or 60 degrees of bank&lt;/a&gt; are not vertical. Yet the air show still &lt;a href=&quot;http://blogs.seattletimes.com/boeing/2014/07/16/dueling-test-planes-for-airbus-and-boeing-at-farnborough-air-show/&quot; rel=&quot;nofollow&quot;&gt;said that was too much&lt;/a&gt;, so typical displays of non-aerobatic planes are going to be even less than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question in the title, take a look at the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_AV-8B_Harrier_II&quot; rel=&quot;nofollow&quot;&gt;AV-8B Harrier II&lt;/a&gt; attack jet. It has a max vertical takeoff weight of 20755 lb, and its engine produces 23500 lbf of thrust. This corresponds to a thrust-to-weight ratio of about 1.13:1, since the thrust must exceed the force of gravity in order to accelerate the plane upwards. In contrast, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;787-9 from the above example&lt;/a&gt; has 142,000 lbf of thrust, and weighs between 304,000 lb and 557,000 lb. If the plane weighed 400,000 lb on that takeoff, the thrust-to-weight ratio was about 0.36:1. Although converting kinetic energy to potential energy will allow a plane to climb faster, the amount of kinetic energy available to an airliner at takeoff is more limited.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-01-13T16:21:06.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11677" PostTypeId="1" AcceptedAnswerId="11683" CreationDate="2015-01-13T16:22:52.227" Score="6" ViewCount="4336" Body="&lt;p&gt;How do the airlines prepare for a situation where for some reason both PIC and SIC are incapacitated for the remainder of the flight? &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="22550" LastEditDate="2018-12-14T18:00:28.573" LastActivityDate="2018-12-14T18:00:28.573" Title="If both pilots are incapacitated, what happens?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;commercial-operations&gt;&lt;pilot-incapacitation&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11678" PostTypeId="2" ParentId="11626" CreationDate="2015-01-13T16:49:17.197" Score="10" Body="&lt;p&gt;The short answer is no, beyond the need for an aircraft to satisfy the &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/125.189&quot;&gt;emergency evacuation requirements&lt;/a&gt; set by the FAA and other regulators. There must also be room for an approved seat cushion and seatbelts. So there is a point where a lack of legroom would impede evacuation to the extent that an aircraft couldn't pass the &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1019850&quot;&gt;90 second evacuation requirement&lt;/a&gt;, but there's generally no specific minimum legroom requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main exception is in the UK, which does have a form of &lt;a href=&quot;http://www.skyscanner.net/news/leg-room-how-much-will-you-get&quot;&gt;minimum requirement&lt;/a&gt; (according to that link, the UK is the only country with one). The requirement is given as a different form of measurement from how airline seat pitch is normally defined, but the above link indicates that it basically translates to a 28-inch seat pitch. That's about as &lt;a href=&quot;http://www.seatguru.com/charts/shorthaul_economy.php&quot;&gt;low as any airline goes&lt;/a&gt;, namely Spirit in the US. Most airlines draw the line at 30&quot;, with a few low cost carriers doing 29&quot;&lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2015-01-13T16:49:17.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11679" PostTypeId="1" AcceptedAnswerId="11682" CreationDate="2015-01-13T18:25:20.063" Score="9" ViewCount="1348" Body="&lt;p&gt;After the recent announcement of the recovery of the flight recorders of &lt;a href=&quot;http://en.wikipedia.org/wiki/Indonesia_AirAsia_Flight_8501&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirAsia flight&lt;/a&gt; were recovered, I was wondering if black boxes deteriorate after a set amount of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of now, nothing of the plane &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot; rel=&quot;nofollow noreferrer&quot;&gt;MH370&lt;/a&gt; has been recovered, including either of the flight recorders. In &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;another downed flight in the past&lt;/a&gt;, it took over two years for the for the black boxes to be recovered from the ocean, and even then the information in the black boxes were intact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So do these black boxes ever expire? Or do they always keep the information intact throughout the years?&lt;/p&gt;&#xA;" OwnerUserId="1797" LastEditorUserId="22726" LastEditDate="2019-04-17T21:41:15.353" LastActivityDate="2019-04-17T21:41:15.353" Title="After a crash, does the information stored on flight recorders have expiration dates?" Tags="&lt;flight-recorders&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11680" PostTypeId="2" ParentId="11679" CreationDate="2015-01-13T18:53:47.260" Score="6" Body="&lt;p&gt;Every aviation accident is different. The aircraft flight data recorder is designed to survive likely scenarios, but successful recovery of the data stored on it is not guaranteed. Wikipedia has a &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_unrecovered_flight_recorders&quot; rel=&quot;noreferrer&quot;&gt;List of unrecovered flight recorders&lt;/a&gt; which is related.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no predetermined amount of time that a flight data recorder might &quot;keep&quot; its information intact. The data is stored on solid state devices these days, so presumably the information would be recoverable as long as the enclosure remains watertight and the internal temperature does not exceed the physical limits of the components. Neither of those conditions are assured and the information may be lost at any time.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-01-13T18:53:47.260" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11681" PostTypeId="1" AcceptedAnswerId="11684" CreationDate="2015-01-13T19:16:17.373" Score="2" ViewCount="1414" Body="&lt;p&gt;By all definitions that my team and I have found, fly-by and short-turn (with respect to military unmanned air vehicle waypoint based flight) mean the same thing.  Briefly, this allows the pilot to fly within a capture distance of the waypoint but is not required to fly directly over or through it.  In other words, the pilot can start turning before the waypoint is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current Definition:&#xA;A short turn will be performed at the turn location.  A short turn indicates that the vehicle may begin its turn prior to reaching the waypoint and fly-by it instead of through or over it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any nuanced difference between these two states so that I might further clarify this in my definition?&lt;/p&gt;&#xA;" OwnerUserId="3235" LastEditorUserId="19" LastEditDate="2016-11-15T14:32:50.667" LastActivityDate="2016-11-15T14:32:50.667" Title="What is the difference between Fly-By and Short-Turn?" Tags="&lt;navigation&gt;&lt;terminology&gt;&lt;waypoint&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11682" PostTypeId="2" ParentId="11679" CreationDate="2015-01-13T19:37:30.913" Score="9" Body="&lt;p&gt;&lt;strong&gt;Everything&lt;/strong&gt; will expire one day, including &lt;a href=&quot;https://en.wikipedia.org/wiki/Sun#Life_phases&quot; rel=&quot;noreferrer&quot;&gt;our Sun&lt;/a&gt;. Flight recorders are no exception.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older flight recorders used magnetic tapes. They used to work like any other &lt;a href=&quot;https://en.wikipedia.org/wiki/Tape_recorder&quot; rel=&quot;noreferrer&quot;&gt;tape recorder&lt;/a&gt;. At present, &lt;a href=&quot;http://en.wikipedia.org/wiki/Solid-state_drive&quot; rel=&quot;noreferrer&quot;&gt;solid-state memory&lt;/a&gt; boards are used. These are considered much more reliable than magnetic tapes, because no moving parts are involved like magnetic tapes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data from both recorders is stored on stacked memory boards inside the crash-survivable memory unit (CSMU). A &lt;a href=&quot;http://www.l-3ar.com/Draft_0612/html/AU-FAQ-CSMU_txt.php&quot; rel=&quot;noreferrer&quot;&gt;CSMU is&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... is collectively the solid-state memory chips and a hardened metal&#xA;  container filled with specially designed heat insulating material. It&#xA;  is this container that provides the survivability, for it is able to&#xA;  withstand massive crushing loads, intense heat, and exceptionally high&#xA;  G forces, all of which is proven by crash survivability testing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sSTQ7.jpg&quot; alt=&quot;Flight Recorder&quot;&gt;&#xA;&lt;br/&gt;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://farm5.static.flickr.com/4013/4688341726_6cbfd140b6.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that the memory boards are inside stainless steel shell, which is designed to withstand the crash. Although there is a limit of writes on solid state memory, after a crash there are no more writes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the FDRs/CVRs are recovered from a crash scene, there are various methods to retrieve data, depending on the condition of flight recorders. This process can take weeks or months to complete.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Further reading: &lt;a href=&quot;http://science.howstuffworks.com/transport/flight/modern/black-box.htm/printable&quot; rel=&quot;noreferrer&quot;&gt;How Black Boxes Work&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2018-02-05T15:48:04.447" LastActivityDate="2018-02-05T15:48:04.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11683" PostTypeId="2" ParentId="11677" CreationDate="2015-01-13T20:16:47.197" Score="14" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow noreferrer&quot;&gt;How does Airbus prepare for a dual engine failure on the A320?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is this isn't something that's realistically planned for because the chance of a double-failure of the redundant systems in question (the two pilots) is pretty unlikely, and many of the conditions that could lead to it would result in a catastrophic loss of the aircraft anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The most notable exception to that would be a loss of pressurization at altitude, in which case hopefully at least &lt;em&gt;one&lt;/em&gt; of the pilots can get their oxygen mask on to make the emergency descent.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The ATC/Airline system as a whole can &lt;em&gt;theoretically&lt;/em&gt; deal with this sort of a double failure in a few different ways. The most common is finding an off-duty employee of the airline who is riding non-revenue (dead-head, jumpseat, etc.) to fill the role of an incapacitated crew member.&lt;br&gt;&#xA;This is of course predicated on whatever incapacitated the flight crew not affecting this other person.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If no qualified personnel are available it may be possible to get an experienced instructor on the radio to &quot;talk the plane down&quot;, but that relies on having someone onboard who can (a) get access to the cockpit, and (b) at least figure out how to operate the radios to ask for help.&lt;br&gt;&#xA;&quot;Talk-Down Landings&quot; have happened &lt;a href=&quot;http://abcnews.go.com/US/story?id=96248&quot; rel=&quot;nofollow noreferrer&quot;&gt;in small aircraft&lt;/a&gt; on several occasions, but &lt;a href=&quot;http://en.wikipedia.org/wiki/Talk_down_aircraft_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;as best I can determine this has never happened in a transport-category aircraft (airliner)&lt;/a&gt; outside of &lt;a href=&quot;https://aviation.stackexchange.com/a/8997/64&quot;&gt;simulations&lt;/a&gt; and similar thought experiments.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-01-13T20:16:47.197" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11684" PostTypeId="2" ParentId="11681" CreationDate="2015-01-13T20:44:25.293" Score="8" Body="&lt;p&gt;The context of your question is a bit unclear, but assuming that you're asking about navigation waypoints in the US then you're probably referring to these terms as &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow&quot;&gt;defined&lt;/a&gt; in the FAA's Pilot/Controller Glossary:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FLY-BY WAYPOINT- A fly-by waypoint requires the use of turn&#xA;  anticipation to avoid overshoot of the next flight segment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;FLY-OVER WAYPOINT- A fly-over waypoint precludes any turn until the&#xA;  waypoint is overflown and is followed by an intercept maneuver of the&#xA;  next flight segment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As per the comments, I have never heard of a &quot;short turn&quot; waypoint and it isn't in the P/CG.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-07T23:29:50.733" LastActivityDate="2015-04-07T23:29:50.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11687" PostTypeId="2" ParentId="11666" CreationDate="2015-01-13T20:51:47.567" Score="4" Body="&lt;p&gt;You are right, lift is concentrated in the forward part of an airfoil, especially at high angle of attack. If you take a single wing and drop it, it will start to rotate around its spanwise axis quickly. This effect is called autorotation (not to be confused with &lt;a href=&quot;http://en.wikipedia.org/wiki/Autorotation&quot; rel=&quot;nofollow noreferrer&quot;&gt;autorotation&lt;/a&gt; in helicopters, though!). Model aircraft pilots should have seen that before: When a model breaks apart in midair, its wing will in many cases autorotate to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an airplane this can be avoided by shifting the center of gravity near the center of lift and by adjusting the lift distribution either with a tail surface, a canard or with wing flaps such that the center of lift is exactly over the center of gravity. Flying wings can do this without a separate tail surface, but need special airfoils which show little change in the location of the center of lift over angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see the pressure acting on an airfoil symbolized by arrows (yes, that is &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;nofollow noreferrer&quot;&gt;XFOIL&lt;/a&gt; at work), and arrows pointing at the airfoil indicate pressure higher than ambient air pressure, and those pointing away from it indicate suction. Their length is proportional to the magnitude of either pressure or suction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Y7JK.png&quot; alt=&quot;Eppler 502 mod with arrows indicating surface pressure&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shows that the forces in the forward part of the airfoil are more intense than those in the rear part. The aerodynamic forces which depend on the angle of attack are focused at the quarter chord point, and without added balancing masses of a fuselage and engines, will be forward of the wing's center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this is strictly true only as long as we have no flow separation. Once rotation starts, separation is unavoidable above the maximum angle of attack. However, inertia will keep the wing spinning until the trailing edge points forward and a similar pressure distribution develops. This gives the rotation another push and keeps the wing spinning over a full revolution, and the whole process starts over.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T20:17:14.223" LastActivityDate="2015-05-07T20:17:14.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11688" PostTypeId="2" ParentId="11627" CreationDate="2015-01-13T20:58:21.167" Score="2" Body="&lt;p&gt;In the USA, there is a &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/25.1457#a_3&quot; rel=&quot;nofollow&quot;&gt;legal requirement&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) The recorder container must be located and mounted to minimize the probability of rupture of the container as a result of crash impact and consequent heat damage to the recorder from fire.&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) Except as provided in paragraph (e)(2) of this section, &lt;strong&gt;the recorder container must be located as far aft as practicable&lt;/strong&gt;, but need not be outside of the pressurized compartment, and may not be located where aft-mounted engines may crush the container during impact.&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) If two separate combination digital flight data recorder and cockpit voice recorder units are installed instead of one cockpit voice recorder and one digital flight data recorder, the combination unit that is installed to comply with the cockpit voice recorder requirements may be located near the cockpit.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-01-13T21:03:44.560" LastActivityDate="2015-01-13T21:03:44.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11689" PostTypeId="1" CreationDate="2015-01-14T00:34:07.263" Score="6" ViewCount="1344" Body="&lt;p&gt;As full-scale aircraft or as models / UAVs / drones?  Is anyone working on making these real or are they fundamentally flawed designs, or needing new materials to be invented?&lt;/p&gt;&#xA;" OwnerUserId="6812" LastActivityDate="2015-01-14T14:24:04.003" Title="Are the military tilted-thrust aircraft in the film Avatar feasible?" Tags="&lt;aircraft-design&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11690" PostTypeId="2" ParentId="11689" CreationDate="2015-01-14T00:57:26.290" Score="5" Body="&lt;p&gt;I presume you're talking about the fictional &lt;a href=&quot;http://james-camerons-avatar.wikia.com/wiki/Aerospatiale_SA-2_Samson&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerospatiale SA-2 Samson&lt;/a&gt;. From that page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ducted fan VTOL aircraft have been flown since at least the 1960s. A notable example was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_X-22&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bell X-22&lt;/a&gt;, a quad-ducted fan experimental aircraft built for the US military. It has no relation to the later V-22 Osprey tiltrotor. Though successful, no military aircraft since have used that technology. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Bell X-22 looked like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/22LTs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which has similar overall characteristics to the SA-2 depictions.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-01-14T00:57:26.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11691" PostTypeId="1" AcceptedAnswerId="11700" CreationDate="2015-01-14T01:04:29.893" Score="10" ViewCount="4000" Body="&lt;p&gt;In June 2014, a &lt;a href=&quot;http://avherald.com/h?article=476566da&quot;&gt;PIA airplane was targeted&lt;/a&gt; by machine gun fire while landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder what would had happened if the fuel tanks were hit? An explosion, perhaps?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in &lt;a href=&quot;http://en.wikipedia.org/wiki/MythBusters_(2005_season)#Car_Capers_.E2.80.93_Exploding_Gas_Tank&quot;&gt;an episode of Myth Busters&lt;/a&gt;, they did shot at a gasoline tank and found out it didn't explode. No ignition temperature was reached they said.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what would be the worst case scenario if a bullet hits the fuel tank on an airplane?&lt;/p&gt;&#xA;" OwnerUserId="6850" LastEditorUserId="65" LastEditDate="2015-01-14T14:28:04.630" LastActivityDate="2015-08-18T18:42:45.973" Title="What happens if fuel tanks are hit by gunfire?" Tags="&lt;safety&gt;&lt;jet&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11692" PostTypeId="1" CreationDate="2015-01-14T02:44:20.660" Score="4" ViewCount="1637" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;nofollow&quot;&gt;F-35&lt;/a&gt; uses lift fan which can create 20,000 lbs (9 tonnes) of lift in a small compact platform. I can see three or four of such lift fans that could lift a heavier plane and is seems better than a helicopter because it can travel at higher speeds.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;So what are the pros and cons of each design?&lt;/li&gt;&#xA;&lt;li&gt;Which one is more efficient in lifting, lift fan or rotate wing?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="19" LastEditDate="2017-03-17T08:50:44.387" LastActivityDate="2017-03-17T08:50:44.387" Title="What are the pros and cons of a lift fan versus a helicopter?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11693" PostTypeId="2" ParentId="11666" CreationDate="2015-01-14T03:07:42.957" Score="12" Body="&lt;p&gt;It does rotate. In fact, in aerodynamics, this rotation force has a name: &lt;a href=&quot;http://en.wikipedia.org/wiki/Pitching_moment&quot; rel=&quot;noreferrer&quot;&gt;pitching moment&lt;/a&gt;. Pitching moment changes depending on the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airfoils can be designed with almost any pitching moment and still generate lift, from positive (trailing edge rotates upwards as you describe), to zero (no rotation) to negative (trailing edge rotates downwards). In general, high lift airfoils have positive pitching moment (because, as you noticed, downwash caused by the Coanda effect increases lift). But zero and negative pitching moment airfoils are useful for tailless and flying wing aircraft. Helicopter blades are long, narrow and flexible so must use zero pitching moment airfoils to prevent them twisting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use an airfoil with a positive pitching moment you need something to counter the rotation. For most aircraft the solution is the horizontal stabilizer (the tail). An alternative solution is the canard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For chevron shaped (V-shaped) flying wings and tailless planes the solution is to twist the wing (in regular planes it's called washout but flying wing designers call it &quot;twist&quot;). The twist causes the wing tips to have less angle of attack (sometimes negative) so that the overall rotation force for the entire aircraft is zero.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastEditorUserId="3386" LastEditDate="2015-01-14T15:08:05.430" LastActivityDate="2015-01-14T15:08:05.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11694" PostTypeId="1" AcceptedAnswerId="11695" CreationDate="2015-01-14T05:21:04.653" Score="15" ViewCount="10456" Body="&lt;p&gt;I know there are some amphibious planes which can land on both water and land but how different is the their landing in comparison to that of a normal small aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if seaplanes needs to go into some marsh, will that work for them?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="755" LastEditDate="2015-01-14T16:19:30.837" LastActivityDate="2015-06-22T12:15:28.693" Title="Can seaplanes land on normal airfields or in a marsh or muddy area?" Tags="&lt;landing&gt;&lt;seaplane&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11695" PostTypeId="2" ParentId="11694" CreationDate="2015-01-14T05:55:28.567" Score="12" Body="&lt;p&gt;A pure seaplane cannot land on a normal (land) airfield: The hull or floats would be badly damaged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;em&gt;amphibious&lt;/em&gt; aircraft can land on both water or a normal airfield (pavement, grass, gravel, etc.), because it has both wheels and floats, but with amphibious aircraft you're either operating as a seaplane (on water) or a landplane (on solid ground), and you would follow procedures appropriate to the type of operation you're conducting.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As I understand it amphibious aircraft would not be suited to landing in a &quot;marsh&quot; or &quot;swamp&quot;: The water and mud would render the wheels ineffective (and possibly dangerous: If the wheels dig in to the mud the aircraft could flip over), and the dirt/land portions of the area would damage or destroy the floats/hull.&lt;br&gt;&#xA;It may be &lt;em&gt;possible&lt;/em&gt; to put the aircraft down in such an area, but it would be very unsafe, bordering on &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/f4c347a942ecd9dd852566cf00612726!OpenDocument&quot;&gt;reckless&lt;/a&gt;, to do so in a non-emergency situation.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-14T05:55:28.567" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11696" PostTypeId="1" CreationDate="2015-01-14T06:32:04.010" Score="1" ViewCount="960" Body="&lt;p&gt;We have the Airborne Pulse Doppler radar for weather predictions which are I think same as in the A350s and also in fighter jets so, what is the response time of these radars?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if a fighter jet is travelling greater than Mach 1, how much will be the response time of the weather radar and how the response time will affect w.r.t to the speed of the plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Response time means how frequently the data coming from the Radar is getting updated? Like in case of Flight Radars etc, the normal response time or update time for the data varies from 40ms to 100ms.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2018-04-26T01:16:03.160" LastActivityDate="2018-04-26T01:16:03.160" Title="What is the response time of Pulse Doppler Radar?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11697" PostTypeId="2" ParentId="11694" CreationDate="2015-01-14T07:07:33.363" Score="30" Body="&lt;p&gt;Back in the early 1970s I belonged to a Civil Air Patrol (CAP) squadron that had a J-3 cub with an 85 horse engine on it. During the summer we would operate it on floats, during the winter on wheels. At the end of summer, we would land it on the grass alongside the runway at the Springfield, OR airport (no longer there, &lt;a href=&quot;http://www.airfields-freeman.com/OR/Airfields_OR_SW.htm#springfield&quot;&gt;it's a big Walmart now&lt;/a&gt;) and replace the floats with wheels. In late spring, we'd replace the wheels with floats and take off from the grass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The joke was that for takeoff you were supposed to line up all the cadets and have them pee in unison along the path the floats would take to aid in the takeoff. Actually, that wasn't necessary since western Oregon gets a lot of rain. Even with wet grass though, for the takeoff we'd get the initial movement by pushing, and we were always careful to ensure that the grass had nothing on the takeoff path that would damage the floats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the floats on, you could fly when the airspeed said 40 mph (yes, it was indicated in mph) which is about 35 knots. You could generally count on at least 5 knots of wind right down the runway when it was raining, so at 30 knots across the grass you were good to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can go to YouTube and search &quot;floatplane landings on grass&quot; to see some examples of landing on grass. &quot;Floatplane takeoffs on grass&quot; will show some takeoffs, but a quick look showed using a dolly, which I think we did once or twice before my time with the group but then figured it was easier to just use the grass.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1696" LastEditDate="2015-01-14T18:42:38.520" LastActivityDate="2015-01-14T18:42:38.520" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11698" PostTypeId="2" ParentId="11694" CreationDate="2015-01-14T07:22:26.263" Score="11" Body="&lt;p&gt;Seaplanes can land on land (pun intended) if the ground has a soft cover. This could be snow, tall grass and landing in a wet peat bog is also possible. However, any solid object close to the surface (logs, stones) will damage the hull.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historic cases are the landings of &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Do_J#Pioneering_flights&quot; rel=&quot;noreferrer&quot;&gt;Amundsen with a Dornier Wal&lt;/a&gt; on arctic ice or the landing of &lt;a href=&quot;http://blog.nasm.si.edu/aviation/wolfgang-von-gronau-and-his-greenland-whales/&quot; rel=&quot;noreferrer&quot;&gt;Gronau's Wal&lt;/a&gt; when it was transferred to the Museum in Munich (actually, this was the same aircraft). It was landed in winter on a snow-covered meadow close to the Isar river in central Munich.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was in no small part possible due to the flat hull shape of Dornier flying boats. They were optimized with water tunnel studies for the heavy and inefficient engines of their time. &lt;a href=&quot;http://en.wikipedia.org/wiki/Beriev_Be-200&quot; rel=&quot;noreferrer&quot;&gt;Modern hulls&lt;/a&gt; have a keeled shape, where the bottom is v-shaped to reduce the load factor when &lt;a href=&quot;http://en.wikipedia.org/wiki/Planing_(boat)&quot; rel=&quot;noreferrer&quot;&gt;planing&lt;/a&gt; in rough sea. Landing such a seaplane on land needs more snow and should not be attempted on grass.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-22T12:15:28.693" LastActivityDate="2015-06-22T12:15:28.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11699" PostTypeId="2" ParentId="11692" CreationDate="2015-01-14T07:36:49.203" Score="9" Body="&lt;p&gt;To answer your second question first:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, it is always better to accelerate a big amount of air a little than a small amount a lot. Therefore, the helicopter rotor is much more efficient when creating lift, similar to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;propeller&lt;/a&gt; which is &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/rotary-engine-planes-in-commercial-flights/10037#10037&quot;&gt;more efficient than a jet&lt;/a&gt;. In the same way, more wing span reduces induced drag since more air can be used for &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;lift creation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantages of a lift fan are mainly due to its compact size:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Low mass, low inertias&lt;/li&gt;&#xA;&lt;li&gt;Compact size, therefore easy to tuck away for fast flight&lt;/li&gt;&#xA;&lt;li&gt;Low torque for a given amount of lift&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and the disavantages stem from the same source:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Low efficiency&lt;/li&gt;&#xA;&lt;li&gt;High exit speed, so beware of the blast.&lt;/li&gt;&#xA;&lt;li&gt;No &lt;a href=&quot;http://en.wikipedia.org/wiki/Autorotation&quot; rel=&quot;nofollow noreferrer&quot;&gt;autorotation&lt;/a&gt; possible when the engine fails.&lt;/li&gt;&#xA;&lt;li&gt;Lift acts at the center of the fan, so you need additional jets for pitch and roll control. A helicopter can shift the center of lift away from the rotor axis (within limits) by using cyclic changes to the angle of attack of the single rotor blades.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-01-14T16:35:22.167" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11700" PostTypeId="2" ParentId="11691" CreationDate="2015-01-14T07:48:16.073" Score="16" Body="&lt;p&gt;The worst case depends on the kind of bullet. If a tracer bullet hits an empty fuel tank which contains a mixture of air and fuel vapor, an explosion will follow. A regular bullet will just punch a hole into the tank, but will not be hot enough to start combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On today's airliners and combat aircraft the fuel tanks will be filled with an inert gas, so there is not enough oxidizer present to support combustion. Even the tracer bullet will have no effect. Now the tank will have a hole, however, and if it is below the fuel level, some of it will leak out and could be ignited by a hot object. This will be the main source of fire, but will not lead to an explosion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since WWII, most military aircraft used &lt;a href=&quot;http://en.wikipedia.org/wiki/Self-sealing_fuel_tank&quot; rel=&quot;noreferrer&quot;&gt;self-sealing tanks&lt;/a&gt;, to much the same effect. This was a double-skinned tank with a rubber middle layer which would swell when wetted with fuel and close the hole.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-18T18:42:45.973" LastActivityDate="2015-08-18T18:42:45.973" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11702" PostTypeId="2" ParentId="11689" CreationDate="2015-01-14T10:27:06.223" Score="2" Body="&lt;p&gt;They are feasible in as much as the atmosphere on &quot;Pandora&quot; is thicker and the force of gravity is lighter. C.f. &lt;a href=&quot;http://james-camerons-avatar.wikia.com/wiki/Pandora&quot; rel=&quot;nofollow&quot;&gt;Avatar Wiki&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows for both large winged reptiles (?) and smaller tiltrotors than are possible on our current earth.&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; There is evidence that our atmosphere was more oxygen-rich in the geologic past and may have been thicker, allowing for similarly large reptiles. &lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="65" LastEditDate="2015-01-14T14:24:04.003" LastActivityDate="2015-01-14T14:24:04.003" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11703" PostTypeId="2" ParentId="11689" CreationDate="2015-01-14T10:44:39.290" Score="1" Body="&lt;p&gt;Yes, they are certainly feasible. In fact, one basically exists already: &lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow&quot;&gt;the V-22 Osprey&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main difference being that the V-22 has ailerons for roll control and wings for lift in forward flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power isn't a problem, it's just a multirotor helicopter... think Chinook, on a different axis. And control, for the most part, isn't a major issue.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Differential power to the two motors provides Roll control, similar to a quadcopter&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rotating the rotors slightly forward/back and/or something similar to a cyclic on a conventional helicopter allows (similar to the Osprey tiltrotor):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Forward/reverse flight (if tilted together)&lt;/li&gt;&#xA;&lt;li&gt;Yaw control (if tilted in opposing directions... think tank tracks&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If attached in away that they can be angled up/down, pivoting on the attachment to the fuselage, the vehicle can &quot;strafe&quot; (ie lateral sideways movement)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pitch when in forward/reverse flight is provided by the tail stabilisers. In the hover it could presumably be controlled to some extent by means similar to a conventional helicopter's cyclic, shifting weight, or by an additional small rotor near the tail, if you didn't want to be 100% true to the movie model&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://youtu.be/U0OmZA2vQ14&quot; rel=&quot;nofollow&quot;&gt;Here's a working model&lt;/a&gt;, for example. I don't believe there are any full size models, but the Osprey is &quot;close enough&quot; to prove the concept.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="65" LastEditDate="2015-01-14T14:18:10.680" LastActivityDate="2015-01-14T14:18:10.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11704" PostTypeId="1" AcceptedAnswerId="11706" CreationDate="2015-01-14T12:30:23.417" Score="10" ViewCount="2783" Body="&lt;p&gt;I know that the sweep will allow the flight to fly at higher speed because the perpendicular air flow speed (over wing) is less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I didn't understand why there is trailing edge sweep? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can have a swept leading edge and unswept trailing edge to produce elliptical lift distribution. Also, unswept trailing edge will help to improve flap effectiveness, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone please explain this to me. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance&lt;/p&gt;&#xA;" OwnerUserId="6857" LastEditorUserId="167" LastEditDate="2015-01-16T02:57:54.303" LastActivityDate="2015-01-16T02:57:54.303" Title="What is the aerodynamic benefit of trailing edge sweep?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11705" PostTypeId="2" ParentId="11704" CreationDate="2015-01-14T13:16:25.550" Score="3" Body="&lt;p&gt;The trailing edge sweep is not a design variable, it mainly follows from the quarter cord sweep (to control the effective Mach number) and the taper-ratio (or actually planform, to ensure elliptical lift).&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-01-14T13:16:25.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11706" PostTypeId="2" ParentId="11704" CreationDate="2015-01-14T13:16:36.123" Score="7" Body="&lt;p&gt;Both leading and trailing edge sweep help to reduce compressibility effects. For simple estimates, quarter chord sweep is used. This is more influenced by the leading edge, but the trailing edge is still involved with 25% of the total value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at the particular influence of trailing edge sweep, it is mostly found in the effectiveness of flaps and ailerons. Their effectiveness is proportional to the cosine of hinge line sweep. However, flaps at the end of a long wing chord will create a high pitching moment, requiring a big tail. Most delta wings use simpler, less effective flaps with less moment change.&#xA;In supersonic aircraft trailing edge sweep helps to reduce sonic boom intensity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, trailing edge sweep is mostly an outcome of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;design process&lt;/a&gt;, similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing/8797#8797&quot;&gt;wing chord&lt;/a&gt;. The structural engineer will want to have a deep root airfoil in order to have enough wing height for a stiff spar or the landing gear without increasing relative thickness too much, and the aerodynamicist wants to reduce wetted area, since it will create friction drag and increase wing mass. In the end, all have to agree to a compromise.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-01-15T21:44:50.863" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11707" PostTypeId="2" ParentId="11591" CreationDate="2015-01-14T14:48:56.653" Score="8" Body="&lt;p&gt;I believe that Approach is the correct phraseology. First, have a look at these definitions from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;APPROACH CONTROL SERVICE- Air traffic control service provided by an&#xA;  approach control facility for arriving and departing VFR/IFR aircraft&#xA;  &lt;strong&gt;and, on occasion, en route aircraft&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DEPARTURE CONTROL- A function of an approach control facility&#xA;  providing air traffic control service for &lt;strong&gt;departing&lt;/strong&gt; IFR and, under&#xA;  certain conditions, VFR aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0502.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 5-2-7&lt;/a&gt; also says that Departure Control is for departing aircraft only:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Departure Control is an approach control function responsible for&#xA;  ensuring separation between departures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So according to the FAA's definitions, only Approach Control has any responsibility for en route traffic, which includes the scenario you described in your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, note that the VFR sectional chart always requests en route pilots to contact Approach, not Departure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PB3Uf.png&quot; alt=&quot;VFR sectional - contact Approach&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FWIW, I was also taught that &quot;Departure&quot; is used only when actually departing a field and that all 'pop-up' communication with the TRACON should use &quot;Approach&quot;; this is in line with the information above.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-07T23:30:10.887" LastActivityDate="2015-04-07T23:30:10.887" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11708" PostTypeId="1" CreationDate="2015-01-14T14:49:16.350" Score="10" ViewCount="4185" Body="&lt;p&gt;I know what vortex generators (VGs) do. My question is: &lt;strong&gt;How come some aircraft have VGs on both sides of the engine, whereas other aircraft have them on the inside only?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in this picture of Boeing 737, a vortex generator is only on the inside of the engine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9VlmV.jpg&quot; alt=&quot;Boeing 737&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary, the Airbus A319 has them on both sides:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KUH5f.jpg&quot; alt=&quot;A319&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="22726" LastEditDate="2019-08-26T01:16:30.030" LastActivityDate="2020-01-01T21:52:54.243" Title="How does the position of vortex generators on engine cowlings affect flight?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;vortex-generators&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="11709" PostTypeId="1" CreationDate="2015-01-14T15:04:41.110" Score="19" ViewCount="19730" Body="&lt;p&gt;I know that airplanes use rudder to turn, and use elevator for nose up and down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do helicopters change their altitude and how do they make turns?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="65" LastEditDate="2015-01-14T15:08:31.827" LastActivityDate="2018-03-15T06:19:55.277" Title="How do helicopters turn using rotor?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11710" PostTypeId="2" ParentId="11709" CreationDate="2015-01-14T15:20:06.027" Score="5" Body="&lt;p&gt;There are three controls in a helicopter:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cyclic stick (this cyclically changes the pitch of the blades, creating different amounts of lift at different points of the cycle)&lt;/li&gt;&#xA;&lt;li&gt;Collective lever (this determines the force generated by the rotor)&lt;/li&gt;&#xA;&lt;li&gt;The anti-torque pedals (they control the tail-rotor)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This picture shows the result of moving the cyclic. As you can see, the whole rotor is turned, causing the helicopter to move in a certain direction, as shown in this image by &lt;a href=&quot;http://avstop.com/ac/basichelicopterhandbook/ch4.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AVstop&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/SofTw.jpg&quot; alt=&quot;Helicopter handbook&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The collective determines the amount force generated by the main rotor&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The anti-torque rotor is used to rotate the helicopter, as shown here, obtained from &lt;a href=&quot;http://www.flightsimbooks.com/gunship/03_4_The_Anti-Torque_Rotor.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gunschip Academy&lt;/a&gt;:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/RCKDC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main rotor will induce a torque on the cabin, making it spin. A force is needed to prevent this spinning. The tail-rotor provides this force, keeping the helicopter-cabin straight.&#xA;However, if we want the cabin to rotate, we can adjust the blade pitch of the tail-rotor. This will change the force delivered by the tail-rotor. The imbalance in moments will then rotate the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted here, that all the movements are strongly coupled. Any input will always have additional side-effects, which need to be counteracted.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-01-15T14:09:49.683" LastActivityDate="2015-01-15T14:09:49.683" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11711" PostTypeId="2" ParentId="11709" CreationDate="2015-01-14T15:47:00.970" Score="2" Body="&lt;p&gt;&lt;strong&gt;Turn Control&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to effect a turn a lateral acceleration (horizontally to the left or right relative to the direction of the vehicles motion) is needed. Consider a bicycle leaning towards the center of a turn.&#xA;In an aircraft primarily two things happen.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The ailerons are used to bank the aircraft towards the center of the turn in order to tilt the lift vector.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Particularly in slow aircraft the rudder is used to adapt the rotation of the aircraft around the vertical axis to the changing direction. This ensures that no sideslip occurs, i.e. that the aircraft always points exactly in the direction of flight (in reference to the air).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Once a helicopter has significant forward speed the same principles apply. Via the stick the cyclic rotor control is used to bank the helicopter (slightly) towards the turn center. The torque pedals are then used to coordinate the turn (sync the change in direction with the turn speed of the helicopter).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Altitude Control&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to change the altitude the flight path needs to be increased or decreased. Also two things need to happen.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The flight path needs to be changed via a short vertical acceleration (to bend it).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Then the aircraft needs to be stabilized / trimmed to maintain this path.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For fixed wing aircraft there are actually different techniques to do this.&#xA;The most intuitive is to change the pitch of the aircraft via the elevator. Upon descending or climbing the thrust (engine setting) needs to be adapted. (A glider will adapt its speed accordingly).&#xA;Another technique with classical fixed wing aircraft is to reduce (sink) or increase (climb) the engine power / thrust level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters make use of their direct control of the lift via the collective control. (Subsequently this results in a change of rotor torque which needs to be compensated via the pedals and the engine settings.) &lt;/p&gt;&#xA;" OwnerUserId="3964" LastEditorUserId="3964" LastEditDate="2015-01-14T15:59:18.420" LastActivityDate="2015-01-14T15:59:18.420" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="11712" PostTypeId="2" ParentId="11708" CreationDate="2015-01-14T15:57:03.217" Score="10" Body="&lt;p&gt;The vortex generator helps only at high angle of attack by energizing the airflow between nacelle and wing. During cruise it will create additional drag without much benefit, especially if the nacelle-wing-combination has been designed well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in the landing configuration it can help to lower minimum airspeed by several knots and make shorter landings possible. Now the aircraft maker has to decide what is worth more: Shorter field length, or slightly less cruise drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 737 started life with a much more slender engine and had a very short landing gear when more fuel-efficient engines came to market. A lot of brain- and computing-power was needed to develop its pear-shaped engine nacelles, and the vortex generator became an essential element of it. At the inside location it helps to keep the flow path between wing, fuselage and nacelle clear of separated air, whereas on the outside a second generator would make only a minor difference.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-14T20:01:31.143" LastActivityDate="2015-01-14T20:01:31.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11713" PostTypeId="1" AcceptedAnswerId="11721" CreationDate="2015-01-14T15:58:55.483" Score="8" ViewCount="1530" Body="&lt;p&gt;If one were to design an aircraft to have neutral longitudinal stability would this reduce the required horizontal stabiliser surface and hence trim drag?&lt;/p&gt;&#xA;" OwnerUserId="6859" LastActivityDate="2020-04-09T16:48:13.253" Title="Can the design for neutral stability reduce trim drag?" Tags="&lt;drag&gt;&lt;trim&gt;&lt;stability&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11714" PostTypeId="1" AcceptedAnswerId="11718" CreationDate="2015-01-14T16:20:11.547" Score="15" ViewCount="5252" Body="&lt;p&gt;&lt;strong&gt;Premises&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For usual communications between pilots and ATC, a specific phraseology is followed.&lt;/li&gt;&#xA;&lt;li&gt;In case of an an unexpected event (e.g. a sick passenger), flight attendants and pilots can communicate through intercom.&lt;/li&gt;&#xA;&lt;li&gt;Pilots (particularly the captain) can speak to all people in the cabin (including flight attendants) through the public address system.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do the communications made between the cockpit and the cabin (thanks to the public address system) follow a specific phraseology to deliver information to flight attendants?&lt;/li&gt;&#xA;&lt;li&gt;Are there some messages following a specific phraseology that trigger a reaction among the flight attendants (e.g. preparation for flying across turbulence), but passenger may think the message is address to them?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I think of the coordination of the preparation of the cabin for the different flight phases (taxiing, taking off,...) or indication of the strength of turbulence (implicating the flight attendant may not begin to move carts along the cabin).&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3386" LastEditDate="2017-05-18T22:03:09.337" LastActivityDate="2017-05-18T22:03:09.337" Title="Are the communications between captain and flight attendants standardized?" Tags="&lt;airliner&gt;&lt;pilots&gt;&lt;airline-pilot&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11715" PostTypeId="2" ParentId="11675" CreationDate="2015-01-14T16:26:50.200" Score="8" Body="&lt;p&gt;Aerodynamic noise has many sources. It is not white noise, because some frequencies are dominant. Generally it happens when flows of different speed collide, or when a standing wave develops in a cavity. Common noise sources are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Uncovered openings, like vent holes or control surface gaps. Like when you blow across the top of an open bottle, they produce a howling sound with a dominant frequency that depends on flow speed and opening size.&lt;/li&gt;&#xA;&lt;li&gt;Tollmien-Schlichting waves in the boundary layer. These frequencies change with speed and their location along the flow path, and generally are responsible for most of the hissing sound of gliders.&lt;/li&gt;&#xA;&lt;li&gt;Separated flow, which produces alternating separations behind blunt bodies. Here the main frequency is that of the Karman vortex street that forms behind them. It can be calculated if the &lt;a href=&quot;http://en.wikipedia.org/wiki/Strouhal_number&quot;&gt;Strouhal number&lt;/a&gt; Sr of the flow is known. This is the equation for the main frequency $f$ of a bracing wire with the diameter $d$: $$f = Sr \cdot \frac{v}{d}$$&#xA;Here $v$ is the airspeed, and for bracing wires Sr is normally 0.2. Bracing wires (or a blunt trailing edge, for that purpose) produce a characteristic whistling sound.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As you said, the landing configuration makes most noise. In addition to the factors above, you now have&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Extended flaps, mostly with gaps between them which show high local flow speed. This local high-speed flow is very noisy.&lt;/li&gt;&#xA;&lt;li&gt;Many more blunt objects sticking out of the airframe: Landing gears, gear covers or landing lights. The particular noise of landing gears was once tested with a &lt;a href=&quot;http://www.akaflieg-braunschweig.de/prototypen/sb10/&quot;&gt;high-performance glider&lt;/a&gt; which had styrofoam gears fitted under the wings. They broke off when it had to land, but yielded valuable data when compared to the noise of the clean glider. Sorry, there is no photo of this experiment on the web!&lt;/li&gt;&#xA;&lt;li&gt;The gaping hole of the landing gear well. Especially while the gear is moved, this creates a lot of noise, but even after extension a part of the well is uncovered and adds its noise.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flugl%C3%A4rm-portal.de/laerm-vermeiden/moderne-flugzeuge/oberflaeche-fluegel-fahrwerk/&quot;&gt;Here&lt;/a&gt; is a good overview of different noise sources. It is best read with a good working knowledge of German.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question: The sound is a mixture of hissing and whistling in different frequencies. If you stand close to the Autobahn (best is a section without speed restrictions), the noise of the passing cars is similar, but less intense. At 180 km/h, engine noise starts to vanish in all the aerodynamic and tire noises ...&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-01-14T16:26:50.200" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11716" PostTypeId="2" ParentId="11709" CreationDate="2015-01-14T16:31:13.137" Score="3" Body="&lt;p&gt;Think of a triangle of vectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the rotor disk is exactly level, the thrust from the rotor acts vertically.  If you tilt the rotor, you now have a slightly reduced vertical thrust (the thrust vector) and a horizontal component which will apply a force to the helicopter in the direction of that horizontal component.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As ROIMaison states, the cyclic control tilts the rotor disc as required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please excuse my lousy drawing skills.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Disc level&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CGk4r.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Disk titled&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JCmte.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the vertical component is now reduced (the total thrust is the sum of the vertical and horizontal component), the helicopter will descend slightly since the vertical thrust no longer balances the weight.  Therefore, a small increase in power is required achieved by increasing collective pitch.  The engine then creates more torque which must be balanced with opposite torque from the tail rotor, achieved by moving the opposite pedal forwards.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As in all aircraft changes, there is a primary effect (tilting the disc in the direction of travel) and secondary affects of increased power and increased torque.  This is why flying a helicopter needs adjustment of all three controls together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To climb, you adopt a climbing attitude, by pulling back on the cyclic, which causes the nose to rise.  Because the horizontal component of the total rotor thrust is now reduced (since the disc is now titled forward less), your speed will reduce unless you increase power by increasing the collective pitch which increase the horizontal component.  This will need an input on the pedals to balance the correct torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To descend, you reduce power, which reduces the total rotor thrust.  Since the vertical component no longer opposes the weight, the helicopter will descend.  Since power is reduced, the horizontal component of the thrust is reduced and the helicopter will slow down.  You push forward on the cyclic to increase the horizontal thrust and maintain speed.  Of course, a pedal input is required to counter the reduced torque from the engine.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-14T16:52:41.967" LastActivityDate="2015-01-14T16:52:41.967" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11717" PostTypeId="2" ParentId="11691" CreationDate="2015-01-14T16:49:37.880" Score="18" Body="&lt;p&gt;OK, let me expand my comments about inert gas to Peter Kämpf's answer to an own answer.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Argon or Nitrogen ?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It was asked if Argon is a suitable inert gas. While in principle it is, it is also a rare element and so expensive. A better choice is nitrogen. It makes up 79% of the air and is much cheaper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I found ~50€ for a 50l bottle of nitrogen and ~100€ for argon.&#xA;But one also has to keep in mind that the production capacity for argon is not very high, so if aviation starts to buy large amounts to use it as inert gas, the price would increase soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Argon and nitrogen are gases which can not be liquefied at normal temperatures, so they are stored under pressure in bottles like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Dxwq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are made of steel to  withstand the pressure of up to 200-300 bar (atmospheres). So, a big 50l bottle has a weight of 77kg without filling &lt;a href=&quot;http://www.airliquide.de/loesungen/produkte/gase/lieferformen/cylinder-versorgung.html#.VLbG1h05wWN&quot; rel=&quot;noreferrer&quot;&gt;(sorry, german)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowadays, also civilian aircraft are often equipped with an inert gas system, since &lt;a href=&quot;http://en.wikipedia.org/wiki/TWA_Flight_800&quot; rel=&quot;noreferrer&quot;&gt;the central wing tank of TWA800 exploded most likely due to electrical short circuits&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when it comes to larger aircrafts with larger tanks, gas bottles become a problem: The A380 has a fuel capacity of 325,000 liters. Imagine you want to fill its tanks from the 50l bottles mentioned above. The content of one bottle expands to 10,000-15,000 liters at sea level pressure, so you need 20-32 bottles for the A380. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This bottles have a weight of almost 2.5 tons and need some space. The high pressure is also an issue, and of course, you have to refill the bottles after each flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it's not a good idea to use this system on larger aircrafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was quite sure that I once read that at least small aircrafts like fighters use bottles, but I don't find any evidence. On the other side, a F35 can carry up to 10,000l in its internal tank, so it would also need a 50l bottle. So, I think I misunderstood something.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;CO2 ?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The benefit of CO2 is that it becomes liquid under pressure, You won't need so many bottles and the bottles themselves would be lighter. But &lt;a href=&quot;http://www.twi-global.com/technologies/material-properties/corrosion/co2-corrosion/&quot; rel=&quot;noreferrer&quot;&gt;CO2 may act corrosive&lt;/a&gt; if it finds some drops of water, as it turns to carbonic acid.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Exhaust gas?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A gas that is the product of a fire doesn't burn any more.&#xA;This is indeed used to fill the tank of large ships, but you can not take it from the main engine: Those are diesel engines always working with an excess of air, so the exhaust gas contains oxygen. The ships burn some fuel with a balanced amount of air in a &lt;a href=&quot;http://www.machineryspaces.com/fire-fighting-inert-gas-system.html&quot; rel=&quot;noreferrer&quot;&gt;inert gas generator&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As fans are similar to diesel engines in this context, exhaust gas is no solution. The gas also contains CO2 and water, so may be no good idea in general for aviation.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Halon&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Many older combat aircrafts like the &lt;a href=&quot;http://www.nist.gov/el/fire_research/upload/R9902741.pdf&quot; rel=&quot;noreferrer&quot;&gt;F16 use halon&lt;/a&gt; to extinguish fire, but also to fill the tanks.&#xA;As halon is one of the worst greenhouse gases, its production has been abandoned 1994 and this document describes the search for alternatives working largely the same way:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To explain it in short: Inside a fire, molecules of the burning material break up and connect to oxygen atoms. This connection is what gives the energy we want in our engines and we want not in the tank.&#xA;Halon jumps into the reaction and connects itself to the open ends. The reaction between oxygen and the material, which gives the energy, can not take place any more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is said that about 6% of halon in air is enough to extinguish fire, 10% and more can be survived, if exposure time is not too long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Halon was not used as inert gas, but it was injected into the tanks shortly before a fight was expected&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;On-Board Inert Gas Generation System(OBIGGS)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Today's solution is to use a On-Board Inert Gas Generation System(OBIGGS) &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010092198.pdf&quot; rel=&quot;noreferrer&quot;&gt;developed by NASA/Boeing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It uses some kind of membrane which can be passed by nitrogen more easily than by oxygen. Bleed air is lead to this membrane with some pressure. The oxygen is kept back and you get air with a significantly smaller fraction of oxygen behind the membrane. There are &lt;a href=&quot;http://www.airliquideadvancedtechnologies.com/en/our-offer/aeronautics/obiggs/obiggs-for-aircraft.html&quot; rel=&quot;noreferrer&quot;&gt;devices on the marked&lt;/a&gt; which produce 2lb/min with up to 1% remaining oxygen&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The goal is to have not more than 9-12% in the tank, see the link to NASA above.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;By the way: In WW I, Germany sent hydrogen filled airships to England. One could guess just shooting at them would take them down, but the holes were too small to cause a reasonable loss of hydrogen. And unless the bullets made sparks when hitting some steel in the ships, they also did not set the ships on fire. It turned out that firing standard munition at airships was quite useless. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution was to use phosphor based tracker munition which set the hydrogen streaming out of the leaks from the other bullets on fire.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="1961" LastEditDate="2015-01-14T21:18:07.857" LastActivityDate="2015-01-14T21:18:07.857" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11718" PostTypeId="2" ParentId="11714" CreationDate="2015-01-14T19:09:08.027" Score="16" Body="&lt;p&gt;Been waiting for an answer but none coming so - guesswork and experience, since no citations or direct knowledge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a mixture of both.  Often, cockpit to cabin communication is one to one.  Rather than use the cabin address, the crew will call a specific station for example, the rear galley.  So if the captain wants a coffee, they will not use the cabin address, nor is there any need for a formalised language.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Please may I have a cup of coffee?&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Other comms may be most effective using cabin address but still not needing a formalised language, for example.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Cabin crew, please take your seats.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This call would only happen after the passengers are belted in, since you are already in turbulence and the cabin crew don't need a formal instruction to buckle up.  In my experience, the initial call to warn of turbulence ahead is made one to one to a specific station, usually the purser or senior cabin crew member.  That person will then instruct the rest of the crew. The fact that the crew has been asked to sit, means that the carts will be stowed and the cabin prepared.  It's just a part of their routine.  In the case of unexpected heavy or severe turbulence, the crew probably do not need a call, since they know about it at the same moment the cockpit crew know but, a specific instruction might be given to indicate urgency.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Cabin crew, please take your seats immediately.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Some comms are most effective with an address and a formal command, for example.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Cabin crew, doors to automatic and cross-check.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This is a safety critical procedure and is therefore specifically addressed (&quot;cabin crew&quot;) and a precise instruction (&quot;doors to automatic&quot;, &quot;cross check&quot;).  It was doors to automatic, not manual, and check the opposite door to make sure the person responsible for that door has done it, and done it correctly.  Note that this particular command is normally given by the purser or senior member, and not from the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a call to &quot;all stations&quot; which will call all the station phones and whichever crew member picks up will deal with the comms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, the precise wording of instructions is not regulated but is part of company SOPs and check lists.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-14T22:55:25.410" LastActivityDate="2015-01-14T22:55:25.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11719" PostTypeId="2" ParentId="11709" CreationDate="2015-01-14T19:51:03.257" Score="29" Body="&lt;p&gt;Airplanes do not use their rudder to turn; they do it by &lt;em&gt;banking into the direction of the desired turn, then the wings &quot;lift&quot; the plane in that direction.&lt;/em&gt;  The rudder is only used to maintain lateral trim, so that the airflow doesn't impinge on the side of the fuselage and drag is minimized.  To initiate a turn, the pilot uses the stick or yoke to actuate the ailerons on the wingtips, causing the wing on the inside radius of the turn to go down and the wing on the outside radius of the turn to go up.  A slight back-pressure of the stick or yoke raises the nose, causing a &quot;climb&quot; to be initiated, but since the plane is banked toward the center of a circle, the &quot;climb&quot; doesn't cause a change in altitude, instead it causes the plane to fly a circular path.  Small, simultaneous changes in engine power and rudder deflection are needed in order to maintain proper trim and constant altitude in what is called a &quot;coordinated turn&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters turn in a manner analogous to that of an airplane.  In forward flight, the cyclic stick (between the pilot's legs) is pushed slightly in the direction of the desired turn, causing the rotor disc to tilt, just as the wings of an airplane are tilted in a banked turn.  The collective lever and throttle (at the pilot's left side) are adjusted as needed to maintain altitude and the rudder pedals are adjusted to maintain a coordinated turn.  Since the fuselage of a helicopter is suspended from the rotor hub like a pendulum, as the helicopter enters the turn, the fuselage tends to be flung outward, so it banks, just like the fuselage of the airplane that is rigidly connected to its wings.  (In a hover, with no forward airspeed, a helicopter can turn in any direction with the rudder pedals alone, something an airplane cannot do.  In this special case the fuselage remains level.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To change altitude, it is necessary to add power to climb or reduce power to descend.  This is true of any heavier-than-air aircraft, as, for a constant velocity, increasing altitude implies increasing potential energy and decreasing altitude implies reducing potential energy.  In helicopters in forward flight, a climb is accomplished by first pulling back slightly on the cyclic stick to raise the nose and establish a climb attitude, then raising the collective lever and twisting the throttle grip on the collective lever to maintain constant rotor speed.  As the collective is raised, the pitch of the main rotor blades increases, giving them more &quot;bite&quot; on the air and, therefore, more lift.  A skilled helicopter pilot will perform these actions in a coordinated manner, such that everything appears to happen simultaneously.  In the special case of a hover, a helicopter can climb and descend with the rotor disk in a constant horizontal attitude.  As described above, the collective lever is raised and power is increased with the throttle to put more energy into the system, raising the aircraft; to descend the collective lever is lowered and power is decreased with the throttle.  Directional control in a hover is maintained entirely with the pedals; if the helicopter is the most common type with an anti-torque tail rotor, moving the rudder pedals requires the throttle to be increased or decreased slightly to compensate for the varying power consumed by the tail rotor and to maintain constant altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If this sounds complicated to you, you're right.  Rotary wing flight is considerably more difficult than fixed wing flight, and it took decades longer to perfect helicopters after fixed wing aircraft had taken to the skies.)&lt;/p&gt;&#xA;" OwnerUserId="6861" LastActivityDate="2015-01-14T19:51:03.257" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="11720" PostTypeId="1" AcceptedAnswerId="11722" CreationDate="2015-01-14T20:16:56.627" Score="8" ViewCount="2569" Body="&lt;p&gt;It seems like AgustaWestland might finally get certification for the AW609 in the next couple of years.  Let's say I buy one to transport people to the offshore oil platforms that I hypothetically own.  I'm going to need pilots with a commercial powered-lift rating or possibly an ATP powered-lift, depending on how the aircraft ends up being certified.  Where am I going to find these pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can tell, the only people who current have FAA powered-lift ratings either converted military ratings from the V-22 Osprey, or are civilian test pilots who worked on the V-22 or AW609 programs.  I guess I could try to hire these pilots, but I will be competing with every other AW609 operator.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a way for rotorcraft pilots to transition to powered-lift?  Is there any way, currently, for a civilian pilot to go from no ratings to commercial powered-lift without getting non-powered-lift ratings first?&lt;/p&gt;&#xA;" OwnerUserId="2696" LastEditorUserId="62" LastEditDate="2017-01-03T18:02:53.017" LastActivityDate="2017-01-03T18:02:53.017" Title="How would you get certified for the AgustaWestland AW609 as a rotorcraft pilot or without any previous certification?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;aircraft-certification&gt;&lt;powered-lift&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11721" PostTypeId="2" ParentId="11713" CreationDate="2015-01-14T22:10:01.703" Score="11" Body="&lt;p&gt;Terminology first: Trim drag is the drag component added by adjusting the incidence of the horizontal tail rsp. the deflection angle of the elevator for trim. The increased parasitic drag of a larger tail surface itself is already part of the aircraft's zero-lift drag.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Sizing criteria for tail surfaces&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The horizontal stabilizer surface must be dimensioned with these criteria in mind:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Sufficient static longitudinal stability. To achieve this, the tail volume (tail area times lever arm) must be high enough. Use similar aircraft and copy what has been found to work well.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sufficient pitch damping. This is driven by tail size times the square of the tail lever arm.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sufficient control power at the most forward cg location over the whole speed range.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Sufficient control power at the most forward cg location over all load factors (including pitch damping effects).&lt;/li&gt;&#xA;&lt;li&gt;Sufficient control power when flaring in ground effect (which reduces elevator effectivity)&lt;/li&gt;&#xA;&lt;li&gt;For T-tail configurations: Sufficient control power over all sideslip angles. Sideslip produces a strong pitch-down moment in T-tail configurations.&lt;/li&gt;&#xA;&lt;li&gt;For gliders: Sufficient compensation for the force of the tow line, both at the beginning of a winch launch (tow line horizontal) and at the end (tow line vertical).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The other criteria (upper and lower limits on stick force gradients over speed and load factor) can be tailored with elevator chord, so the horizontal tail surface is not directly affected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end your horizontal tail will be as large as you want your cg range to be wide. Operators like wide cg ranges, so the small drag penalty of a bigger tail surface might be worth it.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Wing airfoil&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Also, wing airfoils with a high pitching moment (think rear loading, i.e. high camber in the rear part) will need a bigger tail surface due to the larger shift of the center of pressure over speed, but have less drag and a higher maximum lift than comparable, old-fashioned airfoils (think NACA 4-digit range), so the wing can be smaller and has less drag, which easily compensates for the increased tail surface.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Do not optimize each surface separately&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If your wing has already an optimized lift distribution, adding more lift in the same &lt;a href=&quot;http://en.wikipedia.org/wiki/Trefftz_plane&quot; rel=&quot;noreferrer&quot;&gt;Treffz plane&lt;/a&gt; will spoil the end result. In the end, it does not make much of a difference at which position in streamwise direction lift is created, only the sum of it counts. Therefore, it might be better to have as little tail loading as possible in the design point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you take the mass of the wing structure in consideration, your optimum lift distribution over the wingspan will &lt;a href=&quot;http://digital.library.unt.edu/ark:/67531/metadc53315/m2/1/high_res_d/19760012005.pdf&quot; rel=&quot;noreferrer&quot;&gt;change to a more triangular shape&lt;/a&gt;, and now it might even make sense to create a small downforce on the tail to reduce the downwash angle in the center section. A lighter wing will require less lift and help to reduce drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HnZPP.png&quot; alt=&quot;General flow direction at wing and tail surface&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think of it this way: The triangular lift distribution produces a higher downwash angle at the tail, and any downforce there would actually point slightly forward, creating induced thrust. Effectively, it helps to equalize downwash over span in the Treffz plane of wing and tail.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-02-01T20:49:09.997" LastActivityDate="2018-02-01T20:49:09.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11722" PostTypeId="2" ParentId="11720" CreationDate="2015-01-14T22:25:26.700" Score="8" Body="&lt;p&gt;I know nothing about &lt;a href=&quot;http://en.wikipedia.org/wiki/Powered_lift&quot;&gt;powered-lift aircraft&lt;/a&gt;, but according to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_15&quot;&gt;14 CFR 61.5&lt;/a&gt; they're a separate category for licensing, like airplane, rotorcraft or glider. It is therefore possible to get a &quot;private pilot powered-lift&quot; certificate without having any flying experience in any other aircraft type. 14 CFR 61.109, 61.129 and 61.163 state the flying requirements for private, commercial and ATP powered-lift ratings respectively and 61.65 has the requirements for a powered-lift instrument rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;61.109(e)(5) does allow substituting some limited airplane (i.e. fixed-wing) experience for powered-lift time:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(5) 10 hours of solo flight time in an airplane or powered-lift&#xA;  consisting of at least—&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are also allowances for using simulator and military experience in lieu of powered-lift flight time, but I couldn't see anything that directly allows rotorcraft experience to count towards powered-lift certification. The fact that powered-lift is a category of its own suggests that the FAA considers them to be significantly different from rotorcraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, you could theoretically start from zero and work to get your private, instrument, commercial and/or ATP ratings with flying time in powered-lift aircraft only. If, that is, you can find a powered-lift aircraft and an instructor: an ATP requires 1500 hours of experience and doing them all in powered-lift aircraft may not be practical (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1163&quot;&gt;61.163&lt;/a&gt; only requires 250 of them to be in a powered-lift aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, I suspect that any civilian powered-lift pilots who are not ex-military are (or will be) people with extensive rotorcraft and/or fixed-wing experience who then follow a training program provided by the aircraft manufacturer. Your insurance company will probably also have a say in who you hire and what experience they have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finding and training those people won't be cheap, but if you're buying up new AW609s then you can probably afford it :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-15T12:44:25.747" LastActivityDate="2015-01-15T12:44:25.747" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11723" PostTypeId="1" AcceptedAnswerId="11730" CreationDate="2015-01-14T23:50:40.773" Score="9" ViewCount="3835" Body="&lt;p&gt;I was looking into engine nacelles. I was not able to understand the design shape of it&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it that in most aircraft, the engine cowl lips on the side are bigger (more blunt) than on the top and bottom.&lt;/p&gt;&#xA;" OwnerUserId="6857" LastEditorUserId="595" LastEditDate="2016-04-15T07:09:31.137" LastActivityDate="2016-04-15T09:00:12.510" Title="Why do engine cowl lips appear larger and more blunt on the sides than on the top and bottom?" Tags="&lt;jet-engine&gt;&lt;engine&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11724" PostTypeId="2" ParentId="2570" CreationDate="2015-01-15T01:51:30.043" Score="1" Body="&lt;p&gt;An aircraft with a grappling hook could do it such as a Cessna which is capable of towing a banner. It wouldn't end well, but he could survive for sure. A Cessna 172 needs about 1,500 feet of runway for landing... depending on fuel load of course. Typical carrier landing zone is only about 1,000 feet. The grappling hook used to load a banner could reduce the inertia enough that the plane would not explode if it caught a landing wire, but I would not recommend it... it'd rip the plane apart. 'Traps' are practiced on land before on sea. It would be very difficult for a Cessna to capture the 'meatball' for an inexperienced pilot on an angle deck. Your runway is constantly drifting right. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The V&lt;sub&gt;S0&lt;/sub&gt; of a Cessna 172 (Down and dirty) is 54Mph, an Aircraft Carrier can easily do 46Mph if turned into the wind. A reduction of 8Mph within 1,000 feet is not impossible... so yes, it's possible.&lt;/p&gt;&#xA;" OwnerUserId="6865" LastEditorUserId="679" LastEditDate="2015-01-15T09:23:24.347" LastActivityDate="2015-01-15T09:23:24.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11725" PostTypeId="2" ParentId="11723" CreationDate="2015-01-15T02:05:34.607" Score="11" Body="&lt;p&gt;Images of 767 and 777 aircraft that I looked at show pretty uniform lips all the way around. This 757 engine (image below) looks thinner on the sides, which is the opposite of what you have seen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aaIu7.jpg&quot; alt=&quot;757 Engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shape of the cowl (and lip) is going to depend mostly on the shape of the nacelle. The 757 engine (image above) has engine accessories at the bottom of the engine, which requires a thicker nacelle to cover, which requires a larger radius on the cowl lip to streamline. As discussed in &lt;a href=&quot;https://aviation.stackexchange.com/questions/7824/shape-of-the-boeing-737-engine&quot;&gt;this question&lt;/a&gt;, the 737 engines have a unique shape to provide ground clearance, so the accessories are pushed to the sides.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-01-15T19:16:28.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11726" PostTypeId="1" AcceptedAnswerId="11728" CreationDate="2015-01-15T03:10:04.683" Score="6" ViewCount="2641" Body="&lt;p&gt;I am developing a game which involves an airport simulation. And I am looking into the general rules that traffic control has for busy airports and am also confused on the terminology of a taxiway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to ICAO taxiway widths have 3 types of labeling which is as follows:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Taxiway Lane&#xA;Taxiway Strip&#xA;Taxiway Shoulder &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;What is the taxiway shoulder? I am fairly sure the lane is the 2 outer yellow lines from the center  taxiway line right? And the strip is the entire taxiway width, but I am unclear on the shoulder label? I could not find an image that showed what this was.&lt;/p&gt;&#xA;" OwnerUserId="6864" LastEditorUserId="572" LastEditDate="2015-02-19T08:43:17.040" LastActivityDate="2015-02-19T08:43:17.040" Title="What do taxiway lane, taxiway strip and taxiway shoulder mean?" Tags="&lt;terminology&gt;&lt;ground-operations&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11727" PostTypeId="2" ParentId="11714" CreationDate="2015-01-15T06:44:42.810" Score="19" Body="&lt;p&gt;Again, since there has been a sparsity of answers, I'll try to add to Simon's excellent answer and give a bit of a different perspective. My answer is dated in that it comes from flying 747-100 and -200 aircraft in the 1990s at the last airline I worked for. Given what I am sure is a wide variability of cockpit crew &amp;amp; cabin crew communication practices around the world, it may still be relevant. Remember, though, this is pre 9/11.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin crew typically would arrive at the airplane before the cockpit crew. The first interaction other than a quick hello as we came onto the airplane was usually the upper deck flight attendant coming into the cockpit within a few minutes of the cockpit crew (captain, first officer, flight engineer) getting settled. Company policy was that the upper deck flight attendant was to check with the cockpit at least every 20 minutes to see if they wanted anything. It's the captain's airplane, though, and she/he could set the tone. I always declined anything until we had reached cruise. Additionally, I would tell the flight attendant that checking every 45 minutes to an hour would be sufficient but that if they just wanted to come up to chat at any time that would be fine. We were usually flying 8 to 12 hour legs. I would also tell them that I preferred to be called Terry rather than Captain, though more often than not they still called me captain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Company policy was that the purser (chief flight attendant if you like) was to personally come to the cockpit to inform the captain that &quot;all doors are closed, all passengers seated.&quot; That was my cue to call for the before-start checklist. Likely the purser had already been to the cockpit earlier to let me know how the loading was going, who was in back, and any problems. I in turn would give the purser the expected flight conditions, estimated time en route and such. I wasn't big on the captain making announcements to the cabin. My policy was to give the info to the purser and let them handle cabin announcements as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next company-required communication was hitting the button that sounds the beep throughout the cabin when we climbed through 10,000 feet, and I'd turn off the seat belt sign then as well. If there were no weather/turbulence problems en route, the next usual communication was a call to the purser shortly before the start of descent. However, typically the purser would have come to the cockpit every couple of hours during the flight to chat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Descending through 10,000 feet I'd hit the cabin tone button twice and turn the seat belt sign on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last cabin communication was hitting the cabin tone button and turning off the seat belt sign after the parking brake was set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hajj flights were a special case. The purser was always one of our people, but the flight attendants were supplied by the national airline we were doing the flights for under contract. The requirements included that the captain be notified if anyone became seriously ill. All Hajj flights were required to have at least one doctor onboard, who would be a Hajji as well. The purser would come into the cockpit to tell the captain, and the captain would ask if the doctor wanted to land for a medical emergency (they never did). The captain was also to be notified if someone died. This was not unusual on Hajj flights, and we carried body bags for that contingency. A death was not a cause for landing short of the destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an area that starts before descent that has religious significance to Muslims because of the proximity to Mecca. It was marked on the IFR en route maps. We were supposed to announce entering that area. I always did that personally because I had learned how to properly pronounce it's name (well, as close as I could). The irony of the situation was that here was a 747 from a Jewish-owned airline, captained by an atheist, telling a plane load of Muslims they were approaching Mecca, Islam's holiest city.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-01-15T07:51:01.617" LastActivityDate="2015-01-15T07:51:01.617" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11728" PostTypeId="2" ParentId="11726" CreationDate="2015-01-15T07:07:19.053" Score="6" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.skybrary.aero/index.php/Taxiway_Surface_Markings_and_Signs&quot; rel=&quot;noreferrer&quot;&gt;Skybrary from EUROCONTROL&lt;/a&gt; and a UK CAA document on taxiways markings (&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/291.pdf&quot; rel=&quot;noreferrer&quot;&gt;Visual Aids Handbook UK CAA CAP 637 (2007)&lt;/a&gt;), the definitions are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Taxiway Strip&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An area which contains the taxiway and gives protection to aircraft from obstacles and other taxiways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dDhGX.jpg&quot; alt=&quot;TaxiStrip&quot;&gt;&lt;br&gt;&lt;sup&gt;Image Source: Transport Canada&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Taxiway Lane&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is ambiguous and could not be found citation on, except for a &lt;a href=&quot;http://www.bazl.admin.ch/dokumentation/grundlagen/02643/02644/index.html?download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1acy4Zn4Z2qZpnO2Yuq2Z6gpJCDe318g2ym162epYbg2c_JjKbNoKSn6A--&amp;amp;lang=de&quot; rel=&quot;noreferrer&quot;&gt;document from the BAZL&lt;/a&gt;. Taxilanes or Taxiway Lanes are dashed taxiways, which give guidance to stands and aircraft parking positions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Taxiway Shoulder&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The taxiway shoulder is the paved or unpaved area beyond the double taxiway edge line, indicating that the load bearing capabilities beyond these lines can be different from the taxiway weight allowance.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="19" LastEditDate="2015-01-15T07:28:04.890" LastActivityDate="2015-01-15T07:28:04.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11729" PostTypeId="2" ParentId="11726" CreationDate="2015-01-15T07:11:45.443" Score="3" Body="&lt;p&gt;Take a look at &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0203.html&quot; rel=&quot;nofollow&quot;&gt;Section 3. Airport Marking Aids and Signs&lt;/a&gt; of the FAA's AIM and &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/publications/media/QuickReferenceGuideProof8.pdf&quot; rel=&quot;nofollow&quot;&gt;AIRPORT SIGN AND MARKING – QUICK REFERENCE GUIDE&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2015-01-15T07:11:45.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11730" PostTypeId="2" ParentId="11723" CreationDate="2015-01-15T07:36:46.053" Score="11" Body="&lt;p&gt;For subsonic aircraft, the nacelle lips need to be blunt and well rounded to accommodate the different flow regimes encountered during flight. At take-off (right side of the image below), the engine will suck in surrounding air, so the stagnation line of the intake flow is well outside of the center of the lip, whereas in cruise (left side of the image below) only the center stream tube of oncoming air is ingested, and much of the air flowing towards the nacelle is spilled over the sides. Accordingly, the stagnation line is well inside of the lip's center. A sharper lip contour would lead to flow separation due to the small radius (and hence the rapid change in direction) the flow would have to endure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kdnvz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kdnvz.jpg&quot; alt=&quot;Streamtube for cruise and landing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Aerodynamic Design of Transport Aircraft by Ed Obert, 2009&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Added to this is the influence of angle of attack, which will shift the stagnation line up or down on the lip. Sideslip will shift it left and right. Nacelles are mounted far ahead of the wing not only for flutter suppression, but also to reduce the wing's influence on the intake flow. I doubt that the added variations of sideslip would be stronger than those of angle of attack, so I agree with @fooot that more bluntness on the side is unusual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Earlier designs used less blunt lips and had problems with flow separation in the intake at low speed, which led to the addition of &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;secondary inlet doors&lt;/a&gt;. Today, the intake is optimized with &lt;a href=&quot;http://en.wikipedia.org/wiki/Computational_fluid_dynamics&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFD&lt;/a&gt; and this means that the radius may be continuously changing over the circumference, due to the influence of wing and fuselage on the flow around the nacelle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here I have to disagree with @fooot, because accessories are mounted close to the engine, and intake lips are quite a bit ahead of the engine face in order to equalize the flow. The flow speed at the engine face is around Mach 0.4 to 0.5, so the intake has to accelerate or decelerate the flow quite a bit, without separation or much cross flow. A lot of that happens already outside of the intake, but still needs some intake length, and most accessories are so far away from the intake lip that they do not influence it's thickness.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-15T09:00:12.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11731" PostTypeId="1" AcceptedAnswerId="11735" CreationDate="2015-01-15T08:12:02.427" Score="15" ViewCount="12520" Body="&lt;p&gt;I recall having read somewhere that “helicopter in forward flight behaves just like a &lt;em&gt;badly trimmed&lt;/em&gt; airplane”. So I'd like to ask:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do helicopters have trim?&lt;/li&gt;&#xA;&lt;li&gt;If so, how does it work?&lt;/li&gt;&#xA;&lt;li&gt;And is the helicopter stable when properly trimmed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-01-15T13:27:33.893" LastActivityDate="2017-05-04T06:39:07.947" Title="Do helicopters have trim? How does it work?" Tags="&lt;aerodynamics&gt;&lt;flight-controls&gt;&lt;helicopter&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11735" PostTypeId="2" ParentId="11731" CreationDate="2015-01-15T12:33:59.860" Score="14" Body="&lt;p&gt;It depends on what you mean by trim. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you mean a a mechanism that allows the pilot to reduce the control forces in order to allow the helicopter to be flown hands off, then the answer is a qualified yes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you mean a &lt;em&gt;trim tab&lt;/em&gt; attached to a control surface, then the answer is no. Many airplanes which have a trim control do not use a trim tab. For example, Pipers have an &lt;em&gt;anti-servo&lt;/em&gt; tab on the elevator, which the pilot uses to reduce control forces. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0jiv.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/BkBdj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since helicopters are unstable -- meaning if you take your hand off the cyclic the aircraft will be in an unusual attitude within a second -- nothing short of electronics and actuators will allow a heli to be flown hands off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But every heli except the smallest ones, have considerable stick forces, which make them difficult to impossible to handle without some kind of assistance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest setup is what you find on the original 4-seat R-44 Astro, which lacked hydraulic assist. On top of the cyclic you will find a 4-way &quot;hat&quot; switch which uses electrical actuators on the cyclic to reduce the control forces necessary to fly it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PtryI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger helicopters have hydraulic assist, which allows the copter to be controlled with just two fingers. Inop hydraulics is considered an emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LCbAx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Big helicopters have a &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Autopilot%23Stability_augmentation_systems&quot; rel=&quot;noreferrer&quot;&gt;stability augmentation system&lt;/a&gt;, which allows the helicopter to be flown hands off. An SAS is required for IFR flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rn5yx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="595" LastEditDate="2015-01-15T16:43:58.700" LastActivityDate="2015-01-15T16:43:58.700" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11736" PostTypeId="2" ParentId="11709" CreationDate="2015-01-15T15:06:34.170" Score="11" Body="&lt;p&gt;A helicopter has 3 separate flight regimes: normal flight, autorotation, and hovering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In normal flight and in an autorotation, a helicopter pilot initiates a turn by applying left or right pressure on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Helicopter_flight_controls#Cyclic&quot; rel=&quot;noreferrer&quot;&gt;cyclic&lt;/a&gt;, the control stick between the pilots legs. Through a series of control rods or actuators, the cyclic causes the &lt;a href=&quot;http://en.wikipedia.org/wiki/Swashplate&quot; rel=&quot;noreferrer&quot;&gt;swash plate&lt;/a&gt; to change the pitch of the blades of the rotor, depending on the position of the blade in its cycle.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To turn the heli, more lift is needed on the outside of the turn than on the inside. Taking into consideration &lt;a href=&quot;http://en.wikipedia.org/wiki/Precession&quot; rel=&quot;noreferrer&quot;&gt;gyroscopic precession&lt;/a&gt;, the swashplate adjusts the blades so that the blade pitch is highest on the outside of the turn and lowest on the inside of the turn, which causes the rotor disc &lt;em&gt;as a system&lt;/em&gt; to tilt to initiate the turn. In a semi-rigid rotor system, the entire disc actually tilts on the &lt;em&gt;teetering hinge&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ao8JO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a fully-articulating rotor system (via the flapping hinge) or on a rigid rotor system (flexible blades), only the individual blades move, although they all move in concert to generate the effect of the entire disk tilting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nhgVl.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the disk starts to tilt horizontally in the direction of the cyclic, the fuselage will follow it along, and the heli rolls into the turn. Once the desired bank angle is established, the cyclic can be neutralized, and the increased airflow over the rotary wing on the outside of the turn will maintain the aircraft in the turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since all the controls on a helicopter are strongly-coupled, the pilot will need to adjust the pitch, yaw, and power in order to control the heli's altitude, fuselage heading, and airspeed, and to correct for ambient conditions such as wind and turbulence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In hovering flight, the helicopter pilot turns the helicopter by use of the anti-torque pedals, which control the yaw axis of the aircraft. And indeed, one can &quot;turn&quot; a helicopter during a flight without initiating it with horizontal movement of the cyclic. To do this,  slow the aircraft to a hover, yaw the aircraft to the desired heading, and re-initiate forward motion. Don't try this in your airplane! &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-15T15:42:03.053" LastActivityDate="2015-01-15T15:42:03.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11737" PostTypeId="1" AcceptedAnswerId="11739" CreationDate="2015-01-15T15:11:06.483" Score="8" ViewCount="2465" Body="&lt;p&gt;The VFR sectionals show a number of airways/routes marked in red. Here are several near KMTH, you can see B-646 extending east of the NDB:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XghfP.png&quot; alt=&quot;Bravo airways near KMTH&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are others in Alaska that are lettered A, R or G, e.g. A-7 runs between the CMQ and MNL NDBs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are these airways or routes and how are they different from Victor airways?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-15T16:15:45.513" LastActivityDate="2015-01-15T17:05:39.767" Title="What is a red airway on the VFR sectional?" Tags="&lt;usa&gt;&lt;navigation&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11739" PostTypeId="2" ParentId="11737" CreationDate="2015-01-15T15:47:25.640" Score="11" Body="&lt;p&gt;These are &lt;em&gt;Red Federal Airways&lt;/em&gt;, and can be found in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400.9.pdf&quot; rel=&quot;noreferrer&quot;&gt;Order 7400.9&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Red&lt;/em&gt; airways are one of a &lt;a href=&quot;http://propspistonsandoldairliners.blogspot.com/2009/12/how-to-fly-airways-1950-style.html&quot; rel=&quot;noreferrer&quot;&gt;1950s-ish system of airways&lt;/a&gt;: Red, Blue, Green, Amber, which are designated by an NDB (rather than a VOR or VORTAC for a V or J route).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Green and Red airways go east/west, and Blue and Amber routes go north/south. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These routes were prioritized: GARB, with Green routes having the highest priority.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cRsx3.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cRsx3.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="1696" LastEditDate="2015-01-15T17:05:39.767" LastActivityDate="2015-01-15T17:05:39.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11741" PostTypeId="2" ParentId="11677" CreationDate="2015-01-15T22:00:37.920" Score="1" Body="&lt;p&gt;In the &lt;em&gt;highly&lt;/em&gt; unlikely event of this, a person who knows something about planes would get instructions from ATC of how to fly. A few years back there was a helios A320 which had a pressurisation issue. Everyone was un conscious and a member of the cabin crew attempted to land the plane. Thou, it was un successful. To sum up, ATC Would instruct someone how to fly and then auto land the plane, and this would most likely never happen. &lt;/p&gt;&#xA;" OwnerUserId="4433" LastActivityDate="2015-01-15T22:00:37.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11742" PostTypeId="1" AcceptedAnswerId="11743" CreationDate="2015-01-15T22:41:30.973" Score="17" ViewCount="2144" Body="&lt;p&gt;Last month (December 2014), there were news that &lt;a href=&quot;http://www.nj.com/essex/index.ssf/2014/12/woman_23_dies_aboard_london-to-newark_flight_monday.html&quot; rel=&quot;noreferrer&quot;&gt;a passenger passed away&lt;/a&gt; during a flight. As mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/a/11727/65&quot;&gt;this answer&lt;/a&gt;, it appears that it is not a very uncommon scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an unfortunate incident like this, how is this matter handled?&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-05-24T04:09:16.633" Title="What happens if a passenger dies mid-flight?" Tags="&lt;airliner&gt;&lt;emergency&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11743" PostTypeId="2" ParentId="11742" CreationDate="2015-01-15T22:41:30.973" Score="20" Body="&lt;p&gt;In the event of a passenger dying on an airplane during flight, each case is different depending on the location of the airplane, the duration of that flight and the wishes of family or friends traveling with the deceased passenger.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What happens to the flight?&lt;/strong&gt;&lt;br&gt;&#xA;If the death occurs before takeoff or shortly after takeoff, the airplane is landed back to that airport or the nearest airport. If it happens mid-flight, normally the flight is continued to its destination.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Where is the deceased passenger placed?&lt;/strong&gt;&lt;br&gt;&#xA;If there is a seat available in first or business classes, the deceased person is moved there and covered with a blanket. If it is a full flight, that person may simply be strapped in more tightly and covered. This is done to ensure that the body is out of view of other passengers. A deceased person is never placed in the lavatory. It is not respectful and a major security concern.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What happens at arrival airport?&lt;/strong&gt;&lt;br&gt;&#xA;The arrival airport is informed in advance about the situation. Hence police, ambulance and coroner are available. Some airlines keep body bags on board. Normally the deceased person is placed on a stretcher and is carried from the rear exit of the airplane using a lift truck and then placed in an ambulance. This might be done after other passengers have exited the airplane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;What are the regulations?&lt;/strong&gt;&lt;br&gt;&#xA;FAA have regulations addressing several emergencies, but not specifically this one. An FAA spokesperson &lt;a href=&quot;http://seattletimes.com/html/travel/2004249398_webdeathonplane28.html&quot;&gt;mentioned&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FAA spokesman Les Dorr said he was unaware of any policies that&#xA;  specifically address what should be done if someone dies in flight.&#xA;  The airlines make those decisions on their own.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.news.com.au/travel/travel-updates/what-really-happens-when-someone-dies-on-a-plane/story-fnizu68q-1226936994935&quot;&gt;This article&lt;/a&gt; mentions some incidents of this situation happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.medaire.com/&quot;&gt;MedAir&lt;/a&gt; is a company which provides airlines with medical help from emergency care doctors on the ground. They &lt;a href=&quot;http://www.nj.com/news/index.ssf/2014/12/how_airlines_respond_when_passengers_dies_onboard.html&quot;&gt;estimate that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... there is one death for every 8 million passengers from the airlines [they] serve ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-01-16T19:26:23.207" LastActivityDate="2015-01-16T19:26:23.207" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11744" PostTypeId="1" AcceptedAnswerId="11752" CreationDate="2015-01-15T23:21:05.557" Score="36" ViewCount="15506" Body="&lt;p&gt;As far as I know from the working principle of jets engines, compressed air in the combustion chamber (or combustion canister) is mixed with fuel. The ignited mixture expands backwards to turn the turbine rotors and perpetuates the work cycle. Eventually, the left over hot gas creates the thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although heated gas expands in every direction in space, why does the combustion-gas only expand in one direction, towards the turbine? &lt;/p&gt;&#xA;" OwnerUserId="6870" LastEditorUserId="935" LastEditDate="2015-12-20T14:41:54.337" LastActivityDate="2020-04-30T13:31:31.847" Title="Why do gases in the combustion chamber only flow one direction to the gas turbine in a jet engine?" Tags="&lt;jet-engine&gt;&lt;combustion&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11745" PostTypeId="2" ParentId="11744" CreationDate="2015-01-15T23:29:20.267" Score="19" Body="&lt;p&gt;The air in the compressor is both compressed and moving downstream towards the combustion section. The combustion does not create enough pressure to overcome all of that, and there is lower pressure as the air gets expanded through the turbine sections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the pressure in the compressor section drops too much, the combustion flames do expand in both directions. This is called a &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7799/why-do-jet-engines-sometimes-spit-out-flames-after-ingesting-birds&quot;&gt;compressor surge&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-01-15T23:29:20.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11746" PostTypeId="1" CreationDate="2015-01-16T01:29:55.723" Score="16" ViewCount="1334" Body="&lt;p&gt;Let's say I'm on a long-range flight at my requested altitude of FL250, and I am handed off into a very busy sector where the controller tells me &quot;Descend and maintain FL210, for traffic.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At FL250, my fuel burn and capacity is sufficient to make the flight with better than IFR reserves. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if I have to descend to a lower altitude, my fuel burn will increase and my true airspeed decrease to the point where I would have to stop en route for fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I describe my situation to ATC in such as way as they will allow me to stay at 250?  Controllers do have some obligation to get you to your intended point of landing, and if giving you an altitude, airspeed, or vector that will adversely affect your flight, shouldn't there be some way to describe that?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about saying, &quot;if you give us 210, we're going to have to declare &lt;a href=&quot;http://lessonslearned.faa.gov/Avianca52/INFO_08004.pdf&quot; rel=&quot;noreferrer&quot;&gt;minimum fuel&lt;/a&gt;&quot;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-18T16:47:52.570" LastActivityDate="2018-06-09T07:01:12.350" Title="If I'm on a IFR flight plan with appropriate IFR reserves, and I'm given a lower altitude which will consume more fuel, what should I do?" Tags="&lt;air-traffic-control&gt;&lt;flight-planning&gt;&lt;refueling&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11747" PostTypeId="1" AcceptedAnswerId="11755" CreationDate="2015-01-16T03:02:26.920" Score="5" ViewCount="1641" Body="&lt;p&gt;Is it possible for aircraft to transfer from low to high airways?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, you must be flying below 18000 feet to be able to use a Victor airway, while you must be at FL180 or above to use a Jet airway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is possible to do so on one flight plan, at which point would you switch over, and what altitude would you need to be at?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've looked at various low and high altitude enroute charts, as well as FAA guides on using these, but they don't seem to really point this out.&lt;/p&gt;&#xA;" OwnerUserId="72" LastActivityDate="2015-01-16T07:46:29.907" Title="Is it possible for aircraft to transfer from low to high airways?" Tags="&lt;instrument-flight-rules&gt;&lt;faa&gt;&lt;flight-planning&gt;&lt;navigation&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11748" PostTypeId="1" AcceptedAnswerId="11754" CreationDate="2015-01-16T03:22:37.477" Score="18" ViewCount="5236" Body="&lt;p&gt;In a small and un-busy airport, the same controller can be the ground and tower at the same time. If the sector is un-busy (e.g. late at night), he may also be a sector, ground and tower all at the same time. At busy airports of course, ground and tower are two persons. Sometimes even ground is split to &quot;Ground South&quot; and &quot;Ground North&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there is a threshold where the communication has to be split into two, either because the frequency would be too busy (only one person can talk on the frequency at any time), or there are so many planes that a controller would start making mistakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that threshold? (Is it a concrete number, or some other conditions which can be objectively determined?)&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-01-16T06:52:39.773" LastActivityDate="2016-04-14T14:20:07.553" Title="What is the maximum number of planes a controller can control?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11749" PostTypeId="2" ParentId="11748" CreationDate="2015-01-16T03:55:51.373" Score="5" Body="&lt;p&gt;Chuckling here, as this is a hotly argued topic in controller circles. There is no direct official number. One airplane can be all a person could work(major emergency lots of coordination, etc.), or they could work 20+ and not break a sweat, it heavily depends on the nature of what's occuring and the staffing at the facility, the positions that are designed at the facility(various sectors at a tracon, where there's designated airspace for the position and frequency).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the design and course of life of facilities, they constantly evaluated the positions they need during peak traffic times, to slow times, and the required staffing levels for those positions. Sometimes all you need 99% of the time is two positions, so that's what they'll aim to staff for, other times, based on history and operators at the airport you can get a good idea when your peaks and valleys occur and plan position distribution accordingly, with the staffing you have.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-01-16T03:55:51.373" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11750" PostTypeId="2" ParentId="11747" CreationDate="2015-01-16T04:46:48.927" Score="4" Body="&lt;p&gt;Yes, this happens every day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, airliners coming southbound on high altitude Jet routes to SFO will be given the POINT REYES ONE Arrival, and you can see below that the segment from Point Reyes to HADLY intersection overlies the low-altitude Victor airway V27:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sv8de.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-16T04:46:48.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11751" PostTypeId="2" ParentId="11555" CreationDate="2015-01-16T04:59:48.207" Score="8" Body="&lt;p&gt;Adding to Reirab and Brian Towers' &lt;strong&gt;superb&lt;/strong&gt; answers on this topic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several ways an electronic device can interfere with aircraft operations, but the likelihood depends on age, aircraft design factors, and the nature of the EMI aggression (frequency, modulation type, and power -- there are also broadband EMI sources on aircraft, but we can safely disregard these for the purposes of this discussion, as PEDs generally are narrowband emitters unlike, say, an electric hydraulic pump which lost its interference suppression capacitors, spewing broadband hash as a result).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical concern, though, is of interference with an aircraft's sensitive navigation (ILS/LOC, G/S, NDB, GPS/WAAS, radio altimeter) and communication (HF, VHF, SATCOM) receivers (it's possible to interfere with the transponder/TCAS and weather radar signals as well, but those aren't quite the same level of concern as say the glideslope is), from &lt;em&gt;intentionally emitting&lt;/em&gt; PEDs -- cell phones (especially GSM phones, as the GSM air interface is more EMI-prone than that a CDMA phone is) and 2.4GHz or 5GHz devices (WLAN, BT) are the main concerns on this front, although unintentional emitters (anything in airplane mode) are also a source of potential trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, comms interference takes an immediately noticeable form -- &quot;what's that funny noise in my headset?&quot; (Pilots of small General Aviation aircraft have  reported this on a regular basis.)  This is in contrast with interference to navigational receivers, which may be subtle but not immediately troublesome (losing a bird in a large visible GNSS constellation), obvious (a fail flag on a VOR or LOC), or insidious (a false glideslope indication).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the consequences are high here, especially during coupled or autoland approaches -- a human pilot can see that a full fly-down indication appearing out of the blue at 300' RA during an otherwise stable ILS approach is bogus and whack the TOGA button to get the crew some time to tell the noisemaker to zip their electronic lips, but an autoland computer won't know the difference and will follow it blindly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good piece of news is that in the somewhat-more-common case of an unintentional emitter (a device in airplane mode, for instance), the emissions tend to be simple, unmodulated carriers -- I see this as more likely to trigger a FAIL flag than a flight path deviation.  (I will put another question up on this topic, even -- it's worth asking about, and perhaps even an experiment or three.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, due to the large number of airline flights yearly (66 million according to ACI as per reirab's comment below), something that happens once in every 10^7 landings (Extremely Remote according to AC 25.1309) will happen every other month on average, and even something that happens once in 10^9 landings (Extremely Improbable according to AC 25.1309) is bound to happen every 15 years or so!  The reported PED interference instances are not nearly as severe in consequences as the 'worst case' of a full 'fly down' during the late phase of a coupled or autoland approach (or false radio altimeter readings causing a grossly premature mode shift during autoland), though, but the probability of PED EMI with aircraft systems on any given flight is enough to make it a concern -- 75 events were reported worldwide to the IATA from 2003 to 2010, and given this number, we get a probability of roughly 1 in 10^7 for PED interference on a flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this, we can conclude that it would be highly unwise to take the chance of having a device talk all over the ILS signals during a critical phase of flight -- you would have to find a way to reduce the probability of PED interference with aircraft systems to 1 in 10^11 or better (this is 100 times less likely than what is currently allowed for a catastrophic event) in order to have a chance of challenging this wisdom.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-01-17T02:04:14.053" LastActivityDate="2015-01-17T02:04:14.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11752" PostTypeId="2" ParentId="11744" CreationDate="2015-01-16T05:39:04.987" Score="31" Body="&lt;p&gt;It is actually not that simple to ensure the proper gas speed in a gas turbine. In the compressor you want to limit the flow speed over the compressor vanes to the high subsonic range, so the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;inlet has to decelerate the flow&lt;/a&gt; down to approx. Mach 0.4 - 0.5. Less would mean less throughput and consequently less thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This speed, however, is far too high for ignition. The &lt;a href=&quot;https://aviation.stackexchange.com/questions/10002/why-is-the-combustor-volume-of-a-jet-engine-decided-by-altitude/10014#10014&quot;&gt;fuel needs some time to mix with the compressed air&lt;/a&gt;, and if flow speed is high, your combustion chamber becomes very long and the engine becomes heavier than necessary. Therefore, the cross section leading from the compressor to the combustion chamber is carefully widened to slow down the airflow without separation (see the section below named &quot;diffusor&quot;). Around the fuel injectors you will find the lowest gas speed in the whole engine. Now the combustion heats the gas up, and makes it expand. The highest pressure in the whole engine is right at the last compressor stage - from there on pressure only drops the farther you progress. This ensures that no backflow into the compressor is possible. However, when the &lt;a href=&quot;http://en.wikipedia.org/wiki/Compressor_stall&quot; rel=&quot;nofollow noreferrer&quot;&gt;compressor stall&lt;/a&gt;s (this is quite like a wing stalling - the compressor vanes are little wings and have the same limitations), it cannot maintain the high pressure and you get reverse flow. This is called a &lt;a href=&quot;https://aviation.stackexchange.com/questions/7799/why-do-jet-engines-sometimes-spit-out-flames-after-ingesting-birds&quot;&gt;surge&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The graph below shows typical values of flow speed, temperature and pressure in a jet engine. Getting these right is the task of the engine designer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eLcXa.jpg&quot; alt=&quot;Plot of engine flow parameters over the length of a turbojet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plot of engine flow parameters over the length of a turbojet (picture taken from &lt;a href=&quot;http://cast-safety.org/pdf/3_engine_fundamentals.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; publication)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rear part of the engine must block the flow of the expanding gas less than the forward part to make sure it continues to flow in the right direction. By keeping the cross section of the combustor constant, the engine designer ensures that the expanding gas will accelerate, converting thermal energy to kinetic energy, without losing its pressure (the small pressure drop in the combustor is caused by friction and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rayleigh_flow&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rayleigh effect&lt;/a&gt;). Now the accelerated flow hits the turbine, and the pressure of the gas drops in each of its stages, which again makes sure that no backflow occurs. The turbine has to take as much energy from the flow as needed to run the compressor and the attached pumps and generators without blocking the flow too much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The remaining pressure is again converted to speed &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/adjustable-area-jet-engine-nozzles&quot;&gt;in the nozzle&lt;/a&gt;. Now the gas is still much hotter than ambient air, and even though the flow at the end of the nozzle is still subsonic in modern airliner engines, the actual flow speed is much higher than the flight speed. The speed difference between flight speed and the exit speed of the gas in the nozzle is what produces &lt;a href=&quot;https://aviation.stackexchange.com/questions/9144/how-is-engine-thrust-measured-in-flight&quot;&gt;thrust&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter engines usually have supersonic flow at the end of the nozzle, which requires careful shaping and adjustment of the nozzle contour. Read all about it &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/adjustable-area-jet-engine-nozzles&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-30T13:31:31.847" LastActivityDate="2020-04-30T13:31:31.847" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="11753" PostTypeId="2" ParentId="11744" CreationDate="2015-01-16T06:27:35.027" Score="12" Body="&lt;p&gt;&lt;em&gt;Disclaimer: I may have spent several hours on Wikipedia at one point trying to answer this question for myself!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines use the Brayton cycle, which is a &quot;isobaric&quot; process during combustion, meaning it keeps pressure constant during that phase.  This is in contrast to the Otto cycle of a typical four-stroke piston engine, which is &quot;isochoric&quot; during combustion, meaning it keeps volume constant during that phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Brayton cycle consists of 3 parts, of which combustion occurs in the middle&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Incoming air is compressed.  This requires work which is supplied by turbine at the end of the cycle while the engine is operating or an external motor when starting the engine.  This raises the pressure of the air (decreasing the volume).&lt;/li&gt;&#xA;&lt;li&gt;Fuel is mixed with the air and ignited.  This is a continuous process (unlike piston engines).  This process is &quot;constant pressure,&quot; which is the part that you are asking about.  It's not intuitively obvious why, so we'll dig into it in the next section.  The end result is a larger volume of air at the same pressure as the inlet to the chamber from the compressor.&lt;/li&gt;&#xA;&lt;li&gt;The air is passed through a turbine in a shape which decreases the pressure from the compressed pressure to atmospheric pressure.  It uses this turbine to run the compressor.  All pressure differential which is not needed to power the compressor is used to accelerate the air backwards to provide thrust.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So how does this &quot;constant pressure&quot; thing work?  Treat the combustion chamber as a sort of box for a moment.  Whether there is combustion or not, there's going to be generally constant pressure inside the box.  Air is being pushed into it by the compressor, with some velocity and pressure.  If the turbine at the end of the chamber can &quot;dispose&quot; of air at a high enough velocity, it can keep the pressure at the far end of the chamber equal to that of the front end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how does this &quot;constant pressure&quot; thing actually keep the flame front from advancing forward?  &lt;strong&gt;The trick is that the flame front &lt;em&gt;is&lt;/em&gt; trying to advance forward, but the velocity of the air through the chamber matches the speed of the flame front, keeping it in a constant location in the chamber.&lt;/strong&gt;  This is a dynamic process, so we'll need some dynamics.  They key detail is that the turbine and compressor are on one axle, so what happens to one affects the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider three cases which compare the airflow velocity to the fuel:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Too slow for combustion rate&lt;/strong&gt; — this happens if you increase the throttle, or at the starting of the engine.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The combustion starts to win, advancing the flame front towards the compressor, just like you'd think it would.&lt;/li&gt;&#xA;&lt;li&gt;However, now the dynamics come in.  As the flame front moves forward, it raises the pressure at the outlet of the compressor, slowing the velocity of air through the compressor.&lt;/li&gt;&#xA;&lt;li&gt;This means the compressor doesn't have to pressurize as large of a volume of air, so its load decreases.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;(The compressor IS having to pressurize the volume to a higher pressure, but its trivial to see that this effect is overshadowed by the decreased volume of air by considering the edge case of a very weak compressor which clearly backs up if you pressurize it from the other side.)&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;The turbine is still seeing the same pressure, but its less loaded.  This spins the turbine up, increasing air flow leading us to...&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Trimmed engine&lt;/strong&gt; — This is where planes normally try to operate, and it's where you don't see flames propagating forward.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In this state, the velocity of the incoming air is enough to match the flame front's propagation forward.&lt;/li&gt;&#xA;&lt;li&gt;The flame front keeps trying to move forward, but air is shoved in front of it just as fast as it can burn.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Too fast for combustion rate&lt;/strong&gt; — this happens if you decrease the throttle.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With less fuel, the flame front begins to fall backwards towards the turbine.&lt;/li&gt;&#xA;&lt;li&gt;As in the &quot;too slow&quot; case, dynamics come into play.  As the flame front moves backwards, this also decreases the pressure on the inlet to the combustion chamber, and the compressor.&lt;/li&gt;&#xA;&lt;li&gt;The turbine now sees more load, spinning the turbine down.  Slowing the turbine decreases airflow through the compressor, bringing us back towards a trim engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One takeaway from this pattern is why jet engines cannot change thrust quickly.  If you rapidly add fuel by throttling up, you choke the engine, so you don't get much extra power until the turbine and compressor can spin up to equalize the engine.&lt;/p&gt;&#xA;" OwnerUserId="6873" LastEditorUserId="4474" LastEditDate="2015-12-23T23:29:06.270" LastActivityDate="2015-12-23T23:29:06.270" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11754" PostTypeId="2" ParentId="11748" CreationDate="2015-01-16T06:57:01.350" Score="14" Body="&lt;p&gt;There is no fix maximum a controller is allowed to have under control, as &lt;a href=&quot;https://aviation.stackexchange.com/a/11749/572&quot;&gt;the other answer&lt;/a&gt; already pointed out. The airspace under control of ATC is divided up into sectors containing the airways to and from airports within that sector or in upper sectors, airways just for en-route traffic. (see also: &lt;a href=&quot;https://aviation.stackexchange.com/questions/11506/why-do-pilots-use-airways-instead-of-just-flying-direct-every-time/11507#11507&quot;&gt;Why do pilots use airways instead of GPS direct?&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sectors can be merged during off-peak hours, split back into separate sectors during peak hours and in the case of TMA or approach sectors, the controller owning the sector can receive additional help by splitting the approach sector further and using different controllers for different tasks within that sector: Feeder/Pickup - Director - Departure Controller. The thresholds of when a sector is split is dependent on many factors, like weather, runway in use, outside influences like adjacent sectors having more traffic that usual, special occurances within that sector like parachute jumper drops. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sectors also vary in size and capacity based on their intended use. While TMA/Approach sectors are rather small and need to accomodate arriving traffic into an airfield, an enroute or upper sector can be significantly larger in size, lateral and vertical. Again, this is individual to each sector, because some factors which hold true for TMA sectors do not apply to enroute upper sectors and vice versa. It also really depends on the controller working the sector and his personal limits, favorite procedures and work practice. A few examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A TMA controller using vectors to the approach instead of standard arrival routes or transitions will have more workload to monitor and sequence aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The minimum radar separation in TMA sectors and upper sectors can be either 3NM or 5NM. While upper sectors are larger in size, they have to maintain a greater separation, so in some cases, an upper sector twice or multiple times the size of a TMA sector will only be able to accomodate the same number of aircraft (ceteris paribus) before reaching saturation.&lt;/li&gt;&#xA;&lt;li&gt;A controller having to work with special situations such as aircraft in distress or student pilots requiring more attention than experienced pilots, will reduce the controllers personal capacity.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In summary, to answer your question: There is a situation and controller based threshold, at which saturation will be reached. Controllers are trained to anticipate this threshold and make their supervisor aware of the situation beforehand, so that measures can be taken. There is however no fixed numerical maximum, unless specified in the ARTCC/ACC's operating procedures.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-01-16T08:53:52.307" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11755" PostTypeId="2" ParentId="11747" CreationDate="2015-01-16T07:46:29.907" Score="6" Body="&lt;p&gt;The use of airways is, as you already specified, based on altitude/flight level. To be able to transition from higher airways to lower airways and vice versa, they need to intersect at NAVAIDs, such as fixes, VORs or NDBs. Where no restrictions are in place for the use of an airway, the flightplan can just contain the fix where the transition from lower to upper airway will take place. Let's take a look at this flightplan route from EGLL - London Heathrow to EDDG - Münster-Osnabrück:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;DET UL6 DVR UL9 KONAN UL607 SPI UY862 PODEN Y862 KENUM UZ907 ABAMI Z907 HMM&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Lower and upper airways in Europe are distinguished by prefixing the airway designator with a &lt;strong&gt;U&lt;/strong&gt; for &lt;strong&gt;U&lt;/strong&gt;pper. At the end of our flight to Münster, we intend to switch from &lt;strong&gt;UZ907&lt;/strong&gt; to &lt;strong&gt;Z907&lt;/strong&gt;, because &lt;strong&gt;UZ907&lt;/strong&gt; does not connect &lt;code&gt;KENUM&lt;/code&gt; to &lt;code&gt;HMM&lt;/code&gt;. The flightplan routing validator at the &lt;a href=&quot;https://www.public.nm.eurocontrol.int/PUBPORTAL/gateway/spec/index.html&quot;&gt;CFMU&lt;/a&gt; understands that &lt;code&gt;HMM&lt;/code&gt; is a STAR/transition entry point to Münster and therefore considers the airways altitude restrictions to be met during descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this was not the case and we would like to use airways restricted to certain altitudes/flightlevels, we would need to indicate this in the flightplan. Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airways Z1 can only be used between FL195 and 245, airways UZ2 can only be used above FL245. We want to file our flightplan with a step climb and a final cruise level of FL290:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With RFL290 entered into the validator, the flightplan would not be accepted, as Z1 is only available below FL245. The portion of the flightplan to be accepted would need to be:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;[...] ABCDE/F230N0260 Z1 FGHIJ/F290N0270 UZ2 KLMNO [...]&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;In summary, you can switch between upper and lower airways, if you can meet the altitude/flightlevel restrictions and any other restriction bound to the airway.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ICAO flavored anwer added on request by question op, even though original question is tagged with FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-01-16T07:46:29.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11756" PostTypeId="1" AcceptedAnswerId="11774" CreationDate="2015-01-16T09:14:47.217" Score="14" ViewCount="1427" Body="&lt;p&gt;I have read about &lt;a href=&quot;https://aviation.stackexchange.com/questions/241/what-are-the-operational-differences-between-an-airplane-equipped-with-a-constan/247#247&quot;&gt;the operational differences between constant speed and fixed pitch propellers&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being a World War II buff, I was reminded of reading once about both principles being used in period fighter planes, with the Germans preferring one and the British preferring the other, but that's about all that I can recall. (That might have been a solid 20 years since...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;How would the above-mentioned &quot;operational differences&quot; apply to WWII-period warbirds specifically, and does anyone have links or pointers to relevant reading material?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think a period warbird has a quite different set of requirements on its performance and handling characteristics, which is why I think this separate question is warranted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not so much interested in the fine technical details (I don't want to build / maintain / model one of those planes based on this information), but rather striving for a better understanding of the relative performance characteristics of those (IMHO) most beautiful planes of all time.&lt;/p&gt;&#xA;" OwnerUserId="2401" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-04-22T00:32:33.297" Title="What operational differences were there in WWII for constant speed vs. fixed pitch propeller warbirds?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11757" PostTypeId="1" AcceptedAnswerId="11758" CreationDate="2015-01-16T09:40:03.383" Score="5" ViewCount="440" Body="&lt;p&gt;Does every international flight have more than one flight route in the flight plan?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, after the incident with MH-17, most of the flights were diverted from that route. Were the alternate routes already planned or were they chosen at that moment? If they were chosen at that moment, who planned the new routes?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="3825" LastEditDate="2015-03-03T23:20:07.580" LastActivityDate="2015-03-04T00:46:51.250" Title="Do transatlantic flight plans have alternates routes?" Tags="&lt;transatlantic&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11758" PostTypeId="2" ParentId="11757" CreationDate="2015-01-16T09:44:06.167" Score="10" Body="&lt;p&gt;Each airborne flight has only one flightplan, which was submitted for that particular flight.&#xA;The routing is embedded into that flightplan and only that one routing is valid for that flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case the routing is no longer available for the next flight due to airspace closure via NOTAM or airways being restricted by time of flight / day of flight, another routing will be used for that flight and submitted in the flightplan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case the routing needs to be changed for an already airborne flight, a new IFR clearance is read to the crew en-route, which alters the existing flightplan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternate routings are usually managed by the airline's dispatch / planning centre and the best routing for a specific flight is created by the dispatchers, taking into account weather, NOTAMS, restrictions and many other factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;En-route changes to a flightplan are made by ATC units and their data processing centres, if an impromptu change needs to be made due to airspace closures or other restrictions coming into effect which were unforseen.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-01-16T09:44:06.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11759" PostTypeId="1" CreationDate="2015-01-16T09:45:06.393" Score="12" ViewCount="3123" Body="&lt;p&gt;In regards to &lt;a href=&quot;http://www.bbc.com/news/technology-30817693&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; on BBC, which discusses the use of streaming technology to allow passengers to watch films/TV shows etc. on their portable devices, the following statement caught my eye:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It would increase the drag of our aircraft by 2%, which equates to 20&#xA;  million euros [$23.6m; £15.5m] in extra fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is this cost increase purely to do with an increase in weight and additional drag owing to the new equipment required or is there any other factors at play here?&lt;/p&gt;&#xA;" OwnerUserId="6813" LastEditorUserId="64" LastEditDate="2015-10-30T02:53:18.773" LastActivityDate="2015-10-30T02:53:18.773" Title="How does new media streaming technology equate to fuel cost increase?" Tags="&lt;fuel&gt;&lt;weight-and-balance&gt;&lt;electronics&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11760" PostTypeId="1" AcceptedAnswerId="11769" CreationDate="2015-01-16T09:45:43.137" Score="19" ViewCount="13356" Body="&lt;p&gt;I know bird strikes are a major issue for many airports, and that measures are taken to keep birds away.&lt;br&gt;&#xA;There are some obvious things airports can do like not to have any stray garbage, food, etc. in the open, but I'm sure other less obvious methods are also used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly are some of the widely used techniques to keep birds away from airports?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-01-16T20:28:24.907" LastActivityDate="2019-06-14T21:12:01.413" Title="What are the ways to keep the birds away from airfields?" Tags="&lt;safety&gt;&lt;airport&gt;&lt;birds&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11761" PostTypeId="2" ParentId="11760" CreationDate="2015-01-16T09:53:36.047" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://birding.about.com/od/birdconservation/a/birdstrikes.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;about.com&lt;/a&gt; has a good article which lists the many methods that are used to scare birds away from airports. It includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Modify the habitat: Remove sources of food, such as seed-bearing plants, use insecticides to eliminate insects as a food source, remove bushes and plants that can be used for nesting&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The use of visual devices (lasers) or audio (sonic cannons, recordings) to scare away birds&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Trained falcons, dogs, or other predators to make the airport inhospitable to birds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Another source: &lt;a href=&quot;http://icwdm.org/handbook/birds/birdAirport.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Birds at Airports - Internet Center for Wildlife Damage Management&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UpAne.jpg&quot; alt=&quot;Bird Control&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: WikiMedia Commons - Author: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Bird_control.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bluescan sv.wiki&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-06-03T11:42:05.773" LastActivityDate="2015-06-03T11:42:05.773" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11762" PostTypeId="2" ParentId="11759" CreationDate="2015-01-16T10:57:28.940" Score="18" Body="&lt;p&gt;Because it says &amp;quot;drag&amp;quot;, my &lt;strong&gt;guess&lt;/strong&gt; is that implies an external antenna.&lt;/p&gt;&#xA;&lt;p&gt;For example (which I found using a Google search),&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aerosat.com/products/products_ku_aircraft_antenna.asp&quot; rel=&quot;noreferrer&quot;&gt;Commercial and Large VIP Aircraft Broadband Internet Solutions&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;HR6400 Antenna System&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;The HR6400 antenna system for commercial and large VIP aircraft&#xA;provides passengers and crew true wireless broadband Internet access.&#xA;No matter where you fly - over land or water in any region of the&#xA;world - you can browse the Internet, send and receive emails in&#xA;real-time, use Voice-Over-IP (VoIP) telephony, access your VPN,&#xA;conduct video conferencing, and watch IP television.&lt;/p&gt;&#xA;&lt;p&gt;The emerging standard for Ku-band systems with the most efficient&#xA;Ku-band antenna available, &lt;strong&gt;the HR6400 is mounted on the aircraft's&#xA;fuselage&lt;/strong&gt;, providing all the performance you need in the smallest&#xA;possible footprint. &lt;strong&gt;The easy-to-install HR6400 comes complete with&#xA;antenna&lt;/strong&gt;, antenna control unit, high power transceiver, &lt;strong&gt;radome, and&#xA;radome attachment ring&lt;/strong&gt;. It covers everything from the energy coming&#xA;from the satellite to the modem connection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For example, here is a typical antenna installation (not necessarily the one mentioned above) on a 737:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5V4Nw.jpg&quot; alt=&quot;Installation on aircraft&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="556" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-16T17:49:27.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11763" PostTypeId="2" ParentId="11760" CreationDate="2015-01-16T12:35:05.050" Score="6" Body="&lt;p&gt;On a visit to Blackpool Airport control tower a few years ago, they mentioned that they flew a hawk/falcon (not sure which) every day to deter birds&lt;/p&gt;&#xA;" OwnerUserId="6812" LastActivityDate="2015-01-16T12:35:05.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11765" PostTypeId="2" ParentId="11759" CreationDate="2015-01-16T14:01:19.057" Score="8" Body="&lt;p&gt;It is important to distinguish the streaming of media from the on-board server, and an internet connection to the outside world. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first is just a matter of setting up an access point inside the cabin that wouldn't have any impact on the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The latter requires some sort of antenna that probably needs to be placed outside to achieve a decent connection. There are many proposal for those, one for instance is &lt;a href=&quot;http://ec.europa.eu/research/transport/projects/items/retina_en.htm&quot;&gt;here&lt;/a&gt;). Note that in the background section it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Current aeronautical antenna solutions have drawbacks in terms of cost (active phased arrays) or drag (dish antennas).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess that in the interview Mr Hurley was referring to those dishes, as other projects seems to have a definitely minor impact on an aircraft cross section.&lt;/p&gt;&#xA;" OwnerUserId="2345" LastActivityDate="2015-01-16T14:01:19.057" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11766" PostTypeId="1" CreationDate="2015-01-16T14:53:52.247" Score="29" ViewCount="37706" Body="&lt;p&gt;In fighter aircraft, we know that they have good enough of maneuverability. But in case of a passenger airplane, if a stall happens is the aircraft maneuverable enough to recover from it?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="64" LastEditDate="2015-01-16T17:12:46.433" LastActivityDate="2015-01-18T19:59:55.427" Title="Can a large passenger aircraft recover from a stall?" Tags="&lt;commercial-aviation&gt;&lt;aircraft-performance&gt;&lt;stall&gt;" AnswerCount="9" CommentCount="5" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11767" PostTypeId="2" ParentId="11766" CreationDate="2015-01-16T15:10:48.823" Score="6" Body="&lt;p&gt;Yes and no.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a stall happens while the plane is low to the ground without sufficient power to maintain altitude, there may not be time to recover.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At altitude, there is plenty of time for a plane to recover from a simple stall, and yes the plane has the maneuverability to do so.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other conditions, like severe icing, may render the plane unable to recover.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this assumes a plane without mechanical problems.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;Air France flight 447&lt;/a&gt; had airspeed sensor problems and the pilots were presented with confusing information, they stalled the plane at altitude and rode it down into the ocean.  All aboard perished.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="64" LastEditDate="2015-01-16T17:12:33.933" LastActivityDate="2015-01-16T17:12:33.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11768" PostTypeId="2" ParentId="11766" CreationDate="2015-01-16T15:25:56.627" Score="21" Body="&lt;p&gt;An airliner certainly has the ability to recover from a stall, given sufficient height and power. Moreover stall recovery isn't about maneuverability as such. A fighter jet is more difficult to recover from a stall than a Cessna 150, but the Cessna is much less maneuverable. (That is one among many reasons people learn to fly on Cessna 150s and not on fighter jets.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also not a given that a fighter jet is easier to recover from a stall than an airliner.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="-1" LastEditDate="2015-01-16T21:39:57.207" LastActivityDate="2015-01-16T21:39:57.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11769" PostTypeId="2" ParentId="11760" CreationDate="2015-01-16T15:53:49.393" Score="14" Body="&lt;p&gt;The FAA has an &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/wildlife/faq/&quot;&gt;FAQ&lt;/a&gt; on bird strikes and other wildlife hazards, which includes a (broken) link to their &lt;em&gt;Wildlife Hazard Management at Airports - A Manual for Airport Personnel&lt;/em&gt; &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/wildlife/resources/media/2005_FAA_Manual_complete.pdf&quot;&gt;document&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chapter 9 is called &quot;WILDLIFE CONTROL STRATEGIES AND TECHNIQUES AT AIRPORTS&quot; and includes the following techniques:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Change flight schedules&lt;/li&gt;&#xA;&lt;li&gt;Modify the birds' habitat (food, cover, water)&lt;/li&gt;&#xA;&lt;li&gt;Physically exclude the animals (not so easy with birds)&lt;/li&gt;&#xA;&lt;li&gt;Repel the birds with vehicles, chemicals, sound, visual objects (flags, scarecrows, fake dead animals, lasers)&lt;/li&gt;&#xA;&lt;li&gt;Repel the birds with trained falcons or dogs&lt;/li&gt;&#xA;&lt;li&gt;Shoot nonlethal projectiles at the birds&lt;/li&gt;&#xA;&lt;li&gt;Trap, remove and release the birds at a different location&lt;/li&gt;&#xA;&lt;li&gt;Kill the birds with poison or other means&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The document summarizes the various techniques like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Habitat modifications to minimize food, cover, and water and physical&#xA;  barriers to exclude wildlife are the foundations of wildlife hazard&#xA;  management programs for airports. In addition, an integrated array of&#xA;  repellent techniques is necessary to disrupt normal behavior and to&#xA;  stress hazardous wildlife that attempt to use the airport. These&#xA;  repellent techniques must be used judiciously and backed by real&#xA;  threats to minimize habituation. To this end, lethal control of&#xA;  selected individuals of common species is sometimes necessary to&#xA;  reinforce repellent actions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-01-16T15:53:49.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11770" PostTypeId="2" ParentId="11766" CreationDate="2015-01-16T16:13:43.837" Score="43" Body="&lt;p&gt;The main thing that is required for a stall recovery is just the ability to drop the nose to decrease angle-of-attack and regain airspeed (and, of course, adding power helps, too.) Except in the case of &lt;a href=&quot;https://aviation.stackexchange.com/q/8022/755&quot;&gt;deep stall&lt;/a&gt;, there is still sufficient air flowing over the horizontal stabilizers (and, thus, the elevators) in an airliner to push the nose down during a stall. Furthermore, most airplanes (including nearly all, if not all, airliners) are designed with a center of gravity forward of the center of lift. In normal flight, the air flow over the horizontal stabilizers actually pushes the back of the plane down, which holds up the nose. During a stall, this airflow is reduced (still present, but to a lesser degree,) which will cause the nose to tend to drop by default during a stall condition, even if the pilot (or autopilot) gives no additional control inputs at all. As such, normal (e.g. not fighters or aerobatic planes) will recover from a stall on their own with no additional control inputs, given enough altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As already mentioned, some altitude is also usually required for successful stall recovery. This is because the recovery procedures involve dropping the nose which will briefly result in some descent. The lack of sufficient altitude to recover was the main problem in &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;noreferrer&quot;&gt;Asiana 214&lt;/a&gt;, which crashed just short of the runway in San Francisco. The aircraft was already too low and too slow to recover before the pilots acted. If I remember correctly, they started attempting a go-around only about 7 seconds before the aircraft impacted the seawall. At that point, there was nothing they could do. A small, piston-engine aircraft probably still could have recovered from that situation because piston engines spin up much, much faster than jet engines and could provide the power needed to recover much faster. Pushing the nose down alone would still technically have recovered the plane from the stall condition in this case, but that wouldn't have been very helpful, since it would have meant a nose-first impact into either San Francisco Bay or the seawall, which would obviously have been a much worse outcome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another problem that can happen (though is very, very unlikely on an actual airline flight, but much more likely on cargo flights in airliners) is for the cargo to shift to the point that the center of gravity is too far from where it's designed to be for stall recovery to be possible. This is what happened on &lt;a href=&quot;http://en.wikipedia.org/wiki/National_Airlines_Flight_102&quot; rel=&quot;noreferrer&quot;&gt;National Airlines Flight 102&lt;/a&gt;, a 747 cargo flight departing from Bagram Air Force Base in Afghanistan. Very shortly after takeoff, the cargo shifted to the back of the aircraft, preventing the pilots from being able to lower the nose enough to keep the plane from stalling. It stalled and crashed before ever leaving the property of the airfield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, &lt;a href=&quot;http://en.wikipedia.org/wiki/Longitudinal_static_stability&quot; rel=&quot;noreferrer&quot;&gt;pitch stability&lt;/a&gt; (more precisely known as longitudinal static stability) is what makes an aircraft capable of stall recovery, not maneuverability. While it may seem counter-intuitive to those not familiar with aerodynamics, it's likely actually easier to recover from a stall in an airliner than it is in a fighter (and almost certainly easier to recover in, say, a Piper or Cessna than a jet fighter.) This is because more maneuverable aircraft (such as fighters and aerobatics aircraft) are usually less stable than less maneuverable aircraft like airliners and normal GA aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1418/755&quot;&gt;The answers to this question&lt;/a&gt; give a thorough explanation of stall recovery which I would recommend reading. Its answers apply to how stall recovery is performed in any normal airplane, not just airliners. That question isn't specifically about whether airliners can recover from a stall, though, which is why I didn't mark this one as a duplicate.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-01-16T16:13:43.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11771" PostTypeId="2" ParentId="11746" CreationDate="2015-01-16T17:30:02.883" Score="18" Body="&lt;p&gt;As I said in my comment, I don't think there's any single answer to this question because there are just too many variables and the scenario itself seems a little artificial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, the first thing you can do is negotiate with ATC. Accept the descent instruction but request a return to FL250 as soon as possible. Offer to fly at another altitude (including &lt;em&gt;above&lt;/em&gt; FL250 if possible), or on an alternative route, or with a 10-degree course deviation or anything else that gives ATC options for keeping you at the altitude you want. Of course, there's still no guarantee that the controller will be able to allow it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next thing would be fuel management: depending on the aircraft and your current power settings, you may be able to sacrifice speed in order to gain range. But that might not help either if the end result is still that you won't have the reserves you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If none of those those things are possible then there's no good option except to plan a fuel stop. Declaring an emergency would be an abuse of the system and could lead to an investigation: you have plenty of fuel, just not enough to get where you want to go, and there's no immediate danger to the aircraft. (I read an NTSB ruling where a pilot had repeatedly said &quot;unable&quot; and eventually declared an emergency simply in order to keep on his preferred route. The FAA grounded him, he appealed to the NTSB and lost.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, you hopefully already planned for a possible fuel stop because if the winds are so different at FL210 and FL250 that it makes the difference between making it to your destination or not, that's something you should have found out during flight planning. But even if you didn't, or if the wind just changed suddenly, a diversion for fuel shouldn't be a big deal.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="65" LastEditDate="2015-01-16T17:39:23.723" LastActivityDate="2015-01-16T17:39:23.723" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11772" PostTypeId="2" ParentId="11766" CreationDate="2015-01-16T19:52:18.370" Score="0" Body="&lt;p&gt;Your premise is flawed. It is easier to recover from a stall in a passenger jet than in a fighter jet. An airliner (glide ratio 15:1) is much more buoyant than a fighter (glide ratio 8:1). When a fighter stalls, it drops like a brick and pray it is not in a bad attitude when that happens.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-16T19:52:18.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11773" PostTypeId="2" ParentId="11766" CreationDate="2015-01-16T20:40:40.627" Score="2" Body="&lt;p&gt;It depends on the aircraft type. For instance, &lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-154&quot; rel=&quot;nofollow&quot;&gt;Tu-154&lt;/a&gt; cannot recover from stall unless a special stall-recovery parachute is installed in its tail. The parachute normally is only installed during development testing, and never on the regular airlines.&lt;/p&gt;&#xA;" OwnerUserId="4382" LastActivityDate="2015-01-16T20:40:40.627" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11774" PostTypeId="2" ParentId="11756" CreationDate="2015-01-16T23:44:59.597" Score="15" Body="&lt;p&gt;When war broke out, almost all high-performance military planes on all sides had variable-pitch propellers. Not necessarily &lt;a href=&quot;https://aviation.stackexchange.com/questions/1381/how-does-a-constant-speed-propeller-work/1384?noredirect=1#comment2221_1384&quot;&gt;constant-speed&lt;/a&gt; types, but adjustable nontheless. There was no difference between German and British planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was a difference it was the use of manually-adjustable propeller pitch, which was widely used in German airplanes, versus constant-speed propellers, which found more use in British airplanes. However, both sides had both types of propellers in their fleet, so it is hard to make a generalization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operationally, the manual adjustment gives the pilot more control, but increases workload because the pitch has to be adjusted when flight speed changes. This was less burdensome in bombers, but in fighter aircraft a manual adjustment would keep the pilot busy during dogfights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early types of the aircraft involved did indeed use fixed-pitch propellers, like early versions of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_109_variants#Bf_109_A.2FB.2FC.2FD&quot; rel=&quot;nofollow noreferrer&quot;&gt;Me-109 A and B&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Hurricane#Variants&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawker Hurricane Mk.I&lt;/a&gt;. By 1939, both types had long since converted to variable-pitch propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older airplanes with fixed-pitch propellers were still used for training or liaison, but not near the front lines. Exceptions are aircraft like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Polikarpov_Po-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Polikarpov Po-2&lt;/a&gt; which was used for night attacks until the Korean war. It had such a limited speed range that a variable-pitch propeller would not had made sense.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-01-17T12:49:17.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11775" PostTypeId="1" AcceptedAnswerId="11798" CreationDate="2015-01-17T02:11:58.590" Score="3" ViewCount="261" Body="&lt;p&gt;Let us assume we have a localizer (identifier I-STK) transmitting at 110.10MHz and a matching glideslope at 334.40MHz.  If a device aboard an aircraft tracking the I-STK ILS were to emit an unmodulated interfering carrier on either of those frequencies that is then picked up by the ILS receiver's antennae, with enough power to render the LOC or G/S signal unreceivable, would the pilots see a consistent wrong indication, erratic/wildly changing indications, or a FAIL flag?  Would the behavior under this circumstance differ between glass and round-dial aircraft cockpits?  Also, would the ILS Morse identifier be rendered unreceivable before or after the cockpit indications fail?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="19" LastEditDate="2017-01-23T19:07:19.373" LastActivityDate="2017-01-23T19:07:19.373" Title="What is the behaviour of ILS when there is an unmodulated interfering carrier signal?" Tags="&lt;safety&gt;&lt;avionics&gt;&lt;ils&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11776" PostTypeId="1" AcceptedAnswerId="11788" CreationDate="2015-01-17T02:20:51.720" Score="10" ViewCount="1590" Body="&lt;p&gt;Fixed-wing aircraft (just about all of them!) have &lt;a href=&quot;https://aviation.stackexchange.com/questions/2720/what-are-these-things-hanging-off-the-trailing-edge-of-the-wing/2721#2721&quot;&gt;static wicks&lt;/a&gt; to dissipate static charge buildups before they can become obnoxious or shocking.  Are helicopters fitted with them? &lt;a href=&quot;https://aviation.stackexchange.com/a/9360/3825&quot;&gt;This answer&lt;/a&gt; suggests they are not.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-19T17:18:19.280" Title="Do helicopters use static wicks?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;static-electricity&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11778" PostTypeId="2" ParentId="11766" CreationDate="2015-01-17T04:02:38.557" Score="0" Body="&lt;p&gt;Stalls occur more frequently than you may think. A stall is basically when there is no lift being generated due to lack of air moving past the wing. In fact, when an airliner takes a somewhat steep turn, the outer edge of the wing starts stalling before the inner tip of the wing due to a slight tilt in the airliners wings, called a wash-in wash-out. This way, the pilot still has some control of the aircraft in order to correct it. So yes, the answer is that an airliner can indeed recover from a stall. In situations where the stall angle is too high and the speed is too low, the airplane may not be able to recover, as it most likely would be falling down like a rock, but majority of the time, given enough altitude and speed, it is possible to correct the stall. There have been many cases where pilots have recovered from stalls without crashing.&lt;/p&gt;&#xA;" OwnerUserId="6884" LastActivityDate="2015-01-17T04:02:38.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11779" PostTypeId="2" ParentId="11766" CreationDate="2015-01-17T05:16:34.293" Score="3" Body="&lt;p&gt;The Air France tragedy was partly that according to the flight data/voice, and some other impingent facts of note.  Very high altitude, near the limit of the type for both altitude and air speed (actual air speed ~ 250 kts !!), also due to high air temp, less power, and non-stall velocity/AOA envelope was then very small.  The pilot at the controls saw (typical for equatorial mid atlantic nights) severe weather ahead, and wanted to get on top of it.  He really wanted altitude. Then the pitots iced, and he was suddenly a fish out of water, and he started to try to climb more, putting it into a stall regime, but he didn't seem to realize.  They got into worse shape (up to 45 deg bank excursions) and the Captain was awakened and came to the flight deck, but apparently never touched a control. in just a short time, the ice cleared, the pitots were good. the plane that hit the water was a 100% functional machine. Then the problem seemed to be language - although all French, when co pilot suggested he get &quot;more&quot; he meant airspeed, but didn't say put the nose down. The first pilot continued to try to put the nose up (&quot;more altitude&quot;. those two pilots went back and forth, verbally and override=preempting control of the control system from each other. Mean while, the flight deck annunciator for &quot;STALL&quot; had shut it self off after a while cuz it was given an &quot;impossible&quot; angle of attack as input, and gave up.  It was so far nose up, the software disregarded it as a broken signal.  Speculation is this reinforced the &quot;climbing&quot; pilots conclusions. This all went on as it plowed thru the air for several minutes, from +40K ft to the predicted last chance at 13Kft, when in theory, they could have still gotten the nose down enough for lift velocity then pull up before the wave tops that killed them. They never began a real stall recovery (other than to NOT roll over into an inverted dive or spin).  They continued to argue and be confused, and unmanaged.&#xA;My source for all of this was a good, detailed treatment in VOGUE, a few months ago.&#xA;The plane most certainly could have been flown home, but not in boxes and bags, as it was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was capable of recovering, given the most altitude any pilot might ever get to start an emergency.  I sit next to a SW developer from the 777 project (did flap control), and he was bemoaning the fact ...yes, Airbus went too far in expecting lesser trained crews to save the plane via auto systems, vs the perception that Boeing style designs were more likely to let a good pilot know what the plane is doing, and not doing, and get on with flying it.&lt;/p&gt;&#xA;" OwnerUserId="6885" LastActivityDate="2015-01-17T05:16:34.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11780" PostTypeId="1" CreationDate="2015-01-17T08:14:23.980" Score="0" ViewCount="383" Body="&lt;p&gt;What are the differences between &lt;strong&gt;American major &lt;a href=&quot;http://en.wikipedia.org/wiki/Major_airlines_of_the_United_States&quot; rel=&quot;nofollow&quot;&gt;mainline passenger&lt;/a&gt; airline&lt;/strong&gt; scheduling policies?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably, each airline runs a model or optimization problem for determining&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;where&lt;/em&gt; (markets/airports),&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;when&lt;/em&gt; (timing of the flights throughout the day), and&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;how many seats&lt;/em&gt; (plane capacity).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there any &lt;strong&gt;specific examples&lt;/strong&gt; of different scheduling &lt;strong&gt;policies, methods, or algorithms&lt;/strong&gt; among airlines - within the context of each airline doing the best it can to match its schedule to market demand, according to its business plan and strategy?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-01-19T03:47:17.187" LastActivityDate="2015-01-19T03:47:17.187" Title="Airline flight scheduling method differences" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;airlines&gt;&lt;flight-schedules&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-01-17T23:39:29.237" ContentLicense="CC BY-SA 3.0" />
  <row Id="11781" PostTypeId="2" ParentId="11766" CreationDate="2015-01-17T08:15:39.567" Score="0" Body="&lt;p&gt;Yes an airliner can recover from a stall. The question of the pilots abilities to recover from that stall come into play. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most modern airliners (Boeing, Airbus, Candair) install &quot;stick shakers/ stick pushers,&quot; which are designed to alert the pilot to a stall and attempt a recover from the stall before it happens. If the pilot were to push the airliner into a stall, there is a possibility that the jet would not recover &quot;nose down&quot; as previously stated because of the aerodynamics of an airliner. This requires a stalled horizontal tail surface as well; a highly unlikely situation.&#xA;In this case, if a tail-down command occurred, the pilot would need to press full deflection on the ailerons, possibly supported by spoilers, to either side to bring the aircraft over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pushing forward in a stall situation would result in one of two scenarios: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;the airflow over the horizontal stabilizers would not be sufficient to bring the nose down and the stall would continue, &lt;/li&gt;&#xA;&lt;li&gt;the tail gets lifted, the angle of attack decreases and the airplane recovers. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So with the aileron at full deflection the aircraft would roll and bring the nose down, and once level or below the horizon the pilot could then begin to gain airspeed and roll the aircraft out of the high roll angle and begin a normal stall recovery with positive G-forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: According to Boeing, my previous comment is not totally supported. This answer is based on a &quot;nose high, wings level&quot; situation. Per Boeings website, they state- &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;If normal pitch control inputs do not stop an increasing pitch rate, rolling the airplane to a bank angle that starts the nose down should work. Bank angles of about 45 degrees, up to a maximum of 60 degrees, could be needed. Unloading the wing by maintaining continuous nose-down elevator pressure will keep the wing angle of attack as low as possible, making the normal roll controls as effective as possible. With airspeed as low as stick shaker onset, normal roll controls -- up to full deflection of ailerons and spoilers -- may be used. The rolling maneuver changes the pitch rate into a turning maneuver, allowing the pitch to decrease. Finally, if normal pitch control then roll control is ineffective, careful rudder input in the direction of the desired roll may be required to induce a rolling maneuver for recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only a small amount of rudder is needed. Too much rudder applied too quickly or held too long may result in loss of lateral and directional control. Because of the low energy condition, pilots should exercise caution when applying rudder.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully this is the support that was asked for. I personally came across the aforementioned answer during aerodynamics class in college. &lt;/p&gt;&#xA;" OwnerUserId="6888" LastEditorUserId="1961" LastEditDate="2015-01-18T19:59:55.427" LastActivityDate="2015-01-18T19:59:55.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11782" PostTypeId="2" ParentId="3428" CreationDate="2015-01-17T09:48:18.470" Score="10" Body="&lt;p&gt;&lt;strong&gt;Q: Do box wings suffer from induced drag the same way as normal wings?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A: Yes and no.&lt;/strong&gt; Box Wing aircraft will suffer from induced drag the same as any aircraft will, if they are heavier-than-air vehicles and are using their wings to fly. Induced drag is a function of finite span loading, and moderated by various ways to improve design efficiency at a given span loading. Thus the amount of drag, and the way it is created and avoided, differs for a boxwing and a monoplane of the same span. Today this topic of induced drag includes completely different definitions than what was taught in seminal references on the subject. Even if one is talking about the same thing, the topic will hear arguments from two different camps: those who adhere to representative mathematics, and those who focus on the non-Cartesian, non-textbook actual physics on a case-by-case basis. It's quite fair to say that the former are more vocally opinionated than the latter, for the latter know less until later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The job of a wing is to efficiently push and pull air downward as it moves forward. That action causes both a Newtonian reaction and a Bernoulli pressure differential, resulting in lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making lift this way causes the nearby air to also be affected, as a time-dependent secondary result. It has to 'fall into the descending trough of air' that the wings displaced downward. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This secondary movement causes (completely unavoidable) rotational movements in the &quot;wake&quot; zone between air directly moved by the wings and the nearby stationary air, thereby involving more air mass than the plane needed to move just to get the lift it needed. (The momentum difference is quite literally the induced drag, although we usually teach it in ways more related to how induced drag is visualized and computed in 2-D. Other answers posted here illustrate this in conventional terms.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Induced drag and wake vortex CANNOT be eliminated&lt;/strong&gt; for a lifting wing system of any kind. However, most aircraft wing designs allow something else to happen that greatly increases this cost of &lt;strong&gt;making lift with a finite wingspan:&lt;/strong&gt; they let &lt;em&gt;high pressures under the wing&lt;/em&gt; be 'too close' to the &lt;em&gt;low pressures above the wing&lt;/em&gt; for the amount of &lt;strong&gt;pressure difference&lt;/strong&gt; that has developed in flight. If a high differential pressure exists at a wing tip, a strong, tornado-like vortex will form there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Allowing any strong gradient to form between low pressure and high pressure&lt;/strong&gt; will cause air to move toward the low pressure at a high velocity, if it can. Drag increases exponentially with the velocities imparted to the air, therefore designers use a variety of approaches to keep this equalization from happening quickly. The slower it happens, the less kinetic energy is imparted to the air by the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is where Boxwings have a totally different way of reducing the induced drag, compared to a normal wing: &lt;em&gt;they put a wall up&lt;/em&gt; between the low pressure above the wing, and the higher pressure everywhere else. The 'wall' can be taller than a winglet, because it has a wing above to help resist the forces that push on it from the side. At that upper wing connection, the wall-like vertical surface of a boxwing likewise &lt;strong&gt;stands between&lt;/strong&gt; the higher pressure under the wing, and the lower pressure everywhere else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a designer does a good job with this idea (many do not), both the biplane wing surfaces and the vertical surfaces of the boxwing system will moderate the velocity of gradient-induced airflows by acting against the undesirable flows in 3-D space. They become more effective in this with greater vertical spacing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The easier and more effective way to reduce the induced drag is simply to increase the wingspan, or reduce the vehicle weight. As a wing gets longer, the portion of the lift each unit of the wing needs to make is reduced, meaning that it will have a lower pressure differential between the upper and lower surfaces. Best practice calls for this differential to be minimized at the tip, so the gradient is weakened. The result then is that a weaker pressure gradient and a longer distance between low and high pressures will keep the equalization velocities down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as an aircraft gets heavier or goes faster, this approach becomes first very expensive, then impossible. Material strength limitations put definite limits on the wingspan of conventional aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surprisingly, box wings fare no better... perhaps worse. What appears to be a structural advantage actually merely concentrates the bending forces, generated by each wing, into the corners of the box. Making them strong enough quickly becomes excessively heavy. Therefore, a box wing aircraft should, like a biplane, have a shorter span than a monoplane of equivalent induced drag. Its span efficiency bears greater fruit among short span designs, than where wingspan can be increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One might think that this advantage would then bear fruit indirectly, through speed. The faster an aircraft flies, for a given span loading, the less induced drag it will make. In fact, at high indicated airspeeds, induced drag becomes a small component of total drag. However, other aspects of box wing designs seem to have impeded high-speed boxwing solutions; notably stability; and &quot;interference drag.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a box wing design, there is a &lt;strong&gt;forward set of lifting wings&lt;/strong&gt;, and an &lt;strong&gt;aft set of lifting wings&lt;/strong&gt;. In high speed flight this configuration cannot respond as stably or as quickly to certain conditions as a wing with a (downward-lifting) tail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When set up as a tandem-lifting wing arrangement without such a stabilizer, as is typical of modern versions, &lt;strong&gt;boxwings have to balance at their combined center of upward lift&lt;/strong&gt;, rather than ahead of it like conventional aircraft do, thanks to the stabilizing influence of a tail pushing in the opposite direction. This limitation and tandem-wing stall behaviors place challenging, &lt;strong&gt;inherent demands&lt;/strong&gt; on boxwing designs that constrain their success at higher flight speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted above, they also create interference drag. This type of drag can be hard to predict and is also widely misunderstood. In practice, the inherent, 3-D interference drag of a boxwing aircraft design greatly reduces the 2-D theoretical advantage of the configuration toward obtaining induced drag benefits. This is why they are not at all like &quot;normal wings.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in the original post, there is a new aircraft configuration that is often mistaken for a box wing design. However, it is nothing like them. It's called a box-tail or double boxtail configuration. I am the designer of the &lt;strong&gt;Synergy double boxtail aircraft,&lt;/strong&gt; which is the first such aircraft to be developed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These somewhat disappointing attributes of the otherwise logical box wing configuration were at the heart of matters during the long period of Synergy's development. It was my desire to utilize high span efficiency and laminar flow in a high speed aircraft design, while avoiding high speed landings and unpredictable, unstable behaviors at low speeds. A video of a 25% scale model in flight and a basic overview can be seen at &lt;a href=&quot;http://www.synergyaircraft.com&quot; rel=&quot;noreferrer&quot;&gt;synergyaircraft.com&lt;/a&gt;. A post on the topic of boxwings can be found there as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information regarding span efficiency and non-planar configurations, Ilan Kroo has published very thorough overviews of the subject. The graphic below is adapted from one appearing in his papers. It shows how induced drag can be fought in 3-D space by moving away from a flat, planar wing into the vertical dimension. Synergy builds that understanding further, into the longitudinal and time dimensions, in accord with the concepts advanced first by George C. Greene while at NASA Langley. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rtju2.jpg&quot; alt=&quot;Span efficiency for non-planar configurations&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="6889" LastEditorUserId="6889" LastEditDate="2017-06-25T04:31:52.117" LastActivityDate="2017-06-25T04:31:52.117" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11783" PostTypeId="2" ParentId="11766" CreationDate="2015-01-17T10:47:20.170" Score="5" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Can a large passenger aircraft recover from a stall?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;Yes&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=4WuPoVjOXLY&quot; rel=&quot;noreferrer&quot;&gt;Airbus stall training video&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Here's what &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_03/textonly/fo01txt.html&quot; rel=&quot;noreferrer&quot;&gt;Boeing &amp;amp; Airbus say&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;this article was written jointly by Airbus, Boeing Commercial Airplane Group, and Douglas Products Division. The article focuses on Airbus and Boeing airplanes that do not have electronic flight controls, commonly known as fly-by-wire. However, when a fly-by-wire airplane is in a degraded control law (mode), the recovery techniques are appropriate.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;An airplane stall is characterized by any one (or a combination) of the following conditions:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Buffeting.&lt;/li&gt;&#xA;&lt;li&gt;Lack of pitch authority.&lt;/li&gt;&#xA;&lt;li&gt;Lack of roll control.&lt;/li&gt;&#xA;&lt;li&gt;Inability to arrest descent rate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;These conditions are usually accompanied by a continuous stall warning. A stall must not be confused with the stall warning that alerts the pilot to an approaching stall. Recovery from an approach to stall is not the same as a recovery from an actual stall. An approach to stall is a controlled flight maneuver; &lt;strong&gt;a stall is an out-of-control, but &lt;em&gt;recoverable&lt;/em&gt;, condition&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;STALL RECOVERY.&lt;br /&gt;&#xA;In all upset situations, it is necessary to recover from a stall before applying any other recovery actions. To recover from the stall, angle of attack must be reduced below the stalling angle. &lt;strong&gt;Nose-down pitch control must be applied and maintained until the wings are unstalled&lt;/strong&gt;. Under certain conditions, on airplanes with underwing-mounted engines, it may be necessary to reduce some thrust in order to prevent the angle of attack from continuing to increase. Once unstalled, upset recovery actions may be taken and thrust reapplied as needed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(my emphasis).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;A Bloomberg article: &lt;a href=&quot;http://www.bloombergview.com/articles/2012-07-22/does-your-airline-pilot-know-how-to-escape-from-a-stall-&quot; rel=&quot;noreferrer&quot;&gt;Does Your Airline Pilot Know How to Escape From a Stall?&lt;/a&gt; says&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When planes do crash, the No. 1 cause is pilot loss of control. From 2001 to 2010, 1,756 people died in 20 such disasters. About half of these accidents involved aerodynamic stall,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Although this article suggests more training of pilots in stall recovery, the emphasis is properly on preventing a stall.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-17T11:18:53.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11784" PostTypeId="2" ParentId="3382" CreationDate="2015-01-17T12:02:34.123" Score="13" Body="&lt;p&gt;Short answer: &lt;strong&gt;In all cases these are not winglets, but fins.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;Winglets are worse than an equal span extension&lt;/a&gt; and are only used if span should not increase:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;for limiting the wing's root bending moment, or&lt;/li&gt;&#xA;&lt;li&gt;for size limitations&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Putting them on the tail surface would not help to limit the wingspan: The horizontal tail can easily grow and still be much smaller than the wing. There is no single case where winglets on a horizontal tail would have made sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you see and might interpret as winglets are actually additional fins. They stay in the general area of the vertical tail, so they do not increase the sideslip-induced rolling moment, and they do not increase aircraft height. But they help to improve lateral stability, which had been worsened by a configuration change. Example pictured below: The &lt;a href=&quot;http://en.wikipedia.org/wiki/Beechcraft_1900&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beech 1900&lt;/a&gt;, a derivative of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Beechcraft_Super_King_Air&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beech Super King Air&lt;/a&gt;. The fins below the fuselage could not grow any bigger without risking ground contact during rotation, and the small stability deficit did not justify the development of a new tail section. So the fins were added where they would cause the least amount of trouble. Obviously, aesthetics were not considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rdY5A.jpg&quot; alt=&quot;Beechcraft 1900 commuter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the small planes at the bottom of the vertical tail: The same trick was used to avoid increasing the size of the horizontal tail. It could be argued that the horizontal tail of the Beech 1900 is a double decker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no, those horizontal fins are not &quot;fuselage winglets&quot;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;So-called &quot;winglets&quot; on the tail of the DA42&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;That is also the reason why the &quot;winglets&quot; are so much bigger on the MPP version of the DA42: They offset the destabilizing effect of the camera pod. The canted tips of the original DA42 are working like an anhedral and create a compensating positive rolling moment for the vertical tail's negative sideslip-induced rolling moment. Ideally, the whole horizontal tail would have anhedral, but it was preferred to keep the elevator hinge line straight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-07T20:21:32.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11786" PostTypeId="1" AcceptedAnswerId="11804" CreationDate="2015-01-17T14:43:37.750" Score="9" ViewCount="8386" Body="&lt;p&gt;Are there any drawbacks if someone who is a fixed-wing pilot, learns to fly a helicopter, or vice-versa? Specifically, are there instinct actions in one category that are dangerous in the other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this differ if someone is experienced in one category (e.g. 1000+ hours), versus a student learning both within a short period of time (e.g. less than 6 months in between)?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="65" LastEditDate="2015-03-20T19:59:26.300" LastActivityDate="2015-03-20T19:59:26.300" Title="What are the drawbacks of being a helicopter and fixed-wing pilot at the same time?" Tags="&lt;helicopter&gt;&lt;fixed-wing&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11787" PostTypeId="1" AcceptedAnswerId="11790" CreationDate="2015-01-17T14:49:00.337" Score="14" ViewCount="2757" Body="&lt;p&gt;I was watching Mayday S11E02 about &lt;a href=&quot;http://en.wikipedia.org/wiki/West_Caribbean_Airways_Flight_708&quot;&gt;West Caribbean airways flight 708&lt;/a&gt; and the pilots turned off the de-icing system partway through the flight. It's not why it crashed, but I was curious as to if there was any disadvantage to having the de-icing system on.&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="609" LastEditDate="2015-01-17T15:15:43.007" LastActivityDate="2015-01-20T05:41:48.073" Title="Is there any disadvantage to having the de-icing system on?" Tags="&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;accident-investigation&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11788" PostTypeId="2" ParentId="11776" CreationDate="2015-01-17T16:30:31.493" Score="10" Body="&lt;p&gt;Static wicks are mostly found on aircraft that fly in &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;nofollow&quot;&gt;Instrument Meteorological Conditions&lt;/a&gt; because static charges typically build up when flying in precipitation, not in clear air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you won't find static wicks on helicopters that are certified only for visual conditions, like the R-22, R-44, Bell 206, piston Enstroms, etc., but you will find static wicks on helis that are certified for IFR.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Static wicks] are used on aircraft to allow the continuous&#xA;  satisfactory operation of onboard navigation and radio communication&#xA;  systems during precipitation (p-static) conditions. &lt;strong&gt;Precipitation&#xA;  static is an electrical charge on an airplane caused by flying through&#xA;  rain, snow, ice, or dust particles&lt;/strong&gt;. When the aircraft charge is great&#xA;  enough, it discharges into the surrounding air. &lt;a href=&quot;http://en.wikipedia.org/wiki/Static_discharger&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Static_discharger&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-19T17:18:19.280" LastActivityDate="2015-01-19T17:18:19.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11790" PostTypeId="2" ParentId="11787" CreationDate="2015-01-17T16:38:57.360" Score="17" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/West_Caribbean_Airways_Flight_708#Accident&quot; rel=&quot;noreferrer&quot;&gt;wikipedia article already linked in the question&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The system uses power from the engines, thus reducing their maximum performance. With the anti-ice system on, the highest altitude at which the overloaded aircraft could fly – without stalling – was reduced to 31,900 feet (9,700 m).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The de-icing system on most turbine aircraft (including MD-82 involved in that accident) uses bleed air from the engines, that is it extracts some air from behind the (low pressure stage of the) compressor. This air is therefore not ejected from the nozzle and not producing thrust, so the thrust is reduced. Or fuel flow rate increased if thrust levers are advanced to compensate, provided the engines are still below their maximum permitted thrust setting. Either way fuel consumption per mile increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compressing air increases it's temperature, so this pressurized air is simply blown through tubes under the critical surfaces. There are other uses of bleed air, mainly pressurization and air-conditioning, but turning on deicing increases it's consumption significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And note that this switching de-icing off and on was part of the accident sequence. It was only because they turned de-icing off that they were able to climb to FL330 in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also often not allowed to use de-icing when outside temperature is higher than some value because the heated surfaces could overheat.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-01-20T05:41:48.073" LastActivityDate="2015-01-20T05:41:48.073" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11791" PostTypeId="1" AcceptedAnswerId="11796" CreationDate="2015-01-17T16:57:46.987" Score="10" ViewCount="813" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=4Y9-wPkV4ls&quot; rel=&quot;noreferrer&quot;&gt;Air Crash Investigation: M1 Plane Crash (S14E01)&lt;/a&gt; motivated this question, the relevant timestamps for which I greened. Neither the audio or picture below (in which the hands are hiding the front of the head) explicitly resolves: For maximal safety, in the 2nd suggested brace position (on the right, timestamped at 42.10), should the head touch or rest on the seat in front?&lt;br&gt;&#xA;I know nothing of physics or aerodynamics, so please explain in as simple English as possible. The original video appears too dark, so I did enhance the originals (using Gamma Correction):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aejVr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="22550" LastEditDate="2019-01-06T19:52:47.470" LastActivityDate="2019-01-06T19:52:47.470" Title="In this 2nd brace position, should your head lean against the seat in front?" Tags="&lt;emergency&gt;&lt;passenger&gt;&lt;emergency-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="11792" PostTypeId="1" CreationDate="2015-01-17T16:58:57.723" Score="4" ViewCount="209" Body="&lt;p&gt;Let's say I'm on an SVFR clearance and the flight and reported ground visibility deteriorates less than 1 mile, what happens?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-01-19T14:50:25.977" LastActivityDate="2015-01-19T14:50:25.977" Title="Can an airplane on an SVFR clearance land when visibility is less than 1 mile?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;special-vfr&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11793" PostTypeId="2" ParentId="11792" CreationDate="2015-01-17T17:00:19.420" Score="5" Body="&lt;p&gt;If the pilot is on an SVFR clearance, the weather inside the surface area deteriorates below 1 mile visibility, and the pilot has the airport in sight, he can inform the controller that he has the field in sight and will be cleared to land. The pilot is responsible for continuing to the airport or exiting the surface area in order to remain visual.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE− Clear an aircraft to land at an airport with an operating&#xA;  control tower, traffic permitting, if the pilot reports the airport in&#xA;  sight. The pilot is responsible to continue to the airport or exit the&#xA;  surface area. 14 CFR Section 91.157 prohibits VFR aircraft (other than&#xA;  helicopters) from landing at any airport within a surface area when&#xA;  flight visibility is less than 1 mile. A pilot could inadvertently&#xA;  encounter conditions that are below SVFR minimums after entering a&#xA;  surface area due to rapidly changing weather. The pilot is best suited&#xA;  to determine the action to be taken since pilots operating under SVFR&#xA;  between sunrise and sunset are not required to be instrument rated,&#xA;  and the possibility exists that flight visibility may not be the same&#xA;  as ground visibility. 14 CFR Section 91.3 authorizes a pilot&#xA;  encountering an inflight emergency requiring immediate action to&#xA;  deviate from any rule of 14 CFR Part 91 to the extent required to meet&#xA;  that emergency. Flight into adverse weather conditions may require the&#xA;  pilot to execute the emergency authority granted in 14 CFR Section&#xA;  91.3 and continue inbound to land. &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Control Handbook, 7−5−4&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-17T17:00:19.420" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11794" PostTypeId="2" ParentId="11780" CreationDate="2015-01-17T17:10:19.440" Score="2" Body="&lt;p&gt;There are many academic papers available for &lt;em&gt;general airline scheduling&lt;/em&gt; topics. Airline flight schedule planning is a huge topic, existing within the more general field of Operations Research. The models and algorithms used are not simple by any means, and thus there could exist &lt;em&gt;many kinds&lt;/em&gt; of differences between the methods used by each of the different airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering such models are part of how airlines gain a competitive advantage, specific airline methods, at least for now, are &lt;strong&gt;proprietary information&lt;/strong&gt;.  Perhaps this will not always be the case, but it would take a change in the  way the airline industry operates for this type of information to be publicly available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the data &lt;em&gt;about the output&lt;/em&gt; of those models are freely available, collected by the U.S. Government (see the &lt;a href=&quot;http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/subject_areas/airline_information/index.html&quot; rel=&quot;nofollow&quot;&gt;Bureau of Transportation Statistics&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically, one could mine the available data to reverse-engineer some differences, but these will be theories at best.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-01-17T17:10:19.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11795" PostTypeId="2" ParentId="11786" CreationDate="2015-01-17T17:19:41.623" Score="10" Body="&lt;p&gt;In case of an engine failure, the fixed wing pilots natural reaction is to push forward to lower the nose, then look for the correct glide airspeed. A helicopter pilot in most engine failures should pull back (although not agressively) to load the disc and restore, or increase rotor RPM.  Maintaining rotor RPM is the only way to get to the ground safely so flaring is an instinctive reaction trained in.  You don't look for airspeed or rotor RPM.  You dump the collective and flare, then have a look at airspeed and RPM.  Pushing forward will reduce rotor RPM which in some flight phases and some helicopters might not kill you but in many helicopters at altitude may well kill you.  In addition, a stall buzzer will prompt the fixed wing pilot to push the stick forward and increase power, which in a helicopter means pulling the collective.  In a helicopter the low rotor RPM buzzer sounds just like a stall warning but pushing the stick forward and pulling the collective will almost certainly kill you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another action that has to be instinctive is to stick in a boot full of right pedal (counter clockwise rotor) which is totally alien to a single engine fixed wing pilot in an engine failure and completely the opposite of what a twin engined fixed wing pilot might do, who will naturally &quot;step on the failed engine&quot;.  In a helicopter, that can get you into a very bad attitude rapidly from which it might be impossible to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Negative G in an aircraft is not a problem. In a 2 bladed helicopter, you must gently pull back to reload the disc.  Pushing forward has a real risk of a blade chopping off the tail or hitting the canopy. It might also cause &quot;mast bumping&quot; which can cause the rotor to separate from the aircraft.  Too many helicopter pilots have been killed this way. Most helicopter pilots avoid -ve G.  The main point here is that you do not push the stick forward to level out from a climb.  The instinctive reaction for a helicopter pilot is to to pullback as soon as they feel the slightest hint of rising out of their seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a helicopter, to accelerate, you push the stick forward then increase power to maintain altitude or climb.  In an aircraft, you increase power, then push the stick forward to maintain altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A running landing, and not a hover landing, requires you to push the stick forward to level the skids.  A fixed wing tricycle gear pilot wants to pull the stick back to flare which again, might chop off the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keeping trim (balance) is a function of power and not direction of turn.  It is perfectly possible to make a properly executed balanced turn in a helicopter with the opposite pedal pushed in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters can slow down with a nose down attitude and you take off by pushing the stick forward to accelerate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are others which I've forgotten but I think these are the main things and, most importantly, as I've shown, trying to fly a helicopter like a fixed wing can be deadly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, flying helicopters is very different to flying fixed wing and you need different responses which need to be intuitive, especially in emergencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My gut reaction response is that it is easier to transition from helicopter to fixed wing and that the lower time pilots will find it easier because the years of experience and muscle memory are not there.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-18T21:19:56.763" LastActivityDate="2015-01-18T21:19:56.763" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11796" PostTypeId="2" ParentId="11791" CreationDate="2015-01-17T17:37:19.647" Score="11" Body="&lt;p&gt;The head should be against the seat in front of you. The reason is that if the plane crashes, your head and upper body will be thrown forwards until they hit something. If you're in a normal sitting position, your head will be moving pretty quickly by the time it smashes into the seat in front of you, leading to serious injury or death. Moreover, as your torso and head are moving forwards in an uncontrolled way, you can get injured by your head essentially flopping around. Since your head is going to end up against the seat in front of you anyway, putting it against that seat before the crash means it doesn't smash into it during the crash, and that it's not flopping around on its way to the seat.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-01-17T17:37:19.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11797" PostTypeId="2" ParentId="11787" CreationDate="2015-01-17T17:38:19.570" Score="7" Body="&lt;p&gt;It depends on the type of de-icing system.&#xA;A jet like the MD-82 on that flight will use bleed air from the engines which supplies TAI (thermal anti ice) for engine nacelles and wings. That extra bleed air taken from the engines lowers their power output and decreases the fuel economy. If you are limited by EGT for available power, turning on anti-ice is going to degrade your climb performance. &#xA;Likewise, on a descend using anti-ice might require running the engines higher than flight idle to supply enough air, which effects the descend path and lowers fuel economy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, on a jet with thermal anti-ice, it's not exactly dangerous to run the anti-ice when it's not needed, it just lowers your performance and economy a bit. If you on the other hand need every little bit of power you can get (following an engine failure for example) turning off anti-ice might give you just that bit of power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On certain, mostly propeller powered aircraft, however there's a different system for de-icing (note that it's de-ice, not anti-ice) that works with inflatable boots on the leading edge of the wings and/or horizontal stabilizer.&#xA;The idea is that you let a sheet of ice accumulate on the de-icing boots, and then inflate them using a compressor, which breaks the sheet of ice that is then blown away. Turing on the de-icer will normally cycle the compressor so it inflates and deflates the boots in regular intervals to break off accumulating ice. Turning on those de-icing boots too early will accomplish nothing, because the boots can only break off sufficiently hard ice. Some manuals even consider turning on the boots too early (less then 1/4&quot; of ice accumulation) harmful, as the ice might not be hard enough to break off cleanly and instead stick to the boot. This advise is found in some older manuals, I do not have any hard evidence if this is still considered best practice or if it is an old wive's tale. &lt;/p&gt;&#xA;" OwnerUserId="577" LastActivityDate="2015-01-17T17:38:19.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11798" PostTypeId="2" ParentId="11775" CreationDate="2015-01-17T19:35:36.190" Score="4" Body="&lt;p&gt;If an invalid signal is received, then it must be modulated since it is only by measuring the modulation, that the receiver knows if the signal is valid and where it is relative to the localiser and glideslope. An unmodulated carrier on the same frequency is additive.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An unmodulated carrier on a different frequency will not affect the receiver (ignoring possible harmonics of course). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that if you could increase the power enough, an unmodulated signal might cause the signal to noise ratio to drop so low that the failure flag would show.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-21T23:11:05.983" LastActivityDate="2015-01-21T23:11:05.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11800" PostTypeId="2" ParentId="11748" CreationDate="2015-01-17T22:02:07.657" Score="-4" Body="&lt;p&gt;There is no limit, really. The question is not whether the controller would &quot;start making mistakes&quot;, it is how much attention would the controller give to each plane, which just grows less and less the more aircraft there are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the tower goes completely dark, the pilots will self-organize and land themselves. The controller is just there to make the process easier and safer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes controllers do ignore you when they get busy with something else and what happens is you end up flying really LONG downwinds, so by the time the controller gets around to you, you turn onto a 5-mile final or something like that. If the controller completely blows you off, you can leave the pattern, do a U-turn, come around and re-enter the pattern to try again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a big airport with a lot of commercial aircraft, if the controllers started to go AWOL the pilots would probably just stack themselves up on the instrument track, and even start landing themselves if the tower became totally unresponsive. To do this, they just tell the other pilots where they are and their position in the queue (&quot;Lufthansa One Echo Echo downwind for two four left, number three behind the Embraer&quot;, etc).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-17T22:02:07.657" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11801" PostTypeId="1" CreationDate="2015-01-18T01:06:34.097" Score="5" ViewCount="1447" Body="&lt;p&gt;Why does lift over drag decrease with AoA past the optimum AoA?  Is it because the backwards vector for a given lift force on the wing is now larger for a given air particle compared to lower AoA?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a single air particle interacting with the wing at higher vs lower AoA does the higher AoA cause a larger change in the velocity of the air particle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there other factors involved?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="2923" LastEditDate="2015-01-18T14:35:27.407" LastActivityDate="2016-07-15T09:17:51.060" Title="What is the fundamental physics behind L/D decreasing as AoA increases beyond the optimal point?" Tags="&lt;wing&gt;&lt;lift&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11802" PostTypeId="2" ParentId="11801" CreationDate="2015-01-18T03:02:17.403" Score="9" Body="&lt;p&gt;The &lt;em&gt;fundamental&lt;/em&gt; reason is that at high enough AoA, the lift becomes zero -- certainly no later than an AoA of 90°! At that point L/D is zero (there'll be lots of drag). So somewhere between 0° and 90° there will be an AoA with the highest L/D, and that is &lt;em&gt;by definition&lt;/em&gt; the optimum AoA. Slightly beyond that angle there's nothing for the L/D to &lt;em&gt;do&lt;/em&gt; except decrease, because if it didn't, the angle we're beyond wouldn't be the optimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if you were asking why &lt;em&gt;that particular&lt;/em&gt; angle is optimal for a given airfoil, we would have to go into aerodynamics and boundary layers and whatnot. It's not merely about what happens to the molecules that (try to) hit the underside of the wing, but at least as much about how well the molecules &lt;em&gt;above&lt;/em&gt; the wing can be convinced not to hit it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that above the optimal AoA, until the critical (stall) angle, the lift generated still &lt;em&gt;increases&lt;/em&gt; with increasing AoA -- it's just that in this range drag increases &lt;em&gt;faster&lt;/em&gt; than the lift does.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-01-18T15:01:45.490" LastActivityDate="2015-01-18T15:01:45.490" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11803" PostTypeId="2" ParentId="11801" CreationDate="2015-01-18T08:20:21.173" Score="4" Body="&lt;h2&gt;Local speed at low angle of attack&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At low angle of attack, the oncoming air hits the airfoil right at the tip of the leading edge. There is not much of curvature to negotiate before the long stretch with little curvature behind the nose follows. In order to change its flow path quickly, the air molecule must flow in a high pressure gradient, and this gradient accelerates it not only sideways, but also in flow direction. Consequently, high curvature areas see high local flow speed. (I explained the physics in a very simple way; if you want to know more, please read &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;this&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qShXq.jpg&quot; alt=&quot;CFD plot of airfoil at moderate AoA&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Local speed at high angle of attack&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;With increasing angle of attack, the suction area over the airfoil needs to become stronger to force the airflow to follow the contour. Consequently, more of the oncoming flow is sucked over the wing, and the stagnation point shifts downwards on the airfoil's nose. Now the particles which hit the nose just above the stagnation point have to negotiate most of the nose's curvature, which needs more acceleration. This creates a suction peak in the flow around the nose and high local flow speed on the top side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flow over the bottom of the airfoil, however, will be decelerated near the stagnation point and see only little acceleration while it flows towards the trailing edge. See below for a plot of the inviscid pressure distribution. The pressure coefficient $c_p$ correlates with speed, and $c_p = 0$ means that local speed equals the flight speed of the airfoil. Negative values denote suction, and local speeds in excess of flight speed, whereas positive values of $c_p$ indicate slower speeds. Note that the y-axis is plotted reversed, with decreasing values up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f7wHm.png&quot; alt=&quot;Pressure distribution over chord of the NACA 2412 at several AOAs&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high local speed will also cause high local friction. Also, the long pressure rise on the upper side at high angle of attack needs more energy from the outer flow to keep flow attached, so the boundary layer grows here and slows down more of the air than at low angle of attack (again, extremely simplified). Both effects mean that drag goes up at higher angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you increase the angle of attack further, the flow is not able to follow the upper contour and will separate. This causes the pressure rise to stop at the separation point, so downstream the pressure decreases. Since this part of the airfoil points slightly backwards, this local suction increase will drive up drag. This starts before stall and on a well-behaved airfoil the separation point will first be near the trailing edge and move upstream with increasing angle of attack. This means then drag will rise progressively with higher angle of attack. Since most of the flow is still attached, lift will still grow until stall.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Optimum angle of attack&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The airfoil will be at its optimum angle of attack $\alpha$ with the best ratio of lift over drag $E_{opt}$ when the rate of lift increase with angle of attack equals the rate of drag increase times the optimum ratio of lift to drag. Once the local drag increase with angle of attack exceeds this value, the ratio of lift to drag decreases. Maybe this is easier to explain with a formula: $$E = \frac{L}{D}$$&#xA;To find the optimum we look at the point where the derivative of $E$ over $\alpha$ is 0:&#xA;$$\frac{\delta L}{\delta\alpha} = E_{opt} \cdot \frac{\delta D}{\delta\alpha}$$&#xA;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;rate of lift increase over angle of attack&lt;/a&gt; is quite constant until stall. At low angle of attack drag decreases with increasing $\alpha$ until the minimum drag point is reached. Then drag goes up slowly, so the ratio of lift to drag still grows. At one point both grow such that their ratio will not change much, and once the rate of drag increase grows even higher, the ratio will drop again. This all happens before stall.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-07T20:23:21.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11804" PostTypeId="2" ParentId="11786" CreationDate="2015-01-18T15:32:49.613" Score="7" Body="&lt;p&gt;My experience transitioning from airplanes to helicopters and then to gliders is that I never forget what I'm flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that sounds obvious, but its no different than the difference between driving a car with automatic transmission and manual, riding a motorcycle which has all the controls in a different place than a car and &lt;a href=&quot;http://en.wikipedia.org/wiki/Countersteering&quot; rel=&quot;nofollow&quot;&gt;countersteers&lt;/a&gt;, and flying an airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't reach for the throttle when I want to slow down in a car, and I don't turn the wheel in the direction of the turn when I'm riding a motorcycle. Similarly, when taking off in an airplane, I know I have to add power and pull back a bit to get it off the ground, and in a helicopter I inch the nose forward to gain &lt;a href=&quot;http://en.wikipedia.org/wiki/Translational_lift&quot; rel=&quot;nofollow&quot;&gt;ETL&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I don't act/react improperly when flying different aircraft is that it's all been trained into my muscle memory to do the right thing depending on the circumstances. I don't think of the horn in a helicopter as a stall horn, just like the buzzer in my alarm clock and smoke alarm are not stall horns. The horn in the heli is a low-rpm horn, and I ease the stick back not forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another complication is instrument flight. Although I am an instrument rated airplane pilot, I have a little hood time in a helicopter.  I'm so used to flying pitch and power against the AI that all my instincts under the hood in the heli were completely wrong. Nevertheless, I don't think I'll ultimately have any trouble flying instruments well in a heli.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-03-20T19:58:45.623" LastActivityDate="2015-03-20T19:58:45.623" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11806" PostTypeId="1" CreationDate="2015-01-18T19:30:03.000" Score="9" ViewCount="1408" Body="&lt;p&gt;&lt;em&gt;This question is based on &lt;a href=&quot;http://youtu.be/A513XCWTE3k&quot; rel=&quot;noreferrer&quot;&gt;this episode of Air Crash Investigation&lt;/a&gt; concerning &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;noreferrer&quot;&gt;crash of Lauda Air flight 004&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reverse Thrust Indicator warning is shown at 21 minutes and 10 seconds into the video. At the time of flight, such a warning was deemed a non-emergency, though wrongly. Yet should the pilots still have continued the flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think it safer to err on the side of caution, and try to land instantly whenever a warning emerges? The video depicts the pilots' verbalised guesses and thus perplexity over on the warning's causes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I anticipate two counterarguments: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Some warnings may be too minor to justify an immediate landing, but where is the line drawn? Anyways, this warning seems dire enough?&lt;/li&gt;&#xA;&lt;li&gt;Pilots may fear reprisals from their greedy employers for effectively cancelling the flight, for possibly a false negative, but a principled virtuous pilot would prioritise safety over monetary interests.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="128" LastEditorUserId="65" LastEditDate="2015-01-19T18:12:45.960" LastActivityDate="2015-01-20T04:48:50.823" Title="If a warning emerges, why not land as soon as possible?" Tags="&lt;emergency&gt;&lt;accidents&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11807" PostTypeId="1" CreationDate="2015-01-18T19:45:53.543" Score="4" ViewCount="368" Body="&lt;p&gt;&lt;em&gt;This question is based on &lt;a href=&quot;http://youtu.be/A513XCWTE3k&quot; rel=&quot;nofollow&quot;&gt;this episode of Air Crash Investigation&lt;/a&gt; concerning &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow&quot;&gt;crash of Lauda Air flight 004&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It discusses a test flight that simulates the crashed flight (41 minutes and 20 seconds into the video), in order to determine the effects of a sudden unintended reverse thrust deployment at higher altitudes and speeds, than those of the original test flight (which tested the deployment with the Boeing 767 at around 10,000 feet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, since there seemed no preventives or recourses for this test flight, was this test flight as dangerous and likely to crash as Lauda Air Flight 004? If so, was it a &lt;a href=&quot;http://en.wikipedia.org/wiki/Forlorn_hope&quot; rel=&quot;nofollow&quot;&gt;forlorn hope&lt;/a&gt; or suicide mission? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACI did mention that this test flight was conducted with the 4-engined DC-8, instead of the 2-engined B767, so is ACI implying that the greater number of engines on the DC-8 was a corrective?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="1696" LastEditDate="2015-01-20T03:28:48.277" LastActivityDate="2015-02-25T04:04:37.410" Title="Are there safety countermeasures for test flights that simulate crashed flights?" Tags="&lt;accidents&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11808" PostTypeId="1" AcceptedAnswerId="11809" CreationDate="2015-01-18T20:18:02.767" Score="18" ViewCount="7075" Body="&lt;p&gt;A lot of different aircraft have vertical or near-vertical fins below the empennage, or above the empennage and attached to the front of the vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What purpose do these devices serve?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7TyUm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/DWRDK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="1696" LastEditDate="2015-02-23T20:22:11.263" LastActivityDate="2015-05-18T12:05:09.403" Title="Why do some airplanes have vertical strakes?" Tags="&lt;aerodynamics&gt;&lt;seaplane&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11809" PostTypeId="2" ParentId="11808" CreationDate="2015-01-18T20:21:39.660" Score="6" Body="&lt;p&gt;Strakes serve to improve lateral stability in airplanes which may have certain features that make them less stable in yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, strakes are especially popular on floatplanes, and, indeed, the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook/media/faa-h-8083-23-2.pdf&quot; rel=&quot;nofollow&quot;&gt;Floatplane Flying Handbook&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On many airplanes, directional stability is affected to some extent&#xA;  by the installation of floats. This is caused by the length of the&#xA;  floats and the location of their vertical surface area in relation to&#xA;  the airplane’s CG. Because the floats present such a large vertical&#xA;  area ahead of the CG, they may tend to increase any yaw or sideslip.&#xA;  To help restore directional stability, an auxiliary fin is often added&#xA;  to the tail. Less aileron pressure is needed to hold the seaplane in a&#xA;  slip. Holding some rudder pressure may be required to maintain&#xA;  coordination in turns, since the cables and springs for the water&#xA;  rudders may tend to prevent the air rudder from streamlining in a&#xA;  turn.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There &lt;a href=&quot;http://www.aircraftstc.com/&quot; rel=&quot;nofollow&quot;&gt;are also STC kits&lt;/a&gt; that add strakes to different airplane, and whose manufacturers claim a variety of improved handling benefits, including &quot;Increased Yaw Stability.&quot;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-19T16:12:54.250" LastActivityDate="2015-01-19T16:12:54.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11810" PostTypeId="2" ParentId="11807" CreationDate="2015-01-18T21:10:57.430" Score="11" Body="&lt;p&gt;The test was flown on a DC-8-72. This model aircraft is certified to have its inboard thrust reversers deployed during flight, which means that the test was either within standard operational guidelines or not too far outside them (&lt;s&gt;it's possible it's not supposed to have reversers deployed at Mach 0.8, but it's allowed to have them deployed at speeds over 190 knots&lt;/s&gt; per @UnrecognizedFallingObject's comment, &lt;a href=&quot;http://www.avialogs.com/en/aircraft/usa/douglas/dc-8/dc-8-operations-manual-american-international-airways.html&quot; rel=&quot;nofollow&quot;&gt;thrust reversers are allowed up to Mmo&lt;/a&gt;). In addition, &lt;em&gt;both&lt;/em&gt; inboard thrust reversers were deployed; the TV show is wrong when they claim that there were 3 normal engines and one reversed one. As the test found, there was some buffeting, but there wasn't the need for too much lateral control input, because of the symmetry (there was a bit of asymmetry when &lt;em&gt;deploying&lt;/em&gt; reverse thrust, but not once both were deployed). Also, crucially, the flight crew was prepared for this, and they had the outboard engines fully spooled up (so while there was high sink rate at high speed, they had the power to come out of the dive safely). The test protocol had them maintaining airspeed, idling the reverse thrust engines before the end of the reverse thrust run, and then having engines at full thrust already to pull up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, the reason it wasn't a suicide flight was that the flight crew was prepared, the plane could take some degree of reverse thrust in flight, the reverse thrust was symmetric, the outboard engines were both spooled up and pitch was adjusted to maintain airspeed, and in general it was a controlled test environment. The TV show implies it was to see if it was possible to recover. That was not the purpose of the test; they set up the test so they &lt;em&gt;knew&lt;/em&gt; they could recover, and the purpose was to see the effect on airflow over the wing in as controlled an environment as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://lessonslearned.faa.gov/Lauda/Nasa_memo_110351.pdf&quot; rel=&quot;nofollow&quot;&gt;NASA report on the test flight&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="923" LastEditDate="2015-02-25T04:04:37.410" LastActivityDate="2015-02-25T04:04:37.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11811" PostTypeId="2" ParentId="11746" CreationDate="2015-01-18T21:46:46.477" Score="8" Body="&lt;p&gt;Ask if the traffic is ahead or crossing. If it's ahead, you can negotiate to remain at the current level by slowing down to 'his' speed/Mach no. If this is not an option, then I'd ask if I'd ask for a radar vector to avoid the traffic (possibly even a direct to YXZ) for separation - the controller will be able to see on her/his radar screen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If still no joy, then you have no choice but to descend. Once down at the new level, ask when can you expect further climb - that way you can plan on whether you need to recompute your fuel or merely cruise for the next 20 mins (or whatever the case may be).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, worst case scenario - lets say that you are stuck at your lower FL or altitude for the remainder of your trip knowing that you will not be allowed to climb, then your options are to request direct to ABC (short cut) and possibly make up some fuel at expense of arriving later due to your lower TAS/Mach no. or, get out the performance manual and calculate at that particular level/FL, what is your best endurance fuel flow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking it further....now lets say you have exhausted all possibilities and ATC is still not accommodating you - now you can get an update of your destination's weather and assess whether at your revised ETA if the weather is still AT OR ABOVE landing minimums FOR THE APPROACH IN USE AT THE TIME OF ARRIVAL. If the weather is landing minimum or better, then you can legally continue to your destination using your alternate fuel as extra fuel. &#xA;The legality is to land with reserves, not alternate plus reserves. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You declare minimum fuel to ATC if at any stage of the flight, you anticipate that any other changes to the present flight route/conditions will cause you to land with less than reserve fuel.&lt;/strong&gt; (note: this implies you now still have enough fuel to land with reserves intact. If you don't, then it is not minimum fuel you declare, but a fuel emergency) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if the weather at your destination is CAVOK and you filed IFR, since you are carrying an alternate, you are legal to use your alternate fuel after checking the weather (as previously mentioned). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your destination weather is marginal....lets say it's RIGHT AT MINIMUMS you might find the weather whilst you are on the instrument approach reduces to below landing minimum as you pass the final approach fix...lets say you descend to 100 feet above the runway and cannot identify threshold markings, runway lights, edge lights - the landing environment [first 3000 feet (914 metres) of the runway], then you must perform the missed approach and assess whether you have enough fuel for another approach or merely fly to your alternate. This is an example whereby you would do what you can to preserve your alternate fuel as you may actually use it in the latter part of your flight. &lt;/p&gt;&#xA;" OwnerUserId="6905" LastEditorUserId="755" LastEditDate="2015-08-17T05:30:39.263" LastActivityDate="2015-08-17T05:30:39.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11812" PostTypeId="2" ParentId="11808" CreationDate="2015-01-18T22:40:04.323" Score="30" Body="&lt;p&gt;The vertical tail surface is like a wing, maybe with a smaller aspect ratio, but it works much the same over sideslip as a wing works over angle of attack. The fuselage, however, is a slender body with a much smaller lift curve slope, but a much higher &quot;stall&quot; angle. In fact, its lift curve slope is nonlinear and tends to increase with higher angles of attack and angles of sideslip. If you want to know more how the lift curve slope varies with aspect ratio, &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;please read this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that at some sideslip (around 15° for most configurations) the vertical tail stalls and its stabilizing side force decreases with further increase in the sideslip angle, whereas the destabilizing influence of the fuselage increases further. The aircraft becomes laterally unstable pretty soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To buy a little more stability around the point where the vertical tail stalls, these strakes have been added. They have a high leading edge sweep, so they will produce &lt;a href=&quot;http://en.wikipedia.org/wiki/Vortex_lift&quot; rel=&quot;noreferrer&quot;&gt;vortex lift&lt;/a&gt; just like a highly swept delta wing, only sideways. The suction force of this vortex will act on the root of the vertical, just were it has the biggest chord. In fact, this helps to keep most of the vertical active, because now it becomes part of that delta wing ahead of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The strakes in the upper picture have a different purpose on top, however. They limit &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; on the rear fuselage in high speed flight by preventing crossflow. Actually, they are an embarrassment for the aerodynamicist, because they show that the lower fuselage suffers from flow separation just when it hurts most.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most military cargo aircraft have them, because in order to keep the ramp short and to provide enough clearance for rotation, their tailcones are steeper than what the airflow can manage. Among modern military transporters, only the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot; rel=&quot;noreferrer&quot;&gt;Lockheed C-5&lt;/a&gt; (thanks to @dotancohen for the hint!) and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-70&quot; rel=&quot;noreferrer&quot;&gt;Antonov-70&lt;/a&gt; can do without them. This was a definite source of pride for the chief aerodynamicist of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov&quot; rel=&quot;noreferrer&quot;&gt;Antonov Design Bureau&lt;/a&gt;, Oleg Bogdanov.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower fin in the second picture was added to compensate the destabilizing influence of the two floats, which will destabilize the aircraft in much the same way as the fuselage does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extending the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5239/would-a-vertical-stabilizer-that-extends-both-above-and-below-the-centerline-be/5242#5242&quot;&gt;vertical downwards also helps to improve handling qualities&lt;/a&gt; and should be done as much as tail strike clearance allows.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-18T12:05:09.403" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11813" PostTypeId="2" ParentId="11806" CreationDate="2015-01-19T00:01:30.813" Score="4" Body="&lt;p&gt;It depends on the emergency. Some of them are bad enough that landing immediately is required by the manual, and some can be deferred until you reach the closest airport, and some can be deferred until you reach your destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example from the R-22 Aircraft Flight Manual regarding the &lt;strong&gt;clutch&lt;/strong&gt; light. The manual provides a process whereby the clutch can be disabled to prevent it from loosening anymore (a very hazardous situation), and then says &quot;land as soon as practical,&quot; but if there are compounding factors, then find a field or other open space and land right away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bE3Ka.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6fAss.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In large aircraft, there is a &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Annunciator_panel&quot; rel=&quot;nofollow noreferrer&quot;&gt;centralize warning panel&lt;/a&gt;&lt;/em&gt; which look something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MeJ17.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The color of each annunciator light means something different:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Red: Warning, this systems condition is critical and requires    immediate attention (such as an engine fire, hydraulic pump failure)&lt;/li&gt;&#xA;  &lt;li&gt;Amber: Caution, this system requires timely attention or may do so in    the future (ice detected, fuel imbalance) &lt;/li&gt;&#xA;  &lt;li&gt;Green: Advisory/Indication,    a system is in use or ready for operation (such as landing gear down    and locked, APU operating) &lt;/li&gt;&#xA;  &lt;li&gt;White/blue: Advisory/Indication, a system    is in use (seatbelt signs on, anti-ice system in-use, landing lights    on)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And all the yellow &lt;em&gt;caution&lt;/em&gt; and all the red &lt;em&gt;warning&lt;/em&gt; lights are re-annuciated directly in front of the pilot's eyes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/elXGw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on color of the light, the pilot can tell the severity of the problem, although as you point out, sometimes he can make a mistake.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-19T00:21:41.037" LastActivityDate="2015-01-19T00:21:41.037" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11814" PostTypeId="1" AcceptedAnswerId="11817" CreationDate="2015-01-19T05:19:23.800" Score="14" ViewCount="41463" Body="&lt;p&gt;Many flight tracking websites have the data about almost all the commercial airplanes in air. Do they have the data about the private jets and/or defense aircraft also and they just don't show that on the websites?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="65" LastEditDate="2015-01-19T15:33:05.697" LastActivityDate="2021-01-21T05:37:57.457" Title="Do flight tracking websites also track non-commercial and defense aircraft?" Tags="&lt;flight-stat&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11815" PostTypeId="2" ParentId="11814" CreationDate="2015-01-19T05:32:33.647" Score="5" Body="&lt;p&gt;Flight tracking websites, such as &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;nofollow&quot;&gt;FlightRadar24&lt;/a&gt; and &lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;FlightAware&lt;/a&gt;, generally track aircraft using publicly available &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_dependent_surveillance-broadcast&quot; rel=&quot;nofollow&quot;&gt;ADS-B transponder&lt;/a&gt; information. Privately operated aircraft are included as long as the owner of the aircraft has not specifically requested that their aircraft be excluded from public searching. For example: Steve Jobs' private plane's N-number was public information, but it was excluded from tracking on Flightaware. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aircraft are not included in public ADS-B tracking information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more on ADS-B and flight tracking, see the information from &lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot; rel=&quot;nofollow&quot;&gt;FlightRadar24&lt;/a&gt; and &lt;a href=&quot;http://flightaware.com/about/faq&quot; rel=&quot;nofollow&quot;&gt;FlightAware&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6907" LastEditorUserId="1696" LastEditDate="2015-01-19T16:00:25.317" LastActivityDate="2015-01-19T16:00:25.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11816" PostTypeId="2" ParentId="11814" CreationDate="2015-01-19T07:03:12.977" Score="6" Body="&lt;p&gt;From the &lt;a href=&quot;http://flightaware.com/about/faq#intl&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightAware FAQ&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;How does FlightAware handle flights around the world? What is FlightAware's service area?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;FlightAware's primary service area includes airspace operated by the United States (including Alaska, Hawaii, Puerto RIco, and Guam), Canada, the Caribbean, Australia, the United Kingdom, and France. Flights in the primary service area support real time maps, departure and arrival information, delays, and more.&lt;/p&gt;&#xA;&lt;p&gt;FlightAware's secondary service covers scheduled major airline operations at any airport in the world. Flights in the secondary service area support departure and arrival information. Secondary coverage areas may have real-time positions for ADS-B equipped aircraft operating in FlightAware's ADS-B coverage area. Additionally, some airlines send FlightAware satellite position reports from aircraft worldwide that augments other position data and provides transoceanic coverage as well.&lt;/p&gt;&#xA;&lt;p&gt;For flights arriving in a service area from outside of a service area, FlightAware will be able to track the flight when it nears a service area. For flights departing a service area, FlightAware will be able to track the flight until it leaves the coverage area. Flights may not be tracked beyond that point unless they enter another service area.&lt;/p&gt;&#xA;&lt;p&gt;Not all worldwide data sources (e.g., European data, datalink ARINC/SITA ACARS, etc) are freely available on FlightAware.com due to government regulations or commercial arrangements. You can contact us if you have a commercial need for worldwide data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6908" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-19T18:13:59.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11817" PostTypeId="2" ParentId="11814" CreationDate="2015-01-19T07:05:42.273" Score="14" Body="&lt;p&gt;As long as an aircraft transmits (unencrypted) ADS-B information, anyone within radio range can track it. The equipment necessary to receive ADS-B can be as simple as a computer with a TV receiver (USB DVB-T module) and the right software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Receivers can then send the data stream to, for example, &lt;a href=&quot;http://flightradar24.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flightradar24&lt;/a&gt;, who will display it on their website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Flightradar24 states, not all aircraft are equipped with an ADS-B transponder, and even those that do may not have switched it on. Unless ADS-B is installed and operating, it would not be visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@ezra-g mentiones that Steve Jobs' aircraft was &lt;a href=&quot;http://www.fly.faa.gov/ASDI/asdi.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;blocked&lt;/a&gt;, but this is of something one would have to ask for, and the site has to apply the filter so it doesn't display on its website. However, Jobs' plane would still have been visible on the receiving computers. And, of course, the website will only filter your aircraft if they are willing to do so, either on request, through payment, or a government order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://Flightradar.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flightradar.com&lt;/a&gt; also has some other data sources, like FAA (Federal Aviation Administration) radar information in the US, which also contains aircraft without a transponder. The FAA may also filter some aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="18400" LastEditDate="2018-03-19T23:29:53.190" LastActivityDate="2018-03-19T23:29:53.190" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11818" PostTypeId="1" AcceptedAnswerId="18895" CreationDate="2015-01-19T16:49:20.587" Score="12" ViewCount="40790" Body="&lt;p&gt;I am a student pilot and I usually round out too high and I am not sure why. Can somebody  guide me how to make decision whether I am too high or not.&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="65" LastEditDate="2015-01-19T17:07:41.640" LastActivityDate="2017-04-08T06:30:45.287" Title="What is the best method to time your round out or flare in Cessna 172?" Tags="&lt;landing&gt;&lt;cessna-172&gt;" AnswerCount="12" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11819" PostTypeId="2" ParentId="3157" CreationDate="2015-01-19T17:00:43.700" Score="0" Body="&lt;p&gt;Even if one started a search with many vessels whose equipment can detect nothing more than that a beacon exists somewhere within 16km, a ship that detected a beacon's signal could summon one or more ships with fancier equipment which would be able to home in on the signal much more accurately.  I don't think that encoding a plane's last above-ground location in the ping data would assist significantly with locating the beacon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the black box &quot;blindly&quot; encode any significant amount of information in its pings would add greatly to the power requirements; there might be some benefit to having a black listen occasionally (the pings would indicate when) for an outside request for data, and then transmit some of its data in response to such requests.  This could be helpful in cases where the box could be located, but was in a place that salvage equipment could not reach.  Only a limited amount of data could be transmitted, however; depending upon how far away it needed to be received, transmitting even a minute's worth of audio might use more energy than a month's worth of pings.  I don't know that the number of cases where a box is detected, and holds data, but cannot be physically retrieved, would be sufficient to justify the extra cost and complexity of ultrasonic data communication.  It would probably cheaper to add redundant recorders to the aircraft in places that would likely end up in different parts of the debris field, so as to maximize the likelihood that at least one would be reachable by salvage craft.&lt;/p&gt;&#xA;" OwnerUserId="973" LastActivityDate="2015-01-19T17:00:43.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11821" PostTypeId="2" ParentId="11806" CreationDate="2015-01-19T17:09:02.640" Score="7" Body="&lt;p&gt;As rbp explained, information provided to the pilots is differentiated based on how serious the problem is, from informational up to emergency. Part of designing an aircraft is determining how serious different failures will be.&lt;/p&gt;&#xA;&lt;p&gt;As technology has advanced, aircraft have become more and more complex. New devices and systems allow aircraft to become faster, safer, more capable, and more comfortable. However, more complexity means more things that can fail. The airplane's systems are analyzed to understand the ways that a system may fail, and how it will affect the rest of the airplane. The results are used to determine how serious different indications may be, and to provide instructions to the crew about what procedures to follow.&lt;/p&gt;&#xA;&lt;p&gt;With the complexity of modern aircraft, it is much more likely for at least one system to have an issue. It does not make sense to ground an aircraft just because a coffee maker isn't working. Aircraft will have a minimum equipment list (&lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=4590&quot; rel=&quot;noreferrer&quot;&gt;MEL&lt;/a&gt;) which allows the aircraft to depart with certain systems inoperative. Circumstances such as &lt;a href=&quot;http://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;noreferrer&quot;&gt;ETOPS&lt;/a&gt; will further limit which systems may be inoperative. Once in the air, the crew is informed by their checklists about the correct actions to take. Some indications are not critical, others will be. Modern aircraft go even further in determining the severity of indications. Certain less critical information will be suppressed during high-workload phases like takeoff and landing to avoid distracting the crew. Some aircraft will even make it simple for the crew and give them a message like &amp;quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/6385/difference-between-land-asap-and-land-ansa&quot;&gt;LAND ASAP&lt;/a&gt;&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;The basic FAA regulation for crew alerting systems on transport aircraft such as the 767 in your example is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.25_11322&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §25.1322 (b)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(1) Warning: For conditions that require immediate flightcrew awareness and immediate flightcrew response.&lt;/p&gt;&#xA;&lt;p&gt;(2) Caution: For conditions that require immediate flightcrew awareness and subsequent flightcrew response.&lt;/p&gt;&#xA;&lt;p&gt;(3) Advisory: For conditions that require flightcrew awareness and may require subsequent flightcrew response.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is up to the group certifying the aircraft to convince the FAA whether something requires immediate awareness and/or immediate response.&lt;/p&gt;&#xA;&lt;p&gt;Some specific alert systems are covered in different sections, such as &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.25_11305&quot; rel=&quot;noreferrer&quot;&gt;§25.1305 (d)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) A position indicating means to indicate to the flightcrew when the thrust reversing device—&lt;/p&gt;&#xA;&lt;p&gt;(i) Is not in the selected position, and&lt;/p&gt;&#xA;&lt;p&gt;(ii) Is in the reverse thrust position, for each engine using a thrust reversing device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There isn't much more specific than that, but there are other rules that affect the warning system such as &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.25_1729&quot; rel=&quot;noreferrer&quot;&gt;§25.729 (e)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(6) Failures of systems used to inhibit the landing gear aural warning, that would prevent the warning system from operating, must be improbable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So in order to make a failure of the warning improbable, the system may display a false indication rather than fail to indicate a valid problem. Most indications for things such as fires are false. It is much better for the system to assume the worst if in doubt, and for the crew to assume the indication is valid and act accordingly.&lt;/p&gt;&#xA;&lt;p&gt;So, to answer your questions:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The systems are analyzed to determine which indications are&#xA;important enough to alert the crew, and what the crew's response should be. These decisions will be reviewed&#xA;at certification to convince the FAA (or local authority) that these&#xA;decisions are sound.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As always, the ultimate responsibility of the aircraft lies with the&#xA;captain. If the captain feels that diverting is the safest option,&#xA;he or she can make that decision. An operator with a good culture of safety will never cause a captain to&#xA;fear reprisal for making such an informed decision in the interest&#xA;of safety.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-19T17:09:02.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11822" PostTypeId="2" ParentId="11818" CreationDate="2015-01-19T17:11:39.510" Score="1" Body="&lt;p&gt;I don't think of round-out as at an altitude, I think of it as at a horizontal position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm established on the PAPI/VASI vertical guidance, then when the numbers are directly below me, and the Touchdown Bars are filling my windscreen, then its time to flare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;If you're flaring too high, its because you're flaring too soon.&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;(You can probably still see the numbers.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Obviously, adjust your flight ONLY WITH AN INSTRUCTOR)&lt;/em&gt;&lt;br&gt;Try not judging altitude, but judging position and sight-picture.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-01-19T17:21:51.717" LastActivityDate="2015-01-19T17:21:51.717" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11823" PostTypeId="2" ParentId="11818" CreationDate="2015-01-19T17:27:49.753" Score="4" Body="&lt;p&gt;Many students flare too high - instinct is to not fly into the ground. Don't get discouraged, it will come with practice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me it's not a time thing or a sight thing, but a feel thing. I found flying at night to be a great thing for my landings because you have to depend more on feel than you do visual cues. If you get used to a certain sight picture and you then go to a different airfield you can get thrown off by a wider or narrower runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try closing your eyes and following through on the controls while your instructor lands, pay attention to the seat of the pants feel. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-01-19T17:27:49.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11824" PostTypeId="2" ParentId="11818" CreationDate="2015-01-19T17:28:42.317" Score="13" Body="&lt;p&gt;The usual cause for flaring too high is that the pilot is looking at the runway in front of the propeller instead of down at the far end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next time you're up with your instructor, have him do the landing, and look at the far end of the runway while using your peripheral vision to judge your height above the surface. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the next lap, you fly the airplane, and try to get the same sight picture, both in front of you, and in your peripheral vision.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-19T17:28:42.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11825" PostTypeId="1" AcceptedAnswerId="11826" CreationDate="2015-01-19T17:44:35.953" Score="10" ViewCount="1126" Body="&lt;p&gt;On my 2014-01-18 CET flight ST2114 from FKB to LPA on a &lt;a href=&quot;http://en.wikipedia.org/wiki/Germania_(airline)&quot; rel=&quot;noreferrer&quot;&gt;Germania airplane&lt;/a&gt;, cabin lights were switched from white to blue for takeoff. I recorded this in a &lt;a href=&quot;https://theta360.com/s/bwA4qcgjMW8Y7vtfQh2uEyuA4&quot; rel=&quot;noreferrer&quot;&gt;panoramic photo&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted, on sunset, the sun coming in through the windows made up for a beautiful play of light: Blue and yellow are complementary colors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Is there a security or technical reason for the blue light, or is it just for&#xA;aesthetics?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="6913" LastEditorUserId="167" LastEditDate="2015-01-20T03:25:02.730" LastActivityDate="2015-01-20T03:25:02.730" Title="Is there a reason Germania aircraft cabins have blue lights?" Tags="&lt;cabin-design&gt;&lt;aircraft-lighting&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11826" PostTypeId="2" ParentId="11825" CreationDate="2015-01-19T18:04:10.700" Score="12" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/University_of_Wuppertal&quot;&gt;Bergische Universität Wuppertal&lt;/a&gt; has done some research that chronobiologically-adapted LED lighting can enhance passengers well being and they can sleep better during a flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ledsmagazine.com/articles/2013/01/chronobiologically-adapted-led-lighting-improves-aircraft-cabin-environment.html&quot;&gt;This article&lt;/a&gt; details about this research:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Adaptive solid-state lighting (SSL) scenarios in which the color and&#xA;  brightness of lighting is varied during long-distance overnight&#xA;  flights results in passengers that sleep better and are more alert&#xA;  upon arrival.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... at the start of an overnight flight that warm-white light helps to&#xA;  stimulate melatonin production and increases passenger relaxation ...&#xA;  blue-rich cold light in the morning increased alertness&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There have been studies showing benefits of &lt;a href=&quot;http://www.osram.com/osram_com/press/press-releases/_general_interest_press/2012/airbus/index.jsp&quot;&gt;biologically effective lighting for more relaxed flights&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-01-19T18:04:10.700" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11827" PostTypeId="1" AcceptedAnswerId="11834" CreationDate="2015-01-19T18:11:09.047" Score="36" ViewCount="12175" Body="&lt;p&gt;Examples: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A bank angle &gt; 45 degrees is considered an “upset,” putting the plane in a position that can lead to a loss of control.&lt;/li&gt;&#xA;&lt;li&gt;A pitch &gt; 20 degrees can possibly be dangerous and cause the aircraft to stall (depends on many factors or course).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are just a few examples of limits that most passenger jets have. Now why is it that the plane actually accepts input that will cause the aircraft to go beyond these limits? What possibly use could “diving” straight towards the ground or towards the sky have? Or having a high bank angle that will almost certainly cause stalling and loss of control?&lt;/p&gt;&#xA;" OwnerUserId="4270" LastEditorUserId="4067" LastEditDate="2015-01-21T10:53:22.547" LastActivityDate="2018-06-19T13:58:04.070" Title="Why do passenger jets accept input that will cause the aircraft to perform dangerous maneuvers it was not designed for?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;passenger&gt;&lt;jet&gt;&lt;fly-by-wire&gt;" AnswerCount="14" CommentCount="14" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11828" PostTypeId="2" ParentId="11827" CreationDate="2015-01-19T18:21:57.210" Score="22" Body="&lt;p&gt;The philosophy is that the pilot knows best. If they need to make a maneuver, they should be trusted to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although there are absolute limits such as structure, other limits are less exact and depend on conditions (and even structure is built to withstand additional margins, failure, and damage). Something that qualifies as an &quot;upset&quot; is certainly not routine, but it is not necessarily fatal either, and can be used to deal with certain situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A big reason for abrupt maneuvers would be avoiding an obstacle. In the case of terrain, this would generally be a steep climb, or possibly a steep turn. But this could also be another aircraft, in which case the pilot may want to descend quickly.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-01-19T18:21:57.210" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11829" PostTypeId="2" ParentId="11806" CreationDate="2015-01-19T19:23:07.317" Score="5" Body="&lt;p&gt;That are problems where landing as soon as possible is appropriate and problems where it would be a &lt;strong&gt;bad idea&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many systems on a modern aircraft are used in take-off and landing and don't affect cruise flight much. When such system fails, it usually causes no trouble at the moment, but pilots know that it will complicate landing. In such case it's better to remain in the air, possibly continue to destination, and land when the aircraft has burnt most of it's fuel and is light. And possibly divert to an airport with longer runway, better weather, easier approach procedure or better maintenance facilities depending on what is needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And note that thrust reversers are just such system. Most reverser faults just mean you won't be able to use them on landing and thus need to factor in a larger margin of error. And that is easier when the plane is light, so continuing to destination makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How it works regarding distinction between warning and caution is already explained in the other answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that in case of Lauda Air flight 004 if they did decide to divert it would not have helped them because landing from cruise flight level takes 20-30 minutes even if there is suitable airport nearby. They would have had to shut the engine down and there was nothing indicating they should. The message was apparently amber indicating a fault, but if it didn't sound master warning they didn't have any reason to think they should.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-19T19:23:07.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11830" PostTypeId="2" ParentId="11827" CreationDate="2015-01-19T20:35:31.970" Score="15" Body="&lt;p&gt;Most new designs do &lt;strong&gt;not&lt;/strong&gt; accept such inputs. That includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airbus models from A320 onwards (includes A318 and A319 that are variants of A320).&lt;/li&gt;&#xA;&lt;li&gt;Boeing models B777 and B787.&lt;/li&gt;&#xA;&lt;li&gt;Sukhoi SuperJet Su100.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Airbus has roll limit 65°, not 45°, but it automatically returns to at most 33° without constant pressure on the stick. I can't find explicit pitch limit, but it has alpha-limit (angle-of-attack, depends on type, 17° for A320, pitches down not to exceed it), maximum speed and Mach limit (pitches up if exceeded) and minimum and maximum wing loading (vertical acceleration, -1G to +2.5G clean, 0G to +2G with flaps)&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-19T20:35:31.970" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11831" PostTypeId="2" ParentId="11827" CreationDate="2015-01-19T20:42:04.803" Score="18" Body="&lt;p&gt;Let's just focus on roll. The same command that can be used to roll the aircraft form 0° roll angle to 30° can be used to roll it from 30° to 60°. Who is to decide at what roll angle the airplane is and that from now on no further roll commands are acceptable?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A computer-controlled &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;FCS&lt;/a&gt;, obviously, if we decide the pilots cannot be trusted. But can we trust the FCS more? What would be the basis for it to establish the correct roll angle?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Gyros? They need to be calibrated once in a while, because all gyros drift. Some more, some less, but no technology can prevent them from showing dangerously wrong readings when they are left running long enough.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Accelerometers which show the gravity vector? As soon as the airplane flies a &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;coordinated turn&lt;/a&gt;, it should be obvious that they point only away from the lift vector. No dice. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Radar altimeter at the wingtips? Fly high enough and they become useless. This might work for low-level flight, but not in all flight phases.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Camera and image processing to find the attitude towards the horizon? Stops working at night or in fog.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I could extend the list, but by now it should become clear that this is not as easy as it sounds. Especially the FCS design for autonomous &lt;a href=&quot;http://en.wikipedia.org/wiki/Unmanned_aerial_vehicle&quot; rel=&quot;nofollow noreferrer&quot;&gt;UAV&lt;/a&gt;s is quite tricky and needs to correlate the inputs of different sensors in order to establish level flight. This was learned the hard way by &lt;a href=&quot;http://www.aurora.aero/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aurora Flight Sciences&lt;/a&gt; when flight-testing their Perseus A prototype. Relying on the gyro alone, the team did not realize that the sensor drifted away and commanded increasingly steep bank angles. When the aircraft disintegrated, the team did not even immediately realize what had happened because the maximum sink rate value on the flight data downlink corresponded to just 20 m/s - it just got stuck at -1023 counts. &lt;a href=&quot;https://books.google.de/books?isbn=0160915414&quot; rel=&quot;nofollow noreferrer&quot;&gt;The aircraft prototype was totally destroyed in the accident&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SrgUM.jpg&quot; alt=&quot;Perseus A before its final 21st flight&quot;&gt; Perseus A before its final 21st flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess this is the last forum on the whole Internet where it needs to be explained that relying on perfectly functioning software is foolish. Somehow, human pilots are still better at resolving unforeseen difficulties, for the same reasons why they sometimes screw up in inexplainable ways.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T20:24:28.480" LastActivityDate="2015-05-07T20:24:28.480" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11832" PostTypeId="1" AcceptedAnswerId="11833" CreationDate="2015-01-19T22:30:11.377" Score="6" ViewCount="1558" Body="&lt;p&gt;If one wants to circumnavigate the planet in a general aviation airplane, how can one do it and what are the important issues to consider?&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-12T15:06:30.523" Title="What the preparations and procedures to consider for circumnavigation?" Tags="&lt;flight-planning&gt;&lt;navigation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11833" PostTypeId="2" ParentId="11832" CreationDate="2015-01-19T22:30:11.377" Score="9" Body="&lt;p&gt;Circumnavigating the planet Earth very popular &lt;em&gt;hobby&lt;/em&gt; and a courageous endeavor. It is not an easy task and requires extensive preparation, planning and training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is circumnavigation?&lt;/strong&gt;&lt;br&gt;&#xA;Travelling around an island, a continent, or the entire world is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Circumnavigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;circumnavigation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is considered global circumnavigation?&lt;/strong&gt;&lt;br&gt;&#xA;Crossing all &lt;a href=&quot;http://en.wikipedia.org/wiki/Meridian_(geography)&quot; rel=&quot;nofollow noreferrer&quot;&gt;meridians&lt;/a&gt; is not considered global circumnavigation. If you  walk completely around either Pole, you have crossed all meridians, but this is not generally considered a &lt;em&gt;circumnavigation&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A basic definition is a route which covers at least one &lt;a href=&quot;http://en.wikipedia.org/wiki/Great_circle&quot; rel=&quot;nofollow noreferrer&quot;&gt;great circle&lt;/a&gt;, and it passes through at least one pair of points of &lt;a href=&quot;http://en.wikipedia.org/wiki/Antipodes&quot; rel=&quot;nofollow noreferrer&quot;&gt;antipodal&lt;/a&gt; to each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What are requirements for circumnavigation by airplane?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The route should start and finish at the same point.&lt;/li&gt;&#xA;&lt;li&gt;It should cross all meridians.&lt;/li&gt;&#xA;&lt;li&gt;The course must be at least 22,858.729 miles (36,787.559 kilometers) long. This is length of &lt;a href=&quot;http://en.wikipedia.org/wiki/Tropic_of_Cancer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tropic of Cancer&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;It must include set control points at latitudes outside the &lt;a href=&quot;http://en.wikipedia.org/wiki/Arctic_Circle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Arctic&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Antarctic_Circle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antarctic&lt;/a&gt; circles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MqICG.jpg&quot; alt=&quot;Earth&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do people do it?&lt;/strong&gt;&lt;br&gt;&#xA;Yes, a lot of people do it. &lt;a href=&quot;http://www.earthrounders.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Earth Rounders&lt;/a&gt; shares experiences of pilots who have flown around the world. It is categorized by engine types and solos etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What should I need to know?&lt;/strong&gt;&lt;br&gt;&#xA;A lot. Typically, people who flew around the world typically break their journey in 80-100 flights, or even more. It takes several months. Each flight of circumnavigation is significantly longer than a typical cross-country flight. It is much harder on many levels than an ordinary cross-country flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.soloflights.org/comment_e.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;This website&lt;/a&gt; takes about the preparations thoroughly. It covers these section:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Pilot&lt;/li&gt;&#xA;&lt;li&gt;The Aircraft&lt;/li&gt;&#xA;&lt;li&gt;Preparation&lt;/li&gt;&#xA;&lt;li&gt;Survival equipment&lt;/li&gt;&#xA;&lt;li&gt;The flight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Because of the longevity of this article, I am not duplicating it here as it contains all very useful information.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What are other people's experience?&lt;/strong&gt;&lt;br&gt;&#xA;There are many people who have thoroughly documented their journeys, the preparations, the hazards and difficulties they faced, and many pictures and videos. I am listing a few, which certainly are not the best ones, but give a decent idea about their trip.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.australianflying.com.au/news/cessna-pilot-completes-10-year-double-circumnavigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Robert Gannon&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.earthrounders.com/cgi/archive/garratt/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carol Ann Garratt&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://kesaniemi.kapsi.fi/fs2004/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Simulator X&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Although this is in a simulation, but this trip is very thoroughly planned and it contains detailed path descriptions.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-02-12T15:06:30.523" LastActivityDate="2015-02-12T15:06:30.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11834" PostTypeId="2" ParentId="11827" CreationDate="2015-01-19T22:30:14.343" Score="53" Body="&lt;p&gt;Generally speaking, pilots don't like it when a computer interprets or limits their actions. They want final control. They don't always get their way on this but that's their preference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I recall correctly, Boeing tends to stick with the philosophy that &quot;the pilot is the final arbiter.&quot; Airbus is more likely to preempt pilot inputs and modify them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the majority of crashes and incidents wind up being pilot error, there is a serious flaw to modifying pilot inputs. That flaw is in the case of systems failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By definition, failure modes involve things going wrong.  When things go wrong it's effectively impossible to plan, in automation, for all contingencies. People are much better at responding to the unknown than automation systems are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take for instance the rule that &quot;bank angles &gt; 45 degrees are dangerous, and are therefore prohibited&quot;. How does the plane know that the bank angle is &gt; 45 degrees? Well it's a sensor of course, but what if the sensor has failed? A failed sensor will either signal to take action when none is needed or fail to signal when action is called for. What if the control surfaces have failed and the plane cannot correct the bank angle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual answer to that is redundant systems, high reliability parts and design, etc.  All those are great of course and certainly help a lot. However we still have incidents and accidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end the question is: Who do you trust more? A pilot or a machine? And statistics and science only help you part-way here. A person's experience, biases and feelings will have a lot to say about how they answer. And by &quot;person&quot;, understand that I'm including the customers, the paying public.&lt;/p&gt;&#xA;" OwnerUserId="6916" LastEditorUserId="-1" LastEditDate="2015-01-21T17:14:15.240" LastActivityDate="2015-01-21T17:14:15.240" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="11835" PostTypeId="2" ParentId="9243" CreationDate="2015-01-20T00:22:41.223" Score="0" Body="&lt;p&gt;Cost. That's it. Human life does have a cost associated with it. Its ugly to think about, but of course we have the technology to do something like this.&#xA;Extra parachute systems would weigh more- and that dead weight has a cost in gallons of jet A, maintenance, life cycle and all the other things that go on the other side of the balance sheet. The aviation manufacturers build the planes their customers want- and their customers don't want to pay for the additional product maintenance life cycle cost of an extra couple tons of safety equipment.&lt;/p&gt;&#xA;" OwnerUserId="6917" LastActivityDate="2015-01-20T00:22:41.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11836" PostTypeId="2" ParentId="9243" CreationDate="2015-01-20T04:26:20.830" Score="-3" Body="&lt;p&gt;The bottom line for most operators is that modern airplanes simply don't crash.  In the West, the probability is just about zero, so no emergency devices like this are needed.&lt;/p&gt;&#xA;" OwnerUserId="6920" LastEditorUserId="167" LastEditDate="2015-01-20T04:45:57.050" LastActivityDate="2015-01-20T04:45:57.050" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11837" PostTypeId="2" ParentId="11806" CreationDate="2015-01-20T04:48:50.823" Score="2" Body="&lt;p&gt;The B767 in Lauda Airlines example had been showing reverser warnings for a long time and the systems were investigated so many times, yet no fault was found.  Therefore the warning wasn't seen as &quot;dire enough&quot;. No simulations of deployment during cruise flight were included in pilot training; therefore the crews tended to dismiss the warnings. Accidental deployment at cruise was found to be survivable IF the pilots recognized the deployment and reacted in LESS THAN 1 second.  Without additional training, the pilots took too long to recognize the deployment and the plane would be doomed.&lt;/p&gt;&#xA;" OwnerUserId="6920" LastActivityDate="2015-01-20T04:48:50.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11838" PostTypeId="2" ParentId="11521" CreationDate="2015-01-20T05:12:53.393" Score="5" Body="&lt;p&gt;The MPL doesn't allow the holder to fly as Pilot-in-Command, although in a pinch he probably could do it.  It's a basic ticket to allow a non-ATPL pilot to fly as a fully qualified crew-member of an aircraft that otherwise requires the full ATPL ticket.  Elsewhere the pilot would likely be accumulating only solo experience, and he won't be much use when transitioning to a multi-crew airplane.  The MPL only allows the holder to act as copilot, 2nd officer (flight engineer) or cruise pilot, not as PIC, on any flight including to the USA. Where it's used, the MPL holder will be granted his ATPL when he completes any additional regulatory requirements and has accumulated the required hours. The MPL pilot is entitled to fly in his aircraft as co-pilot from anywhere outside the USA into the USA, although not in a USA-registered aircraft. Some pilots start their MPL training after completing A PPL or CPL beforehand.&lt;/p&gt;&#xA;" OwnerUserId="6920" LastEditorUserId="6920" LastEditDate="2015-01-23T22:36:40.493" LastActivityDate="2015-01-23T22:36:40.493" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11839" PostTypeId="1" CreationDate="2015-01-20T05:37:08.453" Score="14" ViewCount="12009" Body="&lt;p&gt;Assuming one  does not have a driver's license, is it possible for one to obtain a pilot's license to fly a helicopter? Cost is not the question here. I want to know if one can never obtain a driver's license (for ground, motor vehicles) &lt;strong&gt;and still be able to obtain a pilot's license to fly helicopters, planes, etc&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is applicable for the U.S. only.&lt;/p&gt;&#xA;" OwnerUserId="6921" LastEditorUserId="62" LastEditDate="2015-01-20T13:58:04.873" LastActivityDate="2015-01-23T00:03:41.867" Title="Can you fly a helicopter without a driver's license?" Tags="&lt;faa-regulations&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11841" PostTypeId="1" AcceptedAnswerId="11847" CreationDate="2015-01-20T06:09:43.320" Score="23" ViewCount="4304" Body="&lt;p&gt;Do runways of the airports have some special kind of tar or protective layer to avoid the wear and tear in comparison to that of the Highways as they need to handle the much high pressure and the weights than normal highways?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1896" LastEditDate="2015-01-20T15:48:54.693" LastActivityDate="2015-01-20T18:57:42.113" Title="Do runways need some special kind of tar or protective layer?" Tags="&lt;runways&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11842" PostTypeId="2" ParentId="11839" CreationDate="2015-01-20T06:17:43.410" Score="25" Body="&lt;p&gt;Here's a &lt;a href=&quot;https://www.youtube.com/watch?v=lpTxtRx2hxg&quot;&gt;a video&lt;/a&gt; where a CFI discusses this very question. There's no rule that says you need a driver's license to obtain a certificate to fly in the US. The real question is why you can't obtain a driver's license. If you have a medical problem that disqualifies you from driving, that will likely pose a far larger issue getting a medical to fly. Similarly, any drug or alcohol problem or conviction must be reported to the FAA. If your driver's license was suspended or revoked due to drug or alcohol, that must be reported as well. These issues are reviewed on a case-by-case basis, as the FAA wants to be satisfied that you will not try to fly while impaired. Beyond those types of problems, if you simply don't own a car and never wanted to learn to drive, nothing is stopping you from getting a license to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that you will need some sort of government-issued photo ID. A passport or state-issued non-driver ID should be fine. You might also run into the practical problem that it may be difficult to get to/from airports in many regions without driving, so you'd have to find alternate transportation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, there is one sort of connection between driver's licenses and flying in the US. Pilots with a valid driver's license &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-Sport-Pilot-Light-Sport-Aircraft-Final-Rule&quot;&gt;can fly Light Sport Aircraft&lt;/a&gt; without obtaining the otherwise-required third class medical certificate. A few rotorcraft (like &lt;a href=&quot;http://www.gyroplanepassion.com/LightSportAircraft.html&quot;&gt;this one&lt;/a&gt;) qualify as LSA. There are, however, significant restrictions on these operations, such as the requirement that they can't fly at night or carry more than one passenger. This rule does not override the medical requirements to fly, but requires the pilot to certify him/herself able to fly safely instead of receiving that certification from a Aviation Medical Examiner. In other words, if there's a reason you wouldn't be able to obtain a third class medical, then you are not allowed to fly a LSA using only a driver's license.&lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2015-01-20T06:17:43.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11843" PostTypeId="2" ParentId="11841" CreationDate="2015-01-20T06:49:15.697" Score="-3" Body="&lt;p&gt;Nothing special is needed for light aircraft.  Most don't even require a paved surface.  Western airliners  and military are happiest on thick concrete surfaces.  Most Russian airliners and military aircraft with their bigger wheels/tires can operate from dirt runways. &lt;/p&gt;&#xA;" OwnerUserId="6920" LastActivityDate="2015-01-20T06:49:15.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11844" PostTypeId="1" AcceptedAnswerId="11850" CreationDate="2015-01-20T06:59:25.137" Score="21" ViewCount="3794" Body="&lt;p&gt;Consider the case where the engine is started, aircraft taxies to the run-up area to do check, then it turns out that a magneto is bad, or there's a radio problem. The pilot wisely decides to abort the flight, and taxies back to parking. In the process, experience has been gained in taxiing, possibly ATC communication, the pre-flight, and good pilot judgement for the flight. There were no take-offs, landings or air time, but the aircraft was under the control of a PIC during taxi.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a long discussion about this on &lt;a href=&quot;http://www.pprune.org/private-flying/422593-logging-taxi-time-aborted-flight-2.html&quot;&gt;PPRuNe&lt;/a&gt;, with varying opinions either way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot;&gt;14 CFR 1.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flight time means:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Pilot time that commences when an aircraft moves under its own&#xA;  power for the purpose of flight and ends when the aircraft comes to&#xA;  rest after landing; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For a glider without self-launch capability, pilot time that&#xA;  commences when the glider is towed for the purpose of flight and ends&#xA;  when the glider comes to rest after landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The key phrases seem to be &lt;em&gt;for the purpose of flight&lt;/em&gt; (which seems to be satisfied - unless going for a VOR check, or moving the aircraft from one location to another), and &lt;em&gt;after landing&lt;/em&gt; (which, doesn't apply, because there was no airborne time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have there been any FAA determinations, rulings or enforcement actions made in this regard?&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2015-01-20T17:11:44.420" LastActivityDate="2017-08-18T19:33:55.797" Title="May time be logged for an aborted flight?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11847" PostTypeId="2" ParentId="11841" CreationDate="2015-01-20T07:35:57.910" Score="23" Body="&lt;p&gt;Airport designers may use any type of material, based on construction research status and local meteorological conditions. Pavements may be flexible or rigid. There is no single technique to protect against wear and tear, and none specific to airports, this is similar to regular road construction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Information on &lt;a href=&quot;http://onlinemanuals.txdot.gov/txdotmanuals/pdm/pavement_types.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;pavement types&lt;/a&gt; at &lt;a href=&quot;http://txdot.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Texas Dept of Transportation&lt;/a&gt;.&#xA;E.g. a rigid pavement:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VpMz6.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA provides advisories to help designers. ICAO requires airports to report their pavement characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gnbpz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.freep.com/story/news/local/michigan/wayne/2015/01/04/airport-needs-rebuild-million-runway/21236323/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Detroit Free Press&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA documentation related to pavement design:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/airports/engineering/pavement_design/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pavement Design &amp;amp; Construction&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5320-6&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport Pavement Design and Evaluation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;ICAO requires member states to report aerodrome-related aeronautical data, including pavement strength. The standardized method is known as the &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5335-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pavement Classification Number (ACN-PCN)&lt;/a&gt; method.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a critical characteristic of a pavement is the friction, this matter is refined in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/advisory_circular/150-5320-12C/150_5320_12c.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;Measurement, Construction, and Maintenance of Skid-Resistant Airport Pavement Surfaces&lt;/a&gt;. This document includes data on rubber removal frequency, e.g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/l0J8a.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Busy runway end:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k9til.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.bridgepointroadmarkings.com/services/line-removal/runway-rubber/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bridgepoint Road Markings Ltd&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A technique for rubber removal:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/byPoJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.waterblastingtechnologies.com/wp-content/uploads/2012/09/Stripe_Hog_SH8000_Runway_Rubber_Removal_72inchpass_2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Waterblasting Technologies&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This thesis describes how to optimize runway pavements in order to increase friction and how to remove rubber deposit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://uwspace.uwaterloo.ca/bitstream/handle/10012/6903/Pinto_Samantha.pdf?sequence=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Optimizing Airport Runway Performance by Managing Pavement Infrastructure&lt;/a&gt; by Samantha Theresa Pinto. Note that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rubber accumulation on a dry runway is generally not a problem since&#xA;  the rubber interaction between the aircraft tire and the rubber on the&#xA;  runway creates traction that may actually improve friction. However,&#xA;  in wet conditions, rubber accumulation leads to loss of friction on&#xA;  the runway by clogging the pavement texture and creating an especially&#xA;  slick surface with minimal drainage capability when the runway surface&#xA;  is wet. Additionally, rubber accumulation causing decreased friction&#xA;  values means pilots have less directional control of the aircraft than&#xA;  expected on a bare and dry runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-01-20T18:57:42.113" LastActivityDate="2015-01-20T18:57:42.113" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11848" PostTypeId="2" ParentId="2538" CreationDate="2015-01-20T07:57:43.310" Score="1" Body="&lt;p&gt;Australia only produces 1:1,000,000 WAC charts for the whole country.  The more detailed 1:500,000 VNC charts like we have in Canada are available only around major cities.  The VNC chart is similar to the US &quot;sectional&quot; chart.  VNCs &lt;a href=&quot;https://www.airservicesaustralia.com/store/coveragemaps.asp?pg=40&quot; rel=&quot;nofollow&quot;&gt;are available&lt;/a&gt; from Air Services Australia, the &lt;a href=&quot;http://www.airservicesaustralia.com/about/&quot; rel=&quot;nofollow&quot;&gt;state-owned entity&lt;/a&gt; responsible for airspace management and aeronautical information.&lt;/p&gt;&#xA;" OwnerUserId="6920" LastEditorUserId="4197" LastEditDate="2015-10-28T16:27:24.937" LastActivityDate="2015-10-28T16:27:24.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11849" PostTypeId="2" ParentId="11841" CreationDate="2015-01-20T09:03:52.717" Score="6" Body="&lt;p&gt;To withstand the heavy loads of heavy aircraft landing, the runway mainly needs sufficiently strong foundation and that can be done by simply making it sufficiently thick. Concrete is recommended for airport accepting very heavy aircraft like A380, but it's not always an option because concrete is very rigid and thus requires stable ground and some airport, like the new Hong Kong International Airport built partly on reclaimed land, don't have that luxury.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For surface wear, note that while a runway experiences heavier and faster movements, there is much fewer of them than on a busy motorway.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-20T09:03:52.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11850" PostTypeId="2" ParentId="11844" CreationDate="2015-01-20T12:01:29.030" Score="15" Body="&lt;p&gt;Interesting question, I found myself in exactly that position a couple of months ago (more on that below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, I found an FAA clarification on this, which is a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2007/lloyd%20-%20%282007%29%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;legal interpretation&lt;/a&gt; from 2007 and it partly answers your question. The questioner asked the FAA three questions about logging flight time (in a helicopter in this case); questions 1 and 2 are very close to yours. Question 1 is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;May a pilot log as &quot;flight time&quot; to qualify for a certificate or rating under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR Part 61&lt;/a&gt;, or for purposes of qualifying under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=87fe22fb45b370225eed0fc6d4ba13ba&amp;amp;node=se14.3.135_1243&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14&#xA;  CFR 135.243(b)(2)&lt;/a&gt;, that time accrued in a helicopter when the aircraft&#xA;  is sitting on the ground with the engine running and rotor blades&#xA;  turning, but the aircraft has not moved from its parking place and&#xA;  flight has not yet commenced?&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Question 2 is almost the same, but it asks about logging time after parking but when the engine is still running. I know that this is slightly different from your scenario, because you're asking about logging time &lt;em&gt;after&lt;/em&gt; the aircraft has moved from its parking place, but the FAA response says the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] flight time [...] commences the moment that [the aircraft] moves under its&#xA;  own power away from its parking place for the purpose of flight -&#xA;  whether departure is commenced by lifting off or taxiing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So according to that interpretation, you can start logging time as soon as you start taxiing but it goes on to say that you cannot log time after the aircraft lands. That means that your question is still a grey area, and if you want a definite answer then you should probably ask the FAA for your own interpretation. But my personal take is that the FAA is only concerned about people trying to cheat the system by sitting with the engine running, and for practical purposes you can log time as soon as you start taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And turning to the real-world situation, I don't think it matters at all. Every instructor and pilot I have ever met simply logs whatever time the Hobbs says, regardless of what happens in between. The FAA has absolutely no way to accurately verify what you're logging and there's a large degree of trust in the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my case, the AI gyro didn't spin up and although I didn't need that instrument (the planned flight was &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.3.7.3&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR&lt;/a&gt; in &lt;a href=&quot;http://en.wiktionary.org/wiki/CAVU&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAVU&lt;/a&gt; conditions) I elected not to fly anyway: better safe than sorry, and if one thing is broken it may be a symptom of a bigger problem. I taxied back with 0.2 on the Hobbs: I didn't log it (and the FBO didn't charge me). My thinking was simply that I didn't really 'fly' and 0.2 is irrelevant for all practical purposes. I'm sure that someone somewhere has found themselves 0.1 short of what they needed for a rating and really wished that they had that extra time, but if you ever find yourself in that position, it's no big deal to do a couple of turns in the pattern.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note: there is &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2004/kania%20-%20(2004)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;another FAA interpretation&lt;/a&gt; on this, but it looks like it only applies to part 121. They said yes, you can log it, but that's based on the assumption that after you taxi back to the gate, the airline finds a second aircraft and you fly that one to the original destination. They didn't say what happens if the flight is cancelled completely.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-08-18T19:33:55.797" LastActivityDate="2017-08-18T19:33:55.797" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11851" PostTypeId="2" ParentId="11839" CreationDate="2015-01-20T14:42:40.723" Score="5" Body="&lt;p&gt;In order to obtain a PPL in a glider, one only needs to be 16, which is younger than the age to get a driver's license in many states. For airplane and heli, it's 17, and there's no evidence that every 17-year-old has such a license.  So there doesn't seem to be any correlation between an actual drivers license and a pilots license, so long as the reasons for not having one aren't in violation of any other laws, regs, or decrees to which you're subject.  You must still provide appropriate identification.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two applicable FARs regarding disqualified for non-FAA-related legal or regulatory actions are 61.15/.16, which refer to alcohol and drugs, and 61.18, which refers to security disqualification. 15 and 16 don't apply, as you wrote.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;61.18, however, has to do with security threats. If the Transportation Security Administration (TSA) has notified the FAA in writing that you pose a security threat, then you would also be disqualified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If none of these apply, then you (or perhaps better, an aviation lawyer) can write the FAA's chief counsel and ask for an opinion. The relevant contacts are &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/contacts/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-21T13:47:17.417" LastActivityDate="2015-01-21T13:47:17.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11852" PostTypeId="1" CreationDate="2015-01-20T15:34:23.067" Score="2" ViewCount="1843" Body="&lt;p&gt;In ATR 72-500 FCOM document I found engine parameters including power settings as &quot;Reserve Take off&quot;. What does that mean?&lt;/p&gt;&#xA;" OwnerUserId="6927" LastEditorUserId="572" LastEditDate="2015-02-24T10:41:41.360" LastActivityDate="2015-02-24T10:41:41.360" Title="What does &quot;reserve take off&quot; mean in engine parameter documentation?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11853" PostTypeId="1" CreationDate="2015-01-20T15:53:22.420" Score="3" ViewCount="147" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Related question:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/q/2538/2143&quot;&gt;Where can I find GA VFR maps for Australia?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For various areas of the world, where are authoritative General Aviation VFR maps, charts, and so on available on the web?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2017-01-30T15:57:40.217" Title="Where can I find a canonical list of sources for worldwide digital GA VFR maps?" Tags="&lt;general-aviation&gt;&lt;visual-flight-rules&gt;&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2020-09-22T04:48:37.033" ContentLicense="CC BY-SA 3.0" />
  <row Id="11854" PostTypeId="2" ParentId="11853" CreationDate="2015-01-20T15:53:22.420" Score="1" Body="&lt;p&gt;&lt;em&gt;This answer is a Community Wiki. Please edit as appropriate.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Australia&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ozrunways.com/&quot; rel=&quot;nofollow&quot;&gt;OzRunways.com&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;United States&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/VFRCharts/&quot; rel=&quot;nofollow&quot;&gt;VFR Charts&lt;/a&gt; from the U.S. Federal Aviation Administration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2015-01-20T15:53:22.420" CommentCount="0" CommunityOwnedDate="2015-01-20T15:53:22.420" ContentLicense="CC BY-SA 3.0" />
  <row Id="11855" PostTypeId="2" ParentId="11852" CreationDate="2015-01-20T16:02:04.420" Score="2" Body="&lt;p&gt;I've seen this mentioned in &lt;a href=&quot;http://www.planes.cz/cs/clanky/485/&quot; rel=&quot;nofollow&quot;&gt;story&lt;/a&gt; (unfortunately in Czech) about flying in Bhutan on ATR-42 (a smaller version of the same aircraft). Basically in most situation it is recommended to use less then maximum rated power to reduce wear of the engine and that setting is marked as “take off” and the maximum rated power is only used in high density altitude (hot and high) conditions or very short runways and is labelled “reserve take off”.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most other aircraft don't have setting labelled like this, but taking off at less than maximum rated power is common. It is called “derated” or “flex” take-off.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-20T16:02:04.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11856" PostTypeId="2" ParentId="11852" CreationDate="2015-01-20T16:48:55.880" Score="1" Body="&lt;p&gt;Engines sometimes have a &amp;quot;reserve power range&amp;quot; (or &amp;quot;emergency power&amp;quot;) which is only used when the extra power is absolutely needed. This is higher than the &amp;quot;takeoff power&amp;quot; setting that is generally a 5-minute limit on certain parameters for regular takeoffs. ATR is advertising a &amp;quot;reserve take-off torque option&amp;quot; which allows higher power at takeoff. This allows using some of the extra power in difficult takeoff situations. &lt;a href=&quot;http://www.atraircraft.com/products_app/media/pdf/Brochure-ATR-600-SeriesBD.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;From the materials for the ATR 72-600&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;ATR has developed the Take-off at &amp;quot;Reserve Take-off Torque&amp;quot; option to improve take-off capabilities on very short runways or in case of near obstacles.&lt;/p&gt;&#xA;&lt;p&gt;... ATR and P&amp;amp;WC have jointly worked to provide on request 4.5% higher thermodynamic power at take-off and max continuous ratings. This results in:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Increase of climb gradient in hot and high conditions leading to takeoff weight improvement of around 500 Kg (1,100 lb).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Example: + 500 kg from Bogota airport (8,360ft and ISA+20°C) + 1,000 ft higher one engine out net ceiling.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-20T18:29:58.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11857" PostTypeId="1" AcceptedAnswerId="11860" CreationDate="2015-01-20T17:06:52.220" Score="29" ViewCount="21176" Body="&lt;p&gt;I always assumed that big runways are flat (or more specifically straight: they might have a slight slope in either direction), but while watching some &lt;a href=&quot;https://www.youtube.com/watch?v=lP35ULU6IcQ&quot; rel=&quot;noreferrer&quot;&gt;crosswind landing footage&lt;/a&gt; shot at Birmingham Airport I noticed that the runway looks really uneven, and based on the videos it looks like this hinders safe landing especially in adverse weather conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/12oe4.jpg&quot; alt=&quot;Runway&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How common are uneven runways like this?&lt;/li&gt;&#xA;&lt;li&gt;Does an uneven runway make landings more difficult?&lt;/li&gt;&#xA;&lt;li&gt;Is there any standard on how flat a runway needs to be? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6928" LastEditorUserId="65" LastEditDate="2015-01-20T17:24:12.880" LastActivityDate="2015-04-05T16:09:51.863" Title="How flat does a runway need to be?" Tags="&lt;runways&gt;&lt;regulations&gt;&lt;airport-design&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11858" PostTypeId="2" ParentId="11827" CreationDate="2015-01-20T18:02:53.780" Score="8" Body="&lt;p&gt;The pilot must be trusted over anything else (and even Airbus planes accept any input in Direct law, Normal law doesn't always apply). Any unforeseen situation may arise during the flight. Computers cannot handle every abnormal situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example of such a situation is the case of &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Express_Flight_705&quot;&gt;FedEx Flight 705&lt;/a&gt;. The pilots were attacked with a sledgehammer by a hijacker. They would probably be dead, if not for the extreme maneuvers attempted. They pushed their DC-10 plane far beyond its limits (bank angle up to 140°, overspeed near mach 1.0). Had the computer prevented them to do this, the plane may have crashed and they'd be all dead.&lt;/p&gt;&#xA;" OwnerUserId="6929" LastEditorUserId="1696" LastEditDate="2015-01-20T18:09:53.053" LastActivityDate="2015-01-20T18:09:53.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11859" PostTypeId="2" ParentId="11827" CreationDate="2015-01-20T18:49:15.803" Score="2" Body="&lt;p&gt;Let's think of this from a different angle. Sometimes it's not just pilot input that would put the plane into an unsafe attitude. Now if the plane is forced into a heavy bank, climb, or dive through external forces but the pilot is limited in what response he can give to the plane to adjust....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also think of high fog and communication issues. and two planes are in risk of collision. The plane says to the pilot &quot;nope you can't bank because that would put us at risk&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under normal flying conditions, you'd want to fly within operating parameters. But when the proverbial stuff hits the fan, you want full control to attempt to avoid a tragedy.&lt;/p&gt;&#xA;" OwnerUserId="6930" LastActivityDate="2015-01-20T18:49:15.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11860" PostTypeId="2" ParentId="11857" CreationDate="2015-01-20T18:52:23.660" Score="21" Body="&lt;p&gt;Given that the runway is over 3000m, those undulations don't look very big. I doubt they had much to do with the landings in the video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to make something that long completely flat.  The FAA has advisory circulars for all sorts of stuff in and around an airport.  One does cover flatness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5300-13A-chg1-interactive.pdf&quot;&gt;Airport Design Advisory Circular&lt;/a&gt;  Page 77 has recommendations on gradients including:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Vertical curves for longitudinal grade changes are parabolic. The length&#xA;  of the vertical curve is a minimum of 300 feet (91 m) for each 1.0 percent of change. A vertical&#xA;  curve is not necessary when the grade change is less than 0.40 percent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, I could not find measurements of the undulations at BHX online, and I'm not going to estimate it from that photo.  Would be nice to know how much above or below these particular recommendations it is.  &lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-01-20T18:52:23.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11861" PostTypeId="1" CreationDate="2015-01-20T19:27:54.133" Score="15" ViewCount="2742" Body="&lt;p&gt;There is info about straight edge wings, swept back wings, swept forward wings, delta wings.&#xA;Is there also info about a Delta wing with a straight leading edge and a tapered trailing edge, the point rearwards, like a manta ray?&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="31425" LastEditDate="2019-12-20T17:41:21.363" LastActivityDate="2019-12-20T17:41:21.363" Title="How would an Inverted Delta Wing planform behave, Straight part forward? Are there wings shaped this way?" Tags="&lt;wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="11862" PostTypeId="2" ParentId="11861" CreationDate="2015-01-20T19:56:21.927" Score="15" Body="&lt;p&gt;To answer your second question first: &lt;strong&gt;Yes&lt;/strong&gt;, these are mainly used for &lt;a href=&quot;http://www.msacomputer.com/flyingboats-old/wig/wig.html&quot; rel=&quot;noreferrer&quot;&gt;ground-effect craft&lt;/a&gt;. The idea is to have positive angle of attack, a tapered wing and a trailing edge with &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)&quot; rel=&quot;noreferrer&quot;&gt;constant, low distance from the ground&lt;/a&gt;. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9702/is-the-sweep-angle-of-an-inverted-wing-zero-degrees&quot;&gt;This question&lt;/a&gt; covers their sweep angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SbY0U.jpg&quot; alt=&quot;The RFB X-114 ground-effect craft&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/RFB_X-114&quot; rel=&quot;noreferrer&quot;&gt;RFB X-114&lt;/a&gt; ground-effect craft. Forward is right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing would behave just like an ordinary, forward swept, low aspect ratio wing. It would have a &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;small lift curve slope&lt;/a&gt; and a lousy stall behavior, because the low tip chord will make the tips stall first, causing the whole wing to roll. Unfortunately, the low leading edge sweep will prevent vortex lift, which is a typical feature of regular delta wings, to develop, so the stall angle will be only little higher than that of a straight wing with the same aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kisTO.jpg&quot; alt=&quot;Top view of a manta ray&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Manta rays are more diamond-shaped, so their &quot;wing&quot; has positive leading edge sweep and almost zero quarter-chord sweep. Their stall behavior would also be nasty if they were rigid, but the wings are actually fins and used for propulsion, not lift, so stall does not mean that the fish plunges to the ground. The picture above shows an Atlantic manta and was shamelessly copied from Wikipedia.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-07T20:25:53.297" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11863" PostTypeId="2" ParentId="11827" CreationDate="2015-01-20T20:15:07.003" Score="1" Body="&lt;p&gt;Your question can be answered by a simple reductio ad absurdum argument. If the airplane knew what inputs were safe, then why have any pilot at all?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact modern commercial flights already pretty much fly automatically, and they do have mechanisms to avoid potentially dangerous inputs. The problem is that failure detection is hard because when something has failed, the system (by the definition of failure) does not have valid data to make decisions. It is the same reason crazy people may not know they are crazy. The pilot is there to make decisions in the face of ambiguity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course sometimes the pilot makes the wrong decision too, and the airplane crashes. See &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow&quot;&gt;Air France 447&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But more often they make the right decision, and everyone lives. See &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow&quot;&gt;the Gimli Glider&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1982" LastEditorUserId="1982" LastEditDate="2015-01-20T21:08:06.873" LastActivityDate="2015-01-20T21:08:06.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11864" PostTypeId="2" ParentId="9243" CreationDate="2015-01-20T21:08:15.793" Score="1" Body="&lt;p&gt;Any time the question is &lt;em&gt;&quot;why don't we have...&quot;&lt;/em&gt;, the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, &amp;amp; utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting a complex break-apart &amp;amp; parachute system on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. All that extra weight has to be flown around, requiring fuel. They would need regular maintenance checks, which is another cost. And they would only be useful very, very infrequently (on most planes, it would &lt;strong&gt;&lt;em&gt;never&lt;/em&gt;&lt;/strong&gt; be used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This same line of reasoning goes for &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11584/why-movable-thrusters-are-not-used-in-airplanes/&quot;&gt;why don't more airplanes have rocket thrusters&lt;/a&gt;&quot;, &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7768/why-dont-airliners-carry-radar-jamming-technology-or-missile-counter-measures&quot;&gt;why don't planes have anti-missile systems&lt;/a&gt;&quot;, &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9818/airbags-in-aircraft-is-that-just-a-military-thing&quot;&gt;why don't planes have airbags&lt;/a&gt;&quot;, and many other random items.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-01-20T21:08:15.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11865" PostTypeId="1" CreationDate="2015-01-20T22:59:17.570" Score="1" ViewCount="936" Body="&lt;p&gt;Do the pilots of the plane simply reverse thrust of the engines after touchdown or are there brakes on the landing wheels that slow the plane just like a car? Or a combination of both?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about prop-planes?&lt;/p&gt;&#xA;" OwnerUserId="6935" LastActivityDate="2015-01-21T02:01:43.663" Title="How does a typical passenger jet come to a stop when it lands" Tags="&lt;landing&gt;&lt;thrust-reverser&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-01-21T02:08:31.957" ContentLicense="CC BY-SA 3.0" />
  <row Id="11866" PostTypeId="2" ParentId="11857" CreationDate="2015-01-20T23:10:31.830" Score="24" Body="&lt;p&gt;As an anecdotal answer to your first two questions, paved runways used by air carriers that have obviously noticeable vertical curves are a minority but not uncommon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless they've redone the runway at Stansted, north of London, there's a significant hump in the middle. I used to operate through it at night in the early 1990s. As a bit of fun, we'd arrange legs so that a new first officer would have the leg into Stansted. On final at night the hump was not noticeable. However, when you touched down, the runway lights along the last half of the runway would disappear, at which point the captain would observe, &quot;Hmm, not much runway left.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you define a runway simply as a strip of land regularly used by aircraft, there's a whole lot of them that have vertical curves, and many with horizontal bends as well. It's gone now, but there used to be a strip at a lumber mill in North Fork, California, that had a 10-15 degree bend in the middle. McKenzie Bridge airfield just upriver from my home in Oregon has a steep incline on the east end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landings and takeoff on uneven runways are not significantly more complex than on straight runways. If the runway qualifies as an uphill/downhill runway, you generally takeoff downhill and land uphill. Touching down on the downside of a hump can make your landing feel a little softer than otherwise. Touching down on the upside of a hump makes it a little harder than otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accommodating a horizontal curve is more challenging. It's worth remembering, though, that seaplanes often use a curved takeoff run. &lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-01-20T23:16:19.647" LastActivityDate="2015-01-20T23:16:19.647" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11867" PostTypeId="2" ParentId="371" CreationDate="2015-01-21T00:33:48.413" Score="0" Body="&lt;p&gt;Some EAA chapters share ownership of homebuilt airplanes and members can build flight time by using these planes.  Flight time is flight time and in many cases it doesn't matter that it's a homebuilt (for example, cross-country flying, navigation practice, tail-wheel practice, seaplane practice, basic aerobatics, etc). Homebuilts also give an opportunity to do some aircraft maintenance &amp;amp; repair. It's all good experience.&lt;/p&gt;&#xA;" OwnerUserId="6920" LastActivityDate="2015-01-21T00:33:48.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11868" PostTypeId="2" ParentId="673" CreationDate="2015-01-21T00:46:39.613" Score="3" Body="&lt;p&gt;Most windows (Boeing) are a triple layer of plexiglas -&#xA;Cabin air circulates between panes for defogging -&#xA;Except the windows found on cargo doors (electrical heat instead) -&#xA;Elasticity is the main reason why they are strong -&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Windshields are different, must resist to bird strikes and be heated -&#xA;One inch or more in thickness and special optical corrections -&#xA;A windshield pane for a 727 was $10,000 in the 1980s...!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that some airplanes have two different Vmo -&#xA;Because of windshield bird strike resistance -&#xA;As an example, some Learjets -&#xA;Vmo (low altitude where birds are) is 305 KIAS -&#xA;Vmo (high altitude, above FL 140) is 358 KIAS -&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did fly as Learjet instructor in the early 1970s -&#xA;I was told the windshields of the 24/25 were &quot;birdproof&quot; -&#xA;Could resist a 4 lbs bird hitting the windshield at 350 mph -&#xA;I wondered if it could resist a 350 lbs turkey at 4 mph...?&#xA;ROFL -&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One note also about a fire axe -&#xA;If you wish to make a hole to escape, do not try windows -&#xA;Windows are extremely resistant -&#xA;It is better to use a fire axe against metal (fuselage skin) -&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at UK-CAA airplanes and &quot;cut here&quot; frames on side of fuselages -&#xA;Airfield firemen are knowledgeable about not trying to &quot;break&quot; windows -&#xA;And would open fuselages within the &quot;cut here&quot; frame indications - &lt;/p&gt;&#xA;" OwnerUserId="6936" LastActivityDate="2015-01-21T00:46:39.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11869" PostTypeId="2" ParentId="11865" CreationDate="2015-01-21T02:01:43.663" Score="1" Body="&lt;p&gt;The main components that stops the aircraft are the brakes and spoilers and secondary would be the reverse thrust and flaps. &#xA;When a airplane lands it still has some velocity and that velocity still creates lift. &#xA;When the spoiler goes up it stops the wing from create lift and sits the plane on the ground, so the brakes have more efficiency.&#xA;Some aircrafts would need twice or three times longer runways to stop with the spoiler inop. &#xA;As a secondary resource there are the reverse thrust and the flaps, witch when is full down creates more drag than lift and helps the aircraft to stop. &lt;/p&gt;&#xA;" OwnerUserId="4052" LastActivityDate="2015-01-21T02:01:43.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11871" PostTypeId="1" AcceptedAnswerId="11875" CreationDate="2015-01-21T05:34:52.523" Score="21" ViewCount="4613" Body="&lt;p&gt;Once a commercial aircraft is in the cruise phase, who determines the speed of the aircraft? &#xA;Do pilots have the authority to fly at up to the maximum permissible speed of that plane, or does ATC decide on that depending on the approximate time it will take to reach the destination? Is it stated in the flight plan that the pilot cannot go beyond some specific speed even if the aircraft is capable of it?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-01-21T11:09:16.840" LastActivityDate="2015-01-21T18:37:15.300" Title="Who decides how fast commercial aircraft fly: the pilots or ATC?" Tags="&lt;air-traffic-control&gt;&lt;aircraft-performance&gt;&lt;airline-operations&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11872" PostTypeId="2" ParentId="11871" CreationDate="2015-01-21T05:41:45.510" Score="-7" Body="&lt;p&gt;ATC is providing collision separation services only. It is the responsability of the pilot to operate the airplane and to keep it under a safe flight envelope. So, speed:pilot, Heading-altitude:ATC :)&lt;/p&gt;&#xA;" OwnerUserId="6808" LastActivityDate="2015-01-21T05:41:45.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11873" PostTypeId="2" ParentId="11871" CreationDate="2015-01-21T05:58:14.117" Score="11" Body="&lt;p&gt;Pilots will mostly set the speed they want. In cruise, the planes tend to be further apart, and speed is less critical. Different planes fly at different speeds, and ATC usually uses altitude and heading as the primary means to separate them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, ATC will sometimes ask for different speeds as another way to separate aircraft. If a fast plane that wants to climb is underneath a slower plane, ATC may have the slower plane slow down a bit, and the faster plane speed up a bit so the faster plane can get far enough ahead to climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the plane nears its destination, speed becomes more likely to be a factor. If there are delays at the destination, ATC may tell the pilots to slow down to minimize time spent in a holding pattern. This may also serve to sequence planes in for arrival, where ATC may ask for faster or slower speeds. Speed restrictions are much more common in arrival, which &lt;a href=&quot;https://aviation.stackexchange.com/a/11875/1696&quot;&gt;SentryRaven's answer&lt;/a&gt; describes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-01-21T18:37:15.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11874" PostTypeId="2" ParentId="11658" CreationDate="2015-01-21T06:48:07.720" Score="-1" Body="&lt;p&gt;Though an analysis of a single crash is hardly decisive, its findings did support a study by Popular Mechanics, carried out in 2007. The magazine analysed all crashes since 1971 and found that those in rear seats (behind the wing’s trailing edge) were safest – survival rates were 69 per cent as opposed to 56 per cent over the wing and 49 per cent for those at the front of the plane.&lt;/p&gt;&#xA;" OwnerUserId="6908" LastActivityDate="2015-01-21T06:48:07.720" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11875" PostTypeId="2" ParentId="11871" CreationDate="2015-01-21T07:12:35.183" Score="21" Body="&lt;p&gt;ATC can assign speeds en-route for separation or in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_Control_Area&quot; rel=&quot;nofollow noreferrer&quot;&gt;TMA area&lt;/a&gt; for sequencing aircraft onto the approach. Speeds en-route in upper sectors are assigned using &lt;a href=&quot;http://en.wikipedia.org/wiki/Mach_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mach numbers&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R: &quot;DLH123, maintain speed Mach .78&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;In the TMA area, aircraft are sequenced for an approach and reduced to similar speeds to maintain lateral separation. These restrictions can be paired with conditions, until when the speed needs to be maintained:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R: &quot;BER456, reduce speed 210 knots&quot;&#xA;R: &quot;BER456, cleared ILS approach runway 24, &#xA;    maintain 170 knots indicated until outer marker / 5 DME&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Certain approach or arrival charts list maximum speeds for certain turns, marked with &lt;code&gt;MAX 210 KIAS&lt;/code&gt;, indicating that this turn should not be flown with more than 210 KIAS to make the radius.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed restrictions imposed by ATC need to be maintained until cancelled by the ATC unit:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R: &quot;DLH123, no speed restrictions / resume normal speed&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The pilot however is responsible for ensuring a safe flight and can report that he is unable to follow the instructions due to performance limitations. &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A: &quot;DLH123, unable to comply, indicated airspeed will be 150 knots&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;There is also legal considerations when it comes to aircraft speeds, such as general rules for traffic below certain altitudes or in some jurisdictions, only for certain airspace classes (related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1294/what-is-the-speed-limit-in-european-airspace?&quot;&gt;What is the speed limit in European Airspace&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1117&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA CFR 91.117&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.117   Aircraft speed.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.gesetze-im-internet.de/luftvo/anlage_5_75.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;German LuftVO&lt;/a&gt; however rules that a speed limit of 250 KIAS below FL100 only applies to VFR and IFR aircraft in airspaces class D,E,F,G and only to VFR aircraft in airspace class C. IFR aircraft in airspace class C do not have a speed limitation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding the general authority over a flight, see the related question:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7915/who-has-the-higher-authority-the-pilot-in-command-or-atc/7917#7917&quot;&gt;Who has the higher authority, the pilot in command or ATC?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-01-21T13:17:23.653" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="11876" PostTypeId="2" ParentId="11827" CreationDate="2015-01-21T09:48:20.853" Score="3" Body="&lt;p&gt;Another thing to consider is that knowledge required for controlling the aircraft is increasing with such systems in place.&lt;/p&gt;&#xA;&lt;p&gt;There nearly was a plane crash in Germany some years ago (see &lt;a href=&quot;https://www.youtube.com/watch?v=ueJeC2pxxbM&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; showing the landing), when a plane was landing during strong side winds. The problem was that the flight controls reacted differently when the plane touched ground or not. That was not known by the pilots. They managed the situation, but it could have been easier for them with knowing that behavior. This behavior even was not documented in the manual.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;EDIT:&lt;/em&gt;&lt;br /&gt;&#xA;From the &lt;a href=&quot;http://www.bfu-web.de/EN/Publications/Investigation%20Report/2008/Report_08_5X003_A320_Hamburg-Crosswindlanding.pdf?__blob=publicationFile&quot; rel=&quot;nofollow noreferrer&quot;&gt;investigation report&lt;/a&gt; (thanks to @DeltaLima):&#xA;Section 3.1&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The pilots could not have been aware of the specific flight system control response characteristics during a landing with a gusty crosswind und were, therefore, unable to incorporate it into their decision taking process.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And later on in this section&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;• When the left main landing gear first touched the runway, the lateral control system condition thus met all the requirements for the transition from Flight Mode to Ground Mode, so, the system switched from lateral Flight Mode to lateral Ground Mode even though the aircraft was once again in the air.&lt;/p&gt;&#xA;&lt;p&gt;• The aircraft was designed so that the effect of lateral controls (along the longitudinal axis) would reduce by about one half of full deflection as soon as one main landing gear touched down.&lt;/p&gt;&#xA;&lt;p&gt;• The reduced effect of controls was not documented in the system description and was unknown to pilots or the training department.&lt;/p&gt;&#xA;&lt;p&gt;• During the landing, the aircraft's system behaviour contributed to a flight attitude which was unintended and undesired by the pilots and ground contact with the wingtip could not be prevented&#xA;anymore.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6940" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-21T11:07:58.897" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11878" PostTypeId="2" ParentId="7915" CreationDate="2015-01-21T18:49:39.800" Score="0" Body="&lt;p&gt;The pilot in command (PIC) always has the final say and decision making power. A pilot can reject ANY controller instruction. However, if a pilot rejects an instruction and it later turns out that it was done in a reckless manner or for a blatantly wrong reason the FAA will revoke the pilot's license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot rejects a controller instruction, it is the duty of the controller to react appropriately and make any necessary changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's illustrate this with an extreme example: a Cherokee is in the pattern and has not yet been given a landing clearance. The controller tells the Cherokee &quot;You are number 2 behind the Arrow&quot; (which has been given a clearance). The Cherokee now says &quot;Negative, I am landing right now on three four, number one&quot; and he zooms in front of the Arrow, completely violating the controller instruction and landing without a clearance. What the controller will do is tell the Arrow N12345, &quot;Arrow 345 abort landing, assume heading zero niner zero IMMEDIATELY!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it later turns out that there was a fire on the Cherokee, then no action will be taken. If it turns out the pilot of the Cherokee was just trying to get to a business meeting on time, then his license will be revoked.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for the dispute between ground control and the pilot in question from LiveLeak, apparently the pilot thought the taxi route was poorly chosen or not correctly spoken. The article is incorrect in many of its details (you don't land on taxiways obviously!) What apparently happened is that the controller was planning to use Mike for a landing aircraft and directed the Delta pilot to use Lima--a longer route. The pilot probably thought the landing aircraft was far away and that he would be long gone before the other aircraft landed, so he thought the controller was being a jerkoff by making him take the long way around. In a situation like this courtesy dictates following ground control, but the pilot was within his rights to stay on Mike. I doubt the incident was reported, but if it had been the pilot would have been cleared in all likelihood, because all he would have to do is show that the landing aircraft arrived long after he was gone, thereby showing the controller to have had bad judgement. The pilot would only be penalized if his actions could be shown to compromise safety, which is not the case here, since in the worst case scenario the only outcome is that the landing aircraft might have to wait a little longer--not a safety issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to clarify the &quot;authority&quot; question here with regards to the recording: if you listen you will hear the pilot order &quot;Route on Mike&quot;. This basically means he is rejecting the Lima instruction of the controller and ordering him to re-route on Mike. No question who is in charge here.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-01-21T20:02:12.533" LastActivityDate="2015-01-21T20:02:12.533" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11881" PostTypeId="2" ParentId="11827" CreationDate="2015-01-21T22:15:09.050" Score="3" Body="&lt;p&gt;One of the problems with commercial aircraft is the sheer number of hours of flight that any given aircraft type will see and the vast number of different conditions and failures that will inevitably arise during all that flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had the job of writing the software that validated the control laws for the center of gravity management systems of several of these beasts. There's really no way to completely analyse all possible 'modes of flight'. The FCGMS system wasn't quite in the same category with the flight controls, but it WAS a 'safety of flight critical system'. There was a lot of validating involved, and this was just purely functional test, not all the vast array of unit level testing that went into the flight software. The thing is you have 20 boxes on these planes, all doing critical stuff, all built by different people, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end someone has to be able to take hold of the stick and PULL UP! when its required and get a direct response. Its quite true that this capability might be as often detrimental, but you just cannot and never will be able to, completely analyse code and know what it will do when pieces are falling off the airplane. &lt;/p&gt;&#xA;" OwnerUserId="6949" LastActivityDate="2015-01-21T22:15:09.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11883" PostTypeId="2" ParentId="11827" CreationDate="2015-01-22T01:12:15.417" Score="-2" Body="&lt;p&gt;Pilots want to have control over the aircraft. Personally, if I was an ATP I would never fly an automated FBW aircraft like an Airbus for that exact reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You don't to be in a spin or death spiral and then find out you can't get out of it because &quot;the computer will not allow that input&quot;, and trust me if you are in an aircraft that goes into a spin you most definitely want the pilot to have FULL control over the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may think: if the computer is controlling the aircraft it will never enter a spin. Not so. Some thunderstorms can arise very quickly and unexpectedly and are so violent they can force the aircraft into a spin or other attitude which the computer has zero chance of reacting to correctly. &quot;Good&quot; computers turn themselves off at that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most advanced FBW aircraft have a feature called &quot;automated recovery&quot; which allows them to automatically recover from some stall conditions, but in extreme conditions the changes in attitude will be happening so fast that you need a human to do it.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-22T01:12:15.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11884" PostTypeId="1" AcceptedAnswerId="11891" CreationDate="2015-01-22T03:48:42.687" Score="15" ViewCount="2544" Body="&lt;p&gt;I know that the nacelles around the aircraft engines are actually a housing and are generally lightweight and have may components like inlet cowl, fan cowl, etc., but do they help in reducing the engine sound as well or are they just for housing? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if they help in reducing the sound, then how much % of sound has been reduced by them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any quantitative analysis available for that which can show that without housing engines were creating sound at X dB, and after nacelle and proper housing of all other components, the sound has been decreased to Y dB?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-05-08T14:45:46.923" LastActivityDate="2015-10-23T13:28:55.213" Title="Do nacelles around aircraft engines help in reducing the engine sound?" Tags="&lt;engine&gt;&lt;noise&gt;&lt;nacelle&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11886" PostTypeId="2" ParentId="11884" CreationDate="2015-01-22T04:57:15.270" Score="1" Body="&lt;p&gt;The nacelles themselves reduce sound just by being another barrier before the sound gets to you for the most part. It's there to provide airflow around engine components, better aerodynamics, protection from elements, and depending on what kind of engine it is, it &quot;may&quot; help with noise reduction some (Turbofan).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On turbine engines, &lt;a href=&quot;https://engineering.purdue.edu/~propulsi/propulsion/jets/basics/noise.html&quot; rel=&quot;nofollow&quot;&gt;there are exhaust airflow options that do suppress the noise&lt;/a&gt;. This is not a nacelle, it's a noise suppression nozzle.  &lt;/p&gt;&#xA;" OwnerUserId="6950" LastEditorUserId="65" LastEditDate="2015-01-22T15:26:45.120" LastActivityDate="2015-01-22T15:26:45.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11887" PostTypeId="1" AcceptedAnswerId="11913" CreationDate="2015-01-22T05:00:00.967" Score="4" ViewCount="449" Body="&lt;p&gt;I remember when the first AirFones were put into service in 1990s and marveled at who would be rich enough to pay $7/min for air to ground phone service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though every seat eventually had an AirFone, I cannot once recall seeing one in use (except in movies) in twenty years of flying (in economy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know they're being pulled out now, but did AirFones ever make a profit? Who paid for their installation, was it the airlines or did GTE etc pay for everything?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="19" LastEditDate="2015-02-23T15:53:35.790" LastActivityDate="2015-02-23T15:53:35.790" Title="Did AirFone ever make money?" Tags="&lt;radio-communications&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11888" PostTypeId="2" ParentId="11884" CreationDate="2015-01-22T06:14:27.107" Score="7" Body="&lt;p&gt;As you have correctly mentioned, the term Nacelle generally refers to a number of sections around an aircraft engine (In the context of turbofan aircraft engines). This generally the structures formed by the Inlet, Fan Cowl, Thrust Reverser and the Exhaust.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nacelle does perform the basic function of a housing for all these subassemblies which means it contributes to protection of the engine from the elements and the environment from the engine (Say a blade failure). But its major function is to provide an aerodynamic body which can house the mechanicals of the engine, the pneumatic ducts, fuel lines and electrical wiring.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nacelle can therefore provide noise reduction by reducing the drag-noise which would be otherwise generated. This is through the aerodynamic design and the various features built into the subassemblies such as Acoustic Liners used extensively througout the nacelle which convert acoustic energy into small amounts of heat. This is a major source of noise-reduction in modern aircraft engines.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exhausts are the biggest culprits when it comes to aircraft engine noise and as such, the exhausts are designed to create a 'mixing' area where hot air from the exhaust is mixed with ambient air to reduce the exhaust noise.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess I'm just trying to say that the nacelle is formed of these various subassemblies and therefore their individual contribution towards noise reduction is very important. As far as a quantitative study on the reduction of noise, I could not locate any as therefore can only manage to answer the first part of your question.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sidenote: Modern Inlets also use Laminar-flow design (777X for example) which contribute to immense fuel savings and very minor drag-noise reduction (Probably negligible).&lt;/p&gt;&#xA;" OwnerUserId="4435" LastActivityDate="2015-01-22T06:14:27.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11889" PostTypeId="1" CreationDate="2015-01-22T06:58:24.107" Score="0" ViewCount="8198" Body="&lt;p&gt;Where can I find the various operating limitations of the &lt;a href=&quot;http://en.wikipedia.org/wiki/ATR_72&quot; rel=&quot;nofollow&quot;&gt;ATR 72-500&lt;/a&gt;? Is there any document that lists them?&lt;/p&gt;&#xA;" OwnerUserId="6927" LastEditorUserId="62" LastEditDate="2015-01-28T16:12:46.270" LastActivityDate="2017-09-29T14:57:48.843" Title="Where can I find the various operating limitations of the ATR 72-500?" Tags="&lt;aircraft-limitations&gt;&lt;atr-72&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2020-07-07T17:04:32.343" ContentLicense="CC BY-SA 3.0" />
  <row Id="11890" PostTypeId="1" AcceptedAnswerId="11894" CreationDate="2015-01-22T07:24:17.313" Score="2" ViewCount="628" Body="&lt;p&gt;I know in mostly all of the seaborne landings on the Naval warships is done using Arresting Gear and there are some land based airfields also which used arrested gear methodology but do any aircraft specifically military ones (just the fighter jets)can be stopped using this or there is something specific feature in an aircraft which makes it Arresting gear compatible?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-02-12T21:07:11.240" LastActivityDate="2015-02-12T21:07:11.240" Title="Can any military aircraft (only fighter jets not the military cargo ones) be stopped using Arresting Gear technique?" Tags="&lt;military&gt;&lt;arresting-gear&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11891" PostTypeId="2" ParentId="11884" CreationDate="2015-01-22T07:30:39.437" Score="19" Body="&lt;p&gt;Take a modern &lt;a href=&quot;http://web.stanford.edu/~cantwell/AA283_Course_Material/GE90_Engine_Data.pdf&quot; rel=&quot;noreferrer&quot;&gt;turbofan&lt;/a&gt;: The tips of the fan run at &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;approximately Mach 1.5&lt;/a&gt;. We know from &lt;a href=&quot;https://aviation.stackexchange.com/questions/21683/did-the-xf-84h-thunderscreech-really-cause-900-sonic-booms-per-minute&quot;&gt;unducted props that supersonic tips make them very noisy&lt;/a&gt;. The same turbofan without the shroud would be extremely noisy, too. &lt;a href=&quot;http://www.rolls-royce.com/sustainability/performance/casestudies/noise_technology/&quot; rel=&quot;noreferrer&quot;&gt;Acoustic liners on the inside of the fan shroud&lt;/a&gt; have major contribution in suppressing this noise source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there is more: The nacelle also makes it possible to put an intake in front of the fan which helps to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;equalize flow conditions&lt;/a&gt; over the cross section of the intake and to &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;accelerate or slow the flow of air&lt;/a&gt; to just the right amount for the engine. Without the intake, the engine would suffer from frequent compressor stalls and surges, so the nacelle in effect widens the operating conditions and avoids those &lt;a href=&quot;https://aviation.stackexchange.com/questions/7799/why-do-jet-engines-sometimes-spit-out-flames-after-ingesting-birds&quot;&gt;noisy incidents&lt;/a&gt;, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important source of noise is the nozzle: Here the hot, fast gas from the engine is ejected into the surrounding flow, and the mixing of both creates most of the &lt;a href=&quot;http://adg.stanford.edu/aa241/noise/noise.html&quot; rel=&quot;noreferrer&quot;&gt;engine noise&lt;/a&gt;. Note that noise increases with the sixth to eighth power of jet velocity, so the most dramatic noise reduction is possible with higher bypass ratio engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rp90i.gif&quot; alt=&quot;Plot of exhaust noise level over jet velocity&quot;&gt;&#xA;Diagram from the Stanford web page linked above. The jet velocity is in ft/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By serrating the trailing edge of the nozzle, this mixing process can be slowed down somewhat and the &lt;a href=&quot;http://www.nasa.gov/topics/aeronautics/features/bridges_chevron_events_prt.htm&quot; rel=&quot;noreferrer&quot;&gt;noise level can be reduced&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the nacelle the engine would create much less thrust and more drag, and bigger, more powerful engines would be needed. Bigger engines would create more noise, too, so this is also an indirect way how nacelles help to keep noise down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A last noise reduction contribution to mention here is the capacity of the nacelle to contain the shrapnel from a failed fan blade. Fan blade failure is all but silent, but if the blade fragments would escape at high speed, the noise of what follows next would also be considerable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-10-23T13:28:55.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11893" PostTypeId="1" AcceptedAnswerId="11897" CreationDate="2015-01-22T08:21:34.177" Score="9" ViewCount="5756" Body="&lt;p&gt;This arose out of a comments discussion in &lt;a href=&quot;https://aviation.stackexchange.com/questions/11871/who-decides-how-fast-commercial-aircraft-fly-the-pilots-or-atc&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only airspace I really know is the UK.  Here, a controller may issue a clearance to exceed the 250kt limit below 10,000ft for reasons other than minimum safe flying speed, e.g. to expedite a transition for spacing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this common, e.g. in the US?  I know it's open ended but I'm interested in whether this is just some &quot;local&quot; thing.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-01-23T20:00:35.927" Title="How or when can the 250 KIAS speed limit below 10,000ft be exceeded?" Tags="&lt;air-traffic-control&gt;&lt;regulations&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11894" PostTypeId="2" ParentId="11890" CreationDate="2015-01-22T08:21:45.317" Score="7" Body="&lt;p&gt;In order to engage the usual arresting gear (cables) on an aircraft carrier, &#xA;it helps to have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Tailhook&quot; rel=&quot;nofollow&quot;&gt;tail hook&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other forms of &lt;a href=&quot;http://en.wikipedia.org/wiki/Arresting_gear&quot; rel=&quot;nofollow&quot;&gt;arresting gear&lt;/a&gt; that do not require a tail hook.&#xA;Presumably the main limitations on an aircraft using them are the size, weight,&#xA;and landing speed of the aircraft.&#xA;These devices do not seem to be designed for as frequent use as &#xA;the arresting cables of a carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Followup:&lt;/strong&gt; As I found out on looking into this further, &#xA;many (most? all?) present-day land-based fighter jets, &#xA;not just Navy or Marines jets, have tail hooks as well. &#xA;However, at least according to &lt;a href=&quot;http://flyingwithfish.boardingarea.com/2012/12/26/reader-mail-why-do-air-force-jets-have-tailhooks/&quot; rel=&quot;nofollow&quot;&gt;this blog entry&lt;/a&gt;,&#xA;tail hooks of the types of aircraft used by the US Air Force (and some other&#xA;air forces) are not designed to work with aircraft carrier arresting cables&#xA;but only with land-based systems (which suspend the cables higher than the &#xA;aircraft carrier systems do).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in a comment (and in the Wikipedia article on &quot;Arresting gear&quot; linked above), barrier nets can serve as arresting gear.&#xA;Various publications (for example the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/artcc/anchorage/media/AK_Sup.pdf&quot; rel=&quot;nofollow&quot;&gt;Supplement Alaska&lt;/a&gt;, pp. 10&amp;ndash;11,&#xA;accessed 22-Jan-2015)&#xA;list numerous kinds of gear, including cables designed to engage tail hooks, woven straps designed to be torn by tail hooks (one-time use only!), nets designed to engage struts, nets designed to engage wings, nets combined with cables, and engineered material arresting systems (EMAS) that absorb energy as they are crushed under the wheels of the aircraft. I have not yet found any citations of EMAS being used by military aircraft, but its main limitation of seems to be landing speed rather than aircraft weight or size, as &lt;a href=&quot;https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=13754&quot; rel=&quot;nofollow&quot;&gt;an FAA fact sheet on EMAS&lt;/a&gt; dated December 12, 2014 credits these systems with stopping nine aircraft that overran runways in separate incidents, including a Boeing 747, an MD-11, and an Airbus A320.&lt;/p&gt;&#xA;" OwnerUserId="3831" LastEditorUserId="3831" LastEditDate="2015-01-23T13:00:06.213" LastActivityDate="2015-01-23T13:00:06.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11897" PostTypeId="2" ParentId="11893" CreationDate="2015-01-22T09:41:12.253" Score="13" Body="&lt;p&gt;Not a local thing at all!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Australia, it is extremely common to hear, especially for aircraft on departure. Listening to LiveATC, particularly Sydney International Approach/Departure (YSSY) you will quite often hear ATC give an aircraft permission to exceed 250KIAS below 10,000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Qantas 123:&#xA;Approach, QFA123, with you passing 2,300, climbing 5,000..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sydney Approach:&#xA;QFA123, Identified, Climb FL240, cancel speed restrictions below 10,000..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of reasons this is used. The first, I have already hinted to in the example radio call above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Departures:&#xA;It is extremely common to hear ATC cancel speed restrictions on departing aircraft. This gives better separation for aircraft departing in the same direction. For example, one of the busiest sectors in the world is Sydney - Melbourne Australia. The common SID's out of Sydney for Melbourne are the DEENA4 WOL transition and the WOL1 Departure, depending on operational runway. As a large amount of aircraft use these departures, the further the lead aircraft can get on the SID prior to the trailing aircraft becoming airborne, the better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arrivals:&#xA;Again, using Sydney, they receive a large amount of Regional Turbo-Prop traffic (Dash 8-Q300/Q400, Saab 340B, BE350). You will commonly hear Approach cancel speed restrictions on these aircraft on decent so they can give them more space on the approach. They land reasonably slower than a B747/A380, so the more room, the better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is simple. These guys are operating commercial operations, hence faster is better, especially on descent. So if there is no or low traffic in the TMA, ATC will commonly release the speed restriction on aircraft to accommodate the company operations.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastEditorUserId="3504" LastEditDate="2015-01-22T14:48:31.717" LastActivityDate="2015-01-22T14:48:31.717" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11899" PostTypeId="1" CreationDate="2015-01-22T10:06:03.323" Score="2" ViewCount="561" Body="&lt;p&gt;What kind of extreme weather would justify a pilot of a commercial airliner taking avoidance measures to the point of likely stall?&lt;/p&gt;&#xA;" OwnerUserId="6938" LastEditorUserId="1696" LastEditDate="2015-02-05T16:53:07.723" LastActivityDate="2015-02-05T16:53:07.723" Title="What extreme measures might a pilot take to avoid extreme weather?" Tags="&lt;weather&gt;&lt;stall&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11900" PostTypeId="1" CreationDate="2015-01-22T10:11:52.580" Score="0" ViewCount="65" Body="&lt;p&gt;Why is it possible for pilots of commercial airliners to execute manoeuvres virtually guaranteed to cause a stall?&lt;/p&gt;&#xA;" OwnerUserId="6938" LastActivityDate="2015-01-22T10:22:01.657" Title="Safety measures to prevent pilots causing passenger planes to stall" Tags="&lt;stall&gt;" AnswerCount="0" CommentCount="0" FavoriteCount="0" ClosedDate="2015-01-22T13:15:19.117" ContentLicense="CC BY-SA 3.0" />
  <row Id="11901" PostTypeId="1" CreationDate="2015-01-22T10:17:01.517" Score="11" ViewCount="2123" Body="&lt;p&gt;What measures are in place to prevent pilots from being put in charge of passenger planes without an appropriate level of training and skill? Are these measures enforced equally by different countries, airlines and aviation authorities?&lt;/p&gt;&#xA;" OwnerUserId="6938" LastEditorUserId="572" LastEditDate="2015-02-24T10:40:40.940" LastActivityDate="2015-02-24T10:40:40.940" Title="How do airlines make sure that pilots remain skilled enough to operate aircraft? What quality assurance is there for certified pilots?" Tags="&lt;flight-training&gt;&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11902" PostTypeId="2" ParentId="11827" CreationDate="2015-01-22T10:22:01.657" Score="4" Body="&lt;p&gt;A couple of reasons, but essentially it comes down to &quot;Because sometimes it may be the lesser of two evils&quot;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Instruments go wrong. Pitot tubes break, gyroscopes go wonky etc... Sometimes, the pilot really does know best. Autopilots disengage when they aren't sure what to do, the same applies to autopilots limiting the control in a fly by wire setup... what happens when the aircraft thinks it's stalling but it isn't? It tries to prevent the nose being raised, or actually lowers the nose, until the aircraft hits the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A &quot;virtually guaranteed stall&quot; may one day be a better option than an &quot;actually  guaranteed collision&quot; - if your choices are pull up hard or fly into a mountain, I'll take my chances with attempting to recover from a stall.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;1 is unlikely (and considering how often aircraft fly under IFR, would likely affect the pilot the same as the autopilot), 2 is probably even more unlikely, but is the situation which would prompt thousands of &quot;Why can't the pilot over-ride the autopilot?&quot; questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the end of the day, people still mistrust computers. They may get it right 99.9999% of the time, but they still can't &quot;think on their feet&quot; like a human.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, there are elements of this already in aircraft design. For example all modern airliners have audible/visual warnings when dangerous situations are presented (high sink rates, stall warnings etc). And Airbus goes further, using &quot;fly by wire&quot; controls which do indeed prevent most &quot;normal&quot; stall situations in what's called &quot;Normal law&quot;. Airbus does, however, give final control to the pilot if the computer is not 100% sure of the situation.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-22T10:22:01.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11903" PostTypeId="2" ParentId="11899" CreationDate="2015-01-22T10:27:37.387" Score="6" Body="&lt;p&gt;Any which the pilot thinks is more dangerous than the avoidance measures?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were driving at 100mph towards a wall which you reckoned had a 90% chance of a head-on collision, or could attempt to turn which had a 50% chance of throwing you off a cliff, which would you choose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any decision the pilot makes will be made on the basis of &quot;Taking this action is a better option than not taking it&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main weather which would likely cause this would be high enough levels of icing to be dangerous, or such severe turbulence that the pilot believes the plane will be &quot;upset&quot; enough to throw it out of the performance envelope. A combination of these may be present in a severe storm.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-22T10:27:37.387" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11904" PostTypeId="2" ParentId="11901" CreationDate="2015-01-22T10:35:04.893" Score="19" Body="&lt;p&gt;Put quite simply for this answer - The Licence a pilot holds is the assurance that the pilot has received the appropriate level of training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each country has it's own standards for training, their own requirements, and their own limitations on the operation of that licence. In saying that, MOST countries standards are reasonably in-line in regards to Aeronautical Experience required to sit each flight test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Australia, the requirement to sit a Commercial Pilot Licence is a minimum of 200 hours Aeronautical Experience (150 hours if ALL training has been conducted on an Integrated Course, now to be recognized under Part 141). From there, there is a break down of what that 200/150 hours must consist of. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, having a Commercial Pilot Licence (again, speaking from an Australian point of view) does not give a pilot the right to sit in the left seat of an Airliner. You need further training such as;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Multi-Engine Command Instrument Rating&lt;/li&gt;&#xA;&lt;li&gt;Type Endorsement (for the intended aircraft)&lt;/li&gt;&#xA;&lt;li&gt;Crew Resource Management Training&lt;/li&gt;&#xA;&lt;li&gt;Dangerous Goods Training&lt;/li&gt;&#xA;&lt;li&gt;Senior First Aid (Not mandatory, but common)&lt;/li&gt;&#xA;&lt;li&gt;Company, Emergency, Cyclic and Systems checks (per company)&lt;/li&gt;&#xA;&lt;li&gt;Air Transport Pilot Licence Theory Exams (in some cases, Airlines may not even look at you if you haven't completed these - In&#xA;Australia, it is an unwritten must-have!)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And thats just to sit in as a Co-Pilot.. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Captains need years of experience, and a lot more training and check to get into that coveted Left Seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So again, to bluntly answer your question, regardless of country, there is law in place that stipulates that Pilots must be appropriately trained to fly airliners.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2015-01-22T10:35:04.893" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11905" PostTypeId="2" ParentId="11901" CreationDate="2015-01-22T10:56:11.307" Score="1" Body="&lt;p&gt;That is the function of a license. Every country has their own standards, and by international treaties most countries must respect the licenses issued by other countries. So, for example, a Malaysian pilot is allowed to fly in the United States, even though he has a Malaysian license and does not have an FAA license. For this reason, it may be slightly more dangerous to fly on foreign air carriers, especially if they are from sketchy, third-world countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carriers have much different standards for who is allowed to captain an aircraft. For example, a big carrier like Delta will usuallly have tougher standards than a regional airline or a charter company, but not necessarily. You can find small charter companies with really tough standards, and others that will let much less experienced captains fly their aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not think that safety is purely a product of training and experience. You can find guys with 10,000 hours who do stupid stuff and make bumpy landings all the time and kids with 800 hours who fly ten times better than them. Skill does not necessarily = experience. Also, performance in a crisis has little to do with experience. Put one guy in a crisis and he might freeze up like a rabbit, and another cooly reacts with correct decisions. It's impossible to predict ahead of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In difficult situations often judgement is more important than skill or experience, although experience can help improve judgement. Examiners will try to test a pilot's judgement, but it is hard to do. It's an undefinable quantity. Once again, you can have a guy with 800 hours who has much better judgement than the long-timer Navy pilot with 10,000 hours. It's difficult to predict.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-22T10:56:11.307" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="11906" PostTypeId="1" AcceptedAnswerId="12340" CreationDate="2015-01-22T11:50:43.763" Score="4" ViewCount="4010" Body="&lt;p&gt;I am just in the process of doing a bit of study in the hope of doing my Basic Gas Turbine Endorsement in the next few months, and just wanted some feedback/comments/discussion on the major hazards associated with starting, managing and shutting down a PT6 Turbine Engine (PT6 as it is the most common used Turbine Engine on an aircraft I will touch for this endorsement).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mainly, what I am looking at is during the start - If the EGT raises above the evil 700* mark, what is the best course of action to prevent &quot;melting the turbine&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During Climb/Cruise Operation - What are the most common failures, and their indications?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintenance/Shutdown - What are the most common methods of recording Cycles? By landing or by Start/Shutdowns?&lt;/p&gt;&#xA;" OwnerUserId="3223" LastEditorUserId="65" LastEditDate="2015-01-22T16:23:09.153" LastActivityDate="2015-06-17T21:54:58.647" Title="What are the major hazards in operating a PT6 Turbine Engine?" Tags="&lt;aircraft-performance&gt;&lt;turboprop&gt;&lt;turbine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11907" PostTypeId="2" ParentId="11893" CreationDate="2015-01-22T13:02:48.107" Score="4" Body="&lt;p&gt;In the US, speed restrictions are frequently cancelled, either to ensure or to increase separation between aircraft, as per &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;ATC Handbook 4/3/14 JO 7110.65V, Section 5-7. Speed Adjustment&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5−7−1. APPLICATION Keep speed adjustments to the minimum necessary to&#xA;  achieve or maintain required or desired spacing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-22T16:06:52.003" LastActivityDate="2015-01-22T16:06:52.003" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11908" PostTypeId="2" ParentId="11899" CreationDate="2015-01-22T14:18:41.310" Score="2" Body="&lt;p&gt;Realistically I can only think of one: downburst on final approach. In downburst the aircraft in relatively quick succession encounters headwind, downwind and tailwind. The increase of headwind causes increase in airspeed, but loss of kinetic energy due to increased drag. Then the downwind simply causes loss of altitude and finally the change from headwind to tailwind causes loss of airspeed that may be easily large enough to stall the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this dangerous phenomenon is encountered at low altitude (it only occurs at low altitude, too), the pilot must fly the aircraft at the edge of stall to preserve as much height as possible and hope the engines will be able to make up for the lost energy before he runs out of it. It is the reason Airbus introduced alpha-limit on A320 and alpha-protection already earlier. Alpha-limit limits angle of attack to just below stall when the side-stick is moved all the way aft and alpha-protection sets full power when a slightly lower angle of attack threshold is exceeded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose this is not what you meant. No, I can't think about anything at high altitude that would call for such aggressive manoeuvre. At altitude either you see the weather developing ahead for couple of minutes (with eyes or on weather radar) and avoid it using normal manoeuvres or you hit unexpected clear air turbulence and just react to it. And clear air turbulence is quite likely to make the plane loose altitude, hundreds of feet, rarely even couple thousand feet, but not gain it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-01-26T13:47:56.860" LastActivityDate="2015-01-26T13:47:56.860" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11909" PostTypeId="1" CreationDate="2015-01-22T14:28:22.437" Score="5" ViewCount="774" Body="&lt;p&gt;After reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/11893/exceeding-the-250kt-speed-limit-below-10-000ft&quot;&gt;this question&lt;/a&gt; about being cleared to go faster than 250kts in airspace that otherwise has a speed limit, I began to wonder how far can Air Traffic Controllers (ATCs) can bend the rules on an aircraft-to-aircraft basis?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a limit to what exceptions ATC can make for someone?  I'm particularly interested for the answer in the USA, but I'm sure information about other countries would also be enlightening.  &lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2021-02-10T03:31:18.283" Title="How much &quot;power&quot; do ATCs really have?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;regulations&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11911" PostTypeId="1" AcceptedAnswerId="11935" CreationDate="2015-01-22T15:24:13.213" Score="9" ViewCount="1202" Body="&lt;p&gt;The rover - without wings - has around 1000 kg of mass and Mars has 38% of Earths g. The density of the atmosphere is 1% of that of Earth. Assuming the surface area of the wings could be used for photoelectric cells having an efficiency of 40% at 500W/m^2, what wing dimensions, power and speed would this airborne rover need? &lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-01-25T20:34:54.543" Title="What kind of wing-surface area would Curiosity need to be able to fly in the atmosphere of Mars?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11912" PostTypeId="2" ParentId="11909" CreationDate="2015-01-22T15:28:05.480" Score="5" Body="&lt;p&gt;As far as I know, most regs have some sort of out that says &quot;unless directed by ATC,&quot; and ATC has two unbreakable rules which limit much of what they are allowed to do:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;thou shall not vector airplanes into obstacles, terrain, unflyable weather or atmospheric conditions, restricted (in the lay sense of the term) airspace, or other aircraft&lt;/li&gt;&#xA;&lt;li&gt;thou shall not deviate from aircraft separation&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Other than that, when it comes to clearances, ATC has a fair amount of latitude to give you what they want, or what you ask for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The balance of responsbility between ATC and the pilot in command, is covered by &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/91.123&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.123&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.123 Compliance with ATC clearances and instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) When an ATC clearance has been obtained, &lt;strong&gt;no pilot in command may&#xA;  deviate from that clearance unless an amended clearance is obtained,&#xA;  an emergency exists, or the deviation is in response to a traffic&#xA;  alert and collision avoidance system resolution advisory&lt;/strong&gt;. However,&#xA;  except in Class A airspace, a pilot may cancel an IFR flight plan if&#xA;  the operation is being conducted in VFR weather conditions. When a&#xA;  pilot is uncertain of an ATC clearance, that pilot shall immediately&#xA;  request clarification from ATC.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Except in an emergency, no person may operate an aircraft contrary&#xA;  to an ATC instruction in an area in which air traffic control is&#xA;  exercised.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each pilot in command who, in an emergency, or in response to a&#xA;  traffic alert and collision avoidance system resolution advisory,&#xA;  deviates from an ATC clearance or instruction shall notify ATC of that&#xA;  deviation as soon as possible.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Each pilot in command who (though not deviating from a rule of&#xA;  this subpart) is given priority by ATC in an emergency, shall submit a&#xA;  detailed report of that emergency within 48 hours to the manager of&#xA;  that ATC facility, if requested by ATC.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Unless otherwise authorized by ATC, no person operating an&#xA;  aircraft may operate that aircraft according to any clearance or&#xA;  instruction that has been issued to the pilot of another aircraft for&#xA;  radar air traffic control purposes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-22T22:19:06.870" LastActivityDate="2015-01-22T22:19:06.870" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11913" PostTypeId="2" ParentId="11887" CreationDate="2015-01-22T15:43:14.843" Score="7" Body="&lt;p&gt;Not according to the authors of &lt;a href=&quot;http://rajsisodia.com/raj/wp-content/uploads/2012/07/4As-of-Marketing-Introduction-and-Chapter-1.pdf&quot;&gt;The 4 A's of Marketing&lt;/a&gt; &lt;sup&gt;&lt;a href=&quot;https://books.google.co.uk/books?id=sxKpAgAAQBAJ&amp;amp;pg=PA16&quot;&gt;1&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Despite impressive technological achievements and great expectations all around, the service’s business performance ultimately proved an &lt;strong&gt;abject failure&lt;/strong&gt;. In the ten years before Verizon finally pulled the plug, Airfone generated only 50 million total calls, a fraction of the calls carried daily by cellular companies. While the Airfone service was heavily used when bad weather caused significant delays, the system’s utilization at other times was extremely low. A typical plane was equipped with as many as 60 phones. From these, the average large jet generated fewer than 100 calls per day in about 16 hours of flying time. As a result, &lt;strong&gt;the expensive system, with its heavy load of fixed costs, remained idle well over 99% of the time.&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;While Airfone claimed that some customers’ monthly bills topped out&#xA;  at $4,000, there were not nearly enough of them to sustain the service’s sky-high fixed&#xA;  costs. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Within a few years of the service’s launch, airlines started to remove the expensive phone&#xA;  infrastructure from their cabins, since &lt;strong&gt;the Airfone cost them more in increased fuel&#xA;  consumption (because of the system’s weight) than it generated revenues&lt;/strong&gt; through their&#xA;  revenue sharing arrangement with Verizon. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My emphasis.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-01-22T15:52:07.573" LastActivityDate="2015-01-22T15:52:07.573" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11914" PostTypeId="2" ParentId="11899" CreationDate="2015-01-22T17:20:31.037" Score="3" Body="&lt;p&gt;If you are talking about the &lt;a href=&quot;http://www.cnn.com/2015/01/20/asia/airasia-disaster-flight-speed/&quot; rel=&quot;nofollow&quot;&gt;AirAsia Crash&lt;/a&gt;, you may have some misapprehensions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, the problem with a storm is not &quot;avoidance&quot; once you are in it. The problem is keeping the aircraft flying in a stable configuration in the presence of violent winds. A powerful enough wind can literally turn a small aircraft upside down and backwards. Big Jets are much less susceptible, but can still be thrashed around violently in a storm. The pilot has to react to these upsets and keep flying. So, for example, if the winds put you into a stall, you have to recognize that and do what is necessary to keep air moving over the wings properly. Sometimes, the necessary actions might be completely unintuitive or different than what is normal. For example, if you are upside down, some of the controls work in reverse. If you do not know that, or are not practiced in flying upside down, then making that adjustment can be difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A big problem in such circumstances is that in a storm you may not be able to see the horizon, so you have no visual reference for horizontal stability. Moreover, the artificial horizon, the instrument that tells you your attitude, has a lag, so what you are seeing on the instrument was the situation 1 or 2 seconds ago, whereas your current situation may have changed. In a spin or other rapidly changing flight condition the artificial horizon will be wobbling wildly and unpredictably and is less useful than normal in determining what the true attitude of the aircraft is. In a non-visible conditions this can lead to disorientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the AirAsia flight, the storm could have been putting them into a stall and the aircrew's reactions were not vigorous enough to correct it. Unless details are released on their control inputs and other data, we have no way of knowing. Also, they may have just taken the wrong actions. For example, if you are in normal stall you push the stick forwards to get the nose down, but if you are nose up and upside down, then you have to pull the stick &lt;em&gt;backwards&lt;/em&gt; to get the nose down. Since you cannot see, it can be difficult to tell if you are upside down or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, sometimes a pilot will panic if they are losing altitude fast and pull back on the stick, a fatal reaction. Being inside a storm can be very frightening, even to pilots experienced with flying in them (such as meterological pilots), so panic is a real possibility. Once a person becomes panicked, their training goes right out the window and they can do very illogical things. I was once in aircraft with a high-hour CFI who panicked and he did some crazy things.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-22T17:20:31.037" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11915" PostTypeId="2" ParentId="11909" CreationDate="2015-01-22T17:44:35.317" Score="0" Body="&lt;p&gt;The speed limit of 250kts below 10,000 feet is mostly there to protect smaller aircraft and rotocraft.&lt;br&gt;&#xA;For example, you might have a parachute jump plane flying around, and you don't want a Citation business jet bearing down on them (or the jumpers) at 400 knots: At that speed you don't have much time to react: You look away for two seconds to drink your coffee and BAM!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a famous accident a couple of years ago in which a glider pilot was flying around Reno and a private jet flew right into him (&lt;a href=&quot;http://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief.aspx?ev_id=20060906X01297&amp;amp;key=2&quot; rel=&quot;nofollow&quot;&gt;NTSB file LAX06FA277B&lt;/a&gt;) . That is exactly the kind of accident speed limits are supposed to mitigate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot exceeds a speed limit, it really doesn't matter what ATC said, it is the pilot who is responsible. If the FAA determines he did something reckless it makes no difference that some controller told him it was ok.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="64" LastEditDate="2015-01-22T20:47:25.370" LastActivityDate="2015-01-22T20:47:25.370" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11916" PostTypeId="1" AcceptedAnswerId="11919" CreationDate="2015-01-22T18:07:32.640" Score="4" ViewCount="1249" Body="&lt;p&gt;I know that 757, 737 generate strong Wake Turbulence and as pilots, we should always be aware of that and caution for the wake turbulence while landing and departing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to know if is there like a list of commercial aircraft based on their Wake turbulence generation?  Which one generate the most and which one generate the least? Let's assume they are all heavy, clean, slow!   &lt;/p&gt;&#xA;" OwnerUserId="3455" LastActivityDate="2015-01-22T22:56:18.947" Title="What type of commercial aircrafts generate strong Wake Turbulence?" Tags="&lt;wake-turbulence&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11917" PostTypeId="1" CreationDate="2015-01-22T18:29:35.377" Score="15" ViewCount="6139" Body="&lt;p&gt;In the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11787/is-there-any-disadvantage-to-having-the-de-icing-system-on&quot;&gt;this question&lt;/a&gt;, it is said that &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The de-icing system on most turbine aircraft (including MD-82 involved in that accident) uses bleed air from the engines, that is it extracts some air from behind the (low pressure stage of the) compressor. This air is therefore not ejected from the nozzle and not producing thrust, so the thrust is reduced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My question is: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why is bleed air taken from some stage of the compressor used? Why not e.g. exhaust gas?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For de-icing, the temperature of the used medium must be above 0°C (melting ice), while the environmental temperature usually is far below. &#xA;So the engine has to invest energy to generate bleed air with reasonable temperature, the air cools down to still &gt;0°C during de-icing, and is then vented out to the environment. &#xA;There, it expands and cools down far below the environmental temperature.&#xA;This expansion means that energy is wasted, and also, when the bleed air is cooled down / expanded before inserting it into the de-icing system (I don't know if this is done), energy would be lost.&#xA;In addition, air/pressure is lost in the compressor stage, which makes the combustion less effective. (Again, I don't know how much air is taken, and how big the effect is)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other side, the exhaust gas of the engine is very hot due the combustion and could be used without the need of extra compression. So, using some exhaust gas, one would not waste so much energy. If it's too dirty, heat exchangers could be used to heat fresh air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think of this reasons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Bleed air is anyway used for many purposes in an aircraft, so this is more economic than a completely separated system&lt;/li&gt;&#xA;&lt;li&gt;De-icing is not used for long time during flight, so again no need for a dedicated system&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to expand the question to explain what makes me curious. In the comment, the correctness of this sentence is challenged:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There, it expands and cools down far below the environmental temperature.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is a simple thermodynamic process. The air is compressed adiabatically, i.e. without adding heat to it. The heat comes from the thermal energy of the air, now also compressed to a lower volume.&#xA;De-icing cools down the air, and when releasing the air to the environment, it expands to the orignal pressure. As thermal energy has been removed during de-icing, the temperature drops below environmental temperature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the math behind:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The relation of pressure and temperature in this case is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ p_1^{1-\gamma}\cdot T_1^\gamma=p_2^{1-\gamma}\cdot T_2^\gamma\qquad \gamma&#xA;\approx 1.4$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume a pilot switches on de-icing during flight at 11km altitude. There, environmental pressure is 0.25bar (atmospheres) and temperature is -50°C (223K). It was also said here in the answers that it's possible that the bleed air has about 200°C (473K).&#xA;The formula now gives a bleed air pressure of 3.47 bar, so a pressure ratio of about 14. The air is now cooled down while the pressure is maintained by the engine. I assume de-icing will be effective for bleed air temperatures above 0°C. So if the air is released at this temperature, the temperature will fall down to -144°C (128K). Another number: If releasing at 100°C, the temperature will drop to -97°C (175K). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Of course, the air will mix with the environmental air immediately)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In principle, one can play with the numbers, increase/decrease altitude / temperatures and discuss how adiabatically this (de)compression processes are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, this is a big air conditioner, using the thermal energy for de-icing and wasting the cooled air. If one only needs hot air, something coming from the exhaust system would always be more efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not really efficient. May be the bleed air behind the de-icing system can still be used for other purposes, as it still has the pressure?&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-01-23T16:22:38.773" Title="Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?" Tags="&lt;anti-ice&gt;&lt;bleed-air&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11918" PostTypeId="1" AcceptedAnswerId="11922" CreationDate="2015-01-22T18:35:04.637" Score="13" ViewCount="841" Body="&lt;p&gt;With commercial aircraft flying slightly above Mach 0.8, is there any surface exposed to speed of air significantly larger, e.g. near Mach 1? ignoring:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engine components,&lt;/li&gt;&#xA;&lt;li&gt;The boundary layer as clarified by &lt;code&gt;Trebia Project&lt;/code&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: Reading useful information provided in comments and answers, I realize the key notion is &quot;critical Mach number&quot;, and the question boils down to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are commercial jets flying at critical Mach number speed or higher?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;since the critical Mach number speed is -- by definition -- the one at which some airfoil portion experiments a supersonic airflow. See also:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1413/how-does-exceeding-the-critical-mach-number-of-an-aircraft-affect-its-operation&quot;&gt;How does exceeding the critical Mach number of an aircraft affect its operation?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-09-28T01:51:06.053" Title="Is there a surface of a commercial jet exposed to air flow at speed near Mach 1?" Tags="&lt;aircraft-performance&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="11919" PostTypeId="2" ParentId="11916" CreationDate="2015-01-22T18:38:13.977" Score="9" Body="&lt;p&gt;Big ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wake turbulence is primarily proportional to the aircraft's weight, since this is generally directly related to the size of the aircraft and the amount of air the wings need to move to provide enough lift. Aircraft are categorized with respect to wake turbulence based on their maximum certificated takeoff weights. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-23G.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AC 90-23G&lt;/a&gt; describes classes for ATC purposes as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Super - Interim class for the A380 and AN225&lt;/li&gt;&#xA;&lt;li&gt;Heavy - 300,000 lb or greater&lt;/li&gt;&#xA;&lt;li&gt;Large - 41,000 - 300,000 lb&lt;/li&gt;&#xA;&lt;li&gt;Small - 41,000 lb or less&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Heavy and Super category aircraft are required to add their category to their callsign when contacting ATC, e.g., &quot;Speedbird 12 Super&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft in higher categories have larger separation requirements when in front on aircraft in smaller categories, such as between takeoffs or landings, and ATC will issue &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;caution messages cautionary advisories when required (Section 2-1-20)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AC linked above discusses further on wake turbulence, such as how it propagates and how it should be avoided or escaped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA is also working on a &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2012/SAFO12007.pdf&quot; rel=&quot;noreferrer&quot;&gt;6 category system (A to F)&lt;/a&gt;, which is in effect at MEM, SDF, CVG, and ATL. &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2014/SAFO14007.pdf&quot; rel=&quot;noreferrer&quot;&gt;There are plans to expand this&lt;/a&gt; to the Metroplexes of Houston, New York, Charlotte, Chicago, and Northern California in 2015.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This approval was based on years of joint research and development by&#xA;  the FAA, Eurocontrol, scientific experts in wake, and experts in&#xA;  safety and risk analysis. Categories are now based on weight,&#xA;  certificated approach speeds, wing characteristics, along with special&#xA;  consideration given to aircraft with limited ability to counteract&#xA;  adverse rolls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-22T22:56:18.947" LastActivityDate="2015-01-22T22:56:18.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11920" PostTypeId="2" ParentId="11917" CreationDate="2015-01-22T18:47:22.990" Score="7" Body="&lt;p&gt;Your first reason is the major one: &lt;a href=&quot;http://en.wikipedia.org/wiki/Bleed_air&quot;&gt;Bleed air&lt;/a&gt; is abundant (jet engines generate far more than they &quot;need&quot; for operation), already hot (typically well over 100C), and produced at a relatively high pressure - that's why it's tapped for things like anti-icing systems, cabin air conditioning, and starting other engines.&lt;br&gt;&#xA;It takes little effort in design to install another valve in the bleed air system to direct the flow to anti-icing systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Capturing the turbine exhaust (hot combustion gasses) would require its own special hardware (valves, ducts, etc.), and measures to cool the combustion gasses to a temperature the anti-ice system can handle (heat exchangers), which means more complexity and more weight, so if an aircraft already has a bleed-air system available it makes sense to use it for the de-ice/anti-ice system rather than add another equally-complex arrangement to capture combustion gasses.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For &quot;bleedless&quot; aircraft (ones that don't have the ability to pull bleed air from the engine's compressor) alternate de-icing systems are used (e.g. the 787 uses electric heating elements).&lt;br&gt;&#xA;These could also be used on aircraft with bleed systems, but they have their own disadvantages in terms of maintenance, weight, and complexity. (Bleed air anti-icing systems are comparatively simple: a few valves and tubes with holes drilled in them to let the hot air out where it's needed. Maintenance and upkeep are fairly trivial.) &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-22T18:47:22.990" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11921" PostTypeId="2" ParentId="11917" CreationDate="2015-01-22T18:57:05.237" Score="15" Body="&lt;p&gt;Using air from the exhaust section either for anti-ice directly, or using a heat exchanger, would create many problems.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The air must first be used to burn fuel before reaching a turbine bleed location. Air taken from the compressor section hasn't required any fuel to be burned (other than to compress that air of course).&lt;/li&gt;&#xA;&lt;li&gt;The air will be much, much hotter than air from the compressor. Turbines, especially in the high pressure section, are made of specialized alloys and can be additionally actively cooled to prevent them from melting. This means more specialized, and therefore more expensive and/or heavy material must be used for the whole anti-ice system.&lt;/li&gt;&#xA;&lt;li&gt;Components must also be designed for the case of this bleed air leaking. Hotter turbine air would be a huge problem for this.&lt;/li&gt;&#xA;&lt;li&gt;The air will have the combustion byproducts in it. This can coat the insides of the anti-ice system, reducing its effectiveness, and possibly requiring it to be disassembled and cleaned periodically.&lt;/li&gt;&#xA;&lt;li&gt;If there is some type of engine fire, the fire typically goes downstream, which would send it into this anti-ice system as well.&lt;/li&gt;&#xA;&lt;li&gt;In the case of using a heat exchanger, this would be yet another component to fit into spaces that are already very full, and yet more weight on the airplane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The air from the compressor is already plenty hot. Take a look at &lt;a href=&quot;https://aviation.stackexchange.com/a/8536/1696&quot;&gt;the diagram in this answer&lt;/a&gt;. Notice that all the compressor bleed air goes through the precooler &lt;em&gt;before&lt;/em&gt; going to cowl or wing anti-ice. This means that &lt;strong&gt;the compressor air is already &lt;a href=&quot;https://aviation.stackexchange.com/questions/5031/how-hot-would-pressurized-air-get-if-the-air-conditioning-failed&quot;&gt;hotter&lt;/a&gt; than is required.&lt;/strong&gt; So taking air from the turbine provides no benefit for creating the problems listed above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, taking air from the compressor &lt;a href=&quot;https://aviation.stackexchange.com/questions/8408/why-do-pilots-disable-the-air-conditioning-packs-during-takeoff&quot;&gt;does reduce engine efficiency&lt;/a&gt;, but you are going to have to get that energy from somewhere.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To address your points about the thermodynamics:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming your numbers are correct, what is wrong with that scenario? Releasing air at -97°C that was initially at -50°C means that you extracted 47°C of energy from it to use for anti-ice, using the systems already available on the aircraft (bleed air, precooler). Kind of like a heat pump, but just using air? Wouldn't it be less efficient to burn fuel to heat this air, which would then leave the aircraft at a higher temperature, and therefore throwing away more energy?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In principle, one can play with the numbers, increase/decrease altitude/temperatures and &lt;em&gt;discuss how adiabatically this (de)compression processes are&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis added) I'm not convinced that your assumption that these processes are adiabatic is a good basis for your model, since that is an idealization (though your initial bleed numbers do seem to match &lt;a href=&quot;http://www.skybrary.aero/index.php/Bleed_Air_Systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/88218main_H-1679.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;). An important point is the way the air is used. A typical installation uses piccolo tubes. Small holes along the tubes release the air onto the leading edge. This whole leading edge cavity then vents to the environment. (This doesn't seem to match your assumption that the air is cooled at constant pressure) In order for this air to be useful any further, you would have to somehow return this air to for reuse. This adds more complication, when there is already an abundant supply of compressed bleed air available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option would be to somehow maintain the pressure behind the surfaces with ice protection. This may be feasible for the engine inlet, but not for wing leading edges that include moving slats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even assuming you can somehow recover this air for use, that would be another system and more complication added to the aircraft. And you can't rely on this system, because anti-ice is not always in use. You have to provide a pretty large gain in efficiency to justify adding weight and complexity to the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe you would like to see proof that most the work done on the air is used in the anti-ice process, and adding heat from combustion is not necessary. We may need to get someone like Peter Kämpf in here to run some numbers.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-01-23T16:22:38.773" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11922" PostTypeId="2" ParentId="11918" CreationDate="2015-01-22T20:20:26.147" Score="12" Body="&lt;p&gt;Of course! If you check the &lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_Mach_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia page&lt;/a&gt; the Critical Mach Number of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it.&#xA;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Drag Divergence Mach Number&lt;/a&gt; is usually bigger than the Critical Mach Number, it means that at that speed there are big surfaces exposes to speed of air larger than 1. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can happen because the figure of an airplane is shaped in order to avoid shock waves with flow and to postpone the maximum as possible the Drag divergence Mach number (in order to have a greater cruise speed). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where? &#xA;On the upper part of the wings, where the flow is accelerated in order to produce lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clarification about engines (thanks to the help of one of the comments):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flow from a jet engine has a speed about double of the cruise speed of the airplane. Anyway the outflow from an airliner jet engine is much hotter than the surrounding air, so the speed of sound in this gas stream is much higher; its Mach number is still &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/adjustable-area-jet-engine-nozzles/9666#9666&quot;&gt;subsonic&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-09-28T01:51:06.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11923" PostTypeId="2" ParentId="11893" CreationDate="2015-01-22T21:26:15.103" Score="10" Body="&lt;p&gt;In the US, the 250 kt speed limit is codified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7d3384c2354e7d7f123b8e3018f1b96f&amp;amp;node=se14.2.91_1117&amp;amp;rgn=div8&quot;&gt;14 CFR 91.117&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.117&lt;/strong&gt;   Aircraft speed.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note in section (a) that only the administrator may authorize operations below 10,000 feet MSL at speeds above 250 KIAS.  The only exception to this is part (d) which applies to aircraft that cannot safely operate below this speed.  As far as I know this only applies to specific heavy airplanes.  ATC does not have the authority to issue instructions contrary to regulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically the FAA has experimented with the ability of controllers to cancel the 250 kt speed limit within certain class B airspace, notably in the Houston, TX class B.  That program was discontinued and currently no controller may grant you an exception to the regulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the 200 kt speed limit in class C and D surface areas and any speed restriction published on a chart (departure and arrival procedures) &lt;em&gt;can&lt;/em&gt; be cancelled by ATC.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-01-22T21:26:15.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11924" PostTypeId="1" AcceptedAnswerId="11942" CreationDate="2015-01-22T22:50:37.020" Score="11" ViewCount="5306" Body="&lt;p&gt;How much lag does an Attitude Indicator exhibit when it is working as designed? Other than &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/nav/ifr_instr.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;well-known problems&lt;/a&gt; like tumbling beyond certain limits in pitch and roll, and precession errors from the erecting system, does a gyroscopic AI experience lag that makes it unusable for turbulent or gusty conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, are there any conditions that would cause an AHRS-based AI to exhibit lag or otherwise show an incorrect indication of the horizon relative to the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Inspired by comments on &lt;a href=&quot;https://aviation.stackexchange.com/a/11914/136&quot;&gt;this answer&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-19T08:26:40.877" Title="How much lag does an Attitude Indicator experience?" Tags="&lt;flight-instruments&gt;&lt;aircraft-maintenance&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11925" PostTypeId="2" ParentId="11924" CreationDate="2015-01-22T23:39:37.133" Score="6" Body="&lt;p&gt;Talking about vacuum-driven gyros, which are what I'm mainly familiar with: When everything is working as designed (sufficient air pressure for normal gyro rotor speed, moderate maneuvers) there is some lag.&lt;br /&gt;&#xA;You'll notice it if you're looking for it, but the &amp;quot;1-2 seconds&amp;quot; mentioned in the linked answer seems on the high side (at least based on what I've seen in light aircraft).&lt;/p&gt;&#xA;&lt;p&gt;Vacuum-driven attitude indicators lag because of the way they operate: Basically a set of vanes are always trying to pull the gyro upright relative to gravity, and the inertia in those vanes and the air flow induces a slight lag before the rotor (and visual indicator) moves.&lt;/p&gt;&#xA;&lt;p&gt;That's not the only error in your trusty attitude indicator. Stealing liberally from an old edition of the IFR Handbook for the rest of gory details details:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;…&lt;br /&gt;&#xA;Another group of errors, associated with the design and operating principles of the attitude indicator, are induced during normal operation of the instrument. A skidding turn moves the pendulous vanes from their vertical position, precessing the gyro toward the inside of the turn. After return of the aircraft to straight-and-level, coordinated flight, the miniature aircraft shows a turn in the direction opposite the skid. During a normal turn, movement of the vanes by centrifugal force causes precession of the gyro toward the inside of the turn.&lt;/p&gt;&#xA;&lt;p&gt;Errors in both pitch and bank indications occur during normal coordinated turns. These errors are caused by the movement of the pendulous vanes by centrifugal force, resulting in the precession of the gyro toward the inside of the turn. The error is greatest in a 180° steep turn. If, for example, a 180° steep turn is made to the right and the aircraft is rolled out to straight-and-level flight by visual references, the miniature aircraft will show a slight climb and turn to the left. This precession error, normally 3° to 5°, is quickly corrected by the erecting mechanism. At the end of a 360° turn, the precession induced during the first 180° is cancelled out by precession in the opposite direction during the second 180° of turn. The slight precession errors induced during the roll-out are corrected immediately by pendulous vane action.&lt;/p&gt;&#xA;&lt;p&gt;Acceleration and deceleration also induce precession errors, depending upon the amount and extent of the force applied. During acceleration the horizon bar moves down, indicating a climb. Control applied to correct this indication will result in a pitch attitude lower than the instrument shows. The opposite error results from deceleration. Other errors, such as &amp;quot;transport precession&amp;quot; and &amp;quot;apparent precession,&amp;quot; relate to rotation of the earth and are of importance to pilots and navigators concerned with high speed and long-range flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yUQLB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yUQLB.png&quot; alt=&quot;Gyro vanes&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;A more common cause of a (noticeable) gyro lag is low vacuum, which results in low rotor speed and makes the entire instrument sluggish.&lt;br /&gt;&#xA;High vacuum can cause the opposite effect - excessive rotor speed, and &amp;quot;overshoot&amp;quot; in maneuvers.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;You can find more of the old IFR handbook &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/attitude.htm&quot; rel=&quot;noreferrer&quot;&gt;over on pilotfriend.com&lt;/a&gt;. &amp;quot;IFR Exam-o-Gram #24&amp;quot; &lt;a href=&quot;http://www.birdbird.org/aviation/examogram/&quot; rel=&quot;noreferrer&quot;&gt;available here&lt;/a&gt; is also a good read - both of these are from the days when the FAA expected pilots to cram pretty extensive systems knowledge into their brains.&lt;/p&gt;&#xA;&lt;p&gt;The gyro vanes picture above is out of the Airframe mechanic's handbook - &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23018&quot; rel=&quot;noreferrer&quot;&gt;AC 65-15A&lt;/a&gt; which is actually still current.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-22T23:59:04.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11926" PostTypeId="2" ParentId="11924" CreationDate="2015-01-22T23:43:02.743" Score="2" Body="&lt;p&gt;All traditional instruments have a certain amount of lag. This is one of the factors that complicates flight automation. Certain advanced instruments such as inertial measurement units and ring laser gyroscopes have no lag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find details on the typical lag and other issues with the artificial horizon (&quot;attitude indicator&quot;) in any instrument flying textbook, or web site, &lt;a href=&quot;http://www.allstar.fiu.edu/aero/GSI.htm&quot; rel=&quot;nofollow&quot;&gt;such as this one&lt;/a&gt;. Any prolonged non-level flight will produce an error in the AI, and for this reason IFR holding patterns have a one-minute level flight leg after each minute of turn. This extra travel distance gives the AI the time to return to normal.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-22T23:43:02.743" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11928" PostTypeId="1" CreationDate="2015-01-23T00:07:04.263" Score="6" ViewCount="642" Body="&lt;p&gt;I was wondering if a &lt;a href=&quot;http://en.wikipedia.org/wiki/Vehicular_homicide&quot; rel=&quot;nofollow&quot;&gt;vehicular homicide&lt;/a&gt; charge that was not drug or alcohol related will prevent me from get a pilot's license?&lt;/p&gt;&#xA;" OwnerUserId="6961" LastEditorUserId="65" LastEditDate="2015-01-23T14:43:45.967" LastActivityDate="2016-08-23T15:47:16.170" Title="Can I get a pilot's license following a vehicular homicide charge?" Tags="&lt;flight-training&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11929" PostTypeId="1" AcceptedAnswerId="11933" CreationDate="2015-01-23T00:17:52.990" Score="9" ViewCount="2502" Body="&lt;p&gt;I've never seen lateral CG limits prescribed for aircraft (though I have very imited experience in this realm).  Presumably, aircraft are designed to keep the center of balance as close as possible to center of lift, with any imbalances are far more likely to occur fore to aft than side to side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, for instance, what if fuel only drained from one wing during flight?  How much of an imbalance would this create?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there on-board systems in general aviation to prevent this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the effects of a lateral imbalance on handling, and how could pilots compensate, if possible?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 1: Please do not restrict your answers to fuel loads.  Is there a percentage-based (e.g. greater than X % aircraft total wingspan) or positional-based (e.g. lateral CG moved outside of the fuselage) DNE from an engineering standpoint?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 2: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also seeking design input, considering experimental and purpose-built aircraft such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_White_Knight_Two&quot; rel=&quot;nofollow&quot;&gt;White Knight Two&lt;/a&gt; exist.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also note that despite the larger cargo volume of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;nofollow&quot;&gt;Airbus Beluga&lt;/a&gt;, it cannot carry near as much weight as the smaller-volume &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot; rel=&quot;nofollow&quot;&gt;C-5 Galaxy&lt;/a&gt;.  Is this a benefit of the C-5's design in placing the wings above the fuselage or is there such a thing as vertical CG limits?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="19" LastEditDate="2015-02-18T18:58:29.403" LastActivityDate="2015-02-18T18:58:29.403" Title="What are the limits to lateral Centre of Gravity imbalances?" Tags="&lt;weight-and-balance&gt;&lt;hypotheticals&gt;&lt;cg&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11930" PostTypeId="2" ParentId="11929" CreationDate="2015-01-23T00:22:40.983" Score="3" Body="&lt;p&gt;The weight imbalance is serious. There is even a fuel balance valve in most jets and a warning for fuel imbalance. However, this valve played a significant role in the accident of &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Transat_Flight_236&quot; rel=&quot;nofollow&quot;&gt;Air Transat Flight 236&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As well, in some small passanger aircrafts, you might be weighted prior to boarding and seated so that the plane is balanced.&lt;/p&gt;&#xA;" OwnerUserId="802" LastEditorUserId="802" LastEditDate="2015-01-23T00:30:46.333" LastActivityDate="2015-01-23T00:30:46.333" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11931" PostTypeId="2" ParentId="11929" CreationDate="2015-01-23T01:02:21.017" Score="5" Body="&lt;p&gt;Putting cargo in the right place to maintain lateral CG position is easy, there is little place other than near the center to put it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a different story with the fuel in the wing tanks, a wing with more fuel is heavier and will tend to drop down and requires the pilot to correct for that using the ailerons. This will introduce drag which will increase fuel consumption and lower the speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The limit described in the manual is usually in weight of fuel imbalance. And where the limit is depends from plane to plane and relies on the inherent roll stability and the roll control of the ailerons.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-23T01:02:21.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11932" PostTypeId="2" ParentId="11928" CreationDate="2015-01-23T02:03:36.683" Score="10" Body="&lt;p&gt;I'm assuming you're asking about training in the US because &quot;vehicular homicide&quot; is an American term, at least as far as I know. If that assumption is wrong, please update your question to include the country. You also didn't mention if you were only charged, or actually convicted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, if we assume the US then you need TSA approval before flying solo (for citizens) or before starting flight training (for non-citizens). I have no idea how the TSA would view a vehicular homicide charge (or conviction), but obviously it's a potential issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But assuming you get TSA approval, you'll also need a medical certificate. Criminal charges or convictions shouldn't really matter for that, unless they involve drugs and alcohol (as you mentioned) or if the incident led to you needing long-term drug treatment, a major operation or psychological/psychiatric treatment. The FAA views psychiatric treatment in particular (including most counselling) very negatively, so if you had any that would almost certainly result in a lot of extra paperwork and potentially denial of your application.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, you could go for a &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-Sport-Pilot-Light-Sport-Aircraft-Final-Rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;sport pilot license and fly an LSA&lt;/a&gt; without any medical if you have a valid driver's license. But if the FAA has ever denied a medical application from you, you can't use that option, so research and plan accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if there are no medical issues the only other thing I can think of right now would be insurance. There's no legal requirement in the US to have any insurance in order to fly but most people who rent aircraft (including students) will have renters' insurance in case they damage the aircraft or injure someone or whatever. If your homicide charge resulted in a conviction, that could be a problem for an insurance company. Even if you don't get your own insurance, you might have to sign something for the flight school's insurers stating that you've never been convicted of a felony or motor vehicle charge (I have no idea, by the way, if vehicular homicide is a felony or not). I'm not saying that it would be impossible to get insurance, just that it might come up when/if you apply for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, if you eventually want to get an &lt;a href=&quot;http://en.wikipedia.org/wiki/Airline_Transport_Pilot_Licence&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATP license&lt;/a&gt; then a felony conviction is a potential concern: see &lt;a href=&quot;https://aviation.stackexchange.com/questions/8530/what-does-the-faa-consider-to-be-good-moral-character&quot;&gt;this question&lt;/a&gt; for more information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I'm not a lawyer or a flight instructor so don't take my word on anything important (or unimportant, for that matter). Legal issues are always tricky and for a real answer you should consult an aviation attorney or join &lt;a href=&quot;http://www.aopa.org/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA&lt;/a&gt; and &lt;a href=&quot;http://pilot-protection-services.aopa.org/Attorneys-and-Medical-Experts&quot; rel=&quot;nofollow noreferrer&quot;&gt;ask them&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-08-23T15:47:16.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11933" PostTypeId="2" ParentId="11929" CreationDate="2015-01-23T03:55:51.740" Score="11" Body="&lt;p&gt;Lateral c.g. limits are prescribed for large aircraft both for max fuel imbalance and for what is being carried in the fuselage. It's basically impossible to exceed the max lateral imbalance in a passenger aircraft. Exceeding the max in wide body cargo aircraft can be done and is checked for, but it takes an unusual load to exceed the max.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747-400, for example, has a max lateral imbalance of 10,000,000 inch-pounds. If you load 207,205 lbs on one side only of the main deck of a 747-400 freighter using size code M pallets, you will exceed the maximum. To see this happen (if you're using Firefox or Chrome--IE won't work) go to &lt;a href=&quot;http://747.terryliittschwager.com&quot;&gt;747.terryliittschwager.com&lt;/a&gt;, dismiss the flash screen, and then click on test load #6 near the bottom of the page. That will trigger exceeding the lateral imbalance limit. Scroll down to the Lateral Load Imbalance graphic to see the max lateral loading envelope and the point that shows the load exceeding it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some approximate weights for a 747-400 freighter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;basic operating weight 365,000 lbs&lt;/p&gt;&#xA;&#xA;&lt;p&gt;max fuel 360,000 lbs&lt;/p&gt;&#xA;&#xA;&lt;p&gt;max cargo 245,000 lbs given the 610,000 max zero fuel limitation and a 365,000 bow&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that you cannot carry max fuel and max cargo. A common 747-400 max takeoff weight is 875,000 lbs.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-01-23T04:21:49.117" LastActivityDate="2015-01-23T04:21:49.117" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="11934" PostTypeId="2" ParentId="11929" CreationDate="2015-01-23T05:24:21.513" Score="4" Body="&lt;p&gt;Lateral trim is indeed important. Although there are no &quot;limits&quot; prescribed for most light GA aircraft you can get a feel for how an imbalance can affect flight in some of them.&lt;br&gt;&#xA;This is actually a fun exercise in a Cherokee:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fill one tank to the tab (~16 Gallons, 96 pounds of fuel)&lt;br&gt;&#xA;If you're solo this should be the right tank.&lt;br&gt;&#xA;If you take an instructor the tank on the side of the &lt;em&gt;lighter&lt;/em&gt; person.&lt;/li&gt;&#xA;&lt;li&gt;Fill the other tank completely (~25 gallons, 150 pounds of fuel).&lt;br&gt;&#xA;If you're solo fill the left tank.&lt;br&gt;&#xA;If you take an instructor fill the tank on the side of the &lt;em&gt;heavier&lt;/em&gt; person.&lt;/li&gt;&#xA;&lt;li&gt;Start, run-up, take off, and climb out on the tank you filled to the tabs.&lt;/li&gt;&#xA;&lt;li&gt;Fly around for 30-45 minutes to burn off some fuel.&lt;br&gt;&#xA;With typical fuel burns you should wind up with 6-7 gallons, or around 40 pounds of fuel left in the low tank.  That's roughly a 100lb imbalance 3 feet out on the wing.&lt;/li&gt;&#xA;&lt;li&gt;Turn into any wind, slow to around 80 knots, bring the ailerons to neutral, and wait a few seconds.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In most cases if the aircraft is rigged properly there will be a slight roll toward the full tank (heavy side). You will find you need to maintain some light aileron pressure in order to keep the wings level.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Remember to switch to the full tank after completing this little demonstration.&lt;br&gt;&#xA;You don't want the engine to quit on your way home - that would be embarrassing!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A similar demonstration can be arranged with a Cessna 172, or really any aircraft that has a fuel selector which allows you to burn fuel from one wing exclusively on demand, but you should consult the POH and/or a qualified flight instructor about the particulars of the aircraft's fuel system before you go and try this on your own. I happen to know it's relatively safe in a PA-28, but I can't speak for the fuel systems on other aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The net effect of poor lateral trim is that the pilot (or autopilot) needs to maintain some control input to counteract the aircraft's tendency to roll toward the &quot;heavy&quot; wing.&lt;br&gt;&#xA;Large aircraft (and &quot;fancy&quot; light aircraft like the Beechcraft Bonanza) have aileron trim to help out with this, but for aircraft without that particular luxury the pilot needs to hold the yoke/stick to maintain the desired control input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have mentioned, larger aircraft often have valves and pumps to transfer fuel between wing and fuselage tanks to help achieve proper lateral trim.&lt;br&gt;&#xA;The best most General Aviation aircraft can usually offer in this regard is a fuel selector that lets you burn from the left or right tanks: You burn fuel from the heavy wing until it's not heavy anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-Fuel loads can be managed in a similar way: If they're liquid provide several storage tanks and pump them around as needed (there are gliders that do this with water ballast, though I believe that's primarily for pitch trim). If they're solid (or a liquid load in fixed containers), load them so they're well balanced, and secure them so they don't shift in flight.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-01-23T05:24:21.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11935" PostTypeId="2" ParentId="11911" CreationDate="2015-01-23T08:20:28.833" Score="15" Body="&lt;h2&gt;Our Flight Environment&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First the basics: &lt;a href=&quot;http://www.wolframalpha.com/input/?i=planet%20Mars&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mars atmosphere&lt;/a&gt; is mainly carbon dioxide and has an average temperature of -47°C and an average pressure of &lt;a href=&quot;http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.004 to 0.0087&amp;nbsp;bar&lt;/a&gt;. The speed of sound in these conditions is &lt;a href=&quot;http://www.wolframalpha.com/input/?i=speed%20of%20sound%20in%20carbon%20dioxide%20at%20-47%C2%B0C%20and%200.01bar&quot; rel=&quot;nofollow noreferrer&quot;&gt;238.2&amp;nbsp;m/s&lt;/a&gt;, the dynamic viscosity $\nu$ is &lt;a href=&quot;http://www.lmnoeng.com/Flow/GasViscosity.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;1.14$\cdot 10^{-5}$&lt;/a&gt;, and for my calculations I use an atmospheric density of 0.0234&amp;nbsp;kg/m³.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Now I owe all you early upvoters an apology. The earlier answer used an unsuitable methodology; now I have improved the answer with different results.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Operating Point&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Next step: The electric power supply makes a propeller the right choice, and for propeller aircraft the minimum power to sustain flight can be achieved when the lift coefficient is&#xA;$$c_L = \sqrt{3\cdot c_{D0}\cdot\pi\cdot\Lambda\cdot\epsilon}$$&#xA;This makes your zero-lift drag the real sizing parameter: Make the aircraft a little more draggy, and you get punished with a big size increase. Therefore, we strive to keep the zero-lift drag coefficient $c_{D0}$ down to 0.008 in order to keep the aircraft small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows to get an idea which aspect ratio will be best: At minimum power the total drag is four times the zero-lift drag, and the lift coefficient should be as high as possible to keep the aircraft's size small. Realistically, our flight $c_l$ will not grow above 1.6 (which is the best that &lt;a href=&quot;http://airfoiltools.com/polar/details?polar=xf-dae11-il-1000000&quot; rel=&quot;nofollow noreferrer&quot;&gt;low-speed airfoils&lt;/a&gt; can manage at a reasonable L/D), so the aspect ratio is&#xA;$$\Lambda = \frac{c_l^2}{3\cdot c_{D0}\cdot\pi\cdot\epsilon}$$&#xA;which yields an aspect ratio of 35.74 when $\epsilon$ is 0.95.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Available Power&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now we can follow the procedure in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology/3348#3348&quot;&gt;this answer&lt;/a&gt; to calculate power demands for your solar-electric propulsion. Solar radiation on Mars is a lot lower than on Earth, but very reliable as there are no clouds to obstruct the sun. Beware of &lt;a href=&quot;http://www.universetoday.com/14892/mars-dust-storms/&quot; rel=&quot;nofollow noreferrer&quot;&gt;dust storms&lt;/a&gt;, however!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you gave the Martian solar constant in your question, I will use it here: The wing will be covered to 80% with solar cells, and each square meter of them will produce your optimistic 200&amp;nbsp;W (500&amp;nbsp;W radiation times 40% efficiency). Per square meter of wing we can achieve 160 W, and with an electric efficiency of 96% and a propeller efficiency of 85% this translates into a propulsive power per square meter of 130.5&amp;nbsp;W.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Matching Thrust to Drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now we can equate the drag $D$ and the available thrust $T$ from the power $P$, like this:&#xA;$$D = T = \frac{P}{v} =&amp;gt; 4\cdot c_{D0}\cdot S\cdot\frac{\rho\cdot v^3}{2} = 130.5\cdot S$$&#xA;Luckily, wing area $S$ can be canceled, and we get a result for the airspeed $v$ at which the aircraft's drag can just be supported by the power the wing can generate independent of wing area:&#xA;$$v = \sqrt[3]{\frac{130.5}{4\cdot c_{D0}\cdot\rho}} = 55.857 m/s$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the real size: If we assume that the payload fraction is 25%, the mass of the full aircraft will be 4&amp;nbsp;tons. To lift this at the dynamic pressure of 36.5&amp;nbsp;N/m² which corresponds to the found flight speed we need a wing area of 254&amp;nbsp;m². This can create 40.65&amp;nbsp;kW of power, 33.17 of which are transformed into thrust. The wing span will be a whopping 95.28&amp;nbsp;m. How you get this to Mars I leave to your imagination - after all, this is just a tad less than the wingspan of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hughes_H-4_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hughes H-4&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can achieve a higher payload fraction, the wing will become smaller: At 30% the full aircraft mass is only 3.333&amp;nbsp;tons, and the wing size will become 211.74&amp;nbsp;m² large. Its wing span will be 87&amp;nbsp;m. With these dimensions I doubt that a higher payload fraction will be possible. The closest aircraft to this design was the &lt;a href=&quot;http://www.boeing.com/boeing/history/boeing/condor.page&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing Condor&lt;/a&gt;, which had an empty mass of 3.6&amp;nbsp;tons (with a propulsion system weighing close to the mass of Curiosity) and a wing span of 61&amp;nbsp;m.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Last Checks&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Mach number: 56 m/s is just Mach&amp;nbsp;0.2345 on Mars, so we should not run into compressibility effects which would limit the assumed lift coefficient.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reynolds number. The bigger wing has an average chord of 2.66&amp;nbsp;m and the smaller one still 2.43&amp;nbsp;m chord, and per meter the Reynolds number in -47°C cold carbon dioxide at 56&amp;nbsp;m/s is 4,900,000 - plenty enough to make the selected lift coefficient possible. Size helps here!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-25T20:34:54.543" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11936" PostTypeId="1" AcceptedAnswerId="11948" CreationDate="2015-01-23T13:56:17.320" Score="67" ViewCount="13966" Body="&lt;p&gt;The cruising speed of large jet airliners has not increased in the past four decades. The 747 cruised at Mach 0.85 and the new Dreamliner 787 also cruises at Mach 0.85 even though it was designed 40 years later (1969-&gt;2009) and uses advanced, composite materials and more powerful and efficient engines.  Meanwhile, faster airliner designs have been shelved, most notably the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_Sonic_Cruiser&quot;&gt;Sonic Cruiser&lt;/a&gt; (Mach 0.98).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to indicate that as long as we value fuel efficiency over travel time, that we have reached peak speed efficiency at Mach 0.85 and that the only difference will be the comfort (or discomfort) of travel at that speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there fixed physical limitations at Mach 0.85 that make this the most efficient speed for jet airliners? Does this mean that even with advances in materials science and jet engine technology, we will not see significant transoceanic speed increases in the foreseeable future - so long as fuel efficiency is primary? Will airline travel forty years from now -- 2054 -- still be at Mach 0.85?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-01-24T16:27:55.707" LastActivityDate="2020-12-17T07:48:21.937" Title="Are we at peak speed efficiency for jet airliners at Mach 0.85?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11937" PostTypeId="2" ParentId="11936" CreationDate="2015-01-23T14:10:57.647" Score="29" Body="&lt;p&gt;It's not anything inherent about Mach 0.85; it's Mach 1 that's the problem. The reason airliners are usually somewhere between Mach 0.8 and Mach 0.9 is because of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;critical Mach number&lt;/a&gt; of the airframe in question. When the relative airspeed of the entire aircraft is at the critical Mach number, there will be some part of the airframe where the airflow actually reaches Mach 1. This is due to air accelerating around the airframe as the airframe moves through the air. The critical Mach number will be different for different airframes, but it's usually the limiting factor for the cruising speed of airliners. &lt;a href=&quot;https://aviation.stackexchange.com/questions/1413/how-does-exceeding-the-critical-mach-number-of-an-aircraft-affect-its-operation&quot;&gt;This question&lt;/a&gt; explains more about the critical Mach number.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-01-23T14:10:57.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11938" PostTypeId="1" CreationDate="2015-01-23T14:42:37.977" Score="2" ViewCount="312" Body="&lt;p&gt;Although rare, it seems that there has been a number of cases where airliners have crashed as a result of a high altitude stall. I tend to picture this as entailing a long, uncontrolled descent where the plane never has proper flow over control surfaces to re-establish flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any type of deployable technology that could force a plane into an attitude from which it could re-establish control? I am thinking of something like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Drogue_parachute#Use&quot; rel=&quot;nofollow&quot;&gt;drogue system&lt;/a&gt; that would force the nose down and dampen spin that could be jettisoned later.&lt;/p&gt;&#xA;" OwnerUserId="6964" LastEditorUserId="65" LastEditDate="2015-01-23T21:22:11.220" LastActivityDate="2015-01-24T09:55:13.367" Title="Is there some technology which will help in stall recovery?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11939" PostTypeId="2" ParentId="11917" CreationDate="2015-01-23T14:48:37.740" Score="1" Body="&lt;p&gt;I agree with you that the bleed air ends up colder than ambient, but not that this &quot;means that energy is wasted&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary. Once the portion of air we're using is back at ambient pressure, it will be &lt;em&gt;colder&lt;/em&gt; than before the engine took it in. That means that heat energy has been &lt;em&gt;removed&lt;/em&gt; from it. Where did that energy end up? The only place for it to go is in the wing surfaces that we wanted to heat up. (This assumes that the piping and so forth is thermally insulated so well that we can neglect unwanted heat losses there).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The net result is that the amount of heat energy deposited in the metal of the wings is &lt;em&gt;larger&lt;/em&gt; than the mechanical energy we used to compress the air in the first place. Which sounds pretty efficient to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, engineering for the de-icing air to be &lt;em&gt;warmer&lt;/em&gt; than strictly necessary after we're done with it, &lt;em&gt;that&lt;/em&gt; would be a waste.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-01-23T14:48:37.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11940" PostTypeId="1" AcceptedAnswerId="11941" CreationDate="2015-01-22T08:25:26.233" Score="2" ViewCount="236" Body="&lt;p&gt;What does the pilot use? a password? my wife identifies and authenticates herself to her car every morning using her car keys. I don't see the pilot in movies use a similar key?! I don't expect the designers to leave an airplane open for any attacker to go to the cabinet and fly away. &lt;/p&gt;&#xA;" OwnerUserId="3917" OwnerDisplayName="user1298069" LastEditorUserId="97" LastEditDate="2015-05-03T02:03:47.967" LastActivityDate="2015-05-03T02:03:47.967" Title="Which kind of identification and authentication is used to secure an airplane?" Tags="&lt;security&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2015-01-23T17:31:35.927" ContentLicense="CC BY-SA 3.0" />
  <row Id="11941" PostTypeId="2" ParentId="11940" CreationDate="2015-01-22T08:30:14.050" Score="1" Body="&lt;p&gt;Most smaller propeller planes have nothing. When you're in you can fly away. This seems to be the same for those private jets and older Boeings. I don't fly planes, but I've seen that Airplane Repo program on Discovery, and they just get in and fly away. How this works with the newest planes - no idea.&lt;/p&gt;&#xA;" OwnerUserId="6966" OwnerDisplayName="SPRBRN" LastActivityDate="2015-01-22T08:30:14.050" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11942" PostTypeId="2" ParentId="11924" CreationDate="2015-01-23T15:15:18.910" Score="9" Body="&lt;p&gt;There is no virtually no lag on attitude indicators. The traditional ones are based on a mechanical gyroscope. Due to the gyroscope being gimbaled, it remains in a fixed attitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft changes attitude, the gyroscope in the attitude indicator remains at its original orientation. When you look at the attitude indicator you are looking basically directly at the gyroscope, packed in a nice horizon displaying wrapping. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LQdKf.jpg&quot; alt=&quot;cut-away of a attitude indicator / artificial horizon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The modern attitude indicator in a glass cockpit gets the attitude information from the Attitude and heading reference system (AHRS). There is of course some lag associated with digital data transfer and display refresh rate, but these effects are too tiny to be noticeable by humans. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first generation of these systems used mechanical gyroscopes as well. Nowadays most AHRSs uses &lt;a href=&quot;http://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;noreferrer&quot;&gt;Ring Laser Gyros&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Fibre_optic_gyroscope&quot; rel=&quot;noreferrer&quot;&gt;Fibre Optic Gyros&lt;/a&gt;. These gyroscopes use &lt;a href=&quot;http://en.wikipedia.org/wiki/Sagnac_effect&quot; rel=&quot;noreferrer&quot;&gt;relativistic effects&lt;/a&gt; of light travelling clockwise and counter-clockwise through a circular path. The accuracy of these systems is very high and there is no delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another technology that is used is are Micro-electromechanical Systems (MEMS) gyroscopes. The are based on a vibrating structure. The direction of a vibration tends to remain in the original direction, even though the supporting structure rotates. MEMS are relatively cheap compared to RLG and FOG but they are less accurate. Due to developments in the automotive and mobile telephony industry where attitude sensors are used for various applications the accuracy of MEMS gyroscopes has improved while their costs have decreased. This makes them now interesting for application in avionics. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-19T08:26:40.877" LastActivityDate="2015-05-19T08:26:40.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11943" PostTypeId="2" ParentId="11940" CreationDate="2015-01-23T15:38:05.923" Score="0" Body="&lt;p&gt;For smaller aircraft there often isn't anything, but some (especially newer models) do have an ignition much like a car&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some small aircraft and many business jets have an entry key - ie for the doors. It's hard to start the engine if you can't get on board the aircraft! This is especially common for aircraft which are parked at insecure airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial airliners usually have nothing, but they are also very difficult to get to, never mind start. If you manage to get to one, sit there for long enough to start it, taxi it to a runway and takeoff..., you'd have taken long enough to alert the authorities and immediately get shot down&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-23T15:38:05.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11944" PostTypeId="1" AcceptedAnswerId="11946" CreationDate="2015-01-23T15:43:13.330" Score="4" ViewCount="3556" Body="&lt;p&gt;I was reading about &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake_turbulence&quot; rel=&quot;nofollow&quot;&gt;Wake Turbulence&lt;/a&gt; in Wikipedia and got to know about Jet Wash and Wing Vortex. According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_blast&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, Jet Blast is the movement of air from the jet exhaust. Isn't this same as Jet Wash? What is the difference between the two? &lt;/p&gt;&#xA;" OwnerUserId="4064" LastEditorUserId="679" LastEditDate="2015-01-24T03:56:18.767" LastActivityDate="2015-01-24T03:56:18.767" Title="What is the difference between Jet Wash and Jet Blast?" Tags="&lt;jet-engine&gt;&lt;wake-turbulence&gt;&lt;turbulence&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11946" PostTypeId="2" ParentId="11944" CreationDate="2015-01-23T16:12:27.247" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_blast&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jet Blast&lt;/a&gt; is the force or wind generated behind a jet engine, particularly on or before takeoff when high/full power is set, but also when the aircraft is taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4XiHJ.jpg&quot; alt=&quot;Jet Blast&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an object moves through air (or some other medium, e.g. a spoon through nutella), air is disturbed. This disturbance or &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake&quot; rel=&quot;nofollow noreferrer&quot;&gt;wake&lt;/a&gt; is known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Wake_turbulence&quot; rel=&quot;nofollow noreferrer&quot;&gt;wake turbulence&lt;/a&gt;. It can also be called &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_wash&quot; rel=&quot;nofollow noreferrer&quot;&gt;jet wash&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference is that jet blast is only because of engines. Jet wash or prop wash or wake turbulence is because the airplane moves through air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If Mr Kevin Fast runs at say 100 mph doing this (see picture below), you can notice significant wake turbulence, although the engines are off and there is no jet blast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VPZjW.png&quot; alt=&quot;Kevin Fast&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-01-24T00:42:55.600" LastActivityDate="2015-01-24T00:42:55.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11947" PostTypeId="1" CreationDate="2015-01-23T17:35:57.717" Score="0" ViewCount="75" Body="&lt;p&gt;Since it cannot be expected that the materials used for aircraft contruction have infinite lifetime and sooner or later they will deteriorate, how does aircraft maintenance work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there schedules based on which certain components have to be checked or substituted in order to prolong the aircraft lifetime? Will the aircraft be unusable anyway after a certain amount of flight hours?&lt;/p&gt;&#xA;" OwnerUserId="6967" LastEditorUserId="1467" LastEditDate="2015-01-23T17:44:56.240" LastActivityDate="2015-01-23T17:44:56.240" Title="Aircraft lifetime and maintenance" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-01-23T18:45:26.440" ContentLicense="CC BY-SA 3.0" />
  <row Id="11948" PostTypeId="2" ParentId="11936" CreationDate="2015-01-23T17:41:18.880" Score="53" Body="&lt;p&gt;Short answer: Increasing fuel prices would have driven down the most economical speed, but advances in aerodynamics have compensated for that and the maximum cruise Mach number is still at Mach 0.85. But there is a much simpler reason why this Mach 0.85 number seems so immutable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that we are talking about the maximum cruise Mach number; all airliners will fly more economical at slightly lower Mach numbers between 0.78 and 0.82. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we need to define efficiency. For airliners this is haul capacity per time, and can be expressed by the product of payload, range and speed. When none of the three constituents can be changed without making the product more costly to achieve, you have reached the point of best efficiency.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Engine Technology&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The biggest change in the last 50 years was in engine technology. Bypass ratios have increased to values close to 10, the turbine inlet temperature is now &lt;a href=&quot;http://www.aircraftenginedesign.com/TableB4.html&quot; rel=&quot;noreferrer&quot;&gt;300°C higher than in the early jet age&lt;/a&gt;, and electronic control has improved especially the off-design performance of engines. This has made it less attractive to increase flight speed, so the optimum cruise Mach would be lower if no other effects had influenced it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another effect is the lower fuel consumption. Early designs had to use a high wing chord to pack enough fuel volume for transoceanic flights. The much lower consumption of modern engines has given them ranges which are &lt;a href=&quot;http://en.wikipedia.org/wiki/Non-stop_flight&quot; rel=&quot;noreferrer&quot;&gt;more than what is needed to reach every point on earth&lt;/a&gt; directly. This made it possible to reduce wing area, thickness and mass, and to save some friction drag, helping fuel economy again. The lower thickness helps to make higher cruise Mach numbers possible.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Aerodynamics&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Aerodynamics is the second factor. With the A310 supercritical airfoils were introduced, and they shifted the operating Mach number up because now a limited region of supersonic flow on the wing could be tolerated without a significant rise in drag. However, the benefit from that was used to reduce wing sweep, increase airfoil thickness and to attach bigger fuselages to those wings. In the end, the newer airplanes had the same cruise Mach numbers as their predecessors. Something made Mach 0.85 too attractive to abandon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second effect of supercritical airfoils is their blunter nose, which helps to reach a higher maximum lift coefficient. This also contributed to reducing wing chord, because now the wing area could be made smaller for the same landing speed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Real Reason&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Every new airliner needs to compete with the older models. On fuel economy this is no problem, but &lt;a href=&quot;https://aviation.stackexchange.com/questions/3748/why-1st-and-2nd-class-but-not-fast-or-slow-airplanes/3752#3752&quot;&gt;speed is also important&lt;/a&gt;. A higher cruise Mach number allows  shorter times for connections. Now you have to know that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sabre_(computer_system)&quot; rel=&quot;noreferrer&quot;&gt;electronic&lt;/a&gt; reservation &lt;a href=&quot;http://en.wikipedia.org/wiki/Amadeus_IT_Group#History&quot; rel=&quot;noreferrer&quot;&gt;systems&lt;/a&gt; would list connections sorted by flight time, shortest first. When a travel agent wanted to book a flight, he or she would rarely look beyond the first screen and pick one of the first flights listed. If a new type made the flight slip down in the listings, it was a non-seller. This is even true in the times of online bookings: The airlines don't make much profit from the bargain hunters in Economy, their target are the business people flying in Business or First Class. And those still order mostly through travel agencies, so the rules have not changed. &lt;strong&gt;This&lt;/strong&gt; is why that Mach 0.85 speed seems to be so firmly set; flying any faster would drive up fuel consumption disproportionally, and even the newest jets will mostly be flown around Mach 0.82 to Mach 0.84.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making this speed possible is still a struggle for the design engineers, especially when you consider that larger aircraft would need thicker wings for structural efficiency, but need to be fitted with wings thinner than optimal to let marketing claim a cruise speed of Mach 0.85.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-01-24T11:16:41.110" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="11949" PostTypeId="1" AcceptedAnswerId="11964" CreationDate="2015-01-23T18:26:43.017" Score="8" ViewCount="11032" Body="&lt;p&gt;During start phase of a jet engine, igniters in the combustion chamber create sparks to initiate combustion.  As far I know, when the engine reaches self sustaining speed, igniters get turned off (this might be different (takes longer) in an Airliner due to FAA regulations during take off).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is how do flames in the combustion chamber (or canisters) get sustained (like a candle) without igniters support?&lt;/p&gt;&#xA;" OwnerUserId="6870" LastEditorUserId="65" LastEditDate="2015-01-23T19:50:08.887" LastActivityDate="2016-12-19T03:29:20.680" Title="How is combustion flame maintained in the combustion chamber after igniters are switched off?" Tags="&lt;jet-engine&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11950" PostTypeId="2" ParentId="11949" CreationDate="2015-01-23T18:37:30.953" Score="15" Body="&lt;p&gt;How does a candles flame sustain itself after you have lit it?  It stays lit by continually burning fuel.  The jet engine works the same way.  Once the fire is lit (by the ignitors) it is constantly burning.  Air is constantly being supplied by the compressor and fuel is constantly being supplied by pumps.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is fundamentally different to a traditional combustion engine you might be trying to reconcile this idea against.  In a 4-stroke internal combustion engine, for example, you have intake, compression, power and exhaust happening separately and you need spark plugs (or glow plugs) to ignite the fuel each cycle.  In a jet engine, however, instead of 4 independent cycles you have a constant flow of air through the engine.  Air comes in the front, is compressed by the N2 stage and fed continually into the hot section where the fire is constantly burning and then exhausts through the back of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at it like a propane barbecue grill or a gas stovetop -- you only need the ignitor to start the fire. Once the fire is burning it stays that way until you turn off the flow of gas.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-01-23T19:01:40.450" LastActivityDate="2015-01-23T19:01:40.450" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11951" PostTypeId="2" ParentId="11938" CreationDate="2015-01-23T18:55:35.367" Score="8" Body="&lt;p&gt;On modern airliners we have audible stall warnings (ranging in complexity from a blaring horn to a voice saying &quot;STALL. STALL. STALL.&quot;), &lt;a href=&quot;http://en.wikipedia.org/wiki/Stick_shaker&quot; rel=&quot;nofollow noreferrer&quot;&gt;stick shakers&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Stick_pusher&quot; rel=&quot;nofollow noreferrer&quot;&gt;stick &lt;em&gt;pushers&lt;/em&gt;&lt;/a&gt;, and in some aircraft sophisticated &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_envelope_protection&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight envelope protection&lt;/a&gt; systems (control software that simply won't &lt;em&gt;allow&lt;/em&gt; the pilot to stall the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When everything is working as designed these systems either make it very difficult to stall an aircraft (you would have to ignore the audible warning, ignore the stick shaker, and either override or overpower the stick pusher), or impossible to do so (flight-envelope protection).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When things are &lt;em&gt;not&lt;/em&gt; working as designed - e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;if the pitot (airspeed) and angle-of-attack systems malfunction&lt;/a&gt; these protective systems can become ineffective, however in such a scenario any other automated protection system that we would seek to implement would have similar challenges to overcome (if the flight-envelope protection system can't determine that the aircraft is in a stall how would the hypothetical &quot;stall recovery&quot; system know that it should do its thing?)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The idea of airframe parachutes - even a &quot;spin recovery drogue&quot; - for airliners &lt;a href=&quot;https://aviation.stackexchange.com/questions/9564/why-dont-big-commerical-planes-have-full-aircraft-parachutes&quot;&gt;has its own problems&lt;/a&gt; and is a largely impractical solution. (I won't rehash the reasons here, but they are well covered in the linked question.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-01-23T19:13:44.477" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11952" PostTypeId="2" ParentId="11853" CreationDate="2015-01-23T19:04:55.293" Score="-2" Body="&lt;p&gt;The short answer is the most of the world is not covered very well, not even on paper charts.  Operational Navigation Charts (ONC) are available for most of the world, but they're not approved for navigation.  That said, if there's nothing else available, an ONC chart plus GPS can still be useful. &lt;/p&gt;&#xA;" OwnerUserId="6920" LastActivityDate="2015-01-23T19:04:55.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11953" PostTypeId="2" ParentId="11659" CreationDate="2015-01-23T19:12:13.507" Score="3" Body="&lt;p&gt;As a general statement aircraft are pretty well-built (in fact, they are generally &lt;em&gt;overbuilt&lt;/em&gt; so they'll hold up to use and abuse in excess of their stated design tolerances), and carefully maintained. As such there is generally no regulatory restriction on airframe &lt;em&gt;age&lt;/em&gt;, though there may be other applicable restrictions (or recommendations) depending on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most common restriction you'll encounter that's similar to what you're asking about is what are known as &quot;life-limited parts&quot; - Aircraft components that have a finite limit (expressed in flight hours, flight cycles, or calendar time), after which they must be replaced or overhauled.&lt;br&gt;&#xA;These limitations are usually given by the manufacturer (in a &lt;strong&gt;Limitations&lt;/strong&gt; section of the POH/AFM or Maintenance Manual, which has regulatory effect under FAA rules).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases an entire airframe may be life-limited: (&lt;a href=&quot;https://aviation.stackexchange.com/a/11660/64&quot;&gt;The R22 helicopter&lt;/a&gt; has both a calendar and hours limit,  and commercial airliners typically have a flight cycle and flight hour limitation on the airframe as well.&lt;br&gt;&#xA;In other cases only a &lt;em&gt;component&lt;/em&gt; may be life-limited: The wings on a &lt;a href=&quot;http://en.wikipedia.org/wiki/Grumman_American_AA-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Grumman Tiger&lt;/a&gt; or a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-38_Tomahawk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper Tomahawk&lt;/a&gt; must be replaced after a certain number of flight hours.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Even in absence of a specific limitation it's important to recognize that all airframes have a finite life - components will eventually suffer fatigue and fail, as with any kind of mechanical equipment. Manufacturers may recommend extensive inspections of older aircraft to ensure that fatigue is detected before the structure fails. (For example, while the Piper Cherokee family has no &lt;em&gt;Limitations&lt;/em&gt; published &lt;a href=&quot;http://bsd-box.net/~mikeg/N8031W/SB_SL/SB%20886.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper does recommend extensive inspections&lt;/a&gt; on aircraft that have accumulated a large amount of flight time.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-01-23T19:12:13.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11954" PostTypeId="2" ParentId="11938" CreationDate="2015-01-23T19:29:57.397" Score="5" Body="&lt;p&gt;The real problem is complacency and over-reliance on technology. There is no technological fix for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots have been made to believe that their computerized FCS will make stall impossible. When the system switches modes and the pilots do not become aware of this, they have in very few cases actively &lt;a href=&quot;http://avherald.com/h?article=41a81ef1/0037&amp;amp;opt=4096&quot; rel=&quot;nofollow&quot;&gt;kept the aircraft in a stall&lt;/a&gt;, thinking they wouldn't stall, ever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is needed is better pilot training, and maybe less exposure to the propaganda from the aircraft manufacturers. Trusting the life of 300 people to a person who has never flown upside down, not to mention at bank angles of more than 60°, is reckless. In their race to ever lower cost the MBA types who run airlines today compare pilots to coach drivers and put as much effort in their education.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-24T09:55:13.367" LastActivityDate="2015-01-24T09:55:13.367" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="11955" PostTypeId="2" ParentId="3370" CreationDate="2015-01-23T22:01:44.907" Score="3" Body="&lt;p&gt;I'll challenge your assumption that there aren't many cars on the road more than 10-15 years old, since my two are 15 and 27 years old, and cars this age are far from rare hereabouts (western US).  Of course this can vary: if you live in the US northeast, where they make a practice of spreading corrosive chemicals on the roads, your car's body might fall off in a few years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd add two reasons to yours:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;There was a period of a couple of decades where few if any new GA airplanes were built, for fear of liability.&lt;/li&gt;&#xA;&lt;li&gt;Planned obsolescence: auto makers come out with &quot;new&quot; (that is, different sheet metal) models every year, so that the gullible will buy the new designs in order to follow fashion.  That's hard for aircraft makers to do when the basic shape of the plane is dictated by aerodynamics rather than style.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The much higher price for a new plane only makes it harder still.&lt;/p&gt;&#xA;" OwnerUserId="6968" LastEditorUserId="65" LastEditDate="2015-01-23T22:09:28.993" LastActivityDate="2015-01-23T22:09:28.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="11956" PostTypeId="1" CreationDate="2015-01-23T22:28:47.990" Score="12" ViewCount="4057" Body="&lt;p&gt;Turbojets have largely been superseded by turbofans (or turboprops for low-speed flight). Are there any aircraft being planned that would use turbojets?  I'm also interested whether there has been any improvement in turbojet design over the last few decades.&lt;/p&gt;&#xA;" OwnerUserId="558" LastActivityDate="2015-06-15T23:05:16.097" Title="Do any manufacturers have plans to use turbojets in future aircraft? What is the state-of-the-art in turbojet design?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11957" PostTypeId="2" ParentId="11956" CreationDate="2015-01-23T22:40:22.463" Score="15" Body="&lt;p&gt;The first jets were turbojets simply because the turbine could only support its own compressor. They kept an edge for &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593&quot;&gt;supersonic flight&lt;/a&gt; and will be the engine of choice if we ever design another &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot;&gt;Mach 3+&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot;&gt;aircraft&lt;/a&gt;. Also, micro jets for cruise missiles and model aircraft turbines are turbojets to keep them simple. However, the analysis of modern jet warfare showed that the overwhelming majority of flight time is spent at high subsonic speeds, and there a turbofan makes more sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now all modern combat jet aircraft use &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F100&quot;&gt;turbofans&lt;/a&gt;, even though their bypass ratio is rather low (around 0.5).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial jet transport engines are solidly turbofans since half a century and have slowly increased their &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot;&gt;bypass ratio to about 9&lt;/a&gt;, less for smaller engines. Now &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent&quot;&gt;three-spool engines&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Geared_turbofan&quot;&gt;geared turbofans&lt;/a&gt; are state of the art, because they allow more freedom in optimizing the rotation speed of the different sections inside the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbojets have benefited from better, more heat-resistant materials and airfoils for turbo machinery just as much as turbofans, but modern designs are overwhelmingly turbofans, so turbojets generally represent a much earlier technological level. To give you an example: The first turbojet used in operation, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_004&quot;&gt;Jumo 004&lt;/a&gt;, had a mass of more than 700 kg and produced 8.8 kN of thrust. The engine of the Eurofighter, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot;&gt;EJ200&lt;/a&gt;, is only slightly bigger in mass and has similar dimensions, weighing 990 kg, but produces seven times the thrust of the Jumo 004. With reheat, thrust is more than 10 times that of the Jumo 004, which had no afterburner. The pressure ratio could be increased from 3.2 to 26 (that is the progress in compressor aerodynamics), and the turbine entry temperature from &lt;a href=&quot;http://www.allworldwars.com/Performance-Investigation-of-a-Jumo-004-Combustor-by-Robert-Miller.html&quot;&gt;840°K&lt;/a&gt; to 1800°K (that is the progress in materials). &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-06T23:50:48.093" LastActivityDate="2015-06-06T23:50:48.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11959" PostTypeId="2" ParentId="11949" CreationDate="2015-01-24T01:54:13.600" Score="3" Body="&lt;p&gt;To add to casey's post, the flame holder keeps the flame from getting blown out. Its a part of the combustion chamber that allows the high pressure air from the final compression stage to swirl at a low speed to keep the flame front contained.&lt;/p&gt;&#xA;" OwnerUserId="6971" LastActivityDate="2015-01-24T01:54:13.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11960" PostTypeId="1" CreationDate="2015-01-24T02:56:12.557" Score="5" ViewCount="632" Body="&lt;p&gt;It is suggested by &lt;a href=&quot;http://www.iasa.com.au/folders/Safety_Issues/FAA_Inaction/Continental_Flt3407.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;some&lt;/a&gt; (and somewhat substantiated) that twin-engine propeller aircraft which do not have counter-rotating props (all modern regional turboprops are this way) can develop asymmetric wing icing due to the airflow pattern generated by the propellers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UYJOj.jpg&quot; alt=&quot;Asymmetric icing photo&quot;&gt; (from the FAA FFFSCR report, via the linked source)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has it been demonstrated that twins with counter-rotating props (are any such twins rated for FIKI?) are immune to this asymmetric icing phenomenon?  What about quad-turboprop planes such as the A400M, with its Down Between Engines configuration?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="167" LastEditDate="2015-02-01T22:52:17.507" LastActivityDate="2015-02-01T22:52:17.507" Title="Are aircraft with counter-rotating props or Down Between Engines less likely to develop asymmetric icing?" Tags="&lt;safety&gt;&lt;propeller&gt;&lt;icing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11961" PostTypeId="2" ParentId="11909" CreationDate="2015-01-24T03:43:34.463" Score="2" Body="&lt;p&gt;The ATC guys can't just do whatever they want. They have to operate within guidelines - they will have an ATC handbook/manual etc, much like a pilot has a flight operations manual, which has been merticulously developed and approved by the authorities. There are references in this manual as to when ATC can cancel speed restrictions, or deviate from the other usual procedures. In most cases it will read something like &quot;Speed restrictions under 10,000 feet may be cancelled in Class C airspace only, and if the controller is satisfied that no risk of LOSA (loss of separation assurance) exists&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in practical terms, ATC do have the ability to deviate from most of the usual procedures, but always within existing guidelines. Of course, everything goes out of the window in an emergency, however. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-01-24T03:43:34.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11962" PostTypeId="2" ParentId="3785" CreationDate="2015-01-24T05:36:29.273" Score="4" Body="&lt;p&gt;Though rather belated, &lt;strong&gt;FOR THE OP's Question&lt;/strong&gt;:&#xA;  The wing's downward push on the air under it is a good start.  Pushing down on some bunch of air causes the wing to be pushed up. This is Newton #3 and what I call The Natural Phenomenon of &quot;Paired Forces&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I use the example of pushing off from a boat to jump to the dock.  The boat then moves away.  You can even talk about loading the boat with more mass to reduce its movement to avoid falling in (as shown on many &quot;funny&quot; videos).  The more mass (of boat, or air) that is pushed, the less it has to be accelerated.   Watching tests and doing some calculations you can see this mass of air accelerated to about 30 ft per second for a large airliner. (F=MA)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also mention helicopter downwash, an ordinary propeller propwash, or a jet engine jet blast for examples of the &quot;push on something and get pushed the other way&quot; of Newton's #3. The explanation of pressures and pressure gradients around the wing to accomplish this gets longer than a 9 year old probably needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, scientists discovered that the air moving over the top must curve around and follow that upper surface and this (details omitted) also causes more air to be pushed down and adds to the lift.  Detail explaining why the upper surface effect occurs gets more complex and it must be well understood before attempting to explain it and only if necessary. (The &quot;longer path&quot; does not cause it to speed up.  It has to do with accelerating air around a curve)  The student can accept that there is more that they won't understand and can be satisfied by a partial, but correct, explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure where that climbing part is going, but it is always the relative motion of the wing through the air (called &quot;Relative Wind&quot;) that is important, not the climb angle. I believe you refer to the &quot;Angle of Attack&quot; (AOA).  This is the angle that the wing makes as it meets the relative wind. If the nose is pointed up, but it is flying more or less level, this is because more lift is needed, USUALLY at low speed, when airspeed, and therefore lift is lower.  At some point, as the angle of the wing points up too far, the smooth flow of air OVER THE TOP turns turbulent.  It swirls around instead of following the wing smoothly and this destroys that upper flow and a large part of the lift.  This is called &quot;stall&quot;.  This is proof that it is not juswt the lower surface that produces lift, otherwise the loss of smooth flow over the top would be a 'don't care'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the fan &lt;strong&gt;over&lt;/strong&gt; the wing is actually a &lt;strong&gt;GOOD&lt;/strong&gt; idea.  This uses what is called the Coanda Effect and has been used on aircraft.  The first I was aware of, as a youth, was the F-104 with its tiny wings.  In order to reduce the landing speed (and actually make it landable -- no engine, no land---bail out) they directed some engine blast-air through carefully designed slots over the wing. It was called &quot;Boundary Layer Control&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PLEASE, &lt;strong&gt;all readers&lt;/strong&gt;, see these authoritative sources.  They discuss lift and you should be able to adapt parts of them and simplify as needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Peter Eastwell Bernoulli?&lt;br&gt;&#xA;&lt;a href=&quot;http://www.scienceeducationreview.com/open_access/eastwell-bernoulli.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.scienceeducationreview.com/open_access/eastwell-bernoulli.pdf&lt;/a&gt; &#xA;  As a teacher, he didn't like what he read and researched this to find the truth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weltner in PDF - &quot;Misinterpretations of Bernoulli's Law&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://user.uni-frankfurt.de/~weltner/Misinterpretations%20of%20Bernoullis%20Law%202011%20internet.pdf&quot; rel=&quot;nofollow&quot;&gt;http://user.uni-frankfurt.de/~weltner/Misinterpretations%20of%20Bernoullis%20Law%202011%20internet.pdf&lt;/a&gt;   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd post more links, but I'm limited.  Google can find them...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prof Babibski @ Cambridge has a youtube video, but you must get his slides from links under the video. XWdNEGr53Gw&lt;/p&gt;&#xA;&#xA;&lt;p&gt;His missing slides are at docs.google.com&lt;br&gt;&#xA;/file/d/0B0JABuFvb_G_MkpBZHJmRGo3UkU/edit?usp=sharing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He also has a comparable paper on ww3.eng called &quot;Senior-glider/howwingswork.pdf&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anderson &amp;amp; Eberhardt AAPT paper: The &quot;Newtonian Description of Lift of a Wing&quot;-Revised 2009:  on  comcast.net/~clipper-108/Lift_AAPT.pdf   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;gifday.com has a great animated GIF of an A380 test allowing you to actually see the downwash: 2012/02/a380.gif &lt;/p&gt;&#xA;&#xA;&lt;p&gt;-- &#xA;Regards, Challenger Learning Center Science/Technical Advisor&#xA;Steve N.&lt;/p&gt;&#xA;" OwnerUserId="6972" LastEditorUserId="6972" LastEditDate="2015-01-26T06:50:08.587" LastActivityDate="2015-01-26T06:50:08.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11963" PostTypeId="2" ParentId="3785" CreationDate="2015-01-24T06:47:21.650" Score="5" Body="&lt;p&gt;It works, but it is just the wings. For a controlled flight, we'd need two big fans for the wings (one for each), two smaller fans for the elevators, and one more for the rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So that's 5 fans for each airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept of controlled flight can be demonstrated by hanging two strings to any model airplane (plastic ones recommended, model airplanes stall just like real planes...). If we want to pitch up or down, we would need at least 3 strings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another consequence of having the fans blow air backwards across the wing is, due to action and reaction, there is a thrust pushing the plane forward. That's not a bad thing, planes are designed to move forward to get from A to B, not create lift vertically then settle down exactly where it started.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the 5-fan plane will move forward anyway. Engineers figured out it is better to have one fan, called the &quot;propeller&quot;, at the nose of the plane instead of 5.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-24T06:47:21.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11964" PostTypeId="2" ParentId="11949" CreationDate="2015-01-24T07:44:00.990" Score="10" Body="&lt;p&gt;Another answer to add to caseys:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flow speed near the fuel injectors is very slow, on the order of 30 m/s. This is caused by a widening of the flow path between compressor exit and combustor called a diffusor or diffuser. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-on-direction-to-the-gas-turbine/11752#11752&quot;&gt;here&lt;/a&gt; for more.&lt;/li&gt;&#xA;&lt;li&gt;Radiation from the burning fuel-air mixture in the middle part of the combustor heats up the not-yet-burning mixture near the fuel injectors, which helps the fuel droplets to evaporate (this is a necessary step before combustion can start) and causes the mixture to be heated above its &lt;a href=&quot;http://en.wikipedia.org/wiki/Autoignition_temperature&quot; rel=&quot;nofollow noreferrer&quot;&gt;autoignition temperature&lt;/a&gt;. Hence, this radiated heat will provide the fuel-air mixture with the needed activation energy for combustion. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Some combustors have small notches in their wall which create local turbulence and help to keep some of the burning fuel-air-mixture back, which helps to start ignition in the following flow. These are called flame holders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all of the burning gas is washed out from the combustion chamber without igniting the following gas, the ignition process will stop. This is called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Flameout&quot; rel=&quot;nofollow noreferrer&quot;&gt;flame-out&lt;/a&gt;. The heat from the walls of the combustion chamber will not be enough to re-ignite the fuel-air mixture, because they are cooled by the airflow from the compressor and will rapidly cool down once the flame is blown out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this effect is used to extinguish &lt;a href=&quot;https://www.youtube.com/watch?v=LjM12xDlSX0&quot; rel=&quot;nofollow noreferrer&quot;&gt;burning oil or gas wells with dynamite&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-01-24T09:51:24.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11966" PostTypeId="1" AcceptedAnswerId="11970" CreationDate="2015-01-24T12:12:12.277" Score="20" ViewCount="2009" Body="&lt;p&gt;I was thinking through my flying experiences when I remembered a strange sensation while I was a student.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a Robinson R22, with about 35 hours experience, I was doing a solo flyout to a nearby airfield for a cup of coffee and a look at the weekend traffic.  To get there, I had to cross a MATZ which included some permanent danger areas up to 2,500 feet.  I'd transited this MATZ several times with a call to the tower but on this particular occasion, I couldn't reach anyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being quite inexperienced, I didn't know if it was just unmanned, I had the wrong frequency or something else so I decided, with no particular place to go, to climb to 3,000 feet and go over the top.  One lesson learned is how long it takes to get to 3,000 feet in a Robbo, especially in a climbing spiral :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone who has been in an R22 will know that the visibility is superb and as I climbed, the views were spectacular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I got to 3,000 feet and leveled off, I had this strange sensation.  It felt as if the aircraft was balanced on top of a tall pole and the cabin had shrunk to really small. I felt as if the aircraft might tip off the top of this pole and plunge.  I also found it difficult to believe the 70kts indicated since the apparent speed over the ground was so low which makes sense given that I'd only ever been that high as a passenger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I really didn't feel comfortable although I wasn't scared, didn't have any anxiety and felt fully in control of myself but I did abandon the plan, got back down to the 1,000 feet I was more used to and completed a couple of circuits at my home field before landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What did I experience?  Has anyone else had anything like this?  I guess that it might be a symptom of vertigo but I have never had problems before or, perhaps something weird in my ear canals following the long spiral climb followed by a level out?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="65" LastEditDate="2015-03-17T20:19:19.593" LastActivityDate="2015-03-17T20:19:19.593" Title="Why was I getting an uncomfortable feeling in an R22 at 3,000 feet?" Tags="&lt;helicopter&gt;&lt;medical&gt;&lt;altitude&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11967" PostTypeId="1" AcceptedAnswerId="11968" CreationDate="2015-01-24T12:33:04.287" Score="12" ViewCount="10853" Body="&lt;p&gt;The lifespan of aircraft is generally limited by &lt;a href=&quot;https://aviation.stackexchange.com/questions/2263/what-is-the-lifespan-of-commercial-airframes-in-general/2264#2264&quot;&gt;metal fatigue&lt;/a&gt;. This is true for fixed wing aircraft; is it also true for helicopters? What is the determining factor for helicopter useful life?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2018-10-25T16:29:03.253" Title="What limits the lifespan of helicopters?" Tags="&lt;helicopter&gt;&lt;airframe&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11968" PostTypeId="2" ParentId="11967" CreationDate="2015-01-24T12:55:44.473" Score="10" Body="&lt;p&gt;Helicopters are also subject to metal fatigue and there have been accidents attributed to it but the primary determination is component life times.  All of the engine, transmission and rotor parts are lifed and most of the control mechanisms.  Depending on the helicopter, there will be many more lifed components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helicopters also have fixed intervals between major overhauls by the manufacturer.  For example, the R22 is effectively rebuilt to an &quot;as new&quot; standard by Robinson at 2,200 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Corrosion might also play a part.  There may be a time when it is just not economical to continue to repair and service the airframe.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-24T13:51:43.667" LastActivityDate="2015-01-24T13:51:43.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11969" PostTypeId="1" AcceptedAnswerId="11972" CreationDate="2015-01-24T13:28:10.523" Score="18" ViewCount="3606" Body="&lt;p&gt;In commercial aviation, it seems jet engines grow and bypass ratio increase with newer engines. Here is some examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1963: bypass ratio: 0.96 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT8D&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W JT8D&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;1970: bypass ratio: 5.0 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W JT9D&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;1984: bypass ratio: 5.3 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW4000&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W PW4000&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;1984: bypass ratio: 6.0 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT8D&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W PW2000&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;2004: bypass ratio: 8.5 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Trent_900&quot; rel=&quot;noreferrer&quot;&gt;Rolls-Royce Trent900&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;2007: bypass ratio: 10.8 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot; rel=&quot;noreferrer&quot;&gt;Rolls-Royce Trent1000&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;2015: bypass ratio: 12.0 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW1000G&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W PW1124G&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The bypass ratio has been multiplied by nearly 2 in 30 years (1970 -&gt; 2015).&#xA;I understand the need of really high bypass ratio to decrease fuel consumption while increasing thrust. To have big bypass ratio, the high pressure part of the engine must be small compare to the overall size of the engine. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What prevent jet engine designer to design smaller high pressure part or bigger jet engines to increase the bypass ratio? &lt;/li&gt;&#xA;&lt;li&gt;Is there someone that has made prediction about the increasing bypass ratio in the next decades and written it in a serious article?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="62" LastEditDate="2019-11-10T20:51:09.580" LastActivityDate="2019-11-10T20:51:09.580" Title="What prevents jet engine designs with larger bypass ratios?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="11970" PostTypeId="2" ParentId="11966" CreationDate="2015-01-24T13:54:15.950" Score="22" Body="&lt;p&gt;Typical height for helicopters is 500-1,500 AGL, and almost all flights are conducted in this regime. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below 1,500 AGL the surface is quite close and the ground moves by fairly quickly, so you have a good point of reference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 3,000 AGL, you can feel quite disconnected from the earth and can have a bout of altitude fear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I had to circle up above out of a valley airport in an airplane, with minimum VFR visibility due to smoke, I felt like I had to keep cross-checking my instruments to maintain airspeed and bank angle. It was an uncomfortable feeling, even having had lots of hood time and actual IMC. So its not unusual for unusual flight regimes to have an unsettling effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The circling could have also cause some disorientation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important thing, which you accomplished, is recognizing the signs, not panicking, and you kept flying. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-24T14:38:19.587" LastActivityDate="2015-01-24T14:38:19.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11971" PostTypeId="2" ParentId="287" CreationDate="2015-01-24T15:00:03.913" Score="2" Body="&lt;p&gt;The answer to your question can be found in 91.123:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 91.123 Compliance with ATC clearances and instructions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) When an ATC clearance has been obtained, no pilot in command may&#xA;  deviate from that clearance unless an amended clearance is obtained,&#xA;  an emergency exists, or the deviation is in response to a traffic&#xA;  alert and collision avoidance system resolution advisory. However,&#xA;  except in Class A airspace, a pilot may cancel an IFR flight plan if&#xA;  the operation is being conducted in VFR weather conditions. &lt;strong&gt;When a&#xA;  pilot is uncertain of an ATC clearance, that pilot shall immediately&#xA;  request clarification from ATC.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Telling the controller you are a student pilot when you are not is not an acceptable way to &quot;&lt;em&gt;immediately request clarification&lt;/em&gt;&quot; from ATC when you are uncertain of your clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine you're a JAL pilot flying a 777 into JFK and you have a problem understanding the controller from Queens. Would it be acceptable to say &quot;Student Pilot?&quot; Of course not, because its a lie, and its still a lie if you're banging around in a 152 under part 91 holding a private pilots license (or better).&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-24T15:00:03.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11972" PostTypeId="2" ParentId="11969" CreationDate="2015-01-24T16:42:55.457" Score="15" Body="&lt;p&gt;For ungeared two-spool designs, bypass ratios cannot be increased further. Since the fan is coupled to the low-speed turbine, increasing it would overload the turbine. Only if the engine is run at a higher core temperature can the power provided by the low-speed turbine be increased. This would require either better materials (which are not available) or lower times between overhauls (which are costly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the engines of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent&quot; rel=&quot;noreferrer&quot;&gt;Rolls-Royce Trent&lt;/a&gt; family have the biggest bypass ratios. Rolls-Royce went with three-spool designs which allow for a finer adjustment of the speed of the different engine components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a &lt;a href=&quot;http://en.wikipedia.org/wiki/Geared_turbofan&quot; rel=&quot;noreferrer&quot;&gt;reduction gearbox is placed between fan and turbine&lt;/a&gt;, even a two-spool design can support a larger fan, and this solution will be used in the next generation of &lt;a href=&quot;http://www.pw.utc.com/PurePowerPW1000G_Engine&quot; rel=&quot;noreferrer&quot;&gt;P&amp;amp;W&lt;/a&gt; engines. Smaller engines like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lycoming_ALF_502&quot; rel=&quot;noreferrer&quot;&gt;ALF 502&lt;/a&gt; which is used in the &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Aerospace_146&quot; rel=&quot;noreferrer&quot;&gt;BAe 146 rsp. Avro RJ&lt;/a&gt;, used this already years ago to fit a fan to a single-spool engine. For bigger engines, transmitting the enormous power in a compact gearbox was too challenging until now. Just the heat generated by the gearbox of a 200 kN thrust class engine running at 98% efficiency would be almost 400 kW - this needs to be shed somehow!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another problem remains, however. Bigger fans need bigger nacelles, and their drag increases with the square of the fan diameter increase. Increasing the bypass ratio of a high-bypass engine even further yields diminishing returns, which tend to be compensated by the increased nacelle drag once the bypass ratio grows beyond 12 to 15. To make bigger bypass ratios economical, active laminarisation on the nacelle will be needed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-25T09:11:05.217" LastActivityDate="2015-01-25T09:11:05.217" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11974" PostTypeId="2" ParentId="1323" CreationDate="2015-01-24T19:05:02.760" Score="0" Body="&lt;p&gt;The controlling regulation for Part 91 flights is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;91.9 — Civil aircraft flight manual, marking, and placard requirements. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraph (d) of this section, &lt;strong&gt;no person may&#xA;  operate a civil aircraft without complying with the operating&#xA;  limitations specified in the approved Airplane or Rotorcraft Flight&#xA;  Manual&lt;/strong&gt;, markings, and placards, or as otherwise prescribed by the&#xA;  certificating authority of the country of registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;the word &quot;limitation&quot; in this section refers specifically to SECTION 4 LIMITATIONS in the POH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 182 you mentioned, the demonstrated crosswind number comes from SECTION 1 INTRODUCTION.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you are not &lt;em&gt;prohibited&lt;/em&gt; from taking off with a 16kt cross-wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an accident with a 16kt crosswind where the crosswind is a factor in the accident, you will still be subject to 91.13:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 91.13 — Careless or reckless operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Aircraft operations for the purpose of air navigation. No person&#xA;  may operate an aircraft in a careless or reckless manner so as to&#xA;  endanger the life or property of another.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Aircraft operations other than for the purpose of air navigation.&#xA;  No person may operate an aircraft, other than for the purpose of air&#xA;  navigation, on any part of the surface of an airport used by aircraft&#xA;  for air commerce (including areas used by those aircraft for receiving&#xA;  or discharging persons or cargo), in a careless or reckless manner so&#xA;  as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="753" LastEditDate="2018-11-15T11:59:26.877" LastActivityDate="2018-11-15T11:59:26.877" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="11975" PostTypeId="1" AcceptedAnswerId="11979" CreationDate="2015-01-24T19:15:16.490" Score="7" ViewCount="7146" Body="&lt;p&gt;On Cirrus' &lt;a href=&quot;http://cirrusaircraft.com/2015/&quot; rel=&quot;nofollow&quot;&gt;2015 aircraft page&lt;/a&gt;, they advertise Baro-VNAV capability in the new model. Having never done an LNAV/VNAV GPS approach (only LNAV or LPV), I'm wondering: when would I actually use it, if I already have WAAS and can just use the LPV approach? Typically, I'm used to seeing an LPV minima alongside any LNAV/VNAV minima. Are there exceptions? Is this feature valuable in practice?&lt;/p&gt;&#xA;" OwnerUserId="2124" LastEditorUserId="62" LastEditDate="2015-01-24T23:02:17.220" LastActivityDate="2015-01-24T23:02:17.220" Title="What is the benefit of having baro-VNAV in addition to a WAAS GPS?" Tags="&lt;approach&gt;&lt;gnss&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11979" PostTypeId="2" ParentId="11975" CreationDate="2015-01-24T20:02:59.210" Score="6" Body="&lt;p&gt;LPV and non-baro LNAV/VNAV requires that a Space-Based Augmentation System (SBAS) be available to the GPS receiver.  In the United States, that system is called Wide Area Augmentation System (WAAS).  Similar services operate in other parts of the world (e.g. EGNOS in Europe, MSAS over Japan, GAGAN over India) but coverage is not worldwide, and not all GNSS (Global Navigation Satellite System) approaches are approved for LPV.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having a baro-VNAV system in the aircraft allows you to shoot LNAV/VNAV approaches if SBAS is not available. While not as useful in the United States, as we have robust and reliable coverage with WAAS, it is nice to have in parts of the world where SBAS is unreliable or non-existent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA fact sheet on RNAV (GPS) approaches: &lt;a href=&quot;http://goo.gl/cIhIJa&quot;&gt;http://goo.gl/cIhIJa&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Worldwide SBAS information: &lt;a href=&quot;http://goo.gl/eooOau&quot;&gt;http://goo.gl/eooOau&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-01-24T20:02:59.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11980" PostTypeId="2" ParentId="11975" CreationDate="2015-01-24T20:03:07.833" Score="1" Body="&lt;p&gt;Baro-VNAV computes vertical navigation based on barometric pressure, rather than on GPS-based WAAS altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altimeter feeds digital altitude information into the RNAV/VNAV unit, and the RNAV/VNAV unit provides vertical navigation information to the pilot by computing a synthetic glideslope, to guide the airplane from the FAF down to DH above the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One major factor for Baro-VNAV is temperature, which cannot be set in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Paul_Kollsman&quot; rel=&quot;nofollow&quot;&gt;Kollsman Window&lt;/a&gt; of the altimeter, so these approaches have a minimum OAT at which they can be utlized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/factsheets/media/RNAV_QFSheet.pdf&quot; rel=&quot;nofollow&quot;&gt;RNAV (GPS) Approaches&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-24T20:03:07.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11982" PostTypeId="2" ParentId="11909" CreationDate="2015-01-24T21:23:39.947" Score="7" Body="&lt;p&gt;As an active area radar controller, I completely agree with @rbp answer.&#xA;To better explain relationship between power and responsibility, I will try to describe what a controller would usually do: If I need an aircraft, for example, to reduce speed...&#xA;I know approx. what would be the minimum convenient speed for a particular type to ask, so I'd take this into account prior asking. But if a pilot tells me that he's unable to comply with the request, I'll find another solution i.e. radar vectoring to loose few miles or in extreme situation, level change. In short, a controller will never force a pilot to action if pilot answers that he can't do that. A controller must plan in advance that pilot may not be able to fulfil his request and have alternative solution. If you, as a controller, put yourself in a situation where you have no alternative, that is usually too late.&#xA;There are usually only few things where I can't make exception:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Minimum separation between aircraft&lt;/li&gt;&#xA;&lt;li&gt;Danger/Prohibited zone&lt;/li&gt;&#xA;&lt;li&gt;Terrain&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Even then, in extreme case, I've never met: Imagine a situation where you have an aircraft which can't change level due to traffic above and below and has a crossing traffic. Then only remaining action I have available is radar vectoring, but what if the pilot advises me that his unable to turn due to weather, (the described situation is usually the controller fault because he should have predicted that earlier). Then controller probably would give the pilot traffic information (tell the pilot what to expect) and advise the minimum distance but it will not force the aircraft to CB.&lt;/p&gt;&#xA;" OwnerUserId="6978" LastEditorUserId="19" LastEditDate="2015-01-24T21:45:17.313" LastActivityDate="2015-01-24T21:45:17.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11983" PostTypeId="1" CreationDate="2015-01-24T22:03:58.207" Score="3" ViewCount="591" Body="&lt;p&gt;It seems the EU granted some hundreds of thousand € to a non-engineer, to study a cargo airplane with a turning cylinder in the leading edge, to produce increased lift by the Coanda/Magnus effect also used in the Flettner rotor sails for ships. As the concept seems having been discarded because of the important gyroscope effect of the turning barrel: anybody commenting about technical reasons for this revival of a discarded concept?&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="1696" LastEditDate="2015-02-05T16:49:26.890" LastActivityDate="2015-02-05T16:49:26.890" Title="What is the feasibility of a Coanda/Magnus effect wing airplane?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11984" PostTypeId="1" AcceptedAnswerId="11987" CreationDate="2015-01-24T22:51:36.800" Score="10" ViewCount="7754" Body="&lt;p&gt;I live in Atlanta, GA well north of the airport and typically there is very few large, commercial aircraft that pass overhead. But there is an on-going security issue at the airport today and there are some really low-flying commercial jets passing from east-west over my house at altitudes that look like they would be on final approach (if they weren't 40 miles north of the runways anyway). There is a military airport near by and we frequently have C-130's landing but they don't come from that direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I really have no idea what those planes were doing or where they were going, and in the 5 years I've lived here there have never been commercial planes that flew that pattern. At another place I hang out, close to the airport, I've noticed that air traffic passes over when there are storms at the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would imagine this is a &quot;something is wrong at the airport&quot; pattern as opposed to a normal operating pattern, and it may even be something that was specific to that particular aircraft for some reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any way to look up what patterns would pass over a given location under what situations? Or more likely -- how can I look up what patterns are around an airport and how those patterns change with conditions (weather, emergency, traffic, etc)?&lt;/p&gt;&#xA;" OwnerUserId="6842" LastEditorUserId="13197" LastEditDate="2016-04-27T21:24:39.563" LastActivityDate="2016-04-28T07:46:32.307" Title="How can I find traffic patterns that pass over my house?" Tags="&lt;commercial-aviation&gt;&lt;airport&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11985" PostTypeId="1" CreationDate="2015-01-24T23:07:28.103" Score="-1" ViewCount="49" Body="&lt;p&gt;I've come across a JetStar flight (JQ 28 on 3 February 2015) that's flying from Sydney to Melbourne which departs and arrives in international terminals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My assumption is that it's part of an international flight - that is, it's flying from somewhere overseas to Sydney, and then going on to Melbourne, or that it's flying from Melbourne onwards to somewhere overseas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in whether it's coming from Japan. How can I find out what the full international route is?&lt;/p&gt;&#xA;" OwnerUserId="2250" LastActivityDate="2015-01-24T23:17:34.677" Title="Determining full route of domestic leg" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-01-25T07:37:45.183" ContentLicense="CC BY-SA 3.0" />
  <row Id="11986" PostTypeId="2" ParentId="11985" CreationDate="2015-01-24T23:17:34.677" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;FlightAware.com&lt;/a&gt; is a good resource for this sort of thing. When you look up a flight, you can click &quot;Track inbound flight&quot; under the flight ID. If &lt;a href=&quot;http://flightaware.com/live/flight/JST28/history/20150119/1400Z/VTSP/YSSY&quot; rel=&quot;nofollow&quot;&gt;the trip on January 19th/20th&lt;/a&gt; is any indication, it arrived from Phuket, Thailand before continuing to Melbourne.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-01-24T23:17:34.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11987" PostTypeId="2" ParentId="11984" CreationDate="2015-01-25T00:25:15.093" Score="8" Body="&lt;p&gt;Its not that easy for a non-pilot to do it, but &lt;a href=&quot;http://www.airnav.com/airport/KATL&quot; rel=&quot;noreferrer&quot;&gt;there are about a dozen&lt;/a&gt; &quot;Arrival Procedures&quot; that show specific routes into ATL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see on the &lt;a href=&quot;http://skyvector.com/?ll=33.724351464022355,-84.36712107256577&amp;amp;chart=460&amp;amp;zoom=3&quot; rel=&quot;noreferrer&quot;&gt;Atlanta Area Chart&lt;/a&gt; how some of the traffic might flow near your house.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The easiest thing to do, if you can pick out some of the aircraft, is to &lt;a href=&quot;http://flightaware.com/live/airport/KATL/arrivals&quot; rel=&quot;noreferrer&quot;&gt;look up their flight paths on Flightaware&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aDu5K.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-25T00:25:15.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11988" PostTypeId="2" ParentId="11918" CreationDate="2015-01-25T00:37:01.643" Score="3" Body="&lt;p&gt;If we take the question as it is, I will say that never ever any point of the surface of any airplane will be at Mach &gt; 1. Close to the surface, at typicial airliner, exist an thin layer of air that adapts the speed from outside to the speed of the airplane. So, the air at the surface of the airplane is at velocity relative to the airplane of 0. So the Mach = 0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This layer is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Boundary_layer&quot; rel=&quot;nofollow&quot;&gt;boundary layer&lt;/a&gt; and, in typical airliners, some centimeters over the the edge of the surface of the airplane the air will recover the speed and everything that has been mentioned will apply (and so there will be points close to the surface where the Mach will be &gt; 1).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question seems as well focused in the cruise condition, however, when high lift devices are deployed (flaps and slats) the acceleration on the upper surface is much bigger, you can have one or several points &quot;close to the surface&quot; where the Mach is 1 having the airplane flying at relatively low Mach number (0.3-0.5). This depends strongly of the high lift devices used by the airplane.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2015-01-25T11:00:35.337" LastActivityDate="2015-01-25T11:00:35.337" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="11989" PostTypeId="2" ParentId="11801" CreationDate="2015-01-25T01:07:23.717" Score="2" Body="&lt;p&gt;I think you were asking this question related to wing physics and not to airfoil physics. Here comes the physics of &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift-induced_drag&quot; rel=&quot;nofollow&quot;&gt;induced drag&lt;/a&gt;. I will try to simplify the explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you might know, the upper surface of the wing has lower pressure and the lower part of the wing has higher pressure. This is what is producing lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But... what about the tip of wing? Both sides are in contact so they should be at the same pressure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, we have a lower surface of the wing with higher pressure and the tip with &quot;normal pressure&quot;, so, naturally in the lower surface the air will try to go from the root to the tip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the upper surface the situation is the opposity, the root will have lower pressure and the tip higher, so the air will try to go from the tip to the root.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As in the tip both sides are connected, the air will try to scape from the lower to the upper level (that's why there are wing tips). And that's why the tip vortexes are created with the typical &lt;a href=&quot;http://en.wikipedia.org/wiki/Wingtip_vortices#mediaviewer/File:Airplane_vortex_edit.jpg&quot; rel=&quot;nofollow&quot;&gt;pictures&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, now let's talk about drag. Drag is actually &quot;any energy we are losing just because we fly&quot; (ok, is a simplification but allows me to explain the next step). So, the airplane is losing energy and gives it to the air to create the tip vortex. The bigger the tip vortex the more energy is lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, know coming to the question, why efficiency (L/D) decreases? So, as the angle of attack increases the lift increases linearly (proportional to the increase of the angle), however, the energy lost in the tip vortex (that is a component of drag) increases quadratically (proportional to the square of the angle of attack), that means that the drag is increasing more quickly (but starting at a lower level) that lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(lift grows, but drag grows proportionally faster)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, we reach a point where the increase of drag makes the efficiency starting to decrease. That point can be calculated with the formula provided in the previous post.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that the physics of the wing is more complicated as there are other drag components also interacting with the wing. It is also true that &quot;infinite&quot; wings have a maximum L/D, but there is a different mechanism in place.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-01-25T01:07:23.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11990" PostTypeId="1" CreationDate="2015-01-25T01:49:02.290" Score="10" ViewCount="29285" Body="&lt;p&gt;In relation to AirAsia flight QZ8501 &lt;a href=&quot;http://www.bbc.com/news/world-asia-30964705&quot;&gt;officials have been quoted as saying&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;It is not normal to climb like that. It's very rare for commercial planes, which normally climb just 1,000 to 2,000 feet per minute. It [climbing at 6,000 ft per minute] can only be done by a fighter jet.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Two parts of that statement struck me:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The rate of 1,000 to 2,000 feet per minute is stated as &quot;normal&quot;, not &quot;maximum&quot;&lt;/li&gt;&#xA;&lt;li&gt;The claim that only fighter jets can climb at 6,000 feet per minute.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;My question is then:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the maximum climb rate that an AirBus A320-200 such as the one involved in this incident could achieve with out stalling? (Including configurations and operations outside of &quot;normal&quot;)&lt;/li&gt;&#xA;&lt;li&gt;If it is less than 6,000 feet per minute on the A320-200 can any commercial passenger carrying aircraft in operation today exceed 6,000 feet per minute? (I'd assume Concorde could, but that's no longer in operation)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4269" LastEditorUserId="572" LastEditDate="2015-02-25T07:26:53.807" LastActivityDate="2018-06-18T09:07:31.573" Title="What climb rates can the Airbus A320-200 achieve and which climb rates are commonly used for normal flight operations?" Tags="&lt;stall&gt;&lt;airbus-a320&gt;&lt;vertical-speed&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="11991" PostTypeId="1" AcceptedAnswerId="11993" CreationDate="2015-01-25T02:46:31.560" Score="4" ViewCount="18574" Body="&lt;p&gt;I am going from Canada to Mexico but I don't want to be dependent on in-flight entertainment. Thus I got &lt;a href=&quot;http://www.amazon.ca/Seagate-Wireless-Built-In-Streaming-STCK1000100/dp/B00AQRUW4Q&quot; rel=&quot;nofollow&quot;&gt;seagate wireless plus&lt;/a&gt; so I can stream to my iPad. I couldn't find any policies I can use this device during flight or not. At very least I am trying to determine if it is worth asking the flight company?  &lt;/p&gt;&#xA;" OwnerUserId="6981" LastEditorUserId="65" LastEditDate="2015-01-25T15:03:23.577" LastActivityDate="2015-07-26T01:09:12.853" Title="Are those devices allowed on a flight which create their own WiFi signals?" Tags="&lt;regulations&gt;&lt;inflight-entertainment&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11992" PostTypeId="1" AcceptedAnswerId="11995" CreationDate="2015-01-25T02:50:05.677" Score="7" ViewCount="17121" Body="&lt;p&gt;The typical aviation headset features two cords with connectors that at first glance are identical. One is a standard 1/4&quot; (0.25 inch) stereo audio jack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of connector is the slightly smaller, slightly narrower one?&lt;/p&gt;&#xA;" OwnerUserId="6982" LastEditorUserId="1467" LastEditDate="2016-04-08T08:03:05.603" LastActivityDate="2019-09-18T16:47:41.507" Title="What connector standard is used for aviation headsets?" Tags="&lt;radio-communications&gt;&lt;cockpit&gt;&lt;avionics&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11993" PostTypeId="2" ParentId="11991" CreationDate="2015-01-25T02:55:51.220" Score="4" Body="&lt;p&gt;No, the rules are about &lt;strong&gt;any&lt;/strong&gt; transmitter or receiver, regardless of whether it comes under the specific category of phone/tablet/laptop etc&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anything your device is worse as it transmits at a higher power and range than a receiver.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-25T02:55:51.220" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="11994" PostTypeId="2" ParentId="11990" CreationDate="2015-01-25T03:01:28.437" Score="16" Body="&lt;p&gt;There's a lot of nonsense being banded about regarding this flight.&lt;/p&gt;&#xA;&lt;p&gt;First up, we are not talking about sustained, powered climb rates. If you're travelling at Mach 0.85 and pull up vertically, in theory (if your plane didn't break) you'd climb at an initial rate of nearly Mach 0.85 (your original speed minus the airspeed loss when pulling up).... That's near enough 57,000 feet/minute.&lt;/p&gt;&#xA;&lt;p&gt;If you're at high speed and willing to trade speed for altitude, an Airbus A320 is physically capable of climbing at much higher rates than 6000 feet per minute.... At least until it runs out of airspeed.&lt;/p&gt;&#xA;&lt;p&gt;A fighter is the only aircraft which would be likely to perform a sustained 6000ft/minute climb rate in normal use, but they're also capable of much higher rates of climb.&lt;/p&gt;&#xA;&lt;p&gt;The maximum rate of climb you'd see in an A320 in normal use is in the 2000 ft/min range, but that's because it's the highest reasonably efficient rate of climb. That's not the maximum the aircraft is capable of under power (which is more in the region of 4000 ft/min), and is absolutely no indication of that maximum unsustained climb rate.&lt;/p&gt;&#xA;&lt;p&gt;It would eventually stall at any unsustainable rate of climb, but then again, so would any aircraft even at a sustainable rate... Keep climbing and before too long you run out of atmosphere.&lt;/p&gt;&#xA;&lt;p&gt;Either way, there is nothing to say that climbing above the sustained climb rate for an aircraft is unsafe or, necessarily, unusual. You trade airspeed for altitude, sure, but if you need to be higher at that moment in time, there's plenty of time to accelerate again later.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/109744/&quot; rel=&quot;noreferrer&quot;&gt;Airlines.Net&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The three are roughly the same at 10,000', at about 2500 fpm. (Maybe a bit more for a light A319, and less for a full A321)&lt;/p&gt;&#xA;&lt;p&gt;Normal climb rates from 10,000' to about 30,000 are as follows:&lt;/p&gt;&#xA;&lt;p&gt;A319, 3000 fpm to about 1500 at 30,000'&lt;/p&gt;&#xA;&lt;p&gt;A320, 2200 fpm to about 1000 at 30,000'&lt;/p&gt;&#xA;&lt;p&gt;A321, 1400 fpm to about 500 at 30,000'&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR - The official is spouting nonsense s/he doesn't understand. A fighter is the only aircraft likely to be able to (or wish to) climb at a 6000 ft/minute SUSTAINED climb rate, but almost any aircraft can climb at that rate for brief durations in a &lt;em&gt;zoom climb&lt;/em&gt; - converting airspeed/momentum to altitude&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-05T16:54:19.767" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="11995" PostTypeId="2" ParentId="11992" CreationDate="2015-01-25T03:36:29.397" Score="7" Body="&lt;p&gt;It's for the microphone (the standard sized one is for the head phones). They are different size so the pilot knows to try the other hole if it doesn't fit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/Phone_connector_%28audio%29#Aircraft_headsets&quot; rel=&quot;noreferrer&quot;&gt;wikipedia:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Commercial and general aviation (GA) civil airplane headset plugs are&#xA;  similar, but not identical. A standard 1⁄4 in monaural plug, type&#xA;  PJ-055, is used for headphones, paired with special tip-ring-sleeve,&#xA;  0.206 inch diameter plug, type PJ-068, for the microphone. On the microphone plug the Ring is used for the microphone 'hot' and the&#xA;  sleeve is common or microphone 'Lo'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-25T03:36:29.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="11996" PostTypeId="1" AcceptedAnswerId="12008" CreationDate="2015-01-25T05:15:57.123" Score="14" ViewCount="1930" Body="&lt;p&gt;In an unrelated answer rbp linked to this &lt;a href=&quot;http://www.airnav.com/airport/KATL&quot;&gt;Atlanta airport&lt;/a&gt; info page, and runway 8R/26L caught my eye. If I understand correctly, these two runways are the same piece of pavement, but refer to the use of the runway in opposite directions. According to that page, 8R has a gradient of &quot;1.0% DOWN,&quot; but 26L has a gradient of &quot;0.4% DOWN.&quot; It seems like a physical impossibility - if one is sloped down, the other must sloped up, right? So what am I missing?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2015-01-25T16:43:59.027" Title="How can the same runway have two different gradients?" Tags="&lt;airport&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11997" PostTypeId="1" AcceptedAnswerId="11998" CreationDate="2015-01-25T07:12:02.550" Score="2" ViewCount="911" Body="&lt;p&gt;Some of the supersonic fighter jets (such as F-4 Phantom and F-5) have narrow waist on their fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FBWKV.gif&quot; alt=&quot;for F-4&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1TxUF.png&quot; alt=&quot;and for F-5&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do these fighter jets have narrow waist?&lt;/p&gt;&#xA;" OwnerUserId="6870" LastActivityDate="2015-01-25T14:55:27.513" Title="Why do super sonic fighter jets have narrow waist?" Tags="&lt;supersonic&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-01-25T19:09:40.650" ContentLicense="CC BY-SA 3.0" />
  <row Id="11998" PostTypeId="2" ParentId="11997" CreationDate="2015-01-25T07:36:53.080" Score="5" Body="&lt;p&gt;It is likely due to application of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;nofollow&quot;&gt;Area rule&lt;/a&gt;, which helps to reduce drag due to shock waves in transonic and supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It basically is an attempt to keep the cross-sectional area of the craft from varying rapidly as you move along the length.  So at a point where the wings area is increasing a lot, the area of the fuselage may be reduced to compensate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This reduction of area is mainly intended when these airplanes fly at transonic speeds (0.8-1.2) but not when flying at supersonice speeds where a front shock wave is created.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="6979" LastEditDate="2015-01-25T14:55:27.513" LastActivityDate="2015-01-25T14:55:27.513" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="11999" PostTypeId="2" ParentId="11983" CreationDate="2015-01-25T09:05:04.613" Score="3" Body="&lt;p&gt;A lot of research grants are wasted on scams or projects making exorbitant claims. See it this way: The people who judge an idea grant-worthy need to spend the money they have available somehow, and if they were clever enough to pick winners all the time, they would not work in a government bureaucracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, who is to judge what idea is really good before it has been tried? You have to accept some losses if you want to move outside of safe bets - only then can new ground be broken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA funded a &lt;a href=&quot;http://en.wikipedia.org/wiki/Julian_Wolkovitch&quot; rel=&quot;nofollow&quot;&gt;researcher&lt;/a&gt; for more than three decades who was only working on joined wing projects. It's easy to see that they are a non-starter, but this guy built his career on that particular hoax.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-01-25T09:05:04.613" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12001" PostTypeId="1" AcceptedAnswerId="12004" CreationDate="2015-01-25T09:45:47.880" Score="9" ViewCount="2081" Body="&lt;p&gt;Wherever I read about shock waves, it is mentioned that there is a reduction in speed across the shock wave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone please explain what happens at the molecular level, i.e. the physics of the problem?&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="5517" LastEditDate="2015-02-19T20:41:11.927" LastActivityDate="2017-10-24T07:12:42.990" Title="What causes the reduction in speed across the shockwave?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12002" PostTypeId="2" ParentId="11991" CreationDate="2015-01-25T10:05:20.170" Score="-2" Body="&lt;p&gt;The airlines will be primed to say No. But you will hardly be the only one on board with an iPad so it's unlikely anyone will notice. Turn it off if the plane suddenly pitches nose-down at the beginning of your movie.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I question the need. I have a 32Gb iPad and there's absolutely no way I can watch a full load of video on my entire vacation, never mind the flight at each end.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-01-25T10:05:20.170" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12003" PostTypeId="2" ParentId="12001" CreationDate="2015-01-25T10:06:19.720" Score="10" Body="&lt;p&gt;If you look what causes the shock, there must be an obstruction at the root of it. See the sketch below for a straight and an oblique compression shock:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TYi8X.png&quot; alt=&quot;straight and oblique shock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the straight shock this can be a blunt body or an intake filled with slower moving air of higher pressure. In case of the oblique shock this is clearly the bend in the wall contour which forces the flow to change direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The index 1 denotes conditions ahead of the shock, and 2 those downstream of the shock. For weak straight shocks the product of the speed ahead of the shock $v_1$ and the speed past the shock $v_2$ equals the square of the speed of sound: $$v_1\cdot v_2 = a^2$$&#xA;If we call the local &lt;a href=&quot;https://en.wikipedia.org/wiki/Mach_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mach number&lt;/a&gt; $Ma$, and if $Ma_1 &amp;gt; 1$, then $Ma_2$ must be smaller than 1, so the flow is always decelerated to subsonic speed by a straight shock. The same holds for the normal component of an oblique shock: It also becomes subsonic. Since the total energy of the gas doesn't change, its pressure, density and temperature rise when it is decelerated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incremental pressure change $\delta p$ due to the bend with an incremental angle of $\delta\vartheta$, expressed in terms of the undisturbed flow with the index $\infty$, is proportional to the change in the streamlines:&#xA;$$\delta p = -\frac{\rho_{\infty}\cdot v^2_{\infty}}{\sqrt{Ma^2_{\infty} - 1}}\cdot\delta\vartheta$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gas pressure on a molecular level is the number and severity of particle collisions&lt;/a&gt;. The air molecules experience more collisions on the downstream side of the shock, since air pressure is higher there. The average  direction of the additional collisions is indeed orthogonal to the shock, because it is the boundary between blissfully unaware molecules at ambient pressure ahead of the shock and their bruised brethren downstream which have just crossed that boundary. Once a molecule has passed the shock, the collisions are coming again equally from all sides and its speed does not change any more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In subsonic speeds this pressure change can radiate in all directions and becomes a shallow pressure gradient. In supersonic speed, no information about the upcoming pressure change can travel forward, so the change is concentrated in the shock front.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-24T07:12:42.990" LastActivityDate="2017-10-24T07:12:42.990" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12004" PostTypeId="2" ParentId="12001" CreationDate="2015-01-25T11:30:02.563" Score="4" Body="&lt;p&gt;The mechanism is not as complicated as might seem in a first glance. First thing, what's a supersonic flow? Is a flow where the speed of the air is higher that Mach &gt; 1 and if we are talking about air that is coming from an upstream subsonic flow the air will be at lower pressure (that is what is happening on the upper surface of a wing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, high speed air with low pressure that tries to move along the wing up to the end of the wing (the trailing edge), but at the end of the wing the air is at the upstream subsonic pressure... so, air at a higher presure usually tries to go into low pressure air... but the supersonic air has a lot of inertia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally we end up having air of high speed very difficult to stop... we are talking about very high speeds and the only way the air can adapt is in a very small space with a shock wave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the mechanism that is called &quot;shock wave in adverse pressure gradient&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another mechanism that has been described above, supersonic flow agaisnt obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine that we have a supersonic flow moving towards a step, or a ramp... obviously the air has again the same high inertia, is supersonic!!! But the air &quot;does not know&quot; that there is a ramp. Why not? Because the information within fluid moves at the speed of sound, the molecules of the air that bound of the ramp are not able to reach fast enough the other molecules fast enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So... a high inertia flow moves towards a ramp and suddently notices a ramp that the flow was not adapting before and needs to adapt!!! So does it suddently in a very similar way as before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to understand the mechanism is by looking at the waves that are created when we throw a stone into water. What happens when they approach to the shore? They continue as there is no shore until, suddently they notice it and they die or bound on it. Is the same mechanism (actually the same!!! supersonic moves in &quot;waves&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, just to remark that shock wave has a finite size, is really small but is not a 0 thickness surface. Notice that we have an area where a high speed is transformed into low speed in a very small space. There the viscosity plays some effect.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-01-25T11:30:02.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12005" PostTypeId="2" ParentId="11991" CreationDate="2015-01-25T11:42:25.290" Score="0" Body="&lt;p&gt;The intention behind is to isolate the electronic devices of an airplane from electromagnetic radiation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern airplanes are pretty well protected at the moment and they don't have any issue of isolation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, one thing that is key for authorities is flight safety. So it is better to have stronger restrictions that making any mistake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in order to be able to use wifi on the airplane, you need to have, first the airplane modern enough and the airline shall be authorized by the authorities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, in any case those radiation devices should be turned off (or in airplane mode) when flying in take-off or landing stages (so the wifi of the airplane does).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My recommendation: ask the airline directly and get information about the airplane you are flying in.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="774" LastEditDate="2015-07-26T01:09:12.853" LastActivityDate="2015-07-26T01:09:12.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12006" PostTypeId="1" AcceptedAnswerId="12007" CreationDate="2015-01-25T13:34:13.403" Score="23" ViewCount="8912" Body="&lt;p&gt;How do military helicopters like the Blackhawk and CH-53, as well as the V-22 Osprey, perform mid-air refueling without their rotor blades (periodically and accidentally) contacting the drogue or fuel hose and causing a major accident?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0N5gR.jpg&quot; alt=&quot;Black Hawk refueling from a C-130&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine that if the rotor blades did make contact with the fuel hose, either the fuel would be released and be sparked and ignite, or ingested by the helicopter turbines, or the rotor would break, or all of the above!  When a helicopter is refueling, its rotor is nearly above the fuel hose, or at the maximum, maybe 20 feet away?  It's easy to imagine a bit of turbulence or a few centimeters of cyclic movement (a sneeze perhaps?) is all that it would take for the rotor to dip and come forward and contact the hose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the Osprey the propellers / rotors are behind the nose of the aircraft and thus farther away from the fuel hose, but still, like a helicopter the Osprey's rotors are very large, and are exposed as opposed to the concealed compressor blades of a jet turbine.&lt;/p&gt;&#xA;" OwnerUserId="5730" LastEditorUserId="62" LastEditDate="2019-06-02T00:47:22.037" LastActivityDate="2020-09-13T14:26:21.947" Title="How is it safe for helicopters and Ospreys to refuel in mid-air?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;refueling&gt;&lt;v-22&gt;&lt;uh-60&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="12007" PostTypeId="2" ParentId="12006" CreationDate="2015-01-25T14:59:09.753" Score="35" Body="&lt;p&gt;That photograph distorts the perspective.  Just Google for &quot;helicopter air-to-air refueling&quot; and look at the image results.  &lt;a href=&quot;https://www.google.co.uk/search?q=helicopter%20air%20to%20air%20refueling&amp;amp;es_sm=122&amp;amp;biw=1920&amp;amp;bih=955&amp;amp;tbm=isch&amp;amp;source=lnms&amp;amp;sa=X&amp;amp;ei=fwTFVMqGB9CV7Ab03IHADQ&amp;amp;ved=0CAgQ_AUoAQ&amp;amp;dpr=1#imgdii=_&amp;amp;imgrc=km9XxC7Xxe8vkM%253A%3B22Cj2Nc_LAeCgM%3Bhttp%253A%252F%252Fdmna.ny.gov%252Fpressroom%252Fimages%252FAerial%252520refueling%252520over%252520Louisiana.jpg%3Bhttp%253A%252F%252Fdmna.ny.gov%252Fpressroom%252F%253Fid%253D1220809204%3B1029%3B684&quot; rel=&quot;noreferrer&quot;&gt;Many show other perspectives&lt;/a&gt; from which you can see that it is not possible for the blades to contact the hose or basket - the probe is longer than those on a fixed-wing craft for exactly that reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Uk9n9.jpg&quot; rel=&quot;noreferrer&quot; title=&quot;Click for larger view.&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uk9n9l.jpg&quot; alt=&quot;Better view of refueling probe&quot; title=&quot;Click for larger view.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=VAdpKpppZiA&quot; rel=&quot;noreferrer&quot;&gt;This video shows a CH-53E Super Stallion chopping off it's own probe&lt;/a&gt; through over-controlling the cyclic, but that particular mishap would be possible in other flight phases too.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-28T22:50:39.720" LastActivityDate="2015-01-28T22:50:39.720" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12008" PostTypeId="2" ParentId="11996" CreationDate="2015-01-25T16:43:59.027" Score="23" Body="&lt;p&gt;The slope of a runway isn't always constant. In some cases, for example, if you stand at one end of the runway, you can't see the opposite end, because the runway goes up then down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the ICAO (in the airport design manual) computes the runway slope as follows: the runway is divided into four equal segments. The average slope of each segment is computed and the total slope follows this formula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[(slope of 1st quarter) + 1.33*(slope of 2nd quarter) + 2.33*(slope of 3rd quarter) + 3.33*(slope of 4th quarter)] / 8&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway slope has a greater influence when the aircraft has a greater speed. Therefore, the slope at the end of the runway is given a greater weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case that you mention, if you walk from the west side of the runway to the east side of the runway, you will go up a little, then down, and end up at a lower altitude than when you started.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-01-25T16:43:59.027" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12009" PostTypeId="1" AcceptedAnswerId="12104" CreationDate="2015-01-25T18:18:51.660" Score="12" ViewCount="1416" Body="&lt;p&gt;Many years ago, I was part of a LRRP drop taking photos from inside a &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_KC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;KC-130&lt;/a&gt; aircraft. The rear doors are (relatively speaking) huge. The top half pivots up and into the craft, while the bottom half descends down and (I assume) into the airstream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the main doors are opened like that, how does that affect the stability and controllability of the airplane? Would the pilot have to trim down or up, or do nothing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While my personal experience is that plane, I wonder of any plane that opens large portals into the airstream.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2017-12-11T15:29:37.460" LastActivityDate="2017-12-11T17:41:38.343" Title="What effects to controllability are there when the rear doors are opened on a KC-130?" Tags="&lt;aerodynamics&gt;&lt;safety&gt;&lt;flight-controls&gt;&lt;skydiving&gt;&lt;c-130&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12010" PostTypeId="5" CreationDate="2015-01-25T18:39:50.300" Score="0" Body="&lt;p&gt;Special VFR -- used to clear VFR flights through controlled airspace in conditions that are below normal VFR minima, but above Special VFR minima.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use this tag for all questions related to Special Visual Flight Rules (SVFR) clearances, whether issued to fixed-wing or rotary-wing aircraft.  SVFR can only be issued in controlled airspace upon request of the PIC of the flight, and is normally used in terminal areas where slow-flying VFR aircraft can safely fly in prevailing weather that is below normal VFR minima, say due to a low ceiling.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;SVFR, of course, has its own set of visibility minima (1500m worldwide, 1 mile in the US).  It is most commonly used with helicopters as they can fly slowly enough to navigate safely in mildly restricted visibility without reference to instruments, provided visibility is sufficient to allow reference to the ground, although fixed-wing aircraft can request and receive SVFR as well.  Some jurisdictions, such as the US, restrict the use of SVFR clearances to IFR-rated pilots and aircraft under certain circumstances.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="8547" LastEditDate="2015-06-23T09:51:11.397" LastActivityDate="2015-06-23T09:51:11.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12011" PostTypeId="4" CreationDate="2015-01-25T18:39:50.300" Score="0" Body="Special VFR -- used to clear VFR flights through controlled airspace in conditions that are below normal VFR minima, but above Special VFR minima." OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-01-25T19:35:18.620" LastActivityDate="2015-01-25T19:35:18.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12012" PostTypeId="1" AcceptedAnswerId="12013" CreationDate="2015-01-25T20:08:41.743" Score="27" ViewCount="4515" Body="&lt;p&gt;I was watching &lt;a href=&quot;http://youtu.be/rEf35NtlBLg&quot;&gt;this Swiss Air video&lt;/a&gt;. It's a flight from Zurich to Shanghai. Shortly after take off they have high engine oil temp in engine 3 and end up shutting it down. They declare a pan-pan-pan, dump fuel and return to Zurich. It's pretty uneventful, engine shut down aside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, as I understand it, an air crew's pay begins upon push-back, and ends at gate arrival. At the very end the PIC states that for the passengers, Swiss Air has another plane which will be departing in two hours, but with a new crew. Assuming this crew gets no other flights for the day, did they just get only 1 - 1.5 hours pay for the day?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: even though this is a Swiss Air flight, I am not concentrating on that one airline. I'm curious if there are general rules for flight pay that all/most airlines follow.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2015-01-27T08:34:24.330" LastActivityDate="2015-01-27T22:39:25.793" Title="How do airlines pay air crews for an aborted flight, in general?" Tags="&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12013" PostTypeId="2" ParentId="12012" CreationDate="2015-01-25T21:04:45.720" Score="35" Body="&lt;p&gt;How the Swiss Air pilots got paid would, of course, depend on Swiss Air policy. I suspect pay policies vary greatly between airlines and countries, but for what it's worth below are the pay policies for the four airlines I worked for in the 1980s and 1990s. At all four I would have been credited with only the time from push back until the parking brake was set on return insofar as flight time was concerned, but as you will see that wouldn't have made any significant difference in my pay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;commuter #1 no union -- a straight salary but with an hourly addition if your flight time went over a minimum, which it never did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;commuter #2 no union -- a straight salary regardless of the number of hours flown, but they never abused that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;747 freight carrier no union -- a straight salary plus an hourly addition if your flight time went over a minimum, which it occasionally did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;747 passenger carrier in-house union -- flight time hourly pay with a guaranteed minimum. You always went substantially over the minimum. They tried to get you as close as possible to the regulatory max of 1000 hours a year. Additionally, they had a policy that whenever your duty time (as opposed to flight time) went over 16 consecutive hours, you got paid for each hour over that at a rate of 1.5 times your regular hourly flight time rate. Also, you were paid half your regular hourly flight rate while deadheading. Then, if you had less than 8 hours (I might not be remembering that number correctly) between assignments, your duty time continued. My first assignment for this airline was a 32-hour duty day. I operated from JFK to AMS (Amsterdam), so my duty time started at show time, 2 hours before departure. At Amsterdam 5 hours on the ground then commercialling (riding in the back on another airline) to SIN (Singapore) and then to CGK (Jakarta) positioning for a Hajj flight. Crew scheduling regularly abused pilots, but nobody complained because you were being so well paid when they did abuse you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The breakdown for hours at the flight time rate for that trip was approximately:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;7.5 hours operating time JFK-AMS&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;8 hours deadheading pay AMS-SIN-CGK (half of 16 hours riding in the back)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;24 hours extended duty pay (32 hours duty time minus 16 hour threshold times 1.5)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, 39.5 pay hours at the regular new first officer rate of 55 per hour = 2,172.50, which looked pretty good to me since I had come from a carrier than paid me a straight 4500 per month salary as a 747 captain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't remember all the flight time/duty time details, but back then at least the international rules were much less restrictive than the domestic rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, back then it was common practice to do things like scheduling a flight for, say, 11:59 for regulatory purposes, when everyone knew it would go slightly over the 12-hour international rule of the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be worth noting here, that the mind-set of the crew, at least the cockpit crew, is totally different from that of passengers. The passenger wants to get from point A to point B, whereas the crew is simply 'at work' regardless of whether they go anyplace or not. Consequently, at least in my experience and opinion, delays aren't nearly as frustrating to crew as they are to passengers.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-01-26T04:31:44.777" LastActivityDate="2015-01-26T04:31:44.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12014" PostTypeId="2" ParentId="11960" CreationDate="2015-01-25T22:12:40.980" Score="4" Body="&lt;p&gt;Ice accretion is a very complex phenomenon on airplanes that depends on several factors. One of the main factor is the composition of the cloud that the airplane is flying and the exposure time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another significant effect are the conditions on the imprigment surface on the airplane, which depends of the flow path and the pressure over the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, having the properlers rotating in the same direction means that the propellers are providing energy in a different direction. Also that will mean that, for optimizing the airplane, the fuselage will be slightly assymetric (very difficult to notice).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to the first statement you are mentioning, I can confirm you that the imprigment areas affected by this assymetric effect will develop different ice shapes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I can tell you is that FAA and EASA employ real experts for airplane certification and they are concious of this effect, and I can tell you that any doubt they have about aircraft performances will request the manufacturer to demonstrate in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My answer to your question is that those airplanes are not protected in the sense that they will develop assymetric iced conditions but are strongly protected in the sense that this condition is considered and very likely tested with airtificial iced shapes, so the airplanes are really safe. So globally, yes, the airplane is &quot;protected&quot; by design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your questions about 4-engined airplane, the answer is the same but having more complexity due to the number of engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can tell you as well that in iced conditions, due to the complexity of the phenomena and the prediction and simulation difficulties, there is a lot of conservatism in the way manufacturers design the airplane and significant cost in airplane testing. FAA and EASA are really doing a good job.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="755" LastEditDate="2015-02-01T19:50:40.450" LastActivityDate="2015-02-01T19:50:40.450" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12015" PostTypeId="1" AcceptedAnswerId="12029" CreationDate="2015-01-25T22:59:22.797" Score="3" ViewCount="325" Body="&lt;p&gt;Original discussion &lt;a href=&quot;https://aviation.stackexchange.com/questions/11929/lateral-cg-imbalances&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does weight and balance for rotary wing aircraft work?  Is lateral CG more or less of an issue, or is it comparable to fore/aft CG since the lifting surface is rotating around the aircraft?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the major differences compared to fixed wing, if any?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-02-19T20:06:30.650" Title="Are the implications of weight and balance for rotary wing aircraft similar to fixed wing aircraft?" Tags="&lt;weight-and-balance&gt;&lt;rotary-wing&gt;&lt;cg&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12016" PostTypeId="2" ParentId="149" CreationDate="2015-01-25T23:33:00.650" Score="20" Body="&lt;p&gt;Big difference is on Boeing with a yoke, it is like two linked steering wheels in a  car.  The pilot not flying can easily see what the other pilot is doing with his controls, as the yoke in front of him moves along with the other pilot's inputs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the airbus models with a side stick, the pilot not flying cannot see what the other pilot is asking of the controls.  This contributed to the situation where Air France stalled and fell into the sea without the pilot in the left seat realizing that the pilot in the right seat had his controls calling for full pitch up.  (The opposite of what would get them out of a stall.)&lt;/p&gt;&#xA;" OwnerUserId="6984" LastEditorUserId="755" LastEditDate="2015-01-26T01:37:16.927" LastActivityDate="2015-01-26T01:37:16.927" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12017" PostTypeId="2" ParentId="12012" CreationDate="2015-01-26T01:22:55.390" Score="13" Body="&lt;p&gt;A common pay scenario for US pilot unions is known as &quot;block or better&quot;.  In the case of an aborted flight like you example, you would be credited the scheduled block time toward your monthly pay guarantee under those rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specifics of any pay questions will fall under the collective bargaining agreement (union) or company policy (non-union) of the specific company involved.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-01-26T01:22:55.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12018" PostTypeId="2" ParentId="11991" CreationDate="2015-01-26T01:43:22.193" Score="1" Body="&lt;p&gt;Airlines provide WiFi onboard and invite you to connect to it (for a fee). To connect to WiFi you must have the ability to transmit (internet requires two way communications). If your device is conforms to FCC power limits on the 2.4GHz bands (or whatever your particular jurisdictions regulatory body is) then your device is no different than any other WiFi device on the plane. They are &lt;em&gt;all&lt;/em&gt; transmitters using the same maximum power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your airplane has WiFi onboard and let's you connect computers to it then there is no technical problem with using your device. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if a crew member tells you to turn it off, remember you must comply. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-01-26T01:43:22.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12019" PostTypeId="2" ParentId="7922" CreationDate="2015-01-26T02:27:41.687" Score="10" Body="&lt;p&gt;In addition to @Relaxed's answer, one additional reason would be if the hijacker gets control of the cockpit and turns off the transponder. ATC works on secondary radar with a signal bounced back from the plane in order for ATC to track the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the transponder is turned off, it would be very difficult for ATC to track the exact whereabouts of the plane. By having escort planes, they could maintain positioning of the endangered aircraft.&lt;/p&gt;&#xA;" OwnerUserId="6986" LastActivityDate="2015-01-26T02:27:41.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12020" PostTypeId="5" CreationDate="2015-01-26T02:58:29.917" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-01-26T02:58:29.917" LastActivityDate="2015-01-26T02:58:29.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12021" PostTypeId="4" CreationDate="2015-01-26T02:58:29.917" Score="0" Body="A measurement of vertical distance. Usually measured at either Mean-Sea-Level (MSL) or Above-Ground-Level (AGL)." OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-01-26T05:58:43.477" LastActivityDate="2015-01-26T05:58:43.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12022" PostTypeId="2" ParentId="12006" CreationDate="2015-01-26T03:12:07.923" Score="5" Body="&lt;p&gt;The probe is the furthest point forward on the Pave hawk helicopter. It also has an IR sensor to properly line up the boom(the female end). Obviously the procedure for approach is to come from behind to avoid such things from hitting the rotor blades.&lt;/p&gt;&#xA;" OwnerUserId="6987" LastActivityDate="2015-01-26T03:12:07.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12023" PostTypeId="2" ParentId="11967" CreationDate="2015-01-26T03:18:57.513" Score="0" Body="&lt;p&gt;Most helicopters will go though some sort of &quot;Phase&quot; of &quot;Depot&quot; inspections where different components will be replaced due to life-span requirements. For example; a uh-60L will require a shock strut replacement every 1500 flight hours to prevent a collapse of the strut due to over use.&lt;/p&gt;&#xA;" OwnerUserId="6987" LastActivityDate="2015-01-26T03:18:57.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12024" PostTypeId="2" ParentId="11731" CreationDate="2015-01-26T03:25:38.917" Score="2" Body="&lt;p&gt;Yes. Some will use a &quot;trim&quot; function to hold the cyclic or collective stick in place to prevent rapid changes in the blades pitch. Some blades also have &quot;trim tabs&quot; and are critical component on the blade and require adjustment to ensure the smoothest flight.&lt;/p&gt;&#xA;" OwnerUserId="6987" LastActivityDate="2015-01-26T03:25:38.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12025" PostTypeId="2" ParentId="7922" CreationDate="2015-01-26T03:42:38.463" Score="5" Body="&lt;p&gt;In addition to the reasons above (911-ish &amp;amp; transponder out), it is also an indication that somebody on the ground is aware and cares if communications are cut off and passengers do not know what is going on.  They may not be able to do anything and passengers may realize that, but at least you know the ground is aware and you aren't alone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as an on board nut-job being aware of any possible &quot;trouble&quot; he/she may get into, I think they usually don't care if they are 911 fodder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I heard that a second plane hit on 911, on the way to work, I knew life (mostly @ airports) had changed right then.&lt;/p&gt;&#xA;" OwnerUserId="6972" LastEditorUserId="1467" LastEditDate="2015-01-26T08:39:44.940" LastActivityDate="2015-01-26T08:39:44.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12026" PostTypeId="1" AcceptedAnswerId="12028" CreationDate="2015-01-26T04:01:55.213" Score="15" ViewCount="4412" Body="&lt;p&gt;I was at the Museum of Flight in Seattle, WA, yesterday, and came across a Blue Angel aircraft, pictured below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ne16K.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ne16Km.jpg&quot; alt=&quot;The Blue Angel jet as seen at the exhibit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along the right front of the plane, there is a small tube that is capped with a silver cap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kRSwLm.png&quot; alt=&quot;The tube on the side of the jet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought at first that this might be a refuelling point, but (A) I didn't see any real purpose to have mid-air refuelling on a Blue Angel, and (B) it doesn't seem like a great place to refuel (since it seems like it could easily obstruct the pilot's view).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(I looked online at some images of Blue Angel aircraft and realized there are several makes. However, I didn't find this particular tube and cap on any of the other makes. &lt;a href=&quot;http://redboxpictures.com/commercial/wp-content/uploads/2011/02/seafair_blue_angels_seattle-web-portfolio.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;(example)&lt;/a&gt; In fact, I don't even recall what make of Blue Angel this craft actually is.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this tube at the front of the jet, and what is it used for? Why does it only appear on some makes of the jet?&lt;/p&gt;&#xA;" OwnerUserId="6988" LastActivityDate="2016-12-19T20:38:38.733" Title="What is this tube along the right side of a Blue Angel?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12027" PostTypeId="2" ParentId="12026" CreationDate="2015-01-26T04:19:29.823" Score="16" Body="&lt;p&gt;It's a refueling probe. Below is a picture of it in action:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0LdYk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0LdYk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="5707" LastEditorUserId="65" LastEditDate="2015-01-26T14:43:06.350" LastActivityDate="2015-01-26T14:43:06.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12028" PostTypeId="2" ParentId="12026" CreationDate="2015-01-26T04:21:02.123" Score="25" Body="&lt;p&gt;The aircraft is the A4 Skyhawk and the probe is for air-to-air refueling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kBGjL.jpg&quot; alt=&quot;A-4 refueling from KC-10, Navy photo&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, it doesn't really impede the pilot's view which in any case, is concentrated on the refueller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can always spot a refuelling probe. For NATO aircraft, and most others, they always have the same tip and are the only appendages which look like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Blue Angels used it since transits to various air shows exceeded the range and air-air refuelling is cheaper and more effective than landing, refuelling and taking off again.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-04-15T15:59:23.360" LastActivityDate="2015-04-15T15:59:23.360" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12029" PostTypeId="2" ParentId="12015" CreationDate="2015-01-26T04:44:21.333" Score="7" Body="&lt;p&gt;I don't understand your statement &lt;code&gt;since the lifting surface is rotating around the aircraft&lt;/code&gt; - not sure where you are going with that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the principles are the same as for fixed wing.  If the CofG limits are exceeded, it is possible to run out of control authority to the extent that the aircraft becomes uncontrollable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many helicopters, I believe any with a tail rotor, have different left/right CofG limits.  The tail rotor opposes the rotation of the fuselage due to torque from the rotor.  Since it does this by producing thrust to the side, there is a &quot;translating tendency&quot; which would cause the helicopter to drift in the direction in which the TR is generating lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To counter this, the cyclic neutral position is rigged to the left (CCW rotor) or right (CW rotor) which results in the skid on that side hanging low.  Clearly, there is now less possible movement in the cyclic to that side and therefore, a narrower lateral CofG.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in a helicopter with a counter-clockwise rotating rotor, the fuselage wants to rotate clockwise.  The tail rotor will produce a thrust to the left to counter this and a long lever couple is formed with the main rotor which, if not corrected, would cause the helicopter to drift to the right.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a perfectly balanced helicopter, in a no wind steady hover, you want the cyclic to be in the centre with no force required from the pilot.  To stop the drift to the right, the cyclic is moved to the left.  To prevent the need for the pilot to do this, the cyclic is rigged so that its neutral position is to the left.  The main rotor thrust vector is now titled to the left which introduces a horizontal component of thrust acting to the left.  This also causes the left skid to hang low.  This is why in most CCW rotor helicopters, the captain sits on the right and in some of these helicopters, solo flight from the left is prohibited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the cyclic is already left of centre, there is less cyclic authority to the left than to the right.  Therefore, the right limit of lateral CofG is less than the left limit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This could not be achieved by moving the CofG since this would level the fuselage but would not oppose the thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will never forget the sensation of my first solo lift into the hover after the talking ballast (my instructor) got out and left me to it.  I lifted with the control positions where I was used to them.  Because there was 170lbs less weight in the front left corner, this meant that I started to pitch up and move back.  I was surprised by how much forward and left I had to move the cyclic to counter it.  It felt very odd for a few minutes.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1467" LastEditDate="2015-01-26T14:52:04.160" LastActivityDate="2015-01-26T14:52:04.160" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12030" PostTypeId="1" CreationDate="2015-01-26T05:28:47.753" Score="7" ViewCount="1370" Body="&lt;p&gt;For reference, I fly a Cessna 172.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read about a couple of different strategies for the impossible turn (attempting to turn back to the airport after engine failure at low altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first strategy is the one I've heard most commonly on aviation websites and videos: that is, essentially, maintain a best glide and try to make the turn as quickly as possible without stalling.  Unfortunately, a slow turn also means you'll have to turn a little more than 180 degrees to get back to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second strategy I've heard is not generally mentioned in the typical safety videos (at least that I've seen). A former flight instructor had mentioned that you could complete the impossible turn by pushing the nose down and using the additional airspeed and downward angle to execute an extremely sharp turn that would keep you closer to the runway; when you come out of the turn, you won't have to worry as much about lining back up with the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strategy 2 is clearly more risky, at least for someone who has not practiced the maneuver, so that could explain why I don't see it mentioned in most safety videos. I was wondering if anyone here had an opinion on either maneuver (or other options) for executing the impossible turn and, if possible, links to literature explaining it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance.&lt;/p&gt;&#xA;" OwnerUserId="6989" LastEditorUserId="1696" LastEditDate="2015-01-27T16:13:51.580" LastActivityDate="2015-01-27T16:13:51.580" Title="What are good strategies for the &quot;impossible turn&quot;?" Tags="&lt;general-aviation&gt;&lt;cessna-172&gt;&lt;maneuver&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2017-05-08T23:30:14.283" ContentLicense="CC BY-SA 3.0" />
  <row Id="12031" PostTypeId="1" AcceptedAnswerId="12032" CreationDate="2015-01-26T06:00:55.807" Score="5" ViewCount="2123" Body="&lt;p&gt;Recently heard the phrase &quot;traffic in position...&quot; issued by controller to one of the pilots, just wondering, what could it mean?&lt;/p&gt;&#xA;" OwnerUserId="1054" LastActivityDate="2015-01-26T18:45:20.890" Title="What does &quot;traffic in position...&quot; phrase mean?" Tags="&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12032" PostTypeId="2" ParentId="12031" CreationDate="2015-01-26T06:18:43.000" Score="5" Body="&lt;p&gt;&quot;Traffic in position&quot; is a phrase to let the next aircraft inbound to a runway know that another aircraft is in lined up and waiting for departure on that runway. This procedure is used to line an aircraft up on the runway (usually right after the previous arrival crosses the runway threshold, or previous departure begins their takeoff roll), to have them ready to go, when the previous arrival/departure clears the runway. At airports (in the US), without ASDE-X (a system to track airplanes on the ground), the tower controller isn't supposed to clear the next aircraft to land, until they have issued the takeoff clearance to the aircraft holding on the runway. ASDE-X locations can clear aircraft to land, as long as certain conditions in the ASDE-X equipment are working properly.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="1696" LastEditDate="2015-01-26T15:32:11.750" LastActivityDate="2015-01-26T15:32:11.750" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12033" PostTypeId="2" ParentId="12030" CreationDate="2015-01-26T06:20:21.377" Score="3" Body="&lt;p&gt;The already linked question has a link to &lt;a href=&quot;http://www.nar-associates.com/technical-flying/impossible/possible.html&quot; rel=&quot;nofollow&quot;&gt;this study&lt;/a&gt;. Its authors seem to have done the calculations and concluded that turn with 45° bank flown on the edge of stall lets you do it with smallest loss of altitude. Which is the point here. Don't forget you still need to glide back to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As rbp mentions below, flying the turn at edge of stall is extremely dangerous, so in practice you should plan turning around only from altitude from which the turn can be made with limit above stall (and don't forget in 45° bank the stall speed is ~20% higher and quickly increases with more bank) you are confident you can manage to maintain. This increases the altitude above which you should only attempt it but the optimal bank angle remain 45°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you used higher bank angle, you'd have to fly faster so you'd still have enough vertical lift to balance your weight. That would mean you'd need more lateral lift (even for the same turn rate the lateral acceleration is proportional to speed) to complete the turn and this lift would come with it's additional induced drag. Drag equals energy loss and the only energy you have at that point is potential energy due to altitude. So such turn would spit you out lower, which is the last thing you need. And note, that this is exactly your second option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note, that due to reasons mentioned by rbp below your margin between stall warning and severe stall is even lower in higher bank, so that's another reason against that option.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="755" LastEditDate="2015-01-26T19:18:53.657" LastActivityDate="2015-01-26T19:18:53.657" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12035" PostTypeId="2" ParentId="11969" CreationDate="2015-01-26T09:11:03.213" Score="1" Body="&lt;p&gt;The only way to increase by-pass ratio is to accelerate the high pressure turbine and avoid energy degradation.&#xA;To accelerate the high pressure turbine you need higher higher pressure and higher temperature.&#xA;A jet engine work like this :&#xA;Imagine this : the air have these values (these values are totally arbirtary) 1, 15, 200 (Pressure, temperature, speed), the jet engine Increase pressure in compressor (10, 5, 10) after this the flow pass in combustion chamber (10, 300, 10) with the turbine you transform temperature and pressure into speed (1, 20, 2000) and you pick some energy to rotate the fan.&#xA;The fan increase air speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you can increase temperature but all the parts are in metal it's why the manufacturers develop specific alloys and use ceramic foils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other thinks to do is avoid leak, the manufacturer develop new abradable material to avoid pressure leak.&#xA;The technology venture to reduce mechanical leak during energy transmission to the fan blade. &#xA;The new blades profiles (fan blades are twisted) reduce energy leak due to friction and avoid air stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the next year we will see new engine with open rotor and certainly new temperature resistant materials, thus the by-pass ratio will increase (the predictions are 30 or 40).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For open rotor and by-pass ratio see &lt;a href=&quot;http://www.aerorecherchecorac.com/article/innovation-technologies/7-demonstrateurs-pour-l-avenir-de-l-aeronautique.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; (sorry i don't have english source)&lt;/p&gt;&#xA;" OwnerUserId="3039" LastActivityDate="2015-01-26T09:11:03.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12036" PostTypeId="2" ParentId="7922" CreationDate="2015-01-26T09:28:45.793" Score="8" Body="&lt;p&gt;The utility of sending fighter jets is to destroy the plane before an hypothetical attempt. It's unfortunate, but the point is to kill a few people to save many. This can also possibly have the impact of scaring the hijacker/terrorist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the mean time, someone in the ATC can attempt to negotiate with the terrorist before any shoot-downs are needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In France, we send two fighter jets, because one jet is there to make contact with the pilot (seated on the left of the cockpit) while the other fighter stays behind the aircraft ready fire if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only person allowed to make the decision to fire, is the Prime Minister.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, fighter jets take off on these missions quite often, but it's usually only for providing assistance (e.g. providing landing clearance to an aircraft with dead radio).&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="2171" LastEditDate="2015-01-26T15:04:08.763" LastActivityDate="2015-01-26T15:04:08.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12038" PostTypeId="1" AcceptedAnswerId="12039" CreationDate="2015-01-26T15:18:20.023" Score="4" ViewCount="1615" Body="&lt;p&gt;Based on &lt;a href=&quot;https://aviation.stackexchange.com/a/12008/3775&quot;&gt;this other answer&lt;/a&gt;, a new question arose.&#xA;When is runway slope most important, at take-off or at landing? Or is it equally important in both flight phases? &lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-01-27T01:04:55.807" Title="When is runway slope most important?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12039" PostTypeId="2" ParentId="12038" CreationDate="2015-01-26T15:26:05.077" Score="4" Body="&lt;p&gt;I would argue that it is most important on takeoff. The reason is that most planes require more distance for takeoff than for landing (partially due to higher weight). Also, it is generally easier to abort a takeoff than a landing (when on the ground at least).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both landing and takeoff distance calculations are performed (which should take slope into account) to ensure that there is sufficient distance for the aircraft. However, in addition to aborting a takeoff being easier, more can go wrong in a landing. Windshear or improper approach settings can cause an airplane to touch down later or faster, which risks an overrun. During takeoff, the plane has until V1 (takeoff decision speed) to abort if any issues arise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this certainly depends on conditions. Aircraft condition, wind and runway surface condition can increase the distance needed for landing (or aborting a takeoff). If reverse thrust is not available, there is a tailwind, and the runway is wet, that could change the situation.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-26T17:18:28.533" LastActivityDate="2015-01-26T17:18:28.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12040" PostTypeId="2" ParentId="12038" CreationDate="2015-01-26T15:59:43.957" Score="1" Body="&lt;p&gt;The only time you would worry about runway slope is insufficient runway. So let's consider a runway overrun:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On takeoff, there's a period where you should no longer abort takeoff, as there is likely insufficient room for stopping. That happens as the plane accelerates pass V1. At that point the aircraft is quite some way down the runway travelling fast. It's heavy as well. If a late rejected take off is initiated, you'll likely hit the fence at a very high speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On landing, you plan to stop the plane anyway. If things go awry, you can always step on the brakes. Landing distances are never computed at max braking so you got some room. If you overrun, you'll hit at a much slower speed, since the plane is slowing down in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore I'd argue it is more important on takeoff.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-26T15:59:43.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12041" PostTypeId="2" ParentId="12038" CreationDate="2015-01-26T16:26:57.947" Score="3" Body="&lt;p&gt;I would rather land downhill than takeoff uphill because taking off uphill you have just one thing to get you off the ground: thrust (ok, maybe a little flaps helps in some airplanes). On landing, I have a lot of things I can control: approach speed (slow), approach angle (steep), approach power (none), flaps (full), flaring before the threshold, aerodynamic braking with the elevator, pulling the flaps, full braking. some of it is admittedly pretty gutsy, but you can stop even a slippery airplane quite quickly.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-26T16:26:57.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12043" PostTypeId="2" ParentId="12031" CreationDate="2015-01-26T16:40:55.070" Score="7" Body="&lt;p&gt;The phraseology in the question is incorrect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the planes on on the same runway without ASDE-X, the aircraft departing will be given:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DELTA 2-7, RUNWAY 1, LINE UP AND WAIT, BOEING 7-2 6-MILE FINAL&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The arriving aircraft will not be given a landing clearance until the holding aircraft has departed, but it will be told:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AMERICAN 4-2-9, RUNWAY 1, CONTINUE, TRAFFIC HOLDING IN POSITION&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the planes are on different runways, it would be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DELTA 2-7, RUNWAY 1, LINE UP AND WAIT, TRAFFIC LANDING RUNWAY 19&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and the other &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AMERICAN 4-2-9, RUNWAY 1-9, CLEARED TO LAND, TRAFFIC HOLDING IN POSTION RUNWAY 1&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;Air Traffic Conrollers Handbook, Section 3−9−4. LINE UP AND WAIT (LUAW)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-26T18:45:20.890" LastActivityDate="2015-01-26T18:45:20.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12045" PostTypeId="1" AcceptedAnswerId="12046" CreationDate="2015-01-26T19:00:41.403" Score="12" ViewCount="2855" Body="&lt;p&gt;I was reading an &lt;a href=&quot;http://avherald.com/h?article=3f7431e7/013&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;article about TAM Airlines Flight 3054 crash&lt;/a&gt; and I saw the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;METAR&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018&lt;/li&gt;&#xA;  &lt;li&gt;SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018&lt;/li&gt;&#xA;  &lt;li&gt;SBSP 172100z 34008kt 6000 -ra Bkn009 Ovc070 16/14 Q1018&lt;/li&gt;&#xA;  &lt;li&gt;SBSP 172030z 32009kt 7000 -ra Bkn013 Ovc080 16/14 Q1018&lt;/li&gt;&#xA;  &lt;li&gt;SBSP 172000z 31012kt 8000 -ra Bkn016 Ovc080 17/14 Q1018&lt;/li&gt;&#xA;  &lt;li&gt;SBSP 171900z 34009kt 9999 -ra Bkn016 Bkn080 18/15 Q1017&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is METAR?&lt;/li&gt;&#xA;&lt;li&gt;How is it read?&lt;/li&gt;&#xA;&lt;li&gt;What is the difference between the International METAR codes and the&#xA;North American METAR codes?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="1700" LastEditDate="2015-07-13T12:04:56.147" LastActivityDate="2015-07-13T12:04:56.147" Title="What is METAR and how is it read?" Tags="&lt;airport&gt;&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12046" PostTypeId="2" ParentId="12045" CreationDate="2015-01-26T19:05:59.867" Score="16" Body="&lt;p&gt;METAR is a Meteorological Aerodrome Report which is for a specific place, at a specific time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first line is a report from Sao Paulo at 22:00 on the 17th.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use a service such as &lt;a href=&quot;http://www.wx-now.com/Weather/MetarDecode&quot; rel=&quot;nofollow&quot;&gt;this one&lt;/a&gt; to decode METAR reports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest of the lines are more reports for different time and days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The groups are:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; SBSP       Reporting station ICAO code&#xA; 172220Z    Day of the month (17) and current time in UTC (2220) (Z for Zulu time)&#xA; 35008KT    Wind from 350 degrees true at 8 knots&#xA; 7000       Horizontal visibility on the ground in metres&#xA; -RA        Current weather (RA = rain), the minus indicates light, plus indicates heavy&#xA; BKN008     Broken clouds at 800 feet&#xA; OVC070     Overcast clouds at 7000 feet&#xA; 15/14      Temperature 15C, dew-point 14C&#xA; Q1018      regional atmospheric pressure 1018hPa / US systems use inHG / others use millibars&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-01-27T07:55:45.997" LastActivityDate="2015-01-27T07:55:45.997" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12047" PostTypeId="2" ParentId="12038" CreationDate="2015-01-26T23:48:34.040" Score="2" Body="&lt;p&gt;I am going to introduce another perspective. We are talking about a road of 3km length with a potential difference of 1% (30m!!!!) between the highest and lowest place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runaways are always thought to have enough visibility for the pilot when trying to land of take-off. Limitations of the slope in airports are not related to performance of the airplane, instead is a safety and visibility constrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, either I am taking off or I am landing I prefer in both to be running uphill where my airplane at the fastest speeds, so I will be able to see any object really far from where I am. No matter the performance I lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice, that we need to consider also the visual range of the pilot (which is several meters above the road) which is not 3km for small objects, but, I prefer the safest condition: Uphill.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-01-26T23:48:34.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12048" PostTypeId="1" AcceptedAnswerId="12057" CreationDate="2015-01-27T01:44:11.013" Score="20" ViewCount="5155" Body="&lt;p&gt;In &lt;a href=&quot;http://www.avweb.com/avwebflash/news/Two-Airplanes-Successfully-Ditch-In-Pacific223452-1.html&quot; rel=&quot;noreferrer&quot;&gt;this incident near Hawaii&lt;/a&gt;, a Cirrus SR22 had fuel problems and deployed its &lt;a href=&quot;http://en.wikipedia.org/wiki/Ballistic_Recovery_Systems#Cirrus_Airframe_Parachute_System_.28CAPS.29&quot; rel=&quot;noreferrer&quot;&gt;airframe parachute&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is why did the pilot deploy the parachute rather than perform a &quot;normal&quot; ditching procedure in the ocean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, here's &lt;a href=&quot;http://youtu.be/TmUYSztQyqo&quot; rel=&quot;noreferrer&quot;&gt;the video&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="182" LastEditDate="2015-03-10T23:51:52.203" LastActivityDate="2015-03-10T23:51:52.203" Title="Why did this Cirrus deploy the parachute while ditching over Pacific Ocean?" Tags="&lt;emergency&gt;&lt;ditching&gt;&lt;airframe-parachute&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12049" PostTypeId="2" ParentId="12048" CreationDate="2015-01-27T02:02:28.867" Score="9" Body="&lt;p&gt;Maybe pulling the chute &lt;em&gt;is&lt;/em&gt; the normal ditching procedure for a cirrus with an airframe chute. The splash down looks to be very gentle compared to a normal gliding ditch with fixed gear. It's also less prone to pilot error; once you are dangling there is not much the pilot can mess up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine the checklist being something like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;pull chute&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;when aircraft stabilizes open door put on life vest and prepare raft&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;should plane roll and sink get out and on the raft&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-27T08:40:54.273" LastActivityDate="2015-01-27T08:40:54.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12050" PostTypeId="2" ParentId="11260" CreationDate="2015-01-27T03:49:43.427" Score="6" Body="&lt;p&gt;In general, unmanned flight control systems operate in one of two main modes: &lt;em&gt;manual control&lt;/em&gt; and &lt;em&gt;program&lt;/em&gt;.  (There are other modes but these are typically specific situations, such as launch/landing sequences, loss of link (aka &quot;return home&quot;), and any other design-specific operating modes as required (see below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question, if link is lost while the aircraft is in manual operation, a good flight system will automatically go into &quot;return home&quot; mode, where it flies to a pre-programmed GPS coordinate and altitude.  Some software will allow you to customize the sequence, such as whether or not to spiral up to altitude before heading to that coordinate.  Other software will backtrace the route it took.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft following a pre-programmed route typically change to manual mode upon completion, hoping there's a good ground link at the other end.  In military operations, this is known as a &quot;hand-off&quot; where one ground station takes control from another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One Shadow flight I was running lost link immediately after launch.  After completing its autolaunch sequence, it went to return home and circled for hours until it ran out of fuel, at which point the engine stalled and the generator (alternator) hiccuped in transition to battery power, causing the flight processor to reboot, at which point we re-acquired link, though too late to do anything about it.  The UAV had already noticed its engine wasn't spinning and initiated its ditch sequence, rolling over and popping the chute.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-01-27T03:49:43.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12053" PostTypeId="2" ParentId="12048" CreationDate="2015-01-27T09:40:12.693" Score="33" Body="&lt;p&gt;Once your engine fails the airplane is the property of the insurance company, your only goal at that point should be to survive. Using a whole-airframe chute increases your chances of survival whether over land or sea. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The things that kill people in forced landings of any kind are high-g deceleration and post crash fire. A parachute decreases the chances of both as you have very low lateral speed and much less chance of fuel tank leaks. A parachute also will increase the chance the airplane will remain upright, so escaping the aircraft will be much easier - very important in a water landing!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason for a &quot;normal&quot; ditching procedure is that you have no other choice, using a parachute if you have one will almost always be the right option. The only time I would consider otherwise is if I had enough altitude to glide to a safer emergency landing spot. If pulling the chute would mean landing in water or dangerous terrain but gliding would mean reaching land where a forced landing was reasonable I'd probably opt for gliding.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-01-27T09:40:12.693" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12054" PostTypeId="1" AcceptedAnswerId="16477" CreationDate="2015-01-27T10:19:27.847" Score="8" ViewCount="1126" Body="&lt;p&gt;I was scanning the local aviation radio frequencies, and came across an odd signal (listen to a recording &lt;a href=&quot;https://onedrive.live.com/redir?resid=2E06CD9BA226BCE0%2114410&quot;&gt;here&lt;/a&gt;).&#xA;It's at around 110.515MHz, and it seems strong within a 30 mile radius of Shropshire, UK (haven't tried tuning in further afield).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure if it's relevant, but there are a couple of RAF bases nearby (RAF Shawbury and RAF Cosford).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume it's a navigation aid, but couldn't find anything listed on that frequency.&#xA;I was hoping someone would recognise the sound and be able to tell me what equipment is transmitting it (e.g. NDB).&lt;/p&gt;&#xA;" OwnerUserId="7000" LastEditorUserId="19" LastEditDate="2015-01-27T10:22:59.107" LastActivityDate="2015-07-01T07:42:59.270" Title="What is transmitting this radio signal @~110.515MHz and for what purpose?" Tags="&lt;radio&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12055" PostTypeId="1" CreationDate="2015-01-27T12:50:50.793" Score="13" ViewCount="1688" Body="&lt;p&gt;Why isn't it possible to locate the rudder in front of an airplane's center of gravity?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically how does this relate to the stability derivative?&lt;/p&gt;&#xA;" OwnerUserId="7002" LastEditorUserId="19" LastEditDate="2015-01-27T20:28:51.983" LastActivityDate="2018-05-25T22:34:22.893" Title="Why isn't it possible to locate the rudder in front of an airplane's center of gravity?" Tags="&lt;aircraft-design&gt;&lt;rudder&gt;&lt;stability&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12056" PostTypeId="1" AcceptedAnswerId="12059" CreationDate="2015-01-27T14:57:44.973" Score="8" ViewCount="3054" Body="&lt;p&gt;I've been in the very early stages of shopping for my first single engine plane. That has made me more thoughtful about the environment in which a given plane is stored. So the recent blizzard in the Northeast has had me asking some &quot;what-ifs&quot; from a perspective buyer's point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Boston area, there are forecasts for 15-25 inches of snow. If a typical GA plane (e.g. a C172) is tied down in those conditions, is the weight of that much snow on the wings sufficient to cause any permanent deformation or other issues? Are there things you would instruct your pre-buy inspector to pay extra close attention to knowing the plane had been through such an extreme event?&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="3504" LastEditDate="2015-01-28T16:07:09.770" LastActivityDate="2017-12-05T14:32:24.257" Title="How well can an airplane which is tied down be protected from a blizzard?" Tags="&lt;general-aviation&gt;&lt;weather&gt;&lt;aircraft-storing&gt;&lt;airframe&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12057" PostTypeId="2" ParentId="12048" CreationDate="2015-01-27T14:58:49.743" Score="33" Body="&lt;p&gt;First, according to one &lt;a href=&quot;http://nebula.wsimg.com/1e1b78d6b9689ed47e52182f797a6c4e?AccessKeyId=3E8FEAF15ED124417DD9&amp;amp;disposition=0&amp;amp;alloworigin=1&quot;&gt;operating handbook&lt;/a&gt; for the Cirrus SR-22 (there are several versions out there), pulling the chute &lt;em&gt;is&lt;/em&gt; the correct ditching procedure (CAPS is the parachute system):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ditching&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Radio ............................................ Transmit (121.5 MHz) MAYDAY giving location and intentions&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Transponder...........................................................&#xA;  SQUAWK 7700&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;CAPS .............................................................................&#xA;  ACTIVATE&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Airplane.........................................................................EVACUATE&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Flotation Devices ............INFLATE WHEN CLEAR OF AIRPLANE&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Second, the conditions were &lt;a href=&quot;http://www.hawaii247.com/2015/01/25/plane-northeast-of-big-island-prepares-to-ditch-in-ocean-sunday-jan-25/&quot;&gt;reported&lt;/a&gt; to be windy with high waves:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Weather conditions at the time of the rescue were seas of 9 to 12 feet&#xA;  and winds of 25 to 28 mph.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Those would be tough conditions for ditching in. I've read several times that when light aircraft ditch, the pilot and passengers usually survive the impact but they often struggle to exit the aircraft successfully. &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/June/20/staying-alive-survival-training-for-after-a-ditching.aspx&quot;&gt;This article&lt;/a&gt; and &lt;a href=&quot;http://www.aopa.org/AOPA-Live.aspx?watch=%7B809D9C7A-4A16-47A7-8D75-E4BF857D216C%7D&quot;&gt;video&lt;/a&gt; explain in detail how difficult it can be to exit an aircraft in the water, even in good conditions. If the aircraft flips or cartwheels then exiting would be extremely tough and the rough sea would make it much worse. Since the parachute lowers the aircraft straight down in a more or less level attitude, the chance of flipping over is greatly reduced. The downside is that you no longer have control of where you touch down relative to the waves, so you might land just in front of one but that still seems like a good option compared to the risk of flipping the aircraft on impact.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-01-27T14:58:49.743" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12058" PostTypeId="2" ParentId="11260" CreationDate="2015-01-27T15:31:27.920" Score="5" Body="&lt;p&gt;From a technical standpoint, as other answers pointed out, it is technically feasible. For instance, universities have attempted a &lt;a href=&quot;http://wiki.paparazziuav.org/wiki/Corsica&quot;&gt;180 km flight over the Mediterranean sea&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are also legal issues involved when flying a drone beyond the range of the remote control device. For instance, in &lt;a href=&quot;http://www.legifrance.gouv.fr/affichTexte.do;jsessionid=?cidTexte=JORFTEXT000025834953&amp;amp;dateTexte=&amp;amp;oldAction=rechJO&amp;amp;categorieLien=id&quot;&gt;France&lt;/a&gt;, even when using an autopilot to control a drone, a safety pilot must stand ready to take control of the drone in case anything happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Chicago Convention (1944), article 8 states that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No aircraft capable of being flown without a pilot shall be flown without a pilot&#xA;  over the territory of a contracting State without special authorization by that&#xA;  State and in accordance with the terms of such authorization. Each contracting&#xA;  State undertakes to insure that the flight of such aircraft without a pilot in&#xA;  regions open to civil aircraft shall be so controlled as to obviate danger to civil&#xA;  aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In many countries, these special authorizations can take a few months (a little more than three months in the case of the 180 km flight over the Mediterranean sea) to obtain, so hobbyists usually don't bother. &lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-01-27T15:31:27.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12059" PostTypeId="2" ParentId="12056" CreationDate="2015-01-27T15:59:10.903" Score="5" Body="&lt;p&gt;There are several additional measures which can be done to prevent a tied down airplane from harsh weather, storms and blizzards. However, nature is always more powerful than humans and  it can overcome any safety measures taken by them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your airplane is tied down properly and securely, hail is a bigger threat than storms or blizzards. A hangar protects an airplane more than the one outside, but it costs a lot more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.experimentalaircraft.info/flight-planning/aviation-hazards-5.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; (and &lt;a href=&quot;http://www.experimentalaircraft.info/flight-planning/aviation-hazards-6.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;page 2&lt;/a&gt;) discusses several measures you can take to protect your airplane against harsh weather. To avoid redundancy, I am just pointing (and paraphrasing) a few here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Parking spot&lt;/strong&gt;&lt;br/&gt;&#xA;  If you can, choose a spot which can break the wind intensity.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Anchor points&lt;/strong&gt;&lt;br/&gt;&#xA;  Depending on the aircraft, the anchor points' holding strength must be 3000-4000 lbs.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Ropes&lt;/strong&gt;&lt;br/&gt;&#xA;  You should use those ropes which do not shrink when wet (e.g., nylon or dracon ropes instead of Manila).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Position&lt;/strong&gt;&lt;br/&gt;&#xA;  If possible, park aircraft nearly into the wind as possible.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Weight&lt;/strong&gt;&lt;br/&gt;&#xA;  A lighter object is easier to get displaced. You can fill-up the tanks to add extra weight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you interested in reading some long articles, &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2004/October/200410_Features_Tying_the_knot.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/tie_down.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; provide some useful information too.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding your second question about snow on the wings, I hardly doubt that something like this will happen:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CtYjy.jpg&quot; alt=&quot;Cessna 172 Wings&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above &lt;a href=&quot;http://www.berkut13.com/berkut60.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;happened&lt;/a&gt; because:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... when the tail hook was torn off and the plane was pushed forward, breaking the spar. &lt;em&gt;&lt;a href=&quot;http://www.berkut13.com/fltops08/storm09.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;(picture here)&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airplane wings are very sturdy. They can bear the weight of a foot or two of snow.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2017-12-05T14:32:24.257" LastActivityDate="2017-12-05T14:32:24.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12060" PostTypeId="2" ParentId="11260" CreationDate="2015-01-27T16:18:36.967" Score="4" Body="&lt;p&gt;From a technical perspective, there's nothing preventing it. It wouldn't even be very difficult to write the code to do it if you had a GPS receiver on board, especially if you also had accelerometers to interpolate position between GPS fixes. For that matter, remote control via a cellular network wouldn't be particularly complicated from a technical implementation perspective (and this would also aid in navigation if you triangulate position from the towers.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the problem comes in is legal issues. Specifically, in the U.S., at least, operating such an unmanned aircraft outside the line-of-sight of the operate is illegal unless you have a special license from the FAA, which is generally only granted to federal government agencies or law enforcement/emergency/rescue organizations or to aircraft R&amp;amp;D organizations. &lt;a href=&quot;https://www.faa.gov/uas/&quot; rel=&quot;nofollow&quot;&gt;According to the FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Recreational use of airspace by model aircraft is covered by &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Advisory_Circular/91-57.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Advisory Circular 91-57 (PDF)&lt;/a&gt;, which generally limits operations for hobby and recreation to below 400 feet, away from airports and air traffic, and within sight of the operator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-01-27T16:18:36.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12061" PostTypeId="1" AcceptedAnswerId="12064" CreationDate="2015-01-27T16:23:20.247" Score="44" ViewCount="21777" Body="&lt;p&gt;Here are a couple of examples:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Iuvmm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aGR86.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-01-29T22:27:27.483" Title="Why did most airliners have black noses in the 60's and 70's?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12062" PostTypeId="2" ParentId="12061" CreationDate="2015-01-27T16:47:00.803" Score="11" Body="&lt;p&gt;It is called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Nose_cone#Aircraft&quot;&gt;nose cone&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There can a several reasons (as mentioned &lt;a href=&quot;http://boards.straightdope.com/sdmb/showthread.php?t=245564&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20090708203119AAw62n7&quot;&gt;here&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Aircraft used to be painted with a lead-based paint, which is unsuitable for radomes. Instead, they had a rubber coating. Nowadays,&#xA;  the paint used (epoxy on military planes, I believe) won't affect the&#xA;  radar.&lt;/li&gt;&#xA;  &lt;li&gt;It's as much a fashion statement as anything else&lt;/li&gt;&#xA;  &lt;li&gt;It started out as an anti-glare panel. The fuselage within pilot's view is painted dark and of matte finish to reduce the chance of any&#xA;  glare that might obscure pilot's vision.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even today, you can find some military aircraft with a darker nose cone.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-01-27T16:47:00.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12063" PostTypeId="2" ParentId="12061" CreationDate="2015-01-27T16:50:00.790" Score="28" Body="&lt;p&gt;Because the nose of the plane is where the weather radar antenna is, and paint would interfere with the signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not just the 60's and 70's, and its not only on the nose. Here's a brand new PC-12 with a radar dome (radome) on the right wing, painted black:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DbeXJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside of the radome is a radar array that can be tilted and panned using a control inside the cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LlEKq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the pilot's view inside the cockpit, which shows the knobs used to adjust the pan/tilt, range, and sensitivity:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/myvLM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And you can read a brochure about a particular aviation radar system &lt;a href=&quot;http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/BA_brochures-documents/RDR_2000_and_2100_Weather_Radar.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-28T13:47:01.387" LastActivityDate="2015-01-28T13:47:01.387" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12064" PostTypeId="2" ParentId="12061" CreationDate="2015-01-27T16:50:15.747" Score="40" Body="&lt;p&gt;Under the nose of modern airliners is weather radar that helps the crew to see and avoid hazardous weather conditions. This is required by &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol3/xml/CFR-2011-title14-vol3-sec121-357.xml&quot;&gt;FAA CFR §121.357&lt;/a&gt; for transport category aircraft. The radar signal would be blocked by the aluminum that makes up the rest of the fuselage, so the radome is made of a non-metallic material, generally a fiberglass composite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/65775/&quot;&gt;These&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/528830/&quot;&gt;threads&lt;/a&gt; discuss the topic. The last post in the first linked thread suggests that most paint needed lead to prevent fading and/or a zinc-based primer, which would interfere with the radar. Black was one color that did not require these. Modern paint has done away with these metal additives, allowing more color options without interfering with the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.museumofflight.org/faq/why-tip-747%E2%80%99s-nose-black&quot;&gt;The Museum of Flight&lt;/a&gt; claims that the black color is only to remind crews to not paint over the radome. Painting over it would affect the radar signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://boards.straightdope.com/sdmb/showthread.php?t=245564&quot;&gt;According to this thread&lt;/a&gt;, the color of the radome affects the operation of the weather radar underneath. They were painted black because it has the lowest reflectivity. Modern radars are able to deal with different colors much better.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-29T22:27:27.483" LastActivityDate="2015-01-29T22:27:27.483" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12065" PostTypeId="2" ParentId="1017" CreationDate="2015-01-27T18:05:22.583" Score="-1" Body="&lt;p&gt;&lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/135.329&quot; rel=&quot;nofollow&quot;&gt;14 CFR 135.329 (e)(1)&lt;/a&gt; states that crew members are to be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... adequately trained and currently proficient for each aircraft,&#xA;  crewmember position, and type of operation in which the crewmember&#xA;  serves&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which would indicate to me that the S.I.C. also needs a 135.293 ride in left seat which would also include an ILS to minimum as well as a non-precision approach.  &lt;/p&gt;&#xA;" OwnerUserId="7003" LastEditorUserId="65" LastEditDate="2015-01-27T18:25:14.353" LastActivityDate="2015-01-27T18:25:14.353" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12066" PostTypeId="2" ParentId="12048" CreationDate="2015-01-27T18:12:31.800" Score="5" Body="&lt;p&gt;The odds of survival with the chute are currently at 100% (Per Cirrus) and the odds of surviving a ditching are much less. The plane was lost in the Pacific either way.  The correct thing to do is pull the lever and ride it down, live to be a great pilot another day.  The real question is what did the pilot do wrong to end up in that situation?&lt;/p&gt;&#xA;" OwnerUserId="7004" LastActivityDate="2015-01-27T18:12:31.800" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12067" PostTypeId="1" CreationDate="2015-01-27T19:57:04.940" Score="8" ViewCount="2750" Body="&lt;p&gt;I am a cargo aircraft loader at Heathrow and while we were offloading cargo, pallets and baggage containers from a Pakistan Airlines B777, the aircraft's &lt;a href=&quot;http://en.wikipedia.org/wiki/Auxiliary_power_unit&quot;&gt;Auxiliary Power Unit&lt;/a&gt; (APU) failed. It made matters worse when we attached the &lt;a href=&quot;http://en.wikipedia.org/wiki/Shorepower#Aircraft&quot;&gt;Ground Power Unit&lt;/a&gt; (GPU) ground cables to the aircraft nose because the GPU went into trip mode. This resulted in a complete loss of power and we were unable to open up the front and rear cargo doors. The loading systems' Power Drive Unit (PDU) also failed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My team leader played with the GPU leads and set them at a certain angle where the trip mode stopped and we offloaded the airplane. What could cause this APU failure, and why would the GPU trip? Is this a safety issue if airlines operate a non-functional APU on their aircraft?&lt;/p&gt;&#xA;" OwnerUserId="7005" LastEditorUserId="62" LastEditDate="2015-01-27T20:34:08.787" LastActivityDate="2015-01-27T20:46:13.387" Title="What could cause the APU on a Boeing 777 to fail and also trip the GPU?" Tags="&lt;ground-operations&gt;&lt;apu&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12068" PostTypeId="5" CreationDate="2015-01-27T20:05:31.140" Score="0" Body="&lt;p&gt;&lt;strong&gt;VTOL&lt;/strong&gt; (&lt;strong&gt;V&lt;/strong&gt;ertical &lt;strong&gt;T&lt;/strong&gt;ake&lt;strong&gt;O&lt;/strong&gt;ff and &lt;strong&gt;L&lt;/strong&gt;anding) describes aircraft that can, as the name indicates, perform &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt;s and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt;s vertically. Similar acronyms include &lt;a href=&quot;/questions/tagged/stol&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stol&amp;#39;&quot; rel=&quot;tag&quot;&gt;stol&lt;/a&gt; (&lt;strong&gt;S&lt;/strong&gt;hort &lt;strong&gt;T&lt;/strong&gt;ake&lt;strong&gt;O&lt;/strong&gt;ff and &lt;strong&gt;L&lt;/strong&gt;anding), V/STOL (&lt;strong&gt;V&lt;/strong&gt;ertical/&lt;strong&gt;S&lt;/strong&gt;hort &lt;strong&gt;T&lt;/strong&gt;ake&lt;strong&gt;O&lt;/strong&gt;ff and &lt;strong&gt;L&lt;/strong&gt;anding), STOVL (&lt;strong&gt;S&lt;/strong&gt;hort &lt;strong&gt;T&lt;/strong&gt;ake&lt;strong&gt;O&lt;/strong&gt;ff and &lt;strong&gt;V&lt;/strong&gt;ertical &lt;strong&gt;L&lt;/strong&gt;anding), and V/STOVL (&lt;strong&gt;V&lt;/strong&gt;ertical/&lt;strong&gt;S&lt;/strong&gt;hort &lt;strong&gt;T&lt;/strong&gt;ake&lt;strong&gt;O&lt;/strong&gt;ff and &lt;strong&gt;V&lt;/strong&gt;ertical &lt;strong&gt;L&lt;/strong&gt;anding).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three main ways an aircraft can take off and/or land vertically:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Using rotating wings (i.e., being a &lt;a href=&quot;/questions/tagged/rotorcraft&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rotorcraft&amp;#39;&quot; rel=&quot;tag&quot;&gt;rotorcraft&lt;/a&gt;), so that the wings can see high-speed airflow even when the aircraft has no horizontal movement (&lt;a href=&quot;/questions/tagged/helicopter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;helicopter&amp;#39;&quot; rel=&quot;tag&quot;&gt;helicopter&lt;/a&gt;s, &lt;a href=&quot;/questions/tagged/tiltrotor&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tiltrotor&amp;#39;&quot; rel=&quot;tag&quot;&gt;tiltrotor&lt;/a&gt;s).  Not all rotorcraft are fully VTOL-capable, however; an &lt;a href=&quot;/questions/tagged/autogyro&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;autogyro&amp;#39;&quot; rel=&quot;tag&quot;&gt;autogyro&lt;/a&gt; cannot take off vertically, as its main rotor is unpowered and relies on airflow through the rotor disk to rotate its blades (autogyros can, however, &lt;em&gt;land&lt;/em&gt; vertically).&lt;/li&gt;&#xA;&lt;li&gt;Being lighter than air, so that the aircraft floats into the air under its own buoyancy (&lt;a href=&quot;/questions/tagged/airship&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airship&amp;#39;&quot; rel=&quot;tag&quot;&gt;airship&lt;/a&gt;s, &lt;a href=&quot;/questions/tagged/balloon&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;balloon&amp;#39;&quot; rel=&quot;tag&quot;&gt;balloon&lt;/a&gt;s; these are collectively known as &lt;em&gt;aerostats&lt;/em&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Directing the thrust from a &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt; (or, occasionally, &lt;a href=&quot;/questions/tagged/rocket&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rocket&amp;#39;&quot; rel=&quot;tag&quot;&gt;rocket&lt;/a&gt;) downwards in order to push the aircraft upwards.  Most VTOL combat aircraft (popularly known as &quot;jump jets&quot;) use this method.  There are three main ways of doing this:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;em&gt;tailsitting&lt;/em&gt; aircraft sits vertically when on the ground, with its &lt;a href=&quot;/questions/tagged/tail&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tail&amp;#39;&quot; rel=&quot;tag&quot;&gt;tail&lt;/a&gt; pointing straight down.  This was tried on a number of very early VTOL aircraft, but was abandoned due to the extreme difficulty of landing an aircraft when you can't see the ground, as well as problems with transitioning between vertical and horizontal flight and the need for a ladder when entering or egressing the cockpit.&lt;/li&gt;&#xA;&lt;li&gt;Vertically-mounted auxiliary engines (known as &lt;em&gt;lift engines&lt;/em&gt; or &lt;em&gt;lift jets&lt;/em&gt;) can be used to provide vertical thrust while allowing takeoffs and landings to be made in the conventional horizontal orientation, but the extra engines used only for takeoff and landing impose a considerable weight penalty, degrading &lt;a href=&quot;/questions/tagged/aircraft-performance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-performance&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-performance&lt;/a&gt;.  As a result, this solution has only been used on a few varieties of aircraft, and usually only as a supplement to vectored thrust (see below).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/thrust-vectoring&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust-vectoring&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust-vectoring&lt;/a&gt; can be used to redirect the gas flow from a horizontally-mounted engine downwards.  This poses some engineering challenges, but allows the aircraft to take off and land vertically without needing to use heavy additional engines or sit on its tail.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has more information on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;VTOL aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rotorcraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rotorcraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aerostat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lighter-than-air aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Tail-sitter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tailsitters&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_jet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lift engines&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thrust vectoring&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-10-06T11:04:15.893" LastActivityDate="2019-10-06T11:04:15.893" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12069" PostTypeId="4" CreationDate="2015-01-27T20:05:31.140" Score="0" Body="For questions about vehicles capable of vertical take-off and landing." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-07-08T14:33:17.803" LastActivityDate="2016-07-08T14:33:17.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12070" PostTypeId="1" CreationDate="2015-01-27T20:23:22.413" Score="5" ViewCount="23247" Body="&lt;p&gt;What is a minimum equipment list for an aircraft? How are MEL and MMEL related? Who creates the list, and how do they decide what is on it?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2019-12-09T22:01:27.320" Title="What is the MEL (minimum equipment list)?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-systems&gt;&lt;equipment&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12071" PostTypeId="2" ParentId="12070" CreationDate="2015-01-27T20:32:08.850" Score="6" Body="&lt;p&gt;As &lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=4590&quot; rel=&quot;noreferrer&quot;&gt;mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A minimum equipment list is a list of equipment that must be installed&#xA;  and operable for the aircraft to be considered airworthy. It is&#xA;  aircraft-specific and spells out which pieces of equipment may be&#xA;  inoperable while maintaining airworthiness. If something is found to&#xA;  be inoperative, the pilot goes to the MEL, finds the entry for that&#xA;  item, and determines if the airplane must be grounded until that piece&#xA;  of equipment is fixed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Master_minimum_equipment_list&quot; rel=&quot;noreferrer&quot;&gt;Master minimum equipment list&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An MEL for a specific aircraft originates from a master minimum&#xA;  equipment list (MMEL). The MMEL is a list of all equipment on an&#xA;  aircraft type; it details which equipment is allowed to be inoperative&#xA;  without grounding the aircraft. (Think of a MMEL as a general, broader&#xA;  MEL.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA &lt;a href=&quot;http://fsims.faa.gov/PICResults.aspx?mode=Publication&amp;amp;doctype=MMEL&quot; rel=&quot;noreferrer&quot;&gt;publishes MMELs&lt;/a&gt; by manufactures.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-01-27T20:32:08.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12072" PostTypeId="2" ParentId="12067" CreationDate="2015-01-27T20:46:13.387" Score="8" Body="&lt;p&gt;Dispatching an aircraft with an inoperative APU, regardless of whether it's a passenger aircraft or a freighter, is a normal procedure. While an APU may be started inflight preparatory to it's use after landing, it is not needed inflight, so it's not a safety issue. In my experience (retired in 1999), dispatch of freighters with inoperative APUs is more common than dispatching passenger aircraft that way due to the passenger comfort aspect. Keeping passengers cool while unloading/loading is a priority. Keeping a freighter's crew comfortable is not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An APU failing while in use is not unusual. GPU failure is also not unusual. If the APU tripped (as opposed to just quit) and the GPU tripped as well, a natural suspect is an electrical problem in the airplane. What is needed, of course, is a competent mechanic to troubleshoot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;APUs can fail for a number of reasons. They're just small turbine engines. In fact, for 747-100 and -200 aircraft, the APUs were often the same as the engines used for SA-226 and -227 Metroliners (with the addition of propellers of course) that I flew prior to flying 747s. Common causes of APU failure include overheating, loss of oil pressure, excessive load, and just plain mechanical breakdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The decision as to whether to dispatch a large airplane without an APU would be an economic one primarily. If you're sending the airplane to an airport that is known to have GPU power, it wouldn't make financial sense to delay the flight because of an inoperative APU. If, however, you're dispatching to an airport that doesn't have such, that would be unwise unless such an airport does have a huffer and you want to risk a battery start (never a good idea in my opinion).&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-01-27T20:46:13.387" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12073" PostTypeId="2" ParentId="11155" CreationDate="2015-01-27T21:58:01.643" Score="0" Body="&lt;p&gt;Just went through the pain in having to remove the leaking right fuel tank from my 1975 C-150M during an annual inspection.  I've owned the plane 3 years. All 46 screws for the skin and cap plate were frozen and covered in several coats of paint. Tried step 1--No joy. Tried step 2 with PB Blaster--No joy. Tried step 3--Nada.  The IA had to drill out most of the screws (a few backed out using left-hand drill bits). It was a 2-day ordeal.  Also discovered one of the two retaining straps was broken and (unknown to me) inside the tank there was a half-melted plastic fuelHawk gauge, a yellowed flexible plastic gas tank filler cap and the gas cap chain.  IA suspects all have been in the tank at least a decade or more. Got the top skin back on today and finished the annual. The culprit turned out to be a leaking sending unit on top of the tank--undetectable until we got the entire skin off. If I ever re-paint the wings, I'll paint all access panels separately and use stainless steel screws. After a couple annuals, the pain is going to come off the screws anyway.&lt;/p&gt;&#xA;" OwnerUserId="7007" LastActivityDate="2015-01-27T21:58:01.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12074" PostTypeId="2" ParentId="9676" CreationDate="2015-01-27T21:58:57.167" Score="1" Body="&lt;p&gt;There are two kinds of GPUs:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The ones that are fixed and supply power to the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The ones which are mobile, which are tugged to the stationary aircraft&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The cables are connected by &lt;a href=&quot;http://en.wikipedia.org/wiki/Groundcrew&quot; rel=&quot;nofollow&quot;&gt;groundcrew&lt;/a&gt; before the pilot shuts down all engines. It is different from pilot to pilot. The APU remains on while the aircraft is being serviced.&lt;/p&gt;&#xA;" OwnerUserId="7005" LastEditorUserId="1696" LastEditDate="2015-01-28T16:32:54.340" LastActivityDate="2015-01-28T16:32:54.340" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12076" PostTypeId="1" AcceptedAnswerId="12077" CreationDate="2015-01-27T22:20:48.823" Score="4" ViewCount="7622" Body="&lt;p&gt;Boeing 747 is commonly called &lt;strong&gt;Jumbo Jet&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How did it get this nickname and why other airplanes do not have nicknames?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Please note that I am not talking about official names, e.g, &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;Boeing 787 Dreamliner&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="1696" LastEditDate="2015-02-17T17:21:12.857" LastActivityDate="2015-08-04T20:00:06.257" Title="Why does the Boeing 747 have a nickname but other aircraft do not?" Tags="&lt;airliner&gt;&lt;aviation-history&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12077" PostTypeId="2" ParentId="12076" CreationDate="2015-01-27T22:20:48.823" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How Boeing 747 is called Jumbo Jet?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;noreferrer&quot;&gt;Boeing 747&lt;/a&gt; is the world's first wide-body aircraft. For a long time, it was the world's largest passenger aircraft&lt;sup&gt;1&lt;/sup&gt;. When Boeing was designing the 747 in mid-1960s, it expected that in the near future &lt;a href=&quot;https://en.wikipedia.org/wiki/Supersonic_transport&quot; rel=&quot;noreferrer&quot;&gt;supersonic travel&lt;/a&gt; would become the norm. Hence, there would not be a need for the passenger version of 747. Because of this, 747s were designed in a way that they can be easily converted into freighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pan_American_World_Airways&quot; rel=&quot;noreferrer&quot;&gt;Pan Am&lt;/a&gt;, being one of the first customers of 747, wanted to fit two rows of cargo containers&lt;sup&gt;2&lt;/sup&gt;, instead of one. This meant that the fuselage had to be at least 16 feet wide, wider than any airliner at that time. This would have worked fine for cargo, but it would make loading and unloading passengers very time-consuming. To accommodate this, Boeing engineers designed two aisles, which ran parallel through the length of the aircraft, hence the term &lt;a href=&quot;https://en.wikipedia.org/wiki/Wide-body_aircraft&quot; rel=&quot;noreferrer&quot;&gt;wide-body&lt;/a&gt; was coined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the press noticed the huge size, they described it with the catchy term &lt;em&gt;Jumbo Jet&lt;/em&gt;. It is also known as &lt;em&gt;Queen of the Skies&lt;/em&gt; but that is not common.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do other airplanes have nicknames?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airbus A380 dubbed as superjumbo by media. The only A380 sold as a business jet is called &lt;a href=&quot;http://www.ausbt.com.au/photos-inside-the-private-airbus-a380-flying-palace&quot; rel=&quot;noreferrer&quot;&gt;Flying Palace&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although there aren't &lt;em&gt;official&lt;/em&gt; nicknames of airplanes, almost all airplanes earned &lt;a href=&quot;http://www.b737.org.uk/aircraftnicknames.htm&quot; rel=&quot;noreferrer&quot;&gt;some nick names&lt;/a&gt;. &lt;a href=&quot;http://web.mit.edu/btyung/www/nickname.html&quot; rel=&quot;noreferrer&quot;&gt;This list&lt;/a&gt; contains nicknames for mostly military aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;a href=&quot;http://news.bbc.co.uk/2/hi/business/7061164.stm&quot; rel=&quot;noreferrer&quot;&gt;Airbus 380 took over&lt;/a&gt; as world's largest passenger airplane in 2007.&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt; At that time, cargo containers were cubes that measured 8 feet (2.44 m) per side.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="938" LastEditDate="2015-05-24T18:16:05.090" LastActivityDate="2015-05-24T18:16:05.090" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12078" PostTypeId="5" CreationDate="2015-01-27T22:30:46.030" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:30:46.030" LastActivityDate="2015-01-27T22:30:46.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12079" PostTypeId="4" CreationDate="2015-01-27T22:30:46.030" Score="0" Body="Companies or organizations that transport passengers and/or cargo by air." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:30:46.030" LastActivityDate="2015-01-27T22:30:46.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12080" PostTypeId="5" CreationDate="2015-01-27T22:31:43.643" Score="0" Body="&lt;p&gt;&lt;em&gt;Flaps&lt;/em&gt; are a type of &lt;a href=&quot;/questions/tagged/high-lift-device&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;high-lift-device&amp;#39;&quot; rel=&quot;tag&quot;&gt;high-lift-device&lt;/a&gt; generally mounted on a wing's trailing (rear) edge.  Most types of flap increase lift by increasing the wing's camber (the curvature of its upper surface), its area, or both.  A flap can also be combined with an aircraft's &lt;a href=&quot;/questions/tagged/ailerons&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ailerons&amp;#39;&quot; rel=&quot;tag&quot;&gt;ailerons&lt;/a&gt; to form a &lt;a href=&quot;/questions/tagged/flaperon&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flaperon&amp;#39;&quot; rel=&quot;tag&quot;&gt;flaperon&lt;/a&gt;, which decreases weight compared to having separate flaps and ailerons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The types of flap include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Plain flaps&lt;/em&gt;, which are simply a hinged section of the trailing edge that swivels downwards to increase the wing's camber.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Split flaps&lt;/em&gt;, in which the lower surface of the trailing edge swivels downwards, while the upper surface stays put.  This deflects air downwards and increases lift, but also considerably increases drag, acting as &lt;a href=&quot;/questions/tagged/airbrakes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbrakes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbrakes&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Fowler flaps&lt;/em&gt;, which slide backwards from the wing's trailing edge and then swivel downwards, increasing both the wing's area and its camber.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Slotted flaps&lt;/em&gt;, a modification of a plain or Fowler flap where one or more slots open up in the wing when the flaps extend, improving the flap's resistance to flow separation at a high &lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Blown flaps&lt;/em&gt;, where compressed air or engine exhaust is blown over the surface of the flap (and sometimes also the wing itself), dramatically increasing lift, but also dramatically increasing complexity, slightly decreasing maximum engine thrust, and aggravating the consequences of an &lt;a href=&quot;/questions/tagged/engine-failure&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine-failure&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine-failure&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Gouge flaps&lt;/em&gt;, which are like Fowler flaps, but swivel down at the same time as they move backwards, instead of after.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Junkers flaps&lt;/em&gt;, which are like plain flaps, but are mounted below the wing's trailing edge rather than attached to it.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Zap flaps&lt;/em&gt;, which behave like Gouge flaps, but where the flap moves only partway backwards as it swivels down.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Gurney flaps&lt;/em&gt;, small perpendicular tabs mounted on the underside of the trailing edge, which cause high-pressure air to pile up underneath the wing, greatly improving said wing's lift.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Krueger flaps&lt;/em&gt;, which, despite their name, are actually a type of &lt;a href=&quot;/questions/tagged/high-lift-device&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;high-lift-device&amp;#39;&quot; rel=&quot;tag&quot;&gt;high-lift-device&lt;/a&gt; mounted on the wing's &lt;em&gt;leading&lt;/em&gt; edge, more akin to &lt;a href=&quot;/questions/tagged/slats&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;slats&amp;#39;&quot; rel=&quot;tag&quot;&gt;slats&lt;/a&gt; or droops.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information, see &lt;a href=&quot;https://en.wikipedia.org/wiki/Flap_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Wikipedia page on flaps&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-10-19T08:58:27.727" LastActivityDate="2019-10-19T08:58:27.727" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12081" PostTypeId="4" CreationDate="2015-01-27T22:31:43.643" Score="0" Body="Surfaces that extend from the wings to increase lift, allowing flight at slower speeds (such as for takeoff and landing)." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2018-12-28T17:52:29.193" LastActivityDate="2018-12-28T17:52:29.193" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12082" PostTypeId="5" CreationDate="2015-01-27T22:32:47.440" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:32:47.440" LastActivityDate="2015-01-27T22:32:47.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12083" PostTypeId="4" CreationDate="2015-01-27T22:32:47.440" Score="0" Body="Procedures for navigating based on cockpit instruments rather than visual references outside the cockpit." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:32:47.440" LastActivityDate="2015-01-27T22:32:47.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12084" PostTypeId="5" CreationDate="2015-01-27T22:34:26.257" Score="0" Body="&lt;p&gt;A &lt;strong&gt;thrust reverser&lt;/strong&gt; (often shortened to simply &lt;strong&gt;reverser&lt;/strong&gt;) is a device or mechanism that allows the thrust from an aircraft’s &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt; (s) to be redirected forwards so it slows the aircraft down rather than speeding it up. &#xA; Thrust reversers are mostly used during &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt;, but are even more useful in the rare event of a &lt;a href=&quot;/questions/tagged/rejected-takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rejected-takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;rejected-takeoff&lt;/a&gt;; in both cases, there benefits are most pronounced when there is considerable &lt;a href=&quot;/questions/tagged/runway-contamination&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;runway-contamination&amp;#39;&quot; rel=&quot;tag&quot;&gt;runway-contamination&lt;/a&gt;, where stopping an aircraft without the use of thrust reversers can take as much as three times as much distance as stopping it &lt;em&gt;with&lt;/em&gt; reversers does.  Thrust reversers are one of three main ways of slowing an aircraft down; the others are wheel &lt;a href=&quot;/questions/tagged/braking&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;braking&amp;#39;&quot; rel=&quot;tag&quot;&gt;braking&lt;/a&gt;, on the one hand, and drag-producing devices (&lt;a href=&quot;/questions/tagged/spoilers&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;spoilers&amp;#39;&quot; rel=&quot;tag&quot;&gt;spoilers&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/airbrakes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbrakes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbrakes&lt;/a&gt;), on the other hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both &lt;a href=&quot;/questions/tagged/propeller&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;propeller&amp;#39;&quot; rel=&quot;tag&quot;&gt;propeller&lt;/a&gt; aircraft and &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;-powered aircraft can use thrust reversal, although they do this in very different ways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft equipped with &lt;a href=&quot;/questions/tagged/variable-pitch&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;variable-pitch&amp;#39;&quot; rel=&quot;tag&quot;&gt;variable-pitch&lt;/a&gt; propellers can, with most types of variable-pitch propeller, move their propeller blades to a negative pitch angle, so that, when the propeller spins, it pushes air forwards, rather than backwards, and, thereby, slows the aircraft down rather than speeding it up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pZSWp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pZSWp.png&quot; alt=&quot;Propeller reversal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines, in contrast, are not generally equipped with variable-pitch fan or compressor blades; as a result, thrust reversers for jets have to redirect the engine’s exhaust forwards after the rest of the engine has already accelerated it backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are four main ways to do this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Target-type reversers&lt;/em&gt; are what most everyone probably thinks of when they hear the phrase “thrust reverser”; they have a pair of large, moveable doors mounted just behind the engine, which, when reverse thrust is commanded, swing backwards to form a “bucket” behind the engine which catches its exhaust and redirects it forwards.  This type of reverser is typically found on &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt; and low-bypass &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt; engines, as using target-type reversers on a turbofan with a high &lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt; (and, thus, a large diameter) would require impractically-large bucket doors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HkVZK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HkVZK.png&quot; alt=&quot;Target reversal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Clamshell-type reversers&lt;/em&gt;, instead of using external bucket doors that swing shut behind the engine, use swivelling doors &lt;em&gt;inside&lt;/em&gt; the engine, which pivot to block off the air’s path out the tailpipe and open paths for it to exit the engine in the forward direction through openings in the engine cowling.  There are two distinct variants of clamshell-type reversers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One variant, used mainly on low-bypass turbofans (although it was also used on a few early high-bypass turbofans), has clamshell doors that redirect the engine’s entire output - both the hot core air and the (relatively) cold bypass air.  This variant produces more deceleration, for a given engine and power output, than the other variant (see below), but also has a shorter lifetime and higher maintenance costs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7gPEE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7gPEE.png&quot; alt=&quot;Hot clamshell reversal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The other variant, used on high-bypass turbofans, redirects only the engine’s bypass air - the core air passes straight through, unaffected.  This works because the vast majority of a high-bypass turbofan’s thrust is generated by the bypass air, with the engine core directly contributing only a small amount of thrust; therefore, redirecting a high-bypass turbofan’s bypass air, but not its core air, will still generate net reverse thrust.  As the engine’s core airflow continues to produce forward thrust even with the reverser deployed, this type of reverser (all else being equal) produces less deceleration than one that also redirects the core airflow; however, as the clamshell doors are not exposed to the hot, corrosive combustion gasses and particulates in the core exhaust, they last much longer, are more reliable, and have lower maintenance costs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vBVvw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vBVvw.png&quot; alt=&quot;Cold clamshell reversal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final type of reverser is the &lt;em&gt;cascade-type reverser&lt;/em&gt;, used on high-bypass turbofans - especially on the &lt;em&gt;very large&lt;/em&gt; high-bypass turbofans powering newer widebody airliners, although it also sees use on some smaller high-bypass turbofans as well.  Cascade reversers redirect only the engine’s bypass air (as a result, they are also sometimes known as &lt;em&gt;cold-stream reversers&lt;/em&gt;, although, as noted above, many clamshell-type reversers &lt;em&gt;also&lt;/em&gt; redirect only bypass air); they do this by sliding the entire rear portion of the engine cowling backwards, which opens up a gap for air to blow forwards through and operates a mechanism that blocks off the rear portion of the bypass duct so that the air can’t continue to go backwards.  As the redirected air can exit throughout the entire circumference of the engine rather than just through discrete doorways, cascade-type reversers work better than clamshell-type reversers for redirecting the huge amounts of bypass air from the largest turbofans; they also, unlike target-type or clamshell-type reversers, do not protrude sideways when deployed, which makes them very useful on engines with low ground clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3MRz9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3MRz9.png&quot; alt=&quot;Cascade reversal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, here’s a diagram explaining the differences between the different types of jet-engine thrust reversers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vJ6T1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vJ6T1.png&quot; alt=&quot;Jet reverser types&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information regarding thrust reversers, see the Wikipedia articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_reversal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reversers in general&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Target-type_thrust_reversal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Target-type reversers, specifically&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-03-15T03:25:35.407" LastActivityDate="2019-03-15T03:25:35.407" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12085" PostTypeId="4" CreationDate="2015-01-27T22:34:26.257" Score="0" Body="A system that redirects the air exiting a jet engine forwards or outwards, helping to slow the plane down (usually during landing)." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-01-14T15:46:34.797" LastActivityDate="2019-01-14T15:46:34.797" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12086" PostTypeId="5" CreationDate="2015-01-27T22:35:27.793" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:35:27.793" LastActivityDate="2015-01-27T22:35:27.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12087" PostTypeId="4" CreationDate="2015-01-27T22:35:27.793" Score="0" Body="The process of performing flights for the purpose of testing an aircraft and related systems." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:35:27.793" LastActivityDate="2015-01-27T22:35:27.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12089" PostTypeId="5" CreationDate="2015-01-27T22:40:38.580" Score="0" Body="&lt;p&gt;Questions may involved cost or other requirements for aircraft ownership.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-10-07T15:00:27.557" LastActivityDate="2015-10-07T15:00:27.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12090" PostTypeId="4" CreationDate="2015-01-27T22:40:38.580" Score="0" Body="Questions about the aspects involved with owning an aircraft." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-10-07T15:00:27.557" LastActivityDate="2015-10-07T15:00:27.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12091" PostTypeId="5" CreationDate="2015-01-27T22:49:04.927" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:49:04.927" LastActivityDate="2015-01-27T22:49:04.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12092" PostTypeId="4" CreationDate="2015-01-27T22:49:04.927" Score="0" Body="Advanced Aviation Training Devices, such as simulators that are used for training pilots in more advanced topics." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-27T22:49:04.927" LastActivityDate="2015-01-27T22:49:04.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12093" PostTypeId="2" ParentId="8726" CreationDate="2015-01-28T00:03:47.037" Score="4" Body="&lt;p&gt;In modern military and commercial aviation, aircraft power is 3-phase 115V at 400Hz (AC), and 28V DC.  This is standard just about everywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AC power is 3-phase 115V AC at 400Hz (alternating current).  When the engines are spinning, this power is produced by onboard generators (alternators) feeding redundant power buses.  On the ground, this is typically sourced from a ground power unit (GPU).  During emergencies, AC power may be produced by an auxiliary power unit (APU).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DC power is provided by converting a portion of the 115V AC power to 28 volts DC for powering many of the avionics systems and charging the aircraft battery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT: My apologies, contrary to my original answer (I was thinking powering the cockpit displays/indicators mostly), a lot of navigation and pitch/attitude sensors take 26vac/400Hz input power.  Rate gyros, compass, flux valve, etc.  See, e.g. &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=CESSNA_Citation_Bravo-Electrical.pdf&quot; rel=&quot;nofollow&quot;&gt;this section&lt;/a&gt; from a Cessna Citation.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-01-28T23:28:38.743" LastActivityDate="2015-01-28T23:28:38.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12094" PostTypeId="1" AcceptedAnswerId="12095" CreationDate="2015-01-28T00:40:24.130" Score="9" ViewCount="1401" Body="&lt;p&gt;Saw the &lt;a href=&quot;https://www.youtube.com/watch?v=VAdpKpppZiA&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; of the helicopter chopping off its own refueling probe. That made me wonder what the stall speed of the tanker is, and how difficult it is to fly slow enough for the helis to keep up.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2019-03-08T18:10:47.233" LastActivityDate="2019-03-08T18:10:47.233" Title="What is the stall speed of the KC130?" Tags="&lt;military&gt;&lt;stall&gt;&lt;refueling&gt;&lt;c-130&gt;&lt;tanker&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12095" PostTypeId="2" ParentId="12094" CreationDate="2015-01-28T00:50:47.597" Score="11" Body="&lt;p&gt;The stall speed is around 95-100 knots for the older F variant, and something like 90-95 knots for the newer J variants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A KC-130 can refuel between around 100 and 270 knots. The lower end of this is well within the maximum speed of many military helicopters, eg the Pave Hawk, Black Hawk, Chinoook or Sea Stallion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That leaves an &quot;overlap&quot; of around 20-40 knots, without having to approach too close to either the stall speed of the KC-130 (around 90-95 knots) or the VNE of the helicopter (usually between 140 and 170 knots for a military helicopter). This is enough for aerial refuelling, which usually states a fairly tight bracket for the refuelling speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned &lt;a href=&quot;http://www.fas.org/man/dod-101/sys/ac/c-130.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The United States Marine Corps has chosen the KC-130J tanker to replace its aging KC-130F tanker fleet. The new KC-130J offers increased utility and much needed improvement in mission performance. As a force multiplier, the J tanker is capable of refueling both fixed wing and rotary wing aircraft as well as conducting rapid ground refueling. The refueling speed envelope has been widened from 100 to 270 knots indicated airspeed, offering more capability and flexibility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="65" LastEditDate="2015-01-28T22:34:15.723" LastActivityDate="2015-01-28T22:34:15.723" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12096" PostTypeId="1" AcceptedAnswerId="12105" CreationDate="2015-01-28T03:06:14.267" Score="7" ViewCount="2392" Body="&lt;p&gt;We were having a discussion in our ground school that power will make the plane ascend or descend and that you use the stick for speed, forward for higher speed and back for slower speed. So does that mean as you fly higher, that means you increase power and ascend, and then fly from point A to point B, you will burn more fuel compared to if you went from point A to point B at reduced power, hence lower altitude? &lt;/p&gt;&#xA;" OwnerUserId="173" LastEditorUserId="5517" LastEditDate="2015-02-19T19:34:15.327" LastActivityDate="2015-02-19T19:34:15.327" Title="What is the relationship between power and fuel efficiency?" Tags="&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12098" PostTypeId="1" AcceptedAnswerId="12106" CreationDate="2015-01-28T04:08:26.857" Score="5" ViewCount="867" Body="&lt;p&gt;There is often tremendous confusion between bearing, track and similar terms.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/w/index.php?title=Bearing_%28navigation%29&amp;amp;oldid=644504841&quot; rel=&quot;nofollow noreferrer&quot;&gt;On Wikipedia, I saw the following sentence&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;h1&gt;NOTE CAREFULLY, THE FOLLOWING SENTENCE IS &lt;em&gt;WRONG&lt;/em&gt;...&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In aerial navigation, bearing refers to the actual compass direction&#xA;of the forward course of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h1&gt;...NOTE CAREFULLY, THAT SENTENCE IS &lt;em&gt;WRONG&lt;/em&gt;.&lt;/h1&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;PLEASE NOTE I believe that quote is totally incorrect, do not quote this page!&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;I refer to the &amp;quot;where the aircraft is going/pointing&amp;quot; as either &lt;strong&gt;&amp;quot;track&amp;quot;&lt;/strong&gt; (the vector of motion over the ground) or &lt;strong&gt;&amp;quot;heading&amp;quot;&lt;/strong&gt; (where the nose is pointing). Whereas, &amp;quot;bearing&amp;quot; means bearing &lt;em&gt;regarding some distant object&lt;/em&gt;, (that could be either relative or absolute), and does not relate in any way to &amp;quot;where the aircraft is going/pointing&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;{Indeed, you could just be standing somewhere - not moving and not in a vehicle - and very much talk about &amp;quot;bearings&amp;quot; to various landmarks.}&lt;/p&gt;&#xA;&lt;p&gt;In other words, I have always thought &lt;a href=&quot;https://aviation.stackexchange.com/a/8947/3288&quot;&gt;this diagram&lt;/a&gt; is correct, and the only usage.&lt;/p&gt;&#xA;&lt;p&gt;My question for actual pilots, controllers, etc, is this! ...&lt;/p&gt;&#xA;&lt;p&gt;In fact, &lt;strong&gt;am I correct&lt;/strong&gt; that the quoted sentence above is totally wrong?&lt;/p&gt;&#xA;&lt;p&gt;Further: am I being &amp;quot;too dogmatic&amp;quot;? Hence specifically: is it the case that, in aviation, perhaps you &lt;strong&gt;sometimes do&lt;/strong&gt; use &amp;quot;bearing&amp;quot; loosely to mean track or heading?&lt;/p&gt;&#xA;&lt;p&gt;Let me repeat myself: I'm pretty sure I understand what bearing means and what track means.  But the wiki quote in question, says the opposite: in fact, is it just plain utterly 100% incorrect, a typo? &lt;strong&gt;Or, am I naive...&lt;/strong&gt; ie, you dudes sometimes do use &amp;quot;bearing&amp;quot; to mean what I call track?&lt;/p&gt;&#xA;&lt;p&gt;{Just TBTC ... for me &amp;quot;bearing&amp;quot; cannot be used about &amp;quot;us&amp;quot;. The sentence &amp;quot;our bearing..&amp;quot; is meaningless.  You use bearing about another object. &amp;quot;What's the bearing to blah...&amp;quot; [Of course, that could be implicit, ie, &amp;quot;is our bearing still 123?&amp;quot; meaning, I'm still talking about bearing to Sydney as in the previous sentence...].}&lt;/p&gt;&#xA;&lt;p&gt;As a curiosity: physics programmers (for games, whatever) constantly use these terms, and of course, we have to use them really precisely like any programming. You can imagine a character or whatever (perhaps a car in GTA!) has all these qualities, they are discussed constantly in relation to physics of the virtual objects in all senses, AI paths of tanks, etc etc.  Next time I scream at someone &amp;quot;that's not bearing you idiot, that's track&amp;quot; I want to be on a sound footing!&lt;/p&gt;&#xA;" OwnerUserId="3288" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-06-08T20:04:09.663" Title="Is this &quot;bearing&quot; sentence utterly incorrect?" Tags="&lt;navigation&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12099" PostTypeId="1" AcceptedAnswerId="12101" CreationDate="2015-01-28T05:05:19.320" Score="15" ViewCount="11023" Body="&lt;p&gt;I have noticed and read in books that low wing aircraft have higher dihedral than high wing aircraft. Dihedral is design feature for lateral stability so should be needed for both designs. So why is it more pronounced in low wing designs?&lt;/p&gt;&#xA;" OwnerUserId="173" LastActivityDate="2019-12-12T20:41:07.797" Title="Why do low wing aircraft have higher dihedral than high wing aircraft?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12100" PostTypeId="2" ParentId="12099" CreationDate="2015-01-28T05:25:39.290" Score="3" Body="&lt;p&gt;High-wing aircraft already have better roll stability due to their vertical center of gravity located under the wing than low-wing aircraft (with vertical CG located above the wing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.mnbigbirds.com/images/PDF%20Files/Dihedral_Art.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;a source other than Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the center of gravity is below the wing, the weight tends to restore the upright position. This is known as pendulum stability or the keel effect. If the CG is&#xA;  above the wing, the weight is destabilizing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-01-28T11:53:29.890" LastActivityDate="2015-01-28T11:53:29.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12101" PostTypeId="2" ParentId="12099" CreationDate="2015-01-28T05:42:01.080" Score="19" Body="&lt;p&gt;There are several sources for a sideslip-induced rolling moment:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The dihedral angle $\nu$ of the wing, which will increase the local angle of attack $\alpha$ on the windward wing according to $\Delta\alpha = \beta\cdot sin\nu$; $\beta$ being the angle of sideslip,&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/an-225-wing-configuration&quot;&gt;sweep angle $\varphi$ of the wing&lt;/a&gt;, which in a sideslip causes a de-sweeping of the airflow over the windward wing (and an increased sweep effect on the leeward wing). The local change in angle of attack is $\Delta\alpha = (cos(\varphi±\beta)-cos\varphi)\cdot(\alpha-\alpha_0)$ and is proportional to the angle of attack,&lt;/li&gt;&#xA;&lt;li&gt;The crossflow around the fuselage (see sketch below for illustration, sorry, no simple formula here), and&lt;/li&gt;&#xA;&lt;li&gt;The location of the vertical tail, or more precisely, the side force created on it by a sideslip angle in relation to the location of the center of gravity. This effect dictated the anhedral of aircraft like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;noreferrer&quot;&gt;F-104 Starfighter&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/7980/in-a-slip-or-skid-how-does-one-wing-have-a-higher-angle-of-attack-and-more-lift/7983#7983&quot;&gt;this answer&lt;/a&gt; for a more complete explanation of effect 3. The sketch below is taken from the linked answer and shows a high and a low wing configuration in sideslip. The thin blue arrows indicate the sideways component of airflow $v_{\infty}\cdot sin\beta$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ogOgZ.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, some rolling due to sideslip is good, but too much must be avoided, and dihedral is used to complement the other effects such that the total is just right. A high wing already provides some positive rolling moment due to sideslip (negative $c_{l_{\beta}}$: When you deflect rudder to the left, the resulting sideslip should roll the aircraft to the left, too), so the wing doesn't need to contribute as much (by means of dihedral) as in low wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dihedral (or for that matter, even a low center of gravity) will not roll the aircraft level: There is no aerodynamic way to achieve that! Dihedral will only give you a rolling moment when the aircraft sideslips.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-01-30T07:12:01.737" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12102" PostTypeId="2" ParentId="12055" CreationDate="2015-01-28T06:00:13.560" Score="11" Body="&lt;h2&gt;Effect on Aerodynamic Coefficients&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is possible to locate a vertical fin, as well as a control surface, ahead of the center of gravity.  $c_{n_r}$ (yaw-induced yawing moment or yaw damping) will not likely change much, all other things being equal. $c_{n_\beta}$ (sideslip-induced yawing moment or directional stability), on the other hand, will be reduced, perhaps becoming negative. Any sideslip will therefore result in a yaw moment which increases the sideslip.  Expressed in linear control theory terms, this will be a pole in right hand plane when you plot the complex solution of the equations of motion. It is an unstable configuration.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Active Control&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As Peter mentioned, it is possible to remain in control in this configuration by means of active control.  Active control tends to be somewhat tiring for a human operator if it is possible at all.  Incidentally, this kind of instability existed in the lateral axis of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8077/why-did-moving-the-cg-aft-on-the-wright-brothers-plane-improve-handling&quot;&gt;1903 Wright Flyer&lt;/a&gt;, which was configured with a canard of considerable proportion. It was reportedly quite tiring to keep stable.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;CP ahead of CG&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are advantages to having a center of pressure ahead of the center of gravity, the chief being agility.  Back in control terms, the farther you move poles to the right, toward instability, the faster or &quot;twitchy-er&quot; the response.  The &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt; is configured this way and has been the standard of maneuverability for quite some time, requiring computers and fly-by wire for stability augmentation.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Control surfaces ahead of CG&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is also advantageous for maneuverability to have control surfaces ahead of the CG.  In this case it is for avoiding a feature of control termed &quot;non-minimum phase&quot; response.  For a conventional, tail-configured aircraft, when a climb is commanded, the tail is forced down, leading to a net reduction in lift until an increase of angle of attack is developed.  This is non-minimum phase response.  It was necessary to initially go the opposite direction from that which was desired.  In canard configurations, this is not the case, first the nose climbs, then everything climbs.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Put them together...&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Forward control surfaces, forward center of pressure and a stability augmentation system with adequate dynamic pressure make for one heck of a maneuverable package.  This is a common recipie for tactical missiles.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-01-28T07:31:10.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12103" PostTypeId="2" ParentId="12055" CreationDate="2015-01-28T07:20:06.683" Score="8" Body="&lt;p&gt;&lt;strong&gt;Well, it is. It has been done &lt;a href=&quot;http://en.wikipedia.org/wiki/Pterodactyloidea&quot; rel=&quot;nofollow noreferrer&quot;&gt;since maybe 160 Million years&lt;/a&gt;.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Pterodactyloidea branch of flying saurians had long beaks, in most cases balanced by a large bony structure at the back of their heads, which provided lateral control. This is their only body part with noticeable side area, so no other part of their bodies could serve a similar purpose. Controlling direction like this helps to immediately change course to whatever the animal looks at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C1jhe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C1jhe.jpg&quot; alt=&quot;Aerodactylus scolopaciceps&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Pterodactylus antiquus (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/b/b3/Aerodactylus_scolopaciceps.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the head was ahead of their center of gravity, the configuration is statically unstable and needs continuous control corrections. On the other hand, it provides very quick responses. This works and has been proven several times by &lt;a href=&quot;http://www.pterosaur.org.uk/PDB2012/T/Flying/Flying01.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;pterosaur-shaped flying models&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another branch, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rhamphorhynchoidea&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rhamphorhynchoidea&lt;/a&gt;, had a tail which provided additional lateral and longitudinal control. Palaeobiologists are still arguing, however, whether the tip of the tail was oriented horizontally or vertically in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern times weight and drag savings were the motivation for placing the fin at the tip of an airplane. The &lt;a href=&quot;http://en.wikipedia.org/wiki/HOTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;British space plane proposal HOTOL&lt;/a&gt; had such an actively controlled fin just on top of the fuselage nose. Also, many air-to-air missiles have their moveable control surfaces close to the tip, and those are balanced by bigger fins at the back. Both together make them canards in lateral and longitudinal control.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-05-25T22:34:22.893" LastActivityDate="2018-05-25T22:34:22.893" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="12104" PostTypeId="2" ParentId="12009" CreationDate="2015-01-28T07:40:06.393" Score="5" Body="&lt;p&gt;Answer based on information found on-line. Related documentation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;USAF &lt;a href=&quot;http://www.bits.de/NRANEU/others/END-Archive/AFI11-2C-130V3%2812%29.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-130 Operations Procedures&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;C-130T &lt;a href=&quot;https://info.publicintelligence.net/USNavy-C130T.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Manual&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Lockheed &lt;a href=&quot;http://www.c-130hercules.net/LSN/No4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;News Service, 1957&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;KC-130 &lt;a href=&quot;http://www.fas.org/man/dod-101/sys/ac/kc-130.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Specifications&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;KC-130J &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/kc-130-specs.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Specifications&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;C-130 &lt;a href=&quot;http://www.wingsoverkansas.com/alford/a1069/&quot; rel=&quot;nofollow noreferrer&quot;&gt;HALO Practices&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IABjq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;C-130J Hercules&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://www.flightglobal.com/airspace/media/militaryaviation1946-2006cutaways/lockheed-c-130j-hercules-cutaway-11676.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Global&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The KC-130 Hercules is the tanker variant of the C-130 Hercules. The cargo opening consists of a door, and a ramp which can be operated separately. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The door is opened by rotating up and inwards the top panel.&lt;/li&gt;&#xA;&lt;li&gt;The ramp is opened by rotating down and outwards the lower panel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/A1eoW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/A1eoW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://cqplanespotting.blogspot.fr/2017/08/royal-australian-air-force-raaf.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;CQ Planes Spotting&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;KC-130 / C-130 have a &lt;a href=&quot;http://www.aircraftsandplanes.com/lockheed-c-130-hercules.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;good maneuverability&lt;/a&gt; at low speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the the C-130 flight manual:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Door and loading ramp are operated at a &lt;strong&gt;speed of 150 KIAS&lt;/strong&gt;, with &lt;strong&gt;flaps down at 50%&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Same conditions for flying with door and/or loading ramp open.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Low speed adjustments:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reducing speed from 300 kt to 150 kt requires &lt;strong&gt;nose up trimming&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The center of gravity may be adjusted by &lt;strong&gt;ballasting fuel&lt;/strong&gt; in the tanks (refueling tank and aircraft tanks).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Opening the ramp will change the aerodynamic shape of the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The ramp will not be moved past the horizontal position (only need for full down position is to load cargo on the ground).&lt;/li&gt;&#xA;&lt;li&gt;Moves the &lt;strong&gt;nose down&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Balanced by some &lt;strong&gt;trim accordingly&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If loads are dropped (pallets, paratroopers) or fuel is delivered, the center of gravity will roll back, with a significant nose-down tendency, and trimming will be required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Opening the door will be less of an issue as seen on the image below:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft is near level.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1iJmY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sup&gt;Above: KC-130J Hercules (source: &lt;a href=&quot;http://www.military.com/equipment/kc-130j-hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Military.com&lt;/a&gt;).&lt;/sup&gt;&lt;br&gt;&#xA;Note that the attitude is not so far from level, in spite the door is open.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-12-11T17:41:38.343" LastActivityDate="2017-12-11T17:41:38.343" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12105" PostTypeId="2" ParentId="12096" CreationDate="2015-01-28T07:55:25.450" Score="13" Body="&lt;p&gt;It's not this does that and nothing else. It is always a combination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In climb you need to provide more energy to the aircraft because you are increasing it's potential energy. This can be taken from the energy which would have been spent to overcome drag in horizontal flight by flying slower. Less energy is needed to sustain the now lower flight speed, so some is left for climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you pull on the stick, you trim the aircraft for a lower flight speed (at least if you fly a naturally stable configuration), so some of the excess energy needs to be spent in other ways. The aircraft climbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you advance the throttle, the trimmed speed will stay the same, but now more energy is available to be spent. It will be spent on climbing, because speed is already set by your elevator angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a non-supercharged (normally aspirated) piston engine, the decreasing air density with increasing altitude will provide less air with every filling of the pistons. You need to lean the engine to keep the fuel-to-air ratio constant, so the engine will consume less fuel at the same engine speed, but also provide less power and thrust. Since air is also thinner for all other parts of the airplane, your true air speed will increase, your drag will decrease at the same true air speed and you can fly faster. But since your normally aspirated engine will provide less power, you need to advance the throttle in order to keep your attitude, speed, and climb rate. At some point, you will reach maximum power, and as you climb further, climb speed will decline until you reach the maximum flight altitude your airplane is capable of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying higher will increase the efficiency of the engine due to lower air temperature, but this effect is small for piston-powered aircraft. Once you switch to supercharged aircraft, turboprops, and jets, however, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983#4983&quot;&gt;their much higher maximum flight altitude will make flying higher markedly more efficient&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight speed, however, does make a substantial difference, especially for piston-powered aircraft. Their &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;optimum cruise lift coefficient&lt;/a&gt; is $c_L = \sqrt{c_{D0}\cdot\pi\cdot\Lambda}$ and is rather high. Flying low means that you will fly a lot faster than what this optimum demands, and the higher you fly, the closer you will be to this optimum, simply because your engine will not allow a higher speed. &lt;strong&gt;That&lt;/strong&gt; is why flying higher helps to fly more efficiently.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-01-28T13:50:36.787" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12106" PostTypeId="2" ParentId="12098" CreationDate="2015-01-28T08:12:02.433" Score="10" Body="&lt;h2&gt;Short answers&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Here's my answers to your questions, in order:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes, you are correct that the quote is wrong.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes, you are being too dogmatic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2(a). By the way, &lt;em&gt;you&lt;/em&gt; are also wrong.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The quote is incorrect.  Bearing is properly used the way you describe.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I misuse words all the time, but it's not common for me (or anyone I know) to swap bearing and track.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Longer explanation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The quote isn't correct because &lt;em&gt;magnetic track&lt;/em&gt; properly refers to the actual direction that the aircraft is moving, as read off the magnetic compass. However, you say that you refer to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the &quot;forward course of the aircraft&quot; as either track or heading. (Track, vector over ground, heading, z-axis of vehicle airframe.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Track and heading are &lt;em&gt;not&lt;/em&gt; the same thing, and neither one is necessarily the forward course of the aircraft.  &lt;em&gt;Track&lt;/em&gt; is the &lt;em&gt;actual&lt;/em&gt; vector over the ground.  &lt;em&gt;Heading&lt;/em&gt; is the direction in which the longitudinal axis of the aircraft is aligned.  &lt;em&gt;Course&lt;/em&gt; is the correct word for the forward course of the aircraft; the &lt;em&gt;intended&lt;/em&gt; (not actual) vector over the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you've got the definition of bearing right, but you've got track, heading, and course all mixed together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been known to say &quot;bearing&quot; to mean &quot;track&quot;, but it's usually only just after I've said &quot;What be our&quot;, and just before I'm about to say &quot;ye scurvy dog?&quot;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2016-06-08T20:04:09.663" LastActivityDate="2016-06-08T20:04:09.663" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12107" PostTypeId="2" ParentId="12096" CreationDate="2015-01-28T08:59:21.100" Score="18" Body="&lt;p&gt;Unfortunately, the cause and effect in this question is &lt;em&gt;really&lt;/em&gt; muddled up. Peter Kampf's excellent answer should explain most of what you need, but it might be that you find his answer difficult to understand because you're still operating under the idea that the stick &lt;em&gt;only&lt;/em&gt; manages speed and the throttle &lt;em&gt;only&lt;/em&gt; manages altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this is the case, please consider this analogy: imagine that there are three buckets of energy available to any aircraft: chemical, potential, and kinetic.  (note for the pedantic: yes, chemical energy is potential energy.  Go away.)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Chemical energy is stored as fuel (dead dinosaurs).  It is released by the engine and can be converted into either altitude or airspeed or both.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Potential energy is altitude below you - the energy which is stored in the aircraft as altitude.  It can be converted into airspeed, but not back into dead dinosaurs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Kinetic energy is airspeed - the momentum of the aircraft.  It can be converted into altitude, but not back into dead dinosaurs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As long as the engines are operating, the chemical energy &quot;bucket&quot; is always pouring energy into the other two buckets.  The throttle determines &lt;em&gt;how much&lt;/em&gt; energy is poured out per second.  The yoke (stick) determines the &lt;em&gt;distribution&lt;/em&gt; of that energy - whether the kinetic bucket is pouring energy into the potential bucket, or vice versa, or neither.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means is that if you want to ascend, it's not enough to say that you simply have to pull back on the stick, or that you simply need to increase throttle.  Merely increasing throttle with the nose pointed at the ground does not help you ascend.  Merely pulling back on the stick with the airplane already at the critical angle of attack does not help you ascend.  To ascend, you need to &quot;fill the altitude bucket&quot;, which (as Peter says) is always a combination of pitch and power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to your actual question regarding fuel efficiency, since it's based on false assumptions I will only say that it depends on the circumstances of the flight, but it is certainly &lt;em&gt;not&lt;/em&gt; correct to say that increased fuel consumption is &lt;em&gt;always&lt;/em&gt; the result of the greater throttle setting necessary to achieve a higher altitude.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2015-01-29T02:36:43.610" LastActivityDate="2015-01-29T02:36:43.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12108" PostTypeId="1" AcceptedAnswerId="12124" CreationDate="2015-01-28T10:00:45.353" Score="2" ViewCount="3838" Body="&lt;p&gt;Recently someone talked to me about the possibility of induction ice on the engine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He told me that because of conditions around fan and compressor blades (mainly because of pressure and temperature) some ice may form, under certain exterior conditions, and destruct the engine by ingestion or by stall of boundary layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question: It is really possible? If yes, can someone explain to me how it works?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't find proper explanation on Google.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I raised this question after this hypothesis:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Icing inside jet engines can become a hazard at high altitude near large thunderstorms, when moisture turns into tiny ice crystals that can be sucked inside an engine. If the ice melts but then freezes again on metal surfaces, accumulating ice can either break into chunks that damage turbine blades, or melt and douse the ignition system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wsj.com/articles/airasia-flight-8501-crash-possibly-caused-by-icing-indonesian-report-says-1420298553&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="1696" LastEditDate="2015-02-05T16:45:45.237" LastActivityDate="2015-02-05T16:45:45.237" Title="How does induction ice form in and affect jet engines?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12109" PostTypeId="1" AcceptedAnswerId="12118" CreationDate="2015-01-28T10:15:58.103" Score="28" ViewCount="12528" Body="&lt;p&gt;This question focus on jet airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;noreferrer&quot;&gt;De Havilland Comet's&lt;/a&gt; engine were mounted inside the wing, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde's&lt;/a&gt; engines were mounted underwing (as many jet engines) but without pylon. It seems jet airliners' engines are now mounted on pylon. That assumption goes wherever the engine is mounted (&lt;a href=&quot;http://www.airliners.net/photo/Swiss-International-Air/Airbus-A330-343/1899910&quot; rel=&quot;noreferrer&quot;&gt;underwing&lt;/a&gt; or at the &lt;a href=&quot;http://3.bp.blogspot.com/_aLP-tJxG13U/TUoWPItOihI/AAAAAAAAACY/tg7FM7qgtSQ/s1600/MD90+Pylon+Flaps+1.jpg&quot; rel=&quot;noreferrer&quot;&gt;rear&lt;/a&gt; of the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages of doing so (aerodynamic, maintenance, safety,...)? Is there some drawback (must be minimal as this design is dominant)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I don't want discussion about &lt;a href=&quot;https://aviation.stackexchange.com/questions/9680/why-not-mount-airliner-jet-engines-above-the-wings&quot;&gt;where to mount engine&lt;/a&gt; (underwing as for the B747, overwing as for the VFW-Fokker 614, at the rear as for the MD-80, ...), I'm curious about why we use pylons for all this designs.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2017-05-18T15:56:19.257" LastActivityDate="2017-05-18T15:56:19.257" Title="Why do we use pylons to mount the engines on jetliners?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;jet-engine&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12111" PostTypeId="2" ParentId="11889" CreationDate="2015-01-28T12:13:05.457" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;LIMITATIONS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PAGE : 001 APR 11 EASA APPROVED&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Model : 212 A &#xA;  AFM 1  &lt;/p&gt;&#xA;  &#xA;  &lt;hr&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.01&lt;/strong&gt; | INTRODUCTION&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Observance of the limitations contained in this chapter is required by law. When&#xA;  operating in accordance with an approved appendix or supplement to&#xA;  this manual, the limitations of this basic Airplane Flight Manual&#xA;  section apply, except as altered by such an appendix or supplement.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.02&lt;/strong&gt; | KINDS OF OPERATION&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The airplane is certified in the&#xA;  Transport Category, JAR 25 and ICAO annex 16 for day and night&#xA;  operations, in the following conditions when the appropriate equipment&#xA;  and instruments required by the airworthiness and operating&#xA;  regulations are approved, installed and in an operable condition :&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;VFR and IFR&lt;/li&gt;&#xA;  &lt;li&gt;Flight in icing conditions.&lt;/li&gt;&#xA;  &lt;li&gt;Reverse thrust taxi (single or twin engine) &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.03&lt;/strong&gt; | MINIMUM FLIGHT CREW&lt;/em&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2 pilots&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.04&lt;/strong&gt; | PERFORMANCE CONFIGURATION&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Refer to 6.01.03 for airplane configuration associated with certified&#xA;  performances. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.05&lt;/strong&gt; | MAXIMUM OPERATING ALTITUDE&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;25000 ft&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.06&lt;/strong&gt; | MANEUVERING LIMIT LOAD FACTORS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Gear and flaps retracted : + 2.5 to -- 1 g &lt;/li&gt;&#xA;  &lt;li&gt;Gear and/or flaps extended : + 2 to 0 g&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.07&lt;/strong&gt; | CONFIGURATION DEVIATION LIST&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Refer to 7.01.02 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.08&lt;/strong&gt; | NOISE CHARACTERISTICS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The aircraft meets the requirements of ICAO annex 16,&#xA;  Chapter 4 with no weight restriction. Refer to noise characteristics&#xA;  in Appendix 7.01.01 of this manual for noise levels. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.01.09&lt;/strong&gt; | MAXIMUM NUMBER OF PASSENGER SEATS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;74 as limited by emergency exits&#xA;  configuration &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.02.01&lt;/strong&gt; | WEIGHTS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;STRUCTURAL LIMITATIONS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MAXIMUM WEIGHT KG LB&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;RAMP 22970 50640 &lt;/li&gt;&#xA;  &lt;li&gt;TAKE-OFF 22800 50265 &lt;/li&gt;&#xA;  &lt;li&gt;LANDING 22350 49273 &lt;/li&gt;&#xA;  &lt;li&gt;ZERO FUEL 20800 45856 &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;PERFORMANCE LIMITATIONS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Maximum take-off weight and maximum landing weight may be reduced by performance&#xA;  requirements related to the following (see chapter 6) :&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;climb performance (first and second segment, final take-off and en route, approach and landing climb)&lt;/li&gt;&#xA;  &lt;li&gt;available runway length (take-off and landing)&lt;/li&gt;&#xA;  &lt;li&gt;tyre limit speed&lt;/li&gt;&#xA;  &lt;li&gt;brake energy limit, observe BRK TEMP alert for take-off&lt;/li&gt;&#xA;  &lt;li&gt;obstacle clearance (take-off and en route)&lt;/li&gt;&#xA;  &lt;li&gt;en route and landing weight&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.03.01&lt;/strong&gt; | AIRSPEEDS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;MAXIMUM OPERATING SPEED VMO / MMO&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This limit must not be intentionally exceeded in any flight regime.&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;VMO = 250 kt CAS&lt;/li&gt;&#xA;  &lt;li&gt;MMO = 0.55&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;MAXIMUM DESIGN MANEUVERING SPEED VA&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Full application of roll and yaw controls, as well as maneuvers that involve angles of attack near the stall&#xA;  should be confined to speeds below VA. &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;VA = 175 kt CAS &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;CAUTION: Rapidly alternating large rudder applications in combination with&#xA;  large sideslip angles may result in structural failure at any speed.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;MAXIMUM FLAPS EXTENDED OR OPERATING SPEEDS VFE &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;FLAPS 15 185 kt CAS&lt;/li&gt;&#xA;  &lt;li&gt;FLAPS 30 150 kt CAS&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;MAXIMUM LANDING GEAR EXTENDED OR OPERATING SPEEDS&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;VLE = 185 kt CAS &lt;/li&gt;&#xA;  &lt;li&gt;VLO &lt;/li&gt;&#xA;  &lt;li&gt;lowering = 170 kt CAS &lt;/li&gt;&#xA;  &lt;li&gt;retracting = 160 kt CAS &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.03.02&lt;/strong&gt; | OPERATIONAL PARAMETERS ENVIRONMENTAL ENVELOPE&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note : Refer&#xA;  to 2.04.05 for fuel temperature limitation. TAKE–OFF AND LANDING –&#xA;  Tail wind limit : 15 kt – Maximum mean runway slope : ±2 % &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.04.01&lt;/strong&gt; | ENGINES&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PRATT&amp;amp;WHITNEY CANADA PW127F or PW127M or PW127N &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Operating limits with no unscheduled maintenance action required;&#xA;  Beyond these limits refer to maintenance manual.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;OPERATING CONDITION TIME LIMIT TQ&#xA;  (%) ITT ($^\circ$C) NH (%) NL (%) NP (%) OIL PRESS (PSI) OIL TEMP ($^\circ$C)&#xA;  (&lt;sup&gt;2&lt;/sup&gt;) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;RESERVE TAKE OFF 10 mn (&lt;sup&gt;6&lt;/sup&gt;) 100 (&lt;sup&gt;1&lt;/sup&gt;) 800 103.2 104.2 101 55 to 65 0 to 125 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NORMAL TAKE OFF 5 mn 90 (&lt;sup&gt;1&lt;/sup&gt;) (&lt;sup&gt;5&lt;/sup&gt;)&#xA;  101.9 101.4 101 55 to 65 0 to 125&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MAXIMUM CONTINUOUS none (&lt;sup&gt;7&lt;/sup&gt;)&#xA;  90.9 (&lt;sup&gt;1&lt;/sup&gt;) 800 103.2 104.2 101 55 to 65 0 to 125 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GROUND IDLE 66 mini 40 mini (&lt;sup&gt;4&lt;/sup&gt;)&#xA;  -- 40 to 125 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;HOTEL MODE 715 55 to 65 125 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;TRANSIENT 20 s 120 840 106.4 106.8 106 (&lt;sup&gt;3&lt;/sup&gt;) 40 to 100 5 s 120 20 mn 140 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;STARTING 5 s 950 --54 mini &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Value linked to 100 % NP. &lt;/li&gt;&#xA;  &lt;li&gt;Oil temperature must be maintained above 45$^\circ$C to ensure protection for &#xA;  the engine air inlet against ice accumulation.&lt;/li&gt;&#xA;  &lt;li&gt;Permissible for completion of flight provided TQ does not exceed 75.2 %&#xA;  during climb and 73.13 % during cruise. &lt;/li&gt;&#xA;  &lt;li&gt;Up to 75 % NH only. &lt;/li&gt;&#xA;  &lt;li&gt;ITT limits depend on outside air temperature. Refer to 2.04 page 2.&lt;/li&gt;&#xA;  &lt;li&gt;Single engine operation only, beyond 5 mn.&lt;/li&gt;&#xA;  &lt;li&gt;MCT rating is the max&#xA;  power certified for continuous use. In-flight emergencies are the&#xA;  only conditions for which MCT use is authorized. &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;NOTE : Flight with an&#xA;  engine running and the propeller feathered is not permitted &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.04.02&lt;/strong&gt; | PROPELLERS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;TWO HAMILTON STANDARD HS 568 F &#xA;   – 1 GROUND OPERATION &#xA;  Engine run up must be performed into the wind.  Avoid static operation&#xA;  between 41.6 % and 62.5 % NP.  Avoid operation in feather above 66.6 %&#xA;  TQ. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GROUND OR FLIGHT OPERATION  If a propeller is involved in an&#xA;  overspeed or in an engine overtorque refer to the propeller&#xA;  maintenance manual. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;FLIGHT OPERATION  ATR airplanes are protected&#xA;  against a positioning of power levers below the flight idle stop in&#xA;  flight by an IDLE GATE device.  It is reminded that any attempt to&#xA;  override this protection is prohibited. Such positioning may lead to&#xA;  loss of airplane control or may result in an engine overspeed&#xA;  condition and consequent loss of engine power. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;04 POWER PLANT 2&#xA;  LIMITATIONS PAGE : 001 DEC 96 EASA APPROVED&#xA;  --Model : 212 A AFM 4 AUG 07 FEB 05 R JUL 06 SEP 06 R R R &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.04.03&lt;/strong&gt; | OILSYSTEM SPECIFICATION Refer to specification PWA 521 type II.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.04.04&lt;/strong&gt; | STARTER&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;3 starts with a 1 minute 30 seconds maximum combined starter running time followed by 4 minutes OFF.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.04.05&lt;/strong&gt; | FUELSYSTEM&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Acceptable fuels : Jet A, Jet A1, JP5 and RT, TS1. Use of JP4 and Jet B is prohibited. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;TEMPERATURE &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;For flight&#xA;  preparation, a minimum fuel temperature must be taken into account to&#xA;  ensure adequate relight :&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;3 4 o C JET A, JET A1 and RT, TS1.&lt;/li&gt;&#xA;  &lt;li&gt;2 6 o C for fuel type JP5. •Maximum temperature : 57 o C for fuel types JET A, JET A1, JP 5 and RT, TS1. &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;REFUELING &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Maximum pressure 3.5&#xA;  bars (50 PSI) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;USABLE FUEL &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The total quantity of fuel usable in each&#xA;  tank is : 2500 kg (5510 lbs) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE :Fuel remaining in the tanks when&#xA;  quantity indicators show zero is not usable in flight. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;UNBALANCE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Maximum fuel unbalance : 730 kg (1609 lbs) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;FEEDING &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Each electrical pump is able to supply one engine in the whole flight envelope. &lt;/li&gt;&#xA;  &lt;li&gt;One electrical pump and associated jet pump are able to supply both&#xA;  engines in the whole flight envelope &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.01&lt;/strong&gt; | AIR PRESSURIZATION&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Maximum differential pressure: 6.35 PSI&lt;/li&gt;&#xA;  &lt;li&gt;Maximum negative differential pressure 0.5 PSI&lt;/li&gt;&#xA;  &lt;li&gt;Maximum differential pressure for landing 0.35 PSI&lt;/li&gt;&#xA;  &lt;li&gt;Maximum differential pressure for OVBD VALVE full open selection 1 PSI&lt;/li&gt;&#xA;  &lt;li&gt;Maximum altitude for one bleed off operation 20000 ft&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.02&lt;/strong&gt; | HYDRAULIC SYSTEM&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All hydraulic fluids compliant with technical&#xA;  specification : NSA 307110 Compliant fluids are listed in the AMM&#xA;  (Chapter20, 20-31-30) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.03&lt;/strong&gt; | LANDING GEAR&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Do not perform pivoting (sharp turns) upon a landing gear with fully braked wheels except in case of emergency.&lt;/li&gt;&#xA;  &lt;li&gt;In case of ground speed over 165 kt all tires to be replaced.&lt;/li&gt;&#xA;  &lt;li&gt;Towbarless Towing is prohibited, unless the towbarless towing operations are performed in compliance with the appropriate&#xA;  operational requirements (JAR--OPS--1 for Commercial Air&#xA;  Transportation) using towbarless towing vehicles that are designed and&#xA;  operated to preclude damage to the aeroplane nose wheel steering&#xA;  system or which provide a reliable and unmistakable warning when&#xA;  damage to the steering system may have occurred. Towbarless towing&#xA;  vehicles that are specifically accepted for ATR aircraft are listed in&#xA;  ATR Service Letter 72--09--6001. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.04&lt;/strong&gt; | FLAPS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Holding with any flaps extended is prohibited in icing conditions (except for single engine operations). &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.05&lt;/strong&gt; | AUTOMATIC FLIGHT CONTROL SYSTEM (AFCS)&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Minimum height for autopilot engagement on take off : 100 ft&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;NAV mode for VOR approach, using either autopilot or flight director is authorized only if :&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;a co--located DME is available, and&lt;/li&gt;&#xA;  &lt;li&gt;DME HOLD is not selected&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Minimum height for use of either autopilot or flight director :&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Except during take off or executing an approach : 1000 ft&lt;/li&gt;&#xA;  &lt;li&gt;VS or IAS mode during approach : 160 ft&lt;/li&gt;&#xA;  &lt;li&gt;CAT 1 APP mode : 160 ft Refer to 7.01.03 for CAT II operation &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.06&lt;/strong&gt; | INSTRUMENTS MARKING&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Red arc or radial line : minimum and maximum limits Yellow arc : caution area Green arc : normal area &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.07&lt;/strong&gt; | CARGO DOOR OPERATION&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Do not operate cargo door with a lateral wind component of more than 45 kt. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;.../... 05 SYSTEMS 2 LIMITATIONS PAGE : 001 AUG 14 EASA APPROVED&#xA;  --Model : 212 A AFM 2&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.08&lt;/strong&gt; | ELECTRICAL&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Single DC GEN operation : In flight, if OAT exceeds ISA + 25, flight level must be limited to FL200. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.09&lt;/strong&gt; | MFC&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Take off with two or more failed MFC modules is prohibited &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.10&lt;/strong&gt; | COMMUNICATIONS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Not applicable &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;2.05.11&lt;/strong&gt; | TCAS&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When installed, Refer to appendix 7.01.0&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7017" LastEditorUserId="65" LastEditDate="2015-01-28T17:34:06.773" LastActivityDate="2015-01-28T17:34:06.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12112" PostTypeId="2" ParentId="655" CreationDate="2015-01-28T12:24:05.063" Score="-2" Body="&lt;p&gt;CAP393 UK In paragraph (5) ‘day’ means the time from half an hour before sunrise until half&#xA;an hour after sunset (both times exclusive), sunset and sunrise being&#xA;determined at surface level.&lt;/p&gt;&#xA;" OwnerUserId="7018" LastActivityDate="2015-01-28T12:24:05.063" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12113" PostTypeId="2" ParentId="12109" CreationDate="2015-01-28T13:04:43.583" Score="19" Body="&lt;p&gt;Mounting the engine on a pylon rather than integral to the wing, allows the aircraft to accept different engine types (eg, Rolls Royce, P&amp;amp;W, or GE) or different sizes of engines. For example the 757 had &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_757#Design_effort&quot;&gt;three different engines&lt;/a&gt;, each made by a different manufacturer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Launch customers Eastern Air Lines and British Airways selected the&#xA;  RB211-535C turbofan built by Rolls-Royce, which was capable of 37,400&#xA;  pounds-force (166 kN) of thrust.[19] This marked the first time that a&#xA;  Boeing airliner was launched with engines produced outside the U.S.[8]&#xA;  Domestic manufacturer Pratt &amp;amp; Whitney subsequently offered the 38,200&#xA;  pounds-force (170 kN) thrust PW2037,[19] which Delta Air Lines&#xA;  launched with an order for 60 aircraft in November 1980.[8][20]&#xA;  General Electric also offered its CF6-32 engine early in the program,&#xA;  but eventually abandoned its involvement due to insufficient&#xA;  demand.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pylon not only mounts the engine, but allows the different engine designs to adapt to the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, by disassociating the airframe from the engine, &lt;a href=&quot;https://www.youtube.com/watch?v=aOmCTehtFpI&quot;&gt;the engine can be repaired and replaced without disassembling the wing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-28T13:04:43.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12114" PostTypeId="2" ParentId="12108" CreationDate="2015-01-28T13:09:35.543" Score="2" Body="&lt;p&gt;As per the &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac%2000-6a%20chap%2010-12.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA's AC 00-6A Chapter 10&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ... compressor in a&#xA;  jet engine forms a partial vacuum in the intake. Adiabatic expansion&#xA;  in the partial vacuum cools the air. Ice forms when the temperature&#xA;  drops below freezing and sufficient moisture is present for&#xA;  sublimation....Induction icing potential varies greatly among&#xA;  different aircraft and occurs under a wide range of meteorological&#xA;  conditions. It is primarily an engineering and operating problem&#xA;  rather than meteorological.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-28T13:09:35.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12115" PostTypeId="1" CreationDate="2015-01-28T13:15:41.120" Score="3" ViewCount="542" Body="&lt;h2&gt;Have there been any 'proper' field trials of Automated Air Traffic Control?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Specifically, something that has been tested on larger aircraft and has come beyond the drawing board. By automated I'm implying that all decisions on movements are made by computers and instructions would be for instance transmitted digitally to the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2017-10-16T22:35:44.887" Title="Have there been any 'proper' field trials of Automated Air Traffic Control?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12116" PostTypeId="2" ParentId="12115" CreationDate="2015-01-28T13:19:51.510" Score="3" Body="&lt;p&gt;No&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer, but there has never been anything resembling a &quot;proper&quot; trial. There have been a few small scale, limited and tightly controlled trials, but nothing over any significant time frame, involving a significant number of aircraft, or even involving aircraft in &quot;normal&quot; use.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-28T13:19:51.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12117" PostTypeId="1" AcceptedAnswerId="12122" CreationDate="2015-01-28T13:26:39.143" Score="22" ViewCount="6905" Body="&lt;p&gt;Do airplanes have any way to quantify the turbulence like if shakes are there or the some kind of air drift is happening every parameter of these have some units but do collectively there is any such unit which can quantify the turbulence?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="14" LastEditDate="2015-01-29T05:40:11.467" LastActivityDate="2017-02-08T11:04:47.170" Title="Do we have a unit to measure turbulence?" Tags="&lt;turbulence&gt;&lt;units&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12118" PostTypeId="2" ParentId="12109" CreationDate="2015-01-28T13:33:20.470" Score="32" Body="&lt;p&gt;Engine placement was a tricky question when jets were introduced, and much has been learned since then. The initial idea was to mount them inside the fuselage or wing root. When they grew too big, they were closely mounted to the wing (&quot;underslung&quot; position, like in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot;&gt;Me-262&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Ilyushin_Il-28&quot;&gt;Il-28&lt;/a&gt; or the early &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737#737_Original_series&quot;&gt;Boeing 737&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the underslung position has two disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;More of the leading and trailing edges is obstructed, blocking space that would otherwise be used for slats and flaps. Consequently, an underslung position reduces maximum lift.&lt;/li&gt;&#xA;&lt;li&gt;The center of gravity of the engine is too far back. Moving it more forward helps to place the center of gravity of the wing ahead of its elastic line. Bending will now create an opposing inertial moment, which is very helpful to dampen flutter.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Starting to move the engine downwards away from the wing initially increases drag, because now a narrow slot opens between both with a tendency to separated flow. Only when the engine is moved downwards enough, the drag of the wing-engine arrangement reaches its minimum. This placement was chosen in the next generation of jets like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot;&gt;B-52&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_707&quot;&gt;Boeing 707&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving it still further down makes the pylon longer and thus increases the total drag again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big diameters of modern high-bypass ratio engines make it impractical to move it down enough to reach the drag minimum, but by moving it forward, the engine can again be lifted up, so a shorter landing gear becomes possible. Vortex generators are added if that pesky separation between engine and nacelle cannot be avoided.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-01-28T13:33:20.470" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12119" PostTypeId="2" ParentId="12117" CreationDate="2015-01-28T13:33:51.717" Score="22" Body="&lt;p&gt;Turbulence is described using the following qualitative descriptions  [&lt;a href=&quot;http://maps.avnwx.com/help/turb_desc.html&quot;&gt;Source&lt;/a&gt;]:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/G3bCu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Informally, you can use a g-meter to quantify turbulence, at least in the up-down direction, but I don't know of any particular values that equate to various types of turbulence&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4QA5s.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-28T13:43:34.893" LastActivityDate="2015-01-28T13:43:34.893" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12120" PostTypeId="2" ParentId="12115" CreationDate="2015-01-28T13:38:21.667" Score="3" Body="&lt;p&gt;There have been many trials involving large aircraft and various levels of ATC automation. However these trials do never involve more than a handful of aircraft. And always with a human Air Traffic Controller tightly in the loop for safety reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And never were &lt;em&gt;all&lt;/em&gt; decisions made by the automation system. Progress comes in small steps. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-28T13:46:35.277" LastActivityDate="2015-01-28T13:46:35.277" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12121" PostTypeId="2" ParentId="12096" CreationDate="2015-01-28T13:42:25.983" Score="4" Body="&lt;p&gt;I'll add one thing about engine efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft engines are either more, or at least not less, efficient at &lt;em&gt;higher&lt;/em&gt; power setting.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;In spark-ignited (gasoline) engines the throttle adds resistance to the intake when closed, so they are most efficient with throttle fully open and slightly lean mixture so that all fuel is burnt. Modern directly-injected engines often support &quot;ultra lean burn&quot; when throttle is left open and power is regulated by injecting less fuel, i.e. very lean mixture, but most aircraft engines are older designs that don't work well with too lean mixture, so they are less efficient with less throttle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Turbine engines are also more efficient at higher power. I am not sure about the reason, but probably because the high-pressure stage takes relatively less energy for driving the compressor leaving more power for the low pressure stage driving the propeller (at idle the power to propeller is minimal, but the core still spins quite fast; often around 60% rpm compared to full power).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Only diesel engines where power is controlled by amount of injected fuel only (corresponds to mixture in spark-ignited engines) are not less efficient at lower power settings, but at the cruise power they will not be any less efficient either.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;And now combine with the fact, that your drag is about the same at the same indicated speed independent of altitude, but at higher altitude the same indicated speed corresponds to higher true (and therefore ground) speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-28T13:42:25.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12122" PostTypeId="2" ParentId="12117" CreationDate="2015-01-28T15:11:16.343" Score="27" Body="&lt;p&gt;Turbulence can be quantitatively expressed as Eddy Dissipation Rate (EDR). EDR can be calculated from available onboard measurements, however it is not yet common for aircraft to have software to calculate the EDR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally it was thought to have &lt;a href=&quot;http://adsb.tc.faa.gov/WG3_Meetings/Meeting30/1090-WP30-11-Wake_Vortex%20Appendix%20v8.pdf&quot;&gt;EDR reported over ADS-B&lt;/a&gt;, but it did not become a part of the current specifications. It might be in the next ADS-B version. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120000925.pdf&quot;&gt;NASA Langley paper&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;ftp://www.wmo.ch/Documents/www/amdar/presentations/Turb_Workshop/AMDAR_Panel_Cornman.pdf&quot;&gt;World Meteorological Organization (WMO) presentation&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-01-28T15:11:16.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12123" PostTypeId="2" ParentId="12056" CreationDate="2015-01-28T15:38:29.727" Score="4" Body="&lt;p&gt;Our club found that with a good quantity of combined ice/snow (I don't remember how much) our Cessna 172 tipped onto the tail.  The Piper Warrior did not for whatever reason.  Perhaps wise to add some weight forward of the main gear when parked out in those conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only damage caused on the Cessna (there was none on the Piper) was a broken tailcone as the airplane had the misfortune to have the tailcone snag the edge of the tire tiedown point marker as it tipped back...  If the airplane had not been parked straight, it looks like it just would have been sitting on the rear tie-down hook instead (as a side note, it's common to see scraped tie-down hooks on flight school airplanes from excessive tail-down attitude during takeoff/landing, yet the tailcones don't ever seem to get damaged) and the tailcone would have survived.&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2015-01-28T15:38:29.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12124" PostTypeId="2" ParentId="12108" CreationDate="2015-01-28T16:11:52.777" Score="6" Body="&lt;p&gt;Induction ice can be a problem for jet engines. Other answers have explained how the ice forms. The air expands and cools in the inlet before entering the engine. The first stages of the compressor do not compress the air enough yet to warm it enough to prevent ice from forming. Low power settings can also make it easier for ice to form. Certain atmospheric conditions make ice more likely to form.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA released &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-147.pdf&quot;&gt;AC 20-147&lt;/a&gt;, which &quot;provides guidance and acceptable methods, but not the only methods, for demonstrating compliance with the applicable engine induction system icing and engine ice ingestion requirements.&quot; This describes different types of icing, and the effects it can have on engines. It also describes how engines should be tested to conform to the regulations for these conditions. Ice can form in various places:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The fan or compressor blades themselves&lt;/li&gt;&#xA;&lt;li&gt;Vanes&lt;/li&gt;&#xA;&lt;li&gt;Sensors&lt;/li&gt;&#xA;&lt;li&gt;Bleed ducts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This ice can cause various problems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The ice can come off and damage engine components downstream&lt;/li&gt;&#xA;&lt;li&gt;The ice will reduce the effectiveness of blades, making it harder for the engine to compress the air&lt;/li&gt;&#xA;&lt;li&gt;The ice can impede the flow of air in the engine&lt;/li&gt;&#xA;&lt;li&gt;The ice can block sensors, preventing the control system from correctly monitoring the engine, which can lead to power loss or instability&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One form of icing that has been an issue lately is ice crystal icing. This is caused by small ice crystals in the upper atmosphere, particularly above convective clouds. &lt;a href=&quot;http://ad.easa.europa.eu/ad/US-2013-24-01&quot;&gt;The FAA has issued an AD (Airworthiness Directive) recently about this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This type of icing does not appear on radar due to its low reflectivity, and neither the airplane ice detector nor visual indications reliably indicate the presence of icing conditions. Therefore, it is often undetected by the flight crew. Flight in these conditions can cause ice crystals to accumulate in the core gas flow path of the engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There were previous events on GE CF6-80 engines (used on 747, 767, A310, A330, and others) that the FAA looked into.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the events leading to those prior ADs, the ice has shed during throttle transients and in the descent phase of flight, causing temporary thrust loss.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, there have been &lt;a href=&quot;http://aviationweek.com/commercial-aviation/growing-genx-ice-core-problems-prompt-advisory&quot;&gt;incidents with the newer GEnx engines on 747-8 and 787 aircraft&lt;/a&gt; which have been more serious.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The new events that prompted this AD, however, have occurred during the cruise phase of flight and caused permanent damage (beyond maintenance manual limits) to the engine compressor. In all thrust loss events, data indicate that ice crystals entered and collected in the initial stages of the compressor. Engine temperature data indicate small ice accretions were shed through the core of the engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The engine manufacturers are working to resolve the issues on the aircraft currently affected, and in the meantime &lt;a href=&quot;http://www.skybrary.aero/index.php/Avoidance_of_High_Altitude_Ice_Crystal_Icing_Conditions_-_FAA_Airworthiness_Directive,_No_2013-24-01_-_Potential_Implications_for_ATC&quot;&gt;flight crews are advised&lt;/a&gt; to avoid weather conditions where ice crystals tend to form.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;More definitively, the AD includes immediate mitigating procedures for the affected aircraft which prohibit flight within 50nm of amber and red radar returns that are displayed below the aircraft’s flight path during operations at or above 30,000 ft, when approaching, or in, IMC or visible moisture.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note: Boeing has also published an updated Flight Crew Operations Manual Bulletin with specific operating procedures for flight crews. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-01-28T16:11:52.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12125" PostTypeId="1" AcceptedAnswerId="12158" CreationDate="2015-01-29T01:01:29.870" Score="4" ViewCount="2519" Body="&lt;p&gt;From what I read in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_131&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.31&lt;/a&gt; it never mentions type rating requirements for rotorcraft or helicopters. I Googled online but most of the results showed up for Australia, Canada and the UK. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am starting to believe that the US does not require a pilot to have a type rating for a Robinson &lt;a href=&quot;http://en.wikipedia.org/wiki/Robinson_R22&quot; rel=&quot;nofollow&quot;&gt;R22&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Robinson_R44&quot; rel=&quot;nofollow&quot;&gt;R44&lt;/a&gt; helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I correct that unless the FAA has made a type certificate for that helicopter it does not require a type rating? Would it just require a checkout from wherever you are going to rent?&lt;/p&gt;&#xA;" OwnerUserId="7027" LastEditorUserId="62" LastEditDate="2015-01-29T15:43:58.430" LastActivityDate="2015-01-30T00:52:08.397" Title="Do small helicopters like the R44 require an FAA type rating?" Tags="&lt;faa-regulations&gt;&lt;helicopter&gt;&lt;pilot-certification&gt;&lt;robinson-r44&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12126" PostTypeId="2" ParentId="11696" CreationDate="2015-01-29T02:38:40.950" Score="3" Body="&lt;p&gt;As Simon alluded, the aircraft's speed (example given Mach 1, approx. 340 m/s) is basically one-millionth the speed of the radar energy (traveling at near-light speed, or 300,000,000 m/s).  It's a non-factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, if you want to radar detect something (water droplets, for instance), the detected object needs to be bigger than one quarter-wavelength of the signal you are bouncing against it.  This alone dictates that the weather radar should operate in the microwave range, typically 8-12 GHz (quarter-wavelength approx. 6-10mm) for most systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar signals are sent out in pulses a few μs wide.  The pulse frequency is determined by how far out you are scanning.  More distant weather requires a longer &quot;wait&quot; time before a second pulse is sent out.  For instance, a pulse detecting weather 5km out will return about 35μs later (10000m round trip divided by the speed of light), but typically systems scan much further.  100Hz (pulses per second) pulse repetition frequency is not uncommon (i.e. every 10ms).  This is good enough to provide &lt;em&gt;location&lt;/em&gt; only.  Pulse-Doppler radars provide an understanding of object &lt;em&gt;movement&lt;/em&gt; (i.e. wind speed and direction) as well as &lt;em&gt;location&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We also need to take into account the antenna scan time.  Because the radar signal only returns objects directly in front of the where the antenna is pointing, the antenna needs to be moved around so as to pick up a greater area, and so the scan time is largely affected by the scan pattern.  (Aircraft pitch/roll is also accounted for by most weather radar systems, though depending on the gyros, it is not uncommon for the radar to paint the ground momentarily during a maneuver.)  The &lt;a href=&quot;http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/BA_brochures-documents/RDR_2000_and_2100_Weather_Radar.pdf&quot; rel=&quot;nofollow&quot;&gt;Honeywell RDR 2100&lt;/a&gt; takes 3-4 whole seconds to perform a full left-to-right scan (typically 90 degrees or more).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scan time is also affected by the beam width.  Smaller antennas cannot focus as well as larger antennas, and so will produce a larger beam width, requiring fewer scans to produce a complete picture, at the expense of resolution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transferring all this weather data around takes additional time.  Commercial aircraft systems do this over an ARINC 708 data bus at 1mbit/s.  Range data, intensity, antenna azimuth/elevation, transmitter gain, information is all sent to be processed and displayed.  Higher resolutions will take longer to &quot;paint&quot; the screen than lower resolutions.  The actual data transfer time and display processing time is negligible, because your cockpit indicator might only have a refresh rate of around 60Hz, or a full screen update every 17ms, with a pixel response time less than 5ms.  For reference, this is the same refresh rate as a typical flat screen TV.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All told, from the time a radar pulse is sent out, detects weather, returns, is processed, and displayed on the screen, the time elapsed is typically no better than a half second, and typically longer.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-01-29T03:51:15.230" LastActivityDate="2015-01-29T03:51:15.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12129" PostTypeId="1" CreationDate="2015-01-29T09:00:25.033" Score="2" ViewCount="612" Body="&lt;p&gt;My question is how can the angle of attack be changed when the wing is in the slipstream of a propeller, giving &quot;enough air flow&quot; to the wing. The propeller sends the flow of air in the same direction related to the wing no matter how the aeroplane is oriented in the space. So theoretically the angle of attack should never change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UPD: The answer should not depend on how the plane is thrusted. Turbo engines are also pushing the plane in the same direction related to the fixed wing. ( I am not talking about engines that can change the vector of thrust).&lt;/p&gt;&#xA;" OwnerUserId="6830" LastEditorUserId="6830" LastEditDate="2015-01-29T09:14:14.253" LastActivityDate="2015-01-29T15:58:16.570" Title="How is the Angle of Attack influenced in the slipstream of a propeller?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12130" PostTypeId="2" ParentId="12129" CreationDate="2015-01-29T09:08:18.047" Score="2" Body="&lt;p&gt;Not all planes have propellers and not all of the wing is behind the propeller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact only a small part of the wing is behind the propeller. The rest will get clean air depending on the attitude (orientation) of the aircraft. The wing is also not perfectly straight behind the propeller either, usually dropping down a bit so there is a positive angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet powered planes generally have their engines away from the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most planes, thrust is surprisingly small compared to the weight, an empty &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380#Specifications&quot; rel=&quot;nofollow&quot;&gt;A380&lt;/a&gt; only has a thrust to weight ratio of 0.47 and most of that thrust will be applied horizontally. So as the plane will sink rapidly should there be no lift from the wings. That sink tendency is what provides the angle of attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will max out the sink rate should the wings be level, angle them up a bit and the plane will try to climb.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-29T09:27:10.827" LastActivityDate="2015-01-29T09:27:10.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12131" PostTypeId="1" AcceptedAnswerId="12132" CreationDate="2015-01-29T09:10:41.753" Score="4" ViewCount="641" Body="&lt;p&gt;When an airplane is about to takeoff (after leaving the gate), how should the flight attendants respond to an emergency with a passenger which requires medical immediate assistance?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="65" LastEditDate="2015-01-29T15:07:17.200" LastActivityDate="2015-01-29T18:45:33.253" Title="How can flight attendants respond to an immediate medical emergency?" Tags="&lt;emergency&gt;&lt;airline-operations&gt;&lt;passenger&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12132" PostTypeId="2" ParentId="12131" CreationDate="2015-01-29T09:18:59.777" Score="6" Body="&lt;p&gt;If the pilot knows before committing to take-off and reaching the point of no return then he will abort the takeoff and ask the tower to send an ambulance and stairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If he is committed to take off then he will get into the air and then tell the tower of the emergency; circle around (possibly dump fuel depending on the severity) and land again to get the passenger off board on the ambulance waiting near the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether the plane can then top up the tanks and take off again will depend on whether the landing was overweight or not. If it was then the plane needs to be inspected before it can be put back into use and the other passengers will need to leave the plane and wait until the next plane can ferry them on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin crew will apply first aid until the ambulance crew can take the sick passenger.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-29T18:45:33.253" LastActivityDate="2015-01-29T18:45:33.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12133" PostTypeId="1" AcceptedAnswerId="12139" CreationDate="2015-01-29T09:20:10.320" Score="3" ViewCount="676" Body="&lt;p&gt;When black-boxes are found, how is the information retrieved from within the data storage?  Is there a special kind of device used for this? &lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="572" LastEditDate="2015-01-29T13:30:32.843" LastActivityDate="2015-01-29T23:47:17.140" Title="How do airlines (or the government) retrieve information from the black box of an aircraft?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12134" PostTypeId="1" AcceptedAnswerId="12138" CreationDate="2015-01-29T09:28:00.177" Score="3" ViewCount="1772" Body="&lt;p&gt;Black boxes contain the information regarding to a flight. What is the form of those information? Any particular language log?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="19" LastEditDate="2016-11-15T14:34:15.533" LastActivityDate="2019-03-14T00:15:25.960" Title="What is the form of information stored in black box?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12135" PostTypeId="1" AcceptedAnswerId="12136" CreationDate="2015-01-29T09:33:10.550" Score="-5" ViewCount="503" Body="&lt;p&gt;I'd never took long flights, however curios if one day I'll fly to NewYork from India and I wish to eat my favourite dish, which may not available in kitchen of my flight, what they will do? Is there something that I've to choose from the menu only? If so, I ordered one from the menu and its not available there? However I will force air hostess to get that particular dish for me, what can be done in this situation?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastActivityDate="2015-01-29T09:40:05.927" Title="What if a passenger forcefully requested for a food which is not available on the flight?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-01-29T13:14:07.840" ContentLicense="CC BY-SA 3.0" />
  <row Id="12136" PostTypeId="2" ParentId="12135" CreationDate="2015-01-29T09:40:05.927" Score="5" Body="&lt;p&gt;There is only so much food on the plane while it's in the air. If the dish is not available then &lt;em&gt;it is not available&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should you then throw a tantrum and the flight-attendant judges that you are a danger to themselves or other passengers or the continued flight; the pilot will then divert the flight and throw you off at the nearest available airport. After that you may be fined for the trouble you gave them.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-29T09:40:05.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12138" PostTypeId="2" ParentId="12134" CreationDate="2015-01-29T09:55:21.943" Score="3" Body="&lt;p&gt;There are 2 different black boxes. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The cockpit voice recorder. This holds audio from several different sources, including the microphone for each pilot, the radio and a general cockpit microphone.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The flight data recorder holds at least 88 different parameters including attitude of the craft, engine performance, autopilot setting, pilot input one the controls, etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-29T09:55:21.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12139" PostTypeId="2" ParentId="12133" CreationDate="2015-01-29T09:57:11.843" Score="3" Body="&lt;p&gt;They send it to the manufacturer (or other lab) who knows how to get the data out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Old black boxes stored the data on tape which they take out put in a reader and print out the data. Partially damaged tape can still be read, the result will be a data stream with holes in it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newer black boxes use solid state storage (like one of those 8gig memory cards). It will be put in a reader to read it out. The exact format of the data will be specific per manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then the analysts will make nice graphs of it for the investigators. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-29T09:57:11.843" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12140" PostTypeId="1" AcceptedAnswerId="12154" CreationDate="2015-01-29T10:18:50.420" Score="2" ViewCount="9306" Body="&lt;p&gt;Are there any cameras inside a plane to watch out the activities of passengers?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="1467" LastEditDate="2015-01-29T10:27:25.140" LastActivityDate="2015-01-29T15:12:38.927" Title="Are there any cameras inside a plane?" Tags="&lt;airliner&gt;&lt;security&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-01-29T19:27:40.323" ContentLicense="CC BY-SA 3.0" />
  <row Id="12141" PostTypeId="1" AcceptedAnswerId="12152" CreationDate="2015-01-29T10:36:46.880" Score="9" ViewCount="10797" Body="&lt;p&gt;When the static ports are blocked, pilots use the alternative static soure and it measures the static pressure inside the cockpit. And it is said that the static pressure inside is lower than the outside static pressure. I wonder why does this happen? Because you know cockpit is blocked from outside and how does the venturi effect applied inside the cockpit and static pressure inside?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="572" LastEditDate="2015-01-29T13:32:35.790" LastActivityDate="2015-02-03T00:26:47.100" Title="Why does the static pressure inside the cockpit vary from outside static pressure?" Tags="&lt;aircraft-design&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12142" PostTypeId="1" AcceptedAnswerId="12144" CreationDate="2015-01-29T11:05:54.287" Score="1" ViewCount="1888" Body="&lt;p&gt;An aircraft is flying in cruise flight on a long distance flight. The autopilot is turned off. The only occupant of the aircraft is the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suddenly that pilot dies, what will happen?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="65" LastEditDate="2015-01-29T14:31:32.190" LastActivityDate="2016-05-26T13:18:49.697" Title="What would happen if the sole pilot dies while flying an aircraft?" Tags="&lt;emergency&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ClosedDate="2015-01-29T15:32:02.297" ContentLicense="CC BY-SA 3.0" />
  <row Id="12143" PostTypeId="1" CreationDate="2015-01-29T11:08:04.837" Score="25" ViewCount="38515" Body="&lt;p&gt;Is there an aerodynamic reason why the concept of biplane or triplane has been completely abandoned? Practically all planes were biplanes in WW1, and in WW2 practically none were developed.&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2020-10-13T06:59:37.283" Title="Why are there no longer any biplanes?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12144" PostTypeId="2" ParentId="12142" CreationDate="2015-01-29T11:21:12.150" Score="15" Body="&lt;p&gt;It has happened &lt;a href=&quot;http://www.pilotfriend.com/aeromed/medical/uncon_landing.htm&quot;&gt;before that the single pilot lost consciousness while flying.&lt;/a&gt; What then happened is that the plane just went on until out of fuel after which it will glide down and skid to a stop (pilot survived). This is assuming there is no obstacle in the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cornfield_Bomber&quot;&gt;cornfield bomber&lt;/a&gt;, a fighter pilot eject and the plane still under power just kept going in a straight line and &quot;landed&quot; in a field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more deadly example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot;&gt;helios flight 522&lt;/a&gt;. A mistake in the pressure regulation setting let the plane become unpressurized while climbing to cruise altitude. Both pilots lost consciousness and the plane's autopilot followed its programmed path following the waypoints and ending up in a holding patter until it ran out of fuel and crashed into the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Survival depends on luck with obstacles, whether the plane is properly trimmed and which order the engines flame out in, asymmetric flame-out may result in a spin.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-29T14:08:07.773" LastActivityDate="2015-01-29T14:08:07.773" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12146" PostTypeId="2" ParentId="12142" CreationDate="2015-01-29T12:04:25.373" Score="0" Body="&lt;p&gt;&lt;em&gt;Assuming no autopilot&lt;/em&gt; the plane will likely crash very soon as even if the airframe was trimmed at the time of pilot's death as there will be no mechanism correcting trimming on outer forces changes (turbulence, pressure change, etc.) Imagine a driver dying in a car - if the road is straight and wide, the car may go on for a while but as soon as there is just a small change in roads direction, uneven surface or even stronger wind, the car will crash quickly. Some planes may have features not directly tied to autopilot that correct piloting mistakes to some extent which may prolong the planes survival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also very important is what happens with the pilot's body. As long as the body doesn't interfere with plane controls, the plane will likely go forward longer. If, on the other hand, the pilot's body say falls on the controls, it may even disengage the autopilot if present and force the plane to make a move that will eventually go over its physical limits and results in spiral, stall, dive or disintegration in the air.&lt;/p&gt;&#xA;" OwnerUserId="7033" LastEditorUserId="7033" LastEditDate="2016-05-26T13:18:49.697" LastActivityDate="2016-05-26T13:18:49.697" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12148" PostTypeId="2" ParentId="12143" CreationDate="2015-01-29T12:12:50.847" Score="36" Body="&lt;p&gt;&lt;strong&gt;Firstly, there are:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wacoaircraft.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;For example this company currently makes a biplane&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;But the &lt;strong&gt;main reason&lt;/strong&gt; is that they're inefficient, and don't really do much that a monoplane can't.&lt;/p&gt;&#xA;&lt;p&gt;They produce a lot of drag compared to the amount of lift they produce, meaning they use a lot of fuel to travel the same distance. They have fairly poor visibility, which is usually considered a bad thing!&lt;/p&gt;&#xA;&lt;p&gt;They do have a few advantages - they have a good roll rate, making them quite maneuverable, and they have a very low stall speed and can fly on little power, meaning they can fly slowly very well (where their increased drag doesn't make much difference: drag increases with the &lt;strong&gt;square&lt;/strong&gt; of airspeed)&lt;/p&gt;&#xA;&lt;p&gt;Overall, though, the above makes them suited only to aerobatics, which can also be performed by monoplanes. Advances in wing design and composite materials take away most of the advantages of a biplane for any other use: ie actually travelling (the main purpose of an aeroplane) and carrying a load.&lt;/p&gt;&#xA;&lt;p&gt;Overall, then, they're more complex than a monoplane, less efficient, and aren't much more manoeuverable. They have more disadvantages than advantages.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Biplanes were popular in WWI&lt;/strong&gt; not because of any inherent advantage, but simply because technology hadn't advanced far enough to allow any other options. Once the monoplane was properly developed, it allowed &lt;strong&gt;much&lt;/strong&gt; higher speeds (450mph for a late WWII fighter, 300mph for an Early WWII fighter, compared to around 120 mph for a late WWI fighter). High speed fighters beat low speed fighters (at least before stealth technology and guided missiles)&lt;/p&gt;&#xA;&lt;p&gt;There &lt;strong&gt;were&lt;/strong&gt; a few leftover biplanes in WWII - The Fairey Swordfish torpedo bomber was one of the most widely used, as the low speed and good lift from the biplane design allowed it to carry a heavy torpedo, while the drag issues didn't matter at the slow speeds they needed to fly to be able to release the torpedo properly and on target. Others were the Gloster Gladiator (UK), Fiat CR.42 (Italy) and Polikarpov I-15 (Soviet Union) which achieved varying levels of success in the early stages, but were well and truly outclassed when facing even early-war monoplanes.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9981/what-special-handling-characteristics-or-techniques-do-biplanes-have?lq=1&quot;&gt;This answer on a similar question&lt;/a&gt; gives some useful context about the direct advantages and disadvantages. It doesn't directly explain why biplanes fell out of favour, but it may help understand my own answer here.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="1405" LastEditDate="2020-10-13T06:59:37.283" LastActivityDate="2020-10-13T06:59:37.283" CommentCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="12149" PostTypeId="1" AcceptedAnswerId="12153" CreationDate="2015-01-29T12:24:39.263" Score="13" ViewCount="69485" Body="&lt;p&gt;Does a plane have brakes to stop or slow down while flying?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if the pilots see a large flock of birds at some distance in front of the airplane, and they want to reduce speed suddenly. What will happen if an airplane doesn't have such brake?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="97" LastEditDate="2015-01-30T18:29:56.797" LastActivityDate="2017-01-07T21:25:18.923" Title="Does a plane have brakes to stop or slow down while flying?" Tags="&lt;flight-controls&gt;&lt;airspeed&gt;&lt;braking&gt;" AnswerCount="9" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12150" PostTypeId="2" ParentId="12149" CreationDate="2015-01-29T12:30:04.487" Score="11" Body="&lt;p&gt;No a plane doesn't stop in midair, planes need to keep moving forward to remain in the air (unless they are VTOL capable). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it can do is simply turn around or go over/under the obstruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;noreferrer&quot;&gt;VTOL&lt;/a&gt; means vertical takeoff and landing. It essentially means they can hover in place like a helicopter.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-30T09:33:42.283" LastActivityDate="2015-01-30T09:33:42.283" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12151" PostTypeId="2" ParentId="11332" CreationDate="2015-01-29T13:07:03.743" Score="6" Body="&lt;p&gt;A new pair of 747-8s are &lt;a href=&quot;http://www.usnews.com/news/blogs/ken-walshs-washington/2015/01/29/pentagon-selects-a-new-air-force-one&quot; rel=&quot;nofollow&quot;&gt;planned to come in the next five years&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The &lt;strong&gt;Boeing 747-8&lt;/strong&gt; is the only aircraft manufactured in the United States [that] when fully missionized meets the necessary capabilities established to execute the presidential support mission,&quot; said Air Force Secretary Deborah James in a news release. The contract must still be negotiated. The cost was not disclosed but the Wall Street Journal estimated that the pricetag could be $1.65 billion for two replacement 747s.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The current four-engine 747 and its backup are 25 years old, and Air Force officials consider the aircraft's normal life span to be 30 years. The new planes – a primary and a backup – are supposed to be ready in five years, James said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is information straight &lt;a href=&quot;http://www.af.mil/News/ArticleDisplay/tabid/223/Article/562748/af-identifies-boeing-747-8-platform-for-next-air-force-one.aspx&quot; rel=&quot;nofollow&quot;&gt;from the U.S. Airforce&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Analyses of the capability requirements conclude a four-engine, wide body aircraft is required to meet the needs of the Air Force One mission. Market research determined there are two four-engine platforms that could meet the requirements; the 747-8 manufactured by Boeing in the state of Washington, and the A380 manufactured by Airbus in Toulouse, France.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The decision, made official through a Determinations and Findings document, authorizes the commercial aircraft purchase by other than full and open competition. This decision, in conjunction with the notification of the Air Force’s intent to award a sole source contract to Boeing for the modification of the 747-8, allows discussions with Boeing that will likely lead to a contract for the aircraft platform as well as the modifications necessary to missionize the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, supposedly &lt;a href=&quot;https://web.archive.org/web/20141015010524/http://www.bizjournals.com/seattle/news/2014/08/12/will-u-s-copy-japan-and-switch-to-777-for-air.html?page=all&quot; rel=&quot;nofollow&quot;&gt;B777 was also considered&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6805" LastEditorUserId="6805" LastEditDate="2016-07-29T09:49:06.083" LastActivityDate="2016-07-29T09:49:06.083" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12152" PostTypeId="2" ParentId="12141" CreationDate="2015-01-29T13:14:35.797" Score="10" Body="&lt;p&gt;You're referring to this statement in the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilots Handbook of Aeronautical Knowledge, Page 7-12&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some aircraft are equipped with an alternate static source in the&#xA;  flight deck. In the case of a blocked static source, opening the&#xA;  alternate static source introduces static pressure from the flight&#xA;  deck back into the system. Flight deck static pressure is lower than&#xA;  outside static pressure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The reason for this error with alternate static source is that the air flowing around the airframe creates a slight vacuum inside the airframe, thereby lowering the barometric pressure and generating erroneous readings in the pitot-static system.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-01-31T15:18:24.530" LastActivityDate="2015-01-31T15:18:24.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12153" PostTypeId="2" ParentId="12149" CreationDate="2015-01-29T13:29:21.380" Score="40" Body="&lt;p&gt;An airplane can slow down and reduce its speed while in flight. The easiest way to do so is to reduce the amount of thrust that the engines are producing. This will produce an almost immediate reduction of the airspeed, especially if the plane is maintaining the same altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also devices called &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_brake_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;air brakes&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Spoiler_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;spoilers&lt;/a&gt; that can be further used to reduce speed. These, however, are never&lt;sup&gt;1&lt;/sup&gt; used in normal, level flight by passenger&lt;sup&gt;2&lt;/sup&gt; aircraft and are normally only used to reduce speed during the descent and landing phases of the aircraft&lt;sup&gt;3&lt;/sup&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airplane reduces its speed too much, it will of course stall and start dropping precipitously, at which time the airspeed usually also increases again. The slowest speed an aircraft can maintain at a given altitude without stalling is listed in its &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_envelope&quot; rel=&quot;noreferrer&quot;&gt;flight envelope.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in the scenario you mentioned (obstacles ahead), it's usually easiest to simply fly around the obstacle.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;a href=&quot;https://aviation.stackexchange.com/questions/12149/does-a-plane-have-brakes-to-stop-or-slow-down-while-flying/12153#comment24649_12153&quot;&gt;Never say never on the internet.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;: The situation is different in military aircrafts, you can see the approaching Su-27 using its airbrake in &lt;a href=&quot;http://www.youtube.com/watch?v=A-rkAnGqMOI&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;: The wheels of most aircraft also have brakes, similar to those found on automobiles. Obviously these can only be used when the plane is touching the ground. Lowering retracted landing gear will also increase drag. There are also &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_reversal&quot; rel=&quot;noreferrer&quot;&gt;thrust reversers&lt;/a&gt; on some aircraft that are used in the final stages of landing. Use of thrust reversers during flight can be &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;noreferrer&quot;&gt;disastrous&lt;/a&gt; although some older aircraft (including the C-17A) were designed to use thrust reversal to scrub speed in-flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, some gliders and larger aircraft have &lt;a href=&quot;https://en.wikipedia.org/wiki/Drogue_parachute&quot; rel=&quot;noreferrer&quot;&gt;drag or drogue parachutes&lt;/a&gt; to help slow them down, for example for use on short runways.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-07-10T23:50:27.083" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12154" PostTypeId="2" ParentId="12140" CreationDate="2015-01-29T14:50:54.567" Score="4" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.l-3ar.com/PDF_Files/MKT030.pdf&quot; rel=&quot;nofollow&quot;&gt;AIRCRAFT CABIN SURVEILLANCE SYSTEM&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.google.com/patents/US6864805&quot; rel=&quot;nofollow&quot;&gt;Surveillance system for aircraft interior&lt;/a&gt; (2002)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/779947&quot; rel=&quot;nofollow&quot;&gt;Surveillance Cameras In Aircraft Cabins&lt;/a&gt; (2002)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;JetBlue Airways is the first U.S. carrier to get approval from the Federal Aviation Administration to install video cameras on all its airplanes. &#xA;  JetBlue is a successful start-up carrier based at New York's John F. International Kennedy airport. Soon after the Sept. 11 hijackings, the airline installed bullet-proof cockpit doors on all its planes. And it was the first carrier to match all luggage to passengers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The airline has outfitted one plane with the video surveillance system, and plans to have its 23 other jets equipped with the miniature cameras within the next few months. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The cameras are positioned to cover the entire cabin. Some are visible, others are hidden so they cannot be tampered with&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.newscientist.com/article/dn14013-inflight-surveillance-could-foil-terrorists-in-the-sky.html&quot; rel=&quot;nofollow&quot;&gt;In-flight surveillance could foil terrorists in the sky&lt;/a&gt; (2008)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The European Union's Security of Aircraft in the Future European Environment (SAFEE) project uses a camera in every passenger's seat, with six wide-angle cameras to survey the aisles. Software then analyses the footage to detect developing terrorist activity or &quot;air-rage&quot; incidents, by tracking passengers' facial expressions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aircraftinteriorsinternational.com/news.php?NewsID=11709&quot; rel=&quot;nofollow&quot;&gt;A350 cabin surveillance contract&lt;/a&gt; (2012/2013?)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;KID-Systeme has been selected to supply cabin surveillance equipment for the Airbus A350 XWB family of aircraft. The integrated solution will include both a cockpit door surveillance system (CDSS) and a cabin video monitoring system (CVMS).&#xA;  The CDSS provides pilots with a clear view of anyone in the area of the cockpit door, enabling them to take the appropriate action when entry to the cockpit is requested. The CVMS allows both the pilots and the cabin crew to view passengers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-01-29T15:12:38.927" LastActivityDate="2015-01-29T15:12:38.927" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12155" PostTypeId="2" ParentId="12149" CreationDate="2015-01-29T15:36:28.797" Score="2" Body="&lt;p&gt;There are &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/forces.html&quot; rel=&quot;nofollow&quot;&gt;4 forces&lt;/a&gt; that act on a plane: &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/forces.html&quot; rel=&quot;nofollow&quot;&gt;thrust, drag, lift, and weight&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes slow down because of drag.  Once power is reduced, drag is greater than thrust and causes the plane to slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry, I'm pretty new here and probably didn't include enough information in my original answer so here's a more thorough answer from the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In steady flight, the sum of these opposing forces is always zero.&#xA;  There can be no unbalanced forces in steady, straight flight based&#xA;  upon Newton’s Third Law, which states that for every action or force&#xA;  there is an equal, but opposite, reaction or force. This is true&#xA;  whether flying level or when climbing or descending. It does not mean&#xA;  the four forces are equal. It means the opposing forces are equal to,&#xA;  and thereby cancel, the effects of each other. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For an aircraft to move, thrust must be exerted and be greater than&#xA;  drag. The aircraft will continue to move and gain speed until thrust&#xA;  and drag are equal. In order to maintain a constant airspeed, thrust&#xA;  and drag must remain equal, just as lift and weight must be equal to&#xA;  maintain a constant altitude. &lt;strong&gt;If in level flight, the engine power is&#xA;  reduced, the thrust is lessened, and the aircraft slows down. As long&#xA;  as the thrust is less than the drag, the aircraft continues to&#xA;  decelerate until its airspeed is insufficient to support it in the&#xA;  air.&lt;/strong&gt; Likewise, if the engine power is increased, thrust becomes&#xA;  greater than drag and the airspeed increases. As long as the thrust&#xA;  continues to be greater than the drag, the aircraft continues to&#xA;  accelerate. When drag equals thrust, the aircraft flies at a constant&#xA;  airspeed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7038" LastEditorUserId="-1" LastEditDate="2015-02-02T15:42:08.323" LastActivityDate="2015-02-02T15:42:08.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12156" PostTypeId="2" ParentId="12149" CreationDate="2015-01-29T15:36:39.233" Score="13" Body="&lt;p&gt;You can also &quot;crab&quot;, which is the extreme opposite of being in &quot;trim&quot;. Essentially, you turn the ailerons opposite the rudder and keep the nose down so it doesn't stall. The plane ends up going thru the air diagonally, presenting one side of the body to the air. That produces a &lt;em&gt;lot&lt;/em&gt; of drag. It is a great way to lose altitude quickly in a small plane. It's normally done at low speed, and feels strange to passengers. Best to go gently at higher speeds. Too much exuberance might stress a weak airframe.&lt;/p&gt;&#xA;" OwnerUserId="7039" LastActivityDate="2015-01-29T15:36:39.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12157" PostTypeId="1" AcceptedAnswerId="12159" CreationDate="2015-01-29T15:39:19.153" Score="4" ViewCount="375" Body="&lt;p&gt;I'm wondering how accurate the location information displayed on the in-flight entertainment system is. As I recall, it always shows quite direct routes, such as this:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/OIhee.jpg&quot; alt=&quot;Inflight location&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I'm wondering how accurate this information is. I can image that because of ATC the route will not be as smooth as displayed above. Does it simply show a predetermined route as function of time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More towards a specific case, would the people onboard the Malaysia Airlines MH370 be able to see the changed course of the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-01-29T16:01:31.713" Title="How accurate is the inflight location information?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12158" PostTypeId="2" ParentId="12125" CreationDate="2015-01-29T15:39:30.803" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#ap14.2.61.1&quot; rel=&quot;noreferrer&quot;&gt;SFAR 73&lt;/a&gt; is &lt;em&gt;Robinson R-22/R-44 Special Training and Experience Requirements&lt;/em&gt; and lists the specific training requirements for that model. Here's one relevant piece:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) No person may act as pilot in command of a Robinson model R-22&#xA;  unless that person:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Has had at least 200 flight hours in helicopters, at least 50&#xA;  flight hours of which were in the Robinson R-22; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Has had at least 10 hours dual instruction in the Robinson R-22&#xA;  and has received an endorsement from a certified flight instructor&#xA;  authorized under paragraph (b)(5) of this section that the individual&#xA;  has been given the training required by this paragraph and is&#xA;  proficient to act as pilot in command of an R-22. Beginning 12&#xA;  calendar months after the date of the endorsement, the individual may&#xA;  not act as pilot in command unless the individual has completed a&#xA;  flight review in an R-22 within the preceding 12 calendar months and&#xA;  obtained an endorsement for that flight review. The dual instruction&#xA;  must include at least the following abnormal and emergency procedures&#xA;  flight training: [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#ap14.2.91.8&quot; rel=&quot;noreferrer&quot;&gt;SFAR 108&lt;/a&gt; has similar requirements for operating the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mitsubishi_MU-2&quot; rel=&quot;noreferrer&quot;&gt;Mitsubishi MU-2B&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, note that the &lt;em&gt;type certificate&lt;/em&gt; is for the aircraft, and has nothing to do with whether an individual pilot is qualified to fly it or not.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-01-29T21:13:13.443" LastActivityDate="2015-01-29T21:13:13.443" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12159" PostTypeId="2" ParentId="12157" CreationDate="2015-01-29T15:50:46.550" Score="4" Body="&lt;p&gt;The route is actually quite accurate; it is derived from the navigation system of the aircraft. You can determine your departure and arrival routes pretty well from the inflight entertainment system if you are familiar with the routes on the airport you are flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the image in your question you can see a slight course change East of Newfoundland. This is where the aircraft entered its oceanic track. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the system was operating on MH370, it would have shown the course change as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see what the IFE showed on 11 september 2001 when aircraft heading towards the USA were not allowed into US airspace after the attacks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/0188150/L&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TbLC4.jpg&quot; alt=&quot;9/11 IFE photo from Airliners.net, copyright Michiel Jas&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://www.airliners.net/photo/0188150/L&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-01-29T16:01:31.713" LastActivityDate="2015-01-29T16:01:31.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12160" PostTypeId="2" ParentId="12157" CreationDate="2015-01-29T15:50:59.383" Score="1" Body="&lt;p&gt;The position should be fairly accurate, as it is probably taking from some of the airplane's navigation systems. Even if it isn't, the image you posted can't be expected to be accurate to more than +/-100 miles or so, due to the map scale and size of the airplane icon. But at closer zoom levels, you can see the accuracy is much better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's certainly possible that the system uses the pre-programmed flight route and estimates the position based on time. But especially on a long flight such as this one, conditions enroute like winds could significantly change the flight time, enough that it would be obvious that the location was wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes generally will fly as direct as possible, since that would be the route that requires the least time and fuel. However, winds or significant weather may require the plane to change its path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the picture you posted, you can see a slight turn to the right over Newfoundland as the plane is entering the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot; rel=&quot;nofollow noreferrer&quot;&gt;North Atlantic Track&lt;/a&gt; it is following for this flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the MH370 plane had this equipment, and it wasn't somehow disabled, then yes, the passengers would have seen the real location of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/questions/9270/offline-airplane-route-software/9299&quot;&gt;another question&lt;/a&gt; regarding this display.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-01-29T15:50:59.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12161" PostTypeId="2" ParentId="12129" CreationDate="2015-01-29T15:58:16.570" Score="0" Body="&lt;p&gt;The angle of attack, in relation to a propeller, probably affects yaw more than anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way a plane is thrusted, propeller vs jets, significantly changes the dynamics of how the plane flies.  Because of propeller torque and p-factor the plane tends to yaw more and will require more rudder input to compensate, especially as angle of attack is increased (on take off for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow&quot;&gt;Look at this link to P-factor for more information.&lt;/a&gt;  Here's an excerpt:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;P-factor, also known as asymmetric blade effect and asymmetric disc&#xA;  effect, is an aerodynamic phenomenon experienced by a &lt;strong&gt;moving&#xA;  propeller&lt;/strong&gt;, that is responsible for asymmetrical relocation of the&#xA;  propeller's center of thrust when aircraft is at a &lt;strong&gt;high angle of&#xA;  attack&lt;/strong&gt;. This shift in the location of the center of thrust will exert&#xA;  a yawing moment on the aircraft, causing it to yaw slightly to one&#xA;  side. &lt;strong&gt;A rudder input is required to counteract the yawing tendency&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7038" LastActivityDate="2015-01-29T15:58:16.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12162" PostTypeId="1" CreationDate="2015-01-29T16:52:40.190" Score="6" ViewCount="39902" Body="&lt;p&gt;In passenger airplane how much thrust is required to takeoff? What factors does it depend on?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="65" LastEditDate="2015-01-29T17:05:03.997" LastActivityDate="2020-11-17T03:42:02.717" Title="What is the minimum thrust needed to takeoff?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;takeoff&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12163" PostTypeId="2" ParentId="12162" CreationDate="2015-01-29T17:05:07.090" Score="2" Body="&lt;p&gt;The amount of thrust necessary is the force required to accelerate the aircraft to take off speed, a speed which allows the wings to generate enough lift to sustain the aircraft in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Factors include&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;aircraft weight&lt;/li&gt;&#xA;&lt;li&gt;runway condition (length, slope, dry/wet)&lt;/li&gt;&#xA;&lt;li&gt;flaps configuration&lt;/li&gt;&#xA;&lt;li&gt;head wind component&lt;/li&gt;&#xA;&lt;li&gt;If it's a multi-engine aircraft, the ability to safely get airborne in the event of a single engine failure is considered as well.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If by &quot;amount of thrust&quot;, you mean the acceleration force: engine power ranges from 160hp on small propeller planes to thousands of pounds in turbine jets (Boeing 777's engine is rated at 417kN). In most GA planes, takeoff power = full power. In larger aircrafts, typically it is slightly below full power to save engine wear.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that &quot;thrust&quot; is not used to get an airplane off the ground. &quot;Lift&quot; is used to get it airborne and counteract the &quot;weight&quot;. &quot;Thrust&quot; is produced by the engine(s) to propel the plane forward, &quot;lift&quot; is created by the wings.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-01-29T17:21:13.270" LastActivityDate="2015-01-29T17:21:13.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12164" PostTypeId="2" ParentId="12149" CreationDate="2015-01-29T17:09:40.743" Score="8" Body="&lt;p&gt;Many jets &amp;amp; gliders have spoilers or airbrakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They  function by adding drag and, in some cases, reducing available lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aircraft descends, speed builds up unless the energy is dissipated in some way. Modern aircraft have fairly clean design which means it takes a while&#xA;to 'bleed' off the energy. This is good for energy efficiency, but is problematic when you need to descend quickly, for example during an approach or flying around significant thermals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propellers often provide a natural speed brake when power is removed and so act as an airbrake, but jets &amp;amp; gliders do not have this option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in other answers, there is a minimum speed below which the aircraft cannot fly, however avoidance of issues such as birds, smoke, etc., is usually performed by change of direction or altitude rather than slowing down.&lt;/p&gt;&#xA;" OwnerUserId="3212" LastActivityDate="2015-01-29T17:09:40.743" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12165" PostTypeId="2" ParentId="12162" CreationDate="2015-01-29T17:11:32.687" Score="9" Body="&lt;p&gt;You need at least enough thrust to keep the airplane flying at the speed of minimum drag. This is quite a bit higher than the minimum flight speed, so you should add something to quicken the acceleration to this point. Also, you want to climb eventually, so you better add some more thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, the static thrust of an airliner is at least a quarter of its weight. If the airliner is empty, this can become as much as half of the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason is altitude capability: Since thrust goes down with the density of air, the static thrust in the cruise altitude is only a quarter of sea level thrust. The thrust of a modern high-bypass-ratio engine drops with speed, so at cruise speed and altitude, thrust is roughly a sixth of sea level static.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second reason is safety: The take-off should be continued even after one engine fails in the late acceleration phase. Now a normally two-engined plane has only half as much thrust available and should still get into the air, so it doesn't crash into whatever follows at the end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust needed to sustain flight is about 1/18 of aircraft weight, and if you factor in the multiples given above, you will notice that if the aircraft can fly at full thrust in cruise, this fits nicely with a static sea level thrust force equivalent to one third of its weight force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The factors for take-off thrust are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Runway length: Short runways need more excess thrust for faster acceleration.&lt;/li&gt;&#xA;&lt;li&gt;Runway elevation: Higher places have less dense air, so more speed is needed to get airborne, and less thrust is available from the engines than at sea level. &lt;/li&gt;&#xA;&lt;li&gt;Runway slope. Taking off downhill is equivalent to having a little extra thrust.&lt;/li&gt;&#xA;&lt;li&gt;Air temperature: Colder air is denser, so minimum speed is lower and the engines develop more thrust.&lt;/li&gt;&#xA;&lt;li&gt;Wind speed: A headwind is equivalent to starting the takeoff run at this speed.&lt;/li&gt;&#xA;&lt;li&gt;Minimum flight speed: A low wing loading and low-drag flap settings reduce the speed at which the aircraft can take off.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-01-29T20:42:49.700" LastActivityDate="2015-01-29T20:42:49.700" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12167" PostTypeId="2" ParentId="11990" CreationDate="2015-01-29T18:55:16.840" Score="0" Body="&lt;p&gt;IMHO Weather is main thing to blame&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many things contribute to an air plane lifting force during a climb; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The plane speed &#xA;Faster speed higher lifting force.&lt;br&gt;&#xA;Remember Winds also makes the plane's speed slower/or faster&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Air density:&#xA;Higher latitude thinner the air : lower lifting force lower&#xA;Storm blow such as in a whirlpool can cause low pressure/thin air space: lower lifting force&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Climb angle:&#xA;Stiffer the angle or &quot;more vertical&quot;: less lifting force;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winds may change directions make climb angle virtually- become more vertically : hence less lifting force&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it still a guess, the plane would be ok if it perform the same climbing in normal weather; however in a violent storm, you couldn't tell what would happen.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it leaves my own question on this matter : If pilot can manually fly the plane, how could he/she trained in such situation ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Something about me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know nothing about airplane neither being pilot, but I know little in physics&lt;/p&gt;&#xA;" OwnerUserId="7044" LastActivityDate="2015-01-29T18:55:16.840" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12169" PostTypeId="2" ParentId="7649" CreationDate="2015-01-29T20:09:37.763" Score="16" Body="&lt;p&gt;&lt;em&gt;I reached out to the &lt;a href=&quot;http://www.cad.gov.hk/english/home.html&quot;&gt;Hong Kong Civil Aviation Department&lt;/a&gt; and asked this question. To my surprise, I got an answer back in less than 12 hours.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of December 31, 2014, they report:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;219 private pilots&lt;/li&gt;&#xA;&lt;li&gt;951 commercial pilots&lt;/li&gt;&#xA;&lt;li&gt;4007 ATPL holders&lt;/li&gt;&#xA;&lt;li&gt;20 MCPL holders&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For a total of 5197 pilots licensed in Hong Kong.&lt;/p&gt;&#xA;" OwnerUserId="7023" LastEditorUserId="64" LastEditDate="2015-01-29T22:22:42.540" LastActivityDate="2015-01-29T22:22:42.540" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12170" PostTypeId="2" ParentId="12117" CreationDate="2015-01-29T20:24:49.510" Score="1" Body="&lt;p&gt;I think you are asking two questions in a single way. I understood that you would like to know firstly is there is a physical unit that could give you quantifyable information about airplane turbulence and, on top, you are asking if, having this unit, is possible to quantify turbulence in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the first one, you already have nice answer about them. You can quantify by using EDR or some other similar units.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the second part of the question, can I actually in flight measure it?, the answer is more complicated. Is possible to measure the turbulence once the airplane is affected by it using its effect on the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, to the question, can I measure the turbulence before airplane flies over it? that's more complicated, and there are some R&amp;amp;T projects trying to investigate LASER based detection both short range and long range (30km). There is an European project called &lt;a href=&quot;http://delicat.inoe.ro/&quot; rel=&quot;nofollow&quot;&gt;DELICAT&lt;/a&gt; working on this topic.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-01-29T20:24:49.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12171" PostTypeId="2" ParentId="12125" CreationDate="2015-01-29T20:51:38.037" Score="6" Body="&lt;p&gt;The FAA does indeed require model-specific type ratings for many aircraft (a list of aircraft which the FAA recognizes type ratings for is &lt;a href=&quot;http://registry.faa.gov/TypeRatings/&quot;&gt;here&lt;/a&gt;). &lt;a href=&quot;http://www.risingup.com/fars/info/part61-31-FAR.shtml&quot;&gt;FAR 61.31&lt;/a&gt; says that type ratings are required for &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Large aircraft (except lighter-than-air).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Turbojet-powered airplanes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Other aircraft specified by the Administrator through aircraft&#xA;  type certificate procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this context, according to &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22886&quot;&gt;Advisory Circular 61-89E&lt;/a&gt;, &quot;large&quot; means it has a gross weight of 12,500 lbs or greater. In addition, based on (2) above, you need a type rating in the US to fly any jet, even small, single-engine jets or those designed specifically for single-pilot operation. &lt;/p&gt;&#xA;" OwnerUserId="7023" LastActivityDate="2015-01-29T20:51:38.037" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12172" PostTypeId="2" ParentId="8380" CreationDate="2015-01-29T21:08:11.313" Score="1" Body="&lt;p&gt;A Google search of &lt;strong&gt;Plug Door Patents&lt;/strong&gt; will yield many variants.  The ones you want are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.google.com/patents/US3051280&quot; rel=&quot;nofollow&quot;&gt;Outward-opening plug type door for aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.google.ca/patents/US5540404&quot; rel=&quot;nofollow&quot;&gt;Double-decked aircraft with plug door&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.google.com/patents/US4199120&quot; rel=&quot;nofollow&quot;&gt;Folding, plug type aircraft door&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I am going to build one of them as the entrance to my workshop - but I need to get the house built first.&lt;/p&gt;&#xA;" OwnerUserId="7048" LastEditorUserId="65" LastEditDate="2015-01-29T22:38:53.690" LastActivityDate="2015-01-29T22:38:53.690" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12173" PostTypeId="1" AcceptedAnswerId="12176" CreationDate="2015-01-29T21:18:55.300" Score="23" ViewCount="45259" Body="&lt;p&gt;How can pilots identify threats ahead of them if they don't have front lights like cars?&lt;/p&gt;&#xA;" OwnerUserId="7049" LastEditorUserId="849" LastEditDate="2015-02-01T18:32:40.593" LastActivityDate="2016-08-11T16:31:13.523" Title="How do pilots see at night if airplanes don't have front lights?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;visibility&gt;" AnswerCount="8" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12174" PostTypeId="2" ParentId="12173" CreationDate="2015-01-29T21:24:58.003" Score="29" Body="&lt;p&gt;Pretty much anything you want to avoid in the air is (or should be) lit. Other airplanes, radio towers, that sort of thing. If it's not lit, then either you couldn't have done much to avoid it anyway (bird), or you should be able to anticipate it (terrain).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes do have landing lights, which are quite bright and point forward. In the US, commercial flights are required to have them on under 10,000 feet. They are used to illuminate the runway for takeoff and landing. Planes should not be close enough to illuminate anything with their landing lights until landing though, and they are required to be on to allow aircraft to see each other more easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxi lights are similar but generally less bright, and help the pilots see where they are going when taxiing on the ground without airport lighting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This diagram of lights on the MD-11 shows the main areas illuminated by the taxi and landing lights. The other lights help to make the aircraft more visible as well. Runway turnoff lights on airliners also help to light up areas to the side of the aircraft after landing to more easily see upcoming runway turnoffs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rhLB6.jpg&quot; alt=&quot;Lights on MD-11&quot;&gt;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.aerospaceweb.org/question/electronics/q0263.shtml&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-29T22:03:20.970" LastActivityDate="2015-01-29T22:03:20.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12175" PostTypeId="2" ParentId="12173" CreationDate="2015-01-29T21:25:18.860" Score="7" Body="&lt;p&gt;They don't really need to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hills and other man-made static obstacles are mapped and lit and height limitations are published to which the pilot can follow to stay safe as long as he knows were he is. Landing strips will be lit up for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other planes will be lit up with navigation lights (red and green) and a pulsing beacon to draw the eye. Also during the night pilots will be flying IFR, which means the Air traffic control will be keeping planes away from each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And they hope no birds will be flying in their path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A light on the plane won't be enough to light for obstacle any way and provide a nuisance on the ground for the people trying to sleep.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-29T21:25:18.860" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12176" PostTypeId="2" ParentId="12173" CreationDate="2015-01-29T21:28:06.083" Score="47" Body="&lt;p&gt;Short answer: they do have front lights!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zr9aC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: There's lots of stuff for a ground vehicle (such as a car) to hit, because there's lots of stuff close to the ground.  There's not much in the air for an aircraft to hit, besides other aircraft.  Lights on an aircraft in flight are to help the airplane &lt;em&gt;be seen&lt;/em&gt;, not to help the airplane see.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On landing, forward-pointed lights are nice to have, but since runways are illuminated, it's possible to land safely without them.  Airliners in particular will probably never be landing on a darkened runway and need to worry about hitting invisible terrain or obstacles ahead, because they're always either above the obstacles or they're on a known safe descent path.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-01-29T21:28:06.083" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12177" PostTypeId="2" ParentId="12133" CreationDate="2015-01-29T23:47:17.140" Score="0" Body="&lt;p&gt;If the blackbox is intact, procedures described in other answers would apply. If, however, the data storage device (ssd, tape, etc.) itself is damaged, it will be given to forensic experts such as police criminal unit or other expert group or company that specializes in data recovery. For them it doesn't make much difference that the storage device is in fact an aircraft flight data recorder storage, they handle it in pretty much the same manner as any other device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blackbox itself is unimportant, only the data on storage devices is.&lt;/p&gt;&#xA;" OwnerUserId="7033" LastActivityDate="2015-01-29T23:47:17.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12178" PostTypeId="1" CreationDate="2015-01-30T00:01:23.687" Score="2" ViewCount="425" Body="&lt;p&gt;As a Canadian teenager hoping to become a commercial pilot, I'd like to know how hard it actually is to live the life of a pilot. I've heard from some people that the hours can be pretty gruesome, which is obviously a little off-putting. Are you able to maintain a relationship?Are the hours off-duty at home plentiful enough or few and far between? Is the pay worth it? Do you get vacation days and/or sick days like any other job? Any details on the life of a pilot and whether or not you'd suggest it would be much appreciated.&lt;/p&gt;&#xA;" OwnerUserId="7051" LastEditorUserId="7051" LastEditDate="2015-01-30T01:13:28.003" LastActivityDate="2015-01-30T01:13:28.003" Title="Is being a pilot stressful or hard?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;&lt;canada&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-01-30T06:14:33.817" ContentLicense="CC BY-SA 3.0" />
  <row Id="12179" PostTypeId="1" CreationDate="2015-01-30T00:36:20.790" Score="3" ViewCount="693" Body="&lt;p&gt;Assuming you are aerobatically trained, IFR rated, have an aircraft that is rated for the aerobatic maneuvers you are planning to perform (let us assume that it is acrobatic category, even), and the aircraft in question is type certified and equipped for flight under IFR, how would you plan out and safely execute a set of aerobatic maneuvers in IMC (think solid cloud, but without serious up/downdrafts, icing, or lightning hazards) while flying under IFR?  Can you define a &quot;box clearance&quot; in an IFR flight plan, akin to a VFR aerobatic box, only defined by coordinates or intersections instead of ground reference points?  How feasible is it to carry out the Aresti catalog maneuvers by reference to flight instruments alone?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-01-30T03:16:33.717" Title="Aerobatics in &quot;firm&quot; IMC -- how would one do it?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;&lt;aerobatics&gt;" AnswerCount="1" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12180" PostTypeId="1" CreationDate="2015-01-30T00:39:30.630" Score="4" ViewCount="1757" Body="&lt;p&gt;Are there any acrobatic-category aircraft that are also type-certificated/rated and equipped for flight under the instrument flight rules?  What limitations would be placed on such an airplane when flying as an IFR aircraft vs. a VFR aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="5517" LastEditDate="2015-02-19T19:34:35.577" LastActivityDate="2015-02-19T19:34:35.577" Title="Are there any IFR-certificated and equipped aerobatic aircraft?" Tags="&lt;aircraft-design&gt;&lt;instrument-flight-rules&gt;&lt;aircraft-certification&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12182" PostTypeId="1" AcceptedAnswerId="12230" CreationDate="2015-01-30T00:57:07.300" Score="6" ViewCount="1272" Body="&lt;p&gt;I enjoy watching RC helicopter stunts like &lt;a href=&quot;https://www.youtube.com/watch?v=Qrmd_Qdryos&quot; rel=&quot;nofollow&quot;&gt;these&lt;/a&gt;.  Many RC pilots are very talented, executing barrel rolls and other inversions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How come we don't see these kind of displays at airshows?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="1696" LastEditDate="2015-02-05T16:34:23.683" LastActivityDate="2015-02-07T12:57:35.963" Title="Why aren't there more helicopter aerobatics at airshows?" Tags="&lt;helicopter&gt;&lt;aerobatics&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12183" PostTypeId="2" ParentId="12182" CreationDate="2015-01-30T01:16:47.987" Score="11" Body="&lt;p&gt;There just aren't many helicopter aerobatic pilots around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one I know of: &lt;a href=&quot;https://www.youtube.com/watch?v=mQT26oxOG4c&quot;&gt;Chuck Aaron&lt;/a&gt; he can do the typical maneuvers in a specially modified helicopter.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-30T01:16:47.987" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12184" PostTypeId="1" AcceptedAnswerId="12194" CreationDate="2015-01-30T01:38:50.263" Score="40" ViewCount="96908" Body="&lt;p&gt;I find it funny that at gas stations, generally you can purchase &quot;regular&quot; gasoline (in various octane levels) or diesel. At airports, generally you can purchase 100LL avgas or Jet-A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you compare diesel to Jet-A, and &quot;regular&quot; gasoline to avgas? If so, what are the differences? Why are there only two classes of fuel - are there others that I don't know about?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2018-06-30T08:46:41.347" Title="What are the differences between fuel types (comparing with vehicles)?" Tags="&lt;jet-engine&gt;&lt;piston-engine&gt;&lt;fuel&gt;&lt;engine&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="12185" PostTypeId="2" ParentId="12179" CreationDate="2015-01-30T03:16:33.717" Score="7" Body="&lt;p&gt;No - you don't do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First and obvious reason, there's no body to see it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps much more important is safety though. When pulling a loop, it's not like flight simulator where you just yank the stick aft and watch the attitude indicator (AI). An aerobatic pilot is constantly checking his attitude by looking at his wing tips, quickly glancing the left and right sides back and forth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, the AI is usually caged (meaning it is locked to prevent rotation) in such violent maneuver. The proper procedure is cage the AI, perform the maneuver, check straight and level (&lt;em&gt;visually&lt;/em&gt;), then uncage the AI. If you don't, the gyroscope will tumble quite some time before it settles again, rendering it useless. Meaning, if you perform in IMC, you won't have accurate AI information for recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For nearly vertical maneuvers (e.g. stall turn, rolling while vertical), even a functioning AI wouldn't help, since horizontal direction is undefined in this state. The AI and compass will just flip, yet you have no way to determine which way you go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Violent G-forces also mean it is much more difficult to read instruments during such maneuver.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-30T03:16:33.717" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="12186" PostTypeId="2" ParentId="12184" CreationDate="2015-01-30T03:18:42.503" Score="6" Body="&lt;p&gt;JetA is indeed a kind of diesel fuel prepared for use in turbines. There are a number of other jet fuels, such as JP1, JP2, etc, but these are fairly rare, since they are usually used for military turbines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;100LL is fuel for piston engines and is formulated much like car gas, with some chemical differences and a higher octane (100).  Some engines  can use 87 &quot;mogas&quot; buy they are mostly small engines and some converted ones. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-01-30T03:18:42.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12187" PostTypeId="2" ParentId="12184" CreationDate="2015-01-30T03:20:42.657" Score="7" Body="&lt;p&gt;In general, 100LL avgas compares to Regular Unleaded and Jet-A compares to Diesel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other types available - 80/87 Avgas (tinted red) used to be the equivalent of Regular Leaded and 100/130 (tinted green) was Premium. These fuels are rather difficult to find now, and in some areas simply unavailable. 115/145 Avgas is like Formula-1 racing fuel. A refinery might make a few truckloads on special order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet-A is basically clean Diesel, you can put it in your tractor or big truck with no harm to anything other than your wallet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet-B is regular jet fuel mixed with gasoline. Starts better in very cold weather, but also burns really, really well if you crash.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-01-30T03:20:42.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12188" PostTypeId="2" ParentId="12184" CreationDate="2015-01-30T03:46:42.523" Score="22" Body="&lt;p&gt;There have been several fuels used historically through aviation.  I'll start with the common fuels here, and then cover fuels that are purely of historical interest.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Common fuels&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;100LL -- The garden-variety &quot;avgas&quot; used by most piston-engine aircraft.  Similar to a superpremium gasoline in formulation (lots of high-octane alkylate!) with a small amount of tetra-ethyl lead (TEL) added to it (the LL stands for &quot;low lead&quot;).  Despite its formulation, it plays an analogous role in the aviation (esp. GA) world to the gasoline we put in our cars.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;87UL/E0 (similar fuels are called 82UL or 85UL) -- This is a tightly specified form of motor gasoline (mogas) -- &lt;strong&gt;without&lt;/strong&gt; any ethanol or oxygenates in it, as many aircraft fuel systems aren't compatible with ethanol -- that is used in low-compression aviation piston engines mounted in airframes certified or STCed for operation on motor gasoline.  Many light (SLSA) and ultralight aircraft, as well as some certificated types, can use this as it can be cheaper than 100LL; however, it's rarer to find it on the ramp, while 100LL is ubiquitous in the US and in other places where spark-ignition GA engines are common.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet-A/JP-5/JP-8 -- Jet fuel, or turbine fuel in some contexts.  It is a highly refined kerosene that can be burned both in turbine engines and in diesel piston engines; spark-ignition engines can't use it though.  Additive packages (Prist&amp;trade; or generic fuel system icing inhibitor (FSII), static dissipative additives, biocides, and other additives) are commonly found in this fuel.  It can be found &lt;strong&gt;anywhere&lt;/strong&gt; commercial aviation is present, and thus is available worldwide.  Role-wise, it is analogous to commercial diesel fuel, but furthermore can be &lt;em&gt;substituted&lt;/em&gt; for diesel in some situations (the military runs diesel engines on JP-8 all the time, but many jet fuels require a lubricity additive to be used successfully in diesel engines not purpose-designed to run on jet fuel).  JP-8 and JP-5 are the military kerosene-based jet-fuels (JP-5 was the original naval jet fuel, with JP-8 being a modern derivative suitable for tri-service use).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Somewhat unusual fuels&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet-B/JP-4 -- This fuel is what is known as a &quot;wide-cut&quot; jet fuel, with properties akin to a mixture of gasoline and kerosene (it contains hydrocarbons from both fractions).  It was used in early jet aviation as it is easier to refine and ignite than Jet-A, but it has poorer safety properties than Jet-A.  It can be found in extreme northern climes where Jet-A begins to crystallize or gelatinize.  JP-4 is an older military jet fuel type similar in character to Jet-B, but it was replaced by JP-8.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Propane/Liquefied Petroleum Gas (LPG) -- This is the same stuff you buy tanks of for your gas grill.  It is the fuel of choice for hot-air balloons, as it burns cleanly and lights off reliably with only a low-power ignition system fitted (such as a piezo sparker).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Historical or otherwise rare fuels&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;80/87 -- A low-octane leaded gasoline, akin to the leaded motor gasoline of bygone days.  Aircraft don't need this any longer -- you can always put 100LL into a plane that would otherwise use 80/87, and most low-compression engines nowadays burn 87UL instead.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;100/130 -- The predecessor to 100LL, with twice the lead content -- this was a common fuel for high-compression piston engines in the past; all such engines burn 100LL now though.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;115/145 -- This super-specialty leaded fuel is used for piston-engine air racing and other applications where maximum performance is needed from forced-draft, very-high-compression piston engines such as those found in WWII era fighter aircraft.  As others have said, it's only seen in the occasional truckload headed to Reno.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;JP-7 -- A super-high-flashpoint jet fuel formulated for the SR-71 Blackbird, but no longer made due to the discontinuance of the Blackbird program.  It &lt;em&gt;cannot&lt;/em&gt; be used in ordinary jet engines (it won't ignite reliably).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;RP-1 -- An ultra-refined kerosene, used for rocketry.  Can be substituted for jet fuel, if you don't mind it costing more than ancient French wine on gallonage basis!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Future fuels&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;94UL, G100UL, 100SF, 91/96UL -- There is an ongoing effort in the US to develop an unleaded fuel with sufficient octane rating to be used in high-compression piston engines; several refiners and tinkerers have been working on high-performance blended fuels based on alkylate base stocks with proprietary additive packages to meet this need.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-03-11T11:46:03.203" LastActivityDate="2015-03-11T11:46:03.203" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="12189" PostTypeId="1" AcceptedAnswerId="12198" CreationDate="2015-01-30T04:00:57.187" Score="4" ViewCount="1596" Body="&lt;p&gt;For example, consider you are flying the 8KCAB Super Decathlon (a fairly common acrobatic plane) that had G1000 (using the flagship Garmin glass cockpit as an example, answers for other types of GA glass are welcome) avionics fitted to it, and you were about to go off and practice your favorite aerobatic routine in the local aerobatics box.  Would you have to do anything equivalent to &quot;caging&quot; in order to keep the attitude indication functions of the G1000 from misbehaving during aerobatic maneuvers, or is that not an issue with the types of &quot;glass cockpit&quot; instrumentation used in the GA world?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="1696" LastEditDate="2015-02-05T15:38:27.727" LastActivityDate="2015-02-05T15:38:27.727" Title="How do GA glass cockpit attitude indicators handle aerobatics?" Tags="&lt;aerobatics&gt;&lt;glass-cockpit&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12190" PostTypeId="5" CreationDate="2015-01-30T04:01:46.633" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-01-30T04:01:46.633" LastActivityDate="2015-01-30T04:01:46.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12191" PostTypeId="4" CreationDate="2015-01-30T04:01:46.633" Score="0" Body="A pilot who is under training and does not yet have full pilot privileges." OwnerUserId="3386" LastEditorUserId="1696" LastEditDate="2015-04-17T02:17:33.097" LastActivityDate="2015-04-17T02:17:33.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12192" PostTypeId="5" CreationDate="2015-01-30T04:06:56.523" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-01-30T04:06:56.523" LastActivityDate="2015-01-30T04:06:56.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12193" PostTypeId="4" CreationDate="2015-01-30T04:06:56.523" Score="0" Body="A technology which moves control surfaces by processing pilot input via software." OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-01-30T06:14:45.640" LastActivityDate="2015-01-30T06:14:45.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12194" PostTypeId="2" ParentId="12184" CreationDate="2015-01-30T04:07:34.943" Score="76" Body="&lt;p&gt;Broadly speaking, there are three families of motor fuel that you're probably interested in: &lt;strong&gt;Diesels&lt;/strong&gt;, &lt;strong&gt;Kerosenes&lt;/strong&gt;, and &lt;strong&gt;Gasolines&lt;/strong&gt;.&lt;br&gt;&#xA;The difference between the families mainly has to do with the molecular weight (and thus boiling point / vapor pressure) of the fuel components - in order above from heaviest to lightest. The differences within each family are related to refining, blending, and additives, as well as process controls imposed on the fuel.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;The Diesel Family&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the diesel family we have things like Highway Diesel and the various grades of home heating oil.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For transportation purposes these fuels are used in compression-ignition engines (&quot;diesel engines&quot;), where a high temperature and pressure will cause the fuel to ignite and burn, producing power.&lt;br&gt;&#xA;For other purposes (like heating) we basically light the stuff on fire and are happy it burns.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Kerosene Family&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Kerosene family are close cousins of the Diesels, including K-1 and K-2 Kerosene (obviously) and Jet-A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet-A is a high-purity kerosene based fuel manufactured under a specific ASTM standard (D1655), with specific physical properties, and is used in jet turbine engines.  Fuel not meeting the Jet-A specification is generally recycled in the production chain for other purposes (for example it may be used in blending kerosene for heating, or blended into highway diesel).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet-A is suited for turbine engines, but can also be burned in other compression-ignition piston engines like diesel can (there are a wide variety of &lt;a href=&quot;http://www.deltahawkengines.com&quot;&gt;aerodiesel engines&lt;/a&gt; available from several manufacturers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other grades of Kerosene are used for motor fuels, cooking fuel (&quot;camp stove fuel&quot; is typically kerosene) heating, lighting, etc. depending on their refining and purity.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Gasoline Family&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the gasoline family we have Avgas, Autogas, and &quot;Gasohol&quot;, all designed for use in spark-ignition engines.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Aviation Gasoline (Avgas)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Avgas actually comes in several grades, all manufactured to an ASTM standard (D910), with specific physical properties and specific permitted and required additives (such as Tetra-Ethyl Lead - TEL).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The grade (octane rating) of aviation gasoline is identified by colored dyes added to the blend.&lt;br&gt;&#xA;The colors used in the US are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Green: AvGas 100 (100/130 Octane)&lt;/li&gt;&#xA;&lt;li&gt;Blue: AvGas 100LL (100/130 Octane)&lt;br&gt;&#xA;(This was formulated as a replacement for AvGas 100, with half the lead - hence 100&lt;b&gt;LL&lt;/b&gt; - Low Lead)&lt;/li&gt;&#xA;&lt;li&gt;Red: AvGas 80 (80/87 Octane)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Generally 100LL is the most widely available aviation fuel because it works in the widest range of engines. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Autogas (automotive gasoline)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Automotive gasoline comes in multiple octane grades, but generally it's all varying blends of &quot;regular&quot; (87 octane) and &quot;premium&quot; (93 octane or higher).&lt;br&gt;&#xA;Automotive gasoline is manufactured under a different ASTM standard from Aviation gasoline (there are several applicable standards, D4814 is commonly used), which permits different additives including ethanol (usually up to 10%).  &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;&quot;Gasohol&quot;&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Gasohol is a slang term for automotive gasoline with &lt;em&gt;any&lt;/em&gt; amount of ethanol blended into it, but these days it's often used to refer to blends like E85 (85% Ethanol, 15% gasoline stock).&lt;br&gt;&#xA;Flex-fuel car engines and a few other specialty engines are designed to burn this fuel.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;So what's the difference?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Why don't we burn highway diesel or heating kerosene in a 747?&lt;br&gt;&#xA;In a word, purity. The additional controls imposed on Jet-A fuel by the associated standard produce a product with well-known properties. When you fuel a plane with Jet-A you can be confident that fuel won't freeze in the tanks at altitude (at least not unless you cold-soak it below -40 degrees). You also know the fuel will be &quot;clean&quot; and won't gunk up fuel filters or leave deposits inside the combustion core of the engine that can cause problems later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand we don't burn Jet-A in a Mack Truck because it would be prohibitively expensive: Highway diesel doesn't have to meet the same strict tolerances as jet fuel, and theres no reason to burn a more tightly specified (and thus more expensive) fuel when a less expensive one is readily available.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The difference between Aviation Gasoline and Automotive Gasoline is a bit more subtle: the core blend stocks are extremely similar, but the additive packages are very different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest concern for aviation users is usually the ethanol commonly blended into automotive gasoline: Rubber components in aircraft fuel systems were not designed to handle alcohols, and can be damaged/degraded by ethanol.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For cars the concern is the lead found in aviation gasoline. Any &quot;modern&quot; car (with a catalytic converter and oxygen sensors in the exhaust system) can't burn leaded fuel as the lead byproducts in the exhaust will foul both the catalyst matrix and the oxygen sensors (though a &lt;a href=&quot;http://en.wikipedia.org/wiki/Plymouth_Belvedere&quot;&gt;1950s Plymouth Belvedere&lt;/a&gt; would have no trouble burning the stuff).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/initiatives/avgas/&quot;&gt;Work on an unleaded aviation fuel is ongoing&lt;/a&gt; - theoretically the fuel that comes out of that process could be equally suitable as a road fuel and an aviation fuel, however the chances of it making its way to your corner gas station are relatively slim, except possibly as a blend stock from batches that don't meet the final specification for a 100-octane unleaded aviation fuel, but are suitable for recycling into automotive gasoline blends.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-01-31T03:22:03.167" LastActivityDate="2015-01-31T03:22:03.167" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="12195" PostTypeId="5" CreationDate="2015-01-30T04:09:29.593" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-01-30T04:09:29.593" LastActivityDate="2015-01-30T04:09:29.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12196" PostTypeId="4" CreationDate="2015-01-30T04:09:29.593" Score="0" Body="Auxiliary Power Unit. A device for providing alternate power to an aircraft, usually located in the aircraft's tail." OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-01-30T08:20:37.047" LastActivityDate="2015-01-30T08:20:37.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12197" PostTypeId="2" ParentId="1636" CreationDate="2015-01-30T04:59:10.817" Score="16" Body="&lt;p&gt;I've flown VFR-on-top plenty of times.  Navigation is simple: even the most basic airplane is required to have at the very least a compass, a clock and an airspeed indicator, which can be used to navigate much more accurately than you'd expect, given a reasonably good &quot;winds aloft&quot; weather report.  Most airplanes also have some kind of radio navigation equipment as well.  Furthermore, just because you are flying on top of a cloud layer, that doesn't necessarily mean you have no visual references for navigation.  For example, mountains may poke through the cloud ceilings, or there may be an area of fog covering a portion of your route, with clear skies at your departure point and your destination.  On one flight, I flew &quot;VFR-on-top&quot;, but could see through the clouds to the streetlights below (it was dusk) even though my home airport was reporting IFR conditions (1/2 mile visibility, ceilings at ground level -- but it was a very thin layer of clouds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether or not it can be done safely depends upon the circumstances.  Getting lost typically isn't the issue, but rather whether you'll be able to descend in VFR conditions to land at your destination.  Check the weather at your destination, paying attention to temperature and dewpoint spreads, and make sure you've got other options within the range of your aircraft.  Also keep in mind that while you're on top, if you have an engine failure, you'll be making an engine-out IFR descent into unknown terrain below, unless you are within gliding distance of a suitable landing spot in clear weather nearby!&lt;/p&gt;&#xA;" OwnerUserId="4159" LastActivityDate="2015-01-30T04:59:10.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12198" PostTypeId="2" ParentId="12189" CreationDate="2015-01-30T06:36:00.350" Score="5" Body="&lt;p&gt;I fly a Super Decathlon with an Aspen E1000.  While an excellent PFD, I certainly would not trust it in aerobatic flight.  There's no cage function, and no way that I'm aware of to keep the attitude indicator from misbehaving, which I've seen it do firsthand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also fly the Avidyne R9 system, which also does not have a caging function.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, I downloaded the Garmin G1000 manual, which says nothing about a way to cage the GRS 77.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This lack of commonly available GA glass-cockpit aerobatic-capable instrumentation  probably contributes to why &lt;a href=&quot;https://aviation.stackexchange.com/a/12185/167&quot;&gt;one does not do aerobatics in IMC.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-01-30T06:36:00.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12199" PostTypeId="1" CreationDate="2015-01-30T07:21:12.500" Score="6" ViewCount="2467" Body="&lt;p&gt;Do the windows in a 172 provide any protection from the sun or is too bright? Particularly, if one wants to do a flying lesson and was told to bring sunglasses more than once.  So, is it critical?  My friend doesn't have sunglasses and would have to get prescribed ones which he can't get now. He got a gift of a flying lesson so he wants to try it but is being in the plane without sunglasses doable?  Or will he be squinting the entire time? Or is it really bad for your eyes?&lt;/p&gt;&#xA;" OwnerUserId="870" LastActivityDate="2015-03-18T00:30:17.513" Title="Is flying without sunglasses in daylight doable in a Cessna 172?" Tags="&lt;medical&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12200" PostTypeId="1" AcceptedAnswerId="12207" CreationDate="2015-01-30T07:22:57.393" Score="13" ViewCount="2224" Body="&lt;p&gt;Can modern airliners still be seen as stressed-skin aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. is the skin, whether it be aluminium or composites, still an integral structural member of the airplane?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2015-01-30T11:12:57.487" Title="Are modern airliners still stressed-skin aircraft?" Tags="&lt;airliner&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12201" PostTypeId="2" ParentId="12199" CreationDate="2015-01-30T08:00:01.010" Score="12" Body="&lt;p&gt;Definitely doable. No real protection from the sun just through the windshield but I flew a C172 for many years only using sunglasses occasionally. Just don't make the same mistake I did when I first started flying- paid a lot for a pair of polarised sunglasses then jumped in the cockpit and all the LCD screens went blank! :)&lt;/p&gt;&#xA;" OwnerUserId="5701" LastEditorUserId="5701" LastEditDate="2015-01-30T10:23:02.310" LastActivityDate="2015-01-30T10:23:02.310" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12202" PostTypeId="1" CreationDate="2015-01-30T08:14:55.080" Score="1" ViewCount="114" Body="&lt;p&gt;Regarding the events of MH370, if an modern aircraft (like the Dreamliner, or the A350) turn off deliberately all it's radio-communication under control and fly under the radar scope, is it really possible that with so many nowaday technology, there is still no way to know the whereabouts of an aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are new fallback location beacons set?&lt;/p&gt;&#xA;" OwnerUserId="7061" LastEditorUserId="7532" LastEditDate="2019-02-08T15:12:48.817" LastActivityDate="2019-02-08T15:12:48.817" Title="Can modern aircraft also &quot;disappear&quot;?" Tags="&lt;radio-communications&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="1" ClosedDate="2015-01-30T09:27:56.320" ContentLicense="CC BY-SA 4.0" />
  <row Id="12203" PostTypeId="2" ParentId="12199" CreationDate="2015-01-30T09:40:35.723" Score="3" Body="&lt;p&gt;Nobody &lt;strong&gt;needs&lt;/strong&gt; sunglasses, they are a just a convenience. They are very helpful for sure, especially in bright sunlight and hazy conditions, but not absolutely essential. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for what to get you want &lt;strong&gt;non-polarized&lt;/strong&gt;, and if you have require an eyeglass prescription on your medical the sunglasses will need to be that prescription. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-01-30T09:40:35.723" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12204" PostTypeId="2" ParentId="12189" CreationDate="2015-01-30T09:51:25.617" Score="2" Body="&lt;p&gt;Whether caging is required depends on the system. Some glass cockpits use conventional gyros which can tumble and mis-align, while others use accelerometers, solid state gyros, or laser ring gyros which have no mechanical parts and do not require caging. I believe the G1000 uses solid state gyros. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That does not means that you won't get erroneous readings from a non-mechanical glass cockpit during aerobatics, processing power and software design are other factors that come into play. It does mean that you should not have alignment issues once you are done. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-01-30T09:51:25.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12205" PostTypeId="1" AcceptedAnswerId="12223" CreationDate="2015-01-30T09:53:41.150" Score="35" ViewCount="9842" Body="&lt;p&gt;I originally asked the same question on &lt;a href=&quot;https://space.stackexchange.com/questions/7967/how-do-astronauts-overcome-the-boredom-from-the-daily-routine&quot;&gt;Space Exploration&lt;/a&gt; but will repeat it also here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before every takeoff and every landing, there are several routine checks which need to be done in order to provide the highest maximum safety to passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But after certain number of repetitions, these tasks can feel as &lt;em&gt;tedious&lt;/em&gt; especially if you are flying a plane which goes in &quot;turns&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Real example of what I mean is commercial line between Prague (PRG) and Frankfurt (FRA) where plane lands, people go out, new people go in and plane goes back. And so on)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do pilots and other personnel make sure that they actually do go through the check every single time without &quot;It was OK last time, so it will be ok this time. Skip it and say it is ok&quot; ?&lt;/p&gt;&#xA;" OwnerUserId="7066" LastEditorUserId="100" LastEditDate="2020-04-28T08:08:46.810" LastActivityDate="2020-04-28T08:08:46.810" Title="How do pilots stay disciplined and use checklists, even after they have become routine?" Tags="&lt;safety&gt;&lt;checklist&gt;" AnswerCount="7" CommentCount="15" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12206" PostTypeId="2" ParentId="12149" CreationDate="2015-01-30T10:03:27.553" Score="4" Body="&lt;p&gt;There are many planes fitted with air brakes. StuKas, for example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To prevent the airplane from building up too much speed, dive brakes (large perforated flaps) are needed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Similarly, flaps are/were used to &quot;brake&quot; when landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;But&lt;/strong&gt;: They won't be used to slow down because of &quot;flying cows&quot; &quot;grazing&quot; on the &quot;air street&quot;, like cars would. Either a plane can turn to evade the birds, or it will have to go right through them. But then, if you can believe one Cpt. Sullenberger, you won't even see a bird strike coming like that...&lt;/p&gt;&#xA;" OwnerUserId="1745" LastActivityDate="2015-01-30T10:03:27.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12207" PostTypeId="2" ParentId="12200" CreationDate="2015-01-30T10:05:44.400" Score="11" Body="&lt;p&gt;Yes, absolutely. The skin transfers shear stresses between the &lt;a href=&quot;http://en.wikipedia.org/wiki/Longeron&quot; rel=&quot;nofollow noreferrer&quot;&gt;stringers or longerons&lt;/a&gt; which run lengthwise along the fuselage and transmit tensile or compressive stress. Cutouts and openings (for doors and windows) need special local reinforcements, so the reduced structure can still withstand the loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equally, the wing skin is the main element for the transmission of torsional loads. In today's airliners, the spar is part of the skin, but the wing skin ahead and aft of it is also a part of the primary structure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, stress follows stiffness. When a structure is loaded, it will deform, and those parts which withstand deformation most will carry most of the load. In the end, all parts which have similar stiffness will carry loads in proportion to their cross section. Since most of an airliner's structure is made from aluminum, it has the same stiffness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/9917/why-does-the-757-fuselage-bend-more-on-turbulence-than-those-of-other-airplanes&quot;&gt;this question&lt;/a&gt; for one example clearly showing fuselage skin deformation.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-01-30T11:12:57.487" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12208" PostTypeId="1" AcceptedAnswerId="12217" CreationDate="2015-01-30T10:27:54.597" Score="34" ViewCount="26654" Body="&lt;p&gt;I heard that sometime an aircraft fly inside a cloud, and I'm wondering how that works - how clearly can the pilot see while inside the cloud?&lt;br&gt;&#xA;What if a cloud is &quot;too large&quot;? (Is there a maximum size of cloud a pilot can fly through?)&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="64" LastEditDate="2015-01-30T16:06:10.907" LastActivityDate="2020-10-25T19:40:29.347" Title="How can pilots fly inside a cloud?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;&lt;flight-instruments&gt;&lt;attitude&gt;&lt;imc&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12209" PostTypeId="2" ParentId="12173" CreationDate="2015-01-30T10:32:12.370" Score="4" Body="&lt;p&gt;For civil aviation, planes are lit to make them visible, not so much to illuminate obstacles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aviation is (or was) another matter, in WWII operations were sometimes conducted at night with upwards of a thousand unlit planes. Moonlit nights were to be avoided where possible, because moonlight made it rather too easy for pilots to see other aircraft, and the full moon was called a &quot;fighter's moon&quot;. However, especially hazardous operations were sometimes scheduled for the full moon (e.g. see &quot;The Dam Busters&quot;, Paul Brickhill) despite the extra risk to the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe someone can ... illuminate us, as to whether this is still a consideration.&lt;/p&gt;&#xA;" OwnerUserId="4068" LastActivityDate="2015-01-30T10:32:12.370" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12210" PostTypeId="2" ParentId="12208" CreationDate="2015-01-30T10:37:12.957" Score="12" Body="&lt;p&gt;A pilot has no clearer vision through a cloud than you looking out the window at the same time. However, the flight can proceed in safety with a combination of instruments and the facilities available to an air traffic controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for a pilot to enter a cloud, s/he must be flying under Instrument Flight Rules, which among other things means that an air traffic controller is responsible for separation from other aircraft (contrast with Visual Flight Rules where the pilot him/herself is responsible for seeing and avoiding other aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, pilots have instruments, such as an artificial horizon, which allows them to maintain any climb/descent and turn required without sight of an actual horizon - the main way a pilot can usually tell if they are climbing, descending or turning.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-01-30T11:09:23.567" LastActivityDate="2015-01-30T11:09:23.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12211" PostTypeId="2" ParentId="12208" CreationDate="2015-01-30T10:37:21.160" Score="18" Body="&lt;p&gt;Pilots that fly in clouds knowingly will be under IFR (instrument flight rules) and will have contact with traffic control to keep away from other planes. If you end up in a cloud by accident the standard procedure is to turn around 180° keeping the same height and continue until out of the cloud (or transfer to IFR).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot in a cloud doesn't rely on what he sees outside and instead looks at his &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_instruments&quot; rel=&quot;noreferrer&quot;&gt;instruments&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/M5DDk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;source &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Six_flight_instruments.JPG&quot; rel=&quot;noreferrer&quot;&gt;wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are in order: airspeed display, artificial horizon, altitude display, turn coordinator, heading (compass) and vertical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another layout for this information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9u54N.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the same-ish layout, airspeed on the left, horizon in the center, altitude on the right and heading at the bottom.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-01-30T11:59:46.643" LastActivityDate="2015-01-30T11:59:46.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12212" PostTypeId="1" AcceptedAnswerId="12215" CreationDate="2015-01-30T10:56:01.643" Score="24" ViewCount="21848" Body="&lt;p&gt;While in a flight, a pilot wants to sleep.  Given that the aircraft has an autopilot facility, are they allowed to sleep for a while (e.g., half an hour)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would happen if it's not allowed, but they still did it?  Would air traffic controllers know?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="956" LastEditDate="2015-01-30T21:52:30.863" LastActivityDate="2019-04-13T08:40:59.723" Title="Is a pilot allowed to sleep during a flight?" Tags="&lt;air-traffic-control&gt;&lt;autopilot&gt;&lt;pilots&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12213" PostTypeId="2" ParentId="3306" CreationDate="2015-01-30T10:57:13.403" Score="3" Body="&lt;p&gt;Does a pusher propeller run in disturbed airflow, producing more vibration and noise? Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does a pusher engine have more cooling issues? Yes if it is a piston engine (turboprops are cooled by their own internal airflow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However there is one thing in favor of the pusher configuration which needs a better evaluation: A pusher propeller picks up airflow that is already decelerated by the wing and fuselage to generate thrust, while a puller propeller picks up undisturbed air to blow it onto the fuselage and wings, which in turn decelerate the airflow. This difference probably means that a pusher engine may be somehow more efficient at higher speeds. A twin pusher, shown in the following photo, was developed here in my country in the 80's called CBA-123 (two prototypes were built) and the experience with that airplane points in this direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zUDju.jpg&quot; alt=&quot;CBA-123&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7070" LastEditorUserId="11671" LastEditDate="2018-07-29T18:35:11.430" LastActivityDate="2018-07-29T18:35:11.430" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="12214" PostTypeId="2" ParentId="12212" CreationDate="2015-01-30T11:01:49.107" Score="8" Body="&lt;p&gt;No the pilot is not allowed to sleep on the job. Not unless another qualified human relieves him of his duties as pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An emergency can happen at &lt;em&gt;any time&lt;/em&gt; in flight and the pilot must be ready to deal with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot sleeping would result in him not responding to air traffic control but that can have other causes like a failed radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airline pilots have strict work hours they need to keep to ensure they are well rested before starting a flight. If he feels he is too tired he is obligated to refuse flying and let a better rested pilot take over.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-01-30T11:01:49.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12215" PostTypeId="2" ParentId="12212" CreationDate="2015-01-30T11:01:50.327" Score="31" Body="&lt;p&gt;Airline flight crews generally consist of at least 2 pilots. One pilot is designated as pilot flying, the other is the pilot not flying, observing instruments and flight parameters. If required, pilots can use &lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Crew_In-Seat_Rest&quot; rel=&quot;noreferrer&quot;&gt;Flight Crew in-Seat Rest&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;b&gt;Flight Crew in-Seat Rest&lt;/b&gt;&lt;br&gt;&#xA;  This is the process whereby pilots may take short periods of sleep (naps), while temporarily relieved of operational duties in accordance with carefully prescribed ‘controlled rest’ procedures, when part of a two-man operating crew of an in-flight aeroplane. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is not communicated to ATC and only allowed with two pilots present on the flight-deck. It is prohibited to have both pilots participate in &lt;strong&gt;in-Seat Rest&lt;/strong&gt; at the same time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also these related questions:&lt;br&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1712/how-do-pilots-rest-on-long-haul-flights&quot;&gt;How do pilots rest on long-haul flights?&lt;/a&gt;&#xA;&lt;br&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9521/what-if-pilot-feels-too-tired-before-his-flight/&quot;&gt;What if pilot feels too tired before his flight?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-01-30T15:08:34.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12216" PostTypeId="2" ParentId="12205" CreationDate="2015-01-30T11:20:46.307" Score="13" Body="&lt;p&gt;I can't speak for commercial operations, but from a GA point of view, the pre-flight checks and their importance are drilled in to you from your very first lesson. Its is stressed that the Pilot in Command is 100% responsible for verifying that the aircraft is fit for flight before even climbing in to the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few tricks that are used to stop you falling in to that &quot;Yeah, everything will be fine&quot; mindset and just skipping the checks&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Not doing the checks from memory, but actually doing them in reference to a physical check list.&lt;/li&gt;&#xA;&lt;li&gt;A prescribed order of checks, starting at a point on the aircraft and moving around methodically&lt;/li&gt;&#xA;&lt;li&gt;The fear of missing something, such as engine oil levels, which gets very serious once airborne. &lt;/li&gt;&#xA;&lt;li&gt;Once carrying passengers, especially nervous ones, they tend to feel safer when they've seen you PHYSICALLY checking the aircraft before flying it. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-01-30T17:40:04.900" LastActivityDate="2015-01-30T17:40:04.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12217" PostTypeId="2" ParentId="12208" CreationDate="2015-01-30T12:24:13.937" Score="77" Body="&lt;p&gt;When aircraft fly inside clouds, they fly under &amp;quot;instrument rules&amp;quot;. It doesn't matter whether the visibility is reduced (at night) or totally blocked (in a thick cloud), this mode of flying simply assumes the crew has no external visual reference, they fly solely using indications given by on-board instruments.&lt;/p&gt;&#xA;&lt;p&gt;The following short video shows a situation frequently encountered, the crew doesn't see anything outside prior to being so close to the ground, they are nearly landed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=XHJx7iJQnfY&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MdlGm.jpg&quot; alt=&quot;Landing without visibility&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Landing without visibility, source: &lt;a href=&quot;https://www.youtube.com/watch?v=XHJx7iJQnfY&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;After the problem of replacing external references has been solved, the next most important issue is to safely stay away from other aircraft. To prevent collisions, pilots are supported by air traffic control (ATC) from the ground. ATC determines aircraft location and altitude by relying on an on-board transponder. ATC issues appropriate information and instructions for pilots in order to maintain aircraft separated.&lt;/p&gt;&#xA;&lt;p&gt;Should ATC fail to separate aircraft, commercial aircraft are equipped with a safety net: In last resort, close aircraft, transponder-equipped, are detected and avoided by an on-board collision avoidance system. While this system is efficient when there are only 2 or 3 aircraft involved, the escape maneuver must be done quickly and can be therefore sharp enough for a passenger not belted to be injured. This doesn't work if the other aircraft isn't equipped of a transponder, but all commercial aircraft carry such equipment by regulation.&lt;/p&gt;&#xA;&lt;p&gt;All large airliners we know fly under instrument rules, regardless of the weather, or the time of day. However for a few runways, landing can be done  by a &lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/1430.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;circling maneuver&lt;/a&gt; (or circle-to-land maneuver) in which the crew approaches the runway using an instrumental guidance which is interrupted before landing (usually because the guidance is designed for another runway), leaving the crew under visual rules until touchdown (such maneuvers are known to be &lt;a href=&quot;https://www.skybrary.aero/index.php/A310,_vicinity_Moroni_Comoros,_2009&quot; rel=&quot;nofollow noreferrer&quot;&gt;more hazardous&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;For the sake of completeness, a special kind of visual flight, &lt;a href=&quot;https://aviation.stackexchange.com/q/31182/3201&quot;&gt;VFR Over The Top&lt;/a&gt;, may be allowed over the cloud layer, during the upper part of the flight, where the horizon and other aircraft can be seen.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;1. Technical aspects of instrument flying&lt;/h3&gt;&#xA;&lt;p&gt;It's technically possible to fly inside clouds, fog, snow, at night, etc, but this type of flight is regulated, it requires technical elements both in the aircraft and on the ground, and mandatory additional training for the pilot.&lt;/p&gt;&#xA;&lt;p&gt;Good sense, and regulation, require the pilot to be able, at any time, to:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a/ Maintain an aircraft safe attitude (flight conditions preservation),&lt;/li&gt;&#xA;&lt;li&gt;b/ Avoid obstacles and other aircraft (collision prevention),&lt;/li&gt;&#xA;&lt;li&gt;c/ Find their way to a landing aerodrome (navigation).&lt;/li&gt;&#xA;&lt;li&gt;d/ Know where they are (position awareness),&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Flying without visibility basically means knowing how to carry out these tasks without looking outside the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A: Maintain a safe attitude&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;One of the main references a pilot needs is the horizon. When the horizon is invisible, An artificial horizon reproduces the horizontal plane using a gyroscope. This instrument indicates whether the aircraft is pitched or rolled.&lt;/p&gt;&#xA;&lt;p&gt;Regarding altitude and speed, the same instruments are used both for visual and instrument flying: Barometric altimeter and airspeed indicator.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bp1Cc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bp1Cc.jpg&quot; alt=&quot;Standard aircraft instruments&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Main instruments, traditional presentation. Source: &lt;a href=&quot;http://www.aircraft-spruce.com/catalog/pspages/trintec9085.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Spruce&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image above (left-to-right, top-to-bottom):&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airspeed_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;speed&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Attitude_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;attitude&lt;/a&gt; (artificial horizon), &lt;a href=&quot;http://en.wikipedia.org/wiki/Altimeter&quot; rel=&quot;nofollow noreferrer&quot;&gt;altitude&lt;/a&gt;,&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Turn_and_slip_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;turn indicator&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Heading_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;heading&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Variometer&quot; rel=&quot;nofollow noreferrer&quot;&gt;vertical speed&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AO2B0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AO2B0.png&quot; alt=&quot;Standard aircraft instruments, electronic display&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Same instruments on the electronic primary flight display of a A330. &lt;a href=&quot;https://www.youtube.com/watch?v=Ag473iWhmYc&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Being aware of the aircraft attitude without external visual clues is not natural and more difficult than usually expected. There was a famous study (&lt;em&gt;&lt;a href=&quot;https://ia800309.us.archive.org/15/items/180degreeturnexp11brya/180degreeturnexp11brya.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;180-degree turn experiment&lt;/a&gt;&lt;/em&gt;, Bryan, Stonecipher, Aron) in 1954 which showed a pilot not trained to fly with instruments loses control of the aircraft in 3 minutes in average if external references are lost.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;B: Collision prevention&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;As mentioned, a collision prevention service is provided by radio from the ground. An aircraft flying without visibility is separated by &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;air controllers&lt;/a&gt; (ATC) from all other aircraft. The exact type of separation provided varies with airspace category, in particular when radar coverage is missing, e.g. when flying over oceans. For EU countries, see &lt;a href=&quot;https://www.skybrary.aero/index.php/Classification_of_Airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;Classification of Airspace&lt;/a&gt; at SKYbrary.&lt;/p&gt;&#xA;&lt;p&gt;Civil ATC determines the aircraft location and altitude by interrogating a &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_%28aeronautics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;transponder&lt;/a&gt; on-board the aircraft, from the ground. Should the aircraft transponder be not cooperative, ATC might have access to a &lt;a href=&quot;http://www.radartutorial.eu/02.basics/PSR%20vs.%20SSR.en.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;primary radar&lt;/a&gt;, and perform traditional echo measurement, which is less accurate. Primary radar stations are usually operated by military.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EQg85.jpg&quot; alt=&quot;Typical ATC room&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Typical ATC room, source: &lt;a href=&quot;http://learntoflyhere.com/2013/05/03/question-authority-and-atc&quot; rel=&quot;nofollow noreferrer&quot;&gt;Learn To Fly Here&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/questions/25169/what-is-a-tracon&quot;&gt;What is a TRACON?&lt;/a&gt; for a full description of control rooms in the US.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;ATC is definitely a difficult four-dimension task done using 2D displays. Mistakes are made, most of the time they are fixed in time. In the picture below, VRG231 is descending from FL370 while the facing and climbing DCA337 is through FL262. ATC evaluates they will cross safely, but overlooks the closer XCM3018 approaching from the right at FL360 (more details &lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/38.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;at SKYbrary&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zG38n.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zG38n.png&quot; alt=&quot;ATC loss of separation&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Loss of separation conditions in place: VRG231 is descending. ATC takes DCA337 into account, but overlooks XCM3018, &lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/38.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Additional on-board equipment can be used for actual nearby aircraft detection. Such collision avoidance system, known as (&lt;a href=&quot;https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TCAS or ACAS&lt;/a&gt;), detects transponder-equipped aircraft, typically only within a few minutes radius by using a technique similar to ATC interrogation. In addition, TCAS can provide coordinated conflict resolution advisories to the pilots, to increase separation and prevent collision.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WtaNl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WtaNl.jpg&quot; alt=&quot;B737 TCAS&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;B737 TCAS (TA/RA positions on the transponder panel). &lt;a href=&quot;http://www.b737.org.uk/communications.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;C: Navigation&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;After the two first tasks of the crew (aircraft in safe flight and collision risks under control), it's time to look at how the crew can reach the destination.&lt;/p&gt;&#xA;&lt;p&gt;Navigational radio aids are positioned at important locations on the ground, and on-board instruments are used to take benefit of them. Today they include &lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR&lt;/a&gt; (relative bearing determination) and &lt;a href=&quot;http://en.wikipedia.org/wiki/Distance_measuring_equipment&quot; rel=&quot;nofollow noreferrer&quot;&gt;DME&lt;/a&gt; (distance determination) for navigation to, from and between airfields. &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-directional_beacon&quot; rel=&quot;nofollow noreferrer&quot;&gt;NDB&lt;/a&gt; are still used, but their decommissioning has started around the world, they are used as long distance and non-precision VOR.&lt;/p&gt;&#xA;&lt;p&gt;Extract from &lt;a href=&quot;https://en.wikipedia.org/wiki/Nice_C%C3%B4te_d%27Azur_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nice airport&lt;/a&gt; (LFMN, France) documentation for Runway 04 departures. Note how VOR (circled in green) and NDB (magenta) are used as waypoints. Also note how NIZ VOR-DME is used as a reference for relative bearing and distance (green stars).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rcZJu.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rcZJu.png&quot; alt=&quot;Nice airport STAR&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.pht-formation.fr/ops/SID%20STAR/LFMN%20-%20Nice.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Space radio aids, namely &lt;a href=&quot;https://web.stanford.edu/group/scpnt/jse_website/documents/Enge-Aviation_Benefits_from_GNSS.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;GNSS&lt;/a&gt; (US GPS, EU Galileo, Russian Glonass...) are complementing or replacing ground aids for operations (ground aids are still used and required by regulation). For example, the same departures from Nice using &lt;a href=&quot;https://www.skybrary.aero/index.php/Precision-Area_Navigation_(P-RNAV)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Precision Area Navigation&lt;/a&gt; (P-RNAV) taking advantage of GNSS, inertial and ground aids to obtain a precise combined position:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VGbsW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VGbsW.png&quot; alt=&quot;Nice airport STAR GNSS&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.pht-formation.fr/ops/SID%20STAR/LFMN%20-%20Nice.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Waypoints are not referring to any ground aid but defined by their coordinates in the flight management system database. Same source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;A manual or an automated landing can be conducted with the guidance of an &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS&lt;/a&gt; (instrument landing system), which is a radio lighthouse usable to follow proper direction and proper slope:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C5ivt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C5ivt.png&quot; alt=&quot;ILS principle&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;ILS principle (magenta clues displayed on the pilot panel)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;As you may have noticed, contrary to a persistent belief, pilots don't rely on ATC for navigation (the exception would be when a pilot has lost all instrumental references. ATC may usually be able to provide a position if the transponder is still operational).&lt;/p&gt;&#xA;&lt;p&gt;In busy terminal airspace, typically around large airports, ATC role is extended. First, the risk of collision being large and airports being in densely populated areas, aircraft must follow more constrained paths, ATC operators constantly monitor these paths and request corrections from pilots when necessary. Second, runways are scarce resources, arriving aircraft (and departing aircraft to a certain extent) must be sequenced (e.g. by adjusting their speed) into orderly and dense landing queues.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;D: Position awareness&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Current horizontal position has been determined for a long time using VOR and DME and geometry: angle-angle (aka triangulation) or angle-distance equations.&lt;/p&gt;&#xA;&lt;p&gt;Larger aircraft have also used &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_data_inertial_reference_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;inertial platforms&lt;/a&gt; which are able to provide no only the current position, but also the heading, the ground speed and most uniquely the acceleration, the rate of rotation and the attitude (from which the angle of attack can be obtained).&lt;/p&gt;&#xA;&lt;p&gt;Today, those technologies are complemented by GNSS which is able to provide the current position and altitude.&lt;/p&gt;&#xA;&lt;p&gt;The inertial platforms are still used for their complete independence from any external resource, and their precision which is better than GNSS in the short time. Their big con is they drift continuously and must be reset at intervals (e.g. using GNSS data). To take advantage of everything available, sources are often mixed to provide weighted values and cross checking (add to this air sensors providing altitude and airspeed data).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Rjh64.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rjh64.gif&quot; alt=&quot;B737 FMC Current Position page&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;B737 Fight Management Computer page showing current position according to several sensors. &lt;a href=&quot;http://www.b737.org.uk/navigation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Aircraft are also equipped with ground detection, to help prevent so-called &lt;a href=&quot;https://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot; rel=&quot;nofollow noreferrer&quot;&gt;&amp;quot;CFIT&amp;quot;, controlled flight into terrain&lt;/a&gt;. This sensor is based on on-board radar and stored maps and display ground obstacles around. It is used for horizontal monitoring (hill, mountain) as well as vertical monitoring (ground proximity during landing). Such systems are known as &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_proximity_warning_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;EGPWS, enhanced ground proximity warning system.&lt;/a&gt;. They warn pilots by loud advisories, e.g. &amp;quot;Terrain! Terrain, pull up!&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BtnFq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BtnFq.png&quot; alt=&quot;VSD/EGPWS display on Boeing aircraft&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;VSD/EGPWS display on Boeing aircraft, &lt;a href=&quot;http://www.vitzethum.de/displays/gallery/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;2. Regulation point of view&lt;/h3&gt;&#xA;&lt;p&gt;Visibility conditions are determined to be either visual (good visibility) or instrument (insufficient visibility) and there are two sets of rules when flying (visual and instrument). Flying in instrument conditions requires by regulation to perform the flight under instrument rules.&lt;/p&gt;&#xA;&lt;p&gt;Flying with reference to instruments only, requires:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pilot has received the proper training,&lt;/li&gt;&#xA;&lt;li&gt;The specific equipment is available in the aircraft, and on the ground,&lt;/li&gt;&#xA;&lt;li&gt;ATC is provided from the ground.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;VMC vs. IMC&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;There is a set of minimum conditions to declare that the outside environment is visible: these conditions are known as &lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_meteorological_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Visual Meteorological Conditions&lt;/a&gt; (VMC).&lt;/p&gt;&#xA;&lt;p&gt;When VMC are not achieved, the conditions are said to be IMC, for &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Meteorological Conditions&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;VMC criteria depends on countries and airspace, though ICAO provides international recommendations, e.g. in France, generally:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Minimum horizontal visibility 5 km (8 km above FL100).&lt;/li&gt;&#xA;&lt;li&gt;Minimum distance to clouds: Horizontally 1.5 km, vertically 1,000 ft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;VFR vs. IFR&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Any flight must be done under one of the two existing sets of rules:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Visual Flight Rules&lt;/a&gt; (VFR)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Flight Rules&lt;/a&gt; (IFR).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The rules to be followed are dictated by regulation and are directly dependent on the meteorological conditions.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In VMC, both VFR and IFR flight are allowed.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In IMC, only an IFR flight is allowed, the pilot must be qualified to perform IFR and the aircraft must be certified for IFR.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Related:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Spatial_disorientation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Spatial disorientation&lt;/a&gt; which may lead to &lt;a href=&quot;https://aviation.stackexchange.com/q/12234/3201&quot;&gt;fly upside down&lt;/a&gt; without knowing. &lt;a href=&quot;https://aviation.stackexchange.com/q/39342/3201&quot;&gt;Related training&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-10-25T19:40:29.347" LastActivityDate="2020-10-25T19:40:29.347" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12218" PostTypeId="2" ParentId="12199" CreationDate="2015-01-30T12:46:21.463" Score="6" Body="&lt;p&gt;Sunglasses are not absolutely necessary when flying. I have flown the Cessna 172 with regular glasses only, and encountered no difficulty looking outside and inside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the area is covered with snow, it is better to wear glasses to protect the eyes though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're flying during sunrise or sunset, better get them. On the Cessna 172, there is a shield (similar to that in cars) that can be unfolded from above if you encounter strong sunlight:&lt;img src=&quot;https://i.stack.imgur.com/4Mfe0.jpg&quot; alt=&quot;Cessna approaching KSBA Rwy 25 during sunset&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although, some times even the pros can't bear it:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/CNTpH.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-01-30T12:46:21.463" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12219" PostTypeId="2" ParentId="11332" CreationDate="2015-01-30T13:20:20.890" Score="7" Body="&lt;p&gt;While this question already has an answer as to why the VC-25 has not been replaced yet, it does not address the question of why the VC-25 was based off the 747-200 in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you mention, the aircraft entered service in 1990, however its first flight was back in 1987. This was before the -400 took flight, so this could not have been considered. The VC-25 featured a lot of modifications, none of which had been done before on a 747. A long period of planning would need to go into this, so the program launch and initial order would probably have begun a good few years before this date. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are therefore looking at an order date of around 1985, shortly after the introduction of the -300. The -300 offered a number of benefits over the -200, such as greater capacity and improved operating economics. Capacity would not be of much benefit to the VC-25 program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the timescales, the -200 would be nearing the end of production, so these would have been some of the last -200s off the line. Boeing may well have offered a good deal on these now superseded aircraft. The discounts offered would have gone a long way to offset any increase in operating costs, especially due to how infrequently the aircraft operates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is probably why the -200 was chosen. There was simply no benefit of operating the -300, and overall program costs would have likely been higher.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastEditorUserId="1467" LastEditDate="2015-01-30T13:21:56.890" LastActivityDate="2015-01-30T13:21:56.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12220" PostTypeId="1" AcceptedAnswerId="12250" CreationDate="2015-01-30T14:28:01.660" Score="10" ViewCount="1624" Body="&lt;p&gt;Let's say that I have an Italian PPL licence and with my I- registered aircraft (small Cessna example) I want to fly in the US or in Argentina, then ICAO rules allow me to do that. &lt;strong&gt;Am I correct?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I think ICAO rules let you fly in another ICAO country if you have your licence and aircraft from same country)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that, would I be able to do the same thing if my aircraft is registered in &lt;strong&gt;another&lt;/strong&gt; EASA country like Germany (D- registration)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a final question:  What if instead of PPL and Cessna, we put EASA glider licence and a glider? &lt;/p&gt;&#xA;" OwnerUserId="7072" LastEditorUserId="19" LastEditDate="2015-01-30T14:49:35.857" LastActivityDate="2015-01-30T22:32:39.983" Title="May I fly an aircraft registered in an EASA member with an EASA licence (NOT same country as airplane) outside Europe?" Tags="&lt;glider&gt;&lt;ppl&gt;&lt;easa&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12221" PostTypeId="2" ParentId="12205" CreationDate="2015-01-30T15:14:33.607" Score="23" Body="&lt;p&gt;In commercial operations the vigilance to avoid complacency is derived from multiple reinforcing actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Checklists are often preceded by flows in which you take a logical route through the aircraft panels and perform your checks from memory.  These flows are then backed up by the checklist.  Checklists vary in usage. One one end of the spectrum you have silent checks performed by one pilot (e.g. the after takeoff checklist may be a silent checklist) and on the other end you have challenge and response checklists where one pilot reads each item and the pilot who accomplished that action reads the status of that system (e.g. you look at the button/light/etc and call its status rather than calling the response from rote memorization).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an airline cockpit you might fly with the same pilot all month or you may change pilots every trip or sometimes multiple times during a trip.  Flying with many different people helps you standardize on these actions as you cannot &quot;get comfortable&quot; with a specific person.  Everyone expects everyone else to do the checklists properly and if you don't do it you will get called out.  Particularly as a new first officer if you are not doing checklists you are going end up explaining why to the chief pilot and/or training department.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might then ask why we care so much about policing eachother to maintain checklist usage.  The FAA (in the USA) has made a big deal about checklist usage on every checkride you've taken to get into an airline cockpit (at least if you've done your training in the last decade).  It has been drilled into you from the beginning of your training.  In an airlne environment you will have recurrent checkrides every 6-12 months and captains will have line checks every year and proper checklist usage is among the most basic requirement to pass these checks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, every year we sit through a day of crew resource management training and part of that day involves looking at past accidents and understanding what the first thing was that set the accident events in motion (pilot error!).  These often serve as vivid examples of how bad things can get if you start ignoring the checklists (among other things).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-01-30T15:30:01.637" LastActivityDate="2015-01-30T15:30:01.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12222" PostTypeId="2" ParentId="12199" CreationDate="2015-01-30T15:29:56.697" Score="10" Body="&lt;p&gt;There are two main issues here: brightness, and UV protection. For brightness, it's really no different from being in a car. If the weather is cloudy or just not very bright then you won't need sunglasses in order to see. But if the sun is very bright, if you're flying over water or snow, or into the setting sun etc. then you would need them to see in exactly the same way that you would need them in a car (or on a boat) in similar conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The UV question depends on the aircraft. Light aircraft windows are &lt;a href=&quot;https://aviation.stackexchange.com/questions/673/what-materials-are-plane-windows-made-of&quot;&gt;not made of glass&lt;/a&gt; and don't offer the same kind of UV protection that &lt;a href=&quot;http://www.skincancer.org/prevention/are-you-at-risk/sun-hazards-in-your-car&quot; rel=&quot;nofollow noreferrer&quot;&gt;most car windows do&lt;/a&gt;. But they still do protect against UV and the bigger concern is &lt;a href=&quot;https://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/2000s/media/200720.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;apparently&lt;/a&gt; with glass windows found in larger aircraft that also fly higher where UV is more intense:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] glass laminate windscreens allowed higher levels of potentially&#xA;  damaging UV-A radiation to be transmitted than did plastic.&#xA;  Professional pilots who routinely fly at higher altitude for longer&#xA;  periods of time than private pilots should take special precautions to&#xA;  protect their eyes from UV exposure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In any case, for one flight it won't matter at all, but if your friend continues to fly then he should really get a pair of sunglasses with UV protection. The FAA has a detailed pilot's guide to sunglasses &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/sunglasses.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as someone has already mentioned, polarized glasses are &lt;a href=&quot;http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/sunglasses.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;not recommended&lt;/a&gt; in aircraft because they prevent you seeing LCD screens clearly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-01-30T16:58:35.093" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12223" PostTypeId="2" ParentId="12205" CreationDate="2015-01-30T15:35:43.760" Score="36" Body="&lt;p&gt;You stay vigilant by having seen things go wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/12216/&quot;&gt;Like Jamiec mentioned&lt;/a&gt; the importance of a proper preflight is drilled into you by your primary instructor from day one in light aircraft, and that mentality carries through all the way up to heavy transport-category aircraft: You want to find any problems you can while you're on the ground, because if you take a problem into the air with you it's a decision you can quickly come to regret.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I've found all sorts of &quot;interesting&quot; things on preflight inspections of light aircraft, including (but not limited to):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mud wasps building a nest in the pitot tube&lt;/li&gt;&#xA;&lt;li&gt;Mud wasps building a nest in the fuel drain&lt;br&gt;&#xA;(still don't know what was up with that)&lt;/li&gt;&#xA;&lt;li&gt;Missing screws from a fairing&lt;/li&gt;&#xA;&lt;li&gt;Flat-spot on a tire&lt;/li&gt;&#xA;&lt;li&gt;A tennis ball stuffed in between two cylinders&lt;br&gt;&#xA;(a common flight instructor trick to see if students are doing a thorough preflight)&lt;/li&gt;&#xA;&lt;li&gt;Position light lenses installed backwards&lt;br&gt;&#xA;(another common CFI trick, but this one was actually a maintenance shop screw-up)&lt;/li&gt;&#xA;&lt;li&gt;Various light bulbs burned out&lt;/li&gt;&#xA;&lt;li&gt;Water in the fuel after a heavy storm.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've also heard some scary stories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Migrating colony of bees hanging out on the tail of the aircraft&lt;br&gt;&#xA;(described as &quot;The tail was literally &lt;em&gt;dripping&lt;/em&gt; bees&quot;)&lt;/li&gt;&#xA;&lt;li&gt;Flight controls rigged backwards&lt;/li&gt;&#xA;&lt;li&gt;Big gouge in the wingtip&lt;br&gt;&#xA;(acquired by the previous pilot scraping the tip against another plane's tail taxiing in on the ramp)&lt;/li&gt;&#xA;&lt;li&gt;The ever-classic &quot;ran out of fuel because you didn't visually check the tanks&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-03-09T21:19:59.520" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12224" PostTypeId="1" CreationDate="2015-01-30T16:52:00.730" Score="2" ViewCount="7202" Body="&lt;p&gt;What would happen to the rudder of an A320 if both Flight Augmentation Computer (FAC) systems completely failed during mid-flight? Would the auto pilot immediately pass control back to the pilots or if they  failed would that be it? Would it be impossible for the cockpit to communicate with the mechanisms which control the rudder or is manual operation possible in an A320? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I know this maybe a more difficult/impossible questions but what would cause the malfunction of one of the FAC computers? Are there any likely scenarios or previous cases? &lt;/p&gt;&#xA;" OwnerUserId="7077" LastEditorUserId="167" LastEditDate="2015-01-31T05:26:52.373" LastActivityDate="2016-05-24T06:04:44.993" Title="What would happen to the rudder on an A320 if both FAC systems failed?" Tags="&lt;airbus-a320&gt;&lt;aircraft-failure&gt;&lt;fly-by-wire&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12225" PostTypeId="2" ParentId="12224" CreationDate="2015-01-30T17:36:30.073" Score="7" Body="&lt;p&gt;The A320 has a mechanical link from the rudder pedals to the hydraulic rudder actuators. Computer-generated rudder commands for yaw damping and turn coordination are &lt;em&gt;added&lt;/em&gt; to the mechanical signal from the rudder pedals, but in the event of a two-sided computer failure the rudder can still be controlled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The elevator trim wheels are also mechanically connected, so rudimentary control of the aircraft remains even in the event of a total electronic failure, as long as there's hydraulic power.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-01-31T00:17:10.727" LastActivityDate="2015-01-31T00:17:10.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12226" PostTypeId="2" ParentId="12149" CreationDate="2015-01-30T17:39:26.043" Score="4" Body="&lt;p&gt;Airplanes can slow down in a variety of ways.  The most common is actually to pull the nose up and start climbing - it trades the energy of velocity for height and avoides the object in front of you.  Think of what happens when you are riding a bicycle up a hill and stop pedalling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing the throttle allows the friction of the air the plane is moving through to slow the airplane as well.  Think of putting a car in neutral while driving on level ground.  If the pilot doesn't also raise the nose of the plane as it slows down, the loss of airspeed over the wings will result in a reduction of lift and the plane will start descending and the reduced altitude will help avoid an airborn object.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of flaps will increase both drag and lift of the wings.  It will slow the airplane and cause a change in altitude which the pilot can manage by slightly lowering the nose as the flaps go down.  However, flaps have a maximum extension speed (often well below cruise speeds) so they aren't practical for obstacle avoidance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilers disrupt the airflow over the top of the wings to reduce lift.  They have a side effect of increasing drag but it's less of an impact than the loss of lift.  The primary purpose of spoilers is to increase the approach angle to the runway without changing airspeed or attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With this many options, the real answer to obstacle avoidance isn't slowing down: it's steering around.  Going left, right, up or down to avoid the obstacle is much more effective and is what all pilots are taught and what all automated collision avoidance systems use.&lt;/p&gt;&#xA;" OwnerUserId="7079" LastActivityDate="2015-01-30T17:39:26.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12227" PostTypeId="1" AcceptedAnswerId="12228" CreationDate="2015-01-30T18:04:33.053" Score="9" ViewCount="13062" Body="&lt;p&gt;What are the different aircraft regulatory categories aircraft defined by the FAA? Are there any exceptions?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-01-30T18:34:08.217" LastActivityDate="2019-08-25T02:58:58.520" Title="What are the regulatory categories of aircraft defined by the FAA?" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;&lt;transport-category&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12228" PostTypeId="2" ParentId="12227" CreationDate="2015-01-30T18:04:33.053" Score="11" Body="&lt;p&gt;The FAA defines several different types of aircraft, which have different applicable regulations. For fixed-wing aircraft, airworthiness for normal, utility, acrobatic, and commuter categories is covered in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.23&quot;&gt;Part 23&lt;/a&gt;.&#xA;&lt;sub&gt;Note: Seat number excludes pilot seats. Weights are maximum certificated takeoff weights.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Normal category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 9 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 12,500 lb or less&lt;/li&gt;&#xA;&lt;li&gt;Allowed maneuvers:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any maneuver incident to normal flying;&lt;/li&gt;&#xA;&lt;li&gt;Stalls (except whip stalls); and&lt;/li&gt;&#xA;&lt;li&gt;Lazy eights, chandelles, and steep turns, angle of bank 60 degrees or less&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Utility category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 9 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 12,500 lb or less&lt;/li&gt;&#xA;&lt;li&gt;Allowed maneuvers:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Normal category, plus:&lt;/li&gt;&#xA;&lt;li&gt;Spins (if approved for the particular type of airplane); and&lt;/li&gt;&#xA;&lt;li&gt;Lazy eights, chandelles, and steep turns, or similar maneuvers, angle of bank can be more than 60 degrees but not more than 90 degrees&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Acrobatic category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 9 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 12,500 lb or less&lt;/li&gt;&#xA;&lt;li&gt;Allowed maneuvers:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Anything not prohibited due to flight tests&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Commuter category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 19 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 19,000 lb or less&lt;/li&gt;&#xA;&lt;li&gt;Engines: 2 or more&lt;/li&gt;&#xA;&lt;li&gt;Allowed maneuvers:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any maneuver incident to normal flying;&lt;/li&gt;&#xA;&lt;li&gt;Stalls (except whip stalls); and&lt;/li&gt;&#xA;&lt;li&gt;Steep turns, angle of bank 60 degrees or less&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except for commuter category, airplanes may be type certificated in more than one category if the requirements of each requested category are met.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Beyond commuter category, there is the &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/transport/&quot;&gt;transport category&lt;/a&gt;. Multi-engine airplanes satisfying either of the below requirements must be certified in this category. Airworthiness for the transport category is covered in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.25&quot;&gt;Part 25&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Transport category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 20 or more&lt;/li&gt;&#xA;&lt;li&gt;Weight: more than 19,000 lb&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For rotorcraft, there are two main categories: normal and transport. Airworthiness for the normal category is covered in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.27&quot;&gt;Part 27&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Normal category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 9 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 7,000 lb or less&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Multi-engine rotorcraft satisfying these conditions may be certified under transport Category A (see below) if they satisfy certain conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airworthiness for the transport category is covered in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.29&quot;&gt;Part 29&lt;/a&gt;. There are sub-categories here as well.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Transport category&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Category A&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 10 or more&lt;/li&gt;&#xA;&lt;li&gt;Weight: more than 20,000 lb&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Category B&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seats: 9 or less&lt;/li&gt;&#xA;&lt;li&gt;Weight: 20,000 lb or less&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If a rotorcraft only satisfies one of the requirements for Category A, it may be certificated under Category B with certain additional requirements.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A multiengine rotorcraft may be type certificated as both Category A and Category B with appropriate and different operating limitations for each category.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There is also a &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/balloons/&quot;&gt;manned free balloon&lt;/a&gt; category covered in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.31&quot;&gt;Part 31&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A balloon is a lighter-than-air aircraft that is not engine driven, and that sustains flight through the use of either gas buoyancy or an airborne heater.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Part 21 addresses the certification process itself, and includes special types of certificates for other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.21#se14.1.21_124&quot;&gt;Primary category&lt;/a&gt;&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Power sources allowed:&#xA;&lt;ul&gt;&#xA;&lt;li&gt;None&lt;/li&gt;&#xA;&lt;li&gt;Single naturally aspirated engine (stall speed 61 kt or less)&lt;/li&gt;&#xA;&lt;li&gt;Rotorcraft with 6 lb per square foot main rotor discs loading limitation (sea level standard day)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Weight: 2,700 lb or less (seaplanes 3,375 or less)&lt;/li&gt;&#xA;&lt;li&gt;Seats: 3 or less&lt;/li&gt;&#xA;&lt;li&gt;Unpressurized&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The restricted category allows a plane to not meet certain requirements under the normal regulations. The aircraft must meet one of the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.21#se14.1.21_125&quot;&gt;Restricted category&lt;/a&gt;&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Requirements of any regular category, except any that are &quot;inappropriate&quot; for the aircraft's purpose&lt;/li&gt;&#xA;&lt;li&gt;Armed Forces aircraft modified for a special purpose&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;US Armed Forces surplus aircraft can also be certified under one of the below conditions. The FAA has some leeway to waive requirements or add additional ones.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.21#se14.1.21_126&quot;&gt;Surplus aircraft of the Armed Forces&lt;/a&gt;&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Designed and constructed in the US, satisfies certain regulations&lt;/li&gt;&#xA;&lt;li&gt;Counterpart of previously certified civil aircraft, complies with those regulations&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Special certificates are issued for cases where the aircraft is not certified under the regular categories. These allow operation of certain aircraft for certain purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The experimental certificate is for special cases.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Experimental certificates&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Research and development&lt;/li&gt;&#xA;&lt;li&gt;Showing compliance with regulations&lt;/li&gt;&#xA;&lt;li&gt;Crew training&lt;/li&gt;&#xA;&lt;li&gt;Exhibition&lt;/li&gt;&#xA;&lt;li&gt;Air racing&lt;/li&gt;&#xA;&lt;li&gt;Market surveys&lt;/li&gt;&#xA;&lt;li&gt;Operating amateur-built aircraft&lt;/li&gt;&#xA;&lt;li&gt;Operating primary kit-built aircraft&lt;/li&gt;&#xA;&lt;li&gt;Operating light-sport aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/aircraft/gen_av/light_sport/&quot;&gt;light sport&lt;/a&gt; certificate is for light aircraft that may be operated under special conditions. There are 5 categories of LSA.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Light sport certificates&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airplanes&lt;/li&gt;&#xA;&lt;li&gt;Gliders&lt;/li&gt;&#xA;&lt;li&gt;Powered parachutes&lt;/li&gt;&#xA;&lt;li&gt;Weight-shift-control aircraft (commonly called trikes)&lt;/li&gt;&#xA;&lt;li&gt;Lighter-than-air aircraft (balloons and airships)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="679" LastEditDate="2015-01-30T18:33:42.593" LastActivityDate="2015-01-30T18:33:42.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12229" PostTypeId="2" ParentId="12173" CreationDate="2015-01-30T18:06:19.300" Score="2" Body="&lt;p&gt;Headlights on a plane are pretty worthless (other than near the ground).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just as your car headlights don't help you see a mile down the road, headlights on a plane aren't useful for illuminating objects beyond a few hundred yards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is more important that planes, towers, and other obstacles have lights on them to &lt;em&gt;be seen&lt;/em&gt;, not &lt;em&gt;to see&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is why planes have red and green lights (as well as a beacon on top, and a white light on the tail).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, once your eyes adjust to night, you can see plenty from the cockpit.  Starlight, moonlight, and ground-light can give good visibility of terrain, coastlines, clouds, and other things pilots need to see, without any light coming from the airplane.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-01-30T18:06:19.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12230" PostTypeId="2" ParentId="12182" CreationDate="2015-01-30T18:10:43.147" Score="12" Body="&lt;p&gt;First off: I'm not a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe there are two additional issues here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;There is no pilot in the RC helicopter. The forces exerted in some of those maneuvers look pretty extreme, I highly doubt even the most well-trained aerobatics pilot/astronaut/fighter jock would be conscious longer than about 2 minutes into the video you posted. I'm not even sure if they would be able to survive that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scale. All sorts of weird things happen when you scale complex systems up or down. (A famous example is the square-cube law: when you scale a structure up linearly, it's area scales as a square, and its volume (and thus weight) scales as a cube. So, an ant that is 100 times bigger will have feet that are 10000 times bigger but will have to support a weight that is 1000000 times bigger.) For example, the airframe of the RC helicopter is much stronger in relation to its size than it is on a real helicopter. Also, RC models (not just helicopters) are typically ridiculously overmotorized compared to their real-life counterparts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3721" LastActivityDate="2015-01-30T18:10:43.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12231" PostTypeId="2" ParentId="12180" CreationDate="2015-01-30T18:46:00.097" Score="3" Body="&lt;p&gt;Most combat trainers are equipped and rated for IFR.  For example, &lt;a href=&quot;http://www.pilatus-aircraft.com/#39&quot; rel=&quot;nofollow&quot;&gt;Pilatus makes the PC-21&lt;/a&gt;!.&lt;/p&gt;&#xA;" OwnerUserId="7029" LastActivityDate="2015-01-30T18:46:00.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12232" PostTypeId="1" CreationDate="2015-01-30T18:47:05.603" Score="6" ViewCount="1316" Body="&lt;p&gt;There's a clip on YouTube from a pilot of a 747-200 whose TCAS system issues a &quot;confusing&quot; RA:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/-5sA4vPA_6Q?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is happening here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who can't watch the video right now, here are some frames:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K43rx.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/34GRP.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/C3OGN.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5qHl3.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5iv9m.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ej40P.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:09:28.037" LastActivityDate="2015-10-01T19:09:28.037" Title="What's going on in this &quot;confusing&quot; TCAS Resolution Advisory video clip?" Tags="&lt;emergency&gt;&lt;tcas&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12233" PostTypeId="2" ParentId="12232" CreationDate="2015-01-30T18:54:03.633" Score="11" Body="&lt;p&gt;The TCAS responded to the other aircraft not following the flight profile that was observed earlier. If you watch closely, you will see that the other aircraft started to descend as well after the first resolution advisory is given. &#xA;The onboard TCAS responds by issuing the counter-movement to climb immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing that we do not know is what version of TCAS this is supposed to simulate, because newer TCAS systems can interrogate each other and issue resolution advisories not only based on own observed data, but also on data received from the opposite TCAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related Question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1883/how-does-tcas-work&quot;&gt;How does TCAS work?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The entire situation could have been part of the training scenario, as this was done in a simulator, according to the YouTube description:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Practising TCAS RA manoeuvers during our MCC course in a Boeing 747-200 full-flight simulator. This one was quite confusing when the TCAS' voice advised to climb just after having asked to descend.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-01-30T18:54:03.633" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12234" PostTypeId="1" AcceptedAnswerId="12239" CreationDate="2015-01-30T19:04:45.203" Score="10" ViewCount="2803" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/9764/what-happens-when-a-pilot-has-no-instrument-rating-and-visibility-drops#comment19041_9827&quot;&gt;this comment&lt;/a&gt; it's mentioned that pilots in instrument conditions may wind up in a situation where they're inverted due to &lt;a href=&quot;http://en.wikipedia.org/wiki/Spatial_disorientation&quot; rel=&quot;nofollow noreferrer&quot;&gt;spatial disorientation&lt;/a&gt;, and be completely unaware of it until they fly out of the cloud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is that really something that can happen so easily?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2017-10-18T13:08:46.273" Title="Can spatial disorientation in low visibility situations lead a pilot to fly upside down?" Tags="&lt;imc&gt;&lt;night-flying&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12235" PostTypeId="2" ParentId="12173" CreationDate="2015-01-30T19:05:27.657" Score="1" Body="&lt;p&gt;Some advanced systems use infra-red sensors to see in the dark. The combined image is valuable for seeing terrain and runways when approaching an airport. It can also be used en-route to avoid penetrating convective clouds or entering icing conditions at night.&lt;/p&gt;&#xA;" OwnerUserId="7029" LastEditorUserId="5517" LastEditDate="2016-06-02T12:32:44.247" LastActivityDate="2016-06-02T12:32:44.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12236" PostTypeId="2" ParentId="12180" CreationDate="2015-01-30T19:11:45.110" Score="5" Body="&lt;p&gt;Yes: Consider the &lt;a href=&quot;http://www.zlinaircraft.eu/en/Aircraft/Z-242-L-Guru-en/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zlin Z 242&lt;/a&gt;. The &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/90b7d75a300cdb3d86257829005d4563/$FILE/A76EU%20Rev%205.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;type certificate&lt;/a&gt; shows that it is certified in the Acrobatic, Utility, and Normal categories. In the section for Optional Equipment, the aircraft can be sold with &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Communication and navigation equipment VFR DAY, VFR NIGHT OR IFR according to actual requirements of the customers &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally, if the aircraft meets the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1378/what-are-the-faa-requirements-for-an-aircraft-to-be-ifr-certified&quot;&gt;minimum equipment requirements&lt;/a&gt; and inspections, and the POH, Type Certificate or other manufacturer's documents &lt;a href=&quot;https://aviation.stackexchange.com/questions/9651/can-a-cessna-162-skycatcher-be-flown-ifr-in-imc/9664#9664&quot;&gt;allow it&lt;/a&gt;, an aircraft may be flown IFR in IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There would be no particular limitation on operations specifically because the aircraft is capable of aerobatics, but the pilot would still need to follow their clearance. This would significantly limit the benefit of the instrument certification. (Note that even if deviations in altitude and flight path were approved, aerobatics &lt;a href=&quot;https://aviation.stackexchange.com/questions/12179/aerobatics-in-firm-imc-how-would-one-do-it&quot;&gt;still wouldn't really be possible&lt;/a&gt;.)&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-30T19:11:45.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12237" PostTypeId="2" ParentId="12234" CreationDate="2015-01-30T19:27:07.403" Score="2" Body="&lt;p&gt;Yes, very easily... Although 'sideways, nose down and at 200 knots into the ground before becoming a massive fireball' is more common&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's only a short period they may just find themselves coming out of the other side of the cloud at a completely different attitude than they went in (and, likely, altitude too), but with anything more than just a quick cloud, it can be far more serious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots without an instrument license have something like a 3 minute life expectancy once they get into instrument conditions.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-01-30T19:27:07.403" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12238" PostTypeId="2" ParentId="12212" CreationDate="2015-01-30T19:31:19.780" Score="19" Body="&lt;p&gt;The correct answer is that the answer to this question, like many in aviation regulations, varies greatly by country. As &lt;a href=&quot;https://aviation.stackexchange.com/a/12215/755&quot;&gt;SentryRaven's answer&lt;/a&gt; mentions, some countries allow Flight Crew In-seat Rest. However, this is &lt;strong&gt;not&lt;/strong&gt; a universally-allowed practice. In particular, &lt;a href=&quot;http://www.dallasnews.com/news/washington/20091201-FAA-won-t-allow-cockpit-naps-3063.ece&quot; rel=&quot;nofollow noreferrer&quot;&gt;sleeping in the flight deck is never allowed in the U.S.&lt;/a&gt; One (but not both) crew sleeping on the flight deck is allowed in Europe, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What hasn't seemed to have been addressed in the other answers yet is what I would expect (or at least hope) is the much more common situation of pilots sleeping on board: &lt;strong&gt;augmented flight crews&lt;/strong&gt;. An &quot;&lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/F9E8B27D6AFF4FCE86256DBB006C3468?OpenDocument&amp;amp;Highlight=sleep&quot; rel=&quot;nofollow noreferrer&quot;&gt;augmented flight crew&lt;/a&gt;&quot; is when more pilots are assigned to a flight than the minimum number required to operate the aircraft (which is generally 2 on today's airliners.) This is typically used on long-haul flights, where airlines can have 3 or 4 pilots on board. At least in the context of the U.S., two pilots must remain awake and in the flight deck, but the other 1 or 2 pilots may sleep. This way the crew can rotate flight deck duty and sleep time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/F9E8B27D6AFF4FCE86256DBB006C3468?OpenDocument&amp;amp;Highlight=sleep&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.1061&lt;/a&gt;, 3-pilot crews may operate flights with scheduled flight times up to 12 hours and 4-pilot crews may operate flights with scheduled flight times up to 16 hours. In the case of either a 3-person or 4-person crew, at least two of them must be qualified to fly as pilot-in-command on the aircraft, while the other(s) must be qualified to fly as second-in-command. This ensures that someone qualified to fly as pilot-in-command remains on flight deck duty at all times. In order to use an augmented flight crew, adequate sleeping facilities must be installed on the aircraft for the pilot(s) who are not in the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/1712/755&quot;&gt;this question&lt;/a&gt; give more detail about the crew rest quarters that are common on airliners used on long-haul flights. These exist both for flight crew and for cabin crew, though, from what I understand, these are generally separate from each other.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-29T22:29:26.820" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12239" PostTypeId="2" ParentId="12234" CreationDate="2015-01-30T19:33:13.463" Score="15" Body="&lt;p&gt;The short answer is &quot;Yes&quot;, if the pilot is not properly trained, doesn't trust their instruments, or has an instrumentation failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without a visual reference (such as the real horizon or artificial horizon) it's very easy for a pilot to place their aircraft in an &quot;unusual attitude&quot; -- something other than the expected straight-and-level flight or commanded turn.&lt;br&gt;&#xA;As humans we naturally rely on our inner ear and sense of balance to tell us what's &quot;up&quot; or &quot;down&quot;, but in a moving aircraft you can move through a whole range of attitudes in &quot;1G maneuvers&quot; (where your body thinks down is where your seat is).&lt;br&gt;&#xA;Little micro-movements we unconsciously make on the controls (or larger movements we may make consciously in response to turbulence or other perceved disturbances in the aircraft's attitude) based on what our ears and butts are telling us will eventually get us into trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's so easy that often instructors will have students create their own unusual attitudes in training by having the student close their eyes and simply try to fly straight and level - within a few minutes at most the student will invariably no longer be in level flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There's an exercise you can do on the ground to illustrate how imperfect your sense of balance and direction is, but it requires a large, flat, open area. We'll use an American Football field for this example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Stand on one of the goal lines&lt;/li&gt;&#xA;&lt;li&gt;Have a friend stand at the 50 yard line (about 45 meters away)&lt;/li&gt;&#xA;&lt;li&gt;Close your eyes or put on a blindfold, count to ten, and walk directly toward your friend&lt;/li&gt;&#xA;&lt;li&gt;Stop when you reach your friend (or your friend yells &quot;STOP&quot; because you're about to walk into a goal post)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most people will not make it to their friend on the 50 yard line, because without a visual reference it's very hard to walk a straight line: You will veer off one way or the other, and some folks will even manage to walk in a complete circle (which is what eventually tends to happen over a large enough distance).&lt;br&gt;&#xA;The same principles apply to flight, except there's a third dimension (vertical) to contend with.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2015-01-31T01:32:36.107" LastActivityDate="2015-01-31T01:32:36.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12240" PostTypeId="2" ParentId="12232" CreationDate="2015-01-30T20:11:48.083" Score="9" Body="&lt;p&gt;See below for a description of how the TCAS (Traffic Collision Avoidance System) display is showing another aircraft approaching in each frame:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;900 feet below and climbing&lt;/li&gt;&#xA;&lt;li&gt;800 feet below and climbing&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The traffic advisory (TA) gives the pilots the chance to avoid or at least anticipate conflict&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;500 feet below and still climbing&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The resolution advisory (RA) gives pilots instructions that should prevent a collision between the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The RA tells pilot to descend&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They are level at FL270, so descending will allow the other aircraft to continue climbing above them&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;The TCAS in the other aircraft will tell them to keep climbing&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;500 below and descending&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The RA changes to &quot;climb&quot;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The other aircraft has started descending, contradicting the TCAS instructions&lt;/li&gt;&#xA;&lt;li&gt;The pilot should climb now to avoid the other aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;800 below and climbing&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The RA changes to &quot;adjust vertical speed&quot;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is now more vertical distance between the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The pilot should adjust their vertical speed to remain clear of the traffic&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;700 below and climbing&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Clear of conflict&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft have passed each other by this point, without colliding, so TCAS and the pilots worked together to prevent (simulated) disaster&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The TCAS display shows other aircraft as shapes depending on proximity and the risk of collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yEIHc.png&quot; alt=&quot;TCAS symbology&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://code7700.com/g450_tcas.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The symbols in the simulator from the video are slightly different, but you can see the aircraft go from non-threat (first frame), to traffic advisory (second frame), to resolution advisory (third and fourth frames).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the symbol, basic information about the aircraft's altitude is displayed. The numbers represent the difference in altitude in hundreds of feet (negative means below your aircraft), and the arrow represents climb or descent over 500 feet per minute. See &lt;a href=&quot;https://www.l-3avionics.com/products/skywatch/how-it-works.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for info about the symbols.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-01-30T20:11:48.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12241" PostTypeId="2" ParentId="12234" CreationDate="2015-01-30T20:36:44.867" Score="6" Body="&lt;p&gt;Yes. Remember that once you get into a weird position, like upside down, you may be turning at the same time, creating a false gravity, so it does not feel like you are upside down. Usually you just feel &quot;cockeyed&quot;, and if you try to adjust based on that &quot;feeling&quot;, you will make the WRONG input which will make the situation worse. If you strap yourself inside a ball in an amusement park and get turned upside down, even then it can be difficult to tell exactly what is going on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many pilots have difficulty trusting their instruments and have to be trained to do so very strictly. When I was put &quot;under the hood&quot; for the first time, my instructor told me &quot;you will go into a spin&quot;. I said &quot;no I will not&quot;. He said, &quot;Yes you will, everybody does the first time.&quot; As a matter of fact I kept the plane straight and level and did not go into a spin, but I was an exceptional case, 95% of students will start spinning the aircraft uncontrollably if they cannot see the horizon. JFK, Jr. was killed that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me just say, that first time under the hood I was sweating bullets and focusing my mind like I was trying to play speed chess against Bobby Fischer. Flying by instrument is INSANELY hard, if you have not trained on it for hours and hours. You have 5 different needles that you have to keep lined up at the same time. Even experienced pilots find manual instrument flying grueling and mentally taxing (thank god for autopilot).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="19381" LastEditDate="2017-10-18T13:08:46.273" LastActivityDate="2017-10-18T13:08:46.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12242" PostTypeId="1" CreationDate="2015-01-30T20:42:25.550" Score="10" ViewCount="12013" Body="&lt;p&gt;How much does Earth's rotation affect flight times in going East or West, and how could you calculate if zero winds?&lt;/p&gt;&#xA;" OwnerUserId="7085" LastEditorUserId="65" LastEditDate="2015-01-30T21:33:24.077" LastActivityDate="2015-02-01T16:45:02.390" Title="How Earth's rotation affect flight times?" Tags="&lt;weather&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ClosedDate="2015-12-17T12:30:30.790" ContentLicense="CC BY-SA 3.0" />
  <row Id="12243" PostTypeId="2" ParentId="12242" CreationDate="2015-01-30T20:51:10.470" Score="5" Body="&lt;p&gt;It affects flight time the same way that it affects driving time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cars measure their speed over the ground based on wheel speed. Airplanes can measure their speed over the ground using things like GPS. Either way, it's referenced to the ground. Technically the ground is moving, but it's not perceptible to us and we still would say zero speed means not moving over the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes primarily measure their speed through the air (airspeed), and the air tends to move with the ground, so the situation is the same. If the air is not moving the same as the ground, it's called wind, &lt;a href=&quot;https://aviation.stackexchange.com/questions/2549/why-do-flight-times-differ-between-traveling-east-versus-traveling-west&quot;&gt;which is the primary influence on flight time&lt;/a&gt;. Wind is influenced by the earth's rotation, but the rotation doesn't directly influence flight time.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-01-30T20:51:10.470" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12244" PostTypeId="2" ParentId="12242" CreationDate="2015-01-30T21:05:32.067" Score="12" Body="&lt;p&gt;It does not affect as much as one would think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The atmosphere moves along with Earth's rotation. An airplane taking off from one place on Earth has to move through the atmosphere which is moving with Earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you may ask when does it take longer when we travel from Western Europe to Eastern USA, compared to USA to Europe? That depends on &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_stream&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jet Stream&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Jet streams are fast flowing, narrow air currents found in the atmosphere of ... Earth.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many air routes take advantage of jet streams, as you can see as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TrrOF.jpg&quot; alt=&quot;Jet Streams&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots know about the jet streams and will try to gain benefit of them. Recently, there were some news that a flight from New York to London traveled faster than expected because it was in jet stream (details &lt;a href=&quot;http://rt.com/news/221559-boeing-supersonic-heathrow-airplane/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://mashable.com/2015/01/08/jet-stream-new-york-london-flights/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you want to know why Earth's atmosphere moves with it, &lt;a href=&quot;https://physics.stackexchange.com/q/1193/38447&quot;&gt;please see this&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a &lt;a href=&quot;https://physics.stackexchange.com/q/16390/38447&quot;&gt;similar question on Physics.SE&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2015-01-30T21:05:32.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12245" PostTypeId="2" ParentId="12220" CreationDate="2015-01-30T21:21:26.533" Score="2" Body="&lt;p&gt;By treaty, if you are flying Italian-registered aircraft you cannot be legally denied to fly virtually anywhere in the world, including the United States. Some countries will try to bully you into taking tests, especially for instrument flying, but whether this would hold up in court is dubious. Treaty law is very powerful, at least in the United States, and in a US Federal Court, if you can cite treaty, it completely overrules any FAA &quot;regulations&quot;. For this reason, it is EXTREMELY rare for the FAA to question a foreign pilot's credentials, because they know if it went to court they could get their ass kicked for treaty violations, which is taken very seriously by Federal judges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying a foreign-registered aircraft (not your own country), you need to have a license from that country (in this case Germany), or from the United States. You can &quot;convert&quot; your Italian license into a US one, but the process is a pain in the ass and takes several months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For gliders it is the same deal as a powered aircraft. As long as it is an Italian glider you are good to go. For US gliders it completely depends on where you are getting the glider from. For example, at our club there is a French guy who is an expert glider pilot, but the instructors at our club will not let him fly the club gliders. They are giving him check ride after check ride. He spent the whole summer in &quot;check rides&quot;. It was a joke because he was a better glider pilot than a lot of the instructors. He probably would have been better off going through the hassle of getting a conversion.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-30T21:21:26.533" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12246" PostTypeId="2" ParentId="2042" CreationDate="2015-01-30T21:31:32.853" Score="3" Body="&lt;p&gt;The biggest factor in landing gear length is going to be how the engine(s) is/are mounted and ensuring they have clearance.  The C-130 and turbo-prop commuter airliners (Embraer and Bombardier) have the engines in line with the bottom of the wing which is attached to the top of the fuselage.  Large airliners (Airbus and Boeing) have engines slung well under the wings which attach near the bottom of the fuselage.  The turbo props get a lot of clearance from the height of the fuselage while the jets rely on longer gear legs.&lt;/p&gt;&#xA;" OwnerUserId="7079" LastActivityDate="2015-01-30T21:31:32.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12247" PostTypeId="2" ParentId="12205" CreationDate="2015-01-30T21:35:48.747" Score="-2" Body="&lt;p&gt;On commercial flights, key checklist items are forced by using a procedure call a &quot;cross check&quot;. The one pilot must &quot;challenge&quot; another for those specific check list items. For non-cross checked items, pilots have discretion to implement checklists as they see fit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each pilot has their own practice. Some are sloppy and do nothing. Others fastidiously follow every item. Most commercial pilots tend to blow off most checklist items, especially anything outside the cockpit. For example, I fly American a lot and when the flight crew arrives I always watch to see if they do a walkaround and I have NEVER seen them do it. I complained about this to one of the top flight instructors at American and he said, &quot;Well, they are supposed to do the walkaround.&quot; Yeah, they are SUPPOSED to, but do not do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It comes down to the personal discipline and attitudes of the pilot involved and how pressured they are to get the plane up in the air and on schedule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On non-commercial flights and cargo flights often crews will become very lax. For example, in 2014 a Gulfstream crashed at Hanscom airfield killing everyone on board because they tried to takeoff with a gust lock engaged. This is impossible if you do even a minimal checklist because a control check is like the #1 or #2 thing on any checklist. A review of the tape showed that the crew in that case did ABSOLUTELY NOTHING verbal for cross checking. Furthermore, a review of the flight recorder for the aircraft showed that the crew had NEVER done a control check in 98% of the flights in that aircraft. Such laxity is not unusual in non-commercial flights.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-26T23:43:18.507" LastActivityDate="2015-10-26T23:43:18.507" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="12248" PostTypeId="2" ParentId="12199" CreationDate="2015-01-30T21:41:41.067" Score="2" Body="&lt;p&gt;It is just like driving out in the open, like on a desert highway. If you would not mind driving for an hour and a half on a desert highway in the midday summer sun, then you will have no problem during your lesson.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-01-30T21:41:41.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12249" PostTypeId="2" ParentId="12234" CreationDate="2015-01-30T21:41:45.117" Score="7" Body="&lt;p&gt;Yes, definitely. This is from &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/GeneratePDF.aspx?id=CEN11LA164&amp;amp;rpt=fa&quot; rel=&quot;nofollow noreferrer&quot;&gt;an NTSB accident report&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During the right turn, the pilot stated that he looked to his right&#xA;  to cross check the GPS and set up the autopilot for a coupled&#xA;  approach. He felt the airplane start to accelerate rapidly, and he&#xA;  looked back to the Primary Flight Display (PFD) which was “showing all&#xA;  brown with no sky and 6-7 chevrons, indicating a severe unusual&#xA;  attitude.” He tried to correct the unusual attitude, but said that he&#xA;  had severe vertigo, and was unable to regain control of the airplane.&#xA;  He elected to deploy the ballistic recovery parachute, and the&#xA;  aircraft impacted terrain in a nose low attitude in a creek bed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The roll wasn't fully inverted, but it was extreme (120 degrees to the left):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The downloaded data showed that, just prior to the accident, the&#xA;  airplane went through a series pitch and roll oscillations, with&#xA;  maximum pitch values of approximately 26 degrees nose up, and 75&#xA;  degrees nose down. The airplane reached maximum roll values of&#xA;  approximately 83 degrees right wing down, and 120 degrees left wing&#xA;  down.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, it's absolutely possible for the aircraft to end up in an extreme attitude very quickly and easily: in this case the pilot just looked away to set the autopilot. The reasons why this can happen so easily have been discussed and commented in detail in &lt;a href=&quot;https://aviation.stackexchange.com/questions/9764/what-happens-when-a-pilot-has-no-instrument-rating-and-visibility-drops&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-01-30T21:41:45.117" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12250" PostTypeId="2" ParentId="12220" CreationDate="2015-01-30T22:32:39.983" Score="3" Body="&lt;p&gt;Under &lt;a href=&quot;http://www.icao.int/safety/airnavigation/Pages/peltrgFAQ.aspx#anchor08&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO rules&lt;/a&gt;, if Germany 'validates' your Italian license then yes, you can fly the German aircraft in other countries:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Use of flight crew licences on foreign-registered aircraft&lt;/p&gt;&#xA;&lt;p&gt;Any pilot&#xA;who wishes to fly on an aircraft registered in a State other than the&#xA;one that has issued the licence, needs to obtain an authorization from&#xA;the State of Registry. This authorization is generally given by the&#xA;State of Registry through a validation or a conversion of the foreign&#xA;licence. In general, the validation process is used for short-term&#xA;authorization while the conversion process is used for longer-term&#xA;authorization.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;What 'validation' means here is up to the country where the aircraft is registered. ICAO itself doesn't define what they should do:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When a State validates a foreign licence, it recognizes it as valid&#xA;for use on aircraft on its own registry. The Convention on&#xA;International Civil Aviation and its Annex 1 do not contain specific&#xA;requirements for the validation of licences beyond establishing the&#xA;principle and the fact that the validity of a validation, cannot be&#xA;extended beyond the validity of the supporting licence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the US specifically, these ICAO rules are implemented in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_13&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.3&lt;/a&gt; (emphasis mine):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;(b) Required pilot certificate for operating a foreign-registered&#xA;aircraft within the United States.&lt;/em&gt; No person may serve as a required&#xA;pilot flight crewmember of a civil aircraft of foreign registry within&#xA;the United States, unless—&lt;/p&gt;&#xA;&lt;p&gt;(1) That person's pilot certificate or document issued under §61.29(e)&#xA;is in that person's physical possession or readily accessible in the&#xA;aircraft when exercising the privileges of that pilot certificate; and&lt;/p&gt;&#xA;&lt;p&gt;(2) Has been issued in accordance with this part, or has &lt;strong&gt;been issued&#xA;or validated by the country in which the aircraft is registered&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Practically speaking, I would say that if you have some official piece of paper from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Luftfahrt-Bundesamt&quot; rel=&quot;nofollow noreferrer&quot;&gt;German authorities&lt;/a&gt; confirming that you are authorized to operate German aircraft - or at least &lt;em&gt;this&lt;/em&gt; German aircraft - then you're good to go. The piece of paper may even be unnecessary as far as Germany is concerned, but if you plan on flying internationally then I think the more pieces of official paper that you have, the better.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-01-30T22:32:39.983" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12251" PostTypeId="2" ParentId="8441" CreationDate="2015-01-30T23:00:54.573" Score="1" Body="&lt;p&gt;The Boeing 737NG APU inlet is on the right side of the tail cone and the exhaust is &#xA;Through the tail.&lt;/p&gt;&#xA;" OwnerUserId="7089" LastActivityDate="2015-01-30T23:00:54.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12252" PostTypeId="1" CreationDate="2015-01-31T00:00:10.733" Score="6" ViewCount="498" Body="&lt;p&gt;Under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=84f2720d370d343a965024d4545842e1&amp;amp;n=sp14.2.61.i&amp;amp;r=SUBPART&amp;amp;ty=HTML&quot; rel=&quot;nofollow&quot;&gt;§61.215 Ground instructor privileges&lt;/a&gt;, it says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) A person who holds a basic ground instructor rating is authorized&#xA;  to provide—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Ground training in the aeronautical knowledge areas required for&#xA;  the issuance of a sport pilot certificate, recreational pilot&#xA;  certificate, private pilot certificate, or associated ratings under&#xA;  this part;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Ground training required for a sport pilot, recreational pilot,&#xA;  and private pilot flight review; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) A recommendation for a knowledge test required for the issuance of&#xA;  a sport pilot certificate, recreational pilot certificate, or private&#xA;  pilot certificate under this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But it doesn't say anything about what kind of category and class the ground instructor may instruct on. Is a separate GI rating required for each category and class? or is there one GI rating that covers all categories and classes?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="1696" LastEditDate="2016-07-05T15:02:05.043" LastActivityDate="2016-07-06T01:48:57.560" Title="What categories/classes is a Ground Instructor able to instruct on?" Tags="&lt;faa-regulations&gt;&lt;ground-instructor&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12253" PostTypeId="1" AcceptedAnswerId="12259" CreationDate="2015-01-31T00:43:01.640" Score="10" ViewCount="1416" Body="&lt;p&gt;As a for instance, let's say there are 2 jets going at low airspeeds (close to $V_S$) that get too close to eachother and a TCAS Resolution Advisory callout is announced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would TCAS issue an RA to order one of the jets to climb, resulting in loss of airspeed and a stall?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2017-06-13T01:15:11.853" Title="Would TCAS ever issue a &quot;climb, climb!&quot; RA that would stall a jet with a low airspeed?" Tags="&lt;emergency&gt;&lt;stall&gt;&lt;airspeed&gt;&lt;tcas&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12254" PostTypeId="2" ParentId="12252" CreationDate="2015-01-31T03:18:19.910" Score="4" Body="&lt;p&gt;The basic ground instructor covers everything you quote.  The only additional privileges you can get are those granted by the advanced ground instructor rating.  My ground instructor certificate just says &quot;Ground instructor&quot; on the front and &quot;advanced instrument&quot; on the back.  No other ratings or limitations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things like reading charts, familiarity with regulations, weather information, fundamentals of flight and other required knowledge topics do not depend on category or class of aircraft.  You just need the BGI (and IGI for instrument) to teach ground and endorse written tests regardless of the aircraft the student is or will eventually train in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only other benefit to having a ground instructor certificate is that it is required to get a gold seal on your CFI certificate.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2016-07-05T22:54:34.773" LastActivityDate="2016-07-05T22:54:34.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12255" PostTypeId="2" ParentId="12253" CreationDate="2015-01-31T03:52:17.043" Score="4" Body="&lt;p&gt;I think this is possible. TCAS generates Resolution Advisories based on various factors, and two aircraft equipped with TCAS transponders then coordinate their RAs. Each aircraft knows only the bearing, altitude, and distance of the other aircraft; it gets its data from Mode S transponders, which don't send things like stall speed or maximum climb/descent rate. That's all that the basic TCAS algorithm uses. It doesn't necessarily even know its own plane's performance information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Separate from the basic RA system, an installation can be configured to not issue &quot;Climb&quot; or &quot;Increase Climb&quot; RAs under certain circumstances (each TCAS RA is sufficient to avoid a collision if the other aircraft does nothing, so &quot;Maintain Climb&quot; or &quot;Reduce Descent&quot; or &quot;Do Not Descend&quot; may be enough). This doesn't change the general sense of an RA (climb/descend), but rather modifies the actual RA issued to its own aircrew. However, it does not &lt;em&gt;have&lt;/em&gt; to be configured in such a way, and the configuration won't necessarily catch all stall situations. So a TCAS system is certainly capable of issuing an RA that will stall your plane.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-01-31T03:52:17.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12256" PostTypeId="2" ParentId="12224" CreationDate="2015-01-31T04:00:56.530" Score="0" Body="&lt;p&gt;Only the Rudder has a mechanical link which remains functionnal enough even with electrical commands failure. Landing with it together with engine control only has been tried during certifications. &lt;/p&gt;&#xA;" OwnerUserId="7091" LastEditorUserId="7091" LastEditDate="2015-01-31T04:15:15.717" LastActivityDate="2015-01-31T04:15:15.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12257" PostTypeId="1" AcceptedAnswerId="12263" CreationDate="2015-01-31T05:09:03.537" Score="17" ViewCount="12818" Body="&lt;p&gt;Is it possible that an aircraft could continue to fly and then land safely on a single engine if another stopped working?&lt;/p&gt;&#xA;" OwnerUserId="7031" LastEditorUserId="167" LastEditDate="2015-01-31T05:25:11.877" LastActivityDate="2017-10-18T13:09:00.893" Title="Can an aircraft continue flying and land safely following an engine failure?" Tags="&lt;engine-failure&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12258" PostTypeId="2" ParentId="12257" CreationDate="2015-01-31T05:16:41.450" Score="4" Body="&lt;p&gt;Yes. All two-engine (and three- and four-engine) aircraft are certified to safely land if one engine fails at any point on the route, including even the most critical parts of take-off.&lt;br&gt;&#xA;However, lower engine performance will force a reduced service ceiling. Basically, the plane will have to fly lower, and less efficiently, so often it wouldn't be able to get to its intended destination and instead would have to abort to a nearby airport.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="19381" LastEditDate="2017-10-18T13:09:00.893" LastActivityDate="2017-10-18T13:09:00.893" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12259" PostTypeId="2" ParentId="12253" CreationDate="2015-01-31T05:33:26.060" Score="19" Body="&lt;p&gt;The FAA publishes &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-151A.pdf&quot;&gt;Advisory Circular 20-151A&lt;/a&gt;, which says in section 2-17(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Because TCAS II can only accept a limited number of inputs related to&#xA;  airplane performance, it’s not possible to automatically inhibit CLIMB&#xA;  and INCREASE CLIMB RAs in all cases where it may be appropriate to&#xA;  inhibit such RAs. &lt;strong&gt;In these cases, TCAS II may command maneuvers that&#xA;  may significantly reduce stall margins or result in stall warning&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-01-31T05:33:26.060" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12260" PostTypeId="1" AcceptedAnswerId="12275" CreationDate="2015-01-31T05:51:03.830" Score="8" ViewCount="7613" Body="&lt;p&gt;Generally we fly under the rule of QNH which means our IA is above mean sea level. And as we all know airpace limits are charted in MSL. Then, why the definitions of airspaces are they (class C, D and E) depiceted in AGL?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastActivityDate="2016-04-28T14:04:06.180" Title="Why are airspaces depicted in AGL?" Tags="&lt;airspace&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12261" PostTypeId="1" AcceptedAnswerId="14686" CreationDate="2015-01-31T06:23:50.623" Score="16" ViewCount="18154" Body="&lt;p&gt;Can the bigger planes like B737 do barrel rolling kind of stunts like fighter jets do? I'm sure if it's full of passengers or cargo it would be very difficult and dangerous, but is it possible with an empty aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember &lt;a href=&quot;http://avherald.com/h?article=4428f2f7&quot; rel=&quot;noreferrer&quot;&gt;an All Nippon Airways incident&lt;/a&gt; where the co-pilot did a 131 deg roll by mistake but I don't know if a complete barrel roll is actually possible in large planes?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2018-04-26T01:15:35.947" LastActivityDate="2020-02-26T03:31:04.153" Title="Is it possible to do a barrel roll in a large aircraft like a B737?" Tags="&lt;boeing-737&gt;&lt;aerobatics&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12262" PostTypeId="1" AcceptedAnswerId="12274" CreationDate="2015-01-31T06:29:39.943" Score="14" ViewCount="10018" Body="&lt;p&gt;There is an area called &quot;outer area&quot; near class C airspace. As described by &lt;a href=&quot;http://www.faraim.org/aim/aim-4-03-14-135.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this AIM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Though not requiring regulatory action, Class C airspace areas have a procedural Outer Area. Normally this area is 20 NM from the primary Class C airspace airport. Its vertical limit extends from the lower limits of radio/radar coverage up to the ceiling of the approach control's delegated airspace, excluding the Class C airspace itself, and other airspace as appropriate. (This outer area is not charted.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As it is not charted and there is no FAA regulations about outer area, I would think it could also be set near class B or D airspaces. Why don't any other airspaces but only class C airspace has the outer area?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="14897" LastEditDate="2021-04-13T00:50:06.860" LastActivityDate="2021-04-13T02:22:58.623" Title="Why does only class C airspace have an &quot;outer area&quot;?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;class-c-airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12263" PostTypeId="2" ParentId="12257" CreationDate="2015-01-31T06:30:18.547" Score="26" Body="&lt;p&gt;The answer to your question strongly depends on what kind of airplane you're talking about (in particular, what set of rules it was certificated under), as well as the phase of flight you are in (takeoff vs. cruise vs. approach/landing) and whether you are in a jet or a (turbine or piston) propeller aircraft.  (I'm going to exclude single-engine airplanes from this discussion, as well.)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Cruise Flight&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In general, an engine failure in cruise flight is a manageable emergency unless you are in extremely high terrain in a light twin or some other corner case.  The general procedure is to &quot;drift down&quot; in a slow-ish descent to your single-engine cruise altitude -- if you don't already have a driftdown airspeed worked out, you can use Vyse as a substitute to get a slow driftdown -- and then divert to a nearby suitable airport to get the busted engine looked at, as you'll be flying lower and less fuel-efficiently as a result.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Takeoff&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Takeoff is the most troublesome time for an engine failure to happen, bar none: you are at high gross weight and don't have altitude under you to turn into airspeed and landing options.  What you want to do is get to the pattern altitude, fly a pattern, and land in a reasonably quick, but orderly fashion -- you don't need to ultra-hurry things even if you have an engine on fire, but you do want to get back on the ground in a reasonable timeframe to get things looked at. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Light Twins (cabin class, commuter, pre-FAR 25 airliners)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;These aircraft, unfortunately, struggle in single-engine situations on the best of days, as the certification requirements for single-engine performance in FAR 23 are minimal at best.  The common adage you will hear about light twins, even, is &quot;the second engine will carry you to the scene of the crash&quot; -- it is possible for a light twin to be type certificated with nil or negative worst case single-engine climb performance in the case of an engine failure at or shortly after takeoff.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Business Jets (certificated under FAR 23)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Corporate or business-type light jet aircraft (Citations, Gulfstreams, LearJets, Beechjets, etal) and their turboprop counterparts (such as KingAirs), while often certificated under Part 23, will generally have superior single-engine performance to light twins, although this is by no means guaranteed.  You'll likely get up into the pattern and be able to make a reasonably normal single-engine landing, barring any aggravating factors at least; this is because even the smallest turbine engines are large enough that the aircraft will have some degree of excess thrust as a twin, leaving it with a thrust reserve in a single engine situation.  These aircraft are also flown by pilots with type ratings and a CPL or ATPL, which means they will be more familiar with the performance of that specific aircraft and any aircraft-specific engine-out procedures needed to eke out maximum single-engine climb rates.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Twin-Engine Airliners (transport class twin turboprops and twin jets certified under FAR 25)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The FAR 25 requirements for engine-out takeoff performance are much more stringent than FAR 23, and practically guarantee that the aircraft is capable of positive climb in a V1 cut (engine failure right after decision speed) at maximum takeoff weight.  In addition, V1 cuts are a classic airline training scenario that every airline flight crew on the planet runs in the sim on a regular basis (I wouldn't be surprised if a V1 cut came up every few sim sessions or so, if not every sim session).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a practical sense, this means that unless the aircraft is overloaded or is suffering from something beyond a simple engine failure (I'll talk about that later), an airline flight crew will handle engine failure on takeoff in an airliner as a routine event.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;3 and 4 engine airliners&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;A single engine failure on a three or four engine aircraft is by no means critical, especially on three- and four-engined jet transports.  This doesn't mean that 747 crews don't practice V1 cuts any longer, though!&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Props vs Jets&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Engine failure in a jet, whether it be a T-37 or an A380, is simple: you put appropriate rudder in, ID which engine died (between your instruments and &quot;dead foot, dead engine&quot;, you should have enough data to go on), add power as needed on the working engine (say, if you are doing an assumed/FLEX temp takeoff), and kill the dead engine, then run the rest of the checklist at a leisurely pace now that safe flight is more-or-less assured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller aircraft are a bit more complicated though in that you need to &lt;a href=&quot;https://aviation.stackexchange.com/a/11167/3825&quot;&gt;feather&lt;/a&gt; the dead engine's propeller to keep it from dragging the airplane down -- older constant-speed prop designs such as those on warbirds and piston-engine airliners had FEATHER buttons for this job, one per engine; newer aircraft with constant-speed props have a gate on either the power or the condition levers that serves in place of the feathering button.  You also have more levers to manipulate when adding power to the working engine(s) and killing the dead engine, and may have more difficulty figuring out which engine died without positive flight control responses (I can only imagine how baffling a center engine failure on a Trislander would be!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result of the critical nature of the feathering process, modern (and even some not-so-modern) transport-class (and some other) propeller aircraft have an autofeather or NTS (Negative Torque Sensing) system that will automatically drive the blades of a propeller towards (or even all the way to) the feathered position if it is armed and senses that the propeller is trying to drive the engine.  However, feathering the propeller on an engine that &lt;em&gt;isn't&lt;/em&gt; shut down is also a bad idea as it causes the propeller and engine to overspeed due to the airloads the engine was driving going away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if you are in a light twin with fixed-pitch propellers, none of this feathering talk applies.  Be prepared for the unexpected emission of foul language during engine-out procedures, though!&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Approach/Landing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An engine failure during the early phases of approach is generally unproblematic -- it's similar to a failure at cruise, just minus the driftdown.  However, an engine failure on short final can be troublesome due to the high workload of an approach, combined with the thrust asymmetry induced during a full-power, single-engine go-around.  Prompt rudder inputs are essential in order to maintain aircraft track and control during such a maneuver, and engine failure checklists are best deferred until stable flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine failures during the landing roll are rare, by the way, and typically a non-event.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Worse than Engine Failure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are engine damage scenarios that represent a greater hazard to the aircraft than a simple engine failure, or even a fire in an airliner engine.  These fall into three categories: uncontained turbine engine failures, engine detachments, and propeller failures.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Uncontained Turbine Engine Failure&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Turbine engine failures are divided into two types: &quot;contained&quot; failures where the busted parts fly out the tailpipe, and &quot;uncontained&quot; failures where a turbine or compressor disk basically explodes radially, sending parts flying in a 360&amp;deg; radius around the engine; at this point, further damage is a game of aerial roulette, and can range from a few holes in the cowl to near-catastrophic levels of damage that pose a threat to the entire aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Engine Detachment&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Engines, even when pod-mounted, rarely fall off airplanes, and much of the time when they do, they depart quietly, a yanked-back thrust lever and nil engine readings the only signs of their absence visible to the flight crew.  However, a detached engine is somewhat unpredictable in its behavior, and can strike another engine on the same wing or another part of the aircraft, leading to further damage that can compromise aircraft systems or impair the operation of that neighboring engine to the point where the thrust asymmetry becomes uncontrollable.  Nacelle-mounted engines are actually &lt;em&gt;worse&lt;/em&gt; in this regard -- a nacelle-mounted engine departing its nacelle leaves behind a big, draggy air scoop that will severely hamper single-engine flying, and on a light twin, this is simply insult atop injury as you have gone from &quot;barely making it to your site of choice&quot; to &quot;we need to pick the nearest open spot NOW because we're trying to fall out of the sky in a hurry&quot;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Propeller failure&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Propellers do not fail nearly as often as engines do, but when a propeller fails in flight, the results can be catastrophic; an overspeeding prop can fly apart violently or rip its mated engine apart while producing asymmetric forces that have the potential to overwhelm all flight control, while the inability to feather a failed engine's propeller turns it into a drag brake on that side of the aircraft, crippling any attempt to obtain reasonable single-engine climb performance.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-03-20T03:36:50.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12264" PostTypeId="1" AcceptedAnswerId="12273" CreationDate="2015-01-31T07:03:24.780" Score="1" ViewCount="351" Body="&lt;p&gt;We want use RC UAV to take some pictures of  heritage forts (Gadh) around Pune. Do I need a special permission for that ? I have seen some one doing it before but just for to be sure I need to know. is there any official government website that can guide us ? I am so concerned because I want to do a research project. &lt;/p&gt;&#xA;" OwnerUserId="7092" LastEditorUserId="19" LastEditDate="2015-01-31T11:33:30.783" LastActivityDate="2015-01-31T14:21:49.940" Title="Rules and restriction for toy UAV in India on very low heights ? (max 50 meter from ground )" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;regulations&gt;&lt;dgca-india-regulations&gt;&lt;dgca-india&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-02-08T06:48:46.333" ContentLicense="CC BY-SA 3.0" />
  <row Id="12266" PostTypeId="2" ParentId="12242" CreationDate="2015-01-31T08:02:27.507" Score="5" Body="&lt;p&gt;This is a physics question, not an aviation question, and might better be posed on Physics StackExchange.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simply put, the question has an infinite number of answers!  Let me explain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are stationary in a helicopter, waiting to take off, with reference to an observer also standing next to the helicopter, your speed is 0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But with reference to an observer in a static point in space whose frame of reference is the centre of the earth, you are already moving at about 1040MPH.  The surface of the earth is also moving at 1040MPH. (BTW, it is itself impossible to define a static point in space since all of space is moving.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The atmosphere you are about to fly in (assuming zero wind) is also moving at the same speed.  If its speed was zero, with reference to the stationary observer in space, then the 1040MPH wind might make flying a little difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You lift into the hover.  Now to both observers, you are still doing the same speed because speed is a scalar and you have added no force to change your horizontal speed. To the observer standing near the helicopter, the earth, the helicopter and the air it is flying in are all moving at 0 speed.  To the observer in space, they are all moving at 1040MPH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You now fly West at 100MPH.  To the observer standing on the earth, your speed is now 100MPH but to the observer in space, your speed is now 940MPH.  You have slowed down!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By picking any arbitrary observer, at any point in space, and doing any speed you choose, you can see that there are an infinite number of answers to the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only by asking the question with reference to a specific observer, can you answer the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ignore wind and side effects such as the Coriolis effect, the earths rotation has no effect on your journey time since you and the craft you are in must move at the same speed within the same frame of reference, relative to any given observer, together.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-02-01T16:45:02.390" LastActivityDate="2015-02-01T16:45:02.390" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12267" PostTypeId="1" AcceptedAnswerId="12268" CreationDate="2015-01-31T10:22:31.360" Score="4" ViewCount="987" Body="&lt;p&gt;As I understand from the answer to this &lt;a href=&quot;https://aviation.stackexchange.com/questions/8380/how-does-the-hinge-mechanism-of-plug-type-pressure-doors-work&quot;&gt;questions&lt;/a&gt;, plug doors are larger than the hole they mus fit in so that they are plugged thanks to air pressure, leading to several advantages. Then, I found this &lt;a href=&quot;http://www.youtube.com/watch?v=dykoPn5tgEU&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; of a type-C door operating. This door does not seems larger then the hole it must fit in and that confuses me.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this a plug-door? &lt;/li&gt;&#xA;&lt;li&gt;Is there something I miss? &lt;/li&gt;&#xA;&lt;li&gt;Is there other types of door that are not plug-door, or that are plug-door but don't look like plug-door?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-01-31T11:28:33.710" Title="Are type-C doors plug doors?" Tags="&lt;aircraft-design&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12268" PostTypeId="2" ParentId="12267" CreationDate="2015-01-31T11:28:33.710" Score="3" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;, they are not. Most (not sure if all) Airbus door are &lt;strong&gt;not&lt;/strong&gt; plug-type. And neither are &lt;em&gt;cargo&lt;/em&gt; door on most Boeing types.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-01-31T11:28:33.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12269" PostTypeId="2" ParentId="11906" CreationDate="2015-01-31T11:32:52.013" Score="2" Body="&lt;p&gt;The evil mark you are talking about varies. There ara all kinds of PT6, ranging from around 500SHP to 1700SHP, each of them with different limits, including ITT limits. Which PT6 are you talking about? Overtemperature during start means that something is wrong with the engine. Either the starter did not crank the engine fast enough, the engine hot section is worn out or something is wrong with bleed valves/FCU. &lt;/p&gt;&#xA;" OwnerUserId="7070" LastActivityDate="2015-01-31T11:32:52.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12270" PostTypeId="2" ParentId="12205" CreationDate="2015-01-31T11:33:23.520" Score="1" Body="&lt;p&gt;For me, it's simply common sense. It's like with driving a car: I have been driving  for 13 years now and still drive as carefully as I did when I started. I have had one accident in that time; the other car and I skidded on a smooth road. But, we were both driving carefully (roughly 30kmh/20mph in a 80kmh/50mph zone) so nothing more than car body damage happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot always prevent accidents by being careful but you can always attenuate the consequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't want to die nor do I want my guests to die from my negligence, so I am not negligent, be it with the car, the plane (for which I have not long had my licence) or even simply with the windows of my apartment on the 4th floor; negligence kills.&lt;/p&gt;&#xA;" OwnerUserId="3916" LastEditorUserId="2032" LastEditDate="2015-02-01T08:06:43.443" LastActivityDate="2015-02-01T08:06:43.443" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12271" PostTypeId="2" ParentId="12173" CreationDate="2015-01-31T13:46:26.177" Score="2" Body="&lt;p&gt;For landing and take off, lights are essential.  It's possible to do both with just runway lights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the air, VFR pilots can still see ground lights and objects in the sky that are lit (other planes).  This allows them to see the horizon and keep the plane properly oriented.  Navigation is the same as it is during the daytime, with the only exception being that pilotage (flying by reference to objects on the ground) is limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a full moon or nearly full moon and cloudless sky, flying at night is only marginally more difficult than flying during the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a moonless night, or overcast, things are much more difficult.  Flying in an area where the horizon can't be discerned is particularly dangerous and should be avoided.  For those situations, flying IFR is the only safe alternative.&lt;/p&gt;&#xA;" OwnerUserId="7096" LastEditorUserId="3386" LastEditDate="2015-01-31T14:16:27.947" LastActivityDate="2015-01-31T14:16:27.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12273" PostTypeId="2" ParentId="12264" CreationDate="2015-01-31T14:21:49.940" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;A public notice issued by the DGCA in October reads: “DGCA is in the process of formulating the regulations [and globally harmonise those] for certification &amp;amp; operation for use of Unmanned aircraft systems [UAS] in the Indian Civil Airspace. Till such regulations are issued, no non-government agency, organisation, or an individual will launch a UAS in Indian Civil Airspace for any purpose whatsoever.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“There are no regulatory guidelines concerning the sales and operation of such aircraft. So when a request is made for the use of drones we allow it on a ‘case-by-case’ basis. If we feel that they would not pose any security threat or cause any traffic snarls, we allow the request,” explained another senior police officer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.thehindu.com/news/national/drones-fly-in-mumbai-despite-dgca-ban/article6720004.ece&quot; rel=&quot;nofollow&quot;&gt;The Hindu, December 24 2014&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-01-31T14:21:49.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12274" PostTypeId="2" ParentId="12262" CreationDate="2015-01-31T15:03:51.960" Score="18" Body="&lt;p&gt;The Class C &lt;em&gt;outer area&lt;/em&gt; is the airspace surrounding Class C airspace out to 20nm, and from the lower limit of radar coverage to the top of the controller's airspace.  The outer area is not charted, although you can see in the white boxes (in the chart below) adjacent to Class C airports that you can initiate communication within 20nm.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YhwPf.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;ATC offers Class C services (e.g., flight following) on a workload-permitting basis to participating aircraft operating in the outer area, and aircraft in 2-way radio communication will receive IFR/VFR aircraft separation services.&lt;/p&gt;&#xA;&lt;p&gt;So you can think of Class C airspace as 3 concentric rings: the 20nm outer area, the 10nm shelf area, and the 5nm surface area.&lt;/p&gt;&#xA;&lt;p&gt;Source &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap3_section_2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 3-2-4&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="14897" LastEditDate="2021-04-13T00:46:17.577" LastActivityDate="2021-04-13T00:46:17.577" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="12275" PostTypeId="2" ParentId="12260" CreationDate="2015-01-31T15:16:21.087" Score="14" Body="&lt;p&gt;You're confusing the airspace &lt;em&gt;height&lt;/em&gt; with airspace &lt;em&gt;altitude&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html&quot; rel=&quot;noreferrer&quot;&gt;definition of Class C&lt;/a&gt; (in the US) is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3-2-4 (a) Generally, that airspace from the surface to 4,000 feet&#xA;  above the airport elevation (charted in MSL)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you look at chart for the Class C for Colorado Springs (elevation 6,187), the surface area of the airspace goes up to 10,200 ft MSL, approximately 4,000ft above the airport elevation of 6187.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VaOd4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-04-28T14:04:06.180" LastActivityDate="2016-04-28T14:04:06.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12277" PostTypeId="1" AcceptedAnswerId="12307" CreationDate="2015-01-31T21:13:11.723" Score="16" ViewCount="8679" Body="&lt;p&gt;Why are &lt;a href=&quot;http://en.wikipedia.org/wiki/Geodetic_airframe&quot; rel=&quot;noreferrer&quot;&gt;geodesic airframes&lt;/a&gt; no longer produced?  Do they cost more than conventional structures?  Are they not as strong as conventional structures?  I assume it is insufficient cost benefit ratio, but how does that work out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/File:Wellingtons_under_construction_WWII_IWM_CH_5980.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DHGjA.jpg&quot; alt=&quot;Vickers Wellington bombers under construction.&quot;&gt;  &lt;sup&gt;Wellingtons under construction. Photo: Royal Air Force&lt;/sup&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="1961" LastEditDate="2015-02-02T22:13:30.883" LastActivityDate="2021-02-14T18:01:06.237" Title="Why are geodesic airframes no longer produced?" Tags="&lt;aircraft-design&gt;&lt;airframe&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12278" PostTypeId="2" ParentId="5032" CreationDate="2015-01-31T23:41:12.563" Score="1" Body="&lt;p&gt;The Air Traffic Basics course is the first information new FAA controllers are exposed to, and it is &lt;a href=&quot;http://atbasics.faa.gov/public_index&quot; rel=&quot;nofollow&quot;&gt;available to the public&lt;/a&gt;. This is a comprehensive introduction to background aviation knowledge from a controller's perspective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that and getting into phraseology, there is &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA JO 7110.65&lt;/a&gt;. This document is THE standard for U.S. air traffic control procedures. Everything controllers say comes from that book.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-12-01T00:59:45.073" LastActivityDate="2015-12-01T00:59:45.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12279" PostTypeId="1" CreationDate="2015-01-31T23:41:13.440" Score="4" ViewCount="348" Body="&lt;p&gt;I was looking at the RNAV (GPS) approach to runway 10 at Kimball, NE (KIBM):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4DnyG.png&quot; alt=&quot;RNAV (GPS) RWY 10 KIBM&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and was left wondering &quot;How on earth could the straight-in visibility minima for approach categories C and D be &lt;em&gt;lower&lt;/em&gt; than for approach categories A and B?&quot;  Is this merely a charting error, or is there some strange clause in the TERPS that I'm not aware of that makes this possible?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-02-08T19:26:59.283" Title="KIBM RNAV (GPS) 10 -- did I find a charting error, or what is the TERPS rationale for this?" Tags="&lt;aeronautical-charts&gt;&lt;gnss&gt;&lt;instrument-procedures&gt;&lt;non-precision-approach&gt;&lt;terps&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12282" PostTypeId="1" CreationDate="2015-02-01T01:00:57.983" Score="7" ViewCount="3892" Body="&lt;p&gt;Why don't airliners have a navigation GPS as &quot;back up&quot; in case of a pitot tube malfunction? Aeropero 603 and Air France 447 plus many other im sure, could have been saved if these aircrafts would have had a simple Navigation GPS as a plan B. The GPS could have given the pilot the basic information needed to keep flying instead of leaving them confused about what the instruments were showing due to the blocked pitot tubes. having reliable information of ground speed, heading and altitude would have helped the pilots recognize the situation they were in, which was caused by Pitot tubes blockage. Most private pilots now use GPS why not the big airliners?&#xA;There is many blogs about why airliners do not have GPS tracking so the planes could be found after a crash, but none talking about why GPS is not use to help prevent some of those crashes.&lt;/p&gt;&#xA;" OwnerUserId="7103" LastActivityDate="2015-02-02T04:33:50.853" Title="Why don't airliners have a navigation GPS as back up in case of a pitot tube malfunction?" Tags="&lt;navigation&gt;&lt;gnss&gt;&lt;pitot-static&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ClosedDate="2015-02-02T02:31:11.707" ContentLicense="CC BY-SA 3.0" />
  <row Id="12283" PostTypeId="1" AcceptedAnswerId="12286" CreationDate="2015-02-01T01:04:53.730" Score="4" ViewCount="8684" Body="&lt;p&gt;How long does it typically take Boeing to make a new plane model (e.g the 787), from the moment they decide to make a plane (the moment they decide to create a new 7X7) to the moment the first plane (in this case the first 787) flies commercially?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="97" LastEditDate="2015-02-04T03:12:38.407" LastActivityDate="2015-02-04T03:12:38.407" Title="How long does it take Boeing to develop an aircraft?" Tags="&lt;aircraft-design&gt;&lt;boeing&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12284" PostTypeId="2" ParentId="12282" CreationDate="2015-02-01T01:22:24.523" Score="21" Body="&lt;p&gt;Airliners do generally have GPS receivers, but GPS doesn't give you the information that's needed in this case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In AF 447, the primary consequence of the blocked pitot tubes was that the &lt;em&gt;flight envelope protection system&lt;/em&gt; couldn't do its job properly and therefore automatically disengaged together with the autopilot. The subsequent crash was caused by the pilots' confusion and failure to realize which consequences this had for the aircraft's reaction to their control inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what this system needs to function is &lt;em&gt;not&lt;/em&gt; something a GPS system can possibly provide. GPS knows how fast the aircraft is moving &lt;em&gt;relative to the earth&lt;/em&gt;, but for flight envelope protection you need to know how fast the aircraft is moving &lt;em&gt;relative to the surrounding air&lt;/em&gt;, which GPS doesn't have any way of knowing. The differences between these values is caused by wind and can be pretty large. It would be a recipe for disaster to let the computer limit what the pilot can do based on an arbitrary assumption that there's no wind. (And, as Terry comments, there's an additional difference caused by air pressure).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I remember correctly, the AF 447 investigation concluded that the pitot tubes had thawed and began functioning properly well before impact; it was &lt;em&gt;not&lt;/em&gt; the loss of airspeed indication that prevented the pilots from salvaging the situation. By this time the pilots were confused and &lt;em&gt;thought&lt;/em&gt; the airspeed indication was still malfunctioning because it showed a much slower speed than they thought they ought to have -- whereas in fact it was working perfectly well.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-02-01T01:22:24.523" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12285" PostTypeId="1" AcceptedAnswerId="12294" CreationDate="2015-02-01T03:48:41.337" Score="7" ViewCount="623" Body="&lt;p&gt;Just how often do airline pilots practice V1 cuts when in the sim? Is it the kind of thing that turns up practically every sim session, or is it something that's much more sporadic?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-02-01T14:18:37.820" Title="How often do V1 cuts come up in airline sim training?" Tags="&lt;flight-training&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12286" PostTypeId="2" ParentId="12283" CreationDate="2015-02-01T04:07:01.360" Score="7" Body="&lt;p&gt;For the general question, the answer will be &quot;it depends on the aircraft.&quot; Specifically for the 787, though, the '7E7' program was officially announced on &lt;a href=&quot;http://seattletimes.com/html/nationworld/2009373399_apusboeing787historyglance.html&quot; rel=&quot;nofollow&quot;&gt;January 29, 2003&lt;/a&gt;. The program was later renamed to 787. It received its type certificate on &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=13064&quot; rel=&quot;nofollow&quot;&gt;August 26, 2011&lt;/a&gt; and flew its first passenger revenue flight on &lt;a href=&quot;http://www.reuters.com/article/2011/10/26/us-dreamliner-idUSTRE79P02Q20111026&quot; rel=&quot;nofollow&quot;&gt;October 26, 2011&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, from the time the program began to the time of the first revenue flight was about &lt;strong&gt;8 years and 9 months&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this is not including the R&amp;amp;D time invested on different projects whose R&amp;amp;D ended up being used either partially or completely in the 787 design before the 787 program itself began.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be noted that not every airframe they start developing ever actually flies. Notably, Boeing worked on designs including &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747#747-500X.2C_.E2.88.92600X.2C_and_.E2.88.92700X&quot; rel=&quot;nofollow&quot;&gt;larger 747 variants&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_Sonic_Cruiser&quot; rel=&quot;nofollow&quot;&gt;Sonic Cruiser&lt;/a&gt; (which would have cruised at Mach 0.98) before beginning the 7E7 program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to completely new airframes, aircraft manufacturers also commonly make derivative airframes based on existing product families. Current examples of derivatives in development include the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737_MAX&quot; rel=&quot;nofollow&quot;&gt;737MAX&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow&quot;&gt;A320neo&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777X&quot; rel=&quot;nofollow&quot;&gt;777X&lt;/a&gt;, and &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A330neo&quot; rel=&quot;nofollow&quot;&gt;A330neo&lt;/a&gt; (&quot;neo&quot; stands for &quot;new engine option.&quot;) However, development time on derivatives can vary widely depending on how much modification is being made to the existing airframes and the level of resources being devoted to the project (which depends on market pressure.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a past example, the 2nd-generation Boeing 777 aircraft were announced on &lt;a href=&quot;http://www.deseretnews.com/article/746327/Boeing-launches-stretch-777-jetliner.html&quot; rel=&quot;nofollow&quot;&gt;February 29, 2000&lt;/a&gt; with the first aircraft, the 777-300ER, being certificated on &lt;a href=&quot;http://www.boeing.com/boeing/commercial/777family/background.page&quot; rel=&quot;nofollow&quot;&gt;March 16, 2004&lt;/a&gt;, and first service entry on &lt;a href=&quot;http://www.boeing.com/boeing/commercial/777family/background.page&quot; rel=&quot;nofollow&quot;&gt;May 10, 2004&lt;/a&gt;. This gives a time of about &lt;strong&gt;4 years and 2 months&lt;/strong&gt; from announcement to first service entry. This was likely slowed by the sharp downturn in aircraft orders following the 1999-2000 &quot;.com bust&quot; and, especially, the September 11, 2001 terrorist attacks in the U.S.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also important is the FAA rule for applying for a type certificate. This will apply for new programs like the 787, but not for derivative programs like the 777X, which amend the original type certificate and do not need a new one. In &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.21_117&quot; rel=&quot;nofollow&quot;&gt;14 CFR §21.17&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An application for type certification of a transport category aircraft is effective for &lt;strong&gt;5 years&lt;/strong&gt; and an application for any other type certificate is effective for &lt;strong&gt;3 years&lt;/strong&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So once Boeing applies for a new type certificate, they have 5 years to get the type cetificate approved, unless they convince the FAA upfront that more time is needed. If the time runs out they must reapply, and the new type certificate would require the aircraft to comply with all new regulations passed since their original application.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="1696" LastEditDate="2015-02-02T23:31:56.917" LastActivityDate="2015-02-02T23:31:56.917" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12287" PostTypeId="2" ParentId="12205" CreationDate="2015-02-01T04:16:20.680" Score="8" Body="&lt;p&gt;In short, &lt;em&gt;discipline.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my case, I learned the discipline to use a checklist for every action on every flight the one time I decided not to use a checklist while taxiing from the fuel pump back to the parking ramp. It was winter, and a snowplow pulled up behind me, so I decided not to use the checklist in the interest of expediency (ha!). I primed the engine, checked the fuel valve, engaged the electrical system, keyed the starter, and the engine responded by firing up and then immediately dieing. Repeat about a half-dozen times, at which point, I finally decided to use the checklist because something obviously wasn't right. Once again, primed the engine, checked the fuel valve, move the mixture to the rich posi--&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oh...I had left the mixture in the idle-cut-off position. Oops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've used a checklist religiously ever since then ;)&lt;/p&gt;&#xA;" OwnerUserId="4159" LastEditorUserId="65" LastEditDate="2015-03-09T20:06:05.140" LastActivityDate="2015-03-09T20:06:05.140" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12288" PostTypeId="2" ParentId="3679" CreationDate="2015-02-01T04:20:04.350" Score="5" Body="&lt;p&gt;In light general aviation aircraft, you lower the gear when abeam the touchdown point on downwind, then double-check that the gear is down on final (and possibly on base, as well).&lt;/p&gt;&#xA;" OwnerUserId="4159" LastActivityDate="2015-02-01T04:20:04.350" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12289" PostTypeId="2" ParentId="12282" CreationDate="2015-02-01T05:43:39.437" Score="4" Body="&lt;p&gt;The short answer to this question is that commercial airliners &lt;strong&gt;do have GPS&lt;/strong&gt; and they have for a long time. AF447 almost certainly would have been equipped with GPS. While what Terry said about the difference between airspeed and ground speed is very true, AF447 could have seen from their GPS unit that they were moving much slower than what they should have been.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, judging from the cockpit voice recorder transcripts, it seems that they were panicking and failing to think logically or communicate well with each other. It was almost entirely a case of pilot error, not lack of accurate information. The pilot in the right seat was almost continually pulling back on his side stick. This caused the aircraft to climb and bleed off airspeed until the wings stalled. Even after the aircraft entered a stall condition, the pilots never lowered the nose, which would have recovered from the stall. Instead, the pilot in the right seat actively held the nose high for the entire descent to the ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the pitot tubes thawed several minutes before the actual crash. All of the instrument indications were correct for quite a long time before the aircraft hit the ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information on AF447, see &lt;a href=&quot;http://www.popularmechanics.com/technology/aviation/crashes/what-really-happened-aboard-air-france-447-6611877&quot; rel=&quot;nofollow&quot;&gt;Popular Mechanics' annotated cockpit voice recorder transcript&lt;/a&gt; of the incident.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-02-01T05:43:39.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12291" PostTypeId="2" ParentId="8939" CreationDate="2015-02-01T10:45:01.667" Score="-3" Body="&lt;p&gt;The problem is... if you are asked/told to turn it off, whether it's an airband radio or a passive device then you HAVE to turn it off. Cabin crew don't want you listening to the pilot's radio traffic particularly if any kind of emergency arises or flight detour. Think about it!&lt;/p&gt;&#xA;" OwnerUserId="7106" LastActivityDate="2015-02-01T10:45:01.667" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12292" PostTypeId="2" ParentId="12279" CreationDate="2015-02-01T13:47:57.320" Score="0" Body="&lt;p&gt;As UFO suggested in the comments above, the values come from the Tables in TERPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason why the visibility is &lt;em&gt;greater&lt;/em&gt; for Category A and B is because in the typical &quot;dive and drive&quot; non-precision approach, the slower aircraft would descend to the MDA beyond 10,000ft from the &lt;em&gt;landing threshold point&lt;/em&gt;, and therefore before the &lt;em&gt;visual area&lt;/em&gt; of the approach. (&lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentid/11698&quot; rel=&quot;nofollow&quot;&gt;TERPS Section 3.3.2&lt;/a&gt;)  Increasing the visibility requirement would allow the slower aircraft to see the airport environment from further away.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-01T13:53:43.627" LastActivityDate="2015-02-01T13:53:43.627" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12293" PostTypeId="2" ParentId="12277" CreationDate="2015-02-01T14:12:41.917" Score="10" Body="&lt;p&gt;The switch from internal frames to structural skin airframes -- called &lt;em&gt;monocoque&lt;/em&gt; construction -- is fairly well covered in &lt;a href=&quot;http://en.wikipedia.org/wiki/Monocoque&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Early aircraft were constructed using internal frames, typically of&#xA;  wood or steel tubing, which were then covered (or skinned) with&#xA;  fabric&lt;a href=&quot;http://www.cubcrafters.com/carboncubss&quot; rel=&quot;noreferrer&quot;&gt;3&lt;/a&gt; such as irish linen or cotton. The skin added nothing to&#xA;  the structural strength of the airframe and was essentially dead&#xA;  weight beyond providing a smooth sealed surface. &lt;strong&gt;By thinking of the&#xA;  airframe as a whole, and not just the sum of its parts, it made sense&#xA;  to adopt a monocoque structure&lt;/strong&gt; and it did not take long for various&#xA;  companies to adopt practices from the boat industry such as laminating&#xA;  thin strips of wood&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, we are still producing tube and fabric airplanes, particularly taildraggers based on classic designs, such as this &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Champion_Citabria&quot; rel=&quot;noreferrer&quot;&gt;American Champion Citabria&lt;/a&gt; and this &lt;a href=&quot;http://www.cubcrafters.com/carboncubss&quot; rel=&quot;noreferrer&quot;&gt;Super Cub&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WrKeJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/foRP3.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-01T15:09:36.957" LastActivityDate="2015-02-01T15:09:36.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12294" PostTypeId="2" ParentId="12285" CreationDate="2015-02-01T14:15:14.960" Score="8" Body="&lt;p&gt;During initial and upgrade training you will fly many V1 cuts. At every recurrent check ride you'll experience V1 cuts both as pilot flying and non flying pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In our sim events the V1 cut would generally be a 600 RVR takeoff with 10 kt direct crosswind from the side that would fail. Not always though -- you expected the V1 cut on every takeoff. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-02-01T14:15:14.960" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12295" PostTypeId="2" ParentId="12285" CreationDate="2015-02-01T14:18:37.820" Score="2" Body="&lt;p&gt;Sims are useful for three different groups of tasks that are difficult or a waste of time to do in the airplane:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Instrument approaches and departures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Normal Procedures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Emergency Procedures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;V1 cuts come in the last category, and you will get plenty of them since you don't want to be doing them on the actual runway. You need to develop the proper intellectual acumen and muscle memory to react to the event so that you can handle one safely when it happens in real life.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-02-01T14:18:37.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12296" PostTypeId="1" AcceptedAnswerId="12299" CreationDate="2015-02-01T17:41:41.910" Score="3" ViewCount="1028" Body="&lt;p&gt;This recent aviation.SE question asks &lt;a href=&quot;https://aviation.stackexchange.com/questions/12282/why-dont-airliners-have-a-navigation-gps-as-back-up-in-case-of-a-pitot-tube-mal&quot;&gt;why isn't GPS used as a backup speed indicator&lt;/a&gt;. The answers given mention that GPS cannot indicate &lt;em&gt;airspeed&lt;/em&gt;. However, there are other methods to indicate airspeed. At the very least, a small &lt;a href=&quot;http://en.wikipedia.org/wiki/Anemometer&quot; rel=&quot;nofollow noreferrer&quot;&gt;anemometer&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Weather_vane&quot; rel=&quot;nofollow noreferrer&quot;&gt;vane&lt;/a&gt; might be deployed in a fashion similar to how a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;ram air turbine&lt;/a&gt; is deployed. Or at the very least, deploy the ram air turbine and measure the RPM or voltage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another creative method might be to release a small red sponge ball, and have a camera/sensor mounted in the top of the tail (where the A380 already has a camera) determine the vector that it flys away. Image processing for this type of work has been available for years already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, these solutions would only be deployed when necessary. I wager that using the ram air turbine to determine the airspeed could be done in software with no added weight or mechanical components added to the vehicle. Assuming that the vehicle already has a camera in the tail (such as the A380), adding the ability to deploy a small sponge ball would be less of a retrofit than adding &lt;a href=&quot;https://aviation.stackexchange.com/questions/2229/how-do-airliners-facilitate-in-flight-calls-for-mobile-phones/2239#2239&quot;&gt;cellular telephone service&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-02-03T01:55:21.377" Title="Backup airspeed indicators (lack thereof)" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;" AnswerCount="3" CommentCount="12" ClosedDate="2015-02-05T15:31:22.530" ContentLicense="CC BY-SA 3.0" />
  <row Id="12297" PostTypeId="2" ParentId="12282" CreationDate="2015-02-01T18:49:40.047" Score="1" Body="&lt;p&gt;Airliners do have GPS units. As the other answers and comments have indicated, GPS does not provide airspeed (or angle of attack) information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would seem reasonable to use the GPS as a backup in the following way: Under normal operation, the difference between TAS and the GPS estimate (allowing for some computational latency) should be fairly constant (the difference being the wind speed). When the difference exceeds some noise threshold for a period of time it issues a warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This wouldn't help in the case of Aeropero 603 but may have helped in the Air France 447 incident. (To clarify what I mean by help, I mean to reduce cockpit confusion.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the former case, a similar tracking system between the radar altimeter and the&#xA;barometric altimeter may have helped.&lt;/p&gt;&#xA;" OwnerUserId="3212" LastEditorUserId="3212" LastEditDate="2015-02-02T04:33:50.853" LastActivityDate="2015-02-02T04:33:50.853" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="12298" PostTypeId="2" ParentId="12296" CreationDate="2015-02-01T19:28:24.263" Score="5" Body="&lt;h1&gt;Possible approaches for a backup Airspeed Indicator&lt;/h1&gt;&#xA;&#xA;&lt;h3&gt;Why not use GPS?&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does not indicate &lt;em&gt;airspeed&lt;/em&gt;, only ground speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Why not use the RAT?&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The RAT will rotate at different speeds for the same airspeed and different altitudes and on different days. (Simon)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Why not use a coloured ball?&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The ball would be straight back during cruise unless weighted down significantly. (ratchet freak)&lt;/li&gt;&#xA;&lt;li&gt;The speed of the ball would help determine airspeed. For a second or two. Now what? And there is a much simpler method. If you are flying safely, and you lose airspeed indication, leave the pitch and power where they are, and you will continue to fly safely. (Simon)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Why use anything at all?&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;We already have backup procedures for a broken ASI, which is to fly pitch and power. the problem is not the lack of a airspeed reading, but poor airmanship. (rbp)&lt;/li&gt;&#xA;&lt;li&gt;If the plane was flying safely before the ASI failed, why cannot it continue to do so? Same pitch and power = same airspeed. I am of course assuming cruise, otherwise, this and your methods all fail. (Simon)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Other approaches:&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some experimental aircraft use &lt;a href=&quot;http://www.eaa.ca/experimenter/articles/2009-06_zodiac.asp&quot;&gt;a venturi &lt;/a&gt; to measure airspeed. (rbp)&lt;/li&gt;&#xA;&lt;li&gt;The Tiger Moth has a hinged plate on the wing struts that rotates as the air pushes against it, and you can read that angle against a track marked in mph. (Dan Hulme)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="354" LastActivityDate="2015-02-01T19:28:24.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12299" PostTypeId="2" ParentId="12296" CreationDate="2015-02-01T21:12:53.590" Score="6" Body="&lt;p&gt;In order to answer your question first we need to figure out what we're trying to accomplish with airspeed. For the most part the goal is &quot;envelope protection&quot; - keeping the pilots from either stalling the aircraft or overspeeding (and overstressing) it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the first thing to know is thaton modern transport category aircraft there are already backup systems to compensate for a failed airspeed indicator.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For starters there are usually at TWO (visible) airspeed indicators (one for each flight control station - pilot &amp;amp; co-pilot). The airspeed indicators are usually using two different pitot (ram air pressure) sources, so that if one pitot system or indicator fails the aircraft can still be flown on the others.&lt;br&gt;&#xA;In addition to those two indicators there is often a third &quot;tie-breaker&quot; system on modern aircraft which is used to determine which system has failed (if two systems agree the third is declared insane and ignored).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the unlikely event that all of the pitot-based airspeed indicators fail they aren't the only system providing envelope protection: Angle-of-Attack vanes are used to determine when the wing is approaching the critical angle of attack (and is in danger of stalling). These operate independently of the pitot system as a redundant form of stall protection, and as with the pitot system aircraft usually have more than one AoA vane installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the pitot-based airspeed indicators and the AoA vanes are critical systems, and are heated (to prevent ice from accumulating and interfering with their proper operation) and monitored (by onboard computers and/or the pilots).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally in the face of a failure of all of those systems there is the ultimate fallback method that others have described: &lt;code&gt;Pitch + Power = Performance&lt;/code&gt;.&lt;br&gt;&#xA;A pilot should be able to at the very least maintain level flight, descend, climb, and make standard-rate turns within a safe flight envelope by reference to engine power and aircraft attitude.&lt;br&gt;&#xA;While that's far from an ideal situation it is one pilots are trained for.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-01T21:12:53.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12300" PostTypeId="1" AcceptedAnswerId="12305" CreationDate="2015-02-01T21:32:16.743" Score="39" ViewCount="10196" Body="&lt;p&gt;Apparently, the time for boarding and deboarding an airplane is a large cost factor and something airlines try to minimize but have trouble controlling because the passengers do it themselves.&#xA;A solution would be to have passengers board a passenger cabin outside of the airplane and then slide that cabin into the plane via a nose-hatch, much like large volume freight. Has this been considered? If yes, why was it not pursued?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="15311" LastEditDate="2017-12-10T15:42:39.653" LastActivityDate="2017-12-10T15:42:39.653" Title="Why don't airlines load their passengers like freight?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;passenger&gt;&lt;economics&gt;&lt;boarding&gt;" AnswerCount="8" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12301" PostTypeId="2" ParentId="12300" CreationDate="2015-02-01T22:09:27.417" Score="7" Body="&lt;p&gt;The first and biggest concern would be the weight of the container. They need to have walls, floor and a ceiling and be able to lock in place on the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also each division between containers would remove some room available for another row of seats in the traditional method.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-01T22:09:27.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12302" PostTypeId="2" ParentId="12296" CreationDate="2015-02-01T22:17:12.510" Score="6" Body="&lt;p&gt;To expand on voretaq7's answer -- airspeed is measured by aircraft and used by pilots as a proxy for Angle of Attack because early aircraft designers found it easier to measure airspeed (using pitot and static pressures in a calibrated differential pressure gauge aka airspeed indicator) than they did measuring the Angle of Attack (alpha) of the wing directly (this requires an AoA vane with its associated electrical transducer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Navy has a long-standing practice of fitting AoA gauges into the cockpit of its aircraft, and naval aviators are trained to use the AoA gauge as a primary flight instrument; however, civil aviation retains the legacy of airspeed as a proxy for AoA, despite the near-universal fitment of AoA vanes to transport class aircraft to provide stall warnings.  This has started to change, though: Boeing glass cockpits with &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html&quot; rel=&quot;nofollow&quot;&gt;recent firmware&lt;/a&gt; provide a mini-AoA gauge as an option.  While it's not accurate enough (primarily due to annoying Mach effects) to be used as a primary flight instrument in the style a naval aviator uses their Hornet's AoA gauge when landing on a carrier deck, it's still useful as a backup/crosscheck for airspeed trends (if your ASI is showing 50 knots with the AoA indicator reading low, you have a broken ASI, not a stall).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-02-03T01:55:21.377" LastActivityDate="2015-02-03T01:55:21.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12303" PostTypeId="1" CreationDate="2015-02-01T22:21:04.243" Score="4" ViewCount="2202" Body="&lt;p&gt;I'm assuming that almost everyone on this website has seen the movie Airplane at least a few times...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last time I was watching it I was wondering how plausible the actual act of having a single engine prop pilot, with a lot of training (maybe comparable to a modern day aerobatic pilot), land a quad engine passenger jet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/76dm0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2016-04-27T08:34:31.997" Title="Could a single engine pilot land a passenger jet? (from Airplane)" Tags="&lt;landing&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12304" PostTypeId="1" AcceptedAnswerId="12339" CreationDate="2015-02-01T23:02:50.163" Score="6" ViewCount="2057" Body="&lt;p&gt;Chuck Aaron is the &lt;a href=&quot;http://www.wired.com/2011/06/red-bull-chuck-aaron/#slideid-121761&quot; rel=&quot;nofollow&quot;&gt;only FAA-qualified aerobatic helicopter pilot&lt;/a&gt; - How'd he do it?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What requirements does one need to meet in order to perform aerobatics in a helicopter?  Specifically, the training/qualifications and FAA paperwork necessary.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Who certifies said pilot, if there is no one certified themselves to do so?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-02-03T04:12:39.317" LastActivityDate="2015-06-22T06:16:02.580" Title="What is required to be an &quot;FAA-qualified helicopter aerobatics pilot&quot;?" Tags="&lt;helicopter&gt;&lt;aerobatics&gt;&lt;faa-approval&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12305" PostTypeId="2" ParentId="12300" CreationDate="2015-02-01T23:26:20.263" Score="41" Body="&lt;p&gt;Boarding takes a long time, true. There are &lt;a href=&quot;http://arxiv.org/pdf/0802.0733.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more efficient strategies (.pdf)&lt;/a&gt; which &lt;a href=&quot;http://arxiv.org/abs/1108.5211&quot; rel=&quot;nofollow noreferrer&quot;&gt;have been proven&lt;/a&gt; to speed up boarding by between 20% and 50%, still they are not adopted. Why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to load the baggage, too. Also the catering. And fuel. You need to inspect the aircraft, run through checklists and brief the new crew. This all takes up time, too. Airlines do not see a big saving by loading passengers faster, and then waiting for all other jobs to be completed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your radical idea of containerizing passenger transport would certainly speed up things, but it would cost a lot of payload.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The most efficient pressure vessel is a sphere, and the next efficient is a cylinder with spherical ends. Pressurizing a boxy container is structurally very inefficient.&lt;/li&gt;&#xA;&lt;li&gt;Loading passengers on palettes first and sliding those palettes through a narrow opening takes time in itself. And the palettes have their own weight, their own floor, their own support structure for the baggage racks, their own cabeling for the entertainment system. They would, however, not need their independent pressurization, so their weight impact would be moderate.&lt;/li&gt;&#xA;&lt;li&gt;A possible &quot;flatbed&quot; airliner which could attain the shortest boarding times has only half as much fuselage height (or less) to transmit bending loads along its length. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9917/why-does-the-757-fuselage-bend-more-on-turbulence-than-those-of-other-airplanes&quot;&gt;See here&lt;/a&gt; for an example of buckling in a fuselage skin due to bending loads. Now consider that reducing height by 50% will need four times more cross section in the longerons to keep stiffness constant. That will make the fuselage much heavier.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In the end, airlines go with the solution which maximizes their profits. By using a hollow cylinder and let their &quot;cargo&quot; self-load, they can maximize their payload and get tolerable boarding times. Tolerable for them, that is. That better loading procedures could allow you to come to the airport later is of no interest to them. If they would see an advantage in shorter boarding times, there would be ample of opportunity by improving strategies, even with existing airplane designs.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-02T16:56:16.053" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="12306" PostTypeId="2" ParentId="12300" CreationDate="2015-02-01T23:45:00.777" Score="17" Body="&lt;p&gt;The system you propose would be extremely heavy compared to existing aircraft. More weight means more fuel and more fuel means even &lt;em&gt;more&lt;/em&gt; fuel to carry that fuel through the air, and even more fuel to carry &lt;em&gt;that&lt;/em&gt; fuel and so on.  Fuel is one of the biggest expenses an airline faces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also be extremely expensive.  To gain any time, you'd have to have the departing passenger capsule loaded and ready before the arriving passengers have left their capsule. That means you need twice as many capsules as planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the time saving wouldn't be all that great.  You'd still have to refuel the plane and load and unload the cargo.  Manoeuvring a fuselage-sized capsule into the plane would be a long job.  I'm far from convinced that it would be faster than getting however many hundred people through the door.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-02-01T23:45:00.777" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12307" PostTypeId="2" ParentId="12277" CreationDate="2015-02-01T23:50:12.970" Score="22" Body="&lt;p&gt;Geodesic (sometimes also spelled geodetic) designs were used in aviation as early as 1909, in the &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Sch%C3%BCtte-Lanz_airships#SL1&quot; rel=&quot;noreferrer&quot;&gt;Schütte-Lanz SL1&lt;/a&gt; airship. It had a wooden structure with fabric covering, and Professor Johann Schütte, the scientific head of this design, used the most efficient method conceivable. However, planning the shape of all structural members was an enormous amount of work, and stretching an existing ship by inserting a new section was almost impossible. For those reasons, the late Schütte-Lanz airships used aluminum frames with conventional design, just like Zeppelin did from the beginning. Diagonal wire bracing was used to take up shear loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F3TPq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Geodesic frames are good in transferring both bending and shear loads. This is helpful when the aerodynamic covering is not stiff enough to contribute any shear stiffness, as in the case of fabric covering. However, when the skin is made from the same material as the frame, it can carry shear loads and a geodesic frame would not improve matters. Now it is better to carry longitudinal loads in longerons and shear in the skin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But geodesic constructions are not dead. &lt;a href=&quot;http://en.wikipedia.org/wiki/Computer-aided_design&quot; rel=&quot;noreferrer&quot;&gt;CAD&lt;/a&gt; makes the design effort manageable, and in some cases they give a weight advantage. Look at the casing of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;noreferrer&quot;&gt;EJ200 engine&lt;/a&gt;: It uses a geodesic reinforcement to make the casing light and strong and to prevent harmful vibrations. In the end, a jet engine casing is a big pressure vessel and needs to be strong, stiff and light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uObN3.jpg&quot; alt=&quot;Eurojet EJ200 for Eurofighter Typhoon&quot;&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Eurojet_EJ200_for_Eurofighter_Typhoon_PAS_2013_01_free.jpg&quot; rel=&quot;noreferrer&quot;&gt;photo by Julian Herzog, CC-BY&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="5665" LastEditDate="2015-11-08T14:00:33.727" LastActivityDate="2015-11-08T14:00:33.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12308" PostTypeId="1" AcceptedAnswerId="12318" CreationDate="2015-02-02T01:47:51.797" Score="13" ViewCount="2553" Body="&lt;p&gt;During a mission, military aircraft often shed a lot of weight from takeoff to landing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An F-15C (empty weight: 28,000 lbs) carries an internal fuel load of 13,455 lbs (almost a third of take-off weight not including pilot and ordnance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cargo plane like the C-17 may perform a combat off-load while airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, the aircraft I worked on in the army were deadlined whenever 1% of total aircraft weight was removed, requiring either the part to be reinstalled or a total reweigh prior to next flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operationally speaking, how are these &quot;fat burning exercises&quot; completed without jeopardizing crew and equipment due to shifting weight and/or CG?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="5517" LastEditDate="2015-02-19T19:34:32.767" LastActivityDate="2016-03-15T21:54:02.500" Title="How does dropping ordnance affect the weight and balance of the aircraft?" Tags="&lt;military&gt;&lt;weight-and-balance&gt;&lt;cargo&gt;&lt;ordnance&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12309" PostTypeId="1" AcceptedAnswerId="12311" CreationDate="2015-02-02T02:25:36.017" Score="36" ViewCount="11422" Body="&lt;p&gt;Related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12300/why-dont-airlines-load-their-passengers-like-freight&quot;&gt;this&lt;/a&gt; question about plane loading efficiency, if planes have multiple entrances (generally 6 or more) why are planes not loaded from both ends? I think I've seen it happen sometimes, but the majority of my flights are on 737s and are just loaded from the front entrance. &lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2017-01-23T21:02:19.493" Title="Why aren't planes loaded from both ends?" Tags="&lt;passenger&gt;&lt;ground-operations&gt;&lt;boarding&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12310" PostTypeId="2" ParentId="12309" CreationDate="2015-02-02T02:44:04.507" Score="13" Body="&lt;p&gt;I'm not sure, but I think this is somewhat a geometry thing. If planes are being loaded from a jetbridge, it would have to get past the wing to reach the rear door. That would involve it having to drive &lt;em&gt;around&lt;/em&gt; the wing to get to the door, which is somewhat space-intensive, and also requires a pretty long jetway with limited ability to have supports along its length (since it has to deal with different wing sizes). On planes with multiple front doors along one side, it's not that uncommon to see them being used, whether they're on different levels or there's just a door at the front and another door in front of the wing. There, it's just a matter of how many jetways the airport has at the gate, but they don't have to drive around the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When planes are being loaded or unloaded away from the airport, it's not uncommon to load/unload from the back as well as the front; there, they just have to use two mobile lounges (at IAD) or airstairs (just about anywhere else).&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-02-02T02:44:04.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12311" PostTypeId="2" ParentId="12309" CreationDate="2015-02-02T03:04:49.750" Score="42" Body="&lt;p&gt;The aviation industry is already running at near-peak efficiency, performing crucial tasks simultaneously to ensure quick turn-around.  Trying to speed up the boarding process by allowing entrance from both ends would be doable with a large amount of changes to the existing process, in both operations and infrastructure.  However, the result would be horrendous and time- and resource-consuming at worst and comical at best.&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Jetways need to be able to reach all points of ingress/egress, where currently, they only reach the forward doors.  Seeing as aircraft nose-in at the gate, to reach the aft doors would require a jetway that goes &lt;em&gt;around&lt;/em&gt; the wing (&lt;em&gt;above&lt;/em&gt; the wing is even less practical from a design/physics standpoint), effectively creating an even smaller limit to the size of the aircraft that can fit at the terminal since there is now a jetway that needs to reach the rear doors.  As you can see, the space between aircraft is already tight:  &lt;img src=&quot;https://i.stack.imgur.com/sGxM3.jpg&quot; alt=&quot;aft-capable jetway&quot; /&gt;Or, you use a simple stairway at the aft door and &lt;em&gt;allow passengers on the tarmac&lt;/em&gt;, an already busy place during aircraft turn-around, and we don't need them touching anything en route.  I highly recommend against the latter.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In many instances, during boarding, the rear and/or opposite-side doors are already in use for loading/unloading food and drinks and taking out the trash.  So you'd have to redesign that process.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Humans are generally stupid in large groups.  Southwest notwithstanding, your typical airline assigns seats.  Imagine a passenger entering the rear door with seat 1A.  It doesn't have to be that extreme.  It can be any seat assignment more forward than another passenger coming the opposite direction down the aisle, which has the effect of halting both directions of travel.  Passengers already sit in the wrong seats, or travel with babies, or carry too much luggage (or stow it selfishly).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;There have been many studies on efficient boarding methods.  The most efficient algorithm seems to be &lt;a href=&quot;http://arxiv.org/pdf/1108.5211v1&quot; rel=&quot;noreferrer&quot;&gt;the Steffen Method&lt;/a&gt;, but this method requires someone with an inordinate attention to detail (and willing passengers) to line people up in a specific order.  Taking into account crew resources, the most efficient method is by window-middle-aisle groups, then by random order (i.e. &amp;quot;single-zone&amp;quot;), with typical &amp;quot;zone boarding&amp;quot; least efficient.&lt;/p&gt;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&lt;p&gt;There are scenarios where boarding from both ends makes sense and is feasible, e.g. smaller planes with fewer passengers.  On larger aircraft, the problem compounds itself as the number of passengers grows, each &amp;quot;collision&amp;quot; incident affecting that many more people in the queue.  Minimizing collisions requires airlines to throw more resources at the problem, namely personnel to direct traffic.  Ask any CFO - more often than not, human resources is the most significant slice of the operating budget.&lt;/p&gt;&#xA;&lt;p&gt;In any case, engineering a solution should not entail best-case scenarios; it should be designed for typical-case at best, and more commonly for worst-case.  The human factor is one that cannot be overlooked.  There is no such thing as an idiot-proof system.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-03T01:39:11.807" CommentCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="12312" PostTypeId="2" ParentId="12308" CreationDate="2015-02-02T04:05:27.363" Score="2" Body="&lt;p&gt;The airplane is going to have established weight and CG limits already established (unless you are asking about test planes, which I feel would be an entirely different question and answer).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, there are very quick methods for calculating weight and balance during flight for both shifting weight, and dropping weight.  On my NIFA (National Intercollegate Flight Association) flight team we practice these type of formulas all the time.  Using a CR (or even E-6B) you can follow these formulas to find what the CG will be after dropping a known weight from a known arm.  Any pilot will know the amount and location of the payload or &quot;ordinance&quot; before dropping it, as well as running these calculations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's some note cards that I have.  On here you can see the formulas for weight shifted (2d down on the right) as well as weight added or removed (bottom left).  If you have any questions about these type of calculations feel free to ask. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JOpuD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2015-02-02T04:14:55.377" LastActivityDate="2015-02-02T04:14:55.377" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12316" PostTypeId="1" AcceptedAnswerId="12326" CreationDate="2015-02-02T04:53:22.163" Score="4" ViewCount="1391" Body="&lt;p&gt;I was reading about the (very) short takeoff and landing capabilities of the &lt;a href=&quot;http://justaircraft.com.au/superstol/&quot; rel=&quot;nofollow&quot;&gt;SuperSTOL&lt;/a&gt; light aircraft and it occurred to me that it would be pretty easy to set down in a national park or other remote area so long as there was a reasonably flat clearing and visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what are the regulations regarding legally landing in such places?&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-02-02T09:26:50.040" Title="Is it legal to land aircraft in national parks and state forests in Australia?" Tags="&lt;regulations&gt;&lt;australia&gt;&lt;casa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12317" PostTypeId="2" ParentId="12308" CreationDate="2015-02-02T05:51:53.933" Score="14" Body="&lt;p&gt;First, let's agree that when we say CG we're talking about the longitudinal CG, not the lateral or vertical CG.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every aircraft has a basic operating weight, typically abbreviated b.o.w. or just BOW. The BOW is the empty weight of the aircraft + the required crew + undrainable fluids. For this BOW there is a known CG. The BOW and it's CG are the base values from which further calculations proceed. If you add or remove a part of the aircraft, you have changed the BOW and its CG, and even though the change may be small, it's important to recalculate the new BOW and its CG because you now have a new baseline. If you later load the aircraft right up to a weight limit or against a CG limit but use an old baseline rather than the new one, you may exceed weight or CG limits or both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now you load the aircraft: passengers, cargo, fuel, armaments, whatever. Let's say one of the items is the 2,000 lb bomb referred to in a previous comment. If that bomb happens to be right on the CG, when you release it your weight drops by 2,000 lbs, but your CG will not have changed. If, say, the CG of the bomb was 10&quot; forward of the CG of the aircraft + the bomb, when you release the bomb you will change the CG moment by 20,000 inch-lbs. The usual convention is that forward is negative, aft is positive, so you would have incurred a -20,000 inch-lbs movement. As long as the resulting CG is still within the forward and aft limits, all is well, but you'll need to trim out your increased pitch because your CG has moved aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that if your bomb was only 200 lbs but it was 100&quot; forward of the existing CG, you would get the same moment change since 10 x 2,000 = 100 x 200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you're doing an airborne offload of a large truck out of a C-17. Further, let's say that just prior to the drop your CG is close to the aft CG limit for normal sustained flight. When you drop the truck it has to move to the rear before going out the back, but that happens quickly and you have enough airspeed that the elevator can counter the momentary movement of the CG past the normal aft limit for sustained flight. If the truck should become stuck just before dropping, you'd have a serious problem. See &lt;a href=&quot;https://www.youtube.com/watch?v=uIjO0sKBDDw&quot;&gt;the Bagram 747 video&lt;/a&gt; for what happens when a vehicle shift in flight puts the CG way aft of the limit. &lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-02-02T05:57:04.163" LastActivityDate="2015-02-02T05:57:04.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12318" PostTypeId="2" ParentId="12308" CreationDate="2015-02-02T06:02:47.810" Score="15" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;the aircraft I worked on in the army were deadlined whenever 1% of total aircraft weight was removed, requiring either the part to be reinstalled or a total reweigh prior to next flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's for internal equipment, which will affect the empty CG data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircraft lose weight during a trip. Aircraft designed to lose a lot of weight all of a sudden ( C-5 airdrops, B-52 carpet bombing ) have the details and limits calculated during the design. In the case of bombers, the ordinance will be hanging near the wings and will have a specific release order, usually back to front. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tailgate aircraft dropping something will also have very specific procedures based on the weight of the pallet going out the back door. If it's delivering pizzas the procedure is along the lines of &quot;whenever, dude&quot;. If it's a tank, it has to be positioned and locked down until the moment of release.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above is very noticeable by the flight crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the load stays (or gets stuck) on the back ramp, you're usually done. I used to skydive - 10 people on the back end of a smaller tailgate like a Casa can and do cause the plane to stall. The rules were stay at the front until it's your turn, then position and exit in a prompt manner. If the buzzer goes, let go NOW. Unlike a cargo plane, jump planes have 12,000 feet to recover from the stall. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-02-02T06:02:47.810" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12319" PostTypeId="2" ParentId="9440" CreationDate="2015-02-02T06:18:37.877" Score="1" Body="&lt;p&gt;The Mode_S closed-group on Yahoo Groups has documented many of the allocation algorithms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://groups.yahoo.com/neo/groups/Mode_S/info&quot; rel=&quot;nofollow&quot;&gt;https://groups.yahoo.com/neo/groups/Mode_S/info&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apply to join and explain your motivations.  They have an extensive Files section.&lt;/p&gt;&#xA;" OwnerUserId="7111" LastActivityDate="2015-02-02T06:18:37.877" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12320" PostTypeId="1" AcceptedAnswerId="12322" CreationDate="2015-02-02T06:25:13.703" Score="8" ViewCount="1462" Body="&lt;p&gt;In flying schools, there are aircraft designated for training student pilots. Do these aircraft have special equipments or controls on-board which are used by instructors? &#xA;Like maybe extra panels or something?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="2171" LastEditDate="2015-02-02T19:20:12.530" LastActivityDate="2015-02-03T19:00:11.887" Title="How do trainer aircraft differ from non-trainer versions?" Tags="&lt;trainer&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12321" PostTypeId="2" ParentId="12300" CreationDate="2015-02-02T06:56:00.627" Score="4" Body="&lt;p&gt;I wouldn't want all of the connections for pressurisation, air conditioning, lighting, water, IFE etc etc connected and disconncted every flight.  A maintenance and safety headache.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-02-02T06:56:00.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12322" PostTypeId="2" ParentId="12320" CreationDate="2015-02-02T07:34:45.200" Score="11" Body="&lt;p&gt;The short answer is that there's no real difference between a &quot;trainer&quot; aircraft and an &quot;owner&quot; aircraft when they roll off the manufacturer's assembly line.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below are two mid-1970s Piper Cherokee Cruisers - take my word for it that they both have virtually identical instruments, avionics, and interior finishing. One of these airplanes is the &quot;trainer&quot; I did much of my early training in, and had a little over 11,000 hours of flight time as of when the school sold it. The other is (probably) an owner-flown airplane with about 2,000 hours of flight time.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/LTiwPm.jpg&quot; alt=&quot;N2269Q&quot;&gt; &lt;img src=&quot;https://i.stack.imgur.com/5Qjsqm.jpg&quot; alt=&quot;N32711&quot;&gt;&lt;br&gt;&#xA;Can you tell which is which? The answer is in the spoiler box at the end of this post.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&quot;Trainer&quot; aircraft generally have flight and operational characteristics that makes them &quot;suitable for use in training&quot; -- though what that means &lt;a href=&quot;http://www.airbum.com/articles/ArticlePerfectTrainer.html&quot; rel=&quot;noreferrer&quot;&gt;is a subject of some debate&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern training aircraft you'll almost always find the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Dual controls&lt;/strong&gt;&lt;br&gt;&#xA;Much like a Driver's Education car has an extra brake, aircraft used for training will have dual controls so your flight instructor can correct any mistakes the student makes before they become dangerous.  (Dual controls are in fact required for flight training, at least under FAA regulations, though interestingly &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-FAA-issues-new-interpretation-of-dual-controls&quot; rel=&quot;noreferrer&quot;&gt;dual brakes are &lt;em&gt;not&lt;/em&gt; required&lt;/a&gt;.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;2-4 person seating capacity&lt;/strong&gt;&lt;br&gt;&#xA;Hand in hand with dual controls goes dual seating - You need a place for both a student and an instructor.&lt;br&gt;&#xA;You don't generally find many trainers that will seat more than four people, as those larger aircraft cost more to purchase and operate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Some kind of intercom&lt;/strong&gt;&lt;br&gt;&#xA;Students and instructors generally wear headsets, and an intercom system makes it easier for them to communicate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;One or more Radio systems&lt;/strong&gt;&lt;br&gt;&#xA;Part of flight training includes learning how to communicate with Air Traffic Control and other pilots, and how to use radio navigation systems. This requires at least a communication radio, so there's usually one either installed or available (a handheld unit), and in most modern trainers you'll find one or more navigation radios of various types.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In addition trainer aircraft tend to be inexpensive to maintain (mechanically simple), operate (relatively fuel-efficient), and tend toward the slower end of the speed spectrum (because it's easier for a student to keep up with a slower aircraft).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It's important to note that not all &quot;trainers&quot; fit this mold: The &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_T-6_Texan&quot; rel=&quot;noreferrer&quot;&gt;T-6 Texan&lt;/a&gt; is, by designation, a &lt;b&gt;T&lt;/b&gt;rainer aircraft, but its goal was to train Air Force pilots, many of whom would go on to air combat roles. The things a T-6 is optimized to teach are very different from what a Piper Cherokee or Cessna 172 are optimized to teach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Not surprisingly many of those same characteristics are also desirable in a plane you might buy to fly yourself: Dual controls in case you take a friend or another pilot along (or in case you want to take instruction in your own aircraft), an intercom to let you talk to your passengers, and radios so you can navigate and communicate in the air traffic system.&lt;br&gt;&#xA;Because of this many pilots who elect to buy an airplane purchase what we would consider &quot;trainer-class&quot; aircraft, frequently models similar to the ones they trained in (and in the used market, frequently aircraft that &lt;em&gt;were&lt;/em&gt; used for flight training at some point).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you leave the &quot;trainer&quot; range you tend to find faster aircraft, more complicated systems, more attractive finishing elements (plush cabin interiors, fancy paint schemes), and more seating capacity.&lt;br&gt;&#xA;You also find aircraft that begin to specialize more: Where trainers tend to be well-rounded the &quot;non-trainer&quot; planes tend to excel in specific areas, serving specific niches in the market (the &lt;a href=&quot;http://en.wikipedia.org/wiki/Extra_EA-300&quot; rel=&quot;noreferrer&quot;&gt;Extra 300&lt;/a&gt; is a high-performance aerobatic aircraft favored by many airshow performers, &lt;a href=&quot;http://en.wikipedia.org/wiki/Mooney_Aviation_Company&quot; rel=&quot;noreferrer&quot;&gt;Mooney aircraft&lt;/a&gt; feature extensive speed optimizations and are favored by many pilots who use their planes for long-distance travel, the &lt;a href=&quot;http://www.piper.com/aircraft/m-class/mirage/design/&quot; rel=&quot;noreferrer&quot;&gt;Piper Mirage&lt;/a&gt; is a &quot;luxury&quot; cruiser/transportation aircraft suitable for flying corporate executives to and from smaller airports, etc.).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; N2269Q is the trainer, now sporting a shiny new paint job.&lt;br&gt;&#xA; N32711 is the owner-flown airplane, with its factory paint. (&lt;a href=&quot;http://www.trade-a-plane.com/detail/aircraft/Single+Engine+Piston/1974/Piper/Cherokee+140/2046368.html&quot; rel=&quot;noreferrer&quot;&gt;Trade-a-Plane ad&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-02-03T01:17:54.550" LastActivityDate="2015-02-03T01:17:54.550" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12323" PostTypeId="1" AcceptedAnswerId="12324" CreationDate="2015-02-02T08:26:41.947" Score="14" ViewCount="1611" Body="&lt;p&gt;I've heard that before landing an airliner, the pilots perform a mini-briefing to agree on what they will do and what they can do if something goes wrong during the approach and landing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Is this true?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is it called? (my best guess would be &quot;approach briefing&quot;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What elements does the briefing contain?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="4067" LastEditDate="2015-02-02T14:28:23.910" LastActivityDate="2017-01-10T07:56:34.433" Title="What are the elements of an approach briefing?" Tags="&lt;airliner&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12324" PostTypeId="2" ParentId="12323" CreationDate="2015-02-02T08:42:09.333" Score="17" Body="&lt;p&gt;Yes, it's true.  Usually called approach or arrival briefing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Details will vary according to aircraft and operator but a typical list is NATS:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;N&lt;/strong&gt;OTAMs&lt;sup&gt;1&lt;/sup&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;A&lt;/strong&gt;TIS&lt;sup&gt;2&lt;/sup&gt; notes, chart briefing point by point, date, frequencies, courses, minimums and missed approach procedures.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;T&lt;/strong&gt;errain, minimum safety altitude, which route  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;S&lt;/strong&gt;pecial notes for arrival, taxiing, likely gate for arrival?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I noticed that you specifically asked about something going wrong.  The following assumes a serviceable aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to operator, if the aircraft is not on a stabilised approach by 1,000 feet, a go around will be performed and the missed approach procedure (MAP) followed.  The MAP is printed on the approach chart.  The initial action is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;to get the aircraft safely climbing away (aviate) &lt;/li&gt;&#xA;&lt;li&gt;to the altitude and heading defined in the MAP (navigate)&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;then call ATC to let them know (communicate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Aviate, navigate, communicate,&lt;/em&gt; always in that order.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A stabilised approach might differ between operators but is essentially.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The flight path is correct with only minor changes in pitch and&#xA;  heading needed to stay on it. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No more than 20 kts above the approach reference speed briefed as above. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Correctly configured for landing (flaps, slats, gear, spoilers armed, autobrake set etc) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Checklists completed &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Rate of descent &amp;lt;= 1,000 fpm &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Power setting is appropriate&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There may be other special checks for some types of approaches which must have been briefed as above).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The MAP might be something like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;Maintain runway heading and climb to 1500' until reaching 4 DME.  Turn right heading 250 degrees and climb to 5000' to join the hold at DISNEY&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MAP is unique for each approach so must be briefed in advance.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/NOTAM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Notice to Airmen&lt;/a&gt;: Warn of recent changes, temporary restrictions, equipment malfunctions etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service&quot; rel=&quot;nofollow noreferrer&quot;&gt;Automated Terminal Information Service&lt;/a&gt;: A continuous broadcast of airfield information such as weather, special precautions, runways in use etc.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2017-01-10T07:56:34.433" LastActivityDate="2017-01-10T07:56:34.433" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12325" PostTypeId="2" ParentId="12309" CreationDate="2015-02-02T08:45:05.313" Score="11" Body="&lt;p&gt;Some &lt;a href=&quot;http://www.telegraph.co.uk/travel/travelnews/9703428/Easyjet-offers-allocated-seating-on-all-flights.html&quot;&gt;lowcost airlines&lt;/a&gt; use both ends to speed up both loading and unloading the passengers. Moreover, for huge aircrafts (A380 and B747), you may use &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380#Integration_with_infrastructure_and_regulations&quot;&gt;several jetways&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2015-02-02T08:45:05.313" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12326" PostTypeId="2" ParentId="12316" CreationDate="2015-02-02T09:02:05.757" Score="6" Body="&lt;p&gt;The answer to your question, is &lt;em&gt;yes and no&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAR 92 (1) states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft shall not land at, or take-off from, any place unless: ... (d) the place... is suitable for use as an aerodrome for the purposes of the landing and taking-off of an aircraft; and, having regard to all the circumstances of the proposed landing or take-off (including the prevailing weather conditions), the aircraft can land at, or take-off from, the place in safety. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see, you are able to takeoff and land away from a proper aerodrome provided it is safe to do so. As you can see &lt;a href=&quot;http://atsb.gov.au/publications/investigation_reports/2013/aair/ao-2013-151.aspx&quot;&gt;here&lt;/a&gt;, misjuding this level of safety can be fatal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Civil Aviation Advisory Publication (CAAP) 92-1(1) provides guidelines on what constitutes a safe landing/takeoff field other than an aerodrome. These safe areas are known as Aeroplane Landing Areas. Although the CAAP is only a guide, it is highly recommended that any area you choose to operate from meets these minimum standards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you are allowed to takeoff and land outside of an actual aerodrome. But your question includes national parks. The rules surrounding these are outside of my knowledge (and they vary from state to state) , but I do know that many parks carry restrictions on vehicle entry, and the types of activities permitted. I would therefore find it very surprising if you received permission to land a plane in their park (if you found a safe landing site in the first instance).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Some commercial flying is permitted within national parks. For instance, they use helicopters and a person on a sling rope to collect crocodile eggs in Kakadu. Obviously then some activities can be approved in a national park. I'd say it all depends on the specific park and the activity being performed. Private flying away from an aerodrome? You would have to check. In any case, my answer to your question is you can land out bush somewhere but possibly not in a national park. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2015-02-02T09:26:50.040" LastActivityDate="2015-02-02T09:26:50.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12327" PostTypeId="1" AcceptedAnswerId="12330" CreationDate="2015-02-02T09:29:02.520" Score="18" ViewCount="13209" Body="&lt;p&gt;I am developping an ATC radar for a simulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think there is any standard for radars to show aircraft data on radar screens.&#xA;But there should be general data to show on radar screens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;CALL SIGN&#xA;ALT ASSIGNED ALT&#xA;SPEED HEADING&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can the data shown be changed on the clients?&lt;/li&gt;&#xA;&lt;li&gt;Is there a difference between ground radar and air radar displayed data?&lt;/li&gt;&#xA;&lt;li&gt;Is there any standard or can you give me any examples?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7115" LastEditorUserId="97" LastEditDate="2015-05-03T01:33:28.700" LastActivityDate="2018-12-05T09:06:36.787" Title="What data is displayed on civilian ATC radar screens?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;&lt;software&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12328" PostTypeId="1" AcceptedAnswerId="12329" CreationDate="2015-02-02T09:35:05.640" Score="1" ViewCount="530" Body="&lt;p&gt;How do modern aircraft steer on the ground? Do they have a steering wheel which moves the front wheel (left/right).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see that there is a Tug vehicle which pushes the aircraft backwards, so the aircraft does not have a reverse gear for sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the aircraft use the Engine thrust to move forward on the ground or does it have separate motor which propels the wheels?&lt;/p&gt;&#xA;" OwnerUserId="7065" LastEditorUserId="572" LastEditDate="2015-02-02T09:38:50.503" LastActivityDate="2015-02-03T16:13:54.753" Title="How do aircraft steer on ground?" Tags="&lt;ground-operations&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-02-02T11:12:24.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="12329" PostTypeId="2" ParentId="12328" CreationDate="2015-02-02T09:39:40.557" Score="2" Body="&lt;p&gt;All of these methods are used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nosewheel steering is common on most commercial aircraft using a tiller.  Rudder, differential braking, differential thrust and even motors in the wheels (experimental only as far as I know) are also used, &lt;a href=&quot;https://www.youtube.com/watch?v=Xz_eU_l0vMs&quot; rel=&quot;nofollow&quot;&gt;as seen in this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine thrust is used to move forward but differential thrust might also be used when negotiating tight turns. &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Landing_gear#Steering&quot; rel=&quot;nofollow&quot;&gt;(Details here)&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="65" LastEditDate="2015-02-03T16:13:54.753" LastActivityDate="2015-02-03T16:13:54.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12330" PostTypeId="2" ParentId="12327" CreationDate="2015-02-02T10:29:57.010" Score="19" Body="&lt;p&gt;There are a few different ATC Systems and Radar Screens being used throughout the world, so there will be no set standard which applies globally, as vendors and setup differ.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATC screen can be adjusted to show what information the controller needs, and some items are universal to all positions being served (Callsign, Speed, Altitude, Assigned Altitude), some items are not required on each position to be displayed on the radar tag (Squawk, Routing, Aircraft Type, Wake Turbulence Category).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4omyX.jpg&quot; alt=&quot;P1 Radar Target - correlated&quot;&gt;&lt;br&gt;&lt;sup&gt;Source: www.andreas-milde.de&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0jbp.gif&quot; alt=&quot;EuroScope Target&quot;&gt;&lt;br&gt;&lt;sup&gt;Source: www.euroscope.hu / Air Traffic Simulation Client&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wCUoJ.jpg&quot; alt=&quot;Frankfurt Airspace&quot;&gt;&lt;br&gt;&lt;sup&gt;Source: fluglotse.wordpress.com&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-02-02T10:29:57.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12331" PostTypeId="2" ParentId="8602" CreationDate="2015-02-02T10:38:58.330" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot; rel=&quot;nofollow&quot;&gt;Flight 587&lt;/a&gt; was undergoing violent yaw rotations before the vertical stab snapped. Once it was lost, nothing stopped the plane's rotation and it just continued to yaw until entering a spin. If the vertical stabilizer had simply come off while the plane was in normal flight,  then who knows if it would have survived to land, but it probably would not have instantly spun out of control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other instances where planes crashed after losing the vertical stab are the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie#Incidents_and_accidents&quot; rel=&quot;nofollow&quot;&gt;XB-70&lt;/a&gt;, where it lost both its vertical stabs after a collision, and &lt;a href=&quot;http://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision&quot; rel=&quot;nofollow&quot;&gt;DHL Flight 611&lt;/a&gt;, also lost its vertical stab due to a collision. Flight 611 survived longer than the aircraft it struck, but broke up soon after due to stresses put on the plane from the violent yawing and dive. It should be noted that a modern airliner would lose its crucial hydraulics if the fin detaches, rendering all control surfaces unusable.&lt;/p&gt;&#xA;" OwnerUserId="7117" LastEditorUserId="65" LastEditDate="2015-02-04T19:39:02.137" LastActivityDate="2015-02-04T19:39:02.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12332" PostTypeId="2" ParentId="12300" CreationDate="2015-02-02T10:56:36.780" Score="6" Body="&lt;p&gt;Passenger crates were envisaged a long time ago. Apart from the above objections, may I add this: A passenger crate in a plane is a box in a box. This would worsen claustrophobia which is already a problem. A view outside would alleviate this, but requires windows. Crate windows would need to be aligned with fuselage portholes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The psychological problem is doubled by a physical problem which is emergency evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any project would need a highly standardised crate compatible with competing aircraft types. This standard would later become a constraint for future design innovation. It would also limit customisation of planes by constructors for specific customers.&lt;/p&gt;&#xA;" OwnerUserId="7118" LastActivityDate="2015-02-02T10:56:36.780" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12333" PostTypeId="2" ParentId="12189" CreationDate="2015-02-02T11:57:09.183" Score="7" Body="&lt;p&gt;Caging was required when Gyros were mechanical masses actually spinning at many rpms in their cases. That mass resisted rotational motion and produced a &lt;strong&gt;&lt;em&gt;resistance force&lt;/em&gt;&lt;/strong&gt; that was measured and translated into useful info like pitch and roll. That spinning mass carried much momentum in the form of its mass times its rotational velocity. And too much sudden motion and the &lt;strong&gt;&lt;em&gt;resistive force&lt;/em&gt;&lt;/strong&gt;/momentum could  cause mechanical stress to the unit and/or cause the instrument to tumble. So it became helpful to cage a gyro before acrobatics to keep the thing from busting or wearing out prematurely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern glass cockpits like the G1000, there are no mechanical gyros with high mass parts (excepting a standby instrument independent of the glass system, which may need caging if it's a mech type). The gyros that are used for a G1000 system are called MEMS (micro electro mechanical system) gyros which do not have a spinning mass. They have tiny metal discs that merely vibrate. When they are rotated (by pitching or rolling), the vibration dynamics change a little bit and a capacitive reactance apparatus measures this change which is directly proportional to the rate of rotation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MEMS gyros can take aerobatics without enduring any mechanical stress what so ever so there is no need to cage them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system does however, loose accuracy. The rotation rates offered by the MEMS gyros are prone to micro errors and these errors add up over time. The more rotations, the sooner the sum of all errors becomes significant. There is a software algorithm that re-aligns the system periodically and basically erases the errors (it kind of reminds the system which way is up). The algorithm uses accelerometers (like the one in your phone) to sense stable, un-accelerated motion, and at that time, the accelerators can sense gravity which points straight down. When this occurs, pitch and roll angles are keyed off the accelerometers and the rotation rates are reset to zero and the system is ready to start keying off the gyros again and adding up errors. In normal flight like touch and goes or cross country flight, there are lots of opportunity to reset the errors. In aerobatic flight there are fewer opportunities but once the aircraft eventually returns to level flight for some period of time, it will reset itself. Whether or not the error can be significant enough to be noticed by the pilot, I don't know... probably depend on many factors, but I'd probably be intimate with a sic sack by then.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="340" LastEditDate="2015-02-02T15:19:31.397" LastActivityDate="2015-02-02T15:19:31.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12334" PostTypeId="2" ParentId="3864" CreationDate="2015-02-02T12:03:34.383" Score="7" Body="&lt;p&gt;I think you gentlemen have missed the point.  Ercoupe aicraft have no rudder pedals at all. The flight controls are designed to keep the aircraft in coordinated flight automatically, thus eliminating the need for the pilot to use the rudder. Since it is possible to build and fly airplanes without rudder pedals Wolfgang is correct. His main objective in pointing this out to the pilot is to emphasize that in the air the rudder does NOT cause the aircraft to turn.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wolfgang also points out legitimate uses of rudder pedals if the airplane has them, or more precisely, MUST have them because of design inadequacies that leave the designer no choice but to make rudder pedals available to the pilot to address undesirable flight characteristics in certain modes of flight. But again, in the air the rudder does NOT cause the aircraft to turn.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wolfgang did not need to recant his position on rudder pedals because he was correct. He did miss that the trend towards building automatically coordinated flight controls would be short lived. No doubt in 1944 he believed the Ercoupe was the start of things to come. This is understandable considering that no man can predict the future.  &lt;/p&gt;&#xA;" OwnerUserId="7120" LastEditorUserId="8531" LastEditDate="2017-11-15T07:53:04.627" LastActivityDate="2017-11-15T07:53:04.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12336" PostTypeId="1" AcceptedAnswerId="12338" CreationDate="2015-02-02T15:19:12.037" Score="5" ViewCount="957" Body="&lt;p&gt;As you can see &lt;a href=&quot;http://skyvector.com/?ll=31.51580564437983,-82.16400146836585&amp;amp;chart=302&amp;amp;zoom=6&amp;amp;plan=V.K7.CRG:V.K7.DBN&quot;&gt;here&lt;/a&gt;, V267 has a length of 149nm, is defined by the Craig VOR (CRG) and the Dublin VOR (DBN) and has a MEA of 3000. &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html#CwA1d6ROBE&quot;&gt;According to the AIM&lt;/a&gt;, the Service volumes of VORs never reach more then 40nm underneath 14,500ft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, the Craig VOR or rather VORTAC is described to have the Standart High Altitude Service Volume in the A/FD, but at the MEA, which should also guarantee reception of the navaids in use, the range is still only 40nm. A route at that altitude between those two navaids should only be &amp;lt;80nm, so how can it be 149nm?&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="572" LastEditDate="2015-02-02T15:27:59.793" LastActivityDate="2015-02-02T15:52:12.800" Title="How are there some Victor airways that exceed the service area of the VORs they are identified by?" Tags="&lt;faa-regulations&gt;&lt;range&gt;&lt;vor&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12338" PostTypeId="2" ParentId="12336" CreationDate="2015-02-02T15:52:12.800" Score="13" Body="&lt;p&gt;It says it &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html#ncG212JACK&quot;&gt;right there on the page where the service volumes are described in the AIM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1-1-8. Navigational Aid (NAVAID) Service Volumes&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Standard Service Volume &lt;strong&gt;limitations do not apply to published IFR&#xA;  routes&lt;/strong&gt; or procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So V267 has been flown at the MEA by an FAA plane, and it obviously met the signal accuracy requirements to be usable at the distances charted.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-02-02T15:52:12.800" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12339" PostTypeId="2" ParentId="12304" CreationDate="2015-02-02T16:30:31.690" Score="6" Body="&lt;p&gt;I think this depends on what &quot;FAA-qualified&quot; means: the FAA defines aerobatic flight in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1303&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.303&lt;/a&gt; but it doesn't issue any pilot certificates or ratings for aerobatics. I did find several references to &lt;em&gt;FAA Form 8710‑7, Statement of Acrobatic Competency&lt;/em&gt; (e.g. &lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v05%20airman%20cert/chapter%2009/05_009_001rev1.htm&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;), but the form itself isn't even listed on the &lt;a href=&quot;https://www.faa.gov/forms/&quot; rel=&quot;nofollow&quot;&gt;FAA's form page&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an FAA &lt;a href=&quot;https://www.faasafety.gov/files/notices/2012/Mar/Guidelines_for_All_Attitude_Training.pdf&quot; rel=&quot;nofollow&quot;&gt;document&lt;/a&gt; called &lt;em&gt;Guidelines for Pilots Seeking All-Attitude Training&lt;/em&gt; which states that there is no special certification required:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] no separate certificate, rating or endorsement is required to&#xA;  specifically qualify an individual as an all-attitude instructor&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Anyone claiming to be an all-attitude instructor must at least hold a&#xA;  valid Commercial certificate if working for compensation or hire. The&#xA;  instructor must also be a certificated flight instructor (CFI) to&#xA;  provide FAA endorsements. Other than that, CFI credentials are not&#xA;  necessary for anyone to claim to be an all-attitude instructor.&#xA;  Therefore, &lt;em&gt;caveat emptor&lt;/em&gt; - buyer beware - applies when seeking&#xA;  instruction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although their definition of &quot;all-attitude&quot; isn't exactly the same as &quot;aerobatic&quot;, the document seems to make it clear that aerobatic training is not directly regulated. And looking through a variety of aerobatic websites including the &lt;a href=&quot;https://www.iac.org/&quot; rel=&quot;nofollow&quot;&gt;IAC one&lt;/a&gt;, there is no mention of any required FAA certification. Endorsements for tailwheel, high-performance or complex aircraft are often required, but that's because of the aircraft itself, not the aerobatic activity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this &lt;a href=&quot;http://rotornation.com/chuck-aaron/&quot; rel=&quot;nofollow&quot;&gt;profile&lt;/a&gt; gives some clearer information:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once the helicopter was ready, the FAA needed to certify it in order&#xA;  for Chuck to perform stunts with it. Once the aircraft was certified,&#xA;  the next step was to also get him certified, which ended up being a&#xA;  complicated process. The FAA was not sure how they could certify him,&#xA;  so they turned to Rich Lee, chief pilot for Boeing, who evaluated him.&#xA;  “He wanted to make sure that I did have all my screws in my head and&#xA;  that they were not loose”, said Chuck, laughing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My guess is that the FAA first issued a new airworthiness certificate and/or waiver for the modified helicopter. That's very common and it would be same for a home-built aircraft, for example. Second - and this is a guess - they had the Boeing guy evaluate him for the Statement of Acrobatic Competency that I mentioned above. Although I can't find it on the FAA site, it obviously existed in the past and if you look at &lt;a href=&quot;http://www.warbirds-eaa.org/forms/3Acrobatic%20Competency%20FAA%20Form%208710.7.pdf&quot; rel=&quot;nofollow&quot;&gt;this example&lt;/a&gt; from the EAA Warbirds site, you can see that the evaluation process was (is?) 'outsourced' by the FAA anyway, presumably because they have no experts available internally:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I desire to take advantage of an FAA procedure for the evaluation of&#xA;  my competency by a Warbird Aerobatic Evaluator (Warbird Evaluator) on&#xA;  the list maintained by the EAA Warbirds of America, Incorporated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I suspect that putting a unique airworthiness certificate together with a unique Statement of Acrobatic Competency resulted in a uniquely &quot;FAA-qualified&quot; acrobatic helicopter pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, according to Aaron's &lt;a href=&quot;https://www.linkedin.com/pub/chuck-aaron/8/b62/372&quot; rel=&quot;nofollow&quot;&gt;LinkedIn page&lt;/a&gt; he is the:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First FAA Certified Helicopter Pilot to recieve a Helicopter Aerobatic&#xA;  Certificate from the FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That again seems to emphasize the helicopter, not the pilot. &lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-02-07T18:06:36.547" LastActivityDate="2015-02-07T18:06:36.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12340" PostTypeId="2" ParentId="11906" CreationDate="2015-02-02T16:51:59.500" Score="10" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You MUST NOT allow the EGT or ITT (whichever is applicable) temperature limit to be exceeded in any turbine engine. If it gets close to occurring during start on a PT-6, you need to abort the start by stopping fuel flow into the engine, then conduct the appropriate checklist for an aborted start. Unlike the Honeywell / Garrett TPE single-shaft engines, the PT-6 normally won't get close to the temperature limit on start. The Garretts I used to fly in Metroliners had to get right next to redline and stay there on every start. One reason that PT-6 engines are so much more relaxing to fly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On takeoff / climb, just don't exceed the maximum temp limit; regulate the power lever(s) to keep below it. I've never had a failure of a Pratt except for bleed air leaks.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airlines count cycles as a start, flight, and shutdown. If one of these did not occur, you did not have a cycle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7123" LastActivityDate="2015-02-02T16:51:59.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12341" PostTypeId="1" AcceptedAnswerId="12343" CreationDate="2015-02-02T16:53:22.243" Score="13" ViewCount="929" Body="&lt;p&gt;I'm shopping for my first aircraft.  I have found a very well cared for 172 that is VFR.  I also found an IFR-certified 172 that is higher time and cosmetically is showing its age.  I inquired about the expense of updating the VFR plane to IFR and the seller mentioned that due to some upcoming changes in IFR requirements even a plane that is IFR rated today may require a substantial investment to keep it IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've done a lot of searching and can't find anything to substantiate that statement.  The closest thing I found was an article from the AOPA way back in 1997 where the FAA had proposed rule changes that would have made a lot of (then) IFR compliant GPS units non-compliant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What, if any, regulatory changes are on the horizon that might render the IFR certified equipment I buy today worthless tomorrow in the context of IFR?&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="167" LastEditDate="2015-02-02T18:14:51.560" LastActivityDate="2015-02-02T23:31:17.640" Title="What coming changes might render current IFR equipment worthless in the foreseeable future?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;avionics&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12342" PostTypeId="2" ParentId="12320" CreationDate="2015-02-02T17:17:27.507" Score="5" Body="&lt;p&gt;To give a general answer, it is important to define what makes an aircraft suitable as a trainer:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It must load at least two people. But also rarely more than two. Therefore, most trainers are two-seaters or half-empty four seaters. They come with dual controls and - in case of tandem seating - two sets of instruments, and none to little modification is needed.&lt;/li&gt;&#xA;&lt;li&gt;It must fly slowly and be naturally stable. Slow aircraft leave you more time to do the flying, traffic monitoring, radio communication and what else is asked of a proper pilot. Natural stability makes flying much easier, and it helps to avoid the cost and complexity of a computerized flight control system which could compensate for the instability. Propeller aircraft of a conventional layout fit well here, and only advanced training is done on jets.&lt;/li&gt;&#xA;&lt;li&gt;It must be cheap to operate. The physics of flying does not change with size, but the cost per flight hour certainly does. Again, GA propeller aircraft are a good fit.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now look at what those pilots will fly later in their lives:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Recreational flying: Mostly the same GA aircraft, or more advanced, but still broadly similar types.&lt;/li&gt;&#xA;&lt;li&gt;Professional civil pilots: Big turboprops or even bigger jets. If they have to earn a profit, aircraft need to be big and fast. Both characteristics disqualify them for training apart from getting a type certificate. Since they also have dual controls and are designed to be flown from both seats, they can be used for training without any modification at all.&lt;/li&gt;&#xA;&lt;li&gt;Military pilots: They fly either similar types like their civilian colleagues, or highly specialized machines with relaxed static stability, extreme power-to-weight ratios and complex electronic equipment. Now it depends what your definition of a &quot;normal&quot; airplane is - but this category of aircraft is very different from trainers. In this category there are indeed special two-seater versions especially for pilot training. In most cases, a second cockpit was added at the expense of internal tank volume, so the equipment is fully functional and identical to the combat version. See the examples below:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CdApv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Single-seat &quot;regular&quot; Eurofighter (above) and the two-seater training version (below)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cheli.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Single-seat &quot;regular&quot; MiG-21 (right) and the two-seater training version (left)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-03T19:00:11.887" LastActivityDate="2015-02-03T19:00:11.887" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12343" PostTypeId="2" ParentId="12341" CreationDate="2015-02-02T20:28:57.683" Score="19" Body="&lt;p&gt;At the moment the answer is &quot;None&quot; - with two exceptions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;LORAN receivers&lt;/strong&gt;&lt;br&gt;&#xA;These are already worthless because the US has shut down our LORAN chains.&lt;br&gt;&#xA;They are jokingly referred to as &quot;IFR-Certified Lead Bricks&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;ADFs&lt;/strong&gt;&lt;br&gt;&#xA;The FAA is killing off NDBs one by one - an ADF is basically an expensive, drag-producing AM Radio in many parts of the country, and its utility is in steady decline.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Other than that the core IFR technologies are pretty much sticking around:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;VOR/LOC/ILS&lt;/strong&gt; isn't going anywhere.&lt;br&gt;&#xA;Some VORs are getting decommissioned, but even the bleakest plans call for the FAA to maintain a &quot;minimal operational network&quot; of VORs as a backup in the event of trouble with the GPS satellites..&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;DME&lt;/strong&gt; is sticking around.&lt;br&gt;&#xA;Lots of planes flying around use DME still, and there are lots of DME approaches which serve as good backups for GPS approaches.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;(WAAS) GPS&lt;/strong&gt; is the current &quot;best technology&quot; &amp;amp; isn't going away soon.&lt;br&gt;&#xA;The FAA &lt;strong&gt;&lt;em&gt;LOVES&lt;/em&gt;&lt;/strong&gt; WAAS GPS. It lets them get ILS-type approaches to pretty much any runway without expensive ground equipment to install/maintain/test. If you have an IFR-Certified WAAS GPS in your aircraft you're on the cutting edge of IFR navigation equipment, even if the GPS itself is older-generation technology (such as the popular Garmin 430W).&lt;br&gt;&#xA;If your GPS is not &lt;a href=&quot;http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System&quot;&gt;WAAS capable&lt;/a&gt; it's still going to be usable, but it's much more limited. It may also pose some problems for you down the road (see below).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some equipment regulations are changing (as part of the &lt;a href=&quot;http://www.aopa.org/Advocacy/Air-Traffic-Services-,-a-,-Technology/Air-Traffic-Services-Brief-Automatic-Dependent-Surveillance-Broadcast-ADS-B&quot;&gt;ADS-B Out mandate&lt;/a&gt; coming in 2020), but that's not an IFR-specific thing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crux of the ADS-B Out mandate is if you want to fly in airspace where a Mode C transponder is currently required you will need two things in your aircraft (if they're not already installed):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;An ADS-B Out transmitter to broadcast your position.&lt;br&gt;&#xA;This can be achieved in two ways:&lt;br&gt;&#xA;A Mode S transponder with Extended Squitter (1090ES); or&lt;br&gt;&#xA;A 987MHz Universal Access Transceiver (UAT)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A suitably accurate position source to talk to the transmitter.&lt;br&gt;&#xA;Currently that means a WAAS GPS - either a panel-mounted device or a separate &quot;blind&quot; box.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The cost of complying with this mandate falls somewhere within a wide range: If you want a modern WAAS GPS with a touchscreen interface that will let you fly GPS approaches and a new transponder to do the broadcasting part you're going to spend a lot more money than if you install a Universal Access Transceiver and blind GPS source that do the absolute minimum required to comply.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-02-02T23:31:17.640" LastActivityDate="2015-02-02T23:31:17.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12345" PostTypeId="2" ParentId="12141" CreationDate="2015-02-03T00:26:47.100" Score="1" Body="&lt;p&gt;The physical effect that causes this drop is call the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bernoulli%27s_principle&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;Bernoulli Effect&lt;/em&gt;&lt;/a&gt;.&#xA;To compute anything reasonable, you would need to use the &lt;em&gt;Compressible flow&lt;/em&gt; equation. From this point of view, it would be easier to measure the difference and put it in the instrument failure manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short for the effect: gas with the same density presses against a non-moving object less than against a moving one. &lt;/p&gt;&#xA;" OwnerUserId="802" LastActivityDate="2015-02-03T00:26:47.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12346" PostTypeId="1" AcceptedAnswerId="12347" CreationDate="2015-02-03T09:12:23.490" Score="5" ViewCount="1363" Body="&lt;p&gt;I am developing an air traffic control radar simulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what minimum distance between two aircraft in mid-air should a conflict alert be given?&lt;/p&gt;&#xA;" OwnerUserId="7115" LastEditorUserId="3859" LastEditDate="2015-03-06T16:39:52.320" LastActivityDate="2016-10-19T18:29:40.023" Title="At what distance between two aircraft will the air traffic controller get an alarm?" Tags="&lt;air-traffic-control&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12347" PostTypeId="2" ParentId="12346" CreationDate="2015-02-03T09:23:24.773" Score="7" Body="&lt;p&gt;The STCA (Short Term Conflict Alert) or pre-alert settings depend on the radar client in use and the ACC's or ARTCC's own standard operation procedures. Some ATC systems give a warning before a loss of separation can occur if criteria are met, informing the controller of a possible conflict. Factors can be clearing aircraft on the same altitude / flight level, aircraft on converging flight profiles, lateral or vertical separation reducing below threshold values, e.g. where 5nm lateral separation is required, a STCA could be set to occur at 7nm lateral separation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The minimum radar separation between aircraft depends on airspace (&lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight/&quot;&gt;TMA area vs enroute area&lt;/a&gt;), aircraft equipment and airspace separation requirements (&lt;a href=&quot;http://en.wikipedia.org/wiki/Reduced_vertical_separation_minima&quot; rel=&quot;nofollow noreferrer&quot;&gt;RVSM vs CVSM&lt;/a&gt;), flight rules (e.g. IFR to VFR is not separated outside class C airspace in Germany) or local rules imposed by the Civil Aviation Authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general rule of thumb for IFR separation in most countries (as most countries follow RVSM rules):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;5nm lateral separation enroute (upper airspace)&lt;/li&gt;&#xA;&lt;li&gt;3nm lateral separation in TMA area (lower airspace)&lt;/li&gt;&#xA;&lt;li&gt;1.000ft vertical separation in lower and upper airspace where RVSM is observed and aircraft equipped&lt;/li&gt;&#xA;&lt;li&gt;2.000ft vertical separation in non-RVSM airspace or between aircraft not equipped for RVSM&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Oceanic separation is achieved differently, as non-radar procedures are in place. The separation in non-radar environments is achieved procedurally and through position reports and timing.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-06T15:55:35.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12348" PostTypeId="1" AcceptedAnswerId="12349" CreationDate="2015-02-03T12:35:12.640" Score="22" ViewCount="16320" Body="&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=47d74074&amp;amp;opt=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle Of Attack (AOA) probes during climb, leading to &lt;strong&gt;activation of the Alpha Protection (Alpha Prot)&lt;/strong&gt; while the Mach number increased. The flight crew managed to regain full control and the flight landed uneventfully.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is Alpha protection? &lt;/li&gt;&#xA;&lt;li&gt;Is it part of another major system (like auto-pilot)?&lt;/li&gt;&#xA;&lt;li&gt;What can it do?&lt;/li&gt;&#xA;&lt;li&gt;How is it activated?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="31425" LastEditDate="2019-08-22T17:55:26.937" LastActivityDate="2019-08-22T17:55:26.937" Title="What is Alpha protection?" Tags="&lt;flight-controls&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12349" PostTypeId="2" ParentId="12348" CreationDate="2015-02-03T12:52:49.367" Score="26" Body="&lt;p&gt;Alpha is also called &quot;Angle of Attack&quot;. It is the angle between the relative wind and the chord line of the wing. When the angle of attack is increased to a certain point, the airflow over the wing is no longer smooth. Turbulence is created after the wing, and it loses lift. This is known as a &lt;a href=&quot;https://aviation.stackexchange.com/a/6368/3386&quot;&gt;stall&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Alpha protection&quot; is a system which prevents the angle of attack from getting too high. This is done by software monitoring the plane's angle of attack sensor. When a high alpha situation is detected, the software lowers the nose of the plane to maintain high but still safe angle of attack. It also commands full thrust to all engines. This system is designed to prevent pilots from stalling the aircraft and to allow them to get the best possible performance in emergency e.g. in a wind-shear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not part of the autopilot. It is integrated into the flight control computer and activated at all times. Autopilot are functions which fly the plane in a certain way to reduce the pilot's workload in normal situations (e.g. climb to 13,000 feet, turn left to heading 340).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots can opt to turn off such protection systems should it malfunction, or a &lt;em&gt;very&lt;/em&gt; special occasion exists where these protections should be switched off, such as performing at an airshow.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Notable Accidents&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In the Airbus, the A320 was the first &quot;fly-by-wire&quot; aircraft. During a demonstration flight &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_296&quot; rel=&quot;noreferrer&quot;&gt;AF296&lt;/a&gt; when showing off the alpha-protection system the pilots took the airplane too low and too slow and disabled the part of the system that should have commanded full thrust. The plane didn't stall but was having too little energy to climb anyway. It crashed gently into the trees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an &lt;a href=&quot;http://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T&quot; rel=&quot;noreferrer&quot;&gt;acceptance flight&lt;/a&gt;, the pilots were testing the alpha-protection at low altitude. The system should have prevented the plane from pitching too high. However, to the surprise of the crew, it failed. The plane stalled with insufficient altitude to recover. The system did not work because water got into the angle-of-attack probes during previous improper washing procedure, froze during the flight and blocked the probes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;AF447&lt;/a&gt;, the system switched to &quot;alternate law&quot; and no longer provided stall protection, because the pitot tubes (airspeed sensors) froze over. The plane stalled from 38,000 feet to the water after the pilots failed to apply correct procedure for unreliable airspeed.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-02-03T15:19:51.710" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="12350" PostTypeId="2" ParentId="12348" CreationDate="2015-02-03T12:55:20.227" Score="3" Body="&lt;p&gt;Alpha protection is a safety measure that prevents an airplane going over certain values of angle of attack. Usually &quot;alpha&quot; is used to designate the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airplane is flying, if it exceeds a certain value of angle of attack it will enter a stall (less lift, sometimes suddenly, and the plane falls like a rock). Airbus introduced this safety check into the flight control system that blocks the airplane from getting closer to dangerous values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyhow pilots are able to recover from a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So alpha protection is just software on board.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="-1" LastEditDate="2015-02-03T16:26:39.743" LastActivityDate="2015-02-03T16:26:39.743" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12351" PostTypeId="2" ParentId="12300" CreationDate="2015-02-03T15:04:26.667" Score="0" Body="&lt;p&gt;My suspicion is that delays in loading passengers onto aeroplanes come from two sources:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Security &amp;amp; border concerns since the hijacking of aircraft became common in the 1970s; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Airports' desire to make money from passengers being forced to wait in airports, where they buy things from retailers who are paying tenants of the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the topic of (2) a British airport group (Heathrow is one of their properties) told shareholders around 15 years ago that they were not in the transport business, but in the retail business, pointing out that over 60% of their revenues came from rents paid by airport retailers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's elementary economics that while this is the case, airports and airlines have no incentive to make aircraft boarding quicker, even if a solution for (1) were found. Were airports to shift their revenue model away from retail, this entails airlines paying more for landing slots, so the two groups have a common interest in wasting the time of travellers by keeping them in airports for as long as possible out of their travel time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A saner approach to speeding up the loading of passengers would be - rather than loading them in boxes like freight - to simply cut the airport out and have passengers board special buses in town, check their bags and travel documents with a couple of officials who are also travelling on the bus, and have those buses drive straight onto the tarmac and up to the aeroplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is after all how very rich people travel. Someone drives them straight to the aeroplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports earning 60% of revenues from in-airport retail tenants are unlikely to support this simple idea, however. &lt;/p&gt;&#xA;" OwnerUserId="7138" LastActivityDate="2015-02-03T15:04:26.667" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12352" PostTypeId="1" AcceptedAnswerId="12381" CreationDate="2015-02-03T17:00:37.610" Score="11" ViewCount="3962" Body="&lt;p&gt;Would it be more effective to increase the length or chord of a helicopter rotor blade for better performance? (Say, 10%?)&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="6979" LastEditDate="2015-02-03T21:03:16.197" LastActivityDate="2019-01-16T19:25:10.963" Title="Would it be more effective to increase the length or chord of a rotor blade for better performance?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;&lt;rotorcraft&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12354" PostTypeId="1" AcceptedAnswerId="12355" CreationDate="2015-02-03T18:33:05.203" Score="8" ViewCount="796" Body="&lt;p&gt;In this &lt;a href=&quot;http://www.avweb.com/news/airman/184279-1.html?redirected=1&quot; rel=&quot;noreferrer&quot;&gt;AVWeb&lt;/a&gt; article, numerous references are made to &lt;code&gt;500 and 1&lt;/code&gt;, with other references to &lt;code&gt;3,000 and 5&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the statement &lt;code&gt;The current observation was 800 overcast and four miles visibility&lt;/code&gt; (in the second paragraph), I would presume that &lt;code&gt;500 and 1&lt;/code&gt; means a 500 foot ceiling and one mile visibility, is that correct?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-02-03T21:48:53.017" LastActivityDate="2015-02-03T21:48:53.017" Title="What does &quot;500 and 1&quot; mean?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12355" PostTypeId="2" ParentId="12354" CreationDate="2015-02-03T18:38:09.013" Score="9" Body="&lt;p&gt;Yes, 500 and 1 is 500 ft ceiling and 1 mile visibility.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-02-03T18:38:09.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12356" PostTypeId="1" AcceptedAnswerId="12357" CreationDate="2015-02-03T18:44:14.590" Score="32" ViewCount="9467" Body="&lt;p&gt;I never turn them on, but I do turn them off if I notice them. Is this a relic from the age when people lit up next to you and you wanted to blow away the smoke? The system must weigh almost a ton on a large aircraft and seems pretty unpopular and hard to maintain.&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-02-05T14:20:30.837" Title="Why do passenger aircraft have the little airjets over each seat?" Tags="&lt;aircraft-design&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12357" PostTypeId="2" ParentId="12356" CreationDate="2015-02-03T18:51:31.443" Score="27" Body="&lt;p&gt;The airjet openings are connected to a long duct running along the ceiling. Since the air volume inside the cabin is restricted, fresh air must be pumped into it constantly. It is bleed air from the compressor section of the engine, which is first cooled and then enters the cabin via those ducts which feed all the little vents or airjets, as you call them. Passengers can open or close them individually and direct the flow for best comfort. The general idea is that some vents will be closed, but enough are open during every flight so the needed recirculation of air can happen. If more are closed, the pressure in the duct will be higher, so the flow through the remaining vents will increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The total weight of all the cabin ducting is a minor consideration, it's only a few dozen gram per passenger.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="64" LastEditDate="2015-02-04T19:07:43.077" LastActivityDate="2015-02-04T19:07:43.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12359" PostTypeId="1" AcceptedAnswerId="12360" CreationDate="2015-02-03T19:02:48.347" Score="20" ViewCount="3657" Body="&lt;p&gt;What is the weight saving of a windowless fuselage for cargo aircraft?&#xA;Does anyone have a rough estimation?&lt;/p&gt;&#xA;" OwnerUserId="6859" LastEditorUserId="1696" LastEditDate="2015-10-07T14:41:07.150" LastActivityDate="2018-06-24T18:01:05.857" Title="What is the weight saving of windowless fuselage for cargo aircraft?" Tags="&lt;windows&gt;&lt;fuselage&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12360" PostTypeId="2" ParentId="12359" CreationDate="2015-02-03T20:08:48.157" Score="19" Body="&lt;p&gt;Let's take a Boeing 737 as a generic example, and spitball some numbers.&lt;br&gt;&#xA;I'll make the post community wiki so someone can come along and plug in more accurate numbers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aluminum has a density of 2.7 g/cm&lt;sup&gt;3&lt;/sup&gt;&lt;br&gt;&#xA;(For our purposes let's assume the skin alloy is &quot;close enough to pure aluminum&quot; because I'm too lazy to look up the proper alloy density).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plexiglass (just picking a random variety) has a density of 1.18 g/cm&lt;sup&gt;3&lt;/sup&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aluminum skin on a 737 is about 0.038 inches (or 0.1cm) thick.&lt;br&gt;&#xA;We know a window on a 737 is thicker than the skin. I couldn't find the number but let's go with 0.25&quot; (0.6cm).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we have a hypothetical one-foot square window (about 930 cm&lt;sup&gt;2&lt;/sup&gt;), the aluminum skin occupying that area would weigh about 251 grams. The Plexiglass equivalent would weigh about 658 grams (407 grams heavier, little more than 2.5 times as heavy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure there are about 70 side windows on a 737 (quick count from a photo of a Southwest plane, not including exit door windows), so that's 28,490 grams or about 64 pounds, just for the plexiglass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the plexiglass there's also supporting structure that needs to be added around the window to hold it in place, sealants to seal it against the skin, etc. - these add additional weight. I've no idea what these components weigh, but let's assume it weighs twice as much as the plexiglass, that's about 1.5 pounds per window of additional structure, or 105 pounds, bringing the total weight savings to just under 170 pounds.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;170 pounds is not a lot of weight (in passenger terms it's not even one person), but it is that much more cargo you can carry. Also when combined with the fact that you no longer have to maintain the windows (fix pressure leaks in the seals, replace cracked plexiglass, etc.) the savings can add up over the life of an airframe.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some more spitballing here... please feel free to correct my numbers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the subject of the cost savings: a 737 can carry about 27000 lbs payload, and burns about 5500 lbs of fuel / hour during cruise, and about 3000 lbs for a 15 minute climb. Assuming an average flight of 4 hours you get about 25000 lbs of fuel burnt, or almost 1 per pound of weight. This means that the fuel cost of 170 pounds of weight is about 170 pounds of fuel, which today costs (at around \$4 / gallon, and 6.5 lbs/gallon) around \$100.  Note that the cost of fuel varies a lot with location, so this is very approximate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now multiply this by the typical life of the aircraft - three flights per day, 7 days per week, for 30 years? That would be over \$3M of savings. And all because your parcels can't look out of the window.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="31540" LastEditDate="2018-06-08T18:08:14.730" LastActivityDate="2018-06-08T18:08:14.730" CommentCount="13" CommunityOwnedDate="2015-02-03T20:08:48.157" ContentLicense="CC BY-SA 4.0" />
  <row Id="12361" PostTypeId="2" ParentId="12356" CreationDate="2015-02-03T20:13:01.560" Score="55" Body="&lt;p&gt;Why do airliners have them? Because passengers like them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you're sitting in the penalty box waiting for a departure slot and the air conditioning system is barely running the extra cool air you can get from those vents may be the only thing keeping passengers from strangling the screaming child kicking the seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also a common &quot;cure&quot; for airsickness is fresh air -- blowing cool air over someone's face will often help with symptoms of motion sickness, and may prevent a nauseous passenger from actually vomiting. Opening these overhead &quot;gasper vents&quot; and directing them at the passenger's face provides a quick way of doing this.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-03T20:13:01.560" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12362" PostTypeId="2" ParentId="12359" CreationDate="2015-02-03T21:25:29.690" Score="18" Body="&lt;p&gt;The additional mass due to windows can best be estimated by statistical methods. By comparing the structural mass of windowed and window-less fuselages of otherwise identical aircraft and formulating a numerical equation which fits all cases with the least error, you get formulas like&#xA;$$n_{Windows}\cdot 4.641\cdot S_{Window}^{0.976}\cdot(1.0 + \Delta p)^{4.945}$$&#xA;where $n_{Windows}$ is the number of windows, $S_{Window}$ is their surface area in m² and $\Delta p$ is the pressure differential of the pressurized fuselage in bar. The resulting mass is in Kilos (kg). This formula is from the LTH (Luftfahrttechnisches Handbuch) and based on 16 aircraft. Standard deviation is 20.3%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual values per window are between 3.5 kg in case of the DC-10-10 and more than 7 kg in case of the Boeing 747-200. Sorry, I have no data for the XL-sized windows of the Boeing 787. If we assume 80 windows in total for a Boeing 737-class aircraft, the total mass of the windows is about 300 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jan Roskam cites a different formula (called the GD method, originally from General Dynamics). Here window mass is&#xA;$$109\cdot(n_{pax}\cdot\frac{1+\Delta p}{100})^{0.505}$$&#xA;Now the pressure differential is in psi, the result in pounds and for an aircraft with $n_{pax}$ = 150 passengers the value is 437 lbs or 198 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The window mass takes account not only of the transparent material, but also of the local reinforcement of the fuselage skin. Either doublers are riveted around the window hole, or the whole skin is chemically etched to reduce its thickness, and the area around the window is masked to keep the original thickness. As a rule of thumb, you should add around the circumference what you take away by cutting the hole. Thus, a well-designed fuselage should have a net mass increase roughly equivalent to the mass of the windows themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Roskam formula is older, and window size and mass have increased over the last decades. Therefore, the newer the aircraft, the heavier its windows.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-08-16T00:59:40.793" LastActivityDate="2016-08-16T00:59:40.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12363" PostTypeId="2" ParentId="12352" CreationDate="2015-02-03T21:30:35.463" Score="-1" Body="&lt;p&gt;I assume you are specifically asking about increase in lift.  There are a lot of other constraints and problems that come into play when designing an airfoil, but here is the short answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind the main limiting factor is going to be the drag on the airfoil.  There are two primary kinds of drag: form drag and surface drag.  Form drag is the drag caused by the area and shape of an object moving through the air - think of this as holding your hand out the window of your car with the palm facing forward.  The other kind of drag is surface drag, this is the drag caused by the surface area parallel to the airflow - think of this as holding your hand out the window with your thumb forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is proportional to surface area of the airfoil.  Increasing the size of the airfoil is going to increase the surface drag regardless of weather you increase the length or width.  However, increasing the length of an airfoil is going to introduce more form drag, while increasing the chord is &quot;only&quot; going to increase the surface drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the short answer to your question is: increasing the chord is more efficient than increasing the length.  However, there is obviously a lot more at play, or else helo rotors would be short and stubby!&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2015-02-03T21:30:35.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12364" PostTypeId="1" CreationDate="2015-02-03T21:38:32.510" Score="5" ViewCount="1952" Body="&lt;p&gt;For someone that has recently completed their private pilot SEL, what would be the suggested next steps/process to getting instrument rated as efficiently as possible (both time and money)? &lt;/p&gt;&#xA;" OwnerUserId="7029" LastActivityDate="2016-03-14T23:21:36.180" Title="What is the most efficient way to get your instrument rating?" Tags="&lt;flight-training&gt;&lt;instrument-flight-rules&gt;&lt;single-engine&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12365" PostTypeId="1" AcceptedAnswerId="12372" CreationDate="2015-02-03T21:47:06.113" Score="33" ViewCount="9294" Body="&lt;p&gt;I'm talking about this sort of thing (this is the fictional airplane from &lt;em&gt;Casino Royale&lt;/em&gt;), rather than two (or more) engines per wing in individual nacelles:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0e7Gs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we ignore the weird 'drop tanks' on the outer pylons, what makes this design inferior to one with individual nacelles? I can think of some highly speculative pros and cons for both layouts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pros for shared nacelles:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Shared nacelle and pylon potentially means less frontal and wetted area per engine, which could maybe reduce overall drag.&lt;/li&gt;&#xA;&lt;li&gt;Overall, this scheme seems to allow the 'center of thrust' for all the engines on one wing to come closer to the centerline of the aircraft. In some designs like the A380, where a &lt;em&gt;massive&lt;/em&gt; vertical fin is needed to maintain yaw authority in an engine(s)-out situation, it seems like this could save quite a bit of weight and drag by reducing the size of the vertical fin.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cons for shared nacelles:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obviously there is an increased risk that an uncontained engine failure like the one on an A380 a few years ago could cause cascading failures in its 'neighbor'. I'm not sure how to quantify this risk, but it seems significant.&lt;/li&gt;&#xA;&lt;li&gt;Additionally, a structural failure in a pylon/nacelle (extremely rare but it does happen IIRC) will affect two engines instead of one.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance will be probably be more difficult, since you'll have to mess with two engines just to get at one.&lt;/li&gt;&#xA;&lt;li&gt;I'd expect that due to the structural requirements of supporting two engines on one pylon, you probably wouldn't save much weight and you might actually end up with a heavier aircraft, all other things being equal.&lt;/li&gt;&#xA;&lt;li&gt;Maybe you'd lose some efficiency in the interaction between the exhausts of both engines in a nacelle?&lt;/li&gt;&#xA;&lt;li&gt;It might turn out that you can't fit two large high-bypass turbofans into one nacelle without choosing between flow separation issues and greatly increased frontal area.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is all layman speculation, though. In reality, from an engineer's point of view, is the choice of one layout over the other obvious? Why or why not?&lt;/p&gt;&#xA;" OwnerUserId="7145" LastActivityDate="2018-01-28T07:39:17.187" Title="Why do we never see high-bypass turbofan engines sharing the same nacelle on large airliners and similar aircraft?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;engine&gt;&lt;multi-engine&gt;" AnswerCount="6" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12366" PostTypeId="2" ParentId="12364" CreationDate="2015-02-03T21:58:01.073" Score="8" Body="&lt;p&gt;The fastest path to &lt;em&gt;any&lt;/em&gt; rating is intensive training.&lt;br&gt;&#xA;If you can take time off from work and do &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2000/August/200008_Features_Eight_Days_To_Instruments.html&quot;&gt;an &quot;accelerated instrument training&quot; program&lt;/a&gt; you can probably knock out the rating in less than a month. That AOPA article says 8 days, I've seen a lot of &lt;a href=&quot;https://www.google.com/search?q=Two+week+instrument+rating&quot;&gt;two-week courses&lt;/a&gt; advertised.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note however that there's a difference between being &lt;em&gt;instrument rated&lt;/em&gt; and &lt;em&gt;proficient for real-world IFR operations in actual IMC&lt;/em&gt;. These courses will almost certainly cram all the knowledge and procedures into your head that are required to get you to pass your instrument checkride, but you may have never flown an approach in actual IMC (if suitable weather doesn't pop up for you to fly in your time will all be simulated under the hood), and because everything is compressed and focused on &quot;passing the test&quot; you may come out of the program lacking the confidence to actually go out and &lt;em&gt;use&lt;/em&gt; your newfound rating without doing some additional work with a local CFI (this is a point sometimes raised by pilots who have gone through these accelerated training programs).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-03T21:58:01.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12367" PostTypeId="1" CreationDate="2015-02-03T22:00:48.540" Score="1" ViewCount="800" Body="&lt;p&gt;In regards to air traffic control, FAA Order 7110.65 is the standard for policy and procedure in the USA. Do other countries use this also? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an 'international standard' for air traffic control? If so, are there any notable differences between that and the service provided by U.S. FAA?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="572" LastEditDate="2015-02-19T08:41:19.967" LastActivityDate="2015-02-19T08:41:19.967" Title="Are there international standards to Air Traffic Control procedures similar to US standands?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;usa&gt;&lt;faa&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12368" PostTypeId="2" ParentId="12365" CreationDate="2015-02-03T22:06:35.490" Score="14" Body="&lt;p&gt;A big part of this is probably related to maintenance, as you observed. Currently, engines are generally taken straight off of the pylon. If they were paired on a pylon, They would either have to be removed together (making them essentially half as reliable) or attached in a different way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With modern jet engines, only the largest aircraft make sense to have 4 engines, because two-engine aircraft are more efficient. This means planes like the 747 and A380 would be candidates for this design. There is actually a structural benefit of placing an engine further out on the wing. When in flight, the weight of the engine helps to relieve the bending moment on the wing. As you observed, this makes engine-out control more difficult. The placement of two engines on a wing is a compromise between structure and engine-out control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would also affect the amount of power the plane needs. Twin-engine aircraft must have enough power to take off if an engine fails after V1. This means that they need to continue a takeoff on 50% power. Aircraft with four engines must meet the same requirement, but this means they need to continue a takeoff with 75% power. However, pairing the engines makes it much more likely that a failure in one will affect the other. This means that the plane may be required to fly on 50% power, which will make the plane even less efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another potential issue is reverse thrust. Currently, engines can use locations around the circumference of the nacelle to eject this air. With the engines combined, each one would only have part of the circumference, so this could create flow issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cases of failed engines or thrust reversers would put torque on the pylon, requiring additional weight for strength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There could be some benefit of combining engine systems, but it would be at the cost of reduced redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would reduce the area of the outside of the nacelle, but increase the frontal area. Considering two 120-inch diameter engines, combining them by connecting straight across on top and bottom, you decrease the perimeter from 750 inches to 615 inches, but you increase the frontal area from 22600 in^2 to 25700 in^2. Bringing the profile in between the engines (like in the photo above), will decrease the frontal area, but also increase the perimeter.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-03T22:22:33.953" LastActivityDate="2015-02-03T22:22:33.953" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12369" PostTypeId="1" AcceptedAnswerId="12371" CreationDate="2015-02-03T22:18:20.380" Score="16" ViewCount="8523" Body="&lt;p&gt;Airbus and Boeing use this special naming scheme for their civilian aircraft models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All Boeings built today are B7x7.&#xA;(In the past, also other numbers were used: the shortened version of a B707, the B727 and even older models like B367, B377 etc. )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, Airbus uses a common scheme: A3x0, though there a few numbers outside this scheme: A318/19/21&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Both manufacturers also build military aircrafts with different schemes, like A400M.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is there a special reason for these naming schemes, or is is just that they sound good and unique?&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="97" LastEditDate="2015-02-04T03:10:16.953" LastActivityDate="2015-02-04T03:10:16.953" Title="Why does Boeing name its aircraft B7x7 and Airbus names theirs A3x0?" Tags="&lt;boeing&gt;&lt;aviation-history&gt;&lt;airbus&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12370" PostTypeId="2" ParentId="12365" CreationDate="2015-02-03T22:18:53.560" Score="4" Body="&lt;p&gt;For an engine to be efficient from a propulsive point of view, there is the need to &quot;move a high quantity of flow with the same energy&quot;. Which means, for a given core create the bigger fan possible. So, from propulsion perspective, that design is less efficient than the A380 like configuration. You can see &lt;a href=&quot;http://en.wikipedia.org/wiki/Propulsive_efficiency&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; more information about propulsive efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no so much saving in wetted area, but there will be some interference between both engines in the exhaust reduction on top the efficiency. Also the junction between both engines will create a grow of boundary layer, making the junction more draggy. I can't quantify the total drag, but is not clear for me that netly the drag saving in wet surface compensates or not the increase in viscous (boundary layer) increase in drag and the propulsion integration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine is basically an aspiration machine which tries to absorb the flow arround the engine, this will be less important at cruise, but at take off both engines will compete for the air around, making them to produce less thrust. Critical engine failure take off is usually a dimensioning condition for engine size... so we have less efficiency in the most critical condition. From a global airplane perspective this makes the engine more overdimensioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your point about the vertical fin is correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning the risk of uncontained engine failure, the engines are usually design to avoid this situation. I do love &lt;a href=&quot;https://www.youtube.com/watch?v=nDrU22R3gg4&amp;amp;list=PLQjqzj7z9ZNFi3rInDJclf5MU_e4YWT2q&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; about the test made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of structure, take into accoutn that in the condition of one engine failure you will need to include yaw momentun of having one engine operationally working and the other not. So very likely the pylon will be heavier that 2 pylons (although less draggy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, this configuration doesn't make any sense, is usually cheaper to include a trim tank than using external, draggy, fuel pods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a example that the trade-off joining engines are not really making the business just look to all blended wings airplanes, all of them are having their engines on the upper part of the airplane separated between them (like &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_X-48&quot; rel=&quot;nofollow&quot;&gt;X48&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As general rule I would say &quot;fewer engines as bigger as possible&quot;.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-02-03T22:18:53.560" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12371" PostTypeId="2" ParentId="12369" CreationDate="2015-02-03T22:47:34.297" Score="14" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus&quot;&gt;Airbus&lt;/a&gt; started with the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A300&quot;&gt;A300&lt;/a&gt;, which as usernumber commented was a 300-seat airliner design. So &lt;em&gt;A&lt;/em&gt; for Airbus, and 300 for the number of seats. An A250 was also considered (guess how many seats), which became the A300B. The models counted up by 10 from there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing model numbers historically counted up, including the Model 40, Model 80, Model 247, Model 307 Stratoliner and Model 377 Stratocruiser. At the dawn of the jet age, they decided to &lt;a href=&quot;http://www.boeing.com/news/frontiers/archive/2004/february/i_history.html&quot;&gt;change up their numbering scheme&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To support this diversification strategy, the engineering department divided the model numbers into blocks of 100 for each of the new product areas: 300s and 400s continued to represent aircraft, 500s would be used on turbine engines, 600s for rockets and missiles and 700s were set aside for jet transport aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The 707 prototype was called the 367-80, or &quot;Dash 80.&quot; When the time came to give it an official number they knew it was going to be a &quot;Jet Transport&quot; and would get a 700-series number, and they decided &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_707&quot;&gt;707&lt;/a&gt;&quot; had a better sound to it than &quot;700&quot;. They kept the 7's and have counted up from there (not entirely in order).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-03T22:51:23.020" LastActivityDate="2015-02-03T22:51:23.020" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12372" PostTypeId="2" ParentId="12365" CreationDate="2015-02-03T22:59:15.927" Score="34" Body="&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It's the vastly different flow conditions from static to cruise which demand a separate placing of high-bypass-ratio jet engines. They would produce less thrust and more drag when paired.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why were there paired engines at all?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The early jets had their engines mounted directly beneath or in the wing, and comparisons between separately mounted and twinned engines showed a slight advantage for the latter due to lower wetted surface area and less impact on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arado built two four-engined prototypes of their &lt;a href=&quot;http://en.wikipedia.org/wiki/Arado_Ar_234&quot; rel=&quot;noreferrer&quot;&gt;Ar-234&lt;/a&gt; jet, one with separate engines (V6, see directly below) and one with paired engines (V8, further down). The V8 became the prototype of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Arado_Ar_234#Ar_234C&quot; rel=&quot;noreferrer&quot;&gt;C version&lt;/a&gt; of the Ar-234.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7l3im.jpg&quot; alt=&quot;Arado 234 V6&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/y9yop.jpg&quot; alt=&quot;Arado 234 V8&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, with the increasing airflow of high-bypass-ratio engines the interference between both will turn pairing into a disadvantage. In cruise, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;only the central stream tube flowing towards the engine will be ingested&lt;/a&gt;, and the rest will spill over the intake lip. Placing a second engine directly next to the first will block the flow of spilled air on that side and will increase spill flow on the opposite side. This will most likely cause massive separation there if the intake is not &lt;a href=&quot;https://aviation.stackexchange.com/questions/47976/why-does-the-b-52-outboard-engine-nacelle-have-a-sharp-change-in-shape/48036#48036&quot;&gt;heavily modified&lt;/a&gt;, leading to a noticeable drag increase. Also, the now asymmetric flow in the intake would reduce the efficiency of the fan - it needs very homogenous flow over the full cross section in today's engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, at low speed the engine &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;sucks in air from all around&lt;/a&gt; and will face competition from a second engine, such that both will not be able to ingest as much air as when mounted separately. The consequence of pairing would be reduced thrust during take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial disadvantage of separate engines, their collective impact on wing aerodynamics, is now greatly reduced by &lt;a href=&quot;https://aviation.stackexchange.com/questions/12109/why-do-we-use-pylons-to-mount-engine-on-jet-airliners&quot;&gt;mounting them on pylons&lt;/a&gt;, so they are ahead and below the wing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-01-28T07:39:17.187" LastActivityDate="2018-01-28T07:39:17.187" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12373" PostTypeId="2" ParentId="12364" CreationDate="2015-02-04T03:15:45.370" Score="-1" Body="&lt;p&gt;Well for money, the military is the most efficient.  For time, just getting it done as fast as possible (one of those 10 week/summer programs) and showing up to each lesson prepared.  For being extremely confident in IMC flying, again, the military.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-04T03:15:45.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12374" PostTypeId="2" ParentId="12149" CreationDate="2015-02-04T03:20:32.333" Score="1" Body="&lt;p&gt;One thing I haven't seen mentioned is putting some G on the aircraft.  Most people never think of it, but increasing the G load on a jet slows it down incredibly fast.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-04T03:20:32.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12375" PostTypeId="1" CreationDate="2015-02-04T03:25:56.277" Score="10" ViewCount="1788" Body="&lt;p&gt;Wikipedia lists the &lt;a href=&quot;http://en.wikipedia.org/wiki/World%27s_busiest_passenger_air_routes&quot; rel=&quot;noreferrer&quot;&gt;busiest &lt;strong&gt;city to city&lt;/strong&gt; routes&lt;/a&gt;.  But for instance (&lt;em&gt;nb: this is purely speculation&lt;/em&gt;), flights originating in Boston would transit through much of the same airspace to get to LA as a slightly shorter flight originating out of DC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;s&gt;What are the busiest actual air routes (&lt;a href=&quot;http://en.wikipedia.org/wiki/Airway_%28aviation%29&quot; rel=&quot;noreferrer&quot;&gt;airways&lt;/a&gt;) (irrespective of origin/destination cities)?  Total aircraft count, as well as passenger- and cargo-based metrics appreciated.&lt;/s&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a breakdown of aircraft volume transiting between and within the 22 area control centers in the United States?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best map I've found so far came from &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/us_eu_comparison_2013.pdf&quot; rel=&quot;noreferrer&quot;&gt;this joint publication&lt;/a&gt; comparing the US and EU in air traffic management, but this does not show traffic flow between areas:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AKm3t.png&quot; alt=&quot;Air Traffic Density&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As originally phrased, I realize such a graph could get very much &quot;into the weeds&quot;.  I'm rephrasing the question to start high-level and then work down (if possible).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, a flight from Tucson to LA involves a handoff from ZAB to ZLA, such that a numerical representation (aka directed graph) might look like this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;        In  &#xA;        ZLA ZAB&#xA;Out ZLA  X   X&#xA;    ZAB  1   X&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Adding flights from Tucson to Phoenix (within the same ARTCC) and from LA to Tucson would result in this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;        In  &#xA;        ZLA ZAB&#xA;Out ZLA  X  *1*&#xA;    ZAB  1  *1*&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Ultimately, this matrix would be 22x22, but since not all ARTCCs can handoff to all others, many cells would be zero.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-02-05T06:00:34.803" LastActivityDate="2015-12-16T13:08:50.980" Title="What are the busiest airways?" Tags="&lt;air-traffic-control&gt;&lt;flight-path&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12377" PostTypeId="1" AcceptedAnswerId="12378" CreationDate="2015-02-04T05:28:14.757" Score="8" ViewCount="1518" Body="&lt;p&gt;I've recently started taking flying lessons and was wondering if I should begin logging my flying hours immediately?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware there are minimum hours for each license certification, so I'm assuming I should be noting down my flight time right from the start but my instructor hasn't really said anything about it yet.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="65" LastEditDate="2015-02-04T18:32:55.077" LastActivityDate="2015-02-05T18:01:05.163" Title="Should I log flying lessons from the start?" Tags="&lt;logging&gt;&lt;student-pilot&gt;&lt;logbook-endorsements&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12378" PostTypeId="2" ParentId="12377" CreationDate="2015-02-04T05:29:56.210" Score="15" Body="&lt;p&gt;Yes, you should be logging from the start. Now for the first few lessons, it'd be ok to not have your own logbook yet, but you should get one. Hopefully your instructor has kept his up to date, and can build your logbook in terms of flight times since you started.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-02-04T05:29:56.210" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12381" PostTypeId="2" ParentId="12352" CreationDate="2015-02-04T06:57:50.967" Score="13" Body="&lt;p&gt;It's not so easy. The blade length, chord and engine power are connected in complex ways, and for each desired performance there is an optimal combination of those parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotors (and wings) generate lift by accelerating air downwards. The lift is proportional to the rate of change of inertia of the air. This, however, also changes kinetic energy of the air and therefore requires power. This is called induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since inertia is proportional to velocity, but kinetic energy is proportional to the square of velocity, it is more efficient to accelerate a larger amount of air to a lower speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of air affected is proportional to the area of the &lt;em&gt;rotor disk&lt;/em&gt; (the whole area in which the blades move) and that is simply ($\pi\times$) square of blade length. So in a sense the answer is easy: only blade length has effect, blade chord does not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, increasing the blade length also increases the form and skin drag of the blades, so beyond some point the form drag will exceed the induced drag and any additional increase in blade length won't improve efficiency further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even more importantly, a longer blade will be heavier and therefore will have to be stronger to withstand the centrifugal force when turning, and stiffer so it does not bend too much when not. But that will make it even heavier and you'll reach a point where you simply exceed the capabilities of the material. And of course higher weight also means more lift is required. These effects will further reduce the optimal length of the blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blade chord is then a secondary parameter governed by two concerns: the chord has to be long enough so the blades can generate the necessary lift without stalling and they have to be strong enough, strength being proportional to chord times thickness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you want to improve load, you can try to improve efficiency, which you could do by making the blades longer, but you need to find a material with higher specific strength, otherwise the increased weight will outweigh the improved aerodynamic efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't have that, you will primarily have to increase power of the engines. The optimal blade length may then be longer too, but you will be hitting the limits of the material quickly; that's why there are multi-rotor helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you instead meant speed, that's a completely different issue and neither blade length nor chord play a significant role there. In forward motion, the speed of a helicopter is limited by two constraints: sufficient portion of the retreating blade has to move aft relative to the airflow and the tip of advancing blade must not exceed speed of sound (actually, critical Mach number, which is somewhat lower). The first requirement means the tip speed must be around three times higher than the maximum forward speed, otherwise the retreating side of the rotor won't be able to generate enough lift and the aircraft will roll to that side. Together with the second parameter, it limits the speed to about a quarter of the critical Mach. There are some experimental twin rotor (intermeshing, side-by-side) helicopters that don't mind the lift asymmetry and can fly somewhat faster. But it has nothing to do with blade length; blades of larger rotor spin at lower rpm to maintain similar tip speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="755" LastEditDate="2017-05-19T04:51:53.867" LastActivityDate="2017-05-19T04:51:53.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12383" PostTypeId="1" AcceptedAnswerId="12386" CreationDate="2015-02-04T09:07:49.210" Score="31" ViewCount="16799" Body="&lt;p&gt;I've seen &lt;a href=&quot;https://aviation.stackexchange.com/questions/1152/if-the-profile-of-a-wing-pulls-a-plane-up-why-can-planes-fly-inverted&quot;&gt;this answer&lt;/a&gt; to the question about flying upside-down, but tilted by 90°, there should be no surface creating lift (except maybe the vertical stabilizer).&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-07-02T05:10:34.790" Title="Can you fly an airplane at a 90° roll angle without losing altitude?" Tags="&lt;aerodynamics&gt;&lt;aerobatics&gt;" AnswerCount="7" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12385" PostTypeId="2" ParentId="12383" CreationDate="2015-02-04T09:31:03.373" Score="14" Body="&lt;p&gt;Regular airplanes, no. They depend on lift produced by the wings and fuselage to stay airborne. No aircraft that I know of can produce enough lift with its component tilted 90°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all assumes 'normal' airplanes though. If you have enough thrust, there's nothing that says you need to depend on wings for lift, and if your thrust is vectored at least a little downwards producing enough of a vertical component to keep you from descending, it won't matter which direction anything else is pointing. The extreme example of this is of course space rockets.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-02-04T22:21:06.820" LastActivityDate="2015-02-04T22:21:06.820" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12386" PostTypeId="2" ParentId="12383" CreationDate="2015-02-04T10:38:19.370" Score="62" Body="&lt;p&gt;It depends. As always. If thrust is high enough, why not?&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://flighttraining.aopa.org/magazine/1998/August/199808_Training_Topics_Form_and_Function.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Knife edge flight&lt;/a&gt; is a regular part of aerobatic performances, and the fuselage is producing &lt;em&gt;almost&lt;/em&gt;* all the needed lift. This requires&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Enough speed,&lt;/li&gt;&#xA;&lt;li&gt;A low ratio of aircraft mass to fuselage side area, and&lt;/li&gt;&#xA;&lt;li&gt;Enough rudder deflection to trim the aircraft in a sufficiently high sidelip angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;For horizontal flight your installed thrust must be sufficient to compensate for the high drag in this attitude. This should be no problem with powerful propeller aircraft if their fuel system keeps them supplied at this attitude. Jets must make sure that the sideslip angle can be tolerated by the intake.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/27SuC.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The smoke from the exhaust indicates that this biplane flies horizontally. Yes, it is a large model airplane (not man-carrying, but almost big enough for that). But the laws of physics don't change with scale. For an example of a full-size aircraft doing a knife edge, see &lt;a href=&quot;https://www.youtube.com/watch?v=4CT-pIUjGZE&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt;. Thanks go to @romkyns for pointing this out to me!&lt;/p&gt;&#xA;&lt;p&gt;Note the rudder deflection to keep it at this angle of sideslip. Direction is controlled with the elevator. At this rate of sideslip the propeller thrust contributes to overall lift as well, however, the vertical adds a substantial downforce in order to trim the aircraft and the fuselage has to supply the remaining lift.&lt;/p&gt;&#xA;&lt;p&gt;* Almost means that the propeller will carry some of the weight, but the large downforce on the vertical needs to be compensated, too. In sum, the lift contributed by the fuselage is very close to the weight of the plane.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-07-02T05:10:34.790" LastActivityDate="2020-07-02T05:10:34.790" CommentCount="13" ContentLicense="CC BY-SA 4.0" />
  <row Id="12387" PostTypeId="2" ParentId="12383" CreationDate="2015-02-04T10:43:02.223" Score="10" Body="&lt;p&gt;This happens (for several seconds at a time) as part of the &quot;hesitation roll&quot; aerobatic maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on the fuselage alone for lift (in excess of the vertical component of thrust), so the nose has to point into the sky and the rudder is used to maintain that attitude. Because fuselages have rather dismal L/D it will require sufficient thrust, or bleed off a lot of speed.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-02-05T16:39:22.750" LastActivityDate="2015-02-05T16:39:22.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12389" PostTypeId="2" ParentId="12377" CreationDate="2015-02-04T14:22:56.983" Score="2" Body="&lt;p&gt;Yes you should whether you are PIC or not, solo or dual.&lt;/p&gt;&#xA;" OwnerUserId="7157" LastActivityDate="2015-02-04T14:22:56.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12390" PostTypeId="1" CreationDate="2015-02-04T14:25:03.007" Score="6" ViewCount="1394" Body="&lt;p&gt;The &lt;a href=&quot;http://www.risingup.com/fars/info/part91-108-SFAR.shtml&quot;&gt;Mitsubishi MU-2B has a very long &amp;amp; detailed SFAR 108&lt;/a&gt; that details the trained and currency requirements for anyone who wishes to manipulate the controls of the plane. I'm wondering what incidents or accidents and unusual handling characteristics required a Special SFR for this plane.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="22726" LastEditDate="2019-07-03T21:51:33.937" LastActivityDate="2019-07-03T21:51:33.937" Title="Why does the Mitsubishi MU–2B have its own SFAR?" Tags="&lt;faa-regulations&gt;&lt;aerodynamics&gt;&lt;emergency&gt;&lt;mitsubishi-mu-2&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12391" PostTypeId="2" ParentId="12390" CreationDate="2015-02-04T15:59:43.310" Score="2" Body="&lt;p&gt;According to Wikipedia (or at least my reading of the article) &lt;a href=&quot;http://en.wikipedia.org/wiki/Mitsubishi_MU-2&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Mitsubishi_MU-2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like there were a lot of incidents in the plane, enough that the FAA seems to have investigated the plane specifically and now advises/requires some special training for it. As any government agency would they also issued lots of paperwork as a result thus your findings. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-02-04T15:59:43.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12393" PostTypeId="2" ParentId="12377" CreationDate="2015-02-04T16:23:20.240" Score="3" Body="&lt;p&gt;As has been mentioned you should log hours as soon as you start flying. All training hours with a CFI count towards your license, if you are paying for those lessons, you should log them. As for books, also as mentioned there are a few kinds out there but if you are starting with your PPL a basic log book will suffice. There are also many paid, online services that come in the form of tablet/smartphone apps that are now FAA accepted as official logs (and your instructor an even sign them digitally). This is a nice solution as you don't have to worry about your data getting lost. I will personally be moving to this soon (when I start my instrument training). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: if you have an iPad or iPhone there are lots of cool flight apps out there that are now legal replacements for paper maps, although you should still carry a paper or second digital back up.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-02-04T18:29:11.553" LastActivityDate="2015-02-04T18:29:11.553" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12394" PostTypeId="2" ParentId="12356" CreationDate="2015-02-04T16:37:47.090" Score="5" Body="&lt;p&gt;The primary reason is that not everyone likes the same temperatures. I happen to be cold-natured and like to be warm. Other people are hot-natured and like to use copious amounts of air conditioning. These allow all of us to stay relatively comfortable in the same cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when you're sitting on the ramp in the summer, it's more than 100 degrees Farenheit outside, and the boarding door is still open, you'll learn to appreciate these things quickly, especially if you've been standing in the jetway a while before taking your seat. Personally, I usually turn mine off during flight, but I do tend to use them on the ramp and sometimes during taxi in the summer and/or unusually hot climates.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-02-04T16:37:47.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12395" PostTypeId="1" CreationDate="2015-02-04T16:41:41.460" Score="4" ViewCount="1134" Body="&lt;p&gt;CNN &lt;a href=&quot;http://transcripts.cnn.com/TRANSCRIPTS/1412/30/nday.05.html&quot; rel=&quot;nofollow&quot;&gt;reported&lt;/a&gt; that the cause the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/Indonesia_AirAsia_Flight_8501&quot; rel=&quot;nofollow&quot;&gt;AirAsia Flight 8501&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... it stalled and fell out of the sky ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The reality is that when an airplane stalls it &lt;strong&gt;does not&lt;/strong&gt; fall out of the sky. Why did CNN report such a statement?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft was at 36,000 feet when it stalled. According to the flight recorder, it was descending at 6000 feet per minute. Stalling an airplane at 36,000 feet means there is plenty of time to recover from any stall, unless the airplane was loaded tail heavy. But that was not reported.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I missing something here?  &lt;/p&gt;&#xA;" OwnerUserId="7162" LastEditorUserId="65" LastEditDate="2015-02-04T17:12:17.227" LastActivityDate="2015-02-05T00:14:12.913" Title="Did CNN correctly state that AirAsia flight stalled and crashed?" Tags="&lt;accidents&gt;&lt;stall&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="2" ClosedDate="2015-02-05T01:48:15.253" ContentLicense="CC BY-SA 3.0" />
  <row Id="12396" PostTypeId="2" ParentId="12199" CreationDate="2015-02-04T16:47:42.267" Score="2" Body="&lt;p&gt;No you don't &quot;need&quot; them but I would strongly advise them for a few reasons, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UV Protection&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not only do the front windshields of GA planes provide little UV protection you are flying at altitude and the higher you go the less natural UV protection you will get. Granted the change may me minimal it is still present. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Comfort&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long exposure to bright sunlight can cause the eyes to tire out which can make it harder to see. You can actually get sun burn on your retina if you are exposed directly for to long. The last thing you want to happen when you are flying is to impair your vision in any way or simply get fatigued. That is when you start to make mistakes in a plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Looks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who doesn't look great in aviators...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Some Advice&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also wear glasses regularly for distance (like your friend). When I started flying it was actually cheaper (or about even) to get fit for contacts and buy a nice pair of aviators than it was to get prescription sunglasses cut. I now don't have to worry about my sun glass prescription having to be cut or losing a very expensive pair of prescription sunglasses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned I would NOT get polarized sun glasses because of the issues with glass cockpits. I have a pair of Ray-Ban aviators with the G15 (non polarized) glass and they are great. That being said I would also opt for more function over style here. Don't get half fade lenses or any of that stuff either it may look cooler but it wont provide any sun protection on the bottom half of the lens. You want something that provides good protection but still allows a good amount of light in as you will still have to read the instruments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;G15 is the traditional green glass that Ray-Ban uses in their sunglasses. It provides good protection with out the need for polarization. I suggested it because I also had a pair of the half fade Ray-Bans that I tried to fly with when I first started and they were terrible. They simply did not block enough light to be as effective as I wanted/needed them to be. The G15 provides a good amount of coverage with out using polarization and thus without interfering with glass cockpits if you happen to end up in that kind of plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know how long you need to be exposed to get permanent eye damage but I tend to not play around with these kinds of issues, especially if it will permanently hamper my ability to fly. A decent pair of sun glasses be it Ray-Bans or any other of the popular brands may run you $100-$150 which pales in comparison to what you will spend getting your PPL.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-02-06T17:04:29.630" LastActivityDate="2015-02-06T17:04:29.630" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12397" PostTypeId="2" ParentId="12395" CreationDate="2015-02-04T16:56:53.520" Score="12" Body="&lt;p&gt;An aerodynamic stall is exactly that: the wing is stalled and is not generating enough lift to keep the aircraft in the sky. The aircraft &lt;strong&gt;is&lt;/strong&gt; falling out of the sky. Whether the stall can be recovered from, and therefore the aircraft can &lt;em&gt;stop&lt;/em&gt; falling out of the sky, is an entirely different question.&lt;/p&gt;&#xA;&lt;p&gt;Some stalls can be recovered from, others cannot... particularly if whatever caused the stall is preventing recovery.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;An aerodynamic surface which is &lt;strong&gt;stalled&lt;/strong&gt; is no longer generating significant lift. Most specifically it's not generating enough lift to support the aircraft&lt;/p&gt;&#xA;&lt;p&gt;An object which is not generating sufficient lift to keep it airborne, and is being pulled towards the earth by gravity, is &lt;strong&gt;falling&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So yes, CNN is correct - the plane fell out of the sky while stalled. Generally a plane which is at 36,000 ft and is &lt;strong&gt;not&lt;/strong&gt; falling out of the sky, doesn't hit the ground.&lt;/p&gt;&#xA;&lt;p&gt;As Falstro mentioned in his comment, AF447 didn't realise it was in a stall at all, so therefore couldn't remove it. We don't really have enough information about the AirAsia flight to be sure what happened&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-05T00:14:12.913" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12398" PostTypeId="2" ParentId="12356" CreationDate="2015-02-04T17:23:15.673" Score="1" Body="&lt;p&gt;Although probably not the primary reason airlines have them in the first place, there is another great reason to use them.  Having fresh &quot;outside&quot; air blow in front of you displaces the viruses/bacteria/etc. from sick passenger's coughs and sneezes away from entering your nose and mouth.&lt;/p&gt;&#xA;" OwnerUserId="7163" LastActivityDate="2015-02-04T17:23:15.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12399" PostTypeId="2" ParentId="12383" CreationDate="2015-02-04T17:29:27.937" Score="3" Body="&lt;p&gt;We do that all the time with our radio-controlled airplanes. It's called a knife-edge maneuver. Maintaining altitude is easy provided you have enough power and rudder surface area, but maintaining a straight line (with elevator) is usually very tough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not every radio-controlled aircraft can do it though. Usually the planes with small rudder deflection cannot hold altitude if their surface area is small. Aerobatic ones can do it all day along. In fact, an elegant way of coming out of this maneuver is to climb up at the end in that same orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this maneuver the nose of the airplane will always be a little higher (hence in a pitch up attitude) than the tail. I don't see anyone doing it without pitch up and still maintaining the altitude.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="849" LastEditDate="2015-02-04T22:48:08.423" LastActivityDate="2015-02-04T22:48:08.423" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12400" PostTypeId="2" ParentId="12390" CreationDate="2015-02-04T17:33:54.990" Score="0" Body="&lt;p&gt;The MU-2 has had a very bad safety record. From various sources I've talked with over the years, if you lose an engine, you need an excessive amount of altitude to recover. Various design issues I've heard are related to it, from possibly overpowered engines, to short wings. All these things coupled basically put the FAA to put in a Special rules for anyone wanting to fly the MU2. Same with the other SFARs, there's usually been a rash of incidents outside of what's normally taught for the category/class, that requires special or additional training.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-02-04T17:33:54.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12401" PostTypeId="1" AcceptedAnswerId="12402" CreationDate="2015-02-04T17:38:28.673" Score="21" ViewCount="14500" Body="&lt;p&gt;The FAA controls just about everything about civilian aircraft in US airspace in terms of regulation, certification, flight rules, etc. Do they have any authority over military aircraft beyond requiring military flights to communicate with ATC for safety and designating certain areas as military airspace?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9411/can-civilians-fly-military-aircraft&quot;&gt;This question&lt;/a&gt; addresses retired military aircraft in civilian use, and one of the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12227/what-are-the-regulatory-categories-of-aircraft-defined-by-the-faa&quot;&gt;this question&lt;/a&gt; mentions a &quot;Surplus military&quot; category, but nothing about active military.  I'm asking about current, active military aircraft in terms of certification, pilot licensing/qualification, etc.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-11-23T16:10:13.697" Title="How much jurisdiction does the FAA have over military aircraft?" Tags="&lt;faa-regulations&gt;&lt;military&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12402" PostTypeId="2" ParentId="12401" CreationDate="2015-02-04T18:14:11.030" Score="22" Body="&lt;p&gt;If they are being operated by the military, not much. Military operations can exempt themselves from the FARs (as a matter of practice they &lt;em&gt;don't&lt;/em&gt;: When operating in the US National Airspace System they follow the same operational regulations we do, but as a matter of regulation they're subject to the military's rules for airworthiness, maintenance, etc.).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military pilots have a military pilot's license (which can be converted to an FAA license with a little paperwork), and the airworthiness and maintenance standards for active military aircraft are defined and managed by the branch of the service responsible for the aircraft. (This is similar to, but legislatively distinct from, &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1023366&quot;&gt;Public Aircraft Operations&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't mean the FAA is completely silent about military operations/aircraft: There is &lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/16574&quot;&gt;guidance for military aircraft that are based on commercial designs&lt;/a&gt; (also available in an easier-to-read &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/391918&quot;&gt;Advisory Circular: AC 20-169&lt;/a&gt;), which would be applicable to aircraft like the VC-25 (&quot;Air Force One&quot;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-04T18:14:11.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12403" PostTypeId="2" ParentId="12401" CreationDate="2015-02-04T18:15:18.177" Score="13" Body="&lt;p&gt;As mentioned &lt;a href=&quot;http://www.faa.gov/about/mission/activities/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://www.faa.gov/about/safety_efficiency/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, FAA's responsibilities include:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Developing and operating a system of air traffic control and&#xA;  navigation for both civil and military aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, FAA does not govern military aircraft. The military has their own rules and regulations, but the military follows FAA regulations when flying in &lt;a href=&quot;http://en.wikipedia.org/wiki/National_Airspace_System&quot; rel=&quot;noreferrer&quot;&gt;National Airspace&lt;/a&gt;. There is airspace in the US and elsewhere that is set aside for military operations such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Barry_M._Goldwater_Air_Force_Range&quot; rel=&quot;noreferrer&quot;&gt;Barry Goldwater Gunnery Range&lt;/a&gt;. Military jets can fire at targets on the ground and civilian aircraft are kept out. There are many others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As needed, FAA does make special allowances for the military. Below is an example of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Military_operations_area&quot; rel=&quot;noreferrer&quot;&gt;Military operations area&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oLlan.jpg&quot; alt=&quot;MOA&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-02-04T19:18:20.023" LastActivityDate="2015-02-04T19:18:20.023" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12405" PostTypeId="2" ParentId="12134" CreationDate="2015-02-04T19:44:00.837" Score="3" Body="&lt;p&gt;Although I have no specific information on this I do work around electronics/computer for a living so if I had to guess...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The older units most likely ran on slow speed audio tapes of some sort, the quality is not great but you can get a lot of time on a single tape. I don't know how the old ones stored flight data or if they even did but tape format would be an option for that as well.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern ones most likely store data in solid state chips or on a platter style hard drive. I would think solid state non volatile memory is used (think SD memory card) as its far less susceptible to shock damage than a platter style hard drive. Since these devices most likely use components made for generic purposes the audio could be encoded at any variety of resolutions but is most likely 44.1Khz/16bit or something like that simply because thats what many A/D converters run at. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight data may have some custom data format but is stored in some normalized way like any data set on any computer. Maybe JSON, maybe XLM who knows, but things like GPS data have standard string representations that I would think are used. I would think they use some kind of sequential writing on the memory chip so that if something goes wrong mid memory write they can extract based on specific memory locations. Basically if you know that every write of data takes 1000 bytes and you started writing at address 0 you can grab the data from any point in time by directly addressing the memory location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least thats how I would design a black box...      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-02-04T19:44:00.837" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12406" PostTypeId="2" ParentId="12390" CreationDate="2015-02-04T20:02:50.247" Score="5" Body="&lt;p&gt;Since the MU-2 weighs less than 12,500 lb, a type rating is not required to fly the plane, so pilots only need a multi-engine rating. However, it is a high performance pressurized aircraft that requires more skill to fly. &lt;a href=&quot;https://www.ainonline.com/aviation-news/aviation-international-news/2010-01-27/new-training-mu-2-reduces-accident-rate&quot; rel=&quot;noreferrer&quot;&gt;Mitsubishi Heavy Industries asked the FAA to create a type rating requirement for the MU-2&lt;/a&gt;, but the FAA decided on creating the SFAR instead, which is more strict than a type rating, especially in the amount of training specifically required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.ainonline.com/aviation-news/aviation-international-news/2008-02-26/sfar-outlines-more-stringent-training-mu-2-pilots&quot; rel=&quot;noreferrer&quot;&gt;Research showed&lt;/a&gt; that the accident rate of the MU-2 from 2001 to 2005 was not really exceptionally high compared to aircraft of similar size and performance. While the accident rate was higher than some, it was also lower than others. However, the FAA received a lot of pressure to create a rule for the MU-2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless, the &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Aircraft-Ownership/Aircraft-Fact-Sheets/Mitsubishi-MU-2&quot; rel=&quot;noreferrer&quot;&gt;accident rate has gone down significantly&lt;/a&gt; since the FAA created new regulations for the plane.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-04T20:02:50.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12407" PostTypeId="1" CreationDate="2015-02-04T20:11:03.820" Score="4" ViewCount="275" Body="&lt;p&gt;How many overhauls will a wide body aircraft composite thrust reverser undergo in its life? (not including damage, etc.)&lt;/p&gt;&#xA;" OwnerUserId="7167" LastEditorUserId="97" LastEditDate="2015-04-22T00:29:39.707" LastActivityDate="2015-06-26T18:22:09.523" Title="On average, how many overhauls will thrust reversers have in their lifetime?" Tags="&lt;aircraft-maintenance&gt;&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12408" PostTypeId="2" ParentId="2482" CreationDate="2015-02-04T20:47:12.357" Score="4" Body="&lt;p&gt;I am doing basic pilot training with the RAF. In our single-engine trainers, we wear and are taught to use parachutes. There is no ejection systems, we have to remove the canopy manually. I don't know why this isn't a standard procedure in all light aircraft, we are doing fairly similar stuff to civilian aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's nice to know that you have a last resort if the engine is on fire. They aren't a huge amount of use below 1500ft however.&lt;/p&gt;&#xA;" OwnerUserId="7169" LastActivityDate="2015-02-04T20:47:12.357" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12410" PostTypeId="2" ParentId="12383" CreationDate="2015-02-04T22:25:05.000" Score="4" Body="&lt;p&gt;During &quot;normal&quot; flight with wings level, the amount of lift generated will vary with the wings angle of attack (alpha). Within the normal flying envelope of the aircraft, the relationship between lift and alpha will be nearly linear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an ideal situation, with symmetric airfoil and not considering fuselage/slipstream effects, at zero degrees alpha, no lift will be generated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There sideslip angle of the aircraft is normally called beta. In normal straight and level flight this is near zero, as no sideways lift is desired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you roll the aircraft 90 degrees and maintain it, you can with an alpha near zero and  a sufficiently high beta angle generate sufficient sideways (now directed skywards) lift to maintain level flight, if the shape and size of the fuselage allow this. (This is the knife edge maneuver illustrated by the picture in Peter Kämpfs reply).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerobatic aircraft can be designed for this. Some aircraft might be able to maintain altitude momentarily in knife edge, but will be unable to maintain the relatively high airspeed required to do this, and will eventually start descending.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastActivityDate="2015-02-04T22:25:05.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12412" PostTypeId="2" ParentId="2287" CreationDate="2015-02-04T22:49:36.607" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/muxDg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/muxDg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Just before the ground impact&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just watch &lt;a href=&quot;https://www.youtube.com/watch?v=keCnK4kh65U&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; of a looping gone bad during a flight display. &lt;a href=&quot;https://youtu.be/keCnK4kh65U?t=90&quot; rel=&quot;nofollow noreferrer&quot;&gt;At 1:30&lt;/a&gt; into the video it becomes painfully obvious by how much both can diverge in extreme situations &lt;em&gt;(shown above).&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight path angle is the difference between pitch attitude and angle of attack. If pitch attitude and angle of attack would be equal, the airplane could only fly straight ahead at the same altitude. Once it climbs, it has to increase pitch attitude at constant angle of attack. With enough thrust or speed, both can be 90° apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider flying inverted: Both are almost 180° apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a dive, again the difference will become large because the flight path angle takes on negative values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more fun it makes to fly an aircraft, the more both angles diverge. Only &lt;a href=&quot;http://en.wikipedia.org/wiki/Airliner&quot; rel=&quot;nofollow noreferrer&quot;&gt;boring aircraft&lt;/a&gt; will keep both of them at similar, low values.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2020-01-15T16:42:10.097" LastActivityDate="2020-01-15T16:42:10.097" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="12413" PostTypeId="1" AcceptedAnswerId="12419" CreationDate="2015-02-04T22:54:43.947" Score="1" ViewCount="823" Body="&lt;p&gt;I am 2nd year PhD student in Physics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you think of any UAV project which won't contribute to army? UAV designing is a career of my dream, but I want to serve the greater good. However, all advances are developing in military field. &lt;/p&gt;&#xA;" OwnerUserId="7173" LastEditorUserId="7173" LastEditDate="2015-02-05T01:12:06.723" LastActivityDate="2015-02-05T03:15:42.073" Title="UAV project in aerospace department" Tags="&lt;usa&gt;&lt;unmanned-aerial-vehicle&gt;&lt;career&gt;" AnswerCount="3" CommentCount="6" ClosedDate="2015-02-05T07:36:29.137" ContentLicense="CC BY-SA 3.0" />
  <row Id="12414" PostTypeId="2" ParentId="12401" CreationDate="2015-02-04T23:03:07.917" Score="15" Body="&lt;p&gt;All good answers, just to add:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, our regulations are usually more stringent such as weather minimums for example (filing, including an alternate, fuel requirements, night, etc.).  However, with other things we do have a bit more leeway than civilians.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not going to list all the differences, but if you want you could check out some of the publications we're bound by:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;AFI 11-202 Vol 3&#xA;AFMAN 11-217 Vol 1&#xA;AFMAN 11-217 Vol 2&#xA;AFMAN 11-217 Vol 3&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;That's just a subset of what binds us;  I'm not going to list them all here but we have regulations and procedures for specific jets based on MAJCOMs, Ops Groups, Wings, etc.  The military changes a lot more quickly and often than civilian flying does.  Additionally flying in one MAJCOM may be totally different than another.  Likewise, one airfield, wing, or squadron will have totally different SOPs than another airfield, wing, or squadron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, although VFR aircraft CAN fly through a MOA, please don't do it.  It interrupts our  ops since we have to call knock-it-off and either wait for you to leave or proceed to a different area.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-04T23:03:07.917" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12415" PostTypeId="2" ParentId="12413" CreationDate="2015-02-04T23:23:57.497" Score="1" Body="&lt;p&gt;One would be the &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-059-DFRC.html#.VNKopUI1RC4&quot; rel=&quot;nofollow&quot;&gt;Aurora Flight Sciences Perseus&lt;/a&gt;, which started as an unmanned instrument carrier for flights into the south polar vortex, in order to study ozone depletion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But guess what: Development took much longer than initially expected, and funding gaps could only be filled with &lt;a href=&quot;http://www.darpa.mil/default.aspx&quot; rel=&quot;nofollow&quot;&gt;DARPA&lt;/a&gt; money. In the end, military contracts keep many high-tech companies alive which could not support themselves exclusively with civilian money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your field of interest has military applications, it will be very hard to stay true to your ethical standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would dispute your claim, however, that all advances take only place in the military field. Apart from GPS, many advances which make UAVs practical are connected to civilian-driven technological progress. Only when it comes to issues like reserving airspace for UAV operations, the military is in a much easier position than civilian operators which must wait for slow-moving government bureaucracies to adapt to progress. The discussions we had with the FAA in 1990 on how to operate UAVs were surreal.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-04T23:31:45.383" LastActivityDate="2015-02-04T23:31:45.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12416" PostTypeId="2" ParentId="12413" CreationDate="2015-02-04T23:44:08.983" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://www.amazon.com/b?node=8037720011&quot; rel=&quot;nofollow&quot;&gt;Amazon&lt;/a&gt; wants to deliver packages with UAVs. So does &lt;a href=&quot;http://www.wsj.com/articles/google-reveals-delivery-drone-project-1409274480&quot; rel=&quot;nofollow&quot;&gt;Google&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even military contractors like &lt;a href=&quot;http://www.boeing.com/boeing/Features/2013/07/corp_spuds_07_29_13.page&quot; rel=&quot;nofollow&quot;&gt;Boeing&lt;/a&gt; and &lt;a href=&quot;http://www.fool.com/investing/general/2013/12/08/northrop-grumman-wants-to-sell-unmanned-drones-to.aspx&quot; rel=&quot;nofollow&quot;&gt;Northrup Grumman&lt;/a&gt; see applications in agriculture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there's also a growing field in selling them for &lt;a href=&quot;http://ardrone2.parrot.com/&quot; rel=&quot;nofollow&quot;&gt;retail&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While other countries have better regulatory processes right now, the FAA is preventing much progress in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you come up with your own idea, then why not start your own business? There are lots of possibilities.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-04T23:44:08.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12418" PostTypeId="2" ParentId="12367" CreationDate="2015-02-05T01:53:31.267" Score="1" Body="&lt;p&gt;Every country in the world generally operates from their own manuals. The International Civil Aviation Organization, ICAO, also has a standard that it recommends, and many countries have copied. From what I've been told, back when ICAO started up, they basically copied for their manuals, what the FAA had and used at the time. Over the years, the two have diverged in their designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no official/major standard, but most countries hold towards the ICAO recommendations, at least in general form. ATC's main purpose is the safe, orderly and expeditious movement of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-02-05T01:53:31.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12419" PostTypeId="2" ParentId="12413" CreationDate="2015-02-05T03:15:42.073" Score="1" Body="&lt;p&gt;Here are a few non-military ways in which drones have been used:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://youtu.be/DvbDtBuZjD4&quot; rel=&quot;nofollow&quot;&gt;the city of Ottawa has been using drones to scare away geese&lt;/a&gt; in order to limit local goose population;&lt;/li&gt;&#xA;&lt;li&gt;wildlife surveys, in particular for endangered species. This has been done for &lt;a href=&quot;http://blogs.scientificamerican.com/extinction-countdown/2012/09/27/drones-help-conserve-sumatran-orangutans-wildlife/&quot; rel=&quot;nofollow&quot;&gt;orang-outans&lt;/a&gt;, whales, &lt;a href=&quot;https://www.fort.usgs.gov/science-feature/127&quot; rel=&quot;nofollow&quot;&gt;cranes&lt;/a&gt; and others;&lt;/li&gt;&#xA;&lt;li&gt;fighting illegal hunting;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.firechief.com/2014/03/20/5-drone-technologies-firefighting/&quot; rel=&quot;nofollow&quot;&gt;assisting firefighters&lt;/a&gt;;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.wired.com/2013/02/drone-farm/&quot; rel=&quot;nofollow&quot;&gt;dusting crops&lt;/a&gt; ;&lt;/li&gt;&#xA;&lt;li&gt;replacing helicopter pilots in taking aerial footage for movies;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://pix4d.com/&quot; rel=&quot;nofollow&quot;&gt;cartography&lt;/a&gt; (though this is a civil and military application);&lt;/li&gt;&#xA;&lt;li&gt;search and rescue missions;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.enquirer.com/editions/2003/05/26/loc_roaddrones26.html&quot; rel=&quot;nofollow&quot;&gt;traffic monitoring&lt;/a&gt; to determine congested roads or find the quickest route for emergency vehicles;&lt;/li&gt;&#xA;&lt;li&gt;enforcing environmental laws (e.g. determining where &lt;a href=&quot;http://www.suasnews.com/2012/01/11389/dallas-meat-packing-plant-investigated-after-drone-images-reveal-pollution/&quot; rel=&quot;nofollow&quot;&gt;dumping of toxic waste&lt;/a&gt; is done and by whom)&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-02-05T03:15:42.073" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12420" PostTypeId="1" CreationDate="2015-02-05T03:25:55.663" Score="5" ViewCount="2020" Body="&lt;p&gt;About a year ago, I bought myself a &lt;a href=&quot;http://www.bose.com/controller?url=/shop_online/headphones/aviation_headsets/a20/index.jsp#top&quot;&gt;Bose A20&lt;/a&gt;.  Within two weeks, I had returned it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will be the first to say that the noise reduction for the A20 was fantastic.  The headset was amazingly light, and clarity was superb.  The reason I returned it was because after wearing it for an hour or two, I would start feeling a sharp pain on the top of my head, where the headset rested.  I'm not the only one to have this happen:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unfortunately, I have decided to return these headsets in the 30 day trial period. After the first week, these headsets started to &quot;hotspot&quot; the top center of my head and became uncomfortable after several straight hours of continuous flying. The sound quality was excellent but it came down to a comfort issue. There were a few annoying things.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here's another...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On one trip the airplane was equipped with a Bose headset and I thought I would let my wife use it. After 1 hour her head had a bad hotspot and she made me switch. After 30 minutes wearing the Bose I too had a hotspot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And a quote from the A20 owners manual:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During a long flight, you may feel a slight pressure point, which can be relieved by adjusting the headband position. Your experience with using the headset will help establish a sense of how it should sound and feel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I wanted so badly to like that headset (in fact, I still do).  My faithful David Clark will be heading back to the factory for repair soon, and I'm willing to give the A20 another chance, if there's a way to keep that top-of-head hotspot from forming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there a way to prevent (not relieve) the hotspot caused by wearing a Bose A20 for long periods of time?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="64" LastEditDate="2015-02-05T16:33:57.510" LastActivityDate="2015-02-05T18:26:31.740" Title="Is there a way to prevent (not relieve) the hotspot caused by wearing a headset for long periods of time?" Tags="&lt;equipment&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12421" PostTypeId="1" AcceptedAnswerId="12437" CreationDate="2015-02-05T04:49:52.390" Score="9" ViewCount="9655" Body="&lt;p&gt;I am interested in knowing all regulations apply to about what an owner operator needs to do to legally rent their aircraft out for private/business usage or flight instruction.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What inspections?&lt;/li&gt;&#xA;&lt;li&gt;Insurance requirements? &lt;/li&gt;&#xA;&lt;li&gt;Anything else?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I assume renting your aircraft out is under part 91.&lt;/p&gt;&#xA;" OwnerUserId="1315" LastEditorUserId="65" LastEditDate="2015-02-05T21:30:28.283" LastActivityDate="2017-01-18T21:32:13.167" Title="What does an owner/operator need to do to legally rent out their aircraft?" Tags="&lt;faa-regulations&gt;&lt;rental&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12422" PostTypeId="1" AcceptedAnswerId="12425" CreationDate="2015-02-05T05:25:15.167" Score="4" ViewCount="600" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=2jBvbpbq0SM&quot; rel=&quot;nofollow&quot;&gt;This video&lt;/a&gt; suggests a time-based approach to landing aircraft separation is preferable to the distance-based standard commonly used.  It advertises a greater arrival volume at airports, as strong headwinds can delay the time between aircraft landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the pros and cons for a change in standard?  Under TBS, aircraft would be spaced more closely (distance-wise) on approach during strong headwinds.  Does this present a possible hazard to trailing aircraft if something goes wrong late in the approach (like &lt;a href=&quot;https://www.youtube.com/watch?v=1N5THRSp4hM&quot; rel=&quot;nofollow&quot;&gt;this runway incursion&lt;/a&gt;?)&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="572" LastEditDate="2015-02-19T08:37:57.900" LastActivityDate="2015-02-19T08:37:57.900" Title="What are the differences and benefits between/of time-based vs distance-based separation?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;landing&gt;&lt;separation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12423" PostTypeId="2" ParentId="12367" CreationDate="2015-02-05T05:55:32.990" Score="0" Body="&lt;p&gt;The FAA and EUROCONTROL jointly published a document in 2013 that provides a comparison of air traffic management starting in section 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most differences have to do with the fact that the EU is comprised of multiple countries, while in the US, the FAA has full authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Organization:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The US system is operated by one single service provider using the same tools and equipment, communication processes and a common set of rules and procedures ... [while] the European system is much more fragmented and ANSPs are still largely organised by State boundaries.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Route/airspace management (including special use airspace):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[T]he Federal Aviation Administration (FAA) is responsible for airspace management and route design[;] in the amalgamated European ATM system, airspace design remains the prerogative of the individual States.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/us_eu_comparison_2013.pdf&quot; rel=&quot;nofollow&quot;&gt;Direct link&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-02-05T05:55:32.990" CommentCount="0" CommunityOwnedDate="2015-02-05T05:55:32.990" ContentLicense="CC BY-SA 3.0" />
  <row Id="12424" PostTypeId="2" ParentId="2850" CreationDate="2015-02-05T06:17:13.233" Score="2" Body="&lt;p&gt;The short answer is: commercial flights (money is involved) are almost always illegal. Hobby flights (no $) are not controlled by very many binding laws, but &quot;strong guidance&quot; is given in the above poster, including 1) not over groups of people, not near airports, etc., and (more controversial) always below 400 feet. The legal basis for the statement that you &quot;must follow safety guidelines&quot; does not exist. People in my club go out in the desert and fly several thousand feet high, for example. But they would never do that at our regular field, because they know it is stupid, unsafe, and will upset the local helicopters! &#xA;  This is a very controversial and evolving area. The FAA is attempting to assert much greater de-facto jurisdiction, for example by proposing a definition that on paper might regulate unpowered balsa wood aircraft. It &lt;em&gt;is&lt;/em&gt; pretty clear that the FAA has the right to forbid commercial flights, although a recent court case has cast some doubt on the actual limits.&lt;br&gt;&#xA;  Check out the Academy of Model Aeronautics for the organized hobbyist's view. &lt;a href=&quot;http://www.modelaircraft.org/documents.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.modelaircraft.org/documents.aspx&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="7181" LastActivityDate="2015-02-05T06:17:13.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12425" PostTypeId="2" ParentId="12422" CreationDate="2015-02-05T07:45:18.517" Score="3" Body="&lt;p&gt;There is more information available from NATS on the website on &lt;a href=&quot;http://nats.aero/blog/2014/02/explaining-time-based-separation-heathrow/&quot; rel=&quot;nofollow&quot;&gt;Time Based Separation&lt;/a&gt; [TBS] and from a very descriptive &lt;a href=&quot;http://nats.aero/blog/wp-content/uploads/2014/02/TBS_ReadMode.pdf&quot; rel=&quot;nofollow&quot;&gt;Infographic on TBS&lt;/a&gt;&lt;sup&gt; PDF&lt;/sup&gt;. While Heathrow (EGLL) is the first airport where this is being researched and tested, there are als other works, such as a research paper called &lt;a href=&quot;http://atm2003.eurocontrol.fr/past-seminars/5th-seminar-budapest-hungary-june-2003/papers/paper_005&quot; rel=&quot;nofollow&quot;&gt;Potential Benefits of a Time-based Separation Procedure to maintain the&#xA;Arrival Capacity of an Airport in strong head-wind conditions&lt;/a&gt;&lt;sup&gt; PDF&lt;/sup&gt; which applies TBS at Charles Des Gaulles (LFPG). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main focus of using TBS is to increase airport capacity during strong headwind operations, which significantly decrease groundspeed and therefore traffic flow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of the papers I have found speak of hazards related to decreasing the lateral distance between flights. The general idea seems to be that the minimal safety gain accompanying lower groundspeeds due to strong headwinds (lower GS means lower closure rate to objects / stationary traffic on ground) can be partially sacrificed and offset by TBS to maintain airport capacity or reduce the impact of the strong headwinds on airport capacity. This sacrifice becomes available since stronger headwinds also aid the dissipation of wake vortex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The below table is based on own calculations, assuming constant approach speeds.&#xA;It should show you how the time to cover a set distance increases with decreasing ground speeds, which means that e.g. it takes longer to cover 3nm to reach the runway threshold. Reducing the lateral separation (the values chosen are deliberately a bit extreme, as none of the papers mentioned a formula to calculate TBS distances) reduces time to cover the distance, but covering 2.5nm at 130 GS is becoming quite close to 3nm at 150 GS.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;+-----+-----+-------+-----+&#xA;| GS  | 3nm | 2.5nm | 2nm |&#xA;+-----+-----+-------+-----+&#xA;| 150 |  72 |    60 |  48 |&#xA;| 140 |  76 |    64 |  51 |&#xA;| 130 |  83 |    69 |  55 |&#xA;+-----+-----+-------+-----+&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-05T08:09:07.260" LastActivityDate="2015-02-05T08:09:07.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12426" PostTypeId="2" ParentId="1152" CreationDate="2015-02-05T08:09:38.453" Score="2" Body="&lt;p&gt;Bernoulli's Principle (airfoil shape) is only one of the lifting forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equally important is deflection (Newton's law), and on propellor aircraft, accelerated airflow.&lt;/p&gt;&#xA;" OwnerUserId="7182" LastActivityDate="2015-02-05T08:09:38.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12428" PostTypeId="2" ParentId="12356" CreationDate="2015-02-05T13:21:21.473" Score="3" Body="&lt;p&gt;Lowest cost is king if you can get away with it.&lt;br&gt;&#xA;Personal air vents provide more flexibility than if they were absent and the overall cost is lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If personal airjets are available then the jet temperature and maximum available flow can be set to suit people with preferences on the cold side of normal, while the mean temperature can be hotter than would suit a significant proportion of people. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, instead, the cabin needed to be maintained at a temperature that most people would consider acceptable then, in the absence of personal vents, the whole cabin would need to be cooled to that temperature. Some people would then feel too cold, which can be dealt with by clothing or blankets, and most people would be comfortable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first case you have lower than otherwise energy use with &quot;outliers&quot; being addressed with airjets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the second case you have higher than otherwise energy use with outliers being addressed with blankets. The energy cost of the blankets is zero but overall it still costs more this way.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;FWIW I'm an air-jet loving traveller and greatly dislike aircraft without them. &lt;/p&gt;&#xA;" OwnerUserId="4371" LastActivityDate="2015-02-05T13:21:21.473" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12429" PostTypeId="2" ParentId="12383" CreationDate="2015-02-05T14:09:57.990" Score="-1" Body="&lt;p&gt;Only if there is a force vector component pointing up.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Model planes tend to have a large rudder which provides lift when turned 90 degrees.  Fighter jets have vectored nozzles that can turn to provide lift in a 90 degree maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most passenger airplanes cannot perform such maneuvers.&lt;/p&gt;&#xA;" OwnerUserId="5550" LastActivityDate="2015-02-05T14:09:57.990" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12430" PostTypeId="2" ParentId="12356" CreationDate="2015-02-05T14:20:30.837" Score="1" Body="&lt;p&gt;Make the passenger &lt;em&gt;feel&lt;/em&gt; he's in control of something.&#xA;The practical use is to fight rising temperatures and odors, but i also quite like the oxygen.&lt;/p&gt;&#xA;" OwnerUserId="7183" LastActivityDate="2015-02-05T14:20:30.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12431" PostTypeId="1" CreationDate="2015-02-05T14:29:12.793" Score="4" ViewCount="1083" Body="&lt;p&gt;I know that &lt;a href=&quot;http://en.wikipedia.org/wiki/Minimum_safe_altitude_warning&quot; rel=&quot;nofollow&quot;&gt;Minimum safe altitude warning (MSAW)&lt;/a&gt; alerts ATC and pilots if an airplane is under the risk of controlled flight into terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when is this alarm triggered? What is the minimum altitude for it to trigger? If a plane is landing, should it be triggered just before landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will confuse ATC if every plane that is landing triggers that alarm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There must be some limitations. So, what are they?&lt;/p&gt;&#xA;" OwnerUserId="7115" LastEditorUserId="22726" LastEditDate="2020-04-20T22:29:59.437" LastActivityDate="2020-04-20T22:29:59.437" Title="When is Minimum Safe Altitude Warning triggered?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;flight-instruments&gt;&lt;msaw&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12433" PostTypeId="2" ParentId="1152" CreationDate="2015-02-05T15:30:23.523" Score="3" Body="&lt;p&gt;Short answer is &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/wrong1.html&quot; rel=&quot;nofollow&quot;&gt;that explanation is wrong&lt;/a&gt;. How planes actually generate lift is far more complicated.&lt;/p&gt;&#xA;" OwnerUserId="7184" LastActivityDate="2015-02-05T15:30:23.523" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12435" PostTypeId="2" ParentId="12420" CreationDate="2015-02-05T16:33:16.077" Score="3" Body="&lt;p&gt;The best way to prevent the &quot;hot spot&quot; pressure point from the headset band is to wear a headset that doesn't have a top band (like &lt;a href=&quot;https://www.quiettechnologies.com&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; or &lt;a href=&quot;http://www.clarityaloft.com&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;). Of course this requires that you be able to wear an in-ear headset, and some people are more bothered by that than by the headband.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short of wearing in-ear headsets there are numerous &lt;a href=&quot;http://www.aircraftspruce.com/menus/av/headsetx_headband.html&quot; rel=&quot;nofollow&quot;&gt;different headset band pads&lt;/a&gt; you can try - I know at least one person flying with &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/7440?gclid=CjwKEAiAxsymBRCegqiLzI7Q1S8SJADOgQrzrpf87i3CjFVmOV18un8kWLFoELjansC3-kyJgDwwzBoCtNHw_wcB&quot; rel=&quot;nofollow&quot;&gt;this sheepskin pad&lt;/a&gt;.&lt;br&gt;&#xA;Some combination of the right headband position and the right pad should make your headset more comfortable for long flights.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-02-05T18:26:31.740" LastActivityDate="2015-02-05T18:26:31.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12436" PostTypeId="1" CreationDate="2015-02-05T16:39:04.670" Score="5" ViewCount="538" Body="&lt;p&gt;I am current as PIC in type on a jet requiring two crew members. I will be out of currency as PIC soon and my company wants me to move to SIC position when that happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I required to have training specified under &lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/61.55&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.55&lt;/a&gt; for SIC if I am already type rated in the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="7188" LastEditorUserId="69" LastEditDate="2017-05-08T17:59:02.787" LastActivityDate="2017-05-08T17:59:02.787" Title="Is training required under §61.55 to move from PIC to SIC?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;currency&gt;&lt;logbook-endorsements&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12437" PostTypeId="2" ParentId="12421" CreationDate="2015-02-05T17:59:36.117" Score="4" Body="&lt;p&gt;As Farhan noted, the rules are essentially the same as &lt;a href=&quot;https://aviation.stackexchange.com/q/1452/65&quot;&gt;if you buy a plane to provide instruction in it&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Inspections and Maintenance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In addition to your required annual inspection you will also be required to complete a 100-hour inspection every 100-hours of operation.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Insurance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You will need a commercial insurance policy which allows you to rent the aircraft.&lt;br&gt;&#xA;This policy covers the &lt;em&gt;aircraft&lt;/em&gt;, so you will also need (or at least want) general liability insurance and all the other trimmings that come with operating a business.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Everything Else&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This is a broad category. There's no way we can cover it all. You will however need to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Maintaining an adequate stock of &quot;service spares&quot; to maintain the aircraft.&lt;/strong&gt;&lt;br&gt;&#xA;Tires, light bulbs, oil, oil filters, 5606 hydraulic fluid, etc. - As an individual owner you may be OK with being down for a week waiting for parts, but as a rental operation that will lose you customers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Having a relationship with a mechanic to do the maintenance&lt;/strong&gt;&lt;br&gt;&#xA;Owner-Performed Preventive Maintenance goes out the window when the aircraft becomes a rental - you may still be able to assist your mechanic, but you can no longer do &amp;amp; sign-off on things like oil changes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Vetting your renters&lt;/strong&gt;&lt;br&gt;&#xA;Rental aircraft at an FBO/Flight School live a hard life. If you like your plane and want it to stay in good condition you'll need to vet your renters a bit more thoroughly than &quot;You have a pilot's license and you went around the pattern without hitting anything&quot; - Find the kind of pilots who will police their trash from the cabin, lean the mixture appropriately, etc.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-07T17:15:30.247" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12438" PostTypeId="2" ParentId="12377" CreationDate="2015-02-05T18:01:05.163" Score="0" Body="&lt;p&gt;Assuming you are flying in an FAA &quot;controlled&quot; area, you &quot;&lt;strong&gt;must document and record the following time [...] : (1) Training and aeronautical experience used to meet the requirements for a certificate, rating, or flight review of this part.&lt;/strong&gt;&quot; (FAR §61.51(a)).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now this is for you, but your instructor should have a look at FAR §61.189(a), where it says: &quot;&lt;strong&gt;A flight instructor must sign the logbook of each person to whom that instructor has given flight training or ground training&lt;/strong&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;strong&gt;you&lt;/strong&gt; don't have to log the time, if you don't want it to count to your training, but your instructor is required to sign your logbook if he gives you any flight training. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For every day life I would say this should be interpreted as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Yes you have to log your flight time when you train for a license!&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2015-02-05T18:01:05.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12439" PostTypeId="1" AcceptedAnswerId="12441" CreationDate="2015-02-05T18:07:24.807" Score="29" ViewCount="9783" Body="&lt;p&gt;If you do a Google or Bing search for &quot;Aircraft Pilot Seat&quot; then choose images, you might notice a large number, perhaps majority of them, have a notch cut out of the front of the seat. What is this notch for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notches are circled here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QtfTT.jpg&quot; alt=&quot;Notches pointed out in 737-800 cockpit&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://on-the-step.com/what-pilots-are-saying-about-the-asiana-214-crash/&quot;&gt;Original Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Please, no potty humor or scatological jokers need apply here)&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="487" LastEditDate="2015-02-06T00:38:53.027" LastActivityDate="2019-03-21T21:10:26.643" Title="Aircraft pilot's seats: what is the notch for?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12440" PostTypeId="2" ParentId="12439" CreationDate="2015-02-05T18:14:31.353" Score="13" Body="&lt;p&gt;It's for the control column when it is moved fully aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TzOuy.jpg&quot; alt=&quot;Picture 1&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://flysafe.raa.asn.au/constructors/je_1896painttest.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you only needed a crotch strap, it can be installed mid-seat.&lt;/p&gt;&#xA;" OwnerUserId="7190" LastEditorUserId="1467" LastEditDate="2019-03-14T11:19:22.160" LastActivityDate="2019-03-14T11:19:22.160" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12441" PostTypeId="2" ParentId="12439" CreationDate="2015-02-05T18:15:33.530" Score="33" Body="&lt;p&gt;It's either for clearance of the column of the yoke or moving the crotch strap of the harness closer to the body of the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternative yoke designs remove the need for the notch:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XsLN5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XsLN5.jpg&quot; alt=&quot;Twin otter cockpit&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/9/9/8/0821899.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternative control methods like the Airbus sidestick also remove the need. As Henning Makholm noted, the seat strap just goes through the cushion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rLdZ3.jpg&quot; alt=&quot;Airbus cockpit&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="8282" LastEditDate="2019-03-21T21:10:26.643" LastActivityDate="2019-03-21T21:10:26.643" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="12444" PostTypeId="2" ParentId="12436" CreationDate="2015-02-05T20:40:30.097" Score="7" Body="&lt;p&gt;No training needed.  If you are typed in the aircraft, none of the SIC type stuff applies (that is just an ICAO formality and is superseded by having a normal type rating).  As long as you meet the requirements to act as SIC (landing currency, company training currency, etc) you are good to transition to the right seat with no additional training.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-02-05T20:40:30.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12445" PostTypeId="1" AcceptedAnswerId="12748" CreationDate="2015-02-05T21:50:58.133" Score="8" ViewCount="2003" Body="&lt;p&gt;Today I saw this &lt;a href=&quot;https://vimeo.com/92499008&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt; on Vimeo that shows a pilot flying a new solar glider (N- registered aircraft) in Italy without wearing a parachute (I believe in US is not mandatory).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually here in Italy it is mandatory to wear parachutes in gliders (at least I- registered). In our club we carry them also on our D- gliders but I don't know if it is also mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the scope of local regulations for foreign aircrafts? Do they have to comply also with this issue or is it up to the user, since it is a factor that only affects him?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please feel free to edit my question with better words if my text is incomprehensible.&lt;/p&gt;&#xA;" OwnerUserId="7072" LastEditorUserId="62" LastEditDate="2015-02-18T17:55:46.710" LastActivityDate="2016-10-19T07:14:54.587" Title="Do glider pilots have to wear parachute in countries where mandatory even if flying with a foreign glider?" Tags="&lt;faa-regulations&gt;&lt;glider&gt;&lt;international&gt;&lt;parachute&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12446" PostTypeId="2" ParentId="12439" CreationDate="2015-02-06T00:59:42.613" Score="4" Body="&lt;p&gt;Pilot seats have a five point harness with a crutch strap.  The strap needs to be snug to provide any value in a sudden stop, hence the 'notch' to bring it as close to the body as possible.&lt;/p&gt;&#xA;" OwnerUserId="7194" LastActivityDate="2015-02-06T00:59:42.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12447" PostTypeId="2" ParentId="701" CreationDate="2015-02-06T02:30:15.880" Score="7" Body="&lt;p&gt;Low wing aircraft have the advantage in a water landing because the wings can keep much of the fuselage above water, as well as provide a temporary staging area for deplaning passengers.  In a high aircraft, you would be lucky to get out before drowning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise, on land, low wing aircraft are easier to control in a wheels up landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low wing aircraft can be designed with a more widely spaced and shorter main gear, which is more stable.  Most high wing aircraft use fuselage sponsons (MU2, ATR-42/72, Do228/328, BAe-146/Avro RJ, C-130) to house the main gear, providing a relatively narrow, and therefore, less stable track.  For those high wing designs that house the main gear in wing-mounted engine nacelles or in the wings themselves (Twin Commander, F-27/227, Dash 7/8, B-24/32), the gear must be made much longer, and therefore, much heavier.  A long main gear design is also more prone to structural failure in a hard or poorly executed crosswind landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low wing aircraft are easier to refuel, and if equipped with wing-mounted engines, those would be easier to service. &lt;/p&gt;&#xA;" OwnerUserId="7196" LastActivityDate="2015-02-06T02:30:15.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12448" PostTypeId="2" ParentId="606" CreationDate="2015-02-06T02:41:27.757" Score="4" Body="&lt;p&gt;&lt;strong&gt;Force&lt;/strong&gt;'s answer is very good.  But the statement &quot;additional mass only increases cruise speed, but not the travel distance&quot;, true for any one glide, doesn't take account of the fact that conditions suitable for soaring typically exist for a limited time each day - so increasing cruise speed definitely does increase distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;StallSpin&lt;/strong&gt;'s point about reduced effect of turbulence on a ballasted glider is significant.  This is best seen when flying a ridge, which in strong wind can be very rough.  The ballasted glider, suffering less acceleration imposed by the rough air, can fly faster and lower, where the horizontal wind component is less, requiring a smaller crab angle.&lt;/p&gt;&#xA;" OwnerUserId="7176" LastActivityDate="2015-02-06T02:41:27.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12449" PostTypeId="1" AcceptedAnswerId="12451" CreationDate="2015-02-06T02:42:36.967" Score="40" ViewCount="14888" Body="&lt;p&gt;Instead of being consistently-dense, the afterburner exhaust looks &amp;quot;pulsed&amp;quot; in these pictures below.  Is this a trick of the camera, a natural result of interaction with the air, or is there some design science in the propulsion system that causes this effect?&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FcvQ0.jpg&quot; alt=&quot;F-15 afterburners&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fk8SC.jpg&quot; alt=&quot;F-22 afterburners&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XZFJU.jpg&quot; alt=&quot;F-22 firing an AIM-120 AMRAAM&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2020-10-02T14:39:47.680" LastActivityDate="2020-10-02T14:39:47.680" Title="Why does afterburner exhaust have &quot;pulses&quot;?" Tags="&lt;jet-engine&gt;&lt;military&gt;&lt;engine&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="12451" PostTypeId="2" ParentId="12449" CreationDate="2015-02-06T03:04:59.453" Score="44" Body="&lt;p&gt;Those are known as &amp;quot;Mach diamonds&amp;quot; or &amp;quot;Shock diamonds&amp;quot; (and a number of other names) and are not a characteristic of the afterburner per se but are formed by standing waves in the exhaust when the pressure of the expanded exhaust gases do not exactly match external ambient pressure. They can be formed by either over-expansion or under-expansion of the exhaust gases. The diamonds form at the transition from sonic to supersonic flow which occurs immediately on the &amp;quot;downstream&amp;quot; side of a rocket or jet engine nozzle.&lt;/p&gt;&#xA;&lt;p&gt;Photo from the link below:&lt;/p&gt;&#xA;&lt;p&gt;SR-71 Blackbird taking off.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gDet8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gDet8.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In rockets, flow through such a nozzle is always sonic at the throat (in all except trivially low pressure systems where it can be subsonic - but these are not usually encountered in practice.&lt;/p&gt;&#xA;&lt;p&gt;In jet engines, whether flow is sonic or supersonic at the exhaust depends on the design which in turn tends to depend on the application. &amp;quot;Pure jet&amp;quot; engines which use a combustion driven compressor to compress input air and which develop their thrust from the jet exhaust will usually have supersonic exhausts. Ongoing development has led to a range of &amp;quot;jet&amp;quot; engine types with somewhat differing capabilities - turbojet (&amp;quot;pure&amp;quot; jet), turbofan (jet driven internal &amp;quot;fan&amp;quot; produces air which partially bypasses jet proper), turboprop (jet drives external propeller),propfan (turboprop on steroids optimised for close to Mach 1 cruise) and some fellow travelers such as turboshaft - like a turboprop but with shaft output - useful if you want to power eg a helicopter.&lt;/p&gt;&#xA;&lt;p&gt;In a turbo-fan engine the amount of air which bypasses the jet engine proper is governed by the &amp;quot;bypass ratio&amp;quot;. High bypass engines send most air past the jet proper to be combined with the jet exhaust and form the actual engine exhaust. Pure jet or some &amp;quot;low bypass ratio&amp;quot; turbo fan engines may have supersonic exhausts while &amp;quot;high bypass ratio&amp;quot; turbofan are always subsonic. Modern long distance aircraft (especially airliners) which aim for maximum fuel economy tend to have high bypass ratios. As Mach diamonds are only associated with trans-sonic operation you will not see Mach diamonds from eg a 747.&lt;/p&gt;&#xA;&lt;p&gt;So, low bypass fanjets &lt;em&gt;may&lt;/em&gt; have supersonic exhausts for part of their operation. A turbojet may be sub or super sonic and afterburner will almost always (but not necessarily in theory) produce supersonic outlet flow.&lt;/p&gt;&#xA;&lt;p&gt;In systems which do have supersonic exit exhaust velocities, as the flow changes from sonic at the nozzle throat to supersonic in the expansion system the aim is to make the exit pressure exactly match ambient. &amp;quot;Exactly&amp;quot; never exactly happens in practice. Where the mismatch occurs there will be a shockwave - an &amp;quot;impedance mismatch in another perspective - and the visible evidence of this are the Mach Diamonds.&lt;/p&gt;&#xA;&lt;p&gt;As both exhaust pressure and ambient pressure change with conditions there will essentially always be some degree of such shock waves present in &amp;quot;qualifying&amp;quot; systems, but more so when the engine operation departs more significantly from the ideal. Smaller versions may not be obvious without careful examination. As the overall system is usually optimised for &amp;quot;normal&amp;quot; conditions, afterburner operation is more likely to cause a major pressure mismatch as it deviates from normal use.&lt;/p&gt;&#xA;&lt;p&gt;An exception would occur if the designers decided they wanted absolutely maximum performance from afterburner under given conditions (so that eg an interceptor could achieve absolute maximum velocity when needed) - in which case the Mach diamonds could be minimised on afterburner and would be more pronounced in normal operation.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;See this page for some good photos and the diagrams below -&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aerospaceweb.org/question/propulsion/q0224.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Aerospace - Shock Diamonds and Mach Disks&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Below: creation of Mach Diamonds from under-expanded flow.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bTsw7.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Below: - creation of Mach Diamonds from over-expanded flow.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v1Wpd.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Good explanation with pictures here - &lt;a href=&quot;http://en.wikipedia.org/wiki/Shock_diamond&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Wikipedia - Shock Diamond&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.co.nz/search?q=mach+diamonds&amp;amp;biw=1745&amp;amp;bih=977&amp;amp;tbm=isch&amp;amp;tbo=u&amp;amp;source=univ&amp;amp;sa=X&amp;amp;ei=8yvUVN3DNoe0mAWH-IDwDg&amp;amp;sqi=2&amp;amp;ved=0CCsQsAQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Numerous relevant images&lt;/a&gt; - each linked to a related web page.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Related:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia - Jet Engine&lt;/a&gt; excellent.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_178&quot; rel=&quot;nofollow noreferrer&quot;&gt;He178 0- the very first Jet aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/airplane/turbth.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA visual Turbojet simulation&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4371" LastEditorUserId="4371" LastEditDate="2020-10-02T11:17:43.163" LastActivityDate="2020-10-02T11:17:43.163" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="12452" PostTypeId="1" AcceptedAnswerId="12488" CreationDate="2015-02-06T05:05:01.300" Score="13" ViewCount="16675" Body="&lt;p&gt;What is the typical aircrew for a civilian (not military) &lt;strong&gt;cargo&lt;/strong&gt; flight? From my limited web searches, it seems that there would be three crew members:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Pilot&lt;/li&gt;&#xA;&lt;li&gt;Co-pilot (I assume there must always be minimum of two people in the flight deck, in case anything happens to the primary pilot)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Loadmaster&quot;&gt;Loadmaster&lt;/a&gt;, a crew member responsible for loading and unloading cargo, and for assuring load balance during the flight.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Are these indeed three minimal, required crew members for a cargo flight? Are there any others that are required or optional? What is typical for a long haul cargo flight, and what is typical for short haul. (Rather than precisely defining how many hours is long haul or short haul--I'm not even sure--I'll leave that open for the answerers, since I'm really not sure what to expect.)&lt;/p&gt;&#xA;" OwnerUserId="7199" LastEditorUserId="7199" LastEditDate="2015-02-06T13:39:51.043" LastActivityDate="2015-02-07T01:00:53.507" Title="What is the typical aircrew for a cargo flight?" Tags="&lt;crew&gt;&lt;cargo&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12453" PostTypeId="2" ParentId="12383" CreationDate="2015-02-06T05:36:03.247" Score="0" Body="&lt;p&gt;Not really all that complicated. It all depends on if the specific airframe is designed for such maneuvers and the power plant is robust enough for sustained operation in this mode of flight. MANY aircraft can sustain flight in horizontal flight with the wings 90 degrees to the ground. The Navy's Blue Angels and the USAF's Thunderbirds do this on a daily basis at their airshows. Moving an airfoil to 90 degrees, 180 degrees, 270 degrees, or even through 360 degrees (barrel roll) is accomplished through the wings ailerons. Most aircraft capable of aerobatic maneuvers have trim tabs on ailerons, rudder and elevator to assist in prolonging such maneuvers. Although most light aircraft do not have trim tabs on the rudder and elevator. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have witnessed a Pilatus Porter (Fairchild) take off near vertical with less than a 40 foot ground roll. Granted it was stripped down and supercharged but it performed as advertised. I think there was a Youtube type video on this out there somewhere at one point. The demonstration was performed by the US Army in the 1970s.&lt;/p&gt;&#xA;" OwnerUserId="7198" LastEditorUserId="19" LastEditDate="2015-02-06T06:42:44.327" LastActivityDate="2015-02-06T06:42:44.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12455" PostTypeId="2" ParentId="12449" CreationDate="2015-02-06T07:54:20.553" Score="15" Body="&lt;p&gt;This effect needs&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;supersonic exhaust speeds and&lt;/li&gt;&#xA;&lt;li&gt;high ambient density&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;to occur. Normal jets have subsonic exhaust speeds, and only the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/adjustable-area-jet-engine-nozzles/9666#9666&quot;&gt;convergent-divergent nozzle&lt;/a&gt; of afterburning engines can produce the supersonic speed required. Inside the nozzle the air is accelerated by converting pressure into speed in a diffusor, the last part where cross section increases downstream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that supersonic gas has no means of being influenced by what happens downstream. In the nozzle it is easy to accelerate the exhaust gas so much that its pressure drops below 1 bar - just make the end cross section of the diffusor wide enough. When this low-pressure, supersonic jet leaves the nozzle and is confronted with ambient air, the air pressure will compact the jet. This can be seen very well in Russel's lower picture: A shock will form from the circumference of the nozzle and produce a cone which separates the low-pressure core of the exhaust gasses from the downstream section which is affected by air pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now something interesting happens: When the shock waves meet in the middle, the get reflected outwards, and what follows is a sequence of inward- and outward-traveling shocks which form this distinct diamond pattern. That it is visible at all is due to the carbon atoms in the fuel which glow orange because of their heat. The compression shocks originating from the circumference of the nozzle are  reflected at the center, turning into expansion fans when reflected at the boundary of the hot exhaust gasses and ambient air, and become compression shocks again when reflected at the boundary the next time. The compression will heat the flow, igniting remaining fuel and thus intensifying the glow of the carbon atoms, and the expansion will cool it, so you see alternating patterns of bright and dark, separated by the oblique shocks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TXAz6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same happens with rockets at lower, high-density altitudes. Rocket designers have to find a compromise between small, lightweight nozzles which have a high exit pressure (and waste some of the energy in the rocket fuel by not accelerating the exhaust gasses as much as possible) and bigger nozzles which also have lower exit pressure than 1 bar. If the nozzle is optimized for higher altitude and over-expands the exhaust gasses when operated closer to the ground, the same shockwaves become visible. The picture above is from &lt;a href=&quot;http://copenhagensuborbitals.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Copenhagen suborbitals&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-02-07T09:43:38.213" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12456" PostTypeId="2" ParentId="12452" CreationDate="2015-02-06T08:02:43.047" Score="15" Body="&lt;p&gt;The context of this answer is 747-100 and -200 freighters at two airlines during the 1990s flying both civilian and military freight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the 747-100 and -200 you had a 3-man cockpit crew: Captain, First Officer, and Flight Engineer. With the 3-man crew, there was no regulatory need to carry an additional pilot for a long flight. The 747-400 has, of course, a 2-man cockpit, but I don't know what the long-haul regulatory requirement was/is for an additional pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was no regulatory requirement to carry a loadmaster. If you were going between two stations that you regularly operated between, a loadmaster might not be carried if each station had trained loadmasters. However, if you were on a multi-leg, multi-day trip including stops where there wouldn't be loadmasters, one would be on-board (and maybe two if one of them was being trained). The loadmasters sometimes stayed with the airplane (or at least they used to) for periods of a few days to as much as two weeks even though the cockpit crews were changed out every day. Every few days the loadmasters would check into a close hotel for a quick shower or use a shower at an airport maintenance facility or some such. What always dismayed me was that they seemed to exist solely on catered food on the airplane for the entire time. While the airplane was in the air they slept when they weren't eating. Hopefully by now loadmasters are unionized and have better working conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mechanic was often carried if the airplane was having troubles or if it was being dispatched into Africa or other places where competent maintenance would not be available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were carrying horses, there would be handlers with them. The one time I carried horses, they had a handler for each horse. Also, if you were carrying sensitive or very expensive cargo, there would often be someone to watch over it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it was a military cargo flight, there would sometimes be a 'military courier' or two aboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jumpseaters were common, sometimes a lot of them depending on where you going, where you were coming from. The old 747s had 2 jumpseats in the cockpit and, typically, at least 8 first class seats on the upper deck, and often a bunk or two. I noticed in the accident report for the 747 freighter loss at Bagram that there were 7 persons aboard.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-02-06T20:10:25.703" LastActivityDate="2015-02-06T20:10:25.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12458" PostTypeId="1" AcceptedAnswerId="12466" CreationDate="2015-02-06T12:00:53.757" Score="36" ViewCount="20080" Body="&lt;p&gt;According to this image, taken from &lt;a href=&quot;http://www.omao.noaa.gov/aviationsafety/pdf/%28Brickhouse%29The%20Science%20of%20Survivability-1.pdf&quot; rel=&quot;noreferrer&quot;&gt;The Science of Survivability&lt;/a&gt; (Page 79) from NOAA, the statistically safest seats to sit in are at the rear of the plane (69% survival rate vs 49% at the front).&#xA;&lt;img src=&quot;https://i.imgur.com/3m7QNCk.gif&quot; alt=&quot;Aircraft seat survivability&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a business perspective (and ignoring any ethical considerations of whether passengers should pay more for a better chance of survival), it would seem to me to make more sense to put your highest paying and likely most regular passengers in the safest part of the plane, the rear.&#xA;Yet almost exclusively they are placed in the front, the un-safest part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why are First/Business class seats in the un-safer front of the craft and not the safer rear?&lt;/p&gt;&#xA;" OwnerUserId="7201" LastEditorUserId="7201" LastEditDate="2015-02-06T15:20:03.420" LastActivityDate="2018-09-16T17:17:31.080" Title="Why are First/Business Class seats at the front of aircraft where it is the least safe?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;airline-operations&gt;" AnswerCount="8" CommentCount="19" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12459" PostTypeId="2" ParentId="12458" CreationDate="2015-02-06T12:13:15.897" Score="3" Body="&lt;p&gt;In both jets and propeller planes, the section of the plane in front of the engines is generally the quietest. The ride tends to be smoother as you get further away (in either direction) from the wing, too. The common answer that the seats are up there to speed loading and unloading might have been true back in the day, although most airliners still board through a forward door (either the first or second door on the left is most common).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect the real answer has to do with legacy airliners, though: back in the day, first-class seating was in the front, and now it's there because that's where it's always been.&lt;/p&gt;&#xA;" OwnerUserId="7023" LastActivityDate="2015-02-06T12:13:15.897" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12460" PostTypeId="1" AcceptedAnswerId="12479" CreationDate="2015-02-06T12:40:59.080" Score="17" ViewCount="4914" Body="&lt;p&gt;On &lt;a href=&quot;http://www.airliners.net/photo/LOT---Polish/Boeing-767-35D-ER/2137756/&amp;amp;sid=9138edc8a83b494b1f525a778e4280ac&quot; rel=&quot;nofollow noreferrer&quot;&gt;many&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/photo/British-Airways/Aerospatiale-BAC-Concorde-102/0413742/&amp;amp;sid=1005d90cc405f5c7e305ff34ec5766d1&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft&lt;/a&gt; &lt;a href=&quot;http://www.airliners.net/photo/Supermarine-300-Spitfire/2484406/&amp;amp;sid=f0453d37092d74d91758bab19f36ead5&quot; rel=&quot;nofollow noreferrer&quot;&gt;with low wing&lt;/a&gt;, landing gear (either wheel, leg, or both) retracts into the wing. Thus, when deployed, a significant part of the lower surface of the wing is not as clean as when the landing gear is retracted. It must affect aerodynamics by adding drag, but may also affect lift as this modify airflow along the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the aircrafts whose landing gear or landing gear leg retracts underwing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does the landing gear affect aerodynamics when deployed and when deploying? &lt;/li&gt;&#xA;&lt;li&gt;Is it different for aircraft whose landing gear do not retract into the wing?&lt;/li&gt;&#xA;&lt;li&gt;Does this modify performance critical when taking off or landing such as stall speed, optimal climb speed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="22726" LastEditDate="2019-06-12T20:57:25.423" LastActivityDate="2019-06-12T20:57:25.423" Title="How do landing gear retracting into the wing affect performance when deployed?" Tags="&lt;aircraft-performance&gt;&lt;landing-gear&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="12461" PostTypeId="2" ParentId="12458" CreationDate="2015-02-06T13:18:59.480" Score="5" Body="&lt;p&gt;As a high paying passenger what would you prefer, that you need to walk all the way from the front of the aircraft to your seat through a narrow walk way or be able to be seated immediately and not look at the lower class?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rear entry is not used because the wing it in the way of the jetty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting them in front also allows you to call them later so they don't have to wait in their seats as long before departure and lets them wander the gate and spend more in the shops.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-06T13:18:59.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12462" PostTypeId="1" CreationDate="2015-02-06T13:35:55.487" Score="2" ViewCount="396" Body="&lt;p&gt;I was hoping someone could provide me with an estimate of what percentage of aircraft are equipped for RNAV (&lt;a href=&quot;https://en.wikipedia.org/wiki/Area_navigation&quot; rel=&quot;nofollow&quot;&gt;Area Navigation&lt;/a&gt;). I'm more interested in commercial aircraft, but business and general aviation would be nice to know too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is for my own curiosity, so speculation is perfectly fine.&lt;/p&gt;&#xA;" OwnerUserId="7204" LastEditorUserId="2171" LastEditDate="2015-02-06T13:44:57.953" LastActivityDate="2015-06-02T15:01:57.627" Title="Approximately what percentage of aircraft are equipped with RNAV?" Tags="&lt;navigation&gt;&lt;autopilot&gt;&lt;aircraft-systems&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12463" PostTypeId="2" ParentId="12458" CreationDate="2015-02-06T13:40:09.877" Score="79" Body="&lt;p&gt;There are several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/FIFO&quot;&gt;&lt;strong&gt;First In, First Out&lt;/strong&gt;&lt;/a&gt;&lt;br&gt;&#xA;They are given precedence to board the airplane before others, and precedence to disembark the airplane before others too.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Quieter Environment&lt;/strong&gt;&lt;br&gt;&#xA;On commercial airplanes, engines are on the wings which are in the aft of first class. Hence first class is quieter, which is a better experience.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Low Turbulence&lt;/strong&gt;&lt;br&gt;&#xA;Turbulence at the front of the plane is lower than the back. Aircraft are extremely flexible and will bounce around more in the back than the because the bump hits the front and causes the back to vibrate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Seating Arrangement&lt;/strong&gt;&lt;br&gt;&#xA;Important and prominent passengers feel that they should be in the front or on the upper deck (747 or A380), when available. They also feel that they do not need to see other parts of the airplane which are not of their concern.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Marketing Strategy&lt;/strong&gt;&lt;br&gt;&#xA;When economy class people walk through first and/or business class, they will notice the perks and benefits of traveling in these higher classes. They may upgrade their seats on future travels for a higher price.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-06T13:40:09.877" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="12464" PostTypeId="2" ParentId="12458" CreationDate="2015-02-06T13:45:08.510" Score="6" Body="&lt;p&gt;Because, like in so much else, we trade off safety for convenience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why fly at all, if you want to be inconvenienced, but safer? Okay you couldn't get where you're going, but it's (almost) impossible to be involved a plane crash if you aren't on a plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real answer is that statistically, very few people are ever involved in a plane crash. Of those, statistically very few die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated in &lt;a href=&quot;https://aviation.stackexchange.com/a/11671/3945&quot;&gt;my answer here&lt;/a&gt;, if you got on a random plane right now, and then at every airport immediately disembarked and got onto another about to leave, it would take you something between 20 and 100 &lt;strong&gt;million&lt;/strong&gt; flights before you died.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you have a 0.00000001 to 0.00000005 chance of ever dying in a plane crash. That's so close to negligible that it isn't a factor. And if you survive a plane crash, are you really likely to be grateful to your airline for putting you in the nice &quot;ever so slightly safer&quot; seats in the back?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The statistics of the &quot;safer&quot; seats is based purely on accidents which have a proportion of fatalities: it excludes accidents where everyone or nobody dies, and ignores injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, you're looking at a statistically insignificant statistic about which seat is &quot;safest&quot; on a plane that will almost certainly not crash anyway, and even if it did, everyone would be probably be fine (85% of accidents have no fatalities).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare that negligible difference in safety, with the 4.5 &lt;strong&gt;million&lt;/strong&gt; passengers per day, of which approximately half a million (10%) or so are likely business class.... and you're looking at massively inconveniencing 182 million of your best paying, most impatient passengers every year, in exchange for making them ever-so-slightly less likely to die in an accident they probably wouldn't be involved in in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm in a plane crash, I'm probably either dead or not... my concern is not whether I'm going to use my frequent flyer miles, nor where I'm sat.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-02-06T13:53:13.183" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12465" PostTypeId="2" ParentId="12460" CreationDate="2015-02-06T13:58:29.020" Score="2" Body="&lt;p&gt;The main effect of the gear is its drag increase and a pitch-down moment due to the low location of the drag. Since fixed gears usually are more aerodynamic than the struts of a retractable gear, these effects are less pronounced for fixed gears. Another moment change is possible with retraction in flight direction; then gear activation causes a small shift of the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drag increase is highest during gear deployment because the open wheel wells create additional drag. Normally, the drag of the extended gear leg, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8670/is-there-a-best-number-of-wheels-per-bogie/8672#8672&quot;&gt;wheel bogie&lt;/a&gt; and wheels is the biggest part, so the open wheel wells will contribute maybe 30% of the total. Precise values vary wildly, depending on gear location, retraction direction and gear size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect of open landing gear doors on lift is marginal, possibly even beneficial. So in total they lower L/D without affecting minimum airspeed. The higher drag shifts the optimum speeds for minimum sink speed and best cruise to lower values. Note that maximum speed is limited while the gear moves and is down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare the effect on lift to that of a split flap: This also creates a lot of drag and separated flow, but when you &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/arc/rm/2622.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;compare the flap effectivity (pdf!)&lt;/a&gt;, it will give more maximum lift than an equal camber flap. By keeping the upper surface unchanged, a split flap will affect the upper side pressure distribution less and will allow it to contribute more lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/72KMq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, lift is created by deflecting air downwards. If the flow is impeded on the lower side of the wing, this helps with this deflection more than it hinders it. However, this is not an efficient way to increase lift - the drag increase is significant, and for that reason modern landing gear doors stay closed when the gear is not moving, except for those which are blocked by the extended gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, the gear doors stick out in flow direction, so their blocking effect is small and local. Thus, their effect on lift is small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinning wheels will create a gyro effect which will make the aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/3702/why-are-aircraft-tires-not-pre-spun-prior-to-landing-to-preserve-them/3705#3705&quot;&gt;react in funny ways&lt;/a&gt; if the pilot wants to make small adjustments.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-06T20:17:54.717" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12466" PostTypeId="2" ParentId="12458" CreationDate="2015-02-06T14:33:04.910" Score="43" Body="&lt;p&gt;Farhan did an excellent job explaining the answer from a creature comfort perspective, but let me explain why from the standpoint of safety and public perception of said safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, the difference between the front and the back isn't as stark as the red and green colors might imply.  As your graph shows, the survival rate in the front is 49%, and the rear is 69%, and while a 20% gap is significant, it's not like everyone in the front always dies and everyone in the rear always survives.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, planes simply do not crash all that much, and most frequent fliers just aren't worried about dying in a plane crash, so they'd rather the convenience of the front of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, of those who are worried about dying in a crash, most of them are unaware of the fact they are 20% more likely to do so at the front of the craft.  Most people assume that if the plane crashes, they are just going to die.  Thus, they assume moving to another part of the airplane isn't going to help.  Thus, there isn't really any market demand to move 1st class seats to another location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a final thought, I think even knowing the stats, personally, I'd still rather be up front.  I've read of accidents where there were several people near the rear who survived the initial impact and then either &lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot; rel=&quot;noreferrer&quot;&gt;died from exposure&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Korean_Air_Flight_801&quot; rel=&quot;noreferrer&quot;&gt;died from a spreading fire because they were too injured or weak to move&lt;/a&gt;.  Morbid as it is, sometimes I think I'd rather just &quot;get it over with&quot;... &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2018-09-16T02:03:35.543" LastActivityDate="2018-09-16T02:03:35.543" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="12467" PostTypeId="1" AcceptedAnswerId="12468" CreationDate="2015-02-06T15:07:19.137" Score="0" ViewCount="1349" Body="&lt;p&gt;In reference to &lt;a href=&quot;https://en.wikipedia.org/wiki/TransAsia_Airways_Flight_235&quot; rel=&quot;nofollow&quot;&gt;Flight 235&lt;/a&gt;, there is a lot of &lt;a href=&quot;http://www.flightglobal.com/news/articles/transasia-atr-flight-data-suggests-wrong-engine-shut-408774/&quot; rel=&quot;nofollow&quot;&gt;speculation&lt;/a&gt; going on today, and since the flight recorders' data indicate that the running engine was shut down manually, everyone is suspecting that probably the pilots made the mistake to shut down the running engine instead of the faulty engine to attempt a restart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that was the case, why can't there be an alert to warn the pilots that they are shutting down the working engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the software world, we attempt to create so many fail safe situations to avoid letting users mistakenly take an action which will kill the process, why can't that be done for a multi-million dollar aircraft where so many lives are at stake?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S: I know these are all theories and not any official crash investigation reports but I am curious as to how such suggestions can even be made? Even my radios for radio-controlled airplanes provide many fail safe features.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="65" LastEditDate="2015-02-06T15:30:15.473" LastActivityDate="2015-02-06T17:37:30.773" Title="Why is there no alert if shutting down a running engine during flight?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;&lt;accidents&gt;&lt;engine-failure&gt;&lt;accident-investigation&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ClosedDate="2015-02-06T23:51:32.783" ContentLicense="CC BY-SA 3.0" />
  <row Id="12468" PostTypeId="2" ParentId="12467" CreationDate="2015-02-06T15:31:29.127" Score="9" Body="&lt;p&gt;Because in an emergency situation you do not want to stand in the way of the pilot.(*)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whoever designs the system knows that it could fail and it also knows that there are two pilots in the cabin. These pilots have been trained to deal with the emergency, have spent hours and hours in simulators to be ready when something happens, you do not want to treat them as clueless users, you want to treat them as professionals that are doing their jobs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system told them that there was a failure, if it would have been a black/white decision the system could have already shut off the engine, but it did not: it lets trained personnel to asses the situation and act accordingly.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;*: as &lt;a href=&quot;https://aviation.stackexchange.com/users/1696&quot;&gt;fooot&lt;/a&gt; correctly points out, you do not want to annoy the pilots with warnings (remember, you &lt;strong&gt;just&lt;/strong&gt; told them an engine is not working!), they may be tempted to preemptively cancel them, &lt;a href=&quot;http://avherald.com/h?article=43023647/0001&quot; rel=&quot;nofollow noreferrer&quot;&gt;causing them to miss other warnings that are actually important.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-02-06T17:37:30.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12469" PostTypeId="1" AcceptedAnswerId="12471" CreationDate="2015-02-06T15:37:47.017" Score="21" ViewCount="26648" Body="&lt;p&gt;Many aviation &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/6305219/&quot;&gt;discussions&lt;/a&gt; of the &lt;a href=&quot;http://www.bbc.com/news/world-asia-31162351&quot;&gt;TransAsia GE235 accident&lt;/a&gt; include comments like &quot;that was a V&lt;sub&gt;mc&lt;/sub&gt; roll&quot;. What is a V&lt;sub&gt;mc&lt;/sub&gt; roll and how should you avoid it and/or recover from it?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="65" LastEditDate="2015-02-06T19:45:04.277" LastActivityDate="2020-12-14T18:06:11.320" Title="What is a Vmc roll?" Tags="&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12470" PostTypeId="2" ParentId="12469" CreationDate="2015-02-06T15:48:43.520" Score="17" Body="&lt;p&gt;It's more correct to say this is an unintended roll induced by flying at a speed below V&lt;sub&gt;mc&lt;/sub&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;V&lt;sub&gt;mc&lt;/sub&gt; (V=Velocity, mc = &lt;a href=&quot;http://en.wikipedia.org/wiki/Minimum_control_speeds&quot; rel=&quot;noreferrer&quot;&gt;minimum controllable&lt;/a&gt;) is the minimum speed a multi-engine aircraft can remain in control in case of a single engine failure. When an engine quits, thrust is no longer symmetrical. Rudder and a little bit of aileron are used to keep the plane level. E.g. If the left engine quits, the plane has a tendency to yaw left and roll left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effectiveness of control surfaces increases with speed. When the speed drops too low, the control surfaces may be unable to balance the plane even at full deflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots are trained to keep the speed above V&lt;sub&gt;mc&lt;/sub&gt; at all times. For example, during the takeoff roll, it is a bad idea to lift off the runway before the airspeed reaches V&lt;sub&gt;mc&lt;/sub&gt;. If the plane pitches up too much during a climb, its speed may also fall below V&lt;sub&gt;mc&lt;/sub&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-02-07T08:17:09.670" LastActivityDate="2015-02-07T08:17:09.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12471" PostTypeId="2" ParentId="12469" CreationDate="2015-02-06T15:51:26.387" Score="28" Body="&lt;p&gt;I'm sure someone else will come along and give you a better answer with illustrations and everything, but until then, here goes :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multi engine aircraft usually have their engines off to either side of the fuselage. This means that if one engine fails, the other engine will produce what's called asymmetric thrust (one engine is stronger than the other). This in turn, because it's off to the side of the aircraft will cause it to yaw in the direction of the dead engine. Should the dead engine also have its prop windmilling, it'll cause more drag than if the prop blades were turned parallel to the wind and thus aggravate the situation by not only not producing thrust but actually acting as a speed brake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To counteract this and continue flying straight you'd have to apply the aircraft's rudder. The rudder is an airfoil sticking out into the wind in order to yaw the aircraft, thus if the amount of air flowing over it is reduced, the effectiveness of the rudder is reduced. This has the effect that there's a minimum airspeed (i.e. minimum amount of airflow over the rudder) that's enough to allow the rudder to counteract the asymmetric thrust as well as some other properties like engine torque. This speed is called $v_{mc}$, or minimum controllable airspeed (there are actually two of these, one airborne and one on the ground). If speed drops below this airspeed, the plane will start to increase the yaw away from the live engine, to the point where eventually the outer wing produces more lift than the inner wing and the aircraft rolls over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's the $v_{mc}$ roll. Avoiding it is a matter of keeping the airspeed up to maintain rudder authority, and/or reducing thrust to the live engine while regaining airspeed. Further steps, like identifying the failed engine and feathering its prop, as well as flying with a slight bank towards the live engine should be undertaken as well as part of the recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore it's advisable to never turn into the dead engine, as the live engine will make it harder to stop the turn. Turning into the live engine will make it harder to start the turn, but the engine will help you get out of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the engines usually spin in the same direction, the effect of torque differs, the torque of one engine aggravates the situation, where the torque of the others alleviates it, thus $v_{mc}$ is specified as the minimum controllable speed if the latter (known as the critical engine) fails and the prop continues to windmill, i.e. the worst possible aerodynamic scenario in the case of a single engine failure barring an uncontained failure causing damage or otherwise changing the aerodynamic properties of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-02-08T09:48:26.047" LastActivityDate="2015-02-08T09:48:26.047" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12472" PostTypeId="2" ParentId="12467" CreationDate="2015-02-06T15:59:26.417" Score="3" Body="&lt;p&gt;In a previous case where a pilot shut-down the wrong engine, the main recommendations concerned pilot training and clarity of cockpit information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There doesn't seem to have been any desire to develop ever more complex systems that obstruct pilot actions in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.aaib.gov.uk/publications/formal_reports/4_1990_g_obme.cfm&quot; rel=&quot;nofollow noreferrer&quot;&gt;AAIB report on 737 crash at Kegworth, UK 1989&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gsrfL.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/FRmlY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-02-06T15:59:26.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12473" PostTypeId="2" ParentId="12467" CreationDate="2015-02-06T15:59:55.487" Score="3" Body="&lt;p&gt;Voice recorder information is not a conclusive way to tell what may have happened to the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When one engine is lost on a twin, you normally reduce power to the other engine to mitigate yaw imbalance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is certainly possible to create every kind of &quot;warning&quot; system imaginable. The reason aircraft do not have this is because such systems add complexity, cost and weight. Complexity is a bad thing. The more wires and computers you have running around, the more scope there is for errors and problems. Designers generally try to include only things that have significant importance. Remember, the more time a designer spends on &quot;warning systems&quot;, the less time they spend on solving problems like how to make the aircraft more efficient and reliable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the you-are-turning-off-a-running-engine warning is concerned. By the time the warning was received the engine would be off, so it would be post-facto warning--not very useful. Preventing the crew from turning off the engine and forcing them to &quot;confirm&quot; that is what they want to do would add more time to protocol--a very bad thing for that kind of protocol. Also, adding a confirmation system would involve a lot more complexity and probably another button (have you seen the inside of a cockpit?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to describe a scenario. Let's imagine the aircraft has the old confirm-you-want-to-do-this button. The engine is on fire but still running. They need to turn it off. The system now asks them via what? a voice prompt? &quot;Do you really want to turn off a running engine?&quot; So, now they are looking through the hundreds of buttons in the cockpit for the yes-I-really-want-to-turn-the-engine-off button. While they are doing this the aircraft is hurtling towards the ground at 300 mph with an engine on fire. Then they finally find the button and push it, but nothing happens because the circuit to which the button is attached is defective because it only gets tested once every two years, but of course the flight crew does not know this. All they know is they have pushed the button and &lt;em&gt;for some unknown reason&lt;/em&gt; they still can't turn off the engine. Meanwhile the aircraft is hurtling towards the ground at 300 mph with an engine on fire and they have seconds left to figure out what the hell is going on....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to re-iterate what Frederico said above: emergency systems should not get in the way of the pilot, so any system, no matter how &quot;perfect&quot; it is, that prevents the crew from taking control actions because it is second guessing that action is generally looked on as creating more risk, not less risk.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-06T15:59:55.487" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12474" PostTypeId="1" AcceptedAnswerId="12476" CreationDate="2015-02-06T17:09:45.970" Score="10" ViewCount="930" Body="&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=48145bb3&amp;amp;opt=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Aviation Herald&lt;/a&gt; already has an image of the Flight Data Recorder information from the crash of &lt;a href=&quot;https://en.wikipedia.org/wiki/TransAsia_Airways_Flight_235&quot; rel=&quot;nofollow noreferrer&quot;&gt;TransAsia GE235&lt;/a&gt;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AYVsH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AYVsH.jpg&quot; alt=&quot;TransAsia GE235 FDR plot&quot;&gt;&lt;/a&gt;&#xA;(click to enlarge)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have determined that the green lines are for engine 1 and the blue lines are for engine 2, but beyond that, I'm a bit lost. Can someone translate the abbreviations and describe what information each graph is indicating for non-pilots.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="1467" LastEditDate="2015-02-07T15:23:28.097" LastActivityDate="2015-02-08T12:52:03.037" Title="What are the data elements shown on the GE235 flight data recorder (FDR) plot?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12475" PostTypeId="2" ParentId="12460" CreationDate="2015-02-06T17:17:34.300" Score="2" Body="&lt;p&gt;There are a few things to think about here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For one deployed gear basically acts as a speed brake, many new GA planes are working to allow gear extension at full cruise so the gear can double as a speed brake, notable Diamond has done this on their new twin, and talks about it in a few of the videos. So from that stand point they act like any other drag creating air break.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets talk about air flow over the wing. While a wing generates lift as a whole item, the lift is distributed along the length of the wing as is the air flow. Most GA planes (and the war birds you have pictured) have the gear in a more inboard position. Deployed gear may create a bit of turbulent flow on the inner part of the wing but the rest of the wing still generates lift while the gear is down and interrupting air flow, possibly effecting lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for speeds you have Vs0 which is your stall speed in landing configuration which could differ from your Vs but should be confirmed in your POH for each aircraft. I would think from a design stand point the engineers make sure that the wing generates enough lift for take off and landing and safe flight with the gear down but focus mainly on aerodynamics from a gear up perspective as that is the common setup of a plane. You should also note that the drag from the gear will affect climb performance so you will want to get that gear up quickly once you are flying.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="595" LastEditDate="2015-11-27T12:08:47.430" LastActivityDate="2015-11-27T12:08:47.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12476" PostTypeId="2" ParentId="12474" CreationDate="2015-02-06T17:49:31.863" Score="13" Body="&lt;p&gt;From top to bottom:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;main gear&lt;/strong&gt; : whether there is weight-on-wheel not [scale on the left, in blue: &quot;air/gnd&quot;] (thanks to DeltaLima for pointing this out)&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;VHF1&lt;/strong&gt; : probably if there was communication of that radio channel (speculation on my side) [no scale]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Master warning&lt;/strong&gt; : if the MW signal for engine flame out was active or not [scale on the right, in green : &quot;fault/-&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;CLA&lt;/strong&gt; : &lt;a href=&quot;http://www.flightsim.com/vbfs/showthread.php?18991-Turboprop-question-what-are-the-condition-levers-for&quot; rel=&quot;nofollow noreferrer&quot;&gt;Conditioner Lever Angle&lt;/a&gt; [scale on the right, in green : &quot;fuel SO/no FSO&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Beta&lt;/strong&gt; : usually is used to indicate aircraft sideslip, in this case is referring to the propeller blades, 90 degrees signal feathering. [scale on the left, in green : &quot;90//10&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Bleed valve&lt;/strong&gt; : whether it was open or closed (as labeled on the right) [scale on the right, in green : &quot;open/closed&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;PLA&lt;/strong&gt; : power lever angle, aka throttle lever position [scale on the left, in green : &quot;80//30&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;ITT&lt;/strong&gt; : &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-191771.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;inter turbine temperature&lt;/a&gt; [scale on the right, in green : &quot;700//100&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;NP&lt;/strong&gt; : propeller RPMs as % of max RPMs [scale on the left, in green : &quot;100//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Fuel flow&lt;/strong&gt; [scale on the right, in green: &quot;2000//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Objective TQ&lt;/strong&gt;: &lt;a href=&quot;http://www.scribd.com/doc/61626807/ch-2#scribd&quot; rel=&quot;nofollow noreferrer&quot;&gt;objective torque&lt;/a&gt; (*) [scale on the right, in green : &quot;100//80&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;TQ&lt;/strong&gt; : torque [scale on the right, in green : &quot;200//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;NL&lt;/strong&gt; : low pressure shaft RPMs [scale on the left, in green : &quot;100//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;NH&lt;/strong&gt; : high pressure shaft RPMs [scale on the right, in green : &quot;100//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Oil pressure&lt;/strong&gt; [scale on the right, in green : &quot;100//0&quot;]&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Barometric corrected altitude&lt;/strong&gt; [scale on the left, in cyan: &quot;2000//0&quot;]&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;*: from page 2 of that link:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/CZFDQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-02-08T12:52:03.037" LastActivityDate="2015-02-08T12:52:03.037" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12478" PostTypeId="2" ParentId="12375" CreationDate="2015-02-06T18:18:28.893" Score="4" Body="&lt;p&gt;You can use &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flightradar24&lt;/a&gt; which will shows air traffic in real time where you can check which airlines are the busiest. Flightradar24 is using the callsign of the flight and compare it with big databases of airline and airport schedules to find the matching flight number, so not all airlines are submitting their schedules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can choose Airline fleet database in Data/History where you can check a comprehensive guide about the fleets of the world's airlines. Once you select an individual airline to view, you'll get its entire fleet. However it won't give you exact number, but list of all airplanes flying per airline (e.g. &lt;a href=&quot;http://www.flightradar24.com/data/airplanes/easyjet-ezy/&quot; rel=&quot;nofollow noreferrer&quot;&gt;EasyJet&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To display the number, either you should request that information from the author of the site, or there are few workarounds.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Technical analysis of the busiest airline&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you open the page with specific airline (as suggested above, e.g. &lt;a href=&quot;http://www.flightradar24.com/data/airplanes/easyjet-ezy/&quot; rel=&quot;nofollow noreferrer&quot;&gt;EasyJet&lt;/a&gt;), you can type the following command in JS console (e.g. in Chrome - More tools and choose JavaScript Console):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;$(&quot;#listAircrafts li&quot;).length&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;and it'll print you the number of flying planes (sometimes less, because of the pager).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or use &lt;a href=&quot;https://developer.yahoo.com/yql/console/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Yahoo Developer Console&lt;/a&gt; and type the following query:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;select * from html where url=&quot;http://www.flightradar24.com/data/airplanes/ryanair-ryr/&quot; and xpath = '//*[@id=&quot;listAircrafts&quot;]/li'&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;And in Tree View, you'll see number of flying planes at the moment (e.g. &lt;code&gt;count: 323&lt;/code&gt;) based on Flightradar24 database.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To combine all lists together, you need a script as below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In example the following *nix command (it'll take few minutes to run):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;$ time for uri in `curl -s http://www.flightradar24.com/data/airplanes/ | grep -o 'data/airplanes/.*-[^&quot;]*'`; do curl -s http://www.flightradar24.com/$uri | grep -o '/data/airplanes/.*-[^&quot;]*' | wc -l; echo $uri; done | paste -d&quot; &quot; - - | sort -nr | head -n20&#xA;521 data/airplanes/airbus-aib/&#xA;484 data/airplanes/china-southern-airlines-csn/&#xA;411 data/airplanes/china-eastern-airlines-ces/&#xA;404 data/airplanes/lufthansa-dlh/&#xA;341 data/airplanes/air-china-cca/&#xA;324 data/airplanes/ryanair-ryr/&#xA;306 data/airplanes/british-airways-baw/&#xA;259 data/airplanes/turkish-airlines-thy/&#xA;254 data/airplanes/air-france-afr/&#xA;246 data/airplanes/emirates-uae/&#xA;214 data/airplanes/easyjet-ezy/&#xA;193 data/airplanes/saudi-arabian-airlines-sva/&#xA;186 data/airplanes/air-canada-aca/&#xA;184 data/airplanes/air-berlin-ber/&#xA;179 data/airplanes/netjets-nje/&#xA;176 data/airplanes/aeroflot-afl/&#xA;171 data/airplanes/qantas-qfa/&#xA;169 data/airplanes/tam-linhas-aereas-tam/&#xA;163 data/airplanes/cathay-pacific-cpa/&#xA;157 data/airplanes/sas-sas/&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;It will scan over 800 different airlines from the web and it'll print sorted list of the 20 busiest airways according to Flightradar24 database at the time of scanning. Tested on Linux and OSX.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Technical analysis of the busiest route&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to calculate the busiest city to city routes, it's more complex that above example and you'll have to write similar script (or spreadsheet) of fetching all departures/arrivals of each airport (e.g. &lt;a href=&quot;http://www.flightradar24.com/data/airports/LGW&quot; rel=&quot;nofollow noreferrer&quot;&gt;LGW&lt;/a&gt;) from available &lt;a href=&quot;http://www.flightradar24.com/data/airports/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport database over world airports&lt;/a&gt; page, extract data from the tables, consolidate the airport/destination and sum it up in similar way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example extraction from table for &lt;a href=&quot;http://www.flightradar24.com/data/airports/LGW&quot; rel=&quot;nofollow noreferrer&quot;&gt;LGW&lt;/a&gt; airport:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TsXw3.png&quot; alt=&quot;Google Spreadsheet of ImportHtml from LGW airport&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extraction formula which I've used to list all departures from London Gatwick in Google Spreadsheet:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;=ImportHtml(&quot;http://www.flightstats.com/go/weblet?guid=34b64945a69b9cac:4bf2fb3c:1246346ea7d:4597&amp;amp;weblet=status&amp;amp;action=AirportFlightStatus&amp;amp;airportCode=LGW&amp;amp;airportQueryType=0%22&quot;, &quot;table&quot;, 0)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;So theoretically you can extract all departures of the airport per Sheet (&lt;a href=&quot;https://www.google.com/search?q=site%3Ahttp%3A%2F%2Fwww.flightradar24.com%2Fdata%2Fairports%2F&quot; rel=&quot;nofollow noreferrer&quot;&gt;it's like over 3000&lt;/a&gt;), group Destination (so you know at least the busiest destination per airport) and sum it up, do some consolidation between Sheets plus some magic, and viola. That's why it's better to write some script:) If I'd have too much time on hand, of course I could do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in other words, the busiest air route would be the airport which will have the highest number of the same Destination city (if I'm correct).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can always simplify the work by choosing top 20 airports to give you some idea how does it work (instead of checking all of them).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe it won't answer your question directly (which route is the busiest), but it's an idea how to extract the data of the busiest airlines and similar statistics. As it seems it takes a bit knowledge and time how to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you find any easier way of extracting that data or different database, let me know:)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary of the busiest airline&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So based on above data (and ignoring Airbus), it's:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;18:00 UTC/GMT (Friday)&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;China Southern Airlines (484)&lt;/li&gt;&#xA;&lt;li&gt;China Eastern Airlines (411)&lt;/li&gt;&#xA;&lt;li&gt;Lufthansa (404)&lt;/li&gt;&#xA;&lt;li&gt;Air China (341)&lt;/li&gt;&#xA;&lt;li&gt;Ryanair (324)&lt;/li&gt;&#xA;&lt;li&gt;British Airways (306)&lt;/li&gt;&#xA;&lt;li&gt;Turkish Airlines (259)&lt;/li&gt;&#xA;&lt;li&gt;Air France (254)&lt;/li&gt;&#xA;&lt;li&gt;Emirates (246)&lt;/li&gt;&#xA;&lt;li&gt;EasyJet (214)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The data is indicative and it depends on the time of day and week, so I'm not warrant of any correctness of it as this is only the example.&lt;/p&gt;&#xA;" OwnerUserId="2673" LastEditorUserId="2673" LastEditDate="2015-02-07T12:14:00.723" LastActivityDate="2015-02-07T12:14:00.723" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12479" PostTypeId="2" ParentId="12460" CreationDate="2015-02-06T18:56:43.940" Score="13" Body="&lt;p&gt;There are two main geometrical characteristics that affect the airflow in the situation mentioned. From one side you have a cylinder with wheels at the end; on the other side during the transition you have an open cavity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's talk about the first one. You actually have a cylinder flying perpendicular to the air speed. This is kind of canonical problem in fluid dynamics, there is a lot of literature about this problem, but to explain the effect I would like to take a simple example that I took from the website, the infinite 2D cylinder. For that, I include this picture of flow over a cylinder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/egbUL.jpg&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note for fluid dynamics experts: This is not relevant if Reynolds Number (Re) is around 10,000, but for understanding the concept is good enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, imagine that we are cutting landing gear perpendicular to its length and we visualize the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do we see?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two main things....&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Looking at the flow lines, they are almost not affected at 3-4 diameters of distance from the cylinder perpendicular to the flow direction there is a very local influence of the existence of the landing gear.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;However we see that down the flow there is a big influence with the creation of chaotic structures. That is creating a big increase in drag downstream of the landing gear and any surface behind.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Basically... low influence on the red direction and significant influence on blue. Answering your question, influences the wing in a local area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AQdxH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The influence anyhow is negative on the lift, as the flow is accelerated locally, reducing the static pressure below the wing, having a lift reduction, but is a local effect. This also have an influence on the wing lift distribution and a small effect on drag... lower than the one directly produced by the landing gear itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now.... the cavities, they have a bigger influence, firstly because they have bigger extension parallel to the airplane surface (the landing gear goes perpendicular to the airplane the cavity goes along the surface). Secondly, their flow behaviour is different, goes in and outside the cavity. I found this &lt;a href=&quot;http://www.eng.uwo.ca/people/esavory/cavity.htm&quot; rel=&quot;noreferrer&quot;&gt;web page&lt;/a&gt; very good on this, but basically the flow behaviour is like these image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pRzVy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found several flows similar to the second one, but depends on the airplane. You can see that flow will enter and go outside and will have a big influence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the biggest influence is found when the airplane is deploying or retracting the landing gears when you have changing conditions, difficult to predict and affecting the airplane dynamics. Usually you can notice it when landing or taking off, when landing gear is deployed you fell significant vibration on the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning your questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does the landing gear affect aerodynamics when deployed and when deploying?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is a significant drag increase, slightly the lift, but also creates some unsteady behaviour affecting overall airplane mechanics creating vibrations (anyhow, nothing not already taken into account).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it different for aircraft whose landing gear do not retract into the wing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I understand that you refer to airplane with non retractable landing gear. The effect is similar but usually the configuration tries to avoid  having the landing gear close to the wing, as finally they don't need to retract them back.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does this modify performance critical when taking off or landing such as stall speed, optimal climb speed?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Well, stall speed is usually defined by wing lift curve, and not so much affected by the landing gear. Usually the limitation is on the upper side due to separation.&#xA;Climb speed is basically engine thrust minus drag, the drag increases the climb speed is lower. That's why airplanes retract the landing gear as soon as possible.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="3201" LastEditDate="2016-01-22T19:07:22.597" LastActivityDate="2016-01-22T19:07:22.597" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12480" PostTypeId="2" ParentId="12327" CreationDate="2015-02-06T19:19:56.307" Score="0" Body="&lt;p&gt;The data displayed on the client computer depends on the intended use. Different kind of radar displays exist for different kind of Air Traffic Controllers (ATC). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example: VFR controllers, the ones that generally first comes to mind when we think of air traffic controllers, and who primarily direct traffic by looking outside through the tower's glass panes, work directly on airport fields. To assist them in times of low visibility, they generally rely on airport ground surface movement radar (SMR). This allows them to see a general layout of the airport, along with any moving vehicle, airplane or person. Data displayed includes raw digitized video, which is a graphical depiction of the radio wave bouncing off the object, (the blip we often see in war movies), along with an ID tag containing the object's velocity, direction, registration, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other other main branch of ATCs are IFR controllers. They work in enclosed buildings across the country, and need not be close to any airports. Everything they see and hear comes to them through radar and radio links. Their radar display clients do not show the layout of one airport, but rather a portion of an airspace they are responsible for, along with any routes and airways that cross them. Weather is also overlayed (cloud and storm formations), so as not to direct traffic in danger zones. Aircraft tags contain similar data, including transponder code, flight plan number, altitude, etc.&lt;/p&gt;&#xA;" OwnerUserId="7212" LastEditorUserId="572" LastEditDate="2015-04-16T11:21:27.033" LastActivityDate="2015-04-16T11:21:27.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12481" PostTypeId="1" AcceptedAnswerId="12484" CreationDate="2015-02-06T19:29:42.530" Score="10" ViewCount="5596" Body="&lt;p&gt;While selecting random flights to learn about &lt;a href=&quot;http://www.flightradar24.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightRadar24&lt;/a&gt;, I came across &lt;a href=&quot;http://www.flightradar24.com/GGN7311/5752a68&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC7311&lt;/a&gt; flying from &lt;a href=&quot;http://www.airnav.com/airport/CYYZ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Toronto, ON (CYYZ)&lt;/a&gt; to &lt;a href=&quot;http://www.airnav.com/airport/KIND&quot; rel=&quot;nofollow noreferrer&quot;&gt;Indianapolis, IN (KIND)&lt;/a&gt;, and saw that it flew a couple of circles southwest of Lima, OH (near &lt;a href=&quot;http://www.airnav.com/airport/KAOH&quot; rel=&quot;nofollow noreferrer&quot;&gt;KAOH&lt;/a&gt;).&#xA;&lt;img src=&quot;https://i.stack.imgur.com/xcoM5.jpg&quot; alt=&quot;Racetrack!&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some of the reasons Air Traffic Control would direct the pilots to do that?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="1467" LastEditDate="2015-02-06T19:53:09.513" LastActivityDate="2017-02-09T14:19:18.380" Title="Why would a commercal flight circle while enroute?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12482" PostTypeId="2" ParentId="12481" CreationDate="2015-02-06T19:34:21.363" Score="4" Body="&lt;p&gt;It's called &lt;a href=&quot;https://en.wikipedia.org/wiki/Holding_%28aeronautics%29&quot; rel=&quot;nofollow&quot;&gt;Holding Pattern&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC can direct a plane to enter the pattern in order to ensure separation between landings:&#xA;two planes might reach the airport almost at the same time, the first might be directed to land, the second will have to wait.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-02-06T19:34:21.363" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12483" PostTypeId="2" ParentId="12481" CreationDate="2015-02-06T19:41:19.707" Score="1" Body="&lt;p&gt;This maneuver of doing a 360° turn is issued by ATC. There are two reasons for this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;to increase spacing between your flight and another airplane&lt;/li&gt;&#xA;&lt;li&gt;it was one or more circles in a &lt;a href=&quot;http://en.wikipedia.org/wiki/Holding_%28aeronautics%29&quot; rel=&quot;nofollow&quot;&gt;holding pattern&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;By looking at the map, it appears that what your interested flight did was a holding pattern, because it is not &lt;em&gt;too far&lt;/em&gt; to the airport.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-06T19:41:19.707" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12484" PostTypeId="2" ParentId="12481" CreationDate="2015-02-06T20:13:32.120" Score="17" Body="&lt;p&gt;As others have noted, this is called a holding pattern, which is used to delay an aircraft while in the air. Of course, this takes time and fuel, so the system works to prevent this from being necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary use of holding patterns is by ATC to &lt;a href=&quot;https://aviation.stackexchange.com/questions/5235/how-do-airplanes-get-stacked-in-a-holding-pattern&quot;&gt;delay arrivals&lt;/a&gt;. This could for traffic reasons, to delay the aircraft until it can join the line of arriving aircraft. It could also be for facility reasons. Bad weather can reduce the rate at which an airport can accept aircraft, meaning some will have to enter a hold. An airport can also be closed for weather, or for another reason, in which case all aircraft must enter a hold, or land at an alternate airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots sometimes need to use holding patterns as well. If they have an issue with the plane, they may need time to follow their checklists and diagnose the problem. ATC will give them a place to hold for this time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standard arrival procedures generally have holding points published for these cases.  When a holding pattern isn't defined, one can be created. The aircraft will fly for a standard time before turning around, and repeating as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A better FlightRadar example is perhaps the following image, showing three aircraft in the stack and one leaving it&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yI8j3.jpg&quot; alt=&quot;FlightRadar24 showing a Heathrow Stack&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://photozone72.blogspot.co.uk/2013/12/some-random-stuff.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-02-06T21:45:31.390" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12485" PostTypeId="1" CreationDate="2015-02-06T23:11:16.847" Score="9" ViewCount="1397" Body="&lt;p&gt;Do the two old adages of light multi-engine flying, namely &quot;Dead foot, dead engine&quot; and &quot;Raise the dead&quot;, still apply when flying transport-category aircraft?  Or do airline pilots need to rely on their engine instruments in order to figure out which engine's kicked the bucket?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who aren't familiar with those memory aids, they are from page 12-21 (186 in PDF versions) of the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/&quot;&gt;FAA AFM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are two time-tested memory aids the pilot may find useful in dealing &#xA;  with engine-out scenarios. The first, “Dead foot–dead engine” is used to &#xA;  assist in identifying the failed engine. Depending on the failure mode, the &#xA;  pilot won’t be able to consistently identify the failed engine in a timely &#xA;  manner from the engine gauges. In maintaining directional control, however,&#xA;  rudder pressure will be exerted on the side (left or right) of the airplane &#xA;  with the operating engine. Thus, the “dead foot” is on the same side as the &#xA;  “dead engine.” Variations on this saying include “Idle foot–idle engine” and &#xA;  “Working foot–working engine.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The second memory aid has to do with climb &#xA;  performance. The phrase “Raise the dead” is a reminder that the best climb &#xA;  performance is obtained with a very shallow bank, about 2° toward the&#xA;  operating engine. Therefore, the inoperative, or “dead” engine should be&#xA;  “raised” with a very slight bank.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-02-07T00:34:50.863" LastActivityDate="2015-02-07T00:52:39.263" Title="Do airline pilots identify failed engines in the same way as light aircraft pilots?" Tags="&lt;airliner&gt;&lt;flight-training&gt;&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12486" PostTypeId="2" ParentId="12182" CreationDate="2015-02-07T00:19:48.720" Score="3" Body="&lt;p&gt;As ratchet freak mentioned, it is simply not common. Why, you ask?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane aerobatics? Calculated, practiced, somewhat risky, entertaining.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopter aerobatics? Closer to a death wish than airplane aerobatics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamics of helicopters are more complex (think fragile). There aren't as many people willing to do it.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-02-07T00:19:48.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12487" PostTypeId="2" ParentId="12485" CreationDate="2015-02-07T00:52:39.263" Score="16" Body="&lt;p&gt;Yes, the dead foot, dead engine does apply (but not as much as you might think), and, yes, airline pilots need to rely on their engine instruments in order to figure out which engine has failed, especially when you're flying a 4-engine aircraft. Actually, and with obvious prejudice, I prefer to say that the Flight Engineer will use the engine instruments to tell the Captain which engine has failed. Couldn't resist that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sudden loss of power on 727-100s and 747-100s/-200s is not nearly as noticeable as, say, on a Cessna 310. If you lose the middle engine (#2) on a 727, all you're going to notice is the loss of 1/3 of your power. Even the loss of engines 1 or 3 will not produce much yaw because they're mounted close to the aircraft centerline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the transport-category aircraft I flew it was unlikely that your foot would notice an in-flight engine failure because you took your feet off the rudder pedals as soon as you lifted off and didn't put them back on until short final. Adverse yaw was taken care of by the yaw damper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the loss of an engine came during descent at flight idle, the pilots might not notice it unless there is an obvious alert of some kind. We had one quit on us descending into Miami once and neither I nor the f.o. noticed it. Our alert was the f.e. saying something like, &quot;We just lost #3.&quot; My increased work load consisted of simply saying something like, &quot;See if you can get it running again. If it doesn't light off, forget it.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you deliberately shut down an engine, you of course know which engine it is. That happened to me once. Again another vote for f.e.s. This one informed me that the oil pressure was dropping and oil temp climbing on one of the engines. He recommended shutting it down, which we did.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, when you lose an engine suddenly without warning when climbing out, I think the thing to remember is to take your time, fly the airplane with the configuration you have, and work the checklist for the situation at hand. That checklist will have procedures to ensure you shut down the engine that has failed, not one that's still operating. In other words, just do what you do in the sim every 6 months.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-02-07T00:52:39.263" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12488" PostTypeId="2" ParentId="12452" CreationDate="2015-02-07T01:00:53.507" Score="7" Body="&lt;p&gt;Modern civil cargo flights can be divided into three categories: containerized-load, large-load, and feeder.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Containerized-load cargo (ULDs, standard pallet loads)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This is your typical UPS or FedEx flight; their flight crew complements are no different than a passenger aircraft flying the same route -- a captain and F/O for a short haul route such as one of the UPS A300s, and a captain, F/O, relief captain, and relief F/O (&quot;heavy&quot; crew) for a long-haul flight that needs them, although they may prefer to break such a flight up into segments, performing crew changes on the ground.  (Flight engineers aren't counted here since those aircraft are basically retired now.)&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Bulk-load cargo&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;These loads (vehicles, large equipment, live animals, etc) require more attention, so loadmasters are more commonly seen on these flights.  &lt;em&gt;However&lt;/em&gt;, the FAA does not consider a loadmaster &quot;flight crew&quot; in the sense that there are no licenses or ratings for the position; the training and qualifications for loadmasters are completely up to their employer.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Feeder aircraft&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Feeder aircraft are often turboprop types (ATRs, for instance) that are too small to use standard-sized ULDs, so they are loaded in bulk on the main deck.  They use a captain and first officer pairing as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, most cargo aircraft have room for supernumeraries (aka jump seaters), at least on the cockpit jumpseats if not in a forward or upper deck passenger cabin as well; long-haul aircraft will also have crew rest bunks fitted to that forward cabin area for use by &quot;heavy&quot; crews.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-02-07T01:00:53.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12489" PostTypeId="2" ParentId="12469" CreationDate="2015-02-07T03:14:15.937" Score="0" Body="&lt;p&gt;The Vmc roll, specifically, is a rapid &lt;strong&gt;roll&lt;/strong&gt; (not yaw) below Vmc. It occurs primarily because a thrusting engine located on a wing decreases the stall speed significantly. Therefore, as airspeed decreases, a moment occurs when the wing with non-thrusting engine stalls, while the other wing continues to produce lift. At that point the airplane quickly rolls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that 1) for this asymmetry to happen you need a rather small amounts of thrust, and 2) the stall speed of one wing grows. So, if you think that you made it once the trottle is cut and the rudder deflection is way down, and try to fly a usual landing, then you will die. See this:&#xA; &lt;a href=&quot;https://www.youtube.com/watch?v=YZIzEtHzbNU&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=YZIzEtHzbNU&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why all the yaw-centered explanations of Vmc roll are hazardous and you should reject them as soon as possible. It's not yaw that will kill you, it's the roll -- and it can happen from a minimal yaw.&lt;/p&gt;&#xA;" OwnerUserId="3982" LastActivityDate="2015-02-07T03:14:15.937" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12490" PostTypeId="2" ParentId="12365" CreationDate="2015-02-07T03:38:17.600" Score="3" Body="&lt;p&gt;Joining engines has been attempted in the past in the straight-turbojet days -- the Iluyshin Il-62 and the Vickers VC-10 used this configuration, and so did the Lockheed JetStar business jet; this was done due to the poor thrust output of early turbojets.  Modern turbofans crank out enough thrust that you don't need to pair up engines -- in fact, one proposal was floated for the USAF to replace the paired turbojets on the B-52's engine pylons with single RB-211 turbofans (thus turning an eight-turbojet-engine bomber into a four-turbofan-engine one).  This was rejected due to the upfront costs; however, the fuel savings would have been quite significant due to both the ability to use half as many engines &lt;em&gt;and&lt;/em&gt; the improved specific fuel consumption of the turbofans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue with paired engines on a pylon is safety -- &lt;a href=&quot;http://en.wikipedia.org/wiki/LOT_Flight_5055&quot; rel=&quot;nofollow&quot;&gt;LOT 5055&lt;/a&gt; demonstrated this in tragic fashion when one of its Soloviev D-30 turbofans suffered an uncontained failure, causing an engine fire and severe damage to the other engine on that side; had the Il-62 used a more traditional layout, such an incident would have been much less problematic as the fire and damage pattern would have been much more confined.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-02-07T03:38:17.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12492" PostTypeId="1" CreationDate="2015-02-07T04:47:41.303" Score="7" ViewCount="2921" Body="&lt;p&gt;I recently found out that the little protective rails over the toggle switches in the space shuttle were made out of titanium.  I'm not sure of which alloy specifically, but probably 6AL4V (or &quot;Grade 5&quot;).  I heard rumors that the covers for each switch cost near $800 (USD).  Titanium is heavier than aluminum, so what was the reasoning for using it to make the switch covers? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All I can think of, is in the event of a crash the titanium would better protect the switches than aluminum...  But I'm not sure how high that is on their list of concerns in the event of a crash, or similar event. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7cXui.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2015-02-07T06:03:51.357" LastActivityDate="2015-02-07T06:03:51.357" Title="Why were the toggle switch guards in the Space Shuttle titanium?" Tags="&lt;nasa&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2015-02-07T16:51:34.780" ContentLicense="CC BY-SA 3.0" />
  <row Id="12493" PostTypeId="1" AcceptedAnswerId="12495" CreationDate="2015-02-07T06:03:04.160" Score="5" ViewCount="59320" Body="&lt;p&gt;Is there a standard maximum altitude which skydiving planes can fly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am mainly asking about the sports activity, not military parachuting.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2016-06-14T17:06:50.470" LastActivityDate="2018-11-02T17:21:17.053" Title="What is the maximum altitude a skydiving plane can fly?" Tags="&lt;altitude&gt;&lt;skydiving&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12494" PostTypeId="1" AcceptedAnswerId="12497" CreationDate="2015-02-07T06:30:33.930" Score="4" ViewCount="7889" Body="&lt;p&gt;To work as an FAA controller, you &lt;a href=&quot;https://www.faa.gov/jobs/career_fields/aviation_careers/&quot; rel=&quot;nofollow&quot;&gt;must be a U.S. citizen&lt;/a&gt;. To work as a EUROCONTROL controller, you &lt;a href=&quot;https://www.eurocontrol.int/faq/air-traffic-controller-jobs&quot; rel=&quot;nofollow&quot;&gt;must be a national of one of their member states&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per standard governmental employment laws, I assume most countries around the world have similar requirements. &lt;strong&gt;Are there any exceptions? Are there any places more open to employment of foreign controllers?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are a few U.S.companies that perform contract air traffic control services in other countries, such as &lt;a href=&quot;http://www.rvainc.net/&quot; rel=&quot;nofollow&quot;&gt;RVA&lt;/a&gt;, &lt;a href=&quot;http://www.atctower.com/ATC.aspx&quot; rel=&quot;nofollow&quot;&gt;Midwest ATC&lt;/a&gt;, and &lt;a href=&quot;http://www.serco-na.com/market-segments/transportation/aviation-operations-and-management&quot; rel=&quot;nofollow&quot;&gt;Serco&lt;/a&gt;, but I believe this is mostly for the U.S. Department of Defense. &lt;strong&gt;Are there any countries that have foreign contracts for civilian ATC services?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-03-09T19:44:18.970" Title="Where in the world is it possible to be a foreign air traffic controller (non-military)?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12495" PostTypeId="2" ParentId="12493" CreationDate="2015-02-07T08:07:28.893" Score="11" Body="&lt;p&gt;Qualifier: I am a master parachute rigger and taught sport skydiving for 10 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standard jump altitude is 12,000 feet AGL - this is one turn of the standard parachutist's altimeter. This height provides 1 minute of freefall, is within reach of a Cessna with a decent engine and does not require supplementary oxygen. For most places, this means an operating altitude between 12,000 and 15,000 feet MSL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dropzones in high areas like Denver will reduce their jump altitude to 9,500 feet AGL mainly because the piston-powered planes take too long to climb higher and/or the upper part of the climb runs into the oxygen zone.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-02-07T08:07:28.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12496" PostTypeId="1" AcceptedAnswerId="12584" CreationDate="2015-02-07T10:54:31.623" Score="4" ViewCount="1329" Body="&lt;p&gt;If there is a hijack situation and the terrorist guy shoots at the cockpit door to go inside, will that work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the cockpit door locks in commercial planes like 737s etc good enough to handle a bullet shot?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="97" LastEditDate="2015-02-17T03:48:52.057" LastActivityDate="2015-02-17T03:48:52.057" Title="Can a bullet hit make the cockpit door open?" Tags="&lt;airliner&gt;&lt;security&gt;&lt;cockpit&gt;&lt;terrorism&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12497" PostTypeId="2" ParentId="12494" CreationDate="2015-02-07T11:04:01.940" Score="4" Body="&lt;p&gt;The EUROCONTROL example you give, allows controllers from all member states to work in Maastricht Upper Area Control (Netherlands) and provide ATC over Belgium, (part of) Germany, Luxembourg and the Netherlands. Many of the controllers there are not from any of these four countries so they are foreign air traffic controllers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also EUROCONTROL is only providing Upper Area Control above the four countries mentioned above. All member states have their own Air Traffic Control providers, some have more than one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Within EU countries (note that not all EUROCONTROL member states are EU member states) we have freedom of labour movement. So for EU citizens there should be no official barriers to work as a foreign controller in another EU member state. Apart from the intra-EU rules, some ATC organisation within the EU are open to applications from outside the EU. For example the Dutch Air Traffic Control Organisation LVNL is open to &lt;a href=&quot;https://www.luchtverkeersleider.nl/english&quot; rel=&quot;nofollow&quot;&gt;foreign controllers&lt;/a&gt;. Applicants are not limited to citizens of EU countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC at airports is becoming a commercial business. The companies that you mentioned provide civil ATC at various airports around the world. Another example is ATC at London Gatwick Airport: the contract was &lt;a href=&quot;http://www.airtrafficmanagement.net/2014/07/germanys-dfs-beats-nats-on-lgw-bid/&quot; rel=&quot;nofollow&quot;&gt;awarded to a subsidiary of the German ATC organisation DFS&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside the EU I know that there are many foreign controllers work in the United Arab Emirates. They are looking for &lt;a href=&quot;http://jobs.flightglobal.com/job/1401410196/air-traffic-control-officer-atco-radar-/&quot; rel=&quot;nofollow&quot;&gt;new applications&lt;/a&gt; at this moment as well. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-02-07T11:10:59.050" LastActivityDate="2015-02-07T11:10:59.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12498" PostTypeId="2" ParentId="12182" CreationDate="2015-02-07T12:57:35.963" Score="4" Body="&lt;p&gt;First off, the reasons you don't see real helicopters performing literally like that model are that it's impossible to get anything like that power-to-weight ratio on a full-size machine and also because the pilot would black out from the ridiculous G's being pulled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why you don't see a whole lot of... less ambitious acrobatic flying in helicopters, it's possible that certification is an issue.  For example, the &lt;a href=&quot;https://www.youtube.com/watch?v=j-piEL58hsg&quot; rel=&quot;nofollow&quot;&gt;British Army Lynx display&lt;/a&gt; includes rolls, loops and even back-flips. However, I distinctly remember commentary at an airshow I attended saying that, when the Lynx is retired fairly soon, its replacement won't be certified for any kind of acrobatics.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-02-07T12:57:35.963" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12500" PostTypeId="1" AcceptedAnswerId="12501" CreationDate="2015-02-07T14:16:49.513" Score="12" ViewCount="2448" Body="&lt;p&gt;According to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Hughes_H-4_Hercules&quot;&gt;wikipedia&lt;/a&gt; article the Hughes H-4 Hercules (Spruce Goose) reached a maximum altitude of 70 feet on its flight.  At this altitude the aircraft was still in ground effect.  Would the H-4 have been capable of flying out of ground effect?  Why or why not?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2017-08-18T10:49:54.150" Title="Was the Hughes H-4 Hercules capable of flying out of ground effect?" Tags="&lt;aircraft-performance&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12501" PostTypeId="2" ParentId="12500" CreationDate="2015-02-07T14:39:34.987" Score="18" Body="&lt;p&gt;The answer can only be given by comparing it to other, &lt;a href=&quot;https://www.youtube.com/watch?v=Y22F9O3A0EM&quot; rel=&quot;noreferrer&quot;&gt;broadly similar aircraft&lt;/a&gt;. My three references would be the British &lt;a href=&quot;http://www.aviastar.org/air/england/saunders_princess.php&quot; rel=&quot;noreferrer&quot;&gt;Saunders-Roe Princess&lt;/a&gt;, the &lt;a href=&quot;http://www.flugzeuginfo.net/acdata_php/acdata_jrmmars_en.php&quot; rel=&quot;noreferrer&quot;&gt;Martin Mars&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_314_Clipper&quot; rel=&quot;noreferrer&quot;&gt;Boeing 314 Clipper&lt;/a&gt;, all three at their time huge flying boats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h9WSM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the H-4 has the highest wing area relative to its installed power and its intended maximum take-off mass (MTOW), but does not look totally out of the range of the two smaller specimen. The Princess was conceived as a pressurized airliner and is of a more advanced design than the other three. With the lower wing loading come lower speeds, so the lower power loading looks adequate. &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_323&quot; rel=&quot;noreferrer&quot;&gt;Another huge military transport plane of that time&lt;/a&gt; which was derived from a cargo glider (the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_321&quot; rel=&quot;noreferrer&quot;&gt;initial requirements&lt;/a&gt; asked for a cargo volume equivalent to a &lt;a href=&quot;http://en.wikipedia.org/wiki/Deutsche_Reichsbahn&quot; rel=&quot;noreferrer&quot;&gt;Reichsbahn&lt;/a&gt; standard &lt;a href=&quot;http://en.wikipedia.org/wiki/German_state_railway_norms&quot; rel=&quot;noreferrer&quot;&gt;cargo wagon&lt;/a&gt;) had a wing loading of just 150 kg/m², a very similar power loading of 23.56 HP/m² and flew just fine. Stick forces were massive, however, and stability was marginal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exact performance would depend on details like airfoils, aspect ratio, flap settings, hull design and stability, but in general it looks as if the H-4 would have been capable of flying out of ground effect. But its performance would not have been spectacular - a little more installed power would had made it better.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-08-18T10:49:54.150" LastActivityDate="2017-08-18T10:49:54.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12502" PostTypeId="1" AcceptedAnswerId="12505" CreationDate="2015-02-07T15:54:00.080" Score="14" ViewCount="1558" Body="&lt;p&gt;Many aviation careers have mandatory retirement ages.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/licenses_certificates/airmen_certification/pilot_age_65/&quot;&gt;Airline Pilot (licensed with FAA)&lt;/a&gt;: 65 (raised from age 60 a few years ago)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_controller#Age_restrictions&quot;&gt;Controller&lt;/a&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FAA: 56&lt;/li&gt;&#xA;&lt;li&gt;NATS: 60&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Why do these age limits exist?&lt;/em&gt; Is it a matter of increasing risk (even when one is healthy) of becoming incapacitated while on the job (heart-atack, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="62" LastEditDate="2015-02-07T17:33:50.277" LastActivityDate="2015-02-07T18:57:28.917" Title="Why do aviation careers have age limits?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;medical&gt;&lt;pilots&gt;&lt;career&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12503" PostTypeId="1" CreationDate="2015-02-07T17:14:03.833" Score="20" ViewCount="9317" Body="&lt;p&gt;&lt;em&gt;Many airports have more than one runway. How should runways be built in order to achieve maximum usage and minimum delays?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Many major airports have most, if not all, parallel runways. Examples include LAX, DFW, and ATL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, &lt;a href=&quot;http://www.faa.gov/airports/airport_development/omp/faq/runway_utilization/&quot; rel=&quot;noreferrer&quot;&gt;Chicago O'Hare has been undergoing some major runway improvements&lt;/a&gt;, mainly to make the runways more parallel. This figure shows the before (mid-2000s) and after (completion date TBD) layout of ORD. Eventually, ORD is slated to have 6 parallel E-W runways, along with 2 SW-NE runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uexhC.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a crossing configuration is very common at airports with only 2 runways. Here is one example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CTaqF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are parallel runways more efficient, and smaller airports simply don't have space for them? &lt;strong&gt;Ideally, how should runways be configured?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Edit:&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Additionally, what if we assume...&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Case 1 - That wind isn't a factor?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Case 2 - That the airport location has exceptionally variable winds?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Case 3 - That space/airport footprint is an issue?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="22726" LastEditDate="2018-06-05T17:50:43.920" LastActivityDate="2018-06-05T17:50:43.920" Title="What are the most efficient layouts of multiple runways?" Tags="&lt;airport&gt;&lt;runways&gt;&lt;separation&gt;&lt;parallel-runways&gt;&lt;intersecting-runways&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12505" PostTypeId="2" ParentId="12502" CreationDate="2015-02-07T17:32:16.853" Score="14" Body="&lt;p&gt;I'm no expert, but I can think of two general reasons: risk of incapacitation, and general physical limitations (reaction speed, stamina, the ability to maintain concentration for extended periods etc.). The age 65 limit only applies to part 121 ATP pilots, by the way; you can still be a commercial or private pilot for as long as you can keep getting a valid medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older people are simply at &lt;a href=&quot;https://www.heart.org/idc/groups/heart-public/@wcm/@sop/@smd/documents/downloadable/ucm_449846.pdf&quot;&gt;greater risk of heart attacks&lt;/a&gt; and many other medical conditions, and they're also much more likely to require medication that may not be approved by the FAA or other national authorities. Of course that doesn't mean that every older pilot is the same but I guess that the FAA has decided that since the risks increase with age, at some point they become unacceptable. To understand the specific reasons for that decision you would probably need to dig up the original &lt;a href=&quot;http://en.wikipedia.org/wiki/Notice_of_proposed_rulemaking&quot;&gt;NPRM&lt;/a&gt; or transcripts of the public debate/hearings, but I have no idea if that's possible or not. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then the other aspect is general physical and mental condition. They both deteriorate with age, and the NTSB sometimes &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20120916X71751&amp;amp;key=1&amp;amp;queryId=d29998db-f582-447d-aee4-3f71425f10ad&amp;amp;pgno=1&amp;amp;pgsize=50&quot;&gt;mentions that&lt;/a&gt; as a potential factor in accidents:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On the day of the accident, the pilot had flown several formation&#xA;  sorties. The day was hot, and the formation activities were demanding.&#xA;  The accident flight was relatively long, and the co-owner of the&#xA;  airplane guessed it was about 45 minutes long. Most formation sorties&#xA;  were 30 minutes or less. The accident pilot was in his early 70s and&#xA;  was by far the oldest member of the flight. Due to the pilot’s age,&#xA;  the demanding schedule, and the length of the formation sorties,&#xA;  fatigue could have been a factor, although it could not be&#xA;  conclusively determined.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course, any discussion like this is a generalization and I'm sure it's easy to find individual 70-year old pilots or controllers who are 'sharper' than younger ones (after all, experience counts for a lot too). But there's no escaping the overall pattern that older people &lt;em&gt;in general&lt;/em&gt; are more prone to medical issues and less physically/mentally capable than younger ones, and at least one US court &lt;a href=&quot;http://www.nbaa.org/admin/personnel/age-60/20140502-federal-court-mandatory-retirement-age-for-pilots-is-not-age-discrimination.php&quot;&gt;has ruled&lt;/a&gt; that there's no effective way to determine individual risk so a general rule is not discriminatory:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The court also concluded that ExxonMobil had established, through the&#xA;  testimony of several medical experts, that the risk of sudden&#xA;  incapacitation in flight significantly increased with age, and that&#xA;  there are no adequate means of individually testing each pilot to&#xA;  determine whether a pilot was at risk to suffer such an&#xA;  incapacitation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-07T17:32:16.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12506" PostTypeId="2" ParentId="12503" CreationDate="2015-02-07T17:58:03.430" Score="14" Body="&lt;p&gt;In order to increase the number of operations that can be handled at a runway, you want them configured so as to allow &quot;simultaneous independent approaches,&quot; which means that the 2 (or more) runways can be operational without the need to coordinate between them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest factor is the distance between the two runways. The greater the distance between them, the less impact they have on each other, not just in terms of number of operations per hour, but also in terms of visibility minima for instrument approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other factor that needs to be considered is the wind, and as you can see from the Chicago airport layout, there are parallel groups of runways that effectively form a triangle, such that there is never a crosswind component that exceeds 30 degrees. The layout at Las Cruces, NM, which is usually very windy, shows the format better than Chicago, even though they are single runways:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cw0f1.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last issue is the type of radar available, and the faster the radar sweep, the less delay there is between the position of the aircraft and their depiction on the radar screen, allowing the controllers to closely monitor the approaches.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-07T18:26:23.263" LastActivityDate="2015-02-07T18:26:23.263" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12507" PostTypeId="1" AcceptedAnswerId="12511" CreationDate="2015-02-07T18:07:58.100" Score="21" ViewCount="6629" Body="&lt;p&gt;I've heard that most planes (&lt;a href=&quot;https://aviation.stackexchange.com/q/8049/755&quot;&gt;excepting fighter jets&lt;/a&gt;) are &quot;aerodynamically stable.&quot; What does that mean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you're cursing around in a Cessna 172 without autopilot, and you take your hands off the controls. What happens?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Will the plane stay at the same pitch and avoid stalls and dives?&lt;/li&gt;&#xA;&lt;li&gt;Will it stay at the same altitude?&lt;/li&gt;&#xA;&lt;li&gt;Will it say at the same heading?&lt;/li&gt;&#xA;&lt;li&gt;Will it correct each of these as the plane is buffeted by turbulence?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="23223" LastEditDate="2019-08-06T12:26:10.740" LastActivityDate="2019-08-06T12:26:10.740" Title="What does it mean for a plane to be aerodynamically stable?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12508" PostTypeId="1" CreationDate="2015-02-07T18:39:04.217" Score="0" ViewCount="77" Body="&lt;p&gt;I think this is an okay place to ask this. Let me know if it is not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In about a month, my school is going on a school trip and the plane ride is going to be around 15 hours. I was think about setting up a small network on the plane so that we can chat on a locally hosted program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would do this by bringing a small router and hooking it up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this against the rules of most airlines and do you think I could get in trouble?&lt;/p&gt;&#xA;" OwnerUserId="7222" LastEditorUserId="247" LastEditDate="2015-02-08T10:09:02.133" LastActivityDate="2015-02-08T10:09:02.133" Title="Routers on airplanes" Tags="&lt;airlines&gt;&lt;regulations&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2015-02-07T19:31:46.310" ContentLicense="CC BY-SA 3.0" />
  <row Id="12509" PostTypeId="2" ParentId="12507" CreationDate="2015-02-07T18:43:45.380" Score="12" Body="&lt;p&gt;Your guesses are pretty correct - an &quot;aerodynamically stable&quot; aircraft tends to stay (relatively) straight and level if the controls are let go.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Pitch&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Let's say the aircraft's elevator is trimmed to fly level (maintaining the same altitude). You push on the yoke to lower the nose, then release the pressure on the control. The nose-down altitude allows the aircraft to pick up more speed. As speed increases, the wing generates more lift, and the aircraft slowly pitches up. If you pull on the yoke then let go, the nose-up altitude will slow the plane down, which reduces lift. When lift is reduced, the nose drops, picking up speed. A similar argument applies if the plane's pitch is altered by a gust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This stability is called &lt;strong&gt;Longitudinal Stability&lt;/strong&gt;. It is closely related to the forward/aft position of the Center of Gravity (CG). An aircraft with an aft CG has less longitudinal stability.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Roll&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Similarly, the ability of the plane to level its wings when banked is called &lt;strong&gt;Lateral Stability&lt;/strong&gt;. If you roll the plane right 10 degrees then let go, it has a tendency to slowly roll left, going 7 degrees right, 5 degrees right, eventually to almost level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Dihedral_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;Wing Dihedral&lt;/a&gt;&lt;/strong&gt; is a design which adds lateral stability.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/LBOeO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Yaw&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This is called &lt;strong&gt;Directional Stability&lt;/strong&gt;. Similar to pitch and roll, it is the tendency for an airplane to recover from a disturbance in the yawing plane.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Stability vs maneuverability&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The more stable an aircraft is, the less maneuverable. This is a natural trade-off following the laws of physics. Cessna 172s are very stable, suitable for student pilots. But you can't make a Cessna 172 do very rapid changes. Aerobatic aircrafts and fighter jets can respond to pilot inputs very rapidly, but controlling one requires much more skill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*On single engine propeller planes like the Cessna 172, the torque spinning the propeller (&lt;a href=&quot;https://aviation.stackexchange.com/questions/9153/why-do-most-single-propellers-have-a-clockwise-rotation&quot;&gt;usually clockwise&lt;/a&gt;) tends to roll the aircraft counterclockwise (i.e. left) if the controls are fully released. This is due to the &quot;action and reaction&quot; physics principle.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-02-07T19:24:41.803" LastActivityDate="2015-02-07T19:24:41.803" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12511" PostTypeId="2" ParentId="12507" CreationDate="2015-02-07T20:06:45.210" Score="23" Body="&lt;h2&gt;Static stability&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;is the tendency of a system to return to its initial state after a disturbance. Typical disturbances in case of airplanes are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flying into a vertical or horizontal gust&lt;/li&gt;&#xA;&lt;li&gt;A jerk on the stick&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The classic explanation is with a ball sitting in a pit. Whenever its position is changed by a disturbance, it will roll back towards the center. This does not mean that it will stop there - in an ideal world free of friction it will keep moving back and forth like a pendulum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vpASv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is static stability. Broadly speaking, static stability is achieved by placing the center of gravity ahead of the neutral point, the point in which all additional forces due to a change in angle of attack can be summarized. There are two neutral points, one for longitudinal stability and one for directional stability. In both cases the change in angle of attack or sideslip will create a correcting moment around the center of gravity, pulling the aircraft back on its old path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even altitude stability can be achieved, but here we take advantage of the fact that air becomes less dense the higher you climb. If the aircraft is trimmed for horizontal flight at a certain altitude, an altitude change will mean that the power setting does no longer match drag at this new altitude. The aircraft will either climb or sink, depending on the altitude change, until the old altitude has been reached again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases you will experience overshoots and oscillations around the trim point. It can even happen that these overshoots become worse the longer the oscillation lasts (the &lt;a href=&quot;https://en.wikipedia.org/wiki/Phugoid&quot; rel=&quot;nofollow noreferrer&quot;&gt;phugoid motion&lt;/a&gt; in a glider is a good example). To stop the oscillations, you need to add&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Dynamic stability&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;which describes the behavior of the aircraft over time. In most cases, friction will ensure that motions die down, and sometimes aircraft need little helpers like &lt;a href=&quot;https://aviation.stackexchange.com/questions/6391/what-is-the-yaw-damper&quot;&gt;yaw dampers&lt;/a&gt; to get those under control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You mention stalls and dives: They can indeed occur in a statically stable airplane. Low drag means low damping, therefore many high performance gliders have a dynamically unstable &lt;a href=&quot;http://en.wikipedia.org/wiki/Phugoid&quot; rel=&quot;nofollow noreferrer&quot;&gt;phugoid&lt;/a&gt; motion. I know, Wikipedia spells this wrongly, but the explanation is OK, so I linked it nonetheless. If you wait long enough after an initial upset, the oscillations will become so severe that the aircraft stalls at the upmost point of the cycle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you keep enough altitude and have no traffic nearby, this is fun to try.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Spiral dive&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Note that I omitted to say something about roll stability so far. The glider (and your Cessna 172) will also start to roll, and in many cases the roll motion will increase more quickly than the phugoid, so you might need to try several times before you get a phugoid-induced stall. Most aircraft have a weak tendency to increase roll angle and to eventually fall into a &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_dynamic_modes#Spiraling&quot; rel=&quot;nofollow noreferrer&quot;&gt;spiral dive&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no aerodynamic mechanism to right the aircraft up after a roll disturbance. Sorry, @kevin, but dihedral won't help - it only works in case of sideslip.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="23223" LastEditDate="2019-08-06T11:53:05.633" LastActivityDate="2019-08-06T11:53:05.633" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="12512" PostTypeId="2" ParentId="12507" CreationDate="2015-02-07T20:09:35.123" Score="0" Body="&lt;p&gt;Stability has a number of definitions from a control system perspective, but most boil down to a system not doing anything 'unexpected'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to be clear in the following, pitch, roll, yaw refer to angles &lt;strong&gt;not&lt;/strong&gt; rate of change of angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Roll tends to be stable because there is a feedback mechanism (dihedral, or low COG) as Kevin's answer points out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitch &amp;amp; yaw tend to be stable because the rudder/elevator are at the rear (or high wing loading for a canard) which provides a feedback mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without feedback (such as from the pilot or autopilot) no matter how well you have&#xA;trimmed the aircraft, external noise (pressure, air density, changing wind, fuel burnoff, loud cursing, etc.) will result in some slight climb/descent and turn. This is because it is (i) difficult to get the pitch, yaw, roll to be &lt;strong&gt;exactly&lt;/strong&gt; what you want and (ii) things change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you are checking your map during a flight, things will remain mostly the same for a while.&#xA;Of course, this depends on the aircraft, and what options you have to trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broadly, there is a trade-off between stable and manoeuvrable (Bode integral).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 172 will take longer to diverge from straight and level, a Pitt's Special will take your eyes out of the cockpit faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft are inherently unstable and rely on control systems to make the overall system stable. This obviously requires more redundancy &amp;amp; complexity and&#xA;is not found in GA/commercial aircraft. (The following article is technical and focuses on control not aviation, but brings some sobering lessons to design:  &quot;Respect the unstable&quot;, G. Stein, IEEE Control Systems Magazine, August 2003.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft are stable, but the system response is slow and a control system&#xA;(such as a yaw-damper and the various sensors/actuators) are used to provide a &#xA;more docile flight regime.&lt;/p&gt;&#xA;" OwnerUserId="3212" LastEditorUserId="3212" LastEditDate="2015-02-07T20:22:02.487" LastActivityDate="2015-02-07T20:22:02.487" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12513" PostTypeId="2" ParentId="2608" CreationDate="2015-02-07T21:03:45.957" Score="3" Body="&lt;p&gt;It's a 3 layer color system with white opaque special laser colour, a black light block layer, and the final colour. For military it stays black without the 3rd one. After spray painting the special laser color is removed with a laser system. You can see it &lt;a href=&quot;http://youtu.be/-g4lvXXOQME?t=1m2s&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7225" LastEditorUserId="1696" LastEditDate="2015-02-07T21:25:29.040" LastActivityDate="2015-02-07T21:25:29.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12514" PostTypeId="2" ParentId="12474" CreationDate="2015-02-08T00:36:26.357" Score="2" Body="&lt;p&gt;Main Gear (A/G) is the signal of air/ground detecting solenoid that is in the main gear strut AFAIK, it detects when the aircraft is airborne and actuates several different systems that have different behavior while in flight than while on ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not Gear UP/DOWN condition, in most FDRs gear position are 3 different signals one for each gear.&lt;/p&gt;&#xA;" OwnerUserId="7231" LastActivityDate="2015-02-08T00:36:26.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12515" PostTypeId="1" AcceptedAnswerId="12526" CreationDate="2015-02-08T00:55:51.167" Score="13" ViewCount="3924" Body="&lt;p&gt;According to &lt;a href=&quot;https://aviation.stackexchange.com/a/12511/973&quot;&gt;https://aviation.stackexchange.com/a/12511/973&lt;/a&gt; it is not possible for a plane to aerodynamically recover from a roll disturbance.  Is that an inherent limitation of how planes could be constructed, or is that merely a design trait that is accepted in exchange for other considerations like fuel economy and ease of control?  Would it be possible to construct a plane such that if the controls were eased into a certain setting, the plane would settle into a stable spiral climb until it reached an equilibrium altitude set by the thinning air, and such that mild disturbances in the roll axis would settle out [possibly changing the plane's heading]?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would expect that maintenance of roll stability during straight and level flight would be complicated by the fact that roll won't immediately affect the flow of air over a plane in the same way as would a change in pitch or yaw.  If a plane was flying in deliberate circles, however, I would think that a change in roll would rather quickly change the rate at which the plane would want to rotate about the yaw axis, and that aerodynamic surfaces cause such change to produce torque about the roll axis, thus counteracting the disturbance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My intuition would suggest that even if roll stability could be achieved, a plane designed for such stability would probably be annoying to fly in normal usage.  If, however, it was possible to activate a control which would induce such stability, it would seem such a thing might be helpful in some situations where a pilot might otherwise be in trouble [e.g. unexpected sudden IMC or other conditions causing loss of visual horizon reference].  Would such a thing be aerodynamically impossible, theoretically possible but practically unworkable, or workable but not insufficiently useful to be worthwhile?&lt;/p&gt;&#xA;" OwnerUserId="973" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2019-07-07T16:24:11.017" Title="Could a plane be constructed to be fly in fixed-stick roll-stable circles?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12516" PostTypeId="2" ParentId="12515" CreationDate="2015-02-08T01:20:57.440" Score="2" Body="&lt;p&gt;There can't be any such mechanism &lt;em&gt;that works purely by aerodynamic means&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this is that, at least on a short timescale, the air doesn't know which way is up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airflow can feel deviations in pitch and yaw, because they result in the air coming at the aircraft from a different direction (relative to its structure). This gives an opportunity for the shape of the aircraft to be designed such that the altered airflow produces a righting moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you imagine a deviation in pure roll, the air will still be coming at the aircraft from the same direction as before, namely from straight ahead. All of the air flows will be the same as in level flight, just with everything turned to match the roll angle of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There &lt;em&gt;is&lt;/em&gt; the difference that if the wings are not level, the direction of lift is no longer opposite to the direction of gravity. In the not-completely-short timescale, this will cause the aircraft to accelerate with respect to the air. Eventually that will lead to flying at through the air at an angle (that is, changing the angle of attack and/or sideslip), which the aerodynamics &lt;em&gt;can&lt;/em&gt; react to. I think this must be what Peter Kämpf meant when he said that there &lt;em&gt;can&lt;/em&gt; be an &quot;inertial mechanism&quot; for roll stability.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-02-08T01:20:57.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12517" PostTypeId="2" ParentId="12503" CreationDate="2015-02-08T01:29:02.333" Score="5" Body="&lt;p&gt;Ideally runways do not intersect each other, and are all 4300 feet apart (laterally) to allow for simultaneous parallel instrument approaches. &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3d/FAA_diagram_DEN.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Denver&lt;/a&gt; is one such airport that meets all of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sCW4Q.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sCW4Q.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://www.flydenver.com/sites/default/files/environmental/runway.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;flydenver.com&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1520" LastEditorUserId="14897" LastEditDate="2018-05-17T15:59:13.500" LastActivityDate="2018-05-17T15:59:13.500" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="12518" PostTypeId="1" AcceptedAnswerId="12538" CreationDate="2015-02-08T02:21:32.327" Score="11" ViewCount="6430" Body="&lt;p&gt;What is typically the limiting factor for how large a crosswind component a given plane can be safely landed in?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My impression is that larger planes are less sensitive to crosswind than smaller ones -- for example, many commercial airports seem to be doing quite well with a single or multiple parallel runways for transport-category aircraft, whereas airports catering to light aircraft will be proportionally more likely to have (and routinely use) a system of intersecting runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can imagine one reason for this, namely that a plane with a higher landing speed will need less of a crab angle for a given crosswind component. But is this actually the determining factor?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If yes, then is is safe/legal/practical to land a light aircraft in more crosswind than it can usually handle, by landing faster, assuming there's a nice long runway available to decelerate on? (In other words, can an airport make up for having no crosswind runway by having a longer primary runway instead?).&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-02-08T12:56:10.330" LastActivityDate="2015-02-08T22:45:47.770" Title="What determines crosswind limits?" Tags="&lt;landing&gt;&lt;aircraft-limitations&gt;&lt;crosswind&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12519" PostTypeId="1" AcceptedAnswerId="12548" CreationDate="2015-02-08T04:21:14.473" Score="12" ViewCount="4383" Body="&lt;p&gt;How would modern jet fighters engage and defeat prop driven fighters?  Assuming all things being equal (avionics, weapons, etc), if the two aircraft were co-altitude in a level merge, what tactics would the jet use to quickly overwhelm his adversary? &lt;/p&gt;&#xA;" OwnerUserId="7232" LastEditorUserId="3386" LastEditDate="2018-01-02T07:20:41.940" LastActivityDate="2018-11-10T07:32:05.093" Title="How would modern jet fighters engage and defeat prop driven fighters?" Tags="&lt;fighter&gt;&lt;dogfighting&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12520" PostTypeId="2" ParentId="12519" CreationDate="2015-02-08T05:32:21.880" Score="16" Body="&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; This answer is from the original version of the question, which specified a P-51 and an F-22.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What chance would a P-51 have against an F-22?  None whatsoever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 pilot would spot the P-51 on radar as soon as it came over the horizon, pop off an &lt;a href=&quot;https://en.wikipedia.org/wiki/AIM-120_AMRAAM&quot;&gt;AIM-120D&lt;/a&gt; or similar missile at a range of 100 miles, and depart, without the P-51 ever coming within engagement range.  The P-51 pilot would probably never even be aware of the presence of the F-22.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="1677" LastEditDate="2015-02-09T05:52:09.090" LastActivityDate="2015-02-09T05:52:09.090" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12521" PostTypeId="2" ParentId="12515" CreationDate="2015-02-08T07:02:45.460" Score="3" Body="&lt;p&gt;This is not an answer to your question and I am guessing there are some terminology issues here (for example, what does 'aerodynamically recover' mean) but&#xA;it is &lt;strong&gt;certainly&lt;/strong&gt; possible for some aircraft in some configurations to have stable roll dynamics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different aircraft have different dynamics, so partly the answer is it depends.&#xA;Furthermore, the dynamics depend on the operating configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft lateral dynamics have some roll-yaw coupling but it is typically very slow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small perturbations in calm conditions the dynamics can be stable (as in the linearisation eigenvalues have negative real parts) but this can be illusory as the basin of attraction can be very small. This means that typical disturbances can pop you into an 'unstable regime' (I am using the term loosely here).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lateral behaviour of the aircraft around an operating point can be typically characterised by three modes. One mode is what governs the aircraft's primary response and is typically stable and behaves reasonably. Another mode is called the spiral mode; it &lt;strong&gt;is&lt;/strong&gt; possible that this is unstable, and in either case is typically very slow. (Model aircraft typically have a large dihedral to stabilise this mode.) The final eigenvector is a Dutch roll mode  which is&#xA;stable, but is slow and very lightly damped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a further illustration, an aircraft in stable flight can (typically, in reasonable conditions, etc, etc.) be piloted by elevator &amp;amp; rudder alone (the&#xA;linearised dynamics are completely controllable from the elevator &amp;amp; rudder deflection inputs). This would not be possible if these inputs had no effect on roll (because there would be no way to deal with unstable rolling).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bad analogy, consider riding your bicycle without hands. Typically it can be done, but it doesn't take much (bump on road, sneeze,...) to destabilise.&lt;/p&gt;&#xA;" OwnerUserId="3212" LastEditorUserId="3212" LastEditDate="2015-02-08T07:27:00.037" LastActivityDate="2015-02-08T07:27:00.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12522" PostTypeId="1" CreationDate="2015-02-08T10:09:38.920" Score="11" ViewCount="2940" Body="&lt;p&gt;What is required for someone who has CPL, IR and CFI licenses from Iran to fly in USA? What is the requirement to convert license?&lt;/p&gt;&#xA;" OwnerUserId="7233" LastEditorUserId="19" LastEditDate="2017-09-22T06:56:28.817" LastActivityDate="2018-01-20T08:37:48.243" Title="What are the requirements to convert a license from Iran to USA?" Tags="&lt;faa-regulations&gt;&lt;cpl&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12523" PostTypeId="2" ParentId="12522" CreationDate="2015-02-08T11:02:37.953" Score="12" Body="&lt;p&gt;You cannot convert the CPL to FAA-CPL. What is possible is to obtain a FAA-PPL certificate by &lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/foreign_license_verification/&quot; rel=&quot;nofollow noreferrer&quot;&gt;verification&lt;/a&gt; of the your current foreign license. This certificate will be valid as long as your foreign license is (plus medical conditions, and 24-months PPL flight review required for any PPL in the US).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the PPL certificate, you will be able to obtain IR and CPL:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pass IR and CPL written tests.&lt;/li&gt;&#xA;&lt;li&gt;Attend training for IR and CPL practical checks.&lt;/li&gt;&#xA;&lt;li&gt;Accumulate at least 250 flight hours. Time in the foreign country with the foreign license will count as well, but at least 3 hours are required with the FAA instructor. The instructor will vouch for the candidate is ready for the check-ride.&lt;/li&gt;&#xA;&lt;li&gt;Pass CPL and IR practical checks.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A valid residence permit will be necessary to use the FAA-CPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CFI roadmap is similar, written tests and checkrides are mandatory, there no minimum hours to be flown in the US. As a large part of the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1185&quot; rel=&quot;nofollow noreferrer&quot;&gt;knowledge required&lt;/a&gt; is similar to many ICAO-member countries (teaching, meteorology, navigation, aerodynamics, etc) this shouldn't be a problem to be certified FAA CFI.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Related:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8539/do-i-need-a-ppl-license-for-a-cpl-license&quot;&gt;Do I need a PPL license for a CPL license?&lt;/a&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/183/i-have-a-european-easa-license-what-do-i-need-to-do-to-be-allowed-to-fly-in-th?rq=1&quot;&gt;I have a European EASA license - what do I need to do to be allowed to fly in the US?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11521/can-a-pilot-with-an-icao-multi-crew-pilot-license-fly-an-airliner-into-the-u-s?lq=1&quot;&gt;Can a pilot with an ICAO Multi-Crew Pilot License fly an airliner into the U.S.?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;References:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Required knowledge &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#sp14.2.61.f&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 61.123&lt;/a&gt; et seqq.&lt;/li&gt;&#xA;&lt;li&gt;Required flight experience &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1129&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 61.129&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_certification_in_the_United_States&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot certification&lt;/a&gt; in the US on Wikipedia.  &lt;/li&gt;&#xA;&lt;li&gt;Process for foreign CPL to FAA-PPL conversion (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_175&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 61.75&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Flight Instructors &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#sp14.2.61.h&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 62.181&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-02-08T18:39:21.433" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12524" PostTypeId="2" ParentId="12458" CreationDate="2015-02-08T11:15:13.547" Score="11" Body="&lt;p&gt;Looking at the diagram of fatalities, it's immediately obvious that the majority of people are in the safest spot. The most spaced out people are in the deadliest spot. This seems rational to me.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;From a business perspective (and ignoring any ethical considerations&#xA;  of whether passengers should pay more for a better chance of&#xA;  survival), it would seem to me to make more sense to put your highest&#xA;  paying and likely most regular passengers in the safest part of the&#xA;  plane, the rear.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From a business perspective, it makes sense to keep your number of reported casualties as low as possible. Also from an ethical perspective, too, obviously.&lt;/p&gt;&#xA;" OwnerUserId="7235" LastEditorUserId="19" LastEditDate="2015-02-08T11:21:17.307" LastActivityDate="2015-02-08T11:21:17.307" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12525" PostTypeId="2" ParentId="8866" CreationDate="2015-02-08T12:08:52.350" Score="2" Body="&lt;p&gt;Not sure if those are excluded by the &quot;Excluding various first-class seating arrangements&quot; part of your question, but there are a few slightly more original layouts that have been used (or are still used) by some airlines, mostly for business class:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;the &lt;a href=&quot;https://en.wikipedia.org/wiki/Herringbone_seating&quot; rel=&quot;nofollow&quot;&gt;herringbone pattern&lt;/a&gt;. Seats are arranged at about 45° from the axis, and all seats get direct access to the aisle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;reversed seating, as for instance in British Airways' Club World (business class): in a given row, alternating rear- and forward-facing seats. This saves a bit of space laterally (you need more space at the elbow level than for the legs, so by having one person's elbows be at the level of another's legs, you can have more seats in the same width).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3313" LastActivityDate="2015-02-08T12:08:52.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12526" PostTypeId="2" ParentId="12515" CreationDate="2015-02-08T12:24:35.790" Score="6" Body="&lt;p&gt;This will become another of my long posts; after all, lateral stability is more complex than longitudinal stability and involves many more factors. Short answer: It is possible, but not by aerodynamic means, and would incur a drag penalty.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Starting condition&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Assume we have an aircraft with fixed controls, trimmed for straight flight, and make it a glider to remove propulsion effects. Next, let it fly through an asymmetric gust which lifts one wing. For what follows we assume calm air again.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Initial sideslip&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For an outside, earth-fixed observer, a component of lift is pointing sideways and not compensated by weight, so the aircraft will accelerate to that side. From the point of view of the aircraft, lift is still acting in the plane of symmetry, but gravity does not and will cause it to sideslip. This will mainly evoke these reactions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Directional stability &lt;span class=&quot;math-container&quot;&gt;$c_{n\beta}$&lt;/span&gt;: The aircraft will yaw into the wind because the vertical tail will create a side force (&quot;weathervane effect&quot;).&lt;/li&gt;&#xA;&lt;li&gt;Dihedral effect &lt;span class=&quot;math-container&quot;&gt;$c_{l\beta}$&lt;/span&gt;: The additional lift on the windward wing will lift this wing. Also, the additional side force on the vertical tail, which yaws the aircraft, will cause a supporting rolling moment. Roll damping (&lt;span class=&quot;math-container&quot;&gt;$c_{lp}$&lt;/span&gt;) will limit the amount by which the aircraft rights itself up, however.&lt;/li&gt;&#xA;&lt;li&gt;Yaw moment due to dihedral and wing sweep: The lift difference due to dihedral and wing sweep will retard the upwind wing, causing a yawing motion into the wind. This effect can be added to the directional stability &lt;span class=&quot;math-container&quot;&gt;$c_{n\beta}$&lt;/span&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Eventual (almost) coordinated turn&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The aircraft will start to fly a coordinated turn, because all forces try to drive sideslip to almost zero, and on their way to do so start a yawing motion. In contrast to that, the roll angle will not change further once sideslip stops, because the sideslip-induced rolling moments stop as well. However, if a roll angle remains, the aircraft will now begin to turn. This opens up a new bunch of effects, because  now we have asymmetric flow: Due to the yawing motion, airspeed varies over wingspan and sideslip angle varies over length:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rolling moment due to yawing motion &lt;span class=&quot;math-container&quot;&gt;$c_{lr}$&lt;/span&gt;: The outer wing (which was the leeward wing during sideslip before) now travels faster, creating more lift. This causes a rolling moment which increases roll angle.&lt;/li&gt;&#xA;&lt;li&gt;Since the angle of attack would be the same in a coordinated turn over the whole wingspan, drag will behave proportional to lift and increase with the local turn radius. This drag difference will create a small yawing moment which will let the inner wing advance, until the dihedral effect will kick in and create enough of a difference in angle of attack that the drag on the inner and on the outer wing are equal again. Since induced drag is proportional to the square of the lift coefficient, the wing will still create less lift on the inner wing than on the outer wing, but the difference will be reduced. If the airplane climbs or descends during the turn, angle of attack will vary over span and will create an uprighting moment on the descending airplane (and vice versa).&lt;/li&gt;&#xA;&lt;li&gt;Yawing moment due to yawing motion &lt;span class=&quot;math-container&quot;&gt;$c_{nr}$&lt;/span&gt;: This is also called yaw damping and creates a yawing moment opposed to the yawing motion. Contributing factors are the vertical tail which sees a sideward flow component due to the yawing motion, and the drag distribution along the wingspan. Aircraft with a long tail have high yaw damping and, in combination with plenty of dihedral, tend to be more roll stable than short-tailed aircraft. Here the long tail forces the wing into a sideslip which uprights the aircraft. This configuration is found on free-flying models which do indeed upright themselves from shallow banks.&lt;/li&gt;&#xA;&lt;li&gt;Centrifugal forces: The sideward component of lift is now balanced by the centrifugal force due to the turn. However, the centrifugal forces also will create an uprighting rolling moment which depends on the spanwise distribution of masses.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GMKAX.png&quot; alt=&quot;centrifugal forces on banking and turning aircraft&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the outer wing has a bigger turn radius &lt;span class=&quot;math-container&quot;&gt;$R$&lt;/span&gt;, but the same angular velocity &lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; as the rest of the airplane. This causes it to experience more centrifugal force &lt;span class=&quot;math-container&quot;&gt;$m\cdot \omega^2\cdot R$&lt;/span&gt; than the inner wing (symbolized by the length of the parallel arrows). I used a rather steep attitude to get the point across, but the same holds true at shallower bank angles. This is the uprighting inertial moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the relative size of these effects, the aircraft will either right itself up, stay at this roll angle or dive ever deeper into the turn. Agile aircraft with low roll inertia will have too little uprighting moment and are likely to spiral dive. More stable configurations with big vertical tails and ample of dihedral will either continue to turn gently or right themselves up.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Effects at non-zero roll rates&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now this was all done under the assumption that the roll angle changes very slowly. A too small vertical tail and/or too much dihedral will excite the Dutch roll motion, and now the roll angle oscillates, adding more roll-induced effects. To keep this answer reasonably short, I will not list them here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_880&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sweptback configurations optimized for fast flight&lt;/a&gt; (= with small vertical tails close to the wing) are typical examples where the ratio &lt;span class=&quot;math-container&quot;&gt;$\dfrac{c_{l\beta}}{c_{n\beta}}$&lt;/span&gt; is too high and the Dutch roll eigenmode has too little damping. Free flying model aircraft, on the other hand, cannot afford to fall into a spiral dive, and by giving them big vertical tails and long lever arms, which allows them to have substantial dihedral, and a high radius of roll inertia, they can be made to upright themselves.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-06-18T21:49:10.730" LastActivityDate="2019-06-18T21:49:10.730" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="12528" PostTypeId="1" AcceptedAnswerId="12530" CreationDate="2015-02-08T14:13:04.810" Score="36" ViewCount="15936" Body="&lt;p&gt;For commercial jets, the engines are complex parts of the aircraft, are the most expensive components, and must be carefully maintained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3KSmY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3KSmY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.csiaviation.com/private-jet-charter-company-services.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a company buys an aircraft, do they also own the engines, or are they still the property of the engine manufacturer? What happens when an engine must be exchanged?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-10-09T20:15:13.380" LastActivityDate="2018-11-16T17:22:34.860" Title="Jet engines: are they owned by the airline or just rented?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12529" PostTypeId="1" AcceptedAnswerId="12546" CreationDate="2015-02-08T14:29:09.427" Score="10" ViewCount="1215" Body="&lt;p&gt;It was not uncommon in the 60s and 70s to have B747 ferrying a spare engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pFapI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://australianaviation.com.au/2011/07/qantas-744-ferries-spare-engine-to-johannesburg/&quot; rel=&quot;noreferrer&quot;&gt;Australian Aviation&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was that allowed only on aircraft specifically designed with a pod, or was that possible to add the equipment on any B747. What is the regulation applicable? (in the US for instance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional question: is this still commonly used today in civil aviation?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="65" LastEditDate="2015-02-08T15:51:30.147" LastActivityDate="2015-02-08T23:59:23.177" Title="What are the requirements of ferrying a spare engine?" Tags="&lt;engine&gt;&lt;ferry-flight&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12530" PostTypeId="2" ParentId="12528" CreationDate="2015-02-08T15:15:00.460" Score="54" Body="&lt;p&gt;These days, engine manufacturers are not any more in the business of selling engines, but &lt;a href=&quot;http://www.economist.com/node/12887368&quot; rel=&quot;noreferrer&quot;&gt;selling thrust&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls-Royce were the first to offer this, and today most Rolls-Royce engines send telemetry data to four centers, the biggest one in Derby, in Great Britain, where every engine is under surveillance. An inspection can be scheduled at or spare parts can be directed to the right destination even before the pilots or the airline know that one of their engines has a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By now, 80% of Rolls-Royce engines are sold at a loss which is recouped by a hourly fee paid under the &lt;a href=&quot;http://www.som.cranfield.ac.uk/som/dinamic-content/media/Executive%20Briefing%206%20-%20RR%20Totalcare%20-%20Mtg%20the%20Needs%20of%20Key%20Customers%20%20-%208%20Mar%2010%20v9.pdf&quot; rel=&quot;noreferrer&quot;&gt;TotalCare (.pdf!)&lt;/a&gt; program, and that center in Derby is monitoring maybe 4000 of them at the same time. Rolls-Royce has accumulated a treasure of engine operations data, which enables it to consult airlines on best practices. This makes it very hard for a third party to steal maintenance business from Rolls-Royce. All maintenance cost is covered by the TotalCare fee which now accounts for more than half of Rolls-Royce's revenue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.geaviation.com&quot; rel=&quot;noreferrer&quot;&gt;GE&lt;/a&gt; and &lt;a href=&quot;http://www.pw.utc.com/Home&quot; rel=&quot;noreferrer&quot;&gt;Pratt&amp;amp;Whitney&lt;/a&gt; have &lt;a href=&quot;http://www.pwc.ca/en/service-support/general-aviation-pay-by-the-hour&quot; rel=&quot;noreferrer&quot;&gt;similar programs&lt;/a&gt;. In GE's case, it is called &lt;a href=&quot;http://www.innovationexcellence.com/blog/2012/11/04/open-services-innovation/&quot; rel=&quot;noreferrer&quot;&gt;OnPoint&lt;/a&gt;, sold as &quot;Power by the Hour&quot;. The airline does not pay for the engines, but for the time they are flying. Now the engine manufacturer has a strong incentive to improve the reliability of its engines, but also a strong lever to push out third-party maintenance providers.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-08T20:50:00.873" LastActivityDate="2017-10-08T20:50:00.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12531" PostTypeId="1" CreationDate="2015-02-08T17:32:22.983" Score="0" ViewCount="256" Body="&lt;p&gt;While on a flight to San Francisco from New York, somewhere over California or Nevada, I saw this from my window; what the heck is it? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/erSB9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3869" LastActivityDate="2015-02-08T17:43:10.030" Title="Strange facility out west near California; what is this place?" Tags="&lt;general-aviation&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ClosedDate="2015-02-08T18:07:48.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="12532" PostTypeId="1" CreationDate="2015-02-08T17:34:25.130" Score="2" ViewCount="983" Body="&lt;p&gt;A few years ago, my brother and I were aboard an Emirates flight from Australia to New Zealand. At the time, I was 16 and he was 14. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At one point in the flight we were both offered alcoholic drinks. Considering the drinking age where I am from is 18, and ID is required if you look under 25, this came as quite a surprise to the both of us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering different countries have different laws and aircraft often have multinational crew and passengers, what laws govern international flights?&lt;/p&gt;&#xA;" OwnerUserId="3878" LastActivityDate="2015-02-08T18:37:30.247" Title="Is there a set of laws which govern international flights?" Tags="&lt;airline-operations&gt;&lt;international&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-02-09T11:38:39.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="12533" PostTypeId="2" ParentId="12531" CreationDate="2015-02-08T17:43:10.030" Score="5" Body="&lt;p&gt;In case anyone's wondering, it's the &lt;a href=&quot;http://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project&quot; rel=&quot;nofollow noreferrer&quot;&gt;Crescent Dunes Solar Energy Project&lt;/a&gt;, credit to &lt;a href=&quot;https://scifi.stackexchange.com/questions/81211/strange-facility-out-west-near-california-what-is-this-place&quot;&gt;Trish Ling&lt;/a&gt; at Sci-Fi.&lt;/p&gt;&#xA;" OwnerUserId="3869" LastEditorUserId="-1" LastEditDate="2017-04-13T12:43:39.120" LastActivityDate="2015-02-08T17:43:10.030" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12534" PostTypeId="2" ParentId="12532" CreationDate="2015-02-08T18:16:27.807" Score="0" Body="&lt;p&gt;International Airline is bound to follow the law of country of registration. Hence your flight limits you to &lt;a href=&quot;https://www.gov.uk/foreign-travel-advice/united-arab-emirates/local-laws-and-customs&quot; rel=&quot;nofollow noreferrer&quot;&gt;dringking law&lt;/a&gt; in Abu Dhabi which is 18&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note some airline, Turkish &lt;a href=&quot;http://www.turkishairlines.com/en-int/corporate/press-room/press-releases/press-release-detail/public-announcement-alcohol-service-in-aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, have some policy not to serve alcohol on certain flights. On my experience with Hong Kong airline, the flight in-bound to Hong Kong only serve juices where out-bound had Tsing Tao :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A not a really related topic but something more to read on travel.SE : &lt;a href=&quot;https://travel.stackexchange.com/questions/30223/is-it-legal-to-drink-your-own-alcohol-onboard-a-plane-over-international-waters&quot;&gt;Is it legal to drink your own alcohol onboard a plane over international waters?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2015-02-08T18:37:30.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12536" PostTypeId="2" ParentId="12279" CreationDate="2015-02-08T19:26:59.283" Score="2" Body="&lt;p&gt;This is speculation, but in the absence of an obvious technical reason it's at least possible that this is because category C/D pilots have better lobbyists than category A/B ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found an interesting but somewhat dated (1995) &lt;a href=&quot;http://www.terps.com/ifrr/jun95.pdf&quot; rel=&quot;nofollow&quot;&gt;document &lt;/a&gt; called &lt;em&gt;Establishing Visibility Minimums&lt;/em&gt;; the author used to chair the &lt;a href=&quot;http://www.alpa.org/&quot; rel=&quot;nofollow&quot;&gt;ALPA&lt;/a&gt; TERPS committee. It says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[The TERPS concepts] are a combination of science and politics, with a&#xA;  lot of undocumented historical precedence thrown in for good measure&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The political horse-trading that led to the 1976 [TERPS] revision [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, we shouldn't necessarily assume that rules and regulations are entirely based on well-defined and documented technical criteria.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The (now outdated) 1976 chart in that document shows a default minimum of 1 mile visibility for all categories (with the single exception of an ILS with DH of 200', which is 3/4) or 1/2 with approach lighting, so a 7/8 minimum is a more recent change. So you could ask, why was this change made? One way would be to find the &lt;a href=&quot;http://en.wikipedia.org/wiki/Notice_of_proposed_rulemaking&quot; rel=&quot;nofollow&quot;&gt;NPRM&lt;/a&gt; or other public records that detail the reasons for the change, but in practice it may be easier to contact the FAA directly and ask them (possibly under the &lt;a href=&quot;http://en.wikipedia.org/wiki/Freedom_of_Information_Act_%28United_States%29&quot; rel=&quot;nofollow&quot;&gt;FOIA&lt;/a&gt; if the information isn't already public).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One theoretical possibility is that the airline industry successfully lobbied to have 'their' minimums reduced in certain circumstances due to better training, equipment or whatever, and this approach is one of the affected ones. Diverting airline flights is enormously expensive, and the industry has a large incentive to make sure that as many instrument approaches succeed as possible. If lowering the minimums by 1/8 allows even a few flights a day to start an approach that would otherwise be illegal, that could add up to a huge financial saving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this is entirely guesswork on my part, I just wanted to make the point that sometimes we look for a technical explanation where the real reason is financial or political. For a definite answer, I would ask the FAA directly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-08T19:26:59.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12537" PostTypeId="2" ParentId="12367" CreationDate="2015-02-08T19:45:52.047" Score="4" Body="&lt;p&gt;ICAO Annex 11 &quot;Air Traffic Services&quot; is probably the top document. Implementations in national law might vary.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-02-08T19:45:52.047" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12538" PostTypeId="2" ParentId="12518" CreationDate="2015-02-08T20:00:58.913" Score="10" Body="&lt;p&gt;Your question is not easily answered, at least in my opinion, but I'll have a go at it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your impression that larger airplanes are less sensitive to xwinds than smaller airplanes is correct, very much so in my experience. I lack the expertise to give you the aerodynamic basis, the equations if you will, but I'm fairly certain that saying an aircraft's sensitivity to a xwind is inversely proportional to it's mass, landing speed, and wing loading is a correct statement. As I remember, the max demonstrated xwind for a Cessna 172 is 15 kts, for a 747 either 25 or 30 kts, and I would much rather be landing a 747 in a 30 kt xwind than a 172 in a 15 kt xwind. In 747 sims we would occasionally crank the xwind up to 40 kts for an interesting but still safe landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using extra speed in a small aircraft to help is not, in my opinion, a good idea. You'd certainly want to add a bit to your approach speed to handle gusting conditions (which typically accompany crosswinds), but what you need to do is transition from flying speed to non-flying speed as quickly as possible rather than extending the time of that transition. You need to get the weight off the wings and on to the wheels as quickly as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one exception to what I just said. Back in the 1950s when I first learned to fly, they used to teach what they called 'wheel landings' for handling crosswinds in taildraggers. The problem with a taildragger is that the c.g. is behind the main gear. If you touch down in any kind of a crab, it wants to switch ends. In other words, a ground-loop. The idea of a 'wheel landing' was to get the main wheels on the runway with extra speed (after having slipped to the touchdown) so that the rudder (with the tail still off the ground) had plenty of authority to counteract weathervaning, and of course with the upwind aileron fully up. Then you were supposed to keep the airplane straight while the your speed dissipated to where the tail could no longer fly. I have no idea if they still teach that technique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now you're the PIC and having to decide whether to land in a xwind. Following are some of the things I can think of that might enter into your decision making:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What's your personal confidence level? If you're nervous about the situation you're probably not going to do as good a job as if you were relaxed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What's your experience level in the airplane? Aircraft, even of the same weight class, vary in their handling qualities in a xwind, and the more you've flown them in xwinds, the better you're going to be in that model of aircraft in a xwind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;High wing or low wing? The closer to the ground you get the more the wind decreases, and that few feet of difference can make a difference. Also, I suspect, but do not know, that having most of the wing below the c.g. rather than above the c.g. helps.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the runway surface, and what is its condition? In other words, how slippery is it going to be. A dry paved runway is, of course, the best. However, a dry paved runway with a lot of reverted rubber in 120 F (49 C) temperatures can be interesting. Ice or wet grass is perhaps the worst. I put a Cessna 150 off the runway in wet grass back in the 1970s.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How bad do you need to land there? Some might say that doubts about being able to safely land should always override the need to land, but that's not the real world.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For a light aircraft, you may be able to turn that strong xwind into a strong headwind by using a taxiway. I've done that at a uncontrolled field.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A word of caution: Just because the xwind is within the max demonstrated xwind component does not necessarily mean you can safely land, it just means an experienced test pilot did it on a reasonable runway surface. The max demonstrated xwind is a guideline that is sometimes safe to exceed, sometimes not, and sometimes not safe to even get close to.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-02-08T22:45:47.770" LastActivityDate="2015-02-08T22:45:47.770" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12539" PostTypeId="2" ParentId="2854" CreationDate="2015-02-08T20:39:00.480" Score="4" Body="&lt;p&gt;Having spent 3 days with one of the investigators of the Swiss Air 111 flight during an international safety seminar, he said the dump was unnecessary as that bird was certified to land at its current weight when an emergency was declared. That very basic mistake cost all lives, as had he flown direct to land, he would have been on the ground before the fire was big enough to impact the cockpit. Both pilots had donned O2 masks. The fire burned through the copilots oxygen hose and turned it into a blow torch to the side of his head before they hit the water. This bird hit the water at an angle and speed which caused extreme water pressure to be forced into the fuselage. Pressures were so great, the water entered passengers bodies orifices and many had the top of their heads explode. He said it was a gruesome job for the recovery workers.&lt;/p&gt;&#xA;" OwnerUserId="7246" LastEditorUserId="19" LastEditDate="2015-02-08T20:42:15.617" LastActivityDate="2015-02-08T20:42:15.617" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12540" PostTypeId="2" ParentId="12518" CreationDate="2015-02-08T22:09:04.320" Score="0" Body="&lt;p&gt;For Part 23 airplanes, the answer is:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol1/xml/CFR-2011-title14-vol1-sec23-233.xml&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR §23.233&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Directional stability and control.&lt;/p&gt;&#xA;&lt;p&gt;(a) A 90 degree cross-component of wind velocity, demonstrated to be safe for taxiing, takeoff, and landing must be established and must be not less than 0.2 VSO.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-08T22:34:04.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12541" PostTypeId="1" AcceptedAnswerId="12544" CreationDate="2015-02-08T22:27:04.683" Score="50" ViewCount="9680" Body="&lt;p&gt;If the flight distance permits, the B737-800 will cruise at FL350, the A320 a little bit higher... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DvO6L.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DvO6L.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Flying at FL370. &lt;a href=&quot;https://www.facebook.com/golfcharlie232/photos/a.366916336733937/1589239047834987/?type=3&amp;amp;theater&quot; rel=&quot;nofollow noreferrer&quot;&gt;Photo&lt;/a&gt;: Live from the Flight Deck by &lt;a href=&quot;https://fr-fr.facebook.com/pg/golfcharlie232/videos/&quot; rel=&quot;nofollow noreferrer&quot;&gt;GolfCharlie232&lt;/a&gt; (reframed)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elements such as time to reach cruise altitude, engine and airframe efficiency at this altitude, and acceptable cabin pressure surely influence the choice, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are exactly the important criteria used, and the compromises made by engineers?&lt;/li&gt;&#xA;&lt;li&gt;Would engineers choose other altitudes if the technology or any other current limits could be improved?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-06-06T16:57:32.727" LastActivityDate="2020-06-06T16:57:32.727" Title="Why are many jet aircraft designed to cruise around FL350-370?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;cruise&gt;&lt;flight-level&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="12542" PostTypeId="2" ParentId="12541" CreationDate="2015-02-08T22:47:12.017" Score="5" Body="&lt;p&gt;As mentioned in the comment above, I'm not sure where you are getting the FL400 reference from but here are a few common reasons for flying higher (not necessarily FL400):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuel savings (more efficient flying at higher altitudes -- see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;Link&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Higher true airspeed&lt;/li&gt;&#xA;&lt;li&gt;Get above any weather/turbulence/icing&lt;/li&gt;&#xA;&lt;li&gt;Better NAVAID/comm reception&lt;/li&gt;&#xA;&lt;li&gt;Better visibility&lt;/li&gt;&#xA;&lt;li&gt;More altitude for better gliding distance (yes, not a huge deal for airliners, but think SE)&lt;/li&gt;&#xA;&lt;li&gt;Less traffic&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some disadvantages could include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;More susceptible to compressor stalls&lt;/li&gt;&#xA;&lt;li&gt;More altitude to lose if loss of cabin pressure/rapid decompression&lt;/li&gt;&#xA;&lt;li&gt;Worse weather to include icing&lt;/li&gt;&#xA;&lt;li&gt;Need to be RVSM-equipped (if flying up to FL410).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerDisplayName="user3309" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-02-09T02:03:29.790" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="12543" PostTypeId="2" ParentId="12519" CreationDate="2015-02-08T22:56:07.727" Score="5" Body="&lt;p&gt;Mark's answer covers what would happen in a real world scenario.&lt;/p&gt;&#xA;&lt;p&gt;However, assuming that they've somehow accidentally got into range of each other... the F-22 pilot wasn't paying attention etc. And also assuming somehow that they have the same weapons and avionics, then one of the following would probably happen&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Both aircraft have the weapons/avionics of the P-51&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The F-22 climbs. It has a climb rate HUGELY in excess of the P-51. Once above the P-51, it can &amp;quot;Boom and Zoom&amp;quot; against the P-51 all day. Dive in behind, open fire, climb away again... without ever being in a tiny amount of danger. By the time the P-51 turns to point its guns at where the F-22 was, the F-22 has rocketed away (like literally, by comparison, rocketed). The F-22 simply repeats this until the P-51 is dead.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;strong&gt;Both aircraft have the weapons/avionics of the F-22&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Assuming a head-on pass, the F-22 detects the P-51 long before the P-51 even knows an F-22 is nearby. The F-22 blows the P-51 out of the sky.&lt;/p&gt;&#xA;&lt;p&gt;Assuming the F-22 misses and they pass each other, are at a comparable speed, and assuming that from now on either can get a lock on the other with equal chance, the F-22 simply uses its vastly superior maneuverability to turn in behind the P-51, fires another missile and casually leaves after again blowing the P-51 up.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The aircraft are in entirely different leagues.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-09T06:17:33.483" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12544" PostTypeId="2" ParentId="12541" CreationDate="2015-02-08T23:07:44.737" Score="34" Body="&lt;p&gt;There are multiple factors that affect an aircraft based on its cruise altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cruise altitude directly affects the aircraft pressurization and aerodynamics. In order to keep the cabin altitude around 6000 to 8000 feet, the fuselage would have to withstand a higher pressure differential. This would require more material, and make the plane heavier. Newer materials used on the 787 and A350 handle these loads better, which allows a higher pressure differential and larger windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude also affects the aerodynamics. Aircraft typically cruise at a certain Mach number at high altitudes. The indicated airspeed for a certain Mach number gets lower with higher altitude. This can result in lower drag, but poses challenges as the airspeed drops lower. See: &lt;a href=&quot;https://aviation.stackexchange.com/q/9188/1696&quot;&gt;What determines the maximum altitude a plane can reach?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see &lt;a href=&quot;https://aviation.stackexchange.com/a/12569/1696&quot;&gt;the answer by Peter Kämpf&lt;/a&gt; for more detail about the aerodynamic aspects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher altitudes, less air is available for the engines, reducing the available power. Along with this there are efficiency benefits. See: &lt;a href=&quot;https://aviation.stackexchange.com/q/1609/1696&quot;&gt;Why do jet engines get better fuel efficiency at high altitudes?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/12555/1696&quot;&gt;the answer by Ghillie Dhu&lt;/a&gt; explains, those benefits stop increasing around FL360.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lack of breathable oxygen and increased pressure forces on the fuselage caused by the lower air pressure also lead to greater risks, resulting in tighter regulations on aircraft intending to fly higher. These regulations will add additional cost to flying higher, affecting decisions on service ceilings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol1/xml/CFR-2011-title14-vol1-sec25-365.xml&quot; rel=&quot;noreferrer&quot;&gt;§ 25.365&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) The airplane structure must be designed to be able to withstand the pressure differential loads corresponding to the maximum relief valve setting multiplied by a factor of 1.33 for airplanes to be approved for operation to 45,000 feet or by a factor of 1.67 for airplanes to be approved for operation above 45,000 feet, omitting other loads.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So for planes operating over 45,000 feet, the structure must be able to withstand an even higher pressure load factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol1/xml/CFR-2011-title14-vol1-sec25-1441.xml&quot; rel=&quot;noreferrer&quot;&gt;§ 25.1441&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) The oxygen flow rate and the oxygen equipment for airplanes for which certification for operation above 40,000 feet is requested must be approved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Planes operating over 40,000 feet must get special approval for the oxygen system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2011-title14-vol1/xml/CFR-2011-title14-vol1-sec25-841.xml&quot; rel=&quot;noreferrer&quot;&gt;§ 25.841&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) The airplane must be designed so that occupants will not be exposed to a cabin pressure altitude that exceeds the following after decompression from any failure condition not shown to be extremely improbable:&lt;br&gt;&#xA;  (i) Twenty-five thousand (25,000) feet for more than 2 minutes; or&lt;br&gt;&#xA;  (ii) Forty thousand (40,000) feet for any duration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The cabin altitude is not allowed to exceed 40,000 feet under any condition that isn't extremely improbable. The higher the plane flies, the more difficult this will be to certify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Business jets tend to have higher cruise altitudes, because the smaller structure is easier to reinforce for higher pressures, and typically sees fewer load cycles. Efficiency is also not as important as speed and comfort, so some weight can be spared for the stronger fuselage. The higher altitude also affords more flexibility in routing since most other traffic including commercial airliners are cruising at lower altitudes. Business jets may also be certified under less-stringent regulations.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-02-17T21:30:20.700" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12545" PostTypeId="2" ParentId="12493" CreationDate="2015-02-08T23:28:48.973" Score="4" Body="&lt;p&gt;If there's such a thing as a standard &lt;em&gt;maximum&lt;/em&gt; altitude for sport parachuting, the best answer would be 15,000' MSL, as above this CFR 91.211 requires supplemental oxygen for all passengers - and providing this to sport jumpers would be an expensive nuisance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this does not vary with ground elevation - so indeed jumpers in the Denver area will not be able to get as high above the drop zone (and thus as much freefall time) as those starting from a lower altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that this is a limitation on people - there is no standard maximum for jump aircraft  Some aircraft types (e.g. Cessna 182) would struggle to get anywhere near 15,000' MSL in a reasonable time. Others (e.g. Cessna Caravan) can haul a full load of jumpers to 15,000' MSL rapidly and without breaking a sweat.  The Caravan could carry jumpers to its service ceiling of 25,000' provided they had oxygen and the pilot obtained ATC clearance (required above FL 180 = 18,000').&lt;/p&gt;&#xA;" OwnerUserId="7176" LastActivityDate="2015-02-08T23:28:48.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12546" PostTypeId="2" ParentId="12529" CreationDate="2015-02-08T23:59:23.177" Score="10" Body="&lt;p&gt;It's a manufacturer option on some larger planes - basically adding a bit of structure and some attachment points. And it's expensive enough that airlines think about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today's engines are much, much more reliable than the ones used in the 1960s so the need to move engines around by bolting them on to the next thing going that way is not what it once was. There is also a larger air cargo market, and it's likely cheaper in general to put the replacement on a pallet rather than under a wing.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-02-08T23:59:23.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12548" PostTypeId="2" ParentId="12519" CreationDate="2015-02-09T00:36:13.103" Score="26" Body="&lt;h2&gt;Merge&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Assuming neither aircraft tried for a head-on guns snapshot, the goal of the jet against the prop will be to go out of plane with the prop post merge and deny the prop a quick guns solution.  By far the easiest way for the jet to go out of plane is to extend and then take the fight vertically.  This means that the jet is in full AB coming into the merge and well above cornering speed, while the prop is coming into the merge at its best corning speed hoping to get a quick snapshot.  As the aircraft approach both pilots tighten down and pass as close as possible to prevent either aircraft from taking angles right after the merge (ie, so that neither aircraft has a turning advantage immediately post merge).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Post Merge&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As the aircraft make their first pass, the prop (knowing full well the jet will take the fight vertically) begins a max performance turn hoping to quickly take angles and give itself a quick snapshot against the jet as the jet climbs.  However, the jet, knowing the prop is looking for a radius fight, extends the merge horizontally, at Mach 1+ and then begins a supersonic climb upwards.  Due to the lower thrust to weight ratio of the prop, most of the props potential energy comes in the form of its altitude; however, the jet has liquid potential energy in the form of fuel, and many can accelerate in the vertical, this gives the jet a decided advantage against the prop.  Because the prop cannot climb with the jet, and the jet is now outside of its guns range, the prop must remain at altitude and wait for the jet to attack.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Out of Plane&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The jet, moving vertically, has now successfully moved out of plane with the prop rendering the turning radius of the prop moot.  An unchallenged out of plane maneuver is certain victory for the jet.  The jet can now cut the turning circle of the defender from above.  The best hope for the prop is to either pull hard into the jet trying to force an overshoot (and hope that the jet isn't already anticipating this and drawing a wall of lead between this anticipated spot and his current location) or, to wait until the last minute and pull into the vertical with the jet (causing a vertical merge) and hope for a head-on snapshot.  Either way, the jet can quickly disengage vertically again, causing the prop to bleed precious energy with these high G maneuvers, and then reengage when he has the advantage again.  Each time the jet disengages, the prop is left scrambling to regain its depleted energy, and the jet is maneuvering to prevent the prop from ever being able to fully recover.  This means that as the prop dives to gain speed, the jet dives after it, forcing another high G pull from the prop for another overshoot, or, if the prop tries to extend horizontally, the jet attacks again, forcing the prop to use more energy.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The jet will either force a mistake out of the prop and kill it, or the prop will eventually run out of altitude and airspeed and either auger into the ground, or be killed when he doesn't have the energy to force the overshoot, or climb vertically again.  This, of course, ignores things like thrust vectoring, and the flight computers, in aircraft like the super hornet, which give certain Gen 4/5 aircraft supermaneuverability--meaning, post merge, most Gen 4/5 aircraft could just out rate the prop and the fight would likely be over in seconds.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-02-09T00:43:30.520" LastActivityDate="2015-02-09T00:43:30.520" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12549" PostTypeId="2" ParentId="12493" CreationDate="2015-02-09T00:50:52.437" Score="6" Body="&lt;p&gt;As paul mentioned, &quot;standard&quot; altitudes for sport skydiving facilities near sea level are in the 10,500-13,500 AGL range.  Dropzones significantly above sea level typically either reduce their jump height to stay under 15,000 MSL or provide supplemental oxygen in the plane and go up to 18,000 MSL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many dropzones will offer jumps from 18,000 MSL for an additional fee over the regular jump.  Supplemental oxygen is provided.  Jumps in the 18,000-23,000 MSL range are also possible but rarer because of the increased needed for coordination with ATC.  Above 18,000, the risk of hypoxia increases rapidly.  &lt;a href=&quot;http://youtu.be/tXa4w4aYKEk?t=1m56s&quot;&gt;This video&lt;/a&gt; shows jumpers suffering from severe hypoxia at 21,000'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is at least &lt;a href=&quot;http://www.halojumper.com/&quot;&gt;one facility&lt;/a&gt; in the United States that takes recreational skydivers up to 30,000 MSL.  It requires additional training and wearing oxygen in freefall.  This facility uses a King Air, and I know it has also been done from a PAC750.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2015-02-09T00:50:52.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12550" PostTypeId="1" AcceptedAnswerId="12553" CreationDate="2015-02-09T01:35:11.880" Score="10" ViewCount="5962" Body="&lt;p&gt;In calm wind situations, approaching an uncontrolled airport with no other aircraft reporting on CTAF, which runway should I select that would cause the least safety hazard?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially at an airport with one runway, I don't want to set up to land head-on with an aircraft flying without a radio.&lt;/p&gt;&#xA;" OwnerUserId="7248" LastEditorUserId="167" LastEditDate="2015-02-09T03:29:43.520" LastActivityDate="2017-03-30T19:07:28.220" Title="In calm winds, which runway should I select at an untowered airport?" Tags="&lt;general-aviation&gt;&lt;radio-communications&gt;&lt;runways&gt;&lt;wind&gt;&lt;student-pilot&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12551" PostTypeId="1" AcceptedAnswerId="12552" CreationDate="2015-02-09T01:41:49.333" Score="5" ViewCount="715" Body="&lt;p&gt;I've noticed on windy days that keeping the aircraft coordinated can be difficult -- the ball will tend to bounce back and forth in the turn coordinator, and I will find myself &quot;chasing&quot; it with the rudder pedals.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any advice for managing this situation?  At cruise it doesn't worry me as much as setting up for approach to land. I think I've read too many stall/spin in the pattern stories lately...&lt;/p&gt;&#xA;" OwnerUserId="7248" LastEditorUserId="14897" LastEditDate="2021-05-03T05:06:16.780" LastActivityDate="2021-05-03T05:06:16.780" Title="How do I keep coordinated on a windy day?" Tags="&lt;flight-training&gt;&lt;wind&gt;&lt;student-pilot&gt;&lt;rudder&gt;&lt;coordinated-flight&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12552" PostTypeId="2" ParentId="12551" CreationDate="2015-02-09T01:51:52.453" Score="7" Body="&lt;p&gt;Don't chase the ball.  Heck if you're VFR/VMC, you should barely be glancing at the ball or any of your instruments and should have eyes outside.  Remember flying a little uncoordinated alone is not going to force a spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stall + Yaw = Spin&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do we mitigate this during gusty approaches?  We fly a little bit faster.  I like to use 1/2 the gust factor and add that to my final approach speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not saying accept being uncoordinated, but when it's gusty out you don't chase airspeed, so why chase the ball?&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-09T01:51:52.453" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12553" PostTypeId="2" ParentId="12550" CreationDate="2015-02-09T02:48:37.943" Score="12" Body="&lt;p&gt;Often uncontrolled fields will publish a preferred calm wind runway in the Airport/Facility Directory. When one isn't published the calm wind runway is &lt;em&gt;usually&lt;/em&gt; the longest runway, which gives you a 50/50 chance at guessing right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To further reduce your likelihood of winding up face to face with another arriving aircraft you should self-announce on the CTAF and overfly the field to observe the traffic pattern. Also, turn on all the external lights 5 miles out. If there is traffic in the pattern you should work yourself into the same pattern everyone else is using.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pattern is empty my personal practice is to pick the approach to the longest runway with the fewest obstructions, and ideally one that doesn't overfly residential areas (where it's practical to avoid doing so). &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3504" LastEditDate="2015-02-09T14:28:01.463" LastActivityDate="2015-02-09T14:28:01.463" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12554" PostTypeId="2" ParentId="12550" CreationDate="2015-02-09T02:51:51.893" Score="4" Body="&lt;p&gt;In addition to voretaq7's answer, you could also check the &lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_aerodrome_forecast&quot; rel=&quot;nofollow&quot;&gt;terminal aerodrome forecast (TAF)&lt;/a&gt;/&lt;a href=&quot;http://en.wikipedia.org/wiki/Maximum_elevation_figure&quot; rel=&quot;nofollow&quot;&gt;maximum elevation figure (MEF)&lt;/a&gt; and see what is the weather forecast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's IMC and the airport has only a single ILS, then takeoff from the runway with the ILS (since that's the runway IFR aircraft will be landing on).&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorUserId="65" LastEditDate="2015-02-09T14:56:35.123" LastActivityDate="2015-02-09T14:56:35.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12555" PostTypeId="2" ParentId="12541" CreationDate="2015-02-09T02:52:08.743" Score="48" Body="&lt;p&gt;In a word, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tropopause&quot;&gt;tropopause&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gas turbine engine efficiency improves with colder &amp;amp; denser air. As an airplane climbs through the troposphere, the density &amp;amp; temperature both drop, and the loss of density is more than offset by the lower temperature. Above the tropopause, however, the density continues to drop while the temperature holds (approximately) constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;https://en.wikipedia.org/wiki/U.S._Standard_Atmosphere&quot;&gt;U.S. Standard Atmosphere&lt;/a&gt; model, this occurs at 36,089 feet. This represents a local (possibly global) optimum altitude for efficiency (and if there is a better optimum at a higher altitude, it's inaccessible for other reasons).&lt;/p&gt;&#xA;" OwnerUserId="169" LastActivityDate="2015-02-09T02:52:08.743" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12556" PostTypeId="2" ParentId="12550" CreationDate="2015-02-09T04:13:03.067" Score="1" Body="&lt;p&gt;In regards to traffic avoidance, unless the airport has a preferred calm wind runway, there's not really a hard and fast rule for which runway you should choose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as you're approaching the airport, you should be looking for traffic both in the pattern and on the field. If there's traffic already in the pattern for a given runway, join that pattern. And, of course, if there's traffic on a runway, don't set up for the same runway in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you've selected a runway, continue to keep your eyes open. You should have a view of the runway for most of the pattern, so you should be able to see if someone without a radio also happens to not look out his window and lines up for departure on the opposite runway. While, as the arriving traffic, you should have the right-of-way over departing traffic, you'd obviously want to break off your approach if the runway is occupied.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-02-09T04:13:03.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12558" PostTypeId="1" AcceptedAnswerId="12560" CreationDate="2015-02-09T07:40:48.877" Score="12" ViewCount="23305" Body="&lt;p&gt;If I recall correctly correctly the vacuum suction gauge in the TB10 has a scale from 3 to 6, with the green range being 4 to 5 (I might slightly off on those numbers though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's clearly marked as showing &lt;a href=&quot;http://en.wikipedia.org/wiki/Inch_of_mercury&quot; rel=&quot;nofollow&quot;&gt;inHg&lt;/a&gt;, but unlike the manifold gauge it's on the lower stop when the engine isn't running (rather than the upper stop if, as the manifold gauge, trying to reach ambient pressure). I haven't really paid attention to it's behavior in the aircraft (only checking that it's in the green), and I just looked at it in Xplane right now which might be wrong of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it showing the negative difference to ambient pressure? Or the difference in pressure before and after the vacuum pump (which may or may not be the same thing)? Or something else completely? :)&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="65" LastEditDate="2015-02-10T14:02:46.673" LastActivityDate="2018-03-08T04:05:30.310" Title="What does the suction gauge actually show?" Tags="&lt;flight-instruments&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12559" PostTypeId="2" ParentId="12551" CreationDate="2015-02-09T09:57:26.233" Score="2" Body="&lt;p&gt;The ball in the turn coordinator is loose, and it wants to stay in the same place as an object at rest wants to stay at rest. When the ball seems to be bouncing around it's actually the airplane bouncing around it due to rough air rather than the aircraft being our of balance relative to the airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you saw at the rudder in rough air you are actually throwing the aircraft out of balance one way and then the other. You can end up over-controlling with coarse rudder inputs and possibly snap-rolling the airplane, although that's unlikely. More likely you will just tire yourself out and waste concentration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep your feet nice and steady on the controls, there's rarely any need for large inputs. When the air is smooth have a glance at the ball and make corrections then. Keep your vision outside the cockpit as much as possible and keep your airspeed up. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-02-09T09:57:26.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12560" PostTypeId="2" ParentId="12558" CreationDate="2015-02-09T12:40:00.457" Score="8" Body="&lt;p&gt;According to the diagram below from a &lt;a href=&quot;http://www.1worldaero.com/app/download/6614576154/TB200PIM.pdf?t=1370899241&quot; rel=&quot;nofollow noreferrer&quot;&gt;TB200 pilots manual&lt;/a&gt; the gauge shows the difference between vacuum line and the ambient pressure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uC3Vx.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure difference between the ambient and the vacuum line drives the airflow which spins the gyros in you instruments. In the Socata design, there is an implicit assumption that the air filter is not blocked. If the filter would be blocked, the suction gauge would probably exceed the green area unless the vacuum relief valve opens before the red is reached. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your vacuum pump stops working, the dial will fall to its lower stop. If the air filter is blocked, and both the vacuum pump and the vacuum relief valve working properly, the dial should exceed 5 inHg.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Other designs are a bit more fault tolerant in the sense that they do not make any assumptions on the working of the filter or the relief valve. In the examples below (thanks to voretaq7) the suction gauge indicates the pressure difference over the instrument itself, which is a more robust presentation of how the system is performing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sXo4N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O3Y48.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-02-10T22:14:57.753" LastActivityDate="2015-02-10T22:14:57.753" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12561" PostTypeId="2" ParentId="12551" CreationDate="2015-02-09T14:25:00.837" Score="1" Body="&lt;p&gt;In a steady wind, even in gusty conditions, the wind direction doesn't change much, except by a few degrees. Its enough to glance at the ball each time you enter a turn and each time you return to straight flight, and make a gentle correction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where things get tricky is when the winds are variable (METAR: 180V240 or VRB005KT), there's wind shear, or there's turbulence, in which case you will be working the stick as well as the rudder to keep the plane on course and coordinated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'd have to get the ball pretty far (at least one ball diameter) out of whack to be dangerous, but your back seat passengers will feel any lack of coordination.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-09T16:25:34.693" LastActivityDate="2015-02-09T16:25:34.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12562" PostTypeId="2" ParentId="12550" CreationDate="2015-02-09T14:52:08.273" Score="6" Body="&lt;p&gt;You can talk about obstacles and runway lengths and not flying into the sun and all sorts of other minutiae that probably don't apply in calm conditions in a Cessna 172.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point you've decided that there's no one in the pattern, but you're going to keep looking for traffic throughout the pattern just like you learned from your CFI, and you have to pick a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me, I'll pick the one that requires the least amount of flying, just like the Hawker 800 pilot will do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that this technique is not for everyone, but if I'm heading southbound, and there's a nice N/S-ish runway, I'll make that straight in, just like it says in &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/1997/April/1/The-great-debate&quot; rel=&quot;noreferrer&quot;&gt;this AOPA article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Straight-in approaches are always a topic for discussion. Under VFR&#xA;  conditions they are acceptable only if there is no conflict with other&#xA;  traffic.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qyCu7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I'm heading southbound, and there's an E/W-ish runway, I'll enter a long L or R base, regardless of which way traffic pattern is. If I care about the traffic pattern for some reason (obstacle or noise abatement), I'll make an overhead entry, which means overfly the airport and enter left or right downwind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're uncomfortable with a straight-in, base, or overhead entry, look for the runway where you can make a downwind or 45 entry with the least amount of maneuvering for L or R traffic as per the chart:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wObg4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-09T15:45:52.677" LastActivityDate="2015-02-09T15:45:52.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12563" PostTypeId="1" CreationDate="2015-02-09T14:54:26.187" Score="7" ViewCount="1131" Body="&lt;p&gt;Suppose Air Canada flies from Vancouver to Santiago with a stop in LAX. I am vaguely of the belief that they are not allowed to pickup Americans who wish to travel from LAX to Santiago, but I'm curious to know more about these rules (if they exist). Also, how they apply (or not) internationally, ie. not just in America.&lt;/p&gt;&#xA;" OwnerUserId="7255" LastEditorUserId="19" LastEditDate="2015-02-09T16:22:30.350" LastActivityDate="2016-03-31T02:53:48.787" Title="What are the rules regarding airlines picking up passengers at stops in foreign countries?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12564" PostTypeId="1" CreationDate="2015-02-09T15:33:16.997" Score="1" ViewCount="99" Body="&lt;p&gt;Yesterday I flew on Airbus A320 and on the airline's board catalogue, there were written some &quot;curiosities&quot;. On was written that the air coming from the air conditioning inside the fuselage is very dry, (3-10% humidity) because while it's warmed up from the freezing outside air, it is much more complicated to humidify it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly I never even thought that our breathable air comes from the outside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;During flight, from where air intake is made in an aircraft? &lt;/li&gt;&#xA;&lt;li&gt;Does this air also contain CO&lt;sub&gt;2&lt;/sub&gt; along with Oxygen dumped directly to the fuselage?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7061" LastEditorUserId="65" LastEditDate="2015-02-09T15:58:19.567" LastActivityDate="2015-02-09T15:58:19.567" Title="How does air enter and leave the cabin of an airliner?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;&lt;oxygen&gt;" AnswerCount="0" CommentCount="3" FavoriteCount="1" ClosedDate="2015-02-09T16:21:40.673" ContentLicense="CC BY-SA 3.0" />
  <row Id="12565" PostTypeId="2" ParentId="12563" CreationDate="2015-02-09T16:13:11.203" Score="11" Body="&lt;p&gt;The short answer to your first question is that an airline can pick up passengers at an intermediate stop as long as it's previously been agreed by all the countries involved (see below). One example is Singapore Airlines SQ12, which flies SIN-NRT-LAX; many passengers leave and board the aircraft in Tokyo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More generally, these rules are known as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Freedoms_of_the_air&quot; rel=&quot;nofollow noreferrer&quot;&gt;freedoms of the air&lt;/a&gt; but they aren't consistently or fully implemented everywhere and a lot depends on agreements between individual countries. Your first question is about the &lt;a href=&quot;http://en.wikipedia.org/wiki/Freedoms_of_the_air#Fifth_freedom&quot; rel=&quot;nofollow noreferrer&quot;&gt;fifth freedom&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the right to fly between two foreign countries on a flight originating&#xA;  or ending in one's own country&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As Wikipedia describes, this isn't always straightforward:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The negotiations for fifth freedom traffic rights can be lengthy&#xA;  because in practice the approval of at least three different nations&#xA;  is required&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If an airline stops in an intermediate country to refuel or for other technical reasons but isn't allowed to board or deplane customers, that would be the &lt;a href=&quot;http://en.wikipedia.org/wiki/Freedoms_of_the_air#Second_freedom&quot; rel=&quot;nofollow noreferrer&quot;&gt;second freedom&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the right to refuel or carry out maintenance in a foreign country&#xA;  without embarking or disembarking passengers or cargo&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's an interesting discussion of fifth freedom flights from a passenger perspective &lt;a href=&quot;http://onemileatatime.boardingarea.com/2014/10/31/what-is-a-fifth-freedom-flight/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, and you may get better answers on this topic on &lt;a href=&quot;https://travel.stackexchange.com/&quot;&gt;travel.SE&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2015-02-09T18:52:45.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12566" PostTypeId="1" AcceptedAnswerId="12567" CreationDate="2015-02-09T19:41:09.380" Score="9" ViewCount="1821" Body="&lt;p&gt;I know that fuel filters on aircraft engines have some features that avoid the bowl from detachment during flight, and that they can be secured using safety wire as shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K2N9j.jpg&quot; alt=&quot;Safetied gascolator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also heard that installing safety wire is very time consuming. Is that true?&lt;br&gt;&#xA;What is your experience with installation &amp;amp; safetying of fuel filter bowls?&lt;/p&gt;&#xA;" OwnerUserId="7263" LastEditorUserId="64" LastEditDate="2015-02-09T20:12:15.830" LastActivityDate="2015-02-10T12:06:56.260" Title="Does a safety wire prevent a fuel filter to detach during flight?" Tags="&lt;fuel&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12567" PostTypeId="2" ParentId="12566" CreationDate="2015-02-09T19:57:40.997" Score="16" Body="&lt;p&gt;Safety wire is almost never &quot;efficient&quot;, but efficiency is not the goal: Safety is.&lt;br&gt;&#xA;You want to be certain that once the fuel strainer has been secured it's not going to fall off in flight (which will result in the engine being starved of fuel).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On many light aircraft that's accomplished by wrapping safety wire on the fuel strainer to ensure it can't come loose in flight:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/3JGOk.png&quot; alt=&quot;Fuel strainer safety wiring&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A skilled mechanic who works with safety wire every day can safety a fuel strainer in about a minute - probably even faster. It's pretty impressive to watch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A bungling incompetent like me who does it maybe once a year takes about 5 minutes, often punctuated with &quot;colorful metaphors&quot; and comments about the questionable parentage of the engineer responsible for the fuel strainer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, in the grand scheme of things that's not a lot of time spent on securing a flight-critical component.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Because there are far more bungling incompetents than skilled mechanics (and because even good mechanics are frequently not fond of safety wire) there are &lt;a href=&quot;http://www.stevesaircraft.com/gascolator.php&quot; rel=&quot;noreferrer&quot;&gt;other fuel strainer designs&lt;/a&gt; which don't use safety wire.&lt;br&gt;&#xA;The one I linked to uses a bayonet lock for the bowl, and a cotter pin to keep it from coming loose in flight. Anyone can bend a cotter pin in a couple of seconds, and as effective as the safety wire technique, if not moreso.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-09T19:57:40.997" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12568" PostTypeId="2" ParentId="484" CreationDate="2015-02-09T21:10:20.670" Score="0" Body="&lt;p&gt;On wings they are called tufts, and are a means of 2D-flow visualization. The yaw string just shows the yaw angle at a single location. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has a picture with tufts attached to a winglet &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Winglet_with_attached_tufts_of_an_KC-135A.jpg&quot; rel=&quot;nofollow&quot;&gt;Winglet with attached tufts of an KC-135A&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorDisplayName="user7241" LastEditDate="2015-02-10T16:20:14.400" LastActivityDate="2015-02-10T16:20:14.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12569" PostTypeId="2" ParentId="12541" CreationDate="2015-02-09T21:23:14.877" Score="26" Body="&lt;p&gt;I know there is already an accepted answer, but some key facts are missing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mainly, the optimum cruise altitude is where thrust and lift requirements for both take-off and cruise balance well. An additional benefit is the cooler air which increases the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;efficiency of heat engines&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With increasing flight altitude, the airliner needs:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Bigger engines to create the needed thrust in thinner air&lt;/li&gt;&#xA;&lt;li&gt;Bigger wings to create the needed lift&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With the wings, the size of the tailplanes will also grow; this effect alone likely will weigh more than the beefing up of the fuselage structure for the increased cabin pressure. Flying higher will make almost all parts bigger and heavier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85/11948#11948&quot;&gt;Mach 0.85 is a hard limit&lt;/a&gt; for efficient flight; airliners cannot compensate for lower density by flying faster. The only way to allow higher flight levels is to attach bigger wings and tails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another consideration is Breguet's formula: Jet aircraft have their &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;optimum cruise lift coefficient&lt;/a&gt; at a value of $c_L = \sqrt{0.6\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$, if we assume the thrust of high-bypass-ratio engines to vary with speed proportional to $v^{-0.5}$, which is a reasonable assumption. This means the airliner cannot fly higher by flying at a higher lift coefficient: This would decrease efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Nomenclature: $c_{D0}$ = zero-lift drag, $AR$ = wing aspect ratio, $\epsilon$ = span efficiency)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the wing size and the engines needed for flight at Mach 0.82 in the tropopause (Mach 0.85 is really not as efficient; follow &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85/11948#11948&quot;&gt;the link&lt;/a&gt; to find out why this is the quoted cruise speed for long-range airliners), the take-off distance is quite reasonable and approximately matches the airports which had been defined by NATO during the cold war. Flying any higher into the stratosphere would increase the aircraft's mass due to bigger engines and wings, but would not incur the efficiency gains of increasing cruise altitude in the troposphere, where temperature drops with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, picking a lower design cruise altitude would allow to make both wings and engines smaller, but this would translate into:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Higher take-off and landing speeds, and critical speeds during take-off due to the smaller wing,&lt;/li&gt;&#xA;&lt;li&gt;Lower take-off acceleration due to smaller engines,&lt;/li&gt;&#xA;&lt;li&gt;For twins: Not enough thrust during take-off when one engine fails,&lt;/li&gt;&#xA;&lt;li&gt;Lower climb speeds, so it would take longer to reach cruise altitude, and&lt;/li&gt;&#xA;&lt;li&gt;Not fully taking advantage of the cold air up in the tropopause.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Designing for a lower cruise altitude would translate into much longer runways and less efficient flight overall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designing for cruise in the tropopause is simply the sweet spot for airliner designers where all conditions match well and produce a balanced outcome.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-06-24T08:49:57.127" LastActivityDate="2017-06-24T08:49:57.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12570" PostTypeId="2" ParentId="367" CreationDate="2015-02-09T22:19:01.293" Score="3" Body="&lt;p&gt;I would expand a little bit more the answer. Firstly you are talking about anti-icing systems. Actually there are 2 kind of devices that provide protection agaisnt icing, from one side the anti-icing systems, like heaters, and de-icing systems, once iced is created the systems destroys it. For example, F17 used de-icing boots on the horizontal plane, so it was not using anti-icing. ATR72 is another example of de-icing systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I think your question is actually why some airplanes are not using ice protection systems (both de-ice and anti-ice) on horizontal planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is clear: because is cheaper to have a bigger tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's recall what's the horizontal plane is doing, its function is basically providing balance to the airplane and supporting maniouvres in flight, like for example take-off, recover from a failed landing...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When designing an horizontal tail plane you need to consider all potential maniouvres that the plane needs to answer to. One of those conditions need to be possible with the presence of ice or having a system avoiding having ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to provide the same performances, either you have a system that avoids having ice or very few or you have a bigger plane. On top you have other conditions which are dimensioning the plane, like flutter or other maniouvres.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Either was lighter having a bigger plane that operates safely with ice than a smaller plane with ice protecution&lt;/li&gt;&#xA;&lt;li&gt;Or there was another condition in the design that was already making the plane big enough to operate safely with ice, making the ice protection system not mandatory and so not needed weight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To be honest, I can't tell you for each airplane which was the dimensioning condition that eliminated the need of ice protection.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-02-09T22:19:01.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12571" PostTypeId="1" CreationDate="2015-02-09T22:37:55.670" Score="2" ViewCount="839" Body="&lt;p&gt;What is the meaning of the &lt;strong&gt;track&lt;/strong&gt; info found on Flightradar24, as seen below?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would be the angle between the route and the equator?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o7fiG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7230" LastActivityDate="2015-02-10T01:49:35.623" Title="Flightradar24.com track info" Tags="&lt;online-tracking&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ClosedDate="2015-02-10T07:34:40.393" ContentLicense="CC BY-SA 3.0" />
  <row Id="12572" PostTypeId="1" AcceptedAnswerId="12576" CreationDate="2015-02-09T23:27:36.987" Score="8" ViewCount="7611" Body="&lt;p&gt;I'm trying to use a simulator to learn to land properly.  One part that I'm finding really tricky is picking a proper rate of descent.  I know I'm supposed to do my best to keep it so I have two red lights and two white lights on the Precision Approach Path Indicator (PAPI), but at the moment I basically am just eyeballing it and adjusting my course whenever the lights aren't right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have to assume, though, that for any given airspeed there is a rate of descent I can maintain that will keep me right in the middle of the preferred glide slope for that airport.  I just have no idea how to figure it out.  Is there an application or formula that is preferred for this?  Or is it time to learn Vector Calculus?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS- I did check &lt;a href=&quot;https://aviation.stackexchange.com/questions/1971/descent-planning&quot;&gt;this&lt;/a&gt; question to see if it related.  But that question is about starting the descent from cruise.  I'm talking about rate of descent for final. I did also check &lt;a href=&quot;https://aviation.stackexchange.com/questions/5086/how-to-get-the-correct-angle-when-doing-a-visual-appoach-before-landing&quot;&gt;this&lt;/a&gt; answer, but it's about using the PAPI/VASI lights.  I'm looking for a formula to figure out the proper rate of descent during final for a given speed.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-02-10T18:31:05.823" Title="How do you determine the proper rate of descent for landing?" Tags="&lt;landing&gt;&lt;visual-approaches&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12573" PostTypeId="1" AcceptedAnswerId="12574" CreationDate="2015-02-09T23:30:58.197" Score="13" ViewCount="6117" Body="&lt;p&gt;I figured this was probably a no brainer, since Europe uses the metric system, I assume the airspace does...  But then I remembered that aviation likes international standards, and I know the US uses Imperial so, does Europe as well?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, yes or no, why do they take that choice?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="7230" LastEditDate="2015-02-09T23:40:06.837" LastActivityDate="2015-02-10T12:31:52.493" Title="Does European airspace use the metric system?" Tags="&lt;easa-regulations&gt;&lt;measurement&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12574" PostTypeId="2" ParentId="12573" CreationDate="2015-02-09T23:35:43.090" Score="18" Body="&lt;p&gt;European Civil Aviation Authorities use the imperial system to depict altitudes and airspace restrictions (feet), speeds (knots) and distances (nautical miles).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some VFR aircraft have speed indicators in km/h, gliders can have altitude and variometer in meters and meters/second and apart from a special ICAO VFR chart being available in metric in Germany, the AIP itself and all other charts always use imperial units.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/2566/what-is-the-measurement-system-used-in-the-aviation-industry&quot;&gt;What is the measurement system used in the aviation industry?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-02-09T23:35:43.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12575" PostTypeId="2" ParentId="12572" CreationDate="2015-02-10T00:02:12.250" Score="1" Body="&lt;p&gt;For most purposes, if you're flying something with a jet engine, you can probably schwag -700fpm for a 3 degree glideslope and be fairly accurate.  It will at least give you a starting point.  You shouldn't be flying the approach solely off your VSI anyway, but it is useful to determine how large of a correction you are making, or if you're about to bust through the bottom.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-02-10T04:08:54.287" LastActivityDate="2015-02-10T04:08:54.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12576" PostTypeId="2" ParentId="12572" CreationDate="2015-02-10T00:07:20.007" Score="8" Body="&lt;p&gt;Assuming you want a 3 degree glide slope, just take 5 times your ground speed in knots as a starting point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, approaching at 90kt ground speed in a light aircraft, go for 450feet per minute. at 140kt in a jet, try 700fpm. If you're flying a jet outside of 4 miles, and the controller wants you to keep the speed up at 200kt then descend 1000fpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not perfect, but it works pretty well for a first guess, and you can adjust as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, your ground speed is not the same as your air speed, and even for a constant IAS it will likely vary as you descend and the wind changes. Another way to think about this is that a 3 degree glideslope is almost exactly 300ft per nautical mile. If you're 2 miles out and 700 feet up, then you need to descend a bit faster, conversely, if you're at 500 feet, you need to descend slower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A third related rule of thumb is that your final approach speed (in CAS, although IAS is good enough in most aircraft) is 1.3 times your stall speed in the landing configuration (Vso). So if you stall at 100 knots, you want to approach at 130KIAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR approaches are all about having an initial guess at these numbers in your head, trying them out, and then adjusting as the conditions require. If you're good at the guesses then the adjustments will be very small.&lt;/p&gt;&#xA;" OwnerUserId="2586" LastEditorUserId="2586" LastEditDate="2015-02-10T00:14:52.750" LastActivityDate="2015-02-10T00:14:52.750" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12577" PostTypeId="2" ParentId="12573" CreationDate="2015-02-10T00:18:21.900" Score="14" Body="&lt;p&gt;Europe uses imperial for distance (nm), speed (knots) and altitude (feet). Russia and China are the only major countries that use meters for altitude - and it causes all sorts of confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft (more in europe) use kilometers and statute miles/hour on the ASI - but the same is true in the US.&lt;/p&gt;&#xA;" OwnerUserId="2586" LastActivityDate="2015-02-10T00:18:21.900" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12578" PostTypeId="2" ParentId="12571" CreationDate="2015-02-10T00:22:18.327" Score="5" Body="&lt;p&gt;That is the angle between true north and the current ground track. FR24 is slightly different to (most) aviation in that it uses true north instead of magnetic north as the datum.&lt;/p&gt;&#xA;" OwnerUserId="2586" LastActivityDate="2015-02-10T00:22:18.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12579" PostTypeId="2" ParentId="12571" CreationDate="2015-02-10T01:49:35.623" Score="1" Body="&lt;p&gt;Track is the heading the aircraft is actually tracking over the earth's surface. This is different from the heading that the aircraft is flying, as wind does change the directional component over the earths surface.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-02-10T01:49:35.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12580" PostTypeId="1" CreationDate="2015-02-10T04:26:05.120" Score="3" ViewCount="416" Body="&lt;p&gt;If I wanted to design an aircraft for autonomous operation and maximum endurance, what design philosophies provide the greatest benefit?  I'm imagining a powered glider.  Does not have to be highly maneuverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in relative proportions, wingspan, length, center of gravity, center of pressure, wing placement, dihedral/anhedral, engine placement, fuel type, etc.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there a &quot;sweet spot&quot; for center of gravity relative to center of lift so as to maximize stability?  &lt;/li&gt;&#xA;&lt;li&gt;Since it will be mostly autonomous (computer-controlled), can I design for less inherent stability?&lt;/li&gt;&#xA;&lt;li&gt;What engines/fuel types are the most efficient?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-03-17T19:52:58.300" Title="What aircraft design elements contribute the most to sustained flight?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;cg&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12581" PostTypeId="1" AcceptedAnswerId="12606" CreationDate="2015-02-10T05:43:37.187" Score="9" ViewCount="6535" Body="&lt;p&gt;I am wondering how Victor airways get determined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What determines how many 'segments' they are? For example some airways connect two VORs only, while other airways stretch across (or &quot;connect the dots&quot; of) many VORs as they snake across the map.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, is there a numbering scheme? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;U.S. freeways have a numbering pattern. For example, odd numbered roads run North/South, with their names increasing in magnitude from West to East (I-5 runs from Seattle to San Diego; I-95 runs from Maine to Miami). Is there anything like that in Victor airway system?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-02-11T00:05:30.743" Title="How are Victor airways defined and numbered?" Tags="&lt;navigation&gt;&lt;aeronautical-charts&gt;&lt;navaids&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12582" PostTypeId="1" CreationDate="2015-02-10T09:17:34.520" Score="5" ViewCount="1846" Body="&lt;p&gt;I found a lot of references to the question but no definite simple answer.&#xA;What would be the influence on &lt;a href=&quot;http://en.wikipedia.org/wiki/True_airspeed&quot;&gt;true airspeed&lt;/a&gt; (TAS) for same airplane at same throttle setting flying straight and level at higher altitude?&#xA;Would it change for Jet engine vs internal combustion engine?&lt;/p&gt;&#xA;" OwnerUserId="7271" LastEditorUserId="62" LastEditDate="2015-02-10T13:54:39.650" LastActivityDate="2015-02-11T11:02:25.823" Title="At a constant power setting, does TAS change with altitude?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12584" PostTypeId="2" ParentId="12496" CreationDate="2015-02-10T10:26:03.667" Score="16" Body="&lt;p&gt;The FAA standards seem to anticipate the use of firearms by people attempting to gain unlawful access to the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Opening locks with firearms is probably not as successful as TV would have you believe.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Cockpit Door Standards&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Press Release – FAA Sets New Standards for Cockpit Doors&lt;br&gt;&#xA;  Release No. APA 01-02&lt;br&gt;&#xA;  January 11, 2002&lt;br&gt;&#xA;  Contact: Alison Duquette  Phone: 202-267-3462 WASHINGTON, DC&lt;br&gt;&#xA;  In response to President Bush's call to strengthen aircraft security, the&#xA;  U.S. Department of Transportation's Federal Aviation Administration&#xA;  (FAA) today published new standards to &lt;strong&gt;protect cockpits from intrusion&#xA;  and small arms fire&lt;/strong&gt; or fragmentation devices, such as grenades. The&#xA;  Aviation and Transportation Security Act authorizes the FAA to issue&#xA;  today's final rule that requires operators of more than 6,000&#xA;  airplanes to install reinforced doors by April 9, 2003.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.faa.gov/news/press_releases/news_story.cfm?newsId=5470&quot;&gt;FAA Press Release&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This press release doesn't actually say that the locks on the doors must resist being fired on using handguns but it is apparent that the scenarios envisaged included those where handguns were present. There are obviously other measures to prevent passengers carrying combat shotguns into the cabin surreptitiously.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Guns and Locks&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In movies and television, a locked door, or a padlock on a cage is never an impediment so long as the Hero has bullets to spare. One or two shots is generally enough to destroy the lock, allowing the door to open.&#xA;  Unfortunately, in real life — as shown by the MythBusters — this requires a high powered gun at close range, which causes lots of very dangerous shrapnel. Lesser firearms, especially handguns may harmlessly bury rounds in even standard padlocks to little effect. Only SWAT teams and soldiers ever do this in real life, and it involves a shotgun, Kevlar body armor, specialized ammunition (a powdered metal breaching round, often jokingly referred to as &quot;Avon Calling&quot;), and full face protection. Even then, the goal is not specifically to destroy the lock, but to destroy the surrounding door or the hinges. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://tvtropes.org/pmwiki/pmwiki.php/Main/ShootOutTheLock&quot;&gt;TvTropes Shoot out the lock&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Other references&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://videos.howstuffworks.com/discovery/32917-mythbusters-shooting-locks-video.htm&quot;&gt;Mythbusters - shooting locks&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-02-10T10:33:56.627" LastActivityDate="2015-02-10T10:33:56.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12585" PostTypeId="2" ParentId="3367" CreationDate="2015-02-10T10:50:16.637" Score="13" Body="&lt;p&gt;An Australian company I used to work for purchased a Jetstream 41 turboprop off an American seller. With a range of only about 1400 kilometres, there was no chance of safely making it across the Pacific. So the ferry flight went through Canada, Alaska, Russia, right down through south Asia to northen Australia. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer is, when they can't extend the range far enough, they'll go the long way!! &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-02-10T10:50:16.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12586" PostTypeId="2" ParentId="12573" CreationDate="2015-02-10T11:22:55.413" Score="6" Body="&lt;p&gt;As others have mentioned, the basic units to define the airspace are feet and nautical miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some other values are also used when navigating the airspace, and a few are from the SI system. For instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;pressure settings: hPa (aka millibars, mbar) &lt;/li&gt;&#xA;&lt;li&gt;runway lengths: meters&lt;/li&gt;&#xA;&lt;li&gt;visibility: meters&lt;/li&gt;&#xA;&lt;li&gt;temperature: centigrades&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Regulations (VFR):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;minimum horizontal distance from obstacles: meters&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To see the SI units for pressure, visibility and temperature in a real-life setting, just have a look at a TAF/METAR for any European airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mixture of units can seem strange, but there is also a method to the madness. You know that whenever you hear a measurement in feet, it is about a vertical distance, and  anything expressed in meters (or kilometers) will be horizontal. A small contribution to the clarity of communications. &lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="2176" LastEditDate="2015-02-10T12:31:52.493" LastActivityDate="2015-02-10T12:31:52.493" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12587" PostTypeId="2" ParentId="3367" CreationDate="2015-02-10T11:51:20.510" Score="7" Body="&lt;p&gt;I was chatting to one of the Pilots of &lt;a href=&quot;http://en.wikipedia.org/wiki/Maldivian_Air_Taxi&quot; rel=&quot;noreferrer&quot;&gt;Maldivian Air Taxi&lt;/a&gt; a number of years ago, who fly Canadian built Twin Otter's. He remarked that one of the more interesting jobs for that carrier was the &quot;Overhaul flights&quot;. A few pilots spend almost all year ferrying their aircraft back and forth to Canada. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't remember the exact route but it involved lots and lots of stop-offs for fuel.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-02-10T11:51:20.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12588" PostTypeId="1" AcceptedAnswerId="12591" CreationDate="2015-02-10T11:57:31.343" Score="18" ViewCount="7092" Body="&lt;p&gt;Recently I was flying on an Airbus A320. While cruising around 37,000 feet, I noticed half of the glass on the window had frozen. But it was a thin layer of ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was it anything to be concerned about? Should I have brought it to the notice of the airline crew?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Ice formed on the inside of window with a small hole in it. I guess it was the middle layer of glass.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-10-07T14:36:46.387" LastActivityDate="2015-10-07T14:36:46.387" Title="Is freezing of windows normal in airlines?" Tags="&lt;airliner&gt;&lt;airbus-a320&gt;&lt;icing&gt;&lt;windows&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12589" PostTypeId="2" ParentId="12582" CreationDate="2015-02-10T12:53:19.283" Score="0" Body="&lt;p&gt;The true airspeed (TAS) is determined by adjusting the indicated airpseed (IAS) for altitude and outside air temperature (OAT). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Faster small airplanes have a TAS calculator built in to the ASI. To use it, the pilot dials in the pressure altitude read off the altimeter (ALT), and sometimes the OAT, and reads the TAS off a separate dial on the ASI. In this photo, the IAS is 105kts, and the TAS is 129kts @14,000ft, 147kts at 16,000, 164kts @ 18,000ft, 182kts @ 20,000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In one airplane I fly, the cruise setting is 34&quot; MP and 2400 RPM. This setting produces a higher TAS at higher altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/r0eUU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airplanes that don't have such a dial, the pilot can estimate the TAS by adding 2% per 1,000ft of altitude to the IAS. For example, 100kts IAS at 10,000 ft pressure altitude is 100kts * 20% = 20kts. So the TAS would be 120 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;True airspeed calculations become less accurate as altitude increases and the planes flies faster, but a jet and a plane both flying at the same indicated airspeed at 10,000ft will read the same TAS off the dial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher altitudes, jets and turboprops use an &quot;air data computer,&quot; such as &lt;a href=&quot;http://www.cwc-ae.com/rugged-computers-switches-learn-more/what-air-data-computer&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;, which states: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air data computers are used by aircraft to acquire and process data&#xA;  from sensors (such as pitot tubes and avionics buses) to obtain key&#xA;  air data parameters such as altitude, airspeed, height deviation and&#xA;  temperature to ensure safe and accurate flight detail, on both rotary&#xA;  and fixed wing aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-02-10T14:11:46.093" LastActivityDate="2015-02-10T14:11:46.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12590" PostTypeId="2" ParentId="12588" CreationDate="2015-02-10T13:39:49.637" Score="4" Body="&lt;p&gt;It is something normal, airplanes are flying at -40º outside and is very common that ice is generated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to be aware that some parts of the airplane which are critical for having a safe flight are having ice protection systems to avoid generation, but ice in the windows is just avoiding you to have a nice view and enjoy the views. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not a big deal.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="65" LastEditDate="2015-02-10T14:32:17.467" LastActivityDate="2015-02-10T14:32:17.467" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12591" PostTypeId="2" ParentId="12588" CreationDate="2015-02-10T13:42:09.903" Score="29" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Was it anything to be concerned&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Should I have brought it to the notice of the airline crew?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, but not because it is a safety issue. Tell them so they can deal with it to give the next passenger a nicer experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is happening is no different than a glass of ice water sitting on your kitchen counter. The warmer side of the glass (the outside) becomes cooler because of the cold on the inside and it transfers that coolness to the surrounding air. That surrounding air cools enough to cause the moisture it contained to condense into liquid that sticks to your glass. If the glass were cold enough, it would freeze that condensation. The window on the aircraft is that cold so the condensation freezes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a mechanism under the window to keep this from happening. It is a jar of &lt;a href=&quot;http://en.wikipedia.org/wiki/Desiccant&quot;&gt;desiccant&lt;/a&gt; that absorbs all moisture (dries the air) in the window area so that there is no moisture to condense in the first place. Often, there is a tiny bit still.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the desiccant absorbs moisture from the air, it retains it. So periodically, it gets saturated to the point it can't absorb anymore and the desiccant needs to be changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either the desiccant in your window needed to be changed or moist air is bypassing the desiccant on its way to the inside surface of the window. Normally there is a seal between the outside window and that thin plastic window you can touch and the only way for air to get in or out of that inter-window area is through the desiccant. Your window may have a broken seal allowing moist air to bypass the desiccant. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, it is a system designed only to keep the window from forming ice so the passengers can look out the window, it has no safety or structural consequences.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="65" LastEditDate="2015-02-10T14:38:11.963" LastActivityDate="2015-02-10T14:38:11.963" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12592" PostTypeId="2" ParentId="12582" CreationDate="2015-02-10T14:16:03.103" Score="1" Body="&lt;p&gt;The answer to your question largely depends on what you mean by &quot;constant throttle setting&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For propeller propulsion, if &quot;constant throttle setting&quot; means &quot;constant power setting&quot; as in a fixed output BHP, TAS will increase almost linearly with altitude (up to the altitude where constant power output can no longer be maintained).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a normally aspirated reciprocating engine with a fixed pitch propeller, a constant throttle position will mean a decreased manifold pressure with increased altitude resulting in less power output, less thrust (T), and thus decreasing TAS (assuming the decrease in thrust is larger than the decrease in drag (D) resulting from the decreased density at higher altitude, this generally holds true). For a supercharged engine, depending on how the supercharger is controlled, &quot;constant throttle setting&quot; can have the charge control maintain a constant manifold pressure. In this case, the power setting will be maintained (up to the maximum altitude where the supercharger can maintain the manifold pressure), and TAS will increase.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a jet propulsion engine, once again it depends on what is implied with &quot;constant thrust setting&quot;. For example, for low/no bypass engines, a constant EPR should roughly correspond to constant T with altitude, hence with D decreasing with altitude, TAS will be higher before T = D. If &quot;constant thrust&quot; means &quot;constant N1&quot;, thrust will actually decrease with altitude, how quickly it decreases with altitude will determine the effect on TAS (once again, where T = D).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If &quot;constant throttle setting&quot; simply implies &quot;constant thrust&quot;. Resulting TAS will always be higher (as for a given TAS, T remains constant and D once again decreases).&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-02-11T11:02:25.823" LastActivityDate="2015-02-11T11:02:25.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12593" PostTypeId="2" ParentId="8391" CreationDate="2015-02-10T14:42:52.850" Score="21" Body="&lt;p&gt;In &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Bernstein_of_Leigh_v_Skyviews_%26_General_Ltd&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bernstein of Leigh v Skyviews&lt;/a&gt;&lt;/em&gt; &lt;a href=&quot;http://www.bailii.org/ew/cases/EWHC/QB/1977/1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;[1978] 1 QB 479&lt;/a&gt;, the High Court of England and Wales held that, at common law, the right of a landowner to the airspace above their land was &amp;quot;to such height as was necessary for the ordinary use and enjoyment of his land and the structures upon it&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;As another answer has suggested, the use of UK airspace is now regulated by statute.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.legislation.gov.uk/ukpga/1982/16/section/76&quot; rel=&quot;nofollow noreferrer&quot;&gt;Section 76 of the Civil Aviation Act 1982&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No action shall lie in respect of trespass or in respect of nuisance, by reason only of the flight of an aircraft over any property at a height above the ground which, having regard to wind, weather and all the circumstances of the case is reasonable, or the ordinary incidents of such flight, so long as the provisions of any Air Navigation Order and of any orders under section 62 above have been duly complied with and there has been no breach of section 81 below.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In other words, you may fly an aircraft at a height that is reasonable, subject to any specific regulations.&lt;/p&gt;&#xA;&lt;p&gt;For example, rule 5 in &lt;a href=&quot;http://www.legislation.gov.uk/uksi/2007/734/schedule/1/made&quot; rel=&quot;nofollow noreferrer&quot;&gt;schedule 1 of the Rules of the Air Regulation 2007&lt;/a&gt; prohibits low flying in certain circumstances, such as below 1,000 feet over a congested area of a city, although there are various exemptions to those rules. For the detail, consult the regulations. &lt;em&gt;Update:&lt;/em&gt; This is now rule 5 in &lt;a href=&quot;https://www.legislation.gov.uk/uksi/2015/840/schedule/1/paragraph/5/made&quot; rel=&quot;nofollow noreferrer&quot;&gt;schedule 1 of the Rules of the Air Regulation 2015&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;What this means in terms of a landowner's right is that:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;their rights do not extend beyond what is &amp;quot;necessary...&amp;quot; in accordance with &lt;em&gt;Bernstein of Leigh&lt;/em&gt; whatever the specific rules on aircraft may say&lt;/li&gt;&#xA;&lt;li&gt;additionally, the landowner's rights are restricted by the CAA and the rules made under it, so that an aircraft that complies with the rules and flies no lower than is reasonable etc does not commit a trespass or nuisance.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7275" LastEditorUserId="7275" LastEditDate="2021-04-10T21:13:07.337" LastActivityDate="2021-04-10T21:13:07.337" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="12594" PostTypeId="1" AcceptedAnswerId="12595" CreationDate="2015-02-10T16:02:17.193" Score="6" ViewCount="579" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.ubergizmo.com/2011/04/flynano-plane/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; (somewhat dubious looking article):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Since it is so light, the FlyNano falls under the weight of what is considered to be a plane, so in most countries you won't need a flying license to take this baby to the skies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2335" LastEditorUserId="755" LastEditDate="2015-02-10T17:11:55.513" LastActivityDate="2015-02-10T17:11:55.513" Title="What is the weight at which an aircraft no longer requires a licensed pilot on board in Europe?" Tags="&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12595" PostTypeId="2" ParentId="12594" CreationDate="2015-02-10T16:28:48.847" Score="4" Body="&lt;p&gt;The aircraft weight needs to be &lt;strong&gt;70 kg&lt;/strong&gt; or less. FlyNano mentioned this on their &lt;a href=&quot;http://www.flynano.com/faq.htm&quot; rel=&quot;nofollow&quot;&gt;FAQs page&lt;/a&gt; (&lt;em&gt;my paraphrasing&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do I need a pilot's license to operate FlyNano?&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;According to the &lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/ALL/;ELX_SESSIONID=vFcfJhvJ1mdjTLgsmf0c1pDYgVWChtskKmQCyrw2Vvn4vNsMG2hG!1622802082?uri=CELEX:32008R0216&quot; rel=&quot;nofollow&quot;&gt;European Aviation Safety Association regulation&lt;/a&gt;&#xA;  ... FlyNano is below the necessary weight of 70kg ... In Finland for&#xA;  example no classification, &lt;strong&gt;no aviation license or medical&#xA;  certification are needed&lt;/strong&gt;. But skill is needed. Nevertheless a good&#xA;  understanding of water plane operation, rules and aviation safety is&#xA;  requested. ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I found that &lt;a href=&quot;https://www.iaa.ie/index.jsp?p=102&amp;amp;n=387&amp;amp;a=0&quot; rel=&quot;nofollow&quot;&gt;any aircraft less than 70kg is not affected by EASA regulations&lt;/a&gt;. But regardless, and emphasized by FlyNano also, pilot skills are required.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-10T16:28:48.847" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12597" PostTypeId="2" ParentId="12581" CreationDate="2015-02-10T16:43:31.817" Score="0" Body="&lt;p&gt;I found a bunch of assertions that Victor numbering is even east/west and odd north/south, but haven't found a canonical source. The closest I found is an &lt;a href=&quot;https://books.google.com/books?id=cHKgpO4Q0Q4C&amp;amp;pg=PA8&amp;amp;lpg=PA8&amp;amp;dq=victor%20airways%20east%20west%20numbering&amp;amp;source=bl&amp;amp;ots=cG5ant_WtE&amp;amp;sig=zNklj3czUBbjNNFDPFx7YMhjyoo&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=DzPaVKKyFoOtyQTTo4GgBg&amp;amp;ved=0CDIQ6AEwAw#v=onepage&amp;amp;q=victor%20airways%20east%20west%20numbering&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;excerpt on page 8&lt;/a&gt; from Billy Robbins' &quot;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0595393780&quot; rel=&quot;nofollow&quot;&gt;Air Cops: A Personal History of Air Traffic Contro&lt;/a&gt;l&quot; (which looks really cool). Robbins says that the Victor airways were based on older LF airways, which were color-coded and numbered. The Victor airways went in over time as the LF airways were decommissioned. The excerpt doesn't mention it, but the FAA has periodically updated the Victor network as they have added and removed VORs. &lt;/p&gt;&#xA;" OwnerUserId="7023" LastActivityDate="2015-02-10T16:43:31.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12598" PostTypeId="2" ParentId="12572" CreationDate="2015-02-10T18:31:05.823" Score="1" Body="&lt;p&gt;It helps to know the pitch and power settings for your jet.  That way you're not chasing the airspeed, VVI, etc.  So how do we figure out what pitch and power settings to use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well if we look at our ADI in level-flight at our final approach speed we see we are 2 degree nose-high for example.  And we know that for each degree of pitch change it equates to 100 ft/NM.  With an average ILS the glideslope is around 3 degrees.  So we know that this is about 3 degrees low from our 2 degree level flight attitude.  This leaves us with about 1 degree nose-low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly the approach at 1 degree nose-low, and adjust your power to maintain your airspeed which in the end should result in a VV of about 5 * your groundspeed.  Or you can take your groundspeed and convert it to NM/min and then multiply that by 300 ft/NM.  If we approach at 160 KTS (2.67 NM/min), we end up with a VV of 800 ft/min which is the same as using our rule of thumb of 5 times your groundspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know this is probably a little more math than what you wanted, but setting a known pitch and power setting and making minor adjustments from that will help improve your approaches tremendously.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-10T18:31:05.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12599" PostTypeId="1" CreationDate="2015-02-10T19:14:49.497" Score="5" ViewCount="735" Body="&lt;p&gt;&lt;a href=&quot;http://www.telegraph.co.uk/travel/travelnews/9925121/Does-the-brace-position-save-lives.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;: &lt;em&gt;Does the brace position save lives?&lt;/em&gt;,  By Oliver Smith, 2013 Mar 13, telegraph.co.uk&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;quot;To adopt the brace position passengers should place their feet and knees together with their feet firmly on the floor,” added [Steve Allright, a British Airways training captain] .... “Feet should be flat or on the balls of their feet, and further back than the knees. In the event of an impact, this position helps prevent shins and legs being broken against the base of the seat in front, which would obviously hinder evacuation.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;Passengers should bend as far forward as possible, if it's in reach, they should rest their head against the seat in front, with hands placed on the back of their head. &lt;strong&gt;Hands should be placed on top of one another&lt;/strong&gt; &lt;em&gt;&lt;strong&gt;(not with fingers interlocked)&lt;/strong&gt;&lt;/em&gt; [emphasis mine; this seems a critical fact], elbows should be tucked in to their sides. The head should be as far below the top of the seats as possible. This position prevents flailing of the arms, minimises the risk of broken fingers and protects the head from moving objects.”&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;The position varies slightly in the US. Rather than placing hands on the back of the head, passengers are advised to place them on top of the seat in front, or to hold their ankles.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;1. Why the difference in the hands' position? Which is more protective?&lt;/p&gt;&#xA;&lt;p&gt;2. What does it mean to 'hold their ankles' with the hands? Simply place your hands atop your ankles?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-10T20:13:42.950" Title="Brace position - Why hands atop head in the UK, but on ankles or atop seat in front in the US?" Tags="&lt;emergency&gt;&lt;passenger&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12600" PostTypeId="1" AcceptedAnswerId="12603" CreationDate="2015-02-10T19:17:57.650" Score="2" ViewCount="778" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2572/why-doesnt-the-aviation-industry-use-si-units&quot;&gt;Why doesn't the aviation industry use SI units?&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I believe only a few countries use meters and other SI units in air transportation, including India and China (please correct if wrong).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using kts and NM in navy -- built from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Nautical_mile&quot; rel=&quot;nofollow noreferrer&quot;&gt;length of the 1' arc&lt;/a&gt; on a meridian -- simplified nautical mental arithmetic, and likely also helped at the beginning of aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Current ICAO recommendations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Annex 5 - &lt;a href=&quot;http://cockpitdata.com/Software/ICAO%20Annex%205&quot; rel=&quot;nofollow noreferrer&quot;&gt;Units of Measurement to be Used in Air and Ground Operations&lt;/a&gt;, ICAO allows 3 non-SI units (knot, foot, nautical mile) to be used...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;as alternative units because of their widespread use and to avoid&#xA;  potential safety problems which could result from the lack of&#xA;  international coordination concerning the termination of their use.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;... but overall states in the same document that only SI units should be used, the same units for all members. Nevertheless the termination dates for alternative units have not been specified:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is intended that the use of the non-SI alternative units [...]&#xA;  will eventually be discontinued in accordance with individual unit&#xA;  termination dates established by the Council. Termination dates, when&#xA;  established, will be given in Chapter 4.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Case of vertical measurements / altitude&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical measurement in meters may be the more complex due to the existence of flight levels in feet, with the full system of vertical separation based on FL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;This topic was discussed in &lt;a href=&quot;https://aviation.stackexchange.com/questions/1387/using-feet-vs-meters-for-altitude&quot;&gt;Using feet vs meters for altitude?&lt;/a&gt;. The current question is &lt;strong&gt;not a duplicate&lt;/strong&gt; of the latter.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Other non-SI units&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other non-SI measurements seem more easy to remove:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Horizontal distances in feet and nautical miles may be expressed in meters, as already done for runway lengths. It is not as important as it was to mentally translate a latitude offset in NM.&lt;/li&gt;&#xA;&lt;li&gt;Atmospheric pressure expressed in Hg column height may be expressed in Pascal. Many pressure instruments can be already calibrated both in inHg and hPa.&lt;/li&gt;&#xA;&lt;li&gt;Speeds expressed in knots (sometime in statute miles per hour) may be expressed in km/h.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eXAvh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it be useful (and safer) in the long term if we could remove most of the imperial units from new aircraft instrumentation, procedures, ATC, documentation and maps (at least for anything other than altitudes)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just asking what is the current view from the air transport community itself.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-04-17T04:05:16.457" Title="Still using knots, nautical miles, inches of Hg. Is that impossible to switch to SI units?" Tags="&lt;measurement&gt;&lt;gauge&gt;&lt;units&gt;" AnswerCount="1" CommentCount="10" ClosedDate="2015-02-10T21:55:39.527" ContentLicense="CC BY-SA 3.0" />
  <row Id="12601" PostTypeId="2" ParentId="12599" CreationDate="2015-02-10T20:13:42.950" Score="2" Body="&lt;p&gt;The difference is just because there are often disputed methods on which technique is best. To be brutally honest, many accidents are so severe and can't really be analysed, so this is still a point of contention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would hypothesize that the UK version is safer as the hand position protects the skull and face from direct impact with the seat in front; instead colliding with the inside forearm. This will naturally reduce impulse (strengthy plastic vs. fleshy skin) and should thus reduce injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept of holding ankles stems from the position your body is put in when holding your ankles. Any kind of &quot;holding&quot; is fine, touching on top or sides. It puts your body into a position that ducks your head and should (because of close seat proximity) rest your head against the seat infront anyway. &lt;/p&gt;&#xA;" OwnerUserId="7280" LastActivityDate="2015-02-10T20:13:42.950" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12602" PostTypeId="2" ParentId="12580" CreationDate="2015-02-10T20:36:52.467" Score="2" Body="&lt;p&gt;Natural stability would be highest on the list for me. Look at free flying model airplanes for inspiration. They have their own characteristics:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Very low wing loading for minimum sink speed&lt;/li&gt;&#xA;&lt;li&gt;High natural stability, and consequently a very narrow speed range&lt;/li&gt;&#xA;&lt;li&gt;High aspect ratio wing, thin airfoil with high camber&lt;/li&gt;&#xA;&lt;li&gt;Extremely short fuselage ahead of the wing (no payload to carry)&lt;/li&gt;&#xA;&lt;li&gt;Extreme fuselage length aft of the wing which provides ample aerodynamic damping&lt;/li&gt;&#xA;&lt;li&gt;Strong dihedral of the outer wing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This in combination means that your control software can be very simple. Relaxed stability will require many sensors and built-in redundancy, and the more parts you need to add, the more possibilities of failures you will end up with. In contrast to that, the laws of physics never fail, use them to your advantage. See below for an example which I copied from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Free_flight_(model_aircraft)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia page&lt;/a&gt; on free flight models:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/E87Gu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airfols, c.g. location and all other details I recommend to look at &lt;a href=&quot;http://freeflight.org/community/links.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;several free plans&lt;/a&gt; until you see a common pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the type of fuel: Depends how noisy and messy you tolerate the engine to be; some people will only fly electric while others are happy with two-stroke engines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-10T20:45:56.360" LastActivityDate="2015-02-10T20:45:56.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12603" PostTypeId="2" ParentId="12600" CreationDate="2015-02-10T21:01:46.350" Score="2" Body="&lt;p&gt;For me metric or imperial is not the question, from my perspective the key is standardization. Having 2 different unit systems has only got drawbacks:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Customers: many airline's customers are living in a metric system, and they do not know what's is a mile or a feet. Is a matter of making flights more comfortable.&lt;/li&gt;&#xA;&lt;li&gt;Cost reduction: units transformation is finally a cost. Engineer at manufacturers and airlines need to spend some time using a calculator to understand what is meant by other unit system. Maybe is only 30 minutes per month, but if we are talking about 2000 people, we are reaching a cost that is not adding value of 1000h per month. Finally this cost is somehow appearing in our airplane tickets. &lt;/li&gt;&#xA;&lt;li&gt;Reduce human factor: we all are humans and exposed to errors. The less opportunity we have to make an error the best. Already there had been an issue with satellites with &lt;a href=&quot;http://articles.latimes.com/1999/oct/01/news/mn-17288&quot; rel=&quot;nofollow&quot;&gt;unit conversion&lt;/a&gt;. Reducing this difficulty is finally improving the safety of the air transport.&lt;/li&gt;&#xA;&lt;li&gt;Increase competence in the sector: suppliers from, let's say, metric system have an slight competitive disadvantage when competing for a contract with imperial units. The more competition in airline services, airplane manufacturers suppliers, handling services the lower the price of our tickets. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Having 2 standards is a cost that is not producing any value and is actually a sector issue, moreover, a society issue. From my point of view the industry should try to move to a single standard. Metric or Imperial, I don't mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next discussion will be which side of the road we should drive...&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2015-02-11T06:32:25.773" LastActivityDate="2015-02-11T06:32:25.773" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12605" PostTypeId="2" ParentId="391" CreationDate="2015-02-10T22:28:33.817" Score="4" Body="&lt;p&gt;It really depends on the jet and what type of fire it is and where it's located.  It is my understanding you are not necessarily RAM DUMPing (depressurizing) to starve the fire, but remove the smoke and fumes from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In our checklist for an engine fire, you just want to get the engine shutdown as fast as possible to prevent burning through hydraulic lines, fuel lines, etc; your next step is to land the jet.  It makes no mention of depressurizing the jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for an electrical fire the first steps are to gangload your regulator (100% O2/EMERGENCY) and RAM DUMP the cockpit and then start getting the battery, generators, and each individual component shut off to isolate the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, standard pilot answer, IT DEPENDS... It depends on what the checklist calls for your specific jet and in your specific EP.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-10T22:28:33.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12606" PostTypeId="2" ParentId="12581" CreationDate="2015-02-11T00:05:30.743" Score="4" Body="&lt;p&gt;The general rules for this are in &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/AIR/index.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Joint Order 7400.2K&lt;/a&gt;, &lt;em&gt;Procedures for Handling Airspace Matters&lt;/em&gt;. &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/AIR/air2001.html#air2001.html.1&quot; rel=&quot;nofollow&quot;&gt;Chapter 20&lt;/a&gt; describes when and how air routes are defined and designated, although it doesn't go into much detail about some things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the instructions on when to create a route are fairly general:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;20-1-3. WHEN TO DESIGNATE AIR NAVIGATION ROUTES&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;ATS routes should be designated to serve en route operations when:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. The route is predicated upon NAVAIDs that are suitable for&#xA;  inclusion in the system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. The benefits of the designation should outweigh any adverse effects&#xA;  to other airspace users, and:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. The route is a normal extension of an existing airway; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. Users will benefit from charted information pertaining to navigational guidance, minimum en route altitudes, and changeover&#xA;  points.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Similarly, although there are some clear rules for NAVAID spacing, it doesn't tell you why a route would follow certain ones and not others:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;20-3-1. NAVAID SPACING&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. VOR Federal airways are based on NAVAIDs which normally are spaced&#xA;  no farther apart than 80 NM. They may be based on more widely spaced&#xA;  NAVAIDs if a usable signal can be provided and frequency protection&#xA;  afforded for the distance required (see Order 9840.1, U.S. National&#xA;  Aviation Handbook for the VOR/DME/TACAN Systems).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The naming convention is in 20-1-5:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;20-1-5. ROUTE IDENTIFICATION&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Dual designation of ATS routes must be avoided. All alpha-numeric ATS&#xA;  route identifications must be assigned by Airspace Regulations and ATC&#xA;  Procedures Group as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Identify ATS routes based on L/MF NAVAIDs by color names (e.g.&#xA;  Amber, Blue, Green, and Red) followed by a number designation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. Designate those routes extending east and west as Green or Red.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2.  Designate those extending north and south as Amber or Blue.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. Identify ATS routes based on VOR NAVAIDs as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. Route lettering must be as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The letter “V&quot; will prefix low altitude ATS routes below FL 180.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The letter “J&quot; will prefix high altitude ATS routes at FL 180&#xA;  through FL 450.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. Route numbering must be as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Assign even numbers for those ATS routes extending east and west.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Assign odd numbers for those ATS routes extending north and south.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Identify advanced RNAV ATS routes as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1. The letter “T&quot; will prefix low altitude RNAV ATS routes below FL 180, and the letter “Q&quot; for RNAV routes FL 180 and above.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. Route numbering must follow the guidelines detailed in paragraph 20-1-5.b.1.(a) and b.2.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Route segments must be listed from West to East for even numbered&#xA;  ATS routes, or South to North for odd numbered routes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many airways don't follow that numbering convention exactly, at least on certain segments. For example, V67 is more or less &lt;a href=&quot;http://skyvector.com/?ll=35.729122978020584,-86.83575439788979&amp;amp;chart=302&amp;amp;zoom=3&quot; rel=&quot;nofollow&quot;&gt;east-west between the GHM and SYI NAVAIDs&lt;/a&gt; although overall it's mostly north-south (from ENL to GQO). I assume that as the number of routes increased, they became longer and less consistent, possibly to avoid creating too many total routes: it looks like the lower-numbered routes are often more 'correct' than higher-numbered ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But just like with a road, even if it's clear why the road exists (&lt;em&gt;I can see that people want to drive from A to B&lt;/em&gt;) it may not be clear why it follows the exact route it does (&lt;em&gt;why does the road go north of that hill and not south of it?&lt;/em&gt;). All those 'small' decisions were made by the person who designed the route and there's probably no way to know them all.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-11T00:05:30.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12607" PostTypeId="2" ParentId="3300" CreationDate="2015-02-11T00:06:24.487" Score="0" Body="&lt;p&gt;&lt;strong&gt;Noise&lt;/strong&gt; and &lt;strong&gt;Safety&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noise - If you live in a big city, take a look out nearest window at the traffic snarl below. Now imagine all those cars (or at least half) replaced by flying human-sized quad-copters. To scale up, those quads will need piston engines (or expensive turbines) and large rotors, and if successful there will be literally millions of them in the sky above any medium to large city. It would be a constant, deafening drone which would significantly reduce the livability of the city.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Black Knight Transformer mentioned by @menjaraz is very, very noisy, as are conventional helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safety - Unless you're a qualified pilot, you can't manually operate an aircraft. This means they'll need to be able to take off, fly and land fully automated to their destination, navigate along the way, communicate with and avoid other traffic and have some kind of interaction with ATC, all done for you by computer(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both these problems are surmountable, but will require significant R&amp;amp;D, which means investing big dollars in a shakey economy. And who's going to buy all these multi-million dollar machines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;: The limitations on human scale quad copters are primarily economic, regulatory and environmental, but those are significant limitations.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-02-11T00:06:24.487" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12608" PostTypeId="2" ParentId="12375" CreationDate="2015-02-11T01:29:06.947" Score="3" Body="&lt;p&gt;The question (as titled) may be impossible to answer, but here goes...&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;The short answer&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This may be the most intuitive answer of all: Look at a visual map of planes currently in the air.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Theory: What does the question mean?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Assuming there exists only one airway between each destination pair, the busiest airway, by definition, would be the one that connects the busiest destination pair (airports/metropolitan areas with the most departures/arivals).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since in reality there is an &lt;em&gt;arbitrary&lt;/em&gt; number of airways between two destinations, the question doesn't really make sense. Do we count two airways the same if they are parallel and 20 miles apart? Why or why not? It is simply an economic question at this point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;busiest airway&lt;/em&gt; could be one in the 'middle of nowhere', but since it is the only one in its area it gets all the traffic.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Practice: What are the busiest airways between two destinations?&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://flightaware.com/resources/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flightaware&lt;/a&gt; will show you &lt;em&gt;recently used IFR routes&lt;/em&gt;. &lt;a href=&quot;https://flightaware.com/analysis/route.rvt?origin=ZSE&amp;amp;destination=ZLA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is an example for traffic going from Seattle to Los Angeles&lt;/a&gt;. This gives a summary of how many times a particular route was used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To find the busiest airways between areas of the country, simply count the number of times each airway was used.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Traffic Breakdown by Center&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a breakdown of aircraft volume transiting between and within the 22 area control centers in the United States?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can obtain custom traffic reports through the FAA's &lt;a href=&quot;http://www.faa.gov/news/media_resources/atadsguide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Traffic Activity System (ATADS)&lt;/a&gt;, specifically the &lt;a href=&quot;http://aspm.faa.gov/opsnet/sys/Center.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Center Aircraft Handled&lt;/a&gt; page. There are options to break down traffic by a number of parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I would suggest the following settings to get started:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;strong&gt;Output&lt;/strong&gt;, select:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Standard Report&lt;/li&gt;&#xA;&lt;li&gt;Show Aircraft Handled (provides totals broken down by operation type)&lt;/li&gt;&#xA;&lt;li&gt;Show VFR Advisories (for fun)&lt;/li&gt;&#xA;&lt;li&gt;Show Domestic (provides a breakdown of domestic departures and overflights)&lt;/li&gt;&#xA;&lt;li&gt;Show Oceanic (provides a breakdown of oceanic departures and overflights)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mIY3j.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It sounds like you don't care about the &lt;strong&gt;Dates&lt;/strong&gt; as much; I have selected 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/J441C.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;strong&gt;Facilities&lt;/strong&gt;, select all of the Centers. You have to individually check each one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6iPrk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under &lt;strong&gt;Groupings&lt;/strong&gt;, select Facility only. If you add others there will simply be extra summary rows in the output.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TRE6X.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Click run and enjoy the output. Then try different settings if you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you can branch out into Terminal operations as well.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-02-12T07:12:44.447" LastActivityDate="2015-02-12T07:12:44.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12609" PostTypeId="1" AcceptedAnswerId="12617" CreationDate="2015-02-11T02:05:06.793" Score="8" ViewCount="2091" Body="&lt;p&gt;I am asking this seemingly odd question, as we'll have to transport some medicine in our luggage and it's supposed to be stored at temperatures between &lt;code&gt;-8C&lt;/code&gt; and &lt;code&gt;+2C&lt;/code&gt;. I'm not sure, if airport security will allow this to pass if this is in a cooling box as hand-luggage, although, in my opinion there shouldn't be a problem, as the ampules are &lt;code&gt;4 x 1 ml&lt;/code&gt; and I have a prescription (however, the cooling box will probably be treated as partially liquid containing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your advice will be much appreciated!&lt;/p&gt;&#xA;" OwnerUserId="7282" LastEditorUserId="62" LastEditDate="2015-02-11T16:18:37.680" LastActivityDate="2015-02-11T19:37:01.317" Title="What is the average temperature in the luggage hold of a passenger plane?" Tags="&lt;temperature&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2015-02-11T19:58:42.223" ContentLicense="CC BY-SA 3.0" />
  <row Id="12610" PostTypeId="1" AcceptedAnswerId="12615" CreationDate="2015-02-11T02:17:46.393" Score="12" ViewCount="2043" Body="&lt;p&gt;To my knowledge the only aircraft featuring a &lt;a href=&quot;http://en.wikipedia.org/wiki/Crescent_wing&quot; rel=&quot;noreferrer&quot;&gt;crescent wing&lt;/a&gt; that was built in numbers was the Handley Page Victor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that a crescent wing offers the possibility of a high subsonic/transonic aircraft with a thick wing root but not too much drag at the root. It seems that a crescent wing would work well at airliner speeds.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why there were not more crescent wing aircraft been built?&lt;/li&gt;&#xA;&lt;li&gt;Why are they not used on airliners?&lt;/li&gt;&#xA;&lt;li&gt;Is there any application where a crescent wing would be an ideal or even a good solution?  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="65" LastEditDate="2015-02-11T16:26:45.773" LastActivityDate="2017-12-31T15:25:58.720" Title="Is there any application where the crescent wing would be the best wing planform?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12612" PostTypeId="2" ParentId="12610" CreationDate="2015-02-11T05:23:21.773" Score="7" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Avro_Vulcan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Avro Vulcan B2&lt;/a&gt; also featured higher sweep angles at the wing root.  In modern aircraft, while not as extreme as the Victor, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 737&lt;/a&gt; also incorporates a slightly higher sweep angle at the wing root than at the tip.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9tz8Z.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the reasons the Victor engineers chose this was that the more extreme sweep angle enabled the design team to house engines and landing gear near the wing root since they could make that section fatter without incurring additional drag.  &lt;a href=&quot;https://youtu.be/EV6yl_hAONE&quot; rel=&quot;nofollow noreferrer&quot;&gt;This video&lt;/a&gt; (&quot;The Crescent Wing&quot; - Handley Page Builds the Victor V Bomber) explains some of the science behind it, plus a good explanation of stall conditions as they develop based on different wing geometries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most probable cause for non-development in this arena is because it's more expensive to fly faster.  As noted in &lt;a href=&quot;https://aviation.stackexchange.com/q/11936/6919&quot;&gt;this question&lt;/a&gt;, Mach 0.8-0.85 seems to be the sweet spot.  And on that subject, &lt;a href=&quot;https://aviation.stackexchange.com/a/11948/6919&quot;&gt;Peter's answer&lt;/a&gt; has a good idea why.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="14897" LastEditDate="2017-12-31T15:25:58.720" LastActivityDate="2017-12-31T15:25:58.720" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12615" PostTypeId="2" ParentId="12610" CreationDate="2015-02-11T16:22:29.140" Score="15" Body="&lt;p&gt;You are right, it helps to de-sweep the outer wing. The main advantages are (read &lt;a href=&quot;https://www.flightglobal.com/pdfarchive/view/1959/1959%20-%202812.html&quot; rel=&quot;noreferrer&quot;&gt;this Flight article from 1965 here&lt;/a&gt; for a much more detailed explanation):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An identical critical Mach number over the whole span as sweep is reduced together with relative thickness.&lt;/li&gt;&#xA;&lt;li&gt;A smooth cross-section distribution in the direction of flow which helps to reduce transsonic drag.&lt;/li&gt;&#xA;&lt;li&gt;A tendency to pitch up in ground effect such that the wing will essentially land itself, especially when combined with a T-tail.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, as long as wings are made of aluminum, the manufacturing effort is significantly higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic problem is the needed two-dimensional bending of the skin panels. Using a straight spar line and a straight leading edge requires bending only in one dimension, but when sweep changes, the skin panels would need to stretch in some corners while being bent. This requires much more expensive tooling, or a break in the structure which increases structural mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;one composite wing&lt;/a&gt; I know of has a straight leading edge, even though the aircraft would have benefited from de-sweeping. Both the &lt;a href=&quot;https://schwertasblog.wordpress.com/2011/07/12/die-entnationalisierung-des-europaischen-kampfflugzeugbaus/&quot; rel=&quot;noreferrer&quot;&gt;TKF-90&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rockwell-MBB_X-31&quot; rel=&quot;noreferrer&quot;&gt;X-31&lt;/a&gt;, which were designed by the same people before, had reduced sweep on the outer wing, and for good reason. When the multinational project started and they talked to the BAe engineers, the British side insisted on a straight leading edge for easier manufacture, ignorant of the fact that using composites made their point moot. Yes, that was practically the same company that had built the Victor before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another disadvantage is the fact that any sweep change will convert bending moment into torsion. Normally, this reduces the incidence of the outer wing when a swept-back wing is bending under lift loads. De-sweeping the outer wing will introduce an uptwisting torsion which can cancel the torsion from sweep-back, and Handley Page claimed that the Victor wing was close to &lt;a href=&quot;https://www.revolvy.com/topic/Short%20SB.4&amp;amp;item_type=topic&quot; rel=&quot;noreferrer&quot;&gt;aero-isoclinic&lt;/a&gt;. However, this reduces flutter damping, resulting in a &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/arc/rm/2869.pdf&quot; rel=&quot;noreferrer&quot;&gt;lower wing flutter speed (PDF!)&lt;/a&gt;. If the wing's aspect ratio is low, this is manageable, but with higher aspect ratios the wing needs to be stiffened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To answer your question directly:&lt;/strong&gt; In the majority of cases it is aerodynamically advantageous to vary sweep with relative thickness, but it is not structurally and economically efficient. In the delta wings of combat aircraft which need to operate over a wide range of angles of attack, de-sweeping the outer wing produces indeed the best wing planform, even when economics is included.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-12-31T13:24:44.537" LastActivityDate="2017-12-31T13:24:44.537" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12617" PostTypeId="2" ParentId="12609" CreationDate="2015-02-11T19:37:01.317" Score="6" Body="&lt;p&gt;According to an A320 pilot quoted in &lt;a href=&quot;https://travel.stackexchange.com/questions/22604/will-my-checked-luggage-freeze-in-the-airplane/22609#22609&quot;&gt;this question&lt;/a&gt; on travel.SE (and see &lt;a href=&quot;https://travel.stackexchange.com/questions/39113/what-is-the-average-max-temperature-of-an-airplane-cargo-hold&quot;&gt;this one&lt;/a&gt; too), the temperature can be 7C at the low end but potentially above 18C if animals are being transported. Therefore, if you want to transport something in the hold that needs to be kept at a specific temperature range you would need to check with the airline about how to do that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2015-02-11T19:37:01.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12618" PostTypeId="1" AcceptedAnswerId="12623" CreationDate="2015-02-11T19:41:30.330" Score="4" ViewCount="224" Body="&lt;p&gt;Is this possible for some airports to perform full &lt;a href=&quot;http://www.eurocontrol.int/articles/continuous-descent-operations-cdo&quot; rel=&quot;nofollow noreferrer&quot;&gt;continuous descent operations&lt;/a&gt; (CDO), gliding at idle thrust from top of descent to glideslope interception.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kr3fc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;https://lubomitev.wordpress.com/2011/01/02/flying-green-air-transport-today/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lubo Mitev's Blog&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LAX and UK airports seem to allow some CDO, maybe not from ToD.&#xA;What is the current status of such experimentations?&#xA;Is this something that could/should be extended to a lot of (or all) commercial planes?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-02-11T20:32:42.373" Title="Is it currently feasible to glide airliners from cruise level to ILS glideslope (CDO)?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;approach&gt;&lt;descent&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12619" PostTypeId="1" AcceptedAnswerId="12624" CreationDate="2015-02-11T19:58:32.443" Score="26" ViewCount="9734" Body="&lt;ul&gt;&#xA;&lt;li&gt;Shouldn't aircraft be able to withstand winds of up to 100 mph? When flying the wind is at a much higher speed than that.&lt;/li&gt;&#xA;&lt;li&gt;Shouldn't they be able to take-off through fog using instruments alone?&lt;/li&gt;&#xA;&lt;li&gt;Shouldn't they be able to take-off on a slippery runway, since the wheels are not powered.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="914" LastEditorUserId="62" LastEditDate="2015-02-11T21:56:54.900" LastActivityDate="2017-02-14T11:43:34.337" Title="Why do airports have to close in bad weather?" Tags="&lt;airport&gt;&lt;weather&gt;&lt;aircraft-limitations&gt;" AnswerCount="9" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12620" PostTypeId="2" ParentId="12619" CreationDate="2015-02-11T20:09:45.513" Score="8" Body="&lt;p&gt;In order:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the wind were exactly aligned with the runway this might be theoretically possible.  Maybe.  But, the wind never directly lines up with the runway, and a 100mph crosswind would blow the airplane right off the runway before it ever got off the ground, causing it to crash.&lt;/li&gt;&#xA;&lt;li&gt;They can, though it's better if you can at least see the runway lights.  What is actually impossible is taxiing, there's no system that allows you to follow taxiways to the terminals with no visibility.&lt;/li&gt;&#xA;&lt;li&gt;Again, yes, they can use the runway so they can take off.  But, when they land, they do use their brakes to stop.  If their tires get no grip, the planes would generally slide off the runway (an no, engine braking is not powerful enough to stop a plane on their own.)  So having no traction on the runway may not stop you from taking off, but it will stop you from landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These are some of several reasons weather can shut down an airport, though there are several more.  You might considering asking about other conditions in separate questions though.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-02-11T20:09:45.513" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12621" PostTypeId="2" ParentId="12619" CreationDate="2015-02-11T20:10:39.280" Score="11" Body="&lt;p&gt;The wind should be coming from the right direction and be reasonably steady. Gusting crosswind is a very dangerous thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also it's not just the planes that need to be out in the cold wind but also the ground crew, if you force them to work in such condition you will get unions on your doorstep, &lt;em&gt;unions&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On takeoff you need to maintain the center line, if you deviate a bit the plane will plough into the grass next to it and you will not be flying today.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-11T20:10:39.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12622" PostTypeId="2" ParentId="12619" CreationDate="2015-02-11T20:18:36.950" Score="28" Body="&lt;p&gt;&lt;strong&gt;Wind&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with wind is that it can be from any direction, not necessarily the direction of the runway. When the wind is coming from the side instead of straight ahead, it is called a crosswind. This means that landing aircraft have to point into the wind to remain lined up with the runway. The slower they are flying, the further to the side they must point the nose. &lt;a href=&quot;https://aviation.stackexchange.com/questions/1285/is-the-main-landing-gear-of-a-large-airplane-designed-for-sideways-crabbed-tou&quot;&gt;Airliners are designed to land in these conditions&lt;/a&gt;, but it requires more skill to do it well. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9789/understanding-cross-wind-correction-controls&quot;&gt;The control inputs required&lt;/a&gt; to compensate for a crosswind affect aircraft on takeoff as well, as then must work harder to stay lined up with the runway and stay level through lifting off. High winds tend to come along with gusts, which makes it even harder to control an aircraft. Aircraft during flight are flying faster, so changes in wind are less problematic. Once they are flying slower, the wind is much larger compared to the aircraft's speed, and control is much more critical during landing. Aircraft have &lt;a href=&quot;https://aviation.stackexchange.com/questions/12518/what-determines-crosswind-limits&quot;&gt;crosswind limits&lt;/a&gt;, and even below those limits, aircraft may need to go around from a landing attempt, which introduces delays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue is wind shear, which is when the direction and/or speed of the wind quickly changes. A change of 40 knots at higher speeds is turbulence. During landing or takeoff, it can cause the aircraft to stall and crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Visibility&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft can certainly use &lt;a href=&quot;https://aviation.stackexchange.com/questions/2620/how-does-ils-instrument-landing-system-work&quot;&gt;systems like ILS&lt;/a&gt; that allow them to &lt;a href=&quot;https://aviation.stackexchange.com/questions/2866/on-modern-commercial-airliners-how-much-of-the-flight-could-be-fully-taken-care&quot;&gt;take off or land in low visibility&lt;/a&gt;. However, there are many limitations with these systems. The crew must be trained to use them, the aircraft must be equipped to use them, and the airport must be equipped with them. However, when the pilots are relying on instruments, they no longer are able to see hazards like usual. Because of this, separation requirements are inreased in these conditions, which means an airport can't handle as much traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Water&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's true that aircraft wheels are not directly powered. However, traction is still very important during braking, since aircraft &lt;a href=&quot;http://avherald.com/h?article=4426fd5b/0000&quot; rel=&quot;nofollow noreferrer&quot;&gt;can hydroplane just like a car can&lt;/a&gt;. This means aircraft need more distance to stop, and can slide off the runway if they lose traction. Frozen water in the form of ice or snow makes a plane even more difficult to steer or stop.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Combine all of the above (a typical storm that would cause delays at an airport), and you can see why airports delay flights or close when conditions get worse.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-02-11T21:26:20.703" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12623" PostTypeId="2" ParentId="12618" CreationDate="2015-02-11T20:32:42.373" Score="8" Body="&lt;p&gt;Yes it is feasible, in fact it is no problem at all for an aircraft to perform a Continuous Descent Approach (CDA). The difficulty is that Air Traffic Control (ATC) can not predict accurately how the progress of the aircraft will be during the CDA, so they will need to add extra spacing from other aircraft to ensure safe separation. This reduces the capacity of the airport. Therefore CDA's are only used when there is no need for high runway throughput. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Amsterdam airport uses CDA's from Top of Descent during the night hours and in the early morning. Around 6.30 AM local time they can no longer offer CDA's without risking separation conflicts with other aircraft as traffic start to increase rapidly around that time. They will need to vector and put aircraft on doglegs to ensure separation minima are honoured.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-02-11T20:32:42.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12624" PostTypeId="2" ParentId="12619" CreationDate="2015-02-11T21:17:04.307" Score="19" Body="&lt;p&gt;Adding to what the others have mentioned, bad weather is often a combination of low visibility, low ceilings, precipitation, high winds and lightning.&lt;/p&gt;&#xA;&lt;h3&gt;Visibility and ceilings&lt;/h3&gt;&#xA;&lt;p&gt;As mentioned in @fooot's answer, ILS is available to land when in these conditions.  Every airliner and crew (and just about every airport they'd go into) is trained and equipped for ILS operations.  A standard ILS approach is good in weather down to 200 ft ceilings and 1800 or 2400 ft visibility along the runway (RVR).  Further airplane and airport equipment and aircrew training can allow ILS category II and III operations, which reduce these numbers (cat II is 100 ft vertical visibility and RVR 1200, cat III goes down to essentially no visibility).&lt;/p&gt;&#xA;&lt;p&gt;To takeoff, a 2 engined airliner needs 5000 ft RVR (1 mile vis) normally.  Airport lighting and airline opspecs can reduce this as low as RVR 300.&lt;/p&gt;&#xA;&lt;h3&gt;Wind&lt;/h3&gt;&#xA;&lt;p&gt;High winds are fine, but can make the landing more challenging.  When the winds are strong and particularly gusty, a lower flap setting can be used to land and a faster approach speed flown.  This will, however, necessitate a long landing rollout.  Exceptional crosswinds can also present problems aligning the aircraft with the runway, and if you can't line up, you can't land (note that some larger airplanes can land in a crab and do not need to align with the runway until the main gear are on the ground).&lt;/p&gt;&#xA;&lt;h3&gt;Runway condition&lt;/h3&gt;&#xA;&lt;p&gt;You mention the wheels are not powered, and this is true.  However, the friction between the runway and the contact patch on the tire is the only thing keeping the airplane on the runway in strong crosswinds, so you need friction to land (or takeoff) if there is a crosswind component.&lt;/p&gt;&#xA;&lt;p&gt;Anything reducing friction is problematic (rain, snow, ice, rubber, etc),  With high water you risk hydroplaning and this (or snow/ice) can lead to departures from the runway sides or an overrun if braking action is insufficient due to lack of friction.  Ice needs to be chemically treated and snow must either be treated or plowed at regular intervals (while it is snowing). Ground handlers at the airport must also have deice fluid and the equipment to apply it to aircraft available for operations in snow.&lt;/p&gt;&#xA;&lt;h3&gt;Lightning&lt;/h3&gt;&#xA;&lt;p&gt;When lightning is in the vicinity, ground crews go inside as it is a deadly hazard to be on the ramp in those conditions.&lt;/p&gt;&#xA;&lt;h3&gt;Summary&lt;/h3&gt;&#xA;&lt;p&gt;All of these things contribute to lowered arrival rates into the airport and as conditions deteriorate you reach a point where you are spending more time dealing with keeping the airport open than departing airplanes and it makes sense to close the airport temporarily.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-29T21:07:04.517" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12625" PostTypeId="2" ParentId="12619" CreationDate="2015-02-12T06:49:54.097" Score="5" Body="&lt;h2&gt;Wind&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Shouldn't aircraft be able to withstand winds of up to 100 mph?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Can the airframe withstand it? Sure. They deal with twice that in the jet stream almost daily. Can they land or take off in it? Not so much, especially if the wind is not straight down the runway (which it almost never is.) Every aircraft has a maximum crosswind component in which it can complete a safe takeoff or landing roll. I'm not aware of any of them near the 100 mph figure. What happens when you try to take off with a crosswind component that is too high? Well, possibly something like &lt;a href=&quot;http://en.wikipedia.org/wiki/Continental_Airlines_Flight_1404&quot; rel=&quot;nofollow&quot;&gt;Continental Airlines Flight 1404&lt;/a&gt;, which got blown off the side of the runway on takeoff in Denver after it had already accelerated above 100 knots. Everyone survived, but the Captain as well as another person sustain critical injuries and the aircraft was destroyed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The worst part about winds from storms, though, is that they tend to be very gusty with rapid changes in both magnitude and direction. Say you're flying a final approach and you suddenly encounter a 50 knot tail wind. Your wings just stalled and, if you're low enough and/or the gust lasts long enough, you just crashed short of the runway. Also, sudden changes in crosswinds can cause runway excursions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thunderstorms are also capable of producing a nasty type of sudden downdraft called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Microburst&quot; rel=&quot;nofollow&quot;&gt;microburst&lt;/a&gt;. These are particularly nasty to encounter at low altitude. As you approach a microburst, it causes you to have a sudden strong headwind (and, thus, higher airspeed,) which suddenly increases the lift of the wings, while also slowing down the ground speed of the aircraft. Pilots may naturally compensate for the increased airspeed by reducing power. This then becomes a huge problem seconds later when that headwind vanishes and the wind is instead pushing the aircraft straight downward, causing it to lose altitude quickly. To make a bad problem worse, as the aircraft flies out of the microburst, it now has a sudden tailwind, which quickly decreases the airspeed, causing the wings to produce significantly less lift and perhaps even stall. Encountering such a microburst on short final to DFW near a thunderstorm caused the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_191&quot; rel=&quot;nofollow&quot;&gt;Delta Air Lines Flight 191&lt;/a&gt; in 1985, one of the most deadly aviation accidents in U.S. history.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Visibility&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Shouldn't they be able to take off through fog using instruments alone?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sure. They do it all the time (in the case of airliners, at least.) Visual flight rules are not allowed in fog, but all airliner flights use instrument flight rules anyway. Sometimes they execute visual approaches, but nearly every airport that handles airliners and all airliners and airline flight crews have the ability to perform an instrument landing. Many commercial airport runways (and most airliners) are equipped and certified for fully automated landings. Takeoff doesn't even need that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;General Aviation is another matter here, though. Pilots and/or aircraft not certified for instrument flight rules cannot operate in fog. While many GA pilots and aircraft are certified for IFR, many also aren't. Flights not using IFR must be operated under &lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/25/185/VFR%20Weather%20Minimums.pdf&quot; rel=&quot;nofollow&quot;&gt;Visual Meteorological Conditions&lt;/a&gt;, which generally require that aircraft can only land or take off when the cloud ceiling is more than 1,000 feet above the ground level and horizontal visibility is at least 3 statute miles (at least in the U.S.)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Traction&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Shouldn't they be able to take-off on a slippery runway, since the wheels are not powered?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not really, no. The big problem here is not the lack of ability to accelerate with the wheels, but rather the lack of directional control and the inability to brake. On both takeoff and landing, the aircraft relies on the contact of the landing gear with the pavement to maintain directional control. Also, traction is also obviously required to use the wheel brakes (which provide the primary stopping force on airliners.) Ice is particularly nasty about causing loss of directional control on the runway. For example, &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19951220-0&quot; rel=&quot;nofollow&quot;&gt;Tower Air Flight 41&lt;/a&gt;, a 747 departing JFK for Miami, lost directional control on takeoff due to ice, resulting in a runway excursion. There were no fatalities, unless you count the 747 itself, which was damaged beyond repair.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="1654" LastEditDate="2015-02-12T16:29:23.447" LastActivityDate="2015-02-12T16:29:23.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12626" PostTypeId="1" CreationDate="2015-02-12T07:52:13.473" Score="13" ViewCount="1370" Body="&lt;p&gt;Airports usually close or slow down activities in fog conditions, e.g. this seems to be a &lt;a href=&quot;https://www.business-standard.com/article/current-affairs/fog-hits-operations-at-delhi-airport-116010800907_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;significant problem in winter at Delhi airport&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large commercial aircraft would be able to land with no visibility (more accurately with no &lt;a href=&quot;https://www.skybrary.aero/index.php/Decision_Altitude/Height_(DA/DH)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Decision Altitude/Height&lt;/a&gt;). However, if using the ground ILS, the runway must offer a &lt;a href=&quot;https://aviation.stackexchange.com/a/32361/3201&quot;&gt;Category IIIc landing system&lt;/a&gt;. While Cat IIIa and Cat IIIb are common at large airports, there are no Cat IIIc runways in the world of commercial aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is landed aircraft wouldn't be able to safely leave the runway and taxi to the gate because taxiways are not equipped with features appropriate to no-visibility conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand driverless cars now are experimented on public roads without specific equipment, &lt;a href=&quot;https://www.asme.org/topics-resources/content/system-helps-selfdriving-cars-see-fog&quot; rel=&quot;nofollow noreferrer&quot;&gt;including in fog&lt;/a&gt;, and driverless vehicles push back aircraft prior to taxiing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2qx2p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2qx2p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Driverless pushback at Heathrow (&lt;a href=&quot;https://www.youtube.com/watch?v=1TCUghnOw3A&quot; rel=&quot;nofollow noreferrer&quot;&gt;source Youtube&lt;/a&gt; and &lt;a href=&quot;https://www.mototok.com/tugs&quot; rel=&quot;nofollow noreferrer&quot;&gt;manufacturer site&lt;/a&gt;, can be autonomous with ground markings)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the long term airports with autonomous tugs on the whole taxi phase may be interesting as they allow savings by providing power supply while taxing, which in turn can decrease fuel needs and mechanical wear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a possibility such zero visibility landings could happen in the near future, because desirable for airlines and airports?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-18T17:40:23.887" LastActivityDate="2019-11-18T21:16:43.030" Title="Are zero visibility landings a possibility for the future of commercial aviation?" Tags="&lt;weather&gt;&lt;taxiing&gt;&lt;ils&gt;&lt;airport-design&gt;&lt;visibility&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="12627" PostTypeId="1" AcceptedAnswerId="12628" CreationDate="2015-02-12T08:13:46.953" Score="11" ViewCount="2203" Body="&lt;p&gt;We have seen that after an emergency landing when the airplane needs to be evacuated promptly, &lt;a href=&quot;http://en.wikipedia.org/wiki/Evacuation_slide&quot;&gt;evacuation slides&lt;/a&gt; get deployed immediately. I am not sure if normal air is being inflated in those slides or do they use some other gas in them?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="65" LastEditDate="2015-02-12T14:58:44.890" LastActivityDate="2015-02-12T14:58:44.890" Title="Which gas is used to fill the evacuation slides of modern aircraft?" Tags="&lt;emergency&gt;&lt;equipment&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12628" PostTypeId="2" ParentId="12627" CreationDate="2015-02-12T08:36:39.163" Score="14" Body="&lt;p&gt;They are filled with carbon dioxide, oxygen and nitrogen. See &lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-evacuation-slides-22196601/?no-ist&quot;&gt;here&lt;/a&gt; for reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the linked article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Slides inflate with an initial boost from a canister of compressed&#xA;  carbon dioxide and nitrogen. The canister provides only about&#xA;  one-third the volume needed to inflate the slides. The remaining&#xA;  volume is supplied by ambient air, channeled into the slides through&#xA;  aspirators.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When the inflation mechanism is triggered—by a lanyard pulled by the&#xA;  slide as it tumbles from its storage case—gas from the canister&#xA;  accelerates through the aspirators at high speed, creating a vacuum&#xA;  that sucks ambient air into the aspirators through louvers. When the&#xA;  slide is fully inflated, the louvers close.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-02-12T08:36:39.163" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12629" PostTypeId="2" ParentId="9642" CreationDate="2015-02-12T10:13:26.773" Score="0" Body="&lt;p&gt;The separation of 5nm (Surveillance system based) or 1000ft vertical is the minimum and safe separtaion between two aircraft in any configuration. Though it needs to be understood that at least one of these separation need to be maintained at all points of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is likelihood of breach of one kind of separation in near future as in the case of converging traffic at same level, Air Traffic Control has to initiate action well in advance to ensure that other kind of separation is established before the existing separation is breached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question of TCAS warning does not arise.When the process for established other mode of separation is to be initiated is the whole job of ATC.  That is what Air Traffic control is all about.  &lt;/p&gt;&#xA;" OwnerUserId="7300" LastEditorUserId="3386" LastEditDate="2015-02-12T10:17:27.040" LastActivityDate="2015-02-12T10:17:27.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12631" PostTypeId="2" ParentId="9137" CreationDate="2015-02-12T16:48:51.413" Score="11" Body="&lt;p&gt;Just look at the wing loading: The &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-25&quot; rel=&quot;nofollow noreferrer&quot;&gt;Su-25&lt;/a&gt; has between 585 kg/m² (regular Su-25) and 691 kg/m² (Su-25TK) when fully loaded, whereas the &lt;a href=&quot;http://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-10&lt;/a&gt; has a wing loading of 316 kg/m². This alone should explain why the Su-25 cannot climb as high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even when flying at minimum mass, the Su-25 has still 309 kg/m² (345 kg/m² for the Su-25TK), and the A-10 is almost a glider by comparison, having just 208 kg/m² at minimum mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since both are subsonic designs, they have a strict limit on maximum speed. With that, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9188/what-determines-the-maximum-altitude-a-plane-can-reach/9227#9227&quot;&gt;wing loading and the airfoil determine their ceiling&lt;/a&gt; if thrust is sufficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another limiting factor is the cockpit: Since the Su-25 was designed for ground attack, it has an unpressurized cockpit. This detail limits the certified envelope, even though a lightly loaded Su-25 can climb higher than 7000 m.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-10T09:41:35.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12632" PostTypeId="2" ParentId="12619" CreationDate="2015-02-12T17:05:50.560" Score="1" Body="&lt;p&gt;If you look at historical behavior, you'll find that airports in the 1970s and 1980s generally didn't close for bad weather. Stapleton Airport in Denver for example, never closed for weather a single time until a major blizzard in 1982.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the reason they do now is liability law. Though they could theoretically continue to operate in most bad weather with a 99% chance of safety, that 1% chance of having an accident and facing an expensive lawsuit from injured passengers or surviving families causes them to err on the side of caution.&lt;/p&gt;&#xA;" OwnerUserId="7303" LastActivityDate="2015-02-12T17:05:50.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12633" PostTypeId="2" ParentId="12619" CreationDate="2015-02-12T17:42:22.207" Score="2" Body="&lt;p&gt;If 100 miles an hour generates enough lift for the aircraft to fly, then a wind gusting 100 miles per hour might result in the aircraft taking off while the passengers are still climbing the steps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kites fly without any speed relative to the ground.  When the wind blows strong enough, so do aircraft.  In weather like this the aircraft are either secured to the ground with tie-downs or taken indoors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Not that tie-downs always work.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/4/3/0/0977034.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hLg3s.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7304" LastEditorUserId="65" LastEditDate="2015-02-12T18:48:44.863" LastActivityDate="2015-02-12T18:48:44.863" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12634" PostTypeId="1" AcceptedAnswerId="12637" CreationDate="2015-02-12T19:20:21.737" Score="46" ViewCount="49046" Body="&lt;p&gt;I started using X-Plane and am surprised at the easiness of flying (using a flight controller). Does this simulation software reflect how it is to fly (in any way) in reality?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From using the simulator, I understand that all I need to do is to switch the engines on, turn the brakes off and fly. Are there any additional things apart from a pre-flight checklist that an actual airline pilot has to do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, I understand that I haven't dove into the details of navigation in X-Plane as I am just wondering if the basics of the simulator software reflect real life conditions.&lt;/p&gt;&#xA;" OwnerUserId="2150" LastEditorUserId="258" LastEditDate="2015-02-12T21:14:26.403" LastActivityDate="2020-12-04T15:22:24.420" Title="How close is X-Plane experience to real flying?" Tags="&lt;flight-simulator&gt;&lt;pilot-technique&gt;" AnswerCount="9" CommentCount="8" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="12635" PostTypeId="2" ParentId="12634" CreationDate="2015-02-12T19:26:12.633" Score="4" Body="&lt;p&gt;Before flying the pilot needs to check the plane to make sure it doesn't have any damage and everything is in working order. Like control surfaces move the way you expect them to, all tires are inflated, the fuel isn't contaminated and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The the pilot needs to taxi from the parking spot to the runway. While making sure to not to bump into any other while talking to the tower. Then line up set flaps increase power and go.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-12T19:26:12.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12636" PostTypeId="2" ParentId="12634" CreationDate="2015-02-12T19:34:00.017" Score="15" Body="&lt;p&gt;X-Plane and other simulators can be set up to reflect the complexity of real-life aircraft systems, down to a certain level of detail, e.g. most serious flight-sim enthusiasts usually start their complex aircraft&lt;sup&gt;1&lt;/sup&gt; from what is called &quot;cold and dark&quot; configuration manually, rather than using a pre-defined shortcut to start up the engines. Some configuration options that would have no benefit in flight simulation are obviously omitted, such as temperature control of the cabin or pressure control of the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight dynamics are in most cases very close to the real aircraft, but the simulator will of course lack the actual feeling of movement, which can only be simulated in full-motion simulators to a certain degree. Since the systems are a calculation of the real thing, some phenomena such as ILS (Instrument Landing System) errors due to deflection are not simulated, but can be encountered in real life. The simulator can also be set to ignore weather, which is not an option in reality. Weather phenomena such as windshears and gusting winds may not be properly simulated throughout all simulators alike or require additional software to come close to realistic simulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless you are part of an flight-sim network such as &lt;a href=&quot;http://www.vatsim.net&quot; rel=&quot;noreferrer&quot;&gt;VATSIM&lt;/a&gt;, you will also lack the experience of ATC, which is an essential part of real aviation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related question:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/738/can-microsoft-flight-simulator-help-me-learn-to-fly-or-make-me-a-better-pilot?s=4|1.2055&quot;&gt;Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: The default aircraft in x-plane and MS Flight Simulator are not very complex and do not have the level of detail you would expect. This is why there are developpers publishing realistic aircraft addons for simulators.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-02-12T21:06:41.170" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12637" PostTypeId="2" ParentId="12634" CreationDate="2015-02-12T20:01:11.843" Score="42" Body="&lt;p&gt;X-Plane is a much truer simulation of flying than that flight game Microsoft used to make. In fact, when coupled with certified hardware and a CFI, X-Plane can power a sim that you can actually log FTD time in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you ask about airline flying for your comparison, there is a lot more to that than just the flying. An airline pilot is, with few exceptions, always operating under instrument flight rules (IFR). This means flying in the clouds with no reference to anything but instruments, weather as bad as a few hundred feet visibility and strong crosswinds for landing and takeoff are all part of normal ops. You are also operating under ATC, so radio ops are normal. The only comparable computer simulation of ATC to reality is VATSIM (as mentioned in comments), though it doesn't approach the level of busyness that you'll find in some airspace and airports (with the exception of some of their organized fly-ins).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A transport category jet is also a bit more complicated than &quot;turn the engines on, release the brakes and go&quot;. The only computer sims that capture the level of detail properly are ones like the &lt;a href=&quot;https://www.youtube.com/watch?v=FBylLsDIHog&quot; rel=&quot;noreferrer&quot;&gt;A-10 simulator by DCS&lt;/a&gt;. Before you can start the engines, you need to first power the aircraft and perform your receiving checklists, and if you are the first flight of the day, additional first-flight checks. These cover:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thorough pre-flight walkaround inspection&lt;/li&gt;&#xA;&lt;li&gt;Powering the airplane on batteries&lt;/li&gt;&#xA;&lt;li&gt;Transition to ground power (GPU) or start the APU for power&lt;/li&gt;&#xA;&lt;li&gt;Verifying the state of all systems&lt;/li&gt;&#xA;&lt;li&gt;Fire test&lt;/li&gt;&#xA;&lt;li&gt;Stall warning test&lt;/li&gt;&#xA;&lt;li&gt;Anti-ice system test&lt;/li&gt;&#xA;&lt;li&gt;Checking oxygen levels and masks&lt;/li&gt;&#xA;&lt;li&gt;Autopilot test&lt;/li&gt;&#xA;&lt;li&gt;Backup instrumentation checks&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Before pushback:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Verifying fuel load&lt;/li&gt;&#xA;&lt;li&gt;Get load information from flight attendant/gate agent/dispatch/ramp supervisor&lt;/li&gt;&#xA;&lt;li&gt;Calculate weight and balance, move passengers and/or bags if needed&lt;/li&gt;&#xA;&lt;li&gt;Get ATC clearance and program FMS&lt;/li&gt;&#xA;&lt;li&gt;Flight crew and cabin crew briefings&lt;/li&gt;&#xA;&lt;li&gt;Weather briefing &lt;/li&gt;&#xA;&lt;li&gt;Start APU and disconnect ground power and ground air conditioning&lt;/li&gt;&#xA;&lt;li&gt;Get clearance for pushback&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;During pushback:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Before engine start&quot; checklist&lt;/li&gt;&#xA;&lt;li&gt;Set bleeds / packs for engine start&lt;/li&gt;&#xA;&lt;li&gt;Communicate with ground crew for engine start&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now you can start an engine. Unlike a small airplane where you start the engine by turning a key in an ignition switch, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1959/how-are-turbine-engines-started&quot;&gt;in bigger airplanes its a series of knobs and buttons to press, sometimes dependent on certain events during the start&lt;/a&gt;. Engine parameters must also be monitored in case an abort becomes necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point you can get a taxi clearance and start moving toward the runway. You'll go through a couple more checklists, &quot;after start/taxi&quot; and &quot;before departure&quot;, to prepare the plane for taxi and takeoff. Once you are on the runway, with all checks completed, with more fuel than your minimum dispatch release, and an ATC clearance you may then release the brakes and go flying. One pilot will fly and the other will monitor instruments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much of the above is beyond the typical scope of X-Plane, though some can be addressed with specific aircraft add-ons, manuals and software like VATSIM. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-02-12T21:53:26.023" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12638" PostTypeId="1" AcceptedAnswerId="12639" CreationDate="2015-02-12T21:21:46.327" Score="7" ViewCount="1344" Body="&lt;p&gt;Sometimes the tower will advise aircraft that the &quot;departure cable&quot; is up or down. What are they referring to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airnav.com/airport/KPDX&quot;&gt;KPDX&lt;/a&gt; is one airport where this can be found.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-12T21:54:35.477" Title="What is the &quot;departure cable&quot; that tower mentions?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;&lt;arresting-gear&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12639" PostTypeId="2" ParentId="12638" CreationDate="2015-02-12T21:21:46.327" Score="17" Body="&lt;p&gt;The &quot;departure cable&quot; refers to an arresting gear cable on the departure end of the runway, similar to the one used for landing on aircraft carriers. Airports that often have fighter jet traffic may have an arresting system installed near each end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter jets tend to take off and land at higher speeds than other aircraft, and don't have the same braking power that other jets do. The speed brakes may not provide substantial drag, and the engines typically do not have reverse thrust capability. Since there is more room on a runway than on an aircraft carrier, land-based systems take more distance to stop aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/3510/1696&quot;&gt;The system is not used for every landing&lt;/a&gt;, but is useful to have in certain situations. For normal landings or aborted takeoffs, the system on the departure end will be used to prevent a runway overrun. If an aircraft needs to make an emergency landing, it will use the system closest to the approach threshold. Some cable systems are able to retract into a recess in the runway when not in use, &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/faqs/arrestingsystems.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;which prevents issues when aircraft roll over it&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the system is deployed in normal use, the tower will advise aircraft that the departure end cable is up. The departing aircraft will generally be in the air by the time it reaches the cable, but in case of a late rotation or aborted takeoff, the pilots can anticipate running over the cable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arresting gear is indicated on the FAA airport diagram as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/r57Vd.png&quot; alt=&quot;Arresting gear symbols&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://aeronav.faa.gov/content/aeronav/online/pdf_files/legendAD.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cable is marked by &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5220_9a.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;10-foot diameter yellow circles&lt;/a&gt; on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HIRb9.png&quot; alt=&quot;Yellow circles on runway&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: Google Maps&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-12T21:54:35.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12640" PostTypeId="5" CreationDate="2015-02-12T21:23:12.593" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-12T21:23:12.593" LastActivityDate="2015-02-12T21:23:12.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12641" PostTypeId="4" CreationDate="2015-02-12T21:23:12.593" Score="0" Body="A system that helps to stop an aircraft after landing. Typically a cable engaged by a hook on the aircraft." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-12T21:23:12.593" LastActivityDate="2015-02-12T21:23:12.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12642" PostTypeId="1" AcceptedAnswerId="12655" CreationDate="2015-02-13T00:28:43.853" Score="10" ViewCount="1747" Body="&lt;p&gt;One thing I noticed when reading through the &lt;a href=&quot;http://www.avialogs.com/en/aircraft/usa/mcdonnelldouglas/kc-10-extender/t-o-1c-10-k-a-1-flight-manual-kc-10a-aircraft-part-1.html#download&quot; rel=&quot;nofollow&quot;&gt;KC-10 flight manual (see page 184 for the specific reference)&lt;/a&gt; is that the KC-10 lacks support for Category III operations, unlike its civil DC-10 brethren.  What was the purpose behind the USAF asking MDC to remove capability from a military airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, military ILS systems in the US are qualified to CAT II at best, even in areas where air carrier airports are well-qualified for CAT IIIb minima.  For instance, Joint Base Lewis-McChord only has &lt;a href=&quot;http://155.178.201.160/d-tpp/1502/00414I34C2.PDF&quot; rel=&quot;nofollow&quot;&gt;a CAT II approach to RWY 34&lt;/a&gt; whereas nearby Seattle-Tacoma Int'l has CAT IIIb approaches to 300' RVR on all three of its &lt;a href=&quot;http://155.178.201.160/d-tpp/1502/00582I16CC2_3.PDF&quot; rel=&quot;nofollow&quot;&gt;primary&lt;/a&gt; &lt;a href=&quot;http://155.178.201.160/d-tpp/1502/00582I16LC2_3.PDF&quot; rel=&quot;nofollow&quot;&gt;instrument&lt;/a&gt; &lt;a href=&quot;http://155.178.201.160/d-tpp/1502/00582I16RC2_3.PDF&quot; rel=&quot;nofollow&quot;&gt;runways&lt;/a&gt;.  Considering that I seriously doubt the USAF would somehow be buying ILS equipment &lt;em&gt;inferior&lt;/em&gt; to what's available in the civil market -- is there some other reason they don't provide &lt;em&gt;any&lt;/em&gt; low-visibility capability better than the CAT II minima of 100' DH and 1/4 mile visibility, as the published PAR minima in the A/FD are no better, either?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: KADW RWY 19R has a &lt;a href=&quot;http://airnav.com/depart?http://155.178.201.160/d-tpp/1610/00561I19RC3.PDF&quot; rel=&quot;nofollow&quot;&gt;CAT IIIa approach&lt;/a&gt;, good to 700' RVR.  This seems to be the only military CAT III procedure published, though.  Perhaps the VIP airlift aircraft (E4, etal) have autoland support, even though the normal military heavies don't?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="15311" LastEditDate="2019-10-18T06:33:42.693" LastActivityDate="2019-10-18T06:33:42.693" Title="Why would the USAF have no support for autolanding?" Tags="&lt;military&gt;&lt;instrument-procedures&gt;&lt;ils&gt;&lt;us-air-force&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12643" PostTypeId="2" ParentId="12642" CreationDate="2015-02-13T01:26:12.230" Score="4" Body="&lt;p&gt;&lt;em&gt;NB: speculation, IANAP&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the assault strip in the approach diagram for McChord Field.  This is a very short strip of moderately improved runway for &lt;a href=&quot;http://www.amc.af.mil/news/story.asp?id=123173523&quot; rel=&quot;nofollow&quot;&gt;simulating a combat landing on a short airfield&lt;/a&gt;.  Most (if not all) USAF pilots need to qualify regularly with such landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike commercial aircraft, which take off and land almost exclusively at improved facilities, military aircraft should not expect ILS landings in their travels.  We've seen recently how over-reliance on automated technologies can have &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow&quot;&gt;disastrous results&lt;/a&gt;, in most cases fatal.  Thus the military places the emphasis on training the pilot, and not in relying on their equipment not to fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why put ILS systems at military airfields at all?  For one, many military airfields also serve as regional airports.  They might also give pilots proficiency in landing at commercial airfields.  It is also likely that they exist as a minimum for commercial pilots to use in the event of an emergency landing (for military-only runways).&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-02-13T01:26:12.230" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12644" PostTypeId="1" AcceptedAnswerId="12647" CreationDate="2015-02-13T01:33:19.940" Score="10" ViewCount="475" Body="&lt;p&gt;Considering the current diversity of coalition air fleets in some parts of the world (the Horn of Africa situation comes to mind), can Russian-built tankers refuel NATO probe-and-drogue receivers, and vice versa? (Say, a US Navy F/A-18E getting a helping hand from an Indian Air Force Il-78MKI, or an Ethiopian Air Force Su-27 filling its tanks from a Royal Australian Air Force A330 MRTT?)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-10-19T08:19:03.853" Title="Russian-built and NATO (USN, European) probe-and-drogue -- are they interoperable?" Tags="&lt;military&gt;&lt;refueling&gt;&lt;tanker&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12645" PostTypeId="2" ParentId="12642" CreationDate="2015-02-13T01:54:39.303" Score="11" Body="&lt;p&gt;FWIW, I do not fly the KC-10, but I do have friends that do...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, you're looking at a T.O. that is 7 years old since the last change (not sure when the most recent write-in is)...  Military pubs are always changing, avionics upgrades are always happening, and what you're looking at may be severely outdated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, I don't believe in this instance that it is.  However, I don't see the need to be able to shoot CAT IIIc approaches.  What does the Air Force gain?  Once deployed you aren't going to have that technology, and CONUS you just divert.  So why spend the money for it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I may not know the full politics behind it, but I do not see the operational need for it.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-13T01:54:39.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12647" PostTypeId="2" ParentId="12644" CreationDate="2015-02-13T09:27:16.663" Score="6" Body="&lt;p&gt;The drogue system was standardized in the 50s and reverse engineered by the USSR in that time so nearly all aircraft that use it are compatible with each other.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-02-13T12:29:03.397" LastActivityDate="2015-02-13T12:29:03.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12648" PostTypeId="1" AcceptedAnswerId="12672" CreationDate="2015-02-13T10:04:35.513" Score="9" ViewCount="1715" Body="&lt;p&gt;As a passenger, when I look out of the window, I can see the wings shaking. What would another plane (not in turbulence) see if they were observing the same plane (in turbulence)?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="65" LastEditDate="2015-02-13T15:29:57.193" LastActivityDate="2015-02-14T19:55:25.207" Title="Can an outside observer tell if an aircraft is flying through turbulence?" Tags="&lt;turbulence&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12649" PostTypeId="2" ParentId="12648" CreationDate="2015-02-13T15:36:55.523" Score="7" Body="&lt;ol&gt;&#xA;&lt;li&gt;The wings are flexing because there is a change in lift.&lt;/li&gt;&#xA;&lt;li&gt;The wings are more aerodynamic than the body of the aircraft. I.e. the wings are more &quot;responsive&quot;, they respond to changed aerodynamic forces more rapidly.&lt;/li&gt;&#xA;&lt;li&gt;As a result of the change in lift in the wings, the body (being connected to the wings) follow the change.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Therefore, to an observer who is immune to turbulence, the wings would flex first, followed by the aircraft as a whole. If the turbulence is causing the wings to flex up and down repeatedly (e.g. imagine sine wave), the body of the aircraft can be observed lagging behind the wings and smaller in amplitude.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-02-13T15:36:55.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12650" PostTypeId="2" ParentId="12648" CreationDate="2015-02-13T15:51:48.600" Score="4" Body="&lt;p&gt;Let's suppose you stand on an unstable bar stool. It shakes a little when you move, but you feel a lot of movement. An observer standing close by will see the stool and you shake a little bit (a few inches at most). If that observer moves a 100 feet away, he might not notice the shaking at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the airplane you are on is in turbulence&lt;sup&gt;1&lt;/sup&gt;, you will feel a lot of shaking. The airplane &lt;em&gt;is&lt;/em&gt; shaking, but to an outside observer which is close, it will feel as much as you feel it. Again, if the observer is moved a mile away, the shaking will not appear as significant as your experience.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;em&gt;Minor turbulence. In case of severe turbulence, it will be more evident to an observer.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-13T15:51:48.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12651" PostTypeId="2" ParentId="12634" CreationDate="2015-02-13T18:49:48.917" Score="5" Body="&lt;p&gt;I use x-plane and its great if you realize what you are using it for. I will offer some notes on various aspects of the software &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Hardware:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before I get into the software I assume you are using some kind of a yoke and rudder pedals. If you are not it is well worth getting a yoke (or stick), throttle, and pedal setup this will mimic what you find in a plane and will help you gain some muscle memory.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight mechanics:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get some very real planes on here and X-Plane gives you a great way to see what happens with certain control inputs. The only thing you cant really get is control force. A real plane (I fly small GA stuff) will apply force on the yoke that you will have to trim off. Although X has trim and it works nicely you cant trim based on control force so I find that I over trim in the sim often. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane its self will behave very closely to what it does in real life. I use X to practice landings and approaches as it gives a nice feel of what will show on what instruments.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Navigation:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is perhaps one of the best powers of X, you can get really good practice tracking VOR's in the sim and just get accustomed to what you need to do and when you need to do it. This will help you in the navigation stage of training. When I am running something in the sim I use my current paper charts and X has everything just as it is on the chart.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Landmarks:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fly in the PA area and the landmarks, even when flying at a very low resolution setting, are very accurate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Checklists:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only things you cant check is the exterior of the plane. But all of your interior check lists you can do. I have a sim saved that starts at my FBO with the engines off, check everything, start them up, taxi out, run up check, and take off all in the sim. You can also use it for things like engine out practice and various emergency procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is that the sim is not perfect, you wont feel what you feel in a real plane but its a great training tool and has really helped me to understand flight mechanics and the overall operation of the plane. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-02-13T18:49:48.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12652" PostTypeId="2" ParentId="1798" CreationDate="2015-02-13T21:42:10.430" Score="18" Body="&lt;p&gt;Short answer: Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: There are two ways to prevent the radar energy from being reflected back to its source in order to avoid detection:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Absorption, and&lt;/li&gt;&#xA;&lt;li&gt;Directed reflection.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Absorbers work well only over a small wavelength band, so some reflection is unavoidable. Now the idea is to collect all reflected energy along specific directions, so the aircraft will reflect very little energy in all other directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radars can adjust their sensitivity, and if they operate at their most sensitive setting, they will detect many false positives, but also a stealth aircraft. If the stealth aircraft maneuvers, it will momentarily shine one lobe of the reflected radar energy back at the radar receiver, causing it to reduce sensitivity such that the weak returns in all other directions will not be registered. Compare this to a diamond which will reflect light back at specific angles, causing it to sparkle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two-lobe designs (Northrop YF-23 and B-2) and four-lobe designs (Lockheed F-117 and F-22), but the idea is the same in all cases. Reflected radar energy is focused in narrow beams, so very little is given off in all other directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not to say that such aircraft can evade detection. When the radar stations are networked, they can pretty well trace those sparkles and stitch together the aircraft's location. Also, NATO aircrews which had participated in international maneuvers were less than impressed with the stealth capabilities of their colleagues, but were under a gagging order to be more specific.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is infrared. What does it help to be invisible on radar if the aerodynamic heating of the leading edge can be picked up by an IR receiver from 300 km away? When B-2s were flown over to the Farnborough airshow, British Eurofighters could detect them far out over the Atlantic already.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-14T06:03:20.930" LastActivityDate="2015-02-14T06:03:20.930" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12653" PostTypeId="2" ParentId="12619" CreationDate="2015-02-14T02:28:00.240" Score="1" Body="&lt;p&gt;A point to bear in mind with all of these, is that it doesn't take much for flight cancellations if your airport is already running very close to capacity with no time to makeup earlier delays. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This notably is the case with Heathrow where NATS (UK ATC) will be trialling time based separation over the current distance based separation between aircraft. Here's a good explanation from them about the impact of headwinds on landing rates and how measures like this can mitigate some of these impacts: &lt;a href=&quot;http://www.nats.aero/tbs/&quot; rel=&quot;nofollow&quot;&gt;http://www.nats.aero/tbs/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7315" LastActivityDate="2015-02-14T02:28:00.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12654" PostTypeId="2" ParentId="9925" CreationDate="2015-02-14T02:44:01.670" Score="3" Body="&lt;p&gt;One more for you: an SAS DC-8 crash landed in Santa Monica bay in January of 1969. Most of the crew and passengers survived, using the on-board life rafts. There were some issues as two of the rafts were punctured by debris. The survivors (30 out of 45 aboard) were rescued after about an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cause was controlled flight into terrain resulting from flight crew failures and a series of issues including an inoperative nose gear light which distracted the crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail struck first and broke off, sinking immediately. My dad had been a purser for the airline in the late 1940s and I remember him telling me that one of the victims sitting in the crew seats in the tail was an old friend with whom he had flown. My dad was pretty upset to lose a friend this way.&lt;/p&gt;&#xA;" OwnerUserId="3211" LastActivityDate="2015-02-14T02:44:01.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12655" PostTypeId="2" ParentId="12642" CreationDate="2015-02-14T02:56:41.633" Score="9" Body="&lt;p&gt;The Super Hornet can't even shoot a VOR approach, much less an ILS. We are TACAN/ PAR only.  That's fine at the boat, because that's how we operate, but apparently the Navy still hasn't figured out that there are stationary airfields that don't float.  Maybe someday we'll upgrade and get the finest in 1980's technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all seriousness I'm assuming it has to do with operational requirements and money.  The less the Navy spends on stuff like ILS equipment, the more they can spend on stuff that goes boom.  Also, if the weather is questionable at home we probably can't safely do our training mission anyway, and out at sea, we have some other systems that help us land on the boat in bad weather.  It would be really nice though to be able to use civilian fields as legal weather alternates.  It gets a little tricky sometimes when planning cross countries.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-02-14T02:56:41.633" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12656" PostTypeId="1" CreationDate="2015-02-14T03:43:01.660" Score="10" ViewCount="2738" Body="&lt;p&gt;Vertical take off is a big advantage, but why it is only limited to low weight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, fixed wing like An225 can lift more than hundred tonnes of payload, while the biggest helicopter is 25 tonnes. Why there is no effort to build a helicopter can lift 50 - 100 tonnes. What limits them? Economic or technical problem? I guess it is a technical problem because even the heaviest helicopter is just an experiment, but what is it?&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="13197" LastEditDate="2016-04-18T14:09:49.917" LastActivityDate="2017-04-06T08:33:04.023" Title="Why is vertical take-off restricted to lighter weight aircraft?" Tags="&lt;helicopter&gt;" AnswerCount="5" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12657" PostTypeId="1" AcceptedAnswerId="12661" CreationDate="2015-02-14T04:38:24.447" Score="5" ViewCount="1574" Body="&lt;p&gt;Why are most canard fighter aircraft unstable?  A stable design would let the canard provide lift.  My guesses are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Increase pitch rate&lt;/li&gt;&#xA;&lt;li&gt;Decrease stability while supersonic (supersonic, the aircraft are stable)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-10-07T20:36:45.843" Title="What advantages are provided by an unstable canard configuration for fighters?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12658" PostTypeId="1" CreationDate="2015-02-14T05:30:57.310" Score="8" ViewCount="7525" Body="&lt;p&gt;Magnesium is lighter than aluminum for the same strength.  If the answer is corrosion, how much work has been done to improve the corrosion resistance of magnesium?  How much lighter would a magnesium structure be than an equivalent aluminum structure?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2016-08-16T21:53:30.053" Title="Why is magnesium not used more often as a structural metal in aircraft?" Tags="&lt;airframe&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12659" PostTypeId="1" CreationDate="2015-02-14T05:32:46.937" Score="4" ViewCount="1153" Body="&lt;p&gt;I read somewhere (sorry don't remember where) that canards controls for missiles are more effective than tail controls.  Is this true, and if so, why?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-02-14T18:29:20.760" Title="Which type of control gives a more agile missile, tail or canard?" Tags="&lt;flight-controls&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12661" PostTypeId="2" ParentId="12657" CreationDate="2015-02-14T06:16:08.633" Score="5" Body="&lt;p&gt;You want your control surface to create only little lift, so it has enough margin for maneuvering. This confirms your first guess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your second guess is also correct: Flying supersonically shifts the center of pressure back and increases stability. If the aircraft is unstable subsonically, it will suffer far lower trim losses supersonically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please read all about unstable designs in &lt;a href=&quot;https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on/8061#8061&quot;&gt;this answer&lt;/a&gt;. For conventional, stable configurations it makes most sense to put the control and damping surfaces at the back, and a canard is the better choice for unstable, highly maneuverable aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-02-14T06:16:08.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12663" PostTypeId="2" ParentId="12656" CreationDate="2015-02-14T12:16:34.680" Score="24" Body="&lt;p&gt;Essentially it comes down to supersonic rotor tips&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a plane, in theory you can make it pretty much as big as you like - as long as you have strong/light enough materials, and can keep adding power, an aeroplane design scales pretty well. Bigger wing = more lift. As long as you can make the wing bigger without it breaking, and as long as you can add enough power to overcome the extra drag, there aren't many fixed limits&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a helicopter, we're limited by the rotor tips: once they go supersonic, they cause a lot of problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how does a helicopter produce lift? By using rotors to push air down within a kind of circle. To add more lift we can do (essentially) three things.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Make the rotor spin faster, so it pushes more air down in the circle it already uses. Obviously this makes the tips spin faster, so we can only do it to a certain extent. We've already hit this limit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Make the rotor blades longer, so they push a bigger circle of air. Again, though, due to the nature of a circular blade, the outside of a blade is moving faster than the inside. For a certain rotor speed, there's a fixed limit to how large the blades can be. Again, we've already hit this limit&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Add more blades, so there are more blades producing lift. This works to an extent (hence why smaller helicopters may have two rotor blades, but larger ones have 4, 5 or more. Again, though, this doesn't scale indefinitely - each rotor interferes with the next, you can't just keep adding more&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are other slight modifications we can make, such as the airfoil of the rotor, but they don't add significant gains&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically, we've hit the limit of what we can lift with a single rotor, The only real way to add more lift now is to add more rotors: doing that would be far less efficient than simply using an aeroplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which brings me to the final point - helicopters are very inefficient and pretty slow... We simply don't need, except in a few niche circumstances, to carry more weight with them.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-02-14T12:16:34.680" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12664" PostTypeId="2" ParentId="12656" CreationDate="2015-02-14T13:34:45.247" Score="8" Body="&lt;p&gt;Jon's answer is correct: &quot;helicopters are very inefficient and pretty slow...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but he misses one important point: helicopters are also incredibly fragile and delicate. Even a regular single-rotor helicopter flying is a miracle. It's been called: &quot;10,000 spare parts flying in close formation.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could add more rotors to gain more lift, the Chinook has two rotors which is part of why it can carry so much. The rear rotor adds complexity but also removes the need for a tail rotor, which is why it isn't quite 20,000 spare parts flying in close formation.  But even Chinooks are fragile compared to C-130s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding engines adds redundancy in a plane. And remember that if you are in a plane and you lose an engine (or all engines) you can still fly or glide to a safe landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in a rotorcraft and you lose your engine (either main rotor or tail) or really any single part of those 10,000 parts, then all you can do is pray and try an auto-rotation landing.  It gets worse the more rotors you add, not better. This is one of the limitations of rotorcraft and why you for the most part only see multiple rotors (4-, 6-, 8-) used in unmanned drones except for some very experimental vehicles.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-02-16T17:09:25.963" LastActivityDate="2015-02-16T17:09:25.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12665" PostTypeId="1" AcceptedAnswerId="34936" CreationDate="2015-02-14T14:36:33.793" Score="22" ViewCount="2832" Body="&lt;p&gt;If the takeoff weight is underestimated, rotation will be done too early and may result in a case of tail strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example of such mistake is a 747-400 (F-HLOV) in 2006 (case 8 in &lt;a href=&quot;http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Acc%20-%20Incident%20-%20IATA%20Flight%20Crew%20Computer%20Errors%20Case%20Studies%20Oct%202011.pdf&quot;&gt;this study&lt;/a&gt;). The crew entered ZFW for TOW (100 tons lower), VR was underestimated by 32 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_04/textonly/tr01txt.html&quot;&gt;Boeing documentation&lt;/a&gt; mentions every aircraft can be subject to tail strike, at different degrees. Airbus documentation for &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/195.pdf&quot;&gt;tail strike prevention&lt;/a&gt; doesn't mention any specific protection from FBW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dRF2k.jpg&quot; alt=&quot;747 Taking Off&quot;&gt;&#xA;(source: &lt;a href=&quot;http://avherald.com/h?article=42b2d053&quot;&gt;The Aviation Herald&lt;/a&gt;.)&lt;br&gt;&#xA;UA B744 tail strike on Sydney takeoff (photo may not be the actual May 7th 2010 T/O).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I wonder why such basic mistake may be done. Weight could be sensed in some way by the instrumentation, and crew entered values should be challenged if really different. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To prevent the crew from being forced (or tempted) to rotate the aircraft beyond the maximum safe angle, isn't that possible to monitor the T/O progress and in case of low performances alert the crew, and provide an opportunity to reject the T/O.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airbus FWB embeds many security systems (compared to Boeing), this is surprising that they cannot prevent such T/O tail strikes. I'm sure there are good reasons, just asking to understand the difficulty.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: Based on the answer from Marky Mark, who references the EK407 case, I checked a study published in the aftermath of EK407 tail strike: &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1748.pdf&quot;&gt;Take-off performance calculation and entry errors: A global perspective&lt;/a&gt; and noted this recommendation for 'TOPMS':&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While the above recommendation does not preclude data entry and&#xA;  calculation errors relating to take-off performance parameters from&#xA;  occurring, Transport Canada (Department of Transport) agreed that a&#xA;  take-off performance monitoring system(s) (TOPMS) would provide a&#xA;  significant safety benefit. However, before regulatory authorities&#xA;  establish a requirement for the fitment of TOPMS, a certified system&#xA;  would need to be developed (Transport Canada, 2010).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Basically, a TOPMS, which assists pilots in determining whether to&#xA;  continue or reject the takeoff, can be defined as (Brown &amp;amp; Abbasi,&#xA;  2009, p. 7).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Are TOPMS now in place?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-02-16T09:06:16.523" LastActivityDate="2017-01-26T18:47:01.717" Title="Could fly-by-wire protect against a takeoff tail strike?" Tags="&lt;takeoff&gt;&lt;airbus&gt;&lt;fly-by-wire&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12666" PostTypeId="2" ParentId="12659" CreationDate="2015-02-14T16:13:52.690" Score="11" Body="&lt;p&gt;Since the control unit sits at the tip of the missile, it is simply more practical to control it via canard deflections. The rear part can then be made as a simple pressure vessel with fixed fins and a nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the rear fins would have to move, their actuators would either be in the way of the nozzle flow or would stick out on the outside - in both cases performance would suffer. Also, long cable runs along the side of the missile would need to be added.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By controlling the missile with the forward fins, any change of direction will be direct, whereas control via the rear fins means that the rear end of the missile would initially move away from the desired direction, until the change in attitude would move the missile towards its target. Thus, the canard will result in a more agile missile.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-14T18:29:20.760" LastActivityDate="2015-02-14T18:29:20.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12667" PostTypeId="1" AcceptedAnswerId="12676" CreationDate="2015-02-14T17:10:27.710" Score="17" ViewCount="11089" Body="&lt;p&gt;I was reading one of the documents linked on &lt;a href=&quot;https://aviation.stackexchange.com/questions/12665/could-fly-by-wire-protect-against-a-takeoff-tail-strike&quot;&gt;this question&lt;/a&gt;, particularly I was reading case study number 8 of &lt;a href=&quot;http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Acc%20-%20Incident%20-%20IATA%20Flight%20Crew%20Computer%20Errors%20Case%20Studies%20Oct%202011.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this particular document&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the conclusion the author notes that the aircraft flight characteristic calculations had been messed up to the point that all V-speeds were calculated for a 747 100 tons lighter than their actual Take Off Weight (TOW).  Thus, they tried to rotate too early, couldn't get enough lift and the tail of the 747 struck the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When reading that brief description, I had assumed that perhaps they were off by 5 to 8 knots, or something along those lines.  So, I was surprised to see the author later note that V&lt;sub&gt;r&lt;/sub&gt; was actually off by close to 30 knots!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm really curious suddenly, how much can a 747's rotation speed change?  I was told that rotation speed was generally somewhere around 130 knots for that class of plane, but if there is a 30 knot variance. Can it really be anywhere from 115 to 145 depending on the weight of the plane?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-17T23:13:35.660" Title="In a 747 is it normal for the Vr (takeoff speed) to vary greatly depending on fuel load and ambient temperature?" Tags="&lt;takeoff&gt;&lt;boeing-747&gt;&lt;v-speeds&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12669" PostTypeId="2" ParentId="12658" CreationDate="2015-02-14T17:38:01.867" Score="11" Body="&lt;p&gt;Magnesium has initially been held back by technical difficulties in the removal of chloride inclusions. These had been solved only after a lot of progress had been made in aluminum alloys. Also, magnesium parts should only be used in a dry environment - when the metal is exposed to water, rapid corrosion must be expected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first application of magnesium in aerostructures was in the 1930s (mostly under the trade name &lt;a href=&quot;http://en.wikipedia.org/wiki/Elektron_(alloy)&quot;&gt;Elektron&lt;/a&gt;), with a small boom in the 1950s. Lockheed even &lt;a href=&quot;http://www.transport-research.info/Upload/Documents/201205/20120511_143246_34445_PAPER%20-%20PRESENT%20STATE%20AND%20FUTURE%20OF%20MAGNESIUM%20APPLICATION.pdf&quot;&gt;built one F-80C fully from magnesium&lt;/a&gt;. Magnesium was widely used in the former Soviet Union, but eventually phased out in newer designs due to corrosion problems. Flammability, by the way, was never a real concern with magnesium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With improved protection techniques, magnesium might make a limited come-back. It is already used in castings and extruded parts. Per kilogram, it is twice as expensive than aluminum, but very easy to machine. However, at higher temperature it will lose strength even faster than aluminum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parallel to that, aluminum sheet can be made lighter and stiffer by adding up to 2.5% of lithium. These &lt;a href=&quot;http://en.wikipedia.org/wiki/Aluminium-lithium_alloy&quot;&gt;Al-Li alloys&lt;/a&gt; have found their way into the newest aircraft designs and will raise the bar for magnesium applications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Magnesium and water really don't mix well: Trying to extinguish a magnesium fire with water is a memorable experience, as adding water will intensify the reaction. Use iron chips or sand instead to cool down the burning metal and to keep oxygen away. Historically, though, magnesium fires on aircraft have been extremely rare.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-14T17:51:56.657" LastActivityDate="2015-02-14T17:51:56.657" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12670" PostTypeId="1" CreationDate="2015-02-14T18:17:38.650" Score="1" ViewCount="437" Body="&lt;p&gt;I was wondering if airline companies have a Chief Medical Officer who is in charge of the well-being of passengers. For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;in timing the lights on/off moments on intercontinental flights;&lt;/li&gt;&#xA;&lt;li&gt;timing and type of food served, to support periods of sleep, wake and disembarcation;&lt;/li&gt;&#xA;&lt;li&gt;airconditioner procedures, to ensure passenges don't get sick from too cold airconditioners (for example when the captain released power from the engines to the airconditioners after take-off, while the cabin crew had set it to min-min on an insufficient EPU at a hot airfield, it happily started blowing 10 degrees C in my neck);&lt;/li&gt;&#xA;&lt;li&gt;methods and moments of desinfecting the air/passengers when contagious diseases break-out (or a flu epidemic in the US, with all its internal air-traffel);&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6832" LastEditorUserId="5568" LastEditDate="2015-02-15T02:00:20.573" LastActivityDate="2015-02-15T04:54:30.767" Title="Do airline companies have a Chief Medical Officer?" Tags="&lt;passenger&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12671" PostTypeId="1" AcceptedAnswerId="12679" CreationDate="2015-02-14T18:20:54.390" Score="16" ViewCount="16004" Body="&lt;p&gt;Surely, mid-air refueling is a cool thing, but is it worth it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's obvious that the military, for one, has some requirements to keep aircraft airborne so that they can keep patrolling, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, that is due to the need to keep the aircraft airborne and is not necessarily because the method is cost-effective.&#xA;Flying another aircraft carrying lots of fuel just doesn't seem very money/environment-friendly &amp;ndash; you waste more fuel needed to power the fuel-carrying aircraft in addition to the fuel you would already need.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is mid-air refueling cost-effective under any circumstances? Or is it just an emergency practice?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7339" LastEditorUserId="946" LastEditDate="2015-02-15T09:56:07.647" LastActivityDate="2015-04-26T08:33:45.607" Title="Why is mid-air refueling worth it? (or is it at all?)" Tags="&lt;military&gt;&lt;refueling&gt;" AnswerCount="14" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12672" PostTypeId="2" ParentId="12648" CreationDate="2015-02-14T19:55:25.207" Score="4" Body="&lt;p&gt;The wings act as a structural dampener to disturbances such as turbulence, similar to the suspension on a car. As they flex, they absorb the sudden energy changes. The aerodynamic forces also take time to accelerate the large mass of the airplane. Because of these effects, most of turbulence will be too small to see from an outside observer's point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in addition to the wing flexing, the aircraft will also roll, pitch, and yaw in response to the turbulence. The pilots or the autopilot, as well as the natural stability tendencies of the aircraft, will help the aircraft return to its previous state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://youtu.be/odDsaLzPkgI&quot; rel=&quot;nofollow&quot;&gt;Here is a video&lt;/a&gt; recorded from the X-Plane flight simulator program of a 737 in turbulence. The wing flex and change in flight attitude can be seen.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-14T19:55:25.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12673" PostTypeId="2" ParentId="12671" CreationDate="2015-02-14T20:00:52.273" Score="22" Body="&lt;p&gt;It's not a question of saving money, or emergencies. The reason militaries use mid-air refueling is so they can reach anywhere in the world. Aircraft have a limited range, without mid-air refueling they would have to have enough fuel to get to and from their area of operations back to a base. This would limit where military aircraft (or espionage aircraft) could reach, even with bases all over the world. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With mid-air refueling aircraft can fly great distances from their bases over any territory, complete their mission, and get back. It greatly increases a military air force's capability. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-02-14T20:00:52.273" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12674" PostTypeId="2" ParentId="7853" CreationDate="2015-02-14T20:13:40.943" Score="8" Body="&lt;p&gt;So, given Terry's remarks, GdD pointing out that the density altitude for Ovda is around 4300', and the current &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_4.pdf&quot;&gt;B744 Airport Planning Document&lt;/a&gt;, we can use the unadjusted (there's also a temperature adjusted version, but you don't need that when you have a density altitude in hand) T/O distance chart for the appropriate engine type (I'm going to use the CF6 version for example's sake) to compute how heavy a 747 out of Ovda can be.  (The chart you need is on page 72 on the PDF, by the way.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking across the chart at the 10,000' line gets you an intersection with the 4000' altitude curve about halfway between 750,000 and 800,000 lbs; let us call this 775,000 lbs for argument's sake.  Since we have a slightly shorter runway and a somewhat higher DA, 760,000 lbs is a reasonable MTOW for a 744 out of Ovda; if you wished to be extra conservative, you could cap your MTOW at 750,000 lbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per PDF page 15 of that same document, the typical operating empty weight of a B744 is about 394,000 pounds.  Adding the 120,000 pounds of passengers Terry quoted onto this leaves you with 236,000 lbs of fuel minimum, which is more than enough to get to anywhere in Europe with fuel to spare.  If you want figures, you can use the payload/range charts on PDF page 55 to get a max range of 4200 miles, which as per the &lt;a href=&quot;http://www.gcmap.com/mapui?R=4200nm%40LLOV&quot;&gt;great-circle mapper&lt;/a&gt; is enough to get you to anywhere in Europe or Africa, as well as the Indian subcontinent and much of SE Asia and China.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the landing half of it, the landing distance charts on PDF pages 94 and 95 can be used, assuming a wet runway, a 4300' density altitude for Ovda, the passenger configuration MLW of 630,000lbs, and the ability to use Flaps 30 (Flaps 25 yields a longer landing distance) we get a runway length of around 8700'; this'd be somewhat tight (you'd want to use max autobrakes and your reversers, and make sure you came over the fence at Vref with a firm touchdown to avoid floating in ground effect), but passenger flights don't land at MLW very often, so it'd be a workable operation.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-02-14T22:07:38.440" LastActivityDate="2015-02-14T22:07:38.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12675" PostTypeId="2" ParentId="12671" CreationDate="2015-02-14T20:21:43.227" Score="25" Body="&lt;p&gt;First to the issue of cost-effectiveness: If fighter or strike aircraft would need to take more fuel with them, they would have to be larger and more fuel-hungry themselves. This is hard to quantify, but with air refuelling you can cap the size at  a much smaller value and still be sure that all future range and endurance requirements can be met.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, modern air campaigns are extremely complex. It takes months of planning for a single day of multi-national operations, and aircraft from several countries have to be staged at some distance to then fly their sorties with utmost precision. Air refueling makes it much simpler to do this planning, because it allows to build in waiting times or to use scarce ressources multiple times during a day. Take electronic countermeasures aircraft: Instead of flying back to a remote home base, the aircraft can refuel at an airborne tanker and be back to support the next wave of attacking aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And whoever said that concerns about their environmental impact have ever influenced the choice of means of the military?&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-02-14T20:21:43.227" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12676" PostTypeId="2" ParentId="12667" CreationDate="2015-02-14T20:57:25.267" Score="16" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/12677/1696&quot;&gt;As Henning Makholm's answer discusses&lt;/a&gt;, the weight difference between the lowest and highest weights is significant. The operating empty weight (OEW) of a 747-400 is 394,100 lb, while the maximum takeoff weight (MTOW) is 875,000 lb. This means there is a difference of about 400,000 lb between the lightest and heaviest weights at which a 747 may be taking off, making the MTOW about twice as heavy as the OEW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotation speed Vr is the point at which the aircraft can pitch up and develop enough lift to climb. So at MTOW, the 747 must develop about twice as much lift than closer to OEW. Most of this force is lift from the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift can be calculated with the &lt;a href=&quot;http://www.grc.nasa.gov/WWW/k-12/WindTunnel/Activities/lift_formula.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;following equation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;L = &lt;sup&gt;1&lt;/sup&gt;/&lt;sub&gt;2&lt;/sub&gt;ρv&lt;sup&gt;2&lt;/sup&gt;sC&lt;sub&gt;L&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;L = lift&lt;br&gt;&#xA;ρ = air density&lt;br&gt;&#xA;v = airspeed&lt;br&gt;&#xA;s = wing area&lt;br&gt;&#xA;C&lt;sub&gt;L&lt;/sub&gt; = lift coefficient&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air density will certainly play a role. Higher altitudes and temperatures reduce the amount of lift. But this example pertains to the other variables.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airliner can use flaps and slats to increase the &lt;em&gt;C&lt;sub&gt;L&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;s&lt;/em&gt; of its wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;C&lt;sub&gt;L&lt;/sub&gt;&lt;/em&gt; will also depend on the angle of attack &lt;em&gt;α&lt;/em&gt; of the wings. An approximate curve for the 747 can be seen &lt;a href=&quot;http://www.aerospaceweb.org/question/aerodynamics/q0252.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; (it's for a 747-200, but it should be close enough). When an aircraft rotates, it is changing the AOA, which increases the lift. It is very important when designing an aircraft to make sure it can pitch up enough while on the runway to achieve the pitch angle needed for takeoff. A 747-400 rotates to about &lt;a href=&quot;http://www.bangaloreaviation.com/2009/05/typical-takeoff-and-climb-angles-of-all.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;10 degrees&lt;/a&gt; on takeoff. Based on the approximate &lt;em&gt;C&lt;sub&gt;L&lt;/sub&gt;&lt;/em&gt;-&lt;em&gt;α&lt;/em&gt; diagram, the lift coefficient changes from about 0.3 to 1.25 when &lt;em&gt;α&lt;/em&gt; changes from 0 to 10 on rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft weight is increased, flaps may be increased from &lt;a href=&quot;http://www.bangaloreaviation.com/2009/05/typical-takeoff-and-climb-angles-of-all.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;10 to 20&lt;/a&gt;. However, flaps 20 may be standard because &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/114159/&quot; rel=&quot;nofollow noreferrer&quot;&gt;these guys said so&lt;/a&gt;, so lets assume that &lt;em&gt;C&lt;sub&gt;L&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;s&lt;/em&gt; will also not change. This leaves the airspeed &lt;em&gt;v&lt;/em&gt; as the only parameter left to increase lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.tc.faa.gov/its/worldpac/techrpt/ar04-44.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;In this study&lt;/a&gt;, figure A-7 shows a distribution of ground speed at liftoff that lies between 140 and 190 kts. These numbers will probably be a little higher than V&lt;sub&gt;r&lt;/sub&gt; due to the acceleration between V&lt;sub&gt;r&lt;/sub&gt; and liftoff, and an average headwind. This means that at weights at the lowest end, 130 kts would be a reasonable estimate for V&lt;sub&gt;r&lt;/sub&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now lets make up some numbers. Lets take the weights 475,000 lb and 875,000 lb. Assume that the aircraft needs a lift 10% higher than its weight to take off. This gives us lift values of 522,500 lb and 962,500 lb. Using the lift equation and a low end speed of 130 kts to find the unknown portion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;522500 = &lt;sup&gt;1&lt;/sup&gt;/&lt;sub&gt;2&lt;/sub&gt;ρ130&lt;sup&gt;2&lt;/sup&gt;sC&lt;sub&gt;L&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ρsC&lt;sub&gt;L&lt;/sub&gt; = 61.8&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since we are assuming none of those vales will change, we can solve for &lt;em&gt;v&lt;/em&gt; at the higher lift value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;962500 = &lt;sup&gt;61.8&lt;/sup&gt;/&lt;sub&gt;2&lt;/sub&gt;v&lt;sup&gt;2&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;v = 176 kts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not too much lower than the high end liftoff value of 190 kts. So there you have it. Lift must be increased to account for the additional weight, and lift is proportional to the square of the airspeed.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-02-14T23:28:25.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12677" PostTypeId="2" ParentId="12667" CreationDate="2015-02-14T20:57:54.190" Score="11" Body="&lt;p&gt;It doesn't sound surprising to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's more than a factor of 2 in difference between the empty weight and the MTOW of a 747-400, so one departing close to empty will be able to produce lift enough to climb away from the runway at a significantly lower speed than a fully-loaded one -- and therefore it &lt;em&gt;should&lt;/em&gt;, because (all other things being equal) the quicker you get to altitude, the shorter a window is there for sudden problems to be immediately dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since lift increases with the square of the airspeed, one would expect &lt;em&gt;v&lt;/em&gt;&lt;sub&gt;r&lt;/sub&gt; for an almost empty 747 to be less than 70% of that for the same aircraft at MTOW under similar conditions.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-02-14T20:57:54.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12678" PostTypeId="2" ParentId="12671" CreationDate="2015-02-14T22:20:50.920" Score="16" Body="&lt;p&gt;Cost effective?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look up the Black Bucks raids, then work out how much that refuelling cost.... Then compare that to the cost to the UK of losing the Falklands Islands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those raids were absolutely not possible without midair refuelling. Similarly Cold War patrols and reconnaissance missions. It's not about whether it's cost effective, it's about whether the mission can be undertaken without refuelling.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-02-14T22:20:50.920" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12679" PostTypeId="2" ParentId="12671" CreationDate="2015-02-14T23:52:26.160" Score="31" Body="&lt;p&gt;In some contexts, the economics depends on how special the aircraft you're refueling is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider  something like an AWACS mission. You have this very complex specialized aircraft, with a large, highly trained, crew &lt;em&gt;in addition to&lt;/em&gt; the flight crew. If you &lt;em&gt;didn't&lt;/em&gt; refuel that during the mission, it might need to spend a lot of its active hours being unproductive en route to and from the war. You would need &lt;em&gt;more of them&lt;/em&gt; (and more crews) to reach any given level of in-theater coverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand &lt;em&gt;with&lt;/em&gt; aerial refueling you need some tankers scuttling back and forth with fuel for your sentries. But they are cheaper and simpler to operate, cheaper and simpler to crew, and so forth. So even though you may use slightly more &lt;em&gt;aircraft hours&lt;/em&gt; in total, the total  &lt;em&gt;costs&lt;/em&gt; can be lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't hold to just the same extent for fighters and bombers, because they have to return to base from time to time to stock up on munitions anyway. There are still &quot;readyness&quot; types of missions it would be relevant for. The price tag for an F-35 seems to be in about the same ballpark as for a KC-767, but a KC-767 can service &lt;em&gt;many&lt;/em&gt; F-35s in a single mission, so having the tankers do the scuttling-back-and-forth can still be an economic win.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it's a good thing for a fighter that gets into combat &lt;em&gt;not&lt;/em&gt; to be lugging around enough fuel to get all the way home by itself.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-02-14T23:52:26.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12680" PostTypeId="2" ParentId="11378" CreationDate="2015-02-15T01:24:30.710" Score="3" Body="&lt;p&gt;Back when I went through USAF pilot training I remember being told our ejection seats had gyroscopes in the seat which would rotate the seat upright following an ejection.  Unable to find a source confirming this now, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although a self-righting seat wouldn't be effective against enemy weapons, it might help against mother nature.  And it's pretty cool technology.  The violence of an ejection is probably a more important threat than a later threat from an enemy (the enemy can't kill a crew member who doesn't survive the ejection).  Ejections from unusual attitudes do happen.&lt;/p&gt;&#xA;" OwnerUserId="2141" LastActivityDate="2015-02-15T01:24:30.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12681" PostTypeId="2" ParentId="12670" CreationDate="2015-02-15T04:54:30.767" Score="8" Body="&lt;p&gt;I'm not sure if every airline is the same. However each major airline I am familiar with does have a medical unit, usually headed by a doctor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, most of their efforts are actually dedicated internally - by that I mean looking after their employees. Things like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Assessing the employees ability to return to work after an injury or illness&lt;/li&gt;&#xA;&lt;li&gt;Fatigue management policy&lt;/li&gt;&#xA;&lt;li&gt;Assessing whether a certain condition is acceptable to work with&lt;/li&gt;&#xA;&lt;li&gt;Overseeing drug and alcohol rehabilitation (in some cases in Australia at least the employee is not automatically fired for being drunk/on drugs, they are allowed to complete a program and continue work)&lt;/li&gt;&#xA;&lt;li&gt;Occupational health and safety assessments&lt;/li&gt;&#xA;&lt;li&gt;General 'doctoring' duties for aircrew&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course they are also involved in passenger health policy development, but as I said - the majority of their work is dealing with their own staff (at least, this is from my viewpoint, but I may not be seeing the whole picture). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of an outbreak like you have mentioned, there is always an action plan ready to be put in place which is developed with the government health department (or CDC in USA). &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-02-15T04:54:30.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12682" PostTypeId="2" ParentId="12671" CreationDate="2015-02-15T04:58:04.237" Score="1" Body="&lt;p&gt;Lets say you're on a carrier and you want to bomb a target 200 miles inland.  What do you do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carriers normally stay a few hundred miles out to sea for safety--if they got too close they would be vulnerable to attack by Harpoonskis.  Oops, you don't have the fuel to reach your target with a load of bombs under combat conditions.  If you want to hit that target you're going to have to launch with tankers and you very well might need to meet tankers on the way back also.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-02-15T04:58:04.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12683" PostTypeId="1" AcceptedAnswerId="12706" CreationDate="2015-02-15T07:02:42.893" Score="4" ViewCount="6826" Body="&lt;p&gt;I recently switched to a G1000 equipped aircraft C182 and trying to figure out the specifics of the G1000 and how it works in the 182.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One that I can't really figure out with the manual and the POH  is the Electrical System&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have the following Indication (in flight around 30 min after takeoff)&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;M        BUS      E&#xA;28.0     VOLTS    28.0&#xA;&#xA;M        BATT     S&#xA;+1.5     AMPS     +0.3&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Does this mean that the main and the backup battery delivery 28 Volts?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The + Amps mean that the alternator is charging the batteries ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I noticed that the BATT Amps (M) never goes to 0 is that normal? I remember from the old analogue gauges that at some point they stay in the middle/0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are normal/acceptable values for BUS/BATT in a C182T?&lt;/p&gt;&#xA;" OwnerUserId="1957" LastEditorUserId="62" LastEditDate="2015-02-16T13:57:57.283" LastActivityDate="2017-11-21T12:10:12.393" Title="How do I interpret electrical system indications in a G1000 C-182?" Tags="&lt;electrical-system&gt;&lt;cessna-182&gt;&lt;g1000&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12684" PostTypeId="2" ParentId="12671" CreationDate="2015-02-15T07:41:30.780" Score="3" Body="&lt;p&gt;Thinking of it from logical standpoint, we can define the exact set of circumstances in which it would be cost effective to do this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The plane to be refueled is incapable of accomplishing its mission by going from any valid (=reachable given time and distance constraints) launch spot to any valid landing spot;&lt;br&gt;&#xA;AND&lt;br&gt;&#xA;2) The plane is capable of accomplishing its mission by going from any valid launch spot to a valid landing spot, if one or more refueling tankers can be got to some point along the route;&lt;br&gt;&#xA;AND&lt;br&gt;&#xA;3) The tanker(s) CAN get to that point along the route;&lt;br&gt;&#xA;AND&lt;br&gt;&#xA;4) The value of the mission is greater than the costs, even with the refuelling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also cases where these rules don't necessarily have to hold. For example, if a plane &lt;em&gt;can&lt;/em&gt; get to the target and back on its own power, but would have to fly a more dangerous route, the reduced risk of using a tanker may be worthwhile. At $2.4Bn per B2 bomber, a mere 0.04% reduction in mission risk is worth over a million dollars in hardware alone: not counting costs from failing the mission, payload value, potential lost-pilot-rescue costs, new-pilot-training costs, political costs, and opportunity costs for being one plane down.&lt;/p&gt;&#xA;" OwnerUserId="7235" LastActivityDate="2015-02-15T07:41:30.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12685" PostTypeId="2" ParentId="12671" CreationDate="2015-02-15T09:37:59.823" Score="5" Body="&lt;p&gt;In addition to other answers, tankers can provide specialization for their task -- i.e. circling for a long time where no one is shooting at you. Many military aircraft have to massively compromise fuel efficiency and capacity to do their job. Dedicated tankers tend to be variants of airliners; they have &lt;em&gt;lots&lt;/em&gt; of carrying capacity for fuel and can be designed with fuel efficiency as a concern. The other aircraft can then optimize for things besides fuel capacity, and don't need to worry so much about being extremely heavy and (for fighters) having unaerodynamic drop tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To use the SR-71 as an example, it couldn't carry much fuel at all and had horrendously inefficient engines (it was a plane that routinely cruised on afterburner) in order to do its job of flying faster and higher than anything else in the sky that wasn't a rocket. You could give it a high fuel capacity, but since it leaked fuel at lower speeds (the fuel tanks only sealed under thermal expansion) there wouldn't be much point, and you'd have to deal with a really heavy plane not optimized for low-speed flight during takeoff. However, the KC-135Q that refueled it did not have to fly at Mach 3, so it could be designed to be able to take off with plenty of fuel. You could not build a plane to do what the SR-71 was supposed to do &lt;em&gt;and&lt;/em&gt; be able to operate without tanker support; the designs for &quot;able to take off with all the fuel you'll need&quot; and &quot;able to do your job&quot; conflict, and the best way to resolve it is to split them into separate aircraft. So in that case, it would be far, far more expensive to build something to approximate the same capabilities without a tanker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The main reason, though, is what Jon Story said: Midair refueling is used when you have a job to do, not when you're trying to make money through your aviation operations. If you're trying to make money by flying things around, you wouldn't be doing the missions that require mid-air refueling. You only use it when your guiding principle is &quot;here's your job, here's a budget, go and do it,&quot; not &quot;go and make money the best way you can.&quot;)&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="923" LastEditDate="2015-02-15T09:55:14.230" LastActivityDate="2015-02-15T09:55:14.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12687" PostTypeId="2" ParentId="12657" CreationDate="2015-02-15T17:35:52.963" Score="4" Body="&lt;p&gt;Most modern fighter aircraft designs -not just canard-wing configurations- are designed to be (slightly) aerodynamically unstable. Stability is ensured through the action of the automatic control system, which issues commands to the control surfaces that stabilize the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The unstable aerodynamic design together with the digital control system makes the aircraft more maneuverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A safety feature with the canard providing a downforce for trim, is that the wing stalls before the canard in high angle of attack situations, which ensures that the aircraft still has maneuverability post-stall.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-02-15T17:35:52.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12688" PostTypeId="2" ParentId="12656" CreationDate="2015-02-15T17:39:42.263" Score="2" Body="&lt;p&gt;For a helicopter to take off vertically: $$Lift \gt Weight.$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weight grows with length to the third power ($l^3$, weight is proportional to volume) while the lift only grows with $l^2$, because it's proportional to the rotor blades planform area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More lift means higher lift coefficient and more rotorblade planform area. The maximum cirumferential speed at the blade tips is limited (there's the constraint that the tips can't move at supersonic speeds). One would need stiff longer and trapezoidal blades and there is a structural limit to the possible torque on the blade root.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft that cruise at high subsonic speeds exprience the same airspeed at any portion along the wings, unlike a helicopter that has a $v=r \omega$ relationship for the speed along the rotor blade. $v$ is constrained to subsonic speed. &lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorDisplayName="user7241" LastEditDate="2015-02-16T17:12:47.813" LastActivityDate="2015-02-16T17:12:47.813" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12689" PostTypeId="2" ParentId="12665" CreationDate="2015-02-15T18:00:48.840" Score="2" Body="&lt;p&gt;In principle, yes. The aircraft would have to be able to measure its weight, which rests on the main gear and front gear when on the ground. Measuring a structural displacement which increases with more weight and decreases with less weight, one could determine the aircraft weight.  &lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorUserId="1467" LastEditDate="2015-02-16T08:31:22.503" LastActivityDate="2015-02-16T08:31:22.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12691" PostTypeId="2" ParentId="12683" CreationDate="2015-02-15T18:57:41.107" Score="2" Body="&lt;p&gt;This all very much depends on the specific aircraft and how its set up but in general.. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;+Amps means that the system is charging (pushing current onto the batteries/across the ammeter reading the current in the system). An ammeter in a system is mainly to know if you are drawing from the batteries or pushing to them in other words indicating an alternator fault. I would say anything in the + range is fine. If you really want to test it out, next time you are in the plane (and able to) try running all the lights and electronics at the same time. If your current stays in the + or 0 then your alternator is supplying enough current to run everything at once. I would not worry about +.30 Amps and frankly I would look to see what the acceptable accuracy of that meter is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For voltage it sounds like your plane has a 24V system. Generally alternators run at a higher voltage so you can charge the battery. Again this reading is more to know of a failure. Your alternator most likely has a voltage regulator on it so you get a single (or close to it) voltage across the RMP range. Alternators will generate varying voltage across the RMP range so you need to smooth that out as you can damage or under power your electronics. If you start to see the voltage vary as you spin up the engine and slow it down you may have a bad alternator or voltage regulator. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-02-15T18:57:41.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12693" PostTypeId="1" CreationDate="2015-02-15T20:10:16.113" Score="18" ViewCount="2222" Body="&lt;p&gt;I know the number 1000 is just an arbitrary number that happens to have some zeros in it, but is there any non-economic obstacle to making a 1000 passenger aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, assume normal-ish space-per-passenger constraints, so &lt;a href=&quot;http://www.nytimes.com/1991/05/26/world/ethiopian-jews-and-israelis-exult-as-airlift-is-completed.html&quot;&gt;1087 people on a 747&lt;/a&gt; isn't really a 1000-passenger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="7324" LastEditorUserId="7324" LastEditDate="2015-02-15T20:16:38.250" LastActivityDate="2017-02-20T17:52:08.497" Title="Are there non-economic barriers to a 1000 passenger aircraft?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12694" PostTypeId="2" ParentId="12671" CreationDate="2015-02-15T20:16:04.717" Score="0" Body="&lt;p&gt;You either fly the airborne plane from it's current location to land/refuel and back to the previous current location, or make the refuelling plane do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, the same journey is being made.&lt;/p&gt;&#xA;" OwnerUserId="7325" LastActivityDate="2015-02-15T20:16:04.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12695" PostTypeId="2" ParentId="12693" CreationDate="2015-02-15T21:25:03.360" Score="2" Body="&lt;p&gt;Aside from finding a route that would make such a large aircraft profitable, the biggest barrier is probably that the existing infrastructure couldn't support such an aircraft.  Terminals would have to be enlarged to handle the enormous passage of 1,000 riders.  I'd guess that most taxiways probably aren't large enough either.  Even the A380 has run into trouble finding suitable airports to operate out of.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-02-15T21:25:03.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12696" PostTypeId="2" ParentId="12693" CreationDate="2015-02-15T21:37:12.913" Score="14" Body="&lt;p&gt;If money is no object, and we ignore terminal constraints, then no, there isn't. The A380 already supports 850 passengers in a single-class layout, and Airbus has &lt;a href=&quot;http://www.ausbt.com.au/airbus-confirms-a380neo-and-a380-stretch&quot;&gt;plans&lt;/a&gt; to make a stretched version (the wings are designed to give room to stretch the fuselage without needing too much redesign). 1000 passengers isn't really that much of a stretch; we can basically get there now. The issue is that economic obstacles are very real obstacles to building planes; no one has a need for a 1000-person plane on any route (the A380 isn't even used today with max capacity, it's used to give lots of space to first-class passengers with a bit over 500 passengers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are certainly at least two airfields out there that would be able to handle a 1000-passenger A380; unfortunately, neither is a commercial airport (the two are Edwards AFB and the Shuttle Landing Facility; the SLF has a 15,000 foot runway that's 300 feet wide, while Edwards has a similarly-sized paved runway). However, if operation is uneconomical, you won't see anyone building a plane to do it.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="923" LastEditDate="2015-02-15T21:42:57.387" LastActivityDate="2015-02-15T21:42:57.387" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12697" PostTypeId="2" ParentId="12665" CreationDate="2015-02-16T00:26:41.500" Score="10" Body="&lt;p&gt;On Airbus aircraft, the guidance law provides &lt;a href=&quot;http://www.a320typerating.com/howtoflyanairbus.html&quot;&gt;attitude protection&lt;/a&gt; on take-off which should prevent a tail strike. However, this is &lt;a href=&quot;http://blogs.crikey.com.au/planetalking/2009/03/21/emirates-leaves-its-mark-on-melbourne-and-vice-versa/&quot;&gt;not fool-proof&lt;/a&gt; and it remains up to the PF to maintain the correct nose-up angle.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-02-16T00:26:41.500" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12698" PostTypeId="2" ParentId="12671" CreationDate="2015-02-16T00:31:31.793" Score="0" Body="&lt;p&gt;Fuel is cheap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some more valuable resources that may be rendered useless or vulnerable during refueling include combat aircraft (which cost orders of magnitude more than refueling planes), nuclear missiles, training combat pilots or presidents.&lt;/p&gt;&#xA;" OwnerUserId="7132" LastActivityDate="2015-02-16T00:31:31.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12699" PostTypeId="2" ParentId="12671" CreationDate="2015-02-16T01:08:10.493" Score="1" Body="&lt;p&gt;It can be a regular non-emergency military practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One major early example was US airstrikes on the Hanoi area during the Vietnam war, which were launched from far to the south, and would refuel just before crossing into North Vietnamese airspace, so that the planes would have as much fuel available as possible during the mission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During air combat, particularly for aircraft who have missions that aren't just to go to one place and return immediately (e.g. to engage flying enemy aircraft), the amount of fuel carried (above what's needed to get there and back) determines the amount of time that aircraft can do tactically-useful things. Being able to top off closer to the target maximizes that time. For aircraft with afterburners, this also contributes to the amount of time they can use those, as using afterburners consumes fuel very quickly.&lt;/p&gt;&#xA;" OwnerUserId="3665" LastActivityDate="2015-02-16T01:08:10.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12700" PostTypeId="2" ParentId="9875" CreationDate="2015-02-16T04:41:12.893" Score="1" Body="&lt;p&gt;My flying school as recommended the &lt;a href=&quot;http://www.bobtait.com.au/store/product/32-rpl-book&quot; rel=&quot;nofollow&quot;&gt;RPL Study Guide by Bob Tait&lt;/a&gt; as the introductory text. It covers basic aviation plus Australian (CASA) regulations.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-02-16T04:41:12.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12702" PostTypeId="1" AcceptedAnswerId="12705" CreationDate="2015-02-16T12:40:41.167" Score="10" ViewCount="14365" Body="&lt;p&gt;I never saw these in the US, but certainly at UK airports and airfields you will often see &quot;RVP&quot; on a green background with a yellow border:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WAVJu.jpg&quot; alt=&quot;RVP Sign&quot;&gt;&#xA;&lt;sub&gt;Source: &lt;a href=&quot;http://www.sabre-roads.org.uk/gallery/displayimage.php?pos=-4476&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.sabre-roads.org.uk/gallery/displayimage.php?pos=-4476&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of these signs, and who/what is their intended audience?&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="8282" LastEditDate="2019-01-13T13:19:38.497" LastActivityDate="2019-01-13T13:19:38.497" Title="What are RVP signs?" Tags="&lt;airport&gt;&lt;uk&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12703" PostTypeId="2" ParentId="12671" CreationDate="2015-02-16T13:24:40.533" Score="0" Body="&lt;p&gt;Even if your fighter has to go half-way home to meet a tanker in the middle to refuel, that's half the journey it would otherwise have had to make. That's a &lt;em&gt;huge&lt;/em&gt; saving in time and if you want your plane to be close to where it needs to be then you don't really have much choice. You can't have it spending half its mission going back and forth between home bases.&lt;/p&gt;&#xA;" OwnerUserId="1931" LastActivityDate="2015-02-16T13:24:40.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12704" PostTypeId="2" ParentId="12693" CreationDate="2015-02-16T13:44:59.220" Score="14" Body="&lt;p&gt;Yes, there are some barriers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Scaling laws tell us that the structural mass fraction of such a big airplane would increase, reducing its efficiency.&lt;/li&gt;&#xA;&lt;li&gt;To evacuate 1000 passengers within 90 seconds from half of the available emergency exists will require clever engineering.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;First the scaling laws: When you increase the size of an aircraft, its area will grow with the square of the increase while its volume will grow with the cube of the increase. This demands proportionally bigger cross sections of all load-carrying members. For the same reason &lt;a href=&quot;http://en.wikipedia.org/wiki/Them!&quot;&gt;ants cannot be scaled up&lt;/a&gt; and elephants have much bigger legs than antelopes. The A380 is already pushing the envelope, and any bigger aircraft will be even more problematic to design. But not impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The emergency slides on the A380 were one of the most challenging parts to design. While normal slides can be mercifully short, lowering a passenger by 8 meters from the upper floor such that he or she will reach the ground at a survivable speed is hard. The slide must be much longer and still is not allowed to buckle. This required the development of new materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that this has been done, a stretched fuselage with another two or four &lt;a href=&quot;http://www.kls2.com/cgi-bin/arcfetch?db=sci.aeronautics.airliners&amp;amp;id=%3Cairliners.1997.835@ohare.chicago.com%3E&quot;&gt;type I exit doors&lt;/a&gt; will make the 1000 pax version possible. But when a future design plans to have a wider fuselage with more seats in a row, this will be one of the first limits to adding seats.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-02-16T13:44:59.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12705" PostTypeId="2" ParentId="12702" CreationDate="2015-02-16T13:55:35.600" Score="18" Body="&lt;p&gt;It's a Rendezvous Point for emergency vehicles. This is from the UK's &lt;em&gt;&lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP576.pdf&quot;&gt;Aerodrome Model Emergency Orders&lt;/a&gt;&lt;/em&gt; (appendix B, section 1.1.1):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rendezvous Point signs should be displayed at the point(s) designated&#xA;  by the Aerodrome Emergency Orders as the rendezvous point(s) for all&#xA;  responding Emergency Services. Signs should be clearly visible from&#xA;  any direction from which responding Emergency Service vehicles/&#xA;  personnel are likely to approach when attending aircraft&#xA;  accidents/incidents within the response area defined by or cross-&#xA;  referenced in the Aerodrome Manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-16T13:55:35.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12706" PostTypeId="2" ParentId="12683" CreationDate="2015-02-16T14:01:50.970" Score="3" Body="&lt;p&gt;You can find this in the &lt;a href=&quot;http://dpwiese.mit.edu/POH/C182T_IM_2004_navIII.pdf&quot; rel=&quot;nofollow&quot;&gt;C182T Operating Handbook&lt;/a&gt;. Section 3 has information about what values should be considered a malfunction:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;HIGH VOLTS ANNUNCIATOR COMES ON OR M BAT AMPS MORE THAN 40&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also says that the M bus should be at least 20 volts in normal operation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Main Battery supplies electrical power to the Main and Essential&#xA;  Buses until M BUS VOLTS decreases below 20 volts. When M BUS VOLTS&#xA;  falls below 20 volts, the Standby Battery System will automatically&#xA;  supply electrical power to the Essential Bus for at least 30 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 4 has the expected values when starting the engine:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;6&quot;&gt;&#xA;  &lt;li&gt;BUS E Volts&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;CHECK (Verify 24 VOLTS minimum shown)&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;M BUS Volts&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;CHECK (Verify&#xA;  1.5 VOLTS or less shown)&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;BATT S Amps&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;CHECK (Verify discharge shown (negative)&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 7-54 describes the electrical system in detail, including wiring diagrams. It says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Normal bus voltages with the alternator operating shall be about 28&#xA;  volts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Indicated voltages between&#xA;  24.5 and 28 volts may occur during low engine RPM conditions&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for the ammeter:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A positive current value (shown in white) indicates that the battery&#xA;  is charging. A negative current value (shown in amber) indicates that&#xA;  the battery is discharging. In the event the alternator is not&#xA;  functioning or the electrical load exceeds the output of the&#xA;  alternator, the main battery ammeter indicates the main battery&#xA;  discharge rate. In the event that Standby battery discharge is&#xA;  required, normal steady state discharge should be less than 4 amps.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So long story short, all the information you need is in the POH and the best way to get all the details is to read it carefully. Your POH may be slightly different from the one I've quoted here, so if there are any differences then you should follow it, not this answer.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-02-16T14:10:37.947" LastActivityDate="2015-02-16T14:10:37.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12707" PostTypeId="1" AcceptedAnswerId="12713" CreationDate="2015-02-16T15:00:43.247" Score="23" ViewCount="7234" Body="&lt;p&gt;Use of checklists is a 'special emphasis area' during FAA &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot;&gt;private&lt;/a&gt; and &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-12C.pdf&quot;&gt;commercial&lt;/a&gt; checkrides but there are a lot of comments in pilot forums about using flows instead, often - but not always - in the context of airline operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a flow, and what is the difference between a flow and a checklist? When should a pilot prefer one or the other? Or are they used together?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="100" LastEditDate="2020-05-06T13:00:28.670" LastActivityDate="2020-05-06T13:00:28.670" Title="What is the difference between a flow and a checklist?" Tags="&lt;safety&gt;&lt;checklist&gt;&lt;flow&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12708" PostTypeId="2" ParentId="12671" CreationDate="2015-02-16T15:09:54.393" Score="4" Body="&lt;p&gt;Technically, the purpose of inflight refuelling is to act as a force multiplier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say I have a requirement for a combat air patrol (two aircraft on station all the time) at a given location 250 miles away. The aircraft available have a range of 1000 miles and the ground turn-around takes the same time as flying 250 miles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I need two in the air going there, two on station, two coming back and two on the ground - minimum of 8 of which 6 are not patrolling. Now put up a tanker and  even with only one refuel per patrol I can now keep between 2 and 4 aircraft on patrol at all times with only 4 aircraft. &lt;/p&gt;&#xA;" OwnerUserId="2233" LastActivityDate="2015-02-16T15:09:54.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12709" PostTypeId="1" AcceptedAnswerId="12710" CreationDate="2015-02-16T15:44:51.217" Score="10" ViewCount="3877" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12665/could-fly-by-wire-protect-against-a-takeoff-tail-strike&quot;&gt;This question&lt;/a&gt; indicates that an early rotation can cause a tail strike. What are the (pre-)flight dynamics that would cause this to happen vs what happens when rotating at the proper time?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2020-10-31T13:52:32.973" Title="How does early rotation increase the likelihood of a tail strike at take off?" Tags="&lt;takeoff&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12710" PostTypeId="2" ParentId="12709" CreationDate="2015-02-16T16:10:38.067" Score="15" Body="&lt;p&gt;When preparing for a flight, pilots will calculate many things, including their rotation speed. This is the speed in their takeoff roll at which they will start to pitch up, and hopefully the plane &lt;a href=&quot;https://aviation.stackexchange.com/q/2786/1696&quot;&gt;lifts off the ground&lt;/a&gt;. The rotation speed is dependent on many things such as temperature, altitude, and aircraft weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My answer &lt;a href=&quot;https://aviation.stackexchange.com/a/12676/1696&quot;&gt;here&lt;/a&gt; discusses the lift calculations in relation to rotation. That question covered the importance of speed related to weight. More speed is needed to create the lift to take off with a higher weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the airplane rotates, it increases the angle of attack of the wing, which increases the lift coefficient (if the wing does not stall). The pilots will pitch up at a certain rate, and they do not stop until they reach a climbout attitude higher than what is possible when the main gear is still on the ground (&lt;a href=&quot;https://aviation.stackexchange.com/a/12725/1696&quot;&gt;though this may depend on company policy&lt;/a&gt;). They count on the plane acheiving enough lift during rotation to leave the ground so that they pass that maximum pitch while in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If pilots underestimate their weight, they will calculate a lower speed than is necessary to provide the lift for takeoff. This means that when they rotate, the plane doesn't have enough airspeed yet to create enough lift to take off. So instead of leaving the ground before fully pitching up, the tail strikes the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may seem like an easy mistake to make, but thousands of pilots do it every day without a problem.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-02-17T17:18:42.440" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12711" PostTypeId="2" ParentId="12709" CreationDate="2015-02-16T16:11:31.127" Score="6" Body="&lt;p&gt;If you rotate too early (that is, with too little airspeed), the plane will need to reach a higher than expected attitude before it begins rising from the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that the plane will be &lt;em&gt;closer to the runway&lt;/em&gt; than expected, starting from the attitude where it would normally have lifted off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, when it reaches an attitude where the tail is lower than the main gear (which is supposed to happen routinely during climbout), it may not yet be far enough above the runway that there is room for enough of the tail below a horizontal plane through the bottom of the wheels.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-02-16T16:11:31.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12712" PostTypeId="2" ParentId="12707" CreationDate="2015-02-16T16:49:31.353" Score="15" Body="&lt;h1&gt;Definitions&lt;/h1&gt;&#xA;&lt;p&gt;A &lt;strong&gt;flow&lt;/strong&gt; is like a fluid movement in specific directions across panels for a specific purpose, to set up the airplane. It is meant to be a muscle memory method.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/leadingedge/leading_edge_checklists_and_flows_194990-1.html&quot; rel=&quot;noreferrer&quot;&gt;Example:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qbBvq.jpg&quot; alt=&quot;Engine Fire&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rOWlY.jpg&quot; alt=&quot;Approach&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A &lt;strong&gt;checklist&lt;/strong&gt; is a &amp;quot;to do list&amp;quot;, which ensures that important and/or required steps are taken for a particular tasks.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BQTW8.jpg&quot; alt=&quot;Checklist&quot; /&gt;&lt;/p&gt;&#xA;&lt;h1&gt;Why one is chosen?&lt;/h1&gt;&#xA;&lt;p&gt;Flows are used to go through all checks of the aircraft without running through an actual checklist. Flows are to be memorized mostly by muscle memory, and kept at least semi-congruent in their execution.&lt;/p&gt;&#xA;&lt;h1&gt;Can they used together?&lt;/h1&gt;&#xA;&lt;p&gt;Yes.&lt;/p&gt;&#xA;&lt;p&gt;A flow contains information about how to quickly set up the airplane during different phases of flight. Pilots can speed through the steps of a flow. A flow may not be identical each time and can change according to situation, without omitting necessary steps.&lt;/p&gt;&#xA;&lt;p&gt;Flows can be verified by checklists to ensure that they are complete. Once pilots follow items in a checklist overtime, they will memorize the &lt;em&gt;key&lt;/em&gt; steps required for a particular task.&lt;/p&gt;&#xA;&lt;h1&gt;Final words&lt;/h1&gt;&#xA;&lt;p&gt;Flows can be rushed, checklists cannot. Steps can be omitted in flows, steps cannot be omitted in checklists.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;Further Reading:&lt;/em&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.flyaoamedia.com/aoa/the-mystery-of-flows-vs-checklists/&quot; rel=&quot;noreferrer&quot;&gt;The mystery of flows vs checklists&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.avweb.com/news/leadingedge/leading_edge_checklists_and_flows_194990-1.html&quot; rel=&quot;noreferrer&quot;&gt;Checklists and Flows&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://studentpilot.com/interact/forum/showthread.php?29300-Flow-vs-Checklist-Your-02&quot; rel=&quot;noreferrer&quot;&gt;Flow vs. Checklist Your $.02&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://letsgoflying.wordpress.com/2012/01/02/checklist-discipline/&quot; rel=&quot;noreferrer&quot;&gt;Checklist Discipline&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-16T18:19:37.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12713" PostTypeId="2" ParentId="12707" CreationDate="2015-02-16T17:39:36.447" Score="21" Body="&lt;p&gt;Generally speaking a checklist is an actual &lt;em&gt;list&lt;/em&gt; of items to &lt;em&gt;check&lt;/em&gt;, and a flow is a pattern of movement across the aircraft controls (switches, dials, etc.) which will accomplish some subset of the items on a checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flow should be essentially &quot;muscle memory&quot; for a pilot and performed by rote, where a checklist may be more detailed and include more specific guidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can probably tell flows and checklists are closely related (with flows usually being derived from checklists). The two are complimentary tools that are used together: A pilot will follow a flow, and then verify that the required items have been completed using the checklist.&lt;br&gt;&#xA;In larger/more complicated aircraft it's not possible to fully memorize some of the checklists, so flows are used to accomplish the &quot;red box&quot; immediate action items before proceeding to the full checklist.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a simple example, consider the engine power loss flow &amp;amp; checklist for a Piper Cherokee.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Engine Power Loss Flow (Red Arrow &amp;amp; Numbers)&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Mixture&lt;/strong&gt; (Set appropriately - usually &quot;Rich&quot;)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Throttle&lt;/strong&gt; (Set appropriately)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Carb Heat / Alternate Air&lt;/strong&gt; (On)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Magnetos&lt;/strong&gt; (Both)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Electric Fuel Pump&lt;/strong&gt; (On)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Primer&lt;/strong&gt; (In &amp;amp; Locked)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Fuel Selector&lt;/strong&gt; (On a tank that has fuel)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Manufacturer's Engine Power Loss Checklist (Blue Numbers)&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Fuel Selector - Switch to a tank containing fuel.&lt;/li&gt;&#xA;&lt;li&gt;Electric Fuel Pump - On&lt;/li&gt;&#xA;&lt;li&gt;Mixture - Rich&lt;/li&gt;&#xA;&lt;li&gt;Carb Heat - On&lt;/li&gt;&#xA;&lt;li&gt;Engine Gauges - Check for an indication of the cause of power loss&lt;/li&gt;&#xA;&lt;li&gt;Primer - Check Locked.&lt;/li&gt;&#xA;&lt;li&gt;If no fuel pressure is indicated  check tank selector position to be sure it is on a tank containing fuel.&lt;/li&gt;&#xA;&lt;li&gt;Ignition Switch - &quot;Left&quot; then &quot;Right&quot; then back to &quot;BOTH.&quot;&lt;/li&gt;&#xA;&lt;li&gt;Throttle and Mixture - Different settings.&lt;br&gt;&#xA;(This may restore power if problem is too rich or too lean a mixture, or a partial fuel system restriction.)&lt;/li&gt;&#xA;&lt;li&gt;Try another fuel tank.&lt;br&gt;&#xA;(Water in the fuel could take some time to be used up, and allowing the engine to windmill may restore power. If power loss is due to water, fuel pressure indications will be normal.)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/akSqP.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/akSqP.png&quot; alt=&quot;Flow &amp;amp; Checklist illustrated on panel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In this example the flow accomplishes nearly all the checklist items, but it does so moving over the panel in one direction. As a practical matter the flow is accomplished by just moving your hand along the bottom of the panel: &quot;Push the mixture. Push the throttle. Pull the carb heat. Twist the mag key. Flip all the switches UP (on). Pull the primer and make sure it doesn't move. Move the fuel selector lever to the other tank.&quot;&lt;br&gt;&#xA;Completing the flow takes less than 10 seconds and can be done with one hand while your other hand is pitching for best glide speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer's checklist for an engine power loss moves around the panel in a more haphazard way, but it also adds a few items (checking the engine gauges &amp;amp; fuel pressure indication), and provides more specific guidance on possible causes like fuel contamination (water in the fuel) &amp;amp; how to deal with them. These items could be important if the memory items from the flow don't restore engine power, assuming you have time (altitude) to spend troubleshooting them.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-16T17:39:36.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12714" PostTypeId="1" CreationDate="2015-02-16T17:46:51.243" Score="51" ViewCount="18364" Body="&lt;p&gt;Is it right that basically an airplane just needs to accelerate to climb?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Greater velocity of an airplane leads to greater lift - and since its weight remains constant (or even decreases) - a greater lift leads to a gain in altitude without the need to pitch. But why do airplanes climb by &quot;pointing the nose up&quot;? Is it to climb as fast as possible and to need less horizontal space?&lt;/p&gt;&#xA;" OwnerUserId="7331" LastEditorUserId="1696" LastEditDate="2015-02-24T15:58:31.773" LastActivityDate="2020-04-12T10:00:26.160" Title="Why do airplanes lift up their nose to climb?" Tags="&lt;aerodynamics&gt;" AnswerCount="11" CommentCount="13" FavoriteCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="12715" PostTypeId="2" ParentId="12671" CreationDate="2015-02-16T18:12:04.920" Score="3" Body="&lt;p&gt;I'll build on &lt;a href=&quot;https://aviation.stackexchange.com/a/12679/1444&quot;&gt;@HenningMakholm's excellent answer&lt;/a&gt;.  Mid-air refueling brings lots of cost-benefits beyond the obvious &quot;make planes go farther&quot;.  First, tankers can provide operational flexibility and efficiency compared to having to set up closer airbases.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You don't have to set up a closer airbase.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You don't have to build it.&lt;/li&gt;&#xA;&lt;li&gt;You don't have to conquer and secure that space (very costly).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Your airbases can be farther away from the front lines.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Immune from artillery and ground attack.&lt;/li&gt;&#xA;&lt;li&gt;More layers of air defenses.&lt;/li&gt;&#xA;&lt;li&gt;More warning of air attack.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You don't have to keep moving and rebuilding your airbases as the front line moves.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;And all their fuel, ordinance, personnel, hangars, buildings, bunkers, defenses...&lt;/li&gt;&#xA;&lt;li&gt;You can respond faster to changes on the ground providing better support.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You can strike much, much deeper into enemy territory.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The enemy has a wider area to defend, spreading themselves thinner.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gulf_War_air_campaign#Vulnerability_of_Iraq_to_air_attacks&quot; rel=&quot;nofollow noreferrer&quot;&gt;Destroy their command and control and transportation&lt;/a&gt;, cripple the enemy, the war ends early, you save fuel, money, lives and suffering.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;You can attack from unexpected directions.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Put a tanker where you have no airbases, attack from that direction.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But does it save fuel?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Central point number one: &lt;em&gt;combat aircraft are inefficient, tankers are efficient&lt;/em&gt; and somebody has to drag that fuel out there.  Might as well be a tanker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While keeping a tanker in the air might seem like a waste of fuel, and it does have to burn fuel while in the air, it likely &lt;em&gt;saves&lt;/em&gt; a lot of fuel because tankers are so efficient and combat aircraft are so inefficient.  A tanker is typically based on a civilian airliner.  Once it's at altitude and in position, it can run racetrack laps at its most efficient speed and altitude (many combat aircraft have trouble going &lt;em&gt;slow&lt;/em&gt; enough for the tanker) sipping fuel compared to the ordinance laden (ie. lots of drag), high performance aircraft it's fueling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that very efficient tanker didn't drag that fuel out there, those same laden, inefficient combat aircraft would have to and this leads to what is known as &lt;a href=&quot;http://www.nasa.gov/mission_pages/station/expeditions/expedition30/tryanny.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Tyranny Of The Rocket Equation&lt;/a&gt; which says to carry more fuel you need &lt;em&gt;even more fuel&lt;/em&gt;.  If you have a lot of inefficient aircraft, it can save fuel to have them take off with half empty tanks and top up at an efficient tanker on the way.  The Rocket Equation is so tyrannical you can save fuel even in civilian flights, &lt;a href=&quot;http://aerosociety.com/News/Publications/Aero-Journal/Online/388/Operations-and-aircraft-design-towards-greener-civil-aviation-using-airtoair-refuelling&quot; rel=&quot;nofollow noreferrer&quot;&gt;here's a paper on the subject&lt;/a&gt; (sorry about the paywall).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Central point number two: &lt;em&gt;make as few combat trips as possible to destroy a target&lt;/em&gt;.  A plane can only carry so much, and more fuel means less weapons.  Less weapons means more trips.  More trips means more fuel.  More importantly it means more times the pilot and airframe are exposed to danger (and if you need to take two trips you've probably lost the element of surprise), and more aircraft needed to attack the same number of targets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take off is another consideration.  Taking off and climbing to altitude is one of the most fuel hungry parts of a flight.  Combat and long haul aircraft typically take off near maximum weight requiring full engine power and a long climb.  Taking off with less fuel means you burn less fuel getting to altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heavier aircraft need a longer runway to take off from.  That runway length may not be available at your forward base, or it may be damaged.  Less fuel means heavier weapon loads with shorter runways which means more flexibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combat aircraft can only carry so much fuel internally before they need drop tanks.  Drop tanks add drag making the aircraft less fuel efficient and generally maneuver like a pig.  Drop tanks also take up precious hard point space for weapons which means more round trips which means... you get the idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You &lt;em&gt;can&lt;/em&gt; take this idea too far.  The biggest problem with the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;nofollow noreferrer&quot;&gt;F/A-18 Hornet&lt;/a&gt; was its measly fuel load.  The long ranges typically required at sea meant it practically required a tanker to operate effectively.  Carriers can't carry big tankers, so they had to resort to inefficient &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_refueling#Buddy_store&quot; rel=&quot;nofollow noreferrer&quot;&gt;buddy packs&lt;/a&gt; mounted on smaller aircraft.  This problem was resolved with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet&quot; rel=&quot;nofollow noreferrer&quot;&gt;F/A-18 Super Hornet&lt;/a&gt; which is practically a different aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1444" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-04-09T14:47:21.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12716" PostTypeId="2" ParentId="12714" CreationDate="2015-02-16T18:22:28.930" Score="1" Body="&lt;p&gt;Because most of the lift comes from the angle of attack (AoA) of the wings. Higher AoA means more lift (up to a point).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also most aircraft will pitch up as they increase speed due to design.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-16T18:22:28.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12717" PostTypeId="2" ParentId="2555" CreationDate="2015-02-16T19:12:19.250" Score="8" Body="&lt;p&gt;Passengers like information and even if some do not, it isn't much an inconvenience to hear it anyway.  That information is a matter of tradition as far as I can tell.  It is written nowhere in my manuals what is to be said in the boarding PA except some general guidelines on how to conduct yourself on the PA system.  PA announcements you've heard have the cruising altitude, and the captain showing a new first officer how to do the boarding announcement will include that information.  That first officer will go on to include the cruise altitude and when he is a captain he'll pass it along to his first officers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you took a look at every pilot individually you'll find that the vast majority of each pilots boarding announcements are exactly the same (aside from things that vary like the specific cruise altitude and weather information).  After saying the announcement a few times you settle into a routine and it perpetuates.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-02-16T19:12:19.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12718" PostTypeId="2" ParentId="12714" CreationDate="2015-02-16T19:13:33.343" Score="28" Body="&lt;p&gt;Consider the relative airflow. When an airplane is not climbing, the relative airflow is horizontal, and so the angle at which the air meets the wings, ie the angle of attack, is measured from the horizon (Case A in the diagram). However, when an air-plane is climbing, the relative wind is tilted downward by the climbing component of the airplane's velocity. If the airplane did not tilt the nose up, the angle of attack would approach zero as the rate of climb increased, reducing lift and efficiency (Case B), so the air-plane must tilt up the nose to keep the angle of attack in an efficient range (Case C). !&lt;img src=&quot;https://i.stack.imgur.com/gvGUn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7333" LastEditorUserId="7333" LastEditDate="2015-02-16T19:43:50.913" LastActivityDate="2015-02-16T19:43:50.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12720" PostTypeId="2" ParentId="12714" CreationDate="2015-02-16T20:14:18.410" Score="58" Body="&lt;p&gt;A climbing aircraft needs less aerodynamic lift than in horizontal flight, not more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have your attention, I hope. The reason is quite simple:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift equals weight, and just because the pilot choses a different flight path angle, the weight of the aircraft does not change. The total of all lifting forces must still balance the weight, but in climb you get a small lifting contribution from the engine(s) because its (their) thrust will point upwards just like the rest of the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7vD23.png&quot; alt=&quot;Forces and their angles acting on a climbing aircraft in side view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't let the many arrows and greek letters confuse you. To be in equilibrium, lift (L, dark blue), drag (D, red), thrust (T, green) and weight (m⋅g, black) must add up such that they can be combined into a closed run of vectors. I've done this with the lighter-colored vectors around the weight. Since the flight path points upwards, so does the thrust which now has a small vertical component. The lift vector can be a little shorter now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the extreme case of vertical climb: Now all thrust supports the weight, and aerodynamic lift is no longer needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a second, much more subtle effect: When you climb, air gets thinner and engine performance goes down proportionally. At the same indicated air speed, the aircraft will continually decrease its climb speed, and this deceleration frees up a tiny inertial force, which again adds to lift and counteracts weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, at the beginning of a climb phase the aircraft needs to create momentarily more lift to accelerate itself upward. Only then, when climb speed increases, lift must be bigger than weight to overcome the inertial effect which at this moment works downwards. For the supernerds: If you integrate the lift deficit over time of the aforementioned effect and the extra lift over time for climb acceleration, both cancel exactly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To answer your question directly:&lt;/strong&gt; To climb you need to increase excess energy, not speed. This is normally done by increasing engine power output, or by trimming the airplane at a lower speed where drag is less, so more power remains for climbing. &lt;a href=&quot;https://aviation.stackexchange.com/questions/12096/relationship-between-power-and-fuel-efficiency&quot;&gt;This question&lt;/a&gt; contains more details on how to get an aircraft to climb. Note especially @SteveV.'s bucket analogy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use the airplane's kinetic energy as its source of thrust, the same mechanism can be applied to instationary climbs, where speed is traded for altitude, like in gliders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose-up attitude is simply the result of a different flight path. Since the required aerodynamic lift will be almost the same, the angle of attack will also be almost the same and the whole aircraft needs to fly nose-up. This is similar to a car which has the same attitude towards the road, but when you drive uphill, both car and road will be tilted upwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This analogy breaks down when you change speed - flying at lower speed needs more angle of attack to still create the same lift, and this nose-up change will be added to your attitude angle.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-10T09:35:30.927" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="12722" PostTypeId="1" AcceptedAnswerId="12723" CreationDate="2015-02-16T21:20:38.543" Score="12" ViewCount="1062" Body="&lt;p&gt;&lt;em&gt;Pressure Pattern Navigation&lt;/em&gt; is a method of capturing favorable tailwinds when flying long-distance trips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic methodology can be found &lt;a href=&quot;http://williams.best.vwh.net/smxgigpdf/smx2001c.pdf&quot;&gt;in this PDF&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine that airline captains aren't all that free to choose their routes (correct me in the comments if I'm wrong!), but this seems to be perfectly suited for the corporate and charter crews among us. However, I've never heard of any crews using it in real life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Does pressure pattern navigation work in the real world? How effective is it?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="65" LastEditDate="2015-02-16T22:09:59.367" LastActivityDate="2015-02-17T07:26:33.330" Title="Is pressure pattern navigation used in the real world? How effective is it really?" Tags="&lt;navigation&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12723" PostTypeId="2" ParentId="12722" CreationDate="2015-02-16T22:11:32.417" Score="17" Body="&lt;p&gt;It is used in the real world, especially by airlines. The best example is the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot;&gt;North Atlantic Track system&lt;/a&gt;. The tracks are tailored every day to maximize the tailwind on West to East crossings and minimize the headwind East to West crossings. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-02-16T22:11:32.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12724" PostTypeId="1" AcceptedAnswerId="12729" CreationDate="2015-02-17T06:35:16.073" Score="31" ViewCount="20192" Body="&lt;p&gt;Generally speaking, for those that either have experience calling &lt;em&gt;the number&lt;/em&gt;, or, preferably, for those that were paid to answer the phone, what are the benefits or pitfalls of calling?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had a friend that climbed above his assigned altitude once and was given the number, and he called and had an exceptionally friendly chat, and that was that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any scenarios, such as gross violations, where it might be better to seek legal counsel first before calling, or not calling at all--especially if there is a discrepancy between airman and controller?&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="62" LastEditDate="2015-02-17T14:42:44.487" LastActivityDate="2018-12-12T06:53:46.597" Title="What should you do when ATC gives you a number to call to discuss a violation?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;air-traffic-control&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12725" PostTypeId="2" ParentId="12667" CreationDate="2015-02-17T07:18:06.610" Score="7" Body="&lt;p&gt;Below are the lowest and highest Vr listed for 747-100 and -200 aircraft with the engines shown for a flaps 10 normal takeoff. They are from the Tower Air (now long defunct) QRH that pilots and engineers were issued.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;JT9D-3A  110 to 174&#xA;JT9D-7A  114 to 177&#xA;JT9D-7F  115 to 179&#xA;JT9D-7J  118 to 180&#xA;JT9D-7Q  126 TO 182&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The actual tables are lengthy, with the Vr varying according to takeoff weight, flap setting, temperature, pressure altitude, as well as at least one other thing I cannot offhand remember. Each cell of the table gives V1, Vr, V2, and the 3-engine rotation target. Lowest weight, of course, gives you the lowest Vr.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The f.e. grease-penciled the values he looked up on a plastic card, which he then passed to the f.o., who checked them. When the f.o. was satisfied they were correct, he propped the card against the instrument panel in front of the thrust levers. The captain could choose to accept them at face value or check them himself as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the two 747 carriers I worked, there was a difference in culture as to how you were to rotate. At the first carrier, you rotated to 10 degrees nose up and held that attitude until you came off the ground, at which time you rotated to the 3-engine rotation target. This procedure was intended to prevent tail strikes. At Tower Air they taught the correct procedure (in my opinion) of rotating directly to the 3-engine rotation target.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-02-17T23:13:35.660" LastActivityDate="2015-02-17T23:13:35.660" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12727" PostTypeId="2" ParentId="420" CreationDate="2015-02-17T08:39:54.610" Score="13" Body="&lt;p&gt;To calculate your possible climb speed $v_z$, you will need&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Your engine's thrust $T$&lt;/li&gt;&#xA;&lt;li&gt;Your airplane's drag $D$&lt;/li&gt;&#xA;&lt;li&gt;Your airplane's mass $m$&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Calculate how much power is needed to overcome drag, and any excess can be used for climbing: $$v_z = v\cdot sin\gamma = v\cdot\frac{T-D}{m\cdot g}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this equation makes use of several simplifications, but works well for propeller and slow turbofan aircraft with moderate flight path angles $\gamma$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To do this with more precision, you need to account for the fact that the aircraft should accelerate during the climb to stay at the same polar point. Now you further need:&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;4&quot;&gt;&#xA;&lt;li&gt;The gradient of air temperature over altitude (&lt;a href=&quot;http://en.wikipedia.org/wiki/Lapse_rate&quot; rel=&quot;noreferrer&quot;&gt;lapse rate&lt;/a&gt; $\Gamma$)&lt;/li&gt;&#xA;&lt;li&gt;The local speed of sound $a$, and&lt;/li&gt;&#xA;&lt;li&gt;The gas constant $R$ of air.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You need to add a correction factor $C$ which has several components: $$C = 1 + \frac{1}{2}\cdot\kappa\cdot R_w\cdot\Gamma_w\cdot Ma^2 + \frac{(1+0.2\cdot Ma^2)^{\frac{\kappa}{\kappa-1}}-1}{(1+0.2\cdot Ma^2)^{\frac{1}{\kappa-1}}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\kappa$ is the ratio of the specific heats of air and is 1.405, the index w denotes the wet adiabatic gas constant and lapse rate of air, and $Ma$ is your flight Mach number. $\Gamma$ can vary between -0.004°/m and -0.0097°/m, but if you use the average of -0.0065°/m, this equation can be simplified to: $$C = 1 - 0.13335\cdot Ma^2 + \frac{(1+0.2\cdot Ma^2)^{3.5}-1}{(1+0.2\cdot Ma^2)^{2.5}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which is probably the form you will find in most books which care to cover this topic. The second summand takes care of the reduction of atmospheric temperature with altitude and disappears in the stratosphere, and the third summand covers the additional energy needed for acceleration in terms of flight Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tmBBq.png&quot; alt=&quot;Graph of the acceleration factor over Mach number&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Acceleration factor over the flight Mach number in the troposphere for the Standard Atmosphere&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now your climb speed becomes $$v_z = \frac{v}{C}\cdot sin\gamma = \frac{v}{C}\cdot\frac{T-D}{m\cdot g}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see from the graph above, the correction factor is only important at higher speeds, but will cut the climb speed in half at Mach 2. Some jet aircraft need to climb at a high constant Mach number, and then the aircraft needs to decelerate while climbing. Now the correction factor becomes smaller than unity and the climb speed gets a boost because kinetic energy is converted into potential energy while climbing.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Optimum speeds&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To pick the flight speed where the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8365/difference-between-best-rate-of-climb-and-maximum-rate-of-climb/8368#8368&quot;&gt;climb speed or the fight path angle reaches a maximum&lt;/a&gt;, you now need to describe how thrust will change with flight speed. To simplify things, we can say that thrust changes over speed in proportion to the expression $v^{n_v}$ where $n_v$ is a constant which depends on engine type. Piston aircraft have constant power output, and thrust is inverse with speed over the speed range of acceptable propeller efficiencies, hence $n_v$ becomes -1 for piston aircraft. Turboprops make some use of ram pressure, so they profit a little from flying faster, but not much. Their $n_v$ is -0.8 to -0.6. Turbofans are better in utilizing ram pressure, and their $n_v$ is -0.5 to -0.2. The higher the bypass ratio, the more negative their $n_v$ becomes. Jets (think J-79 or even the old Jumo-004) have approximately constant thrust over speed, at least in subsonic flow. Their $n_v$ is around 0. Positive values of $n_v$ can be found with ramjets - they develop more thrust the faster they move through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight speed for maximum rate of climb ($v_y$) is reached at a lift coefficient $c_L$ of $$c_L = -\frac{n_v+1}{2}\cdot\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\cdot \sqrt{\frac{(n_v+1)^2}{4}\cdot\left(\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\right)^2 + 3\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;whereas the steepest climb is possible with a $c_L$ of $$c_L = -\frac{n_v}{4}\cdot\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\cdot \sqrt{\frac{n_v^2}{16}\cdot\left(\frac{T\cdot\pi\cdot AR\cdot\epsilon}{m\cdot g}\right)^2 + c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient&lt;br&gt;&#xA;    $T \:\:\:\:$  thrust &lt;br&gt;&#xA;    $m \:\:\:\:$  aircraft mass &lt;br&gt;&#xA;    $g \:\:\:\:\:$  gravity &lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-30T19:29:29.533" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12728" PostTypeId="2" ParentId="12724" CreationDate="2015-02-17T14:13:34.253" Score="3" Body="&lt;p&gt;From an article in &lt;a href=&quot;http://www.flyingmag.com/&quot; rel=&quot;nofollow&quot;&gt;Flying magazine&lt;/a&gt; by an aviation lawyer: (quoting from memory, the issue was pre-internet):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In many cases the FAA cannot take any action against you without your&#xA;  co-operation. So don't give them any. For example, you are required to&#xA;  show (not surrender) your license to an inspector upon request. He&#xA;  doesn't get to touch it. And if you are asked &quot;was that your 182&#xA;  flying down the beach last Saturday?&quot; your cause is best served by&#xA;  silence. Will that make them happy? No. But which would you rather&#xA;  have? An angry FAA official who cannot suspend your license, or a very&#xA;  happy one who can?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Regarding the &quot;number to call&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once you have left the aircraft movement area you are no longer air&#xA;  traffic and therefore no longer bound to follow their instructions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He also had this to say about the NASA Air Safety Reporting System:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;It is not a coupon good for one free buzz job.&lt;/li&gt;&#xA;  &lt;li&gt;Keep several in your flight bag. Fill them out. Keep the receipt - it has powers similar to a cross on a vampire.&lt;/li&gt;&#xA;  &lt;li&gt;Be concise to a fault. &quot;Landed short&quot; will cover &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow&quot;&gt;Asiana 214&lt;/a&gt;.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2590" LastEditorUserId="65" LastEditDate="2015-02-18T19:07:07.397" LastActivityDate="2015-02-18T19:07:07.397" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12729" PostTypeId="2" ParentId="12724" CreationDate="2015-02-17T14:36:57.593" Score="26" Body="&lt;p&gt;AOPA has &lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=6615&quot;&gt;an article&lt;/a&gt; on exactly this question (written by an attorney). Their advice is basically that it's a judgement call on your part and one that you should think about carefully. Not calling may antagonize the FAA, but calling if it's a major safety issue may be unwise:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;That doesn't necessarily mean, however, that you should call the&#xA;  telephone number or respond to the FAA's letter, and blather the most&#xA;  expansive defense you can conjure up. A little judgment is called for&#xA;  here--and, unfortunately, there are no hard and fast rules. If you&#xA;  think the FAA may be inclined to just admonish you orally or content&#xA;  itself with administrative action, then a humble, cooperative approach&#xA;  may be best. Saying you won't talk without a lawyer, when the likely&#xA;  outcome if you do talk is minor, may only prompt the FAA to propose&#xA;  sterner action. Before you talk, however, think carefully about what&#xA;  you want to say, how much to say, what questions the FAA is likely to&#xA;  ask and how you'll answer them.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If, on the other hand, there is a substantial chance the FAA will take&#xA;  certificate action against you or will propose a fine, the best course&#xA;  of action, as I said above, is to hire an attorney. Don't ignore the&#xA;  FAA; be polite, but don't provide more information than the bare&#xA;  outlines of what is already known and obvious to all. State quietly&#xA;  that you understand the FAA's desire to investigate possible&#xA;  violations, that you take your obligations to fly safely very&#xA;  seriously, and that you will be happy to cooperate. Also say that,&#xA;  unless the FAA is not contemplating action against you, you feel it&#xA;  best to consult a lawyer before proceeding. Since the FAA likely won't&#xA;  give you any guarantees, its representative will be the one&#xA;  overreaching if he presses you to respond anyway. Politely decline if&#xA;  he does.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I also had a look through the AOPA discussion forums (members only, so no links) and my summary of their comments would be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;File a &lt;a href=&quot;http://asrs.arc.nasa.gov/report/electronic.html&quot;&gt;NASA ASRS form&lt;/a&gt; within the 10-day limit, whatever happened&lt;/li&gt;&#xA;&lt;li&gt;If you know what you did wrong and you know it was minor, then make the call&lt;/li&gt;&#xA;&lt;li&gt;If you don't know what you did wrong then call but be prepared to end the conversation immediately if you have no good response or you realize it's more serious than you thought&lt;/li&gt;&#xA;&lt;li&gt;If you know you caused a major safety issue (actual or potential) then don't call and get a lawyer instead&lt;/li&gt;&#xA;&lt;li&gt;If you know the person you have to call  - e.g. if it's the tower controller at your home airport - then you should give more weight to calling&lt;/li&gt;&#xA;&lt;li&gt;In general, it's better to call and have to cut off the conversation than not to call in the first place&lt;/li&gt;&#xA;&lt;li&gt;Whatever you say, keep it short and factual&lt;/li&gt;&#xA;&lt;li&gt;When you find out what you did wrong, get some ground and/or flight training from an instructor to address that specific issue and have him endorse it in your logbook; this shows the FAA that you've taken the issue seriously and you've actively taken steps to make sure you won't do it again&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-02-17T20:00:47.183" LastActivityDate="2015-02-17T20:00:47.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12730" PostTypeId="1" CreationDate="2015-02-17T15:26:11.447" Score="9" ViewCount="31268" Body="&lt;p&gt;What is the passenger capacity of an A380, and how many suitcases could it carry?&lt;/p&gt;&#xA;" OwnerUserId="7342" LastEditorUserId="1696" LastEditDate="2015-02-17T16:16:53.900" LastActivityDate="2019-05-19T12:02:48.640" Title="How many passengers can an Airbus A380 carry?" Tags="&lt;airbus-a380&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12731" PostTypeId="2" ParentId="12730" CreationDate="2015-02-17T15:36:35.847" Score="11" Body="&lt;p&gt;In theory, up to a maximum &lt;strong&gt;853&lt;/strong&gt; passengers in a single-class setup (ie if the whole plane was set up for the maximum possible number of economy passengers)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, it's usually configured for &lt;strong&gt;525&lt;/strong&gt; in a typical &quot;three class&quot; (First, Business, Economy) layout, which is standard (with fairly minor variations) for most airlines as this is both more profitable to the airline, and better suited to actual real-world demand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the upper deck contains a small number of First Class seats (front) and a larger number of Business Class (rear)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sJcBk.jpg&quot; alt=&quot;A380 upper deck&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the lower deck contains all economy class passengers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rVaa7.jpg&quot; alt=&quot;A380 lower deck&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luggage isn't a limiting factor for the A380, as it can hold approximately one suitcase per passenger in the luggage hold, and a further 2-4 suitcases per passenger in the bulk hold (depending on whether other cargo is being carried)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a380family/specifications/&quot;&gt;Reference: airbus.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus has some vague plans to introduce a 1000-passenger all-economy (ie single class) &quot;stretched&quot; version of the A380, but these don't appear to be in the pipeline for production anytime soon. The A380 was originally designed with this in mind, though.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-02-17T16:28:09.753" LastActivityDate="2015-02-17T16:28:09.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12732" PostTypeId="2" ParentId="12730" CreationDate="2015-02-17T15:37:42.213" Score="21" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380&quot;&gt;Wikipedia&lt;/a&gt; lists three basic configurations for the A380-800:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;407-526 (3-class)&lt;/li&gt;&#xA;&lt;li&gt;644 (2-class)&lt;/li&gt;&#xA;&lt;li&gt;853 (1-class)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380_seat_configurations&quot;&gt;different airlines have different configurations&lt;/a&gt;. The lowest number of seats is Korean Air, with &lt;strong&gt;407&lt;/strong&gt;. The highest number of seats is Air France, with &lt;strong&gt;538&lt;/strong&gt;. &lt;a href=&quot;http://www.space.com/3917-emirates-a380s-establish-airliner-seat-record.html&quot;&gt;Emirates has discussed plans&lt;/a&gt; for a configuration with 644 seats but it does not appear on the list (&lt;a href=&quot;http://www.seatguru.com/airlines/Emirates_Airlines/Emirates_Airlines_Airbus_A380_B.php&quot;&gt;or on SeatGuru&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as baggage, &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/237441/&quot;&gt;this thread&lt;/a&gt; states that the A380-800 might carry 19 LD-3 containers of baggage, or 3002 cubic feet, which is for about 471 passengers. The bulk hold, which is for loose baggage, can hold 1,525 kg or 14.2 cubic metres (501.5 cubic feet), and the A380-800 can carry 8,000 kg of cargo in addition to a full passenger load &lt;a href=&quot;http://www.skycargo.com/english/about-us/our-fleet/&quot;&gt;according to Emirates&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.tripp.co.uk/luggage-help/19-size-guide&quot;&gt;An average suitcase&lt;/a&gt; is about 0.1 cubic meters in volume. If the bulk hold is 14.2 cubic meters, then it could theoretically fit 142 suitcases. But &lt;a href=&quot;http://traveltips.usatoday.com/baggage-requirements-international-airline-travel-12505.html&quot;&gt;an average suitcase&lt;/a&gt; weighs 50 lb, so 142 suitcases would weigh 3220 kg, which is over twice the weight capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The LD-3 containers add an additional 85 cubic meters of space, or 850 bags. This is a total of 942 bags, which for around 500 passengers sounds very reasonable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But wait, there's more! What if the rest of the cargo capacity was filled with luggage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emirates above claims a total of 12 PMC and 44 AKE of cargo capacity. The properties are as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://satco-inc.com/satco-products/air-cargo-pallets/pmc---96-in-x-125-in-standard/&quot;&gt;PMC&lt;/a&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;23 cubic meters (&lt;a href=&quot;http://www.searates.com/reference/pmc/&quot;&gt;max&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;6700 kg capacity&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://satco-inc.com/satco-products/air-cargo-containers/ake-ld3/&quot;&gt;AKE&lt;/a&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;4.3 cubic meters&lt;/li&gt;&#xA;&lt;li&gt;1497 kg capacity&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is a total of 465.2 cubic meters of capacity, or 4652 suitcases, or 105,505 kg. The containers could hold a maximum of 146,268 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the bulk plus container capacity is &lt;strong&gt;4794 bags&lt;/strong&gt; by volume. This is assuming every container could be packed completely full of bags with a density of 227 kg/cu m, so the actual numbers would probably be lower.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-02-17T16:30:00.277" LastActivityDate="2015-02-17T16:30:00.277" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12733" PostTypeId="2" ParentId="12714" CreationDate="2015-02-17T16:12:08.097" Score="0" Body="&lt;p&gt;Normally in an aircraft you change your altitude using the power. If you increase power, your altitude increases. If you reduce power the aircraft descends. In both cases the aircraft is normally at a near-level pitch angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this behavior is that the wing is permanently tilted upward by a certain amount, called the &quot;chord angle&quot; or &quot;angle of incidence&quot;. The angle is chosen so that in normal conditions, with medium power the aircraft will stay at the same altitude. If the wings were flat, the aircraft would tend to descend constantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main exception to the above is when you are taking off and want to gain altitude rapidly for safety reasons. In this case, the stick or yoke is pulled back and the aircraft tilts upward and climbs rapidly. What causes this is the elevator (or horizontal stabilizer) which is located on the tail of the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MGiNJ.gif&quot; alt=&quot;Elevator controls pitch&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The elevator allows the pilot to change the pitch of the wings. The more wing surface that is exposed to the air, the greater the upward force. You can demonstrate this yourself by holding your hand outside the window of a fast moving car. If you hold your hand level and then tilt the leading edge up, your hand will be forced upward by the wind, and vice versa. If you tilt the leading edge of your hand down, then your hand will be forced down by the wind. The same thing happens to an aircraft. &lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-02-17T20:33:53.523" LastActivityDate="2015-02-17T20:33:53.523" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12734" PostTypeId="2" ParentId="12724" CreationDate="2015-02-17T16:24:50.027" Score="0" Body="&lt;p&gt;I would tend to agree with paul's answer and be wary of Pondlife's answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases it is mistake to call them, because you are just providing them rope to hang you. If they have actionable evidence to revoke your license, calling them and confirming the information they have will just make it worse. If they do not have actionable evidence and are on a fishing expedition, then obviously it would be a blunder to call them. Basically the likely scenarios are all ones in which calling them is a mistake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only exception is when there is some fact which exonerates you completely that they do not know about it. Technically, you are better off presenting such a fact at a hearing, but in the interest of saving everyone's time and trouble, you may opt to reveal such a fact in the phone call. For example: &quot;I descended out of my asssigned altitude because I had an engine failure.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all honesty, the scenarios in which the call is useful are really rare, and as a rule you should &lt;strong&gt;NEVER&lt;/strong&gt; volunteer information regarding your actions in flight. Note that the worst the FAA can do is revoke your license, but another pilot could sue you for $5 million for &quot;endangering his life&quot;. Guess where he will get the evidence to sue you. From your statements to the FAA. Starting to see why it is a bad idea to be making statements to the FAA?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-02-17T23:05:38.880" LastActivityDate="2015-02-17T23:05:38.880" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12735" PostTypeId="1" AcceptedAnswerId="12739" CreationDate="2015-02-17T16:38:55.863" Score="3" ViewCount="11592" Body="&lt;p&gt;&lt;a href=&quot;http://www.law.cornell.edu/cfr/text/14/61.51&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(h) Logging training time.&lt;br&gt;&#xA;  (1) A person may log training time when that person receives training from an authorized instructor in an aircraft, flight simulator, or flight training device.&lt;br&gt;&#xA;  (2) The training time must be logged in a logbook and must:&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;(i) Be endorsed in a legible manner by the authorized instructor; and&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;(ii) Include a description of the training given, the length of the training lesson, and the authorized instructor's signature, certificate number, and certificate expiration date.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If I am rated in the aircraft and just getting a local FBOs checkout or familiarization flight with their instructor, must I (also) log it as dual received? Yes I see the word &quot;may&quot; in (h)(1)&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-02-17T17:32:51.213" LastActivityDate="2015-02-17T19:05:17.840" Title="Must I log aircraft checkout flights as dual received?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12736" PostTypeId="2" ParentId="12714" CreationDate="2015-02-17T16:55:50.243" Score="5" Body="&lt;p&gt;You can answer this question empirically. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trim your plane for straight and level flight and set the power to Vy. Look at the AI or visual horizon, and note the pitch attitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now set the power to its Vy climb setting and configure the aircraft (ball, cowl flaps, mixture, prop, etc) to climb configuration, but &lt;strong&gt;don't&lt;/strong&gt; retrim the elevator. Adjust ailerons to maintain straight flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane will pitch up by itself to its Vy climb attitude. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-02-17T16:55:50.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12737" PostTypeId="2" ParentId="12735" CreationDate="2015-02-17T18:23:59.687" Score="3" Body="&lt;p&gt;As the student you are not &lt;em&gt;required&lt;/em&gt; to log training time (because &lt;code&gt;(h)(1)&lt;/code&gt; says &lt;code&gt;may&lt;/code&gt; and not &lt;code&gt;must&lt;/code&gt;). In fact you are not required to log time at all unless you're documenting that time for purposes under 61.51(a) (experience/training required for a rating, a flight review, or for &quot;currency&quot; purposes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no reason &lt;em&gt;not&lt;/em&gt; to log the time as &quot;dual received&quot; however, and if your FBO's insurance requires you to receive a checkout/instructional flight prior to renting that logbook entry is your proof that you &lt;em&gt;received that instruction&lt;/em&gt; from them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are rated for the aircraft in question you may also log the time as Pilot In Command, unless there are other circumstances precluding that (a common one is again insurance requirements).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-17T18:23:59.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12738" PostTypeId="2" ParentId="12707" CreationDate="2015-02-17T18:59:50.430" Score="-6" Body="&lt;p&gt;Flows are basically ways to avoid doing checklists. If you use a checklist you do not need a &quot;flow&quot; because the checklist determines the order of items to be checked so a &quot;flow&quot; is completely superfluous. The &quot;flow&quot; is just a way of checking things ad hoc without using an actual list to save time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason why commercial pilots use &quot;flows&quot; is because if they used a checklist for a lot of activites (which they &lt;em&gt;should&lt;/em&gt; do) it would take too much time. Seriously, do you want 300 people waiting at the gate and leaving 20 minutes late because the pilot is still working through checklist number 7 and making sure the backup oxygen tank is pressurized or whatever? Using &quot;flows&quot; becomes a matter of practicality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where flows become really dangerous is on those private jets where some arrogant CEO is demanding they take off &quot;right now&quot; and the crew starts doing &quot;flows&quot; and skipping checklists. A perfect example is the Gulfstream IV crash last year that killed Lewis Katz, some media mogul, and six other people. The pilot failed to disengage the elevator gust lock. That's the kind of thing that happens when you start doing &quot;flows&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-17T18:59:50.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12739" PostTypeId="2" ParentId="12735" CreationDate="2015-02-17T19:05:17.840" Score="7" Body="&lt;p&gt;Long story short, maybe. The FAA doesn't define &quot;dual time&quot; so it depends how you define it for your own purposes, but in practice most people use it to mean &quot;training time&quot;. There's no definition of &quot;dual&quot; or &quot;dual time&quot; in 14 CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot;&gt;part 1&lt;/a&gt; or &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2&quot;&gt;61&lt;/a&gt; and part 61 never mentions it, apart from a couple of references to &quot;dual instruction&quot;. &quot;Dual&quot; is also not used in &lt;a href=&quot;http://flighttraining.aopa.org/pdfs/faa8710-1.pdf&quot;&gt;form 8710&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But &quot;training received&quot; is clearly defined, and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot;&gt;61.51&lt;/a&gt; says you should log time in general if you need it to satisfy certification or currency requirements:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Training time and aeronautical experience. Each person must&#xA;  document and record the following time in a manner acceptable to the&#xA;  Administrator:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Training and aeronautical experience used to meet the requirements&#xA;  for a certificate, rating, or flight review of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The aeronautical experience required for meeting the recent flight&#xA;  experience requirements of this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So in your example, do you need to log the time for a) certification/currency purposes, and/or b) as training received? And if you do log it, is it &quot;dual&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For certification/currency, it's usually best to log everything: even if you don't need to show the FAA something, your insurance company or FBO might ask you for details of your flying time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for training, in order for a flight to be &quot;training received&quot;, the instructor has to endorse your logbook:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) The training time must be logged in a logbook and must:   (i) Be&#xA;  endorsed in a legible manner by the authorized instructor; and   (ii)&#xA;  Include a description of the training given, the length of the&#xA;  training lesson, and the authorized instructor's signature,&#xA;  certificate number, and certificate expiration date.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's a simpler case: if the instructor didn't sign your logbook then you didn't receive training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But let's say that you decide to log the flight for one or both of the reasons above. Is it &quot;dual&quot;? Well, since there's no official definition of &quot;dual&quot; then it depends what &lt;em&gt;you&lt;/em&gt; use it to mean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, practically speaking, most people use &quot;dual&quot; to mean &quot;training&quot;: my &lt;a href=&quot;http://myflightbook.com&quot;&gt;logging software&lt;/a&gt; uses it that way, and many paper logbooks seem to as well. So I only log dual if I have a corresponding endorsement from my instructor. (The software also has options like &quot;instructor on board&quot; or &quot;introductory flight&quot; that I can use for the scenarios you described.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a specific example, I did an FBO checkout ride in a new aircraft type a few months ago. I was already rated for the aircraft category/class and the instructor with me didn't endorse my logbook, he just updated the FBO's internal documentation to state that I'm now allowed to rent it. So I logged the time as PIC, but not dual.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-17T19:05:17.840" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12741" PostTypeId="1" CreationDate="2015-02-17T20:07:38.523" Score="4" ViewCount="1550" Body="&lt;p&gt;This question is not about aviation itself, but rather about job opportunities in aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It kind of goes into law a little, maybe somebody has some experience with this issue though:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being from Germany, I'd like to become a FAA CFI. This itself is not a huge problem, but working as a CFI in the US is one, as I would need a citizenship or a green card to work there... or would I not?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anybody know anyone who is a CFI or works as a pilot in the US and is not a US-citizen?&#xA;Or does anybody have an idea of how to work as a CFI without a green card or citizenship?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing this isn't pure aviation, this still appears to me as one of the best places to ask, you all know that experience can not be out ruled!&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="39" LastEditDate="2015-04-17T19:52:07.407" LastActivityDate="2015-04-17T19:52:07.407" Title="Becoming a CFI in the USA as a non-US citizen" Tags="&lt;faa-regulations&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-02-17T21:49:35.583" ContentLicense="CC BY-SA 3.0" />
  <row Id="12742" PostTypeId="1" AcceptedAnswerId="12743" CreationDate="2015-02-17T20:26:31.617" Score="17" ViewCount="2079" Body="&lt;p&gt;As suggested by a user in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-climb-nose-up-must-lift-increase-to-climb&quot;&gt;this&lt;/a&gt; question, I'd like to ask this question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most basic aerobatic maneuvers is a vertical climb. This can be achieved by just pitching up to what appears to be 90°. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming it is really a 90° pitch up maneuver, wouldn't the lift of the wing (though smaller due to less speed) and the missing gravity to counteract the lift make the plane go &quot;up&quot; (again, planes point of view!)?&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2017-04-12T14:47:58.303" Title="Why do planes not fly &quot;backwards&quot; (up from the planes POV) when in a vertical climb?" Tags="&lt;aerobatics&gt;&lt;lift&gt;&lt;climb&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12743" PostTypeId="2" ParentId="12742" CreationDate="2015-02-17T20:44:44.193" Score="13" Body="&lt;p&gt;Short answer: Yes. But only for a moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you suggest, let's focus on the 90° case, because many things will become simpler. Intermediate climb angles can be covered by a linear superposition of horizontal and vertical flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we shoot up at 90° flight path angle (engine thrust permitting) and leave some angle of attack for the wing to create lift. Lift acts orthogonally to the local flow direction, so the lift will pull the aircraft sideways (up in the aircraft's frame of reference). Since there is no other force which will oppose this lift (drag, weight and thrust all act at 90° to the lift, parallel to the flight path), the aircraft will accelerate sideways (again, up in the aircraft's frame of reference). The angle of attack will immediately decrease and lift creation will stop &amp;mdash; or the pilot forces the angle of attack to stay constant by pulling the elevator, and now the aircraft will further increase its flight path angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is a complicated way of saying that the pilot forces the airplane into a loop. If he wants to maintain this 90° flight path angle, he better avoid creating any lift.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="4474" LastEditDate="2015-05-19T18:15:22.953" LastActivityDate="2015-05-19T18:15:22.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12744" PostTypeId="2" ParentId="12741" CreationDate="2015-02-17T20:49:11.980" Score="4" Body="&lt;p&gt;You do not need to be a citizen to be a U.S. CFI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to have US ratings, so you would have to have all your German licenses/ratings converted, which takes some time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have to be absolutely FLUENT in both spoken and written English.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to charge students money for your services, you have to have US residency or other work visa authorization. You do not need a work visa if you train students for free.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-17T20:49:11.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12746" PostTypeId="1" CreationDate="2015-02-17T21:28:21.923" Score="2" ViewCount="2475" Body="&lt;p&gt;On commercial flights there are some &quot;typical&quot; security checks - metal detectors, luggage X-rays, etc. - are there similar security checks if you're flying in your own private plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there different or additional security checks when flying into other countries (such as a trip from Canada to the United States)?&lt;/p&gt;&#xA;" OwnerUserId="7347" LastEditorUserId="64" LastEditDate="2015-02-18T03:44:59.407" LastActivityDate="2015-02-18T03:45:28.767" Title="Are there security checks on private flights in your own plane?" Tags="&lt;general-aviation&gt;&lt;security&gt;&lt;international&gt;" AnswerCount="3" CommentCount="2" ClosedDate="2015-02-18T03:45:39.140" ContentLicense="CC BY-SA 3.0" />
  <row Id="12747" PostTypeId="1" AcceptedAnswerId="12750" CreationDate="2015-02-17T22:01:28.227" Score="16" ViewCount="46112" Body="&lt;p&gt;I know that before you even begin training in flight school, you are required to get a physical examination from a doctor to determine if you are fit to fly. Online articles stressed the importance of being completely honest with the doctor about any existing conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was just recently diagnosed with ADD (or rather, I described my issues to my regular physician and simply started receiving medication to treat it) and this is something I would naturally disclose at the physical examination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does FAA disqualify someone from getting their pilot's license on the basis of ADD?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I take medication for this once a day and it resolves any issues I face from it.&lt;/p&gt;&#xA;" OwnerUserId="7348" LastEditorUserId="5517" LastEditDate="2015-11-18T17:30:49.507" LastActivityDate="2021-01-09T19:17:03.637" Title="Can I become a pilot if I am under treatment for Attention Deficit Disorder?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;medical&gt;" AnswerCount="5" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12748" PostTypeId="2" ParentId="12445" CreationDate="2015-02-17T22:23:16.647" Score="4" Body="&lt;p&gt;For US (N-reg aircraft), this is defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1703&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.703&lt;/a&gt;, &lt;em&gt;Operations of civil aircraft of U.S. registry outside of the United States&lt;/em&gt;. It says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Each person operating a civil aircraft of U.S. registry outside of&#xA;  the United States shall—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) When over the high seas, comply with annex 2 (Rules of the Air) to&#xA;  the Convention on International Civil Aviation and with §§91.117(c),&#xA;  91.127, 91.129, and 91.131;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) When within a foreign country, comply with the regulations&#xA;  relating to the flight and maneuver of aircraft there in force;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Except for §§91.117(a), 91.307(b), 91.309, 91.323, and 91.711,&#xA;  comply with this part so far as it is not inconsistent with applicable&#xA;  regulations of the foreign country where the aircraft is operated or&#xA;  annex 2 of the Convention on International Civil Aviation; [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That suggests that in most cases the pilot should follow the foreign (Italian) regulations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;91.703(a)(2) says you have to follow foreign regulations on &quot;flight and maneuver&quot;&lt;/li&gt;&#xA;&lt;li&gt;703(a)(3) says you should (mostly) follow part 91 unless it's &quot;inconsistent&quot; with the foreign regulations &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It all seems a bit vague to me, and what &quot;inconsistent&quot; means is probably the kind of thing that keeps lawyers busy. But also note that there are specific rules applying to operating foreign aircraft in the US. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1711&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.711&lt;/a&gt;, &lt;em&gt;Special rules for foreign civil aircraft&lt;/em&gt;, begins:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) General. In addition to the other applicable regulations of this&#xA;  part, each person operating a foreign civil aircraft within the United&#xA;  States shall comply with this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So foreign aircraft in the US are expected to follow US regulations as far as possible, which is consistent with 91.703: an N-reg aircraft abroad follows the foreign rules as far as possible, and a foreign aircraft in the US follows US rules as far as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since both the US and Italy are &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization#Membership&quot; rel=&quot;nofollow&quot;&gt;ICAO members&lt;/a&gt;, I would expect Italian law to roughly mirror US law on this, although that may be a dangerous assumption. For an authoritative answer, I would ask both the FAA and the &lt;a href=&quot;http://www.enac.gov.it/servizio/info_in_english/&quot; rel=&quot;nofollow&quot;&gt;Italian authorities&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-17T22:23:16.647" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12749" PostTypeId="2" ParentId="12746" CreationDate="2015-02-17T22:29:47.630" Score="1" Body="&lt;p&gt;Depends on the pilot. If I know one of my passengers well, I'm not security checking them, other than a reminder about dangerous goods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I don't know one of my passengers, then I'm doing a verbal confirmation that they don't have anything on board that I don't want on board, and if they're at all shifty, I'm checking more thoroughly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't own an x-ray machine.&lt;/p&gt;&#xA;" OwnerUserId="7324" LastActivityDate="2015-02-17T22:29:47.630" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12750" PostTypeId="2" ParentId="12747" CreationDate="2015-02-17T22:37:00.757" Score="16" Body="&lt;p&gt;I'm going to assume you're asking about US/FAA requirements - If not what's below may not be particularly helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADD is not a disqualifying condition, however if you have a formal diagnosis of ADD or ADHD &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/dec_cons/disease_prot/adhd/&quot;&gt;you may need to undergo additional testing&lt;/a&gt; in order to receive a medical certificate.&#xA;Also some of the medications used to treat ADD/ADHD may be disqualifying (I know that Adderall, Focalin, and Ritalin were all on the FAA's &quot;No Fly&quot; list - I'm not sure if they're still an absolute NO or if you can get approval for them).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA has &lt;a href=&quot;http://www.aopa.org/members/databases/medical/search_faa_meds.cfm?action=search&quot;&gt;a pretty decent drug list&lt;/a&gt; that you can search to see if what you've been prescribed is permitted - it's a little easier to search/cross-reference than &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/pharm/dni_dnf/&quot;&gt;the official FAA &quot;Do Not Issue/Do Not Fly&quot; list&lt;/a&gt; and they do a good job keeping it up to date, and &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Mental-Health/ADD-and-ADHD&quot;&gt;a brief article on ADD/ADHD &amp;amp; medical certification&lt;/a&gt;.&lt;br&gt;&#xA;They also have a service to assist you with getting your medical (as part of &lt;a href=&quot;http://pilot-protection-services.aopa.org/PPS-Plan-Details&quot;&gt;Pilot Protection Services&lt;/a&gt;) which can be helpful.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-02-18T03:06:20.343" LastActivityDate="2015-02-18T03:06:20.343" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12751" PostTypeId="2" ParentId="12746" CreationDate="2015-02-17T22:37:31.627" Score="2" Body="&lt;p&gt;No, at least not at the Class C and D airports I have been to. There is just a locked gate with an attendant who makes sure you are either flight crew or are boarding a flight. This is to prevent the possibility of a random person walking around on the ramp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PIC of the aircraft, of course, may question you (&quot;your hunting rifle is unloaded, right?&quot;) or may search your bags or body cavities or whatever he wants to do before he will let you get on. It depends on the situation. For a charter flight normally they will just verbally talk to you to make sure you aren't unknowingly bringing anything dangerous aboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you fly into a country from a different country, everybody has to go through customs. So, what happens is that you all wait around in the lobby of the GA terminal while some dude from the airport examines your customs forms and goes through your luggage. Sometimes they will search the whole plane too if they want to be dicks. In smaller airports, like in a Caribbean island, you will be routed through the same customs lines that commercial passengers use.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-17T22:37:31.627" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12752" PostTypeId="2" ParentId="12742" CreationDate="2015-02-17T22:38:46.323" Score="3" Body="&lt;p&gt;Answering your question, what will happen with the list depends on what maneuver the pilot is trying to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the situation you are describing and taking the picture that &lt;a href=&quot;https://aviation.stackexchange.com/a/12720&quot;&gt;@PeterKämpf&lt;/a&gt; prepared:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7vD23.png&quot; alt=&quot;Airplane force diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your situation the gamma angle is 90º, so basically the gravity (mg) will be aligned with drag and thrust (T) will be used to compensate both weight (mg) and drag (D). Acceleration of the airplane will be T-mg-D = ma (our friend Newton). Actually, in a typical airplane, drag will be negligible compared to weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this situation, there is one variable missing, the angle of attack (alpha).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's go to the maneuver...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) I would like to have my airplane stopped in the air. In this situation you try to keep the airplane at 0 speed so you don't have any lift. I have seen this done for a few seconds (or less than one) by a Typhoon in an airshow (was about 70-80º actually). It was really difficult for the pilot to keep it stable, it was moving a little bit normal to the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) You would like to have an stable climbing totally vertical. First thing is that this is not the most efficient way to do it as it is not something normal in operation. Will be the same situation as before, but there will be some speed, the pilot will try to keep the angle of attack stable to produce no lift. Problem is that such angle of attack varies with speed... so he will struggle. The Typhoon made that to scape back from the situation... he moved up and pitched down. Also climbing intercept mission in combat airplane is close to this one still very extreme.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) You are making a loop. You create some lift to make it possible so the airplane is turning. That's better explained by &lt;a href=&quot;https://aviation.stackexchange.com/a/12720&quot;&gt;@PeterKämpf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a general comment those maneuver are usually performed in airshow by airplanes prepared for this and I have never seen any &quot;pure&quot; situation of what you are describing, just situations very close to what you describe. Neither combat airplanes are using it regularly although might have the capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However those operations are not affordable by civil airplanes. Usually thurst compensates drag and lift weight, usually lift is of the order of 10 times bigger than drag, so basically engine thrust capability is around tenth of the weight (if you consider extreme operations you will end up with a number of 2-3 times smaller). Just take the example of &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320&lt;/a&gt;, A318 OEW is aroudn 40Tons and the thrust is 210KN (weight is twice the maximum) and going to MTWO we have 68tons (3 times).&#xA;(remember the g on previous calculation)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So... normal planes usually don't have a big engine compared to their weight, however the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Typhoon&lt;/a&gt; has a ratio of 1.15 thrust/weight.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-02-18T01:34:50.240" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12753" PostTypeId="1" AcceptedAnswerId="12974" CreationDate="2015-02-17T23:15:53.447" Score="10" ViewCount="5973" Body="&lt;p&gt;The only recent engine using GTF technology is the PW1000G, however some old designs like ALF502 or TFE731 use this technology. I understand the basic concept of the benefit obtained by the engine introducing this technology (basically giving another parameter to optimize RPMs at low pressure turbine and fan) and that benefit is compensated by the increase in weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is blocking this technology to be further included in modern turbofans? Is it only a business case for P&amp;amp;W architecture?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What made it possible in PW1000G that blocked PW8000?&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="1696" LastEditDate="2015-02-17T23:27:06.000" LastActivityDate="2018-04-15T21:30:43.530" Title="What are the limitations in adoptions of GTF (Geared Turbofan) technology?" Tags="&lt;engine&gt;&lt;turbofan&gt;&lt;geared-turbofan&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12754" PostTypeId="5" CreationDate="2015-02-17T23:24:20.537" Score="0" Body="&lt;p&gt;The &lt;em&gt;turbofan&lt;/em&gt; is an extremely common type of &lt;a href=&quot;/questions/tagged/jet-engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet-engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet-engine&lt;/a&gt;, derived from the earlier, more primitive &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt;.  Although the concept of a turbofan dates back almost as far as that of a turbojet, the first turbofan engine (the Rolls-Royce Conway, iteration &lt;em&gt;RCo.2&lt;/em&gt;) did not run until July 1952, as jet engine development during World War II had concentrated on turbojets in order to get a jet into the air as soon as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The core of a turbofan is very similar to a turbojet; however, a turbofan's core has one or more additional turbine stages after those driving the compressor.  These additional turbine stages drive a large fan or fans, which blow additional air (known as &lt;em&gt;bypass air&lt;/em&gt;) around the engine core, providing additional thrust.  The fan(s) are usually located at the very front of the engine, ahead of the compressors, although a few turbofans (such as General Electric's CJ805-23 and CF700) instead used fans located at the &lt;em&gt;back&lt;/em&gt; of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One important measure of a turbofan is its &lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt;, the ratio between the amount of bypass air passing through the engine and the amount of air that enters the engine's core (for instance, a turbofan that blows 10 tonnes of air through its bypass duct in 1 second and draws only half a tonne through the engine core in that same time period would have a bypass ratio of 20:1).  Turbofans are classified into two main categories, based on their bypass ratio:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;em&gt;Low-bypass turbofans&lt;/em&gt; have a bypass ratio of less than 5:1, and usually generate most of their thrust from the core air.  All early turbofans were low-bypass, and some smaller narrowbody (single-aisle) jetliners continued to use low-bypass turbofans (principally the popular Pratt &amp;amp; Whitney JT8D) well into the 1990s; they remain common on combat aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;High-bypass turbofans&lt;/em&gt; have a bypass ratio of 5:1 or greater, and usually generate most of their thrust from their bypass air.  The earliest high-bypass turbofan (the General Electric TF39, bypass ratio 8:1) first ran in 1965, and entered service in 1968 aboard &lt;a href=&quot;/questions/tagged/lockheed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lockheed&amp;#39;&quot; rel=&quot;tag&quot;&gt;lockheed&lt;/a&gt;'s C-5 Galaxy military transport. &#xA;Large high-bypass turbofans (being far more powerful and efficient than their low-bypass cousins) were almost immediately appropriated for use on the widebody (twin-aisle) jetliners then under development; the &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt;, which first flew in February 1969 and entered service the following January, was not only the first widebody airliner, but also the first airliner powered by a high-bypass turbofan (the Pratt &amp;amp; Whitney JT9D).  All newer jetliners use high-bypass turbofans, as do most large military transports (midsize and smaller transports instead use &lt;a href=&quot;/questions/tagged/turboprop&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turboprop&amp;#39;&quot; rel=&quot;tag&quot;&gt;turboprop&lt;/a&gt; engines).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;As the bypass air of a turbofan is colder and slower-moving than the core air, it is more efficient at generating thrust at relatively low speeds than the core air (or the exhaust of a turbojet) is; this effect is stronger for high-bypass turbofans, due to their greater amount of bypass air.  As such, high-bypass turbofans are the most efficient aircraft engines at speeds between approximately mach 0.65 (below this speed, turboprops and piston engines are more efficient) and mach 1, while low-bypass turbofans are the best choice for the mach 1 - mach 2 range (above which they are, in turn, surpassed by turbojets); civilian jetliners and large military transports, which generally cruise in the former speed range, use high-bypass turbofans, while combat aircraft (which place more emphasis on the ability to go &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; if need be, although not as much as they used to) are powered by low-bypass turbofans.  At &lt;a href=&quot;/questions/tagged/subsonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;subsonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;subsonic&lt;/a&gt; speeds, a turbofan's efficiency can be increased essentially without limit by increasing its bypass ratio (as long as the engine core is powerful enough to drive such a large fan).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The large amount of (relatively) cold, slow-moving air shrouding the core exhaust also reduces the amount of noise generated by turbofans, with the result that even low-bypass turbofans are many times quieter than turbojets, and high-bypass turbofans are quieter still.  A turbofan's noise level can be decreased even further by equipping it with a nozzle that mixes bypass air into the core exhaust stream; early turbofan jetliners commonly used highly-distinctive scalloped nozzles which forced the core and bypass air into intertwined streams.  When the first high-bypass turbofans came about, they were seen (or, rather, heard) as enough quieter on their own to not need exhaust-mixing nozzles. &#xA; However, since then, aircraft noise restrictions have gotten much stricter, and many jetliners now use various methods of exhaust mixing; some (such as the &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;'s GE/SNECMA CFM56s) simply enclose the entire engine with a long shared cowling, allowing the turbulence at the boundary between the core and bypass flows to mix them to some extent, while others (for example, the &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;'s GE GEnxes) give the core tailpipe a sawtoothed rear edge which creates turbulence at the boundary between the core and bypass flows and encourages mixing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see the Wikipedia articles about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Turbofan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turbofans&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Bypass_ratio&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bypass ratio&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Exhaust_mixer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Exhaust mixers&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-02-07T05:32:45.010" LastActivityDate="2019-02-07T05:32:45.010" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12755" PostTypeId="4" CreationDate="2015-02-17T23:24:20.537" Score="0" Body="A type of jet engine which uses two different airflow streams (one passing through the core and another blown past it by a fan) for obtaining thrust." OwnerUserId="6979" LastEditorUserId="22726" LastEditDate="2020-04-26T01:31:59.330" LastActivityDate="2020-04-26T01:31:59.330" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12756" PostTypeId="5" CreationDate="2015-02-17T23:26:09.553" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-02-17T23:26:09.553" LastActivityDate="2015-02-17T23:26:09.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12757" PostTypeId="4" CreationDate="2015-02-17T23:26:09.553" Score="0" Body="Is a kind of turbofan that uses a reduction gearbox between the low pressure shaft and the fan." OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2015-02-18T03:49:39.357" LastActivityDate="2015-02-18T03:49:39.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12758" PostTypeId="2" ParentId="12746" CreationDate="2015-02-18T00:00:46.650" Score="1" Body="&lt;p&gt;I worked at a general aviation airport in Canada for 10 years. Security consisted of 3 strands of barbed wire and a padlock on the gate. Security checks before boarding anyone consisted of whatever you wanted to do, including nothing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying to the States simply required that the first landing be at any airport with Customs and Immigration.&lt;/p&gt;&#xA;" OwnerUserId="2590" LastActivityDate="2015-02-18T00:00:46.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12759" PostTypeId="2" ParentId="3421" CreationDate="2015-02-18T00:53:18.847" Score="2" Body="&lt;p&gt;Mixing things in with aviation fuels that aren't purpose-engineered for the aircraft fuel system environment is useless at best and harmful to the airplane and/or engine at worst.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of your list:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mycotoxins, blood-based stuff, and spores would simply burn up.&lt;/li&gt;&#xA;&lt;li&gt;Live biologicals are worse -- they can cause &lt;a href=&quot;http://nzetc.victoria.ac.nz/tm/scholarly/tei-Bio19Tuat01-t1-body-d4.html&quot; rel=&quot;nofollow&quot;&gt;trouble&lt;/a&gt; even before they get the chance to burn up.  For instance, they can produce corrosive organic acids, gnaw on plastic and rubber parts, or form biofilms and mats that work wonders for clogging orifices.  Also, &lt;a href=&quot;http://en.wikipedia.org/wiki/Fuel_system_icing_inhibitor&quot; rel=&quot;nofollow&quot;&gt;fuel system icing inhibitors&lt;/a&gt; have biocidal effects as they deprive any would-be-living-things in the fuel of much-needed water.&lt;/li&gt;&#xA;&lt;li&gt;Metals have an annoying habit of catalyzing reactions that form gummy deposits in fuel system parts; in fact, &lt;a href=&quot;http://en.wikipedia.org/wiki/Metal_deactivator&quot; rel=&quot;nofollow&quot;&gt;additives&lt;/a&gt; are used to get metal ions in the fuel into a sequestered state where they won't cause gummy, gunky trouble.  Civil Jet-A doesn't use them as often because refiner QC and QA are better  than they were about keeping metal ions out of the fuel to begin with, but they are a key ingredient in the +100TS &lt;a href=&quot;http://en.wikipedia.org/wiki/JP-8#Variants&quot; rel=&quot;nofollow&quot;&gt;additive package&lt;/a&gt; used in military JP-8.&lt;/li&gt;&#xA;&lt;li&gt;Particulate additives are a particularly bad choice as they have the strong potential to clog orifices and jam fine moving parts in aircraft fuel system control elements, which can have &lt;a href=&quot;http://avherald.com/h?article=42a1000b/0003&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;serious&lt;/a&gt; to catastrophic consequences.  This rules out polymer fibers and coated fiberglass.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As a sidenote -- ethylene dibromide is only used in aviation gasoline, which is a niche fuel in the current commercial aviation world (some Part 135 operators use it, but that's really about it -- turbine reliability is too convincing an argument to avoid for all but the smallest aircraft used in even air taxi and commuter airline service).  Considering the airplanes that burn it, it can be scratched off the list fairly safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In conclusion: anyone who tried to &quot;spike&quot; some Jet-A with a sooper sekret mystery additive would do nothing useful at best, and wind up getting blamed for a smoking hole in the ground at worst.  Imagine being the CIA and having the NTSB trying to roast you over a top secret program...&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-02-18T00:53:18.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12761" PostTypeId="1" CreationDate="2015-02-18T02:59:21.523" Score="8" ViewCount="565" Body="&lt;p&gt;Consider a Boeing 737 cruising over the Atlantic when an engine flames out. The procedure here is clear: the pilot flying should continue flying the plane, while the pilot not flying should pull out the QRH and follow the checklist for engine flameout. What happens, though, if the pilot not flying is engaging in Flight Crew In-Seat Rest? I assume they're woken up, and then I see a few options:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;the pilot flying continues to fly while the pilot not flying wakes up and overcomes their sleep inertia. After 20 minutes, they go through the engine out checklist&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the pilot flying continues to fly while the pilot not flying immediately goes through the engine out checklist, despite the risk of sleep inertia&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the pilot not flying immediately starts flying despite the risk of sleep inertia, and the pilot flying goes through the engine out checklist&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the pilot flying flies the plane while going through the checklist as the pilot not flying wakes up&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These all sound like awful options. So  what would actually happen in such a situation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/q/12212/3170&quot;&gt;Is a pilot allowed to sleep during a flight?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-02-18T11:19:48.683" Title="How are emergencies handled during In-Seat Rest?" Tags="&lt;safety&gt;&lt;emergency&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12762" PostTypeId="1" CreationDate="2015-02-18T03:43:12.560" Score="15" ViewCount="5648" Body="&lt;p&gt;I took this photo when I saw a plane make a crazy 90 degree turn. What kind of aircraft could do this? I have a plane finder app for commercial aircraft and this plane did not show, which is the first time that's happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4WxGb.jpg&quot; alt=&quot;plane making sharp turn&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7351" LastEditorUserId="6919" LastEditDate="2015-02-18T04:37:35.970" LastActivityDate="2018-05-11T15:50:16.283" Title="What aircraft can make these sharp 90-degree turns?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12763" PostTypeId="2" ParentId="170" CreationDate="2015-02-18T04:45:36.847" Score="14" Body="&lt;p&gt;There are definitely some standard warning signs you can look for:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Any &lt;em&gt;colored&lt;/em&gt; fluid or oil-like substance dripping from the wing.&lt;/li&gt;&#xA;&lt;li&gt;Any sign of buckling or irregular bends in the skin of the aircraft or popped rivets&lt;/li&gt;&#xA;&lt;li&gt;Fire, smoke or the smell of something burning&lt;/li&gt;&#xA;&lt;li&gt;Loose or missing panels or farings&lt;/li&gt;&#xA;&lt;li&gt;Presence of a red streamer or anything that says &quot;REMOVE BEFORE FLIGHT&quot;&lt;/li&gt;&#xA;&lt;li&gt;When a door is closed and secure for flight it should have an orange strip diagonally across the window; if the strip is hanging straight down, something has gone wrong.&lt;/li&gt;&#xA;&lt;li&gt;Any member of the flight crew that appears drunk, woozy or disoriented&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="65" LastEditDate="2015-02-18T15:23:16.000" LastActivityDate="2015-02-18T15:23:16.000" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12764" PostTypeId="1" AcceptedAnswerId="12768" CreationDate="2015-02-18T06:09:24.777" Score="3" ViewCount="2741" Body="&lt;p&gt;Is there a list of medications which would disqualify a pilot from flying or obtaining a Class 1 medical?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prior to having my medical I want to know if any medication I am likely to take will disqualify me, so that I can make enquiries about switching to an approved alternative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A link to a list of prohibited or otherwise troublesome medications or similar online resource would be ideal.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="167" LastEditDate="2015-02-18T13:45:26.827" LastActivityDate="2015-02-18T13:45:26.827" Title="Is there a list of CASA prohibited medications which would disqualify a pilot from flying or obtaining a Class 1 medical?" Tags="&lt;medical&gt;&lt;casa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12765" PostTypeId="2" ParentId="12724" CreationDate="2015-02-18T07:11:31.103" Score="17" Body="&lt;p&gt;I echo @Pondlife's answer - base your response on the severity, and if in any doubt loop in AOPA legal. If you do nothing else, file a NASA ASRS form; it's not a guarantee but it can do no harm. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a student pilot 15 years ago, I got The Number during an early solo at Paine Field (KPAE) near Seattle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I received taxi instructions to 34L at A4, did my runup, and called Tower requesting closed pattern, 34L. I was cleared for takeoff, runway 34R. On the upwind, Tower asked me to switch to 132.95... the west-side Tower frequency. Oops. Then they asked me to write down The Number. I finished my landings, because you gotta get back on the horse, then landed, told my instructor, and we called.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By that time the manager had pulled the tapes and determined that, yes, I missed the runway identifier, but the controller also didn't catch that I said I was at a 34L intersection. Everybody was both at fault and not really at fault. Apparently another plane on long final went around, but it wasn't anything crazy dangerous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that resulted from the incident was, about two weeks later, the appearance of signs reading &quot;TOWER 132.95&quot; and &quot;TOWER 120.2&quot; at the appropriate intersections. They're still there today! :)&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-02-18T07:11:31.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12766" PostTypeId="2" ParentId="12762" CreationDate="2015-02-18T08:19:16.520" Score="8" Body="&lt;p&gt;We looked at how tight a turn a Boeing 747 can make in &lt;a href=&quot;https://aviation.stackexchange.com/questions/8012/what-does-it-take-to-turn-a-747-around-180-degrees&quot;&gt;this question&lt;/a&gt;. The answer gave a radius of just 6.11 km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your contrail photo clearly shows that the airplane has either one or two fuselage-mounted engines. The 747 was assumed to have a limit of 1.5g for the 6 km turn, but if the aircraft in your photo has a higher buffet and airframe limit, much tighter turns would be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turn radius $R$ can be determined when airspeed $v$ and bank angle $\Phi$ rsp. load factor $n_z$ are known: $$R = \frac{v^2}{g\cdot tan\Phi} = \frac{v^2}{g\cdot \sqrt{n_z^2-1}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your airplane was traveling at Mach 0.7 in FL300, its speed would have been 212 m/s. Let's further assume it could pull 3g at this speed and altitude, and your turn radius becomes 1.624 km or just about one mile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is very hard to judge the radius of the contrail's turn section, but it is quite easy to list the characteristics which help to make the radius small:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Low wing loading&lt;/li&gt;&#xA;&lt;li&gt;enough thrust to sustain high load factors&lt;/li&gt;&#xA;&lt;li&gt;enough strength to allow for high load factors&lt;/li&gt;&#xA;&lt;li&gt;enough lift capability to allow for high load factors&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One could add the capacity to fly high enough to be able to form contrails, but this is already implicitly contained in the other conditions. We need something with big wings and a powerful engine - a lightly loaded fighter aircraft in other words.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-18T08:19:16.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12767" PostTypeId="2" ParentId="170" CreationDate="2015-02-18T08:29:59.717" Score="6" Body="&lt;p&gt;Here is some personal experience, though not as spectacular as the other pictures shown here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ixljl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was on a flight from Chicago to Paris CDG, when I noticed somewhere near Spain that there's a loose plate on top of this stabilizer / rear part of pylon of the A340. Being at home, I saw that it was already there at takeoff, as you can see on my picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quite interesting part is that after touchdown, when all air brakes were activated, the plate started to flutter extremely due to the turbulent air flow. At a certain speed, the lift of the air flow was so low, that the plate sunk down into its designated position, and it was as if there has never been something wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I told the cabin crew and got an audience with the pilot. It was difficult to explain the problem to him, as &lt;em&gt;it was not visible any more&lt;/em&gt;. He also doubted that I may have seen the flaps...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However... I think this was no serious problem for the aircraft itself, but parts falling off an aircraft on the runway can be a bad thing. Especially at Paris Charles de Gaulle, our destination, they had some very disastrous experience with it.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="19" LastEditDate="2015-02-18T16:40:15.420" LastActivityDate="2015-02-18T16:40:15.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12768" PostTypeId="2" ParentId="12764" CreationDate="2015-02-18T08:34:52.763" Score="3" Body="&lt;p&gt;There is no all-encompassing list of 'banned' medications publically available for Australia. In the regulations there is a 'catch all' to the effect of &quot;pilots must not take any medications which may inhibit their ability to fly safely&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want specific advice on a specific medication, why not give CASA a call? That or you can see a DAME (which is a GP qualified to do aviation medical assessments).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you can find out there is &lt;em&gt;general advice&lt;/em&gt; though. Although questions such as &lt;a href=&quot;https://aviation.stackexchange.com/questions/12747/can-you-get-a-pilots-license-while-taking-medication-for-add-attention-deficit?rq=1&quot;&gt;this on ADHD&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1320/what-medications-may-pilots-take-while-flying?rq=1&quot;&gt;this more generally&lt;/a&gt; refer to the US system, the Australian restrictions are not too dissimilar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Broardly speaking, Ritalin and other 'depressants' are incompatible with flying. Bi-polar disorder faces many restrictions but stable depression is manageable. I did hear somewhere that you need to be off antidepressants for 12 months though. Diabetes and blood thinning medications are OK but subject to regular testing and scrutiny. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside, sometimes CASA, instead of outright refusing the medical, will place restrictions on it instead. This can be things like you must fly by day VFR only, or you can only fly with a qualified pilot next to you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: I found &lt;a href=&quot;http://casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_102333&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page from the CASA website&lt;/a&gt; which has a list of medications to stay away from. It's not exhaustive but it's a start&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-02-18T10:12:39.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12769" PostTypeId="2" ParentId="12762" CreationDate="2015-02-18T08:39:22.953" Score="4" Body="&lt;p&gt;As we do not know which airplane were you observing and neither the airspace it was moving in, one possibility, aside for military aircrafts, it could be that it was an acrobatic one, maybe training on specific maneuvers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vtUXg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a turn from a long distance could look like it is seen in the photo you posted.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-02-18T08:39:22.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12770" PostTypeId="1" CreationDate="2015-02-18T09:21:23.810" Score="5" ViewCount="1981" Body="&lt;p&gt;Can X-Plane be used as an actual Flight and Navigation Procedures Trainer (FNPT) level 1 flight simulator with Out The Window (OTW) visuals, separate Instructor Operation Station (IOS) and replica hardware?&lt;/p&gt;&#xA;" OwnerUserId="7353" LastEditorUserId="1467" LastEditDate="2015-02-18T16:24:14.543" LastActivityDate="2017-04-28T04:00:12.660" Title="Can X-Plane be used as a professional simulator?" Tags="&lt;flight-training&gt;&lt;easa-regulations&gt;&lt;flight-simulator&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12773" PostTypeId="2" ParentId="12761" CreationDate="2015-02-18T11:19:48.683" Score="10" Body="&lt;p&gt;Option 2:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the pilot flying continues to fly while the pilot not flying&#xA;  immediately goes through the engine out checklist, despite the risk of&#xA;  sleep inertia.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When waking up to an emergency situation your body will start to produce adrenaline which gets you over the sleep inertia very quickly. If the situation is not clear to the PNF, he will be briefed by the PF. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides that, in a checklist flow, both pilots are involved and crosscheck each other's actions.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-02-18T11:19:48.683" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12774" PostTypeId="2" ParentId="12634" CreationDate="2015-02-18T16:17:27.043" Score="2" Body="&lt;p&gt;Flight simulators are great for learning systems and procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have good quality controls (professional-quality yoke, pedals, and throttle), then you can even learn complex procedures, such as instrument flying using a simulator like X-Plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, that said, flight simulators are not realistic depictions of actual flight. For example, in real flight in a small aircraft you frequently get bumped by gusts and have to constantly be doing small corrections. A simulator flies very smooth and completely lacks this reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise, in real flight the air is constantly challenging you on a windy day. You will be on short final and get sink or gusts that will knock you off your line and you have to INSTANTANEOUSLY react and adjust correctly or you will end up having to do a go around. It can be very chaotic, especially anywhere there are hills or mountains and air is bouncing around. Once again a simulator just does not capture this at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find landing in simulators to be completely unrealistic. Since this is by far the hardest part of flying, simulators cannot really teach you at the real level. In a simulator you just get the aircraft near the ground going the right speed and, boom, you land, easy. In the real world this does not happen at all. In the real world, keeping the aircraft level, lined up and flaring in the presence of any kind of cross wind is very tricky. Go to a small airport and watch a student landing sometime. They balloon, land on one wheel and go screeching across runway, drop the nose hard, etc. It's a mess. A beginner without an instructor will be a large risk of ground looping. The simulator completely eliminates all these problems.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-18T16:17:27.043" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12775" PostTypeId="1" AcceptedAnswerId="12777" CreationDate="2015-02-18T16:26:51.490" Score="21" ViewCount="5736" Body="&lt;p&gt;Helicopters use a cyclic control to tilt each blade differently through the rotor's revolution. This is quite a complex mechanism. What is the advantage of this vs tilting the whole rotor plane? This seems to be a much more simple solution.&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="572" LastEditDate="2015-02-19T11:45:48.107" LastActivityDate="2019-07-29T17:27:09.740" Title="Why does a helicopter need cyclic control rather than just tilting the whole main rotor?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12776" PostTypeId="1" CreationDate="2015-02-18T16:36:35.697" Score="12" ViewCount="3743" Body="&lt;p&gt;I was recently on a flight during which a passenger had a medical emergency.  The passenger vomited and was reportedly unconscious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft was either a Boeing 737-700 or 737-800.  I'm pretty sure it was the 800.  It had pretty blue lighting on the interior ceiling, including oval illuminated cutaways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Located above one row of seats were two ports marked &quot;Medical Communications&quot; (or something like that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the emergency, one of the flight attendants connected a wired headset to these ports in order to communicate with others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With whom was he likely speaking?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;As an aside, the system was poorly designed.  One ports was black and the other gray; both ports otherwise looked identical and were the same size; the colors of the headphone connectors did not match the ports.  Both ports were required to make it functional.  The flight attendant had to try multiple times to get the correct wires into the correct ports.  I had to help the flight attendant get it connected properly.  Such a simple and important issue to fix.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bonus question:&lt;/strong&gt; Given that the multiple ports did not appear to be for redundancy, why was such a time-critical system not designed with a single port?&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="4095" LastEditDate="2015-12-23T22:41:05.747" LastActivityDate="2015-12-23T22:41:05.747" Title="How are the &quot;medical communication&quot; headset sockets on some airliners used?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;medical&gt;&lt;emergency-services&gt;&lt;headset&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12777" PostTypeId="2" ParentId="12775" CreationDate="2015-02-18T16:39:04.227" Score="20" Body="&lt;p&gt;Tilting the rotor doesn't do much, in fact the body will be tilting more than the rotor. The gyroscopic effect will work against you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cyclic increases lift on one side of the rotor which will tilt the rotor. Which will then move the craft in the correct direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words the cyclic system gives a more direct response to input.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-18T16:39:04.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12778" PostTypeId="2" ParentId="12775" CreationDate="2015-02-18T18:06:47.410" Score="18" Body="&lt;p&gt;Rachet Freaks answer is good, but I feel a bit incomplete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You ask why it needs a cyclic control.  Well, you need a control to tilt the disc, either directly or by flying it into position, so let's call that control the cyclic control (since it affects the rotor cyclically).  So whatever your mechanism, you need a cyclic control to tilt the disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what do we mean by tilt the disc?  It's splitting hairs a little bit, although precise, to distinguish between tilting the disc, and causing a cyclic change in lift to each blade such that the rotor flies into a tilt.  The reasons for flying it into a tilt are as Rachet Freak states.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You then state that it's complex, so let's examine physically tilting the disc versus cyclically altering the pitch of each blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cyclically altering blade pitch:&lt;/strong&gt;  The power shaft from the rotor gearbox passes through the middle of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Swashplate_%28aeronautics%29&quot; rel=&quot;noreferrer&quot;&gt;swashplate&lt;/a&gt; and is attached to the rotor.  The bottom of the rotating rotor is the rotating part of the swashplate which acts as a bearing surface rotating on the lower part of the swashplate which is non-rotating and fixed to the fuselage.  The blades are attached to the rotating swashplate with pitch links which can move to turn the blades in their cuffs.  Now all we need to do is to attach the cyclic control to the non-rotating swashplate so that we can tilt it.  In turn, this will tilt the rotating swashplate and the pitch links will transmit this to the blades, causing them to rotate in their cuffs, altering the angle of attack and therefore lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uCRno.png&quot; alt=&quot;Swashplate&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LeAzt.png&quot; alt=&quot;Swahplate&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By KoenB (blender drawing) [Public domain], via Wikimedia Commons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Physically tilting the disk:&lt;/strong&gt;  The first half of this is the same.  Just remove the pitch links so that the disc will physically follow the swashplate.  All good so far, and the only complexity you have removed are the pitch links attached to the blades to rotate them.  But now you have a problem.  You can only increase or decrease total lift by varying the power applied to the rotor from the engine and therefore the total rotor thrust.  The easiest way to solve this is to put the pitch links back and allow the blades to rotate in their cuffs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, trying to physically tilt the disc needs the same complexity as cyclically varying the pitch and loses a lot of the utility of the helicopter.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-02-19T21:43:51.853" LastActivityDate="2015-02-19T21:43:51.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12779" PostTypeId="2" ParentId="3322" CreationDate="2015-02-18T19:54:11.063" Score="1" Body="&lt;p&gt;As far as I can tell, according to the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0401.html&quot; rel=&quot;nofollow&quot;&gt;AIM 4-1-11&lt;/a&gt; you should use 122.9, which is described as follows (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(MULTICOM FREQUENCY) Activities of a temporary, seasonal, emergency&#xA;  nature or search and rescue, &lt;strong&gt;as well as&lt;/strong&gt;, airports with no tower, FSS,&#xA;  or UNICOM.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The words &quot;as well as&quot; indicate that it isn't just for use around airports, and aerobatic practice certainly sounds like a &quot;temporary&quot; activity. Of course, flight following would be preferable if it's available.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-02-18T19:54:11.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12781" PostTypeId="2" ParentId="12776" CreationDate="2015-02-18T20:30:39.860" Score="11" Body="&lt;p&gt;I'm going to assume you're talking about something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5w241.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5w241.jpg&quot; alt=&quot;Medical Emergency jacks&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Photo liberally stolen from &lt;a href=&quot;http://www.flyertalk.com/forum/delta-air-lines-skymiles/1500388-medical-communications-panel-763-a.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As other have mentioned, these are generally connections for a standard aviation headset (headphone and microphone plugs). When plugged in you're typically connected to the cockpit (so the pilots know what's going on), and on commercial airlines you may also be patched in to a medical consulting service via radio.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The principle behind this is similar to the early paramedic programs in the United States: Personnel with some basic training (like flight attendants) are connected to a doctor. They describe the patient's condition and symptoms, and the doctor advises on a course of treatment, which can begin immediately and hopefully give the patient a better chance of survival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radio patch can also be used &lt;a href=&quot;https://www.phyins.com/risk-management/taking-care/667/general/helping-a-sick-passenger-on-a-plane/&quot; rel=&quot;nofollow noreferrer&quot;&gt;by a doctor onboard the aircraft&lt;/a&gt; to consult with other physicians and to help the flight crew arrange for appropriate transport services to meet the plane when it lands.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-18T20:30:39.860" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12782" PostTypeId="1" AcceptedAnswerId="12788" CreationDate="2015-02-18T21:04:36.023" Score="21" ViewCount="16365" Body="&lt;p&gt;Blended wings are more beneficial when it comes to fuel efficiency increase and noise reduction. However, no manufacturer has decided to produce these airplanes for major airline operation so far. What are the inhibiting factors in the industry for not using this configuration?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I can guess:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is a complete new configuration with low experience on it. High risk.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft will be in VLA sector (&gt;500 passengers), a sector not very attractive nowadays.&lt;/li&gt;&#xA;&lt;li&gt;The 90 seconds evacuation limit needs to be observed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="13197" LastEditDate="2016-03-24T15:14:35.360" LastActivityDate="2017-10-12T04:47:54.310" Title="Why are there no blended-wing passenger airplanes in operation?" Tags="&lt;aircraft-design&gt;&lt;blended-wing&gt;" AnswerCount="8" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12783" PostTypeId="5" CreationDate="2015-02-18T21:05:24.070" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-02-18T21:05:24.070" LastActivityDate="2015-02-18T21:05:24.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12784" PostTypeId="4" CreationDate="2015-02-18T21:05:24.070" Score="0" Body="Is an airplane configuration where there is no clear distinction between the fuselage and the wing." OwnerUserId="6979" LastEditorUserId="62" LastEditDate="2015-02-18T21:40:45.803" LastActivityDate="2015-02-18T21:40:45.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12787" PostTypeId="2" ParentId="239" CreationDate="2015-02-19T00:51:22.143" Score="6" Body="&lt;p&gt;To add on to this old question, here's the load relief schedule for a 777-200ER.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lIGvV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-02-19T00:51:22.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12788" PostTypeId="2" ParentId="12782" CreationDate="2015-02-19T08:09:26.187" Score="29" Body="&lt;p&gt;All studies which so far showed an advantage for blended-wing bodies (BWB) were flawed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trick mostly used is to compare an existing airliner with a hypothetical BWB which uses equally hypothetical engines of improved efficiency, like what could be expected 20 years into the future. This masks the inefficiency of the BWB concept and makes the combination come out ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The BWB will always have more surface area than a comparable conventional design. This translates into more friction drag and more skin mass, which more than offsets any advantage given by the bigger wing root (which helps to reduce wing spar mass). If you like real data, use the &lt;a href=&quot;http://en.wikipedia.org/wiki/Avro_Vulcan&quot;&gt;Avro Vulcan&lt;/a&gt; as an early BWB and compare it to its contemporaries. Note that design attempts for an airliner based on the Vulcan (&lt;a href=&quot;http://www.abovetopsecret.com/forum/thread212956/pg1&quot;&gt;type 722 Atlantic&lt;/a&gt;) went nowhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are these BWB studies published? The author gets more attention when he/she claims a &quot;revolutionary breakthrough&quot; than when he/she is more honest and admits that the concept is a dud. Even Boeing or Airbus like to publish BWB studies, so the public gets the impression they are ahead of the competition. It is sickening to read such academically dishonest studies - you need to spend time to dig to the bottom of the thing and to unravel the plot; however, once you have done this a few times, they all become alike. But compared to studies made 60 or 80 years ago, where the author factually lists what he did and why it didn't work out (which is the only way you can learn something), those modern studies are a waste of time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-18T22:07:58.470" LastActivityDate="2015-11-18T22:07:58.470" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12790" PostTypeId="1" CreationDate="2015-02-19T11:58:39.467" Score="4" ViewCount="254" Body="&lt;p&gt;I am doing research about the number of flights and distance flown performed by aircraft types, in a given year. For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;There were X A320-200 flights, flying an average distance of Y nautical miles, in the year Z.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I know that these records are kept for all registered flights, so I am wondering if there is a database where one can find such info?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for data of as many regional flight airliners as possible.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="65" LastEditDate="2015-02-19T16:24:28.423" LastActivityDate="2015-02-19T18:07:21.773" Title="Is there a public database for annual flights by aircraft type?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;commercial-operations&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12791" PostTypeId="1" CreationDate="2015-02-19T12:45:09.517" Score="19" ViewCount="2353" Body="&lt;p&gt;I had thought that someone such as ICAO was coordinating the assignment of five-letter waypoint names such that they were globally unique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I notice that &lt;a href=&quot;http://www.opennav.com/&quot; rel=&quot;noreferrer&quot;&gt;OpenNav&lt;/a&gt; knows three different waypoints named PINTO, two of which are on the same continent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this supposed to happen? Are there rules for how close identically-named waypoints can be to each other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(A significant factor in the &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_965&quot; rel=&quot;noreferrer&quot;&gt;AA 965&lt;/a&gt; crash was that there were two NDBs with the same ID close to each other, and the FMC selected the wrong one to fly towards. This might be inevitable when NDBs usually have one- or two-letter IDs, but surely with a big fat five-letter namespace uniqueness ought to be achievable?)&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-02-19T16:54:09.213" LastActivityDate="2018-04-23T12:20:41.827" Title="How unique are waypoint names supposed to be?" Tags="&lt;airline-operations&gt;&lt;navigation&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12792" PostTypeId="2" ParentId="12791" CreationDate="2015-02-19T12:55:49.363" Score="11" Body="&lt;p&gt;The names are not globally unique and when entering the plan into the FMC, the crew should check the leg distance.  They are sufficiently far enough that the crew will see 1,812 miles instead of 135 miles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many FMCs will also only offer &quot;sensible&quot; choices and a deliberate action is required to select a &quot;nonsensical&quot; waypoint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often, a mistake in choosing the wrong waypoint will also alert them with a &quot;not enough fuel&quot; message, or an &lt;em&gt;obvious gross error&lt;/em&gt; such as a total distance of 3,323 miles instead of the 756 miles expected.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="30633" LastEditDate="2018-04-23T12:20:41.827" LastActivityDate="2018-04-23T12:20:41.827" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12793" PostTypeId="2" ParentId="12791" CreationDate="2015-02-19T13:59:42.960" Score="8" Body="&lt;p&gt;Each country's aviation authority is responsible for naming their own waypoints, so it's up to them how far they try to avoid duplication. In the US, the FAA's &lt;em&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/AIR.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Procedures for Handling Airspace Matters&lt;/a&gt;&lt;/em&gt; section &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/AIR/air0303.html#air0303.html.1&quot; rel=&quot;nofollow noreferrer&quot;&gt;3-3-4&lt;/a&gt; simply says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;e. AIM [Aeronautical Information Management] must not duplicate any radio fix, waypoint, marker beacons or&#xA;  compass locators names.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So they are (or should be) unique within the US, but they aren't guaranteed to be unique globally, although presumably other countries also have policies to avoid duplicate names. For example, &lt;a href=&quot;https://aviation.stackexchange.com/a/2867/62&quot;&gt;this answer&lt;/a&gt; quotes similar language from the UK's CAA and has some additional information.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-02-19T13:59:42.960" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12794" PostTypeId="2" ParentId="1070" CreationDate="2015-02-19T18:00:48.197" Score="0" Body="&lt;p&gt;Since we all agree that a 3.2°GS give us 340'/nm, I suggest that you take your FAA, subtract by the TCH elevatin and divide by 340, the result is the distance to touchdown &lt;/p&gt;&#xA;" OwnerUserId="7363" LastActivityDate="2015-02-19T18:00:48.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12795" PostTypeId="2" ParentId="12790" CreationDate="2015-02-19T18:07:21.773" Score="2" Body="&lt;p&gt;Short answer is &quot;no&quot;. There is no such thing as a &quot;registered&quot; flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cases where pilots have filed flight plans, you could aggregate that data. It would be a BIG programming project. There are commercial services that analyze flight plan data. They might be willing to help you for a price that would be in the 10's of thousands of dollars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight plan data would only be good for US information. Other countries would require other data collection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small planes usually don't file flight plans, but you may not care about this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft manufacturers estimate how much their planes fly around. Whether they would be willing to share this data with you, I don't know.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-19T18:07:21.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12797" PostTypeId="2" ParentId="12776" CreationDate="2015-02-19T18:47:24.180" Score="6" Body="&lt;p&gt;To answer your questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The headset allows the steward to talk on the aircraft's common channel which the pilot can connect to any radio frequency. Normally the steward will be talking both the captain and possibly to the tower of the arrival airport. The tower can patch in phone lines. So, if necessary, the tower can telephone a doctor, then patch in the doctor to the frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases the comm link is just to make sure that arriving emergency personnel have the right information. For example, what might happen is the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Captain calls tower: &quot;We have a medical emergency on board.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tower tells captain: &quot;Okay, emergency services are on their way.&quot; (An ambulance will greet the aircraft as soon as it lands.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stewardless plugs and talks to tower: &quot;The passenger says he is diabetic. A doctor here on the plane says it looks like insulin shock.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tower (on the line with 911): &quot;Hello, it looks like our passenger is diabetic and going into insulin shock&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;911 calls ambulance on radio: &quot;Patient is diabetic and may be experiencing insulin shock.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This is just one scenario, but it is typical. Basically one person relays information to the next and the steward is the first link in that chain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your second question: aviation headsets have two ports: one for the earphones (listening) and the other for the microphone (speaking). The plugs are designed for ruggedness and reliability and are 1960s technology. In theory a more convenient duplex plug system could be used, but out of conservatism that has not happened yet.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-19T18:47:24.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12798" PostTypeId="1" AcceptedAnswerId="12800" CreationDate="2015-02-19T18:48:32.163" Score="8" ViewCount="9066" Body="&lt;p&gt;Consider this NOTAM for LAX from the &lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/notamRetrievalByICAOAction.do?method=displayByICAOs&amp;amp;reportType=RAW&amp;amp;formatType=DOMESTIC&amp;amp;retrieveLocId=LAX&amp;amp;actionType=notamRetrievalByICAOs&quot; rel=&quot;noreferrer&quot;&gt;current list&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FDC 5/0341 LAX IAP LOS ANGELES INTL LOS ANGELES CA. ILS OR LOC RWY 25L AMDT 12C... S-ILS 25L DA 395/ HAT 291 ALL CATS VISIBILITY ALL CATS RVR 2200. ADD NOTE FOR INOPERATIVE ALSF-2 INCREASE S-ILS 25L VISIBILITY ALL CATS TO RVR 4500. EXCEPT WHEN ADVISED BY ATC THAT EQUIPMENT IS DOWN. CONSTRUCTION EQUIPMENT 178 MSL BEGINNING 1399 FEET NORTHEAST OF RWY 25L. 1502052152-1508042152EST&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does &lt;code&gt;S-ILS25L&lt;/code&gt; signify, how is it different than just &lt;code&gt;ILS25L&lt;/code&gt;, and where can I find the source document?&lt;/p&gt;&#xA;" OwnerUserId="7365" LastEditorUserId="572" LastEditDate="2015-02-19T20:14:22.147" LastActivityDate="2015-02-20T07:47:05.200" Title="What does &quot;S-ILS&quot; signify in an FAA NOTAM?" Tags="&lt;faa-regulations&gt;&lt;instrument-procedures&gt;&lt;notam&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12800" PostTypeId="2" ParentId="12798" CreationDate="2015-02-19T18:53:27.683" Score="7" Body="&lt;p&gt;The &lt;code&gt;S&lt;/code&gt; is for the straight-in portion of that approach (this is explained in the Abbreviations section of the Terminal Procedures Publication (&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/&quot; rel=&quot;noreferrer&quot;&gt;See here&lt;/a&gt; - it's in the Abbreviations section of &quot;Legends and General Information&quot; at the bottom).  In this case the decision altitudes, height above thresholds, and weather minimums have changed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7szFM.png&quot; rel=&quot;noreferrer&quot;&gt;Check out the approach plate&lt;/a&gt; and at the bottom you'll see S-ILS 15, S-LOC/DME 15, CIRCLING, etc.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorUserId="64" LastEditDate="2015-02-19T19:04:13.583" LastActivityDate="2015-02-19T19:04:13.583" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12801" PostTypeId="5" CreationDate="2015-02-19T20:20:44.740" Score="0" Body="&lt;p&gt;For a detailed explanation of the Commercial Pilot License, check &lt;a href=&quot;http://en.wikipedia.org/wiki/Commercial_pilot_license&quot; rel=&quot;nofollow&quot;&gt;WikiPedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-19T20:47:24.917" LastActivityDate="2015-02-19T20:47:24.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12802" PostTypeId="4" CreationDate="2015-02-19T20:20:44.740" Score="0" Body="A Commercial Pilot License allows a pilot to fly for money. This license is a level above the Private Pilot License." OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2015-02-19T20:36:59.670" LastActivityDate="2015-02-19T20:36:59.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12804" PostTypeId="2" ParentId="12770" CreationDate="2015-02-19T21:14:02.780" Score="3" Body="&lt;p&gt;Maybe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.x-plane.com/pro/landing/&quot; rel=&quot;nofollow&quot;&gt;From the page linked by falstro above&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These include the ability to use cylindrical and spherical projection (as found in large simulators), and the ability to drive real Garmin 1000, Garmin 430, Garmin 430 WAAS, Garmin 530, and Garmin 530 WAAS units.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pictures are included of a particular setup. The large projection format allows all-around visuals. The simulator can drive &lt;em&gt;real&lt;/em&gt; Garmin devices, not just replicas. They recommend &lt;a href=&quot;https://www.flypfc.com/&quot; rel=&quot;nofollow&quot;&gt;this vendor&lt;/a&gt; for FAA approved hardware (and for &lt;a href=&quot;https://www.flypfc.com/?/products/yokes/cirrus-cessna-yoke/&quot; rel=&quot;nofollow&quot;&gt;$2,100&lt;/a&gt; I would hope a yoke could be FAA certified).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use an IOS even with the personal license for the simulator, on the same computer or a separate one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.x-plane.com/pro/certified/&quot; rel=&quot;nofollow&quot;&gt;X-Plane also explains&lt;/a&gt; that only the complete hardware+software combination can be certified for use as an FAA approved flight simulator. So it may be easier to just buy a package from a company &lt;a href=&quot;https://www.flypfc.com/&quot; rel=&quot;nofollow&quot;&gt;like PFC&lt;/a&gt;, which has the combination already certified. They offer BATD and AATD simulator setups that use X-Plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need more information, you can contact X-Plane via the link on the same site &lt;a href=&quot;http://www.x-plane.com/pro/landing/&quot; rel=&quot;nofollow&quot;&gt;linked above&lt;/a&gt;. They do not keep track of what people use their professional licenses for, but they may be able to comment on what level of certification is achievable.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-19T21:14:02.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12806" PostTypeId="1" AcceptedAnswerId="12807" CreationDate="2015-02-19T23:22:23.113" Score="44" ViewCount="48787" Body="&lt;p&gt;When I get a chance to peek inside an engine, I noticed that many have spiral marks painted in the center. What is the purpose of these?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pictures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://cache2.asset-cache.net/gc/155373940-aircraft-engine-gettyimages.jpg?v=1&amp;amp;c=IWSAsset&amp;amp;k=2&amp;amp;d=9nW9PqrReJW%2FoXgBU3a7qvCHc7EPjanwZeKvpwCcgis%3D&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PvKR7.jpg&quot; alt=&quot;Spiral on CFM-56 engine on an A320&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aerospaceweb.org/aircraft/jetliner/a380/a380_13.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7kMFM.jpg&quot; alt=&quot;Spirals on Rolls Royce Trent 900 engines on an A380&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="3386" LastEditDate="2017-11-03T13:20:56.320" LastActivityDate="2018-04-25T21:48:51.633" Title="What are the spiral marks in the center of the engines?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;airliner&gt;&lt;bird-strike&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12807" PostTypeId="2" ParentId="12806" CreationDate="2015-02-19T23:22:23.113" Score="42" Body="&lt;p&gt;The benefit of these white markings inside the engine is twofold:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The ground crew can tell if the engine is running or not.&lt;/strong&gt;&lt;br&gt;&#xA;When an airplane is at the gate before departure, there are several personal &lt;em&gt;attending&lt;/em&gt; the airplane. They would be loading luggage, refueling, removing waste products, loading food, &lt;em&gt;etc. etc.&lt;/em&gt;. Not all of these people are in constant contact with the pilots and they can come very close to the engines. Although there are several precautionary measures taken before the pilots turn on the engines, it is a very clear visual indication by looking at the spirals to tell if the engines are running or not. &lt;a href=&quot;http://www.aerospaceweb.org/question/propulsion/q0233a.shtml&quot; rel=&quot;noreferrer&quot;&gt;Rotor or prop blades sometimes have their tips painted for the same reason.&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The birds keep away.&lt;/strong&gt;&lt;br&gt;&#xA;During flight, when the engine is running, birds see the spinning spiral as opposed to just a black hole, and hence they stay away from it. It is like an anti-bird signal because if there was nothing in the middle it just looks like a cave or black void that birds tend to fly toward. Even though it looks like a blur to us, birds can see motion better. &lt;a href=&quot;http://en.wikipedia.org/wiki/Bird_strike&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia mentions&lt;/a&gt; this also:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... it appears as a white circle which discourages birds from flying into the engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://web.archive.org/web/20061019190934/http://100.rolls-royce.com/files/852/facts_100.pdf&quot; rel=&quot;noreferrer&quot;&gt;Rolls-Royce brochure (PDF)&lt;/a&gt; quoted the following &lt;em&gt;(identified by user &lt;a href=&quot;https://aviation.stackexchange.com/users/3159/bowlofred&quot;&gt;BowlOfRed&lt;/a&gt; in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12806/what-are-the-spiral-marks-in-the-center-of-the-engines#comment27580_12807&quot;&gt;comment below&lt;/a&gt;)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Our aerospace engines have swirls painted onto their spinners in order&#xA;  to indicate when the engine is rotating while on the ground. In flight&#xA;  these swirls flicker as the engine rotates at high speed, scaring&#xA;  birds and allowing them to fly clear of the engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-02-22T17:14:54.440" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12808" PostTypeId="2" ParentId="12806" CreationDate="2015-02-20T00:59:10.240" Score="20" Body="&lt;p&gt;The spiral on many GE engines is a stylized &quot;G&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bgOcP.png&quot; alt=&quot;GE spiral and logo&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.geaviation.com/manufacturing/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls Royce has a longer spiral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cHdg6.jpg&quot; alt=&quot;Rolls Royce spiral&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design helps with ground crew safety, &lt;a href=&quot;https://aviation.stackexchange.com/a/12807/1696&quot;&gt;as Farhan's answer discusses&lt;/a&gt;. However, it is not required and not all engines have them, suggesting that they are also a matter of style between engines and manufacturers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/&quot; rel=&quot;nofollow noreferrer&quot;&gt;This page from Boeing&lt;/a&gt; about bird strikes says that there is no scientific evidence that spinner markings, airplane colors, landing lights, or weather radar deter birds. On the other hand, &lt;a href=&quot;http://www.museumofflight.org/faq/what-weird-black-shape-painted-front-747%E2%80%99s-jet-engines&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Museum of Flight states that&lt;/a&gt; &quot;research has shown&quot; the spiral deters birds. Though I suppose this research could have been unscientific.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2005/August/1/Bird-Strike&quot; rel=&quot;nofollow noreferrer&quot;&gt;The AOPA says that&lt;/a&gt; &quot;one air carrier detected slightly reduced bird strike rates after painting the jet engine spinners white.&quot; If there is indeed an effect here, it would seem that a spiral would be less effective than painting them white.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www2.vlieghinder.nl/naslagdocs/CDrom/REGELS_SCHIPHOL/2.3_TNL/4.3.4.1_Bird_control_at_airports.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This paper&lt;/a&gt; notes mixed results on using eye spots on aircraft. When used on the ground, the birds seem to get used to them quickly, just as they do with the noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As costly as bird strikes can be, it would seem that aircraft operators would widely adopt anything shown to help prevent them.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-02-20T20:54:53.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12810" PostTypeId="1" AcceptedAnswerId="12818" CreationDate="2015-02-20T01:55:52.677" Score="34" ViewCount="2498" Body="&lt;p&gt;The airspace between Russia and Norway over the Barents Sea is an uncontrolled air space; no &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_information_region&quot; rel=&quot;noreferrer&quot;&gt;FIR&lt;/a&gt; is set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Mpixt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Mpixt.jpg&quot; alt=&quot;map of the Arctic flight information regions&quot;&gt;&lt;/a&gt;&#xA;Illustration taken from &lt;a href=&quot;http://www.amap.no/documents/download/938&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This area is like a corridor from the Scandinavian peninsula to the North Pole. It only requires several minutes by a heavy airliner to pass east-west.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this relatively small area not controlled?&lt;/p&gt;&#xA;" OwnerUserId="7372" LastEditorUserId="12679" LastEditDate="2017-10-23T16:07:29.353" LastActivityDate="2019-10-12T18:50:06.967" Title="Why is there a strip of uncontrolled airspace between Russia and Norway?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;international&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12811" PostTypeId="2" ParentId="738" CreationDate="2015-02-20T03:06:50.430" Score="11" Body="&lt;p&gt;Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You tell me??&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First a story on flight simulation...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number one defense contractor in the world. Lockheed Martin purchased the code for Microsoft Flight Simulator and turned it into &lt;a href=&quot;http://www.prepar3d.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Prepar3D&lt;/a&gt;.&#xA;Why would the makers of the F-22, F-16, F-35, C-130, C-5 do this if there was not something to it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In today's world of drones, and children growing up with tech, Lockheed figured out an ingenious plan to save the military tons of money and make a profit.&#xA;By shifting training to a virtual environment including virtual reality software, flight simulators and even full on level D simulators the military will save money. Why spend \$14,000 per flight hour for a C-130 when you can simulate it. The full level D is \$800 per hour. And \$68,362 for a F-22... versus \$800.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everything is going virtual in the military....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even deicing...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airforce-technology.com/news/newsusaf-improves-aircraft-deicing-training-with-new-simulator-4486616&quot; rel=&quot;nofollow noreferrer&quot;&gt;De-icing simulator&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/L5RVw.jpg&quot; alt=&quot;USAF using FS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically you start at what is the equivalent of flight simulator, and work your way up to MFTA's and finally to a level D class sim..... then you move on to the real plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key is instruction....&lt;img src=&quot;https://i.stack.imgur.com/Ow6ra.jpg&quot; alt=&quot;F-22 training&quot;&gt; Being a trained pilot, yes you can go back to flight sim and practice.. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To conclude.....I am an FAA licensed Private pilot. I also have flown on VATSIM with flight simulator for over 10 years and flown everything from a C-172,  to a C-17 to a Boeing 777....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So could I really fly those?? Cessna... yes...but something bigger?? Yes after a very basic briefing by an instructor( takeoff speeds, landing speeds etc...) I solo'd a C-130 on my first flight. Well the Level D one.... at least. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mCQ43.jpg&quot; alt=&quot;C-130 Simulator&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7374" LastEditorUserId="1696" LastEditDate="2019-11-22T17:01:40.477" LastActivityDate="2019-11-22T17:01:40.477" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="12813" PostTypeId="2" ParentId="738" CreationDate="2015-02-20T03:59:17.413" Score="5" Body="&lt;p&gt;Yes it can. That is the purpose of a flight simulator. In fact, they are designed to help improve your judgement. Even though most simulators do not achieve this feel perfectly, your brain senses an upcoming object as the source, and therefore, your judgement comes into play.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, flight simulators do not give you the full experience, such as fear. Many times people get scared on their first flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suggest looking at guides or manuals of planes to completely operate them to their full potential. Think of flying a plane almost like driving a car. You need quick judgement to apply the brakes, and not get scared when a car drives too close. Though it is not completely comparable to a car, it takes a lot less time to stop it then to safely stop a airplane. Now I'm not an expert on flight, but I know enough.&lt;/p&gt;&#xA;" OwnerUserId="7375" LastEditorUserId="595" LastEditDate="2015-06-17T13:58:33.507" LastActivityDate="2015-06-17T13:58:33.507" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12814" PostTypeId="1" CreationDate="2015-02-20T08:02:43.830" Score="8" ViewCount="3000" Body="&lt;p&gt;A few years back the FAA was upset about young pilots attempting to set records and crashing in the process. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were there any rules instituted regarding logging of time with a CFI / instructor? May a 9 year old or 12 year old log time flown with a CFI and use that time to qualify for a rating?&lt;/p&gt;&#xA;" OwnerUserId="7376" LastEditorUserId="62" LastEditDate="2015-02-20T14:11:30.583" LastActivityDate="2015-02-20T15:30:17.933" Title="At what age may a student log time and use that time to obtain a rating?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;logging&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12815" PostTypeId="1" AcceptedAnswerId="12816" CreationDate="2015-02-20T09:01:16.157" Score="30" ViewCount="6864" Body="&lt;p&gt;In this book, &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/The_Making_of_the_Atomic_Bomb&quot;&gt;The Making of the Atomic Bomb&lt;/a&gt;&lt;/em&gt; by Richard Rhodes (p. 705), I read:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Paul Tibbets] eased the brakes [of &lt;em&gt;Enola Gay&lt;/em&gt;] at 0245, the four fuel-injected Wright Cyclone engines pounding. “The B-29 has lots of torque in take-off,” he notes. “It wants to swerve off the runway to the left. The average mass-production pilot offsets torque by braking his right wheels. It's a rough ride, you lose ten miles an hour and you delay the take-off.” Nothing so rude for Tibbets. “Pilots of the 509th Group were taught to cancel torque by leading in with the left engines, advancing throttles ahead of the right engines. At eighty miles an hour, you get full rudder control, advance the right-hand engine to full power and, in a moment, you're airborne.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not especially knowledgeable in aviation matters, but I believe that the torque is due to the B-29's four propellers all rotating in the same direction. Is that right? If so:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Why did this problem only arise during take-off?&lt;/li&gt;&#xA;&lt;li&gt;Why did all propellers rotate the same way? Is this true for all propeller-driven aircraft with more than one engine? Why?&lt;/li&gt;&#xA;&lt;li&gt;If the 509th Group's technique was so good (and apparently not especially complex), why did only they use it?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="705" LastEditorUserId="2171" LastEditDate="2015-02-20T19:30:17.550" LastActivityDate="2015-02-20T19:30:17.550" Title="Why did the B-29 have so much leftward torque at take-off?" Tags="&lt;propeller&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12816" PostTypeId="2" ParentId="12815" CreationDate="2015-02-20T09:58:06.597" Score="39" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It didn't arise ONLY during takeoff, but it is most noticeable then for several reasons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engines are at maximum power, therefore producing maximum torque&lt;/li&gt;&#xA;&lt;li&gt;You've got a very good reason to need to be travelling in an exactly straight line (the runway)&lt;/li&gt;&#xA;&lt;li&gt;You're travelling at fairly slow speed, so your vertical stabilizer is less effective - at higher speeds, the tail counteracts the torque more effectively (for this B-29 this occurs at 80mph, as mentioned). As soon as you get above 80mph, you can just input a little right rudder to counteract it.... B-29's only travelled below 80mph on takeoff and landing, so it wasn't a problem during flight, and during landing the throttles were at idle or very low power.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It isn't true for all aircraft with more than one engine now (although it is true for some), but it does still happen and was much common back in WWII - they didn't want the extra supply line complexity of two different sets of otherwise identical engines, when it could be solved with a bootfull of right foot. Note also that the B-29 had 4 engines, most modern multi-props only have two, and they're closer to the fuselage, which reduces the effect&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I think you're misinterpreting the source: he's not saying this technique was unique to the 509th, just that they were taught the technique. The very fact he says they were taught it, rather than &quot;came up with&quot; it, suggests it was known elsewhere. The 509th are only referenced here because that's the group Tibbets was part of, it's unrelated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-02-20T11:18:23.930" LastActivityDate="2015-02-20T11:18:23.930" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12818" PostTypeId="2" ParentId="12810" CreationDate="2015-02-20T10:00:44.230" Score="38" Body="&lt;p&gt;&lt;strong&gt;Details of the No FIR area&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The area extends on 175,000 square kilometers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From ≈70°N (Bodø FIR) to the North Pole.&lt;/li&gt;&#xA;&lt;li&gt;From 30°E to ≈32°05'E, and to 35°E for a portion east of Svalbard archipelago.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2q2f5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2q2f5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;VATSIM Murmansk sectors (ATC simulation). &lt;a href=&quot;http://vatsim-scandinavia.org/wp-content/uploads/2012/12/LoA-ENBD-ULMM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Border dispute&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This Barents Sea strip is of major importance, and has been subject to a dispute between Norway and Russia for 44 years. The reasons include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;This area has been the maritime border between East and West blocks during Cold War (the country is neutral, but still a founding member of the NATO).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Norway is a country with many resources coming from the sea (fish, oil, gas), the sea area controlled by the State is six times its land area. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Barents Sea is a location with multiple oil and gas fields to be exploited. The large &lt;a href=&quot;https://en.wikipedia.org/wiki/Shtokman_field&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shtokman gas field&lt;/a&gt; (label &quot;5&quot; below) discovered in 1988 happens to be in the vicinity, an agreement was signed between Norway and Russian Federation for the development of the field, but only in 2005:&lt;br&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aEvMB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aEvMB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Oil and Gas in the Barents Sea (red dots are gas fields). &lt;a href=&quot;https://mem.lyellcollection.org/content/35/1/295/tab-figures-data&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The area encompasses the most direct potential route between Europe and the Pacific after the ice floe has melt down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This dispute was closed when a new &lt;a href=&quot;http://en.wikipedia.org/wiki/Norway%E2%80%93Russia_border#Delimitation_agreement&quot; rel=&quot;nofollow noreferrer&quot;&gt;treaty entered in force on July 2011&lt;/a&gt; with the border crossing the 175,000 square kilometers disputed region in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BADHe.gif&quot; alt=&quot;Norway-Russia disputed border area&quot;&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;http://www.bbc.co.uk/news/business-11316430&quot; rel=&quot;nofollow noreferrer&quot;&gt;BBC&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the border is now settled, responsibilities for air traffic control are still to be formally defined by international bodies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently transiting flights have to be authorized by respective authorities before operating in this area, e.g. London-Tokyo flights using &lt;em&gt;Arctica 1&lt;/em&gt; route, noted B483 on first picture. In addition of commercial flights, the Arctic region is highly monitored by manned and unmanned aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO and Eurocontrol status&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO wants to resolve this issue of missing FIR:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;8.1 IATA brought the attention of the Group to a portion of airspace of unassigned responsibility, extending from the North Pole over the&#xA;  High Seas between Bodo Oceanic FIR, Sondrestrom FIR and Murmansk&#xA;  Oceanic FIR (Appendix E refers). Considering the increase d interest&#xA;  of establishing new ATS routes through that airspace, the Group agreed&#xA;  on the following Conclusion:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;TRASAS Conclusion 2/4 – Airspace of Unassigned Responsibility over the&#xA;  Arctic Ocean&lt;br&gt;&#xA;  That the ICAO Secretariat be invited to take the&#xA;  necessary actions to resolve the pending issues regarding the portions&#xA;  of airspace of unassigned responsibility extending over the High Seas&#xA;  between Bodo Oceanic FIR, Sondrestrom FIR and Murmansk Oceanic FIR&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source:&lt;br&gt;&#xA;&lt;a href=&quot;http://www.jbaa.org/japanese/ICAOBangkok.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Report of the Second Meeting of the Trans-Regional Airspace and Supporting ATM Systems Steering Group (TRASAS/2) (Bangkok, Thailand, 18-19 March 2008)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a proposal under Eurocontrol auspices (proposal 95.012) to close the topic by Summer 2021:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FIR border realignment Murmansk FIR / Bodø FIR / Norway FIR:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Objective: To resolve the long-standing issue of the unallocated&#xA;  airspace (NO-FIR area) between Murmansk FIR and Bodø FIR / Norway FIR.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://www.eurocontrol.int/archive_download/all/node/10459&quot; rel=&quot;nofollow noreferrer&quot;&gt;European Route Network Improvement Plan 2019-2024&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No aeronautical services&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying in a no FIR area (when such territory is not forbidden to aircraft) means there is no information service provided from the ground. Flight information service consists on informing aircraft about meteorological events, known other aircraft position and intentions and aids availability. &lt;a href=&quot;https://www.theairlinepilots.com/forumarchive/quickref/icao/annex11.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Other services&lt;/a&gt; are not available either: No alerting (search and rescue) and no ATC. The related airspace belongs to none of A, B, C, ..., G classes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who want to know more about FIR and Oceanic Control Area, see &lt;a href=&quot;https://aviation.stackexchange.com/q/25215/3201&quot;&gt;Who manages International Airspace Traffic?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No FIR areas in general&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the existence of &quot;No FIR&quot; areas:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3) FIRs have not been established for a few areas in the world.&#xA;  These are commonly called uncontrolled information regions or “no&#xA;  man’s land.” The largest of these areas is in the South Atlantic&#xA;  Ocean, annotated as “No FIR.” Flight Information Services (FIS) also&#xA;  do not exist in the high altitude structure in other large areas&#xA;  (above the top of controlled airspace). Within no man’s land, aircraft&#xA;  separation (prevention of collision) is entirely the responsibility of&#xA;  the PIC. Advice and information for the safe and efficient conduct of&#xA;  flights is not provided from an ATS unit. An ATS unit does not provide&#xA;  alerting services related to search and rescue.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://fsims.faa.gov/PICResults.aspx?mode=EBookContents&amp;amp;restricttocategory=all~menu&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA 8900.1 - Flight Standards Information Management System&lt;/a&gt; - FSIMS (&lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v04%20ac%20equip%20&amp;amp;%20auth/chapter%2001/04_001_005.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vol 4-105-C-3&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-10-12T18:50:06.967" LastActivityDate="2019-10-12T18:50:06.967" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="12819" PostTypeId="2" ParentId="12814" CreationDate="2015-02-20T14:01:17.330" Score="9" Body="&lt;p&gt;FAR &lt;a href=&quot;http://www.flightsimaviation.com/data/FARS/part_61-83.html&quot; rel=&quot;noreferrer&quot;&gt;§ 61.83&lt;/a&gt; states:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;To be eligible for a student pilot certificate, an applicant must:&lt;/p&gt;&#xA;&lt;p&gt;(a) Be at least 16 years of age for other than the operation of a glider or balloon.&lt;/p&gt;&#xA;&lt;p&gt;(b) Be at least 14 years of age for the operation of a glider or balloon.&lt;/p&gt;&#xA;&lt;p&gt;(c) Be able to read, speak, write, and understand the English language. [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A &lt;strong&gt;student pilot certificate&lt;/strong&gt; enables you to fly a plane solo or on a solo cross country.&#xA;In other words, you need to be at least 16 years old to fly a plane (non glider/balloon) solo.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SlCD6.jpg&quot; alt=&quot;This is an example of a student pilot certificate. It comes with your medical usually.&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Now, back to your initial question. If you go through FAR &lt;a href=&quot;http://www.flightsimaviation.com/data/FARS/part_61.html&quot; rel=&quot;noreferrer&quot;&gt;§61.83 - §61.95&lt;/a&gt; you will find all the regulations about student pilots (which would be the kind of pilot you are referring to ).&lt;/p&gt;&#xA;&lt;p&gt;I have found &lt;strong&gt;no age restriction&lt;/strong&gt; going through them for the pre-solo instruction. All it says that it must be done before soloing which does require a medical exam and certificate (&lt;a href=&quot;https://www.faa.gov/licenses_certificates/medical_certification/faq/response7/&quot; rel=&quot;noreferrer&quot;&gt;but these don't have age restrictions either&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Summing up, a 9 or 12 year old child is legally able to take flying lessons with an instructor, but may not solo before his/her 16th birthday (no glider/balloons).&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-20T15:30:17.933" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12821" PostTypeId="1" AcceptedAnswerId="12822" CreationDate="2015-02-20T20:17:12.357" Score="47" ViewCount="29830" Body="&lt;p&gt;As shown in the images below, what are these wavy lines on the canopy of the aircraft? Do these lines have any utility?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are mostly captured in videos of cockpit views of &lt;em&gt;carrier-based&lt;/em&gt; aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/emUry.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AdjuK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="1696" LastEditDate="2018-04-25T21:39:28.847" LastActivityDate="2018-04-25T21:39:28.847" Title="What are these wavy lines on fighters' canopy?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;jet&gt;&lt;cockpit&gt;&lt;canopy&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12822" PostTypeId="2" ParentId="12821" CreationDate="2015-02-20T20:30:37.963" Score="51" Body="&lt;p&gt;It is an &lt;a href=&quot;http://en.wikipedia.org/wiki/Detonating_cord&quot;&gt;explosive cord&lt;/a&gt; which helps to &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000109968.pdf&quot;&gt;crack the canopy (pdf!)&lt;/a&gt; before the ejection seat has to do this all by itself. When ejection is commanded, the harness is tightened and the canopy is shattered, and only then the real ejection starts. Earlier designs would blow the full canopy off, but this takes longer than shattering it, especially when the canopy is large.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some seats have their own canopy breakers, but thick, tough canopies which are needed for flying at high dynamic pressure and for surviving bird strikes would slow the seat down too much. The F-16 canopy is 12mm thick in the area above the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are used widely for both land- and carrier-based aircraft, and modern designs try to make them less obvious. The F-35 canopy uses just one line down the middle.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-20T21:19:29.117" LastActivityDate="2015-02-20T21:19:29.117" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="12823" PostTypeId="1" AcceptedAnswerId="12828" CreationDate="2015-02-20T20:48:47.210" Score="31" ViewCount="70416" Body="&lt;p&gt;Looking at &lt;a href=&quot;https://aviation.stackexchange.com/questions/12821/what-are-these-wavy-lines-on-fighters-canopy&quot;&gt;this&lt;/a&gt; question I remembered a question I always wanted to ask:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the movie &quot;Top Gun&quot; one of the main characters dies when trying to eject from the F-14. &lt;a href=&quot;https://www.youtube.com/watch?v=jeK7NQnulbM&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; is the scene where this happens. &lt;strong&gt;Did an incident like this ever occur in real life, or is there at least a theoretical possibility that a pilot could be killed this way?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Top Gun was filmed in the mid 80s, which is quite a while ago. If there were incidents, did they do something to fix that issue? And this question goes not only for F-14s but also other aircraft with ejection seats.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2019-11-23T21:23:00.693" Title="Could someone really die in the way that Goose did in the movie &quot;Top Gun&quot;?" Tags="&lt;accidents&gt;&lt;ejection-seat&gt;" AnswerCount="9" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12824" PostTypeId="2" ParentId="12821" CreationDate="2015-02-20T21:42:28.967" Score="31" Body="&lt;p&gt;For completeness, there are also several other mechanisms to make sure the pilot does not &quot;punch through&quot; the canopy, which would likely be fatal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As well as the detonating cord, many canopies unlock at the front when the ejection handle is pulled.  The airflow gets under the lip of the canopy and tears it off the aircraft.  The hinges at the back are designed to break in this scenario.  Other canopies have explosive charges which detach the canopy.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot;&gt;The Harrier&lt;/a&gt;, amongst other examples, might require the pilot to &lt;a href=&quot;https://www.youtube.com/watch?v=MBUWW5P1xCY&quot;&gt;eject at zero or low forward airspeed&lt;/a&gt; so utilises detonating cords to make sure that the canopy is shattered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some seats also have a rail which extends upwards at the start of the sequence, the top of the rail being designed to shatter the canopy.  The seat then travels up the rail.  The seat itself might also have &quot;canopy buster&quot; spikes fitted at the top such that if the canopy does not detach or shatter, the seat will break through the canopy and the pilot will not be too shredded by the broken plexi-glass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ejection sequence is carefully controlled with mechanical timers which, although everything happens fast, make sure that the pilot does not hit the canopy and is ejected clear of the aircraft.  &lt;a href=&quot;http://www.martin-baker.com/products/ejection-seats/mk11#tabFunctions&quot;&gt;It's very complex&lt;/a&gt;, with a sequence of pins being withdrawn, timers started, rockets fired and so on but at least one manufacturer, Martin Baker, has a proud record of never having had a seat failure other than for user or maintenance error.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-02-20T22:42:18.007" LastActivityDate="2015-02-20T22:42:18.007" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12825" PostTypeId="2" ParentId="12823" CreationDate="2015-02-20T21:59:10.853" Score="5" Body="&lt;p&gt;I suspect that no-one here has the expertise necessary to answer this with absolute certainty.  This answer is supposition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident started with a double flame out, precipitated by flying through the exhaust of the other aircraft, following which it entered a flat spin.  In this condition, it would be &lt;strong&gt;possible&lt;/strong&gt; although &lt;strong&gt;unlikely&lt;/strong&gt; that the canopy could remain above the aircraft and the crew member be ejected up into it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been real world incidents of ejecting crew members hitting canopies. I'll come back and edit with links or citations if I can find any.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the words of Mythbusters, I would say that this myth is &quot;plausible&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yee hah, Jester's dead.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-02-20T21:59:10.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12826" PostTypeId="2" ParentId="12823" CreationDate="2015-02-20T22:18:50.890" Score="20" Body="&lt;p&gt;This question &lt;a href=&quot;http://www.freerepublic.com/focus/bloggers/2214848/posts&quot; rel=&quot;nofollow noreferrer&quot;&gt;has been asked before&lt;/a&gt; on the Net, and there are some who say it happened once in advanced training operations. Unfortunately, I found no detailed reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the likelihood of the events which lead to the ejection sequence, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ejection sequence is at least factually wrong when showing both seats being ejected almost simultaneously. In the F-14, first the backseater (RIO - radar intercept officer) would eject, and the ejection of the pilot would happen 0.4 s later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ejection system of the F-14 was certified for 0-0 ejection (on the ground and at rest), and the canopy would be thrown backwards by an explosive charge. In a flat spin, a case not anticipated during development, it is possible that the canopy stays trapped in the turbulent, separated flow above the airplane, and then the first seat to come out has a chance of hitting it. At least this detail is not impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ejection is a violent process, and limbs have been dislocated and/or broken, and pilots have been knocked unconscious during ejection. Hitting the canopy in a still accelerating seat could indeed knock the seat's occupant unconscious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was fixed at least so far that a technique was developed to end the flat spin of an F-14. For other aircraft the system is tested and certified with the aircraft at rest, so hitting the canopy in a mid-flight ejection is impossible when the jettison mechanism works as intended. There have been cases, though, where the canopy failed to separate, and then an interlock would prevent the seat from firing. More modern designs use canopy breakers for clearing the way through a closed canopy, but they work only around the head. I don't want to know how the pilot's knees get mangled form the acrylic (or - even worse - the polycarbonate) when it is their time to clear the canopy.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-20T22:28:09.710" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12828" PostTypeId="2" ParentId="12823" CreationDate="2015-02-21T11:21:24.023" Score="40" Body="&lt;p&gt;Some sources I found claiming the event was real:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A flat spin creates a low-pressure area and stalls the canopy when&#xA;  ejected. Producers wanted a midair crash but based this accident on a&#xA;  real-life incident instead.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://blogs.amctv.com/movie-blog/2011/08/story-notes-trivia-top-gun/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The way Goose died was actually based on a real life incident that&#xA;  happened to a 14 crew in the Navy. Don't remember the specifics, just&#xA;  found this out recently while reading an article in one of last months&#xA;  flying mags (not Flying)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/169310/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have a photo of the 'real' Goose and it's true that he died of seat&#xA;  ejections but not exactly like the movie.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.fightercontrol.co.uk/forum/viewtopic.php?f=316&amp;amp;t=42644&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;, with pictures)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also an interview of Steven C. Schallhorn, who apparently was one of top gun instructors interviewed for the movie:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dr. Schallhorn said during his interview for the movie, he explained&#xA;  how a flat spin could actually happen with an F-14 and that it&#xA;  complicates ejection. &quot;The aerodynamics of the F-14 flat spin affect&#xA;  the timing of the ejection sequence,&quot; Dr. Schallhorn said. &quot;The canopy&#xA;  is jettisoned, followed by the ejection of the back seat, followed by&#xA;  the front seat. In a flat spin, the canopy, when it ejects, bobbles&#xA;  for an extra few hundredths of a second above the aircraft. That&#xA;  upsets the carefully engineered sequence because the guy in the back&#xA;  could then hit the canopy. That sequence made it into the movie.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.eyeworld.org/printarticle.php?id=6600&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="7384" LastEditorUserId="7384" LastEditDate="2016-11-06T15:44:14.410" LastActivityDate="2016-11-06T15:44:14.410" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12829" PostTypeId="2" ParentId="12823" CreationDate="2015-02-21T13:58:16.740" Score="1" Body="&lt;p&gt;Not a perfect correlation with the Top Gun scenario, but somewhat relevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR72-26.pdf&quot; rel=&quot;nofollow&quot;&gt;mid-air collision&lt;/a&gt; between an F-4B Phantom and a DC-9 in 1971 highlighted an already known issue with the F-4's ejection system.  As ejecting into a closed canopy is less than desirable, an electrical interrupt was designed into the circuit to prevent actuation if the canopy was closed.  On the F-4 with its split canopy design, the pilot's canopy would often not unlock if the RIO ejected first, thereby trapping the pilot inside the aircraft.  Modifications to the fleet were already underway but the aircraft in question had not received them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So although this system was designed to avoid ejecting into the canopy, it led to the pilot's death anyway.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-02-21T13:58:16.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12830" PostTypeId="1" AcceptedAnswerId="13141" CreationDate="2015-02-21T16:54:52.543" Score="4" ViewCount="15753" Body="&lt;p&gt;I was looking on YouTube at crew training videos. One door caught my attention for a Qantas 767. This door was completely electric and slid up and into the fuselage above, instead of out and to the side like most ones I've seen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is how many different door mechanisms are there on commercial airliners and what are the benefits/disadvantages of each?&lt;/p&gt;&#xA;" OwnerUserId="7373" LastEditorUserId="65" LastEditDate="2015-02-21T22:40:30.813" LastActivityDate="2016-06-02T02:23:53.547" Title="What are the differences in door types in a commercial airliner?" Tags="&lt;airliner&gt;&lt;commercial-operations&gt;&lt;boeing-767&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12831" PostTypeId="2" ParentId="3871" CreationDate="2015-02-21T18:22:42.287" Score="1" Body="&lt;p&gt;For VMC approaches, just fly whatever tracks the extended centerline.  There should be no need to look at your HSI, heading bug, etc. other than to make sure you're landing on the correct runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For IMC approaches, take the crosswind and divide it by the number of miles per minute you're traveling.  You find this by dividing your TAS by 60 or just using your mach number.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Miles/Minute = MachNumber * 10&#xA;OR&#xA;Miles/Minute = TAS / 60&#xA;&#xA;Drift correction = Crosswind / (MilesPerMinute)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This will get you in the general ballpark.  What you should do is then bug this heading and see how it's working for you.  If the localizer is swinging one way or the other, then make a 1-2 degree correction to avoid chasing.  Rebug this heading and see how that adjustment works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or just use the flight director...&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-02-21T18:22:42.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12832" PostTypeId="1" AcceptedAnswerId="12833" CreationDate="2015-02-21T22:43:00.340" Score="64" ViewCount="64217" Body="&lt;p&gt;Why does the Boeing 787 nacelle have this unique shape at the exhaust:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://i296.photobucket.com/albums/mm184/Cheat11/787engine.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HtsVp.jpg&quot; alt=&quot;Boeing 787 Engine Nacelle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't seen it on any other airplanes, does it serve an aerodynamic purpose or help engine efficiency or is it just to look pretty?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="524" LastEditDate="2015-08-10T16:09:43.180" LastActivityDate="2016-06-24T07:45:53.867" Title="Why does the Boeing 787 engine nacelle exhaust have such an unusual shape?" Tags="&lt;jet-engine&gt;&lt;noise&gt;&lt;boeing-787&gt;&lt;nacelle&gt;&lt;aeroacoustics&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12833" PostTypeId="2" ParentId="12832" CreationDate="2015-02-21T23:25:50.920" Score="56" Body="&lt;p&gt;Well, it does look pretty, doesn't it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing wanted to reduce the noise generated because of &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_blast&quot;&gt;jet blast&lt;/a&gt; of the engines. Many airports around the world are implementing new noise regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;http://www.boeing.com/news/frontiers/archive/2005/december/ts_sf07.html&quot;&gt;mentioned by Boeing&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To combat the sound of jet-blast from the rear of the engine, Boeing,&#xA;  General Electric, and NASA developed serrated edges called chevrons&#xA;  for the back of the nacelle and the engine exhaust nozzle. The&#xA;  chevrons reduce jet blast noise by controlling the way the air mixes&#xA;  after passing through and around the engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The acoustic liners and chevrons are such effective noise suppressors&#xA;  that several hundred pounds of sound insulation may be eliminated from&#xA;  the fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As NASA was involved, &lt;a href=&quot;http://www.nasa.gov/topics/aeronautics/features/bridges_chevron_events_prt.htm&quot;&gt;they state&lt;/a&gt; &lt;em&gt;(my paraphrasing)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Chevrons are the sawtooth pattern seen on the trailing edges of some&#xA;  jet engine nozzles. &lt;strong&gt;As hot air from the engine core mixes with cooler&#xA;  air blowing through the engine fan, the shaped edges serve to smooth&#xA;  the mixing, which reduces turbulence that creates noise.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... The new Boeing 787 is among the most modern jets relying on&#xA;  chevrons to reduce engine noise levels. It sports chevrons on the&#xA;  nacelles, or fan housings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-02-21T23:25:50.920" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12834" PostTypeId="2" ParentId="12832" CreationDate="2015-02-21T23:51:30.743" Score="22" Body="&lt;p&gt;Actually, there were similar tricks used on Boeing aircraft before to reduce jet noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Conway&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce Conway&lt;/a&gt; (as used on the Boeing 707) had a scalloped exhaust which improved jet mixing and reduced exhaust noise. Since the Conway was also the first operational bypass engine, the lower exhaust speed of this design helped to reduce noise already. At the time of development the engineers expected the engine to be installed in wing roots, and the bypass ratio was only 0.25, however. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ggJbH.jpg&quot; alt=&quot;Rolls-Royce Conway rear view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the JTD-8 of the Boeing 737-100 used a similar silencer design:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/q1fp3.gif&quot; alt=&quot;JTD-8 engine cutaway view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases, the idea is to increase the surface between the hot, fast exhaust gas and the ambient air and to stretch out the &lt;a href=&quot;http://www.nasa.gov/topics/aeronautics/features/bridges_chevron_events.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;noise-intensive mixing process&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/questions/11884/do-nacelles-around-aircraft-engines-helps-in-reducing-the-engine-sound&quot;&gt;this question&lt;/a&gt; for more information.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-10T09:32:10.713" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12835" PostTypeId="2" ParentId="12832" CreationDate="2015-02-22T02:18:21.920" Score="50" Body="&lt;p&gt;I think both answers are correct, but I would like to spend some time describing the phenomena that chevrons try to reduce so that I can complement the answers already provided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what is happening in an engine? We have a hot gas at high speed leaving the engine core, and another gas at higher speed than the external air but much slower than the core, on top, and we have got the external airflow. Actually I am missing one that I will explain later on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, so between airflows with different properties (especially different speed) there is a layer where both airflows mix to create a different one with average properties (saying average is a simplification), the mix in a region called &quot;mixing layer&quot;. Unfourtunately, in typical engines, the way both layers mix is turbulent. Here is a typical image of a simulation of a mixing layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1BTVT.jpg&quot; alt=&quot;Enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This turbulent mixing creates sound. Actually is easy to see a similar phenomena in a flute. If you open it, you can see that when you blow you are introducing air that reaches a cavity where sound is produced (actually, there is another phenomenon, resonance, but I would like to illustrate that turbulence creates sound). Another example is when you wave a sharped object in air (like a blade); if you do it quickly enough, you will hear a sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That exact phenomenon happens around engines, but the sound is louder. Why? Because the difference between speeds is really high. A glider seems silent although the wings act as blades... but the difference in speed is not so high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what we know now is that the smaller the difference, the smaller the turbulence, the quieter the sound. Those chevrons you see in Boeing 787 actually have that objective. They are actually creating another layer of fluid at a intermediate speed between the air passing the external part of the engine (fan secondary flow) and the external flow, so that the jump of properties is smaller, turbulence gets reduced and sound is quieter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to show you the flows in an engine I took your photo and introduced some arrows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VmhR0.png&quot; alt=&quot;Enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the blue air coming for the external part of the nacelle mixes with the air coming from the fan (red arrow). Having the chevrons means that some parts are mixed earlier than others, creating positive distortion in the mixing layer like &quot;creating a third flow&quot;. The green arrow shows the air from the engine core, but there is another air flow between engine core and the fan, the violet arrow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is shown in the previous answers for Conway and JTD-8 engines are devices using the same principle, but they are actually not the same. In previous jet engines there was not a big secondary flow from the fan as nowadays and the mixture was directly between engine core and external flow, so it is the same principle, but the huge difference between speeds created the need of a more aggressive mixture. This device is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Hush_kit&quot; rel=&quot;noreferrer&quot;&gt;hush kit&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally to answer your question, there is no aerodynamic benefit; there is a penalty. The benefit is aeroacoustic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an indirect benefit, though: The amount of acoustic damping material needed to get the cabin quiet enough is reduced. That saves weight, and therefore fuel.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="1875" LastEditDate="2015-03-11T06:56:01.907" LastActivityDate="2015-03-11T06:56:01.907" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12836" PostTypeId="5" CreationDate="2015-02-22T02:26:20.293" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-02-22T02:26:20.293" LastActivityDate="2015-02-22T02:26:20.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12837" PostTypeId="4" CreationDate="2015-02-22T02:26:20.293" Score="0" Body=" a branch of acoustics that studies noise generation via either turbulent fluid motion or aerodynamic forces interacting with surfaces. Noise generation can also be associated with periodically varying flows" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2015-02-22T06:16:28.580" LastActivityDate="2015-02-22T06:16:28.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12840" PostTypeId="1" AcceptedAnswerId="12846" CreationDate="2015-02-22T17:04:48.263" Score="18" ViewCount="5062" Body="&lt;p&gt;As far as I can tell, the following factors all contributed to &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;this crash&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pitot tubes susceptible to ice crystal blockage&lt;/li&gt;&#xA;&lt;li&gt;Crew not aware that they can stall the airplane due to &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_control_modes#Alternate_law&quot;&gt;alternate law&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;No return to normal law after reliable speed information was available to the flight computers&lt;/li&gt;&#xA;&lt;li&gt;&quot;Unlinked&quot; sidesticks which allow the pilots to command different inputs, unaware of what the other pilot is commanding&lt;/li&gt;&#xA;&lt;li&gt;Stall warning goes quiet when the airspeed is too low&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of these, the first factor (pitot tubes) was already in the process of being mitigated. What about the other factors though? Were the onboard systems modified in any way to fix these shortfalls?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm no expert but it seems like at the very least that the following would help:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the stall warning didn't stop, but instead changed into an even more ominous &quot;you're now tumbling down at less than 60 KIAS&quot; warning. &lt;/li&gt;&#xA;&lt;li&gt;Also, given how extremely rare alternate law appears to be, it might not be out of order for the airplane to announce that it is now very much possible to stall the plane by pulling up (in actual words).&lt;/li&gt;&#xA;&lt;li&gt;Finally, it sounds like the unlinked nature of the sidesticks was a big part of the problem; are there good reasons to leave them unlinked in future designs?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some context:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Wikipedia article about the crash&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.webcitation.org/63mlsUX81&quot;&gt;CVR transcript and comments&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2194" LastEditorUserId="3201" LastEditDate="2016-01-30T21:47:10.733" LastActivityDate="2020-10-21T08:31:29.913" Title="What improvements did Airbus make as a result of the Air France 447 accident?" Tags="&lt;safety&gt;&lt;aircraft-systems&gt;&lt;airbus&gt;&lt;af447-accident&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12842" PostTypeId="1" AcceptedAnswerId="12845" CreationDate="2015-02-22T21:18:50.290" Score="4" ViewCount="936" Body="&lt;p&gt;Recently it has been discovered that turbercles present in fins from whales are actually providing hydrodynamic benefit for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As well, it has been proposed that this effect &lt;a href=&quot;http://www.gizmag.com/bumpy-whale-fins-set-to-spark-a-revolution-in-aerodynamics/9020/&quot; rel=&quot;nofollow noreferrer&quot;&gt;will provide&lt;/a&gt; benefit for airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5eW9G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my perspective I can see strong difficulties to see this design able to improve current leading edges, as well, is a design working in water, in a lower Reynolds environment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is actually three:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the aerodyamic (or hydrodynamic) mechanism and benefit that these turbercle provide?&lt;/li&gt;&#xA;&lt;li&gt;How applicable is that to the airplane industry as proposed in several publications? (first thing I see difficulties is the existance of high lift slats and compatibility with these turbercles, probably more applicable to tails).&lt;/li&gt;&#xA;&lt;li&gt;Which are the potential drawbacks of this design?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-02-22T22:16:38.963" Title="How turbercle wings could generate aerodynamic advantage?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12844" PostTypeId="2" ParentId="838" CreationDate="2015-02-22T21:37:07.110" Score="24" Body="&lt;p&gt;The wings of the Boeing 787 are so flexible because its carbon fiber material can be stretched more, and the high aspect ratio of 11 will magnify this effect. In flight, all you will feel is less shaking due to gusts, because the wing will dampen load changes more effectively. On the ground, the wing might have less tip clearance, because less in-built dihedral is needed - the rest is supplied by the wing's elasticity in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The influence on performance is slightly negative, but this is a very weak effect. It can be compared to the rolling resistance of a stiff bicycle versus one with a spring-loaded frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of bending for a given bending moment depends on three factors:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Wing span: A given curvature of the wing due to bending at the wing root will cause a tip displacement which is proportional to the distance of that tip from the root.&lt;/li&gt;&#xA;&lt;li&gt;Spar heigt: This curvature grows with the inverse of the square of the spar height. A lower relative thickness of the wing will produce more bending.&lt;/li&gt;&#xA;&lt;li&gt;Spar material: The &lt;a href=&quot;http://en.wikipedia.org/wiki/Young&amp;#39;s_modulus&quot;&gt;Young's modulus&lt;/a&gt; of the material describes how much it stretches for a given stress. More important, however, is the elastic elongation at yield stress. Carbon fiber has a higher Young's modulus than aluminium, but is elastic until rupture, so it can be stretched more and produces more bending at yield stress.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The numbers: The Young's modulus of aluminium is fairly constant for a wide range of alloys and normally 70,000 MPa or N/mm². The modulus of graphite fibers depends on their manufacturing process and varies between 200,000 and 700,000 MPa or N/mm². However, this value cannot be compared directly to that of aluminium. The final modulus of the composite depends on fiber orientation and resin content.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is safe to assume that Boeing (or more precisely, Mitsubishi Heavy Industries) uses a modern, high-strength fiber like &lt;a href=&quot;http://www.hexcel.com/resources/datasheets/carbon-fiber-data-sheets/im7.pdf&quot;&gt;IM7 (pdf)&lt;/a&gt; (IM stands for intermediate modulus), which has a modulus of 276,000 MPa. It is also safe to assume that most of the fibers are oriented in span direction, so they can contribute fully to taking the bending loads. If we assume a conservative fiber content of 60%, the resulting modulus of the spar material should be 164,000 MPa. However, the spar is not a discrete component, but part of the wing box which also has to take torsion loads. While Aluminium is an &lt;a href=&quot;http://en.wikipedia.org/wiki/Isotropy&quot;&gt;isotropic&lt;/a&gt; material (it has the same properties in all directions), CFRP is highly anisotropic, and adding torsional strength will require additional fibers in other directions. Consequence: The effective modulus of the wing box in bending direction might be as low as 110,000 MPa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, what counts is how much material is there to carry the bending loads. Here the yield stress of the material comes into play: The more stress a material can tolerate before it shows plastic deformation, the less of it is needed to carry a given bending moment. To arrive directly at the maximum deformation, it is enough to look at the maximum elastic strain. With IM7, this is 1.9%, and with high-strength &lt;a href=&quot;http://www.kaiseraluminum.com/wp-content/themes/kac/files/alloy-7068-brochure.pdf&quot;&gt;7068 aluminium (pdf)&lt;/a&gt;, it is less than 1% before the material suffers permanent elongation. This means that, even though CFRP is stiffer than aluminium, it can be loaded more and will stretch more before it reaches its limits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-02-23T12:37:05.050" LastActivityDate="2015-02-23T12:37:05.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12845" PostTypeId="2" ParentId="12842" CreationDate="2015-02-22T22:16:38.963" Score="11" Body="&lt;p&gt;No, please, not another revolution of how we build airplanes again!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The linked article mentions two guys who pose as the discoverers of humps on whale flipper leading edges. What precisely have generations of marine biologists overlooked before?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the humps: They produce a 3D flow pattern close to the leading edge which will help the flow to transition to a turbulent boundary layer more quickly. This is helpful at high angle of attack at intermediate Reynolds numbers (around 1 Mio) and will make the whales more maneuverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not to say that it will help any existing aircraft. Had nature given the whales the opportunity to integrate slats and double-slotted flaps into their flippers, they sure would have done so. This will help much more to increase maximum lift. Also, typical aircraft Reynolds numbers are much higher than those on whale flippers, and there turbulent transition is very quick. Right now, most efforts center on delaying this transition to reduce friction drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swept wings will see a massive drag increase if this sort of leading edge is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;tubercles&quot; are a very specific form of turbulators and optimized for a narrow application. In other words, don't invest in this WhalePower company!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-02-22T22:16:38.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12846" PostTypeId="2" ParentId="12840" CreationDate="2015-02-22T22:22:40.313" Score="9" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;What improvements did Airbus make as a result of the Air France 447 accident?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The official report has a section headed&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h2&gt;5 - CHANGES MADE FOLLOWING THE ACCIDENT&lt;/h2&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;h3&gt;5.2 Airbus&lt;/h3&gt;&#xA;&lt;p&gt;Review of the “Unreliable speed indication” procedure&lt;/p&gt;&#xA;&lt;p&gt;Flight Operations Telex (FOT) of 9 September 2009 recommending, at the next recurrent&#xA;training course, a session on the simulator at high altitude in normal and alternate law&#xA;including:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Manual aeroplane handling,&lt;/li&gt;&#xA;&lt;li&gt;Carrying out the UNRELIABLE SPEED INDICATION / ADR CHECK PROC procedure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Most of the changes were carried out by other parties, Air France, EASA, etc.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;If the stall warning didn't stop, but instead changed into an even more ominous &amp;quot;you're now tumbling down at less than 60 KIAS&amp;quot; warning.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Opinion: If the computers have decided they don't know what the heck is happening, it's probably a bad idea for them to make something up at random to shout at the crew. If the computers always know best, they should just probably shut-up, activate the cockpit wrist-restraints and fly the plane.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;it might not be out of order for the airplane to announce that it is now very much possible to stall the plane by pulling up (in actual words).&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Wild guess: Maybe this would help but not when the PF is already ignoring stall warnings and determinedly pulling up almost continuously. Generally less is more when the crew are likely to be confused and overwhelmed. There's probably a hundred things you can more easily accidentally do when you are flying in alternate law and when you are in alternate law you may not have time to patiently wait and listen whilst the computers enumerate them all to you.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;the unlinked nature of the sidesticks was a big part of the problem; are there good reasons to leave them unlinked in future designs?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So that the pilots can engage in wrestling matches? Yes, it seems there needs to be an even clearer indication of conflicting inputs but I'm not sure if mechanical feedback is necessarily the best method. Pilots are already supposed to be trained and tested on clear handover of control.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-22T22:22:40.313" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12848" PostTypeId="2" ParentId="6348" CreationDate="2015-02-22T23:06:24.037" Score="0" Body="&lt;p&gt;A famous reference is: 'Aerodynamics, selected topics on the light of their historical development', by Theodore von Karman. There's also a site: Desktop.Aero offering a digital textbook on applied aerodynamics, but as I'm not engineer, I never went beyond cover page. NASA/NACA Cranfield database contain lots of aviation related papers since very early, a link to a list exists in Rotaryeng.net site: NACA UK Archive results page&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-02-22T23:06:24.037" CommentCount="0" CommunityOwnedDate="2015-02-22T23:06:24.037" ContentLicense="CC BY-SA 3.0" />
  <row Id="12849" PostTypeId="2" ParentId="2999" CreationDate="2015-02-22T23:18:14.703" Score="1" Body="&lt;p&gt;I was told by a pilot that he flew for some time over the Pirineos mountains with a Spanish version of Junkers Ju-52 with engines idling, and maintaining height on a hot air ascending current, as sailplanes do, but probably it's an exception rather than any rule. &#xA;Literature about Sud-Aviation's Caravelle discussed also a 'gliding' flight of some hundred kilometers, starting at a very high altitude and in special experimental conditions, taking place before 1964. &#xA;A pilot won an award after landing a jet airliner with engines not running; when he was approaching an abandoned airstrip, he realized that height was too high, he put the airplane in a crossed control surfaces pattern to slide on the side and lose altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Others flew for a while a DC-3 in inverted flight from Gando, in Gran Canaria, to Lanzarote, also in the Canary Islands, just to find on landing that engine nacelles were covered by oil, as the DC-3 engines lacked an inverted flight crankcase or 'dry' oil carter. One of the men in this DC-3 flight, Fernando Aymerich-Alix, bellied a Sabre or Super-Sabre jet fighter in a plowed field, on the premises that he felt the indications of fuel tank gauges were inaccurately high, and he will soon run out of fuel. When reaching the ground, the somehow abundant fuel actually left in the tanks spread as a shower all over the airplane and the place, he was lucky the fuel didn't catch fire. He died first half of December 2017&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2017-12-23T15:13:21.633" LastActivityDate="2017-12-23T15:13:21.633" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12850" PostTypeId="2" ParentId="2360" CreationDate="2015-02-22T23:22:11.283" Score="1" Body="&lt;p&gt;Blanik L-13 and Scheibe Bergfalke sailplanes had swept-forward wings, it seems it helps in adding freedom in setting center of gravity respect to the pressure center and pilots placement. Advantages of forward swept wings may be mainly in the low speed range, takeoff and landing. &#xA;I'm not too sure about Ju-287 being a failure, there are reports it reached 1'000 km/ h in the Soviet hands, good for a bomber, but developing the concept was discontinued, they may have found some heavy problems. A tailless US airplane of the late 40s used this arrangement, NASA/ NACA, Cranfield repository  has documents about it, also YouTube videos exist&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2016-12-28T11:21:28.977" LastActivityDate="2016-12-28T11:21:28.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12852" PostTypeId="1" AcceptedAnswerId="12854" CreationDate="2015-02-23T14:15:05.580" Score="22" ViewCount="18993" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/1960/3170&quot;&gt;How are jet engines started?&lt;/a&gt; says that engines must be started from bleed air, which can come from the APU, another engine, or a huffer cart, or from windmilling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I understand, APUs are also jet engines. How are they started? In the air, they must be able to start when both engines are out, so are they able to windmill start? On the ground, can they connect to a huffer cart?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2017-09-26T16:35:12.653" Title="How are APUs started?" Tags="&lt;jet-engine&gt;&lt;apu&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12853" PostTypeId="2" ParentId="12852" CreationDate="2015-02-23T14:27:21.520" Score="7" Body="&lt;p&gt;APUs are smaller jet engines that don't have that much rotational inertia that must be developed before they can self-sustain themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a simple electric starter-motor on battery power that auto disengages once it is running is enough.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-02-23T14:27:21.520" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12854" PostTypeId="2" ParentId="12852" CreationDate="2015-02-23T15:30:48.067" Score="37" Body="&lt;p&gt;APUs are like small jet engines, small enough to be started electrically. So you would use the power of the battery or an electric ground power cart to spin up the APU by its electric starter motor, and then introduce fuel into it once its spinning fast enough, just like a jet engine is started. Depending on the design, the electric motor will then either act as a generator to supply electrical power back to the aircraft or decouple when a separate generator is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The APU will spin up, and besides spinning the electric generator, some pressurized air will be 'stolen' from its compressor to supply &quot;bleed air&quot; for engine starting, the air conditioning packs, etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Big APUs like on the Boeing 777 have actually two methods of starting: They have both an air-driven and an electric driven starter motor. The method of operation is as follows: When the APU is started with the engines off, electrical power from battery or ground connection is used. After the flight, the APU will be restarted before the main engines are turned off. In that case, the APU will be started by the air-driven motor rather than the electric motor, with pressurized air supplied by the still-running main engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT to answer question in comment:&#xA;Depending on size, the APU will take something between 30seconds and 2 minutes to start. The big APU of the 777 will deliver electrical power after 2 minutes or so, small units you are likely to find on regional jets can do that after perhaps 45 seconds. Then, it takes an additional 2-4 minutes until you can extract bleed air from it. That is because taking air from the compressor increases the exhaust gas temperature of the APU, and you want the APU to warm up evenly. The same is true for the shutdown process: You close the bleed-air valve and then let the APU continue to run for another two minutes or so to cool down, then shut it off completely. This lowers the thermal stress on the unit. On modern planes like the 777 this process is automated: You turn the APU selector switch to OFF and that will close the bleed air valve, initiate a 2 minute cooldown period, and eventually turn off the APU completely. The only way to shut it down immediately is in fact the APU FIRE handle.&#xA;So, you will turn the APU on typically while you are taxiing in after landing. Because of course you want it to be up and running and ready to take over the air conditioning by the time you are at the gate.&#xA;Some APUs like those found on the MD-80s have two settings for bleed air extraction: NORM and ECON. ECON takes less bleed air, thus not increasing the exhaust gas temperature of the APU too much. On particularly hot days, using the APU bleed in ECON might help not overheating the APU if it is to be used for an extended period of time.&lt;/p&gt;&#xA;" OwnerUserId="577" LastEditorUserId="577" LastEditDate="2015-02-25T17:54:14.390" LastActivityDate="2015-02-25T17:54:14.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12855" PostTypeId="2" ParentId="2360" CreationDate="2015-02-23T16:45:42.860" Score="16" Body="&lt;p&gt;Advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing spar carry-through can be placed aft of the cabin, so cabin height can be increased. This is important for business-jet sized aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The boundary layer at the tips is not affected by the inner wing. Controllability can be maintained up to stall.&lt;/li&gt;&#xA;&lt;li&gt;Aeroelastic effects will increase control commands. This makes for a very responsive airframe.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, they are directly connected to these disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Stall will happen inboard first, which will result in a pitch-up. If the tail cannot compensate, the stall is unrecoverable.&lt;/li&gt;&#xA;&lt;li&gt;The aeroelastic effects will encourage flutter. If flutter speed is found to be too low, the wing needs to be made stiffer, resulting in a weight increase.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These two disadvantages easily outweigh the advantages for most designs. The first forward swept design, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Ju_287&quot; rel=&quot;noreferrer&quot;&gt;Junkers 287&lt;/a&gt;, needed a massive, wrought wing carry-through for stiffness. Handling was great, but performance overall was poor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/chvba.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/chvba.jpg&quot; alt=&quot;Ju-287 with tufted wings and rockets below the wing engines&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Ju-287 with tufted wings and rockets below the wing engines. The tripod ahead of the vertical holds a faired camera for in-flight observation of the tufts. (picture &lt;a href=&quot;http://3.bp.blogspot.com/_wExpT4-LAPw/TUhSdUHdkSI/AAAAAAAAAdQ/yiVNgQ9Hibc/s1600/Junkers+Ju-287.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If combined with a T-tail, the aft position of the root of a forward swept wing will ensure that the tail is in the wake of the wing root at a high angle of attack, which can result in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8022/what-is-a-deep-stall-and-how-can-pilots-recover-from-it&quot;&gt;deep stall&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best forward-swept wings can be found in nature: Birds will sweep their wing tips forward if they want to pitch up and create lots of lift. Especially for short landings the forward-swept wing is ideal when the legs are on the ground at the time of wing stall.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-11-18T23:33:02.163" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12856" PostTypeId="1" AcceptedAnswerId="12857" CreationDate="2015-02-23T18:30:10.507" Score="8" ViewCount="324" Body="&lt;p&gt;The SID chart for Mannheim, Germany (EDFM) runway 27 has segments to OLIVI are not defined in terms of any navigational aids but simply specify a track.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How am I supposed to fly these accurately? And more to the point, how am I supposed to determine that I'm over KOSAX? Dead reckoning? You might think that the SID requires GPS or other RNAV equipment, but there is another chart for that (which is virtually identical, but uses GPS-fix symbols instead of intersections).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;KOSAX is also not shown on the Lower Enroute chart, which might otherwise have helped to determine its location.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-02-24T08:22:17.310" LastActivityDate="2015-02-24T08:22:17.310" Title="How am I supposed to track to KOSAX on the OLIVI 4W out of EDFM?" Tags="&lt;instrument-flight-rules&gt;&lt;sid-star&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12857" PostTypeId="2" ParentId="12856" CreationDate="2015-02-23T19:37:23.247" Score="8" Body="&lt;p&gt;The textual description for OLIVI 4W is:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;OLIVI FOUR WHISKEY&#xA;On track 256° to 6.0 DME MND; RT, on track 333° to KOSAX;&#xA;LT, on track 294° to OLIVI.&#xA;Climb with 7.9% (480 ft/NM) or more until passing 3000,&#xA;then climb with 6.4% (390 ft/NM) or more until passing 6000.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;However, the remarks section holds the answer:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;1. PDG 7.9% (480 ft/NM) due to obstacles.&#xA;   If unable to comply, request alternative instruction by ATC.&#xA;2. PDG 6.4% (390 ft/NM) due to airspace structure.&#xA;3. After 6.0 DME MND BRNAV equipment necessary.&#xA;4. During activity of ED-R 205 (TRA) MAX FL80.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MkI0s.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Note &quot;3. After 6.0 DME MND BRNAV equipment necessary.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BRNAV in this case means &quot;Basic RNAV&quot;, which is essentially a form of RNAV equipment, but with less stringent certification requirements compared to normal IFR RNAV equipment.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="19" LastEditDate="2015-02-23T19:49:29.560" LastActivityDate="2015-02-23T19:49:29.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12858" PostTypeId="1" AcceptedAnswerId="12860" CreationDate="2015-02-23T20:09:37.530" Score="6" ViewCount="366" Body="&lt;p&gt;Often when listening to ATC (commonly Dublin), when an ATP requests push and start, the controller will reply, &quot;You have missed your pushback window&quot;, and/or ask the pilot to call their company or handler to &quot;file a delay&quot; or &quot;update your flight plan with your off-blocks time&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have two questions about this but I expect the same answer answers both.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Why is it necessary to re-file the plan, rather than simply activating the flight plan with the actual departure time?&lt;/li&gt;&#xA;&lt;li&gt;Why is it necessary for the pilot to change to the airline's frequency, chat them up, change back, and then wait for the electronic flight plan to be updated, rather than talking to the controller directly?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-02-23T21:18:49.907" LastActivityDate="2015-09-28T10:03:22.677" Title="Why do airliners have to file delays through their handlers?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;flight-plans&gt;&lt;flight-schedules&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12859" PostTypeId="1" AcceptedAnswerId="12904" CreationDate="2015-02-23T20:24:44.590" Score="4" ViewCount="4539" Body="&lt;p&gt;After reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/6411/does-a-prone-position-for-the-pilot-minimize-g-force-effects&quot;&gt;this question&lt;/a&gt; and the &lt;a href=&quot;http://www.dragondoor.com/articles/power-breathing-the-jet-jock-style/&quot; rel=&quot;nofollow noreferrer&quot;&gt;linked article&lt;/a&gt;, I had some more questions about G-Forces on pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The average, fit aviator has about a 3g &quot;naked&quot; limit, which comes&#xA;  from automatic tightening of blood vessels forcing blood to the brain.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm a private pilot, with no training with G-forces.  I'm average fitness (maybe even a little below average).&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the big 40th Birthday, I went to the &lt;a href=&quot;http://www.skycombatace.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sky Combat Ace experience&lt;/a&gt;, doing simulated dog-fights in Extra 330LCs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instructors said that both my brother and I pulled in excess of 7G. (with no G-suits or anything beyond some grunting).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not so sure I believe that now.  Were they blowing smoke to give us a fun experience?&#xA;Or could I have credibly pulled 7G for 10-20 seconds without prior experience?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-25T21:21:04.903" Title="How does an inexperienced pilot handle G-Forces?" Tags="&lt;human-factors&gt;&lt;g-forces&gt;&lt;dogfighting&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12860" PostTypeId="2" ParentId="12858" CreationDate="2015-02-23T20:27:28.797" Score="9" Body="&lt;p&gt;Since you mention Dublin, I am going to give an answer that describes the situation in Europe. Other parts of the world may have different procedures, although I believe they will be similar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually a flight plan must be activated within a given time window to ensure that there is enough capacity (airspace, ATC staffing, departure &amp;amp; arrival airport constraints) along the route to handle the flight. If the flight is not departing with this 'slot' a new flight plan needs to be requested and approved by the &lt;a href=&quot;https://www.public.nm.eurocontrol.int/PUBPORTAL/gateway/spec/index.html&quot;&gt;Network Manager Operations Centre&lt;/a&gt; (NMOC) (Previously called Central Flow Management Unit (CFMU)). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller is not responsible for filing flight plans and cannot be tasked with doing the paperwork for the crew. The crew therefore needs to contact their handler or flight operation centre to refile a flight plan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NMOC will reassess the flight plan and verify that there is capacity along the planned route to handle the flight. If there isn't, the flight may need to be planned along another route or an additional slot delay will be given. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-02-23T20:27:28.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12861" PostTypeId="2" ParentId="12859" CreationDate="2015-02-23T22:43:02.210" Score="2" Body="&lt;p&gt;A &lt;a href=&quot;http://www.bruceair.com/aerobatics/aerobatics.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;normal acrobatic ride&lt;/a&gt; experiences 3-4 G's for a few seconds. Competition acrobatic pilots will pull up to 5 Gs for 2-3 seconds, which is risky. It is difficult to do more than this in a piston-powered aircraft. 5 Gs for more than 5 seconds will present a significant risk of a blackout or loss of consciousness in an inexperienced person. From a textbook on aeronautical medicine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/12zsn.png&quot; alt=&quot;G-force table&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-25T21:21:04.903" LastActivityDate="2015-03-25T21:21:04.903" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12863" PostTypeId="1" AcceptedAnswerId="12865" CreationDate="2015-02-24T02:53:12.450" Score="25" ViewCount="21254" Body="&lt;p&gt;As a kid, I remember going to the cockpit of a plane with my mom (I believe the airline was &lt;a href=&quot;http://en.wikipedia.org/wiki/AOM_French_Airlines&quot;&gt;AOM French Airlines&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this still possible now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the answer might differ with different airlines/countries, I'm mostly interested in European and Asian airlines/countries, specifically Japanese.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some specific regulations for international flights, or does it depends on departure/arrival locations?&lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="65" LastEditDate="2015-02-24T16:24:02.503" LastActivityDate="2015-02-24T21:08:42.587" Title="Can a passenger request to visit the cockpit during a flight?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;pilots&gt;&lt;cockpit&gt;&lt;regulations&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12864" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T02:56:15.537" Score="6" Body="&lt;p&gt;Usually the cockpit is restricted during any phase of flight besides boarding/de boarding. This is usually the case with major airlines with any destination in Europe, or the U.S., not sure abut Asia though&lt;/p&gt;&#xA;" OwnerUserId="7373" LastActivityDate="2015-02-24T02:56:15.537" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12865" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T04:43:08.373" Score="18" Body="&lt;p&gt;This stopped after the World Trade Center attacks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might be able to get a kid in briefly before the plane takes off.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-24T04:43:08.373" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="12866" PostTypeId="1" AcceptedAnswerId="12881" CreationDate="2015-02-24T05:41:57.937" Score="16" ViewCount="1312" Body="&lt;p&gt;I was reading up on Appaero's new ADS-B OUT transponder and clicked over to the &lt;a href=&quot;https://www.appareo.com/aviation/ads-b/stratus-coverage-map/&quot; rel=&quot;noreferrer&quot;&gt;Stratus coverage page&lt;/a&gt; for some reason. Then I glanced at the map, and noticed something interesting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4YdpK.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Western Colorado is, well, ADS-B tower &lt;strong&gt;central&lt;/strong&gt;&lt;/em&gt;. What gives? Chicago and the northeast are close, but not nearly as dense.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="1696" LastEditDate="2015-02-24T15:54:24.060" LastActivityDate="2015-07-05T15:33:21.490" Title="Why are there so many ADS-B ground towers in western Colorado?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12867" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T08:52:09.300" Score="3" Body="&lt;p&gt;It's a &lt;em&gt;security and/or safety risk&lt;/em&gt; to allow any persons in the cockpit these days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow&quot;&gt;This accident&lt;/a&gt; happened as a pilot allowed his children to take control during flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With the autopilot active, Kudrinsky, against regulations, let the children sit at the controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've seen flight crashes, in which persons in the cockpit have interfered with the flight in one way or the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on these experiences, unauthorized persons in the cockpit is totally not allowed these days.&lt;/p&gt;&#xA;" OwnerUserId="7407" LastEditorUserId="65" LastEditDate="2015-02-24T14:34:18.637" LastActivityDate="2015-02-24T14:34:18.637" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12868" PostTypeId="2" ParentId="78" CreationDate="2015-02-24T09:09:02.043" Score="3" Body="&lt;p&gt;In addition to what DeltaLima answered, also remember that denser air means the isobars are closer together and that in turn means that if your altimeter reads correctly on the ground, the &lt;strong&gt;same baro-altitude gives you less clearance from terrain.&lt;/strong&gt; Some instrument procedures have minimal temperature for this reason.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-02-24T09:09:02.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12870" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T10:21:52.447" Score="8" Body="&lt;p&gt;Generally speaking, you will not get very lucky unless you are a pilot yourself and are carrying your license with you (and even then, this is airline dependent). If this is the case, you might even be able to ride in the jump seat for a portion of the flight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground a lot of pilots/cabin crew are friendly and would be happy to show you around. Use common sense though and ask to go after landing for the best chance - before take off the crew will be quite busy with pre-flight checks.&lt;/p&gt;&#xA;" OwnerUserId="7409" LastActivityDate="2015-02-24T10:21:52.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12871" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T10:34:30.270" Score="3" Body="&lt;p&gt;About 30 years ago I did this during flight when I was a kid. These days I manage to do it for my daughter but only while boarding.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="65" LastEditDate="2015-02-24T14:29:08.873" LastActivityDate="2015-02-24T14:29:08.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12872" PostTypeId="2" ParentId="8851" CreationDate="2015-02-24T11:20:27.750" Score="3" Body="&lt;p&gt;The airfoil profile is also slightly different since, in the case of propellers, the goal is to push the air through. Therefore, the lift produced by the wing and felt by the shaft will produce torque that opposes the rotation. In the other case, the goal is extract energy from the flow going through the turbine. Thus, the lift force is in the opposite direction and helps the shaft rotation. Furthermore, more specific energy (as in per unit mass) can be extracted from the flow than injected into it. This is because, in turbines, the flow is going down the pressure gradient which has a stabilising effect. With a propeller, you're trying to push the flow through an adverse pressure gradient and this tends to enhance flow separation on your blades. Therefore, turbines tend to have higher loads and require thicker profiles.&lt;/p&gt;&#xA;" OwnerUserId="2855" LastActivityDate="2015-02-24T11:20:27.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12873" PostTypeId="1" AcceptedAnswerId="12874" CreationDate="2015-02-24T11:22:26.817" Score="7" ViewCount="819" Body="&lt;p&gt;Imagine multiple controllers talking on the same frequency would be a nightmare for pilots and other controllers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in real life how many controllers are there for each frequency? If there are more than one, how do they split the work load?&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-02-24T12:41:19.737" Title="How many controllers are there per frequency?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12874" PostTypeId="2" ParentId="12873" CreationDate="2015-02-24T11:29:38.210" Score="11" Body="&lt;p&gt;There is one frequency per sector and there can be two controllers per sector, one working the scope / talking to aircraft and one assisting with flight strips and coordination with adjacent sectors. If the sector does not require a second controller to coordinate and assist with flight strips, there will only be one controller doing all tasks single-handedly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, two sectors are combined and both frequencies are manned by the same controller, but this is only done in low-traffic times, where overlapping transmissions have a low probability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good and well-written source to understand how ATC sectors and split workload works is the AVWeb Series of &lt;a href=&quot;http://www.avweb.com/news/sayagain/index.html?page=7&quot; rel=&quot;nofollow noreferrer&quot;&gt;Say Again? by Don Brown&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this related question for more information:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/11754/572&quot;&gt;What is the maximum number of planes a controller can control?&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-02-24T12:41:19.737" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12875" PostTypeId="2" ParentId="8580" CreationDate="2015-02-24T12:26:10.883" Score="3" Body="&lt;p&gt;The range is calculated by this formula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$Range = 1.25 (√Ht + √Hr)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;'Range' - in nautical miles&lt;br&gt;&#xA;&lt;code&gt;Ht&lt;/code&gt; - height of transmitter in feet&lt;br&gt;&#xA;&lt;code&gt;Hr&lt;/code&gt; - height of receiver in feet&lt;/p&gt;&#xA;" OwnerUserId="2283" LastEditorUserId="65" LastEditDate="2015-02-24T14:19:40.130" LastActivityDate="2015-02-24T14:19:40.130" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12876" PostTypeId="1" AcceptedAnswerId="12882" CreationDate="2015-02-24T12:27:12.283" Score="13" ViewCount="4258" Body="&lt;p&gt;That is the case for aircraft operated by e.g. KLM. Some aircraft are named after birds, some after cities. Is that common for other airlines as well or something that only KLM does?&lt;/p&gt;&#xA;" OwnerUserId="7378" LastEditorUserId="15311" LastEditDate="2020-03-28T14:42:50.573" LastActivityDate="2020-03-28T14:42:50.573" Title="Why do certain airlines give names to their aircraft?" Tags="&lt;airline-operations&gt;&lt;aircraft-naming&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12877" PostTypeId="2" ParentId="12863" CreationDate="2015-02-24T12:29:51.130" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can I ask to go to the cockpit &lt;strong&gt;during&lt;/strong&gt; a flight ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course you can. The answer will be a firm &quot;No&quot; and you will be watched very closely by the cabin crew and any plainclothes security onboard until you land. It's possible the police will be waiting for you.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can I ask to go to the cockpit &lt;strong&gt;after&lt;/strong&gt; a flight ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course you can. If it's a longer stop the crew are often happy to show off their office. If it's the end of a 12 hour intercontinental flight with a bad-weather landing they might decline. &lt;/p&gt;&#xA;" OwnerUserId="2590" LastActivityDate="2015-02-24T12:29:51.130" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12878" PostTypeId="2" ParentId="12876" CreationDate="2015-02-24T12:47:18.003" Score="8" Body="&lt;p&gt;There are also other airlines which name their aircraft, e.g. Lufthansa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To understand where this comes from, I recommend reading the blogs below, excerpts quoted here for a quick intro.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.lufthansagroup.com/en/themen/aircraft-naming.html&quot; rel=&quot;nofollow&quot;&gt;Lufthansa | Aircraft Naming&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Lufthansa naming conventions as a sign of our time&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The &quot;Herborn&quot; brings the total number of aircraft named after German cities and states to over 300. This naming convention has a long tradition at Lufthansa. The first Lufthansa aircraft was named in 1960. The idea was to express the company's solidarity with its German homeland – not just with the major hubs and cities but also with the regions where a large portion of Lufthansa passengers and employees come from.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://blog.klm.com/every-plane-needs-a-name/&quot; rel=&quot;nofollow&quot;&gt;Meanwhile at KLM | Every Plane Needs A Name&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;KLM has always had a rather unique approach to naming its planes. It’s unclear who first came up with the idea of giving names to aircraft, but we do know that our first aircraft got its name in a completely different way than those in our current fleet. &lt;br&gt;&#xA;  KLM’s first Koolhoven actually had a nickname, “Dikke Dirk” (Fat Dirk), which was inspired by the last two letters of its registration, H-NADD, but also aptly described the unusually chubby fuselage of this aircraft type. “Dikke Dirk” was followed by “Piet Haas” (Peter Hare), because by then the Netherlands adopted the PH registration, which is how the Koolhoven registered PH-AES got the name “Piet Haas” (“haes” closely resembles “haas”, the Dutch word for “hare”). All this is much the same, I suppose, as people naming their car after the letters in its registration.&lt;br&gt;&#xA;  Let’s move on to the first “real names”. Not surprisingly, bird names were very popular. Vast flocks of bird names, in fact. Most KLM staff and aficionados are familiar with the “Uiver” (Stork), “Snip” (Snipe) and “Pelikaan” (Pelican), which all made legendary flights. The name “Uiver” certainly harks back to the era in which the plane was named, because most Dutch people nowadays would call a stork an “ooievaar”.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://blog.klm.com/who-thinks-up-aircraft-names-jesseyknows/&quot; rel=&quot;nofollow&quot;&gt;Meanwhile at KLM | Who Thinks Up Aircraft Names&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What do the “Borobudur”, “Museum Square” and “Blue Kestrel” have in common? They all crisscross the globe proudly displayed on KLM aircraft. But why do KLM aircraft have names? And who thinks them up?&lt;br&gt;&#xA;  &lt;br&gt;KLM is one of the few airlines that gives its aircraft names. And I have to admit that I was unable to find out why. What I do know is that our very first aircraft, a Koolhoven FK-33 acquired in 1925, was known as the “Dikke Dirk” (Fat Dirk). The aircraft did have an unusually broad waistline, but the name had more to do with the last letters of its registration: DD.&lt;br&gt;&#xA;  What are KLM’s aircraft named after?&#xA;  &lt;br&gt;&lt;br&gt;&#xA;  Airbus A330s: City Squares Worldwide&lt;br&gt;&#xA;  Boeing 737s: Birds&lt;br&gt;&#xA;  Boeing 777s: World Heritage Sites&lt;br&gt;&#xA;  Boeing 747s: World Cities&lt;br&gt;&#xA;  Boeing 747 Freighters: Ships of the Dutch East India Company (VOC)&lt;br&gt;&#xA;  Boeing 787-9 Dreamliners: Flowers&lt;br&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="572" LastEditorUserId="946" LastEditDate="2015-02-26T15:52:26.550" LastActivityDate="2015-02-26T15:52:26.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12880" PostTypeId="2" ParentId="9497" CreationDate="2015-02-24T15:50:03.707" Score="1" Body="&lt;p&gt;Just an addition to the previous answer, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While they may be legally able to get a medical cert and complete the training they may find it extremely difficult. Having vision in only one eye can have a drastic impact on depth perception and ones ability to observe motion. The human body can see distance, and motion (distance change over time) largely by triangulating objects from both eyes. If the loss in vision happened later in life many people are able to retain enough estimation ability to still be able to see and estimate motion and distance with ease. While I would advise him to give it a try he may find certain things very difficult and he should be prepared for that. I would also strongly advise an instrument rating in this case so as not to need to rely on vision all the time.     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-02-24T15:50:03.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12881" PostTypeId="2" ParentId="12866" CreationDate="2015-02-24T15:52:43.053" Score="18" Body="&lt;p&gt;As GdD commented, the cluster you noticed is not near Denver, but Montrose, CO. The reason for this cluster is &lt;a href=&quot;http://www.faa.gov/nextgen/programs/adsb/wsa/wam/&quot;&gt;Wide Area Multilateration (WAM)&lt;/a&gt; with ADS-B. This technique uses many sensors distributed around an area to provide better coverage in areas with mountainous terrain that blocks a single radar or ADS-B station. Western Colorado is one such area that experiences delays when ATC does not have sufficient radar coverage to support operations in inclement weather. &lt;a href=&quot;https://www.faa.gov/nextgen/snapshots/stories/?slide=14&quot;&gt;Montrose is one of the areas&lt;/a&gt; that the FAA is using to develop this technology. This &quot;constellation&quot; serves the following airports:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Gunnison-Crested Butte Regional (GUC)&lt;/li&gt;&#xA;&lt;li&gt;Montrose Regional (MTJ)&lt;/li&gt;&#xA;&lt;li&gt;Telluride Regional (TEX)&lt;/li&gt;&#xA;&lt;li&gt;Durango-La Plata County (DRO)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/documents/APNT/media/20120503_SURVEILLANCE_AND_BROADCAST_SERVICES_DEPLOYMENT_STATUS_GLEN_DYER_ITT_EXELIS.pdf&quot;&gt;this technical presentation&lt;/a&gt; about the WAM project, and &lt;a href=&quot;http://montrosecounty.granicus.com/MetaViewer.php?view_id=2&amp;amp;clip_id=232&amp;amp;meta_id=18071&quot;&gt;the lease for the tower sites&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, somewhat related, see this &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.recsearch/Recommendation.aspx?Rec=A-99-063&quot;&gt;NTSB safety recommendation&lt;/a&gt; regarding ADS-B coverage serving SAR needs after a crash near Montrose.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="3825" LastEditDate="2015-07-05T15:33:21.490" LastActivityDate="2015-07-05T15:33:21.490" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12882" PostTypeId="2" ParentId="12876" CreationDate="2015-02-24T17:25:10.220" Score="17" Body="&lt;p&gt;The practice of naming aircraft probably comes from the days of the flying boat, and the naval tradition of naming ships - &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_314_Clipper&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Pan Am Clippers&lt;/a&gt; had many named aircraft, and &lt;a href=&quot;http://www.panamair.org/aircraft/clippernames.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pan Am kept up the tradition into the Jet Age&lt;/a&gt;. Other airlines of the period had similar naming practices (I'm not sure who started it, but Pan Am's fleet was well known for it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a marketing tool telling folks they're flying on &quot;Clipper Emerald Isle from New York to Dublin&quot; may have been more attractive to passengers than &quot;Pan Am Flight 12345&quot; or N880PA. Particularly before the commoditization of air travel, when flying was still a new and novel form of transportation, having a connection back to familiar &quot;sailing&quot; metaphors may have helped get passengers on board and could help differentiate your service from another airline. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern airlines don't seem to push their aircraft naming as much as historic carriers did, but &lt;a href=&quot;https://aviation.stackexchange.com/a/12878&quot;&gt;as SentryRaven noted there are a few airlines that still name their ships&lt;/a&gt; - in fact Lufthansa paints their plane names onto the fuselage, though I'm not sure if they announce them to passengers.&lt;br&gt;&#xA;A skilled marketing department could build a brand around ship names, but I'm not aware of any airline doing so today.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-02-24T17:25:10.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12883" PostTypeId="2" ParentId="265" CreationDate="2015-02-24T18:13:58.007" Score="5" Body="&lt;p&gt;Magnetic direction and true direction are interchanged with the help of variation. Rule of thumb is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Variation west magnetic best ( more than true)  &lt;/li&gt;&#xA;&lt;li&gt;Variation east magnetic least ( less than true)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Or&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;MD + VAR EAST = TD&#xA;MD - VAR WEST = TD&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="2283" LastEditorUserId="65" LastEditDate="2015-02-24T19:09:16.263" LastActivityDate="2015-02-24T19:09:16.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12885" PostTypeId="1" AcceptedAnswerId="12886" CreationDate="2015-02-24T22:08:27.460" Score="48" ViewCount="23479" Body="&lt;p&gt;Before takeoff, during flight, before landing and for taxiing, pilots are given several instructions by ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they mentally remember all instructions? Or do they note them down somewhere such as in a notebook so that they do not forget?&lt;/p&gt;&#xA;" OwnerUserId="7418" LastEditorUserId="65" LastEditDate="2015-02-25T14:07:36.057" LastActivityDate="2017-07-05T17:05:08.743" Title="How do pilots manage to remember ATC instructions?" Tags="&lt;air-traffic-control&gt;&lt;pilots&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="12886" PostTypeId="2" ParentId="12885" CreationDate="2015-02-24T22:23:59.550" Score="51" Body="&lt;p&gt;It depends.  Some instructions are really simple and with a little practice, are very easy to remember.  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Runway 27 right, line-up and wait&#xA;Turn left heading 250, descend flight level 120.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Other ones will be so common, they are just remembered:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Taxi to Gate 1 via Alpha, Alpha 1, Lima 3, cross runway 24, hold short Delta.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;But this is where the danger creeps in.  It is possible, and has happened, that the crew &lt;strong&gt;think&lt;/strong&gt; they heard something but actually, the instruction was different today.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Taxi to Gate 1 via Alpha, Alpha 3, cross runway 24, hold short Delta.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The prudent crew will write it down.  &lt;a href=&quot;https://aviation.stackexchange.com/questions/9204/what-is-this-component-in-an-airbus-cockpit&quot;&gt;Large aircraft have tables&lt;/a&gt;, or boards clipped to the control column on which to write taxi clearances, complex airways clearances and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some large aircraft, many light aircraft and in helicopters, pilots might wear a kneeboard to write instructions on.  It is a minor advantage to me that I am left handed and as a helicopter pilot, this means that my kneeboard is on my left leg where I can easily write without taking my hand off the cyclic and having it right next to the collective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jHTJs.jpg&quot; alt=&quot;TSGT LANCE CHEUNG, USAF. - This Image was released by the United States Air Force with the ID DF-SD-01-07429&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://research.archives.gov/description/6514935&quot; rel=&quot;noreferrer&quot;&gt;TSGT LANCE CHEUNG, USAF. - This Image was released by the United States Air Force with the ID DF-SD-01-07429&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most instructions come in the same order, every flight.  For example, here is a simplified list.  This happens every time so the crew know what's coming next, what it will likely contain, and how to respond:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Clearance for the flight plan.&lt;/li&gt;&#xA;&lt;li&gt;Permission to start and push back. &lt;/li&gt;&#xA;&lt;li&gt;Taxi instructions.&lt;/li&gt;&#xA;&lt;li&gt;Departure instructions.&lt;/li&gt;&#xA;&lt;li&gt;Take off clearance.&lt;/li&gt;&#xA;&lt;li&gt;Hand-off from departure controller to area controller.&#xA;etc etc.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Note that any instruction which will cause the aircraft to change it's configuration or location must be repeated.  The controller then also gets to check they've got it right.  This includes things like speed, direction or altitude changes, taxi and departure instructions, frequency and squawk changes etc.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some words which are only ever used at certain times, e.g. &quot;takeoff&quot; is only ever said when an aircraft is cleared to take off.  For example, &quot;ready for departure&quot; tells the controller that the aircraft is prepared to take off immediately.  The crew should not say &quot;ready for takeoff&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can sometimes hear a pilot receiving a long instruction, start to read it back, pause, then ask for a repeat.  Very frustrating when you are sitting there waiting to get your request in.  You just know they thought they could remember it, but didn't.  Write it down if it's anything except a simple instruction or clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example of a complex one.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;SuperAir 123, cleared to Barcelona via vector departure, fly runway track, climb altitude 5000ft, after passing 2000ft turn right direct Hamm VOR, route as filed, squawk 1234, information Alpha current, startup approved &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The crew might write it down like this.  Each pilot develops their own preferred shorthand:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VD RWY TRK 5000 / 2000+ RT HMM / SQ1234 ALPHA / SU&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Very brief since they know what each part is and the order they come in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it contains instructions, the crew will then read it back.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cleared Barcelona via vector departure, runway track 5000ft, after passing 2000ft right direct Hamm, squawk 1234, Alpha on-board, startup approved. SuperAir 123.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Finally, a good reason to write stuff down is because sometimes (and we've all been there), you think you remember, then turn round to your co-pilot 2 minutes later and ask &quot;what was that altitude?&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a great &lt;a href=&quot;https://www.youtube.com/watch?v=D88EZJ2wJ7M&quot; rel=&quot;noreferrer&quot;&gt;example of someone who didn't have a pen&lt;/a&gt; and an approach to writing down clearances.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2017-06-18T18:21:35.560" LastActivityDate="2017-06-18T18:21:35.560" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="12887" PostTypeId="2" ParentId="12634" CreationDate="2015-02-24T23:38:09.690" Score="11" Body="&lt;p&gt;I'm a private pilot. I used X-Plane before getting my license, and a little bit while I was working on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say X-Plane is a good simulator. There are some things though that are just not at all realistic. Landings are WAY too easy on X-Plane. You just get the plane above the runway, cut the engines, and you'll land. You could be like 100 feet above the runway and it'd probably land okay by just cutting the engines. A real plane is not like this at all.  In fact, X-Plane is &lt;em&gt;so&lt;/em&gt; easy to land that it interferes with practicing different types of landings (short, soft, slips, etc.) You can't even really practice landings with it -- at least not with any fidelity to reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also say that in general the planes don't &quot;feel&quot; that real. Everything is too perfect. For example, in a real plane, if you jam the throttle forward too quickly, you can kill the engine or make it backfire. This may sound like a trivial detail, but people have died on takeoff because they never learned proper throttle technique. The fact that you can't simulate this in X-Plane is one small example of the &quot;over perfection&quot; of the simulation. There are countless others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that you can't pivot your head (or even simulate it with a joystick or something) is majorly annoying. You basically have little fixed views that you can switch to with a high-hat button on your yoke.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The X-Plane design team seems to have focused heavily on realism of airflow and weather, and not so much on realism of the world. When you're learning cross country flight, it would be wonderful to fly a trip in X-Plane and have familiar landmarks, but alas it doesn't work that way unless you're in a major metropolitan area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's a good simulator, but it's not super close to reality. It's great for learning (most) procedures, and it certainly gives you a rough idea of what piloting is like, but sometimes I found it more of a hindrance than a help when I was learning to fly.&lt;/p&gt;&#xA;" OwnerUserId="6840" LastEditorUserId="65" LastEditDate="2015-02-25T14:16:50.780" LastActivityDate="2015-02-25T14:16:50.780" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12888" PostTypeId="2" ParentId="12885" CreationDate="2015-02-25T01:14:03.573" Score="21" Body="&lt;p&gt;The lengthiest instruction is a clearance.  A common mnemonic for that is &lt;a href=&quot;http://en.wikipedia.org/wiki/CRAFT_(aviation)&quot;&gt;CRAFT&lt;/a&gt; for &lt;strong&gt;c&lt;/strong&gt;learance limit, &lt;strong&gt;r&lt;/strong&gt;oute of flight, initial &lt;strong&gt;a&lt;/strong&gt;ltitude, departure &lt;strong&gt;f&lt;/strong&gt;requency, and &lt;strong&gt;t&lt;/strong&gt;ransponder code.  If I'm not getting a clearance via &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot;&gt;ACARS&lt;/a&gt; I'd jot CRAFT (vertically) down on a the dispatch paperwork (or a kneeboard if I'm flying recreationaly) and write the relevant parts of the clearance next to the letters.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For many other instructions if not very short I'll use the FMS as a scratchpad for shorthand notation.  For example for an instruction like &quot;Taxi runway 27 via W, M, S, K hold short B&quot; I'd write &lt;code&gt;27 WMSK/B&lt;/code&gt;.  Similarly for an instruction like &quot;Cross SWEET at 7000&quot; I'd write &lt;code&gt;SWEET/7&lt;/code&gt; or &lt;code&gt;/7000&lt;/code&gt; (the latter of which I could then put in the FMS for VNAV guidance).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="65" LastEditDate="2015-02-25T14:27:31.750" LastActivityDate="2015-02-25T14:27:31.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12889" PostTypeId="1" CreationDate="2015-02-25T02:03:59.953" Score="9" ViewCount="663" Body="&lt;p&gt;Are there any correctives or countermeasures against the rare irony, that objects essential to a flight accident (eg recovered flight data recorder and cockpit voice recorders) are damaged or destroyed on a subsequent flight carrying them? The worst case is if this freight flight crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Context: As in many other Air Crash Investigation episodes, &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_Mayday_episodes#Season_14_.282014.29&quot;&gt;Season 14 Episode 4&lt;/a&gt; (&lt;a href=&quot;https://www.youtube.com/watch?v=e-YFmpi5KbU&quot;&gt;available on Youtube&lt;/a&gt;) concerns &lt;a href=&quot;http://en.wikipedia.org/wiki/Copa_Airlines_Flight_201&quot;&gt;Copa Airlines Flight 201&lt;/a&gt;. Due to a lack of facilities in Panama or Colombia, the recovered FDR and CVR and other parts (including the cockpit instruments) had to be transported to the NTSB's labs in Washington, DC, USA. I presume that for want of expediency, they were freighted by air? &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="22726" LastEditDate="2019-05-27T02:55:44.587" LastActivityDate="2019-05-27T02:55:44.587" Title="What if a flight, transporting a recorder from an aviation accident, crashes?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;&lt;flight-recorders&gt;" AnswerCount="1" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="12890" PostTypeId="1" CreationDate="2015-02-25T03:04:31.147" Score="4" ViewCount="284" Body="&lt;p&gt;I encountered &lt;a href=&quot;https://www.youtube.com/watch?v=e-YFmpi5KbU&amp;amp;google_comment_id=z130dllgwyfvyx33y225t5v5fmnvcnkfa&quot; rel=&quot;nofollow&quot;&gt;the original question here&lt;/a&gt;; I tried to improve the prose by editing it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Secondly, about all air disasters involving high-speed impact with terrain, how can investigators trust results from testing instrumentation that hit the ground? In &lt;a href=&quot;http://en.wikipedia.org/wiki/Copa_Airlines_Flight_201&quot; rel=&quot;nofollow&quot;&gt;Copa Air Flight 201&lt;/a&gt; they tested the captain's gyro and found it faulty. It probably was, but isn't there the possibility that the gyro was damaged as a result of the impact? I'd really like to hear from an investigator on how it is they determine that test results are so reliable that they can come to a definitive conclusion as to why the accident occurred.﻿&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[User '&lt;strong&gt;bonmec101&lt;/strong&gt;' writes,  week of 2015 Feb 3]&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;+[user] &lt;strong&gt;Marvin Kitfox&lt;/strong&gt; &quot;If you test an instrument from a crashed plane, and it works, you can be pretty dang sure it worked before the crash.&quot;    &lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;you haven't seen &quot;Hidden Danger&quot; then [which examines &lt;a href=&quot;http://en.wikipedia.org/wiki/USAir_Flight_427&quot; rel=&quot;nofollow&quot;&gt;USAir Flight 427&lt;/a&gt;). One of my most favorite episodes.﻿&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=e-YFmpi5KbU&amp;amp;google_comment_id=z130dllgwyfvyx33y225t5v5fmnvcnkfa&quot; rel=&quot;nofollow&quot;&gt;User 'diegus012' answers here, on 2015 Feb 21&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="128" LastActivityDate="2015-02-25T16:22:09.767" Title="How can investigators trust flight instrumentation from aviation accidents?" Tags="&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12891" PostTypeId="1" AcceptedAnswerId="12899" CreationDate="2015-02-25T03:07:16.567" Score="20" ViewCount="3236" Body="&lt;p&gt;User 'Calphool' &lt;a href=&quot;https://aviation.stackexchange.com/a/12887&quot;&gt;writes&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For example, in a real plane, if you jam the throttle forward too quickly, you can kill the engine or make it backfire. This may sound like a trivial detail, but people have died on takeoff because they never learned proper throttle technique.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Why and how? &lt;/li&gt;&#xA;&lt;li&gt;What accidents were caused by mishandling of the throttle levers? &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2020-03-07T05:23:48.077" Title="Why must the throttle be moved slowly?" Tags="&lt;accidents&gt;&lt;throttle&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12892" PostTypeId="1" AcceptedAnswerId="12893" CreationDate="2015-02-25T03:48:11.220" Score="3" ViewCount="1324" Body="&lt;p&gt;In the takeoff roll, I'm pretty sure planes produce some lift before rotation, but how much? Is it insignificant compared to post-rotation, or is it large compared to the post-rotation lift?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-02-25T04:19:59.440" LastActivityDate="2015-04-09T19:44:24.863" Title="How much lift do planes produce before rotation?" Tags="&lt;aerodynamics&gt;&lt;takeoff&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12893" PostTypeId="2" ParentId="12892" CreationDate="2015-02-25T05:50:33.117" Score="7" Body="&lt;p&gt;Check out this plot (taken &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift_coefficient&quot; rel=&quot;nofollow noreferrer&quot;&gt;from wikipedia&lt;/a&gt;), of the lift coefficient against angle of attack. During takeoff roll, lift will be increasing due to the speed increasing, however not enough (in general) for the plane to achieve takeoff without rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once rotation starts, the lift increases dramatically, for (a very rough) example, consider a plane on takeoff roll, then rotating to 15 degrees angle of attack. By looking at the lift/AoA plot, we can see that the lift coefficient increases from roughly 0.55 to 1.7, giving roughly 3 times as much lift as before rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/y45wh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4287" LastActivityDate="2015-02-25T05:50:33.117" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12894" PostTypeId="5" CreationDate="2015-02-25T07:41:51.517" Score="0" Body="" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-25T07:41:51.517" LastActivityDate="2015-02-25T07:41:51.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12895" PostTypeId="4" CreationDate="2015-02-25T07:41:51.517" Score="0" Body="Planespotting is a hobby where photographers try to take pictures of aircraft around airports and share them within a community." OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-25T07:41:51.517" LastActivityDate="2015-02-25T07:41:51.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12896" PostTypeId="2" ParentId="12889" CreationDate="2015-02-25T08:50:36.703" Score="12" Body="&lt;p&gt;If the &lt;strong&gt;Flight Data Recorder&lt;/strong&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_data_recorder&quot;&gt;FDR&lt;/a&gt;) and &lt;strong&gt;Cockpit Voice Recorder&lt;/strong&gt; (CVR) need to be transported by airfreight, to expedite extraction of the recorded data and analysis of the accident, the probability of the aircraft used to ferry the devices crashing is rather low, as aircraft accidents do not happen as frequently compared to the total of movements per day/week/month/year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, in the event of the aircraft used to ferry the devices crashing, the FDR and CVR are built to survive crashes and impact, so the probability of the first pair of FDR and CVR being still usable for data extraction after a second crash is quite high. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the FDR and CVR record not only data but also timestamps along with the data, the distinction between the FDR/CVR from the first crash and the FDR/CVR from the second crash is not a problem. Upon data extraction, the investigating party would recognize which flight parameters belong to which flight. Additionally, if the FDR and CVR on both flights were identical models, the serial number of each device would help identification.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-02-25T16:17:22.597" LastActivityDate="2015-02-25T16:17:22.597" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12898" PostTypeId="2" ParentId="1147" CreationDate="2015-02-25T11:38:45.960" Score="11" Body="&lt;p&gt;Could we record &lt;strong&gt;everything&lt;/strong&gt; to the cloud? No. For one thing, we just don't have the storage capability and communication bandwidth. Transmitting data from a plane travelling at mach 0.85 over the atlantic is no mean feat: we've managed it, but it isn't like a home fibre connection running at a steady 100Mbit/s or more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add in the fact that currently we aren't saturating the satellites right now... but if suddenly every plane was transmitting at full speed constantly, both the frequencies used, and the satellites themselves, would quickly be saturated. We would need a LOT of satellites and a much larger frequency band allocated to that transmission type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's storage: there are thousands of planes in the sky, recording several gigabytes of data per hour. Perhaps if we used a similar &quot;keep 24 hours of data&quot; strategy, this could be manageable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, we could, and probably should, transmit and record &lt;strong&gt;some&lt;/strong&gt; data, or at least &lt;strong&gt;more&lt;/strong&gt; data than we do now. At the very least, we should be able to transmit basic telemetry and control input positions, along with perhaps a little information regarding engine power settings etc. They wouldn't necessarily be up to the level of the Flight Data Recorder of Cockpit Voice Record information, but it would at least give us something to work with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since MH370, there's talk of ensuring we, at the very minimum, know the location of every aircraft in close to real time, so if nothing else we should be able to localise the search area faster in future.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2017-01-30T15:37:56.880" LastActivityDate="2017-01-30T15:37:56.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12899" PostTypeId="2" ParentId="12891" CreationDate="2015-02-25T11:39:45.810" Score="20" Body="&lt;p&gt;There are a few ways rough throttle handling on a propeller airplane can get you into trouble:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Gyroscopic yaw and torque: a rotating prop creates yaw 90 degrees to its spin which are offset by control inputs (mainly rudder), throttling up or down requires changes to these control inputs. Quick changes require bigger changes, slower changes give a pilot more time and allows smoother transitions. This isn't that big a consideration on lower-powered aircraft but it is on high-performance aircraft. In the first case that comes to mind an inexperienced P-51 pilot rammed full throttle in on a go-around and it flipped the aircraft on its back. At low airspeed it's possible there wasn't enough control authority to manage the forces even if he had been prepared for them&lt;/li&gt;&#xA;&lt;li&gt;Pitch changes: most aircraft will have a pitch change when the throttle is increased or decreased, again quick changes require coarser changes in controls while slower changes mean smoother and better controlled inputs. Again more applicable to higher performance aircraft&lt;/li&gt;&#xA;&lt;li&gt;Engine and carburetor: The engines in most light propeller-driven airplanes represent the pinnacle of 1950's technology. Fuel mixture, priming, and throttle control are all completely manual - there are no electronic systems to help smooth things out during throttle changes. Many airplane engine carburetors do not have an accelerator pump to shoot extra fuel to prevent the engine stalling during a quick throttle up. Given that an engine stall when airborne is a life-threatening emergency it's in your interest to make smooth, controlled changes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Although not usually a safety issue wear and tear is also a consideration. Smooth, gentle changes are better for the levers, plungers, and cables in the engine control system. Less wear and tear means better reliability and less costs. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-02-25T18:16:55.880" LastActivityDate="2015-02-25T18:16:55.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12900" PostTypeId="1" AcceptedAnswerId="12906" CreationDate="2015-02-25T12:03:34.467" Score="7" ViewCount="1166" Body="&lt;p&gt;I am trying to estimate the noise-related costs for a long-range platform aircraft (for example, the Boeing 787) at Heathrow Airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have &lt;a href=&quot;http://www.boeing.com/commercial/noise/2011HeathrowConditionsofUse.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;found the following table (PDF, page:24)&lt;/a&gt; outlining some costs for night/day landings, but &lt;strong&gt;can anyone tell me which 'chapter' a B787 would considered?&lt;/strong&gt; I have looked around extensively, but cannot find any clear explanation on this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wJfIH.png&quot; alt=&quot;Noise Charges&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7425" LastEditorUserId="65" LastEditDate="2015-02-25T15:26:18.577" LastActivityDate="2015-02-25T15:57:29.503" Title="How much are noise-related landing costs for a long-range aircraft at Heathrow?" Tags="&lt;landing&gt;&lt;cost&gt;&lt;noise&gt;&lt;aeroacoustics&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12901" PostTypeId="2" ParentId="12900" CreationDate="2015-02-25T12:40:28.143" Score="5" Body="&lt;p&gt;The B787 is a chapter 4 aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know whether that would be chapter 4 'High', 'Base' or 'Minus'. These qualifications seem to be specifically used at Heathrow. I'd expect the B787 to be in the Base or Minus category since its noise levels are well below the ICAO&#xA;Chapter 4 standard.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-02-25T12:40:28.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12902" PostTypeId="1" CreationDate="2015-02-25T12:48:04.577" Score="1" ViewCount="413" Body="&lt;p&gt;Trains, as far as I'm aware, just dump human waste on to their own tracks. There are often warnings like: &lt;code&gt;DO NOT USE the toilet while the train is stopped at the station&lt;/code&gt; voiced through the PAs or signed up on the walls. &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2526535/Train-firms-banned-allowing-utterly-disgusting-toilets-flush-sewage-tracks.html#ixzz3SlArr0qL&quot; rel=&quot;nofollow&quot;&gt;The Daily Mail&lt;/a&gt;, in 2014 had an article mentioning: &lt;code&gt;Train companies are to be ordered to adapt their trains to stop dumping sewage on the tracks.&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I always kind of assumed that commercial airliners did the same, but I've never heard any warnings about using the restrooms aside from when the seat-belt sign is on.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How do commercial airliners take care of human waste?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5642" LastEditorUserId="572" LastEditDate="2015-02-25T12:55:22.827" LastActivityDate="2015-02-25T13:02:18.577" Title="How is human waste taken care of on commerical aircraft?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-02-25T14:00:03.830" ContentLicense="CC BY-SA 3.0" />
  <row Id="12903" PostTypeId="2" ParentId="12902" CreationDate="2015-02-25T12:53:21.387" Score="3" Body="&lt;p&gt;Human waste from the lavatories is collected on-board and later &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_lavatory#Lavatory_agents&quot; rel=&quot;nofollow noreferrer&quot;&gt;disposed of at the airport after landing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QF3PX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Aircraft_lavatory_service.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiMedia Commons&lt;/a&gt; - Author: Mnts)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check out this related question here on Aviation.SE:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/2361/572&quot;&gt;Where does my pee go when I flush at 35,000 ft?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-25T13:02:18.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12904" PostTypeId="2" ParentId="12859" CreationDate="2015-02-25T13:06:50.837" Score="4" Body="&lt;p&gt;The  &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Extra_EA-300&quot; rel=&quot;nofollow&quot;&gt;G-limit for the Extra 300&lt;/a&gt; (the parent airplane to the 330):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Extra 300 is stressed for ±10 G with one person on board and ±8 G with two&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is certainly possible from an &lt;em&gt;airplane&lt;/em&gt; perspective that you pulled that many Gs - in an aerobatic airplane, it's not unheard of to pull 1G less than the aircraft limit (usually there is a large margin of safety built into that number before a &lt;em&gt;catastrophic structural failure&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now did &lt;em&gt;you&lt;/em&gt; pull 7Gs? As others have noted, 7Gs for 10-20 seconds seems very unlikely. But it is not out of the question your peak instantaneous G load was 7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a human factor standpoint, G-suits typically don't increase the max G-load, but rather &lt;a href=&quot;http://en.m.wikipedia.org/wiki/G-suit&quot; rel=&quot;nofollow&quot;&gt;increase the sustained G-load&lt;/a&gt; and the time period it can be held for. G-suits do very little to actually decrease blood flow (pooling in the legs) - they primarily serve as a reminder to the pilot to perform an AGSM. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A g-suit does not so much increase the g-threshold, but makes it possible to sustain high g longer without excessive physical fatigue. The resting g-tolerance of a typical person is anywhere from 3-5 g depending on the person. A g-suit will typically add 1 g of tolerance to that limit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now there are a vast array of factors affecting this resting G-tolerance. I flew  a military high-performance trainer, and my resting G-tolerance was around 3, or the lower end of the spectrum. One of the other pilots I knew had a resting G-tolerance of about 7.5. The primary difference is blood pressure. I am 5'10&quot; and only 145 pounds, with a resting blood pressure of about 90/60-100/70. He was 6'0&quot; and about 215 pounds, with a much higher blood pressure. Tall, skinny, nonsmoking runners have actually the worst resting G-tolerance while short, stocky, sedentary or heavily muscled smokers have much higher tolerance. Other factors, such as how hydrated and rested you are and how much stress you are feeling, can vary vastly your daily G-tolerance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of those numbers I just listed do not take into account the pilot performing an AGSM (Anti-G Straining Maneuver). This can add several Gs to the pilot's tolerance, and is one of the biggest things taught in physiological training for high-G maneuvers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So &lt;strong&gt;TL; DR&lt;/strong&gt;: could you have pulled 7Gs without prior exposure? It is possible, depending on varying personal factors and body type, but it is not &lt;em&gt;likely&lt;/em&gt;. However, with a little training, 7Gs is perfectly attainable. &lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="774" LastEditDate="2015-03-25T19:44:32.463" LastActivityDate="2015-03-25T19:44:32.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12905" PostTypeId="2" ParentId="2581" CreationDate="2015-02-25T14:26:31.253" Score="1" Body="&lt;p&gt;Your best bet would be &lt;a href=&quot;http://www.simspot.co.uk/simulator-experiences.htm&quot; rel=&quot;nofollow&quot;&gt;SimSpot&lt;/a&gt;. This way you can get a real look and feel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been past this spot time after time as is in the Cineworld but never ventured in. It's now on my checklist of things to do 2015 :)&lt;/p&gt;&#xA;" OwnerUserId="3355" LastEditorUserId="65" LastEditDate="2015-02-25T14:56:41.127" LastActivityDate="2015-02-25T14:56:41.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12906" PostTypeId="2" ParentId="12900" CreationDate="2015-02-25T15:57:29.503" Score="6" Body="&lt;p&gt;As DeltaLima states, the 787 is a Chapter 4 aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Directly under the table in your question is another table listing the requirements for each category.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyvLZ.png&quot; alt=&quot;Qualification criteria for noise categories&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the categories are based on the certified Chapter, and the margin to Chapter 3 standards. Based on these values, the 787 would be categorized as &lt;strong&gt;Chapter 4 Low&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can look up aircraft in the NoisedB &lt;a href=&quot;http://noisedb.stac.aviation-civile.gouv.fr/find.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;. Each aircraft is tested for its noise margin. I looked at ID:BOEING_14816, which is a 787-8 powered by a GEnx-1B. It has a noise margin of 30.9, which is compared to the Chapter 4 standard. From looking up a Chapter 3 aircraft like a 747-400, it can be seen that the cumulative reduction between Chapter 3 and 4 is 7.3 EPNdB. I did not see any aircraft that would be above the Chapter 4 Low levels, and most are in the &quot;30 or more&quot; category.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-25T15:57:29.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12907" PostTypeId="1" AcceptedAnswerId="12926" CreationDate="2015-02-25T16:11:24.047" Score="7" ViewCount="3598" Body="&lt;p&gt;Driving on the &lt;a href=&quot;http://en.wikipedia.org/wiki/M40_motorway&quot; rel=&quot;noreferrer&quot;&gt;M40&lt;/a&gt; recently just south of Banbury, England, I saw a distinctive smallish plane I'm trying to identify&amp;nbsp;&amp;mdash; probably military from the dull grey/green color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looked a lot like the &lt;a href=&quot;http://aircraftrecognition.co.uk/islander.html&quot; rel=&quot;noreferrer&quot;&gt;Islander&lt;/a&gt;, but:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It had a tailplane and twin fins&lt;/li&gt;&#xA;&lt;li&gt;The tail boom was narrower in proportion to the body&lt;s&gt;, and more distinct from the body than the Islander's is&lt;/s&gt; &lt;em&gt;(I think I'm misremembering or mis-saw that part&amp;nbsp;&amp;mdash; I &lt;strong&gt;was&lt;/strong&gt; driving on the motorway, after all)&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;The body may well have been a bit bulkier (or that may have been an illusion caused by the narrowness of the tail boom)&lt;/li&gt;&#xA;&lt;li&gt;The wings had a normal-looking span for the size of the aircraft but were shorter front-to-back than seemed normal (to my very-much-not-expert eye)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Like the Islander it was a twin prop with a fairly pointy nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have any idea what it was?&lt;/p&gt;&#xA;" OwnerUserId="3531" LastEditorUserId="3531" LastEditDate="2015-02-27T08:20:22.127" LastActivityDate="2015-02-27T22:05:29.510" Title="What UK aircraft looks like an Islander but with twin fins?" Tags="&lt;military&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="12908" PostTypeId="2" ParentId="12890" CreationDate="2015-02-25T16:22:09.767" Score="5" Body="&lt;p&gt;Investigators have experience in inspecting damaged equipment. Over the years they develop an understanding of what kind of damage comes from crashes. Based on this experience they can determine whether the damage is consistent with a crash or just typical operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As raptortech97 commented, the gyro from Copa 201 had a wire nearly severed. This is exactly the kind of normal damage that could happen to a gyro in operation, but not the kind of damage that would happen inside a gyro during a crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are many instances where investigators are unable to determine whether equipment was damaged before the crash. Items may be too badly damaged to determine this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The comment about USAir 427 is also relevant. See also British Airways 38. Some failure modes leave no evidence behind, and thus are difficult to diagnose afterwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The investigation will take all of these factors into account along with all other evidence they have. They will not claim a definitive answer based on uncertain test results alone. In the case of Copa 201, the data from the FDR matched the behavior of a gyro with a loose connection, which matched the circumstances of the crash. In the case of the 737 PCU (USAir 427) and RR FOHE (British Airways 38), once the failure mode was tracked down, it was tested in the lab to confirm that such a failure was possible and could cause the expected effects, and to determine the best method to prevent it in the future.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-02-25T16:22:09.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12909" PostTypeId="1" AcceptedAnswerId="12913" CreationDate="2015-02-25T16:56:24.580" Score="10" ViewCount="327" Body="&lt;p&gt;There have been several crashes due to ice on wings destroying lift. One of the issues with this is that you can't detect that you don't have sufficient lift until you're already in the air, way too late to abort.&#xA;Some aircraft have &lt;a href=&quot;https://aviation.stackexchange.com/q/1850/3170&quot;&gt;weighing scales in the landing gear&lt;/a&gt;. Could these be used to verify the expected lift, and abort if an anomaly was detected before $V_1$?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-02-26T20:57:15.183" Title="Could landing gear weighing scales be used to detect lack of lift?" Tags="&lt;aerodynamics&gt;&lt;landing-gear&gt;&lt;weight-and-balance&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12911" PostTypeId="2" ParentId="12891" CreationDate="2015-02-25T19:57:50.220" Score="12" Body="&lt;p&gt;This actually happened to me about two months ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a very cold night, I went to do my night-currency (3 takeoffs and landings) in a Cessna SkyCatcher (C-162). The plane was hard to start due to the freezing temperatures, but eventually got it going. I did the normal run-up checks, took off, and did one loop around the pattern, coming back for a normal landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I made a full stop on the runway, reset the flaps, and pushed the throttle forward.&#xA;The engine instantly died. I told the tower I was stuck on the runway, and he held up some other traffic that was looking to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multiple attempts to get the engine restarted failed. Eventually, the FBO sent a tug out to pull me off the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later I talked to the Chief Pilot who was aware of the problem, and most frighteningly of all, said that it definitely could happen in the air. If I had decided I needed a go-around on short-final, and pushed the throttle too quickly, it may have killed the engine when I needed it most.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not think that I &quot;jammed&quot; the throttle forward, but I may have pushed a little aggressively. I will always be very gentle on my throttle from now on. But what concerns me is those times when you need power quickly (such as a go-around near the ground), you just may not have time to do a slow-and-easy acceleration.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="65" LastEditDate="2015-02-25T21:59:43.567" LastActivityDate="2015-02-25T21:59:43.567" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12912" PostTypeId="1" AcceptedAnswerId="12918" CreationDate="2015-02-26T01:59:04.127" Score="12" ViewCount="2762" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/changes/&quot;&gt;Flight Service Program Changes&lt;/a&gt; announcement from the FAA includes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On October 1, 2015, the FAA will consolidate Flight Watch services into routine flight services inflight frequencies to eliminate unnecessary duplication of service and provide greater convenience for pilots. These services provide inflight weather information to pilots. After that date, these services will be available on the same frequencies that pilots use to open and close flight plans and to receive updates on NOTAMs or Temporary Flight Restrictions (TFRs). Dedicated Flight Watch frequencies will be decommissioned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What are the &amp;ldquo;dedicated Flight Watch frequencies,&amp;rdquo; plural? The mnemonic drilled into my head was Flight Watch on 122.0, with the zero shaped like the face of a wrist watch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only frequencies I, a student pilot, have ever used for opening and closing flight plans has been &lt;a href=&quot;https://en.wikipedia.org/wiki/Remote_communications_outlet&quot;&gt;RCO&lt;/a&gt;. The wording above is not specific, so does that mean instead of one dedicated frequency, you have to know the local RCO frequency to call Flight Watch?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="572" LastEditDate="2015-02-26T08:58:50.090" LastActivityDate="2015-02-26T14:13:43.460" Title="Will the frequency 122.000 MHz no longer be used for Flight Watch after October 1st 2015?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12913" PostTypeId="2" ParentId="12909" CreationDate="2015-02-26T12:46:05.553" Score="7" Body="&lt;p&gt;Technically one could develop a system that compares the decrease in weight-on-wheels during the take-off run to a theoretical lift model in order to determine whether the wings are performing as expected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see a number of reasons why this will not be successful a product:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Limited benefits&lt;/strong&gt;:&#xA;The benefit of such a system is minimal. There are very few crashes due to contaminated wings or wrong flap/slat configurations. Let's assume there are one hundred thousand airline flights per day and one lift related take-off crash every 4 years. That is one in 150 million.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Available alternatives&lt;/strong&gt;. &#xA;For both causes there are viable alternatives to detect them well before V&lt;sub&gt;1&lt;/sub&gt;. Visual inspection of the wing usually detects contamination and many aircraft automatically check for the take-off configuration to be set whenever the thrust increases beyond a pre-defined trigger level.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Increase in number of rejected take-offs&lt;/strong&gt;: No system is perfect. It will detect some contaminated wing situations and save the day, but it will also cry wolf in cases where there is nothing to abort a take-off for. If the system has a false alert rate of one in ten thousand take-offs (which would be very good and expensive to design and certify) it would cause 15000 aborted take-offs (assuming the same numbers as above) for every crash it prevents (assuming a missed alert rate of 0).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Since lift increases with the square of air speed, it is difficult to detect lack of lift early on during the take-off run. At low speed there is relatively little lift to be expected and it will be in the noise of the measurement. Also the accuracy of the airspeed indicator is relatively low at low speeds, so the theoretical lift model will not give accurate results either. As a consequence the system will only be able to detect lack of lift at high speeds. At those higher speeds, the influence of bumps in the runway start to affect the measurements as well. It is easy to see that detecting lack of lift is no so straight forward. False alerts will be raised and they will be at raised at high speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;High speed rejected take-offs &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_11/takeoff_story.html&quot; rel=&quot;nofollow&quot;&gt;are risky.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boeing studies indicate that approximately 75 percent of RTOs are&#xA;  initiated at speeds less than 80 kt and rarely result in an accident.&#xA;  About 2 percent occur at speeds in excess of 120 kt. The overruns and&#xA;  incidents that occur invariably stem from these high-speed events.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So effectively such a system will likely &lt;strong&gt;increase the number of accidents&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1696" LastEditDate="2015-02-26T18:09:27.197" LastActivityDate="2015-02-26T18:09:27.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12914" PostTypeId="1" AcceptedAnswerId="12916" CreationDate="2015-02-26T13:15:46.960" Score="12" ViewCount="4260" Body="&lt;p&gt;In a situation where the pilot realizes that weight of the aircraft is too high, can they dump luggage / cargo mid air, similar to dumping fuel?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="572" LastEditDate="2015-02-27T07:08:49.153" LastActivityDate="2019-04-27T04:27:58.720" Title="Can commercial aircraft dump luggage or cargo mid-air?" Tags="&lt;cargo&gt;&lt;fuel-dumping&gt;" AnswerCount="3" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="12915" PostTypeId="1" CreationDate="2015-02-26T13:21:49.087" Score="22" ViewCount="9153" Body="&lt;p&gt;Boeing aircraft generally have a pointy nose, which seems to me to imply better aerodynamic qualities, less drag etc. Airbus aircraft on the other hand have rather bulbous noses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this difference to give Boeing and Airbus aircraft a consistent, distinctive visual appearance, or is there any specific aerodynamic reason for the different designs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/icOcR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;This image is only an example and my question is not about any specific model.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="14897" LastEditDate="2018-05-16T19:41:18.470" LastActivityDate="2020-05-04T08:06:39.270" Title="Why do Boeing and Airbus have distinctively different nose designs?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;airbus&gt;&lt;boeing&gt;&lt;nose&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12916" PostTypeId="2" ParentId="12914" CreationDate="2015-02-26T13:28:56.213" Score="25" Body="&lt;p&gt;No they can't. The cargo doors are secured and will not open mid-flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cargo holds are usually pressurized so opening the door anyway would cause depressurization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also if the weight was too high the pilot should never have lifted off in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then after you theoretically throw the stuff off board think about what happens after to the stuff. It will drop down &lt;em&gt;hard&lt;/em&gt; probably on someone's roof.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only some military cargo planes with a back hatch are designed to jettison cargo.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-02-26T19:16:42.517" LastActivityDate="2015-02-26T19:16:42.517" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="12917" PostTypeId="1" AcceptedAnswerId="12919" CreationDate="2015-02-26T13:54:19.180" Score="8" ViewCount="3425" Body="&lt;p&gt;I saw this &lt;a href=&quot;https://www.youtube.com/watch?v=iRPHqaZO6HU&quot; rel=&quot;nofollow&quot;&gt;YouTube video&lt;/a&gt; about a Gulfstream jet that came into landing on Princess Juliana International airport and the landing does not seem to be by the book at all. It seems like the landing gear is only a few centimeters from hitting the fence and a meter from hitting the people on the beach. It looks like to me that he is way below the glideslope, but since I'm not that familiar with Princess Juliana I really can't confirm anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any more information available about this incident? Was it actually a normal landing, or was it caused by wind shear or pilot error? How often does this occur?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found this comment in the comment section from someone who claim to be a long time pilot:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Juliana is Class D so 91.129 and 703 applies:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;FAR 91.129 (E) &quot;An airplane approaching to land on a runway served by&#xA;  a &lt;strong&gt;visual approach&lt;/strong&gt; slope indicator shall maintain an altitude at&#xA;  or above the glide slope until a lower altitude is necessary for a&#xA;  safe landing.&quot;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;See also FAR 91.703 (a)(1) &quot;Each person operating a civil aircraft of U.S. registry outside of the United States shall: when over the&#xA;  high seas, comply with annex 2 (Rules of the Air) to the Convention&#xA;  on International Civil Aviation and with 91.117(c), 91.127,&#xA;  &lt;strong&gt;91.129&lt;/strong&gt;, and 91.131;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;They were way below the visual glide slope indicators i.e PAPIs (for Juliana), and (from flying this approach myself) it's not necessary for a safe landing. Besides ...it's just not very good practice.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Sincerely, Long time pilot. (:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have to say that by my logic thinking: I agree with this guy. I am not a pilot myself, but here is why I agree with him:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low approach method:&lt;/strong&gt;&#xA;If the plane hits the fence: It could cause the gear to break of (And maybe hit someone) and when the plane touches down on the runway with broken landing gear at flying speed: It could cause a rapture in the fuel tanks, igniting it. And you are essentially a tumbling fireball down the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;High approach method:&lt;/strong&gt;&#xA;If you fly higher to avoid the fence: The chances of hitting it and cause a tumbling fireball are greatly lowered. However: You may overrun the runway. But this would be preferred (In my book atleast). Since the plane has touched down on the runway and slowed down: You decrease the chances of fuel ignition when you overrun. And if the fuel ignites at the end: You will most likely end up with the fish. And the fire may not be put out completely, but greatly suppressed. And since the speed also is lowered: The chances of survival is greatly improved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is just my personal look on this. And some may or may not agree with me. But since the YouTube comment is there: I though there might be something to this.&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="693" LastEditDate="2015-02-27T08:50:00.827" LastActivityDate="2020-10-29T00:23:37.847" Title="Was this Gulfstream way below the glideslope?" Tags="&lt;safety&gt;&lt;landing&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12918" PostTypeId="2" ParentId="12912" CreationDate="2015-02-26T14:00:31.963" Score="4" Body="&lt;p&gt;Below 18,000 feet MSL, En Route Flight Advisory Service (EFAS) (a.k.a. Flight Watch) is provided on 122.0 MHz. Above this altitude, it is provided on discrete frequencies, with each one serving a specific ARTCC area (&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0701.html#IGH3a2JACK&quot; rel=&quot;nofollow noreferrer&quot;&gt;see AIM 7-1-5&lt;/a&gt;, &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/fac/1403.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA JO 7210.3Y Section 3&lt;/a&gt;).  These discrete frequencies are listed in the margin of IFR Enroute High Altitude charts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VP6qR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your original question, the FAA plans to consolidate EFAS onto existing Flight Service Station (FSS) frequencies on October 1, 2015. Because Lockheed Martin (the FSS contractor) has consolidated flight service stations, the EFAS weather briefers are now co-located with Flight Service personnel (they physically sit next to each other in the same room), making it possible to obtain both services on the same frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, the FAA will phase out legacy Remote Airport Advisory Services and more significantly, require the ICAO format for all flight plans (international AND DOMESTIC), see &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/changes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Service Program change announcement&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-02-26T14:13:43.460" LastActivityDate="2015-02-26T14:13:43.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12919" PostTypeId="2" ParentId="12917" CreationDate="2015-02-26T14:31:31.097" Score="19" Body="&lt;p&gt;There's no incident here. St Martin has a very short runway which spans a small stretch of land between 2 beaches, it's an airport where jets need to be on the numbers. It's famous among plane watchers and there are hundreds of videos of aircraft coming in low enough it seems as if you could reach up and touch the landing gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if there was a glideslope this aircraft was certainly below it, however it's not an instrument landing so glideslope had nothing to do with it. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="595" LastEditDate="2016-06-04T08:44:12.297" LastActivityDate="2016-06-04T08:44:12.297" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12921" PostTypeId="1" AcceptedAnswerId="12922" CreationDate="2015-02-26T16:35:18.533" Score="1" ViewCount="5274" Body="&lt;p&gt;In the A320-200's '&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A320_May2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIRCRAFT CHARACTERISTICS AIRPORT AND MAINTENANCE PLANNING&lt;/a&gt;' document. It presents the A320's PL/R capabilities as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aERtD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, I would like to know: What are the 3 different MTOW's listed? Is it for different seating layouts? eg 'high density' vs 'business + economy' or what? Note that 73.5(78) tonnes is the MTOW listed on Airbus's website, seen &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a320family/a320/specifications/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, but they don't clearly indicate what the figure in brackets indicates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, does the payload axis include passengers as well as cargo? If so, if the maximum amount of passengers is listed as 180, how much additional cargo can the aircraft carry, both in the cargo hold and overhead luggage trays? i.e. what model does the airlines/airframers use to estimate the weight of 180 passengers?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="19" LastEditDate="2016-07-08T16:46:01.300" LastActivityDate="2016-07-08T16:46:01.300" Title="What is the explanation for the different lines in the payload/range diagram for the Airbus A320?" Tags="&lt;airbus&gt;&lt;weight-and-balance&gt;&lt;airbus-a320&gt;&lt;payload&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12922" PostTypeId="2" ParentId="12921" CreationDate="2015-02-26T17:17:41.093" Score="5" Body="&lt;p&gt;There are two different Maximum Take Off Masses (MTOM) listed in the graph: 73.5 T and 78 T. This is only a small selection. The Airbus A320 has many variations due to modifications to fuel tanks, fuselage, engines, wings and landing gear. The following MTOMs have &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/EASA-TCDS-A.064_AIRBUS_A318,_A319,_A320,_A321_Single_Aisle-12-12092013.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;been certified (EASA PDF)&lt;/a&gt;: 66 T, 67 T, 68 T, 70 T, 71.5 T, 73.5 T, 75.5 T, 77 T and 78 T.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the variation in MTOM, there are variations in the number of fuel tanks installed. The A320-100 series have either 2 or 3 tanks, while the A320-200 series can have up to 5 tanks. More fuel tanks allow an increase in range at the cost of payload. Even on short flights additional tanks will decrease the maximum payloads due to their structural weight. The brown line in the chart represents an A320 with one Additional Centre Tank (ACT) installed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Payload includes passengers as well as cargo. Assuming an average adult weight of &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/Weight%20Survey%20R20090095%20Final.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;88 kg (EASA PDF)&lt;/a&gt; including carry-on luggage, 180 passengers weigh 15840 kg. Depending on the variant of A320 you take, that leaves a couple of tonne margin for other payload such as check-in luggage or fuel to increase the range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more on estimating aircraft loading, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1008/what-is-the-weight-budget-of-a-fully-loaded-a380&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-02-26T17:20:30.347" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12923" PostTypeId="2" ParentId="12917" CreationDate="2015-02-26T18:38:16.997" Score="9" Body="&lt;p&gt;Some of those Caribbean airports are really nuts. They squeeze them onto tiny little islands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 3-degree glide slope will be 10 feet high at 200 feet from the numbers, or just over the fence.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-02-26T21:33:03.383" LastActivityDate="2015-02-26T21:33:03.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12924" PostTypeId="2" ParentId="12909" CreationDate="2015-02-26T18:43:09.223" Score="1" Body="&lt;p&gt;Icing primarily occurs in the air. Icing does not normally occur on the ground, except during conditions of freezing rain, which obviously the crew will be aware of because they must positively acknowledge weather conditions before getting a taxi clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft will normally never take off if there is anything on the wings. The wings have to be absolutely clean before a pilot sets in motion a flight. Operating an aircraft with anything non-approved on the wing is a complete violation of FAA regulations and highly dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently in some instances pilots have taken off even though conditions of freezing rain have loaded down a wing with ice--sometimes with fatal results. Obviously such actions are reckless in the extreme and indicate the crew has not only not done a walkaround or checklist, but not even bothered to look at the wing. As a pilot, I would consider doing something like this unthinkable, but apparently there are some pilots who have done this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although your idea of using wheel strut scales to avoid this is interesting and innovative, it may be difficult to put it into practice because the weight of the ice will be relatively small compared to the overall weight of the aircraft. Also, if the pilots are so reckless as to not visually check their wings during a freezing rain storm, doing spreadsheet-like calculations to trying to detect ice by weight are certainly not going to be on their agenda.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-02-26T20:57:15.183" LastActivityDate="2015-02-26T20:57:15.183" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12925" PostTypeId="1" AcceptedAnswerId="12943" CreationDate="2015-02-26T19:56:19.313" Score="9" ViewCount="575" Body="&lt;p&gt;FAA defines a flying club in &lt;a href=&quot;https://www.faa.gov/airports/resources/publications/orders/compliance_5190_6/media/5190_6b_chap10.pdf&quot;&gt;5190.6b.ch10.6&lt;/a&gt; and ends by saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A flying club that violates the requirements for a flying club – or that permits&#xA;  one or more members to do so – may be required to terminate all operations as a flying club at all airports controlled by the airport sponsor. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So hypothetically if this were to occur, then you'd have an LLC that owns a plane that is &lt;em&gt;not&lt;/em&gt; a flying club. Does this mean that they wouldn't be able to fly their plane or carry on like normal? Aside from being able to label themselves as a &quot;Flying Club&quot;, what impact would this have?&lt;/p&gt;&#xA;" OwnerUserId="3495" LastActivityDate="2015-02-27T14:23:18.713" Title="What benefit does a group get from being an FAA recognized flying club?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12926" PostTypeId="2" ParentId="12907" CreationDate="2015-02-26T20:40:29.050" Score="12" Body="&lt;p&gt;It sounds an awful lot like a &lt;a href=&quot;http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/467765/c-145a.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-145&lt;/a&gt;, or maybe the 'civilian' version (it's primarily used by militaries), the  &lt;a href=&quot;https://en.wikipedia.org/wiki/PZL_M28_Skytruck&quot; rel=&quot;nofollow noreferrer&quot;&gt;PZL Skytruck&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UBetq.jpg&quot; alt=&quot;C-145&quot;&gt;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.919sow.afrc.af.mil/photos/mediagallery.asp?galleryID=10788&amp;amp;page=2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's used by the U.S. Air Force, so seeing it in Britain would not be surprising - all 3 of the U.S. Air Force's RAF joint use bases are within 100 air miles.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's twin-engine, with a tailplane and twin fins&lt;/li&gt;&#xA;&lt;li&gt;Its tail boom does narrow somewhat and distinguish itself, as seen &lt;a href=&quot;http://th06.deviantart.net/fs70/200H/f/2013/008/b/a/dat_skytruck_ass_by_indeepschit-d5qvbna.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;It does have somewhat of a chunky body&lt;/li&gt;&#xA;&lt;li&gt;The wings are fairly &lt;a href=&quot;http://www.americanspecialops.com/images/aircraft/skytruck.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;thin&lt;/a&gt; (front-to-back)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="774" LastEditorUserId="1696" LastEditDate="2015-02-27T22:05:29.510" LastActivityDate="2015-02-27T22:05:29.510" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12928" PostTypeId="1" AcceptedAnswerId="12929" CreationDate="2015-02-26T22:00:35.003" Score="11" ViewCount="3195" Body="&lt;p&gt;Recently, a small plane operating from a nearby airport suffered an engine failure on takeoff and crashed.  One of the hazmat responders dealing with the resulting fuel spill mentioned &quot;a strong smell of Jet A&quot;, leading to speculation that the airplane had its tanks filled with the wrong fuel.  Would he have been able to distinguish Jet A from 100LL by smell?&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2020-09-05T15:54:45.530" Title="Do Jet-A and 100LL smell different?" Tags="&lt;fuel&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12929" PostTypeId="2" ParentId="12928" CreationDate="2015-02-26T22:07:28.973" Score="17" Body="&lt;p&gt;If you know what you're looking (sniffing) for, yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avgas 100LL smells like gasoline (a little different than what you pump into your car, but similar).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet-A smells like kerosene (not quite &quot;like diesel&quot;, but definitely &lt;em&gt;not&lt;/em&gt; like gasoline).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are familiar with how both smell you can tell them apart by odor, and a significant contamination of Avgas with Jet-A could be detected by smell. (Other tests, like an evaporation test, are more reliable for lower levels of contamination however).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-26T22:07:28.973" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12930" PostTypeId="1" AcceptedAnswerId="12940" CreationDate="2015-02-26T22:47:58.063" Score="8" ViewCount="8771" Body="&lt;p&gt;In a scene of the movie &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Kingsman:_The_Secret_Service&quot;&gt;Kingsman: The Secret Service&lt;/a&gt;&lt;/em&gt; the young aspiring agents have to skydive from an airplane. I didn't recognise it: which airplane is it (assuming it actually exists)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could only find a picture &lt;a href=&quot;http://www.normankent.com/img/s10/v98/p459364338-3.jpg&quot;&gt;from inside&lt;/a&gt; and one &lt;a href=&quot;http://www.normankent.com/img/s6/v149/p790102179-3.jpg&quot;&gt;from below&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="705" LastEditorUserId="572" LastEditDate="2015-02-27T09:30:55.993" LastActivityDate="2016-03-13T00:02:53.530" Title="What type is this aircraft, appearing in the movie &quot;Kingsman&quot;?" Tags="&lt;aircraft-identification&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12931" PostTypeId="1" AcceptedAnswerId="12938" CreationDate="2015-02-26T23:18:53.300" Score="20" ViewCount="30203" Body="&lt;p&gt;Is there an international regulation for this matter or does it differ from one country to another? &lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="22726" LastEditDate="2018-06-05T17:46:26.743" LastActivityDate="2018-06-05T17:46:26.743" Title="What is the minimum distance allowed between two parallel runways?" Tags="&lt;runways&gt;&lt;regulations&gt;&lt;parallel-runways&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12932" PostTypeId="1" AcceptedAnswerId="12941" CreationDate="2015-02-26T23:19:21.200" Score="9" ViewCount="3494" Body="&lt;p&gt;What will be the reliability of the VOR indication inside the cockpit if one of the two outside antenna is broken ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can we trust it to make a VOR approach?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What will be the consequences assuming that we are in a general aviation aircraft like cessna 150 / 172 / 182 .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of antenna:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CttVB.jpg&quot; alt=&quot;Picture of antenna&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.simmer.fr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.simmer.fr/&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="7411" LastEditorUserId="22726" LastEditDate="2019-01-25T04:00:46.293" LastActivityDate="2019-01-25T04:00:46.293" Title="Can VOR indication be reliable if one of its antennas breaks?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;&lt;radio&gt;&lt;vor&gt;&lt;reliability&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12933" PostTypeId="2" ParentId="12932" CreationDate="2015-02-26T23:32:26.470" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR's direction&lt;/a&gt; doesn't come from the aircraft seeing where it comes from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOR works by a pulsing omni-directional beacon and a sweeping narrow beacon. The pulse happens each time the sweep is north. Then the heading from the compass is used to see where the beacon is relative to the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KuT5S.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:VOR_principle.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; - Author: Orion 8)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this mean that you can use it for navigation with a missing antenna?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Not unless the system was designed to compensate for a missing antenna.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-03-01T18:08:59.173" LastActivityDate="2015-03-01T18:08:59.173" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12934" PostTypeId="2" ParentId="12931" CreationDate="2015-02-27T00:01:31.660" Score="3" Body="&lt;p&gt;The distance between the runways is not the issue. Some of them are just a hundred feet apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue is that the closer the runways are, the more separation the planes using those runways must have, and the higher the IFR minima.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, below is a picture of Oakland International. The two smaller GA runways (28L and 28R) at the top are close together, but when the field is IFR, only one of them can be used for IFR operations. The runway at the bottom (29) is a commercial runway, but it is far enough from 28L that Oakland can have simultaneous IFR operations on 28L and 29.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mvLBh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Parallel_Runway_Operation&quot; rel=&quot;nofollow noreferrer&quot;&gt;This page&lt;/a&gt; gives you a pretty good idea of what to expect.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-02-27T00:01:31.660" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12935" PostTypeId="2" ParentId="3474" CreationDate="2015-02-27T00:36:02.180" Score="1" Body="&lt;p&gt;Power Sockets are getting pretty common these days. Most of the Widebodies (specially 777 and 380's have power outlets for 2 out of 3 Seats in each row). The Power Ratings also are 110V 60Hz commonly.&lt;/p&gt;&#xA;" OwnerUserId="7444" LastEditorUserId="7444" LastEditDate="2015-04-01T23:40:50.020" LastActivityDate="2015-04-01T23:40:50.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12937" PostTypeId="2" ParentId="12932" CreationDate="2015-02-27T00:58:44.357" Score="-4" Body="&lt;p&gt;Short answer: no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, if a piece of equipment has an operability issue, it should not be used for navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, if you test it and the test indicates it is functioning reasonably, it may be ok to use it on SHORT TERM BASIS. So, for example, if I were taking off from Manchester I would fly up to the Cordcord VORTAC and see if I were getting reliable readings. If so, I would probably feel ok using it on a VFR approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, the antenna should be fixed before using the instrument long term. To use the receiver with a damaged antenna once or twice is excusable, but not for an extended time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: By &quot;reliable&quot; readings I mean you are receiving a signal at different attitudes, or at least in the attitude you need for navigational purposes. The effect of a broken antenna will be to reduce your gain or possibly introduce a blind spot into your reception area. Note that these effects are ALWAYS present anyway. For example, in mountainous terrrain or if the VOR is straight ahead you could have blind spots in the VOR even with a perfect antenna. So, a broken antenna basically just makes standard reception problems you already have, worse.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-02-27T18:32:45.403" LastActivityDate="2015-02-27T18:32:45.403" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12938" PostTypeId="2" ParentId="12931" CreationDate="2015-02-27T01:03:04.383" Score="16" Body="&lt;p&gt;In the United States, the FAA has published &lt;a href=&quot;https://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5300-13&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advisory Circular 150/5300-13A, Airport Design&lt;/a&gt; , which includes standards and recommendations for airport design, including parallel runway separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;For simultaneous landings and takeoffs using VFR, the minimum&#xA;separation between &lt;em&gt;centerlines&lt;/em&gt; of parallel runways is 700 feet (213&#xA;m).&quot;&lt;/li&gt;&#xA;&lt;li&gt;For simultaneous IFR operations, &quot;Dual simultaneous precision&#xA;instrument approaches are normally approved on parallel runway&#xA;centerline separation of 4,300 feet (1311 m). On a case-by-case&#xA;basis, the FAA will consider proposals utilizing separations down to&#xA;a minimum of 3,000 feet (914 m) where a 4,300 foot (1311 m)&#xA;separation is impractical. This reduction of separation requires&#xA;special high update radar, monitoring equipment, etc.&quot; Note:&#xA;Simultaneous Offset Instrument Approaches allow as little as 750 ft&#xA;between runway centerlines.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;International regulations do differ. ICAO have their own standards. &lt;a href=&quot;http://www.icao.int/safety/Implementation/Library/Manual%20Aerodrome%20Stds.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is an example&lt;/a&gt; of a document which prescribes airport standards compliant to ICAO Annex 14.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2018-01-10T22:59:05.177" LastActivityDate="2018-01-10T22:59:05.177" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12940" PostTypeId="2" ParentId="12930" CreationDate="2015-02-27T03:37:17.753" Score="18" Body="&lt;p&gt;That distinctly squarish shape looks like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Short_SC.7_Skyvan&quot;&gt;Short SC-7 Skyvan 3-100&lt;/a&gt;, especially since the registration on the photo from below is visible: &lt;a href=&quot;http://www.airliners.net/search/photo.search?regsearch=G-BEOL&quot;&gt;G-BEOL&lt;/a&gt;. &#xA; - &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uw9yd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Short_skyvan_sc-7_g-beol_cotswoldairshow_2010_arp.jpg&quot;&gt;WikiPedia&lt;/a&gt; - Author: Adrian Pingstone)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2117" LastEditorUserId="572" LastEditDate="2015-02-27T06:51:52.380" LastActivityDate="2015-02-27T06:51:52.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12941" PostTypeId="2" ParentId="12932" CreationDate="2015-02-27T06:42:06.993" Score="13" Body="&lt;p&gt;No, it should not be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Twin antennae, as you have shown, are balanced and fed into a balun (&lt;strong&gt;BAL&lt;/strong&gt;anced to &lt;strong&gt;UN&lt;/strong&gt;balanced) to feed the single transmission line to the receiver.   Together, they provide the correct impedance for the aerial system.  With an antenna broken, it is likely that the impedance of the circuit is wrong and therefore, the input to the receiver is, at best, suspect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[GUESSWORK]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's impossible to predict the indicated behaviour without knowing precise details of the aerial fit but a reasonable guess would be that the standing wave ratio in the feed will be altered and therefore, a phase error will be introduced.  The magnitude of the error will vary in proportion to the sine of the actual phase angle so my guess would be that the bearing will be accurate when due South or North of the VOR then increasingly inaccurate as you move round with an maximum error at 90 or 270.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early in the morning when I first wrote this but I think I am wrong about being accurate due North or due South.  It will be accurate &lt;em&gt;somewhere&lt;/em&gt; on the compass and at 180 degrees opposite to that, with increasing inaccuracy as you move towards 90 degrees away from that somewhere.  Only calibration would tell you where the somewhere is.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-02-27T08:17:03.253" LastActivityDate="2015-02-27T08:17:03.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12942" PostTypeId="2" ParentId="12932" CreationDate="2015-02-27T06:59:44.020" Score="4" Body="&lt;p&gt;The literal answer is, who knows? The only way to find out for sure would be to calibrate the VOR and observe the deviation - if any - from the expected readings. The instrument manufacturer might have some general guidance, but no one can predict the results of physical damage accurately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But having said that, it doesn't really matter anyway: you shouldn't be doing anything that requires a VOR if you know that the equipment is broken. Even if it still &lt;em&gt;seems&lt;/em&gt; to be accurate despite the missing antenna, what happens if you lose the other antenna? Or some broken wiring starts causing intermittent false readings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And although this is getting away from the exact question that you asked, there are regulations to consider. You didn't mention a specific jurisdiction, but let's assume US/FAA for now, I'm guessing the general rules are very similar in most places. If you're VFR then you don't need a functioning VOR anyway: by definition, you will never be relying on it for anything because you're navigating visually. It might be &lt;em&gt;helpful&lt;/em&gt; to have a VOR in VFR, but it isn't &lt;em&gt;required&lt;/em&gt;. (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=562af4da4881a07f26d824dcb1eb1b59&amp;amp;node=se14.3.121_1349&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.349&lt;/a&gt; does allow for VFR flights on routes where you can't use pilotage, but it also requires two independent navigation instruments.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if you're IFR then it would probably be illegal for you to rely on a VOR that you know is damaged. 14 CFR 91.205 &lt;a href=&quot;https://aviation.stackexchange.com/questions/1378/what-are-the-faa-requirements-for-an-aircraft-to-be-ifr-certified&quot;&gt;requires&lt;/a&gt; &quot;navigation equipment suitable for the route to be flown&quot;, and I think it would be difficult to convince the FAA that a VOR with a broken antenna is suitable for navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the most basic point of all is that relying on broken equipment is just dangerous, especially for an instrument approach where you're relying on the accuracy of the instruments to prevent you from colliding with the ground or an obstacle. In my opinion, taking that chance would show very poor decision-making and general airmanship.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-02-27T06:59:44.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12943" PostTypeId="2" ParentId="12925" CreationDate="2015-02-27T07:32:15.730" Score="8" Body="&lt;p&gt;If the airport you're based at has federal grant obligations (basically if they've taken money from the &lt;a href=&quot;https://www.faa.gov/airports/aip/&quot; rel=&quot;noreferrer&quot;&gt;Airport Improvement Program&lt;/a&gt;) then being a &quot;flying club&quot; by the FAA's definition entitles you (as a group) to the same rights as any other operator at the field (like the right to fuel your aircraft with fuel you buy yourself &amp;amp; have trucked in, or the right to do maintenance on the aircraft), subject to the same rules and regulations the airport lays down for all operators.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest material difference is that &quot;flying clubs&quot; aren't considered to be &quot;commercial&quot; ventures by the FAA (and by extension grant-obligted airports).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, let's say you have a flying club &amp;amp; you &quot;charge&quot; $50/hr for the use of one of the planes, and your airport management decides that since you're charging money for the use of the planes you're a commercial venture, and need to have commercial insurance and the like.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you meet the FAA definition of a &quot;Flying Club&quot; and the airport has federal grant obligations you can ask your local FSDO to step in and effectively tell the airport management to get stuffed - as a flying club you're treated more like an individual than a commercial business, and the airport is not allowed to impose those commercial requirements on you.&lt;br&gt;&#xA;If you &lt;em&gt;don't&lt;/em&gt; meet that definition the FAA won't intervene on your behalf (as far as they're concerned you &lt;em&gt;are&lt;/em&gt; a rental outfit / commercial FBO at that point and the airport is correct in treating you as one).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that you can still call yourself a &quot;flying club&quot; even if you don't meet the FAA's definition -- I belong to a flying club that has no aircraft (we're just a bunch of folks who like to talk about flying and organize the occasional fly-out event or safety seminar - some of us own planes, and some rent from local FBOs), and it doesn't really matter to us that we don't meet the FAA definition of a flying club because we don't have any interaction with the airport where that designation would benefit us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're the kind of organization that has aircraft available for the use of your members however it probably makes sense to ensure that you're organized &amp;amp; run in such a way as to meet the FAA definition of a flying club.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-02-27T14:23:18.713" LastActivityDate="2015-02-27T14:23:18.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12947" PostTypeId="1" CreationDate="2015-02-27T10:16:52.237" Score="9" ViewCount="5563" Body="&lt;p&gt;The recent crash of a Taiwan aircraft, got me thinking, do aircraft have built in siren, which can warn people on the ground of a possible crash to give them some headway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that is not practicable or feasible, then what solutions are feasible, or one should abandon the idea altogether and think of making planes safer in the first place?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="755" LastEditDate="2015-02-28T23:55:55.887" LastActivityDate="2015-04-11T06:15:28.367" Title="Do aircraft have siren to warn public in case of a crash over land?" Tags="&lt;emergency&gt;&lt;aircraft-systems&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12948" PostTypeId="2" ParentId="12947" CreationDate="2015-02-27T10:26:57.060" Score="19" Body="&lt;p&gt;No they don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think about it, it is very rare for an aircraft to crash into a built-up area. People on the ground would have very little time to hear a siren from an aircraft approaching at a hundred miles per hour or more. Anyone hearing it might be as likely to run into the path of the aircraft rather than run away from it.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-02-27T10:26:57.060" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12949" PostTypeId="2" ParentId="12947" CreationDate="2015-02-27T10:30:54.113" Score="6" Body="&lt;p&gt;No they don't, crashes over land where the plane was stable enough to provide enough warning to the people on the ground are &lt;strong&gt;very&lt;/strong&gt; rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only incident that would have benefited from it which comes to mind is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow&quot;&gt;gimli glider&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="755" LastEditDate="2015-02-28T23:52:58.437" LastActivityDate="2015-02-28T23:52:58.437" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12950" PostTypeId="2" ParentId="12947" CreationDate="2015-02-27T10:54:35.447" Score="6" Body="&lt;p&gt;No, and even if they did you would probably not hear it. Engine noise should be enough to alert someone who is paying attention, but the truth is that the average pedestrian has no cognizance of unusual noises.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the odds of hitting a pedestrian are extremely remote. Most people move around in cars. Unless you are landing on a park or a beach there will generally be noone around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did hear of one case a couple of years ago where a guy ran out of fuel and landed on a beach and killed a jogger. The jogger didn't hear him because he was wearing headphones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you come down it all happens really fast. A pedestrian, even with a lot of warning would have to be paying attention, be alert and react right away. Most people are absorbed in what they are doing and a siren going off 1000 feet away and 300 feet up is not going to be on their radar.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-02-27T10:54:35.447" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="12951" PostTypeId="2" ParentId="12928" CreationDate="2015-02-27T12:28:15.183" Score="7" Body="&lt;p&gt;Sounds like there was no fire at the accident site so that's good.&lt;/p&gt;&#xA;&lt;p&gt;It is possible that a mixture of 100LL and JetA (say 3/4 tank of 100LL topped off with JetA) could have passed the smell test and color test during sumping but still have caused the accident.&lt;/p&gt;&#xA;&lt;p&gt;Possibly the Avgas evaporated quickly at the scene leaving only the jet fuel lingering for the hazmat responder to smell. So even a partial mixture could have done it.&lt;/p&gt;&#xA;&lt;p&gt;However, if you pulled up to any arbitrary FBO or self service rig to fuel your aircraft, you would not be able to get the JetA nozzle to fit in your tank. The following is an excerpt from this wiki page: &lt;a href=&quot;http://en.wikipedia.org/wiki/Aviation_fuel&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://en.wikipedia.org/wiki/Aviation_fuel&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Because of the danger of confusing the fuel types, precautions are&#xA;taken to distinguish between avgas and jet fuel beyond clearly marking&#xA;all containers, vehicles, and piping. The aperture on fuel tanks of&#xA;aircraft requiring avgas cannot be greater than 60 millimetres in&#xA;diameter. Avgas is often dyed and is dispensed from nozzles with a&#xA;diameter of 40 mm (49 mm in the USA).[7] [8]&lt;/p&gt;&#xA;&lt;p&gt;Jet fuel is clear to straw-colored, and is dispensed from a special&#xA;nozzle called a J spout that has a rectangular opening larger than 60&#xA;mm diagonally, so as not to fit into avgas ports. However, some jet&#xA;and turbine aircraft, such as some models of the Astar helicopter,&#xA;have a fueling port too small for the J spout, and thus require a&#xA;smaller nozzle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here is a graphic showing the two spout sizes:&lt;br /&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/42qli.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Simply put, a JetA fueling nozzle will not fit in the aircraft tank's filler neck. So if there was a fueling mishap, it almost needed to be done by the operator with a homebuilt self fueling rig in his hangar.&lt;/p&gt;&#xA;&lt;p&gt;Side note: In the late 80s or early 90s when I owned an FBO with a maintenance shop, the Chevron facility in Richmond CA had a refinery valve mishap and filled several tanker trucks with avgas while JetA was leaking into the delivery apparatus. There were many dozens of piston aircraft fueled by the time they discovered and remedied it. The FAA issued an AD against all aircraft that got some of this fuel and Chevron bought each owner an overhaul.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-27T13:22:34.473" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12952" PostTypeId="1" AcceptedAnswerId="12954" CreationDate="2015-02-27T13:35:49.190" Score="55" ViewCount="22509" Body="&lt;p&gt;What does &quot;arming a door&quot; mean?  Is the orange tape that's applied over a window related, perhaps as an indicator to people outside that the door is armed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zJrM1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zJrM1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7452" LastEditorUserId="24487" LastEditDate="2018-06-13T20:27:53.923" LastActivityDate="2019-03-31T15:53:32.233" Title="What does it mean for a door to be armed?" Tags="&lt;safety&gt;&lt;equipment&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="12953" PostTypeId="2" ParentId="12952" CreationDate="2015-02-27T13:39:22.167" Score="12" Body="&lt;p&gt;When the door is armed, the slide will deploy when the door is opened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tape is indeed an indicator to people outside that the door is armed.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="946" LastEditDate="2015-02-27T14:13:39.593" LastActivityDate="2015-02-27T14:13:39.593" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12954" PostTypeId="2" ParentId="12952" CreationDate="2015-02-27T13:41:13.087" Score="62" Body="&lt;p&gt;If a door is put into &lt;em&gt;armed mode&lt;/em&gt;, it will trigger the &lt;a href=&quot;http://en.wikipedia.org/wiki/Evacuation_slide&quot; rel=&quot;noreferrer&quot;&gt;evacuation slide&lt;/a&gt; when the door is opened.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Prior to departure (usually before engine startup), all the aircraft doors are placed into the armed (or automatic) mode by the cabin crew. Methods of arming vary from aircraft to aircraft, but ultimately the girt bar (a metal bar attached to the door end of the slide) is physically attached to brackets either in or adjacent to the door sill.&lt;br&gt;&lt;br&gt;[...]If a rapid evacuation is required and the doors are opened while &amp;quot;armed&amp;quot;, the opening of the door pulls the slide pack out of the bustle (because the girt bar is physically attached to the aircraft floor)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is also the reason for the famous &lt;a href=&quot;http://www.askthepilot.com/how-to-speak-airline/&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;All doors in flight&lt;/em&gt; announcement&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;DOORS TO ARRIVAL AND CROSSCHECK “Flight attendants, doors to arrival and crosscheck.”&lt;/p&gt;&#xA;&lt;p&gt;Meaning: Occasionally heard as “disarm your doors and crosscheck,” and announced by the lead flight attendant or purser as a plane approaches the gate. The intent is to verify disarming of the emergency escape slides attached to the doors. When armed, a slide will automatically deploy the instant its door is opened. Disarmed, it needs to be deployed manually. On departure the slides are armed to facilitate an emergency evacuation. (You might hear this as “doors to automatic.”) Upon docking, they’re disarmed to keep them from billowing into the boarding tunnel or onto the apron during servicing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The orange or yellow tape is a visual indicator for ground workers or ramp agents that the doors are armed or not armed. The visual indicator can vary, it can also be built into the door lock mechanism, triggering a visual indicator externally if the door is locked and armed. In the following picture, the orange tape is not strapped over the window, which should indicate an unarmed door. In the video that this image is taken from, the flight attendant has just locked and possibly armed the door, the other flight attendant would place the orange tape over the door window during &amp;quot;cross-check&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pofac.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&#xA;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.youtube.com/watch?v=H2gYxDoGDrQ&quot; rel=&quot;noreferrer&quot;&gt;YouTube &amp;quot;B757-200 Door Closing&amp;quot;&lt;/a&gt; - Author: Exupery747)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-02-27T16:54:30.417" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12955" PostTypeId="2" ParentId="12947" CreationDate="2015-02-27T13:51:41.233" Score="32" Body="&lt;p&gt;I understand where you are at with this, I'm going to start off with a bit of math to show how it's not workable. Commercial airliners move quickly, even in a controlled glide one is going close to 3 miles (4-5 km) per minute. To give people on the ground enough useful warning to perhaps find some sort of cover you would need to give at least 20 seconds. This siren would have to be able to penetrate the walls of buildings and houses and cut through the background noise of a built up area at least a mile ahead. This is a very powerful siren and you'll have the following challenges:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At close range you would deafen anyone nearby, injuring the people you are trying to warn&lt;/li&gt;&#xA;&lt;li&gt;The mechanism to generate this siren would likely be large, heavy, and challenging to design into an aircraft frame&lt;/li&gt;&#xA;&lt;li&gt;You would need a great deal of mechanical or electrical power to generate that amount of noise. If you have no engine power you won't be able to sound the siren, and if your engines are working you won't need to as the engines make very good sirens already&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are very, very few cases where a siren such as this would save very few lives compared to justify the costs. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-02-27T13:51:41.233" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="12956" PostTypeId="1" AcceptedAnswerId="12957" CreationDate="2015-02-27T17:32:08.053" Score="18" ViewCount="128017" Body="&lt;p&gt;When looking at different aircraft's specifications or in POHs/AFMs, there are several different weights of the aircraft mentioned (e.g. maximum take-off weight, maximum landing weight, operating empty weight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do they mean and how they are different?&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2019-07-10T07:07:08.713" Title="What are different types of weights of an aircraft?" Tags="&lt;aircraft-design&gt;&lt;weight-and-balance&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="12957" PostTypeId="2" ParentId="12956" CreationDate="2015-02-27T17:32:08.053" Score="23" Body="&lt;p&gt;The different terms represent different weights or masses&lt;sup&gt;1&lt;/sup&gt;. For each flight, the weights are taken into account for several reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A brief description about these is below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Manufacturer%27s_empty_weight&quot; rel=&quot;noreferrer&quot;&gt;Manufacturer's empty weight&lt;/a&gt; (MEW)&lt;/strong&gt;&lt;br&gt;&#xA;Also called &lt;em&gt;Manufacturer's Weight Empty (MWE)&lt;/em&gt; or &lt;em&gt;Licensed Empty Weight&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the weight of the aircraft &quot;as built&quot; and includes the weight of the structure, power plant, furnishings, installations, systems and other equipment that are considered an integral part of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This excludes any baggage, passengers, or usable fuel&lt;sup&gt;2&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Zero-fuel_weight&quot; rel=&quot;noreferrer&quot;&gt;Zero-fuel weight&lt;/a&gt; (ZFW)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the total weight of the airplane &lt;em&gt;and&lt;/em&gt; all its contents (including unusable fuel), but excluding the total weight of the usable fuel on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a flight progresses and fuel is consumed, the total weight of the airplane reduces, but the ZFW remains constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maximum zero fuel weight (MZFW) is the maximum weight allowed before usable fuel and other specified usable agents (engine injection fluid, and other consumable propulsion agents) are loaded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Operating_empty_weight&quot; rel=&quot;noreferrer&quot;&gt;Operating empty weight&lt;/a&gt; (OEW)&lt;/strong&gt; (Roughly equivalent to &lt;em&gt;basic empty weight&lt;/em&gt; on light aircraft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the basic weight of an aircraft including the crew, all fluids necessary for operation such as engine oil, engine coolant, water, unusable fuel and all operator items and equipment required for flight but excluding usable fuel and the payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Payload&quot; rel=&quot;noreferrer&quot;&gt;Payload&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the carrying capacity of an aircraft. It includes cargo, people, extra fuel. In the case of a commercial airliner, it may refer only to revenue-generating cargo or paying passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;noreferrer&quot;&gt;Maximum takeoff weight&lt;/a&gt; (MTOW)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off&lt;sup&gt;3&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;noreferrer&quot;&gt;Regulated takeoff weight&lt;/a&gt; (RTOW)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on different factors (e.g. flap setting, altitude, air temperature, length of runway), RTOW or &lt;em&gt;maximum permissible takeoff weight&lt;/em&gt; varies for each takeoff. It can never be higher than MTOW. More information is on &lt;a href=&quot;https://aviation.stackexchange.com/a/44144/65&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_landing_weight&quot; rel=&quot;noreferrer&quot;&gt;Maximum landing weight&lt;/a&gt; (MLW)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This maximum weight at which an aircraft is permitted to land&lt;sup&gt;3&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image depicts takeoff weight components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DT38B.png&quot; alt=&quot;Weights&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Takeoff_weight_diagram.svg&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;&lt;sup&gt;Image Source&lt;/sup&gt;&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Maximum_ramp_weight&quot; rel=&quot;noreferrer&quot;&gt;Maximum ramp weight&lt;/a&gt; (MRW)&lt;/strong&gt;&lt;br&gt;&#xA;&lt;em&gt;also called maximum taxi weight (MTW)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the maximum weight authorized for maneuvering (taxiing or towing) an aircraft on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_gross_weight&quot; rel=&quot;noreferrer&quot;&gt;Aircraft gross weight&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the total aircraft weight at any moment during the flight or ground operation. This decreases during flight due to fuel and oil consumption.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: As &lt;a href=&quot;https://aviation.stackexchange.com/questions/12956/what-are-different-types-of-weights-of-an-aircraft/12957?noredirect=1#comment28101_12957&quot;&gt;mentioned (below in comments by SentryRaven)&lt;/a&gt;, several recent references use the term &lt;em&gt;mass&lt;/em&gt; instead of &lt;em&gt;weight&lt;/em&gt;. Having a Physics background, I tend to agree and know the difference between &lt;a href=&quot;http://en.wikipedia.org/wiki/Mass_versus_weight&quot; rel=&quot;noreferrer&quot;&gt;weight and mass&lt;/a&gt;. I did not use &lt;em&gt;mass&lt;/em&gt; as most of the references I included referred mass as weight. However, using correct terminology, all the weights mean mass. Thanks &lt;a href=&quot;https://aviation.stackexchange.com/users/572/sentryraven&quot;&gt;SentryRaven&lt;/a&gt; for pointing it out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt;: &lt;strong&gt;What is the different between usable fuel and unusable fuel?&lt;/strong&gt;&lt;br&gt;&#xA;&lt;em&gt;Usable fuel&lt;/em&gt; is the fuel on board an aircraft that can actually be used by its engines. The small amount of fuel that cannot be drained from the tanks is the &lt;em&gt;unusable fuel&lt;/em&gt;. For calculation of range, usable fuel is used. For weight and balance total fuel (usable + unusable) is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt;: This restriction is due to structural, design or operational limitations.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2017-11-15T16:09:40.097" LastActivityDate="2017-11-15T16:09:40.097" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="12958" PostTypeId="1" AcceptedAnswerId="12960" CreationDate="2015-02-27T19:12:05.270" Score="17" ViewCount="28555" Body="&lt;p&gt;What are the material types account for most of the empty weight of an airplane (Boeing 747), besides aluminum or its alloys used in fuselage? &lt;/p&gt;&#xA;" OwnerUserId="7456" LastEditorUserId="3054" LastEditDate="2015-02-27T20:05:09.610" LastActivityDate="2019-02-10T03:34:46.877" Title="What materials make up most of the weight of an aircraft?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12959" PostTypeId="2" ParentId="12958" CreationDate="2015-02-27T19:32:46.427" Score="6" Body="&lt;p&gt;A general breakdown by material type isn't really useful (or possible) because the heaviest components of most aircraft are composed of multiple materials, and not all aircraft are built of the same materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The heaviest component of &lt;em&gt;most&lt;/em&gt; airplanes is the fuselage. This is predominantly aluminum, but possibly composite in newer aircraft (Cirrus SR-22, Boeing 787), and some aircraft have multiple materials used (e.g. Mooneys have an aluminum skin, but a steel frame/cage, and &quot;tube-and-fabric&quot; airplanes use cloth and dope stretched over a (typically steel) frame).&lt;br&gt;&#xA;While the alloy (or composite) used for the fuselage is probably relatively light compared to say a car's frame &amp;amp; body it's usually the &lt;em&gt;largest part&lt;/em&gt; of an aircraft, and thus the heaviest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number two component on an airplane is the engine (or engines) -- the engine may even be the heaviest component of some aircraft (&lt;a href=&quot;http://en.wikipedia.org/wiki/Ultralight_aviation&quot;&gt;Ultralights&lt;/a&gt; and some tube-and-fabric aircraft).&lt;br&gt;&#xA;As with the fuselage an engine is often comprised of multiple metal alloy: crank shafts and cams tend to be steel, lifter faces are often cast iron, the crankcase tends to be aluminum, pistons are usually &lt;em&gt;both&lt;/em&gt; (a steel barrel mated to an aluminum head), and various alloys are used in bearings and valve guides.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As an example if we look at a Piper Cub the heaviest alloy is probably steel (the fuselage tubing, crankcase, and camshaft are all steel). Number two is probably aluminum (the engine crankcase, pistons, and cylinder heads are aluminum, as are the wing ribs and &lt;em&gt;possibly&lt;/em&gt; the spars). Number three &lt;em&gt;might&lt;/em&gt; be wood (if the spars were never converted to aluminum), but is more likely the fabric (and dope/paint) used to cover the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a different example, consider the &lt;a href=&quot;http://en.wikipedia.org/wiki/De_Havilland_Mosquito&quot;&gt;de Haviland Mosquito&lt;/a&gt;: The heaviest component of this aircraft is unquestionably wood (as the aircraft is constructed almost entirely of wood), and the number two item is probably aluminum or iron (from the engines &amp;amp; propellers).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-02-27T19:32:46.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12960" PostTypeId="2" ParentId="12958" CreationDate="2015-02-27T19:55:50.443" Score="27" Body="&lt;p&gt;Besides aluminum alloys, most of an airplane's weight is steel, titanium, and composites. Here is a chart comparing the 747 and 777 structural weight, with a breakdown &lt;a href=&quot;http://www.ndt.net/article/wcndt00/papers/idn904/idn904.htm&quot; rel=&quot;noreferrer&quot;&gt;typical for similar airliners&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IbUh4.jpg&quot; alt=&quot;747 and 777 materials breakdown&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://hsc.csu.edu.au/engineering_studies/focus/aero/2580/aluminium_answers.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Steel&lt;/strong&gt; is used in components where strength or part life is most important, like landing gear and other important structural elements, as well as many fasteners. &lt;strong&gt;Titanium&lt;/strong&gt; is used where weight and high temperature are important, such as around the engines. &lt;strong&gt;Composites&lt;/strong&gt; are traditionally used for many less-structural applications such as panels and fairings, but may also be used in the empennage (tail surfaces) or on the interior as floor beams. &lt;strong&gt;Other&lt;/strong&gt; materials will include alloys like nickel, as well as specialty materials like rubber, plastic, and fabric, which are used mostly in the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;New aircraft like the 787 and &lt;a href=&quot;http://www.sec.gov/Archives/edgar/data/717605/000110465908021748/a08-9785_1defa14a.htm&quot; rel=&quot;noreferrer&quot;&gt;A350&lt;/a&gt; use composites much more extensively, replacing much of the aluminum. Titanium is also used more in these aircraft because it does not tend to corrode in contact with carbon fiber composite like aluminum does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MTlNV.gif&quot; alt=&quot;787 materials breakdown&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://modernairliners.com/Boeing787_files/Specifications.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Federico pointed out that the two graphics differ in the amount of aluminum on the 777 (70% on the first vs. 50% on the second), because the first chart shows only structural weight, while the second is overall.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-03-04T16:08:46.307" LastActivityDate="2015-03-04T16:08:46.307" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="12961" PostTypeId="2" ParentId="12956" CreationDate="2015-02-27T21:06:48.507" Score="10" Body="&lt;p&gt;Read this from left to right, from detailed to generalized. Boxes on the right sum up the separate items which they run across.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6C6ry.png&quot; alt=&quot;diagram of mass definitions&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum landing weight is what the manufacturer has certified for landings. Generally, this is MTOW minus some fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that every manufacturer has his own standard and might draw the lines between the different weight groups differently. Say, for one the engine quadrant is part of the propulsion system, whereas the other sees it as part of the control system.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T09:28:38.287" LastActivityDate="2015-05-10T09:28:38.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12963" PostTypeId="1" AcceptedAnswerId="12968" CreationDate="2015-02-28T03:33:31.693" Score="22" ViewCount="29067" Body="&lt;p&gt;During WWII, there were a number of twin-fuselage aircraft (notably bombers but some fighters). They were made by apparently combining two existing single-fuselage aircraft bodies together:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LhnF3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Twin-fuselages seemed to disappear after the 1960s but  recently, Virgin Galactic has come out with a twin-fuselage aircraft, the WhiteKnightTwo. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/npyZE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the Virgin design as the space module (SpaceShipTwo) is designed to fit between the two fuselages. But aside from that special case, are there any advantages to twin-fuselage aircraft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was their design and introduction in the 1930s-1950s merely a strange historical accident (and if so, what was the reason d'etre then) or do they currently or potentially have advantages over single-fuselages such that we might see their return?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-02-28T04:46:41.730" LastActivityDate="2021-01-19T08:45:19.803" Title="What are the advantages of twin-fuselage aircraft?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12964" PostTypeId="2" ParentId="12963" CreationDate="2015-02-28T08:33:56.100" Score="7" Body="&lt;p&gt;The F-82 in the top picture is the result of a wartime need for a long-range fighter-bomber. It takes a &lt;em&gt;long&lt;/em&gt; time to design and tool up for a new aircraft, it takes rather less time to use your existing tools and rearrange the pieces you already have. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long range means more fuel, that means more power, and in 1945 that meant a second engine. So, lets take two of those, build the center part with existing tools and we're done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more detailed explanation can be found on Wikipedia.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-02-28T08:33:56.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12965" PostTypeId="2" ParentId="12963" CreationDate="2015-02-28T09:07:59.433" Score="13" Body="&lt;p&gt;As paul mentioned, the dual-fuselage fighters of WWII were primarily just ways to build a longer-range fighter much more quickly than starting with a completely new airframe design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang&quot; rel=&quot;noreferrer&quot;&gt;F-82&lt;/a&gt; specifically was designed to escort long-range bombers on bombing missions over Japan from U.S. bases in the Pacific (the Solomon Islands or the Philippines, for example.) However, the war ended before it entered service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Germans also designed the twin-fuselage &lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_111#He_111Z&quot; rel=&quot;noreferrer&quot;&gt;He 111Z&lt;/a&gt; as a tug to tow troop-drop gliders in WWII. Again, this was much faster to get to production than designing a new aircraft. Obviously, time-to-production is a very big consideration when you're in the middle of an ongoing war and need some specific capability for the war. In such cases, earlier service entry may override a more elegant design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another use that &lt;a href=&quot;http://en.wikipedia.org/wiki/Twin-fuselage_aircraft#Early_seaplanes&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; mentions for dual-fuselage aircraft was for early seaplanes. In these cases, the dual fuselages added stability on the water, similar to the way pontoons or outriggers are used, especially for flying boat designs where the aircraft uses the bottom of the fuselage as a hull in the water rather than using separate floats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, as you mentioned, the most recent uses of dual-fuselage aircraft have been for space launch vehicle carriers, such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_White_Knight_Two&quot; rel=&quot;noreferrer&quot;&gt;White Knight Two&lt;/a&gt; and the ridiculously-massive &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_Stratolaunch&quot; rel=&quot;noreferrer&quot;&gt;Scaled Composites Roc&lt;/a&gt; built for &lt;a href=&quot;http://www.stratolaunch.com/&quot; rel=&quot;noreferrer&quot;&gt;Stratolaunch Systems&lt;/a&gt;. The reasoning here is that you obviously want the payload that you're going to be dropping mid-flight to be along the centerline of the aircraft for &lt;a href=&quot;http://en.wikipedia.org/wiki/Center_of_gravity_of_an_aircraft&quot; rel=&quot;noreferrer&quot;&gt;CG&lt;/a&gt; reasons. When said payload is something the size of a space launch vehicle, a dual-fuselage design allows you to leave a really big space to mount the launch vehicle while still keeping the weight balanced laterally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scaled Composites Roc carrier aircraft:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/oljBE.png&quot; alt=&quot;Scaled Composites Roc carrier aircraft&quot;&gt;&#xA;Image source: &lt;a href=&quot;http://en.wikipedia.org/wiki/File:Stratolaunch_comparison.svg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-02-28T09:07:59.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12967" PostTypeId="1" CreationDate="2015-02-28T09:58:18.677" Score="17" ViewCount="2553" Body="&lt;p&gt;What happens when a commercial airline pilot wants to remove himself from a flight a short time before takeoff (say an hour or less)? He obviously can't be forced to fly, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/63/what-to-do-if-the-captain-smells-like-alcohol&quot;&gt;there may be very good reasons he shouldn't&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the penalty for the pilot?&lt;br&gt;&#xA;What are the passengers told if it &lt;em&gt;is&lt;/em&gt; something embarrassing, like a drunk pilot?&lt;br&gt;&#xA;How long does it take to get a replacement pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surely the exact answers depend on the airline, but in general what happens? What regulations govern this situation?&lt;/p&gt;&#xA;" OwnerUserId="3951" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-01T22:38:35.343" Title="What happens when an airline pilot decides not to fly at the last minute?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;pilots&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="12968" PostTypeId="2" ParentId="12963" CreationDate="2015-02-28T10:08:45.700" Score="15" Body="&lt;p&gt;Depending on the design, one of three advantages made designers choose a twin-boom layout:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;No structure directly aft of the fuselage, which helped to integrate the propulsion, or &lt;a href=&quot;http://en.wikipedia.org/wiki/Fairchild_C-82_Packet&quot; rel=&quot;noreferrer&quot;&gt;improved access to the cargo area&lt;/a&gt;, or improved &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_189&quot; rel=&quot;noreferrer&quot;&gt;pilot vision&lt;/a&gt;,&lt;/li&gt;&#xA;&lt;li&gt;Smaller overall surface area for &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_P-38_Lightning&quot; rel=&quot;noreferrer&quot;&gt;two-engine aircraft&lt;/a&gt;, or&lt;/li&gt;&#xA;&lt;li&gt;Shorter development time for high-performance aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are two groups of twin boom designs: Those which were designed that way from the outset, and those which were later derived from single-fuselage designs. You could add a third group, those with two distinct fuselages and an offset pilot position, but an offset cockpit could also be a result of other design considerations. Examples are the &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Ju_322&quot; rel=&quot;noreferrer&quot;&gt;Junkers 322&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_141&quot; rel=&quot;noreferrer&quot;&gt;Blohm&amp;amp;Voss BV 141&lt;/a&gt;, both single-fuselage designs with an offset cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first group comprises aircraft like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airco_DH.2&quot; rel=&quot;noreferrer&quot;&gt;D.H. 2&lt;/a&gt;, the Saab 21 (picture below, &lt;a href=&quot;http://www.airwar.ru/image/idop/fww2/j21/j21-4.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gotha_Go_242&quot; rel=&quot;noreferrer&quot;&gt;Gotha Go-242&lt;/a&gt;. Here the designers wanted to create space for the propeller or a loading ramp. Also, &lt;a href=&quot;http://en.wikipedia.org/wiki/De_Havilland_Vampire&quot; rel=&quot;noreferrer&quot;&gt;some early jet aircraft&lt;/a&gt; used a two-boom layout to keep the tail structure free of the jet blast. The advantage is obvious: No structure at the rear fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PuI3K.jpg&quot; alt=&quot;Saab-21&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second group arose due to the performance requirements of modern, all-metal, stressed-skin designs with cantilevered wings. Remember that at the beginning of the 1930s fighters were still biplanes (&lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Fury&quot; rel=&quot;noreferrer&quot;&gt;Hawker Fury&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_51&quot; rel=&quot;noreferrer&quot;&gt;Heinkel He-51&lt;/a&gt;), and new designs like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Caudron_C.460&quot; rel=&quot;noreferrer&quot;&gt;Caudron 460&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_108&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt Bf-108&lt;/a&gt; showed that sleek aerodynamics and high wing loading were the way ahead. However, unlocking the performance potential possible with these designs required much more powerful engines. The engine manufacturers could increase power output only slowly, so a number of designs (&lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_P-38_Lightning&quot; rel=&quot;noreferrer&quot;&gt;Lockheed P-38&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_110&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt Me-110&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Bristol_Beaufighter&quot; rel=&quot;noreferrer&quot;&gt;Bristol Beaufighter&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_P-61_Black_Widow&quot; rel=&quot;noreferrer&quot;&gt;Northrop P-61&lt;/a&gt;) tried to use two engines. Since there were two engines already with a big space requirement for the turbocharger, Lockheed decided to use a two-tailboom design. Here the advantage was a smaller overall surface area to house two engines, their coolers and turbochargers, and the pilot (picture below, &lt;a href=&quot;http://www.thunderace.org/images/P38/P38.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/g0SNu.jpg&quot; alt=&quot;P-38 in flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the war, again the requirement for more powerful aircraft arose, and to avoid the delay of a fully new design, existing aircraft were combined, shortening the development time greatly. The first of those was the &lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_111#He_111H_and_its_variants&quot; rel=&quot;noreferrer&quot;&gt;Heinkel He-111 Z&lt;/a&gt; (for Zwilling = Twin), which added a fifth engine to be able to pull the giant &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_321&quot; rel=&quot;noreferrer&quot;&gt;Me-321 transport glider&lt;/a&gt;. Joining two powerful aircraft was proposed for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_109&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt Bf-109&lt;/a&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_109_variants#Bf_109Z_.22Zwilling.22&quot; rel=&quot;noreferrer&quot;&gt;Bf-109 Z&lt;/a&gt;), the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_309&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt  Me-309&lt;/a&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_609&quot; rel=&quot;noreferrer&quot;&gt;Me 609&lt;/a&gt;), the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Do_335&quot; rel=&quot;noreferrer&quot;&gt;Dornier Do 335&lt;/a&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Do_635&quot; rel=&quot;noreferrer&quot;&gt;Do 635&lt;/a&gt;), the &lt;a href=&quot;http://en.wikipedia.org/wiki/Savoia-Marchetti_SM.92&quot; rel=&quot;noreferrer&quot;&gt;Savoia-Marchetti SM.92&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot; rel=&quot;noreferrer&quot;&gt;North American P-51&lt;/a&gt;, the only one of those to result in an operational aircraft, the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang&quot; rel=&quot;noreferrer&quot;&gt;F-82&lt;/a&gt;. This resulted in an agile aircraft with high speed and high range, which was very useful for escort or reconnaissance tasks. However, only few of those were used operationally, because soon jet aircraft filled that need in a better way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantages of the twin fuselage designs with their offset pilot position is the high radius of roll inertia and the vertical acceleration suffered by the pilot during rolling maneuvers. Especially for a fighter, a fast roll response is the key to success in aerial combat, and a twin fuselage will impose a penalty not suffered by a two-engined aircraft with a central fuselage. This is compounded by the pilot suffering additional vertical acceleration when rolling, which again will reduce the likely roll agility of the twin-fuselage aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Might we see more twin-boom or twin-fuselage designs in the future? Probably only for &lt;a href=&quot;http://en.wikipedia.org/wiki/Rutan_Voyager&quot; rel=&quot;noreferrer&quot;&gt;special purposes&lt;/a&gt;, like the example you have given yourself. Another might be the Kensgaila VK-7, a Lithuanian airfoil testbed which combines two &lt;a href=&quot;http://en.wikipedia.org/wiki/LET_L-13_Blan%C3%ADk&quot; rel=&quot;noreferrer&quot;&gt;Blanik gliders&lt;/a&gt; with a special, exchangeable center section for testing new airfoils under realistic conditions. This one is not even on &lt;a href=&quot;http://en.wikipedia.org/wiki/Twin-fuselage_aircraft&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia's list of twin-fuselage aircraft&lt;/a&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Earlier twin-boom transport aircraft like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Fairchild_C-119_Flying_Boxcar&quot; rel=&quot;noreferrer&quot;&gt;Fairchild C-119&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Nord_Noratlas&quot; rel=&quot;noreferrer&quot;&gt;Nord Noratlas&lt;/a&gt; have given way to conventional layouts with a raised tail to accommodate the rear ramp. Twin-boom and twin-fuselage designs are less stiff and more prone to flutter than conventional configurations, so the conventional design prevailed and will do so in future as well.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-14T07:27:51.750" LastActivityDate="2017-10-14T07:27:51.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12970" PostTypeId="2" ParentId="9411" CreationDate="2015-03-01T03:37:35.347" Score="2" Body="&lt;p&gt;Yes, civilians can fly military aircraft including jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Czech's have sold off a lot of their old &lt;a href=&quot;https://en.wikipedia.org/wiki/Aero_L-39_Albatros&quot; rel=&quot;nofollow&quot;&gt;L-39&lt;/a&gt; trainers and you frequently see them around airfields. I know of one accident where the L-39's nose, which normally carries a radar, had been converted into a luggage compartment and the hatch opened as the guy was taking off and one of his suitcases flew into the left engine with fatal consequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest headache is the ejection seat which is a maintenance nightmare with various legal issues. Also, military jets tend to burn fuel like a son-of-a-bitch, so they can be expensive to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of my dreams is to someday own a &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_T-6_Texan_II&quot; rel=&quot;nofollow&quot;&gt;Texan&lt;/a&gt;, which would be so cool (think: cruising at 300 knots, wowzers!). Hopefully, Greece will go bankrupt and have to sell off all their Texans cheap, hee hee.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-01T03:37:35.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12971" PostTypeId="2" ParentId="12967" CreationDate="2015-03-01T05:46:33.900" Score="11" Body="&lt;p&gt;If a pilot removes themselves from a flight then the airline will attempt to find another pilot to replace them. Sometimes this can be done almost immediately if someone is available there at the airport (sometimes called &quot;ready reserve&quot; or &quot;airport reserve&quot;). Otherwise another reserve will have to be called from home. The amount of time given to a reserve pilot to appear at the airport varies by airline but is typically around two hours. This is normally called &quot;short call reserve&quot;. If no one is available on short call then the flight will most likely be cancelled. There are other scenarios whereby a pilot can be removed from another flight to operate this one but this is less common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot that removes his/herself from duty may face company discipline depending on the circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are really no relevant government regulations (in the United States, at least) other than those requiring a pilot to be fit for duty (and within legal duty and flight time restrictions).&lt;/p&gt;&#xA;" OwnerUserId="7443" LastActivityDate="2015-03-01T05:46:33.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12972" PostTypeId="1" AcceptedAnswerId="12973" CreationDate="2015-03-01T09:35:19.260" Score="9" ViewCount="878" Body="&lt;p&gt;Following the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12952/what-does-it-mean-for-a-door-to-be-armed&quot;&gt;question&lt;/a&gt; about arming the door, the link states that doors are usually armed before engine start. What if something goes wrong when passengers are already boading with doors un-armed how to escape from the airplane?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-29T13:55:58.587" Title="How to escape from an aircraft if the door is not armed?" Tags="&lt;emergency&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12973" PostTypeId="2" ParentId="12972" CreationDate="2015-03-01T09:58:50.737" Score="13" Body="&lt;p&gt;The door the passengers are loading through is obviously one route, back down the jetway or stairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The door being &quot;armed&quot; does not affect whether it can be opened or not.  When the door is armed, opening it will also automatically inflate the escape slide.  When the door is disarmed, the slide will not inflate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, each door has a manual inflation handle for the escape slide which the crew can use to deploy the slide if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find a non-copyrighted picture to include.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cabincrewexams.com/cabin-crew-trainingaircraftslides/&quot; rel=&quot;nofollow&quot;&gt;You could start here for more information.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-10-29T13:55:58.587" LastActivityDate="2015-10-29T13:55:58.587" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12974" PostTypeId="2" ParentId="12753" CreationDate="2015-03-01T14:47:57.983" Score="16" Body="&lt;p&gt;The factors that are relevant here are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Increasing the bypass ratio is very desirable in order to improve the efficiency of the engine, and for the same amount of thrust, this means increasing the fan diameter.&lt;/li&gt;&#xA;&lt;li&gt;In order to keep the fan mostly subsonic, the fan rotational speed has to decrease with increasing fan diameters. Supersonic fan blade tips are possible and in use, but you lose efficiency and increase noise, so it's desirable to limit this to the outermost area.&lt;/li&gt;&#xA;&lt;li&gt;For the same efficiency, a low-speed turbine requires more stages and therefore more weight compared to a high-speed turbine. Compare the PW1100G's 3-stage LPT (geared) with LEAP-1A's 7-stage LPT (not geared).&lt;/li&gt;&#xA;&lt;li&gt;The only way to decouple the rotational speed of the LPT from the rotational speed of the fan is by using a gearbox.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the long run, this is therefore a question of whether the gearbox is heavier than a slower-turning LPT and whether a possible increase in maintenance costs due to the gearbox is acceptable for the given gain in efficiency or reduction in engine weight. With further increases in engine bypass ratios, the gearbox becomes increasingly attractive. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the short run, this is also a question of whether a company wants to risk developing a completely new component, with potential problems before and after entry into service. Additionally, with a given amount of money and manpower to develop a new engine, management will ask: Where are the engineering hours going to make a bigger difference, in improved fan, compressor, turbine and combution chamber designs/materials/... or in a gearbox design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while, for example, Rolls-Royce does not manufacture a geared turbofan right now, their &quot;UltraFan&quot; research engine project does include a gearbox. I think it's safe to say that it is only a matter of time until most commercial turbofans will include a gearbox.&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="5665" LastEditDate="2015-03-01T14:54:11.920" LastActivityDate="2015-03-01T14:54:11.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12975" PostTypeId="2" ParentId="12972" CreationDate="2015-03-01T15:02:58.207" Score="6" Body="&lt;p&gt;If the passengers are boarding, the stairway or jetway will still be in place, so this would still be the main route to evacuate the aircraft. There is no requirement for the door to be armed and for the slides to be triggered during an evacuation while the aircraft is still &quot;docked&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is an emergency onboard after the stairway or jetway has been removed, but the door not having been armed yet, the evacuation slides can be trigged manually if they are needed.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-03-01T15:02:58.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12977" PostTypeId="1" AcceptedAnswerId="12989" CreationDate="2015-03-01T16:59:17.420" Score="6" ViewCount="2296" Body="&lt;p&gt;I read that the &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56&quot;&gt;CFM56&lt;/a&gt; is based upon the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_F101&quot;&gt;F101&lt;/a&gt;.  Id on't know how true that is, but it generated the following question:  If a larger fan is fitted to a low bypass turbofan, would dry thrust be increased?  Or is it the same amount of thrust produced with less fuel consumption?  That is what I was told on another message board but it doesn't seem to make sense.  Assuming that the proper size turbine is fitted, the same turbine airflow should be turned into more thrust with a larger fan.  Which is correct?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-03-08T09:17:11.993" Title="Can the thrust of a turbofan be increased by increasing bypass ratio?" Tags="&lt;jet-engine&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12978" PostTypeId="2" ParentId="12977" CreationDate="2015-03-01T19:10:56.643" Score="2" Body="&lt;p&gt;The jet engine propulses the aircraft based on moving air behind the aircraft at a higher speed than the airplane. Turbofan tries to move a higher quantity of air at lower speed that is more efficient. That is what is called propulsion efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be easily understood thinking about how can you propulse yourself when you are in a skateboard, will be more efficient if you use your hands over a wall or over something that can slip on floor? The heavier that &quot;thing&quot; the best for your propulsion reaching the building wall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, that's a good concept, but you need to do it!!! For being able to do that you need to connect a turbine at the exhaust of the previous turbine connected mechanically to the new fan of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Easy but no so good...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You are adding a new compressor stage (the fan) in front of the previous stages. So you need to make sure that all your materials are prepared for it.&lt;/li&gt;&#xA;&lt;li&gt;You exhaust of the core might not be properly prepared to the new conditions.&lt;/li&gt;&#xA;&lt;li&gt;Probably external shape of the previous engine is not prepared for a secondary flow.&lt;/li&gt;&#xA;&lt;li&gt;Systems need to be reviewed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In principle, with some modifications, that operation you suggest will work but just if we are talking about small modifications and not going to significant bypass ratio, where modifications will be of the same cost of a complete new engine design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also I see economical difficulties, in the current context there is significant competition for making the lowest comsuption. If you perform what you are proposing you will have an engine optimized for not having secondary flow adapted for secondary flow competing with engines optimized for working with secondary flow. Engine will be unefficient compared with competitors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, you will increase weight and thrust.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-03-01T19:10:56.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12979" PostTypeId="1" AcceptedAnswerId="13008" CreationDate="2015-03-01T20:10:39.247" Score="17" ViewCount="2103" Body="&lt;p&gt;In the Wikipedia article on the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang&quot; rel=&quot;noreferrer&quot;&gt;F-82 Twin Mustang&lt;/a&gt; it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After a month of work North American engineers finally discovered that rotating the propellers to meet in the center on their upward turn created sufficient drag to cancel out all lift from the center wing section, one quarter of the aircraft's total wing surface area. The engines and propellers were then exchanged, with their rotation meeting on the downward turn, and the problem was fully solved&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why did this direction of propeller turn cause this problem?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NdyLa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image source: &lt;a href=&quot;http://www.au.af.mil/au/afhra/wwwroot/photo_galleries/aaf_wwii_vol_vi/Captions/078_Experimental.htm&quot; rel=&quot;noreferrer&quot;&gt;http://www.au.af.mil/au/afhra/wwwroot/photo_galleries/aaf_wwii_vol_vi/Captions/078_Experimental.htm&lt;/a&gt; &#xA;(This image or file is a work of a U.S. Air Force Airman or employee, taken or made as part of that person's official duties. As a work of the U.S. federal government, the image or file is in the public domain.)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="2407" LastEditDate="2015-03-03T14:25:07.377" LastActivityDate="2018-07-29T14:47:57.463" Title="Why did upward turning propellers in the F-82 Twin Mustang cause a loss of lift in the center wing section?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12980" PostTypeId="2" ParentId="12967" CreationDate="2015-03-01T20:21:01.467" Score="13" Body="&lt;p&gt;There would be a great deal of variability on what happens depending on the airline, whether or not it was unionized, what country it was in, who the pilot was, and the specific situation of the flight involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scenario of an hour or less is a truly rare occurrence. The system is set up to prevent such happenings. The last two carriers I worked for had a 2-hour showtime. If a pilot hadn't checked in or been picked up by that time, the search immediately started for a replacement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only occurrence of an approximate one hour replacement need that I'm personally aware of was when a captain failed a breathalyzer test at his 2-hour show time. Given the confusion of the moment, it was well less than 2 hours when they started the search for a replacement. There was no ready reserve, and no management pilots available that were current, so they had to start stealing captains from flights due to depart later. I was due to operate JFK to AMS around 2 hours after the JFK to TLV flight they needed a captain for, so they stole me off my flight, which meant they had to get someone else for that, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is good reason for a 2-hour showtime other than just making sure a pilot is there. There is work to be done, and that work has to be done by someone. In this case, a non-current management pilot did that work, including my cockpit flow. I went directly into cockpit, sat down, and called for the before start checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was in this instance a good reason to do what could be done to avoid taking a delay. Numbers of flights leave JFK for Europe and the Middle East in the evening. If you take a delay, you may well get a lower altitude than planned because someone ahead of you has grabbed it; everybody's going over the North Atlantic track system. If that happens, you need more fuel, which is more cost, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would happen to a pilot causing a one-hour replacement depends on so many things I won't even try to address that other than to say that it could range from no penalty whatsoever to immediate termination. In the case above, the captain was terminated, and since he was in his late 50s back when the age 60 retirement rule was in effect, it was the end of his airline career insofar as U.S. airlines were concerned.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-03-01T22:38:35.343" LastActivityDate="2015-03-01T22:38:35.343" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12981" PostTypeId="1" AcceptedAnswerId="14777" CreationDate="2015-03-01T22:56:06.320" Score="15" ViewCount="3039" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Meredith_effect&quot;&gt;Meredith Effect&lt;/a&gt; was used on some aircraft to provide more thrust by channeling air through the radiator such that the air is expanded, heated and then compressed through a constriction, generating thrust.  How much thrust could such an installment generate?  How much net thrust, after accounting for drag, does such an installation generate?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="1696" LastEditDate="2015-03-02T17:46:07.943" LastActivityDate="2015-05-16T22:56:33.273" Title="How much thrust was provided by a typical Meredith Effect radiator?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12982" PostTypeId="1" AcceptedAnswerId="12984" CreationDate="2015-03-02T07:15:35.360" Score="23" ViewCount="20038" Body="&lt;p&gt;On a few international flights with non-full cabin, the crew has asked no one to move to open seats until the plane has finished take-off. I assumed this was just to force people to sit down during take-off and not cause problems, but when I asked I was told it was because of weight. The claim is, the airplane is balanced by where people are sitting. The next claim is by the end of the flight, there is less fuel, so if people have switched seats there is less of a problem. This weight balance apparently uses all information, people, baggage, and fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believed this, until recently a plane had lost at least 30 peoples baggage, some people had more than 1 bag. The bags were left at the previous airport, and on arrival no one knew that the bags were not on the plane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the lack of knowledge for bags not being on the plane (which seems logical, why would they depart without the bags), how did this change in weight not show in the take-off, or was this a dangerous occurrence?&lt;/p&gt;&#xA;" OwnerUserId="7476" LastEditorUserId="1696" LastEditDate="2015-03-02T20:08:39.007" LastActivityDate="2015-03-03T02:29:03.273" Title="Does weight and balance of an airplane matter more on takeoff?" Tags="&lt;commercial-aviation&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12983" PostTypeId="2" ParentId="12982" CreationDate="2015-03-02T08:00:18.630" Score="7" Body="&lt;p&gt;Regarding the core of your first question, takeoff is a sensitive &quot;critical phase of flight&quot; where center of gravity can affect the aircraft's ability to rotate. Generally takeoff has the tightest margin of safety, as you are at your heaviest. This affects your ability to rotate, as well as your ability to stop safely should there be a malfunction on takeoff.  The movement of people will affect the aircraft's ability to climb out safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want an extreme example of how center of gravity is important, &lt;a href=&quot;https://www.youtube.com/watch?v=-MB9JDBe4wA&quot; rel=&quot;noreferrer&quot;&gt;watch this video&lt;/a&gt;:  - the cargo broke loose and fell aft on takeoff causing the aircraft to pitch up out of control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For landing, it's generally just important that your center of gravity be within a certain window, which is larger after you've spent all of the fuel over the course of the flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the bags, that could have happened for several different reasons. Generally speaking though, the lack of bags would probably move the CG forward, which will probably make the flight safer (again, depending on the circumstances).&lt;/p&gt;&#xA;" OwnerUserId="302" LastEditorUserId="65" LastEditDate="2015-03-02T14:36:47.087" LastActivityDate="2015-03-02T14:36:47.087" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12984" PostTypeId="2" ParentId="12982" CreationDate="2015-03-02T08:40:02.960" Score="34" Body="&lt;p&gt;By regulation, a &quot;weight &amp;amp; balance&quot; must be computed before departure to ensure that the weight is within the weight limits for a number of different conditions and that the weight is distributed such that the c.g. (center of gravity) of the airplane is also within the longitudinal c.g. limits for those conditions. That c.g. is typically computed assuming the the passengers are in the seats they have been assigned. If the passengers are seated elsewhere, the computed c.g. is not accurate. In other words, the pilots wouldn't know where the c.g. is or whether it is even within limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The takeoff trim setting is affected by the c.g. If the pilots set the trim according to the computed value, and the c.g. is considerably aft of that, on liftoff the nose is going to want to pitch up more than the pilots expect. If the c.g. is so far aft that it is well beyond the aft limits, serious control problems can occur. If the c.g. is far forward of what the pilots are expecting, they're going to have to pull harder on the elevator control than expected to get the aircraft to rotate, and that is going to extend the takeoff roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different makes of aircraft vary widely in c.g. limitations and how tolerant they are limit wise of passenger placement in aircraft that are not full. For example, when I was flying Metroliners, if you had few passengers, you had to ask them to sit toward the rear. I once got a strange look from Rosey Grier (Google him if you don't know who he is) when I had to ask him to sit in the back of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you're in the air, the movement of passengers is of lesser concern balance wise. You're at speed, the elevator is fully effective, and the pilots or the autopilot keep the airplane in trim. In other words, the trim is what it is rather than a computed value that might not reflect reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, on large aircraft, once you're in the air in level flight and if you're so inclined, you can work out your weight by using your fuel flow, pressure altitude, and airspeed. Then with the weight and your trim setting you can come up with your c.g. I would guess that most of the glass cockpit aircraft probably do that for you automatically if you request it. My experience stopped with the 747-200, which is now a near relic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The c.g. limits are defined conservatively, and usually in terms of the percent of the mean aerodynamic chord. It's not a case of that if the aft c.g. limit is 33% mac (a common value for 747s) and you're at 33.1% you're going to crash. It's just a case that you're beginning to move into an area that gives you a lesser degree of controllability than is deemed necessary for some situations. Continued movement to an extreme value would eventually make the aircraft uncontrollable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insofar as the bags-left-behind part of the question, I don't think their absence would cause a problem. If the computed c.g. including the bags was right right up against the aft c.g. limit, their absence could conceivably put the c.g. beyond the aft limit. The pilots might notice it, but handling it would not be difficult. However, aircraft are typically not loaded such that their c.g. is close to a limit. A preferred aiming point for 747-100s, -200s, and -400s is 26.6% mac.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just for the heck of it, I did a weight &amp;amp; balance for a 747-400, loading it so that the takeoff c.g. was 26.6% mac. I then took 5000 lbs (100 bags x 50 lbs each) out of the most forward baggage area. This changed the the c.g. to 28.0% mac, still within limits. On the 747, a given weight of baggage misplacement has less potential to affect the c.g. than the same weight of passenger misplacement because the passenger seating extends over 20 feet forward of the most forward baggage compartment and over 17 feet aft of the most aft baggage compartment.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-03-03T02:29:03.273" LastActivityDate="2015-03-03T02:29:03.273" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="12985" PostTypeId="2" ParentId="12977" CreationDate="2015-03-02T10:01:11.580" Score="5" Body="&lt;p&gt;GE used the core of the F101 engine as the core of the CFM56 (with some modifications, presumably). The core of a turbofan consists of the high pressure compressor, the combustion chamber and the high pressure turbine. In this case, we talk about a 9-stage HPC and a single-stage HPT. Everything else was newly developed for the high-bypass turbofan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike just putting a larger fan on the low-pressure shaft, this is possible becasue the high-pressure components and the low-pressure components are relatively independent in a turbofan, i.e. the core of the engine is not affected too much by the size of the fan, the bypass ratio or other changes in the low-pressure area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new low pressure turbine (4-stage instead of 2-stage) can operate at a lower rpm and transmit more of the exhaust gas energy from the engine core to the larger fan (the exhaust gas coming out of the new LPT is probably cooler and slower than that coming out of the F101 LPT). The new low-pressure compressor increases the overall pressure ratio and therefore increases the amount of energy that goes to the low pressure compressor and fan, thereby improving the overall efficiency. This is probably possible because the non-supersonic operational envelope of the CFM56 means that intake air total temperatures will be much lower so that the same EGT margin can be achieved with a higher pressure ratio. In other words, becasue the incoming air is cooler, it can be compressed further without damaging the high-pressure turbine because it is too hot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The static thrust of the CFM56 is 19500 lbf, which is up about 15 % from the F101's 17000 lbf without the afterburner. While a small part of this is probably an aerodynamic loss due to the unused afterburner chamber, most of it has to come from the better use of the energy offered by the engine core exhaust in the larger fan. The difference might even be higher becasue the maximum thrust of the F101 might be adjusted for a much lower mean time between shop visits. I'm not sure about that though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shows that the main benefit of the high-bypass low pressure section of the engine is a significantly increased fuel efficiency, an increase in the static thrust and (much) lower noise levels. The F101, on the other hand, can operate at higher speeds, produce more thrust at high speeds, is lighter and has a much smaller cross-section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Edited per comment by fooot, thanks for finding the source.)&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="5665" LastEditDate="2015-03-08T09:17:11.993" LastActivityDate="2015-03-08T09:17:11.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12986" PostTypeId="1" AcceptedAnswerId="12987" CreationDate="2015-03-02T10:10:56.363" Score="7" ViewCount="2496" Body="&lt;p&gt;According to &lt;a href=&quot;https://ca.news.yahoo.com/blogs/good-news/passenger-helps-land-737-pilot-suffers-heart-attack-211136285.html&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; article, the pilot suffered a heart attack mid-air and a passenger helped in landing the plane safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does commercial airlines prepare themselves for these kind of situations. Do they specifically check if there are any pilots in the passenger manifest and inform the crew and pilots beforehand? Or, do they leave it to the co-pilot to take care of such situations? Or do they fly in a pilot (like mid-air refuel)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On digging deeper I found that pilot sickness has caused several crashes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nj.com/news/index.ssf/2009/07/transcript_of_flight_3407_cras.html&quot; rel=&quot;noreferrer&quot;&gt;Continental Flight 3407 co-pilot felt ill before crash near Buffalo, transcript shows&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://globalnews.ca/news/1764431/plane-damaged-pilot-felt-sick-fatal-transwest-air-crash-report/&quot; rel=&quot;noreferrer&quot;&gt;Plane damaged, pilot felt sick: fatal Transwest Air crash report&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.winnipegfreepress.com/canada/report-into-fatal-plane-crash-in-nwt-shows-plane-was-damaged-pilot-felt-ill-287950401.html&quot; rel=&quot;noreferrer&quot;&gt;Report into fatal plane crash in NWT shows plane was damaged, pilot felt sick&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="7532" LastEditDate="2015-12-15T20:53:18.433" LastActivityDate="2015-12-16T23:14:35.917" Title="How do commercial airlines prepare for pilots falling sick during the flight?" Tags="&lt;pilots&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="12987" PostTypeId="2" ParentId="12986" CreationDate="2015-03-02T10:18:48.270" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;do they fly in a pilot (like mid-air refuel)?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, that isn't really feasible!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/8950/1289&quot;&gt;Can a passenger jet be towed to safety if it breaks down in midair?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;do they leave it to the co-pilot to take care of such situations?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes. In both normal and emergency situations, the co-pilot is able to fly the aircraft, navigate to a nearby airport and land the aircraft without the assistance of the senior pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.skybrary.aero/index.php/In-flight_Pilot_Incapacitation_(OGHFA_SE)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skybrary&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Here are some lines of defense: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;The remaining pilot must assume or maintain control&lt;/strong&gt; &lt;/li&gt;&#xA;  &lt;li&gt;Establish a safe flight profile and engage the autopilot; use all possible automation &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Obtain cabin crew assistance&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Inform ATC &lt;/li&gt;&#xA;  &lt;li&gt;If on an extended-range twin-engine operations (ETOPS)&#xA;  flight, the remaining pilot or PIC must assess whether to continue&#xA;  the flight, return to the departure airport or divert. The decision&#xA;  is based on: &#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Weather conditions at the destination or alternate&lt;/li&gt;&#xA;  &lt;li&gt;Reduction of flight time if diverting &lt;/li&gt;&#xA;  &lt;li&gt;Workload involved in single-pilot operation &lt;/li&gt;&#xA;  &lt;li&gt;Familiarity with the alternate &lt;/li&gt;&#xA;  &lt;li&gt;Condition of the incapacitated pilot &lt;/li&gt;&#xA;  &lt;li&gt;Availability of medical assistance &lt;/li&gt;&#xA;  &lt;li&gt;Overall safety of the flight &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Arrange medical assistance upon arrival &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Brief a cabin crew member to assist if required&lt;/strong&gt; &lt;/li&gt;&#xA;  &lt;li&gt;Complete the approach and landing using the autopilot as much as possible &lt;/li&gt;&#xA;  &lt;li&gt;A partially incapacitated pilot should not be allowed to participate in the    subsequent operation of the aircraft, as&#xA;  judgment may be impaired&lt;/li&gt;&#xA;  &lt;li&gt;After landing, seek immediate medical assistance&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://www.ifalpa.org/store/14POS06%20-%20In-flight%20incapacitation%20-%20Flight%20crew%20training.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IFALPA - Pilot Incapacitation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The remaining pilot must first assume command and maintain control of the aircraft&lt;/strong&gt;. Furthermore the position of essential controls&#xA;  and switches should be checked, and in nearly all cases, use of the autopilot should be made and an emergency be declared.&#xA;  Use of the autopilot and priority of air traffic service are two obvious and effective ways of maintaining a tolerable level of workload.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The second step is to take care of the incapacitated flight crew member. The grounds for this are not entirely humanitarian; if left unattended an incapacitated pilot can become a major problem and in any case is a major distraction to the remaining crew. Thus&#xA;  the incapacitated pilot must be moved out of the range of flight controls. In all cases, the advisability of removing a pilot (perhaps unconscious) from the seat must be dictated by consideration of the phase of the flight, the crew available, and the contours of the&#xA;  flight deck.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Note: Consideration of the restraint and care of an incapacitated pilot dictates that cabin attendants are at least familiar with the&#xA;  operation of harness and seat controls&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Finally, and after the incapacitated flight crew member has been taken care of, &lt;strong&gt;the remaining flight crew should re-organise the cockpit work&lt;/strong&gt; and prepare for landing. Details will depend on many variables including such considerations as the type of aircraft being flown, phase of flight, en route and terminal weather, and many others.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How does commercial airlines prepare themselves for these kind of situations.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I imagine that it involves the usual measures&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;make pilots take regular medical tests.&lt;/li&gt;&#xA;&lt;li&gt;make pilots responsible for reporting own or crew illness, fatigue etc.&lt;/li&gt;&#xA;&lt;li&gt;prevent pilots eating the same meals in-flight.&lt;/li&gt;&#xA;&lt;li&gt;write procedures for pilot incapacitation in-flight.&lt;/li&gt;&#xA;&lt;li&gt;train flight crew to perform those procedures&lt;/li&gt;&#xA;&lt;li&gt;review and revise the above based on experience of relevant events.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From what I've read, non-pilot flight-crew are often given very basic training so that they understand the basics of flight. For example &lt;a href=&quot;http://www.tc.gc.ca/publications/en/tp12296/pdf/hr/tp12296e.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Transport Canada&lt;/a&gt; requires flight attendants initial training to include a pilot-incapacitation drill, an understanding of aircraft parts including rudder, ailerons etc, principles of flight, etc etc.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Do they specifically check if there are any pilots in the passenger manifest&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I believe the airline staff would often be aware of any airline pilots onboard (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Deadheading_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;dead-heading crew&lt;/a&gt;) but not of GA or military pilots flying as normal passengers.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-03-02T14:37:52.360" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12988" PostTypeId="1" AcceptedAnswerId="12990" CreationDate="2015-03-02T14:57:33.500" Score="9" ViewCount="3638" Body="&lt;p&gt;What are the highest aerodynamic pressures encountered in any aircraft? And does this limit the maximum speed of any aircraft at certain altitudes? Broadly, 'how fast can you go [at a given altitude]?'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where dynamic pressure $q$ is: $$q = \frac{1}{2} \rho v^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\rho$ is local air density, and $v$ is true airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly concerned with high performance fighters/bombers. Here's some data I've culled (Mk-12A and 787 added for reference):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;#   | Airframe      | Mach       | Speed     | Altitude    | q (kgf/m^2)&#xA;----|---------------|------------|-----------|-------------|------------&#xA;1.  | Mk-12A        | Mach  6.15 | 2,100 m/s |       0 ft  | 273,000&#xA;2.  | Mk-12A        | Mach 22.6  | 6,900 m/s | 100,000 ft  |  39,300&#xA;3.  | X-51A         | Mach  5.1  | 1,500 m/s |  64,000 ft  |  11,100&#xA;4.  | HTV-2         | Mach 20.   | 5,812 m/s | 125,000 ft? |  10,700&#xA;5.  | F-111         | Mach  1.2  |   410 m/s |       0 ft  |  10,400&#xA;6.  | B-1A          | Mach  1.2  |   410 m/s |       0 ft  |  10,400&#xA;7.  | B-1B          | Mach  0.9  |   310 m/s |       0 ft  |   6,100&#xA;8.  | X-43A         | Mach  9.6  | 3,000 m/s | 109,000 ft  |   4,800&#xA;9.  | Skylon        | Mach  5.5  | 1,630 m/s |  85,300 ft  |   4,600&#xA;10. | SR-72         | Mach  6    | 1,800 m/s |  90,000 ft? |   4,400&#xA;11. | Space Shuttle | Mach  1.3? |   400 m/s |  35,000 ft  |   3,200?&#xA;12. | XB-70         | Mach  3.0  |   880 m/s |  73,000 ft  |   2,500&#xA;13. | SR-71         | Mach  3.2  |   930 m/s |  78,740 ft  |   2,300&#xA;14. | Concorde      | Mach  2.0  |   600 m/s |  60,000 ft  |   2,100&#xA;15. | Boeing 787    | Mach   .85 |   250 m/s |  35,000 ft  |   1,200&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Airframes #3, #4, and #5/6 are quite different from each other, so I'm surprised they share roughly the same max $Q$. Is 11,000 kgf/m^2 a common limit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: All figures are for level flight except for the Mk-12A (reentry), Space Shuttle (ascent), and HTV-2 (glide).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;[Mk-12A]:&lt;/strong&gt; Current reentry vehicle for the Minuteman III ICBM, houses the W78 warhead (350 kT). Figures are for reentry.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;[HTV-2]:&lt;/strong&gt; Rocket glider. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;[B-1B]:&lt;/strong&gt; &quot;[top speed] is limited by the need to avoid damage to its structure and air intakes,&quot; according to Wikipedia. The B-1B used less structural Titanium and a simpler fixed geometry inlet when the speed requirement was lowered from the B-1A. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;[Skylon]:&lt;/strong&gt; Obviously doesn't exist yet. Reaction Engines' &quot;user manual&quot; for the Skylon discusses the flight profile.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;[SR-72]:&lt;/strong&gt; Obviously doesn't exist yet. Lockheed Martin discussed Mach 6 cruise. 90,000 ft cruising altitude is just my placeholder value.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;[Space Shuttle]:&lt;/strong&gt; Figures for ascent.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Some background and purpose:&lt;/strong&gt; For fun, I'm trying to design a hypersonic long-range heavy bomber. I was curious what would limit the maximum low/mid-altitude speed: drag (available engine thrust), max $Q$ (structural strength), or skin temperature (thermal protection system)... but I'll get to that in another question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read through nearly all the aerodynamic, military, aircraft design, aircraft performance, and jet engine tags, looking for answers. (Really, this is a marvelous community.) Finally realized I could ask my own question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've tried to follow the etiquette as best as I can, but I'm pretty new to Stack Exchange, so let me know if I should change anything :) Thanks!&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2015-03-02T17:30:12.110" LastActivityDate="2018-04-08T10:14:28.030" Title="Which aircraft endure the highest Max Q's (aerodynamic pressure)?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;military&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12989" PostTypeId="2" ParentId="12977" CreationDate="2015-03-02T15:39:49.753" Score="4" Body="&lt;p&gt;Fitting a larger fan does two things to the thrust of an engine:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The static thrust is increased. Static thrust is the thrust produced when the engine is not moving.&lt;/li&gt;&#xA;&lt;li&gt;The thrust gradient over speed becomes more negative, which means that thrust will decline more with speed when the bypass ratio is increased.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But there is more: Exit speeds at the nozzle are reduced, and a bigger intake is required, since the bigger fan will need more air. Increasing the bypass ratio means taking some of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;kinetic energy of the core flow&lt;/a&gt; and turning this into a higher fan mass flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at the formula for the propulsive efficiency $\eta_p$ of an airbreathing engine:&#xA;$$\eta_p = \frac{v_{\infty}}{v_{\infty} + \frac{\Delta v}{2}}$$ where $v_{\infty}$ is the speed of the engine and $\Delta v$ the speed increase of the gas flowing through the engine, the speed dependency becomes clear: When $v_{\infty}$ is low, a smaller $\Delta v$ acting on a higher mass flow makes the engine more efficient. When $v_{\infty}$ is high, however, this effect disappears, and now the smaller engine with a smaller and lighter intake becomes more attractive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the core of the engine stays the same, its fuel consumption will also stay the same, but the bigger fan will create more thrust, especially at low speed. The core mass flow will be the same, regardless of fan size, and the amount of &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983#4983&quot;&gt;fuel to heat this mass flow&lt;/a&gt; will also not change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since efficiency is defined as thrust per unit of fuel consumed, the bigger fan will also increase efficiency.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-02T15:51:58.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12990" PostTypeId="2" ParentId="12988" CreationDate="2015-03-02T16:21:35.377" Score="8" Body="&lt;p&gt;First, your example list doesn't distinguish between stationary and instationary trajectories. A reentry vehicle will see the highest dynamic pressure only momentarily at the end of its trip, and aerodynamic heating can be tolerated either by ablative cooling or a decently sized heat sink. All it has to sustain is the dynamic pressure at the tip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first samples on your list which need to continuously sustain the given dynamic pressure are the low-altitude attack aircraft B-1B and F-111. Here the dynamic pressure is given by wing loading, aerodynamics and raw thrust to keep the aircraft moving at its maximum speed. Aerodynamic heating comes on top at high altitude, because the stagnation point heat is independent of air density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons to limit the maximum dynamic pressure are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;gust loads at low altitude. Hitting the same updraft at higher speed will proportionally increase the load factor.&lt;/li&gt;&#xA;&lt;li&gt;Aeroelastic deformation: Higher dynamic pressure means also higher torsional and bending loads, and the deformed structure might become unstable when the deformation increases the loads which lead to this deformation. Flying at higher dynamic pressure requires a stiffer and heavier structure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you look at the flight envelope of the SR-71 (below), it should be obvious that at each altitude only a narrow band of speed was available due to the high wing loading (= high minimum dynamic pressure) and the maximum dynamic pressure (at low altitude) rsp. the aerodynamic heating (at high altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pI67e.gif&quot; alt=&quot;SR-71 flight envelope&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SR-71 flight envelope (picture &lt;a href=&quot;https://www.sr-71.org/blackbird/manual/5/5-9.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-06-23T21:34:10.843" LastActivityDate="2017-06-23T21:34:10.843" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="12991" PostTypeId="1" AcceptedAnswerId="12992" CreationDate="2015-03-02T18:21:14.190" Score="3" ViewCount="2758" Body="&lt;p&gt;This official image from the &lt;a href=&quot;https://www.google.co.za/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CCMQFjAB&amp;amp;url=http%3A%2F%2Fwww.airbus.com%2Ffileadmin%2Fmedia_gallery%2Ffiles%2Ftech_data%2FAC%2FAirbus-AC_A319_May2014.pdf&amp;amp;ei=4qf0VI-sG-i07gapjID4Dw&amp;amp;usg=AFQjCNHTyVszlUGopKiWytyjfwcTos2xIg&amp;amp;sig2=gXx2TdRSuPXQIY70ptupWQ&amp;amp;bvm=bv.87269000,d.ZGU&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft characteristics airport and maintenance planning&lt;/a&gt; document for the A319 advertises the A319 as accommodating 156 passengers in a high density layout, this is also the figure in other Airbus documentation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/m05je.png&quot; alt=&quot;A319 cabin arrangement, 156 seats&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I would like to know is how emergency exists is accommodated for? In the image it shows a row of seats at the exits, but I was under the impression that there is not allowed to be seats in line with the emergency exits? Can this variant thus only accommodate 150 passengers (156 - 2*3)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is also valid for the A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then I would also like to know, is there a policy for the amount of lavatories on board the aircraft, or is that simply a choice made by the airline? Are there for example airlines that have only one or even none lavatories on board models only used for short hauls? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you for any help.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="1696" LastEditDate="2015-03-02T19:51:00.500" LastActivityDate="2015-03-02T20:03:15.150" Title="How can the Airbus A319 accommodate 156 passengers with overwing emergency exits?" Tags="&lt;airliner&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="12992" PostTypeId="2" ParentId="12991" CreationDate="2015-03-02T18:57:49.393" Score="5" Body="&lt;p&gt;Yes, airlines can use a 156 seat layout in the A319. &lt;a href=&quot;http://www.seatguru.com/airlines/Allegiant_Air/Allegiant_Air_Airbus_A319.php&quot; rel=&quot;nofollow&quot;&gt;See Allegiant's layout&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA type certification for the A320 series can be found on the site &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, under TCDS A28NM. For the A319:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Maximum Passengers:&lt;br&gt;&#xA;  145&lt;br&gt;&#xA;  See note 11 and 18&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  Note 11:&lt;br&gt;&#xA;  If modification 32208 is embodied in production on A319 airplanes, the aircraft is eligible for maximum capacity of 160 passengers. This modification consists in structural and system provision for the installation of second pair of overwing emergency exits.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The certification basis section g states that the design complies with the following regulations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;25.811(e)(3) Type III emergency exit marking.&lt;/li&gt;&#xA;&lt;li&gt;25.813(c) for emergency exit access&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The regulation from section &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.25#se14.1.25_1813&quot; rel=&quot;nofollow&quot;&gt;25.813&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§25.813   Emergency exit access.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The following must be provided for each Type III or Type IV exit—(1) There must be access from the nearest aisle to each exit. In addition, for each Type III exit in an airplane that has a passenger seating configuration of 60 or more—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;(i) Except as provided in paragraph (c)(1)(ii), the access must be provided by an unobstructed passageway that is at least 10 inches in width for interior arrangements in which the adjacent seat rows on the exit side of the aisle contain no more than two seats, or &lt;strong&gt;20 inches in width&lt;/strong&gt; for interior arrangements in which those rows contain three seats.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The A320 series has three seats on each side, so the applicable distance is a 20 inch wide passage. The referenced paragraph (c)(1)(ii) is also interesting:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(ii) In lieu of one 10- or 20-inch passageway, there may be two passageways, between seat rows only, that must be at least 6 inches in width and lead to an unobstructed space adjacent to each exit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This appears to be one layout that &lt;a href=&quot;http://www.seatguru.com/airlines/Air_Canada/Air_Canada_Rouge_A319_new.php&quot; rel=&quot;nofollow&quot;&gt;Air Canada uses&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://toilet-guru.com/aircraft.php&quot; rel=&quot;nofollow&quot;&gt;There doesn't appear to be any regulation&lt;/a&gt; requiring a certain number of lavatories. Aircraft sometimes fly &lt;a href=&quot;http://articles.latimes.com/2014/jan/13/travel/la-tr-spot-20140112&quot; rel=&quot;nofollow&quot;&gt;with only one working&lt;/a&gt;. Evidently &lt;a href=&quot;http://consumerist.com/2007/08/10/there-is-no-law-or-regulation-that-says-airplanes-have-to-have-working-toilets/&quot; rel=&quot;nofollow&quot;&gt;no US agency requires even at least one&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the DOT does appear to have a rule created by the Air Carrier Access Act &lt;a href=&quot;http://airconsumer.ost.dot.gov/publications/disabled.htm&quot; rel=&quot;nofollow&quot;&gt;that says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;New twin-aisle aircraft must have accessible lavatories.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I read that as requiring the aircraft to have at least one, possibly two, lavatories, and that they must be accessible.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;New aircraft&quot; requirements apply to U.S. airlines with respect to planes ordered after April 5, 1990 or delivered after April 5, 1992. In general they apply to foreign carriers with respect to aircraft ordered after May 13, 2009 or delivered after May 13, 2010.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course this wouldn't apply to the A320 series, as it is a single-aisle design. Although some twin-aisle aircraft do operate on shorter routes, they are probably less likely to go the route of &quot;&gt;200 people, no toilets.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-03-02T20:03:15.150" LastActivityDate="2015-03-02T20:03:15.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12993" PostTypeId="1" AcceptedAnswerId="12995" CreationDate="2015-03-02T19:21:35.540" Score="5" ViewCount="1049" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/FedEx_Express_Flight_14&quot; rel=&quot;noreferrer&quot;&gt;[Source:]&lt;/a&gt; The aircraft had departed with one &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_reverser&quot; rel=&quot;noreferrer&quot;&gt;thrust reverser&lt;/a&gt; (on the left wing) inoperative, and the pilots knew of incidents in the craft's maintenance log where the auto-brakes had failed to activate during landings. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why not fix and then recheck the defective parts? Were these pilots deliquent and remiss?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Footnote: I learned of  this flight accident first after watching &lt;a href=&quot;http://en.wikipedia.org/wiki/FedEx_Express_Flight_80&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Mayday&lt;/em&gt;, Season 14, Episode 5.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="128" LastActivityDate="2015-03-02T20:27:08.413" Title="Is it negligent to depart with one thrust reverser inoperative?" Tags="&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="12994" PostTypeId="2" ParentId="12982" CreationDate="2015-03-02T19:33:29.733" Score="-2" Body="&lt;p&gt;The airplane must have enough power and &quot;lift&quot; so that it can clear any obstacles at the end of the runway.   The more weight at takeoff, the more lift is required.   The &quot;lift&quot; of an aircraft is dependent on temperature, barometric pressure, and humidity.  These things affect the density of the air.  And, the lower air density produces less lift, so the total weight of the aircraft must be reduced to insure a safe takeoff.&lt;/p&gt;&#xA;" OwnerUserId="7484" LastActivityDate="2015-03-02T19:33:29.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12995" PostTypeId="2" ParentId="12993" CreationDate="2015-03-02T19:37:32.953" Score="10" Body="&lt;p&gt;No, it is not negligent.  Landing performance data assumes no thrust reverser usage and thrust reversers can be dispatched inoperative per the Minimum Equipment List (MEL) with a logbook entry and possibly the inoperative reverser mechanically locked/disabled.  With a single thrust reverse operative, depending on the aircraft and airline ops, the other one may or may not be used.  If it is used, caution in maintaining directional control during landing is advised.  Any such stipulations will be part of the MEL verbiage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A proper MEL action will consist of a logbook entry by the pilots or maintenance, a logbook sign-off by maintenance and dispatch notification of the MEL.  Thus, the pilots, maintenance and dispatch are all aware of the issue.  Lastly, and special requirements of the MEL will be noted by the crew when they consult the MEL book after noticing the MEL in the logbook and in the dispatch paperwork.   In the airplane I am familiar with you could visually note the thrust reverser locking bolt during the walk-around inspection to verify that maintenance had done its job properly.  This also presented a nice opportunity to query the First Officer and see how well they were paying attention during the inspection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The situation would only be negligent if proper procedures were ignored.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="2171" LastEditDate="2015-03-02T20:27:08.413" LastActivityDate="2015-03-02T20:27:08.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="12996" PostTypeId="1" CreationDate="2015-03-02T23:51:02.787" Score="8" ViewCount="3963" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737#Variants&quot;&gt;The longest version is almost 50% longer than the shortest&lt;/a&gt;, and even within the &quot;next generation&quot; models, the difference is almost 40%.  Why such a big difference in lengths?&lt;/p&gt;&#xA;" OwnerUserId="7486" LastEditorUserId="1696" LastEditDate="2015-03-03T00:19:07.110" LastActivityDate="2015-03-03T16:45:39.600" Title="Why does the length of the 737 vary so much?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="12997" PostTypeId="1" AcceptedAnswerId="13006" CreationDate="2015-03-03T01:19:27.743" Score="46" ViewCount="10195" Body="&lt;p&gt;I've flown on a few commercial flights, and on several of them I recall a phase of the flight during descent when the engine seemed to go idle (or at least, the engine noise subsided substantially) and then all of the sudden, the engine got really loud and I could feel the plane slowing down substantially, as in, I felt the same as if I was in a car that was slowing down suddenly.  This seemed to last between 5 and 15 seconds, or possibly slightly longer, and then the engines got more quiet and the noticeable deceleration stopped. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Living under an incoming flight path for a few years I have also noticed many times that a plane will be going overhead by the fact that suddenly the engine will get few loud for about the same amount of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to be rather common, and I always assume this was reverse thrust.  But today I am reading two separate questions: &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9577/is-it-possible-to-use-reverse-thrust-while-airborne?rq=1&quot;&gt;Is it possible to use reverse thrust while airborne?&lt;/a&gt;&quot; and &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2007/why-cant-most-jets-safely-use-reverse-thrust-while-airborne?rq=1&quot;&gt;Why can't most jets safely use reverse thrust while airborne?&lt;/a&gt;&quot;, the answers to both of which seem to imply that using reverse thrust while airborne is very rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what have I experienced / heard?  I'm pretty sure it's not an airbrake, because far as I can tell a speed brake is a more passive device that doesn't involve the engine, and it would seem to defeat its purpose to spool up the engine while using it.  I've never been in a seat where I could actually see the back of an engine to tell if a reverser was deployed, but I think at least in some cases the speed brakes were also deployed; from in front of the wing this made it impossible to see the back of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: Everyone is saying speed brakes... how long are these usually deployed for? &lt;/p&gt;&#xA;" OwnerUserId="3695" LastEditorUserId="13197" LastEditDate="2018-12-20T22:59:02.320" LastActivityDate="2018-12-21T16:04:15.883" Title="If airplanes can't use reverse thrust in flight, what am I hearing?" Tags="&lt;approach&gt;&lt;thrust-reverser&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="12998" PostTypeId="2" ParentId="12997" CreationDate="2015-03-03T01:49:17.280" Score="13" Body="&lt;p&gt;The noise you are most likely hearing from inside the cabin is the speed brakes (also known as spoilers). In addition to drag, they create a lot of turbulence, which creates a lot of noise. After looking at some videos, it doesn't seem to come through on video as well. There does seem to be more noise at lower frequencies though. The &lt;a href=&quot;https://books.google.com/books?id=HgELBgAAQBAJ&amp;amp;lpg=SA15-PA14&amp;amp;ots=GNcFvrx-Zp&amp;amp;pg=SA15-PA14#v=onepage&quot;&gt;FAA Airplane Flying Handbook&lt;/a&gt; notes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There is usually a certain amount of noise and buffeting associated with the use of speed brakes...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When outside the aircraft, you may be hearing the engines spool up. During approach and landing, the pilots are extending flaps and landing gear. This and the maneuvering can cause the autothrottle to spool up the engines to compensate for added drag, or the pilots may be manually adjusting the throttle, to maintain or reach a certain speed. Speed brakes are generally used when the airplane is higher and faster on approach, and when heard from the ground, the plane is more likely to be lower and slower, using throttle to adjust speed.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-03-03T03:19:43.030" LastActivityDate="2015-03-03T03:19:43.030" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="12999" PostTypeId="2" ParentId="12996" CreationDate="2015-03-03T01:58:16.387" Score="13" Body="&lt;p&gt;Airlines want to have different sizes of aircraft to match their passenger loads as well as possible. The different loads may be for different routes, times, or airlines. It is more efficient to fly a smaller plane if extra space isn't needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft manufacturers have some options for how to meet this demand. They can create a whole new airplane for each size, but this is expensive for everyone involved. Each plane would have to be certified separately, requiring much more time and testing. They may not be alike, requiring pilots to be trained on each individual one. And airlines would have to maintain all the different types of airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, aircraft manufacturers choose to stretch the fuselage to fit in more passengers. This can allow most other things on the plane to remain the same, with generally just minor modifications. This greatly decreases the amount of design and testing required to create the new size of aircraft. The same pilots and mechanics can work on any of the sizes, since most parts and features are common to all of them. There will be some inefficiency, in that parts on the small versions are designed to withstand higher loads of the bigger versions, but this is more than offset in the cost savings of having common parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft come in different versions with different lengths, but it can be most noticeable on the smaller planes like the 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturers also market their products based on their coverage of different seat capacity. Each manufacturer is able to cover a wide range of seat capacity by offering different sizes of 3 basic models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ApDCY.jpg&quot; alt=&quot;Airbus and Boeing aircraft capacity chart&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://leehamnews.com/2013/06/14/airbus-v-boeing-on-wide-bodies/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-03-03T16:45:39.600" LastActivityDate="2015-03-03T16:45:39.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13000" PostTypeId="1" CreationDate="2015-03-03T03:08:23.650" Score="9" ViewCount="2304" Body="&lt;p&gt;While cumbersome, is it permissible when asking for a pop-up IFR clearance to state, &lt;code&gt;at the intersection of WWW radial XXX and YYY radial ZZZ?&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, during VMC, you have your pick of visual checkpoints, but in IMC, are there any better suggestions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, if you are near a navaid or published intersection, and take a guess at your distance from it, how far off would your guess have to be before ATC wouldn't really even consider it helpful?&lt;/p&gt;&#xA;" OwnerUserId="7488" LastEditorUserId="65" LastEditDate="2015-03-03T16:16:20.823" LastActivityDate="2021-02-10T01:45:19.150" Title="What is the best way to give ATC a position report using only a VOR (no DME or GPS)?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;&lt;instrument-procedures&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13001" PostTypeId="2" ParentId="12997" CreationDate="2015-03-03T03:46:41.347" Score="5" Body="&lt;p&gt;My guess would be that you're feeling accelerations more upwards rather than to the rear. It is common when flying a plane to need to adjust descent rate for various parts of the approach, either because different phases of the approach actually need different descent rates or to correct your glide path. When you need to decrease your rate of descent (or even level out) for a part of the approach, you do that by temporarily adding engine power. This will also usually be accompanied by pitching up a bit. I'm guessing that the forces you're feeling are the descent rate slowing down rather than the actual forward speed slowing down (though you might be doing some of that, too, if they pitch up enough.) I've experienced this commonly on commercial flights during approaches. We also make use of the engine to slow a descent/correct a glide path when flying light aircraft. Once the desired descent rate has been achieved, engine power will be reduced again, so this results in the few-to-several-second-long bursts of engine power that you're describing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As fooot mentioned, when the gear and flaps are dropped, engine power is also added to compensate for the increased drag in order to maintain airspeed. However, this is not generally just a brief burst of power as in the above case of needing to arrest a descent rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have mentioned, there is some noise when spoilers (speed brakes) are being used to quickly slow down the aircraft in flight, but, at least in my experience, this sounds nothing even remotely like the engines spooling up. I would certainly not expect that you'd hear this from the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is, however, rather certain that you are &lt;em&gt;not&lt;/em&gt; feeling thrust reversers. As far as I know, these are &lt;em&gt;never&lt;/em&gt; intentionally deployed in flight on current commercial airliners (as UFO mentions, the DC-8 was actually certified for that, but I doubt you hear many DC-8s flying over these days.) There have been a few cases where malfunctions have caused them to deploy in flight, but I don't remember hearing about any cases of them being intentionally deployed in flight on current-model airliners.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-03-03T04:07:44.393" LastActivityDate="2015-03-03T04:07:44.393" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13002" PostTypeId="2" ParentId="13000" CreationDate="2015-03-03T07:51:59.060" Score="7" Body="&lt;p&gt;I'm going on the assumption you're operating in IMC (or perhaps VMC above a cloud deck) and have no reference to the ground. In a situation if you need a pop-up IFR clearance or ATC is requiring you to provide position reports for some other reason (non-radar, or your transponder is dead and they want to identify you but don't have time to issue you confidence maneuvers).&lt;br&gt;&#xA;I'm going to further constrain the scenario with the assumption that all you have are &quot;basic&quot; IFR instruments (6-pack, clock, compass, and VOR -- no VFR/Handheld GPS, DME, or other fancy stuff).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/AIM/aim0503.html#aim0503.html.3&quot; rel=&quot;nofollow&quot;&gt;The AIM has some guidance on this subject in 5-3-2&lt;/a&gt;, but the general idea is your report should be &quot;as accurate as possible&quot;. For routine position reporting like you'd use in non-radar environments (where you're giving an estimate of when you'll reach a reporting point) they're looking for &quot;within 2 minutes flying time&quot; on your estimates in most situations, so you'll want to give your position with the same sort of accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case you describe, with no DME, GPS, or other precision tool for reporting your distance and bearing from a fix your the most accurate option would be to report crossing a published intersection, VOR, or other reporting point noted on your chart - it's the most definite &quot;I am &lt;em&gt;HERE&lt;/em&gt;&quot; report you can give, and ATC will certainly know the location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that's not an option (ATC needs to know where you are &lt;em&gt;right now&lt;/em&gt;, and you're not over a VOR or charted intersection) I would probably start by computing the distance using the intersection of two VOR radials (whether this is a charted intersection doesn't matter, though it would help if your &lt;em&gt;report&lt;/em&gt; is relative to one): Break out your chart and mark the location, then take your ruler and measure the distance from one of the stations (or a nearby intersection along the airway you're using) and you've got your position &quot;as accurately as possible&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't have a chart or can't get signal from a second VOR for some reason it's time to work out a time/speed/distance problem in the air:&lt;br&gt;&#xA;If you flew over ABC VOR 10 minutes ago and are now flying &lt;em&gt;from&lt;/em&gt; the VOR on the 090 radial at 120 knots, and you've got a 20 knot headwind (which you know from the Winds Aloft forecast, updated with data from previous position and time/speed/distance computations) then you know you've traveled about 17 miles, so you're &quot;17 miles from ABC VOR, on the 090 radial&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time/speed/distance computation has a lot of potential error (winds not as forecast, for one), but sometimes it's your only option.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-03-05T07:16:50.950" LastActivityDate="2015-03-05T07:16:50.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13003" PostTypeId="1" AcceptedAnswerId="13004" CreationDate="2015-03-03T09:07:46.330" Score="12" ViewCount="4680" Body="&lt;p&gt;This is a continuation from &lt;a href=&quot;https://aviation.stackexchange.com/questions/12952/what-does-it-mean-for-a-door-to-be-armed&quot;&gt;this question&lt;/a&gt;, whereby it discussed the meaning and significance of an armed door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, is it possible to open an armed door from outside, for example, if for some reason the passenger or crew are incapacitated, due to inhalation of poisonous gasses etc.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-12-07T19:07:33.333" Title="Can an armed door be opened from outside an airliner?" Tags="&lt;aircraft-design&gt;&lt;emergency&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13004" PostTypeId="2" ParentId="13003" CreationDate="2015-03-03T09:21:37.980" Score="17" Body="&lt;p&gt;&lt;em&gt;This depends on the aircraft:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;DC9, MD80, B727, B737&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On some (especially older model) aircraft doors such as the Boeing 737 for instance this is directly dangerous, since the slide is attached on the inside by hand with the means of a &lt;em&gt;girt bar&lt;/em&gt; to the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is hence no way to open the door without the slide going off should it be armed. There is a helpful notice in red on the outside to &quot;stand clear&quot; when the red banner is crosses the window, the indication that it is armed. Judging by the space required and force the doors have, this is still most probably very dangerous idea that should not be used unless absolutely necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aRcP1.jpg&quot; alt=&quot;![http://upload.wikimedia.org/wikipedia/commons/4/4f/Aircraft_Door_B737_or_A320_family.JPG](door)&quot;&gt;&#xA;&lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Aircraft_Door_B737_or_A320_family.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airbus, B757, B767, B777, MD11, E-Jets&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On more modern aircraft, this is safe: opening the door externally will push the arm handle to the disarmed position before proceeding to open it. This is for instance the case on all Airbus aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/a26-IkTjn88?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=a26-IkTjn88&quot; rel=&quot;nofollow noreferrer&quot;&gt;This video&lt;/a&gt; provides a nice example.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2017-01-28T21:22:31.973" LastActivityDate="2017-01-28T21:22:31.973" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13006" PostTypeId="2" ParentId="12997" CreationDate="2015-03-03T10:59:28.870" Score="75" Body="&lt;p&gt;It is normal for engines to spool up during the approach. The initial part of the approach, from cruise level down to approximately 10 miles from the airport, is flown at flight idle power. This is the most efficient way to get down. In the final part of the approach, flaps and landing gear add so much drag that the engines need to be well above idle power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low speeds required for landing, the wing of the aircraft will not produce enough lift to sustain flight. To compensate for the low speed, flaps are extended. They do not only increase the lift, they also increase the drag. When the flaps are extended, suddenly the drag increases, resulting in a deceleration. Extending the landing gear has a similar effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally the flight crew will limit the time that they fly at low speed and high drag. The first couple of degrees of flaps deployment are relatively efficient;they do not add a lot of drag but allow the aircraft to fly slower. When the aircraft is about 7 to 10 nautical miles from the runway, the crew will transition the aircraft to landing configuration for the final approach. Often there is a horizontal segment before the aircraft starts a 3 degree glide path down to the runway. The crew will ensure that enough flaps (drag) is added before they start this final segment, otherwise they have difficulty reducing speed (they usually try to prevent use of speed brakes in that part of the flight). &#xA;Often there is a sequence of flap and gear extension before the final descent segment starts. This causes the aircraft to decelerate from the efficient high speed configuration (flaps 2 or less on the B737) to the landing configuration. At the end of that configuration sequence the aircraft has a lot of drag and is decelerating rapidly towards the final approach speed. To stop the deceleration extra power is commanded which spools up the engines and stops the deceleration. To reduce the spool up time of the engines, the engine control system (FADEC) will give a short burst of power. This what you hear while still decelerating. When the engines are spooled up they start to produce thrust which is the end of your deceleration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=5OcXqH1E0Jw&amp;amp;t=28m20s&quot; rel=&quot;noreferrer&quot;&gt;youtube video&lt;/a&gt; shows how it happens. When at 28:20, the aircraft (Boeing 737) is flying horizontally, flaps 2, and is about to start decelerating and descending for landing. Keep a look at the thrust levers(right bottom corner of the screen) and the airspeed (on the left of the artificial horizon). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It begins at 28:28 when the captain ask for flaps 5, and reduces the thrust in order to reduce to final approach speed. 15 seconds later he asks for gear down and flaps 15. The speed is now reducing rapidly. Starting at 28:50 the thrust levers are moved forward, until they are reduced again at 29:08. This is the power boost you hear. In 40 seconds the aircraft is transformed from low drag / low thrust to landing configuration. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2018-12-21T16:04:15.883" LastActivityDate="2018-12-21T16:04:15.883" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="13007" PostTypeId="2" ParentId="12997" CreationDate="2015-03-03T12:52:29.770" Score="2" Body="&lt;p&gt;Quite not possible because of the nature of reverse thrust (may not be as directional and controllable as required.)&#xA;  Can't say of future developments, but as of now, spoilers are the maximum possible &quot;Airborne Braking&quot; that can be deployed. &lt;/p&gt;&#xA;" OwnerUserId="4111" LastActivityDate="2015-03-03T12:52:29.770" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13008" PostTypeId="2" ParentId="12979" CreationDate="2015-03-03T13:35:50.720" Score="18" Body="&lt;p&gt;I'm not sure the history provided in the Wikipedia article is entirely accurate, for the fact that &lt;em&gt;both&lt;/em&gt; engines in an outward spinning, two-prop counter-rotating configuration are &lt;a href=&quot;http://en.wikipedia.org/wiki/Critical_engine&quot; rel=&quot;noreferrer&quot;&gt;critical&lt;/a&gt;.  This is confirmed in the introduction of &lt;a href=&quot;http://www.scribd.com/doc/53068385/F-82-Twin-Mustang&quot; rel=&quot;noreferrer&quot;&gt;this book&lt;/a&gt;, though it seems to be written well after the fact and without reference to the oft-quoted story of not getting enough lift on its maiden run:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Turning the propellers toward the fuselage meant much better control during single-engine operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Likewise, the &lt;a href=&quot;http://books.google.com/books?id=UggPCtYPyQ8C&amp;amp;printsec=frontcover&amp;amp;redir_esc=y#v=onepage&amp;amp;q=Single-engine%20control%20characteristics&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;republished F-82 Operator's Manual&lt;/a&gt; boasts, &quot;Single-engine control characteristics of this airplane are exceptionally good.&quot;  Again (but also as expected), no mention of any trial and error in the design phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the more I researched the F-82's design, I found various and unsourced information.  Many sites repeated the initial flight test story, while another said the first attempt's failure was &lt;a href=&quot;http://www.militaryfactory.com/aircraft/detail-page-2.asp?aircraft_id=182&quot; rel=&quot;noreferrer&quot;&gt;attributed to weight&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is that initial designs of the F-82 simply borrowed from the slightly earlier P-38's final configuration, where the outward-spinning counter-rotating propellers &lt;a href=&quot;http://www.ww2aircraft.net/forum/technical/propellers-38-lightning-rotate-outwards-10566.html#post294441&quot; rel=&quot;noreferrer&quot;&gt;reduced downwash&lt;/a&gt; on the horizontal stabilizer and made for a &lt;a href=&quot;http://www.fighter-planes.com/info/p38_lightning.htm&quot; rel=&quot;noreferrer&quot;&gt;more stable gunnery platform&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for figuring out the lift cancellation in the F-82's center wing section, it is probably helpful to explain first what effect a single propeller has on the wing behind it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, a spinning propeller creates a downstream vortex in the same direction as the propeller is rotating.  The area of wing behind the upswing of a propeller blade experiences a higher angle of attack to the resultant airflow, resulting in increased lift and drag across that section of the wing.&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ZDi5o.jpg&quot; alt=&quot;propeller slipstream&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image source: &lt;a href=&quot;http://www.caa.govt.nz/fig/basic-concepts/effects-of-controls.html&quot; rel=&quot;noreferrer&quot;&gt;Civil Aviation Authority of New Zealand&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise, the opposite occurs on the downswing side, resulting in a net increase in lift and net decrease in drag behind the engine as a whole.  This single-engine airflow model is generally true for multiple-engine models with &lt;a href=&quot;http://www.researchgate.net/profile/Benoit_Marinus/publication/260622595_Influence_of_OEI-conditions_for_a_Down_Between_Engines_configuration_of_a_propeller_equipped_aircraft/links/0a85e531da9ad3cf68000000.pdf&quot; rel=&quot;noreferrer&quot;&gt;all propellers spinning in the same direction&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The interaction of the slipstream with the wing produces an increase in overall lift coefficient. This net increase is the result of a local increase in local lift coefficient $C_L$ for the part of the wing located in the slipstream with up-rotation while the downrotation induces a local decrease in $C_L$. The local drag coefficient $C_d$ is locally increased in the uprotation part and decreased over the down-rotation section.  The net result is generally a reduction of drag on the wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the F-82 seems to be an enigma in this regard.  Theoretically, an outward rotation should have &lt;em&gt;increased&lt;/em&gt; lift on the center section, not reduced it.  So why didn't it?  Perhaps there was &lt;strong&gt;&lt;em&gt;too much interaction&lt;/em&gt;&lt;/strong&gt; between the two propeller wakes.  Again, consider the P-38 Lightning.  Though they both have twin counter-rotating engines and two tail booms connected by a shared horizontal stabilizer, the P-38 has a big center fuselage for the pilot sitting right between the two engines, effectively isolating the individual propeller slipstreams.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.researchgate.net/profile/Benoit_Marinus/publication/260622595_Influence_of_OEI-conditions_for_a_Down_Between_Engines_configuration_of_a_propeller_equipped_aircraft/links/0a85e531da9ad3cf68000000.pdf&quot; rel=&quot;noreferrer&quot;&gt;study&lt;/a&gt; on the &quot;Down Between Engines&quot; (DBE) configuration of the Airbus A400M noted &quot;[strong] interact[ion]&quot; of its counter-rotating engines' slipstreams&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;especially [in] the part of the wing located between both engines and results in a local decrease in lift coefficient that is &lt;strong&gt;not entirely offset by the local increase on those parts of the wings that experience upward motion&lt;/strong&gt; &lt;em&gt;(emphasis mine)&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;resulting in both decreased lift and increased drag in the wing section between the engines.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that DBE (i.e. inward-spinning propellers) was the fix for the F-82's lift woes; that the inter-engine wing region &lt;em&gt;still&lt;/em&gt; experiences decreased lift and increased drag in the more preferable counter-rotating configuration underscores the notion that interaction of propeller slipstreams is not desirable.  My guess is that this switch removed &lt;em&gt;just enough&lt;/em&gt; of the adverse lift conditions so as to enable the aircraft to get airborne.  It would be interesting to find out if anyone modified an F-82 to remove the counter-rotating aspect.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;UPDATE:&#xA;At long last, I have found what appears to be the most credible source for the Wikipedia article, a &lt;a href=&quot;http://xp-82twinmustangproject.blogspot.com/p/articles-news.html&quot; rel=&quot;noreferrer&quot;&gt;2013 issue of Warbirds magazine&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The first flight was (at least somewhat) attributed to being overweight.  A second attempt on 16 June 1945 &lt;a href=&quot;http://3.bp.blogspot.com/-k2kbtOv3YXM/UTepRpyqw7I/AAAAAAAAB9E/lcm2rfLfR4k/s1600/Page+5.jpg&quot; rel=&quot;noreferrer&quot;&gt;went unexpectedly airborne&lt;/a&gt; for over an hour after taking off with a limited fuel load.&lt;/li&gt;&#xA;&lt;li&gt;The interaction between the propellers created an &lt;a href=&quot;http://3.bp.blogspot.com/-k2kbtOv3YXM/UTepRpyqw7I/AAAAAAAAB9E/lcm2rfLfR4k/s1600/Page+5.jpg&quot; rel=&quot;noreferrer&quot;&gt;early stall condition&lt;/a&gt; forward of the wing when combined with the normal upward flow, causing the lift over the center wing to &lt;a href=&quot;http://1.bp.blogspot.com/-6hOZpJN2X2k/UTepAEkmyMI/AAAAAAAAB80/9gPhWQKcosI/s1600/Page+6.jpeg&quot; rel=&quot;noreferrer&quot;&gt;predictably suffer&lt;/a&gt;.  According to NAA aerodynamicist Ed Horkey:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;What was happening was that we had propellers rotating in different directions on the left and right engines.  For some reason, which I can't remember, we started with the blades moving upward in front of the center section.  What this does, particularly at high angles of attack, is to create upward flow approaching the leading edge of the center section of the wing.  You also have normal upflow ahead of the wing.  The two upflows would add together to create an early stall.  The center section represented a large portion of the wing's area.  What was happening was that we were stalling out early and just not getting enough lift. ... We changed the rotations to go down the middle and we had the problem solved.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-12T14:01:26.883" LastActivityDate="2015-03-12T14:01:26.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13009" PostTypeId="2" ParentId="13000" CreationDate="2015-03-03T14:36:04.760" Score="3" Body="&lt;p&gt;Press the NRST button on your GPS, and give them the distance/direction from the fix:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;5-4-XRay is 7 miles southeast of K-A-S-H&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just because you are /U, it doesn't mean you can't use a VFR or handheld GPS for non-navigational position reporting. If you're IFR and don't yet, in 2015, have a an IFR or VFR GPS, or a handheld GPS running an aviation app in the cockpit, you should turn in your ticket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RDggD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-03-03T14:50:40.800" LastActivityDate="2015-03-03T14:50:40.800" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13011" PostTypeId="1" AcceptedAnswerId="13012" CreationDate="2015-03-03T17:19:54.767" Score="25" ViewCount="5536" Body="&lt;p&gt;We have several questions here about what happens to an aircraft when it gets struck by lightning (e.g. &lt;a href=&quot;https://aviation.stackexchange.com/q/888/65&quot;&gt;this question&lt;/a&gt;), and at least one answer from a former pilot who knows he was struck once and thinks he was struck other times. &lt;strong&gt;How frequently do aircraft get struck by lightning?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional commentary on &lt;em&gt;how do you know you've been struck&lt;/em&gt; would be appreciated, but I'll make that a separate question if it's more appropriate.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-31T21:24:54.273" Title="How frequently do aircraft get struck by lightning?" Tags="&lt;weather&gt;&lt;lightning&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13012" PostTypeId="2" ParentId="13011" CreationDate="2015-03-03T17:47:20.133" Score="13" Body="&lt;p&gt;Lightning strikes airplanes &lt;a href=&quot;http://www.scientificamerican.com/article/what-happens-when-lightni/&quot;&gt;commonly&lt;/a&gt;, and for modern airplanes, it is not a big deal. Although, to put a definite number is not realistic, as it is not analogues to how many miles a car runs with a full tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On average, &lt;a href=&quot;http://flightsafety.org/aerosafety-world-magazine/june-2010/when-lightning-strikes&quot;&gt;it is estimated&lt;/a&gt; that lightning strikes an airplane &lt;strong&gt;once every 1000 hours of flight time&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot;&gt;as mentioned&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The frequency of lightning strikes that an airplane experiences is&#xA;  affected by several factors, including the geographic area where the&#xA;  airplane operates and how often the airplane passes through takeoff&#xA;  and landing altitudes, which is where lightning activity is most&#xA;  prevalent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="43" LastEditDate="2015-03-03T21:24:41.590" LastActivityDate="2015-03-03T21:24:41.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13013" PostTypeId="2" ParentId="13011" CreationDate="2015-03-03T17:50:04.980" Score="21" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;It is estimated that on average, each airplane in the U.S. commercial fleet is struck lightly by lightning more than once each year.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edward J. Rupke, via &lt;a href=&quot;http://www.scientificamerican.com/article/what-happens-when-lightni/&quot;&gt;Scientific American&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Federal Aviation Administration estimates that on average, lightning hits each airliner in U.S. service once a year.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2014/08/27/why-is-an-airplane-safe-from-lighting-strikes/&quot;&gt;Washington Post&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like commercial airliners get struck about once a year. I was also able to find an &lt;a href=&quot;http://www.faa.gov/aircraft/air_cert/design_approvals/transport/Cert_Update/Edition21-30/media/Edition23.pdf&quot;&gt;FAA source&lt;/a&gt;, but it doesn't look like it's the original source.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2015-03-03T17:50:04.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13014" PostTypeId="2" ParentId="13000" CreationDate="2015-03-03T19:49:17.040" Score="-2" Body="&lt;p&gt;You don't say whether you talking about center or a tower. I would definitely never give a tower such a position. If I was talking to an ATCSCC, maybe in wierd scenario (broken transponder for example), but in all honesty it is the pilot's job to have charts and report position properly. Trying to get a controller to pull out a chart and compute your position is not a good idea, and I doubt they would cooperate unless it was an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In real life, what happens when you don't know your position, is that you would have the controller find you with radar, so you just say &quot;Boston Center, Cessna November 54321&quot;, and center will answer &quot;Go ahead November 54321&quot;, then you say &quot;November 54321, what is my position?&quot; and control will say &quot;Ident&quot;, then you push a button on your radar transponder. This causes a &quot;blossom&quot; on the controller's radar screen and he can see exactly where you are. The controller will then give your position to you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this often happens even when you accurately report your position. So, for example, you might call in &quot;Nashua Tower, Cessna one seven two November five four three two one, six miles west of water tower, maintaining three thousand five hundred, with information Romeo&quot;, then tower might say, &quot;November five four three two one, ident&quot;, then you push the button. Then, they will know exactly where you are.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-03T19:58:11.970" LastActivityDate="2015-03-03T19:58:11.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13015" PostTypeId="1" AcceptedAnswerId="13016" CreationDate="2015-03-03T20:05:46.923" Score="26" ViewCount="9823" Body="&lt;p&gt;Landing on a carrier seems like a difficult and risky task for military pilots, especially at night when the carrier should keep low profile and is practically unlit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems exactly like a problem which can better be performed by a computer rather than a human being. A machine can take in account exactly the motion of the carrier and other parameters and land the aircraft precisely where it should. The fact that there should be no enemy aircraft nearby also means that the initiative of a pilot is not needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system can:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Either be exclusively inside the aircraft (doing image recognition of a carrier and trying to determine where to land; not sure how easy and reliable this can get),&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Or be presented as a subsystem within the carrier which sends the encrypted information to the authenticated aircraft about the exact position of given points of the carrier and a second subsystem inside the aircraft which relies on this information to make the controlled landing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why isn't it handled (yet) by a computer? Are there projects of implementing such system?&lt;/p&gt;&#xA;" OwnerUserId="2773" LastEditorUserId="4067" LastEditDate="2015-03-05T14:02:13.683" LastActivityDate="2017-05-21T14:59:07.180" Title="Why is landing on a carrier not handled by a computer?" Tags="&lt;landing&gt;&lt;software&gt;&lt;aircraft-carrier&gt;" AnswerCount="8" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13016" PostTypeId="2" ParentId="13015" CreationDate="2015-03-03T20:24:14.267" Score="32" Body="&lt;p&gt;&lt;a href=&quot;https://books.google.com/books?id=nV0Osu4FMu0C&amp;amp;lpg=PA144&amp;amp;ots=NyB63fnzF3&amp;amp;pg=PA144#v=onepage&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Navy does have systems&lt;/a&gt; that are capable of &lt;a href=&quot;http://www.navair.navy.mil/index.cfm?fuseaction=home.displayPlatform&amp;amp;key=E8D18768-14B6-4CF5-BAB5-12B009070CFC&quot; rel=&quot;nofollow noreferrer&quot;&gt;guiding an airplane in for a landing&lt;/a&gt;, and some aircraft can use this system to &lt;a href=&quot;http://en.wikipedia.org/wiki/Modern_United_States_Navy_carrier_air_operations&quot; rel=&quot;nofollow noreferrer&quot;&gt;land completely on the autopilot&lt;/a&gt;. However, &lt;a href=&quot;http://www.gao.gov/products/NSIAD-86-214BR&quot; rel=&quot;nofollow noreferrer&quot;&gt;the system has not always been reliable&lt;/a&gt; and still has its limits, and other reasons for not always using this system are &lt;a href=&quot;https://aviation.stackexchange.com/questions/910/why-dont-pilots-always-use-autoland&quot;&gt;similar to those for land-based aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further reasons for this technology not being more fully developed yet are probably similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1802/why-do-we-still-use-pilots-to-fly-airplanes&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A completely automated, unmanned landing on a carrier has been done, &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_X-47B&quot; rel=&quot;nofollow noreferrer&quot;&gt;but only fairly recently&lt;/a&gt;. Although a computerized system is theoretically more capable of performing precise carrier landings, the details are complex. A lot of sensing and control must be worked out. The team behind the X-47B was awarded the &lt;a href=&quot;http://en.wikipedia.org/wiki/Collier_Trophy&quot; rel=&quot;nofollow noreferrer&quot;&gt;Collier Trophy&lt;/a&gt; for the advances in aeronautics they achieved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sensors and processing that the UAV uses to do this are probably not all standard equipment on naval aircraft. Adding them would create extra expense and weight. If the system requires addition to the carrier as well, there is more added expense. And in a combat situation, do you want to rely on systems that could be jammed or failed? If you are going to land the plane without a pilot, you might as well not have the pilot at all, and this is the route that future unmanned systems are taking, but there is a lot more work to be done before they completely replace human pilots.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-04T15:34:34.773" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13017" PostTypeId="2" ParentId="643" CreationDate="2015-03-03T20:24:18.187" Score="0" Body="&lt;p&gt;The first spots where ice accretion occurs are sharp angles and spikes.  This makes the external thermometers and pitot tubes the first locations where icing occurs.  Ice doesn't normally accrete where the static ports are located unless you have a huge icing problem.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-03-03T20:24:18.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13018" PostTypeId="2" ParentId="13015" CreationDate="2015-03-03T20:37:42.677" Score="-2" Body="&lt;p&gt;Computers are excellent at solving problems that are predictable and repeatable. Landing on an aircraft carrier is exactly the opposite of that. Computers can land very accurately on a static runway, but a runway that is moving and bouncing around on waves is an entirely different story, especially when you don't have the goal of broadcasting your position to the world. Keep in mind that we don't even have good self-driving cars, yet. Google probably has the most advanced ones and those are currently capped at 25 mph. Fighters on approach will be doing 6-10 times that speed and moving in three dimensions while attempting an approach to something else that is also moving (somewhat unpredictably) in three dimensions and at speeds likely as fast Google's cars. It's not as easy as it might sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it wouldn't surprise me if systems like this are in the works (it would surprise me more if they were not,) it's unlikely that any such development work would be unclassified. Very few programs designed to add advanced capabilities to military systems are unclassified.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-03-03T21:12:54.137" LastActivityDate="2015-03-03T21:12:54.137" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13019" PostTypeId="2" ParentId="643" CreationDate="2015-03-03T21:09:44.270" Score="1" Body="&lt;p&gt;To perhaps be a bit more clear on the &quot;why&quot; question, the opening of pitot tubes must face into the windstream. By contrast, the opening of the static ports should be perpendicular to the wind stream. Since the water that causes ice accretion is generally moving with the air, it will be constantly hitting the pitot tube opening, but not hitting the static port opening (or not nearly as much, at least.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not by coincidence that pitot tubes are generally in locations where ice will accrete while static ports usually aren't. It is instead a necessary consequence of each of them meeting their design goals.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-03-03T21:09:44.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13020" PostTypeId="1" CreationDate="2015-03-03T21:30:33.140" Score="2" ViewCount="2433" Body="&lt;p&gt;I can't find the notice of disapproval that I was given after I failed the oral portion of my private pilot checkride. I have looked EVERYWHERE.  What do I need to do?  Is there something on IACRA or can I go back to the examiner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am fairly close to taking the checkride again (I switched instructors), and I am under the impression that I need to take that paper with me. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any suggestions?&lt;/p&gt;&#xA;" OwnerUserId="7496" LastEditorUserId="62" LastEditDate="2015-03-03T21:33:57.523" LastActivityDate="2015-03-03T22:15:06.307" Title="Where can I get a copy of my notice of disapproval from a failed checkride?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;checkride&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13021" PostTypeId="2" ParentId="13015" CreationDate="2015-03-03T21:54:33.130" Score="33" Body="&lt;p&gt;Computers can, in fact, control the approach of a Super Hornet all the way to touchdown.  However, there are limits to the sea state. Gross deviations in glide path resulting from a pitching deck would make a coupled approach impractical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the most compelling reason to hand fly all our approaches is that we fly a $60 million jet. Murphy's Law tells us that the most junior guy, with the least experience behind the boat, is going to get an engine fire, at night, in rough seas.  If our fictional JO wasn't proficient hand flying the ball behind the boat this could result in catastrophic consequences including both the loss of aircrew and aircraft. As often as possible, we prepare for the 1 percentile, not the 99th percentile, so when we do get that engine fire at night we get the upgrade &lt;em&gt;OK&lt;/em&gt;, and not the cut pass/ ejection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plus, its just plain eerie letting the jet fly itself to the boat, and the current system isn't reliable enough that most guys would feel comfortable letting it fly itself on a regular basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:  Heck, new guys aren't even allowed to perform auto approaches (auto throttle) to the boat for the same reason.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="65" LastEditDate="2015-03-04T16:28:46.733" LastActivityDate="2015-03-04T16:28:46.733" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13022" PostTypeId="2" ParentId="13020" CreationDate="2015-03-03T22:00:23.683" Score="8" Body="&lt;p&gt;As far as I'm aware you can't pull the &quot;completed&quot; application from IACRA (with the examiner's notice of disapproval &amp;amp; failed areas on it). Much like with your knowledge test report you need to hang on to that original bit of paper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't believe you &lt;em&gt;NEED&lt;/em&gt; to bring the Notice Of Disapproval with you to a retest though.&lt;br&gt;&#xA;61.43 says, in part:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;f) If a practical test is discontinued, the applicant is entitled credit for those areas of operation that were passed, but only if the applicant:&lt;br&gt;&#xA;  (1) Passes the remainder of the practical test within the 60-day period after the date the practical test was discontinued;&lt;br&gt;&#xA;  (2) Presents to the examiner for the retest the original notice of disapproval form or the letter of discontinuance form, as appropriate;&lt;br&gt;&#xA;  (3) Satisfactorily accomplishes any additional training needed and obtains the appropriate instructor endorsements, if additional training is required; and&lt;br&gt;&#xA;  (4) Presents to the examiner for the retest a properly completed and signed application.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you only &lt;em&gt;need&lt;/em&gt; it if you want to skip over the parts of the test you passed. If you don't have it, or your retest is more than 60 days after your original failed checkride, the examiner will have to give you a full exam, with no credit for the stuff you already completed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Given that you failed the oral there's probably not much &quot;credit for those areas of operation that were passed&quot; you can claim, so it probably doesn't matter much that you lost the original notice of disapproval. You're almost certainly getting a &quot;full checkride&quot; anyway.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-03-03T22:15:06.307" LastActivityDate="2015-03-03T22:15:06.307" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13023" PostTypeId="2" ParentId="13015" CreationDate="2015-03-03T22:18:42.707" Score="-4" Body="&lt;p&gt;There are three main reasons: reaction time, sensor inadequacy, and predictive intelligence. Taking them in order...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For certain types of stimulus-response activities a human can respond faster and has a better &lt;strong&gt;reaction time&lt;/strong&gt; than a computer. For example, imagine it takes 50 milliseconds to sense something completely, 100 milliseconds to transmit that information to the computer, and 100 milliseconds for the computer to figure out the right action, and 80 milliseconds to transmit the response to an actuator. That's a total of 330 milliseconds. A human can respond to an event in 200 milliseconds. Note that for some types of actions the computer's sense-and-respond loop could be much slower than the numbers I have given. For example, most artificial intelligence algorithms are complicated and take a lot longer than 100 milliseconds to complete. Some types of optimization algorithms, like dynamic programming have unpredictable running time, so they might finish in say 50 milliseconds with one set of inputs and 1000 milliseconds in another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next big problem is that the human eye, which is wired in parallel directly to the brain, is a far better &lt;strong&gt;sensor&lt;/strong&gt; than anything available to an aircraft. It has a wider field of view, higher bandwidth and better focusing and movement ability than any man-made optical system. Currently the sensors on planes are things like inertial measurement units, GPS and flight instruments (altimeter etc). These sensors are not enough to reliably land a plane on flight deck except in very calm conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, landing on a moving flight deck requires &lt;strong&gt;predictive intelligence&lt;/strong&gt;. You basically have to guess where the deck is going to be in the future, combine that with estimated wind gusts, and then calculate in the future motion of the aircraft given a range of factors. Putting all this together is currently way beyond the ability of artificial intelligence systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are actually a lot of things MUCH simpler than landing on a flight deck that we cannot do. For example, if the Air Force could just land UAVs in heavy cross winds that would be a huge win for the military. Currently, if the cross wind component is above a certain amount we cannot even land UAVs because they would crash. This is because the UAV cannot react fast enough to a wind gust the way a real pilot can. We lose hundreds of millions of dollars in UAVs every year because of simple stuff like this, and remember these are manned system that are only semi-automated. Fully automated aircraft don't even exist, because they would crash so much as to be much more costly and dangerous than useful.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-03T22:38:45.843" LastActivityDate="2015-03-03T22:38:45.843" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="13024" PostTypeId="2" ParentId="13015" CreationDate="2015-03-03T23:06:56.660" Score="12" Body="&lt;p&gt;Reliability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the computer or the sensors it needs are damaged (in combat or otherwise) or malfunctioning then the human has to bring the plane in. The only way the human is going to be able to do that extremely precise flying is through regular disciplined practice. They can't practice if the computer is doing the landing for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until you can leave the human behind you may as well make use of them.&lt;/p&gt;&#xA;" OwnerUserId="7498" LastActivityDate="2015-03-03T23:06:56.660" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13025" PostTypeId="1" AcceptedAnswerId="13064" CreationDate="2015-03-03T23:55:44.670" Score="25" ViewCount="8070" Body="&lt;p&gt;I've recently been watching an interesting documentary on helicopter paramedic teams. As you all probably know, their job consists of a lot of sitting around doing nothing before a scramble and then a short (or not-so-short) flight out to the middle of nowhere and back again. On the (UK) documentaries I've seen, the aircraft are usually based at reasonably large commercial airports, physically located close to the fixed-wing runways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to find the guy lying injured in the field and help him out of asystole, they have to rapidly launch from a presumably busy airspace, and get there ten minutes ago. Do airports have procedures that allow them to always assume an &quot;exit route&quot; is always okay, under some ceiling? Do they have to get take off clearance as other private aircraft would? I understand that they get given &lt;a href=&quot;https://aviation.stackexchange.com/questions/3439/how-do-police-ambulance-helicopters-communicate-with-atc&quot;&gt;priority ATC clearance when in controlled airspace&lt;/a&gt;, but quite often their target call-to-takeoff times are less than two minutes, and it seems unlikely that the nearby 777 on FA would be done that quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens if it's not possible to be VFR entirely on route? I have seen cases reported where difficulties are encountered due to fading light halfway through treating a patient -- &#xA;meaning that the pilot is worried he can't take off again. It seems rather odd that, if a pilot was able to land in a field comfortably with good visibility, he can't ask for a route to be cleared, file a flight plan, and go to hospital IFR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For that matter, how do police helicopters chase the bad guys at night in zero visibility? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Disclaimer&lt;/em&gt;: I've never set foot in a helicopter in my life, but have a single-digit number of hours in light aircraft -- sick people are more my forte.&lt;/p&gt;&#xA;" OwnerUserId="7499" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2021-01-12T11:55:13.803" Title="Do emergency services helicopters fly VFR when leaving base?" Tags="&lt;air-traffic-control&gt;&lt;helicopter&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13026" PostTypeId="1" AcceptedAnswerId="13032" CreationDate="2015-03-03T23:57:57.450" Score="7" ViewCount="291" Body="&lt;p&gt;I am considering designing and building an automatic air-sampling unit that can be placed in the cabin of an airliner and left unattended for an extended period of time.  The device will use an electronic air sensor and (small) processor so that it can detect and sample fume events without crew intervention, will be battery powered using a small battery of a known-reliable type (i.e. not Lithium-Ion :), will not have any functions that intentionally emit RF, and will be packaged in an enclosure (either plastic with internal shielding or metal).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What EMC and electrical-safety requirements/specifications must this device meet in order to avoid posing a hazard to the aircraft it is placed on, and how do I ensure that this box is not mistakenly considered a security threat to the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="97" LastEditDate="2015-04-22T00:26:21.597" LastActivityDate="2015-04-22T00:26:21.597" Title="What safety requirements are there when designing an electronic device to go inside the cabin of an airliner?" Tags="&lt;avionics&gt;&lt;security&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13028" PostTypeId="2" ParentId="13026" CreationDate="2015-03-04T00:18:58.993" Score="9" Body="&lt;p&gt;A document called RTCA DO-160 defines the testing for a number of environmental requirements. Within each test standard is normally a number of different test conditions. The level of required testing is normally defined by the customer of the device, who has the task of showing the regulating body (FAA, EASA, etc) that this is sufficient to ensure the aircraft meets all regulatory requirements.&#xA;In addition, DO-254 gives guidance for electronic hardware and DO-178 handles software. There are other legacy documents like MIL-specs that define testing as well. &lt;/p&gt;&#xA;" OwnerUserId="7443" LastActivityDate="2015-03-04T00:18:58.993" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13029" PostTypeId="2" ParentId="13025" CreationDate="2015-03-04T01:59:39.040" Score="4" Body="&lt;p&gt;I don't fly rotocraft, but I can tell you if the airport is of any size they have to get a clearance unless they want to be turned into a hood ornament.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the helicopter is pre-flighted and ready to go, it only takes few seconds to get a clearance, so it will not normally cause a delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning IFR Flight: rotocraft require special equipment to fly IFR and it is much, much more dangerous than flying aircraft IFR because you are landing off field. Each operator and pilot have different policies, but in general police helicopters will rarely if ever fly IFR, and medivacs will only fly IFR if they judge it safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that flying at night is not the same thing as flying IFR. If the sky is clear it is VFR, even if it is night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being on a medivac crew is the most dangerous regular job in the United States and hundreds have died doing it.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-04T01:59:39.040" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13032" PostTypeId="2" ParentId="13026" CreationDate="2015-03-04T13:43:51.960" Score="8" Body="&lt;p&gt;I am assuming from your description this is not a permanent part of the aircraft and is just an instrument that will be brought on board. The DO-254's cited by Porcupine above are authorized under FAR 25.1309 which is only for permanent equipment that are an integral part of the aircraft design, not cargo items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, there are no FAA regulations about that kind of equipment, other than hazardous cargo materials (flammables, lithium batteries, etc). Even radios and RF emitters are ok, if the airline company and pilot agree to it. Flight crews sometimes bring their own personal radios on board as backups, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The policy about bringing something like this aboard would largely depend on the owner/operator and one might have completely different requirements or reaction than another. Your best bet would be to contact the operator (airline company) you want to work with and ask them what their requirements are.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-04T13:43:51.960" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13033" PostTypeId="2" ParentId="13015" CreationDate="2015-03-04T14:58:14.720" Score="3" Body="&lt;p&gt;There is, in fact, a current Navy project that is aimed at providing automated carrier landing capabilities to aircraft. An overview of this project can be found &lt;a href=&quot;http://www.dcmilitary.com/article/20141030/NEWS14/141039966/magic-carpet-meets-the-fleet&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.onr.navy.mil/Science-Technology/Directorates/office-innovation/~/media/Files/03I/News-Sept13-Vol10.ashx&quot; rel=&quot;nofollow&quot;&gt;on this PDF (page 24)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It goes by the humorously engineered acronym MAGIC CARPET, which stands for &lt;a href=&quot;http://www.aviationweek.com/defense/flight-control-advances-promise-big-savings&quot; rel=&quot;nofollow&quot;&gt;Maritime Augmented Guidance with Integrated Controls for Carrier Approach and Recovery Precision Enabling Technologies&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The goal is to utilize a combination of the flaps, via direct lift control, and the auto-throttle to maintain a constant glide slope.&lt;/p&gt;&#xA;" OwnerUserId="2231" LastEditorUserId="65" LastEditDate="2015-03-04T17:34:52.143" LastActivityDate="2015-03-04T17:34:52.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13035" PostTypeId="2" ParentId="13025" CreationDate="2015-03-04T15:41:00.807" Score="13" Body="&lt;p&gt;I dont fly rotorcraft but I do interact with emergency choppers in 2 ways. I'll speak form what I have seen, I am in Philadelphia (PA, USA) so all my experience is with the procedures around here (FAA).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Storage And Takeoff:&lt;/strong&gt;&lt;br&gt;&#xA;I am currently doing my training at Northeast Philadelphia Airport (KPNE) where the local police and news choppers are stored (I think the medical choppers are there as well but I have yet to see them there). I have seen them depart often and generally they can get in the air and get out of the way so fast they don't interrupt normal aircraft traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have, on a few occasions, been instructed to extend my downwind for one of them to land or take off but again they are out so fast it's almost a non-issue. Keep in mind that KPNE is not Philly international so I don't know what its like at other cities and if they hold traffic for them. I would think they try to store the choppers at smaller airports near the city for this reason. Most major cities have a few airports anyway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Landing At The Hospital:&lt;/strong&gt;&lt;br&gt;&#xA;My apartment happens to be next to one of the major hospitals in Philadelphia and I have the pleasure of looking right at the pad on the roof from my window. That being said I also have the &quot;pleasure&quot; of watching them practice and make approaches at the hospital. I can confirm that they have made landings (and frequently at that) in IFR conditions or even what seems below IFR minimums.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say in the time frame I am home (after 5pm every day) they make on average one landing every other day or more. If the weather is good, they will try and get more in, I would assume these are practice but I can't see the doors of the chopper so I can't be sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is in my area the rescue choppers do fly IFR. I'll try and capture a picture today (it's very cloudy) if they are on approach.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-24T13:10:43.830" LastActivityDate="2015-06-24T13:10:43.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13036" PostTypeId="2" ParentId="7813" CreationDate="2015-03-04T17:59:41.147" Score="0" Body="&lt;p&gt;Yes, you could certainly do this, especially for a smaller plane like a charter that was flying an unknown route. By this means you could temporarily divert the aircraft. Note several things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You would have to do it gradually; if you made a sudden change in position, the pilots would probably notice, so it would only work on a long flight&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It would not work if the pilots knew the route well. What would happen is that the trick would start to influence the heading and the pilot would see the unexpected heading and get confused (why are we on 040? shouldn't we be on 052 to Chicago?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The diverted heading would have to be roughly similar to the expected heading. For example, if the pilots know they are going north, and the diverted heading is south, they will immediately know something is wrong.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If it was a domestic commercial flight or at least had a flight plan with flight following activated, it would probably get noticed by ATC. For example, even a private pilot, if he has requested flight following will get notified by ATC if he starts to deviate significantly from the planned route. For this reason, a diversion would be most effective if it was an international flight or going through uncontrolled air space.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As far as the spoofing itself, it is easy as long as the person has enough expertise. Even a weak earth-bound transmitter will easily overpower real GPS signals. To create the spoofed signals the engineer can use a GPS simulator on the planned diverted route and record them. Then, they just play back the simulation record and transmit it. Note that this will only work if you know ahead of time the aircraft's planned route and speed. If you do not know ahead of time its original trajectory, you would have to observe its current flight path (by ACARS, radar or some other method), compute the diversion, simulate it and transmit it dynamically, which would be more complicated.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-04T18:06:03.120" LastActivityDate="2015-03-04T18:06:03.120" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13037" PostTypeId="1" AcceptedAnswerId="21592" CreationDate="2015-03-04T18:07:14.927" Score="22" ViewCount="48248" Body="&lt;p&gt;In my experience, almost every time the topic of air traffic control (as a career) comes up in conversation, someone makes a remark like&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air traffic control - isn't that a very stressful job?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Notwithstanding the fact that this point could be debated, surely there are many other &quot;stressful&quot; jobs which don't receive this kind of response.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is this: &lt;em&gt;How did the &quot;stressful&quot; air traffic control job become such a common perception?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2019-11-16T05:50:02.210" Title="Why is the air traffic control profession so commonly perceived as &quot;stressful&quot;?" Tags="&lt;air-traffic-control&gt;&lt;career&gt;" AnswerCount="8" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13038" PostTypeId="2" ParentId="13037" CreationDate="2015-03-04T18:20:00.810" Score="14" Body="&lt;p&gt;It is a common perception because it is a reality.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Listen to Live ATC tapes of the final approach to ORD.  These controllers are talking non-stop, making decisions and issuing instructions that very literally have hundreds of lives in the balance.  If they get it wrong, it is not just &quot;oops, let's try better next time&quot;.  It has to be right every time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now some - in fact many - ATC positions are far less busy and stressful.  So it all depends....&lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-03-04T18:20:00.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13039" PostTypeId="1" CreationDate="2015-03-04T18:23:28.740" Score="6" ViewCount="379" Body="&lt;p&gt;Related to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1007/will-occupants-usually-survive-a-decent-autorotation&quot;&gt;this question.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instructor described an auto-rotation as:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Entry.  Lever down, stick back, pedal in.&lt;/li&gt;&#xA;&lt;li&gt;Fly normally, with a little tweaking of RRPM to keep it in the green, until about 50 feet above the ground.&lt;/li&gt;&#xA;&lt;li&gt;Perform a quick stop.&lt;/li&gt;&#xA;&lt;li&gt;Perform an engine failure in the hover.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I can see the logic in this but, all of the autos that I have done have been far too busy to think about it like this and all the ones I've done to the ground have been run-ons so step 4 was not an option.  Without significant extra training and experience I would not even contemplate a zero-zero landing so in practice, I will probably never get to test the theory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this a valid way of thinking about the manoeuvre?  I'm not suggesting that anyone does anything other than what they were taught, just thinking about how these four manoeuvres roll into one.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2018-01-03T02:21:58.570" Title="Is this a reasonable way of thinking about an auto-rotation?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13040" PostTypeId="2" ParentId="13037" CreationDate="2015-03-04T19:56:28.740" Score="5" Body="&lt;p&gt;Not that it had that big of an effect but there was a movie made in the 90's (&lt;a href=&quot;http://en.wikipedia.org/wiki/Pushing_Tin&quot;&gt;Pushing Tin&lt;/a&gt;) about air traffic controllers and the stress the job brings. In typical Hollywood fashion there are some over dramatic moments, but its not a terrible movie if you like aviation. I would watch it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again I don't think it has a huge effect on how people view controllers but its worth bringing up.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-03-04T20:15:27.997" LastActivityDate="2015-03-04T20:15:27.997" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13041" PostTypeId="2" ParentId="2045" CreationDate="2015-03-04T20:20:30.923" Score="1" Body="&lt;p&gt;They do exist, almost every flight school has them but I have never heard of a free one. As is mentioned it will most likely run you in the range of $100 (that's how much mine was when I got started). They take you up for about 45 minutes of flying and let you maneuver the plane, generally basic stuff, show you what it's all about and then bring you back. I am a little confused  about your line:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I don't care if someone has to sit with me&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Planes are not like cars, they will not just let you take them out for a test flight willy nilly, especially if you don't have a PPL and most assuredly if you have never even flown before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A CFI will be right next to you for the first large chunk of your actual training. The other option is to ask around and see if you can find a family friend with a plane. Some times driving to small air fields and asking around may get you somewhere. I have never done it but it really depends where you live. Usually pilots are looking for people to fly with and you may get lucky and get a free ride but you wont find one from a flight school.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-03-04T21:46:31.623" LastActivityDate="2015-03-04T21:46:31.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13042" PostTypeId="1" AcceptedAnswerId="13048" CreationDate="2015-03-04T22:13:36.777" Score="69" ViewCount="115896" Body="&lt;p&gt;Could you run a jet with gasoline? Why do all jet engines use kerosene?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="487" LastEditDate="2015-03-05T20:53:52.773" LastActivityDate="2017-09-21T23:11:33.470" Title="Why do jet engines use kerosene rather than gasoline?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;" AnswerCount="6" CommentCount="16" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13043" PostTypeId="1" CreationDate="2015-03-04T22:16:23.893" Score="4" ViewCount="4948" Body="&lt;p&gt;More than once on the ramp, I've wished I could check an aeroplane's pitot-static system for leaks, but I didn't have the test box.  I've since seen, in the FAA's handbook for checking  homebuilts, a way of gently pressurizing a pitot system which is great - a length of medical tubing is all you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know if a similarly simply elegant arrangement exists for the static system?  I've tried a largish hypodermic syringe to check if the port was blocked, but the challenges are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;getting to sit tight on the static port, and &lt;/li&gt;&#xA;&lt;li&gt;holding suction.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;All suggestions welcome.&lt;/p&gt;&#xA;" OwnerUserId="7487" LastEditorUserId="65" LastEditDate="2015-03-09T19:58:48.767" LastActivityDate="2020-12-18T12:44:19.310" Title="How can I check pitot static leak without a test box?" Tags="&lt;flight-instruments&gt;&lt;pitot-static&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13044" PostTypeId="2" ParentId="13043" CreationDate="2015-03-04T22:40:18.167" Score="4" Body="&lt;p&gt;There are lots of challenges to testing a static system the way you describe.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, you need something to fit over the static port (not too hard if it's a single fuselage port, slightly more difficult if it's two of them, and if it's on a mast like on some Piper aircraft you just lost a lot of &quot;seal area&quot; and made the task very difficult).&lt;br&gt;&#xA;You can get around that with test kits by taking the static line(s) off &amp;amp; screwing the test kit directly to the plumbing, or by using a variety of adapters that come with the kits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, you need to produce a known absolute pressure in the line and hold it for a given duration to check for leaks.&lt;br&gt;&#xA;That's most of what those fancy boxes do - they bring the line to a given pressure altitude, and then you watch the altimeter and/or line pressure to see if it leaks air back into the system.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All that said, if you're willing to deal with a really rough test, you can still do this with a syringe and some medical tubing. &lt;a href=&quot;http://rv-12-n419aj.blogspot.com/2014/04/test-pitot-and-static-air-systems.html&quot; rel=&quot;nofollow&quot;&gt;This RV-12 builder shows you how&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Attach a syringe to some surgical tubing.&lt;/li&gt;&#xA;&lt;li&gt;Put some air-tight tape over your other static port (if applicable)&lt;/li&gt;&#xA;&lt;li&gt;Put some modeling clay around the static port.&lt;br&gt;&#xA;&lt;strong&gt;&lt;em&gt;DON'T&lt;/em&gt;&lt;/strong&gt; get it in the hole - make kind of a cup &lt;em&gt;around&lt;/em&gt; the hole.&lt;/li&gt;&#xA;&lt;li&gt;Put the surgical tubing into the modeling clay and press the clay tight around the tube to seal the chamber over the static port.&lt;/li&gt;&#xA;&lt;li&gt;Pull on the syringe until you &quot;climb&quot; to a convenient altitude.&lt;/li&gt;&#xA;&lt;li&gt;Hold or lock the syringe in place and watch the altimeter to see how long it takes for air to leak into the system and lower your altitude.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This is nowhere near as precise as proper calibrated test equipment, but it should help you detect a gross leak in the static system.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-04T22:40:18.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13045" PostTypeId="2" ParentId="2443" CreationDate="2015-03-04T23:43:54.457" Score="-7" Body="&lt;p&gt;ELTs do not normally use GPS. There are newer GPS reporting devices that do use GPS, although they cost more. They work inside vehicles because the signal goes through the window. Commercial planes usually have 2 of them, one in the tail and another portable one in a forward locker or bin. Feel free to bring a bag of them onboard. Do not accidentally activate it or you will piss people off big time. They are designed to work in water and are automatically activated when submerged.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-05T19:05:27.767" LastActivityDate="2015-03-05T19:05:27.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13046" PostTypeId="2" ParentId="13042" CreationDate="2015-03-05T00:10:55.243" Score="15" Body="&lt;p&gt;From my training, the limits on the PT6 use of avgas is related to its ability to lubricate the engine's fuel pumps, and the lead fouling of the hot section  which will result from the avgas. I can't say about other engine's tolerances, but some military jet fuels have much more volatile components than straight kerosene and marine gas turbines run on diesel. A turbine's fuel isn't always decided by what it can burn, but by what it's practical and economic to feed it. &lt;/p&gt;&#xA;" OwnerUserId="7487" LastActivityDate="2015-03-05T00:10:55.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13047" PostTypeId="2" ParentId="13037" CreationDate="2015-03-05T00:15:54.940" Score="15" Body="&lt;p&gt;I'll answer from a US perspective, since that's where most of the studies I've seen come from, coupled with working in the US system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll point out a few areas the statistics possibly show issues. There are less than 15,000 controllers in the US(estimated, from memory and older sources). Most other professions usually are far larger, and such that an occurrence/issue in the controller population often pushes it higher in statistics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, it is a very demanding job, and a very demanding training environment at a lot of facilities. In the past, if you had 3 losses of separation, within a year, you would be penalized big time, to either a lower facility, or to firing, this increases the stress level in the past studies. The punitive nature has changed to a different system, that doesn't fire someone, unless if it was blantant disregard of the rules, but an incident(loss of separation to accident or any thing else) still can take the toll on a person. In training, you're pushed to be perfect, in terms of spacing, to phraseology, to procedures, to complex airspace, to vast rule books.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule books, if printed out, are generally 500-700 pages each. There's ~3-4 main ones, and tons of little ones. The rules are in a continous change state, and where one thing is legal one day, could be completely changed over the course of a week(rare, but it has happened). Plus each facility has numerous procedure documents and letters of agreements with facilities or agencies that they have to work with. This makes a controler have to have a vast knowledge of rules and how they all interact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Routine situations, even with lots of traffic become easy to handle, once you know what to do and when. It's when the **** hits the fan, that it becomes stressful, whether it's student pilots, language barriers, emergiencies(and there's various kinds that either don't phase you or those that can completely wreck you), to the worst thing, weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's other reasons that it can be highly stressful, from medical rules, to just raw work rules and management issues. &lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-03-05T00:15:54.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13048" PostTypeId="2" ParentId="13042" CreationDate="2015-03-05T00:39:54.313" Score="102" Body="&lt;p&gt;You can persuade a turbine engine to run on just about anything that can burn. So the decision of which fuel to actually use depends on the side factors including, but not limited to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;availability&lt;/li&gt;&#xA;&lt;li&gt;cost&lt;/li&gt;&#xA;&lt;li&gt;emissions&lt;/li&gt;&#xA;&lt;li&gt;hot section temperature&lt;/li&gt;&#xA;&lt;li&gt;chemical reactions with engine parts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Specific examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Coal dust is rather difficult to pump around, and the rampies don't like shovelling&lt;/li&gt;&#xA;&lt;li&gt;liquid hydrogen (used in the Space Shuttle) requires a lot of storage and has the nasty habit of freezing anything it touches, like rampies.&lt;/li&gt;&#xA;&lt;li&gt;ethylacetylenedecaborane is unpleasantly toxic (rampies union again) and the combustion byproducts were rather abrasive to the engine's innards&lt;/li&gt;&#xA;&lt;li&gt;trimethylaluminum would reduce the engine complexity (no igniters needed) because it has the nasty habit of igniting instantly upon contact with air, so leaks are rather dangerous.&lt;/li&gt;&#xA;&lt;li&gt;natural gas is commonly used as a turbine fuel in pumping stations: it's already there and thus is &quot;free&quot;. The required pressure vessels make it impractical to use as an aircraft fuel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So kerosene basically became the standard turbine fuel because it's:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;cheap: kerosene makes up a rather large fraction of crude oil. When you measure your fuel load in tons a few cents per litre makes a difference.&lt;/li&gt;&#xA;&lt;li&gt;safe to handle: relatively non-toxic, doesn't ignite all that easily&lt;/li&gt;&#xA;&lt;li&gt;storable and transportable in common structural metals&lt;/li&gt;&#xA;&lt;li&gt;doesn't clog up the engine&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2017-09-21T23:11:33.470" LastActivityDate="2017-09-21T23:11:33.470" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="13049" PostTypeId="2" ParentId="12747" CreationDate="2015-03-05T01:01:16.913" Score="0" Body="&lt;p&gt;Be forewarned: I hold a multi-engine instrument rating but can no longer fly due to the loss of my medical certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I attended Embry-Riddle Aeronautical University through an extension campus at Hillsboro Aero Academy. I completed all of my flight tests and exams in the minimum required time. I had the entire staff behind me when confronting the FAA on the matter of ADD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the FAA's requirements to get a waiver are quite strict (which includes taking the Wisconsin card sorting test before acquiring a medical certification). According to the three psychologists that I visited in trying to acquire a waiver, the tests are difficult to pass for even the most focused individuals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My recommendation is to not say anything. I didn't at first and that's how I got so far. It was only when trying to get a class 1 medical certificate that I admitted to having once been diagnosed with ADD. I hadn't taken any medication in five years at that point and had no symptoms, but few psychologists will un-diagnose you due to the severe liability it could pose on them and others. I spent thousands of dollars trying to acquire a waiver and invoked the AOPA legal insurance that I had, but nothing helped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA's job is to deny you. Until these things are looked at more seriously by the FAA, I would suggest not saying anything. &lt;/p&gt;&#xA;" OwnerUserId="7519" LastEditorUserId="7348" LastEditDate="2015-10-13T19:27:42.113" LastActivityDate="2015-10-13T19:27:42.113" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13050" PostTypeId="2" ParentId="13037" CreationDate="2015-03-05T03:01:19.077" Score="4" Body="&lt;p&gt;ATC controllers have to deal with high stakes, high risk, and limited senses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot has final say over what happens on his plane, but the ATC gives quite strong commands to a pilot.  ATC is &quot;the birds eye view&quot; of the sky, and as such, their opinion over what should happen carries a remarkable amount of sway.  A bad command could put a pilot in a particularly bad place where correcting the situation could tax the physical capabilities of the airplane as the pilot acts to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also in a very monetarily important position.  They are responsible for getting as many planes as possible landing or taking off, given resource constraints like &quot;runways.&quot;  Being cautious can cost large companies a great deal of money, so there is a strong incentive to allow as many planes per hour as possible.  This raises the stakes, as you have more opportunities to fail to properly juggle a large volume of information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the viewpoint and control you have is limited.  You have a radar view, and a radio to communicate.  Compared with the amount of activity going on, those tools are quite limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the rest of the sky, there's enough space to get the planes separated and establish simpler rules which keep people safe.  In these focused areas of complexity around the airports, we rely on ATC to make sure nothing goes wrong.&lt;/p&gt;&#xA;" OwnerUserId="6873" LastActivityDate="2015-03-05T03:01:19.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13051" PostTypeId="1" AcceptedAnswerId="13055" CreationDate="2015-03-05T04:47:11.457" Score="5" ViewCount="852" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BGee4.jpg&quot; alt=&quot;A Gear box plate without SPEC and SER numbers&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Aiwdl.jpg&quot; alt=&quot;A Gear box plate without SPEC and SER numbers&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These pictures are of a plate from WWII US military plane that crashed in the high mountains of central Japan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;People living there say that after the war officials recovered the crash sites and some parts were put on display in a museum nearby.  This plate is attached to a small metal box which is part of the museum collection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It says &quot;gear box type JH-1045&quot; manufactured by &quot;Jack &amp;amp; Heintz, Cleveland Ohio&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But SPEC. and SER. are blank.  I assume these are where the spec number and serial number should go?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like somebody carefully cut those parts off the plate.  People there say that was not done after the recovery, so the plane was flying with this plate as it is.  Nobody remembers the type of aircraft nor where the rest of the wreckage went.  I do not know whether the numbers were scraped off before flight or were just originally not there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are these spec and serial numbers blank on the parts plate of a WWII US military plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regards,&#xA;Naoya&lt;/p&gt;&#xA;" OwnerUserId="7372" LastEditorUserId="15696" LastEditDate="2017-11-06T15:20:29.363" LastActivityDate="2017-11-06T15:20:29.363" Title="Why are these spec and serial numbers blank on a part's plate of a WWII US military plane?" Tags="&lt;aircraft-structures&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13052" PostTypeId="1" AcceptedAnswerId="13053" CreationDate="2015-03-05T07:01:56.867" Score="19" ViewCount="4408" Body="&lt;p&gt;A Turkish Airlines flight &lt;a href=&quot;http://avherald.com/h?article=482a5e9e&amp;amp;opt=0&quot;&gt;recently ran off the runway&lt;/a&gt; and ended up on its belly in a field. The landing gear were damaged, but the plane didn't burn and the fuselage remained intact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are planes involved in this sort of accident repaired and returned to service, or are the planes usually scrapped?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2518" LastEditorUserId="2518" LastEditDate="2015-03-05T22:05:21.570" LastActivityDate="2015-03-05T22:05:21.570" Title="Do planes return to service after non-fiery crashes?" Tags="&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;runway-incursion&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13053" PostTypeId="2" ParentId="13052" CreationDate="2015-03-05T07:40:54.170" Score="20" Body="&lt;p&gt;If the aircraft can be economically repaired (there is no major structural damage, and we're not talking about an aircraft already scheduled to be retired) then it's likely the aircraft will be repaired and returned to service. When you spend several million on an aircraft you aren't going to throw it away for a few tens or hundred thousand dollars worth of damage, particularly as it's probably insured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is structurally compromised to the point where repairs would not be economical (or if we're talking about an older aircraft which has given many years of service and is due for retirement) it would probably be written off and scrapped for any salvageable parts (either repairing it to a condition where it could be ferried to a &quot;&lt;a href=&quot;http://www.johnweeks.com/boneyard/&quot;&gt;boneyard&lt;/a&gt;&quot; or dismantled and cut up at the accident site - whichever option is less expensive for the airline).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As one particularly famous datapoint, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot;&gt;Gimli Glider&lt;/a&gt; had an off-airport landing with a nose gear collapse in 1983. The aircraft was repaired, returned to service, and flew until 2008 (a little under 25 years of additional service after its incident).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-05T07:40:54.170" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13055" PostTypeId="2" ParentId="13051" CreationDate="2015-03-05T09:39:56.313" Score="11" Body="&lt;p&gt;I suspect the reason for this has nothing do with aviation and better fits at our history or statistics stackexchange counterparts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Information about the production capacity of the enemy is of major strategic importance. Using the serial numbers of a relative few aircraft one can make a quite accurate estimate of the total number of aircraft produced. This was found out during world war II and is known as the &lt;a href=&quot;http://en.wikipedia.org/wiki/German_tank_problem&quot;&gt;German tank problem&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I suspect is that after this methodology was developed, producers were asked to withheld the serial numbers from their products and/or replace them by a cryptographic equivalent.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-03-05T09:39:56.313" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13056" PostTypeId="2" ParentId="13052" CreationDate="2015-03-05T10:06:28.957" Score="8" Body="&lt;p&gt;Yes, some even after a fairly fiery crash. Here are some &lt;a href=&quot;http://exposurealaska.com/ice/lidia%20recovery,%20antarctica/index.html&quot;&gt;photos&lt;/a&gt; and a &lt;a href=&quot;https://www.youtube.com/watch?v=MOwQuQfquRI&quot;&gt;video&lt;/a&gt; illustrating some very interesting cases (ALCI Lidia 2012-13 crash and recovery and ALCI Mia accident in 2009).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avcanada.ca/forums2/viewtopic.php?f=25&amp;amp;t=94326&quot;&gt;Here&lt;/a&gt; they even say that the airframe was totaled ten years prior to &lt;em&gt;this&lt;/em&gt; accident and repaired a year after that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit&lt;/em&gt;: Factual corrections about the video (thank you @DeltaLima).&lt;/p&gt;&#xA;" OwnerUserId="4291" LastEditorUserId="65" LastEditDate="2015-03-05T14:12:23.600" LastActivityDate="2015-03-05T14:12:23.600" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13058" PostTypeId="2" ParentId="341" CreationDate="2015-03-05T12:12:41.400" Score="1" Body="&lt;p&gt;The main problem in Type-1 DM is that anything that increases the body Glucose consumption may yield a potentially obtunding and sometimes deadly too low blood Glucose levels (Hypoglycemia in medical terms), this may come from a physical exercise while on the usual Insulin dose, and also from the mental stress from piloting, that may increase the Glucose consumption and lead to the catastrophic event of a loss of conscience, a blackout, or death while in command of an airplane. Automated Glucose monitoring devices that act mimicking the Pancreas islet cells function, measuring in a continued real time blood glucose levels, and releasing Insulin to the blood in accordance, are under strong research by many, but as in both T-I and T-II DM, (DM may be considered a mainly self-managed disease), the race is against the long term complications from poor, too high or too unsteady blood Glucose levels control, a too low blood Glucose level is an immediate life-threatening situation. People suffering T1DM must acknowledge that some activities are too dangerous for them and in certain circumstances for those close to them, at least in the current state of the medical arts, and thus, T1DM patients better refrain from engaging in some types of risky activities. Acting as an Airplane pilot is one of it.&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-03-05T12:12:41.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13060" PostTypeId="2" ParentId="13037" CreationDate="2015-03-05T13:49:09.057" Score="11" Body="&lt;p&gt;&quot;Air Traffic Controller&quot; is a poorly understood job and isn't personally dangerous. The member of the general public has little knowledge apart from its listing as extremely stressful (top five!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The perception may well be accurate, but the perception itself is based on this combination:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Air traffic controller&quot; shows up in mass media lists of &quot;most stressful jobs&quot; (&lt;a href=&quot;http://www.csmonitor.com/USA/2010/0811/Top-5-most-stressful-jobs/Air-traffic-controller&quot; rel=&quot;noreferrer&quot;&gt;one example&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;It does not share the perception of danger that other stressful jobs do.&lt;/li&gt;&#xA;&lt;li&gt;The general public has very little ability to relate to the job.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the example link above, the five most stressful jobs are&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Inner-city High School Teacher&lt;/li&gt;&#xA;&lt;li&gt;Police Officer&lt;/li&gt;&#xA;&lt;li&gt;Miner&lt;/li&gt;&#xA;&lt;li&gt;Air Traffic Controller&lt;/li&gt;&#xA;&lt;li&gt;Medical Intern&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The police officer and miner definitely have the perception of incurring personal danger. So I would bet that police officers and miners get asked, &quot;Isn't that a dangerous job?&quot; before they're asked if it's stressful. Inner-city High School Teachers probably share some of the perception of personal danger as &quot;the inner-city&quot; is stereotypically dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Inner-city High School Teacher&quot; and &quot;Medical Intern&quot; are both part of helping professions where the vast majority of people have been on the receiving end of direct contact (as a student and patient). Conversation topics can cover many aspects of these professions before the member of the general public can no longer relate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Air Traffic Controller&quot;? Um, that must be a stressful job, huh?&lt;/p&gt;&#xA;" OwnerUserId="7524" LastEditorUserId="7524" LastEditDate="2015-03-05T14:50:15.920" LastActivityDate="2015-03-05T14:50:15.920" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13062" PostTypeId="2" ParentId="13052" CreationDate="2015-03-05T16:00:22.573" Score="2" Body="&lt;p&gt;I don't know about large aircraft, but for smaller aircraft it is usually dependent on whether a structural member was damaged, especially a bulkhead. If a structural member is bent or crushed, then usually a small plane will be unsalvageable, but if structural members are intact and undamaged, then usually the aircraft can be repaired.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-05T16:00:22.573" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13064" PostTypeId="2" ParentId="13025" CreationDate="2015-03-05T18:23:05.747" Score="14" Body="&lt;p&gt;If the helicopter is operating at an airport, it needs clearance like a regular flight, otherwise it would be a very dangerous situation for the helicopter and any other traffic in the area. Usually the ATC will give priority to the emergency helicopter (as much as possible), so it will leave the area without delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the weather conditions, there are two aspects that need to be considered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The regulations allow emergency helicopters to fly VFR below VMC minima (this is true in Europe, I have no idea about FAA). So, an emergency helicopter, can continue VFR with visibility down to 1km, or even 800 meters for short periods of time.&lt;/li&gt;&#xA;&lt;li&gt;If the helicopter is IFR equipped and the pilot(s) IFR rated, it can switch to IFR if necessary. On the way to the accident site this might not be very useful if the weather will not allow safe descent and switch to VFR, but on the way back to the airport/hospital, it can be very useful, provided the landing site has some kind of IFR procedure. Again, ATC will usually offer full cooperation in all this switching of plans and flight rules.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2532" LastEditorUserId="65" LastEditDate="2015-03-05T19:26:43.287" LastActivityDate="2015-03-05T19:26:43.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13065" PostTypeId="2" ParentId="1147" CreationDate="2015-03-05T19:14:37.923" Score="3" Body="&lt;p&gt;Commercial aircraft do transmit a limited amount of data via &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;nofollow&quot;&gt;ACARS&lt;/a&gt;. This information can only be received line of sight, so if the aircraft is over the ocean the information will not be received (except by a ship that might be randomly listening).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information on a flight data recorder is stored to a tape or other high-density storage and contains gigabytes of information. It would be impossible to transmit this much data via a normal radio due to insufficient bandwidth. You could potentially transmit this much data with a microwave link, but this would require a complicated satellite-based system. Military drones, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk&quot; rel=&quot;nofollow&quot;&gt;Global Hawk&lt;/a&gt;, do make such transmissions (the big dome on top is the microwave antenna). Even if you equipped commercial aircraft with such bulky transmitters, you would need to launch thousands of new satellites to listen to and receive all the transmissions from the thousands of planes. So, while it may be technically possible, the cost and complexity of such a system is way beyond what is currently viable.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-05T19:14:37.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13066" PostTypeId="1" AcceptedAnswerId="13075" CreationDate="2015-03-05T20:15:56.750" Score="13" ViewCount="1860" Body="&lt;p&gt;I understand hail can be very damaging to an aircraft, in particular to the engines and windshield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event that a windshield becomes cracked so that visibility is impossible, can pilots pop out the windows when at a lower enough altitude in order to see the runway?&lt;/p&gt;&#xA;" OwnerUserId="3355" LastEditorUserId="1696" LastEditDate="2015-10-07T14:40:32.677" LastActivityDate="2015-10-07T14:40:32.677" Title="How can an airplane land if a hail storm damages the windshield?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;weather&gt;&lt;windows&gt;" AnswerCount="6" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13067" PostTypeId="1" AcceptedAnswerId="13069" CreationDate="2015-03-05T20:44:33.280" Score="13" ViewCount="1694" Body="&lt;p&gt;When thunderstorms or other severe weather crop up, will the Air Traffic Control in the area proactively route traffic (horizontally or vertically) around the trouble area, or do they leave it up to the individual pilots to request an alternate route?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My intent was asking about &lt;a href=&quot;http://en.wikipedia.org/wiki/Commercial_aviation&quot;&gt;commercial aircraft&lt;/a&gt; flying &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_flight_rules&quot;&gt;IFR&lt;/a&gt;, however the information about &lt;a href=&quot;http://en.wikipedia.org/wiki/General_aviation&quot;&gt;general aviation&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Visual_flight_rules&quot;&gt;VFR&lt;/a&gt; is appreciated&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-03-05T21:36:17.183" LastActivityDate="2015-03-08T23:27:47.023" Title="Will ATC proactively route traffic around bad weather?" Tags="&lt;air-traffic-control&gt;&lt;weather&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13068" PostTypeId="2" ParentId="13067" CreationDate="2015-03-05T21:02:12.607" Score="-3" Body="&lt;p&gt;Pilots do not &quot;request routes&quot; except when entering or exiting congested air space, or Class A air space or IFR conditions. They optionally notify ATC of where they might be going by filing a &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_plan&quot; rel=&quot;nofollow&quot;&gt;flight plan&lt;/a&gt;. VFR pilots can also request &lt;a href=&quot;http://www.avweb.com/news/avtraining/183268-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;flight following&lt;/a&gt;. When flight following is activated ATC will notify you of other aircraft or weather conditions that could cross your path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In uncontrolled airspace, ATC will notify you of a dangerous condition if you are on a flight plan that would bring you into contact with dangerous weather or have flight following activated. It is up to the pilot to decide what to do with that information. In controlled commercial airspace (Class A), ATC will actively route aircraft around dangerous weather conditions.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-05T21:30:00.877" LastActivityDate="2015-03-05T21:30:00.877" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="13069" PostTypeId="2" ParentId="13067" CreationDate="2015-03-05T21:02:20.453" Score="14" Body="&lt;h1&gt;Yes, ATC will reroute flights that are operating on &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;noreferrer&quot;&gt;Instrument Flight Rules (IFR)&lt;/a&gt;.&lt;/h1&gt;&#xA;&lt;p&gt;There are lots of videos of &lt;a href=&quot;https://www.youtube.com/watch?v=eWv4wyy_Jqg&quot; rel=&quot;noreferrer&quot;&gt;flights getting routed around severe weather&lt;/a&gt; floating around on the internet! Atlanta is a great example, as is &lt;a href=&quot;https://www.youtube.com/watch?v=J-qPtWc4heA&quot; rel=&quot;noreferrer&quot;&gt;Memphis, FedEx's hub&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;In addition, &lt;a href=&quot;http://www.aviationsystems.arc.nasa.gov/research/strategic/dwr.shtml&quot; rel=&quot;noreferrer&quot;&gt;NASA is working on a product called Dynamic Weather Routes&lt;/a&gt; that will help controllers be smarter about amending planned or unplanned weather reroutes.&lt;/p&gt;&#xA;&lt;h1&gt;Sort of, for aircraft operating VFR.&lt;/h1&gt;&#xA;&lt;p&gt;VFR flights that are talking to ATC may get advisories about weather and suggested headings from the controller. I've received notifications about things like 'moderate to heavy precipitation 5-10 miles ahead' many times when operating on VFR flight following.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-05T21:17:05.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13070" PostTypeId="2" ParentId="13067" CreationDate="2015-03-05T21:19:18.293" Score="9" Body="&lt;p&gt;The system is a combination of both. The controller will have a view of the weather radar for the area, and can route traffic around bad areas. They will at least advise the pilots of the bad weather that they can see, and can offer the pilots a deviation or let them know what previous flights have done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the pilots have a better view with the weather radar on their plane, and the pilots have the ultimate decision as to what they will do. The pilots may see a weather return they don't like and ask for deviation around it. Even if ATC denies the request, the pilots are ultimately responsible for the safety of the flight, and should do what they feel is best, even if that means &lt;a href=&quot;http://avherald.com/h?article=47a1e4e6&quot;&gt;deviating without permission&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an interesting article &lt;a href=&quot;http://www.avweb.com/news/sayagain/182640-1.html&quot;&gt;here&lt;/a&gt; that is a bit dated, but should still apply to the general idea of how ATC handles bad weather.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-03-05T21:19:18.293" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13071" PostTypeId="2" ParentId="13066" CreationDate="2015-03-05T21:58:17.430" Score="-3" Body="&lt;p&gt;Commercial aircraft pilots are required to pass an &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_rating&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Instrument Flight Rules&quot; (IFR) rating&lt;/a&gt;.  This rating requires the pilot to flight their aircraft using just the instruments in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to how will the pilot know where to land.  Commercial and military aircraft possess multiple instruments to provide location information.  This includes GPS based instruments.  I believe that this still includes &lt;a href=&quot;http://en.wikipedia.org/wiki/VOR/DME&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR/DME (VHF omnidirectional range/distance measurement equipment)&lt;/a&gt; too but I've been out of the industry for a couple of decades and these may no longer be included.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At commercial &amp;amp; military aircraft flight speeds, busting out your windscreen would be a terribly bad idea - probably fatal.  It would certainly make it so you wouldn't be able to land the plane.  A better choice for non-instrument rated pilot would be to have the tower talk you in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per this other &lt;a href=&quot;https://aviation.stackexchange.com/questions/9633/how-can-landing-in-zero-visibility-be-safe&quot;&gt;SE question &amp;amp; answer&lt;/a&gt;, although a true zero-zero landing is actually possible and safe to perform (provided &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS equipment&lt;/a&gt; is installed in aircraft and airport), there are problems on the ground with rollout and maneuvering on the ground which for practical purposes eliminate it except under extreme circumstances.&lt;/p&gt;&#xA;" OwnerUserId="7526" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-05T22:10:50.340" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13073" PostTypeId="1" AcceptedAnswerId="13077" CreationDate="2015-03-05T23:38:47.943" Score="12" ViewCount="1080" Body="&lt;p&gt;Radar is based on the principle of transmitting radio waves and measuring the length of time-of-flight, direction, and frequency shift of the returning reflections or echoes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation, we call this &quot;primary radar&quot; and we use the term &quot;secondary radar&quot; to denote the ATC/transponder system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondary radar uses a transmitter that sends pulses that the transponder picks up and then sends coded pulses of its own back. But these are not based on reflections off the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why then call the ATC/transponder system &quot;secondary radar&quot; when the principle is very different from what we might call &quot;real&quot; (aka primary) radar?  Or does the &quot;secondary&quot; here meaning &quot;in addition to&quot; rather than &quot;another form of&quot;?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-03-06T00:14:27.167" LastActivityDate="2015-03-06T23:22:45.427" Title="Is &quot;secondary radar&quot; a misnomer?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;&lt;radar&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13074" PostTypeId="2" ParentId="13042" CreationDate="2015-03-06T00:52:09.920" Score="5" Body="&lt;p&gt;The very high temperatures of jet engines cause gasoline to be a poor fuel because it tends to burn too fast.  Kerosene, which is routinely called &quot;Fuel OIL&quot; some places, avoids pre-ignition problems (and some safety hazards) just like higher-octane gas avoids spark-plug knocking.  The ultimate control of ignition comes from using Diesel Fuel (which ALSO is routinely called Fuel Oil some places), and that's why big trucks use Diesel: that control gives them the best fuel efficiency their engines can have; but Diesel wont' run a jet engine.  Gasoline is too volatile for a jet engine; Diesel fuel is not volatile ENOUGH for a jet.&lt;/p&gt;&#xA;" OwnerUserId="7535" LastActivityDate="2015-03-06T00:52:09.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13075" PostTypeId="2" ParentId="13066" CreationDate="2015-03-06T00:53:55.647" Score="11" Body="&lt;p&gt;In the EMB-145 the abnormal procedure for obscured windscreens is to secure items in the cockpit, open the side window and look through its opening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more aircraft that share this procedure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the QRH procedure for &quot;Impaired or cracked windshield&quot; in the EMB-145:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Associated Windshield Heating .............................. OFF&#xA;&#xA;IF  only the outer layer (glass) is cracked, no action is &#xA;    required&#xA;&#xA;IF  inner layer of glass is cracked, proceed as follows:&#xA;    Cockpit Door ......................................... CLOSE&#xA;    Maximum Altitude ....................... 10,000 FT., OR MEA,&#xA;                                             WHICHEVER IS HIGHER&#xA;    Pressurization Manual Controller ........ 1 O'CLOCK POSITION&#xA;&#xA;                    Wait 15 Seconds&#xA;&#xA;    Pressurization Mode Selector ........................... MAN&#xA;    Cabin Delta-P ........................... SET EQUAL TO 1 PSI&#xA;&#xA;    Note:  Pressurization Manual Controller must be used to set&#xA;           and maintain Cabin Delta-P at 1 psi while descending&#xA;&#xA;    Airspeed .................................... BELOW 250 KIAS&#xA;    Smoke Goggles .......................................... DON&#xA;    In case both windshields are impaired:&#xA;    Cabin (below 10,000 ft) ....................... DEPRESSURIZE&#xA;    Airspeed ................................. MAXIMUM 140 KIAS,&#xA;                                                    MINIMUM Vref&#xA;&#xA;IF  forward view through both wind screens is impossible, secure&#xA;    loose objects in cockpit and proceed:&#xA;&#xA;    Note:  Intercommunication will be impossible with window &#xA;           removed.&#xA;&#xA;    Direct Vision Window ................................ REMOVE&#xA;    Landing must be made looking through the direct vision &#xA;    window&#xA;&#xA;                              * * * *&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-04-23T13:14:01.343" LastActivityDate="2015-04-23T13:14:01.343" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13077" PostTypeId="2" ParentId="13073" CreationDate="2015-03-06T01:04:10.820" Score="11" Body="&lt;p&gt;The terminology is a combination of history and &quot;trustworthiness&quot; (for lack of a better term).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, primary radar was invented first. So it makes sense that this would be called &quot;primary&quot; and another scheme invented later would be called &quot;secondary&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC systems like to ensure that the data they are working with is trustworthy. Primary radar systems are based only on the reflected radar signals. If you get a reflection, you &lt;em&gt;know&lt;/em&gt; there is something there, whether or not it has a transponder (or indeed, whether or not it is an aircraft). This is a certainly a key point in military radar systems, and ATC radar was derived directly from military radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With secondary radar (transponder) operation, there is no guarantee that the transponder isn't lying (whether deliberately or unintentionally). A faulty transponder could certainly report false locations to the ATC system. Or, you can probably imagine scenarios where a false location might be deliberately returned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC systems take both the primary and secondary location information for an aircraft, and correlate them to represent one aircraft in the sky. They don't report the exact same physical location, so there is a degree of fuzziness in the system to account for that. If the two reported locations drift too far apart, you get an uncorrelated track. Sometimes, if two aircraft cross each other's track in certain ways, the ATC system can get confused and associate the wrong primary radar blip with the wrong transponder report. The controllers have procedures to deal with and correct these kinds of problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, primary radar is primary because it (a) came first, and (b) is the most trustworthy source of aircraft location information. Secondary &quot;radar&quot; (which, as you point out, is not really &lt;em&gt;radar&lt;/em&gt;) is called such because it is integrated within the primary radar system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More generally, the various technologies for locating and identifying aircraft in airspace are collectively called &quot;surveillance&quot;. Examples of ATC surveillance are primary radar, transponders, multilateration, ACARS position reports, and other technologies.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="675" LastEditDate="2015-03-06T01:13:10.713" LastActivityDate="2015-03-06T01:13:10.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13078" PostTypeId="2" ParentId="13042" CreationDate="2015-03-06T01:13:11.800" Score="26" Body="&lt;p&gt;In a modern turbofan engine, fuel is not only burned in the engine and used to lubricate parts such as fuel pumps and controls, it is used as a &lt;a href=&quot;https://books.google.com/books?id=2Wy5rpdm3DMC&amp;amp;lpg=PA676&amp;amp;ots=5e-KlZb6U7&amp;amp;dq=jet%20engine%20variable%20inlet%20guide%20vane%20fuel%20hydraulic&amp;amp;pg=PA676#v=onepage&amp;amp;q=jet%20engine%20variable%20inlet%20guide%20vane%20fuel%20hydraulic&amp;amp;f=false&quot;&gt;&lt;em&gt;hydraulic fluid&lt;/em&gt;&lt;/a&gt; as well -- this is used to power things like inlet guide vanes and variable stator vanes in many engines, as well as more exotic accessories such as movable nozzles and inlet ramps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that gasoline is often not tolerated by larger aviation turbines, as it boils at such a low temperature that it could boil off inside fueldraulic (or other fuel system) parts and interfere with their operation, atop the lubricity and lead fouling issues that it obviously would pose.  Even wide-cut jet fuels such as JP-4 and Jet-B are prohibited for service in some larger turbofans due to the volatility issues they pose (this is a quote from the 777 QRH Limitations section):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The use of JP–4 and Jet B fuels is prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-03-06T01:13:11.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13079" PostTypeId="1" AcceptedAnswerId="13086" CreationDate="2015-03-06T01:31:55.170" Score="2" ViewCount="766" Body="&lt;p&gt;How would an individual pilot operating under Part 91 in a light aircraft with a future &quot;glass cockpit&quot; setup (maybe Garmin will add it to the G2000?) capable of coding and flying &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0102.html&quot; rel=&quot;nofollow&quot;&gt;RNAV (Area Navigation) and RNP (Required Navigation Performance)&lt;/a&gt; approaches with the necessary precision and accuracy (incl. Radius to Fix legs) go about gaining authorization to fly them?  Or would such a system require a blanket authorization from the FAA that says that &quot;all users of such-and-such system flying under Part 91 are authorized to fly RNP approaches using the procedure in the system manual&quot;?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="19" LastEditDate="2016-07-14T08:02:03.767" LastActivityDate="2016-07-14T08:02:03.767" Title="How can a part 91 operator gain authorisation from the FAA to perform RNAV (RNP AR) approaches?" Tags="&lt;navigation&gt;&lt;instrument-procedures&gt;&lt;far-91&gt;&lt;glass-cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13081" PostTypeId="1" AcceptedAnswerId="13082" CreationDate="2015-03-06T03:24:18.123" Score="9" ViewCount="4919" Body="&lt;p&gt;I have heard it said that all aviation regulations are &quot;written in blood&quot;. I think this means that every rule in the book exists because someone died - and there was a lesson learned. Is this accurate? Is there anything else to the story of this phrase?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2020-05-07T01:15:27.460" Title="Why do people say aviation regulations are written in blood?" Tags="&lt;regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13082" PostTypeId="2" ParentId="13081" CreationDate="2015-03-06T03:53:32.767" Score="12" Body="&lt;p&gt;No, that's all it means. Aviation regulations tend to be put in place in response to accident reports, where a plane crashed or almost crashed for lack of the regulations. So, if you're confused why a stupid-seeming regulation exists, there's a good chance that people died because of the thing the regulation changed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, not &lt;em&gt;all&lt;/em&gt; regulations are like that; for instance, noise limits are based on quality of life for those near airports, not crashes. However, a good number of aviation rules came into effect as recommendations following a crash report.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-03-06T03:53:32.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13083" PostTypeId="1" AcceptedAnswerId="13085" CreationDate="2015-03-06T04:11:08.077" Score="5" ViewCount="6214" Body="&lt;p&gt;The reason I ask this question is because I am a programmer and developing &lt;a href=&quot;http://en.wikipedia.org/wiki/Extract,_transform,_load&quot; rel=&quot;noreferrer&quot;&gt;ETL&lt;/a&gt; processes to calculate reliability of products that are installed in aircrafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been getting A &lt;strong&gt;lot&lt;/strong&gt; of bad data from the OEMs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been told by an engineer at my organization that the maximum number of flight hours an aircraft can have is 400 hrs a month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this accurate per FAA regulations?&lt;/p&gt;&#xA;" OwnerUserId="7537" LastEditorUserId="62" LastEditDate="2015-03-06T14:34:05.833" LastActivityDate="2016-11-17T17:30:02.123" Title="What is the maximum amount of flight hours an aircraft can have a month?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13084" PostTypeId="2" ParentId="13037" CreationDate="2015-03-06T04:12:18.503" Score="1" Body="&lt;h2&gt;Well, is the job actually stressful?&lt;/h2&gt;&#xA;&lt;p&gt;Whether or not their job is actually stressful is the decision of each individual controller. The job &lt;em&gt;does&lt;/em&gt; attract a certain kind of person...&lt;/p&gt;&#xA;&lt;p&gt;It might be helpful to point out a few reasons why it might or might not be stressful.&lt;/p&gt;&#xA;&lt;p&gt;At the end of the day, thousands of lives &lt;strong&gt;are&lt;/strong&gt; on the line. Zero errors tolerated, 100% performance required, penalties including relatively quick demotion/firing.&lt;/p&gt;&#xA;&lt;p&gt;On the other hand, losing separation doesn't mean a crash. There are tolerances built in to the rules.&lt;/p&gt;&#xA;&lt;p&gt;Working in New York City is going to be more stressful than working in Standard Country Town.&lt;/p&gt;&#xA;&lt;h2&gt;Common misconceptions of ATC&lt;/h2&gt;&#xA;&lt;p&gt;The general public doesn't know that many controllers &lt;em&gt;don't even work at airports.&lt;/em&gt; In reality, the largest facilities are not only located away from airports, they don't even deal with aircraft at airports!&lt;/p&gt;&#xA;&lt;p&gt;This isn't unheard of either:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Air traffic control - those are the guys that wave the red batons at the plane, right?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h1&gt;The bottom line&lt;/h1&gt;&#xA;&lt;p&gt;Aviation can be inherently frightening. Perhaps this contributes.&lt;/p&gt;&#xA;&lt;p&gt;The job is not common; people don't know about it. While ATC is similar to a police officer in some respects (relative boredom with brief times of sheer terror?), police officers are more common and well understood. Perhaps it is a function of familiarity.&lt;/p&gt;&#xA;&lt;p&gt;And perhaps one can't get away from the image of a 747 falling out of the sky and the person who was supposed to &amp;quot;control&amp;quot; it.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-06T04:12:18.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13085" PostTypeId="2" ParentId="13083" CreationDate="2015-03-06T06:07:11.180" Score="10" Body="&lt;p&gt;I don't think there is any regulation on max flying hours, just regulations on &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_maintenance_checks&quot;&gt;maintenance intervals&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_maintenance_checks#A_check&quot;&gt;&quot;A&quot; check&lt;/a&gt; is the most frequent check, and according to Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This is performed approximately every 125 flight hours or 200–400&#xA;  cycles. It needs about 20–50 man-hours and is usually performed&#xA;  overnight at an airport gate or hangar. The actual occurrence of this&#xA;  check varies by aircraft type, the cycle count (takeoff and landing is&#xA;  considered an aircraft &quot;cycle&quot;), or the number of hours flown since&#xA;  the last check. The occurrence can be delayed by the airline if&#xA;  certain predetermined conditions are met.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The other checks include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;B check - every 4–6 months, requiring about 150 man-hours and is usually performed within 1–3 days at an airport hangar&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;C check -  every 20–24 months, requiring about 6000 man-hours, taking 1 to 2 weeks to complete&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;D check - major maintenance check, occuring about every 6 years, requiring 50,000 man hours, generally spanning a couple months.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note that all of these times are approximate, depending on the exact maintenance plan filed by the airline and the aircraft type. Also cycle count may be factored into the maintenance intervals in addition to flight hours so aircraft that do many short-haul flights may have more frequent maintenance.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in any case, only looking at the A checks, if you can land, refuel, service, and get back in the air in 2 hours between 10 hour flights, the plane could stay in the air for 20 hours/day. Every 6 days, it will need some downtime for the A checks, let's say the airline puts enough  people on it to get the check done in 5 hours. So that's 125 hours per cycle: 120 hours flying, 5 hours in maintenance. They can fit 4.83 of these cycles in a 30 day month so the aircraft could be flying up to 580 hours in any given month (but that last A check gets deferred to the next month, so that means less time in the air that month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With longer flights (which reduces the overhead from turnaround times) and tighter turnaround times, the flight hours per month could be higher. If you really want the maximum for a month, then if you assume 125 hours per maintenance inverval and that the plane is kept in the air as long as possible with 0 turnaround time, that's around 690 flying hours out of 720 total hours in a month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this makes a big assumption that the A check interval really is 120 hours, and that the time to do the maintenance is 5 hours, in the real world both numbers will vary based on aircraft, airline, and maintenance staffing levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plus, over the longer term, you need to factor the other, less frequent but also more time consuming maintenance checks (B through D checks), as well as allow downtime for unexpected repairs.&lt;/p&gt;&#xA;" OwnerUserId="1844" LastEditorUserId="1844" LastEditDate="2015-03-06T07:41:27.417" LastActivityDate="2015-03-06T07:41:27.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13086" PostTypeId="2" ParentId="13079" CreationDate="2015-03-06T07:30:23.470" Score="4" Body="&lt;p&gt;I have no practical experience with FAA RNP AR authorization but the guidelines for obtaining RNP AR authorization from the FAA are described in FAA Advisory Circular &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2090-101A.pdf&quot; rel=&quot;nofollow&quot;&gt;90-101A &lt;sup&gt;(FAA PDF)&lt;/sup&gt;&lt;/a&gt;. The whole process to go through is described in that document. It specifically mentions Part 91 and Part 91K (fractional ownership) so it should be possible to obtain permission for individual pilots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it will not be easy for an individual pilot to meet the requirements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will have to perform a high number of RNP AR approaches under a provisional authorization in VMC or increased minima before final authorization is granted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luckily the FAA made provision for operators with a small fleet:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE: In unique situations where the completion of 100 successful&#xA;  approaches could take operators an unreasonably long period of time&#xA;  due to factors such as a small number of aircraft in the fleet,&#xA;  limited opportunity to use runways having appropriate procedures,&#xA;  etc., consideration of a reduction in the required number of&#xA;  approaches will be on a case-by-case basis. The FSDO/CHDO will&#xA;  coordinate with FAA HQ in consideration of an operator’s request for&#xA;  reduced interim authorization requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You will need to arrange proper training:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Initial training:&lt;/strong&gt; With no prior RNP AR approach experience,&#xA;  each pilot&#xA;  must complete at least four RNP AR approach&#xA;  procedures: two as pilot&#xA;  flying and two as pilot&#xA;  monitoring.These four RNP AR&#xA;  approaches shall employ the uni&#xA;  que AR characteristics of the&#xA;  operator’s approved procedures (i.e., RF legs, RNP missed). You must fly two approaches to the DA and two approaches must result in an RNP missed approach procedure. Two of the above approaches will include interrupted approaches resulting in one approach with vectors to resume the approach and one approach resulting in a hold at an initial approach fix (IAF) or transition&#xA;  fix. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And in addition to the a qualifying aircraft the operator must have a program to ensure data the navigation database stays up to date and is of sufficient quality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also need to implement a monitoring program to review your RNP AR approaches and detect any negative trends. Results from this program will need to be shared with the FAA on a monthly basis. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-03-06T07:30:23.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13087" PostTypeId="1" CreationDate="2015-03-06T11:12:42.713" Score="7" ViewCount="698" Body="&lt;p&gt;Altimeters work via an aneroid barometer to sense the atmospheric pressure. If I climb from 2000ft to 4000ft, the altimeter senses that the pressure has reduced by, let's say, 70hpa, and is calibrated to know that 70hpa = 2000ft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the pressure gradient (or rate of change of pressure) reduces with altitude. A climb from FL240 to FL260 might result in a pressure reduction of only 30hpa. Yet it still knows that the aircraft climbed 2000ft. How does the altimeter do this?&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="1696" LastEditDate="2015-03-06T17:19:47.570" LastActivityDate="2015-03-07T14:35:30.240" Title="How does an altimeter deal with the non-linear pressure gradient?" Tags="&lt;flight-instruments&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13089" PostTypeId="2" ParentId="13087" CreationDate="2015-03-06T11:43:49.153" Score="12" Body="&lt;p&gt;It uses a model called &lt;a href=&quot;https://www.aircraftspruce.com/catalog/pdf/13-08715.pdf&quot; rel=&quot;noreferrer&quot;&gt;The International Standard Atmosphere (ISA)&lt;/a&gt; - so may be inaccurate if you don't have one of those to fly through :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IxwuF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-03-06T11:43:49.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13090" PostTypeId="1" AcceptedAnswerId="13091" CreationDate="2015-03-06T11:44:13.170" Score="5" ViewCount="843" Body="&lt;p&gt;To answer my question about the prediction and determination of conflicts, we need a clear definition of the term. As far as I know is the term conflict often mistaken with the term loss of separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me start with the definition of &lt;a href=&quot;http://www.eurocontrol.int/lexicon/lexicon/en/index.php/Conflict&quot; rel=&quot;nofollow noreferrer&quot;&gt;conflict&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Converging&lt;/strong&gt; of aircraft in space and time which constitutes a &lt;strong&gt;predicted&lt;/strong&gt; violation of a given set of separation minima. (emphasis mine)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whereas the definition of a &lt;a href=&quot;http://www.eurocontrol.int/lexicon/lexicon/en/index.php/Loss_of_separation&quot; rel=&quot;nofollow noreferrer&quot;&gt;loss of separation&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A defined loss of separation between airborne aircraft occurs whenever specified separation minima in Controlled Airspace &lt;strong&gt;are&lt;/strong&gt; breached. Minimum separation standards for airspace are specified by ATS authorities, based on ICAO standards. (emphasis mine)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To summarize the matter, a conflict between two aircraft occurs, not when there is a loss of separation, but when there is an &lt;strong&gt;impending&lt;/strong&gt; loss of separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems pretty straightforward, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The challenge is that little word &lt;em&gt;predicted&lt;/em&gt;. Who predicts the &lt;strong&gt;converging&lt;/strong&gt;, when and by which measurements? When does a conflict occur in the eyes of an ATC-controller or a network manager? A related question is &lt;a href=&quot;https://aviation.stackexchange.com/questions/12346/at-what-distance-between-two-aircraft-will-the-air-traffic-controller-get-an-ala/12347#12347&quot;&gt;At what distance between two aircraft will the air traffic controller get an alarm?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this is a rather gray area, where probabilities come into play.&lt;/p&gt;&#xA;" OwnerUserId="3859" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-07T10:45:14.363" Title="How is a &quot;conflict&quot; between aircraft predicted and determined?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;separation&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13091" PostTypeId="2" ParentId="13090" CreationDate="2015-03-06T14:19:15.607" Score="7" Body="&lt;p&gt;It is a bit of a grey area and the answers you'll get will depend also on which field of expertise you are in. I am involved in developing and standardising ATC surveillance systems, here's my take on it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Loss of separation is the simplest definition of the two and it has regulatory consequences. But even that one is not black and white. How do you determine the exact position of two aircraft? Suppose you have a 5 NM radar separation minimum and a radar that has an accuracy of 0.2 NM. If the two aircraft are flying parallel 5.1 NM apart at the same altitude there is a high probability that at some point the difference in radar measurements is less than 5 NM. Is that a loss of separation? To make it even more complex, radar tracking systems lag in turn detection; while an aircraft has started to turn 15 seconds ago, the tracking system may see that as radar measurement noise and may stubbornly paint a straight track depending on the tuning parameters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The definition of conflict you quote has little regulatory meaning but has its roots in workload estimation of aircraft traffic controllers. It is also used in conflict detection systems. Short term conflict detection systems predict the path of aircraft by extrapolating the current position into the future using speed and flight plan, usually augmented by the aircraft traffic controller with cleared altitude, speed, heading etc. If within a predefined time window (approx. two minutes) two aircraft are predicted to be below the separation minimum, an alert is raised. The exact method of prediction varies from system to system. Medium term conflict detection is similar, but depends more on the flight plan than on the current speed vector. The longer term the prediction, the higher probability of a missed conflict or a false alert&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big trick is to design a conflict detection system that has a low missed alert rate (otherwise it isn't effective) and a low false alert rate (otherwise it is a nuisance and will be ignored or turned off) at the same time. It is indeed a trade-off of probabilities. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-07T10:45:14.363" LastActivityDate="2015-03-07T10:45:14.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13092" PostTypeId="2" ParentId="13073" CreationDate="2015-03-06T15:19:22.733" Score="2" Body="&lt;p&gt;The reason why it is called &quot;secondary&quot; radar is because it is in addition to the primary existing radar system, the surveillance system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words even with no transponders the radar system would still exist because large airports and regional zones have air surveillance radars that monitor airspace and show contacts. These contacts include everything that reflects radar energy; not just planes, but birds, even clouds of dust, etc. The is the &lt;em&gt;primary&lt;/em&gt; radar system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The transponders leverage this existing system by transmitting signals these radars can receive and interpret. This allows us to put a bright dot on the screen (and other information like the code) because we &lt;strong&gt;know&lt;/strong&gt; it is an aircraft and it is not, for example, a bird. Because this identification and localization system only works with transponders it is considered a &lt;em&gt;secondary&lt;/em&gt; system. Since the primary radar always works, even if the aircraft does not have a transonder, it is the primary system. It is also primary in the sense that originally there were only surveillance radars; the interrogating radars that receive transponder signals were developed afterwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To further illustrate this, refer to this image of a typical &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control_radar_beacon_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATCRBS&lt;/a&gt; antenna:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/27ZR8.jpg&quot; alt=&quot;ASR-9 Radar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The larger curved antenna is the &lt;strong&gt;PRIMARY&lt;/strong&gt; antenna, it detects aircraft (and everything else, birds, etc) uncooperatively. The smaller, ladder-like antenna on top of the primary is the &lt;strong&gt;SECONDARY&lt;/strong&gt; antenna. This is what is used to detect the transponder's signal. The information from the secondary is then (traditionally) overlaid on the primary's display (although nowadays they are often digitally combined).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-06T23:22:45.427" LastActivityDate="2015-03-06T23:22:45.427" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13093" PostTypeId="1" AcceptedAnswerId="13215" CreationDate="2015-03-06T15:54:38.503" Score="13" ViewCount="4654" Body="&lt;p&gt;And why do military fighters/bomber require so many maintenance hours compared to commercial airlines, &lt;a href=&quot;https://aviation.stackexchange.com/questions/68/who-decides-an-aircrafts-maintenance-schedule&quot;&gt;which seems like just kicking the tires&lt;/a&gt;? &lt;strong&gt;What do they actually &lt;em&gt;do&lt;/em&gt;&lt;/strong&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does maintenance differ for fighters vs. bombers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As many of the comments and answers have illuminated, &quot;different missions drive different design priorities.&quot; Examples of differences in specific maintenance activities would be greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-03-18T13:28:27.990" Title="How does maintenance differ for military fighters/bombers vs. commercial airliners?" Tags="&lt;military&gt;&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13094" PostTypeId="1" AcceptedAnswerId="13097" CreationDate="2015-03-06T16:45:15.823" Score="33" ViewCount="4489" Body="&lt;p&gt;This SFF.SE question: &lt;a href=&quot;https://scifi.stackexchange.com/questions/83209/why-did-red-squadron-give-their-call-signs-in-random-order&quot;&gt;&quot; Why did Red Squadron give their call signs in random order? &quot;&lt;/a&gt; raises a good point: for some reason, the &quot;Standing by&quot; responses Red Squadron pilots give before attacking the Death Star in &lt;em&gt;Star Wars Episode IV: A New Hope&lt;/em&gt; are out of order:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Red Leader: All wings report in.&lt;br&gt;&#xA;  Red Ten: Red Ten standing by.&lt;br&gt;&#xA;  Red Seven: Red Seven standing by.&lt;br&gt;&#xA;  Biggs Darklighter: Red Three standing by.&lt;br&gt;&#xA;  Porkins: Red Six standing by.&lt;br&gt;&#xA;  Red Nine: Red Nine standing by.&lt;br&gt;&#xA;  Wedge Antilles: Red Two standing by.&lt;br&gt;&#xA;  Red Eleven: Red Eleven standing by.&lt;br&gt;&#xA;  Luke Skywalker: Red Five standing by.&lt;br&gt;&#xA;  Red Leader: Lock S-foils in attack position.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(to top off the mis-ordering, Red Eight and Red Four never respond).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was of course answered in-Star-Wars-Universe, but I'd like a perspective of real aviation experts on this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is this protocol (all fighters in a group should report in by their call signs) based on something real fighter pilots would do (either WWII era pilots - since Star Wars fighter combat was famously based by Lucas on WWII - or 1970s era).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the main purpose of such a protocol? Communications check? Verifying who's flying? Verifying if someone has an issue? Team morale?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In light of #2, does the real life protocol have a specific order of responses, or is it as &quot;whoever responds whenever&quot; as in the Star Wars example?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7541" LastEditorUserId="-1" LastEditDate="2017-04-13T12:43:39.120" LastActivityDate="2017-10-20T20:58:35.840" Title="Is the &quot;Red two standing by&quot; dialog in Star Wars: A New Hope sensible for real fighter pilots?" Tags="&lt;military&gt;&lt;radio-communications&gt;&lt;call-sign&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13095" PostTypeId="1" CreationDate="2015-03-06T17:06:41.257" Score="1" ViewCount="73" Body="&lt;p&gt;Modern Boeing and Airbus aircraft employ a suction system for the lavatory on board. How is this suction system powered? By utilizing an on board suction pump or natural pressure and velocity difference from outside the aircraft during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to find out would be to try a flush while plane is on a taxiway, but access to the lavatory during that period is not allowed.&lt;/p&gt;&#xA;" OwnerUserId="7542" LastEditorUserId="167" LastEditDate="2015-03-06T17:15:24.397" LastActivityDate="2015-03-06T17:15:24.397" Title="Do commercial lavatory suction systems create pressure mechanically or naturally?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-03-06T19:37:56.253" ContentLicense="CC BY-SA 3.0" />
  <row Id="13096" PostTypeId="1" AcceptedAnswerId="13109" CreationDate="2015-03-06T18:34:08.517" Score="15" ViewCount="6285" Body="&lt;p&gt;And which is better for a scramjet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is a 2D inlet basically a &quot;2D cone&quot;? Similar to how an aerospike engine is made &quot;2D&quot; in the linear aerospike?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's &lt;em&gt;inside&lt;/em&gt; the cone/spike? Or is it just hollow?&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorDisplayName="user12485" LastEditDate="2015-12-21T17:50:45.363" LastActivityDate="2020-08-10T19:31:44.133" Title="What are the merits of an inlet cone/spike/centerbody vs. a 2D inlet?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;supersonic&gt;&lt;inlet&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13097" PostTypeId="2" ParentId="13094" CreationDate="2015-03-06T18:35:48.657" Score="29" Body="&lt;p&gt;Tactical call signs are typically given in the format &quot;word&quot; &quot;number&quot; - &quot;number&quot;.  For example, Camel 1-1.  In this example Camel 1-1 is the lead Camel in the Camel flight.  As you may have guessed, instructions are always acknowledged in order.  This helps the lead aircraft determine who may not have received the instruction (and some instructions are extremely time critical), or worse, in the event of an accident, determine (by lack of communication) who might be involved.  If someone does miss a comm, then typically the flight waits a few seconds and the next guy in line makes his radio call with the lead noting the person that was skipped.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tactical call signs change with each flight, and may or may not have any real significance to the event being flown.  Funny ones are usually best; i.e., Camel works really well if you want to Alpha check a point called &quot;Toe&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a typical scenario: While practicing a 2v1 in the MOA (military operating area), Camel 1-2 gets a HYD caution, and has to stop the fight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Camel 1-2 initiates with, &quot;Camels knock it off, knock it off.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next the flight reports back in order:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Camel 1-1, knock it off.&quot; &lt;/li&gt;&#xA;&lt;li&gt;&quot;Camel 1-2, knock it off.&quot; (Even though Camel 1-2 initiated it, he still reports in order)&lt;/li&gt;&#xA;&lt;li&gt;&quot;Camel 1-3, knock it off.&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I would say that Lucas came pretty close to replicating the actual sequence.  Sure, they're out of order and they're missing the &quot;# - #&quot; format, but its a decent attempt for Hollywood.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="11215" LastEditDate="2017-10-20T20:58:35.840" LastActivityDate="2017-10-20T20:58:35.840" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13098" PostTypeId="1" AcceptedAnswerId="13105" CreationDate="2015-03-06T22:33:15.733" Score="12" ViewCount="4056" Body="&lt;p&gt;In the &lt;a href=&quot;http://avherald.com/h?article=482b659f&quot;&gt;recent runway excursion at LGA&lt;/a&gt;, visibility was bad, and an airport ops vehicle called the tower to inform them of the excursion and that runway 13 was closed, and then that the airport was closed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower is in charge during normal operations. Who has the authority to close a runway/airport? Is this codified somewhere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This also applies on a smaller scale, as I've heard of such things as chunks of taxiway pavement going missing.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-03-09T20:57:34.397" Title="Who has authority to close a runway/airport?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;airport&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13099" PostTypeId="2" ParentId="13098" CreationDate="2015-03-06T23:40:29.003" Score="-3" Body="&lt;p&gt;This is kind of a gray area, but there is a procedure...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically, the way a runway is closed is that the airport or airfield operator notifies, in writing, the FAA thirty days ahead of time that a publicly-accessible runway will be closed. The FAA then issues a NOTAM about the closure and the airport puts big X's on the runway at either end. The runway is then closed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of accident, you obviously cannot &quot;close&quot; a runway this way. The best you can do is warn pilots off it. Since there is no way to &quot;close&quot; a runway on a short-term basis, what happens is that they &quot;close&quot; the entire airport, which is what happened at La Guardia. There is no NOTAM or forewarning during the initial response, so small aircraft can potentially still arrive and they have to be warned off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, a lot of police and firemen do not understand this, so they try to &quot;close&quot; a runway just by ordering the tower to close it. Often, they do not even do this; they just rush onto the tarmac without even waiting to get permission or calling anyone. Obviously this creates incredibly dangerous situations. The tower (if there is one) reacts to this irregular action by notifying ATC and making constant do-not-land-here warnings on the common channel(s). If there is no tower, &lt;em&gt;hopefully&lt;/em&gt; there are people on the ground with radios who do the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just as an example of how dangerous this can become: once I was at an airfield with no tower and an aircraft landed short in the trees, getting hung up in some branches. A bunch of state police cars and fire engines &lt;strong&gt;literally drove down the runway&lt;/strong&gt; to get to him like it was a road or something. The danger here is that many smaller aircraft or ultralights (etc) may not have (working) radios or may be on the wrong frequency so they have no idea what is happening. They could have just landed on one of the cop cars and blown up killing everybody. After it happened we called the police and told them how to drive on side of the airfield (not down the runway !!!) and provided them with emergency route maps, but at a certain level it is whistling in the dark, because most emergency personnel do not read these materials.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-07T05:45:04.230" LastActivityDate="2015-03-07T05:45:04.230" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13100" PostTypeId="1" CreationDate="2015-03-06T23:41:25.010" Score="8" ViewCount="2101" Body="&lt;p&gt;When cleared for a visual approach, do airline pilots still use the localiser/glideslope or GPS or even the autopilot, or is it strictly a &quot;visual&quot; approach?&lt;/p&gt;&#xA;" OwnerUserId="7547" LastEditorUserId="65" LastEditDate="2015-03-09T16:06:20.123" LastActivityDate="2015-03-09T16:06:20.123" Title="Can a pilot use ILS when cleared for a visual approach?" Tags="&lt;landing&gt;&lt;ils&gt;&lt;visual-approaches&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13103" PostTypeId="2" ParentId="13100" CreationDate="2015-03-07T01:18:49.743" Score="7" Body="&lt;p&gt;Yes, the localiser, ILS glideslope, and/or GPS-generated glidepath are still used as a reference during the visual approach. Sometimes the visual glideslope indicators (like VASI or PAPI) are either inoperative or not available. (Interestingly, the visual indicators and instrument-generated glidepaths are sometimes not coincident.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots sometimes choose to leave the autopilot engaged during such an approach. Some Charted Visual Flight Procedures (like the FMS Bridge Visual 28R at SFO) lend themselves to leaving the autopilot engaged for almost the entire approach. In addition, some operators may stipulate that autopilot use is mandatory.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2015-03-07T01:24:39.657" LastActivityDate="2015-03-07T01:24:39.657" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13104" PostTypeId="1" AcceptedAnswerId="13124" CreationDate="2015-03-07T02:15:56.737" Score="6" ViewCount="1591" Body="&lt;p&gt;I left SLC (Salt Lake City) this morning heading to MCO (Orlando). On previous flights, I remember takeoff similar to other airports. We got in the air, gained altitude, and moved to our heading and left. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This time though, we seemed to circle for a while, gaining altitude. I initially assumed it was to gain enough altitude to clear the surrounding mountain. I ruled out equipment problems because we kept climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots who have experience with SLC, is there a certain runway that needs this altitude gain due to the terrain? Would there be another possible reason this happened?&lt;/p&gt;&#xA;" OwnerUserId="7549" LastEditorUserId="7549" LastEditDate="2015-03-07T02:20:57.007" LastActivityDate="2015-03-08T16:41:38.603" Title="Why circle an airport after takeoff? (SLC particularly)" Tags="&lt;airport&gt;&lt;takeoff&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13105" PostTypeId="2" ParentId="13098" CreationDate="2015-03-07T03:50:51.737" Score="8" Body="&lt;p&gt;Generally two groups have authority to close a runway (or airport) for an incident/emergency, and if either says it's closed, it's closed:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The airport owner/operator/management.&lt;/strong&gt;&lt;br&gt;&#xA;It's their facility, so if they say it's closed, it's closed.&lt;br&gt;&#xA;&lt;em&gt;Specifically&lt;/em&gt; it's the persons authorized to issue NOTAMs for the airport who can close a runway (by issuing the NOTAM saying it's closed), but the chain of command for making this decision may vary from airport to airport.&lt;br&gt;&#xA;Runways may also be closed by airport administration without issuing a NOTAM (this happens frequently at Brookhaven airport (KHWV) - &lt;a href=&quot;https://aviation.stackexchange.com/questions/2241/why-is-a-large-flashing-x-placed-on-a-closed-runway-at-reagan-national-airport&quot;&gt;&quot;Closed Runway&quot; X's&lt;/a&gt; will be put out on the crosswind runway when the banner tow operators are set up for pick-up/release on that runway). Often there's a blanket NOTAM about &quot;banner tow ops&quot; or similar that sort-of covers this situation (basically &quot;Expect strange things to be happening because the banner tow people are doing...whatever it is they do&quot;.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The control tower (if one exists).&lt;/strong&gt;&lt;br&gt;&#xA;Whether or not they have the &lt;em&gt;administrative&lt;/em&gt; authority to &quot;close&quot; a runway, they certainly have the &lt;strong&gt;&lt;em&gt;practical&lt;/em&gt;&lt;/strong&gt; authority to do so by denying anyone clearance to take off/land from it or to enter it, and by issuing NOTAMs indicating that a runway is closed/unusable for some reason.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;At an airport like LaGuardia where you have both an FAA Control Tower and a robust airport operations/management group (The Port Authority of New York &amp;amp; New Jersey) a Memorandum of Understanding (MOU) or similar agreement is likely in place to ensure that everyone knows who is authorized to do what when, but in cases like this where an aircraft has a runway excursion the course of action is pretty obvious and nobody is going to want aircraft to be moving around on the ground until the situation is under control and safety can be assured.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-07T04:01:28.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13107" PostTypeId="1" AcceptedAnswerId="13131" CreationDate="2015-03-07T12:27:33.207" Score="14" ViewCount="1190" Body="&lt;p&gt;We all know air traffic controllers have one of the hardest, most stressful jobs on the planet... day after day they handle thousands of aircraft with the cool of a seasoned gunfighter and the surgical precision of a Jenga-playing robot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what about when there's no aircraft around? Perhaps it's freezing rain and there no chance of an aircraft landing. Or perhaps the (extremely) high volume of flight training at a particular field suddenly drops to nearly zero over spring break. Or maybe fate and luck just got together and no one wants to go to that airport today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What do controllers do when there's no aircraft in their area, and especially what do they do when there's not likely to be any aircraft for an extended period (1+ hours)&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-03-09T16:15:49.190" Title="What do air traffic controllers do on a slow day?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13108" PostTypeId="2" ParentId="13098" CreationDate="2015-03-07T12:47:12.147" Score="4" Body="&lt;p&gt;In addition to the categories listed above, &lt;em&gt;pilots&lt;/em&gt; have the authority to close a runway. A braking action &lt;strong&gt;nil&lt;/strong&gt; report will automatically close that runway until the airport operator is satisfied that the condition no longer exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/airports/eastern/airport_safety/cert_bulletins/2009/03-Winter%20Ops%20AC%20Change.pdf&quot; rel=&quot;nofollow&quot;&gt;Winter Ops AC Change&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="1696" LastEditDate="2015-03-09T20:57:34.397" LastActivityDate="2015-03-09T20:57:34.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13109" PostTypeId="2" ParentId="13096" CreationDate="2015-03-07T13:11:43.810" Score="26" Body="&lt;p&gt;Both are ways to create compression shocks in order to &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;compress and decelerate supersonic air&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h2&gt;Spike intakes&lt;/h2&gt;&#xA;&lt;p&gt;The central spike is characterized by:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;undisturbed flow,&lt;/li&gt;&#xA;&lt;li&gt;light weight and compactness, and&lt;/li&gt;&#xA;&lt;li&gt;easy adjustability to speed and mass flow at high flight speeds by translating the spike.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Its disadvantages are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;large loss of efficiency with angle of attack and sideslip,&lt;/li&gt;&#xA;&lt;li&gt;long internal ducting,&lt;/li&gt;&#xA;&lt;li&gt;limited space for radar installation, and&lt;/li&gt;&#xA;&lt;li&gt;limited mass flow at low speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Typical central spike intakes are those of the MiG-21 or the SR-71, as shown below. Note the variation in cone angle which helps to create additional, steeper shocks such that the flow is gradually decelerated over a sequence of shocks. The inside is filled with a radar system or hollow in case of the SR-71. At the height of the intake lip the SR-71 spike has a perforated wall to suck away the spike's boundary layer, and aft of that it contains the translation mechanism which shifts it back and forth to adjust the intake cross section and to adjust the shock position.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OQGHU.jpg&quot; alt=&quot;Intakes of the MiG-29 and the SR-71&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A variant of the central spike is a side intake with a compression half-cone, as used on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dassault_Mirage_III&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mirage III&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-104 Starfighter&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/BAC_TSR-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;TSR-2&lt;/a&gt;. Their location at the fuselage side helps to reduce the length of internal ducting and to reduce flow distortion due to sideslip. It also frees up space at the fuselage tip for a larger radar antenna. However, now the fuselage boundary layer has to be split off by a splitter plate to ensure equal flow energy over the whole intake cross section.&lt;/p&gt;&#xA;&lt;p&gt;The picture below shows the &lt;a href=&quot;http://en.wikipedia.org/wiki/English_Electric_Lightning&quot; rel=&quot;nofollow noreferrer&quot;&gt;English Electric Lightning&lt;/a&gt; with its central spike intake feeding two Rolls-Royce Avon engines, and the side intake of the TSR-2. Note the additional intake doors aft of the intake lip of the TSR-2 which were needed to increase mass flow at low speed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oLsB8.jpg&quot; alt=&quot;BAC Lightning accompanying the TSR-2 prototype during flight testing&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-111&lt;/a&gt; has a quarter-circle spike intake. Here, the wing root also helps to direct the flow, so angle-of-attack variations produce less intake flow distortion. To suck away the intake boundary layer, the spike is perforated at the lengthwise position of the intake lips.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sDn6A.jpg&quot; alt=&quot;Sketch of the F-111 intake and picture of the F-111 in flight&quot; /&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Ramp intakes&lt;/h2&gt;&#xA;&lt;p&gt;What you call 2D-intakes are normally rectangular with an oblique shape. The forward edge is used to create an oblique shock which can be positioned to hit the rearward edge on the opposite side by shifting one or both edges up and down. This also changes the cross section of the intake, so adjustments for mass flow can be made over a wide range. An adjustable ramp aft of the forward edge allows to create more shocks with decreasing obliqueness, such that the flow is decelerated by a sequence of shocks. Typical ramp intakes are those of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Grumman_F-14_Tomcat&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-14&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-15&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;nofollow noreferrer&quot;&gt;Concorde&lt;/a&gt;. Their advantages are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adaptability over a wide range of flow conditions, angles of attack and mass flows, and&lt;/li&gt;&#xA;&lt;li&gt;tailoring of the shock system for optimum efficiency over a wide range of supersonic speeds.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Their disadvantage is a consequence of the wide adaptability:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High weight and complexity.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Note that the pressure in the intake is a multiple of outside pressure at supersonic speed, so the intake is actually a pressurized duct. A rectangular intake will need massive structural reinforcements to stay in shape while the cross section transitions to a round shape downstream.&lt;/p&gt;&#xA;&lt;p&gt;The drawing below shows the intake of the F-14 at different flow conditions. Note that the sharp intake lips require them to be exactly aligned with the local flow direction to avoid flow separation.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EDiyR.jpg&quot; alt=&quot;Cross sections of the F-14 intake at three different speeds&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;While a central spike intake is the best choice for flying at the design speed, the rectangular intake works better over a wide range of speeds. The shift in air combat doctrine from flying as fast as possible (1950s) to flying mostly subsonic with brief supersonic dashes (since the 1970s) is reflected in the choice of intake type.&lt;/p&gt;&#xA;&lt;h2&gt;Hypersonic intakes&lt;/h2&gt;&#xA;&lt;p&gt;When flying at Mach 5 and above, the obliqueness of the shock waves will need a very long intake, and effective designs use the lower side of the forward fuselage as part of the intake to create the necessary sequence of shocks for pressure recovery. Now the fuselage nose becomes the forward lip of the intake, and the body is shaped to create ever steeper shocks. Alternatively, the lower forward fuselage is shaped to work like a section of a spike. What looks like the actual intake is actually the rear intake lip, and the divergent section of the intake aft of the rear lip is reduced since the flow in the combustion area is still supersonic in order to keep temperatures manageable, making the engine a scramjet. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;This answer&lt;/a&gt; has more information on supersonic combustion.&lt;/p&gt;&#xA;&lt;p&gt;Note that this type of intake is optimized for one speed, and very little adjustment is possible. The pictures below show a NASA CFD study of the X-43A (left, &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/5/55/X-43A_%28Hyper_-_X%29_Mach_7_computational_fluid_dynamic_%28CFD%29.jpg/1280px-X-43A_%28Hyper_-_X%29_Mach_7_computational_fluid_dynamic_%28CFD%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) and the Russian Ajax project (right, &lt;a href=&quot;http://www.astronautix.com/graphics/a/ajax93.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). A scramjet can use both types of intake, and the fuselage design will determine which type it will be.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/g7Rje.png&quot; alt=&quot;CFD simulation of Hyper-X and test model of a Russian hypersonic project&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The rear fuselage now becomes the nozzle of the engine, because most of the expansion will happen after the flow leaves the enclosed part of the engine.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-08-10T19:31:44.133" LastActivityDate="2020-08-10T19:31:44.133" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="13110" PostTypeId="2" ParentId="13087" CreationDate="2015-03-07T13:16:27.540" Score="7" Body="&lt;p&gt;Indeed: climbing from FL240 to FL260 represents a smaller pressure drop than climbing from, say,  2000' to 4000'. The instrument is calibrated for this (it is mechanically built in such a way to represent this pressure drop in a non-linear way) and can properly represent the measured pressure into a ISA calibrated altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just bear in mind that since altimeters have a fixed error margin in hPa, that hPA error will signify a greater error margin in feet as you climb. Which is a good reason why most GA altimeters are certified only up to 20.000 feet or so depending on how much you wanna spend on them. It is also the reason why there is an increased vertical separation (2000' instead of 1000') for flights above FL280. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;eg. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=&amp;amp;r=PART&amp;amp;n=14y1.0.1.3.21#14:1.0.1.3.21.0.363.14.57&quot; rel=&quot;noreferrer&quot;&gt;Regulations&lt;/a&gt; for TSO'd altimeters allow up to 20 feet of error at altitudes up to 1000', but allow for 140 feet or so at FL250&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2015-03-07T14:35:30.240" LastActivityDate="2015-03-07T14:35:30.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13113" PostTypeId="1" CreationDate="2015-03-07T15:14:42.403" Score="0" ViewCount="624" Body="&lt;p&gt;Is there any FAA reference that recommends or specifically allows for the use of a coupled approach (such as autoland) when the pilot is specifically cleared for a visual approach?&lt;/p&gt;&#xA;" OwnerUserId="7550" LastEditorUserId="62" LastEditDate="2015-03-08T16:03:11.440" LastActivityDate="2015-03-08T16:24:57.970" Title="Is there any regulation that authorizes autopilot use when cleared for a visual approach?" Tags="&lt;faa-regulations&gt;&lt;landing&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-03-09T09:40:59.260" ContentLicense="CC BY-SA 3.0" />
  <row Id="13114" PostTypeId="1" AcceptedAnswerId="13122" CreationDate="2015-03-07T16:30:12.787" Score="15" ViewCount="5396" Body="&lt;p&gt;I've never understood this, why can't you just idle the engine and let it slow down?&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2020-02-19T15:51:15.007" Title="What causes a run-away propeller?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;piston-engine&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13116" PostTypeId="1" CreationDate="2015-03-08T00:25:21.110" Score="19" ViewCount="2270" Body="&lt;p&gt;Federal regulation CFR 252.3 notes that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air carriers shall prohibit smoking on all scheduled passenger&#xA;  flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Was this because of: 1) passenger safety concerns (the airplane may catch on fire from an unextinguished cigarette); 2) consumer demand (passengers demanded all-non-smoking flights); or, 3) for occupational safety concerns (the flight attendants were breathing in cigarette smoke all day)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've posted my own answer but am happy to be proven incorrect.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related questions:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;• &lt;a href=&quot;https://aviation.stackexchange.com/questions/2785/when-did-inflight-smoking-become-widely-prohibited&quot;&gt;When did inflight smoking become (widely) prohibited?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• &lt;a href=&quot;https://aviation.stackexchange.com/questions/613/is-it-legal-to-smoke-in-your-own-plane&quot;&gt;Is it legal to smoke in your own plane?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-06-27T04:03:14.193" Title="Was smoking banned because of passenger safety or occupational safety?" Tags="&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13117" PostTypeId="2" ParentId="13116" CreationDate="2015-03-08T00:27:53.467" Score="19" Body="&lt;p&gt;If you look at the part of the &lt;a href=&quot;https://www.law.cornell.edu/uscode/text/49/41706&quot;&gt;Federal code (49 U.S. Code § 41706)&lt;/a&gt; that actually instantiates this :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Smoking Prohibition in Interstate and Intrastate Air&#xA;  Transportation.— An individual may not smoke— (1) in an aircraft in&#xA;  scheduled passenger interstate or intrastate air transportation; or&#xA;  (2) in an aircraft in nonscheduled passenger interstate or intrastate&#xA;  air transportation, &lt;strong&gt;if a flight attendant is a required crewmember on&#xA;  the aircraft (as determined by the Administrator of the Federal&#xA;  Aviation Administration).&lt;/strong&gt; (b) Smoking Prohibition in Foreign Air&#xA;  Transportation.— The Secretary of Transportation shall require all air&#xA;  carriers and foreign air carriers to prohibit smoking— (1) in an&#xA;  aircraft in scheduled passenger foreign air transportation; and (2) in&#xA;  an aircraft in nonscheduled passenger foreign air transportation, &lt;strong&gt;if a&#xA;  flight attendant is a required crewmember on the aircraft (as&#xA;  determined by the Administrator or a foreign government).&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is the presence of a flight attendant that triggers the non-smoking requirement. Thus, one can safely assume that it is an occupational safety concern (sidestream smoke) that forced the regulation change.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastActivityDate="2015-03-08T00:27:53.467" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13118" PostTypeId="1" CreationDate="2015-03-08T06:38:35.280" Score="2" ViewCount="514" Body="&lt;p&gt;I have referred to standard author books and online tutorials but I am still quite confused about how the Stall and Throttle characteristics lead to Surge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt;  &lt;strong&gt;Why&lt;/strong&gt; and &lt;strong&gt;how&lt;/strong&gt; does the throttle characteristic affect the compressor performance because as far as i know, the next consecutive element in an engine after a Compressor is a Combustor, and the throttle comes at last,after combustor and turbine,  assuming throttle is same as nozzle (if not please correct me). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume i am talking about turbojet engines and Axial compressor, just to have a picture in mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2.&lt;/strong&gt; How does the throttle characteristic curves come out to be like that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And why does the mass flow decrease when we throttle the compressor?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3.&lt;/strong&gt; I am also unable to grasp the concept which causes the &lt;strong&gt;evil&lt;/strong&gt; fluctuations in the flow during surge, which leads to reverse flow and damage of the components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7py40.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Source:-&lt;/strong&gt; Hill Peterson- Thermodynamics of Propulsion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Someone please explain the concepts as much as possible.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="3029" LastEditDate="2015-03-08T07:02:16.540" LastActivityDate="2015-03-08T11:55:22.550" Title="What is qualitative relationship between surge line, stage characteristic and throttle characteristic?" Tags="&lt;aircraft-performance&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13119" PostTypeId="2" ParentId="13118" CreationDate="2015-03-08T09:45:35.163" Score="4" Body="&lt;p&gt;Since your question is divided in three parts, I do the same with my answer. First, however, we need to explain what the axes of the graph mean. The x-axis plots mass flow through the compressor, which is roughly equivalent to the tip speed of the compressor blades, and the y-axis shows the pressure ratio between entry and exit flow.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Throttle and compressor performance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The throttle regulates fuel flow, and this flow has to match the air flow. The limits are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If fuel flow is too high: The combustion will create too much heat, so the turbine will be damaged.&lt;/li&gt;&#xA;&lt;li&gt;If fuel flow is too low: Too little energy is added to sustain the current operating point. The engine will slow down.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If it is kept within those limits, the throttle will indirectly control the compressor speed and it's mass flow. More fuel flow will translate into higher turbine entry speeds, which will increase the torque produced by the turbine and speed it up. Since it is directly coupled with the compressor, it will see the same speed increase. This leads to higher mass flow and a lower fuel-to-air ratio in the combustor (relative to the state right after the throttle increase), such that a new equilibrium at a higher speed is established.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Throttle lines&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For every pressure ratio the compressor will have a matching mass flow, and both move up and down in parallel. This is shown by the dashed lines. Depending on the blockage of flow in the turbine and the engine nozzle, different lines are shown for different grades of blockage. The solid stage characteristic line shows the limits within which the compressor will run, and a higher flow resistance narrows the range of speeds that are possible. The limits are determined by:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lower limit: Here the compressor is run at the lowest possible speed for the given blockage, and the compressor blades run close to their maximum lift coefficient. When the blockage is increased, the flow over the compressor blades will stall and the pressure ratio will collapse.&lt;/li&gt;&#xA;&lt;li&gt;Upper limit: Here the compressor blades run at high speed and a low lift coefficient. Running them any faster will not create enough pressure rise per stage, and again the blocking cannot be overcome.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Surge&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Once the pressure rise per stage cannot be maintained (say, due to a stall of the flow over the compressor vanes), the high pressure air in the combustor will find it easier to escape at the front than to flow through the turbine and the nozzle. This leads to reverse flow and a sudden drop in combustor pressure, which in turn allows the compressor to reverse the flow and start pumping air back again. Now the pressure in the combustor rises again, until the whole process repeats.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-08T11:55:22.550" LastActivityDate="2015-03-08T11:55:22.550" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13120" PostTypeId="2" ParentId="13104" CreationDate="2015-03-08T11:30:28.290" Score="2" Body="&lt;p&gt;To avoid terrain or obstacles. Admittedly, I don't know specifically which runway I took off from, making it difficult to provide a definitive answer for this specific airport.&lt;/p&gt;&#xA;" OwnerUserId="7549" LastActivityDate="2015-03-08T11:30:28.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13122" PostTypeId="2" ParentId="13114" CreationDate="2015-03-08T15:42:52.563" Score="14" Body="&lt;p&gt;Often the overspeed is caused by the airflow forcing the propeller to move faster. It's like braking on the engine while going down a steep hill, even without touching the gas pedal you may speed up and redline the engine. Very problematic if you already overheated your brakes in a 18 wheeler.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a variable pitch prop you can feather it to reduce the effect of the airflow. Or just follow the procedures in the overspeed checklist for the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-03-08T15:42:52.563" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13123" PostTypeId="2" ParentId="13113" CreationDate="2015-03-08T16:24:57.970" Score="2" Body="&lt;p&gt;The general answer is no. A visual approach isn't considered an instrument approach &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/ATC/atc0704.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;according to ATC&lt;/a&gt; so there's no restriction - or direction, if you prefer - on how to fly one:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A visual approach is an ATC authorization for an aircraft on an IFR&#xA;  flight plan to proceed visually to the airport of intended landing; it&#xA;  is not an instrument approach procedure. Also, there is no missed&#xA;  approach segment. An aircraft unable to complete a visual approach&#xA;  must be handled as any go-around and appropriate separation must be&#xA;  provided.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And from &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0505.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;the AIM 5-5-11&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot must, at all times, have either the airport or the preceding&#xA;  aircraft in sight. After being cleared for a visual approach, proceed&#xA;  to the airport in a normal manner or follow the preceding aircraft.&#xA;  Remain clear of clouds while conducting a visual approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means that when you're cleared for a visual approach it's entirely up to you how you approach and land, providing that you follow the rules mentioned in the AIM and  - in the case of airline operations - whatever procedures are detailed in your &lt;a href=&quot;https://aviation.stackexchange.com/questions/1641/what-are-operations-specifications-opspecs&quot;&gt;operations specification&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you're asking about autoland specifically (not general autopilot use) then the FAA does have a few relevant comments in their &lt;a href=&quot;http://fsims.faa.gov/WDocs/8900.1/V04%20AC%20Equip%20&amp;amp;%20Auth/Chapter%2002/04_002_007.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;guidelines for CAT III operations&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Autoland or HUD to touchdown operations are required for all CAT III&#xA;  operations, and many operators use autoland or HUD for CAT II, CAT I,&#xA;  and visual flight rules (VFR) operations as well. Part 121, §&#xA;  121.579(c); part 125, § 125.329(d); and part 135, § 135.93(d) prohibit the use of autoland or HUD to touchdown in any operation unless the&#xA;  operator is specifically authorized via OpSpecs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Practice autoland or HUD to touchdown operations may be conducted at&#xA;  CAT I runways in CAT I or better weather conditions where the facility&#xA;  classification is unknown, because the flightcrew is monitoring system&#xA;  performance, visually verifying the position of the aircraft, and can&#xA;  determine whether to continue to a landing or execute a missed&#xA;  approach in CAT I or better weather conditions. Though it is not&#xA;  recommended, flightcrew monitoring and increased visibility also&#xA;  permits practice autoland or HUD to touchdown operations using an ILS&#xA;  classified as I/A, I/B, I/C, or I/T, provided the operation is&#xA;  performed in VFR conditions&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I understand that to mean that autolanding is allowed in visual conditions (provided it's authorized via OpSpecs) for training/practice purposes, and since they mention autolanding use even under VFR I don't see why it wouldn't be allowed on a visual approach.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-08T16:24:57.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13124" PostTypeId="2" ParentId="13104" CreationDate="2015-03-08T16:41:38.603" Score="6" Body="&lt;p&gt;I would assume it was to avoid terrain, traffic and/or the restricted airspace close to the airport, but there is at least one departure procedure from KSLC that calls for a climb in the hold. The &lt;a href=&quot;http://155.178.201.160/d-tpp/1503/00365SALTLAKE_C.PDF&quot;&gt;SALT LAKE TWO departure&lt;/a&gt; includes this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Continue climb in TCH VORTAC holding pattern (hold south, left turn,&#xA;  341° inbound)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And several other departure procedures call for climbing right or left turns; combined with a few ATC vectors that could easily give the impression of circling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might try looking for the actual radar track online if you search &lt;a href=&quot;http://flightaware.com/&quot;&gt;flightaware.com&lt;/a&gt; or a similar site for your flight. That would let you see what track you really flew.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-03-08T16:41:38.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13126" PostTypeId="2" ParentId="13107" CreationDate="2015-03-08T21:46:13.947" Score="2" Body="&lt;p&gt;In many parts of the world, air traffic control within each FIR is actually further sub-divided into sectors. These sectors can all have their own controllers, but if things are slow then the sectors can be combined together so that a single controller is now looking at an even bigger area. If this happens, they often just take longer breaks between working the position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So all that to say, just because they controllers are on shift doesn't mean they're actually working traffic the whole time. If things are slow for hours on end, they may only work 40 minutes and then get an hour off or something like that.&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2015-03-08T21:46:13.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13127" PostTypeId="1" CreationDate="2015-03-08T22:52:18.913" Score="4" ViewCount="666" Body="&lt;p&gt;I'm busy revising for a license conversion... Out of curiosity, does anyone know of a radio navigational aid that used the frequencies we call HF (2-25 MHz)?  &lt;/p&gt;&#xA;" OwnerUserId="7487" LastEditorUserId="62" LastEditDate="2015-03-09T14:35:11.410" LastActivityDate="2017-08-02T04:44:49.570" Title="Are there any air navigation uses for the HF frequencies?" Tags="&lt;navigation&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13128" PostTypeId="2" ParentId="13067" CreationDate="2015-03-08T23:27:47.023" Score="5" Body="&lt;p&gt;My experience from flying Commercial IFR in &lt;em&gt;Europe&lt;/em&gt; is that ATC &lt;em&gt;never&lt;/em&gt; proactively re-route around bad weather, but are however usually expedient handling requests from pilots (heading changes to circumnavigate), based on airborne weather radar data.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastActivityDate="2015-03-08T23:27:47.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13129" PostTypeId="1" AcceptedAnswerId="13130" CreationDate="2015-03-09T02:07:25.823" Score="8" ViewCount="3534" Body="&lt;p&gt;I am trying to solve a numerical problem related to determining take-off roll using a take-off distance graph. The parameters are Temp: 90F, Press. alt: 2000ft, wt: 2500lbs, headwind: 20 Knots. I got the following graph (solid red lines):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tjq0W.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions/clarifications are as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It looks like the first reference line is the &quot;density altitude&quot;, correct?&lt;/li&gt;&#xA;&lt;li&gt;Looks like the second section of the graph is a relationship between aircraft weight and take-off roll (where take-off roll distances are represented vertically on the second reference) at various density altitudes. This seems to make sense because for a certain weight, if I go up, meaning I intercept higher density altitudes, the take-off roll increases. &lt;/li&gt;&#xA;&lt;li&gt;It is not very clear to me the plotting of the diagonal lines. The way I understood it is that they go from the point of interception of the reference line to a point on the vertical weight line which is midway between the inclined curves intercepting that vertical weight line.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="173" LastEditorUserId="173" LastEditDate="2015-03-09T02:26:43.650" LastActivityDate="2015-03-09T16:18:45.287" Title="What are the meanings of various reference lines and sections in a take-off distance graph?" Tags="&lt;takeoff&gt;&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13130" PostTypeId="2" ParentId="13129" CreationDate="2015-03-09T07:50:22.883" Score="7" Body="&lt;p&gt;You need to read such graphs strictly from left to right. Each new panel adds the influence of another parameter, and when you are done, the result is corrected for altitude, take-off weight, wind and obstacle height. Except for the leftmost panel, the groups of lines only help you to find the correct slope and do not represent a certain altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You start with the outside air temperature. Pick what the instrument in your cockpit indicates, and go from the temperature axis straight up until you intercept the line which is closest to your given pressure altitude. This can be read directly from the altimeter if it is set correctly. You can try to interpolate between lines, but to be safe pick the next higher value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, move horizontally to the first reference line. From there, follow the slope of the lines until you intercept the x-position which corresponds to your aircraft's mass. If you start between two lines, you should move such that the relative vertical distance to the neighboring lines does not change. Note that the take-off mass is also a value you should know already if your preflight was done properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From that point, jump off horizontally until you intercept the next reference line. Depending on wind direction, follow either the dashed or the solid lines until you arrive at the x-position which corresponds to the wind component in runway direction. You will note that for headwind you will move slightly down, so headwind shortens the take-off distance. Makes sense, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last panel helps you to find both the take-off roll (obstacle height zero) and the take-off distance over a 50 ft obstacle. Here you can only extract the values at the x-positions 0 and 50 and interpolation will not work. The y-axis all the way on the right now will tell you the distances in feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reference lines show the values for the standard take-off at MTOW and calm wind. The examples given by the red lines are for two different situations:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Solid red line: OAT is 90°F, pressure altitude is 2000ft MSL, take-off mass is 2500lbs and with a headwind of 20kts the take-off roll is 500ft. At this point your speed should be 62kts (see table).  This is the result for your first question.&lt;/li&gt;&#xA;&lt;li&gt;Dashed red line: OAT is 15°C, pressure altitude is 6000ft MSL (rounded up from 5650ft), take-off mass is 2950lbs and with a headwind of 9kts your take-off roll is 1400ft and the distance needed to clear the 50ft obstacle at 1.3*stall speed is 2300ft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-09T16:18:45.287" LastActivityDate="2015-03-09T16:18:45.287" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13131" PostTypeId="2" ParentId="13107" CreationDate="2015-03-09T09:28:01.150" Score="11" Body="&lt;p&gt;The airspace around the world is divided into sectors within a &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_information_region&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Information Region&lt;/a&gt; (FIR) /Air Route Traffic Control Center (ARTCC) / &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_Control_Center&quot; rel=&quot;nofollow noreferrer&quot;&gt;Area Control Center&lt;/a&gt; (ACC), which range from very small and tight airspace pieces to larger combinations or enroute sectors. Enroute sectors will usually be larger than &lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_control_area&quot; rel=&quot;nofollow noreferrer&quot;&gt;Terminal Maneouvering Areas&lt;/a&gt; (TMA).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During peak-hours, these sectors will be handled by one controller responsible for each sector. If capacity and traffic flow permit, these sectors can be combined and two sectors will be handled by the same controller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a picture of the Paderborn Lower Sector, ranging from GND to FL135. This is usually a stand-alone sector which only covers approaches to Paderborn (EDLP) and Dortmund Airports (EDLW).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KToSz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: Own Work - Author: SentryRaven)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If traffic permits, the adjacent sector Hamm Lower from GND to FL115, handling arrivals and departures to Münster (EDDG), will be handed over to the controller responsible for Paderborn Lower. This can also be done vice-versa, where the Hamm Lower controller becomes responsible for the Paderborn Lower sector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SbRu6.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;(Image Source: Own Work - Author: SentryRaven)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TMA controllers not only handle IFR aircraft approaching or departing from airfields within their sector, but also any enroute traffic crossing the sector, VFR traffic requesting to cross airspaces which require prior permission and other tasks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/13126/572&quot;&gt;As Chatty already pointed out in his answer&lt;/a&gt;, controllers take breaks between working their sectors and sometimes often switch sectors during a shift. A controller working Paderborn Lower during the beginning of his shift can end up working Hamm Lower towards the end of his shift with adequate breaks in between their sessions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this related question:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/11754/572&quot;&gt;What is the maximum number of planes a controller can control?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-09T16:15:49.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13132" PostTypeId="1" AcceptedAnswerId="13134" CreationDate="2015-03-09T09:49:31.743" Score="49" ViewCount="44663" Body="&lt;p&gt;Various times, I have seen and felt myself that the plane always lands on the rear wheels, but not the front wheels. Why do the pilots land it on the rear wheels instead of the front? Does it have some advantage to it or is it a rule?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this required for all the planes (irrespective of size, type) to land only on the back wheels?&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="65" LastEditDate="2015-03-09T17:02:06.350" LastActivityDate="2018-01-21T15:06:50.997" Title="Why do planes always land on rear wheels instead of the nose wheels?" Tags="&lt;landing&gt;&lt;landing-gear&gt;" AnswerCount="11" CommentCount="13" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13133" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T09:56:14.547" Score="12" Body="&lt;p&gt;Not all, taildraggers will land on the front 2 wheels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because then the plane doesn't wheelbarrow off the runway. Have you ever tried running with a wheel barrow? The smallest deviation of forward will get expounded and before you know it the thing will be off to the side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing on the rear wheels will put the center of mass forward of the drag source so deviations left and right will self-correct. This plus differential braking will allow greater control over the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-03-09T09:56:14.547" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13134" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T10:05:10.983" Score="86" Body="&lt;p&gt;Aircraft land on the &lt;strong&gt;main&lt;/strong&gt; wheels. For aircraft with nose wheel it is the back ones, but for aircraft with tail wheel (also called “tail-draggers”) it is the front ones. In either case the main wheels are very close to centre of gravity and carry most of the aircraft's weight, the nose or tail wheel only carries a small fraction of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft must land on wheels that are close to the centre of gravity (longitudinally). If they were not, the force on the wheels would create a moment that would violently pitch the aircraft. Actually, tail-draggers tend to bounce on landing a bit because there still is some moment left and in case of tail-draggers it pitches the aircraft up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early planes were almost all tail-draggers, because that layout is more robust, handles unpaved runways better and has less drag when the gear is fixed. It however provides poor directional control especially once the tail lifts off the ground during take-off roll. Later most designs started to use nose-wheel, because it provides better directional control, is directionally stable, makes the floor level when the aircraft is standing so loading is easier and visibility during taxi is much better and with invention of retractable landing gear the drag didn't matter any more.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-04-28T19:01:31.260" LastActivityDate="2016-04-28T19:01:31.260" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13135" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T10:47:05.893" Score="18" Body="&lt;p&gt;In an approach an airplane is generally descending between 500 and 1000 feet per minute, that's a minimum of 8 feet per second. That may not sound like much but just hitting the ground at that rate of descent would lead to a big bounce and possibly damage the airplane.  It would certainly be uncomfortable for the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for an airplane to land softly, it must decrease its rate of descent, to do this the nose is raised in a maneuver called a &lt;a href=&quot;http://en.wikipedia.org/wiki/Landing_flare&quot;&gt;flare&lt;/a&gt;. A nose-up attitude will, in a tricycle configured airplane, bring the main (rear) wheels in contact with the ground first. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="65" LastEditDate="2015-03-09T17:04:22.297" LastActivityDate="2015-03-09T17:04:22.297" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13136" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T14:36:11.057" Score="32" Body="&lt;p&gt;Jan Hudec already &lt;a href=&quot;https://aviation.stackexchange.com/a/13134/755&quot;&gt;gave an excellent description&lt;/a&gt; of why the gear configurations are designed as they are. Another important thing to note, though, is that because aircraft are designed to land on their main gear, the other gear (nose gear in tricycle configurations or tail wheel in tail draggers) is &lt;em&gt;not designed to be able to take the force of a landing.&lt;/em&gt; Landing on the nose gear in an airliner will most likely cause the nose gear to collapse, leaving you in a situation like &lt;a href=&quot;http://en.wikipedia.org/wiki/Southwest_Airlines#Incidents_and_accidents&quot; rel=&quot;noreferrer&quot;&gt;Southwest Flight 345&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TYCd6.jpg&quot; alt=&quot;Southwest 345&quot;&gt;&#xA;Image Source: &lt;a href=&quot;http://www.nydailynews.com/new-york/queens/southwest-pilot-fired-laguardia-crash-article-1.1474479&quot; rel=&quot;noreferrer&quot;&gt;New York Daily News&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the passengers on that flight recorded the landing and &lt;a href=&quot;https://www.youtube.com/watch?v=bwYmMG61VDk&quot; rel=&quot;noreferrer&quot;&gt;posted it on YouTube&lt;/a&gt;. While there were only a few minor injuries (mainly from using the slide at such a high angle, if I remember correctly,) the aircraft received such substantial damage that it was written off. Obviously, that is not a desirable outcome, so airlines usually prefer their pilots to land on the main gear instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, when we talk about a tail dragger, we're talking about planes with a landing gear configuration like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OUOBM.jpg&quot; alt=&quot;DC-3&quot;&gt;&lt;br&gt;&#xA;Douglas DC-3. Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Douglas_DC-3#mediaviewer/File:Douglas_DC-3_Aigle_Azur_Palas_Jet_1953.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas tricycle landing gear refers to the configuration you're probably used to seeing that looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fmi1q.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;br&gt;&#xA;Boeing 737. Image Source: &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737#mediaviewer/File:Southwest_Airlines_Boeing_737-7H4_N231WN.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-09T14:36:11.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13137" PostTypeId="1" CreationDate="2015-03-09T14:44:01.203" Score="7" ViewCount="7417" Body="&lt;p&gt;There are two vertical bars beyond Vne labelled: &lt;code&gt;@800#-Vg = 150MPH&lt;/code&gt; and &lt;code&gt;@840#-Vg = 147MPH&lt;/code&gt;. These lines represent Vg at two different weights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you tell me what  Vg is, where it's officially defined, and how it's calculated?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TRU9i.jpg&quot; alt=&quot;vg diagram&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-03-09T18:44:57.330" Title="What is Vg in this VG diagram?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13138" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T14:51:00.850" Score="20" Body="&lt;p&gt;One quick comment regarding the previous discussion on tailwheel aircraft. Taildraggers actually have two landing techniques at their disposal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one most people envision, where the aircraft touches down on the mains before gently settling the tail down, is called a &lt;strong&gt;wheel landing&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is, however, also the &lt;strong&gt;three-point landing&lt;/strong&gt;, where the goal is to touch down with all three wheels at the same time and is usually the first landing technique taught, especially to pilots transitioning from tricycle gear aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The technique used on each landing is chosen based on a number of factors, among which:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landing type (e.g. short-field vs. cross-wind)&lt;/li&gt;&#xA;&lt;li&gt;Aircraft type (some aircraft are just plain more difficult to land or may be entirely unsuited for one technique versus the other)&lt;/li&gt;&#xA;&lt;li&gt;Pilot currency (with the exception of heavy wind conditions, I find three-points easier to &quot;grease&quot; when out of practice)&lt;/li&gt;&#xA;&lt;li&gt;Runway conditions (pavement is much less forgiving then grass of sloppy rudder control; by the same token, three-points can offer better debris clearance for the propeller on rough fields)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you want to learn more about aircraft and flying, I would encourage to look up FAA resources (especially the FAA Airplane Flying Handbook), as well as the trove of information on AOPA's website. &lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="65" LastEditDate="2015-03-09T17:07:06.210" LastActivityDate="2015-03-09T17:07:06.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13139" PostTypeId="2" ParentId="12915" CreationDate="2015-03-09T16:14:32.967" Score="21" Body="&lt;p&gt;The answer to this is, in part to do with corporate culture and part aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The corporate culture and history part is that Boeing have always built their noses that way and senior engineers have a tendency to return to designs they have used successfully before. If you look at the nose of a 747 and the nose of a B-17 you'll see some distinctive similarities that follow through all the major Boeing aircraft. This isn't surprising as lead designer of the 747, Joe Sutter, started working for Boeing on the 707 project under the direction of the engineers that designed the early flying forts.&#xA;Airbus is a newer company with a different corporate culture. They tend to embrace new design techniques like CFD computer modelling to a greater extent and this leads to slightly more efficient but less aesthetically pleasing nose and wing designs.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The science side is related to the speed that modern airliners travel at (around 0.85mach). At these speeds aircraft begin to encounter a phenomenon called 'Wave Drag' which is the incremental build-up of compressive shockwaves along the wings and fuselage as the aircraft approaches the speed of sound. The effect of wave drag is to drastically increase the overall drag affecting the aircraft, increasing the power output required from the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several methods of combating wave drag, the first of these is the swept wing that has been a feature of trans and supersonic aircraft since WW2. The optimum angle of wing sweep is determined by the cruising speed of the aircraft. A more recent innovation is the Transonic or 'Whitcomb' Area Rule which states that: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Two airplanes with the same longitudinal cross-sectional area distribution have the same wave drag, independent of how the area is distributed laterally&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wave Drag can be reduced by attempting to match the cross sectional proportions of an aircraft as closely as possible to those of a Sears-Haack body (an aerodynamically perfect shape for supersonic flight) This is why Airbus planes have blunter nose. it is also why there are strange bulges under the wing roots of the A380. they are both attempts to make the planes cross-section conform to a Sears-Haack body more closely.&lt;/p&gt;&#xA;" OwnerUserId="7571" LastEditorUserId="11659" LastEditDate="2020-05-04T08:06:39.270" LastActivityDate="2020-05-04T08:06:39.270" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="13140" PostTypeId="2" ParentId="13137" CreationDate="2015-03-09T16:36:47.120" Score="6" Body="&lt;p&gt;It is the maximum speed in gusty weather. Aircraft designers and certification authorities make assumptions about the maximum vertical gust an aircraft will encounter and design the strength of the wing spar for it. Here 24 feet per second are assumed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the mass of all parts not creating lift (fuselage, vertical tail, pilots, equipment ...) the load on the wing spar varies with the aircraft mass. For that reason, lighter aircraft can afford to enter a gust at a slightly higher speed. Here, the 800 lbs glider may fly up to 150 MPH, while the 40 lbs heavier glider should stay below 147 MPH to suffer the same wing spar bending loads when flying into this 24 fps gust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying faster means flying at a higher dynamic pressure and at a lower angle of attack. Entering a gust will increase the angle of attack by the ratio between gust speed and flight speed. Since dynamic pressure is proportional to the square of flight speed, a linear wing lift increase due to higher flight speed will remain when entering a vertical gust. Also, at lower speed the angle of attack might be high enough that the angle of attack increase due to the gust will stall the wing, putting a natural limit on the load increase. Flying faster will remove this load limitation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum flight speed in gusty weather v$_g$ is a limit speed just like v$_{NE}$, but applies only in specific weather conditions (admittedly those which are most suitable for glider flying). While v$_{NE}$ might be determined by a minimum flutter margin, a formula in the certification requirements or structural loads in maneuvers, v$_g$ is determined by the maximum load factor the aircraft can tolerate.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-09T18:44:57.330" LastActivityDate="2015-03-09T18:44:57.330" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13141" PostTypeId="2" ParentId="12830" CreationDate="2015-03-09T17:34:49.560" Score="4" Body="&lt;p&gt;The only formal classification of door types that I could find is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c3e5e64205841639a4efcd8ef5fad806&amp;amp;node=se14.1.25_1807&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 25.807&lt;/a&gt;, which specifies the emergency exit requirements for transport category aircraft. It defines Type I-IV, Type A-C, ventral and tailcone exits. The doors you usually enter and leave the aircraft through are probably type I or A:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Type I. This type is a floor-level exit with a rectangular opening of&#xA;not less than 24 inches wide by 48 inches high, with corner radii not&#xA;greater than eight inches.&lt;/p&gt;&#xA;&lt;p&gt;Type A. This type is a floor-level exit with a rectangular opening of&#xA;not less than 42 inches wide by 72 inches high, with corner radii not&#xA;greater than seven inches.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;These definitions are quite generic, but Transport Canada has a handy list of &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp12296-schedulea-section2-5545.htm#section4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Exit Profiles&lt;/a&gt; that gives specific details (often including the type) for many common aircraft. It says this for the 767 main doors:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;B-767-200/300ER (Doors 1L/R FWD, 2L/R AFT)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Note&lt;/strong&gt;: Some models equipped with 2 additional type 1 exits L/R just forward of wing.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;H - 1.88 m (6 ft 2 in) W - 1.07 m (3 ft 6 in); Type A&lt;/li&gt;&#xA;&lt;li&gt;Equivalent force required to move door control handle from closed/locked position to open position (Normal and Emergency): 12 kg&#xA;(26 lbs).&lt;/li&gt;&#xA;&lt;li&gt;Approximate force required to open a door (lift upward) from unlocked to open: 18 kg (40lbs).&lt;/li&gt;&#xA;&lt;li&gt;&amp;quot;Counterbalance&amp;quot; opening design.&lt;/li&gt;&#xA;&lt;li&gt;Inward/upward opening doors.&lt;/li&gt;&#xA;&lt;li&gt;Manually operated except some models equipped with electrical (normal operation) opening/closing option (FWD Entry Door).&lt;/li&gt;&#xA;&lt;li&gt;Unique arming/disarming mechanism (lever, indicators).&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Release button must be depressed and held to move arming lever to &amp;quot;Slide Armed&amp;quot; mode.&lt;/li&gt;&#xA;&lt;li&gt;Yellow plastic &amp;quot;Emergency Use Only&amp;quot; (bendable) flag moves upward in front of Door Control Handle when slide is in armed mode.&lt;/li&gt;&#xA;&lt;li&gt;Double channel slides.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;Upward rotating Door Control Handle.&lt;/li&gt;&#xA;&lt;li&gt;&amp;quot;Uplatch&amp;quot; mechanism holds door in open position. Button must be depressed while door is lowered initial few inches, to release.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;You can see from that list that the details can vary a lot, even if the basic designs are very similar.&lt;/p&gt;&#xA;&lt;p&gt;Coming up with pros and cons for every variant would be tough (especially for me, since I know nothing about it!), but obviously some aircraft are larger than others and that will limit how much space is available for the door mechanism. There are also operational considerations: aircraft that frequently operate out of smaller airports without &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_bridge&quot; rel=&quot;nofollow noreferrer&quot;&gt;jet bridges&lt;/a&gt; may need to have &lt;a href=&quot;http://en.wikipedia.org/wiki/Airstair&quot; rel=&quot;nofollow noreferrer&quot;&gt;airstairs&lt;/a&gt;, which are usually built into the doors.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-09T17:34:49.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13144" PostTypeId="2" ParentId="13132" CreationDate="2015-03-09T22:34:43.773" Score="-1" Body="&lt;p&gt;While there is certainly a lot of truth in the above answers they all sort of treat the question in a fashion similar to: &quot;Why does water freeze at the top and work down? Because otherwise fish would freeze.&quot; While there are a number of reasons why landing on the back wheels works better the single most important one is that when airplanes land their nose is higher than their tail so their back wheels are closer to the ground. The reasons for this is because as planes slow down their wings generate less lift. They have to do something to make their wings generate enough lift despite the airspeed reduction so as to keep flying else a sub-optimal condition involving bent metal and maybe fireballs will occur. They do this by pointing nose up which increases the wings' angle of attack and by changing the shape of the wing (flaps and slats) to make the wings generate greater lift at the expense of introducing more drag. By the time that they get close to the ground they have slowed as much as they dare which means that the speed alternatives are being used as much as possible. That means that the aircraft is leaning back as much as it safely can and flaps are fully extended. Right at the point that a safe landing is guaranteed then the greater danger to the aircraft's safety shifts from falling out of the sky to hitting the ground at too fast a speed so the pilot does things to dump speed. That means leaning the plane back just enough to increase air resistance but not enough to make it bob up in the air. A good pilot does this just a very few feet above the ground and adjusts things so that the plane levels out for a few brief seconds as the speed bleeds off. A not so good pilot briefly gains altitude and then the plane falls out of the air from 10 or 20 feet up and the passengers get to experience three or four very short flights before the plane finally settles down on the ground. All of this puts their back wheels closer to the ground which means that's where the rubber meets the road.&lt;/p&gt;&#xA;" OwnerUserId="7574" LastActivityDate="2015-03-09T22:34:43.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13145" PostTypeId="2" ParentId="13132" CreationDate="2015-03-10T00:17:51.293" Score="1" Body="&lt;p&gt;Your &quot;rear wheels first&quot; observation pertains to aircraft with &quot;tricycle&quot; landing gear. For various reasons, the landing gear of such aircraft is configured so that they sit more-or-less level on the ground (when parked or taxiing). Such an aircraft usually cannot take off or land in such a level attitude. This is because the wings won't generate enough lift unless the aircraft is at or near cruising airspeed. To minimize wear and tear, danger, and runway length, takeoff and landing is performed at the lowest possible speed, allowing for a safe margin above stall. To fly at such speeds, the wing needs a high angle of attack, which means the aircraft has to be pitched into a nose-high attitude. To make the landing a positive transition, aircraft &quot;flare&quot;; essentially pitching up higher and higher and slowing down more and more while just above the runway until the wing essentially &quot;stalls&quot; - loses lift. At this point, the aircraft settles onto the runway at the slowest possible speed and should stay in contact with the runway (not &quot;bounce&quot; or &quot;balloon&quot; up). All this amounts to touching down on the main gear first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is certainly possible to touch down on the nosewheel first - a term called &quot;wheelbarrowing&quot;. This is very dangerous. Firstly, it could only occur if the approach was flown too fast - more speed means more forces and things going wrong more quickly. Second, the aircraft is touching down on a point ahead of the center of gravity. The slightest sideways motion will create a lateral moment that could (and probably would) spin the plane around into a crash.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-03-10T00:17:51.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13146" PostTypeId="2" ParentId="13127" CreationDate="2015-03-10T00:29:23.867" Score="7" Body="&lt;p&gt;Current airborne radionavigation systems use MF (NDB), VHF (VOR/LOC, marker beacons), UHF (G/S), and L-band microwave  (GPS/GNSS, DME) frequencies.  (MLS operates in the C-band, and airborne radar in the X-band, but those are niche applications.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, the only system that used HF was the UK &lt;a href=&quot;https://en.wikipedia.org/wiki/Gee_%28navigation%29&quot; rel=&quot;noreferrer&quot;&gt;Gee&lt;/a&gt; system.  &lt;a href=&quot;https://en.wikipedia.org/wiki/LORAN&quot; rel=&quot;noreferrer&quot;&gt;LORAN-A&lt;/a&gt; had options for the use of HF frequencies, but these were never used, as MF operation just below the 2 MHz mark gave much more consistent results in both reception range and performance, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Loran-C&quot; rel=&quot;noreferrer&quot;&gt;LORAN-C&lt;/a&gt; migrated into the LF band at 180kHz, partially to avoid the difficulties of being co-located with the amateur radio 160m band.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Decca_Navigator_System&quot; rel=&quot;noreferrer&quot;&gt;Decca&lt;/a&gt; also used LF frequencies, and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Omega_(navigation_system)&quot; rel=&quot;noreferrer&quot;&gt;Omega&lt;/a&gt; system operated at VLF to provide (imprecise) global coverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, the &lt;a href=&quot;http://www.fcc.gov/oet/spectrum/table/fcctable.pdf&quot; rel=&quot;noreferrer&quot;&gt;FCC frequency table&lt;/a&gt; shows no allocations for the Radionavigation service anywhere from 2 to 30MHz, in &lt;em&gt;any&lt;/em&gt; ITU region.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-03-10T00:29:23.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13147" PostTypeId="2" ParentId="12205" CreationDate="2015-03-10T00:34:00.820" Score="3" Body="&lt;p&gt;If you do it often enough, it becomes a habit. It then feels wrong to not run the checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only problem with all that repetition is that while you ran through all the items, you didn't actually &lt;strong&gt;do&lt;/strong&gt; the thing which needed to be done on that occasion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Case in point: &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Florida_Flight_90&quot; rel=&quot;nofollow&quot;&gt;Air Florida Flight 90&lt;/a&gt;. One of the checklist items was engine anti-ice. The crew of the accident flight was accustomed to flying in warm weather conditions. In such conditions, engine anti-ice is not necessary or appropriate, so the checklist action/response would always be &quot;off&quot;. For the flight in question, engine anti-ice would have been at least a wise precaution if not critical to a safe takeoff, yet the habit prevailed and the takeoff was attempted without engine anti-ice. Without anti-ice, sensors were likely blocked with ice, causing incorrect readings on gauges indicating engine performance. This led the crew to apply insufficient power to accomplish the takeoff. &lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-03-10T00:34:00.820" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13148" PostTypeId="2" ParentId="12915" CreationDate="2015-03-10T07:22:31.073" Score="13" Body="&lt;p&gt;Airbus and Boeing are not the only airplane manufacturers who see the nose shape as something to sharpen their brand. Look at the &lt;a href=&quot;http://www.alexander-schleicher.de&quot; rel=&quot;noreferrer&quot;&gt;Schleicher&lt;/a&gt; gliders (the left picture shows an ASW-20) and compare their pointed nose to those of &lt;a href=&quot;http://en.wikipedia.org/wiki/Schempp-Hirth&quot; rel=&quot;noreferrer&quot;&gt;Schempp-Hirth&lt;/a&gt;, which is distinctively more blunt (the right picture shows a Discus). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o7drO.jpg&quot; alt=&quot;Alexander Schleicher ASW-20 (left) and Schempp-Hirth Discus T (right)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shorter nose will incur higher induced speeds, but a shorter boundary layer and less wetted surface. Which is better depends on the particular flow situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or take the canopy shape of &lt;a href=&quot;http://en.wikipedia.org/wiki/DG_Flugzeugbau&quot; rel=&quot;noreferrer&quot;&gt;Glaser-Dirks&lt;/a&gt; gliders which stand out with their stretched-out shape which allows even the feet of the pilots to be bathed in sunlight (see picture of a DG-300 below). This is like a brand label.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FHUTd.jpg&quot; alt=&quot;DG-300 over the Alps&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disgruntled Boeing engineers told me once that they spent three months optimizing the tailplane-fuselage intersection of the Boeing 767, only to have their design rejected by upper management because it looked &quot;too much like McDonnell-Douglas&quot;. Yes, the outside shape is important to management to express their brand.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-11T20:58:04.500" LastActivityDate="2015-03-11T20:58:04.500" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13149" PostTypeId="1" AcceptedAnswerId="13155" CreationDate="2015-03-10T08:29:21.753" Score="7" ViewCount="9581" Body="&lt;p&gt;Why are pilots told not to drink alcoholic drinks even after landing, even when their next flight is more than 24 hours later?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this some kind of precautionary rule?&lt;/p&gt;&#xA;" OwnerUserId="7577" LastEditorUserId="15982" LastEditDate="2018-08-30T11:04:06.997" LastActivityDate="2018-08-30T11:04:06.997" Title="Why can't pilots drink alcohol after a flight?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13150" PostTypeId="1" AcceptedAnswerId="13152" CreationDate="2015-03-10T09:16:32.277" Score="16" ViewCount="3950" Body="&lt;p&gt;Following &lt;a href=&quot;https://aviation.stackexchange.com/a/3600/3230&quot;&gt;this answer&lt;/a&gt;. This is actually a set of three different questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How often airlines &quot;wastes&quot; money, by putting long-hauls (widebody aircrafts) on regional or domestic routes?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are there any (economic?) arguments for doing so (except special cases: like no other kind of replacement for broken small plane)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there any example of any regional route, that is served by long-haul on regular basis?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But, I think, that all of them can be answered with one, quite simple answer.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2017-02-12T12:30:24.550" Title="What are the benefits of long-haul airplanes servicing regional routes?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;flight-path&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13151" PostTypeId="1" CreationDate="2015-03-10T11:42:00.923" Score="12" ViewCount="3166" Body="&lt;p&gt;I'm curious as to what it takes to be an Air Traffic Controller. I sat in a preliminary online test after I got accepted in, but it was mindbogglingly difficult. One of the questions I had to do was to add two 8-digit numbers in less then 5 seconds. With such difficult questions in mind, there must be on the job training in addition to class room training as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Q:&lt;/strong&gt; What sort of training is done in becoming an ATC, and what sets the difference between a good ATC and an average ATC?&lt;/p&gt;&#xA;" OwnerUserId="7575" LastEditorUserId="65" LastEditDate="2015-03-10T13:24:26.617" LastActivityDate="2018-07-14T09:35:14.367" Title="What training is required to become an air traffic controller?" Tags="&lt;air-traffic-control&gt;&lt;career&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13152" PostTypeId="2" ParentId="13150" CreationDate="2015-03-10T12:25:11.583" Score="21" Body="&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; You're confusing concepts, planes come in high/low capacity and range, routes come in high/low demand and long/short haul distances. A high capacity long range aircraft can operate very profitably on a short haul, high demand route... a full 747 would actually be more profitable on a 1000km route than a full 737, because although the 747 uses more fuel, it also carries a lot more passengers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You're assuming that putting a big plane on a short route wastes money. Airlines don't work in miles per gallon like you or I do with their car... they work on income/expense. I could fly 747s on 100 mile hops all day, but if they're full of 400+ passengers each paying more than 0.25% of the running costs of that flight, I'll still make money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they &lt;em&gt;could&lt;/em&gt; have used a smaller aircraft, it might waste a&#xA;little money carrying the extra weight, but you seem to be&#xA;over-simplifying things&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing this question is actually more along the lines of &quot;How often do airliners run an aircraft that isn't completely full, and how much of that time could they have actually run a smaller aircraft?&quot; To which the answer is &quot;Usually, and not very often&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The economics are about running the &lt;strong&gt;whole system&lt;/strong&gt; as a profit. If I have enough flights in summer that fill the aircraft, then over 12 months that bigger aircraft (highly profitable all summer, breaking even all winter) may make all money than a smaller aircraft making a small profit all winter, and a small profit all summer, but not being big enough in summer to take the entire potential demand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, though, airlines are in the business of getting the &quot;best fit&quot; for their fleet. They aren't trying to get a plane in every size to have the perfect profit ratio for each flight, they are trying to get a suitable plane on each flight. This involves moving planes around as routes change etc. In an ideal world you'd run each plane exactly full of every passenger who wanted to fly on that route. In reality, we probably want a plane which is just slightly bigger than that, to cope with the small amounts of extra demand&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Again you're seeing &quot;Long haul&quot; and &quot;Short haul&quot; aircraft as different concepts. They aren't. There are only high/low capacity aircraft and high/low capacity routes. Long haul routes tend to have less frequent service with larger, higher capacity aircraft (if you're travelling for 18 hours, you don't need a service with departures every 3 hours). They also tend to involve people travelling from &quot;The UK&quot; to &quot;Australia&quot; for example, so one big plane can cover all of that, and split to smaller aircraft to disperse them&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short haul routes tend to have more regular service and smaller&#xA;demand levels, partially because people are less likely to want to depart at the same time every day, and partially because they can be more fine grained - you can go from an area of one country to an area of another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you seem to miss is that these things are not mutually exclusive... with enough demand, larger aircraft can run short haul routes very profitably. The fact a 747 is &lt;strong&gt;usually&lt;/strong&gt; profitable on long haul flights, and the fact the demand on short haul routes do not &lt;strong&gt;usually&lt;/strong&gt; have enough demand for such a large aircraft, don't mean that one could never be profitable if enough people wanted to fly on it. There are airlines using 777s for example for fairly short haul journeys, very profitably, all over the world.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="7670" LastEditDate="2015-05-23T23:34:56.607" LastActivityDate="2015-05-23T23:34:56.607" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13153" PostTypeId="2" ParentId="13150" CreationDate="2015-03-10T12:26:15.850" Score="5" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747#747SR&quot;&gt;Boeing 747SR&lt;/a&gt; is a short range version of what would normally be considered a long-haul aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To specifically address question 3, it regularly serves the &lt;a href=&quot;http://en.wikipedia.org/wiki/Haneda_Airport&quot;&gt;Tokio International/Haneda (HND)&lt;/a&gt; to &lt;a href=&quot;http://en.wikipedia.org/wiki/Osaka_International_Airport&quot;&gt;Osaka (ITM)&lt;/a&gt; route, which is a flight duration of roughly &lt;a href=&quot;https://www.google.com/maps/dir/Haneda+Airport,+Hanedakuko,+Ota,+Tokyo+144-0041,+Japan/Osaka+International+Airport,+3+Chome-555+Hotarugaike+Nishimachi,+Toyonaka,+Osaka+Prefecture+560-0036,+Japan/@35.1354251,135.2483118,7z/data=!4m14!4m13!1m5!1m1!1s0x6018640ba43192e3:0xd32c3a9d146f8df!2m2!1d139.779839!2d35.549393!1m5!1m1!1s0x6000f06df58777b9:0x7411a874d9df4cd!2m2!1d135.43809!2d34.78958!5i2&quot;&gt;1:05&lt;/a&gt;. &lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot;&gt;JAL 123&lt;/a&gt; is a well known accident on that route.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-03-10T12:26:15.850" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13154" PostTypeId="1" AcceptedAnswerId="13158" CreationDate="2015-03-10T12:47:51.610" Score="18" ViewCount="19449" Body="&lt;p&gt;In most commercial flights where headphones are provided for inflight entertainment they have two pins, unlike single pin connections which we use on the ground (e.g. for mobile phones).&#xA;Is there a particular reason why it is done that way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason could be that people can steal a single pin headphone. But still it is not compelling enough reason.&lt;/p&gt;&#xA;" OwnerUserId="7065" LastEditorUserId="62" LastEditDate="2015-03-10T13:11:15.577" LastActivityDate="2015-03-11T16:34:25.943" Title="Why do entertainment system headphones on aircraft have two pins?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13155" PostTypeId="2" ParentId="13149" CreationDate="2015-03-10T13:02:01.107" Score="23" Body="&lt;p&gt;Commercial pilots (in the United States) are usually not allowed to drink while on duty regardless of their flight status because, among other things, it would be frightening to any prospective passengers who might see them drinking. For example, &lt;strong&gt;American Airlines&lt;/strong&gt; strictly forbids consuming alcohol or any intoxicant publicly while in uniform. Here is the exact text of their company policy:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Rule 25&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Unauthorized possession or using any intoxicants on Company premises&#xA;  at any time, or drinking intoxicants in public while wearing a uniform&#xA;  with Company emblem or insignia is prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that this does not disallow drinking as long as it is (1) not on company premises, and (2) is in private. Obviously, if the person is a US crewmember then they must adhere to FAA rules in addition to company rules (see &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/28757d8ae4d7d671862571960066be86!OpenDocument&quot;&gt;FAR Section 91.17&lt;/a&gt; for details on those rules).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-27T15:36:26.380" LastActivityDate="2015-03-27T15:36:26.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13157" PostTypeId="2" ParentId="11536" CreationDate="2015-03-10T13:09:51.380" Score="1" Body="&lt;p&gt;As a CFI, whether I was giving instruction to a student pilot or in a jet, I would always give the same briefing concerning who would be in what role during an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The briefing would discuss numerous scenarios, but specifically address who will be the PF given their experience, recency, and time in type. This would always change from pilot to pilot and may change as the student gained time and experience. It's always a good idea to have a plan of action discussed well ahead of any departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example is the &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow&quot;&gt;Miracle on the Hudson&lt;/a&gt;: Jeff Skilling was the PF and Sully was the PM when they departed. It was briefed that in the event of an emergency, Sully would handle the radios and fly the aircraft while Jeff would ran the emergency checklist, so as soon as they loss thrust Jeff transferred controls over to Sully and we all saw what happens when preparation and luck come together at a point in time.&lt;/p&gt;&#xA;" OwnerUserId="7188" LastEditorUserId="1467" LastEditDate="2015-03-10T17:04:08.330" LastActivityDate="2015-03-10T17:04:08.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13158" PostTypeId="2" ParentId="13154" CreationDate="2015-03-10T13:21:58.980" Score="15" Body="&lt;p&gt;The three main reasons are:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Prevent theft of headphones due to incompatibility with home systems&lt;/li&gt;&#xA;&lt;li&gt;Redundancy, if one connector breaks, the other will still provide audio&lt;/li&gt;&#xA;&lt;li&gt;Before the 3.5mm jack was used, a pneumatic system was in use, which required two connectors.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This question has been asked on different websites already, but here is a detailed explanation that sums it up nicely:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;There are a couple main reasons:&lt;/p&gt;&#xA;&lt;p&gt;First, the airlines were trying to prevent theft of headphones. The two-pronged plugs have been around on airplanes since way before the airlines started charging for headsets. Back then, headphones were not usually easily carried around as the portable earbud style had not become popular yet. By using a two-pronged setup that is not used in most other audio systems, the motivation for passengers to steal the headsets went down immensely.&lt;/p&gt;&#xA;&lt;p&gt;The second reason is redundancy. When a standard stereo headphone jack with three internal connections (right, left, and ground) breaks, you will often lose audio in both the left and right channels. However, with the two-pronged design, if one of the jacks breaks then there will still be audio going through the other channel. While this is annoying for the user, it is an easy way for the airline to defer maintenance on that individual seat's audio system until both the left and right channel are non-functional.&lt;/p&gt;&#xA;&lt;p&gt;The two-prong design is a relic of the past, before headphones were bundled with so many of the mobile devices we now buy. Planes with updated inflight entertainment (IFE) systems usually have the standard stereo jack as most passengers prefer using their own headsets now. Slowly these old connectors will be completely phased out.&lt;/p&gt;&#xA;&lt;p&gt;Another less obvious (and probably less likely, but interesting nonetheless) reason, though, is based on airline complacency. Airlines, especially US based airlines, are notoriously slow in changing their tactics. Back before the 3.5mm jack became the standard for headphone audio connections for IFEs, airplanes used a pneumatic headphone design. These headphones were similar to stethoscopes where hollow tubes would be plugged into the armrest which had actual soundwaves coming out (instead of analog electrical signals). These systems were much more reliable than the standard electrical system and the headsets themselves were very cheap to replace. Since the pneumatic system required two separate plugs for the left and right channel (since you cannot mix physical sound waves into a single hole), all armrests were designed with two holes for audio. Airlines were likely so used to having two jacks for audio that they continued with the same design when they switched to electrical audio signals.&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.quora.com/Why-do-airplanes-use-two-pronged-headphones&quot; rel=&quot;noreferrer&quot;&gt;www.quora.com&lt;/a&gt; - Author: Raj Misra)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-11T16:34:25.943" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="13160" PostTypeId="2" ParentId="8101" CreationDate="2015-03-10T13:25:29.657" Score="0" Body="&lt;p&gt;I think the appropriate term would simply be &quot;crew&quot;. Since you may or may not have known who was the Pilot Flying (PF) on that good or terrible landing you can just say good job crew!&lt;/p&gt;&#xA;" OwnerUserId="7188" LastEditorUserId="65" LastEditDate="2015-03-10T13:53:00.717" LastActivityDate="2015-03-10T13:53:00.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13161" PostTypeId="2" ParentId="12048" CreationDate="2015-03-10T13:34:14.227" Score="1" Body="&lt;p&gt;The proper response to losing the engine would be to follow the emergency procedures checklist. In that you will find it says to deploy the ballistic parachute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While a better option, the ballistic parachute has its own drawbacks. I recall when getting checked out in a Cirrus years ago by an approved training provider that I was told the impact with chute deployed can be up to 8 G's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I would say not 100% survivable. Actually I know of a Cirrus that went down near Sanford Florida a few years back that deployed the chute and the occupants died.&lt;/p&gt;&#xA;" OwnerUserId="7188" LastEditorUserId="3201" LastEditDate="2015-03-10T18:45:46.763" LastActivityDate="2015-03-10T18:45:46.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13162" PostTypeId="2" ParentId="13151" CreationDate="2015-03-10T13:46:24.993" Score="2" Body="&lt;p&gt;I dont know about paper and classroom training but they do train in the tower at KPNE where I fly. I know this because they sometimes tell you if they are training a new guy. This happened to me just the other night. I was flying in the pattern with my instructor (practicing night landings) and we were the only people around that evening. The tower told us they had a trainee in and we were good practice for them (they even asked us to stay out longer). They had him take us through both left and right traffic patterns and do a few leg extensions and what not. Nothing to out of the norm. I think one other plane came in while we were in the pattern but nothing that he could not handle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is that they start people at smaller towered airports, if you become senior enough/good enough to move to a bigger one you step up like in any other job. I would think they don't train guys at major airports but I cant state that as an actual fact.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-10T13:46:24.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13163" PostTypeId="1" CreationDate="2015-03-10T13:58:04.707" Score="0" ViewCount="3730" Body="&lt;p&gt;I noticed sometimes aircraft taxi with the logo light illuminating their tail, while others have it off. So is turning on the tail light at the discretion of the pilot?&lt;/p&gt;&#xA;" OwnerUserId="7586" LastEditorUserId="1696" LastEditDate="2015-03-10T14:17:10.807" LastActivityDate="2015-03-10T14:22:24.013" Title="When is the logo light on the tail turned on?" Tags="&lt;aircraft-systems&gt;&lt;ground-operations&gt;&lt;taxiing&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-03-10T14:53:01.653" ContentLicense="CC BY-SA 3.0" />
  <row Id="13164" PostTypeId="2" ParentId="13163" CreationDate="2015-03-10T14:17:15.650" Score="0" Body="&lt;p&gt;There can be several lights on the empennage (tail section) of an airplane. There are two as shown here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UuKn5.jpg&quot; alt=&quot;Lights&quot;&gt;&lt;br&gt;&#xA;&lt;sub&gt;&lt;a href=&quot;http://learntofly.ca/aircraft-navigation-lights/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The red light is called aircraft beacon. The white light is called strobe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When to turn them on is &lt;a href=&quot;http://en.wikipedia.org/wiki/Navigation_light#Aviation_navigation_lights&quot; rel=&quot;nofollow noreferrer&quot;&gt;explained here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All aircraft built after 11 March 1996 must have an anti-collision&#xA;  light system (strobe lights or rotating beacon) turned on for all&#xA;  flight activities in poor visibility. The anti-collision system is&#xA;  recommended in good visibility, where only strobes and beacon are&#xA;  required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another one is logo light:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TltHM.jpg&quot; alt=&quot;Logo Light&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This light illuminates the livery design on the vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more details, please see this question:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/64/65&quot;&gt;When to use Beacon, Anti Collision, Strobe, Logo and Navigation lights?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-03-10T14:22:24.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13165" PostTypeId="1" AcceptedAnswerId="13167" CreationDate="2015-03-10T15:21:07.037" Score="15" ViewCount="3911" Body="&lt;p&gt;I saw this image of a Cessna 172's tail posted on another question and it made me wonder why the beacon light is basically a cylinder, and not a more aerodynamic, teardrop shape?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xxAAJ.jpg&quot; width=&quot;500&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://learntofly.ca/aircraft-navigation-lights/&quot; rel=&quot;noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="6979" LastEditDate="2015-03-10T23:06:23.377" LastActivityDate="2015-03-10T23:06:23.377" Title="Why are aircraft external lights round, not tear-drop shaped?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;visibility&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13166" PostTypeId="2" ParentId="13165" CreationDate="2015-03-10T16:23:28.290" Score="14" Body="&lt;p&gt;Your assumption that all are round is faulty, plenty are teardrop shaped. &lt;img src=&quot;https://i.stack.imgur.com/PY1WI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll see round ones on many slower aircraft where streamlining isn't as big an issue, however on faster aircraft they are almost always aerodynamic. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-03-10T16:23:28.290" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13167" PostTypeId="2" ParentId="13165" CreationDate="2015-03-10T17:15:17.703" Score="18" Body="&lt;p&gt;That beacon lens (and most of the strobe lenses shaped like it) are actually &lt;a href=&quot;http://en.wikipedia.org/wiki/Fresnel_lens&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fresnel lenses&lt;/a&gt;.&lt;br&gt;&#xA;They are optically designed to produce a specific plane &amp;amp; intensity of coverage, and tinted for a specific color. (The color, intensity, and plane are &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/54887454079d27d786256dc60069639f/$FILE/C96a.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;specified in the FARs &amp;amp; applicable Technical Standard Orders&lt;/a&gt; if you want to go hunt down the requirements.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lens optics are easier to see on the split (Red/White) lenses:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/aBNbR.jpg&quot; alt=&quot;Whelen Red/White strobe lens&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Fresnel lens is not the only way to meet these requirements, &lt;a href=&quot;https://i.stack.imgur.com/UJg73.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;some anti-collision lights do it by sheer intensity&lt;/a&gt; (while retaining the &quot;jar&quot; shape, mainly for installation compatibility), and as &lt;a href=&quot;https://aviation.stackexchange.com/a/13166&quot;&gt;GdD pointed out there are more aerodynamic options available&lt;/a&gt;. The Fresnel lens method is usually adequate for smaller/slower aircraft however, and the drag penalty at relatively low speeds isn't significant enough for designers to worry about.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-10T20:07:11.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13168" PostTypeId="2" ParentId="13151" CreationDate="2015-03-10T17:37:30.747" Score="7" Body="&lt;p&gt;The test you took was probably the &lt;a href=&quot;http://www.stuckmic.com/air-traffic-standardized-aptitude-test-at-sat.html&quot;&gt;AT-SAT (Air Traffic Standardized Aptitude Test)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on those results (and assuming you didn't completely blow it) you'll be sorted and assigned to a class at the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/arc/programs/academy/tech_training/ama500.cfm&quot;&gt;FAA Academy&lt;/a&gt; for classroom and &lt;a href=&quot;https://www.youtube.com/watch?v=ksBNEZVqdxg&quot;&gt;simulator&lt;/a&gt; training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you're proficient in the simulator and have completed the required classroom instruction you'll be assigned to a facility for training as a &quot;developmental controller&quot;. You will shadow a fully certified controller, and eventually work live traffic under their supervision while learning local procedures and how the airspace system works in the real world (as opposed to the simulators you trained in).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually you will have completed the local training required and demonstrated your ability to work traffic to your supervisor, and you will be &lt;a href=&quot;http://avstop.com/careers/controltower.html&quot;&gt;certified as a &quot;full performance level&quot; controller&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for what it takes to be a good controller, the standard answer is &quot;If you would make a good waiter (or waitress) you will probably be a good controller.&quot;&lt;br&gt;&#xA;The ability to see and anticipate a situation developing and take appropriate actions is probably the most vital skill (for wait staff it's making sure everyone's glass is full, for controllers it's making sure traffic is sequenced in a way that keeps things moving along in a safe, orderly, and efficient manner).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that it's hard to really say what makes a &quot;good&quot; controller, because everyone is looking for something different. (A &quot;good&quot; controller for a pilot gives them the clearances they want, when they want them. A &quot;good&quot; controller for the system occasionally gives a pilot a less-than-optimal routing or a delay vector in order to keep some other part of the system with more traffic volume moving smoothly.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-10T17:37:30.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13169" PostTypeId="1" AcceptedAnswerId="13170" CreationDate="2015-03-10T19:47:13.463" Score="7" ViewCount="1830" Body="&lt;p&gt;In &lt;a href=&quot;http://youtu.be/ztqZvTfAMLI?t=4m23s&quot; rel=&quot;noreferrer&quot;&gt;this video (marker 4:23)&lt;/a&gt;, what button is the pilot thumbing on the yoke?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="65" LastEditDate="2015-03-10T20:13:06.310" LastActivityDate="2015-04-08T16:05:25.107" Title="What button is this pilot pressing with his thumb?" Tags="&lt;flight-controls&gt;&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13170" PostTypeId="2" ParentId="13169" CreationDate="2015-03-10T19:52:00.457" Score="10" Body="&lt;p&gt;It's the elevator trim control to relieve control forces in pitch.  It does this by changing the neutral position of the elevators so that the pilot flying does not need to maintain a constant pressure on the yoke to maintain pitch.  On the 747 family, this is achieved by moving the stabiliser.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although &lt;a href=&quot;http://www.cockpitbuilders.com/community/index.php?action=dlattach;topic=633.0;attach=525;image&quot; rel=&quot;nofollow noreferrer&quot;&gt;this image&lt;/a&gt; shows a home cockpit yoke, the representation of the controls is accurate:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bwy7a.jpg&quot; alt=&quot;747 yoke trim switches&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-03-11T19:28:35.243" LastActivityDate="2015-03-11T19:28:35.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13171" PostTypeId="2" ParentId="13132" CreationDate="2015-03-10T20:26:33.107" Score="2" Body="&lt;p&gt;I am going to answer this in another way.&lt;br&gt;&#xA;Generally this is by design. The wheels are not the real issue, the angle of attack is.&#xA;When most aircraft land, they are &quot;flaring&quot; or pointing the leading edge of the wings as high as possible without getting into stall territory.  This is especially true for hang gliders and parachute canopies, even though neither of these have wheels.&#xA;It is called flaring as this is what it is called when birds land. (Ducks, Pelicans etc.)&#xA;In this aspect, a nose wheel is going to be higher, and hence touch down last.&#xA;Even a tail dragger is looking at this until the last moment. It's really a powered glide.&#xA;A pilot will avoid a stall, look for &quot;ground effect&quot;, and be mindful of recovery options.&#xA;The design of the landing gear reflects this strategy, if a commercial ariliner touched town nose first (levelish) it would be travelling faster and experience more of a shock, the gear would need to be much heavier. This type of pancake landing does not usually end well. &lt;/p&gt;&#xA;" OwnerUserId="7597" LastActivityDate="2015-03-10T20:26:33.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13172" PostTypeId="2" ParentId="13151" CreationDate="2015-03-10T20:27:29.250" Score="10" Body="&lt;p&gt;Training for US path is(I'll take this information, post hiring, since they keep changing how they hire, and assign facilities, also length of times are approximate and might vary):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA Academy(Oklahoma City, OK):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;~6 week AT Basics Course(If you went to a CTI(College Training Initiative) school, this course is skipped)&lt;/li&gt;&#xA;&lt;li&gt;Then if you're split depending on which area you're going to, Enroute, Tower, or TRACON.&lt;/li&gt;&#xA;&lt;li&gt;Tower course is ~8 weeks,  TRACON course is 1 month (or 2 if you're going to a bigger facility and they put you in a supplemental course), and Enroute, I'm not positive is around 10 weeks or so.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Then you move to your facility. At your facility, your first days you'll spend learning various materials, and then be given classroom training, including Computer based instruction, an actual instructor time(if the facility is large enough), and also lots of study time to memorize all the maps, and various items you will be tested on. Then, if your facility has the ability, you'll do some simulator problems. Note: you might only get the classroom and simulator for only a subset of positions at the facility, depending on how they break up the training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then after all that, you head out to the operation, and will usually start training on some subset of positions that are at the facility. You'll receive training on each position, until you've demonstrated that you're competent to work it on your own. Once/if you get to that point, you're given a certification check by your supervisor, and if you pass you're certified to work that position. And you repeat that process for each position, and possibly having to return to classrooms/simulators for any additional positions, and repeating the process again. Once you've finished all the positions you need you're a fully certified controller at that facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each time you move to a new facility, you will have to repeat the classroom and simulator, and on the job training at the positions at that new facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's far more detail and nuance than I can easily explain here, but this is a general overview of the process.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="2785" LastEditDate="2015-03-12T00:25:05.530" LastActivityDate="2015-03-12T00:25:05.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13173" PostTypeId="2" ParentId="13165" CreationDate="2015-03-10T22:08:21.220" Score="9" Body="&lt;p&gt;Taking a look to the photograph you are showing not only the lights are not very aerodynamic, you can see as well that the fairing on the tail could have a softer transition, the rivets used are not the ones used in commercial het airplanes and transition between plates is also not smooth. You can see that the aerodynamics is open to improvements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is overall airplane optimization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cessna 172 is an small airplane of 3 passenguers and one pilot. Customers of this airplane will be mainly of 2 kinds:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Small airlines making short flights between 2 places very close.&lt;/li&gt;&#xA;&lt;li&gt;Private use.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Notice that although the airplane has an autonomy of 1200km, usually is not able to compete in routes of that distance as airplanes like A320 will be able to offer a cheaper ticket. Is a typical airplane for travels between islands with low traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that context...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For the airline, as there will no be a big traffic, the main cost will be amortization of the airplane, also trips between 2 points will be usually very short, so the most part of the use of the airplane will be in ground taxing the airport.&lt;/li&gt;&#xA;&lt;li&gt;For the private use, it will be an airplane not used regularly and the flying time, in the life of the airplane, will be really limited.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the overall context of the lifetime of the airplane the fuel consumption (driven by the aerodynamic drag) will be smaller than the effect of the amortization of the airplane (capital costs) and maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order ot reduce aerodynamic drag and fuel comsuption in general (weight reduction), that will imply extra costs on each manufactured airplane:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Add-hoc design of components not using standards.&lt;/li&gt;&#xA;&lt;li&gt;Higher quality standards and control.&lt;/li&gt;&#xA;&lt;li&gt;Higher costs of development (NRC).&lt;/li&gt;&#xA;&lt;li&gt;High costs materials.&lt;/li&gt;&#xA;&lt;li&gt;More costly manufacturing shapes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Basically the manufacturer (Cessna) needs to make a decision between:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Making a relatively cheaper airplane with higher fuel consumption.&lt;/li&gt;&#xA;&lt;li&gt;Making a costly airplane efficient in fuel consumption&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In that trade-off, for this specific model and my understanding of the customer objective, is more attractive to create a cheaper airplane.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-03-10T22:08:21.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13174" PostTypeId="1" AcceptedAnswerId="13176" CreationDate="2015-03-10T23:23:17.180" Score="12" ViewCount="1356" Body="&lt;p&gt;I seemingly can't find an answer to this quite obvious question: &#xA;What's the preferred approach procedure for a passenger jet at a modern airport fully equipped for precision ILS (both aircraft and airport): ILS or visual approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's ILS, what would cause a visual approach to be flown (except for the ILS not working of course)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's visual, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a. why? (ILS seems more secure from my naive standpoint) &lt;/li&gt;&#xA;&lt;li&gt;b. what would be the cause to do ILS instead? Bad weather / sight for instance?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is the decision made only by the tower or does the captain of the aircraft have any saying in it? &lt;/p&gt;&#xA;" OwnerUserId="7598" LastActivityDate="2016-01-10T08:01:23.393" Title="What's the preferred approach for a passenger jet?" Tags="&lt;approach&gt;&lt;visual-approaches&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13175" PostTypeId="2" ParentId="8633" CreationDate="2015-03-10T23:30:55.397" Score="10" Body="&lt;p&gt;You can't land just any plane on an aircraft carrier, it has to have tail hooks and the pilot needs special training. The Aussie F/A-18s are not equipped to land on aircraft carriers. So they have to do short 'hops' or in flight re-fuel.&lt;/p&gt;&#xA;" OwnerUserId="7599" LastEditorUserId="774" LastEditDate="2015-03-11T02:09:46.817" LastActivityDate="2015-03-11T02:09:46.817" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13176" PostTypeId="2" ParentId="13174" CreationDate="2015-03-10T23:56:14.480" Score="14" Body="&lt;p&gt;I'll give the answer from an ATC perspective. A visual approach is the most preferred approach, since we can get aircraft to follow each other, and don't have to worry as greatly about aircraft getting too close. The rules say we can compress under certain conditions to 2.5 miles on ILS or radar separation approaches, but timing wise, for the runway to be clear, you can often need less separation between aircraft to maximize its usage. With the visual approach, you're vectoring to keep aircraft closer so they can see each other and follow in closely to each other to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most ATC facilities, the Tower decides what runway to use, and the approach control calls the type of approach generally on offer(this can vary depending on facilities and how they agree to run things). A pilot can always request a different approach... they might be delayed, sometimes significantly if they insist on something way out of the loop.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-03-10T23:56:14.480" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13177" PostTypeId="2" ParentId="13149" CreationDate="2015-03-11T01:51:56.523" Score="13" Body="&lt;p&gt;Pilots absolutely can drink after a flight once off duty, just not in uniform.  Every company I'm aware of prohibits alcohol consumption in uniform while in view of the public.  This prohibition is about maintaining an image and to not associate drunk pilots with the airline.  The regulations have no verbiage about uniforms but stipulate no one on-duty may consume alcohol.&lt;/p&gt;&#xA;&lt;p&gt;The rules for air carrier pilots is laid out in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A3.0.1.1.6#se14.3.120_137&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 120.37&lt;/a&gt; (excerpt):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(b) Alcohol concentration. No covered employee shall report for duty or remain on duty requiring the performance of safety-sensitive functions while having an alcohol concentration of 0.04 or greater. No certificate holder having actual knowledge that an employee has an alcohol concentration of 0.04 or greater shall permit the employee to perform or continue to perform safety-sensitive functions.&lt;/p&gt;&#xA;&lt;p&gt;(c) On-duty use. No covered employee shall use alcohol while performing safety-sensitive functions. No certificate holder having actual knowledge that a covered employee is using alcohol while performing safety-sensitive functions shall permit the employee to perform or continue to perform safety-sensitive functions.&lt;/p&gt;&#xA;&lt;p&gt;(d) Pre-duty use. (1) No covered employee shall perform flight crewmember or flight attendant duties within 8 hours after using alcohol. No certificate holder having actual knowledge that such an employee has used alcohol within 8 hours shall permit the employee to perform or continue to perform the specified duties.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The rule here is 8 hours &amp;quot;bottle to throttle&amp;quot; and at the end of those 8 hours for BAC must be less than 0.04.&lt;/p&gt;&#xA;&lt;p&gt;14 CFR part 121 Appendix J further stipulates that pilots may not perform &amp;quot;safety sensitive&amp;quot; functions until BAC is below 0.02.  Additionally, many company operating manuals (FAA approved) require 12 hours between alcohol consumption and the beginning of a duty period.&lt;/p&gt;&#xA;&lt;p&gt;For most pilots, the rule is 12 hours &amp;quot;bottle to throttle&amp;quot; and BAC &amp;lt; 0.02.  This means a pilot, once off-duty and out of uniform, can enjoy a drink as long as the overnight is longer than 12 hours.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-11T02:01:47.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13178" PostTypeId="1" CreationDate="2015-03-11T03:07:03.697" Score="1" ViewCount="589" Body="&lt;p&gt;I am researching how much force is needed to divert the thrust of a Boeing 787 on its service ceiling of 13,100 meters and at a cruising speed of 913 km/h (data found on &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I would like to fit a diverter to it, what is the diameter of the nozzle of &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot; rel=&quot;nofollow&quot;&gt;Trent 1000 engine&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="7600" LastEditorUserId="65" LastEditDate="2015-03-11T13:47:44.810" LastActivityDate="2015-03-11T14:10:14.300" Title="What is the diameter of the nozzle of Trent 1000?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13180" PostTypeId="2" ParentId="13116" CreationDate="2015-03-11T06:32:17.500" Score="4" Body="&lt;p&gt;I suspect the rules and motivations will vary from country to country. Starting with the rules, for example, &lt;a href=&quot;http://www.comlaw.gov.au/Details/F2009C01019&quot; rel=&quot;nofollow&quot;&gt;ANR 25&lt;/a&gt; (1) specifies that:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; A person shall not smoke anywhere in a prescribed aircraft.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;While ANR 25 (6) specifies that:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;prescribed aircraft means an aircraft that:&#xA;  (a) is a regular public transport aircraft, or an open‑use charter aircraft; and&#xA;  (b) is engaged in:&#xA;    (i) the carriage of passengers between airports in Australian territory; or&#xA;    (ii) Australian international carriage (except the carriage of freight only)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;That effectively criminalises smoking on scheduled domestic and international flights as well as charter flights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, &lt;a href=&quot;http://www5.austlii.edu.au/au/legis/cth/consol_reg/car1988263/s255.html&quot; rel=&quot;nofollow&quot;&gt;CAR 255&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; (1) Subject to subregulation (1A), a person must not smoke:&#xA;   (a) in a part of an aircraft in which a notice is permanently displayed indicating that smoking is prohibited at all times or without specifying a period during which smoking is prohibited;&#xA;   (b) anywhere in an aircraft during take-off, landing or refuelling or during a period:&#xA;     (i) in which a notice is temporarily displayed indicating that smoking is prohibited; or&#xA;     (ii) which is specified in a permanently displayed notice as a period during which smoking is prohibited;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Which effectively criminalises smoking on any aircraft where any kind of no smoking sign has been placed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons stated for the smoking ban vary (and are not usually stated in the laws or regulations themselves), but generally include (1) &lt;a href=&quot;http://www.tobaccoinaustralia.org.au/fandi/fandi/c06s12.htm&quot; rel=&quot;nofollow&quot;&gt;safety of air crew and passengers&lt;/a&gt;, (2) &lt;a href=&quot;http://www.theaustralian.com.au/in-depth/cabinet-papers/australia-first-to-ban-smoking-on-all-domestic-flights/story-fnkuhyre-1226793080767&quot; rel=&quot;nofollow&quot;&gt;cost savings for airlines&lt;/a&gt; and (3) &lt;a href=&quot;http://www.theaustralian.com.au/in-depth/cabinet-papers/australia-first-to-ban-smoking-on-all-domestic-flights/story-fnkuhyre-1226793080767&quot; rel=&quot;nofollow&quot;&gt;eliminating conflict between smoking and non-smoking passengers&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-03-11T06:32:17.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13181" PostTypeId="2" ParentId="8022" CreationDate="2015-03-11T08:12:21.043" Score="8" Body="&lt;p&gt;It's assumed that deep stall mainly affects T tails, but high angles of attack may lead to a more conventional low tail design having the tail stalled.  If you look for the accident investigation &lt;a href=&quot;https://www.youtube.com/watch?v=n-hbWO0gL6g&quot;&gt;animation of AF447 (youtube)&lt;/a&gt;, you will see that there was a lot of ineffective stick movement.  Finally, when the stick went forward, the nose lowered to about 10 degrees down, but the flight path angle was close to -45 degrees, so the angle of attack was roughly 35 degrees.  Both surfaces were deeply stalled and this manoeuvre was survivable with conventional stall recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are recovery techniques which may work.  I used to air test a large T tail design and the briefed manoeuvre was to roll to induce side-slip which would reduce the angle of attack.  On a T tail design, this would mainly be accomplished by rudder.  But a low tail design may have the rudder blanked by the tail at these angles of attack.  The only way to induce roll from yaw in this case would be the use of asymmetric thrust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AF447 pilots were not equipped with this knowledge which may have saved the aircraft.  I have asked my colleagues their opinion and I get the impression there is not much appreciation of this situation.  With the recent Air Asia accident investigation follow a similar approach to the events leading to the loss of AF447, perhaps now is the time.&lt;/p&gt;&#xA;" OwnerUserId="7604" LastEditorUserId="19" LastEditDate="2015-03-11T10:09:31.390" LastActivityDate="2015-03-11T10:09:31.390" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13182" PostTypeId="2" ParentId="1507" CreationDate="2015-03-11T08:41:29.690" Score="8" Body="&lt;p&gt;The Swiss Air Force flew &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Hunter&quot;&gt;Hawker Hunter&lt;/a&gt;s for three decades. Soon the pilots noticed that spin characteristics differed between individual aircraft. One would only spin in one direction, one would not get into a spin at all, and another would spin well left and right. The British never bothered to look deeper into this, but to the Swiss this was unacceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally they found out that manufacturing tolerances made the nose gear doors close differently. On some aircraft, the left door would stick out a little more, on some it was the right door. Also the gap size was not identical between aircraft, and that determined the spin characteristics. Of course, soon all Swiss Hunters would spin identically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also remember that one Luftwaffe pilot told me that they would test fly their new &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Ju_88&quot;&gt;Junkers 88&lt;/a&gt;s upon receiving them from the factory and found speed differences of maybe 20 km/h between individual aircraft from the same production batch. Then they proceeded to polish the normally matte paint of the fastest ones to have a super-fast plane for special missions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Manufacturing tolerances might be small, but in some cases they can add up to produce noticeably different outcomes. Computerized and automated processes have drastically reduced those differences lately, however.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-03-11T08:41:29.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13184" PostTypeId="1" AcceptedAnswerId="13198" CreationDate="2015-03-11T12:02:52.647" Score="18" ViewCount="9326" Body="&lt;p&gt;While going through an article on AFO, I came across this little piece of info:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MuIas.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So, does it have retractable steps on all its exit doors? How does it manage doors like these?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/B7wSp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="790" LastEditDate="2015-03-12T13:38:16.740" LastActivityDate="2017-03-06T18:06:30.977" Title="Does Air Force One (VC-25) have retractable staircases on all its exit doors?" Tags="&lt;aircraft-design&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13185" PostTypeId="2" ParentId="13184" CreationDate="2015-03-11T12:09:33.840" Score="16" Body="&lt;p&gt;It doesn't have retractable stairs on every door; the second picture shows mobile stairs to the upper exit (you can see the driver's cabin behind the crowd).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If mobile stairs aren't available the president will descend to the lower level and use the built in stairs at the lower exit as shown in the first picture. If they are available (and deemed to be safe by the bodyguards) they will be used.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="97" LastEditDate="2015-03-11T20:21:05.180" LastActivityDate="2015-03-11T20:21:05.180" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13187" PostTypeId="2" ParentId="13178" CreationDate="2015-03-11T14:10:14.300" Score="2" Body="&lt;p&gt;It is mentioned here that the fan diameter is about 111-112 inches. So the nozzle must be smaller than that as the engine assembly narrows at its rear end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/2012_consortium/media/Boeing_CLEEN_Projects_Briefing.pdf&quot; rel=&quot;nofollow&quot;&gt;PDF (p.5)&lt;/a&gt; shows a diagram of the exhaust nozzle of RR Trent 1000 measuring the diameter as &lt;strong&gt;63&lt;/strong&gt; inches. This is the only reference I could find.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-11T14:10:14.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13188" PostTypeId="2" ParentId="1614" CreationDate="2015-03-11T15:20:24.700" Score="1" Body="&lt;p&gt;You can check it out &lt;a href=&quot;http://www.ijirset.com/upload/may/57_2D%20ANALYSIS.pdf&quot; rel=&quot;nofollow&quot;&gt;here (PDF)&lt;/a&gt;. Good luck.&lt;/p&gt;&#xA;" OwnerUserId="7608" LastEditorUserId="65" LastEditDate="2015-03-11T15:38:22.080" LastActivityDate="2015-03-11T15:38:22.080" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13189" PostTypeId="1" AcceptedAnswerId="13190" CreationDate="2015-03-11T19:59:09.860" Score="21" ViewCount="3115" Body="&lt;p&gt;On &lt;em&gt;almost&lt;/em&gt; all airliners I have seen, the doors are painted inside a rectangle which appear to reflect more light. This is the case whether in the aircraft has its manufacturer's paint or an airline's custom livery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason behind this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;It can be seen in these pictures.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OICEY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OICEY.jpg&quot; alt=&quot;Airbus 380&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;&lt;em&gt;&lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/8/82/Airbus_A380_blue_sky.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zkLJE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zkLJE.jpg&quot; alt=&quot;Boeing 787&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;&lt;em&gt;&lt;a href=&quot;http://www.3dincites.com/wp-content/uploads/boeing-787.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="5517" LastEditDate="2015-03-12T17:26:37.357" LastActivityDate="2015-03-12T17:26:37.357" Title="Why are cabin doors outlined with a different color than the fuselage?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-maintenance&gt;&lt;fuselage&gt;&lt;livery&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13190" PostTypeId="2" ParentId="13189" CreationDate="2015-03-11T19:59:09.860" Score="27" Body="&lt;p&gt;The doors are painted like this because it is a federal law that all cabin doors on commercial airplanes should be outlined in a color which contrasts with the fuselage color. It is done so that in case of an emergency on ground, rescue crew can find the doors easily and open them quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It happened in past years that passengers survived some crash landings (especially at night) but perished because the rescue crews could not locate the cabin doors in time to rescue them from the burning airplane. The contrasting outlines of the doors allow them to find the doors instantly.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here is the actual text of this federal regulation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.811&quot;&gt;14 CFR 25.811 (f) Emergency exit marking&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;(f)&lt;/strong&gt; Each emergency exit that is required to be openable from the&#xA;  outside, and its means of opening, must be marked on the outside of&#xA;  the airplane. In addition, the following apply:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The outside marking for each passenger emergency exit in the side&#xA;  of the fuselage must include a 2-inch colored band outlining the exit.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Each outside marking including the band, must have color contrast&#xA;  to be readily distinguishable from the surrounding fuselage surface.&#xA;  The contrast must be such that if the reflectance of the darker color&#xA;  is 15 percent or less, the reflectance of the lighter color must be at&#xA;  least 45 percent. “Reflectance” is the ratio of the luminous flux&#xA;  reflected by a body to the luminous flux it receives. When the&#xA;  reflectance of the darker color is greater than 15 percent, at least a&#xA;  30-percent difference between its reflectance and the reflectance of&#xA;  the lighter color must be provided.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) In the case of exits other than those in the side of the&#xA;  fuselage, such as ventral or tailcone exits, the external means of&#xA;  opening, including instructions if applicable, must be conspicuously&#xA;  marked in red, or bright chrome yellow if the background color is such&#xA;  that red is inconspicuous. When the opening means is located on only&#xA;  one side of the fuselage, a conspicuous marking to that effect must be&#xA;  provided on the other side.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-03-12T13:26:08.850" LastActivityDate="2015-03-12T13:26:08.850" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13191" PostTypeId="2" ParentId="11393" CreationDate="2015-03-11T20:31:15.350" Score="10" Body="&lt;p&gt;Jon Story's answer is correct, but I will add that the cabin displays often have incorrect information on them. I have seen wrong times, wrong locations, impossible flight paths, impossible air speeds, etc. The mere fact they call it an &quot;entertainment system&quot; tells you something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect the altitude may be coming from a cheap, dedicated GPS unit. A lot of GPSs have inaccurate altitudes. Some have a &quot;barometric&quot; sensor-derived altitude which is often wildly incorrect.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-11T20:31:15.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13192" PostTypeId="1" CreationDate="2015-03-11T21:14:27.837" Score="8" ViewCount="551" Body="&lt;p&gt;During a race do the pilots adjust their throttle settings to control speed, or do they leave the throttle wide open the entire time?&lt;/p&gt;&#xA;" OwnerUserId="7613" LastEditorUserId="62" LastEditDate="2015-03-11T21:31:01.620" LastActivityDate="2015-03-18T07:51:51.247" Title="Do pilots adjust the throttle setting during a Red Bull air race?" Tags="&lt;flight-controls&gt;&lt;air-race&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13193" PostTypeId="2" ParentId="1614" CreationDate="2015-03-11T21:27:50.787" Score="1" Body="&lt;p&gt;This is not easy. The quickest way is to google for pictures of compressor flow CFD results, like the one below. The full resolution picture can be found &lt;a href=&quot;http://pantar.cerfacs.fr/images/cerfacs_cfd/gallery/gallery_images/Turbomachines/JAC_FullAnnulus2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V6F9g.jpg&quot; alt=&quot;CFD picture from a compressor cascade simulation&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, these rules apply for compressor airfoils:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They should not block the flow path, so their thickness is minimized.&lt;/li&gt;&#xA;&lt;li&gt;Their angle of attack range is small, so they do not need a big nose radius.&lt;/li&gt;&#xA;&lt;li&gt;They must produce the maximum flow deflection possible, so their camber is higher than that of most wing airfoils.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The closest thing to a compressor airfoil you can find on a wing is the airfoil of a Fowler flap. Like the compressor blade, it sees almost no angle of attack variation, can be made thin because it is supported every few meters, and needs to produce as much lift as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that due to the rotation, any buildup of a thicker boundary layer is prevented by centrifugal forces, which will eject that boundary layer outwards. This allows to use more camber.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-11-18T20:55:13.730" LastActivityDate="2017-11-18T20:55:13.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13194" PostTypeId="2" ParentId="8308" CreationDate="2015-03-11T23:27:43.457" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can an aircraft cabin have a lower pressure than outside&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, absolutely is CAN.  It's not desirable, but if the seals are all tight enough &amp;amp; you descend quickly enough, it can happen.  Because the effects on the structure would be bad, aircraft typically have a negative pressure relief valve to &lt;strong&gt;&lt;em&gt;prevent&lt;/em&gt;&lt;/strong&gt; this from happening.  By definition, you don't need to prevent something that can't happen, so yes, a negative pressure differential is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you want to avoid, and with modern pressurization controllers, you probably can't reach, is a situation where you descend quickly enough to &quot;catch the cabin&quot; and the cabin altitude matches the aircraft altitude.  (Which is to say, you're depressurized -- with or without the negative pressure relief valve opening -- a few thousand feet above the ground.)  At that point (assuming you're still descending quickly), the cabin rate goes from something mild, a couple hundred feet-per-minute, to something much greater, perhaps a couple thousand feet-per-minute.  If you aren't used to dealing with that sort of a rate of change, it is disconcerting &amp;amp; uncomfortable, and for somebody who is flying with a minor head cold who could keep up with a gentle rate of change, it could be pretty painful.  And since nobody wants to scare Grandma, this is undesirable!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully, with modern pressurization controllers, you probably won't ever get there -- they'll manage the rate to keep things on schedule regardless.  With an older analog controller, it's possible, although probably pretty rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As explained in other answers, the modern controllers start to pressurize so that the cabin altitude goes slightly below the airport elevation (i.e. the cabin pressure rises slightly) at some point before liftoff (when throttles are first advanced, typically -- it's all automatic).  And on landing the cabin is likewise slightly pressurized, and that pressure bleeds off slowly after you have weight-on-wheels.  This is done so that the system transitions into and out of pressurization gradually, instead of immediately upon liftoff or on landing.  The outflow valve moving at full speed can give you a pretty good &quot;pop,&quot; and that's not comfortable, so gradual transitions are designed in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's all about keeping the paying passengers comfortable &amp;amp; happy!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-11T23:27:43.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13195" PostTypeId="2" ParentId="64" CreationDate="2015-03-11T23:35:47.277" Score="7" Body="&lt;p&gt;Specifically on Logo Lights:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're useless during the day, but they make the aircraft much easier to see from the side at night, both when taxiing and in flight.  Different carriers will have different rules; one such rule is at night + below 18,000': logo light on.  Above 18,000' and/or during the day, logo light off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the greatest benefit to the Logo Light is when crossing a runway -- gives dramatically more lit-up surface for somebody at the 3 or 9 o'clock position to see (i.e. the pilot who is on the runway that you're crossing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That, and it's nice marketing to see all your company's aircraft sitting next to each other at their gates, tails all lit up &amp;amp; looking pretty!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-11T23:35:47.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13196" PostTypeId="2" ParentId="13192" CreationDate="2015-03-11T23:46:47.093" Score="6" Body="&lt;p&gt;The only reference I could find is &lt;a href=&quot;http://www.redbullairrace.com/en_US/video/pilots-keep-throttle-full-racing&quot; rel=&quot;noreferrer&quot;&gt;here (watch the video too)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Pilots keep throttle on full for racing.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is a race. Only the fastest one wins.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-11T23:46:47.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13198" PostTypeId="2" ParentId="13184" CreationDate="2015-03-12T03:26:21.480" Score="28" Body="&lt;p&gt;There is &lt;a href=&quot;http://cryptome.org/eyeball/af1-rescue/af1-rescue.htm&quot; rel=&quot;noreferrer&quot;&gt;page by cryptome&lt;/a&gt; with documentation about AF1 rescue options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &quot;&lt;a href=&quot;http://www.0x4d.net/files/AF1/R11%20Segment%209.pdf&quot; rel=&quot;noreferrer&quot;&gt;TECHNICAL ORDER 00-105E-9, 1 FEBRUARY 2006, REVISION 11.&lt;/a&gt;&quot; (15 April 2006), slide 71 &quot;AIRSTAIR OPERATION VC-25A&quot;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_VC-25&quot; rel=&quot;noreferrer&quot;&gt;Boeing VC-25&lt;/a&gt; has only two exits equipped with own airstairs, only at doors from lower compartments. Doors at main deck have no integrated airstairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RtOuH.jpg&quot; alt=&quot;AIRSTAIR OPERATION VC-25A Boeing&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://cryptome.org/eyeball/af1-rescue/af1-rescue-08.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First photo in the question shows forward airstairs operation, and there is &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Air_Force_One_June_12_2006.jpg&quot; rel=&quot;noreferrer&quot;&gt;photo of aft airstairs&lt;/a&gt;, used in 2006.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://cryptome.org/eyeball/af1-rescue/af1-rescue-06.jpg&quot; rel=&quot;noreferrer&quot;&gt;this slide&lt;/a&gt; from the same PDF, there are 5 pairs of entry doors on main deck by design of the Boeing 747-200 plane; but 3 or them (1R, 3L, 3R) are blocked on VC-25 and can't be used. All doors from main deck have no own retractable stairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, from &lt;a href=&quot;http://people.howstuffworks.com/air-force-one4.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unlike a normal 747, the plane has its own retractable stairways, for the rear entrance and the front entrance. These &lt;em&gt;stairways open onto the &lt;strong&gt;lower deck&lt;/em&gt;&lt;/strong&gt;, and crew members and staff climb &lt;em&gt;internal staircases&lt;/em&gt; to get to the upper decks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1407" LastEditorUserId="1407" LastEditDate="2015-03-12T14:25:29.593" LastActivityDate="2015-03-12T14:25:29.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13199" PostTypeId="1" CreationDate="2015-03-12T04:52:30.260" Score="3" ViewCount="2298" Body="&lt;p&gt;I have been intrigued by this new airliner, especially about the engine. Can anyone tell me how much pressure is the compressor given by the Boeing 787 and how it can be calculated?&lt;/p&gt;&#xA;" OwnerUserId="7600" LastEditorUserId="65" LastEditDate="2015-03-12T13:18:31.157" LastActivityDate="2015-03-12T22:43:23.740" Title="How much pressure does the compressor of an engine of B787 exert on air?" Tags="&lt;airliner&gt;&lt;aircraft-performance&gt;&lt;jet-engine&gt;&lt;boeing-787&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13200" PostTypeId="2" ParentId="13199" CreationDate="2015-03-12T07:11:25.377" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Engines&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; will tell you that two engines are offered for the 787, namely the General Electric &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;nofollow&quot;&gt;GEnx&lt;/a&gt; and the Rolls-Royce &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot; rel=&quot;nofollow&quot;&gt;Trent 1000&lt;/a&gt;. Their &lt;a href=&quot;http://en.wikipedia.org/wiki/Overall_pressure_ratio&quot; rel=&quot;nofollow&quot;&gt;overall compression ratios&lt;/a&gt; are given as 52:1 for the Trent 1000 and 41:1 for the GEnx.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, however, that this just one point which will change over the whole operating envelope. In case of the Trent 1000, the point is given as &quot;top of climb&quot;, whereas the number for the GEnx is given without context. At high speed, the intake will already raise the pressure at the compressor entry by approximately 20%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we now assume that ambient pressure at the (not specified) top-of-climb altitude is a quarter of sea level pressure and add the intake pressure increase, the total pressure of the air inside the engine at the compressor exit of the Trent 1000 is 1,580,000 Pascal or 15.6 times sea level pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the static case (at rest, on the ground), the engine needs to actively suck in air, so the pressure at the compressor entry is lower than ambient (approximately 88% of ambient pressure). If we now assume that the compression ratio is around 45, the absolute pressure at the compressor exit would be 4,012,500 Pascal or 40 times sea level pressure.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-12T22:43:23.740" LastActivityDate="2015-03-12T22:43:23.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13201" PostTypeId="2" ParentId="2671" CreationDate="2015-03-12T10:08:25.940" Score="9" Body="&lt;p&gt;This question is about 1 year old and already has good answers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I like to track my flights with the GPS module of my mobile, which also records altitude. I'd like to share the data of a short haul flight, which also shows the effect:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0HXWm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After takeoff at 1:00, the first &quot;funny-stomach-drop&quot; occured after just 1 minute and 500m above ground, another at 5:00 and 3500m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is as said, the aircraft did not fall all the time. The climb rate just decreased to a lower, still positive value for a moment. This causes the same feeling like an upwards moving elevator, which stops at a certain floor.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2015-03-12T10:08:25.940" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13202" PostTypeId="1" AcceptedAnswerId="13267" CreationDate="2015-03-12T11:00:09.943" Score="7" ViewCount="690" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/12979/why-did-upward-turning-propellers-in-the-f-82-twin-mustang-cause-a-loss-of-lift&quot;&gt;this question&lt;/a&gt; the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang#Design_and_development&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article&lt;/a&gt; of the F-82 Twin Mustang is quoted. In the third paragraph of the article it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this arrangement both propellers would turn upward as they approached the center wing, which in theory would have allowed better single-engine control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There was a comment in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12979/why-did-upward-turning-propellers-in-the-f-82-twin-mustang-cause-a-loss-of-lift&quot;&gt;the other question&lt;/a&gt; that questioned this statement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;according to that article, an outward-spinning engine configuration is better in theory. i don't see how this would be. in a single-engine&#xA;  scenario, wouldn't the working engine torque push the non-working&#xA;  engine side down?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A spinning propeller should also produce more lift on the wing section behind it as it is increasing the airflow over that section. Forgetting about the torque for a second, this would already push the other wing (with the failed engine) down.&#xA;[EDIT: As answered in the comments, the lift generally has way more effect then the torque.]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So what exactly makes it more favorable to have a outward-spinning configuration in theory?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Also: Does this only apply to this aircraft, or is it valid in general?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does it say that the outward-spinning engine configuration is better in theory? What am I missing?&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-16T22:45:15.130" Title="Why is an outward spinning propeller better in theory on the North American F-82 Twin Mustang?" Tags="&lt;aerodynamics&gt;&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13204" PostTypeId="1" AcceptedAnswerId="13206" CreationDate="2015-03-12T13:28:43.727" Score="38" ViewCount="82654" Body="&lt;p&gt;I have seen references to &quot;FL180&quot; and &quot;FL300&quot;, and I know that they stand for Flight Level 180 and Flight Level 300. I've also seen references to &quot;an altitude of 18000ft&quot; or &quot;an altitude of 30000ft&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between &lt;em&gt;flight level&lt;/em&gt; and &lt;em&gt;altitude&lt;/em&gt;, how do they relate to each other, and when and why would one be used instead of the other?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="946" LastEditDate="2015-03-12T20:25:51.450" LastActivityDate="2020-12-19T18:42:54.360" Title="What is the difference between &quot;flight level&quot; and &quot;altitude&quot;?" Tags="&lt;terminology&gt;&lt;altitude&gt;&lt;flight-level&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13205" PostTypeId="2" ParentId="13204" CreationDate="2015-03-12T13:35:06.927" Score="12" Body="&lt;p&gt;FL180 and FL300 stand for Flight Level 180 and Fight Level 300. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight levels are spaced 100ft apart on an altimeter that is set to the standard sea level pressure (QNE) of 1013.25 hectopascals or 29.92 inches of Mercury. So indeed, FL300 means 30,000 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Altitude 18000 means that the altimeter indicates 18,000 feet and that the altimeter is set to the QNH, which is the pressure reading on the ground corrected to sea level pressure using the standard atmosphere. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is a low pressure area, the QNH will be lower then 1013.25 hPa. When you compare two altimeters; the first set to QNH &amp;lt; 1013.25 hPa and the second one is set to the standard setting of 1013.25, the first altimeter will indicate a lower value than the second altimeter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;QNH setting is used at lower altitude where obstacle and terrain clearance are important. But for long distance traffic it is a nuisance to change the altimeter setting as the aircraft flies through different pressure areas on the ground. Therefor the Flight Level concept was introduced, allowing everybody on higher altitude to use the same setting. This also reduces the chance that aircraft have a different altimeter setting in the same airspace, which would cause vertical separation problems. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1696" LastEditDate="2015-03-12T17:10:06.487" LastActivityDate="2015-03-12T17:10:06.487" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13206" PostTypeId="2" ParentId="13204" CreationDate="2015-03-12T13:51:11.453" Score="42" Body="&lt;p&gt;Flight levels use &lt;a href=&quot;https://en.wikipedia.org/wiki/Pressure_altitude&quot; rel=&quot;noreferrer&quot;&gt;QNE&lt;/a&gt; or pressure altitude, while altitude references &lt;a href=&quot;https://en.wikipedia.org/wiki/QNH&quot; rel=&quot;noreferrer&quot;&gt;QNH&lt;/a&gt; or local pressure adjusted to sea level pressure.  Altitudes are used at low levels and flight levels at higher levels.  The transition between altitudes and flight levels differs by country and is generally just above the highest obstacle in that country.  In the US the transition altitude/level is 18,000' / FL180.  Some countries transition as low as 5000' / FL050 and the transition altitude/level may vary from airport to airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the altitudes knowing accurate elevations relative to the ground and obstacles is important for collision avoidance and this is the reason QNH is used here.  Each airport will report QNH and controllers will issue the current QNH as needed.  You need to know the QNH for obstacle / terrain avoidance but you need to be using the same QNH as those around you for aircraft vertical separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above all terrain/obstacles the only thing we care about is vertical separation, so we no longer need to know about the actual pressure and instead use a standard reference pressure, QNE / 1013.25 hPa / 29.92&quot; Hg.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that flight levels drop the last two zeros of the corresponding altitude and so 30,000 is FL300, not FL30000.  When checking in with a controller, FL300 would be pronounced &lt;code&gt;flight level tree zero zero&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also worth noting that an altimeter cannot actually determine altitude.  It can only determine pressure (technically local static pressure compared to a reference pressure).  It converts this pressure to an altitude using a calibrated non-linear scale.  To illustrate the point, look at this map of 500 mb heights:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CbYKc.gif&quot; alt=&quot;US Map of 500 mb Geopotential Height&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;500 mb correlates to 5500 m or 18,000 ft in a standard atmosphere.  In a real atmosphere this height varies and is not actually level.  An airplane flying &quot;level&quot; at FL180 from LAX to NYC last night will have actually descended almost 300 m while indicating a constant altitude.  These deviations in true altitude from indicated altitude are acceptable, however, since they effect everyone equally in the same locality and separation is maintained.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="1696" LastEditDate="2015-03-18T22:26:29.507" LastActivityDate="2015-03-18T22:26:29.507" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13207" PostTypeId="2" ParentId="13204" CreationDate="2015-03-12T13:52:28.650" Score="7" Body="&lt;p&gt;&lt;strong&gt;Altitude&lt;/strong&gt;&lt;br&gt;&#xA;The vertical distance of an object measured from mean sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Level&lt;/strong&gt;&lt;br&gt;&#xA;To understand a flight level, we should understand how altitude is measured in an altimeter, which is essentially a calibrated barometer - it measures air pressure, which decreases with increasing altitude. To display correct altitude, a pilot re-calibrates&lt;sup&gt;1&lt;/sup&gt; the altimeter from time to time, according to local air pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight levels solve this problem by defining altitudes based on a standard pressure of 1013.2 mb (29.92 inches Hg). All aircraft operating on flight levels calibrate to this same standard setting regardless of the actual sea level pressure. Flight levels are then assigned a number which is the apparent altitude (&quot;pressure altitude&quot;) to the nearest thousand feet, divided by one hundred. Therefore an apparent altitude of 18,000 feet is referred to as Flight Level 180. &lt;em&gt;Note that aircraft may be at some other actual height than 18,000 feet, but since they all agree on a standard pressure, no collision risk arises.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight levels are not used close to the ground, for perhaps obvious reasons - obstacles are fixed to the ground and so their absolute height needs to be known. The altitude of the lowest flight level varies from country.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: Re-calibration of altimeter is done to avoid airplanes flying at the same height, though their altimeters show different altitudes. This is safety issue.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-12T13:52:28.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13208" PostTypeId="2" ParentId="13132" CreationDate="2015-03-12T16:23:38.650" Score="8" Body="&lt;p&gt;Just for completeness, there's also the B-52, which has &quot;bicycle&quot; landing gear (both the front and rear are considered &quot;main&quot; landing gear). I believe the ideal when landing it is to have the front and rear gear touch down simultaneously&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For any who care, here's a &lt;a href=&quot;https://www.youtube.com/watch?v=sSIGd6COFb8&quot; rel=&quot;nofollow noreferrer&quot;&gt;video of a B-52 landing&lt;/a&gt;, showing the nearly simultaneous touch-down of front and rear gear.&#xA;As an interesting aside, to support crabbed cross-wind landings, both the front &lt;em&gt;and&lt;/em&gt; rear main gear of the B-52 are steerable, so it can land (or take off, taxi, etc.) with the nose turned up to 15 degrees from the direction of movement. Here's another (from the front) showing a &lt;a href=&quot;https://www.youtube.com/watch?v=TCUHQ_-l6Qg&quot; rel=&quot;nofollow noreferrer&quot;&gt;crabbed landing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&#xA;1. I originally wrote that as &quot;all the gear&quot;, but that would be false. It also has tip protection gear that normally touch down quite a bit later. Its wings are quite flexible, so the tip protection gear don't normally touch down until it slows down enough that the wings are producing substantially less lift. If it's carrying a light fuel load, they might not touch even then.&#xA;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&#xA;Just when sitting still on the ground, the B-52's wings could/did flex by around 10 feet at the tip, depending on fuel load. In flight, they could flex upward still more for a total of around 17 feet of flex (over a wing span of roughly 165 feet).&#xA;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="4021" LastEditorUserId="4021" LastEditDate="2018-01-21T07:21:27.947" LastActivityDate="2018-01-21T07:21:27.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13209" PostTypeId="1" AcceptedAnswerId="13210" CreationDate="2015-03-12T17:16:34.540" Score="9" ViewCount="6517" Body="&lt;p&gt;I'm told that, depending on the heading of your aircraft, you have to fly at particular altitudes.  Which, of course, makes sense because having planes flying in opposite directions at the same altitude is just asking for a mid-air collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is this though:  What about when you are changing your heading?  Pretend, for example, that for some reason you need to go the exact opposite direction (so, we were going due west, but now we are going due east, for example.)  I know you have to gain or lose 1000ft.  But do you change altitude after the heading change, before, or during?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So: What's the proper procedure for changing altitude when you change headings?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus points:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this made more complicated if you are flying Visual Flight Rules instead of Instrument Flight Rules?&lt;/li&gt;&#xA;&lt;li&gt;Are all these rules thrown out the window in Class B and C controlled airspace?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="65" LastEditDate="2015-03-12T17:59:45.910" LastActivityDate="2015-04-07T23:30:27.497" Title="What is the proper procedure to change altitude when changing heading?" Tags="&lt;navigation&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13210" PostTypeId="2" ParentId="13209" CreationDate="2015-03-12T17:39:17.407" Score="11" Body="&lt;p&gt;&lt;strong&gt;TL;DR:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do you change altitude after the heading change, before, or during? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When flying under Air Traffic Control, you are expected to execute instructions after you receive them, following the motto &lt;code&gt;Aviate, Navigate, Communicate&lt;/code&gt;. When receiving a turn and climb instruction at the same time, you are expected to start both, e.g.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; DELME, turn left heading 220, descend FL80&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What's the proper procedure for changing altitude when you change headings? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You do not change altitude or flight level on your own when flying IFR. When flying VFR, you should adhere to the semi-circular rules when changing your direction and end up in one of the semi-circular areas. On turn techniques that allow direction change and altitude change at the same time, see &lt;a href=&quot;https://aviation.stackexchange.com/a/13211/572&quot;&gt;Tyler's answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this made more complicated if you are flying Visual Flight Rules instead of Instrument Flight Rules?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes and No, because remember: You do not change altitude or flight level without being cleared or instructed to do so when flying IFR. Whether having to choose the correct altitude or flight level when flying VFR is more difficult than having ATC select one for you, is debatable.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Additional Information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule you are talking about is the &lt;a href=&quot;http://www.eos.tuwien.ac.at/Oeko/Teaching/Theses/dissschild/id188.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;semi-circular flight level rules&lt;/a&gt;, which depending on the country, can either be applied West to East or North to South. Let's assume the example you have already used and differentiate between westbound and eastbound flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/D9u2T.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.eos.tuwien.ac.at/Oeko/Teaching/Theses/dissschild/id188.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;TU Wien&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above picture shows that aircraft on a eastbound general track between &lt;code&gt;000°&lt;/code&gt; and &lt;code&gt;179°&lt;/code&gt; are bound to odd flight levels, such as FL210, FL230, FL250, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Opposite traffic on a general track between &lt;code&gt;180°&lt;/code&gt; and &lt;code&gt;359°&lt;/code&gt; is bound to even flightlevels, such as FL220, FL240, FL260, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This flight level you are bound to use is also the flight level you request in your flightplan, called the &lt;em&gt;Requested Flight Level&lt;/em&gt; or &lt;strong&gt;RFL&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine you have a flight going westbound and you have requested FL280 as your cruise level. You would maintain this flight level until you are cleared to descend by ATC. Even if a portion of the descent or arrival route leads in the opposite direction of your orignal track, it will be ATC who is responsible to assign the correct desend flight level, but these do not have to be necessarily following the semi-ciruclar flight level rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one scenarion where a pilot may want to initiate a flight level change due to changing jurisdiction and use of the semi-circular flight level rules, which is when crossing borders between countries that use west-east and north-south rules. If are on a westbound flight (approx track: &lt;code&gt;200°&lt;/code&gt; that requires even flightlevels, such as FL280 and cross the FIR border into a country with north-south rules that require an odd flight level, you would have a step climb or descent in your flightplan to accomodate this, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;[...] FIXXA UZ123 CROSS/N0265F290 UZ123 FIXXB [...]&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;It would still be ATC who clears you to climb to FL290 at that fix, but this way your flightplan is in accordance to local semi-circular flight level rules. Remember that when flying IFR, you never change the altitude or flightlevel unless you have been instructed or cleared to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same semi-circular flight level rules apply to VFR, just with the added 500ft to stay clear of the IFR flight levels. In most cases however, VFR does not entirely follow these rules, as the are VFR and their separation is based on visual identification and the see-and-avoid principle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not familiar with airspace class B procedures, but in class C airspace, you require permissions to enter the airspace and will thus be assigned restrictions, which can be either a single altitude or flight level, an upper or lower restriction or a level or altitude band. If you are assigned either of the two latter options, you could apply the semi-circular flight level rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See below on an overview how other countries handle these semi-circular rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ybrXo.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.deltava.org/thread.do?id=0xf2ba&quot; rel=&quot;nofollow noreferrer&quot;&gt;Delta Virtual Airlines&lt;/a&gt; - Not for real navigational use)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also these related questions:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/13204/572&quot;&gt;What is the difference between “flight level” and “altitude”?&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/37/572&quot;&gt;What differences are there in Flight Level rules, internationally?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-03-13T13:23:18.220" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13211" PostTypeId="2" ParentId="13209" CreationDate="2015-03-12T18:00:52.490" Score="0" Body="&lt;p&gt;In general, you can turn faster than you can change altitude, so normally you would first make the turn and then focus on climbing or descending to the target altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that you can perform a climbing turn or descending turn, but usually you still have to continue adjusting altitude after the turn is complete. Sometimes you can make a climbing turn which ends up exactly 500 feet higher, so you are right on target. In that case both objectives are achieved simultaneously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is the same for both IFR and VFR and the type of airspace. When a controller gives an aircraft a new vector they do not tell the pilot how to execute the turn (other than sometimes specifying the direction left or right). For example, the controller might say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;November tree two five one zero, &lt;strong&gt;turn left&lt;/strong&gt; heading one five zero / &lt;strong&gt;fly heading&lt;/strong&gt; one five zero, climb and maintain five thousand five hundred feet&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="572" LastEditDate="2015-03-13T13:33:09.293" LastActivityDate="2015-03-13T13:33:09.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13212" PostTypeId="2" ParentId="13209" CreationDate="2015-03-12T19:40:00.877" Score="6" Body="&lt;p&gt;This answer is somewhat US-based so details may vary but I think the principles are the same everywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under VFR there's no specific procedure because you're maneuvering at your own discretion and maintaining your own separation from other aircraft visually. Even if there was a specific procedure - let's say it's climb first, then turn - what would you do if that procedure took you straight through a cloud? Or into airspace that requires a clearance? There are far too many possible variables, so it's always left up to the pilot to determine the safest path of flight under VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under IFR you usually only make heading and altitude changes as instructed by ATC, meaning the issue doesn't arise, with (at least) two exceptions. First, you may be operating &lt;a href=&quot;https://aviation.stackexchange.com/q/8628/62&quot;&gt;VFR-on-top&lt;/a&gt; but in that case you're effectively operating VFR and the previous remarks apply. Second, you may be on a &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;cruise&lt;/a&gt; or block clearance and then you can climb and descend as you want anyway (with some restrictions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for class B and C airspace, in theory the cruising altitude rules apply everywhere above 3000'agl (in the US) but in those airspaces you're &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0302.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;required to be in contact with ATC&lt;/a&gt; and their instructions will take precedence anyway.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-07T23:30:27.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13213" PostTypeId="1" CreationDate="2015-03-13T02:17:21.647" Score="11" ViewCount="1881" Body="&lt;p&gt;I am reading a table explaining how to plan multiple diversion returns from an individual station:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;widebody gate departures - xx minutes &lt;/li&gt;&#xA;  &lt;li&gt;narrow body gate departures - xx minutes &lt;/li&gt;&#xA;  &lt;li&gt;all hard stand departures - xx minutes&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not a native English speaker and do not understand what a &quot;hard stand departure&quot; is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could anybody please explain this term?&lt;/p&gt;&#xA;" OwnerUserId="7622" LastEditorUserId="1467" LastEditDate="2015-04-16T14:16:27.783" LastActivityDate="2015-04-16T14:16:27.783" Title="What does a &quot;hard stand departure&quot; mean?" Tags="&lt;terminology&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13214" PostTypeId="2" ParentId="13213" CreationDate="2015-03-13T02:51:01.470" Score="14" Body="&lt;p&gt;A hardstand is a type of parking spot separate from the terminal.  Wide/narrow body gates are associated with the connection to the terminal, where a hardstand is just an area of pavement reinforced for heavy vehicles (or airplanes). &lt;/p&gt;&#xA;" OwnerUserId="302" LastActivityDate="2015-03-13T02:51:01.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13215" PostTypeId="2" ParentId="13093" CreationDate="2015-03-13T03:03:42.457" Score="5" Body="&lt;p&gt;I think a few things need to be examined here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The type of flying.  A commercial aircraft is closer to a military C-17 than a B-52 or F-16 in how it is used.  It has several stops throughout the day for loading and unloading.  The maintenance in between stops does not need to be very extensive - because it has just landed, presumably working fine, the things that need to be checked primarily involve what has the most chance of decaying during a flight (tires, oil, general wear and tear, etc).  Fighters/bombers don't generally fly several legs in a day.  Fighters might double/triple turn, and in between each of these flights the maintenance inspection is a much lower requirement than between each day of flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Component Requirements.  Supersonic jet engines need maintenance more often than high bypass commercial engines.  They are stressed much more, and work on a much tighter margin of error, thus fighter/bomber aircraft need maintenance more often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Age.  Military fighter/bomber aircraft are on average much older than the average commercial aircraft.  B-52's are from the 50's, and B-1's are from the 80's (along with most of the fighter fleet).  Older aircraft require more maintenance, and there is no avoiding it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between fighters and bombers, they each have different flying styles.  Fighter engines work a lot harder than bomber engines (except the B-1, which essentially has the same engine as an F-16), and thus require maintenance more often.  Bombers are much larger, and have more systems that can break.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: Incorporating a suggestion from the comments below, it is probably useful to specifically mention a few more specific maintenance items unique to combat aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Ejection Seats:  Most military combat aircraft carry ejection seats, which have a very specific maintenance routine.  This may include repacking the associated parachute, and checking to ensure that all components are functional/in good repair.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Weapons:  The obvious difference between fighters/bombers and commercial airliners is that they carry weapons.  This means that there is a software package that needs to be maintained (that controls the weapons), the aircraft hardware needs to be maintained (ie bomb bays, missile racks, hard points, etc), and the weapon itself requires building/deconstruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Flight Computer:  Combat aircraft often have tactically specific functions in their flight computer that a commercial airliner would not.  There are routines to help calculate bomb trajectory, to link with other combat aircraft and many other military specific tasks that a commercial airliner would not need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would agree with an earlier statement stating that performance has a slightly higher emphasis than reliability in military aircraft than in commercial aircraft.  It's easy to see how the requirement to carry bombs/missiles increases aircraft gross weight, which lowers fuel efficiency.  Every internal bomb bay could potentially be a fuel tank extending range.  Hard points, even when bombs aren't installed, cause drag lowering performance.  In the end, designers have to determine which capability is more important - endurance, payload, power, etc.  You may want to install a triply redundant INS in a fighter aircraft, but you're adding weight that decreases performance, and taking space which could be devoted to other avionics (like radar).  &lt;/p&gt;&#xA;" OwnerUserId="302" LastEditorUserId="302" LastEditDate="2015-03-18T13:28:27.990" LastActivityDate="2015-03-18T13:28:27.990" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13216" PostTypeId="1" AcceptedAnswerId="13217" CreationDate="2015-03-13T03:25:34.223" Score="3" ViewCount="1343" Body="&lt;p&gt;Specifically, when is it legal to turn to your on-course heading?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find that sometimes the tower will give me an instruction to &quot;turn on course&quot; but sometimes they don't. Are you supposed to stay on the runway heading when you do not get the instruction to turn on course, or do you just go ahead and turn after reaching some altitude?&lt;/p&gt;&#xA;" OwnerUserId="7601" LastEditorUserId="65" LastEditDate="2015-03-13T12:21:43.910" LastActivityDate="2015-03-14T02:20:53.147" Title="When departing from a class C or D airfield, what is the proper VFR procedure?" Tags="&lt;visual-flight-rules&gt;&lt;class-d-airspace&gt;&lt;class-c-airspace&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13217" PostTypeId="2" ParentId="13216" CreationDate="2015-03-13T05:15:51.137" Score="2" Body="&lt;p&gt;Either C or D controllers will likely accept your requested heading, which can be given as a rough compass point, on initial contact. This contact will be after picking up the terminal info on ATIS, when you contact ground.  Your preferred direction will be passed up the chain.  A class D may tell you something like &quot;cleared for takeoff, Northbound departure approved&quot;, in which case I would feel free to turn as soon as I deemed it safe.  In a class C scenario, the same thing could happen, but they might vector you around other traffic.  In all cases &quot;resume own navigation&quot; will be permission to take your heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are still on runway heading and feel you have not been given a clearance sending you where you want to go, you may contact tower or departure control, depending on whom you are with, and say something like &quot;Tower, Diamond two-eight bravo, request heading zero six zero&quot;  They may respond with an &quot;approved as requested&quot; or &quot;heading zero six zero approved&quot; or they may give you instructions to &quot;fly present heading, I'll call your turn&quot; indicating they are not ready for you to take your heading yet.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is, you can take your heading when you have been cleared to do so.  Understanding when you have been cleared is a matter of becoming familiar with standard phraseology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers I have worked with, especially at C and D airspaces have been accommodating.  Their job is to send pilots where they want to go while keeping aircraft out of each other’s way.  They have rolled along with me when I have changed my mind about landing,  I can say &quot;I changed my mind, I'd rather depart the pattern to the south&quot; but to be brief I'll say &quot;Cancel landing intention, request south departure.&quot;  As airspace gets bigger and controllers are busier (which can vary by location and even time of day) brevity becomes increasingly important.  To get practice, you can find out when an particular airspace is less busy.  Controllers have been known to be chatty when traffic volume is low, and you may even be able to ask questions about preferred phraseology.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="182" LastEditDate="2015-03-14T02:20:53.147" LastActivityDate="2015-03-14T02:20:53.147" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13218" PostTypeId="1" CreationDate="2015-03-13T09:36:29.540" Score="5" ViewCount="809" Body="&lt;p&gt;Edited question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was on an A320, asleep, around the mid-point of the flight at about 30,000ft. I suddenly heard a constant noise like someone hitting the plane from outside with a hammer. The noise wasn't too loud but it was distinct. I looked around, none of the passengers seemed perturbed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The noise continued for 10-15 minutes, stopped, then started again after another 30 minutes. I was about to bring it to the attention of the crew, but the plane had started its descent by then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know what the noise could have been? And should I have alerted the crew?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Checked the linked questions. Its not a PTU, because the noises were heard mid-flight not during take-off or landing. Also, the second part of the question, can be answered.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="19" LastEditDate="2017-03-02T16:10:33.133" LastActivityDate="2017-03-02T16:10:33.133" Title="What could cause a noise like a hammer on an A320 in flight?" Tags="&lt;airbus-a320&gt;&lt;noise&gt;" AnswerCount="0" CommentCount="9" FavoriteCount="1" ClosedDate="2019-06-06T21:56:41.587" ContentLicense="CC BY-SA 3.0" />
  <row Id="13219" PostTypeId="1" AcceptedAnswerId="13220" CreationDate="2015-03-13T10:07:47.693" Score="2" ViewCount="764" Body="&lt;p&gt;This question is from a French aeronautics exam so I translated as best I can but I suck at these terms in English. Anyways, can someone please explain this question to me because I'm just really confused by other explanations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an air stream in motion, the total pressure is equal to:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;- difference between dynamic pressure and static pressure.&#xA;- sum of dynamic and static pressures.&#xA;- difference between atmospheric pressure and dynamic pressure.&#xA;- sum of static and atmospheric pressures.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="7624" LastEditorUserId="65" LastEditDate="2015-03-13T12:18:00.680" LastActivityDate="2015-03-13T12:18:00.680" Title="What is the total pressure of an air stream in motion?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13220" PostTypeId="2" ParentId="13219" CreationDate="2015-03-13T10:26:45.137" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Total_pressure&quot; rel=&quot;nofollow&quot;&gt;total pressure&lt;/a&gt; assumes that the is an isentropic evolution from air in movement up to an static state. The total pressure is the pressure at such state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way to compute this &quot;made up&quot; variable you need to compute the static pressure and the dynamic pressure (driven by the air speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the sum of the dynamic and static pressure&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But remind that is not &quot;a real property&quot; but more a way to measure the maximum pressure that can be achieved from a fluid in movement without adding extra energy.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-03-13T10:26:45.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13221" PostTypeId="1" AcceptedAnswerId="13228" CreationDate="2015-03-13T10:50:30.557" Score="17" ViewCount="13305" Body="&lt;p&gt;I've heard pulsejet powered aircraft can fly at very fast speeds but are there any drawbacks to this type of engine? And are the disadvantages greater than the advantages or vice versa? &lt;/p&gt;&#xA;" OwnerUserId="7624" LastEditorUserId="22726" LastEditDate="2019-11-12T04:05:41.927" LastActivityDate="2019-11-12T04:05:41.927" Title="What are the pros and cons of a pulsejet?" Tags="&lt;jet-engine&gt;&lt;pulsejet&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13222" PostTypeId="2" ParentId="13221" CreationDate="2015-03-13T11:11:04.460" Score="10" Body="&lt;p&gt;First of all they are &lt;strong&gt;loud&lt;/strong&gt; there is a reason that the V1 bomb is called the &quot;buzz bomb&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also fuel hungry due to the low compression ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest advantage it that they are very simple. Once you have them ignited they will continue to burn until they run out of fuel or the airflow is disturbed.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-03-13T11:11:04.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13223" PostTypeId="1" CreationDate="2015-03-13T11:14:02.887" Score="8" ViewCount="2058" Body="&lt;p&gt;There is an old warning on mountain flying that wind flowing through a narrow valley will cause &lt;a href=&quot;http://en.wikipedia.org/wiki/Venturi_effect&quot;&gt;Venturi effect&lt;/a&gt;, thus causing a drop in static pressure and making our little Cessna fly lower than indicated, possibly hitting some hidden mountain peak. I'm certain I know the answer to this one, but I'd like to hear someone explain it better, so here is my question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You fly a Cessna 172 level at FL50 (pressure altitude) with a huge&#xA;  40kts headwind. You need to traverse a narrow valley passing between&#xA;  two huge peaks on either side. Will your airplane fly at a constant&#xA;  true altitude in a straight line, or will the Venturi effect caused by&#xA;  the wind and the valley cause our aircraft to sink while passing&#xA;  through the valley?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="65" LastEditDate="2015-03-13T12:32:36.767" LastActivityDate="2015-03-14T08:35:55.980" Title="How will flying through mountains cause altimeter problems?" Tags="&lt;aerodynamics&gt;&lt;altimeter&gt;&lt;mountain-flying&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13225" PostTypeId="2" ParentId="13223" CreationDate="2015-03-13T14:04:22.767" Score="2" Body="&lt;p&gt;From my understanding of this, the Venturi effect created in the valley will drop temperatures much like the Venturi effect causes temp drops in your carb. which you know will change pressure (increase) and thus change altimeter reading. Since you are flying at a relatively low altitude you will be affected by the change.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="774" LastEditDate="2015-03-14T03:21:41.840" LastActivityDate="2015-03-14T03:21:41.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13226" PostTypeId="2" ParentId="13221" CreationDate="2015-03-13T14:11:29.460" Score="8" Body="&lt;p&gt;Pulse jets were big during WWII but the have a few issues. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Advantages:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from throttle flaps pulse jets have essentially no moving parts which makes them not only simple to build but simple to maintain. People build them in their garages at home all the time. From a war time standpoint this was great since you could make many of them in a short time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Disadvantages:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noise: Pulse jets are much louder than their spinning counterparts. This makes them some what less useful from a stealth/wartime standpoint and from a commercial standpoint in regards to general noise pollution concerns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low Impulse: From my understanding of them pulse jets have a low specific impulse due to their more piston like ignition pattern. They don't deliver the kind of thrust their fan like counterparts can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Size: If memory serves they are also much bigger than a regular jet (for a given power output).    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-13T14:11:29.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13227" PostTypeId="2" ParentId="701" CreationDate="2015-03-13T14:20:55.437" Score="4" Body="&lt;p&gt;Another factor is fuel flow (at least in small GA planes). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets compare a Cessna 172 to a Piper Cherokee. The Piper is low wing and requires a fuel pump (engine driven with an electric backup) to flow the gas from the wing tanks up to the engine. This add not only adds another part that can fail but the possibility that you can vapor lock the system if you run it dry. In a the Cessna (high wing) the fuel is pulled by gravity, out of the wing tanks, and into the engine much like an old car (1930's era). This eliminates the fuel pump and the vapor lock issue which some people find quite nice. At this point I am well into the habit of switching tanks every 30 minutes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A note should be made that some Cessnas (from what I have read) do have fuel pumps now but I don't fly them so I don't know a lot about the newer model specifics.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;High wing airplanes also prove to be advantageous if you are flying a lot of back country stuff. The added clearance can help you land in bushy areas or other less hospitable places where a low wing plane might strike something.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best answer to this question can usually be found at your local airfield. Ask a guy that owns a Piper (just not a Cub), then ask a guy that owns a Cessna (just not the 400), and decide for your self based on their answers.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-03-13T14:32:16.960" LastActivityDate="2015-03-13T14:32:16.960" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13228" PostTypeId="2" ParentId="13221" CreationDate="2015-03-13T15:01:46.227" Score="17" Body="&lt;p&gt;The pulse jet engine works because it uses the dynamic pressure of air for compression. Consequently, it needs speed to work well. If the pulse jet is on the ground, it is not easy to start - it needs to be fed with compressed air, and once it runs (it can run even when not moving because the oscillating pressure wave inside the tube will compress the inflowing air), it develops litte thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust will go up with airspeed, so you need additional thrust sources for initial acceleration and take-off. In case of the V-1, this was done by a steam catapult or by air-launching the device. Note that the V-1 was accelerated to 370 km/h on a 45 m long catapult which means more than 100 m/s² (10g) average acceleration. Most of the development work went into making the airframe withstand this acceleration. A modern design would need additional engines as well, and once those are included, the rationale for pulse jets becomes very weak. They make sense if you have an air-launched, disposable application, such as long-range air-to-air missiles. This is a niche in which their higher-speed cousins, the ramjets, &lt;a href=&quot;http://en.wikipedia.org/wiki/Meteor_(missile)&quot; rel=&quot;noreferrer&quot;&gt;will still be used&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pros:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Very easy to build, very light.&lt;/li&gt;&#xA;&lt;li&gt;Runs and produces some thrust when at rest (as opposed to ramjets). &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cons:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thrust grows with flight speed. This can be seen as a pro, but normally requires additional means of acceleration. Therefore listed as contra here.&lt;/li&gt;&#xA;&lt;li&gt;Low fuel efficiency. The fuel energy is converted to other forms of energy: Just listen to the videos of &lt;a href=&quot;http://www.colinfurze.com/big-pulse-jet-project.html&quot; rel=&quot;noreferrer&quot;&gt;Colin Furze&lt;/a&gt; to get an idea.&lt;/li&gt;&#xA;&lt;li&gt;High levels of vibration due to the intermittent operation. When the &lt;a href=&quot;http://en.wikipedia.org/wiki/Heinkel_He_280&quot; rel=&quot;noreferrer&quot;&gt;Heinkel 280&lt;/a&gt; was tried out with &lt;a href=&quot;http://en.wikipedia.org/wiki/Argus_As_014&quot; rel=&quot;noreferrer&quot;&gt;Argus pulsejets&lt;/a&gt;, the aircraft experienced unacceptable vibration.&lt;/li&gt;&#xA;&lt;li&gt;Need heat-resistant materials. The central part will get very hot in operation, so at least nickel-chrome stainless steel is needed if air cooling is insufficient.&lt;/li&gt;&#xA;&lt;li&gt;Cannot go supersonic. For this, there are &lt;a href=&quot;http://en.wikipedia.org/wiki/Ramjet&quot; rel=&quot;noreferrer&quot;&gt;ramjets&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NACA tested the As 014 pulse jet and wrote a &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1945/naca-wr-e-269.pdf&quot; rel=&quot;noreferrer&quot;&gt;report&lt;/a&gt;, from which the performance data depicted below is taken:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PhEcZ.png&quot; alt=&quot;Thrust of the As 014 over speed&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that &lt;a href=&quot;http://aardvark.co.nz/pjet/&quot; rel=&quot;noreferrer&quot;&gt;Bruce Simpson over in New Zealand&lt;/a&gt; has improved the pulse jet design a lot: He needs no compressed air for starting and makes clever use of surrounding cold air to increase mass flow and keep material temperatures down.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-04T22:30:39.723" LastActivityDate="2015-07-04T22:30:39.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13229" PostTypeId="2" ParentId="8339" CreationDate="2015-03-13T15:47:40.243" Score="8" Body="&lt;p&gt;Having lived for nearly 15 years around the Boeing factories in Seattle, it was a common sight to see a flat-bed truck with a tarp-covered engine driving up and down the freeway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just like other big industrial machinery, they build a mounting for it, put it on a truck, and drive it down I-5.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-03-13T15:47:40.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13230" PostTypeId="1" AcceptedAnswerId="13246" CreationDate="2015-03-13T16:18:40.113" Score="2" ViewCount="1101" Body="&lt;p&gt;Are Targeted Airspeed and selected Airspeed the same thing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And can someone explain in what cases managed airspeed or pilot selected airspeed would be used, i.e. for different flight phases/situations etc.?&lt;/p&gt;&#xA;" OwnerUserId="7627" LastEditorUserId="65" LastEditDate="2015-03-13T16:26:58.873" LastActivityDate="2015-03-14T12:38:26.307" Title="What is the difference between targeted airspeed and selected airspeed?" Tags="&lt;flight-instruments&gt;&lt;autopilot&gt;&lt;pilots&gt;&lt;airspeed&gt;&lt;v-speeds&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13231" PostTypeId="1" AcceptedAnswerId="13232" CreationDate="2015-03-13T17:32:04.703" Score="22" ViewCount="4237" Body="&lt;p&gt;A quick follow-up to &lt;a href=&quot;https://aviation.stackexchange.com/questions/13132/why-do-planes-always-land-on-rear-wheels-instead-of-the-nose-wheels?noredirect=1#&quot;&gt;Why do planes always land on rear wheels instead of the nose wheels?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What airframe designer/manufacturer is credited with the first retractable landing gear system? I ran past the article on retractable gear over in Wikipedia without really finding an answer&lt;/p&gt;&#xA;" OwnerUserId="83" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-06-30T15:42:54.550" Title="What airframe designer/manufacturer is credited with the first retractable landing gear system?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13232" PostTypeId="2" ParentId="13231" CreationDate="2015-03-13T18:51:10.217" Score="28" Body="&lt;p&gt;It looks like the first plane that actually flew and had at least a partially-retractable undercarriage was a German racing plane, the Wiencziers Renneindecker, from 1911:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5lc9F.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the undercarriage designed to collapse to the rear, using a hand crank in the cockpit to lift the gear. Not a great idea by today's standards as the gear would be prone to collapse on landing, but it apparently worked well enough at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are plans for retractable landing gear dating back to the late 1800s, before powered flight in such a craft was ever achieved, but they didn't become common on planes until just after WWI. Even then, for relatively slow planes (&amp;lt;200mph) it remains common even today to keep the gear fixed and wrap the wheels in a cowl, as for only a ~4% increase in drag over a full retractable setup, you save a lot of weight and mechanical complexity. Notable fixed-gear craft in military service through WWII include the German Ju87 Stuka and the Nakajima Ki-27 &quot;Nate&quot;. Though most of the American wartime air fleet had retractable gear as of just after the start of WWII, practically every WWII air corps draftee trained on either a BT-11 or one of the biplane trainers like the PT-13/17/18. Today, plenty of civvie small craft have fixed gear, such as the Cessna 150, 172 and variants, Piper Cubs and Cherokees, some Beechcraft Musketeers, etc etc.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-30T15:42:54.550" LastActivityDate="2015-06-30T15:42:54.550" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13233" PostTypeId="1" CreationDate="2015-03-13T19:37:10.870" Score="8" ViewCount="2830" Body="&lt;p&gt;The maximum and cruise speeds listed for &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot;&gt;North American XB-70 Valkyrie&lt;/a&gt; are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Maximum speed: Mach 3.1 (2,056 mph, 3,309 km/h)&lt;/li&gt;&#xA;  &lt;li&gt;Cruise speed: Mach 3.0 (2,000 mph, 3,200 km/h)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why is there such a small difference?  &lt;/p&gt;&#xA;" OwnerUserId="7630" LastEditorUserId="62" LastEditDate="2017-05-30T17:08:11.393" LastActivityDate="2020-03-26T02:31:14.287" Title="Why is the XB-70's Top speed only about 60mph higher than its cruise speed?" Tags="&lt;airspeed&gt;&lt;supersonic&gt;&lt;bomber&gt;&lt;xb-70-valkyrie&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13234" PostTypeId="1" AcceptedAnswerId="13237" CreationDate="2015-03-13T20:12:31.667" Score="9" ViewCount="25160" Body="&lt;p&gt;For example if you look at V 23-165-597, from Seal Beach CA to Ocean Side CA, you will notice that it goes through restricted area for Camp Pendleton (R-2503A &amp;amp; D):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V57gU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was trying to understand what is the rule as far as ATC Clearance to enter those Airspace or any other Airspace in general when you are on those Victor Airways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where can I find the FAA rules about these Victor Airways?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="62" LastEditDate="2015-03-13T20:38:42.763" LastActivityDate="2016-05-31T22:15:22.277" Title="Can a pilot fly through a restricted area while flying on a Victor Airway?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13235" PostTypeId="2" ParentId="13233" CreationDate="2015-03-13T20:19:03.097" Score="9" Body="&lt;p&gt;From the excellent point in the comments, the XB-70 was designed for one thing; speed. It was, until the Blackbird, the fastest manned air-breathing aircraft. It was intended to outrun Soviet interceptors like the MiG-25 and fly higher than ground-based anti-aircraft weapons of the day, making it a possible first-strike weapon. As such, it wasn't going to loiter around at 80% throttle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second point is that since the B-70 project was cancelled for several reasons (cost projections, development of ICBMs and of high-altitude fast-tracking SAMs), the two prototypes were used primarily as testbeds to push the envelope of air-breathing craft. As such, data regarding their fuel efficiency curve was secondary to more basic problems of aircraft design for hypersonic aerodynamic flight.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-03-13T20:19:03.097" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13236" PostTypeId="2" ParentId="701" CreationDate="2015-03-13T20:51:44.503" Score="2" Body="&lt;p&gt;Let me add one more advantage/disadvantage pair.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High-wing aircraft (at least for small GA aircraft) may be easier to preflight as wing fuel drains are more accessible and it is easier to examine the underside of the wing (flap linkages, aileron hinges, skin, possible fuel leakages). Personally, I'm tall enough to be able to see the top of the wing without a ladder, but I'll admit that this advantage shrinks for shorter pilots. The downside is ease of refueling (and sticking the fuel tanks). A Cherokee (low-wing) doesn't require a ladder to refuel whereas we carry a stepladder in our club Cessnas. &lt;/p&gt;&#xA;" OwnerUserId="3211" LastActivityDate="2015-03-13T20:51:44.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13237" PostTypeId="2" ParentId="13234" CreationDate="2015-03-13T21:00:39.563" Score="14" Body="&lt;p&gt;Short answer: yes, with permission. Whether or not you're on an airway isn't really relevant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic regulations on restricted airspace are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1133&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.133&lt;/a&gt; and they apply to all aircraft on all flights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may operate an aircraft within a restricted area&#xA;  (designated in part 73) contrary to the restrictions imposed, or&#xA;  within a prohibited area, unless that person has the permission of the&#xA;  using or controlling agency, as appropriate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0304.html&quot; rel=&quot;noreferrer&quot;&gt;AIM 3-4-3&lt;/a&gt; also makes it clear that you can enter restricted airspace (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Restricted areas contain airspace identified by an area on the surface&#xA;  of the earth within which the flight of aircraft, &lt;strong&gt;while not wholly&#xA;  prohibited&lt;/strong&gt;, is subject to restrictions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And it has details of how ATC handles IFR traffic:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1. If the restricted area is not active and has been released to the controlling agency (FAA), the ATC facility will allow the aircraft to&#xA;  operate in the restricted airspace without issuing specific clearance&#xA;  for it to do so.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2. If the restricted area is active and has not been released to the controlling agency (FAA), the ATC facility will issue a clearance&#xA;  which will ensure the aircraft avoids the restricted airspace unless&#xA;  it is on an approved altitude reservation mission or has obtained its&#xA;  own permission to operate in the airspace and so informs the&#xA;  controlling facility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, you can fly through restricted airspace if the controlling agency gives you permission, either directly or via ATC. In the specific case of the Camp Pendleton restricted areas, the Los Angeles sectional says that you should contact LA Center or SoCal TRACON (for R-2503D), and shows that the areas are not active 24 hours per day:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xDynp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in theory you can fly through at 3am without asking anyone, but if you're planning a flight that goes through a restricted area you should make sure you get a flight briefing and ask the briefer about that point specifically. And it wouldn't hurt to confirm again in the air before entering, in case the areas 'go hot' suddenly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-03-13T21:00:39.563" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13238" PostTypeId="2" ParentId="13234" CreationDate="2015-03-13T21:28:20.207" Score="10" Body="&lt;p&gt;Camp Pendleton's current R-2503D zone, which extends along the California coastline to the southeast of the former Camp Pendleton MOA, is a special case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off, it can only be activated via NOTAM for a maximum of 20 days a year from 0600 to 2359, and a maximum of 90 days a year between 2400 and 0600 local time. So, for 345 days a year, you can fly right through this airspace at 2000AGL or higher, either VFR or IFR under guidance from LA Center. MCB Pendleton's airstrip remains Class D, and the majority of the remaining R-2503 airspace (including R-2503A below 2000 feet) is active 7 days a week from 0600-2359 local time, extensible by NOTAM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, when R-2503D is active, non-participating craft may still gain entry by contacting MCB Pendleton's tower, codename &quot;Longrifle&quot;, whose frequency has been released for general aviation. Clearance would be granted case-by-case based on the nature of activities within the airspace at the time; if denied, the detour for all routes through R-2503D is just offshore, within glide distance of land in most cases.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-06T15:22:21.420" LastActivityDate="2015-05-06T15:22:21.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13239" PostTypeId="1" AcceptedAnswerId="13240" CreationDate="2015-03-13T21:41:24.870" Score="10" ViewCount="2772" Body="&lt;p&gt;The FAA says that a DME ground station sends a response exactly 50 microseconds after having received an interrogation from an aircraft. For what reason is there a 50 microsecond delay?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="5517" LastEditDate="2015-03-16T20:38:41.730" LastActivityDate="2015-03-16T20:38:41.730" Title="Why does a DME ground station wait 50 microseconds?" Tags="&lt;navigation&gt;&lt;navaids&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13240" PostTypeId="2" ParentId="13239" CreationDate="2015-03-13T22:31:23.370" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;the purpose of the 50 microsecond delay is to eliminate the possibility of uncoordinated operation when the aircraft is very close to the ground station&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.avweb.com/news/avionics/183230-1.html?redirected=1&quot; rel=&quot;nofollow&quot;&gt;AVweb - DME Basics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Addendum&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not found a clear explanation for what is meant by &quot;uncoordinated operation&quot; in the context of DME. What follows is speculation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at patents related to DME, it seems this predictable delay ensured that the initial transmission from the aircraft would have been completely received before the reply was transmitted by the base-station and received at the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe a DME response has to match the pattern of the DME interrogation so that the receiver in the aircraft can identify which response to apply timing to if multiple DME-equipped aircraft are in range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pulse spacing is 12 µs&lt;sup&gt;1&lt;/sup&gt; and this is the same order of magnitude as the round-trip transmission time at 1 mile. A single DME interrogation contains several pulses. It may be difficult to design ground station equipment that can start transmitting a matching response if it has not yet received the pattern of data it has to reproduce. The alternative would be to start transmitting the response as soon as possible after detecting the end of receipt of a valid DME interrogation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are delays in processing within the ground station equipment which may vary (at least from station to station depending on equipment) and which therefore need to be made constant for accurate distances to be calculated by the airborne receiver. Any variations would be more significant at closer distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It might also be easier to design airborne equipment if it does not have to start receiving the response before it has finished transmitting the interrogation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;References&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.google.co.uk/patents/US3226714&quot; rel=&quot;nofollow&quot;&gt;US Patent 3226714&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.pprune.org/archive/index.php/t-161950.html&quot; rel=&quot;nofollow&quot;&gt;PPRuNe discussion&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I believe DME was invented around 1944-45 but cannot find any patents that early. There are quite a few patents on this subject.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-03-16T17:14:22.950" LastActivityDate="2015-03-16T17:14:22.950" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="13241" PostTypeId="2" ParentId="13239" CreationDate="2015-03-13T22:32:19.233" Score="23" Body="&lt;p&gt;The delay is not 50 &lt;em&gt;milliseconds&lt;/em&gt;, but 50 &lt;em&gt;microseconds&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It takes some time for the ground equipment to decode the incoming signal, decide it needs to reply, and fire up its transmitter. In order for the distance measurement to be reliable, this inevitable delay needs to be precisely defined and the same for all DME stations. It also gives the airborne interrogation some minimal time to shut down its transmitter and start listening even when it's right on top of the ground station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;50 µs must have felt like a suitable interval to standardize on, &lt;strong&gt;long enough&lt;/strong&gt; for it to be reasonably possible to engineer the ground stations to meet it (given the technology of the time the design was made), yet &lt;strong&gt;short enough&lt;/strong&gt; that one DME station can service an acceptable number of aircraft without needing to handle overlapping delays between different interrogations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard delay also means that a DME station used for ILS can be located midway between the runway's thresholds and adjusted such that aircraft see the distance to the threshold rather than the distance to the physical antenna, by reducing the delay appropriately. (Such a DME does not give useful readings for aircraft not aligned with the runway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, by the way, that the 50 µs is the time between receiving the &lt;em&gt;second&lt;/em&gt; pulse of an interrogation pulse-pair and transmitting the &lt;em&gt;second&lt;/em&gt; pulse of the resply. So the ground station actually has to &lt;em&gt;start&lt;/em&gt; transmitting the reply less than 50 µs after it knows it has received a complete interrogation. For Y channels where there are 30 µs between the two reply pulses, the ground station &lt;em&gt;actually&lt;/em&gt; has only 20 µs to react.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-03-14T13:45:47.137" LastActivityDate="2015-03-14T13:45:47.137" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="13242" PostTypeId="1" CreationDate="2015-03-13T23:41:53.247" Score="2" ViewCount="222" Body="&lt;p&gt;I have been seeing references to 206 ATA recently. However, it appears to be so new that very little Google indexed information is available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has anyone dealt with this particular  ATA chapter, and if so are there any publicly available resources?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Please note:&lt;/strong&gt; I am not talking about &lt;a href=&quot;http://en.wikipedia.org/wiki/USS_Pinola_(ATA-206)&quot; rel=&quot;nofollow&quot;&gt;USS Pinola (ATA-206)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7632" LastEditorUserId="65" LastEditDate="2015-03-14T14:38:50.713" LastActivityDate="2015-04-13T15:32:33.103" Title="Does anyone know of sources for ATA 206?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13243" PostTypeId="1" CreationDate="2015-03-14T01:24:11.007" Score="5" ViewCount="667" Body="&lt;p&gt;Does a new pilot who has just obtained ATPL license has job opportunities?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I search at pilot job offered on Internet, they mostly required more than 3,500+ flying hours. What I knew about those who obtained ATPL license have flying hours aroun 1500 hours. It mostly includes aviation academy training used turboprop engine plane and they are very light weight. The jobs ads require those pilot who have flown aircraft more than 40,000 lbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will a new pilot get an opportunity to get such a job? How does new pilot get their job under these kind of conditions?&lt;/p&gt;&#xA;" OwnerUserId="7633" LastEditorUserId="65" LastEditDate="2015-03-14T14:53:05.830" LastActivityDate="2017-02-07T17:35:06.657" Title="What job opportunities are there for low time pilots in Malaysia?" Tags="&lt;flight-training&gt;&lt;career&gt;&lt;airline-pilot&gt;&lt;malaysia&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13244" PostTypeId="2" ParentId="13230" CreationDate="2015-03-14T07:07:58.120" Score="1" Body="&lt;p&gt;V-Target (should be a subscript Target) is the speed you're going to maintain flying down final in the landing configuration.  Your &lt;em&gt;selected&lt;/em&gt; airspeed is where you have the cursor right now, so as you go from cruise at say .78 mach to a descent at 280 knots to the descent below 10,000' at 250 knots, to slowing in the pattern to 200 or 210 knots, then configuring with various flap settings, your selected speed changes to each of those, until you've extended the last increment of flaps, and you &quot;set Target&quot; in the window (so that's where your speed cursor goes on the airspeed indicator or tape), and now the Target speed is your selected speed as you fly down final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might simplify that explanation to, Target is what you WILL set to fly the final approach in landing configuration, while your Selected speed is what you have selected right now.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-14T07:07:58.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13245" PostTypeId="2" ParentId="107" CreationDate="2015-03-14T07:27:31.657" Score="2" Body="&lt;p&gt;In &quot;full up&quot; FMC/VNAV/Autothrottle airplanes, Level Change tends to be an &quot;all or nothing&quot; option for power: full climb power to go up, and flight idle to come down (with pitch holding the commanded speed in both cases).  With Vertical Speed, the pitch holds your climb rate constant, and the throttles vary to hold your airspeed.  With a sufficiently large V/S value commanded, you reach either full climb thrust or flight idle, and then the throttle can't affect airspeed any more -- so you can lose airspeed with a steep climb commanded, or gain it with a steep descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then at some point, you look up &amp;amp; wonder why we're so fast/slow, and realize that V/S has done you in, and you go back to flying the airplane.  :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason that I personally prefer V/S over level change in certain circumstances is that the latter tends to be fairly aggressive about maintaining speed, so in gusty conditions the autopilot (in level change) will end up pushing &amp;amp; pulling quite a bit to hold the speed +/- a knot or two.  I think that tends to be an uncomfortable ride, so I'll go to V/S and let the speed fluctuate (the autothrottles can chase it, or I deselect them &amp;amp; just leave a stable power setting) while the pitch attitude stays constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point, you go back to a speed mode (i.e. once you level off), but for the stable pitch instead of constant push/pull/push/pull, V/S has its advantages.  Just don't ignore it long enough to let your speed do undesirable things to you!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-14T07:27:31.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13246" PostTypeId="2" ParentId="13230" CreationDate="2015-03-14T08:17:06.843" Score="2" Body="&lt;p&gt;These terms obviously stem from an Airbus flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything &lt;strong&gt;selected&lt;/strong&gt; represents pilot's discretion. If you want to keep a certain speed, HDG or altitude, you would &lt;strong&gt;pull&lt;/strong&gt; the corresponding FCU (Flight Control Unit = Autopilot Panel) knob. This means in Airbus philosophy: I have control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything &lt;strong&gt;managed&lt;/strong&gt; represents a flight management calculation. If you want to fly, e.g. in the most economic way, you &lt;strong&gt;push&lt;/strong&gt; the corresponding FCU knob and therewith &quot;handover the controls to the aircraft&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The calculations for managed autopilot options are derived from e.g. gross weight entries on the INIT page or current gross weight, Angle of Attack, Air Data Computers, Cost Index, ... depending on the flight phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, you always prefer to follow the economically calculated way and use managed modes. Whenever ATC requests you to keep a certain speed, sink/climb rate, heading whatever, you pull the knobs and select the target values.&lt;/p&gt;&#xA;" OwnerUserId="968" LastEditorUserId="65" LastEditDate="2015-03-14T12:38:26.307" LastActivityDate="2015-03-14T12:38:26.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13247" PostTypeId="2" ParentId="13223" CreationDate="2015-03-14T08:35:55.980" Score="3" Body="&lt;p&gt;You basically answered the question yourself already.&#xA;Venturi states: the sum of pressures in a system stays constant.&#xA;The system is the valley and the pressures are the air (static pressure) within the valley and the wind flowing through it (dynamic pressure).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static Pressure + Dynamic Pressure = Total Pressure&#xA;If the wind flows faster, we got higher dynamic pressure. Since the sum stays constant the static pressure has to fall as a consequence.&#xA;Of course, then, all pressure levels shrink under lower static air pressure as they would do under cold temperatures. Flying at a constant pressure level results in following these shrinking levels and eventually end up at a lower true altitude.&#xA;That's the main reason why your true altitude is lower than your indicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you knew the actual static pressure in the valley, you could adapt your altitude by the rule of thumb: per 1hPa: 30ft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So answering your question: if the venturi effect reduces static air pressure in the valley, the above stated applies.&lt;/p&gt;&#xA;" OwnerUserId="968" LastActivityDate="2015-03-14T08:35:55.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13248" PostTypeId="1" AcceptedAnswerId="13249" CreationDate="2015-03-14T11:28:02.963" Score="38" ViewCount="2423" Body="&lt;p&gt;Los Angeles KLAX and Casablanca GMMN (Morocco) are &lt;a href=&quot;https://www.google.com/maps/@31.6700255,-57.1573496,4z&quot; rel=&quot;noreferrer&quot;&gt;at the same latitude&lt;/a&gt;. &#xA;If the aircraft follows a magnetic 090° heading, the initial &lt;a href=&quot;http://www.gcmap.com/airport/LAX&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;true&lt;/em&gt; heading will be 102°&lt;/a&gt; due to the declination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NqpPS.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NqpPS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(source &lt;a href=&quot;http://alabamamaps.ua.edu/contemporarymaps/world/world/world1c.jpg&quot; rel=&quot;noreferrer&quot;&gt;University of Alabama&lt;/a&gt;.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means the path will start slightly southerly.&lt;br&gt;&#xA;What will be the path followed until reaching a continent on the other side of the Atlantic?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-08-13T13:02:21.217" LastActivityDate="2020-07-26T10:37:25.920" Title="Where do I land if I fly from KLAX with a constant east heading, crossing the US and the Atlantic ocean?" Tags="&lt;navigation&gt;&lt;magnetic-variation&gt;&lt;heading&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13249" PostTypeId="2" ParentId="13248" CreationDate="2015-03-14T14:03:34.110" Score="64" Body="&lt;p&gt;If an aircraft is following a magnetic course changes in magnetic declination as the aircraft moves along its route of flight will affect the true course, and on a long flight such as the hypothetical trip posed here we need to take that into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Magnetic declination is empirical data, i.e. there are tables of it, and &lt;a href=&quot;https://aviation.stackexchange.com/a/273/64&quot;&gt;while formulas exist&lt;/a&gt; to approximate it you would normally use the reference tables. There are several sources of data for the worldwide declination of the magnetic field, for example &lt;a href=&quot;http://www.ngdc.noaa.gov/geomag/data.shtml&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&#xA;  Following the link &quot;Magnetic Model maps and grids&quot; I took &lt;a href=&quot;ftp://ftp.ngdc.noaa.gov/geomag/Grid/D_map_mf_2010.zip&quot; rel=&quot;noreferrer&quot;&gt;D_map_mf_2010.zip&lt;/a&gt; which contains a simple lat/lon/declination table (0.5° steps) and wrote a small simulation which moves the aircraft 10 km along the heading, calculates &amp;amp; records the new angular coordinates, moves again and so on. The result is this figure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yqH8l.png&quot; alt=&quot;World declination chart, with course&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/BsD1y.png&quot; alt=&quot;Zoomed in on course &amp;amp; original intended destination&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The green arrows show the direction of north as displayed by a compass, the blue shows the direction of east.&lt;br&gt;&#xA;The black line was generated by the simulation shows the true course of an aircraft with a constant magnetic heading of 90°. While it will fly over north Florida, it deviates markedly to the north over the ocean and just touches the north coast of Spain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this only accounts for the magnetic declination, since your question assumed no wind.&lt;br&gt;&#xA;During a real flight the aircraft may experience unknown crosswinds, so the actual position has to be determined from time to time, and a look into the table / map shows the correct heading at the current position leading to your destination. (If the aircraft only has this map, a compass and a sextant aboard.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, if you have this data, you can correct the compass headings such that you fly the true course you want. However, I don't know how it's actually done in aviation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://drive.google.com/file/d/0B35PEoocpueJVnJXUklIbkhuR1k/view&quot; rel=&quot;noreferrer&quot;&gt;Here is the code&lt;/a&gt;. It is written in python and gnuplot, and you will not need any programming skills to use it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have fun!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer one question from the comments:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you carried on around the world, would you return to your starting point? I'm guessing yes as we would be following a contour of equal magnetic potential?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the physics side, magnetic fields are not conservative and so do not have a potential. However, I think it's clear what you mean. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as the heading is +90° or -90°, you will end up where you started. The following figure again shows a travel from KLAX heading 90°, but with a total lengh of 40mio km (i.e. 1000 times the circumfence of the earth and a little more turns for the track as it's not at the equator)&#xA;As you can see, there is just a single black track, no deviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you want to fly to Casablanca, you will need a constant heading of 93,6°. And if you don't land there and have enough fuel, strange things happen:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rj3K4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also like to emphasize Bob Jarvis' comment, about how it's done in the real world:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Long distance journeys, whether by air or sea, will generally use a &quot;great circle&quot; where the heading steered is not constant. In practice the continuously changing great circle course is broken up in to a series of segments of constant heading. Reference &lt;a href=&quot;http://en.wikipedia.org/wiki/Great_circle&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-11-08T09:00:12.793" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="13250" PostTypeId="2" ParentId="13242" CreationDate="2015-03-14T14:46:06.163" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airlines_for_America&quot; rel=&quot;nofollow&quot;&gt;Airlines for America&lt;/a&gt; &lt;em&gt;(formerly known as Air Transport Association of America (ATA))&lt;/em&gt; &lt;a href=&quot;https://publications.airlines.org/&quot; rel=&quot;nofollow&quot;&gt;maintains a website&lt;/a&gt; for their publications and subscriptions. You can access all/several of their specification documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spec 100 (Manufacturers' Technical Data) can be downloaded from &lt;a href=&quot;https://publications.airlines.org/CommerceProductDetail.aspx?Product=33&quot; rel=&quot;nofollow&quot;&gt;this page&lt;/a&gt;, by just paying &lt;strike&gt;an exorbitant&lt;/strike&gt; a minimal fee of $650.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure which spec contains Chapter 206.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-14T14:46:06.163" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13253" PostTypeId="1" AcceptedAnswerId="13254" CreationDate="2015-03-15T11:06:13.963" Score="36" ViewCount="3513" Body="&lt;p&gt;My 8 year old recently got a guided tour of the parachute-packing station at the local sport airport. Afterwards she asked me what happens if the parachute is improperly packed. Since it seemed to me that each parachute is packed by one person, there is no checking of human error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How resilient are modern sport parachutes to packing errors?&lt;/strong&gt; I would include in that any improper packing method or the packer overlooking some detail such as wear or tears. I'm not a parachutist so I don't know the intricacies to ask a more nuanced question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Proud father update:&lt;/strong&gt; A bit belated, but she's no longer eight years old and she enjoys, in her words, &lt;a href=&quot;https://www.youtube.com/watch?v=AQeyg5QBcDQ&quot; rel=&quot;noreferrer&quot;&gt;floating on imagination&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="354" LastEditDate="2017-01-19T08:17:17.000" LastActivityDate="2019-07-31T13:30:20.727" Title="How robust are modern parachutes to folding errors, wear, or other problems?" Tags="&lt;parachute&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13254" PostTypeId="2" ParentId="13253" CreationDate="2015-03-15T13:11:53.887" Score="41" Body="&lt;p&gt;Qualification: I am a master parachute rigger, taught the sport for 10 years and have packed a couple of thousand emergency parachutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can put an apartment-size piece of nylon into a purse in under 5 minutes, and guarantee that it will open. How nicely it opens is a different question. It usually takes about 45 minutes to service an emergency parachute - 20 minutes to inspect it, 10  to fold it up nicely, another 10 to stuff it into the pack, then the paperwork. Double that time if it's a large 2-passenger parachute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;fold it up nicely&quot; part is to make it go into the pack without any unsightly bulges, and the emergency packs are never a nice open bag like the main - the canopy has to be shaped around the closing apparatus and the spring-loaded extraction chute has to fit in the middle. Very little of this process has anything to do with ensuring it opens when needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A packer would have to be spectacularly incompetent to fold a canopy in a way that would cause it to malfunction. If you feel the fabric used to make main parachutes you will find that it is extremely slippery - good luck keeping that stuff in the proper place when it goes into the bag, but you don't need to. These things sort themselves out quite nicely most of the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two important tools used in packing emergency packs - one is appropriately called the Death Strap. It is wrapped around the middle of the canopy as you are folding it into the bag, and if you forget to remove it the canopy will not open. The other is a locking pin used to close each part of the pack in stages. Your mistake will probably make the front page of the local newspaper and involve a lot of time with your lawyer, so packers typically only own one of each and all tools are counted after each job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going back to the incompetent packer for a moment - the main parachute is usually packed by the owner, and very occasionally you need to open and re-close the pack. If you are lazy or rushed it is very easy to close the main pack in a way that prevents it from opening. Owners (almost) never open their emergency packs, and riggers follow a standard process to prevent these errors from happening.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2015-03-15T13:21:43.930" LastActivityDate="2015-03-15T13:21:43.930" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13255" PostTypeId="1" AcceptedAnswerId="13256" CreationDate="2015-03-15T13:36:26.070" Score="1" ViewCount="928" Body="&lt;p&gt;I noticed on this video of &lt;a href=&quot;https://www.youtube.com/watch?v=21vkambAtFk&quot; rel=&quot;nofollow&quot;&gt;an A380 landing in rain&lt;/a&gt; that reverse thrust was applied to only the inboard engines. &lt;strong&gt;Do the outboard engines not have reverse thrusters?&lt;/strong&gt; If they don't, then why not? If they do, then why not use them on a slippery landing?&lt;/p&gt;&#xA;" OwnerUserId="354" LastActivityDate="2015-03-15T13:59:35.933" Title="A380 reverse thrust on only half the engines" Tags="&lt;airbus&gt;&lt;airbus-a380&gt;&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2015-03-15T16:08:21.047" ContentLicense="CC BY-SA 3.0" />
  <row Id="13256" PostTypeId="2" ParentId="13255" CreationDate="2015-03-15T13:51:44.993" Score="5" Body="&lt;p&gt;Yes, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Engines&quot; rel=&quot;nofollow noreferrer&quot;&gt;outboard engines&lt;/a&gt; do not have reverse thrust to avoid them kicking up dirt. On a regular runway they will be outside of the concrete surface, so using reverse thrust there will incur the risk of foreign object damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was already covered in &lt;a href=&quot;https://aviation.stackexchange.com/questions/6361/why-doesnt-the-a380-use-its-outboard-thrust-reversers?rq=1&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-15T13:59:35.933" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13257" PostTypeId="1" AcceptedAnswerId="13258" CreationDate="2015-03-15T14:16:48.750" Score="17" ViewCount="4802" Body="&lt;p&gt;In this question &lt;a href=&quot;https://aviation.stackexchange.com/questions/13255/a380-reverse-thrust-on-only-half-the-engines&quot;&gt;A380 reverse thrust on only half the engines&lt;/a&gt; some doubts were raised about the strength of structures in certain directions.&#xA;Specifically, Peter Kämpf states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aluminium and Carbonfiber are almost as good in compression as in&#xA;  tension, so the direction of the load is secondary. This is not true&#xA;  if buckling stiffness is not sufficient, but in case of wing in-plane&#xA;  bending, buckling is of no concern. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This made me wonder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How come V-n diagrams are not symmetric?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xcZBu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the image it can be seen that the structure at 150 knts can only cope with -1.8g, but +3.8g.&#xA;Where does this difference come from, is it coming from difference in buckling stifnesses in different directions? &lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="14897" LastEditDate="2021-04-17T18:37:44.910" LastActivityDate="2021-04-17T18:37:44.910" Title="How come planes can endure more positive than negative g's? I.e. how come V-n diagrams are not symmetric?" Tags="&lt;aircraft-design&gt;&lt;aircraft-structures&gt;&lt;aircraft-limitations&gt;&lt;flight-envelope&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13258" PostTypeId="2" ParentId="13257" CreationDate="2015-03-15T14:44:31.917" Score="17" Body="&lt;p&gt;The lines start at zero load factor because with no speed there is no lift. If you move further right, the upper line is determined by the maximum lift, while the lower line is determined by the minimum lift. Both have the same value only for symmetric airfoils - regular airfoils are optimized for creating lift in only one direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The upper and lower maximum load factor limits of the v-n-diagram are mostly determined by maximum gust loads in level flight, and in this condition they are represented by lines emanating from +1 g, such that the distance from +1 g in terms of positive and negative load factors should be the same. Add to this that your wings will create approximately 50% more force until they reach their maximum lift as compared to the minimum ( = maximum negative) lift (the details depend on the airfoil, of course), and then your load factor limits will be 1 + 1.5$\cdot$gust load factor in positive and 1 - gust load factor in negative direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an example I have uploaded the polar of a supercritical airfoil which I calculated years ago with Mark Drela's ISES. It's the best I could find quickly - most polars only show the positive maximum lift, not the limit at the opposite end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UAOmg.png&quot; alt=&quot;Polar plot of the R2A airfoil at Mach 0.6&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the maximum $c_L$ is +1.3, while the minimum $c_L$ is only -0.8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at a practical case: Utility category airplanes must be certified for +3.8 gs and -1 g. In level flight a positive vertical gust (updraft) might add +2.8 g. The same gust strength in negative direction (downdraft) will cause a load change of only -1.9 g (because the wing will stall earlier), which, when added to the regular 1 g at level flight will translate into a -0.9 g load factor. Close enough for limiting the negative load factor at -1 g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher speed the gust will not stall the airfoil in either direction, and now we can simply assume that a gust will produce a positive load of 1 + gust load factor and a negative load of 1 - gust load factor. Let the gust load factor be 2.8, and your limits will be +3.8g and -1.8g, like in your example at 150 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far, I have looked at the rationale behind the load limits for certification. But also in real life there is a difference between positive and negative load factors: The wing spar has to carry the bending moment due to lift minus the wing weight. If it would need to carry the same aerodynamic loads in both directions (up and down), the wing weight would reduce the total positive load, but would make the total negative load greater. This is why the structure cannot endure the same load factors in both directions: You need to give the wing some margin to carry its own weight in addition to the aerodynamic loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things look differently if you take the v-n-diagram of aerobatic category airplanes. Now you cannot readily assume that the plane will only fly straight, but you need to assume that it will be hit by a gust while flying upside down. Add to this that the symmetric airfoil will create the same lift in both directions before it stalls, and your envelope needs to be limited at ±6 g, making the envelope symmetric.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T09:11:11.787" LastActivityDate="2015-05-10T09:11:11.787" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13259" PostTypeId="1" AcceptedAnswerId="13260" CreationDate="2015-03-15T16:30:37.450" Score="11" ViewCount="2653" Body="&lt;p&gt;I see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2001/why-are-you-required-to-commit-to-a-full-stop-landing-if-reverse-thrust-is-selec?rq=1&quot;&gt;many questions regarding&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow noreferrer&quot;&gt;the unreliability of&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/6361/why-doesnt-the-a380-use-its-outboard-thrust-reversers&quot;&gt;thrust reversers&lt;/a&gt;. &lt;strong&gt;Why are these components so faulty across all airplane models and manufacturers?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a technical challenge to making the the thrust reversers as reliable as other aviation systems? Are the A380's electronic thrust reversers more reliable than the traditional mechanical or hydraulic reversers?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-16T13:38:11.583" Title="Why are thrust reversers so unreliable?" Tags="&lt;thrust-reverser&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13260" PostTypeId="2" ParentId="13259" CreationDate="2015-03-15T17:33:11.960" Score="27" Body="&lt;p&gt;It's not so much that thrust reversers (TRs) are more unreliable than other components of the plane. However, they have a very important impact on the airplane's performance. Hydraulics, flaps, and even engines fail &lt;strong&gt;regularly.&lt;/strong&gt; But &lt;a href=&quot;https://aviation.stackexchange.com/q/12257/1696&quot;&gt;engines&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/1583/1696&quot;&gt;hydraulics&lt;/a&gt; can be backed up by redundant systems, and an airplane can still &lt;a href=&quot;https://aviation.stackexchange.com/q/5049/1696&quot;&gt;land without flaps&lt;/a&gt;. But engineers learned from &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lauda Air Flight 004&lt;/a&gt; that an airplane may not be controllable if the TRs deploy in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in the interest of safety, the TRs have additional precautions. The reasons for not aborting a landing after they are deployed are discussed in your first linked question. Reliability is also not the only reason for having no TRs on the A380 outboard engines, as discussed in the second linked question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question, there is indeed a technical challenge in making the TRs reliable: &lt;em&gt;they absolutely must not deploy in flight&lt;/em&gt;. This means many safeguards are put in place, and they are &lt;strong&gt;designed to fail&lt;/strong&gt; by not deploying if there is any doubt about whether it is safe. A TR that won't deploy is more desirable than a TR that deploys when you don't want it to.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-16T12:13:36.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13262" PostTypeId="2" ParentId="13257" CreationDate="2015-03-16T00:38:14.110" Score="9" Body="&lt;p&gt;To put it simply, it is because the aircraft is &lt;em&gt;designed&lt;/em&gt; to be stronger in the +G direction. It is not required to be as strong in the -G direction (since it will not experience high negative G loads during operations), so it is not designed that way. To do so would cause much unnecessary structural weight.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastActivityDate="2015-03-16T00:38:14.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13263" PostTypeId="2" ParentId="2814" CreationDate="2015-03-16T01:55:47.970" Score="5" Body="&lt;p&gt;A few years ago, I had a similar need for airport data from European countries, amongst which was Greece.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After going through a number of alternative resources, I settled for the data files of the flight simulator X-Plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-Plane uses sime simple data files to define the position and characteristics of airports. See for example: &lt;a href=&quot;http://data.x-plane.com/get_data.html&quot; rel=&quot;noreferrer&quot;&gt;http://data.x-plane.com/get_data.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of these datasets included the location, type of runway, airspace, runway orientation and comms freqs, practically for airports across the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data is collected from various sources and kept up to date by the community. As far as Greece was concerned, all main airports of interest were described accurately enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the desired accuracy and purpose, you might find this database useful too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;" OwnerUserId="4181" LastActivityDate="2015-03-16T01:55:47.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13264" PostTypeId="1" AcceptedAnswerId="13266" CreationDate="2015-03-16T02:46:26.930" Score="14" ViewCount="108467" Body="&lt;p&gt;&lt;a href=&quot;https://www.reddit.com/r/pics/comments/2z69q8/had_a_flight_from_phoenix_to_chicago_last_night/&quot; rel=&quot;noreferrer&quot;&gt;These guys say (in the discussion)&lt;/a&gt; that they were the only three passengers on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does that mean that there was no Air Marshal on board (or one of them was?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aren't air marshals present on every flight?&lt;/p&gt;&#xA;" OwnerUserId="7645" LastEditorUserId="3775" LastEditDate="2015-03-16T22:25:32.083" LastActivityDate="2015-09-15T10:34:43.997" Title="Are air marshals on every flight?" Tags="&lt;airline-operations&gt;&lt;security&gt;&lt;fams&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13265" PostTypeId="2" ParentId="13264" CreationDate="2015-03-16T03:21:06.803" Score="9" Body="&lt;p&gt;Air marshals are certainly not on every flight. With 80,000 flights daily in North America it would be nearly impossible, and most flights are low-risk. Billings, MT to Denver, CO in a Dash-8 simply isn't worth the effort to either police it or hijack it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Higher ratios of marshals to flights will be found going into the major centers, and it likely approaches 1:1 going into the DC area.&lt;/p&gt;&#xA;&#xA;&#xA;" OwnerUserId="1632" LastEditorUserId="-1" LastEditDate="2015-03-16T12:32:42.117" LastActivityDate="2015-03-16T12:32:42.117" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13266" PostTypeId="2" ParentId="13264" CreationDate="2015-03-16T03:46:48.657" Score="26" Body="&lt;p&gt;The exact number of air marshals is not public information, and they certainly don't disclose what flights they fly on or other operational details. However, the number &lt;a href=&quot;http://www.cnn.com/2014/02/25/us/air-marshals-cut/&quot; rel=&quot;noreferrer&quot;&gt;has been reported&lt;/a&gt; to be on the order of ~3,000-4,000 and reports indicate the number has decreased somewhat since then. All of them are, of course, not on duty 24/7/365. There are around &lt;a href=&quot;http://webcache.googleusercontent.com/search?q=cache:CSoyXSzfPawJ:sos.noaa.gov/Datasets/dataset.php%3Fid%3D44%20&amp;amp;cd=1&amp;amp;hl=en&amp;amp;ct=clnk&amp;amp;gl=us&quot; rel=&quot;noreferrer&quot;&gt;87,000 flights&lt;/a&gt; a day in the US alone, but only around 28,000 are commercial passenger flights, where air marshals are presumably most likely (hopefully there's not a need for air marshals on military flights, for instance).&lt;/p&gt;&#xA;&lt;p&gt;So for some back of the envelope math, let's conservatively say there are 3,500 air marshals who all work five days a week, they all work alone (in reality, they appear to work at least in pairs), and they somehow manage to average protecting four flights a day. Even with these conservative assumptions, that would only be 5000 flights/day covered by air marshals. From this, it should be clear that there cannot possibly be an air marshal on every commercial flight in the US.&lt;/p&gt;&#xA;&lt;p&gt;The President of the Air Marshal Association/CWA (their union), not entirely a disinterested party, &lt;a href=&quot;http://www.usatoday.com/story/travel/flights/2014/08/07/5-myths-about-air-marshals/13724331/&quot; rel=&quot;noreferrer&quot;&gt;agrees&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;quot;There are around 30,000 commercial flights per day over the U.S.,&amp;quot; says Casaretti. &amp;quot;If you were to attempt to place a team of just two FAMs on each flight, it would require an agency of over 75,000 FAMs (accounting for training and days off). FAMs cover a very small percentage of commercial flights.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Which flight air marshals get on is determined by a computer program that assesses the probability of threat based on the aircraft, departure and destination cities, as well as the amount of fuel on board. This is the threat matrix that comes out of the missions operation center.&lt;/p&gt;&#xA;&lt;p&gt;The TSA will not release statistics on the number of air marshals. TSA's Pascarella acknowledges only &amp;quot;many thousands.&amp;quot; But Biles estimates that there are approximately 3,300 FAMs and of those, 34% are filling ground assignments in training, operations and management.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;We call them 'chair marshals,' riding out their career in management,&amp;quot; says Biles. That leaves 66% of the workforce to perform in-flight security duties.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;If one accounts for vacations, sick leave, medical leave and days off, some air marshals working in operations have told me that this accounts for less than one half percent of all U.S.-flagged aircraft being covered by federal air marshals,&amp;quot; he says.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="5568" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-16T03:46:48.657" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13267" PostTypeId="2" ParentId="13202" CreationDate="2015-03-16T07:27:55.183" Score="2" Body="&lt;p&gt;The theory is actually quite simple and straightforward. It should go like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In one-engine flight, the asymmetric prop position will pull the aircraft into a sideslip. The sideslip-induced rolling moment will then proceed to roll the aircraft such that the airplane rolls over the dead engine - something every multi-engine pilot learns to avoid early, because it will be hard to get the airplane back to level flight in this configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the single operating propeller will give the center wing an increased angle of attack due to the propeller swirl, and the outer wing a lower angle of attack, the prop produces a rolling moment which works against the sideslip-induced rolling moment, and should make it easier to avoid rolling over the dead engine. Engine torque will work against this moment, but the induced rolling moment of the wing is stronger, leaving a net moment which rolls the aircraft over the operating engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This should apply to all multi-engined aircraft. My reasoning why it didn't work for the F-82 can be read &lt;a href=&quot;https://aviation.stackexchange.com/questions/12979/why-did-upward-turning-propellers-in-the-f-82-twin-mustang-cause-a-loss-of-lift/13268#13268&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-16T21:10:29.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13269" PostTypeId="1" AcceptedAnswerId="13271" CreationDate="2015-03-16T08:24:46.497" Score="40" ViewCount="41341" Body="&lt;p&gt;Is this rule even true and why is it? I'm going to assume it has to do with pressure but can someone give me a good explanation?&lt;/p&gt;&#xA;" OwnerUserId="7624" LastEditorUserId="14897" LastEditDate="2017-05-09T19:00:51.613" LastActivityDate="2018-04-11T16:23:22.510" Title="Why must one wait 48 hours to fly, after scuba diving?" Tags="&lt;safety&gt;&lt;medical&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13270" PostTypeId="1" AcceptedAnswerId="13272" CreationDate="2015-03-16T08:25:42.817" Score="29" ViewCount="6748" Body="&lt;p&gt;What are the top causes of a parachute failing to work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &quot;parachute&quot;, I mean primarily sporting parachutes, such as used in skydiving, but information about military (paratroop) chutes, ejector seat chutes, etc., would be useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &quot;failing to work&quot;, I mean &quot;fails to prevent the sudden stop at the bottom&quot;, whether this is through failing to deploy properly, getting tangled, structural failure or whatever.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Inspired by the following comment on this &lt;a href=&quot;https://aviation.stackexchange.com/a/13254/2719&quot;&gt;answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;maybe you could add something about why sometimes chutes don't open. –  rbp&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2719" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2018-08-23T19:40:26.290" Title="What are the major causes of parachutes failing to work?" Tags="&lt;parachute&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13271" PostTypeId="2" ParentId="13269" CreationDate="2015-03-16T08:52:46.590" Score="51" Body="&lt;p&gt;Yes It's true. And yes it's related to pressure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you heard of &quot;The bends&quot; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Decompression_sickness&quot; rel=&quot;nofollow noreferrer&quot;&gt;decompression sickness&lt;/a&gt;? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As divers go deeper the pressure increases. The longer you dive and deeper you go the more nitrogen is absorbed into your blood as a dissolved gas. As you return to the surface the pressure reduces and the nitrogen reverts to a gas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This decompression needs to be done slowly so the nitrogen can pass back out through your lungs.  If you ascend too fast the nitrogen can form bubbles in your blood (Just like when you open a bottle of coke.) which can be painful and possibly fatal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even once you have finished diving you will still have residual nitrogen in your blood which will take time to release.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air pressure reduces further when you fly. If you finished a dive and got in a plane the rapid climb in altitude would result in a drop in pressure similar to a rapid ascent while diving. So you would run the risk of getting the bends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small planes aren't pressurized. But even pressurized planes might not maintain atmospheric pressure when flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This topic should have been covered if you have taken a dive course. &lt;/p&gt;&#xA;" OwnerUserId="7647" LastEditorUserId="7647" LastEditDate="2018-04-11T07:15:55.700" LastActivityDate="2018-04-11T07:15:55.700" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="13272" PostTypeId="2" ParentId="13270" CreationDate="2015-03-16T09:21:13.350" Score="33" Body="&lt;p&gt;&amp;#72;ello - your Friendly Neighborhood Parachute Rigger here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sport chutes are pretty reliable, have been since the mid 90s to the point where more accidents happen under fully functional canopies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we disregard rank stupidity like tying the flaps shut&lt;sup&gt;1&lt;/sup&gt; or incompetent packing we find that the leading cause of malfunctions is bad body position on deployment. You are supposed to be face down, shoulders level before opening the thing. If you are on your back or tumbling you can have various parts wrap around you. High-performance canopies are somewhat more sensitive to the shoulders being level and can open in a decently fast spin. Depending on the spin direction and your altitude you may not be able to recover&lt;sup&gt;2&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The emergency chutes are built differently, emphasizing (obviously) reliability over being able to land at 100km/h. This means that twisted lines are either recoverable or not an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the jumper isn't paying attention to where he is, you may find that a leading cause of going splat is not using the perfectly good canopy on your back. Automatic activators have more-or-less eliminated this as a common cause&lt;sup&gt;3&lt;/sup&gt;, but if the jumper thinks that the houses look a bit too big and deploys the main at the same time as the reserve opens they may decide to wrap each other up. Ram-air canopies are like badgers - they don't like each other very much and having two open at the same time is a rather delicate situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we turn to landing accidents, we find that there are all kinds of ways to injure or kill yourself with a fully functional canopy overhead. The aforementioned 100km/h landing speed is no joke - hit an obstacle on the ground going that fast and it's exactly the same as jumping out of a car on the highway. Buildings, trees, power lines, vehicles, running propellers etc. have all claimed their sacrifices. And don't try to land on both sides of the fence at the same time. Or in the alligator farm across the road.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mechanical failure of the system is very rare - riggers won't pack worn-out reserves, and if they are concerned about someone's main they will tell the dropzone management who will usually decline to provide services until it's fixed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Many jumpers will tie various handles to the pack before travelling. Prevents the pack accidentally opening when curious security or customs pick it up by what looks like the carry handle. Remove before Flight!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Happened to me twice - the first time I looked up, then down, decided I didn't have enough time to fix it. The second time it was spinning the other way and I fixed it in 2 seconds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Automatic activators fire at 750-1000 feet. If you are in freefall below that altitude you're usually done.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2015-03-16T23:38:44.763" LastActivityDate="2015-03-16T23:38:44.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13273" PostTypeId="2" ParentId="13269" CreationDate="2015-03-16T09:48:52.013" Score="10" Body="&lt;p&gt;To add a reference to Peter's answer, &lt;a href=&quot;http://www.padi.com/rdp/erdp/General_Rules_using_the_eRDP.htm&quot; rel=&quot;noreferrer&quot;&gt;from PADI&lt;/a&gt;, one of the institutions that releases Scuba diving certificates:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Flying after Diving Recommendations&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;For Dives within the No-Decompression Limits&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Single Dives: A minimum preflight surface interval of 12 hours is suggested.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Repetitive Dives and/or Multi-Day Dives: A minimum preflight surface interval of 18 hours is suggested.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;For Dives requiring decompression stops&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;A minimum preflight surface interval of greater than 18 hours is suggested.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-16T09:48:52.013" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13275" PostTypeId="2" ParentId="13264" CreationDate="2015-03-16T10:29:33.207" Score="15" Body="&lt;p&gt;Air marshalls are not on every flight. I was recently at a computer science seminar by Milind Tambe, whose research team developed the software that the Federal Air Marshal Service uses to randomly choose which flights get marshals. (It's also used for security patrols at LAX, coastguard patrols at various ports and even for anti-poaching patrols in Uganda's national parks.) Note that &quot;randomly&quot; doesn't mean uniformly at random: certain flights are more likely to be covered than others, depending on the perceived level of threat.  But the fact that they choose which flights get marshals clearly means that some flights don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who are interested, &lt;a href=&quot;http://teamcore.usc.edu/projects/security/&quot;&gt;Prof. Tambe's website&lt;/a&gt; has a lot of information, including some explanatory videos.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-03-16T10:29:33.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13276" PostTypeId="2" ParentId="13259" CreationDate="2015-03-16T13:38:11.583" Score="2" Body="&lt;p&gt;I would disagree with the assertion or assumption in the question that TR's as &quot;so faulty&quot; and significantly less reliable than other systems.  Based on my experience, the reliability of TR's is probably between 99% and 99.9% -- in other words the times when a TR fails to work is between 1 in 100 and 1 in 1000 flights.  That, to me, doesn't look like a particularly bad record.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern aircraft in general are extremely reliable, so when you compare a component with a 99.x% record against a component with a 99.999% record (say, a windshield -- how often do you see those fail?), the former doesn't look good in the comparison.  But when you consider that there are thousands of commercial flights daily in the US, and it's uncommon for anything significant to make the news, the reliability rate for the system as a whole is extremely good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of this is fault tolerance; on most runways, unexpected loss of a TR doesn't affect things very much.  The vast majority of the time, braking performance is entirely adequate to stop the aircraft well before the end of the runway even with no reverse thrust (not merely one of two or one of four failed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in over a decade of flying modern jet aircraft, the number of times I've seen a TR fail to deploy I could probably count on the fingers of one hand, so all in all I'd suggest that they tend to be quite reliable.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-16T13:38:11.583" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13277" PostTypeId="2" ParentId="13269" CreationDate="2015-03-16T15:12:40.043" Score="9" Body="&lt;p&gt;It's not just blood, but soft tissue generally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;48 hours is extremely conservative - recreational (single tank of air, 40metre maximum depth) diving guidelines say only 24 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't forget altitude (lakes at &gt; 300metres) diving also affects &lt;a href=&quot;http://scuba.about.com/od/DiveTheory/p/What-Is-A-No-Decompression-Limit.htm&quot;&gt;No-Decompression Limits&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7652" LastEditorUserId="65" LastEditDate="2015-03-16T15:21:26.360" LastActivityDate="2015-03-16T15:21:26.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13278" PostTypeId="1" AcceptedAnswerId="13286" CreationDate="2015-03-16T15:30:55.570" Score="7" ViewCount="14831" Body="&lt;p&gt;I was looking at a couple of helicopters on Wikipedia (specifically the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_A160_Hummingbird&quot; rel=&quot;noreferrer&quot;&gt;Boeing A160&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Robinson_R22&quot; rel=&quot;noreferrer&quot;&gt;Robinson R22&lt;/a&gt;, and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_S-64_Skycrane&quot; rel=&quot;noreferrer&quot;&gt;Sikorsky S-46&lt;/a&gt;) and I noticed the main rotor diameters seem to be pretty similar to the helicopter length &lt;em&gt;(see below)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason for this, or is it just coincidence? I thought it might be that helicopters are just long enough for the tail rotor to not interfere with the main rotor, but that doesn't seem to work out, because the rotors aren't quite centered over the helicopter.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Helicopters' length and main rotor diameter legend:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                Length     Rotor Diameter&#xA;Boeing A160      35'0&quot;        36'0&quot;&#xA;Robinson R22     28'8&quot;        25'2&quot;&#xA;Sikorsky S-64    70'3&quot;        72'0&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="65" LastEditDate="2015-03-16T15:42:19.053" LastActivityDate="2020-07-25T21:26:32.560" Title="What is the relation between a helicopter's length and rotor diameter?" Tags="&lt;helicopter&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13279" PostTypeId="2" ParentId="2001" CreationDate="2015-03-16T15:38:25.403" Score="14" Body="&lt;p&gt;Once they're out, you're committed to stop because you don't know if, and how quickly/symmetrically, they'll stow.  Even with a long, long runway, if you push up the power and one reverser is still out, you're going off the side -- one side of the aircraft is producing forward thrust, the other is producing reverse thrust, you're done!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the safety interlocks &amp;amp; features in the TR's are all about preventing uncommanded deployment -- since that might well be unsurvivable in flight.  But when you HAVE commanded the deployment, those safety features are all satisfied.  There isn't any similar level of engineering to guarantee that they stow, and do so simultaneously, because you're simply TOLD, don't try to take off once the TR's are out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one fails to stow at the end of the landing roll, the effect is pretty minimal with the power at idle and the aircraft at or near taxi speed, so in general there aren't great issues with the TR's perhaps still out after you're done with them.  The one case where it's a grave issue is handled with a policy solution (&quot;don't&quot;) rather than an engineering solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as realizing that you touched down too long and you need to take it back airborne rather than trying to stop, that IS possible... right up until the point that you deploy the TR's.  Then you're committed.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-16T15:38:25.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13280" PostTypeId="1" AcceptedAnswerId="13281" CreationDate="2015-03-16T15:53:36.070" Score="11" ViewCount="4387" Body="&lt;p&gt;In this particular map&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NoKEP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;from &lt;a href=&quot;http://skyvector.com&quot; rel=&quot;noreferrer&quot;&gt;SkyVector&lt;/a&gt;, what are the meanings of the different colored circles, and for the different amounts of 'fill-in'?  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's obvious by hovering over them, that they are weather stations, as the weather info will pop-up, but there doesn't seem to be anything (to my untrained eye) about the weather pop up that would indicate a need for the different colors.&lt;/li&gt;&#xA;&lt;li&gt;It's also obvious that the color doesn't indicate something permanent about the station, as last Friday, there were large swathes of different colors across the USA, while today almost everything is green.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-03-17T19:42:24.093" Title="What do the different colors of weather stations indicate on SkyVector?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13281" PostTypeId="2" ParentId="13280" CreationDate="2015-03-16T16:10:38.487" Score="10" Body="&lt;h1&gt;Colors&lt;/h1&gt;&#xA;&lt;p&gt;At present&lt;sup&gt;1&lt;/sup&gt;, &lt;a href=&quot;http://aviationweather.gov/taf/help?page=inter&quot; rel=&quot;noreferrer&quot;&gt;they mean &lt;em&gt;(image source)&lt;/em&gt;&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ByQNz.png&quot; alt=&quot;Color codes&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;For more details, please &lt;a href=&quot;http://aviationweather.gov/adds/metars/description/page_no/4&quot; rel=&quot;noreferrer&quot;&gt;see this description&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h1&gt;Fill-ins&lt;/h1&gt;&#xA;&lt;p&gt;These are called sky/cloud coverage.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aQK1M.gif&quot; alt=&quot;Sky/Cloud Covers&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.hpc.ncep.noaa.gov/html/stationplot.shtml&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;a href=&quot;https://skyvector.com/comment/2820#comment-2820&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;From SkyVector:&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The color is controversial because the FAA is making the NWS swap the&#xA;colors for VFR and MVFR. When the new aviationweather.gov becomes the&#xA;current aviationweather.gov, we'll change our colors to match.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-17T19:42:24.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13282" PostTypeId="1" CreationDate="2015-03-16T16:37:25.603" Score="0" ViewCount="1413" Body="&lt;p&gt;I suppose they do both, but what percentage of the kinetic energy is absorbed by the wheel brakes and what percentage by air-friction (in typical cases)?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-03-16T16:53:25.517" Title="Do landing planes brake with wheel-brakes or air-brakes or both?" Tags="&lt;braking&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-03-16T17:16:36.543" ContentLicense="CC BY-SA 3.0" />
  <row Id="13283" PostTypeId="2" ParentId="13282" CreationDate="2015-03-16T16:53:25.517" Score="1" Body="&lt;p&gt;Depends on how long the runway is.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a 12,000' runway and your terminal is at the far end of it, you can roll out with no wheel braking and as little (or no) reverse thrust as you're allowed, and you'll be close to taxi speed by the time you're ready to turn off.  In that case, the brakes only absorb enough energy to get you from maybe 60-80 knots down to 20-30, since the drag devices lose most of their effectiveness by that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, on a really short runway, you may be getting on the brakes immediately after touchdown, which means that the amount of time that you're dissipating energy due to drag (spoilers) and reverse thrust is reduced, and much less energy is lost that way.  So in that case the brakes get a great deal of your kinetic energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The case beyond that would be if you didn't use reverse thrust, your brakes would get nearly all of your energy, with only a small amount dissipated due to aerodynamic drag.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-16T16:53:25.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13285" PostTypeId="1" CreationDate="2015-03-16T19:55:42.537" Score="5" ViewCount="287" Body="&lt;p&gt;I have a 2001 Cessna 182T with King avionics. The KMD-550 moving map display correctly shows &quot;track up&quot; but the little airplane icon is always pointed to the north. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I set this so that it points track up as well, or is there some kind of fault with the unit?&lt;/p&gt;&#xA;" OwnerUserId="7657" LastEditorUserId="19" LastEditDate="2015-03-16T19:59:07.260" LastActivityDate="2018-02-24T17:56:11.073" Title="Is the Bendix/King KMD-550 airplane icon always oriented to the north?" Tags="&lt;avionics&gt;&lt;gnss&gt;&lt;cessna-182&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13286" PostTypeId="2" ParentId="13278" CreationDate="2015-03-16T20:13:32.877" Score="6" Body="&lt;p&gt;&lt;strong&gt;Important&lt;/strong&gt;.  I am a helicopter pilot, with no expertise or experience in design so I can give you &lt;strong&gt;reasons&lt;/strong&gt; for this, but not design detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most design decisions are compromises.  Helicopter rotors are definitely compromises.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What is the aim of the rotor design?&lt;/em&gt;&lt;/strong&gt;&#xA;To have the smallest possible rotor to achieve the performance requirements of the craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What limits the smallest size?&lt;/em&gt;&lt;/strong&gt;&#xA;Let's assume that the blades are as efficient at generating lift as you can make them.  There are only 2 ways to increase lift for any given blade at any given angle of attack.  That is to increase the length of the blade or to move it faster through the air, i.e. to make the rotor spin faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What limits the speed at which the rotor can rotate?&lt;/em&gt;&lt;/strong&gt;&#xA;As the blade tip speed gets faster, drag increases with the square of the speed.  Increased drag means increased power required which means heavier engine and heavier gearbox.  As speed moves to a high percentage of supersonic, turbulence and therefore drag increases enormously.  The longer the blade, the lower the possible rotor RPM since the tip approaches supersonic speed more quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why not just increase the length?&lt;/em&gt;&lt;/strong&gt;&#xA;Because the blade becomes increasingly difficult (and expensive) to manufacture to handle the loads on the blade and the heavier they become requiring more robust and heavier rotors hub assemblies.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inner part of the rotor also produces little lift since it is moving relatively slowly and since lift decreases with the square of the speed, the lift generated falls away rapidly as you move to the inside portion of the disc.  As you increase the length of the blade, without being able to increase the speed of the disc as above, the area of the disc which is &quot;useless&quot;, increases as a proportion of the overall disc size.  Therefore, more power is needed to rotate the increasingly large useless area of the disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;The lower the disc loading, the more efficient the helicopter is in the hover&lt;/em&gt;&lt;/strong&gt;.&#xA;The disc loading is the ratio of the weight of the helicopter and the area the rotor disc describes as it rotates.  The disc loading should be as low as possible to reduce the required strength, and thus weight, of the blades especially as the weight of the helicopter increases under positive G which in turn increases the disc loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Non-performance considerations.&lt;/em&gt;&lt;/strong&gt;  Parking; hangar space required; ability to operate in confined areas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given these (and other design parameters), the rotor sizes you quote will have been arrived at by factoring each of the variables to find the best compromise, according to the designer, between them to achieve the desired performance goals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, I don't believe that there is a relationship between the fuselage length and rotor size, possibly with some influence from the need to park and hangar the resulting craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&#xA;I've been hoping that some better informed answers would be added.  As there are none, I'll continue with my simple pilot guesswork.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What is the aim of the fuselage design?&lt;/em&gt;&lt;/strong&gt;&#xA;To have the smallest possible fuselage to achieve the performance requirements of the craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What limits the smallest size?&lt;/em&gt;&lt;/strong&gt;&#xA;How many crew?  How many PAX?  Level of comfort (utilitarian - R22, or comfortable - Long Ranger).  Fuel load.  Engine and gearbox size.  Cargo and other payload.  Baggage stowage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;What limits the maximum size?&lt;/em&gt;&lt;/strong&gt;&#xA;Weight.  Profile drag.  Cost to manufacture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Non-performance considerations.&lt;/em&gt;&lt;/strong&gt;  Parking; hangar space required.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-03-21T09:42:26.617" LastActivityDate="2015-03-21T09:42:26.617" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13287" PostTypeId="2" ParentId="13202" CreationDate="2015-03-16T22:45:15.130" Score="1" Body="&lt;p&gt;Honestly, I never cared about the minuscule amount of lift generated on the wing by the turning propeller. It's not the lift you need to worry about; it's the angle of attack. When I flew multi-engine prop planes, there was a reason that one of the engines was considered the critical engine (ie the one that most affects the handling of the aircraft) A descending propeller blade creates more thrust than an ascending one (p-factor). And since you want the thrust to be as close to the front or back of the center of gravity as possible to prevent yawing around the CG, you'd prefer to have that descending blade as close to the middle of the aircraft as possible. Torque can play a part with a big engine (like the old Merlins), but the p-factor usually tends to be the bigger issue. Peter is right, you do tend to roll into the failed engine, which can be pretty bad if you don't or worse can't stop it (angle of attack again). You're already doing bad things to the aerodynamics of the aircraft operating on one engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how the aerodynamics of this specific aircraft were, but asymmetrical thrust is asymmetrical thrust no matter the aircraft. The last thing you want to do is stall like that. &lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2015-03-16T22:45:15.130" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13288" PostTypeId="2" ParentId="1320" CreationDate="2015-03-16T23:24:41.093" Score="-1" Body="&lt;p&gt;Calling an AME is the official word.  You can get a pretty good idea of what he's likely to tell you from &lt;a href=&quot;http://leftseat.com/medcat1.htm&quot; rel=&quot;nofollow&quot;&gt;this page&lt;/a&gt; at &lt;a href=&quot;http://leftseat.com/&quot; rel=&quot;nofollow&quot;&gt;LeftSeat.com&lt;/a&gt; -- so if that page says that X isn't approved but Y typically is, that's probably a good starting point for where to start the discussion with a &quot;real&quot; doctor if you're about to be given a prescription.  (Not knocking AME's, but many pilots have the doctor they see when they're sick, separate from their AME.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, nothing on the internet carries as much weight as what your AME tells you, so consider this advice worth what you paid for it!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-16T23:24:41.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13289" PostTypeId="1" CreationDate="2015-03-17T00:31:21.607" Score="-2" ViewCount="181" Body="&lt;p&gt;Where can I purchase the air diffuser located in the overhead compartment of each passenger aircraft seat? I need them for a non aviation application. Thanks &lt;/p&gt;&#xA;" OwnerUserId="7660" LastEditorUserId="774" LastEditDate="2015-03-17T00:55:34.630" LastActivityDate="2015-03-17T04:13:40.517" Title="Where can I purchase air diffusers" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-03-17T07:38:59.543" ContentLicense="CC BY-SA 3.0" />
  <row Id="13290" PostTypeId="2" ParentId="12199" CreationDate="2015-03-17T02:57:02.007" Score="1" Body="&lt;p&gt;It never hurts to bring your sunglasses along. Before getting in the plane, you'll do a visual inspection of the aircraft on the ground by walking around it and looking at things like flaps, ailerons, lights, etc. This usually happens on the ramp which is out in the open so it's an excellent time to gauge whether to wear your sunnies for the flight or not. At least, that's what I do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It isn't that different from driving a car (or even better - riding a motorbike) out in open countryside, it depends mostly on the brightness of the day, the season, and how low the sun is in the sky. Not all planes have sun visors, so you'll definitely want your sunnies if the sun is low in the sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If you plan to do a lot of flying&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.arpansa.gov.au/radiationprotection/factsheets/is_Sunglasses.cfm&quot; rel=&quot;nofollow&quot;&gt;AS/NZS 1067:2003&lt;/a&gt; requires all sunglasses to meet minimum standards for glare, UV protection and colouration. All sunglasses sold are required to meet the standard. If you're in another country and plan to do a lot of flying, you'll want to check what laws apply to sunglasses (if any) and what UV and glare protection is provided by the glasses you intend to use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.productsafety.gov.au/content/index.phtml/itemId/973556&quot; rel=&quot;nofollow&quot;&gt;hazards&lt;/a&gt; associated with repeat, high-UV sun exposure to the eyes include inflammation, cataracts, eyelid cancer, retina degeneration and impaired night vision, so it's well worth protecting your vision with good quality UV blocking sunglasses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Enjoy your flight!&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="2693" LastEditDate="2015-03-18T00:30:17.513" LastActivityDate="2015-03-18T00:30:17.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13291" PostTypeId="2" ParentId="13289" CreationDate="2015-03-17T04:13:40.517" Score="2" Body="&lt;p&gt;The technical name appears to be &quot;Eyeball Air Vent&quot;. A &lt;a href=&quot;https://www.google.com/search?q=eyeball+air+vent&quot; rel=&quot;nofollow noreferrer&quot;&gt;Google search&lt;/a&gt; turned up a number of hits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an aluminum product from &lt;a href=&quot;http://www.21stcentury-usa.com/aveo/misc/airvent/&quot; rel=&quot;nofollow noreferrer&quot;&gt;one manufacturer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kpZAf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a plastic model more in line with what you'd see on an airliner, from a &lt;a href=&quot;http://www.aircraftspruce.com/catalog/appages/plasticeyeball2.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;different seller&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/poqxG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1844" LastActivityDate="2015-03-17T04:13:40.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13294" PostTypeId="1" CreationDate="2015-03-17T11:48:07.153" Score="0" ViewCount="72" Body="&lt;p&gt;I am trying to compare a VASI-4 light system with a PAPI lights. I know that 2White-2Red is the pattern that indicates that the aircraft is on the glideslope; more reds mean lower and more white means higher than the desired glideslope height. With relations to that, how should the VASI lights be on a correct/incorrect approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. My question is specific to VASI-4 light system aka 2-bar VASI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE&lt;/strong&gt; I found &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0201.html&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; from FAA that may very well be the answer, but an explanation would be great.&lt;/p&gt;&#xA;" OwnerUserId="2695" LastEditorUserId="2695" LastEditDate="2015-03-17T12:43:29.837" LastActivityDate="2015-03-17T12:43:29.837" Title="Light indication of a 2-bar system while on the correct glideslope?" Tags="&lt;vasi&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-03-17T13:06:33.463" ContentLicense="CC BY-SA 3.0" />
  <row Id="13295" PostTypeId="1" AcceptedAnswerId="13296" CreationDate="2015-03-17T12:25:56.167" Score="9" ViewCount="891" Body="&lt;p&gt;After reading about &lt;a href=&quot;http://en.wikipedia.org/wiki/Aerial_refueling&quot;&gt;mid-air refueling&lt;/a&gt; and watching &lt;a href=&quot;http://en.wikipedia.org/wiki/The_Perfect_Storm_(film)&quot;&gt;The Perfect Storm&lt;/a&gt;, I have a question: is there a special procedure to observe when performing an in-flight refueling in the rain?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: I heard the tanker pilot says something like &quot;we have a wet hose&quot;. Is this phrase common?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="22726" LastEditDate="2021-01-09T02:00:07.150" LastActivityDate="2021-01-09T02:00:07.150" Title="Is there a special procedure for mid-air refueling in the rain?" Tags="&lt;military&gt;&lt;weather&gt;&lt;mid-air-refueling&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13296" PostTypeId="2" ParentId="13295" CreationDate="2015-03-17T15:00:51.077" Score="9" Body="&lt;p&gt;If you're &lt;a href=&quot;https://en.wikipedia.org/wiki/Visual_meteorological_conditions&quot; rel=&quot;noreferrer&quot; title=&quot;VMC&quot;&gt;VMC&lt;/a&gt; and simply have rain falling, the procedure doesn't change, and it isn't a big deal (talking fixed wing refueling with a boom here; other communities' procedures/capabilities may be different).  The receiver's windshield will have some amount of rain hitting it, but if it isn't particularly heavy rain then he should still be able to do the AR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the visibility is really bad because of the rain, or if you're getting into &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;noreferrer&quot; title=&quot;IMC&quot;&gt;IMC&lt;/a&gt;, then that's the situation you have, irrespective of rain falling or not, and obviously you'd rather have better conditions for doing the refueling.  Going IMC momentarily while you're hooked up may not be a big deal, as you can still see the tanker, but if you lose sight then the first priority is to get positive separation between the two aircraft.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="8375" LastEditDate="2017-08-18T01:48:20.307" LastActivityDate="2017-08-18T01:48:20.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13297" PostTypeId="2" ParentId="7629" CreationDate="2015-03-17T15:13:01.607" Score="4" Body="&lt;p&gt;Every operator has their own procedures, precautions, and &quot;the way they do things.&quot;  Sometimes these may differ based on who is doing the refueling -- the airline's own personnel or contractors, as opposed to somebody who is less of a &quot;known quantity&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is described above sounds very different from what generally happens when US airlines refuel.  To the extent that you want to have emergency evacuation capability in case something goes wrong during the fueling, keeping doors that aren't connected to a jetbridge or airstairs open is UTTERLY counterintuitive.  The door OPEN means you can't deploy the slide quickly.  Closed with the slide armed is generally preferred, IF you don't have a jetway/airstairs connected to facilitate evacuation.  With routine refueling between flights, US carriers typically consider the jetbridge by itself adequate, and the doors aren't armed.  (This is to avert the risk of a catering truck pulling up to an armed door -- opening a door &amp;amp; getting a face full of evacuation slide is a bad day for everybody involved!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;seatbelts off&quot; instruction seems pretty gratuitous as well -- the time it takes to release a seatbelt is inconsequential compared to the time it takes a bunch of people to exit an airplane -- even with great urgency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, every operator has &quot;the way they do things.&quot;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-17T15:13:01.607" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13298" PostTypeId="1" AcceptedAnswerId="13299" CreationDate="2015-03-17T20:38:14.490" Score="15" ViewCount="2616" Body="&lt;p&gt;If it is possible for a General Aviation flight to land at Reagan National Airport, what would you have to do? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's not, what kind of security clearance do commercial carriers and their pilots have to go though in order to land there?  &lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="64" LastEditDate="2015-03-18T23:14:17.890" LastActivityDate="2015-03-18T23:14:17.890" Title="Is it possible to get permission for a GA flight to land at Reagan National Airport?" Tags="&lt;general-aviation&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13299" PostTypeId="2" ParentId="13298" CreationDate="2015-03-17T21:19:38.220" Score="18" Body="&lt;p&gt;The TSA operates the &lt;em&gt;DCA Access Standard Security Program&lt;/em&gt; (DASSP), which allows general aviation flights originating at designated &lt;a href=&quot;http://www.tsa.gov/sites/default/files/assets/pdf/Intermodal/dassp_gatewaylist_3-21-2013.pdf&quot;&gt;gateway airports&lt;/a&gt; to fly into DCA, however &lt;a href=&quot;http://www.tsa.gov/stakeholders/security-programs-and-initiatives&quot;&gt;there are many restrictions in place&lt;/a&gt;, some of the most significant being:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You will need an FAA &lt;a href=&quot;https://www.fly.faa.gov/ecvrs/index.html&quot;&gt;&quot;reservation slot&quot;&lt;/a&gt; to fly in to DCA&lt;br&gt;&#xA;(This is required for all unscheduled flights into DCA)&lt;/li&gt;&#xA;&lt;li&gt;You will need to submit a flight manifest &amp;amp; undergo TSA passenger/baggage screening&lt;/li&gt;&#xA;&lt;li&gt;The flight crew will need to be cleared by the TSA (fingerprint/background check)&lt;/li&gt;&#xA;&lt;li&gt;You will need to carry an &lt;a href=&quot;http://www.tsa.gov/about-tsa/armed-security-officer-program&quot;&gt;Armed Security Officer&lt;/a&gt; onboard&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So the answer is &quot;Yes, you can do it, but you probably don't want to.&quot;&lt;br&gt;&#xA;It also makes no sense to do it in something like a Cessna 172 as you're giving up at least one seat for the security officer. The program is really geared toward larger aircraft (business jets, etc.) transporting executives with a business reason to be in DC, like testifying before Congress.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-03-17T21:27:03.907" LastActivityDate="2015-03-17T21:27:03.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13300" PostTypeId="2" ParentId="2225" CreationDate="2015-03-17T21:47:22.550" Score="8" Body="&lt;p&gt;As already answered, the zigzag is a &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_extension#Dogtooth_extension&quot; rel=&quot;noreferrer&quot;&gt;dogtooth extension&lt;/a&gt; or leading-edge extension on the outboard portion of the wing. It forces the airflow over the wing into a vortex, preventing spanwise flow outward along the wing at high angles of attack. A lot of modern designs incorporate them, including the horizontal tail of the F-15 Eagle, because they often have a side benefit of increasing airflow over the ailerons and increasing control.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To answer the second part of your question (&lt;em&gt;why do only some Hawker Hunters have this feature?&lt;/em&gt;): the dogtooth extension wasn't incorporated into the design until the &lt;strong&gt;F.6&lt;/strong&gt; variant. Wikipedia's &lt;a href=&quot;http://en.wikipedia.org/wiki/Hawker_Hunter_variants&quot; rel=&quot;noreferrer&quot;&gt;list of Hawker Hunter variants&lt;/a&gt; mentions it in a couple of entries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the earlier models didn't have it; at some point the designers and aerodynamicists working on the Hunter tested it out.  Once they figured out that it was an improvement, they would have made the necessary changes to the production line to make it standard on all late-model aircraft built.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-03-17T21:47:22.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13301" PostTypeId="2" ParentId="8786" CreationDate="2015-03-18T01:00:36.233" Score="18" Body="&lt;p&gt;I am an ex-military pilot and retired airline pilot who is still an active pilot in general aviation.  The simple answer is that single seat and tandem seat cockpits are set up with the throttle and trim on the left, so that the stick has to be handled with the right hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a few exceptions side by side cockpits have wheels and the throttle and trim are between the seats so that the pilot in the left seat, usually the pilot in command, uses his left hand on the wheel and the other pilot uses his right hand on the wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I never have trouble switching back and forth, but some people do.&lt;/p&gt;&#xA;" OwnerUserId="7671" LastEditorUserId="11671" LastEditDate="2020-04-22T20:44:10.020" LastActivityDate="2020-04-22T20:44:10.020" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13302" PostTypeId="1" AcceptedAnswerId="13309" CreationDate="2015-03-18T03:12:30.200" Score="5" ViewCount="5669" Body="&lt;p&gt;I'm learning to fly in a C152 and I've found the fuel calculation to be a little ambiguous. Based on information from my instructor, Internet and the Cessna 152 Information Manual (1980), I've home cooked the following formula and wanted to run it by the community for some verification. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this is an appropriate use of this forum and please excuse my newb-ness. Here's my formula:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Fuel Required =&#xA;    5.6L unusable +&#xA;    5L run-up and taxi +&#xA;    24L/hour flight (rich) +&#xA;    18L (45 minute) reserve&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Based on this formula, a one hour lesson conducted in the training area and below 3,000 feet AMSL requires a minimum of 52.6 litres in the tanks, calculated as follows:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;5.6L unusable + 5L run-up &amp;amp; taxi + 24L flight + 18L reserve = 52.6L total&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Or 26.3L in each tank. Since we're measuring fuel by the surprising method of dipping a stick in the tank, I'm realistically looking for around 25L per tank, and maybe topping it up to 30 per tank to be on the safe side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this correct and reasonable?&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="65" LastEditDate="2015-03-18T15:06:20.577" LastActivityDate="2015-03-18T16:15:37.620" Title="How can I correctly calculate fuel for a Cessna 152?" Tags="&lt;fuel&gt;&lt;refueling&gt;&lt;cessna-152&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13303" PostTypeId="2" ParentId="13093" CreationDate="2015-03-18T03:27:46.717" Score="5" Body="&lt;p&gt;Military aircraft are designed to maximize performance, while commercial airliners are designed to maximize reliability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's not to say that reliability is unimportant for the military aircraft or that performance is unimportant for the airliners, but when almost everything is done and the last tradeoff is considered, the military jet can accept a little more maintenance in return for a little better performance, while the airliner will probably sell better with better reliability &amp;amp; the ability to go longer between maintenance down-time, even at the cost of the last 0.2% better performance/weight/economy/etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The assumption for military aircraft, fighters &amp;amp; bombers in particular, is that they'll finish the day back at their base, and they CAN be worked on for several hours before they're launched again.  (Generality here -- yes higher tempo ops are possible, but it's the exception not the rule.)  Airliners, on the other hand, typically will fly for days between maintenance checks (beyond adding oil, checking tire pressure, and maybe swapping a particular broke part) -- and that's what's desirable because that's how the airplane makes the most money.  So that ability to go for so long between maintenance checks is built in because that's what the customer (the airlines) demands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could you get more performance out of an airliner if you were willing to accept more maintenance costs?  Sure, but it wouldn't be worth it to the airlines.  At the extreme, the Concorde, for all its cool factor, was an economic disaster, even though its performance was superlative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The military aircraft have redundant systems in order to survive -- limp back to base.  Commercial aircraft have redundant systems in order to be able to be dispatched again -- stay in service until repairs can be performed.  (Obviously, not everything can be deferred; some things ground the airplane &amp;amp; have to be fixed before it flies again... but a LOT of stuff in the airliner can be deferred &amp;amp; you still have redundant capability to land safety even if another system goes down.)  As an example, the F-16 was (may still be) single-INS + single-FMS.  The system works or you don't launch.  Modern airliners have two or three INS's and FMC's -- dispatch with one INS inop is possible (probably day VMC only), and dispatch with one FMC inop has minimal limitations (no long overwater legs, essentially).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different missions drive different design priorities, and that in turn shows up as differing levels of maintenance that's required.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-18T03:27:46.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13304" PostTypeId="1" CreationDate="2015-03-18T05:44:14.990" Score="5" ViewCount="781" Body="&lt;p&gt;I have read the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3306/why-are-push-propellers-so-rare-yet-they-are-still-around&quot;&gt;post&lt;/a&gt; where it describes about the push and pull configurations of the engine, advantages/dis-advantages in them but not the purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen images of a figter where the propellers are placed both at the front as well as back, such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Do_335&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dornier Do 335&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X4PYc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://de.wikipedia.org/wiki/Datei:Dornier_Pfeil2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiPedia&lt;/a&gt; - Author: Ad Meskens)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later there are some downsized planes which are remotely controlled vehicles like the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Atomics_MQ-9_Reaper&quot; rel=&quot;nofollow noreferrer&quot;&gt;MQ-9 Reaper&lt;/a&gt; where the propellers are placed at the rear, &lt;a href=&quot;http://en.wikipedia.org/wiki/Miniature_UAV&quot; rel=&quot;nofollow noreferrer&quot;&gt;Miniature UAV&lt;/a&gt; have the props in the front (sometimes even the direction of the propeller also vary)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the size which makes the difference or the purpose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also what was the scenario due to which the designers had to go in for a varying propellers why not stick to the simple front facing propellers (which are placed either on the wings or in the front why to go for propellers with backward design/rear placed)?&lt;/p&gt;&#xA;" OwnerUserId="3012" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-05-07T15:55:07.290" Title="What are the factors considered while placing a propeller on a plane?" Tags="&lt;propeller&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ClosedDate="2015-03-18T09:38:40.837" ContentLicense="CC BY-SA 3.0" />
  <row Id="13305" PostTypeId="2" ParentId="13304" CreationDate="2015-03-18T06:11:32.577" Score="2" Body="&lt;p&gt;It is the purpose. Each configuration has it's own advantages and disadvantages. This is already explained in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3306/&quot;&gt;Why are push-propellers so rare, yet they are still around?&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/a/3320/524&quot;&gt;this answer&lt;/a&gt; in particular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of Do335, the reason is that they wanted two engines, but keep the engines on the centreline. This results in lower drag due to lower frontal area and better manoeuvrability due to lower moment of inertia as the engines are closer to centre of gravity. The pusher propeller itself reduces the manoeuvrability somewhat though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of MQ-9 it simply matter of providing space and clear view for the radar and cameras in front while the reduced manoeuvrability does not matter much in this case.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-03-18T06:11:32.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13308" PostTypeId="2" ParentId="13302" CreationDate="2015-03-18T06:57:04.717" Score="-10" Body="&lt;p&gt;Normally, the practice in my experience is to fill the tanks in all cases to minimize the situations in which fuel starvation would be possible. For this reason, in the United States most trainers are rented wet. Exact fuel calculations usually are only relevant when flying cross country, and even then using generous reserves is a wise practice. During a lesson there are usually lots of unplanned activities, like the ole 30 minute run-up, waiting on the taxiway to take off behind 3 other aircraft that have some kind of problem, and in-flight distractions, so cutting it close on fuel is a bad idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second issue is that if you fill the tanks only for what you need, any additional rentals will each have to fill the tanks, too, which can cause delays and throw off the rental schedule. For example, let's say the C152 is rented 4 times that day. If each pilot only filled the tanks for what he/she needed, then the fuel truck would have to come 4 times. Sometimes it takes a while for the fuel truck to arrive. If you need to taxi to a pump, that is another delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all of these reasons, the normal practice for a student is to fill the tanks. If you are the owner/operator of the aircraft, you may choose to parsimoniously load the fuel you absolutely require, and save some money, but it does not sound from your post as though this is the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;IMPORTANT CAVEAT: Overweight&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft would be overweight if you were to fill the tanks, then the above advice obviously cannot be followed. In that case, assuming it is a rental, the logical thing to do is two computations: your estimated need (which are already doing), and the maximum possible. If the need is greater than the maximum possible, you will need to change your flight plan. If the maximum is significantly greater than the need (enough for two or more lessons), then you should fill to the maximum, so that the next student does not have fill the tank, too. If the maximum is only moderately over the need, and the next student will have to fill it anyway, then you may as well fill it just to your calculated need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as your calculations themselves are concerned, they seem right, aside from the use of the evil French units of measure.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-03-18T16:15:37.620" LastActivityDate="2015-03-18T16:15:37.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13309" PostTypeId="2" ParentId="13302" CreationDate="2015-03-18T07:12:43.147" Score="8" Body="&lt;p&gt;The short answer is: Yes, your calculation is reasonable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel consumption values are not an exact science, they are average values and rounded in many cases or based on pilot experience. Using &lt;code&gt;24L/hr&lt;/code&gt; in your example for traffic patterns is the right assumption, as you will most likely remain in rich configuration. Even if you lean a bit within the pattern, you would not gain enough fuel efficiency to offset these &lt;code&gt;24L/hr&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your &lt;code&gt;5L&lt;/code&gt; run-up and taxi obviously depends on the airport you are based at or use the formula at. If this value was your calculation for a smaller airfield, you might need to adapt your formula when flying to larger regional airports or airports with high-traffic, where your taxi time could be significantly longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Be reasonable however with topping up your values. Going from &lt;code&gt;52.6L&lt;/code&gt; to &lt;code&gt;60L&lt;/code&gt; is the equivalent of &lt;code&gt;5.3KG&lt;/code&gt;, which you will need to consider in your weight and balance calculation.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-18T07:27:00.677" LastActivityDate="2015-03-18T07:27:00.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13310" PostTypeId="2" ParentId="13304" CreationDate="2015-03-18T07:26:16.520" Score="4" Body="&lt;p&gt;The biggest factor is familiarity: What has worked before?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other factors are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Propeller size: Slow-turning propellers driven by powerful engines have a big diameter. This is desirable because it improves efficiency. However, now the propeller cannot be placed behind the wheels if the rotation angle should not be restricted.&lt;/li&gt;&#xA;&lt;li&gt;Engine location: Driveshafts cost weight and run the risk of resonance problems, so the propeller should be directly in front or at the back of the engine. The engine location is dictated by the desired mass distribution, cooling, the pilot's field of vision, and space demands.&lt;/li&gt;&#xA;&lt;li&gt;Interference: This includes all factors like prop wash and swirl. Putting the propeller ahead of control surfaces or flaps improves their effectiveness at low speed. Conversely, the increased flow speed increases friction drag on the surfaces wetted by the propeller's slipstream.&lt;/li&gt;&#xA;&lt;li&gt;Stability: The propeller acts like an additional small wing and creates lift and side force when not exactly perpendicular to the inflowing air.&lt;/li&gt;&#xA;&lt;li&gt;Engine-out performance: Multi-engined aircraft should still be flyable with one dead engine. This is an interaction between propeller location and control surfaces, and to minimize drag, those control surfaces should be as small as possible. Thus, the propeller should be close to the center of gravity.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The rear propeller is more efficient, because it helps to prevent separation on the surfaces ahead of it, and its slipstream will not increase the friction drag. However, integrating a propeller at the back of an aircraft is hard, so few designs (apart from those in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3306/why-are-push-propellers-so-rare-yet-they-are-still-around/3320#3320&quot;&gt;this answer&lt;/a&gt;) made use of it. Notable examples are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A range of &lt;a href=&quot;http://en.wikipedia.org/wiki/Airco_DH.2&quot; rel=&quot;nofollow noreferrer&quot;&gt;British fighters&lt;/a&gt; during the early years of WW I, when only the Germans had mastered the technology of synchronized machine guns.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Zeppelin&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zeppelin&lt;/a&gt; airships. Their gondolas had rear-mounted propellers.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_B-36_Peacemaker&quot; rel=&quot;nofollow noreferrer&quot;&gt;Convair B-36&lt;/a&gt;. The pusher location in the wing was selected for better efficiency, but created cooling problems for the engines.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/LearAvia_Lear_Fan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Learfan&lt;/a&gt;, started during the first oil shock and designed for efficiency. Two PT-6 drove a single pusher propeller.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piaggio P-180 Avanti&lt;/a&gt;, which was designed a few years later and much for the same reason as the Learfan.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;http://en.wikipedia.org/wiki/Claude_Dornier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Claude Dornier&lt;/a&gt; had used two engines in one engine pod, driving a propeller each at the front and at the back, as early as 1915, when he worked for Zeppelin on a giant metal flying boat. This became a common theme on many Dornier aircraft, especially the flying boats, and on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Zeppelin-Staaken_R.VI&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zeppelin Staaken&lt;/a&gt; giant bombers. The last example of this range is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dornier_Seastar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dornier Seastar&lt;/a&gt;, designed in the late 1970s.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-05-07T15:55:07.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13312" PostTypeId="2" ParentId="13269" CreationDate="2015-03-18T12:31:51.630" Score="1" Body="&lt;p&gt;By every recommendation I've ever seen 48hrs is extremely liberal for recreational divers.  I went on my first dive trip with my parents when I was 12 years old and our rule was to quit diving at least 24 hours before your flight.  It is related to pressure and it all depends on how much time you've spent and at what depth.  The deeper you go, the quicker you build nitrogen in your tissues and the more time you'll need to allow for that nitrogen to dissipate.  If you spend enough time at depth there is even a recommendation to make a safety-stop during your dive (typically 5-15 minutes at about 30ft for recreational diving) as a best-effort to avoid the bends and surface decompression.  The U.S. Navy created classification charts that indicate your relative nitrogen absorption.  Here are some resources hosted by NOAA, one of them being a PDF specifically covering this topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ndc.noaa.gov/dp_forms.html&quot; rel=&quot;nofollow&quot;&gt;http://www.ndc.noaa.gov/dp_forms.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ndc.noaa.gov/pdfs/USNDeco3.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.ndc.noaa.gov/pdfs/USNDeco3.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7669" LastActivityDate="2015-03-18T12:31:51.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13313" PostTypeId="1" CreationDate="2015-03-18T13:31:12.957" Score="13" ViewCount="7450" Body="&lt;p&gt;I'm a curious high school student. Why is there a compressor after the first heat exchanger in an &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_cycle_machine&quot;&gt;air cycle machine&lt;/a&gt;? I've read that compressing the cold air is for the cause of efficiency because compressing hot air uses much more work than cold air, and the effect of this is that the compressed air temperature increases. But if so, why compress at all when the air itself is going to be cooled again in the second heat exchanger?  Why not leave the compressor and place the turbine as it is from the ACM?&lt;/p&gt;&#xA;" OwnerUserId="7679" LastEditorUserId="62" LastEditDate="2015-03-18T13:33:50.093" LastActivityDate="2020-06-15T19:58:03.927" Title="Why is there a compressor in an air cycle machine?" Tags="&lt;aircraft-systems&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13314" PostTypeId="2" ParentId="13313" CreationDate="2015-03-18T13:45:32.090" Score="6" Body="&lt;p&gt;Because there is an expansion stage, the energy of the compressed air can be used to run a second compressor. Doing this allows to cool the precompressed air before it is fed to the second compressor, thus improving overall efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same reason, some turbocharged engines use two turbocharging stages with an intercooler between the compressor stages. It keeps the volume of air low and allows for smaller, more efficient turbochargers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could also extract the air at a later stage of the engine compressor, cool it and expand it in a diffusor, but then the engine compressor has to do more work and the cooler needs to be bigger due to the higher temperature and lower density of the compressed air. But somehow you still need to shed the pressure energy in the air, and running it through a turbine is an ideal way to achieve this.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-18T20:22:05.673" LastActivityDate="2015-03-18T20:22:05.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13315" PostTypeId="1" AcceptedAnswerId="13316" CreationDate="2015-03-18T14:59:23.400" Score="2" ViewCount="596" Body="&lt;p&gt;This made the news few days ago: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;British Airways flight to Dubai forced to return to Heathrow due to 'smelly poo in toilet'&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As can be seen at &lt;a href=&quot;http://www.telegraph.co.uk/news/aviation/11472627/British-Airways-flight-to-Dubai-forced-to-return-to-Heathrow-due-to-smelly-poo-in-toilet.html&quot; rel=&quot;nofollow&quot;&gt;The Telegraph&lt;/a&gt; and &lt;a href=&quot;http://www.independent.co.uk/news/uk/pungent-smell-from-toilet-causes-ba-plane-to-return-to-heathrow-10108519.html&quot; rel=&quot;nofollow&quot;&gt;The Independent&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Made me wonder: isn't it possible to recycle the air from the cabin and perhaps isolate the toilet? This could lead to a whole new series of chemical attacks on long flights.&lt;/p&gt;&#xA;" OwnerUserId="616" LastEditorUserId="97" LastEditDate="2015-04-22T00:23:34.420" LastActivityDate="2015-04-22T00:23:34.420" Title="Is air in the toilet isolated, to prevent seeping into the cabin?" Tags="&lt;cabin-design&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13316" PostTypeId="2" ParentId="13315" CreationDate="2015-03-18T15:55:58.317" Score="5" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If someone can get chemicals on board a flight, they can also get a bomb on. Bombs are easier to make and more effective. Better air-conditioning won't help here, better security will.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is possible to isolate the toilet... but the problem apparently wasn't just inside the toilet. The toilet isn't pressure sealed, so some smell will escape regardless. It's impossible to completely seal the toilet from the rest of the aircraft, and could be potentially dangerous if it was&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft does introduce fresh air into the cabin, but the compressors to do so only have a fixed capacity. The capacity of these could be increased, but at the price of extra weight, fuel consumption and cost, it's not worthwhile for the 1 time in 100 million that a flight has to turn around for this reason. Even with higher capacities, it's not possible to just constantly flush the cabin air - and remember that all that air needs to be compressed (to maintain pressure) heated, and filtered. All of that costs more money, and adds more complexity, weight etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-03-18T15:55:58.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13317" PostTypeId="1" CreationDate="2015-03-18T16:19:44.043" Score="3" ViewCount="403" Body="&lt;p&gt;How quickly would a commercial airline be able to integrate significant advances in technology into its fleet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically I am interested in large commercial airlines and advances in technology that would substantially increase the efficiency of fuel consumption in passenger aircraft, but I don't have enough of a background in commercial aviation to make an educated guess and have not been able to find a comparable historical example. If someone could provide me with either it would be much appreciated.&lt;/p&gt;&#xA;" OwnerUserId="7683" LastActivityDate="2015-03-18T22:01:51.143" Title="How quickly could a commercial airline integrate advances in technology into its fleet?" Tags="&lt;commercial-aviation&gt;&lt;fuel&gt;" AnswerCount="4" CommentCount="4" ClosedDate="2015-03-19T09:29:23.513" ContentLicense="CC BY-SA 3.0" />
  <row Id="13318" PostTypeId="2" ParentId="13317" CreationDate="2015-03-18T16:30:56.387" Score="3" Body="&lt;p&gt;If pressed (each plane is grounded until it is installed)? As fast as it's maintenance guys can pump them out per plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing so would require getting the plane to the shop and having the mechanics installing the &quot;advance&quot; which could take a few days. They would then also take the chance to do some &lt;a href=&quot;https://aviation.stackexchange.com/a/13085/609&quot;&gt;of the regular checks&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not then the install would be scheduled along with the other &lt;a href=&quot;https://aviation.stackexchange.com/a/13085/609&quot;&gt;regular check&lt;/a&gt; already planned in its lifetime depending on how labour intensive the installation is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before all that can actually happen the guys doing the install must be trained and the supervisors must be able to certify the installation, that will also take time.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-03-18T16:49:00.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13319" PostTypeId="2" ParentId="13317" CreationDate="2015-03-18T16:31:07.693" Score="2" Body="&lt;p&gt;Immediately in some cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, a large carrier will have a heterogeneous fleet in which the most recently purchased aircraft will be more performant and fuel efficient than the older aircraft. A carrier can generally &quot;buy&quot; fuel efficiency simply by selling older airframes and buying new ones with new engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way carriers can improve fuel efficiency is by how they load the airframe. Seats and other fixtures onboard are removable and the carrier can reconfigure aircraft in various way and improve the way the equipment is constructed to make it lighter. Carriers are always looking for upgrades that will lighten the load or balance the load better to improve fuel efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also computational ways to fly more efficiently. For example, if the flight plan and route planning can make use of winds aloft more efficiently significant fuel savings can be realized. Advanced software can also be used to tune engines or fly the aircraft so that engines use fuel more efficiently.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-18T16:31:07.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13320" PostTypeId="2" ParentId="13317" CreationDate="2015-03-18T18:18:06.973" Score="2" Body="&lt;p&gt;I would try to give some structure to the answer. Firstly, take into account that any technological innovation on the airplane itself it is not performed by the airline, is done by the airplane manufacturer like in car industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For giving you a more concrete answer I would divide in three:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Only renewing improving the fleet by a new one. A way to get the latest technology is just by selling to other airlines or transport companies the old models and buy new airplanes. Typical life span of a airplane is aroud 20-30 years, so that will be how often airlines do that.&lt;/li&gt;&#xA;&lt;li&gt;Another way is implementing retrofits, airplane manufactures offer some improvements as retrofit of the airplane like the &lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/sharklet-retrofit-sales-gain-momentum/&quot; rel=&quot;nofollow&quot;&gt;A320 sharklet&lt;/a&gt;. However you need a business case, not all retrofits are implemented because they are not interesting, apart from the cost of buying from the manufacturer the retrofit the airline will have the airplane in ground during the retrofit. Usually to maximize the business case the airline waits until a complete overhaul (revision) is perform on the airplane to take the advantage is already grounded.&lt;/li&gt;&#xA;&lt;li&gt;Finally: as soon as possible. Just take a look to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems&quot; rel=&quot;nofollow&quot;&gt;recent battery issues on B787&lt;/a&gt; airplanes were grounded during a long period to avoid reducing safety standards. When this kind of situations happen, airlines try to implement technology changes (or just modifications) as soon as possible. Business case is really possitive...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Finally, I think the right question is... who pays the modification in the last situation?&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-03-18T18:18:06.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13321" PostTypeId="2" ParentId="13313" CreationDate="2015-03-18T20:18:10.633" Score="19" Body="&lt;p&gt;If I understand your question correctly, you don't really understand how the ACM works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea of an ACM is to create 'cool' air. Especially on the ground (imagine landing on your tropical holiday destination), this means that the air must sometimes be made &lt;strong&gt;cooler&lt;/strong&gt; than the outside (ambient) temperature. The second law of thermodynamics (and in this case, the law of common sense) states that you can't just cool your air against the warm ambient air, so you will need to do some special tricks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the special trick is compression. You compress the air, which will make it quite hot (&lt;strong&gt;increase the temperature&lt;/strong&gt;) (search for &lt;em&gt;adiabatic compression&lt;/em&gt; on the internet). Then, this hot air can of course easily be cooled against ambient air, which happens in the second heat exchanger. In fact, the hotter the air after compression is, the more heat is exchanged in the second heat exchanger. This means the heat exchanger can be made smaller, which is especially useful since air-to-air heat exchangers are &lt;em&gt;inefficient&lt;/em&gt; and thus relatively &lt;em&gt;big&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, you expand your air again, which will cool it (&lt;strong&gt;decrease the temperature&lt;/strong&gt;). However, since you already cooled it down in the second heat exchanger, it will now be cooler than when it originally encountered the compressor! This makes sense, since you removed energy from the air in the second heat exchanger. So, this way, you can cool the air down further than would have been possible by a heat exchanger (search for &lt;em&gt;reverse Brayton cycle&lt;/em&gt; on the internet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, this system has two advantages: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It is possible to cool down air beyond ambient temperature, so it functions as 'airco' on the ground or at low altitude.&lt;/li&gt;&#xA;&lt;li&gt;It is possible to cool hot compressed bleed air with a relatively small, light heat exchanger for pressurizing your cabin while not cooking your passengers medium-rare.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2015-03-19T13:25:48.810" LastActivityDate="2015-03-19T13:25:48.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13322" PostTypeId="2" ParentId="13317" CreationDate="2015-03-18T21:50:30.007" Score="4" Body="&lt;p&gt;It depends on the advance. Generally, there are three ways how airliners can be improved:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Operations and procedures: This can be as simple as faster turn-around times so aircraft will be more profitable, or as complicated as &lt;a href=&quot;http://en.wikipedia.org/wiki/Free_flight_(air_traffic_control)&quot; rel=&quot;nofollow&quot;&gt;doing away with airways&lt;/a&gt; which would help to shorten trips, but depends on changes in regulations which have been in place for decades.&lt;/li&gt;&#xA;&lt;li&gt;Better equipment: All parts of an aircraft are designed to be individually replaceable, and swapping old engines for newer, more fuel efficient ones will bring already two thirds of the efficiency benefits of replacing the whole aircraft. Other examples could be less heavy furnishings or more precise instruments. But there are limits, and every change needs to be approved by regulatory authorities.&lt;/li&gt;&#xA;&lt;li&gt;Newer aircraft models: This brings aerodynamics, engines and equipment up to the status quo, and is done by airlines on a regular basis to improve both their attractiveness and their profitability. Examples are &lt;a href=&quot;http://www.singaporeair.com/en_UK/about-us/sia-history/sia-fleet/&quot; rel=&quot;nofollow&quot;&gt;Singapore Airlines&lt;/a&gt;, which pride themselves on an average age of their fleet of just seven years, or &lt;a href=&quot;http://en.wikipedia.org/wiki/Vueling&quot; rel=&quot;nofollow&quot;&gt;Vueling&lt;/a&gt;, which thanks to a recent expansion has lower seat-mile cost than all their competitors.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Generally, the days of dramatic technology advances are long gone. Today, years of research are justified by single-digit percentage advances, and a new development like the A380 is started with a promise of just 15% less seat-mile cost when compared to airliners which are two decades old by the time the new plane is put into service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question directly: Changes which produce meaningful improvements need years of preparation and testing for approval by the authorities. Quick gains are not possible anymore.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-18T22:01:51.143" LastActivityDate="2015-03-18T22:01:51.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13323" PostTypeId="1" CreationDate="2015-03-18T23:16:12.023" Score="7" ViewCount="2826" Body="&lt;p&gt;Military pilots are instructed throughout training that they must learn all checklists off-by-heart (in the RAF anyway). This way things get done much quicker, primarily in the event of an emergency when the immediate actions must be performed like 2nd nature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A recently PPL-qualified pilot friend of mine informed me that he refers to his reference cards for every set of checks. The checks for a Cessna-152 were much much more brief than for military trainers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering what the standard is for general aviation, and whether there is a requirement to learn at least engine-failure immediate actions?&lt;/p&gt;&#xA;" OwnerUserId="7169" LastEditorUserId="65" LastEditDate="2015-03-19T13:22:47.120" LastActivityDate="2015-10-29T19:09:44.400" Title="Is it required to memorize checklists for better efficiency?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;general-aviation&gt;&lt;military&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13324" PostTypeId="2" ParentId="13323" CreationDate="2015-03-18T23:27:43.560" Score="0" Body="&lt;p&gt;I don't know of any standard, but it is definitely a wise idea to learn the emergency procedures very thoroughly. One reason for this is that every flight is different. Even routine stuff like the run-up tends to have some new quirk or difference every time. If you have the checklist down pat, it makes it much easier to deal with whatever unique thing is happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a fire, for example, if you are fumbling with a checklist and do not already know the procedure thoroughly, valuable seconds will be lost while you are reading through the items. You want to know it so well that all you have to do is glance at the item and say &quot;ok now I do this&quot;. In other words, the checklist should just be a reminder to what you already know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the United States there is no absolute requirement to know the checklists thoroughly ahead of time, but an applicant's likelihood of failing a practical test will definitely increase if they don't, because your chance of making a mistake or getting flustered is greater if you do not know the checklist by rote.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I would note that in US practice you MUST use physical checklist or the FAA examiner will fail you in a test. Memory is not considered an acceptable substitute for a physical checklist by the FAA.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-26T23:35:34.850" LastActivityDate="2015-10-26T23:35:34.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13325" PostTypeId="2" ParentId="13323" CreationDate="2015-03-18T23:41:46.663" Score="5" Body="&lt;p&gt;The upside of memorized checklists is that you can execute the checks much more quickly; the downside is that many of the detailed troubleshooting checklists used for non-normal conditions that arise in commercial aviation are much longer than a pilot can reasonably memorize.  However, the idea behind it is sound -- normal checklists are a &lt;em&gt;check&lt;/em&gt;list, not a reference for how to operate the airplane day-to-day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, commercial operators and private pilots use flows (i.e. a series of control movements, sequenced for efficient performance and checklist compliance) in conjunction with their checklists for normal procedures and memory items, and modern (i.e. &quot;glass cockpit&quot;) transport aircraft provide checklist prompts through the ECAM or EICAS display system that are used for non-normal conditions and the non-critical portions of emergency checklists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/a/12713/3825&quot;&gt;this answer&lt;/a&gt; for an excellent example of how an emergency checklist (engine failure) and its matching flow work together in a light aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-18T23:41:46.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13326" PostTypeId="1" AcceptedAnswerId="13328" CreationDate="2015-03-19T02:17:36.457" Score="46" ViewCount="21435" Body="&lt;p&gt;I learned from &lt;a href=&quot;https://aviation.stackexchange.com/questions/13302/how-can-i-correctly-calculate-fuel-for-a-cessna-152&quot;&gt;this question&lt;/a&gt; that a Cessna 152 holds 5.6 litres of fuel that it can't use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would it be designed to hold fuel that it cannot burn, especially since water contamination of fuel is a concern?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-25T16:32:49.157" Title="Why do aircraft have an unusable amount of fuel?" Tags="&lt;aircraft-design&gt;&lt;fuel-tanks&gt;" AnswerCount="5" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13327" PostTypeId="2" ParentId="13326" CreationDate="2015-03-19T04:59:03.943" Score="15" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;especially since water contamination of fuel is a concern?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's one of the reasons. Fuel floats on water, so water collects in the bottom of the tank, along with other gunk. By not taking the last dregs of fuel from the bottom of the tank you avoid putting this stuff into the engine&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="1576" LastEditDate="2015-03-27T03:21:52.707" LastActivityDate="2015-03-27T03:21:52.707" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13328" PostTypeId="2" ParentId="13326" CreationDate="2015-03-19T05:27:26.550" Score="67" Body="&lt;p&gt;Pilot here (with Cessna 152 hours) as well as an engineer who made it most of the way to an Airframe and Powerplant technician license at one point in life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several reasons that conspire to produce 'unusable fuel':&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Fuel tanks on airplanes have complex shapes - they include baffles and other walls (with holes in them) to prevent oscillations from building up during in-flight movement. Sometimes these baffles are even engineered into the tanks late in the design cycle as testing finds oscillation issues. These baffles result in 'geometric trapping' of fuel in nooks and crannies. &lt;/li&gt;&#xA;&lt;li&gt;Drawing fuel from a fuel tank is more complicated in a plane - cars are pretty much flat with minor tilts while airframes can have all sorts of odd and sustained directions that the fuel wants to go due to acceleration. Imagine an extended tilted spiral while descending - that fuel experiences far more lateral acceleration over a longer time period that a car would have. Getting the fuel system to pull fuel out from these different angles is challenging (note that I've picked a non-aerobatic maneuver for which the Cessna 152 of your question is qualified here).&lt;/li&gt;&#xA;&lt;li&gt;All of this is a cost/complexity tradeoff - solutions exist for 1 and 2 above - fighter jets use fuel bladders that have pressure bladders arranged to squeeze the fuel out so that they can get almost all the fuel even at high G-forces and unusual angles. Aerobatic planes have similarly more expensive and complicated systems than the old and cheap Cessna 152.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are other considerations as well, but mostly it comes down to whether the plane in question can justify the cost and effort to get every last drop of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things get even more complicated in rockets - the moon rockets (properly the Saturn 5 although it was an upper stage specifically) had special extra engines called ullage motors whose only job was to give the stage a little boost in space to push the fuel towards the rear of the rocket so that the main motors could draw fuel and start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Addendum edit: @supercat below - the definition of unusable fuel is set by federal aviation regulation part 23, section 959 (&lt;a href=&quot;http://www.flightsimaviation.com/data/FARS/part_23-959.html&quot;&gt;FAR 23.959&lt;/a&gt;) and basically is the worst case under &quot;intended operation&quot; for the particular plane. Since the Cessna 152 is not aerobatically rated, for example, the unused fuel is defined as the fuel level where SOME intended maneuver would be capable of causing a fuel system error. In practice, especially in flat level flight, some of that unusable fuel would be available for use although you are not supposed to plan to use it in your flight planning.&lt;/p&gt;&#xA;" OwnerUserId="7688" LastEditorUserId="-1" LastEditDate="2015-03-20T11:32:39.920" LastActivityDate="2015-03-20T11:32:39.920" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="13329" PostTypeId="2" ParentId="13323" CreationDate="2015-03-19T07:25:21.297" Score="11" Body="&lt;p&gt;In the US the closest thing to a standard, and the requirement (&lt;a href=&quot;https://www.youtube.com/watch?v=LVtNfvqEGuk&quot; rel=&quot;nofollow&quot;&gt;per the FAA's practical test standards&lt;/a&gt;), is that you make appropriate use of checklists.&lt;br&gt;&#xA;As mentioned in that video &quot;appropriate&quot; leaves some room for common sense interpretation (clearly your first course of action if your engine dies in flight should not be to open the operating manual to the &lt;em&gt;Engine Failure In Flight&lt;/em&gt; checklist and begin reading: That would &lt;em&gt;NOT&lt;/em&gt; be &quot;appropriate&quot;).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect most other countries have a similar view on the subject.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as what gets memorized, the checklists for most simple aircraft (for our purposes let's say that's anything with a single piston engine, unpressurized, with 6 seats or less -- your average Piper/Cessna/Citabria/etc.) can be memorized. They're not that long and there's not that many of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time permitting a good pilot will generally still refer to the printed checklist even if they did the entire thing from memory, if only to read off each item and make sure they didn't miss anything.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;More complicated checklists (like what you might find on a 737 or a C-130 for example) will usually have a set of &lt;em&gt;Immediate Action Items&lt;/em&gt; (often called &quot;Red Box Items&quot; because many manufacturers put them inside a big red box at the top of Emergency or Abnormal checklists).&lt;br&gt;&#xA;It's generally expected that the flight crew have the Red Box Items committed to memory and be able to complete essentially on instinct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After completing the Red Box Items all the really important stuff is done, and there is hopefully enough time that it's now &lt;em&gt;appropriate&lt;/em&gt; to pull out the checklist (or Quick Reference Handbook), verify that the Red Box Items have all been done, and run through the rest of the items.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-10-29T19:09:44.400" LastActivityDate="2015-10-29T19:09:44.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13330" PostTypeId="2" ParentId="13326" CreationDate="2015-03-19T09:15:28.197" Score="13" Body="&lt;p&gt;Almost any system that moves liquid around will retain a certain volume. In your case, there are various bends in the pipes and some of those bends go up. Yes, it's gravity-fed but notice the shutoff valve on the floor. Now notice the level of the carburetor. Any fuel below the level of the carb bowl is unusable, as we have no way to push it through the rest of the plumbing without more liquid behind it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we turn to things with a pump the unusable quantity can go up, a lot. The volume of liquid between the pump and the final destination would be considered unusable for the same reason - once the pump is dry we can't move it along anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One restaurant manager I used to know installed a metered drink dispensing system. All the booze is in the (locked) storage room, the bartenders push a button and exactly one ounce comes out of the tap. The only complaint he had was that the system cost $500 to prime, &lt;strong&gt;per item&lt;/strong&gt;, and he had to keep thousands of dollars of &quot;unusable&quot; alcohol on the books.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-03-19T09:15:28.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13331" PostTypeId="1" AcceptedAnswerId="13337" CreationDate="2015-03-19T09:28:32.017" Score="16" ViewCount="7400" Body="&lt;p&gt;So I went on 2 long (total of 16 hours) flights with a major US airline, and they did not provide a free in-flight lunch (grr) during either flight. I had brought a sandwich with me just in case, but when I asked the flight attendant if they could heat it up they said that they did not have microwaves. This was I think a 757 or similar aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I landed I was asked about my trip, the microwave thing came up and was told (by an older person) that airlines did have microwaves and that mothers with children would often ask the flight attendants to warm up bottles of milk for them...?!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now I'm curious, did aircraft used to have microwaves in the past? Were they removed? I &lt;strong&gt;now&lt;/strong&gt; know the food they serve on airplanes is &quot;heated via hot air ovens&quot; but why would there not be a microwave on board? Even if just for crew use?&lt;/p&gt;&#xA;" OwnerUserId="2364" LastEditorUserId="2364" LastEditDate="2015-03-20T04:12:28.740" LastActivityDate="2019-02-19T14:26:45.603" Title="Did commercial airliners have microwave ovens in the past?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;usa&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13332" PostTypeId="1" AcceptedAnswerId="13334" CreationDate="2015-03-19T11:31:18.220" Score="18" ViewCount="5656" Body="&lt;p&gt;One of Leonardo da Vinci's flying machines appears to be a giant auger.  This design would not have exploited Bernoulli's Principle, but rather used the blade's rotation to push the air below it down to keep the craft airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SsHXl.jpg&quot; alt=&quot;da vinci&amp;#39;s aerial screw&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image credit: &lt;a href=&quot;http://commons.wikimedia.org/wiki/Image:Leonardo_da_Vinci_helicopter_and_lifting_wing.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were there any flying machines built like this that actually got off the ground?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: So maybe I have Bernoulli misunderstood, judging from the discussion.  &lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-20T03:56:50.420" LastActivityDate="2020-09-15T18:02:56.837" Title="Were there any successful flying machines that did not rely on Bernoulli's Principle?" Tags="&lt;aerodynamics&gt;" AnswerCount="7" CommentCount="19" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13333" PostTypeId="2" ParentId="13332" CreationDate="2015-03-19T11:51:23.477" Score="17" Body="&lt;p&gt;Air balloons and rockets are two examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air balloons fly by varying the density of the aircraft to lighter&#xA;than air.&lt;/li&gt;&#xA;&lt;li&gt;Rockets fly by redirecting exhaust gas downward.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When the F-35 hovers, it too uses engine exhaust to counter the weight. However, their internal turbines still uses Bernoulli's principle to produce thrust.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/U5rb6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-03-19T13:04:55.930" LastActivityDate="2015-03-19T13:04:55.930" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13334" PostTypeId="2" ParentId="13332" CreationDate="2015-03-19T11:53:28.590" Score="34" Body="&lt;p&gt;How about all lighter-than-air vehicles:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hot air balloons&lt;/li&gt;&#xA;&lt;li&gt;Hydrogen- or helium-filled balloons&lt;/li&gt;&#xA;&lt;li&gt;Airships&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you want to restrict the choice to heavier-than-air vehicles, rockets should still qualify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also include VTOL aircraft which do not rely on their wings during hover, their internal turbo machinery would still use Bernoulli's principle, however, so for me they do not qualify.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-03-19T11:53:28.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13335" PostTypeId="1" AcceptedAnswerId="13336" CreationDate="2015-03-19T12:21:48.397" Score="11" ViewCount="53001" Body="&lt;p&gt;Currently in &lt;a href=&quot;https://goo.gl/maps/jwl0R&quot;&gt;Indianapolis, IN&lt;/a&gt; (19 Mar 2015, ~08:00 EDT -4GMT), there is some sort of big kerfuffle downtown, and I can see 3 helicopters hovering over the near west-side of the downtown area. However, &lt;a href=&quot;http://www.flightradar24.com/39.66,-86.27/10&quot;&gt;FlightRadar24&lt;/a&gt; for the area doesn't seem to show them at all. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's dim enough that I couldn't make out the markings on the choppers before I went inside, but at least one or two are local news stations, and the third is either another news station or a police chopper. They are in the (normal) flight path of &lt;a href=&quot;http://flightaware.com/live/airport_status_bigmap.rvt?airport=KIND&quot;&gt;Indianapolis International (KIND)&lt;/a&gt; runways 23L and 23R, though I'm sure they're below the approach altitudes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are they not squawking something that would be picked up on either FlightRadar24, &lt;a href=&quot;http://flightaware.com/live/airport_status_bigmap.rvt?airport=KIND&quot;&gt;FlightAware&lt;/a&gt; or similar flight tracking web sites?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt; It does &lt;a href=&quot;http://www.flightradar24.com/SWA429/5ca16e9&quot;&gt;appear&lt;/a&gt; that they're not using RWY 23 this morning, but are using RWY 5L and 5R.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="65" LastEditDate="2015-03-19T13:17:10.580" LastActivityDate="2019-11-15T07:07:03.767" Title="Why do helicopter flights not appear in online flight trackers?" Tags="&lt;online-tracking&gt;&lt;flightradar24&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13336" PostTypeId="2" ParentId="13335" CreationDate="2015-03-19T12:28:32.023" Score="12" Body="&lt;p&gt;FlightRadar and similar websites use &lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot; rel=&quot;noreferrer&quot;&gt;several sources&lt;/a&gt; for aircraft detection, most commonly they use &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;noreferrer&quot;&gt;ADS-B&lt;/a&gt;. Not all General Aviation aircraft, to which helicopters would count normally, are equipped with transponders that are capable of emitting ADS-B data, so they would not show via regular means on FlightRadar.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The primary technology that Flightradar24 use to receive flight information is called automatic dependent surveillance-broadcast (ADS-B).&lt;/p&gt;&#xA;&lt;p&gt;ADS-B is a relatively new technology under development which means that today it's rarely used by Air Traffic Control (ATC). Our estimations show that roughly 65% of all commercial passenger aircraft (75% in Europe, 35% in the US) are equipped with an ADS-B transponder. For general aviation this number is probably below 20%. But this percentage is steadily increasing as ADS-B will become mandatory for most aircraft in most airspaces around the world, by year 2020. When mandatory, ADS-B will replace primary radar as the primary surveillance method used by ATC.&lt;/p&gt;&#xA;&lt;p&gt;Flightradar24 has a network of more than 4,000 ADS-B receivers around the world that receives plane and flight information from aircraft with ADS-B transponders and sends this information to our servers. Due to the high frequency used (1090 MHz) the coverage from each receiver is limited to about 250-400 km (150-250 miles) in all directions depending on location. The farther away from the receiver an aircraft is flying, the higher it must fly to be covered by the receiver. The distance limit makes it very hard to get ADS-B coverage over oceans.&lt;/p&gt;&#xA;&lt;p&gt;About 99% of Europe is covered with ADS-B receivers. There is also good ADS-B coverage in USA, Canada, Mexico, Caribbean, Brazil, Russia, Middle East, India, Japan, Thailand, Malaysia, Indonesia, Australia and New Zealand. In other parts of the world the ADS-B coverage varies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The other option is to receive the regular Mode-S transponder signal by a technique called &lt;a href=&quot;http://en.wikipedia.org/wiki/Multilateration&quot; rel=&quot;noreferrer&quot;&gt;Multilateration (MLAT)&lt;/a&gt;, however the FlightRadar website states that this is something that only works reliably at high altitude, at least 5 000 to 10 000 ft.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In some regions with coverage from several FR24-receivers we also calculate positions of non-ADS-B equipped aircraft with the help of Multilateration (MLAT), by using a method known as Time Difference of Arrival (TDOA). By measuring the difference in time to receive the signal from aircraft with an older ModeS-transponder, it's possible to calculate the position of these aircraft. Four FR24-receivers or more, receiving signals from the same aircraft, are needed to make MLAT work. That means that MLAT coverage can only be achieved above about 5,000-10,000 feet as the probability that signal can be received by four or more receivers increases with increased altitude.&lt;/p&gt;&#xA;&lt;p&gt;Most parts of Europe are today covered with MLAT above about 5,000-10,000 feet. There is also some MLAT coverage in North America, Mexico, Australia and Brazil. More areas will get MLAT coverage during 2014 and 2015.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For more information, check &lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot; rel=&quot;noreferrer&quot;&gt;FlightRadar's &amp;quot;How it works&amp;quot;&lt;/a&gt; page.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-20T06:21:33.693" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13337" PostTypeId="2" ParentId="13331" CreationDate="2015-03-19T15:19:20.280" Score="16" Body="&lt;p&gt;Generally speaking, airliners do not have microwave ovens for safety reasons. I could not find any reference where commercial airplanes used to have microwaves. Probably some smaller business jets have them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some flight attendants &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20080331031137AAjb0Sa&quot; rel=&quot;noreferrer&quot;&gt;mention&lt;/a&gt; that they can warm your food, but some &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20110916211348AA2UC8z&quot; rel=&quot;noreferrer&quot;&gt;say&lt;/a&gt; that they will not for legal and health reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As also &lt;a href=&quot;https://aviation.stackexchange.com/questions/13331/did-commercial-airliners-have-microwave-ovens-in-the-past#comment29281_13331&quot;&gt;mentioned by sweber&lt;/a&gt; in comments to the question, meals are not heated at the airport. Airline catering companies like &lt;a href=&quot;http://en.wikipedia.org/wiki/LSG_Sky_Chefs&quot; rel=&quot;noreferrer&quot;&gt;LSG Sky Chefs&lt;/a&gt; prepare the meal near the airport and deliver it to the airplane. Inside the airplane, they use &lt;a href=&quot;http://en.wikipedia.org/wiki/Convection_oven&quot; rel=&quot;noreferrer&quot;&gt;convection ovens&lt;/a&gt; to heat it.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-03-19T17:28:56.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13338" PostTypeId="2" ParentId="13332" CreationDate="2015-03-19T15:28:37.407" Score="5" Body="&lt;p&gt;If I understand Bernoulli's principle correctly, it's the interaction of solid surfaces with fluids that attach and flow along. In this regard Leonardo's craft would be using Bernoulli's principle. If it were not, the air wouldn't go down but towards the outside or &quot;up&quot; along the blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact first propellers looked quite like that design and were used on boats. They were derived from Archimedes' screws. Experiments showed that less &quot;propeller&quot; created less drag in the water, i.e. running more efficiently. Extrapolating that to the lesser viscosity of air led to even slimmer propeller blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's like the other answers pointed out, alternatives to Bernoulli's principle are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;displacement -&gt; lighter than air&lt;/li&gt;&#xA;&lt;li&gt;impuls -&gt; rockets&lt;/li&gt;&#xA;&lt;li&gt;electromagnetism -&gt; transrapid (although it's altitude is in the order of centimeters)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Arguably there might be some sort of antigravitation possible employing the gyroscopic effect. But I never heard of anyone successfully doing that. However I remember seeing a Youtube video that I can't seem to find again. In it was a physics professor, who spun up a heavy weight on a long stick to 10.000 RPM and then lifting it single handedly at the end of the stick. Didn't seem to be much of an effort as long as he guided the stick into a spiral motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the matter of planes using the Bernoulli principle, aircraft wings do displace air, but as they are heavier than the displaced air this does not create enough lift for an aircraft to fly. I think what @Nick means with &quot;displacing downwards&quot; is the same as what @erich means with &quot;push the air below it down&quot;. The actio=reactio in this is termed impulse in physics. Yes, this also contributes some lift but is also neglectible as there isn't much (mass of) air pushed down. You can see that in wind channel tests of wing profiles or when aircrafts fly through smoke. The overwhelming majority of lift is in fact generated by the difference in pressure between the upper and lower side of the wing. This pressure difference is due to Bernoulli's principle. An aircraft flying inverted adjusts its angle of attack to compensate for the mismatch in wing profile. Actually only aircrafts designed to fly inverted can safely do so. Aerobatics have almost neutral wing shapes that create lift only according to angle of attack plus they have lots of excess power to generate lift from. For more on negative lift, angle of attack and flying inverted see the answer to this : &lt;a href=&quot;https://aviation.stackexchange.com/questions/1152/if-the-profile-of-a-wing-pulls-a-plane-up-why-can-planes-fly-inverted&quot;&gt;If the profile of a wing pulls a plane up, why can planes fly inverted?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7695" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-19T16:48:25.803" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13339" PostTypeId="2" ParentId="13332" CreationDate="2015-03-19T15:33:14.570" Score="8" Body="&lt;p&gt;Airplanes :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.allstar.fiu.edu/aero/airflylvl3.htm&quot;&gt;http://www.allstar.fiu.edu/aero/airflylvl3.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although Bernoulli's principle is part of the reason why airplane wings generate lift, they also rely on displacing air downwards, in a similar way that the giant augur would, or in a similar way that a sail can convert a crosswind into forward momentum.&lt;/p&gt;&#xA;" OwnerUserId="7696" LastActivityDate="2015-03-19T15:33:14.570" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13340" PostTypeId="1" CreationDate="2015-03-19T19:54:12.470" Score="11" ViewCount="1237" Body="&lt;p&gt;I was going over &lt;a href=&quot;http://en.wikipedia.org/wiki/Special_visual_flight_rules&quot;&gt;Special Visual Flight Rules (SVFR)&lt;/a&gt; with my instructor recently and he told me that he has only requested it a few times, and that it is mainly used if you are flying from deteriorating weather into improving weather. In other words, you are sure that where you are going is clear. I got thinking about it and felt that if there were ever an SVFR situation, I would most likely ground the flight (until I get my instrument rating that is).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, how often do pilots request SVFR?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like it would cause people to end up in situations that they can't handle i.e. weather deteriorates more instead of getting better, does this happen often?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;It has been mentioned that SVFR rules vary from country to country, I am asking about peoples experiences in the USA but am happy to hear of other similar situations around the world as well.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-03-20T12:54:06.670" LastActivityDate="2016-07-05T06:45:48.333" Title="How often do people fly SVFR?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;visual-flight-rules&gt;&lt;special-vfr&gt;" AnswerCount="5" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13341" PostTypeId="2" ParentId="13340" CreationDate="2015-03-19T20:38:13.723" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The below was posted before the OP clarified in his question that he was interested in FAA-based data and anwers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not aware of any statistical data, but I can answer the second question in your text.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that SVFR is not only about visibility, but also about staying clear of clouds. Airspace D in Germany requires cloud distances of 1.000ft vertically and 1.5km horizontally. You are also required to remain at least 500ft above ground during flight, except for landings and takeoff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your cloud base drops below 1.500ft, you could technically no longer maintain VMC, even though maybe your visibility was more than 10km. In this case your only option is to request SVFR.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T13:00:19.180" LastActivityDate="2015-03-20T13:00:19.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13342" PostTypeId="2" ParentId="13340" CreationDate="2015-03-19T20:38:28.017" Score="8" Body="&lt;p&gt;From my experience in the US at the facilities I've worked, and the discussions I've had with other controllers, it depends heavily on the area's weather patterns. The facilities I've worked, it's been usually a tool, when people are trying to get in right before the weather hits, or they're seeing good improvement in neighboring airports and at the main one, and know that it'll be good enough to make it between the two areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other places, like coastal or areas where fog banks are common, SVFR can be useful, esp if only half the field is covered in clouds, and you need to make it in or can easily get out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I'd probably just file IFR and cancel when I got to a good spot VFR, if I just wanted to go out and enjoy, versus just flying to a destination. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, note, SVFR in terms of separation is only one SVFR aircraft(and really aircraft period) in the airspace at a time. So, you'll be delayed to come in if there's IFR, or other SVFR aircraft ahead of you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters generally do request it more than fixed wing aircraft in my experience. Also, realize a pilot has to explicitly request SVFR, a controller can't prompt or hint at the correct terminology to use to request like saying &quot;Do you have a SPECIAL request&quot;&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="6" LastEditDate="2015-03-26T02:56:28.123" LastActivityDate="2015-03-26T02:56:28.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13343" PostTypeId="2" ParentId="13340" CreationDate="2015-03-19T20:55:51.193" Score="4" Body="&lt;p&gt;I've done it once, or maybe twice in 1200 hours of flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first time was when I was stuck at an airport in the LA basin which was below standard VFR minimums due to how thick the smog was. I filed SVFR to take off, and by 5000 feet I was above the smog layer and it was blue skies the rest of the way home.&lt;/p&gt;&#xA;" OwnerUserId="87" LastActivityDate="2015-03-19T20:55:51.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13344" PostTypeId="1" AcceptedAnswerId="13348" CreationDate="2015-03-19T21:16:18.120" Score="11" ViewCount="1475" Body="&lt;p&gt;If my IFR rating is not current, does this mean I &lt;strong&gt;can't fly by IFR&lt;/strong&gt;, or does it just mean that I &lt;strong&gt;can't fly in IMC&lt;/strong&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that if it's just the latter, then it would make sense to fly IFR if the weather is still VMC. It would allow me to stay current on procedures while waiting for the opportunity to get my rating current.&lt;/p&gt;&#xA;" OwnerUserId="87" LastEditorUserId="87" LastEditDate="2015-03-20T19:05:04.483" LastActivityDate="2019-10-03T01:07:22.923" Title="Can I fly IFR in VMC if my instrument rating is not current?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;currency&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13345" PostTypeId="1" AcceptedAnswerId="13365" CreationDate="2015-03-19T21:45:10.320" Score="12" ViewCount="271" Body="&lt;p&gt;As a US licensed and trained pilot, I know I can fly into Canada, but are there are airspace rules that are different from the American system. Is there a Canadian rules test or conversion you can or should do, or should I just expect to fly in Canada by the exact same rules and procedures as in the United States?&lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="62" LastEditDate="2015-03-20T14:42:07.093" LastActivityDate="2018-06-29T14:19:30.117" Title="How can I become familiar with flight rules specific to Canada when flying there from the United States?" Tags="&lt;international&gt;&lt;canada&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13346" PostTypeId="2" ParentId="13332" CreationDate="2015-03-19T21:57:06.470" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;…giant auger. This design would not have exploited Bernoulli's Principle…&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wings and propellers generate lift by exactly the same principle. The auger would work just like the slender rotating wings of a modern helicopter, just less efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, anything that flies flies because it generates some force that balances gravity. It can generate the force by using buoyancy or accelerating reaction mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Buoyancy is what balloons and airships use. It has great advantage that it does not need any energy. It has disadvantage that it needs huge structure, because air has very low density and thus provides only very little buoyancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other option, moving reaction mass, can be again done in two ways: by expelling material carried for the purpose or by accelerating the surrounding air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Expelling material carried for the purpose is what rockets do. It is the only currently working way to accelerate in space where outside reaction mass is not available, but for aircraft it is extremely impractical, because a lot of reaction mass is needed and lifting it needs more reaction mass and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what remains is accelerating surrounding air. And this always boils down to moving a slanted surface through it that always accelerates it using the same principle. Linearly moving wing, rotating wing/propeller, turbine or augur are all slanted surfaces moving through air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important properties of air here are viscosity and inertia. Due to viscosity the flow tends to remain attached to the wing and due to inertia it continues downwards after flowing off the downward-slanted trailing edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you can use the simple argument of action and reaction—the air is accelerated downward, so the wing must apply force to it and therefore the air applies reaction force of the same magnitude and opposite direction to the wing, the lift—or you can use viscosity, inertia, conservation of mass and conservation of energy (that is Bernoulli's principle) to calculate how the pressure field around the wing looks and notice the lower pressure above the wing then under it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither explanation is more correct than the other; laws of nature all hold at the same time and there are multiple ways to calculate most things. However, Bernoulli's principle is not itself sufficient to explain lift. It is only one of several important properties of fluids that together explain it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-03-19T21:57:06.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13347" PostTypeId="1" CreationDate="2015-03-19T22:47:38.947" Score="12" ViewCount="778" Body="&lt;p&gt;There are a few aircraft, such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Britten-Norman_Trislander&quot;&gt;Britten-Norman Trislander&lt;/a&gt;, that use three piston engines -- one on each wing and one mounted along the centerline somewhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is fine and good, but how do you tell in a timely fashion that the #2 (centerline) engine has quit?  The engine gauges are in no hurry to tell you, as per &lt;a href=&quot;http://www.enginehistory.org/wbn/WBN06.pdf&quot;&gt;Randy Sohn's Warbird Notes #6&lt;/a&gt;, and there's no adverse yaw because it's a centerline-mounted engine, but you still need to know and quick because unless you can get that prop feathered, there's a giant drag bucket hanging off your vertical tail!&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3504" LastEditDate="2015-03-22T22:25:28.193" LastActivityDate="2015-03-22T22:25:28.193" Title="How can the pilot tell the center engine failed on a piston aircraft with three engines?" Tags="&lt;piston-engine&gt;&lt;engine-failure&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13348" PostTypeId="2" ParentId="13344" CreationDate="2015-03-19T23:23:12.920" Score="16" Body="&lt;p&gt;No, you cannot. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot;&gt;14 CFR 61.57 (c)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Instrument experience. Except as provided in paragraph (e) of this section, a person may act as pilot in command under IFR or weather conditions less than the minimums prescribed for VFR only if: [instrument currency requirements]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To accept an IFR clearance as PIC, even in VMC, you must be instrument current. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="65" LastEditDate="2015-03-20T13:11:34.587" LastActivityDate="2015-03-20T13:11:34.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13349" PostTypeId="2" ParentId="13347" CreationDate="2015-03-19T23:27:44.217" Score="10" Body="&lt;p&gt;If the engine quits you will lose some thrust which will affect the plane's handling. You may even begin to descend slowly which the pilot will notice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most importantly you have engine instruments which will tell you, quite quickly, the engine has quit. If you have one, your manifold pressure will drop since you are no longer producing power, or your tach will reflect what is happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all that fails you I would think there would be an audible difference if the engine cut out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the cockpit of the aircraft in question:&#xA;&lt;a href=&quot;http://www.jetphotos.net/viewphoto.php?id=6120398&quot; rel=&quot;nofollow noreferrer&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/pwTbM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: Jetphotos.net)&lt;/sup&gt;&#xA;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does show independent MAP and RPM gauges for each engine as opposed to some planes that have a single gauge with multiple hands (one for each engine). You would surely be able to see an altered reading on one of these gauges. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="938" LastEditDate="2015-03-22T22:05:27.173" LastActivityDate="2015-03-22T22:05:27.173" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13350" PostTypeId="1" AcceptedAnswerId="13366" CreationDate="2015-03-19T23:56:46.080" Score="11" ViewCount="5041" Body="&lt;p&gt;I watched some videos on YouTube where the pilot used the thrust-reverser for push-back instead of the push-back tug. Some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=-Zkxh903s_w&quot;&gt;MD80 Powerback&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=mO-FdDKxuNU&quot;&gt;DC9 Ground Reverser Powerback&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this procedure currently in use? Would an airline today certify a 737, or even turboprop, like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Beechcraft_1900#1900D&quot;&gt;Beechcraft 1900D&lt;/a&gt;, to execute such a maneuver?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also seen a Boeing 727 video. 727s and MD80s have the engines attached directly to the fuselage, not in the wings. Would that be one of the reasons? &lt;/p&gt;&#xA;" OwnerUserId="74" LastEditorUserId="1467" LastEditDate="2015-03-21T09:47:27.243" LastActivityDate="2018-02-04T14:25:30.543" Title="Is a powerback allowed by airlines as a safe maneuver?" Tags="&lt;thrust-reverser&gt;&lt;powerback&gt;&lt;pushback&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13351" PostTypeId="2" ParentId="13350" CreationDate="2015-03-20T00:23:17.173" Score="1" Body="&lt;p&gt;A plane can powerback if you can configure the engines to provide more backwards thrust than forward thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fixed pitch propellers can't provide any reverse thrust. With variable pitch props it depends on whether the there is enough pitch control to reverse it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However powerback has the risk of debris getting into the engine. The air will blast forwards and possible damage the gate so it's not used there. That and the guys on the ground don't appreciate getting blasted.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-03-20T00:23:17.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13352" PostTypeId="2" ParentId="13350" CreationDate="2015-03-20T00:42:53.603" Score="1" Body="&lt;p&gt;I've got a few hours in the 1900 and a couple hundred in the smaller KingAir. I &lt;em&gt;think&lt;/em&gt; you can reverse the props while sitting still and push back with the negative thrust. But you probably shouldn't. You'd probably be safer doing it in the Beech than a 737, since the intakes on the Beech are significantly smaller (and have the prop directly in front of them pushing the air/debris outward). The 737 engine doesn't change the direction that it's sucking the air in. Just how it's blowing it out. I'd still think it would be a FOD nightmare. &lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2015-03-20T00:42:53.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13353" PostTypeId="2" ParentId="13350" CreationDate="2015-03-20T04:05:32.907" Score="5" Body="&lt;p&gt;Any aircraft with thrust reversers or reversible props should in theory be able to execute a powered pushback, FOD and ground facilities damage notwithstanding.  In a previous life I was an AC-130 crew chief -- loved the fact that those things could back up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I think the main reason you don't see many air carriers using their thrust reversers for pushback is because of the hazard to everything outside the aircraft -- people, baggage carts, fuel trucks, jetway bits, and the terminal windows.  I can't find a reference for it at the moment, but I do remember one US airport banning powerbacks in the late 70's or early 80's after a gate area window was shattered.  My recollection is that powerbacks fell out of favor and we started seeing tugs used everywhere around that time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a good &lt;a href=&quot;http://asrs.arc.nasa.gov/publications/directline/dl6_blast.htm&quot; rel=&quot;noreferrer&quot;&gt;ASRS article&lt;/a&gt; about not only powerbacks but blast damage incidents in general.&lt;/p&gt;&#xA;" OwnerUserId="7700" LastEditorUserId="65" LastEditDate="2015-03-20T16:28:48.277" LastActivityDate="2015-03-20T16:28:48.277" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13354" PostTypeId="2" ParentId="13350" CreationDate="2015-03-20T05:51:44.803" Score="1" Body="&lt;p&gt;Both power back and taxiing under thrust are on their way out. Efficiency is horrible, so electrically powered wheels are planned for the next step in fuel efficiency improvement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not to be misunderstood: Currently this is not yet being used on production aircraft. But it looks likely to come.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-03-20T05:51:44.803" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13355" PostTypeId="5" CreationDate="2015-03-20T07:03:34.123" Score="0" Body="" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T07:03:34.123" LastActivityDate="2015-03-20T07:03:34.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13356" PostTypeId="4" CreationDate="2015-03-20T07:03:34.123" Score="0" Body="Special Visual Flight Rules allow VFR flights to enter or leave a controlled airspace, in most jurisdictions limited to control zones, if Visual Metrological Conditions cannot be met in the controlled airspace, but would otherwise be met in the surrounding airspace." OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T08:39:53.840" LastActivityDate="2015-03-20T08:39:53.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13357" PostTypeId="1" AcceptedAnswerId="13358" CreationDate="2015-03-20T07:40:42.530" Score="3" ViewCount="2632" Body="&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/questions/13315/recycling-air-cabin-and-isolating-a-toillet&quot;&gt;question&lt;/a&gt;, led me to wonder, how big are the tanks that hold poo. I had seen a BBC video, showing how they empty the tank on an A380 at Heathrow, can't remember the capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what about planes like Cessna etc, do they have toilets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an emergency can the tank be emptied, in case it overweight, i.e. above the &lt;a href=&quot;http://en.wikipedia.org/wiki/Maximum_landing_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;Maximum Landing Weight&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-20T12:46:09.980" Title="What is the size of toilet or septic tanks in various planes?" Tags="&lt;cabin-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13358" PostTypeId="2" ParentId="13357" CreationDate="2015-03-20T08:28:22.070" Score="4" Body="&lt;p&gt;The A380 has a total waste tank capacity of &lt;code&gt;2096L&lt;/code&gt; or &lt;code&gt;554 US gal&lt;/code&gt;, &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-20131201.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;according to Airbus&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;B. Capacity&#xA;  There are four waste tanks, two upper deck tanks and two main deck tanks, see FIGURE&#xA;  5-4-10-991-003-A.&lt;br&gt;&#xA;  (1) Upper Deck Waste-Tanks&#xA;  - 373 l (99 US gal).&#xA;  &lt;br&gt;Each tank is precharged with 35 l (9 US gal) of chemical fluid.&#xA;  &lt;br&gt;(2) Main Deck Waste-Tanks&#xA;  - 675 l (178 US gal).&#xA;  Each tank is precharged with 35 l (9 US gal) of chemical fluid.&#xA;  &lt;br&gt;(3) Total Waste Tank Capacity&#xA;  - 2096 l (554 US gal).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The size will vary for each aircraft type, the &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/334387/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747 had a capacity of only &lt;code&gt;1000L&lt;/code&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller General Aviation aircraft do not have lavatories, this depends on aircraft size and purpose. The average Cessna will not have lavatories either, pilots have to plan their stops properly or rely on accessory such as the TravelJohn. Larger General Aviation aircraft such as smaller jets and aircraft designed for more than 4 passengers are more likely to have lavatories on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/x9WLL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.siebert.aero/products/Katalog/Pilotenausrstung/Cockpitzubehr/Noturinal-Spucktten/Noturinal-Travel-John.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Siebert Aero&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no dumping system for waste tanks, mostly for hygienic and environmental reasons, as the waste tanks are not only filled with fecal and thus biological matter, but also with chemicals.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T08:35:16.223" LastActivityDate="2015-03-20T08:35:16.223" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13359" PostTypeId="2" ParentId="13347" CreationDate="2015-03-20T10:47:43.837" Score="6" Body="&lt;p&gt;Without having flown this particular aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Wikipedia, the aircraft is powered by the, non-turbocharged, Lycoming O-540-E4C5. This means that in a climb for instance, where you'd likely be at full throttle with this engine, if an engine stops (seizes), its indicated Manifold Pressure (MP) will be near ambient pressure, just like the other, running engines will be (at least for practical purposes), if it windmills, the engine will still work as a vacuum pump out of the throttle manifold, maintaining a still reasonable MP-setting. As the propeller will be windmilling initially, RPM is likely to, at least initially, stay in the same ballpark as the other engines (anyone who's flown older light piston aircraft will tell you most engine instruments are not accurate enough to make exact comparisons by value between the engines, try for instance syncing the propellers by the RPM gauge, and not by your ears). Unless the aircraft is equipped with torque indicators (not likely), the first instrument you will clearly be able to identify the engine failure is likely going to be the Exhaust Gas Temperature (EGT, an instrument I'm not sure if this aircraft is equipped with).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a climb, or high powered cruise, the aerodynamic/kinesthetic feedback of the aircraft will be significant enough if you lose 1 of 3 engines, (deceleration, loss of climb performance, torque, change in sound) to warrant further investigation (and with proper training/experience, rather quickly conclude an engine failure). In a low powered descent, an engine failure can be quite insidious even on a light twin, and you are actually not likely to detect it until you apply power to level out.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-03-20T14:28:32.353" LastActivityDate="2015-03-20T14:28:32.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13360" PostTypeId="2" ParentId="2890" CreationDate="2015-03-20T11:25:59.460" Score="-4" Body="&lt;p&gt;Aircraft is flying in the air by 1 G force that resist the gravity of earth and keep the aircraft stay airborne. So if we lose this lifting force that is generated by the differential pressure between the upper and lower side of the wings, in this case the weight force, it will overcomes the lift and will pull that weight of aircraft to the downward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the zero G means the weight will be a little bit more than of lift, And eventually the zero G will account as weightlessness but it will be moving toward the centre of gravity (the earth). Why? because we are still flying at the atmosphere environments.&lt;/p&gt;&#xA;" OwnerUserId="7704" LastEditorUserId="65" LastEditDate="2015-03-20T13:49:30.747" LastActivityDate="2015-03-20T13:49:30.747" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13361" PostTypeId="1" CreationDate="2015-03-20T12:04:26.187" Score="2" ViewCount="91" Body="&lt;p&gt;Sometimes I wonder why the manufacturers do not design a big parachute to carry the aeroplanes when serious accidents occur. Perhaps the high cost is the reason?! But is it more expensive than a human life!?&lt;/p&gt;&#xA;" OwnerUserId="7704" LastEditorUserId="572" LastEditDate="2015-03-20T12:19:00.340" LastActivityDate="2015-03-20T12:19:00.340" Title="Why are there no parachutes to carry the aeroplanes in case of serious accidents?" Tags="&lt;emergency&gt;&lt;parachute&gt;&lt;emergency-services&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-03-20T12:47:05.453" ContentLicense="CC BY-SA 3.0" />
  <row Id="13363" PostTypeId="5" CreationDate="2015-03-20T14:02:51.020" Score="0" Body="&lt;p&gt;For more information see &lt;a href=&quot;http://en.wikipedia.org/wiki/G-force&quot; rel=&quot;nofollow&quot;&gt;g-force&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T14:02:51.020" LastActivityDate="2015-03-20T14:02:51.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13364" PostTypeId="4" CreationDate="2015-03-20T14:02:51.020" Score="0" Body="g-force (with g from gravitational) is a measurement of the type of acceleration that indirectly causes weight. Despite the name, it is incorrect to consider g-force a force, as &quot;g-force&quot; (lower case character) is a type of acceleration that can be measured with an accelerometer." OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-20T14:02:51.020" LastActivityDate="2015-03-20T14:02:51.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13365" PostTypeId="2" ParentId="13345" CreationDate="2015-03-20T14:41:21.847" Score="6" Body="&lt;p&gt;In the specific case of Canada, AOPA and COPA have a lot of information aimed at US pilots. AOPA has a &lt;a href=&quot;http://www.aopa.org/Flight-Planning/Canada&quot; rel=&quot;nofollow noreferrer&quot;&gt;complete guide&lt;/a&gt; on documents, customs etc. and COPA has &lt;a href=&quot;https://copanational.org/en/flyingtocanada/&quot; rel=&quot;nofollow noreferrer&quot;&gt;a page&lt;/a&gt; with more information, which includes this remark:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The flying rules are almost indistinguishable - reading the COPA guide&#xA;  should keep you legal and out of trouble. Make sure you get a Canada&#xA;  Flight Supplement (CFS) and some VNCs (Canadian equivalent to your US&#xA;  sectionals), that will allow you to navigate VFR safely.   IFR plates&#xA;  are available from Nav Canada as a subscription or the (sample list&#xA;  of) vendors included below. (by mail order)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The guide is free but available to AOPA/COPA members only.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-02-27T15:35:36.417" LastActivityDate="2018-02-27T15:35:36.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13366" PostTypeId="2" ParentId="13350" CreationDate="2015-03-20T16:11:59.547" Score="16" Body="&lt;p&gt;Most modern commercial airliners are prohibited to power back.&#xA;Ground operations in aircraft fitted with high-bypass engines are usually restricted to idle and low-idle operations (enough to make the craft start moving, after which momentum enables further movement with idle only). &#xA;Aircraft capable of power back are predominantly thus turboprops, several operators of these allow their crews to operate accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not in common use anymore, for the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thrust reversing can kick up a lot of debris, posing a safety hazard. This would generally preclude any ground crew or spotters walking under the jet as is often done during pushbacks.&lt;/li&gt;&#xA;&lt;li&gt;The previous point's especially true for under-wing jet engine designs, so only jets with fuselage-mounted engines are allowed to do it, and most of the bigger designs (DC-9, MD-80, 727) are being phased out of most fleets.&lt;/li&gt;&#xA;&lt;li&gt;Pilots in most craft can't see behind them, another possible safety hazard requiring multiple spotters to be in contact with the pilot.&lt;/li&gt;&#xA;&lt;li&gt;Thrust reversing uses a lot of fuel, so it's usually cheaper for the airlines to use a guy on a tractor for an assisted pushback.&lt;/li&gt;&#xA;&lt;li&gt;Thrust reversing is loud, and during a powerback that noise is in close proximity to the terminal. The tarmac's a noisy place, but usually not &lt;em&gt;that&lt;/em&gt; loud.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you want to see a powerback performed by a commercial airliner, fly out to L'Esperance in St. Martin. The runway there is very short and has no taxiway leading to the end of the runway from either end, so larger passenger turboprops that service that airport have to turn onto the runway about 2/3 down its length, face their desired takeoff direction, then powerback to the end of the runway in order to have enough to take off. The larger and (relatively) busier Princess Juliana International, on the Netherlands side, has taxiways and turnaround areas at both ends of its runway.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7532" LastEditDate="2018-02-04T14:25:30.543" LastActivityDate="2018-02-04T14:25:30.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13367" PostTypeId="2" ParentId="13326" CreationDate="2015-03-20T17:29:20.173" Score="2" Body="&lt;p&gt;I pitch in blind here, but I believe in some instances fuel is circulated for heat exchange.&lt;/p&gt;&#xA;" OwnerUserId="7708" LastActivityDate="2015-03-20T17:29:20.173" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13368" PostTypeId="2" ParentId="572" CreationDate="2015-03-20T19:13:41.957" Score="0" Body="&lt;p&gt;I have never experienced engine problems on descent, but I have experienced 2 engine failures shortly after take-off. One cylinder head crack about 5 minutes after take-off(C-150) and one stuck valve(C-172) less than a minute after take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot be sure the exact cause, but I suspect the rapid heating of the engine had the same negative effect, but in reverse order, of shock cooling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I make sure the engine is warm (via what ever is available...) before take off.  The checklist may say &quot;eng temp in the green&quot;, but why not let it climb up toward the middle of the green a little further to allow the engine to expand a little more before adding full power on take-off? The engine still has some heating and expanding to do while at idle, and is about to heat rapidly once take-off power is applied.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe the majority of the engine stress/damage happens at take-off, not on descent. &lt;/p&gt;&#xA;" OwnerUserId="7709" LastEditorUserId="3201" LastEditDate="2015-03-20T20:44:42.517" LastActivityDate="2015-03-20T20:44:42.517" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13369" PostTypeId="1" AcceptedAnswerId="13372" CreationDate="2015-03-20T19:17:02.100" Score="4" ViewCount="3991" Body="&lt;p&gt;I've been looking at Canadian VNCs (VFR Navigation Charts) and they look surprisingly different from US sectionals. A big difference seems to be how the airspace is designed, but there seem to be a lot of other differences in how information is displayed. For example, here is the Denver class B airspace:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EBZ7f.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EBZ7f.jpg&quot; alt=&quot;FAA VFR Sectional - Denver Airspace&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have your basic upside down wedding cake, and a mode C veil. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now here is the Calgary, Canada class B airspace:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NeZ0b.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NeZ0b.jpg&quot; alt=&quot;Calgary class B airspace&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though it's not a full picture of the airspace, there are some differences that jump out, like the choice of colors to indicate the airspace boundaries and elevation, and the fact that the airspace is HUGE! There is also no clear indication of a mode C veil, or the bottom/top of the airspace. Another thing I've noticed is the huge number of airspace boundaries, indicated by the lines that looks something like this: &lt;code&gt;-_-_-_-_&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One more thing. There is no information about the Calgary or Springbank airports. Are airspace elevations, airport elevation, and frequencies all things you have to look up separately?&lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="4509" LastEditDate="2015-03-20T20:03:39.000" LastActivityDate="2019-01-05T20:47:51.203" Title="What are the differences between Canadian VNCs and US Sectional charts?" Tags="&lt;visual-flight-rules&gt;&lt;aeronautical-charts&gt;&lt;canada&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13370" PostTypeId="5" CreationDate="2015-03-20T20:29:06.233" Score="0" Body="" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-03-20T20:29:06.233" LastActivityDate="2015-03-20T20:29:06.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13371" PostTypeId="4" CreationDate="2015-03-20T20:29:06.233" Score="0" Body="A belly landing occurs when an aircraft lands without its landing gear fully extended and uses its underside, or belly, as its primary landing device." OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-03-20T20:29:06.233" LastActivityDate="2015-03-20T20:29:06.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13372" PostTypeId="2" ParentId="13369" CreationDate="2015-03-21T04:56:29.463" Score="2" Body="&lt;p&gt;The short answer is the charts are different because they're made by different groups - NAV CANADA has different charting standards than the FAA/NACO uses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly Jeppesen makes VFR charts for the United States, and they look very different from a FAA/NACO chart:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/G141Q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G141Q.jpg&quot; alt=&quot;Jeppesen vs NACO chart&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;sub&gt;I have charitably described the Jeppesen VFR+GPS charts as &quot;technicolor puppy vomit&quot; on more than one occasion.&lt;/sub&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as I'm aware there's no comprehensive listing of &lt;em&gt;all&lt;/em&gt; the differences between the US VFR Sectional format and the Canadian VNC format, but the NavCanada charts have a legend and there &lt;a href=&quot;http://www.navcanada.ca/EN/products-and-services/Pages/aeronautical-information-products-canada-flight-supplement.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Canada Flight Supplement (CFS)&lt;/a&gt; contains a great deal of additional information - it's essentially similar to the US Airport/Facility directory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike the US charts, &lt;a href=&quot;http://www.navcanada.ca/EN/products-and-services/pages/aeronautical-information-products-charts.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Canadian Aeronautical Charts&lt;/a&gt;--including the VNC--do not have a specific expiration date. They are revised periodically.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="287" LastEditDate="2018-08-14T13:25:05.213" LastActivityDate="2018-08-14T13:25:05.213" CommentCount="2" CommunityOwnedDate="2015-03-21T04:56:29.463" ContentLicense="CC BY-SA 4.0" />
  <row Id="13373" PostTypeId="1" CreationDate="2015-03-21T07:52:33.523" Score="1" ViewCount="637" Body="&lt;p&gt;Statistics about plane accidents consistently show pilot (or other human) error as the leading cause of crashes. With current advances in technology, it is therefore tempting to strive towards replacement of pilots with automated systems. However, I have never seen a tally of how many plane crashes are actually prevented by pilot skill, that would otherwise have resulted in loss of life. Are there any statistics available on this subject?&lt;/p&gt;&#xA;" OwnerUserId="7716" LastEditorUserId="65" LastEditDate="2015-03-21T12:04:57.743" LastActivityDate="2015-03-21T12:04:57.743" Title="How many plane crashes are prevented by pilots?" Tags="&lt;airliner&gt;&lt;accidents&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ClosedDate="2015-03-21T13:16:35.993" ContentLicense="CC BY-SA 3.0" />
  <row Id="13374" PostTypeId="2" ParentId="13373" CreationDate="2015-03-21T08:17:11.247" Score="6" Body="&lt;p&gt;Any manually-flown landing would meet your requirements. If the pilot does nothing on final approach, the plane will almost certainly come to a fiery end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landings that were very, very close to a crash aren't reported all that often - if you made some monumental screwup and managed to salvage it, would you write it up for the FAA? Not many people report almost-car-accidents or red light violations either.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-03-21T08:17:11.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13375" PostTypeId="1" AcceptedAnswerId="13376" CreationDate="2015-03-21T09:30:57.743" Score="11" ViewCount="2738" Body="&lt;p&gt;I've often as a passenger noticed the difference of the sound coming from different airliners. I believe the two manufacturers I have compared are Rolls-Royce and GE, where the latter's engines sound more &quot;electric&quot; (funny enough) and the former's more distorted and noisy.&#xA;Do these observations make sense? And what could possibly create such a difference i sound? I was in the belief that engine design of turbofan engines is somewhat established and detailed.&lt;/p&gt;&#xA;" OwnerUserId="1344" LastEditorUserId="167" LastEditDate="2015-03-21T20:41:33.353" LastActivityDate="2015-03-21T20:41:33.353" Title="What could cause GE and Rolls-Royce turbofan engines to sound different?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13376" PostTypeId="2" ParentId="13375" CreationDate="2015-03-21T09:50:57.573" Score="13" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot;&gt;GE90 engines&lt;/a&gt; have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Bypass_ratio&quot;&gt;higher bypass ratio&lt;/a&gt; than the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot;&gt;RR Trent&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The majority of engine noise, especially the &quot;ripping, howling, typical jet noise&quot; comes from the engine core.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher the bypass ratio, the less air passing through the core for any given thrust and the more cold air meets the core exhaust at the back reducing the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_noise&quot;&gt;shear&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines with no bypass ratio and deep intakes produce a &lt;a href=&quot;https://www.youtube.com/watch?v=H_ARSE8jEHQ&quot;&gt;wonderful sound&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-03-21T10:00:59.767" LastActivityDate="2015-03-21T10:00:59.767" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13377" PostTypeId="1" AcceptedAnswerId="13378" CreationDate="2015-03-21T09:51:34.043" Score="21" ViewCount="1974" Body="&lt;p&gt;A partial or total eclipse is as dark as twilight, but only for a short period. Does it count as night flying for regulatory purposes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for a UK answer, but information about the US is interesting too.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="14897" LastEditDate="2017-07-31T13:59:41.803" LastActivityDate="2017-07-31T13:59:41.803" Title="Is an eclipse considered 'night' for regulatory purposes?" Tags="&lt;caa-uk-regulations&gt;&lt;night-flying&gt;&lt;eclipse&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13378" PostTypeId="2" ParentId="13377" CreationDate="2015-03-21T10:12:20.737" Score="20" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;: that does not count as night flying.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.legislation.gov.uk/uksi/2000/1562/article/129/made&quot; rel=&quot;noreferrer&quot;&gt;CAA defines &amp;quot;Night&amp;quot;&lt;/a&gt; (Air Navigation Order, Article 129) as:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;‘Night’ means the time from half an hour &lt;strong&gt;after sunset&lt;/strong&gt; until half an hour &lt;strong&gt;before sunrise&lt;/strong&gt; (both times inclusive), sunset and sunrise being determined at surface level;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Similarly, the FAA's definition (FAR 1.1) is:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The time between the end of &lt;strong&gt;evening&lt;/strong&gt; civil twilight and the beginning of &lt;strong&gt;morning&lt;/strong&gt; civil twilight, as published in the American Air Almanac, converted to local time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Since an eclipse is neither a sunset or sunrise, nor does it happen between evenings and mornings, it does not fit the definition of &amp;quot;Night&amp;quot; for legal purposes.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-21T10:12:20.737" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13381" PostTypeId="2" ParentId="13375" CreationDate="2015-03-21T16:51:38.483" Score="3" Body="&lt;p&gt;&lt;strong&gt;Intake resonance&lt;/strong&gt; - particularly evident on the Avro Vulcan.  It is a sound that speakers can do no justice to.&lt;/p&gt;&#xA;" OwnerUserId="7708" LastActivityDate="2015-03-21T16:51:38.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13382" PostTypeId="1" AcceptedAnswerId="14079" CreationDate="2015-03-21T19:35:08.337" Score="19" ViewCount="2548" Body="&lt;p&gt;NASA has detailed experiments with a new type of parallel array of small electric propellers on the leading edge of the wing technology that they are calling LEAPTech. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/Features/leaptech.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;press release&lt;/a&gt; notes that the benefits include: &quot;Each motor can be operated independently at different speeds for optimized performance. Key potential benefits of LEAPTech include decreased reliance on fossil fuels, improved aircraft performance and ride quality, and aircraft noise reduction.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;Popular Science&lt;/em&gt; &lt;a href=&quot;http://www.popsci.com/nasa-testing-18-engine-wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; notes that: &quot;When complete, LEAPTech’s planned cruising speed will be 200 miles per hour, with a range of 230 miles on electric power and 460 miles when running as a hybrid. The tremendous and immediate lift generated by this octodecaprop plane and its mere 31-foot wingspan means it should be able to take off from runways as short as 2,000 feet, which is a good 700 feet shorter than the FAA recommends for small passenger aircraft.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is  this related to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9548/what-are-the-advantages-of-a-spinning-wing-magnus-effect-and-why-havent-any-b&quot;&gt;spinning wing (Magnus effect)&lt;/a&gt; or do the benefits accrue from some other aerodynamic effect? This appears to be a technology that would only benefit very small aircraft and would not be scalable, is this correct?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3BCpX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;[Photo credit: NASA]&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2020-01-17T21:25:48.090" Title="What are the advantages of the NASA LEAPTech propeller on wing technology?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;electric-engine&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13384" PostTypeId="2" ParentId="13382" CreationDate="2015-03-21T22:13:42.063" Score="11" Body="&lt;p&gt;The main advantage would be similar to that of &lt;a href=&quot;http://en.wikipedia.org/wiki/Blown_flap&quot; rel=&quot;nofollow noreferrer&quot;&gt;blown flaps&lt;/a&gt;. The flow around the wing will be slightly accelerated, so it operates at a higher effective dynamic pressure. This helps to prevent &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; and allows to create more lift from the same wing area. This effect should be especially noticeable at low speed, when the relative speed increase in the prop wash is highest. However, for the highest effect the propellers will run at maximum power, so the minimum flight speed will only be possible in a climb and approach and landing will require a significantly higher speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other advantages are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;redundancy&lt;/li&gt;&#xA;&lt;li&gt;yaw control by selective power changes&lt;/li&gt;&#xA;&lt;li&gt;Better field of view for pilot and passengers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, once your batteries run empty, the plane should still be flyable to make an emergency landing, and for FAR part 23 certification, the minimum speed &lt;a href=&quot;http://www.flightsimaviation.com/data/FARS/part_23-49.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;should not exceed 61 knots&lt;/a&gt;, especially not in this case. Therefore, the small wing chord of the pictured airplane looks awfully optimistic to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scaling this will not be hard in principle, but the bigger airplanes become, the harder it is to pack enough battery capacity. Bigger airplanes have higher wing loadings and fly faster, so their specific power needs are higher. For the next decades, electric propulsion will foreseeably not be scalable to transport aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-01-17T21:25:48.090" LastActivityDate="2020-01-17T21:25:48.090" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="13385" PostTypeId="1" AcceptedAnswerId="13388" CreationDate="2015-03-22T03:36:56.437" Score="18" ViewCount="5225" Body="&lt;p&gt;On &lt;a href=&quot;https://puzzling.stackexchange.com/&quot;&gt;Puzzling.SE&lt;/a&gt; I found &lt;a href=&quot;https://puzzling.stackexchange.com/questions/10700/building-a-2-mile-runway-on-1x1-mile-private-island&quot;&gt;this question:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You have a 1 mile long x 1 mile wide private island that you wish to&#xA;  turn into a resort. A plane requires a 2-miles long runway to take&#xA;  off. What do you do?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are plenty of answers, among them some irrational ones, but also some good approaches to solving this puzzle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;From an aeronautical point of view, what would be a reasonable solution?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am thinking about a vertically curved runway. To meet the 2 mile requirement it would need to have an angle of (estimated) 25° at the edges of the curved runway. It would go diagonally across the island and by its curvature add the extra length needed to the √ 2 length of the diagonal length. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am sure there must be a better solution though (extensions of the island shouldn't count!)&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:50:46.507" LastActivityDate="2017-01-18T08:46:03.623" Title="How to build a 2 mile long runway on a 1 mile square island?" Tags="&lt;runways&gt;&lt;theory&gt;&lt;airport-design&gt;" AnswerCount="7" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13386" PostTypeId="2" ParentId="13385" CreationDate="2015-03-22T04:35:18.857" Score="6" Body="&lt;p&gt;I will go through some answers of the puzzle, some rational, some not:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Add a third dimension (i.e. sloped diagonal runway):&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Your plane will be going downslope at a 45 degree angle. It will pick up speed pretty fast, but requires a skillful pilot to pull it out of the dive before hitting water. Not very practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you go upslope, your pitch up will be 45 degrees and you will likely have insufficient engine power to maintain airspeed (not to mention accelerate). Not feasible either.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Do we really need 2 miles?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If the plane needs 2 miles due to the low acceleration of the engine, then we can use a bit of slope (e.g. 5 or 10 degrees) instead of 45. A fully vertical acceleration gives 9.8 ms&lt;sup&gt;-2&lt;/sup&gt;. A 10 degrees slope will give the plane an additional acceleration of $9.8 sin(10^\circ)$ ms&lt;sup&gt;-2&lt;/sup&gt; on top of the acceleration given by the engine. This has the hope of significantly shortening the takeoff distance if the engine is weak.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aircraft Catapult&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;This one has been done practically, given a strong enough catapult and reinforced aircraft frame.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;My personal answer...&lt;/h1&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; Wait for enough head wind to takeoff!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1961" LastEditDate="2015-03-22T19:57:48.333" LastActivityDate="2015-03-22T19:57:48.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13387" PostTypeId="2" ParentId="13385" CreationDate="2015-03-22T05:26:35.057" Score="6" Body="&lt;p&gt;There really isn't a better answer than &quot;extending the island.&quot; To function, runways must be straight (or very nearly so, a half-mile radius of curvature is unacceptable at takeoff speeds), and level (or very nearly so, gradients are measured in percent and 11% is an extreme gradient, which still gets you very little extra length). However, aircraft carriers in a lot of countries have ski-jump ramps which seem to go up to 12 degrees (20% gradient or so, let's be generous and say 15 degrees), which means that's probably a good absolute limit on the slope of the runway &lt;em&gt;anywhere&lt;/em&gt; (it doesn't work on the whole runway, but this is irrelevant). Let's look at some numbers. We'll start with the longest possible flat runway, and then put it at the highest possible slope, to get an upper bound on length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The largest radius of curvature you can have horizontally is 1 mile; this is also a very high radius of curvature (around what the Endless Runway people have; a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1898/could-you-land-a-large-airplane-on-short-circular-runways#comment3497_1931&quot;&gt;comment&lt;/a&gt; on the curved runways question calculates that at takeoff speed, you need the equivalent of a 20-degree bank to stay on this runway), so anything tighter won't be acceptable. This gives you $2\pi/4\approx1.57$ miles; this is the longest possible flat runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might also curve up while doing this; the maximum slope at any point is 15 degrees. The longest way to do this is to have a constant 15-degree slope; this means that the max possible length, with tight horizontal curvature and a ridiculous slope, is $1.57/\cos 15^\circ\approx1.63$ miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there you have it. The maximum length available, with extremely generous slope and curvature constraints, is well under 2 miles.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-22T05:26:35.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13388" PostTypeId="2" ParentId="13385" CreationDate="2015-03-22T06:16:43.713" Score="59" Body="&lt;p&gt;Anyone who has ever flown at Zar (EPZR) in Poland knows how much a runway slope can reduce the needed field length. For aircraft which need a 2 miles long level runway, a 1 mile long one with a 15% slope at its end will do just fine. Make the slope shallow at the bottom and increase it the further up the runway goes, just like the hillside runway at Zar. If the end point is 183.5 m higher than the touch-down point, the height difference is equivalent to a speed reduction from 60 m/s to zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take-offs work in the opposite way, giving the same speed boost on the way down. A 1 mile long runway will do just fine. You do not even need to run it diagonally across the island.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, this does not exactly answer the riddle, but is an engineering solution to a simple problem.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-22T15:30:05.723" LastActivityDate="2015-03-22T15:30:05.723" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13389" PostTypeId="2" ParentId="1087" CreationDate="2015-03-22T08:43:22.220" Score="-3" Body="&lt;p&gt;Read below with a grain of salt, as I'm not a CFII.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I understand, there are no &quot;precision&quot; GPS approaches, aside from CAT1,2,3. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;LPV is more accurate, uses WAAS, and means LP with vertical guidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LNAV/VNAV is an older tech, and was originally designed before WAAS was available. Before WAAS, aircraft with flight management/director systems were equipped to fly LNAV/VNAV. The VNAV portion consisted of Baro-VNAV equipment requirements. Nowadays, you can buy some newer aircraft equipped with Baro-VNAV, or fly those approaches with capable WAAS GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, you should read your aircraft manual and check it's equipment and what approaches it's qualified for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a &lt;a href=&quot;http://www.duncanaviation.aero/straighttalk/waas/faqs-operational.php&quot; rel=&quot;nofollow&quot;&gt;link to more info&lt;/a&gt; I found.&lt;/p&gt;&#xA;" OwnerUserId="7726" LastEditorUserId="19" LastEditDate="2016-07-05T06:43:52.943" LastActivityDate="2016-07-05T06:43:52.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13390" PostTypeId="2" ParentId="13332" CreationDate="2015-03-22T08:50:25.510" Score="0" Body="&lt;p&gt;No. &quot;Flying&quot; has come to refer to the non-intuitive or 'magical' mechanisms of travel through air - and that 'miracle of flight' is Bernoulli at work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rockets and balloons can only go straight up, they cannot fly (ie. travel horizontally). Well I suppose jet packs count. I do not think we should call that flying. &quot;Jetting&quot; maybe ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We could categorise ways of getting about in air as:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flying. Bernoulli pressure differential devices (including propellors).&lt;/li&gt;&#xA;&lt;li&gt;Scooping. Things which mechanically displace the air to support or propel them -  paddles/scoops/augers/blades/flat wings (are there any working examples which do not also use Bernoulli? Maybe insects? Did anyone work out yet how bees fly?)&lt;/li&gt;&#xA;&lt;li&gt;Positive Impulse. Things which create new air [or gas] to support or propel them - Rockets, steam jets, photon rockets&lt;/li&gt;&#xA;&lt;li&gt;Negative Impulse. Things which destroy air in front to support or propel them - not sure if anyone has made a supercooler negative impulse engine but I presume it works in theory (it would have to squirt out liquid air which would be type 2 thrust as it expanded ..)&lt;/li&gt;&#xA;&lt;li&gt;Anti gravity devices. Would move sideways by interacting with planets.&lt;/li&gt;&#xA;&lt;li&gt;Magnetic levitation - close range only.&lt;/li&gt;&#xA;&lt;li&gt;Floating. Balloons do not really count as flying though because they cannot move sideways without using other principles. &lt;/li&gt;&#xA;&lt;li&gt;Riding. Wind (kites,leaves) , convection currents (house dust) or thermals (gliding, clouds).&lt;/li&gt;&#xA;&lt;li&gt;Jumping ( or getting from a to b quick before gravity kicks in ). I think in this category we also have electromagnetic radiation - which does a good job of 'flying' long distances very quickly and has been around a long time.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So 'No' is probably the answer.&lt;/p&gt;&#xA;" OwnerUserId="7727" LastEditorUserId="7727" LastEditDate="2015-03-22T09:55:44.990" LastActivityDate="2015-03-22T09:55:44.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13391" PostTypeId="2" ParentId="8577" CreationDate="2015-03-22T12:35:49.017" Score="0" Body="&lt;p&gt;(I will note that I am NOT a pilot, only an enthusiast.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kevin's answer appears to be the most correct one, without giving the actual CORRECT answer. The only correct answer is to perform whatever emergency procedures are contained within the POH, or Pilot's Operating Handbook for the aircraft you are flying, coupled with any revisions, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Please note, the following links are to scanned in copies of the POH's, and are not links to the manufacturers websites, but to private companies)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did some quick research, and three aircraft, specifically the &lt;a href=&quot;http://mfgl.lspl.ch/fileadmin/mfgl_content/Download/HB-PQY_POH_Rev_24.pdf&quot; rel=&quot;nofollow&quot;&gt;Piper Arrow PA-28R-201&lt;/a&gt;, the &lt;a href=&quot;http://www.redskyventures.org/doc/cessna-poh/Cessna_210_C210M_Centurion_POH_1977_Sections%201-8_scanned.pdf&quot; rel=&quot;nofollow&quot;&gt;Cessna 210M Centurion&lt;/a&gt;, and the &lt;a href=&quot;http://www.redskyventures.org/doc/cessna-poh/Cessna_421C_C421C_GoldenEagle_POH-AFM_.pdf&quot; rel=&quot;nofollow&quot;&gt;Cessna 421C Golden Eagle&lt;/a&gt;, all have emergency gear up procedures. In all three cases the procedure includes ignition off, magneto's off and fuel off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may very well be an aircraft whose POH indicates full power and fuel during emergency gear up landings. However, the only way for that to be the &lt;em&gt;correct&lt;/em&gt; procedure is for some documentation to &lt;em&gt;say&lt;/em&gt; it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, no where am I suggesting that during an emergency you pull out the POH and read it. Very contrary, I am suggesting that you read and re-read the applicable documentation &lt;em&gt;for the aircraft you are flying at the moment&lt;/em&gt; until you are very familiar with it.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-03-22T12:35:49.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13392" PostTypeId="2" ParentId="13278" CreationDate="2015-03-22T14:40:29.580" Score="3" Body="&lt;p&gt;Disclaimer: I am a copter pilot, but not a designer&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotor generates a certain amount of torque that would swing the body in the opposite direction of the turning rotor (Newton III). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pedals are called anti-torque pedals, which counteract this behavior, and allow the body of the copter to be yawed independently of the rotor.  In a copter which has either a tail rotor or a ducted fan (rather than two main rotors), the amount of force generated by the tail must be sufficient to allow a 360 degrees of yaw in nearly any regime of flight. Increasing the distance between the main rotor and the tail rotor increases the effectiveness of the anti-torque pedals. A longer tailboom would allow a smaller tail rotor, and require less engine power to be diverted by the transmission, and vice-versa.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-03-22T14:40:29.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13393" PostTypeId="2" ParentId="572" CreationDate="2015-03-22T14:53:02.887" Score="0" Body="&lt;p&gt;In turbocharged engines, the impeller spins very fast (25,000+ RPM), has very small tolerances, and operates at EGT temps (since the compressor is driven by the exhaust gas). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the M20M (turbo Mooney) manual, these engines must be given a 5-minute cool-down period to ensure that the oil continues to circulate through the turbo, and carry away the heat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I fly this plane is to &lt;em&gt;reduce&lt;/em&gt; the mixture at the same time as the power when beginning the descent, in order to keep the temps up, and to increase the mixture slowly during the descent to bring the engine temps down.  Then at shutdown, I run the engine with the throttle completely back, and allow all the temps (CHT, EGT, oil, and TIT) to stabilize.  Once the temps are stabilized at the lowest power setting, no more heat can be extracted from the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9FChe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-03-22T14:53:02.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13394" PostTypeId="2" ParentId="13385" CreationDate="2015-03-22T16:44:23.577" Score="10" Body="&lt;p&gt;A seaplane would be a suitable solution.  Then the only infrastructure required on the island is a jetty and fuel/servicing.&#xA;This also enables a much larger aircraft and so easier cargo resupply and a longer range on the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="7728" LastEditorUserId="7728" LastEditDate="2015-03-26T08:19:10.400" LastActivityDate="2015-03-26T08:19:10.400" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13395" PostTypeId="1" AcceptedAnswerId="13399" CreationDate="2015-03-22T16:48:19.623" Score="6" ViewCount="450" Body="&lt;p&gt;Both the FAA and the EASA have decided against using ADS-C in the development of NextGen and SESAR, because of cost, scalability and ease of use. But has ADS-C actually been implemented and used in practice anywhere?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-03-22T22:01:07.837" Title="Is ADS-C used in practice?" Tags="&lt;ads-b&gt;&lt;ads-c&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13396" PostTypeId="2" ParentId="12626" CreationDate="2015-03-22T16:53:41.217" Score="6" Body="&lt;p&gt;Practically there are no zero visibility landings.  There is reduced visibility of varying levels.  Reduced visibility landings are only allowed when the appropriate ILS equipment is operational.&#xA;The practical issues are actually not the landing itself but separation from aircraft landing afterwards.  On the ground the runway lights are bright enough and close enough for slow navigation.  However the aircraft takes longer to clear the runway and this means increased separation between landing aircraft is required.   It is this that causes delays as aircraft waiting to land are pushed further and further back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ground tug to facilitate speedy removal of the aircraft from the runway makes sense in theory, but would be hazardous and the acquisition time wold be non trivial.  While an estimated stopping location could be calculated for an aircraft finishing its roll out after landing it would be subject to a very large variation and the tug would have a large distance to cover to get to the aircraft.  It would then have to connect and start the tow.  The question is whether this wold be quicker than the current arrangement and what the mass penalty would be in terms of changes to the aircraft structure to enable it to use the tug. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In response to comments I would like to clarify that my point about the acquisition time of the aircraft by the tug is concerned with the non trivial and varying distance the tug would need to cover to reach the aircraft.  Any tug configured to pull an aircraft weighing in excess of 100tons would need to be large, heavy, and have high torque to help it safely move the aircraft.  These are all things which will reduce its top speed and so increase the time it takes to get to the aircraft from some optimal starting location.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Multiple tugs:&lt;/strong&gt;&lt;br&gt;&#xA;Multiple tugs would increase the probability that the aircraft would stop within optimal distance of one of them but would also increase the collision risk and add complexity to the local airflow over the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Starting locations:&lt;/strong&gt;&lt;br&gt;&#xA;To facilitate quick response and removal of the aircraft from the runway the tugs would need to be located close to hand.  However they cannot be on the runway and would be required to be back from the edge by a significant distance.  When you consider the finite number of taxiways and the sheer variation in aircraft roll outs this presents a very wide range in possible locations the tug would need to get to with a consequential increase in response times.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aircraft Rollouts:&lt;/strong&gt;&lt;br&gt;&#xA;When an aircraft lands it typically uses a small amount of remaining velocity to keep it rolling and move off the runway.  This would almost always be quicker than waiting for a tug.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Hybrid tug system:&lt;/strong&gt;&lt;br&gt;&#xA;A hybrid system in which the aircraft uses residual speed to clear the runway and meet a tug has some advantages in terms of optimal tug positioning however it reduces the advantages in fuel consumption and increases the amount of vehicles independently moving around the airfield.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7728" LastEditorUserId="14897" LastEditDate="2019-11-18T21:16:43.030" LastActivityDate="2019-11-18T21:16:43.030" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="13397" PostTypeId="1" AcceptedAnswerId="13398" CreationDate="2015-03-22T20:24:57.757" Score="34" ViewCount="8132" Body="&lt;p&gt;I was just watching the &lt;a href=&quot;http://thetvdb.com/index.php?tab=episode&amp;amp;seriesid=121511&amp;amp;seasonid=137891&amp;amp;id=4460474&quot;&gt;&lt;em&gt;James May's Toy Stories&lt;/em&gt; Christmas Special &lt;em&gt;Flight Club&lt;/em&gt;&lt;/a&gt;&lt;sup&gt;*&lt;/sup&gt;, and in it he commented that the helicopter was making a spiral climb to 8,000'.  Why would the pilot spiral, not just essentially go straight up?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;* An excellent series if you're a big kid who enjoys toys, and as a bunch o' GA pilots, I'd think that covers most of you!&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2019-03-24T02:05:50.280" Title="Why would a helicopter climb in a spiral?" Tags="&lt;helicopter&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13398" PostTypeId="2" ParentId="13397" CreationDate="2015-03-22T21:03:12.443" Score="56" Body="&lt;p&gt;A helicopter will achieve its best climb rate at a moderate forward speed. Climbing in a spiral helps to have forward speed in what is essentially a vertical climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a hover all the airflow which is available for lift creation must be generated by the rotation of the main rotor. This means that a small amount of air must be accelerated by a lot. If the helicopter adds forward speed, it can achieve a higher mass flow through the rotor, and now less acceleration is needed to achieve the same lift. This improves the efficiency of lift creation. If the helicopter goes faster than its speed for maximum rate of climb, aerodynamic drag grows too high and reduces efficiency again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference can be dramatic: Below is a plot of the speed versus altitude of a generic helicopter and turboprop plane in comparison to the V-22 tilt rotor. Remember that the available power is roughly proportional to air density, and you can start to see how much more power is available for climbing when the helicopter flies with a moderate forward speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RWmdQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RWmdQ.jpg&quot; alt=&quot;Flight envelopes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight envelopes of a generic helicopter, a turboprop plane and the V-22 tiltrotor (picture &lt;a href=&quot;http://imagery.vnfawing.com/archive/Helicopters/V-22/p0051561.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Thanks to @mins for inspiring me to expand the answer a little.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-28T19:55:54.627" LastActivityDate="2015-10-28T19:55:54.627" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13399" PostTypeId="2" ParentId="13395" CreationDate="2015-03-22T21:53:59.147" Score="8" Body="&lt;p&gt;ADS-C is used in oceanic environments, for example over the Atlantic and the Pacific.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FL350 to FL390 on the North Atlantic Track System is restricted to ADS-C equipped aircraft. Non ADS-C aircraft have to fly either below or above those levels (crossing through those levels is permitted) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The text below is a part of today's Norht Atantic Track message issued by Shanwick Center (EGGX): &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;222021 EGGXZOZX&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(NAT-2/2 TRACKS FLS 310/390 INCLUSIVE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;MAR 23/1130Z TO MAR 23/1900Z&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PART TWO OF TWO PARTS-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;E MALOT 53/20 53/30 53/40 53/50 RIKAL&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EAST LVLS NIL&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;WEST LVLS 310 320 330 340 350 360 370 380 390&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EUR RTS WEST NIL&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NAR NIL-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;F LIMRI 52/20 52/30 52/40 52/50 TUDEP&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EAST LVLS NIL&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;WEST LVLS 310 320 330 340 350 360 370 380 390&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;EUR RTS WEST NIL&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NAR NIL-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;REMARKS.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;TMI IS 082 AND OPERATORS ARE REMINDED TO INCLUDE THE&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;TMI NUMBER AS PART OF THE OCEANIC CLEARANCE READ BACK.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2. ADS-C AND CPDLC MANDATED OTS ARE AS FOLLOWS&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK A 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK B 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK C 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK D 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK E 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;TRACK F 350 360 370 380 390&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;END OF ADS-C AND CPDLC MANDATED OTS&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-22T22:01:07.837" LastActivityDate="2015-03-22T22:01:07.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13400" PostTypeId="2" ParentId="13397" CreationDate="2015-03-22T21:58:32.910" Score="13" Body="&lt;p&gt;In the spiral, the helicopter generates &lt;a href=&quot;http://en.wikipedia.org/wiki/Translational_lift&quot;&gt;translational lift&lt;/a&gt;, which is added to the lift generated by the downwash of the rotor system, improving its ability to climb. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-03-22T21:58:32.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13401" PostTypeId="1" CreationDate="2015-03-22T21:58:59.060" Score="12" ViewCount="2340" Body="&lt;p&gt;I'm especially interested how long it would take to restart a turbofan engine after a hypothetically erroneous shutdown of an engine immediately after takeoff i.e., at an altitude at which the air is reasonably dense. Is windmilling enough or would you need crossbleed and starters again?&lt;/p&gt;&#xA;" OwnerUserId="7730" LastEditorUserId="946" LastEditDate="2015-03-23T10:22:28.017" LastActivityDate="2015-03-26T15:53:26.773" Title="How long does it take to restart a turbofan engine inflight?" Tags="&lt;emergency&gt;&lt;jet-engine&gt;&lt;engine-starting&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13402" PostTypeId="2" ParentId="434" CreationDate="2015-03-22T22:09:57.893" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;you're always told not to cross-control&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This should not be what you're taught. You should fly in &lt;em&gt;coordinated&lt;/em&gt; flight, and that can often mean being cross-controlled. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two very common examples of coordinated, cross-controlled flight are left hand turns on take off and steep turns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of p-factor, on departure, you will have some amount of right pedal in, but to turn left (particularly in a nosewheel airplane), you need left aileron while you still have right pedal in, and its not unusual for full-power climbing left turns to have left aileron and right pedal in coordinated flight. You'll see this more in a high-performance airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second example is steep turns. After you roll into a steep turn to the left, say, the over-banking tendency will require right aileron with left pedal to keep the plane from increasing bank angle, in coordinated flight. The over-banking tendency is less pronounced below 45 degrees of bank in low aspect-ratio aircraft, like your typical Cessna.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the rule is not &quot;don't cross-control,&quot; but rather &quot;fly coordinated&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the easiest way to get a plane into a spin is full cross control, and pull back on the stick. That's probably why you're taught never to do it.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-03-22T22:22:53.280" LastActivityDate="2015-03-22T22:22:53.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13403" PostTypeId="1" CreationDate="2015-03-22T23:18:28.027" Score="6" ViewCount="371" Body="&lt;p&gt;Recently, when I requested tower enroute service from a Southern California airport with published &lt;a href=&quot;http://en.wikipedia.org/wiki/Tower_en_route_control&quot;&gt;TEC routes&lt;/a&gt;, I was told by the controller that, out of courtesy for him, I needed to prefile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I wanted to push the issue, would the regulations have been on his side, or mine? What good is TEC if it has to be prefiled?  &lt;/p&gt;&#xA;" OwnerUserId="7488" LastEditorUserId="65" LastEditDate="2015-03-23T15:12:59.157" LastActivityDate="2015-03-23T15:12:59.157" Title="Can ATC decide whether or not to provide tower enroute services?" Tags="&lt;faa-regulations&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13404" PostTypeId="2" ParentId="13403" CreationDate="2015-03-23T00:02:19.477" Score="7" Body="&lt;p&gt;According to the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0401.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM, 4-1-19-c&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are no unique requirements upon pilots to use the TEC program. Normal flight plan filing procedures will ensure proper flight plan processing. Pilots should include the acronym “TEC” in the remarks section of the flight plan when requesting tower en route control. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on that, it would seem that the TEC request was essentially equivalent to that of getting a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1361/how-do-you-request-a-pop-up-ifr-clearance&quot;&gt;pop-up IFR clearance&lt;/a&gt;. If you pre-file, the controller has all the information necessary to enter you into the system rather than asking for it over the radio. It wouldn't be legally required, but neither would the controller be required to issue a clearance if workload doesn't permit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When using a TEC route, there is still the benefit of only talking to local controllers, and using a known routing that you're less likely to have amended.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-23T00:02:19.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13405" PostTypeId="2" ParentId="13385" CreationDate="2015-03-23T00:50:18.523" Score="1" Body="&lt;p&gt;The answer is to extend the island, the main issue I see here is that you really cant change any of the other variables. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A catapult wont work because (as far as I know) modern airlines do not have the airframe necessary to support this. Then again I may be wrong but I would think they could not take that kind of force. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea how a ski jump like slope would affect an aircraft. I know they have them on aircraft carriers so maybe someone could weigh in on how that works both for plane size and the effect it has on the airframe from a force on the gear perspective. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sea planes would still require people to come into a local airpot and take a smaller seaplane to the island assuming it was near a larger airport. Or take a sea plane of a certain vintage, capable of flying long distances. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extending the runway (depending on the surrounding sea bed) is not very difficult and has been done. KIX in hong kong is build on a completely man made island so adding some land to the end of the island it not a big deal. I also add this since I assume you want the ability to fly direct to the island and not have to fly to a larger airport then take a small plane into the island.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-23T00:50:18.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13407" PostTypeId="2" ParentId="13401" CreationDate="2015-03-23T07:35:18.130" Score="8" Body="&lt;p&gt;It can take from a few seconds to eternity. If the core cools down, &lt;a href=&quot;http://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701&quot;&gt;the engine might lock up&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Windmilling starts are only possible if the aircraft is flying &lt;a href=&quot;http://en.wikipedia.org/wiki/Kegworth_air_disaster&quot;&gt;fast and low enough&lt;/a&gt;. It will assist the startup process, but needs additional help from the starter or bleed air, typically below 300 knots and above 20,000 ft. Details vary from type to type. If everything works as designed, a windmilling assisted restart is faster than a regular engine start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ability to restart in flight must be proven as part of the certification process. However, right after takeoff the speed is too low for a pure windmilling start, and an additional energy source is needed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-23T15:55:18.370" LastActivityDate="2015-03-23T15:55:18.370" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13409" PostTypeId="2" ParentId="13397" CreationDate="2015-03-23T09:51:36.520" Score="13" Body="&lt;p&gt;See my &lt;a href=&quot;https://aviation.stackexchange.com/questions/11966/why-was-i-getting-an-uncomfortable-feeling-in-an-r22-at-3-000-feet&quot;&gt;question here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I performed a spiral climb is for the reasons given above plus a couple more.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Forward speed is safety.  In the event that the engine should quit, having forward speed gives you a lot more options.  When climbing vertically, you have a lot more pitch on the blades than in forward flight.  If the engine does quit, the blades will slow down very quickly reducing the time available for the pilot to dump the collective and enter autorotation.  You are also storing kinetic energy, as well as potential energy, in the system and therefore have more energy to play with if the donkey does go quiet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the R22 I was flying, I would probably have about one second to react correctly in a vertical climb.  Perhaps 2-2.5 in forward flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I wanted to remain clear of the danger area since I didn't have a clearance and had limited options for flying around the sides.  I did ensure that I was not over any houses and moved the spiral a couple of times so that my noise footprint was not over the same spot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-03-24T14:01:19.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13411" PostTypeId="1" CreationDate="2015-03-23T13:22:34.513" Score="5" ViewCount="817" Body="&lt;p&gt;How does conventional flight work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Explain what factors are in play in order to get a plane airborne and stay there.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-24T00:40:28.793" LastActivityDate="2015-03-28T18:04:49.220" Title="What makes an airplane fly?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13412" PostTypeId="2" ParentId="13411" CreationDate="2015-03-23T13:23:33.763" Score="7" Body="&lt;h1&gt;Four Fundamental Forces&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Weight&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Weight&lt;/em&gt; is the force of gravity acting upon an object's mass.  The mass of an airplane is the sum of all parts that make up the airplane, including fuel and lubricating oils, crew/passengers, and cargo.  In a normal flight attitude, this force acts in the &lt;strong&gt;down&lt;/strong&gt; direction, and it will always act towards the earth's center of gravity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane's &lt;em&gt;center of gravity&lt;/em&gt;, or &lt;em&gt;CG&lt;/em&gt;, is the location where the aircraft's mass/weight is evenly distributed in all directions.  Optimally, the CG should be as close as possible to the airplane's center of lift.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Lift&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In a normal flight attitude, &lt;em&gt;lift&lt;/em&gt; is the force opposing weight, acting in the &lt;strong&gt;up&lt;/strong&gt; direction.  It is produced by the interaction of the wings and fuselage with the surrounding air as the aircraft travels through.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three scientific principles at work in the production of lift as it applies to aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Bernoulli's Principle&lt;/em&gt;: &lt;strong&gt;As air travels faster, its pressure decreases&lt;/strong&gt;.  A typical airplane wing is designed like a foil, where the upper surface is comparatively rounder than the lower surface.  Air flows faster and at lower pressure over the top of the wing than air flowing underneath it, actually arriving somewhat earlier at the trailing edge than the air traveling underneath the wing.  This pressure difference accounts for most of the lift, but not all.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The &lt;em&gt;Coandă Effect&lt;/em&gt;: &lt;strong&gt;Airflow is attracted to nearby surfaces&lt;/strong&gt;.  Air &quot;hugs&quot; the wing as the wing passes through it.  Additionally, since the airflow over the wing is faster than that below the wing, the net result after the wing has passed through is &lt;strong&gt;downward&lt;/strong&gt; air movement.  As the wing angle relative to the initial airflow (the &lt;em&gt;angle of attack&lt;/em&gt;) increases, the trailing airflow is increasingly deflected downward.  (However, too much angle of attack will result in disrupted airflow on the leeward side of the wing, causing the wing to &lt;em&gt;stall&lt;/em&gt;, resulting in a loss of lift.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Newton's Third Law of Motion&lt;/em&gt;: &lt;strong&gt;A force in one direction caused &lt;em&gt;by&lt;/em&gt; an object is countered by an equal force &lt;em&gt;upon&lt;/em&gt; that object in the opposite direction&lt;/strong&gt;.  Air deflected downward off the trailing edge of the wing results in a simultaneous &lt;strong&gt;upward&lt;/strong&gt; force on the wing itself.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Drag&lt;/em&gt; is the force of all friction acting upon the airplane, operating in the &lt;strong&gt;backward&lt;/strong&gt; direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag comes in many varieties.  &lt;em&gt;Skin friction&lt;/em&gt; is the resistance caused by moving a solid object (the plane itself) through the air.  &lt;em&gt;Induced drag&lt;/em&gt; occurs at the wingtips, where the high pressure air below the wing flows into the low pressure region above the wing, creating inwardly rotating swirls of air (&lt;em&gt;vortices&lt;/em&gt;) behind the airplane.  Additional drag is encountered as an airplane's speed approaches the speed of sound and beyond.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Thrust&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Thrust&lt;/em&gt; is the force causing the aircraft to move &lt;strong&gt;forward&lt;/strong&gt; through the air.  In most airplanes, thrust is produced by a propeller or jet engine.  This is &lt;em&gt;Newton's Third Law&lt;/em&gt; in effect as well: as air is pushed backward, the aircraft moves forward.  This forward motion creates a flow of air over the wing, producing lift.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airplane's thrust produced equals its drag, the airplane remains in level flight (barring any pilot control inputs).  When thrust exceeds the drag, the increased airflow over the wing creates additional lift.  When thrust is less than drag, the decreased airflow results in less lift being generated.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-24T00:37:58.400" LastActivityDate="2015-03-24T00:37:58.400" CommentCount="3" CommunityOwnedDate="2015-03-23T13:23:33.763" ContentLicense="CC BY-SA 3.0" />
  <row Id="13414" PostTypeId="2" ParentId="3321" CreationDate="2015-03-23T16:40:58.710" Score="3" Body="&lt;p&gt;The other answer to this is just how I would have said it however I will respond to your second point of electronic failure and what you can do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off I am sure you know that airplanes carry a great amount of redundancy to avoid this and the changes of everything failing is almost 0 but lets say it does happen. I will go through what you can do and what backups you have. First lets talk GA VFR situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am only VFR rated and fly only single engine planes. When it comes to navigation I have 2 options, paper maps, and no the electronic flight bag which I have just moved to. When I fly i carry my iPad (with external GPS receiver) and my iPhone. Both have the east half of the country worth of maps and procedures/info downloaded to them and independent GPS receivers. My pre-flight starts the night before making sure I have everything charged up. Now I'm in the plane my iPad overheats or crashes, I move to my phone, buys me another 30 min then it crashes, I move to my paper maps, compass and stop watch. As for stop watches I usually have 3, a chronograph on my watch, a hand held mechanical, and the one mounted in the plane (some times there are 2 mounted depends on what I am renting that day). This allows me to fly dead reckoning to my destination using my map, plotter and flight computer. Again doing some guesstimating in my head and some quick calculations. Now lets say for some reason none of my stop watches are working, my maps flew out the window, and I dont know any of the VOR frequencies in the area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look out the window until you see a landing strip, then buy some new maps... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets move to some bigger planes. Large planes carry numerous electronic navigation aids. Along with using GPS, they have inertial navigation systems which are capable of working on their own. Although inaccurate (by today's standards) they will tell you how far/fast you have traveled from which you can extrapolate location. Since commercial planes fly under IFR most of the time, assuming one of the radios on the plane is functional ATC can guide them down assuming all of their equipment is no longer working. Again in the end of the day physical maps will get you where you need to be although I dont know if large planes carry VFR maps along with their IFR route charts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again the key here is redundancy and the fact that its highly unlikely that all systems on a plane will fail simultaneously. That being said even if it does happen the pilot should have a fair idea of where they are/where they are going and should know a general compass heading to divert to another airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically navigation equipment was also more cumbersome than the iPad I have on my knee board and knowledge aside, a navigator simply provided another set of hands and eyes to operate the devices which were often mounted behind the pilot. There is only so much display area on an aircraft dash for gauges and devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth its also worth noting that flight engineers are on their way out now. The 747 which once required an engineer eliminated the need with the 747-400 variant by including glass cockpits making everything available to the pilots. If you read up on the early days of aviation you will also find that pilots were often their own mechanics, fixing the planes at stops and what not. In a way its not that we don't need the position it's that the task has been offloaded elsewhere.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-03-24T13:27:24.977" LastActivityDate="2015-03-24T13:27:24.977" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13416" PostTypeId="2" ParentId="1833" CreationDate="2015-03-23T18:37:58.293" Score="9" Body="&lt;p&gt;Originally (way back before radar) the colors had a practical use for maintaining visual separation between planes, which was done by pilots looking for the other planes with their eyes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dark underbelly&lt;/strong&gt;: Easier to see from below against bright clouds or sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Light top-body&lt;/strong&gt;: Easier to see from above against (typically) dark ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea being that when you're looking visually for other civilian air traffic (or from the ground) one wants to maximize visibility without losing them in sky glare or ground clutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at older &lt;strong&gt;military&lt;/strong&gt; planes you'll often see the &lt;strong&gt;exact opposite&lt;/strong&gt; (dark colors on top and blue on the bottom) because those military planes didn't want to be seen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y2k1J.jpg&quot; alt=&quot;A plane meant to be hard to see from above against forests of Europe and hard to see from the bottom against the sky&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7688" LastEditorUserId="7688" LastEditDate="2015-03-23T18:44:02.253" LastActivityDate="2015-03-23T18:44:02.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13418" PostTypeId="2" ParentId="13340" CreationDate="2015-03-23T23:50:23.243" Score="0" Body="&lt;p&gt;I've flown SVFR a lot. Like requesting access to military routes (MR on your area maps) it seems to be something that lots of people don't use but those who know how to use them discover they are great!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have found that traffic control (especially the non-tower sites you address as e.g. &quot;Radio Hawthorne&quot;) love hearing these requests and are eager to help you figure out the details you need to get what you want - probably because it's a bit more interesting than most of the requests they hear :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Caution, Opinion ahead&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I highly recommend you learn to use it and memorize a few of the versions more relevant to your location (e.g. &quot;SVFR to VFR on top&quot; to get above spotty low clouds). You'll sound like a pro and traffic control will usually be quite friendly and receptive about it. In fact I can't recall ever being turned down on such a request, although I have received advice to change my strategy once or twice (including once when I was guided into a channel to see about a dozen military craft go by at close enough range to count mustaches). SVFR is a fun and powerful tool for the general aviation pilot and an excellent way to build skill. Do them with your instructor too while you have the chance because they are indeed a &lt;strong&gt;skill&lt;/strong&gt; that is worth working on.&lt;/p&gt;&#xA;" OwnerUserId="7688" LastActivityDate="2015-03-23T23:50:23.243" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13419" PostTypeId="2" ParentId="12747" CreationDate="2015-03-24T01:21:23.347" Score="4" Body="&lt;p&gt;You can get a Pilot certificate under the Light Sport Category. This does not require a medical, only a current Drivers license. I've never seen a doctor for flying and I've had my ticket for a few years. You will be limited to VFR flight and aircraft size restrictions.(small plane, two seats to name few restrictions) But there are lots of options for Light Sport Aircraft, and many more manufactures getting on board with new equipment. Your CFI will teach you almost everything a beguining private pilot learns, because you have to be able to operate in the same airspace system with the rest of the VFR world. The training time requirements are less than PP and many pilots are starting with Sport and then moving up.&lt;/p&gt;&#xA;" OwnerUserId="7712" LastActivityDate="2015-03-24T01:21:23.347" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13420" PostTypeId="2" ParentId="9529" CreationDate="2015-03-24T04:24:51.273" Score="3" Body="&lt;p&gt;To go along with @ratchet freak's answer, machine parsing comes more into play when reporting maintenance status and readiness statistics, and for trend analysis - in other words, high-level aggregation and dissection of user-inputted data.  At this level, managers are more concerned with the number of aircraft available for use rather than the last time a particular aircraft's tires were &lt;strike&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/13093/6919&quot;&gt;kicked&lt;/a&gt;&lt;/strike&gt; changed.  Typically, this is all done using pricy electronic logbook software, and would be used by large organizations with lots of equipment to track and the money to employ such a system.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take, for example, the United States Army.  Its program of record for aviation maintenance and logistics is called &lt;strong&gt;Unit Level Logistics System-Aviation&lt;/strong&gt;, or ULLS-A for short.  This software suite automates a lot of the manual forms that the Army uses.  At the most basic level, aircraft maintenance is recorded using DA Form 2408-13-1, according to &lt;a href=&quot;http://www.apd.army.mil/jw2/xmldemo/p738_751/head.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;DA Pam 738-751&lt;/a&gt;.  The time and date of each status is compiled into a daily statistic, which is then rolled up into a monthly report, often only detailing (aside from the hours that aircraft was available for mission) what subsystem was responsible for the majority of each aircraft's downtime.  Here's what a blank maintenance form looks like:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/xtRiu.png&quot; alt=&quot;DA Form 2408-13-1&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, there are a multitude of blocks, each with its own list of codes.  For instance, here is a list of the codes for &lt;em&gt;WHEN DISC&lt;/em&gt; (when discovered), from &lt;a href=&quot;http://www.apd.army.mil/jw2/xmldemo/p738_751/main.asp#tab1-6&quot; rel=&quot;nofollow noreferrer&quot;&gt;Table 1-6&lt;/a&gt; of DA Pam 738-751:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;B   Handling&#xA;D   Sustainment facility (depot) level repair/overhaul/rebuild&#xA;E   Storage&#xA;G   Flight&#xA;H   Phase maintenance inspection (PMI, PPM, PMS2/3 and Reset)&#xA;J   Calibration&#xA;K   Unscheduled maintenance&#xA;L   Maintenance operational check&#xA;M   Maintenance test flight and/or functional check flight&#xA;N   AOAP results&#xA;O   Special inspection, scheduled maintenance&#xA;P   Diagnostic test (health and usage monitoring device and/or sytem)&#xA;Q   Servicing&#xA;R   Rearmament&#xA;S   Reconfiguration&#xA;T   Preflight inspection&#xA;U   Thru flight inspection&#xA;V   Post-flight inspection&#xA;W   Acceptance inspection&#xA;X   Daily/PMS/PMS1 inspection&#xA;Y   Intermediate inspection&#xA;Z   Periodic inspection  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;However, not all blocks are required to be filled out when using paper logbooks (believe it or not, still in use in some places); in addition to &lt;em&gt;WHEN DISC&lt;/em&gt;, &lt;em&gt;HOW REC&lt;/em&gt;, &lt;em&gt;MAL EFF&lt;/em&gt;, &lt;em&gt;WUC&lt;/em&gt;, &lt;em&gt;ACTION CODE&lt;/em&gt;, and &lt;em&gt;CAT&lt;/em&gt; are optional entries, and in practice never get used.  In contrast, these are required fields in ULLS-A, and so the system provides a number of helps to the user so he doesn't have to refer to the manual all the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, only these codes (and not the free text fault/remarks block) will be machine-parsed, for the purpose of high-level analysis to determine trends and/or systemic issues affecting the entire fleet.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-03-24T04:24:51.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13421" PostTypeId="1" AcceptedAnswerId="13436" CreationDate="2015-03-24T04:44:01.583" Score="13" ViewCount="6678" Body="&lt;p&gt;In an airplane which is only equipped with a beacon for anticollision lights (1967 Piper Cherokee, for this example), what is the effect of an inoperative beacon?  Obviously, per part 91.205, anticollision lights are required equipment for VFR Night.  But, since the aircraft was certificated before 1996, it is not required under 91.205 for VFR Day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the interesting part is, under 91.209, since the aircraft was equipped with anticollision lights, it sounds like the aircraft would not be airworthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The guidance I've heard on this seems to be conflicting.  One argument was since the equipment was disabled and placarded, it doesn't qualify.  Alternatively, in 91.213(d)(2)(iii) (also referenced by AC 97-61 figure 2), it states that if the equipment is required by part 91 FARs, (91.209 seems to apply here), it is unairworthy (and deactivating/placarding is not an option).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A final point of confusion, specific to this in example: the beacon was an optional feature of the 1967 Cherokee according to the manual... which brings me here: any other opinions, short of a more formal clarification? I'm inclined to err on the side of caution, especially since the definition of &quot;equipped&quot; isn't getting any clearer (other than seeing that little red light on there and the &quot;inop&quot; marking on the panel).&lt;/p&gt;&#xA;" OwnerUserId="2074" LastEditorUserId="1696" LastEditDate="2015-04-29T14:21:07.093" LastActivityDate="2015-11-16T20:53:51.993" Title="What are the legal effects of an inoperative anti-collision light?" Tags="&lt;faa-regulations&gt;&lt;aircraft-lighting&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13422" PostTypeId="1" AcceptedAnswerId="13437" CreationDate="2015-03-24T08:51:19.590" Score="40" ViewCount="29883" Body="&lt;p&gt;Imagine you're in a large jet on a long route on a major airway -- say, for example, you're in a 747 going LHR-JFK at night. It's dark, you're over the Atlantic, and ATC has cleared you to just keep on heading along at FL330 (or equivalent) for another ~1500 nautical miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it has throughout much of the flight, the autopilot is effectively flying the plane. There's nothing on the weather radar, no adverse meteorological effects expected, and ATC ensures that aircraft are well separated. In short, other than occasionally changing radio frequencies, there is very little for you to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just a week ago, you were in the simulator, practicing spin recovery, instrumentation inop procedures, engine failures epsilon before V&lt;sub&gt;1&lt;/sub&gt;, and all sorts of other &lt;em&gt;fun&lt;/em&gt; things that required your attention. In your spare time, you're a private pilot and enjoy flying VFR at lower altitudes with the occasional bit of aerobatics mixed in, and practicing what to do in all sorts of rare eventualities at odd attitudes. In other words, you like flying planes. Now, your job is to check that the sophisticated flight computers are still flying this plane, and that ATC have done their job properly. They are, and they have. For the next few hours, you're going to be doing nothing but sitting in a chair watching blackness roll past. You can't even talk to the guy next to you about the weather -- there isn't any!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do long-haul pilots cope with boredom on long, uneventful segments? Is my above scenario completely not plausible (aside from the lack of weather) -- is there always &lt;em&gt;something meaningful to do&lt;/em&gt; during a 7+ hour long flight? I would expect that pilot boredom or distraction would be a safety-critical situation, yet I cannot imagine a situation that involves two humans sitting in chairs in a small room for a long period of time where they will &lt;em&gt;not&lt;/em&gt; be bored or distracted at some point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do airline transport pilots ever &quot;hope&quot; for &quot;something interesting&quot; to happen?&lt;/p&gt;&#xA;" OwnerUserId="7499" LastEditorUserId="396" LastEditDate="2016-07-25T01:46:03.523" LastActivityDate="2018-05-09T12:04:05.110" Title="How do long-haul pilots cope with boredom?" Tags="&lt;airline-pilot&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13423" PostTypeId="1" AcceptedAnswerId="13424" CreationDate="2015-03-24T08:52:49.303" Score="17" ViewCount="3196" Body="&lt;p&gt;I was speaking with an ATP-rated pilot the other day, and he said something that sounded odd: basically the bigger aircraft has right of way once airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone shed some light on this? As far as I understand, ATC coordinates the landing/departing aircraft; at least at my airfield where there was MD80's, B738 and G/A.&lt;/p&gt;&#xA;" OwnerUserId="2330" LastEditorUserId="97" LastEditDate="2015-03-25T00:07:42.900" LastActivityDate="2015-03-25T00:07:42.900" Title="Is &quot;right-of-way&quot; based on aircraft size?" Tags="&lt;general-aviation&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13424" PostTypeId="2" ParentId="13423" CreationDate="2015-03-24T09:01:02.947" Score="18" Body="&lt;p&gt;The size of an aircraft plays no role in identifying who has right of way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general rule is that for same-class/type (powered or non-powered) aircraft, the aircraft coming from the right has right-of-way and should be yielded to. This is irrespective of the size within the same type, but a question of manoeuvrability. For different types of aircraft, a powered aircraft will have to yield to non-powered aircraft. For more details see the related question below, &lt;a href=&quot;http://www.icao.int/Meetings/anconf12/Document%20Archive/an02_cons%5B1%5D.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Annex II&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.2.4.7&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.113&lt;/a&gt; or another explanation in the &lt;a href=&quot;http://www.skybrary.aero/index.php/Right-of-way&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skybrary&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically, this means that where separation between IFR and VFR traffic is not provided and aircraft on both flight rules can operate, a Boeing 737 would have to yield to any powered or non-powered aircraft coming from the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most jurisdictions you will find a passage that also details that aircraft should give way to other aircraft that are established on final approach, so a strong situational awareness in the vicinity of airports and airfields is required. Whether separation is provided between IFR and VFR within a traffic pattern, is based on the jurisdiction and the airspace class. In most cases of smaller general aviation aircraft and larger/faster general aviation or commercial aircraft operating at uncontrolled airfields, the smaller aircraft will yield to the faster traffic already on the final approach path out of courtesy or due to &lt;em&gt;good airmanship&lt;/em&gt;. It is easier and also cheaper for a smaller general aviation aircraft to perform a 360° turn than for e.g. a Learjet on final approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See related question: &lt;a href=&quot;https://aviation.stackexchange.com/q/3575/572&quot;&gt;Which way should you turn to avoid another aircraft?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this YouTube video: &lt;a href=&quot;https://www.youtube.com/watch?v=uF8YiVOpfpA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane Right-of-Way Rules&lt;/a&gt; - Author: Humble Aviation&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-03-24T21:36:24.867" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13425" PostTypeId="2" ParentId="13423" CreationDate="2015-03-24T10:09:34.263" Score="13" Body="&lt;p&gt;The airborne aircraft right-of-way rules are based on maneuverability, not size. Balloons get first pass, then gliders, airships, powered parachutes &amp;amp; hang gliders, then powered aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exceptions include towing or refueling aircraft have right of way over the above, and anyone who declared an emergency has nominal right-of-way over them. Although I don't see the balloon rapidly departing the area just because someone said Mayday.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice the bigger aircraft will have right of way. A 747 just doesn't change course all that quickly but a Gulfstream will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC sequences arrivals and departures on a first-come, first serve basis with allowances for wake turbulence - they won't have a Cessna land immediately after a widebody.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="3386" LastEditDate="2015-03-24T10:13:54.713" LastActivityDate="2015-03-24T10:13:54.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13426" PostTypeId="1" AcceptedAnswerId="13427" CreationDate="2015-03-24T11:05:09.457" Score="5" ViewCount="2141" Body="&lt;p&gt;In the 2014 film &lt;em&gt;The Amazing Spider-Man 2&lt;/em&gt;, there's a sequence in which a villain disables the city's power grid.  All over town, stuff loses power... including the local airport and its air traffic controllers.  This is a problem because there are currently two planes inbound, on courses that will cause them to collide with each other in midair unless the tower can warn them in time!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luckily, Spider-Man finds a way to defeat the villain and the ATC gets their power back just in time to radio the planes to change course, and they miss each other by an extremely narrow margin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting aside for the moment the question of whether or not a real ATC would have their own independent backup power source, how realistic are the two premises of this crisis?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) That two airplanes would be inbound towards a major airport on courses that would cause them to both occupy the same position in 3D space at the same time, and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) That neither pilot would &lt;em&gt;actually notice this&lt;/em&gt; until either the tower told them or something suddenly goes &lt;strong&gt;&lt;em&gt;CRUNCH!&lt;/em&gt;&lt;/strong&gt;  Do commercial jet liners not have their own radar at the very least?  (Heck, my &lt;em&gt;car&lt;/em&gt; has little radar emitters that warn me if something is too close!)&lt;/p&gt;&#xA;" OwnerUserId="4221" LastActivityDate="2015-03-24T20:00:10.630" Title="How realistic is the aviation crisis in the recent Spider-Man movie?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13427" PostTypeId="2" ParentId="13426" CreationDate="2015-03-24T11:22:17.927" Score="8" Body="&lt;p&gt;This depends on the aircraft type, the flight rules and weather conditions as contributing factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger aircraft or medium sized aircraft operating under general aviation or commercial aviation will in many cases be equipped with a technology called Traffic Collision Avoidance System (TCAS) (See: &lt;a href=&quot;https://aviation.stackexchange.com/q/1883/572&quot;&gt;How does TCAS work?&lt;/a&gt;), which can instruct both aircraft to take evasive action if a collision is imminent. This is especially important in &lt;strong&gt;Instrument Meteorological Conditions&lt;/strong&gt;, where pilots do not rely on outside visibility, but on instrument flight only operating under &lt;strong&gt;Instrument Flight Rules&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;strong&gt;Visual Meteorological Conditions&lt;/strong&gt;, aircraft would likely be able to see each other and take evasive manueouvers without ATC or TCAS having to warn them, e.g. this is the case for smaller aircraft operating under &lt;strong&gt;Visual Flight Rules&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft receive clearances and instructions to occupy a certain flight level or altitude, sometimes coupled with clearances for approaches or arrival/departure procedures. If pilots do not receive further instructions, they will start to hold over their last clearance limit and commence lost radio/comms procedures, which include holding for a given amount of time and then beginning the descent towards the airport on defined and published approaches. If the power outage is long enough, the airspace is quite busy and all other frequencies are also unavailable, one of the being the distress or guard frequency, there is a probability that two aircraft on the same level will reach their clearance limit at some point and enter a hold at the same flight level, which could result in a collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scenario however assumes that really all failsafes and contingency procedures have failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also ths related question: &lt;a href=&quot;https://aviation.stackexchange.com/q/7599/572&quot;&gt;What happens when an airport shuts down?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-24T12:06:38.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13428" PostTypeId="1" AcceptedAnswerId="13429" CreationDate="2015-03-24T12:15:28.447" Score="106" ViewCount="21148" Body="&lt;p&gt;In the wake of &lt;a href=&quot;https://en.wikipedia.org/wiki/Germanwings_Flight_9525&quot; rel=&quot;noreferrer&quot;&gt;GermanWings' terrible incident of flight 9525&lt;/a&gt;, I have noticed that the crash location is quite far from the shortest route connecting the two airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I then went on FlightRadar24's website and checked that this is the normal route for this flight (and that there is an alternate one that reaches equally far on the other side):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bw25p.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UItCJ.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other companies that fly the same route (Vueling 1894, Airberlin 8947) follow the same flight paths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? What limitations are in place that prevent these aircraft from flying over Lyon (and &quot;nearby&quot; region)?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="22726" LastEditDate="2019-03-01T04:19:30.880" LastActivityDate="2019-03-01T04:19:30.880" Title="Why do airlines follow these routes between Barcelona and Düsseldorf?" Tags="&lt;airline-operations&gt;&lt;flight-planning&gt;&lt;flight-path&gt;&lt;france&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="13429" PostTypeId="2" ParentId="13428" CreationDate="2015-03-24T12:20:29.220" Score="130" Body="&lt;p&gt;Large parts of France's airspace are designated military training areas. If there is military flight training going on, the choice of routing over France is very limited. The only option is to fly around these areas, which  results in the routes you found. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/content/documents/nm/cartography/erc08h-05mar2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;Higher altitude route map of France courtesy of EUROCONTROL&lt;sup&gt;[PDF, 8MB]&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the PDF seems to be giving problems on some computers, I've combined several screenshots and drew the approximate route of your westerly flight (in yellow), the planned flight of GWI 9525 (blue) and Temporary Segregated Airspaces (TSA's) in red onto the map. The crash location of GWI 9525 is marked by a red/yellow star.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/hVW7e.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that not all the TSA's in the map are actively used at all times and that in some cases crossing is allowed but altitude restrictions apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to active TSA's there are other considerations that come into play such as weather and airway capacity &amp;amp; demand. If you have to wait 15 minutes longer for a slot on the shortest route, you might as well fly a slightly longer route if that allows you to depart earlier. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-26T13:26:45.680" LastActivityDate="2015-03-26T13:26:45.680" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13430" PostTypeId="1" AcceptedAnswerId="13433" CreationDate="2015-03-24T12:49:03.687" Score="13" ViewCount="3571" Body="&lt;p&gt;Two years ago I flew from Tel Aviv, Israel to Tromso, Norway via Riga and Oslo. The Tel Aviv-Riga leg was flown in an A320, and the Riga-Oslo and Oslo-Tromso legs were flown in prop planes, Fokker airplanes I think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What considerations are used to determine what type of plane will fly for a particular journey?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the choice would be limited to whatever aircraft the carrier has available, but given reasonable choice of any aircraft that seats the required amount of passengers, what considerations are used to decide on props or jets? Runway size? Fuel efficiency for short / long trips? Weather or temperature (both current and typical)?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="1696" LastEditDate="2018-04-15T02:22:34.323" LastActivityDate="2018-04-15T02:22:34.323" Title="Why would some flights use props instead of jets?" Tags="&lt;airline-operations&gt;&lt;jet&gt;&lt;turboprop&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13431" PostTypeId="2" ParentId="13430" CreationDate="2015-03-24T13:30:12.190" Score="17" Body="&lt;p&gt;I believe this question is answered &lt;a href=&quot;https://aviation.stackexchange.com/questions/1814/which-engine-is-more-efficient-between-turboprop-vs-jet&quot;&gt;here&lt;/a&gt; and a nice comparison can be found &lt;a href=&quot;http://airinsight.com/2011/08/19/jet-vs-turboprop-a-debate-that-dates-from-the-early-1950s/#.VRF2C47F8Ro&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; but the short answer is efficiency. If memory serves jets gain their efficiency at high altitude moving fast and generally over a long distance. If you are going on a short hop turbo props will be more efficient overall. This chart provides a nice outline of the difference in efficiency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qvOLW.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for large piston pounders I am not sure of the efficiency but I would think the cost of keeping one running is high simply based on their age (no one is really making big piston planes anymore as far as i know). History channel has a nice show &quot;Ice Pilots NWT&quot; about a freight/passenger airline that still runs DC-3's and the general issues they have with them many of which is related to finding parts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said not all airlines had the money to jump right into jets when they came out. Lots of turbo-props are still flown simply because there is no reason to replace them. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-03-25T19:51:34.137" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13433" PostTypeId="2" ParentId="13430" CreationDate="2015-03-24T14:10:49.513" Score="12" Body="&lt;p&gt;This question devolves into two related questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) When buying or leasing the plane, what is the most economical plane for this route (and other routes that the plane may have to fly) at your airline.  One size does not fit all, what is optimal for one leg may be much less desirable for the next.  &quot;Economical&quot; includes capital costs, maintenance costs, operating costs, and down-time costs.  Are your maintenance facilities proficient on this type plane?  Are your pilots cross trained on this new aircraft?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Years later your short term choices are limited to the aircraft in your inventory.  What is the best available aircraft for this flight?  For the entire route? Can this plane fit into the runways at the required airports?  Can the aircraft make the trip without stopping for fuel?  How many passengers have booked this flight in advance? the questions that need to be considered are many.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer:  &quot;Oh, I think I'll fly the Turboprop today&quot; is not how it works.  It is a long involved decision considering multiple factors all leading to what user16230 calls efficiency and what I will call profit.  Same thing measured differently.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="11" LastEditDate="2015-03-25T19:15:46.853" LastActivityDate="2015-03-25T19:15:46.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13434" PostTypeId="2" ParentId="13426" CreationDate="2015-03-24T14:19:37.030" Score="5" Body="&lt;p&gt;It can happen.  The last line of defense is &quot;See and Avoid&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://articles.latimes.com/1987-09-04/news/mn-4004_1_delta-flight&quot; rel=&quot;noreferrer&quot;&gt;Associated Press: September 04, 1987&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;WASHINGTON — The Federal Aviation Administration said today that it is&#xA;  working on new navigation procedures for ocean flights in the wake of&#xA;  a July incident in which a Delta Air Lines jetliner came within 30&#xA;  feet of colliding with another jet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Investigators say the Delta airliner, flying 60 miles off course, came&#xA;  much closer to colliding with another jet than was previously thought.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Delta plane was within Canadian air traffic control when the&#xA;  near-collision occurred, and the Canadian Aviation Safety Board said&#xA;  Thursday that it wants immediate changes in that nation's airline&#xA;  safety rules to reduce the chance of additional incidents.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, the FAA said today that it already has a program under way to&#xA;  improve navigation procedures used by American aircraft on&#xA;  transatlantic and transpacific routes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="291" LastEditorUserId="65" LastEditDate="2015-03-24T14:25:29.210" LastActivityDate="2015-03-24T14:25:29.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13436" PostTypeId="2" ParentId="13421" CreationDate="2015-03-24T16:10:37.637" Score="9" Body="&lt;p&gt;The answer to your question is in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.205&quot;&gt;FAR 91.205&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;91.205(b) - &lt;em&gt;Visual-flight rules (day)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(11) For small civil airplanes &lt;strong&gt;certificated after March 11, 1996&lt;/strong&gt;, in accordance with part 23 of this chapter, an approved aviation red or aviation white anticollision light system. In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and 91.205(c) - &lt;em&gt;Visual-flight rules (night)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) An approved aviation red or aviation white anticollision light system &lt;strong&gt;on all U.S.-registered civil aircraft&lt;/strong&gt;.  &lt;em&gt;(it goes on to talk about color, which I've cut out)&lt;/em&gt; In the event of failure of any light of the anticollision light system, operations with the aircraft may be continued to a stop where repairs or replacement can be made.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So as you surmised in your question, a 1967 Cherokee is required to have an operating anti-collision light for Night-VFR operations (because the night anti-collision requirement is retroactive and doesn't care about certification date), but not for day Day-VFR operations (because it was certificated prior to 1996).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you HAVE an anti-collision light it is required to be operating subject to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.2.91_1213&amp;amp;rgn=div8&quot;&gt;FAR 91.213&lt;/a&gt;. The relevant part of that regulation says that you can take off with inoperative equipment provided that equipment &lt;em&gt;is not&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(i) Part of the VFR-day type certification instruments and equipment prescribed in the applicable airworthiness regulations under which the aircraft was type certificated  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You're OK for Day VFR because CAR3 (and FAR 23 prior to 1996) didn't require an anti-collision light for daytime operations.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(ii) Indicated as required on the aircraft's equipment list, or on the Kinds of Operations Equipment List for the kind of flight operation being conducted;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Your Cherokee predates the concept of a Kinds of Operations Equipment List in small aircraft by several decades, so your reference is 91.205.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) Required by §91.205 or any other rule of this part for the specific kind of flight operation being conducted; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the kind of flight is &quot;Day VFR&quot; the anti-collision light is not required by 91.205, but if you want to fly at night it &lt;em&gt;is&lt;/em&gt; required (as we determined previously from 91.205).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iv) Required to be operational by an airworthiness directive&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No such Airworthiness Directive exists for anti-collision lights on the PA-28 family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;…so per 91.213 you can placard the beacon switch INOP and &quot;deactivate&quot; the anti-collision light (simply putting a bit of masking tape on the switch holding it in the off position &amp;amp; writing INOP on that is generally considered adequate) and fly in Day-VFR conditions (ideally to an airport where you can get a replacement lamp for your beacon).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the fact that your beacon was optional equipment doesn't enter into the decision tree for 91.213: Any installed equipment gets evaluated according to this regulation. As an example my (1965) Cherokee has both a tail beacon (originally installed by Piper) and a belly strobe (added by someone over the years): if either is inoperative it needs to be &quot;deactivated and placarded&quot; appropriately.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-24T16:10:37.637" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13437" PostTypeId="2" ParentId="13422" CreationDate="2015-03-24T16:23:19.377" Score="25" Body="&lt;p&gt;From what I know, airline transport pilots do not get large chunks of free time on a typical long-haul flight which you described. They may get small intervals of free time (e.g. 10-20 minutes), but for sure, not hours. They do need to constantly monitor if the airplane is flying on the correct course, on the assigned altitude, remaining fuel amounts and several other tasks, &lt;em&gt;even when auto-pilot is engaged.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So what do pilots do when they are not flying at all?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Primarily, it depends on company policies. Delta &lt;a href=&quot;http://www.cnn.com/2009/TRAVEL/10/28/pilots.cockpit/index.html?eref=rss_us&quot;&gt;does not allow pilots&lt;/a&gt; to do anything not related to flying the airplane:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;You can't read a novel, but you could read a manual about procedures&#xA;  or about the airplane,&quot; ... &quot;You can't read a newspaper. You can't use&#xA;  a laptop. That's strictly prohibited.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But generally speaking, pilots engage in causal chats between themselves and flight attendants (when they visit the cockpit)&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there are more than two pilots, one is generally allowed to get some rest. They can also browse through magazines or read some books or flight-related material, but mostly stay alert and available. Some will study for an upcoming proficiency or rating. One of the two pilots can go to the bathroom too. &lt;a href=&quot;http://www.cnn.com/2015/01/30/travel/feat-delta-captain-lockout/&quot;&gt;Getting locked out depends on pure luck.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in a nutshell, there are several different activities/tasks pilots will engage into, each different for a particular flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a funny little anecdote I recently read, which fits this discussion very well:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Murphy's law grants you a heap of emergencies once you start feeling&#xA;  bored in the cockpit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;em&gt;As a ordinary passenger, I don't visit the cockpit, but I have noticed a few times what the flight attendants do. When they have free time, they have many things to talk about between themselves. Sometimes, they engage in small talk with passengers. They check their schedule and flights for the remainder of the day. Although the duties of flight attendants and pilots are entirely different, there are a bunch of activities which require their attention, and they can pass the time without getting too bored.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-07-02T15:02:57.517" LastActivityDate="2015-07-02T15:02:57.517" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13438" PostTypeId="1" AcceptedAnswerId="13442" CreationDate="2015-03-24T18:38:00.910" Score="3" ViewCount="1375" Body="&lt;p&gt;&lt;strong&gt;Spoilers for the Pilot episode of Scorpion&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote class=&quot;spoiler&quot;&gt;&#xA;  &lt;p&gt; In the Pilot episode for the TV series &lt;em&gt;Scorpion&lt;/em&gt;, all major control towers in the greater LAX area are taken out because the firmware is malfunctioning and our heroes need to get a proper version active again, while the airborne planes could not be contacted through any method. They first try to recover a backup version of the software from a datacenter, but that fails. They then contact a salesman on a plane via his antique cellphone and manage to reload the software using a Ferrari and a laptop wired into the plane.&#xA; One of the major plot points was that, because the software was malfunctioning, none of the planes could land safely, even though one of the planes could safely buzz the tower and even get close enough to the ground to make a wire connection to the ground. If they could fly so low, why can't they just land it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So can a plane land during a complete control tower malfunction? And what is the general SOP in case of malfunctions? I've read both &lt;a href=&quot;https://aviation.stackexchange.com/questions/13426/how-realistic-is-the-aviation-crisis-in-the-recent-spider-man-movie&quot;&gt;How realistic is the aviation crisis in the recent Spider-Man movie?&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/7599/what-happens-when-the-airport-shuts-down&quot;&gt;What happens to incoming flights when the airport shuts down&lt;/a&gt;, but part of the plot was that every airport in the greater LAX area got the problematic malware at the same time, so it's possible that many of those planes had their alternate destination airport also in trouble.&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-24T23:49:36.633" Title="Can planes still land during a regionally-diverse ATC malfunction?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13439" PostTypeId="1" CreationDate="2015-03-24T18:47:16.363" Score="11" ViewCount="3102" Body="&lt;p&gt;When flying a circuit, the leg after &lt;em&gt;downwind&lt;/em&gt; and before &lt;em&gt;final&lt;/em&gt; is called &lt;em&gt;base&lt;/em&gt;. Where does this name come from?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2021-04-04T09:42:52.517" Title="Why is it called &quot;base&quot; leg?" Tags="&lt;terminology&gt;&lt;traffic-pattern&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13440" PostTypeId="2" ParentId="13439" CreationDate="2015-03-24T19:14:43.950" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airfield_traffic_pattern&quot; rel=&quot;nofollow&quot;&gt;Traffic pattern (circuit)&lt;/a&gt; phases are named so that they do not cause confusion&lt;sup&gt;1&lt;/sup&gt;. I think of it as the leg which is taking me towards my landing/home base. &lt;em&gt;(It is just a memory aid.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;http://www.challengers101.com/Pattern1.html&quot; rel=&quot;nofollow&quot;&gt;the following reason&lt;/a&gt; is the best one which I found:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This leg represents the foundation for the final approach, that is,&#xA;  the base from which the final approach is initiated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another reason is &lt;a href=&quot;http://smartflighttraining.com/fundamentals-airport-traffic-patterns&quot; rel=&quot;nofollow&quot;&gt;as follows&lt;/a&gt;, although it is similar to a memory aid:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... base leg is called “base” because it is really the foundation of&#xA;  your landing (the “base” of a house is its foundation – and if it&#xA;  isn’t right, the whole house will never be right) – if the base leg&#xA;  isn’t right, your whole landing will suffer for it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: Although, &lt;em&gt;upwind leg&lt;/em&gt;, &lt;em&gt;crosswind leg&lt;/em&gt; and &lt;em&gt;downwind leg&lt;/em&gt; relates with the wind direction too. But if wind is perpendicular to the runway, downwind leg is not actually downwind, but it is still called the downwind leg.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-24T19:14:43.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13441" PostTypeId="2" ParentId="13438" CreationDate="2015-03-24T19:45:40.700" Score="2" Body="&lt;p&gt;Yes it can(and that episode no matter how cool a show was full of simply non-accurate things). If your question is simply about a tower malfunction look for a minute at the fact that many airports (granted generally smaller ones) in this country do not have a control tower. They are thus called uncontrolled fields. You can find some nice guidance &lt;a href=&quot;http://flighttraining.aopa.org/pdfs/SA08_Nontowered_Airport_Ops.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; on their procedures. Keep in mind these procedures are for uncontrolled fields there may be a different protocol for a large field losing its tower that I don't know about. On that note there are some fields that have towers that are not always operational be it seasonally or based on the hour of the day. In that event you can still land at the airport using uncontrolled procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now keeping that in mind there is an aircraft density issue at a place like LAX. Generally speaking uncontrolled fields are smaller and often less busy than a place like LAX so while it may not be &quot;safe&quot; there is nothing that would stop the planes from landing. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-24T19:45:40.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13442" PostTypeId="2" ParentId="13438" CreationDate="2015-03-24T19:53:00.033" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;During a control tower malfunction, can planes still land?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one tower goes down, the other layers of ATC will still be functioning, and they'll divert the aircraft elsewhere: if LAX goes down, national level ATC would work with the SoCal Tracon (Southern California Terminal Radar Approach Control -- i.e. &quot;Approach&quot;) and perhaps the airline dispatchers to send the airplanes elsewhere: San Diego, Ontario, Long Beach, Burbank.  Those farther out would be diverted elsewhere just to avoid having too many airplanes piled up in one place: land in the Bay Area, or LAS or PHX, for instance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Okay, let's assume that all the towers in the LA Basin are &lt;strong&gt;&lt;em&gt;all&lt;/em&gt;&lt;/strong&gt; down.  And let's assume that SoCal is down too.  And just to make the scenario complete, we'll assume that LA Center has lost all of their radios too.  (This is like the scenario that happened several months ago when Chicago Center lost their radios due to sabotage, except we're assuming LOTS of facilities all have the same problem at the same time.  Straining the limits of &quot;willing suspension of disbelief&quot; pretty hard here, but let's do it to make the point.)  What happens?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots talk to each other on the usual frequencies and land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are plenty of uncontrolled airports out there, and they function just fine with pilots using what's known as CTAF -- the Common Traffic Advisory Frequency, where everybody broadcasts their position &amp;amp; intentions.  &quot;Whozit Traffic, Cessna 1234A, left base, touch &amp;amp; go Whozit.&quot;  &quot;Whozit Traffic, Piper 9876B, left downwind, full stop Whozit.&quot;  Based on those transmissions, you can build a good picture of who's where, who's closest to me &amp;amp; where I need to be looking to find him, and what (if anything) I need to do differently to not get too close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And nobody needs ANY assistance from the tower in order to put the aircraft safely on the runway, stop, and exit.  We talk to them to keep the flow of traffic neat &amp;amp; orderly (they can be more efficient than just working it out on our own -- particularly when you start alternating departures with arrivals), but they have &lt;strong&gt;&lt;em&gt;zero&lt;/em&gt;&lt;/strong&gt; role in the actual act of landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in the scenario posited above where every ATC radio in all of the southern half of the state of California has failed, there would be complications, particularly if there was weather involved.  (See Die Hard 2, where weather had shut down EVERY airport in North America, apparently, save one, and the bad guys had shut down the ILS to that airport... we're well beyond &quot;willing suspension of disbelief&quot; there.)  But you'd also have a couple of things in your favor: no departures, and the runways normally used FOR departures would be available for landings as well.  Also, the goal is no longer a smooth &amp;amp; efficient flow of aircraft in &amp;amp; out; it's simply to get everybody on the ground safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be a mess once you got on the ground &amp;amp; wanted to get to a gate?  Sure.  Visions of gridlocked LAX are easy enough to imagine.  But could everybody get on the ground safely?  &lt;strong&gt;Absolutely.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-24T19:53:00.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13443" PostTypeId="2" ParentId="13426" CreationDate="2015-03-24T20:00:10.630" Score="4" Body="&lt;p&gt;ATC facilities all have backup power generators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And aircraft have TCAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if one ATC facility goes down, others are out there to assume control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chicago Center went down several months ago due to sabotage (a fire in a closet with much of the network/switching equipment), and while it wasn't an efficient operation for some time, the other layers of ATC picked up the load and things kept working.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-24T20:00:10.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13444" PostTypeId="2" ParentId="13438" CreationDate="2015-03-24T20:09:17.263" Score="10" Body="&lt;p&gt;Not all airport actually have a control tower, so it is very much possible to land without any tower assistance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On major airports however it would likely become chaos in very short time. In order to be able to communicate to aircraft in case of a radio failure, ATC control towers are equipped with light guns. These bright focussed lights allow an Air Traffic Controller to communicate instructions to aircraft both on the ground and in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p6BFh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8pOeC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-24T20:25:37.420" LastActivityDate="2015-03-24T20:25:37.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13445" PostTypeId="2" ParentId="153" CreationDate="2015-03-24T20:21:44.970" Score="1" Body="&lt;p&gt;I can't trace this back to the CFR's, but I'll tell you that our OpSpecs and MEL's require that the autopilot DOES have to be engaged (and thus, operative) when in level flight in RVSM airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is APPROVED to go into RVSM airspace based on the equipment that it has, with an assumption that it all works.  That approval process happens outside of anything that the actual line pilots ever see.  We have our operating manuals, which are driven by Part 121 and our carrier's OpSpecs, and they're pretty clear on the point.  Our MEL likewise says that RVSM operations aren't allowed if both autopilots are deferred, and I strongly suspect that everybody else's manuals say exactly the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the exception to all this is that ATC &lt;em&gt;could&lt;/em&gt; clear you into the airspace anyway and provide 2000' of separation from everybody else, and at 0300L that might actually work.  And I've heard a few military jets that aren't RVSM approved (old altimeter systems, I think) get that treatment as well.  So the general answer to the question is &quot;no,&quot; although the precise answer is &quot;yes, if...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But generally, no, you need the autopilot engaged while in level flight in RVSM airspace.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-24T20:21:44.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13446" PostTypeId="2" ParentId="13340" CreationDate="2015-03-24T21:02:12.517" Score="3" Body="&lt;p&gt;Copters fly SVFR more often than fixed-wing for a number of reasons: SVFR minimums are lower (see 91.157), can be done at night, and are not subject to the &quot;NO SVFR&quot; of Part 91 Appendix D Section 3 that prohibits SVFR at large Class B airports. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, Copter instrument approaches can terminate at the MAP with an SVFR clearance to the airport. Such approaches may even be noted on the flight plan. For example, the MAP for &lt;a href=&quot;http://flightaware.com/resources/airport/JFK/IAP/COPTER+RNAV+(GPS)+028/pdf&quot; rel=&quot;nofollow&quot;&gt;JFK COPTER RNAV (GPS) 028°&lt;/a&gt;&lt;sup&gt;(PDF)&lt;/sup&gt; depicts various VFR routes to the NYC heliports. These can be flown SVFR. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="19" LastEditDate="2016-07-05T06:45:48.333" LastActivityDate="2016-07-05T06:45:48.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13447" PostTypeId="1" AcceptedAnswerId="13476" CreationDate="2015-03-24T21:56:20.320" Score="20" ViewCount="6783" Body="&lt;p&gt;At least in airliners, the truly critical computers are redundant. Typically three identical copies of the autopilot computers run in parallel and compare results; if one computer disagrees with the other two, its output is ignored. The system allows some processors to be faulty while maintaining the operation of the overall system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why? I've never heard of microprocessors suddenly failing. Sure, there could be manufacturing errors, but those would have been caught at the factory. Perhaps the program (and its proof) is wrong, but it would be wrong in the same way across the processors. Similarly, bad input would cause bad output across all three computers. What kind of errors does this redundancy protect against? Do microprocessors sometimes just do math wrong?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a microprocessor is overheated or overloaded and spontaneously fails, I would expect it to stop doing anything and produce no output. To deal with this kind of failure, you'd want to have a backup processor, but you wouldn't need to compare the outputs of three computers—any output produced would be assumed correct, so you'd be happy to directly use the output of any processor that was producing output. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: The answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3416/what-is-the-purpose-of-multiple-autopilots?rq=1&quot;&gt;What is the purpose of multiple autopilots?&lt;/a&gt; simply says &quot;redundancy&quot; before going into how this is achieved.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2017-10-07T17:27:45.523" Title="Why are critical flight computers redundant?" Tags="&lt;avionics&gt;&lt;autopilot&gt;" AnswerCount="12" CommentCount="18" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13448" PostTypeId="2" ParentId="8318" CreationDate="2015-03-24T22:51:32.697" Score="-1" Body="&lt;p&gt;Prop planes have a longer glide ratio. (they fly farther when the engine quits. ) My father would have said jets have the glide path of a rock, the slower they go, the faster they come down!  Jets are also much more complex and sometimes simple is safer to maintain as well as fly.&lt;/p&gt;&#xA;" OwnerUserId="7712" LastActivityDate="2015-03-24T22:51:32.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13450" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T00:36:36.423" Score="2" Body="&lt;p&gt;If we look at this from a strictly engineering standpoint, microprocessors like anything have a cycle lifetime. Generally speaking it's very long, and the PC you are posting this from most likely will be out dated long before it hits is cycle life time. Although a microprocessor has no moving parts it does take input from various sensors. I can only assume that the inputs are fused in some way, but that does not mean that a spikes are completely eliminated and isolated if they do occur. For what it's worth, even relatively small surges will fry a microprocessor. Keeping that in mind, to err on the side of caution multiple systems are used. With the ever shrinking size of technology it has gotten easier and cheaper to carry a spare so from a sales standpoint the peace of mind is there. Again it's better to have it and not use it than to not have it when you need it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To directly address your question, I have been around microprocessors, micro-controllers and the like for a long time. In that time I have had maybe two or three fail spontaneously, usually related to heat. In a plane this may not seem like an issue but actually extreme cold can cause issues as well as extreme heat when it comes to electronics. That being said I have toasted countless units by hitting them with overloaded inputs. Let's say your plane got hit by lighting (I know that modern airlines are protected against this) but for arguments sake let's say a ground was bad: this would easily toast a unit.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: It is more common for memory chips/drives to fail these days. This is something you may never know as most modern computers can deal with dead memory be it in the disk or in system memory.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="753" LastEditDate="2015-03-25T09:47:03.157" LastActivityDate="2015-03-25T09:47:03.157" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13452" PostTypeId="2" ParentId="13428" CreationDate="2015-03-25T02:16:47.900" Score="15" Body="&lt;p&gt;While DeltaLima's answer is very good, it is also due to Air Traffic Control limitations-- you want to spread out where the traffic is across the whole airspace, so routes may dogleg left or right at one point to try to keep traffic flow good (also helps separate aircraft going in opposite directions, but altitude does that too).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the arrival patterns into certain airports have defined entry points and are designed to line up the plane in a certain way for the airport, and flights may have to go slightly out of their way to join the arrival.&lt;/p&gt;&#xA;" OwnerUserId="311" LastActivityDate="2015-03-25T02:16:47.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13453" PostTypeId="1" AcceptedAnswerId="13501" CreationDate="2015-03-25T02:25:23.767" Score="13" ViewCount="6572" Body="&lt;p&gt;&lt;em&gt;Bernoulli's Principle&lt;/em&gt; states that as a fluid speed increases, its pressure decreases, and vice versa.  Air flowing over the wing of an aircraft flows faster than its neighboring air flowing under the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;But &lt;em&gt;how much&lt;/em&gt; faster?&lt;/strong&gt;  Using the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400#Specifications&quot;&gt;cruise conditions listed for a Boeing 747-400&lt;/a&gt; &amp;ndash; airspeed Mach 0.85 (567 mph, 493 knots, 912 km/h) flying at 35,000 ft &amp;ndash; what are the corresponding maximum and minimum speeds of the airflow over the wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purposes of the calculation, assume standard atmospheric conditions for an EAS of 273 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How much does this depend on the shape of the airfoil (or: does this translate to general aviation as well)?&lt;/li&gt;&#xA;&lt;li&gt;Does changing the angle of attack (without stalling) affect the airspeed/pressure differential?  If so, by how much?&lt;/li&gt;&#xA;&lt;li&gt;Typically, where on the wing (inboard to outboard) is the most Bernoulli-derived lift generated (i.e. due to airspeed/pressure differential)?  Or does this vary greatly with wing design?&lt;/li&gt;&#xA;&lt;li&gt;Where on the airfoil (leading edge to trailing edge) is the region of highest and lowest pressures (and thus, the slowest- and fastest-moving air)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="7568" LastEditDate="2015-03-25T14:37:05.713" LastActivityDate="2015-05-07T06:03:13.140" Title="What is the actual air speed over and under a wing due to Bernoulli's Principle?" Tags="&lt;airspeed&gt;&lt;lift&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13455" PostTypeId="2" ParentId="13453" CreationDate="2015-03-25T03:36:43.160" Score="4" Body="&lt;p&gt;Wishing I had my copy of Basic Aerodynamics handy to provide some more detailed references and numerical examples (may come back later to add more detail), but here goes the highly abbreviated version.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Airfoil shape is absolutely critical in determing the distribution of lift (and therefore air pressure differential between the two sides of the wing) and this holds true for literally anything that makes use of them. The exact specifics as to how much this varies differ from one airfoil to the other, but you should be able to just look up the airfoils you're interested in and compare their coefficients of lift, one of the variables in the generation of aerodynamic force (i.e. horizontal lift and induced drag), at various alphas (a.k.a. angle of attack, angle of incidence).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The coefficient of lift is indeed determined by the angle of attack. The greater the angle of attack, the greater the coefficient of lift, right up until the point where airflow separates from the wing and you enter a stall. The end result is that, for a given airfoil and &lt;strong&gt;constant&lt;/strong&gt; airspeed, the higher the angle of attack, the more lift your wing will generate, and the greater the air pressure differential.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A very interesting question and the answer is, it depends. For a constant camber airfoil (think your basic Hershey-bar style wing), you should be able to get more lift being generated closer to the wing roots. This happens due to the fact the airflow tends to &quot;slip&quot; around the wing edges due to the fact that we do not have infinite span wings and the higher pressure air underneath the wing tries to fill the lower-pressure areas on top and has an outlet to do so where the wing ends. The end result of this phenomenon is known as a wingtip vortice and one of the effects is that the aerodynamic force vector usually has a somewhat different direction at the wing edges vs. the tip, usually leading to less vertical lift being generated their as opposed to the wing root. Other things to keep in mind, many modern manufacturers will use variable-camber designs today to build wings that stall at the wing root first in order to ensure aileron control as far into the stall as possible. Recommended further reading on this topic: wingtip vortices, wake turbulence, winglets, Spitfire wing&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For most subsonic airfoils, the center of pressure will occur quite close to the leading edge. Again, this depends on the wing design itself, which is dependent on aircraft role and requirements. Aircraft designed to fly slowly will typically have relatively &quot;fat&quot; wings with a pronounced camber close to the leading edge. Aircraft design to fly faster will seek to reduce frontal area and will have their thickest camber set farther back. Supersonic airfoils generally have a vaguely diamond-shaped profile owing to the need to keep the leading edge very sharp and the frontal area minimized.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If I might suggest, if this is something you're curious about, look into picking up an introductory text on aerodynamics. The topic is truly fascinating and the answers to your questions can run very deep indeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the meantime, hope this helps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Follow-up&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@erich @FreeMan I've been doing some thinking about the 747 question and I think it's worth delving into some of the underpinnings to clarify a few things. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: My expertise here is as a pilot rather than an aero engineer (big, big difference in the depth of study of aerodynamics), so if any mistakes follow, that's why.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to remember about an aircraft in flight is that it's not so much air &quot;flowing&quot; over the wing, as the aircraft &quot;flowing&quot; through the air. We often illustrate air moving over the wing because this is how it works in wind tunnels and, as an added benefit, it simplifies things when introducing this topic to new students. We often use the term &quot;Relative Wind&quot; to refer to this phenomena.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such, it is important to remember that when the aircraft moves through the air, it displaces air and pushes it above and below the wing. To further simplify our discussion, let us assume a positively-cambered wing at 0 alpha. What will happen in this situation is that the surface area on the top of the wing, being greater than the surface area below the wing, will have fewer air particles per unit of area leading to lower pressure on the top of the wing than the bottom, as air density is relatively constant around the aircraft. This pressure differential results in a force, whose vertical component counteracts the aircraft's weight, resulting in level flight. Extrapolate from here for climbs, descents, banking turns, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Digression: you may point out that if this is the case, how come airplanes don't just sort of float away when they're on the ground, seeing how the wing area differential still holds. The intuitive reason for that is that unless the aircraft is moving and &quot;disturbing&quot; the air around it, air particles will be free to float around the wing and fill any low pressure areas until the pressures equalize.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going back to our 744, what you would really be interested then is to actually calculate pressure differentials and, working from there, calculate &quot;speed&quot; differentials (keeping in mind that you would actually be calculating more of an &quot;average speed&quot;, as different parts of the wing will generate different amounts of force). Someone else will have to do that math however, as I can't seem to find the necessary technical data. Also, in case you're wondering, yes, the fuselage also generates a certain amount of lift, while the tailplane horizontal stabilizers generate a aerodynamic force downwards (think &quot;negative lift&quot;). Have fun digging :) &lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-03-25T17:34:05.393" LastActivityDate="2015-03-25T17:34:05.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13457" PostTypeId="2" ParentId="7662" CreationDate="2015-03-25T04:50:53.553" Score="2" Body="&lt;p&gt;In the USA, this is defined in the FAA's &lt;strong&gt;Air Traffic Organization Policy&lt;/strong&gt;, &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap2_section_9.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Section 2-9-1&lt;/a&gt;. According to that source, ATC must:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;(a)&lt;/strong&gt; Identify each ATIS message by a phonetic letter code word at both&#xA;  the beginning and the end of the message. Automated systems will have&#xA;  the phonetic letter code automatically appended. Exceptions may be&#xA;  made where omissions are required because of special programs or&#xA;  equipment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; Each alphabet letter phonetic word must be used sequentially, except as authorized in subpara a2, beginning with “Alpha,” ending&#xA;  with “Zulu,” and repeated without regard to the beginning of a new&#xA;  day. Identify the first resumed broadcast message with “Alpha” or the&#xA;  first assigned alphabet letter word in the event of a broadcast&#xA;  interruption of more than 12 hours.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="995" LastEditorUserId="1696" LastEditDate="2019-10-28T16:11:20.320" LastActivityDate="2019-10-28T16:11:20.320" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13458" PostTypeId="1" AcceptedAnswerId="13468" CreationDate="2015-03-25T05:05:16.280" Score="4" ViewCount="7106" Body="&lt;p&gt;According to Section &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0209.html#IbC2daatc&quot; rel=&quot;nofollow&quot;&gt;2-9-1-a&lt;/a&gt; of the FAA's Air Traffic Organization Policy, a phonetic letter is assigned to each tower-issued ATIS update.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This information is available on the ATIS VHF frequency for an airport, or via a phone call to a designated ATIS number for the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a passing reference &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service#Technical_background&quot; rel=&quot;nofollow&quot;&gt;on the Wikipedia page&lt;/a&gt; to ATIS being available electronically via a service named &quot;D-ATIS&quot;, although I've never heard of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd love to be able to view this information electronically, rather than having to get my VHF handheld, or the plane's radio going and tune it in before flight. The voice system is frequently engaged. If it was available via the internet, it'd be super-easy to access.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a means accessing the ATIS - including the identifier - for a given airport in electronic form via the internet? If so, how?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: I know it's possible to get METAR reports, but they are typically automatically generated, not manually adjusted by the tower (as ATIS sometimes is), and don't include the phonetic letter designation issued by the tower and required for initial tower contact.&lt;/p&gt;&#xA;" OwnerUserId="995" LastActivityDate="2015-03-26T04:31:06.150" Title="Is ATIS information - including identifier - available on the internet?" Tags="&lt;usa&gt;&lt;atis&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13459" PostTypeId="1" AcceptedAnswerId="13473" CreationDate="2015-03-25T05:27:15.103" Score="11" ViewCount="2754" Body="&lt;p&gt;By all reports, &lt;a href=&quot;http://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;noreferrer&quot;&gt;ADS-B&lt;/a&gt; is the future of air navigation and ATC. In the simplest definition, ADS-B is aircraft self-reporting GPS position to benefit everyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this secure? Seems like someone could simply broadcast a false position for any number of nefarious purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe I am missing something obvious, but I have yet to see an explanation of ADS-B from a security perspective.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-03-26T05:52:16.497" LastActivityDate="2018-05-20T11:23:07.197" Title="How can ADS-B be secure when it is based on self-reporting?" Tags="&lt;air-traffic-control&gt;&lt;navigation&gt;&lt;security&gt;&lt;ads-b&gt;" AnswerCount="5" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13460" PostTypeId="1" AcceptedAnswerId="13464" CreationDate="2015-03-25T05:33:43.160" Score="33" ViewCount="10937" Body="&lt;p&gt;I've observed helicopters being used often&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;in the military&lt;/li&gt;&#xA;&lt;li&gt;for medical flights&lt;/li&gt;&#xA;&lt;li&gt;for other special use purposes, such as sightseeing and news reporting&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why aren't there any commercial passenger transport helicopter flights? Or are there any examples of this? Are airplanes simply that much more efficient?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2016-10-01T22:53:26.470" Title="Why aren't there more passenger helicopters?" Tags="&lt;commercial-aviation&gt;&lt;helicopter&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13461" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T05:37:17.793" Score="-1" Body="&lt;p&gt;Because, despite the theory being good, the reality is that not all computer components are equal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A specific example from the early 90s: Intel produced the 486/33 CPU (it was quite cutting edge and blazingly fast for the day). Most left the factory just fine, but some had an esoteric bug in the FPU that would generate incorrect answers. The magazines of the day were filled with calculations you could put into your spreadsheet that would produce X if your CPU was good, or Y if it had the bug.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your plane happens to be running with one of the faulty CPUs in it, and just the right set of data happens to be collected and fed into any of the flight control programs and runs into this FPU bug, you'll be happy that the other two CPUs calculated the correct value and kicked the errant one out of the loop.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-03-25T05:37:17.793" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13462" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T05:47:27.640" Score="28" Body="&lt;p&gt;As other answer pointed out: A CPU can fail. Either partially (giving erroneous answers), or totally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover all computer are subject to cosmic radiations that can once in a while flip a bit in memory (in addition to other sources of error like short circuit, ...). That's why scientific experiments and long running servers use &lt;a href=&quot;http://en.wikipedia.org/wiki/ECC_memory&quot; rel=&quot;noreferrer&quot;&gt;ECC&lt;/a&gt; memory.&#xA;Spaceships also use specific &lt;a href=&quot;http://en.wikipedia.org/wiki/Radiation_hardening&quot; rel=&quot;noreferrer&quot;&gt;hardened CPUs&lt;/a&gt; to limit this effect as they are less shielded from such interferences.&#xA;Planes fly at high altitudes and are subject to more of this interferences than your earth-bound computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the event of this happening is very uncommon (but not unheard of), you MUST ensure that the results are 100% accurate.&#xA;One bit flipped could change the behavior of your plane in unpredictable ways, like inverting the controls, inverting the flight envelop protection law, ...&lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="3386" LastEditDate="2017-06-05T05:14:45.597" LastActivityDate="2017-06-05T05:14:45.597" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13463" PostTypeId="1" CreationDate="2015-03-25T06:02:59.427" Score="7" ViewCount="565" Body="&lt;p&gt;(Note &lt;a href=&quot;https://aviation.stackexchange.com/questions/11853/canonical-list-of-sources-for-worldwide-digital-ga-vfr-maps&quot;&gt;this question&lt;/a&gt; asks about VFR charts.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the U.S, I can get IFR navigation charts from &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/ifr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronav&lt;/a&gt; or &lt;a href=&quot;http://ww1.jeppesen.com/personal-solutions/aviation/ifr-charts.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jeppesen&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do IFR charts exist worldwide? If so, where can I go for charts of other countries? (A list would be nice since there probably isn't one canonical source?). If not, what are the alternatives?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-12-06T13:20:10.187" Title="Where can I get IFR charts for throughout the world?" Tags="&lt;instrument-flight-rules&gt;&lt;navigation&gt;&lt;aeronautical-charts&gt;&lt;ifr-navigation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13464" PostTypeId="2" ParentId="13460" CreationDate="2015-03-25T06:49:12.730" Score="42" Body="&lt;p&gt;Airplanes are much more efficient, much faster and scale better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters are limited to around 150 knots because when flying forward the tip of the advancing blade must not exceed the speed of sound while the retreating blade must still move aft fast enough to produce lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters are also difficult to make large, because for efficiency the rotor disk needs to be large, but the diameter is again limited by the tip speed having to remain subsonic. And the material requirements to make the blades strong enough without making them too large to keep drag low.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="7779" LastEditDate="2015-03-25T12:52:24.383" LastActivityDate="2015-03-25T12:52:24.383" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="13466" PostTypeId="2" ParentId="13460" CreationDate="2015-03-25T07:06:28.917" Score="21" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/13464/572&quot;&gt;Jan Hudec's answer&lt;/a&gt; has already detailed why helicopters are not widely used for mass transportation or have been scaled up to ferry passengers more often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The few exceptions exist where landing space is limited and the helicopter's maneuverability is more advantageous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Offshore Oil &amp;amp; Gas Rigs&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aWPCA.jpg&quot; alt=&quot;Kittiwake landing&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://wn.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.wn.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where transport by ship is not fast enough or not possible due to heavy swell, the use of helicopters allows quick access to the offshore platforms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;New York Helicopter Taxi&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/W5Bce.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.americanbestgetaways.com/usa_city_new_york_helicopter_aeroport_transfers.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.americanbestgetaways.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The New York Helicopter Services allow quick access to the airports around New York for business travelers who would otherwise take more time to arrive in Manhattan.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-03-25T13:59:21.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13467" PostTypeId="2" ParentId="13463" CreationDate="2015-03-25T07:14:38.300" Score="6" Body="&lt;p&gt;The primary source for every country would be the countries' &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeronautical_Information_Publication&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Publication&lt;/a&gt; (AIP). In some cases the AIP is freely accessible, printed copies can be directly obtained from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Civil_Aviation_Authority&quot; rel=&quot;nofollow noreferrer&quot;&gt;Civil Aviation Authority&lt;/a&gt; (CAA) or commercial companies authorized to distribute these, such as Jeppesen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases there will be a joint resource for certain areas, e.g.&#xA;The IFR charts for European countries can be obtained as digital copies from &lt;a href=&quot;http://ead-website.ead-it.com/publicuser/public/pu/login.do&quot; rel=&quot;nofollow noreferrer&quot;&gt;EAD EUROCONTROL&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="14957" LastEditDate="2016-12-06T06:16:03.643" LastActivityDate="2016-12-06T06:16:03.643" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13468" PostTypeId="2" ParentId="13458" CreationDate="2015-03-25T07:19:44.213" Score="5" Body="&lt;p&gt;The short and general answer is: &lt;strong&gt;No&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATIS is only a VHF recording, but even when recorded digitally, it is not available in a text-base form in many cases which would allow being made public on the internet. In the case of D-ATIS, the information can only be obtained using &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;ACARS&lt;/a&gt;, other systems such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Controller%E2%80%93pilot_data_link_communications&quot; rel=&quot;nofollow noreferrer&quot;&gt;CPDLC&lt;/a&gt; require special equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With modern technology and communication, some airports have started to use Twitter to broadcast ATIS, however they should not be used for flight purposes, but are only for entertainment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/556L0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://twitter.com/yssyatis&quot; rel=&quot;nofollow noreferrer&quot;&gt;Twitter&lt;/a&gt; - Account: @yssyatis)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-03-25T13:49:14.337" LastActivityDate="2015-03-25T13:49:14.337" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13469" PostTypeId="2" ParentId="13458" CreationDate="2015-03-25T08:20:33.860" Score="5" Body="&lt;p&gt;In Australia the full ATIS and identifier is available on the internet in text form (along with all the weather and NOTAMs) - but it is only available to pilots. The information is provided by Airservices Australia (which is basically our government-owned version of NATS) through their online service called NAIPS. NAIPS is free but to register you need an Aviation Reference Number issued by CASA, which are only available to pilots or engineers or other important people. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate, here is the ATIS from Sydney (YSSY) from a bit earlier today, they were using identifier K:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;ATIS YSSY K   260229&#xA;  APCH: EXP INDEPENDENT VISUAL APCH.&#xA;        DO NOT PASS THRU, ASSIGNED RWY CL&#xA;  RWY: 34L AND R FOR ARRS AND DEPS&#xA;  OPR INFO: PARL RWY OPS IN PROGRESS.&#xA;            INDEPENDENT DEPS IN PROGRESS&#xA;  WIND: 260/12&#xA;        XW MAX 12&#xA;        DW MAX 3&#xA;+ VIS:&#xA;+ WX: CAVOK&#xA;+ CLD:&#xA;  TMP: 27&#xA;+ QNH: 1015&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2015-03-26T04:31:06.150" LastActivityDate="2015-03-26T04:31:06.150" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13470" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T08:39:24.713" Score="4" Body="&lt;p&gt;Computers fail, spontaneously, all the time. You're not used to that because you've not used many computers. But consider somebody like Google, who runs massive data centres containing thousands of computers. The software that runs Google is designed around the explicit assumption that computers do fail because it happens multiple times per day. Now, an aircraft doesn't contain very many computers but the ones it does contain are safety-critical. So they're duplicated to make sure their failure doesn't cause a problem.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-03-25T08:39:24.713" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13472" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T09:17:44.057" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why are critical flight computers redundant?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Software&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;One point that has been missed is that the redundant systems are often independent designs, especially the software. This guards against design faults (or software bugs) that may otherwise cause problems under rarely occurring combinations of circumstances.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Hardware&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Even if a microprocessor is highly reliable, there are a number of factors that may be relevant&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;aircraft fly at high altitude where the atmosphere provides less protection against &lt;a href=&quot;http://rpd.oxfordjournals.org/content/86/4/337&quot;&gt;cosmic rays&lt;/a&gt;. This not only affects &lt;a href=&quot;http://aircrewhealth.com/Topics/hazards/radiation.htm&quot;&gt;crew health&lt;/a&gt; but has the potential to &lt;a href=&quot;http://spacemath.gsfc.nasa.gov/engineering/3Page6.pdf&quot;&gt;interfere with electronic devices&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Avionics systems are composed of more than just microprocessors, there are surely also other, more failure-prone, devices - such as capacitors. There are innumerable ways electronics can fail, e.g. vibration induced failure of grounding leading to interference on data lines (e.g. from analogue sensors).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I've never heard of microprocessors suddenly failing.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Reliability ≠ Safety&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Many accidents occur without any component “failure”&lt;br&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Caused by equipment operation outside parameters and&#xA;  time limits upon which reliability analyses are based.&lt;/li&gt;&#xA;  &lt;li&gt;Caused by interactions of components all operating&#xA;  according to specification.&lt;/li&gt;&#xA;  &lt;li&gt;Highly reliable components are not necessarily safe&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sup&gt;From &lt;a href=&quot;http://www.jacobsschool.ucsd.edu/GordonCenter/g_leadership/l_summer/docs/saase/tutorial-presentations/NancyLeveson.pdf&quot;&gt;Nancy Leveson, MIT, via UCSD&lt;/a&gt;&lt;/sup&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-03-25T10:37:00.067" LastActivityDate="2015-03-25T10:37:00.067" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13473" PostTypeId="2" ParentId="13459" CreationDate="2015-03-25T09:41:43.707" Score="10" Body="&lt;p&gt;You aren't missing anything obvious, ADS-B spoofing (the sending of faked messages) and tampering (putting incorrect information into a message) is possible as there is no message authentication built into the protocol. The receiving station has no way to check whether messages are fakes. There are some proposed solutions &lt;a href=&quot;http://www.sciencedirect.com/science/article/pii/S1000936114000983&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://www.sbir.gov/sbirsearch/detail/415769&quot;&gt;here&lt;/a&gt;, to my knowledge there has been no decision to change the protocol standard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that even if you add message authentication to the protocol there would still be ways to send faked messages. ADS-B uses GPS, there's no reason you couldn't fake the GPS data being sent to a broadcast unit. The unit would have no way of knowing the GPS data is not genuine, and would send position information thinking it was authentic. So even with authentication and security in the broadcast protocol you still cannot implicitly trust the information sent as potential attackers have access to the actual transmission hardware and systems. This means in order to trust the information you have to validate it using another source.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has been close-lipped about it, they say they have the situation covered but they won't say how. It may be that they feel that the continued use of radar in built-up and secured areas (there's no plans to ditch radar completely in favor of ADS-B) will allow ATC computers to filter out the fakes. Radar is computerized, some smart algorithms would be able to match radar data to ADS-B broadcasts and alert when ADS-B data doesn't match up. An aircraft trying to fly into the Washington DC zone would not be able to use spoofing to get close to a sensitive target for example. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would mean that the areas where spoofing is more likely to be successful would be areas where there is no radar coverage. Yes, someone could mask their aircraft's true location or fake an airplane in these locations, however the benefits of the system would seem to outweigh the potential risks. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-03-25T09:41:43.707" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13476" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T11:54:15.710" Score="30" Body="&lt;p&gt;Failure modes to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Overheating. This changes the chip's timing properties and eventually results in error. This can manifest as single-bit errors in the middle of seemingly normal operation; it will &lt;em&gt;eventually&lt;/em&gt; crash, but may output bad data first.&lt;/li&gt;&#xA;&lt;li&gt;Water damage. Manifests as a parasitic resistance on the board and may cause you to misinterpret bits as high or low. May be leaky housings, condensation, etc.&lt;/li&gt;&#xA;&lt;li&gt;Electromagnetic interference. (The system is supposed to be resistant to this, but it's still worth thinking about).&lt;/li&gt;&#xA;&lt;li&gt;Physical connection problems. Either during construction (soldering faults) or induced afterwards (heat, vibration). Microscopic cracks in boards or joints can pass QA but result in intermittent faults. Again this can lose you a single bit at a time. This is related to the Xbox &quot;red ring of death&quot; issue.&lt;/li&gt;&#xA;&lt;li&gt;Failure of other components. Capacitors are the usual suspect; electrolytic, tantalum, ceramic all have different failure modes. Again this may result in a system that &lt;em&gt;mostly&lt;/em&gt; works but is prone to misinterpreting marginal values or suffers from timing drift.&lt;/li&gt;&#xA;&lt;li&gt;Weird materials science (&lt;a href=&quot;http://en.wikipedia.org/wiki/Gold-aluminium_intermetallic&quot;&gt;&quot;Purple plague&quot;&lt;/a&gt;, tin whiskers due to lead-free solder)&lt;/li&gt;&#xA;&lt;li&gt;Part QA may not be up to the standards you expect (suppliers shipping inferior parts with a bogus &quot;aerospace grade&quot; label). Hard to detect even after it's happened.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's important to recognize that in high-speed digital systems you don't get nice clean &quot;one&quot; and &quot;zero&quot;, you get a series of rising and falling edges that are smeared out by the parasitic capacitance and inductance of the wiring. This is inherently vulnerable to being misinterpreted in marginal electrical conditions.&lt;/p&gt;&#xA;" OwnerUserId="7776" LastActivityDate="2015-03-25T11:54:15.710" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13477" PostTypeId="2" ParentId="13460" CreationDate="2015-03-25T12:17:48.103" Score="3" Body="&lt;p&gt;When I took flying lessons, I looked into a helicopter certification. The rental cost was 2-3 times more than a fixed wing aircraft at the time. I don't know what it costs now, but I assume it's still really expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are passenger helicopters, usually used by corporations or very wealthy individuals. Some companies maintain their own fleet or charter when needed (which is probably cheaper). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One company I worked for early in my career maintained an intra-site fleet of helicopters (if your manager would approve it and the weather held, an hour drive became a 20 minute helicopter ride). I never got to use it because this was one of the first things to go when the company went into decline and needed to cut costs.&lt;/p&gt;&#xA;" OwnerUserId="3837" LastActivityDate="2015-03-25T12:17:48.103" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13479" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T12:51:40.787" Score="2" Body="&lt;p&gt;On specific redundancy, the &lt;strong&gt;installation environment&lt;/strong&gt; of these systems is probably the biggest factor.  Not only are many systems crammed closely together in tight spaces, but airflow is often very limited in there.  Heat is a great destroyer of many a microprocessor.  Airplanes also vibrate, a lot, due to spinning engines, in-flight turbulence, and simply landing.  Poor solder joints and sub-par crimp jobs or a loose connector backshell, and you got a bad connection, or worse, an &lt;em&gt;intermittent&lt;/em&gt; one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On redundancy in general, if you experience a BSOD at work, comparatively it's no big deal.  You might have lost the document you were working on, but that's about it.  If aircraft systems go out, you have a real problem.  It's difficult to achieve, but the redundancy is there because &lt;strong&gt;the lives of hundreds of people are relying upon it&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-26T00:14:52.583" LastActivityDate="2015-03-26T00:14:52.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13480" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T12:51:52.853" Score="11" Body="&lt;p&gt;I know this question has already recieved a handful of answers, but none of them seem to address the issue of why there are three systems in the redundant set, rather than just two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off, as was pointed out by &lt;a href=&quot;https://aviation.stackexchange.com/questions/13447/why-are-critical-flight-computers-redundant/13461?noredirect=1#comment29591_13447&quot;&gt;Simon&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/13447/why-are-critical-flight-computers-redundant/13461?noredirect=1#comment29622_13447&quot;&gt;Jan Hudec&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/a/13472/753&quot;&gt;RedGrittyBrick&lt;/a&gt;, the designs aren't identical at all. Indeed, they are often &lt;strong&gt;completely different&lt;/strong&gt; for very good reason: the probability that any given problem will affect all redundant systems, and &lt;em&gt;especially&lt;/em&gt; affect all redundant systems in the same way, goes from &quot;small&quot; to &quot;utterly miniscule bordering on nonexistent&quot;. Compare &lt;a href=&quot;https://aviation.stackexchange.com/q/44349/753&quot;&gt;How dissimilar are redundant flight control computers?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, as to &lt;strong&gt;why there are three&lt;/strong&gt; systems in each redundant setup. When everything is working fine and the aircraft is in steady flight, for some value and some given set of inputs, all systems report that a correction of 0 (of whatever unit) is needed. At this point there is no problem, and the computers just serve to maintain the present state. Now, one of the component systems fail to do its job properly for any reason, and start reporting that a correction of +50 units is required. That is, the set of responses changes from [0,0,0] to [0,0,+50]. Two systems agree and the third reports something else, so we can likely safely disregard the outlier and go with the two systems that report the same: treat the result as [0,0,incorrect] and ignore the incorrect result while logging technical details and displaying some sort of prominent warning that the systems need to be looked over ASAP. But what if we had only two systems to begin with, and one of the two fails in the same way? The determined correction needed goes from [0,0] to [0,+50]. Quick now: which value is correct? Should you maintain state, or correct by +50?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At that point, &lt;strong&gt;there is no way to know&lt;/strong&gt; whether correcting by 0 or +50 is the proper course of action. You could take an average, but using an average of two numbers (one of which is likely to be incorrect) could actually be &lt;em&gt;worse&lt;/em&gt; than either value by itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By adding a third system to the redundant set, you add a tie-breaker for the situation where there is one malfunctioning system. Only if two of the three systems start to malfunction at the same time do you have an actual problem, and if the aircraft is having such problems that two out of three redundant systems are giving erroneous outputs then you likely have some serious trouble to begin with.&lt;/p&gt;&#xA;" OwnerUserId="753" LastEditorUserId="753" LastEditDate="2017-10-07T17:27:45.523" LastActivityDate="2017-10-07T17:27:45.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13481" PostTypeId="1" AcceptedAnswerId="13482" CreationDate="2015-03-25T12:58:29.223" Score="12" ViewCount="2305" Body="&lt;p&gt;In a news article I saw this &lt;a href=&quot;https://www.jyllands-posten.dk/pictures/NICA_Billede__free_/article7581443.ece/ALTERNATES/h-free/OK-sort-boks-fra-Germanwings&amp;#39;-Airbus-A320-fly&quot; rel=&quot;nofollow noreferrer&quot;&gt;picture of a black box&lt;/a&gt; from a crashed A320. The article mentioned that finding the black box had lead to some disappointment due to the black box having been damaged:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.jyllands-posten.dk/pictures/NICA_Billede__free_/article7581443.ece/ALTERNATES/h-free/OK-sort-boks-fra-Germanwings&amp;#39;-Airbus-A320-fly&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3HdiDm.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This got me wondering where the actual data storage is located inside the black box. The cylindrical piece on the left looks like it is designed to be more robust than the rest of the hardware, so I am guessing that is where the data storage is located.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the reports of the damage exaggerated in this case? Or is any of the critical data stored in those parts of the device which have been damaged?&lt;/p&gt;&#xA;" OwnerUserId="7450" LastEditorUserId="7450" LastEditDate="2018-11-03T12:56:24.450" LastActivityDate="2018-11-03T12:56:24.450" Title="Where inside a black box is the data storage located?" Tags="&lt;cockpit-voice-recorder&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="13482" PostTypeId="2" ParentId="13481" CreationDate="2015-03-25T13:06:53.867" Score="22" Body="&lt;p&gt;The image of the recovered &quot;black box&quot; is showing the Cockpit Voice Recorder (CVR). The data is stored in the cylindrical housing that was relatively undamaged in the crash. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The housing consists of a stainless steel outer shell to withstand impact forces. Beneath it is a layers of high temperature insulation to protect the data storage from post crash fire.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hp64L.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="65" LastEditDate="2015-03-25T13:09:00.820" LastActivityDate="2015-03-25T13:09:00.820" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13483" PostTypeId="1" CreationDate="2015-03-25T13:08:36.417" Score="3" ViewCount="686" Body="&lt;p&gt;Where I can find the information about fuel type and fuel consumption for PW 1000G engines family?&lt;/p&gt;&#xA;" OwnerUserId="7777" LastEditorUserId="97" LastEditDate="2015-05-03T01:43:46.493" LastActivityDate="2015-06-10T21:53:00.490" Title="Where to find fuel type &amp; fuel consumption info for PW 1000G engines family?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13484" PostTypeId="2" ParentId="13458" CreationDate="2015-03-25T13:18:29.237" Score="2" Body="&lt;p&gt;I dont know of a site that has it for every airport but &lt;a href=&quot;http://www.liveatc.net/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; site has lots of live streaming ATC. It seems they have ATIS for some airports (I found it for JFK) but chances are they will only have it for the big airports however depending on where you fly out of you may get lucky. Again this is the actual audio feed so you will still need to listen to it. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-25T13:18:29.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13485" PostTypeId="2" ParentId="13460" CreationDate="2015-03-25T13:24:41.777" Score="15" Body="&lt;p&gt;Spending years being ferried off and on shore by helicopters, I'd say the biggest problem is noise. Even with a pair of decent ear defenders on it's not exactly quiet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, so a commercial 'air bus' is never going to match a Mercedes or even a plush executive helicopter for levels of NVH, but there's nothing particularly attractive about the experience other than getting somewhere much quicker than you might otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The noise also means the 'go anywhere' ability of helicopters is severely curtailed if noise means they can't actually go many places.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add to that the high cost and it's pretty much a non-starter except for edge cases as in SentryRaven's answer where an increase of speed of an order of magnitude or more, or the circumvention of otherwise impossible access outweigh these concerns.&lt;/p&gt;&#xA;" OwnerUserId="1563" LastEditorUserId="1563" LastEditDate="2015-03-26T15:41:26.850" LastActivityDate="2015-03-26T15:41:26.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13486" PostTypeId="2" ParentId="13460" CreationDate="2015-03-25T13:26:38.547" Score="6" Body="&lt;p&gt;There are a few commercial passenger flights, but not so many because of the costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Sao Paulo, Brazil, there are &lt;a href=&quot;http://lab.org.uk/sao-paulo-the-worlds-biggest-helicopter-fleet&quot;&gt;about 500 registered helicopters&lt;/a&gt;, with about 700 flights per day, which include transporting CEOs and politicians from one part of the city to another. Several factors contribute to this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Frequent traffic issues leading to unpredictable delays in major roads;&lt;/li&gt;&#xA;&lt;li&gt;Presence of an elite having enough money to afford such flights;&lt;/li&gt;&#xA;&lt;li&gt;Availability of a sufficient number of helipads.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some might also cite safety concerns, but this is unlikely to play a major role.&lt;/p&gt;&#xA;" OwnerUserId="7782" LastActivityDate="2015-03-25T13:26:38.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13487" PostTypeId="1" AcceptedAnswerId="13489" CreationDate="2015-03-25T15:19:18.840" Score="26" ViewCount="5051" Body="&lt;p&gt;There are 4 arresting wires on an aircraft carrier separated by about 50 feet and usually the pilot tries to snag the 3rd one but he does have the option to snag the first or second one.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What stops the tailhook from engaging the wires in front of the airfraft as well?   Is it assumed that they will also get engaged and the regulator on each arresting engine is tuned to accept it?&lt;/p&gt;&#xA;" OwnerUserId="7788" LastActivityDate="2019-04-29T04:03:12.687" Title="Can a landing aircraft snag multiple wires when landing on an aircraft carrier?" Tags="&lt;aircraft-carrier&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13488" PostTypeId="2" ParentId="13458" CreationDate="2015-03-25T15:43:15.433" Score="2" Body="&lt;p&gt;In the US ATIS information isn't available on the internet. &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/fac/0304.html&quot; rel=&quot;nofollow&quot;&gt;The tapes (or an equivalent written record) are retained like any other ATC communication though&lt;/a&gt; (3-4-2 item &quot;k&quot;) and are available via FOIA requests if you have a pressing need for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all you're interested in is the weather most airports that are large enough to warrant an ATIS broadcast are also large enough to have a weather station reporting METARs, which means you can use &lt;a href=&quot;http://www.ogimet.com/metars.phtml.en&quot; rel=&quot;nofollow&quot;&gt;one of the many available METAR archive search websites&lt;/a&gt; (or if you prefer you can dig around on the NOAA website - I used to know the URL for the archive but it's apparently been moved).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-25T15:43:15.433" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13489" PostTypeId="2" ParentId="13487" CreationDate="2015-03-25T15:55:05.903" Score="32" Body="&lt;p&gt;The answer is quite simple:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1.&lt;/strong&gt; When touching down the nose is in a pulled up attitude, therefore the tail is farther down then normal. As soon as the airplane touches down (on all wheels), the tail is higher, thus the hook is higher. &lt;img src=&quot;https://i.stack.imgur.com/n5B2W.jpg&quot; alt=&quot;You can see how the aircraft is in a nose up attitude, but gear and hook are on the same level.&quot;&gt;&#xA;You can see how the aircraft is in a nose up attitude, but gear and hook are on the same level. If the aircraft was sitting on all its tires, the hook would actually touch the ground. (This might not even be the case on all aircraft, though!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2.&lt;/strong&gt; This is the much more important reason: The hook is pneumatically pushed onto the deck (Google for the &quot;F-14 Tomcat Pilot's Flight Operating Manual Vol. 1, Volume 1&quot;. Interestingly Wikipedia (is it a source?) says there are hydraulic and pneumatic hooks) but as soon as the hook hooks to the cable, and pulls on it, that pneumatic pressure is overcome and the vectors of the forces go from where the hook is attached to the plane to where the wire comes out of the ground (and vice versa). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I guess its a combination of both, hydraulic and pneumatic. As hydraulics are not compressible, a valve would be needed to release the pressure built by the yank of the cable. So air pressure (pneumatics) would probably do a better job on keeping the hook down as long as no cable is attached. The retraction of the hook is done hydraulically though, and the way it is written in the F-14 Tomcat Pilot's Flight Operating Manual Vol. 1, Volume 1 it seems like the pneumatic pressure is kept even with the hook retracted... &lt;img src=&quot;https://i.stack.imgur.com/qWlm0.jpg&quot; alt=&quot;Side view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see here, the hook is actually almost parallel to the deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3.&lt;/strong&gt; Last but not least: There is no space for two wires on one hook. Let's say the airplane would catch the first rope, and for some reason (it should definitely not happen, but let's just pretend it does) the hook is still on the ground where it would hook up to the second wire when crossing it, then it will maybe drag it along for a short time, but it can't really hook on as the hook is made to fit exactly one wire. This can be seen on this picture:&lt;img src=&quot;https://i.stack.imgur.com/1nzOF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="5592" LastEditDate="2019-03-07T13:52:05.040" LastActivityDate="2019-03-07T13:52:05.040" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="13491" PostTypeId="2" ParentId="13459" CreationDate="2015-03-25T17:20:45.227" Score="3" Body="&lt;p&gt;&lt;em&gt;(not exactly an answer, I know... a bit more of a discussion)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Okay, ADS-B is vulnerable to spoofing.  What could be done about that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the FAA hasn't been exactly forthcoming with their plans, I've seen articles in the past that suggest they can match up the ADS-B report, the receiving station, and a radar return for some level of discrimination.   Doing a match-up, a ground-receiver in Montana would automatically ignore any location info that claims to be in Florida.  A plane in Montana could spoof its exact location by a few dozen miles, but couldn't lie enough to be in an entirely different ARTCC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because it is a digital format, one idea is to make transmitters have digital certificates, so they must sign each transmission with their certificate.  By default, all receivers would see all messages, and a spoofer could still insert false messages.   However, once a transmitter is identified as sending out bogus messages, it would be trivial to set a &quot;Ignore all messages from Tx 1357&quot; filter.  The problem is coming to the initial recognition that a transmitter is lying in the first place.  And once its false messages are ignored, the big question is &lt;em&gt;&quot;So... this plane isn't where it claims to be.  Where is it actually??&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short: there are mitigation steps, but nothing that can automatically and completely secure a system when anyone can be a transmitter.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-03-25T17:20:45.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13492" PostTypeId="2" ParentId="13459" CreationDate="2015-03-25T18:09:28.093" Score="15" Body="&lt;p&gt;Yes, one can send deliberately wrong position reports. But why would anyone want to do that? We're assuming malicious intent, of course -- but even so?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could an attacker &lt;strong&gt;cause a collision&lt;/strong&gt; using fake position broadcasts? It is hard to see how. The core meaning of an ADS-B broadcast is basically, &lt;em&gt;&quot;Dear ATC, please don't clear anyone to fly too near such-and-such point in space, because that's where I am.&quot;&lt;/em&gt; Getting an unsuspecting other aircraft to avoid a particular point in space where in reality nobody is, will not in itself cause any accident. At most some distraction and swearing and &quot;no sir, I reallly don't see that traffic&quot; transmissions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An attacker might mount a &lt;strong&gt;denial of service&lt;/strong&gt; attack against the airspace by flooding an air traffic controller's monitor with dummy aircraft, so he can't find any safe way to route the real planes he's talking to. But for that effect it's not really necessary to send any fake position reports -- simply jamming the 1090 MHz downlink frequency would do just as well, and not be significantly more illegal or harder to detect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could try to convince ATC that &lt;strong&gt;someone else&lt;/strong&gt; is in a different place than they really are. However, unless you jam the entire frequency, ATC would still be able to hear their &lt;em&gt;real&lt;/em&gt; position reports, and their computers would be able to tell that they have several inconsistent reports from the same airframe address. It would be simple to handle that by separating traffic from both reported positions (which they need to be able to anyway, just in case someone accidentally misconfigures their transponder with a wrong address), and then we're back in the DoS scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could a suicidal attacker go up in an airplane of his own and get to &lt;strong&gt;ram into somebody else&lt;/strong&gt; while faking his position as far as ATC sees it? If that's your goal, it would certainly seem helpful to &lt;em&gt;stop broadcasting yoru true position&lt;/em&gt;, but that doesn't mean that broadcasting a &lt;em&gt;false&lt;/em&gt; position would buy you anything that you don't also get simply by pulling the plug on your transponder so you don't broadcast &lt;em&gt;anything&lt;/em&gt;. In both cases your problem would be that you're now a primary radar echo that doesn't correspond to any transponder reply. Depending on where you pull the trick that may or may not set alarm bells ringing -- but to the extent it does, broadcasting a &lt;em&gt;different&lt;/em&gt; position wouldn't do anything to silence them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing you &lt;em&gt;can&lt;/em&gt; do is rig your ADS-B Out to transmit a &lt;strong&gt;wrong altitude&lt;/strong&gt; and hope to get clearance to pass directly above or below someone which you might then try to ram without being seen -- because primary radar is generally bad at distinguishing altitudes. However, that is not a risk specific to ADS-B -- good old SSR &lt;em&gt;also&lt;/em&gt; depends on airborne transponders to self-report their altitude in Mode C, and that can be tampered with just as easily.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-03-25T18:09:28.093" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13493" PostTypeId="2" ParentId="12656" CreationDate="2015-03-25T18:32:50.507" Score="-1" Body="&lt;p&gt;In addition to the power-to-weight ratio - already aptly described above - I bluntly strike at the economic reasons and cite that bean-counters look at the cost-per-takeoff and shake their head. &lt;/p&gt;&#xA;" OwnerUserId="7708" LastActivityDate="2015-03-25T18:32:50.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13494" PostTypeId="2" ParentId="13487" CreationDate="2015-03-25T20:04:20.440" Score="16" Body="&lt;p&gt;No, the hook is not capable of catching more than a single wire at a time.  There is a hydraulic dampener in the hook, the snubber, that keeps the hook pressed into the deck during touchdown.  This was designed to help alleviate a phenomenon known as &lt;em&gt;hook skip bolters&lt;/em&gt;, when the force of the hook contacting the deck causes the hook to bounce; however, the hydraulic force of the snubber pressure is immediately overcome when the hook catches a wire, and the hook is drawn up almost parallel to the flight deck as the cable arrests the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="11215" LastEditDate="2017-10-11T02:36:12.150" LastActivityDate="2017-10-11T02:36:12.150" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13495" PostTypeId="1" CreationDate="2015-03-25T20:04:39.990" Score="0" ViewCount="376" Body="&lt;p&gt;Assuming the plane is on autopilot: for example, if a plane is flying high (over 20000 feet) and its autopilot receives a positive value of external temperature, which is clearly abnormal or impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What will the autopilot do with such a obviously wrong information?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="7799" LastEditorUserId="5592" LastEditDate="2015-03-25T22:01:18.223" LastActivityDate="2020-12-14T09:46:27.753" Title="How does the autopilot act when it receives an obviously bad temperature value?" Tags="&lt;autopilot&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13498" PostTypeId="1" AcceptedAnswerId="13499" CreationDate="2015-03-25T20:49:46.473" Score="11" ViewCount="1884" Body="&lt;p&gt;I think that the glass cockpit of a modern plane has some sort of a central power supply or at least some central controlling software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens if this central power suddenly disappears, or the central software freezes? Yes, of course, this would be a severe failure and would put everybody's life on the plane in serious danger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is such a failure possible?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="7794" LastEditorUserId="5517" LastEditDate="2016-04-08T12:52:19.813" LastActivityDate="2020-12-02T02:22:45.897" Title="Can a software &quot;hard freeze&quot; or serious hardware problem completely disable the whole cockpit?" Tags="&lt;flight-controls&gt;&lt;avionics&gt;&lt;glass-cockpit&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13499" PostTypeId="2" ParentId="13498" CreationDate="2015-03-25T20:58:18.677" Score="13" Body="&lt;p&gt;If the power suddenly disappears to any aircraft (ie, a total electrical failure including the batteries), then all the aircraft systems will be failed regardless of whether or not they were glass.  This is highly unlikely because there are several power generation backups that would have to fail, including the batteries themselves, before this ever became a reality.  Unfortunately though, if the aircraft &lt;em&gt;only&lt;/em&gt; has electrically controlled, hydraulically actuated control surfaces (fly-by-wire), vice actual mechanical linkages (or backup controls), then a total electrical failure would be 100% fatal if power cannot be restored.  The control surfaces would not be movable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, more to the question regarding software bugs, all primary flight instruments are backed up to prevent such disasters from happening.  I have personally lost all the digital displays in my cockpit and flown a no-gyro, surveillance approach in bad weather using nothing but a peanut gyro.  Its possible, but definitely not a good time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything is possible.  However, even though the odds of a total electrical failure, or complete loss of instrumentation (including backups) is nominally greater than 0%, the statistical probably can still probably be rounded to 0.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-03-26T02:56:59.810" LastActivityDate="2015-03-26T02:56:59.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13501" PostTypeId="2" ParentId="13453" CreationDate="2015-03-25T21:04:14.143" Score="6" Body="&lt;p&gt;If you know the pressure coefficient of the flow, the rest is easy. The equation for the pressure coefficient $c_p$ is:&#xA;$$c_p = \frac{p - p_{\infty}}{q_{\infty}} = 1 - \left(\frac{v}{v_{\infty}}\right)^2$$&#xA;$q_{\infty}$ is the dynamic pressure and contains air density $\rho$ and the flight speed $v_{\infty}$:&#xA;$$q_{\infty} = \frac{\rho}{2}\cdot v_{\infty}^2$$&#xA;The equation for the local speed, relative to flight speed, is:$$\frac{v}{v_{\infty}} = \sqrt{1 - \frac{p - p_{\infty}}{q_{\infty}}} = \sqrt{1 - c_p}$$&#xA;Now you need to know the pressure coefficient. At Mach 0.85 the local Mach number of the 747 wing, which has a wing sweep of 37.5°, is 0.674. Since I do not have the airfoil of the 747-400, I used one from the same family (BACJ), found &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/B747PresS07.pdf?q=747&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. If you are interested, many more can be found in Michael Selig's &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/coord_database.html&quot; rel=&quot;noreferrer&quot;&gt;immense airfoil database&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xev7k.png&quot; alt=&quot;B747 Mach distribution&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot is from a &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/tsfoil2.f&quot; rel=&quot;noreferrer&quot;&gt;TSFOIL&lt;/a&gt; calculation of the 2D flow around BACJ at Mach 0.8, so it needs to be taken with a grain of salt. Note that it shows a stagnation point, and, therefore, Mach = 0 at the leading edge. The leading edge of the 747 wing is swept by 45°, so it will only slow the orthogonal speed component to zero. Consequently, the 747 wing has a stagnation line where the lowest speed will still be Mach 0.6. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the suction side, the airfoil reaches Mach = 1.2 quickly and even Mach 1.3 near the trailing edge. Modern, so called &lt;a href=&quot;http://en.wikipedia.org/wiki/Supercritical_airfoil&quot; rel=&quot;noreferrer&quot;&gt;supercritical airfoil&lt;/a&gt;s can tolerate mildly supersonic speeds on their suction side, and the Boeing 747-400 makes use of them. However, since the wing sweep reduces Mach effects, the top speed will be Mach 1.2 or slightly lower, and the TSFOIL calculation shown here is not exactly correct for flight at Mach 0.85, but gives a general idea what happens on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the many questions you posted directly:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The shape of the airfoil is immensely important. Thicker airfoils need to displace more air, and higher flow speeds are created on both sides. Camber will increase the pressure (and speed) difference between both sides.&lt;/li&gt;&#xA;&lt;li&gt;Changing the angle of attack will add a roughly triangular difference, which is highest at the leading edge, to the difference between both sides. Lower side pressure is increased slightly, and upper side suction goes up by a lot at the nose.&lt;/li&gt;&#xA;&lt;li&gt;Good wing designs have a triangular lift distribution over wing span, with the highest lift at the root. Since the displacement effect of the fuselage is added to the flow effects, the highest speeds will be encountered at the wing root.&lt;/li&gt;&#xA;&lt;li&gt;Just look at the pretty pictures ...&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-07T06:03:13.140" LastActivityDate="2015-05-07T06:03:13.140" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13502" PostTypeId="2" ParentId="13495" CreationDate="2015-03-25T21:46:18.530" Score="0" Body="&lt;p&gt;I can not tell you what happens if there is a positive value for the temperature above 20000ft, but here is some general information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this issue I will be talking about Airbus planes, as they are known to be very &quot;smart&quot; planes. &lt;strong&gt;There are hundreds of algorithms that try to prevent wrong data input from being an issue.&lt;/strong&gt; But those do not always work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take Qantas Flight 72 for example: &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_72&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Wikipedia&lt;/a&gt; the airplane all of the sudden pitched down violently, as if it was trying to prevent a stall from happening. This was because the average of the two angle of attack sensors was way out the box. Though there was a (very smart) algorithm rechecking the values, it could not deal with multiple wrong values with a certain amount of time - and made the airplane pitch down.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This being an example where the plane actually acted by itself due to a faulty value, here is the general case: If the airplane notices odd values, which it will usually recognize (e.g. a positive temperature), it blanks out the display so that a pilot can not be mislead. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying smaller airplanes, you often practice &quot;partial panel flying&quot;, where your flight instructor covers up some instruments and you have to fly the aircraft with alternative instruments. As you can see this is well practiced and &#xA;shouldn't be a problem. Unfortunately though, this makes flying a lot harder which can cause crashes to happen (&lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;AF447&lt;/a&gt;,&lt;a href=&quot;http://en.wikipedia.org/wiki/Indonesia_AirAsia_Flight_8501&quot; rel=&quot;nofollow noreferrer&quot;&gt;QZ8501&lt;/a&gt;, and more).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, whenever the autopilot finds itself in a situation that it can't handle, for example when the pitot static system fails, it will disconnect and refuse to connect, giving the pilot full control (or rather as full control as possible on an Airbus) of the aircraft. This disengagement ensures the plane not to do something stupid due to wrong inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion: For redundancy most systems exist two or three times working parallel to provide backup, same goes for sensors. If all data inputs report something obviously wrong, the pilot will not see this wrong information so he can concentrate on what he has.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/13447/5592&quot;&gt;this question&lt;/a&gt; can also give you a little more information about computer redundancy on aircraft&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-26T10:48:35.393" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13503" PostTypeId="2" ParentId="5041" CreationDate="2015-03-25T22:17:47.630" Score="1" Body="&lt;p&gt;You can access the &lt;a href=&quot;https://aerospace.honeywell.com/en/products/information-and-maintenance-management/flight-recorders&quot; rel=&quot;nofollow&quot;&gt;Honeywell website&lt;/a&gt; and download and read the manuals, brochures, drawings and schematics about connections of voice and data recorders. Honeywell is the largest manufacturer of black boxes for commercial, civil and military aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Honeywell was among those who provided the black boxes for the A320 that crashed in the French Alps. There are many models and types of Flight Data Recorders (FDR) and Cockpit Voice Recorders (CVR), and they also record the status of other devices. There are many types of FDR's and CVR's whose characteristics depend on the type of aircraft and customer specifications.&lt;/p&gt;&#xA;" OwnerUserId="7805" LastEditorUserId="1696" LastEditDate="2015-03-26T01:55:13.530" LastActivityDate="2015-03-26T01:55:13.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13504" PostTypeId="2" ParentId="13447" CreationDate="2015-03-25T22:24:10.763" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If a microprocessor is overheated or overloaded and spontaneously&#xA;  fails, I would expect it to stop doing anything and produce no output.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Have you ever overclocked a CPU, or watched an old piece of hardware die?  You can get all kinds of weird artifacts while the cpu is still running.&lt;/p&gt;&#xA;" OwnerUserId="1622" LastEditorUserId="1622" LastEditDate="2015-03-25T22:31:14.057" LastActivityDate="2015-03-25T22:31:14.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13505" PostTypeId="2" ParentId="13498" CreationDate="2015-03-26T00:11:07.930" Score="8" Body="&lt;p&gt;While total electrical failure in a transport-category aircraft is extremely remote, even most fly-by-wire airliners such as the A320/330/340 and B777/787 have redundant backups that would work under the scenario: in the case of the Airbus, you'd fly using the rudder pedals for yaw and roll and manual stabilizer trim for pitch, while Boeing uses a pair of spoiler panels for mechanical roll backup instead of the rudder.&lt;/p&gt;&#xA;&lt;p&gt;All of this, of course, depends on the presence of actuator hydraulic power - if you have no hydraulic power and no electric power on a FBW Airbus or Boeing (including a loss of the dedicated FADEC/EEC backup permanent magnet generators), you're toast because not even &amp;quot;fly by thrust lever&amp;quot; a la UAL232 and OO-DLL will save you in that case.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2020-12-02T02:22:45.897" LastActivityDate="2020-12-02T02:22:45.897" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="13506" PostTypeId="2" ParentId="13498" CreationDate="2015-03-26T00:52:31.787" Score="3" Body="&lt;p&gt;There have been incidents where the primary flight displays have failed somewhat as you describe: &lt;a href=&quot;http://avherald.com/h?article=47a027e1&quot; rel=&quot;nofollow&quot;&gt;example 1&lt;/a&gt;, &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-433616.html&quot; rel=&quot;nofollow&quot;&gt;example 2&lt;/a&gt; (one each for Boeing and Airbus so I'm not taking sides). So yes, things can fail, causing cockpit displays to go blank and other problems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there's a lot of redundancy in these systems. Cockpit display systems are somewhat separate from flight control systems, so the failure of one may not impact the other. As &#xA;UnrecognizedFallingObject notes, there are even some options for manual control in the event of a total fly-by-wire failure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern glass cockpit aircraft have a small display, usually toward the center, with standby instruments (Airbus calls it the Integrated Standby Instrument System). This is a separate LCD display, powered independently by the emergency bus and driven by its own computer, designed to display altitude, airspeed, and attitude. This provides the crew with essential information toward making an emergency landing. &lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2015-03-26T00:52:31.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13507" PostTypeId="2" ParentId="13498" CreationDate="2015-03-26T00:54:59.500" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;But, is such a failure possible?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer to if such a failure is possible is on some level yes. But for what its worth no. There are a few things to consider. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Redundant and Independent systems:&lt;/strong&gt; Aircraft typically have not only redundant systems but independent systems in other words not only are there back ups but they are often separated so that a failure in a single system or set of systems should remain isolated. From a power standpoint a plane gets is electrical power from the turbines driving a generator. Each turbine has at least one generator (maybe more Im not sure) so if a single engine were to cut out you would not lose power generation. You may need to shut the lights off to not over draw the generator but you could still power the key systems. Aircraft also have batteries in the case of total engine failure. keep in mind that in a total engine failure you will be on the ground long before you kill the batteries I would think.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Multiple Electronic Busses:&lt;/strong&gt; To my knowledge larger airplanes have multiple electric busses each of with can be independently tied to and disconnected from the main buss as well as joined if needed. If one buss fails you can switch over to the other to draw power for the aircraft. Keep in mind that if a surge causes the failure the components would be protected by the fuses. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is even finding its way into smaller GA airplanes. It is possible to order some small planes with 2 alternators now I believe the Cirrus SR-22 can be had in such a configuration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that we have established that there are actually multiple central power connections lets look at why its so remote they fail. If you take 2 systems that are (for the purpose of this example) created equally, have the same run times on them and are serviced the same etc. they would have the same chance of failing at any given moment in time. That being said the chances of them both failing at the same point in time is so remote it can almost be ignored. The idea here is that we can accept a single system failure, complete the flight, and then send the plane in for repair.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-26T00:54:59.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13509" PostTypeId="1" CreationDate="2015-03-26T01:59:42.837" Score="11" ViewCount="421" Body="&lt;p&gt;I need to know when the mandate to maintain a logbook started. Was it a US requirement, or was it from another regulator in the world? Did the aircraft logbook start at the same time as the pilot logbook? &lt;/p&gt;&#xA;" OwnerUserId="7812" LastEditorUserId="97" LastEditDate="2015-03-26T02:40:17.177" LastActivityDate="2015-03-26T14:04:00.290" Title="What is the history of the aircraft logbook?" Tags="&lt;faa-regulations&gt;&lt;aviation-history&gt;&lt;regulations&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13510" PostTypeId="1" CreationDate="2015-03-26T03:29:42.740" Score="1" ViewCount="179" Body="&lt;p&gt;Are there any companies that use atom interferometers in aircraft? If so, are they used for navigation? If not, is it possible to assemble it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the link from wiki &lt;a href=&quot;https://en.wikipedia.org/wiki/Atom_interferometer&quot; rel=&quot;nofollow&quot;&gt;Atom interferometer&lt;/a&gt; and link from &lt;a href=&quot;http://www.technologyreview.com/view/425584/first-use-of-atom-interferometer-to-measure-aircraft-acceleration/&quot; rel=&quot;nofollow&quot;&gt;MIT Technology Review of it&lt;/a&gt; and a link from a company work on it.&lt;/p&gt;&#xA;" OwnerUserId="7814" LastEditorUserId="5517" LastEditDate="2015-03-26T12:13:57.967" LastActivityDate="2015-03-26T18:42:13.243" Title="Are there any companies that use atom interferometers in aircraft?" Tags="&lt;measurement&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13511" PostTypeId="2" ParentId="13510" CreationDate="2015-03-26T03:40:44.813" Score="8" Body="&lt;p&gt;&lt;strong&gt;Probably not.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 2012 paper &lt;a href=&quot;http://www.mdpi.com/1424-8220/12/5/6331&quot; rel=&quot;noreferrer&quot;&gt;Advances in Atomic Gyroscopes: A View from Inertial Navigation Applications&lt;/a&gt;* states in the abstract that &quot;there are still lots of problems that need to be overcome to meet the requirements of inertial navigation systems.&quot; Even once atomic inferometer gyroscopes are able to meet the basic requirements of inertial navigation systems, it will take years of testing and certification before they will actually be used in production aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I highly suggest reading that paper if atomic physics is your thing, but for us the conclusion is gold:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Recent progress on atomic gyroscopes has demonstrated that AIG is an&#xA;  ultra-high precision gyroscope for strategic grade inertial navigation&#xA;  in the future, and ASG is a high performance gyroscope which features&#xA;  both high precision and compact size. There are still lots of problems&#xA;  that need to be overcome when considering the atomic gyroscope for&#xA;  inertial navigation applications, however with the technologies&#xA;  available in the near future, the AIG could be used in space for&#xA;  fundamental physics research, the ASG based on comagnetometer can be&#xA;  used in strategic grade gimbaled INS, and the navigation grade ASG&#xA;  based on NMR can be demonstrated on chip-scale size. Furthermore, with&#xA;  the development of new theories and technologies for atomic&#xA;  manipulation, the future of high performance inertial navigation&#xA;  applications using AIG and ASG is indeed bright.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would be slightly more cynical about time scales than this paper. &lt;a href=&quot;http://www.imar-navigation.de/downloads/papers/inertial_navigation_introduction.pdf&quot; rel=&quot;noreferrer&quot;&gt;This intro to INS&lt;/a&gt; notes on page 5 that it took &lt;em&gt;18 years&lt;/em&gt; for ring laser systems to reach maturity. No current atomic gyroscope system can meet the performance of ring laser systems, and the highest-performance AIG systems are on the order of a cubic meter. Chip-scale ASG systems have been produced, but their performance is dreadful compared to mechanical or ring laser systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Note: I'm not sure how much to trust this article. It's published in a peer-reviewed journal, but there are clear copyediting errors. I don't have a better source, though, so I'll trust it for the purposes of this question. Also, note that this paper does not only have aviation users in mind; there are a lot of references to strategic INS, which I think refers to submarines, and it also talks about INS in the context of satellites.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-03-26T18:42:13.243" LastActivityDate="2015-03-26T18:42:13.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13512" PostTypeId="1" CreationDate="2015-03-26T00:53:15.047" Score="1" ViewCount="755" Body="&lt;p&gt;I am just reading the latest news on the air plane crash that happened couple days ago and it dawned on me that one too many times have I read a story on the &lt;a href=&quot;http://www.nytimes.com/2015/03/26/world/europe/germanwings-airbus-crash.html?smid=tw-bna&quot; rel=&quot;nofollow&quot;&gt;NY Times&lt;/a&gt; where after black box is obtained, it provided no additional information and almost always resulted in mystery. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;MH370 of course demonstrated the failure of a tool such as the black box which has limited battery and no accessibility. Many commented at that time even my own phone can be quickly located once lost, how do they lose a component in a couple million dollar passenger plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air Indonesia crash further demonstrated how due to noise, the recorded data cannot be made out exactly what happened. Yes, that is precisely the problem with a voice recorder - noise is captured as well as speech and if SNR is high enough, you don't hear the speech. You would have thought engineers in this century knew better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many have advocated a live video streaming device such as those for CCTV. Other have suggested float on water or a better accessed versions of modern black boxes. What is the technological infeasibility here that is preventing electrical engineers from taking a more active stance towards creating a better black box? What are some of the ways that a better black box can be made?&lt;/p&gt;&#xA;" OwnerDisplayName="Project Backlog" LastEditorUserId="97" LastEditDate="2015-05-03T02:03:11.547" LastActivityDate="2015-05-03T02:03:11.547" Title="Are plane's black boxes essentially useless tool in the modern age and how to improve upon it?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-03-26T07:22:07.883" ContentLicense="CC BY-SA 3.0" />
  <row Id="13513" PostTypeId="1" AcceptedAnswerId="13934" CreationDate="2015-03-26T05:10:18.140" Score="20" ViewCount="4972" Body="&lt;p&gt;What are the typical non-aircraft duties for an airline pilot? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By non-aircraft, I'm asking about time spent in the office, in meetings, training (whether in a simulator, class or other non-aircraft environment), deadheading or being at the airport but not actually in the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand there is paperwork and pre-flight planning done on the ground between flights while in the cockpit, so I'm not asking about this. I'm really trying to get an idea about what other work related activities you do which does not involve you being in the cockpit (except perhaps purely as a work-related passenger).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way of asking this question would be, &quot;what work besides flying planes does an airline pilot normally do, or might reasonably be expected to do, as part of his or her job?&quot;&lt;/p&gt;&#xA;" OwnerUserId="2693" LastEditorUserId="2693" LastEditDate="2015-03-27T03:30:50.333" LastActivityDate="2015-10-23T09:46:43.617" Title="What work besides flying planes does an airline pilot regularly do?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13514" PostTypeId="2" ParentId="13512" CreationDate="2015-03-26T05:15:12.727" Score="6" Body="&lt;p&gt;We have this topic well covered &lt;a href=&quot;https://aviation.stackexchange.com/questions/7739/can-airplanes-transmit-relay-flight-data-to-atcs-periodically-while-in-flight&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/7839/are-there-any-proposals-to-continuously-stream-black-box-data&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1147/could-the-cvr-and-fdr-record-to-the-cloud&quot;&gt;here&lt;/a&gt; (which is the granddaddy of them all).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, it comes down to two issues:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Regulation: It takes a long time for innovations to be approved, especially in safety-related applications.&lt;/li&gt;&#xA;&lt;li&gt;On long-range flights there are long stretches of no radio contact (except maybe for a satellite connection), so streaming becomes impractical due to the data volume.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Black boxes have been improved a lot since their introduction and they &lt;a href=&quot;https://aviation.stackexchange.com/questions/8310/why-are-fdrs-and-cvrs-still-two-separate-physical-devices&quot;&gt;continue to get better&lt;/a&gt;. Please let the investigators find and analyze the recordings first before jumping to conclusions.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-26T07:10:44.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13516" PostTypeId="2" ParentId="13512" CreationDate="2015-03-26T06:45:10.943" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are plane's black boxes essentially useless tool in the modern age&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, they are very, very &lt;strong&gt;useful&lt;/strong&gt; tool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In MH370, somebody clearly took some care in stopping any position reports from the plane, so if it had any kind of data streaming, it would most likely have been cut as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In QZ8501, if the recording was streamed, it would still contain the same data, so streaming it wouldn't help. Besides the “noise” is the warnings the system produced which are important part of the information the investigators need. What I am not sure is whether the content of the ECAM screen is recorded in the FDR; which warnings were generated is probably the most important bit of information in that accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In many other accidents, the flight data recorder and cockpit voice recorder provided exactly the information that was needed to investigate the accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, they could be improved. There are sure some engineers working on it. It however takes time to get any improvement in production, because every new black box design must first be thoroughly tested whether it's sufficiently resilient and reliable.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-03-26T06:45:10.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13518" PostTypeId="2" ParentId="13460" CreationDate="2015-03-26T08:29:12.070" Score="4" Body="&lt;p&gt;There was regular helicopter service between Tallinn, Estonia and Helsinki, Finland during the mid-2000's. It was mainly used by business travellers between the two cities. I think the flight time was something like 20 minutes and the heliport was on both sides conveniently in the middle of the city. The regular plane service has a flight time of 30 minutes with additional time spent for airport procedures and taxi rides to and from the airport, so there definetely was a business case there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However there was an unfortunate crash and the company never quite recovered from that. They use their copters for oil rig flights now, if I am not mistaken. See Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Copterline_Flight_103&quot; rel=&quot;nofollow&quot; title=&quot;Copterline flight 103&quot;&gt;Copterline Flight 103&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="5581" LastActivityDate="2015-03-26T08:29:12.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13519" PostTypeId="1" CreationDate="2015-03-26T08:39:34.793" Score="0" ViewCount="387" Body="&lt;p&gt;&lt;a href=&quot;http://www.iprr.org/manuals/Annex13.html&quot; rel=&quot;nofollow&quot;&gt;ICAO Annex 13&lt;/a&gt; defines an &quot;incident&quot; as&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is there good record keeping about incidents globally? Not like &lt;a href=&quot;http://aviation.globalincidentmap.com/&quot; rel=&quot;nofollow&quot;&gt;Aviation Global Incident Map&lt;/a&gt; which only really only lists accidents and some airport issues.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For completeness, the same document defines an &quot;accident&quot; to be&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight until such time as all such persons have disembarked, in which (a) a person is fatally or seriously injured [...], (b) the aircraft sustains damage or structural failure [...] or (c) the aircraft is missing or is completely inaccessible.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Only incidents that an airliner pilot is aware mid-flight and can do something about -this a start to follow-up.  question. Exact likelihood is not important- is it 10% or 20%. For passengers, the likelihood is not important since pilots handle mainly well. &lt;/p&gt;&#xA;" OwnerUserId="2671" LastEditorUserId="2671" LastEditDate="2015-03-28T14:50:04.673" LastActivityDate="2015-03-28T14:50:04.673" Title="What are the chances that you are on plane that has an incident?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="14" ClosedDate="2015-03-27T07:53:52.763" ContentLicense="CC BY-SA 3.0" />
  <row Id="13521" PostTypeId="1" AcceptedAnswerId="13524" CreationDate="2015-03-26T09:53:07.140" Score="2" ViewCount="1557" Body="&lt;p&gt;Is there a contingency for such a situation, where one of the pilots leaves the cockpit, the other pilot is incapacitated (for example losing consciousness) while the first pilot is still outside the cockpit and can not reenter the cockpit. If there is not, is that not a huge flaw, as multiple pilots are meant as a redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: This is in my opinion not a duplicate of &lt;a href=&quot;https://aviation.stackexchange.com/questions/11677&quot;&gt;this question&lt;/a&gt;, since the big problem in my question is the door to the cockpit being only openable from the outside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the linked question, the answer is simply &quot;both pilots being incapacitated at the same time is highly unlikely&quot;. The scenario I described is not highly unlikely. One of two pilots being incapacitated is not improbable and the door to the cockpit is only openable from the inside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if &lt;strong&gt;one pilot is incapacitated&lt;/strong&gt; while being temporarily alone in the cockpit, the other pilot is &quot;automatically&quot; locked out of the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="7823" LastEditorUserId="22550" LastEditDate="2018-12-14T18:00:23.050" LastActivityDate="2018-12-14T18:00:23.050" Title="What happens when a pilot is incapacitated?" Tags="&lt;emergency&gt;&lt;pilots&gt;&lt;cockpit&gt;&lt;pilot-incapacitation&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="1" ClosedDate="2015-03-26T10:31:24.190" ContentLicense="CC BY-SA 3.0" />
  <row Id="13522" PostTypeId="1" CreationDate="2015-03-26T09:54:57.153" Score="11" ViewCount="7504" Body="&lt;p&gt;Can a supersonic fighter incorporate a convergent nozzle or does it always have to be a convergent-divergent nozzle?&lt;/p&gt;&#xA;" OwnerUserId="7824" LastEditorUserId="19" LastEditDate="2015-03-26T11:41:37.050" LastActivityDate="2020-03-04T04:30:10.757" Title="Can a convergent nozzle be used for a supersonic jet engine?" Tags="&lt;jet-engine&gt;&lt;military&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13523" PostTypeId="2" ParentId="13521" CreationDate="2015-03-26T10:01:09.440" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a contingency for such a situation, where one of the pilots leaves the cockpit, the other pilot is incapacitated (for example losing consciousness) while the first pilot is still outside the cockpit and can not reenter the cockpit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, a keypad on the door will allow the second pilot back into the cockpit. It doesn't help when the pilot outside doesn't know/forgets the code or if the unlock code is denied from inside the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="572" LastEditDate="2015-03-26T10:02:49.113" LastActivityDate="2015-03-26T10:02:49.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13524" PostTypeId="2" ParentId="13521" CreationDate="2015-03-26T10:28:34.340" Score="3" Body="&lt;p&gt;There are contingency measures for PF incapacitation when PNF is absent from the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;This includes measures for cockpit decompression (e.g. window breaking)&lt;/p&gt;&#xA;&lt;p&gt;These measures are balanced with measures to prevent unauthorised passengers forcing entry to the cockpit, including by using force on cabin crew (or PNF) to make them open the cockpit door. Some of these measures are at the airline's discretion.&lt;/p&gt;&#xA;&lt;h2&gt;Cockpit door locks&lt;/h2&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.theguardian.com/world/2015/mar/26/germanwings-crash-safety-of-cockpit-doors-on-all-planes-questioned&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Guardian Newspaper&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A locked door is opened by a flight crew inside the cockpit but can also be unlocked by cabin crew entering a keycode from the outside. &lt;strong&gt;Crew inside the cockpit can manually override it to keep a door locked for up to five minutes&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;“In the case of an electrical supply failure the door is automatically unlocked, but remains closed,” reads the manual.&lt;/p&gt;&#xA;&lt;p&gt;It is equipped with a manual escape hatch but that is only accessible from the inside.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.latimes.com/world/la-fg-german-jet-crash-door-20150325-story.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The LA Times newspaper&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;safety protocols mandated by Congress in the U.S. after the Sept. 11 attacks ... eliminate the use of keys for entering the cockpit - assuring that no errant passenger can wrestle a key away from a crew member. ...&lt;/p&gt;&#xA;&lt;p&gt;If a member of the flight crew doesn't open the locked cockpit door from the inside, according to a manual for the Airbus A320 &lt;a href=&quot;http://nicmosis.as.arizona.edu:8000/ECLIPSE_WEB/TSE2015/A320_DOCUMENTS/A320_Operating_Manual_PDF_N_FCOM_RJA_TF_N_EU__20130329_DSC_25.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;available online&lt;/a&gt;, the door can also be unlocked by the cabin crew outside the cockpit by entering a two- to seven-digit code, pre-programmed by the airline, on a keypad.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;Cockpit occupancy&lt;/h2&gt;&#xA;&lt;p&gt;Guardian:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Protocols and standard procedures around what happens when a pilot leaves the cockpit mid-flight vary according to country and airline.&lt;/p&gt;&#xA;&lt;p&gt;A flight attendant taking the seat of an absent pilot to ensure there are always two people in the cockpit, and/or blocking access to the open door with a trolley, are often seen on US flights, but not necessarily on others, [Aviation expert Neil Handsford] said. For instance it is not a requirement on Australian flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;LA Times:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;American experts say the typical procedure is for a flight attendant to use a food cart to block access to the cockpit when the pilot opens the door to leave. A flight attendant is supposed to remain in the cockpit and open the door for the pilot upon his or her return. ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Airbus Manual&lt;/h2&gt;&#xA;&lt;p&gt;The Airbus manual referred to above says&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The Cockpit Door Locking System (CDLS) provides a means of electrically&#xA;locking and unlocking the cockpit door. This system is mainly&#xA;composed of :&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A keypad, located in the forward cabin, near the cockpit door,&lt;/li&gt;&#xA;&lt;li&gt;A toggle switch, located in the center pedestal’s Cockpit Door panel,&lt;/li&gt;&#xA;&lt;li&gt;A control unit and its CKPT DOOR CONT normal panel, located on&#xA;the overhead panel,&lt;/li&gt;&#xA;&lt;li&gt;A buzzer.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The keypad enables&#xA;the cabin crew to request access to the cockpit. There are two&#xA;different access request types : “Routine” and “Emergency” access&#xA;request (Refer to PRO-SUP-25 Cockpit Door Operation - General).&lt;/p&gt;&#xA;&lt;p&gt;The&#xA;toggle switch enables the flight crew to lock or unlock the cockpit&#xA;door, following an access request, thereby allowing or denying the&#xA;entry to the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;The cockpit door control unit is the system controller, in charge of :&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Locking or unlocking the door latches, upon flight crew action.&lt;/li&gt;&#xA;&lt;li&gt;Unlocking the door, in case of cockpit decompression&#xA;(the door then opens towards the cockpit under differential pressure).&lt;/li&gt;&#xA;&lt;li&gt;Indicating system failures of electrical latches and pressure sensors.&lt;/li&gt;&#xA;&lt;li&gt;Activating the access request buzzer and turning on the keypad LEDs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The buzzer sounds in the cockpit for 1 to 9 s to indicate that&#xA;a routine access request has been made, or sounds continuously if an&#xA;emergency access procedure has been initiated.&lt;/p&gt;&#xA;&lt;p&gt;The keypad is used to sound the buzzer in the cockpit for 1 to 9 s (3 s by default), by entering a zero to seven-digit code, as programmed by the airline, followed by the '#' key. It is also used to enter the two to seven-digit emergency code, followed by the '#' key, when the flight crew does not respond.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;There is also an &lt;a href=&quot;http://www.theguardian.com/world/video/2015/mar/26/airbus-safety-video-shows-cockpit-door-entry-procedure-germanwings-crash?CMP=twt_gu&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus Video&lt;/a&gt; that shows how the cockpit door lock operates normally and in the case of pilot incapacitation&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Abbreviations&lt;/p&gt;&#xA;&lt;p&gt;PF = Pilot flying, PNF = Pilot not flying.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-26T11:50:27.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13525" PostTypeId="2" ParentId="13495" CreationDate="2015-03-26T11:14:18.540" Score="5" Body="&lt;p&gt;The autopilot does not receive information about the outside temperature, it has no (direct) relation to what the autopilot controls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The autopilot receives aircraft state inputs like airspeed, Mach number, vertical speed, attitude, accelerations etc. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-03-26T11:14:18.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13526" PostTypeId="1" AcceptedAnswerId="13528" CreationDate="2015-03-26T11:28:51.363" Score="20" ViewCount="8414" Body="&lt;p&gt;It would seem reasonable on large commercial airlines to require that there be two people in the cockpit at all times. For example when the pilot goes to the toilet a member of the cabin crew must enter the cockpit until the pilot's return. Such a rule would greatly reduce the probability of pilots being locked out and reduce problems should they be locked out. Do any airlines enforce such a rule? &lt;/p&gt;&#xA;" OwnerUserId="7827" LastEditorUserId="97" LastEditDate="2015-03-26T18:35:25.300" LastActivityDate="2015-03-27T23:37:20.400" Title="Are two people required in cockpit at all times on large commercial aircraft?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;security&gt;&lt;cockpit&gt;&lt;crew&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13527" PostTypeId="1" AcceptedAnswerId="13531" CreationDate="2015-03-26T11:37:26.607" Score="13" ViewCount="2007" Body="&lt;p&gt;If there were nobody at the controls what kind of vertical profile could be expected from, for example, a modern airliner? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After reaching the cruise altitude I assume the pilot just sets a nav route and altitude on the onboard computer or at least set the trim to avoid having to constantly adjusting the altitude manually.&lt;/p&gt;&#xA;" OwnerUserId="7828" LastEditorUserId="64" LastEditDate="2015-03-27T05:10:17.663" LastActivityDate="2015-03-29T15:08:50.110" Title="What vertical flight profile could be expected from an aircraft if the pilots were incapacitated?" Tags="&lt;navigation&gt;&lt;altitude&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13528" PostTypeId="2" ParentId="13526" CreationDate="2015-03-26T11:41:39.400" Score="16" Body="&lt;p&gt;&lt;strong&gt;EDIT: please see at the bottom of the answer the update from EASA&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Are two people required in cockpit at all times on large commercial aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;No.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/Annexes%20to%20Regulation.pdf&quot; rel=&quot;noreferrer&quot;&gt;EASA, pag. 101-102&lt;/a&gt;: (emphasis mine)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;CAT.OP.MPA.210 Crew members at stations&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Flight crew members&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;During take-off and landing each flight crew member required to be on duty in the flight crew compartment shall be at the assigned station.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;During all other phases of flight each flight crew member required to be on duty in the flight crew compartment shall remain at the assigned station, &lt;strong&gt;unless absence is necessary for the performance of duties in connection with the operation or for physiological needs, provided at least one suitably qualified pilot remains at the controls of the aircraft at all times&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;During all phases of flight each flight crew member required to be on duty in the flight crew compartment shall remain alert. If a lack of alertness is encountered, appropriate countermeasures shall be used. If unexpected fatigue is experienced, a controlled rest procedure, organised by the commander, may be used if workload permits. Controlled rest taken in this way shall not be considered to be part of a rest period for purposes of calculating flight time limitations nor used to justify&#xA;any extension of the duty period.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Do any airlines enforce such a rule?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/13544/1467&quot;&gt;other answers&lt;/a&gt; mention, yes.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; On the 27th March 2015 EASA has issued the following &lt;a href=&quot;http://ad.easa.europa.eu/ad/2015-04&quot; rel=&quot;noreferrer&quot;&gt;Safety Information Bulletin&lt;/a&gt; :&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;operators are recommended to implement procedures requiring at least two persons authorised in accordance with CAT.GEN.MPA.135 to be in the flight crew compartment at all times, or other equivalent mitigating measures to address risks identified by the operator’s revised assessment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This still does not mean that 2 people are required, but are recommended.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-27T17:23:08.487" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="13531" PostTypeId="2" ParentId="13527" CreationDate="2015-03-26T11:54:59.720" Score="15" Body="&lt;p&gt;Emergency descent (like during a decompression event where you need to get from cruise to 10k ft ASAP to make sure the people in the back survive) shouldn't make a nice curve. It only wastes time you don't really have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal operation means the pilot activates the autopilot during cruise which will fly the programmed course set by the pilot. It will stay follow that course (or put itself in a holding pattern on the final fix) until it runs out of fuel or the pilot intervenes when it is cleared for descent. This happened with &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot;&gt;Helios Airways Air flight 522&lt;/a&gt;; both pilots were incapacitated shortly after ascent and the plane put itself in a hold and crashed when it ran out of fuel after more than an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A plane where there is nothing controlling the altitude (when control is lost due to loss of hydraulics for example) will follow a &lt;a href=&quot;https://en.wikipedia.org/wiki/Phugoid&quot;&gt;phugoid cycle&lt;/a&gt;. That is a series of dives and climbs as the elevators gain and lose bite on the air with speed.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-03-26T13:28:44.190" LastActivityDate="2015-03-26T13:28:44.190" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13533" PostTypeId="1" AcceptedAnswerId="13542" CreationDate="2015-03-26T12:14:40.380" Score="7" ViewCount="863" Body="&lt;p&gt;Is it plausible for a pilot inside the cockpit to be incapacitated and that at the same time the pilot locked outside simply doesn't remember the code or the procedure for entering the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="7830" LastEditorUserId="1696" LastEditDate="2015-03-26T15:49:08.820" LastActivityDate="2015-03-26T15:53:18.537" Title="Is it plausible to forget the cockpit unlocking code?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13534" PostTypeId="1" AcceptedAnswerId="13535" CreationDate="2015-03-26T12:26:47.127" Score="66" ViewCount="6078" Body="&lt;p&gt;There are multiple switches and buttons in the cockpit, with different shapes and layouts. Are they spill proof? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What if the pilot spills water or coffee on them, will they still function?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="15982" LastEditDate="2017-06-01T15:01:03.270" LastActivityDate="2020-08-18T09:23:16.493" Title="Are the instrument panels in the cockpit spill / waterproof?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;cockpit&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13535" PostTypeId="2" ParentId="13534" CreationDate="2015-03-26T12:32:41.910" Score="43" Body="&lt;p&gt;No they are not, at least not fully. There have been instances of equipment failure caused by coffee spills, resulting in the need to abort the flight.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=435ad471&quot; rel=&quot;noreferrer&quot;&gt;This example&lt;/a&gt; shows a flight that needed to divert because a coffee spill disabled the communication equipment.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation-safety.net/database/record.php?id=19850815-0&amp;amp;lang=en&quot; rel=&quot;noreferrer&quot;&gt;This Boeing 707&lt;/a&gt; had to make an emergency landing after the crew inadvertently spilled water on the autopilot panel causing the stabilizer trim wheel started to rotate. Control was lost as the plane pitched up and down. Three people died in the accident.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=3f382ded&quot; rel=&quot;noreferrer&quot;&gt;This Boeing 737&lt;/a&gt; &lt;sup&gt;&lt;a href=&quot;https://taic.org.nz/sites/default/files/inquiry/documents/07-004vFINAL.pdf&quot; rel=&quot;noreferrer&quot;&gt;report&lt;/a&gt;&lt;/sup&gt; had smoke in the cockpit because the previous flight crew spilled coffee and sugar over the avionics.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief.aspx?ev_id=63721&amp;amp;key=0&quot; rel=&quot;noreferrer&quot;&gt;This Boeing 720&lt;/a&gt; suffered control problems (resulting in Dutch roll) after a coffee spill cause a short circuit in the yaw damper.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=4c3da991&amp;amp;opt=0&quot; rel=&quot;noreferrer&quot;&gt;This Airbus A330&lt;/a&gt; diverted for an emergency landing after liquid was spilled onto electronic devices in the cockpit causing the smoke.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pd50t.png&quot; alt=&quot;Burned electrics&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Source: Transport Accident Investigation Commission of New Zealand&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2020-08-18T09:23:16.493" LastActivityDate="2020-08-18T09:23:16.493" CommentCount="17" ContentLicense="CC BY-SA 4.0" />
  <row Id="13536" PostTypeId="2" ParentId="13527" CreationDate="2015-03-26T12:41:20.867" Score="5" Body="&lt;p&gt;Large commercial aircraft are not expected to descend if their pilots just walk way. At least, not quickly. Large planes generally cruise on autopilot, which will keep altitude until told otherwise. In fact, airliners generally have flight management computers that will fly the entire route before holding near the destination. When the plane runs out of fuel,  it will slow down and then, finally, it will descend until it crashes. This was seen in Helios 522. I don't know what that descent profile would look like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://cfapp.icao.int/fsix/sr/reports/05002960_final_report.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helios 522 accident report&lt;/a&gt; shows the following&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/s40Ns.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft enters from bottom right. AP lines up aircraft with Athens International airport  runway. after overflying airport, AP turns SE and puts aircraft on holding pattern (loop at bottom). Fuel exhaustion causes one engine to flame out and AP to disengage. Aircraft starts to bank (assymetric thrust) and turns. Second engine flames out. Final descent is on a roughly spiral track. &lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="1289" LastEditDate="2015-03-26T16:48:56.360" LastActivityDate="2015-03-26T16:48:56.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13537" PostTypeId="2" ParentId="13527" CreationDate="2015-03-26T12:58:03.033" Score="5" Body="&lt;p&gt;Any descent profile can be expected of an unpiloted aircraft, but generally nothing severe would be expected uncommanded and without stall occuring. Aircraft control surfaces (rudder, elevator, aileron) can be &quot;trimmed&quot; to maintain coordinated level flight.  Elevator trim, in particular, is constantly adjusted (by the pilot or autopilot) so that if nothing was flying the plane it would maintain its present airspeed.  A consequence of this is that a properly trimmed airplane will climb or descent to maintain the airspeed it is trimmed for.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Give the above we can say a properly trimmed aircraft with no pilot input could be expected to roughly maintain altitude and once out of fuel it will descend at whatever rate is required to maintain its trimmed airspeed.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above assumes no autopilot or an autopilot in speed hold mode.  An autopilot in altitude hold mode will attempt to maintain altitude as long as possible, and depending on the programming that might mean until stall occurs.  When the stick shaker activates preceding the stall, that should disconnect the autopilot and this may be followed by stick pusher activation.  In the end, if stall is avoided, the airplane will descend at the airspeed that autopilot last trimmed it for, which is likely a slow-ish airspeed (close to but above stall speed at present altitude).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-03-26T12:58:03.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13538" PostTypeId="2" ParentId="13509" CreationDate="2015-03-26T14:04:00.290" Score="1" Body="&lt;p&gt;Similar to several other terms (e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Port_and_starboard#Use_in_aviation&quot; rel=&quot;nofollow&quot;&gt;port and starboard&lt;/a&gt;), the logging formats came from the shipping industry. Ship used to have detailed logs about their voyages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smithsonian states &lt;a href=&quot;http://www.airspacemag.com/history-of-flight/the-book-of-hours-136493265/#ixzz3VV0YO2Na&quot; rel=&quot;nofollow&quot;&gt;in an article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In a logbook from 1913, a pilot penned on one page the date of a&#xA;  flight, airplane used, passenger’s name, time aloft, and course flown.&#xA;  On the opposite page, he recorded height achieved, distance, weather,&#xA;  and remarks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The above-mentioned article also tells:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Wright brothers kept detailed notebooks, recording dispassionately&#xA;  the results of their experiments in building the first airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the US, pilots are required to document their flights in logbooks (&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.51&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51&lt;/a&gt;). I doubt that logbooks would be optional anywhere in the world. In fact, if you do not log your flight, it is your loss more than anyone else's.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-26T14:04:00.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13540" PostTypeId="2" ParentId="13385" CreationDate="2015-03-26T15:25:47.550" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1898/1696&quot;&gt;Curved runways&lt;/a&gt; have many issues. Especially in bad weather, &lt;a href=&quot;http://avherald.com/h?article=482b659f&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft sometimes run off of straight runways&lt;/a&gt;, so a curved one would be even harder to stay on. The curve would also increase the distance needed for both takeoff and landing, meaning that even more than 2 miles would be needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/9980/1696&quot;&gt;Sloped runways do exist&lt;/a&gt;. However, sloped runways like &lt;a href=&quot;http://www.gcmap.com/airport/EPZR&quot; rel=&quot;nofollow noreferrer&quot;&gt;EPZR&lt;/a&gt; (&lt;a href=&quot;https://aviation.stackexchange.com/a/13386/1696&quot;&gt;mentioned by Peter Kämpf&lt;/a&gt;) or &lt;a href=&quot;http://en.wikipedia.org/wiki/Tenzing-Hillary_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lukla&lt;/a&gt; tend to be small (both are less than 2000 feet, EPZR is not paved). The physics limit the runway to operating in one direction only. Though wind becomes less of a factor, the issues still prevent this from being used for large airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue is the height of the high end of the runway. Zar and Lukla are both located in terrain that requires one end of the runway to be raised. A 1-mile square island would probably not be shaped this way. Even if it is, if an airplane goes off the runway, or needs to abort a takeoff or landing, the slope will make this much harder. The pilots would also have to adjust their takeoff and landing technique to account for the slope, which will probably result in many more hard landings and tail strikes. A sloped runway may be acceptable for small aircraft and short runways, but typical aircraft needing 2 miles of runway will be much more difficult to operate this way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft carriers solve the runway length issue with a &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_deck#Ski-jump_ramp&quot; rel=&quot;nofollow noreferrer&quot;&gt;slope only one the very end&lt;/a&gt;. However, this is most helpful to aircraft like the &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Aerospace_Sea_Harrier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Harrier&lt;/a&gt; that already can provide some vertical thrust, and the aircraft must still perform an arrested landing. &lt;a href=&quot;http://en.wikipedia.org/wiki/CATOBAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;Other carriers use a steam catapult&lt;/a&gt; to assist takeoff, which requires much more maintenance but is capable of launching heavier aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a sea plane to land on the water is another option. However, aircraft on the scale of needing a 2 mile runway are &lt;a href=&quot;http://en.wikipedia.org/wiki/Hughes_H-4_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;typically&lt;/a&gt; not sea planes. If you are going to design a new plane, you might as well design one that can operate to the runway length requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another fun option is jet-assisted takeoff (&lt;a href=&quot;http://en.wikipedia.org/wiki/JATO&quot; rel=&quot;nofollow noreferrer&quot;&gt;JATO&lt;/a&gt;). Rocket engines are strapped to the plane to accelerate it to takeoff speed more quickly. These can be used for landing as well, but that is &lt;a href=&quot;http://en.wikipedia.org/wiki/Operation_Credible_Sport&quot; rel=&quot;nofollow noreferrer&quot;&gt;a bit more difficult&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do to the issues with these options, large airports in need of land tend to just make more land. You can put an entire airport with runways &gt;2 miles long on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Hong_Kong_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;completely man-made island&lt;/a&gt;. There is typically enough room around an island that creating an extension is not an issue.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-26T15:25:47.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13541" PostTypeId="2" ParentId="13526" CreationDate="2015-03-26T15:43:26.663" Score="2" Body="&lt;p&gt;The FAA has very similar rules about flight crewmembers leaving their station.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.3.121_1543&quot; rel=&quot;nofollow noreferrer&quot;&gt;§121.543   Flight crewmembers at controls.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(b) A required flight crewmember &lt;strong&gt;may leave the assigned duty station&lt;/strong&gt;—&lt;/p&gt;&#xA;&lt;p&gt;(1) If the crewmember's absence is necessary for the performance of duties in connection with the operation of the aircraft;&lt;/p&gt;&#xA;&lt;p&gt;(2) If the crewmember's absence is in connection with physiological needs; or&lt;/p&gt;&#xA;&lt;p&gt;(3) If the crewmember is taking a rest period, and relief is provided—...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It goes on to describe the requirements of a relief crewmember, but this is only if the pilot is taking a &amp;quot;rest period&amp;quot;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-26T18:36:24.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13542" PostTypeId="2" ParentId="13533" CreationDate="2015-03-26T15:53:18.537" Score="4" Body="&lt;p&gt;The code would also be shared among the purser and/ or the other flight attendants, so the answer is no. I believe however that they tend to keep the same code for a few days within the same crew to make remembering it easier.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-03-26T15:53:18.537" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13543" PostTypeId="2" ParentId="13401" CreationDate="2015-03-26T15:53:26.773" Score="3" Body="&lt;p&gt;Right after takeoff bleed air would be necessary to restart, preferably from the APU if thrust reduction on the operating engine is unacceptable in the current phase of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I only have data for the Rolls Royce Allison AE3007 A series engines and the windmilling envelope at all altitudes is between 260 KIAS and Vmo/Mmo with the additional limitation that N2 must be above 10%.  An aircraft that has just taken off will not be going this fast so an assisted (bleed air) start is the only viable option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long the start will take depends on the particular engine, but all turbines (that I'm aware of) have a maximum start time limitation.  The engine discussed above on the EMB-145 has a 60 second limitation on starting.  Based upon my experience starting the engines with a stiff headwind, I'd assume that an APU start at flying speeds would probably take around 35-40 seconds in the EMB-145.  By the book the engine needs another minute before significant thrust is applied.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the above information is specific to one airframe/engine combination and will vary for other aircraft and engines. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-03-26T15:53:26.773" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13544" PostTypeId="2" ParentId="13526" CreationDate="2015-03-26T16:31:09.697" Score="9" Body="&lt;p&gt;It's not required by a regulation, but, yes, it is required by the procedures of some airlines, at least in the U.S.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A flight attendant taking the seat of an absent pilot to ensure there are always two people in the cockpit, and/or blocking access to the open door with a trolley, are often seen on US flights, but not necessarily on others, Hansford said. For instance it is not a requirement on Australian flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.theguardian.com/world/2015/mar/26/germanwings-crash-safety-of-cockpit-doors-on-all-planes-questioned&quot;&gt;http://www.theguardian.com/world/2015/mar/26/germanwings-crash-safety-of-cockpit-doors-on-all-planes-questioned&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also heard numerous U.S. airline passengers claim to have witnessed this frequently, though I don't recall having seen it personally.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-03-26T16:42:36.090" LastActivityDate="2015-03-26T16:42:36.090" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13545" PostTypeId="1" AcceptedAnswerId="13549" CreationDate="2015-03-26T16:40:06.143" Score="19" ViewCount="5078" Body="&lt;p&gt;The air intake on a fanjet typically has many small angled blades. A wind pump in an American film might have many broad slatted blades. My desk fan has 3 very large scooping blades and seems quite effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to me that if each blade provides thrust, the more blades you have, the more thrust you might expect. It also seems to me that a propeller with more blades could be smaller and turn more slowly, potentially avoiding going supersonic while providing the same level of thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I ask because I'm building a drone and considering using six small multibladed props.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the downsides of adding more blades to propellers?&lt;/p&gt;&#xA;" OwnerUserId="1401" LastEditorUserId="1401" LastEditDate="2015-03-29T20:57:59.043" LastActivityDate="2016-12-04T00:28:07.817" Title="Why don't aeroplanes use propellers with more blades like the intake on a fanjet?" Tags="&lt;propeller&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13546" PostTypeId="2" ParentId="13534" CreationDate="2015-03-26T16:52:58.377" Score="18" Body="&lt;p&gt;On the old Zeppelins all electrical switches were enclosed, with the actual switching contacts submerged in oil to avoid sparks. And Zeppelins had a lot of switches, containing much more electrical equipment than typical aircraft of their times. All these switches were also spill-proof by design. Airship engineering seems to be a lost art ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RVtP4.jpg&quot; alt=&quot;Left: Radio operator of a WW I Zeppelin at his equipment, right: Elektroraum of the LZ 127&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Left: Radio operator of a WW I Zeppelin at his equipment, right: Elektroraum of the LZ 127.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T09:04:01.713" LastActivityDate="2015-05-10T09:04:01.713" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13547" PostTypeId="1" CreationDate="2015-03-26T16:55:11.913" Score="20" ViewCount="8242" Body="&lt;p&gt;I've occasionally read about &lt;a href=&quot;http://www.cnn.com/2015/01/30/travel/feat-delta-captain-lockout/&quot;&gt;pilots being locked out of the cockpit&lt;/a&gt; in flight, and was wondering:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why might a pilot leave the cockpit during a short flight (1-2 hours)?&lt;/p&gt;&#xA;" OwnerUserId="7840" LastEditorUserId="64" LastEditDate="2015-03-26T17:55:32.217" LastActivityDate="2016-01-09T13:51:37.403" Title="Why pilots would leave the cockpit in a short flight?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13548" PostTypeId="2" ParentId="13547" CreationDate="2015-03-26T17:01:30.550" Score="42" Body="&lt;p&gt;The cockpit of some airliners lacks a lavatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationknowledge.wikidot.com/aviation:cockpit-airplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/whn6M.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Cockpit layout from AviationKnowledge.wikidot&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is discussed in &lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Deck_Security&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skybrary: Flight Deck Security&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Locked Door Flight Safety Issues&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  Physiological Need. Naturally, the need for flight crew to use toilets, access designated crew rest facilities or be supplied with food and drink, requires access through the flight deck door during flight. Procedures for door opening mean that egress and access will take longer with the result that the flight deck crew are not always able to go to the toilet at a time of their exact choice, which may cause them to be distracted and, exceptionally, might exacerbate an existing underlying medical issue in a way that would not otherwise have occurred.&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  Longer term, design change could also ensure that all operating flight crew should be secured on the flight-deck before the passenger boarding doors are closed prior to departure and remain secured on the flight-deck until after the passenger doors are opened at the destination. This would prevent any unlawful entry from the cabin and minimise any unlawful seizure by a single flight crew member.&lt;br&gt;&#xA;  To enable this, existing aircraft could be modified and new aircraft designed with all required crew facilities forward of the secure flight-deck door. On short/medium haul aircraft this would require a toilet, safe food &amp;amp; water storage and a reclining crew rest seat. Additionally on aircraft used for long range operations where in-flight relief is required provision of bunk/s.&#xA;  This is not a new concept, many long range aircraft already have toilet and crew rest facilities forward of the secure flight-deck door.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-01-09T13:51:37.403" LastActivityDate="2016-01-09T13:51:37.403" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="13549" PostTypeId="2" ParentId="13545" CreationDate="2015-03-26T17:05:12.777" Score="16" Body="&lt;p&gt;Every blade will create its own boundary layer and its own vortex sheet. It is more efficient to use fewer blades with deeper chord, because the forward part of a boundary layer contributes most to friction drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To keep the lift coefficient on the propeller blade sections in a reasonable range (0.6 to 1.0) for efficiency means that blade chord will be reduced, which will make them less stiff. Again, it will be better to reduce blade count to arrive at a more viable design. All the thrust the propeller creates is pulling on those skinny blades, and they must be strong enough to withstand this force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only when the propeller disc loading increases do more blades begin to make sense:&lt;br&gt;&#xA; When engine power increases, the propeller disc area should also grow, but this growth is limited by the resulting speed of the blade tips. Once the flow speed there becomes supersonic, the drag at this section of the blade increases without a corresponding increase in thrust. To avoid that the next best option is to increase the solidity ratio of the propeller, called also the &lt;a href=&quot;http://quest.arc.nasa.gov/qna/questions/Propellers_Activity_Factor.htm&quot;&gt;activity ratio&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make no mistake, this is bad for efficiency. But if there is enough power available, adding more blades is the best way out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right, a lower prop speed allows to increase its diameter, but while tip speed will drop by less than the reduction in prop speed (after all, flight speed should not change), the available thrust from this propeller will drop by the square of the speed reduction, since thrust is proportional to the dynamic pressure on the blades. And thrust you get only from the circumferential fraction of the local speed at the blade; flight speed does not count here and does not help to mitigate the reduction.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-27T21:32:44.983" LastActivityDate="2015-03-27T21:32:44.983" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13550" PostTypeId="1" CreationDate="2015-03-26T19:08:33.510" Score="2" ViewCount="1328" Body="&lt;p&gt;Is it possible to convert a commercial airplane into a drone, such that if a pilot fails to respond to ATC it can be remotely piloted?&lt;/p&gt;&#xA;" OwnerUserId="7842" LastEditorUserId="2171" LastEditDate="2015-03-27T12:33:50.307" LastActivityDate="2015-05-03T23:18:46.277" Title="Can commercial airplanes be converted to drones?" Tags="&lt;commercial-aviation&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13552" PostTypeId="2" ParentId="13550" CreationDate="2015-03-26T19:22:14.030" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible to convert a Commercial Airplane into a Drone&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For what its worth, yes this would be technically possible however it comes with some risks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When To Take Control:&lt;/strong&gt; This brings into the simple idea that in an emergency the pilot may need to be in control of the situation as they often have the most information about exactly what is happening. If the plane had a serious issue and the ground controller did not know what was happening they may take control and only exacerbate the problem.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Connection Reliability:&lt;/strong&gt; Keep in mind that planes are flying at very high altitudes moving quite fast. Maintaining a reliable connection in these conditions is difficult. Since a reliable connection is hard enough to maintain you again may create more issues than you solve. This also has to be a fully duplexed channel since the plane needs to transmit its telemetry and receive control inputs in what is more or less real time. At this point the data up/down rates would push the limits of what we can do today.     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Connection Security:&lt;/strong&gt; As mentioned you would need to secure the connection to prevent someone from taking it over maliciously. This in and of its self is a big problem. But lets not turn this into a digital security debate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cost:&lt;/strong&gt; As nice as safety is its not free. Since there is currently no system in place on a global scale to do this it would have to be created. Someone has to pay for that and unless the FAA is going to require it you will have to get the airlines/aircraft makers on board with this voluntarily. On top of that any system that is added like this would have to be certified by the FAA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while it is possible there are very real barriers to a system like this include but are not limited to the ones listed above and before someone comes back with the &quot;if it makes it safer than we should spend the time figuring it out&quot; response I will mention that modern technology is as good as it is and there are already companies and individuals researching new tech like this but Keep in mind that with FAA regulations taking the time they do to get, planes are flying with tech that is now considered &quot;dated&quot; by the tech world.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-03-26T19:22:14.030" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13553" PostTypeId="2" ParentId="13550" CreationDate="2015-03-26T19:23:01.730" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible to convert a Commercial Airplane into a Drone?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Techical feasibility is just one aspect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's start from what is a Drone nowadays: it is a remotely controlled aircraft.&#xA;This means that to &quot;convert&quot; a commercial aircraft into a drone you need:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;a pilot on ground&lt;/li&gt;&#xA;&lt;li&gt;bi-directional communication&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Bi-directional communication is the &quot;easy&quot; part: plug in a bi-directiona antenna, write some thousand lines of code to make it usable within the aircraft system, spend years and tons of money to certify the new components and the code and you're good to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need qualified personnel on ground continuously on stand-by, something that is going to cost (and is not given that it will popular).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now let me add a second part:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Would it be useful?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is not given, by reading the few official informations available ATC had no idea about the situation on board in those 8 minutes, it is not given that such a system would have been activated.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Should it be done?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would say that the benefits are  dubious at best: you're opening a channel &lt;strong&gt;on every aircraft&lt;/strong&gt; that allows them to be controlled remotely. Someone is gonna try to crack whatever encryption is going to be used, with results much worse than the original &quot;problem&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-03-26T19:23:01.730" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13554" PostTypeId="1" CreationDate="2015-03-26T19:23:17.420" Score="9" ViewCount="837" Body="&lt;p&gt;I am a student pilot in Australia. Someone said he saw me fly into a cloud at 1700 feet above ground level for five seconds. But I am sure I did not fly in the cloud. I have no instrument rating, nor a pilot license yet. I am grounded and waiting for further investigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What punishment will I get from CASA if it rules I flew through a cloud?&lt;/p&gt;&#xA;" OwnerUserId="7846" LastEditorUserId="7850" LastEditDate="2015-03-26T21:57:39.837" LastActivityDate="2015-03-27T04:24:13.073" Title="What punishment will I get from CASA if I fly in a cloud while a student pilot?" Tags="&lt;visual-flight-rules&gt;&lt;casa-regulations&gt;&lt;vmc&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13555" PostTypeId="2" ParentId="13550" CreationDate="2015-03-26T19:24:41.443" Score="3" Body="&lt;p&gt;&lt;strong&gt;Is it possible to convert a Commercial Airplane into a Drone?&lt;/strong&gt;&lt;br&gt;&#xA;&lt;em&gt;Yes&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Can it be done at will?&lt;/strong&gt;&lt;br&gt;&#xA;&lt;em&gt;Not likely&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has &lt;a href=&quot;http://www.boeing.com/advertising/support/_maintenance/QF-16.html&quot; rel=&quot;nofollow&quot;&gt;converted an F-16&lt;/a&gt; into an unmanned drone (&lt;a href=&quot;http://www.gizmag.com/boeing-f16-jet-unmanned-drone/29203/&quot; rel=&quot;nofollow&quot;&gt;some pictures here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that it cannot be done just by the push of a button, in a case similar to the Germanwings airplane. A drone costs a lot of money, and fitting &lt;em&gt;every&lt;/em&gt; airplane with such technology is not feasible.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-03-26T19:24:41.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13556" PostTypeId="2" ParentId="13550" CreationDate="2015-03-26T19:26:46.810" Score="7" Body="&lt;p&gt;In order to prevent both incidents such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot;&gt;Malaysia 370&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Germanwings_Flight_9525&quot;&gt;Germanwings 9525&lt;/a&gt;, you would need a system that could have &lt;em&gt;immediate and complete control of the plane,&lt;/em&gt; as well as &lt;em&gt;impossible to be disabled by the crew.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the other reasons offered, this sounds like it would be a bad thing more often than it would help. Is the plane allowed to fly if it is not working? Who decides when to take over control? ATC? &lt;a href=&quot;http://en.wikipedia.org/wiki/Chicago_Air_Route_Traffic_Control_Center&quot;&gt;Do we trust that whole system?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-03-26T19:26:46.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13559" PostTypeId="2" ParentId="13547" CreationDate="2015-03-26T20:06:11.753" Score="24" Body="&lt;p&gt;The FAA provides the following reasons for which a pilot is allowed to leave their assigned duty station (i.e. their seat in the flight deck) in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.3.121_1543&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §121.543 Flight crewmembers at controls&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) A required flight crewmember may leave the assigned duty station—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) If the crewmember's absence is necessary for the performance of duties in connection with the operation of the aircraft; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) If the crewmember's absence is in connection with physiological needs; or &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) If the crewmember is taking a rest period, and relief is provided—&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Case #3 generally applies only to long-haul flights where one or two relief pilots will alternate duty with the initial pilots, allowing each of them to have a rest period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Europe's EASA has similar regulations. See &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/Annexes%20to%20Regulation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAT.OP.MPA.210 in this document&lt;/a&gt; (on pages 101-102).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CAT.OP.MPA.210 Crew members at stations&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Flight crew members&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) During take-off and landing each flight crew member required to be on duty in the flight crew compartment shall be at the assigned station.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) During all other phases of flight each flight crew member required to be on duty in the flight crew compartment shall remain at the assigned station, unless absence is necessary for the performance of duties in connection with the operation or for physiological needs, provided at least one suitably qualified pilot remains at the controls of the aircraft at all times.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, in summary, a pilot can leave the flight deck on short flights if:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The pilot needs to go to the bathroom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) The pilot needs to perform some action relevant to flying the plane (such as going to the back to physically inspect some part of the plane, like in &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_32&quot; rel=&quot;nofollow noreferrer&quot;&gt;QF32&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_811&quot; rel=&quot;nofollow noreferrer&quot;&gt;United 811&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related question whose answers also mentions these regs: &lt;a href=&quot;https://aviation.stackexchange.com/q/13526/755&quot;&gt;Are two people required in the cockpit at all times on large commercial aircraft?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-26T20:41:09.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13560" PostTypeId="2" ParentId="13550" CreationDate="2015-03-26T20:32:31.080" Score="1" Body="&lt;p&gt;Can you if you prepare for it? Yes, it's been done for both full scale crash tests &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_Impact_Demonstration&quot; rel=&quot;nofollow&quot;&gt;NASA's controlled impact demonstration&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment&quot; rel=&quot;nofollow&quot;&gt;boeing's crash experiment&lt;/a&gt;; the final leg of the flights was done remotely both times (you don't want a pilot in there for longer than you need to).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It requires modification of the aircraft to decode the radio signals into control inputs. But the existing auto pilot will help a lot. Doing so remotely in mid-flight is flat out impossible.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-03-26T20:39:00.403" LastActivityDate="2015-03-26T20:39:00.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13561" PostTypeId="1" AcceptedAnswerId="13564" CreationDate="2015-03-26T21:01:03.607" Score="18" ViewCount="3683" Body="&lt;p&gt;I am aware a lot of psychological tests are given to pilots to prevent such a scenario, but those can hardly be perfect, so has any aviation accident been caused (or attempted) by the conscious intention of one of the crew?&lt;/p&gt;&#xA;" OwnerUserId="1368" LastEditorUserId="1677" LastEditDate="2015-03-28T00:06:50.767" LastActivityDate="2015-03-28T06:10:44.313" Title="Has any prior accident been caused by a psychologically unstable and/or suicidal crew member?" Tags="&lt;accidents&gt;&lt;pilots&gt;&lt;crew&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13562" PostTypeId="2" ParentId="13561" CreationDate="2015-03-26T21:13:04.817" Score="9" Body="&lt;ul&gt;&#xA;&lt;li&gt;EgyptAir 990&lt;/li&gt;&#xA;&lt;li&gt;SilkAir 185&lt;/li&gt;&#xA;&lt;li&gt;JAL 350&lt;/li&gt;&#xA;&lt;li&gt;LAM Mozambique 470&lt;/li&gt;&#xA;&lt;li&gt;Royal Air Maroc 630&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Those are 5 I found in very little searching. Some of them are disputed (e.g. Egypt's aviation authority maintains EgyptAir was a mechanical issue, the NTSB determined it was intentionally crashed), but these have all been identified by investigators as probable intentional crashes by flight crew. This would be far from the first time this happened. In LAM Mozambique, the copilot was locked out of the cockpit. In EgyptAir 990, the relief first officer did it when the captain stepped out; the captain made it back in but couldn't regain control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for attempts, Fedex 705 is a notable attempt by an off-duty second officer deadheading on a Fedex plane to hijack the plane and crash it into Fedex headquarters. &lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-03-26T21:13:04.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13563" PostTypeId="1" CreationDate="2015-03-26T21:47:58.470" Score="3" ViewCount="411" Body="&lt;p&gt;Are there sensors that can detect a rip, crack or damage in the fuselage skin by not using air pressure differential on aircraft? &lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="3386" LastEditDate="2015-03-27T02:23:34.150" LastActivityDate="2015-03-27T18:24:26.603" Title="Do fuselage rip/crack/damage sensors exist?" Tags="&lt;safety&gt;&lt;fuselage&gt;&lt;sensors&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13564" PostTypeId="2" ParentId="13561" CreationDate="2015-03-26T21:58:18.483" Score="45" Body="&lt;h2&gt;Confirmed (or Highly Probable)&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/LAM_Mozambique_Airlines_Flight_470&quot; rel=&quot;nofollow noreferrer&quot;&gt;LAM Mozambique Airlines Flight 470&lt;/a&gt;:&lt;/strong&gt; A report from the government of Mozambique states that &lt;a href=&quot;http://www.aljazeera.com/news/africa/2013/12/pilot-deliberately-caused-namibia-crash-201312225824891819.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;the captain deliberately crashed an Embraer 190&lt;/a&gt; in Namibia on November 29, 2013. Cockpit voice recorders were the primary evidence in the report, which found that the other crew members were locked out of the cockpit by the captain. There were 33 fatalities, and Mozambique Airlines was banned from flying in EU airspace. No psychological overview was done of the officer.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/EgyptAir_Flight_990&quot; rel=&quot;nofollow noreferrer&quot;&gt;EgyptAir Flight 990&lt;/a&gt;&lt;/strong&gt;: A Boeing 767 crashed near Nantucket (Massachusetts) on October 31, 1999, killing 217 people. It was found that &lt;a href=&quot;http://en.wikipedia.org/wiki/Gameel_Al-Batouti&quot; rel=&quot;nofollow noreferrer&quot;&gt;the first officer&lt;/a&gt;, was responsible. &lt;a href=&quot;http://wayback.archive.org/web/20110604054854/http://www.ntsb.gov/events/EA990/docket/Ex_2A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The NTSB&lt;/a&gt; and &lt;a href=&quot;http://wayback.archive.org/web/20110604061959/http://www.ntsb.gov/events/ea990/docket/ecaa_report.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Egyptian Civil Aviation Authority&lt;/a&gt; both conducted individual investigations. The Egyptian report states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[the] First Officer . . . passed his full medical examination and psychiatric&#xA;  assessment, which was performed by the Egyptian Air Force Medical Council as part of his full medical examination for fitness to be a pilot in the Egyptian Air Force, on December 11, 1958. He passed his medical examination for his Commercial Pilot license on July 27, 1961. A psychiatric assessment was not conducted as part of the medical examination for the relief first officer’s medical review for his Commercial Pilot license. During his military and civilian flying career there was no reported history of psychiatric consultation nor any reports regarding his behavior, either professionally or in groups.&#xA;  . . .&#xA;  First, there is no evidence to support a conclusion that the First Officer intentionally dove the airplane into 142 the ocean in fact, the evidence available refutes such a theory, a determination confirmed by expert medical opinion, technical and human performance analysis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The NTSB did not agree that the most probable cause was a mechanical failure. Their conclusions, and the relevant rebuttals by the Egyptian investigators, can also be found &lt;a href=&quot;http://www.webcitation.org/5zlFg31jj&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/SilkAir_Flight_185&quot; rel=&quot;nofollow noreferrer&quot;&gt;SilkAir Flight 185&lt;/a&gt;&lt;/strong&gt;: On December 19, 1997, a 737 operated by SilkAir crashed in Indonesia, killing all 104 people on board. The aircraft was almost entirely obliterated. &lt;a href=&quot;http://www.dephub.go.id/knkt/ntsc_aviation/Revised-MI185%20Final%20Report%20(2001).pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Indonesian NTSC report&lt;/a&gt; (link broken at the moment) said that the cause was impossible to determine. &lt;a href=&quot;http://web.archive.org/web/20070323224159/http://www2.mha.gov.sg/mha/detailed.jsp?artid=375&amp;amp;type=4&amp;amp;root=0&amp;amp;parent=0&amp;amp;cat=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;The pilot appeared to be mentally stable&lt;/a&gt;, but there have been some doubts. Cockpit recorders stopped at some time, making the case different from that of, say, JetBlue Airways Flight 191 (see below). &lt;a href=&quot;http://web.archive.org/web/20090227095056/http://www.casa.gov.au/fsa/2008/feb/18-28.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The NTSB was not happy&lt;/a&gt;, severely criticizing the Indonesian findings. Their analysis seem to rule out mechanical issues.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Royal_Air_Maroc_Flight_630&quot; rel=&quot;nofollow noreferrer&quot;&gt;Royal Air Marco Flight 630&lt;/a&gt;&lt;/strong&gt;: 44 people were killed in a crash in Morocco on August 24, 1994. &lt;a href=&quot;https://news.google.com/newspapers?id=OwJCAAAAIBAJ&amp;amp;sjid=caoMAAAAIBAJ&amp;amp;pg=1754,6528136&amp;amp;dq=air+maroc+suicide&amp;amp;hl=en&quot; rel=&quot;nofollow noreferrer&quot;&gt;A government investigation ruled it an intentional suicide&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_350&quot; rel=&quot;nofollow noreferrer&quot;&gt;Japan Airlines Flight 350&lt;/a&gt;&lt;/strong&gt;: The crash of a DC-8 on February, 1982, &lt;a href=&quot;http://www.airdisaster.com/cgi-bin/view_details.cgi?date=02091982&amp;amp;reg=JA8061&amp;amp;airline=Japan+Air+Lines&quot; rel=&quot;nofollow noreferrer&quot;&gt;was caused by actions taken by the captain&lt;/a&gt; before being restrained by other crew members. Because of their actions, the majority of the people on board survived.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/1999_Air_Botswana_incident&quot; rel=&quot;nofollow noreferrer&quot;&gt;1999 Air Botswana Incident&lt;/a&gt;&lt;/strong&gt;: On October 11, 1999, an Air Botswana pilot deliberately crashed an Aérospatiale ATR-42 into two other planes on the tarmac at Sir Seretse Khama airport, killing only the pilot. He was the only one on board, having taken the plane rogue and then flown it about the airport for hours. All the planes were destroyed, though the other two were unoccupied, as the airport had been effectively shut down. &lt;a href=&quot;http://www.airdisaster.com/cgi-bin/view_details.cgi?date=10111999&amp;amp;reg=A2-ABB&amp;amp;airline=Air+Botswana&quot; rel=&quot;nofollow noreferrer&quot;&gt;The pilot was on medical suspension&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;'Close Calls' but no resultant accidents&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/JetBlue_Airways_Flight_191&quot; rel=&quot;nofollow noreferrer&quot;&gt;JetBlue Airways Flight 191&lt;/a&gt;&lt;/strong&gt;: Midway through the flight, the captain of the aircraft appeared to suffer a nervous breakdown. He began yelling about religion and was eventually subdued by passengers after being locked out of the cockpit by the first officer. He was charged with &quot;interference with a flight crew&quot;, according to &lt;a href=&quot;http://www.fbi.gov/dallas/press-releases/2012/jetblue-pilot-charged-with-interference-with-a-flight-crew&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FBI&lt;/a&gt;, which said&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As the plane was leaving JFK and climbing in altitude in its scheduled five-hour flight, [the captain] said something to the first officer (FO) about being evaluated by someone, but the FO did not know what he meant. [The captain] then talked about his church and the need to “focus” and asked the FO to take the controls and work the radios. [The captain] began talking about religion, but, according to the FO, his statements were not coherent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I also found the same incidences as &lt;a href=&quot;https://aviation.stackexchange.com/questions/13561/has-any-prior-accident-been-caused-by-an-psychologically-unstable-pilot/13562#13562&quot;&gt;cpast&lt;/a&gt;, from &lt;a href=&quot;http://news.yahoo.com/glance-plane-crashes-blamed-deliberate-pilot-action-141825763.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Yahoo! News&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On some of the flights listed, the results of the investigations deemed the pilots obviously mentally unstable. On others, though, the conclusions were disputed, and it may not be possible to truly prove the cases one way or another.&lt;/p&gt;&#xA;" OwnerUserId="7810" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-03-27T18:36:37.453" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="13566" PostTypeId="1" AcceptedAnswerId="13567" CreationDate="2015-03-26T22:33:26.550" Score="18" ViewCount="3118" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2803/can-one-pilot-lock-the-other-out-of-the-cockpit&quot;&gt;Can one pilot lock the other out of the cockpit?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is mentioned in the answer to the question I linked that a person inside the cockpit can stop a person outside from opening the door by &quot;canceling the unlock process&quot;. This leads to several further questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How exactly does the person on the inside &quot;cancel the unlock process&quot; (Press a button, flip a switch, enter &quot;counter code&quot;, etc...)&lt;/li&gt;&#xA;&lt;li&gt;It seems there is a delay before the door opens. Is this correct? What's the duration of the delay?&lt;/li&gt;&#xA;&lt;li&gt;What are the &quot;authority levels&quot; of codes? Which levels exist, what do they mean?&lt;/li&gt;&#xA;&lt;li&gt;What is the confidentiality policy regarding those codes in theory and practice? (Who gets what authority level code officially? If stewards/stewardesses are not allowed to have the codes do pilots usually pass them on anyways?)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7852" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-03-28T13:45:43.813" Title="What are the details of opening a cockpit door from the outside?" Tags="&lt;safety&gt;&lt;security&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13567" PostTypeId="2" ParentId="13566" CreationDate="2015-03-26T22:50:04.480" Score="29" Body="&lt;h2&gt;I'm going to explain this for the Airbus (also known as the Cockpit Door Locking System or CDLS):&lt;/h2&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;How exactly does the person on the inside &quot;cancel the unlock&#xA;      process&quot; (Press a button, flip a switch, enter &quot;counter code&quot;,&#xA;      etc...)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the code is entered for an emergency external opening, the pilot has 30 seconds after the request period to toggle the door button to lock to deny the request or the door will unlock. It pops back the the 'Norm' position automatically.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;It seems there is a delay before the door opens. Is this&#xA;      correct? What's the duration of the delay?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;30 seconds, unless the lock button is pushed, in which case the request is inhibited for 5 minutes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the &quot;authority levels&quot; of codes? Which levels exist, what do&#xA;  they mean? What is the confidentiality policy regarding those codes in&#xA;  theory and practice? (Who gets what authority level code officially?&#xA;  If&#xA;      stewards/stewardesses are not allowed to have the codes do pilots&#xA;      usually pass them on anyways?)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are indeed two codes, but I believe the normal access one is optional. The (optional) normal code just chimes the cockpit for an opening request, while a secret code to the best of my knowledge is shared among the crew to request emergency access. &lt;em&gt;&quot;There are two different access request types : “Routine” and “Emergency” access request.&quot;&lt;/em&gt; These are however internal airline policies and differ from airline to airline, and I've read in some cases that they might even have the same emergency code across the fleet. In any case, the pilot(s) can still decline access.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://c0.thejournal.ie/media/2015/03/gif-2-germanwings.gif&quot; alt=&quot;gif&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=ixEHV7c3VXs&quot; rel=&quot;nofollow noreferrer&quot;&gt;video about cockpit door&lt;/a&gt; as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://nicmosis.as.arizona.edu:8000/ECLIPSE_WEB/TSE2015/A320_DOCUMENTS/A320_Operating_Manual_PDF_N_FCOM_RJA_TF_N_EU__20130329_DSC_25.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;, Page 37 onwards. While the source suggests that the time can be changed, most sources I've read refer to 5 minutes and 30 seconds as the standard times.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.310" LastActivityDate="2015-03-27T12:34:27.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13568" PostTypeId="1" AcceptedAnswerId="13574" CreationDate="2015-03-26T23:13:39.247" Score="5" ViewCount="3250" Body="&lt;p&gt;Does the FAA Medical Exam for a medical certificate qualify as a Medical Expense per &lt;a href=&quot;http://www.irs.gov/pub/irs-pdf/p502.pdf&quot; rel=&quot;nofollow&quot;&gt;IRS Publication 502&lt;/a&gt; (thus allowing one to deduct the expense, or utilize a Health Savings Account (HSA)/Flexible Spending Account (FSA))?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One possible way to have the medical exam qualify as a medical expense would be to have a standard physical exam and the FAA medical exam together (which might also let you claim it with your &lt;a href=&quot;http://www.crissmanfamilypractice.com/index.cfm/fuseaction/site.content/type/89593/custom/1.cfm&quot; rel=&quot;nofollow&quot;&gt;health insurance&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this interpretation correct or consistent with your experience?&lt;/p&gt;&#xA;" OwnerUserId="3191" LastEditorUserId="62" LastEditDate="2015-03-26T23:41:19.317" LastActivityDate="2015-03-27T03:57:55.370" Title="Is the FAA Medical Exam an IRS Medical Expense?" Tags="&lt;usa&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13569" PostTypeId="2" ParentId="13568" CreationDate="2015-03-26T23:40:46.333" Score="4" Body="&lt;p&gt;It looks like if you're a professional pilot then &lt;a href=&quot;http://www.aviationtaxglossary.com/employee_business_expenses/&quot; rel=&quot;nofollow&quot;&gt;yes&lt;/a&gt; (it's an unavoidable expense for your job). Otherwise, &lt;a href=&quot;http://www.ustaxcourt.gov/InOpHistoric/PetersonMemo.Lauber.TCM.WPD.pdf&quot; rel=&quot;nofollow&quot;&gt;no&lt;/a&gt; (probably, see disclaimer below):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flights in the first three categories [including for FAA medicals] were clearly personal,&#xA;  reflecting petitioner’s family or personal obligations, personal&#xA;  finances, or love of flying&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Aircraft-Ownership/Business-Justification-Flight-Training-Expenses&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; from AOPA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The first thing you'll notice in these regulations is that your flight&#xA;  training expenses will be deductible only if they are trade or&#xA;  business related. Therefore, if your flying is purely personal in&#xA;  nature, you will not be able to take a tax deduction for flight&#xA;  training expenses.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Admittedly that talks about training, not medical expenses, but a medical is required unless you're a sport pilot so it seems to apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I'm not a tax attorney, if you want an answer that will stand up in court than ask someone who is :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-03-26T23:40:46.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13570" PostTypeId="1" AcceptedAnswerId="13571" CreationDate="2015-03-26T23:41:02.853" Score="9" ViewCount="1300" Body="&lt;p&gt;I think, if there is only a 0.1 bar pressure difference with a single square meter door, around the weight of a ton would be needed to open it - if it is sealed hermetically and opens outward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible?&lt;/p&gt;&#xA;" OwnerUserId="7794" LastEditorUserId="7794" LastEditDate="2015-03-27T12:38:57.493" LastActivityDate="2015-03-27T12:38:57.493" Title="If the pilot cabin loses pressure, can the pressure difference lock the cockpit door?" Tags="&lt;cabin-pressure&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13571" PostTypeId="2" ParentId="13570" CreationDate="2015-03-27T00:02:25.867" Score="14" Body="&lt;p&gt;Firstly: Flightdeck doors are to the best of my knowledge not hermetically sealed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly: Doors will normally have one of several solutions employed to safely handle explosive decompression:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some doors have panels that pop out to equalise the pressure, especially inwards.&lt;/li&gt;&#xA;&lt;li&gt;Some doors unlock automatically in one or both directions.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Needless to say, you need one solution in either direction. Whatever pressure difference there is it will most probably very quickly be equalised and there should not be any difficulty in opening the door if need be. &lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-03-27T00:02:25.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13572" PostTypeId="2" ParentId="13550" CreationDate="2015-03-27T00:06:52.303" Score="3" Body="&lt;p&gt;I'm interpreting your question as really two questions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;1. Can commercial aircraft be modified so that they can be remotely piloted?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, with some hardware modifications on the aircraft to allow for command and control and telemetry data to be transmitted.  If installed as a separate system, you would need VHF/UHF antennas, RF amplifiers, FMS/autopilot interface, etc.  On the ground, a bunch of directional antennas and ground stations strategically/geographically placed to allow for maximum coverage.  Realistically, UHF communication is only going to get you out to around 150 miles or so in good conditions.  Any further than that, and you need microwave (GHz frequency) links, and even then, this is no good over the oceans due to curvature of the earth.  HF is an option, but I'm not sure how well you can use that for reliable data transmission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The good news is that ATC towers and aircraft already have equipment that operates at these higher frequencies &amp;ndash; the &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control_radar_beacon_system&quot; rel=&quot;nofollow&quot;&gt;radar transponder/beacon system&lt;/a&gt; &amp;ndash; however, serious modification of the system is required to make this feasible.  Aircraft telemetry requires a much wider bandwidth, and more constant connection than what's necessary to ping back with a simple four-digit code that transponders currently reply with, though it's possible, but probably at the expense of other aircraft flying in the same region, as the directional ground antenna would have to be pointed at the aircraft in question (and not constantly rotating).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;2. Can ground controllers take over in the event of an emergency?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If this became a thing in commercial aviation, it would likely be at the behest of governments and their aviation authorities, not private airlines.  The sheer cost of equipment upgrades would not make, say, Delta and Lufthansa corporate types happy, but it would be very popular with equipment manufacturers like Boeing, Rockwell-Collins, and BAE.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let's say we solved the problem of communication mechanism with the aircraft, we still need command/control equipment on the ground.  The military has long been a pioneer in the field of unmanned systems, and I speak from experience that it has taken a long time to get to the point where they are currently.  Early systems were all a hodgepodge of various protocols, datalink standards, and ground control stations, but ever so steadily reaching &lt;a href=&quot;http://en.wikipedia.org/wiki/STANAG_4586&quot; rel=&quot;nofollow&quot;&gt;commonality&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the earliest attempts at this was the &lt;a href=&quot;http://defense-update.com/20071115_onestation.html&quot; rel=&quot;nofollow&quot;&gt;One Station Ground Control System&lt;/a&gt; (OSGCS), developed in the early 2000's, but even as of five years ago, was not in common use across the board, mostly due to program and fielding costs.  These costs would likely see any commercial-sector implementation at national levels, where command and control centers would house the (most) expensive equipment and the qualified operators, with a network connection to the ATC towers with the communication equipment.  In practical theory, I don't think this would go down well, but let's assume a perfect ATC system for the time being.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So then there's the &lt;strong&gt;security&lt;/strong&gt; of the system.  What prevents anyone from hijacking an aircraft remotely?  Now you need to add a very good authentication/encryption mechanism, and standardize that across national boundaries.  What if it's a foreign carrier over your soil?  And good luck getting the United States to share its cryptography standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's the &lt;strong&gt;human factor&lt;/strong&gt; &amp;ndash; what override procedures are available to the pilots, if any?  What options does the ground commander have at his disposal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I think it's entirely possible, but there are a ton of obstacles to overcome, and implementing this system would take years (probably decades at best) and billions of dollars to achieve.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-27T00:13:38.727" LastActivityDate="2015-03-27T00:13:38.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13574" PostTypeId="2" ParentId="13568" CreationDate="2015-03-27T03:57:55.370" Score="6" Body="&lt;p&gt;If you're asking whether you can pay for one with an HSA or FSA, then yes, &lt;a href=&quot;http://www.irs.gov/publications/p502/ar02.html#en_US_2014_publink1000179002&quot; rel=&quot;noreferrer&quot;&gt;physical exams are eligible expenses&lt;/a&gt;, though consult with your insurance provider first if they are covered by your plan.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Physical Examination&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;You can include in medical expenses the amount you pay for an annual physical examination and diagnostic tests by a physician. You do not have to be ill at the time of the examination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you're looking to add it to a list of itemized deductions, as Pondlife explained, it generally has to be &lt;a href=&quot;http://www.irs.gov/publications/p535/ch01.html#en_US_2014_publink1000208606&quot; rel=&quot;noreferrer&quot;&gt;business- or workplace related&lt;/a&gt;.  If you are a professional pilot, then this is deductible.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;What Can I Deduct?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;To be deductible, a business expense must be both ordinary and necessary. An ordinary expense is &lt;strong&gt;one that is common and accepted in your industry&lt;/strong&gt;. A necessary expense is one that is helpful and appropriate for your trade or business. An expense does not have to be indispensable to be considered necessary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-27T03:57:55.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13575" PostTypeId="2" ParentId="13554" CreationDate="2015-03-27T04:24:13.073" Score="11" Body="&lt;p&gt;I have had a fair bit of experience with CASA, including a close friend who worked for them for a number of years. They have a bad reputation these days but I'm not sure it's entirely deserved. I obviously cannot predict exactly what they would do but I hope to give you some advice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First things first, I would believe your version of events much more than someone on the ground - slant visibility and all that.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulations (CAR 172) effectively states that if you fly into cloud the penalty is 50 penalty points - I think each penalty point is currently 110 dollars so the answer to your question is you could be fined $5500. However, CASA uses discretion as to when to enforce this fine - and the Department of Public Prosecutions gets the final say. If it is not a good use of their time, or if it doesn't really serve the public interest, they won't bother with it. A student pilot who accidentally flew into cloud? I would be very very surprised if they followed it up - particularly because as a student you are under the care of an instructor, who shouldn't let you fly solo if there was cloud in the immediate vicinity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think this would apply to your situation, but a more common course of action for CASA is the &quot;fit and proper person&quot; catch-all. Basically it means CASA must be comfortable that you will be responsible with the powers your licence gives you. CASA uses this power to remove the licences of people who frankly, shouldn't have one. It tends to be reserved for people who break the law either intentionally or through gross negligence. Also for example if you are charged with a non aviation offence, like fraud, CASA might take your licence claiming you are not a fit and proper person to hold one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other items in CASA's arsenal include temporary licence suspension, forced re-training or re-sitting of an exam or flight test. There is also a 'demerit points' system if you are a repeat offender. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some general advice now (remembering that I'm not a lawyer) - don't lie. According to my friend (who should know), CASA is more concerned about your attitude than anything. They want to see people taking responsibility for their mistakes and accepting the consequences. This certainly doesn't assure you immunity but you might find that this reduces a licence suspension from 24 months to 6 months. If you are particularly worried, remember that you don't need to tell CASA anything if you are the person under investigation - like in other legal matters, you have the right to remain silent. Before any action is taken against you you will receive a &quot;show cause&quot; notice, which tells you what they are planning to do and invites you to tell them why they should not do that. If you don't like what they propose I'd advise upon getting a lawyer to respond on your behalf. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But all pilots make mistakes and only 'temporary pilots' pretend otherwise. If you really did fly into that cloud, thoroughly debrief with your instructor and turn it into a learning opportunity. If CASA does come knocking then you can talk about what you have learned and that you are a better pilot for it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, in the circumstances you've described, especially as a student pilot, if CASA comes down on you I would be questioning where my taxes are going. What you are going through must be intimidating but don't be fearful - if your goal is to get into the airlines you will quite likely experience this sort of situation again. As long as your intent was never to break the rules or put anyone in danger, you honestly &lt;em&gt;should&lt;/em&gt; be fine. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-03-27T04:24:13.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13576" PostTypeId="1" AcceptedAnswerId="13580" CreationDate="2015-03-27T05:44:49.843" Score="15" ViewCount="1588" Body="&lt;p&gt;Does the flight data recorder record whether the cockpit door lock was deliberately used to lock someone out?&lt;/p&gt;&#xA;" OwnerUserId="424" LastEditorUserId="595" LastEditDate="2015-03-27T07:56:34.620" LastActivityDate="2019-09-05T21:49:33.153" Title="Does the FDR record data about the cockpit door lock system?" Tags="&lt;flight-data-recorder&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13577" PostTypeId="2" ParentId="13576" CreationDate="2015-03-27T05:56:28.837" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://www.verifavia.com/bases/ressource_pdf/299/icao-annex-6-part-i.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO Annex 6 part 1&lt;/a&gt; (Appendix 8) lists parameters required to be recorded on digital flight data recorders.  This should give you a general sense of what gets recorded, but cockpit door locking state is not among them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The caveat to this is many of these might &lt;a href=&quot;http://www.bea.aero/etudes/use.of.fdr/use.of.fdr.pdf&quot; rel=&quot;nofollow&quot;&gt;not be individually codified in regulation&lt;/a&gt; by member parties to the convention.  Carriers are regulated by their state of registration.  In the United States, cockpit door locking state is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:3.0.1.1.8#se14.3.125_1226&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;not one of the required parameters&lt;/strong&gt;&lt;/a&gt; mandated by the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The original answer specifically mentioned European regulations, but has since changed to a general question.  My answer has been edited accordingly.)&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-03-28T00:25:39.030" LastActivityDate="2015-03-28T00:25:39.030" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13578" PostTypeId="2" ParentId="13519" CreationDate="2015-03-27T07:31:42.453" Score="1" Body="&lt;p&gt;I don't know if there is a global compilation. But for Australian operations data exists to allow us to establish a likelihood of being in an incident. Accidents are so rare that it's difficult to get a reliable indicator, however if we are just measuring reported &lt;em&gt;incidents&lt;/em&gt; I believe we could get somewhere.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Australian Transport Safety Bureau (ATSB) has published an &lt;a href=&quot;http://www.atsb.gov.au/media/5474110/ar2014084_final.pdf&quot; rel=&quot;nofollow&quot;&gt;&quot;Aviation Occurrence Statistics&quot; report&lt;/a&gt; covering 2004-2013.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's focus on high-capacity RPT operations, because lets face it, that is probably what most people are interested in. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the report, in 2013, there were 597,000 departures of Australian-registered high capacity RPT or charter flights (unfortunately the report doesn't seem to split it into RPT only, possibly because we have a lot of high-capacity charter flights to the mines). In the same year there were 3292 reported incidents to the ATSB and 2 accidents. Therefore I would conclude that if in 2013 you boarded an Australian-registered high-capacity RPT or charter flight, your chances of being in a &lt;em&gt;reported&lt;/em&gt; incident were around 0.5%, and chances of being are an accident is 0.06%. The incident percentage is approximately the same for the couple of years prior, so I am confident that this remains around about the mark today - though I would not consider the accident rate to be reliable because there were so few.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incidents cited in this data vary from loss of separation to a pilot being sick to birdstrikes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a read of the report but before you take it as gospel, keep in mind, as they say, &quot;there are lies, damn lies, and statistics!&quot; &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-03-27T07:31:42.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13579" PostTypeId="1" CreationDate="2015-03-27T10:35:57.710" Score="10" ViewCount="32711" Body="&lt;p&gt;Could a non-US citizen come to the US, receive flight training, earn an FAA CPL and be hired by a US-flagged airline? Are there any specific rules regarding the employment of foreigners as pilots for a US-based commercial airline? For the sake of example, an Iranian flying for a US-flagged carrier?&lt;/p&gt;&#xA;" OwnerUserId="7866" LastEditorUserId="62" LastEditDate="2015-03-27T17:13:12.177" LastActivityDate="2019-04-21T09:19:40.170" Title="Can foreign pilots get an FAA ATPL and work for a US-based commercial airline?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;usa&gt;&lt;international&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13580" PostTypeId="2" ParentId="13576" CreationDate="2015-03-27T11:10:37.267" Score="17" Body="&lt;p&gt;While it is not on the required parameters list, it would not surprise me if it would be recorded- most FDRs record considerably more than the 88 mandatory parameters, and cockpit doors are of course interesting in accident investigations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, it &lt;strong&gt;should also come across pretty evidently on the Cockpit Voice Recorder&lt;/strong&gt; if somebody was trying to get in. The normal request is a pretty distinct buzzer and the emergency request is the same buzzer for 5 minutes unless denied/ cancelled by the pilot. The door also locks quite loudly. Both should be able to be picked up by the general cockpit area microphone (CAM).&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="22726" LastEditDate="2019-09-05T21:49:33.153" LastActivityDate="2019-09-05T21:49:33.153" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="13581" PostTypeId="1" AcceptedAnswerId="13583" CreationDate="2015-03-27T12:38:14.910" Score="12" ViewCount="3563" Body="&lt;p&gt;On a plane, as a passanger, I can't hear my own breath. I can't hear my own breath even in a silent room.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a plane, there is a continous background noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the microphone recording the noises in the cockpit, are probably not directly at the lungs of both pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am really wondering, how can the breath of a pilot simply be recorded on the cockpit, if it wasn't designed specifically for that (or it isn't a &lt;em&gt;very&lt;/em&gt; high quality recorder placed directly to the body of the pilots)?&lt;/p&gt;&#xA;" OwnerUserId="7794" LastActivityDate="2015-03-30T19:07:53.963" Title="How can the breath of a pilot be recorded?" Tags="&lt;cockpit-voice-recorder&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13582" PostTypeId="2" ParentId="13581" CreationDate="2015-03-27T12:43:31.363" Score="26" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/5096/609&quot;&gt;One of the channels of the Cockpit Voice Recorder is the microphone on each pilot's headset.&lt;/a&gt; This is much closer to the source of the breathing noise than your own ears. The microphone may also not have a wind filter so breathing on it will generate a lot of noise.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-03-27T12:43:31.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13583" PostTypeId="2" ParentId="13581" CreationDate="2015-03-27T12:45:33.420" Score="13" Body="&lt;p&gt;Pilot's breath is not recorded on a flight data recorder, as it is not one of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:3.0.1.1.8#se14.3.125_1226&quot;&gt;the data parameters&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if a pilot is breathing abnormally, the cockpit voice recorder may easily detect that as the breathing sound is captured by the CVR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A reference to this can be found in the &lt;a href=&quot;http://www.telegraph.co.uk/news/aviation/11498132/Germanwings-Airbus-A320-tragedy-cockpit-recordings-reveal-co-pilot-Andreas-Lubitz-crashed-plane-deliberately.html&quot;&gt;press conference summary&lt;/a&gt; for Germanwings flight 4U9525, which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the only sound to come from Lubitz is the sound of him breathing,&#xA;  &lt;strong&gt;picked up by the microphone on his headphone set&lt;/strong&gt;. ... “We could hear&#xA;  human breathing inside the cabin,” said Mr Robin, “and this breathing&#xA;  noise we heard up until the moment of final impact. That means that&#xA;  the co-pilot was alive. Apparently he was breathing normally, so this&#xA;  is not someone having a heart attack, for example.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="572" LastEditDate="2015-03-27T13:08:58.793" LastActivityDate="2015-03-27T13:08:58.793" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13584" PostTypeId="1" AcceptedAnswerId="13597" CreationDate="2015-03-27T13:12:20.030" Score="11" ViewCount="3542" Body="&lt;p&gt;The trailing edge of and airfoil is mostly pointing downward. Is there any reason for that? Down wash increases drag and down wash is due to the direction of air pointing down. If the trailing edge is made horizontal (or maybe pointing upward), they can produce less down wash and &lt;a href=&quot;http://en.wikipedia.org/wiki/Kutta_condition&quot;&gt;Kutta Condition&lt;/a&gt; can still be satisfied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the specific reasons for this shape?&lt;/p&gt;&#xA;" OwnerUserId="6857" LastEditorUserId="5517" LastEditDate="2015-03-27T16:04:16.583" LastActivityDate="2020-07-20T04:14:23.543" Title="Why do airfoil's trailing edges point downward?" Tags="&lt;aerodynamics&gt;&lt;fixed-wing&gt;&lt;airfoil&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13585" PostTypeId="2" ParentId="13584" CreationDate="2015-03-27T13:17:56.550" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://physics.stackexchange.com/questions/290/what-really-allows-airplanes-to-fly&quot;&gt;This question&lt;/a&gt; discusses different ways to explain why wings generate lift.&#xA;The Newton explanation (wings go up by pushing the wind down) can explain why a wing trailing edge points down. This will increase the angle at which the air is directed downwards, and thus increases lift.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2015-03-27T13:41:45.187" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13589" PostTypeId="2" ParentId="13579" CreationDate="2015-03-27T15:33:20.093" Score="9" Body="&lt;p&gt;At the most basic level, the DHS/Dept.Of State regulations regarding work authorization have to be followed. There are essentially three categories you can be in, as far as employment is concerned:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A naturalized or natural-born U.S. Citizen. You're allowed to work for any U.S. employer.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;An (in-status) permanent resident (green card holder). You're allowed to work for any U.S. employer.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A non-resident. You're allowed to work only with DHS authorization.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The first two are somewhat self-explanatory. Some positions may have special requirements - for example, you can't be a U.S. President without being natural-born. Some employers place limits on non-citizen employment due to various U.S. laws usually related to access to information of military nature or applicable to military needs. Thus, a lot of aerospace manufacturing is off-limits to non-U.S. citizens, simply because the company might also handle aerospace jobs and doesn't wish to sufficiently compartmentalize access. For example, most if not all SpaceX jobs are for U.S. citizens only. No such limitations apply to normal commercial transport pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Permanent Resident Workers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless you're already a permanent resident, you may wonder how to become one. In most cases, someone else - a family member or an employer - must petition on your behalf, you can't apply yourself. There are also strict yearly numerical limits for most &lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/immigrate/employment-based-immigrant-visas.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;permanent resident visa categories&lt;/a&gt;. Citizen or permanent resident family members 21 years of age and older can apply for you, but unless you're petitioned for by a spouse, the waiting times are measured in years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can review the &lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/all-visa-categories.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;directory of Visa categories&lt;/a&gt;, immigrant, with an eye for transport crew employment. I will elaborate only on the categories that apply to a pilot who isn't eligible for another category (say you're not an Iraqi who has worked for U.S. Govt, etc.).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/immigrate/diversity-visa-program-entry.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;DV category - Diversity Visa&lt;/a&gt; - if you seriously think of working in the U.S., you should be applying every year. It's a lottery. Make sure you apply at the official &lt;code&gt;.gov&lt;/code&gt; website; the entry is free.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/immigrate/employment-based-immigrant-visas.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;E Category - Employer-Sponsored&lt;/a&gt;. The first and most obvious requirement is that the potential employer must be willing to spend the money (on the order of $10k) to petition on your behalf. If they can find employees already authorized to work, there's very little incentive to petition.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Assuming that your employer is willing to sponsor an &lt;code&gt;E&lt;/code&gt; immigrant visa on your behalf, the next step is to obtain a labor certification from the Dept. of Labor. A Pilot would most likely fall under the &lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/immigrate/employment-based-immigrant-visas.html#third&quot; rel=&quot;nofollow noreferrer&quot;&gt;third preference&lt;/a&gt;, assuming that a labor certification can be obtained. And here's the real clincher: given the never-ending supply of commercial transport pilots in the U.S., and a lack of any particular special requirement for the job (we aren't talking about test pilots!), there's a nil chance of the DOL certifying the position. The DOL certification process requires the employer to prove that there is an insufficient supply of qualified workers who are already authorized and qualified for the job. So that is, essentially, where it ends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Non-Resident Workers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The third category is the most complex one. There are various kinds of work authorization available, under various programs. All of them have special requirements, thus a non-resident is by default ineligible for any work authorization, unless he/she fulfills the requirements. For example, students on F-1 status are authorized to perform on-campus work, and for certain off-campus jobs iff they amount to practical training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The non-immigrant category (usually Letter-Number, with an optional Letter suffix, e.g. F-1) is indicated on the Visa, but remember that the Visa is merely a document that is necessary (but not sufficient) to enter the U.S. After you're in the U.S., you or your employer can adjust your immigration status, as long as you fulfill the requirements to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, we can review the &lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/all-visa-categories.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;directory of Visa categories&lt;/a&gt;, non-immigrant, with an eye for transport crew employment. I will elaborate only on the categories that apply to a pilot who isn't eligible for another category (say you don't work for NATO or UN, you're not a NAFTA signatory citizen, etc.).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://travel.state.gov/content/travel/en/us-visas/other-visa-categories/crewmember-visa.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;D category&lt;/a&gt; - allows you to work as a pilot, but you must be employed by an international airline, and you can't stay over 29 days. Your employment must be bona-fide; it can't be a sham set up just so that you can mostly work as a domestic pilot.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And that is, unfortunately, &quot;it&quot;. You may be eligible for work if you're a citizen of one of the countries that U.S. has special agreements with, usually based on humanitarian and similar reasons, but those are few.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, FAA regulations don't even enter anywhere in the picture &lt;em&gt;yet&lt;/em&gt;. The DHS regulations are a primary concern here.&lt;/p&gt;&#xA;" OwnerUserId="7871" LastEditorUserId="7871" LastEditDate="2018-01-03T15:03:13.307" LastActivityDate="2018-01-03T15:03:13.307" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13590" PostTypeId="2" ParentId="13581" CreationDate="2015-03-27T15:42:39.767" Score="0" Body="&lt;p&gt;You can actually hear breath on the mic (see ratchet freak's answer above). If you have multiple pilots, you can hear the other guy breathing on the channel intermittently. You do not hear every breath, just the sniffs, intakes, coughs, etc, all the little noises he makes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, when they say &quot;breathing&quot; for that incident, that includes all kinds of little noises that are associated with normal breathing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-03-27T15:42:39.767" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13591" PostTypeId="2" ParentId="13563" CreationDate="2015-03-27T16:12:39.513" Score="4" Body="&lt;p&gt;Such sensors certainly exist. The sensor is as simple as can be: usually a piece of wire. The bonding of the wire to the skin or structural elements dictates what kinds of damage it's sensitive to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;wire&quot; can be in the form of a thin metallization on a thin non-conductive substrate that's intimately glued to the skin - such gives the most sensitivity to cracks, and is a crack detector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you wish to detect whether the rocket is in the process of breaking up, you simply need to run a thin, insulated wire along a longitudinal structural member, such as a tank, and attach it in a few places, but certainly rigidly at the ends. The input is used sometimes for automatic flight termination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major problem with pressure differential sensors is that you really need a big hole to overwhelm the pressurization systems on turbine-powered transports. A pencil-sized or even coin-sized hole is noisy but essentially irrelevant, and no, you won't get sucked out through it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it so? For cabin ventilation to work to begin with, there must be an outflow valve. Such valves, in steady state, have openings way larger than a coin. The more unplanned-for holes you add to the pressurized section, the smaller the outflow valve's opening will be. Only when the outflow valve completely closes and the pressure is still insufficient, you've got a problem...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, the outflow valve's position in steady state can be used as a measure of air leakage elsewhere.&lt;/p&gt;&#xA;" OwnerUserId="7871" LastEditorUserId="7871" LastEditDate="2015-03-27T18:24:26.603" LastActivityDate="2015-03-27T18:24:26.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13592" PostTypeId="2" ParentId="13579" CreationDate="2015-03-27T16:19:10.890" Score="8" Body="&lt;p&gt;Long story short, yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, can non-US citizens get an FAA ATPL? Plenty of non-US citizens - myself included - hold FAA pilot's licenses (although I'm not an ATP). &lt;a href=&quot;https://aviation.stackexchange.com/q/183/62&quot;&gt;This question&lt;/a&gt; has more details, but as long as you're legally in the US with an appropriate visa, and you have TSA approval for training, then you can get any FAA license you want (or can afford!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, are there any rules or limitations on foreigners piloting for US airlines? This is mostly a question about employment law: it's possible to hold a valid FAA license but not be authorized to work in the US. So again, if you have a valid visa or other work authorization then &lt;em&gt;in general&lt;/em&gt; you can be employed by a US airline. Pilots do need background checks but obviously it is possible; Delta's &lt;a href=&quot;http://www.deltajobs.net/pilot_qualifications.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;pilot recruitment page&lt;/a&gt; simply says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Current passport or other travel documents enabling the bearer to&#xA;  freely exit and re-enter the U.S. (multiple reentry status) and be&#xA;  legally eligible to work in the U.S. (possess proper working&#xA;  documents).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There may be some special cases for security-sensitive operations, but aviation in general is fairly international and you can find 'foreigners' flying in national airlines all over the world.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-27T16:25:09.373" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13593" PostTypeId="1" CreationDate="2015-03-27T16:56:00.610" Score="7" ViewCount="1325" Body="&lt;p&gt;What are the mental health standards (if any) that a candidate pilot must meet in order to qualify for a medical certificate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answers for Canada, the US, and Europe would be particularly interesting to me.&lt;/p&gt;&#xA;" OwnerUserId="7874" LastEditorUserId="7874" LastEditDate="2015-03-27T18:26:39.903" LastActivityDate="2015-03-28T11:01:51.287" Title="What mental health standards must a candidate meet in order to qualify for a pilot's medical certificates?" Tags="&lt;usa&gt;&lt;medical&gt;&lt;canada&gt;&lt;eu&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13594" PostTypeId="2" ParentId="13593" CreationDate="2015-03-27T17:06:49.530" Score="4" Body="&lt;p&gt;The US Medical Certificate application form (FAA 8500-8, the thing we fill out online now) includes a question asking if you have or have ever been diagnosed with &lt;code&gt;Mental disorders of any sort; depression, anxiety, etc&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you answer yes &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/app_history/item18/m/&quot; rel=&quot;nofollow&quot;&gt;your application for a medical is subject to additional scrutiny&lt;/a&gt;, and per the FAA's guidance:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An applicant with an established history of a personality disorder that is severe enough to have repeatedly manifested itself by overt acts, a psychosis disorder, or a bipolar disorder must be denied or deferred by the Examiner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For further reading you can find references to the relevant regulations, examination techniques, and guidance on dispositions (Issue, Defer, or Deny the application) &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item47/&quot; rel=&quot;nofollow&quot;&gt;in the FAA's Guide for Aviation Medical Examiners&lt;/a&gt;, and in FARs 61.107, 61.207, and 61.307 (for the first, second, and third class medical standards, respectively).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-27T17:06:49.530" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13595" PostTypeId="2" ParentId="13593" CreationDate="2015-03-27T17:08:06.893" Score="8" Body="&lt;p&gt;&lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/regserv/cars/part4-standards-t42402-1412.htm&quot;&gt;Canada&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.3 The applicant shall have no established medical history or clinical diagnosis which, according to accredited medical conclusion,&#xA;  would render the applicant unable to exercise safely the privileges of&#xA;  the permit, licence or rating applied for or held, as follows: (a)&#xA;  psychosis or established neurosis; (b) alcohol or chemical dependence&#xA;  or abuse; (c) a personality or behaviour disorder that has resulted in&#xA;  the commission of an overt act; (d) other significant mental&#xA;  abnormality&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/&quot;&gt;US&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless otherwise directed by the FAA, the Examiner must deny or defer&#xA;  if the applicant has a history of: [...] (8) Psychosis; (9) Bipolar&#xA;  disorder; (10) Personality disorder that is severe enough to have&#xA;  repeatedly manifested itself by overt acts; (11) Substance dependence;&#xA;  (12) Substance abuse; [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://easa.europa.eu/system/files/dfu/AMC%20and%20GM%20on%20the%20medical%20certification%20of%20pilots%20and%20medical%20fitness%20of%20cabin%20crew.pdf&quot;&gt;EASA (Europe)&lt;/a&gt; (abbreviated):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AMC1 MED.B.055 Psychiatry   (a) Psychotic disorder   (b) Organic&#xA;  mental disorder   (c) Psychotropic substances   (d) Schizophrenia,&#xA;  schizotypal or delusional disorder   (e) Mood disorder   (f) Neurotic,&#xA;  stress-related or somatoform disorder   (g) Personality or behavioural&#xA;  disorder   (h) Disorders due to alcohol or other substance use   (i)&#xA;  Deliberate self-harm   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;AMC1 MED.B.060 Psychology   (a) Where there is&#xA;  suspicion or established evidence that an applicant has a&#xA;  psychological disorder, the applicant should be referred for&#xA;  psychological opinion and advice.   (b) Established evidence should be&#xA;  verifiable information from an identifiable source which evokes doubts&#xA;  concerning the mental fitness or personality of a particular&#xA;  individual. Sources for this information can be accidents or&#xA;  incidents, problems in training or   (c) The psychological evaluation&#xA;  may include a collection of biographical data, the administration of&#xA;  aptitude as well as personality tests and psychological interview.&lt;br&gt;&#xA;  (d) The psychologist should submit a written report to the AME, AeMC&#xA;  or licensing authority as appropriate, detailing his/her opinion and&#xA;  recommendation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-03-27T17:08:06.893" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="13597" PostTypeId="2" ParentId="13584" CreationDate="2015-03-27T20:36:36.130" Score="22" Body="&lt;p&gt;You are right, the trailing edge does not need to point down. Take symmetric airfoils - here the trailing edge runs parallel to the airfoil chord. Or take &lt;a href=&quot;http://m-selig.ae.illinois.edu/flyingWingAfs/&quot; rel=&quot;noreferrer&quot;&gt;reflex airfoils&lt;/a&gt; (like the HQ 34 of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Akaflieg_Braunschweig_SB-13_Arcus&quot; rel=&quot;noreferrer&quot;&gt;SB-13 tailless glider&lt;/a&gt;): Here the trailing edge is indeed pointing upwards, and still this aircraft flies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But to create lift with as little drag as possible, it helps that the trailing edge points slightly down. Why? Because then it will be least in the way of the desired local flow. Lift is created by &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;accelerating air downwards&lt;/a&gt;. The wing deflects the air flowing over it, and the trailing edge should reflect this deflection angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But - as always - too much is not good: The &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=e417-il&quot; rel=&quot;noreferrer&quot;&gt;Eppler 417 airfoil&lt;/a&gt; of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Akaflieg_Braunschweig_SB-7_Nimbus&quot; rel=&quot;noreferrer&quot;&gt;SB-7 glider&lt;/a&gt; was an extreme layout with too much rear &lt;a href=&quot;http://en.wikipedia.org/wiki/Camber_(aerodynamics)&quot; rel=&quot;noreferrer&quot;&gt;camber&lt;/a&gt;. It is said that pilots could still wipe off raindrops near the trailing edge after landing when they had crossed a shower an hour earlier. This means that airflow separated well ahead of the trailing edge on the upper surface, and the raindrops would not be blown away in the separated flow. Flow separation increases drag, and this effect shows that the shape of the Eppler 417 had too much downward camber at the trailing edge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane is large and heavy, its airfoil's rear camber can be higher - an extreme case is shown below. This is an early supercritical airfoil designed by McDonnell-Douglas, and the highly cambered rear part allows it to integrate very effective Fowler &lt;a href=&quot;http://en.wikipedia.org/wiki/Flap_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;flaps&lt;/a&gt;. Flaps help because they allow to change the direction in which the trailing edge is pointing: Low lift coefficients require no flap deflection, or even negative flap angles in gliders, and the higher the lift requirement grows, the more the flaps will be extended, pointing more and more downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Awm0G.png&quot; alt=&quot;Whitcomb 523&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true for control surfaces: Depending on the desired lift change, their trailing edge will point up- or downwards. See below for an example where I plotted the pressure distribution for three flap deflections in one graph. Upper and lower surface pressure are shown by color-coded lines, and lower lines belong to the lower surface. Dashed lines show the inviscid pressure, and solid lines the pressure distribution with friction effects added. The wider two lines of the same color are apart, the more lift is created. Note the contour plot below, which follows the color scheme of the pressure plots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p4Z2X.png&quot; alt=&quot;E502 with three flap angles&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there are slots to re-energize the flow, extreme trailing edge angles are possible and help to create lots of lift at low speed, which helps airliners to get into small airfields. See below the triple-slotted flaps of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_727&quot; rel=&quot;noreferrer&quot;&gt;Boeing 727&lt;/a&gt;, which was designed for regional traffic from and to small airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gJcMu.jpg&quot; alt=&quot;Triple-slotted flaps of the Boeing 272 in landing position&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-10T09:02:29.683" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13598" PostTypeId="2" ParentId="13526" CreationDate="2015-03-27T23:37:20.400" Score="0" Body="&lt;p&gt;The &quot;Two Crewmember Rule&quot; has been mandatory for all US passenger airlines since 9/11 as well as for all foreign airline flights in and out of the US.The only exceptions are a few very small commuter airlines that fly single-pilot in Cessna 402s and Caravans and Piper Chieftains in remote places like Alaska, Hawaii and the V.I. (and Nantucket!).&lt;/p&gt;&#xA;" OwnerUserId="7881" LastActivityDate="2015-03-27T23:37:20.400" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13600" PostTypeId="1" AcceptedAnswerId="13612" CreationDate="2015-03-28T03:03:44.317" Score="9" ViewCount="8007" Body="&lt;p&gt;Most airplanes, when taking off or landing, are in range of small arms fire, i.e. your every day handgun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to take down a commercial airliner by shooting at it with a handgun? Would one shot be enough, or would several be needed?&lt;/p&gt;&#xA;" OwnerUserId="6821" LastEditorUserId="3386" LastEditDate="2015-03-29T06:51:39.770" LastActivityDate="2021-04-10T15:10:46.313" Title="Can a handgun shot take down a commercial airliner?" Tags="&lt;safety&gt;" AnswerCount="8" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13603" PostTypeId="2" ParentId="13600" CreationDate="2015-03-28T04:54:51.807" Score="9" Body="&lt;p&gt;It depends where the shot is fired and what counts as &quot;taking down&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fire a handgun inside the cabin during a regular flight, the pilot will likely divert to the next airport and land. The aircraft is &quot;down&quot;, but probably not in the way you were thinking of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fire at the plane from the outside, in most cases the result will only be detected at the next bigger inspection. If you are &quot;lucky&quot; and hit something important, a system might fail and the airplane is marked for repair after landing. But it will not go down in flames.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the way the question was probably intended to be asked, my answer is No.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-03-28T04:54:51.807" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13604" PostTypeId="1" CreationDate="2015-03-28T05:24:42.720" Score="12" ViewCount="4496" Body="&lt;p&gt;So it seems that we have three basic issues (and possibly more but not as prevalent):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots can crash planes.  Someone can just be suicidal, be part of an extremist/terrorist group, can have a vendetta against someone or just thinks might as well take more down with me.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passengers that get into the cockpits.  I know that the cockpits are locked and pilots are armed but on a lot of flights there is opportunity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Using technology to override aircraft autopilot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So what is the long-term plan to keep these things from happening from a technology point of view?  Is there anything in the makes that will help solve these issues?  I foresee some sort of technology that requires some sort of dual sequenced unlocking to allow a pilot to make a certain % deviation from flight plan.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note:  There have been a lot of answers here that basically say &quot;nothing is being done&quot; and offer up reasons why.  To use the recent incident of a pilot dropping a plane into a mountain as an example, my main question surrounding that is, is there a technology that would see that the pilot was well off course?  Is there technology that would see that the plane had a high risk of crashing?  Is there technology that would prewarn flight control (even if it were a few minutes)?  Is there technology that flight control could override plane and right the ship that is going into the mountain?&lt;/p&gt;&#xA;" OwnerUserId="4040" LastEditorUserId="4040" LastEditDate="2015-03-30T14:42:50.247" LastActivityDate="2015-03-30T14:42:50.247" Title="What technology is being moved forward to keep pilots from crashing planes?" Tags="&lt;safety&gt;" AnswerCount="6" CommentCount="16" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13605" PostTypeId="2" ParentId="13561" CreationDate="2015-03-28T05:37:15.110" Score="1" Body="&lt;p&gt;According to an article on &lt;a href=&quot;http://timesofindia.indiatimes.com/india/Suicides-by-pilots-have-killed-421-flyers-since-1982/articleshow/46720555.cms&quot; rel=&quot;nofollow&quot;&gt; Plane accidents &lt;/a&gt;, since 1982, the pilots committing suicide have killed at least 421 people.&lt;/p&gt;&#xA;" OwnerUserId="7885" LastEditorUserId="3386" LastEditDate="2015-03-28T06:10:44.313" LastActivityDate="2015-03-28T06:10:44.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13607" PostTypeId="2" ParentId="13604" CreationDate="2015-03-28T05:55:53.443" Score="36" Body="&lt;p&gt;Nothing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At present, there are no serious technological plans to prevent pilots from intentionally crashing a plane. There are discussions about making sure that there are always two people in the cockpit, and at some point policies might be changed to make it easier for pilots to enter the cockpit (even if no-one in the cockpit wants them to), but ultimately we trust the pilot to do whatever necessary to ensure the safety of the aircraft (within certain bounds; see the flight envelope protection system in Airbus aircraft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By limiting pilots' ability to control their aircraft, we seriously limit their ability to legitimately deal with emergencies. See, for example, cpast's &lt;a href=&quot;https://aviation.stackexchange.com/questions/13604/what-technology-is-being-moved-forward-to-keep-pilots-from-crashing-planes#comment30243_13604&quot;&gt;example&lt;/a&gt; of one pilot having a medical emergency and the other pilot not being able to divert because they can't get approval. Even if both pilots are conscious and able, such a system would slow them down when responding to emergencies. &lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-03-29T21:19:14.340" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="13608" PostTypeId="2" ParentId="13604" CreationDate="2015-03-28T06:18:59.080" Score="26" Body="&lt;p&gt;You can't. There exists no technical solution to this problem, aside from removing pilots entirely from flight decks. Pilotless aircraft would prevent this, but that's not &quot;stopping the pilot from crashing the plane,&quot; it's removing the pilot entirely (and is then more vulnerable to unforseen situations, unless there's ground control, where you have the same problem where a person can crash the plane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have to pick what will have ultimate control of the aircraft, knowing that if it messes up, you will crash. &lt;em&gt;Something&lt;/em&gt; must have ultimate, non-overridable control. It can be an autopilot or a human or a bunch of humans. Autopilots are much less flexible than humans, making them an imperfect choice for the controller-of-last-resort (even in Airbuses, where the flight envelope protection normally restricts the pilot, it hands control over to them if there's an issue it can't solve, and the pilot can turn it off by pulling enough circuit breakers). If a human has that role, they can crash the plane. If you want two people to have to share that role, you have to deal with what happens when you only have one available and need to act &lt;em&gt;now&lt;/em&gt;. If one person has the role, they can crash the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all problems have technical solutions. Aircraft are designed with the asusmption that a human pilot is in charge, and that they know what they're doing and can deal with abnormal situations. The aircraft can't always tell if there's an abnormal situation; no one on the ground really can either. Trying to have pilots who can't crash the plane is like trying to keep a doctor from murdering a patient (you can't do so through technical means, because no formal rule can perfectly sort out when something is a legitimate response to a problem and when it's not). The only solution is to make sure that pilots aren't the type to intentionally crash planes. Which, I mean, they do a pretty good job of -- intentionally crashing planes is incredibly uncommon among commercial pilots.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-03-28T06:18:59.080" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13609" PostTypeId="1" CreationDate="2015-03-28T07:03:54.663" Score="3" ViewCount="1214" Body="&lt;p&gt;Is there a way to calculate the gliding distance for a remote controlled (RD) jet aircraft, in case of engine failure? We have some telemetry data on the model, giving us speed and altitude so as to plug them on an equation or other model in estimating the glide distance, but we would not want to actually risk destroying the jet by testing a real life scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, for example, our maximum allowed altitude is 500ft Above Ground Level and its speed is about 150 knots; we are interested in calculating the gliding distance if engine power is lost or cut off (the engine is automatically cut off if the jet flies outside radio control range). &lt;/p&gt;&#xA;" OwnerUserId="7886" LastEditorUserId="1961" LastEditDate="2015-03-28T09:46:40.630" LastActivityDate="2015-03-28T11:21:20.697" Title="How can you calculate the gliding distance for a remote controlled jet?" Tags="&lt;aerodynamics&gt;&lt;model-aircraft&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13611" PostTypeId="2" ParentId="13604" CreationDate="2015-03-28T08:10:13.907" Score="12" Body="&lt;p&gt;Systems exist to avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot; rel=&quot;nofollow&quot;&gt;CFIT&lt;/a&gt; (controlled flight into terrain). This has been the leading cause of fatalities in the last 50 years: Intact planes being flown into the ground or mountain sides by disoriented pilots and wrongly entered data. Precise navigation and detailed terrain maps make it possible that the F-16 will not allow its pilot to fly into terrain. Currently, the system on airliners will only warn that ground contact is imminent, but not prevent it. Enabling prevention is long overdue and entirely possible in airliners, and I expect both manufacturers, Airbus and Boeing, to expedite their plans to get such a system certified for adoption into regular airliners. Maybe it will even be made mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will at least allow more time in cases like that of 4U 9525, but it could not entirely prevent them. Just take the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mount_Salak_Sukhoi_Superjet_100_crash&quot; rel=&quot;nofollow&quot;&gt;Mount Salak crash&lt;/a&gt;: The pilots thought they had a database problem and disabled the warnings. The system must enable ground contact when near to airports, and cannot avoid it when the navigation subsystem fails (no GPS contact plus wrong starting coordinates). In the end this kind of thinking reminds me of all those TSA tactics which always focus on preventing the last incident instead of avoiding the next one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, if people are determined enough, they will find a way around all preventive measures. Human ingenuity will always trump bureaucratic procedures.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-29T14:15:27.640" LastActivityDate="2015-03-29T14:15:27.640" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13612" PostTypeId="2" ParentId="13600" CreationDate="2015-03-28T09:22:47.963" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;shooting at it with a handgun&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's really going to depend on the handgun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;James Bond carries a Walther PPK - this is a .32 calibre popgun with rather limited use outside of a small office. Direct hits on &lt;em&gt;people&lt;/em&gt; are usually survivable unless you take a round in the heart or brain. Chances of even hitting an airliner during takeoff or approach are zero - it simply doesn't have the range, and that tiny subsonic projectile will get deflected by the aircraft's wake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Skipping the middle range and going straight for the hand-cannons, we might get somewhere with a Desert Eagle or a Smith &amp;amp; Wesson 500. Remember the posters for the first Terminator movie? The one where The Ah-nuld is wearing sunglasses and holding up some light artillery? These are bigger. At close range, both guns can crack an aluminum engine block&lt;sup&gt;1&lt;/sup&gt; and are one-shot kills on most things smaller than a rhino. Hitting an approaching widebody isn't all that difficult - it's coming toward you, the angle isn't changing, and it's a rather big target. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But aircraft are large, complex systems with a lot of redundancy, so in order to actually take it down we have to hit something critical. Hitting a 767 right in the nose will destroy the weather radar and (maybe, if it has enough energy left) poke a 1/2 inch hole in the forward bulkhead. No one will notice. The flight-deck windows are rather strong, apparently a police sniper tried to take out a hijacker on the flight deck way back in the 1970s and the rifle round (far more powerful) just pock-marked the window. Several hostages were promptly shot as a result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best shot (ha!) is the engines. They don't like ingesting bits of metal but just hitting the fan won't do much. You would have to get very lucky to get the round into the engine itself, where it will promptly do a lot of very expensive damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even if one engine literally goes boom it &lt;em&gt;still&lt;/em&gt; won't crash the plane. Pilots practice for an engine failure on takeoff all the time, and an engine failure on landing is almost a non-event.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydraulic lines for control surfaces are certainly sensitive, but they are well buried in the structure and there are several independent systems. You won't get them all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in conclusion, handguns are sufficiently ineffective at bringing down large aircraft that we really don't need to be concerned about them. There's a reason air forces around the world prefer missiles or 20mm cannon&lt;sup&gt;2&lt;/sup&gt; for this sort of thing. Geese, however, are quite effective if released in sufficient numbers along the takeoff path. Rather noisy though - you won't hide 500 of them anywhere near an airport without someone noticing. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Internet legends of a .50 cal being able to kill a truck refer to the MUCH larger .50 BMG round, available in explosive and armour-piercing and rightfully categorized as a first-class military weapon.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The projectile's the size of your thumb, and the gun fires 6,000 rounds per minute. It'll do your plane like a chainsaw.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-03-28T09:22:47.963" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13613" PostTypeId="1" AcceptedAnswerId="13615" CreationDate="2015-03-28T10:47:01.500" Score="33" ViewCount="11480" Body="&lt;p&gt;I was having a discussion with a friend about the incident in the past days (4U 9525) and more specifically the what could be described as 'Taboo' of Psychological problems among pilots. We came across a few points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They will only reluctantly admit that something is wrong, since risk losing their Medical (hence being 'grounded'). It will only be easier to loose and harder to get back I suspect after this event. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At least for the younger bunch who might have difficulties they will have substantial debt from training that is difficult to pay off. Furthermore, they will have worked hard to get where they are.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Any airline that does suspect something will most probably not allow them near the cockpit again. Should anything happen the airline will be held to blame, since they did allow him to fly despite knowing of the problem.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This brings up the question: &lt;strong&gt;What can a pilot do, career-wise, if they feel they are unable to exercise the profession?&lt;/strong&gt; It seems pretty cornered to me. Perhaps work in dispatch/ network control was the only one I figured their knowledge could come to use. Switching to the simulator I suspect might also be possible, but not for the younger individuals.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="487" LastEditDate="2015-03-29T04:13:31.377" LastActivityDate="2015-09-29T11:59:08.120" Title="What can airline pilots do if they are no longer in the position to fly, career-wise?" Tags="&lt;pilots&gt;&lt;medical&gt;&lt;career&gt;&lt;airline-pilot&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13615" PostTypeId="2" ParentId="13613" CreationDate="2015-03-28T11:08:11.393" Score="40" Body="&lt;p&gt;When I worked in the design department of an aircraft company, I had two types of coworkers: Those with and those without a pilot's license. You could easily spot the difference. In aircraft-related engineering decisions it was soon obvious. I mightily preferred to work with other pilots - they would have a much better grasp of &quot;what looks about right&quot; and not pursue hare-brained, outlandish ideas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See it this way: All managers in car companies have a driver's license, so they have at least some contact with what their companies make. All higher managers where I worked had &lt;strong&gt;no&lt;/strong&gt; pilot's license, and it made work outright awful. They were trained as beancounters, and that restricted their viewpoint. They were simply incapable of telling good engineering from bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have managed to get a CPL, adding an engineering degree on top is not hard. That is my advice to grounded pilots: Go to engineering school and enrich the workforce with your experience.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-28T13:15:50.233" LastActivityDate="2015-03-28T13:15:50.233" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13616" PostTypeId="2" ParentId="13609" CreationDate="2015-03-28T11:21:20.697" Score="2" Body="&lt;p&gt;I think the only way is to test it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Choose a day with very calm wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Set the plane up for fixed speed anywhere between obviously-lower-than-best-glide-speed and obviously-higher-than-best-glide-speed, and make multiple tests with incrementing the speed in small steps (like 5kt). You can probably think out the details of the experiment yourself, but this should work well.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's very difficult to compute these things. Companies like Airbus or Boeing have (probably proprietary) software for this, large clusters, etc., perform test in an aerodynamic tunnel and do many test flights. Since you likely don't have all the equipment, the only thing you can rely on is the test flight.&lt;/p&gt;&#xA;" OwnerUserId="802" LastActivityDate="2015-03-28T11:21:20.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13618" PostTypeId="1" AcceptedAnswerId="13671" CreationDate="2015-03-28T12:09:28.933" Score="4" ViewCount="1017" Body="&lt;p&gt;Is it possible to command an autopilot to start a fixed rate descent? For example to avoid weather during the cruise phase? From what I have read the autopilot would maintain constant speed and altitude until interrupted but havent found a fixed rate descent function.&lt;/p&gt;&#xA;" OwnerUserId="3355" LastEditorUserId="3355" LastEditDate="2015-03-29T10:22:44.703" LastActivityDate="2015-03-30T08:35:16.903" Title="How to command autopilot to start a fixed rate descent?" Tags="&lt;safety&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13619" PostTypeId="1" CreationDate="2015-03-28T15:05:19.493" Score="5" ViewCount="5586" Body="&lt;p&gt;Does a powered aircraft fly faster when in a head wind or with a trailing wind? The question revolves around the head wind should provide 'better' lift, and trailing winds have very little to 'push' against.&lt;/p&gt;&#xA;" OwnerUserId="7890" LastEditorUserId="3170" LastEditDate="2015-03-28T18:45:57.640" LastActivityDate="2015-03-31T02:00:21.613" Title="Is head-on or trailing wind better?" Tags="&lt;aerodynamics&gt;&lt;wind&gt;" AnswerCount="5" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13620" PostTypeId="2" ParentId="13619" CreationDate="2015-03-28T15:13:11.820" Score="15" Body="&lt;p&gt;A tailwind provides a faster groundspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft moves through the air so whether the ground is moving relative to the mass of air has no relevance to the aerodynamics of an aircraft at cruising altitude.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a British Airways passenger jet approached supersonic speed this week as it rode a surging jet stream from New York to London.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;from &lt;a href=&quot;http://www.telegraph.co.uk/news/worldnews/northamerica/usa/11337617/Jet-stream-blasts-BA-plane-across-Atlantic-in-record-time.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Telegraph, 10 Jan 2015&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They mean groundspeed - so the term supersonic is moot.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Boeing 777-200 jet reached a ground speed of 745mph as it rode winds of more than 200mph across the Atlantic. At ground level, the speed of sound is 761mph.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft often use the predominantly westerly† jetstream when flying from the USA to Europe, From Japan to California or across the USA. Flying the other way they pick an altitude to avoid it.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/yByy3.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;Wikipedia&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Jetstream is a high speed, high altitude, wind that blows moderately reliably in one direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lpSkQ.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;&lt;a href=&quot;https://www.metcheck.com/UK/jetstream.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Metcheck&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;† Westerly means &quot;blowing from the west&quot; - towards the east.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-03-28T15:36:17.970" LastActivityDate="2015-03-28T15:36:17.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13621" PostTypeId="2" ParentId="13619" CreationDate="2015-03-28T15:37:09.910" Score="12" Body="&lt;p&gt;Headwind is good for take-off and landing. It adds extra speed for free at the start of the take-off run, rsp. allows to come in slower for landing, reducing the landing distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tailwind is good for enroute flight. It pushes the aircraft forward and adds extra miles per hour for free. The speed relative to the surrounding air is the same at the same power setting and altitude regardless of wind speed, but when measured relative to the ground the wind speed must be added to the air speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on the way back from a tailwind leg the aircraft has to fly in a headwind, and the added time and fuel expense is higher for the sum of both trips in comparison to trips made when no wind is blowing. Why? Let's assume the aircraft will fly at the same power setting, and will achieve 200 mph in still air. The trip to a destination 1000 miles away will take 1000 / 200 = 5 hours in still wind for a roundtrip time of 10 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now add to that a 50 mph tailwind, and the trip will take 1000 / 250 = 4 hours. On the return trip we need to subtract the wind: Now it will  take 1000 / 150 = 6 hours 40 min to fly back. The total flight time with wind is 10 hours 40 min, and those 40 min of longer flight time consume proportionally more fuel and crew time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tailwind is only good when you don't plan to return, or when the wind will have changed when you go back.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-03-28T22:57:45.933" LastActivityDate="2015-03-28T22:57:45.933" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13622" PostTypeId="2" ParentId="13619" CreationDate="2015-03-28T17:48:46.003" Score="5" Body="&lt;p&gt;&lt;strong&gt;Constant wind does not affect the lift or drag of an aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated by others, you will travel faster &lt;strong&gt;in relation to the ground&lt;/strong&gt; with tailwind but your airspeed will stay the same no matter what wind you have. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly after you are in the air, the aircraft travels with the wind, rather then with the surface of the earth. The aircraft wouldn't notice any wind. &lt;strong&gt;For an airborne aircraft, the air always stands still.&lt;/strong&gt; &lt;em&gt;Wind is only the movement of air in relation to the ground,&lt;/em&gt; and the aircraft doesn't relate to the ground once it is airborne. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are having tailwind, the aircraft will travel with the same speed through the air, but with an increased speed over the ground. This is why you take off into the wind: Your airspeed (the speed the aircraft travels through the air, so the sum of windspeed and groundspeed) is higher with a lower ground speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here the maths: Let's say you have 10kt headwind and you are standing at the runway. When standing still your airspeed is already 10kt eventhough your groundspeed is 0kt. As you start moving, the airspeed will always be 10kt more then your groundspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion: The wind doesn't make an airplane faster in relation to the air, but in relation to the ground the wind can change the speed of an aircraft, but not by producing more lift/drag, but by simply moving the aircraft along in the air.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2015-03-28T17:48:46.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13623" PostTypeId="2" ParentId="13326" CreationDate="2015-03-28T18:03:57.417" Score="4" Body="&lt;p&gt;The term &quot;unusable&quot; is a very special definition. It comes from a specific test described in FAA FAR Part 23. It is not the same as the common sense meaning of the word &quot;unusable&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For single engine light planes like Cessna 152, FAA FAR Part 23 requires the available  fuel flow to be 125% of max engine consumption. 150% for pure gravity feed systems.&#xA; At certification test the fuel flow is measured while the level is dropping in the tanks. As soon as the flow rate goes below 125 or 150 % all remaining fuel is declared unusable. This shall be done with the plane supported in  climb nose up atitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the formal term &quot;unusable&quot; means this last amount of fuel might be unavailble in a nose up attitude at full engine power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In level cruise you can normally empty the fuel tanks to the last drop. &lt;/p&gt;&#xA;" OwnerUserId="7892" LastEditorUserId="7892" LastEditDate="2015-07-25T16:32:49.157" LastActivityDate="2015-07-25T16:32:49.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13625" PostTypeId="2" ParentId="13613" CreationDate="2015-03-28T19:19:37.793" Score="6" Body="&lt;p&gt;Commercial glider and balloon flights don't require a medical, nor do certain kinds of instrument instruction. Someone who's is healthy but wouldn't pass a first or second class medical can have a career teaching, or flying commercial flights like sightseeing and advertising. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-09-29T11:59:08.120" LastActivityDate="2015-09-29T11:59:08.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13626" PostTypeId="2" ParentId="13613" CreationDate="2015-03-28T19:49:51.143" Score="10" Body="&lt;p&gt;Pilots are intelligent. They can retrain and become good at some other type of work: aviation mechanic, computer scientist, engineer, law. Some of these fields will pay much better than a pilot career will anyway, so don't worry about the sunk cost of pilot training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are not fit to fly, no amount of bargaining/rationalizing is going to fix that — you've got to move on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The root cause (psychological problems, in your example) is a red herring. You may have to change careers for many reasons: injury, family, health, etc.&lt;/p&gt;&#xA;" OwnerUserId="7874" LastEditorUserId="7874" LastEditDate="2015-03-28T19:55:20.747" LastActivityDate="2015-03-28T19:55:20.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13627" PostTypeId="2" ParentId="13527" CreationDate="2015-03-28T19:55:03.417" Score="2" Body="&lt;p&gt;All certified airplanes are designed to have a (very slight) spiral instability. The opposite case, dutch roll  instability is not acceptable. This will make a plane that is trimmed out straight and level and then left alone without pilot, autopilot wingleveler or other automation to slowly enter a spiral dive with gradually increasing bank angle and sink rate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spiral instability is achieved by having the lateral tail area large enough so when a wing drops slightly by external disturbance and the plane starts to slip in the wing low direction, the tail will turn the plane in the same direction as the wing drop. This is a gentle and harmonic movement, it feels natural to the pilot. If uncorrected it leads to a spiral dive at increased bank angle and speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dutch roll is the result of to small tail area, so when the plane slips for instance to the left, the nose will go right and up. The speed will go down, and if uncorrected will lead to a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is &lt;strong&gt;not&lt;/strong&gt; the case that a plane left unattended (no pilot or autopilot on duty) will largely stay on course and altitude until the fuel runs out. If a plane was stable by itself, flight in low visibilty would not be a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One famous example is the John F. Kennedy Jr. accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/John_F._Kennedy_Jr._plane_crash&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/John_F._Kennedy_Jr._plane_crash&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7892" LastEditorUserId="7892" LastEditDate="2015-03-29T15:08:50.110" LastActivityDate="2015-03-29T15:08:50.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13628" PostTypeId="2" ParentId="13619" CreationDate="2015-03-28T22:50:06.997" Score="2" Body="&lt;p&gt;When looking at the physics, the speed of an aircraft is the &lt;strong&gt;speed relative to the air&lt;/strong&gt;. For this, it is not relevant how the air moves relative to the Earth - or any other planet, for that matter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft does not even &quot;know&quot; the direction of wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there can not be a difference in the aerodynamics, &lt;strong&gt;in a very fundamental way&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ask about the speed relative to the ground, you can just add the vectors of both speeds.&lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="1875" LastEditDate="2015-03-31T02:00:21.613" LastActivityDate="2015-03-31T02:00:21.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13629" PostTypeId="2" ParentId="13619" CreationDate="2015-03-28T23:00:59.657" Score="3" Body="&lt;p&gt;The question actually has nothing to do with aerodynamics. It's a matter of relative motion, which is traditionally considered physics, but IMO is really nothing more than simple vector arithmetic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider this equivalent question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before you board your airplane, you walk through an airport. You approach two parallel &quot;pedestrian conveyor belts,&quot; one moving away from you and one moving toward you. Which one should you walk across if you want to get to the other side faster?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now replace your body with the airplane, and the conveyor belts with &quot;wind&quot; (moving masses of air). Does that make it more clear?&lt;/p&gt;&#xA;" OwnerUserId="7895" LastActivityDate="2015-03-28T23:00:59.657" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13630" PostTypeId="1" CreationDate="2015-03-29T02:21:22.260" Score="17" ViewCount="15154" Body="&lt;p&gt;What hours count towards the total number of flight hours?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a long haul flight, do all the hours of the flight count towards the total? Even if the pilot is resting?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do 10 short flights of 1 hour (that is, 10 times take-off and 10 times landing) count the same as 1 flight of 10 hours (1 take-off, 1 landing)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible that two pilots with 1,000 hour have a totally different real flight experience on their back?&lt;/p&gt;&#xA;" OwnerUserId="914" LastActivityDate="2018-09-20T13:05:16.267" Title="How meaningful is the total number of flight hours?" Tags="&lt;flight-training&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13631" PostTypeId="1" AcceptedAnswerId="34000" CreationDate="2015-03-29T03:05:54.743" Score="24" ViewCount="4032" Body="&lt;p&gt;Specifically if I visit a doctor in Canada who is not a CAME for my regular aviation medical, do I have to tell him/her that I have a pilot's licence?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can imagine why I'm asking.  I just explained to someone that I'm supposed to mention this to any doctor I see.  However, it's been ages since I've flown and I would no longer do this as I haven't even kept my medical up to date.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've just searched the CARS and can't find any reference to this being a law.  Is it possible I was told this by mistake, or as something that's just recommended?  I do recall doing this once or twice and the doctor didn't just pat me on the back and say &quot;good for you&quot;.  He nodded and just acted like it was a normal thing to be told.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure what tags are available, but I'm interested in answers from other countries as well.&lt;/p&gt;&#xA;" OwnerUserId="7897" LastEditorUserId="923" LastEditDate="2015-03-29T05:40:42.900" LastActivityDate="2016-12-17T14:26:18.950" Title="Is there a legal requirement to tell your doctor you are a pilot?" Tags="&lt;medical&gt;&lt;regulations&gt;&lt;transport-canada&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13632" PostTypeId="2" ParentId="13631" CreationDate="2015-03-29T03:20:47.617" Score="24" Body="&lt;p&gt;In the US, you are not required to inform a doctor that you are a pilot. However, on the application for a medical certificate (&lt;a href=&quot;http://flighttraining.aopa.org/pdfs/FAA_Form_8500-8_Medical_App.pdf&quot;&gt;Form 8500-8&lt;/a&gt;) you must list all &quot;visits to health professionals&quot; in the last three years, including type of professional and the reason for the visit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The medical examiner uses that information to guide questions to ask about your medical history: a yearly checkup with your family doctor will not be remarked on, while a visit to a specialist might invite scrutiny about that area of your medical status. Depending on any existing conditions, you may need a letter from your primary doctor explaining your condition, but you would specifically ask for this rather than expect it to be provided.&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-03-29T03:20:47.617" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13633" PostTypeId="2" ParentId="13631" CreationDate="2015-03-29T03:27:50.960" Score="17" Body="&lt;p&gt;You don't have to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is because you &lt;em&gt;do&lt;/em&gt; have to tell your CAME about everything at your next aviation medical exam anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason you are not required to tell your doctor that you are a pilot is because section 602.02 and 602.03 of the CARS give &lt;em&gt;you&lt;/em&gt; the responsibility to not fly if your medical condition or drug you are taking renders you not fit to fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is contact info for Civil Aviation offices and they can help you with that determination: &lt;a href=&quot;http://tc.gc.ca/eng/civilaviation/opssvs/cam-offices-886.htm&quot;&gt;Civil Aviation offices&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CARS are available at one big 4mb web page &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-602.02&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;602.02 No operator of an aircraft shall require any person to act as a flight crew member and no person shall act as a flight crew member, if&#xA;  either the person or the operator has any reason to believe, having&#xA;  regard to the circumstances of the particular flight to be undertaken,&#xA;  that the person (a) is suffering or is likely to suffer from fatigue;&#xA;  or (b) is otherwise unfit to perform properly the person’s duties as a&#xA;  flight crew member.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7874" LastEditorUserId="5562" LastEditDate="2015-03-30T11:47:30.990" LastActivityDate="2015-03-30T11:47:30.990" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13634" PostTypeId="2" ParentId="13630" CreationDate="2015-03-29T03:48:15.417" Score="11" Body="&lt;p&gt;I don't fully understand what you're asking, but here's an attempt to cover the main interpretations (as I see them) from a US perspective:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;When a pilot says &amp;quot;I have 1000 hours&amp;quot;, where does that number come from?&lt;/p&gt;&#xA;&lt;p&gt;Pilots have to log their flight time for various reasons (see &lt;a href=&quot;https://aviation.stackexchange.com/q/12735/62&quot;&gt;this question&lt;/a&gt; and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/tagged/logging&quot;&gt;logging tag&lt;/a&gt;), some legal and some personal. It's a fairly safe bet that anyone with more than - let's say - one hundred hours has flown more than that, at least for some definition of &amp;quot;flown&amp;quot;. One key number is &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilot_in_command&quot; rel=&quot;noreferrer&quot;&gt;PIC time&lt;/a&gt;, i.e. the time that the pilot was legally responsible for the flight, but there are &lt;a href=&quot;https://aviation.stackexchange.com/questions/5075/in-an-airliner-does-the-captain-or-the-first-officer-fly-the-airplane&quot;&gt;different practices&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;noreferrer&quot;&gt;legal requirements&lt;/a&gt; so the numbers will never be consistent between pilots. And a private pilot who 'only' flies his family around in a Cessna 182 will end up with different logged time from a professional pilot who flies an A380 with hundreds of passengers, even if both have spent roughly the same number of hours &amp;quot;at the controls&amp;quot; (which isn't clearly defined anyway).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What time do airline pilots count towards their 'total'?&lt;/p&gt;&#xA;&lt;p&gt;This depends on who's counting. The people who care are the FAA (or other authorities) for legal &lt;a href=&quot;https://aviation.stackexchange.com/search?q=currency&quot;&gt;currency&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/12735/62&quot;&gt;training&lt;/a&gt; purposes; the airline (i.e. employer) for pay, &lt;a href=&quot;https://aviation.stackexchange.com/q/5075/62&quot;&gt;seniority&lt;/a&gt; and scheduling reasons; and the insurance companies for coverage. All these people will have different views of what &amp;quot;time&amp;quot; means, although PIC time is usually the most fundamental measure. But in airline operations especially, SIC is also &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_155&quot; rel=&quot;noreferrer&quot;&gt;well-defined&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/8969/logging-sic-time&quot;&gt;important&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When two pilots say &amp;quot;I have 1000 hours in A320s&amp;quot; (or whatever), do they have the same level of skill and experience?&lt;/p&gt;&#xA;&lt;p&gt;This is impossible to answer. Take two 30 year-old American men (for example) from the same state who have been driving the same make and model of car every day since they were 16 with no accidents or police tickets. Are they equally good drivers or not? Legally speaking yes: they have the same licenses, background and driving record. But most people would agree from personal experience that they know of a &amp;quot;lucky driver&amp;quot; who has avoided police trouble for years despite driving riskily. Fortunately pilots are more strictly regulated than drivers and the flight and medical checks are much more frequent, so the differences are correspondingly smaller.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Of course I'm completely ignoring the operational experiences, e.g. a pilot who flies between JFK and Atlanta every day will accumulate different experience from one who flies between JFK and &lt;a href=&quot;http://en.wikipedia.org/wiki/Podunk&quot; rel=&quot;noreferrer&quot;&gt;Podunk&lt;/a&gt;. And does &lt;a href=&quot;https://aviation.stackexchange.com/q/2685/62&quot;&gt;Sully's experience&lt;/a&gt; make him different from someone else with exactly the same number of PIC hours in the same aircraft models but who &lt;em&gt;didn't&lt;/em&gt; land in the Hudson?&lt;/p&gt;&#xA;&lt;p&gt;I have the feeling that you're trying to ask if someone with more hours is generally a 'safer' or 'better' pilot (I may be completely wrong about this). If so, the short answer is no: it's impossible to compare two people's experiences directly anyway, and it's commonly said in aviation that it's better to fly 1,000 different hours than to fly the same hour 1,000 times. This applies to many other areas of life too :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-29T03:48:15.417" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13635" PostTypeId="2" ParentId="13630" CreationDate="2015-03-29T03:49:32.950" Score="5" Body="&lt;p&gt;For the United States, the relevant regulation is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.51&lt;/a&gt;, which defines requirements for pilot logbook entries. In general, hours will be logged as one of the following categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot-in-Command&lt;/li&gt;&#xA;&lt;li&gt;Second-in-Command&lt;/li&gt;&#xA;&lt;li&gt;Training (i.e. Instruction Received)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Student pilots will log either as Training when flying with an instructor or as pilot-in-command when flying solo. Non-student pilots will log either pilot-in-command (when the Captain or the only pilot) or second-in-command (when acting as First Officer.) For purposes of total hours, all of the above are included.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from the above categories, hours flown solo, in instrument flight conditions, and at night are tracked separately. These factors don't have any bearing on your total hours, but do matter for satisfying pilot certificate eligibility or currency requirements.Flight cycles (number of landings and takeoffs) don't matter in terms of total hours, but number of landings is also logged as a separate parameter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 61.51(e) says the following regarding what can be logged as pilot-in-command time:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time. (1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) When the pilot is the sole occupant in the aircraft;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) When the pilot, except for a holder of a sport or recreational pilot certificate, acts as pilot in command of an aircraft for which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted; or  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) When the pilot performs the duties of pilot in command while under the supervision of a qualified pilot in command &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as whether rest time counts when operating long-haul flights, I wasn't able to find a definitive answer. The regulations in 14 CFR 61.51 don't seem to be terribly clear on that point. Even &lt;a href=&quot;http://www.airlinepilotforums.com/archive/index.php/t-52722.html&quot; rel=&quot;noreferrer&quot;&gt;reading what actual pilots flying such flights have done&lt;/a&gt; seems to show that different pilots have handled it different ways with some logging all of the hours, some logging only when they were 'in the seat,' and others logging a given fraction of the flight time (e.g. logging 2/3 of the time on a 3-man crew where one rotates out to rest.) Perhaps one of our pilots with long-haul experience around here can provide more insight on this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the title question of how 'meaningful' the total hours are, that's a rather subjective question on which different people will have different opinions. Regarding your last question, certainly not every 1,000 hour pilot will have exactly equal experience, but how different their experience may be will vary quite a lot between any given set of two 1,000 hour pilots. It's entirely possible to be a 1,000 hour pilot without ever having sat in a powered airplane (by flying gliders, helicopters, etc.,) for instance.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-03-29T03:49:32.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13636" PostTypeId="2" ParentId="13630" CreationDate="2015-03-29T03:49:44.817" Score="13" Body="&lt;p&gt;As far as what hours are logged, there are a couple of different ways to do the counting.  On a light aircraft, time on the Hobbes meter is generally used, which equates to &quot;engine running&quot; time.  In the military, it's takeoff to landing, usually plus a small amount for taxi time (which may or may not account for all the time that the pilot is actually operating the aircraft).  In the airlines, it's &quot;block to block&quot; time, so pushing back from the gate until stopping at the gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the time all being equal, it isn't.  Not even close.  2000 hours flown from Big Airport A to Big Airport B, 8 hours at a shot, means about 125 takeoffs, approaches, and landings flown, and an equal number monitored.  Almost all of those are radar vectors to an ILS approach -- very standard &amp;amp; predictable.  Five hundred hours as a pilot training instructor probably translates into about 500 landings performed, and many, many more supervised, with a great variety of approaches flown (visual, precision, non-precision, practice emergency patterns, etc)  The &quot;hands on&quot; time on the controls of a military fighter pilot in 500 hours logged is &lt;strong&gt;&lt;em&gt;far&lt;/em&gt;&lt;/strong&gt; greater than the hands on time during 2000 hour trans-Atlantic airline flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is, &quot;hours&quot; is the currency that we have, and so that's how experience is measured.  Not because it's a great measure, but because anything more granular becomes very complicated and subjective.  Does my 1000 hours flying Lear jets count for more than your 1200 hours flying a King Air?  One's a jet, the other a turboprop.  Did one of us fly 3-hour legs mostly on autopilot on clear days, while the other flew 30 minutes at a time, much by hand, with lots of instrument approaches in bad weather?  Who flew with veteran copilots, and who flew with copilots brand new in the airplane?  Who flew to lots of unfamiliar destinations, and who flew the same canned route(s) day after day?  And how does any of that compare with 3000 hours in a C-5?  Or 800 hours in a crop duster?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of this to say, that &quot;hours is hours&quot;, while it overlooks a LOT of very relevant distinctions between some very diverse types of flying, is still the quick and easy comparison between pilots.  Not because it's wonderfully accurate, but because it's possible (we all log hours, after all), and the more detailed comparisons quickly become hard to objectively make.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-03-29T03:49:44.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13637" PostTypeId="1" AcceptedAnswerId="13638" CreationDate="2015-03-29T08:08:09.993" Score="14" ViewCount="5940" Body="&lt;p&gt;I'm a beginner at aviation. I'm currently in training for gliders license.&#xA;Our instructors mentioned that sunglasses are very important if not mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of properties do I need to look for in sunglasses to determine whether they are good for flying? &lt;/p&gt;&#xA;" OwnerUserId="7245" LastEditorUserId="19" LastEditDate="2015-03-29T09:54:39.157" LastActivityDate="2015-03-29T21:23:47.827" Title="What kind of sunglasses are good for flying?" Tags="&lt;pilots&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13638" PostTypeId="2" ParentId="13637" CreationDate="2015-03-29T10:01:32.497" Score="20" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;No polarizing glasses, they make reading anti-glare instruments difficult and sometimes even limit your outside view if the cockpit windows are polarized as well. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Good fit, you don't want to loose them in the slightest of turbulence. Consider fitting a strap so you can temporarily hang them around your neck. They also need to be comfortable if you wear a headset over them. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Neutral colour (grey, grey-green, brown) of the lenses, which does not distort the natural colours too much as that would make distinguishing navigation lights more difficult. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Actually the FAA have published a &lt;a href=&quot;https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/sunglasses.pdf&quot;&gt;safety brochure on sunglasses&lt;/a&gt; which covers many aspects. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-29T15:25:37.713" LastActivityDate="2015-03-29T15:25:37.713" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13639" PostTypeId="1" CreationDate="2015-03-29T12:45:01.123" Score="1" ViewCount="126" Body="&lt;p&gt;With the eyes of a layman, it seems to be a wonderful thing to fly a big airplane between continents. From an initial perspective anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a transatlantic fight, pilots can see the water of the ocean, and the never changing readouts in the cockpit. Years long. Decades long. Only the water, the clouds, the sky, the sun and the sensor readings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until they retire!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, maybe they could get a laptop with them and play on that, but I think it is probably against the rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Isn't it something like a prison for life? How pilots deal with the increasing boredom?&lt;/p&gt;&#xA;" OwnerUserId="7794" LastEditorUserId="396" LastEditDate="2016-07-25T01:46:23.727" LastActivityDate="2016-07-25T01:46:23.727" Title="What do professional commercial pilots do to counteract boredom?" Tags="&lt;pilots&gt;&lt;commercial-operations&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-03-29T13:00:47.847" ContentLicense="CC BY-SA 3.0" />
  <row Id="13642" PostTypeId="2" ParentId="13604" CreationDate="2015-03-29T14:02:02.963" Score="3" Body="&lt;p&gt;First two items in your list are part of class of crash issues so called &quot;controlled flight into terrain&quot; which is part of &quot;human factor&quot; issues. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only way to avoid such crashes is to create airplane without pilots at all, that is what Google try to do with automobiles. And I believe there are no technical problems to do it right now. Modern aircrafts are able to takeoff, flight and land in fully automatic mode right now and do it in much safer manner than most pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However there is social problem, we do not trust computers that much and most people prefere to fly with human pilot in command rather than a autopilot.&lt;/p&gt;&#xA;" OwnerUserId="7906" LastEditorUserId="7906" LastEditDate="2015-03-29T14:11:25.187" LastActivityDate="2015-03-29T14:11:25.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13643" PostTypeId="1" AcceptedAnswerId="13648" CreationDate="2015-03-29T14:38:12.893" Score="3" ViewCount="3082" Body="&lt;p&gt;Could someone accomplish entry with an axe, considering how tough cockpit doors are? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do planes carry axes? &lt;/p&gt;&#xA;" OwnerUserId="7624" LastEditorUserId="3170" LastEditDate="2015-03-29T21:01:13.730" LastActivityDate="2015-03-29T21:01:13.730" Title="Could someone use an axe to break through a locked cockpit door?" Tags="&lt;cockpit&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-03-29T18:51:04.060" ContentLicense="CC BY-SA 3.0" />
  <row Id="13644" PostTypeId="2" ParentId="13637" CreationDate="2015-03-29T15:05:04.283" Score="3" Body="&lt;p&gt;No matter what type you get in the other answers, make sure they're comfortable.  Realize the headset will be pressing the arms into the side of your head.  I used some Oakleys that I think left permanent dents in my skull.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing you may consider as a student is the sunglasses ability to accept a pair of flipdown blinders??(not sure of the name) that are used for IFR training.  Waay better than the hood, but still not as fun as real IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yHIfm.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="7897" LastActivityDate="2015-03-29T15:05:04.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13646" PostTypeId="1" AcceptedAnswerId="13656" CreationDate="2015-03-29T15:40:31.590" Score="20" ViewCount="4975" Body="&lt;p&gt;It's relatively easy to transport jet aircraft like Airbus and Boeing: most of them have a long range, and a few hops at most would get them to the owner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But how would a Cessna manufactured in U.S. be delivered to Dubai? It would not have the range to cross the Atlantic. Taking a brand new single-engine aircraft across a large ocean also sounds very risky (to the occupants). Same story applies to Hawaii.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting there may also require many hops (e.g. Texas -&gt; California -&gt; Canada -&gt; Alaska -&gt; Japan -&gt; Taiwan -&gt; Singapore), making the transportation long and costly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they put on trailers and shipped like cargo? If yes, how is the aircraft taken apart? (I'd imagine even the wing span of a 172 would be too wide for roads in many countries)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: the linked question addresses airliners. I am specifically interested in GA airplanes.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-03-30T06:47:29.300" LastActivityDate="2017-11-12T22:13:42.237" Title="How are GA aircraft ferried from factories?" Tags="&lt;general-aviation&gt;&lt;ferry-flight&gt;&lt;aircraft-purchase&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13648" PostTypeId="2" ParentId="13643" CreationDate="2015-03-29T16:00:39.560" Score="9" Body="&lt;p&gt;Axes are not carried in the cabin and the door is designed to resist attack using tools available in the cabin&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fire/crash axe/crowbar. Fire axes were provided to obtain emergency access to areas and parts of the airplane which are not easily accessible (e.g. behind sidewall, electrical or ceiling panels). The handle is insulated to protect against electric shock. In the past, fire axes might be found in the flight deck and in the passenger cabin but on most carriers, in compliance with anti-terrorism regulations and procedures, axes are no longer carried and have been replaced by insulated crowbars in the passenger/cargo compartment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.skybrary.aero/index.php/Cabin_Fire&quot;&gt;http://www.skybrary.aero/index.php/Cabin_Fire&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-03-29T16:00:39.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13650" PostTypeId="2" ParentId="13604" CreationDate="2015-03-29T17:54:07.480" Score="2" Body="&lt;p&gt;Other than background checks and rules of practice about who is allowed to fly what when and who can/must be in the cockpit, &lt;strong&gt;no technical measures&lt;/strong&gt; are currently being moved forward for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think I'd want to have such technical measures in place, either.  Sometimes, a pilot &lt;em&gt;needs&lt;/em&gt; to crash-land an airplane in the best interests of public safety.  The &quot;Miracle on the Hudson&quot; is probably the best example of this - the pilot could have tried to get to a landing strip but would likely have tragically crashed in a populated area; instead the pilot &lt;em&gt;chose&lt;/em&gt; to crash-land the plane by flying it into terrain in a particular way that fortunately led to no loss of life by anybody on the plane or ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight 93 (to the extent that the general population now accurately understands the story of what happened on the 4th 9/11 jet) is another good example of when flying the plane directly into the ground, even if that kills everybody on board, was better than an alternative which would have probably killed everybody on board and a whole lot more.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially if there is a loss of cabin pressure or other emergency where a pilot needs to descend rapidly and change the route, having the authority to do that is important.  &lt;/p&gt;&#xA;" OwnerUserId="7911" LastActivityDate="2015-03-29T17:54:07.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13651" PostTypeId="2" ParentId="13646" CreationDate="2015-03-29T17:57:45.660" Score="7" Body="&lt;p&gt;You can often get to Reykavic airport in Iceland for crossing the Atlantic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that hop is still too far you can install extra fuel tanks in the cargo hold and/or passenger area temporarily.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-03-29T17:57:45.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13654" PostTypeId="2" ParentId="13646" CreationDate="2015-03-29T19:07:33.417" Score="3" Body="&lt;p&gt;I can't tell you, if this applies to Cessnas or not, but at least some of the lighter planes are simply shipped by ship or cargo planes. They take those apart. Not completely of course, but they take off the wings and tail. Once they are arrived, they put them back together or leave that part to the new owner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know whether this applies to all or some planes, but at least my boss's was transported this way. He went to Rotterdam to pick it up.&lt;/p&gt;&#xA;" OwnerUserId="3916" LastEditorUserId="65" LastEditDate="2015-04-06T14:21:28.123" LastActivityDate="2015-04-06T14:21:28.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13655" PostTypeId="2" ParentId="13631" CreationDate="2015-03-29T19:46:17.147" Score="5" Body="&lt;p&gt;In Norway all Your medical records are stored in one database.&#xA;Every doctor, public or private, have access to this register, they will also add Your visit in the database.&#xA;Only way to get around this database is to visit a witch doctor or see a doctor outside the country.&lt;/p&gt;&#xA;" OwnerUserId="7914" LastActivityDate="2015-03-29T19:46:17.147" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13656" PostTypeId="2" ParentId="13646" CreationDate="2015-03-29T19:51:08.547" Score="22" Body="&lt;p&gt;As you've guessed, there are two options: a ferry flight, or shipping the aircraft in a container.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ferry flights are quite common; the recent &lt;a href=&quot;https://aviation.stackexchange.com/q/12048/62&quot;&gt;Cirrus ditching&lt;/a&gt; in the Pacific was a ferry flight to Hawaii. As well as planning a suitable route and dealing with permits and paperwork, refueling etc., the ferry company may install &lt;a href=&quot;https://en.wikipedia.org/wiki/Ferry_tank&quot; rel=&quot;nofollow noreferrer&quot;&gt;extra fuel tanks&lt;/a&gt; to give more range, and provide the pilot with specialized survival and communications gear. And an airline ticket home, of course :-) This might all seem expensive, but considering that a new top-of-the-range Cirrus SR22 has a &lt;a href=&quot;http://cirrusaircraft.com/howtobuy/&quot; rel=&quot;nofollow noreferrer&quot;&gt;list price&lt;/a&gt; of almost USD 800,000 you can imagine that ferry costs aren't necessarily a big deal in comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second option is to put the aircraft in a container and ship it, and there are &lt;a href=&quot;http://www.woodstockair.com/export.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;some companies&lt;/a&gt; who specialize in this (the page has some small photos of aircraft in containers). The major concern in this case is removing the wings: gliders and many experimental (e.g. home-built) aircraft are designed to have their wings removed for storage and transportation (towing behind your car) but most typical Cessnas, Beechcraft etc. aren't. You need to have the aircraft professionally and carefully prepared and then re-assembled and checked after delivery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which option is best depends on the costs of each option and the value of the aircraft. There's also the consideration that if you buy a 60-year old aircraft from the other side of the world, ferry companies may decline to fly it to you because of the risks of subjecting it to the stresses and weather of a very long series of flights. Or their/your insurance company may refuse cover for a ferry flight for the same reason. Or perhaps the aircraft is certified for VFR only, which would make a long ferry journey much more difficult to plan and execute. In those cases, container shipping may be the only available option.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-09-12T12:34:47.293" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13657" PostTypeId="1" CreationDate="2015-03-29T20:16:59.797" Score="20" ViewCount="3390" Body="&lt;p&gt;Only some countries use Daylight Saving Time. In Canada, some provinces use and don't use DST (such as Saskatchewan). However, in remote and local regions where this is not observed, what would happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens when areas that do not observe DST are controlled by areas that do. (Cleveland controls parts of Southern Ontario). How does this affect local airspace? Does it affect global airspace as well? What are the safety implications? How does it affect Air Traffic Controllers operating these different spaces?&lt;/p&gt;&#xA;" OwnerUserId="7670" LastEditorUserId="19766" LastEditDate="2018-11-24T16:31:41.503" LastActivityDate="2018-11-24T16:31:41.503" Title="Does Daylight Saving Time affect local airspace?" Tags="&lt;regulations&gt;&lt;time&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="13658" PostTypeId="2" ParentId="13657" CreationDate="2015-03-29T20:21:00.070" Score="10" Body="&lt;p&gt;Air Traffic Control uses &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot;&gt;UTC or Zulu time&lt;/a&gt; which is the same, all the time, the whole world over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Local only flights will use local time.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="19" LastEditDate="2015-03-29T20:22:36.497" LastActivityDate="2015-03-29T20:22:36.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13659" PostTypeId="2" ParentId="13657" CreationDate="2015-03-29T20:23:46.940" Score="3" Body="&lt;p&gt;In all air traffic control systems, all time is UTC (called &quot;Zulu time&quot;), which doesn't have daylight savings. Local time is only used when communicating with passengers (departure/arrival boards, announcements, boarding tickets, etc).&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="6919" LastEditDate="2015-03-30T02:55:11.397" LastActivityDate="2015-03-30T02:55:11.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13661" PostTypeId="2" ParentId="13657" CreationDate="2015-03-29T20:30:45.213" Score="28" Body="&lt;p&gt;Aviation always uses &lt;a href=&quot;http://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot; rel=&quot;nofollow noreferrer&quot;&gt;UTC time&lt;/a&gt;. This is &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0402.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;from&lt;/a&gt; the FAA's AIM, but other countries do the same for obvious reasons:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;4-2-12. Time&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. FAA uses Coordinated Universal Time (UTC) for all operations. The&#xA;  word &quot;local&quot; or the time zone equivalent must be used to denote local&#xA;  when local time is given during radio and telephone communications.&#xA;  The term &quot;Zulu&quot; may be used to denote UTC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/11340/62&quot;&gt;This question&lt;/a&gt; covers in much more detail why UTC is used in preference to &lt;a href=&quot;http://en.wikipedia.org/wiki/Greenwich_Mean_Time&quot; rel=&quot;nofollow noreferrer&quot;&gt;GMT&lt;/a&gt;, and &lt;a href=&quot;https://aviation.stackexchange.com/q/9695/62&quot;&gt;this question&lt;/a&gt; explains why pilots need to know the time in the first place, at least under &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;IFR&lt;/a&gt; (which applies to almost all airline flights).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-03-29T20:30:45.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13662" PostTypeId="2" ParentId="13637" CreationDate="2015-03-29T21:23:47.827" Score="1" Body="&lt;p&gt;There are some good answers to a similar question &lt;a href=&quot;https://aviation.stackexchange.com/questions/12199/is-flying-without-sunglasses-in-daylight-doable-in-a-cessna-172/12396#12396&quot;&gt;here&lt;/a&gt; which may help you on some general things. But as mentioned no polarization due to its issues with glass cockpits. Good eye coverage is key and this will depends on your eyes and how different glasses sit on your face. There are lots of low profile sunglasses out there that may look cool but let a lot of light in on top and bottom of the lenses. Also as mentioned they need to fit under your headset nicely so some larger frame stuff wont work that well. I prefer the Ray-Ban aviators (non polarized) with the classic green lens. They sit will under head sets and have nice coverage. Avoid any lens that has a gradient tint, I tried to fly with a pair of gradient tinted aviators I also own and it was miserable.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-29T21:23:47.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13663" PostTypeId="1" CreationDate="2015-03-30T00:39:42.673" Score="6" ViewCount="867" Body="&lt;p&gt;What is the longest flight time for a single pilot alone in an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="7874" LastActivityDate="2017-12-26T03:31:12.600" Title="What is the record length of time for single-occupant flight?" Tags="&lt;aviation-history&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13665" PostTypeId="1" CreationDate="2015-03-30T02:16:03.213" Score="7" ViewCount="482" Body="&lt;p&gt;How sensitive is the cockpit voice recorder?  Can it pick up sounds from the passenger cabin?&lt;/p&gt;&#xA;" OwnerUserId="7918" LastEditorUserId="6919" LastEditDate="2015-03-30T03:45:19.023" LastActivityDate="2015-03-30T05:19:10.907" Title="Can noise from the passenger cabin be picked up by the cockpit voice recorder?" Tags="&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13667" PostTypeId="2" ParentId="13618" CreationDate="2015-03-30T03:27:17.463" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/110/7874&quot;&gt;This answer&lt;/a&gt; explains that there is a flight level change mode and a vertical speed mode. The latter will hold vertical speed until a target altitude is reached.&lt;/p&gt;&#xA;" OwnerUserId="7874" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-30T03:27:17.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13668" PostTypeId="2" ParentId="13665" CreationDate="2015-03-30T04:32:04.577" Score="-4" Body="&lt;p&gt;I only have experience with general aviation (GA) aircraft, that being said, I bet the intercom in a commercial airliner is similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is something in GA called &quot;squelch&quot; which is like a minimum volume limit for the microphone to turn on.  This makes it so background noise (such as the engine) doesn't make it into the intercom system.  If commercial airlines use this same technology it is very likely that any background noise from passengers is not going to get picked up by the intercom system, and it will not be recorded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, a commercial airline is much quieter than most GA aircraft, so they might not use squelch.  However, the microphones are still going to be pressed up against the pilot's lip, and any sound from the cabin that makes its way through the air, and cockpit door is going to be so quiet that it will be indistinguishable by the time it gets to the pilot's microphone. &lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2015-03-30T04:32:04.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13669" PostTypeId="2" ParentId="13665" CreationDate="2015-03-30T05:11:41.990" Score="9" Body="&lt;p&gt;It depends a bit. One of the microphones for the cockpit voice recorder is an &quot;area microphone,&quot; which is designed to record whatever someone standing in the cockpit would hear (the others record from crew headsets and possibly the PA system). This area mic is continuously recording; it does not just turn on when there's more than some threshold of noise. If the noise in the cabin is loud enough to have been heard in the cockpit, it will be heard on that mic. If not, it won't.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="923" LastEditDate="2015-03-30T05:19:10.907" LastActivityDate="2015-03-30T05:19:10.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13671" PostTypeId="2" ParentId="13618" CreationDate="2015-03-30T08:35:16.903" Score="7" Body="&lt;p&gt;Here is what typical autopilot controls look like&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6j0Ix.gif&quot; alt=&quot;&quot;&gt;&lt;sub&gt;&lt;sub&gt;&#xA;Image source: &lt;a href=&quot;https://aviation.stackexchange.com/questions/2702/what-is-a-flight-director&quot;&gt;What is a &amp;quot;Flight Director&amp;quot;?&lt;/a&gt;&lt;/sub&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot can set the required altitude, as well as the required vertical speed to get to that altitude. A cruise decent will typically use a shallower descent than an approach descent.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-03-30T08:35:16.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13672" PostTypeId="2" ParentId="13663" CreationDate="2015-03-30T09:44:33.497" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What is the longest flight time for a single pilot alone in an aircraft?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;13 days if a balloon counts as an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Balloon&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Steve_Fossett#Balloon_pilot&quot; rel=&quot;nofollow noreferrer&quot;&gt;Steve Fossett&lt;/a&gt; set a record in 2002&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 2002, he became the first person to fly around the world &lt;strong&gt;alone, nonstop&lt;/strong&gt; in any kind of aircraft. He launched the 10-story high balloon Spirit of Freedom from Northam, Western Australia on June 19, 2002 and returned to Australia on July 3, 2002, subsequently landing in Queensland. Duration and distance of this solo balloon flight was 13 days, 8 hours, 33 minutes (14 days 19 hours 50 minutes to landing), 20,626.48 statute miles (33,195.10 km).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Other types of aircraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The following information was volunteered in comments by &lt;a href=&quot;https://aviation.stackexchange.com/users/7874/scary-spice&quot;&gt;Scary Spice&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%c3%a4mpf&quot;&gt;Peter Kämpf&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Glider&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_endurance_record&quot; rel=&quot;nofollow noreferrer&quot;&gt;Charles Atger&lt;/a&gt;, stayed aloft for 56.25 hours, solo. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Powered airplane&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.charleslindbergh.com/history/paris.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Charles Lindbergh&lt;/a&gt; was all by himself for 33.5 hours.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Spacecraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Ron Evans, Apollo 17 Command Module Pilot, was alone for 79 hours, 49 minutes.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="24690" LastEditDate="2017-12-26T03:31:12.600" LastActivityDate="2017-12-26T03:31:12.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13673" PostTypeId="1" AcceptedAnswerId="13682" CreationDate="2015-03-30T09:49:08.697" Score="12" ViewCount="1207" Body="&lt;p&gt;Focusing on aircraft, not balloons, I found &lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology&quot;&gt;this question&lt;/a&gt; that led me to some basic research on &lt;a href=&quot;https://en.wikipedia.org/wiki/Atmospheric_satellite&quot; rel=&quot;nofollow noreferrer&quot;&gt;atmospheric satellites&lt;/a&gt;. I imagine the technology has evolved since &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_Pathfinder&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA's research&lt;/a&gt; more than 10 years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the following points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft cannot stay in flight forever, as it must land for maintenance (as would any aircraft).&lt;/li&gt;&#xA;&lt;li&gt;In 2001, NASA planned a &lt;a href=&quot;http://www.nasa.gov/centers/dryden/history/pastprojects/Helios/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;40h long trip&lt;/a&gt; based on solar powered technology.&lt;/li&gt;&#xA;&lt;li&gt;A fuel-powered UAV can stay up to &lt;a href=&quot;http://www.spacewar.com/reports/Northrop_Grumman_Global_Hawk_Unmanned_Aircraft_Sets_33_Hour_Flight_Endurance_Record_999.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;33h in flight&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Qinetiq_Zephyr&quot; rel=&quot;nofollow noreferrer&quot;&gt;Qinetiq Zephyr&lt;/a&gt; stayed aloft about 2 weeks.&lt;/li&gt;&#xA;&lt;li&gt;Redundancy can be added to continue operation in case of equipment failure (as in any commercial aircraft).&lt;/li&gt;&#xA;&lt;li&gt;'Real' satellite can stay airborne for several years (payloads seem to be able to operate several years without maintenance)&lt;/li&gt;&#xA;&lt;li&gt;If the aircraft can land, the payload and equipment do not have to be as reliable as they would on 'real' satellites, as they could be changed or repaired.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For an atmospheric satellite based on solar-powered airplane technology such as the NASA's Helios, operated in normal conditions, what is the most restrictive element that make landing compulsory?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-10-03T18:22:03.150" Title="What would prevent a solar powered aircraft staying aloft forever?" Tags="&lt;aircraft-design&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13674" PostTypeId="2" ParentId="4962" CreationDate="2015-03-30T10:15:15.330" Score="9" Body="&lt;p&gt;Unfortunately I have no experience with how FSX models aircraft, but at a guess, it's model requires extensive experimental data from a real aircraft to truly get the right parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that's something no hobbyist is likely to be able to do. For that matter, it's pretty difficult for a pilot to do, since actually recording the relevant data is difficult, and some of what you need to know requires doing things with the aircraft you probably shouldn't do in most circumstances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-Plane's flight model and aircraft creation tool is far more forgiving. You still end up having to guess a lot of parameters, but they are generally less critical to basic handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All you really need to get a decent flight model out of X-Plane is a good set of reverence pictures, an eye for detail (so your model matches the geometry properly), and ideally the correct airfoil profiles and engine specifications.&#xA;(Primarily the thrust and power)&#xA;For the most part, good reference models and diagrams, and the information you'd find in the Pilot's operating handbook is enough to create a decent flight model in X-Plane.&#xA;It certainly won't be perfect, and you'll probably have to tune it, but it's a much easier task than getting that data needed for an FSX model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have the good fortune of being a student pilot, and as such I decided to attempt a model in X-Plane, and found that while it was far from perfect, (and needs a lot of improvement to be a 'good') model, it's behaviour was much closer to the real aircraft that I fly regularly than I was ever expecting given how much I had to guess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had to guess everything from the aileron deflection angles to the propeller geometry, wing airfoil choices and more, and still the resulting model was only slightly off from the real thing insofar as I know how the real aircraft flies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess that's not an overly helpful answer in a direct sense for an FSX flight model, but I fear it just isn't going to be at all easy to find the information you need to make a flight model that isn't fundamentally broken in FSX, let alone accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-Plane is just far simpler to work with when you don't have a lot of information...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether that's worth the downsides of X-Plane (especially the consequences of switching if you already have a heavy investment in FSX), I don't know.&#xA;But it's worth keeping in mind if you are particularly fond of amateur aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(It's even plausible to create fictional designs in x-plane for which no real-world data could ever exist in theory, and still get a good idea of how such a design likely would fly if it did exist.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for FSX potentially having better flight models in some cases? Maybe. But this is likely going to be the flight models of expensive add-on aircraft models that were made with the help of the manufacturer and pilots qualified to fly the real aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's not going to help you any if you don't have access to those kinds of resources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A hand-tuned model matched to exact real-world data may well work better than a physics based model if you have good source data.&#xA;But if your source data is lousy (as it is for most of us unfortunately), then the physics based model will be much more reliable most of the time...&lt;/p&gt;&#xA;" OwnerUserId="7927" LastEditorUserId="97" LastEditDate="2015-03-30T17:59:30.213" LastActivityDate="2015-03-30T17:59:30.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13676" PostTypeId="2" ParentId="13604" CreationDate="2015-03-30T12:30:02.147" Score="1" Body="&lt;p&gt;Requiring two pilots in the cockpit at all times. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure that counts as a technological solution however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could imagine they could put emergency intercoms to air traffic control outside the cockpit and allow air traffic control to take control of an aircraft in an emergency.  Or at least to remotely open the cockpit door. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or... you could let the passengers vote electronically for whether the cockpit door should be opened or not...&lt;/p&gt;&#xA;" OwnerUserId="7930" LastEditorUserId="7930" LastEditDate="2015-03-30T13:46:20.620" LastActivityDate="2015-03-30T13:46:20.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13677" PostTypeId="1" AcceptedAnswerId="13683" CreationDate="2015-03-30T13:27:17.143" Score="9" ViewCount="4193" Body="&lt;p&gt;I've heard that in case a commercial flight does not respond to Air Traffic Control, military jets would &lt;strong&gt;&lt;em&gt;always&lt;/em&gt;&lt;/strong&gt; be scrambled to check the state of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefits of scrambling jets are clear. My question is, are they always scrambled in every case?&lt;/p&gt;&#xA;" OwnerUserId="3915" LastEditorUserId="3386" LastEditDate="2015-03-31T13:10:08.580" LastActivityDate="2015-03-31T15:52:34.873" Title="Are military jets always scrambled when communication to a commercial aircraft is lost?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;military&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13679" PostTypeId="1" AcceptedAnswerId="13681" CreationDate="2015-03-30T13:41:35.957" Score="0" ViewCount="2991" Body="&lt;p&gt;In general what can i expect of small, 4-seat, light airplane? I am specifically interested in the &lt;a href=&quot;http://www.pipistrel.si/plane/panthera/overview&quot; rel=&quot;nofollow&quot;&gt;Pipistrel Panthera&lt;/a&gt;, though general responses would be appreciated.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is usual range of that kind of plane?&lt;/li&gt;&#xA;&lt;li&gt;What is the worst weather under which it can fly?&lt;/li&gt;&#xA;&lt;li&gt;How expensive is to fly internationally with that kind of plane?&lt;/li&gt;&#xA;&lt;li&gt;What is the procedure and usual cost for example if I fly from Rome to Prague, what border control checks can I expect? How and what kind of taxes related to that particular flight would I pay?&lt;/li&gt;&#xA;&lt;li&gt;If a plane is declared to have range of 1900 km, what is practical range in practice?&lt;/li&gt;&#xA;&lt;li&gt;If regular service for an airplane is declared to be after 7000 km of flight or X hours of flight, what has to be done usually in those services? Changing of oil, changing of filters?? How expensive usually is that?&lt;/li&gt;&#xA;&lt;li&gt;Anything else you think is important to know about possessing and airplane of that type?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7932" LastEditorUserId="5517" LastEditDate="2015-03-30T13:49:24.267" LastActivityDate="2017-05-23T03:55:44.610" Title="What are capabilities of small Airplane in general?" Tags="&lt;ppl&gt;&lt;economics&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2015-03-30T14:50:05.843" ContentLicense="CC BY-SA 3.0" />
  <row Id="13681" PostTypeId="2" ParentId="13679" CreationDate="2015-03-30T14:00:14.417" Score="2" Body="&lt;p&gt;You have a few questions and the answers to them vary greatly based on the plane in question. It's often said you should chose the plane for your &quot;mission&quot; which means you should think about what you would like to do with the plane and then chose the plane that best fits that &quot;mission&quot;. But anyway let's address some of the questions at hand. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is usual range of that kind of planes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on the plane. Small planes can get anywhere from 500 nautical miles to upwards of 1500 nautical miles depending on fuel load and optional tank configuration. But the middle of that range seems to be the average. I have found that range is more dependent on how long &lt;strong&gt;you&lt;/strong&gt; can sit in the plane not now much gas you can carry. Remember there is no bathroom on these little planes and some are not the most comfortable things in the world. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the worst weather under which it's ok to fly that kind of&#xA;  airplane?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although this is changing most small aircraft are not certified to fly in ice. Some can be modified to do so and some come with the option when you buy it. That being said I don't know if I would fly a small plane in ice but IMC is possible and done all the time. Remember also that fancy equipment does not always mean you are safer, you are still flying a tiny plane in bad weather. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rain is possible but keep in mind rain on the ground could mean ice in the air depending on the temperature. Some small airplanes will be able to climb above this but that depends on plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind is limited by the airports you are flying to and from. If the wind is blowing down the runway you are good to go but every small plane has a maximum demonstrated crosswind component that will limit your ability to fly in high winds at some single runway airports where a crosswind landing is the only option. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How expensive is to fly internationally with that kind of plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again this changes from plane to plane and country to country. Small pipers can be flown for (from what I have read) under 10K(USD) a year and less if you don't fly very often. With older planes you will pay more in maintenance and less in up front cost while with a new plane you will pay more to buy it and less to maintain it as its fresh. You will also have to factor in gas and insurance. Insurance depends on YOU and your flying time so its hard to say what that will fall in. Gas here in the US (100LL) is around 4.56-6.00 where I am so figure in that based on fuel burn etc. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the procedure and usual cost for example if I fly from Rome to Prague, how the border control checks me, how and what kind of taxes related to that particular flight do I pay. Please, don't miss anything.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't fly in the EU so I will refrain from commenting here.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a plane is declared to have range of 1900 km, what is practical&#xA;  range in practice?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here in the US you are required to flight plan with enough fuel for your flight plus 30 minutes of reserve. I don't like when companies put range because this is very much based on the winds and your course. If you get a 40 knot tail wind you will very quickly increase your range, while a 40 knot headwind will bring the number back equally as much. I would calculate range based on usable fuel and fuel burn of the engine. but if they are saying 1900KM I would plan for the 1750KM range to be safe. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If regular service for an airplane is declared to be after 7000 km of flight or X hours of flight, what has to be done usually in those services? Changing of oil, changing of filters?? How expensive usually is that?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft service is (as far as I know) done on hours not miles flown (although they are related in a way. Here in the US you need a yearly inspection which includes lots of things like testing gear and other components and ever XXXX hours when your engine hits TBO (to be overhauled) you need to overhaul it. This overhall can be costly but is very dependent on the engine. It can range anywhere from 15K to (insert large number here). You are also responsible to have anything fixed should it break obviously. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cost to park &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are 2 things here your storage cost and the cost when you actually go somewhere. I fly out of KPNE and have spoken to a few people about the cost of a tie down/hangar. It seems I can keep an airplane in a tie down for less than $100 a month but it would be outside all the time. Hangars get pricy and can be rented or bought. There are lots of small airfields where I am and I'm sure its possible to store a plane for cheaper than at KPNE. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for going somewhere that depends on ramp fees. Here in the US these fees are sometimes waived if you buy gas or very nominal in the first place. Some airports also have a small landing fee (KPNE is $5). I don't know about EU (although I'm sure they have it) but here in the US you can get the AFD (airport facilities directory) which has lots of info on these kinds of things. Most airports/FOB's now have websites that list their prices as well. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Anything else you think is important to know about possessing and airplane of that type.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems you are looking for a fixed number to a question that does not have an answer like that. You must first identify your mission then you can find a plane to fit the mission profile. You can then look at the prices of other people who have owned that plane and you may find what you seek but you will also find that there is a HUGE deviation in the prices as no two planes are alike.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2017-05-23T03:55:44.610" LastActivityDate="2017-05-23T03:55:44.610" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13682" PostTypeId="2" ParentId="13673" CreationDate="2015-03-30T14:04:57.603" Score="8" Body="&lt;p&gt;The most common failures in planes start with: a &lt;strong&gt;human mistake&lt;/strong&gt; or a &lt;strong&gt;mechanical failure&lt;/strong&gt;. Where, of course, mechanical failures are much more likely to happen on moving parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Satellites have very little moving parts: you get couple servo motors to adjust the angle of your equipment such as the solar panels and the antennas. Both happen in units of full rotations a day. You also often have some small rocket engines to correct the satellites course, but they are rocket engines whose moving parts comprise more or less just one valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a plane, however, you have pieces that move very fast and fluids of all kinds (not only fuel which you need not have on a solar-powered plane, but also lubricants, hydraulics etc.), also very sensitive mechanical sensors whose non-stop operation is crucial for the flight. This all needs to be inspected, oil levels checked, hydraulics checked. Last but not least, the weather in the space is quite calm, compared to the atmosphere. Depending on how high you fly, you meet clouds, storms, birds, temperature changes etc., which all can add to the wear of things and make things require maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure which would be the limiting factor, but I think that either some equipment wouldn't be operational without maintenance, or you would get a mechanical failure of some kind.&lt;/p&gt;&#xA;" OwnerUserId="802" LastActivityDate="2015-03-30T14:04:57.603" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13683" PostTypeId="2" ParentId="13677" CreationDate="2015-03-30T15:30:42.073" Score="12" Body="&lt;p&gt;Over Europe and many other parts of the world, the general rule is that if an aircraft in controlled airspace does not reply to instructions from Air Traffic Control, military jets will be scrambled to intercept the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically you are asking if there are exceptions to that rule. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think there are a few. First of all, ATC will not inform the military of every instruction that is not reacted to; there wouldn't be enough jets. Pilots do miss instructions occasionally, sometimes aircraft are handed of to the wrong frequency by ATC, wrong frequencies are entered into the radio etc. All these things usually sort themselves out in matter of minutes and it would be a waste of resources to scramble. If no contact is established after a certain amount of time, only then the military will be involved. However if an aircraft starts to deviate from earlier acknowledged instructions without reacting on the radio, it is safe to assume that the time to alert the military is considerably shorter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then of course the aircraft must be in range of military jets. An aircraft halfway across the Atlantic is simply too far out for most interceptors so until the aircraft is getting closer to shore I don't think there is much reason to scramble jets.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some more information about loss of communications, causes and prevention  can be found in this &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/111.pdf&quot; rel=&quot;nofollow&quot;&gt;Skybrary briefing note&lt;/a&gt;. For obvious reasons the exact procedures for scrambling military aircraft are not publicly available. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-31T09:01:07.390" LastActivityDate="2015-03-31T09:01:07.390" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13684" PostTypeId="2" ParentId="13677" CreationDate="2015-03-30T15:34:10.093" Score="11" Body="&lt;p&gt;There are &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0604.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;well-defined procedures&lt;/a&gt; for communication loss and even for &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0506.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;interceptions&lt;/a&gt; (at least in the US, but I guess other countries are similar). However those procedures are vague on &lt;em&gt;when&lt;/em&gt; an interception is required:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In conjunction with the FAA, Air Defense Sectors monitor air traffic&#xA;  and could order an intercept in the interest of national security or&#xA;  defense. Intercepts during peacetime operations are vastly different&#xA;  than those conducted under increased states of readiness. The&#xA;  interceptors may be fighters or rotary wing aircraft. The reasons for&#xA;  aircraft intercept include, but are not limited to:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Identify an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Track an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Inspect an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Divert an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Establish communications with an aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see, there are no significant details there and certainly no one is saying that intercepts will &lt;em&gt;always&lt;/em&gt; be ordered. But there are a couple of reasons why it's difficult to say anything more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, it's security-related, and the people who know the real answers won't give them anyway. See &lt;a href=&quot;https://aviation.meta.stackexchange.com/q/258/62&quot;&gt;here&lt;/a&gt; for some related discussion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, as &lt;a href=&quot;https://aviation.stackexchange.com/q/7922/62&quot;&gt;this question&lt;/a&gt; explains, there are various reasons for launching jets: a political gesture, a demonstration of a country's military capabilities, and/or a piece of &lt;a href=&quot;http://en.wikipedia.org/wiki/Security_theater&quot; rel=&quot;nofollow noreferrer&quot;&gt;security theater&lt;/a&gt;. It's probably a safe bet that most developed countries have processes in place for &lt;em&gt;when&lt;/em&gt; to launch an interception, but they certainly aren't public.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-03-30T15:34:10.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13685" PostTypeId="1" CreationDate="2015-03-30T15:44:08.190" Score="0" ViewCount="597" Body="&lt;p&gt;When a pilot leaves the cockpit to go to the toilet should the second pilot lock the door?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me it's mandatory in case of the other pilot is taking in hostage and is forced to tap the code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So can the pilot still in the cockpit can have locked the door and then lose consciousness?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine the pilot goes to toilet and a problem occurs, the plane start to stall for example, and he can't reach the cockpit leaving the other alone to manage the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me the only situation is 3 pilots or never let him goes outside in small trip.&lt;/p&gt;&#xA;" OwnerUserId="7936" LastEditorUserId="609" LastEditDate="2015-03-30T15:50:30.963" LastActivityDate="2015-03-30T17:17:42.673" Title="Is locking the cockpit door from inside is a normal procedure when one pilot leaves?" Tags="&lt;safety&gt;&lt;cockpit&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ClosedDate="2015-03-30T17:19:33.053" ContentLicense="CC BY-SA 3.0" />
  <row Id="13686" PostTypeId="2" ParentId="13685" CreationDate="2015-03-30T15:57:25.747" Score="0" Body="&lt;p&gt;The details of how the door locking system works is described in &lt;a href=&quot;https://aviation.stackexchange.com/q/13566/609&quot;&gt;this question&lt;/a&gt;. It explains that if the pilot inside loses consciousness then the pilot in the cabin can open the door after a delay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;European airlines are putting regulations in place to ensure a pilot is never alone in the cockpit to avoid a repeat of the recent crash. This means calling in a flight attendant to the cockpit while the pilot is on the toilet.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-03-30T15:57:25.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13687" PostTypeId="2" ParentId="13657" CreationDate="2015-03-30T17:11:49.027" Score="5" Body="&lt;p&gt;It does have an effect, look in St-Hubert, they have to work an hour longer in the summer!  That might be true anyway, but when reading times in the CFS there are always adjustments for the time change.  Essentially the airport (or parts thereof) opens and closes at the same local time but the zulu time changes.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TWR St-Hubert 118.4 352.5 (E) 1045-05Z‡ Apr-Oct; 1045-04Z Nov-Mar&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You may think that doesn't happen in Sask., but look-&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TWR Saskatoon 118.3 244.7 (E) 1200-0445Z Mon-Fri Mar 11-Nov 3,&#xA;  1245-0445Z Sat-Sun Mar 11-Nov 3, 1245-0445Z Nov 4-Mar 10&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also have to make adjustments to their times to accommodate traffic from other provinces.  They also work longer in the summer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is from an old CFS I found online, don't land and say I said they would be open.&lt;/p&gt;&#xA;" OwnerUserId="7897" LastActivityDate="2015-03-30T17:11:49.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13688" PostTypeId="2" ParentId="13685" CreationDate="2015-03-30T17:17:42.673" Score="1" Body="&lt;p&gt;For most modern, large commercial passenger planes, there is an automatic lock, which then requires the PNF (Pilot Not Flying and outside of the cockpit) to enter an unlock code, or more usually, for the PF (Pilot Flying, and hopefully &lt;em&gt;inside&lt;/em&gt; the cockpit) to remotely unlock the door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The emergency access code typically sounds a cockpit warning buzzer and has a delayed operation, allowing the PF to override this in case of an unwanted, erm, &quot;visitor&quot;, yet at the same time, allowing access to the PNF in case of PF incapacitation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercially, three pilots (or two pilots and a flight engineer) on each flight are no longer economically viable for almost all airlines.  Indeed, most couldn't host a third person comfortably for the whole flight - jump seats are fine for short bursts, but not for a long-haul flight, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, most airlines are now adapting their cockpit manning procedures to ensure another member of the flight crew (typically a flight attendant) joins the PF before the PNF leaves the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="7939" LastActivityDate="2015-03-30T17:17:42.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13689" PostTypeId="2" ParentId="13657" CreationDate="2015-03-30T17:28:10.680" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Does daylight saving time affect local airspace?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes and No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation Flight plan information, weather, etc. all use Zulu Time (UTC). This provides a single time standard everyone in the world can use, and avoids misunderstandings based on various national rules for &quot;Daylight Saving Time&quot;, &quot;Summer Time&quot;, etc.&lt;br&gt;&#xA;The airline / airport / travel agent / etc. are responsible for properly converting UTC times to the local timezone for passenger convenience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly active times for restricted airspace, TFRs, etc. are all published as UTC times to eliminate any possible ambiguity in this regard. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Not everything is based on UTC however: The (FAA-operated) tower at the field I fly from operates from 0700–2300 &lt;em&gt;Local Time&lt;/em&gt;. When the United States messes with the clocks twice a year the UTC hours of operation/effective hours for the Class D airspace will change to remain aligned with the same &quot;local time&quot; operating period.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-30T17:28:10.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13690" PostTypeId="2" ParentId="13673" CreationDate="2015-03-30T17:45:50.440" Score="4" Body="&lt;p&gt;Other than mechanical or human factors, the other key considerations would be the weather and the season.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weather would affect even a high-flying solar powered aircraft because they descend (albeit slowly) during the night cycle.  In addition, their design requires a very carefully managed flight envelope: an unstable air mass could easily destroy the aircraft. Note that thunderstorms, jetstreams and even mountain wave can reach into daytime flying heights as well.  There needs to be a trade off between how high the aircraft can fly in the thin air and the size, weight and fragility of the resultant design.  This would put the aircraft at eventual risk during one or more phases of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The season (in combination with the aircraft's position) would affect the amount of energy it could receive from the sun.  Whilst a solar powered UAV may fare well in the summer months in the northern hemisphere, it may not be possible to fly it continuously in the winter months, for example.  As most applications are location specific, and typically over industrialised regions, this precludes moving the aircraft to the equator or flying a sinusoidal pattern between the two tropical circles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your mechanical assumptions it would also be worth accounting for ionising solar radiation (which may affect onboard computer and memory chips) and stronger UV light, which is likely to have a degrading effect on most of the materials used to build the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, just a mention that redundancy may be a sensible approach for when there is spare payload and/or energy, but would be less desirable when these were both at a premium.&lt;/p&gt;&#xA;" OwnerUserId="7939" LastActivityDate="2015-03-30T17:45:50.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13692" PostTypeId="2" ParentId="13657" CreationDate="2015-03-30T19:09:06.250" Score="6" Body="&lt;p&gt;Yes it does, some Major international airports, notably SYD, have a curfew in place. Commercial passenger aircraft land between 0600 and 23:00 AEST or face sanctions. This in turn affects patterns in Dubai, Singapore, KL, LAX, DFW etc. This is a &quot;must depart by&quot; issue for some of these. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a politically motivated rule to appease voters in the flight path and is tied to &quot;local&quot; time. Aircraft arriving early are slowed and fly laps over suburbs, sharing the joy.&lt;/p&gt;&#xA;" OwnerUserId="7597" LastActivityDate="2015-03-30T19:09:06.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13693" PostTypeId="2" ParentId="13663" CreationDate="2015-03-30T20:52:25.040" Score="6" Body="&lt;p&gt;The Fédération Aéronautique Internationale (FAI) does no longer accept new records for endurance flights of airplanes and gliders for safety reasons. They used to have such a category until at least the mid 1930s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longest powered, unrefueled, solo flight I was able to find is the circumnavigation of the Earth by &lt;a href=&quot;http://en.wikipedia.org/wiki/Steve_Fossett&quot; rel=&quot;nofollow&quot;&gt;Steve Fossett&lt;/a&gt; in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Virgin_Atlantic_GlobalFlyer&quot; rel=&quot;nofollow&quot;&gt;Virgin Atlantic GlobalFlyer&lt;/a&gt;. After taking of on February 8, 2006, at 12:22 UTC he flew for 76 hours and 45 minutes and travelled an official distance of 41,467 km.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-03-30T22:21:05.747" LastActivityDate="2015-03-30T22:21:05.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13694" PostTypeId="2" ParentId="13677" CreationDate="2015-03-30T23:24:21.070" Score="7" Body="&lt;p&gt;I would answer: No.  In the U.S. there is a &quot;lost comm&quot; procedure which is detailed in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/aim/aim0604.html&quot;&gt;Airman's Information Manual 6-4-1&lt;/a&gt;.  I this procedure, the crew should enter the lost comm code, 7600, into the transponder.  If in radar range, this signals to ATC that the aircrew knows that it's radio has failed, and ATC may presume that the crew will follow normal lost communications procedures.  As long as this is happening, and it looks like procedures are being followed, there is a good chance fighters will stay on the ground.  If, on the other hand, The crew keys in 7500, the hijack code, I would presume chances of a scramble are significantly elevated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the procedures look like this:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In Visual conditions, or if Visual conditions are encountered, land as soon as you can.  &lt;/li&gt;&#xA;&lt;li&gt;In instrument conditions, do your best to follow your flight plan as it was most recently cleared.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;More details are in the manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is interesting that there are a few ways to re-establish communications.  For example, ATC or flight service can utilize the voice feature of available navigation beacons, and may issue an instruction like, &quot;Airline 1234, if you read, turn to heading 150.&quot;  If the crew can pick this up, they may be able to respond with a turn and they can continue from there.  The situation being under control, no need to send up interceptors. &lt;/p&gt;&#xA;" OwnerUserId="182" LastActivityDate="2015-03-30T23:24:21.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13697" PostTypeId="1" CreationDate="2015-03-31T04:06:57.767" Score="9" ViewCount="2846" Body="&lt;p&gt;In the United States, the FAA &lt;a href=&quot;https://aviation.stackexchange.com/a/1685/6919&quot;&gt;requires&lt;/a&gt; certain types of aircraft to have a Flight Data Recorder (FDR) and/or Cockpit Voice Recorder (CVR).  I understand these regulations to apply mostly to civil aviation.  Does it apply to military aircraft as well?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another &lt;a href=&quot;https://aviation.stackexchange.com/q/11369/6919&quot;&gt;question&lt;/a&gt; researched whether fighters &lt;em&gt;have&lt;/em&gt; them or not; my question is whether they are &lt;em&gt;required&lt;/em&gt; to, and for military aircraft in general, not just fighters.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-04-02T00:21:09.233" Title="Are military aircraft required to have black boxes?" Tags="&lt;faa-regulations&gt;&lt;military&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13701" PostTypeId="1" AcceptedAnswerId="13702" CreationDate="2015-03-31T06:23:00.873" Score="16" ViewCount="2853" Body="&lt;p&gt;I have seen the first episode of Revolution yesterday and there are all kinds of airplanes just falling from the sky because of complete loss of electricity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know most if not all modern planes use fly-by-wire systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought about this and the the question occurred:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any still commercial airplanes in use that are still flyable with complete loss of all electric systems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do some commercial airplanes still have mechanical backup mechanisms to manoeuvre?&lt;/p&gt;&#xA;" OwnerUserId="7946" LastEditorUserId="1467" LastEditDate="2016-03-31T13:45:58.447" LastActivityDate="2016-03-31T13:45:58.447" Title="Are there commercial airplanes that are still flyable without any electricity?" Tags="&lt;commercial-aviation&gt;&lt;electrical-system&gt;" AnswerCount="2" CommentCount="13" ClosedDate="2015-03-31T20:46:01.550" ContentLicense="CC BY-SA 3.0" />
  <row Id="13702" PostTypeId="2" ParentId="13701" CreationDate="2015-03-31T06:31:58.253" Score="19" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any still commercial airplanes in use that are still steerable with complete loss of all electric systems? Do some commercial airplanes still have mechanical backup steering mechanisms?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbusdriver.net/airbus_fltlaws.htm&quot;&gt;Yes and Yes.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On most(*) Airbus aircrafts, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In case of a complete loss of electrical flight control signals, the aircraft can be temporarily controlled by mechanical mode.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is called &lt;code&gt;MECHANICAL BACKUP&lt;/code&gt; and is the lowest level of control law (after Normal, Alternate and Direct Laws)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft can be steered:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Pitch control is achieved through the horizontal stabilizer by using the manual trim wheel.&lt;/li&gt;&#xA;  &lt;li&gt;Lateral control is accomplished using the rudder pedals.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilots are notified with:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A red MAN PITCH TRIM ONLY warning appears on the PFD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Both controls require hydraulic power.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that if the aircraft looses BOTH electrical and hydraulic power, is no more controllable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually there are pressurised hydraulic reservoirs that allow to have a minimum of hydraulic power even if there is total loss of electrical power, but if there is substantial damage to the aircraft that has severed the hydraulic lines, this is no more applicable.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;(*): beyond the A320. Functionalities vary in &lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/dglr/hh/text_2007_09_27_A380_Flight_Controls.pdf&quot;&gt;the following manner&lt;/a&gt;: (emphasys mine)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Primary Flight controls: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Back-up Control Logical evolution of A320 / A340 / A340-600 family:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Full Fly-By-Wire, with a “Back-up” as an additional precaution to keep control of the aircraft during &lt;strong&gt;temporary loss of&lt;/strong&gt;:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;all Primary Flight Control computers&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;all Electrical power supply&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;A320 : full FBW controls, mechanical Back-up (Pitch Trim &amp;amp; Rudder)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A340/A330 : like A320, additional Yaw Damper to improve Dutch Roll&#xA;  damping even in Back-up mode (BYDU with hydraulic micro generator)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A340-600 : like A340 for pitch, Rudder becomes fully Electrical (BPS + BCM : Back-up Power Supply + Control Module)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A380 : like A340-600 for Yaw control + BPS+BCM also power: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Electrical Pitch Back-Up (elevators) linked to side-stick &lt;/li&gt;&#xA;  &lt;li&gt;Electrical Roll Back-Up (ailerons) linked to side-stick&lt;/li&gt;&#xA;  &lt;li&gt;Pitch Trim (Wheel is replaced by Switches)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For the A380, in particular:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Active Stability Control functions:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All levels of control laws (Normal, Alternate, “Direct” and even Back-up) include a Yaw and Pitch damping function&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-03-31T07:02:26.063" LastActivityDate="2015-03-31T07:02:26.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13703" PostTypeId="2" ParentId="13701" CreationDate="2015-03-31T06:44:58.027" Score="17" Body="&lt;p&gt;It's not even true that &lt;em&gt;most&lt;/em&gt; airliners use fly-by-wire. Among Airbus and Boeing models, the A320 and beyond use FBW on the Airbus side (note that the A300 was produced until 2007), and the 777 and beyond use it on the Boeing side. This is probably a majority of major commercial aircraft, but it's by no means a &lt;em&gt;vast&lt;/em&gt; majority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among these aircraft, virtually all of them have a backup to the electrical system. On most Airbuses, there is a mechanical backup (which directly triggers certain hydraulic control surfaces); only on the A380 is this absent. The Boeing 777 and up have FBW, but the 777 also has a mechanical backup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, the 737 (one of the most common aircraft worldwide) has pure mechanical reversion -- it's controllable even with total loss of hydraulics, let alone electricity.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="3386" LastEditDate="2015-03-31T07:25:37.520" LastActivityDate="2015-03-31T07:25:37.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13704" PostTypeId="1" AcceptedAnswerId="13705" CreationDate="2015-03-31T06:58:43.493" Score="5" ViewCount="1436" Body="&lt;p&gt;I stumbled across &lt;a href=&quot;http://aeroscraft.com&quot; rel=&quot;nofollow&quot;&gt;this site&lt;/a&gt; when I was searching for info about airships. They have main three products - &lt;del&gt;aerocraft&lt;/del&gt; aeroscraft, airship and aerostat. Aerostat is clear for me somehow. But what is the key difference between &lt;del&gt;aerocraft&lt;/del&gt; aeroscraft and airship?&lt;/p&gt;&#xA;" OwnerUserId="7947" LastEditorUserId="7947" LastEditDate="2015-04-01T05:31:13.537" LastActivityDate="2017-03-26T12:42:56.183" Title="What is the difference between an aeroscraft and an airship?" Tags="&lt;airship&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13705" PostTypeId="2" ParentId="13704" CreationDate="2015-03-31T07:29:50.353" Score="9" Body="&lt;p&gt;Aero&lt;b&gt;s&lt;/b&gt;craft is their brand name. It does not mean anything generally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general terms are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Aircraft&quot; (but not &quot;aerocraft&quot;) means any machine capable of sustained flight in the atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aerostat&quot; rel=&quot;noreferrer&quot;&gt;Aerostat&lt;/a&gt;&quot; is a lighter-then-air aircraft. That is it has large shell filled with gas with lower density than air and uses buoyant force on that for lift. This includes balloons, hot-air or gas filled, tethered balloons and airships.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airship&quot; rel=&quot;noreferrer&quot;&gt;Airship&lt;/a&gt;&quot;, or &quot;dirigible&quot; is an aerostat equipped with propulsion that allows it to move on it's own (as opposed to balloons that are tethered or carried by wind).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-03-31T17:15:02.247" LastActivityDate="2015-03-31T17:15:02.247" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13706" PostTypeId="2" ParentId="3146" CreationDate="2015-03-31T10:13:03.160" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I recall an Air Crash Investigation episode&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeroflot flight 593&lt;/a&gt; Moscow–Hong Kong, Airbus A310-300, Russia, 23 March 1994&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;where the pilot pretended to allow his son to manipulate the controls of an airliner&lt;/strong&gt;,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilot actually allowed his son to manipulate the flight controls. The A310 has a conventional yoke. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The autopilot was engaged at the time, so small movements of the flight controls had no effect. The pilot pretended to his son that he was in full control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large, forceful movements contradicting the autopilot caused the autopilot to relinquish control to the pilot (the autopilot assumes the pilot knows best) - in this case, control over ailerons (but not over pitch, airspeed, altitude, throttles etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots are not dropped into new aircraft without training to understand how use of the controls affect the autopilot. The pilot's actions were reckless and he failed to monitor the childs actions and their effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pzW5B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;A310 cockpit - &lt;a href=&quot;http://www.airport-ostrava.cz/de/page-foto-galerie/galerie-254-cockpit/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;without realising the autopilot had been disconnected&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The appropriate indicator light illuminated to show that there was manual control over ailerons but it seems the pilot was too busy entertaining his child to pay proper attention to flying the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;cavalry charge&quot; audio alert only occurs when the autopilot is fully disengaged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;lights on the instrument panel show what aspects of flight the autopilot is controlling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was actually the child who first noticed that the aircraft was banking!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;resulting in an accident.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In combination with inappropriate actions by panicing pilots.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Despite the struggles of both pilots to save the aircraft, it was later concluded that if they had just let go of the control column, the autopilot would have automatically taken action to prevent stalling, thus avoiding the accident.[11]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Wikipedia)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I'm wondering how commonplace this is?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems to be very uncommon for children and/or other passengers to enter the cockpit midflight and cause a crash.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is this an isolated incident?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No. See &lt;a href=&quot;https://aviation.stackexchange.com/a/3173/1289&quot;&gt;dawg's answer&lt;/a&gt;. It may be the only case on an Airbus. &lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-03-31T10:29:24.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13707" PostTypeId="1" CreationDate="2015-03-31T12:00:56.980" Score="3" ViewCount="729" Body="&lt;p&gt;I want to have a look at air traffic fatalities data, and have found good information on number of accidents, like &lt;a href=&quot;http://aviation-safety.net/statistics/period/stats.php?cat=A1&quot; rel=&quot;nofollow&quot;&gt;this on AviationSafety&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison I want some (world-wide) data on passenger air traffic volume, like number of flights (journeys) per year, or passenger-km per year. So far I couldn't find it. Some good reference? &lt;/p&gt;&#xA;" OwnerUserId="7949" LastEditorUserId="65" LastEditDate="2015-03-31T13:13:27.270" LastActivityDate="2015-03-31T14:12:03.613" Title="Where can I find good data on volume of air traffic?" Tags="&lt;commercial-aviation&gt;&lt;accidents&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13708" PostTypeId="2" ParentId="13707" CreationDate="2015-03-31T13:32:00.317" Score="2" Body="&lt;p&gt;I think extensive world-wide statistics will be very difficult to compile since it would be spread across so many sources. There are  Narrowing it down to Europe and America I think would make it a lot easier...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did a search with reference to ICAO, the International Civil Aviation Organisation (a branch of the UN), but the data appeared to be behind a paywall. The World Bank however does have &lt;a href=&quot;http://data.worldbank.org/indicator/IS.AIR.PSGR&quot; rel=&quot;nofollow&quot;&gt;data&lt;/a&gt; for most countries, again based on ICAO data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some nice and detailed data for America appears can be found at the &lt;a href=&quot;http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/subject_areas/airline_information/index.html&quot; rel=&quot;nofollow&quot;&gt;Bureau of Transportation Statics&lt;/a&gt;, part of the Department of Transportation.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-03-31T13:32:00.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13709" PostTypeId="1" AcceptedAnswerId="13714" CreationDate="2015-03-31T13:35:07.710" Score="3" ViewCount="3635" Body="&lt;p&gt;I read on &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_fuel#Military_jet_fuels&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;JP-1 was an early jet fuel specified in 1944 by the United States government (AN-F-32). ... It was also known as avtur.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is AVTUR the same as JP-1 fuel, and the term &quot;AVTUR&quot; is just a nickname?&lt;/p&gt;&#xA;" OwnerUserId="7777" LastEditorUserId="65" LastEditDate="2015-03-31T14:00:44.730" LastActivityDate="2019-03-31T07:33:12.427" Title="Is AVTUR the same as JP-1 fuel?" Tags="&lt;fuel&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13710" PostTypeId="2" ParentId="13707" CreationDate="2015-03-31T13:57:56.083" Score="3" Body="&lt;p&gt;For $799 you can buy IATA's &lt;a href=&quot;https://www.iata.org/publications/Pages/wats.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;World Air Transport Statistics (WATS)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IATA publish a few summary data values in various reports&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.iata.org/publications/Pages/wats-passenger-km.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scheduled Passenger - Kilometres Flown&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.iata.org/publications/pages/wats-passenger-carried.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scheduled Passengers Carried&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.iata.org/about/documents/iata-annual-review-2013-en.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA Annual Review 2013&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.iata.org/publications/documents/iata-annual-review-2014-en.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA Annual Review 2014&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.iata.org/pressroom/facts_figures/fact_sheets/Documents/industry-facts.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA Statistics&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that I think this is data is only collected from IATA members and much of the data is for western-built jets (figures for other manufacturers are much worse, according to comments in IATA reports)&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Passenger Km&#xA;Total (International + Domestic)&#xA;&#xA;Rank  Airline                   Millions&#xA;1     United Airlines           286,802&#xA;2     Delta Air Lines           277,560&#xA;3     Emirates                  209,377&#xA;4     American Airlines         206,551&#xA;5     China Southern Airlines   147,841&#xA;6     Southwest Airlines        145,124&#xA;7     Lufthansa                 144,236&#xA;8     Air France                136,405&#xA;9     British Airways           130,129&#xA;10    Qantas Airways            110,203&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zmRJY.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2w0dJ.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/hD451.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-03-31T14:12:03.613" LastActivityDate="2015-03-31T14:12:03.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13711" PostTypeId="2" ParentId="13522" CreationDate="2015-03-31T14:19:41.427" Score="4" Body="&lt;p&gt;There is a school of thought that contends that the convergent nozzle is an inefficient version of the convergent -divergent nozzle.  The jet velocity will rise to a maxima at the throat of the nozzle (smallest area) and then exit the nozzle and expand again against atmospheric pressure.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will find that a fixed convergent nozzle would not be used because a fixed nozzle of any sort will be less efficient than a variable geometry nozzle.  The ability to tune the nozzle for local atmospheric pressure, airspeed, and engine throttle setting is key to efficient generation of thrust.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could it be used?  Yes&#xA;However the circumstances where it is the best option are probably so limited as to make it never the right choice.&lt;/p&gt;&#xA;" OwnerUserId="7728" LastActivityDate="2015-03-31T14:19:41.427" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13712" PostTypeId="2" ParentId="13522" CreationDate="2015-03-31T15:42:02.413" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can a supersonic fighter incorporate a convergent nozzle?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It actually exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Panavia_Tornado#Specifications_.28Tornado_GR4.29&quot; rel=&quot;noreferrer&quot;&gt;Panavia Tornado&lt;/a&gt; has a maximum airspeed of Mach 2.2 at 9000m altitude and has variable geometry convergent nozzles (although they work only for the afterburner, while the turbine's nozzle is convergent-divergent):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2zDYv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Photo from &lt;a href=&quot;http://www.airliners.net/photo/Germany---Air/Panavia-Tornado-IDS/0907980/L/&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-03-31T19:11:53.823" LastActivityDate="2015-03-31T19:11:53.823" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13713" PostTypeId="2" ParentId="13677" CreationDate="2015-03-31T15:52:34.873" Score="0" Body="&lt;p&gt;&lt;em&gt;Are military jets always &lt;strong&gt;scrambled&lt;/strong&gt;...&lt;/em&gt;&#xA;Back to the question, &lt;strong&gt;NO&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some regions are protected by armed platforms in continuous orbit. &lt;/p&gt;&#xA;" OwnerUserId="7953" LastActivityDate="2015-03-31T15:52:34.873" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13714" PostTypeId="2" ParentId="13709" CreationDate="2015-03-31T15:54:51.813" Score="7" Body="&lt;p&gt;AVTUR stands for &lt;strong&gt;AV&lt;/strong&gt;iation &lt;strong&gt;TUR&lt;/strong&gt;bine Fuel and is equivalent to JP-1, at least in the UK and in as much as JP-1 no longer exists.  I believe that the US military equivalent is JP8 which is Jet-A1 with additional additives, which differs from commercial Jet-A only by a lower freezing point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.seta-analytics.com/documents/Defstan_91-91_R7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is the relevant NATO Def Stan (Defense Standard)&lt;/a&gt; for Avtur with is the same defstan as for Jet-A1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.exxonmobilaviation.com/AviationGlobal/Files/WorldJetFuelSpecifications2005.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This link&lt;/a&gt; to an Exxon document gives a great deal of information for various aviation fuel oils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.shell.com/global/products-services/solutions-for-businesses/aviation/shell-aviation-fuels/fuels/types/military-jet-fuel-grades.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;From here:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;JP-8 is the military equivalent of Jet A-1 with the addition of&#xA;  corrosion inhibitor and anti-icing additives; it meets the&#xA;  requirements of the U.S. Military Specification MIL-T-83188D. It is&#xA;  the dominant military jet fuel grade for NATO airforces. The UK also&#xA;  have a specification for this grade namely DEF STAN 91-87 AVTUR/FSII&#xA;  (formerly DERD 2453). NATO Code F-34.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastEditorUserId="2176" LastEditDate="2017-07-14T18:08:35.390" LastActivityDate="2017-07-14T18:08:35.390" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13715" PostTypeId="1" AcceptedAnswerId="13716" CreationDate="2015-03-31T16:31:40.250" Score="11" ViewCount="1997" Body="&lt;p&gt;What are the important precautionary measures to take when a flight (either GA or airliners) is operating in extremely cold (e.g. -10°C or below) or extremely hot (e.g. 40°C or above) weather conditions?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1467" LastEditDate="2015-03-31T16:53:30.583" LastActivityDate="2015-03-31T19:49:10.947" Title="Which precautions should I take when flying in very cold / hot weather?" Tags="&lt;safety&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13716" PostTypeId="2" ParentId="13715" CreationDate="2015-03-31T16:31:40.250" Score="11" Body="&lt;h3&gt;Pre-heat the engine&lt;/h3&gt;&#xA;&lt;p&gt;When the engine is cold, the metals may come in contact to each other, which greatly increases engine wear. &lt;a href=&quot;https://aviation.stackexchange.com/questions/347/when-is-pre-heating-a-piston-engine-important-and-how-does-one-pre-heat-correct&quot;&gt;The best way to pre-heat is to use a hangar&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Engine oil&lt;/h3&gt;&#xA;&lt;p&gt;Oil viscosity is closely related to temperature. If the temperature is too low, oil becomes too thick. Thick oil cannot flow around the engine compartments freely. Thin oil, on the other hand, may have reduced lubricating effect. Thus, choosing the correct oil type is important. An oil with lower viscosity may be used in cold climate, and likewise oil with high viscosity in a hot climate.&lt;/p&gt;&#xA;&lt;h3&gt;Cabin heat&lt;/h3&gt;&#xA;&lt;p&gt;Cabin heat can be useful for warming the cabin, however a leakage may lead to carbon monoxide poisoning. Carbon monoxide detectors can be useful in providing an early warning.&lt;/p&gt;&#xA;&lt;h3&gt;De-ice&lt;/h3&gt;&#xA;&lt;p&gt;Ice built up can affect aerodynamic surfaces severely. &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Eagle_Flight_4184&quot; rel=&quot;noreferrer&quot;&gt;In serious cases&lt;/a&gt;, they may cause the wings to lose enough lift and stall. Pitot tubes and engine sensors may also give false readings &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Florida_Flight_90&quot; rel=&quot;noreferrer&quot;&gt;if their de-ice/anti-ice system is not activated&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Density altitude&lt;/h3&gt;&#xA;&lt;p&gt;The density of cold air is greater than normal. Engine damage may be induced by pushing full throttle, which causes the engine to produce &lt;a href=&quot;https://aviation.stackexchange.com/a/81/19&quot;&gt;more power than it is rated&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;In hot air, the density is reduced. This reduces engine performance, resulting in longer takeoff and landing rolls. Aerodynamic performance is also reduced, resulting in a higher TAS (true airspeed) for the same IAS (indicated airspeed). These effects must be taken into consideration in determining whether runway length is sufficient.&lt;/p&gt;&#xA;&lt;p&gt;If there is high terrain near an hot airport, it may be necessary to circle the airport to climb as the plane may not have sufficient climb performance.&lt;/p&gt;&#xA;&lt;h3&gt;Surface friction&lt;/h3&gt;&#xA;&lt;p&gt;In cold conditions, the taxiways and runways are often icy and slippery. Heavy braking should be avoided.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-03-31T16:52:33.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13718" PostTypeId="1" AcceptedAnswerId="13720" CreationDate="2015-03-31T18:04:07.360" Score="12" ViewCount="4361" Body="&lt;p&gt;Cockpit Voice Recorder and Flight Data Recorder's &quot;Underwater locator beacons&quot; &lt;em&gt;only send their position when underwater&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why don't they do so when not underwater?&lt;/p&gt;&#xA;" OwnerUserId="7957" LastEditorUserId="7957" LastEditDate="2015-03-31T20:42:07.067" LastActivityDate="2015-04-01T17:46:58.250" Title="Why don't black boxes send a signal when above water?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13719" PostTypeId="2" ParentId="13522" CreationDate="2015-03-31T18:21:10.763" Score="14" Body="&lt;p&gt;&lt;strong&gt;Short answer: Yes.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A convergent nozzle will not allow supersonic exit speeds of the combustion gasses, but due to their high temperature their speed of sound is considerably higher that that of the surrounding air. For example, at 700°C the speed of sound in air is 625 m/s. Since thrust is mainly determined by the difference in entry and exit speeds of the air flowing through an engine, a higher speed than flight speed is required for positive thrust. Low supersonic flight speeds are entirely possible with a convergent nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Long Answer: Better not.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft crosses the sound barrier, drag increases only slowly since the drag coefficient actually drops. If the design is meant to fly supersonically, which implicates a lot of design adaptions, it makes sense to go for higher supersonic speed; however, this requires both an &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;adjustable intake&lt;/a&gt; and an &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/adjustable-area-jet-engine-nozzles/9666#9666&quot;&gt;adjustable convergent-divergent nozzle&lt;/a&gt;. Both increase efficiency, dramatically so at higher Mach numbers. The simple pitot intake of the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt; is just good enough for Mach 1.6 (above that its efficiency becomes outright awful), but still its F-110 engine has a con-di nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With an adaptable convergent nozzle the exhaust gasses can be accelerated up to their speed of sound, but not more. A narrowing of the flow path will accelerate subsonic flow, but only to the speed of sound. Only a divergent flow path will then accelerate the flow further to supersonic speed. A convergent nozzle will be shorter and lighter, but means throwing away a good deal of useable energy with the hot exhaust gasses. In most cases it would be more efficient to convert the pressure energy of the exhaust gasses into more thrust by accelerating them to supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convergent nozzles only make sense if the aircraft is designed only for short, limited supersonic dashes, but will spend almost all flying time at subsonic speeds. Examples are the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_F-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop F-5E&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Panavia_Tornado&quot; rel=&quot;nofollow noreferrer&quot;&gt;Panavia Tornado&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-03-04T04:30:10.757" LastActivityDate="2020-03-04T04:30:10.757" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13720" PostTypeId="2" ParentId="13718" CreationDate="2015-03-31T18:59:00.857" Score="27" Body="&lt;p&gt;The short answer is that when a plane crashes on land we (generally) have a pretty good idea where to look for the black boxes - there will usually be a relatively clearly defined debris field to search.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a plane goes down in the water there's a lot more ocean to search, and currents can deposit parts of the airframe over a much wider area, so the &lt;a href=&quot;http://en.wikipedia.org/wiki/Underwater_locator_beacon&quot; rel=&quot;noreferrer&quot;&gt;underwater locator beacon (&quot;pinger&quot;)&lt;/a&gt; helps guide people to the debris field.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The longer answer is that sending a signal when you are underwater is relatively easy.  The pinger has a water switch: when it gets wet the water closes an electric circuit and the pinger makes a noise that can be heard on standard passive SONAR gear.&lt;br&gt;&#xA;Water is pretty good at conducting sound waves, so the pings can be heard over a large distance and can guide searchers to the black box (or at least the pinger: sometimes they get ripped off, but they're usually still &lt;em&gt;near&lt;/em&gt; the debris field).&lt;br&gt;&#xA;We get all of that functionality in &lt;a href=&quot;https://i.stack.imgur.com/xQm2H.jpg&quot; rel=&quot;noreferrer&quot;&gt;a fairly small self-contained device&lt;/a&gt; that requires effectively no maintenance (you replace the unit when its battery expires).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sending a signal when you're NOT under water is harder: you can activate the signaling device with a &quot;G Switch&quot; the same way the &lt;a href=&quot;http://en.wikipedia.org/wiki/Distress_radiobeacon#Aviation_.28ELTs.29&quot; rel=&quot;noreferrer&quot;&gt;ELT&lt;/a&gt; is activated, but after that the problems get harder:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You can't use sound (effectively)&lt;br&gt;&#xA;A &quot;pinger&quot; beeping in the air is much less effective than under water - the range would be extremely limited even at very high volumes. Add to that the fact that crash scenes are pretty noisy with firefighting and rescue crews working and the chances of anyone hearing an acoustic beacon on the surface are pretty slim. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You can't use light (effectively)&lt;br&gt;&#xA;A strobe on the black box may work OK in the dark, but it's easily damaged and not terribly effective during the day, or if the recorder is upside-down, in dense foliage, under snow/mud, etc. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Radio locator beacons are problematic&lt;br&gt;&#xA;Radio locator beacons require an antenna - if the antenna is damaged or torn off in the crash the effective range of a radio beacon would be drastically reduced, possibly to the point of being completely ineffective.&lt;br&gt;&#xA;If the antenna remains attached the signal can still be reduced drastically if the box is buried under natural features (dirt) or aircraft debris (aluminum skin).&lt;br&gt;&#xA;(Both of these issues are frequently raised in criticism of ELT technology.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's possible a locator system could be devised that works on the surface, but given the challenges and the fact that the location of the black box is generally known (to within the size of the debris field at least) when an aircraft crashes on the surface there hasn't been much effort invested in this.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, remember that while the recorders are a very valuable part of the investigation process remember that from an investigation standpoint it doesn't matter if you find the black boxes on the first day or the last day of recovery operations:  Finding the recorders will not undo the crash or bring the dead back to life, so if it takes a little longer to find them while sorting through a debris field on the surface it's really not a major problem. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-03-31T18:59:00.857" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13721" PostTypeId="2" ParentId="13522" CreationDate="2015-03-31T19:05:53.037" Score="4" Body="&lt;p&gt;Pilot here, as well as an engineer who made it most of the way to an Airframe and Powerplant technician license at one point in life and worked a lot on nozzles including at the jet Propulsion Laboratory (very fun).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to understand nozzle shapes a fun introduction is to read about the shape that inspired modern rocket (and some jet) nozzles, the &lt;a href=&quot;http://en.wikipedia.org/wiki/De_Laval_nozzle&quot; rel=&quot;nofollow noreferrer&quot;&gt;de Laval nozzle&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's keep in mind that what we want (ignoring for the moment optimization of air volume to feed combustion) is &lt;strong&gt;HIGH SPEED in the OUTGOING JET EXHAUST&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a SUBSONIC flow the air remains compressible and a converging subsonic nozzle increases velocity while pressure and temperature decrease. (There are actually about a dozen subcases here that I'm sure others will yell at me on, so consider that P and T decrease to be an inexcusable simplification on my part to avoid another page of explanation.) So &lt;strong&gt;for a slower exhaust final speed&lt;/strong&gt;, a converging nozzle makes perfect sense. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ideal situation for SUPERSONIC flow is &lt;strong&gt;converging-diverging&lt;/strong&gt; (see the de Laval again) because, for isentropic flow, the &lt;strong&gt;converging portion&lt;/strong&gt; builds energy up to the point of the sonic speed. This sonic point is then put right at the &quot;throat&quot; where converging &lt;strong&gt;becomes diverging&lt;/strong&gt; and the diverging part turns heat and pressure into more speed up to fairly high values of supersonic. Note that a modern jet engine is fairly complicated in air flow and the &quot;throat&quot; may be deep inside the engine and not look like a rocket engine throat at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MhAyg.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For these reasons we would expect to see converging final nozzles on subsonic aircraft like airliners and some fighter jets, while supersonic jets usually have diverging nozzles. If you see a converging nozzle on a supersonic-capable fighter &lt;strong&gt;look at it carefully to see if it is articulated for changing shape in flight&lt;/strong&gt; - which is pretty darn common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said all that, aerospace designers are very clever and injecting fuel (afterburners) can cause non-isoentropic flow if designed for it. So I won't go out and say there aren't any converging nozzle supersonic nozzle jets, but at least now you know why they would be the exception and not the rule :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please feel free to post questions if I skipped something that should be addressed...&lt;/p&gt;&#xA;" OwnerUserId="7688" LastActivityDate="2015-03-31T19:05:53.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13722" PostTypeId="2" ParentId="13715" CreationDate="2015-03-31T19:24:07.693" Score="7" Body="&lt;p&gt;In addition to Kevin's excellent answer, there are a few additional factors I can think of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In colder, denser air, lift is greater for the same aerofoil, angle of attack and airspeed and lower in warmer, less dense air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In piston engined craft with normally aspirated carburettors, the temperature will affect the risk of &lt;a href=&quot;http://en.wikipedia.org/wiki/Carburetor_icing&quot;&gt;carburettor icing&lt;/a&gt; which can be counter intuitive.  At very low temperatures, icing is much less likely than at warmer temperatures since very cold air contains little or no moisture.  In fact, in the UK, carburettor icing is a risk at some power settings throughout the year since there are few days cold enough to be carrying dry air and relative humidity is high for most of the time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the craft I have seen which require carb heating to counter this have an inlet temperature gauge with a green section. The pilot applies heat to keep the gauge in the green which might mean &lt;strong&gt;removing&lt;/strong&gt; heat as the temperature drops.  Heat is only used when needed since it lowers the density of the inlet charge to the engine which reduces available power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference in all of these factors became very apparent to me when learning to fly an R22 helicopter.  On cold, winter days, it was a different machine, climbing like a rocket, greatly reduced throttle setting for a given attitude and speed and even more manoeuvrability than usual.  I remember once almost being in auto-rotation just to descend, she just didn't want to return to earth. Conversely, on hot summer days with my instructor, we sometimes had to do a &lt;a href=&quot;http://en.wikipedia.org/wiki/Translational_lift&quot;&gt;running take off&lt;/a&gt; and would need quite a lot of power in the descent to keep the rate in check.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, most aircraft perform better when it's cold and dry.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-03-31T19:49:10.947" LastActivityDate="2015-03-31T19:49:10.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13723" PostTypeId="1" AcceptedAnswerId="13725" CreationDate="2015-03-31T19:47:54.800" Score="22" ViewCount="63044" Body="&lt;p&gt;Whilst writing an answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/13715/which-precautions-should-i-take-when-flying-in-very-cold-hot-weather/13722#13722&quot;&gt;this question&lt;/a&gt;, I remembered something I don't really understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The partial vacuum in the inlet manifold is caused by the piston descending with the inlet valve open during the &quot;suck&quot; phase of the Otto cycle.  It is this vacuum that causes fuel to be pushed into the intake, the greater the vacuum, the greater the fuel added to the inlet charge and the greater the power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the needle valve is on the manifold side of the throttle butterfly along with the input to the MAP gauge, why does the manifold pressure &lt;strong&gt;increase&lt;/strong&gt; with power?  I would have thought more power, more &quot;suck&quot;, lower pressure; more pressure, less &quot;suck&quot;, less fuel.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm obviously wrong since that's not how it works but why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3313/why-does-manifold-pressure-increase-when-you-turn-on-carb-heat&quot;&gt;The answers to this question&lt;/a&gt; get close but I'm still missing something (and I'm sure will soon be embarrassed by the obviousness of the answer).&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2020-10-08T21:39:21.230" Title="Why does manifold pressure increase with power?" Tags="&lt;piston-engine&gt;" AnswerCount="6" CommentCount="11" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13724" PostTypeId="2" ParentId="13723" CreationDate="2015-03-31T20:03:04.897" Score="5" Body="&lt;p&gt;Manifold pressure is the pressure in the fuel\air mixture between the throttle and the engine. When the throttle is at low power, then it is preventing fuel\air from flowing which causes a reduction in pressure. This is because the engine is trying to pull fuel\air, but throttle is preventing it much like sucking on a straw stuck into thick milkshake. When the throttle is wide open, then the fuel is able to freely flow &amp;amp; you should see normal pressure just like outside (i.e. 29.92).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, the pressure is actually decreased when at low power &amp;amp; at &quot;normal&quot; pressure when at full power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more info check out &lt;a href=&quot;http://www.askacfi.com/421/what-is-manifold-pressure.htm&quot; rel=&quot;noreferrer&quot;&gt;this link&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="3495" LastEditDate="2015-03-31T20:12:47.157" LastActivityDate="2015-03-31T20:12:47.157" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13725" PostTypeId="2" ParentId="13723" CreationDate="2015-03-31T20:31:16.923" Score="12" Body="&lt;p&gt;Manifold pressure is actually a measure of the &lt;em&gt;vacuum&lt;/em&gt; pressure between the throttle and the cylinders. The more the throttle is opened, the closer that manifold pressure returns to atmospheric pressure.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of fuel provided to the engine depends on the pressure difference between the manifold and the throttle body.  The throttle body pressure will decrease as the throttle is increased, because of greater rate airflow across the venturi (faster air -&gt; lower pressure).  The manifold pressure will increase as throttle is increased, due to the greater flow of fuel/air mix into the manifold (greater &lt;em&gt;mass&lt;/em&gt; of air flowing into a fixed volume -&gt; higher pressure).  So the pressure difference will get larger as the throttle is increased.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.avweb.com/features_old/pelicans-perch-15manifold-pressure-sucks&quot; rel=&quot;nofollow noreferrer&quot;&gt;This link&lt;/a&gt; has a pretty good description of what's going on.&lt;/p&gt;&#xA;" OwnerUserId="7752" LastEditorUserId="33692" LastEditDate="2020-05-18T20:36:39.970" LastActivityDate="2020-05-18T20:36:39.970" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="13726" PostTypeId="2" ParentId="13718" CreationDate="2015-03-31T21:16:41.950" Score="11" Body="&lt;p&gt;The premise is inaccurate. Modern aircraft &lt;em&gt;do&lt;/em&gt; output a radio signal when they crash in order to guide search and rescue teams when the crash is over land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, (some? most?) modern aircraft carry &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Distress_radiobeacon&quot;&gt;ELTs&lt;/a&gt;, which activate  after a crash and use a GPS unit (accurate to about 100m) to determine their location. They then transmit this information on the &lt;a href=&quot;https://en.m.wikipedia.org/wiki/406_MHz&quot;&gt;406 MHz&lt;/a&gt; band, which is monitored by satellites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a signal is picked up, search and rescue teams will be notified and provided with a location accurate to about 100 meters. This allows rescue teams to find survivors quite quickly after a crash, which is vital for survival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, as voretaq said, it's not important to find the black boxes very quickly after a crash. Whether it takes 1 day or 10, the investigation will take far longer anyways. The reason we have ELTs is to find survivors. If they happen to be useful for locating the black boxes afterwards, that's a plus.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2015-03-31T21:16:41.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13728" PostTypeId="1" AcceptedAnswerId="13765" CreationDate="2015-03-31T23:21:27.453" Score="13" ViewCount="2847" Body="&lt;p&gt;I saw a TV show once about Japan Airlines flight 123, in which the aft pressure bulkhead ruptured, disabling hydraulics and ripping off the vertical stabiliser. So the flight crashed after some time of flying with up-and-down oscillation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since then, I've also heard of two flights in which the aircraft lost control of flight control surfaces, but pilots guided their crippled plane into a landing using engine throttles only:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;noreferrer&quot;&gt;United Airlines flight 232&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shootdown_incident&quot; rel=&quot;noreferrer&quot;&gt;2003 Baghdad DHL attempted shootdown incident&lt;/a&gt;, in which a cargo plane in Iraq was hit on a wing by a missile&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In principle, could such a method have been used in Japan Airlines flight 123?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In principle, would it be possible to control such a plane by use of cooperating passengers moving around in the cabin, e.g. by instruction of a pilot, to shift the weight balance of the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="7919" LastEditorUserId="22726" LastEditDate="2019-03-13T22:57:47.483" LastActivityDate="2019-03-13T22:57:47.483" Title="What alternative methods are there for controlling a plane when flight control surfaces have failed?" Tags="&lt;accidents&gt;&lt;passenger&gt;&lt;weight-and-balance&gt;&lt;throttle&gt;&lt;redundancy&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13730" PostTypeId="2" ParentId="13728" CreationDate="2015-04-01T00:57:26.493" Score="4" Body="&lt;p&gt;The question here is very much related to the way in which the controls were to stop working. If the surfaces are in a more or less neutral position it would be possible to control the airplane (to an extent) using the engines based on the principal that more thrust would increase speed and create more lift as well as less thrust creating a decent. You could to some extent use differential engine power to turn as well. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In principle, would it be possible to control such a plane by use of cooperating passengers moving around in the cabin, e.g. by instruction of a pilot, to shift the weight balance of the aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Maybe, this depends largely on the plane but basic aircraft training would say yes. This is largely why you have to do weight and balance when you learn to fly. The issue here would gingerly moving everyone around so as not to put the plane in a stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that with Japan Air 123 the vertical stabilizer being blown off was a big issue...&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-01T00:57:26.493" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13731" PostTypeId="2" ParentId="13728" CreationDate="2015-04-01T01:05:48.863" Score="12" Body="&lt;p&gt;As far as I understand, the JAL123 pilots &lt;em&gt;did&lt;/em&gt; use thrust manipulation in an attempt to control their crippled aircraft -- however, Japan's largely mountainous terrain conspired against them, as trying to figure out fly-by-thrust-lever requires a massive quantity of airspace, and unfortunately for JAL123, there was a mountain in the way of that effort.  UAL232 and OO-DLL, on the other hand, both happened over relatively flat terrain, which meant that the aircrews could concentrate on working with their crippled airplanes to get them back on the ground as safely as possible, without having to worry about terrain clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the missing vertical stab didn't help them either, as it meant they had to do much more work to control their airplane.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-04-01T01:05:48.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13732" PostTypeId="1" AcceptedAnswerId="13745" CreationDate="2015-04-01T04:09:31.150" Score="11" ViewCount="798" Body="&lt;p&gt;A number of years ago, I read about a technique for cargo pickup and recovery at remote sites using a low-and-slow-flying plane.  The plane would enter a slow orbit around a point on the ground and lower a bag to the ground on a long (hundreds of feet?  A thousand feet?) line.  Once the bag was down, the plane would maintain its turn around a point so that the line stayed slack and the bag stayed in position.  Cargo (perhaps mail?) could be retrieved from or placed in the bag, then once the transfer was complete, the plane exits the circle and lifts the bag.  I'm a lot less clear on that part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I don't have any idea where I read about this, and haven't been able to find any more descriptions of this.  Can anyone tell me if this technique is real, what it's called, where/when it's been used?&lt;/p&gt;&#xA;" OwnerUserId="3146" LastEditorUserId="30468" LastEditDate="2018-06-05T00:10:29.873" LastActivityDate="2020-07-03T01:51:32.957" Title="Where can I find more about a cargo pickup technique that doesn't require landing the plane?" Tags="&lt;general-aviation&gt;&lt;bush-flying&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="13733" PostTypeId="1" AcceptedAnswerId="13735" CreationDate="2015-04-01T04:13:37.450" Score="11" ViewCount="3004" Body="&lt;p&gt;For example, the CVR records only about 2 hours of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overwriting important data must be avoided, and thus the recorders should know if a catastrophe has happened. Then they can stop recording (to protect the already recorded data from overwriting), and start signaling the rescue team.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the logic used to stop recording?&lt;/p&gt;&#xA;" OwnerUserId="7794" LastEditorUserId="97" LastEditDate="2015-04-01T05:17:42.217" LastActivityDate="2015-04-01T14:22:45.530" Title="How does a CVR / FDR determine when to stop recording?" Tags="&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;search-and-rescue&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13735" PostTypeId="2" ParentId="13733" CreationDate="2015-04-01T05:00:21.033" Score="17" Body="&lt;p&gt;The CVR and FDR have impact switches to stop recording when they experience high acceleration. In incidents and accidents that don't involve high enough acceleration, the plane remains intact enough for the boxes to be immediately found and switched off manually. In more serious crashes, the boxes stop recording because of the physical destruction of everything but the memory units (only the memory units are built to survive crashes).&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-01T05:00:21.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13736" PostTypeId="2" ParentId="13728" CreationDate="2015-04-01T05:27:42.773" Score="7" Body="&lt;p&gt;As others have stated, it is possible to control a plane using throttles alone, assuming the control surfaces are largely neutral and the plane is at an stable attitude (e.g. not spinning or stalling):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To climb, increase throttle of all engines&lt;/li&gt;&#xA;&lt;li&gt;To descent, decrease throttle of all engines&lt;/li&gt;&#xA;&lt;li&gt;To turn, decrease throttle of engines on the inner side of the turn&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Such feat would be very difficult as flight crews receive no training of such control methods.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On a large airliner, shifting weights would &lt;a href=&quot;https://aviation.stackexchange.com/a/3074/3386&quot;&gt;produce little effect&lt;/a&gt;, since the weight of passengers contribute only a very small portion of the entire weight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;NASA has already shown that it is technically possible to develop a &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/88293main_H-1911.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;system to automatically control a plane using throttles&lt;/a&gt;. Not only does the system provides stable and acceptable approaches and landings, it was also tested in unusual attitudes and at speeds 100 knots above approach speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to why this kind of system is not implemented across commercial airliners, &lt;a href=&quot;https://aviation.stackexchange.com/a/11466/3386&quot;&gt;the usual answers&lt;/a&gt; apply...&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-01T17:05:42.940" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13737" PostTypeId="2" ParentId="13733" CreationDate="2015-04-01T05:34:55.903" Score="9" Body="&lt;p&gt;In the United States, CVRs and FDRs have a &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/23.1457&quot;&gt;10 minute (+/- 1 minute) battery requirement&lt;/a&gt; to allow any available post-crash voice and data to be recorded, with power removed once a timer limit is reached.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I'm not familiar with the internals of the FDR, simple circuitry could trigger the timer to start based on current flow from the battery, if not for an acceleration-based impact sensor suggested.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-04-01T05:34:55.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13738" PostTypeId="1" CreationDate="2015-04-01T05:38:37.557" Score="24" ViewCount="28099" Body="&lt;p&gt;Just a random thought I had: the weather gives a jet's paint job a battering; meaning they need to be resprayed approximately once every 5-10 years. &lt;sup&gt;(See &lt;a href=&quot;https://aviation.stackexchange.com/q/9112/65&quot;&gt;How often is a passenger jet aircraft painted?&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Roughly what might a paint job for a 777 like the one shown in the YouTube video below, cost an airline?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus: I believe afterwards that the weight of the plane has to be recalculated, so as not to affect &lt;a href=&quot;/questions/tagged/weight-and-balance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;weight-and-balance&amp;#39;&quot; rel=&quot;tag&quot;&gt;weight-and-balance&lt;/a&gt;. How is this calculation done?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/T3RRPQ_Csss?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2020-06-25T21:44:19.473" Title="How much does it cost to give an airliner a fresh coat of paint?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;&lt;livery&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13739" PostTypeId="2" ParentId="13732" CreationDate="2015-04-01T08:02:51.977" Score="3" Body="&lt;p&gt;I don't know the name of the technique, but I know Mission Aviation Fellowship  pilots used it in Ecuador in the 1950's. You can achieve a similar effect by whirling a the end piece of dog-chain or similar hanging from your hand around in small circles. The chain will form a bow shape, and the bottom will stay roughly in the same place.  Hand = plane, rope = chain... put the bucket on a swivel... Changes in speed or hand orbit can lift the end of the chain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wish I could fly like that... &lt;/p&gt;&#xA;" OwnerUserId="7487" LastActivityDate="2015-04-01T08:02:51.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13740" PostTypeId="2" ParentId="13733" CreationDate="2015-04-01T08:10:13.553" Score="4" Body="&lt;p&gt;In crash the last two hours before the crash is most important, so the recorder always recording and stopping when the plane crashes either because of crash sensor or simply due to loss of power and input as the wires leading to it are torn by the impact forces is the right thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in some &lt;em&gt;incidents&lt;/em&gt;¹ the data would also be useful. When the crew realizes something occurred that needs to be reported as incident, they are supposed to pull the circuit breakers after landing and tell the appropriate safety board to come for the data (which must be done before next flight). Alternatively if the aircraft is equipped with &lt;a href=&quot;http://en.wikipedia.org/wiki/Quick_access_recorder&quot; rel=&quot;nofollow&quot;&gt;quick access recorder&lt;/a&gt;² they can instead preserve those data, which can be done by any maintenance worker, so the plane can be dispatched again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However sometimes the crew fails to realize they should preserve the data (or fail to report the incident altogether and it may be reported by someone else like another crew, traffic controller, maintenance etc.) and get scolded for it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Incident is any occurrence in which safety margins were reduced, but nobody was hurt and there was no or only small damage (with damage to engines or landing gear always considered small). The kind of incident where investigators would most want to have CVR and FDR data and don't always get them is TCAS activations (near misses); they generally have ATC voice recordings and radar tracks, which ATC records in much longer loop, but the on-board recorders often get overwritten either before the planes land or because the crews fail to preserve them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² The quick access recorder is not crash-worthy and not mandatory, but most airliners have it these days. It usually has longer recording loop and records more parameters, but the main advantage is that any mechanic with portable computer can download the data in couple of minutes and the aircraft can be dispatched again instead of waiting for the safety board investigator to come around.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-04-01T14:22:45.530" LastActivityDate="2015-04-01T14:22:45.530" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13741" PostTypeId="1" AcceptedAnswerId="13743" CreationDate="2015-04-01T10:04:45.280" Score="12" ViewCount="2189" Body="&lt;p&gt;What is the correct terminology for the name of the aircraft instrument that looks like this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KJ2oI.png&quot; alt=&quot;guage&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7964" LastEditorUserId="3386" LastEditDate="2019-12-20T06:54:14.793" LastActivityDate="2019-12-20T06:54:14.793" Title="What is the correct name for this ILS Indicator?" Tags="&lt;landing&gt;&lt;aircraft-systems&gt;&lt;terminology&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13742" PostTypeId="1" AcceptedAnswerId="13747" CreationDate="2015-04-01T10:17:47.093" Score="7" ViewCount="2110" Body="&lt;p&gt;According to regulations and recommendations from the FAA, ICAO or other aviation organisations, what types of aircraft are required to carry &lt;a href=&quot;https://en.wikipedia.org/wiki/Distress_radiobeacon#ELT_sub-classification&quot;&gt;Automatic Fixed Emergency Location Transmitters (ELT(AF))&lt;/a&gt; devices? In particular, is it required of commercial transport airliners?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAA (and I guess other aviation organisations/regulators) group aircraft into several categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;General Aviation (GA) - personal aircraft etc.&lt;/li&gt;&#xA;&lt;li&gt;Business Aviation - executive jets etc&lt;/li&gt;&#xA;&lt;li&gt;Commercial Air Transport / Public Transport - Scheduled passenger airliners etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;AOPA &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-Emergency-Locator-Transmitters-ELTs&quot;&gt;say&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ELTs are emergency transmitters that are carried aboard most &lt;strong&gt;general aviation&lt;/strong&gt; aircraft in the U.S.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(my emphasis) - note GA, not all aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;CAA &lt;a href=&quot;https://www.caa.co.uk/docs/1672/srg_gad_Appendix%208b%20revised.pdf&quot;&gt;refer to ICAO Annex 6&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aeroplanes - ICAO Annex 6, Part II&lt;br&gt;&#xA;  6.12.3 From 1 January 2005, all aeroplanes operated on extended flights over water as described in &#xA;  6.3.3 b) and when operated on flights over designated land areas as described in 6.4 shall be &#xA;  equipped with one automatic ELT. [i.e. designated KK(ii) in the Air Navigation Order]  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6.12.4 Recommendation. - All aeroplanes should carry an automatic ELT. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But I can't find an annex mentioning ELTs at www.icao.int.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, I'm not sure whether all airliners are required to carry ELT(AF)s and if so, by whom.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="65" LastEditDate="2015-04-01T13:32:54.803" LastActivityDate="2015-04-01T15:38:13.217" Title="Which types of aircraft are required to carry ELTs?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13743" PostTypeId="2" ParentId="13741" CreationDate="2015-04-01T10:19:06.660" Score="14" Body="&lt;p&gt;That is the course deviation indicator, or CDI.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="14" LastEditDate="2015-04-01T13:38:49.963" LastActivityDate="2015-04-01T13:38:49.963" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13745" PostTypeId="2" ParentId="13732" CreationDate="2015-04-01T13:26:35.577" Score="12" Body="&lt;p&gt;See the notes on &lt;a href=&quot;http://en.wikipedia.org/wiki/Pylon_turn&quot; rel=&quot;noreferrer&quot;&gt;this page&lt;/a&gt; under the &quot;Delivery&quot; section. Looks like its formally called &quot; long-line loiter&quot;. There is a brief note on it &lt;a href=&quot;http://wordpress.mrreid.org/2014/04/14/pylon-turns-and-long-line-loitering/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and a US Patent &lt;a href=&quot;http://www.google.com/patents/US3724817&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/749518.pdf&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; manual from the 70's that seems to show how to do it and some related research on it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice image of the maneuver &#xA;&lt;img src=&quot;https://i.stack.imgur.com/J944p.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-01T13:26:35.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13746" PostTypeId="2" ParentId="13741" CreationDate="2015-04-01T14:02:54.240" Score="16" Body="&lt;p&gt;That image is a basic representation of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Course_deviation_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;course deviation indicator&lt;/a&gt;, as mentioned &lt;a href=&quot;https://aviation.stackexchange.com/a/13743/65&quot;&gt;by Steve H&lt;/a&gt;. An actual gauge would look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r42zu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r42zu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.tghairportshop.com/v/vspfiles/photos/MD222-406-2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your image, it shows that the aircraft needs to correct to the left and a little upwards, so that it will be on the glideslope as shown here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TJy9R.png&quot; alt=&quot;ILS Landing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-01T14:02:54.240" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13747" PostTypeId="2" ParentId="13742" CreationDate="2015-04-01T15:07:05.307" Score="5" Body="&lt;p&gt;Everything you need to know (at least in the USA) is &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.207&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding airliners, it appears that they are carved out of the general requirement to have an ELT in 91.207.f.2.   I guess that makes some sense.  If you're flying a scheduled flight, presumably we should be able to find the plane, since we know the takeoff time and approximate airspeed, and we have radar tracking by ATC/ARTCC.  Unscheduled (especially VFR) flights are where things get dicey.&lt;/p&gt;&#xA;" OwnerUserId="6840" LastEditorUserId="6840" LastEditDate="2015-04-01T15:38:13.217" LastActivityDate="2015-04-01T15:38:13.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13748" PostTypeId="2" ParentId="13738" CreationDate="2015-04-01T15:19:23.003" Score="0" Body="&lt;p&gt;The cost depends on a lot of factors, how many planes, how many colors, how desperate the manufacturer is for your business or if you have your own paint shop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But given the care that must be taken to use the correct paint, the correct solvents, dispose of everything and the FAA requirement that the paperwork for the job must weigh more than the paint - I'm guessing several $10K.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing have some data on the amount of paint and if you should &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html&quot; rel=&quot;nofollow&quot;&gt;paint or polish&lt;/a&gt; including the fact that the paint scheme on a 747 weighs nearly 0.5Ton &lt;/p&gt;&#xA;" OwnerUserId="1576" LastActivityDate="2015-04-01T15:19:23.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13749" PostTypeId="1" CreationDate="2015-04-01T15:20:15.337" Score="0" ViewCount="468" Body="&lt;p&gt;One book characterized the &lt;a href=&quot;http://en.wikipedia.org/wiki/Harbin_Y-11&quot; rel=&quot;nofollow&quot;&gt;Harbin Y-11&lt;/a&gt; as a &quot;successor&quot; aircraft to a design based on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-2&quot; rel=&quot;nofollow&quot;&gt;Antonov An-2&lt;/a&gt;, however, it looks completely different than the An-2, which is a single-engine aircraft. Is the Harbin Y-11 a fully indigenous Chinese design with no significant elements copied from some other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-04-01T15:23:38.283" LastActivityDate="2015-04-05T13:48:40.043" Title="Is the Harbin Y-11 a fully indigenous Chinese design?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13750" PostTypeId="1" AcceptedAnswerId="13759" CreationDate="2015-04-01T16:29:24.133" Score="8" ViewCount="2432" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/q/13742/1289&quot;&gt;this earlier question&lt;/a&gt; I tentatively assume that GA means civil aircraft operations other than scheduled passenger transport - what I think of as &quot;airliner&quot; operation though it could include quite small aircraft operating a scheduled fare-paying passenger service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has been suggested to me that GA can sometimes or often be used to mean all aviation in general - perhaps in some contexts more than others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had thought that most people here used GA to mean aircraft operations other than scheduled service, but now I have my doubts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is there an authoritative definition of GA in the USA (and elsewhere, or worldwide) or is it a vague and varyingly interpreted general phrase that I should avoid to prevent misunderstanding?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-04-01T18:08:06.883" Title="Is &quot;General Aviation&quot; a well-defined term in the US, in the EU and/or elsewhere?" Tags="&lt;terminology&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13751" PostTypeId="2" ParentId="13749" CreationDate="2015-04-01T16:34:36.797" Score="0" Body="&lt;p&gt;After some research it appears the Y-11 is an independent design based on the Soviet &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-28&quot; rel=&quot;nofollow&quot;&gt;Antonov An-28&lt;/a&gt; with various significant modifications. The design appears to be a scaled down version of the An-28. Certain elements such as the undercarriage and wing supports are identical.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-04-01T16:34:36.797" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13752" PostTypeId="2" ParentId="13723" CreationDate="2015-04-01T16:53:20.617" Score="1" Body="&lt;p&gt;I'm answering my own question since the existing answers are good, but do miss a key point in my question which ultimately was the source of my confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mistakenly thought that the fuel needle valve is on the manifold side of the butterfly.  Therefore, I could not understand why more vacuum (less power) did not result in more fuel (more power).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is that the valve is on the intake side of the butterfly and therefore, the more open the butterfly, the lower the pressure on the intake and therefore, the more fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, increasing throttle opens the butterfly which lets more air into the engine faster, which causes a drop in pressure (because of the venturi) in the intake which draws more fuel.  Sorted!&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-04-01T16:53:20.617" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13753" PostTypeId="2" ParentId="13750" CreationDate="2015-04-01T16:53:27.190" Score="5" Body="&lt;p&gt;The term &quot;General Aviation&quot; is used differently by different organisations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be best to either avoid it or only use it where it's meaning will be clear to international or non-expert readers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From what I've read, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Use vs Type&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These sorts of classification apply to the &lt;em&gt;use&lt;/em&gt; (i.e. &quot;operation&quot;) rather than to the aircraft &lt;em&gt;type&lt;/em&gt; (make and model) - you could use a 737 as a personal airplane and your use would not be governed by regulations that apply to 737s operated by typical airlines for scheduled passenger transport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FAR lore&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read people say that, in the USA, GA means anything under FAR 91 and FAR 135 but scheduled airliners come under FAR 121 (I may have the numbers wrong, please correct)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;AOPA&lt;/strong&gt; &lt;a href=&quot;http://www.aopa.org/letsgoflying/ready/steps/whatis.html&quot; rel=&quot;noreferrer&quot;&gt;say&lt;/a&gt; &quot;General aviation (GA) is all civilian flying except scheduled passenger airlines.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ICAO&lt;/strong&gt;  &lt;a href=&quot;http://www.icao.int/Meetings/STA10/Documents/Sta10_Wp007_en.pdf&quot; rel=&quot;noreferrer&quot;&gt;define general aviation&lt;/a&gt; as all civil operations other than scheduled air services (plus a bit of hand-waving)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Transport Canada&lt;/strong&gt; &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/opssvs/secretariat-terminology-glossary-215.htm#general_aviation&quot; rel=&quot;noreferrer&quot;&gt;say&lt;/a&gt; &quot;General aviation (GA) is all civil aviation operations other than scheduled air services and non-scheduled air transport operations for remuneration or hire&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FAA&lt;/strong&gt; divide &lt;a href=&quot;http://www.faa.gov/airports/planning_capacity/passenger_allcargo_stats/categories/&quot; rel=&quot;noreferrer&quot;&gt;airport operation&lt;/a&gt; into Commercial Service, Cargo Service, Reliever and everything else &quot;commonly described as General Aviation Airports&quot;. But I couldn't find an FAA definition that applied specifically to the aircraft (or to aircraft operations other than at an airport).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EASA&lt;/strong&gt; &lt;a href=&quot;https://www.easa.europa.eu/easa-and-you/aviation-domain/general-aviation/operations-general-aviation&quot; rel=&quot;noreferrer&quot;&gt;seem to define&lt;/a&gt; operations primarily into Commercial Air Transport (CAT) and Non-Commercial (NC) and use the phrase &quot;general aviation&quot; in a more general all-encompassing sense.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-04-01T16:53:27.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13754" PostTypeId="2" ParentId="13750" CreationDate="2015-04-01T17:01:21.143" Score="7" Body="&lt;p&gt;The FAA does not include a definition of General Aviation in CFR 14 (aka Federal Aviation Regulations) Part 1 (General Definitions and Abbreviations), but, from a functional perspective, in the US, GA is generally used to refer to any civilian operations falling outside of Part 121 and some Part 135 operations (Commuter and Charter Operations - regional feeders have and may still operate under this section if they can meet the requirements, as it is more relaxed and easy to comply with than part 121).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to the FARs, it's important to remember that Part 91 covers ALL types of flight operations UNLESS its provisions are EXPLICITLY overriden by another paragraph (as would be the case with an air carrier's Operating Specifications, part 121, 135, and other sections dealing with more specialized aerial applications). Part 119 also deals, in a very general sense with conducting flight operations for compensation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;IMO, you're not likely to go wrong using the term to refer to everything civilian outside of scheduled carrier and medium/large cargo operations (e.g. Atlas, Evergreen, FedEx, UPS). The caveat is, of course, that GA operations are so diverse that this is more of an &quot;everything else&quot; category rather than the much clearer images conjured up by a flag/commutter/regional carrier or a large cargo operator. If you're unclear about whether a specific application or air operator falls under GA, go ahead and ask.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA division of airports is more likely meant to reflect that certain airports have certain primary intended purposes (e.g. many of the nation's largest airports do not allow Part 91 operations, only air carriers) and may require certain types of infrastructure in order to allow them to perform those roles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, using a 737 as a personal plane under Part 91 would fall under GA - Boeing even makes a specialized version just for that, see the BBJ.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-04-01T17:01:21.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13755" PostTypeId="2" ParentId="13697" CreationDate="2015-04-01T17:35:44.293" Score="2" Body="&lt;p&gt;Military aircraft need not adhere to FAA regulations. Modern military aircraft with digital controls have black boxes, older ones may not.&lt;/p&gt;&#xA;" OwnerUserId="7948" LastEditorUserId="774" LastEditDate="2015-04-02T00:21:09.233" LastActivityDate="2015-04-02T00:21:09.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13756" PostTypeId="2" ParentId="13697" CreationDate="2015-04-01T17:36:02.463" Score="2" Body="&lt;p&gt;No. The FAA has no enforcement ability over the US military.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as airworthiness and certification, the Federal Aviation Act, Section 610, specifically states that its provisions only apply to &quot;air commerce&quot; and &quot;civil&quot; aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-04-01T17:53:39.630" LastActivityDate="2015-04-01T17:53:39.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13758" PostTypeId="1" AcceptedAnswerId="13761" CreationDate="2015-04-01T18:02:19.170" Score="9" ViewCount="1129" Body="&lt;p&gt;I was wondering if any of the (E)GPWS callouts would make the autopilot disconnect? &#xA;If the Alpha Protection is active (like in &lt;a href=&quot;http://avherald.com/h?article=47d74074&quot;&gt;Bilbao, 2014&lt;/a&gt;) would it disconnect? That would give PF full control of the aircraft and could help to recover from the upset, correct?&lt;/p&gt;&#xA;" OwnerUserId="424" LastEditorUserId="19" LastEditDate="2015-04-01T18:55:52.117" LastActivityDate="2015-04-01T19:35:13.300" Title="Does autopilot disconnect when a danger alarm like GPWS triggers?" Tags="&lt;autopilot&gt;&lt;aircraft-systems&gt;&lt;gpws&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13759" PostTypeId="2" ParentId="13750" CreationDate="2015-04-01T18:02:59.757" Score="6" Body="&lt;p&gt;In common parlance, &quot;General Aviation&quot; typically means &quot;not-airline&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;, the FAA now defines General Aviation as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;That portion of civil&#xA;  aviation that does not include scheduled or&#xA;  unscheduled air carriers or commercial space&#xA;  operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and it gives the ICAO definition:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All civil aviation&#xA;  operations other than scheduled air services and&#xA;  nonscheduled air transport operations for remuneration&#xA;  or hire.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Both these definitions are closely tied to commercial operations, and they go out of their way to point out that non-scheduled air carriers are NOT general aviation. Note that &quot;civil aviation&quot; would mean &quot;not military&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically the term has been very colloquial, and to some extent you will still find different definitions from everyone. However, IMHO these are the most clear definitions available.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-04-01T18:08:06.883" LastActivityDate="2015-04-01T18:08:06.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13760" PostTypeId="2" ParentId="13758" CreationDate="2015-04-01T18:45:35.343" Score="6" Body="&lt;p&gt;No, the EGPWS is a &lt;em&gt;warning&lt;/em&gt; system, and does not typically interface with the autopilot. The first step in reacting to EGPWS (or most TCAS) warnings is to disconnect the autopilot &amp;amp; autothrottles and fly manually, but this isn't accomplished by the EGPWS itself.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-01T18:45:35.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13761" PostTypeId="2" ParentId="13758" CreationDate="2015-04-01T18:46:27.447" Score="10" Body="&lt;p&gt;This is the Quick Reference Handbook procedure from an old A320 training manual. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jo9gc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;(The EGPWS procedure is a memory item, pilot's are not expected to look this page up when they encounter a EGPWS warning)&lt;/sub&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first two sub items answer your questions. The autopilot needs to be switched off manually and the instruction is to &lt;code&gt;pull up to full back stick and maintain&lt;/code&gt;. The Alpha protection will prevent the aircraft from stalling, that is why the stick can be maintained at full back deflection. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus' safety magazine &lt;a href=&quot;http://www.airbus.com/support/publications/?eID=maglisting_push&amp;amp;tx_maglisting_pi1%5BdocID%5D=17429&quot; rel=&quot;noreferrer&quot;&gt;FAST #23&lt;sup&gt;(PDF)&lt;/sup&gt;&lt;/a&gt; giving guidance on flying protected aircraft, specifically advices pilots to apply full backward stick deflection in GPWS situations since the alpha protection will prevent the aircraft from stalling and the resulting flight path is the most effective way away from danger. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate a possible the effects of Alpha protection in an (E)GPWS situations, let's go to Bilbao again, but now in &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/335.pdf&quot; rel=&quot;noreferrer&quot;&gt;March 2001&lt;sup&gt;(PDF)&lt;/sup&gt;&lt;/a&gt;. An A320 on final approach encountered a wind shear causing the aircraft to descent fast. This caused the GPWS to trigger a warning. The pilot applied TOGA power and back stick deflection, but the Alpha protection predicted the aircraft to stall and prevented a higher nose attitude. As a result the aircraft didn't stall but crash landed on runway threshold. This accident demonstrates that the GPWS does not affect the flight envelope protection system. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-04-01T19:35:13.300" LastActivityDate="2015-04-01T19:35:13.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13762" PostTypeId="1" AcceptedAnswerId="13767" CreationDate="2015-04-01T19:32:27.737" Score="25" ViewCount="12753" Body="&lt;p&gt;If I recall correctly, the best competition gliders have a L/D ratio as high as 60:1. What imposes this limit? Is there a maximum theoretical L/D ratio, or could sufficiently advanced materials allow a glider with a L/D ratio of, say, 200:1?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2019-08-10T19:32:13.563" Title="Is there a maximum lift to drag ratio?" Tags="&lt;aerodynamics&gt;&lt;glider&gt;&lt;lift&gt;&lt;drag&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13763" PostTypeId="2" ParentId="13762" CreationDate="2015-04-01T19:51:02.857" Score="1" Body="&lt;p&gt;Loosely speaking, L/D ratio is limited by the aspect ratio of the wing (its length to its chord width) and the friction of the wing surface (which is why frost/ice on the wing is a bad thing -- it dramatically increases wing friction).&lt;/p&gt;&#xA;" OwnerUserId="6840" LastActivityDate="2015-04-01T19:51:02.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13764" PostTypeId="1" AcceptedAnswerId="13766" CreationDate="2015-04-01T19:52:42.023" Score="13" ViewCount="5700" Body="&lt;p&gt;I've heard the claim repeated many times that some modern fighter jets have an installed thrust greater than their weight, so theoretically they could accelerate straight up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never actually heard of this being done, however. It sounds useful, though, especially on the deck of an aircraft carrier. Imagine: we could take out the whole catapult system, and replace it with some sort of a system to pick up an aircraft and turn it vertical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this not done?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="1696" LastEditDate="2018-04-25T21:38:34.030" LastActivityDate="2018-04-25T22:14:49.453" Title="Why don't fighter jets take off vertically?" Tags="&lt;takeoff&gt;&lt;fighter&gt;&lt;jet&gt;&lt;aircraft-carrier&gt;&lt;vtol&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13765" PostTypeId="2" ParentId="13728" CreationDate="2015-04-01T20:16:55.487" Score="10" Body="&lt;p&gt;Control means to be able to vary the forces which act on an airplane, both longitudinally and vertically. Ideally, any variation will create an immediate feedback, so the pilot can &quot;feel&quot; how much more action is needed for the desired change. If, however, the variation of forces builds up slowly, the dynamic answer of the airplane will make the closing of the feedback loop harder to achieve. The pilot might either overcontrol and get into an oscillation, or he/she will be too careful, and the desired change never happens or happens too slowly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regular control surfaces are small, so they can move quickly, and their forces act on a long lever arm, so the control effect is large. Also, control surfaces change lift proportional to their deflection, so predicting the consequence of an input is easy and the feedback can be felt immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the primary control surfaces are ineffective, several ways of control still exist. I will list them in order of reaction speed:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The elevator can be replaced by:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pitch trim,&lt;/li&gt;&#xA;&lt;li&gt;Wing flaps,&lt;/li&gt;&#xA;&lt;li&gt;Thrust variation, if the engines sit above or below the longitudinal axis of inertia,&lt;/li&gt;&#xA;&lt;li&gt;Weight shifting, if fuel can be moved between tanks or payload can be shifted longitudinally.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The last two options work very slowly, and while they can be used to limit sink speed, it will be extremely hard to avoid overcontrol and oscillations. Situations which need precise pitch control like landings are impossible to master for an unprepared human pilot when only such crude means of control remain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The rudder can be replaced by:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rudder trim,&lt;/li&gt;&#xA;&lt;li&gt;Ailerons plus pitch control in case of agile aircraft with low aspect ratio,&lt;/li&gt;&#xA;&lt;li&gt;Asymmetric spoiler (if available),&lt;/li&gt;&#xA;&lt;li&gt;Asymmentric thrust.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Again, the last option is rather slow and cannot be used for precise directional control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The ailerons can be replaced by:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rudder plus dihedral effect,&lt;/li&gt;&#xA;&lt;li&gt;Asymmetric spoiler (if available),&lt;/li&gt;&#xA;&lt;li&gt;Sideways fuel pumping.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here again the last option is too crude and too slow for maneuvering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is otherwise undamaged, and the flight dynamics are well known, a specially programmed autopilot could fly an aircraft even when using the last listed options, because it can much better predict than a human pilot how much effect its actions will have. Humans rely on a feedback loop for control, and this is not working anymore if the reaction time of the system is far above its eigenfrequencies of motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the &quot;if&quot;: How likely will it be that only all control surface actuators have failed, but the aircraft is intact otherwise? In most cases, the control failure is a consequence of another failure which will alter the dynamic response such that an autopilot would be unprepared. There are experimental autopilots which can adapt, but they are only used by the military so far.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the loss of most of its tail section, JAL123 would have been hard to control even if the equivalent of full rudder authority would have been given to the pilots. With thrust only, fighting the inevitable dutch roll motion by hand is impossible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-03T05:37:33.613" LastActivityDate="2015-04-03T05:37:33.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13766" PostTypeId="2" ParentId="13764" CreationDate="2015-04-01T20:25:27.940" Score="25" Body="&lt;p&gt;They can climb vertically, but this works best if they are several tons below their maximum take-off mass. Fighter jet engines need a lot of fuel, and at the beginning of the flight the aircraft will be too heavy for vertical climb. Also, the landing gear would need to be rearranged if the plane is to take off from any airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a thrust/weight ratio slightly above 1 at maximum take-off mass will not be enough, because the aircraft needs some airspeed for its control surfaces to become effective. If no thrust vectoring is installed, the aircraft will be uncontrollable in its initial ascent. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot; rel=&quot;noreferrer&quot;&gt;Harrier VTOL jet&lt;/a&gt; uses bleed air which is ducted to nozzles at the extreme ends of fuselage and wing for low-speed attitude control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is conceivable that the fighter will hang vertically on a wall, with its wheels locked in clutches which will release it when the needed thrust is reached. With thrust vector control the aircraft could be controlled over the full trajectory until it transits to horizontal flight, and could even land vertically. But this would need specially prepared airfields and use much more fuel than a conventional take-off, leaving less fuel for the mission.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-11-18T21:53:05.840" LastActivityDate="2016-11-18T21:53:05.840" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="13767" PostTypeId="2" ParentId="13762" CreationDate="2015-04-01T20:37:33.247" Score="21" Body="&lt;p&gt;With current technology the L/D might go up to 70 or 75, and going higher would require an almost impractically large wing span. Gliders need to fly in tight circles to use updrafts, and the larger the wingspan becomes, the bigger the speed difference between inner and outer wing will be. Also, landing such a wide wing without dropping a wingtip will be very hard. Smaller wings with a high aspect ratio will have a low chord length, leading to smaller &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number&lt;/a&gt;s, which translates into a steep increase of friction drag if the aspect ratio is increased without increasing wing area. Therefore, only adding wing span will help, and this runs into a soft wall beyond the 30 m of designs like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eta_(glider)&quot; rel=&quot;noreferrer&quot;&gt;Eta&lt;/a&gt;. In addition, the current &lt;a href=&quot;http://en.wikipedia.org/wiki/Glider_competition_classes&quot; rel=&quot;noreferrer&quot;&gt;mass limit of 850 kg&lt;/a&gt; will make bigger aircraft unattractive for competition pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://lesgpr.free.fr/construire/concordia/ConcImagine_WV_e.pdf&quot; rel=&quot;noreferrer&quot;&gt;Concordia (pdf!)&lt;/a&gt; is claimed to have an L/D approaching 75, but I have learned over the years to see theoretical predictions as invariably optimistic, and realistic performance, with bugs on the wing and all, will never quite measure up to the hoped-for ideal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.nasa.gov/centers/dryden/pdf/88792main_Laminar.pdf&quot; rel=&quot;noreferrer&quot;&gt;Werner Pfenniger proposed to use boundary layer laminarisation by suction (pdf!)&lt;/a&gt; to reduce friction drag and proposed glider designs with L/D ratios in excess of 100. Turbines at the wingtips would drive the suction pumps, so these would still be unpowered aircraft. But so far nobody has dared to turn his visions into reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While laminarisation avoids the increase in friction drag of a turbulent boundary layer, a moving wall would eliminate viscous losses altogether. Now the friction generation is between the moving wall (this could be a taut foil running between two cylinders at the forward and aft end of the wing) and the fixed structure. With current materials there is no hope of reducing drag this way, but who knows what tricks will be possible in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A glide ratio of 100 or more looks rather unlikely in the next 50 years.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-02T17:43:35.273" LastActivityDate="2015-04-02T17:43:35.273" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13768" PostTypeId="2" ParentId="13764" CreationDate="2015-04-01T20:58:11.167" Score="11" Body="&lt;p&gt;Yes, they can accelerate straight up (even at max weight in some cases), but to accelerate straight up from 0 airspeed requires some kind of control to keep the aircraft stable.  All of the aircraft's normal control surfaces only work with air flowing across them, so if you stood it up and pushed the throttles forward it would simply tip itself over.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why VTOL aircraft always have more than one point creating thrust, they use thrust to stabilize the aircraft as it rises.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other consideration (as Peter mentioned) is that it's less efficient to climb this way, meaning less fuel for the mission, lower takeoff weight, or some other tradeoff.  &lt;/p&gt;&#xA;" OwnerUserId="7752" LastActivityDate="2015-04-01T20:58:11.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13770" PostTypeId="1" CreationDate="2015-04-01T22:41:48.390" Score="27" ViewCount="4602" Body="&lt;p&gt;In the Air Crash Investigation episode &quot;Kid In The Cockpit,&quot; which details the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot;&gt;Aeroflot Flight 593&lt;/a&gt;, the video shows the plane had a yoke not a sidestick&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was under the impression all Airbus models, even the earlier ones, used a sidestick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anybody clarify this for me? &lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="22726" LastEditDate="2019-01-01T01:35:33.797" LastActivityDate="2019-01-01T01:35:33.797" Title="Was the Airbus A300/A310 ever supplied with a yoke and not a sidestick?" Tags="&lt;cockpit&gt;&lt;airbus&gt;&lt;sidestick&gt;&lt;airbus-a310&gt;&lt;airbus-a300&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13771" PostTypeId="2" ParentId="13770" CreationDate="2015-04-01T23:15:26.750" Score="32" Body="&lt;p&gt;The sidestick was a design that came about along with the new &lt;a href=&quot;http://www.airbus.com/innovation/proven-concepts/in-design/fly-by-wire/&quot;&gt;fly-by-wire technology of the A320&lt;/a&gt; in the &lt;a href=&quot;http://www.airbus.com/company/history/the-narrative/fly-by-wire-1980-1987/&quot;&gt;late 1980's&lt;/a&gt;. The physical leverage of a yoke was no longer needed for flight control cables. The older designs of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus&quot;&gt;A300 and A310 series planes&lt;/a&gt; from the 70's and 80's have &lt;a href=&quot;https://www.google.com/search?q=AIRBUS%20a310%20cockpit&quot;&gt;conventional yoke flight controls&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would not be surprised to see inaccuracies in TV reenactments, but the yoke did happen to be important in that particular case.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-02T01:08:19.710" LastActivityDate="2015-04-02T01:08:19.710" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13772" PostTypeId="2" ParentId="5095" CreationDate="2015-04-02T00:04:08.463" Score="7" Body="&lt;p&gt;The Cockpit Area Microphone (CAM) can be in a variety of places due to different cockpit designs.  Generally, it is supposed to be installed in the best position for recording voice communications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a Boeing 777, it is on the overhead panel next to the passenger seat belt sign switch:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zOI1Y.jpg&quot; alt=&quot;B777 overhead&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: &lt;a href=&quot;http://www.airliners.net/photo/Emirates/Boeing-777-21H-ER/0130318/M/&quot; rel=&quot;noreferrer&quot;&gt;Craig Murray / Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an Airbus A318/A319/A320/A321, it is in between the windscreen and the overhead panel, just below the exterior lights switches:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zqjFz.jpg&quot; alt=&quot;A320 overhead&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: &lt;a href=&quot;http://www.airliners.net/photo/Croatia-Airlines/Airbus-A320-214/0590473/M/&quot; rel=&quot;noreferrer&quot;&gt;Niksa Radicevic / Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-04-02T00:04:08.463" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13773" PostTypeId="5" CreationDate="2015-04-02T01:32:23.023" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:38:37.377" LastActivityDate="2015-04-02T01:38:37.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13774" PostTypeId="4" CreationDate="2015-04-02T01:32:23.023" Score="0" Body="Aeroflot 593 was a Moscow–Hong Kong passenger service flown with an Airbus A310-300, that crashed into a mountain range in Russia on 23 March 1994. The pilot's children had unknowingly disabled the autopilot's control of the ailerons while seated at the controls. The aircraft had then rolled into a steep bank and near-vertical dive from which the pilots were unable to regain control." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:32:23.023" LastActivityDate="2015-04-02T01:32:23.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13775" PostTypeId="5" CreationDate="2015-04-02T01:36:30.570" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pan_Am_Flight_103&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:36:30.570" LastActivityDate="2015-04-02T01:36:30.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13776" PostTypeId="4" CreationDate="2015-04-02T01:36:30.570" Score="0" Body="Pan Am Flight 103 (involved in the Lockerbie bombing) was a regularly scheduled transatlantic flight from Frankfurt-Detroit via London and New York that was destroyed by a terrorist bomb on Wednesday, 21 December 1988. Large sections of the aircraft crashed into Lockerbie, Scotland." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:36:30.570" LastActivityDate="2015-04-02T01:36:30.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13777" PostTypeId="5" CreationDate="2015-04-02T01:44:03.177" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/LOT_Polish_Airlines_Flight_16&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:44:03.177" LastActivityDate="2015-04-02T01:44:03.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13778" PostTypeId="4" CreationDate="2015-04-02T01:44:03.177" Score="0" Body="LOT Polish Airlines Flight 16 was a passenger flight from Newark-Warsaw on 1 November 2011, flown by a Boeing 767-300ER, in which its landing gear failed to extend. A hydraulic leak occurred shortly after takeoff, which resulted in a loss of all the hydraulic fluid that powered the primary landing gear system." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:44:03.177" LastActivityDate="2015-04-02T01:44:03.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13779" PostTypeId="5" CreationDate="2015-04-02T01:45:35.593" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:45:35.593" LastActivityDate="2015-04-02T01:45:35.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13780" PostTypeId="4" CreationDate="2015-04-02T01:45:35.593" Score="0" Body="TAM Airlines Flight 3054 was a scheduled passenger flight between Porto Alegre-São Paulo. On Tuesday, July 17, 2007, the Airbus A320-233 airliner overran the runway at São Paulo and crashed into a nearby TAM Express warehouse adjacent to a Shell filling station. It remains the deadliest aviation accident involving an A320." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:45:35.593" LastActivityDate="2015-04-02T01:45:35.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13781" PostTypeId="5" CreationDate="2015-04-02T01:55:14.450" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:55:14.450" LastActivityDate="2015-04-02T01:55:14.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13782" PostTypeId="4" CreationDate="2015-04-02T01:55:14.450" Score="0" Body="Japan Airlines 123 was a passenger flight from Haneda-Osaka on a Boeing 747SR. On August 12 1985 it crashed into a mountain near Tokyo. It had a tailstrike 7 years earlier which damaged its rear pressure bulkhead. The repair didn't conform to the approved process, using 2 separate doubler plates, instead of 1 continuous plate. The bulkhead gave way &amp; an explosive decompression ruptured the lines of all 4 hydraulic systems &amp; ejected the vertical stabilizer." OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-02T01:55:14.450" LastActivityDate="2015-04-02T01:55:14.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13783" PostTypeId="1" AcceptedAnswerId="13784" CreationDate="2015-04-02T02:25:36.547" Score="9" ViewCount="6680" Body="&lt;p&gt;It seems that FAA requirements for any particular aircraft revolve heavily around the aircraft's type certificate.  Civil aircraft are broken up into several categories based on weight or passenger count, etc.  But I did not see a section on military operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do military aircraft undergo type certification?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="19" LastEditDate="2015-04-02T09:26:22.960" LastActivityDate="2015-04-19T17:41:18.993" Title="How are military aircraft type certificated?" Tags="&lt;faa-regulations&gt;&lt;military&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13784" PostTypeId="2" ParentId="13783" CreationDate="2015-04-02T04:13:52.227" Score="13" Body="&lt;p&gt;In the US, the military is not required to obtain FAA type certificates for their aircraft; the FAA is not the authority certifying a military-registered plane's airworthiness. They have the &lt;em&gt;option&lt;/em&gt; of accepting an FAA type certificate (which they tend to do on aircraft based on civilian ones), but they run their own certification agencies for airworthiness, which are all that matters if the plane is in the military registration system. Here's an &lt;a href=&quot;http://static.e-publishing.af.mil/production/1/saf_aq/publication/afpd62-6/afpd62-6.pdf&quot;&gt;Air Force policy&lt;/a&gt; on the matter, here's a &lt;a href=&quot;http://www.lockheedmartin.com/content/dam/lockheed/data/aero/documents/global-sustainment/product-support/2010HOC-Presentations/Wed_1400_FAA-Military_Commercial_Deriv_Aircraft-Melvin_Taylor.pdf&quot;&gt;Lockheed powerpoint&lt;/a&gt; on the option to use FAA certification on commercial derivatives.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-02T04:13:52.227" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13785" PostTypeId="1" AcceptedAnswerId="13786" CreationDate="2015-04-02T05:21:55.577" Score="7" ViewCount="432" Body="&lt;p&gt;If a helicopter is reported by the NTSB as Destroyed in their Accident report, and as they make no disposal recommendation in their reports, can the aircraft be legally rebuilt by an authorized and approved FAA and Bell Repair facility and flown again?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Follow up: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft in question, after using Bell referenced repairs, carried out by a Bell Licensed Repair facility, in a Bell Certified Jig, now has its Certificate of Airworthiness and is again Supported by Bell and has a handsome price tag.&lt;/p&gt;&#xA;" OwnerUserId="7976" LastEditorUserId="3386" LastEditDate="2015-05-23T13:08:40.837" LastActivityDate="2017-01-06T22:59:53.810" Title="Can a &quot;Destroyed&quot; Helicopter be repaired and flown?" Tags="&lt;accidents&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13786" PostTypeId="2" ParentId="13785" CreationDate="2015-04-02T06:15:40.587" Score="10" Body="&lt;p&gt;The NTSB defines &lt;em&gt;Destroyed&lt;/em&gt; as &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Damaged due to impact, fire, or in-flight failures to an extent not economically repairable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another common definition is: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The estimated or likely cost of repairs would have exceeded 50&#xA;  percent of the new value of the airplane had it still been in&#xA;  production at the time of the accident.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This fact that the costs of repairing are &lt;em&gt;estimated&lt;/em&gt; to be exceed the economical value of the aircraft does technically not prevent the aircraft to be repaired and made flyable again. It can be recertified on the original airworthiness certificate. See &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1027070&quot;&gt;FAA order 8130.2H&lt;/a&gt;. &#xA;Special attention needs to be given to the identification plate (serial numbers etc.) of the aircraft; the original plates of the aircraft have to be installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not expect any support from Bell as on their &lt;a href=&quot;http://www.bellhelicopter.com/en_US/SupportServices/FlightSafety/AircraftHistory/AircraftHistory.html&quot;&gt;website&lt;/a&gt; they state:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are some aircraft that have been destroyed in an accident or&#xA;  retired from service that are no longer considered to be genuine Bell&#xA;  Helicopter Aircraft. These aircraft will not be supported by Bell&#xA;  Helicopter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This makes resurrected Bell helicopters very difficult to sell in the future.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="679" LastEditDate="2015-04-02T06:39:42.497" LastActivityDate="2015-04-02T06:39:42.497" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13787" PostTypeId="2" ParentId="13738" CreationDate="2015-04-02T08:18:45.467" Score="12" Body="&lt;p&gt;According to WallStreetJournal &lt;a href=&quot;http://www.wsj.com/articles/SB10001424127887323968304578247681812331570&quot;&gt;article&lt;/a&gt;, Tom Horton stated in an interview that :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A 777 paint job can cost  \$100,000 to  \$200,000, depending on the number of colors involved, and a smaller Airbus A320 can cost $50,000 or more.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="679" LastEditorUserId="679" LastEditDate="2015-04-02T23:31:20.503" LastActivityDate="2015-04-02T23:31:20.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13788" PostTypeId="2" ParentId="13783" CreationDate="2015-04-02T12:36:00.180" Score="2" Body="&lt;p&gt;The military has their own set of certification standards for aircraft. They draw their authority from their task to provide national defense. &lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-04-02T12:36:00.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13791" PostTypeId="5" CreationDate="2015-04-02T17:24:52.670" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-04-02T17:24:52.670" LastActivityDate="2015-04-02T17:24:52.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13792" PostTypeId="4" CreationDate="2015-04-02T17:24:52.670" Score="0" Body="Automatic Dependent Surveillance - Contract (ADS-C) is a surveillance technology used mainly over remote areas such as oceanic airspace." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-04-02T17:24:52.670" LastActivityDate="2015-04-02T17:24:52.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13793" PostTypeId="1" AcceptedAnswerId="13800" CreationDate="2015-04-02T17:29:50.017" Score="20" ViewCount="4530" Body="&lt;p&gt;It seems to me that race cars (like &lt;a href=&quot;http://en.wikipedia.org/wiki/Formula_One&quot;&gt;Formula 1&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/NASCAR&quot;&gt;NASCAR&lt;/a&gt;) and small GA aircraft (like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Cessna_172&quot;&gt;Cessna 172&lt;/a&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot;&gt;Piper Cherokee&lt;/a&gt;) travel at generally the same speeds, roughly between 70 and 200 mph. Yet, if an accident happens, you appear to be more likely to die in a small plane than a race car.**&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I figure this may have to do with some of the safety features of race cars versus the safety features of GA aircraft. The main features being the &lt;a href=&quot;http://www.outmotoring.com/images/P/SCR_harness_md.jpg&quot;&gt;racing harness&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Roll_cage&quot;&gt;roll cage&lt;/a&gt;.  (And also, as Freeman pointed out in a comment, the &lt;a href=&quot;http://en.wikipedia.org/wiki/HANS_device&quot;&gt;HANS device&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Racing_helmet&quot;&gt;helmet&lt;/a&gt; help quite a lot as well, especially in frontal impacts.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know roll cages weight about 80lbs and that they aren't cheap, and I know a safety harness can be difficult to put on and people might not like using them, and I know a HANS device can be cumbersome, as also a helmet can be. But forget all of that for a moment. I'm not asking about why we don't use them from an economic/utility perspective.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I really want to know is if putting these in a small airplane would be of any benefit to begin with. It's true that they are massively helpful in racing vehicles, but I wonder if the forces racing vehicles face during a crash are markedly different than what you would find in your typical GA crash (e.g., perhaps aircraft accidents happen at less predictable angles, or involve more torsion, etc.). And if perhaps those differences in forces make the use of a roll cage and a safety harness kind of pointless in a small plane because they can't actually help in that kind of accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, would all of these racing safety devices actually make a GA crash more survivable, or does the nature of GA accidents make their use less effective than they are in a race car?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;** &lt;em&gt;Try as I might, I couldn't find hard stats on &quot;deaths per accident&quot; in either area.  So this is mostly an impression I've gained from reading a lot of NTSB reports and watching a lot of racing. The fact may be debatable, but shouldn't detract from the main question.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-04-02T19:03:30.100" LastActivityDate="2018-03-20T18:50:10.080" Title="Would a roll cage plus a safety harness make a small GA aircraft accident more survivable?" Tags="&lt;safety&gt;&lt;aircraft-design&gt;" AnswerCount="4" CommentCount="12" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13794" PostTypeId="5" CreationDate="2015-04-02T17:32:23.573" Score="0" Body="" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-04-02T17:32:23.573" LastActivityDate="2015-04-02T17:32:23.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13795" PostTypeId="4" CreationDate="2015-04-02T17:32:23.573" Score="0" Body="The Ground Proximity Warning System (GPWS) warns flight crew if the aircraft is in immediate danger of flying into terrain or an obstacle. The first generation of these systems was developed in the 1970s to reduce the number of controlled flight into terrain (CFIT) accidents. At the end of the 20th century, a newer generation of systems became available, called Enhanced Ground Proximity Warning System (EGPWS)." OwnerUserId="19" LastEditorUserId="22726" LastEditDate="2019-10-03T08:21:45.870" LastActivityDate="2019-10-03T08:21:45.870" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13796" PostTypeId="5" CreationDate="2015-04-02T17:47:44.853" Score="0" Body="&lt;p&gt;Malaysia is a country in Southeast Asia.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The Civil Aviation Authority of Malaysia is called the &lt;a href=&quot;http://www.dca.gov.my/mainpage.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Directorate of Civil Aviation&lt;/a&gt; &lt;a href=&quot;/questions/tagged/dca-malaysia&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dca-malaysia&amp;#39;&quot; rel=&quot;tag&quot;&gt;dca-malaysia&lt;/a&gt; / &lt;a href=&quot;/questions/tagged/dca-malaysia-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dca-malaysia-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;dca-malaysia-regulations&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aeronautical Information Publication: &lt;a href=&quot;http://aip.dca.gov.my/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIP&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Airports in East Malaysia (Borneo) have ICAO codes starting with &lt;strong&gt;WB&lt;/strong&gt;.&#xA;For airports in Peninsular Malaysia, ICAO codes start with &lt;strong&gt;WM&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two major airports of Malaysia are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;WMKK - Kuala Lumpur International Airport &lt;a href=&quot;http://en.wikipedia.org/wiki/Kuala_Lumpur_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;(wikipedia)&lt;/a&gt;  &lt;/li&gt;&#xA;&lt;li&gt;WBKK - Kota Kinabalu International Airport &lt;a href=&quot;http://en.wikipedia.org/wiki/Kota_Kinabalu_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;(wikipedia)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The national airline of Malaysia is Malaysia Airlines. Other airlines are AirAsia and AirAsia X.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="22726" LastEditDate="2018-06-15T22:05:31.593" LastActivityDate="2018-06-15T22:05:31.593" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13797" PostTypeId="4" CreationDate="2015-04-02T17:47:44.853" Score="0" Body="For questions regarding aviation and its regulations in Malaysia." OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2018-06-15T20:53:36.210" LastActivityDate="2018-06-15T20:53:36.210" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13798" PostTypeId="2" ParentId="13793" CreationDate="2015-04-02T19:02:55.303" Score="7" Body="&lt;p&gt;The short answer is no. But if you are curious as to what it would look like check &lt;a href=&quot;http://blog.caranddriver.com/spirit-of-lemons-how-a-1956-cessna-airplane-became-a-road-racing-lemons-car-w-build-photosvideo/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Racing accidents are generally different than GA accidents. Although race cars often slam straight into things they tend to have what is called an Impact attenuater out front. Since F1 cars are mid engine the nose is often left empty and can house impact absorbent materials. Planes are limited in this by having a propeller out front (unless its a small twin). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Roll cages in cars help to protect against (lets not be silly here) but rolling, something that F1 cars can do if they say, corner to hard and fly off the track. The thing to remember here as well is that a car only really moves in the X-Y plane. It is easier to predict how a car will and can hit something by limiting the range of motion. A plane can hit the ground at almost any attitude in any configuration in the X-Y-Z plane. This means the cage would have to be much more through. Keep in mind as well that a roll cage in a car just protects the driver, not the whole car. While you could have a roll cage just around the area that people are sitting you still have a weight issue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets ignore the weight for a minute and think about when a roll cage could help a plane. If you were coming in for an engine out approach and something happened at a low altitude causing the plane to hit the ground and roll you may see some benefit. If you botch (and lets hope you never do) a landing you may see some benefit if the plane rolls over or hits something. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it wont help, any kind of nose dive situation or sever ground impact its not going to get you much but it will get you something. In this case you want something that will absorb the shock not stay intact and transfer it to you.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has been brought up that auto racers also wear things like wrist restraints, neck braces, helmets and harnesses. Having worn these things before I can confidently say that it is very difficult to move around in them but when driving a race car you only really need to see straight in front of you and a bit off to each side. Flying VFR would be tough if you were that strapped in and had to move your head around to look out the window. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While we are on the topic (although a bit unrelated) a fire retardant suit like the ones worn by F1 drivers could provide some protection in certain aviation style accidents as they do provide a very real, very measurable amount of protection. The best example I can think of is a serious cabin fire that somehow exists in such a way you still have control over the plane. In this case the suit may buy you enough time to get the plane on the ground and egress safely.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real issue also comes down to cost. Are you willing to sacrifice 80-150LBS of useful load to tote around a cage that is not really going to make anything that much safer. Carbon composite shows a lot of promise in this field by simply making stronger and lighter frames but for what its worth these things are still not cheap. And lets be honest there are lots of things, like full air frame chutes, individual parachutes etc, that would make flying safer, but at some point you have to assume some risk to successfully partake in the activity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some research I found out that Mooney implements a roll cage of sorts into its design see &lt;a href=&quot;http://www.mooneyland.com/safety-how-mooney-protects/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; for some notes on it. &lt;a href=&quot;https://www.youtube.com/watch?t=100&amp;amp;v=HRHGbx6cb4c&quot; rel=&quot;nofollow&quot;&gt;This video&lt;/a&gt; claims that the newer Mooney has a &quot;NASCAR designed roll cage to keep the occupants safe. &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=39412&quot; rel=&quot;nofollow&quot;&gt;This Thread&lt;/a&gt; brings up some interesting points on roll cages and reenforced structures vs the Cirrus full fame chute and may be worth a read. Although Mooney does have a roll cage of sorts my previous points still hold true in respect to ADDING a roll cage. The Mooney cage is part of the airframe its self and is there from day one of design.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-10T15:20:32.050" LastActivityDate="2015-05-10T15:20:32.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13799" PostTypeId="2" ParentId="13793" CreationDate="2015-04-02T19:21:21.813" Score="0" Body="&lt;p&gt;A HANS device seems like it would be a non-starter because pilots need to be able to move their head during normal flight. Unlike race car drivers, pilots are concerned with more than just what is directly in front of them or to their left. Also, they need to be able to grab stuff out of the back, adjust radios on the other side of the cockpit, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases, a GA aircraft 'crash' will be less violent (i.e. lower instantaneous acceleration) than a car slamming into another car or a wall. While this isn't always the case, in most cases a crash is either just sliding off the side of a runway or landing on something that isn't meant to be landed on, not usually impacting something head-on. Additionally, aircraft generally don't roll. They might flip forwards over the nose, but rolling is rather difficult, given the length of the wings. The wings would usually have to break off or the roll would have to happen while airborne and then crash inverted in order for the aircraft to 'roll.' As such, the added weight of the roll cage would generally not be worthwhile, especially since it would be a very significant portion of the overall weight in a light aircraft, which matters a lot more than the weight of a car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as more complicated restraints, they would have to be very quickly and very reliably removable. Fires are a big issue in light GA crashes, so the ability to get out ASAP is very important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as helmets are concerned, while these might make sense in aircraft that are operating in conditions where a crash is more likely (racing, aerobatics, etc.,) it seems like their annoyance in normal use would outweigh the benefit in the still rather unlikely scenario of a crash. Even from a pure safety standpoint, annoying/restricting/distracting the pilot seems likely to cause more fatal accidents than it would prevent. In general, I'd say the reasons are pretty similar to why we don't wear helmets when driving down the highway, even though my car will be moving faster on the drive home from the airport than my plane will be moving on touchdown. The cost/benefit ratio is just too high for it to be worthwhile.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-04-02T19:21:21.813" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13800" PostTypeId="2" ParentId="13793" CreationDate="2015-04-02T20:07:17.540" Score="13" Body="&lt;p&gt;Short answer: Yes, a better harness would help in some cases, but will achieve little all by itself. A roll cage might help in a few cases, too, but would be much less effective per pound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your observation is correct: Race car drivers enjoy a lot more protection than GA pilots. This is a rather recent development; 30 years ago the chances of surviving a crash were equally low for both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two factors which stand out in a GA crash:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Peak accelerations which will lead to internal lesions like the rupture of the coronary blood vessels, and&lt;/li&gt;&#xA;&lt;li&gt;Physical injury by sharp objects entering the occupant's space, including flailing limbs being hurt by sharp objects in the cabin.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Both factors were also killers for race car drivers, and they were defused with improved design methods. A safety cage is not just a frame around the driver: Any structural failure must occur in such a way that the structure fails away from the driver. In addition, the whole car body is designed to crumple at roughly the same force over its length in order to use the available crumpling zone as well as possible. This allows to decelerate the safety cage at a constant rate, so that peak loads can be avoided. A third factor is a much better &lt;a href=&quot;http://www.ogracing.com/blog/2013/02/6-things-you-need-to-consider-before-buying-harnesses/&quot; rel=&quot;noreferrer&quot;&gt;restraint system&lt;/a&gt;, of which the HANS device is only one aspect. Using five-point harnesses would already help to avoid &quot;submarining&quot;, a process where the pelvis slides under the lower restraint, causing the harness to press against the intestines. The image below shows the regular pelvis location and body contours as a dashed outline and the displaced pelvis and spine as a solid line. The displaced body is the shaded area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PNrAy.png&quot; alt=&quot;Pelvis location change during submarining&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of this was considered at the time when today's GA aircraft were developed and the regulations were set up. At that time the prevailing opinion was that nothing could be done in a crash, so all efforts focussed on avoiding crashes in the first place. Adding only parts of the whole protection packet will be of little help - only their combination can effectively protect the race car driver. Even the 5-point harness needs an adequate seat and properly located mounting points to be effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US army has collected all research up to the early Eighties in a five volume work called the &lt;a href=&quot;http://www.aero.polimi.it/~anghi/bacheca_sp/materiale_didattico/ACSDG_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;Army Aircraft Crash Survival Guide (pdf!)&lt;/a&gt;. It's intention is to improve the crash survivability for helicopter occupants and Army aviators, and much can be transferred to General Aviation. If you look for hard stats, you will find at least lots of citations there. I remember in particular a study from the Fifties where statistics showed that &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_J-3_Cub&quot; rel=&quot;noreferrer&quot;&gt;J-3&lt;/a&gt; pilots would mostly be killed in a crash, while the rear occupant would show only minor injuries. In the study, Pipers filled with test dummies were put on rails and crashed into an earth wall. Funny stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uqzcb.jpg&quot; alt=&quot;Piper J-3 or O-59&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A J-3 in Army livery. Then it was called O-59 or L-4.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T08:53:37.570" LastActivityDate="2015-05-10T08:53:37.570" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13801" PostTypeId="1" AcceptedAnswerId="13802" CreationDate="2015-04-02T20:24:04.633" Score="7" ViewCount="4775" Body="&lt;p&gt;Where can I find the &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_level&quot; rel=&quot;nofollow noreferrer&quot;&gt;transition altitude&lt;/a&gt; in different countries or regions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hoping to cover as many places as possible. Links to the applicable regulations would be nice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also:&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/13204/1696&quot;&gt;What is the difference between &amp;quot;flight level&amp;quot; and &amp;quot;altitude&amp;quot;?&lt;/a&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/37/1696&quot;&gt;Where can I find regulations in different countries for flight level rules based on direction of flight?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Instead of request a list, now the question asks for how to find in general. A few examples should still be given though.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-08T17:38:08.937" Title="Where can I find the transition altitude in different countries/regions?" Tags="&lt;airspace&gt;&lt;altitude&gt;&lt;regulations&gt;&lt;flight-level&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ClosedDate="2020-07-08T17:04:19.130" ContentLicense="CC BY-SA 3.0" />
  <row Id="13802" PostTypeId="2" ParentId="13801" CreationDate="2015-04-02T20:24:04.633" Score="8" Body="&lt;h1&gt;Asia&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hong Kong: &lt;a href=&quot;http://www.fly-sea.com/charts/VHHH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;9,000 feet&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Africa&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;South Africa: fixed and to be at least 1000 ft above the highest ground within 25nm radius of an airfield (&lt;a href=&quot;http://www.caa.co.za/Aeronautical%20Information%20Circulars/20.2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIC 20.2&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Europe&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Belgium: 4,500 feet (&lt;a href=&quot;http://www.belgocontrol.be/website/eaip/eAIP_Main/html/index-en-GB.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIP Part 2,, ENR 1.7.2&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Netherlands: 3,000 feet (IFR) / 3,500 feet (VFR) (&lt;a href=&quot;http://www.ais-netherlands.nl/aim/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIP Part 2, ENR 1.7.1.1&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Oceania&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Australia: 10,000 feet MSL (&lt;a href=&quot;https://www.airservicesaustralia.com/aip/current/aip/enroute.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIP ENR 1.7 (2.1.1))  &lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;New Zealand: 13,000 feet AMSL (&lt;a href=&quot;https://www.caa.govt.nz/rules/Rule_Consolidations/Part_091_Consolidation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAA CAR 91.425&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;North America&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Canada: 18,000 feet (&lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-602.34&quot; rel=&quot;nofollow noreferrer&quot;&gt;SOR/96-433 602.34&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;United States: 18,000 feet MSL (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.2.91_1121&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §91.121&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;South America&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Argentina: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;li&gt;Brasil: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;li&gt;Chile: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;li&gt;Colombia: 18,000 ft (&lt;a href=&quot;http://www.icao.int/SAM/Documents/2013-SAMIG12/SAMIG12_NE23.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;SAM/IG/12-NE/23&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Ecuador: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;li&gt;Paraguay: 3000 ft (&lt;a href=&quot;http://www.icao.int/SAM/Documents/2013-SAMIG12/SAMIG12_NE23.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;SAM/IG/12-NE/23&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Perú: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;li&gt;Uruguay: 3000 ft (&lt;a href=&quot;http://www.icao.int/SAM/Documents/2013-SAMIG12/SAMIG12_NE23.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;SAM/IG/12-NE/23&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Venezuela: Depends on terminal airspace&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-08T17:38:08.937" CommentCount="0" CommunityOwnedDate="2015-04-02T20:24:04.633" ContentLicense="CC BY-SA 3.0" />
  <row Id="13803" PostTypeId="2" ParentId="13764" CreationDate="2015-04-02T21:53:44.583" Score="5" Body="&lt;p&gt;The closest the US ever got to it is the &lt;a href=&quot;https://www.youtube.com/watch?v=oImq1glnOds&quot; rel=&quot;noreferrer&quot;&gt;ZEL program for the F-100&lt;/a&gt; Super Sabre.&lt;br/&gt;&#xA;Basically, put the F-100 on a cruise missile launch rail, strap one hell of a big rocket booster to its arse, and run for cover.&lt;br/&gt;&#xA;Used to have a 90 minute VHS tape about the project, they got so far as to design underground launch ramps with nuclear blast proof doors to launch the fighters after Soviet bombers. Never went operational though, by the time it had progressed to where it could work in practice the Nike SAM system was mature enough the ZEL program was no longer needed.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-04-02T21:53:44.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13805" PostTypeId="1" AcceptedAnswerId="13806" CreationDate="2015-04-03T08:37:21.043" Score="17" ViewCount="6502" Body="&lt;p&gt;On airliners, passenger seatbelts are simple lap belts. However, flight crews seem to have at least shoulder straps, and often five-point harnesses. Why do flight crew have more restraints?&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-10-08T16:47:46.897" Title="Why do airline pilots have shoulder harnesses?" Tags="&lt;safety&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13806" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T08:43:16.763" Score="31" Body="&lt;ul&gt;&#xA;&lt;li&gt;pilots need to be able to do work during turbulence.&lt;/li&gt;&#xA;&lt;li&gt;passengers don't really like to be fully restrained.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="3386" LastEditDate="2015-04-03T10:02:48.150" LastActivityDate="2015-04-03T10:02:48.150" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="13807" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T10:32:49.547" Score="9" Body="&lt;p&gt;There have been some &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot;&gt;&quot;unusual attitude&quot; instances&lt;/a&gt; where the crew have recovered the aircraft but would have possibly been thrown from their seats or unable to reach the controls through excessive G if not fully restrained.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-04-03T11:15:01.813" LastActivityDate="2015-04-03T11:15:01.813" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13808" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T11:46:26.700" Score="2" Body="&lt;p&gt;For passengers, while flying I feel fully restrained around the hips by a lap belt fully tightened- it would be more comfortable to have the belt load spread out. A full car seat belt compared to a lap belt allows you full motion.   Its more likely the cost and difficult of having more anchor points on all seats especially when they spread them across the plane- a place to join the belt to the seat at higher point. They might also have to design the seat to handle its load being more spread out. Let alone having to work out if having such &quot;improved&quot; belts actually helps survivability with the greater risk of being unable to unclip.     &lt;/p&gt;&#xA;" OwnerUserId="2671" LastActivityDate="2015-04-03T11:46:26.700" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13809" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T12:26:25.183" Score="18" Body="&lt;p&gt;They're required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.verifavia.com/bases/ressource_pdf/299/icao-annex-6-part-i.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Annex 6, Part 1&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;6.2.2 An aeroplane shall be equipped with:&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  c) 3) a safety harness for each flight crew seat.  The safety harness shall incorporate a device which will automatically restrain the occupant's torso in the event of rapid deceleration&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also confirm's &lt;a href=&quot;https://aviation.stackexchange.com/questions/13805/why-do-airline-pilots-have-shoulder-harnesses#comment30842_13806&quot;&gt;Ben's comment&lt;/a&gt; that they are also meant to restrain an incapacitated pilot:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Recommendation.&amp;ndash;&lt;/strong&gt; &lt;em&gt;The safety harness for each pilot seat should incorporate a device to prevent a suddenly incapacitated pilot from interfering with the flight controls.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-03T12:26:25.183" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13810" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T12:36:22.430" Score="8" Body="&lt;p&gt;In airliners, shoulder harnesses are not installed for &lt;strong&gt;passengers&lt;/strong&gt; because:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;it is not not mandated by law&lt;/li&gt;&#xA;&lt;li&gt;it is too much for average passengers to deal with&lt;/li&gt;&#xA;&lt;li&gt;it requires money to install&lt;/li&gt;&#xA;&lt;li&gt;it is superfluous in a crash when compared to the same safety from a lap belt&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight crew&lt;/strong&gt; is required to use the shoulder harness (when installed) as it is the law (&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.105&quot;&gt;14 CFR 91.105&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) During takeoff and landing, and while en route, each required&#xA;  flight crewmember shall—  &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) Be at the crewmember station unless the absence is necessary to&#xA;    perform duties in connection with the operation of the aircraft or in&#xA;    connection with physiological needs; and&lt;br&gt;&#xA;    (2) Keep the safety belt fastened while at the crewmember station.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;(b) Each required &lt;strong&gt;flight crewmember&lt;/strong&gt; of a U.S.-registered civil&#xA;  aircraft shall, &lt;strong&gt;during takeoff and landing, keep his or her shoulder&#xA;  harness fastened while at his or her assigned duty station&lt;/strong&gt;. This&#xA;  paragraph does not apply if—  &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) The seat at the crewmember's station is not equipped with a shoulder harness; or&lt;br&gt;&#xA;    (2) The crewmember would be unable to perform required duties with the shoulder harness fastened.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-04-03T12:36:22.430" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13811" PostTypeId="2" ParentId="13793" CreationDate="2015-04-03T12:38:26.563" Score="9" Body="&lt;p&gt;&lt;em&gt;Disclaimer: I am the VP at HANS Performance Products, makers of the HANS device. I know a little about cockpit safety but am new to the field of GA safety.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drivers survive horrific crashes in auto racing because they are extremely well contained. A 360-degree surround seat (often called a full containment or halo seat), a multi-point harness, fireproof suit, gloves and shoes plus a helmet and head restraint are used to contain the driver. This often results in drivers surviving 100g impacts (not the 10g mentioned above). For example Ritchie Hearn hit the concrete wall at Indy at 129g and suffered only a broken foot. He was wearing a HANS device. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although many race cars can exceed 250mph it is the rate of deceleration that causes injury. In this I think GA and auto racing accidents are similar. In fact EMT crews often talk about high speed racing accidents as airplane accidents on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no single magic bullet to cockpit safety. Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=691_FgzuKaI&quot;&gt;short video&lt;/a&gt; on the topic that may be useful to GA pilots and engineers.&lt;/p&gt;&#xA;" OwnerUserId="7989" LastEditorUserId="65" LastEditDate="2015-04-03T13:06:31.190" LastActivityDate="2015-04-03T13:06:31.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13813" PostTypeId="1" AcceptedAnswerId="13835" CreationDate="2015-04-03T13:10:53.737" Score="13" ViewCount="38741" Body="&lt;p&gt;I'm wondering how the airports charge an airline for using a gate or a parking spot (if they use buses). Does the airline have to pay per time or per &quot;event&quot; or do the larger airlines have fixed gates for which they pay a yearly rent?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could you elaborate on what systems there are and when they are used? How much are the costs?&lt;/p&gt;&#xA;" OwnerUserId="7988" LastEditorUserId="1696" LastEditDate="2015-04-05T16:24:59.507" LastActivityDate="2015-04-08T06:24:09.153" Title="How do airports charge airlines for using their gates?" Tags="&lt;airport&gt;&lt;cost&gt;&lt;airlines&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13814" PostTypeId="2" ParentId="13738" CreationDate="2015-04-03T13:15:52.023" Score="5" Body="&lt;p&gt;A &lt;a href=&quot;https://en-maktoob.news.yahoo.com/blogs/the-971-report/what-does-it-take-to-paint-a-boeing-777--stunning-timelapse-shows-emirates-plane-getting-make-over-070307604.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;news article&lt;/a&gt; that linked that video said it took Emirates Airlines 6550 hours to repaint 21 aircraft, an average of 312 hours each.  They run a round-the-clock operation, with 26-30 people working at any given time, so that translates into roughly 8500-9000 man hours to complete each plane.  If the &lt;a href=&quot;http://www1.salary.com/Aircraft-Painter-I-hourly-wages.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;average entry level salary&lt;/a&gt; there is similar to the US at \$18/hr, that's upwards of $175,000 just in labor.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if a paint job &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;weighs 555 lbs on a 747&lt;/a&gt; (and that's &lt;em&gt;after it dries&lt;/em&gt; &amp;ndash; think of the lost moisture), and your spray efficiency is around 50%, we're talking closer to &lt;em&gt;2000&lt;/em&gt; lbs of wet paint to purchase to get the job done.  At around 9.0 lbs/gallon, that's about 220 gallons of paint.  Sherwin Williams sells paint for around \$50/gal, so that's another \$11,000 for the paint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then facility costs for electricity and cooling, but I don't have to get into that, as we're already nearing the upper estimate of the per-aircraft cost vasin1987 cited in &lt;a href=&quot;https://aviation.stackexchange.com/a/13787/6919&quot;&gt;his answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-04-03T13:15:52.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13815" PostTypeId="1" CreationDate="2015-04-03T15:56:39.387" Score="8" ViewCount="2498" Body="&lt;p&gt;I have a sport pilot license and fly my own SLSA (Special Light Sport Aircraft). I have all the required logbook hours signed off by my CFI for the PPL and 120 hours as PIC plus 80 dual student hours. Once I pass the PPL written test and obtain a 3rd class medical, would I be required to take a full oral test and check ride to obtain a PPL?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;SLSA: Special Light Sport Aircraft&lt;/li&gt;&#xA;&lt;li&gt;CFI:  Certificated Flight Instructor&lt;/li&gt;&#xA;&lt;li&gt;PIC:  Pilot In Command&lt;/li&gt;&#xA;&lt;li&gt;PPL:  Private Pilot License&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;EDIT: Thanks for responding. I do have 3 night flying hours + 3 hours under the hood. I did all the required private pilot flying and ground school hours before deciding to go the light sport route. I'm thinking about about getting the private pilot license if and when the 3rd class medical is eliminated as a requirement. So, my question is - what would I be tested on for the private pilot checkride? Or would a checkride even be required?&lt;/p&gt;&#xA;" OwnerUserId="7993" LastEditorUserId="14661" LastEditDate="2019-04-18T04:21:16.787" LastActivityDate="2019-04-18T04:21:16.787" Title="Sport pilot upgrade to private pilot" Tags="&lt;faa-regulations&gt;&lt;ppl&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ClosedDate="2015-04-03T23:13:18.337" ContentLicense="CC BY-SA 4.0" />
  <row Id="13816" PostTypeId="1" AcceptedAnswerId="13817" CreationDate="2015-04-03T16:32:02.737" Score="10" ViewCount="3901" Body="&lt;p&gt;When the pilot (PIC) of a large jet is cleared for pushback and start, how does he signal the tug to start towing the aircraft, and where to go to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot has to monitor the ground frequency the whole time, so is there a second radio for talking to the tug crew? Or perhaps a wired link between the aircraft and the tug?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does he just tell them to &quot;take us to start point alpha&quot; or whatever, or does he have to give more detailed instructions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the tug crew listening in to the instructions from the tower?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft has to stop unexpectedly (because of an instruction from the tower, or because the pilot has a safety concern), how is this coordinated safely?&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="65" LastEditDate="2015-04-03T19:46:15.217" LastActivityDate="2015-04-27T14:39:41.093" Title="How are pushbacks coordinated between the pilot and the tug?" Tags="&lt;airliner&gt;&lt;radio-communications&gt;&lt;pushback&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13817" PostTypeId="2" ParentId="13816" CreationDate="2015-04-03T16:42:57.157" Score="12" Body="&lt;p&gt;Generally speaking&lt;sup&gt;1&lt;/sup&gt;, when an aircraft is allowed/ready to leave (deliberately not using the word &lt;em&gt;depart&lt;/em&gt;) the gate, things proceed in the following fashion:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The pilots are in contact with &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control#Ground_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ground Control&lt;/a&gt;, and when the aircraft is ready to leave, Ground approves that they can leave the gate.&lt;/li&gt;&#xA;&lt;li&gt;The pilots asks &lt;a href=&quot;http://en.wikipedia.org/wiki/Groundcrew&quot; rel=&quot;nofollow noreferrer&quot;&gt;groundcrew&lt;/a&gt; that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pushback&quot; rel=&quot;nofollow noreferrer&quot;&gt;pushback&lt;/a&gt; can start.&lt;/li&gt;&#xA;&lt;li&gt;Pilots are in contact with a designated personal from groundcrew (see picture below).&lt;/li&gt;&#xA;&lt;li&gt;Pushback tractor/tug will start moving the aircraft away from gates, onto the place where aircraft will be ready to move on its own.&lt;/li&gt;&#xA;&lt;li&gt;During the pushback, aircraft's engines are started&lt;sup&gt;2&lt;/sup&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Pilots inform tug driver/designated person from groundcrew which direction the aircraft needs to be facing at the conclusion of pushback.&lt;/li&gt;&#xA;&lt;li&gt;When aircraft is ready to roll towards its assigned taxi instructions, &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_marshalling&quot; rel=&quot;nofollow noreferrer&quot;&gt;marshaller&lt;/a&gt; signals the pilots that aircraft is in the requested position and pushback tug is about to be detached.&lt;/li&gt;&#xA;&lt;li&gt;After the tug is disconnected, the designated groundcrew personal communicating with pilots, informs the pilots and disconnects his headset. The marshaller signals (after moving away from the aircraft) the pilots that the aircraft is ready to proceed on its taxi route.&lt;/li&gt;&#xA;&lt;li&gt;Pilots confirm and acknowledge this last signal, and aircraft starts to taxi.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/21125&quot; rel=&quot;nofollow noreferrer&quot;&gt;read that different airports have different procedures&lt;/a&gt; for the above mentioned activities. Although, I have always seen that a person from groundcrew attaches a headset near the nose gear of the aircraft (picture below) to communicate with the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gxzW7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gxzW7.jpg&quot; alt=&quot;Groundcrew Headset&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://cdn.c.photoshelter.com/img-get/I00007teqbmbmPy8/s/650/520/aviation-corbis06-21-04-2001.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;br&gt;&#xA;Please see the cable connecting the headset with the aircraft, near the nose gear. You cannot follow the entire cable though.&lt;/em&gt;&#xA;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: This is what a typical scenario looks like. Although, there can be great variations.&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;: Engines are not started near the gate as there is groundcrew servicing the airplane and to avoid damages to close-by structures.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-04-24T18:27:29.163" LastActivityDate="2015-04-24T18:27:29.163" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13818" PostTypeId="2" ParentId="13815" CreationDate="2015-04-03T17:12:42.480" Score="5" Body="&lt;p&gt;I believe PPL also requires some night flying time (at least the 141 school I am at does). I believe Sport Pilot License is not valid at night so you may have to gain some night landings and hours to go for the check ride as well. However I do see that you have all the hours signed off so I will assume this includes night hours.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But AFAIK you will need to pass the written, oral and check ride to get the PPL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per your updates &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; is what you will be checked on for your check ride. Its a bit dated but &lt;a href=&quot;https://www.youtube.com/watch?v=kr483zBbQKw&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; video has some nice coverage on what you may get on your oral exam. If you have the Jeppesen study materials you should have some good lists of what you will find. I did find this in the FAR &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§61.103   Eligibility requirements: General.&#xA;  To be eligible for a private pilot certificate, a person must:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Be at least 17 years of age for a rating in other than a glider or balloon.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Be at least 16 years of age for a rating in a glider or balloon.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Be able to read, speak, write, and understand the English language. If the applicant is unable to meet one of these requirements due to medical reasons, then the Administrator may place such operating limitations on that applicant's pilot certificate as are necessary for the safe operation of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Receive a logbook endorsement from an authorized instructor who:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Conducted the training or reviewed the person's home study on the aeronautical knowledge areas listed in §61.105(b) of this part that apply to the aircraft rating sought; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Certified that the person is prepared for the required knowledge test.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Pass the required knowledge test on the aeronautical knowledge areas listed in §61.105(b) of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Receive flight training and a logbook endorsement from an authorized instructor who:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Conducted the training in the areas of operation listed in §61.107(b) of this part that apply to the aircraft rating sought; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Certified that the person is prepared for the required practical test.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) Meet the aeronautical experience requirements of this part that apply to the aircraft rating sought before applying for the practical test.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(h) Pass a practical test on the areas of operation listed in §61.107(b) of this part that apply to the aircraft rating sought.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Comply with the appropriate sections of this part that apply to the aircraft category and class rating sought.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(j) Hold a U.S. student pilot certificate, sport pilot certificate, or recreational pilot certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In regards to section H you have to pass the practical for the PPL specifically so it would seem you will be retested. Although part J would allude to the fact that your SPC comes in here it seems that it just counts in place of a student pilot certificate. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-04-03T18:56:42.437" LastActivityDate="2015-04-03T18:56:42.437" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13820" PostTypeId="2" ParentId="13815" CreationDate="2015-04-03T18:50:59.613" Score="1" Body="&lt;p&gt;Unfortunately, there is no reduction in the examination requirements to go from a Sport Pilot to Private Pilot. You will need to take the written, oral, and practical tests as if you just held a Student Pilot certificate. The &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Practical Test Standards&lt;/a&gt; for Private Pilot include a table which can reduce the maneuvers you need to demonstrate on the practical test based on certificates already held - but they all require a Private Pilot or higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of your solo/PIC hours as a Sport Pilot count for the requirements for the Private Pilot certificate, as do any dual time with a CFI or CFII. Any dual time with someone who only has a CFIS (Sport Pilot instructor) certificate does not qualify as experience for the Private Pilot certificate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full requirements for you to take the Private Pilot practical test are available in &lt;a href=&quot;https://aviation.stackexchange.com/q/1199/65&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-04-03T19:09:18.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13821" PostTypeId="2" ParentId="13805" CreationDate="2015-04-03T19:02:57.317" Score="5" Body="&lt;p&gt;If the plane is in turbulence, and the passenger is jostled about, injured, or even knocked unconscious, well, sucks for him, but he will recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more extreme the situation, the more important it is that the pilot be conscious, uninjured, and stable.&lt;/p&gt;&#xA;" OwnerUserId="1973" LastActivityDate="2015-04-03T19:02:57.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13822" PostTypeId="2" ParentId="4995" CreationDate="2015-04-03T21:15:17.967" Score="3" Body="&lt;p&gt;When a Boeing Jetliner reaches the end of the programmed flight plan track with the autopilot engaged in Lateral NAV and the pilot does not intervene, (which is usually at a terminal aid (VOR or NDB) at the destination airport); the autopilot will remain engaged, however the tracking mode will default to the last flown track heading into the last navigation aid and the heading window will open showing the numerals.  Pilot intervention is then required to change the heading or tracking of the aircraft as desired or instructed by ATC.&lt;/p&gt;&#xA;" OwnerUserId="7997" LastActivityDate="2015-04-03T21:15:17.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13823" PostTypeId="2" ParentId="13805" CreationDate="2015-04-04T00:13:04.207" Score="15" Body="&lt;p&gt;I recall early in my glider training when I was about 17 before Id gone solo.  My instructor used to keep his shoulder straps loose so I started doing the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On my 1st &lt;em&gt;actual&lt;/em&gt; cable snap on the winch tow I whacked the stick forward and the glider went into -ve g.  It was an open-cockpit glider with no canopy and I was half hanging out and only just managed to reach and get fingertips of one hand onto the joystick to pull myself back into the plane.  I stabilised the glider, pulled my straps tight, but then found out my instructor behind me was not responding.  I landed safely and then found out he was unconscious.  He had bashed his head on the wing above him and passed out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;em&gt;always&lt;/em&gt; had my straps fastened properly after that incident.&lt;/p&gt;&#xA;" OwnerUserId="7998" LastEditorUserId="3386" LastEditDate="2015-10-08T16:47:46.897" LastActivityDate="2015-10-08T16:47:46.897" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13824" PostTypeId="1" AcceptedAnswerId="13828" CreationDate="2015-04-04T04:36:42.897" Score="37" ViewCount="10641" Body="&lt;p&gt;While there was debate over why &lt;a href=&quot;https://aviation.stackexchange.com/questions/2354/why-are-planes-generally-painted-white&quot;&gt;airplanes  are painted white&lt;/a&gt; and a question about &lt;a href=&quot;https://aviation.stackexchange.com/questions/13738/how-much-does-it-cost-to-give-an-airliner-a-fresh-coat-of-paint&quot;&gt;how much a new paint job costed&lt;/a&gt;, what hasn't been asked is why airplanes are painted at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember one airline company sent out a press release in the 1980s or 1990s that keeping its planes unpainted (i.e, a nice silver) saved several hundred gallons of paint as well as considerable cost savings because the plane was also lighter and used less fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there are considerable positives to keeping planes unpainted, why do airline companies bother painting them? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is prompted by a recent flight I had on an US Air airplane that had just been repainted in the American Airlines livery. The captain joked that the paint was still so new that we shouldn't try touching it. Both companies are famous for always being in severe debt -- so saving every penny should have meant going for the 'naked' look.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related:&lt;/strong&gt; A &lt;a href=&quot;http://www.quora.com/How-much-fuel-would-we-save-globally-if-all-airlines-stripped-the-paint-off-their-planes-and-brought-it-down-to-a-sheen&quot; rel=&quot;noreferrer&quot;&gt;quora question&lt;/a&gt; on how much money would be saved if airlines stopped painting their liveries and a &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html&quot; rel=&quot;noreferrer&quot;&gt;Boeing white paper on painted vs unpainted&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="15311" LastEditDate="2017-12-10T15:42:10.463" LastActivityDate="2018-06-04T12:34:16.370" Title="Why are commercial airplanes painted at all?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;economics&gt;&lt;livery&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13825" PostTypeId="2" ParentId="13824" CreationDate="2015-04-04T05:29:06.450" Score="27" Body="&lt;p&gt;Quite apart from the paint preventing corrosion, which puts the lie to the idea that AA flies unpainted aircraft (they don't, they use a clear paint on metallic parts and metallic paint on non-metallic parts), there's the economic factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those aircraft are flying billboards for their owners. They are a major part of brand recognition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's why they're repainted or at the very least have stickers applied when rented/leased out to other operators.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="6919" LastEditDate="2015-04-04T13:25:43.227" LastActivityDate="2015-04-04T13:25:43.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13826" PostTypeId="2" ParentId="13824" CreationDate="2015-04-04T09:06:03.880" Score="7" Body="&lt;p&gt;Painted aircraft can be kept looking clean with a relatively quick wash, while unpainted metal requires comparatively more effort and time (thus, money) to be kept shiny. The fuel savings may simply be more than offset by the maintenance fees. &lt;/p&gt;&#xA;" OwnerUserId="7999" LastEditorUserId="1467" LastEditDate="2015-04-04T09:41:29.360" LastActivityDate="2015-04-04T09:41:29.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13827" PostTypeId="2" ParentId="12931" CreationDate="2015-04-04T09:44:39.680" Score="10" Body="&lt;p&gt;Based on ICAO doc9157 Aerodrome Design Manuel Part1 Runway, the minimum distance between centre lines of 2 parallel( or near-parallel ) runways is&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Visual Meteorological Conditions (VMC) operation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;210m for category 3( runway length=1200m-1800m ) and category 4(&#xA;  runway length&gt;1800m )&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;150m for category 2( runway length=800m-1200m )&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;120m for category 1( runway length&amp;lt;800m )&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And for Instrument flight Condition (IMC) operation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1035m for independent parallel approaches ( radar separation minima&#xA;  between aircraft and adjacent centre line is not prescribed)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;915m for independent parallel approaches ( radar separation minima&#xA;  between aircraft and adjacent centre line is prescribed)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;760m for independent parallel departures or Segregated parallel&#xA;  operations (one exclusive for departure and another for landing)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PS: It can be reduced by 30m for each 150m arrival runways is&#xA;  staggered toward arrival aircraft down to 300m between centre line of&#xA;  two runways; and vice versa (but no maximum)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When two runways are closer than the regulations above, only one can be &quot;operated&quot; at the same time (eg: LGW). Even though only one of the parallel runway would be operated at the same time, the separation of the runway have to follow the &quot;Runway strip rule&quot;, which is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;75m each side from the centre lines for category 3/4&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;40m each side for category 2&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;30m each side for category 1&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore minimum distance of two parallel runways is the sum of the strips,ie: minimum distance of two parallel 4E/F runways is 75+75=150m from their centre lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above is global standard which represents the minimum requirement of runway , other aviation authorities such as FAA in US may have stricter standard.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-06-04T11:43:57.910" LastActivityDate="2015-06-04T11:43:57.910" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13828" PostTypeId="2" ParentId="13824" CreationDate="2015-04-04T09:54:08.967" Score="40" Body="&lt;p&gt;I remembered hearing that paint actually reduces the drag of the plane. Searching a bit I found &lt;a href=&quot;http://flightshield.com/docs/Boeing%20Report.pdf&quot;&gt;this Boeing document &lt;/a&gt; describing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the painting reduces the fuel costs, instead of increasing them. Another interesting thing is, that planes are regularly repainted to keep the drag low. Of course there is the &lt;em&gt;billboard&lt;/em&gt; effect too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In response to numerous questions raised by &#xA;  Boeing customers regarding the efficacy of &#xA;  surface coatings to reduce drag, Boeing has&#xA;  investigated some possible airflow physics &#xA;  explanations. Possible explanations postulated by Boeing aerodynamicists include:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Increased regions of laminar flow due to reduced surface roughness.&lt;/li&gt;&#xA;  &lt;li&gt;Reduction in surface roughness resulting in lower skin friction drag, when flow is turbulent.&lt;/li&gt;&#xA;  &lt;li&gt;Reduction in dirt and/or insect adhesion resulting in reduced roughness and hence reduced skin friction drag.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8002" LastEditorUserId="1467" LastEditDate="2015-04-04T10:19:03.740" LastActivityDate="2015-04-04T10:19:03.740" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13829" PostTypeId="2" ParentId="13824" CreationDate="2015-04-04T17:54:27.493" Score="7" Body="&lt;p&gt;I think more importantly it also helps the ground crews and the air traffic control tower responsible for ground traffic.  When looking at a line up of planes from a distance, you can eliminate a majority of planes right away because they are either the wrong airline or wrong type.  Now you only have to compare the tail numbers of a couple aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several years back I was getting a tour from a friend of orlando's control tower, and as you can imagine it is a pretty busy place especially up top where they are relying on their eyes to organize the traffic on the ground.  When tracking an aircraft that's taxing, they have two pieces of information, tail number and airline.  So if you have a lineup that goes AA, United, UPS, United, Frontier for instance, you don't even have to break out the binoculars to know what their tail numbers are except to maybe to differentiate between the two united flights.  Speeds up the process and also cuts down on careless error.&lt;/p&gt;&#xA;" OwnerUserId="8007" LastEditorUserId="8007" LastEditDate="2015-04-04T17:59:28.677" LastActivityDate="2015-04-04T17:59:28.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13830" PostTypeId="1" CreationDate="2015-04-04T19:35:28.593" Score="10" ViewCount="427" Body="&lt;p&gt;A Vertical Speed Indicator indicates rate of altitude change. Traditional VSIs use a &lt;a href=&quot;https://aviation.stackexchange.com/a/9250/136&quot;&gt;calibrated leak&lt;/a&gt; to measure the rate of pressure change, and therefore the rate of altitude change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, pressure does not change uniformly per altitude: in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8168/where-is-the-official-definition-of-pressure-altitude&quot;&gt;standard atmosphere&lt;/a&gt;, air pressure at 0 MSL is 29.921 inHg, and at 1000 MSL is 28.856 inHg: a 1.065 inHg difference. But 10,000 MSL is 20.577 inHg and 11,000 is 19.791 inHg: a .789 inHg difference. A calculation suggests that a VSI calibrated for sea level and climbing at 1,000 ft/min would indicate 739 ft/min at 10,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airspeed indicator has a knob to calculate true airspeed based on altitude and temperature, but the VSI has no pilot-accessible controls. Glass panel instruments would presumably handle this automatically, but is there any correction for altitude in a steam-gauge VSI?&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-30T10:43:33.660" Title="Do steam-gauge VSIs compensate for altitude?" Tags="&lt;flight-instruments&gt;&lt;vertical-speed&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13834" PostTypeId="2" ParentId="318" CreationDate="2015-04-05T00:45:02.600" Score="-1" Body="&lt;p&gt;You need to be at or above 4000 to ID CLAUD if using the cross radial (197) from the vor that is out of view , that is why a MOCA is there.&lt;/p&gt;&#xA;" OwnerUserId="8010" LastActivityDate="2015-04-05T00:45:02.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13835" PostTypeId="2" ParentId="13813" CreationDate="2015-04-05T01:11:38.470" Score="12" Body="&lt;p&gt;Gates are usually not charged to airlines separately. Gate fee is usually part of the landing fee package. Landing fees are an important part of the airport revenue, with passenger fees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport pricing is subject to recommendations from ICAO, IATA, and other organizations, as regard scope of costs to be taken into consideration, and non-discrimination of airlines. Pricing is determined by the organization managing the airport and/or State or local administration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Single till vs dual till&lt;/strong&gt;: Distinguishes between aeronautical and non-aeronautical (commercial) charges. Airport schedule pricing may use single or dual till. See: &lt;a href=&quot;https://www.iata.org/policy/Documents/single-till.pdf&quot; rel=&quot;noreferrer&quot;&gt;Single till&lt;/a&gt; - IATA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/publications/Documents/9082_9ed_en.pdf&quot; rel=&quot;noreferrer&quot;&gt;ICAO Policies on Charges for Airports and Air Navigation Service&lt;/a&gt;. ICAO guidelines tries to maintain some principles for airport business across all countries:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Landing charges&lt;/strong&gt;: Should be based on the aircraft weight formula. The maximum certificated take-off weight as indicated in the certificate of airworthiness (or other prescribed document) should be used, while considering local restrictions that may affect aircraft maximum take-off weight. Allowance should be made for the use of a fixed charge per aircraft or a combination of a fixed charge with a weight-related element, in certain circumstances, such as at congested airports and during peak periods.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Parking and hangar charges&lt;/strong&gt;: For the determination of charges associated with use of parking, hangar and long-term storage of aircraft, maximum permissible take-off weight and/or aircraft dimensions (area occupied) and length of stay should be used so far as possible as the basis.&lt;br&gt;&lt;br&gt;Any period of free parking time for aircraft immediately following landing should be determined locally by considering aircraft scheduling, space availability and other pertinent factors. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Other charges&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-- Passenger service charges&lt;br&gt;&#xA;-- Security charges&lt;br&gt;&#xA;-- Noise-related charges&lt;br&gt;&#xA;-- Emissions-related aircraft charges  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Albeit a bit old, &lt;em&gt;The Airport Business&lt;/em&gt; by Rigas Doganis has a chapter on &lt;a href=&quot;https://books.google.fr/books?id=2ryHAgAAQBAJ&amp;amp;lpg=PR12&amp;amp;dq=%22The%20Airport%20Business%22%20chapter%204&amp;amp;hl=fr&amp;amp;pg=PA63#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical charges and pricing policies&lt;/a&gt; which discusses this topic in depth. Extracts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Landing fees&lt;/strong&gt;: Charged per aircraft, usually based on MTOW (maximum takeoff weight). On most airports covers ATC, runways, taxiways, parking at stand or apron for a certain time (e.g. 2 hours), use of gates / fingers / terminal for disembarking (use for departure may be paying), take-off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Surcharges&lt;/strong&gt; or &lt;strong&gt;rebates&lt;/strong&gt; in addition of landing fees: For noise, peak-hour operations,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Parking and hangar&lt;/strong&gt;: Beyond the free-parking period covered by the landing fees. Usually based on weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Passenger charges&lt;/strong&gt;: per departing passenger, sometime per arriving passenger too.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is easy to find pricing for airports online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.adelaideairport.com.au/assets/pdfs/fees-and-charges/ScheduleOfChargesAdelaide17Feb2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;Adelaïde&lt;/a&gt; airport (2015)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rates are different for domestic and international flights.&lt;/li&gt;&#xA;&lt;li&gt;Charges per passenger for landing and passenger facility. &lt;/li&gt;&#xA;&lt;li&gt;For domestic flights, additional landing charges per ton of MTOW.&lt;/li&gt;&#xA;&lt;li&gt;Charges for diversion.&lt;/li&gt;&#xA;&lt;li&gt;Parking charges beyond 2 hours, paid per arrangement with airport.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;New York &lt;a href=&quot;http://www.panynj.gov/airports/pdf/scheduleofcharges-lga.pdf&quot; rel=&quot;noreferrer&quot;&gt;LaGuardia&lt;/a&gt; (2015)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Charge for aircraft landing, per thousand pounds of MGLW (maximum gross landing weight).&lt;/li&gt;&#xA;&lt;li&gt;Additional charge for day landing or takeoff (not for schedule airlines).&lt;/li&gt;&#xA;&lt;li&gt;Charge for using public passenger ramp and apron area (in some cases, when congestion).&lt;/li&gt;&#xA;&lt;li&gt;Charge for parking and storage, per 8-hour slot, based on MGTOW (maximum gross takeoff weight). Agreement possible for operators of aircrafts.&lt;/li&gt;&#xA;&lt;li&gt;No charge for air terminal use.&lt;/li&gt;&#xA;&lt;li&gt;Charge for each passenger departing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.lawa.org/uploadedFiles/AirOps/pdf/rules%20/11%20Section%2008%20-%20Airport%20Operating%20Permits%20and%20Fees%20-%202013%2007.pdf&quot; rel=&quot;noreferrer&quot;&gt;Los Angeles Intl&lt;/a&gt; (2013)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landing fee, based on MGLW, different between permitted and non-permitted air carriers.&lt;/li&gt;&#xA;&lt;li&gt;No charge for remote gates bussing service.&lt;/li&gt;&#xA;&lt;li&gt;Charge for using ramp, apron and remote area, (in some cases, when congestion).&lt;/li&gt;&#xA;&lt;li&gt;Charge for parking, per 1000 lbs of MGLW, per day, after 3 hours.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="1696" LastEditDate="2015-04-05T16:23:48.043" LastActivityDate="2015-04-05T16:23:48.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13836" PostTypeId="2" ParentId="1539" CreationDate="2015-04-05T11:29:52.567" Score="1" Body="&lt;p&gt;Just stumbled across this directory, hosted by VATSIM. Doesn't appear to be entirely up to date but does provide a link for charts for Prague, among many others. (Includes links to content that may be behind a paywall though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.vatsim.net/charts/&quot; rel=&quot;nofollow&quot;&gt;http://www.vatsim.net/charts/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-04-05T11:29:52.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13837" PostTypeId="1" AcceptedAnswerId="13839" CreationDate="2015-04-05T11:42:58.177" Score="25" ViewCount="8584" Body="&lt;p&gt;I am reading the book &lt;em&gt;Mechanics and Thermodynamics of Propulsion&lt;/em&gt;, by &lt;em&gt;Hill&lt;/em&gt; and &lt;em&gt;Peterson&lt;/em&gt;. I found out this image while reading the chapter 5, &quot;Thermodynamics of Aircraft Engines&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KqhDo.png&quot; alt=&quot;Turbofan and Turboprop&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would there be a gearbox in the turboprop but not on the turbofan? Was this just a result of a simple, quick, representative sketch? Or did authors forget to add the gearbox to the turbofan?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later in the text, it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The gearbox is necessary so that both propeller and core engine can operate at optimum rotational speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There it says &quot;optimum rotational speed&quot;. Is that the speed of the compressor? The speed of the fan? Or maybe an intermediate, flight-airspeed-dependant speed? How does the gearbox know which is that &quot;optimum speed&quot;?&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="770" LastEditDate="2015-04-09T03:32:43.837" LastActivityDate="2018-02-18T04:54:22.973" Title="Given the same engine, why install a gearbox on a turboprop but not on a turbofan?" Tags="&lt;turboprop&gt;&lt;geared-turbofan&gt;" AnswerCount="7" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13838" PostTypeId="2" ParentId="13837" CreationDate="2015-04-05T11:57:03.267" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;There it says &quot;optimum rotational speed&quot;. Is that the speed of the compressor? The speed of the fan?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Both. Each has its own optimal speed (that is not the same) and the gear allows them to work at that speed. Defining what &quot;optimal&quot; is, is part of the engineers job; usually &quot;optimal&quot; is what gives the maximum efficiency, but depending on the design restrictions a different speed might be selected.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does the gearbox know which is that &quot;optimum speed&quot;?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It does not &quot;know&quot;, it is simply built so that everything will run smoothly. In &lt;a href=&quot;https://aviation.stackexchange.com/questions/8081&quot;&gt;this question&lt;/a&gt; it has been explained why there is not manual transmission on aircrafts: the gear ratio is fixed. This also answer your question, it is fixed and the gear ratio is selected during the design phase.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why would there be a gearbox in the turboprop but not on the turbofan?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because the propeller runs at much slower speeds. The fan can be connected directly to the low pressure turbine, while a propeller would rotate too fast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propeller rotates much slower than the fan because it operates on a different principle: the fan accelerates a smaller amount of air by a larger $\Delta V$ (it has to act also as a firts stage for the compressor) while the propeller accelerates an higher amount of air by a smaller $\Delta V$. This difference is noticeable also in other three aspects: the fan is ducted and has many more blades (remember, it's a first stage for the compressor), while the propeller has a few blades and is not ducted; additionally, as Peter mentions in his answer, the propeller generally has a larger diameter than a fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please also have a look at &lt;a href=&quot;https://aviation.stackexchange.com/questions/4966&quot;&gt;this question&lt;/a&gt; where the differences between turbofan and turboprop are discussed&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-04-05T13:59:39.193" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13839" PostTypeId="2" ParentId="13837" CreationDate="2015-04-05T12:13:43.757" Score="28" Body="&lt;p&gt;The bigger the diameter, the lower the optimum speed. Generally, fan and propeller blades should run at a high dynamic pressure, but still at subsonic speeds to avoid the higher losses involved with supersonic flow. Since the tip will be the part with the highest speed, and propellers have bigger diameters than fans, propellers run at lower speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high pressure compressor and turbines of an airliner engine will run at above ten thousand RPM, while the propeller wants to run at about 1800 to 2200 RPM. The propellers on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/22229/why-is-the-tu-95-so-efficient-despite-having-propellers-that-spin-faster-than-th/22231?s=1%7C0.1301#22231&quot;&gt;Tu-95 even run at only 750 RPM&lt;/a&gt;. Both the fan and the propeller are powered by separate low pressure turbines which also have an optimum speed, and the faster the turbine runs, the more torque it will produce for a given size. For that reason, the low pressure turbine and the shaft of a big airliner engine run at between 2500 and 4000 RPM, and the turbine of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot; rel=&quot;noreferrer&quot;&gt;PT-6&lt;/a&gt;, a classical turboprop engine, at 30.000 RPM. Since power is torque times RPM, a faster running shaft will be lighter than one running at low speed, so the speed is only reduced directly at the propeller mount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fan's optimum speed is between that of the compressor and the propeller and would &lt;a href=&quot;https://aviation.stackexchange.com/questions/11586/what-is-a-high-bypass-geared-turbofan-and-why-is-it-so-much-more-efficient&quot;&gt;ideally also need a gearbox&lt;/a&gt;, but here the transmitted power is so high that a compact gearbox will be hard to design. Even if it runs at 98% efficiency, it will produce waste heat &lt;a href=&quot;https://aviation.stackexchange.com/questions/11969/what-prevent-jet-engines-design-with-bigger-by-pass-ratio/11972#11972&quot;&gt;in the order of several hundred kilowatts&lt;/a&gt; in case of a big airliner engine. Some small engines with just a single turbine use gearboxes already (e.g. the &lt;a href=&quot;http://en.wikipedia.org/wiki/Honeywell_LF_507&quot; rel=&quot;noreferrer&quot;&gt;Lycoming ALF507&lt;/a&gt;), and now the next generation of &lt;a href=&quot;https://aviation.stackexchange.com/questions/12753/what-are-the-limitations-in-adoptions-of-gtf-geared-turbofan-technology/12974#12974&quot;&gt;efficient fan engines&lt;/a&gt; are also introducing gearboxes. But so far, most engine designs have preferred to run the fan faster than what would be ideal. Note that the tip speed of a modern, ungeared fan is &lt;a href=&quot;https://aviation.stackexchange.com/questions/22316/why-do-turbofan-blade-tips-exceed-the-speed-of-sound-while-prop-tips-should-not/22317?s=2%7C0.1408#22317&quot;&gt;already well above Mach 1&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their bigger diameter makes &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;propellers more efficient&lt;/a&gt;. The more air mass is involved in thrust creation, the higher the propulsive efficiency will be. Fans need to be smaller precisely because they will run with the speed of the low pressure turbine, and to convert the available power into thrust, &lt;a href=&quot;https://aviation.stackexchange.com/questions/13545/why-dont-aeroplanes-use-propellers-with-more-blades-like-the-intake-on-a-fanjet/13549#13549&quot;&gt;they need a much higher solidity ratio&lt;/a&gt;, which translates into a higher wetted surface, which increases friction losses.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-05-01T04:55:00.400" LastActivityDate="2017-05-01T04:55:00.400" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13840" PostTypeId="2" ParentId="13600" CreationDate="2015-04-05T12:28:36.523" Score="2" Body="&lt;p&gt;It depends on who shoot the plane.&lt;/p&gt;&#xA;&lt;p&gt;With the spirit of Juche idea, Kim Il Sung (Supreme leader of North Korea) can shoot planes with handgun easily. There is a selection from North Korea textbook:)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;General Kim Il Sung left the cave and saw several of the bombers from US imperialists bombarding the base continuously. The heroic People's Army soldiers kept shooting the American aircrafts but useless.&lt;/p&gt;&#xA;&lt;p&gt;Frowning angrily , the General saw an American aircraft tried to bomb again, he raised his handgun and aimed at the enemy aircraft. When the enemy is aligned the people army again and came down, the General shot. Shortly, a mass of huge fireball erupted in the sky with falling wreckage. The remaining US pilots were scared and escaped. Soldiers cheered toward the General Kim Il Sung:&lt;/p&gt;&#xA;&lt;p&gt;Long live the Great Leader Kim Il Sung!&lt;/p&gt;&#xA;&lt;p&gt;Long live the Great General Kim Il Sung!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;But for other people, it seems impossible. Major damage of shooting comes from explosive within warhead. In WWII, most of the fighters installed 20mm machine gun or even larger, however, there is many case which the heavily shooted fighters have successfully landed on runways and aircraft carriers. Handgun even cannot kill a man for some times, how can it shot down a plane by most people?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-06T05:50:53.693" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13841" PostTypeId="2" ParentId="13749" CreationDate="2015-04-05T13:48:40.043" Score="1" Body="&lt;p&gt;Though Harbin Aircraft Manufacturing Corporation (HAMC) said Y-11 is a fully indigenous design, no other direct evidences prove/reject what it says. However, some indirect evidence shall be considered:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Except Y11, the only brand new design from HAMC is Z15 in 2008(Coperation with Airbus), other designs from HAMC are either authorised production or modification from existed model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Y11 was designed in the period of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Cultural_Revolution&quot; rel=&quot;nofollow&quot;&gt;Cultural Revolution&lt;/a&gt;. There is insufficient engineers and research process is often influenced by political movement. However, Y-11 started first flight 8 months after the requirement is issued.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the evidences i dont think it is a fully indigenous Chinese design, as they dont have experience for fully indigenous design in such a short period.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-04-05T13:48:40.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13843" PostTypeId="1" CreationDate="2015-04-05T14:01:05.653" Score="6" ViewCount="1576" Body="&lt;p&gt;The single biggest cost for many airlines is fuel. Given this, I'm sure they work hard to reduce the cost they pay per gallon of fuel as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does that translate to the way fuel is bought at major airports? I know there's a fuel truck that comes and fills up the planes. Does each airport partner with one company to provide fuel? Are the multiple providers on each airport? Does the airport itself sell fuel? Is fuel lumped into the landing fee?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2015-04-07T00:57:23.803" Title="What does the airport fuel market look like?" Tags="&lt;airline-operations&gt;&lt;airport&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13844" PostTypeId="1" CreationDate="2015-04-05T15:27:35.180" Score="3" ViewCount="872" Body="&lt;p&gt;Both New York and London have insufficient air traffic capacity. One option for London is to build a &lt;a href=&quot;https://en.wikipedia.org/wiki/Thames_Estuary_Airport&quot; rel=&quot;nofollow&quot;&gt;new mega airport&lt;/a&gt; to replace &lt;a href=&quot;https://en.wikipedia.org/wiki/London_Heathrow_Airport&quot; rel=&quot;nofollow&quot;&gt;LHR&lt;/a&gt;. However, this option is not discussed much in NY. Would it be feasible to build a new mega airport to serve New York?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="6886" LastEditDate="2015-07-06T05:02:38.347" LastActivityDate="2015-07-06T05:02:38.347" Title="Could New York build a new mega airport?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-04-05T19:23:00.327" ContentLicense="CC BY-SA 3.0" />
  <row Id="13845" PostTypeId="2" ParentId="13844" CreationDate="2015-04-05T15:43:05.987" Score="2" Body="&lt;p&gt;Due to regulations, 2 runways in an airport are not answering less demand in an airport than 2 times one runway. So there is a loss of efficiency when 2 runways are built, that depends strongly of their relative orientation and their separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means, that creating such a big airport will start requesting a massive size of land to have enough separation between airplanes and/or inefficient use of runways. You can easily finalize having flights of 1 hours and trips around that airport of 30 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this limitation, and the potential cost of the land (usually very expensive close to the city) eliminates economies of scale, making more economically efficient to create 2 airports than creating a single big one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally is a balance between several economical factors, but you can see that London, Paris, Berlin and New York are currently served by several airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking that information to answer your questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Actually London is not thinking in creating a big airport, they are trying to expand &lt;a href=&quot;http://en.wikipedia.org/wiki/Expansion_of_London_Heathrow_Airport&quot; rel=&quot;nofollow&quot;&gt;LHR&lt;/a&gt; or &lt;a href=&quot;http://www.gatwickobviously.com/&quot; rel=&quot;nofollow&quot;&gt;Gatwick&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Concerning NY, creating a big airport to replace La Guardia, Newark and JFK will be a very big airport very far from the city center and very likely to not be efficient.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-04-05T15:43:05.987" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13846" PostTypeId="2" ParentId="9160" CreationDate="2015-04-05T15:57:07.607" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The captain starts pulling back and to the right to turn right. First officer initiates a left diving turn. What happens?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It depends.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Linked controls&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On some aircraft, the main controls are linked, often mechanically. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the strongest pilot, or the one with most stamina, wins. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may potentially be a period of alternating sudden strong deflections of the control surfaces as the two pilots fight for control.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Independent controls&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On some aircraft, the main controls are not linked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will usually be visual, audible and sometimes tactile indications to both pilots of a conflict, if both pilots are making inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either pilot can typically press a priority switch to gain control and cause the other pilot's inputs to be ignored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may potentially be a period where conflicting pilots are alternately pressing their priority switches. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Column vs sidestick&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Either the traditional control-columns or modern sidesticks can, in principle be designed for either linked or independent operation. It happens that there are two major makers who have historically taken different choices for both these aspects but it is possible to have linked-sidesticks or independent-columns.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Airbus&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The operation of the priority switch is shown in a &lt;a href=&quot;https://www.youtube.com/watch?v=SKNJ-ABAPuY&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A slightly longer &lt;a href=&quot;https://www.youtube.com/watch?v=8P0iKiW_3FM&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt; shows how conflicting inputs are acted on and indicated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following text was coughed up by the intertubes and appears to be a description of Airbus sidestick operation.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.2. Dual input detection enhancements&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1. Description As a complement to the active sidestick evaluations, various new features have been developed to improve the&#xA;  crew awareness of dual input situations on the FBW aircraft. The main&#xA;  objective of these features is to provide warnings which will prevent&#xA;  long duration dual input situations. The following visual, aural and&#xA;  tactile cues have been tested with the active participation of pilots&#xA;  from Airbus, airlines (Cathay, DLH, Sabena), unions (ALPA, SNPL,&#xA;  German Cockpit) and Airworthiness Authorities (CEV, CAA, FAA,&#xA;  Transport Canada).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;VISUAL CUE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When both sidesticks are deflected simultaneously (for more than 0.5&#xA;  sec), the CAPT and F/O captions of the Sidestick Priority Light on&#xA;  both glareshields are illuminated flashing in green. As soon as the&#xA;  priority p/b is pressed on either sidestick, the glareshield lights&#xA;  revert to the classical priority configuration (CAPT and arrow or F/O&#xA;  and arrow). The principles of this visual indicator are identical for&#xA;  all FBW aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;AURAL CUE&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A &quot;DUAL INPUT&quot; audio message is triggered when both sidesticks have&#xA;  been simultaneously deflected for a certain time. The timing of the&#xA;  audio message has been adapted on the A320/A321/A31 and A330/A340&#xA;  families due to the different systems architecture such that, on all&#xA;  cases, the message is triggered after the illumination of the&#xA;  glareshield lights. In this way, there is a degree of sequencing such&#xA;  that the aural warning will only be triggered if the dual input&#xA;  situation is prolonged. The &quot;DUAL INPUT&quot; audio is repeated every 5&#xA;  sec. It has the lowest priority of all the audio (voice) messages but&#xA;  can be generated simultaneously with any other non-voice audio&#xA;  warnings. When the priority p/b is pressed on either sidestick the&#xA;  warning is canceled except if it has already started (i.e. it cannot&#xA;  be interrupted).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;TACTILE CUE (BUZZER)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The sidestick is fitted with a small electrical motor which rotates an&#xA;  unbalanced weight and thus generates a vibration of the sidestick. The&#xA;  level of vibration depends on the rotation speed and on the weight of&#xA;  the rotating mass. When both sidesticks are deflected for a certain&#xA;  time, the buzzer on both sidesticks are activated to produce a series&#xA;  of intermittent vibrations. Since the level of buzzer vibration could&#xA;  not be increased at will due to various reasons (e.g. rattling noise&#xA;  on the lateral console) the principle of intermittent &quot;shots&quot; was&#xA;  selected to improve the detection of the buzzer activation. The timing&#xA;  of the buzzer activation has been adapted on all the FBW aircraft such&#xA;  that the buzzer is activated simultaneously or slightly after the&#xA;  illumination of the glareshield lights. When the priority p/b is&#xA;  pressed on either sidestick the buzzer is stopped immediately.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-04-05T16:28:44.417" LastActivityDate="2015-04-05T16:28:44.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13847" PostTypeId="2" ParentId="11857" CreationDate="2015-04-05T16:09:51.863" Score="4" Body="&lt;p&gt;Based on ICAO ( doc9157 Aerodrome design manuel part1 runways), the standard of vertical and horizontal slope of runways is:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XrWSv.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;For Horizontal Slope&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;1-1.5% for code letter C,D,E,F&lt;/p&gt;&#xA;&lt;p&gt;1-2% for code letter A and B&lt;/p&gt;&#xA;&lt;p&gt;Except intersections of another runway/taxiway where slope can be falter&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;And for Vertical Slope&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Slope between max. and min evaluation of the runway centre line should be :&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Code number 4: overall &amp;lt;1%,  1st and 4th quarter &amp;lt;0.8%, the other half &amp;lt;1.25%&lt;/p&gt;&#xA;&lt;p&gt;Code number 3: overall &amp;lt;1%,  1st and 4th quarter &amp;lt;0.8%, the other half &amp;lt;1.25%&lt;/p&gt;&#xA;&lt;p&gt;Code number 1/2: overall &amp;lt;2%&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For slope change between 2 consecutive slope should be:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;lt;1.5% for code number 3/4&lt;/p&gt;&#xA;&lt;p&gt;&amp;lt;2% for code number 1/2&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And for transition from one slope to another should be:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;lt;0.1% per 30m code number 4&lt;/p&gt;&#xA;&lt;p&gt;&amp;lt;0.2% per 30m code number 3&lt;/p&gt;&#xA;&lt;p&gt;&amp;lt;0.4% per 30m code number 1/2&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is the global standard, some aviation authority such as FAA my have stricter rules&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-05T16:09:51.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13848" PostTypeId="2" ParentId="13837" CreationDate="2015-04-05T18:20:55.390" Score="1" Body="&lt;p&gt;Turboprop engines are (generally) powered by centrifugal or axial/centrifugal flow engines. These are smaller (again, generally) than an axial flow engine. This small size allows components to rotate at really, really, really ridiculous speeds, up to 50,000 rpm (maybe more). Spinning a propeller at even 5000 rpm is very inefficient for the few seconds the blades would stay together. The gearbox reduces the rpm to speeds slow enough to design a propeller around.&lt;/p&gt;&#xA;" OwnerUserId="8016" LastActivityDate="2015-04-05T18:20:55.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13849" PostTypeId="1" CreationDate="2015-04-05T18:50:12.210" Score="2" ViewCount="1329" Body="&lt;p&gt;I'm trying to calculate all the expenses to become a pilot in the Philippines.&lt;/p&gt;&#xA;" OwnerUserId="8019" LastEditorUserId="19" LastEditDate="2015-04-05T19:42:49.093" LastActivityDate="2015-04-06T09:20:26.240" Title="How many flying hours does one need to become a commercial pilot in the Philippines?" Tags="&lt;pilots&gt;&lt;philippines&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13850" PostTypeId="2" ParentId="13844" CreationDate="2015-04-05T19:02:35.253" Score="4" Body="&lt;p&gt;I think I'd challenge your assumption of insufficient air traffic capacity.  You could equally well look at it as too many planes wanting to land, or (for NYC at least) insufficient passenger rail service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, have you looked at land prices in the vicinity of NYC or London?  Perhaps in some countries you can just seize land to build airports, over the objections of the people living there.  In the US (and presumably the UK, though I'm not certain), it's much more difficult to obtain, and should properly involve paying a fair market price - after long and expensive legal battles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you have to consider trip duration.  It's not just time spent flying, but time getting to and from the airport.  In NYC, it's IIRC about a 15 minute bus ride from LaGuardia to Manhattan, and I think not much more from JFK.  Put the airport way out in the country, and people would spend an hour or two just getting there, negating the speed advantage of air travel for short &amp;amp; medium length flights.&lt;/p&gt;&#xA;" OwnerUserId="6968" LastActivityDate="2015-04-05T19:02:35.253" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13851" PostTypeId="1" AcceptedAnswerId="13852" CreationDate="2015-04-05T21:40:25.377" Score="9" ViewCount="1309" Body="&lt;p&gt;If I compare taxiing of airplanes with, for example, driving cars, drivers in the latter case regularly check the positions of their cars relative to others by using the different available mirrors. However, that is not an option in airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just thinking about all potential possibilities, I imagine that airplanes probably rely on the airport control tower for making decisions that require the knowledge of the relative positions of other airplanes. Also, collision–prevention devices provide part of that information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are airplane pilots aware of other nearby planes during taxi? Do they need that information, or is not useful for them as instructions are sent by the control tower?&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="2143" LastEditDate="2015-12-24T01:07:47.887" LastActivityDate="2015-12-24T01:07:47.887" Title="How do pilots maintain awareness of other airplanes during taxi?" Tags="&lt;air-traffic-control&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13852" PostTypeId="2" ParentId="13851" CreationDate="2015-04-05T22:25:04.793" Score="7" Body="&lt;p&gt;At a large airport, all aircraft movements are coordinated by the ATC tower on the ground frequency. Aircraft should never move without authorization from the controller. The tower will issue instructions to aircraft that might look something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxi to Gate 1 via Alpha, Alpha 1, Lima 3, cross runway 24, hold short Delta.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These names correspond to markings on the ground that match up with the airport taxiing maps. By talking with the pilots, the controllers are able to build up a map of where aircraft are. It also helps that they can look out the window and see the aircraft on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At airports without a tower, taxiing isn't much of an issue. There aren't many planes around, and there's generally only one runway and not many taxiways. Nevertheless, aircraft taxiing when there is no ground controller comply with &quot;see and be seen&quot; by looking outside and turning on aircraft lights. Furthermore, if the aircraft has a radio, it should self-announce its movements on the ground.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3504" LastEditDate="2015-11-22T22:03:07.180" LastActivityDate="2015-11-22T22:03:07.180" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13853" PostTypeId="1" AcceptedAnswerId="13872" CreationDate="2015-04-05T22:38:14.047" Score="6" ViewCount="2311" Body="&lt;p&gt;In most weather reports I see &quot;Outlook VFR&quot; and I am not sure what that means and as a pilot what should I expect? What is an &quot;outlook&quot; and what does it mean when it is &quot;VFR&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, what does 'OTLK... VFR' mean in weather reports?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="5592" LastEditDate="2015-04-06T16:45:53.763" LastActivityDate="2015-04-06T17:05:58.260" Title="What does 'outlook ... VFR' mean?" Tags="&lt;weather&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13854" PostTypeId="2" ParentId="13853" CreationDate="2015-04-05T23:54:22.573" Score="4" Body="&lt;p&gt;VFR stands for Visual Flight Rules, in which you can expect VMC - or Visual Meteorological Conditions. In other words, good weather conditions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It is the opposite of instrument meteorological conditions (IMC). The boundary criteria between IMC and VMC are known as the VMC minima and are defined by: visibility, cloud ceilings (for takeoffs and landings), and cloud clearances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA has regulations (14 CFR 91.155) on VFR Weather Minimums, and the following is taken from the &lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/25/185/VFR%20Weather%20Minimums.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR Weather Minimums PDF&lt;/a&gt; the FAA publishes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cFfCo.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VFR flight is based on the principle of “see and avoid.” The presumption&#xA;  made in establishing the basic VFR weather minimums is that aircraft&#xA;  flying at lower altitudes (i.e., below 10,000 MSL) and/or in airspace with&#xA;  radar approach control and/or an operating control tower (i.e., Class B, C,&#xA;  and D airspace) will be moving more slowly, or that they will be under&#xA;  positive control. Consequently, these aircraft do not need as much flight&#xA;  visibility or as much distance from clouds to see and avoid other traffic.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Aircraft operating at higher altitudes (i.e., Class E airspace above 10,000&#xA;  MSL) are likely to be not only faster, but also operating on instrument&#xA;  flight plans. The rationale for greater visibility and more distance from&#xA;  clouds when flying above 10,000 MSL is to give VFR pilots more time to&#xA;  see and avoid faster aircraft that are popping in and out of clouds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-04-06T00:01:39.763" LastActivityDate="2015-04-06T00:01:39.763" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="13855" PostTypeId="1" AcceptedAnswerId="13858" CreationDate="2015-04-06T01:00:01.723" Score="6" ViewCount="1129" Body="&lt;p&gt;I imagine plane having only four flaps in the back (one on top, bottom, left and right), similar to ailerons but longer and narrower. They can open from the fuselage to correct the plane's yaw or angle. I predict that this would increase efficiency of the plane since there's no drag from the horizontal and vertical stabilizers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can this design work?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastEditorUserId="65" LastEditDate="2015-06-12T18:42:48.663" LastActivityDate="2021-05-08T18:24:09.830" Title="Why can't planes use only flaps in the tail section instead of stabilizers?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13856" PostTypeId="1" AcceptedAnswerId="13857" CreationDate="2015-04-06T01:55:19.933" Score="14" ViewCount="2773" Body="&lt;p&gt;Yesterday I was on a passenger plane flying at 35000 feet from Denver to JFK on a fairly clear day. Just west of Sioux City, we made a relatively sharp, but short, right turn for whatever reason (may be unrelated). I happened to be looking out my window and caught what appeared to be a military fighter jet (presumably from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sioux_City_Air_National_Guard_Base&quot;&gt;Air Force base&lt;/a&gt; there) flying in the opposite direction. It blew past my field of vision in a fraction of a second, slightly below us and off to the right, close and fast enough to startle me. It left a beautiful set of trails but, while my distance judgments aren't very good from a plane, appeared to be no more than ~1000 feet away from us (based on its size, I imagined it to be about 4-5 NYC city blocks away, that's my only reference). The passing aircraft's trails were dead straight at least as far back as they extended before dissipating. I didn't get a chance to ask the pilot about it after the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My only knowledge of separation laws is from wikipedia, which seems to state a &lt;a href=&quot;http://en.wikipedia.org/wiki/Separation_%28aeronautics%29#Vertical_separation&quot;&gt;2000 foot limit above 29000 feet&lt;/a&gt;.  I absolutely might be misjudging distance, but this aircraft seemed to be well under a half a mile away. So my question is: Are there a different set of separation laws for military aircraft, or perhaps are existing laws just not as strictly followed / enforced by the military? Would the pilot of one of the aircraft expect some sort of reprimand later? Was this a normal occurrence or was it a close call?&lt;/p&gt;&#xA;" OwnerUserId="1046" LastEditorUserId="1046" LastEditDate="2015-04-06T03:39:35.670" LastActivityDate="2015-04-06T03:39:35.670" Title="Are there laws about how close military aircraft can fly to passenger jets, and are they enforced?" Tags="&lt;military&gt;&lt;separation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13857" PostTypeId="2" ParentId="13856" CreationDate="2015-04-06T02:43:28.610" Score="15" Body="&lt;p&gt;This is somewhat speculation, but here's what I think happened:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You were flying at around 35,000 feet, in &lt;a href=&quot;http://en.wikipedia.org/wiki/Reduced_vertical_separation_minima&quot;&gt;RSVSM airspace&lt;/a&gt;. The fighter jet was correctly on track 1000 feet below you. Without any other guides of distance, you tried to judge its distance by apparent size compared to real size. You might have underestimated the size of a fighter jet; they're typically about 50 feet long. I know I, for one, always thought they were much smaller. Thus what looked like &quot;slightly below&quot; was actually 1000 feet below you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the more general question you posted: the military can get as close to other aircraft as they damn well please, through a procedure called Military Assumes Responsibility for Seperation of Aircraft, or &lt;a href=&quot;http://en.m.wikipedia.org/wiki/MARSA_%28aviation%29&quot;&gt;MARSA&lt;/a&gt; (thanks to fooot for pointing this out!). Generally this only happens with a civilian aircraft during an interception. I don't know the specific procedures that are followed, but I know that in the past intercepting pilots have gotten close enough to pick out individuals in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for enforcement, the question is kind of null. Generally, if civilian pilots violate separation without putting anyone in danger, the air traffic controller will just yell at them for a bit, but it does depend on the case. The FAA doesn't have much authority over the military, however. If the air traffic controller passed the information on to the military, perhaps there could be some sort of corrective action, but at this point I'm just guessing. &lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-04-06T03:09:38.647" LastActivityDate="2015-04-06T03:09:38.647" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13858" PostTypeId="2" ParentId="13855" CreationDate="2015-04-06T03:01:27.703" Score="12" Body="&lt;p&gt;Your question is partly covered &lt;a href=&quot;https://aviation.stackexchange.com/q/8602/1696&quot;&gt;here&lt;/a&gt; regarding why the vertical stabilizer is important. The empennage (tail surfaces) of conventional planes provides both &lt;a href=&quot;https://aviation.stackexchange.com/q/7528/1696&quot;&gt;passive&lt;/a&gt; and active stability. Like the feathers on an arrow (which is where the word empennage comes from), they help the airplane to remain pointed in the direction of flight as well as providing active control surfaces. The cost of providing stability is added weight and drag, but if the surfaces are removed, the stability aspect will need to be provided manually, or alternately. This is how unconventional aircraft like the B-2 flying wing, or even &lt;a href=&quot;https://aviation.stackexchange.com/q/8049/1696&quot;&gt;modern fighter aircraft&lt;/a&gt;, are able to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, yes, we can fly airplanes without conventional tail surfaces. Some designers like &lt;a href=&quot;https://en.wikipedia.org/wiki/Burt_Rutan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Burt Rutan&lt;/a&gt; have created unconventional designs for general aviation. However, design changes will also have drawbacks. At the very least these designs behave differently than conventional planes, which requires special attention. The strange appearance is also reason for some pilots to distrust them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane is going to be unstable without computer control, that &lt;a href=&quot;https://aviation.stackexchange.com/q/1801/1696&quot;&gt;introduces safety problems&lt;/a&gt;. In military aircraft the pilots can eject when &lt;a href=&quot;http://en.wikipedia.org/wiki/2008_Andersen_Air_Force_Base_B-2_accident&quot; rel=&quot;nofollow noreferrer&quot;&gt;issues arise&lt;/a&gt;. But unlike modern commercial planes, the pilots cannot simply take over control if the computers fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also an aerodynamic issue with what you propose. Conventional control surfaces deflect the entire surface, so air continues to flow past both sides. However, if you only deflect one side of the surface, air is only flowing past the outer face. This acts like a spoiler and creates extra drag. Though this drag will be the force controlling the plane, it is not as efficient as moving a control surface. &lt;a href=&quot;https://aviation.stackexchange.com/a/13861/1696&quot;&gt;As Peter Kämpf pointed out&lt;/a&gt;, it is much more feasible to &lt;a href=&quot;http://aviationweek.com/awin-featured-story/boeing-nasa-test-active-flow-control-tail&quot; rel=&quot;nofollow noreferrer&quot;&gt;increase the effectiveness of the existing surfaces&lt;/a&gt; than to eliminate them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/8649/1696&quot;&gt;Modern airliners&lt;/a&gt; represent a compromise between efficiency and safety based on currently available technology. Although alternate designs &lt;a href=&quot;https://aviation.stackexchange.com/q/12782/1696&quot;&gt;have been proposed&lt;/a&gt;, these configurations create their own unique problems.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-06T15:59:02.487" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13859" PostTypeId="1" AcceptedAnswerId="13865" CreationDate="2015-04-06T05:00:54.370" Score="6" ViewCount="4245" Body="&lt;p&gt;Are there any rules for driving a passenger vehicle on taxiways and/or runways at an uncontrolled airport in the USA?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2015-04-06T05:33:57.347" LastActivityDate="2018-08-22T14:06:55.207" Title="What are the rules for driving at a public, uncontrolled airport in the USA?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13860" PostTypeId="1" AcceptedAnswerId="13862" CreationDate="2015-04-06T06:04:04.960" Score="12" ViewCount="19585" Body="&lt;p&gt;What equipment is installed in passenger aircraft for catering the passenger?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="7532" LastEditDate="2015-10-01T00:49:53.190" LastActivityDate="2015-10-01T00:49:53.190" Title="What does a passenger aircraft galley ('kitchen') look like?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13861" PostTypeId="2" ParentId="13855" CreationDate="2015-04-06T07:04:08.800" Score="8" Body="&lt;p&gt;First let me clarify: You propose four moving surfaces which extend as needed (I guess that is what you mean by &amp;quot;open from the fuselage&amp;quot;) from the fuselage?&lt;/p&gt;&#xA;&lt;p&gt;Yes, theoretically it can work, but the flaps need to be as big as the surfaces they are intended to replace and need to be out in the airstream  all the time. That would look remarkably like what we currently have, so any hopes of significantly reducing drag are unfounded.&lt;/p&gt;&#xA;&lt;p&gt;Now there is a scenario where drag savings on the flaps are possible. Tail surfaces don't work at their maximum or even optimum lift (optimum meaning at their best lift to drag ratio) most of the time, so the degree of extension could be smaller, and less surface area is exposed. But where do you stow all the remaining part of the flap? Now you need to make the fuselage that much bigger, so you lose in fuselage drag what you gain in tail area drag. Add to this the weight of the kinematics for moving the flaps, and the conventional design looks ever more attractive.&lt;/p&gt;&#xA;&lt;p&gt;As @fooot has pointed out, this scenario needs computer control and added layers of safety like secondary means of flap movement if the primary actuators fail.&lt;/p&gt;&#xA;&lt;p&gt;If no asymmetric thrust scenario is possible, &lt;a href=&quot;https://aviation.stackexchange.com/questions/12055/why-isnt-it-possible-to-locate-the-rudder-in-front-of-an-airplanes-center-of-g/12103#12103&quot;&gt;earlier designs have already proposed to do away with the whole vertical tail&lt;/a&gt; and replace it with a small, computer-controlled fin at the nose, yielding significant weight and drag savings.&lt;/p&gt;&#xA;&lt;p&gt;Aircraft designers have constantly tried to reduce tail surfaces to the minimum they can get away with. Please look at the picture of the An-70 below closely: The horizontal tail has slats which open forward and up, so the tail surface can produce more downforce when flaps are extended. This is a trick to reduce the tail area, which doesn't need to produce much downforce during most of the flight, at the expense of more drag with flaps extended and more moving parts.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0U3Ug.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0U3Ug.jpg&quot; alt=&quot;An-70 at Paris Airshow in 2000&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;An-70 at Paris Airshow in 2000 (own work)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-05-08T18:24:09.830" LastActivityDate="2021-05-08T18:24:09.830" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="13862" PostTypeId="2" ParentId="13860" CreationDate="2015-04-06T08:45:56.700" Score="16" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SsEmc.jpg&quot; alt=&quot;Lufthansa A380&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft Kitchen is known as the &lt;strong&gt;Galley&lt;/strong&gt; and the picture is from a Lufthansa A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some equipment you will see here are: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Food Oven&lt;/strong&gt;, the door with a black knob in the middle of the picture.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Coffee Machine&lt;/strong&gt;, with the pot, in the right side of the picture.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Large Trolleys&lt;/strong&gt;, filled with food and/or drinks, on the floor. Weight about 25kg empty.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Trash Bin&lt;/strong&gt;, the darker grey unit on the right on the floor. Wheeled off like everything else. Some have proper trash electric trash compactors as well in trolley format.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Fuse Panel&lt;/strong&gt;, located in the middle along the top row. There is in general a fair bit of power going into this area. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Smaller Storage Containers&lt;/strong&gt;, that can handle drinks or bottles for instance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;General Storage Space&lt;/strong&gt;: The galley also provides a bit of space for anything from the children's toys and newspapers to emergency equipment. You can see some compartments for this in the upper-left corner and a symbol that a smoke hood is stored in one of them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Quick design comment:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Aircraft galleys are hotspots for corrosion due to the liquid in the area and is the cause for particular attention during maintenance. Most aircraft galleys are generally very similar in design.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Galley equipment comes in 2 basic universal standards - namely ATLAS and KSSU. These have their origins in legacy maintenance resource pools (ATLAS = Alitalia, TAP, Lufthansa, Air France, Sabena and KSSU = KLM, Swissair, SAS, UTA) and have subsequently developed into industry standards to enable modular equipment interchange.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These standards for instance specify the height, width and depth of trolleys. I gather that ATLAS standard is more prevalent (80% of galleys by one source) but both exist. Other ideas and concepts have popped up but since changing the stuff is very expensive there's not been a real push for it. I think I've also read that the original standard was pretty well thought through.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Naturally, this is a long-distance galley that will serve usually two meals. Equipment and size are scaled to the needs of the airline and can vary greatly between operators.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-04-07T10:29:19.783" LastActivityDate="2015-04-07T10:29:19.783" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13863" PostTypeId="2" ParentId="13849" CreationDate="2015-04-06T09:05:09.627" Score="1" Body="&lt;p&gt;While CAAP seems to be pretty (or even very) vague on the topic, this is what I've been able to find: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To start with the private pilots license:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You must also complete the required minimum of 40 hours of widespread flight training. The hours of flight time consists of at least 20 hours of dual flight instruction, at least 10 hours of solo flight, and 10 hours of which can be solo flights or dual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Then you will need to build on this to get a commercial pilots license:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You will need about 220 hours of total flight time to get your CPL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;* Another source suggests you need a minimum of 150 hours. Be aware however that this is not an exact science: Even for the PPL it can take 60 hours to 'get the feeling for it', so it is difficult to estimate exactly how much you will need. While I'm not a pilot myself I think it's a good idea to be on the conservative side and overestimate the hours you will need for a PPL and CPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wccaviation.com/index.php/blog/155-quick-guide-in-getting-your-pilot-licenses-in-the-philippines&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is probably unfortunately what you have also been able to find. It is however a very good idea to go past the flight school in person and talk to them about this topic, since it's uncommon, and they can probably give you a better estimate. Be aware that there can be several more costs that are not visible at first sight (checkrides for instance) that can add to the tally so even the ones that appear the cheapest are not.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-04-06T09:20:26.240" LastActivityDate="2015-04-06T09:20:26.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13865" PostTypeId="2" ParentId="13859" CreationDate="2015-04-06T10:09:47.693" Score="8" Body="&lt;p&gt;The FAA has issued an &lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/airports/runway_safety/media/ground_vehicle_guide_proof_final.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Guide to&#xA;Ground Vehicle&#xA;Operations -&#xA;A Comprehensive Guide&#xA;to Safe Driving on the&#xA;Airport Surface&lt;/a&gt;&lt;/strong&gt; which covers what they call &quot;non-towered airports&quot;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NON-TOWERED AIRPORTS&lt;br&gt;&#xA;  When the control tower is closed or if there is no tower, the airport&#xA;  is referred to as non-towered. At a non-towered airport, you do not&#xA;  need controller permission before entering a runway or taxiway.&#xA;  Below are some best practices for operating on a non-towered&#xA;  airport:  &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;When you approach the runways and taxiways, STOP, LOOK&#xA;  both ways, and LISTEN for aircraft that are landing or taking&#xA;  off. Vehicle windows should be open to do this properly.&lt;/li&gt;&#xA;  &lt;li&gt;Alert others when you are using a taxiway or runway by&#xA;  always making an announcement on the radio before you&#xA;  enter. Be specific with your location and intentions.&lt;/li&gt;&#xA;  &lt;li&gt;Always yield the right-of-way to taxiing aircraft and give them&#xA;  plenty of room. If an aircraft is headed toward you on the&#xA;  same taxiway, move out of the aircraft’s way.&lt;/li&gt;&#xA;  &lt;li&gt;Always carry a radio tuned to the airport’s Common Traffic&#xA;  Advisory Frequency (CTAF) or UNICOM.&lt;/li&gt;&#xA;  &lt;li&gt;If an aircraft is about to land on a runway that you need to&#xA;  cross, stop well clear of the runway. Continue to yield to the&#xA;  aircraft until it has landed and taxied off of the runway.&lt;/li&gt;&#xA;  &lt;li&gt;Be aware that some&#xA;  aircraft at non-towered&#xA;  airports are not equipped&#xA;  with radios.&lt;/li&gt;&#xA;  &lt;li&gt;Before you cross a runway, ensure that no potentially&#xA;  conflicting aircraft are taxiing, landing or taking off. Be&#xA;  aware of aircraft at non-towered airports that frequently make&#xA;  touch-and-go landings (immediately after landing, full power&#xA;  is applied and the aircraft takes off again).&lt;/li&gt;&#xA;  &lt;li&gt;If your vehicle has a rotating beacon, be sure to turn it on&#xA;  anytime you are on the airport surface. Turn on headlights as&#xA;  well, being careful not to blind any pilots in the area. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-04-06T10:09:47.693" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13866" PostTypeId="1" CreationDate="2015-04-06T12:07:32.837" Score="13" ViewCount="3289" Body="&lt;p&gt;I have flight logs for a WW II B-24 navigator who flew with a combat crew in China Burma India.  There is a column for number of landings.  The entries range from 1 to 5 or 6, mostly 1 or 2.  The time can be as long as 8:00 to 10:00 or more.  Why is the number of landings recorded?  Is that still done today?&lt;/p&gt;&#xA;" OwnerUserId="8023" LastEditorUserId="65" LastEditDate="2015-04-06T13:44:02.857" LastActivityDate="2020-09-26T17:07:49.997" Title="Why are number of landings logged?" Tags="&lt;landing&gt;&lt;logging&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13867" PostTypeId="2" ParentId="13866" CreationDate="2015-04-06T12:30:14.603" Score="18" Body="&lt;p&gt;Yes, it's still done today, at least in military aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's to ensure that the undercarriage does not excede the number of landings it has to endure before being checked/overhauled/replaced. Landing an aircraft can typically be the most stressful regime of flight in terms of loading of certain bits of the aircraft, so it is pertinent to log how many times it happens per flight.&lt;/p&gt;&#xA;" OwnerUserId="7169" LastActivityDate="2015-04-06T12:30:14.603" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13868" PostTypeId="2" ParentId="13866" CreationDate="2015-04-06T13:07:06.627" Score="14" Body="&lt;p&gt;I'm not sure if this is specifically a military question or a general question. In general aviation (FAA) you are required to do a certain number of landings every 3 months to stay current. So landings are logged for this reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific regulation is &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.57&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.57 (a) (1)&lt;/a&gt;, which says (&lt;strong&gt;emphasis added&lt;/strong&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[…] no person may act as a pilot in command of an aircraft carrying&#xA;  passengers or of an aircraft certificated for more than one pilot&#xA;  flight crewmember unless that person has made at least &lt;strong&gt;three&#xA;  takeoffs and three landings within the preceding 90 days&lt;/strong&gt; […]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not yet rated for IFR, so I'm not sure on the specifics about IFR currency mentioned in this regulation. The currency for VFR related flight differs from day and night; however, 3 night landings in 90 days will count to keep you current, while 3 day landings will only keep you current for daytime VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A note on military training:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was able to find &lt;a href=&quot;http://www.ibiblio.org/hyperwar/AAF/VI/AAF-VI-17.html&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; book/article that alludes to the training of navigators during the second world war; on P.585:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Before 1933 instruction in navigation was given only as part of pilot training. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the individual in question had a military career and joined before '33 he may have been a pilot first and simply continued with the same log book. Why the landings were logged may just be force of habit. Either way its an interesting read on how difficult it was to be a navigator at the time and exactly what it took to become one. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="4474" LastEditDate="2015-04-07T00:50:25.303" LastActivityDate="2015-04-07T00:50:25.303" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13870" PostTypeId="1" CreationDate="2015-04-06T13:57:12.163" Score="0" ViewCount="2107" Body="&lt;p&gt;If $$lift=weight * cos(angle)$$ this means that lift is less than weight during takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone please explain me why it is so&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ANpdn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8025" LastEditorUserId="419" LastEditDate="2015-04-06T14:08:59.473" LastActivityDate="2015-04-06T14:21:45.943" Title="How comes lift is less than weight on take-off?" Tags="&lt;takeoff&gt;&lt;weight-and-balance&gt;&lt;lift&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-04-06T15:17:57.620" ContentLicense="CC BY-SA 3.0" />
  <row Id="13871" PostTypeId="2" ParentId="13870" CreationDate="2015-04-06T14:21:45.943" Score="0" Body="&lt;p&gt;Indeed, what puzzles a lot of people is that excess lift (excess as in more than we need for weight) it not what makes an aircraft climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, a take-off is a dynamic situation which doesn't really call for a balance of forces and momentum, so the situation is a bit more complicated to explain, but let's try a thought:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine it this way: If lift &gt; weight you will accelerate 'up-'wards (ie. balloon style). Air will come not only from the front moving backwards, but also from above moving below. The relative air moving past your wing is now coming from front and slightly above. This decreases your angle of attack and thus decreases lift, usually up to the point where lift = weight again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If lift&amp;lt; weight, the opposite happens (ie. accelerate downwards) and air will move from below the wing towards up. This increases the angle of attack, increases the lift, and again lift will match the weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's basically a statically stable system, where the only really stable position ,if you think about, is when lift equals weight (in straight-level flight, mind you. For climbing and descending you have the formula stated in your question).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to climb, increasing lift is not the way to go !&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2015-04-06T14:21:45.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13872" PostTypeId="2" ParentId="13853" CreationDate="2015-04-06T16:29:18.443" Score="6" Body="&lt;p&gt;Outlook VFR is usually found in the so called &lt;strong&gt;&quot;Area Forecast&quot;&lt;/strong&gt;. It is the last part of the portion which describes clouds and weather, which could affect VFR operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The area forecast for every region is valid for 12 hours, &lt;strong&gt;followed by a 6 hour categorical outlook&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three types of outlooks, &lt;strong&gt;VFR&lt;/strong&gt;, &lt;em&gt;IFR&lt;/em&gt; and &lt;em&gt;MVFR&lt;/em&gt; (marginal VFR). As mentioned in &lt;a href=&quot;http://www.mypilotstore.com/mypilotstore/sep/1270&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jeppesen's Guided Flight Discovery Instrument/Commercial Manual&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A ceiling less than 1,000 feet and/or visibility less then 3 miles is&#xA;  considered IFR. Marginal VFR areas are those with ceilings from 1,000&#xA;  to 3,000 feet and/or visibility between 3 and 5 miles.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Everything &quot;better&quot; (as in higher ceiling and/or visibility) is considered VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an extract from an Area Forecast:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;CLDS/WX VALID UNTIL 062100...OTLK VALID 062100-070300&#xA;[...]&#xA;NRN PEN...BKN010-020 TOP 100. OCNL VIS 3SM BR. BECMG 1214 BKN025&#xA;TOP 120. ISOL -SHRA. 18Z BKN040 TOP FL220. WDLY SCT -SHRA/TSRA.&#xA;CB TOP FL420. OTLK...VFR TIL 02Z SHRA TSRA.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The first part is an extract from the Heading Section. here you find the time for which the Clouds and Weather part as well as the Outlook part is valid.&#xA;The second part consist of the mentioned Clouds and Weather as well as the Outlook. I'm not going to decipher the whole thing now, but here is a short explanation: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the more detailed forecast, valid from the time of loading the Area Forecast to &lt;code&gt;062100&lt;/code&gt;, which means the 6th of the month, 21:00 Zulu time. After that, from &lt;code&gt;062100-070300&lt;/code&gt; so from the 6th at 21:00 Zulu until the 7th at 03:00 Zulu, the outlook is what counts. In this case it is VFR until the 7th of the month at 02:00 Zulu, where showers and thunderstorms (in connection with rain) are expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion: The outlook gives a general idea what the weather will be like up to 6 hours &lt;em&gt;after&lt;/em&gt; the forecast part of the Are Forecast. This can help in flight planning.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information about VFR refer to &lt;a href=&quot;https://aviation.stackexchange.com/a/13854/65&quot;&gt;DannyBeckett's detailed answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-06T17:05:58.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13873" PostTypeId="2" ParentId="7853" CreationDate="2015-04-06T18:43:24.930" Score="5" Body="&lt;p&gt;I landed there back from Heathrow in 1994 on an El Al Boeing 747-200 and departed on same a week later. Can't say if a 400 series would get in and out but I don't see why not.&lt;/p&gt;&#xA;" OwnerUserId="8028" LastActivityDate="2015-04-06T18:43:24.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13874" PostTypeId="2" ParentId="13866" CreationDate="2015-04-06T18:47:10.330" Score="0" Body="&lt;p&gt;I suspect it has to do with the fact that pilots want/need records of that for certification purposes and Pilot In Command can  change in the middle of a flight. Seems silly for a navigator though. &lt;/p&gt;&#xA;" OwnerUserId="6854" LastActivityDate="2015-04-06T18:47:10.330" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13875" PostTypeId="2" ParentId="13866" CreationDate="2015-04-06T20:10:39.617" Score="3" Body="&lt;p&gt;Landing is not the easiest thing on an airframe! It imparts a lot of stress, and everything we build is designed and evaluated by some statistician to endure a certain number of uses + or - some standard deviation that he/she defines. Even the keys on your keyboard are meant to endure a certain number of presses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, if you CAN collect data that you suspect may be useful later, why not? You never know when you may want to use it for something you didn't intend to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure about the navigator though.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2015-04-06T20:10:39.617" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13876" PostTypeId="1" AcceptedAnswerId="13881" CreationDate="2015-04-06T20:53:01.207" Score="18" ViewCount="30700" Body="&lt;p&gt;I saw a vortex generator mentioned in an aircraft listing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a vortex generator?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="22726" LastEditDate="2019-08-26T01:14:45.690" LastActivityDate="2019-11-01T22:39:00.163" Title="What is a vortex generator?" Tags="&lt;aerodynamics&gt;&lt;aircraft-systems&gt;&lt;vortex-generators&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13877" PostTypeId="2" ParentId="13876" CreationDate="2015-04-06T21:10:06.157" Score="2" Body="&lt;p&gt;They're little winglet type things that you install on the surface of the wings to encourage laminar flow of air and to discourage stalls. Think of them as &quot;cheap insurance for when you're not monitoring your airspeed very well&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit for future readers: Should be attached flow, not laminar flow. See below comments for explanation.&lt;/p&gt;&#xA;" OwnerUserId="6840" LastEditorUserId="3048" LastEditDate="2017-06-01T13:38:08.300" LastActivityDate="2017-06-01T13:38:08.300" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13878" PostTypeId="1" CreationDate="2015-04-06T22:02:15.207" Score="7" ViewCount="1168" Body="&lt;p&gt;I am taking a trip from somewhere on the Phoenix sectional up to the grand canyon.  I wanted to just splice the two sectionals together on my computer and then print them out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I picked a coordinate to align (as you can see in the first image), and with that coordinate aligned, almost nothing else on the map matched up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why aren't the sectional maps standardized to people can do this more easily?  I would have loved to make a &quot;custom&quot; map out of the Phoenix sectional, Vegas sectional, and Grand Canyon map, but it's virtually impossible without modifying them further, which I don't want to do in case of messing up the scale and/or orientation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zimhd.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/1LKyw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="62" LastEditDate="2015-04-07T19:52:17.337" LastActivityDate="2017-06-03T00:01:57.127" Title="Why can't I exactly match the same points on different VFR sectional charts?" Tags="&lt;aeronautical-charts&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13879" PostTypeId="1" AcceptedAnswerId="13887" CreationDate="2015-04-06T22:33:58.053" Score="3" ViewCount="2439" Body="&lt;p&gt;British Airways operate a flight from Edinburgh airport to Heathrow airport every morning in a 767. Aren't these wide-bodies meant for long haul flights? &lt;/p&gt;&#xA;" OwnerUserId="7803" LastActivityDate="2015-04-07T00:48:55.363" Title="Why does British Airways fly a short haul flight in a B767?" Tags="&lt;boeing&gt;&lt;boeing-767&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2015-04-07T03:04:02.020" ContentLicense="CC BY-SA 3.0" />
  <row Id="13880" PostTypeId="2" ParentId="13879" CreationDate="2015-04-06T22:40:58.577" Score="6" Body="&lt;p&gt;The size of the airplane mostly determines how many people it can hold (around 275 passengers for a B767).  If Edinburgh to Heathrow is common route for businessmen and woman who commute often then using a larger plane is more economical for the airline.  Using something such as a Bombardier Q400 which is a common &quot;puddle jumper&quot; airplane might cost less per trip, but it would need to make significantly more trips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Q400 holds around 85 passengers, so you would need to make over three trips in a Q400 to transport the number of people who could fit in a single 767.  &lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2015-04-06T22:40:58.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13881" PostTypeId="2" ParentId="13876" CreationDate="2015-04-06T23:22:30.473" Score="17" Body="&lt;p&gt;To be more general, a vortex generator is a small angled plate installed on an outer surface of an aerodynamic body. The angle of the plate causes the air to swirl, creating a vortex behind it. This effect allows the air flow to remain &quot;attached&quot; to the surface even at points where the flow without a vortex would separate from the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most common uses of vortex generators is on aircraft wings forward of the ailerons. When the aircraft wing &lt;a href=&quot;https://aviation.stackexchange.com/q/6366/1696&quot;&gt;stalls&lt;/a&gt;, the flow detaches from the wings. This means that the flow will detach before it reaches the ailerons, making them ineffective. The use of vortex generators helps the ailerons to provide control even if the rest of the wing is stalled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eoPL8.jpg&quot; alt=&quot;Flow with and without vortex generators in stall&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.aerospaceweb.org/question/aerodynamics/q0255.shtml&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, these also add drag, even when the wing is not stalling, so they are only added where needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also used in other places, such as the engine, as in &lt;a href=&quot;https://aviation.stackexchange.com/questions/13876/what-is-a-vortex-generator#comment31068_13876&quot;&gt;Farhan's comment above&lt;/a&gt;, and also &lt;a href=&quot;http://www.b737.org.uk/fuselage.htm#AFT_BODY_VORTEX_GENERATORS&quot; rel=&quot;noreferrer&quot;&gt;on the tail of the 737&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-06T23:22:30.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13882" PostTypeId="1" AcceptedAnswerId="13903" CreationDate="2015-04-06T23:25:14.163" Score="15" ViewCount="16857" Body="&lt;p&gt;When ATC mention 'radar contact', what does that mean? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In what conditions ATC might contact you and mention 'radar contact' in the call? and what would be the appropriate responses? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="19" LastEditDate="2017-06-02T07:41:22.783" LastActivityDate="2018-11-29T21:26:08.510" Title="What does &quot;radar contact&quot; mean in ATC calls?" Tags="&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13883" PostTypeId="2" ParentId="13882" CreationDate="2015-04-07T00:03:54.680" Score="8" Body="&lt;p&gt;No specific response is typically necessary (although acknowledging that you heard the transmission with a callsign or &quot;roger&quot; is appropriate).  The call means that the controller sees your aircraft on radar &amp;amp; has confirmed that &quot;this&quot; target is &quot;that&quot; aircraft, i.e. your aircraft.  He is now capable of providing ATC services that require the use of radar, such as radar vectors, separation, traffic calls, minimum altitude monitoring, etc.  Not saying that he necessarily IS providing all of those things; there's a little bit of context to such things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also hear, &quot;radar contact lost&quot; either when you are below the radar horizon due to terrain, or over the water too far away from from the radar site.  This means that you're now, if flying IFR, operating under non-radar IFR rules, and things like making position reports at the mandatory reporting points now applies.  (You don't have to make those reports while in radar contract.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, you may also (rarely) hear a military fighter call &quot;radar contact&quot; in response to a traffic call, meaning that he sees the traffic on radar, but not visually.  Not sure if that's standard terminology for them in an ATC environment or not, but I've heard it a few times.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-04-07T16:09:13.123" LastActivityDate="2015-04-07T16:09:13.123" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13884" PostTypeId="2" ParentId="13878" CreationDate="2015-04-07T00:31:35.933" Score="2" Body="&lt;p&gt;There are a few reasons that may cause this. First off I assume you are getting your images from &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/vfr/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; in which case if you look at the 2 PDF downloads in question the maps were issued on different dates. Although its unlikely it is possible that things were moved on the map between these 2 issue dates. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cant tell where you are trying to join the maps but if you are trying to join them mid map (not edge to edge) you may have issues even though they should line up. &lt;a href=&quot;http://en.wikipedia.org/wiki/Map_projection&quot; rel=&quot;nofollow&quot;&gt;This&lt;/a&gt; is a decent write up of the different kinds of map projections and how distortion comes into play when projecting a spherical surface on a flat piece of paper. This distortion could cause some of the issues. I would also thing some error can end up in maps when they are printed. If you use apps like foreflight or the like you will see that the points which are often GPS based dont always line up perfectly with the map.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, you should NOT make your own maps to be used for actual navigation. There are many issues this could create that I will not go into as it does not have to do with the answer to the question.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-04-07T00:37:34.343" LastActivityDate="2015-04-07T00:37:34.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13885" PostTypeId="1" AcceptedAnswerId="13890" CreationDate="2015-04-07T00:45:02.307" Score="5" ViewCount="10927" Body="&lt;p&gt;To clarify the question, I mean the type of wing used on a Concorde or a fighter jet, vs a glider's long and thin ones. What is the aerodynamic reason for using a short wing when the plane is faster?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastEditorUserId="2176" LastEditDate="2015-06-12T18:52:42.190" LastActivityDate="2017-06-08T03:04:07.363" Title="What's the advantage of using short wings rather than long wings?" Tags="&lt;aircraft-design&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13886" PostTypeId="2" ParentId="2094" CreationDate="2015-04-07T00:45:08.623" Score="2" Body="&lt;p&gt;To backup flyingfisch, the angle of attack (AoA) sensor is the only sensor used to determine aural stall warning. The AoA sensors were operating correctly in the case of AF447. The failure mode of sensors due to ice crystal icing is typically limited to those probes which collect by way of geometry such as pitot and TAT probes. Static ports and alpha probes seem unaffected. The aural Stall warning system in Alternate law is purely a limit AoA, and that limit is primarily determined by Mach; it reduces significantly at high mach due to compressibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For AF447, the stall warnings stopped when the limit of the AoA probes were exceeded. This was presumably due to a validity checking algorithm of the system to discount extreme AoA beyond which an airliner would never conceivably achieve in its lifetime whilst airborne. Although in their case, that AoA was actually correct and the aural stall warning should never have ceased. As AoA probes become increasingly inaccurate beyond certain angles, some manufacturer s choose to temporarily derive AoA from other sources such as inertials.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastActivityDate="2015-04-07T00:45:08.623" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13887" PostTypeId="2" ParentId="13879" CreationDate="2015-04-07T00:48:55.363" Score="9" Body="&lt;p&gt;Aircraft selection for a particular route is quite complex, especially for a large airline that operates many different types of aircraft.  You're correct: generally speaking widebody aircraft are used for longer flights, but there are a number of other factors at play.  Some of these could be that a route has a very high peak demand, where a lot of people want to go from A-&gt;B at a given time.  LHR to Edinburgh seems particularly likely to be one of these city pairs.  Sydney to Melbourne is another one, and is only about 400 miles if my memory serves.  In both of these cases there is a dominant national airline in the mix (BA, Qantas) whereas in the USA there are almost always 3 or more large airlines operating any heavy route (New York to Boston, or Washington DC to Chicago, etc).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft scheduling also plays a role.  For example, the 767 in question might be scheduled to fly from Heathrow to Edinburgh and back in the morning, before picking up a long-haul flight to the USA in the afternoon.  If there's a 4 hour &quot;gap&quot; in the schedule for that particular aircraft, it might make more sense for the airline to run it as a short out-and-back rather than have it sit on the ground at LHR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, Heathrow is notoriously busy, and getting a takeoff/landing slot there is extremely expensive.  The high landing fees are charged at least partially regardless of the size of the aircraft, so there is some economic motivation here to divide those fixed costs by a larger number of passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As another data point, I checked the daily schedule between Haneda (the main domestic airport in Tokyo) and Hiroshima (~400 miles away) and found the following list of flights:  9x 737, 4x 787, 2x 767, 2x 777 - so in this case you have almost half the flights on widebody aircraft, and probably closer to 75% of the total seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also entirely possible (I haven't checked the schedules) that this 767 run is temporary, due to a period of peak demand or at a point in the year where the demands on that aircraft type are lower elsewhere in the route structure.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in summary: it's very hard to know all the reasons that a flight might be operated with a specific type.  You need to know a fair bit about the economics of the city pair, the fleet makeup of the airlines, the likely competition for the route, how the route timing interacts with other flights, the congestion level of the airport, and a lot of other things.  &lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-04-07T00:48:55.363" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13888" PostTypeId="2" ParentId="13885" CreationDate="2015-04-07T00:53:18.667" Score="2" Body="&lt;p&gt;You may want to take a look at &lt;a href=&quot;http://en.wikipedia.org/wiki/Supersonic_airfoils&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Delta_wing&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; but generally it has to do with the fact that many things change at super sonic speeds mainly &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The primary advantage of the delta wing is that, with a large enough&#xA;  angle of rearward sweep, the wing’s leading edge will not contact the&#xA;  shock wave boundary formed at the nose of the fuselage as the speed of&#xA;  the aircraft approaches and exceeds transonic to supersonic speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-07T00:53:18.667" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13889" PostTypeId="2" ParentId="13843" CreationDate="2015-04-07T00:57:23.803" Score="4" Body="&lt;p&gt;Large airlines have standing, negotiated contracts with major airports to buy fuel (and almost always also other services like cleaning, catering, etc).  Some times these are fixed-price contracts, sometimes they float in relationship to the spot price of jet fuel, sometimes they are a hybrid.  You can think of these as any other complex financial relationships: almost any way you can imagine a contract to be drawn up, someone has likely tried it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines' operations desks also constantly monitor the price of fuel at different airports and different times - and in some cases airplanes carry enough fuel to make a return trip without refueling because it ends up being cheaper to carry the fuel rather than purchase it at the next stop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For general aviation, the airport FBO (fixed base operation) generally has one and sometimes multiple fuel vendors on-site, that generally sell at a fixed price -- very much like a gas station for cars.  Obviously, airports that have more than one fuel vendor generally have more competitive prices, but even for single-vendor operations they can't make the fuel costs TOO high, or pilots will purchase just enough fuel to take off and go somewhere that gas is cheaper.  &lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-04-07T00:57:23.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13890" PostTypeId="2" ParentId="13885" CreationDate="2015-04-07T01:21:12.703" Score="9" Body="&lt;p&gt;Another reason to have shorter wings on high-speed or maneuverable aircraft deals with the aircraft's &lt;a href=&quot;http://en.wikipedia.org/wiki/Aspect_ratio_%28aerodynamics%29&quot; rel=&quot;noreferrer&quot;&gt;aspect ratio&lt;/a&gt;, which is the ratio between its length to is breadth/chord. Longer wings (high aspect) bend more under load, and may twist, which causes structural issues. Additionally, aircraft with shorter wings (low aspect) can roll much quicker. This means that a fighter jet with short wings may roll at rates up to 720 degrees/second while a large airliner or cargo plane may roll at 15-60 degrees per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A third reason is parasitic drag. From the linked wikipedia article above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While high aspect wings create less induced drag, they have greater parasitic drag, (drag due to shape, frontal area, and surface friction). This is because, for an equal wing area, the average chord (length in the direction of wind travel over the wing) is smaller. Due to the effects of Reynolds number, the value of the section drag coefficient is an inverse logarithmic function of the characteristic length of the surface, which means that, even if two wings of the same area are flying at equal speeds and equal angles of attack, the section drag coefficient is slightly higher on the wing with the smaller chord. However, this variation is very small when compared to the variation in induced drag with changing wingspan.&#xA;  For example, the section drag coefficient $c_d$; of a NACA 23012 airfoil (at typical lift coefficients) is inversely proportional to chord length to the power 0.129:&#xA;   $$ c_d \varpropto \frac{1}{(\text{chord})^{0.129}}.$$&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since parasite drag increases with airspeed, and high aspect wings have higher parasite drag, it makes sense for high-speed aircraft to have the wing that creates less drag at high speeds, and the slower aircraft to have the wing that creates less induced drag. You can see this in a simple graphic of the drag curves:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nXxFG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Since the induced drag is lower at high speeds anyway, there is little point in minimizing that, rather minimize the type of drag that is a much larger factor at high speeds)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="774" LastActivityDate="2015-04-07T01:21:12.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13891" PostTypeId="1" CreationDate="2015-04-07T03:11:55.580" Score="3" ViewCount="683" Body="&lt;p&gt;I own a small &lt;a href=&quot;http://en.wikipedia.org/wiki/Maintenance,_repair,_and_operations&quot; rel=&quot;nofollow&quot;&gt;maintenance, repair, and operations (MRO)&lt;/a&gt; shop in Indonesia. We are having trouble with our customers that required us to obtain FAA approval in order to get order from them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I already tried to ask the Indonesian regulator to help us to obtain FAA approval, but no luck. FAA requires an MRO to maintain at least one N-registered aircraft, and we don't have any in here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have same experience? And how can we proceed?&lt;/p&gt;&#xA;" OwnerUserId="8032" LastEditorUserId="1467" LastEditDate="2015-04-07T14:09:57.470" LastActivityDate="2015-06-09T17:17:24.863" Title="How can an international MRO apply for FAA approval?" Tags="&lt;aircraft-maintenance&gt;&lt;faa-approval&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13892" PostTypeId="2" ParentId="13891" CreationDate="2015-04-07T03:19:55.943" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/repair/become/forms/&quot; rel=&quot;nofollow&quot;&gt;These&lt;/a&gt; &lt;em&gt;14 CFR Part 145 Forms&lt;/em&gt; might be the forms you are looking for however there may be other forms for applying from overseas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/repair/&quot; rel=&quot;nofollow&quot;&gt;This&lt;/a&gt; site (FAA Aircraft Repair Stations Homepage) has some good links and &lt;a href=&quot;https://www.faa.gov/aircraft/repair/become/preapplication/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; are the pre application regulations you need to comply with. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d4441a9abc28fb63c4aead954102f6d7&amp;amp;node=14:3.0.1.2.19&amp;amp;rgn=div5&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; is the letter of the law of the FAA regulations (Starts at &lt;em&gt;Title 14 Section 145.1&lt;/em&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am no lawyer and cant really comment on this but I have no idea how FAA regulations work outside of the country and how/what foreign entities must comply with. I would advise contacting a local lawyer as well as a US lawyer about this. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-04-07T14:07:17.440" LastActivityDate="2015-04-07T14:07:17.440" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13894" PostTypeId="2" ParentId="13876" CreationDate="2015-04-07T08:17:16.017" Score="6" Body="&lt;p&gt;I will try to explain the physical mechanism, adding extra information compared to previous answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned before, the vortex generator is usually taking the shape of a plate. What this plate is doing is generating an small vortex. This vortex is basically a region where the flow is rotating around its axis. Basically this plate extracts energy from the flow generating this rotation on the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, this rotational flow has got energy and, if properly oriented interacts with the boundary layer over the wing providing further energy to it. With that extra energy the boundary layer is more resistant to separation, that means, that you can increase the angle of attack further and obtain a higher lift coefficient for the same wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now comes the why?. A vortex generator is always creating drag, always but it might reduce the fuel consumption of the airplane. How?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think about overall design of the airplane, for a given flying condition the amount of lift generated can be obtained big lift coefficient times wing surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine now, that we are designing the airplane and we have found that the condition that is dimensioning the needed size of the wing is, for example, the maximum runway length at take off, in order to reduce it you need to generate more lift at an specific speed. For being able to accomplish that you can either increase the wing surface or increase the maximum lift you can obtain from the wing, and you can accomplish that by introducing vortex generators smartly designed for that condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A trade off is later on made between increasing the wing surface (with the impact in drag and weight) and including the vortex generators. So, although adding those vortex generators are adding drag compared to a clean wing, it might be the case that you are actually reducing fuel consumption because the other alternative is adding more wing surface and the optimum solution became the vortex generators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several location of vortex generators, some of the on the vertical plane improving rudder efficiency, others in the upper surface of the wing, others over the engine affecting the slat during take-off or landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another use of vortex is after designing the airplane as quick fix to solve “unexpected issues”. &lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-04-07T08:17:16.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13895" PostTypeId="1" AcceptedAnswerId="13896" CreationDate="2015-04-07T08:41:06.967" Score="29" ViewCount="6764" Body="&lt;p&gt;Just saw a video in a news, a military cargo plane carrying people stranded in some country. The seats were like in a commercial airliner. This led me to ask the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be possible to see some examples where it was done, along with the procedure?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1467" LastEditDate="2015-04-07T08:47:02.880" LastActivityDate="2019-01-14T19:01:11.633" Title="Can a commercial cargo aircraft be converted into a commercial passenger aircraft, and vice versa?" Tags="&lt;cabin-design&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13896" PostTypeId="2" ParentId="13895" CreationDate="2015-04-07T08:50:57.467" Score="45" Body="&lt;p&gt;There are such a thing as &quot;Quick Change&quot; aircraft, allowing entire 'pallets' of chairs to be exchanged for cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://p9.storage.canalblog.com/98/38/1093714/95987903_o.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://p9.storage.canalblog.com/98/38/1093714/95987903_o.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;sup&gt;Image courtesy of canalblog.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K10jX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K10jX.jpg&quot; alt=&quot;qc&quot;&gt;&lt;/a&gt;&lt;sup&gt;Image courtesy of airliner.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=N3zb3Re4sjc&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nice film&lt;/a&gt; to show the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military transport aircraft can also be fitted out with stretchers or seats, or whatever other combo of stuff you want. To the best of my understanding these lock in like any other cargo pallet in the floor. They are less concerned with aesthetics and more with practicality:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6a/Defense.gov_News_Photo_111218-F-MJ260-913_-_U.S._Air_Force_airmen_prepare_to_take-off_on_a_C-17_Globemaster_III_cargo_aircraft_at_Ali_Air_Base_Iraq_signaling_the_end_of_Operation_New_Dawn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6a/Defense.gov_News_Photo_111218-F-MJ260-913_-_U.S._Air_Force_airmen_prepare_to_take-off_on_a_C-17_Globemaster_III_cargo_aircraft_at_Ali_Air_Base_Iraq_signaling_the_end_of_Operation_New_Dawn.jpg&quot; alt=&quot;military&quot;&gt;&lt;/a&gt;&lt;sup&gt;Image courtesy the DOD via Wikimedia&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bQrNX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bQrNX.jpg&quot; alt=&quot;seats&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Image courtesy of aarcorp.com&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-14T19:01:11.633" LastActivityDate="2019-01-14T19:01:11.633" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="13897" PostTypeId="2" ParentId="13895" CreationDate="2015-04-07T10:43:11.953" Score="25" Body="&lt;p&gt;It applies to helicopters too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When on holiday in the West Indies, one of the locations offered helicopter rides.  If anyone booked one, they contacted the local freight helicopter company who put the seats back into the helicopter, then they flew you round the bay, then took the seats out again to continue their bread-and-butter freight work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot told us helicopters come with seats, they took them out and put them in the shed.  They formed the company to shift building materials to construction sites.  One day a man approached them and asked if they could do sight-seeing rides for tourists.  They checked the seats were still in the shed and said &quot;of course&quot;.&lt;/p&gt;&#xA;" OwnerUserId="8035" LastEditorUserId="3386" LastEditDate="2015-04-07T10:52:31.893" LastActivityDate="2015-04-07T10:52:31.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13898" PostTypeId="2" ParentId="13878" CreationDate="2015-04-07T12:32:08.440" Score="9" Body="&lt;p&gt;This is by no means specific to aviation charts. Most likely it's simply general property of local maps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maps are flat, but earth surface is (approximately) spherical. So to represent ground features on the flat map a &lt;a href=&quot;http://en.wikipedia.org/wiki/Map_projection&quot;&gt;projection&lt;/a&gt; is needed and this projection can't preserve all relations—angles, distances and areas—precisely. So there are &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_map_projections&quot;&gt;many different projections&lt;/a&gt; that distort different properties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small area maps are usually drawn in &lt;a href=&quot;http://en.wikipedia.org/wiki/Map_projection#Azimuthal_.28projections_onto_a_plane.29&quot;&gt;azimuthal&lt;/a&gt; projection with the central point in the centre (or significant point near the centre) of the mapped area. While such projection does not preserve exactly any properties out of the centre, the distortion grows with distance from the centre, so for small areas it's appropriate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This however means, that &lt;em&gt;each section uses different projection&lt;/em&gt; and that near the edges the maps will be distorted each in a slightly different way. That's why the maps can't be &lt;em&gt;easily&lt;/em&gt; laid out to form a bigger map. You would have to lay them out on a sphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could try using some software for stitching panoramatic photos (&lt;a href=&quot;http://hugin.sourceforge.net/&quot;&gt;here&lt;/a&gt; is one such you can use for free). That should be able to apply suitable transformation to make the maps match. At the cost of increasing the distortion.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-04-07T12:32:08.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13899" PostTypeId="1" AcceptedAnswerId="13900" CreationDate="2015-04-07T13:25:09.893" Score="7" ViewCount="3123" Body="&lt;p&gt;Reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/13895/can-a-commercial-cargo-aircraft-be-converted-into-a-commercial-passenger-aircraf&quot;&gt;this question&lt;/a&gt; I saw this picture in MikeFoxtrot's answer and noticed how easier it would be to board the plane using that huge door:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OmOmt.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that for single aisle planes you wold need to form a single line anyway, but for two aisle planes having a wide door could speed up the boarding process a lot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is there a reason why it is not done? What is the limiting factor in the door size?&lt;/p&gt;&#xA;" OwnerUserId="7417" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-04-08T06:04:03.253" Title="Why don't big airliners have bigger doors?" Tags="&lt;aircraft-design&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13900" PostTypeId="2" ParentId="13899" CreationDate="2015-04-07T13:46:32.617" Score="11" Body="&lt;p&gt;Multi-aisle commercial aircraft adopt a multi-door boarding strategy rather than a single-huge door (see the A380 or the B747, both use two doors). This helps under the structural viewpoint: the presence of a door (cargo or passenger that might be) induces design problems that are amplified if the compartment has to be pressurised.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A door interrupts both &lt;a href=&quot;http://en.wikipedia.org/wiki/Fuselage#Semi-monocoque&quot;&gt;frames&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Longeron&quot;&gt;stringers&lt;/a&gt; and weakens the overall aircraft structure. A huge door interrupts many more frames than a small one and two small ones can be set apart from each other to have some continuous frames between the two, restoring some rigidity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The complex closure systems ensure that part of the stresses are carried by the door material, but it will never be perfectly transmitted as it would be without a door. As mentioned before, the stresses are heightened if the compartment is pressurised (as when passengers have to be transported).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1696" LastEditDate="2015-04-07T14:41:11.317" LastActivityDate="2015-04-07T14:41:11.317" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13901" PostTypeId="2" ParentId="13899" CreationDate="2015-04-07T14:48:46.077" Score="8" Body="&lt;p&gt;Before answering your question, please take a look at the excellent &lt;a href=&quot;https://aviation.stackexchange.com/a/12311/65&quot;&gt;answer to &lt;em&gt;Why aren't planes loaded from both ends?&lt;/em&gt;&lt;/a&gt;, which talks about increasing efficiency in boarding passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners do not need bigger doors for boarding people because people are not like big crates which are loaded into airplanes using forklifts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To incorporate a wider door, we need to do the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;have a bigger &lt;em&gt;foyer&lt;/em&gt; inside the door&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All space on a passenger airplane is fully utilized to the maximum extent. Having a large area just to greet passengers and help them to their seats is not a very efficient use of that space.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;size of jet bridge&lt;/p&gt;&#xA;&#xA;&lt;p&gt;New jet bridges will be needed, which can allow more than two people walk side-by-side.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;gate procedures&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the airlines have designated their seats into &lt;a href=&quot;http://www.seatguru.com/articles/boarding_procedures.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;zones&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt;. When boarding, people are called in a manner which expedites the boarding process. With a bigger door, this process needs to be adjusted for boarding more people at the same time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At present, only A380 has an upper deck for passengers, which extends the length of the aircraft. They already have multiple jet bridges to maximize the boarding process:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9ULZ4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9ULZ4.jpg&quot; alt=&quot;A380 Jet Bridge&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.flysfo.com/sites/default/content-images/about/newsletter/emiratesA380.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Image Source&lt;/em&gt;&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: Not talking about &lt;a href=&quot;http://en.wikipedia.org/wiki/Travel_class&quot; rel=&quot;nofollow noreferrer&quot;&gt;travel classes&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-04-07T14:48:46.077" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13903" PostTypeId="2" ParentId="13882" CreationDate="2015-04-07T15:14:40.503" Score="16" Body="&lt;p&gt;The FAA's &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; gives both US and ICAO definitions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;RADAR CONTACT&lt;/em&gt;&lt;/strong&gt;- a. Used by ATC to inform an aircraft that it is identified on the radar display and radar flight following will be&#xA;  provided until radar identification is terminated. Radar service may&#xA;  also be provided within the limits of necessity and capability. When a&#xA;  pilot is informed of “radar contact,” he/she automatically&#xA;  discontinues reporting over compulsory reporting points. [...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. The term used to inform the controller that the aircraft is&#xA;  identified and approval is granted for the aircraft to enter the&#xA;  receiving controllers airspace. (See ICAO term RADAR CONTACT.)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;RADAR CONTACT [ICAO]- The situation which exists when the radar blip&#xA;  or radar position symbol of a particular aircraft is seen and&#xA;  identified on a radar display.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;RADAR CONTACT LOST&lt;/em&gt;&lt;/strong&gt;- Used by ATC to inform a pilot that radar data used to determine the aircraft’s position is no longer being&#xA;  received, or is no longer reliable and radar service is no longer&#xA;  being provided. The loss may be attributed to several factors&#xA;  including the aircraft merging with weather or ground clutter, the&#xA;  aircraft operating below radar line of sight coverage, the aircraft&#xA;  entering an area of poor radar return, failure of the aircraft&#xA;  transponder, or failure of the ground radar equipment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that this is not a universal term, Canada uses &quot;radar identified&quot; instead. Their equivalent of the P/CG is the &lt;a href=&quot;http://www.tc.gc.ca/en/services/aviation/reference-centre/advisory-circulars/ac-100-001.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Glossary for Pilots and Air Traffic Services Personnel&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“Radar identified”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An expression used by ATC to inform the pilot of an aircraft when radar identification is established.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Fr: « Identifié radar »&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;“Radar contact”&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;U.S.: Expression for: “Radar identified”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-06-14T17:23:30.190" LastActivityDate="2018-06-14T17:23:30.190" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="13904" PostTypeId="1" CreationDate="2015-04-07T16:03:36.460" Score="14" ViewCount="2195" Body="&lt;p&gt;In the case of a  flame-out in both engines on the two-engine A320, does the aircraft revert to &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_control_modes#Flight_control_laws_.28Airbus.29&quot;&gt;Direct law or does it maintain Normal Law&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example is &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;US Airways 1549&lt;/a&gt; (the landing on the Hudson).&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="65" LastEditDate="2015-04-07T16:12:23.153" LastActivityDate="2019-03-22T21:19:23.343" Title="Does an A320 revert to Direct Law if both engines flame out?" Tags="&lt;engine-failure&gt;&lt;airbus-a320&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13905" PostTypeId="2" ParentId="13904" CreationDate="2015-04-07T16:34:09.593" Score="21" Body="&lt;p&gt;The airplane will no longer be in normal law mode if both engines fail and no other electrical generator is online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane needs a primary source of electrical power in order to remain in normal law (among other things of course). If both engines lose power, then the generators on those engines also lose power. The only other primary electrical source is the APU generator. In addition to the batteries, the RAT (ram air turbine) is also available to supply electric power (along with hydraulic power) in an emergency situation. In this mode, the flight controls &lt;a href=&quot;http://ads-b.ca/a320/A319-320-321_Flight_Deck_and_Systems_Briefing_for_Pilots.pdf&quot;&gt;reconfigure to alternate law&lt;/a&gt; until a generator is brought back online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf&quot;&gt;US Airways 1549 report&lt;/a&gt;, page 88:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the captain started the APU, which improved the outcome of the ditching by ensuring that a primary source of electrical power was available to the airplane and that the airplane remained in normal law and maintained the flight envelope protections&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-07T23:28:10.943" LastActivityDate="2015-04-07T23:28:10.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13907" PostTypeId="1" CreationDate="2015-04-07T20:05:25.903" Score="3" ViewCount="682" Body="&lt;p&gt;I recently got the &lt;a href=&quot;http://en.wikipedia.org/wiki/Polar_curve_(aerodynamics)&quot; rel=&quot;nofollow&quot;&gt;polar curve&lt;/a&gt; of an aircraft with the method of Anderson. But this method is too old.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does someone know a recent method for the polar curve without using &lt;a href=&quot;http://en.wikipedia.org/wiki/Computational_fluid_dynamics&quot; rel=&quot;nofollow&quot;&gt;CFD&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="8044" LastEditorUserId="65" LastEditDate="2015-04-07T20:13:41.803" LastActivityDate="2015-04-09T19:17:11.803" Title="How can I calculate polar curve?" Tags="&lt;aerodynamics&gt;&lt;polar&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13908" PostTypeId="1" AcceptedAnswerId="13911" CreationDate="2015-04-07T20:32:09.923" Score="8" ViewCount="2794" Body="&lt;p&gt;I wonder if the arresting wires would work the 'other' way?&lt;/p&gt;&#xA;" OwnerUserId="8046" LastActivityDate="2021-01-12T04:23:33.957" Title="Is landing the 'wrong way' possible on an aircraft carrier?" Tags="&lt;landing&gt;&lt;aircraft-carrier&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13910" PostTypeId="2" ParentId="13878" CreationDate="2015-04-07T21:04:43.777" Score="5" Body="&lt;p&gt;The FAA's &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/media/FAA_Sect_US.jpg&quot; rel=&quot;noreferrer&quot;&gt;graphical index of sectional charts&lt;/a&gt;&#xA;shows all the charts for the coterminous 48 states laid out on a single&#xA;map projection, but the areas covered by the charts do not all align&#xA;with the rectangular boundaries of that projection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were to obtain copies of all the charts and attempt to lay them&#xA;out according to that projection, you would have to rotate the western&#xA;charts clockwise and the eastern charts counterclockwise.&#xA;Any two contiguous charts might or might not be rotated at the same angle;&#xA;charts directly north or south of each other (several pairs along the&#xA;northern edge of the 48 states) might be aligned, but other pairs of charts&#xA;that have an east-west offset (most of the other adjacent pairs)&#xA;are likely to be rotated at a different angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So even if the charts are truly drawn to the same projection&#xA;and are perfectly executed, you will not be able to align them perfectly&#xA;just by moving them up, down, left, or right. &#xA;You will need some rotation as well.&lt;/p&gt;&#xA;" OwnerUserId="3831" LastActivityDate="2015-04-07T21:04:43.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13911" PostTypeId="2" ParentId="13908" CreationDate="2015-04-07T23:57:41.727" Score="17" Body="&lt;p&gt;You're going to run into a few issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a diagram of a typical aircraft carrier layout. Normally aircraft would land from right to left. The four cables are located closer to the right end than the left. The extra length after the cables is both to allow a &quot;bolter&quot; (&lt;a href=&quot;https://youtu.be/unjQOOxS-5k&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;) time to accelerate in case of missing the arresting hook; and to allow an aircraft that caught a cable time to decelerate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice how far an aircraft can continue down the deck (&lt;a href=&quot;https://youtu.be/cOr5dbq916s?t=1m35s&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;) after catching the cable. Even if you catch the first cable, you might go off the aft end of the ship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wHaAl.jpg&quot; alt=&quot;Flight Deck Diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue is the way that the arrestor cables work. The housing where the cable enters the flight deck is curved to allow the landing aircraft to pull on the cable as it decelerates. The cable is not designed to be pulled in the opposite direction, which could cause it to break (&lt;a href=&quot;https://youtu.be/nYXbFJrA4Ik&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/awrAv.jpg&quot; alt=&quot;Arrestor Gear and F-18 Landing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from these issues, you would also lack the &lt;a href=&quot;https://en.wikipedia.org/wiki/Optical_landing_system&quot; rel=&quot;noreferrer&quot;&gt;FLOLS&lt;/a&gt; system that provides physical guidance during the landing. And as &lt;a href=&quot;https://aviation.stackexchange.com/questions/13908/is-landing-the-wrong-way-possible-on-an-aircraft-carrier#comment31147_13908&quot;&gt;voretaq7 also mentioned&lt;/a&gt;, you have to either touch down late, or catch the cable late, both of which could pose problems.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-04-08T01:15:04.517" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13912" PostTypeId="1" CreationDate="2015-04-08T01:34:55.730" Score="12" ViewCount="4655" Body="&lt;p&gt;When landing at a normal ground airport, the runway facing the compass point nearest to the heading of the wind is always operated, so that aircraft landing and taking off alway have to use the least distance of runway as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an aircraft carrier the whole ship can rotate; so do they typically always face into the wind? How often do they rotate the ship if this is the case?&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2015-04-08T20:39:49.073" Title="Do aircraft carriers always face into the wind?" Tags="&lt;wind&gt;&lt;aircraft-carrier&gt;&lt;heading&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13913" PostTypeId="2" ParentId="13912" CreationDate="2015-04-08T02:27:09.800" Score="14" Body="&lt;p&gt;During flight operations, the aircraft carrier strives to maintain 30 knots of wind down the angle of the flight deck.  Generally speaking, the carrier will adjust its speed and course through the ocean to maintain the desired winds.  However, shifting winds and the sheer magnitude of the carrier may mean that the winds are generally down the angle, but may involve a crosswind component.  Also, the structure of the carrier, because of its enormous size, actually influences the flow of the wind, and can create pockets of low pressure in the approach where high sink rates can develop.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-04-08T05:03:06.030" LastActivityDate="2015-04-08T05:03:06.030" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13916" PostTypeId="2" ParentId="13899" CreationDate="2015-04-08T06:04:03.253" Score="4" Body="&lt;p&gt;A door involves reinforcement of the structure around it (on the fuselage), so a bigger door involves more structural reinforcement, which means it adds more weight (because of the beefier structural reinforcement). In airplane, whatever you do, you want to keep the weight of the structure as low as possible, so you can carry more people. It's economic reason (the airline is a business). Technically windows need structural reinforcement as well, but without window it would be boring, and probably less people would fly (they would feel less safe to not see outside).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin is pressurized, so the bigger the door, the more pressure pushing to pop it open (which is why it would need beefier structural reinforcement)&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T06:04:03.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13917" PostTypeId="2" ParentId="13885" CreationDate="2015-04-08T06:07:51.800" Score="1" Body="&lt;p&gt;Short wing means less structural weight. But an airplane needs an optimum wing surface area (optimum for its weight, in other words the wing it needs to generate enough lift for the size of the airplane). So for the same lift, a shorter wing would be lighter, &lt;em&gt;but&lt;/em&gt; study have shown that lift is not generated on the full span of the wing, so a short wing would not be efficient. A longer wing is much more efficient (generate more lift for its surface) but at the expense of weight (you need a beefier structure to maintain the integrity of the wing, so there is a sweet spot in between)&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T06:07:51.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13918" PostTypeId="2" ParentId="13600" CreationDate="2015-04-08T06:13:13.937" Score="-4" Body="&lt;p&gt;If it pokes a hole, the pressure in the cabin will be lost (which involve possible injury to the ear drums or death of the people inside, as at cruise altitude there is not enough oxygen in the air for the human body, which is why it is pressurized inside and maintained at near sea level pressure).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft can be damaged to the point of losing a structural panel, but not necessarily crashing. Unless the pilot falls unconscious due to the lack of oxygen. (Oxygen mask only have about 15 minute of oxygen by the way).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the bullet hits an engine, or poke the wing (i.e. fuel tank), then there is high risk of explosion, with dramatic consequences.&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T06:13:13.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13919" PostTypeId="1" AcceptedAnswerId="13941" CreationDate="2015-04-08T06:16:04.647" Score="24" ViewCount="6576" Body="&lt;p&gt;I am taking my mom for a trip over the grand canyon. My mom lives at sea level, whereas I live at 5000ft, and workout at 8000ft daily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The VFR lowest route over the Grand Canyon is 11,500ft MSL. If I am flying over this with my mother and she starts to exhibit signs of hypoxia, what are my options?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the law to remain at the prescribed altitudes and headings while flying around the Grand Canyon. That being said, obviously passenger safety comes before anything else. If my mom gets sick, I would have to drop in altitude, but what kind of consequences would I face for this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of hypoxia in one of these corridors, what would be the best way to deviate while remaining safe and courteous?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="62" LastEditDate="2015-04-09T13:19:14.940" LastActivityDate="2015-04-09T13:19:14.940" Title="How should I deal with a passenger experiencing hypoxia over the Grand Canyon?" Tags="&lt;faa-regulations&gt;&lt;emergency&gt;&lt;medical&gt;&lt;hypoxia&gt;&lt;high-altitude&gt;" AnswerCount="4" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13920" PostTypeId="2" ParentId="13837" CreationDate="2015-04-08T06:18:39.690" Score="0" Body="&lt;p&gt;A propeller has a bigger diameter than a fan, and because of that, the structure of the blade on a propeller sustain more 'g' (more centrifuge force if you will) so the blade of a propeller will eventually explode if it rotates to fast, because there is more mass away from the center of rotation, it 'pulls' everything outside. It's rotational inertia. (and you need a big propeller diameter because it needs to provide enough push for the airplane to fly).&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T06:18:39.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13923" PostTypeId="2" ParentId="13919" CreationDate="2015-04-08T08:35:33.157" Score="20" Body="&lt;p&gt;You don't have to divert, in fact it may be a bad option depending on conditions (I would recommend you don't go if conditions will make diverting dicey though). You can treat the hypoxia with low cost bottled oxygen supplies &lt;a href=&quot;http://www.pilotmall.com/product/Boost-Oxygen-22oz-Bottle/oxygen-systems&quot;&gt;specifically made for this situation&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 11,000ft it's unlikely lack of oxygen will make your mother really ill, a top of oxygen is all she's likely to need. A pony bottle should let you get through your flight if she exhibits some symptoms, at 12 bucks a pop you can buy 2 just in case. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="65" LastEditDate="2015-04-08T13:48:22.930" LastActivityDate="2015-04-08T13:48:22.930" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13924" PostTypeId="2" ParentId="1630" CreationDate="2015-04-08T09:28:06.633" Score="1" Body="&lt;p&gt;Time for a 360 turn at 30 degree bank angle is TAS/60:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;120 knots   2 minutes&#xA;180 knots   3 minutes&#xA;210 knots   3.5 minutes (airliner, clean)&#xA;240 knots   4 minutes (&quot;heavy&quot; airliner clean)&#xA;480 knots   8 minutes (airliner in the cruise at altitude)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Times will be slightly longer at 25 degrees.  You can't fly a rate one turn in a commercial aircraft these days.&lt;/p&gt;&#xA;" OwnerUserId="8052" LastActivityDate="2015-04-08T09:28:06.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13926" PostTypeId="1" CreationDate="2015-04-08T10:37:56.483" Score="6" ViewCount="1733" Body="&lt;p&gt;Because, it might lead to reverse flow of air and could stall the plane. Is there some mechanism to prevent this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a &lt;a href=&quot;http://en.wikipedia.org/wiki/Manx2_Flight_7100&quot; rel=&quot;noreferrer&quot;&gt;crash in Ireland a few years ago&lt;/a&gt;, when the pilot of a small charter plane accidentally put one of the turboprop's in reverse.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="65" LastEditDate="2015-04-08T13:57:24.683" LastActivityDate="2015-04-08T13:57:24.683" Title="In turboprops, is there a mechanism to prevent the blades running in opposite direction?" Tags="&lt;accidents&gt;&lt;propeller&gt;&lt;turboprop&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13927" PostTypeId="1" AcceptedAnswerId="15083" CreationDate="2015-04-08T10:47:56.817" Score="6" ViewCount="815" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iqJXh.jpg&quot; alt=&quot;enter image description here&quot;&gt;What kind of information is displayed by the ground surveillance radar scope on Advanced Surface Movement Guidance and Control Systems (A-SMGCS) or similar systems like &lt;a href=&quot;https://www.faa.gov/air_traffic/technology/asde-x/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASDE-X&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="8056" LastEditorUserId="8056" LastEditDate="2015-04-08T20:14:53.987" LastActivityDate="2015-05-26T10:53:05.020" Title="What kind of information is shown on airport surface traffic surveillance displays?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="13928" PostTypeId="2" ParentId="13926" CreationDate="2015-04-08T11:34:19.213" Score="8" Body="&lt;p&gt;Most manufacturers realise this is a serious risk so most are 'gated' in that you have to do something to get them into this range. This is like pulling up the reverse tabs on the throttle levers on the B737 or A320 that is only possible when they are in the idle position.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;ATR 42/75&lt;/strong&gt;: Has something called Idle Gate that prevents throttles from going back too far when engaged.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Dash 8&lt;/strong&gt;: Has gated throttles that requires pulling up a pin to get them into reverse.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is to the best of my knowledge nothing (in general at least) to stop to the thrust from being 'reversed', or more specifically to angle to blades to what is known as the 'beta' range, if you are intent on doing it. Unlike jets where doors open for instance and the process is a little more complex, this is just rotating the blade below a certain angle.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I found the &lt;a href=&quot;http://www.aaiu.ie/sites/default/files/report-attachments/REPORT%202014-001_0.pdf&quot; rel=&quot;noreferrer&quot;&gt;accident report&lt;/a&gt; [PDF] for the Manx2 flight. There were multiple things going on here rather than a single cause:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Generally bad piloting for putting them in a late go-around situation to start with.&lt;/li&gt;&#xA;&lt;li&gt;There were errors in the engine, causing a thrust mismatch.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lEaZm.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/rhEce.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;&lt;li&gt;This meant that one engine proceeded to continue into negative thrust.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/M5Okm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It does then not come as a complete surprise that you manage to flip the plane over from considerable unsymmetric thrust when you are close to stall speed.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-04-08T12:46:06.127" LastActivityDate="2015-04-08T12:46:06.127" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13930" PostTypeId="2" ParentId="13926" CreationDate="2015-04-08T13:48:01.100" Score="6" Body="&lt;p&gt;As was pointed out in a comment, the &quot;reverse thrust&quot; of the Beta range, which is used to slow the aircraft on landing and which certainly can do disastrous things if deployed inadvertently in-flight, is a matter of propeller angle and not the direction of rotation of the engine.  If it is running, the turbine engine is going to turn one way and that way only; all sorts of things wouldn't work right to try to run it turning it backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The place where a prop and engine might try to go backwards is with a shut-down engine and a feathered prop.  If the engine isn't running, then the lubricating oil that normally keeps moving parts lubricated and cool, isn't being supplied, and it's important that there NOT be any movement.  With the prop in the &quot;feather&quot; position, it's generating a slight force to turn the engine the &quot;wrong&quot; way, and on the system I'm familiar with, we had a &quot;prop brake&quot; that would hold the prop stationary at that point.  If you took the blade angle out of feather, then the brake would allow the propeller to turn the &quot;right&quot; way -- as in a restart attempt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to directly answer the question as asked, yes you can find turboprop engines with a system to prevent them from rotating the wrong way.  But the reason for this has to do with preventing unwanted (unlubricated) rotation after an in-flight shutdown, rather than anything related to reverse thrust.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-08T13:48:01.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13931" PostTypeId="2" ParentId="482" CreationDate="2015-04-08T14:21:26.587" Score="2" Body="&lt;p&gt;As mentioned, there are lots of procedures that can be used. The one I am most familiar with (from a GA standpoint) is &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Land-and-Hold-Short-Operations-LAHSO&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Land And Hold Short Operation (LAHSO)&lt;/strong&gt;&lt;/a&gt;. In this case, ATC may sequence you in on a runway and then ask you if you can preform a LAHSO (this happened to me last week actually).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic procedure is to land and stop the aircraft before the runway intersection, so that the other runway can remain in use since, in theory, you won't cross it. Keep in mind that this is dependent on the aircraft and airport in question considering the landing distances that are required.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the record, I was flying a Piper Warrior and landing at Northeast Philadelphia Airport (KPNE) on runway 33 (length: 5000 feet) and the intersection with 6/24 is far off at the other end making the maneuver quite easy.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-04-08T14:42:33.633" LastActivityDate="2015-04-08T14:42:33.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13932" PostTypeId="2" ParentId="13066" CreationDate="2015-04-08T14:50:27.903" Score="5" Body="&lt;p&gt;They use instruments instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BA flight 9 had it's windscreen rendered somewhat opaque by volcanic ash&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JJuQe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As Flight 9 approached Jakarta, the crew found it difficult to see anything through the windscreen, and made the approach almost entirely on instruments, despite reports of good visibility. The crew decided to fly the Instrument Landing System (ILS); however, the vertical guidance system was inoperative, so they were forced to fly with only the lateral guidance as the first officer monitored the airport's Distance Measuring Equipment (DME). He then called out how high they should be at each DME step along the final approach to the runway, creating a virtual glide slope for them to follow. It was, in Moody's words, &quot;a bit like negotiating one's way up a badger's arse.&quot; Although the runway lights could be made out through a small strip of the windscreen, the landing lights on the aircraft seemed to be inoperable. After landing, the flight crew found it impossible to taxi, due to glare from apron floodlights which made the already sandblasted windscreen opaque.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_9&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-04-08T14:50:27.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13933" PostTypeId="1" AcceptedAnswerId="13937" CreationDate="2015-04-08T14:53:51.707" Score="4" ViewCount="1158" Body="&lt;p&gt;I have a pilot license in Brazil and would like to purchase an aircraft in the US and then register it in my country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My license allows me to fly the aircraft back to my country?&lt;/p&gt;&#xA;" OwnerUserId="8058" LastEditorUserId="62" LastEditDate="2015-04-08T21:25:28.847" LastActivityDate="2015-04-09T17:27:31.890" Title="As a Brazilian pilot, can I buy an aircraft in the US then fly it to Brazil to register it?" Tags="&lt;faa-regulations&gt;&lt;international&gt;&lt;anac-regulations&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13934" PostTypeId="2" ParentId="13513" CreationDate="2015-04-08T16:02:12.013" Score="8" Body="&lt;p&gt;There isn't much non-flying duty for airline pilots. &#xA;The most important is recurrent training. Pilots are required to attend a refresher course at least annually. This school covers regulations, aircraft systems, and performance. The performance part involves computing weight and balance, airfield/weather restrictions, fuel required, etc (basically the same thing as a Cessna 172, but with much bigger numbers). Additionally, full flight simulators are used to teach and/or evaluate normal and non-normal (we don't get emergencies anymore) procedure. This training is usually concurrent with the groundschool.&#xA;Pilots are required to maintain their approach charts and aircraft manuals; changes come frequently.&#xA;A junior First Officer will spend an eternity (at least it seems like it) doing standby duty. This involves being available to take the place of any pilot who calls in sick or is otherwise unavailable.&#xA;All pilots must pass a flight physical. The implication is that they must maintain themselves in at least minimal health.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this at least partially answers your question.&lt;/p&gt;&#xA;" OwnerUserId="8016" LastEditorUserId="8016" LastEditDate="2015-04-08T16:24:22.170" LastActivityDate="2015-04-08T16:24:22.170" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13936" PostTypeId="2" ParentId="13851" CreationDate="2015-04-08T16:25:17.190" Score="3" Body="&lt;p&gt;To expand on &lt;a href=&quot;https://aviation.stackexchange.com/a/13852/1696&quot;&gt;the answer from raptortech97&lt;/a&gt;, taxiing an aircraft is similar to driving a car. Instead of traffic signals, the ground controller tells the pilot where to go, but the pilots should still be looking out the window and remain aware of aircraft around them. As with aircraft in the air, the ground controller will anticipate conflicts between aircraft and give them instructions to avoid issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A controller will instruct an aircraft when they need to yield to others:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...give way to company 737 on Delta.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And possibly advise the other aircraft as well:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...continue on Bravo, company will give way to you at Delta.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Often aircraft are going to the same place (like the active runway), so it can simplify things to just tell pilots to follow other airplanes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...follow the company 737 on Delta.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In conditions where aircraft will be taxiing, visibility is generally good enough that pilots can see other aircraft. If visibility gets worse, the ground controller will be more cautious, knowing that the aircraft may not be able to see each other.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-04-08T16:25:17.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13937" PostTypeId="2" ParentId="13933" CreationDate="2015-04-08T16:30:35.287" Score="5" Body="&lt;p&gt;I'm not sure if you're asking about general export regulations, in which case &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Aircraft-Ownership/Business-Justification/Importing-and-Exporting-Aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Farhan's link&lt;/a&gt; is useful, or the more specific licensing question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But regarding licensing it's clear that you may not fly a US aircraft from the US to Brazil with &lt;em&gt;only&lt;/em&gt; a Brazilian license. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_13&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.3&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;em&gt;Required pilot certificate for operating a civil aircraft of the&#xA;  United States&lt;/em&gt;. No person may serve as a required pilot flight&#xA;  crewmember of a civil aircraft of the United States, unless that&#xA;  person:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Has in the person's physical possession or readily accessible in&#xA;  the aircraft when exercising the privileges of that pilot certificate&#xA;  or authorization—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) A pilot certificate issued under this part and in accordance with&#xA;  §61.19;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) A special purpose pilot authorization issued under §61.77;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) A temporary certificate issued under §61.17;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) A document conveying temporary authority to exercise certificate&#xA;  privileges issued by the Airmen Certification Branch under §61.29(e);&#xA;  or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(v) When operating an aircraft within a foreign country, a pilot&#xA;  license issued by that country may be used.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, you can use your Brazilian license to fly a US aircraft &lt;em&gt;in Brazil&lt;/em&gt; (see 61.3(a)(1)(v) above) but otherwise you need a US license or a special authorization (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_177&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.77&lt;/a&gt; covers leasing and commercial operations so it almost certainly won't apply to you).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know very little about this, but at least in theory it looks like your options are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Get a US license yourself, perhaps a foreign-based license based on your Brazilian one (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_175&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.75&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Get some special permission from the FAA&lt;/li&gt;&#xA;&lt;li&gt;Pay a &lt;a href=&quot;https://aviation.stackexchange.com/questions/13646/how-are-ga-aircraft-ferried-from-factories&quot;&gt;ferry&lt;/a&gt; company to fly or transport the aircraft to Brazil&lt;/li&gt;&#xA;&lt;li&gt;Register the aircraft as Brazilian before it leaves the US (this may not even be possible)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And those are only the FAA/aviation issues, you have to think about customs and general import/export regulations too, both in the US and Brazil. I would look for some specialized help with this.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-04-09T12:42:25.657" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="13938" PostTypeId="1" CreationDate="2015-04-08T16:34:16.793" Score="4" ViewCount="1684" Body="&lt;p&gt;The Superbay is a maintenance hangar on the north end of the field at San Francisco International Airport, north of runway 28R and west of runway 19R. On the airport diagram it is not labeled, but next to fire station no. 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is currently used by United Airlines and American Airlines for maintenance. Ground control refers to it as the &quot;Superbay&quot; when giving instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When was the Superbay built? Did it have any uses before the current tenants? Where did the name come from?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="65" LastEditDate="2015-04-09T12:47:10.947" LastActivityDate="2015-04-09T12:47:45.820" Title="What is the history of the &quot;Superbay&quot; at San Fransisco International?" Tags="&lt;airport&gt;&lt;aviation-history&gt;&lt;sfo&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13939" PostTypeId="2" ParentId="13919" CreationDate="2015-04-08T17:16:40.643" Score="5" Body="&lt;p&gt;In principle at least, you can begin to experience hypoxia at 5000ft. By 10,000ft, it's affecting your eyesight, and probably starting to affect your judgement a little. At 15,000ft, your judgement can be measurably impaired, and you'll often experience euphoria, so you can't TRUST your judgement even if you think everything is okay.&lt;br&gt;&#xA;Your personal experience and thresholds may vary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.3.7.6&quot; rel=&quot;nofollow&quot;&gt;FAR 91.211&lt;/a&gt; spells out supplemental oxygen requirements. At 11,500, you're close enough to the FAR regs (12,500) that you really ought to be carrying supplemental oxygen. These regs are known to be very liberal. Bring some oxygen for both of you and no worries.&lt;/p&gt;&#xA;" OwnerUserId="6840" LastEditorUserId="64" LastEditDate="2015-04-08T17:59:19.790" LastActivityDate="2015-04-08T17:59:19.790" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13940" PostTypeId="2" ParentId="13938" CreationDate="2015-04-08T17:17:03.213" Score="4" Body="&lt;p&gt;Superbay Hangar is a maintenance facility at San Francisco Airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;About previous tenants and when it was built, &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/4144856&quot; rel=&quot;nofollow&quot;&gt;this forum mentions that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is the large aircraft hangar built by AA in the 1970's to house the&#xA;  747. Both AA and TWA were the first tenants. Now it's UAL and AA. UAL uses it as a line maintenance hangar for the wide-body fleet.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It sits all alone out towards the bay. When VIP's come to SFO, they&#xA;  park next to this hangar due to its isolated location.&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  The SuperBay was built and is owned by the City of San Francisco. It&#xA;  is primarily used by UA/AA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Going through the &lt;a href=&quot;http://www.flysfo.com/about-sfo/history-sfo&quot; rel=&quot;nofollow&quot;&gt;timeline on SFO's History&lt;/a&gt;, the vacant area of this hangar is visible in one of the pictures of 1960s. In later pictures (1981), it appears to be there (shown in the background)&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, more references are found about this hangar in the future development plans of the airport than the history. Examples can be seen &lt;a href=&quot;http://media.flysfo.com.s3.amazonaws.com/assets/downloads/reports/capitalplan_fy1314.pdf&quot; rel=&quot;nofollow&quot;&gt;here (PDF, p20 and 28)&lt;/a&gt; and &lt;a href=&quot;http://www.flysfo.com/sites/default/download/about/commission/agenda/pdf/minutes/m040213.pdf&quot; rel=&quot;nofollow&quot;&gt;here (PDF, p6)&lt;/a&gt;. This &lt;a href=&quot;http://www.schembri.com/html_gallery.cfm?menu_itemID=905264&amp;amp;load=html&amp;amp;parentID=903869&quot; rel=&quot;nofollow&quot;&gt;site also talks&lt;/a&gt; about some future work for Superbay Hangar.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: I am not 100% sure about direction of the camera, but it might be pointing towards that hangar.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-04-09T12:47:45.820" LastActivityDate="2015-04-09T12:47:45.820" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13941" PostTypeId="2" ParentId="13919" CreationDate="2015-04-08T17:56:53.737" Score="34" Body="&lt;p&gt;First, let's be crystal clear on something: A person experiencing symptoms of acute hypoxia &lt;strong&gt;&lt;em&gt;is an emergency&lt;/em&gt;&lt;/strong&gt; which requires immediate action to ensure the safety of that person. &lt;em&gt;In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule …  to the extent required to meet that emergency.&lt;/em&gt; (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.2&quot;&gt;FAR 91.3 (b)&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you're over the Grand Canyon at 11,500 feet and your mother starts showing signs of hypoxia you key the mic and let ATC know you have a passenger showing signs of hypoxia, tell them you are descending to a lower altitude, and ask for vectors to an airport where you can land. If they give you any trouble about it you respond with &quot;N12345 &lt;em&gt;is declaring a medical emergency&lt;/em&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All that said, there are sensible things you can do to mitigate the risk of hypoxia and avoid the need to declare an emergency.&lt;br&gt;&#xA;If you intend to spend an extended period of time at altitude (which I personally define as &quot;Over 10,000 feet&quot; for an average healthy non-smoker):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Bring a &lt;a href=&quot;http://www.skyox.com&quot;&gt;portable oxygen system&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;Ideally with enough cannulas/outlets for yourself and your mother/other passengers).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;If a full oxygen system isn't an option bring one or more &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/8543&quot;&gt;&quot;boost cans&quot;&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;These can provide temporary/limited relief for symptoms of hypoxia – probably enough to get yourself back on the ground, or at least to a lower altitude.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Carry a relatively inexpensive &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/6301&quot;&gt;pulse oximeter&lt;/a&gt;&lt;/strong&gt;&lt;br&gt;&#xA;Check your &lt;a href=&quot;http://en.wikipedia.org/wiki/Oxygen_saturation_(medicine)&quot;&gt;SpO&lt;sub&gt;2&lt;/sub&gt;&lt;/a&gt; periodically to catch hypoxia early - before clinical symptoms develop.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2015-04-08T18:08:35.493" LastActivityDate="2015-04-08T18:08:35.493" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13942" PostTypeId="2" ParentId="13895" CreationDate="2015-04-08T17:58:31.107" Score="-1" Body="&lt;p&gt;Yes. But with any modifications, the airplane will need to get re-certified by the authorities (FAA in the US) and approved, because it would have sustained modification to its structure.&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T17:58:31.107" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13943" PostTypeId="2" ParentId="13919" CreationDate="2015-04-08T18:26:14.610" Score="18" Body="&lt;p&gt;The simple answer is to rent or buy a supplemental O2 system for Mom.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't fake this one.  As Voretaq7 said in the first answer, &quot;A person experiencing symptoms of acute hypoxia&quot;  Focus on the word &quot;acute&quot;.  Just having your Mom feeling a little light-headed is probably not going to hold up as a valid reason to divert lower in any faa action. And if their google-fu is good and they find this website, you will not be able to claim that you were not aware of the potential for a problem.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for my warnings:  They are serious about the altitude restrictions over the Grand Canyon.  Diverting should be reserved for a truly unexpected emergency.  Just get the supplemental O2 system and you are covered.   &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-04-08T21:23:14.293" LastActivityDate="2015-04-08T21:23:14.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13944" PostTypeId="2" ParentId="13447" CreationDate="2015-04-08T19:24:10.673" Score="1" Body="&lt;p&gt;In an airplane, safety is more important than any other factor (after that comes optimum weight for fuel efficiency, and overall cost is third). If airplane would not be safe, not enough people would fly, and the airline industry would collapse. That's why there are FAA regulations, and that's why there are so many rules for the airlines. (the airport security check is another subject, related to national/political security with immigration, etc, so when we say 'safety' of the airplane, I mean engineering-wise)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Critical systems on board (i.e. systems that are &lt;em&gt;required&lt;/em&gt; to fly the airplane) will need redundancy. Like the burner in the jet engine has 2 igniter, even though one is enough. Also, if an engine fails, the other engine can fly the airplane, and the computer will compensate for the left/right force imbalance. Many systems in the airplane rely on the computer so it needs to have a 'plan b' (redundancy is one of the 'plan b')&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2015-04-08T19:24:10.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13946" PostTypeId="2" ParentId="13912" CreationDate="2015-04-08T20:39:49.073" Score="5" Body="&lt;p&gt;Not answered yet is this part of the question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How often do they rotate the ship if this is the case?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;First, just a nomenclature alert: ships don't rotate, they maneuver, steer, or change course.  And the answer to your question is: whenever necessary.  It is a big ocean and unless there is an island or something nearby, they always face the wind for air ops.  Note that with the angle decks, they want the wind coming directly down the angled deck so the ship is actually heading a little off to the right of the wind to accomplish this.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-04-08T20:39:49.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13948" PostTypeId="2" ParentId="13895" CreationDate="2015-04-08T23:06:16.637" Score="6" Body="&lt;p&gt;I used to fly a Twin Otter aircraft that was used in the UK to carry cargo (newspapers) at night and passengers in the day. The seats were carried in the rear of the aircraft and the pilot who flew it at night put the seats in before he went home. No certification was needed as there were no modifications.&lt;/p&gt;&#xA;" OwnerUserId="8064" LastActivityDate="2015-04-08T23:06:16.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13950" PostTypeId="2" ParentId="13908" CreationDate="2015-04-09T00:41:15.693" Score="7" Body="&lt;p&gt;Fixed wing aircraft will never land the wrong way on the boat.  However, I've done it many times in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_SH-3_Sea_King&quot; rel=&quot;noreferrer&quot;&gt;H-3&lt;/a&gt;.  It's a difficult landing even in a helo, the ship is closing on you and you have a tailwind.  The approach becomes excessively steep very quickly.&lt;/p&gt;&#xA;" OwnerUserId="8068" LastEditorUserId="1696" LastEditDate="2015-04-09T03:03:37.243" LastActivityDate="2015-04-09T03:03:37.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13951" PostTypeId="1" AcceptedAnswerId="13954" CreationDate="2015-04-09T04:35:18.173" Score="4" ViewCount="1548" Body="&lt;p&gt;I read that pilots often use printed checklists. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this a legal requirement, or are there also electronic versions available?&lt;/p&gt;&#xA;" OwnerUserId="8069" LastEditorUserId="6919" LastEditDate="2015-04-09T05:04:47.327" LastActivityDate="2015-04-09T13:15:27.180" Title="Do pilots use electronic checklists?" Tags="&lt;preflight&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13952" PostTypeId="2" ParentId="13951" CreationDate="2015-04-09T04:55:07.653" Score="2" Body="&lt;p&gt;Newer, more advanced, more expensive aircraft ever more come with computers that have checklists built in that can be displayed on a screen on the flight deck. Think the Boeing 777 or Airbus A380 for example.&lt;br/&gt;&#xA;This might be optional or standard depending on aircraft type.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Are there regulations preventing such things from being turned into software for mobile devices? I doubt it, long as the device itself is approved and the software can get approved for reliability and accuracy.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;But you'd be unlikely to be able to make something like that unless you're working for or contracted by an aircraft manufacturer as you'd not have access to the data needed for the software to display. That data isn't static and is copyrighted (so you can't just take an old paper checklist and turn it into some html pages for example).&lt;br/&gt;&#xA;You'd have to have some way to update the checklists as new versions are released, and that'd mean having channels with the manufacturer to gain access to their data (which may not be available at all electronically, you'd likely not be able to get it except for the same aircraft that already have such systems built in, making the entire idea superfluous).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-04-09T04:55:07.653" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13954" PostTypeId="2" ParentId="13951" CreationDate="2015-04-09T13:15:27.180" Score="5" Body="&lt;p&gt;Yes they do, and &lt;a href=&quot;http://lessonslearned.faa.gov/Northwest255/E_Checklists.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;according to the FAA&lt;/a&gt; they're better than paper ones. All sorts of aircraft can have electronic checklists, from large airliners to small Cessnas: modern avionics like the G1000 &lt;a href=&quot;http://aviationmentor.blogspot.com/2014/01/electronic-checklist-redux.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;support checklists&lt;/a&gt; and the older but very common GNS430 &lt;a href=&quot;http://static.garmincdn.com/pumac/GNS430_PilotsGuide.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;does too&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US at least there's no legal requirement to use checklists in any form - electronic or paper - with some caveats:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They're considered a fundamental best practice in aviation, so if you don't use them then someone could argue that you're acting &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow noreferrer&quot;&gt;carelessly or recklessly&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Incorrect - especially missing or incomplete - checklist use &lt;a href=&quot;http://flightdeck.ie.orst.edu/ElectronicChecklist/HTML/accidents.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;has been linked to many accidents&lt;/a&gt; (see &lt;a href=&quot;https://aviation.stackexchange.com/q/986/62&quot;&gt;this question&lt;/a&gt; too) so clearly it's in your own best interests to use them properly&lt;/li&gt;&#xA;&lt;li&gt;If you're flying for an airline then your &lt;a href=&quot;https://aviation.stackexchange.com/q/1641/62&quot;&gt;OpSpec&lt;/a&gt; probably requires use of checklists, in which case they're mandatory&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As for mobile devices, there are already many &lt;a href=&quot;https://www.foreflight.com/support/foreflight-checklist&quot; rel=&quot;nofollow noreferrer&quot;&gt;EFB applications&lt;/a&gt; and &lt;a href=&quot;https://play.google.com/store/search?q=checklist&amp;amp;c=apps&quot; rel=&quot;nofollow noreferrer&quot;&gt;standalone apps&lt;/a&gt; that support &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2014/April/04/Checklist-apps-Check&quot; rel=&quot;nofollow noreferrer&quot;&gt;checklists&lt;/a&gt;. In some cases the app provides a template for a specific aircraft type, in others you have to enter it all yourself. There may be some copyright considerations, but third-party checklists are &lt;a href=&quot;http://www.sportys.com/pilotshop/catalogsearch/result/?q=checklists&quot; rel=&quot;nofollow noreferrer&quot;&gt;very widely available&lt;/a&gt; so obviously it isn't a huge issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, it's worth noting that many pilots - especially those who own their own aircraft - &lt;a href=&quot;http://flighttraining.aopa.org/fsb/news/140602should-you-customize-your-checklists.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;customize checklists&lt;/a&gt; for their own needs. &lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-09T13:15:27.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13956" PostTypeId="2" ParentId="9005" CreationDate="2015-04-09T15:03:41.080" Score="14" Body="&lt;p&gt;There are a few factors that come into play. I will try and provide what they have and how to get around them. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Locked airport...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most airports I have been to have some form of a fence, gate etc so you would need to get past that first. Chances are there are also cameras but a ski mask and gloves will help you out with that. Smaller fields may have less protection and you may even be able to walk right up to the hangar. But you may draw more attention to your self as the people at the smaller fields may know each other better and know that its not your plane. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Locking the plane up...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some GA planes are hangared in presumably locked hangars. So the first thing you would need to do is get into the hangar. In this case we are talking about a door lock or a pad lock of sorts which can be generally opened with &lt;a href=&quot;http://www.lockpickshop.com/MPXS-14.html&quot;&gt;this&lt;/a&gt; if you practice a bit. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ok now you are in the hangar/have the hangar door open...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most General aviation planes do have door locks form what I have seen. These locks tend to be of the smaller key type (think pad lock key size) but Im sure they vary and newer planes carry larger keys. Most of the locks I have seen can be picked with something like &lt;a href=&quot;http://www.lockpickshop.com/MPXS-14.html&quot;&gt;this.&lt;/a&gt; There are types of locks that are better at preventing picks (like tubular) but they too can be picked. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ok now you are in the plane...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Maybe the plane has a prop lock (you can get that off with a bolt cutter, but don't nick the prop). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe the plane has a throttle lock, back to our lock picker to get that off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need to start the plane up. Here you have a few options one of which is to use the lock picker to turn the ignition key. Personally I would not do this for simple flight safety reasons. In this case you would bring along 3 switches with wires hanging off of them (this would work better on older planes) get under the panel and splice in some bypass switches. This would allow you to control each mag and the starter. You could also try a simple flat head screw driver and some good old force to break the tumbler and operate the starter. On newer planes with sleeker one piece dashes you may have an issue getting being it to hot wire it but I would think there is a way. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ok now the engine is started....&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The plane is running and you are taxing out, assuming no one in a nearby hangar asked you what you were doing and where Bob (our fictitious victim) was and why you were flying Bobs planes. No one is going to stop you on the taxi way or from the tower as far as I know. Now you are in the air, flying VFR to somewhere. Lets say Bob still has no idea his plane is missing since he does not intend to use it all week. You get to your home base airport with the plane and still no one is wise to what you have done. Maybe its even a private strip and no one else is there to say anything. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Now you have the plane in a &quot;safe&quot; place....&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The first thing you do is get the plane out of sight, put it in a barn maybe, get out your aircraft paint stripper and get rid of that N-Number would be your first task. Maybe strip more of the paint so as to make the plane harder to identify. Now you are thinking you will do one of two things with the plane, use it your self or sell it. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But you need an N-Number...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The first thing you will need to do is get a new N-Number for the plane this is where you will hit a problem as the airframe is already registered to Bob so you can't use that airframe number. I am under the impression that this where the road will end for you as its harder to fake an airplane number since they are far more closely tracked than say a car vin where you can use one out of a wrecked car (to an extent, its still illegal but technically can be done) There may be salvation laws for planes as well that you can exploit here if you can get a wrecked version of the same plane. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But Can I Sell It...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Maybe you can part it out and sell it, plane parts do command a high price. But with out the log books you may have an issue proving the time on a lot of the parts. Chances are Bob did not leave his aircraft logs in the plane but maybe he did (bad idea Bob). Now you can just part it out but you cant sell the whole plane. In trying to do that someone is going to be asking about the lack of N-Number and the log books. But hey, you tried. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What about a joy ride...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well sure, we have already established that you can get into the plane and fly it away, you could very well return it (with a bunch of broken locks) to where you found it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The only question is can you fly the plane... &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Remember every plane is different, while you may be able to saunter into the cockpit of some pretty heavy metal you may have no idea what you are doing or how to get it off the ground. I have no idea how to start a jet engine so I doubt I could just hop in one and fly away no matter how accessible the plane is. Lets say you have used X-Plane a bit to much and know how to start up and (theoretically) fly the plane, everyone here knows that theory and practice are not the same thing. Even if I got into the cockpit of a running jet I would still need to actually fly it. So on some level you are limited by experience unless you are a well trained pilot, well trained thief, and in general a criminal.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note I do not condone or endorse (or have ever been involved in) aircraft theft in any way. For the sake of argument I am presenting the facts to answer a hypothetical question. If for any thing, don't ruin Bob's week.... &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-09T15:03:41.080" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13957" PostTypeId="1" AcceptedAnswerId="13978" CreationDate="2015-04-09T15:29:23.727" Score="11" ViewCount="10243" Body="&lt;p&gt;According to the theory I know, lift is produced by accelerating air downwards at the trailing edge (&lt;a href=&quot;http://en.wikipedia.org/wiki/Downwash&quot; rel=&quot;noreferrer&quot;&gt;downwash&lt;/a&gt;). Hence, as downwash increases so does lift. Induced drag is due to &lt;a href=&quot;http://en.wikipedia.org/wiki/Vortex&quot; rel=&quot;noreferrer&quot;&gt;vortices&lt;/a&gt; at the wing tips and they also create downwash. So according to the above theory induced drag should also increase lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, the books say that induced drag increases downwash and reduces the effective &lt;a href=&quot;http://en.wikipedia.org/wiki/Angle_of_attack&quot; rel=&quot;noreferrer&quot;&gt;AOA&lt;/a&gt;, which subsequently &lt;em&gt;reduces&lt;/em&gt; the lift. Does the downwash from induced drag increase or decrease lift?&lt;/p&gt;&#xA;" OwnerUserId="6857" LastEditorUserId="62" LastEditDate="2015-04-09T18:50:51.350" LastActivityDate="2017-11-28T15:33:26.823" Title="Does the downwash created by induced drag increase or decrease lift?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;drag&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="13958" PostTypeId="1" CreationDate="2015-04-09T15:38:11.240" Score="9" ViewCount="1726" Body="&lt;p&gt;Here is something that happened to me: my flight was 3 hours late because the plane arrived late. We were told that a further 3-hour delay was expected because our flight had lost the &lt;a href=&quot;http://en.wikipedia.org/wiki/Landing_slot&quot;&gt;slots&lt;/a&gt; it had in the air traffic system, and we couldn't immediately get new slots due to very high congestion in the skies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, all the passengers were immediately boarded, all the flight procedures were initiated (safety film etc.), the plane taxied towards the runway and immediately departed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After landing I asked the pilot how the 3 extra hours we had to wait due to congestion suddenly &quot;disappeared&quot;. He told me that congestion is fluid and sometimes things change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can things change so much so quickly? Is the pilot's explanation plausible or is there another story behind what we were told by the airline?&lt;/p&gt;&#xA;" OwnerUserId="8076" LastEditorUserId="62" LastEditDate="2015-04-09T16:54:11.450" LastActivityDate="2015-04-09T19:49:20.393" Title="How can take-off slots suddenly become available even when airspace is congested?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13960" PostTypeId="1" AcceptedAnswerId="13961" CreationDate="2015-04-09T16:28:25.083" Score="7" ViewCount="8122" Body="&lt;p&gt;Are there any airports with ILS working CATIIIC? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do the charts for this procedure look like? Is there a missed approach procedure?&lt;/p&gt;&#xA;" OwnerUserId="8058" LastEditorUserId="1467" LastEditDate="2015-04-09T16:41:08.840" LastActivityDate="2015-04-09T16:51:28.060" Title="Which airports have ILS Cat IIIC?" Tags="&lt;landing&gt;&lt;airport&gt;&lt;regulations&gt;&lt;ils&gt;&lt;visibility&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13961" PostTypeId="2" ParentId="13960" CreationDate="2015-04-09T16:41:04.243" Score="6" Body="&lt;p&gt;This is not implemented anywhere in the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As of 2012 this category is not yet in operation anywhere in the world&#xA;  as it requires guidance to taxi in zero visibility as well. Category&#xA;  IIIc is not mentioned in EU-OPS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/105924/&quot;&gt;Airliners&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As far as I know NO airport in the world currently offers catIIIc as&#xA;  it has the most ridiculous minima both in the horizontal and vertical&#xA;  plane ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-04-09T16:41:04.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="13962" PostTypeId="2" ParentId="13960" CreationDate="2015-04-09T16:51:28.060" Score="4" Body="&lt;p&gt;There would still need to be a missed approach procedure, since plenty of things besides &quot;not seeing the runway/lights&quot; can cause the need for a go-around: equipment malfunction, traffic on the runway, winds shifting out of limits, etc.  So no matter how &quot;good&quot; the approach is, it still has to have a defined missed approach procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That procedure might well mirror the Cat I missed approach instructions.  Not certainly, but they often do.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-09T16:51:28.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13963" PostTypeId="2" ParentId="13933" CreationDate="2015-04-09T17:27:31.890" Score="1" Body="&lt;p&gt;With a foreign license you are only allowed to fly aircraft which are registered to the same country as your license in foreign countries. This is the way the international treaty system works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to fly the plane out yourself legally, you would have to get it registered in Brazil somehow first, or get some kind of special permission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One type of permission is called a &quot;special purpose pilot authorization&quot; (see &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.77&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.77&lt;/a&gt;). You may be able to get such a special authorization for a one-time flight, even if the aircraft is US registered. If I were you, I would call up the FAA and ask them about it.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-04-09T17:27:31.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13964" PostTypeId="1" AcceptedAnswerId="13974" CreationDate="2015-04-09T17:35:59.247" Score="3" ViewCount="2825" Body="&lt;p&gt;I am a long-time flight simulator player and also very interested in aviation. In &lt;a href=&quot;http://en.wikipedia.org/wiki/Microsoft_Flight_Simulator_X&quot; rel=&quot;nofollow&quot;&gt;FSX&lt;/a&gt;, all aircraft have a GPS/NAV knob which allows the pilot to switch between direct GPS autopilot and VOR navigation Autopilot. However, when I look at the main panel of a real Boeing cockpit, I don't see a GPS knob but I do see NAV V and NAV L buttons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know what NAV V and NAV L are (V for vertical autopilot, and L is the same as the NAV mode in FSX that keeps the plane on course), but do real aircraft (specially Boeing) have any function to keep the aircraft automatically on course and direct it toward the destination without using a VOR? Something that works very much like the GPS mode in FSX? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And in FSX I have to manually set the VOR frequency based on the navigation chart, in real life do the pilots have to do the same, or do they have some more advanced features?&lt;/p&gt;&#xA;" OwnerUserId="8077" LastEditorUserId="62" LastEditDate="2015-04-09T18:43:28.963" LastActivityDate="2015-04-09T20:11:11.310" Title="Do real aircraft have something close to the GPS/NAV modes in FSX?" Tags="&lt;boeing&gt;&lt;boeing-737&gt;&lt;gnss&gt;&lt;flight-simulator&gt;&lt;vor&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13965" PostTypeId="1" CreationDate="2015-04-09T19:03:45.603" Score="17" ViewCount="24593" Body="&lt;h1&gt;This is funny!&lt;/h1&gt;&#xA;&lt;p&gt;Please post &lt;strong&gt;jokes&lt;/strong&gt;, &lt;strong&gt;pictures&lt;/strong&gt;, &lt;strong&gt;cartoons&lt;/strong&gt;, &lt;strong&gt;videos&lt;/strong&gt; related to pilots, air/ground controllers, aircraft mechanics, flight/cabin/ground crew or anyone/anything related to aviation.&lt;/p&gt;&#xA;&lt;h1&gt;Rules&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any material should not be offensive, rude or insulting to any group.&lt;/li&gt;&#xA;&lt;li&gt;If that material requires proper attribution, please verify that by posting it here, no copyright rules are being violated.&lt;/li&gt;&#xA;&lt;li&gt;You can add your own personal story as a joke. However, this is not the &lt;a href=&quot;http://aviation.blogoverflow.com/&quot; rel=&quot;noreferrer&quot;&gt;Aviation Blog&lt;/a&gt;. We &lt;strike&gt;are quite active over there and&lt;/strike&gt; will be very happy if you want to contribute. Please come visit the &lt;a href=&quot;http://chat.stackexchange.com/rooms/info/13831/readback&quot;&gt;chat room Readback&lt;/a&gt;, and ping the owner of the room for permissions.&lt;/li&gt;&#xA;&lt;li&gt;This post is &lt;em&gt;not&lt;/em&gt; for rep generation, hence all posts should be &lt;a href=&quot;https://meta.stackexchange.com/q/11740/231188&quot;&gt;wiki&lt;/a&gt;. Mods are watching, and one of them has a cattle prod &lt;em&gt;(yes, the electric one)&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The material you are posting should be strictly related to aviation.&lt;/li&gt;&#xA;&lt;li&gt;Make sure that the post is readable, and properly formatted.&lt;/li&gt;&#xA;&lt;li&gt;Brevity is a virtue.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Please remember:&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Before flagging it as off-topic, or too broad, or low quality (really, doesn't that depend on you), please refer to &lt;a href=&quot;https://aviation.meta.stackexchange.com/q/1565/65&quot;&gt;this discussion&lt;/a&gt; behind the motive of this post. More information is present in the links in that question and the comment which follows.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-07-07T20:26:32.477" Title="What is your favorite aviation joke?" Tags="&lt;humor&gt;" AnswerCount="14" CommentCount="8" FavoriteCount="14" ClosedDate="2015-04-10T14:02:29.687" CommunityOwnedDate="2015-04-09T22:05:47.933" ContentLicense="CC BY-SA 3.0" />
  <row Id="13966" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T19:11:38.243" Score="19" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Etb3X.jpg&quot; alt=&quot;Picture of an aircraft&amp;#39;s wing, with 4 engines. A twin-engine aircraft is visible at a lower altitude.&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://rwrant.co.za/wp-content/uploads/2014/03/Geeky-Stuff-18.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Please click here for the source of this image.&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-04-09T19:11:38.243" CommentCount="0" CommunityOwnedDate="2015-04-09T19:11:38.243" ContentLicense="CC BY-SA 3.0" />
  <row Id="13967" PostTypeId="2" ParentId="13907" CreationDate="2015-04-09T19:17:11.803" Score="1" Body="&lt;p&gt;Here are some other methods (excluding CFD and computational ones) for building up a polar curve:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind tunnel testing, one of the earliest methods, still one of the most applied and explored one.&lt;/li&gt;&#xA;&lt;li&gt;Flight testing (&quot;dynamically scaled&quot; model or a 1:1 real prototype)&lt;/li&gt;&#xA;&lt;li&gt;Empirical methods (e.g. Hoerner's books on &quot;Lift&quot; and &quot;Drag&quot;)&lt;/li&gt;&#xA;&lt;li&gt;Reverse calculations; i.e. if the performance charts AND the engine deck (force model) is published or known, then the flight performance chapter of the aircraft operations manual could be used, at least to a certain confidence level, to guess about the polar curve for different configurations and conditions.&lt;/li&gt;&#xA;&lt;li&gt;If you know a few speeds of best endurance/best range glide, you could get an idea of the CL/CD at those speeds, and if you know the mass of the aircraft, the polar curve can be plotted.&lt;/li&gt;&#xA;&lt;li&gt;Asking the manufacturer certainly could help (if not a model of commercial competition)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-04-09T19:17:11.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13968" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T19:26:16.833" Score="6" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rDrVz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Source is Punditkitchen.com, but the page seems not to exist anymore)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-04-09T19:26:16.833" CommentCount="0" CommunityOwnedDate="2015-04-09T19:26:16.833" ContentLicense="CC BY-SA 3.0" />
  <row Id="13969" PostTypeId="2" ParentId="12892" CreationDate="2015-04-09T19:44:24.863" Score="0" Body="&lt;p&gt;Rotation increases the angle of attack, and as a result, the lift force also increases. However, there are aircraft that do take off with very little angle of attack change (maybe a couple of degrees, as in the case of UAVs). For those aircraft the lift force before rotation can be 60-70 % of the weight of the aircraft. Remember, for take off to happen, the lift force must be at least equal to the take off weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One more parameter is, of course, the airspeed. The lift increases with the square of the airspeed. And at the time of rotation, comparing just before and just after liftoff, the lift generated are quite close to each other, depending on the change of alpha (angle of attack). At a stationary airplane, with no headwind, there is no lift (&lt;em&gt;ignore engine flow&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sum up, during the ground roll, from standby to rotation, the lift increases from zero to a large fraction of the weight. The fraction depends on the type and design of the aircraft, but cannot be equal to the weight.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-04-09T19:44:24.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="13970" PostTypeId="2" ParentId="13958" CreationDate="2015-04-09T19:49:20.393" Score="11" Body="&lt;p&gt;It's a very credible explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slots to allocate scarce ATC and airport resources are created based on a known rate at which the airport/airspace can handle traffic, and they are apportioned out based on things like when the flightplans are filed, allowing for time enroute and expected arrival times.  (This is a little general -- trying to give a big picture without getting mired in too many specifics of EDCT's, Ground Delay Programs, and so forth -- some of those details can be found in answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/159/what-are-the-differences-between-ground-stop-ground-delay-and-gate-hold&quot;&gt;this question&lt;/a&gt;.)  When total demand is below capacity, it's common to be told to &quot;contact Clearance Delivery 5 minutes prior to Push for your wheels up time to XYZ,&quot; and then on calling Clearance, you're either given a wheels-up time in about 15-20 minutes (i.e. push on time, taxi out, and take off with no delays) or even &quot;released with no restrictions.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, when demand is greater than capacity (most common when a bottle-neck is caused by something like bad weather at the destination reducing the allowable arrival rate, although also caused when a runway or an approach is unusable for some length of time), then things start to slow down, and you may be given a wheels up time farther off in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Better to sit at the gate not burning gas than burning gas at idle out on a taxiway, or burning a LOT of gas holding in the air, but not most flyers' idea of a good time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When things are HIGHLY saturated, as it sounds like the OP's scenario, you can't get your slot time issued until you are actually ready to go, but you (or your dispatcher) may have a sense for what sort of delay is likely.  In these cases, you often can see where some aircraft have been given a significant delay, and anticipate something similar -- but you don't actually know what you'll get until you call.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sounds like the crew for the OP's flight anticipated that they MIGHT be pretty far back in line, and explained things accordingly, but when they actually called then either conditions had improved, OR a particular slot was available (perhaps another flight had cancelled or been delayed) and they got it.  That's not all that uncommon -- you call for your time, hoping for the best &amp;amp; prepared for the worst, and sometimes you get the &quot;wheels-up&quot; time 90 minutes out, and sometimes you get &quot;can you be wheels up in 12 minutes?&quot; and if the answer's &quot;yes&quot; then there's a quick high-five in the cockpit and &quot;tell 'em to shut the door, we're going!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the lead times involved, when a slot opens up like this, ATC typically does NOT call every flight &quot;in the queue&quot; to shift everybody forward by 5 minutes; that slot either gets used by somebody, or it's just unfilled.  But when we've told our passengers &quot;you can get off the airplane, be back by X so we can leave,&quot; making adjustments to that X time isn't practical, so for us that time is pretty well set.  Somebody else who IS boarded up &amp;amp; ready may get that fallout slot ahead of us, and when he does, good for him.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-04-09T19:49:20.393" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13971" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T19:50:21.047" Score="27" Body="&lt;h1&gt;Pilots Vs Maintenance Engineers&lt;/h1&gt;&#xA;&lt;p&gt;After every flight, pilots fill out a form, called a “gripe sheet” which tells mechanics about problems with the aircraft. The mechanics correct the problems; document their repairs on the form, and then pilots review the gripe sheets before the next flight.&lt;/p&gt;&#xA;&lt;p&gt;Never let it be said that ground crews lack a sense of humor. Here are some actual maintenance complaints submitted by pilots (marked with a P) and the solutions recorded (marked with an S) by maintenance engineers.&lt;/p&gt;&#xA;&lt;p&gt;P: Left inside main tire almost needs replacement.&lt;br /&gt;&#xA;S: Almost replaced left inside main tire.&lt;/p&gt;&#xA;&lt;p&gt;P: Test flight OK, except auto-land very rough.&lt;br /&gt;&#xA;S: Auto-land not installed on this aircraft.&lt;/p&gt;&#xA;&lt;p&gt;P: Something loose in cockpit.&lt;br /&gt;&#xA;S: Something tightened in cockpit.&lt;/p&gt;&#xA;&lt;p&gt;P: Dead bugs on windshield.&lt;br /&gt;&#xA;S: Live bugs on back-order.&lt;/p&gt;&#xA;&lt;p&gt;P: Autopilot in altitude-hold mode produces a 200 feet per minute descent.&lt;br /&gt;&#xA;S: Cannot reproduce problem on ground.&lt;/p&gt;&#xA;&lt;p&gt;P: Evidence of leak on right main landing gear.&lt;br /&gt;&#xA;S: Evidence removed.&lt;/p&gt;&#xA;&lt;p&gt;P: #2 Propeller seeping prop fluid&lt;br /&gt;&#xA;S: #2 Propeller seepage normal – #1 #3 and #4 propellers lack normal seepage&lt;/p&gt;&#xA;&lt;p&gt;P: DME volume unbelievably loud.&lt;br /&gt;&#xA;S: DME volume set to more believable level.&lt;/p&gt;&#xA;&lt;p&gt;P: Friction locks cause throttle levers to stick.&lt;br /&gt;&#xA;S: That’s what they’re for&lt;/p&gt;&#xA;&lt;p&gt;P: IFF inoperative.&lt;br /&gt;&#xA;S: IFF always inoperative in OFF mode.&lt;/p&gt;&#xA;&lt;p&gt;P: Suspected crack in windshield.&lt;br /&gt;&#xA;S: Suspect you’re right.&lt;/p&gt;&#xA;&lt;p&gt;P: Number 3 engine missing.&lt;br /&gt;&#xA;S: Engine found on right wing after brief search.&lt;/p&gt;&#xA;&lt;p&gt;P: Aircraft handles funny.&lt;br /&gt;&#xA;S: Aircraft warned to straighten up, fly right, and be serious.&lt;/p&gt;&#xA;&lt;p&gt;P: Target radar hums.&lt;br /&gt;&#xA;S: Reprogrammed target radar with lyrics&lt;/p&gt;&#xA;&lt;p&gt;P: Mouse in cockpit.&lt;br /&gt;&#xA;S: Cat installed.&lt;/p&gt;&#xA;&lt;p&gt;And the best one for last.&lt;/p&gt;&#xA;&lt;p&gt;P: Noise coming from under instrument panel. Sounds like a midget pounding on something with a hammer.&lt;br /&gt;&#xA;S: Took hammer away from midget.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://aviationhumor.net/pilots-vs-maintenance-engineers/&quot; rel=&quot;noreferrer&quot;&gt;(Source)&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-09T19:50:21.047" CommentCount="0" CommunityOwnedDate="2015-04-09T19:50:21.047" ContentLicense="CC BY-SA 3.0" />
  <row Id="13972" PostTypeId="2" ParentId="55" CreationDate="2015-04-09T19:54:21.000" Score="1" Body="&lt;p&gt;An FBO in the USVI &lt;a href=&quot;http://www.allianceaviation.net/customs-preclearance.html&quot; rel=&quot;nofollow&quot;&gt;offers the following explanation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When an aircraft that is inspected by CBP in the U.S. Virgin Islands arrives in the United States, it is considered to be pre-cleared.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, you must be able to provide evidence of the inspection, and must arrive at an airport with CBP facilities unless that requirement is waived by the CBP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title19-vol1/xml/CFR-2012-title19-vol1-sec122-24.xml&quot; rel=&quot;nofollow&quot;&gt;19 CFR § 122.24&lt;/a&gt; discusses &quot;Landing requirements for certain aircraft arriving from areas south of U.S.&quot;, which states that aircraft must provide advance notice of arrival and stop at the nearest &quot;designated airport&quot;, but also includes the following exception:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;This requirement shall not apply&lt;/strong&gt; to those aircraft which have not landed in foreign territory or are arriving directly from Puerto Rico, &lt;strong&gt;if the aircraft was inspected by CBP officers in the U.S. Virgin Islands&lt;/strong&gt;, or otherwise precleared by CBP officers at designated preclearance locations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-04-09T19:54:21.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13973" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T20:09:07.660" Score="10" Body="&lt;p&gt;This picture always give me a good chuckle &#xA;&lt;img src=&quot;https://i.stack.imgur.com/YcxbP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As does this one &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NL9Jn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-09T20:09:07.660" CommentCount="0" CommunityOwnedDate="2015-04-09T20:31:07.383" ContentLicense="CC BY-SA 3.0" />
  <row Id="13974" PostTypeId="2" ParentId="13964" CreationDate="2015-04-09T20:11:11.310" Score="5" Body="&lt;p&gt;In the Boeing world, LNAV is Lateral Navigation, and VNAV is Vertical Navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When LNAV is engaged, the autopilot will follow the Flight Management Computer (FMC) guidance laterally, i.e. left &amp;amp; right.  When VNAV is engaged, the autopilot will follow the FMC guidance vertically, i.e. climbs &amp;amp; descents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LNAV is conceptually pretty simple: you have a magenta line on the map, your desired course, and the autopilot will follow it.  The points defining your course are database points in the FMC that may but certainly do not have to correspond with VOR's or other conventional NavAids.  You can use LNAV to fly VOR-to-VOR, or it can fly point-to-point-to-point equally easily.  (You don't have to tune any frequencies in either case.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VNAV is a little more complicated, because you may only be cleared for some of what the FMC wants to do vertically.  Simple example: you're cruising at FL370, planning to start down at a given point so as to cross AAA at FL240, and then continue the descent to cross BBB and 10,000' and 250 knots.  ATC clears you to &quot;descend at pilot discretion, maintain FL 290.&quot;  That means you can start down at whatever point you want, but until you get cleared lower later on, you can't descend all the way to FL240 or 10,000.  Yet.  Or maybe the controller needs to put you at FL350 right now to avoid a traffic conflict 100 miles ahead, and your clearance is &quot;descend now and maintain FL350, pilot discretion FL290.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a lengthy section of Ground School how the pilot sets up the FMC and the mode control panel to accomplish all of this, but hopefully that illustrates some of the complexity of VNAV.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a good system; under typical conditions you can go into LNAV and VNAV shortly after takeoff and stay in them both until shortly before landing, and the FMC gives you smooth (mostly) and efficient guidance.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-09T20:11:11.310" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13975" PostTypeId="2" ParentId="1738" CreationDate="2015-04-09T20:22:42.200" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2999/1696&quot;&gt;As discussed here&lt;/a&gt;, glide ratio is related to the L/D (lift-to-drag) ratio of the plane. When talking about commercial aircraft, &quot;glide ratio&quot; is typically used to mean the ratio with engines inoperative. If the jet engines aren't running, they add a lot of drag, which will decrease the L/D ratio from the typical max value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.lissys.demon.co.uk/samp1/&quot; rel=&quot;nofollow noreferrer&quot;&gt;This analysis&lt;/a&gt; estimates the max L/D of the 787 at &lt;strong&gt;20.8&lt;/strong&gt;, while &lt;a href=&quot;http://seekingalpha.com/article/2494925-boeing-the-airbus-a330neo-a-real-competitor-for-the-boeing-787-part-3&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; estimates &lt;strong&gt;21&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other sources estimate L/D of the &lt;a href=&quot;http://www.researchgate.net/profile/Roberto_Sabatini2/publication/268814067_Advanced_Lightweight_Aircraft_Design_Configurations_for_Green_Operations/links/5478454a0cf293e2da288c58.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A330&lt;/a&gt; and &lt;a href=&quot;https://books.google.com/books?id=HWPXH0id5jQC&amp;amp;lpg=PA261&amp;amp;ots=bZuWB0Qb6_&amp;amp;dq=a340%20%22L%2FD%22&amp;amp;pg=PA262#v=onepage&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;A340&lt;/a&gt; at &lt;strong&gt;20&lt;/strong&gt;. &lt;a href=&quot;http://commons.erau.edu/cgi/viewcontent.cgi?article=1007&amp;amp;context=jaaer&quot; rel=&quot;nofollow noreferrer&quot;&gt;The 747&lt;/a&gt; is estimated at about &lt;strong&gt;18&lt;/strong&gt;. So based on these estimates, the 787 is slightly better than other large airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the efficiency gains of the 787 are from the lower weight of composite materials (which allow bigger wings) and more efficient engines.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2019-03-13T01:54:33.540" LastActivityDate="2019-03-13T01:54:33.540" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="13976" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T20:41:47.050" Score="15" Body="&lt;p&gt;Saint Peter was standing at the Pearly Gates, and a pilot walks up and says &quot;My name is Joe, I'm a pilot, I think you've got a place for me.&quot; Saint Peter starts flipping through his book. Flip, flip, flip... &quot;Ah yes Joe, here you are. Take this golden staff, harp, and silk robe, and pass through to the right where you'll meet the choir you've been assigned.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A minute later, another man walks up. &quot;Hello Saint Peter, My name is Bob. I'm a retired pastor. I think you've got a place for me.&quot; Saint Peter starts flipping through his book. Flip, flip, flip.... &quot;Ah yes, Bob, here you are. Take this &lt;em&gt;wooden&lt;/em&gt; staff, this &lt;em&gt;ukulele&lt;/em&gt;, and this &lt;em&gt;cotton&lt;/em&gt; robe, and pass through to the right where you'll meet the choir you've been assigned.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bob says (a little miffed) &quot;Well, alright I guess... but why did that pilot guy get all that fancy stuff?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Saint Peter says &quot;Well y'see Bob, we work on the cause-and-effect principle here. While you spent years preaching, most of your congregation was asleep. When Joe there was flying, everybody who flew with him was &lt;em&gt;praying.&lt;/em&gt;&quot;&lt;/p&gt;&#xA;" OwnerUserId="6840" LastActivityDate="2015-04-09T20:41:47.050" CommentCount="0" CommunityOwnedDate="2015-04-09T20:48:47.770" ContentLicense="CC BY-SA 3.0" />
  <row Id="13977" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T21:01:55.497" Score="2" Body="&lt;p&gt;Guy I used to know but have since lost contact with had as his email signature &quot;I'd rather smoke and fly than drink and drive&quot;.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Always thought that a rather good one.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-04-09T21:01:55.497" CommentCount="0" CommunityOwnedDate="2015-04-09T22:05:47.933" ContentLicense="CC BY-SA 3.0" />
  <row Id="13978" PostTypeId="2" ParentId="13957" CreationDate="2015-04-09T21:16:47.290" Score="18" Body="&lt;p&gt;It is not &quot;this causes that&quot; - all is happening together. Let me explain:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me to understand aerodynamics, it helped to disregard all that talk of vortices and induction, but focus on the pressure field around a wing. When the theory of flight was developed, electricity was new and exciting, and it just happened that electric induction could be transferred to lift. Now every author still copies the explanations from a century ago, but they are totally unintuitive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every air molecule is in a dynamic equilibrium between inertial, pressure and viscous effects. Inertial means that the mass of the particle wants to travel on as before and needs force to be convinced otherwise. Pressure means that air particles oscillate all the time and bounce into other air particles. The more bouncing, the more force they experience. Viscosity means that air molecules, because of this oscillation, tend to assume the speed and direction of their neighbors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the airflow: When a wing approaches at subsonic speed, the low pressure area over its upper surface will suck in air ahead of it. See it this way: Above and downstream of a packet of air we have less bouncing of molecules (= less pressure), and now the undiminished bouncing of the air below and upstream of that packet will push its air molecules upwards and towards that wing. The packet of air will rise and accelerate towards the wing and be sucked into that low pressure area. Once there, it will &quot;see&quot; that the wing below it curves away from its path of travel, and if that path would remain unchanged, a vacuum between the wing and our packet of air would form. Reluctantly, the packet will change course and follow the wing's contour, but not without spreading out (= pressure loss). Spreading happens in flow direction - the packet is distorted and stretched lengthwise, but contracts in the direction orthogonally to the flow. This fast-flowing, low-pressure air will in turn suck in new air ahead and below of it, will go on to decelerate and regain its old pressure over the rear half of the wing, and will flow off with its new flow direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A packet of air which ends up below the wing will experience less uplift and acceleration, and in the convex part of highly cambered airfoils it will experience a compression. It also has to change its flow path, because the cambered and/or inclined wing will push the air below it downwards, creating more pressure and more bouncing from above for our packet below the wing. When both packets arrive at the trailing edge, they will have picked up some downward speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V7Ujo.png&quot; alt=&quot;Airfoil in wind tunnel with smoke trails indicating flow&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Behind the wing, both packets will continue along their downward path for a while due to inertia and push other air below them down and sideways. Above them, this air, having been pushed sideways before, will now fill the space above our two packets. Macroscopically, this looks like two big vortices. But the air in these vortices cannot act on the wing anymore, so it will not affect drag or lift. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;here for more on that effect&lt;/a&gt;, including pretty pictures.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What is lift?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Following the picture of a pressure field outlined above, lift is the difference of pressure between upper and lower surface of the wing. The molecules will bounce against the wing skin more at the lower side than at the upper side, and the difference is lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or you look at the macroscopic picture: A certain mass of air has been accelerated downwards by the wing, and this required a force to act on that air. This force is what keeps the aircraft up in the air: Lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, you will arrive at the same result. By the way: Most of the directional change happens in the forward part of the airfoil, not at the trailing edge!&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Induced drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The misconception about those &quot;wingtip vortices&quot; and induced drag is hard to eradicate. Most authors copy what has been written before without clearly understanding the issue. Therefore I repeat it here again: &lt;strong&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3428/do-box-wings-suffer-from-induced-drag-the-same-way-as-normal-wings/3467#3467&quot;&gt;Induced drag&lt;/a&gt; is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;backward-pointing part&lt;/a&gt; of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529#7529&quot;&gt;pressure force vector&lt;/a&gt;&lt;/strong&gt;. The vortices are only a consequence of downwash, which in turn is a consequence of lift creation. At the same speed, more induced drag is indeed linked to more lift, but the causality is different: Lift and induced drag are both part of the pressures acting on the wing. If you add up all the pressure forces acting on a wing, their resulting vector will point slightly backwards. The streamwise component is drag, and the component orthogonal to the direction of movement is lift. This is just a defininion, made for simplicity.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-05-10T08:43:12.387" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="13979" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T21:58:40.070" Score="6" Body="&lt;p&gt;One day in the not too distant future, so the hoary old story goes, airliners will have only two crew members on the flight deck — a pilot and a dog. At the press conference on the occasion of the introduction of the first of those airliners, the journalists ask: &quot;What is the job of the dog?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answer: &quot;To bite the pilot if he touches the controls!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Journalists: &quot;Makes sense. But why keep the pilot in the cockpit?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answer: &quot;Someone has to to feed the dog!&quot;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-04-09T21:58:40.070" CommentCount="0" CommunityOwnedDate="2015-04-09T21:58:40.070" ContentLicense="CC BY-SA 3.0" />
  <row Id="13980" PostTypeId="1" CreationDate="2015-04-09T22:25:05.937" Score="6" ViewCount="4174" Body="&lt;p&gt;Do Airbus pilots normally disengage the Auto Throttle on a manual landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do pilots (Airbus or Boeing) normally prefer a manual landing to a A/P landing?&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="65" LastEditDate="2015-04-10T13:46:26.297" LastActivityDate="2015-04-10T13:46:26.297" Title="What configuration of autothrottle is required when pilots are landing an Airbus?" Tags="&lt;landing&gt;&lt;airbus&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="13981" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T22:27:54.180" Score="4" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yO1cb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image has been taken from &lt;a href=&quot;http://www.chickenwingscomics.com/692/turn-to-a-heading-of-120/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ChickenWings Comics&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-04-09T22:27:54.180" CommentCount="0" CommunityOwnedDate="2015-04-09T22:27:54.180" ContentLicense="CC BY-SA 3.0" />
  <row Id="13982" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T22:36:40.610" Score="3" Body="&lt;p&gt;Controller: United 6, make a 360. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot: Approach, this here is a 747 that costs \$12000 per hour to operate.  a 360 takes 10 minutes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controller: Great, give me a \$2,000 turn.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pilot: Sydney Approach, United 5, 10,000. We happy to be visiting your little island, and we have the airport in sight 12 o'clock. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approach: United 5, roger. Turn right, follow the coast, expect the visual for 35.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="72" LastEditDate="2015-04-10T00:28:27.987" LastActivityDate="2015-04-10T00:28:27.987" CommentCount="5" CommunityOwnedDate="2015-04-09T22:36:40.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="13983" PostTypeId="2" ParentId="13965" CreationDate="2015-04-09T23:32:40.177" Score="5" Body="&lt;p&gt;The advantage of a twin engine plane over single engine?  The second engine gets you to the crash site faster.&lt;/p&gt;&#xA;" OwnerUserId="8082" LastActivityDate="2015-04-09T23:32:40.177" CommentCount="1" CommunityOwnedDate="2015-04-09T23:32:40.177" ContentLicense="CC BY-SA 3.0" />
  <row Id="13984" PostTypeId="2" ParentId="13980" CreationDate="2015-04-10T00:26:20.503" Score="-1" Body="&lt;p&gt;Most (but absolutely not all) pilots let the aircraft land itself most of the time.  I asked a number of different pilots this question (30+ year captain at USAirways, a 3 year FO at Spirit, a 20+ year captain at Delta) and their estimate was that 75% or more of landings were done via auto-pilot.  One of these pilots was almost exclusively Boeing, one was almost exclusively Airbus, and the other estimated that his experience was roughly 60% Boeing.&lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-04-10T00:26:20.503" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="13985" PostTypeId="2" ParentId="13965" CreationDate="2015-04-10T00:28:16.310" Score="21" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fMuHx.png&quot; alt=&quot;Don&amp;#39;t click on the wing.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation related xkcd has to be here somewhere at least  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://xkcd.com/726/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://xkcd.com/726/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="309" LastEditorUserId="8300" LastEditDate="2017-07-07T20:26:32.477" LastActivityDate="2017-07-07T20:26:32.477" CommentCount="2" CommunityOwnedDate="2015-04-10T00:28:16.310" ContentLicense="CC BY-SA 3.0" />
  <row Id="13986" PostTypeId="2" ParentId="13965" CreationDate="2015-04-10T00:31:07.710" Score="3" Body="&lt;p&gt;A crew member just gets hired on as a new flight attendant.  On their very first flight the crew has a three day layover.  The captain shows the flight attendant around the city including some of the best restaurants and hotels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the crew is finally ready for their return trip they just can't find the new flight attendant anywhere.  The airplane takes off in half an hour and the new flight attendant is nowhere to be found.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain calls the hotel that the flight attendant is staying at, he gets put through to get room.  The flight attendant answers the phone, and the captain is freaking out he says &quot;Why are you in your room!?  We are supposed to be in the air in 30 minuets!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight attendant is in tears and replies &quot;I am stuck in my room, there's no way out!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain asks how this is possible, knowing it's such a nice hotel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight attendant responds. &quot;There's two doors, one is the bathroom, and the other says 'DO NOT DISTURB.'&quot;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="69" LastEditDate="2015-06-08T20:50:45.153" LastActivityDate="2015-06-08T20:50:45.153" CommentCount="0" CommunityOwnedDate="2015-04-10T00:31:07.710" ContentLicense="CC BY-SA 3.0" />
  <row Id="13988" PostTypeId="2" ParentId="13965" CreationDate="2015-04-10T02:36:13.970" Score="16" Body="&lt;p&gt;Tower: &quot;TWA 2341, for noise abatement turn right 45 Degrees.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TWA 2341: &quot;Center, we are at 35,000 feet. How much noise can we make up here?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tower: &quot;Sir, have you ever heard the noise a 747 makes when it hits a 727?&quot;&lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2015-04-10T02:36:13.970" CommentCount="0" CommunityOwnedDate="2015-04-10T02:36:13.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="13989" PostTypeId="2" ParentId="13965" CreationDate="2015-04-10T02:38:43.697" Score="11" Body="&lt;p&gt;A beautiful young blonde woman boards a plane to New York with a ticket in economy.  Noticing an empty seat in first class, she moves up and sits down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight attendant checks her ticket and tells the woman she needs to move back to economy.  The blonde replies, &quot;I have never had this problem before. I'm going to sit here until we get to New York.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The captain, having been informed of the situation, goes back and tells the blonde that her assigned seat is in economy, and again, she replies the same.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not wanting to cause a commotion, the captain returns to the cockpit to discuss the situation with the first officer.  The FO says his girlfriend is blonde, and that he'll take care of it.  He goes back and whispers something in the blonde's ear.  Immediately she gets up, thanks the FO profusely, and returns to economy.  The captain and flight attendant are stunned and ask the FO how he was able to so quickly diffuse the situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FO replies, &quot;I just told her that the first class section isn't going to New York.&quot;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-04-10T02:38:43.697" CommentCount="5" CommunityOwnedDate="2015-04-10T02:38:43.697" ContentLicense="CC BY-SA 3.0" />
  <row Id="13990" PostTypeId="2" ParentId="13980" CreationDate="2015-04-10T07:09:20.250" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Do Airbus pilots normally disengage the Auto Throttle on a manual landing ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Depends on what you mean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the initial part of the approach, no, they do not deactivate the autothrust (not autothrottle, in this case):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FcjYG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the autothrust is not designed for landing and just before touchdown there is an automatic callout in the cockpit: &lt;code&gt;Retard. Retard.&lt;/code&gt; (it can be heard in &lt;a href=&quot;https://www.youtube.com/watch?v=9svSePWwisQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; 4 times). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The callout is needed because of the A/THR inner working: while in &lt;code&gt;SPEED mode&lt;/code&gt; it can apply any throttle between 0 and the current throttle lever position; i.e., if for example the throttle is at the 80% setting, the autothrust can apply any throttle between 0% and 80% (based on the required airspeed). At the &lt;code&gt;Retard&lt;/code&gt; callout the pilots will move the levers to the IDLE position, effectively deactivating the autothrust:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/koMK1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-04-10T11:28:25.297" LastActivityDate="2015-04-10T11:28:25.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13991" PostTypeId="1" AcceptedAnswerId="13992" CreationDate="2015-04-10T09:40:01.013" Score="9" ViewCount="816" Body="&lt;p&gt;Airspaces have a lateral and vertical boundary, which results in airspaces adjoining other and thus having a shared vertical boundary. Which airspace class do these shared vertical boundaries belong to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&#xA;Dortmund's (&lt;a href=&quot;https://skyvector.com/airport/EDLW/Dortmund-Wickede-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;EDLW&lt;/a&gt;) control zone is a class D from &lt;code&gt;GND/SFC&lt;/code&gt; to &lt;code&gt;2500ft MSL&lt;/code&gt;, on top of this control zone is a TMA airspace class D from &lt;code&gt;2500ft MSL&lt;/code&gt; to &lt;code&gt;4500ft MSL&lt;/code&gt; thereafter class E from &lt;code&gt;4500ft MSL&lt;/code&gt; to &lt;code&gt;FL100&lt;/code&gt;and above that we have class C airspace from &lt;code&gt;FL100&lt;/code&gt; to &lt;code&gt;FL660&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lFRNx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.skyvector.com - Map Data: skyvector, ARINC, OpenStreetMap)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft wants to occupy &lt;code&gt;2500ft MSL&lt;/code&gt;, &lt;code&gt;4500ft MSL&lt;/code&gt; or &lt;code&gt;FL100&lt;/code&gt;, which airspace class are they in?&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-04-10T09:55:07.033" LastActivityDate="2015-04-10T09:55:07.033" Title="When airspaces adjoin vertically, which airspace class does the shared flight level or altitude belong to?" Tags="&lt;airspace&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="13992" PostTypeId="2" ParentId="13991" CreationDate="2015-04-10T09:40:01.013" Score="8" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.bazl.admin.ch/experten/regulation/03080/03081/index.html?lang=de&amp;amp;download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1acy4Zn4Z2qZpnO2Yuq2Z6gpJCDeoB9f2ym162epYbg2c_JjKbNoKSn6A--&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Annex 11 - ATS (Air Traffic Services)&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;, the less restrictive airspace is in effect on shared boundaries:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note.— Where the ATS airspaces adjoin vertically, i.e. one above the other, flights at a common level would comply with&#xA;  requirements of, and be given services applicable to, the less restrictive class of airspace. In applying these criteria, Class B&#xA;  airspace is therefore considered less restrictive than Class A airspace; Class C airspace less restrictive than Class B&#xA;  airspace, etc. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unless national regulations in the country's AIP are in contradiction or the national AIP does not list any information on this, the ICAO regulation will apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the above example, the altitudes or flight level would be considered:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;2500ft MSL&lt;/code&gt;: Class D airspace&lt;br&gt;&#xA;&lt;code&gt;4500ft MSL&lt;/code&gt;: Class E airspace, since class E is less restrictive than class D&lt;br&gt;&#xA;&lt;code&gt;FL100&lt;/code&gt;: Class E airspace, since Class E is less restrictive than class C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related questions:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/13204/572&quot;&gt;What is the difference between “flight level” and “altitude”?&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/2917/572&quot;&gt;What is the difference between the airspace's classes (for non-pilots)?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-04-10T09:40:01.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13995" PostTypeId="1" CreationDate="2015-04-10T15:18:13.137" Score="6" ViewCount="749" Body="&lt;p&gt;It has often been said on this site that induced drag on wings is the inevitable result of producing lift over a finite length. Converting this to the realm of propulsion, I assume that propellers have &quot;induced drag&quot; or something similar, as they produce thrust over a finite length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a ducted fan, the airstreams above and below the airfoil can't just &quot;slip around the side,&quot; because they're blocked by the duct. My intuition thus suggests that ducted fans would not have induced drag (or its equivalent), assuming that the space between the blades and the duct is negligible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this accurate?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="1467" LastEditDate="2015-04-10T15:43:42.580" LastActivityDate="2015-04-11T14:21:27.490" Title="Do ducted fans eliminate induced drag?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13998" PostTypeId="1" AcceptedAnswerId="13999" CreationDate="2015-04-10T17:11:47.070" Score="22" ViewCount="22068" Body="&lt;p&gt;There are two main types of aerial refueling, the boom and the drogue. The US uses both, while most other countries use just the drogue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are they different and why does the US use both?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2018-10-31T08:07:19.923" Title="Why does the US use two types of aerial refueling?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;refueling&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="13999" PostTypeId="2" ParentId="13998" CreationDate="2015-04-10T17:11:47.070" Score="23" Body="&lt;p&gt;The &lt;strong&gt;flying boom method&lt;/strong&gt; uses a rigid boom which is &quot;flown&quot; by an operator in coordination with the pilot in order to make a connection with a receptacle on the second aircraft. The boom is retracted when not in use. Though &lt;a href=&quot;http://en.wikipedia.org/wiki/1966_Palomares_B-52_crash&quot; rel=&quot;noreferrer&quot;&gt;it can do damage&lt;/a&gt; if it comes in contact with an aircraft, &lt;a href=&quot;http://newsok.com/old-video-shows-near-midair-collision-involving-oklahoma-refueling-tanker/article/3722677&quot; rel=&quot;noreferrer&quot;&gt;the operator can quickly move the boom if needed&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fdLXh.jpg&quot; alt=&quot;Refueling with boom&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;probe and drogue method&lt;/strong&gt; uses a trailing hose with a basket on the end. Pilots will guide a probe on their aircraft into the basket to connect with the hose. The hoses are retracted when not in use. Though the crew has less control of the drogue, which &lt;a href=&quot;https://books.google.com/books?id=sNYDBwAAQBAJ&amp;amp;lpg=PA121&amp;amp;pg=PA121#v=onepage&quot; rel=&quot;noreferrer&quot;&gt;can still cause damage&lt;/a&gt;, there is less danger to the aircraft than from a boom, and it could allow the aircraft to stay further away from the tanker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yWY9e.jpg&quot; alt=&quot;Refueling with drogue&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The boom method was developed early on in the Cold War, when &lt;a href=&quot;http://en.wikipedia.org/wiki/Operation_Chrome_Dome&quot; rel=&quot;noreferrer&quot;&gt;Strategic Air Command had many large bombers that needed to be refueled&lt;/a&gt;. They needed a method that would transfer fuel as fast as possible in order to reduce the time it took to transfer the large amounts of fuel needed. Because the boom is rigid, it is capable of a higher transfer rate. The importance of bombers meant that SAC got their way, and the KC-135 fleet was equipped with booms. Today, almost all US Air Force planes capable of aerial refueling use the boom system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Navy on the other hand, along with most aircraft in other countries, uses the drogue system. Though this method is not capable of the high transfer rates of a boom, it is much more flexible. A refueling aircraft may only be fitted with one boom, and this requires extra design work and integration with the fuselage. The drogue system, on the other hand, is more simple, and does not need a dedicated operator. This means that it can be more easily fitted to the refueling aircraft, even &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet&quot; rel=&quot;noreferrer&quot;&gt;other fighter planes&lt;/a&gt;, and larger aircraft can have multiple drogues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point is that smaller aircraft such as fighters are not capable of receiving fuel at the full rate the boom provides, so they have less benefit from the system. Although a boom can have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Aerial_refueling#Boom_drogue_adapter_units&quot; rel=&quot;noreferrer&quot;&gt;drogue adapter attached&lt;/a&gt;, this still commits the tanker to one aircraft at a time and one type of system per flight. Also, aircraft such as helicopters &lt;a href=&quot;https://aviation.stackexchange.com/q/12006/1696&quot;&gt;cannot use a boom system&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the Air Force was looking at a replacement for its tanker fleet in the early 2000s, a &lt;a href=&quot;https://www.fas.org/sgp/crs/weapons/RL32910.pdf&quot; rel=&quot;noreferrer&quot;&gt;study was done&lt;/a&gt; to determine what standard the new tanker should support.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report suggests some options for the best combination of methods. In the end, the Air Force selected the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_KC-46_Pegasus&quot; rel=&quot;noreferrer&quot;&gt;KC-46&lt;/a&gt; for the contract, which will include both the boom and the drogue options for refueling. This will provide better support to aircraft from other branches or countries, while maintaining support of the existing aircraft that use a boom.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-10T19:17:40.680" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14000" PostTypeId="1" CreationDate="2015-04-10T17:52:28.010" Score="-1" ViewCount="146" Body="&lt;p&gt;I came across an &lt;a href=&quot;http://www.johansens.us/sane/politics/airplane-cost.htm&quot; rel=&quot;nofollow&quot;&gt;interesting speculation&lt;/a&gt; that basically wondered if it would be more cost effective to use cheaper jets as fighters in greater numbers. I thought it may be plausible, but I wonder if there is someone who knows for sure.&lt;/p&gt;&#xA;" OwnerUserId="2910" LastEditorUserId="43" LastEditDate="2015-04-10T18:50:15.343" LastActivityDate="2015-04-10T18:50:15.343" Title="cost effective air power" Tags="&lt;military&gt;&lt;cost&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-04-10T18:59:03.193" ContentLicense="CC BY-SA 3.0" />
  <row Id="14001" PostTypeId="2" ParentId="13995" CreationDate="2015-04-10T17:59:58.960" Score="2" Body="&lt;p&gt;&lt;em&gt;EDIT: I'll add this ahead of the answer because it will necessarily come up: This answer is based on the model described by Prandtl, which is only that: A model, a simplified description for what happens that works to explain some phenomena. There is some disagreement about this model, so a separate explanation using a differen theory might help. The problem is that an explanation with pressure differences doesn't help much here, at least I wouldn't know how to answer the question without working with Helmholtz/Prandtl.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fundamentally, what we are talking about are vortex rings that are created because air is moved in some direction somewhere and not moved everywhere else. That's independent of how you move it, and fundamentally, a duct or winglet or something similar can't change that. You can look at the vortex itself as the thing that actually creates lift or thrust, so you want and need that vortex. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's &lt;a href=&quot;https://en.wikipedia.org/wiki/Helmholtz%27s_theorems&quot; rel=&quot;nofollow&quot;&gt;Helmholtz's theorems&lt;/a&gt;. Quick quote from that article:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Helmholtz’s first theorem:&lt;br&gt;&#xA;&lt;em&gt;The strength of a vortex filament is constant along its length.&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Helmholtz’s second theorem:&lt;br&gt;&#xA;&lt;em&gt;A vortex filament cannot end in a fluid; it must extend to the&#xA;boundaries of the fluid or form a closed path.&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the case of a normal wing, the vortex ring (&quot;closed path&quot;) consists of one side along the length of the wing, two sides trailing behind the wingtips and the fourth side is somewhat lost, or far enought away that it can mostly be ignored. The three sides that are not along the wing itself are the problem, they are what the term &quot;induced drag&quot; refers to. Because there is no surface at the end of the wing for the vortex to end at, it has to continue into infinity. And there is some friction involved in creating long fast-spinning vortices, so you get drag. (Any help in explaining this part more eloquently is appreciated)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the amount of lift/thrust that you want is given, the vortex strength isn't something that can be changed either. What can be changed, however, is the distribution/speed/radius. If the lift distribution is elliptical (see: Spitfire), the lift gradient is minimal across the wing so there is no strong and fast vortex at the end, it is gradually created along the whole wingspan and the induced drag is minimal. Winglets do something similar by forcing the vortex to go all the way around the winglet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a propeller, the inner side of the vortex ends at the spinner or shaft, so the ring is broken and you are only left with a linear vortex, but it is still trailing infinitely into the air at the tips of the blades. You can look at a wing in the same way if you interrupt the ring at the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a ducted fan, you have two fluid boundaries, both on the inside and on the outside, which appears to solve the problem. You can have a vortex around the blade only and no vortices trailing into infinity creating drag. The problem is that the fluid doesn't really end at the duct because the duct has a finite length. So what you get is a large vortex around the whole duct. Air is moving in at the front and out at the back, and somewhere, that air moves back to the front far away from the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a ducted fan, the vortex ring is created in the place where the moving air meets the static air at the beginning and end of the duct. Instead of a very small vortex around the tip of the wing (and along the wing, to not mess up Helmholtz's theorems), you get a larger one around the whole duct. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, I wouldn't say that the duct can eliminate induced drag. The effect is fundamentally comparable to a wingtip device: It increases the inner radius of the vortex and thereby reduces the induced drag significantly. It's far more effective at that than a wingtip device, but it has to be because ducted fans are usually relatively small so the drag would otherwise be enormous.&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="5665" LastEditDate="2015-04-10T18:21:24.473" LastActivityDate="2015-04-10T18:21:24.473" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14002" PostTypeId="2" ParentId="14000" CreationDate="2015-04-10T18:33:15.810" Score="2" Body="&lt;p&gt;The short answer is no and frankly the article says it all in the first paragraph... &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Now, I don't claim to have any expertise on aircraft design nor to have done any serious research on this subject,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not to mention that a new citation X costs 22.5 million (according to wikipedia) and the Mustang comes in at a mere 3.28 Million not the 2.5 million he seems to think. But still a a bit cheaper than some fighters.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But lets discuss it for a minute. First off military jets are far more complex aircraft and are capable of maneuvers that civilian aircraft simply are not. The cost of the jets is related in part to the complexity of actually building one and the fact that they often use simply more expensive materials like Titanium in simply more places than a civilian aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The author goes on to make some egregious claims about strapping weapons to a Citation. While this may be possible it would most likely cost more than anticipated not to mention large airframe modifications. If you simply are asking &quot;can you put some big guns on a citation&quot; the answer is in a since yes. Could you successfully dog fight with a citation, I doubt it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets look at his comparison with the Bede BD-5J, your limiting factor here is simply gross weight. In a plane that size you may be able to carry a 6-shooter (and if  you have been dieting all week) 6 bullets for it. Not making it a very effective fighter. This will come into play with the Citation as well but I dont know the loads they can haul so Im sure how much you will limit it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The argument here of masses with lesser technology holds little merit since in a dog fight situation the fighter is going to be simply faster and more maneuverable and even if you had 10000 Citations with guns the fighter can simply out run/maneuver them.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-10T18:33:15.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14003" PostTypeId="2" ParentId="14000" CreationDate="2015-04-10T18:45:47.577" Score="4" Body="&lt;p&gt;These days, fighters don't fight so much against each other as they fight against surface anti-air defences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And those Citations won't stand a chance against even simple AA gun battery. They don't have manoeuvrability to zigzag to make them harder targets, don't have manoeuvrability to fly at tree-top heights to minimize time in covered space and have huge radar cross-section, so the targeting radar will lock them from miles away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avoiding &lt;em&gt;these&lt;/em&gt; threats is what makes the fighters expensive.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-04-10T18:45:47.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14004" PostTypeId="2" ParentId="1102" CreationDate="2015-04-11T02:09:47.770" Score="0" Body="&lt;p&gt;Regarding EASA regulation 216/2008 and 1178/2011 (EU).  Since &lt;strong&gt;April 8, 2015&lt;/strong&gt;, the EU laws also require pilots who live in Europe, and fly a foreign registered aircraft (for example an N-registered aircraft) that they also have to have the EASA license.&#xA;There will be a postponement of this regulation by one year, i.e. until April 8, 2016, that the EU intends to publish in the coming weeks.&#xA;Until 2016, there will be a bilateral agreement between the EU and the USA, providing a simple mutual recognition of licenses, stand-alone licenses.&#xA;&lt;strong&gt;This will make it much easier to get a FAA stand-alone license.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="8090" LastEditorUserId="1467" LastEditDate="2015-04-11T06:28:39.050" LastActivityDate="2015-04-11T06:28:39.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14005" PostTypeId="2" ParentId="12947" CreationDate="2015-04-11T06:15:28.367" Score="2" Body="&lt;p&gt;They did design one plane with a siren to warn people on the ground.  The aircraft was called the &quot;Stuka&quot;&#xA;The pilot would diligently turn on the warning siren right before he nosed down and dove at 300 miles per hour to accurately release his bombs onto the people he was warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The warning siren terrorized the general public, so they stopped using it out of consideration for the bomber pilots, who didn't like getting shot down by the military employed to protect the public.&lt;/p&gt;&#xA;" OwnerUserId="8092" LastActivityDate="2015-04-11T06:15:28.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14006" PostTypeId="1" AcceptedAnswerId="14008" CreationDate="2015-04-11T08:04:29.490" Score="35" ViewCount="9818" Body="&lt;p&gt;On the first look this question might sound ridiculous and maybe it is. &#xA;But as propeller blades act by the same physical laws as wings, and winglets reduce the induced drag by quite a bit, then why are they not put on propeller blades? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could imagine that it might be a material problem. But are there any more reasons? And why exactly might it be a material problem? &lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2020-09-12T17:41:19.780" Title="Why do propeller blades not have winglets?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;winglets&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14007" PostTypeId="1" AcceptedAnswerId="14011" CreationDate="2015-04-11T11:44:55.987" Score="6" ViewCount="11542" Body="&lt;p&gt;What is the largest airport in terms of:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Size of developed area?&lt;/li&gt;&#xA;&lt;li&gt;Size of all terminal area?&lt;/li&gt;&#xA;&lt;li&gt;Total number of gates?&lt;/li&gt;&#xA;&lt;li&gt;Total number of gates + remote stands?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="167" LastEditDate="2015-04-11T21:03:37.360" LastActivityDate="2015-04-11T21:03:37.360" Title="What are the largest airports in terms of size, gates, and stands?" Tags="&lt;airport&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14008" PostTypeId="2" ParentId="14006" CreationDate="2015-04-11T11:59:42.047" Score="25" Body="&lt;p&gt;Winglets on wings help because they increase the volume of air on which the wing can act. &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;Extending the wing span would be much more efficient&lt;/a&gt;, but when span is restricted or the maximum wing bending moment is limited, winglets bring a small improvement in efficiency at high lift coefficients.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;On propellers&lt;/a&gt;, however, the winglets would run through air which is already affected by the tips of the propeller. No additional air will be involved, so no efficiency increase will be possible. Please note that propulsive efficiency is increased by accelerating more air by a smaller amount. The formula for the propulsive efficiency &lt;span class=&quot;math-container&quot;&gt;$\eta_p$&lt;/span&gt; of an air breathing engine is&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\eta_p = \frac{v_{\infty}}{v_{\infty} + \frac{\Delta v}{2}}$$&lt;/span&gt;&#xA;where &lt;span class=&quot;math-container&quot;&gt;$v_{\infty}$&lt;/span&gt; is the speed of the inflowing air and &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt; the speed increase of the air affected by the propeller disc. A smaller &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt; acting on a higher mass flow makes the engine more efficient. This effect is most pronounced when &lt;span class=&quot;math-container&quot;&gt;$v_{\infty}$&lt;/span&gt; is low.&lt;/p&gt;&#xA;&lt;p&gt;The prop tip winglets would operate in a region of high dynamic pressure and generate more friction drag without contributing to the prop's efficiency.&lt;/p&gt;&#xA;&lt;p&gt;Things become different when the propeller blades have a very low aspect ratio and there is a hard restriction on propeller diameter: This is true for ships, where draught puts a hard limit on propeller size. Here a sort of winglet does indeed help: The &lt;a href=&quot;https://www.mek.dtu.dk/english/Research/Feature_Articles/KAPPEL_Propeller&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kappel propeller&lt;/a&gt; has its tip bent forward and increases efficiency by 3 - 6 percent. Given that marine propellers even for large ships have efficiencies between 50% and 60%, this is a noteworthy increase in efficiency.&lt;/p&gt;&#xA;&lt;p&gt;By the way: Whoever tells you that winglets reduce induced drag &lt;strong&gt;quite&lt;/strong&gt; a bit has something to sell to you, but I digress.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-09-12T17:41:19.780" LastActivityDate="2020-09-12T17:41:19.780" CommentCount="21" ContentLicense="CC BY-SA 4.0" />
  <row Id="14009" PostTypeId="2" ParentId="13998" CreationDate="2015-04-11T12:23:17.253" Score="8" Body="&lt;p&gt;The US Air Force and the US Navy have a very different history, so they approach things quite differently and feel their respective way of doing things is superior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Air Force started as the Aeronautical Divison of the US Signal Corps and later became the US Army Air Forces (&lt;a href=&quot;http://en.wikipedia.org/wiki/United_States_Army_Air_Forces&quot; rel=&quot;nofollow noreferrer&quot;&gt;USAAF&lt;/a&gt;), and it inherited the traditions from the Army: Discipline and strict adherence to procedures, basically what was started when &lt;a href=&quot;http://en.wikipedia.org/wiki/Friedrich_Wilhelm_von_Steuben&quot; rel=&quot;nofollow noreferrer&quot;&gt;Baron von Steuben&lt;/a&gt; trained the first American soldiers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Navy used to give their commanders much more freedom: When away on a ship, the captain had to decide for himself what the best tactics would be. This can still be found in the Navy's flying forces today: Pilots are much more encouraged to think for themselves instead of following detailed procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, both will instinctively reject what the other prefers: When the Air Force selected the F-16, the Navy had to prefer the F-18. And so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aerial refuelling, it makes indeed more sense to use the boom technique when large amounts of fuel need to be transferred to big bombers. If you need to top up fuel for a number of smaller aircraft, however, the drogue-and-chute system is the better choice. The mutual competition between the Forces has only helped to cement this diversity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantages of the boom over the drogue technique are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;much higher transfer rate. This is the reason the boom method was developed to transfer lots of fuel to SAC (Strategic Air Command) bombers.  Other nations' bombers and large aircraft prefer the probe and drogue method. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Maneuvering is done by the boom operator. While the drogue method requires the recipient to manoeuver his aircraft's probe into the center of the drogue, the boom method requires the recipient only to fly in formation with the tanker while the boom operator does the rest.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are fewer boom operators than pilots, so the boom operator is likely to be more experienced in the refuelling process.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The disadvantages are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The tanker needs to be a big aircraft which can afford to include a boom operator compartment. There is no possibility for &lt;a href=&quot;https://airrefuelingarchive.wordpress.com/2012/02/05/fa-18e-buddy-refueling/&quot; rel=&quot;nofollow noreferrer&quot;&gt;buddy-buddy refuelling&lt;/a&gt; (except between two tankers).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also most aircraft, including many of the USAF, can not accept fuel at the rate that a boom can provide, so much of the extra capability goes unused.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Retrofitting existing aircraft for boom refueling is much more complex than mounting a fuel tank with a hose and drogue at its end to an aircraft.  Unless the aircraft in question is a large aircraft, the retrofit to boom is virtually impossible.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-04-02T07:05:56.273" LastActivityDate="2018-04-02T07:05:56.273" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14010" PostTypeId="2" ParentId="13995" CreationDate="2015-04-11T12:47:36.707" Score="2" Body="&lt;p&gt;You are absolutely right, a propeller suffers from induced drag just as a wing does, and there are methods to minimize this induced drag. Simply put, you should distribute thrust elliptically over the prop blade's span and accelerate all air flowing through the prop disc by an equal amount. This was first found by &lt;a href=&quot;http://en.wikipedia.org/wiki/Albert_Betz&quot; rel=&quot;nofollow noreferrer&quot;&gt;A. Betz&lt;/a&gt; in 1919 and later refined by &lt;a href=&quot;http://de.scribd.com/doc/82049292/Minimum-Induced-Loss-Propeller-E-Larrabee&quot; rel=&quot;nofollow noreferrer&quot;&gt;Larabee&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, adding a duct will not change the basic reason &lt;a href=&quot;https://aviation.stackexchange.com/questions/13957/does-the-downwash-created-by-induced-drag-increase-or-decrease-lift/13978#13978&quot;&gt;why induced drag occurs&lt;/a&gt;. We had this discussion already &lt;a href=&quot;https://aviation.stackexchange.com/questions/735/induced-drag-on-the-prop-and-prop-wing-lets/8796#8796&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/9940/what-are-the-advantages-and-disadvantages-of-ducted-fans-in-designs-such-as-the/9949#9949&quot;&gt;here&lt;/a&gt;. A duct helps to equalize and decelerate the flow and is used in fan engines, because they prefer to operate in air flowing &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;at a speed around Mach 0.5&lt;/a&gt;. But it will not help to reduce induced drag.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-11T14:21:27.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14011" PostTypeId="2" ParentId="14007" CreationDate="2015-04-11T13:22:24.693" Score="10" Body="&lt;ol&gt;&#xA;&lt;li&gt;According to &lt;a href=&quot;http://www.insidermonkey.com/blog/the-10-biggest-airports-in-the-world-334297/&quot;&gt;InsiderMonkey&lt;/a&gt; DFW (&lt;a href=&quot;http://en.wikipedia.org/wiki/Dallas/Fort_Worth_International_Airport&quot;&gt;Dallas/Fort Worth International Airport&lt;/a&gt;) is the largest at 4360 hectares.&lt;/li&gt;&#xA;&lt;li&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_largest_buildings_in_the_world&quot;&gt;Wikipedia&lt;/a&gt; DXB (&lt;a href=&quot;http://en.wikipedia.org/wiki/Dubai_International_Airport&quot;&gt;Dubai International Airport&lt;/a&gt;) has the largest terminal in terms of floorspace at 1,713,000 m2 (18,440,000 sq ft) with a volume of approximately 10.0 million m³ (360 million cu ft) &lt;/li&gt;&#xA;&lt;li&gt;According to &lt;a href=&quot;http://forum.skyscraperpage.com/showthread.php?t=204975&quot;&gt;this forum&lt;/a&gt; ATL (&lt;a href=&quot;http://en.wikipedia.org/wiki/Hartsfield%E2%80%93Jackson_Atlanta_International_Airport&quot;&gt;Hartsfield-Jackson Atlanta International Airport&lt;/a&gt;) has 206 gates&lt;/li&gt;&#xA;&lt;li&gt;Can't find this one&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-04-11T13:22:24.693" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14012" PostTypeId="2" ParentId="14007" CreationDate="2015-04-11T14:15:12.430" Score="5" Body="&lt;p&gt;I nominate &lt;a href=&quot;https://www.google.nl/maps/@32.153016,-110.8283374,1761m/data=!3m1!1e3&quot;&gt;Davis Monthan Air Force Base&lt;/a&gt; as the winner in category 4. Not for the number of gates, it is the number of remote stands that does it. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-04-11T14:15:12.430" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14014" PostTypeId="1" AcceptedAnswerId="14015" CreationDate="2015-04-11T22:08:06.637" Score="20" ViewCount="11037" Body="&lt;p&gt;Are there any commonly used passenger aircraft larger than regional jets (100+ seats) that aren't Boeing or Airbus? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what are they and where are they used?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-05-08T08:51:18.857" Title="Are there any airliners not made by Airbus or Boeing?" Tags="&lt;airliner&gt;&lt;boeing&gt;&lt;airbus&gt;&lt;airlines&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14015" PostTypeId="2" ParentId="14014" CreationDate="2015-04-11T22:21:05.773" Score="36" Body="&lt;p&gt;Yes. Ignoring companies that used to exist but are now bankrupt/merged into Airbus or Boeing, you have companies from countries that aren't historically too friendly with the US and Western Europe. For instance, Tupolev makes the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-204&quot;&gt;Tu-204&lt;/a&gt;, which is currently in production and seats over 175 passengers. The Ilyushin-designed &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-96&quot;&gt;Il-96&lt;/a&gt; is a widebody in current use some places (Russia, Cuba). Before the Cold War ended, Russia had more indigenous airliners; Aeroflot now largely uses Boeings and Airbuses, but there are still Russian aircraft that see use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, you have newer manufacturers starting to enter the market: Bombardier with their &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CSeries&quot;&gt;CSeries&lt;/a&gt;, Comac (in China) with their &lt;a href=&quot;https://en.wikipedia.org/wiki/Comac_C919&quot;&gt;C919&lt;/a&gt; (in development), and Irkut with their &lt;a href=&quot;https://en.wikipedia.org/wiki/Irkut_MC-21&quot;&gt;MC-21&lt;/a&gt; (in development). Embraer makes &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_E-Jet_family&quot;&gt;planes of more than 100 seats&lt;/a&gt; (although they're shorter-range, and you might consider them regional jets). &lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="5665" LastEditDate="2015-04-12T10:10:32.913" LastActivityDate="2015-04-12T10:10:32.913" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14016" PostTypeId="1" CreationDate="2015-04-11T22:44:20.577" Score="9" ViewCount="1779" Body="&lt;p&gt;I know there are busy airports without control towers, and the converse is also true. There is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1218/whats-the-process-for-an-uncontrolled-airfield-to-become-controlled-towered&quot;&gt;process for an airport to acquire a control tower&lt;/a&gt;. Sometimes, airports want to have &lt;a href=&quot;https://aviation.stackexchange.com/questions/3292/can-an-airport-without-an-faa-controlled-tower-have-their-own-tower-and-controll&quot;&gt;their own control tower&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some activity level where an airport would &lt;strong&gt;require&lt;/strong&gt; a control tower for safe operation? Or does air traffic control exist simply to reduce risk?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-11T23:34:07.523" Title="When is a control tower required?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;non-towered-airport&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14017" PostTypeId="2" ParentId="14016" CreationDate="2015-04-11T23:34:07.523" Score="7" Body="&lt;p&gt;As far as I'm aware there's no specific regulation that &lt;strong&gt;&lt;em&gt;requires&lt;/em&gt;&lt;/strong&gt; a control tower to be established. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=pt14.3.170&amp;amp;rgn=div5#sp14.3.170.b&quot;&gt;FAR 170&lt;/a&gt; and the regs referenced therein set out when an airport becomes &lt;em&gt;eligible&lt;/em&gt; for a tower, but nothing requires an eligible field to have a control tower (in fact the FAA won't establish a tower unless someone &lt;em&gt;gives&lt;/em&gt; them the land).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said it would probably be a Bad Idea&lt;sup&gt;tm&lt;/sup&gt; for certain airports to operate without a control tower (Atlanta, Kennedy, O'Hare, LAX...) - in fact those airports are busy enough that they have &lt;em&gt;additional&lt;/em&gt; traffic management procedures in place beyond what a control tower can provide.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Control towers exist to improve safety (improve risk) as you alluded to. There are procedures and rules established to allow pilots to self-sequence at untowered fields &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot;&gt;(you'll find those in section 4-1-9 of the AIM)&lt;/a&gt;, and they work very well when everyone follows them.&lt;br&gt;&#xA;The catch is everybody doesn't follow those procedures - or more accurately they're followed with varying degrees of precision (my personal favorite example of sloppy procedure is when you hear someone say &quot;any traffic in the area please advise&quot; at an uncontrolled field). These procedures also don't cover other movements on the airport surface very well: Some pilots will announce their taxi plan at an uncontrolled field, but there are plenty of pilots who taxi from point A to point B with their head up and their mouth shut so as not to tie up the frequency for aircraft in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the number of operations increases at an airport the various degrees of precision and adherence to the uncontrolled-field procedures in the AIM  becomes more of an issue, and a control tower may be established by the FAA or the local airport authority to safely and efficiently coordinate aircraft movements.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-04-11T23:34:07.523" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14018" PostTypeId="1" AcceptedAnswerId="14048" CreationDate="2015-04-11T23:45:09.503" Score="7" ViewCount="2116" Body="&lt;p&gt;At larger airports, common taxi instructions are sometimes &quot;named&quot; for brevity as they are repeated often. For (an entirely contrived) example, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxi to terminal via alpha, tango, foxtrot, mike four, sierra&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;could be shortened to something like&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxi via red-flower&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Where can these common taxi route definitions be found?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-04-11T23:46:21.040" LastActivityDate="2015-04-13T12:22:16.273" Title="Where can I find airport taxi instruction &quot;code names&quot;?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14019" PostTypeId="2" ParentId="14018" CreationDate="2015-04-12T01:47:35.673" Score="7" Body="&lt;p&gt;If it's not a taxi-way odd name(Inner/Outer/Dixie, etc) that's on the chart, it's usually a procedure that's in a letter of agreement with the specific airline/companies. I know at Atlanta, there's a Letter of Agreement with some of the airlines(Delta I know for sure, not positive about others and don't have access from home to the repository), where they'll taxi via the Victor loop, which denotes taxi-ways, and when to change to the appropriate ground control frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To find these out, you'd have to be privy to the specific LOA at each airport. Or if you've flown in and out of the airport enough you will often be able to figure them out by watching those privy to the LOA and what they do.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-04-12T01:47:35.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14020" PostTypeId="2" ParentId="14014" CreationDate="2015-04-12T02:27:51.577" Score="6" Body="&lt;p&gt;The MD-80 series is still in fairly widespread use, and it wasn't made by Boeing or Airbus either.  The MD-11 is getting harder to find in passenger service, although it's still used for cargo.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-12T02:27:51.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14021" PostTypeId="2" ParentId="14014" CreationDate="2015-04-12T03:09:36.470" Score="4" Body="&lt;p&gt;Bombardier make regional jets but their new &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CSeries&quot; rel=&quot;nofollow&quot;&gt;C series&lt;/a&gt; is a 737/A320 class 80-120 seat aircraft&lt;/p&gt;&#xA;" OwnerUserId="1576" LastActivityDate="2015-04-12T03:09:36.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14022" PostTypeId="2" ParentId="14014" CreationDate="2015-04-12T06:46:04.410" Score="28" Body="&lt;p&gt;Being used but out of production:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ilyushin Il-62 (up to 195 seats): last one built in 2010. Totally built 287, 13 remain in service&lt;/li&gt;&#xA;&lt;li&gt;Tupolev Tu-154 (up to 176 seats): last one built in 2013. Totally built 923, 61 remain in service&lt;/li&gt;&#xA;&lt;li&gt;Ilyushin Il-86 (up to 350 seats): last one built in 1995, since 2011 only in military use. Totally built 106, 4 remain in service&lt;/li&gt;&#xA;&lt;li&gt;Ilyushin Il-18 (up to 120 seats): last one built in 1985, but still in use by several airlines. Totally built 678 (other sources say 850+), 92 remain in service&lt;/li&gt;&#xA;&lt;li&gt;Yakovlev Yak-42 (100/120 seats): last one built in 2003, still in use. Totally built 187, 55 remain in service&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In production:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ilyushin Il-96 (300/436 seats), the 436-seat variant was never built, but freight variant can be converted to use 436 seats upon customer's request. Totally built 28 (incl freght variant), 15 remain in service&lt;/li&gt;&#xA;&lt;li&gt;Tupolev Tu-204 (up to 210 seats). Totally built 76, 46 remain in active service.&lt;/li&gt;&#xA;&lt;li&gt;Sukhoi SSJ-100 (98-108 seats). Totally built 77, 60 in active service&lt;/li&gt;&#xA;&lt;li&gt;Antonov An-158 (up to 99 seats). Totally built 6 (excluding the An-148 variant which has less seats), all 6 in active service.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4382" LastEditorUserId="4382" LastEditDate="2015-05-08T08:51:18.857" LastActivityDate="2015-05-08T08:51:18.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14023" PostTypeId="2" ParentId="3050" CreationDate="2015-04-12T06:53:21.877" Score="7" Body="&lt;p&gt;An emergency requiring a Service Difficulty Report (SDR), generated by owner self-reporting or investigation results, is reported by tail number. If you know the number, or other equipment identifying attribute, you can &lt;a href=&quot;http://www.aviationdb.com/Aviation/AircraftQuery.shtm&quot;&gt;search here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reports filed less than a week to 6 months after incident, FAA packages are published within a week. You can find these on this &lt;a href=&quot;http://av-info.faa.gov/dd_sublevel.asp?Folder=%5CSDRS&quot;&gt;FAA data source&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8097" LastEditorUserId="1467" LastEditDate="2015-04-12T07:05:35.520" LastActivityDate="2015-04-12T07:05:35.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14024" PostTypeId="2" ParentId="9860" CreationDate="2015-04-12T08:19:15.397" Score="0" Body="&lt;p&gt;Currently a major problem is that the amount of helium on Earth is limited. This lead to the sharp rise of helium prices and it is expected to rise further. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to use other gases, hydrogen is known to be dangerous and explosion-suspectible. It is also difficult to contain because it leaks envelope of any material due to the small size of its molecules.&lt;/p&gt;&#xA;" OwnerUserId="4382" LastActivityDate="2015-04-12T08:19:15.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14025" PostTypeId="2" ParentId="14014" CreationDate="2015-04-12T08:54:11.210" Score="2" Body="&lt;p&gt;Yes , of course.&lt;br&gt;&#xA;Tupolev, Antonov, Douglas(I thinks at least they made earlier) and Ilyushin have made many.&lt;br&gt;&#xA;While Boeing and Airbus are the most common, Russia, China , India etc. do use (or may be used) other airlines.&lt;/p&gt;&#xA;" OwnerUserId="8100" LastActivityDate="2015-04-12T08:54:11.210" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14026" PostTypeId="2" ParentId="14006" CreationDate="2015-04-12T09:12:27.600" Score="7" Body="&lt;p&gt;Hartzell make propellers that appear to have winglets (tips bent aft) called Q-tips. The name seems to refer to them being quieter. I have read that they do the same job as a slightly larger diameter prop. They seem to have no life issues. Since noise costs energy, and a smaller prop does the same job.... it is possible that they are more efficient. The bent tip is small - on the order of a couple of inches.&lt;/p&gt;&#xA;" OwnerUserId="7487" LastActivityDate="2015-04-12T09:12:27.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14027" PostTypeId="1" CreationDate="2015-04-12T09:14:12.437" Score="6" ViewCount="2331" Body="&lt;p&gt;I read about several aircraft crashes throughout aviation history and the investigations on wikipedia and also checked out some episodes of the documentary &quot;Air Crash Investigation&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While of course I can only make conclusions of what I read, hear and see it appears, that problems related to communication are one typical reason to contribute to such disasters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Something that attracted my attention is that the sidesticks used in the aircrafts of Airbus seem to be involved in not less than three crashes including &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow&quot;&gt;Air France Flight 447&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though there is the general distinction pilot flying (PF) and pilot not flying (PNF) failures, malfunctions and the triggered warnings tend to create a situation of stress and strain in the cockpit as comprehensible. Confusion comes up not seldom in such situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My point finally is, that&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Sidesticks are smaller than yokes. To apply a control input one only needs to turn one's wrist while a yoke requires you to use both of your arms to make the big aircraft turn. &lt;strong&gt;I wonder if the inhibition threshold therefore is somehow lower to make extreme, exaggerated inputs in case of a sidestick?&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Secondly, and this is the major question, as it appears, &lt;strong&gt;the sidesticks make it much harder, to be aware of the currently applied control input (especially) for the other pilot&lt;/strong&gt;. While the yokes of both pilots are physically connected and both pilots have direct feedback of the currents state at any given time, the sidesticks&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;give no feedback to the other sidestick&lt;/li&gt;&#xA;&lt;li&gt;are smaller, which makes it harder to see the current state their in already by the size alone&lt;/li&gt;&#xA;&lt;li&gt;are more distant than yokes making it again harder to see for the other pilot, as this &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/a/a4/Airbus_A380_cockpit.jpg&quot; rel=&quot;nofollow&quot;&gt;A380 cockpit shot&lt;/a&gt; shows&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Question:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How is the general assessment of those sidesticks concerning safety?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there any feedback to the pilots which stick is giving what input? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Has there been any development in improving this situation?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What are the accidents/incidents sidesticks more or less contributed to confusion/lack of information?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8101" LastEditorUserId="19" LastEditDate="2015-04-12T12:11:50.310" LastActivityDate="2015-04-13T16:05:32.087" Title="Sidestick safety concern" Tags="&lt;safety&gt;&lt;flight-controls&gt;&lt;sidestick&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ClosedDate="2015-04-13T12:33:24.100" ContentLicense="CC BY-SA 3.0" />
  <row Id="14029" PostTypeId="2" ParentId="2685" CreationDate="2015-04-12T11:20:22.433" Score="4" Body="&lt;p&gt;The autopilot and autothrottle were both disengaged and, thanks to the quick thinking of the Pilot Flying to activate the Auxiliary Power Unit (APU), the aircraft stayed in &lt;strong&gt;Normal Law&lt;/strong&gt;. This assisted when ditching due to the transition at 50ft to Flare Mode that causes a pitch down attitude allowing the pilot to pull back with a constant pressure on his side stick to cause the plane to flare for landing.&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="753" LastEditDate="2017-02-03T13:51:04.447" LastActivityDate="2017-02-03T13:51:04.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14030" PostTypeId="2" ParentId="14014" CreationDate="2015-04-12T12:10:57.427" Score="11" Body="&lt;p&gt;Boeing = Historic Boeing, not McDonnell Douglas, or plain Douglas &lt;br&gt;&#xA;Airbus = Historic Airbus. &lt;br&gt; &#xA;Commonly used= ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A reputable source would be &#xA;&lt;a href=&quot;http://www.airliners.net/aircraft-data/&quot;&gt;http://www.airliners.net/aircraft-data/&lt;/a&gt;&#xA;From there and comments here, I have edited the following list of manufacturers, for a concise answer, and below that, a list of the aircraft which I believe have more than 100 seats, or can be configured with 100 or more seats, and are in revenue service today, 2015:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aircraft  Manufacturers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Antonov &lt;/li&gt;&#xA;&lt;li&gt;Bombardier&lt;/li&gt;&#xA;&lt;li&gt;British Aerospace/AVRO&lt;/li&gt;&#xA;&lt;li&gt;Douglas, McDonnell-Douglas&lt;/li&gt;&#xA;&lt;li&gt;Embraer&lt;/li&gt;&#xA;&lt;li&gt;Fokker&lt;/li&gt;&#xA;&lt;li&gt;Ilyushin&lt;/li&gt;&#xA;&lt;li&gt;Sukhoi&lt;/li&gt;&#xA;&lt;li&gt;Tupolev&lt;/li&gt;&#xA;&lt;li&gt;Yakovlev&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&lt;br&gt;&#xA;&lt;strong&gt;Aircraft  Type&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Antonov An-124 Ruslan   Heavylift freighter &lt;br&gt;&#xA;Antonov An-140 New! Turboprop regional airliner &lt;br&gt;&#xA;Antonov An-225 Mriya    Extra-Large cargo aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bombardier CRJ-1000 (&amp;amp; C-100, C-300, when deliveries start)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BAE Systems Avro RJX100     Regional airliner &lt;br&gt;&#xA;British Aerospace Avro RJ85/100     Regional airliner &lt;br&gt;&#xA;British Aerospace BAe-146-200 &amp;amp;-300     Regional jet airliner &lt;br&gt;&#xA; &lt;br&gt;&#xA;Douglas DC-7    Piston engine airliner and freighter &lt;br&gt;&#xA;Douglas DC-8-60/70  Long range medium capacity airliner and freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Embraer ERJ-195      108 seat regional airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fokker 100  100 seat regional jet &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ilyushin Il-18  Medium range turboprop airliner &lt;br&gt;&#xA;Ilyushin Il-62  Medium to long range medium capacity airliner &lt;br&gt;&#xA;Ilyushin Il-76  Medium to long range freighter &lt;br&gt;&#xA;Ilyushin Il-86  Medium range widebody airliner &lt;br&gt;&#xA;Ilyushin Il-96-300  Long range widebody airliner &lt;br&gt;&#xA;Ilyushin Il-96M &amp;amp; Il-96T    Long range widebody airliner and freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;McDonnell Douglas DC-10 &amp;amp; Boeing MD-10  Medium to long range widebody airliner  &lt;br&gt;&#xA;McDonnell Douglas DC-9-40/50    Short to medium range airliners &lt;br&gt;&#xA;McDonnell Douglas MD-11     Long range widebody airliner &lt;br&gt;&#xA;McDonnell Douglas MD-81/82/83/88    Short to medium range airliner &lt;br&gt;&#xA;McDonnell Douglas MD-87     Short to medium range airliner &lt;br&gt;&#xA;McDonnell Douglas MD-90     Short to medium range airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sukhoi Superjet SSJ-100     Regional jet airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev Tu-154  Medium range airliner &lt;br&gt;&#xA;Tupolev Tu-204 &amp;amp; Tu-214     Medium range airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yakovlev Yak-42     Short range airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&lt;br&gt;&#xA;&lt;strong&gt;Once common, now mostly or all retired:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerospatiale-British Aerospace Concorde     Medium range supersonic airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Antonov An-22 Antei     Large capacity turboprop freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avions Marcel Dassault (AMD) Mercure &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BAC 111 One-Eleven -500. Short haul airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Canadair CL-44 &amp;amp; Yukon  Medium to long range airliner and freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convair 880 and 990 &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;De Havilland Comet   Medium range airliner  &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Douglas DC-6    Piston engined airliner and freighter &lt;br&gt;&#xA;Douglas DC-8-10/20/30/40/50     Medium to long range airliner and freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hawker Siddley Trident &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed 1049 Super Constellation &amp;amp; 1649 Starliner &lt;br&gt;&#xA;Lockheed L-100 Hercules     Medium range freighter &lt;br&gt;&#xA;Lockheed L-1011 TriStar 1/50/100/150/200/250    Medium to long range widebody airliner &lt;br&gt;&#xA;Lockheed L-1011 TriStar 500     Long range widebody airliner &lt;br&gt;&#xA;Lockheed L-188 Electra  Turboprop airliner and freighter &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;McDonnell Douglas DC-9-30   Short range airliners &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sud SE-210 Caravelle    Short range airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev Tu-104A Medium to long range airliner &lt;br&gt;&#xA;Tupolev TU-114  long range airliner &lt;br&gt;&#xA;Tupolev Tu-334  Short to medium range airliner prototype &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vickers VC10    Medium to long range airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&lt;br&gt;&#xA;&lt;strong&gt;These are the Boeing and Airbus planes excluded:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A300-600     Medium range widebody airliner &lt;br&gt;&#xA;Airbus A300B2/B4    Medium range widebody airliner &lt;br&gt;&#xA;Airbus A310     Medium to long range widebody airliner &lt;br&gt;&#xA;Airbus A318     100 seat regional airliner &lt;br&gt;&#xA;Airbus A319     Medium range airliner &lt;br&gt;&#xA;Airbus A320     Short to medium range airliner &lt;br&gt;&#xA;Airbus A321     Short to medium range narrowbody airliner &lt;br&gt;&#xA;Airbus A330-200     Long range widebody airliner &lt;br&gt;&#xA;Airbus A330-300     Large capacity medium to long range airliner &lt;br&gt;&#xA;Airbus A340-200/300     Long range widebody airliner &lt;br&gt;&#xA;Airbus A340-500/600     Long range widebody airliners &lt;br&gt;&#xA;Airbus A380     High capacity, long range, twindeck, widebody airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 707  Medium to long range airliner and freighter &lt;br&gt;&#xA;Boeing 717  Short to medium range airliner &lt;br&gt;&#xA;Boeing 720  Medium range narrowbody airliner &lt;br&gt;&#xA;Boeing 727  Short to medium range narrowbody airliner &lt;br&gt;&#xA;Boeing 737 Short to medium range narrowbody airliner &lt;br&gt;&#xA;Boeing 747  Long range high capacity widebody airliner &lt;br&gt;&#xA;Boeing 747SP    Long range high capacity widebody airliner &lt;br&gt;&#xA;Boeing 757 Medium range narrowbody airliner &lt;br&gt;&#xA;Boeing 767  Medium to long range widebody airliner &lt;br&gt;&#xA;Boeing 777  Long range high capacity widebody airliner &lt;br&gt;&#xA;Boeing 787-8 Dreamliner     Long range widebody airliner &lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing C-97 Stratofreighter     Freighter &lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="1897" LastEditDate="2015-04-13T09:51:49.923" LastActivityDate="2015-04-13T09:51:49.923" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14032" PostTypeId="1" AcceptedAnswerId="14047" CreationDate="2015-04-12T14:33:19.773" Score="8" ViewCount="584" Body="&lt;p&gt;Aircraft travel in well defined airways, at different flight levels depending on direction and also have specific rates of ascend, descend and turn (e.g 2-min turn).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any known models that take these spatial constraints into account and produce a plausible route between two points in space for a given aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My specific use case is straightforward: I have the current position of an aircraft and a number of alternative endpoints on that route. Instead of drawing straight lines between these alternatives, I would like to draw plausible routes taking into account as many real constraints as it is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't look into how this is implemented in computer games yet (e.g. flightgear) and I could write a simple enough auto-router taking into account the rate constraints. I would however like to know if there are any widely accepted or recommended existing auto-routing models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional Information&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In view of comments to this question I would like to clarify the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I am not looking for flight-planning algorithms or constrained&#xA;routing in the sense of optimal paths that are sometimes sought by&#xA;algorithms such as those used in &lt;a href=&quot;http://faculty.nps.edu/joroyset/docs/RoysetCarlyleWoodMOR2009_journalformat.pdf&quot; rel=&quot;noreferrer&quot;&gt;this paper&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I am looking for routing algorithms whose output is the actual path&#xA;that if set on an autopilot will bring the aircraft through an&#xA;endpoint at a specific bearing, level and speed. Ideally, I am&#xA;looking for &quot;names&quot; in the same sense that the paper linked above&#xA;states &quot;...some auto-routers for military aircraft do exist including&#xA;CLOAR, OPUS and JRAPS...&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As a secondary question, do ATC systems have some sort of&#xA;auto-routing as an aid to operators at busy areas? If yes, then&#xA;perhaps it would be worth checking if the algorithms are published&#xA;because I expect they would have to be standardised and validated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As an example, consider an aircraft that is approaching an airport to&#xA;land. The aircraft is on a specific course, flight level and speed&#xA;and it is to be directed to enter the landing pattern at a specific&#xA;point. An approach would be to extend the entry point's bearing and&#xA;aircraft's bearing and fit a cycle that corresponds to the 2-min turn&#xA;to bring the course of the aircraft on the entry point bearing (i.e.&#xA;smooth the corner of the intersection). If such an intersection is&#xA;undefined (e.g. the bearings are parallel, or they intersect at a&#xA;really long distance) then a new leg needs to be added which a)&#xA;intersects with the current course of the aircraft b) intersects the&#xA;entry point bearing and c) satisfies other constraint (e.g. shortest&#xA;distance, no sharp angles, etc). If that is undefined on the side of&#xA;the entry point a new leg must be added, this leg should a) intersect the given leg at...and so on. &#xA;This approach will result to a path (not THE path) that respects specific&#xA;constraints...But obviously the question here is how realistic it&#xA;will be both for an aircraft to fly but also would a human operator&#xA;produce a path with similar qualities or reject it altogether? Hence,&#xA;the question...are there any auto-router algorithms out there&#xA;already?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;5&quot;&gt;&#xA;&lt;li&gt;If the general consensus veers more towards a situation where it is very hard to get acurate information on routing models for civilian aircraft, is there a set of minimal parameters that would have to be taken into account when designing a simplistic auto-router that would be more likely to generate plausible paths given two points in space? &quot;Plausible&quot; is defined as &quot;similar to what a human ATC would have directed the airplane to do&quot; or &quot;a path that appears sensible to an average pilot&quot;. At the moment I would be considering the rates of ascend, descend and turn.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="4181" LastEditorUserId="4181" LastEditDate="2015-04-13T16:23:12.850" LastActivityDate="2017-02-11T21:56:18.983" Title="Are there any widely applicable models for plausible aircraft auto-routing?" Tags="&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;navigation&gt;&lt;airspace&gt;&lt;flight-path&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14033" PostTypeId="1" AcceptedAnswerId="14087" CreationDate="2015-04-12T15:53:46.470" Score="9" ViewCount="2799" Body="&lt;p&gt;The Cessna 172 and Piper Warrior are similar in many ways, including their engines: for most of their production history (1968-1998 for the 172; the entire history for the Warrior) both were equipped with a Lycoming O-320 engine of 150 or 160 horsepower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One significant difference between the two is in their before-landing checklists: the 172 instructs the pilot to turn carburetor heat on before closing the throttle (&lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;p. 4-19&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Carburetor heat should be applied prior to any significant reduction or closing of the throttle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Conversely, the Warrior recommends carburetor heat &quot;if required&quot;, and even recommends against it unless necessary (&lt;a href=&quot;http://flugschulebasel.ch/content/dam/fsb/fleet/poh/Warrior%20II%20Manual.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;p. 4-23&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be critical in case of a go-around. Full throttle operation with carburetor heat on can cause &lt;a href=&quot;https://aviation.stackexchange.com/q/14038/136&quot;&gt;detonation&lt;/a&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Considering that these two aircraft have very similar engines, what would explain such a drastically different approach to the potential danger of carburetor icing?&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-06-02T21:21:22.530" Title="How does aircraft design affect carburetor ice?" Tags="&lt;aircraft-design&gt;&lt;piston-engine&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14034" PostTypeId="1" AcceptedAnswerId="14035" CreationDate="2015-04-12T16:43:25.713" Score="27" ViewCount="99732" Body="&lt;p&gt;I found a data source, where Boeing 737 could be encoded with the following values - &lt;code&gt;733&lt;/code&gt;, &lt;code&gt;734&lt;/code&gt;, &lt;code&gt;735&lt;/code&gt;, &lt;code&gt;738&lt;/code&gt;, &lt;code&gt;73G&lt;/code&gt;, and &lt;code&gt;73H&lt;/code&gt;; Boeing 767 with values &lt;code&gt;762&lt;/code&gt;, &lt;code&gt;763&lt;/code&gt;; Boeing 777 - &lt;code&gt;772&lt;/code&gt;, &lt;code&gt;773&lt;/code&gt;, &lt;code&gt;777&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea why such coding is used? Is it some standard to encode them with such values? Can I get more details from such codes (for ex., full aircraft type incl. customer code like &lt;code&gt;Boeing 737-808&lt;/code&gt;)?&lt;/p&gt;&#xA;" OwnerUserId="2421" LastActivityDate="2019-12-11T08:19:24.843" Title="What is the difference between Boeing 73G, 73H and 737?" Tags="&lt;boeing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14035" PostTypeId="2" ParentId="14034" CreationDate="2015-04-12T17:20:09.713" Score="34" Body="&lt;p&gt;There are two main systems of aircraft type designations: IATA and ICAO codes. The ones you mention are IATA codes (all 3-character) and are often used for shortened aircraft type designation in public information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both code types are &lt;a href=&quot;http://www.airlinecodes.co.uk/arctypes.asp&quot; rel=&quot;noreferrer&quot;&gt;listed here with the corresponding full aircraft types&lt;/a&gt;. As you can see, the IATA information covers the type and variant, including some features such as winglets, but not necessarily extended range models or sub-variants with different engines. It also differentiates between freighters and passenger versions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Despite the additional digit, ICAO codes are less precise and often include several variants such as freighter as well as passenger variants of the same type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The codes given in your question translate to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;733&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;3&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;734&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;4&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;735&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;5&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;738&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;8&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;73G&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;7&lt;/strong&gt;00 (7th letter of the alphabet)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;73H&lt;/strong&gt;  - Boeing &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;8&lt;/strong&gt;00 with winglets (8th letter of the alphabet)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;762&lt;/strong&gt;  - Boeing &lt;strong&gt;76&lt;/strong&gt;7-&lt;strong&gt;2&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;763&lt;/strong&gt;  - Boeing &lt;strong&gt;76&lt;/strong&gt;7-&lt;strong&gt;3&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;772&lt;/strong&gt;  - Boeing &lt;strong&gt;77&lt;/strong&gt;7-&lt;strong&gt;2&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;773&lt;/strong&gt;  - Boeing &lt;strong&gt;77&lt;/strong&gt;7-&lt;strong&gt;3&lt;/strong&gt;00&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;777&lt;/strong&gt;  - ambiguous &lt;strong&gt;777&lt;/strong&gt; type&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(all passenger aircraft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, as @Ralph J mentions, it's not always clear which type of code is used. Mostly, a 4-digit-code will be an ICAO code and a 3-character-code will use the IATA system, but because some ICAO codes only contain 3 digits, this isn't always reliable. For example, if you read &quot;DC6&quot;, it could be the IATA code and refer to the passenger version, or it could be the ICAO code and you wouldn't know if it refers to the passenger or the freighter version.&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="5665" LastEditDate="2016-02-17T11:19:26.653" LastActivityDate="2016-02-17T11:19:26.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14036" PostTypeId="2" ParentId="14034" CreationDate="2015-04-12T17:33:45.980" Score="31" Body="&lt;ul&gt;&#xA;&lt;li&gt;The &quot;733&quot; is the &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;3&lt;/strong&gt;00. &lt;/li&gt;&#xA;&lt;li&gt;The &quot;734&quot; is the &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;4&lt;/strong&gt;00.&lt;/li&gt;&#xA;&lt;li&gt;The &quot;735&quot; is the &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;5&lt;/strong&gt;00.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Then there is the 737-700, which would, by that convention, translate to the &quot;737&quot;.  But that's the general type, the 737 that encompasses all of the variants.  So you can foresee plenty of confusion if sometimes &quot;737&quot; means the Boeing 737, and other times &quot;737&quot; is short for the particular 737-700 variant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to avoid that confusion, they took the 7th letter of the alphabet, G, and used that instead of the &quot;7&quot; of &quot;-700&quot; and so now:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &quot;73G&quot; is the &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;7&lt;/strong&gt;00.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the sake of consistency, they did the some thing with the 737-800, and in some places you'll see that referred to as the &quot;73H&quot; -- as the 737-700 is followed by the 737-800, the 73G is followed by the 73H.  But in other contexts, you'll see the reference revert to the old convention, and&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &quot;738&quot; &lt;em&gt;and&lt;/em&gt; &quot;73H&quot; refer to the &lt;strong&gt;73&lt;/strong&gt;7-&lt;strong&gt;8&lt;/strong&gt;00.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The link in @JulianHzg's answer specifies which codes are used in IATA and which in ICAO usage, although sometimes you'll see a code in isolation without necessarily knowing which system of reference it's coming from.  In a pure, strict ICAO framework, the &quot;B737&quot; is ONLY the 737-700, with winglets, in a passenger configuration, but you'll see that used in places that aren't quite as strict in their conventions, and &quot;73G&quot; avoids confusion.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-12T17:33:45.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14038" PostTypeId="1" AcceptedAnswerId="14039" CreationDate="2015-04-12T20:48:28.307" Score="24" ViewCount="21293" Body="&lt;p&gt;Recently, I saw &lt;a href=&quot;https://aviation.stackexchange.com/q/14033/3170&quot;&gt;this question&lt;/a&gt;, which included a rather alarming quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Full throttle operation with carburetor heat on can cause detonation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Woah! That doesn't sound good. In fact, I would have figured aviation engine manufacturers would have worked hard to prevent their engines from exploding, and possibly destroying the rest of the aircraft and/or killing the pilot in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also found &lt;a href=&quot;https://aviation.stackexchange.com/q/2141/3170&quot;&gt;this question&lt;/a&gt;, with a rather calm quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What if I have a noise cancelling headset on, and the engine undergoes detonation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems like there should be other cues that your engine just blew itself to bits...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm figuring that perhaps &quot;detonation&quot; in this context doesn't &lt;em&gt;actually&lt;/em&gt; mean that your engine block turns into shrapnel. I also figure that it doesn't refer to the normal process of piston engines, where fuel is injected and mixed with fuel before detonating. So what &lt;em&gt;does&lt;/em&gt; it mean?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-13T07:25:35.070" Title="What is &quot;detonation&quot; in a piston engine?" Tags="&lt;piston-engine&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14039" PostTypeId="2" ParentId="14038" CreationDate="2015-04-12T22:32:15.093" Score="31" Body="&lt;p&gt;Detonation, as the name suggests, is an explosion of the fuel-air mixture inside the cylinder. Under normal operation, the spark plugs each ignite a point in the fuel/air charge, which then propagate through the cylinder and provides a consistent, regulated burn in a process called &lt;a href=&quot;http://en.wikipedia.org/wiki/Deflagration&quot; rel=&quot;noreferrer&quot;&gt;deflagration&lt;/a&gt;. This extends the time that the burning fuel pushes on the cylinder, providing a gentle power stroke.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During detonation, the fuel/air charge (or pockets within the charge) explodes rather than burning smoothly. Because of this explosion, the charge exerts a much higher force on the piston and cylinder, leading to increased noise, vibration, and cylinder head temperatures. The violence of detonation also causes a reduction in power. Mild detonation may increase engine wear, though some engines can operate with mild detonation regularly. However, severe detonation can cause engine failure in minutes. Because of the noise that it makes, detonation is called &quot;engine knock&quot; or &quot;pinging&quot; in cars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bkkpm.png&quot; alt=&quot;Visualization of Detonation. Source: FAA PHAK, page 6-18&quot;&gt;&lt;br/&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2006.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA PHAK&lt;/a&gt;, page 6-18)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detonation can be caused by a number of factors, but generally they relate to a situation outside of the engine's design. Using the wrong fuel can cause detonation: the octane rating of a fuel is basically the amount of pressure it can take before it detonates. Similarly, high cylinder temperatures can cause detonation(1). This is why mixture is set very rich when at high power levels: the excess fuel cools the cylinders, preventing detonation. As noted above, full power with carburetor heat on can cause detonation, as the increased temperature mimics the effect of high cylinder temperatures. Full carburetor heat is required to provide at least a 90 degree F increase in intake air temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further reading:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Page 6-19 of the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2006.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;An &lt;a href=&quot;https://www.savvyanalysis.com/articles/detonation-and-pre-ignition&quot; rel=&quot;noreferrer&quot;&gt;article&lt;/a&gt; at Savvy Analysis&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;1) Detonation is distinct from pre-ignition, where the fuel/air charge is ignited by something other than the spark plug. Notably, detonation and pre-ignition often cause each other, as a detonating engine will have a very high CHT (potentially enough to cause pre-ignition), and if the charge pre-ignites as the cylinder is still rising, the continued compression may cause the charge to detonate.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2015-04-14T13:49:12.323" LastActivityDate="2015-04-14T13:49:12.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14040" PostTypeId="1" CreationDate="2015-04-12T22:32:44.873" Score="1" ViewCount="1127" Body="&lt;p&gt;When in normal Law are Airbus aircraft now protected from the types of excessive rudder input that caused the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot; rel=&quot;nofollow&quot;&gt;American Airlines 587&lt;/a&gt; (as dramatized in Mayday, S13E05)?&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="3170" LastEditDate="2015-04-12T22:41:12.207" LastActivityDate="2015-04-13T07:22:11.833" Title="Are modern Airbus aircraft protected from excessive rudder input?" Tags="&lt;airbus&gt;&lt;rudder&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14041" PostTypeId="2" ParentId="14033" CreationDate="2015-04-12T23:32:57.983" Score="0" Body="&lt;p&gt;Carby heat should be used on final (and any other significant idle or near idle descent) until you reach around 300 fleet AGL to prevent icing. It should then be turned off during the final part of your approach so that you'll have full power available in case you need to execute a go around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think what you've found is not a difference in engine design, but a difference in wording in the respective manuals. The Cessna handbook states that heat should be applied during any significant closing of throttle, which is correct (as presumably you'll also be descending shortly after closing throttle), but it should also be turned off prior to touching down in case you need to rapidly apply full throttle for go around, as per the Warrior manual.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-04-12T23:32:57.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14042" PostTypeId="2" ParentId="14027" CreationDate="2015-04-12T23:36:42.123" Score="1" Body="&lt;p&gt;&lt;strong&gt;Regarding question 2:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no tactile or visual feedback (i.e. no sidestick movement when autopilot engaged). There may be visual cues on Airbus aircraft from the Side Stick Priority lights in front of each pilot on the glareshield. There is also an aural warning if sidestick priority is taken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Regarding question 3:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next generation of sidestick controls for fly-by-wire commercial aircraft are called Active Sidesticks and will provide visual and tactile feedback. They can already be found on the Gulfstream G500 and G600 aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationweek.com/technology/active-sidestick-controls-make-commercial-debut&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; from &lt;em&gt;Aviation Week &amp;amp; Space Technology&lt;/em&gt; provides details.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2015-04-13T05:29:19.733" LastActivityDate="2015-04-13T05:29:19.733" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14044" PostTypeId="2" ParentId="14034" CreationDate="2015-04-13T04:53:42.487" Score="11" Body="&lt;p&gt;While the existing answers cover the most common uses of such codes (ICAO and IATA codes,) in order to further complicate things, there is actually a third possible meaning, as well. Airlines often assign a letter designator in order to specify a particular &lt;strong&gt;cabin configuration&lt;/strong&gt;. For example, &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Delta has no less than 9 unique codes for its 757-200&lt;/a&gt; cabin layouts, even though they're all exactly the same airframe. If you're looking at a website like &lt;a href=&quot;http://www.seatguru.com/airlines/Delta_Airlines/information.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;SeatGuru&lt;/a&gt; (or the website of the airline itself,) these are the codes you'll see in reference to exactly which cabin configuration will be on the particular flight you're booking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A given seat number may refer to a completely different seat or even not exist at all from one cabin configuration to another, even on the same type of airframe on the same airline, so these codes are used to disambiguate the configuration. Unfortunately, this also has the result of making the code itself even more ambiguous in the absence of context indicating which type of code it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this type of code doesn't mean much to the pilot, it can mean a lot to the passengers. To go back to the Delta 757-200 example, on the &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-757-200-75a.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;75A configuration&lt;/a&gt;, seat 2A is a normal First Class seat with 40&quot; seat pitch. On the &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-757-200-75s.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;75S configuration&lt;/a&gt;, on the other hand, it's a 76-inch-long flat-bed seat. Slight difference there. While the differences in economy usually aren't quite as dramatic, they can still be rather large. For instance, on the &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-757-200-75s.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;75S configuration&lt;/a&gt;, seat 19F has a lot of extra leg room due to a missing seat in front because of an exit door, whereas it's just a normal economy seat on the &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/boeing-757-200-75a.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;75A configuration&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, this code is distinct from the customer codes &lt;a href=&quot;https://aviation.stackexchange.com/q/8379/755&quot;&gt;discussed in this question&lt;/a&gt;, which would instead take the form of 757-232 for a 757-200 delivered to Delta Airlines. The code discussed in this answer denotes the current cabin configuration of the aircraft and takes the same form as the ICAO/IATA codes, whereas the code discussed in the other question denotes the customer who originally ordered the aircraft from the manufacturer. So, while all 757-200s initially delivered to Delta Airlines would be 757-232s, they can (and do) have many different cabin configurations, each with their own code of the form 75A, 75S, 75Z, etc.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-04-13T14:08:02.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14045" PostTypeId="2" ParentId="14027" CreationDate="2015-04-13T07:14:26.640" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Sidesticks are smaller than yokes. To apply a control input one only needs to turn one's wrist while a yoke requires you to use both of your arms to make the big aircraft turn.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Side-sticks are used together with control laws. In an Airbus Normal Law (and Alternate Law which differs only by not providing the flight envelope protections), the system automatically trims for 1 G wing loading (which equals constant flight path angle) and zero roll rate and the side-stick deflection commands wing loading in pitch and roll rate in roll. The springs are sufficient to provide &lt;em&gt;all feedback there is to provide&lt;/em&gt; as the deflection and the force both correspond to the command given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the way side-sticks work, extended deflection is rarely necessary, nor are very fine adjustments normally needed to stabilize the plane on desired flight path, because the computer handles that.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Secondly, and this is the major question, as it appears, the sidesticks make it much harder, to be aware of the currently applied control input (especially) for the other pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Feedback, on any kind of control, is provided by position and force. The other pilot can only feel the position. This allows them to notice that the other pilot pulled up, but &lt;em&gt;not&lt;/em&gt; whether it is dangerously close to stall, because the stick position is biased by aircraft balance and, if horizontal stabilizer is used for trim (which all airliners do), also by trim. So the information it provides is rather limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Airbus the side-sticks are not connected, so even this limited information is not available. But they have an advantage too. If the pilot flying is incapacitated or confused, the pilot monitoring can push a “control priority” button on the side-stick and the computer then only responds to their side-stick, so they don't have to fight with the other pilot on the controls.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How is the general assessment of those sidesticks concerning safety?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've not seen any specific study. But they were approved and I am not aware of any accident on Airbus where similar accident wouldn't have happened with other type with traditional control column.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there any feedback to the pilots which stick is giving what input?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If both side-sticks are giving input, there is aural and visual warning “dual input”. If one pilot presses the “control priority” button, there is an announcement “control priority left/right” and visual indication. There is no direct indication of what the command is, but the pilots are looking for what the plane is doing anyway and they can usually judge from that. There is also indicator of control surface positions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Has there been any development in improving this situation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am not aware of any aviation authority thinking there is a problem to fix. Manufacturers are coming up with new schemes they consider good, but that may be as much marketing as genuine improvement.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the accidents/incidents sidesticks more or less contributed to confusion/lack of information?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can't think of any where it could be said the situation would have been significantly better if the controls were linked. If both pilots are confused, the connection would not help much and if only one is confused, the other can use the control priority to take over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even AF447, where some dual input was involved, is not really unique. There have been several crashes where pilots didn't realize a stall and didn't attempt recovery all the way from cruise level down to the ground (&lt;a href=&quot;http://avherald.com/h?article=477c75de&quot; rel=&quot;nofollow&quot;&gt;the most recent one&lt;/a&gt;) and all the others happened in planes with mechanically connected control column.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-04-13T16:05:32.087" LastActivityDate="2015-04-13T16:05:32.087" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14046" PostTypeId="2" ParentId="14040" CreationDate="2015-04-13T07:22:11.833" Score="2" Body="&lt;p&gt;Yes, A320 and all newer models have rudder travel limiter that limits the maximum rudder deflection depending on speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted, that this has &lt;em&gt;nothing&lt;/em&gt; to do with normal law. Normal law governs pitch and roll. Rudder is controlled by &lt;em&gt;(hydro)mechanically connected&lt;/em&gt;¹ pedals and yaw damper, which is independent from the system controlling pitch and roll and simply reacts to side-slip (lateral acceleration actually, only A350 will have side-slip vanes) induced by the roll.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Different Airbus models have different subset of controls with direct hydromechanical link as a backup in case of electric failure, so I am not sure rudder pedals have it on all models. They do on A320.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-04-13T07:22:11.833" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14047" PostTypeId="2" ParentId="14032" CreationDate="2015-04-13T09:47:15.940" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I am looking for routing algorithms whose output is the actual path that if set on an autopilot will bring the aircraft through an endpoint at a specific bearing, level and speed&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are indeed models for moving between waypoints: I remember siting on the flightdeck of an A320 and noticing the airspeed increase as we descended towards the airport. I asked the pilot and he responded that this was in preparation for a turn coming up as to not loose airspeed. Not a huge differences perhaps but will make a difference over a year with a lot of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airlines have &lt;em&gt;company routes&lt;/em&gt; detailing which waypoints to use to a destination. To the best of my knowledge, these are fairly standard (you might have  few) and not too weather dependant, unless there is a big storm for instance. One exception to this are transatlantic tracks that are changed daily depending on weather. At least for most flights, possible variations are few and will be in busy airways. Changing airways is normally a larger deviation so it is just good to bare with it, and the weather is unlikely to be considerably better for just a slight detour.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As a secondary question, do ATC systems have some sort of auto-routing as an aid to operators at busy areas?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ATC have normally no real incentive to cut down routes, at least in cruise. They might help you skip some waypoints and get the aircraft down a little quicker if the airspace is calm during arrival. To also put things into perspective, I was on the flightdeck into a moderately large european airport where we were put first into a hold due to bad planning and then told to speed up after we left it to catch up again. Arlanda airport had something going on however with &lt;a href=&quot;http://www.swedavia.com/arlanda/about-stockholm-arlanda-airport-/about-stockholm-arlanda-airport/environment/carbon-dioxide-emissions/air-traffic-/green-approaches/&quot; rel=&quot;nofollow&quot;&gt;green approaches&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I am looking for routing algorithms whose output is the actual path that if set on an autopilot will bring the aircraft through an endpoint at a specific bearing, level and speed. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The issue here is that there is no incentive for aircraft manufacturers to release such algorithms to the public. If Airbus uses algorithm A, and Boeing algorithm B, each with a different inputs, you neither would want the other to make algorithm C that works with both inputs and being more efficient. The bottom line however is that everybody remains constrained by the infrastructure already in place that is pretty rigid. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-04-13T10:20:19.150" LastActivityDate="2015-04-13T10:20:19.150" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14048" PostTypeId="2" ParentId="14018" CreationDate="2015-04-13T12:16:46.257" Score="9" Body="&lt;p&gt;Excerpt from the FAA Publication &quot;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_1.pdf&quot;&gt;Instrument Procedures Handbook&lt;/a&gt;&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Standard taxi routes improve ground management at highdensity&#xA;  airports, namely those that have airline service. At&#xA;  these airports, typical taxiway traffic patterns used to move&#xA;  aircraft between gate and runway are laid out and coded.&#xA;  The ATC specialist (ATCS) can reduce radio communication&#xA;  time and eliminate taxi instruction misinterpretation by&#xA;  simply clearing the pilot to taxi via a specific, named route.&#xA;  An example of this would be Los Angeles International&#xA;  Airport (KLAX), where North Route is used to transition&#xA;  to Runway 24L. [Figure 1-7] These routes are issued by&#xA;  ground control, and if unable to comply, pilots must&#xA;  advise ground control on initial contact. If for any reason&#xA;  the pilot becomes uncertain as to the correct taxi route, a&#xA;  request should be made for progressive taxi instructions.&#xA;  These step-by-step routing directions are also issued if the&#xA;  controller deems it necessary due to traffic, closed taxiways,&#xA;  airport construction, etc. It is the pilot’s responsibility to&#xA;  know if a particular airport has preplanned taxi routes, to&#xA;  be familiar with them, and to have the taxi descriptions&#xA;  in their possession. Specific information about airports&#xA;  that use coded taxiway routes is included in the Notice to&#xA;  Airmen Publication (NTAP).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;NTAP can be found on: &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/notices/&quot;&gt;https://www.faa.gov/air_traffic/publications/notices/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the time of writing the KLAX North Route example can be found on page 4-SW-11, and reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;North Route&lt;/strong&gt;&#xA;  Taxi towards taxilane Sierra (S) taxi northbound on taxilane Sierra (S), and at Check-point-1 contact Ground&#xA;  Control on frequency 121.65, hold short of taxiway Delta (D).&#xA;  Taxilane Sierra (S) is not visible from the ATCT&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's also &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/7110.116.pdf&quot;&gt;FAA Advisory Circular 7110.116&lt;/a&gt; regulating Standard Taxi Routes (STR's) as bilateral agreements (LOA's - Letter of Agreement) between each ATC unit and their users (airlines). The document contains information on what the LOA needs to contain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of the US, standard taxi instructions, if any, could be expected to be found in the AD-section (Aerodromes) of that respective country's AIP (Aeronautical Information Publication).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an airline pilot, this information might be integrated into your company's nav data solution, ie. information about standard taxi routes available to you would be written/drawn out bundled with your airport diagrams etc.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-04-13T12:22:16.273" LastActivityDate="2015-04-13T12:22:16.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14049" PostTypeId="1" AcceptedAnswerId="14050" CreationDate="2015-04-13T14:27:06.827" Score="3" ViewCount="531" Body="&lt;p&gt;Mimiron's head is an endgame raid reward from the game World of Warcraft that's basically a cup with an upwards rotor mounted on the rear and 2 side rotors pointed downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/RfUHMBG4S6U?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; is a video which shows what it looks like. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/vAX1mWLWXHo?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; shows it flying around with a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Flying Machine, and the upgraded version Turbo-Charged Flying Machine, is a mount that a player can create themselves using the Engineering profession. It looks more like a traditional helicopter, but instead of a rear-mounted rotor, it has an engine with a propeller on each side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/MH8jA9OUbkQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; shows the Turbo-charged Flying Machine flying around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;now, to me as an aviation-illiterate person, it looks like as-is, either mount could not quite work in the real world, but if you made some modifications, they could work. Is this true? Could you make these helicopter-like vehicles work in the real world? Assume current technology or immediate-future technology (available in the next 5 years).&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="1823" LastEditDate="2017-05-23T07:54:40.520" LastActivityDate="2019-08-10T03:05:04.587" Title="Could &quot;Mimiron's Head&quot; or &quot;flying machine&quot; fly in the real world?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14050" PostTypeId="2" ParentId="14049" CreationDate="2015-04-13T16:01:46.173" Score="6" Body="&lt;p&gt;Could they fly... ...Maybe &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second device looks quite a bit like an &lt;a href=&quot;http://en.wikipedia.org/wiki/Autogyro&quot; rel=&quot;noreferrer&quot;&gt;Auto Gyro&lt;/a&gt; which is very much capable of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first device looks like (as has been mentioned) the center of gravity would be an issue. If those side pods generated enough thrust along with the main rotor you could get it off the ground however I would think it would be very hard to control. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-13T16:01:46.173" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14051" PostTypeId="2" ParentId="14032" CreationDate="2015-04-13T17:23:44.380" Score="1" Body="&lt;p&gt;Both &lt;a href=&quot;http://blog.foreflight.com/2015/03/19/faster-auto-router-now-available-duats-services-deprecated/&quot; rel=&quot;nofollow&quot;&gt;ForeFlight&lt;/a&gt; and DUATS provide airway auto-routing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the comments in your question, I suspect this is not what you want, but I'm offering it as an answer just in case.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-04-13T17:23:44.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14054" PostTypeId="1" AcceptedAnswerId="14055" CreationDate="2015-04-13T23:55:32.133" Score="6" ViewCount="1030" Body="&lt;p&gt;How do airports generate &quot;indirect&quot; income i.e. income from things other than aviation operations (landing, FBO services, repairs)?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="3825" LastEditDate="2015-04-15T02:20:00.343" LastActivityDate="2015-04-22T14:04:13.497" Title="How do airports generate &quot;indirect&quot; income?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14055" PostTypeId="2" ParentId="14054" CreationDate="2015-04-14T02:34:56.407" Score="18" Body="&lt;p&gt;One way to approach this question is to look at the annual budget for an airport. I'm going to assume that you mean a large passenger airport as opposed to one focused on serving general aviation, cargo, etc... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's use SFO (San Francisco International) as our example. It's a city-owned airport, so the budget is a public document. Here's &lt;a href=&quot;http://media.flysfo.com/media/sfo/about-sfo/annual-operating-budget-fy1415-fy1516.pdf&quot;&gt;the budget for FY2014/15 and FY2015/16&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Page 5 (page 7 in the PDF) breaks down major sources of revenue. We have some that fall into the category of &quot;direct&quot; revenue in your question: landing fees, terminal rentals, etc... under the &quot;aviation&quot; category. Some of the terminal rental fees include space for purposes you might not consider aviation uses, like back offices for airline staff We also have $60-80M in &quot;PFC Revenue.&quot; PFC stands for &lt;a href=&quot;https://en.wikipedia.org/wiki/Airport_improvement_fee&quot;&gt;&quot;Passenger Facility Charge&quot;&lt;/a&gt;; it's a charge that is added to the ticket price of everyone flying out of that airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, there are the non-aviation revenues. The bulk of those come in two categories: parking and concessions. Parking is self-explanatory. Concessions describes all the independent businesses that operate at the airport. Many businesses lease terminal space for retail shops (including duty-free), restaurants and take-out food, lounges, currency exchange, etc... They all pay rent and/or a share of revenue to the airport based on the terms of their lease. SFO also books about $23M/year in revenue off the sale of electricity, as the airport sells electricity to its tenants (airlines, concessions, etc...). I suspect, but am not positive, that these electricity sales are a nice moneymaker for the airport, as it can purchase hydropower from the City at extremely low cost and resell it at market (utility company) rates to its tenants. This is a quirk particular to San Francisco however. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you scroll through the detailed budget in the PDF, you'll find entries for other revenue categories. Examples include advertising fees (Clear Channel pays the airport to put up ads in the terminals and other areas), revenue for things like ATMs and baggage carts, leases to rental car companies, fees paid by taxicabs and airport buses for the right to access airport property, and even permit fees paid by filmmakers and photographers using the airport. Heck, the airport even charges the regional transit agency $3.2M/year in rent and custodial fees for the airport train station. Browsing through the budget should give you a pretty good idea where a large US airport can make money from non-aviation services. &lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2015-04-14T02:34:56.407" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14057" PostTypeId="2" ParentId="1913" CreationDate="2015-04-14T07:24:00.373" Score="4" Body="&lt;p&gt;Yes you can. Yes it has been done. And yes people are still doing it. The caveat being that most (all?) of the tests are done with scale models rather than full size planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Free flight wind tunnel tests are done for different reasons from static mounted tests. Where static mounted tests are done to collect measurements of forces acting on the aircraft/part, free flight tests are done to understand/confirm the stability of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a model plane in such confined spaces is very difficult and typically the plane will tend to wander around in the wind tunnel. As such, the data that you can get from a free flight test is very limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the difficulties of doing the test and the limited amount of data you can get from it most new plane designs don't go through such a test. Instead, what typically happens is that the design goes straight to a radio controlled scale model that is flown outdoors to study its stability. However, when trying out new ideas that has not been developed it is still worth doing the stability tests in a controlled environment - in a large wind tunnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some old videos of free flight wind tunnel tests (these come from a time period where the behavior of delta wings were not yet fully understood):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=OGmigdhxMRw&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=OGmigdhxMRw&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=aDIQc3-umf4&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=aDIQc3-umf4&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a more recent video of a free flight wind tunnel test of the Blended Wing Body:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=B7zMkptajMQ&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=B7zMkptajMQ&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-04-14T07:24:00.373" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14059" PostTypeId="1" AcceptedAnswerId="14060" CreationDate="2015-04-14T12:41:54.427" Score="13" ViewCount="4763" Body="&lt;p&gt;Look at this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TkBl2.jpg&quot; alt=&quot;strange plane&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust force from the engine should generate some clockwise moment, right? Why won't it turn and just crash then? I guess the wings generate some sort of anti-clockwise moment? Can someone explain this?&lt;/p&gt;&#xA;" OwnerUserId="8127" LastEditorUserId="1467" LastEditDate="2015-04-14T17:59:32.447" LastActivityDate="2015-04-14T20:57:58.800" Title="Can someone explain to me why these planes just don't turn about their center of gravity?" Tags="&lt;engine&gt;&lt;aircraft-physics&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14060" PostTypeId="2" ParentId="14059" CreationDate="2015-04-14T12:53:59.823" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The thrust force from the engine should generate some clockwise moment, right?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If we take your photo as a reference (and thus we intend &quot;clockwise in the picture plane&quot;), yes, it is. It is called &lt;strong&gt;pitch&lt;/strong&gt; moment, because it would change the pitch of the aircraft (in your case, a &lt;a href=&quot;http://en.wikipedia.org/wiki/A-90_Orlyonok&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-90_Orlyonok&lt;/a&gt;), and in the case shown in your picture is negative, because it would make the aircraft pitch down.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why wont it turn and just crash then? I guess the wings generate some sort of anti clock wise moment? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because the wings &lt;em&gt;and the horizontal stabilizer&lt;/em&gt; produce a total net pitch moment that counteracts the one generated by the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They do so by having the center of lift in a different location w.r.t. the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The &quot;normal&quot; configuration for airliners would have an opposite pitch moment due to the engines, since in that case the engines are usually below the wings (and, being usually low wings, below the center of gravity). It is well illustrated in this image &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=2&amp;amp;LLID=64&amp;amp;LLTypeID=2&quot; rel=&quot;nofollow noreferrer&quot;&gt;taken from the FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ol94G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-04-14T14:33:01.233" LastActivityDate="2015-04-14T14:33:01.233" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14062" PostTypeId="2" ParentId="14059" CreationDate="2015-04-14T17:43:34.453" Score="7" Body="&lt;p&gt;If you look closely there are two propellers on the tail, and they are contra-rotating, so one spins clockwise and the other counterclockwise so there is no roll moment produced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See: &lt;a href=&quot;http://en.wikipedia.org/wiki/A-90_Orlyonok&quot; rel=&quot;noreferrer&quot;&gt;http://en.wikipedia.org/wiki/A-90_Orlyonok&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8131" LastEditorUserId="8136" LastEditDate="2015-04-14T20:57:58.800" LastActivityDate="2015-04-14T20:57:58.800" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14063" PostTypeId="2" ParentId="14059" CreationDate="2015-04-14T19:18:41.490" Score="4" Body="&lt;p&gt;There are also engines in the nose with their exhaust pointing below the leading edge of the wing.  Although, according to wikipedia, these engines can be turned off during cruise, when on, these engines would provide a pitching moment to counteract the nose-down pitching moment from the turboprop.&lt;/p&gt;&#xA;" OwnerUserId="8134" LastActivityDate="2015-04-14T19:18:41.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14064" PostTypeId="2" ParentId="14059" CreationDate="2015-04-14T20:39:03.850" Score="4" Body="&lt;p&gt;No matter the exact design and careful balancing that goes into an aircraft, there is no general guarantee that all the moments cancel out. The direction and magnitude of pitch/roll/yaw moments vary with speed and altitude. Aircraft typically require active control surface inputs to stay level; these inputs can be re-centered or &quot;trimmed&quot; using &lt;a href=&quot;http://en.wikipedia.org/wiki/Trim_tab&quot; rel=&quot;nofollow&quot;&gt;trim tabs&lt;/a&gt; (which are usually located on the trailing edges of the control surfaces) so the pilot doesn't have to actively run the inputs.&lt;/p&gt;&#xA;" OwnerUserId="8137" LastEditorUserId="755" LastEditDate="2015-04-14T20:50:27.727" LastActivityDate="2015-04-14T20:50:27.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14065" PostTypeId="2" ParentId="2361" CreationDate="2015-04-14T20:41:26.137" Score="13" Body="&lt;p&gt;On newer airliners it is fed into a septic tank. Decades ago, it was simply dropped overboard. &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_lavatory&quot;&gt;Before the introduction of vacuum flush toilets&lt;/a&gt;, water flushing was used which involved big tanks which could leak their content overboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.nytimes.com/1990/01/05/us/jet-lands-after-an-engine-drops-off.html&quot;&gt;Boeing 727 had at least two cases where the right engine was lost as the ultimate consequence of this malfunction&lt;/a&gt;. Since the lavatory piping was on the right side, ice which had built up there could break loose and be ingested by the engine behind. If the ice block was large enough, it could damage the fan, and the resulting imbalance could shake the engine off. Boeing engineers designed the engine mount with a rated break point so hefty engine vibrations would not damage the rest of the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glider pilots have all kinds of means to lighten themselves when nature calls. The product of this is then thrown overboard - that is what the small sliding window on the left side of a glider canopy is for. A friend of mine uses plastic bags and once forgot to take one with him in a competition flight. He realized his omission just before he was aero-towed on his way and asked bystanders for help. Someone handed him his plastic bag which had been used to hold apples - and was perforated. My friend realized this detail too late, but very soon after he began using the bag.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-14T21:13:10.870" LastActivityDate="2015-04-14T21:13:10.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14066" PostTypeId="1" CreationDate="2015-04-14T22:28:37.500" Score="3" ViewCount="381" Body="&lt;p&gt;I'm from Mexico but worked in San Francisco for 4 years under a TN Visa. During that time I learned how to fly and obtained a PPL and then an IFR rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm now living in Boston getting a Masters Degree under an F1 Visa. I'm interested in flying into Canada. Canada requires visas for Mexican citizens, but a friend claims that there's an exception for pilots. I only want to check out Montreal, so I would be in Canada for 48-72 hours max.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's a good resource to see visa requirements for pilots from different countries flying into countries other than their own?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="8139" LastEditorUserId="3170" LastEditDate="2015-04-15T01:18:26.757" LastActivityDate="2015-04-17T18:58:45.903" Title="Does a Mexican citizen studying in the US with an FAA license need a visa when landing at airports in Canada?" Tags="&lt;usa&gt;&lt;international&gt;&lt;canada&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14067" PostTypeId="2" ParentId="7755" CreationDate="2015-04-14T22:45:33.737" Score="5" Body="&lt;p&gt;I obtained 100% on my Private Pilot Airplane Single Engine Land (ASEL) test in the US. My instructor didn't need to provide an additional endorsement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, upon seeing my score, the Designated Pilot Examiner (DPE) was especially tough. After a hard grilling, she admitted to me: &quot;I wanted to go hard on you because 100% on your FAA test doesn't mean you know everything you need to be a safe pilot. The license you just got is a license to learn, with flying privileges - don't ever forget that.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have taken that lesson home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I took the IFR FAA test, I purposely missed a question on a subject I was particularly strong in and got a 98%. When the DPE (a different one) asked me questions on the subject, he was pleased I understood the concepts very well.&lt;/p&gt;&#xA;" OwnerUserId="8139" LastActivityDate="2015-04-14T22:45:33.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14068" PostTypeId="2" ParentId="14066" CreationDate="2015-04-15T01:10:37.513" Score="4" Body="&lt;p&gt;You should call the Embassy of Canada in Mexico for advice on your situation. They will best be able to advise a Mexican passport holder on their entry requirements. Their number is +52 55 5724 7900.&lt;/p&gt;&#xA;" OwnerUserId="2693" LastActivityDate="2015-04-15T01:10:37.513" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14069" PostTypeId="2" ParentId="14066" CreationDate="2015-04-15T02:44:31.113" Score="4" Body="&lt;p&gt;Canada's immigration website is &lt;a href=&quot;http://www.cic.gc.ca/english/visit/visas.asp?country=Mexico&quot; rel=&quot;nofollow&quot;&gt;quite clear&lt;/a&gt;: if your passport lists your nationality as Mexican, you need a visa to enter Canada.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, a visa for one country will not affect whether or not you need a visa to visit another country; in this case, your F1 does not change the fact that you need to get a Canadian visiting visa. I have no idea whether it would affect how easily or quickly you're able to get it, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some countries, such as &lt;a href=&quot;http://canada.usembassy.gov/visas/visas/categories-and-requirements/air-or-ships-crew.html&quot; rel=&quot;nofollow&quot;&gt;the US&lt;/a&gt;, have a special visa for air crews, and private pilots might qualify in some of those countries.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-04-15T22:16:43.970" LastActivityDate="2015-04-15T22:16:43.970" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14071" PostTypeId="2" ParentId="14006" CreationDate="2015-04-15T05:12:59.640" Score="-3" Body="&lt;p&gt;The same reason why there are no winglets on gliders. The majority of propellers tips are small &amp;amp; pointy enough that there is a negligible spillover to cause wingtip vortices that makes the wing inefficient. Prop blades with wide tips like the ones in C130's  or Huey helicopter blades may be improved with winglets but such design also adds complexity(cost), weight and forces that may impede the reliability &amp;amp; safety the blades.&lt;/p&gt;&#xA;" OwnerUserId="8143" LastActivityDate="2015-04-15T05:12:59.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14072" PostTypeId="2" ParentId="8914" CreationDate="2015-04-15T05:37:37.090" Score="4" Body="&lt;p&gt;A helicopter blade must perform on a wider parameter than a propeller designed mostly for thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The straight and or flat blade was found to be good enough for the all the situations that it will encounter and was easy and cheap to produce. Specialized blades can be found but these were matched for the needs such as high speed performance, more quiet blades etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing that can be said about these special blades is that it uses more exotic materials as normal aluminum honeycombs would not withstand forces produced by such design.&lt;/p&gt;&#xA;" OwnerUserId="8143" LastEditorUserId="3386" LastEditDate="2015-04-15T15:34:19.893" LastActivityDate="2015-04-15T15:34:19.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14074" PostTypeId="1" AcceptedAnswerId="14075" CreationDate="2015-04-15T07:07:28.757" Score="20" ViewCount="20166" Body="&lt;p&gt;When I hear speaking about aviation crashes, sometimes I hear about &quot;accidents&quot; and other times about &quot;incidents&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What distinguishes them? Is there an international standard that determines how aviation crashes are classified or is it based on national regulations?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-04-15T09:03:19.163" LastActivityDate="2015-04-15T09:03:19.163" Title="What is the difference between aviation &quot;accident&quot; and &quot;incident&quot;?" Tags="&lt;accidents&gt;&lt;terminology&gt;&lt;regulations&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14075" PostTypeId="2" ParentId="14074" CreationDate="2015-04-15T07:15:13.680" Score="28" Body="&lt;p&gt;There are indeed only two 'official' classifications of aviation incidents, which are defined in &lt;a href=&quot;http://www.iprr.org/manuals/Annex13.html&quot;&gt;ICAO Annex 13&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Accident. An occurrence associated with the operation of an aircraft&#xA;  which takes place between the time any person boards the aircraft with&#xA;  the intention of flight until such time as all such persons have&#xA;  disembarked, in which:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) a person is fatally or seriously injured as a result of&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;being in the aircraft, or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;direct contact with any part of the aircraft, including parts which have become detached from the aircraft, or&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;direct exposure to jet blast,&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;except when the injuries are from natural causes, self inflicted or&#xA;  inflicted by other persons, or when the injuries are to stowaways&#xA;  hiding outside the areas normally available to the passengers and&#xA;  crew: or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) the aircraft sustains damage or structural failure which:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;adversely affects the structural strength, performance or flight characteristics of the aircraft, and&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;would normally require major repair or replacement of the affected component,&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;except for engine failure or damage. when the damage is limited to the&#xA;  engine, its cowlings or accessories: or for damage limited to&#xA;  propellers, wing tips, antennas, tires, brakes, fairings, small dents&#xA;  or puncture holes in the aircraft skin: or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c) the aircraft is missing or is completely inaccessible.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note I.-- For statistical uniformity only, an injury resulting in&#xA;  death within thirty days of the date of the accident is classified as&#xA;  a fatal injury by ICAO.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note 2.-- An aircraft is considered to be missing when the official&#xA;  search has been terminated and the wreckage has not been located.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And then there is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Incident. An occurrence, other than an accident, associated with the&#xA;  operation of an aircraft which affects or could affect the safety of&#xA;  operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They do also define 'serious incident', but simply as an incident which was nearly an accident; which is still an 'incident' by the definition above.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-04-15T07:41:31.897" LastActivityDate="2015-04-15T07:41:31.897" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14076" PostTypeId="1" AcceptedAnswerId="14077" CreationDate="2015-04-15T07:33:42.367" Score="17" ViewCount="1382" Body="&lt;p&gt;In light of the two recent incidents where aircraft landed roughly 1000 ft short of their intended runways, &lt;a href=&quot;http://avherald.com/h?article=483e7337&amp;amp;opt=1024&quot;&gt;Air Canada AC-624 at Halifax&lt;/a&gt; and &lt;a href=&quot;http://avherald.com/h?article=484c306e&amp;amp;opt=1024&quot;&gt;Asiana OZ-162 at Hiroshima&lt;/a&gt;, I started thinking the definitions used when labeling them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least in the first case, the airline labeled it a runway excursion. Given that the airplane never actually exited the runway (it touched down short and slid onto the runway), I'm a little confused, what is the definition of a runway excursion? If an aircraft never actually comes in contact with the runway, is it still a runway excursion? At what point does it simply become an off airport landing?&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2015-04-15T08:45:15.267" Title="If an airplane touches down short of the runway, and doesn't reach it, is it still a runway excursion?" Tags="&lt;accidents&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14077" PostTypeId="2" ParentId="14076" CreationDate="2015-04-15T08:29:20.053" Score="19" Body="&lt;p&gt;It depends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Skybrary says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Runway Excursion category includes also two types of occurrences which do not fit the ICAO ADREP definition for a runway excursion, however considered appropriate for inclusion due to the commonality of a number of causal and contributory factors and/or mitigation approaches:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;An aircraft attempting a landing touches down in the undershoot area of the designated landing runway within the aerodrome perimeter&lt;/strong&gt;.&lt;/li&gt;&#xA;  &lt;li&gt;A runway or taxiway other than the designated one is used for a take off or a landing.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My emphasis.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The European Commercial Aviation Safety Team (ECAST) in the European Strategic Safety Initiative (ESSI) use the Skybrary definition when writing about &lt;a href=&quot;http://easa.europa.eu/essi/ecast/main-page-2/runway-safety/&quot;&gt;Runway Excursion Prevention&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Articles within the Runway Excursion Category in SKYbrary:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Overrun on Take Off&lt;/li&gt;&#xA;  &lt;li&gt;Overrun on Landing&lt;/li&gt;&#xA;  &lt;li&gt;Directional Control&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Undershoot on Landing&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Wrong Runway&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My emphasis.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In an article &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/publication/files/101112-HS12.pdf&quot;&gt;&quot;Language and safety issues&quot;&lt;/a&gt; in Eurocontrol's magazine in 2011, Bert Ruitenberg wrote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The whole idea of putting a label such as “runway incursion” or&#xA;  “runway excursion” on a safety occurrence is to make it easier to&#xA;  file the data from the event somewhere and to compare it with&#xA;  similar occurrences. With the definitions above, a take off from a&#xA;  taxiway would be considered as a Runway Excursion when the&#xA;  Skybrary definition is used, but not with the other RE definitions&#xA;  (and rightly so, I say, better label it a “taxiway take off”). Moreover,&#xA;  in the ICAO definition, the B777 undershoot at Heathrow&#xA;  would not be a RE, but with the Skybrary definition it would be.&#xA;  Dear Safety Managers of the world, there still is a lot of work to&#xA;  be done... &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-04-15T08:45:15.267" LastActivityDate="2015-04-15T08:45:15.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14079" PostTypeId="2" ParentId="13382" CreationDate="2015-04-15T12:46:03.963" Score="20" Body="&lt;p&gt;The lift augmentation has nothing to do with Magnus lift (or the Coanda effect).  It is simply an increase in the dynamic pressure across the entire streamtube of the wing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the low takeoff and landing speeds (slightly above a 61 knot stall speed), the induced velocity of the propeller almost doubles the velocity that the wing sees; and the lift is a function of the effective velocity squared.  But due to swirl and other effects the wing doesn't experience a 4x increase in lift, but about 2 to 3 times.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The objective of the inboard propellers is not to achieve a high propulsive efficiency, instead we want those inboard props to achieve high induced velocities - think of them as part of the high lift system (which happens to also provide thrust redundancy).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact landing is the critical case, and having lower propulsive efficiency (and a poorer spanwise lift distribution because of the swirl effects) is helpful in creating sufficient drag.  The inboard props are not active in cruise flight, but simply fold against the nacelle (many motorgliders already do this type of folding on the nose).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By only using the wingtip propeller at cruise, we're able to achieve a ~95% propulsive efficiency (versus 75 to 85% with a typical fuselage nose propeller installation).  The reason for this is because we have lower blockage and scrubbing drag, as well as being able to take advantage of the strong wingtip vortex by rotating against it.  Since electric motors don't experience a power lapse with altitude (because it's non airbreathing) we have far too much power at altitude anyway so by only using the wingtip motor it doesn't cause much penalty in motor weight (and electric motors achieve ~6x lower weight per horsepower than a reciprocating engine).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of batteries and range, the key is to achieve high efficiency cruise flight and it looks like with current batteries a 200 mile range is achievable.  By adding a small &amp;lt;50 hp range extender motor, the aircraft will be able to achieve ~400 mile range.  We're currently designing an X-plane that will fly in 2017 to substantiate all these numbers, with the ground test rig (wing and truck) providing an aerodynamic database to validate our analysis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that I'm the NASA Principal Investigator of the LEAPTech Distributed Electric Propulsion integration approach, and the Convergent Electric Propulsion Technology (CEPT) X-Plane demonstrator.  We have a team across NASA Langley and Armstrong, as well as two great small companies, Joby Aviation and ESAero who are retrofitting a Tecnam P2006T with a Distributed Electric Propulsion wing system.  &lt;/p&gt;&#xA;" OwnerUserId="8146" LastEditorUserId="2407" LastEditDate="2015-04-15T14:39:45.480" LastActivityDate="2015-04-15T14:39:45.480" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14081" PostTypeId="1" CreationDate="2015-04-15T16:31:14.943" Score="10" ViewCount="1040" Body="&lt;p&gt;I know this question is somewhat general and could vary from plane to plane so I will elaborate on the plane in question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific plane I am curious about is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mooney_M-18_Mite&quot; rel=&quot;nofollow&quot;&gt;Mooney Mite&lt;/a&gt; which has a metal center section but wooden wings and wooden rear half and empennage which at the age most of these planes are is prone to issues. It seems like a great little plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is can one be built out of aluminum to the same specs (maybe with a bigger engine) and still fly properly or will the weight change (CG change) affect the plane too drastically?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise could a Piper Cub or similar be made of all metal (again with a bit more power up front) and still be an effective plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the record I do not currently have plans to build this plane (although it was available as a kit plane at some point in history. I am aware of the certification issues with making alterations like to an existing plane. I was asking more about if it was possible from an aeronautical standpoint.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="6919" LastEditDate="2015-05-19T00:27:42.757" LastActivityDate="2019-08-10T02:57:18.283" Title="Can a wooden/fabric cover design be built of metal?" Tags="&lt;aircraft-design&gt;&lt;aerospace-materials&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14083" PostTypeId="2" ParentId="14038" CreationDate="2015-04-15T17:43:48.857" Score="-1" Body="&lt;p&gt;I'd say, sorry, can't retrieve the reference now, that: 'detonation', is not the same as: 'knocking', even if you consider: 'knocking', as the audible expression of a detonation, or preignition or other forms of undesirable combustion inside an Internal Combustion Piston Engine, be the piston alternative or a rotating rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Toyota tested successfully, 7% fuel economy improvement, a cleaner exhaust, in a Wankel Rotary Engine, substituting a glow-plug in the leading site for the ordinary spark plug. Another concept cited here is the presence of two plugs in aviation engines, my idea was that the purpose of a double plug and double ignition system, e.g. two magnetos, is just a redundancy for safety reasons, having a replacement ignition system in the case of failure of one, but the rate and pace of combustion, or flame front speed inside the working chamber of an ICE is also influenced by having one or more plugs, by the presence of hot spots, swirl or quenching inside the combustion chamber, and by the shape of combustion chamber and valve mechanism, if there's any, but the issue is complex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The books by Harry Ricardo: 'The high-speed internal combustion engine', a classic of ICEs, deal with this and other combustion issues.                  *link to download the 1931 edition: &lt;a href=&quot;http://www.mediafire.com/download/gn1o0vyvzaz/The+High+Speed+Internal+Combustion+Engine+Ricardo+1931.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.mediafire.com/download/gn1o0vyvzaz/The+High+Speed+Internal+Combustion+Engine+Ricardo+1931.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also available was: 'Aircraft Propulsion', by C. Fayette Taylor, Smithsonian Annals of Flight, 1971.&#xA;Hope it's useful for you. Regards. Salut †&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-04-15T18:19:23.130" LastActivityDate="2015-04-15T18:19:23.130" CommentCount="3" CommunityOwnedDate="2015-04-15T17:43:48.857" ContentLicense="CC BY-SA 3.0" />
  <row Id="14084" PostTypeId="2" ParentId="14081" CreationDate="2015-04-15T17:57:28.567" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ed_Swearingen&quot; rel=&quot;nofollow&quot;&gt;Ed Swearingen&lt;/a&gt; used to say that it made little difference if you build an airplane from wood, aluminum or carbon epoxy - in the end the weight would not be too different if the parts are designed well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that many aircraft in the 1930s used the combination of an aluminum frame and fabric covering. Especially the control surfaces of many aircraft, but also the fuselage, wing and tail surfaces of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Vickers_Wellington&quot; rel=&quot;nofollow&quot;&gt;Vickers Wellington&lt;/a&gt; were built this way. Also, many gliders before the advent of fiber-composite structures used a welded steel-tube frame covered with fabric for their fuselage. Since glueing works better with wood, the fabric cover needs to be sewed to the ribs and stringers, so suction forces will not lift it up over an extensive area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Key is the limited dynamic pressure: If you do not increase operating speeds, exchanging wood for aluminum will be straightforward. Only the torsion box of the wing would need closer attention, since the low weight per area of plywood cannot be recreated with aluminum sheet - the wall thickness and the resulting buckling strength would be too low. You would be well advised to add more stiffeners and ribs!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-04-15T17:57:28.567" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14085" PostTypeId="2" ParentId="14006" CreationDate="2015-04-15T18:04:41.060" Score="1" Body="&lt;p&gt;The concept of 'winglets' was applied in early days of aviation by the inventions of Henri Coanda, patents: 1937GB191112740, 1910; CA370885, 1937; and to boat propellers; you can have a look, also in ESPACENET, at patents: ES-0444150, Inventor: 'Gonzalo Perez Gomez', and ES-8300608, 1987, same; and ES-0293837_U by 'Ramon Ruiz Fornella', all from: 'Astilleros espanoles'.&#xA;'NASA Technical Memorandum 87771', by Milton A. Beheim: 'NASA Research in Aircraft Propulsion', shows a propeller with 'winglets'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd say that one of the reasons for winglets in wing tips is to reduce the marginal vortex, due to the compensation of the difference in pressures between the upper and lower surface of wing, this 'vortex' or 'swirl' increases drag, and thus impairs overall airplane efficiency.&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-04-15T18:18:13.627" LastActivityDate="2015-04-15T18:18:13.627" CommentCount="1" CommunityOwnedDate="2015-04-15T18:04:41.060" ContentLicense="CC BY-SA 3.0" />
  <row Id="14086" PostTypeId="2" ParentId="686" CreationDate="2015-04-15T20:30:18.283" Score="6" Body="&lt;h2&gt;Advantages of forward CG position:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Higher stability, so less attention is needed to keep the trimmed aircraft straight and level.&lt;/li&gt;&#xA;&lt;li&gt;If the aircraft can be made to spin, the spin is easier to end.&lt;/li&gt;&#xA;&lt;li&gt;For taildraggers: The tail can be lifted up earlier during the take-off run.&lt;/li&gt;&#xA;&lt;li&gt;For tricycle landing gear aircraft: Better stability on the ground.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Well, that's about it!&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Advantages of rear CG position:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less trim drag, because less downforce needs to be created at the tail and compensated by the wing.&lt;/li&gt;&#xA;&lt;li&gt;Better maneuverability and lower control forces, because less control surface deflection is needed for the same excursion from the trimmed state.&lt;/li&gt;&#xA;&lt;li&gt;Lower minimum speed, which translates into lower take-off and landing distances.&lt;/li&gt;&#xA;&lt;li&gt;For taildraggers: More stability on the ground against tipping over.&lt;/li&gt;&#xA;&lt;li&gt;For tricycle landing gear aircraft: Lower rotation speed possible at takeoff.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that shifting the CG more aft, behind the neutral position, will make the aircraft statically unstable and will increase trim drag again, because now the tail will operate at abnormally high lift coefficients which come with high induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical application for forward CG positions is a manually controlled long range aircraft which will fly in gusty weather. Then it will be beneficial to have high stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical applications for rear CG positions are performance- or maneuverability-optimized aircraft like gliders or aerobatic airplanes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-15T20:37:08.350" LastActivityDate="2015-04-15T20:37:08.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14087" PostTypeId="2" ParentId="14033" CreationDate="2015-04-15T21:42:37.943" Score="7" Body="&lt;p&gt;I've downvoted the answer from Habu because it ignores a major difference in engine design.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small GA planes, the Lycoming engines have the carburetor bolted to the bottom of the crankcase where it gets some heat from the hot oil.  Fuel/air exits the top of the carb where it is routed through pipes inside the crankcase where the hot oil further increases its temperature. This makes the Lyc generally resistant to induction icing.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Continentals, the updraft carburetor is not mounted on the hot crankcase but on part of the manifold assembly, insulating the carb itself from the heat of the crankcase, and the fuel/air mixture is routed directly to the intake manifold and not through the engine crankcase which holds the hot oil.  The result is that the TCM O-300 engine has earned the reputation of being an icemaker. The difference in the POH instructions as to how to fly each engine is directly attributable to engine design and it has absolutely nothing to do with the weather in Vero Beach versus Wichita.     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm going to post line drawing images of the two engines to illustrate the point. First: Lycoming.  Second: Continental &lt;img src=&quot;https://i.stack.imgur.com/CDZQa.jpg&quot; alt=&quot;Lycoming 0-360&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yLosO.jpg&quot; alt=&quot;Continental 0-200&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the original poster is missing is that for most of its history, the Cessna design used Continental engines.  Now that it has switched to Lycoming engines, the difference in the engines is probably zero, but they have not abandoned the former POH instructions as that might be confusing to the pilots that fly these planes.  After all, using carb heat more often as a default procedure for the Lyc powered Cessnas is a safe procedure.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-04-15T22:12:49.023" LastActivityDate="2015-04-15T22:12:49.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14088" PostTypeId="1" AcceptedAnswerId="14089" CreationDate="2015-04-15T23:03:10.417" Score="18" ViewCount="21534" Body="&lt;p&gt;If a pilot uses a notch of flaps on takeoff, when do they get retracted? At that time, what changes (i.e. climb rate, speed, pitch)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;NOTE: I have purposefully not specified the type of airplane.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="65" LastEditDate="2015-04-20T13:11:48.370" LastActivityDate="2019-01-21T20:23:24.423" Title="If flaps are used on takeoff, when should they be retracted?" Tags="&lt;takeoff&gt;&lt;flaps&gt;" AnswerCount="8" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14089" PostTypeId="2" ParentId="14088" CreationDate="2015-04-16T01:00:17.160" Score="28" Body="&lt;p&gt;The short answer is, it depends. The FAA Airplane Flying Handbook merely states that this &lt;em&gt;can&lt;/em&gt; be performed once the aircraft has established positive climb, but does not specify exactly when.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately two situations arise:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The airplane is sufficiently large/high performance that normal operating procedures specify the use of flaps for all takeoff scenarios, in which case the manufacturer or the operator (if applicable) may well specify a flap retraction schedule, which seeks to allow the aircraft to accelerate effectively during climb out, avoid overstressing the flaps by having the aircraft fly past the maximum speed for each flap setting, while at the same time maintain a comfortable margin above stall speed.&lt;/li&gt;&#xA;&lt;li&gt;The airplane only requires flaps for certain kinds of takeoffs such as maximum performance or soft-field efforts. In that case, procedures may be somewhat looser in defining the exact moment of flap retraction. A climb checklist, should you choose to use one, will likely mention the flap configuration as an action/verification item, so that would likely be a good moment to retract them if you haven't done so already. Personally , I usually retract them passing through 200-300 feet AGL, which usually coincides to the aircraft being at least half-way between clean configuration Vx and Vy (I've been mostly flying Skyhawks, Skylanes, Arrows, and Huskies). Whichever way you do it though, you want to avoid retracting them too low and too slow, but also forgetting about them and blowing through Vfe (which even light, slow airplanes can do quite handily).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With respect to the actual changes in aircraft behavior, you'll likely notice the following things:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A slight-nose down moment as wing's characteristics change, which influences the airflow reaching your horizontal stabilizer. The converse applies when extending flaps. Mind you, this is an airplane model-specific thing and one that seemed most noticeable to me in the Cessna family of light singles. &lt;/li&gt;&#xA;&lt;li&gt;For the same power setting and pitch attitude, the aircraft will begin to accelerate quicker for each notch of flap retraction.&lt;/li&gt;&#xA;&lt;li&gt;Climb rate is trickier as it is dependent on your power setting, airspeed, and pitch angle; your inputs will matter. However, generally speaking, the reduction in drag would lead to a greater difference between power available (or power set) and power required, so, all things being equal, you would likely see an increase in climb rate.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="28837" LastEditDate="2019-01-21T20:23:24.423" LastActivityDate="2019-01-21T20:23:24.423" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="14090" PostTypeId="2" ParentId="14088" CreationDate="2015-04-16T01:03:55.920" Score="8" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_08/pdfs/AERO_Q408_article05.pdf&quot; rel=&quot;nofollow&quot;&gt;a Boeing publication&lt;/a&gt; flaps are usually fully retracted at an altitude of about 3,000 ft.  As you probably know flaps increase lift and drag.  So as the plane increases speed (and thereby lift potential), the need for flaps decreases.  I imagine by the time a plane reaches 3,000 feet is has attained enough air speed to no longer need flaps.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastEditorUserId="1961" LastEditDate="2015-04-16T19:19:31.400" LastActivityDate="2015-04-16T19:19:31.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14091" PostTypeId="1" AcceptedAnswerId="14274" CreationDate="2015-04-16T03:06:43.107" Score="8" ViewCount="861" Body="&lt;p&gt;It's possible (and, at least by AOPA, encouraged) to submit flight plans for VFR flights, but ATC still do not perform many of the services they provide for IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose I submit a flight plan for a Piper Cub under which I take off, climb to FL10,000, and dock with the International Space Station before landing on the White House front lawn? Or, slightly less egregiously, a plan under which I clip an &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Air_Defense_Identification_Zone_(North_America)&quot;&gt;ADIZ&lt;/a&gt; but I don't mark it as DVFR?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will the flight plan be rejected when I try to submit it? Will Flight Services refuse to open it? Will they open it anyways and just let me do my thing?  Are they &lt;em&gt;required&lt;/em&gt; to verify it in some way?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-04-16T03:19:39.117" LastActivityDate="2018-02-01T21:57:53.493" Title="Does the FAA verify or authorize VFR flight plans?" Tags="&lt;faa&gt;&lt;faa-approval&gt;&lt;flight-plans&gt;&lt;fss&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14092" PostTypeId="2" ParentId="14088" CreationDate="2015-04-16T03:12:47.193" Score="17" Body="&lt;p&gt;Below is sample screen of a Boeing 777's Primary Flight Display. See those flaps marks on the speed tape?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fsJmX.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the thing: you &lt;em&gt;don't&lt;/em&gt; want to retract the flaps from 5 to 1 when you're slower than the stall speed at flaps 1. So in terms of flaps retraction schedule, you'll:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Accelerate to (at least) the minimum speed for flaps 5 in the takeoff roll.&lt;/li&gt;&#xA;&lt;li&gt;Pitch up really high (e.g. 12.5 degrees)&lt;/li&gt;&#xA;&lt;li&gt;Upon reaching &lt;em&gt;acceleration altitude&lt;/em&gt; (a.k.a. &lt;em&gt;flap retraction altitude&lt;/em&gt;), pitch down a bit (e.g. from 12.5 to 10 degrees) and let the aircraft accelerate.&lt;/li&gt;&#xA;&lt;li&gt;When the speed passes the &quot;1&quot; mark on the speed tape, set flaps 1.&lt;/li&gt;&#xA;&lt;li&gt;When the speed passes &quot;up&quot; on the speed tape, fully retract the flaps.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Acceleration altitude is usually 1,000 feet or 1,250 feet. So that &lt;em&gt;really steep climb&lt;/em&gt; right after takeoff roll lasts only about 30 seconds.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you're flying a small aircraft, chances are you'll only use flap in a short field takeoff. The general procedure would be similar:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;During takeoff roll, pitch up to V&lt;sub&gt;x&lt;/sub&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Once clear of obstacles, adjust pitch to maintain V&lt;sub&gt;y&lt;/sub&gt;.&lt;/li&gt;&#xA;&lt;li&gt;As you adjust pitch from V&lt;sub&gt;x&lt;/sub&gt; to V&lt;sub&gt;y&lt;/sub&gt;, the aircraft accelerates. When you're confident that you're above the stall speed in clean configuration (or when you pass a manufacturer specified speed), retract the flaps.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-04-16T03:12:47.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14093" PostTypeId="1" CreationDate="2015-04-16T03:20:31.650" Score="4" ViewCount="546" Body="&lt;p&gt;How do civilian fighter jet operations arrange airspace usage for conducting flight tours? Do they use military operation areas? If they fly into class A can they perform maneuvers, or do they need to stay below class A? One such operation is &lt;a href=&quot;http://www.migflug.com/en/jet-fighter-flights.html&quot; rel=&quot;nofollow&quot;&gt;migflug&lt;/a&gt;.&#xA;When flying in airliners cross country I look out the window and think what it would be like to experience flying around and between cumulonimbus clouds in a jet fighter, but doubt ATC would allow it. It got me to wondering how the civilian jet tours handle airspace and speed restrictions.&lt;/p&gt;&#xA;" OwnerUserId="3670" LastActivityDate="2015-04-16T07:46:46.673" Title="What special airspace exemptions are granted for civilian fighter jets?" Tags="&lt;military&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14094" PostTypeId="1" AcceptedAnswerId="14187" CreationDate="2015-04-16T04:09:22.853" Score="7" ViewCount="2190" Body="&lt;p&gt;It's that time again, gotta re-up my CFI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I always forget when I'm filling out IACRA whether CFI renewals (in the United States) based on student pass rate percentage are considered &quot;activites&quot; or &quot;duties and responsibilities&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Which of the two, &quot;duties and responsibilites&quot; or &quot;activities&quot; is the appropriate choice when submitting an IACRA application for a CFI renewal based on pass rate?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="572" LastEditDate="2015-04-16T05:54:36.103" LastActivityDate="2015-04-17T17:39:27.237" Title="Which refers to CFI renewal based on pass rate, &quot;activities&quot; or &quot;duties and responsibilities&quot;?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14095" PostTypeId="1" AcceptedAnswerId="14097" CreationDate="2015-04-16T06:41:22.083" Score="11" ViewCount="2590" Body="&lt;p&gt;I had this discussion with my dad about a question he had asked. Basically he said:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a plane flies faster than the speed of sound, will he be able to overtake his own sound and hear itself?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(let's leave behind the fact that he can run out of fuel or that the sound finishes before he hears it)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I disagreed because it seemed illogical to me, but we never actually found hard evidence to determine if the statement is true or false.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can a plane actually do this?&lt;/p&gt;&#xA;" OwnerUserId="6912" LastEditorUserId="100" LastEditDate="2015-04-16T08:56:24.263" LastActivityDate="2020-02-03T17:17:09.653" Title="When a plane flies faster than the speed of sound, does the distance between plane and sound increase?" Tags="&lt;airspeed&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14097" PostTypeId="2" ParentId="14095" CreationDate="2015-04-16T07:01:49.693" Score="17" Body="&lt;p&gt;I think you are missing some physics knowledge, so let's start from here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If a plane flies faster than the speed of sound&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Sound#Physics_of_sound&quot; rel=&quot;noreferrer&quot;&gt;Sound&lt;/a&gt; is a compression wave that travels through air. Given a certain air temperature, the sound will travel at &lt;a href=&quot;http://en.wikipedia.org/wiki/Speed_of_sound#Practical_formula_for_dry_air&quot; rel=&quot;noreferrer&quot;&gt;different speeds&lt;/a&gt; through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane flies faster than the speed of sound means that the compression waves it is generating will remain behind the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9QJ3z.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;image from &lt;a href=&quot;http://www.physicscentral.com/buzz/blog/index.cfm?postid=103798762154496933&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;will he be able to overtake his own sound and hear itself?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see on the right picture, if the aircraft is travelling faster that the speed of sound, the compression waves it generated in the past will remain behind. If it would stop/slow down, the waves would then catch up with the plane and a person on board would be theoretically capable of hearing them.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2017-01-23T09:40:36.920" LastActivityDate="2017-01-23T09:40:36.920" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14098" PostTypeId="2" ParentId="14093" CreationDate="2015-04-16T07:46:46.673" Score="7" Body="&lt;p&gt;The same regulations apply to civilian ex-military aircraft as they apply to any other aircraft. Whether flying IFR or VFR, you will need to comply with the same rules, e.g. speed restrictions, airspace restrictions when under VFR, meteorological conditions, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An exception can be speed restrictions, where a speed restriction would be in contradiction with the parameters of the aircraft to perform safe flight, e.g. the minimum clean speed being above 250kts or similar.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-04-16T07:46:46.673" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14099" PostTypeId="1" AcceptedAnswerId="14100" CreationDate="2015-04-16T08:13:39.413" Score="12" ViewCount="10265" Body="&lt;p&gt;I'm wondering how bad it is to fly a short distance, such as ~50km, with a big airplane. How much less fuel does it take to fly at high altitudes compared to low? And how much of the fuel is spent on start/landing? Flying between continents is never a problem, but if a politician flies a shorter distance all hell breaks loose.&lt;/p&gt;&#xA;" OwnerUserId="8159" LastActivityDate="2015-04-16T20:03:09.343" Title="How much fuel does it take to start/land an aircraft, compared to normal flight?" Tags="&lt;fuel&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14100" PostTypeId="2" ParentId="14099" CreationDate="2015-04-16T10:54:13.000" Score="9" Body="&lt;p&gt;The fuel consumption or fuel burn rate is dependent on the aircraft type, size, engine configuration, cruise altitude, temperature, thrust setting and other factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general: The larger the aircraft, the less economic do short flights become due to weight/size and fuel burn on takeoff/climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some values I found for the CRJ2, the source may not be entire citable:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Approximate total burn pounds / hour&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Taxi: 700 (Both engines and APU)&lt;br&gt;&#xA;  &lt;strong&gt;Takeoff: 6000-7000&lt;/strong&gt; (depending on temperature, elevation, reduced/full thrust, etc)&lt;br&gt;&#xA;  &lt;strong&gt;Climb: 6000-3500&lt;/strong&gt; (reducing as as altitude increases)&lt;br&gt;&#xA;  &lt;strong&gt;Cruise: 2500-3000&lt;/strong&gt; (depending on altitude/weight/etc... subtract 500 for long range, add 500 for high speed)&lt;br&gt;&#xA;  Holding: 1800-2400 (depending on altitude/speed)&lt;br&gt;&#xA;  Normal descent: 1500&lt;br&gt;&#xA;  Idle descent: 600&lt;br&gt;&#xA;  Approach: 2000 (fully configured)  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/223243/&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.airliners.net&lt;/a&gt; - Author: Flyf15)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also read the following related questions to understand how altitude affects fuel efficiency:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/1609/572&quot;&gt;Why do jet engines get better fuel efficiency at high altitudes?&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/931/572&quot;&gt;How does flight duration affect the hourly fuel consumption in heavy aircraft?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-04-16T10:54:13.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14101" PostTypeId="2" ParentId="14091" CreationDate="2015-04-16T13:54:56.460" Score="5" Body="&lt;p&gt;No verification is done.  You may file what you will.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This places all the responsibility for airspace incursions on the pilot in command (&quot;PIC&quot;) where it belongs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only real effect of the VFR flight plan is to engage the Search and Rescue folks if you don't close the flight plan on time, and give them the route you intended to fly when you filed so that they know basically where to start the search.  Note, the first thing the SAR folks will do is call your intended destination to see if you have arrived.  If no, then the search begins in earnest.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-04-16T13:54:56.460" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14102" PostTypeId="1" AcceptedAnswerId="14962" CreationDate="2015-04-16T15:17:49.767" Score="19" ViewCount="1946" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/utBky.jpg&quot; alt=&quot;mystery biplane&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried a number of searches with absolutely no luck. I remember a few that looked sort of similar without that smooth aerodynamic nose and body. I did try at least.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this helps, the individual standing before the plane is believed to be of French origin or descent.&lt;/p&gt;&#xA;" OwnerUserId="8160" LastEditorUserId="1858" LastEditDate="2019-11-23T23:03:39.223" LastActivityDate="2019-11-23T23:03:39.223" Title="Can anyone identify this 1910s era biplane?" Tags="&lt;aviation-history&gt;&lt;aircraft-identification&gt;&lt;biplane&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="14103" PostTypeId="2" ParentId="14088" CreationDate="2015-04-16T15:47:42.017" Score="5" Body="&lt;p&gt;First and foremost, in light planes flaps should be retracted above V&lt;sub&gt;S&lt;/sub&gt; and below V&lt;sub&gt;FE&lt;/sub&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a C172, you have:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;V&lt;sub&gt;S&lt;/sub&gt; 47kts Stall Speed in Clean Configuration. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;V&lt;sub&gt;FE&lt;/sub&gt; 139kts 10 Degrees Flap Extended, 85kts 20-30 Degrees Flap Extended.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's a pretty wide range, so it would be hard to get it wrong, and as a matter of safety, you would probably want to use the approach multiplier of 1.3 as the minimum, which is 61. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So next question is, what is the effect of raising the flaps in a climb? Most importantly, raising the flaps decreases the angle of attack, which decreases induced drag, so raising the flaps earlier is better, so somewhere in the range of 61-71 for the Cessna.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;[It has been suggested that &quot;positive rate&quot; should be used for flaps, but I disagree. Unlike gear, which is all drag, 10% flaps are mostly lift, with very little added induced drag. Higher flaps settings for short= and soft-field takeoffs have a different set of considerations.]&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="65" LastEditDate="2015-04-20T13:14:44.110" LastActivityDate="2015-04-20T13:14:44.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14104" PostTypeId="2" ParentId="14088" CreationDate="2015-04-16T15:50:06.333" Score="0" Body="&lt;p&gt;The lift flaps generate is directly proportional to speed but the drag they introduce is proportional to speed squared. Double the speed, double the lift, quadruple the drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft accelerates after take-off, the extra lift generated by having the flaps extended will be countered by the extra drag generated by the increased speed so they are retracted in stages to maintain that balance. &lt;/p&gt;&#xA;" OwnerUserId="2233" LastActivityDate="2015-04-16T15:50:06.333" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14106" PostTypeId="2" ParentId="381" CreationDate="2015-04-16T18:03:38.297" Score="6" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Bf_110&quot; rel=&quot;nofollow noreferrer&quot;&gt;Messerschmitt Bf-110&lt;/a&gt; used a conformal fuel tank under the forward fuselage, colloquially known as &quot;Dackelbauch&quot; (Dachshund belly). The picture below should explain well why this name was chosen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SKfCr.jpg&quot; alt=&quot;Bf-110 with conformal tank under the forward fuselage&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They were introduced to allow planes stationed in Norway to attack targets in Northern England. When empty, their content would be a dangerous mixture of air and fuel vapor, so they were not very popular with their crews and only used briefly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want, you could even call the center wing tank of some biplanes a conformal tank. However, conformal tanks are rather unusual.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T08:46:04.013" LastActivityDate="2015-05-10T08:46:04.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14107" PostTypeId="2" ParentId="14099" CreationDate="2015-04-16T19:57:05.533" Score="4" Body="&lt;p&gt;The uproar was justified. The Swedish politicians should have driven to one airport and flown from there in one leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two effects which make short flights inefficient:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The relative length of unproductive taxiing and initial acceleration becomes bigger the shorter the flight is, and&lt;/li&gt;&#xA;&lt;li&gt;Flying at low altitude is slower, so much more fuel is consumed per distance flown.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You also need to burn more fuel for climbing, but you will get that back on descent when the aircraft can reduce thrust, just like you can coast downhill in a car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet aircraft reach their highest efficiency when flown near the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tropopause&quot; rel=&quot;nofollow noreferrer&quot;&gt;tropopause&lt;/a&gt;. Here, air density is only a quarter of what it is at the ground, and the aircraft will fly twice as fast up there when flying at its optimum lift to drag ratio. In addition, the colder air at altitude will make jet engines &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983#4983&quot;&gt;more efficient&lt;/a&gt;. Therefore, flying those 41 km used more than twice as much fuel per km traveled than flying from Sweden to New York. Add to this that the aircraft needed to taxi for several km twice instead of only once, and also needed to spend the fuel for the take-off run twice. While the potential energy added during climb can be regained during descent, the initial acceleration energy is mostly wasted as brake heat, spoiler turbulence and reverse thrust. This adds up to several 100 kgs of fuel for a large airliner.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-04-16T20:03:09.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14108" PostTypeId="1" CreationDate="2015-04-16T20:03:11.563" Score="4" ViewCount="1959" Body="&lt;p&gt;I'm looking to get a bit of info on Chemical Oxygen generation, especially as done on aircraft. I understand the process of Chemical Oxygen Generation. I'm also aware that weight for weight it produces far more oxygen than Oxygen gas canisters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I want to know is are there any other advantages? Does it have added safety benefits when compared to high pressure gaseous oxygen storage? The Oxygen candle burns extremely hot when it goes off but I'd imagine high pressure gas canisters could be far more dangerous and prone to exploding if damaged?&lt;/p&gt;&#xA;" OwnerUserId="8163" LastEditorUserId="1467" LastEditDate="2015-04-19T12:25:19.530" LastActivityDate="2019-06-25T13:15:47.313" Title="What are the advantages of Chemical Oxygen Generation over Gaseous Canisters on board of aircrafts?" Tags="&lt;safety&gt;&lt;oxygen&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14109" PostTypeId="1" CreationDate="2015-04-16T20:37:47.030" Score="11" ViewCount="1632" Body="&lt;p&gt;When planes crash at airports, it seems the only video available is amateur footage several miles away with terrible quality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why don't we have video recordings of all takeoffs and landings at the airport?&lt;/p&gt;&#xA;" OwnerUserId="8164" LastEditorUserId="4215" LastEditDate="2015-04-17T06:30:57.193" LastActivityDate="2016-07-02T05:57:28.837" Title="Why don't we have video recording of runways takeoffs/landings?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="14110" PostTypeId="1" CreationDate="2015-04-16T21:07:41.580" Score="6" ViewCount="22860" Body="&lt;p&gt;I am always confused about how to calculate safety altitude, especially when it comes to even heights and odd heights, e.g. is &lt;code&gt;7500ft&lt;/code&gt; even or odd?&lt;/p&gt;&#xA;" OwnerUserId="8165" LastEditorUserId="572" LastEditDate="2015-04-17T05:43:05.373" LastActivityDate="2020-02-03T17:05:56.593" Title="How do I determine odd or even when working with altitudes?" Tags="&lt;safety&gt;&lt;visual-flight-rules&gt;&lt;altitude&gt;" AnswerCount="7" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14111" PostTypeId="1" CreationDate="2015-04-16T21:14:32.787" Score="2" ViewCount="3327" Body="&lt;p&gt;Please describe and define the following terms:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Homing&lt;/li&gt;&#xA;&lt;li&gt;0 degree relative bearing&lt;/li&gt;&#xA;&lt;li&gt;Tracking&lt;/li&gt;&#xA;&lt;li&gt;Hold&lt;/li&gt;&#xA;&lt;li&gt;Entry&lt;/li&gt;&#xA;&lt;li&gt;Holding pattern&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are its uses and purposes?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Any one to suggest a thorough instrument book as well.&lt;/p&gt;&#xA;" OwnerUserId="8165" LastEditorUserId="1696" LastEditDate="2015-04-16T21:36:00.867" LastActivityDate="2015-04-17T06:10:00.040" Title="What are the meanings of these terms related to instrument flight?" Tags="&lt;instrument-flight-rules&gt;&lt;terminology&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14112" PostTypeId="2" ParentId="14110" CreationDate="2015-04-16T21:56:17.407" Score="9" Body="&lt;p&gt;Look at the thousands of feet only.&lt;br&gt;&#xA;Is &lt;code&gt;7&lt;/code&gt;(thousand) even or odd?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure a mathematician views 7,500 as equally close to 8,000 as 7,000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in aviation terms, it is &lt;strong&gt;&lt;em&gt;7,000 plus another 500 feet&lt;/em&gt;&lt;/strong&gt;, and therefore an odd altitude.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-04-17T13:37:01.860" LastActivityDate="2015-04-17T13:37:01.860" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14113" PostTypeId="2" ParentId="14110" CreationDate="2015-04-16T22:01:48.033" Score="9" Body="&lt;p&gt;See below for the wording of 14CFR91.159 which is the reg you need to answer this question.  Note it says &amp;quot;Odd [or Even] thousand feet plus 500&amp;quot;.  7000 is an odd thousand even though it is an even number.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§ 91.159 - VFR cruising altitude or flight level.&lt;/p&gt;&#xA;&lt;p&gt;Except while holding in a holding pattern of 2 minutes or less, or while turning, each person operating an aircraft under VFR in level cruising flight more than 3,000 feet above the surface shall maintain the appropriate altitude or flight level prescribed below, unless otherwise authorized by &amp;gt;ATC:&lt;/p&gt;&#xA;&lt;p&gt;(a) When operating below 18,000 feet MSL and—&lt;/p&gt;&#xA;&lt;p&gt;(1) On a magnetic course of zero degrees through 179 degrees, any odd thousand foot MSL altitude 500 feet (such as 3,500, 5,500, or 7,500); or&lt;/p&gt;&#xA;&lt;p&gt;(2) On a magnetic course of 180 degrees through 359 degrees, any even thousand foot MSL altitude 500 feet (such as 4,500, 6,500, or 8,500).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="291" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-16T22:19:34.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14114" PostTypeId="1" CreationDate="2015-04-16T22:30:48.077" Score="5" ViewCount="343" Body="&lt;p&gt;I don't get to fly as often as I'd like. I know that simulators are good for brushing up on technique, learning new systems, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there techniques that pros use (commercial or military) to stay sharp about things when they aren't able to actually fly? Specifically things that I would do not in a simulator, but say I have a couple months where I can't fly, but have an hour commute, or 30 minutes per day that I could do something flying-related to stay sharp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize there is no substitute for actual flying, but I always feel a little rusty (mostly I just feel a little behind the airplane) when I haven't flown for a month or two. Are there things that other pilots do that I could learn to do in my down time that would mitigate this?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="65" LastEditDate="2015-04-20T14:01:39.017" LastActivityDate="2015-04-29T22:18:21.133" Title="What techniques professional pilots use to keep their piloting skills sharp when not flying for an extended period?" Tags="&lt;pilot-technique&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14115" PostTypeId="1" AcceptedAnswerId="14117" CreationDate="2015-04-16T22:45:51.093" Score="14" ViewCount="2624" Body="&lt;p&gt;On the &lt;a href=&quot;https://www.faa.gov/uas/model_aircraft/&quot;&gt;FAA website&lt;/a&gt; the FAA says that you should not fly your model aircraft out of line of sight. Does this mean you cannot use &lt;a href=&quot;https://en.wikipedia.org/wiki/First-person_view_%28radio_control%29&quot;&gt;FPV&lt;/a&gt; goggles?&lt;/p&gt;&#xA;" OwnerUserId="8113" LastEditorUserId="1696" LastEditDate="2015-04-17T02:08:38.470" LastActivityDate="2016-01-30T22:34:42.940" Title="Has the FAA banned FPV for model aviation?" Tags="&lt;faa-regulations&gt;&lt;model-aircraft&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14116" PostTypeId="2" ParentId="14114" CreationDate="2015-04-17T00:41:13.843" Score="2" Body="&lt;p&gt;I am not a professional but I'll offer up a few things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to read here. Its actually quite a good place to learn things and see questions you might not otherwise ask yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read the FAR/AIM (or at least the most recent updates). This may seem boring but its a good way to stay current on new rules and regulations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly the simulator. I like to fly the sim mainly for fun, but some times it's good just to remember what the instruments are shown when a variety of things happen. X-Plane now offers the ability to capture and use live weather. Plan a flight, then get in the sim with current conditions and see how good your wind calculations are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read your POH (if you own a plane or fly the same one frequently). Do you remember all your emergency checklists? All your operating procedures? Everything to check for preflight? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would always buy a road atlas, get in your car, get yourself lost and try and find your way home using only paper maps and a compass. Might be a good navigation exercise.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-04-20T13:58:49.240" LastActivityDate="2015-04-20T13:58:49.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14117" PostTypeId="2" ParentId="14115" CreationDate="2015-04-17T01:59:32.307" Score="12" Body="&lt;p&gt;The FAA has &lt;a href=&quot;https://www.faa.gov/uas/media/model_aircraft_spec_rule.pdf&quot;&gt;interpreted the rules&lt;/a&gt; to mean that the operator must have a line-of-sight view of the model aircraft at all times, and that &lt;strong&gt;FPV does not qualify&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Based on the plain language of the statute, the FAA interprets this&#xA;  requirement to mean that: (1) the aircraft must be &lt;strong&gt;visible at all&#xA;  times to the operator&lt;/strong&gt;; (2) that the operator must use his or her own&#xA;  &lt;strong&gt;natural vision&lt;/strong&gt; (which includes vision corrected by standard eyeglasses&#xA;  or contact lenses) to observe the aircraft; and (3) &lt;strong&gt;people other than&#xA;  the operator may not be used&lt;/strong&gt; in lieu of the operator for maintaining&#xA;  visual line of sight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But also note that this does not apply if:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the aircraft is operated in accordance with a community-based set of&#xA;  safety guidelines and within the programming of a nationwide&#xA;  community-based organization;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The above is from the linked NPRM released in June 2014. &lt;a href=&quot;https://www.faa.gov/regulations_policies/rulemaking/media/021515_suas_summary.pdf&quot;&gt;The latest NPRM from February 2015&lt;/a&gt; has the same requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So members of an organization like &lt;a href=&quot;http://www.modelaircraft.org/&quot;&gt;AMA&lt;/a&gt; are exempt from that rule. The AMA &lt;a href=&quot;https://www.modelaircraft.org/files/550.pdf&quot;&gt;requires a spotter&lt;/a&gt; to be used when flying FPV.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:06:42.083" LastActivityDate="2015-04-17T02:06:42.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14118" PostTypeId="5" CreationDate="2015-04-17T02:11:00.200" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:11:00.200" LastActivityDate="2015-04-17T02:11:00.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14119" PostTypeId="4" CreationDate="2015-04-17T02:11:00.200" Score="0" Body="Use in conjunction with a country tag, if a [regulations-country] tag does not yet exist" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2021-03-09T18:24:54.127" LastActivityDate="2021-03-09T18:24:54.127" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14120" PostTypeId="5" CreationDate="2015-04-17T02:12:58.117" Score="0" Body="&lt;p&gt;The &lt;strong&gt;Airbus A320&lt;/strong&gt; is a family of short-to-medium-to-relatively-long-range narrowbody (single-aisle) twinjets produced by &lt;a href=&quot;/questions/tagged/airbus&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus&lt;/a&gt; since 1986; until Airbus’s 2018 acquisition of the Bombardier CSeries (now the &lt;a href=&quot;/questions/tagged/airbus-a220&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a220&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a220&lt;/a&gt;, which complements the smaller end of the A320 product line), the A320 family were the European consortium’s &lt;em&gt;only&lt;/em&gt; narrowbody airliners.  They are also Airbus’s best-selling airliners, with over 8,000 delivered and several thousand more on order.  The A320 family competes head-to-head with the similarly-popular &lt;a href=&quot;/questions/tagged/boeing-737&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-737&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-737&lt;/a&gt; (from which it can be distinguished by its blunt, rounded nose; the 737, in contrast, still has the sharply-pointed nose that it inherited, indirectly, from the &lt;a href=&quot;/questions/tagged/boeing-707&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-707&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-707&lt;/a&gt;), and various members of the family also compete against the &lt;a href=&quot;/questions/tagged/boeing-757&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-757&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-757&lt;/a&gt;, the &lt;a href=&quot;/questions/tagged/embraer-e-jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;embraer-e-jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;embraer-e-jet&lt;/a&gt;, and the remaining members of the &lt;a href=&quot;/questions/tagged/dc-9-family&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-9-family&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-9-family&lt;/a&gt;; in its early years, the A320 also competed against the older &lt;a href=&quot;/questions/tagged/bac-one-eleven&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bac-one-eleven&amp;#39;&quot; rel=&quot;tag&quot;&gt;bac-one-eleven&lt;/a&gt;, which it mostly replaced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the &lt;a href=&quot;/questions/tagged/airbus-a300&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a300&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a300&lt;/a&gt; (and its shorter, longer-range derivative, the &lt;a href=&quot;/questions/tagged/airbus-a310&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a310&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a310&lt;/a&gt;) entered service, Airbus began to look at a narrowbody with which to tap the lucrative short-haul market then served primarily by the 737 and DC-9.  Work began in June 1977, and the aircraft on the drawing boards was specifically tailored to outmatch the 737, being faster (with a cruising speed of up to mach 0.84, although the aircraft actually produced would be slower, typically cruising at mach 0.78), more fuel-efficient (it was designed from the start to use the General Electric/SNECMA CFM56 high-&lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt; &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt;, while the then-current 737 version, the 737-200, used the older, louder, and thirstier Pratt &amp;amp; Whitney JT8D low-bypass turbofan; however, by the time the A320 was ready to go, &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt; had themselves released a CFM56-powered 737, the 737-300, which flew three years &lt;em&gt;before&lt;/em&gt; the A320), lighter (making considerable use of &lt;a href=&quot;/questions/tagged/composite-materials&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;composite-materials&amp;#39;&quot; rel=&quot;tag&quot;&gt;composite-materials&lt;/a&gt;, as opposed to the all-metal 737), easier to fly (using a “glass cockpit” - an innovation later adopted by the 737 - which uses electronic display screens instead of ye olde mechanical gauges, and having a &lt;a href=&quot;/questions/tagged/sidestick&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;sidestick&amp;#39;&quot; rel=&quot;tag&quot;&gt;sidestick&lt;/a&gt; rather than a conventional control yoke, which Airbus believed would make the flight controls more ergonomic to use), and safer (the A320 was the world’s first &lt;a href=&quot;/questions/tagged/fly-by-wire&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fly-by-wire&amp;#39;&quot; rel=&quot;tag&quot;&gt;fly-by-wire&lt;/a&gt; airliner, incorporating flight-envelope protections designed to keep the pilot from doing things like &lt;a href=&quot;/questions/tagged/stall&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stall&amp;#39;&quot; rel=&quot;tag&quot;&gt;stall&lt;/a&gt;ing the plane) than its Boeing counterpart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Work proceeded somewhat slowly, amid disagreements on the precise role of the aircraft (which officially received the &lt;em&gt;A320&lt;/em&gt; designation in 1981), who would get to build it, and how it would be paid for; by the time the A320 was officially launched in March 1984, the 737-300 had already flown, while the A320 had yet to even start production of its first prototype.  However, after the A320’s launch, the pace of things picked up, and A320 #1 rolled off the line on 14 February 1987, making its first flight eight days later.  After a rigorous &lt;a href=&quot;/questions/tagged/flight-testing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-testing&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-testing&lt;/a&gt; programme, the A320 received its type certificate in February 1988, and entered service with Air France the following month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are seven major members of the A320 family, in two main groups…&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ceo (Current Engine Option) variants&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These variants use GE/SNECMA CFM56, International Aero Engines (IAE) V2500 (only available for the A319ceo through A321ceo), or (as an option on the A318) Pratt &amp;amp; Whitney PW6000 engines.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;em&gt;A318&lt;/em&gt;, which first flew in January 2002 and entered service the following year with U.S. operator Frontier Airlines, is the smallest A320 version, and the smallest airliner Airbus has ever produced (smaller even than the A220-100); it was created by shrinking the A319 (see below), itself a shrink of the baseline A320 (the A318’s resulting very short &lt;a href=&quot;/questions/tagged/fuselage&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuselage&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuselage&lt;/a&gt; necessitated an enlarged &lt;a href=&quot;/questions/tagged/vertical-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vertical-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;vertical-stabilizer&lt;/a&gt; in order to maintain adequate &lt;a href=&quot;/questions/tagged/stability&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stability&amp;#39;&quot; rel=&quot;tag&quot;&gt;stability&lt;/a&gt; in flight).  Carrying a maximum of 132 passengers (although a more typical figure is 107), it has a maximum range of 5,700 km (3,100 nmi).  Unlike the other members of the A320 family, the A318 has the ability to make an &lt;a href=&quot;/questions/tagged/approach&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;approach&amp;#39;&quot; rel=&quot;tag&quot;&gt;approach&lt;/a&gt; at a considerably steeper angle than usual if necessary, making it especially useful for service to some inner-city airports where shooting an approach at a more usual angle would entail flying through buildings.  Despite this unique (for an A320) capability, the A318 proved too small to be practical for most airlines’ use, and only 80 were ever built (of which 65 remain in service), the last in 2015 (and the penultimate A318 two years before that); although Airbus still offers the A318, none have been ordered since.  As a result, it is the only A320 variant not to have a neo version (although Airbus has not ruled out the possibility of an A318neo should anyone express an interest for one), and, thus, the only ceo A320 that does not need to be suffixed with the -ceo suffix for disambiguation purposes.  It competes with the similarly-poorly-selling 737-600.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A319ceo&lt;/em&gt; (often simply the &lt;em&gt;A319&lt;/em&gt;) first flew in August 1995, entering service the following year with Swissair.  It is a direct shrink of the baseline A320, carrying up to 156 passengers, although 124 is more usual (and was itself later shrunk again, into the A318, as mentioned above).  As the fuselage was shrunk, but the &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s (and the &lt;a href=&quot;/questions/tagged/fuel-tank&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel-tank&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel-tank&lt;/a&gt;s carried therein) stayed the same size, the A319ceo is the longest-range ceo A320, able to fly up to 6,950 km (3,750 nmi) nonstop.  1,479 have been delivered as of the end of 2019 (1,424 of them still flying), with an additional seven on order.  It competes with the 737-700 and with the DC-9-95 (alias Boeing 717).&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A320ceo&lt;/em&gt; (frequently referred to as just the &lt;em&gt;A320&lt;/em&gt;) was the first member of the family to be developed, taking to the air, as previously mentioned, in February 1987, and entering service with Air France the following year.  After building the first 21 A320s, designated &lt;em&gt;A320-100&lt;/em&gt;, Airbus tweaked the design and came up with the &lt;em&gt;A320-200&lt;/em&gt;, adding small arrowhead-shaped wingtip fences for improved efficiency and larger fuel tanks for increased range - up to 6,100 km (3,300 nmi) in a single bound with up to 186 passengers sardined in, although the A320 usually carries closer to 150.  With 4,749 delivered (4,396 of them yet in service) and 21 orders outstanding, the A320ceo accounts for more than half of the total market for the A320 family’s ceo variants.  Its main competitor is the 737-800.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A321ceo&lt;/em&gt; (better known as simply the &lt;em&gt;A321&lt;/em&gt;), which first flew in March 1993 and entered service the following year with &lt;a href=&quot;/questions/tagged/lufthansa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lufthansa&amp;#39;&quot; rel=&quot;tag&quot;&gt;lufthansa&lt;/a&gt;, is the largest of the ceo variants, carrying 236 passengers in sardine mode (or 185 if you want to give them room to breathe).  A direct stretch of the baseline A320, the first 90 A321s (designated &lt;em&gt;A321-100&lt;/em&gt;) had a correspondingly-shorter range, as their fuel tanks had not been enlarged to compensate.  Airbus fixed this issue with the &lt;em&gt;A321-200&lt;/em&gt;, introduced in 1995, which restored the range to 5,900 km (3,200 nmi), &lt;em&gt;almost&lt;/em&gt; as far as the A320ceo, by adding auxiliary fuel tanks in the aft cargo hold (although these can be removed if an operator is willing to sacrifice range in order to carry more &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt; and/or &lt;a href=&quot;/questions/tagged/baggage&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;baggage&amp;#39;&quot; rel=&quot;tag&quot;&gt;baggage&lt;/a&gt;), plus uprated engines and a reinforced structural frame to allow it to safely carry the extra &lt;a href=&quot;/questions/tagged/fuel&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel&lt;/a&gt;.  As of the end of 2019, 1,753 A321ceos have been delivered (1,725 of which remain in service), with 38 orders to go.  It competes primarily with the 737-900, 757-300, and DC-9-80 and -93 (alias MD-80 and MD-90, respectively).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;neo (New Engine Option) variants&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These variants use either the CFM International (GE/SNECMA) LEAP engine, or else the Pratt &amp;amp; Whitney PW1000G &lt;a href=&quot;/questions/tagged/geared-turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;geared-turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;geared-turbofan&lt;/a&gt;; these engines (especially the PW1000G, the largest and highest-thrust geared turbofan yet) experienced a rash of teething troubles (leading to a nickname of “&lt;em&gt;No&lt;/em&gt; Engine Option” for the aircraft sitting on the ramp with their engines removed for &lt;a href=&quot;/questions/tagged/maintenance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;maintenance&amp;#39;&quot; rel=&quot;tag&quot;&gt;maintenance&lt;/a&gt;), but these have mostly been worked out.  They also feature a large, prominent &lt;a href=&quot;/questions/tagged/winglet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;winglet&amp;#39;&quot; rel=&quot;tag&quot;&gt;winglet&lt;/a&gt; (which Airbus marketing wants you to call a &lt;em&gt;sharklet&lt;/em&gt;) on the tip of each wing, replacing the older wingtip fences; they compete (&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX_groundings&quot; rel=&quot;nofollow noreferrer&quot;&gt;albeit not currently&lt;/a&gt;) with the 737 MAX series.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;As mentioned above, there are currently no plans to build an &lt;em&gt;A318neo&lt;/em&gt;, although Airbus remains willing to do so should it find a customer.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A319neo&lt;/em&gt; first flew at the end of March 2017, but has not yet entered commercial service (despite having received type certification in December 2018); when it does, it should typically carry 140 passengers, or up to a maximum of 160, on legs of up to 6,950 km (3,750 nmi), the same range as the A319ceo (the range non-increase presumably being due to the typical capacity being bumped up a tad).  Like what will probably (if not cancelled before then) become its primary competitor, the 737 MAX 7, the A319neo has been selling almost as poorly as the A318, with only two delivered so far (both of them configured as large &lt;a href=&quot;/questions/tagged/private-jets&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;private-jets&amp;#39;&quot; rel=&quot;tag&quot;&gt;private-jets&lt;/a&gt;, rather than as airliners) and 35 orders still pending.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A320neo&lt;/em&gt; was the first neo variant, making its maiden flight on 25 September 2014 and entering service (with Lufthansa) in January 2016.  It carries 165 passengers in a typical configuration, although it can sardine in up to 195.  Unlike the A319neo, it &lt;em&gt;does&lt;/em&gt; have an increased range compared to its ceo variant, being able to fly up to 6,500 km (3,300 nmi) at a time.  Also unlike the A319neo, the A320neos have been selling like 737s, with 894 delivered as of the end of 2019 and 3,002 orders still to go.  It competes mainly with the 737 MAX 8 (or, at least, it will when Boeing’s aircraft stops being grounded).&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;A321neo&lt;/em&gt; is the largest (typical capacity 206 passengers, and able to carry up to 240 in full-on sardine mode) and longest-range (7,400 km [4,000 nmi]) A320 yet; it took to the air in February 2016, received type certification (following a lengthy delay when the prototype was in for repairs after suffering a &lt;a href=&quot;/questions/tagged/tailstrike&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tailstrike&amp;#39;&quot; rel=&quot;tag&quot;&gt;tailstrike&lt;/a&gt;) in December 2016 (when powered by PW1000G engines) and March 2017 (when powered by LEAP engines), and entered service in May 2017 with Virgin America.  A subvariant which gains even more range by using three auxiliary fuel tanks and carrying fewer passengers, the &lt;em&gt;A321neoLR&lt;/em&gt; (&lt;em&gt;&lt;strong&gt;L&lt;/strong&gt;ong &lt;strong&gt;R&lt;/strong&gt;ange&lt;/em&gt;), entered service in November 2018, and a yet-longer-range-still variant, the &lt;em&gt;A321neoXLR&lt;/em&gt; (&lt;em&gt;e&lt;strong&gt;X&lt;/strong&gt;tra &lt;strong&gt;L&lt;/strong&gt;ong &lt;strong&gt;R&lt;/strong&gt;ange&lt;/em&gt;, &lt;em&gt;e&lt;strong&gt;X&lt;/strong&gt;tremely &lt;strong&gt;L&lt;/strong&gt;ong &lt;strong&gt;R&lt;/strong&gt;ange&lt;/em&gt;, or &lt;em&gt;e&lt;strong&gt;X&lt;/strong&gt;tended &lt;strong&gt;L&lt;/strong&gt;ong &lt;strong&gt;R&lt;/strong&gt;ange&lt;/em&gt;) is under study.  290 A321neos have been delivered so far, and 2,965 remain on order.  Its main competitor (whenever it gets ungrounded) is the 737 MAX 9.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See Wikipedia for more about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A320 family in general, and the A320ceo variants in particular&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A318&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A318&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A319&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A319ceo&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A321&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A321ceo&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A320neo variants&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2020-01-18T07:02:28.077" LastActivityDate="2020-01-18T07:02:28.077" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14121" PostTypeId="4" CreationDate="2015-04-17T02:12:58.117" Score="0" Body="The Airbus A320 family is a series of twin-engine, single-aisle passenger jets produced from 1986-present. Different versions can typically carry from 107 to 220 passengers." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-05-22T06:49:10.187" LastActivityDate="2019-05-22T06:49:10.187" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14122" PostTypeId="5" CreationDate="2015-04-17T02:14:02.473" Score="0" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=698c0142afb3ae01b23711087ec558e7&amp;amp;mc=true&amp;amp;node=pt14.1.1&amp;amp;rgn=div5&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt;, &lt;code&gt;Commercial Operations&lt;/code&gt; are operations that engage in the carriage by aircraft in air commerce of persons or property for compensation or hire, other than as an air carrier or foreign air carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For air carrier operations see &lt;a href=&quot;/questions/tagged/airline-operations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airline-operations&amp;#39;&quot; rel=&quot;tag&quot;&gt;airline-operations&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="12720" LastEditDate="2016-03-05T18:59:50.543" LastActivityDate="2016-03-05T18:59:50.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14123" PostTypeId="4" CreationDate="2015-04-17T02:14:02.473" Score="0" Body="Questions pertaining to the operation of aircraft for commercial purposes." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:14:02.473" LastActivityDate="2015-04-17T02:14:02.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14124" PostTypeId="5" CreationDate="2015-04-17T02:15:44.650" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;nofollow&quot;&gt;Airbus A380&lt;/a&gt; is a four-engine, double-deck, wide-body aircraft produced by Airbus since 2005 (it first flew commercially in 2007). In a typical configuration (according to Airbus) it can carry 525 passengers but it has been shown to be capable of carrying over 850 with an 'economy only' configuration. The A380 requires upgraded airport facilities to allow ground operations, including ramp space, reinforced pavements and loading vehicles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of mid-2015 it is the largest aircraft in production in the world.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="62" LastEditDate="2015-05-20T20:19:10.427" LastActivityDate="2015-05-20T20:19:10.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14125" PostTypeId="4" CreationDate="2015-04-17T02:15:44.650" Score="0" Body="The Airbus A380 is a four-engine, double-deck, wide-body airliner that is currently (mid-2015) the largest production aircraft in the world" OwnerUserId="1696" LastEditorUserId="62" LastEditDate="2015-05-20T20:19:10.427" LastActivityDate="2015-05-20T20:19:10.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14126" PostTypeId="5" CreationDate="2015-04-17T02:16:36.850" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:16:36.850" LastActivityDate="2015-04-17T02:16:36.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14127" PostTypeId="4" CreationDate="2015-04-17T02:16:36.850" Score="0" Body="Questions about different techniques that pilots may use when flying." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:16:36.850" LastActivityDate="2015-04-17T02:16:36.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14128" PostTypeId="5" CreationDate="2015-04-17T02:16:56.517" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:16:56.517" LastActivityDate="2015-04-17T02:16:56.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14129" PostTypeId="4" CreationDate="2015-04-17T02:16:56.517" Score="0" Body="Questions about the software used in aviation systems." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:16:56.517" LastActivityDate="2015-04-17T02:16:56.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14130" PostTypeId="5" CreationDate="2015-04-17T02:19:00.393" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:19:00.393" LastActivityDate="2015-04-17T02:19:00.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14131" PostTypeId="4" CreationDate="2015-04-17T02:19:00.393" Score="0" Body="Use only when final reports are released or for the process of investigating accidents. Questions inviting speculation or opinions are off-topic." OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2020-01-27T22:05:57.960" LastActivityDate="2020-01-27T22:05:57.960" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14132" PostTypeId="5" CreationDate="2015-04-17T02:19:45.313" Score="0" Body="&lt;p&gt;&lt;em&gt;Lift&lt;/em&gt; is the upwards force exerted on a body (such as an aircraft) by the surrounding fluid (which, for an aircraft, is generally air).  There are three main types of lift, but of the most interest for heavier-than-air aircraft is &lt;em&gt;dynamic lift&lt;/em&gt;, which occurs when an object moves through a homogeneous fluid which surrounds it on all sides.  The other two types of lift are &lt;em&gt;aerostatic lift&lt;/em&gt;, also called &lt;em&gt;buoyancy&lt;/em&gt; (which occurs when the object in question has a lower average density than that of the surrounding fluid, and is mainly of interest for balloons and &lt;a href=&quot;/questions/tagged/dirigible&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dirigible&amp;#39;&quot; rel=&quot;tag&quot;&gt;dirigible&lt;/a&gt;s), and &lt;em&gt;planing lift&lt;/em&gt; (which occurs when only one side of the object is in contact with the fluid, and is mainly of interest for some watercraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dynamic lift is produced by a combination of several processes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the aircraft has a positive &lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt;, it deflects the air it hits downwards, which, in turn, pushes the aircraft upwards.&lt;/li&gt;&#xA;&lt;li&gt;Most aircraft have wings with a &lt;em&gt;cambered&lt;/em&gt; (curved) upper surface, with the greatest curvature being at or just behind the wing's leading edge, which limits the space available for the air passing over the top of the wing and forces it to move faster than the air passing underneath the wing; this decreases the air pressure above the wing relative to that underneath, causing the wing to be sucked upwards.&lt;/li&gt;&#xA;&lt;li&gt;The air moving over the aft portion of the wing moves downwards as it does so in order to follow the curve of the wing's upper surface; when this air reaches the wing's trailing edge, it continues to move downwards, pushing the wing upwards.&lt;/li&gt;&#xA;&lt;li&gt;Some &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; aircraft are shaped so that the &lt;a href=&quot;/questions/tagged/shock-wave&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;shock-wave&amp;#39;&quot; rel=&quot;tag&quot;&gt;shock-wave&lt;/a&gt;s generated by supersonic flight are stronger under the aircraft than above it and are partially trapped under the aircraft, forcing it upwards.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2018-07-01T01:57:53.527" LastActivityDate="2018-07-01T01:57:53.527" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14133" PostTypeId="4" CreationDate="2015-04-17T02:19:45.313" Score="0" Body="The force acting on an aircraft in opposition to gravity which keeps the aircraft in the air." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:19:45.313" LastActivityDate="2015-04-17T02:19:45.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14134" PostTypeId="5" CreationDate="2015-04-17T02:20:23.007" Score="0" Body="&lt;p&gt;Noise, specifically sound noise, typically caused by vibration. Typically, this is known for causing passenger discomfort, and excess wear and tear on the airframe. &lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="11423" LastEditDate="2015-10-01T01:30:58.500" LastActivityDate="2015-10-01T01:30:58.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14135" PostTypeId="4" CreationDate="2015-04-17T02:20:23.007" Score="0" Body="Questions related to aviation sound noise or regulations thereof." OwnerUserId="1696" LastEditorUserId="11423" LastEditDate="2015-10-01T01:30:36.230" LastActivityDate="2015-10-01T01:30:36.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14136" PostTypeId="5" CreationDate="2015-04-17T02:22:18.157" Score="0" Body="&lt;p&gt;The &lt;strong&gt;Boeing 747&lt;/strong&gt; is a four-engined widebody jetliner (&quot;Jumbo Jet&quot;) produced by &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt;. &#xA; The first-ever widebody (twin-aisle) airliner, it first flew in February 1969 and entered commercial airline service in January 1970.  With a maximum passenger capacity of 400 to 660 (depending on the model), it was also the largest and highest-capacity airliner until the &lt;a href=&quot;/questions/tagged/airbus-a380&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a380&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a380&lt;/a&gt; was introduced in 2007.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 was the first jetliner to have a double passenger deck; the lower deck extends the full length of the pressurized cabin, while the upper deck terminates either in front of (most older-series 747s) or above (a few 747s from older series, plus all newer models) the wings, giving the 747 an instantly-recognizable hump in front of the wings.  Boeing chose this configuration so that the 747 could be easily converted to a &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt; aircraft by adding a cargo door in the nose, as, when they were designing the 747 in the 1960s, it was believed that the long-haul passenger market would soon be taken over by &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; airliners (such as the &lt;a href=&quot;/questions/tagged/concorde&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;concorde&amp;#39;&quot; rel=&quot;tag&quot;&gt;concorde&lt;/a&gt; and Boeing's own never-built 2707), which were all the rage at the time.  Although this did not, for the most part, happen, a large number of 747s have nevertheless been converted to cargo aircraft, and many more came from the factory in cargo configuration.  The 747's &lt;a href=&quot;/questions/tagged/cockpit&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cockpit&amp;#39;&quot; rel=&quot;tag&quot;&gt;cockpit&lt;/a&gt; is at the front of the upper deck; the space behind the cockpit was used for a passenger lounge in the very first 747s, but was later used by most airlines to add additional (usually first- or business-class) seating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 was also the first jetliner powered by a high-bypass &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt; engine (a turbofan with a &lt;a href=&quot;/questions/tagged/bypass-ratio&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bypass-ratio&amp;#39;&quot; rel=&quot;tag&quot;&gt;bypass-ratio&lt;/a&gt; greater than 5:1), rather than the &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt;s or low-bypass turbofans used by previous jetliners (although not the first aircraft overall to use high-bypass turbofans; &lt;em&gt;that&lt;/em&gt; honor belongs to Lockheed's C-5 Galaxy military transport).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 has had six major versions over the years:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 747-100 was the first 747 to enter service; 206 were built.  168 of these were vanilla -100s, 29 were the higher-passenger-capacity -100SR (Short Range)/-100BSR variant developed especially for the Japanese market, and the remaining nine were long-range 747-100Bs (based on the 747-100SR, but with extra fuel capacity instead of extra passenger capacity).  Most 747-100s had the original short upper deck (terminating in front of the wings), but two of the very last -100BSRs (built in 1986) were delivered with the stretched upper deck introduced with the 747-300.  One vanilla 747-100 and one 747-100SR were modified by &lt;a href=&quot;/questions/tagged/nasa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;nasa&amp;#39;&quot; rel=&quot;tag&quot;&gt;nasa&lt;/a&gt; to ferry the &lt;a href=&quot;/questions/tagged/space-shuttle&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;space-shuttle&amp;#39;&quot; rel=&quot;tag&quot;&gt;space-shuttle&lt;/a&gt; from place to place.  No 747-100s remain in commercial operation, the last having been retired by Iran Air in 2014.&lt;/li&gt;&#xA;&lt;li&gt;The 747-100 had barely enough range for intercontinental flights, leading to the development of the 747-200; introduced in 1971, the -200 has more powerful engines and a greater fuel capacity than the -100, giving it a considerably increased range.  Most -200s have the original short upper deck, but some later -200s were sold with the -300-length stretched upper deck.  747-200 production ended in 1991 after 393 had been built.  Since Iran Air's retirement of its passenger 747-200s in May 2016, none of the type remain in commercial passenger service; eight -200s are still flying as freighters, while two heavily-modified -200s are operated by the &lt;a href=&quot;/questions/tagged/us-air-force&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;us-air-force&amp;#39;&quot; rel=&quot;tag&quot;&gt;us-air-force&lt;/a&gt; under the &quot;Boeing VC-25A&quot; designation as the primary air transport for the president of the United States of America (these aircraft are popularly, though not quite accurately, known as &lt;a href=&quot;/questions/tagged/air-force-one&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;air-force-one&amp;#39;&quot; rel=&quot;tag&quot;&gt;air-force-one&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;The 747SP (Special Performance), a long-range version with a shortened fuselage, was introduced into service in 1976; 44 were built from 1974 through 1982, plus one last 747SP in 1989.  It is the smallest and lightest 747, and the first in which the upper deck extends above the wings (the SP has the original short upper deck, but it nevertheless extends over the wings due to the shortening of the forward fuselage).  The last 747SP in commercial passenger service, belonging to (again) Iran Air, was retired in 2016, but several continue to fly as government or VIP transports, plus three used by Pratt &amp;amp; Whitney as engine testbeds and one heavily-modified 747SP operated by NASA and the German Aerospace Center as the platform for an airborne infrared telescope (the Stratospheric Observatory for Infrared Astronomy, or SOFIA).&lt;/li&gt;&#xA;&lt;li&gt;The 747-300 was introduced into service in 1983, and was the first model of 747 to incorporate the new, stretched upper deck (after the 747SP proved that having the rear portion of the 747's hump extend over the wings would not negatively affect the aircraft's aerodynamics); the stretched upper deck was also later offered as an option on post-1980 747-100s and -200s.  Only 81 -300s were produced before production stopped in 1990 (77 of the basic 747-300, of which five remain in service today, plus four high-capacity 747-300SRs for the Japanese market), it having been overtaken after just two years by the 1985 announcement of...&lt;/li&gt;&#xA;&lt;li&gt;the 747-400, which entered service in 1989, featuring a larger wing, more efficient engines, and increased fuel capacity, which combine to give it a considerably longer range than any previous 747.  Other improvements include a revamped cabin interior and a so-called &quot;glass cockpit&quot; (using electronic displays rather than the traditional sea of mechanical gauges and dials), the latter allowing the -400 to fly with a two-person flight crew, eliminating the need for a &lt;a href=&quot;/questions/tagged/flight-engineer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-engineer&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-engineer&lt;/a&gt;.  Passenger -400s, and -400s converted from passenger to freight service, have the -300-length upper deck, while those delivered as freighters have the shorter, -100-length upper deck.  694 747-400s of various flavors were built (the most of any 747 version) before the production line shut down in 2009, over 300 of which remain in service.&lt;/li&gt;&#xA;&lt;li&gt;The latest version is the &lt;a href=&quot;/questions/tagged/boeing-747-8&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747-8&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747-8&lt;/a&gt;, a stretched version with yet-more-efficient engines that entered service in 2011.  The passenger version of the 747-8, the -8I (Intercontinental), became the longest airliner in the world when it was introduced by &lt;a href=&quot;/questions/tagged/lufthansa&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lufthansa&amp;#39;&quot; rel=&quot;tag&quot;&gt;lufthansa&lt;/a&gt; in June 2012, surpassing the &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;.  As with the -400, -8s delivered as passenger aircraft have the stretched upper deck, while those delivered as freighters have the short upper deck.  As of September 2018, 150 -8s have been ordered and 129 delivered, with about two-thirds being cargo aircraft.  Boeing has had great difficulty selling the 747-8I amidst two general trends: one toward smaller jets, and the other toward twinjets (such as the company's own &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information, see Wikipedia's articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 747&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747SP&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 747SP&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-400&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 747-400&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 747-8&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="33692" LastEditDate="2019-08-20T14:27:41.597" LastActivityDate="2019-08-20T14:27:41.597" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14137" PostTypeId="4" CreationDate="2015-04-17T02:22:18.157" Score="0" Body="A medium- to long-range four-engine wide-body jetliner (the original &quot;Jumbo Jet&quot;) introduced into commercial service in 1970, easily recognizable by its distinctive hump forward of the wings.  Different versions typically seat between 266 and 660 passengers." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2018-10-25T11:17:19.253" LastActivityDate="2018-10-25T11:17:19.253" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14138" PostTypeId="5" CreationDate="2015-04-17T02:22:52.767" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:22:52.767" LastActivityDate="2015-04-17T02:22:52.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14139" PostTypeId="4" CreationDate="2015-04-17T02:22:52.767" Score="0" Body="Questions regarding the distance separating aircraft during flight." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:22:52.767" LastActivityDate="2015-04-17T02:22:52.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14140" PostTypeId="5" CreationDate="2015-04-17T02:26:36.623" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:26:36.623" LastActivityDate="2015-04-17T02:26:36.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14141" PostTypeId="4" CreationDate="2015-04-17T02:26:36.623" Score="0" Body="The standard pattern that traffic follows when landing at or taking off from an airport, or when performing touch-and-goes. The pattern - or circuit - can use either right-hand or left-hand turns and has five segments: upwind, crosswind, downwind, base, and final." OwnerUserId="1696" LastEditorUserId="62" LastEditDate="2016-05-23T13:50:22.330" LastActivityDate="2016-05-23T13:50:22.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14142" PostTypeId="5" CreationDate="2015-04-17T02:28:23.003" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:28:23.003" LastActivityDate="2015-04-17T02:28:23.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14143" PostTypeId="4" CreationDate="2015-04-17T02:28:23.003" Score="0" Body="The essential permission for a pilot to be authorized to operate an aircraft in US airspace." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:28:23.003" LastActivityDate="2015-04-17T02:28:23.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14144" PostTypeId="5" CreationDate="2015-04-17T02:28:57.693" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:28:57.693" LastActivityDate="2015-04-17T02:28:57.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14145" PostTypeId="4" CreationDate="2015-04-17T02:28:57.693" Score="0" Body="The category of lighter-than-air flight where gas or hot air provides buoyancy " OwnerUserId="1696" LastEditorUserId="3504" LastEditDate="2016-05-01T15:39:32.460" LastActivityDate="2016-05-01T15:39:32.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14146" PostTypeId="5" CreationDate="2015-04-17T02:29:22.850" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:29:22.850" LastActivityDate="2015-04-17T02:29:22.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14147" PostTypeId="4" CreationDate="2015-04-17T02:29:22.850" Score="0" Body="Questions about the theoretical aspects of aviation." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:29:22.850" LastActivityDate="2015-04-17T02:29:22.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14148" PostTypeId="5" CreationDate="2015-04-17T02:30:18.790" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:30:18.790" LastActivityDate="2015-04-17T02:30:18.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14149" PostTypeId="4" CreationDate="2015-04-17T02:30:18.790" Score="0" Body="A set of rotating blades that extracts power from a flow. In aviation this primarily refers to the section of a gas turbine that extracts power from the combusted gases, as part of a turboshaft, turboprop, or jet engine." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-30T14:55:07.957" LastActivityDate="2015-04-30T14:55:07.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14150" PostTypeId="5" CreationDate="2015-04-17T02:30:59.513" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:30:59.513" LastActivityDate="2015-04-17T02:30:59.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14151" PostTypeId="4" CreationDate="2015-04-17T02:30:59.513" Score="0" Body="Questions about maintaining things such as airports and associated infrastructure. Questions specifically about maintaining aircraft should get the [tag:aircraft-maintenance] tag instead." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-07-08T14:40:28.997" LastActivityDate="2016-07-08T14:40:28.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14152" PostTypeId="5" CreationDate="2015-04-17T02:32:16.823" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:32:16.823" LastActivityDate="2015-04-17T02:32:16.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14153" PostTypeId="4" CreationDate="2015-04-17T02:32:16.823" Score="0" Body="The physics of maintaining a specific state in the dynamic system of aircraft flight." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:32:16.823" LastActivityDate="2015-04-17T02:32:16.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14154" PostTypeId="5" CreationDate="2015-04-17T02:33:58.803" Score="0" Body="&lt;p&gt;The &lt;em&gt;Boeing 787&lt;/em&gt;, or &lt;em&gt;Dreamliner&lt;/em&gt;, is a long-range widebody twinjet airliner produced by &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt; since 2007.  It is Boeing’s newest airliner (serving as a replacement for the &lt;a href=&quot;/questions/tagged/boeing-767&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-767&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-767&lt;/a&gt;, the company’s first twin-engine widebody), and also their first built primarily from &lt;a href=&quot;/questions/tagged/composite-materials&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;composite-materials&amp;#39;&quot; rel=&quot;tag&quot;&gt;composite-materials&lt;/a&gt; rather than the traditional aluminium alloys.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing started casting around for a successor to the 767 in the late 1990s, initially settling on the “Sonic Cruiser”, which would have carried the same number of passengers as the 767, using the same amount of fuel, but at a 15%-higher speed (approximately mach 0.98).  However, rising fuel costs in the early 2000s, coupled with the post-September-2001 downturn in the airline industry, left the Sonic Cruiser in want of a market, and Boeing cancelled the project in December 2002, deciding to instead produce an airliner that would travel the same speed as everyone else’s, but do so more &lt;em&gt;efficiently&lt;/em&gt;.  This was named the &lt;em&gt;7E7&lt;/em&gt; (soon to become the familiar &lt;em&gt;787&lt;/em&gt;), and a public naming competition officially dubbed it the &lt;em&gt;Dreamliner&lt;/em&gt; in July 2003.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new airliner, unlike Boeing’s previous offerings, was to be made mostly from large, cylindrical sections of carbon-fiber-reinforced-polymer (CFRP), a composite material that is essentially a mesh of carbon fibers embedded in very strong glue.  CFRP is lighter for a given strength than most metal components would be, which saves weight (although it turns out that the 787 is actually &lt;em&gt;heavier&lt;/em&gt; than the 767, due to its greater size); however, metal components are still used where their other advantages outweigh (so to speak) their greater weight (for instance, the engines are mainly titanium, due to its extreme strength and temperature resistance, while the leading edges of the wing and tail are still primarily made from aluminium alloys).  These cylindrical sections would, instead of arriving empty and then being decked out with their bells and whistles at the final assembly location, be almost fully outfitted by subcontractors in various parts of the globe, and only &lt;em&gt;then&lt;/em&gt; shipped for final assembly (Boeing had been subcontracting out various tasks ever since the 767, but never to &lt;em&gt;this&lt;/em&gt; degree); to help move large, nearly-complete fuselage sections and wings around, Boeing tore apart a &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt; and rebuilt it into the &lt;a href=&quot;/questions/tagged/boeing-dreamlifter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-dreamlifter&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-dreamlifter&lt;/a&gt;, later doing the same with three more 747s.  Other advances included new, more efficient engines, a lighter lithium-ion &lt;a href=&quot;/questions/tagged/battery&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;battery&amp;#39;&quot; rel=&quot;tag&quot;&gt;battery&lt;/a&gt; system (this will become important later on), and various aerodynamic optimisations throughout the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a consequence of all this new ground being broken, the 787’s development costs grew extremely large (exceeding those of the &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt; by a &lt;em&gt;full order of magnitude&lt;/em&gt;, even accounting for inflation), and the programme was badly delayed compared to initial projections; originally scheduled to take to the air in August 2007, the 787’s maiden flight ultimately did not occur until December 2009, and its &lt;a href=&quot;/questions/tagged/flight-testing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flight-testing&amp;#39;&quot; rel=&quot;tag&quot;&gt;flight-testing&lt;/a&gt; programme, originally scheduled for an optimistic 8½ months, ended up taking eighteen.  Certification was finally granted in August 2011, and the first 787 was delivered to All Nippon Airways on 25 September of that year, entering revenue service on 26 October 2011, three years behind schedule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the 787 duly met, or, more often, exceeded, performance expectations, it was also plagued with various technical difficulties throughout its first year and a half in service.  First came problems with its &lt;a href=&quot;/questions/tagged/apu&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;apu&amp;#39;&quot; rel=&quot;tag&quot;&gt;apu&lt;/a&gt;, when it was found to be prone to overheating and deforming when shut down; next came a spate of engine failures on 787s with General Electric GEnx engines.  January 2013 brought issues with &lt;a href=&quot;/questions/tagged/fuel&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuel&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuel&lt;/a&gt; leakage, but this was overshadowed by a much worse problem: the aircraft’s lithium-ion batteries (remember those?) started spontaneously catching fire, sometimes during flight, and the 787 was grounded worldwide for three months until the cause of the fires (internal short-circuiting) was found and corrected.  Since its early teething troubles, fortunately enough, the 787 has become better-behaved, with no other issues of a similar magnitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three commercial versions of the 787:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;em&gt;787-8&lt;/em&gt;, the first model to fly and the first to enter service, is the smallest 787, with a typical seating capacity of 242 passengers (although it can squeeze in up to 359 if the passengers are packed in like sardines).  It has a range of 13,620 km (7,355 nmi) when carrying 242 passengers and luggage.  360 have been delivered through the end of 2018, with 84 unfilled orders.&lt;/li&gt;&#xA;&lt;li&gt;The larger &lt;em&gt;787-9&lt;/em&gt; first flew in September 2013, and entered revenue service with Air New Zealand on 9 August 2014.  Its 6.1-meter-(20-foot)-longer fuselage lets it carry 290 passengers in a typical seating configuration, or up to 406 in sardine mode.  It is also the longest-range 787, capable of flying up to 14,140 km (7,635 nmi) nonstop with a typical passenger load, and the best-selling, with 406 delivered as of the end of 2018 and 384 more in the pipeline.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;787-10&lt;/em&gt; is the largest 787, able to sardine in up to 440 passengers if need be, although 330 is a more typical load.  The price it pays for this increase in capacity (achieved by stretching the already-stretched 787-9, this time by 5.5 meters [18 feet]) is a decrease in range, down to 11,910 km (6,430 nmi) one-way.  The 787-10 made its first flight at the end of March 2017, and carried its first paying passengers in April 2018 with Singapore Airlines.  15 have been delivered so far, and Boeing has orders for 154 more.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;787-3&lt;/em&gt;, a short-range (5,650-km [3,050-nmi]) variant designed especially for the Japanese market, was cancelled in December 2010, with its 43 orders (from Japan Airlines and All Nippon Airways) being converted to orders for 787-8s.  In order to fit into airport gates designed for smaller aircraft, it would have had shorter wings than the 787-8, and used &lt;a href=&quot;/questions/tagged/winglets&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;winglets&amp;#39;&quot; rel=&quot;tag&quot;&gt;winglets&lt;/a&gt; rather than the raked-back wingtips found on all other 787s.  Not needing to fly especially long distances, it would still have been able to carry 290 to 330 passengers in a typical seating arrangement (slightly more than the 787-9), although less efficiently than the longer-winged 787s.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The 787 mainly competes with the 767, &lt;a href=&quot;/questions/tagged/airbus-a330&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a330&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a330&lt;/a&gt; (and - to a much lesser extent - the &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;), and &lt;a href=&quot;/questions/tagged/airbus-a350&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a350&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a350&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See Wikipedia for more information about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 787&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Sonic_Cruiser&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 787’s spiritual predecessor&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems&quot; rel=&quot;nofollow noreferrer&quot;&gt;the 787’s batteries o’ fire&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-09-14T00:25:26.277" LastActivityDate="2019-09-14T00:25:26.277" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14155" PostTypeId="4" CreationDate="2015-04-17T02:33:58.803" Score="0" Body="A twin-engine widebody jetliner produced by Boeing since 2007, typically carrying between 242 and 440 passengers.  Notable for being the first Boeing jetliner to utilize composites for a large portion of its structure." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-03-19T03:21:59.223" LastActivityDate="2019-03-19T03:21:59.223" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14156" PostTypeId="5" CreationDate="2015-04-17T02:34:33.343" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:34:33.343" LastActivityDate="2015-04-17T02:34:33.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14157" PostTypeId="4" CreationDate="2015-04-17T02:34:33.343" Score="0" Body="The instrument which indicates the aircraft's altitude, usually based on atmospheric pressure, but sometimes on radar or GPS data instead." OwnerUserId="1696" LastEditorUserId="22726" LastEditDate="2019-02-12T14:07:46.437" LastActivityDate="2019-02-12T14:07:46.437" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14158" PostTypeId="5" CreationDate="2015-04-17T02:38:27.940" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:38:27.940" LastActivityDate="2015-04-17T02:38:27.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14159" PostTypeId="4" CreationDate="2015-04-17T02:38:27.940" Score="0" Body="Equipment which assists pilots in navigation, such as a VOR." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:38:27.940" LastActivityDate="2015-04-17T02:38:27.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14160" PostTypeId="5" CreationDate="2015-04-17T02:39:40.993" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:39:40.993" LastActivityDate="2015-04-17T02:39:40.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14161" PostTypeId="4" CreationDate="2015-04-17T02:39:40.993" Score="0" Body="Aircraft which maintain flight through buoyancy due to their volume weighing less than the surrounding air." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:39:40.993" LastActivityDate="2015-04-17T02:39:40.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14162" PostTypeId="5" CreationDate="2015-04-17T02:40:30.133" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:40:30.133" LastActivityDate="2015-04-17T02:40:30.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14163" PostTypeId="4" CreationDate="2015-04-17T02:40:30.133" Score="0" Body="A special pilot rating which allows them to operate a certain type of aircraft. Needed in addition to the applicable category of plot license." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:40:30.133" LastActivityDate="2015-04-17T02:40:30.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14164" PostTypeId="5" CreationDate="2015-04-17T02:41:36.950" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zKdrI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zKdrI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source:&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Airflow_in_auto-2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikimedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="19" LastEditDate="2016-07-04T16:19:33.523" LastActivityDate="2016-07-04T16:19:33.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14165" PostTypeId="4" CreationDate="2015-04-17T02:41:36.950" Score="0" Body="Mode of flight in a rotorcraft where the rotor is not powered by the engine. In helicopters this used in case of an engine failure and it allows for a controlled landing. It is also the working principle behind autogyro's. " OwnerUserId="1696" LastEditorUserId="19" LastEditDate="2016-07-04T16:19:33.523" LastActivityDate="2016-07-04T16:19:33.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14166" PostTypeId="5" CreationDate="2015-04-17T02:43:05.507" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:43:05.507" LastActivityDate="2015-04-17T02:43:05.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14167" PostTypeId="4" CreationDate="2015-04-17T02:43:05.507" Score="0" Body="Systems that aim to prevent ice from forming on the outer surface of an aircraft, especially the wings, engine intakes, windows, and propellers (as applicable)." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:43:05.507" LastActivityDate="2015-04-17T02:43:05.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14168" PostTypeId="5" CreationDate="2015-04-17T02:44:32.003" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:44:32.003" LastActivityDate="2015-04-17T02:44:32.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14169" PostTypeId="4" CreationDate="2015-04-17T02:44:32.003" Score="0" Body="The process of taking an engine that is shut down and getting it running again." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:44:32.003" LastActivityDate="2015-04-17T02:44:32.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14170" PostTypeId="5" CreationDate="2015-04-17T02:45:07.480" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:45:07.480" LastActivityDate="2015-04-17T02:45:07.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14171" PostTypeId="4" CreationDate="2015-04-17T02:45:07.480" Score="0" Body="Special seats typically used in fighter aircraft that can propel the crew clear of the aircraft in an emergency." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:45:07.480" LastActivityDate="2015-04-17T02:45:07.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14172" PostTypeId="5" CreationDate="2015-04-17T02:46:54.057" Score="0" Body="&lt;p&gt;An &lt;em&gt;airfoil&lt;/em&gt; is the two-dimensional cross-section of a wing or other aircraft surface.  It is generally shaped so that it provides lift to keep the aircraft in the air, but can also, or instead, be optimised to provide control, drag, or something else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different flight regimes have different optimal airfoil shapes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2018-06-28T05:43:27.290" LastActivityDate="2018-06-28T05:43:27.290" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14173" PostTypeId="4" CreationDate="2015-04-17T02:46:54.057" Score="0" Body="The 2D shape of a section of aircraft wing." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:46:54.057" LastActivityDate="2015-04-17T02:46:54.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14174" PostTypeId="5" CreationDate="2015-04-17T02:47:11.853" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:47:11.853" LastActivityDate="2015-04-17T02:47:11.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14175" PostTypeId="4" CreationDate="2015-04-17T02:47:11.853" Score="0" Body="Legal responsibility." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:47:11.853" LastActivityDate="2015-04-17T02:47:11.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14176" PostTypeId="5" CreationDate="2015-04-17T02:47:47.657" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:47:47.657" LastActivityDate="2015-04-17T02:47:47.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14177" PostTypeId="4" CreationDate="2015-04-17T02:47:47.657" Score="0" Body="Flight control similar to a joystick, which is used to control all fly-by-wire Airbus aircraft." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:47:47.657" LastActivityDate="2015-04-17T02:47:47.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14178" PostTypeId="5" CreationDate="2015-04-17T02:48:30.600" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:48:30.600" LastActivityDate="2015-04-17T02:48:30.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14179" PostTypeId="4" CreationDate="2015-04-17T02:48:30.600" Score="0" Body="An event in which a laser beam illuminates the cockpit of an aircraft. This can blind and disorient the pilots, creating a very dangerous situation." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:48:30.600" LastActivityDate="2015-04-17T02:48:30.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14180" PostTypeId="5" CreationDate="2015-04-17T02:50:32.843" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:50:32.843" LastActivityDate="2015-04-17T02:50:32.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14181" PostTypeId="4" CreationDate="2015-04-17T02:50:32.843" Score="0" Body="The 8th chemical element, which is essential for human life. Above a certain altitude, local air pressure is not sufficient for humans to receive enough oxygen to remain fully aware or conscious. Supplemental oxygen is needed if cabin pressure is not sufficient." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T02:50:32.843" LastActivityDate="2015-04-17T02:50:32.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14182" PostTypeId="2" ParentId="14114" CreationDate="2015-04-17T04:15:03.513" Score="4" Body="&lt;p&gt;Reading a lot is key; staying on top of your checklists too. I noticed I'm behind the airplane more depending on the complexity of the aircraft in question. I keep photocopies of my checklists at home to refresh my mind prior to a flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be mentioned the value of sitting in your aircraft on the ground; it costs nothing, and you can take your time working through checklists and scenarios in your mind.&lt;/p&gt;&#xA;" OwnerUserId="8168" LastEditorUserId="65" LastEditDate="2015-04-20T13:56:44.930" LastActivityDate="2015-04-20T13:56:44.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14183" PostTypeId="2" ParentId="8665" CreationDate="2015-04-17T04:33:25.977" Score="1" Body="&lt;p&gt;Excellent points. Simply put, the B52 is cost effective. Ghost Rider is an example. One of our B52's was damaged, so Ghost rider will be retrofitted (from mothballs), for $13M. The military's decision to upgrade electronics and weapons systems in all B52s shows their reliance (and confidence) in the aircraft. &lt;a href=&quot;http://www.dodbuzz.com/2013/07/12/air-force-begins-massive-b-52-overhaul/&quot; rel=&quot;nofollow&quot;&gt;http://www.dodbuzz.com/2013/07/12/air-force-begins-massive-b-52-overhaul/&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's impossible to cost justify replacing it (the tried) so BUFF keeps flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not stealthy, but don't underestimate its ability to jamb signals. Even using non-powered bombs, from its altitude, glide bombs can be released 60 miles from target. &lt;/p&gt;&#xA;" OwnerUserId="8167" LastActivityDate="2015-04-17T04:33:25.977" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14185" PostTypeId="2" ParentId="14111" CreationDate="2015-04-17T05:58:56.417" Score="6" Body="&lt;p&gt;&lt;strong&gt;Homing &amp;amp; 0° relative bearing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Homing is a technique used with ADF/NDB navigation, where you point the ADF needle at &lt;code&gt;0°&lt;/code&gt; relative bearing, which means that your nose is directly pointed at the navigational aid you are trying to reach. The same technique can crudely be used with VORs and GPS, where homing onto a VOR would be changing the inbound radial every few minutes to establish a new heading to the VOR or using GPS GOTO every few minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is considered a poor navigational technique, as it purposely neglects wind correction and this the aircraft can get blown off track significantly. You also increase the leg time with this, as you take longer to reach the navaid than with wind correction applied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ey7EB.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.navfltsm.addr.com/ndb-nav-adf-2.htm&quot; rel=&quot;noreferrer&quot;&gt;navfltsim&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;0°&lt;/code&gt; relative bearing refers to your longitudinal axis being in line with a navaid, mostly NDB. If something was straigh at your 3 o'clock, it would have a relative bearing of &lt;code&gt;90°&lt;/code&gt;, irrespective of your current magnetic heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tracking&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tracking is technically the same as Homing, however wind correction is applied. Simplified, you account for wind direction and speed and correct your magnetic heading by the wind correction factor, giving you a new corrected heading, which allows you to track to the navaid you are trying to reach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KiKQq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.avstop.com)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Hold, Hold pattern and Hold entry&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A hold or hold pattern is a racetrack defined by inbound course to a fix, a turn direction and turn time, usually given in minutes. A standard hold will usually be right turns with a timing of 4min for the racetrack, which is 1min for each &lt;code&gt;180°&lt;/code&gt; turn and 1min for each straight legs. Depending on from where you are trying to enter a hold, there will be different hold entry techniques.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DiwaE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.americanflyers.net)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-04-17T06:10:00.040" LastActivityDate="2015-04-17T06:10:00.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14187" PostTypeId="2" ParentId="14094" CreationDate="2015-04-17T08:09:01.767" Score="4" Body="&lt;p&gt;You want to check the &lt;strong&gt;Activities&lt;/strong&gt; box.&lt;/p&gt;&#xA;&lt;p&gt;The phrasing is a little weird, and it certainly doesn't line up with the regs (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.1.2.8.1.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §61.197&lt;/a&gt;), but that's what you want:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) Submitting a completed and signed application with the FAA and satisfactorily completing one of the following renewal requirements—&lt;/p&gt;&#xA;&lt;p&gt;(i) A record of training students showing that, during the preceding 24 calendar months, the flight instructor has endorsed at least 5 students for a practical test for a certificate or rating and at least 80 percent of those students passed that test on the first attempt.&lt;/p&gt;&#xA;&lt;p&gt;(ii) A record showing that, within the preceding 24 calendar months, the flight instructor has served as a company check pilot, chief flight instructor, company check airman, or flight instructor in a part 121 or part 135 operation, or in a position involving the regular evaluation of pilots.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, best as I can tell, that means:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;§61.197(2)(i)&lt;/strong&gt; is activity - 80% pass rate on 5+ students in the preceding 24 calendar months.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;§61.197(2)(ii)&lt;/strong&gt; is duties and responsibilities - serving in a position that involves standardization flights or stage checks.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;Disclaimer:&lt;/em&gt; unfortunately, all of the AOPA material on CFI renewal is designed to get you to buy their FIRC (eyeroll), and the unhelpful &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CCUQFjAB&amp;amp;url=https%3A%2F%2Fiacra.faa.gov%2Fiacra_manuals%2FIACRA_Instruction_Manual_Instructor.pdf&amp;amp;ei=0r8wVebfIc_hoASn7YG4Bw&amp;amp;usg=AFQjCNENzfRBcbl3pYhlmQBn2uCuAlpo7A&amp;amp;sig2=O0C5YSNsUvnH4Cbm2Sa-7g&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA IACRA document for instructors&lt;/a&gt; says squat as well. I'm having a hard time finding a reference that proves my interpretation, but I know it's correct!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-17T17:39:27.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14188" PostTypeId="1" AcceptedAnswerId="14214" CreationDate="2015-04-17T09:35:42.713" Score="2" ViewCount="1184" Body="&lt;p&gt;I'm researching the amount of solar energy available to photovoltaic cells placed at various locations on an aircraft's body. To calculate the angle of incidence of the sunlight on different parts of the plane I need a complete set of attitude angles of the aircraft (pitch, roll and yaw or equivalents) during flight. Can anyone tell me where to get this data?&lt;/p&gt;&#xA;" OwnerUserId="8172" LastActivityDate="2015-04-19T16:00:39.430" Title="Where can I download flight data containing pitch, roll and yaw angles?" Tags="&lt;attitude&gt;" AnswerCount="3" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="14189" PostTypeId="2" ParentId="14109" CreationDate="2015-04-17T13:06:39.150" Score="15" Body="&lt;p&gt;Because video is mostly useless for investigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The investigators need to know the exact flightpath, which is already recorded by the ATC radar and by the flight data recorder, they need to know whether and which systems failed, which is recorded by the flight data recorder, and they need to know what the pilots were doing, for which they have cockpit voice recorder and the radio communication is also recorded in the ATC facility (tower).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Video would be worse for determining the flight path than both ATC radar and FDR and while ATC radar does not have attitude, FDR does and again more precisely than video. Plus video &lt;em&gt;might&lt;/em&gt;, depending on angle, have &lt;em&gt;external&lt;/em&gt; damage, but that can generally be determined by examining the wreckage quite fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So video would add very little information over the existing recordings and thus it is not cost-effective to add it &lt;em&gt;for just this purpose&lt;/em&gt; at &lt;em&gt;all airports&lt;/em&gt; (it may be used if it is installed for security purposes).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="43" LastEditDate="2015-04-17T13:41:02.010" LastActivityDate="2015-04-17T13:41:02.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14190" PostTypeId="2" ParentId="14188" CreationDate="2015-04-17T13:10:33.363" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://blog.cykey.ca/post/88174516880/analyzing-flightradar24s-internal-api-structure&quot; rel=&quot;nofollow&quot;&gt;FlightRadar 24 has an API&lt;/a&gt; that you can get data from. This is only from aircraft with ADS-B transponders, so it excludes some smaller and older planes. This would indirectly:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Give you points with which you could calculate the turns.&lt;/li&gt;&#xA;&lt;li&gt;Give you pitch as the rate of climb.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This might give you a bigger but less exact dataset. Unfortunately, you might be disappointed in that normal commercial aircraft make relatively few manoeuvres at cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the sort of simulations you might find that making a simulated flight in &lt;a href=&quot;http://flightgear.org&quot; rel=&quot;nofollow&quot;&gt;FlightGear&lt;/a&gt; (Open Source Simulator) might yield better results. If memory serves me right there is some equivalent to a flight data recorder so you can pull the data when you are finished.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-04-17T20:39:19.973" LastActivityDate="2015-04-17T20:39:19.973" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14191" PostTypeId="5" CreationDate="2015-04-17T15:22:30.233" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:22:30.233" LastActivityDate="2015-04-17T15:22:30.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14192" PostTypeId="4" CreationDate="2015-04-17T15:22:30.233" Score="0" Body="The flow of air with respect to the ground. This will affect the performance and handling of aircraft and can be a limiting factor." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:22:30.233" LastActivityDate="2015-04-17T15:22:30.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14193" PostTypeId="5" CreationDate="2015-04-17T15:23:57.947" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:23:57.947" LastActivityDate="2015-04-17T15:23:57.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14194" PostTypeId="4" CreationDate="2015-04-17T15:23:57.947" Score="0" Body="A page reachable by Internet browser. For questions here, it should contain some type of aviation-related information." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:23:57.947" LastActivityDate="2015-04-17T15:23:57.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14195" PostTypeId="5" CreationDate="2015-04-17T15:33:25.233" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:33:25.233" LastActivityDate="2015-04-17T15:33:25.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14196" PostTypeId="4" CreationDate="2015-04-17T15:33:25.233" Score="0" Body="A device made of thin material designed to unfold and create drag, typically used to arrest the descent of a falling object." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:33:25.233" LastActivityDate="2015-04-17T15:33:25.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14197" PostTypeId="5" CreationDate="2015-04-17T15:34:21.343" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:34:21.343" LastActivityDate="2015-04-17T15:34:21.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14198" PostTypeId="4" CreationDate="2015-04-17T15:34:21.343" Score="0" Body="ICAO does not create enforceable regulations, but releases recommendations for regulations that member nations should enact." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:34:21.343" LastActivityDate="2015-04-17T15:34:21.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14199" PostTypeId="5" CreationDate="2015-04-17T15:37:10.893" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:37:10.893" LastActivityDate="2015-04-17T15:37:10.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14200" PostTypeId="4" CreationDate="2015-04-17T15:37:10.893" Score="0" Body="The maximum distance at which something is effective. This can relate to when an aircraft will run out of fuel, or when an electronic transmission will be too weak to receive." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:37:10.893" LastActivityDate="2015-04-17T15:37:10.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14201" PostTypeId="5" CreationDate="2015-04-17T15:47:15.997" Score="0" Body="&lt;p&gt;ICAO defines visibility as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a) the greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when&#xA;  observed against a bright background;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) the greatest distance at which lights of 1,000 candelas can be seen and identified against an unlit background.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note.— The two distances have different values in air of a given extinction coefficient, and the latter b) varies with the background&#xA;  illumination. The former a) is represented by the meteorological&#xA;  optical range (MOR).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:47:15.997" LastActivityDate="2015-04-17T15:47:15.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14202" PostTypeId="4" CreationDate="2015-04-17T15:47:15.997" Score="0" Body="The maximum distance at which objects can be seen." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:47:15.997" LastActivityDate="2015-04-17T15:47:15.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14203" PostTypeId="5" CreationDate="2015-04-17T15:48:31.913" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:48:31.913" LastActivityDate="2015-04-17T15:48:31.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14204" PostTypeId="4" CreationDate="2015-04-17T15:48:31.913" Score="0" Body="A state in which one or more systems on an aircraft have failed, affecting the aircraft as a whole." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:48:31.913" LastActivityDate="2015-04-17T15:48:31.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14205" PostTypeId="5" CreationDate="2015-04-17T15:48:59.593" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:48:59.593" LastActivityDate="2015-04-17T15:48:59.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14206" PostTypeId="4" CreationDate="2015-04-17T15:48:59.593" Score="0" Body="Use for descents in general, else use [approach] or [landing]." OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2020-03-10T09:53:29.937" LastActivityDate="2020-03-10T09:53:29.937" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14207" PostTypeId="5" CreationDate="2015-04-17T15:51:16.920" Score="0" Body="" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:51:16.920" LastActivityDate="2015-04-17T15:51:16.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14208" PostTypeId="4" CreationDate="2015-04-17T15:51:16.920" Score="0" Body="Instances where an aircraft is coming in to land and the pilot is able to see landmarks and the runway in order to navigate the landing." OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-17T15:51:16.920" LastActivityDate="2015-04-17T15:51:16.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14209" PostTypeId="1" AcceptedAnswerId="14211" CreationDate="2015-04-17T17:05:24.223" Score="3" ViewCount="636" Body="&lt;p&gt;For example, ailerons allow air to flow past both the top and bottom surfaces, which makes it more aerodynamic than speedbrakes. Also, plane rudders have air flowing on both sides, which is apparently mote efficient than a spoiler. Why does this happen?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastActivityDate="2015-05-22T16:38:03.347" Title="Why is a control surface that allows two sides of airflow better than those that allow one?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14210" PostTypeId="2" ParentId="14209" CreationDate="2015-04-17T17:17:05.880" Score="1" Body="&lt;p&gt;The main answer is drag. A spoiler will create more drag than a surface that allows flow over both sides. In the case of speed brakes this is what you want to happen as you want to slow the plane down. With control surfaces you want to alter airflow with out creating excess drag. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="923" LastEditDate="2015-04-17T17:28:52.510" LastActivityDate="2015-04-17T17:28:52.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14211" PostTypeId="2" ParentId="14209" CreationDate="2015-04-17T18:07:11.237" Score="4" Body="&lt;p&gt;For low drag, you want to minimize the surface changes presented to the air flow. Large changes in the surface will create turbulence and pressure changes that contribute to drag. Small changes will minimize these sources of drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you move a control surface like an aileron or elevator, air is flowing past both sides of the airfoil. Although this changes the direction of the flow, which gives the control force as well as some drag, the air can still flow past both sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a spoiler, the air cannot flow past both sides. This increases the frontal area presented to the flow, and creates a low pressure area behind the deployed surface. Creating a low-pressure area behind an object is a big contributor to drag, which is why &lt;a href=&quot;http://exploration.grc.nasa.gov/education/rocket/shaped.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;aerodynamic bodies tend to have a teardrop shape&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilers on the wing also have the effect of reducing lift. By disrupting the smooth low-pressure flow over the upper surface of the wing, they reduce the effectiveness of the wing, effectively &lt;a href=&quot;https://aviation.stackexchange.com/q/6366/1696&quot;&gt;stalling the affected portion&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an illustration of both principles in action, &lt;a href=&quot;https://www.youtube.com/watch?v=ysb5QIHcLSQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;see this video&lt;/a&gt; of a speed brake on a Mooney. This shows how even a relatively small object, when disrupting the air flow, can add a significant amount of drag.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-04-17T18:07:11.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14213" PostTypeId="2" ParentId="14209" CreationDate="2015-04-17T20:45:01.197" Score="2" Body="&lt;p&gt;The reason is that both sides of a control surface experience pressure  changes, both ahead and aft of the hinge line. In case of spoilers and speed brakes, only one side is affected, so the effectiveness is only half as big.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please see the pressure coefficient plots of an airfoil for three different flap deflections below. Upper and lower surface pressure are shown by color-coded lines, and lower lines belong to the lower surface. Dashed lines show the inviscid pressure, and solid lines the pressure distribution with friction effects added. The wider two lines of the same color are apart, the more lift is created. Note the contour plot below, which follows the color scheme of the pressure plots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p4Z2X.png&quot; alt=&quot;E502 with three flap angles&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While control surfaces normally are deflected by less than ±20°, regular spoilers are extended by 60° or more to create as much drag as possible. But even if they are extended by similar angles to those of a control surface, the air will have no chance to flow orderly along the leeward side. Instead, this side will only have separated, chaotic airflow, while the windward side will show a flow pattern very similar to the windward side of a control surface. The pressure in separated flow will not change with deflection angle, so this side will not contribute any lift effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note in the picture above that the pressure level over the whole chord is pushed up or down by the flap, because the flap is located in the aft portion of the airfoil. In contrast to that, spoilers are mounted mid-chord, where their influence over the pressure level is smaller. This reduces the lift effects of spoilers even more.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-04-17T20:45:01.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14214" PostTypeId="2" ParentId="14188" CreationDate="2015-04-17T22:09:06.777" Score="4" Body="&lt;p&gt;To answer the question as asked, such data is out there, although it may be hard to get.  A flight simulator program is probably much easier, although the real answer to the question probably is, the effects of anything other than straight &amp;amp; level flight are probably dwarfed by the effects of DIRECTION of flight coupled with time-of-day (i.e. is the sun overhead, or low on the horizon to one side or the other, or ahead of or behind the aircraft), and the effect of cloud cover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines capture exactly the data being discussed as part of the Flight Data Recorder -- one of the two famous &quot;black box&quot; recorders (the other being the Cockpit Voice Recorder).  This data is routinely downloaded by the airlines' maintenance departments and analyzed as part of Flight Operations Quality Assurance or FOQA programs.  They can see roll, pitch, yaw, heading, altitude, position, track, and dozens if not hundreds of other parameters, all on a moment-by-moment basis, and the analysis of this data is used to inform any number of proactive safety efforts.  Rather than waiting for an accident, they can see where things are starting to drift away from what's desired, and take preventative actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem here is that FOQA data is extremely sensitive, and for an outsider to get access to it is probably somewhere between extremely difficult, and absolutely impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next step down from that would be the logged data as has been discussed in the various comments, and I'm not smart enough on those specifics to add anything useful to what's already been posted as far as where and how to get those logs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After that, it is possible to record data yourself, with the right equipment (not cheap).  Using an iPad with Foreflight and an AHRS unit (essentially a self-contained INS, with receivers for things like XM satellite weather, GPS, and ADSB, you can record a track log that includes all the parameters mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the issue: if you're paying for that equipment and the flight time, you will want to get &lt;strong&gt;&lt;em&gt;DATA&lt;/em&gt;&lt;/strong&gt; for your efforts... so let's go do &lt;strong&gt;&lt;em&gt;STUFF&lt;/em&gt;&lt;/strong&gt; so we have an interesting track log: do some holding, fly a few approaches, maybe a steep turn or a stall series.  Because that's much more interesting &lt;strong&gt;&lt;em&gt;DATA&lt;/em&gt;&lt;/strong&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the simple fact is that when airplanes are actually being used for anything besides flight training, most of what they're doing is simple boring straight &amp;amp; level flight, probably on autopilot.  Most of the maneuvering happens at the beginning &amp;amp; end of the flight, on the departure and then on the arrival and the approach, and that all happens at lower altitudes where clouds will have the greatest influence how much sun your solar collectors are getting.  Up in the 30-to-40-thousand feet range is where most of the cruise flight happens, mostly straight and level, and with most (though not all) of the sun-blocking clouds below you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a realistic estimate of how much solar energy your panels can get, I strongly suspect that you'll do best with an assumption of straight &amp;amp; level flight, and models of the various possibilities of direction of flight and time-of-day.  And combine that with estimates of how cloud cover will affect your ability to collect solar energy (remembering that plenty of flights happen at night).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A really accurate log of a &lt;em&gt;particular&lt;/em&gt; flight could allow you to calculate to fairly high precision how your received energy would vary over time &lt;em&gt;for that exact flight&lt;/em&gt;, but when you want to generalize that out to a large number of operations, you'll need to look at the factors that influence collection the most, and those will be the variables &lt;em&gt;other than&lt;/em&gt; detailed records of roll &amp;amp; pitch.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-17T22:09:06.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14218" PostTypeId="2" ParentId="14209" CreationDate="2015-04-18T07:19:56.763" Score="0" Body="&lt;p&gt;I think you question comes to the difference between aerodynamic body and blunt body. It is no so much linked to exposing one or two surfaces to the external flow, but more linked to the shape exposed to the external flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aerodynamic body has a shape which produces low drag, aerodynamic bodies have a very small size normal to the direction of flight. For example, the wing is really thin in the vertical direction, but huge is the direction the plane is expected to flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A blunt body is the oppossite way around, exposes a big surface in front of the moving direction. The spoilers are a very good example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can give you a practical example, you hand. When you are in your car (in movement) and you extend your hand outside the car, having the hand parallel to the ground, you don't notice significant &quot;pressure&quot; or &quot;force&quot; over your hand (please use some nice speed...) however is you set your palm looking to the direction the car is moving, the &quot;pressure&quot; over you hand is much bigger as you are exposing a bigger surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example the same phenomena with your hand is happening with ailerons, rudders and airbrake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We use an airbrake to stop the airplane, that is why we use like your palm in the car. Stop the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ailerons and rudders are intended to not stop the airplane, but control it. That's why the intention is to have low drag.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-04-18T07:19:56.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14221" PostTypeId="1" CreationDate="2015-04-18T23:42:15.753" Score="11" ViewCount="5104" Body="&lt;p&gt;When I retire in a couple years I want to fly my 172 and make some money. Even if I just break even that's ok.  My CFI certificate has expired and I don't want the hassle of having it re-instated. I do have a commercial pilot license. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would it take to give &quot;scenic airplane rides&quot; legally (so I have insurance). I read far 91.147 but it says nothing about the airplane itself.&lt;/p&gt;&#xA;" OwnerUserId="8183" LastEditorUserId="69" LastEditDate="2015-04-20T21:31:20.960" LastActivityDate="2016-02-20T16:50:57.083" Title="What are the aircraft requirements to legally offer commercial sightseeing flights in a C-172?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14223" PostTypeId="1" AcceptedAnswerId="14301" CreationDate="2015-04-19T03:11:36.387" Score="10" ViewCount="5063" Body="&lt;p&gt;I was up flying today – VFR – and the attitude indicator tumbled. It's a 6-year-old RC Allen 22-7, without the ability to cage, so I just wound up letting it be all off-kilter until things stabilized... which took almost an hour. The vacuum was in the green the entire flight, and at no point was I doing any wild maneuvering. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anything I could have done to accelerate the process? Could I have caused damage by not landing and shutting down?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-04-21T21:48:40.817" LastActivityDate="2017-06-13T13:51:13.817" Title="How does one reset an attitude indicator that doesn't have a cage?" Tags="&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14225" PostTypeId="1" CreationDate="2015-04-19T03:46:55.073" Score="17" ViewCount="2226" Body="&lt;p&gt;About 6 months ago in a hangar at a local (KLWT), I saw a &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_PA-30_Twin_Comanche&quot;&gt;Piper PA-30 Twin Comanche&lt;/a&gt; and instantly wanted it. When I got home, I did a look up on the Registration (N) number and found out that the aircraft was de-registered in 2005.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did some asking around the airport the next day and discovered that the owner had passed away. After some more research, I discovered that the airplane had one engine and its prop totaled. It had the propeller and engine replaced, but neither had logbooks and that was why the plane is collecting dust.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I really would like the airplane, because it is actually in good condition, yet it sits in the back of the central hangar and is ignored by everyone. So in a nutshell, the airplane is in good condition with airframe, avionics and logbooks for the right engine and prop. There are just no left prop or engine books.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current owners (the estate of the deceased pilot) do not seem to even realize that the airplane is still sitting there, so I do not think that they would put much thought into selling the plane and I might be able to pick it up relatively cheaply. The only thing that I seem to need is a logbook. So I was wondering if it would be possible to somehow just start a new log after purchase? The other option is to just buy a new engine with books. Any advice?&lt;/p&gt;&#xA;" OwnerUserId="8185" LastEditorUserId="1467" LastEditDate="2015-07-23T16:46:33.667" LastActivityDate="2015-12-21T21:13:59.053" Title="How might one start a new logbook for an engine that had one lost?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14227" PostTypeId="2" ParentId="14109" CreationDate="2015-04-19T03:56:30.687" Score="8" Body="&lt;p&gt;As an airport manager, I often don't have the money to place cameras everywhere. Videos at the airport are an airport sponsor's responsibility, and most airport operators have very limited budgets. When you get into the larger airports, the cost is still an issue because of the amount of acreage that has to be covered. The other issue, is that Part 139 prohibits certain items  from being in the runway safety area, and a camera is not generally considered frangible. Even if I could put a camera by the runway, the best that I could do is a wildlife camera with at most a 70' visual distance with a heavily pixelated image.&lt;/p&gt;&#xA;" OwnerUserId="8186" LastActivityDate="2015-04-19T03:56:30.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14229" PostTypeId="2" ParentId="14225" CreationDate="2015-04-19T11:11:48.363" Score="12" Body="&lt;p&gt;One way to get a new engine logbook is to send the engine for a factory overhaul. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your engine will be regarded as a usable core, and will come back with all tolerances within &quot;as new&quot; limits and a new logbook.&lt;/p&gt;&#xA;" OwnerUserId="7892" LastActivityDate="2015-04-19T11:11:48.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14230" PostTypeId="1" AcceptedAnswerId="14233" CreationDate="2015-04-19T11:15:11.773" Score="6" ViewCount="778" Body="&lt;p&gt;I've just been watching a video of a 757 suffering a bird strike on take off. The pilots continue with their take off, declare a MAYDAY, shut the engine down and proceed to land without any issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Link to the video: &lt;a href=&quot;https://www.youtube.com/watch?v=9KhZwsYtNDE&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=9KhZwsYtNDE&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these engine reused after an event like this? Are they sent away to Rolls Royce, Pratt &amp;amp; Whitney etc to be repaired? Or are they always deemed a complete write off and replaced with new?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously turbine engines are highly balanced complex pieces of machinery so I can imagine once FOD has damaged this balancing the damage is pretty high.&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="19" LastEditDate="2016-12-05T11:35:59.630" LastActivityDate="2018-11-29T15:28:54.993" Title="Are turbine engine reconditioned after severe FOD damage caused by bird strikes?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14231" PostTypeId="2" ParentId="14108" CreationDate="2015-04-19T13:27:02.350" Score="9" Body="&lt;p&gt;Pressurized oxygen tanks have two big minus points: they are heavy, and they are essentially a small bomb. But they have two big plus points: they can be refilled easily and they don't generate any heat when you use them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chemical oxygen generator plus points are they are lightweight, self-contained and more-or-less maintenance-free (they don't leak). Minus points are they are single-use, time-limited and cannot be shut off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As nearly everything in aviation is a balance of good and bad, we often see both systems being used at the same time. The flight crew will use oxygen on a regular basis - sometimes procedurally, sometimes just to clear up a headache. They need to be able to turn it on and off, and the airline doesn't want to replace the system each time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers rarely need oxygen, and when they do it's only until the plane descends to breathable altitudes (which will happen really quickly).&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-04-19T13:27:02.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14232" PostTypeId="2" ParentId="14225" CreationDate="2015-04-19T14:44:05.303" Score="9" Body="&lt;p&gt;For an engine or prop, you can simply start a new log with the appropriate explanation as the first entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bonus, there's a good chance the airframe log will have the installation date and time so you might come up with TSMOH too (if not total time). If you can determine TSMOH, there is probably little value reduction due to the missing log assuming you can determine the engine/prop is airworthy. (it's a missing airframe log that really devalues an aircraft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But alas there is airworthiness (the strict FAA meaning of airworthiness) of the engine or prop. You want to know that it meets its type design or properly altered configuration and that it is in a safe condition to operate. So AD compliance does come into question here. If the aircraft went through an annual inspection since the engine/prop replacement, and was declared airworthy, although it is possible that the AD status went with the missing logs, it probably didn't. Typically most shops print out a status report for the aircraft including airframe, engines, props, &amp;amp; appliances and staple the whole report together and place it in the logbook pouch. This happens more often than not so if it's there you're good as long as the inspector signed that any applicable AD was properly dealt with... even  the &quot;Previously Complied With&quot; ones. That list then becomes the complying record.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most shops use some sort of computerized aid for AD status. Usually they save the aircraft profile and report in memory so they have less work next year. If your lucky, maybe they can reprint and resign the list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airframe logbook has an entry for installing the engine maybe there is a hint of where the engine was overhauled. If so, that overhaul agency should be able to pull up a work order and if your lucky, give you more info like total time and what ADs were complied with at that point, etc.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="340" LastEditDate="2015-04-19T15:46:14.220" LastActivityDate="2015-04-19T15:46:14.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14233" PostTypeId="2" ParentId="14230" CreationDate="2015-04-19T15:37:19.133" Score="7" Body="&lt;p&gt;The damage is assessed and then a determination is made whether or not its economical to repair the engine.  It will truly be taken on a case by case basis.  However, FOD damage to the engine doesn't automatically mean the engine will be scrapped, and I think you'd be surprised with the damage they can suffer and still remain in service after repair.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2016-12-10T10:20:21.900" LastActivityDate="2016-12-10T10:20:21.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14234" PostTypeId="2" ParentId="14188" CreationDate="2015-04-19T16:00:39.430" Score="1" Body="&lt;p&gt;Assuming that you are asking this question to come to an optimum design point and conclude on the likelihood of different attitudes that can be seen by an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Yaw angle (heading) is the simplest part: as aircraft fly all around the world, you can take all possible heading angles into account. (Reasoning: aircraft fly to all directions possible. If you need to go into statistics of the subject, you can multiply the number of flights for each of the aviation hiways.)&lt;/li&gt;&#xA;&lt;li&gt;For Pitch angle, you can assume that during climbout, depending on the aircraft specifications, there will be an angle from a few degrees to ten plus degrees (larger climb rates involve military aircraft). And during descent, a negative angle of similar amount would take place. During cruise, pitch angle is close to zero: might change zero point some degrees as fuel is burnt and when the aircraft gets lighter. Therefore, a pitch angle of zero should be the optimum design point for any solar-harnessing system on an aircraft. Please keep in mind that the aircraft body (fuselage, wings and tails) surfaces have local surface normals.&lt;/li&gt;&#xA;&lt;li&gt;For Roll angle, unless you are looking for a loitering platform (where the aircraft turns around a location for long periods of time), the roll angle will be very close to zero for the straight legs of the flight. Turns will occasionally occur with bank angles of 20 to 30 degrees (again, depending on the radius of the turn, and the flight characteristics of the aircraft). Turns take up such a small fraction of the flight time that they can easily be ignored.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I'd like to also refer back to your main question, of where to find flight data. In case you really need it, there are online flight simulators, and their servers may have pre-recorded data. Otherwise, plugging into a server and recording the live data of flying aircraft could be considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time and location of the aircraft is one other important factor for determining the sun's angle relative to the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For time, you can assume any time of the day and year. &lt;/li&gt;&#xA;&lt;li&gt;And for location, only the poles are not covered (there are meteorological stations up to 72degrees North,and 52 degrees south). Existing flight routes (please see &quot;enroute charts&quot;) can be utilized to have a better understanding of where aircraft flights take place.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note that, military and commercial flight data (attitude) is generally considered confidential and proprietary.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-04-19T16:00:39.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14236" PostTypeId="1" CreationDate="2015-04-19T19:02:29.263" Score="7" ViewCount="3938" Body="&lt;p&gt;So lets consider that the stall angle (=Cl max) of a B747 is at 16° (in clean configuration). Does this mean, that, at whatever speed you are flying (i.e. 500 knots), you would stall if you go on a climb angle of more than 16°? So there is no need to always reduce the speed to the stall speed (which might lie at around 150 knots...).&#xA;I am just wondering, since, if you fly in the microsoft flight simulator with a big jet, you can have an angle of attack of 30° and more, and not stall until you get to the stall speed.&lt;/p&gt;&#xA;" OwnerUserId="8191" LastActivityDate="2015-04-21T22:45:36.830" Title="Is there always a stall if you exceed a specific angle of attack?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14237" PostTypeId="1" AcceptedAnswerId="14238" CreationDate="2015-04-19T19:07:55.537" Score="15" ViewCount="2974" Body="&lt;p&gt;This question applies to aircraft being tested, presumably within a certification program. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen what looks like either a ball or &quot;shuttlecock&quot; at the end of a tether attached to the top/rear extremity of an aircraft's vertical fin. An example can be seen toward the end of &lt;a href=&quot;https://www.youtube.com/watch?v=8JMN0qgG7q8&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is its purpose? Is is part of or does it contain any instrumentation, or is it there to provide direct visual indication of something - such as trailing airflow patterns?&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-04-19T20:30:21.780" Title="What is the purpose of the ball and string attached to the tip of the vertical fin on test aircraft?" Tags="&lt;flight-testing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14238" PostTypeId="2" ParentId="14237" CreationDate="2015-04-19T19:42:35.610" Score="12" Body="&lt;p&gt;That is a static pressure line. The &quot;shuttlecock&quot; device on the end pulls the line out behind the aircraft, where it can get a more accurate pressure reading, away from the air flowing around the aircraft that affects the regular &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot-static_system&quot; rel=&quot;noreferrer&quot;&gt;pitot-static system&lt;/a&gt;. It will also be more accurate during flight conditions that normal aircraft rarely experience, but need to be accurately analyzed during testing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YE1GJ.jpg&quot; alt=&quot;Static pressure thingy&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://commons.wikimedia.org/wiki/File:B787_prototype_tail_and_static_probe_%285998088979%29.jpg&quot; rel=&quot;noreferrer&quot;&gt;Cropped from this image&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static pressure has an effect on the performance of the aircraft, so during testing that is one value they want to measure accurately during flights. Once testing is complete there is no longer a need for that information, and the regular pitot-static system takes the measurements needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The line can be seen in &lt;a href=&quot;http://theaviationist.com/wp-content/uploads/2009/12/787-primo-volo_3.jpg&quot; rel=&quot;noreferrer&quot;&gt;this photo&lt;/a&gt;, and in &lt;a href=&quot;https://youtu.be/VkPVsToMG3s?t=1m49s&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;, you can see the reel inside the rear of the aircraft that is used to pull in the line when it is not in use.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-04-19T20:30:21.780" LastActivityDate="2015-04-19T20:30:21.780" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14239" PostTypeId="2" ParentId="14110" CreationDate="2015-04-19T20:23:56.583" Score="3" Body="&lt;p&gt;In the US there is a simple rhyme memory trick that you can use to figure out what altitudes would be valid for you to fly both VFR and IFR.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EAST IS LEAST - WEST IS BEST&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What that means is that you fly odd number altitudes when flying East (Magnetic) and even number altitudes when flying in a magnetic Westbound direction.  For VFR just add 500 ft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So valid West bound flights would be:  4000,6000,8000 IFR :  4500,6500,6500 VFR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same with East Bound:  5000,7000,9000 IFR : 5500,7500,9500 VFR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple rhyme that works pretty well for me.   Also BTW, if you are filing then chose the initial leg as your filing altitude.  If you are under ATC control, you'll see that ATC will eventually ask you to climb or descend if your course leg changes your direction.   IF VFR, and you make a bend that takes you to the other side, then climb or descend even if you are not talking to ATC.  If talking to ATC, let them know.  They can either tell you to stay put or pilots discretion to the new altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this is that head on's are pretty hard to do if everyone is flying the same direction.   You might get chewed up in the tail, but that's the job of the pilot in the plane overtaking you or ATC. &lt;/p&gt;&#xA;" OwnerUserId="8193" LastActivityDate="2015-04-19T20:23:56.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14241" PostTypeId="1" CreationDate="2015-04-19T20:41:59.337" Score="8" ViewCount="1360" Body="&lt;p&gt;I have not seen any additives (such as those used in automobiles) to clean and maintain fuel injectors in aviation engines.   Is there a reason for that such as the use of lead in 100LL or something else?   The fuel injectors will eventually constrict or clog as the avgas leaves residual deposits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some technical reason or is it just that no one has gone through the certification process or at least (like AVBlend or CamGuard) received the &quot;will do no harm&quot; approval from the FAA?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Removing, cleaning, reinstalling fuel injectors is not only expensive but you also risk damaging them and if you have the GAMI injectors you can have quite a bill coming at you.&lt;/p&gt;&#xA;" OwnerUserId="8193" LastEditorUserId="4474" LastEditDate="2015-04-19T21:59:54.323" LastActivityDate="2017-04-03T12:44:44.130" Title="Is there a fuel injector cleaner additive available?" Tags="&lt;fuel&gt;&lt;avgas&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14242" PostTypeId="2" ParentId="14236" CreationDate="2015-04-19T21:38:08.787" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there always a stall if you exceed a specific angle of attack?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, stall depends only on angle of attack. However&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does this mean, that, at whatever speed you are flying (i.e. 500 knots), you would stall if you go on a climb angle of more than 16°?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;. Climb angle and angle of attack are completely different things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.av8n.com/how/htm/aoa.html#sec-incidence&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://www.av8n.com/how/img48/incidence.png&quot; alt=&quot;pitch, angle of climb and angle of attack&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image from &lt;a href=&quot;https://www.av8n.com/how/htm/aoa.html#sec-incidence&quot; rel=&quot;nofollow noreferrer&quot;&gt;How It Flies&lt;/a&gt; shows the four different angles involved. &lt;em&gt;Pitch&lt;/em&gt; is the angle between aircraft floor and horizontal, wing &lt;em&gt;incidence&lt;/em&gt; is angle between aircraft floor and wing¹, angle of &lt;em&gt;climb&lt;/em&gt; is angle between &lt;em&gt;direction of flight&lt;/em&gt; (a.k.a “flight path” or “relative wind”) and horizontal and finally angle of &lt;em&gt;attack&lt;/em&gt; is angle between &lt;em&gt;direction of flight&lt;/em&gt; and wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image shows that angle of attack + angle of climb = pitch + wing incidence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Up to stall, lift depends approximately linearly on angle of attack and square of speed (and on air density). In straight flight the forces on the aircraft need to be balanced, so angle of attack will be such that they are. If you increase pitch, the angle of attack will increase, which will cause unbalanced force, which will cause upward acceleration and that will increase the climb angle at the expense of the angle of attack again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you go on a climb more than 16°, the angle of attack will not significantly differ from what it is when you fly level at the same speed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I am just wondering, since, if you fly in the microsoft flight simulator with a big jet, you can have an angle of attack of 30° and more, and not stall until you get to the stall speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No, you can't.&lt;/strong&gt; You, however, can climb at 30° or more, for a while before you run out of speed. Which at low altitude is actually quite long; the jet engines are designed to have enough power at high altitudes where air is much thinner and to allow taking off when one engine fails late in the take-off roll. Therefore low with all engines operating at full power you have quite a bit of extra thrust available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note, that stall does &lt;em&gt;not&lt;/em&gt; mean loss of &lt;em&gt;all&lt;/em&gt; lift. You only loose part of it. A significant part, but not all. Stalled aircraft is still controllable (though ailerons effect is reversed) and some aircraft (though this would be fighters, not airliners like 747) may even have enough lift and thrust to maintain altitude when stalled.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Specifically, the zero-lift line of the wing. This coincides with the chord of symmetric wings, but cambered wings have it tilted up.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.353" LastActivityDate="2015-04-20T04:42:41.647" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14243" PostTypeId="1" CreationDate="2015-04-19T22:26:13.793" Score="9" ViewCount="2894" Body="&lt;p&gt;How are landing minimums decided for a flight? Does the captain make the decision depending on weather conditions or is it preset for each airport?&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="3170" LastEditDate="2015-04-19T22:44:21.480" LastActivityDate="2015-04-20T14:38:30.320" Title="How are landing minimums decided?" Tags="&lt;landing&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14244" PostTypeId="2" ParentId="14243" CreationDate="2015-04-19T22:40:49.943" Score="6" Body="&lt;p&gt;It is different and set at every airport, at each runway, for each category (size) of plane, and for each procedure that is followed.  For example a VOR approach has higher minimums than a Localizer and then again than an ILS because of the precision of the approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general almost every approach to any IFR runway has different minimums including if it's a straight in (lower) or a circle to land (higher).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also planes with radar ground sensing that can fly what are called CAT III approaches and can land in almost zero-zero weather.  Those are highly automated and computer controlled landing systems. &lt;/p&gt;&#xA;" OwnerUserId="8193" LastEditorUserId="3504" LastEditDate="2015-04-20T14:38:30.320" LastActivityDate="2015-04-20T14:38:30.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14245" PostTypeId="2" ParentId="1262" CreationDate="2015-04-19T22:56:13.923" Score="1" Body="&lt;p&gt;It also depends if you have a low or high wing airplane.  And if you are comfortable touching down on one wheel.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my plane, A Socata TB, the plane has a monstrous rudder that has a demonstrated crosswind component of 25 knots.  That's demonstrated, I'll tell you it has the authority to do more but the manufacturer always errs on the side of safety.  It also is a low wing, so high crosswind landings get be nervous that I might scrape a wing edge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me being sideways is not normal.  Crabbing to the runway means that you are heading at the runway but it may not be at your nose.  But it is holding a steady view relative to a point on your windscreen.  Remember, the training if you see another plane.  If it's moving relative to a point on your windshield that's good.  If it's not and maintaining the same point, you are generally on a collision course.  Same with the runway numbers, if they are off to your left and the runway is coming at you, you might be pointing at the control tower but your &quot;Ground Path&quot; is straight down the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll crab all the way down, then bleed off energy using the T-6 P-51 training I received, then just as I feel the final drop beginning, I'll add about 2 inches of MP to arrest the decent and kick out to point the nose down the runway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the only time your wheels have to be straight down the runway is 1 millisecond before the rubber hits the road!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also in retrospect, I assume the turn Crabbing is derived from the way a real Crab moves.  It walks sideways to go forward. &lt;/p&gt;&#xA;" OwnerUserId="8193" LastEditorUserId="8193" LastEditDate="2015-04-19T23:02:26.033" LastActivityDate="2015-04-19T23:02:26.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14246" PostTypeId="1" AcceptedAnswerId="14270" CreationDate="2015-04-19T23:07:02.550" Score="11" ViewCount="810" Body="&lt;p&gt;I just watched the Mayday episode &lt;em&gt;Cleared for Disaster,&lt;/em&gt; a dramatization of &lt;a href=&quot;https://en.wikipedia.org/wiki/USAir_Flight_1493&quot;&gt;USAir Flight 1493&lt;/a&gt;. The episode covered how the controller lost situational awareness and gave a landing clearance to 1493 while SkyWest 5569 was still on the runway, as well as how the runway lights obscured 5569's lights. They did not, however, talk much about 5569. This was at least partly because 5569 was not carrying a CVR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower would have given 1493 the clearance to land on runway 24L on the same frequency that 5569 should have been on. In other words, 5569 would have been sitting on 24L and hearing tower give landing clearance for 24L, which would be a big red flag. Are they expected to be listening and thinking about landing clearances given to other aircraft? If they noticed, would they be expected to speak up, or to shut up and trust the controller?&lt;/p&gt;&#xA;" OwnerUserId="3170" LastEditorUserId="3170" LastEditDate="2015-04-19T23:27:10.687" LastActivityDate="2016-12-02T02:59:08.787" Title="Are pilots expected to keep an ear out for conflicting authorizations?" Tags="&lt;accidents&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14247" PostTypeId="2" ParentId="14246" CreationDate="2015-04-19T23:48:31.717" Score="-3" Body="&lt;p&gt;Short answer, never trust the controller.  If the worst happens all the controller will have is paperwork to do and lots of meetings.  But your family will have your funeral to tend to.  As PIC you are the sole authority as to the safety of your flight.  As for listening, IMHO, it's more important to listen carefully at takeoff and landings.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We train ourselves, while in the air to listen for the 1st word which is the call-sign of the aircraft and if it's ours then it has our attention and if there are other passengers on my plane my hand goes up for them to keep quiet.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But during landing, approaches, etc, we must familiarize ourselves not with just the approach or runway we are landing on but we should know the configuration of the airport in general.  In single runway airports, it's not as hard.  You just have to know which runway is landing and taking off and if you hear other wise then you speak up.    In multiple runway airports, especially with low visibility if you are still high enough, do not be afraid to key up and ask a question.  Just as you would key up even without a call-sign and ask 'Wind Check'.   The controllers then broadcast the current winds in the blind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you are on short final and are still unsure, there is only one thing that is the safest. Abort the landing, and do a go-around as you are informing the tower you are going around because of unclear instructions.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they give you a number to call because you messed up their nice string of pearls they were setting up, giving them more workload, or messed with their approaches and departures, that's fine.  Like I said above, I'd rather be on the ground talking to, explaining to or writing up documents (especially a NASA form) than having someone crawling over the mangled mess of my airplane trying to figure out which part was part of me or someone else.  &lt;/p&gt;&#xA;" OwnerUserId="8193" LastActivityDate="2015-04-19T23:48:31.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14248" PostTypeId="2" ParentId="952" CreationDate="2015-04-20T00:03:25.083" Score="0" Body="&lt;p&gt;It depends on the year and model and mod of your TB.  Earlier TB's had resistive sensors while the later ones have capacitive sensors.   There are also two sensors in each wing.  The gauge averages the reading because of the wing dihedral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what is the failure mode you are experiencing?   If it's inaccurate fuel readings the original senders had hollow floats that happened to fill with fuel over time, riding lower and lower.  They issued an SB that replaced the senders with solid floats.   But it could also not be your senders.   The latest revision of the engine fluid, temp vertical cluster is Revision D.  Anything before Revision D was notorious for falling out of calibration.  Bad news, is that the 600 dollar cluster, when the plane were in production. now costs 6 thousand so it's better to try to trouble shoot the senders first.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, before we go further, exactly what are you seeing? &lt;/p&gt;&#xA;" OwnerUserId="8193" LastActivityDate="2015-04-20T00:03:25.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14249" PostTypeId="1" AcceptedAnswerId="14250" CreationDate="2015-04-20T02:07:56.123" Score="16" ViewCount="3786" Body="&lt;p&gt;At the time of my retirement in 1999, controllers in France, Spain, Italy, and Greece typically spoke to their native pilots in their native language in spite of the fact that English was/is the international language of aviation and is specified as such by ICAO. Not following the ICAO convention deprived non-native speaking pilots of valuable situational information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know if any of the aforementioned countries have come around to having their controllers always speak English?&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-04-27T19:48:52.297" Title="Do French, Spanish, Italian, and Greek controllers still speak to their native pilots in their native language?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14250" PostTypeId="2" ParentId="14249" CreationDate="2015-04-20T03:53:15.440" Score="13" Body="&lt;p&gt;Well, I just pulled up LEMD on LiveATC and heard some Spanish there. So Madrid clearly speaks Spanish sometimes, although it's probably not very busy right now (5:30 AM there). Archives from midday for LFPO and LFBD (Orly and Bordeaux) have plenty of French. Archives from midday for LGAV (Athens) approach has something definitely non-English (I can't tell if it's Greek or not, but I can't imagine anything else it'd be); LGAV has heavy use of English, but it's not exclusively English. And LiveATC has no feeds for Italy. So, for three of them the answer is definitely &quot;yes, they still speak not-English;&quot; for the last, LiveATC can't answer.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-20T03:53:15.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14251" PostTypeId="1" AcceptedAnswerId="14252" CreationDate="2015-04-20T04:14:13.123" Score="26" ViewCount="7598" Body="&lt;p&gt;I always remember playing FSX as a kid and using the NASA &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;nofollow noreferrer&quot;&gt;F/A-18&lt;/a&gt;, and never thought much about it.  And then I saw the picture of the Space Shuttle on top of the 747 being escorted by these planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does NASA have these fighter jets?&lt;br&gt;&#xA;What are they usually used for?  Military?  Science?  Advertising NASA?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1IUZ5.jpg&quot; alt=&quot;Two NASA F-18&amp;#39;s fly along side a Shuttle Carrier Aircraft 747 carrying Endeavor&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="1696" LastEditDate="2018-04-25T15:01:06.053" LastActivityDate="2018-04-25T15:01:06.053" Title="Why does NASA have F/A-18s?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;nasa&gt;&lt;f-18&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14252" PostTypeId="2" ParentId="14251" CreationDate="2015-04-20T04:21:33.900" Score="37" Body="&lt;p&gt;NASA uses them for pilot training and as chase planes for research aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two-seat F/A-18 support aircraft are normally used for photo or video chase. They are configured to transmit live video pictures from the air back to Dryden so engineers can visually monitor the mission as it is being flown. This feature greatly enhances flight safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's an article from &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-006-DFRC.html&quot;&gt;Armstrong Research Center&lt;/a&gt; with some more information, but that pretty much sums it up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA also currently operates (and has operated) many other military aircraft types, either as chase planes or as subjects of research projects. Some examples off the top of my head include F-15s, F-16s, and of course their ubiquitous B-52s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say &quot;obviously they are battle ready&quot;, but they are not – NASA aircraft are unarmed, and the ones in the photo certainly are carrying no missiles. They may have been fighters in a previous life, but the weaponry has been stripped. &quot;Escort&quot; doesn't mean &quot;fighter escort&quot; in this case!&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-04-20T04:38:04.483" LastActivityDate="2015-04-20T04:38:04.483" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14253" PostTypeId="2" ParentId="14251" CreationDate="2015-04-20T04:23:07.913" Score="15" Body="&lt;p&gt;They're mostly chase planes (source: &lt;a href=&quot;http://www.nasa.gov/centers/armstrong/news/FactSheets/FS-006-DFRC.html&quot;&gt;NASA&lt;/a&gt;). NASA has four of them, two single-seat and two two-seaters. They provide more eyes on the plane for safety purposes (they are in communication with the pilot), and assist NASA's flight test missions. The two-seaters are also useful for photos and videos of flight tests so engineers have more info.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-20T04:23:07.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14254" PostTypeId="2" ParentId="14249" CreationDate="2015-04-20T05:50:39.407" Score="12" Body="&lt;p&gt;As per &lt;a href=&quot;http://www.bazl.admin.ch/dokumentation/grundlagen/02643/index.html?lang=de&amp;amp;download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1acy4Zn4Z2qZpnO2Yuq2Z6gpJCDeoB8hGym162epYbg2c_JjKbNoKSn6A--&quot;&gt;ICAO Annex 10&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;, it is no longer a recommendation, but a requirement that all controllers be able to speak English with an ICAO language proficiency of at least level 4. ICAO Annex 10 states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5.2.1.2 Language to be used&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1.2.1 The air-ground radiotelephony communications&#xA;  shall be conducted in the language normally used by the&#xA;  station on the ground or in the English language.&#xA;  Note 1.— The language normally used by the station on the&#xA;  ground may not necessarily be the language of the State in&#xA;  which it is located. A common language may be agreed upon&#xA;  regionally as a requirement for stations on the ground in that&#xA;  region. &#xA;  Note 2.— The level of language proficiency required for&#xA;  aeronautical radiotelephony communications is specified in&#xA;  the Appendix to Annex 1.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1.2.2 The English language shall be available, on&#xA;  request from any aircraft station, at all stations on the ground&#xA;  serving designated airports and routes used by international air&#xA;  services. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;5.2.1.2.3 The languages available at a given station on the&#xA;  ground shall form part of the Aeronautical Information&#xA;  Publications and other published aeronautical information&#xA;  concerning such facilities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This however doesn't mean that countries cannot still work with their own language and countries like France still work IFR &amp;amp; VFR traffic in their local langauge, whereas some countries like Germany limit German to VFR traffic and emergencies, where plain language can be used. IFR traffic in Germany is conducted in English only.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-04-20T05:50:39.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14256" PostTypeId="2" ParentId="14243" CreationDate="2015-04-20T06:07:59.043" Score="7" Body="&lt;p&gt;The terms you are looking for are &lt;a href=&quot;http://www.skybrary.aero/index.php/Decision_Altitude/Height&quot; rel=&quot;noreferrer&quot;&gt;Decision Altitude (DA) and Decision Height (DH)&lt;/a&gt;. If no &lt;a href=&quot;http://www.skybrary.aero/index.php/Visual_References&quot; rel=&quot;noreferrer&quot;&gt;visual reference&lt;/a&gt; to the runway is established at the DA or DH, a missed approach has to be initiated. So based on the weather and the certification of the airport (CAT I / CAT II / CAT III), the pilot will make the decision to land or not land at the DA/DH.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/H39uM.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.skybrary.aero/index.php/Decision_Altitude/Height&quot; rel=&quot;noreferrer&quot;&gt;SKYbrary&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Decision altitude (DA) is referenced to mean sea level and decision height (DH) is referenced to the threshold elevation.&lt;/p&gt;&#xA;&lt;p&gt;The DH for Category II and III approaches is invariably assessed by reference to a radio altimeter and never a barometric altimeter; therefore the minima can only be expressed as DH and not DA. For approaches with DH of 200ft or higher, radio altimeter reading would be unreliable due to the unevenness of the terrain; therfore a barometric altimeter is always used and the minima may be expressed as DH or DA.&lt;/p&gt;&#xA;&lt;p&gt;The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path. In Category III operations, the required visual reference is that specified for the particular procedure and operation.&lt;/p&gt;&#xA;&lt;p&gt;For convenience where both expressions are used they may be written in the form &amp;quot;decision altitude/height&amp;quot; and abbreviated &amp;quot;DA/H&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Related Videos:&lt;br /&gt;&#xA;&lt;a href=&quot;https://youtu.be/1d0cIM_1vZ4&quot; rel=&quot;noreferrer&quot;&gt;CAT II ILS Approach LGTS&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Related Questions:&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/2301/572&quot;&gt;Is it legal to land in bad visibility conditions without ILS?&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/12626/572&quot;&gt;Are zero visibility landings practical and desirable for commercial aviation?&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/9633/572&quot;&gt;How can landing in zero visibility be safe?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-20T06:13:28.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14257" PostTypeId="2" ParentId="14236" CreationDate="2015-04-20T07:28:26.717" Score="3" Body="&lt;p&gt;Short answer: No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: The stall angle of attack varies with speed, altitude, Mach number and the rate of angle of attack increase, as discussed &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620#3620&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375#6375&quot;&gt;here&lt;/a&gt;. Since the lift curve slope of a wing does not change with the pitch rate, a high pitch rate will indeed increase the stall AoA by up to 50%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed and altitude effects are expressed in the Reynolds number, and this will also shift the AoA up by several degrees when increased from, say,  200,000 to 5,000,000. The influence of the Mach number will really manifest itself above Mach 0.5, but if the leading edge radius is small, it can already make a difference of several degrees between incompressible conditions and Mach 0.3. Stall at higher Mach numbers is more complex, because before lift drops, the wing will experience increasing buffeting, which by itself will limit the operational AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, pitch angle and angle of attack are not the same, but they differ by the flight path angle and the wind angle of attack, which is nonzero if you fly in an up- or downdraft. This is discussed in detail &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb/12720#12720&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your engine or airspeed allows, you can fly a full &lt;a href=&quot;http://en.wikipedia.org/wiki/Aerobatic_maneuver&quot; rel=&quot;nofollow noreferrer&quot;&gt;loop&lt;/a&gt; without ever stalling the airplane.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-21T22:45:36.830" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14258" PostTypeId="1" AcceptedAnswerId="14259" CreationDate="2015-04-20T07:44:20.763" Score="7" ViewCount="11676" Body="&lt;p&gt;Two recent questions and their answers have raised a further question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/13856/are-there-laws-about-how-close-military-aircraft-can-fly-to-passenger-jets-and&quot;&gt;Are there laws about how close military aircraft can fly to passenger jets, and are they enforced?&lt;/a&gt;, we learned that &quot;the military can get as close to other aircraft as they damn well please, through a procedure called Military Assumes Responsibility for Seperation of Aircraft, or MARSA&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/14251/why-are-there-nasa-branded-f-a-18s&quot;&gt;Why are there NASA branded F/A-18s?&lt;/a&gt; we see a picture of closely flying planes, and a comment notes &quot;NASA is a civilian agency&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do the NASA planes fly under MARSA rules or another set of rules for civilian agencies?  Are there other non-military agencies that fall under this rule too?&lt;/p&gt;&#xA;" OwnerUserId="7452" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-04-22T15:43:06.537" Title="What are the rules for close/formation flying of civilian planes?" Tags="&lt;faa-regulations&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14259" PostTypeId="2" ParentId="14258" CreationDate="2015-04-20T09:13:05.630" Score="14" Body="&lt;p&gt;Pilots are allowed to fly as close as they want to each other &lt;em&gt;as long as all parties agree to it&lt;/em&gt; and feel safe doing so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air Traffic Control cannot guarantee separation for planes in formation flight,So this will only be done under VFR and in VMC, where pilots can maintain visual separation from each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many stunt fliers are civilian pilots and will routinely fly in close formation as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other notable example of civilian formation flight include &lt;a href=&quot;http://en.wikipedia.org/wiki/MythBusters_%282011_season%29#Episode_178_.E2.80.93_.22Toilet_Bomb.22&quot;&gt;Mythbusters testing airplane fuel efficiency in formation&lt;/a&gt; and &lt;a href=&quot;http://aviationweek.com/commercial-aviation/video-airbus-a350-900-formation-flight&quot;&gt;Airbus' publicity stunt with 5 A350s&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-04-20T10:14:36.153" LastActivityDate="2015-04-20T10:14:36.153" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14261" PostTypeId="1" AcceptedAnswerId="14262" CreationDate="2015-04-20T10:18:49.310" Score="35" ViewCount="5337" Body="&lt;p&gt;In general, are there any differences between the engines on a multi-engine aircraft? Are engines designed to be specifically for the left or right wing, or inboard or outboard for a 4-engine aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about the tail engine on a tri-jet like the DC-10? Is it the same as the two wing-mounted engines?&lt;/p&gt;&#xA;" OwnerUserId="282" LastActivityDate="2018-05-04T23:41:35.433" Title="Are all the engines on a multi-engine plane the same?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14262" PostTypeId="2" ParentId="14261" CreationDate="2015-04-20T10:42:04.120" Score="32" Body="&lt;p&gt;Generally yes, but not always. If you include the &lt;a href=&quot;http://en.wikipedia.org/wiki/Auxiliary_power_unit&quot;&gt;APU&lt;/a&gt; as an engine, the answer would need to be different, but I understand your question concerns just the engines used for propulsion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For jets, the direction of rotation doesn't make much of a difference, so the same engines can be used on all stations. However, with propellers the swirl does influence flying characteristics, especially at low speed, so special left- and right turning versions of turboprop and piston engines are available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintenance and logistics become much simpler if only one type of engine is used. In the past, not so much emphasis was placed on this, so some airplanes used different types of engines. Examples were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_B-36_Peacemaker#Addition_of_jet_propulsion&quot;&gt;Convair B-36B&lt;/a&gt;, which combined piston and jet engines in the same airframe&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_G.38&quot;&gt;Junkers G-38&lt;/a&gt;, which used a Junkers L88 inboard and a Junkers L8 outboard. Later, the outboard engines were also changed to the L88. This can be seen from the number of propeller blades: If the outer engines drive a two-bladed propeller, it is the earlier version with the L8.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aviastar.org/air/england/hawker_trident.php&quot;&gt;Hawker-Siddeley Trident 3&lt;/a&gt;, which was almost a four-engined jet, because it had a small, tail-mounted RB-162 engine in addition to the three tail-mounted RB-163 Spey to provide thrust on takeoff.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19880548000&quot;&gt;Rutan Voyager&lt;/a&gt;, which used a bigger front and a smaller rear engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-04-21T07:31:31.580" LastActivityDate="2015-04-21T07:31:31.580" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14263" PostTypeId="1" AcceptedAnswerId="14264" CreationDate="2015-04-20T11:47:13.337" Score="31" ViewCount="8599" Body="&lt;p&gt;In some models of multi-engine airplanes there is a switch labelled something similar to &quot;prop sync&quot; or &quot;engine sync&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is engine synchronization?&lt;/li&gt;&#xA;&lt;li&gt;How is it achieved?&lt;/li&gt;&#xA;&lt;li&gt;Why is it important to use?&lt;/li&gt;&#xA;&lt;li&gt;What happens if you don't use it?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="69" LastEditDate="2015-04-20T21:16:06.513" LastActivityDate="2020-07-12T20:40:56.997" Title="What is propeller / engine sync and how does it work?" Tags="&lt;aircraft-systems&gt;&lt;multi-engine&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14264" PostTypeId="2" ParentId="14263" CreationDate="2015-04-20T13:12:51.360" Score="16" Body="&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/Propeller_synchronization&quot;&gt;Wikipedidea&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In aviation, propeller synchronization is a mechanism that automatically synchronizes all propellers of a multi-engine, propeller-driven aircraft so that they rotate at the same speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for why its used the article states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Propeller synchronization serves mainly to increase the comfort of crew and passengers, since its primary purpose is to reduce the “beats” generated by propellers that are turning at slightly different speeds. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for what happens if you don't use it, according to the article &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Synchronization is not normally necessary for proper operation of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-04-20T14:38:04.167" LastActivityDate="2015-04-20T14:38:04.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14265" PostTypeId="2" ParentId="14263" CreationDate="2015-04-20T13:21:55.523" Score="26" Body="&lt;p&gt;I don't know how it is achieved, but here is the reason:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have two sources of the same noise, with nearly the same frequency, the sum of both noises will be a noise of slowly increasing and decreasing volume. It's called &lt;a href=&quot;http://en.wikipedia.org/wiki/Beat_%28acoustics%29&quot; rel=&quot;noreferrer&quot;&gt;beat&lt;/a&gt; and can become very annoying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The math says&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\sin(2\pi f_1t)+\sin(2\pi f_2t)=2\cdot\sin\left(2\pi \frac{f_1+f_2}{2}t\right)\cdot\cos\left(2\pi \frac{f_1-f_2}{2}t\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To demonstrate this, there you see two sinus-tones of almost same frequency, and what happens if you mix them:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lF5Qz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blue curve is of frequency $(f_1-f_2)/2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As example, one machine running at 3000rpm and one at 3030rpm results in a noise which increases for one seconds before it decreases within one second again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As said, I don't know how it is done, but synchronization must be done very precisely to avoid this beat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is what happens if the two noises do not have the same volume. One of the curves has three times the amplitude of the other. The envelope is not a pure sin function, but the blue function fits it quite well.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/lhG1N.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-04-20T21:10:52.720" LastActivityDate="2015-04-20T21:10:52.720" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14266" PostTypeId="2" ParentId="14263" CreationDate="2015-04-20T14:53:19.190" Score="21" Body="&lt;p&gt;On the &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Ju_52&quot; rel=&quot;noreferrer&quot;&gt;Junkers Ju-52&lt;/a&gt; the pilot had two little discs which rotated with the beat frequency between two engines. The upper left one would show the beat frequency between the left and the center engine, and the lower right one that between the center and right engines. The pilot would try to stop them rotating by advancing or retarding the throttles, equalizing engine speed in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/S8F8h.jpg&quot; alt=&quot;Instrument panel of the Lufthansa Ju-52 D-AQUI&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I highlighted the synchronization indicator in the picture above (&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/1/1/3/1416311.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Running all engines at the same speed helps to fly straight and reduces vibrations. Not only is one distinctive engine frequency removed by equalizing it with the other, also the beat frequency is deleted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry, I cannot answer this for the Beech Baron. I've flown it only once and don't remember any instruments (other than my ears) which would help &#xA;with synchronization.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-28T22:20:06.993" LastActivityDate="2016-01-28T22:20:06.993" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14267" PostTypeId="2" ParentId="14221" CreationDate="2015-04-20T15:03:08.500" Score="6" Body="&lt;p&gt;It needs to be airworthy, as per 91.403, which is defined to include compliance with all ADs:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) No person may operate an aircraft for which a manufacturer's&#xA;  maintenance manual or instructions for continued airworthiness has&#xA;  been issued that contains an airworthiness limitations section unless&#xA;  the mandatory replacement times, inspection intervals, and related&#xA;  procedures specified in that section or alternative inspection&#xA;  intervals and related procedures set forth in an operations&#xA;  specification approved by the Administrator under part 121 or 135 of&#xA;  this chapter or in accordance with an inspection program approved&#xA;  under § 91.409(e) have been complied with.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It needs a 100-hour, as per 91.409:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Except as provided in paragraph (c) of this section, no person may&#xA;  operate an aircraft carrying any person (other than a crewmember) for&#xA;  hire ... unless within the preceding 100&#xA;  hours of time in service the aircraft has received an annual or&#xA;  100-hour inspection and been approved for return to service in&#xA;  accordance with part 43 of this chapter or has received an inspection&#xA;  for the issuance of an airworthiness certificate in accordance with&#xA;  part 21 of this chapter. The 100-hour limitation may be exceeded by&#xA;  not more than 10 hours while en route to reach a place where the&#xA;  inspection can be done. The excess time used to reach a place where&#xA;  the inspection can be done must be included in computing the next 100&#xA;  hours of time in service.&#xA;  (source: &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.409&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR Part 91.409&lt;/a&gt;). &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/part-43/appendix-D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 43 Appendix D&lt;/a&gt; specifies the items which need to be checked in the 100-hour inspection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it needs to have all the other necessary mechanic's inspections, including ELT, transponder/pitot static system, etc., and pilot checks, like VOR accuracy.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-04-20T18:06:14.290" LastActivityDate="2015-04-20T18:06:14.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14268" PostTypeId="2" ParentId="14261" CreationDate="2015-04-20T15:12:49.470" Score="6" Body="&lt;p&gt;The place to find the true answer is in the Type Certificate Data Sheet. This document will tell you exactly what engines can be installed on an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/Frameset?OpenPage&quot; rel=&quot;nofollow&quot;&gt;For example on the DC-10-10:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3 General Electric CF6-6D, CF6-6D1, CF6-6D1A, CF6-6K or CF6-6K 2 Turbofan Engines. (CF6-6D and CF6-6K engines may be intermixed in accordance with Appendix XXII of the applicable FAA Approved Airplane Flight Manual. CF6-6D1 and CF6-6D1A engines may be intermixed in accordance with page 2.1 of Section IVB of applicable FAA Approved Airplane Flight Manual.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-04-21T00:38:54.577" LastActivityDate="2015-04-21T00:38:54.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14269" PostTypeId="2" ParentId="14258" CreationDate="2015-04-20T15:21:52.500" Score="12" Body="&lt;p&gt;You already have a good answer on separation specifically, but it's worth noting that there are a few general rules about formation flights in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most specific formation rules are in 91.111:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.111   Operating near other aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may operate an aircraft so close to another aircraft as&#xA;  to create a collision hazard.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may operate an aircraft in formation flight except by&#xA;  arrangement with the pilot in command of each aircraft in the&#xA;  formation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No person may operate an aircraft, carrying passengers for hire,&#xA;  in formation flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Charity flights are exempt from air carrier (part 119) and drug/alcohol testing (part 120) requirements, but only if the flight is not a formation flight (among other conditions):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.146   Passenger-carrying flights for the benefit of a charitable,&#xA;  nonprofit, or community event.&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) The flight is not an aerobatic or a formation flight;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You must provide formation details if you're filing a VFR flight plan:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.153   VFR flight plan: Information required.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Information required. Unless otherwise authorized by ATC, each&#xA;  person filing a VFR flight plan shall include in it the following&#xA;  information:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The type of the aircraft or, in the case of a formation flight,&#xA;  the type of each aircraft and the number of aircraft in the formation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The full name and address of the pilot in command or, in the case&#xA;  of a formation flight, the formation commander.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-22T15:43:06.537" LastActivityDate="2015-04-22T15:43:06.537" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14270" PostTypeId="2" ParentId="14246" CreationDate="2015-04-20T15:35:50.027" Score="10" Body="&lt;p&gt;The short answer is yes, they are definitely expected to listen and act accordingly. This is one example of &lt;a href=&quot;http://en.wikipedia.org/wiki/Situation_awareness&quot; rel=&quot;nofollow noreferrer&quot;&gt;situational awareness&lt;/a&gt; in aviation, and pilots are expected to use all useful information sources to maintain awareness of what's going on around them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A nice example is &lt;a href=&quot;https://www.youtube.com/watch?v=gSwNiuxYJHE&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt; where the crew of a US Airways aircraft avoided an accident. There was heavy fog at the airport, and while the US Airways flight was waiting for takeoff clearance a United aircraft ended up on a runway instead of a taxiway. The controller couldn't see the runways because of the fog and she believed the United aircraft was on a taxiway, so she gave the US Airways flight clearance to take off even though the United pilot said several times that they were on a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Airways pilot had heard the discussion (actually, almost a debate) between the controller and the United pilot, and he refused the takeoff clearance because he wasn't confident that the situation was under control. It's well worth watching the whole thing, but the key exchange is this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ATC: [...] USAir 2998, runway 5R, fly runway heading, cleared for&#xA;  takeoff&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;US2998: Uh, tower, USAir 2998, 'til we figure out what's going on down&#xA;  there, we're just gonna stay clear of all runways&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This level of awareness is expected of all pilots, including light aircraft pilots at uncontrolled fields. Although in that situation there's the additional complication that there may be aircraft around that don't even have radios!&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-12-02T02:59:08.787" LastActivityDate="2016-12-02T02:59:08.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14271" PostTypeId="2" ParentId="14263" CreationDate="2015-04-20T15:44:38.140" Score="4" Body="&lt;p&gt;The engines using prop sync will be constant speed props. Constant rpm is maintained with a &lt;a href=&quot;http://en.wikipedia.org/wiki/Governor_%28device%29&quot; rel=&quot;nofollow&quot;&gt;governor&lt;/a&gt; of some kind that adjusts the pitch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This governor can be tuned by the prop sync to speed up or slow down one prop by adjusting it.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-04-20T15:44:38.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14272" PostTypeId="1" AcceptedAnswerId="14273" CreationDate="2015-04-20T16:15:38.837" Score="1" ViewCount="345" Body="&lt;p&gt;Is there something like an ignition key for planes?&lt;br&gt;&#xA;Or could one &quot;just enter&quot; and fly away if they could?&lt;/p&gt;&#xA;" OwnerUserId="8198" LastActivityDate="2015-04-20T16:23:11.060" Title="Is there something like an ignition key for planes?" Tags="&lt;safety&gt;&lt;cockpit&gt;&lt;security&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-04-20T16:21:18.263" ContentLicense="CC BY-SA 3.0" />
  <row Id="14273" PostTypeId="2" ParentId="14272" CreationDate="2015-04-20T16:23:11.060" Score="1" Body="&lt;p&gt;The planes I have trained in (single engined Piper Cherokees/Warriors) do indeed have an ignition key, without which the magneto system (which drives the spark plugs) and the starter cannot be engaged. Without being certain, I would assume the same goes for other small GA aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you get to airliners I have no idea whether there are keys for locking the controls - as the controls are much more complex, the keys probably won't be directly connected to ignition systems or starters, and I wouldn't be surprised if the primary security method is keeping doors locked.&lt;/p&gt;&#xA;" OwnerUserId="4162" LastActivityDate="2015-04-20T16:23:11.060" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14274" PostTypeId="2" ParentId="14091" CreationDate="2015-04-20T17:42:00.270" Score="6" Body="&lt;p&gt;First, one small clarification: ATC doesn't offer &lt;em&gt;any&lt;/em&gt; services to an aircraft on a VFR flight plan unless you call and request them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=wx8rglGpZd0&amp;amp;feature=youtu.be&quot; rel=&quot;nofollow noreferrer&quot;&gt;This short &lt;em&gt;Ask ATC&lt;/em&gt; video&lt;/a&gt; from AOPA has some useful comments:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Controllers don't know anything about your VFR flight plan&lt;/li&gt;&#xA;&lt;li&gt;VFR flight plans are for search and rescue purposes only&lt;/li&gt;&#xA;&lt;li&gt;Even if you call ATC and request flight following, they only enter the destination into their system, not your route (I assume that's because your route could be 'follow that river and then that interstate')&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The key point is that VFR flight plans are recorded and managed by FSS, not ATC. So, does FSS accept whatever they're given? I couldn't find a direct answer to that question, but the FAA's &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/7110.10x_w_chg2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;procedures&lt;/a&gt; for receiving and handling VFR flight plans (see Chapter 6) don't include any steps to &quot;validate&quot; the plan (whatever that would mean anyway). Although there's a lot of detailed, tedious information there so I may have missed something :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2005/April/200504_Features_Rescue_me.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this AOPA explanation&lt;/a&gt; implies that no one even looks at the route unless it's as part of the SAR process:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;ETA plus one hour&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Within a half-hour of becoming overdue or at ETA plus one hour, the&#xA;  search is widened by sending an INREQ (information request) to flight&#xA;  service facilities along the route (which is why the route of flight&#xA;  is specified on the flight plan). If [the pilot] had been on an IFR flight&#xA;  plan, the INREQ would have gone out at ETA plus 30 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The bottom line seems to be that no one really cares about your VFR flight plan unless it's actually needed to find you. So even if you can enter a nonsense plan, it wouldn't be a very good idea.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-02-01T21:57:53.493" LastActivityDate="2018-02-01T21:57:53.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14275" PostTypeId="1" AcceptedAnswerId="14278" CreationDate="2015-04-20T17:45:23.320" Score="18" ViewCount="13796" Body="&lt;p&gt;I'm a US-citizen living in Japan, and the costs here are insane ($500 per hour). So I'm thinking to go to the US or Australia for my pilot's license, but how long am I'm going to need to live there? Could it be done in 2-3 months? Less?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/questions/627/how-much-generally-speaking-does-it-cost-to-learn-how-to-fly&quot;&gt;question&lt;/a&gt; discusses the cost of learning to fly, and it's mentioned that people often take a year (flying once a week) to see the hours. My question is: reasonably speaking, how quickly can someone get their license?  I'm not actually looking to go from &quot;zero to hero&quot; in record time, I do want to learn the material and enjoy the process. But wanted to have a rough idea of the lower limit so I can plan for the total costs (housing, time away from work).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need 40-50 hours of flight time, and you fly 2-3 times a week, what is the typical duration of these instructional flights?  How many hours can someone realistically book in a week (I hear flights get cancelled)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;In reply to the comment about individual ability…&lt;/em&gt; I have a high-IQ and have taught myself many things throughout my life. I'm a software engineer with 20+ years experience (created my first commercial software application around age 12), I've authored several top-selling Japanese language books, I taught myself photography and have two Page-One credits in the NYTimes, I learned freediving and 9 months later I won an event in a competition in Japan and ranked 11th nationally, etc. When I put my mind to something I'm focused and disciplined. How much does it really depend on my ability and how much depends on class hours and flight time?&lt;/p&gt;&#xA;" OwnerUserId="8201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-30T05:11:00.030" Title="How quickly can someone learn to fly?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;ppl&gt;&lt;australia&gt;&lt;flight-school&gt;" AnswerCount="8" CommentCount="13" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14277" PostTypeId="2" ParentId="14275" CreationDate="2015-04-20T18:13:28.137" Score="14" Body="&lt;p&gt;I go once or twice a week if the weather holds and I'm up to almost 8 months (and I am still not done (PPL)). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I work with a guy who religiously went 3 days a week and said he got it done (at a part 61 school) in 6 months (almost exactly). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The limiting factors are of course money (which does not sound like you are worried about if you are planning an endeavor like this). And of course weather (which you can mitigate by going to a place in the country that has better year round weather like the south west), if you come during the summer and get 3 solid months of clear days and potentially never have a flight canceled you will be good. I have had 3 flights canceled in the past 3 weeks due to high wind or rain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for booking you can book as many hours as your instructor/aircraft will allow. Some instructors are part time which can limit how much you can book, and some schools have only a few planes but generally allow you to book way in advance so if you have the plane and instructor you can book every hour of daylight if you like. Keep in mind that trainer planes have 100 hour inspections and will be out for maintenance when another student inevitably has a prop strike...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for ability that depends on a lot of things. You will most likely get the maneuvers down fast and then it will be all landing work. If you get those down fast (and they say the more frequently you fly the better it is) you can be done quickly.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can mitigate some of this by self teaching yourself the ground material, although some schools (if not all) will require you to sit for a certain amount of ground lesson hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of hours you get in a single day will depend on what you are doing and how long you can be up for. The way I was taught there was usually some pre flight instruction (outlining what we were going to do). Then I had to preflight the plane. Then get in, taxi out (I was at KPNE, so there was a solid amount of taxi traffic to contend with on occasion) go practice maneuvers or stay in the pattern and practice landings then some post flight discussion. All told for an hour and a half on the Hobbs I would some times be at the airport for 4 hours or more. I would think that realistically (assuming you need to eat lunch in the middle) and discuss things on the ground etc, you could get maybe 5 hours of actual flight time in, in a day. This will also depend on the season since the days are significantly shorter in the winter. Up hear in the north east there is a solid extra 2 hours of day VFR time in the summer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit 2&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could on some level use a sim before you went about this to familiarize yourself with the aircraft instruments, how they work, and what certain control inputs will result in. A decent setup using X-Plane will only cost you a few hundred (USD) and be a lot of fun in its own right. The issue you will hit is that to much sim flying can result in BAD habit development. Sims are a great learning tool but don't always feel like the real thing so as long as you use it as a learning tool you will be fine. Some sim's even allow for simulated ATC communication which can really help you hone in your radio skills (something that will be overwhelming at first.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit 3&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see in the comments that you wish to one day fly a P-51. Assuming you are talking about doing so solo its worth nothing that the P-51 is a &quot;Tail Dragger&quot; also known as conventional landing gear. Most modern trainers have tricycle landing gear so you will have to get checked out in a conventional gear plane. You will also need a high performance rating to fly a plane with that much power as well as complex for the folding landing gear. While we are on the topic you mention flying lots of different types of planes this is not as simple as you would think. Most places will require type specific time (time in that particular model of aircraft or a very similar one) before letting you fly/rent it. To fly in lots of different aircraft right after having you license you will be spending lots of time with instructors in the plane as apposed to solo time.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-28T13:25:21.743" LastActivityDate="2016-03-28T13:25:21.743" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14278" PostTypeId="2" ParentId="14275" CreationDate="2015-04-20T18:20:08.217" Score="19" Body="&lt;p&gt;The absolute minimum would be about 45 hours. The FAA requires 40 hours of flight time, the completion of an aeronautical knowledge course, a written test, and a flight test. This assumes that you can read and memorize all the necessary aeronautical knowledge in an hour and a half.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the realm of humans who like to eat and sleep and actually learn and such, you might be able to do it a little faster than 21 days. &lt;a href=&quot;http://www.sunstateaviation.com/accelppl172.html&quot;&gt;This flight school&lt;/a&gt; offers an accelerated PPL program that they list as taking 21 days, and they &lt;a href=&quot;http://www.sunstateaviation.com/faq.html#Q2&quot;&gt;say&lt;/a&gt; that &quot;[a]ny of these courses can be completed in less time than what is listed above, however the courses are based on the average time to completion.&quot; Of course, if there's a lot of inclement weather, that could slow things down.&lt;/p&gt;&#xA;" OwnerUserId="3170" LastActivityDate="2015-04-20T18:20:08.217" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14281" PostTypeId="2" ParentId="14275" CreationDate="2015-04-20T21:37:01.777" Score="41" Body="&lt;p&gt;I did it in 17 days - start to finish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did flight school in Arizona.  Before I went, I got the PPL study guide, MS Flight Simulator complete with a yoke, pedals, and throttle quadrant... and put in dozens of hours just learning the instrument scan and practicing virtual stuff.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I got to the flight school, I already knew the parts of the plane, and what each control did.  I knew about maps and plotting courses.  I understood the physics of flight.  I knew about VORs, VASIs, NDBs... I knew about stalls and corrective procedures - from an academic standpoint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such, my under-the-hood training was by-the-numbers.  My seat of the pants stuff was only hampered the first few days by the awful flying conditions of AZ in July heat.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, I aced the written, and did my 3 required solos in two days.  I went to a flight school run by a Gold Seal licensed FAA examiner so I didn't have to depend on the FAA to squeeze me in.  And I passed.  17 days.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ONLY flew tricycle gear stuff.  No taildraggers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the serious prep beforehand, there were three main drivers for my success:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;I flew at LEAST once a day - many times twice.&lt;/li&gt;&#xA;&lt;li&gt;I wanted this more than anything I had ever wanted before.  &lt;/li&gt;&#xA;&lt;li&gt;I only had enough money and vacation accrued to be there for 3 weeks total - no more.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Best of luck!&lt;/p&gt;&#xA;" OwnerUserId="8208" LastActivityDate="2015-04-20T21:37:01.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14282" PostTypeId="2" ParentId="14261" CreationDate="2015-04-20T23:28:45.947" Score="7" Body="&lt;p&gt;As this image shows the Navy flew a plane with two propeller engines and two jet engines.  &lt;a href=&quot;http://www.maam.org/neptune/p2_1.html#piston&quot; rel=&quot;noreferrer&quot;&gt;Read more about it here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vqmVd.jpg&quot; alt=&quot;Navy P2V in flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From wikipedia: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Beginning with the P2V-5F model, the Neptune became one of the first&#xA;  aircraft in operational service to be fitted with both piston and jet&#xA;  engines. The Convair B-36, several Boeing C-97 Stratofreighter,&#xA;  Fairchild C-123 Provider, and Avro Shackleton aircraft were also so&#xA;  equipped. To save the weight and complexity of two separate fuel&#xA;  systems, the jet engines on the P2Vs did not burn jet fuel- they&#xA;  burned the same fuel as the piston engines: 115–145 Avgas. The jet&#xA;  pods were fitted with intake doors that were kept closed when the&#xA;  J-34s were not running to prevent them from windmilling, allowing for&#xA;  economical piston-engine-only long-endurance search and patrol&#xA;  operations. In normal U.S. Navy operations, the jet engines were run&#xA;  at full power (97%) to expedite and assure all takeoffs, then shut&#xA;  down when the aircraft reached a safe altitude. Also, the jets were&#xA;  started and kept running at flight idle during low-altitude (500 feet&#xA;  during the day and 1,000 feet at night) anti-submarine and/or&#xA;  anti-shipping operations at sea as a safety measure in case one of the&#xA;  radials developed problems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8210" LastEditorUserId="1467" LastEditDate="2015-08-08T16:04:56.370" LastActivityDate="2015-08-08T16:04:56.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14283" PostTypeId="1" AcceptedAnswerId="14289" CreationDate="2015-04-21T02:51:30.020" Score="26" ViewCount="15509" Body="&lt;p&gt;Paper airplanes' wings are completely flat, unlike the droplet shaped curvature of a full sized wing. How does a flat wing generate any lift if both sides have the same air pressure?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastEditorUserId="62" LastEditDate="2018-01-05T02:16:21.573" LastActivityDate="2018-12-19T22:56:20.253" Title="How do paper airplanes create lift if their wings are flat?" Tags="&lt;aerodynamics&gt;&lt;paper-airplane&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14285" PostTypeId="2" ParentId="14236" CreationDate="2015-04-21T05:55:33.363" Score="0" Body="&lt;p&gt;For a given wing configuration eg leading/trailing flap, sweep etc, the stall will occur at the same AoA in incompressible flow (low speed, low alt flight) - that's assuming you can clearly define the stall as some fighter aircraft don't have a sudden classical lift break, rather their stall might be defined by rapid drag rise, controllability, handling issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For compressible flow, ie flight at high Mach number, the stall AoA will reduce: Stall AoA at 300KCAS/sea-level is greater than the stall AoA at 30,000ft/300KCAS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two effects at play here... Compressibility and Viscosity. The effect of compressibility is the predominant one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Viscosity (Reynolds number). For a given wing design and configuration, as you go up in altitude, the density of the air decreases, while viscosity increases with lower temp. This has a small effect on Reynolds Number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compressibility: energy lost in compressing the air is significant at higher mach, which is why you see lower AoA for a given defined stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, buffet onset is not always a defining attribute of the stall as some jet fighters will experience buffet at very low AoA eg 6-7 degrees, well before the defined stall.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastEditorUserId="8030" LastEditDate="2015-04-21T17:37:23.357" LastActivityDate="2015-04-21T17:37:23.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14286" PostTypeId="1" AcceptedAnswerId="14295" CreationDate="2015-04-21T06:09:17.543" Score="14" ViewCount="61815" Body="&lt;p&gt;I've always loved the air force. However, my main goal is to become an airline pilot. Would joining the air force affect becoming a commercial airline pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am asking because if I join the air force, I am committed to seven years of service. Would this put me behind other pilots? Or, do airlines like pilots with military backgrounds?&lt;/p&gt;&#xA;" OwnerUserId="8216" LastEditorUserId="15311" LastEditDate="2017-12-19T14:02:37.477" LastActivityDate="2017-12-20T15:07:58.820" Title="Is joining the air force a good way to become an airline pilot?" Tags="&lt;military&gt;&lt;career&gt;&lt;airline-pilot&gt;&lt;flight-school&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14287" PostTypeId="2" ParentId="14275" CreationDate="2015-04-21T06:13:23.417" Score="10" Body="&lt;p&gt;Yes, at least in the US it is completely reasonable to do it in 2-3 months. I believe you can achieve this easily in a month's time if you're doing it full time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following applies to the US,  where I'm most familiar with the rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The process in the US as an alien is as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Find a flight school and notify them that you'd like to begin flight training&lt;/li&gt;&#xA;&lt;li&gt;Receive authorization from the TSA to begin flight training&lt;/li&gt;&#xA;&lt;li&gt;Get a Medical Exam&lt;/li&gt;&#xA;&lt;li&gt;Fly 40 hours (more on exact requirement below)&lt;/li&gt;&#xA;&lt;li&gt;Receive an endorsement to take the written knowledge test&lt;/li&gt;&#xA;&lt;li&gt;Take the Written Knowledge Test&lt;/li&gt;&#xA;&lt;li&gt;Receive an endorsement to take the practical test&lt;/li&gt;&#xA;&lt;li&gt;Take the practical test&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The 40 flight hours have some additional requirements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;20 hours with an instructor&#xA;&lt;ul&gt;&#xA;&lt;li&gt;3 hours cross country (where the flight leg is at least 50 nautical miles)&lt;/li&gt;&#xA;&lt;li&gt;3 hours of night flying&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1 cross-country flight of at least 100 nautical miles&lt;/li&gt;&#xA;&lt;li&gt;10 take offs and landings to a full stop&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;3 hours of instrument flying (you wear a view-limiting device like &lt;a href=&quot;http://www.sportys.com/pilotshop/francis-ifr-hood.html&quot;&gt;this&lt;/a&gt; one)&lt;/li&gt;&#xA;&lt;li&gt;3 hours of flying within 60 days of the practical exam&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;10 hours of solo flying&#xA;&lt;ul&gt;&#xA;&lt;li&gt;5 hours of cross-countries&lt;/li&gt;&#xA;&lt;li&gt;1 cross-country flight of at least 150 nautical miles with landings at 3 different airports&lt;/li&gt;&#xA;&lt;li&gt;3 take offs and landings at an airport with a controlled tower&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here are some tips to accelerate the process:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you're still in Japan:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Identify a flight school that is familiar with accelerated flight training, for example &lt;a href=&quot;http://www.doubleeagleaviation.com/tucson_flight_school.php#4&quot;&gt;Double Eagle Aviation&lt;/a&gt; or &lt;a href=&quot;http://www.tailwheelsetc.com/private_pilot.html&quot;&gt;Tailwheels Etc.&lt;/a&gt;. You should go to a place with good weather and choose a time of the year to maximize flying days (e.g. sunny, little wind, cool days or low altitude). Call and notify them that you'd like to begin flight training (check availability, schedule the course).&lt;/li&gt;&#xA;&lt;li&gt;Get the endorsement for the FAA Written Knowledge Exam. You can do this through an online ground school course, like &lt;a href=&quot;http://www.sportys.com/pilotshop/learn-to-fly/private-pilot-learn-to-fly-course/learn-to-fly-course-online-private-pilot-test-prep.html&quot;&gt;Sportys&lt;/a&gt; or &lt;a href=&quot;http://www.kingschools.com/ground-school/private-pilot/courses/written&quot;&gt;King Schools&lt;/a&gt;. There are various others you can find online, just make sure they will provide you with an &lt;strong&gt;endorsement&lt;/strong&gt; for the FAA written exam.&lt;/li&gt;&#xA;&lt;li&gt;Become familiar with the &lt;a href=&quot;https://www.flightschoolcandidates.gov&quot;&gt;TSA's Alien Flight Student Program&lt;/a&gt; and review timelines, process, and requirements. You will need to be fingerprinted at specific locations and the process can take a week or two.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Then, as soon as you land in the USA, get fingerprinted for the AFSP and while you're waiting for authorization, get your medical exam and take the written knowledge test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this helps!!!!&lt;/p&gt;&#xA;" OwnerUserId="8139" LastActivityDate="2015-04-21T06:13:23.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14288" PostTypeId="2" ParentId="14283" CreationDate="2015-04-21T06:45:02.943" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How does a flat wing generate any lift if both sides have the same air pressure?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The two sides &lt;strong&gt;do not&lt;/strong&gt; have the same pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flat plane can still produce lift (think of putting a plate out of the window of a moving car, if you point it slightly upwards it will strongly push upwards, that's lift). The main reason is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Kutta_condition&quot;&gt;Kutta condition&lt;/a&gt; that must be satisfied at the trailing edge: this will create circulation around the flat plate, generate a pressure difference and thus generate lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paper airplanes will inevitably come down not because they do not produce lift, but because they also have drag (and no thrust), that will slow them down and hence reduce the lift generated.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-04-21T06:45:02.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14289" PostTypeId="2" ParentId="14283" CreationDate="2015-04-21T06:47:48.397" Score="41" Body="&lt;p&gt;Paper airplanes create lift just like any other airplane. Don't let the wing cross section confuse you; what the air &quot;sees&quot; is a different shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a flat plate flows through air at a positive angle of attack, the stagnation point of the flow (where air splits into an upper and a lower flow path) sits slightly below the forward edge of the wing. Now the streamline just above the one which hits the stagnation point has to negotiate the sharp corner of the leading edge, which will cause it to separate from the surface. This creates a small separation bubble which to the streamlines further up looks like a round leading edge, and since the rest of the wing has no curvature, the flow will attach again soon. The bigger the angle of attack gets, the farther back the stagnation point will be and the bigger the separation bubble becomes. At some point, which is promoted by leading edge sweep, the separated flow will not reattach, but produce a vortex, like the vortex which provides lift on delta wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NmQjv.jpg&quot; alt=&quot;Visualisation of the flow around a flat plate at moderate angle of attack&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture above is from a simulation; see the &lt;a href=&quot;https://www.youtube.com/watch?v=KldLqShzCRM&quot; rel=&quot;noreferrer&quot;&gt;full video here&lt;/a&gt;. Note the red color on the forward part of the upper side: This indicates low local pressure, which is needed to make the outer air negotiate the leading edge plus the separation bubble (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/13957/does-the-downwash-created-by-induced-drag-increase-or-decrease-lift/13978#13978&quot;&gt;here&lt;/a&gt; for an explanation on the molecular level). In the separation bubble, low pressure is &lt;strong&gt;not&lt;/strong&gt; accompanied by high flow speed since the separation turbulence has eaten up most of the kinetic energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual nose radius of the paper wing does not matter, and it might even be zero (like when you fit razor blades to the leading edge): The air will create its own airfoil shape by padding with separated air what cannot be reached with attached flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paper airplanes have a low enough wing loading that their angle of attack is low and the separation does not become too big. All it needs is a center of gravity at the quarter chord of the wing; that is why you need to fold the piece of paper first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is interesting to watch a slightly tail-heavy, delta-shaped paper airplane fly: It will gradually reduce speed and will start to rock its wings when it approaches stall. Once one wing is going down, the sudden increase in its local AoA will increase lift so much that the rolling motion reverses, without noticeable yawing. The delta-shaped flat plate has effective roll damping right into the stall. The lack of yaw is mostly due to the high yaw inertia, but indicates also that drag buildup is moderate at best.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, after a few periods of rocking the nose will drop and it will pick up speed like any well-behaved airplane.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-09T14:28:52.287" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14290" PostTypeId="2" ParentId="14241" CreationDate="2015-04-21T09:47:45.697" Score="5" Body="&lt;p&gt;Fuel injectors in GA piston engines are actually fixed nozzles, so short of fuel contamination, are not so easy to clog,since the only thing that can  be deposited with clean fuel is the blue dye in the avgas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 8 years maintaining a fleet of 6 to 8 injected Continental engines, running 200-700 hours / year, I did not see a fuel-deposit blocked nozzle. Deposits did change the flow rate enough for us to routinely clean them ultrasonically (our pilots were cruising lean of peak, and would start complaining), but removing, cleaning and reinstalling the injector nozzles was a routine, straightforward and scheduled event in my experience.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With position tuned nozzles, as current Continental ones are, you need to be careful to get them back to their correct position, just like GAMI ones, but it's not rocket engineering. The torques for installation are in the manuals, and they are not the most challenging item to work on (one b-nut and one pipe thread per nozzle) on the average GA engine. There's no need for special additives.&lt;/p&gt;&#xA;" OwnerUserId="7487" LastEditorUserId="3386" LastEditDate="2015-04-21T14:23:54.670" LastActivityDate="2015-04-21T14:23:54.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14293" PostTypeId="2" ParentId="14263" CreationDate="2015-04-21T15:32:36.257" Score="3" Body="&lt;p&gt;It's just an automatic system to do prop speed and/or blade location synchronization.  On a multi without it, one does it manually by adjusting the prop pitch controls.  If the automatic system is not used, it can still be done manually.  Prop sync is typically required to be turned off during critical phases of flight (takeoff/landing).&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2015-04-21T15:32:36.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14294" PostTypeId="2" ParentId="5015" CreationDate="2015-04-21T18:30:15.483" Score="6" Body="&lt;p&gt;Just for clarification sake, Thunderbird 5 is the LEAD solo, not the Opposing Solo.  Opposing Solo is Thunderbird 6.  The 5 is upside-down because During the show he spends the most time upside-down.  On crowd passes, and show center, he is usually inverted.&#xA;Also, the F-4 Phantom and T-38 Talon fly perfectly well inverted.&lt;/p&gt;&#xA;" OwnerUserId="8224" LastActivityDate="2015-04-21T18:30:15.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14295" PostTypeId="2" ParentId="14286" CreationDate="2015-04-21T18:51:32.607" Score="19" Body="&lt;p&gt;Honestly, every U.S. Air Force pilot I know, who wanted to retire to the airlines, got hired on with no problems.  The ex-Air Force pilots I know have all gotten immediately put into the big planes: A380, 747, 767, 787, etc right from the start.  This is because the airlines know that an ex-military pilot has had some of the best training and experience in high pressure situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, in the USA it is very hard to become an Air Force pilot.  You have to contract with the Air Force before they even let you know if you can go to pilot training.  That means, if you don't make the cutoff for pilot training, you have to spend at least 4 years in the Air Force.  If you do make it through Air Force pilot training you have to contract for 10 years after you finish flight school, which means about 12 years from your date of commissioning.  This will take a good 16+ years out of your life, including the time spent in college.  However, you will progress from your first flight all the way to potentially flying F-22s in under two years - a rate of progressing you won't see anywhere else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is, if you don't want to join the military then you shouldn't.  By joining the military you are expected to give your life for people you may not know, or even care about.  That aside, there's no point in spending a minimum of 16 years doing something you don't like, or fighting for a cause you don't support just to become an airline pilot.  If you can find a good airline cadet program, or scholarship, you can become a great airline pilot, it will just take a longer time to progress from one aircraft to another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just a little tangent.  That being said, I'm currently an AFROTC cadet, and I had no military background.  I love AFROTC, the US Air Force, and the USA.  I'm currently applying for a pilot slot in the U.S. Air Force, but if I don't make it I would be vary happy taking other jobs, too.  The key is to have small, achievable goals that you can take one step at a time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wish you the best of luck.&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="700" LastEditDate="2015-04-21T20:20:09.680" LastActivityDate="2015-04-21T20:20:09.680" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14296" PostTypeId="1" AcceptedAnswerId="14299" CreationDate="2015-04-21T19:02:10.207" Score="11" ViewCount="2305" Body="&lt;p&gt;Suppose that a first officer were left-handed and a captain were right-handed. Both are NOT ambidextrous. Even after training, what if their weaker hands' control and  &lt;a href=&quot;http://en.wikipedia.org/wiki/Ambidexterity#Medicine_and_surgery&quot; rel=&quot;nofollow noreferrer&quot;&gt;degree of versatility&lt;/a&gt;&lt;br&gt;&#xA;remain worse than their dominant hands'? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, in commercial (and not just &lt;a href=&quot;https://aviation.stackexchange.com/q/8786/128&quot;&gt;military&lt;/a&gt;) cockpits, joysticks (on the side) must be grasped with only one hand. But does this fact presuppose or require perfect ambidexterity?&lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-09T15:42:05.983" Title="Are there risks if the side joystick must be handled with a pilot's weaker hand?" Tags="&lt;commercial-aviation&gt;&lt;flight-controls&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14297" PostTypeId="1" CreationDate="2015-04-21T19:18:41.607" Score="2" ViewCount="1485" Body="&lt;p&gt;The design of large transport aircraft is governed by EASA's CS-25 regulation and the FAA's FAR Part 25 regulation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems however that these regulations are nearly identical. It is obvious that a lot of collaboration took place between the two authorities in the creation of these standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any &lt;strong&gt;&lt;em&gt;major&lt;/em&gt;&lt;/strong&gt; differences between these standards?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="2355" LastEditDate="2015-04-22T06:42:18.813" LastActivityDate="2015-04-22T06:42:18.813" Title="Difference between EASA and FAA regulations for airliners?" Tags="&lt;airliner&gt;&lt;faa&gt;&lt;regulations&gt;&lt;easa&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2015-04-22T08:48:53.767" ContentLicense="CC BY-SA 3.0" />
  <row Id="14298" PostTypeId="2" ParentId="14241" CreationDate="2015-04-21T19:29:03.923" Score="3" Body="&lt;p&gt;I'm not aware of any FAA-approved (or FAA-accepted) products for on-engine fuel injector cleaning. If your injectors are blocking due to lead deposits a tricresyl phosphate additive may help improve lead scavenging and prevent the problem, but it's probably not going to clean a clogged injector. (TCP is also pretty nasty stuff – leaning your engine more aggressively can often accomplish the same thing without the chemicals.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Frankly 100LL is a pretty darn good solvent: it even dissolves that blue dye they put in it which nothing else ever seems to budge. If your injectors are blocked due to contamination that 100LL won't dissolve having your mechanic take them off and bench-clean them is probably a good idea (&lt;a href=&quot;https://aviation.stackexchange.com/a/14290/64&quot;&gt;as Thomas pointed out&lt;/a&gt; this isn't rocket surgery - any competent mechanic should be able to do it without damaging anything). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as other &quot;pour it into the gas&quot; cleaning additive, as with many things &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC-20-24D.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;There's an Advisory Circular that covers this (AC 20-24D)&lt;/a&gt; - at least to some extent: That Advisory Circular deals with fuel specifications for type certification of aircraft/engines/APUs, but it contains this interesting nugget:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Fuel additives that are incorporated into ASTM, governmental or military specification, or other industry-based consensus organization specification, are considered to be identified in sufficient detail to be accepted by the FAA under existing operating limitations on TCs, amended TCs, STCs, or ASTCs, provided there are no changes to those operating limitations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you can show that the injector-cleaner chemical you want to use is an approved additive according to ASTM D910 (the standard that governs 100LL avgas), your use of the additive is in accordance with the specification (&quot;not more than X% or Yppm&quot;), and the additive is not contraindicated by the manufacturer (of the engine, airframe, or any components) you should theoretically be OK to use it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigating that legal morass is something you probably don't want to do though: The risks of getting it wrong are not just paperwork-related: some additives can damage your fuel system, or even lead to an engine failure.&lt;br&gt;&#xA;A bench cleaning of your injectors is probably the easier and safer option.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-04-21T19:29:03.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14299" PostTypeId="2" ParentId="14296" CreationDate="2015-04-21T19:41:39.987" Score="22" Body="&lt;p&gt;I can't speak for all pilots everywhere, but I've flown both sticks and yokes from both the right and left seat (as well as the front and the back seat in tandem aircraft) and found the adjustment process between switching from right to left hand to be very quick. I found getting used to sight picture differences to be a much bigger challenge and, like many others before me, sideloaded my first few landings (along with climbing/descending during turns) until I got the hang of it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other pilots I've spoken to about this have expressed the same feelings; there is a learning curve, but it is by no means insurmountable. At any rate, flying is far more of a mental activity, with masterful physical coordination being surprsingly far down the list of innate qualities a pilot needs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no, I am not nearly ambidextrous; in fact, my coordination abilities with my non-dominant hand are hilariously poor, as anyone who's ever watched my try to toss a tennis ball during a serve can attest.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-04-21T19:41:39.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14300" PostTypeId="2" ParentId="14296" CreationDate="2015-04-21T20:22:15.470" Score="12" Body="&lt;p&gt;No, flying with your non-dominant hand is not really an issue at all. In fact, &lt;strong&gt;most&lt;/strong&gt; pilots learn to fly with their non-dominant hand, even in aircraft with traditional yokes. This is because most airplanes are designed to be flown from the left seat and most people are right-handed. When in the left seat, you fly with your left hand on the yoke and your right on the power (or other controls, as necessary.) When in the right seat, you do the opposite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the amount of force is concerned, for larger aircraft, the force you have to apply to the stick is created more or less artificially (or, at least, it's mechanically scaled down, such as with pneumatics/hydraulics.) In newer aircraft with electronic controls, the resistance force to the pilots' input is created entirely artificially. If the controls were linked directly to the yoke in a large/fast aircraft (think a jet airliner,) it would be physically impossible to manipulate them by hand, due to the forces being applied to the control surfaces by the wind. Small aircraft, however, do often have direct linkages from the controls to the control surfaces, but, even so, it's very normal to fly them with your non-dominant hand, even for pilots who have never flown before.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-12-09T15:42:05.983" LastActivityDate="2015-12-09T15:42:05.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14301" PostTypeId="2" ParentId="14223" CreationDate="2015-04-21T21:39:14.583" Score="4" Body="&lt;p&gt;Only a mechanical inspection is likely to give you a definitive answer for why the AI tumbled, but typically it'll happen for one of two reasons: either the vacuum pump has decided to take a break, in which case the AI gyros slow down and will eventually no longer hold the instrument up, or you've exceeded the instrument's pitch and/or bank limits and caused it to tumble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the former, there's not much you can do in a stock -172 about that. Section 3 in the PIM just tells to verify that the vacuum pump is operating with normal parameters (green arc is 4.5-5.5 in.hg). I've seen PA-28Rs with electric vacuum pumps that served as standbys to the engine-driven ones, but never seen one in a -172, not even as an STC mod. You could always try increasing the throttle; pumps in older aircraft will sometimes fail to perform as expected at lower throttle settings, but there's no guarantee there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The latter case can happen during maneuvering flight if you exceed +/-30 degrees of pitch and 60 degrees of bank on a non-acrobatic AI. This can inadvertently happen when certain training maneuvers such as power-on or cross-controlled stalls are performed... enthusiastically. I've also seen tumbling occur during spin training. And then there was the Husky we used for banner-towing and which was pitched to 45 degrees on a regular basis during banner picks (waivers are wonderful things). The AI tumbled so regularly, the owner gave up on having mechanics reset it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But yea, should this happen to you again, run any checklists that might exist on the topic (either directly concerned with the AI or with the vacuum pump system), and switch to partial panel ops if necessary.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-04-22T00:25:57.057" LastActivityDate="2015-04-22T00:25:57.057" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14302" PostTypeId="2" ParentId="14275" CreationDate="2015-04-21T22:12:16.950" Score="2" Body="&lt;p&gt;As far as searching for a school, use on line resources such as the &lt;a href=&quot;http://www.aopa.org&quot; rel=&quot;nofollow&quot;&gt;AOPA&lt;/a&gt;, that's the Aircraft Owners and Pilots Association, and search for instructors. The school is one thing, but the instructors can sap your money and time without moving you forward. About the only place you can count on for weather is California. Now you have very high fuel prices as compared to the rest of the country which translates into high hourly rates for the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have the resources buy a Cessna 172 and use that for training. Many schools charge a nominal fee for the instructor (\$50/hour at Easterwood Airport in College Station, Texas) when you use your own airplane. &#xA;You can purchase a C172 for less than $40000. The cost per hour goes way down. When you get your license sell your plane and move to whatever you want. If you get one that is IFR certified you can use it for your IFR rating after you get your PPL. Some schools will lease your airplane for training others. There are many instructors NOT associated with schools which you may be able to work out a deal with. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check into Flying clubs. The Bay Area Aero Club in Pearland has great rates on airplanes. They also have a long list of &quot;Approved&quot; instructors which you contract with privately. There are hundreds of flying clubs like it in the US. You can also search for clubs on AOPA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Three months is not out of the question. There are flying schools advertising in the Flying magazine all the time which guarantee passing the written test within a week. Time and money. That's all it takes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should be able to solo within 10 hours of flight time. If you have a good instructor you will be more than ready. The cost of the Practical Exam by a FAA Approved Examiner can be between \$400 and \$500. The practical Exam can be taken free at an FAA field office. There are very few of those. If memory serves there are seven regional offices. That's why they have approved examiners. My examiner cost me $500. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck. Happy flying!&lt;/p&gt;&#xA;" OwnerUserId="8228" LastEditorUserId="1696" LastEditDate="2015-04-21T22:23:23.563" LastActivityDate="2015-04-21T22:23:23.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14304" PostTypeId="2" ParentId="8865" CreationDate="2015-04-22T02:36:00.620" Score="2" Body="&lt;p&gt;Previous answers highlight two separate issues: effects on stability and effects on control power. Its difficult to predict control power changes in the context of your question - is it an all moving stabiliser or is it an elevator (how is the configuration of the elevator changed?). If we look at the effect of increasing horizontal area when a perturbation occurs without motivator (control surface) movement, thus isolating control power changes if any, and assuming moment of inertia isn't changed in the pitch axis (which it probably will with a larger tail), then the dynamic and static stability of the aircraft will change. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming a statically stable aircraft: Dynamically, the natural frequency of the aircraft should increase. Statically, assuming the motivator generates the same lift force for a given deflection, then more control surface movement will be required to achieve the same alpha. Ultimately, the control power left will be reduced as more power is needed to counter increased stability. Hence as mentioned, the aircraft CoG working range will be reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;WRT control forces and what is 'apparent' to the pilot, this will depend on the flight control system employed. For reversible controls, conventionally stronger stick forces and larger displacement may occur (not guaranteed), however non-reversible systems with complex computer arrangements may manifest as something completely different. A moot point given we're in a completely hypothetical question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we talk about the 'effects' of changing area as opposed to 'advantages and disadvantages'; the aircraft design is tailored to achieve the intended application. &lt;/p&gt;&#xA;" OwnerUserId="8030" LastEditorUserId="8030" LastEditDate="2015-04-22T09:57:49.653" LastActivityDate="2015-04-22T09:57:49.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14305" PostTypeId="1" CreationDate="2015-04-22T02:53:11.620" Score="15" ViewCount="11215" Body="&lt;p&gt;Roskam's book on preliminary design gives a value of 0.7 for &quot;homebuilt&quot; aircraft and 0.8 for general aviation. What explains this difference in propeller efficiency? The content of Roskam's book is fantastic but some of the constants that he gives may be a bit dated as was the case for specific fuel consumption which was given as 0.7 for homebuilt aircraft when a modern engine like the Rotax 912UL has a sfc of 0.47.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a search of Wikipedia, it is written that modern propellers can have an efficiency of 0.9.&lt;/p&gt;&#xA;" OwnerUserId="3806" LastEditorUserId="15311" LastEditDate="2017-12-08T17:59:56.097" LastActivityDate="2018-12-16T13:07:12.693" Title="What is the propeller efficiency, $μ_p$, of modern propellers for light sport aircraft?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;&lt;efficiency&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14306" PostTypeId="2" ParentId="10113" CreationDate="2015-04-22T02:58:15.573" Score="-1" Body="&lt;p&gt;I suspect cockpits for complex aircraft like airliners are improving with regards to human factors due to glass cockpits which help to group information most important to the pilot in one place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just compare pictures of the 707 and 787 cockpits. Glass avionics make a huge difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regards to specific avionics companies, I imagine they do have consultants when designing the interface. When it comes to avionics, I'm quie a fan of Garmin. All their devices from avionics to bike GPSs are well designed and intuitive to use. And given how Garmin releases products besides avionics to the general public, I'm sure they know thing of two about good interface design.&lt;/p&gt;&#xA;" OwnerUserId="3806" LastActivityDate="2015-04-22T02:58:15.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14307" PostTypeId="2" ParentId="14296" CreationDate="2015-04-22T03:05:14.243" Score="6" Body="&lt;p&gt;Can you drive a car with either hand on the steering wheel at a time? I know I can. I can also hold a hold with either hand and control the plane without any noticeable differences. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think hand dominance only comes into play when it comes to more precision, dexterous things like writing. Flying, however, is done with feel for the most part so as long as you know how to fly with the forces felt on the hand from the controls, there shouldn't be any problem using either hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another analogy is with bicycles. I noticed some people can't ride with just one hand on the handlebars because they end up pushing the side of the handle bars they are holding and thus causing the bike to turn. Usually, such people can't ride with one hand with either hand. Why? Controlling a bike isn't exactly a precision thing where precise angles are achieved. Rather, its done by feel so if you can ride bike with one hand, you can do so with the other.&lt;/p&gt;&#xA;" OwnerUserId="3806" LastActivityDate="2015-04-22T03:05:14.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14308" PostTypeId="2" ParentId="13728" CreationDate="2015-04-22T03:09:56.580" Score="0" Body="&lt;p&gt;Fly-by-wire control systems may be quadruplexed such that there are 4 channels. This is all a part of the redundancy that is built into aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, take a look at this article about the A380 and redundancy.&#xA;&lt;a href=&quot;http://www.roger-wilco.net/would-i-fly-on-an-airbus-a380/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.roger-wilco.net/would-i-fly-on-an-airbus-a380/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A380 redundancy&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VxzpI.jpg&quot; alt=&quot;A380 redundancy&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3806" LastEditorUserId="8282" LastEditDate="2019-01-16T15:18:58.390" LastActivityDate="2019-01-16T15:18:58.390" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="14309" PostTypeId="2" ParentId="14275" CreationDate="2015-04-22T04:31:02.390" Score="3" Body="&lt;p&gt;Regarding possibility to do it in 2-3 months time, yes a PPL is quite possible, but a Ground study before even the course starts will allow a much better experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm an aerospace engineer, and had flown flight simulators a lot, before joining the PPL course. In my experience, ground instructions were more about chatting with the instructor on ideas, techniques, and general information and experience. These side-notes are important and not all can be found on the books.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a tentative schedule of 2-3 flights per week; &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;until the solo flight, the flight times would be 1 or two hours each. Solo flight could be around the 10th hour, depending partly on your body skills and partly on knowledge of rules and procedures, so it would possibly take two weeks to fly solo. &lt;/li&gt;&#xA;&lt;li&gt;And then it could be 2-3 hours or longer flight each, where you practice more on landings, navigation, emergencies, and weather. Before and after each flight is the time where you enjoy as much as the flight itself, thanks to the fellow students and other instructors. You could assume that this would take 3 hours on average and if you have 40 hours, you would need 13 flights, which could practically occur in 5-6 weeks.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Assuming all goes well, 2 + 6 weeks = 8 weeks seems to be the normal paced course for flight. Ground courses take some serious extra time but depends more on personal literacy and capability to pass the tests, and could even be handled beforehand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I attended the PPL course in Ankara, and the theme was just great.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-04-22T04:31:02.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14310" PostTypeId="1" AcceptedAnswerId="14316" CreationDate="2015-04-22T06:10:43.737" Score="6" ViewCount="522" Body="&lt;p&gt;I have read on &lt;a href=&quot;http://crownheights.info/chabad-news/480381/lubavitcher-woman-saves-entire-airplane/&quot; rel=&quot;nofollow&quot;&gt;a newspage&lt;/a&gt; that a passenger found an engine problem on the B767 before takeoff and requested staff to check it, while the airport claims the decision was made by the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering: Who has the right to do such decision. Will the engineers check the engine just because of a passenger's complaint?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-04-22T07:17:53.647" LastActivityDate="2015-04-23T03:10:27.310" Title="Who can request a check on an engine before boarding/takeoff?" Tags="&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14311" PostTypeId="1" AcceptedAnswerId="14313" CreationDate="2015-04-22T07:07:05.143" Score="3" ViewCount="1216" Body="&lt;p&gt;Will the Light Aircraft Pilot License (LAPL) or Private Pilot License (PPL) be enough to to be able to fly to other countries outside Europe?&lt;/p&gt;&#xA;" OwnerUserId="2150" LastEditorUserId="572" LastEditDate="2015-04-22T07:31:32.817" LastActivityDate="2015-04-22T07:31:32.817" Title="Can I use a LAPL/PPL issued by the UK CAA to fly outside Europe?" Tags="&lt;ppl&gt;&lt;caa-uk-regulations&gt;&lt;lapl&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14312" PostTypeId="2" ParentId="14275" CreationDate="2015-04-22T07:18:17.127" Score="4" Body="&lt;p&gt;A few comments:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The older you are the longer it takes. A generalisation yes, but I've been teaching people to fly for a few years and like it or not the spotty teenager wins every time over the old and wise!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flights of more than about an hour or an hour-and-a-half become counter-productive. Lots of short flights are far better than long sessions. Your mind stops absorbing stuff as effectively after the first hour. If you have 2 or 3 hours booked then land, have a coffee, debrief ( even to yourself ) the past hour and start again. Apart from Navigation exercises a 3 hour flight is just a jolly for the instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly with a purpose. decide what you want to do in each session, be honest and practice the bits you are not good at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you cram a licence understand that the learning curve after you get the ticket remains high. You learn more in the first 100 PIC hours than you ever thought possible!&lt;/p&gt;&#xA;" OwnerUserId="1304" LastActivityDate="2015-04-22T07:18:17.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14313" PostTypeId="2" ParentId="14311" CreationDate="2015-04-22T07:23:44.100" Score="3" Body="&lt;p&gt;The EASA issued LAPL(A) is limited to 2to MTOM, 3 passengers max and only valid in European countries. A PPL(A) issued by an EASA country does not have these restrictions, but can be subject to local restrictions in the non-European country you want to flyin, e.g. you cannot use the EASA PPL(A) to fly in the US without further paperwork.&lt;/p&gt;&#xA;&lt;p&gt;For more information, see the &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=2701&amp;amp;pagetype=90&amp;amp;pageid=15222&quot; rel=&quot;nofollow noreferrer&quot;&gt;UK CAA's page on the LAPL&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Your LAPL(A) is a lifetime licence that contains SEP(land) and/or TMG privileges restricted to non-complex EASA aeroplanes with a maximum take off mass of 2 metric tonnes and a maximum of four people on board.&lt;/p&gt;&#xA;&lt;p&gt;You can fly more complex aeroplanes within the privileges if you have 'differences training' signed off in your log book by a suitable instructor. The LAPL is also valid on non-EASA UK registered aircraft in the UK.&lt;/p&gt;&#xA;&lt;p&gt;The LAPL requires an in-date EASA Part-Med Medical Certificate, at LAPL level, but Class One or Class Two certificates can also be used. A valid JAA Class One or Two medical certificate is also acceptable. But you cannot use your LAPL with an NPPL medical declaration.&lt;/p&gt;&#xA;&lt;p&gt;The SEP(land) or TMG endorsement on this type of licence is not issued as a rating. So there is no rating expiry date. Instead you must follow self-validity checks on your own flying history for the past 2 years to ensure currency on the day of your planned flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Further Reading from the UK CAA:&lt;br /&gt;&#xA;&lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=2685&amp;amp;pagetype=65&amp;amp;appid=54&amp;amp;mode=summary&amp;amp;appprocsum=13&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA Light Aircraft Pilot License Aeroplane - LAPL(A)&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=2685&amp;amp;pagetype=65&amp;amp;appid=54&amp;amp;mode=summary&amp;amp;appprocsum=8&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA Private Pilots Licence Aeroplane - PPL(A)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-22T07:29:35.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14314" PostTypeId="5" CreationDate="2015-04-22T07:32:48.263" Score="0" Body="" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-04-22T07:32:48.263" LastActivityDate="2015-04-22T07:32:48.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14315" PostTypeId="4" CreationDate="2015-04-22T07:32:48.263" Score="0" Body="The Light Aircraft Pilot License (LAPL) is an EASA-issued license for aircraft limited to 2to MTOW, 4 occupants on board and limited to flights within Europe." OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-04-22T07:32:48.263" LastActivityDate="2015-04-22T07:32:48.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14316" PostTypeId="2" ParentId="14310" CreationDate="2015-04-22T11:03:11.053" Score="3" Body="&lt;p&gt;I guess this will vary from airport and scenarios. Say if you are in a small Cessna on a little grass-strip: They will most likely always listen to you. However, In a passenger jet, on a busy airport: Things fast get a little more complicated. It is very expensive for an airliner to hold a plane, and even more to ground it. And it affects more people than it would with the Cessna scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you tell, say the flight attendant while the plane is rolling down the taxiway that you hear abnormal sounds: They will likely misinterpret you as nervous and will most likely ignore it. But if you can somehow socially convince them: It is still the captain that makes the end decision about turning around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if this has actually happened before other than in the article mentioned in the question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If there is something wrong about the plane: The captain will likely know well before you do. The engines have so many sensors and fail-safes that the captain will likely have the fault displayed in the cockpit before you even notice something unusual, and he will probably make the decision before you even reach a flight attendant.&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="693" LastEditDate="2015-04-22T11:16:56.337" LastActivityDate="2015-04-22T11:16:56.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14317" PostTypeId="1" AcceptedAnswerId="14326" CreationDate="2015-04-22T11:51:21.450" Score="10" ViewCount="1191" Body="&lt;p&gt;Is there any new cockpit that uses voice commands (think for example Siri from the new iphones) that can identify the voice of the pilot and help him/her to fly?&lt;/p&gt;&#xA;" OwnerUserId="8094" LastEditorUserId="1467" LastEditDate="2015-04-22T12:32:56.447" LastActivityDate="2015-04-27T20:27:00.843" Title="Is there a cockpit which can recognize the voice of the pilot and help him/her to fly?" Tags="&lt;autopilot&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14318" PostTypeId="2" ParentId="14317" CreationDate="2015-04-22T12:38:17.797" Score="13" Body="&lt;p&gt;No, voice recognition is currently not used in aircraft as it would have to be built into the aircraft to pass certification for the aircraft and with rotating crews on aircraft, the voice recognition would need to be able to work with too many different voice types: high pitch, low pitch, male, female, accents, dialects and many more factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Voice recognition works because it learns from the user over time, something that is not possible in a cockpit environment with crew resource management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a &lt;a href=&quot;https://aerospace.honeywell.com/news/honeywell-testing-in-flight-voice-recognition-for-future-cockpits&quot;&gt;prototype in development by Honeywell&lt;/a&gt; at the moment, but it's in early stages of development. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related reading:&#xA;&lt;a href=&quot;http://www.adacel.com/press/innews/8_25_06_Benefits_Speech_Recognition_Enabled_Cockpit.pdf&quot;&gt;The benefits of a Speech Recognition enabled cockpit by Adacel&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-04-22T12:38:17.797" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14319" PostTypeId="2" ParentId="14310" CreationDate="2015-04-22T13:28:44.740" Score="3" Body="&lt;p&gt;Some times the cases are black and white like &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2543954/Dreamliner-grounded-passengers-film-fuel-pouring-wing-Bangkok.html&quot; rel=&quot;nofollow&quot;&gt;this one&lt;/a&gt; where its very obvious that something is wrong (fuel is pouring out). But this brings up the question of &quot;how do you know something is wrong with the engine?&quot;. I will admit that I know a fair amount about airplanes and avionics but I would not be able to identify an engine issue (on a jet) shy of something obviously visibly wrong. Then, as mentioned you would have to convince the crew that you knew what you were talking about. If we think about the scenario its clear that there are 2 pilots on board (who are presumably more qualified on the matter than you). 2 Pilots who should have done preflight checks and an airline that should be monitoring the use and time on its engines. So who are you to say there is anything wrong. That being said if you think there may be an issue(and have some decent grounds to think so) you should always say something as its better safe than sorry. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-22T13:28:44.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14320" PostTypeId="2" ParentId="14275" CreationDate="2015-04-22T13:36:04.367" Score="2" Body="&lt;p&gt;In Argentina we have a 40 hs minimum to take the exam. As I learned in one of the busiest airports near Buenos Aires, it took me a little more -56 hs- because it included much radio communication and control procedures that other flight schools in other cities don't need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As many other pilots, the experience with MS Flight Simulator really helped. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking back, I feel you can learn to fly in the first two hours or so. Then you happily spent your money learning how to land in one piece and walking... Don't limit yourself, take your time and be safe!&lt;/p&gt;&#xA;" OwnerUserId="3442" LastActivityDate="2015-04-22T13:36:04.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14321" PostTypeId="1" AcceptedAnswerId="14322" CreationDate="2015-04-22T13:50:20.873" Score="0" ViewCount="422" Body="&lt;p&gt;International numbers state that planes downed by pilot or co-pilot due to suicide are a rare but still possible occurrence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the United States such a safety procedure is standard (as of 9/11 - if I remember correctly). Why didn't the EASA think of that earlier?&lt;/p&gt;&#xA;" OwnerUserId="8232" LastEditorUserId="65" LastEditDate="2015-04-22T13:57:06.370" LastActivityDate="2015-04-22T14:02:16.643" Title="Why didn't the EASA enforce the 2 man cockpit rule BEFORE the Gemanwings accident?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;cockpit&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-04-22T14:22:39.143" ContentLicense="CC BY-SA 3.0" />
  <row Id="14322" PostTypeId="2" ParentId="14321" CreationDate="2015-04-22T13:54:33.433" Score="4" Body="&lt;p&gt;Graveyard evolution; new advances are only pushed through when the existing situation is provably not safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation history is rife with examples of safety measure being taken after an incident of accident that could have been prevented by that measure.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-04-22T13:54:33.433" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="14324" PostTypeId="2" ParentId="14321" CreationDate="2015-04-22T14:02:16.643" Score="7" Body="&lt;p&gt;Because aviation procedures and rules develop from historical occurances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, the actual occurance and the resulting change in procedures do not have anything in common or are not related, e.g. some will argue that the two-man rule would not have prevented 9/11. It is also being discussed that the two man rule would only have had a psychological effect to deter the pilot/copilot from deliberately crashing the plane (as in the Germanwings crash), some will argue that a pilot or co-pilot intent to deliberately crash the airplane will not be deterred by a flight attendant in the cockpit, who due to lack of flight education would not be able to counter the pilot's/copilot's input in the FMC/AP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpit door measures to deny unauthorized access to the cockpit were implemented because the threat was assumed to come from outside the cockpit. You cannot implement measures that will work against everything and every threat, internal or external. Hence why EASA (and this is only speculative, because we can't know for sure) did not implement a two-man rule and currently has not implemented one, the two-man rule is a airline SOP issue at the moment.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-04-22T14:02:16.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14325" PostTypeId="1" CreationDate="2015-04-22T18:01:36.770" Score="1" ViewCount="63" Body="&lt;p&gt;As a passenger on a regularly scheduled flight, how can I determine what areas my flight is likely to overfly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that inclement weather, other aircraft, and other outside influences (both somewhat predictable and completely unpredictable) can and will modify the planned route to some extent, which would be bonus information, but not necessary.&lt;/p&gt;&#xA;" OwnerUserId="8233" LastEditorUserId="5517" LastEditDate="2015-04-22T18:04:50.993" LastActivityDate="2015-04-22T18:04:50.993" Title="How do I determine the probable path of a future flight?" Tags="&lt;commercial-aviation&gt;&lt;passenger&gt;&lt;navigation&gt;&lt;flight-planning&gt;&lt;flight-path&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-04-22T18:50:25.687" ContentLicense="CC BY-SA 3.0" />
  <row Id="14326" PostTypeId="2" ParentId="14317" CreationDate="2015-04-22T21:38:42.837" Score="12" Body="&lt;p&gt;Yes...kind-of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was &lt;a href=&quot;http://www.voiceflight.com&quot;&gt;a product by a company called VoiceFlight&lt;/a&gt; which would allow you to program Garmin GPS systems (GNS 430/530), which was FAA-approved by STC for a good number of light General Aviation aircraft.&lt;br&gt;&#xA;While it was not capable of flying the plane by voice instruction it could be used to program a route into the GPS, which a coupled autopilot would then be able to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The VoiceFlight product has been discontinued as competition from the newer GTN 650/750 (which require less knob-twiddling to program a route) and other technologies like &lt;a href=&quot;http://www.connectedpanel.com&quot;&gt;Connected Panel&lt;/a&gt; ate into the company's business to the point where it was no longer viable to remain in business, but the core idea of voice technology in the cockpit has been proven possible (and according folks who tried it, even practical). It may make another appearance some day.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-04-22T21:38:42.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14327" PostTypeId="1" AcceptedAnswerId="14331" CreationDate="2015-04-23T00:11:21.437" Score="12" ViewCount="7403" Body="&lt;p&gt;The planes landing at Sydney Airport have what looks to be sheets of steam pouring off the wings. Larger planes have multiple contrails while smaller regional planes only have these sheets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the first sunny day after a large storm. There are patches of dark cloud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://youtu.be/dBjTnS-X8ik&quot;&gt;the link&lt;/a&gt; posted by fooot, I've learned that it's condensation, but what is the mechanism by which it forms?  The video shows planes in poor weather, but visibility here is excellent, with 20% cloud coverage.&lt;/p&gt;&#xA;" OwnerUserId="8235" LastEditorUserId="167" LastEditDate="2015-04-23T03:50:27.453" LastActivityDate="2015-05-01T17:22:02.293" Title="What is the mechanism by which condensation forms above wings?" Tags="&lt;wing&gt;&lt;contrails&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14328" PostTypeId="2" ParentId="14310" CreationDate="2015-04-23T03:10:27.310" Score="2" Body="&lt;p&gt;The pilot in command always has the final decision. Of course, an unruly passenger can always force a return to the gate. This does not mean, however, that the plane will be checked over. In general, the PIC will be glad to be alerted to any anomaly, but a passenger has no authority to demand a plane be mechanically examined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to a &lt;a href=&quot;http://www.israelnationalnews.com/News/News.aspx/194188&quot; rel=&quot;nofollow&quot;&gt;followup article&lt;/a&gt;, the claims that the passenger first noticed the problem were wildly exaggerated, and, in fact, according to TransAero the crew was already working on the problem when the women complained and her actions made no difference to the process. Yet another shaggy dog story?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-04-23T03:10:27.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14329" PostTypeId="1" AcceptedAnswerId="14330" CreationDate="2015-04-23T03:18:12.667" Score="7" ViewCount="32033" Body="&lt;p&gt;Fighter pilots are always portrayed as young, fit men (and woman), in their 20s and 30s - and most of the F16 pilots I know are that age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, today someone, who is over 50 years old, mentioned that he was asked to be an F22 pilot.  His background is astonishing, flying in multiple &quot;wars,&quot; and he was even the commander of the Thunderbirds in F-16s for a while.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though this man clearly has the background of the stereotypical F22 pilot, would age be a problem?  Wouldn't someone whose body could take more abuse be better suited for that type of assignment?&lt;/p&gt;&#xA;" OwnerUserId="700" LastActivityDate="2018-05-05T18:15:04.310" Title="What is the &quot;optimal&quot; age of a fighter pilot?" Tags="&lt;us-air-force&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14330" PostTypeId="2" ParentId="14329" CreationDate="2015-04-23T03:45:23.447" Score="8" Body="&lt;p&gt;It depends on what you mean by &quot;optimal&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a dogfight, the optimal age is probably 30. At this age a person has lots of experience, but still maintains their full mental agility, ability to calculate and energy. In a dogfight your ability to think fast and calculate your next move is the critical factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For combat missions, however, 40-45 may be more optimal, because experience, judgement and knowledge becomes more important. Knowing when to attack, how to attack, how to make your approach, how to do your mission setup, and many other things become the product of long experience. For complicated missions in enemy territory, it is better to have someone with long experience, rather than a young hotshot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once a person hits about 60-65 years in age, their mental ability to calculate declines significantly. Nevertheless, experience can make up for it in some instances. For example, at age 63 &lt;a href=&quot;https://en.wikipedia.org/wiki/Vasily_Smyslov&quot; rel=&quot;noreferrer&quot;&gt;Vassily Smyslov&lt;/a&gt; was a candidate for the world chess championship, an amazing accomplishment for a person of that age. Emanuel Lasker took 3rd place at Moscow 1935, a premier chess tournament, at the age of 66, which was practically a miracle. These are exceptions, however. In general, once a person gets into their 60s, their mental ability deteriorates. Therefore, the age 50-55 can be considered the maximum age at which experience and judgement can be used effectively in high speed combat situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Complex Mission Role&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To investigate my basic assertion that optimal age for a combat mission (not air supremacy) pilot is 40-45 I investigated pilot astronauts. Since astronauts are selected from large numbers of candidates and have short careers typically, it is a safe assumption that their average age is what NASA considers to be ideal. According to &lt;a href=&quot;http://hdl.handle.net/2060/19930020135&quot; rel=&quot;noreferrer&quot;&gt;NASA Technical Report 1304&lt;/a&gt; the mean age for all selected pilot candidates is 39.90 years old. If we assume a pilot has a 5-year career, then my guess for optimal age matches perfectly with NASA's selection choices. This may be considered strong evidence that for a pilot executing complex missions, the optimal age range is, indeed, 40 to 45 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Air Supremacy Role (&quot;dog fighting&quot;)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To determine the optimal age for air supremacy (&quot;dog fighting&quot;), if we had access to the USAF's (or other country's) exercise data over time, we might get an idea since we could calculate an ELO rating for each combatant and identify to the top exercise fighters of all time. Unfortunately this kind of data is not released as far as I know, probably because the armed services do like naming or identifying particular soldiers. I do strongly suspect, though, that if such a study was done it would show the &quot;best in the world&quot; air supremacy pilots would be clustered around the age of 30. To check this, I tried summarizing statistics from WW2 German fighter pilots. Using birth data on 470 German aces I generated the following plot:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NHyaK.png&quot; alt=&quot;fighter pilot stats&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this chart, the bar chart is the total number of aces grouped by date of birth. The blue dots are the average number of victories for that birth year group. What this chart seems to show is that performance is remarkably consistent between the ages of 18 and 32, with a slight advantage to the younger pilots, but then declines significantly. The 1922 group was significantly skewed by &lt;a href=&quot;http://en.wikipedia.org/wiki/Erich_Hartmann&quot; rel=&quot;noreferrer&quot;&gt;Erich Hartmann&lt;/a&gt;. If we eliminate him as an outlier, the top group is the class of 1920 which would have been between the ages of 19 and 25 during the war. This seems to show my original guess was wrong, and that dogfighting is dependent more on quick reflexes and fast thinking than on experience, which hands the edge to the young.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-04-24T12:31:06.940" LastActivityDate="2015-04-24T12:31:06.940" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="14331" PostTypeId="2" ParentId="14327" CreationDate="2015-04-23T04:55:28.827" Score="8" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5230&quot;&gt;We know&lt;/a&gt; that the pressure decreases over the wing. We can also assume that a particle of air travelling above a wing does it  so fast that does not have the time to exchange energy with the sorrounding ones (called &lt;a href=&quot;http://en.wikipedia.org/wiki/Adiabatic_process&quot; rel=&quot;nofollow noreferrer&quot;&gt;adiabatic process&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can now look at a pressure/volume diagram for an adiabatic process that goes from &quot;high&quot; pressure (the free undisturbed air in front of the aircraft) to low pressure (the air on top of the wing):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1r3kL.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;image &lt;a href=&quot;http://whs.wsd.wednet.edu/faculty/busse/mathhomepage/busseclasses/apphysics/studyguides/chapter121314/graphic/Fig-14-12a.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt; (currently unreachable)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you see from the diagram, if you move along the Adiabat line from the top to the bottom, the temperature drops. If the air has already a temperature near the water condensation one and a high enough humidity, it will condense.&#xA;From the Wikipedia article linked before:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Adiabatic cooling&lt;/strong&gt; occurs when the pressure on an adiabatically isolated system is decreased, allowing it to expand, thus causing it to do work on its surroundings. &lt;em&gt;When the pressure applied on a parcel of air is reduced&lt;/em&gt;, the air in the parcel is allowed to expand; as the volume increases, the temperature falls as internal energy decreases.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-04-23T12:34:02.760" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14333" PostTypeId="2" ParentId="14261" CreationDate="2015-04-23T09:05:59.207" Score="5" Body="&lt;p&gt;Usually the Engines on the same plane are of the same model (or type). As mentioned in an answer earlier the rotation direction of jet turbines doesn't affect handling, however, the engines installed on either sides must have same thrust as to make the handling easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example for differing engines however is A380, where the inboard engines are equipped with thrust reverser and &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380#Engines&quot; rel=&quot;noreferrer&quot;&gt;outboard engines don't have them.&lt;/a&gt; There are several reasons for doing this, not having thrust reverser makes engine comparatively simpler to build and maintain. &lt;/p&gt;&#xA;" OwnerUserId="7863" LastEditorUserId="572" LastEditDate="2015-04-23T09:07:31.890" LastActivityDate="2015-04-23T09:07:31.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14334" PostTypeId="1" AcceptedAnswerId="14339" CreationDate="2015-04-23T13:56:48.313" Score="11" ViewCount="3035" Body="&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/questions/8339/how-are-off-wing-jet-engines-transported&quot;&gt;question&lt;/a&gt; about engine transportation made me wonder what is the size of the biggest item ever transported. Then I remembered that it should have been a space shuttle (either &lt;a href=&quot;http://www.airliners.net/photo/VKK-Buran/2396061/&amp;amp;sid=c909ba0928fded5d0a3bdb818413216c&quot; rel=&quot;nofollow noreferrer&quot;&gt;Buran&lt;/a&gt; or the &lt;a href=&quot;http://www.airliners.net/photo/NASA/Rockwell-Space-Shuttle/0293415/&amp;amp;sid=8f41d23fa040e87d85219e7d72d23821&quot; rel=&quot;nofollow noreferrer&quot;&gt;American Space Shuttle&lt;/a&gt;), but those items are no longer transported. Nowadays whole aircraft sections are transported, thanks to &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;nofollow noreferrer&quot;&gt;A300-600ST&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Dreamlifter&quot; rel=&quot;nofollow noreferrer&quot;&gt;B747LCF&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there cargo items bigger than a high by-pass ratio jet engine or an aircraft section that are transported by air today (in 2015)? How are those item handled?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2017-01-02T11:22:57.797" Title="Are there items bigger than an aircraft section transported by air today?" Tags="&lt;cargo&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14335" PostTypeId="2" ParentId="14329" CreationDate="2015-04-23T13:58:02.557" Score="12" Body="&lt;p&gt;I can't directly tell you what's &quot;optimal&quot; because I don't know what that means, but the US Air Force does provide some &lt;a href=&quot;http://www.afpc.af.mil/library/airforcepersonneldemographics.asp&quot;&gt;basic demographic information&lt;/a&gt; so we can indirectly see what they consider to be a good age mix for fighter pilots. I used their &lt;a href=&quot;http://access.afpc.af.mil/vbinDMZ/broker.exe?_program=IDEASPUB.IDEAS_default.sas&amp;amp;_service=pZ1pub1&amp;amp;_debug=0&quot;&gt;report tool&lt;/a&gt; to get data on fighter pilots&lt;sup&gt;1&lt;/sup&gt; and it shows this breakdown:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;17-24 :    43&#xA;25-34 : 1,341 &#xA;35-44 :   968 &#xA;45+   :    83&#xA;Total : 2,435&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This isn't very fine-grained, but on the other hand we can immediately see that your example of someone over 50 is really at the extreme end of the curve: only 3.4% of fighter pilots are over 45.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this only applies to the USAF and it doesn't tell us anything about other branches of the military or about what other countries do. But we can say that the USAF appears to consider 25-34 to be the 'optimal' age: 55% of their fighter pilots are in that bracket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I should add a small disclaimer that I know nothing about the military, so hopefully I didn't make any stupid mistakes in pulling or interpreting the data.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; To be specific, the search criteria I used were: Active Duty Air Force only (excludes Air National Guard, Air Force Reserve and civilians); officers only; &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Force_Specialty_Code&quot;&gt;AFSC&lt;/a&gt; 11FX specialty (fighter pilot) only. The data is from April 2015.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-23T18:29:11.447" LastActivityDate="2015-04-23T18:29:11.447" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14336" PostTypeId="2" ParentId="13066" CreationDate="2015-04-23T14:12:59.880" Score="4" Body="&lt;p&gt;Some airplanes, like the Pilatus PC-12 pictured below, have a captain's side window that can be opened during landing so that the pilot has a direct view of the runway. If the windscreen is damaged, blocked, or iced-over, the captain can fly on instruments to the airport, then land by opening and looking out the little window.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rflGN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-04-23T14:12:59.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14337" PostTypeId="2" ParentId="14329" CreationDate="2015-04-23T14:26:23.697" Score="4" Body="&lt;p&gt;In addition of &lt;a href=&quot;https://aviation.stackexchange.com/a/14335/65&quot;&gt;Pondlife's excellent answer&lt;/a&gt;, there are a few points I would like to mention.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is no specific age at which a person no longer remains a fighter pilot. It relates more to that individual's physical and mental capabilities.&lt;/li&gt;&#xA;&lt;li&gt;In air force/military, when a person reaches senior ranks, there are other responsibilities which are added.&lt;/li&gt;&#xA;&lt;li&gt;When a person is no longer a fighter pilot, it &lt;em&gt;does not&lt;/em&gt; mean that they cannot fly an F-16, F-22, or any of the airplanes they used to fly. It just means that they are not combat ready anymore. They can still teach to fly or fly at air force demonstrations etc. In fact, the air chief marshal of a country (long retired from combat flying) leads the air force squadron on their annual ceremony.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From the numbers Pondlife mentioned, it does appear that the &lt;em&gt;optimal age&lt;/em&gt; of about 95% of pilots is in fact in 25-44 range, but many are able to keep the abilities beyond that age range.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-23T14:52:05.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14338" PostTypeId="2" ParentId="14334" CreationDate="2015-04-23T16:03:51.360" Score="21" Body="&lt;p&gt;According to Wikipedia, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Antonov_An-225_Mriya&quot;&gt;An-225&lt;/a&gt; is the world's largest cargo aircraft and it's transported both the heaviest and longest items of cargo ever carried by air:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 11 August 2009, the heaviest single cargo item ever sent via air&#xA;  freight was loaded onto the Antonov 225. At 16.23 metres (53.2 ft)&#xA;  long and 4.27 metres (14.0 ft) wide, its consignment, a generator for&#xA;  a gas power plant in Armenia along with its loading frame, weighed in&#xA;  at a record 189 tonnes (417,000 lb)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;On 11 June 2010, the An-225 carried the world's longest piece of air&#xA;  cargo, when it flew two new 42-meter test wind turbine blades from&#xA;  Tianjin, China&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's also carried the &lt;a href=&quot;http://en.wikipedia.org/wiki/Buran_%28spacecraft%29&quot;&gt;Buran&lt;/a&gt; spacecraft (the 'Soviet space shuttle'), which was actually what the aircraft was originally built for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The An-225 is &lt;a href=&quot;http://www.antonov.com/aircraft/transport-aircraft/an-225-mriya&quot;&gt;still in operation&lt;/a&gt; and the operator gives some examples of large cargo that can be carried:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft has the spacious cargo compartment with length of 43.32&#xA;  m, width of 6.4 m and height of 4.4 m, that allows carrying a variety&#xA;  of cargoes inside. For instance,&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;sixteen standard aeronautical containers of UAC−10 type;&lt;/li&gt;&#xA;  &lt;li&gt;50 cars;&lt;/li&gt;&#xA;  &lt;li&gt;single piece of cargoes up to 200 t (turbines, generators, dump trucks − Belaz, Kamatsu, Euclid, etc.).&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="65" LastEditDate="2015-04-23T16:40:46.273" LastActivityDate="2015-04-23T16:40:46.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14339" PostTypeId="2" ParentId="14334" CreationDate="2015-04-23T16:52:30.553" Score="19" Body="&lt;p&gt;When you are not restricted by the size of a cargo hold, your cargo can become much bigger. See below how a &lt;a href=&quot;http://en.wikipedia.org/wiki/Mil_Mi-26&quot; rel=&quot;noreferrer&quot;&gt;Mil-26&lt;/a&gt; lifts the fuselage and wing root of a Tu-134. I have not checked whether this is a record, but I would expect that the world record will involve the Mil-26 somehow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/D2p6P.jpg&quot; alt=&quot;Mil-26 lifting a Tu-134 carcass, seen from below&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Mil-26 lifting a Tu-134 carcass, seen from below (&lt;a href=&quot;http://www.businessinsider.com/russia-mi-26-helicopter-llft-biggest-2014-5?IR=T&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-01-01T22:33:46.543" LastActivityDate="2017-01-01T22:33:46.543" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14340" PostTypeId="1" CreationDate="2015-04-23T17:00:13.483" Score="4" ViewCount="535" Body="&lt;p&gt;I own an older but still nice noise-cancelling general aviation headset from Denali, with the two-plug adapter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if I can/shall repurpose it.  For example, I now have to take a number of international flights, 14 hours as a sardine...  not fun.  Does a GA headset make for a good entertainment and silence headset?  Or, I could use the GA headset for phone calls from my Android cell phone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good idea / bad idea?&lt;/p&gt;&#xA;" OwnerUserId="8245" LastEditorUserId="97" LastEditDate="2015-05-03T00:35:27.227" LastActivityDate="2015-06-02T00:37:12.530" Title="Can a GA headset be used for listening to normal audio or with a cell phone?" Tags="&lt;passenger&gt;&lt;headset&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14341" PostTypeId="2" ParentId="14340" CreationDate="2015-04-23T19:48:33.657" Score="2" Body="&lt;p&gt;I actually know a guy that does this. He bought a nice noise canceling headset but then stopped flying and now he uses it on long flights and quite enjoys it. For what its worth noise canceling headphones have come down in price over the years and you may simply be able to sell the headset and buy a less bulky set of headphones for the money you make. But if you dont want to go through the hassle then there is nothing stopping you from using aside from having a boom mic dangling off it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth a lot of noise canceling headphones now have mic inputs as well so you can answer calls from them as well. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-04-23T20:47:45.803" LastActivityDate="2015-04-23T20:47:45.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14342" PostTypeId="1" CreationDate="2015-04-23T21:22:06.183" Score="32" ViewCount="13866" Body="&lt;p&gt;Why isn't there a protective screen with large diameter holes (approx 2') mounted in front of the jet engine intake to protect the turbine blades? This would  keep larger birds and large ground debris from getting sucked in, which can cause serious internal engine damage.&lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="15311" LastEditDate="2018-06-15T14:05:28.353" LastActivityDate="2019-03-17T14:58:35.367" Title="Would it be viable to install a screen in front of jet intakes to prevent them from sucking in birds?" Tags="&lt;turbine&gt;&lt;bird-strike&gt;&lt;foreign-object-damage&gt;" AnswerCount="5" CommentCount="9" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14343" PostTypeId="2" ParentId="14342" CreationDate="2015-04-23T21:27:09.450" Score="9" Body="&lt;p&gt;When flying any surface that is exposed to the air will generate drag. That screening, although full of holes, will create significant drag when exposed to the air that is entering in the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it will distort the air entering the engine reducing the efficiency of the engine and increasing fuel comsuption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Globally, the extra drag and the higher fuel consumption is more costly than the increase of weight needed for generating extra protection on the engine nacelle.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-04-23T21:27:09.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14344" PostTypeId="2" ParentId="14342" CreationDate="2015-04-23T23:14:56.217" Score="59" Body="&lt;p&gt;Modern high-bypass turbofan engines work by pulling in immense volumes of air and accelerating it.  A screen as proposed would make that task far more difficult, which would ruin the efficiency of the engine.  It's also pretty well unnecessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jets worldwide take plenty of birdstrikes every day.  Unless the pilots see it (hitting the windscreen will do that) or hear it (hitting something near the cockpit) or the bird goes into the engine core (which causes the smell of burned bird in the air conditioning), the chance that the crew knows about it before the next walk-around inspection is pretty slight.  The vast majority of birdstrikes are utterly inconsequential.  (Except for the bird -- ruins his day pretty thoroughly!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, there are a small number of very highly visible events where birds do disable an aircraft -- the &quot;miracle on the Hudson&quot; and the loss of an AWACS in Alaska come to mind, and there are others.  And it's possible for a birdstrike on an engine to cause significant damage IF the bird is large enough AND it goes into the core, but in the big picture, that is actually pretty uncommon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, the aircraft manufacturers and operators end up accepting the risk of a catastrophic birdstrike, because the alternative of protecting the engine as suggested is too expensive when the effects on the efficiency of the engine are considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One other point, bird flesh is pretty easy for an engine to chop up and digest.  If a big bird hits a metal shield at high speed, there would be the risk that the shield could be damaged enough that some of the metal would break apart and go into the engine as well, and THAT would cause far more damage than just the bird.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=_jfXX7qppbc&quot; rel=&quot;noreferrer&quot;&gt;Fun video of stuff being shot into an engine during testing&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="946" LastEditDate="2019-01-16T21:49:43.463" LastActivityDate="2019-01-16T21:49:43.463" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="14345" PostTypeId="1" CreationDate="2015-04-23T23:22:05.037" Score="4" ViewCount="259" Body="&lt;p&gt;I'm currently living in Boston and fly out of KBED regularly. I'm looking into making a long cross country in a Cessna 182T to the Bahamas and am planning my route. I'm IFR rated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for airports generally along the east coast (east of KATL and south of KBED) that have at least one of the following and are less than a 25 minute drive from the field: diner/restaurant with at least 3 stars on yelp, museum, historic or tourist attractions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some places that have caught my attention:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;KBID (Block Island State, RI) - Bethany's Airport Diner is on the&#xA;field and has 4 stars on yelp &lt;/li&gt;&#xA;&lt;li&gt;0B8 (Fishers Island, NY) - friend says&#xA;it's a 15 minute walk to a really nice golf club open to anyone &lt;/li&gt;&#xA;&lt;li&gt;KMYR (Myrtle Beach, SC) - there's a 100 things to do walking distance from the airport (parks, beach, restaurants, tours, etc...) &lt;/li&gt;&#xA;&lt;li&gt;KCHS or KJZI (Charleston, SC) - 20 minute drive to the historic downtown of the city&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Really appreciate your input!&lt;/p&gt;&#xA;" OwnerUserId="8139" LastEditorUserId="6919" LastEditDate="2015-04-24T00:13:33.077" LastActivityDate="2015-04-24T00:13:33.077" Title="What airports close to the east coast of the US have attractions that are easy to get to?" Tags="&lt;airport&gt;&lt;usa&gt;&lt;flight-planning&gt;&lt;flight-path&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2015-04-24T06:50:39.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="14346" PostTypeId="2" ParentId="14342" CreationDate="2015-04-24T04:42:11.707" Score="18" Body="&lt;p&gt;A few Russian/Soviet fighters had retractable FOD screens on their engine intakes (MiG-29 and Su-27 IIRC). The assumption was that they would operate from damaged runways or roads and the engines would need protection against Foreign Object Damage (FOD).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FAls1.jpg&quot; alt=&quot;MiG-29 intake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right air intake of a MiG-29 with main doors closed and louvres on the wing root opened.&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="15311" LastEditDate="2018-06-15T13:16:19.520" LastActivityDate="2018-06-15T13:16:19.520" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="14347" PostTypeId="2" ParentId="14334" CreationDate="2015-04-24T05:27:00.490" Score="9" Body="&lt;p&gt;I'm not sure if this counts since it's still in development and production, but Scaled Composites' &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_Stratolaunch&quot; rel=&quot;noreferrer&quot;&gt;Stratolaunch Carrier Aircraft&lt;/a&gt; (dubbed the &lt;em&gt;Roc&lt;/em&gt;) will almost certainly shatter any existing records for payload capacity. Its mating system is designed to hold up to 500,000 lb (230,000 kg.) Its intended payload, like that of &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_White_Knight&quot; rel=&quot;noreferrer&quot;&gt;WhiteKnight&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Scaled_Composites_White_Knight_Two&quot; rel=&quot;noreferrer&quot;&gt;WhiteKnight 2&lt;/a&gt;, is a rocket stack mounted between the twin fuselages to be air launched. At least as of December 2011, the first flight test &lt;a href=&quot;http://www.space.com/13915-paul-allen-giant-plane-stratolaunch-systems-private-space.html&quot; rel=&quot;noreferrer&quot;&gt;was indeed scheduled for 2015&lt;/a&gt;, so I guess it technically does meet the 'in 2015' criterion for this question. :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific 'item to be carried' in this case is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pegasus_II_(rocket)&quot; rel=&quot;noreferrer&quot;&gt;Pegasus II rocket stack&lt;/a&gt; with a gross weight of 465,000 lb. (211,000 kg,) &lt;a href=&quot;http://aviationweek.com/blog/stratolaunch-quietly-making-progress&quot; rel=&quot;noreferrer&quot;&gt;according to Aviation Week&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stratolaunch carrier aircraft carrying a Pegasus II:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oLs1P.jpg&quot; alt=&quot;Stratolaunch Carrier mated to Pegasus II&quot;&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://static.businessinsider.com/image/51fc173c6bb3f7ff5c00000a/image.jpg&quot; rel=&quot;noreferrer&quot;&gt;BusinessInsider&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The carrier aircraft will also have the largest wingspan of any aircraft to date:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kH6G0.png&quot; alt=&quot;Stratolaunch Carrier Aircraft wingspan comparison&quot;&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Stratolaunch_comparison.svg#/media/File:Stratolaunch_comparison.svg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-04-24T05:27:00.490" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14348" PostTypeId="1" CreationDate="2015-04-24T10:25:15.483" Score="2" ViewCount="1213" Body="&lt;p&gt;Could you tell me who operates the hoist in the Coast Guard helicopter SAR teams?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the A&amp;amp;P technician(Flight mechanic) or the Rescue swimmer(winchman)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested to procedures from around the world, in particular inthe US, UK and Canada, but not limited to them.&lt;/p&gt;&#xA;" OwnerUserId="3317" LastEditorUserId="1467" LastEditDate="2015-04-24T10:42:58.410" LastActivityDate="2017-08-28T12:38:43.047" Title="Who operates the hoist in a Coast Guard helicopter SAR team?" Tags="&lt;search-and-rescue&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14349" PostTypeId="2" ParentId="14342" CreationDate="2015-04-24T12:45:38.563" Score="16" Body="&lt;p&gt;There are three problems with this idea:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) To make a screen strong enough to withstand the body of a 15-to-20 pound bird hitting it at 500 miles per hour, would require thick wire which would significantly block air flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Such a screen would be very liable to collect ice, so it would have to be heated to high temperature. This would be expensive and would increase the maintenance burden for the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) If part of the screen failed and broke off for any reason and went into the rotors, it would destroy the engine.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2017-10-23T14:47:05.543" LastActivityDate="2017-10-23T14:47:05.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14350" PostTypeId="2" ParentId="14342" CreationDate="2015-04-24T13:19:10.930" Score="18" Body="&lt;p&gt;Screens were actually used on the first prototypes of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot; rel=&quot;noreferrer&quot;&gt;Me-262&lt;/a&gt;, but soon abandoned when they were found to be more of a burden than a help.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look carefully at the picture of the Me-262 V3 below, you can see the spherical screens on both engine intakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eNeEI.jpg&quot; alt=&quot;Me-262 V3 on the ground  during flight preparations (1942)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, screens are used only in ground tests. See the picture below for the Rolls-Royce version:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j6gS8.jpg&quot; alt=&quot;Rolls-Royce engine test stand with bulbous intake screen&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big surface of the sphere reduces aerodynamic losses, which are small under static conditions anyway, but this contraption would obviously be totally impractical in flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-09T14:26:46.810" LastActivityDate="2015-05-09T14:26:46.810" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14351" PostTypeId="2" ParentId="14317" CreationDate="2015-04-24T13:26:55.483" Score="7" Body="&lt;p&gt;Yes - &lt;a href=&quot;http://www.eurofighter.com/news-and-events/2008/05/direct-voice-input-technology&quot; rel=&quot;nofollow&quot;&gt;Typhoon uses a &quot;Direct Voice Input&quot; (DVI)&lt;/a&gt; system. This has a limited vocabulary which allows the pilot to control non-safety critical items via voice input. The current system uses an uploaded template specific to the pilot to enable recognition. Although developments are looking at various updates including removing the dependency on pilot templates.&lt;/p&gt;&#xA;" OwnerUserId="769" LastEditorUserId="65" LastEditDate="2015-04-27T20:27:00.843" LastActivityDate="2015-04-27T20:27:00.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14352" PostTypeId="2" ParentId="14348" CreationDate="2015-04-24T15:54:59.800" Score="1" Body="&lt;p&gt;Winchmen and rescue swimmers leave the helicopter during a SAR operation, because it's their job to go down and actually rescue people. So, they can't operate the hoist. The job falls to the flight mechanic, who's the only one in the chopper who can see the rescue scene. &lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-24T15:54:59.800" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14353" PostTypeId="2" ParentId="14348" CreationDate="2015-04-24T16:14:23.973" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;who operates the hoist in the Coast Guard helicopter SAR teams?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on country and other factors, perhaps aircraft type etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the winchman descends on the end of the winch cable and does not operate the winch.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the UK, helicopter search and rescue were, until recently, mostly provided by the RAF. HM Coastguard HMCG (now part of Maritime and CoastGuard Agency - MCA)  operate SAR helicopters too and will mostly take over the SAR role.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The standard SAR crew is made up of four members: two pilots, one of whom is the aircraft captain, &lt;strong&gt;a radar operator who acts as the winch operator at the rescue scene&lt;/strong&gt; and a winchman, normally trained to paramedic standard, who will supply immediate first-aid and recovery services at the rescue site.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.raf.mod.uk/equipment/seaking.cfm&quot; rel=&quot;nofollow&quot;&gt;RAF Sea King&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Sometimes the role is taken by aircrew normally responsible for loading/unloading:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you are part of &lt;strong&gt;aircrew&lt;/strong&gt;, you would be &lt;strong&gt;responsible for loading and unloading aircraft payloads&lt;/strong&gt;, ... You would also take on extra duties according to the aircraft type and its operational role. For example, ... you might train as a &lt;strong&gt;winch operator for search-and-rescue operations&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://nationalcareersservice.direct.gov.uk/advice/planning/jobprofiles/Pages/rafnon-commissionedaircrew.aspx&quot; rel=&quot;nofollow&quot;&gt;RAF non-commissioned aircrew&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Other References&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.raf.mod.uk/rafvalley/aboutus/sartu.cfm&quot; rel=&quot;nofollow&quot;&gt;Search and Rescue Training&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.raf.mod.uk/rafsearchandrescue/rafcms/mediafiles/786C1D69_5056_A318_A8A97B2C43CB3E85.pdf&quot; rel=&quot;nofollow&quot;&gt;Working with Search and Rescue Helicopters&lt;/a&gt; &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.gov.uk/government/news/coastguard-search-and-rescue-helicopter-programme&quot; rel=&quot;nofollow&quot;&gt;Coastguard search and rescue helicopter programme&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-04-24T16:36:15.777" LastActivityDate="2015-04-24T16:36:15.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14354" PostTypeId="1" AcceptedAnswerId="14358" CreationDate="2015-04-24T16:27:36.543" Score="9" ViewCount="5759" Body="&lt;p&gt;During the mid 20th century and cold war, armies were having clear distinction between those aircraft designed as strategic bombers and those designed to be fighters for aerial combat. My understanding was that there were few exceptions to this rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the fifth generation of jet fighters include models designed normally for aerial combat but also used for strategic bombing. Old designs of strategic bombers are still being used, but it is clear that jet aircraft are being significantly improved by new developments compared to obsolete bombers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this happening? Is current warfare no longer requiring strategic bombers? Are designs of jet fighters so flexible that they can perform different missions? (usually it is the other way around, as time passes more specialization is seen).&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="1696" LastEditDate="2018-04-25T15:00:55.490" LastActivityDate="2018-04-25T19:42:06.407" Title="Are strategic bombers still useful, or are fighters taking over this role?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;bomber&gt;&lt;strategic-bomber&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14355" PostTypeId="5" CreationDate="2015-04-24T16:28:21.037" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-04-24T16:28:21.037" LastActivityDate="2015-04-24T16:28:21.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14356" PostTypeId="4" CreationDate="2015-04-24T16:28:21.037" Score="0" Body="A strategic bomber is a medium to long range heavy bomber designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2015-04-24T16:47:31.097" LastActivityDate="2015-04-24T16:47:31.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14357" PostTypeId="1" AcceptedAnswerId="14359" CreationDate="2015-04-24T16:40:19.733" Score="3" ViewCount="12754" Body="&lt;p&gt;Assume it is fully loaded (pasengers and cargo) and optimal conditions, almost no wind, etc etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long after takeoff does the plane reaches cruise speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If he goes in a straight like on the axis of the airport strip (i.e. makes no turns), how far will have it traveled when it reaches cruise speed?&lt;/p&gt;&#xA;" OwnerUserId="8257" LastEditorUserId="97" LastEditDate="2015-04-29T23:35:46.263" LastActivityDate="2015-04-29T23:35:46.263" Title="How long after takeoff for a Boeing 747-400 to reach cruise speed?" Tags="&lt;takeoff&gt;&lt;airspeed&gt;&lt;boeing-747&gt;&lt;cruise&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14358" PostTypeId="2" ParentId="14354" CreationDate="2015-04-24T17:01:23.740" Score="14" Body="&lt;p&gt;The reason that small aircraft are used in the bombing role is flexibility and cost. If you load up a B-52, it can only be in one place at one time, travel at subsonic speeds, and be expensive to operate, risking more crew and equipment. Using smaller attack jets allows reaching targets across a wider geographical area faster. And while past conflicts saw massive bombing campaigns that favored the use of large bombers, more recent conflicts have seen much less of this tactic. Smaller, more targeted strikes are more typical, where a large bomber would be overkill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at the &lt;a href=&quot;http://nation.time.com/2013/04/02/costly-flight-hours/&quot; rel=&quot;nofollow noreferrer&quot;&gt;cost per flight hour for various aircraft&lt;/a&gt;. A B-52 will cost \$70,000 per hour to operate, and a B-1B \$60,000. Compare this to an F-16C for \$23,000 or an F-15C for \$42,000. The A-10 costs \$18,000. For stealth, the costs go up to \$170,000 for a B-2 and \$70,000 for an F-22. So why send a B-52, when a few F-16's would cost the same amount? The fighters will also be able to defend themselves, and still be able to carry out a mission if an aircraft drops out. The same argument can be made for the stealthy class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/8675/1696&quot;&gt;Strategic bombers still have their uses&lt;/a&gt;, but &lt;a href=&quot;https://aviation.stackexchange.com/q/8665/1696&quot;&gt;the bomber role is much less demanding than the fighter role&lt;/a&gt;. With proper maintenance and multiple equipment upgrades, old bombers can still fly bombs to their targets just fine. Fighter jets have much more complicated requirements, such as stealth, speed, and maneuverability, where advances in technology will justify the costs of continued development of new designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are becoming more generalized because it is more efficient. In some areas such as naval aviation, this is even more critical. Why have separate planes for electronic warfare, attack, and air defense? You would be limited to a certain number of each type, with little or no cross capability. But with more generalized aircraft, you can have more aircraft with a certain capability across the fleet. If a certain capability becomes less important, you don't end up with a whole group of aircraft becoming useless. Aircraft can fulfill multiple roles in a single mission or deployment.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-04-24T17:01:23.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14359" PostTypeId="2" ParentId="14357" CreationDate="2015-04-24T17:23:24.127" Score="7" Body="&lt;p&gt;I did a search on FlightAware for 747-400 aircraft in flight, and &lt;a href=&quot;http://flightaware.com/live/aircrafttype/B744?;offset=0;sort=DESC;order=filed_ete&quot;&gt;sorted by the estimated time enroute&lt;/a&gt;. A Qantas flight &lt;a href=&quot;http://flightaware.com/live/flight/QFA18/history/20150424/0655Z/KLAX/YSSY&quot;&gt;from KLAX to YSSY&lt;/a&gt; came up. I'm assuming that for a 6500 Nm flight, at 13.5 hours, the aircraft is fairly heavy at takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight data shows a departure at 03:28:33, reaching an initial cruise level of FL300 at 03:52:59, after a continuous climb. It was at cruise speed at this point, which gives a time of &lt;strong&gt;25 minutes&lt;/strong&gt; after takeoff. Comparing the coordinates of these two reporting points gives a distance of about &lt;strong&gt;180 Nm&lt;/strong&gt;, which from the track is pretty straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you just want to know when it reached a speed around that of cruise, this was about &lt;strong&gt;10 minutes and 80 Nm earlier&lt;/strong&gt; in the climb, when it reached a ground speed of about 480 knots.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-04-24T17:23:24.127" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14360" PostTypeId="1" AcceptedAnswerId="14366" CreationDate="2015-04-24T18:06:45.040" Score="17" ViewCount="5929" Body="&lt;p&gt;I fly in/out of a small international airport occasionally, the runways are quite long. It is not unusual to land half-way or even three-quarters down the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When doing this, pilots request long landings from ATC. I once did not request a long landing and did anyway and got chewed out a bit from ATC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it mandatory to request a long landing or is it more of a courtesy? Where is this information documentated? &lt;/p&gt;&#xA;" OwnerUserId="553" LastActivityDate="2018-06-29T18:47:25.853" Title="Why should I request a long landing?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14361" PostTypeId="2" ParentId="14360" CreationDate="2015-04-24T18:20:12.607" Score="6" Body="&lt;p&gt;Long landings are requested mostly by GA pilots (although airlines can do it too) on longer runways. ATC is informed about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is parked near the end of the runway, or needs to get there, long landing is used as it is faster to fly at 80 knots than to taxi at a much lower speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure why ATC didn't like it in your particular situation. It could be that they were expecting you to get off the runway sooner, which you didn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nlr-atsi.nl/downloads/landing-long-why-does-it-happen.pdf&quot;&gt;This PDF&lt;/a&gt; explains this. I couldn't find any regulations related to it.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-04-24T18:20:12.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14362" PostTypeId="2" ParentId="14354" CreationDate="2015-04-24T19:23:50.953" Score="9" Body="&lt;p&gt;Fighter aircraft have steadily grown in size and mass over the last century, as performance requirements and their armament load spiraled upwards. This has reached a point where a single seater today will carry more ordnance and fly farther than a strategic bomber from 70 years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With their size and performance, the price of a single aircraft went through the roof, such that now one single aircraft design must fulfill many roles where 70 years ago several companies could offer competing designs for specialized roles. The development of strategic bombers has effectively stopped several decades ago with the &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;nofollow noreferrer&quot;&gt;XB-70&lt;/a&gt;, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-1&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Tupolev_Tu-160&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-160&lt;/a&gt; because it became unaffordable. Note that I did not mention the B-2: It must be judged an economic failure, being so expensive that it rarely is used in earnest for fear of losing just a single plane. Instead, bombing missions today are performed by the smallest and lightest front line fighters, because here single-digit losses can still be tolerated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even attempts to break this spiral (the &lt;a href=&quot;http://en.wikipedia.org/wiki/Folland_Gnat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Folland Gnat&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_F-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop F-5&lt;/a&gt; come to mind) went nowhere. Note that both types were not accepted in their intended role by their respective nations, but could only serve in their training variants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today we keep old designs up to date by updating systems, but in many cases the airframe flew first before today's pilots were born. Engineers will rarely work on more than one new frontline combat aircraft design in their whole lifetime because development cycles now stretch over three decades. Compare that to the situation in WWI, when aircraft designs normally became obsolete within one year of their introduction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strategic bombing is also no longer part of military doctrine. Instead, the goal is to limit escalation and use highly precise strikes against selected targets. Compare that with the situation in WWII, when the declared goal of bombing was to wear enemy morale down and kill as many people as possible. Back then, collateral damage was a desired side effect, whereas it has become indefensible today. Let's not forget that one of the first (relatively) long-range bombing missions in history targeted a matinée circus performance in Karlsruhe, when heroic French pilots managed to take 120 lives, mostly children and their nannies, on an afternoon raid in June 1916.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be blunt, classical strategic bombing is as dead as the parrot in that &lt;a href=&quot;https://www.youtube.com/watch?v=4vuW6tQ0218&quot; rel=&quot;nofollow noreferrer&quot;&gt;Monty Python sketch&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-04-25T19:42:06.407" LastActivityDate="2018-04-25T19:42:06.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14363" PostTypeId="2" ParentId="14360" CreationDate="2015-04-24T19:31:25.890" Score="5" Body="&lt;p&gt;ATC doesn't like unannounced long landings because unless they are informed of what you're doing, they will be concerned that you're just too fast or too high and might run off the end of the runway.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-04-24T19:31:25.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14364" PostTypeId="2" ParentId="8884" CreationDate="2015-04-24T19:39:39.417" Score="2" Body="&lt;p&gt;For large solar aircraft, it is advantageous to be flying above the clouds, for predictable and uninterrupted solar performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are flight test areas (airfields with a large-enough flight range) where meteorological conditions and test availability allows companies to fly several sorties and calibrate their flight-performance parameters. &lt;a href=&quot;http://atlascenter.aero/en/atlas_aa23.html&quot; rel=&quot;nofollow&quot;&gt;Spain&lt;/a&gt;, &lt;a href=&quot;http://www.vidseltestrange.com/&quot; rel=&quot;nofollow&quot;&gt;Sweden&lt;/a&gt;, &lt;a href=&quot;http://www.ccuvs.com/foremost-centre/&quot; rel=&quot;nofollow&quot;&gt;Canada&lt;/a&gt; and USA has these sites. The FAA has a list of &lt;a href=&quot;https://www.faa.gov/uas/legislative_programs/test_sites/&quot; rel=&quot;nofollow&quot;&gt;US test sites on the web&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Solar-powered aircraft have constant weight and CG which makes the tests much simpler than other fuel-powered aircaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For personal flight tests, flying a circular or figure-8 pattern at a constant altitude, with as little turbulence as possible, for a full charge, would reveal the necessary information for flight times. But if the flight takes longer than half an hour, it would be best to have the autopilot fly. So that you could get the piloting efforts (and errors) out of the equation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, time of the day and day of the year are important parameters but you can calculate their effects on your solar panels by hand.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastEditorUserId="8079" LastEditDate="2015-04-25T03:57:21.480" LastActivityDate="2015-04-25T03:57:21.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14365" PostTypeId="2" ParentId="14360" CreationDate="2015-04-24T19:52:55.000" Score="11" Body="&lt;p&gt;When you are cleared to land, you own the entire runway until you exit.  Use it all if you must.  (One exception to this is at Oshkosh, during the annual AirVenture when as many as three airplanes are cleared to land on the same runway at the same time: one short, one medium, and one long as demarcated by colored dots.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, at a busy airport you are expected to land reasonably close to the arrival end, and to exit the runway promptly.  This is an important component of keeping traffic moving smoothly at a busy airport, so if you want to land long you should inform the tower of your request.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good reason to land long:  If the controller has positioned you too close behind a large airliner so that wake turbulence is an issue, tell the controller that you want to land long.  Wingtip vortices stop as soon as the aircraft lands, and you want your touchdown point beyond the large airliner's touchdown point.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-04-27T15:25:58.227" LastActivityDate="2015-04-27T15:25:58.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14366" PostTypeId="2" ParentId="14360" CreationDate="2015-04-24T19:58:26.487" Score="18" Body="&lt;p&gt;There's no mention that I can find of &quot;landing long&quot; (&quot;landing deep&quot; is sometimes used outside the US) in the FAA's &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/PCG_4-03-14.pdf&quot;&gt;P/CG&lt;/a&gt;, &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/AIM_Basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; or &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC procedures&lt;/a&gt;. So it's fairly safe to say that it's an unofficial instruction (assuming I didn't miss it somewhere).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason for doing it is to avoid a long taxi after landing, but I suppose there could be other reasons too, like coming in too high on a long runway or avoiding wake turbulence. The point of requesting it - and not just doing it - is that it may mess up sequencing at a busy airport because you take more time to clear the runway, with the result that the tower has to instruct the aircraft following you to go around. As my first instructor said, &quot;once you're cleared to land it's your runway&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never been asked by ATC to do it but I have been asked by the tower to &quot;land short&quot;, to minimize my time on the runway and let an airline flight take off ASAP. However, it was clearly phrased as an informal request, not an instruction; something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N12345 Clear to land 36L, appreciate a short landing if you can manage it&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I think the conclusion is that landing &quot;short&quot; or &quot;long&quot; is simply an informal way for pilots and ATC to make things work a bit more smoothly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-04-24T19:58:26.487" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14367" PostTypeId="1" CreationDate="2015-04-24T21:31:10.043" Score="1" ViewCount="73" Body="&lt;p&gt;I assume that the fuselage and tail fin can generate lift when flying sideways with a constant heading and a little pitch up (er, yaw right assuming left wing down) will introduce a vertical component to the thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is that all there is?  What else might be going on?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-04-24T21:36:28.920" LastActivityDate="2015-04-24T21:36:28.920" Title="Flying sideways, how is it done?" Tags="&lt;aerodynamics&gt;&lt;aerobatics&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2015-04-24T21:50:18.580" ContentLicense="CC BY-SA 3.0" />
  <row Id="14370" PostTypeId="2" ParentId="9144" CreationDate="2015-04-25T04:37:51.647" Score="2" Body="&lt;p&gt;For simple platforms, &lt;a href=&quot;http://en.wikipedia.org/wiki/Load_cell&quot; rel=&quot;nofollow&quot;&gt;load-cells&lt;/a&gt; can be attached in between the propulsion system and the airframe. This allows the propulsion force to be measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This force data excludes aerodynamic integration effects, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;propeller stream effects for nose-propped aircraft, and fuselage blockage for rear-propped aircraft&lt;/li&gt;&#xA;&lt;li&gt;engine cooling drag (which is an aerodynamic property of the particular engine/propulsion integration)&lt;/li&gt;&#xA;&lt;li&gt;accelerated air over the airframe (in-body jet engines, or propeller aircraft)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is not an absolute requirement to assess the performance of an engine. Especially, if the aircraft can fly with another engine or if the drag characteristics of the aircraft is known by some valid method, instead of a direct measurement, indirect calculations can be done. For example, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;for constant speed and level flight, thrust = drag&lt;/li&gt;&#xA;&lt;li&gt;for accelerated level flight F_net=Mass * acceleration, etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-04-25T04:37:51.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14371" PostTypeId="2" ParentId="14360" CreationDate="2015-04-25T07:24:50.557" Score="5" Body="&lt;p&gt;In EASA land, you can also be asked to make a long landing because the controller will want to clear another aircraft to land behind you, although you are still occupying the runway. This tool is called &lt;strong&gt;Reduced Runway Separation&lt;/strong&gt; and requires the preceding aircraft to be beyond a certain distance measured from the runway threshold, before the subsequent approaching aircraft can be cleared to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related question:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/7661/572&quot;&gt;When is an aircraft cleared to land?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-25T07:24:50.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14373" PostTypeId="1" AcceptedAnswerId="14376" CreationDate="2015-04-25T09:21:26.223" Score="59" ViewCount="7794" Body="&lt;p&gt;Stealth planes can't be seen (very well) on radar. So one stealth plane should be unable to locate another stealth plane on its radar and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how would one stealth plane locate another, friendly, stealth plane?&lt;/p&gt;&#xA;" OwnerUserId="1395" LastEditorUserId="4474" LastEditDate="2015-04-25T18:49:32.300" LastActivityDate="2018-01-19T18:54:52.767" Title="How do friendly stealth planes locate each other?" Tags="&lt;military&gt;&lt;stealth&gt;&lt;flying-in-formation&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14374" PostTypeId="2" ParentId="14360" CreationDate="2015-04-25T10:20:12.980" Score="7" Body="&lt;p&gt;I don't think it is documented anywhere that you must inform the controller if you want to land long. But you should state your intentions clearly as a courtesy to the controller and by effect other aircraft that you share the airport with. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller will expect a small aircraft to take the first runway exit. They plan the arrival stream accordingly. From experience they know it will take a Cessna 150, for example, 40 seconds between overflying the threshold and vacating at the first exit. Thus they can space the next aircraft appropriately so that they can give a landing clearance in time after you vacate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you unexpectedly fly all the way to the second half of the runway before landing it will take much longer between overflying the threshold and vacating the runway. This will make the margins for giving the landing clearance to the aircraft behind you much smaller and may even force the controller to order the big jet on your tail to go around. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For screwing up somebody else's plan and causing others to go-around you get shouted at sometimes.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2015-04-26T15:09:47.813" LastActivityDate="2015-04-26T15:09:47.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14376" PostTypeId="2" ParentId="14373" CreationDate="2015-04-25T12:12:49.717" Score="62" Body="&lt;p&gt;The accounts that have been published of F-117 missions indicate that they generally flew single-ship, rather than formation missions, and it seems probable that B-2 aircraft do likewise.  So in a sense, the important question for those aircraft isn't &quot;how do I know where (another stealth aircraft operating nearby) IS,&quot; but &quot;how do I ensure that we don't collide with each other,&quot; and that's a much easier question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several ways to &quot;deconflict&quot; multiple aircraft operating in relatively close proximity that don't involve seeing or painting each other on radar.  One aircraft operates at one altitude, another operates at a different altitude is one method, while timing over a point (you get to waypoint ABC no later than 19:00:00, and I'll be there no sooner than 19:00:30) is another, and physical separation (you stay west of this longitude line, I stay east) is another.  In practice, all of these can be combined to ensure that &quot;your&quot; mission is deconflicted from &quot;my&quot; mission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of note, it isn't only stealth aircraft that will use tactics like this.  Helicopters operating blacked out at night don't have air-to-air radar, and even with NVG's, the ability to see each other isn't reliable enough to plan on &quot;see and avoid&quot; and the &quot;big sky theory&quot; to preclude a mid-air, so they'll use some fairly detailed deconfliction plans incorporating separation in space and time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More recent stealth aircraft such as the F-22 and F-35 are &lt;a href=&quot;http://www.f22fighter.com/avionics.htm#2.4%20Inter%20/%20Intra-Flight%20Data%20Link%20(IFDL)&quot;&gt;reported&lt;/a&gt; to have &lt;a href=&quot;http://en.wikipedia.org/wiki/Multifunction_Advanced_Data_Link&quot;&gt;datalink&lt;/a&gt; capabilities so that they can &quot;see&quot; each other without radar, by means of an encrypted, stealthy broadcast of each aircraft's position and track.  This would allow multiple aircraft to fly in formation (not close formation, but perhaps 1000' or more apart), and to work with other aircraft equipped with the same datalink, so even though the bad guys would only be able to see the non-stealth aircraft on radar, the friendlies could all see each other.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-04-25T12:20:17.777" LastActivityDate="2015-04-25T12:20:17.777" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14379" PostTypeId="1" AcceptedAnswerId="14388" CreationDate="2015-04-25T12:25:51.047" Score="8" ViewCount="9334" Body="&lt;p&gt;Sometimes I like to fly a bit in flight simulator in &lt;a href=&quot;https://www.google.com/earth/&quot;&gt;Google Earth&lt;/a&gt; (not the Pro version), and I was wondering how realistic it is. There are two planes you can fly. I included some stuff I personally tried.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;F-16&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max altitude (starting from ground): 46200 ft (14081.8 m)&lt;/li&gt;&#xA;&lt;li&gt;Max altitude (starting from the highest google earth let me start): 80000 ft (24384 m)&lt;/li&gt;&#xA;&lt;li&gt;Max speed while falling down: 1450 knots (2685.4 km/h)&lt;/li&gt;&#xA;&lt;li&gt;Max vertical speed: 980 knots (1814.96 km/h)&lt;/li&gt;&#xA;&lt;li&gt;Flies rather stable, I can do some aggressive maneuvers without any problems. Difficult to land. When I'm very high, it's difficult to get control of the aileron.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;SR22&lt;/strong&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max altitude (from ground): 19800 ft (6035.04 m)&lt;/li&gt;&#xA;&lt;li&gt;Max altitude (from highset starting point): 60000+ ft (18288+ m)&lt;/li&gt;&#xA;&lt;li&gt;Max speed while falling down: 550 knots (1018.6 km/h)&lt;/li&gt;&#xA;&lt;li&gt;Max vertical speed: 155 knots (287.06 km/h)&lt;/li&gt;&#xA;&lt;li&gt;Not very powerful. Quite unstable (aileron always moves by itself). Easy to land.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Interestingly, Google Earth allows you to fly beneath the surface of oceans, and it flies exactly the same as in the air. The support for taking off from a real airport is rather limited, but it's there. It supports a full ROM afaik.&lt;/p&gt;&#xA;" OwnerUserId="8262" LastActivityDate="2019-03-03T03:27:21.803" Title="How realistic is Google Earth Flight Simulator?" Tags="&lt;flight-simulator&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14380" PostTypeId="2" ParentId="14373" CreationDate="2015-04-25T13:31:37.640" Score="30" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=ifmRgQX82O4&quot; rel=&quot;noreferrer&quot;&gt;To not be detected&lt;/a&gt;, it is essential to suppress any radiation coming from the stealth airplane. Therefore, radar is not an option and only passive sensing is possible. When stealth aircraft fly in formation, they keep visual contact and avoid &lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_meteorological_conditions&quot; rel=&quot;noreferrer&quot;&gt;IMC&lt;/a&gt; flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To enable ship-to-ship communication, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_F-117_Nighthawk&quot; rel=&quot;noreferrer&quot;&gt;F-117&lt;/a&gt; has an optical datalink which uses red laser light to transmit the pilot's voice to another F-117 flying nearby.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-10-08T09:33:56.360" LastActivityDate="2016-10-08T09:33:56.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14381" PostTypeId="1" CreationDate="2015-04-25T17:52:38.137" Score="3" ViewCount="1368" Body="&lt;p&gt;Technically what differences are there between a take off and a stall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I understand, when &lt;strong&gt;stalling&lt;/strong&gt; the aircraft will lose lift when a certain angle is met. On a &lt;strong&gt;takeoff&lt;/strong&gt; the aircraft will pitch the nose up but the effects are different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What affects this? Is it the effect of the relative airflow or something else?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="65" LastEditDate="2015-04-27T13:28:15.757" LastActivityDate="2015-05-04T23:44:04.437" Title="How are takeoff and stall different from each other?" Tags="&lt;takeoff&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14382" PostTypeId="1" AcceptedAnswerId="14383" CreationDate="2015-04-25T20:08:23.823" Score="36" ViewCount="3617" Body="&lt;p&gt;Many airlines (at least here in the U.S.) have flight numbers that use different aircraft for different legs of the flight. For example, Delta 158 uses a 747-400 from Incheon International in Seoul to Detroit, then an A320 from Detroit to Boston a couple of hours later. This got me to wondering what happens if an earlier leg is delayed such that it's arriving around the time that the next leg is departing the same airport? In particular:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will both flights use the same radio call sign? That is, will they both be &quot;Delta 158&quot; (ignoring the &quot;Heavy&quot; difference in this particular case?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they do use the same call sign, how do controllers know which one is talking, especially if they end up on the same frequency at some point?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like this sort of situation would happen somewhat frequently, at least here in the U.S. where it's common for a given flight number to include multiple legs and for those legs to operate on different aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is related, but doesn't actually address this particular question: &lt;a href=&quot;https://aviation.stackexchange.com/q/6280/755&quot;&gt;Why are some ATC call signs different than the flight number?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2017-12-13T03:16:09.960" Title="How are duplicate call signs dealt with?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;radio-communications&gt;&lt;call-sign&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14383" PostTypeId="2" ParentId="14382" CreationDate="2015-04-25T20:24:07.827" Score="52" Body="&lt;p&gt;The scenario you're asking about is common.  Let's say that your Delta 158 from South Korea to Detroit is running several hours late, and the decision is made to operate the A320 DTW-BOS on time.  ATC &lt;strong&gt;doesn't&lt;/strong&gt; accept having two aircraft flying with the same callsign at once due to exactly the sort of confusion you suggest, so something has to change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What will happen is that the second flight -- i.e. the one that isn't already airborne, will get a new ATC callsign.  Sometimes you'll hear something like &quot;Delta 158&lt;strong&gt;A&lt;/strong&gt;&quot; as the callsign of the flight, or they may use something entirely different like &quot;Delta &lt;strong&gt;9&lt;/strong&gt;158&quot; as the ATC callsign for that flight.  Each company will have their own method of resolving the conflict; some use letters, others don't.  Some can go to &quot;9000 + original flight number,&quot; and others will simply use something like 9001 for the first &quot;stubbed out&quot; flight that day, 9002 for the next, and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, the basic answer is that the ATC callsign of the flight changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which does NOT mean, incidentally, that the flight number as far as the passengers are concerned has changed.  It's possible to be &quot;Delta 9158&quot; or &quot;Delta 9001&quot; or &quot;Delta 158A&quot; or whatever for ATC and still be &quot;Flight 158&quot; when talking on the PA to the passengers.  The fact that the ATC callsign changed is transparent to the rest of the operation, since reservations, ticket counter, baggage handling, and so forth isn't upset when 158 ICN-DTW happens to overlap (in time) 158 DTW-BOS.  Only ATC worries about that, so the fix is only visible to them (and the pilots &amp;amp; dispatchers).&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2017-12-13T03:16:09.960" LastActivityDate="2017-12-13T03:16:09.960" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="14386" PostTypeId="2" ParentId="14381" CreationDate="2015-04-26T04:19:03.383" Score="5" Body="&lt;p&gt;On take-off the pitch is increased to increase lift, but only to a point well before stall occurs. An aircraft's minimum speed is defined by the maximum lift it can create before the flow over the wings stalls, and the high-pitch attitude is only attained when the aircraft flies faster than that. As soon as lift is sufficient for lift-off, further pitch increases are increasing the flight path angle. If the aircraft keeps accelerating during the initial climb, stalling is impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically, both are very different. Their only commonality is that they involve high angles of attack.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-04-26T04:19:03.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14387" PostTypeId="2" ParentId="12671" CreationDate="2015-04-26T08:33:45.607" Score="0" Body="&lt;p&gt;A very common practice in the military is to take off with almost zero fuel and to refuel right after the initial climb to altitude, when operating fast movers from forward operating bases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The practice occurs for fighter jets because their wings are designed for high speed, thus would require a very long runway to be able to carry their full weapons compliment into the air with their fuel. By sending up the fuel on cargo style planes, they can overall reduce the runway length required to fly fighters with a full combat load out (as the cargo planes are designed to lift things).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once in the air the fighters are moving much faster, so they can carry the extra weight easily. The extra weight in the combat load out was decided to be fuel simply because it is easier to refuel in mid air than it is to rearm in midair (missiles cannot be easily piped).&lt;/p&gt;&#xA;" OwnerUserId="600" LastActivityDate="2015-04-26T08:33:45.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14388" PostTypeId="2" ParentId="14379" CreationDate="2015-04-26T09:10:11.250" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How realistic is Google Earth Flight Simulator?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is very &lt;strong&gt;unrealistic&lt;/strong&gt; in most respects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe there are a number of important ways you can measure realism from a pilot's perspective:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;view out the windows&lt;/li&gt;&#xA;&lt;li&gt;appearance of instrument panel&lt;/li&gt;&#xA;&lt;li&gt;mode of operation of pilot aids like autopilot, autothrottle&lt;/li&gt;&#xA;&lt;li&gt;flying controls&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;physical character&lt;/li&gt;&#xA;&lt;li&gt;responsiveness&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;interaction with ATC &lt;/li&gt;&#xA;&lt;li&gt;effects of wind, weather, turbulence, rain, ice&lt;/li&gt;&#xA;&lt;li&gt;aeronautical characteristics of aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It would be easy to focus solely on the last of these, but from my perspective this is not really the most important. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a few dissimilarities that occur to me.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;View&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The SR22 doesn't have a HUD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm pretty sure the SR22 cockpit windows would take up a much greater area of my vision than my computer screen does. Especially peripheral vision. Also in a real SR22, there is important stuff to look at below the windows.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Instruments&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Do these look alike?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6XEup.png&quot; alt=&quot;Actual SR22 cockpit&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/EBk4r.png&quot; alt=&quot;SR22 PFD&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/QuCC3.jpg&quot; alt=&quot;Google Earth SR22&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Controls&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In Google Earth you don't have anything like the range of controls that have to be used, where are all the switches, knobs and other dohickeys you find in the real SR22?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Waving a mouse around is &lt;strong&gt;nothing like&lt;/strong&gt; moving a control column around. With a control column you have a much different sense of the position of the controls. Moving a mouse involves completely different muscles and different motions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving a throttle lever is completely different to pressing PgUp and PgDn buttons to move a throttle position in increments&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Feel&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In Google Earth you don't hear any engine, you dont feel any vibration, you don't feel any turbulence, you don't feel anything in an uncoordinated turn or when pulling out of a dive, you don't feel the unevenness of a runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to really feel oriented in a simulator when your sense of balance and peripheral vision tell you you are sitting upright at your desk, not inverted and spinning towards the ground.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Disclaimer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I'm not a pilot, I have sat in the pilot's seat of a small Cessna and manipulated the control-column and rudder to make a few turns and attempt to maintain speed and altitude under the direction of a pilot. I've done the same in a glider, and I have done some take-offs and landings in a fairly amazing full (though static) commercial 737 simulator with full cockpit reproduction (all seats, panels, motorised levers, switches etc that you'd find in a real 737 cockpit, wired to a large rack of computers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fSdrV.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;sup&gt;&lt;em&gt;A more realistic simulator&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Google Earth is nothing like any of them in almost any respect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a fun game though.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-04-26T10:12:13.183" LastActivityDate="2015-04-26T10:12:13.183" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="14389" PostTypeId="1" CreationDate="2015-04-26T14:56:35.997" Score="9" ViewCount="936" Body="&lt;p&gt;According to &lt;a href=&quot;http://av8.home.comcast.net/~av8/onlinestorage/fltplanchange.pdf&quot;&gt;someone on the internet&lt;/a&gt;, the FAA intends to discontinue accepting domestic flight plans and switch to ICAO-only in October.  I've also heard this around the airport, but been unable to verify it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The provided link says that the FAA is &lt;em&gt;proposing&lt;/em&gt; to phase out domestic plans, but doesn't say that they've committed to it, nor does it give a date.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA is also &lt;strong&gt;proposing&lt;/strong&gt; to implement flight plan filing for civil&#xA;  aircraft exclusively under the format used by the International Civil&#xA;  Aviation Organization (ICAO).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there an official FAA publication that verifies the FAA's intent to stop accepting domestic flight plans on October 1, 2015?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2016-01-28T17:44:27.320" Title="Does the FAA intend to discontinue domestic flight plans and switch to ICAO-only on October 1, 2015?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14391" PostTypeId="1" AcceptedAnswerId="14393" CreationDate="2015-04-26T16:05:20.910" Score="21" ViewCount="10567" Body="&lt;p&gt;The EASA regulations give the following requirement for number of emergency exits:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6V8JZ.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If then the Airbus A320 is certified to carry 180 passengers, it seems to me that it falls just outside the minimum bracket of 2x Type I exits and 2x Type III exits and it should then have a pair of additional Type III exits to be able to accommodate 180 passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, various sources give the emergency exits as &lt;a href=&quot;http://aviation-safety.net/airlinesafety/exits/exit.php?type=022-0&quot; rel=&quot;noreferrer&quot;&gt;(link)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Dc1N.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This configuration, in my opinion only allows 179 passengers, not 180.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some clause I am missing? &lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="97" LastEditDate="2015-04-26T20:17:45.737" LastActivityDate="2015-04-27T05:15:05.317" Title="Why is the Airbus A320 permitted to carry 180 passengers, instead of the maximum 179 allowed?" Tags="&lt;aircraft-design&gt;&lt;emergency&gt;&lt;easa-regulations&gt;&lt;airbus-a320&gt;&lt;cabin-design&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14393" PostTypeId="2" ParentId="14391" CreationDate="2015-04-26T16:33:51.027" Score="35" Body="&lt;p&gt;See Page 9 of &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/Explanatory_Note_TCDS_EASA%20A%20064_Airbus_A318_A319_A320_A321_Iss_07_20150%20%20%20%20%283%29.pdf&quot;&gt;TCDS A.064 ANNEX - Airbus A318, A319, A320, A321 - Special Conditions&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TCDS A.064 ANNEX - Airbus A318, A319, A320, A321 - Special Conditions  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;EQUIVALENT SAFETY FINDING         E-2107: Passenger Extension to 180&#xA;APPLICABILITY:                    A320&#xA;REQUIREMENTS:                     JAR 25.807&#xA;ADVISORY MATERIAL:                N/A&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;  &#xA;  &lt;p&gt;Statement of Issue:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An application was made on September 30, 1992 to JAA for certification of maximum number of passengers of 180.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Paragraph 25.807(c)(1) of JAR specifies for passenger seating configuration, the number and&#xA;  types of Emergency Exits for each side of the fuselage.&#xA;  The maximum seating capacity allowable under JAR 25.807(c)(1) for A320 exit configuration is&#xA;  179 (2 Type I and 2 Type III).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, the exits size for front and rear doors on the A320 is such (32x73 inches) that they&#xA;  are oversized Type I and therefore can be considered as a non standard exit arrangement.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The same exit size is being used on a derivative of the A320, for which Latin Square Tests&#xA;  have been conducted in order to establish an appropriate rating for that kind of exits. These&#xA;  tests have shown that, when associated with the performance of the slide installed at these&#xA;  exits, a rating of 55 passengers is appropriate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It should also be noted that the full scale emergency evacuation demonstration of the A320&#xA;  with 179 passengers has demonstrated compliance with JAR 25.803(c) with sufficient margin&#xA;  to justify 180 passengers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Under those conditions, a maximum capacity of 180 passengers is requested for the A320.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;JAA Conclusion:&#xA;  Based upon the demonstrated higher rating for the floor level exits and the adequate margins&#xA;  for 179 passengers shown in the 90 seconds demonstration, and used as a basis to show&#xA;  compliance to JAR 25.803(c), the JAA accept 180 passengers as the maximum capacity for the&#xA;  A320 on the basis of an Equivalent Safety Finding.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-04-26T16:33:51.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14394" PostTypeId="2" ParentId="14391" CreationDate="2015-04-26T16:37:03.280" Score="4" Body="&lt;p&gt;The table you posted is no more valid as per &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/agency-measures-docs-certification-specifications-CS-25-00-CS-25-Amdt-12-Change-Information.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CS-25 Amendment 12 (PDF)&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Now each Type I allows for 45 passengers and each Type III allows for 35.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Type and  number  required.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;The maximum number of passenger seats&#xA;permitted depends on the type and number of exits installed on each&#xA;side of the fuselage. Except as further restricted in sub&#xA;paragraphs(g)(1) through (g)(9) of this paragraph, the maximum number&#xA;of passenger seats permitted for each exit of a specific type&#xA;installed on each side of the fuselage is as follows:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;pre&gt;&lt;code&gt;TypeA  110&#xA;TypeB   75 &#xA;TypeC   55 &#xA;TypeI   45 &#xA;TypeII  40 &#xA;TypeIII 35 &#xA;TypeIV   9&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;p&gt;The subparagraphs that apply to the A320:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(6) For a passenger seating configuration of more than 110 seats, the&#xA;emergency exits on each side of the fuselage must include at least two&#xA;Type I or larger exits.&lt;/p&gt;&#xA;&lt;p&gt;(7) The combined maximum number of passenger&#xA;seats permitted for all Type III exits is 70, and the combined maximum&#xA;number of passenger seats permitted for two TypeIII exits on each side&#xA;of the fuselage that are separated by fewer than three passenger seat&#xA;rows is 65.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-27T05:15:05.317" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14395" PostTypeId="2" ParentId="14389" CreationDate="2015-04-26T18:29:53.593" Score="8" Body="&lt;p&gt;The link from your question paraphrases and links to &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/changes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;“Flight Service Program Changes,”&lt;/a&gt; of which the April 13, 2015 7:49:56 AM EDT revision is reproduced below with &lt;strong&gt;added emphasis in boldface.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h1&gt;Flight Service Program Changes&lt;/h1&gt;&#xA;  &#xA;  &lt;p&gt;Recognizing a shift in users’ preferences for automated services, the&#xA;  FAA is changing its Flight Service operation to make it more efficient&#xA;  and reduce costs. The agency will continue to maintain the highest&#xA;  level of safety.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The changes come as general aviation pilots are transitioning from&#xA;  traditional Flight Service assistance to more automated and web-based&#xA;  tools to obtain services. Through the use of updated technology Flight&#xA;  Service is taking the opportunity to eliminate redundancies and&#xA;  underutilized services.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“None of these changes will affect core flight service safety&#xA;  functions such as search and rescue, emergency services, Notice to&#xA;  Airmen (NOTAM) entry and dissemination, and pilot weather reports,”&#xA;  said Steven Villanueva, Deputy Director Flight Service, in the ATO's&#xA;  System Operations Service Unit. “We are phasing in the changes to ease&#xA;  the transition for users,” he added.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;On October 1, 2015, the FAA will consolidate Flight Watch services&#xA;  into routine flight services inflight frequencies to eliminate&#xA;  unnecessary duplication of service and provide greater convenience for&#xA;  pilots. These services provide inflight weather information to pilots.&#xA;  After that date, these services will be available on the same&#xA;  frequencies that pilots use to open and close flight plans and to&#xA;  receive updates on NOTAMs or Temporary Flight Restrictions (TFRs).&#xA;  Dedicated Flight Watch frequencies will be decommissioned.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The FAA is proposing to phase out legacy Remote Airport Advisory&#xA;  Service. Seven of the airports do not meet the Agency's criteria for&#xA;  receiving advisory service. Flight Service is collaborating with our&#xA;  user groups on possible impacts and will be posting the proposed&#xA;  change in the Federal Register for public comment.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;The FAA is also proposing to implement flight plan filing for civil&#xA;  aircraft exclusively under the format used by the International Civil&#xA;  Aviation Organization (ICAO).&lt;/strong&gt; Flight plans contain specific&#xA;  information relating to the proposed flight of an aircraft and&#xA;  controllers use them to provide air traffic services. Today pilots&#xA;  file flight plans in the U.S. under either the domestic or ICAO&#xA;  format. The use of one format will simplify the process and align U.S.&#xA;  flight plans within ICAO standards.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;General aviation pilots increasingly have turned to automation in&#xA;  recent years to file flight plans and receive pre-flight briefings.&#xA;  New technology such as ADS-B is providing more inflight options to&#xA;  pilots. Flight Service will incorporate the industry's newest&#xA;  technologies and reduce or eliminate other functions to create&#xA;  efficiencies and value. The changes to Flight Watch and RAA are the&#xA;  first in what is anticipated to be a series of right-sizing&#xA;  initiatives surrounding flight services provided to pilots.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/res_links/flight_service_feedback/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Send your comments, questions, and suggestions&lt;/a&gt; to us and share your&#xA;  thoughts and ideas.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/faq/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Service National Airspace Initiative (FSNI) Frequently Asked&#xA;  Questions (FAQ)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The linked &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/faq/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAQ&lt;/a&gt; list contains a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/faq/#longterm&quot; rel=&quot;nofollow noreferrer&quot;&gt;question similar to yours&lt;/a&gt;, quoted below including the boldface from the original. Note the first sub-bullet under Flight Plan Filing that states the intent but does not provide a specific date.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h3&gt;What changes will be made in the Long Term?&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;Long term changes are being worked with stakeholders. Increased usage&#xA;  of technology and automation and less reliance on human delivered&#xA;  services will be considered. These changes include:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Emergency Frequencies&lt;/strong&gt; — Pilots, when in distress and using an emergency frequency (121.5MHz), will be responded to by an Air Traffic&#xA;  Control (ATC) specialist with surveillance capability, improving the&#xA;  timeliness of emergency handling.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Flight Plan Filing&lt;/strong&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Increased automation that will provide a pilot numerous alternatives for flight plan filing, modification, activation and closure&lt;/li&gt;&#xA;  &lt;li&gt;Transition to exclusive International Civil Aviation Organization (ICAO) format for civil aircraft&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Search And Rescue (SAR)&lt;/strong&gt; — Increase automation to include Automated Activation and Closure of flight plans&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Relaying Instrument Flight Rules (IFR) Clearances&lt;/strong&gt; — Flight Service is working with Air Traffic Control (ATC) to develop alternative solutions to enable pilots to talk directly to an air traffic control facility when requesting an IFR clearance.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also the related Aviation.SE question &lt;a href=&quot;https://aviation.stackexchange.com/q/12912/2143&quot;&gt;Will the frequency 122.000 MHz no longer be used for Flight Watch after October 1st 2015?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-04-26T18:29:53.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14396" PostTypeId="1" AcceptedAnswerId="14397" CreationDate="2015-04-26T20:19:22.527" Score="24" ViewCount="11280" Body="&lt;p&gt;Currently the German Luftwaffe has &lt;a href=&quot;https://en.wikipedia.org/wiki/Panavia_Tornado#German_Air_Force_.28Luftwaffe.29&quot;&gt;Panavia Tornados&lt;/a&gt; to deliver American nuclear bombs &lt;a href=&quot;https://en.wikipedia.org/wiki/Nuclear_sharing&quot;&gt;in case of war&lt;/a&gt;. The bombers are getting older and are currently modernized. The German Luftwaffe also has &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot;&gt;Eurofighter Typhoons&lt;/a&gt; which are said to not be able to deliver nuclear weapons. &lt;em&gt;Why is that so?&lt;/em&gt; (Same goes for the F-35 and the F-22)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AFAIK all that's needed for an aircraft to deliver nuclear bombs is&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The ability to actually carry the bombs, which probably conform to some standard &quot;form factor&quot;.&lt;/li&gt;&#xA;&lt;li&gt;Some special electronics for arming the bombs, which must be installed into the bomber - this probably also follows some standards.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Is that all? I seem to remember some special aerobatic maneuver the aircraft should be able to perform to allow the survival of the crew. Does that exist and is it a problem for modern fighter/bomber aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1360" LastEditorUserId="1696" LastEditDate="2015-04-26T21:24:57.710" LastActivityDate="2017-01-08T22:13:43.640" Title="What makes a bomber able to deliver nuclear bombs?" Tags="&lt;aircraft-design&gt;&lt;bomber&gt;&lt;ordnance&gt;" AnswerCount="6" CommentCount="13" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14397" PostTypeId="2" ParentId="14396" CreationDate="2015-04-26T22:21:09.250" Score="20" Body="&lt;p&gt;You are right in saying that's all that's needed, with the addition of a strategic or tactical need.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The need for a &quot;special evasion&quot; technique is only needed for aircraft dropping megaton range weapons in an air burst.  Kiloton range weapons could be dropped from altitude with no special evasion required except a lot of speed.  Sub-sonic aircraft would need to be &quot;frisky&quot; in their escape. Read about &lt;a href=&quot;//en.wikipedia.org/wiki/Tsar_Bomba&quot;&gt;Tsar Bomba&lt;/a&gt; for a good example which demonstrates that even with the biggest bomb ever dropped, a relatively slow, lumbering aircraft can escape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;//www.google.com/search?q=nuclear+weapon+helicopter&quot;&gt;Even helicopters can drop nukes.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft are only tasked to drop tactical, low yield weapons.  The real madness is assigned to subs and missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the comment above says, I suspect that most crews dropping strategic weapons will not care much whether they survive or not.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="923" LastEditDate="2015-04-27T03:11:50.160" LastActivityDate="2015-04-27T03:11:50.160" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="14398" PostTypeId="2" ParentId="11827" CreationDate="2015-04-26T22:48:59.313" Score="5" Body="&lt;p&gt;As an airline pilot (and test pilot) I like to keep my airplane under control (like all other airline pilots do). There is Boeing school and the Airbus school. Boeing airplanes will warn you not to get into those envelopes. Airbus won't allow you to get in that regime (envelope protection). In any case you can override that by changing law or disconnecting flight computers. In extreme cases where the situation is desesperate, I won't hesitate to overrule the computer and go into the extreme envelopes if I need to save lives. Bear in mind that everything in aviation is designed with a safety factor of 30% to 60% in some cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question: You are at FL370, sipping coffee, you have a fire on board. The aircraft limits your vertical speed and speed during descent (or bank angle if you want to turn back). Would you be OK with such limits? Myself, no. We are paid big bucks in the front to make decisions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second scenario (fake). FL340, cruise, your TCAS failed but you don't know (like I said it is fake scenario). Suddenly you see the other guy heading towards you. Same FL. But your computer says &quot;sorry you cannot pull hard because of the G protection&quot;, you hit the other guy: you are legally dead because you have not stressed the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last example: Just after departing for a 16-hour flight you have fire in cargo. The fire extinguishing systems are unsuccessful. You must land, but you cannot because you are overweight (by 100 tons I would say at least). What would you do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope I've triggered something about your question. BTW I'm on 777.&lt;/p&gt;&#xA;" OwnerUserId="8283" LastEditorUserId="753" LastEditDate="2018-06-19T13:58:04.070" LastActivityDate="2018-06-19T13:58:04.070" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14399" PostTypeId="2" ParentId="14396" CreationDate="2015-04-26T23:46:54.773" Score="18" Body="&lt;p&gt;Simon's answer discusses technical requirements to deploy nuclear weapons on an aircraft. However, there are less-technical requirements as well. Specifically, for reasons that should be fairly obvious, countries are very concerned that the aircraft carrying their nuclear weapons &lt;em&gt;will not&lt;/em&gt; release an armed weapon when they aren't supposed to. At least for the US, just about anything involved with nuclear weapons has to be certified to ensure that it won't cause a nuclear accident. This involves &lt;em&gt;lots&lt;/em&gt; of failsafes; for instance, an aircraft must have a locking system which is entirely separate from the release mechanism and which physically restrains the release mechanism, so that &lt;em&gt;no&lt;/em&gt; failure in the release mechanism alone can result in release.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually complying with the requirements largely falls within a broadened version of &quot;electronics to deal with the bomb&quot; (it also has some additional mechanical stuff required, and certain preexisting parts may need additional failsafes added, but it's in the spirit of that question, and in any case it's not &lt;em&gt;that&lt;/em&gt; expensive). However, certification and preparation of the Typhoon would involve US personnel learning lots of technical details of the plane, which Eurofighter would rather the US didn't (after all, they want to export Eurofighter). This isn't an issue for most munitions, because normally a country owns the weapons it deploys; nuclear weapons in Germany are different, because Germany is a non-nuclear weapons state that is forbidden from having nukes in peacetime under the Nuclear Nonproliferation Treaty. Nukes in Germany are under US control, and Germany only gets to deploy them if the US lets them during a war, so US regulations apply, and the added requirement is &quot;a nuclear weapons state lets you use their bombs.&quot; In addition, there's a requirement of &quot;the government is willing to carry nukes;&quot; if the German government decides they don't like the idea of carrying nukes in wartime, the plane won't get the needed modifications.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-04-26T23:46:54.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14400" PostTypeId="2" ParentId="11827" CreationDate="2015-04-27T00:09:18.190" Score="0" Body="&lt;p&gt;About the AF accident. The basic of flight: PITCH, POWER, PERFORMANCE. Meaning that when something is wrong you disconnect all automation and get manual control of the ship. The key beyond the PPP is that for almost any given situation applying a pitch, a power setting and a configuration (flaps, slats, gear....) you will kee you flying. With automation those things are long gone. During a flight, each hour I was writting down power setting, wind direction, temperature (among fuel and other legal stuff). Those whom started flying without autothrust and on turbo props know what it s like.&lt;/p&gt;&#xA;" OwnerUserId="8283" LastActivityDate="2015-04-27T00:09:18.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14401" PostTypeId="2" ParentId="11827" CreationDate="2015-04-27T00:51:00.133" Score="1" Body="&lt;p&gt;Generally limiters are optimized and designed to fulfill a specific function or role relation such as the Airbus full stick aft to achieve max AoA during terrain avoidance. However, not all limiters are foolproof, despite what is advertised by the manufacturers. Limits can be exceeded depending on how the limiter functions and FCS are implemented eg using dynamic manoeuvres such as repeated pushing and pulling at reasonant frequency or sudden manoeuvres at speeds for which the FCS wasn't designed for or in degraded aircraft modes. Although these possibilities exist, they are usually not relevant because these are corner cases unlikely to be encountered. &lt;/p&gt;&#xA;" OwnerUserId="8030" LastActivityDate="2015-04-27T00:51:00.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14402" PostTypeId="1" CreationDate="2015-04-27T01:07:58.230" Score="1" ViewCount="195" Body="&lt;p&gt;My google-fu is failing me here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A friend was telling me about the assembly of carbon-fibre planes, and how the huge parts of these need to be transported long distances between countries. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any photos of this?&lt;/p&gt;&#xA;" OwnerUserId="3049" LastActivityDate="2015-05-02T01:51:12.197" Title="Are there pictures of unassembled planes being transported around?" Tags="&lt;aircraft-manufacturer&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-05-02T11:51:57.820" ContentLicense="CC BY-SA 3.0" />
  <row Id="14403" PostTypeId="2" ParentId="14396" CreationDate="2015-04-27T04:24:15.787" Score="9" Body="&lt;p&gt;What neither of the other answers have touched on is the real reason why some aircraft can be used to deploy nuclear weapons and other can't.&lt;br/&gt;&#xA;And that is the special equipment needed on board these aircraft to carry, arm and and launch the weapons. Which is a big reason not just why some aircraft can and others can't deploy nuclear weapons but pretty much any weapon.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;It's not as if you can just bolt a bomb or missile to an aircraft, you need the correct connectors/clamps to attach it to, you need the right electrical, mechanical, and/or electronic equipment to arm it, give it guidance information if applicable, things like that.&lt;br/&gt;&#xA;And in case of nuclear weapons there are safeguards built in that require a very special set of equipment to operate and enter launch codes (in the first generations of nuclear weapons it even required a crew member to crawl into the bomb bay of the aircraft in flight to insert the trigger mechanism into bomb by hand).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;While the connectors on the launch rails have in part been standardised across fleets, there are still differences, and in guidance systems there are of course far more differences still (to launch an AMRAAM you of course will need different data to the missile than to launch a Harpoon for example).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-04-27T04:24:15.787" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14404" PostTypeId="1" AcceptedAnswerId="14413" CreationDate="2015-04-27T05:59:58.467" Score="2" ViewCount="633" Body="&lt;p&gt;Many airlines are toying with the idea of getting rid of seat-back displays, how much revenue did those seat-back displays bring in the form of in-flight advertisement? I would presume for a long haul flight the revenue might be more than what it is for a mid-range flight.&lt;/p&gt;&#xA;" OwnerUserId="8287" LastEditorUserId="1696" LastEditDate="2015-04-27T14:47:55.030" LastActivityDate="2015-04-27T15:46:47.460" Title="How much revenue do seat-back displays generate?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14405" PostTypeId="1" AcceptedAnswerId="20783" CreationDate="2015-04-27T06:14:21.557" Score="15" ViewCount="1404" Body="&lt;p&gt;Does professional ATC RADAR simulator software need to comply to some regulations or requirements in order to be used for real life controller training?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have ICAO, Eurocontrol, EASA or FAA published any such regulations or requirements in their documents? If so, any reference to a document is appreciated.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="64" LastEditDate="2016-07-07T21:05:58.103" LastActivityDate="2019-10-04T11:14:04.863" Title="What regulations exist for ATC real time RADAR simulator software?" Tags="&lt;air-traffic-control&gt;&lt;regulations&gt;&lt;software&gt;&lt;atc-simulator&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14406" PostTypeId="2" ParentId="14402" CreationDate="2015-04-27T08:28:04.553" Score="4" Body="&lt;p&gt;Here you have pictures of wing upper cover being handled and transported:&#xA;&lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/the-first-a350-xwb-wing-upper-cover-is-en-route-to-airbus-wing-assembly-plant-in-broughton-uk/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/wlIyK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;/a&gt;&#xA;&lt;sup&gt;(Image Source: www.airbus.com)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing upper cover is biggest single composite component on A350XWB.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionaly try google: &quot;wing upper cover A350&quot;, &quot;wing lower cover A350&quot;. Those are the biggest. And you can see them in various stages in google.&lt;/p&gt;&#xA;" OwnerUserId="4420" LastEditorUserId="572" LastEditDate="2015-04-27T09:01:51.553" LastActivityDate="2015-04-27T09:01:51.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14407" PostTypeId="1" AcceptedAnswerId="14420" CreationDate="2015-04-27T13:20:58.183" Score="11" ViewCount="13927" Body="&lt;p&gt;Both the &lt;a href=&quot;http://www.garmin430.com/&quot;&gt;GNS430&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Garmin_G1000&quot;&gt;G1000&lt;/a&gt; are/were available with and without &lt;a href=&quot;http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System&quot;&gt;WAAS&lt;/a&gt;, and I believe it's even possible to upgrade a GNS430 to add WAAS support. When I get into an unfamiliar rental aircraft, is there a quick and easy way to see if WAAS is available, by checking the avionics themselves? Is anything physically different about the units, is there some properties/status page I can check, or is there something different on the display?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously asking the operator and checking the aircraft handbooks would be the right thing to do, but sometimes that doesn't work out, e.g. the FBO's instructors are all out flying and the admin people just don't know.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="12720" LastEditDate="2016-03-21T09:58:26.237" LastActivityDate="2016-03-21T09:58:26.237" Title="How can I tell if a G430 or G1000 has WAAS or not?" Tags="&lt;avionics&gt;&lt;gns430&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14409" PostTypeId="1" CreationDate="2015-04-27T14:56:04.177" Score="4" ViewCount="837" Body="&lt;p&gt;Could a bird-sized consumer drone be digested by a jet engine, and not be recognized as a drone, mistaking it as a bird strike? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking of the situation during the flight - like an engine making a short unusual noise, but works OK; not sure that can even happen eating a small bird?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As was pointed out, the debris of the object will look different in obvious ways when checking the engine after flight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would assume a major factor is how the engine handles the drone, in terms of defects or running anomalies.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The battery comes to mind, hitting a turbine blade might be a problem - depending on the battery size.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are certainly drones with very small batteries, that I assume will do no obvious harm, and certainly ones with batteries big enough to do harm for sure.  &lt;/p&gt;&#xA;" OwnerUserId="1875" LastEditorUserId="995" LastEditDate="2015-10-21T22:42:32.230" LastActivityDate="2015-10-21T22:42:32.230" Title="Can a drone hitting a plane be mistaken for a birdstrike?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;unmanned-aerial-vehicle&gt;&lt;birds&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14410" PostTypeId="2" ParentId="14379" CreationDate="2015-04-27T15:24:32.753" Score="2" Body="&lt;p&gt;Is it realistic... No...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in the other answer the first main gaps are the HUD which an SR22 does not have to my knowledge and the flight dynamics which don't seem real. But keep in mind that google most like had a few people make this as a fun little addition to google earth I don't think its intended to be a realistic simulator. I am a pilot and a big fan of simulators as they are a great tool but they are just that, a &lt;em&gt;tool&lt;/em&gt;. The flight dynamics in Google Earth are not what they would be in a real plane and I would never expect that. There are lots of issues with home based simulators and realism. There are full moving sims out there for pros but in the home market, unless you are &lt;a href=&quot;https://www.youtube.com/watch?v=J5BmA3ejyHY&quot; rel=&quot;nofollow&quot;&gt;this guy&lt;/a&gt; you are only going to get so much realism.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Movement&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the sim has basic pitch up and down, bank and roll functions it does not feel anything like flying a real plane. Your desk chair is not going anywhere. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flight Dynamics&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have not flown an SR22 yet but I would imagine they dont handle like they do in that sim. There are other simulators out there (X plane) that have the ability to make very real simulations. Your seat will never move but the flight dynamics of the plane are close to the real thing and good for practice. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Control Input&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A real plane is not flown with a keyboard... Yet... but if you do have a joystick or yoke you can get somewhat of a feel for real planes. The issue is that your home yoke will not provide the feedback a real plane does (at least a small plane). I fly the Piper Warrior and before trim there is quite a bit of force on the controls, more than the little springs in my yoke provide. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;View&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unless you have a bunch of monitors you will never see in a sim what you see in real life. In a real plane you can see all around you, but you need to keep in mind you are playing a game not flying a real plane. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Its a tool&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Simulators are great tools, they can provide a great platform to train in and get to know the systems of a plane and how they work. However they will never (at least not now) replace real flying no matter how hard you try. Sim's strive for realism but they are in the end of the day a simulation of a physical experience and nothing more. The Google Earth Sim was clearly put together to be more fun than real. The runway roll was almost non existant and a single click of the up arrow put me in a stall which is clearly not realistic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to see how close it is, go to your local airport and see if they have a flight school that offers an intro course. You can get behind the controls of a real plane and see for yourself! &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-27T15:24:32.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14411" PostTypeId="1" AcceptedAnswerId="14414" CreationDate="2015-04-27T15:27:08.157" Score="10" ViewCount="1222" Body="&lt;p&gt;I am considering enrolling in a PPL course, and am getting information about the flight schools in my city (Rome, Italy).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What should I be looking for?&lt;/li&gt;&#xA;&lt;li&gt;How can I choose among them?&lt;/li&gt;&#xA;&lt;li&gt;Their fees differ by at least €3000. Are there differences between the schools that justify such different prices?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="705" LastEditorUserId="705" LastEditDate="2015-04-28T08:21:08.370" LastActivityDate="2016-03-18T16:23:34.900" Title="How to choose a flight school?" Tags="&lt;flight-training&gt;&lt;flight-school&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14412" PostTypeId="2" ParentId="14411" CreationDate="2015-04-27T15:38:44.383" Score="4" Body="&lt;p&gt;Your question is a nice but at the same time, very broad. It is similar to &lt;a href=&quot;https://aviation.stackexchange.com/q/9869/65&quot;&gt;What to look for in a flight instructor?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've pointed out some resources which provide very valuable information about the topic. However, please keep in mind that the most important factor is how quickly you can master a particular tasks of flight training. The question I referenced above will answer your next question once you settle down with a flight school.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aopa.org/letsgoflying/ready/choose/howto.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;How To Choose A Flight School / Flight Instructor&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://academy.aerosim.com/choose-flight-school-aviation-career&quot; rel=&quot;nofollow noreferrer&quot;&gt;How to Choose a Flight School for an Aviation Career&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.pilottricks.com/i-just-want-to-learn-to-fly-for-fun/step-3-choose-your-flight-school/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Choose Your Flight School&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.wikihow.com/Pick-a-Flight-School&quot; rel=&quot;nofollow noreferrer&quot;&gt;How to Pick a Flight School&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Good luck in following your dream.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-04-27T15:38:44.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14413" PostTypeId="2" ParentId="14404" CreationDate="2015-04-27T15:46:47.460" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;http://skift.com/2014/09/18/aviation-tech-giants-join-forces-to-increase-airline-seat-revenue/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; from September 2014:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Thales estimates total revenue from IFE at \$17.6m a year for&#xA;  small/mid-sized carriers, up to \$397m a year for large carriers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But that's for all services, not just advertising. The only specific mention I could find of advertising was &lt;a href=&quot;http://airfax.com/blog/index.php/2012/11/20/how-much-money-has-your-ife-made/&quot; rel=&quot;nofollow&quot;&gt;this 2012 quote&lt;/a&gt; attributed to the CEO of &lt;a href=&quot;http://www.thompsonaerospace.com/&quot; rel=&quot;nofollow&quot;&gt;Thompson Aerospace&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Somewhere in the middle of the second question about advertising on&#xA;  the system he said: “… and we are generating somewhere between \$20,000&#xA;  and \$30,000 per month per plane with the IFE.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The revenue is apparently generated in a similar way to internet advertising:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] every 2 weeks the airline and the advertising service bureau receives&#xA;  a summary of the requests/viewings and the airline gets a check. At 1&#xA;  to 5 cents per click, the tally adds up as daily flights, sometimes&#xA;  short as an hour, record revenue and usage every passenger, every&#xA;  flight, every day, and every month&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, there's no information in the article about which airlines actually use that specific service, and I have no idea if those numbers are typical or not, or even exaggerated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need more information than that and you can afford USD 4,650 to find out, &lt;a href=&quot;http://www.marketsandmarkets.com/Market-Reports/in-flight-entertainment-communications-market-860.html&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; looks like a comprehensive report on the IFE industry.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-04-27T15:46:47.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14414" PostTypeId="2" ParentId="14411" CreationDate="2015-04-27T16:07:41.123" Score="12" Body="&lt;p&gt;I'm not sure how it works in the EU as I am an American PPL student but let's ignore the small specifics and look at some general points. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Number of planes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where I fly there are 2 flight schools; one has a fleet of about 20 planes from Grumman trainers all the way up through a Seminole. The other school has 2 planes... The obvious thing here is down time. The fact is that planes break, need routine checks and get rented by other students. A flight school with more planes (and an appropriate amount of instructors) will be able to handle these issues better. Many times I have booked a plane to find that it's in the shop and I get assigned another plane (same make and model). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Type of planes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you cant be as picky here since sometimes geography limits you, some schools may be significantly more expensive than others. One of the nearby fields flight schools I looked at had just bought a new fleet of SR22's and were renting them at 250 USD an hour wet compared to the 100 USD an hour wet that I pay for a Piper Warrior. This can make a big difference in cost of training. Not that you are thinking this far in advance but if you do intend to one day buy a plane you may want to consider training in the type although its hard to say what kind of plane you would buy before you start flying :). If you intend on getting your instrument rating (I assume there is an EU equivalent) you will also want to make sure you are at a place that has instrument-capable planes and possibly even a precision approach system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also stands to reason that a place with older planes may see more down time as the planes may need more service but most old planes that I have flown are well kept. Here in the US trainer planes need to be inspected every 100 hours so they are out somewhat frequently for that already.     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Number of instructors&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here in the US many instructors are doing so to get enough hours for their ATP. With that in mind instructors are subject to leave at any time if they make their hours and find a commercial job. Bigger schools will be able to reassign you to another instructor or may have better luck hiring a new instructor to fill the gap. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Type of airport&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again sometimes you can't be picky here because of geography but training at a towered airport as apposed to an uncontrolled field can help you hone in your radio work from day one. A bigger slightly more busy airport may also give you real experience with things like wake turbulence avoidance. Most larger airports also tend to have 2 runways which can help you on those windy days (depending on direction and such). They also tend to have better services like plowing, precision approaches, fuel (not all airports have gas!), pre-heats that don't take 20 minutes to show up etc. This can also be a but of a curse sometimes as larger airports are subject to traffic and you may find your self sitting on the runway waiting to take off on a nice day. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cost&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be a big factor for some people. Some are lucky enough to have the money to fly where its easiest for them (close to home or work) etc., while others don't have this luxury and must fly where its the cheapest. Here in the US a cheap school will still get you the same PPL that a super expensive place with a brand new SR22 will. So if your goal is simply to fly and cost is a serious factor there is nothing wrong with going with the cheaper option (which may involve driving a bit farther) as long as you factor in the potential down time of the planes or difficulty of booking them.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-18T16:23:34.900" LastActivityDate="2016-03-18T16:23:34.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14415" PostTypeId="2" ParentId="14409" CreationDate="2015-04-27T17:47:26.980" Score="6" Body="&lt;p&gt;A small drone, like those commercially available, is not much bigger than your average raptor or even a goose, but the material it's made of is much harder. Not very many geese have aluminum shoulders affixed with stainless-steel screws and supporting carbon-fiber wing struts. As such, a drone will do much more damage to the turbine blades (or the windshield or any other leading surface). This is one of the big reasons for current restrictions on UAV operations; current rules treat them similarly to model aircraft, and that means a ceiling of 400 feet and a no-go zone five miles from any controlled airspace unless you have comms with the tower for the space you enter.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-04-27T17:47:26.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14416" PostTypeId="2" ParentId="14381" CreationDate="2015-04-27T18:18:57.137" Score="3" Body="&lt;p&gt;A stall, technically, is a departure of turbulent airflow over the top of the wing due to an extreme angle of attack. When this happens the wing no longer generates lift as designed. In most &quot;everyday&quot; aircraft scenarios the most common reason for a stall is a combination of insufficient speed and too high a nose pitch. Aerobatic aircraft including fighter jets can encounter stall scenarios in other ways, including intentionally (several maneuvers involve intentional stalls; the 3-D equivalent of intentionally entering a skid in a car).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When taking off, an aircraft typically does not exceed the maximum angle of attack for its current speed; if it did, the aircraft would stall and likely crash. The aircraft instead accelerates to a speed in excess of the forward stall speed of the aircraft, and then gently pitches upward to gain altitude. To the average passenger, especially a first-timer, it may not look or feel &quot;gentle&quot; to have the aircraft pitch 15-20 degrees up in the air, but during that maneuver the AOA remains very shallow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To assist heavier aircraft (or those designed for faster cruise speeds) in getting off the ground quickly and/or at a lower speed, the flaps can be positioned in a moderate setting, often specifically designated as a &quot;take-off&quot; setting, to increase the lift the wing generates at lower speeds. This happens through a combination of increasing the effective upper surface of the wing, and also directing the airflow leaving the wing downwards. In a &quot;clean&quot; configuration (the most aerodynamic setup for cruising, which includes no flaps), the minimum speed at which the wing can still generate lift will be higher.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-04T23:44:04.437" LastActivityDate="2015-05-04T23:44:04.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14418" PostTypeId="2" ParentId="9325" CreationDate="2015-04-27T18:44:10.173" Score="2" Body="&lt;p&gt;Define &quot;modern&quot;. The A-10 is only 38 years old, is still in service and is expected to remain so until at least 2020 (its planned replacement, along with many other current service aircraft including the F-15E, F-16 and F/A-18, is the much-maligned F-35 program). It has redundant hydraulic systems for all major control surfaces, plus a set of drect cable linkages, so even in a fully unpowered glide a true &quot;dead stick&quot; landing is possible. However, this is probably an unfair example as the A-10 was designed in part for extreme survivability in low-altitude combat conditions where the aircraft could encounter practically everything that airplanes and their pilots don't like, from small-arms fire and flak to short-range ground or air missiles and even a well-aimed tank or artillery round.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Modern&quot; fly-by-wire jets typically have similar redundancy, but with no direct mechanical link from stick to control surfaces, they are at least partially dependent on electrical power for the flight control computer (in addition to the power required for the hydraulic motors). In the case of a total loss of electrical power, you're right, the aircraft would be uncontrollable until one of two things happened; the pilot got one of the electrical sources back online (typically an engine-powered generator), or he gave up and punched out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One might wonder how much has to go wrong for the generator coupled to each engine turbine &lt;em&gt;and&lt;/em&gt; the APU to fail, leaving the pilot with only battery power for the displays (and to attempt maybe one engine restart). The answer is &quot;a lot&quot;; the most likely scenario causing a simultaneous failure of all generation systems is a missile impact, and in that scenario most fighters wouldn't make it back anyway. However, a failure in the power &lt;em&gt;distribution&lt;/em&gt; system of the aircraft might be more likely; this system is redundant as well, but there are some necessary bottlenecks, and one or two relatively minor failures in series could conceivably disable a plane mid-flight.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-04-27T19:44:22.890" LastActivityDate="2015-04-27T19:44:22.890" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14419" PostTypeId="2" ParentId="14249" CreationDate="2015-04-27T19:48:52.297" Score="2" Body="&lt;p&gt;In France pilots and ATC have to speak french if they are French&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is described in the radiotelephony procedure &#xA;&lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/dossier/texteregle/RADIOTEL_V2.pdf&quot; rel=&quot;nofollow&quot;&gt;https://www.sia.aviation-civile.gouv.fr/dossier/texteregle/RADIOTEL_V2.pdf&lt;/a&gt;&#xA;section 2.4&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2.4 Use of French language:&#xA;  The French language is used (except for training purposes or particular cases) between French pilot and ATC&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The rules of air indicates that the ATC must be able to speak english if they have to deal with international traffic. &lt;/p&gt;&#xA;" OwnerUserId="3277" LastActivityDate="2015-04-27T19:48:52.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14420" PostTypeId="2" ParentId="14407" CreationDate="2015-04-27T19:53:58.917" Score="7" Body="&lt;p&gt;&lt;em&gt;NOTE: as pointed out in the comments, none of these quick verification steps actually guarantees that the airplane you clambered into is certified for LPV approaches, or for IFR GPS usage at all!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On boot, a 430W will display that it's a 430W:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Py7DW.png&quot; alt=&quot;Garmin logo loading screen with model number&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from that, I'm sure there's a version info screen somewhere (on both G1000 and GNS430), but the best solution I can think of is to check the satellite status screen. I'm trying to find examples of a 430W displaying it, and failing, but on a G1000, you'll see this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://theflyingengineer.files.wordpress.com/2014/01/g1000_sbas02.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4DYW3m.jpg&quot; alt=&quot;G1000 screen with GPS info&quot;&gt;&lt;/a&gt; &lt;br&gt;&lt;sup&gt;(&lt;a href=&quot;http://theflyingengineer.com/2014/01/20/gagan-readiness-g1000-with-gia-63w-diamond-da40ng/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the G1000 supports WAAS, it'll display that under the 'SBAS Selection' header and you'll see satellites at the bottom numbered in the 100s - &lt;code&gt;124&lt;/code&gt;, &lt;code&gt;126&lt;/code&gt;, &lt;code&gt;129&lt;/code&gt;, etc - all the 100-series satellites are the WAAS augmentation satellites. The satellites augmented by WAAS will also have a &quot;D&quot; at the bottom of the signal strength column.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-04-27T21:10:19.507" LastActivityDate="2015-04-27T21:10:19.507" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14421" PostTypeId="1" CreationDate="2015-04-27T20:08:04.260" Score="0" ViewCount="2404" Body="&lt;p&gt;I want to build an rc plane that looks like this one&#xA;&lt;img src=&quot;https://i.stack.imgur.com/6WvGy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the general dimensions that I should follow? I dont want to copy other designs of real uav's and scale them down. A drawing would be great&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to build something small, wing span should be about 125 cm&lt;/p&gt;&#xA;" OwnerUserId="8127" LastEditorUserId="8127" LastEditDate="2015-04-27T20:21:54.170" LastActivityDate="2015-04-27T20:31:04.900" Title="General dimensions for a uav type rc plane?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-04-27T21:32:14.123" ContentLicense="CC BY-SA 3.0" />
  <row Id="14422" PostTypeId="2" ParentId="14421" CreationDate="2015-04-27T20:31:04.900" Score="1" Body="&lt;p&gt;You can start by looking at plans &lt;a href=&quot;http://www.rcfoam.com/free-rc-airplane-plans-a-free_rc_airplane_plans.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; to get a general idea. When it comes to planes you can't just get some &quot;general&quot; measurements and wing it (pun intended). There are a lot of considerations when it comes to making things fly. With out going into specifics it would be best to use known working plans to build something as apposed to trying to throw something together that looks right. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To Answer your question directly that picture looks like the wing span is the the 3.5 foot range, the center section is about 2.5 feet long and tail poles are about 18 inches. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-04-27T20:31:04.900" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14423" PostTypeId="2" ParentId="14354" CreationDate="2015-04-27T21:03:42.080" Score="13" Body="&lt;p&gt;There are very few mission profiles in modern (post-WWII) combat that call for &quot;carpet-bombing&quot; of the type that the WWII-era medium and heavy bombers were used for. The primary target of a strategic bombing campaign is typically a city or other highly-populated area. During WWII it was considered a necessary evil, as high-value military-industrial targets were typically located in these cities and the accuracy (and power) of bombs was sharply limited, usually requiring an entire wing of bombers to ensure complete destruction of the target. This approach has since has been eschewed as barbaric by nations with significant air forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technologically, advances have continued to chip away at the heavy bomber's mission profile. Small, precision bombing campaigns have always been given to light bombers like the Stuka, Mosquito and Mitchell, and in later eras the F-100 Super Sabre, F-105 Thunderchief (aka the Thud), A-6 Intruder and A-7 Corsair. These later aircraft used the development of the electronic fire control computer to dramatically increase the precision of unguided weapons, which along with their greater speed against enemy interceptor aircraft rendered the familiar sight of a sky darkened with large bombers unnecessary. In modern warfare, there are few dedicated small ground attack aircraft (the A-10 being a notable exception designed for close air support), most of that going to &quot;multirole&quot; aircraft such as the F-16 and F/A-18, with a few &quot;deep strike&quot; fighters like the F-15E (and when a similar mission profile but more firepower is called for, the B-1B finds its niche). These fighters handle the majority of offensive operations against high-value targets and enemy air defenses (&quot;Wild Weasel&quot; missions), with the A-10, AC-130 and Army helicopters handling the direct threats to infantry and armor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the early Cold War era, the best and biggest reason to keep heavy bombers like the B-29, B-48 and B-52 was that they were the only suitable vehicle for the delivery of strategic nuclear weapons (&gt;1Mt). These weapons were phased out of the U.S. arsenal with the introduction of the MIRV-capable ICBM, able to carry the same total payload much farther, faster and with less impact of attrition by defenses, and shortly afte the dissolution of the Soviet Union, the Strategic Air Command itself, the single largest operating authority of the B-52 in history, was dissolved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last big reason to have something like a B-52 in theater is the ability to loiter indefinitely (at least 24 hours at a stretch). B-52s have the size and crew space to allow for crew rotations (you're not going to find Stearns and Foster mattresses aboard, but there are a few places to stretch out and kip, and there is a crude lavatory known sarcastically as a &quot;honey bucket&quot;), and with in-flight refueling, the only serious limitations to flight time are the capacity for on-board food stores and the eventual depletion of munitions. The B-52 can be equipped with 336 GPS-guided JDAM weapons, and a B-52 loitering at 50,000 feet over a theater like Afghanistan can be directed via AWACS/JSTARS to drop a guided bomb at a target with no visual line-of-sight needed. If air defenses are a potential problem, it has far-BVR capabilities when using cruise missiles like the JSOW, though it can carry fewer of them. This is the B-52's last stronghold, and it's a significant one; given various upgrades for efficiency and technological improvement during its life, the USAF plans to maintain a modest number of these aircraft until at least 2040.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-24T19:43:46.783" LastActivityDate="2015-06-24T19:43:46.783" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14424" PostTypeId="2" ParentId="14409" CreationDate="2015-04-27T21:26:14.647" Score="9" Body="&lt;p&gt;Would one be able to tell the difference before landing?  Not likely in many scenarios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Case 1: Bird hits windshield: blood &amp;amp; guts are immediately visible.  Drone hits windshield, cracks are visible but not much else.  The crew CAN immediately figure out, if they've ever see a birdstrike on the windshield, that this was something else.  (Of course, it could just be a shattered outer pane -- those do fail sometimes, not necessarily due to any collision.  Never had one go in flight, so I don't know if the sound of the pane shattering might be mistaken for a collision {or vice-versa}, or not.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Case 2: Bird hits near the cockpit but NOT on a windshield.  Sounds like a sharp crack, like a piece of gravel hitting your automobile windshield at highway speeds.  If a drone did the same, it would probably sound pretty similar, and without the blood/guts to see (or not see), the ability to notice what's missing may not be there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Case 3: Bird hits the engine, and it starts running poorly. &lt;strong&gt;Sometimes&lt;/strong&gt; you will smell the guts cooking in the core of the engine (i.e. they get into the bleed air system &amp;amp; thus into the air conditioning), and that's a clear sign that your engine ate a bird.  But the bird CAN miss the core and still cause problems with the fan blades.  Most birds that miss the core are chopped up by the fan blades &amp;amp; the crew had no idea until after landing that anything happened, but a big enough bird can cause damage that way.  So if the engine starts running rough, hot, and with some vibration, the absence of &quot;cooked goose&quot; odor isn't &lt;em&gt;necessarily&lt;/em&gt; going to drive the conclusion that the collision had to be with something other-than-a-bird.  One might &lt;em&gt;suspect&lt;/em&gt; that a lot of damage with no smell seems unlikely to be a birdstrike, but there are cases where some engine component has failed &amp;amp; caused engine damage (ranging from barely noticeable up to catastrophic), and you can't really know much about causality for the engine doing what it's doing until you're on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, all of this assumes that the crew doesn't see the object that they hit.  Which they very well might.  Everything in that case is obviously an entirely different discussion.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-04-27T21:26:14.647" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14425" PostTypeId="1" AcceptedAnswerId="14433" CreationDate="2015-04-28T02:08:04.483" Score="8" ViewCount="726" Body="&lt;p&gt;I am trying to estimate the bank angle/turn radius required to lose a given amount of altitude during a full orbit. This has led me to trying to estimate glide ratio in proportion to $L/D_{MAX}$ of an aircraft in a balanced gliding turn, knowing only $V_{MD}$ and $L/D_{1g}$ for $V_{MD}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My approach is to use the following relationships:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$D = D_0 + D_I$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$D_{0} = C_{D_0} 0.5{\rho}v^2 S$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$D_I = C_{D_I} 0.5{\rho}v^2 S$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_{D_I} {\alpha} {C_L}^2 $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_L {\alpha} L $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L {\alpha} n $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$n = \frac{1}{cos({\phi})}$ (${\phi}$ = bank angle)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming $D_0 = D_I$ at $V_{MD}$ I think I should be able to calculate:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L/D_{n_g} = \frac{L/D_{1g}}{0.5 + 0.5(1/cos^2({\phi})}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since altitude lost in a full orbit becomes $\frac{2{\pi}r}{L/D}$ where r = turn radius and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$r = \frac{v^2}{g tan(\phi)}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Altitude lost in a full orbit should ${\alpha} \frac{1}{cos^2({\phi}) tan({\phi})}$ which looks like &lt;a href=&quot;https://graphsketch.com/?eqn1_color=1&amp;amp;eqn1_eqn=1%2F(tan(x)*cos(x)%5E2)&amp;amp;eqn2_color=2&amp;amp;eqn2_eqn=&amp;amp;eqn3_color=3&amp;amp;eqn3_eqn=&amp;amp;eqn4_color=4&amp;amp;eqn4_eqn=&amp;amp;eqn5_color=5&amp;amp;eqn5_eqn=&amp;amp;eqn6_color=6&amp;amp;eqn6_eqn=&amp;amp;x_min=0&amp;amp;x_max=1.57&amp;amp;y_min=0&amp;amp;y_max=50&amp;amp;x_tick=0.17453292519&amp;amp;y_tick=1&amp;amp;x_label_freq=5&amp;amp;y_label_freq=5&amp;amp;do_grid=0&amp;amp;do_grid=1&amp;amp;bold_labeled_lines=0&amp;amp;bold_labeled_lines=1&amp;amp;line_width=4&amp;amp;image_w=850&amp;amp;image_h=525&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;. Does my method look alright, or have I made any incorrect assumptions or errors?&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="19" LastEditDate="2016-07-14T07:45:37.143" LastActivityDate="2016-07-14T07:45:37.143" Title="How can the glide ratio in a balanced turn be estimated?" Tags="&lt;aerodynamics&gt;&lt;glide-ratio&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14426" PostTypeId="2" ParentId="10117" CreationDate="2015-04-28T04:05:49.177" Score="4" Body="&lt;p&gt;I fly a &quot;open cockpit&quot; flex-wing microlight.&#xA;I also wear an simple full face helmet that is separate to my headsets.&#xA;I fly relatively long flights with many being over 4 hours. &#xA;I have also flown for 15.5 hours in a single day in the microlight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passive headsets (from differing manufacturers) would often leave a ringing in my ears. After a flight, it would be a minute or two before I could actually hear people speaking to me.&#xA;R/T in flight was often difficult to hear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference an ANR headset makes at the end of a flight is night and day. &#xA;No ringing in the ears. Can hear people speaking to me fine.&#xA;ATC is heard loud and clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for hearing noise the aircraft engine makes, etc, ANR doesn't get rid of all noise, but it does stop you going deaf, so you can at least hear the subtle changes in the engines tone.&lt;/p&gt;&#xA;" OwnerUserId="8296" LastEditorUserId="4474" LastEditDate="2015-04-28T17:01:40.657" LastActivityDate="2015-04-28T17:01:40.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14430" PostTypeId="1" AcceptedAnswerId="14592" CreationDate="2015-04-28T18:28:54.610" Score="1" ViewCount="1809" Body="&lt;p&gt;I have made a GUI that allows the user to create waypoints defined by latitude, longitude, altitude, and time-of-arrival. I'm looking for some software that can generate a flightpath between the waypoints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, say that I have placed 5 waypoints. All that I know is that I want my aircraft to be at those five points in space at the times specified. To create my 'flightpath', I want to calculate the latitude, longitude, altitude, pitch, roll, yaw, and velocity of the aircraft as it moves from one waypoint to the next. I'd like to calculate those values for time intervals of, say, one second. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've made a hackish solution, but it isn't very realistic. Someone must have tackled this problem before. Does anyone have any suggestions on software or algorithms I can use?&lt;/p&gt;&#xA;" OwnerUserId="8302" LastEditorUserId="97" LastEditDate="2015-04-29T20:12:11.223" LastActivityDate="2016-10-29T11:10:56.990" Title="How can I calculate a flightpath given a set of waypoints?" Tags="&lt;navigation&gt;&lt;flight-planning&gt;&lt;software&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14431" PostTypeId="2" ParentId="1464" CreationDate="2015-04-28T18:37:43.920" Score="4" Body="&lt;p&gt;The Doc4444 (google it) is the bible of air traffic control. It is the base for all international standards of separation, and in section 7.9.1 &quot;Separation of landing aircraft and preceding landing and departing aircraft using the same runway&quot; we read:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except as provided in 7.10 and Chapter 5, Section 5.8, a&#xA;landing aircraft will not normally be permitted to cross the&#xA;runway threshold on its final approach until the preceding&#xA;departing aircraft has crossed the end of the runway-in-use, or&#xA;has started a turn, or &lt;strong&gt;until all preceding landing aircraft are&#xA;clear of the runway-in-use.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now there are some national deviations from this in for example the US, but the basic principle is for a controller to NOT put him/her self in a monitoring situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the controller were to clear nb2 for landing while nb1 is still on the runway, and something happens to nb1 that unables nb1 from vacating the runway, the controller is in a hurry to &lt;strong&gt;restore&lt;/strong&gt; separation by cancelling the landing clearance to nb2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the controller instead follow the doc4444 and don't clear nb2 for landing, and something happens to nb1, the controller can do whatever he needs to do to help nb1 (send out fire trucks or whatever the problem demands), and IF the controller forgets to instruct nb2 to go around, that should be the default behavior of nb2 anyways since he never got a clearance to land (if no landing clearance is received when reaching the &quot;missed approach point&quot; the pilot will initiate a go-around). That way, &lt;strong&gt;separation was maintained the whole time&lt;/strong&gt; and needed not to be restored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers are trained to always take risk into consideration, and eliminating it whenever possible. In the case of your cessna, depending on the experience of the pilot (many small planes are flying for schooling purposes) he may not touch down in the touchdown zone, especially if there is a crosswind. Students sometimes make a few bounces before settling on the runway etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your reasoning saying that &quot;there would be more than enough space&quot; could also be used to argue for allowing a departure with a smaller aircraft when a larger one is way down the other end of the runway, &quot;the little one would be airborne long before the big one anyways&quot;, right? But a controller will think &quot;IF the little one has an engine failure (yeah, the small ones usually only have one engine...) on initial climb, he will glide back down on the runway. So we don't allow any type of obstacle on the runway in front of a departure either, no matter the size =)&lt;/p&gt;&#xA;" OwnerUserId="8303" LastActivityDate="2015-04-28T18:37:43.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14433" PostTypeId="2" ParentId="14425" CreationDate="2015-04-28T19:57:45.887" Score="9" Body="&lt;p&gt;I get a variation of the glide ratio with $\frac{2}{\bigl(\cos\varphi + \frac{1}{\cos\varphi}\bigr)}$ for circles flown with a bank angle of $\varphi$ when compared to straight flight at the respective best speed for optimum L/D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your initial assumptions are right:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift: $L = c_L\,\rho\,\frac{v^2}{2}\, S\, n_z$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Load factor: $n_z = \frac{1}{\cos\varphi}$ with the bank angle $\varphi$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag: $D = D_0 + D_i = \Bigl(c_{D0} + \frac{c_L^2}{\pi\, AR\,\varepsilon}\Bigr)\,\rho\,\frac{v^2}{2}\, S$ (zero-lift drag + induced drag), and both are equal at optimum $L/D$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\Bigl(\frac{L}{D}\Bigr)_{\rm opt} = \Bigl(\frac{c_L}{c_D}\Bigr)_{\rm opt} = \frac{\pi\, AR\,\epsilon}{2\, c_L}\text{ for straight flight at }1\, g \text{ ($n_z = 1$)}.$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now with load factor $n_z = n$ and unchanged speed:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{L_{ng}}{D_{ng}} = \frac{\frac{c_{L_{1g}}}{\cos\varphi}}{\frac{c_{L_{1g}}^2\bigl(1 + \frac{1}{\cos^2\varphi}\bigr)}{\pi\, AR\,\epsilon}} = \frac{\pi\, AR\,\varepsilon}{c_{L_{1g}} \bigl(\cos\varphi + \frac{1}{\cos\varphi}\bigr)}.$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ratio between both glide ratios is $\frac{2}{\bigl(\cos\varphi + \frac{1}{\cos\varphi}\bigr)}$, which makes sense because it will become 1 for $\varphi = 0$ and become less than 1 for nonzero values of $\varphi$. Note that the glide ratio at n g doesn't carry an &quot;opt&quot; subscript anymore, because by increasing $c_L$ we move away from the optimum. If the best L/D would be maintained for circling flight, speed would need to increase, not lift coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude loss in straight flight of a distance equal to the diameter of a circle with the radius $R = \frac{v^2}{g\tan\varphi}$ is $2\,\pi\, R \, \frac{D}{L}$. When flown at the correct bank angle, this altitude loss per circle $\Delta h$ will become&#xA;$$\Delta h =  \frac{\pi\, v^2}{g \tan\varphi} \Bigl(\frac{D}{L}\Bigr)_{1g}\Bigl(\cos\varphi + \frac{1}{\cos\varphi}\Bigr).$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plot of the glide ratio with bank angle divided by the glide ratio for straight flight (blue line). I also added the altitude loss for a full circle (red line, Basis: $L/D = 18$ at 100$\,$m/s in straight flight), both for flight at constant speed and constant lift coefficient:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/tCZNq.png&quot; alt=&quot;Altitude loss over bank angle at constant speed (green line) and constant lift coefficient (red line)&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use the results from this plot with caution at higher bank angles: Lift would need to double at a bank angle of 60°, doubling $c_L$, so we fly much more slowly than any pilot would. The red line gives more realistic values, since here the aircraft speeds up for flying higher bank angles. Flying at constant speed gives less altitude loss simply because the circle becomes smaller than when flying at constant $c_L$. Note that for every meter flown the altitude lost is greater when flying at constant speed, indicated by the blue glide ratio degradation curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two factors conspire to increase aerodynamic losses when flying at constant speed with higher bank angles:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You need to create more lift, which causes higher induced drag, and&lt;/li&gt;&#xA;&lt;li&gt;Your optimum $L/D$ is at a higher speed when the bank angle increases, which again increases aerodynamic losses because you move away from the optimum.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If you try to express the altitude loss per circle $\Delta h$ as a function of $\varphi$, you will get a quadratic equation and two solutions, one high and one low bank angle:&#xA;$$\frac{\cos^2\varphi + 1}{\sin\varphi} = \frac{g\,\Delta h}{\pi\, v^2} \Bigl(\frac{L}{D}\Bigr)_{1g}.$$&#xA;Maybe MathSE can solve this algebraically; I would resort to iteration or tabulation here.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T19:27:30.283" LastActivityDate="2015-05-10T19:27:30.283" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14435" PostTypeId="1" AcceptedAnswerId="14451" CreationDate="2015-04-29T04:37:49.963" Score="10" ViewCount="16280" Body="&lt;p&gt;In my first flight lesson today, my instructor asked me to apply full carburetor heat when we had to reduce power to 1900 RPM in our Cessna 152.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was surprised by this as I didn't remember learning this in ground school, and I later checked the Jeppesen textbook I am using, and referring to the section on carburetor icing, I saw that when power is reduced below normal operating limits, full carb heat is recommended (must have missed it when studying the ground material).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that the cause of carb icing is the sudden drop in temperature in the venturi due to drop in pressure as the fuel speeds up. If I am reducing power, I am reducing fuel flow, so shouldn't this reduce the chances of icing? So my question is why is full carb heat recommended when decreasing power below normal operation?&lt;/p&gt;&#xA;" OwnerUserId="173" LastEditorUserId="247" LastEditDate="2015-05-03T18:16:39.967" LastActivityDate="2018-07-28T08:17:58.013" Title="Why is full carb heat recommended when reducing power below normal setting?" Tags="&lt;piston-engine&gt;&lt;aircraft-systems&gt;&lt;icing&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14436" PostTypeId="2" ParentId="14435" CreationDate="2015-04-29T06:09:45.187" Score="11" Body="&lt;p&gt;When you close the throttle for descent, the airflow is constricted.  This constriction is going to cool the air more than it is during cruise configuration, and may increase icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Operations/Winter-Flying-%282%29&quot;&gt;This AOPA document&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Throttle ice is formed at or near a partly closed throttle valve. The water vapor in the induction air condenses and freezes due to the venturi effect cooling as the air passes the. throttle valve.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-04-29T06:09:45.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14437" PostTypeId="1" AcceptedAnswerId="14453" CreationDate="2015-04-29T06:34:46.000" Score="29" ViewCount="3813" Body="&lt;p&gt;&lt;a href=&quot;http://www.theverge.com/2015/4/28/8511993/ipad-issue-grounds-american-airlines-737s&quot; rel=&quot;noreferrer&quot;&gt;I was amazed to read this&lt;/a&gt; which implies that a software failure on iPads caused departing flights to return to the gate.&lt;/p&gt;&#xA;&lt;p&gt;I used to be an avionics engineer up until a point before the current generation of consumer electronics and now develop &amp;quot;field&amp;quot; apps for phones and tablets.  I know two things to be true.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Consumer phones and tablets of all persuasions used in field applications have nowhere near the reliability of certified avionics.  I own an iPad, amongst many&#xA;other devices, and it does not get close to six nines reliability (as do&#xA;none of my other consumer devices).  In particular, since the latest iPad updates over the last year or two, it's been quite buggy.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The hardware is not designed and built to the standards required for avionics and, without appropriate hardware, the&#xA;software cannot be to aviation standards either.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I know that these devices have been certified for use and I know why and what they are used for but I thought they were only convenience devices.  It seems that they have become part of the safety chain.&lt;/p&gt;&#xA;&lt;p&gt;Are they MEL items?  Does anyone know what's really going on here?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-30T15:28:21.437" Title="Why did an iPad software failure cause a return to the gate?" Tags="&lt;faa-approval&gt;&lt;efb&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14438" PostTypeId="2" ParentId="14437" CreationDate="2015-04-29T07:57:47.160" Score="15" Body="&lt;p&gt;iPads are used so the flight charts and manuals are electronic instead of the old phonebook that had to be printed and distributed every few months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that without it the pilot has no up-to-date copy of the flight chart of the airport where he is trying to land which is a safety issue.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="1467" LastEditDate="2015-04-29T08:21:58.593" LastActivityDate="2015-04-29T08:21:58.593" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="14439" PostTypeId="2" ParentId="8165" CreationDate="2015-04-29T09:06:48.380" Score="0" Body="&lt;p&gt;Everyone&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fight Data recorder(FDR) and CVR(Cockpit Voice Recorder) are both present on the Cessna 560XL; The statement made by the authorities could:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Be true. But for that to have happened, the airplane would have to have both Circuit Breakers(CB) pulled out by someone. When pilots conduct their pre-flight checks lights would illuminate indicating the problem. Or.....&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is indeed part of a cover up. Several witnesses said they saw one engine on fire before the plane went down. Having an engine fire during a go-around maneuver inside clouds is something extremely difficult and the flying pilot could have lost situation awareness and became disoriented.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8310" LastEditorUserId="1467" LastEditDate="2017-03-14T13:25:03.313" LastActivityDate="2017-03-14T13:25:03.313" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14442" PostTypeId="1" CreationDate="2015-04-29T11:44:59.973" Score="5" ViewCount="2541" Body="&lt;p&gt;There are commonly &quot;NO STEP&quot; signs on airplanes where damage could be caused if a maintenance worker inadvertently put weight on a delicate part of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the grammar of this appears to be off. It should either be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No Stepping -- akin to No Smoking, as it is the activity that is prohibited&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Not a Step -- this is not a step (noun)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Does anyone have any sense of why the grammar of this sign is incorrect? What is the history of it? Does it hark back to the military?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="572" LastEditDate="2015-04-29T11:54:40.687" LastActivityDate="2015-04-29T11:54:40.687" Title="Why is &quot;NO STEP&quot; used instead of a grammatically correct spelling?" Tags="&lt;aircraft-maintenance&gt;&lt;livery&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-04-29T14:17:53.873" ContentLicense="CC BY-SA 3.0" />
  <row Id="14444" PostTypeId="1" AcceptedAnswerId="14447" CreationDate="2015-04-29T12:59:41.893" Score="19" ViewCount="16563" Body="&lt;p&gt;Different sources seem to have different opinions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_warning_lights#On_aircraft&quot;&gt;Wikipedia: Aircraft warning lights:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These lights include landing lights, red or white flashing beacons, wingtip strobes, and wingtip navigation lights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Beacons and strobes are flashing lights.&lt;/li&gt;&#xA;&lt;li&gt;Beacons may be red or white.&lt;/li&gt;&#xA;&lt;li&gt;Strobes are wingtip lights. I interpret this as strobes being directional while beacons cover 180°.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot;&gt;Aeronautical Information Manual (AIM), 4−3−23. Use of Aircraft Lights:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. An aircraft anti−collision light system can use&#xA;  one or more rotating beacons and/or strobe lights, be&#xA;  colored either red or white, and have different (higher&#xA;  than minimum) intensities when compared to other&#xA;  aircraft. Many aircraft have both a rotating beacon&#xA;  and a strobe light system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. Prop and jet blast forces generated by large&#xA;  aircraft have overturned or damaged several smaller&#xA;  aircraft taxiing behind them. To avoid similar results,&#xA;  and in the interest of preventing upsets and injuries to&#xA;  ground personnel from such forces, the FAA&#xA;  recommends that air carriers and commercial&#xA;  operators turn on their rotating beacons anytime their&#xA;  aircraft engines are in operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Beacons are rotating lights. They're always referred as &lt;em&gt;rotating beacons&lt;/em&gt; in the AIM.&lt;/li&gt;&#xA;&lt;li&gt;Both beacons and strobes can be either red or white.&lt;/li&gt;&#xA;&lt;li&gt;I take the sentence &lt;em&gt;Many aircraft have both a rotating beacon&#xA;and a strobe light system.&lt;/em&gt; as beacons being the lower intensity lights which are constantly turned on during engine operation signalling the danger of an aircraft in operation, while the strobes being the higher intensity flashing ligths with the reason of being seen from great distance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Navigation_light#Aviation_navigation_lights&quot;&gt;Wikipedia: Aviation navigation lights&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft navigation lights are placed in a way similar to that of marine vessels, with a red navigation light located on the left wingtip leading edge and a green light on the right wingtip leading edge. A white navigation light is as far aft as possible on the tail or each wing tip.[3] High-intensity strobe lights are located on the aircraft to aid in collision avoidance.[4]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In civil aviation, pilots must keep navigation lights on from sunset to sunrise. High-intensity white strobe lights are part of the anti-collision light system, as well as the red rotating beacon.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All aircraft built after 11 March 1996 must have an anti-collision light system (strobe lights or rotating beacon) turned on for all flight activities in poor visibility. The anti-collision system is recommended in good visibility, where only strobes and beacon are required. For example, just before pushback, the pilot must keep the beacon lights on to notify ground crews that the engines are about to start. These beacon lights stay on for the duration of the flight. While taxiing, the taxi lights are on. When coming onto the runway, the taxi lights go off and the landing lights and strobes go on. When passing 10,000 feet, the landing lights are no longer required, and the pilot can elect to turn them off. The same cycle in reverse order applies when landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Beacons are red rotating lights.&lt;/li&gt;&#xA;&lt;li&gt;Strobes are high-intensity white lights.&lt;/li&gt;&#xA;&lt;li&gt;Beacons stay on for the duration of the flight including the whole engine run time.&lt;/li&gt;&#xA;&lt;li&gt;Strobes are added from takeoff until leaving the runway after landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is there a clear definition?&lt;/p&gt;&#xA;" OwnerUserId="8312" LastEditorUserId="340" LastEditDate="2015-04-29T14:26:47.020" LastActivityDate="2015-04-30T13:15:15.823" Title="What exactly distinguishes a beacon light from a strobe light?" Tags="&lt;avionics&gt;&lt;aircraft-lighting&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14445" PostTypeId="2" ParentId="14437" CreationDate="2015-04-29T13:05:51.743" Score="4" Body="&lt;p&gt;Nobody knows exactly what happened, but as far as I can understand the limited information available, this is what happened: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These iPads are used to carry map data that the pilot needs, and which used to come in the form of forty pound of paper. That data needs to be updated from time to time, and it is supposed to be updated through WiFi automatically when the pilot is in the cockpit at an airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That automatic update didn't work for some reason. The pilot found that the map data wasn't up-to-date and therefore wouldn't take off. Instead he took the iPad and carried it into the airport, where the map update worked without problem and then he took off with an iPad with good map data, with a delay. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it seems  that this was highly inconvenient, but not a security risk, assuming that the pilot used his checklist as he should. And the co-pilot had exactly the same problem with a second iPad, and fixed it the exact same way by carrying it to the airport. So it is unlikely to be a problem with that iPad. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. These iPads can be connected to power in the cockpit, so there is no fear that their battery power would run out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. Both pilot and copilot have an iPad, and they really only need one, so you could count that as backup. I read (but I have no idea if it is true) that there is supposed to be a third set of the maps for the airplane as well, so one set for pilot, copilot, and airplane each. &lt;/p&gt;&#xA;" OwnerUserId="7078" LastActivityDate="2015-04-29T13:05:51.743" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14447" PostTypeId="2" ParentId="14444" CreationDate="2015-04-29T13:58:42.300" Score="11" Body="&lt;p&gt;I think there are two points in your question: what is the &lt;em&gt;physical&lt;/em&gt; difference between a beacon and a strobe, and what is the &lt;em&gt;operational&lt;/em&gt; difference? For the rest of this answer, I'm going to assume that you're asking about an aircraft that has both a beacon and strobes; as you quoted above, it's possible for an aircraft to have neither. I'm also going to assume you're asking for an answer that applies in the US; regulations in other countries may be different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the physical difference is exactly what you've already determined: a beacon is a (relatively) low-intensity rotating red or red/white light; a strobe is a high-intensity flashing white light. (As noted in the comments below, some beacons flash instead of rotating, but they're still lower intensity than a strobe.) This isn't formally defined anywhere (e.g. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 1.1&lt;/a&gt; doesn't define them) but the information you found in the AIM is exactly how everyone I know uses the terms. It's also how you find those words used on aircraft part sites, e.g. &lt;a href=&quot;http://www.aircraftspruce.com/search/search.php?s=beacon&amp;amp;x=0&amp;amp;y=0&quot; rel=&quot;noreferrer&quot;&gt;beacons&lt;/a&gt; and &lt;a href=&quot;http://www.aircraftspruce.com/search/search.php?s=strobe&amp;amp;x=0&amp;amp;y=0&quot; rel=&quot;noreferrer&quot;&gt;strobes&lt;/a&gt;. So whatever the 'strict' definition might be, the practical and accepted one is exactly what you've found out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the operational difference essentially comes down to the question &quot;when do I have to turn them on?&quot; and in addition to what you found in the AIM the FAA gave more details as part of &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2011/murphy%20-%20%282011%29%20legal%20interpretation.pdf&quot; rel=&quot;noreferrer&quot;&gt;this legal interpretation&lt;/a&gt;. The questioner asked two questions about beacons and strobes: when to turn them on, and if they both have to be turned on. The key regulation quoted is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.3.7.5&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.209&lt;/a&gt;, and note that the FAA considers the beacon and the strobes &lt;em&gt;together&lt;/em&gt; to form a single &quot;anticollision system&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] it appears that the strobe light and the rotating beacon are&#xA;  part of the same anticollision system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When to turn them on:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;91.209(b) requires that an aircraft's anticollision lights be turned&#xA;  on once that aircraft's engine is started for the purpose of air&#xA;  navigation. As a safety precaution, the anticollision lights should be&#xA;  on before starting an engine or causing a propeller or rotor to move.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If both have to be turned on:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] because section 91.209(b) does not contain an exception for&#xA;  alternative sources of anticollision lighting, turning on the&#xA;  anticollision beacon would not relieve a pilot from the requirement to&#xA;  turn on the anticollision strobe lights. See § 91.209(b). However, §&#xA;  91.209(b), does give the PIC the discretion to turn off the anticollision beacon and/or the anticollision strobe light system if&#xA;  the PIC determines that it is in the interests of safety to turn off&#xA;  either one or both of these components of the same lighting system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, the regulations say you should turn them both on, but as PIC it's up to you to determine if using them is safe or not, and if not then you are allowed to turn (or leave) them off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practically speaking, I've always been taught to turn the beacon on before starting the engine because it's there to tell people near the aircraft that the engine is running or about to be running. The strobes should go on any time you need to be highly visible (which is most of the time), but not if using them would blind someone else or even yourself, e.g. taxiing or flying in clouds. The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM_Basic_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM 4-3-23&lt;/a&gt; has more details on that, in addition to the parts that you quoted.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-04-30T13:15:15.823" LastActivityDate="2015-04-30T13:15:15.823" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14449" PostTypeId="2" ParentId="14435" CreationDate="2015-04-29T14:53:21.790" Score="0" Body="&lt;p&gt;I learned that applying carb-heat when throttling down has nothing to do with Carb-Icing, but instead is to prevent shock-cooling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the engine is running at full power, it is creating a lot of heat.&#xA;When you throttle down rapidly, suddenly much less heat is being generated, but the engine is still being rapidly cooled.  This rapid cooling can create stress as the metal parts of the engine contract at different rates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applying Carb-heat directs available heat into the carburetor, and by association, the overall engine, which slows down the cooling of the engine and reduce the stress from rapid cooling.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-04-29T14:53:21.790" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14450" PostTypeId="2" ParentId="14435" CreationDate="2015-04-29T14:57:44.460" Score="0" Body="&lt;p&gt;The final authority on the use of carb heat is the POH, unless the POH itself leaves it to the pilot to make a judgement call, in which case you have to reference your knowledge of carb icing formation, the specifics of the aircraft's system, your intended operating parameters, and current atmospheric conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your instructor asking you to use carb heat when reducing power is likely both in line with the POH (can't remember for certain, it's been years since I've seen a -152 POH) as well as general prudence when operating carbureted aircraft, especially something with an engine that small.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-04-29T14:57:44.460" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14451" PostTypeId="2" ParentId="14435" CreationDate="2015-04-29T15:26:16.387" Score="8" Body="&lt;p&gt;At full throttle, manifold pressure is high, close to ambient pressure at that altitude.  At partial throttle or at idle, manifold pressure is low.  It is the transition from higher pressure (ambient) to low pressure (in the induction manifold) that causes cooling.  Think of why ambient temperature is cooler at 10,000 feet MSL than it is at 1,000 MSL.  So moving the throttle to a lower power position will cool the carburetor.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advice is right, follow the instructions in the POH.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-04-29T18:11:09.740" LastActivityDate="2015-04-29T18:11:09.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14453" PostTypeId="2" ParentId="14437" CreationDate="2015-04-29T16:10:05.270" Score="14" Body="&lt;p&gt;Everything that you say in your question is correct, and to address your reliability concerns, as part of certification the FAA requires certain hardware testing (EMI testing, decompression testing, etc.) of any EFB, including the iPad.  They are not however, certified to the same standards as avionics, because a failure of an iPad does not create the same safety issue as other certified parts.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond the testing for certification, there is required testing by the certificate holder before any update may be applied at the end user level, and part of the approval process requires written contingency procedures that are approved by the FAA for use in the event of a failure of the iPad(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, at least two are required in the cockpit for dispatch unless the paper equivalents of all electronic documents that they are approved for are available (charts, operations manuals, AFM's, flight logs, etc.).  If they failed prior to takeoff, this is likely why they returned to the gate.  There are contingency procedures for an in-flight failure of a single iPad, and for failure of all iPads on board.  These are written by each applicant but typically require &quot;anticipated information&quot; to be manually recorded from the working iPad, or using another source (FMS, ATC, data link, internet, satellite phone, etc.) to get the information if they both fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a ton of guidance/requirements available for those wanting to use COTS hardware for EFB's.  Also keep in mind, that using an iPad as an EFB is only a few years old, but EFB's have been used much longer than that.  Typically in the past, a Windows based tablet computer was used (talk about reliability issues), and the procedures so far have worked quite well.  I don't know of a single accident caused by an EFB failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether or not the iPad is on the MEL depends on the class of EFB that it is certified as.  If it is certified as &quot;carry on&quot; equipment, then it is not required (other than by company policy) so will not be on the MEL.  If it is &quot;installed/mounted&quot; in the aircraft, then it may be listed in the MEL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For lots more information, see:&lt;br&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_120-76c.pdf&quot;&gt;AC 120-76C - Guidelines for the Certification, Airworthiness, and Operational Use of Electronic Flight Bags&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-04-29T16:42:10.587" LastActivityDate="2015-04-29T16:42:10.587" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14454" PostTypeId="1" CreationDate="2015-04-29T19:12:08.613" Score="19" ViewCount="22831" Body="&lt;p&gt;Why are aircraft turbine blades made of nickel alloys? What is the advantage of using them? Why did they replace steel alloys for turbine blades?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to overcome failure cases of turbine blades?&lt;/p&gt;&#xA;" OwnerUserId="8325" LastEditorUserId="6979" LastEditDate="2015-04-30T15:40:32.637" LastActivityDate="2015-04-30T15:40:32.637" Title="Why are aircraft turbine blades made of nickel alloys?" Tags="&lt;aircraft-design&gt;&lt;turbine&gt;&lt;blade&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14455" PostTypeId="2" ParentId="14454" CreationDate="2015-04-29T19:29:27.387" Score="14" Body="&lt;p&gt;Their main advantage is higher strength at elevated temperatures. With elevated I mean temperatures up to 1200°C, which is what you will find in modern, &lt;a href=&quot;http://www.thermopedia.com/content/759/&quot; rel=&quot;nofollow noreferrer&quot;&gt;film-cooled&lt;/a&gt; high-performance turbines where the gas temperature is even a few hundred centigrades higher than that. Steel would melt and other materials like &lt;a href=&quot;https://aviation.stackexchange.com/questions/11481/why-are-turbine-blades-not-made-out-of-titanium-only-compressor-blades&quot;&gt;titanium&lt;/a&gt; would quickly oxidize, and only nickel alloys or ceramics are up to the job. Being still too brittle for everyday use, ceramics have not managed to escape the laboratory, so nickel alloys is all we have for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Failures are overcome by shutting the engine down and scheduling it for repair. When a turbine blade fails, the engine will develop an imbalance that might cause secondary damage due to vibrations. A single blade loss can be tolerated for a while, especially when power setting is reduced, but should be repaired as soon as possible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-04-29T19:35:50.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14456" PostTypeId="2" ParentId="14454" CreationDate="2015-04-29T19:42:47.653" Score="25" Body="&lt;p&gt;Not all turbine blades are made of nickel alloy, some blades are made of such family of alloys but clearly not all. Some blades are actually made of &lt;a href=&quot;http://www.rolls-royce.com/about/our-technology/gas-turbine-technology/turbines.aspx&quot;&gt;ceramic materials&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbine is always located after combustion chamber and the temperature which the first stage of turbine blades is able to resist is a proof of high technology engine. Those blades are exposed over to 2000ºC; the melting point of steel is around 1100ºC, and nickel can go much further up to &lt;a href=&quot;http://en.wikipedia.org/wiki/Nickel&quot;&gt;1700ºC&lt;/a&gt;. Ceramic can go even further. Note that there is also a significant difference between external flow temperature and surface temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a high melting point material is one way to solve the problem, there are also ways to reduce the effective temperature over the surface of the metal like using &lt;a href=&quot;http://www.me.umn.edu/labs/tcht/measurements/what.html&quot;&gt;film cooling&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/i26Ig.jpg&quot; alt=&quot;Turbine blade showing cooling holes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the figure I introduced above you can see holes in the blade, where &quot;cooling air&quot; (maybe at 400ºC) flows out of the blade creating effectively a film that goes around the blade protecting (cooling) it from external temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However a metal exposed at a high temperature (below the melting point) is not behaving in the same way as at normal temperature. There are some phenomena affecting the materials like &lt;a href=&quot;http://en.wikipedia.org/wiki/Creep_(deformation)&quot;&gt;creep&lt;/a&gt;. When a material is exposed during long term to high temperatures close to the melting point and high stress at the same time (this is important) it starts suffering deformations that lead to a failure of the metal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So nickel alloys, apart for having a higher melting point are also having one of the best behaviours in creep environments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last stages of the turbine rotors, and more easily stators (less demanded in stress) are less exposed to creep conditions and are not needed to be manufactured in a nickel base alloy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to add as well, in order to reduce creep another approach followed (combined with previous) is to solidify the metal ensuring having a &lt;a href=&quot;http://en.wikipedia.org/wiki/Single_crystal&quot;&gt;single crystal&lt;/a&gt; metal (instead of being a polycrystalline metal). This is utmost art of material engineering (from my point of view).&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="1696" LastEditDate="2015-04-30T15:16:35.170" LastActivityDate="2015-04-30T15:16:35.170" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14457" PostTypeId="2" ParentId="14409" CreationDate="2015-04-29T21:59:35.063" Score="2" Body="&lt;p&gt;It's really dependant on 1) size and 2) type. I.E. if it's a DJI Phanatom, then it will just get shredded as its made out of plastic, possibly doing damage to the engine. On the other hand, if its a large multi rotor that's made of metal/carbon fiber, then the engine will most likely be damaged pretty badly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, TL,DR: if it's a consumer one, probably won't be much evidence, about as much as a bird, but with less blood. Of its large, then imagine a crane made of carbon fiber.&lt;/p&gt;&#xA;" OwnerUserId="8329" LastActivityDate="2015-04-29T21:59:35.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14458" PostTypeId="2" ParentId="14357" CreationDate="2015-04-29T22:10:23.717" Score="1" Body="&lt;p&gt;The question is not precise. If you make a 80Nm flight hop between two airports you will never reach cruise speed. Example ZRH-GVA with MD11 each Monday morning (aircraft positioning).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise speed may change during the flight due to unforeseen circumstances prior to take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise altitude changes during the flight when ship gets lighter. You start FL310, you may finish the flight at FL370. Or if the wind forecast was wrong, you may decide to fly lower at a different speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Computers are calculating during the climb the best speed, thrust setting to climb using temperature, wind forecast, fuel price, cost of operation. So your TOC could be anywhere. If you have engine anti ice on that is changing too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the question is not precise, the answer is not precise either: Make it average 2000 feet per minute and you will have your time to &quot;cruise alt&quot;.&lt;/p&gt;&#xA;" OwnerUserId="8331" LastEditorUserId="1696" LastEditDate="2015-04-29T22:21:09.993" LastActivityDate="2015-04-29T22:21:09.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14460" PostTypeId="2" ParentId="14108" CreationDate="2015-04-29T22:25:07.853" Score="1" Body="&lt;p&gt;An oxygen bottle is extremely heavy. And when you are on fire you don't want to have oxygen around. And in general when you have to use oxygen in an aircraft, something went wrong. A big jet is about 40 meters long which means you have at least 40 meters of oxygen pipe. By requirement oxygen should be provided from maximum altitude to around FL100 which means 20 or 30 minutes. 435 passengers needing 30 minutes of oxygen means 1 ton of deadload. Replenishing an oxygen bottle is a &lt;em&gt;pain&lt;/em&gt; for maintenance (tank temperature, pressure, ...). Maintenance and weight are key factors in the decision. &lt;/p&gt;&#xA;" OwnerUserId="8331" LastEditorUserId="753" LastEditDate="2015-04-30T08:31:05.597" LastActivityDate="2015-04-30T08:31:05.597" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14462" PostTypeId="1" CreationDate="2015-04-30T01:04:25.430" Score="14" ViewCount="11383" Body="&lt;p&gt;Reading &lt;a href=&quot;http://www.theguardian.com/business/2015/apr/29/demise-of-boeing-747-sign-of-changing-flight-patterns&quot;&gt;this article&lt;/a&gt;, I came across the quote :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots also enjoy its creature comforts: at BA the 747s are known as&#xA;  the ensuite fleet. “Our little bedroom is within the cockpit: you can&#xA;  stick your pyjamas on and clean your teeth without anyone seeing you.&#xA;  And coming out the bunk when you wake up, it’s a different light and&#xA;  you’re in a plane cockpit in the sky,” he says.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know there are crew sleep areas on large aircraft but I've never heard of there being a bunk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have a floor plan for the cockpit which would illustrate how do they fit those cabins there?&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="167" LastEditDate="2015-04-30T16:46:02.863" LastActivityDate="2016-12-05T07:09:50.540" Title="Is there an aircrew bunk in the 747 cockpit?" Tags="&lt;boeing-747&gt;&lt;crew&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14463" PostTypeId="2" ParentId="13830" CreationDate="2015-04-30T02:33:40.793" Score="3" Body="&lt;p&gt;Yes.  It appears to be the case for &amp;quot;steam gauges&amp;quot;.  At least for a traditional vertical speed indicator.  It's a great question and not one I had considered before.  At first glance, I suspected you may be right, though I don't ever remember actually learning that.&lt;/p&gt;&#xA;&lt;p&gt;To prove the theory, one pilot &lt;a href=&quot;http://www.x-plane.com/x-world/austins_adventures/2012-2/may-2012-your-altitude-is-wrong/&quot; rel=&quot;nofollow noreferrer&quot;&gt;apparently took his airplane&lt;/a&gt; with a traditional steam gauge altimeter/VSI up to FL220 and found the following:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;=&amp;gt;Your altimeter is perfectly accurate at the airport if you enter your barometric pressure correctly.&lt;/p&gt;&#xA;&lt;p&gt;=&amp;gt;At the cruise altitude of about 8,500 feet or so, your altimeter is off by about FIVE-HUNDRED FEET.&lt;/p&gt;&#xA;&lt;p&gt;=&amp;gt;At that altitude, it does not matter much that your altimeter is off, because everyone else’s is off by the same amount, and you are far from the airport, and thus landing.&lt;/p&gt;&#xA;&lt;p&gt;=&amp;gt;The error always seems to be off in the safe direction: You are always HIGHER than you think. Clearly, when they designed the system in 50’s, they designed the altimeters to follow the most conservative lapse-rate we could encounter, so in real-world flying, we are almost-always much HIGHER than we thought, which must be the safest error we can make.&lt;/p&gt;&#xA;&lt;p&gt;=&amp;gt;&lt;strong&gt;The vertical speed indicator perfectly tracks the PRESSURE-based altimeter, not the true altitude, so the vertical speed indicator can be perfectly used to see how much the altimeter will change over time, the ACTUAL climb or descent rate of the plane is actually considerably DIFFERENT… at high altitudes, by 1,290 parts in 24,000, or just OVER FIVE PERCENT.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8333" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-04-30T10:43:33.660" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14464" PostTypeId="2" ParentId="12431" CreationDate="2015-04-30T02:55:38.840" Score="7" Body="&lt;p&gt;The system projects the altitude that an aircraft will be at based on recent track and a calibrated &quot;look ahead time&quot; and an expected controller response time.  That value is then compared to a calibrated altitude floor.  If the aircraft is projected to be below the floor, then the controller will be alerted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific values for all those things are calculated to minimize false alarms, accommodate the type of operation and local operational needs.  The values are specific to that facility and that area and so a straight answer isn't exactly possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a few interesting resources in case they help.&#xA;&lt;br&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Minimum_Safe_Altitude_Warning_(MSAW)&quot; rel=&quot;noreferrer&quot;&gt;Minimum Safe Altitude Warning&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/publication/files/20090519-msaw-guid-v1.0.pdf&quot; rel=&quot;noreferrer&quot;&gt;EUROCONTROL MSAW Guide&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8333" LastEditorUserId="572" LastEditDate="2015-04-30T11:26:05.083" LastActivityDate="2015-04-30T11:26:05.083" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14465" PostTypeId="2" ParentId="14462" CreationDate="2015-04-30T05:37:07.960" Score="6" Body="&lt;p&gt;I found it difficult to find a specific floor plan.  I've seen references that the 747 had a lot of different plans, with many airlines having a crew rest area in the rear of the upper deck rather than off the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No floor plan, but there are several location with photos available of the  rest area on the -8.  &lt;a href=&quot;http://www.cnet.com/pictures/look-inside-boeings-747-8-intercontinental-photos/6/&quot; rel=&quot;noreferrer&quot;&gt;CNET&lt;/a&gt; has one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No longer on the Boeing web site, there is an &lt;a href=&quot;https://web.archive.org/web/20140701050144/http://www.boeing.com/assets/pdf/commercial/startup/pdf/freighters/747f_int.pdf&quot; rel=&quot;noreferrer&quot;&gt;archived copy&lt;/a&gt; of the crew rest area for a -400 freighter that has a floorplan for the area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.businesstraveller.asia/news/exclusive-klms-new-business-class-layout-revealed&quot; rel=&quot;noreferrer&quot;&gt;This&lt;/a&gt; page isn't as detailed, but shows the crew rest area on a 747 to scale with more of the upper deck.  Unfortunately it lacks detail with how it connects to the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And not a 747, but &lt;a href=&quot;http://helpingfearofflying.yuku.com/topic/360/Boeing-787-DreamLiner&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; is a page with a graphic of the 787 crew rest area.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-04-30T05:37:07.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14467" PostTypeId="2" ParentId="14286" CreationDate="2015-04-30T11:05:43.883" Score="2" Body="&lt;p&gt;I would say that joining the Air Force is &lt;strong&gt;not&lt;/strong&gt; a good way to become an airline pilot. Becoming an Air Force pilot is an excellent way to become an airline pilot. However, becoming an Air Force pilot is incredibly competitive. If you are not an Air Force Academy grad, it's even more. They have about &lt;a href=&quot;http://usmilitary.about.com/od/airforcejoin/ss/afpilot_8.htm&quot; rel=&quot;nofollow&quot;&gt;1,400 training slots available&lt;/a&gt; and if you don't get one of them, you still have to serve. It's an excellent job and you will learn a lot, but it will put you a few years back in airline seniority.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there is now a push to get flight training largely excluded from the GI Bill (&lt;a href=&quot;https://www.congress.gov/bill/114th-congress/house-bill/476&quot; rel=&quot;nofollow&quot;&gt;HR 476&lt;/a&gt;). If that happens, you lose even that benefit which is great for reducing a large expense towards that airline job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do get that Air Force flying job, then it should not put you behind other pilots. A lot of pilots do it that way and they are well respected.  However, the government is starting to make it more difficult (and expensive) to make the transition. If you end up in a single engine fighter like the F16, it's even more so because you need to get some multi-enging time, typically at your own expense. There are some other requirements as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a great career and a great path into the airlines but not a sure thing at all.  &lt;/p&gt;&#xA;" OwnerUserId="8333" LastEditorUserId="8333" LastEditDate="2015-04-30T11:53:26.987" LastActivityDate="2015-04-30T11:53:26.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14468" PostTypeId="2" ParentId="14437" CreationDate="2015-04-30T12:44:12.530" Score="4" Body="&lt;p&gt;Many of the answers here are excellent in general.  Maybe I can help flesh out some of the details.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that American had issues with the application from Jeppesen through which they distribute the charts used to navigate.  In this case I believe it was the airport diagram for DCA which conflicted with an earlier version on the iPad.  This caused the iPad to unexpectedly crash and the app had to be deleted and reinstalled to fix the issue (a common fix on the iPad).  This is a bunch of data to download all at once, especially by multiple pilots over a wi-fi connection.  I suspect that increased the delay.  (&lt;a href=&quot;http://qz.com/393909/american-airlines-planes-are-grounded-because-their-pilots-ipads-have-crashed/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt; plus personal accounts)  This is the electronic equivalent of every affected pilot spilling coffee on their entire set of charts and manuals at the same time.  As others have said, if you don't have manuals and charts, you legally can not leave. That's the core reason why these planes had to return to the gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We use the same app (didn't have this issue that I know of) and the same hardware.  It has a lot of benefits for the pilots and the airlines.  However, in addition to the concerns that Lnazfiger raises, there are a bunch of others especially when the COTS product is the iPad which was never designed for enterprise use.  This creates a bunch of issues&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Apps and data can be pushed out onto the device without solid&#xA;testing &lt;/li&gt;&#xA;&lt;li&gt;iPad has no backward compatibility with OS changes and&#xA;the user can control OS updates. This often breaks the apps being&#xA;used if they aren't yet updated to the new OS.  The company can't&#xA;prevent this &lt;/li&gt;&#xA;&lt;li&gt;The user has immense control over the ecosystem,&#xA;opening it up to risks, threats and user introduced instability &lt;/li&gt;&#xA;&lt;li&gt;These systems weren't designed for this kind of data or these&#xA;applications and, until recently, Apple approached the&#xA;implementation of these devices on an enterprise basis as if they&#xA;are simultaneously selling thousands of consumer iPads.  My&#xA;understanding is that as sales drop off, they are starting to look&#xA;more at enterprise deployments but they wanted little to do with the&#xA;carriers originally. &lt;/li&gt;&#xA;&lt;li&gt;The application ecosystem must be tested by&#xA;the carrier to ensure that there aren't conflicts between apps and&#xA;data.  Apple does a nice job of separating apps but that doesn't&#xA;mean issues don't or can't occur. &lt;/li&gt;&#xA;&lt;li&gt;Some of the companies producing&#xA;these apps are not originally software firms (e.g. Jeppesen, WSI,&#xA;Boeing.)  Some do a great job but I know that my experiences with&#xA;the same Jeppesen app aren't stellar.  Nothing this way, but I've&#xA;had issues I consider sloppy.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Of course, these same risks present opportunities for enterprising software engineers and it's improving as the market improves but all of the risks and these are still present.  At the same time, the benefits still outweigh the risks.  I suspect that companies like Boeing and Jeppesen having their name in the press attached to issues like this will be pressed to fix any issues quickly.&lt;/p&gt;&#xA;" OwnerUserId="8333" LastEditorUserId="8333" LastEditDate="2015-04-30T15:28:21.437" LastActivityDate="2015-04-30T15:28:21.437" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14469" PostTypeId="2" ParentId="14286" CreationDate="2015-04-30T13:05:04.713" Score="7" Body="&lt;p&gt;As previously mentioned, joining the Air Force is a great way to become an airline pilot.  Now that we've established that... Do NOT join the Air Force to become an airline pilot or to fly.  Join because you want to serve your country and if you are lucky enough then you will get to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's break down the timeline and steps to get there:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commissioning Sources:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;USAFA:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;4 years, paid for, excellent opportunities, sets you up great for your career&lt;/li&gt;&#xA;  &lt;li&gt;horrible REAL college experience, don't get to experience much of the real world&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;AFROTC:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;4 years, MAY get a scholarship to have SOME paid for, real college experience&lt;/li&gt;&#xA;  &lt;li&gt;Pretty good networking but not as good as USAFA&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;OTS:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;9.5 weeks&lt;/li&gt;&#xA;  &lt;li&gt;Little to zero networking, may/may not prepare you to be an officer&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Your best chances of getting a pilot slot are through the Academy.  Through AFROTC you apply to a Rated board; however, you may get selected as a CSO, RPA, etc.  With OTS you apply for specific positions (ie. pilot only) so you won't do something you don't necessarily want to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen all 3 sources and ultimately finished with OTS.  I think AFROTC is probably the best option if lots of pilot slots are being given out.  Having said that, USAFA is really the only guaranteed way if you want to deal with a lot BS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now you've received your pilot slot and commissioned as an officer, now what?  On to UPT....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll go to either Laughlin, Vance, Columbus, or if you get selected for ENJJPT then to Sheppard.  Here you will go through Initial Flight Screening (I think it's been changed to IFT now) where you'll fly the DA-20 for approximately 20 hours up in Colorado.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, everything you've worked for... You start slackademics... 6 weeks of Aerospace Physiology, T-6 Systems, Instruments, Formation, etc.  You'll then move on to the flight line where you'll fly the T-6 and work 12 hours a day and then come home and study for a few more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After about 6 months you'll track to either T-38s, T-1s, or Helos.  Statistically a class size is about 24 studs with 4-5 T-38s (maybe a Guard or couple internationals in here too), 1 Helo, and the rest to T-1s.  You'll move into Phase 3 and repeat the Academics and flying for your jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You reach drop night after 52+ weeks of UPT.  You're racked and stacked amongst your peers and given a jet you may or may not want.  Lately fighters have been dropping quite a bit, but it comes and goes.  Most likely your class of 24 studs will get 2-3 fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you got a heavy (which will be most of your class) they'll nugget off to their next base to do about 6-9 months of upgrade training in the C-130, KC-135, KC-10, U-28, etc.  Other than that, I can't tell what exactly that involves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But let's say you were one of the lucky ones and dropped a fighter... Next you'll move on to Intro to Fighter Fundamentals (IFF) where you'll continue to fly the -38.  Here you'll learn to fly very, very basic BFM and BSA.  They're teaching you to be the best wingman you can be.  If you graduate you'll move onto your B-course...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-course locations and times depend on what jet you get.  For the Viper, it's about 9 months.  This is where you'll go through your IQT (initial qualification) and learn how to employ.  Once you graduate you'll nugget of to your first fighter squadron where you'll complete MQT (mission qual).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After 250-350 hours, if you're good then you'll be sent to 2-ship upgrade training.. And this basically continues your entire career.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to serve and fly doing it, then great!  But I would not look at military flying as an entrance into the airline world.  Yes, you will be able to fly circles around your peers after your military training, but it will probably be the hardest you've ever worked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I've laid out, this process has taken most of us years and guess what, the training never stops.  I haven't even really talked about all the TDYs, deployments, missed holidays, missed birthdays, missed anniversaries, etc.  You will be away from your family a lot.  And when you are home you're going to be working 60+ hours a week.  And when you're home for the night you're going to need to study.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't want to discourage you, but just want you to see what Air Force flying is really like.  Good luck!&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorUserId="72" LastEditDate="2015-05-01T00:48:22.503" LastActivityDate="2015-05-01T00:48:22.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14470" PostTypeId="1" AcceptedAnswerId="14471" CreationDate="2015-04-30T14:42:30.763" Score="20" ViewCount="4369" Body="&lt;p&gt;Do you know any airline company owner who holds ATPL licence and flies one of the company's aircraft occasionally in normal operations just because (s)he likes to do it?&lt;/p&gt;&#xA;" OwnerUserId="8337" LastEditorUserId="1467" LastEditDate="2015-04-30T15:29:54.933" LastActivityDate="2019-07-17T06:26:30.720" Title="Is there any airline company owner who also works as a pilot?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;" AnswerCount="7" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14471" PostTypeId="2" ParentId="14470" CreationDate="2015-04-30T14:47:39.813" Score="33" Body="&lt;p&gt;Yes, &lt;a href=&quot;https://en.wikipedia.org/wiki/Niki_Lauda#Roles_beyond_F1&quot;&gt;Niki Lauda&lt;/a&gt;, former Formula 1 pilot and ATPL holder, founded &lt;a href=&quot;https://en.wikipedia.org/wiki/Lauda_Air&quot;&gt;Lauda Air&lt;/a&gt;, for which he also &lt;a href=&quot;http://www.motorsport-magazin.com/formel1/news-24285-historisches-niki-lauda-geschichte-eines-oesterreichers.html&quot;&gt;worked as PIC&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Lauda returned to running his airline, Lauda Air, on his second Formula One retirement in 1985. During his time as airline manager, he was appointed consultant at Ferrari as part of an effort by Montezemolo to rejuvenate the team. After selling his Lauda Air shares to majority partner Austrian Airlines in 1999, he managed the Jaguar Formula One racing team from 2001 to 2002. In late 2003, he started a new airline, Niki. Lauda holds a commercial pilot's licence and from time to time acted as a captain on the flights of his airline. Lauda Air ceased operations in July 2013.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-04-30T14:52:57.857" LastActivityDate="2015-04-30T14:52:57.857" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14472" PostTypeId="5" CreationDate="2015-04-30T15:44:33.130" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-04-30T15:44:33.130" LastActivityDate="2015-04-30T15:44:33.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14473" PostTypeId="4" CreationDate="2015-04-30T15:44:33.130" Score="0" Body="A blade is a thin section of material designed to push or be pushed by a flow. This can be a turbine blade which makes up the compressor or turbine section of a gas turbine, or the blades of a propeller or rotor." OwnerUserId="6979" LastEditorUserId="1696" LastEditDate="2015-04-30T16:13:34.267" LastActivityDate="2015-04-30T16:13:34.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14474" PostTypeId="2" ParentId="14470" CreationDate="2015-04-30T15:56:34.870" Score="13" Body="&lt;p&gt;Although not an airline Howard Hughes was a test pilot for some of the Hughes Aircraft planes including the famous &lt;a href=&quot;http://en.wikipedia.org/wiki/Hughes_XF-11&quot; rel=&quot;nofollow&quot;&gt;XF-11&lt;/a&gt; that he crashed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find any information on if he ever flew any of the Hughes/Air West planes in a commercial situation or if he had a CPL but its worth mentioning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some searching I did find &lt;a href=&quot;http://www.famoustexans.com/howardhughes.htm&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; which states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The only real job Hughes ever had also came in 1933. He signed on as a co-pilot for American Airways. He applied under the name Charles W. Howard. The ruse was quickly discovered, however, and Hughes resigned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it seems he did at least try to be a commercial pilot at some point although this was long before the Hughes/Air West Days. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit 2:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I forgot about it, but &lt;a href=&quot;http://en.wikipedia.org/wiki/Buffalo_Airways&quot; rel=&quot;nofollow&quot;&gt;Joe McBryan&lt;/a&gt; the owner of Buffalo air a small freight and passenger airline in Canada and the focus of the History Channels show &quot;Ice Pilots NWT&quot; fly's some of the flights for the airline. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also seems that &lt;a href=&quot;http://en.wikipedia.org/wiki/Willie_Walsh_%28Irish_businessman%29&quot; rel=&quot;nofollow&quot;&gt;Willie Walsh&lt;/a&gt; the CEO of Aer Lingus and then British Airways was a 737 captain however it does not seem that he held these positions while being a captain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Collett_E._Woolman&quot; rel=&quot;nofollow&quot;&gt;Collett Everman Woolman&lt;/a&gt; one of the founders of Delta Airlines (and eventually the CEO) did fly for them when them when they were a crop dusting business (and legally an airline) but I cant find any info on if he flew passenger or mail flights for them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Walter_Varney&quot; rel=&quot;nofollow&quot;&gt;Walter Varney&lt;/a&gt; the founder of both Continental and United Airlines was an airmail pilot for United at one point (possibly also during passenger operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Leon_D._Cuddeback&quot; rel=&quot;nofollow&quot;&gt;Leon D Cuddeback&lt;/a&gt; another founder of United Airlines is credited as flying the first airline flight in the country so I'd say he makes the list. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/A._Felix_du_Pont,_Jr.&quot; rel=&quot;nofollow&quot;&gt;A Felix duPont&lt;/a&gt; one of the founders of Allegheny Airlines (eventually US Airways) was a test pilot for Focker and an aviation enthusiast as well as serving during WWII for the Air Transport Command although it does not seem that he flew commercially. His brother &lt;a href=&quot;http://en.wikipedia.org/wiki/Richard_Chichester_du_Pont&quot; rel=&quot;nofollow&quot;&gt;Richard Chichester duPont&lt;/a&gt; was also an aviation enthusiast and founder of Allegheny Airlines although its unclear if he ever flew for them he does hold some aviation awards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find a list of US based airlines &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airlines_of_the_United_States&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and the rest of the world &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airlines&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; if you want to continue cross referencing owners who were also possibly pilots. It seems that a lot of the early founders/pioneers in aviation were also founders of airlines.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-02T01:48:19.610" LastActivityDate="2015-05-02T01:48:19.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14475" PostTypeId="1" AcceptedAnswerId="14476" CreationDate="2015-04-30T15:57:53.923" Score="11" ViewCount="3308" Body="&lt;p&gt;In an airliner, such as an A380, what indications do the pilots have that an engine has thrown a fan blade?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will that always result in destruction (of the engine)?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-05-01T23:24:00.073" Title="What are the indications that your turbofan engine has &quot;thrown a blade?&quot;" Tags="&lt;jet-engine&gt;&lt;turbine&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14476" PostTypeId="2" ParentId="14475" CreationDate="2015-04-30T16:10:13.363" Score="13" Body="&lt;p&gt;Turbofan engines are designed and &lt;a href=&quot;https://youtu.be/wcALjMJbAvU&quot;&gt;tested to contain a fan blade failure&lt;/a&gt;. However, this is a violent event and will cause serious damage to the engine. The engine and surrounding components are subjected to large forces and vibrations, and the engine can ingest debris from the damage to the fan, causing further damage. There will likely be an investigation, and the engine will probably be scrapped due to the widespread damage to different components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the pilots, it will seem like a bird strike, but probably worse. There will be a loud noise as the fan blade separates and collides with the fan case and following blades. The fan will then be out of balance, so heavy vibrations will follow as the shaft loses its rotational energy. The pilots will be able to tell which engine has failed by the loss of thrust, as well as the indications of vibration and failure on the instruments for that engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the fan does not get stuck, it will continue to windmill, which will result in ongoing vibration from that engine.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-04-30T16:10:13.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14478" PostTypeId="1" AcceptedAnswerId="14479" CreationDate="2015-04-30T16:47:42.790" Score="6" ViewCount="573" Body="&lt;p&gt;Let's say we're flying the JORJO2 SID (&lt;a href=&quot;http://155.178.201.160/d-tpp/1505/05028JORJO.PDF&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt;,&lt;a href=&quot;http://155.178.201.160/d-tpp/1505/05028JORJO_C.PDF&quot; rel=&quot;noreferrer&quot;&gt;2&lt;/a&gt;) out of KPWK (RBS transition). We are told &quot;climb via the SID&quot;. Page 2 of the SID says &quot;maintain 3000&quot; but the MEA on page 1 is 4000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there ever a time we are supposed to climb to the MEA?  Or are we to maintain the top altitude in the SID (3000) until specifically cleared higher?  I'm just not sure what the purpose of displaying the MEA is on this chart, lost comms maybe?&lt;/p&gt;&#xA;" OwnerUserId="8338" LastEditorUserId="62" LastEditDate="2015-04-30T17:02:59.990" LastActivityDate="2015-04-30T17:02:59.990" Title="Why do SIDs include an MEA?" Tags="&lt;instrument-flight-rules&gt;&lt;sid-star&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14479" PostTypeId="2" ParentId="14478" CreationDate="2015-04-30T16:56:39.663" Score="6" Body="&lt;p&gt;Yes it's for lost comm.  If you look at the MOCA you still have the required obstacle clearance.  MOCA only gives you reception within 22 NM of the NAVAID, while MEA gives reception along the route.  If this was not an RNAV procedure I'd expect your level off altitude would probably be the MEA (just my assumption!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case you would maintain 3,000' until cleared higher.  If you were to lose comm you'd fly the higher of filed, assigned, MEA, or expected altitudes.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-04-30T16:56:39.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14480" PostTypeId="1" AcceptedAnswerId="14482" CreationDate="2015-04-30T18:08:05.893" Score="11" ViewCount="4059" Body="&lt;p&gt;Theoretically, I know it is possible. I know the benefits of &lt;a href=&quot;http://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;noreferrer&quot;&gt;fly-by-wire&lt;/a&gt; too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question(s) most revolve around:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;why it hasn't been done?&lt;/li&gt;&#xA;&lt;li&gt;What challenges&lt;sup&gt;1&lt;/sup&gt; would there be?&lt;/li&gt;&#xA;&lt;li&gt;What benefits are there by not implementing it even for new light GA aircraft&lt;sup&gt;2&lt;/sup&gt; being produced?&lt;/li&gt;&#xA;&lt;li&gt;I know that many smaller airplanes (e.g. Cessna 172) do have fly-by-wire flaps. Why the remaining &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot; rel=&quot;noreferrer&quot;&gt;flight controls&lt;/a&gt; don't use this technology?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;em&gt;Not considering money as an issue.&lt;/em&gt;&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;: &lt;em&gt;I couldn't find any reference of it for &lt;a href=&quot;http://cessna.txtav.com/en/single-engine/skyhawk&quot; rel=&quot;noreferrer&quot;&gt;Cessna Skyhawk&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="755" LastEditDate="2015-05-01T01:28:50.150" LastActivityDate="2020-08-26T04:51:38.510" Title="Can light GA aircraft implement fly-by-wire technology?" Tags="&lt;aircraft-design&gt;&lt;general-aviation&gt;&lt;fly-by-wire&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14481" PostTypeId="2" ParentId="14480" CreationDate="2015-04-30T18:28:30.527" Score="3" Body="&lt;p&gt;Fly by wire costs weight in actuators for the control surfaces and power to move those actuators. It's simpler if there are hydraulics already needed but many small GA use pulleys and control-rods to link the control surfaces to the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you need a few computers (redundancy) and sensors feeding into them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the plane should still be safe to fly and be able to make a controlled landing after the fly-by-wire system fails entirely.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-04-30T18:28:30.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14482" PostTypeId="2" ParentId="14480" CreationDate="2015-04-30T18:52:54.653" Score="14" Body="&lt;p&gt;There are multiple factors here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first and main one is of course weight. Fly-By-Wire requires computers and hydraulics to actuate the surfaces in a small plane weight is critical and a FBW system may be the difference between 3 and 4 passengers in total capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next that comes to mind is certification, I'm not sure exactly how this works but I would think that FBW implementation in a current airframe would require a recertification of sorts. With that being said many GA planes flying out there like the 182, Piper Arrow and other similar things still made today are sporting designs first flown more than 30 years ago. It's a simple matter of, &quot;if it ain't broke don't fix it&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think that basic service and maintenance would also become more complex and worst of all more costly. I don't know much about the cost of these systems so I wont comment father than speculation like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a safety concern in small planes (and I'm sure even bigger planes) if control feedback is not present. &lt;a href=&quot;http://www.aviationlawmonitor.com/2010/12/articles/cirrus-aircraft/steve-wilson-the-cirrus-airplane-has-serious-problems/&quot;&gt;This Article&lt;/a&gt; outlines some serious concerns with the Cirrus side stick and its lack of feedback (not fly by wire but some of the ideas carry over to the FBW systems that don't have feedback).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A Note on the 172:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I understand FBW leads me to think the 172 does NOT have FBW flaps. While they are electronically actuated I consider FBW (and by definition):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...flight control computers determine how to move the actuators at each control surface to provide the ordered response&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no computation done in a 172's flaps to my knowledge, if you move the switch they will move. While the flaps are not directly cable driven I would consider the lack of computer to keep the 172 out of the FBW category but thats just personal opinion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also of note, the 172 did not always have electronic flaps - that was a later addition to the aircraft in '65.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A Note On Cost:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although you note that one must ignore cost in this case you really can't. A FBW system would make a GA plane even more expensive than they are. This is a very real and very limiting factor in aviation. With an unlimited budget you could develop, certify, and regularly fly a FBW small plane that was chock full of gadgets but the FAA approval process is what it is and cost is a very real limit for aircraft makers.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="938" LastEditDate="2015-05-01T00:55:28.280" LastActivityDate="2015-05-01T00:55:28.280" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14483" PostTypeId="2" ParentId="14480" CreationDate="2015-04-30T19:07:10.960" Score="7" Body="&lt;p&gt;The biggest reason that fly-by-wire hasn't been implemented yet is the complexity of the change required. Larger aircraft already started using hydraulics to move their control surfaces, and a fly-by-wire system adds to this by actuating them with a computer. Smaller aircraft do not have the need for hydraulics, so they must move from direct linkages to computer control. &lt;a href=&quot;https://aviation.stackexchange.com/a/14481/1696&quot;&gt;As ratchet freak says&lt;/a&gt;, this adds a lot of weight and complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps are much more simple than a whole control system. They don't move very often, and if they fail, the plane is still able to take off and land safely. The pilot directly controls them on a simple scale of up to down. The rest of the flight controls must be able to move throughout the flight, be quick to respond, and implement computer control logic. Failure is much more critical than the flaps as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a large inertia of history to overcome. The industry is used to traditional control linkages. Moving away from this will incur a large cost in developing the system, testing it, and getting it approved by regulators. With sales at their current levels, adding this to older designs may not be worth the cost of development, and new designs would have to make the option attractive compared to other options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A big hurdle to overcome is also safety. While larger aircraft have managed to implement these systems, the challenges are greater with smaller aircraft. Mechanical controls are generally more simple to inspect and repair, and the GA maintenance community would have to learn many new skills to work with the new systems. Redundancy and safe back-up controls would have to be included in a smaller airframe. All of this when regular controls work perfectly fine and are efficient in cost, weight, and complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As reirab commented, stall training is required for a PPL. It makes sense that pilots should still know how to handle a stall, in case the protections fail. But this means the system must have an option to be inhibited. So although the plane should usually prevent stall, pilots will also need to know how to recognize and handle system failures, which even experienced pilots with an ATPL &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20081127-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;can struggle with&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what benefits are there? &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/November/Pilot/Fly-by-wire&quot; rel=&quot;nofollow noreferrer&quot;&gt;Safety is one area&lt;/a&gt; where fly-by-wire can offer great improvements. A fly-by-wire system can automatically prevent the pilot from stalling the plane or otherwise putting the plane in a position where it is out of control. These kinds of incidents are much more common in general aviation than with airliners, so there is a huge potential for reducing the number of accidents. The plane can also trim itself automatically and deal with many of the aerodynamic idiosyncrasies that different small planes have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationweek.com/awin/ga-airframe-manufacturers-embrace-fly-wire&quot; rel=&quot;nofollow noreferrer&quot;&gt;There is progress being made here though&lt;/a&gt;. Fly-by-wire technology has been used on business jets like the Dassault Falcon 7X. Diamond is working on a fly-by-wire option for the DA-42, as well as the future DA-62. As of 2012 they were hoping to have this available around now, but there are at least manufacturers working on bringing this technology to market.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-04-30T21:29:09.527" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14484" PostTypeId="2" ParentId="14475" CreationDate="2015-04-30T19:09:19.463" Score="13" Body="&lt;p&gt;engineer and pilot here - formerly of JPL. I've seen blade loss tests and any modern high performance engine will violently destroy itself if a blade is lost. You can see &lt;a href=&quot;https://www.youtube.com/watch?v=5-8_Gnbp2JA&quot;&gt;tests of this on youtube&lt;/a&gt; for example at that link or by searching on &quot;jet engine blade-out test&quot; (without the quotes). (User fooot gave a longer example video as well.) In these tests they typically use a (very small, prebalanced) explosive charge to separate one blade from the spindle and then the engine vibrates itself to pieces. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern engines are constructed near the very limits of the materials used. In fact there is a &lt;a href=&quot;http://www.c-fan.com/history.htm&quot;&gt;special joint venture company&lt;/a&gt; in the US that makes a lot of the fan blades and which exists just for this purpose. They use special tools to X-ray every blade and measure the center of gravity as the slightest bubble in composites or weight anomaly would be enough to destroy an engine. When a blade is lost, the off center mass causes an engine to vibrate itself violently to death.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In person you can't really hear anything but the vibration and destruction at these tests - I couldn't even hear the explosive charge when it went off (although it seems audible in some of those videos). As fooot noted above, the pilots are informed through the usual engine-out detection methods such as loss of telemetry (and it may start a fire which would be noted and dealt with by fire suppression systems on a larger jet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many companies including, I know, Rolls-Royce will invite the public to fan blade out tests to show how their engine bodies control the resulting carnage. It might be a fun afternoon if you're the type to visit aviation stackexchange :) They post videos online for the same reason and you can see a lot of very nice slow-motion videos on the subject.&lt;/p&gt;&#xA;" OwnerUserId="7688" LastActivityDate="2015-04-30T19:09:19.463" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14485" PostTypeId="2" ParentId="14462" CreationDate="2015-04-30T20:51:52.963" Score="13" Body="&lt;p&gt;Yes, there is a crew rest with two beds (bunk) connected to the cockpit on the 747. &lt;a href=&quot;https://aviation.stackexchange.com/a/14487/1696&quot;&gt;As MainMa notes&lt;/a&gt;, this can be found on 747-400 or 747-8 models, but not the older models. It can be seen on the seating charts here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tte4Q.jpg&quot; alt=&quot;Crew rest location on 747&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew rest is directly across from the two lavatories. While the lavatories open into the aisle of the cabin (grey area), the crew rest opens into the cockpit. There is a layout &lt;a href=&quot;http://s973.photobucket.com/user/randomperson8008/media/bcf.jpg.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; that shows a how the upper deck is arranged. It's a freighter, but is was converted from a passenger plane, so it has the same crew rest location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the introduction of the 747-400, the position for the flight engineer was removed (seen below), with those functions being replaced by computers. This opened up a bit of room behind the pilot seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/u6gej.jpg&quot; alt=&quot;747-100 Flight Engineer Station&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Flight_engineer%E2%80%99s_station_in_B747-100_cockpit.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-01T15:44:50.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14486" PostTypeId="2" ParentId="14475" CreationDate="2015-04-30T22:02:15.713" Score="4" Body="&lt;p&gt;If you lose a &quot;large&quot; blade like a fan blade, or a &quot;heavy&quot; blade like most turbine blades, the engine vibration monitors will instantly go off the scale and the engine control system should shut the engine down automatically. To give some idea of the forces involved, losing a fan blade from a large turbofan will create an force of about &lt;strong&gt;100 tons&lt;/strong&gt; on the engine, oscillating at a few thousand RPM until the rotor slows down. In a worst case scenario, the aftermath is enough to shake the entire aircraft to the level where walking about in the passenger cabin is difficult. But aircraft have survived that and landed safely, and for long distance flights over water the plane is certified to survive the consequences for up to 3 hours flight time before reaching the nearest land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if the tip of 10mm long high pressure compressor blade cracks off in the engine core, you might not even know about it until the next time the engine is stripped down for a full inspection.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-04-30T22:02:15.713" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14487" PostTypeId="2" ParentId="14462" CreationDate="2015-05-01T09:25:14.617" Score="9" Body="&lt;p&gt;The answer depends on the precise model of Boeing 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, the Boeing 747-8 (third generation of 747) features two beds which are clearly visible here, in blue:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qBZff.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;The original image of the complete aircraft is &lt;a href=&quot;http://www.flightglobal.com/Assets/GetAsset.aspx?ItemID=48502&quot; rel=&quot;nofollow noreferrer&quot;&gt;available here&lt;/a&gt;.&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The setup is very close to the one shown in &lt;a href=&quot;https://aviation.stackexchange.com/a/14485/2773&quot;&gt;fooot's answer&lt;/a&gt;. In the same way, Boeing 747-400 has two bed as well, as can be seen on &lt;a href=&quot;https://glennalexander.files.wordpress.com/2009/08/boeing-747-400.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;this schema&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the much older Boeing 747-300 doesn't seem to have any beds:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ljbkx.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;See the original &lt;a href=&quot;http://www.transaero.ru/wps/wcm/connect/4b0a678042799a5796effe1b2c6ee25b/747-300-VP-BGU.jpg?MOD=AJPERES&amp;amp;CACHEID=4b0a678042799a5796effe1b2c6ee25b&amp;amp;useDefaultText=1&amp;amp;useDefaultDesc=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;image here&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airlinereporter.com/2012/02/an-inside-look-at-the-boeing-747-stretched-upper-deck-sud/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Other sources&lt;/a&gt; (including &lt;a href=&quot;http://img716.imageshack.us/img716/8682/boeing747ebf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;the detailed 8300x3800 cutout of Boeing 747-100&lt;/a&gt;) confirm that there are apparently no beds on older Boeing 747-100, 747-200 or 747-300 models.&lt;/p&gt;&#xA;" OwnerUserId="2773" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-05-01T15:19:26.883" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14488" PostTypeId="2" ParentId="14327" CreationDate="2015-05-01T15:17:22.933" Score="4" Body="&lt;p&gt;An important concept here is &lt;a href=&quot;http://en.wikipedia.org/wiki/Dew_point&quot; rel=&quot;nofollow noreferrer&quot;&gt;dew point&lt;/a&gt;. The dew point temperature is related to the current temperature and the humidity of the air. For example, near sea level, a temperature of 51°F and humidity of 86% gives a dew point of 47°F. If air is cooled below the dew point, the water in the air will condense. You can see this effect on a cold glass; the air near the glass is cooled below the dew point, so the water in the air condenses onto the glass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When humidity is high, the dew point is very close to the air temperature, which is why it's easier to get condensation when the humidity is high. When the air temperature cools down to meet the dew point, fog forms. The water vapor in the air is condensing, but without a surface to gather on, it condenses into small droplets that form fog. Humidity will be high in foggy conditions, and often when it is raining, but can also be high in other circumstances. &lt;a href=&quot;https://aviation.stackexchange.com/questions/14327/what-is-the-mechanism-by-which-condensation-forms-above-wings#comment32127_14327&quot;&gt;Jan Hudec's comment&lt;/a&gt; notes that as water is evaporating from the wet ground, there can also be high humidity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/14331/1696&quot;&gt;Federico's answer&lt;/a&gt; does a good job of including the gas physics at work on the airplane wing. The important link is that as the wings create a low-pressure area, the temperature falls along with the pressure. If the dew point is high enough, this temperature drop may only need to be a few degrees. The water vapor condenses in the air, &lt;a href=&quot;https://youtu.be/dBjTnS-X8ik&quot; rel=&quot;nofollow noreferrer&quot;&gt;with the effect that you noticed&lt;/a&gt;. Once the air has passed over the wing, the pressure eventually returns to normal, along with the temperature, causing the water to evaporate again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The small &quot;contrails&quot; that form are from a similar effect. At locations such as the edges of flaps, a vortex is formed. This is a section of tightly spinning air. Similar to the wings, the acceleration of the air lowers its temperature and pressure, causing the condensation to form in the air. The vortex will eventually dissipate, and the condensation evaporates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual contrails that form behind planes at high altitudes are due to a similar but different effect, and there are &lt;a href=&quot;https://aviation.stackexchange.com/q/3539/1696&quot;&gt;some&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/q/3089/1696&quot;&gt;questions&lt;/a&gt; here discussing them.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-01T15:17:22.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14489" PostTypeId="2" ParentId="14470" CreationDate="2015-05-01T15:32:29.160" Score="2" Body="&lt;p&gt;David Eyerly was a cofounder of &lt;a href=&quot;http://en.wikipedia.org/wiki/Surf_Air&quot; rel=&quot;nofollow&quot;&gt;Surf Air&lt;/a&gt; in California. He was a graduate of Embry-Riddle held multiple ratings, and frequently flew the company's Pilatus PC-12s as PIC.&lt;/p&gt;&#xA;" OwnerUserId="8344" LastEditorUserId="65" LastEditDate="2015-05-01T16:06:11.573" LastActivityDate="2015-05-01T16:06:11.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14490" PostTypeId="1" AcceptedAnswerId="14515" CreationDate="2015-05-01T15:52:03.480" Score="6" ViewCount="5343" Body="&lt;p&gt;Besides the RAF is there a way of becoming a pilot without spending tens of thousands of pounds on flight training? I'm finishing university and looking to go into a career in flying, I can't join the RAF since I am partially colourblind so I would not be allowed to train as a pilot in the Air Force. &lt;/p&gt;&#xA;" OwnerUserId="8345" LastEditorUserId="12720" LastEditDate="2016-09-27T12:35:28.903" LastActivityDate="2016-09-27T12:35:28.903" Title="What is the least expensive way to become a commercial pilot in the UK?" Tags="&lt;career&gt;&lt;uk&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14491" PostTypeId="2" ParentId="14327" CreationDate="2015-05-01T17:22:02.293" Score="3" Body="&lt;p&gt;Federico's answer nails exactly what's going on, although for us Poetry majors, the graph can look confusing.  Let me add this simplified explanation, plus address something that showed up briefly in a now-deleted answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, condensation happens with cooling.  We see liquid condense on the side of a cold glass of liquid on a hot day, and happens when air &quot;here&quot; (near the glass) is cooled below the dewpoint, so the humidity condenses into water drops on the glass.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you see clouds/condensation/vapor trails forming above or directly behind the wing of an aircraft landing in humid conditions, the same basic phenomenon is taking place, but instead of condensing ONTO a surface, the condensation takes the form of a &quot;cloud&quot; or &quot;vapor trail&quot; streaming behind the wing.  Here, the cooling is caused by the air: with the air above the wing having lower pressure, it has cooled (PV=NRT, vaguely remembered from physics, &lt;strong&gt;P&lt;/strong&gt;ressure goes down, so does &lt;strong&gt;T&lt;/strong&gt;emperature), and when the air is humid enough with the spread between temperature and dewpoint very close, that cooling is enough to give you the condensation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar but distinct phenomena that causes condensation ON the wings, but not BEHIND them, is cold-soaked fuel.  When an aircraft has been flying at high altitude for a long time, where the temperatures are far below freezing (-40 degrees or so), the fuel inside the tanks in the wing gets cooled to similar temperatures.  On the ground, this fuel acts like the liquid in the glass, and you get condensation on the wings, and frequently, &quot;cold soaked fuel frost&quot; that forms after the condensation freezes onto the surface of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is NOT what causes the vapor trails observed in the original question, because there isn't enough time for the rushing air to be cooled by the cold wing.  THAT happens due to the change in air pressure.  Parked, you don't have the lift/low pressure, so that cooling mechanism is gone, but with stationary air, you have the other effect at work.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-01T17:22:02.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14492" PostTypeId="1" CreationDate="2015-05-01T17:44:38.040" Score="5" ViewCount="4543" Body="&lt;p&gt;I've noticed that the engines on the A320 make a very a distinct sound on takeoff. Is there something about the CFM-56 series that causes this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This noise can be heard in &lt;a href=&quot;https://youtu.be/2m9l-nDd1fw?t=1m40s&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="1696" LastEditDate="2015-05-01T18:54:40.450" LastActivityDate="2021-01-01T14:46:48.920" Title="Why do most A320s make that distinct scream on takeoff?" Tags="&lt;commercial-aviation&gt;&lt;takeoff&gt;&lt;airbus-a320&gt;&lt;noise&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14493" PostTypeId="1" AcceptedAnswerId="14502" CreationDate="2015-05-01T17:57:21.367" Score="12" ViewCount="3332" Body="&lt;p&gt;I believe the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-30&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sukhoi-30&lt;/a&gt; actually has 3 means of altering pitch and roll - canards, horizontal stabilizers, and thrust vectoring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fD09o.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fD09o.jpg&quot; alt=&quot;Sukhoi Su-30 Plan View&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image courtesy www.mars.slupsk.pl&lt;/sup&gt;&#xA;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the point of this? &lt;/li&gt;&#xA;&lt;li&gt;Does it lead to an increase in maneuverability?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="8282" LastEditDate="2019-01-18T14:55:05.340" LastActivityDate="2019-01-18T14:55:05.340" Title="Why does the Sukhoi-30 MKI have both canards and conventional horizontal stabilizers?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;maneuver&gt;&lt;pitch&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="14494" PostTypeId="1" AcceptedAnswerId="14497" CreationDate="2015-05-01T18:55:47.903" Score="31" ViewCount="4390" Body="&lt;p&gt;The FAA has &lt;a href=&quot;https://s3.amazonaws.com/public-inspection.federalregister.gov/2015-10066.pdf&quot;&gt;issued an airworthiness directive for the 787&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;SUMMARY&lt;/strong&gt;: We are adopting a new airworthiness directive (AD) for all&#xA;  The Boeing Company Model 787 airplanes. This AD requires a repetitive&#xA;  maintenance task for electrical power deactivation on Model 787&#xA;  airplanes. This AD was prompted by the determination that a Model 787&#xA;  airplane that has been powered continuously for 248 days can lose all&#xA;  alternating current (AC) electrical power due to the generator control&#xA;  units (GCUs) simultaneously going into failsafe mode. This condition&#xA;  is caused by a software counter internal to the GCUs that will&#xA;  overflow after 248 days of continuous power. We are issuing this AD to&#xA;  prevent loss of all AC electrical power, which could result in loss of&#xA;  control of the airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm curious: Are there any circumstances under which a 787 would remain powered continuously for 248 days?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Edited to add a follow-on question:]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has said &quot;If there is a definitive record of a powercycle within the last 120 days, no operator action is immediately required.&quot;  Does &lt;em&gt;that&lt;/em&gt; happen? 120 days?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the longest period a passenger aircraft might conceivably be continuously powered on?&lt;/p&gt;&#xA;" OwnerUserId="3037" LastEditorUserId="3037" LastEditDate="2015-05-01T19:25:15.297" LastActivityDate="2019-02-16T22:28:58.377" Title="In what circumstances could a 787 stay powered on continuously for 248 days?" Tags="&lt;software&gt;&lt;boeing-787&gt;&lt;airworthiness-directive&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14495" PostTypeId="1" AcceptedAnswerId="21193" CreationDate="2015-05-01T19:20:09.060" Score="5" ViewCount="8792" Body="&lt;p&gt;A few days ago, I applied for the position of Assistant Air Traffic Controller Officer (AATCO), for CAA in Pakistan. The next step is a written test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I supposed to prepare specifically?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My background is in software engineering. Any help/reference will be appreciated.&lt;/p&gt;&#xA;" OwnerUserId="8348" LastEditorUserId="62" LastEditDate="2015-05-01T19:57:19.603" LastActivityDate="2019-11-21T10:47:47.603" Title="Where can I get test samples for Assistant Air Traffic Controller Officer exam?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14496" PostTypeId="2" ParentId="14494" CreationDate="2015-05-01T19:21:03.633" Score="7" Body="&lt;p&gt;This is a bug Boeing found in the 787. This bug, which was &lt;a href=&quot;http://www.nytimes.com/2015/05/01/business/faa-orders-fix-for-possible-power-loss-in-boeing-787.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;found during laboratory testing&lt;/a&gt;, is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... plane’s power control units could shut down power generators if they were powered without interruption for 248 days, or about eight months&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This bug wasn't found in any airplanes in line operations. Boeing &lt;a href=&quot;http://www.nytimes.com/2015/05/01/business/faa-orders-fix-for-possible-power-loss-in-boeing-787.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;states&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... power was shut down in all airplanes in service in the course of the regular maintenance schedule ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airliners stay on for very long times, but their proper maintenance requires them to be power cycled regularly. About this issue, &lt;a href=&quot;http://www.theguardian.com/business/2015/may/01/us-aviation-authority-boeing-787-dreamliner-bug-could-cause-loss-of-control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If there is a definitive record of a powercycle within the last 120 days, no operator action is immediately required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, the answer to your question is &lt;em&gt;there aren't any&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="22726" LastEditDate="2019-02-16T22:28:58.377" LastActivityDate="2019-02-16T22:28:58.377" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="14497" PostTypeId="2" ParentId="14494" CreationDate="2015-05-01T19:26:51.203" Score="20" Body="&lt;p&gt;Aircrews seldom have to power off an aircraft completely (also known as a cold and dark cockpit). Airliners usually stay powered on at the gate. This is known as a &quot;short turn-around&quot;: engines are stopped, the APU is stopped, but electrical power and air conditioning is still supplied by ground equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has the advantage of minimizing turn-around time (after all, airliners are meant to stay in the air to make money). The cabin also has to be cleaned and prepared for the next flight at this time, so something must power the lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is &lt;em&gt;theoretically&lt;/em&gt; possible to stay on this way for 248 days. However, airliners have scheduled maintenance, which completely powers off the aircraft. They are also powered off if the expected time at the gate is long. So, in reality, it's &lt;em&gt;very unlikely&lt;/em&gt; to have an airliner powered continuously for 248 days.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="2691" LastEditDate="2015-05-01T20:55:24.873" LastActivityDate="2015-05-01T20:55:24.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14498" PostTypeId="2" ParentId="14494" CreationDate="2015-05-01T19:41:31.610" Score="15" Body="&lt;p&gt;There have been &lt;a href=&quot;http://www.bizjournals.com/wichita/morning_call/2015/05/faa-total-loss-of-power-a-risk-on-boeing-787.html&quot;&gt;issues&lt;/a&gt; with the 787 giving &quot;nuisance&quot; messages after starting up. One solution would be to start the process earlier, to leave time to deal with them. Another is to just never shut it down. However, the plane does need to be shut down sometimes for regular maintenance. &lt;a href=&quot;http://www.theguardian.com/business/2015/may/01/us-aviation-authority-boeing-787-dreamliner-bug-could-cause-loss-of-control&quot;&gt;A Boeing spokesperson said:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No airplane in the fleet experienced that condition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The issue was discovered during lab testing, and while it would be unusual for a plane to be on for 248 days straight, it's not impossible, so &lt;a href=&quot;http://en.wikipedia.org/wiki/Murphy%27s_law&quot;&gt;Murphy says&lt;/a&gt; that it will occur at &lt;a href=&quot;https://youtu.be/UV_vWtAJIow&quot;&gt;the worst possible time&lt;/a&gt;. So in the interest of safety, the FAA is making operators aware so that they can be sure to shut down their planes regularly and avoid the issue.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-01T19:41:31.610" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14499" PostTypeId="2" ParentId="14492" CreationDate="2015-05-01T20:38:02.747" Score="10" Body="&lt;p&gt;The whining noise is generated by the rotating components in the engine. At takeoff power for an engine of that size, the fan is rotating at about 5200 rpm. This is about 86 times per second. There are also 22 blades on the fan at the front of the engine. This means a given point sees a fan blade pass about 1900 times per second. Each fan blade changes the pressure as it passes, resulting in a tone of about 2kHz. This is the whine that you hear. At takeoff the tips of the fan blades are going supersonic, each one creating a shockwave.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-01T20:38:02.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14500" PostTypeId="1" CreationDate="2015-05-01T21:18:01.277" Score="12" ViewCount="3204" Body="&lt;p&gt;I just watched a recent AVWeb YouTube video about vinyl decals. In it the owner of Plane Decal says compared to paint, vinyl offers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;a more flexible choice of designs&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;a cheaper solution - a GA aircraft costing \$5,500 vs \$20-25k.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;a quicker install - 6.5 hours vs 6 weeks&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are these assertions correct? It leaves me wondering why aircraft are painted at all if this is the case? What are the cons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in both GA and commercial perspectives, since Bud mentions they've outfitted both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the video for those who are interested:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/8cqDO5baF5w?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="97" LastEditDate="2015-10-01T19:13:58.670" LastActivityDate="2015-10-01T19:13:58.670" Title="Why is most aircraft livery painted, rather than vinyled?" Tags="&lt;aircraft-design&gt;&lt;cost&gt;&lt;livery&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14501" PostTypeId="1" CreationDate="2015-05-01T21:48:33.117" Score="23" ViewCount="4887" Body="&lt;p&gt;I was just wondering if anyone could give me any info about this turbine rotating stage I picked up at a yard sale today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stage measures 8-1/2&quot; to the outside of the blades. The only markings I can find are TCYC5065 TT6776.0. It has 58 blades on the disk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qqjjW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qqjjW.jpg&quot; alt=&quot;Turbine disc&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8350" LastEditorUserId="3201" LastEditDate="2018-01-23T09:02:34.163" LastActivityDate="2019-11-08T16:04:06.133" Title="Can you identify this jet turbine stage?" Tags="&lt;jet-engine&gt;&lt;aircraft-identification&gt;&lt;turbine&gt;&lt;blade&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14502" PostTypeId="2" ParentId="14493" CreationDate="2015-05-01T22:19:07.420" Score="11" Body="&lt;p&gt;Yes, increased maneuverability and redundancy are the main benefits of this layout. Another is a wider possible range of the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the video linked in Federico's comment you can see that the canards reach high negative deflection angles in high-alfa attitudes: This means they will still operate in attached flow when wing and tail are already fully stalled. A canard-less airplane would only have thrust vectoring for control in this situation. Also noticeable in the video is the negative static stability which becomes evident in the lively elevator movements during the landing approach towards the end of the video. When you need agile pitch controls for artificial stability, it helps to have a second pair of them in highly dynamic maneuvers. The small size of the canards might be misleading: Since they will affect the flow over the inner wing, they are quite effective and powerful control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A multirole, long-range aircraft will have to deal with a wide variety of ordnance and fuel loads, so the addition of canards will allow to trim a wider range of c.g. positions. Without them, some load configurations, and consequently some missions, might not be possible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-02T11:31:51.560" LastActivityDate="2015-05-02T11:31:51.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14503" PostTypeId="2" ParentId="14475" CreationDate="2015-05-01T23:24:00.073" Score="1" Body="&lt;p&gt;Provided the engine survived the event, we are looking at all the engine parameters from the cockpit displays. Those indications are different depending on engine manufacturer. N1, N2, EGT, Oil pressure, ITT, engine vibrations indicator (VIB) and source, EPR (...). Just by looking at the numbers you cannot tell for sure if a blade separated. And it all depends also from the compressor stage the blade separated (first, last...) or if it was a fan blade.&lt;/p&gt;&#xA;" OwnerUserId="8331" LastActivityDate="2015-05-01T23:24:00.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14505" PostTypeId="2" ParentId="14402" CreationDate="2015-05-01T23:40:02.490" Score="3" Body="&lt;p&gt;Google: A380 Transport fluvial&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7r3I0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8331" LastEditorUserId="3049" LastEditDate="2015-05-02T01:51:12.197" LastActivityDate="2015-05-02T01:51:12.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14506" PostTypeId="2" ParentId="14490" CreationDate="2015-05-02T06:58:25.070" Score="3" Body="&lt;p&gt;There's a finite minimum set of requirements you must meet to get that ATPL and type ratings, and there's a finite minimum cost associated with that.&lt;br/&gt;&#xA;Nothing's going to change that. The only thing you can possibly, maybe, change is who is going to pay that money.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So don't fail any of the tests. The ONLY way to reduce the cost is to complete the training in as short a time as possible. Which means minimising flight hours, simulator hours, and retaking of courses. All of which boils down to passing every test first try.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And it will still take tens of thousands of pounds.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Going the Air Force route is also takes tens of thousands of pounds, except the air force (and thus other people, taxpayers) pick up part of the bill.&lt;br/&gt;&#xA;Same with every other scenario in which you're not paying everything yourself. Someone, somewhere, is paying for it.&lt;br/&gt;&#xA;Used to be (and maybe still is, but it's unlikely given the glut of unemployed pilots) some airlines would take on people and train them from scratch. But that's now rare. Most at the very least require you to have your PPL already, and many won't hire you unless you are qualified on at least some aircraft in their fleet.&lt;br/&gt;&#xA;&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-05-02T06:58:25.070" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14508" PostTypeId="1" AcceptedAnswerId="14513" CreationDate="2015-05-02T10:42:53.893" Score="13" ViewCount="31016" Body="&lt;p&gt;I am struggling to get my head around a concept that I believe should be fairly simple to understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift versus drag and AoA data of many airfoils are freely available, for instance the NACA 4-digit airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data is that of sectional, or 2D, lift and drag, or $C_l$ and $C_d$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if I were to build a 3D finite wing using a certain airfoil, how would I go about calculating the 3D coefficient of lift $C_L$?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that the aspect ratio $AR$ and Oswald efficiency factor $e$ come into play and that $C_D&amp;lt;C_d$ because of 3D effects such as tip leakage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, let's look at the NACA2412 airfoil: At $\alpha=8$ and at $Re=5.7e6$, it experiences $C_l=1$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I now manufacture a wing of $AR=7$ which has a planform giving an efficiency $e=0.8$, how would I go about calculating $C_L$?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any exact methods to calculate this or perhaps approximations?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="19" LastEditDate="2016-07-14T07:47:33.720" LastActivityDate="2017-05-07T10:46:43.190" Title="What is the method to calculate a finite wing's lift from its sectional airfoil shape?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;airfoil&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14509" PostTypeId="1" CreationDate="2015-05-02T14:14:17.877" Score="24" ViewCount="7358" Body="&lt;p&gt;The Concorde is powered by a bunch of Rolls-Royce/Snecma Olympus 593 turbojet engines. Much has been said about how efficient they are at speed, and the fact that they allow long-range cruise at Mach 2 because of how fuel-efficient they are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I look at the specifications, one thing immediately obvious is the compression ratio of 15.5 - quite high for a no-bypass turbojet. I'm not sure how this translates into efficiency though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust-specific fuel consumption, on the other hand, looks dismal. Wikipedia states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.195 lb/(lbf·h) (33.8 g/(kN·s)) cruise / 1.39 lb/(lbf·h) (39 g/(kN·s)) sl&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wait, what? The Tumansky R-25, which powered the MiG-21 and was famously fuel-hungry, had a compression ratio of only 9.5, but had a TSFC of &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;98 kg/(h·kN) (0.96 lb/(h·lbf)) at maximum military power&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The General Electric YJ93, which powered the XB-70 and was also designed for long-range supersonic efficiency, had a TSFC of&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;0.700 lb/(lbf·h) or 19.8 g/(kN·s)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This doesn't seem to make sense: in what way are Concorde's engines any good? Is there something I'm missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I've been attempting to model the Olympus 593 in a flight simulator (Advanced Jet Engine in KSP). With the given compression ratio, though, I couldn't get the fuel efficiency to be this bad: it was around 0.9 SL and 0.85 cruise, and I had to do ridiculous things like using extremely inefficient intakes and nozzles.&lt;/p&gt;&#xA;" OwnerUserId="8357" LastEditorUserId="2150" LastEditDate="2015-05-04T23:43:32.133" LastActivityDate="2017-10-27T21:29:57.463" Title="In what way are the Concorde's engines considered efficient?" Tags="&lt;jet-engine&gt;&lt;concorde&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14510" PostTypeId="2" ParentId="14396" CreationDate="2015-05-02T14:49:54.973" Score="-2" Body="&lt;p&gt;US Army had a special type of nuclear explosive, they called: 'Demolition weapon',  or something like, its power was in the range of kilotons, had a weight of around 60 kg (133 pounds), and was discontinued by 1950. So, you can drop a nuclear weapon, if you have it, from any two seat ultralight airplane, and escape if you fly high enough. Plutonium can be obtained from a homemade reactor not bigger than a metal grain silo, they had one like this in the Barcelona University. &#xA;Fighting airplanes' technology is to ultralight aircraft what Formula 1 cars technology is to mopeds, it's hard to imagine that the aerial nuclear war procedures and capabilities are known to anybody out some restricted military audiences, and the features and performances of airplanes able to carry and launch nuclear weaponry can be watched at air shows and specialized publications, the USSR said that most of the technology information they got from the free world came from open access and purchase publications, probably, no government will sell a military technology to a third party if they don't have in reserve at home something better, it would be silly selling a technology that someone could use against you, as the experience is that big changes in government's lines are a true possibility&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-05-03T22:30:40.223" LastActivityDate="2015-05-03T22:30:40.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14513" PostTypeId="2" ParentId="14508" CreationDate="2015-05-02T16:43:45.833" Score="7" Body="&lt;p&gt;2D is a simplification of real life... it's very difficult to translate something 2D to something 3D. However there are approximations but I can tell you that no exact method is available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the key components of drag that you are missing in 2D is the induced drag, which is the drag generated by a wing simply because it has a finite dimension. The difference in circulation created by each airfoil has an influence over the complete wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a theory which is linear and non-viscous that helps to compute the aerodynamic components of the wing, based on the aerodynamic characteristics of the airfoils the wing is made of. It also allows you to create twist. It is subject to simplifications such as as being linear and missing viscosity, but it provides a very good approximation for the effort (analytical for a significant amount of cases, and excel does the work for others).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The theory is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting-line_theory&quot; rel=&quot;nofollow noreferrer&quot;&gt;lifting-line theory&lt;/a&gt; and what you just need to is: add the induced drag provided by the theory (you don't have it in your airfoil):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\ C_{D_i} = \frac{{C_L}^2}{\pi \text{AR} e} $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to know the planform for being able to make the integral of your wing, but the following equation will save you some time:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ \ C_{L3D} = C_{l_\alpha} \left( \frac{\text{AR}}{\text{AR}+2} \right) \alpha$ &lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="21091" LastEditDate="2017-05-07T10:46:43.190" LastActivityDate="2017-05-07T10:46:43.190" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="14514" PostTypeId="2" ParentId="14509" CreationDate="2015-05-02T17:21:41.730" Score="7" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;In what way are the Concorde's engines considered efficient?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h2&gt;TSFC/Speed&lt;/h2&gt;&#xA;&lt;p&gt;The Wikipedia article, &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption#Significance_of_SFC&quot; rel=&quot;noreferrer&quot;&gt;&amp;quot;Thrust specific fuel consumption&amp;quot;&lt;/a&gt;, referred to in the question, says&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;although the nominal SFC is a useful measure of fuel efficiency, it should be divided by speed to get a way to compare engines that fly at different speeds.&lt;/p&gt;&#xA;&lt;p&gt;For example, Concorde cruised at Mach 2.05 with its engines giving an SFC of 1.195 lb/(lbf·h) (see below); this is equivalent to an SFC of 0.51 lb/(lbf·h) for an aircraft flying at Mach 0.85, which would be better than even modern engines; it was the world's most efficient jet engine.[2][3]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I think what they are saying is perhaps that the amount of &lt;a href=&quot;http://en.wikipedia.org/wiki/Work_(thermodynamics)&quot; rel=&quot;noreferrer&quot;&gt;thermodynamic work&lt;/a&gt; being produced per unit quantity of fuel was high. Concorde was cruising at Mach 2 and had a range of 7000 km. There probably aren't many aircraft around that need to do that. It's engines were producing a &lt;em&gt;lot&lt;/em&gt; more work than a typical high-bypass turbofan attached to a widebody jet at Mach 0.85 does.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Thermal Efficiency&lt;/h1&gt;&#xA;&lt;p&gt;They are considered to have high &lt;em&gt;&amp;quot;thermal efficiency&amp;quot;&lt;/em&gt; &lt;strong&gt;at Mach 2&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;They are considered inefficient at lower speeds.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The Rolls-Royce Olympus 593 Mk 610 installed in Concorde STILL remains the most efficient jet engine in the world at Mach 2, as far as thermal efficiency is concerned. This is due to the design of the engine itself of course, but mainly down to the intake, and to a lesser extent the individual nozzle designs. ... (As efficient as the OLY 593 is at Mach 2 and about, at slower speeds it uses fuel like it’s going out of fashion, hence the need for a minimum of low speed flying with Concorde).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.saveconcordegroup.co.uk/engines/&quot; rel=&quot;noreferrer&quot;&gt;a bunch of Concorde enthusiasts&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Specific Impulse&lt;/h1&gt;&#xA;&lt;p&gt;Another way to measure engine efficiency is specific impulse&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0pRIE.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;Graph by &lt;a href=&quot;http://en.wikipedia.org/wiki/Specific_impulse#/media/File:Specific-impulse-kk-20090105.png&quot; rel=&quot;noreferrer&quot;&gt;Kashkhan&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-02T20:32:04.300" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14515" PostTypeId="2" ParentId="14490" CreationDate="2015-05-02T21:55:08.847" Score="2" Body="&lt;p&gt;It looks like British Airways may still offer their &lt;a href=&quot;https://jobs.ba.com/jobs/futurepilot/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Future Pilots program&lt;/a&gt;, which Danny Beckett mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/a/3463/755&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possible option would be to move to another (probably non-Western) country for a while. Southeast Asia in particular is experiencing a large amount of growth in airline traffic and seems to hire lots of American, Australian, and European pilots, so you might be more likely to find openings in a program there that would cover the cost. The Middle East might also be an option, given their current huge growth in airline traffic, though I'm not sure what their hiring policies are like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cathay Pacific is an example of such a program in Southeast Asia. Among &lt;a href=&quot;http://www.cathaypacific.com/cx/en_HK/about-us/careers/jobs-in-the-air/pilots.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;their listed programs for hiring flight crew&lt;/a&gt; is their &lt;a href=&quot;http://jobsatcathaypacific.com/cadetpilots/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cadet Pilot Programme&lt;/a&gt;. They hire people from all over and send them to a flight training school in Australia. I remember them even advertising this program on the plane the last time I flew with them (a couple of years ago.) Being a former British colony, someone from the U.K. would probably fit in well there. I think every pilot I had on my last trip with them was either American, British, or Australian. Seems like it would be a fun airline to fly for, too, if you were ok with moving to Hong Kong for at least whatever their commitment period is. With the vast majority of their flights being international on wide-bodies, you'd likely get to heavy jets much more quickly than you would in Europe or, especially, the U.S.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One additional thing to note, though, as I mentioned in my comment earlier, if you don't meet RAF's requirements due to your eyesight, you may also have trouble getting the necessary medical certificate for an Airline Transport Pilot license, especially in Europe or the U.S. It turns out the EASA's requirement's regarding color vision are pretty much identical to the ones I mentioned in my comment earlier regarding FAA standards. &lt;a href=&quot;http://www.caa.co.uk/Aeromedical-Examiners/Medical-standards/Pilots-(EASA)/Conditions/Visual/Colour-vision-guidance-material-GM/&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to the UK CAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Applicants shall be required to demonstrate the ability to perceive readily the colours that are necessary for the safe performance of duties.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Examination&lt;br&gt;&#xA;     (1) Applicants shall pass the Ishihara test for the initial issue of a medical certificate.&lt;br&gt;&#xA;     (2) Applicants who fail to pass in the Ishihara test shall undergo further colour perception testing to establish whether they are colour safe.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) In the case of class 1 medical certificates, applicants shall have normal perception of colours or be colour safe.  Applicants who fail further colour perception testing shall be assessed as unfit. Applicants for a class 1 medical certificate shall be referred to the licensing authority.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-09-27T03:29:43.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14516" PostTypeId="2" ParentId="14509" CreationDate="2015-05-02T23:28:13.343" Score="9" Body="&lt;p&gt;Wikipedia article on &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption&quot; rel=&quot;nofollow noreferrer&quot;&gt;thrust specific fuel consumption&lt;/a&gt; actually uses Concorde as example, probably because it was such an extreme case. I probably should edit to make a this a real answer,but since they use your specific question as example I will just quote.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;SFC varies with throttle setting, altitude and climate. For jet&#xA;engines, flight speed also has a significant effect upon SFC; SFC is&#xA;roughly proportional to air speed (actually exhaust velocity), but&#xA;speed along the ground is also proportional to air speed. Since work&#xA;done is force times distance, mechanical power is force times speed.&#xA;Thus, although the nominal SFC is a useful measure of fuel efficiency,&#xA;it should be divided by speed to get a way to compare engines that fly&#xA;at different speeds.&lt;/p&gt;&#xA;&lt;p&gt;For example, Concorde cruised at Mach 2.05 with its engines giving an&#xA;SFC of 1.195 lb/(lbf·h) (see below); this is equivalent to an SFC of&#xA;0.51 lb/(lbf·h) for an aircraft flying at Mach 0.85, which would be better than even modern engines; it was the world's most efficient jet&#xA;engine.[2][3] However, Concorde ultimately has a heavier airframe, and&#xA;due to being supersonic is less aerodynamically efficient, i.e., the&#xA;lift to drag ratio is far lower. In general the total fuel burn of a&#xA;complete aircraft is of far more importance to the customer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;My personal interpretation as a total layperson of this is that the original air speed target was higher than the air speed of Concorde because the issues of supersonic flight were underestimated. Because of those issues the actual Concorde was built for &lt;strong&gt;only&lt;/strong&gt; Mach 2 or so. The engine design was still influenced by that original airspeed target (whatever that was) and as a result had higher exhaust velocity than actually was necessary. This resulted in higher fuel consumption and noise. The reduced range and increased noise in turn limited the routes Concorde could fly and the areas where the supersonic flight could be used. Which made Concorde commercially a &amp;quot;limited&amp;quot; success and made upgrading the engines to ones optimized for the actual speed commercially impractical.&lt;/p&gt;&#xA;&lt;p&gt;Note that the above is my speculation of the background. The important part is that the exhaust speed of the engines is faster than necessary for the Concorde. This means that despite good thermal and energy efficiency, thrust efficiency is lower than necessary&lt;/p&gt;&#xA;&lt;p&gt;So yes, the engines were uneconomical and suffered from excessive noise and fuel consumption, but that was due to the airframe and engine being optimal for different speeds. The engines were quite efficient, best thermal efficiently achieved at the time, they just were optimized for the wrong speed that in practice was not achieved.&lt;/p&gt;&#xA;" OwnerUserId="4472" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-06T09:56:58.990" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14517" PostTypeId="2" ParentId="14492" CreationDate="2015-05-02T23:38:19.730" Score="2" Body="&lt;p&gt;Unfortunately I am unable to watch your video at the moment so I can't say for sure that this is the noise you are hearing, but you have commented that the noise is a whine and not engine buzz. The A320 series is known for having a distinct whine, essentially caused by the pressure equalisation vents for the fuel tanks, which are open to the external airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Lufthansa describe &lt;a href=&quot;http://www.lufthansagroup.com/nc/en/press/news-releases/singleview/archive/2013/october/29/article/2651.html?cHash=1a95de435ac238204a1b5df047c9a7f7&amp;amp;sword_list%5B0%5D=vortex&amp;amp;sword_list%5B1%5D=generator&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, the effect is the same as when you blow over the mouth of a bottle. Lufthansa are retrofitting vortex generators  on their A320s in order to reduce this whine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some more interesting reading on this issue is &lt;a href=&quot;http://www.airportwatch.org.uk/2014/11/lufthansa-retrofitting-a320-family-with-simple-inexpensive-noise-reducing-device-to-stop-the-airbus-whine/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.euractiv.com/sections/aviation/small-beautiful-how-tiny-device-cuts-aircraft-noise-303505&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2015-05-02T23:45:29.037" LastActivityDate="2015-05-02T23:45:29.037" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14518" PostTypeId="2" ParentId="14493" CreationDate="2015-05-02T23:54:25.113" Score="6" Body="&lt;p&gt;Be careful of confusing manoevrability and agility. The former describes turn performance (min radius, max sustained turn rate etc), while agility describes how quickly it can change manoeuvre state; depends on stability, handling qualities, control power etc. Given this design is based on a legacy version, the large moments of inertia in pitch demand greater control power to achieve the agility required of modern fighter, especially in the post stall/high AoA regime. Also, as mentioned, better control power at higher AoA facilitates relaxed stability longitudinally, which in turn improves agility and possibly handling qualities, depending on how it is implemented through the flight control system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some fighters, one I can think of, differential use of canards can be used to increase directional control power as the pressure differential across the fuselage helps to pull the nose around. This is useful at high AoA where yaw, not roll, is predominant wrt aircraft axes when changing lift vector direction.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastEditorUserId="8030" LastEditDate="2015-05-03T00:07:01.340" LastActivityDate="2015-05-03T00:07:01.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14519" PostTypeId="1" AcceptedAnswerId="14523" CreationDate="2015-05-03T00:04:28.313" Score="10" ViewCount="1360" Body="&lt;p&gt;My understanding of &lt;a href=&quot;http://en.wikipedia.org/wiki/Continental_Express_Flight_2574&quot;&gt;Continental Express flight 2574&lt;/a&gt; is that a de-icing boot on the horizontal stabilizer of the EMB120 was missing screws and therefore detached, leading to the tail separating. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would appreciate an explanation, with as much aerodynamic information as necessary, for how the tail separation could be caused by the boot removal.  &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="923" LastEditDate="2015-05-03T00:17:56.930" LastActivityDate="2015-05-03T01:28:49.470" Title="How did flight 2574 break up?" Tags="&lt;aerodynamics&gt;&lt;accidents&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14520" PostTypeId="1" AcceptedAnswerId="14524" CreationDate="2015-05-03T00:57:35.060" Score="21" ViewCount="3617" Body="&lt;p&gt;Are wheel brakes on most commercial jet airliners capable of holding the jet stationary on a dry surface, if all the engines are given full thrust? Could doing this be potentially unsafe or damaging to any of the aircrafts other structures,  such as pylons, wings, etc.  &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="97" LastEditDate="2015-05-03T01:20:44.150" LastActivityDate="2015-05-03T10:51:59.767" Title="Can the wheel brakes hold an airliner in place if its engines are at full thrust?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14521" PostTypeId="1" AcceptedAnswerId="14533" CreationDate="2015-05-03T01:09:52.957" Score="6" ViewCount="901" Body="&lt;p&gt;Is it possible to use ONLY thrust reversers to steer and bring a smaller size commercial jet aircraft, with a minimum amount of fuel onboard, to a complete stop, after touching down on a longer than average length commercial airport runway?&lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="97" LastEditDate="2015-05-03T15:38:55.040" LastActivityDate="2015-09-23T14:49:37.977" Title="Can thrust reversers alone steer and stop an airliner?" Tags="&lt;airliner&gt;&lt;aircraft-performance&gt;&lt;thrust-reverser&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14522" PostTypeId="1" AcceptedAnswerId="14525" CreationDate="2015-05-03T01:23:35.513" Score="15" ViewCount="1703" Body="&lt;p&gt;Currently what models of commercial aircraft are capable of landing and safely stopping the aircraft, without any human assistance, other than inputting instructions to the onboard computers. &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="97" LastEditDate="2015-05-03T01:26:47.853" LastActivityDate="2015-05-03T10:02:06.137" Title="Which commercial aircraft are capable of computer-only landings, without human assistance?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;commercial-aviation&gt;&lt;autopilot&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14523" PostTypeId="2" ParentId="14519" CreationDate="2015-05-03T01:28:49.470" Score="13" Body="&lt;p&gt;It didn't directly lead to the tail separating. What separated wasn't just the de-ice boot, it was the whole leading edge on the left stabilizer. That caused a stall of the left horizontal stabilizer and an increase in drag on the left side. The wings of an aircraft have a tendency to pitch the aircraft down (as they're behind the center of gravity and provide a force upwards), while the stabilizer produces a force downwards to keep the plane's pitch stable. With the loss of lift on the left stabilizer, there was less downforce (leading to a pitch down), more downforce on the right than on the left (leading to a right roll), and more drag on the left than the right (leading to left yaw).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These rather violent motions led to massive aerodynamic loads on the plane, resulting in the next failure: the left wing. When this failed, the plane violently rolled right, for reasons I'm not quite sure of (I get violently rolling, but am unsure why it was to the right). This roll stressed the plane even more, and &lt;em&gt;that&lt;/em&gt; is when the tail ripped off the plane. The direct cause was extreme aerodynamic forces caused by the flight path, not the leading edge separation itself.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-05-03T01:28:49.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14524" PostTypeId="2" ParentId="14520" CreationDate="2015-05-03T01:45:09.367" Score="22" Body="&lt;p&gt;Yes they are. In fact this is required for a &lt;em&gt;static takeoff&lt;/em&gt;. A static take-off means setting the brakes and running up the engines to takeoff power then when ready they release the brakes and start the takeoff roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides that one of the test Airliners have to withstand is a worst-case V1 abort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means starting a takeoff and at the last second slam the brakes, come to a stop and then taxi around for 5 minutes. This all needs to happen fully-loaded and with worn brakes that are still certified safe to use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between hitting the brakes and coming to a stop the engines will not have time to spool down and stop providing takeoff power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliner mechanics also do engine run-up tests essentially powering up the engine and going through the power range and making sure it works as specified. This is usually 1 engine at a time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these run-up tests loose debris (including cars) can be thrown around by the engine blast. So it's important to keep the area clear. &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-05-03T01:53:04.037" LastActivityDate="2015-05-03T01:53:04.037" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14525" PostTypeId="2" ParentId="14522" CreationDate="2015-05-03T02:22:27.570" Score="22" Body="&lt;p&gt;None. While a number of aircraft are certified for autoland with automatic rollout until safe taxi speed, and some can have the autopilot control rollout until the aircraft completely stops, no commercial aircraft has autopilot control of various critical parts for landing such as the flaps and the landing gear.&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-05-03T02:22:27.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14526" PostTypeId="2" ParentId="391" CreationDate="2015-05-03T08:13:15.763" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Uncontrolled cabin fires only need a few minutes to spread throughout the cabin of an aircraft, killing everyone onboard and destroying the airframe.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, how do you get an uncontrolled cabin fire? It starts with a cabin fire that the crew notice and try to control, and then ultimately fail to control after many minutes of trying. In those minutes the pilot has hopefully descended from altitude and is nearing an emergency landing site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there's a fire on a passenger plane, pilots are expected to land ASAP so everyone can get away from the blazing inferno. That makes good sense to me.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So if an aircraft had a way to depressurize the cabin and eliminate oxygen in the event of a fire, the fire would be extinguished, saving lives.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Except this &quot;solution&quot; requires the pilot to stay at altitude when there is a cabin fire, so that de-pressurization will be effective. Contrasted with the alternative of descending to have a chance at making an emergency landing, I'd have to say that the latter seems much more likely to save lives to me.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I know that depressurization is dangerous but there is a better chance of surviving a depressurization than surviving flames.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would say it's probably a more pleasant way to die, but doesn't have much going for it apart from that. The fire is much more likely to be slowed rather than stopped, and you can't survive at high altitude forever (even with those silly oxygen mask things). The fire would be back at full strength once you descended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, once people are dependent on the oxygen masks for consciousness, it prevents them from simply reshuffling to areas of the plane that the flames haven't reached yet. Besides, by the time the fire got bad enough that you'd even consider a measure as extreme as de-pressurizing the cabin at altitude, many people would probably already have re-shuffled away from the flames and there wouldn't be enough oxygen masks for everyone in the non-flaming section of the plane.&lt;/p&gt;&#xA;" OwnerUserId="8368" LastActivityDate="2015-05-03T08:13:15.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14529" PostTypeId="1" AcceptedAnswerId="14530" CreationDate="2015-05-03T12:08:48.913" Score="14" ViewCount="1147" Body="&lt;p&gt;The crash of &lt;a href=&quot;https://en.wikipedia.org/wiki/Continental_Express_Flight_2574&quot; rel=&quot;nofollow noreferrer&quot;&gt;Continental Express flight 2574&lt;/a&gt; in 1991 (see also &lt;a href=&quot;https://aviation.stackexchange.com/q/14519/946&quot;&gt;this question&lt;/a&gt;) was caused by faulty maintenance to the de-icing boot on the left horizontal stabilizer. This became detached in flight, leading to violent movements of the plane which caused the left wing to fail and the right wingtip to detach.  Ultimately, the horizontal part of the T-tail detached and the plane crashed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.airdisaster.com/reports/ntsb/AAR92-04.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NTSB report&lt;/a&gt; says (page&amp;nbsp;34, with essentially the same statement repeated on page&amp;nbsp;37):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane then rolled to the right at a roll rate exceeding&#xA;  160 degrees per second. The Safety Board believes that the lift produced by the&#xA;  intact right wing produced the extreme roll.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The report also says that the initial failure of the left stabilizer caused a 10&amp;ndash;15&amp;deg; roll to the right, which makes sense: the loss of downforce from the stabilizer meant the left side of the plane was generating more net lift than the right. But how would the subsequent failure of the left wing produce a roll to the right? The natural assumption would be that, with the right wing generating lift and the left wing not, the plane would roll to the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possibly relevant is that the left wing failed but didn't detach from the plane: the plane crashed right-way-up with the left wing folded under the fuselage and the inboard portion of the right wing.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-04T07:32:16.703" Title="How could a failed left wing cause a roll to the right?" Tags="&lt;accidents&gt;&lt;flight-controls&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14530" PostTypeId="2" ParentId="14529" CreationDate="2015-05-03T12:56:48.927" Score="15" Body="&lt;p&gt;The following is how I would interpret the information given in the report - this is to some extent speculation, also because the FDR plots in the report don't seem to cover that part of the incident. I'm very intersted in how other people interpret the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airframe remained intact (minus the leading edge), and the load&#xA;  factor fluctuated around -2 g, for approximately 6 l/2 seconds. [...] airplane heading moved 20 degrees nose left, and a 15 degree right roll attitude was reached at the end of this period.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The fact that the left leading edge of the stabilizer was lost and that the heading is moving left makes me believe that the aircraft was in some kind of a slip with the right wing further forward in the wind. The negative load factor of -2 g indicates a lot of negative load on both wings - apparently more than the structure tolerated. Both wings &quot;stalled negatively&quot;&lt;sup&gt;1&lt;/sup&gt; at this point. Now if one wing goes missing (aerodynamically, even if not physically), it can't provide the downforce any more and the total momentum will cause the side of the aircraft where there is still a functioning wing to rotate down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the right wing was probably pointing slightly forward (even more so if the left wing produced a lot of drag while or after failing, which seems likely), a roll to the right would make the aircraft more or less tumble over its own wing, with the wing upper surface pointing increasingly towards the airflow around a 90° right roll position. The resulting drag explains a very fast roll to a ~180° position. Starting from &quot;10 to 15 degrees right wing down&quot;&lt;sup&gt;2&lt;/sup&gt;, that's about 160°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short version: Because the wings had negative load and were primarily drag surfaces at this point, everything is reversed. The side of the aircraft with less drag rolled towards the incoming airflow. In a negative angle of attack attitude, that's up in the aircraft coordinate system, causing a roll to the right.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; 3.1: Findings; 7. p. 48 (56 in pdf)&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt; p. 20 (28 in pdf)&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="6919" LastEditDate="2015-05-04T07:32:16.703" LastActivityDate="2015-05-04T07:32:16.703" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14531" PostTypeId="1" CreationDate="2015-05-03T13:59:24.603" Score="1" ViewCount="237" Body="&lt;p&gt;For example, E190s are produced in Brazil but operate in places like Germany, China, etc. Surely they can't fly these distances, so how are they delivered?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastEditorUserId="1467" LastEditDate="2015-06-12T19:23:30.900" LastActivityDate="2015-06-12T19:23:30.900" Title="How are regional planes delivered?" Tags="&lt;general-aviation&gt;&lt;range&gt;&lt;ferry-flight&gt;&lt;aircraft-purchase&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-05-03T14:41:35.780" ContentLicense="CC BY-SA 3.0" />
  <row Id="14533" PostTypeId="2" ParentId="14521" CreationDate="2015-05-03T16:24:26.780" Score="9" Body="&lt;p&gt;Steer: No. Stop: Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust reversers are either in or out. They cannot be engaged proportionally to some control setting in the cockpit. Once they are unlocked, the airflow through them sucks them out completely. The only way to vary their braking effect would be to throttle the engine up or down, and airliner engines react rather sluggishly to control inputs. Their responsiveness will not suffice to steer the aircraft; only rudder inputs (and those only at higher speed), nose wheel steering and differential braking with the wheel brakes are suitable for directional control on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their braking effect is biggest at high speed and tapers off as the aircraft decelerates. For the first third of the landing run they will help noticeably in slowing the aircraft, but you will need a long runway when you want to land without wheel brakes. Details depend on landing weight, airfield elevation and wind speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-23T14:49:37.977" LastActivityDate="2015-09-23T14:49:37.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14534" PostTypeId="2" ParentId="14521" CreationDate="2015-05-03T16:44:08.563" Score="4" Body="&lt;p&gt;From a physics perspective, we can calculate the amount of force needed to slow a plane down within a given distance. The stopping distance equation is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$d_f=\frac{v_i^2}{2a}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume the plane has 7000 ft to stop with only reverse thrust, and the touchdown speed is 130 knots = 220 ft/s, we can solve for acceleration.&lt;br&gt;&lt;sub&gt;All calculations will be approximate&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$7000=\frac{220^2}{2a}$$&#xA;$$a=3.5 ft/s^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the second law of motion, we can find the force required to decelerate a 120,000 lb airplane at that rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$F=ma$$&#xA;$$F=120,000\times3.5=415,000ftlb/s^2=13000lbf$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is about 25% of the max forward thrust of a 737-700. The engines have a bypass ratio of over 5:1, so it seems reasonable that the engines should be able to average this amount of reverse thrust force. This estimate also ignores all effects of drag or friction that would also help to stop the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For steering, the pilots could use differential thrust. It would be more difficult than using the rudder and nose wheel, but it should be sufficient. A sideways wind component would make it more difficult to steer though.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-03T16:44:08.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14535" PostTypeId="1" AcceptedAnswerId="14544" CreationDate="2015-05-03T19:56:05.817" Score="15" ViewCount="2870" Body="&lt;p&gt;When 3 man cockpits were common place on commercial aircraft what was the career progression of a Flight Engineer like?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did FE's normally transition to be pilots? I'm not trying to insinuate here that FE's were in anyway inferior to the pilots and of course some FE's would of had no desire to transition to a pilot capacity at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Were there any airlines who operated a policy of starting flight crew out as a FE then training them as pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;N.B&lt;/strong&gt; - Some background information that I'm basing this question on is I've read a number of reports regarding young (early 20 y/o FE's becoming pilots) and in maybe a more extreme case the hijacking of &lt;a href=&quot;http://en.wikipedia.org/wiki/Federal_Express_Flight_705&quot;&gt;FedEx Flight 705&lt;/a&gt; when the FE who hijacked the aircraft (an ex-Naxy pilot) had been made a FE (this could be part due to the fact he apparently falsified his Navy flying hours).&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="97" LastEditDate="2015-05-03T23:42:12.833" LastActivityDate="2015-05-04T06:01:06.743" Title="Did Flight Engineers progress to be pilots?" Tags="&lt;commercial-aviation&gt;&lt;pilots&gt;&lt;aviation-history&gt;&lt;career&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14536" PostTypeId="1" AcceptedAnswerId="14553" CreationDate="2015-05-03T22:00:25.443" Score="13" ViewCount="12370" Body="&lt;p&gt;I remember listening to the on-board program with headphones that consisted of hollow hoses as a kid. You plugged them into small holes in the arm-rests. The program was the same for everybody.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was the system in place? Why was it phased out?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="97" LastEditDate="2015-05-03T23:43:45.563" LastActivityDate="2021-05-11T00:56:25.267" Title="Why were there pneumatic headphones on airliners in the 70's and 80's?" Tags="&lt;aviation-history&gt;&lt;inflight-entertainment&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14538" PostTypeId="1" AcceptedAnswerId="14545" CreationDate="2015-05-03T23:43:30.037" Score="11" ViewCount="18555" Body="&lt;p&gt;I'm trying to figure out the lift coefficient of an A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm doing is the following: during cruise, the lift is equal to the weight of the aircraft ($mg$) so that I used the cruise table taken from the FCOM to get the speed, the wing area is known ($122.6 m^2$) and I calculated using a &lt;a href=&quot;http://aero.stanford.edu/stdatm.html&quot; rel=&quot;noreferrer&quot;&gt;tool online&lt;/a&gt; the air density at FL290 (29,000 ft).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/l9g9N.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The result is that the lift coefficient is $0.03029$. Is it right for the assumptions given above?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, if I want to relate the $C_L$ with the Angle of Attack, what is the formula and the procedure?&lt;/p&gt;&#xA;" OwnerUserId="8374" LastEditorUserId="97" LastEditDate="2015-05-03T23:48:20.103" LastActivityDate="2018-03-14T09:45:45.113" Title="How to calculate the Lift Coefficient for the A320?" Tags="&lt;airbus-a320&gt;&lt;lift&gt;&lt;performance-calculation&gt;&lt;angle-of-attack&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14539" PostTypeId="1" AcceptedAnswerId="14546" CreationDate="2015-05-04T00:02:49.267" Score="28" ViewCount="36002" Body="&lt;p&gt;What is the source for what looks to be small trails of smoke or condensation sometimes coming from the very tips of a jet aircrafts wing tips? &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="97" LastEditDate="2015-05-04T00:06:58.673" LastActivityDate="2020-03-09T04:33:56.280" Title="What causes a plane's wing tips to leave a small white vapor trail?" Tags="&lt;aircraft-design&gt;&lt;weather&gt;" AnswerCount="3" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14540" PostTypeId="2" ParentId="14396" CreationDate="2015-05-04T00:18:46.447" Score="2" Body="&lt;p&gt;Primary requirements for delivery of Nuclear weapons beyonds the physical ability to transport the munition is the Arming and Fuzing capability. This extends to Authorization and control operations of the device, safety is integrated in each section and independently also.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example control and authorization required interface via a PAL (Permissive Action Links) This is a physical device, combination lock or a electronic keypad-activated interlock.The intent is to prevent detonation without direct positive action instructing such.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along with the ESD systems which are another set of safety systems the aircraft must be able to communicate and execute the require actions demanded of the bombs safety operations SOPS and systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the the only requirements to carry nuclear weapons and basically covered in the below areas.  Due to their awesome power and demands of failsafe carriage n flawless detonation (else the enemy can utilize the undetonated weapon) additional delivery platform hardware is required as for smart weapons of conventional types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also regarding the F-35, the air force intends these to be dual capable and will work to ensure its compatibility with the BP61 replacing F15 &amp;amp; F16 in this assignment. &lt;/p&gt;&#xA;" OwnerUserId="8375" LastEditorUserId="8375" LastEditDate="2015-05-04T02:59:52.637" LastActivityDate="2015-05-04T02:59:52.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14541" PostTypeId="2" ParentId="14539" CreationDate="2015-05-04T00:50:10.530" Score="25" Body="&lt;p&gt;The cause is reduced pressure in the wingtip vortex trailing behind the wing. Reduced pressure causes reduced temperature and if ambient humidity is high enough the result is the  condensation you observe. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-05-04T00:50:10.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14544" PostTypeId="2" ParentId="14535" CreationDate="2015-05-04T05:00:36.973" Score="19" Body="&lt;p&gt;Before the turn of the century (I can't believe I'm using that phrase, as I retired in 1999) and especially back when all 3 engine and 4 engine airliners had a flight engineer, the usual career path at many airlines was to hire in as an Flight Engineer, or FE (two stripes), progress to an First Officer, or FO (three stripes), and then become a captain (four stripes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all began to change, of course, with the advent of large 2-man cockpit aircraft. The change was not without controversy and some pain. For example, at least one initial operator of the 737 ran a 3-man cockpit for a time. The 3rd guy was, as I remember, referred to as the GIB (guy in back). He sat in the jumpseat and read the checklists, which was one of the tasks an FE typically had in 3-man cockpits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it happened, the two jet carriers I worked for hired pilots into the FO seat and used professional FEs. I spent a couple of years on the 727 and then 10 years on the 747.  During that time, every FE save one that I flew with was ex-military, and with few exceptions all were A&amp;amp;Ps. That was desirable in case a maintenance sign off was needed when you were someplace where maintenance was not otherwise available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Occasionally you would encounter an FE who had been a captain.  The pilots were required to retire at 60 back then, but FEs weren't.  I only knew one such individual, and I always liked flying with him.  The more expertise you have in the cockpit, the better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the two 747 carriers I worked for, an FE would sometimes transition to the FO seat, but that was relatively rare, and the costs were typically the individual's to bear.  Interestingly, when I retired in 1999, I had flown with an ex-military FE who years later became the chief pilot of the airline involved.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="6919" LastEditDate="2015-05-04T06:01:06.743" LastActivityDate="2015-05-04T06:01:06.743" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14545" PostTypeId="2" ParentId="14538" CreationDate="2015-05-04T07:41:35.563" Score="9" Body="&lt;p&gt;I found a  different number for $C_L$, please check your calculation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_L=\frac{2 m g}{\rho V^2 S}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;substitute: &#xA;$&#xA;m = 50000 \textrm{ kg}\\&#xA;g = 9.81 \textrm{ m}/\textrm{s}^2\\&#xA;V = 462 \textrm{ KTAS} = 237.67\textrm{ m/s}\\&#xA;S = 122.6 \textrm{ m}^2\\&#xA;\rho = 0.475 \textrm{ kg}/\textrm{m}^3&#xA;$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will give:&#xA;$C_L = 0.298$&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that this lift coefficient is for the total aircraft. It includes the lift of the wing, the fuselage lift and also the negative lift of the vertical stabilizer. There is also a small vertical component of thrust that is neglected.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now that we have an estimate of the lift coefficient, we can estimate the angle of attack. Normally the lift coefficient is assumed to vary linearly with the angle of attack:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_L = \frac{\textrm{d}C_L}{\textrm{d}\alpha}\cdot (\alpha-\alpha_0)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\alpha_0$ is the zero-lift angle of attack, the angle of attack at which the wing does not generate any lift. For symmetric airfoils, $\alpha_0 = 0$, for chambered airfoils $\alpha_0 &amp;lt; 0$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know what that angle is for the A320, it will be difficult to obtain. Let's assume for now it is -1.2 degrees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For infinite long wings in incompressible flow the lift slope $\frac{\textrm{d}C_L}{\textrm{d}\alpha}$ is $2\pi$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$(\alpha-\alpha_0) = \frac{C_L}{2\pi} =0.0474 \textrm{ rad} \approx 2.72^\circ$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would result in an angle of attack of $\alpha \approx 1.52^\circ$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the wing of the Airbus A320 is not infinitely long but has a span of about 30 meters (excluding the fuselage) we need to correct for that. The reason we need to correct for the finiteness of the wing is that the circulation will cause the local angle of attack of the wing to be lower than the free stream angle of attack. The effective angle of attack $\alpha_{eff} = \alpha - \alpha _i$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The induced angle of attack $\alpha_i$ is given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\alpha_i = \frac{C_L}{\pi AR} = \frac{C_LS}{\pi b^2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;substitute: &#xA;$   &#xA;S = 122.6 \textrm{ m}^2\\b = 30 \textrm{ m}&#xA;$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;gives $\alpha_i = 0.0129 \textrm{ rad} \approx 0.74^\circ$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding this to our earlier angle of attack results in:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ 1.52 + 0.74 = 2.26^\circ$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may not be very accurate as &lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) the zero-lift angle of attack may be very different, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) the lift slope may be flatter due to compressibility effects&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1467" LastEditDate="2015-05-04T11:08:44.693" LastActivityDate="2015-05-04T11:08:44.693" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="14546" PostTypeId="2" ParentId="14539" CreationDate="2015-05-04T09:35:29.197" Score="22" Body="&lt;p&gt;These are &lt;em&gt;wingtip vortices&lt;/em&gt;, which also appear in formula one, and &lt;a href=&quot;http://www.sportskeeda.com/f1/wingtip-vortices-in-formula-one-why-are-they-formed&quot;&gt;this article&lt;/a&gt; explains the reason quite nicely (including airplane pictures and going into the difference between them and contrails).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The significant paragraph:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After the formation of the vortex, the pressure inside it decreases significantly as compared to the ambient pressure. This results in a significant drop in dew point (which was already below the ambient temperature before the formation of the vortex) but along with it, there is an even greater drop in the vertex core temperature, which transforms the water vapour into water droplets and hence we are able to see the vortices trail coming out of the rear endplates.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2401" LastActivityDate="2015-05-04T09:35:29.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14547" PostTypeId="1" CreationDate="2015-05-04T15:14:10.903" Score="14" ViewCount="22776" Body="&lt;p&gt;I am aware that wind shear is the geostrophic wind between two pressure levels and am also aware of the catastrophic effect microbursts can have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If informed, can the crew avoid wind shear? And if not, how do they deal with it?&lt;/p&gt;&#xA;" OwnerUserId="8383" LastEditorUserId="65" LastEditDate="2015-05-04T15:30:33.660" LastActivityDate="2015-05-04T16:03:17.287" Title="How do pilots respond to wind shear?" Tags="&lt;weather&gt;&lt;pilot-technique&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14548" PostTypeId="1" AcceptedAnswerId="14551" CreationDate="2015-05-04T15:45:43.187" Score="3" ViewCount="942" Body="&lt;p&gt;Is it possible to calculate the lift of an aircraft knowing its speed (IAS,TAS and GS), its vertical speed, its altitude and its weight?&#xA;Because if we look at the force of an aircraft in flight: the lift is opposed to the weight and if the lift is greater than the weight, the aircraft climbs with a certain rate (vertical speed) proportional to the lift.&lt;/p&gt;&#xA;" OwnerUserId="8374" LastActivityDate="2015-08-29T19:17:36.640" Title="How to calculate the lift starting from the vertical speed?" Tags="&lt;lift&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14549" PostTypeId="2" ParentId="14547" CreationDate="2015-05-04T15:49:33.957" Score="15" Body="&lt;p&gt;When an aircraft experiences changing winds as it climbs or descends, this is technically &amp;quot;windshear&amp;quot; and it can have consequences (changes in airspeed and turbulence), but the much more dangerous phenomena is the microburst, and discussions of windshear avoidance and recovery are mostly concerned with that.&lt;/p&gt;&#xA;&lt;p&gt;There are some good tools available for avoidance: major airports typically have &lt;a href=&quot;http://en.wikipedia.org/wiki/Terminal_Doppler_Weather_Radar&quot; rel=&quot;noreferrer&quot;&gt;Doppler radars&lt;/a&gt; that are designed specifically to detect microbursts and significant windshear events, and tower controllers broadcast those warnings.  Airliners and other aircraft with modern radar systems have similar capabilities, looking ahead into their flightpath for the next few miles.&lt;/p&gt;&#xA;&lt;p&gt;Without those capabilities, windshear detection was essentially accomplished by comparing groundspeed (from an INS or GPS) with indicated airspeed, and noting any changes in that relationship.  So if your GS was 120 and your IAS was 100 (the difference due to combined effects of the wind plus the delta between True and Indicated Airspeed), then suddenly you had 130 knots GS and 95 knots IAS, you've suddenly picked up some tailwind, and if that trend continues, the loss in indicated airspeed could become catastrophic, and so an escape is necessary.&lt;/p&gt;&#xA;&lt;p&gt;On a more basic level, some cues are typically published that may indicate windshear on approach:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;± 15 knots indicated airspeed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;± 500 fpm vertical speed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;± 5 degrees pitch attitude&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;1 dot displacement from the glideslope&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;unusual thrust lever position for a significant period of time&lt;/p&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.convectivedigital.com/guide/757-767%20Study%20Guide.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;When you receive a warning from Tower or your onboard systems, aircraft that haven't started taking off (or are very early in the takeoff roll) stay on the ground, and aircraft on approach will discontinue the approach (go around).  Since the effects of a microburst are much more pronounced close to the ground, the difference between encountering the microburst at 3000' AGL instead of 500' AGL may be the difference between a bumpy ride instead of a truly dangerous event.  Also, if the microburst can be localized, either from radar or visually by observing &lt;a href=&quot;http://en.wikipedia.org/wiki/Virga&quot; rel=&quot;noreferrer&quot;&gt;virga&lt;/a&gt; or a storm cell, then turning away from it is often appropriate.&lt;/p&gt;&#xA;&lt;p&gt;What is also practiced (in the simulator!) is what is referred to as a windshear escape maneuver, which is the aircraft manufacturer's (and possibly, operator's) best guidance for your best chance of surviving a windshear encounter.  This would typically involve steps like advancing the power to the maximum available, retracting speedbrakes (if extended) to reduce drag, rolling wings level, and climbing as quickly as possible.  At least in Boeing aircraft, it is not advised to change the flap configuration because doing so would increase your stall speed, and it's also not advised to retract the landing gear, because even though this would reduce the drag, it would also make any contact with the ground far more damaging.  Each aircraft has its own procedure, but that's a general case.&lt;/p&gt;&#xA;&lt;p&gt;A couple of links:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf&quot; rel=&quot;noreferrer&quot;&gt;Excellent discussion from Airbus of windshear &amp;amp; dealing with it&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=4&amp;amp;LLID=32&amp;amp;LLTypeID=12&quot; rel=&quot;noreferrer&quot;&gt;FAA Discussion of Microbursts&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-04T16:03:17.287" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14550" PostTypeId="2" ParentId="14509" CreationDate="2015-05-04T16:21:39.830" Score="2" Body="&lt;p&gt;I think you are seeing a difference here in where the SFC is being reported. The engines on the Concorde are optimized for supersonic cruise, and SFC is reported there. The fighter is not just optimized for supersonic cruise, so you can't assume the SFC value is for cruise. The YJ93 never saw much use, and the only value I can find for SFC is the one included in the question, but this is &lt;a href=&quot;https://books.google.com/books?id=_5vA_5XK33sC&amp;amp;pg=PA528&amp;amp;lpg=PA528&quot; rel=&quot;nofollow&quot;&gt;probably not at cruise&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare the &lt;strong&gt;33.8&lt;/strong&gt; g/(kNs) for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593&quot; rel=&quot;nofollow&quot;&gt;Concorde engines&lt;/a&gt; to other similar engines, using only values for supersonic cruise. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption&quot; rel=&quot;nofollow&quot;&gt;J-58&lt;/a&gt; (SR-71) at Mach 3.2 was &lt;strong&gt;53.8&lt;/strong&gt; g/(kNs) (wet), and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Kolesov_RD-36&quot; rel=&quot;nofollow&quot;&gt;RD-36&lt;/a&gt; (Tu-144) at cruise was &lt;strong&gt;35&lt;/strong&gt; g/(kNs).&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-04T16:21:39.830" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14551" PostTypeId="2" ParentId="14548" CreationDate="2015-05-04T16:27:17.237" Score="4" Body="&lt;p&gt;Yes, it is, at least for small pitch angles and low thrust. Here is how:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L = m\cdot g\cdot n_z\cdot\cos\gamma$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If thrust or pitch attitude become significant, you need to modify $m\cdot g$ by the vertical thrust component. Then the answer must be no, because the thrust information is missing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L = \left(m\cdot g - T\cdot\sin(\Theta + \sigma)\right)\cdot n_z\cdot\cos\gamma$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L\:\:\:$  lift&lt;br&gt;&#xA;$m\:\:$ mass&lt;br&gt;&#xA;$g\:\:\:$ gravitational acceleration&lt;br&gt;&#xA;$n_z\:\:$ load factor (= 1 in horizontal, unaccelerated flight) &lt;br&gt;&#xA;$\gamma\:\:\:$ flight path angle, with $\gamma = asin\left(\frac{v_z}{v}\right)$&lt;br&gt;&#xA;$v_z\:\:$ vertical speed &lt;br&gt;&#xA;$v\:\:\:$ flight speed (TAS)&lt;br&gt;&#xA;$T\:\:$ Thrust&lt;br&gt;&#xA;$\Theta\:\:$ pitch angle (up is positive)&lt;br&gt;&#xA;$\sigma\:\:$ thrust angle relative to airframe's x axis&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the altitude is only needed if you use the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gravity_of_Earth#Altitude&quot; rel=&quot;nofollow noreferrer&quot;&gt;altitude-specific value of $g$&lt;/a&gt;. Using the standard value will give you a negligible error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note also that lift &gt; weight will result in an upward acceleration. In a quasi-stationary climb or sink the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb/12720#12720&quot;&gt;lift will be slightly smaller than the weight&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-08-29T19:17:36.640" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14552" PostTypeId="2" ParentId="14536" CreationDate="2015-05-04T16:40:43.540" Score="2" Body="&lt;p&gt;I'll answer your second question first that why pneumatic headphones were phased out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simple answer would be that a better technology was available, and affordable on commercial level. Questions like DVDs replacing CDs, or why 3.5&quot; floppy disks replacing their 5.25&quot; counterparts, DSLRs replacing SLRs are all on the same lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electric headsets have several advantages in terms of quality of audio, durability, lower cost of production and longevity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why pneumatic headphones, or as a matter any headphones, were used in an airplane relates to why &lt;a href=&quot;http://en.wikipedia.org/wiki/In-flight_entertainment&quot; rel=&quot;nofollow noreferrer&quot;&gt;in-flight entertainment&lt;/a&gt; was places in airplanes? By 1960s, in-flight entertainment was getting popular and airlines were using it as marketing tool. As this evolved, headphones (pneumatic at the time) jacks were added for each passenger so that if a passenger doesn't want to be &lt;em&gt;entertained&lt;/em&gt;, can choose to do so.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Though this is not directly related, this question &lt;a href=&quot;https://aviation.stackexchange.com/q/9201/65&quot;&gt;What was the inflight entertainment in the early seventies?&lt;/a&gt; has some excellent information about in-flight entertainment, which does talk about pneumatic headphones too.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-04T16:40:43.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14553" PostTypeId="2" ParentId="14536" CreationDate="2015-05-04T17:47:12.320" Score="16" Body="&lt;p&gt;Well, the rubber hoses themselves were used instead of traditional electromag transducer headphones for two main reasons; first, the hoses were much cheaper than a decent pair of traditional headphones at the time, and to an extent they're washable, so airlines could provide a pair for everyone at a much lower pricepoint than traditional headphones. Second, the hoses were more or less useless without the driving system aboard the aircraft, largely removing the incentive for passengers to walk off with them, again reducing costs of providing the system to passengers. The system was phased out in favor of simple 1/8&quot; stereo jacks at each seat in the '80s and '90s as portable audio became mainstream, and as airlines looked to dramatically slash costs in the face of deregulation beginning in 1978. Economies of scale meant that buying cheapo Walkman-style headphones in bulk became cheaper than maintaining the aging pneumatic systems, and the electric-based system was more reliable and had several advantages (such as volume control for each passenger, and if standard 1/8&quot; jacks were used, the ability for a savvy flyer to bring their own, nicer pair for use on the flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside, this pneumatic audio system is still used today for a very different purpose; newborn hearing screenings. A pair of flaps with a mild adhesive are stuck to baby's ears, then hoses lead back to a finely-calibrated audio system coupled to an EEG. Audio is played and the EEG is monitored to detect the response to the sound in baby's brain. The hose system is used because it allows the expensive, fine-tolerance part of the audio system to be reused from test to test, while the hoses themselves are disposable and (as hospital equipment goes) fairly inexpensive.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-04T18:01:21.167" LastActivityDate="2015-05-04T18:01:21.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14556" PostTypeId="2" ParentId="14539" CreationDate="2015-05-04T18:21:08.207" Score="18" Body="&lt;p&gt;As other answers state, the vapor trail from the edge of the wing (or from other sections of the wing in various configurations) is the most visible effect of the wingtip vortex, a phenomenon in aerodynamics of airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Succinctly put, along most of the wing, the air passing over the wing and the air passing under it are pretty cleanly separated by the wing, and when reintroduced, while there's significant turbulence (creating &quot;induced drag&quot;) there's typically very little rotational quality to it; a sheet of air over the top of the wing meets a sheet of air from the bottom, where it mixes and settles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, at the wingtip, there's a stark border between air that isn't being separated by the wing and air that is. The air that passes over the top of the wingtip is typically directed downward as it leaves the wing, similar to the rest of the wing, and at the wingtip this downward force, in addition to the pressure differential at the wingtip itself (the higher pressure under the wing seeks to equalize with the lower pressure above it by moving around the wingtip), induces a rotation in the air column behind the wingtip; clockwise on the left wing, counter-clock on the right:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UpzX6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UpzX6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinning air creates a volume of lower pressure in the center of the column, like the eye of a hurricane, and when air conditions are just right, this reduction in pressure in the center of the vortex can cause a contrail as the humidity in the air condenses into fog. The greater the force of lift produced by the wing, the more forceful and thus larger these vortices can be; wingtip vortices behind large commercial airliners can extend for miles behind the airliner, posing problems for smaller craft in their wake especially in airport traffic patterns. Smaller craft, especially fighter jets, can produce similar contrails in high-G maneuvers as the higher angle of attack of the wing produces a severe pressure differential just above the wingtips, increasing the vortex effect. Modern 4.5 and 5th-generation jets with stealth in mind are designed to avoid this as it's a visual cue to the jet's location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect can be even more pronounced at the edges of deployed flaps, closer to the aircraft fuselage; here the flaps are inducing even more of a downward force on the air, and there's a similar discontinuity between the corner of the flap and the relatively straight wing next to it. Flaps are also typically deployed at lower altitudes where the air's thicker, warmer and can hold more moisture, so the atmospheric conditions for producing a vapor trail are more easily met:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Eo6iV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eo6iV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-05T19:09:32.320" LastActivityDate="2015-08-05T19:09:32.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14557" PostTypeId="1" CreationDate="2015-05-04T18:28:58.647" Score="1" ViewCount="1465" Body="&lt;p&gt;So I know that &lt;a href=&quot;https://aviation.stackexchange.com/questions/3693/how-does-altitude-affect-the-speed-of-sound&quot;&gt;altitude affects the speed of sound&lt;/a&gt; because of temperature differentials in the atmosphere, but I am curious what else affects how we hear planes overhead?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a plane flies overhead, you dont hear a very constant filter at all frequency bands. It seems that lower frequencies are more consistent, where high frequencies seems to fade in and out, sounding much like a low pass filter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this the product of the temperature differentials between you and the plane changing as the plane moves, or are there other factors? Does moving air affect the sound in any way?&lt;/p&gt;&#xA;" OwnerUserId="8388" LastActivityDate="2015-05-04T19:38:52.210" Title="How does altitude affect sound?" Tags="&lt;altitude&gt;&lt;noise&gt;&lt;high-altitude&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-05-04T19:02:17.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="14558" PostTypeId="2" ParentId="14557" CreationDate="2015-05-04T18:32:47.257" Score="1" Body="&lt;p&gt;The answer to your question has a lot to do with how waves generated by a moving object propagate. You can see a full explanation &lt;a href=&quot;http://en.wikipedia.org/wiki/Doppler_effect&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; but the short answer is the &lt;strong&gt;Doppler Effect&lt;/strong&gt; which causes pitch to change as the object moves buy you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice &lt;a href=&quot;https://www.youtube.com/watch?v=z0EaoilzgGE&quot; rel=&quot;nofollow&quot;&gt;explanation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My knowledge is a bit rusty but basically you are talking about a mechanical wave propagating through a fluid (the atmosphere) which will absorb some of the energy (eventually all of it). I would also thing that as the speed of sound changes the frequency of the wave would change much like the changes light has when it crosses different mediums.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-04T19:38:52.210" LastActivityDate="2015-05-04T19:38:52.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14559" PostTypeId="2" ParentId="14508" CreationDate="2015-05-04T19:54:43.627" Score="10" Body="&lt;p&gt;There are indeed several approximations, depending on the shape of the wing. Generally, the lift curve slope is $2\pi$ only for a flat plate in inviscid 2D flow (with Kutta condition fulfilled). With thicker airfoils, the lift curve slope in 2D increases slightly. It also increases with Mach number proportional to the Prandtl-Glauert factor $\frac{1}{\sqrt{1-Ma^2}}$ and the Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to 3D flow: Once you move away from infinite aspect ratios, the lift curve slope drops. With very small aspect ratios $AR$ the lift curve slope becomes $c_{L\alpha} = \frac{\pi \cdot AR}{2}$. See the plot below for the ideal lift curve slope of an unswept wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KRknE.png&quot; alt=&quot;lift curve slope over AR&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that the red line is only valid for AR = 0! Then the lift curve slope increases up to $c_{L\alpha} = 2\cdot\pi$  for $AR = \infty$ (and zero airfoil thickness and no friction effect), as shown by the blue line. If you know your airfoil lift curve slope, modify the result from the plot above by the ratio between the airfoil lift curve slope and $2\pi$. Now your lift coefficient will become:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$c_L = c_{L\alpha_{3D}}\frac{c_{L\alpha_{2D}}}{2\pi}\cdot\alpha$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with your angle of attack $\alpha$ in radians.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an analytic approach you may use the formulas below, but stay away from the region close to Mach 1. If those (rather precise) approximations look too daunting, feel free to simplify them:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZNjfm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZNjfm.png&quot; alt=&quot;lift curve slope equations&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_{L\alpha} \:\:$ lift coefficient gradient over angle of attack&lt;br&gt;&#xA;    $c_{L\alpha\:ic} \:$ lift coefficient gradient over angle of attack in incompressible flow&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\nu \:\:\:\:\:$  the wing's dihedral angle&lt;br&gt;&#xA;    $\varphi_m \:\:$  sweep angle of wing at mid chord&lt;br&gt;&#xA;    $\varphi_{LE} \:$  sweep angle of wing at leading edge&lt;br&gt;&#xA;    $\lambda \:\:\:\:\:$  taper ratio (ratio of tip chord to root chord)&lt;br&gt;&#xA;    $(\frac{x}{l})_{d\:max} \:$  chordwise position of maximum airfoil thickness&lt;br&gt;&#xA;    $Ma \:\:$  Mach number&lt;br&gt;&#xA;&lt;P&gt;&#xA;Note that you do not need the planform efficiency (Oswald factor) $\epsilon$ for calculating lift curve slope. That only comes into play when you compute the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;induced drag&lt;/a&gt; of the wing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2017-01-03T16:52:33.587" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14560" PostTypeId="2" ParentId="82" CreationDate="2015-05-04T20:33:36.873" Score="5" Body="&lt;p&gt;The true north pole, aka the celestial north pole, is the point on the Earth's surface intersecting Earth's rotational axis on the northern hemisphere (and thus the axis around which all stars appear to rotate). Prior to the introduction of the Global Positioning System, there were no perfect indicators of true north. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two competing and often conflicting definitions of north have been used prior to the advent of GPS (and since). Magnetic north is the direction in line with the Earth's magnetic field, thought to be caused by the convective flows of liquid iron in the Earth's outer core, which causes a compass to point toward the magnetic north pole. An approximation of &quot;celestial north&quot; is in the direction of Polaris, which is a fairly bright star in the night sky and also the closest such star to Earth's rotational axis (and thus &quot;true north&quot;) for about the last 1500 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the two poles do not coincide; here's a Google Earth image showing true north in green and magnetic north in red:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KYgM8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, they're close, especially from the perspective of those of us in the New World, but if you were sailing off the west coast of the British Isles, you might see up to a ten-degree difference between your compass and Polaris, and that's significant over a distance of even a few hundred miles. Navigators have known of this difference, known as the &quot;magnetic declination&quot;, for centuries, and it was a secondary driving reason for the solution to the &quot;problem of longitude&quot; (how to determine, quickly and accurately, your current longitude; knowing this, in addition to being a key coordinate of your position at sea, also allows you to determine the necessary amount of &quot;declination&quot; from magnetic north to determine true north and thus the correct magnetic heading to your intended destination).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, Earth's magnetic pole changes over time; here's a map showing the changes in the surveyed position of the magnetic north pole through Nunavut, Canada over the past 130 years or so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/25TWh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the magnetic pole appears to be approaching true north, possibly due to gyroscopic stabilizations of the convective flows within earth's liquid inner layers. Again, for most of the U.S. the practical effects of observed shifts are minimal, but it has much more pronounced effect near the Prime Meridian which happens to be nearly perpendicular to the line between true and magnetic north. &lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-27T01:03:14.380" LastActivityDate="2015-05-27T01:03:14.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14561" PostTypeId="2" ParentId="9005" CreationDate="2015-05-04T21:17:22.447" Score="3" Body="&lt;p&gt;Nobody so far seems to have mentioned gust locks. These are physical blocking devices intended to prevent the movement of control surfaces. Some are placed directly on those control surfaces, others are placed in the cockpit on the control column. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6x9KK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary purpose of most such devices is not a theft-deterrent; they're typically used to prevent the control surfaces moving incidentally while the aircraft is parked (mainly due to high winds, hence &quot;gust&quot; lock), but some designs can be keyed to prevent their removal by someone other than a keyholder (again the primary intention is not theft prevention, but more a &quot;maintenance lockout&quot; preventing manipulation of control surfaces from the cockpit while a mechanic is working with moving parts), and such devices would be the equivalent of &quot;The Club&quot; for aircraft, preventing a would-be thief from being able to maneuver the aircraft even on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some locks are intended to stymie operation of the aircraft in any meaningful way with the lock installed (for instance, physically blocking access to the magnetos switch), but nothing's foolproof (fools are too inventive) and there have been several fatal crashes recorded where the pilot attempted to take off with a gust lock still installed and the resulting loss of control was unrecoverable.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-27T01:07:58.983" LastActivityDate="2015-05-27T01:07:58.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14562" PostTypeId="1" CreationDate="2015-05-04T22:14:40.910" Score="4" ViewCount="3664" Body="&lt;p&gt;I know that $c_{d}=0.03 + 0.095c_{l}^2$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the glide ratio?&lt;/p&gt;&#xA;" OwnerUserId="7169" LastEditorUserId="97" LastEditDate="2015-05-05T01:06:30.860" LastActivityDate="2018-03-18T11:56:33.363" Title="How to calculate the Glide Ratio from Drag &amp; Lift?" Tags="&lt;lift&gt;&lt;drag&gt;&lt;glide-ratio&gt;&lt;performance-calculation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14563" PostTypeId="2" ParentId="2376" CreationDate="2015-05-04T23:34:11.710" Score="4" Body="&lt;p&gt;The &quot;safety&quot; of an aircraft is a function of the entire aircraft, from concept to design to manufacturing and assembly, and also of the people who fly it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very old anecdote; in one of the very first &quot;evaluations&quot; performed on competing pre-production aircraft to determine the one an air service should buy, Manfred von Richthofen flew what would become the Fokker D.VII. He stated the plane was very unstable, especially in a dive. As a result, the fuselage was lengthened by one box section (about 2-3 feet). Only very minor modifications were made elsewhere. On flying the modified prototype, Richthofen said it was the best craft he'd ever flown, and on this recommendation the D.VII entered service and became so feared that the Armistice specifically ordered the surrender of all German D.VIIs to the Allied forces. So, just this one change to the airframe turned an underpowered, temperamental aircraft into the most successful fighter design of WWI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fast-forward 97 years or so, and not much has really changed regarding this basic tenet. What has changed is the inherent amount of complexity in the average aircraft. We think of something like a Piper Cub as being fairly simple, and compared to an F-15 or a 747, they are, but even relatively inexpensive modern hobbyist planes have avionics, radio systems etc that put the original J-3s to shame. More complexity means more that can go wrong, even when the complexity is specifically designed to lower pilot workload.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-05-04T23:34:11.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14564" PostTypeId="2" ParentId="14562" CreationDate="2015-05-05T02:32:35.290" Score="6" Body="&lt;p&gt;The glide ratio for a given angle of attack is the ratio of lift to drag. Both of these are proportional to the respective coefficients (with a proportionality constant of $\frac12\rho v^2A$), so the glide ratio is simply $c_{\mathrm L}/c_{\mathrm D}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practically, what you're looking for may be the &lt;em&gt;maximal&lt;/em&gt; glide ratio. Finding the global maximum of&#xA;$$\frac{c_{\mathrm L}}{c_{\mathrm D}} = \frac{c_{\mathrm L}}{0.03+0.095 c_{\mathrm L}^2} = \frac1{c_{\mathrm D}}\sqrt{\frac{c_{\mathrm D}-0.03}{0.095}}=\sqrt{\frac1{0.095}\frac1{c_{\mathrm D}}-\frac{0.03}{0.095}\Bigl(\frac1{c_{\mathrm D}}\Bigr)^2}$$ should be a simple matter of algebra -- for the last expression you don't even need calculus, just finding the apex of a parabola.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="1961" LastEditDate="2015-05-05T07:10:41.480" LastActivityDate="2015-05-05T07:10:41.480" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14565" PostTypeId="1" AcceptedAnswerId="14566" CreationDate="2015-05-05T06:11:07.257" Score="5" ViewCount="13696" Body="&lt;p&gt;I've noticed that larger Boeing aircrafts (such as the 777, 767, 747, etc) are equipped with inboard ailerons. What is their purpose and why hasn't Airbus incorporated them on the A330 or the A340?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HQJqC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-05T09:01:46.397" Title="What is the purpose of an inboard aileron?" Tags="&lt;flight-controls&gt;&lt;boeing&gt;&lt;airbus&gt;&lt;boeing-747&gt;&lt;ailerons&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2015-05-05T12:32:36.827" ContentLicense="CC BY-SA 3.0" />
  <row Id="14566" PostTypeId="2" ParentId="14565" CreationDate="2015-05-05T06:54:43.677" Score="7" Body="&lt;p&gt;As far as I know, the inboard ailerons are used for high speed maneuvering.&#xA;The rolling moment induced by the ailerons is linearly dependent with the distance to the center of gravity (e.g. the farther out, the stronger the moment, the harder the roll).&#xA;As the aileron is an aerodynamic surface, the force induces is equal to:&#xA;$$F_{aileron} = c_l(\alpha) \frac{1}{2} \rho V^2 S_{aileron} $$.&#xA;The moment induced is equal to this force, multiplied by the distance to the c.o.g.:&#xA;$$M_{aileron} = y_{aileron} \cdot c_l(\alpha) \frac{1}{2} \rho V^2 S_{aileron} $$&#xA;If you're flying in cruise , and you want to make a smooth turn, you need a relatively small $M_{aileron}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the $V^2$ term, is already very large. So we want to make the rest of the terms relatively small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We could do this with outboard ailerons: Use the outboard aileron with a large $y_{aileron}$, combined with a small $c_l(\alpha)$, usually the outboard $S_{aileron}$ is fixed by the low speed control requirements.&#xA;However, you can provide $M_{aileron}$ more accurate if you use the inboard ailerons (with a small $y _{aileron}$). The smaller distance makes the moment a bit smaller, and less susceptible to small deviations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the Airbus A330 &amp;amp; A340 use their spoilers to maneuver at high speeds. They simply extend their spoilers -which are usually also reasonably close to the c.o.g.- a tiny bit, this changes the lift distribution, also causing a rolling moment. I did not research this fact, so I'm not 100% sure this is the reason the A330 and A340 do not have inboard ailerons, but I do know some aircraft use this method for high speed maneuvering.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-05-05T09:01:46.397" LastActivityDate="2015-05-05T09:01:46.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14567" PostTypeId="1" AcceptedAnswerId="14568" CreationDate="2015-05-05T08:03:32.920" Score="17" ViewCount="43656" Body="&lt;p&gt;I have heard of the terms &lt;em&gt;slice&lt;/em&gt;, &lt;em&gt;segment&lt;/em&gt; and &lt;em&gt;leg&lt;/em&gt;. Since I am a newbie in travel industry, I would like to know and understand the basic differences between the three. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone please explain the three, using some kind of example?&lt;/p&gt;&#xA;" OwnerUserId="8395" LastEditorUserId="1467" LastEditDate="2018-08-17T09:00:07.947" LastActivityDate="2021-02-12T04:33:42.143" Title="What is the difference between slice, segment and leg?" Tags="&lt;terminology&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="14568" PostTypeId="2" ParentId="14567" CreationDate="2015-05-05T09:15:57.117" Score="11" Body="&lt;p&gt;I'm pretty sure those terms are not used consistently across all organisations in the air travel industry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not defined in an IATA glossary I looked at but I did find this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;Definition of Flight Segment&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;The International Air Transport Association (IATA), the international trade body for airlines around the world, defines a flight segment as the operation of a flight with a single flight designator between the point where passengers first board an aircraft and the passengers' final destination. A flight designator includes an airline code, which has two letters or a number and a letter in combination, and a flight number of up to four digits. A flight segment can include any number of stops where passengers board and deplane the same aircraft operated by a single airline.&lt;/p&gt;&#xA;  &#xA;  &lt;h2&gt;Comparison of Flights and Legs&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;A flight is defined by the IATA as the operation of one or more flight legs with the same flight designator. Unlike a flight segment, a flight may involve one or more aircraft. The IATA defines a leg as the operation of an aircraft from one scheduled departure station to its next scheduled arrival station. A flight segment can include one or more legs operated by a single aircraft with the same flight designator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;From &lt;a href=&quot;http://www.ehow.co.uk/info_8332815_flight-segments-air-travel.html&quot; rel=&quot;noreferrer&quot;&gt;eHow&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-05-05T09:15:57.117" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14569" PostTypeId="1" AcceptedAnswerId="14575" CreationDate="2015-05-05T09:33:22.210" Score="18" ViewCount="13924" Body="&lt;p&gt;Why do the main landing gears of aircraft like the A330, 777, 787, etc tilt up? This does not happen with the 767. Interestingly, for the 747, the inner landing gear does not tilt up while the outer landing gear (under the wing) does. Why does that happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WokD0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="62" LastEditDate="2015-05-05T14:45:28.713" LastActivityDate="2021-03-18T02:06:28.337" Title="Why do certain aircraft's landing gear tilt up?" Tags="&lt;boeing&gt;&lt;landing-gear&gt;&lt;airbus&gt;&lt;boeing-747&gt;&lt;boeing-777&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14570" PostTypeId="1" AcceptedAnswerId="14572" CreationDate="2015-05-05T09:39:58.427" Score="10" ViewCount="11180" Body="&lt;p&gt;I've been looking for a detailed explanation for how the transponder works and the importance of a squawk code. &lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-05T10:11:18.493" Title="What is the significance of a squawk code?" Tags="&lt;navigation&gt;&lt;transponder&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14571" PostTypeId="1" CreationDate="2015-05-05T09:57:35.193" Score="19" ViewCount="1409" Body="&lt;p&gt;How do test pilots figure out an aircraft's capabilities (service ceiling, cruising altitude, etc.)? Do they simply take the plane to its limits to get that information?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="62" LastEditDate="2015-05-05T14:44:24.210" LastActivityDate="2015-12-11T10:19:32.493" Title="How do test pilots determine an aircraft's capabilities?" Tags="&lt;flight-testing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14572" PostTypeId="2" ParentId="14570" CreationDate="2015-05-05T10:08:03.980" Score="10" Body="&lt;p&gt;The squawk code is assigned by Air Traffic Control to the aircraft and is used for radar identification purposes. It is a 4 digit octal number (each digit has a value in the range [0-7]).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight crew enters the assigned squawk code into the transponder control panel and the radar extracts the code using a Mode-A interrogation (or UF5 / UF21 interrogation in case of a Mode S radar/ transponder). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extracted squawk code can then be used to correlate the radar reply with an aircraft's flight plan. A number of squawk codes are reserved for generic purposes and emergencies. These codes are used in emergency, or when no flight plan correlation is needed. Some generic codes are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;1000 - Conspicuity code signalling the Flight Data Processing system to use Mode-S Aircraft ID for flight plan correlation. (Primarily in Europe)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;1200 - Visual Flight Rules standard squawk code (USA &amp;amp; Canada)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;2000 - Used when entering a Secondary Surveillance Area and no code has yet been assigned. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;7000 - Visual Flight Rules standard squawk code (ICAO, USA &amp;amp; Canada use&#xA;1200 instead)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;7500 - Unlawful interference / hijack (ICAO, worldwide)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;7600 - Radio communication lost (ICAO, worldwide)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;7700 - General emergency (ICAO, worldwide)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-05T10:11:18.493" LastActivityDate="2015-05-05T10:11:18.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14573" PostTypeId="2" ParentId="14570" CreationDate="2015-05-05T10:08:16.603" Score="3" Body="&lt;p&gt;It allows Secondary radar to identify each aircraft. The response ping from the aircraft contains the 12 bit squawk code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each plane is assigned a different squawk code as they enter an airspace and the software compares that to the flight plans filed and then can display the relevant information on the display.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly VFR without a flight plan you will squawk the general VFR code until asked to change it when entering controlled airspace. When leaving tghe controlled airspace you will be asked to &quot;squawk VFR&quot; again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can also be used to declare emergency by squawking 7700, 7600 or 7500 (for general emergency, radio loss and hijack resp.)&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-05-05T10:08:16.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14574" PostTypeId="2" ParentId="14571" CreationDate="2015-05-05T10:53:49.120" Score="27" Body="&lt;p&gt;&lt;strong&gt;Short:&lt;/strong&gt;  The pilot has a well-defined range of discretion within progressively increasing bounds very tightly set as part of a structured development program aimed at eliciting maximum information regarding actual versus theoretical flight envelope in all conceivable modes and situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Longer:&lt;/strong&gt; A test pilot's main task is to carry out a progressive program of tests aimed at investigating the correspondence between designed and actual capabilities, and identification of any unexpected variations from nominal which occur along the way. The designers know everything they consider the aircraft should do and shouldn't do and should be able to do long before it first flies. The job of the test pilots is to find out the places where the designers are wrong by carrying out an extremely well planned program while applying her or his skill to come back alive when the designers and/or manufacturers get it wrong. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot will usually have input into the process of deciding the rate which the program is carried out, how large progressive steps are and attempting to anticipate in advance what is likely to be viable or problematic. Their feedback along the way will help inform decisions about modifying program objectives or rate of implementation or lead to modification to the aircraft. A highly skilled test pilot is a member of a synergistic team and while program decisions are the responsibility of the 'project manager' (or equivalent) it is likely that what the pilot says and wants will be close to indistinguishable from what actually is done. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the actual program on a given occasion is not the pilot's responsibility and limits on what are attempted or implemented are well-defined in advance. The pilot will be given discretion in advance regarding ranges of parameters which may be investigated, e.g., closeness of initial approach to Mach 1, rate of ascent or g forces applicable in various modes*. And the safety of the aircraft first and the pilot second (in many cases) is left to the pilot's discretion BUT subject to substantial guidance, e.g., 'bringing the aircraft back intact' is often going to provide far more information when a problem occurs so a pilot may make every effort to do so in situations where an ejection may otherwise be preferred. A  pilot who ejects more than most may or may not be criticized for any given decision but is less likely to be given as many chances in the future to risk their life even more than before. However, a pilot who crashes fatally while trying to save an out of control situation will in the future only take part as the subject in training videos and in establishing &quot;see if you could have handled this one&quot; simulation scenarios. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Striking the right balance between these two 'modes' is what makes a great test pilot. But they still don't just get to go out and &quot;see what it can do&quot;. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A well judged ejection occasion - genuine.&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.rafjever.org/118sqnper002.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;From here&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;English Electric Lightning early testing.  Prior ejection would very likely have been justifiable but is unlikely to have been considered. The pilot (George Aird) survived with relatively minor fractures - in part caused by descending through the roof of a glasshouse :-). Pilot was on final for an emergency landing as a fire was attacking the rudder actuator. At 100 feet altitude and 10 seconds from touchdown, Murphy won, the actuator support burned through and the plane pitched nose down. Go!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rXdMA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rXdMA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glasshouse with pilot and ejector seat entry points (side by side) ringed in red. Canopy caused damage at far end. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1gsWj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1gsWj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Photographers are lucky to get one opportunity like this in a lifetime.&lt;br&gt;&#xA;I'm still waiting :-)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What do I know?: Layman. Engineer. Non pilot. Read too many test-pilot autobiographies. The ones you read tend to be from those who are good &lt;strong&gt;and&lt;/strong&gt; didn't die. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I was recently rererereading Roland Beaumont's &quot;Phoenix into Ashes&quot; - an  account from the leading test-pilot of many (most) of the early British jet aircraft. He recounted the loss of a test aircraft while pulling 9g (as I recall) in a situation which should have been inside the design envelope. The pilot died. The observer lived to provide 'human black box' functionality. It was established that fuel transfer protocols were not correctly followed, leading to over-stressing part of the airframe and thus fatal loss of control, i.e., &quot;just&quot; mishandling fuel tank sequencing may kill you. Nowadays computers will tend to stop this sort of error. But Murphy has many alternatives.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4371" LastEditorUserId="2719" LastEditDate="2015-12-11T10:19:32.493" LastActivityDate="2015-12-11T10:19:32.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14575" PostTypeId="2" ParentId="14569" CreationDate="2015-05-05T13:20:00.873" Score="6" Body="&lt;p&gt;Pulling mostly from the answers provided &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/24169/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; it seems that &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The torque produced by the straightening gear helps to flatten the plane out.&lt;/li&gt;&#xA;&lt;li&gt;The main gear tilt on the B747 also provides air/ground sensing. All four main gear bogeys tilt when the aircraft is airborne, so on touchdown any systems relying on air/ground logic can activate&lt;/li&gt;&#xA;&lt;li&gt;The gear is tilted to fit into the wheel well&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can check the link for the rest of the explanations. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2015-05-05T15:16:43.087" LastActivityDate="2015-05-05T15:16:43.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14576" PostTypeId="1" AcceptedAnswerId="14577" CreationDate="2015-05-05T13:31:53.523" Score="9" ViewCount="3326" Body="&lt;p&gt;The distance between aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/2806/how-much-is-the-minimum-safe-distance-between-two-planes-in-flight/2813&quot;&gt;must be larger&lt;/a&gt; than the minimum separation all the time and is therefore &lt;a href=&quot;https://aviation.stackexchange.com/questions/12346/at-what-distance-between-two-aircraft-will-the-air-traffic-controller-get-an-ala&quot;&gt;quite important&lt;/a&gt; for Air Traffic Control (ATC). As I need to calculate the distance between aircraft for my research, I'm wondering if there are any regulations (in Europe) about how exactly the distance is determined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How exactly does ATC determine the distance between two aircraft?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that they are working with latitudinal and longitudinal coordinates and probably the altitude to determine great circle distances. To get the coordinates, they could use either radar or the position which is communicated by the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The task to calculate the distance from coordinates is not that trivial as it may sound from the first impression. One method to calculate the distance is the &lt;a href=&quot;http://www.movable-type.co.uk/scripts/latlong.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;haversine formula&lt;/a&gt;. In all methods, the assumed earth radius is &lt;a href=&quot;http://rosettacode.org/wiki/Haversine_formula&quot; rel=&quot;nofollow noreferrer&quot;&gt;rather crucial&lt;/a&gt;. If the distance is calculated in that manner:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Which value is used as the earth radius? &lt;/li&gt;&#xA;&lt;li&gt;Are the different earth radii from the equator to the meridian regarded?&lt;/li&gt;&#xA;&lt;li&gt;Is the altitude of flights included in the calculation?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3859" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-12T14:59:33.107" Title="What method does ATC use to calculate distance between two aircraft?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;radar&gt;&lt;separation&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14577" PostTypeId="2" ParentId="14576" CreationDate="2015-05-05T14:09:59.220" Score="21" Body="&lt;p&gt;The things you mention would matter, if you wanted to know the distance to 6 or more significant digits. But ATC does not need that precision. They need to be able to tell whether it's 4 nmi (too close), 5 nmi (still sufficient, but getting in trouble) or 10 nmi (no worry, but should not be heading directly towards each other). That is &lt;em&gt;one&lt;/em&gt; significant digit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller does not use &lt;em&gt;any&lt;/em&gt; formula. They just look at the distance of the targets on the radar scope (which is drawn properly to scale). And possibly use the grid that is drawn over it or compares to the leader lines (indicating velocity) or history trail. The controller doesn't need precision, they need to look and see. And they are not getting any precision; on centre station (controller handling en-route traffic) the radar target blob is about a mile wide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until recently, aircraft did not broadcast position at all. Many still don't; not all aircraft are equipped with ADS-B. For those that don't, the interrogator may have precision similar to DME (~ 0.1 nmi) in range and a degree or two in angle. Not great precision either. The radar also has single rotating antena that takes couple of seconds to scan the whole circle, so the position of the aircraft is only updated once every few seconds. Jet airliner in cruise moves some 700 m in 3 s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On such radar, the scope most likely transforms directly from the angle and distance reported by the radar to the screen coordinates. Altitude was usually &lt;em&gt;not&lt;/em&gt; taken into account (so higher targets appear further than they really are!) in the older systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;New radars with ADS-B support (less busy areas don't need it) need to combine the radar data with coordinates reported by ADS-B, which are in WGS84, so WGS84 is usually used as intermediate format for the collected data. But shortcuts can still be taken in the software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know what which radar system manufacturer uses, but I work on navigations and we tested the precision. By assuming Earth is flat and the coordinate system is orthogonal and using simple Pythagorean formula, you can still get 3-4 significant digits (unless you are working around north or south pole) for points tens of miles apart, which is more than enough for the radar screen. So the system can simply multiply longitude and latitude with appropriate factors (that depend on latitude of the sector centre) and get sufficient precision.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-05-12T14:59:33.107" LastActivityDate="2015-05-12T14:59:33.107" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="14578" PostTypeId="2" ParentId="13350" CreationDate="2015-05-05T15:19:26.527" Score="3" Body="&lt;p&gt;An air carrier must also have &lt;strong&gt;OPSPEC C065, POWERBACK OPERATIONS WITH AIRPLANES&lt;/strong&gt; to do this.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;OPSPEC C065—POWERBACK OPERATIONS WITH AIRPLANES.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A. General. &lt;strong&gt;C065 authorizes the use of powerplant reversing systems&#xA;  for rearward taxi operations.&lt;/strong&gt; Before issuing C065, the principal&#xA;  operations inspector (POI) must determine whether the operator meets&#xA;  requirements discussed in &lt;strong&gt;AC 120-29&lt;/strong&gt;, Criteria for Approval of Category&#xA;  I and Category II Weather Minima for Approach, current edition.&#xA;  Airplane types’ make, model, and series (M/M/S) authorized for&#xA;  powerback operations must be listed in C065. Airports where powerback&#xA;  operations are authorized must also be listed. If the POI and/or&#xA;  operator determine that restrictions to powerback operations are&#xA;  required at certain gates or ramp areas, the restrictions must be &#xA;  described (adjacent to the airport name) in the “Restrictions and&#xA;  Limitations” column. OpSpecs worksheets provide a template for listing&#xA;  authorized airplanes, airports, and restrictions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;B. Policies and Procedures for Ground Personnel During Ground&#xA;  Operations. Title 14 CFR part 121, §§ 121.133 and 121.135, part 134, §&#xA;  134.23, and part 135, § 135.21, require certificate holders to prepare manuals setting forth procedures and policies that must be used by&#xA;  ground and maintenance personnel in conducting their ground&#xA;  operations. Sufficient procedures must be established to maintain an&#xA;  adequate level of passenger and company ground personnel safety during&#xA;  ramp operations. Procedures should emphasize safety during boarding&#xA;  and deplaning of passengers or cargo, specifically during times when&#xA;  an engine(s) may be running or a propeller(s) is turning during ground&#xA;  operations. Procedures should include, as a minimum, a means for&#xA;  defining no access areas around the propeller(s), as well as the&#xA;  landing gear and tugs, during push and ground marshaling operations.&#xA;  Policies should provide that an adequate number of ground personnel&#xA;  are assigned to ensure safety of company personnel and passengers.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;C. Pushback and Ground Marshaling. Procedures for pushback and ground&#xA;  marshaling activities should be clearly defined and should include&#xA;  safety precautions and signals, and should ensure adequate visibility&#xA;  of assigned personnel during the time of aircraft movement.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;D. Increased Awareness. FAA air carrier surveillance programs should&#xA;  emphasize increased awareness by inspectors and the strict need to&#xA;  follow safety procedures around turning propellers, in marshalling and&#xA;  pushback procedures, and/or other ground activities.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;E. Other References. Additional references can be found in National&#xA;  Transportation Safety Board (NTSB) Recommendations 91-297, 91-298, and&#xA;  93-146, and Air Carrier Operating Bulletin (ACOB) 8-94-2, Safety in&#xA;  Ground Operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-05-06T15:19:41.417" LastActivityDate="2015-05-06T15:19:41.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14579" PostTypeId="1" AcceptedAnswerId="14581" CreationDate="2015-05-05T15:38:05.797" Score="14" ViewCount="20754" Body="&lt;p&gt;On &lt;a href=&quot;https://aviation.stackexchange.com/questions/14570/what-is-the-significance-of-a-squawk-code&quot;&gt;What is the significance of a squawk code?&lt;/a&gt; @DeltaLima gave a fairly concise answer. In it he listed several 'standard' codes used for things like emergencies.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also in the list was Code 2000, for which he included the description:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Used when entering a Secondary Surveillance Area and no code has yet been assigned  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, if I'm in the US, under VFR (code 1200) and I enter a Secondary Surveillance Area, I automatically change to Code 2000? Why wouldn't I have already been given (a specific) designator?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-07T08:44:52.317" Title="What is Transponder Code 2000 actually used for?" Tags="&lt;faa-regulations&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14580" PostTypeId="2" ParentId="14579" CreationDate="2015-05-05T15:58:50.273" Score="2" Body="&lt;p&gt;The US &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;ATC procedures&lt;/a&gt; say that 2000 is to be used for departing IFR aircraft (section 5-2-6):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Code 2000&lt;/strong&gt;  to an aircraft which will climb to FL 240 or above or to an aircraft which will climb to FL 180 or above where the base of&#xA;  Class A airspace and the base of the operating sector are at FL 180,&#xA;  and for inter-facility handoff the receiving sector is also stratified&#xA;  at FL 180. The en route code must not be assigned until the aircraft&#xA;  is established in the high altitude sector.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It looks like the specific information you quoted from the other answer simply doesn't apply in the US. The term &quot;secondary surveillance radar area&quot; &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/PCG_4-03-14.pdf&quot; rel=&quot;nofollow&quot;&gt;isn't in the P/CG&lt;/a&gt; and Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Transponder_%28aeronautics%29#Transponder_codes&quot; rel=&quot;nofollow&quot;&gt;says&lt;/a&gt; that the use of 2000 in relation to SSR areas is for ICAO countries only:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The code to be squawked when entering a secondary surveillance radar&#xA;  (SSR) area from a non-SSR area used as Uncontrolled IFR flight squawk&#xA;  code (ICAO countries)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It does give this information for the US, though:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Non-discrete code assignments in accordance with FAA Order JO 7110.65,&#xA;  5-2 *Also for use in oceanic airspace, unless another code is assigned&#xA;  by ATC (USA)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Order it mentions is the ATC instructions. I have no idea about oceanic operations, so I can't comment on that part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for VFR, &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM_Basic_4-03-14.pdf&quot; rel=&quot;nofollow&quot;&gt;the AIM&lt;/a&gt; simply says that all VFR traffic must squawk 1200 unless otherwise instructed by ATC.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-05-05T16:08:34.763" LastActivityDate="2015-05-05T16:08:34.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14581" PostTypeId="2" ParentId="14579" CreationDate="2015-05-05T16:01:18.693" Score="12" Body="&lt;p&gt;The purpose of squawk code 2000 is to prevent aircraft entering a Secondary Surveillance Radar (SSR) area from transmitting a code that is the same as a discrete code assigned by ATC to an individual aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying in the USA under Visual Flight Rules (VFR), you will be assigned (implicitly) code 1200. Upon entering a SSR area you might get assigned another code, but often you will keep code 1200 if you are not near class C airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying Instrument Flight Rules (IFR) outside a SSR area (e.g. entry into the US from oceanic airspace), you will use code 2000. Upon radar contact you will then get assigned a discrete code. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/319229&quot; rel=&quot;noreferrer&quot;&gt;FAA Advisory circular 91-70A - (Oceanic and International Operations)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;2.  EXPANDED OCEANIC CHECKLIST.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;.......&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;g.&#xA;  After Oceanic Entry&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) &lt;strong&gt;Squawk 2000&lt;/strong&gt;.  Thirty minutes after oceanic en try, crews should&#xA;  Squawk 2000, if  applicable. There may be regional differences  such&#xA;  as Squawking 2100 in Bermuda’s airspace or  maintaining last assigned&#xA;  Squawk in the West Atlantic Route System (WATRS). Crews  transiting&#xA;  Reykjavik’s airspace must  maintain last assigned Squawk.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another use of code 2000 is on the airport: before power up you can select code 2000 to avoid code conflicts that could occur when you would maintain your code from a previous flight. It is standard practice in many airlines to select code 2000 after arrival at the gate. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-07T08:44:52.317" LastActivityDate="2015-05-07T08:44:52.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14582" PostTypeId="2" ParentId="14579" CreationDate="2015-05-05T18:19:18.140" Score="8" Body="&lt;p&gt;You'll often hear ATC (Oakland Center or Los Angeles Center) tell aircraft that are heading out over the Pacific something along the lines of &quot;UAL ###, radar services are terminated, squawk 2000, contact ARINC on HF frequencies&quot; when they hand off control to the oceanic ATC.  The 2000 code simply means that the aircraft IS being controlled, but NOT right now by any radar controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they kept whatever squawk they had leaving Oakland or LA center, then there would be the possibility of a conflict as they entered somebody else's radar coverage (Hawaii, Guam, Japan, etc).  So instead of sorting out what the aircraft that are no longer in radar contact are squawking, they simply give them all the standard 2000 code, and when the aircraft is back in radar contact with (whoever), then that controller assigns them a code that works with his center.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-05T18:19:18.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14583" PostTypeId="1" AcceptedAnswerId="14584" CreationDate="2015-05-05T23:04:34.617" Score="6" ViewCount="3731" Body="&lt;p&gt;As an Air Cadet, we go gliding very frequently. However, I've noticed something about the airport that we go to. The airport that we go to, &lt;a href=&quot;http://en.wikipedia.org/wiki/Markham_Airport&quot;&gt;Markham Airport&lt;/a&gt;, has a different airport code. &lt;strong&gt;CNU8&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, other airports, such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Buttonville_Municipal_Airport&quot;&gt;Toronto-Buttonville&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Billy_Bishop_Toronto_City_Airport&quot;&gt;Toronto-City-Centre&lt;/a&gt;, and &lt;a href=&quot;http://en.wikipedia.org/wiki/Toronto_Pearson_International_Airport&quot;&gt;Toronto-Pearson&lt;/a&gt; all have the following codes respectively: &lt;strong&gt;CYKZ&lt;/strong&gt;, &lt;strong&gt;CYTZ&lt;/strong&gt;, and &lt;strong&gt;CYYZ&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do the numbers in airport codes signify something? If they don't, why is there a mix of both letters and numbers?&lt;/p&gt;&#xA;" OwnerUserId="7670" LastActivityDate="2015-05-06T15:26:03.113" Title="What do numbers signify in airport codes?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14584" PostTypeId="2" ParentId="14583" CreationDate="2015-05-05T23:08:31.380" Score="9" Body="&lt;p&gt;The code for Markham Airport, &lt;strong&gt;CNU8&lt;/strong&gt;, is a Transport Canada identifier. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The codes for the other airports are &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code&quot;&gt;ICAO airport codes&lt;/a&gt;. ICAO airport codes always consist of 4 letters. Markham Airport does not have an ICAO airport code.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-05-05T23:08:31.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14585" PostTypeId="1" AcceptedAnswerId="14591" CreationDate="2015-05-05T23:47:38.853" Score="14" ViewCount="3433" Body="&lt;p&gt;This is a follow up to my previous question &lt;a href=&quot;https://aviation.stackexchange.com/questions/14583/what-do-numbers-signify-in-airport-codes&quot;&gt;&lt;em&gt;What do numbers signify in airport codes?&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that case, I was asking why my local airport (Markham Airport) had a number in its code (&lt;em&gt;CNU8&lt;/em&gt;). I later learned that the code was not &lt;em&gt;really&lt;/em&gt; a code, but a Transport Canada Identifier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This leads me to my question, &lt;em&gt;Why do some airports not have ICAO codes?&lt;/em&gt; At my local airport, there is plenty of glider activity, and a flight school is also located there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My main thoughts for the airport not having a code comes from the lack of an Air Traffic Control Tower. When declaring a landing, pilots have to do declare it on &lt;em&gt;Traffic&lt;/em&gt;, which doesn't have a controller. It looks something like this (based on memory, I'm not a pilot but I hope to be one):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Markham Traffic, Aircraft Papa Lima landing on the grass strip beside whatever runway&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Am I correct in assuming that airports without ICAO codes don't have codes because of the lack of a control tower? Or is there other reasons for this?&lt;/p&gt;&#xA;" OwnerUserId="7670" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-06T08:23:33.337" Title="Why do some airports not have ICAO codes?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;icao&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14586" PostTypeId="2" ParentId="14583" CreationDate="2015-05-05T23:50:54.400" Score="4" Body="&lt;p&gt;There are numerous coding schemes for airport identifiers... they're often broken down into 3 main categories. ICAO, IATA, and country of origin. Sometimes these are all the same, other times, each one is completely different from the other. Each of these schemes evolved for different purposes(or diverged from each other at various times, aka ICAO added a fourth character from the IATA code bank and then diverged from there).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ICAO - International air traffic&lt;/li&gt;&#xA;&lt;li&gt;IATA - Ticketing information for the airlines.&lt;/li&gt;&#xA;&lt;li&gt;Country of origin - A way to identify all the airports in a specific country.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For example, in the US, there are some 15,000 airports. Most are small grass strips or similar, but each often needs its own identifier. There aren't enough 3 letter or 4 letter only combinations, so they start adding numbers. 4V4, 20GE, etc. &lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-05-05T23:50:54.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14590" PostTypeId="2" ParentId="14509" CreationDate="2015-05-06T07:37:31.590" Score="23" Body="&lt;p&gt;You compare SFCs at different speeds. That is like comparing payloads for differently sized aircraft. SFC goes up with speed and, therefore, must be compared at the same speed. The work performed by an engine is thrust times distance, and higher speed means that the same thrust will perform more work per unit of time when the engine moves faster. The moving engine needs to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11949/how-is-combustion-flame-maintained-in-the-combustion-chamber-after-igniters-are/11964#11964&quot;&gt;slow down the airflow for combustion&lt;/a&gt; to take place, and then needs to accelerate the air by more than it has been slowed down to have positive thrust. Hence, SFC goes up in parallel with speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To have a meaningful comparison, we need to define efficiency. There are several, and two are of major importance for air-breathing aircraft engines: Thermal efficiency and propulsive efficiency.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Thermal efficiency&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This describes how efficiently the chemical energy in the fuel $Q$ is converted into an impulse change of the air flowing through the engine. Formulated using the mass flow per unit of time $\dot{m}$, the impulse is $\dot{m}\cdot\dfrac{\Delta v^2}{2}$. Using $v_{\infty}$ for the incoming air speed and $v_{\infty} + \Delta v$ for the exit flow speed, the thermal efficiency is $$\eta_{therm} = \frac{\dot{m}\cdot \left((v_{\infty} + \Delta v)^2 - v_{\infty}^2\right)}{2\cdot Q}$$&#xA;To achieve good efficiency at high speed, a high $\Delta v$ is helpful. This explains why efficiency drops more over speed for high-bypass ratio engines and especially propellers.&#xA;Since the thermal energy in fuel is the same for all engines in your question, because all run on kerosene, and we can assume a similar efficiency of combustion, we can neglect $Q$ in the comparison.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Propulsive efficiency&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This describes how well the conversion is performed. Using the same variables as above, propulsive efficiency is $$\eta_{prop} = \frac{v_{\infty}}{v_{\infty} + \frac{\Delta v}{2}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This equation explains the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/why-are-radial-engines-uncommon-on-commercial-aircraft/10037#10037&quot;&gt;better efficiency&lt;/a&gt; of high-bypass ratio engines and propellers at the same speed, because propulsive efficiency is proportional to the inverse of $\Delta v$.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Overall efficiency&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This is the product of thermal and propulsive efficiency, and the equation is $$\eta_{total} = \frac{T\cdot v_{\infty}}{Q}$$&#xA;where $T = \dot{m}\cdot\Delta v$ denotes the thrust. Conveniently, $\Delta v$ is eliminated in the product, allowing turbojet engines like the Olympus&amp;nbsp;593 to look much better in comparison to other engines.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Intake efficiency&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This answer would be incomplete without a look at the intake of the Concorde. At cruise, it would lift the pressure of the air at the compressor face by a factor of more than six over ambient by efficiently decelerating the flow. The compressor added a compression ratio of 12, so the pressure in the combustion chamber was 80 times higher than ambient. This high pressure makes the engine so efficient, but is also &lt;a href=&quot;https://aviation.stackexchange.com/questions/10002/why-is-the-combustor-volume-of-a-jet-engine-decided-by-altitude/10014#10014&quot;&gt;needed to maintain combustion&lt;/a&gt;. Remember, ambient pressure in 18&amp;nbsp;km is just 76 mbar, so the absolute pressure in the combustion chamber at cruise was only 6 bar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full answer would be like this: The combination of intake and Olympus&amp;nbsp;593 at Mach&amp;nbsp;2.02 had a very good total efficiency, and comparisons with other engines at static conditions are misleading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The comparison of results from a test stand on the ground would yield a very different picture, however.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-18T09:15:34.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14591" PostTypeId="2" ParentId="14585" CreationDate="2015-05-06T08:23:33.337" Score="6" Body="&lt;p&gt;There is plenty of information on the Internet on how &lt;a href=&quot;http://www.skygod.com/asstd/abc.html&quot;&gt;certain and specific identifiers came to life&lt;/a&gt;, however the codes are sometimes not directly assigned by ICAO, &lt;a href=&quot;http://airportguide.com/airport_ids_paper.php&quot;&gt;but by the member nations&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ICAO Document 7910 - Location Identifiers contains codes allocated by national governments, on behalf of ICAO, to airports, airfields and other facilities such as ATC and weather stations. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ultimately, it is the national CAA's or other authorities' decision whether to assign a code and get it validated through ICAO. The decision may be based on political, historical or other reasons, there is no minimum requirements for airports to receive an ICAO code.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Am I correct in assuming that airports without ICAO codes don't have codes because of the lack of a control tower? Or is there other reasons for this?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The availability of a control tower is not a requirement for ICAO codes, even small uncontrolled fields with grass strips can have an ICAO code, example: &lt;a href=&quot;https://skyvector.com/airport/EDKW/Werdohl-Kuntrop-Airport&quot;&gt;EDKW / Werdohl-Küntrop&lt;/a&gt; &lt;a href=&quot;http://www.lsv-sauerland.de/index.php?option=com_content&amp;amp;view=article&amp;amp;id=2&amp;amp;Itemid=103&quot;&gt;(600m grass / uncontrolled / PPR)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-05-06T08:23:33.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14592" PostTypeId="2" ParentId="14430" CreationDate="2015-05-06T14:01:03.557" Score="0" Body="&lt;p&gt;If all you're looking for is calculations of ETE, ETA, headings, fuel burn, and other such items you can make use of the FAA's &lt;a href=&quot;https://duats.com/&quot; rel=&quot;nofollow&quot;&gt;DUATS&lt;/a&gt; platform. &lt;a href=&quot;http://skyvector.com/&quot; rel=&quot;nofollow&quot;&gt;Skyvector&lt;/a&gt; has some basic capability in this area as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll have to chase down the actual aircraft performance data to input into the software if you want realistic estimates, but the internet is awash with information manuals and operating handbooks for the more widespread families of light aircraft. Google is your friend for this one. As for numbers between waypoints, the simple and lazy, but often sufficient, solution is to simply interpolate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial solutions exist as well such as &lt;a href=&quot;https://www.foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;ForeFlight&lt;/a&gt; and AOPA's &lt;a href=&quot;http://www.aopa.org/Flight-Planning/FlyQ&quot; rel=&quot;nofollow&quot;&gt;FlyQ&lt;/a&gt;, but I doubt they would add anything of substantial value for your particular needs.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-05-06T14:01:03.557" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14593" PostTypeId="2" ParentId="14583" CreationDate="2015-05-06T15:26:03.113" Score="5" Body="&lt;p&gt;The FAA's rules are in their &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/atpubs/lid/lidhme.htm&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Location Identifiers&lt;/em&gt;&lt;/a&gt; paper, which explains how the numbers are used, at least for the US. It also mentions Transport Canada, by the way, and I guess that Canada uses similar rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are specific requirements for an airport to qualify for a three-letter identifier:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. Three-letter identifiers are assigned as radio call signs to&#xA;  aeronautical navigation aids; to airports with a manned air traffic&#xA;  control facility or navigational aid within airport boundary; to&#xA;  airports that receive scheduled route air carrier or military airlift&#xA;  service, and to airports designated by the U.S. Customs Service as&#xA;  Airports of Entry. Some of these identifiers are assigned to certain&#xA;  staffed aviation weather reporting stations or for airports&#xA;  commissioning Automated Weather Observation Systems, level III&#xA;  (AWOS-III) or higher that have paved runways 5,000 ft or longer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That three-letter code is then prefixed with 'K' for the continental US, to give the four-letter international code:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An international location indicator is a four-letter code used in&#xA;  international telecommunications. The location indicator for airports&#xA;  in the contiguous United States is the three-letter identifier&#xA;  preceded by &quot;K&quot;. For other non-contiguous United States airports, the&#xA;  following two letter prefix will be used:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Alaska - PA, PF, PO, PP&lt;br&gt;&#xA;  Hawaii - PH&lt;br&gt;&#xA;  Puerto Rico - TJ&lt;br&gt;&#xA;  Virgin Islands - TI&lt;br&gt;&#xA;  (See ICAO Document 7910 for listings.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The one-letter two-number format is usually used for &lt;em&gt;public&lt;/em&gt; airports that don't qualify for a three-letter identifier:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;d. Most one-letter, two-number identifiers are assigned to public-use&#xA;  landing facilities within the United States and its jurisdictions,&#xA;  which do not meet the requirements for identifiers in the three-letter&#xA;  series. Some of these identifiers are also assigned to aviation&#xA;  weather reporting stations.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;One-letter, two-number identifiers are keyed by the alphabetical letter. The letter may appear in the first, middle or last position in&#xA;  the combination of three characters. When the letter signifies an Air&#xA;  Traffic Control Center's area, the assignment will not change if the&#xA;  Center's boundaries are realigned.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The two-letter, two-number format is usually used for &lt;em&gt;private&lt;/em&gt; airports that don't qualify for a three-letter identifier:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;e. Two-letter, two-number identifiers are assigned to private-use&#xA;  landing facilities in the United States and its jurisdictions which do&#xA;  not meet the requirements for three-character assignments. They are&#xA;  keyed by the two-letter Post Office or supplemental abbreviation&#xA;  (listed below) of the state with which they are associated. The&#xA;  two-letter code appears in the first two, middle, or last two&#xA;  positions of the four-character code.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-06T15:26:03.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14595" PostTypeId="1" CreationDate="2015-05-07T10:58:23.793" Score="8" ViewCount="3545" Body="&lt;p&gt;The aerodynamic model cited in &lt;a href=&quot;http://groups.csail.mit.edu/robotics-center/public_papers/Hoburg09a.pdf&quot; rel=&quot;noreferrer&quot;&gt;this paper (pdf)&lt;/a&gt; as &quot;flat plate theory&quot; was a good first-order approximation of the aerodynamics of a perching glider. I immediately saw the similarity with the &lt;a href=&quot;http://www.aerospaceweb.org/design/waverider/theory.shtml&quot; rel=&quot;noreferrer&quot;&gt;Newtonian theory&lt;/a&gt; that works well in hypersonics, but it is only a similarity, not the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Around the internet I found these other two articles: &lt;a href=&quot;http://www.nrel.gov/docs/fy05osti/36900.pdf&quot; rel=&quot;noreferrer&quot;&gt;(1)&lt;/a&gt; and &lt;a href=&quot;http://www.researchgate.net/profile/W_Timmer/publication/254887563_Aerodynamic_characteristics_of_wind_turbine_blade_airfoils_at_high_angles-of-attack/links/542189650cf203f155c6e103.pdf&quot; rel=&quot;noreferrer&quot;&gt;(2)&lt;/a&gt;, which make reference to this flat plate theory in the context of wind turbines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Where does this flat plate theory come from? &lt;/li&gt;&#xA;&lt;li&gt;In what textbook or article or other bibliographic reference can I find its derivation?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://arc.aiaa.org/doi/pdf/10.2514/6.2007-6372&quot; rel=&quot;noreferrer&quot;&gt;Here is another article&lt;/a&gt; that cites this flat plate theory, now in the context of aircraft flight dynamics. This one makes reference to &lt;a href=&quot;http://www.nrel.gov/docs/fy05osti/36900.pdf&quot; rel=&quot;noreferrer&quot;&gt;(1)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://onlinelibrary.wiley.com/doi/10.1002/we.122/pdf&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; is yet another one in the context of wind turbines. &lt;/p&gt;&#xA;" OwnerUserId="8413" LastEditorUserId="1696" LastEditDate="2015-05-08T14:39:50.917" LastActivityDate="2019-05-13T17:39:21.313" Title="Where does the flat plate theory in this paper come from?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14596" PostTypeId="1" AcceptedAnswerId="14604" CreationDate="2015-05-07T12:18:02.367" Score="3" ViewCount="2412" Body="&lt;p&gt;I am interested in obtaining raw ceilometer data, to test some cloud/aerosol layer identification algorithms.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this type of data freely available or will I need to ask for it directly from the airport?&lt;/li&gt;&#xA;&lt;li&gt;Do airports keep an archive of raw data or simply of cloud heights as determined by manufacturers algorithm and provided in METAR reports?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8414" LastEditorUserId="8414" LastEditDate="2015-05-08T09:34:41.550" LastActivityDate="2020-09-24T07:24:03.317" Title="Is there a database of airport ceilometer raw data?" Tags="&lt;weather&gt;&lt;datasets&gt;&lt;measurement&gt;&lt;visibility&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14597" PostTypeId="1" AcceptedAnswerId="14870" CreationDate="2015-05-07T12:36:22.847" Score="12" ViewCount="3490" Body="&lt;p&gt;Let's say for the sake of the question, the plane is an &lt;strong&gt;787 Dreamliner&lt;/strong&gt; and the engine is the &lt;strong&gt;General Electric GEnx-1B64&lt;/strong&gt; (that according to &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GEnx&quot;&gt;Wikipedia&lt;/a&gt; can produce a maximum thrust of &lt;strong&gt;284 kN&lt;/strong&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In comparison to the &quot;regular forward&quot; thrust that a jet engine can generate, how much thrust can we apply to this engine in the reverse mode?&lt;/li&gt;&#xA;&lt;li&gt;Can we apply full power in the reverse mode?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="1696" LastEditDate="2015-05-19T20:33:59.600" LastActivityDate="2015-12-07T22:30:50.640" Title="How much thrust can the thrust reversers create?" Tags="&lt;jet-engine&gt;&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14598" PostTypeId="1" AcceptedAnswerId="14602" CreationDate="2015-05-07T12:45:30.137" Score="10" ViewCount="2295" Body="&lt;p&gt;I'm a Chemistry student preparing an in-class lab demonstration that involves the combustion properties of jet fuel used in typical US based airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is all jet fuel the same, or do I need to consider specific blends when designing my experiment? Is there a standard chemical formula for jet fuel? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And for bonus points, are there any critical handling considerations?&lt;/p&gt;&#xA;" OwnerUserId="8416" LastEditorUserId="65" LastEditDate="2015-05-07T15:58:45.643" LastActivityDate="2015-05-08T13:42:10.947" Title="Is all jet fuel the same?" Tags="&lt;safety&gt;&lt;fuel&gt;&lt;fire&gt;" AnswerCount="3" CommentCount="13" FavoriteCount="1" ClosedDate="2015-05-08T09:08:28.090" ContentLicense="CC BY-SA 3.0" />
  <row Id="14601" PostTypeId="2" ParentId="1439" CreationDate="2015-05-07T13:29:17.830" Score="4" Body="&lt;p&gt;Quite a few years back, about 28 to be exact I worked on Mirage III service for the RAAF and one of my jobs was to fit the ejection seats after major airframe servicing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally they were fitted with Martin Baker OM6 and these seats were zero-90 classification. They were powered by cartridges, basically a big multi stage canon that shot you out of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means they were able to be used at zero altitude and 90 knots forward speed, the speed was purely to have enough air flow to open the chute fully but mostly to help with the removal of the canopy by blowing it backwards. The canopy jettison would unlock the canopy and lift the front into the airstream, the forward motion would do the rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later we made a modification to the seats to make them into zero/zero capability and this included fitting a rocket pack under the seat that would launch the seat to a safe height enough for the parachute to open normally. &#xA;In both cases the seats were capable of going through the canopy but normally the canopy would eject first except in the zero zero situation where the seat would go through the canopy.&lt;/p&gt;&#xA;" OwnerUserId="8418" LastEditorUserId="3386" LastEditDate="2015-05-07T14:16:14.233" LastActivityDate="2015-05-07T14:16:14.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14602" PostTypeId="2" ParentId="14598" CreationDate="2015-05-07T13:31:33.230" Score="15" Body="&lt;p&gt;The fuel used by civilian airlines, fueled in the USA, is &lt;a href=&quot;http://en.wikipedia.org/wiki/Jet_fuel&quot;&gt;Jet A&lt;/a&gt;. To acquire some, go to a nearby airport which can handle operations by Turboprop or Turbofan aircraft. Some of the smaller airports, only supporting piston aircraft operations, may not be able to help you, but anything which can handle a Lear Jet should be able to supply you with examples of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no specific chemical formula for this. It is a mixture of a variety of compounds. And no, you can't isolate just one particular compound and use it as a representative sample. There are reasons for the various additives, and all of them will have SOME effect on the burn characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try not to breathe the fumes, before or after combustion. Do not operate any kind of radio transmitter (including a cellphone) within 50 feet of the vapors of it (when the fuel is exposed to air, before or during combustion). Make sure that whatever vessel you're going to burn it in is metal (plastic doesn't respond well to burning petrochemicals :-) and make sure there is good electrical conductivity between the vessel and the ground. Have a large, CO2- or Halon-based (NOT water or dry chemical) fire extinguisher nearby.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I was refueling F-16s in the Air Force:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;no radio transmitters (walkie talkies, at the time) were allowed with 50 feet of refueling operation&lt;/li&gt;&#xA;&lt;li&gt;the aircraft and the refueling vehicle BOTH had to be grounded and connected to each other BEFORE connecting the refueling line&lt;/li&gt;&#xA;&lt;li&gt;no refueling ops were permitted if there was lightning within 5 miles&lt;/li&gt;&#xA;&lt;li&gt;no refuelings ops were permitted without a 50-pound halon-based fire extinguisher and a dedicated person (fire guard) to man it&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This should give you some idea of proper safety around this stuff.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="65" LastEditDate="2015-05-07T14:05:05.297" LastActivityDate="2015-05-07T14:05:05.297" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14603" PostTypeId="2" ParentId="14598" CreationDate="2015-05-07T14:32:10.987" Score="9" Body="&lt;p&gt;If you have any intention of doing this, and &lt;strong&gt;&lt;em&gt;I DON'T ADVISE YOU LIGHT A POOL OF JET FUEL ON FIRE... EVER...&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you insist take a look at this &lt;a href=&quot;http://www.hess.com/docs/us-safety-data-sheets/jet-fuel-jp-5.pdf&quot;&gt;Material Safety Data Sheet&lt;/a&gt; which outlines all the safety and emergency aspects of Jet-A as well as other important info on it (provided by Hess).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One extremely important thing you must note is that the flash point (point where the fuel becomes vaporous and can ignite) is only &lt;strong&gt;100°F&lt;/strong&gt; this is not very high and a temperature that can be achieved in common settings. So make sure to transport it safely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/&quot;&gt;Airport Facility Directory&lt;/a&gt; will tell you what fuel every airport has and will list it as either Jet-A1 or Jet-A. You may also see 100LL or 110LL; this is not what you want, this is for piston engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;TALK TO A FIREMAN BEFORE DOING THIS!!&lt;/em&gt;&lt;/strong&gt; I am still advising that you avoid this in the first place but if you insist please consult with a fireman (potentially from an airport) on the proper things you will need to put out a fire and how and where the best place to do this is. You should assume you will need to be outdoors.      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2015-05-07T16:44:43.903" LastActivityDate="2015-05-07T16:44:43.903" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14604" PostTypeId="2" ParentId="14596" CreationDate="2015-05-07T14:55:12.533" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.ogimet.com/metars.phtml.en&quot; rel=&quot;nofollow noreferrer&quot;&gt;OGIMET&lt;/a&gt; looks like it goes back to 2005. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My favorite weather site &lt;a href=&quot;http://www.wunderground.com/history/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weather Underground&lt;/a&gt; has historical data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like you need to plug in dates one at a time but there are plenty of ways to skim a page and im sure you can ask them for a data dump if you know what you need. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="62" LastEditDate="2018-03-02T21:47:04.830" LastActivityDate="2018-03-02T21:47:04.830" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14605" PostTypeId="1" AcceptedAnswerId="14620" CreationDate="2015-05-07T15:00:43.830" Score="19" ViewCount="13483" Body="&lt;p&gt;What are the critical steps a pilot follows to perform an auto-rotation landing?&lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="2171" LastEditDate="2015-05-08T14:45:41.217" LastActivityDate="2017-04-25T18:59:33.120" Title="How does a helicopter pilot execute an auto-rotation landing?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14607" PostTypeId="2" ParentId="14595" CreationDate="2015-05-07T19:40:39.317" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ludwig_Prandtl&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ludwig Prandtl&lt;/a&gt;'s &lt;a href=&quot;http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/liftline/liftline.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;lifting line theory&lt;/a&gt; produces a &lt;a href=&quot;http://en.wikipedia.org/wiki/Taylor_series&quot; rel=&quot;nofollow noreferrer&quot;&gt;Taylor series&lt;/a&gt; as the result of the lift equation, and in almost all books this has been simplified just to the first term of the series, which then was even robbed of its sinus function to simplify it even further by using a &lt;a href=&quot;http://en.wikipedia.org/wiki/Small-angle_approximation&quot; rel=&quot;nofollow noreferrer&quot;&gt;small-angle approximation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you will find in books today is something like: &lt;span class=&quot;math-container&quot;&gt;$$c_L = c_{L\alpha}\cdot\alpha$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$c_l$&lt;/span&gt; is the lift coefficient, &lt;span class=&quot;math-container&quot;&gt;$c_{L\alpha}$&lt;/span&gt; is the lift curve slope and &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; is the angle of attack in radians.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the author should at least mention (but I think most are ignorant of this detail) is that a more precise version would be: &lt;span class=&quot;math-container&quot;&gt;$$c_L = c_{L\alpha}\cdot\sin\alpha$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now the books should tell you that there are more members in the solution to the lift equation; the one above is only the first one which dominates the result for small values of &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt;. But they don't. That is OK when the aircraft moves only through the small angle of attack region of attached flow, but for the perching motion you need to look at bigger angles, so the small-angle solution will produce noticeable errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lifting-line theory assumes inviscid flow and does not know about flow separation. Perched flight of birds would be impossible without the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14236/is-there-always-a-stall-if-you-exceed-a-specific-angle-of-attack/14257#14257&quot;&gt;high angle of attack&lt;/a&gt;s which produce flow separation and makes use of &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620#3620&quot;&gt;instationary effects&lt;/a&gt; which delay separation. All this is not covered by lifting line theory, but nevertheless it produces quite useable results. I guess, however, that the equation in the paper was found empirically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift equation cited in the paper is a consequence of observing forces in a 360° polar, one where the airfoil is rotated through full 360° instead of the narrow range between maybe -8° and +12° where flow is attached and lift forces vary linearly with the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot below is from &lt;a href=&quot;https://de.scribd.com/doc/26107035/Hoerner-Fluid-Dynamic-Lift-1985&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hoerner's book &quot;Fluid Dynamic Lift&quot; (Scribd)&lt;/a&gt; and shows the results of several measurements over 180°. Apart from the spikes around 15° and 175°, the forces correspond well with &lt;span class=&quot;math-container&quot;&gt;$c_L = x\cdot\sin\alpha\cdot\cos\alpha$&lt;/span&gt;, where &lt;span class=&quot;math-container&quot;&gt;$c_L$&lt;/span&gt; is the lift coefficient, &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; denotes the angle of attack and &lt;span class=&quot;math-container&quot;&gt;$x$&lt;/span&gt; is a proportionality factor (the paper postulates &lt;span class=&quot;math-container&quot;&gt;$x$&lt;/span&gt; = 2).&#xA;&lt;img src=&quot;https://i.stack.imgur.com/pkSpz.png&quot; alt=&quot;Plot of &lt;span class=&quot;math-container&quot;&gt;$c_L$&lt;/span&gt; over 180° angle of attack from Hörner&amp;#39;s book&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flat plate has no leading edge radius and, consequently, no &lt;a href=&quot;http://jeb.biologists.org/content/206/23/4191/F5.expansion.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;leading edge suction&lt;/a&gt;, which would be responsible for the aforementioned spikes. Therefore, the simple trigonometric approximation will fit the data quite well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the flat plate and Newtonian theories assume the aerodynamic force to be orthogonal to the plane of the wing or plate, and when you take the portion of that force which is orthogonal to the direction of movement, which is how lift is defined, you get above trigonometric equation. This is simple geometry and shows no deeper insight into fluid mechanics.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-05-13T17:39:21.313" LastActivityDate="2019-05-13T17:39:21.313" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="14608" PostTypeId="2" ParentId="11476" CreationDate="2015-05-07T20:32:50.050" Score="9" Body="&lt;p&gt;This is actually somewhat common on GA aircraft. The Beech Bonanza and Piper Saratoga, Meridian, Matrix, and Seneca have &quot;Club Seating&quot; (as well as I'm sure other 6 place planes I don't know about)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As seen here in this Saratoga&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://images.globalair.com/ganimages/generic/Singles/Piper/Saratoga%20SP/PA-32R-301/Interior/81_PiperSaratoga_N43WW_i2_i.jpg&quot; alt=&quot;Saratoga&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if this is a safety thing or a design matter but it does fall under your question &lt;em&gt;Is there any plane with such a configuration?&lt;/em&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2017-05-23T03:56:02.067" LastActivityDate="2017-05-23T03:56:02.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14609" PostTypeId="1" AcceptedAnswerId="14610" CreationDate="2015-05-07T21:33:48.203" Score="14" ViewCount="1104" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/14602/354&quot;&gt;This answer&lt;/a&gt; mentions that &lt;strong&gt;before refueling equipment is connected&lt;/strong&gt; the F-16 and the refueling vehicle must be connected to each other. This does not seem to be the case for &lt;a href=&quot;https://www.youtube.com/watch?v=sL5MxCwkLJQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;in-air refueling&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why is the above-mentioned restriction not practiced for in-air refueling?&lt;/strong&gt; Is there no chance of electrical voltage potential between two flying aircraft? Are the fuel lines purged before connecting in flight? Are fuel explosions not a big problem while the craft are flying? Are in-air safety considerations lower than on-ground safety considerations?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-07T21:49:14.983" Title="How are in-air refuelling craft grounded to each other?" Tags="&lt;military&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14610" PostTypeId="2" ParentId="14609" CreationDate="2015-05-07T21:49:14.983" Score="7" Body="&lt;p&gt;The metal of the tanker's boom (or drogue) contacts the metal of the receiver's receptacle (or probe) first, and that contact is maintained, so that would serve to ground the two aircraft to each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a good question, but I've never heard of any fuel explosions due to static buildup during air-to-air refueling, so evidently the systems in place alleviate the risks.  Aerial refueling is pretty routine these days, so in relative terms it would seem to be fairly safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Purging the fuel lines is a relative term; you could remove the liquid fuel from the lines, but you'd still have vapors, and those are more flammable than the liquid jet fuel itself.  Maybe somebody who flew (or flies) tankers can discuss how far down the boom the fuel goes BEFORE everything is connected and they start pumping; as a receiver I just remember that the fuel flowed into the manifold and then into the tanks.  We didn't do anything special to clear the manifold or fuel lines on our end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There ARE some inherent risks when refueling between two aircraft flying in close formation that are accepted (i.e. the risk level is okay for the military mission, but nobody does it for commercial airliners), but I don't think this is one of them.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-07T21:49:14.983" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14611" PostTypeId="2" ParentId="14598" CreationDate="2015-05-07T21:49:56.150" Score="7" Body="&lt;p&gt;As the other answers have said, you really really don't want to try this experiment yourself, and especially not indoors, but in fact jet fuel is surprisingly difficult to ignite, unless you atomize it or vaporize it first. The safety hazard comes from the fact that it is even more difficult to extinguish a jet fuel fire than to light it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard safety demonstration by our works fire department includes dropping a lighted cigarette into a bucketful of fuel, which has no effect whatever. &lt;a href=&quot;https://www.youtube.com/watch?v=7nL10C7FSbE&quot; rel=&quot;nofollow&quot;&gt;The start of this video&lt;/a&gt; is a more dangerous version of that test - and to repeat, don't try this yourself!&lt;/p&gt;&#xA;" OwnerUserId="8206" LastEditorUserId="65" LastEditDate="2015-05-08T13:42:10.947" LastActivityDate="2015-05-08T13:42:10.947" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14612" PostTypeId="1" CreationDate="2015-05-07T23:06:26.797" Score="1" ViewCount="1585" Body="&lt;p&gt;I was wondering if any general aviation manufacturers currently produce center stick control aircraft.  (Not including LSA, Sailplanes, Helicopters). I'm asking about four+ place aircraft other than the diamond da40.  &lt;/p&gt;&#xA;" OwnerUserId="8422" LastEditorUserId="8424" LastEditDate="2015-05-08T20:47:48.757" LastActivityDate="2016-03-21T15:31:46.143" Title="Companies that currently manufacture aircraft with center stick controls?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-05-08T07:18:51.340" ContentLicense="CC BY-SA 3.0" />
  <row Id="14614" PostTypeId="1" AcceptedAnswerId="14616" CreationDate="2015-05-07T23:44:25.693" Score="18" ViewCount="3368" Body="&lt;p&gt;It really bothers me that we can't find planes that weigh tons with black boxes (AFAIK) technology that's almost obsolete, on the other hand shark tags (AFAIK) work great for long time and we can monitor shark movement, depth, temperature, etc., all the time. So, why?&lt;/p&gt;&#xA;" OwnerUserId="2156" LastEditorUserId="22726" LastEditDate="2019-04-27T03:43:32.383" LastActivityDate="2019-04-27T04:05:03.367" Title="What makes flight recorders harder to find than tagged sharks?" Tags="&lt;aircraft-design&gt;&lt;gnss&gt;&lt;search-and-rescue&gt;&lt;flight-recorders&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14615" PostTypeId="2" ParentId="14614" CreationDate="2015-05-07T23:55:28.870" Score="12" Body="&lt;p&gt;Shark tags work by only sending the logged data when the shark resurfaces. Between those it just stores the data in memory until it can send it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sending underwater takes a lot of power otherwise.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-05-07T23:55:28.870" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14616" PostTypeId="2" ParentId="14614" CreationDate="2015-05-08T00:42:59.273" Score="45" Body="&lt;p&gt;They're different usage cases, and have to be engineered differently. Three major points:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A shark tag doesn't have to survive a &lt;a href=&quot;http://www.abc.net.au/news/2014-03-26/black-box-flight-recorders/5343456&quot; rel=&quot;noreferrer&quot;&gt;500mph impact (&lt;em&gt;#7 on the list&lt;/em&gt;)&lt;/a&gt; with the ground, and a flight recorder has to be able to do so. It adds a lot of padding and weight, and limits the kind of battery that can be used.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sharks also don't dive to a depth much greater than &lt;a href=&quot;http://en.wikipedia.org/wiki/Shark&quot; rel=&quot;noreferrer&quot;&gt;3000 feet on most occasions&lt;/a&gt;. A planes flight recorder is designed to survive to a much lower depth, under much larger amounts of pressure. Not to mention being designed to survive &lt;a href=&quot;http://www.npr.org/blogs/thetwo-way/2014/03/11/289189214/what-would-it-take-to-destroy-a-black-box&quot; rel=&quot;noreferrer&quot;&gt;all sorts of other things&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Another point regarding depth, it is much harder to search for a signal at a depth of 15,000 ft, than it is even at a depth of 5000 ft. &lt;a href=&quot;http://cdn.intechopen.com/pdfs-wm/45030.pdf&quot; rel=&quot;noreferrer&quot;&gt;This article&lt;/a&gt; shows how big of a difference you get between even 20 meters and hundreds of meters (not thousands), it gives a good idea of what I mean.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If a shark tag fails, nobody cares. If you tag 100 sharks and 30 of the tags survive, you still have some pretty good data. But if one airplane crashes and its black box fails, it's considered unacceptable. They are required to survive 100% of the time.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;All of these differences combined mean that black boxes are manufactured to much higher standards, and as a result they are bulkier, have different sorts of radios and require much more battery life (to support the larger systems) than a shark tag. All this conspires with the difficulty of getting a receiver deep into the ocean to make finding FDRs/CVRs really difficult.&lt;/p&gt;&#xA;&lt;p&gt;That's not to say they couldn't design one that is much better, it just becomes extremely expensive (as all things are on airplanes). And you have to determine if these edge cases (like flight MH370) are worth making an airplane a few million dollars more expensive (between R&amp;amp;D and certification, the later being quite expensive).&lt;/p&gt;&#xA;&lt;p&gt;I think the theory was they should be able to find any one of these within a month, and that may take some rethinking (maybe 3 months, or a year perhaps?) But they'll never be as successful as shark tags just because the requirements to be able to find one at that depth 100% of the time are quite different from the needs of a shark tag.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-08T22:15:00.017" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14617" PostTypeId="2" ParentId="14480" CreationDate="2015-05-08T01:29:09.447" Score="3" Body="&lt;p&gt;COST like most things that could be added to light aircraft and are not because it is not cost effective to do so.  Especially given that most light aircraft are based on 50-60 year old designs.   The Cessna 172 entered service in the late 1950's.   They would have to do a complete redesign of the aircraft which would cost millions to develop and certify.  The finished aircraft would be very expensive and people may not be willing to pay 700,000+ for a standard performance 4 seat light aircraft.   &lt;/p&gt;&#xA;" OwnerUserId="8424" LastActivityDate="2015-05-08T01:29:09.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14618" PostTypeId="2" ParentId="14612" CreationDate="2015-05-08T01:35:00.063" Score="1" Body="&lt;p&gt;Some of the lancair airplanes have it but those are kit built so Im not sure if you can count them as true production planes. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Vans aircraft &lt;/li&gt;&#xA;&lt;li&gt;Most Variants of the Piper Cub like planes that are still made &lt;/li&gt;&#xA;&lt;li&gt;Extra Aircraft&lt;/li&gt;&#xA;&lt;li&gt;Pipistril Aircraft&lt;/li&gt;&#xA;&lt;li&gt;Czech Sport (formally Piper Sport)  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Its worth noting that Cessna did recently have a run trying to make the &quot;Sky Catcher&quot; which was quickly discontinued but center stick none the less. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of light sport airplane and aerobatic planes tend to have center sticks. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-08T01:35:00.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14619" PostTypeId="2" ParentId="11476" CreationDate="2015-05-08T06:31:46.510" Score="10" Body="&lt;p&gt;It seems that backwarding seat make passenger feel not good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some airlines offer backward seat porducts in business and first class&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;United &lt;a href=&quot;http://www.seatguru.com/airlines/United_Airlines/United_Airlines_Boeing_747-400_B.php&quot; rel=&quot;noreferrer&quot;&gt;B747&lt;/a&gt; &amp;amp; &lt;a href=&quot;http://www.seatguru.com/airlines/United_Airlines/United_Airlines_Boeing_777-200_3_New.php&quot; rel=&quot;noreferrer&quot;&gt;B777&lt;/a&gt; Business class&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/muCUi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Etihad &lt;a href=&quot;http://www.seatguru.com/airlines/Etihad_Airways/Etihad_Airways_Airbus_A380.php&quot; rel=&quot;noreferrer&quot;&gt;A380&lt;/a&gt; business and first class &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VyR8C.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Morover, &lt;a href=&quot;http://www.seatguru.com/airlines/British_Airways/fleetinfo.php&quot; rel=&quot;noreferrer&quot;&gt;All(4) types of widebodies&lt;/a&gt; in BA do offer Business backward seats , its whole subsidiary Openskies also offer business backward seats &lt;a href=&quot;http://www.seatguru.com/airlines/OpenSkies/information.php&quot; rel=&quot;noreferrer&quot;&gt;in their b757&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xekGA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/XRNIv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-05-08T07:25:30.053" LastActivityDate="2015-05-08T07:25:30.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14620" PostTypeId="2" ParentId="14605" CreationDate="2015-05-08T07:58:58.593" Score="30" Body="&lt;p&gt;I am going to assume that by &amp;quot;critical&amp;quot;, you mean survivable.  I will also assume that the engine failure occurs at a height which will kill you.&lt;/p&gt;&#xA;&lt;p&gt;It's not so much critical steps, it's critical outcomes.  The single most critical outcome is to preserve, or regain, rotor RPM.  What steps are needed to do this will depend on what the aircraft is doing when the engine quits and, to a lesser extent, the type of the helicopter.  I will generalise for an &amp;quot;average&amp;quot; helicopter in straight and level flight.&lt;/p&gt;&#xA;&lt;p&gt;The immediate action that is drilled into everyone from the very earliest hours as a student is to lower the collective.  Doing this has three effects.  It removes the positive pitch from the blades which removes most of the drag, it aligns the rotor thrust vector with the axis of rotor rotation therefore not using rotor energy for anything except lift and it causes a clutch to disengage the rotor from the engine allowing it to freewheel.  From this point onwards, you are heading back towards earth.&lt;/p&gt;&#xA;&lt;p&gt;The second immediate action at the same time as lowering the collective (assuming forward flight) is to pull back on the cyclic to flare.  This loads the disc which causes it to &amp;quot;cone&amp;quot; upwards which reduces the disc diameter.  Therefore, the centre of gravity of the disc moves inwards and due to conservation of angular momentum, the rotor RPM increases.  For quite complex reasons, the nose of the helicopter will also pitch down when the collective is lowered so pulling back counters that tendency.&lt;/p&gt;&#xA;&lt;p&gt;The third immediate action is to push in the pedal on the opposite side to the rotation of the blades. If the blades rotate counter clockwise (to the left as the pilot sees it) you push in right pedal to reduce the thrust which is produced by the tail rotor which is no longer countering the yaw caused by the drag from the powered rotor.  This is less critical than the first two and although it can be dangerous and get you into an uncomfortable attitude, it is usually possible to recover from not pushing the pedal in immediately.  If you've got rotor RPM, then you can sort it out.&lt;/p&gt;&#xA;&lt;p&gt;Now you have successfully entered autorotation.  From here, fly more or less normally to the next critical point which is about 50' off the ground.&lt;/p&gt;&#xA;&lt;p&gt;What you've done is to ensure that the rotor has flying RPM and that you are managing energy by trading potential energy (height) for kinetic energy (rotor RPM).  The conversion is done by the airflow which now comes from under the disc and &amp;quot;drives&amp;quot; the rotor to maintain RPM.  The pitch is neutral, or maybe even negative but, the relative airflow is now &lt;strong&gt;upwards&lt;/strong&gt; through the disc and therefore, the blades have a positive angle of attack and generate some lift.  This stops the helicopter from falling.  There is some drag generated as a consequence of generating that lift, but it is easily overcome by the power which is now driving the rotor from that upward airflow.&lt;/p&gt;&#xA;&lt;p&gt;As long as you are descending, that conversion will happen and your RPM will be maintained.  The controls are rigged such that with the collective fully down, RPM will remain in the normal range.  Sometimes you have to tweak it a little with small amounts of collective, flares and turns but in general, you just fly towards your landing spot.  The allowed RPM range is greater in autorotation.  For example (and from memory), the R22 has a range of 97-103% in normal flight and 90-110% in autorotation.&lt;/p&gt;&#xA;&lt;p&gt;You are now descending with a high rate of descent and usually, significant forward speed.  You need to reduce both of those to get to a safe arrival. To do this, there are three more critical steps.&lt;/p&gt;&#xA;&lt;p&gt;Starting at about 50 feet (depending on lots of factors but let's stick with the average helicopter which entered autorotation from straight and level with significant altitude), you flare the aircraft by pulling back on the cyclic.  This will immediately begin to slow the aircraft.  It will also begin to increase RPM (you are now converting speed into rotor kinetic energy).&lt;/p&gt;&#xA;&lt;p&gt;At the same time, you increase collective to reduce the rate of descent by increasing the lift generated.  This will rapidly increase the drag, but now the energy needed to maintain the RPM is coming from the flare which is converting speed into RPM.  You also need to put in pedal to stop the aircraft from yawing as the drag increases on the rotor.&lt;/p&gt;&#xA;&lt;p&gt;Providing you get the entry right and your flare reduces the speed and rate of descent to something survivable, then you will walk away.  You might wreck the helicopter and break some bones, but arrive at 10 feet with only 20 knots and 150 feet per minute rate and you'll get away with it.&lt;/p&gt;&#xA;&lt;p&gt;If you are well trained and in practice, then you will land safely and smoothly with no damage to  machine or people.&lt;/p&gt;&#xA;&lt;p&gt;In summary, critical steps:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Entry.  Lever down, cyclic back, pedal in.&lt;/p&gt;&#xA;&lt;p&gt;Arrival.  Cyclic back, lever up, pedal in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-04-25T18:59:33.120" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14622" PostTypeId="2" ParentId="11582" CreationDate="2015-05-08T11:13:34.307" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Would the rudder be able to compensate the thrust imbalance? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It depends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to translate those regulations into practical examples is to look at the certification of the A330 and A340-300, which have approximately the same amount of total thrust, the difference being the engine configuration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Takeoff performance requirements are predicated on 1-engine out for both configurations. Hence you'll notice that the minimum climb gradient requirement means that the 4-engine loses less thrust, hence is capable of a higher takeoff weight; around   30-40T more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two engine out comes into play during the landing config, where VMCL2, two engine out minimum control speed in the landing config, is much higher than VMCL1; two engine out 340 has approximately the same amount of thrust as a one engine out 330, but the thrust line produces a greater moment on the 340. Incidentally these speeds don't change with weight and depend on handling qualities and directional control at the most unfavorable CG position, which is the AFT limit. VMCL2 is around 160 knots, which is well above normal landing speed, so at some point during the approach when landing is assured, the pilot will elect to reduce below the VMCL2 to normal landing speed. It will not be possible to select full thrust without losing directional control in this regime of flight, however the benefits of landing at lower speed offset this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to the takeoff case with two engines inoperative, although VMCL is not specifically defined for takeoff config and regulations don't specifically cover this scenario, at higher takeoff weights minimum control speed becomes less of an issue compared to VS1G and overall climb performance. While at lighter weights, it maybe possible to reduce thrust to maintain control if performance permits.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastEditorUserId="8030" LastEditDate="2015-05-08T13:06:28.923" LastActivityDate="2015-05-08T13:06:28.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14623" PostTypeId="1" CreationDate="2015-05-07T11:31:51.020" Score="6" ViewCount="6754" Body="&lt;p&gt;In a generic fixed-wing aircraft like a Cessna, what is the function of the tail section, i.e. the rudder and elevators?&lt;/p&gt;&#xA;" OwnerUserId="8447" OwnerDisplayName="aeroaks" LastEditorUserId="62" LastEditDate="2015-05-08T16:49:37.320" LastActivityDate="2015-07-31T18:00:44.013" Title="What is the function of the tail section on a fixed-wing aircraft?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="0" ClosedDate="2015-07-31T23:24:27.337" ContentLicense="CC BY-SA 3.0" />
  <row Id="14624" PostTypeId="1" CreationDate="2015-05-08T17:23:13.117" Score="4" ViewCount="2304" Body="&lt;p&gt;When should we use CAT II or III during landing in bad weather? What we have in our country the standard shows 800m and RVR of 550 m for the ILS, which category procedure should be used if the visibility below or above?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand nothing tells us if it is CAT II or CAT III inside the charts except at the large airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And regarding the DH during the CAT III is it always 50 RA ?&lt;/p&gt;&#xA;" OwnerUserId="8431" LastEditorUserId="1696" LastEditDate="2015-05-08T17:32:33.720" LastActivityDate="2018-12-21T07:06:43.103" Title="How do you choose CAT II vs. CATIII ILS?" Tags="&lt;landing&gt;&lt;weather&gt;&lt;instrument-flight-rules&gt;&lt;ils&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14625" PostTypeId="2" ParentId="14623" CreationDate="2015-05-08T18:57:03.313" Score="5" Body="&lt;p&gt;First off lets be clear that a tail section does the same thing on small aircraft that it does on large aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second off lets be clear that a tail section is not necessary for flight and there are planes like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop Grumman B2&lt;/a&gt; that dont have a tail section they are affectionally called &quot;Flying Wings&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is that the rudder (vertical part) controls yaw and the elevator (horizontal part) controls pitch. A plane is capable of movement and similarly adjustment in all 3 dimensional axes. But lets dig in a bit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Elevator:&lt;/strong&gt; This is usually located in the back but by no means has to be. &lt;a href=&quot;http://en.wikipedia.org/wiki/Burt_Rutan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Burt Rutan&lt;/a&gt; has implemented many designs that have forward mounted elevators. As to functionality they essentially allow you to alter the pitch of the plane which in turn alters the angle of attack of the wing which furthermore has a direct effect on the lift generated by the wing. In a simple world we could say that when you pitch up you climb and when you pitch down you descend. The reality is that the engines thrust plays a large factor in this. For example if you are flying at a level attitude and increase thrust your will increase speed (and the speed of air over the wing) which will generate greater lift and cause the plane to elevate with out a pitch increase (you will have to apply some force to keep the plane level though). The elevator provides a way to easily alter the pitch of the plane (and angle of attack) so you can climb when you want. Generally speaking you will also add power for the climb. For a more lengthy explanation check out the &lt;a href=&quot;http://en.wikipedia.org/wiki/Elevator_%28aeronautics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipeidea article&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Rudder:&lt;/strong&gt; The rudder is mainly to control the left-right yaw of the aircraft. In a single engine prop plane this can be used to help overcome the left turning tendencies created by uneven force of a spinning prop (&lt;a href=&quot;http://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow noreferrer&quot;&gt;P-Factor&lt;/a&gt;). In a more general case the rudder is often used to correct yaw when a heavy crosswind is present on landing. It is also used in flight to ensure your turns neither skid or slip (stay coordinated) remember &lt;a href=&quot;http://en.wikipedia.org/wiki/Turn_and_slip_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Step On The Ball&quot;&lt;/a&gt;. For more reading check out &lt;a href=&quot;http://en.wikipedia.org/wiki/Rudder#Aircraft_rudders&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture shows the axes of movement pretty well. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/HPKpX.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-08T19:12:07.493" LastActivityDate="2015-05-08T19:12:07.493" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14626" PostTypeId="2" ParentId="14624" CreationDate="2015-05-08T19:19:51.967" Score="7" Body="&lt;p&gt;If both are available for the runway you're using, it's often easiest just to set up the Cat III, because you have the least risk that way of a random cloud between the Cat II DA and the Cat III DA interfering with your approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there may be reasons to prefer the slightly higher mins of the Cat II, and those are typically specific to your equipment and your procedures.  Perhaps crosswinds, either steady or gusts, make the Cat II more desirable, or if your equipment has a limitation on &quot;XYZ must be operative for Cat III approaches&quot; and that happens to be deferred on MEL for you, then the Cat II is the better (only) option.  But generally, if both are available, setting up for the Cat III is usually preferred unless some specific factor drives you to the Cat II.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Separate from this, some runways only &lt;strong&gt;have&lt;/strong&gt; a Cat II approach and not a Cat III available.  This is typically driven by runway lighting differences, although other equipment may drive this as well (specifically, a backup Glideslope transmitter, IIRC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As much as I hesitate to answer &quot;always,&quot; I can't think of any Cat IIIA DA that's other than 50' RA, and I can't think of a reason it would be, since you're over the runway itself by that point.  Cat II DA's can be slightly above or below 100' RA since the terrain you're over when you reach 100' above the TDZ (on glideslope) may be slightly above or below the runway elevation, but that's a Cat II thing, not a Cat IIIA deal.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2018-12-21T07:06:43.103" LastActivityDate="2018-12-21T07:06:43.103" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="14627" PostTypeId="2" ParentId="14221" CreationDate="2015-05-08T19:58:41.140" Score="6" Body="&lt;p&gt;It would have to be completely in compliance with &lt;a href=&quot;https://www.faa.gov/regulations_policies/airworthiness_directives/&quot; rel=&quot;nofollow&quot;&gt;ADs&lt;/a&gt; and if you are going over 25sm from your base airport or doing any true charter work you need a Part 135 &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_operator&amp;#39;s_certificate&quot; rel=&quot;nofollow&quot;&gt;AOC&lt;/a&gt; and have to be in compliance with the Part 135 regs. You can get a single pilot operator certificate for one pilot and one plane.  You also would need to comply with Part 136 which regulates air tours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things you would have to do are brief passengers on safety features of the aircraft and provide life jackets (if flying over water).  You also need permission to fly over national parks.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;136.37 A commercial air tour operator may not conduct commercial air tour&#xA;  operations over a national park or tribal land except&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) In accordance with this section;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) In accordance with conditions and limitations prescribed for that operator by the Administrator; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) In accordance with any applicable air tour management plan for the park or tribal lands&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(b) Application for operating authority. Before commencing commercial air tour operations over a national park or tribal lands, a commercial air tour operator shall apply to the Administrator for authority to conduct the operations over the park or tribal land&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are approved you may be subject to a limited number of tours over the area.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are keeping it under Part 91, with in 25sm, you will need a letter of authorization from your FSDO. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Regulations for Part 91&lt;br&gt;&#xA;  §91.147   Passenger carrying flights for compensation or hire.&lt;br&gt;&#xA;  Each Operator conducting passenger-carrying flights for compensation or hire must meet the following requirements unless all flights are conducted under §91.146.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) For the purposes of this section and for drug and alcohol testing, Operator means any person conducting nonstop passenger-carrying flights in an airplane or helicopter for compensation or hire in accordance with §§119.1(e)(2), 135.1(a)(5), or 121.1(d), of this chapter that begin and end at the same airport and are conducted within a 25-statute mile radius of that airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) An Operator must comply with the safety provisions of Part 136, subpart A of this chapter, and apply for and receive a Letter of Authorization from the Flight Standards District Office nearest to its principal place of business.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each application for a Letter of Authorization must include the following information:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(1) Name of Operator, agent, and any d/b/a (doing-business-as) under which that Operator does business;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(2) Principal business address and mailing address;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(3) Principal place of business (if different from business address);&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(4) Name of person responsible for management of the business;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(5) Name of person responsible for aircraft maintenance;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(6) Type of aircraft, registration number(s), and make/model/series; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;(7) An Antidrug and Alcohol Misuse Prevention Program registration.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;(d) The Operator must register and implement its drug and alcohol testing programs in accordance with Part 120 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;(e) The Operator must comply with the provisions of the Letter of Authorization received.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would assume that the aircraft would have to comply with Part 91 requirements.  If in doubt ask your local FSDO. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;THIS IS NOT LEGAL ADVICE. I AM NOT A LAWYER NOR DO I WORK FOR THE FAA. THIS IS A PILOT’S INTERPRETATION OF THE FARs.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="8424" LastEditorUserId="2143" LastEditDate="2016-02-20T16:50:57.083" LastActivityDate="2016-02-20T16:50:57.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14628" PostTypeId="2" ParentId="14623" CreationDate="2015-05-08T20:27:28.760" Score="3" Body="&lt;p&gt;The function of the tail section of a conventional fixed wing aircraft is to provide stability. It also holds two important control surfaces; the rudder and the elevator. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vertical tailplane, also called vertical stabilizer helps the aircraft's nose facing into the direction of the relative air flow. If the aircraft is in a side-slip, which means the nose of the aircraft is pointing left or right of the direction of the relative airflow, the vertical tailplane will create an aerodynamic moment forcing the nose into the wind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bKXxt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vertical tailplane also contains the rudder. The rudder is a control surface which controls the aircraft's yaw moment. The pilot controls the rudder by using the rudder pedals. This allows the pilot to correct disturbing pitch moments which might come from the propeller or to bring the aircraft intentionally into a sideslip, for example for a crosswind landing. During turns the rudder is used to ensure the turn is coordinated (keep the sum of the weight and centrifugal force pointing down the vertical axis of the aircraft) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal tailplane, or horizontal stabilizer is for longitudinal stability. Usually it provides the horizontal stabilizer gives and aerodynamics down force, thereby keeping the nose up. That may sound counter intuitive, but is essential for the stability of conventional aircraft. When the airspeed increases the aerodynamic forces increase as well. Due to the increase of the lift force on the main wing combined with an increase in down force on the horizontal stabilizer the nose of the aircraft will be forced upward. This causes the aircraft then to trade kinetic energy for potential energy and the speed will reduce again. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal stabilizer also contains the elevator. This control surface allows the pilot to control the pitch moment of the aircraft. Aircraft can be trimmed such that they maintain a constant pitch angle at constant speed without the need to constantly give elevator inputs. This trimming is done by either a small trim tab on the elevator, but in other aircraft the angle of whole horizontal stabilizer can be changed to trim the aircraft. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-08T20:46:49.710" LastActivityDate="2015-05-08T20:46:49.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14629" PostTypeId="1" AcceptedAnswerId="17168" CreationDate="2015-05-09T03:46:01.487" Score="19" ViewCount="92079" Body="&lt;p&gt;In terms of aircraft equipment, approach minimums, procedural differences, and anything else relevant, how do the 3 types of a Cat III ILS differ from one another?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="1467" LastEditDate="2015-07-23T07:05:41.390" LastActivityDate="2021-05-01T14:25:46.390" Title="What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?" Tags="&lt;approach&gt;&lt;icao&gt;&lt;ils&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14630" PostTypeId="2" ParentId="14605" CreationDate="2015-05-09T04:28:44.963" Score="5" Body="&lt;p&gt;This is not intended to be anything like a full answer, but rather a lay-engineers comment to tack onto Simon’s very nice explanation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When in descent mode with cyclic down the blades are in negative pitch to usual and airflow through them adds energy to them (up to some controlled limit) rather than transferring energy from them. The rotor becomes an energy store — a “winged flywheel.” Having the rotor at maximum allowed RPM in this mode maximises stored energy. Once you reach maximum allowed RPM the blades can be operated to maximise falling drag, subject to maintaining rotational speed — the rotor is akin to a large flat-plate. the machine will now fall at terminal velocity* for the maximum drag combination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you “flare” and raise the collective, blade pitch again becomes positive and you again have a &lt;em&gt;powered&lt;/em&gt; helicopter. &lt;em&gt;BUT&lt;/em&gt; it is powered by the inertial energy stored in the mass of the rotating blade assembly and you are going to use that up extremely fast — you have a few seconds of flying time, with rotor speed dropping as energy is taken from it. The flare procedure is designed to use the rotational stored energy in a manner which optimises the transition from pre flare velocities to post flare velocities. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;* &lt;strong&gt;Auto-rotation terminal velocity:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not researched this so there may be reasons that it is wrong, but based on many other scenarios for bluff falling objects it seems likely that fall rate will be close to what is predicted by the classic drag equation so Rotor falling drag or machine mass is defined by&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{1}{2} \rho C_d A V^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$\rho =$ air density ($1.2\ \mathrm{kg/m^3}$ near sea level)&lt;/li&gt;&#xA;&lt;li&gt;$A =$ area ($\mathrm{m}^2$)&lt;/li&gt;&#xA;&lt;li&gt;$V =$ velocity  ($\mathrm{m/s}$)&lt;/li&gt;&#xA;&lt;li&gt;$C_d =$ drag coefficient relative to flat plate, say 0.8 in this case&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Therefore $\mathrm{mass} \cdot g = 0.6 \cdot 0.8 \cdot A \cdot V^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and terminal velocity &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_{\mathrm{terminal}} = \sqrt{\frac{\mathrm{mass} \cdot 9.8}{A/2}}$$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Terminal auto-rotate velocity in $\mathrm{m/s}$ is then&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\sqrt{\frac{20 \cdot \mathrm{mass_{gross}}}{A_{\mathrm{rotor\ disk}}}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this is a guesstimate based on a range of assumptions, the general principle gives satisfyingly good albeit approximate results for objects as diverse as field, mice, bowling balls, skydivers and cargo parachutes.&#xA;(It only works for raindrops when you realise that they generally fall as a flattened disk like shape when at terminal velocity.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.robinsonheli.com/brochures/r22_brochure.pdf&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Robinson R22 Beta II&lt;/strong&gt;&lt;/a&gt;, 620 kg gross weight, 151 inch rotor radius.&#xA;Use 600 kg and 46 square metre rotor-disk area:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_t = \sqrt{\frac{20 \cdot 600}{46}} = 16\ \mathrm{m/s} = 58\ \mathrm{km/h}$$&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Looking further &amp;hellip;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can see I shouldn’t have started this. Fascinating. Time eating.&lt;br&gt;&#xA;The above formula turns out to give a somewhat high auto-rotate velocity, which is good.  Probably 50%+ higher than actual. Possibly due to lift from disk in forward gliding flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1,000 feet per minutes $\approx 5\ \mathrm{m/s}$.&#xA;Various pages mention auto-rotate descent figures of 1,300 to 1,800 fpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.unicopter.com/1001.html&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;Auto-rotation related calculator and MUCH MUCH more&lt;/strong&gt;&lt;/a&gt; - &lt;strong&gt;superb&lt;/strong&gt;.  Includes comments - &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A rotor in vertical autorotation has the same resistance as a parachute of the same diameter. This rate of descent is also approximately twice the hover-induced velocity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;2500 ft/min is a reasonable upper limit for larger helicopters, i.e., 13 m/s&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The $t/k$ ratio, which is the time in seconds that a rotor can lift the chopper when the engine stops. It is the ratio of $J\cdot\Omega^2$ divided by 4 times the power required in hover. (The 4 comes from the fact that one can only use half of the kinetic energy stored in the rotor system). Prouty uses a more complex formula that takes in account $C_l$ and $C_d$ of rotor system, but if you use the equation [$\mathrm{Power\ OGE} = (61\cdot10^{-3}/Dia_{rot}) \cdot \sqrt{m^3/ro})$ all in metric (with $ro = 1.225\ \mathrm{kg/m^3}$ at sea level], and divide the value obtained par 0.84 (for TR power, and Transmission losses), and plug this value into the t/k calculation, it works...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So $t/k = \frac{J\cdot\Omega^2}{4\cdot\mathrm{Power\ OGE}}$ in seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The $t/k$ of the Robinson R22 is 0.8 (far too low I agree), and practically, you want $t/k$ around 1.2 to 1.7 sec, so roughly twice the Robinson.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The UltraSport-254 helicopter has an extremely low disk loading and an autorotation descent rate of 900 ft/min. It is said that in autorotation it can land then liftoff and re-land using only the inertia in the rotors. &#xA;The Osprey V-22 has an extremely high disk loading. The test data indicate that the aircraft would impacted the ground at a rate of descent of about 3700 ft/min.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://philip.greenspun.com/flying/robinson-r22&quot; rel=&quot;nofollow&quot;&gt;Robinson R22 discussion&lt;/a&gt; - informative. Comments on auto rotation and much more.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Due to its light weight and low inertia rotor system, the R22 is not forgiving of pilot error or sluggishness. After an engine failure, real or simulated, you and the instructor will have 1.6 seconds to lower the collective and enter an autorotation. Any delay beyond 1.6 seconds will be fatal as the rotor speed, once decayed below 80 percent, cannot be recovered. :-(&#xA;&#xA;&lt;hr&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://helicopterflight.net/autorotation.htm&quot; rel=&quot;nofollow&quot;&gt;The Art of Autorotation&lt;/a&gt;&lt;br&gt;&#xA;Extremely good auto-rotation tutorial and discussion with a number of pointers to arcane knowledge. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Video - &lt;a href=&quot;https://www.youtube.com/all_comments?lc=Qu5L7S3H5rZMIg_dpuwRnvQE2JeDc-YD8bah--IWYJg&amp;amp;v=s6mbjY9ZbCY&quot; rel=&quot;nofollow&quot;&gt;R22 {almost} zero airspeed autorotation landing&lt;/a&gt; User comments useful. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.robinsonheli.com/price_lists_eocs/r22_pricelist.pdf&quot; rel=&quot;nofollow&quot;&gt;R22 pricelist&lt;/a&gt; - just for interest&lt;/p&gt;&#xA;" OwnerUserId="4371" LastEditorUserId="4371" LastEditDate="2016-09-22T13:28:38.950" LastActivityDate="2016-09-22T13:28:38.950" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14631" PostTypeId="1" AcceptedAnswerId="14633" CreationDate="2015-05-09T08:55:40.653" Score="10" ViewCount="2619" Body="&lt;p&gt;What is the main purpose of ADS-B? How do aircrafts interact with each other using them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it intended to replace the Traffic Collision Avoidance System (TCAS) or ground based Air Traffic Control (ATC)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, why they need the Global Navigation Satellite System (GNSS)? Are there other systems that has a dependency relationship with ADS-B?&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="3386" LastEditDate="2015-05-09T15:14:31.573" LastActivityDate="2018-02-09T05:37:44.453" Title="Is ADS-B intended to replace other traffic management systems?" Tags="&lt;air-traffic-control&gt;&lt;ads-b&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14632" PostTypeId="2" ParentId="14629" CreationDate="2015-05-09T10:08:15.397" Score="2" Body="&lt;ul&gt;&#xA;&lt;li&gt;Cat III A 600 feet (180 meters) Runway Visible Range (RVR)&lt;/li&gt;&#xA;&lt;li&gt;CAT III B 150 feet (46 meters) RVR&lt;/li&gt;&#xA;&lt;li&gt;CAT III C zero visibility&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;No decision height in any CAT III approach (CAT II is 100' and CAT I is 200')&lt;/p&gt;&#xA;" OwnerUserId="1304" LastEditorUserId="5517" LastEditDate="2015-07-23T12:48:10.770" LastActivityDate="2015-07-23T12:48:10.770" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14633" PostTypeId="2" ParentId="14631" CreationDate="2015-05-09T10:32:57.903" Score="14" Body="&lt;p&gt;For a short introduction on what ADS-B is and why it is called dependent see &lt;a href=&quot;https://aviation.stackexchange.com/a/213/19&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B is a surveillance technology whereby the aircraft broadcasts information about its identity, position, altitude and velocity of the aircraft to any interesting party. The position and velocity information is derived from GNSS (GPS). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B is not intended to replace TCAS, although in the future it will augment TCAS. The TCAS algorithm currently only uses distance and altitude to calculate whether there is a conflict and to determine the best conflict resolution strategy. With the more accurate ADS-B position available to the system as well, the number of TCAS interrogation can be reduced (the surveillance radio frequencies are getting congested in some areas) and the performance of TCAS can be improved. A new standard for this hybrid approach was &lt;a href=&quot;https://www.eurocae.net/eshop/catalog/product_info.php?products_id=358&quot; rel=&quot;noreferrer&quot;&gt;published&lt;/a&gt; &lt;a href=&quot;http://www.rtca.org/store_product.asp?prodid=1110&quot; rel=&quot;noreferrer&quot;&gt;in 2013&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may also be possible to have a passive TCAS-like system that does not require active interrogation but is purely depending on ADS-B. Currently a technical standard for a new &lt;a href=&quot;http://www.skybrary.aero/index.php/ACAS_X&quot; rel=&quot;noreferrer&quot;&gt;Airborne Collision Avoidance System&lt;/a&gt; (ACAS, the generic name for TCAS) is being developed in a joint RTCA / EUROCAE committee (RTCA SC-147 / EUROCAE WG-75), which will take advantage of more data offered by ADS-B. This new standard will eventually replace TCAS II.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 'TCAS light' for small aviation has also been developed based on ADS-B. It is called  Traffic Situation Awareness with Alerts (TSAA), a standard that was &lt;a href=&quot;http://www.rtca.org/store_product.asp?prodid=1136&quot; rel=&quot;noreferrer&quot;&gt;published&lt;/a&gt; &lt;a href=&quot;https://www.eurocae.net/eshop/catalog/product_info.php?products_id=375&quot; rel=&quot;noreferrer&quot;&gt;last year&lt;/a&gt;. Within the next couple of years we will see manufacturers start offering products based on this standard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ATC&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of ADS-B is neither to replace ground based ATC. But it will change the way ATC is done. ADS-B IN will improve the situation awareness of pilots; they will have a display of accurate positions of other aircraft. New procedures will allow pilots to maintain visual separation to other aircraft in marginal Visual Meteorological Conditions (VMC), where they currently would often lose sight of other traffic. A more advanced usage of ADS-B will be flight deck based interval management (FIM) where ATC will be able to instruct aircraft to 'follow that plane XX seconds behind for landing on runway YY'. A first technical standard for FIM is being worked on, it is intended to be published before the end of this year. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B is neither a replacement for all radars, although it will allow the number of radars to be reduced. For remote areas that currently do not have radar coverage because of the associated high costs, ADS-B will be a cost effective alternative. Over the oceans, satellite &lt;a href=&quot;http://www.aireon.com/Home&quot; rel=&quot;noreferrer&quot;&gt;ADS-B receivers&lt;/a&gt; will be able to provide surveillance, changing the way ATC is performed over the high seas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;GNSS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the examples above, it is easy to understand the requirements on the reliability of ADS-B are substantial. Not only must the system be able to deliver accurate position data, it must be able to deliver that data with high integrity. That means, the probability that the system transmits inaccurate position data, even when there is a failure in the system, must be extremely small. To achieve this, a positioning systems must be able to do internal cross checks to detect failures and not depend on possible erroneous inputs from humans. GPS can meet the position source requirements using Receiver Autonomous Integrity Monitoring (RAIM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ADS-B technical specifications have all been written in such a way that they do not explicitly require GNSS to be the position source, but at the moment it is the only system that meets the requirement effectively. Most certification documents are written with the assumption that a GNSS will be used to provide position data. Theoretically one could put another system forward, but the costs of certifying that would be very high. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-09T19:00:54.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14635" PostTypeId="1" AcceptedAnswerId="14645" CreationDate="2015-05-09T13:45:43.137" Score="18" ViewCount="1738" Body="&lt;p&gt;I was researching Jimmy Doolittle this morning, and I found this on &lt;a href=&quot;http://www.history.com/topics/world-war-ii/james-h-doolittle&quot; rel=&quot;noreferrer&quot;&gt;History.com&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To aid his record-breaking 1922 coast-to-coast flight, U.S. military&#xA;  strategist Jimmy Doolittle invented a funnel-and-tube-based &quot;pilot&#xA;  dehydrator&quot;—possibly the earliest airplane toilet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That led me to the question: What did they do &lt;em&gt;before&lt;/em&gt; 1922 when they felt like they had to go? &lt;/p&gt;&#xA;" OwnerUserId="6846" LastEditorUserId="6846" LastEditDate="2017-09-22T20:17:37.820" LastActivityDate="2017-09-25T08:20:17.063" Title="What did they do before on-board toilets?" Tags="&lt;aviation-history&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14636" PostTypeId="1" CreationDate="2015-05-09T14:16:08.560" Score="15" ViewCount="706" Body="&lt;p&gt;Does anyone know if Pacific Southwest Airlines (PSA) ever flew certain routes under VFR?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read &lt;a href=&quot;https://aviation.stackexchange.com/q/1743/62&quot;&gt;this question&lt;/a&gt; and I understand that Part 121 does allow for VFR flight, but my question is specific to PSA. I've heard they routinely flew low altitude VFR flights on shorter routes throughout California.&lt;/p&gt;&#xA;" OwnerUserId="8438" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-09-25T21:41:20.460" Title="Did Pacific Southwest Airlines ever operate flights under VFR?" Tags="&lt;airline-operations&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14637" PostTypeId="1" CreationDate="2015-05-09T15:21:35.443" Score="10" ViewCount="3143" Body="&lt;p&gt;I've noticed that the F-16I has these protrusions on the sides of its fuselage. What purpose do they serve?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KohVh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="14897" LastEditDate="2019-09-15T15:51:04.870" LastActivityDate="2019-09-15T15:51:04.870" Title="What are the protrusions on the sides of the fuselage of the F-16I?" Tags="&lt;feature-identification&gt;&lt;fuselage&gt;&lt;f-16&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14638" PostTypeId="1" AcceptedAnswerId="14641" CreationDate="2015-05-09T15:29:38.380" Score="9" ViewCount="2692" Body="&lt;p&gt;I understand that many fighters use drogue parachutes and wheel brakes. But aren't there other methods of slowing down after touchdown?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="1696" LastEditDate="2018-04-24T23:57:19.700" LastActivityDate="2018-04-24T23:57:19.700" Title="How do most fighters slow down after landing?" Tags="&lt;landing&gt;&lt;fighter&gt;&lt;jet&gt;&lt;parachute&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14639" PostTypeId="2" ParentId="14637" CreationDate="2015-05-09T15:34:02.680" Score="15" Body="&lt;p&gt;They are &lt;a href=&quot;https://en.wikipedia.org/wiki/Conformal_fuel_tank&quot; rel=&quot;noreferrer&quot;&gt;Conformal Fuel Tanks&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://israeli-weapons.com/weapons/aircraft/f-16i/F-16I.html&quot; rel=&quot;noreferrer&quot;&gt;http://israeli-weapons.com/weapons/aircraft/f-16i/F-16I.html&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Conformal Fuel Tanks (CFT)&lt;/em&gt; - These tanks are manufactured by the  &quot;Israel Aircraft Industries&quot;  and increase the aircraft's amount of internal fuel by 50%. Their purpose is to significantly prolong the aircraft's flight range and ability to remain in the air. The tanks are installed the plane's back and conform to it's figure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Israel does not have any heavy bombers, so they need the fighters to be capable of striking deep in enemy territory and since they can't be accompanied by tankers there, they need additional fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As jwenting mentioned in comment, unlike most conformal tanks that are removable on the ground, these are fitted permanently.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="718" LastEditDate="2015-05-10T00:34:01.720" LastActivityDate="2015-05-10T00:34:01.720" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14640" PostTypeId="1" AcceptedAnswerId="14642" CreationDate="2015-05-09T16:43:43.243" Score="7" ViewCount="2268" Body="&lt;p&gt;I understand carbonated drinks in allowed in cabin, but, is it allowed in air cargo transportation, when you ship in bulk?&lt;/p&gt;&#xA;" OwnerUserId="8440" LastEditorUserId="12891" LastEditDate="2016-05-17T08:52:10.253" LastActivityDate="2021-02-03T14:35:41.793" Title="Are carbonated drinks considered dangerous goods for air freight?" Tags="&lt;safety&gt;&lt;cargo&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14641" PostTypeId="2" ParentId="14638" CreationDate="2015-05-09T17:23:11.420" Score="15" Body="&lt;p&gt;The primary (and most effective) method to slow the jet down is aerobraking.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O62nL.jpg&quot; alt=&quot;F-16 Aerobrake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the T-38 at ~130 knots full aft stick is applied at a rate that prevents the jet from becoming airborne again.  The stick will be back towards the seat pan.  Fly the nosewheel down to the runway at ~100 knots and apply wheel brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the F-16 the max aerobraking occurs at 13 AOA with speed brakes extended.  You do not want to exceed 15 degrees of pitch angle to prevent scraping the burner can and speed brakes.  The speed brakes will not fully extend while the nosewheel is not on the runway (however, it can be overridden but increases the possibility that the speed brakes will scrape).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In either case you do not want to let the nosewheel fall.  You also do NOT apply wheel braking until the nosewheel is down.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorDisplayName="user3309" LastEditDate="2015-05-12T23:04:51.520" LastActivityDate="2015-05-12T23:04:51.520" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14642" PostTypeId="2" ParentId="14640" CreationDate="2015-05-09T17:33:54.863" Score="9" Body="&lt;p&gt;Each operator is of course entitled to apply stricter regulations, but there's no restriction against carbonated drinks in the IATA-DGR (based on the ICAO TI, which sets out the framework for dangerous goods regulations).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum amount of pure CO2 an operator may transport in approved packaging (iaw. IATA-DGR) is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In gaseous form (UN1013): 150 kg on cargo only aircraft, and 75 kg in passenger/cargo aircraft.&lt;/li&gt;&#xA;&lt;li&gt;In liquid form (UN2187): 500 kg on cargo only aircraft, and 50 kg in passenger/cargo aircraft.&lt;/li&gt;&#xA;&lt;li&gt;In solid form &quot;dry ice&quot; (UN1845): 200 kg for both cargo and passenger/cargo aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7172" LastActivityDate="2015-05-09T17:33:54.863" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="14643" PostTypeId="1" AcceptedAnswerId="14644" CreationDate="2015-05-09T17:51:10.820" Score="34" ViewCount="3901" Body="&lt;p&gt;I've been reading about &lt;a href=&quot;https://en.wikipedia.org/wiki/Time_of_useful_consciousness&quot;&gt;Time of Useful Consciousness&lt;/a&gt; (TUC), and it says that at FL 180, the time of useful consciousness is 20 to 30 minutes at rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I've been to a trip to Tibet, and we went on a bus trip around the places, and at one point the bus came to a mountain pass around 18,500 feet, and we all got off the bus, walked around, took pictures, and even ate lunch, so it was definitely not at rest. It was about 40 minutes to 1 hour, and I only felt slightly uncomfortable/out of breath.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the chart, I should have passed out, or at least become &quot;useless&quot;. Why didn't this happen? Are the charts simply very conservative and apply to, say, unfit, crumbling, old pilots?&lt;/p&gt;&#xA;" OwnerUserId="8357" LastEditorUserId="6919" LastEditDate="2015-05-11T23:16:12.703" LastActivityDate="2015-05-12T05:57:46.813" Title="Why are listed times of useful consciousness so low?" Tags="&lt;altitude&gt;&lt;hypoxia&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14644" PostTypeId="2" ParentId="14643" CreationDate="2015-05-09T18:17:41.247" Score="42" Body="&lt;p&gt;In short: acclimatization, both chronic and acute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During your Tibet-trip, you had probably spent days at high altitudes, allowing your body to acclimatize to the lower oxygen partial pressure (similar to how some elite endurance athletes prepare themselves for competition), by increasing your hemoglobin count (and other mechanisms), making you better prepared for the walk at 18,500 ft. This is an example of chronic acclimatization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A normal sea-level dweller will not have had the benefit of the same acclimatization phase in a depressurization situation (albeit a pilot could probably have some degree of acclimatization from continuously being exposed to higher than sea-level cabin altitudes), and will hence have a shorter TUC. The onset of the depressurization will also play a big part in determining your TUC. A slow depressurization will allow for some acute acclimatization, whilst a rapid depressurization will allow for none. The shock of a rapid depressurization will also decrease your TUC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The table on the Wikipedia page you quoted is the same (or very similar) to what you'll find in most Human Performance literature for airmen, and is, according the same Wikipedia page &quot;average TUC for healthy, young military pilots&quot;.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-09T18:23:07.217" LastActivityDate="2015-05-09T18:23:07.217" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14645" PostTypeId="2" ParentId="14635" CreationDate="2015-05-09T20:40:00.420" Score="15" Body="&lt;p&gt;Go to the toilet before departure, and hope you can find somewhere to land if nature calls suddenly :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same really as before a long car journey today...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course aircraft of that time didn't have very long endurance, so the situation wasn't likely to arise that you'd need to make a pit stop to let nature take its course. You'd have a scheduled stop anyway well before that.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="1696" LastEditDate="2017-09-22T21:58:55.530" LastActivityDate="2017-09-22T21:58:55.530" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14646" PostTypeId="2" ParentId="14643" CreationDate="2015-05-09T21:47:44.940" Score="22" Body="&lt;p&gt;At lower altitudes, &quot;useful&quot; consciousness doesn't end when you are unable to act.  Rather, what happens is that your ability to make sound decisions and carry them out effectively degrades: for example, instead of responding to an alarm buzzer by figuring out what's causing it, you might simply hit the &quot;silence&quot; button, or you might be so fixated on keeping the airplane flying straight-and-level that you don't notice the alarm, or you might be unable to concentrate on either task long enough to do anything effectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not familiar with aviation literature on the subject, but at &lt;a href=&quot;https://en.wikipedia.org/wiki/Mauna_Kea_Observatories&quot;&gt;Mauna Kea Observatories&lt;/a&gt; (14,000 feet), they found that providing supplemental oxygen to people working there greatly reduced the error rate.  See, for example, a &lt;a href=&quot;http://www.keckobservatory.org/recent/entry/hawaiis_coldest_steepest_job&quot;&gt;Keck Observatory article on the subject&lt;/a&gt;, or a &lt;a href=&quot;http://legacy.nrao.edu/alma/memos/html-memos/alma162/memo162.html&quot;&gt;study on the effects of altitude&lt;/a&gt; for a proposed Chilean observatory that heavily references Mauna Kea.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="1677" LastEditDate="2015-05-12T05:57:46.813" LastActivityDate="2015-05-12T05:57:46.813" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14647" PostTypeId="1" AcceptedAnswerId="14651" CreationDate="2015-05-10T01:50:43.483" Score="14" ViewCount="4392" Body="&lt;p&gt;I have been told that &lt;a href=&quot;http://en.wikipedia.org/wiki/Tailstrike&quot;&gt;tail strikes&lt;/a&gt; on take off and landing are rare but do occur.  I think, in my mind, the tail touching the ground at all would just make the tail fall off, but it appears I was wrong.  In most of cases of tail strikes I've read about the plane is able to either continue on it's journey or can simply circle back to the field it departed from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'm wondering, what do big commercial aircraft manufacturers (like &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747&quot;&gt;Boeing&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380&quot;&gt;Airbus&lt;/a&gt;) do to keep tail strikes from turning into a major disaster?  How do they engineer the plane to survive the incident?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-05-10T04:52:42.157" LastActivityDate="2015-06-02T23:36:18.980" Title="How do manufacturers engineer their aircraft to deal with tail strikes?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14648" PostTypeId="1" AcceptedAnswerId="14652" CreationDate="2015-05-10T03:37:29.093" Score="7" ViewCount="1255" Body="&lt;p&gt;I've heard many people say that a digital autopilot is better than its analog equivalent. How do the two differ in design and the way they control the plane?&lt;/p&gt;&#xA;" OwnerUserId="81" LastEditorUserId="7532" LastEditDate="2015-05-11T01:38:30.907" LastActivityDate="2015-05-11T01:38:30.907" Title="Why are digital autopilots better than analog?" Tags="&lt;autopilot&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14649" PostTypeId="1" CreationDate="2015-05-10T05:02:19.337" Score="7" ViewCount="1276" Body="&lt;p&gt;This is inspired by a lengthy set of comments on &lt;a href=&quot;https://aviation.stackexchange.com/questions/14647/how-do-manufacturers-engineer-their-aircraft-to-deal-with-tail-strikes&quot;&gt;this question&lt;/a&gt; (for reference).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been searching the internet high and low for reliable information on how many tail strikes occur per year for commercial passenger aviation, and I can't seem to turn up anything reliable.  Articles I've read range from saying they happen maybe once a year to several times a year, but none of them show hard numbers or list all incidents (&lt;a href=&quot;http://www.flyertalk.com/the-gate/blog/18769-the-tale-of-the-tail-strike-damaged-aircraft-crosses-ocean-%E2%80%94-and-no-one-realized-it.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://www.wsj.com/articles/SB10001424052748703951704576092371997568908&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://247wallst.com/special-report/2013/04/24/the-nine-most-common-airplane-accidents/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for a sampling.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anyone has verifiable hard numbers on this, I would love to see them...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-10T10:57:05.657" Title="How many commercial passenger aircraft suffer tail strikes in a given year?" Tags="&lt;safety&gt;&lt;accident-statistics&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14650" PostTypeId="2" ParentId="14647" CreationDate="2015-05-10T07:14:11.147" Score="5" Body="&lt;p&gt;Firstly, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_04/textonly/tr01txt.html&quot; rel=&quot;noreferrer&quot;&gt;this article from Boeing&lt;/a&gt; explains how tail strikes occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And&#xA;&lt;a href=&quot;https://www.google.co.uk/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CDMQFjAB&amp;amp;url=http%3A%2F%2Fwww.boeing.com%2Fcommercial%2Faeromagazine%2Farticles%2Fqtr_1_07%2FAERO_Q107_article2.pdf&amp;amp;ei=iANPVcD2OIKsUdmYgYAI&amp;amp;usg=AFQjCNFjo9mEKcEdOn68GM86h6S8iwOMBA&amp;amp;bvm=bv.92885102,d.d24&quot; rel=&quot;noreferrer&quot;&gt;this Boeing informational note&lt;/a&gt; gives more practical information on tail strikes and prevention:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A short excerpt from that note:&#xA;&quot;...some 777 models incorporate a tail strike protection system that uses a combination of software and hardware to protect the airplane. And some models of the 737, 767, and 777 have a tail skid that prevents damage from most takeoff tail strikes. However, these devices do not guarantee protection for landing tail strikes and some takeoff tail strikes. They also reduce tail clearance distances.&quot;&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-05-10T07:14:11.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14651" PostTypeId="2" ParentId="14647" CreationDate="2015-05-10T07:42:53.577" Score="14" Body="&lt;p&gt;During testing, the rear fuselage is protected by a beam made of oak or even steel to distribute the tail strike loads and to protect the aircraft skin.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/f976f.jpg&quot; alt=&quot;A340 during tail strike tests&quot;&gt;&#xA;A340 during tail strike tests. This one is literally blazing along the runway …&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For normal operations, the protection is removed. However, tail strikes must not cause flight-critical damage, so a few precautions are taken during design:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No hydraulic or electrical lines must run along the bottom of the rear fuselage.&lt;/li&gt;&#xA;&lt;li&gt;If there are still mechanical control elements like pushrods, they and their collapsing supports must not be close to the bottom of the fuselage.&lt;/li&gt;&#xA;&lt;li&gt;The tail strike location must be outside of the pressurized part of the fuselage.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main protection against tail strikes, however, is procedural: The &lt;a href=&quot;https://aviation.stackexchange.com/questions/12709/how-does-early-rotation-increase-the-likelihood-of-a-tail-strike-at-take-off&quot;&gt;rotation speed must be high enough&lt;/a&gt; to allow lift-off before a critical pitch attitude is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delta wing aircraft are much easier to over-rotate, so the Concorde used a retractable tailwheel for tail strike protection:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/HGaTy.jpg&quot; alt=&quot;BA Concorde tail from below with rear wheel extended&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-10T07:49:53.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14652" PostTypeId="2" ParentId="14648" CreationDate="2015-05-10T08:03:28.887" Score="9" Body="&lt;p&gt;Early autopilots would only control one degree of freedom. Starting with the yaw damper of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot;&gt;Me-262&lt;/a&gt;, they were a simple feedback loop involving a gyro, a single control surface and some damping circuitry. Example: A roll gyro was coupled to the ailerons and kept the wings level. Commanding a bank angle would simply shift the zero point of the gyro to a different angle, and some damping made sure that the movement was slow and did not overshoot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This, however, would neglect any cross coupling. Banking flight needs more thrust to keep altitude, but the roll autopilot would not &quot;know&quot; of engines or throttles, just ailerons. The same was true for analogue pitch and altitude hold systems which had a simple feedback loop with the throttle and the elevator, but no other controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern digital autopilots, starting with the one in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rockwell-MBB_X-31&quot;&gt;X-31&lt;/a&gt;, control all axes in parallel and use a multitude of sensors and feedback loops to control the whole aircraft in one go. This is much easier to achieve with digital control, and gives smoother responses since cross-coupling effects can be anticipated and corrected before they manifest themselves.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-10T17:04:54.827" LastActivityDate="2015-05-10T17:04:54.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14653" PostTypeId="2" ParentId="14649" CreationDate="2015-05-10T10:45:33.110" Score="4" Body="&lt;p&gt;A preliminary answer might be the results of &lt;a href=&quot;http://avherald.com/h?search_term=tailstrike&amp;amp;opt=0&amp;amp;dosearch=1&amp;amp;search.x=0&amp;amp;search.y=0&quot; rel=&quot;nofollow&quot;&gt;searching incident reports at AVHerald&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Accident    Ryanair B738 at London on Jul 29th 2014, tail strike on landing&#xA;Incident    Ryanair B738 at Alicante on Mar 27th 2013, tail scrape on takeoff&#xA;Report      Jazz DH8C at Gaspe on Sep 10th 2012, hard landing and tailstrike&#xA;Incident    Smartlynx Estonia A320 at Tallinn on Jul 31st 2014, tail strike on landing&#xA;Accident    Swiss A321 at Geneva on Mar 9th 2014, tail strike on landing&#xA;Incident    ANA B763 at Tokyo on Mar 13th 2014, suspected tailstrike on departure&#xA;Accident    TAROM B733 at Bucharest on Apr 4th 2011, tail strike&#xA;Accident    Lufthansa A333 at Chicago on Mar 5th 2013, undetected tailstrike on takeoff&#xA;Incident    Transavia B738 at Amsterdam on Apr 29th 2013, suspected tailstrike&#xA;Accident    Aeromexico B762 at Madrid on Apr 16th 2013, tail strike on takeoff&#xA;Accident    Titan B733 at Chambery on Apr 14th 2012, tail strike&#xA;Accident    Sata A313 at Ponta Delgada on Mar 2nd 2013, tail strike on landing&#xA;Report      Jetstar A320 at Sydney on Feb 6th 2012, thrust lever asymmetry during takeoff and early rotation&#xA;Accident    China Cargo B772 at Copenhagen on Apr 17th 2011, tail strike on go-around&#xA;Accident    Austrian A321 at Manchester on Dec 23rd 2011, tail strike during go-around&#xA;Incident    Air Atlanta A306 at East Midlands on Jan 10th 2011, tailstrike on landing, go-around with open thrust reverser&#xA;Incident    Air Atlanta A306 at East Midlands on Jan 10th 2011, tailstrike on landing, go-around with open thrust reverser&#xA;Accident    Emirates A345 at Melbourne on Mar 20th 2009, tail strike and overrun on takeoff&#xA;Accident    Gol B738 at Porto Alegre on Nov 16th 2011, tail strike on landing&#xA;Report      Lufthansa MD11 at Mumbai on Jun 11th 2011, tailstrike on landing&#xA;Accident    China Cargo B772 at Copenhagen on Apr 17th 2011, tail strike on go-around&#xA;Report      Kam Air DC86 at Manston on Aug 11th 2010, tail strike on takeoff&#xA;Accident    TUIFly B738 at Tenerife on Mar 27th 2011, rejected takeoff due to tailstrike&#xA;Report      Tunisair B736 at Paris on Oct 10th 2008, rejected takeoff after rotation&#xA;Accident    United Airlines B744 at Sydney on May 7th 2010, tail strike on takeoff&#xA;Accident    Northwest A320 at Denver on May 4th 2009, tail strike on landing&#xA;Incident    Austrian B763 at Beijing on Jan 29th 2010, tailscrape on takeoff&#xA;Accident    Northwest A320 at Denver on May 4th 2009, tail strike on landing&#xA;Report      Ryanair B738 at Dublin on Sep 11th 2008, tailstrike on takeoff&#xA;Crash       Avient Aviation MD11 at Shanghai on Nov 28th 2009, overran runway on takeoff&#xA;Report      Thomas Cook A332 at Montego Bay on Oct 28th 2008, mislaid manual leads to wrong takeoff speeds&#xA;Report      Thomson Airways B763 at Manchester on Dec 13th 2008, tail strike&#xA;Incident    PIA B743 at Lahore on Jun 23rd 2009, suspected tail strike leads to discovery of tail strike&#xA;Incident    Australian Air Express B463 at Brisbane on Oct 23rd 2008, tail strike on hard landing&#xA;Accident    Emirates A345 at Melbourne on Mar 20th 2009, tail strike and overrun on takeoff&#xA;Accident    Emirates A345 at Melbourne on Mar 20th 2009, tail strike and overrun on takeoff&#xA;Report      Aigle Azur A321 at Algiers on Jan 8th 2008, tailstrike during landing&#xA;Incident    Pegasus B738 at Cologne on Dec 20th 2008, tailstrike on takeoff&#xA;Report      Flybe DH8D at Paris on May 28th 2008, tailstrike&#xA;Report      My Travel A320 at Kos on Jul 5th 2007, very hard landing&#xA;Incident    Cargo B B742 at Brussels on Oct 27th 2008, tail strike on takeoff&#xA;Incident    Ryanair B738 at Dublin on Sep 11th 2008, tail strike on takeoff&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Incident    Comair (SA) B732 at Cape Town on May 3rd 2008, tail strike&#xA;Incident    Ryan Int B738 at Milwaukee on Mar 14th 2008, tailstrike on takeoff&#xA;Accident    RyanAir B738 at Stansted on Feb 18th 2008, tailstrike on takeoff&#xA;Accident    RyanAir B738 at Stansted on Feb 18th 2008, tailstrike on takeoff&#xA;Incident    Delta B767 at Moscow on Jan 26th 2008, tailstrike on takeoff&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Incident    LaudaAir B738 at Linz on Oct 2nd 2007, tailstrike at about taxi speed&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Accident    Swiss RJ100 at London City on Aug 18th 2007, tailstrike on landing&#xA;Incident    RyanAir B738 at Dublin on Mar 20th 2007, tailstrike during takeoff&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;You need to check some of these, some of them mention tailstrike where none occurred (e.g. inapppropriate pilot action due to fear of tailstrike)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may need to define tailstrike, maybe a controlled flight into terrain sometimes involves a tailstrike but wouldn't be categorised as such.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-10T10:57:05.657" LastActivityDate="2015-05-10T10:57:05.657" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14655" PostTypeId="2" ParentId="14635" CreationDate="2015-05-10T12:18:32.967" Score="8" Body="&lt;p&gt;Aircraft like the 1918 &lt;a href=&quot;http://en.wikipedia.org/wiki/Curtiss_NC&quot;&gt;Curtiss NC&lt;/a&gt; had sleeping quarters so I imagine they must have had arrangements for in-flight &quot;comfort breaks&quot;. It probably wasn't considered appropriate to write about it though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Curtiss_NC-4&quot;&gt;NC-4&lt;/a&gt; transatlantic flight in 1919 took 19 days and &lt;em&gt;&quot;included time for stops of numerous repairs and for &lt;strong&gt;crewmen's rest&lt;/strong&gt;&quot;&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer is we don't know, but we can imagine they made stops or carefully used containers provided (or improvised) for the purpose.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-05-10T12:18:32.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14656" PostTypeId="1" AcceptedAnswerId="14680" CreationDate="2015-05-10T12:38:38.957" Score="10" ViewCount="1384" Body="&lt;p&gt;I'm really interested in knowing the methods used by the Air-Traffic-Flow-Management (ATFM) providers to increase the throughput of the airspace by balancing safety, efficiency and cost. I've been reading different research papers and most of them conclude on using algorithms based on &lt;strong&gt;linear programming&lt;/strong&gt; to manage the arrival and departure slots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, there are many articles explaining a possible resolution of the Ground Holding Problem, that allocates departure slots so that no sector is violated, by using linear programming and mathematical optimization techniques. Airport capacity as well can be improved by the use of linear programming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that linear programming is based on minimizing/maximizing a certain objective function, subject to a set of constraints. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see that these techniques can be a good idea to have a big picture of an optimal configuration of slots, for instance. But are these linear programming algorithms actually used? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is linear programming so much effective to carry out air traffic management according to this method? What other methods are powerful and used nowadays to manage air traffic?&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="3859" LastEditDate="2019-10-24T12:33:36.433" LastActivityDate="2019-10-24T12:33:36.433" Title="Are Air Traffic Flow Management Algorithms mostly based on linear programming techniques?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;air-traffic-management&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14657" PostTypeId="1" AcceptedAnswerId="14658" CreationDate="2015-05-10T15:34:37.577" Score="19" ViewCount="3855" Body="&lt;p&gt;Attitude Indicators are essentially gyroscopes. Mechanical gyroscopes have a &quot;rigidity in space&quot; property, which allows them to preserve their orientation when the support rotates. However, like spinning tops, gyroscopes will also slowly right themselves up due to gravity; otherwise the AI will show pitch down as the plane travels forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I keep an airplane in a balanced turn long enough, is it possible that the gyroscope will right itself to the fake gravity, and show that I'm straight and level?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about ring laser gyroscopes?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1696" LastEditDate="2015-06-16T20:01:52.167" LastActivityDate="2015-06-16T20:01:52.167" Title="If I fly a balanced turn long enough, will the AI show I'm level?" Tags="&lt;flight-instruments&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14658" PostTypeId="2" ParentId="14657" CreationDate="2015-05-10T22:23:51.300" Score="7" Body="&lt;p&gt;No, because in a turn the local “level” continuously changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets say you are heading north and turning right. So your floor is banked to the east and the gyro is accumulating bias to east too. But after you make 90°, you are heading to the east and your bank is now to the south, so the gyro is accumulating bias to the south while the bias to the east is already reducing. So the gyro will never show precisely correct level, but it will never indicate level in the turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding whether ring laser gyroscope will behave the same, it is a bit more complicated. The righting of the gyroscope is &lt;em&gt;not&lt;/em&gt; inherent property of the gyroscope. It is added to compensate for &lt;em&gt;curvature and rotation of Earth&lt;/em&gt;. A gyroscope made not to right itself maintains the same axis of rotation &lt;em&gt;relative to distant stars&lt;/em&gt;. But as you fly along the curved surface of Earth, and as the Earth rotates with you, different stars will be getting into zenith. So the gyroscope has to be continuously adjusted to the local level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you have single gyroscope for use as attitude indicator, it needs a righting mechanism whether it is a mechanical or ring laser one and that mechanism will cause the same kind (and similar magnitude) of error in turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However a complete inertial navigation system can improve the precision. Such system knows how you move and so it can calculate how the local level, relative to distant stars, differs from the initial and can include this correction. It will still do some righting, using average acceleration, to correct for drift, but it can take the average over longer time, so the error in turns grows more slowly.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-05-10T22:23:51.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14659" PostTypeId="2" ParentId="14657" CreationDate="2015-05-10T23:12:21.727" Score="10" Body="&lt;p&gt;A gyroscopic Attitude Indicator will not build up long-term error simply because of its erection mechanism in an extended coordinated turn. However, all gyroscopes will accumulate error over time, which must be corrected in some fashion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A gyroscopic AI will display a &lt;a href=&quot;https://aviation.stackexchange.com/a/11925/136&quot;&gt;turning error of 3-5 degrees&lt;/a&gt; in a 180 degree turn. However, this precession is reversed in the second 180 degrees of a turn, so after 360 degrees, the precession is eliminated and the AI is correct again. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To explain why this is, first consider the design of the attitude indicator: the pendulous vanes exert an erecting force when the gyro is not vertical with respect to downward acceleration. &lt;img src=&quot;https://i.stack.imgur.com/yUQLB.png&quot; alt=&quot;Gyroscope emphasizing pendulous vanes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_65-15A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;(FAA AC 65-15A)&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This causes the gyro to erect itself over time, and would in fact do so incorrectly if the aircraft were kept on a constant heading (if, for example, flown uncoordinated on a constant heading.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in a coordinated turn, the case of the AI (including the pendulous vanes) rotates around the gyro. For the first half of the turn, the gyro is erecting in a particular direction. However, as the pendulous vanes move more than 180 degrees around the gyro, they add error opposite the original direction - removing the original error.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/NP8Kw.jpg&quot; alt=&quot;Diagram of gyroscopic instrument in two positions&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that while this fixes turning error in the long term, other sources of error are still in place. Precession caused by the fact that the gyroscope gimbals are not perfectly friction-free, which will vary in each individual instrument, will still happen - and the erection system will be unable to correct for it, as it's too busy causing and removing its own error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ring-laser gyro would be subject to the same problems, because it must still have a correction process of some sort. All gyroscopes, even perfect ones, are subject to apparent precession:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A freely spinning gyro tends to maintain its axis in a constant direction in space, a property known as rigidity in space or gyroscopic inertia. Thus, if the spin axis of a gyro were pointed toward a star, it would keep pointing at the star. Actually, the gyro does not move, but the earth moving &#xA;  beneath it gives it an apparent motion. This apparent motion is called apparent precession. The magnitude of apparent precession is dependent upon latitude. The horizontal component, drift, is equal to 15° per hour times the sine of the latitude, and the vertical component, topple, is equal to 15° per hour times the cosine of the latitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(FAA &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-18.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Navigator Handbook&lt;/a&gt;, p. 3-7)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any gyro, whether a ring-laser, MEMS, or gyroscopic, in a coordinated turn, will exhibit apparent precession and will have to be corrected over time if their only source of correction is acceleration.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-05-10T23:12:21.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14660" PostTypeId="1" AcceptedAnswerId="14668" CreationDate="2015-05-10T23:34:37.343" Score="17" ViewCount="2671" Body="&lt;p&gt;From a strictly legal standpoint, in the US (I'm also interested in Canada) can you (not should you) accept compensation to taxi an aircraft if you don't have a commercial pilot's license? If I was a mechanic with just a private license, could I charge for my time while taxiing an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="807" LastEditorUserId="62" LastEditDate="2015-05-11T15:17:33.257" LastActivityDate="2015-05-13T19:21:53.923" Title="Can you be paid to taxi an aircraft if you don't have a commercial license?" Tags="&lt;faa-regulations&gt;&lt;ppl&gt;&lt;taxiing&gt;&lt;cpl&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14661" PostTypeId="2" ParentId="14635" CreationDate="2015-05-11T00:34:44.317" Score="12" Body="&lt;p&gt;Linbergh was asked this very question after his famous transatlantic flight and his response... &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So Lindbergh explained that in his airplane his chair was made of wicker and there was a hole in it. And there was a funnel below that hole. And his waste, whenever nature called, would go down through there into sort of an aluminum can. And so he explained that and said that rather than show up with it in Le Bourget, the airport that he landed in, that he just dropped it over France.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.npr.org/blogs/waitwait/2012/03/02/147812749/on-transatlantic-bathroom-breaks&quot;&gt;Quote Credit&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-11T00:34:44.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14662" PostTypeId="1" CreationDate="2015-05-11T02:09:39.680" Score="3" ViewCount="767" Body="&lt;p&gt;I'm trying to estimate the &lt;a href=&quot;http://www.icao.int/Meetings/EnvironmentalWorkshops/Documents/Noise-Certification-Workshop-2006/Depitre_4.pdf&quot; rel=&quot;nofollow&quot;&gt;Effective Perceived Noise&lt;/a&gt; (EPNdB) of the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow&quot;&gt;GE9x&lt;/a&gt;. GE Aviation says that it will be within 8 dB margin of the &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/airport_aircraft_noise_issues/levels/&quot; rel=&quot;nofollow&quot;&gt;stage 5 noise regulations&lt;/a&gt;, can anyone confirm that?&lt;/p&gt;&#xA;" OwnerUserId="8446" LastEditorUserId="62" LastEditDate="2015-05-12T15:32:32.163" LastActivityDate="2015-05-12T15:32:32.163" Title="What's the EPNdB for large turbofan engines for stage 5 noise regulations?" Tags="&lt;faa-regulations&gt;&lt;engine&gt;&lt;noise&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14663" PostTypeId="1" AcceptedAnswerId="14685" CreationDate="2015-05-11T09:38:28.867" Score="4" ViewCount="3269" Body="&lt;p&gt;I know there are smoke detectors in aircraft but on what principle(s) do they generally work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial smoke detectors can use several different techniques like optical sensing, heat sensing and particle sensing. Do aircraft smoke detectors also work using one of these technologies or something different?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-05-12T15:28:22.337" LastActivityDate="2015-06-19T06:33:49.617" Title="On what principle(s) do aircraft smoke detectors work?" Tags="&lt;safety&gt;&lt;aircraft-systems&gt;&lt;smoke-detectors&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14664" PostTypeId="1" AcceptedAnswerId="14667" CreationDate="2015-05-11T09:44:17.487" Score="2" ViewCount="1315" Body="&lt;p&gt;Do big aircraft (e.g. Boeing 737 or Airbus 320) have carbon monoxide (CO) detectors installed in them? I don't know if the pressurized cabin means they aren't needed, but I do remember there are CO detectors in small planes and there are some reported accidents due to inhaling CO from engines.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-05-12T15:20:33.210" LastActivityDate="2015-05-12T15:20:33.210" Title="Do large aircraft have carbon monoxide detectors?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14665" PostTypeId="1" AcceptedAnswerId="14666" CreationDate="2015-05-11T09:58:29.017" Score="2" ViewCount="760" Body="&lt;p&gt;How are the smoke detectors in aircraft lavatories connected to the flight deck so the crew there can see the warning alarm? Do they have wires all the way from the lavatory to the flight deck, or are they connected in some other way?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="923" LastEditDate="2015-06-29T05:23:08.717" LastActivityDate="2015-06-29T05:23:08.717" Title="How are lavatory smoke detectors connected to the flight deck?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14666" PostTypeId="2" ParentId="14665" CreationDate="2015-05-11T10:08:48.847" Score="5" Body="&lt;h2&gt;Data Bus&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A quick Google search suggests the general approach is to minimise wiring by using a data-bus approach to carry information from multiple sources along a minimum number of wires&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.wseas.us/e-library/conferences/2010/Vouliagmeni/CSECS/CSECS-34.pdf&quot; rel=&quot;noreferrer&quot;&gt;ARINC 629 Data Bus Standard on Aircrafts&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In earlier analogue avionic systems the number of cables used to transfer information between the various&#xA;  system components was considerable. With these systems, at least one pair of wires has been required for each signal&#xA;  and so a typical installation requires several pairs of wires. With the equivalent digital systems, all the analogue signals&#xA;  are converted into their equivalent and are assigned unique address labels to ensure there are no conflicts. These&#xA;  signals are then transmitted down a single pair of wires, which makes up a data bus. Aircraft data bus systems allow a&#xA;  wide variety of avionics equipment to communicate with one another and exchange data. The type of language used on&#xA;  an aircraft data bus is known as the protocol. There are currently different data bus standards (protocols) that currently&#xA;  account for most of the avionics data interchange on today’s aircraft, and these are: ARINC 429, ARINC 629, MILSTD&#xA;  1553, MIL-STD 1773, CSDB and ASCB. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I imagine that smoke detectors are just one example of the types of sensor that are integrated into such data-bus systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect there are several data-bus systems for redundancy and perhaps to isolate different categories of data.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Further reading&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://leonardodaga.insyde.it/Corsi/AD/Documenti/ARINCTutorial.pdf&quot; rel=&quot;noreferrer&quot;&gt;ARINC 429&lt;/a&gt; as used on  A310/A320, A330/A340; 727, 737, 747, 757 767; MD-11 etc. &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.wseas.us/e-library/conferences/2010/Vouliagmeni/CSECS/CSECS-34.pdf&quot; rel=&quot;noreferrer&quot;&gt;ARINC 629&lt;/a&gt; as used on 777&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet&quot; rel=&quot;noreferrer&quot;&gt;AFDX&lt;/a&gt; as used on A380&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.can-cia.org/fileadmin/cia/files/icc/11/knueppel.pdf&quot; rel=&quot;noreferrer&quot;&gt;Smoke Detectors interfaced by a safety critical aircraft&#xA;based CAN-Bus Network&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-11T11:00:59.833" LastActivityDate="2015-05-11T11:00:59.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14667" PostTypeId="2" ParentId="14664" CreationDate="2015-05-11T10:19:51.140" Score="5" Body="&lt;p&gt;Haven't seen any. Cabin heating is done quite differently on jet aircraft than on pistons. Bleed air is taken from the engine before the combustion chamber, so engine exhaust can't end up in the cabin, even if there was a greater fault in the A/C packs.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-05-11T10:19:51.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14668" PostTypeId="2" ParentId="14660" CreationDate="2015-05-11T13:38:41.940" Score="6" Body="&lt;p&gt;I would say yes you can as per the FAR as I read them the limitations on a PPL are&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§61.113 (a) Except as provided in paragraphs (b) through (h) of this section, no person who holds a private pilot certificate may act as pilot in command of an aircraft that is carrying passengers or property for compensation or hire; nor may that person, for compensation or hire, act as pilot in command of an aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So you cant act as Pilot In Command for hire or if there are passengers on board (which in this case I assume there are not) however if we look at the FAR for the official definition of &amp;quot;Pilot In Command&amp;quot; we will find&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Pilot in command means the person who:&lt;/p&gt;&#xA;&lt;p&gt;(1) Has final authority and responsibility for the operation and safety of the &lt;strong&gt;flight&lt;/strong&gt;;&lt;/p&gt;&#xA;&lt;p&gt;(2) Has been designated as pilot in command before or during the &lt;strong&gt;flight&lt;/strong&gt;; and&lt;/p&gt;&#xA;&lt;p&gt;(3) Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the &lt;strong&gt;flight&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The question is does taxing count as a &amp;quot;Flight&amp;quot;. I would think it does not and moving the aircraft around is part of maintenance (thats how they log the hours on the trainer planes I rent). The FAR definitions section (§1.1) does not seem to contain one for &amp;quot;flight&amp;quot; so that may be open to interpretation. But as I read it you can taxi the aircraft for compensation as its not a &amp;quot;Flight&amp;quot; and thus you are not the Pilot In Command which is when the PPL rules would come into play in my opinion.&lt;/p&gt;&#xA;&lt;p&gt;However section §65.81 states&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;However, he may not supervise the maintenance, preventive maintenance, or alteration of, or &lt;strong&gt;approve and return to service&lt;/strong&gt;, any aircraft or appliance, or part thereof, for which he is rated unless he has satisfactorily performed the work concerned at an earlier date.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The key line (Bolded) is return to service. If Taxing counts as returned to service then (unless rated to do so) you may not be able to for this reason (nothing to do with compensation).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; I am not a lawyer nor an aircraft mechanic and can not guarantee that my assumptions are correct. The opinions stated above should not be used as official legal advice and there may be more information in the FAR that I have not come across. This was compiled after some quick reading and searching in the assumed correct places.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Note 2:&lt;/strong&gt; I would assume that in a commercial setting (and really any setting) there are some insurance implications to this kind of operation (especially with large aircraft). This may almost be a bigger concern than the legality of it (although both are important). You would not want to get into the situation where you may be legally allowed to drive the plane on the tarmac but are not covered by the company's insurance. Should you get into an accident you or your shop may become liable for the damages.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-11T20:55:12.177" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14669" PostTypeId="1" AcceptedAnswerId="14672" CreationDate="2015-05-11T14:28:44.317" Score="21" ViewCount="6346" Body="&lt;p&gt;I've noticed that there isn't any type of hatch/plug door near the canopy of the B-1B Lancer. How do pilots enter and exit the aircraft? &lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="14897" LastEditDate="2019-09-05T12:11:23.247" LastActivityDate="2019-09-05T12:11:23.247" Title="How do pilots board the B-1B Lancer?" Tags="&lt;aircraft-design&gt;&lt;doors&gt;&lt;rockwell-b-1-lancer&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14670" PostTypeId="2" ParentId="14669" CreationDate="2015-05-11T14:39:33.440" Score="19" Body="&lt;p&gt;This picture shows a ladder behind the front landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8bVf2.jpg&quot; alt=&quot;Ladder&quot;&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/8/1/6/1561618.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="7952" LastEditorUserId="65" LastEditDate="2015-05-11T14:45:38.440" LastActivityDate="2015-05-11T14:45:38.440" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14671" PostTypeId="1" AcceptedAnswerId="14673" CreationDate="2015-05-11T14:41:59.697" Score="19" ViewCount="8300" Body="&lt;p&gt;The nose landing gear of the Airbus A320-200 was jammed, but the tires were perpendicular to the fuselage. How did that happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TJLay.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="4067" LastEditDate="2015-05-11T18:21:53.013" LastActivityDate="2021-03-07T02:09:16.133" Title="How did the nose landing gear of JetBlue Flight 292 get stuck sideways?" Tags="&lt;emergency&gt;&lt;landing-gear&gt;&lt;airbus&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14672" PostTypeId="2" ParentId="14669" CreationDate="2015-05-11T14:44:09.033" Score="27" Body="&lt;p&gt;The crew of &lt;a href=&quot;http://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;noreferrer&quot;&gt;Rockwell B-1 Lancer&lt;/a&gt; (4 in total) enter or exit the cockpit from the underside, using a ladder. It can be seen in &lt;a href=&quot;https://youtu.be/aYqKZsM0kU0?t=1m20s&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture shows the ladder (the one on the right):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/v51PX.jpg&quot; alt=&quot;Cockpit enterance&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.afcent.af.mil/Units/455thAirExpeditionaryWing/Photos/tabid/238/igphoto/2000186381/Default.aspx&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Image Source&lt;/em&gt;&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the top of the ladder, there is a door, which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0GGfO.jpg&quot; alt=&quot;entry door&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/001-100/awa001-B-1/00.shtm&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Image Source&lt;/em&gt;&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-05-11T15:10:54.600" LastActivityDate="2015-05-11T15:10:54.600" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14673" PostTypeId="2" ParentId="14671" CreationDate="2015-05-11T14:52:05.007" Score="20" Body="&lt;p&gt;According to the complete &lt;a href=&quot;http://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief2.aspx?ev_id=20050927X01540&amp;amp;ntsbno=LAX05IA312&amp;amp;akey=1&quot;&gt;NTSB report&lt;/a&gt;, following is a summary of what had caused the nose landing gear (NLG) to rotate 90° on &lt;a href=&quot;http://en.wikipedia.org/wiki/JetBlue_Airways_Flight_292&quot;&gt;Flight 292&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During flight, Brake Steering Control Unit (BSCU) performs&lt;sup&gt;1&lt;/sup&gt;&#xA;  cyclic tests which slightly rotates NLG from the 0° position. Due to&#xA;  this &lt;em&gt;fatigue&lt;/em&gt;, two of the four anti-rotation lugs on the NLG upper&#xA;  support assembly fractured and separated. This allowed NLG to deviate&#xA;  from the 0° position. Another contributing factor was BSCU system&#xA;  logic, which prevented NLG from centering. Also contributing was the&#xA;  lack of a procedure to attempt to reset the BSCU system under these&#xA;  conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airlinesafety.com/editorials/JetBlueLAX.htm&quot;&gt;This website&lt;/a&gt; has some nice pictures of nose landing gear before and after the landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A summary of the &lt;a href=&quot;http://investigativereportingworkshop.org/flying-cheap/incident/20050927X01540/1/&quot;&gt;investigation can be found here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;em&gt;BSCU has other functions too.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-05-12T14:42:46.237" LastActivityDate="2015-05-12T14:42:46.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14674" PostTypeId="2" ParentId="14662" CreationDate="2015-05-11T16:21:16.837" Score="4" Body="&lt;p&gt;What the FAA is calling &quot;Stage 5&quot; is the ICAO Chapter 14 regulations. These do no go into effect until 2017 or 2020, but that means it would be applicable for future engines such as the GE9X.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cumulative EPNdB margin for Chapter 14 is Chapter 4 +7, or Chapter 3 +17. The exact EPNdB value &lt;a href=&quot;http://www.icao.int/Meetings/Green/Documents/day%201pdf/session%202/2-Dickson.pdf&quot; rel=&quot;nofollow&quot;&gt;depends on takeoff weight&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-11T16:21:16.837" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14675" PostTypeId="1" AcceptedAnswerId="14677" CreationDate="2015-05-11T16:31:48.407" Score="18" ViewCount="1918" Body="&lt;p&gt;A simple question that I could not find an answer to:&lt;/p&gt;&#xA;&lt;p&gt;When is a sailplane a sailplane (from a regulatory point of view), especially a powered one of the TMG (touring motor glider) variety?&lt;/p&gt;&#xA;&lt;p&gt;EASA has some quite simple &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/Annexes%20to%20Regulation.pdf&quot; rel=&quot;noreferrer&quot;&gt;definitions&lt;/a&gt;, presumably modelled over the similar ones from ICAO, according to which:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;‘Sailplane’ means a heavier-than-air aircraft that is supported in&#xA;flight by the dynamic reaction of the air against its fixed lifting&#xA;surfaces, the free flight of which does not depend on an engine.&lt;/p&gt;&#xA;&lt;p&gt;‘Powered sailplane’ means an aircraft, equipped with one or more&#xA;engines having, with engine(s) inoperative, the characteristics of a&#xA;sailplane.&lt;/p&gt;&#xA;&lt;p&gt;‘Touring motor glider’ means a specific class of powered sailplane&#xA;having an integrally mounted, non-retractable engine and a&#xA;non-retractable propeller. It shall be capable of taking off and&#xA;climbing under its own power according to its flight manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From this simple chain of definitions, it would seem that, for instance, a Cessna 152 could be classified as a TMG: It can take off and climb under its own power, and with the (non-retractable) engine inoperative it will do free flight sustained by its &amp;quot;fixed lifting surfaces&amp;quot;, otherwise known as wings.&lt;/p&gt;&#xA;&lt;p&gt;Since a Cessna 152 is not normally seen as a glider, I presume that there are more rules that need to be respected before a plane can be called a glider (or sailplane in EASA's classification).&lt;/p&gt;&#xA;&lt;p&gt;I know that &lt;a href=&quot;http://easa.europa.eu/certification-specifications/cs-22-sailplanes-and-powered-sailplanes&quot; rel=&quot;noreferrer&quot;&gt;CS-22&lt;/a&gt; contains the specifics, but is there a simple set of rules to determine if an aircraft belongs to the class of (powered) sailplanes as opposed to normal aeroplanes?&lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-11-07T13:19:41.220" Title="When is a sailplane a sailplane?" Tags="&lt;easa-regulations&gt;&lt;glider&gt;&lt;sailplane&gt;&lt;tmg&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14676" PostTypeId="2" ParentId="14675" CreationDate="2015-05-11T17:17:55.167" Score="3" Body="&lt;p&gt;The easiest way to find out for a particular aircraft type is to check its (TCDS) Type Certificate Data Sheet. In it, you will find its certification basis and airworthiness category (CS-22, CS-23, CS-25, CS-VLA etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EASA TCDS's are available for free at:&#xA;&lt;a href=&quot;https://easa.europa.eu/document-library/type-certificates&quot; rel=&quot;nofollow&quot;&gt;https://easa.europa.eu/document-library/type-certificates&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA TCDS's are also available for free at:&#xA;&lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow&quot;&gt;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameSet&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you search the FAA TCDS database for Cessna 152, you will find its certification basis is CS-23 (&quot;Normal, Utility, Aerobatic and Commuter Aeroplanes&quot;) and not CS-22 (&quot;Sailplanes and Powered Sailplanes&quot;). To determine whether Cessna 152 could actually be type certified iaw CS-22 one would have to consult CS-22. I highly suspect that it contains weight limits, maximum energy and/or other limits that would bar the Cessna 152.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your reading pleasure:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/14B9F17E0CDCC2AE862578BF004875BE?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;FAA TCDS 3A19 (C152)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://easa.europa.eu/system/files/dfu/EASA-TCDS-A.074_Schempp--Hirth_Duo_Discus_T-05-25112009.pdf&quot; rel=&quot;nofollow&quot;&gt;EASA TCDS A.074 (Duo Discus T)&lt;/a&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://easa.europa.eu/document-library/certification-specifications/cs-22-initial-issue&quot; rel=&quot;nofollow&quot;&gt;EASA CS-22&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://easa.europa.eu/document-library/certification-specifications/cs-23-initial-issue&quot; rel=&quot;nofollow&quot;&gt;EASA CS-23&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-11T17:38:04.877" LastActivityDate="2015-05-11T17:38:04.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14677" PostTypeId="2" ParentId="14675" CreationDate="2015-05-11T18:20:14.127" Score="19" Body="&lt;p&gt;There are indeed several steps between a pure glider and a powered aircraft. The criteria were historically quite simple:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Gliders with an auxiliary engine, which is just for getting them home in adverse weather, but not powerful enough for take-off. The propeller is in almost all cases retractable, so their aerodynamics is identical to their pure glider version, apart from a slightly higher minimum wing loading.&lt;/li&gt;&#xA;&lt;li&gt;Motorgliders with an engine powerful enough for autonomous take-off, but with aerodynamics which gives them less than 1 m/s minimum sink with the engine switched off. This minimum sink decides if they are still powered gliders. This would be the TMG category.&lt;/li&gt;&#xA;&lt;li&gt;Powered aircraft with an unpowered minimum sink speed in excess of 1 m/s. The Cessna 152 belongs into this category.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With the introduction of glassfiber motorgliders with their higher wing loading, the minimum sink rule could not be maintained, and manufacturers lobbied for a change in regulations. As it currently stands, &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/CS-22_Amendment%201%20revised.pdf&quot; rel=&quot;noreferrer&quot;&gt;CS-22&lt;/a&gt; defines sailplanes to be within its scope if the maximum weight is below 750 kg. Powered sailplanes must not have more than two occupants, weigh 850 kg or less and have a span loading of 3 kg/m² (mass per span squared) or less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CS 22.71 restricts minimum sink in unpowered flight to 1.0 m/s for single seaters and 1.2 m/s for two seaters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that suitable instrumentation should also be added for a motor glider to be counted as a sailplane, such as a &lt;a href=&quot;http://en.wikipedia.org/wiki/Variometer&quot; rel=&quot;noreferrer&quot;&gt;variometer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-11-07T13:19:41.220" LastActivityDate="2017-11-07T13:19:41.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14678" PostTypeId="2" ParentId="381" CreationDate="2015-05-11T20:32:38.487" Score="3" Body="&lt;p&gt;They're not unheard of, as from your examples. Like any design, they have advantages and disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Typically more aerodynamic, and lighter, than a droptank of similar capacity.&lt;/li&gt;&#xA;&lt;li&gt;Carried closer to the fuselage than hardpoint droptanks, reducing roll moment, increasing maneuverability.&lt;/li&gt;&#xA;&lt;li&gt;Doesn't take up hardpoints desired for munitions (the primary reason the F-15E uses them is that it wouldn't have a useful range carrying 2000lb Mk-82s otherwise)&lt;/li&gt;&#xA;&lt;li&gt;Typically allows more fuel storage than the centerline droptank (the only other location that isn't usually a munitions hardpoint)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aerodynamics are still negatively impacted&lt;/li&gt;&#xA;&lt;li&gt;Cannot be jettisoned mid-flight for weight/drag advantage&lt;/li&gt;&#xA;&lt;li&gt;When empty of liquid fuel, CFTs can still contain a combustible vapor which could explode given a hit that might otherwise do only superficial damage (most modern designs use a bladder to contain the fuel and minimize vapor release into the CFT shell)&lt;/li&gt;&#xA;&lt;li&gt;Not all airframes tolerate CFTs of a meaningful size without significant changes in handling. The F-16I's performance is apparently unaffected by the additional 460 gallon-capacity CFTs, but the F-15E/I/SK, despite the airframe's air-superiority pedigree, is known to be at a disadvantage in a dogfight to the F-15C, the USAF's primary air-superiority variant.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-05-11T20:32:38.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14680" PostTypeId="2" ParentId="14656" CreationDate="2015-05-12T06:53:32.763" Score="8" Body="&lt;p&gt;Linear programming (LP) is an optimization method that finds the highest (or lowest) possible value of a set of linear equations given a number of linear constraints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of objectives in Air Traffic Management that may be described by linear equations. Runway throughput for example: twice as many aircraft can be seen as &quot;twice as good&quot;. Or delay: one minute of delay of a passenger aircraft with 400 passengers is as bad as 2 minutes of delay for a passenger aircraft with 200 passengers (both have 400 passenger-minutes-of-delay). Mathematical models based on these linear relationship can help to make decisions for air traffic controllers/planners. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are obvious limitations to linear programming. Not everything can be modeled as a linear relationship. Often the relations are more complex and linear models will be a poor fit because the relationship is not linear at all. In ATFM modelling, usually binary integer variables are used that can only take values of zero or one, thus a Binary Integer Linear Program is solved (BIP). And is 40 minutes of delay of a 10 passenger aircraft as bad as 1 minute of delay of a 400 passenger aircraft? These kind of relationships tend to prevent the small aircraft from ever taking off: it always pays off to let a bigger aircraft jump the queue. Perhaps a quadratic component in the  'cost-function' would bring a solution here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore more advanced models are needed. Methods like Integer Linear Programming (ILP), Mixed Integer Linear Programming, Mixed Integer Quadratic Programming and more advance optimization algorithms are used as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another problem is that while these optimization methods may be able to find a best possible strategy, they are not necessarily easy to understand. Air traffic controllers don't like to be just told what to do, they need to understand why a strategy is proposed so they can think ahead and create what-if scenarios. It is impossible to program every what-if scenario in the optimization model, so at times the controller will need to deviate from the proposed solution. Without understanding what the algorithm had planned, it is difficult for a controller to predict the knock-on effects of his deviation from the proposed plan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early arrival management software worked reasonably well when the weather was nicely playing along, but gave hopelessly wrong suggestions when a couple of thunderstorms would render the normal approach routes unusable. Flexibility and two way communication between the system and the controller is essential to make a good product, there is much more to it than choosing the right optimization algorithm.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1696" LastEditDate="2015-05-12T15:29:18.420" LastActivityDate="2015-05-12T15:29:18.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14681" PostTypeId="2" ParentId="14656" CreationDate="2015-05-12T15:01:47.280" Score="4" Body="&lt;p&gt;In Europe, the Network Management uses the Computer-Assisted-Slot-Allocation (CASA) algorithm in the &lt;a href=&quot;https://www.eurocontrol.int/articles/enhanced-tactical-flow-management-system-%E2%80%93-etfms&quot; rel=&quot;nofollow noreferrer&quot;&gt;Enhanced Tactical Flow Management System&lt;/a&gt; to allocate the departure slots. The CASA algorithm is a &lt;strong&gt;heuristic&lt;/strong&gt; that follows the 'first-planned-first-served' principle and shifts departure timeslots of flights that would otherwise violate sector capacities. Eurocontrol describes the CASA Algorithm in the &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/content/documents/nm/network-operations/HANDBOOK/atfcm-users-manual-current.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Traffic Flow and Capacity Management Users Manual&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In accordance with the principle of ‘First Planned - First Served’ the&#xA;system extracts all the flights entering the specified airspace and&#xA;sequences them in the order they would have arrived at the airspace in&#xA;the absence of any restriction.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;In addition to this fundamental process, a number of other mechanisms&#xA;will act to compensate for factors such as late received flight plans&#xA;and modifications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is not the same as Linear Optimization.&lt;/p&gt;&#xA;" OwnerUserId="3859" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-12T15:01:47.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14683" PostTypeId="2" ParentId="14623" CreationDate="2015-05-12T15:27:46.027" Score="1" Body="&lt;p&gt;Good answers, but let me make it short and simple.&#xA;The tail (empenage) mainly contains the vertical stabilizer and the horizontal stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=WWeLJHaXd8M&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;This video&lt;/em&gt;&lt;/a&gt; shows what happens when the vertical stabilizer is lost.&#xA;The plane has no way to stay pointed into the wind - very bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the horizontal stabilizer is lost, the plane instantly noses down.&#xA;(I tried to find the video of the dam-busters practice where the Lancaster bomber is going along above the water.&#xA;It drops the cylinder, which hits the water, bounces up, and slices off the tail of the bomber, which noses into the water, at 100+ mph.)&lt;/p&gt;&#xA;" OwnerUserId="395" LastActivityDate="2015-05-12T15:27:46.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14684" PostTypeId="2" ParentId="14638" CreationDate="2015-05-12T15:33:06.737" Score="7" Body="&lt;p&gt;Another way to slow fighter jets down, is by using airbrakes.&#xA;These are basically two big flaps (usually located at the end of the aircraft) that extend into the flow. I think the airbrakes do most of the braking in the approach phase (as it is a good way to dissipate kinetic energy fast), but i'm pretty sure they're also used to slow down during the roll out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an image showing an F-16 landing with the airbrakes extended, the two protruding flaps at the end are the airbrakes.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/tmk6i.jpg&quot; alt=&quot;F-16 Airbrakes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bonus, here's a picture of one of the first airbrakes in the book Popular Science (1932):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9ziCw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-05-12T15:46:32.490" LastActivityDate="2015-05-12T15:46:32.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14685" PostTypeId="2" ParentId="14663" CreationDate="2015-05-12T15:37:28.230" Score="5" Body="&lt;p&gt;The typical aircraft smoke detector works using optical sensing which exploits the Tyndall light scattering effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Boeing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kcmlA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q2/3/img/AERO_Q211_article_03_04.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An LED illuminates a sample of air while a light sensor, which is not in line-of-sight with the LED, looks at the same sample of air. If enough light is scattered by smoke particles then the detector will signal an alarm.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="3201" LastEditDate="2015-06-19T06:33:49.617" LastActivityDate="2015-06-19T06:33:49.617" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14686" PostTypeId="2" ParentId="12261" CreationDate="2015-05-12T16:11:59.023" Score="29" Body="&lt;p&gt;Yes, it has been done before in an even larger aircraft, the Boeing 367-80, &lt;a href=&quot;http://community.seattletimes.nwsource.com/archive/?date=19900228&amp;amp;slug=1058594&quot;&gt;very famously by &quot;Tex&quot; Johnston on August 7, 1955&lt;/a&gt;. This aircraft was the prototype for the Model 707. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a barrel roll maneuver is properly performed the aircraft remains in a positive-G state, so no &quot;inverted flight&quot; is experienced by the aircraft. According to the &lt;a href=&quot;https://www.iac.org/legacy/aerobatic-figures#BarrelRolls&quot;&gt;International Aerobatic Club&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Barrel roll is a combination between a loop and a roll. You complete one loop while completing one roll at the same time. The flight path during a barrel roll has the shape of a horizontal cork screw. Imagine a big barrel, with the airplanes wheels rolling along the inside of the barrel in a cork screw path. During a barrel roll, the pilot always experiences positive Gs. The maximum is about 2.5 to 3 G. The minimum about 0.5 G.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2015-05-12T16:21:03.257" LastActivityDate="2015-05-12T16:21:03.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14687" PostTypeId="2" ParentId="12261" CreationDate="2015-05-12T16:16:21.193" Score="12" Body="&lt;p&gt;Yes, and its happened at least &lt;a href=&quot;https://www.youtube.com/watch?v=AaA7kPfC5Hk&quot;&gt;once in a -80&lt;/a&gt; which eventually became the 707. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It became so legendary that rumor has it &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boeing Chief Test Pilot John Cashman stated that just before he piloted the maiden flight of the Boeing 777 on June 12, 1994, his last instructions from then-Boeing President Phil Condit were &quot;No rolls.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-12T16:16:21.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14689" PostTypeId="1" CreationDate="2015-05-12T19:02:54.967" Score="0" ViewCount="383" Body="&lt;p&gt;As the question says, which is the accidental cause most feared (in general) by the flight crews and what's the reason of it? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from hijacking, pilot incapacity or that kind of issues, I am referring to causes like aircraft systems failure, fire on cabin, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Observation:&lt;/strong&gt; I'm not asking this question to be an opinion question, since I want to know in general, what is this cause and reason(s) to be the most feared accidental cause.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastActivityDate="2015-05-12T21:08:52.683" Title="What is (are) the accidental cause(s) most feared by the flight crew?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="3" ClosedDate="2015-05-12T23:48:42.123" ContentLicense="CC BY-SA 3.0" />
  <row Id="14690" PostTypeId="1" AcceptedAnswerId="14694" CreationDate="2015-05-12T19:11:12.693" Score="46" ViewCount="166387" Body="&lt;p&gt;When I'm reading something about jet engines, it's common to see references to N1 and N2. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never fully understood what N1 and N2 are on engine instruments and how they relate to thrust and the position of the throttle.&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="62" LastEditDate="2015-05-13T13:13:09.847" LastActivityDate="2019-01-21T14:47:14.177" Title="What are N1 and N2?" Tags="&lt;jet-engine&gt;&lt;flight-instruments&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="14691" PostTypeId="2" ParentId="14690" CreationDate="2015-05-12T19:19:44.370" Score="39" Body="&lt;p&gt;N1 and N2 are the rotational speeds of the engine sections expressed as a percentage of a nominal value. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is similar to the revolutions per minute (RPM) of a piston engine, expressed in percentage instead of in the actual rate of rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are different because they are characteristic on two-spool engines (see the figure below). The first spool is the low pressure compressor (LP), that is N1 and the second spool is the high pressure compressor (HP), that is N2. The shafts of the engine are not connected and they operate separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Turbofan_operation.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5xWmS.png&quot; alt=&quot;Two-spool engine&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Image credit: &lt;a href=&quot;http://en.wikipedia.org/wiki/User:Emoscopes&quot; rel=&quot;noreferrer&quot;&gt;Emoscopes&lt;/a&gt; / Wikimedia&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="6919" LastEditDate="2015-05-14T03:20:12.450" LastActivityDate="2015-05-14T03:20:12.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14693" PostTypeId="2" ParentId="2862" CreationDate="2015-05-12T20:12:04.640" Score="3" Body="&lt;p&gt;Note, my answer that follows is per the US, and having been involved and discussed various naming of fixes and routes. Paid sponsorship doesn't happen. Usually it's the ATC facility that suggests names, and check the existing and reserved names lists.. For SIDs/STARs, the divide is usually the TRACON names the SIDs and the Center names the STARS. For random fixes that don't have to be as pronounceable(lots of RNAV approach fixes/intermediate fixes on arrivals), they can just be randomly assigned as long as they stand a chance of being able to be pronounced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers have a sense of humor and will see what they can get away with in terms of naming fixes. They have been named for people, both controllers, or people from the area. They can be a joke like the above mentioned ITAWT ITAWA PUDYE TTATT. Though a lot of the more historical fixes on Victor and Jet Airways are named for towns or features they're near.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-05-12T20:12:04.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14694" PostTypeId="2" ParentId="14690" CreationDate="2015-05-12T20:36:26.240" Score="38" Body="&lt;p&gt;Conceptually, N1 is the fan (or, fan &lt;em&gt;speed&lt;/em&gt;) and is most related to your thrust (since the fan produces more thrust than the core on today's big motors). The N2 is the engine core, and the N2 gauge is used mainly during engine start: on initial starter engagement, the N2 starts turning first, and things like adding fuel+ignition and then later disengaging the starter are based on specified N2 speeds. As long as you have N1 rotation before lighting the engine off, N1 isn't all that important during the start. But once it is running, power is generally set with reference to the N1 (or fuel flow or EGT or EPR) rather than the N2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V0PRs.jpg&quot; alt=&quot;Picture of 727 engine instruments&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This picture of 727 instruments shows, from top to bottom, the N1, EPR, EGT, N2, and Fuel Flow indicators.  You can tell (hopefully) how the N1 and N2 are both tachometers, showing percentages instead of values, because it's a lot easier to talk about 52% N2 than 6350 N2 RPM.  The picture below shows an example of the engine stack displayed on a modern EICAS panel, with the N1 and the EGT displayed prominently, and everything else just shown as digital values (with no EPR indication in this aircraft).  This is a typical in-flight presentation, showing you the two things you most care about with large displays, and everything else available if you really need it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LqHyK.gif&quot; alt=&quot;EICAS engine display&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-12-22T23:51:30.053" LastActivityDate="2016-12-22T23:51:30.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14695" PostTypeId="2" ParentId="14689" CreationDate="2015-05-12T20:55:42.167" Score="6" Body="&lt;p&gt;What crews &lt;em&gt;should&lt;/em&gt; be most concerned with is indeed crew error.  In the 1930's and 1940's, more accidents were caused by mechanical failures -- things failed that made the airplane unrecoverable.  Several decades ago, crew errors became the larger source of accidents, where a flyable aircraft (albeit with perhaps some issue, but flyable nevertheless) crashed because the crew did something that made the situation worse.  The hardware these days is pretty darned reliable, and if &quot;you&quot; do what you're supposed to do, chances are really excellent that you can get it on the ground safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, pilot psychology plays a major role in answering the question, since pilots strongly prefer to be &quot;in control.&quot;  Or, less formally, we all tend to be control freaks.  (Not &lt;em&gt;necessarily&lt;/em&gt; in every area of our lives, but certainly in the cockpit, we tend to have &quot;take charge&quot; personalities.  If something isn't right, we want to make it right, and a &lt;em&gt;laissez faire&lt;/em&gt; &quot;eh, whatever&quot; attitude doesn't tend to be found among pilots at work.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the things that most concern us at a more visceral level, I'll suggest, tend to be the things that we can NOT control.  If an engine catches fire, I'm confident I can put it out with the procedures and tools that I have, and I can get the aircraft back on the ground because I'm trained to do that even with one less engine than usual.  But if there is a raging fire someplace that I can't control (electrical wires -- &lt;a href=&quot;http://en.wikipedia.org/wiki/Swissair_Flight_111&quot; rel=&quot;noreferrer&quot;&gt;SwissAir Flight 111&lt;/a&gt; or cargo hold -- &lt;a href=&quot;http://en.wikipedia.org/wiki/ValuJet_Flight_592&quot; rel=&quot;noreferrer&quot;&gt;ValueJet Flight 592&lt;/a&gt;), then that bothers me.  Similarly, Terry's scenario of cargo loading done wrong -- outside my control, and the pilots have to trust that somebody else did their job correctly.  And by the nature of that being entirely outside my control, that tends to be more of a troubling scenario than any of the typical list of things that I can control and have been trained for: engine fire, depressurization, electrical issues, etc.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-05-12T21:08:52.683" LastActivityDate="2015-05-12T21:08:52.683" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14696" PostTypeId="1" CreationDate="2015-05-12T22:59:25.523" Score="8" ViewCount="1687" Body="&lt;p&gt;How does the A320 (or other Airbus FBW aircraft, for that matter) decide which radio altimeter reading to use (say, for FMGC functions like autothrust), or whether to reject the radio altimeter data altogether and throw an ECAM to the pilots?  It's certainly not a full voting system, considering that the A320 only has two radio altimeters, not three...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(For the curious: I ask because the flight profile from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_Canada_Flight_624&quot; rel=&quot;noreferrer&quot;&gt;ACA 624&lt;/a&gt; mishap bears some resemblance to what would happen if the power rolled back on very short final without the crew noticing.)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2021-03-18T14:18:25.537" Title="How does the A320 FMGC (autothrust, autopilot) decide which radio altimeter readings to use?" Tags="&lt;flight-instruments&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14697" PostTypeId="1" CreationDate="2015-05-13T04:47:32.193" Score="7" ViewCount="1432" Body="&lt;p&gt;How do engineers calculate the hypothetical max altitude of a helicopter if the mass, altitude and length/curvature of blades are known?&lt;/p&gt;&#xA;" OwnerUserId="8453" LastEditorUserId="65" LastEditDate="2015-05-13T13:24:19.590" LastActivityDate="2019-08-09T14:23:32.143" Title="How is hypothetical max altitude of a helicopter calculated?" Tags="&lt;helicopter&gt;&lt;altitude&gt;&lt;performance-calculation&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14698" PostTypeId="1" CreationDate="2015-05-13T04:58:31.340" Score="0" ViewCount="980" Body="&lt;p&gt;How come it is safe and legal to land in parallel runways (for example, in SFO).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The planes are way too close, at a distance that would not, I assume, be according to flight regulations and safety rules during cruise flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what distance from airport or below what altitude becomes it ok to fly like this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can airplanes also take off in parallel, or only land?&lt;/p&gt;&#xA;" OwnerUserId="8454" LastEditorUserId="7532" LastEditDate="2015-05-13T09:05:31.157" LastActivityDate="2015-05-13T09:05:31.157" Title="How is it safe and legal to land in parallel runways" Tags="&lt;safety&gt;&lt;landing&gt;&lt;sfo&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-05-13T08:57:58.230" ContentLicense="CC BY-SA 3.0" />
  <row Id="14699" PostTypeId="2" ParentId="14698" CreationDate="2015-05-13T06:12:04.080" Score="2" Body="&lt;p&gt;Whether &lt;a href=&quot;http://www.skybrary.aero/index.php/Parallel_Runway_Operation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Parallel Runway Operations&lt;/a&gt; are allowed at an airport is dependent on many factors, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/13827/572&quot;&gt;Proximity of runways to each other&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0504.html#?F8258ROBE&quot; rel=&quot;nofollow noreferrer&quot;&gt;Availability of precision approach systems for each runway&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is two modes that are interesting here, which is the full &lt;strong&gt;parallel mode&lt;/strong&gt;, where lateral separation is no longer required once both aircraft are established in the precision approach and &lt;strong&gt;staggered mode&lt;/strong&gt;, where the runways are too close for parallel mode and need to maintain 2.5 NM lateral separation during the approach phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same regulations apply to departures, you can read about it in &lt;a href=&quot;http://www.skybrary.aero/index.php/Parallel_Runway_Operation&quot; rel=&quot;nofollow noreferrer&quot;&gt;EUROCONTROL's SkyBrary&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related questions:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/9361/572&quot;&gt;How are go-arounds safe with parallel runways?&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-13T06:12:04.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14702" PostTypeId="1" CreationDate="2015-05-13T12:39:20.493" Score="14" ViewCount="9671" Body="&lt;p&gt;I initially phrased this question in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/14690/what-is-n1-and-n2#comment34100_14690&quot;&gt;comment&lt;/a&gt; to &lt;a href=&quot;https://aviation.stackexchange.com/q/14690/6919&quot;&gt;another question&lt;/a&gt; regarding what N1 and N2 mean, hoping it would be that sort of low-hanging fruit that is easily answerable and not worth a proper question in its own right.  But then I starting searching and came up short.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20120503144402AAitiwf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This Yahoo Answers page&lt;/a&gt; has lots of guesses on it, from &quot;nominal&quot; to &quot;Newell&quot;.  (And we all now are reminded why nobody goes to that site for real answers.)  Many other pages explain what N1 and N2 are, but not where the &quot;N&quot; part comes from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering if it might have its origin in German, as a lot of early developmental work on jet engines was done in Germany.  Or was it simply an unused letter that fit?&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-14T10:31:40.600" Title="Regarding N1 and N2, what does the &quot;N&quot; stand for?" Tags="&lt;jet-engine&gt;&lt;terminology&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14703" PostTypeId="2" ParentId="14702" CreationDate="2015-05-13T12:44:01.843" Score="1" Body="&lt;p&gt;Here at &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/33480/&quot; rel=&quot;nofollow&quot;&gt;Tech ops&lt;/a&gt;, they say it comes from specific speed.&#xA;However, it does not explain why the letter N was chosen, but perhaps this knowledge might help lead to an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mcnallyinstitute.com/07-html/7-03.html&quot; rel=&quot;nofollow&quot;&gt;This source&lt;/a&gt; mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N is the symbol for &quot;specific speed&quot;. Specific speed is defined as &quot;the speed of an ideal pump geometrically similar to the actual pump, which when running at this speed will raise a unit of volume, in a unit of time through a unit of head&quot;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-05-13T13:48:28.800" LastActivityDate="2015-05-13T13:48:28.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14704" PostTypeId="2" ParentId="14660" CreationDate="2015-05-13T13:49:32.677" Score="7" Body="&lt;p&gt;Yes, as per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1113&quot; rel=&quot;noreferrer&quot;&gt;61.113&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Except as provided in paragraphs (b) through (h) of this section,&#xA;  no person who holds a private pilot certificate &lt;strong&gt;may act as pilot in&#xA;  command of an aircraft that is carrying passengers or property for&#xA;  compensation or hire&lt;/strong&gt;; nor may that person, for compensation or hire,&#xA;  act as pilot in command of an aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A person taxiing an aircraft that is not intended for flight is not acting as PIC under this rule, and therefore can not only be a private pilot, but the person doesn't have to be a pilot at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no specific FAR that qualifies someone to taxi an aircraft, but aircraft operators and maintenance shops train and authorize mechanics to taxi and run-up engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some individual airports have regulations that specify who may taxi and run-up an engine, &lt;a href=&quot;http://www.qcode.us/codes/palmsprings/view.php?topic=16-16_32-16_32_055&quot; rel=&quot;noreferrer&quot;&gt;such as Palm Springs&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a)      Only qualified persons shall start and/or operate an Aircraft&#xA;  engine at the Airport and/or taxi an Aircraft on the Airport.&#xA;  Qualified persons include a pilot, an airframe and power plant&#xA;  mechanic, or a qualified technician licensed by the FAA and qualified&#xA;  to start or operate the engine(s) and/or taxi that particular type and&#xA;  class of Aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;a href=&quot;https://www.municode.com/library/wa/whitman_county/codes/code_of_ordinances?nodeId=TIT14AI_CH14.20GRTARU_14.20.130WHMATAAI&quot; rel=&quot;noreferrer&quot;&gt;Whitman County Airport&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;14.20.130 - Who may taxi aircraft.  No person other than a mechanic, pilot, or properly authorized student pilot, certified by the FAA,&#xA;  shall taxi aircraft on any part of the airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-05-13T19:21:53.923" LastActivityDate="2015-05-13T19:21:53.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14705" PostTypeId="1" AcceptedAnswerId="14708" CreationDate="2015-05-13T14:25:31.833" Score="19" ViewCount="6159" Body="&lt;p&gt;With the exception of the Panavia Tornado, fighters do not have thrust reversers. Why is this? Why does the Panavia Tornado have them?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="1696" LastEditDate="2018-04-24T14:08:31.313" LastActivityDate="2021-01-02T11:03:13.900" Title="Why don't most fighters have thrust reversers?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;jet&gt;&lt;thrust-reverser&gt;&lt;panavia-tornado&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14706" PostTypeId="2" ParentId="14705" CreationDate="2015-05-13T15:03:49.267" Score="10" Body="&lt;p&gt;Fighter aircraft are specialized tools optimized for a specific purpose: to destroy enemy forces (in the air and on the ground).  Everything that is not vital to that mission is quite literally dead weight that reduces the performance of the aircraft as it relates to its specific purpose.  Jet fighters are not required to &quot;taxi back&quot; on the tarmac, and simpler &quot;speed brakes&quot; are more effective at slowing down in flight.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="8346" LastEditDate="2015-05-13T15:45:02.963" LastActivityDate="2015-05-13T15:45:02.963" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="14707" PostTypeId="2" ParentId="14702" CreationDate="2015-05-13T15:09:33.150" Score="0" Body="&lt;p&gt;For rotational speed, $n$ is a common symbol. While the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rotational_speed&quot; rel=&quot;nofollow noreferrer&quot;&gt;English Wikipedia article&lt;/a&gt; uses $\omega_{cyc}$, I can find many English-language sites using the symbol. To be honest, $\omega_{cyc}$ is a really combersome symbol for something that is used as often as rotational speed is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In German (see the &lt;a href=&quot;https://de.wikipedia.org/wiki/Drehzahl&quot; rel=&quot;nofollow noreferrer&quot;&gt;corresponding Wikipedia article&lt;/a&gt;), it is definitely the standard way of representing rotational speed in revolutions per time unit (as already mentioned by &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;Peter Kämpf&lt;/a&gt; above). The origin of this is probably harder to determine, but I imagine that it has something to do with the number of revolutions always being a natural number. After all, $n$ is the go-to symbol for any unit-free integer value in engineering and physics, in my experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usage of the capital letter, which is inconsistent with this, is a little more dubious in my opinion. But I have a theory for that, too: The majority of all software working with the value has, for the last 50 years, probably been written in Fortran. Fortran variable names are, by convention, capitalized. So anyone working with the value or displaying it might have just adopted the name of the variable as the symbol for N1 and N2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any pre-Fortran occurence of the terms might disprove that theory.&lt;/p&gt;&#xA;" OwnerUserId="5665" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-14T07:43:34.303" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14708" PostTypeId="2" ParentId="14705" CreationDate="2015-05-13T15:12:16.260" Score="21" Body="&lt;p&gt;Thrust reversal is a complex system (equals money) and it uses significant amount of fuel (also equals money). It is not a very efficient means to reduce the speed of a landing aircraft either, and other methods (e.g. brakes or &lt;a href=&quot;http://en.wikipedia.org/wiki/Drogue_parachute&quot;&gt;drogue parachutes&lt;/a&gt;) are much better suited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest advantage of thrust reversal is that it cancels out the idle forward thrust working against the aircraft. Canceling out idle thrust isn't an issue on most fighters, as they have an engine nozzle that is open at ground idle to prevent any thrust from being produced. This nozzle probably also makes it a bit difficult to integrate Thrust reversals, but the &lt;a href=&quot;http://en.wikipedia.org/wiki/Panavia_Tornado&quot;&gt;Panavia Tornado&lt;/a&gt; proves it can be done.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-13T15:12:16.260" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14709" PostTypeId="1" CreationDate="2015-05-13T16:03:58.053" Score="1" ViewCount="156" Body="&lt;p&gt;The ailerons of the A380 seem to be in 2 pieces. What is its purpose?&lt;img src=&quot;https://i.stack.imgur.com/XPVUh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="8346" LastEditDate="2015-05-13T16:05:50.037" LastActivityDate="2015-05-13T16:05:50.037" Title="What type of aileron is the AIrbus A380 equipped with?" Tags="&lt;airbus-a380&gt;&lt;ailerons&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-05-13T16:16:35.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="14710" PostTypeId="1" CreationDate="2015-05-13T16:17:54.170" Score="12" ViewCount="3261" Body="&lt;p&gt;What is a ramjet? Was it used on the SR-71 Blackbird?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DfmoJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="22726" LastEditDate="2018-07-21T02:17:09.410" LastActivityDate="2018-07-21T16:14:57.563" Title="What is a ramjet?" Tags="&lt;engine&gt;&lt;supersonic&gt;&lt;sr-71&gt;&lt;ramjet&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14711" PostTypeId="2" ParentId="14710" CreationDate="2015-05-13T16:20:22.613" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ramjet&quot; rel=&quot;nofollow&quot;&gt;Take a look here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but the short answer&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A ramjet, sometimes referred to as a flying stovepipe or an athodyd (an abbreviation of aero thermodynamic duct), is a form of airbreathing jet engine that uses the engine's forward motion to compress incoming air without an axial compressor.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words it uses the thrust it generates to compress the on coming air by &quot;ramming&quot; it into the engine. Since they have no way of drawing air in they do not work in a static (not forward moving) situation. They often work best at supersonic speeds. Aside form the device used to pump fuel into the engine they essentially have no moving parts. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-13T16:24:32.450" LastActivityDate="2015-05-13T16:24:32.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14714" PostTypeId="2" ParentId="14710" CreationDate="2015-05-13T19:34:08.737" Score="6" Body="&lt;p&gt;The ramjet is conceptually the simplest jet engine. It is a duct where air is burned creating a hot jet that provides thrust, it is known aero thermodynamic &lt;strong&gt;duct&lt;/strong&gt; as it is no more than a duct where a thermodynamic cycle is performed. &#xA;They are no more used for airplanes, as &lt;strong&gt;it can not provide thrust at zero airspeed&lt;/strong&gt; -since he does not have any compressor within the diffuser- and modern turbofan is much more efficient. &#xA;It is composed by a &lt;strong&gt;diffuser&lt;/strong&gt; , a &lt;strong&gt;burner&lt;/strong&gt; and a &lt;strong&gt;nozzle&lt;/strong&gt; , it uses dynamic compression of ram air within its inlet and then the hot jet expand in a convergent-divergent nozzle as it is supersonic. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Airplanes like the Blackbird used a ramjet to reach higher mach speed by starting the ramjet when the where already subsonic.&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="8399" LastEditDate="2015-05-14T13:16:30.863" LastActivityDate="2015-05-14T13:16:30.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14715" PostTypeId="1" AcceptedAnswerId="14716" CreationDate="2015-05-13T19:42:29.960" Score="9" ViewCount="1190" Body="&lt;p&gt;What do I have to do to obtain a Canadian pilot's license if I already have an FAA one?&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="62" LastEditDate="2015-05-14T00:52:34.223" LastActivityDate="2017-08-30T17:41:24.420" Title="How can I convert an FAA pilot's certificate to a Canadian one?" Tags="&lt;faa&gt;&lt;pilot-certification&gt;&lt;canada&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14716" PostTypeId="2" ParentId="14715" CreationDate="2015-05-13T19:54:54.393" Score="9" Body="&lt;p&gt;Transport Canada has all the information &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/managementservices-referencecentre-acs-400-401-001-478.htm&quot;&gt;here&lt;/a&gt; for each FAA license type (and type ratings); the necessary forms and contacts are &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/general-personnel-usconversion-1806.htm&quot;&gt;here&lt;/a&gt;. These are the basic requirements for a private pilot, for example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;6.1 Conditions for Conversion - Private Pilot – Aeroplane.&lt;/strong&gt;      &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Must hold an FAA Private airman certificate with airplane category and&#xA;  class rating(s).   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) &lt;strong&gt;Age&lt;/strong&gt;: Must be at least 17 years of age.&lt;br&gt;&#xA;  (2)&#xA;  &lt;strong&gt;Medical fitness&lt;/strong&gt;: Must hold either a Category 1 or Category 3 TCCA&#xA;  medical.&lt;br&gt;&#xA;  (3) &lt;strong&gt;Knowledge&lt;/strong&gt;: Must pass the Conversion - Private Pilot&#xA;  Licence – Aeroplane, (FAAPA) written examination on air laws and&#xA;  communications. Must be able to read, write and communicate in English&#xA;  or French.&lt;br&gt;&#xA;  (4) &lt;strong&gt;Experience&lt;/strong&gt;: Must provide proof of a minimum of 45&#xA;  hours pilot flight time.&lt;br&gt;&#xA;  (5) &lt;strong&gt;Skill&lt;/strong&gt;: No additional practical flight&#xA;  test is required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-13T19:54:54.393" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14717" PostTypeId="2" ParentId="14710" CreationDate="2015-05-13T21:31:37.463" Score="19" Body="&lt;p&gt;A jet engine compresses air, heats it by mixing it with fuel and burns it, and lets the heated air escape at the end, where it accelerates to more than its initial speed in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use/9666#9666&quot;&gt;convergent-divergent&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/13522/can-a-convergent-nozzle-be-used-for-a-supersonic-jet-engine/13719#13719&quot;&gt;nozzle&lt;/a&gt; because the density of the heated gas is lower, thus needing a higher volume at the same pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By converting the kinetic energy of the flow into pressure (potential energy), the intake creates high-pressure air to feed the engine. This is called pressure recovery and increases with the square of flow speed. Please see below for a plot: This puts a pressure of 1 at Mach 0.5, which is on the high side for flow speed near the compressor face in a jet engine intake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dtaIi.png&quot; alt=&quot;pressure recovery ratio over Mach number&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in static conditions the air needs to be accelerated, so the intake pressure is only 84% of ambient pressure, and at Mach 0.85, the maximum speed of airliners, the intake pressure is 1.37 times higher than ambient pressure. But at supersonic speed things take really off: Pressure recovery for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; was already 6 at Mach 2.0, and for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;noreferrer&quot;&gt;SR-71&lt;/a&gt; it was 40 at Mach 3.2. If you want a more mathematical approach, the equation for &lt;a href=&quot;http://en.wikipedia.org/wiki/Isentropic_process&quot; rel=&quot;noreferrer&quot;&gt;isentropic&lt;/a&gt; compression gives: $$p_0 = p_{\infty}\cdot\frac{(1.2\cdot Ma^2)^{3.5}}{\left(1+\frac{5}{6}\cdot(Ma^2-1)\right)^{2.5}}$$&#xA;The odd exponents have to do with the ratio of &lt;a href=&quot;http://en.wikipedia.org/wiki/Heat_capacity&quot; rel=&quot;noreferrer&quot;&gt;specific heats&lt;/a&gt; $\kappa$ of air. 3.5 is actually $\frac{\kappa}{\kappa-1}$ and 2.5 is $\frac{1}{\kappa-1}$. Real compression ratios are slightly below those of the ideal isentropic compression due to friction, but not by much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exact equation used for the plot above is produced by calculating the ratio to the intake Mach number directly, this time with $\kappa$ = 1.405:$$\frac{p_{intake}}{p_{\infty}} = \left(0.2025\cdot Ma^2 \cdot\left(1-\left(\frac{Ma_{intake}}{Ma_{\infty}}\right)^2\right) + 1\right)^{3.469}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, you get already the compression ratio of a &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_J47&quot; rel=&quot;noreferrer&quot;&gt;J-47&lt;/a&gt;, an early turbojet engine, at Mach 2 and that of a &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;noreferrer&quot;&gt;GE90&lt;/a&gt;, a modern turbofan engine, at Mach 3.2. Beyond that, it does not make much sense to complicate the engine with turbo machinery - just let the ram pressure give you the compression for thrust generation. You need, however, speed up the vehicle by other means first, because the possible thrust is proportional to the pressure recovery, or the square of airspeed. No speed, no thrust!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might have read claims that the J-58 of the SR-71 was a ramjet. &lt;a href=&quot;https://www.youtube.com/watch?v=F3ao5SCedIk&quot; rel=&quot;noreferrer&quot;&gt;This is only half true&lt;/a&gt;. Below Mach 2 it worked as a regular turbojet, but it had bypass tubes which ducted some air from the fourth stage of the compressor around the later compressor stages, the combustion chambers and the turbine directly into the afterburner. Now some of the air was compressed in the intake and fed directly to a combustion area and through a convergent-divergent nozzle, so this part worked like a ramjet. Some of the air, however, was still passing through the core engine to keep it running, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A better example for a ramjet-powered plane is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_D-21&quot; rel=&quot;noreferrer&quot;&gt;Lockheed D-21&lt;/a&gt; reconnaissance drone, which used a Marquardt RJ-43 ram jet for propulsion. Its cruise speed was Mach 3.7, back 50 years ago! See below for a picture (&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Lockheed_D-21B_USAF.jpg#/media/File:Lockheed_D-21B_USAF.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/74Ig8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/74Ig8.jpg&quot; alt=&quot;Lockheed D-21 in static display on trolley&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the same trick which makes a ramjet possible can be used to reduce cooling drag for high-speed piston aircraft. A well-designed cooling duct is slowing and compressing incoming air and heats it by letting it flow through a radiator. The heated air has a higher exit speed, resulting in jet thrust which can compensate cooling drag at higher speeds. The &lt;a href=&quot;http://www.militaryfactory.com/aircraft/detail-page-2.asp?aircraft_id=681&quot; rel=&quot;noreferrer&quot;&gt;Republic XF-12&lt;/a&gt;, a much underappreciated design, made exemplary use of this technique.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-06-10T16:09:13.247" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14718" PostTypeId="2" ParentId="14702" CreationDate="2015-05-14T06:47:38.397" Score="4" Body="&lt;p&gt;As far as I can tell, the &lt;strong&gt;N&lt;/strong&gt; comes from the physics behind turbines in general, whether they be water pumps or wind turbines, a subset of mathematics called &lt;a href=&quot;http://en.wikipedia.org/wiki/Fluid_dynamics&quot; rel=&quot;nofollow noreferrer&quot;&gt;fluid dynamics&lt;/a&gt;.  Many thanks to &lt;a href=&quot;https://aviation.stackexchange.com/a/14703/6919&quot;&gt;ROIMaison's answer&lt;/a&gt; for steering me in the right direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;em&gt;Turbomachinery: Basic Theory and Applications, Second Edition&lt;/em&gt;, Earl Logan, Jr. provides a symbol reference list at the end of each chapter starting in chapter 2, defining $N$ as &lt;strong&gt;rotor speed&lt;/strong&gt;, in units of rad/s; an &lt;em&gt;angular&lt;/em&gt; change per unit time, and $N_s$ as the &lt;strong&gt;specific speed&lt;/strong&gt;, a dimension-less quantity derived from a ratio of the flow and head coefficients.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://books.google.com/books?id=s4Qfa1AWGGkC&amp;amp;printsec=frontcover&amp;amp;dq=principles+of+turbomachinery&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=2TNUVca9NcGLNsKTgdgP&amp;amp;ved=0CEwQ6AEwBg#v=onepage&amp;amp;q=rotor%20speed&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3cyvv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;N1 and N2 seem to be derived from both.  Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbreathing_jet_engine#Terminology&quot; rel=&quot;nofollow noreferrer&quot;&gt;mentions&lt;/a&gt; the &lt;em&gt;speed as a percentage&lt;/em&gt; paradigm as a human factors consideration, though as of 5/14/2015 there are no references to support this.  However, there may be a scientific basis behind this as well, since a change in N is proportional to the resultant change in airflow (i.e. thrust produced):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fWKL1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-14T10:31:40.600" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14719" PostTypeId="1" CreationDate="2015-05-14T07:26:34.077" Score="16" ViewCount="12941" Body="&lt;p&gt;I've noticed that the wings of the 787 and A380 tend to flex a lot. Does wing flex help an aircraft in any way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5676V.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="15311" LastEditDate="2020-03-07T20:21:13.840" LastActivityDate="2020-03-07T20:21:13.840" Title="Is wing flex good?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;wing-flex&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14720" PostTypeId="2" ParentId="14719" CreationDate="2015-05-14T07:48:48.050" Score="25" Body="&lt;p&gt;The wings of the Boeing 787 are so flexible because its carbon fiber material can be stretched more, and the high aspect ratio of 11 will magnify this effect. In flight the consequences are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less shaking due to gusts, because the wing will dampen load changes more effectively.&lt;/li&gt;&#xA;&lt;li&gt;Delayed aileron response, because the lift change due to aileron deflection will first bend the wing before it starts to roll the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On the ground one consequence is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing might have less tip clearance, because less in-built dihedral is needed - the rest is supplied by the wing's elasticity in flight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, wing flex is like the suspension in a car. It costs a &lt;a href=&quot;https://aviation.stackexchange.com/questions/838/what-are-the-effects-of-the-boeing-787s-very-flexible-wings&quot;&gt;little bit of performance&lt;/a&gt; but gives a much smoother ride.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-14T07:48:48.050" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14721" PostTypeId="1" CreationDate="2015-05-14T08:02:46.963" Score="6" ViewCount="2199" Body="&lt;p&gt;If Wikipedia is correct the 60 years old &lt;a href=&quot;http://en.wikipedia.org/wiki/Kuznetsov_NK-12&quot;&gt;NK-12&lt;/a&gt; is more fuel efficient than the &lt;a href=&quot;http://en.wikipedia.org/wiki/Europrop_TP400&quot;&gt;Europrop TP400&lt;/a&gt;, the engine for the Airbus A400M transport aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the NK-12MV a specific fuel consumption of 0.219 kg/kW-hr is given. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TP400 has a specific fuel consumption of 0.238 kg/kW-hr according to Wikipedia. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I interpreting these specifications wrongly?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="19" LastEditDate="2015-05-14T09:23:00.017" LastActivityDate="2015-05-14T10:22:44.163" Title="Why is the 60-year-old NK-12 more fuel efficient than Europrop TP400?" Tags="&lt;engine&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14725" PostTypeId="2" ParentId="14721" CreationDate="2015-05-14T09:18:45.870" Score="3" Body="&lt;h1&gt;Age of design&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It is likely that the design of a newly manufactured NK-12 differs significantly from the original designs produced 60-years ago. So we are not really comparing the TSFC of an original 1950's NK-12.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Speed&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Wikipedia's source for the NK-12 quotes a &quot;TO&quot; figure - presumably TSFC at take-off power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia doesn't identify a source for it's (T)SFC figure for the TP400. The makers of the TP400 don't publish SFC figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TSFC increases with speed. Many published TSFC figures are for cruise speeds.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Props&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I imagine efficiency depends somewhat on application, and this must include propeller design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It might be that there are factors other than fuel-efficiency that affect propeller design. For example, noise may not be a factor for most military applications but it would affect civil applications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both these engines were designed for military applications but there may have been some difference in prioritisation of these and other factors.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Conclusion&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I don't think it has been clearly shown that the NK-12 is more efficient than the TP400 (though it may well be).&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-14T10:22:44.163" LastActivityDate="2015-05-14T10:22:44.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14726" PostTypeId="2" ParentId="14721" CreationDate="2015-05-14T09:45:32.240" Score="9" Body="&lt;p&gt;The source of the Specific Fuel Consumption in Wikipedia is unclear. I have found a &lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/Off-Takes/Off-Takes_PUB_AST-CD-Version_13-04-23.pdf&quot;&gt;paper (PDF)&lt;/a&gt; that discusses the efficiency of shaft power off-take (that is using engine power to drive systems such a electric and hydraulic generators instead of delivering propulsion). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It mentions the TP400-D6 (which is installed on the Airbus A400M) has a SFC of 0.167 kg/(kW.h) for shaft power off-take and a SFC of 0.213 kg/(kW.h) for delivering propulsive power. This means that the TP400 is more efficient than the Wikipedia article presents and more efficient than the SFC of the NK-12 presented by Wikipedia. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also shows that the TP400-D6 is more efficient in delivering shaft power than in delivering propulsive power. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-05-14T09:45:32.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14727" PostTypeId="1" AcceptedAnswerId="14729" CreationDate="2015-05-14T11:52:50.293" Score="40" ViewCount="26088" Body="&lt;p&gt;If an aircraft stalls, there are stall warning systems called as Stall computers. Anyone has idea how they predict that its a stall and how they raise the alarm/warning?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5694" LastEditDate="2015-05-14T12:32:53.070" LastActivityDate="2019-03-28T18:03:19.427" Title="How do aircraft stall warning systems work?" Tags="&lt;aircraft-systems&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14728" PostTypeId="2" ParentId="14719" CreationDate="2015-05-14T12:32:41.620" Score="4" Body="&lt;p&gt;I will try to add over @PeterKampf answer. Flexibility is finally another parameter, when you make your design allowing your airplane to be flexible, you are introducing a new variable. As in all optimization problems adding new (smart) parameters allows you to create a more optimized design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just taking the example provided by @PeterKampf , if the airplane is less shaking due to gusts the requirement over the aerodynamics/structure of gust response is more easily achieved. That makes relaxation in some areas of the structure making it lighter. So, altohugh there is a potential cost in aerodynamic performance, it might end in savings in fuel as the airplane will be lighter for the same gust response.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also an effect that is not seen in the picture, what you is the flexion produced by the lift, but also the lift is producing &lt;a href=&quot;http://en.wikipedia.org/wiki/Camber_%28aerodynamics%29&quot; rel=&quot;nofollow&quot;&gt;cambering&lt;/a&gt;, which can be also exploited by the wing to have a more optimized design.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-05-14T12:32:41.620" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14729" PostTypeId="2" ParentId="14727" CreationDate="2015-05-14T12:39:36.377" Score="49" Body="&lt;h2&gt;Audible Warning&lt;/h2&gt;&#xA;&lt;p&gt;On light aircraft there is a reed (much like used on a musical wind instrument) mounted on one wing root, which is angled such that at the Angle of Attack which would cause a stall, the reed &amp;quot;plays&amp;quot; which can be heard in the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;Here is a view of where this system is mounted on a Cessna:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3Gi46.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Gi46.jpg&quot; alt=&quot;stall warner&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.weekendcfii.com/photos/c172preflt/C172_stall_warn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;weekendcfii.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;On some aircraft, it is a similar principle; however instead of a reed, it uses a fin which at critical AoA pushes a micro-switch which activates a buzzer/horn inside the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;Here is the assembly on a Beech 18:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F1B5q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F1B5q.jpg&quot; alt=&quot;stall warner&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.eaa1000.av.org/pix/beech18/stall.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;eaa1000.av.org&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;So, if you ever see anyone doing this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.boldmethod.com/images/pages/about-us/aleks-first-kiss.jpg&quot; alt=&quot;kiss the wing&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;They are not kissing their aircraft for good luck, merely testing the stall warn as part of pre-flight checks!&lt;/p&gt;&#xA;&lt;h2&gt;Tactile Warning&lt;/h2&gt;&#xA;&lt;p&gt;In addition to an audible reed/buzz/horn, most aircraft also provide tactile feedback to the pilot of an impending stall. In purely mechanical aircraft the aerodynamic forces on the control surfaces are transmitted through the mechanisms and are felt directly by the pilot when approaching a stall. In hydraulic or fly-by-wire aircraft, this is provided by a mechanical &amp;quot;stick shaker&amp;quot; linked to the same system as sounding the audible alarm.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-28T18:03:19.427" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="14730" PostTypeId="2" ParentId="14727" CreationDate="2015-05-14T15:56:57.430" Score="32" Body="&lt;p&gt;Large commercial aircraft typically rely on either &lt;a href=&quot;https://aviation.stackexchange.com/questions/2317/how-does-an-alpha-aoa-vane-work&quot;&gt;Angle of Attack (AoA) Vanes&lt;/a&gt; or Differential Pitot Tubes (&lt;a href=&quot;http://utcaerospacesystems.com/cap/systems/sisdocuments/Air%20Data%20Products%20and%20Systems/SmartProbe%20Air%20Data%20Systems.pdf&quot; rel=&quot;noreferrer&quot;&gt;Smart Probes (PDF)&lt;/a&gt;) to supply input to flight computers for the purpose of calculating AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k0NTBm.jpg&quot; alt=&quot;AOA Vane&quot;&gt;&lt;br&gt;&#xA;&lt;strong&gt;&lt;em&gt;AOA Vane&lt;/em&gt;&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the computer(s) calculate an AoA nearing the critical angle, an impending stall is communicated to the pilots. There are visual indications, such as those given on the speed tape and pitch limit indicators (PLI), and tactile indications such as the stick shaker and pusher. Here is &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html&quot; rel=&quot;noreferrer&quot;&gt;a Boeing Article&lt;/a&gt; on AoA measurement (PDF). Figure 11 shows the indications on the primary flight display.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-05-14T17:48:44.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14732" PostTypeId="1" CreationDate="2015-05-14T19:49:04.657" Score="2" ViewCount="466" Body="&lt;p&gt;I am not sure how widely the software is used, but I am using &lt;a href=&quot;http://www.piano.aero/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piano-X&lt;/a&gt; to investigate the influence of total aircraft drag on block fuel consumption and noticed something odd. It is my hope that someone familiar with the software can assist me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I decrease the total aircraft drag both the block time and fuel consumed increases, which is the opposite of what I would expect. As expected however, the block fuel/min does decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shown below is the results from the investigation for the drag systematically decreased :&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ZiGwZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I expect that the block fuel/time would decrease but don't understand how the total time and fuel will increase for decreased drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a rational explanation for this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The software documentation only states the following concerning drag calculation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Aerodynamic drag is calculated in detail (as a function of lift coefficient, Mach number, and Reynolds number) and tuned with actual lift/drag data (‘polars’) whenever these are known. You can either factor the drag uniformly using one overall value or you can adjust certain items individually.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My approach was to vary total drag, i.e. induced and parasite drag simultaneously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will add that the software calculated total block fuel including estimates for both taxi's and the climb-out etc. Now in taxi drag doesn't have an influence, but I doubt that this will make such a large contribution.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="62" LastEditDate="2015-05-15T15:52:56.197" LastActivityDate="2015-05-15T15:52:56.197" Title="What is the influence of drag on an airliner's block fuel consumption?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2015-05-22T13:16:18.933" ContentLicense="CC BY-SA 3.0" />
  <row Id="14733" PostTypeId="2" ParentId="14732" CreationDate="2015-05-14T20:36:41.150" Score="1" Body="&lt;p&gt;I would suspect that reducing drag in this case would be result of reducing airspeed. If your drag coefficient 1 is for a certain speed, slowing down would cause smaller fuel flow but increase flight time and hence increase total consumption.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-05-14T20:36:41.150" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14734" PostTypeId="1" AcceptedAnswerId="27400" CreationDate="2015-05-14T20:49:43.363" Score="12" ViewCount="1506" Body="&lt;p&gt;Are you allowed to fly for profit with SPL? If I have understood correctly, SPL is to LAPL(S) as CPL is to PPL, but with no extra requirements over LAPL(S), but I have problems believing this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming I have understood the rules correctly, I can upgrade my MGPL to LAPL(S)+TMG and therefore to SPL+TMG with no extra effort. After doing the conversion and flying PIC for 75 hours, I would legally be allowed to ask the passengers to pay for my flights. This seems to be too far from the current rulings that I have trouble believing this.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;SPL = Sailplane Pilot License&#xA;LAPL(S) = Lightweight Aircraft Pilot License (Sailplane)&#xA;CPL = Commercial Pilot License&#xA;PPL = Private Pilot License&#xA;TMG = Touring Motor Glider&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="5580" LastEditorUserId="2171" LastEditDate="2015-05-15T02:57:26.000" LastActivityDate="2016-05-06T15:18:02.663" Title="What is allowed with the new EASA SPL license?" Tags="&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14736" PostTypeId="1" AcceptedAnswerId="14737" CreationDate="2015-05-14T23:26:31.103" Score="17" ViewCount="8329" Body="&lt;p&gt;Why would an aircraft perform an unpressurized takeoff? What conditions lead to this being beneficial?&lt;/p&gt;&#xA;" OwnerUserId="8166" LastEditorUserId="65" LastEditDate="2015-05-15T12:00:46.923" LastActivityDate="2019-01-19T03:54:19.927" Title="Why is an unpressurized takeoff performed?" Tags="&lt;takeoff&gt;&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14737" PostTypeId="2" ParentId="14736" CreationDate="2015-05-15T00:29:00.313" Score="25" Body="&lt;p&gt;Typically, the pressurization system is run by engine bleed air. Using that bleed air means you have less engine power available than is maximally available with the bleeds off. If you're on a runway that requires all your power, you do a no-bleeds takeoff, which means you have no pressurization. Shortly after takeoff you would turn the bleeds on.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-05-15T00:29:00.313" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14738" PostTypeId="1" AcceptedAnswerId="14741" CreationDate="2015-05-15T00:58:26.657" Score="2" ViewCount="1290" Body="&lt;p&gt;I have a quick question about wind checks. When I spotting at Sydney (YSSY), I often hear tower clearing aircraft to land and giving them spot wind checks at the runway threshold, all pretty standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I don't understand is when that wind check contains a downwind component.  For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;QFA32, Wind 160/10 Downwind 2, Cleared to land RWY 16R&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(That is an example and not a wind scenario I've heard.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I overthinking this? Is the downwind component just given when they are landing with a tailwind?&lt;/p&gt;&#xA;" OwnerUserId="8476" LastEditorUserId="65" LastEditDate="2015-05-15T12:05:10.897" LastActivityDate="2017-02-12T14:49:30.617" Title="Why is a downwind wind speed given in wind checks for aircraft on final?" Tags="&lt;air-traffic-control&gt;&lt;wind&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14739" PostTypeId="2" ParentId="9450" CreationDate="2015-05-15T05:22:18.053" Score="1" Body="&lt;p&gt;For unaccelerated flight, an aircraft can fly in wings-level zero-sideslip (assuming symmetrical drag/thrust such as asymmetric stores or engine failure) or steady heading sideslip (SHSS). To induce SHSS, the pilot would apply rudder, which in-turn causes sidesplip (Beta). At this point the behaviour of the aircraft is determined by it's inherent aerodynamics as not all behave the same. Just looking at the B2, you will observe that it isn't as 'slab sided' as most commercial or military aircraft might be. Hence there would be less SIDEFORCE than normal aircraft configurations, especially given there is no vertical tail. The effect of this reduction in sideforce means that less angle of bank (lift vector used to counter the sideforce) is required to maintain the SHSS. Now modification of other aircraft configurations such as dihedral and sweep will determine the amount of control that is required to maintain a given SHSS, but doesn't affect the AoB(read sideforce) required due to sideslip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the objective in crosswind is to land within the landing gear side load limits. We need to align the aircraft longitudinal axis as close as possible to the runway direction, but we also must have minimal sideways(lateral) velocity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a typical crosswind approach, The aircraft will fly a crabbed profile in a wings-level zero heading sideslip for the majority of the profile as this is the most efficient in terms of drag reduction. How the pilot controls the aircraft close to the flare depends on the geometry, control power and handling qualities of the aircraft. This will also determine its crosswind limits. There are two options, land in a SHSS or kick-off drift (KoD), or a combination of both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, if geometry is limited (ie large wings, engine pods etc) then you're only option is to kick-off-drift (KoD) while trying to keep the wings and close to level as possible. This would be done at the very last moment as the resultant sideforce created by sideslip will make the aircraft drift laterally away from the runway axes, which if left unchecked, might overcome the structural limits of the gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If geometry isn't limited but handling qualities are an issue, then the option to use SHSS (wing down) in the flare may be valid. This manoeuvre can be easier to perform in some cases as it is less dynamic in the late stage of the flare whereupon you might encounter other delayed secondary effects seen in KoD such as roll due to sideslip - swept wing aircraft especially. Coming back to aircraft that have low sideforce due to sideslip, we might expect this manoeuvre to be even easier to perform as only small amounts of side slip are required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, The handling qualities of the aircraft will depend on how the flight controls are implemented and the stability characteristics of the aircraft. This will determine the best techniques to land the aircraft.       &lt;/p&gt;&#xA;" OwnerUserId="8030" LastEditorUserId="8030" LastEditDate="2017-08-03T21:04:00.173" LastActivityDate="2017-08-03T21:04:00.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14740" PostTypeId="1" AcceptedAnswerId="14750" CreationDate="2015-05-15T05:34:24.933" Score="2" ViewCount="496" Body="&lt;p&gt;During the testing phase of aircraft wings, there are lot of testing like temperature, pressure, humidity, vibration and load/stress. Apart from these, does any one have idea which other tests are done on them for complete qualifications like like lightning?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="8730" LastEditDate="2016-01-31T21:26:26.417" LastActivityDate="2016-01-31T21:26:26.417" Title="What tests are done on aircraft wings for testing the effects of lightning?" Tags="&lt;faa-regulations&gt;&lt;aircraft-development&gt;&lt;lightning&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2015-05-18T13:28:00.917" ContentLicense="CC BY-SA 3.0" />
  <row Id="14741" PostTypeId="2" ParentId="14738" CreationDate="2015-05-15T08:33:38.600" Score="4" Body="&lt;p&gt;'Downwind' speed does indeed mean that the aircraft will be landing with a slight tailwind. Each aircraft/airline has a maximum downwind component which is acceptable to land with - generally about 5-10 knots. From my experiences as a private pilot in Australia, I have observed that ATC will tell the flight crew the current downwind component without being requested to do so. I find that they will also advise if the crosswind component is more than about 5-10 knots. It has been a few months since I last heard it but I believe the wording is along the lines of &quot;Qantas 32 heavy, wind 210 at 7, &lt;strong&gt;maximum downwind&lt;/strong&gt; 7 knots, runway 01 cleared to land&quot;. This information is also available on the ATIS. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2015-05-15T13:50:12.317" LastActivityDate="2015-05-15T13:50:12.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14742" PostTypeId="5" CreationDate="2015-05-15T09:12:28.890" Score="0" Body="&lt;p&gt;The objective of the WINGS — Pilot Proficiency Program is to reduce the&#xA;number of accidents in General Aviation (GA) by assisting airmen to find educational opportunities designed to help them apply the principles of risk assessment and risk management (RM). When properly applied, these principles will help mitigate accident causal factors associated with common pilot errors, lack of proficiency, and faulty knowledge. The Federal Aviation Administration’s (FAA) purpose is to encourage the majority of GA pilots, through WINGS, to engage in ongoing, targeted flying tasks and learning activities keyed to  identified risks and which are designed to mitigate those risks. The FAA continually collects and assesses its databases to identify the risks associated with GA flying and incorporates risk mitigation strategies into initial and ongoing pilot education. &lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-15T09:12:28.890" LastActivityDate="2015-05-15T09:12:28.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14743" PostTypeId="4" CreationDate="2015-05-15T09:12:28.890" Score="0" Body="The US FAA's Pilot Proficiency Award Program (Wings) promotes air safety and encourages general aviation pilots to continue training and maintain proficiency. All of this in an effort to prevent aircraft accidents. " OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-15T09:12:28.890" LastActivityDate="2015-05-15T09:12:28.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14744" PostTypeId="2" ParentId="14736" CreationDate="2015-05-15T11:29:47.273" Score="3" Body="&lt;p&gt;Packs off doesn't mean that the cabin is unpressurized. The outflow valve(s) are closed and the cabin pressure remains steady at aerodrome level.&#xA;This will give better engine thrust as mentioned above.&#xA;Unpressurized cabin would mean outflow valve in open position and cabin pressure would be equal to ambient pressure. This is not allowed on commercial flights (at least JAA/EASA regulations).&#xA;I flew one ferry flight unpressurized and almost popped my ears on takeoff because of the high climb rate.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-05-15T11:29:47.273" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14745" PostTypeId="1" AcceptedAnswerId="14746" CreationDate="2015-05-15T12:05:18.067" Score="6" ViewCount="2309" Body="&lt;p&gt;The stick shakers warns the pilot of stall conditions and some fixed winged aircraft have a stick pusher which tries to avoid the stall. What is the working methodology of stick pushers?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5517" LastEditDate="2015-05-15T12:24:12.580" LastActivityDate="2015-05-15T20:23:14.067" Title="How does the stick pusher prevent an aircraft from stalling?" Tags="&lt;stick-pusher&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14746" PostTypeId="2" ParentId="14745" CreationDate="2015-05-15T12:49:45.357" Score="7" Body="&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Stick_pusher&quot;&gt;simple explanation&lt;/a&gt; is that a stick pusher is a:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... device that pushes forward on the elevator control system&#xA;  whenever the aircraft’s angle of attack reaches the pre-determined&#xA;  value, and then ceases to push when the angle of attack falls&#xA;  sufficiently.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.skybrary.aero/index.php/Stick_Pusher&quot;&gt;detailed explanation&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A stick pusher system incorporates both a passive monitoring component&#xA;  and an active intervention component that consists of an hydraulic or&#xA;  electro-mechanical pusher mechanism. The monitoring component&#xA;  constantly evaluates critical flight parameters such as airspeed, load&#xA;  factor and flap setting against the aircraft angle of attack. If the&#xA;  angle of attack reaches a predetermined value, the intervention&#xA;  component of the system is activated and pushes forward on the&#xA;  elevator control system until the angle of attack is reduced to an&#xA;  acceptable value. The system operates autonomously and without any&#xA;  required action by the pilots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA has an &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1020244&quot;&gt;advisory circular (AC)&lt;/a&gt; for stick pusher training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Embraer 145, &lt;a href=&quot;https://youtu.be/5GrwODV68R8&quot;&gt;this video&lt;/a&gt; shows a demo of stick shaker, stick pusher and the warning systems.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-15T12:49:45.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14747" PostTypeId="2" ParentId="14745" CreationDate="2015-05-15T13:01:59.410" Score="4" Body="&lt;p&gt;To elaborate a bit on what the other answers say we must discuss what a stall is and how it happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off &lt;strong&gt;&lt;em&gt;a stall can happen at any speed or bank angle&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A stall by definition: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...is a reduction in the lift coefficient generated by a foil as angle of attack increases (see picture for what happens to the air when you stall)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ruuVj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and by definition a stall &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...occurs when the critical angle of attack of the foil is exceeded&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So in an aircraft the typical way to recover from a stall is to pitch the aircraft down. This helps to gain speed but mainly reduces the angle of attack of the wing (the angle you exceeded the limit of to stall in the first place) which in turn helps the wing regain proper air flow over it and begin to generate lift again. Thus a stick pusher servers to automate this function of pushing the stick forward (pitching the plane down) to recover from the stall. This can also help in situations where its difficult to know if the plane has stalled much like the accident that occurred on &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air France 447&lt;/a&gt;   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-15T13:01:59.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14748" PostTypeId="5" CreationDate="2015-05-15T13:26:22.490" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow&quot;&gt;Lockheed SR-71 Blackbird&lt;/a&gt; was a US Air Force supersonic reconnaissance aircraft in operation from 1968 to 1999. It was capable of speeds in excess of Mach 3. It has held the world record for the fastest air-breathing manned aircraft since 1976.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="11423" LastEditDate="2015-10-01T01:51:47.970" LastActivityDate="2015-10-01T01:51:47.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14749" PostTypeId="4" CreationDate="2015-05-15T13:26:22.490" Score="0" Body="The Lockheed SR-71 Blackbird was a US Air Force supersonic reconnaissance aircraft." OwnerUserId="62" LastEditorUserId="11423" LastEditDate="2015-10-01T01:51:51.953" LastActivityDate="2015-10-01T01:51:51.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14750" PostTypeId="2" ParentId="14740" CreationDate="2015-05-15T14:43:57.170" Score="2" Body="&lt;p&gt;Almost all the tests done on aircraft wings can easily be categorized in one of the areas you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;The only remaining thing I can think is bending an aircraft's wing. It is &lt;a href=&quot;http://www.bbc.com/future/story/20140319-stress-tests-for-safer-planes&quot; rel=&quot;nofollow noreferrer&quot;&gt;stated on BBC&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Many modern passenger jets can flex their wings nearly 90 degrees in a test rig.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For B787, &lt;a href=&quot;http://www.wired.com/2010/03/boeing-787-passes-incredible-wing-flex-test/&quot; rel=&quot;nofollow noreferrer&quot;&gt;it is reported&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During the test, the wings on the 787 were flexed upward&#xA;  “approximately 25 feet” which equates to 150 percent of the most&#xA;  extreme forces the airplane is ever expected to encounter during&#xA;  normal operation. The test is used to demonstrate a safety margin for&#xA;  the design and is part of the certification process to show the&#xA;  airplane can withstand extreme forces.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/sA9Kato1CxA&quot; rel=&quot;nofollow noreferrer&quot;&gt;This video shows&lt;/a&gt; (also &lt;a href=&quot;https://youtu.be/Ai2HmvAXcU0&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;) how much force a wing can take before breaking.&lt;/strike&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OP &lt;a href=&quot;https://aviation.stackexchange.com/questions/14740/what-tests-are-done-on-aircraft-wings-apart-from-temperature-pressure-humidity#comment34253_14750&quot;&gt;asked&lt;/a&gt; about tests for lightning effects. Lightning commonly strikes the nose, wingtips, engine cowlings, and tip of the vertical tail. Hence, wings are not the only parts of an airplane which needs to be &lt;em&gt;protected&lt;/em&gt; against lightning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To avoid reinventing the wheel, please see the following questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/3836/65&quot;&gt;How is an on ground lightning strike test conducted?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/888/65&quot;&gt;What happens when an airplane gets struck by lightning?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-15T19:02:21.597" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14751" PostTypeId="1" AcceptedAnswerId="14753" CreationDate="2015-05-15T17:57:49.913" Score="22" ViewCount="966" Body="&lt;p&gt;When I fill my tank at a gas station, I can see fuel vapor coming out of the tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine the space above the aircraft tank has fuel vapor mixing with air (at lower oxygen than normal thanks to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Inerting_system&quot; rel=&quot;noreferrer&quot;&gt;inerting system&lt;/a&gt;). During refueling, the fuel will replace the space used by this fuel-air mixture and force the mixture out of the tank. If unmanaged, this is a big fuel source and fire hazard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How is this mixture managed in order to minimize risk of fire or explosion?&lt;/strong&gt; &lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="3825" LastEditDate="2015-05-17T23:08:22.023" LastActivityDate="2017-08-19T19:06:14.533" Title="How is fuel vapor dealt with at large airports?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14752" PostTypeId="1" CreationDate="2015-05-15T18:48:58.123" Score="1" ViewCount="722" Body="&lt;p&gt;The CFM 56-7BE (on the 737) has a long and narrow nozzle, the RR Trent 900 (on the A380) has a sharper nozzle, and the CF-6 (on the 767) has a wider opening at the nozzle. Why do the nozzle sizes vary among turbofans?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-15T19:19:49.387" Title="Why do turbofans have different nozzles?" Tags="&lt;jet-engine&gt;&lt;boeing-737&gt;&lt;airbus-a380&gt;&lt;boeing-767&gt;&lt;turbofan&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14753" PostTypeId="2" ParentId="14751" CreationDate="2015-05-15T19:09:38.590" Score="17" Body="&lt;p&gt;Large airplanes are &lt;a href=&quot;https://aviation.stackexchange.com/a/14765/679&quot;&gt;pressure refuelled&lt;/a&gt; so vapor escaping through the fuel port is not an issue as it is in smaller airplanes.  You are correct, however, that the fuel/air mixture existing in the tank will be displaced by the incoming fuel.  The wings will have vents installed that will allow the air mixture in the tank to escape (and fuel in the case of over fuelling or excess expansion of the fuel after it is loaded).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fire risk is minimized in three ways I can think of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The airplane is grounded to the fuel truck, minimizing the risk of ignition via sparking.&lt;/li&gt;&#xA;&lt;li&gt;The wing vents have flame arrestors so that if the air mixture leaving the wing did ignite, the flame would not make it into the tank.&lt;/li&gt;&#xA;&lt;li&gt;Atmospheric dispersion -- once the air mixture is out of the tank it will become more dilute with time.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the cases there is more than vapor released, e.g. liquid fuel is expelled, these spills will be absorbed to minimize fire risk.  In the ultimate case of fire the fuel truck has fire extinguishers and there is a fire station on the airport that can apply foam and water as needed. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="679" LastEditDate="2017-08-19T19:06:14.533" LastActivityDate="2017-08-19T19:06:14.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14754" PostTypeId="2" ParentId="14752" CreationDate="2015-05-15T19:11:32.020" Score="2" Body="&lt;p&gt;The nozzle, apart from its main function, that is accelerating the air in order to propel the vehicle, it determines what goes into the front of the engine, it is a downstream restrictor along with the turbine nozzle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The areas of both the propelling nozzle and turbine nozzle set the mass flow through the engine and maximum pressure. For different engine operational purposes, it is used one shape or another. These engines have different shapes due to optimization reasons; the engine, is designed in such a way that the aircraft features will have the best balance in terms of fuel consumption, thrust needed, and many other parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each manufacturer design their engines in the most convenient way and then, it is determined which engine is better for a given aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different kind of geometries, (e.g. convergent-divergent) also affect on the engine operation regime (supersonic, subsonic, transonic), but this does not affect here since all the engines are turbofans and thus, subsonic.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="8407" LastEditDate="2015-05-15T19:19:49.387" LastActivityDate="2015-05-15T19:19:49.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14755" PostTypeId="1" CreationDate="2015-05-15T19:34:41.603" Score="6" ViewCount="496" Body="&lt;p&gt;I'm working on some marketing for a regional FBO and while I'm an aviation aficionado, I'm neither a pilot or deeply involved in the aviation industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd love your input on how you research and choose an FBO while doing your flight planning…&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;As a pilot what are your primary considerations when choosing an FBO? Fuel cost, amenities, local knowledge, other things entirely?&lt;/li&gt;&#xA;&lt;li&gt;What things do you look at as distinguishing factors between competitors?&lt;/li&gt;&#xA;&lt;li&gt;Are there certain things that you consider mandatory from an FBO?&lt;/li&gt;&#xA;&lt;li&gt;What information do you want to &quot;know before you go&quot;?&lt;/li&gt;&#xA;&lt;li&gt;What online resources do you personally use when doing your flight planning and/or researching FBO's?&lt;/li&gt;&#xA;&lt;li&gt;Have you had an extremely positive (or terrible) experience with an FBO, so that I can research them?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'll also note that this particular FBO is located in a fairly rural, yet growing region of the Western United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look forward to your input and responses!&lt;/p&gt;&#xA;" OwnerUserId="8486" LastActivityDate="2015-05-18T13:55:37.237" Title="What things do you consider when choosing a fixed base operator (FBO)?" Tags="&lt;fbo&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-05-19T05:14:03.013" ContentLicense="CC BY-SA 3.0" />
  <row Id="14756" PostTypeId="2" ParentId="14755" CreationDate="2015-05-15T20:22:09.763" Score="5" Body="&lt;p&gt;I'll throw in my 2 cents here but I am by no means super experienced in this realm.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Amenities is not a huge deal for me. Generally I fly to go somewhere, while a nice interior is always a bonus, I'm fine as long as there is a bathroom and a receptionist to pay. Generally I'm at the airport to tie up and then leave and go about my business. Some place to sit to wait for weather to improve is nice but I by no means care if the couch is leather or 1970's velour as long as I can sit on it for a while. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I flight plan with ForeFlight.com so I won't comment on what you should have but in today's day and age I would consider a WiFi connection in the FBO a must have since lots of people use tablet based planning now. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel cost is always a consideration and you should try and remain competitive to your local areas as much as possible. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The key for me is a well laid out and clear website that lists prices for what ever you offer and other important information. Maybe an airport map with the location of the FBO clearly marked. A phone number to call for questions is also important.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A solid relationship with a local taxi service is a bonus and a courtesy or rental car would be even better, but I understand how this could be a runaway cost on some level. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Local knowledge is good if there are specific things that may be odd about the airspace and major airport issues that may arise.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-05-18T13:55:37.237" LastActivityDate="2015-05-18T13:55:37.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14757" PostTypeId="2" ParentId="14745" CreationDate="2015-05-15T20:23:14.067" Score="2" Body="&lt;p&gt;Regarding methodology here's how Douglas does it on the MD80. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The stick pusher operates only with slats at mid or extend. It comes on 6 seconds after lights and horn or when AOA increases 4°. If auto slat has failed, stall lights and horn are 0.2 seconds after stick shaker, and the 6 second to override request only 2.5° of AOA for stick pusher.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vd1My.jpg&quot; alt=&quot;Stick Pusher Schematic&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-05-15T20:23:14.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14759" PostTypeId="1" AcceptedAnswerId="14808" CreationDate="2015-05-16T04:50:12.367" Score="20" ViewCount="4805" Body="&lt;p&gt;I've always heard euphemisms about pilots having sex with flight attendants or passengers while flying, but I'm wondering, does this ever happen on commercial flights or in general aviation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have there been incidents of sex in the cockpit when the participants got caught or their actions lead to something more disastrous (like a crash) wherein the truth about their actions was clearly exposed?&lt;/p&gt;&#xA;" OwnerUserId="8166" LastEditorUserId="6" LastEditDate="2015-05-18T12:16:45.273" LastActivityDate="2015-05-18T14:06:48.500" Title="Does sex occur in aircraft cockpits, and is this safe?" Tags="&lt;cockpit&gt;&lt;incidents&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14760" PostTypeId="2" ParentId="14759" CreationDate="2015-05-16T05:19:01.800" Score="8" Body="&lt;p&gt;Does it happen? Unlikely. The cockpit is a rather cramped environment with lots of sharp edges, knobs and switches sticking out, wouldn't be a lot of space for sexual encounters...&lt;br/&gt;&#xA;Also, crews are usually rather busy. Flight crew during the phases before and after cruise, cabin crew during cruise.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;I'd not be surprised if there's the occasional romantic encounter in the crew rest areas of large aircraft on intercontinental flights but I'm pretty sure those involved will keep it quiet as it's no doubt a violation of company policy and could get those involved fired if they brag about it.&lt;br/&gt;&#xA;Far better to wait until you're on the ground in a crew hotel...&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;And even then, the promiscuity of airline staff is almost certainly way less than rumour would have it. These are not adolescent college kids on spring break, they're professionals on a tiring job where they can't drink and need regulation rest hours to be ready and fresh for the return trip the next day.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-05-16T05:19:01.800" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14761" PostTypeId="2" ParentId="9955" CreationDate="2015-05-16T07:11:20.403" Score="1" Body="&lt;p&gt;A stagnation point in a flow does not defy the conservation of mass law. Peter Kämpf already explained that it is an idealization which helps to understand flow phenomena. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that the velocity is zero at a point along a stream line does not mean that mass is collected at that point. You can compare it to a stop sign on a road. Cars arrive at the sign, stop and pull up again. As long as there is sufficient space between successive cars this can be a continuous process representing a steady flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking this analogy further, the stagnation point at the leading edge of a 2D profile is like a T junction on a one way road. Cars arriving at the T junction stop and continue with either a left or right turn and follow thier paths. Air molecules arrive at the stagnation point and continue from there either along the top or the bottom of the profile.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-05-16T07:11:20.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14764" PostTypeId="1" AcceptedAnswerId="14765" CreationDate="2015-05-16T13:10:07.170" Score="16" ViewCount="9047" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/14753/5517&quot;&gt;this answer&lt;/a&gt; to &lt;a href=&quot;https://aviation.stackexchange.com/questions/14751/how-fuel-vapor-is-dealt-with-at-large-airport&quot;&gt;this question&lt;/a&gt;, &quot;pressure refueling&quot; was given as a reason to not worry about fuel vapors escaping when refueling larger aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is pressure refueling and how does it work?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2017-11-03T21:34:47.013" Title="What is pressure refuelling and how does it work?" Tags="&lt;refueling&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14765" PostTypeId="2" ParentId="14764" CreationDate="2015-05-16T13:42:31.530" Score="11" Body="&lt;p&gt;With a pressure fueling system, rather than fueling through holes in the tops of the wings, a fuel truck or fuel hydrant is used to push fuel into the airplane through a fitting at about 50 psi. The fuel fitting is generally in the right wing. A fueling control panel allows the fueler to fill the tanks to the amount called out by the flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These large aircraft still have an overwing fueling port for those times when the pressure fueling system is inoperative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is nothing to prevent fuel vapors from escaping to atmosphere.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/p4epD.png&quot; alt=&quot;Fuel Control Panel&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/SYToK.png&quot; alt=&quot;Fuel Fitting&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/7xcyL.png&quot; alt=&quot;Fuel Tank Arrangement&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/B7Ba8.png&quot; alt=&quot;Fuel Tank Layout&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/SVnRA.png&quot; alt=&quot;Fuel Tank Plumbing&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-05-19T15:30:04.190" LastActivityDate="2015-05-19T15:30:04.190" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14766" PostTypeId="2" ParentId="753" CreationDate="2015-05-16T13:57:18.037" Score="3" Body="&lt;p&gt;Yes they will spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They appear to have enough rudder authority - big twins have a lot, for engine-out reasons, but I don't know the aerodynamics well enough to state that it's certain to be enough, good question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, they have not been spun during test or for training. No, type-ratings don't include spin recovery, just stall recovery in simulators (including FBW types which have to be degraded first to allow them to stall) and recently recovery from unusual attitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simulators can't generally be used to train anything involving sustained yaw because the physical limitations make it impossible to accurately reproduce the feel. They are not built or approved to model accurately anything outside the approval requirement, which doesn't include spins, so while my large aircraft type's sim spins quite nicely ( I do it quite often, for fun, 'after hours' there's no guarantee, proof or reason to expect that the real aircraft would spin in the same way or be as recoverable. &lt;/p&gt;&#xA;" OwnerUserId="8494" LastEditorUserId="3386" LastEditDate="2015-05-16T14:09:02.503" LastActivityDate="2015-05-16T14:09:02.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14767" PostTypeId="1" CreationDate="2015-05-16T14:20:59.467" Score="10" ViewCount="2253" Body="&lt;p&gt;If all winglets serve the same purpose (to reduce vortex drag), why do different aircraft have different winglets? This question is not trying to get a comparison of the development of winglets/wingtips, with other aircraft components, as the question of &lt;a href=&quot;https://aviation.stackexchange.com/questions/8544/is-wingtip-design-mature/%22@Manu%20H%22&quot;&gt;@Manu H&lt;/a&gt; is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nh20a.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-05-17T17:21:47.770" Title="Why are there different types of winglets?" Tags="&lt;aircraft-design&gt;&lt;drag&gt;&lt;winglets&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ClosedDate="2015-05-18T15:17:44.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="14768" PostTypeId="1" AcceptedAnswerId="14769" CreationDate="2015-05-16T14:37:01.287" Score="11" ViewCount="3138" Body="&lt;p&gt;On which part of the landing process does the pilot begin to flare?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vcKNt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="3386" LastEditDate="2017-10-03T04:04:31.873" LastActivityDate="2017-10-03T04:04:31.873" Title="On which part of the descent does a pilot begin to flare?" Tags="&lt;landing&gt;&lt;pilot-technique&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14769" PostTypeId="2" ParentId="14768" CreationDate="2015-05-16T15:02:11.213" Score="13" Body="&lt;p&gt;Flare height is typically 10 ~ 30 feet, which varies with airplane size. At this point, the aircraft has already crossed the runway threshold and is above the runway. Usually, you will smoothly reduce throttle to idle as you cross the threshold (if you don't, the aircraft might climb away!), then flare. That's around 3 to 10 seconds before touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a small GA aircraft, typically you flare when you're around 1 to 2 stories high. The speed will bleed off as you flare, the stall warning might sound ...... which is alright, because you would only stall 2 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a large airliner, flare happens a bit higher. The cockpit of a 747 or A380 is also much higher above the ground (imagine stacking two cargo containers on a trailer, then drive this on a road), which means flare happens much higher from the pilot's perspective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Learning how to flare is one of the things which cannot be practiced in a simulator, because we need peripheral vision to judge height. I have heard seasoned airliner pilots having a hard time landing small aircraft, because they would always flare too high.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-16T15:02:11.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14770" PostTypeId="1" CreationDate="2015-05-16T15:10:07.827" Score="2" ViewCount="304" Body="&lt;p&gt;I've noticed that there are &lt;a href=&quot;http://www.flyunleaded.com/airports.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;very few airports that serve MOGAS&lt;/a&gt;. If I wanted to start a flying club with a MOGAS powered airplane, but there wasn't an FBO nearby that served MOGAS how would I go about it? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it worth it to an FBO to offer MOGAS?&lt;/li&gt;&#xA;&lt;li&gt;Should I have the FC members supply their own gas with a couple of &lt;a href=&quot;http://www.northerntool.com/shop/tools/product_200584598_200584598?utm_source=CSE&amp;amp;utm_medium=Google&amp;amp;utm_campaign=Fuel%20Transfer%20%2B%20Lubrication%20%3E%20Fuel%20Caddies&amp;amp;utm_content=29578&amp;amp;ci_src=17588969&amp;amp;ci_sku=29578&amp;amp;gclid=CMaSpOvDxsUCFdOQHwodNVYAqg&quot; rel=&quot;nofollow noreferrer&quot;&gt;personal fuel stations&lt;/a&gt; like the one pictured below? (anyone have any experience with this method?)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGNOC.jpg&quot; alt=&quot;Personal Fuel Station&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt; Tried to reword questions to make it less business &amp;amp; more &quot;how-to&quot;.&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="6919" LastEditDate="2015-05-18T06:15:35.867" LastActivityDate="2015-08-03T07:13:45.913" Title="How to supply a flying club with MOGAS?" Tags="&lt;fuel&gt;&lt;refueling&gt;&lt;fbo&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14771" PostTypeId="2" ParentId="14767" CreationDate="2015-05-16T15:19:25.023" Score="6" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;Winglet design&lt;/a&gt; is driven more by &lt;a href=&quot;https://aviation.stackexchange.com/questions/8544/is-wingtip-design-mature/8554#8554&quot;&gt;marketing&lt;/a&gt; than by &lt;a href=&quot;https://aviation.stackexchange.com/questions/4980/why-is-it-rare-for-small-aircraft-to-have-winglets/4986#4986&quot;&gt;engineering&lt;/a&gt;, so every aircraft brand tries to cultivate their own, supposedly better, shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A study by &lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/OPerA/OPerA_PUB_DLRK_12-09-10.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nita and Scholz (PDF!), Chapter 6&lt;/a&gt; gives a good overview over recent winglet studies. A raked tip performs better, and if winglets could point downwards, they also could do better. As they are, they give only 28% to 38% drag reduction of an equivalent span increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GOyH0.jpg&quot; alt=&quot;Raked wingtip of the Boeing 777-300&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Raked wingtip of the Boeing 777-300&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-17T17:21:47.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14772" PostTypeId="1" CreationDate="2015-05-16T17:04:59.067" Score="3" ViewCount="2693" Body="&lt;p&gt;An Airbus A320 has seven computers that control flight surfaces:&#xA;two ELAC, three SEC, two FAC, and two AP (autopilot) computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an separate computer that controls auto thrust, or is this controlled through one of the above?&lt;/p&gt;&#xA;" OwnerUserId="7974" LastEditorUserId="6919" LastEditDate="2015-05-19T00:19:30.383" LastActivityDate="2016-10-20T16:43:14.250" Title="Which computer controls auto thrust on an Airbus A320?" Tags="&lt;aircraft-systems&gt;&lt;airbus-a320&gt;&lt;autothrust&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14773" PostTypeId="1" CreationDate="2015-05-16T17:12:26.513" Score="0" ViewCount="104" Body="&lt;p&gt;I am aware of the fact that the autopilot is engaged after takeoff and disengaged before final approach but I was just wondering whether or not the autopilot is capable of landing or taking off a plane.&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-16T17:12:26.513" Title="Is the autopilot system capable of taking off and landing a plane?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;autopilot&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-05-16T19:59:06.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="14774" PostTypeId="2" ParentId="14768" CreationDate="2015-05-16T18:06:06.330" Score="5" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=7hRuDKazY70&quot; rel=&quot;nofollow&quot;&gt;Here is a nice video&lt;/a&gt; that describes it well for a small airplane, worth a watch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flare is a key part of the landing and &lt;em&gt;flaring too high&lt;/em&gt; can cause the plane to fall and possibly bounce.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;late flare or no flare&lt;/em&gt; can cause the plane to come in flat which can lead to a variety of issue that may or may not include bouncing on the nose wheel and other possibly dangerous situations. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-05-18T15:06:16.270" LastActivityDate="2015-05-18T15:06:16.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14775" PostTypeId="2" ParentId="14772" CreationDate="2015-05-16T18:20:12.407" Score="3" Body="&lt;p&gt;The autothrust functions in the A320 are performed by the Flight Management and Guidance Computers, or FMGCs (what you call autopilot computers -- they indeed handle autopilot duties as well).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-05-16T18:20:12.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14776" PostTypeId="2" ParentId="14768" CreationDate="2015-05-16T19:16:49.473" Score="18" Body="&lt;p&gt;This answer is a bit dated since it applies to 747-100 and -200 aircraft in the 1990s. However, the same principles still apply, and I'm sure the same technique would work now on current 747s. Whether or not anybody uses this protocol now I do not know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We flared the aircraft by the numbers without reference to peripheral vision. The use of outside vision was, of course, critical for runway alignment and any necessary crosswind corrections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We flared with reference to the radar altimeter. If it was a 'talking' altimeter, it would announce the altitude of the main landing gear above the ground in the following increments: 100, 50, 40, 30, 20, 10, with the increments being in feet. If the the radar altimeter was an old non-talker, the flight engineer would read those increments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming down the typical 3 degree glideslope on a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1271/what-is-a-stabilized-approach&quot;&gt;stabilized approach&lt;/a&gt;, the nose would be 5 degrees up, and the fuel flow would be about 5,000 lbs per engine. When you heard the 100 foot call, that served simply as an alert. When you heard the 50 foot, you pulled most of the power and raised the nose 2 more degrees. When you heard the 10 foot call, you pulled the rest of the power while raising the nose an additional one degree, maybe a little more if you had the runway length to try for a real greaser at the risk of floating. Then you just waited. Touch down of the main gear would occur within 1 to 3 seconds. If it didn't occur within that time frame, you were floating and would want to reduce your pitch a degree or so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These 'numbers' would be adjusted if you were making a non-stabilized approach, which we often did back then when conditions permitted because stabilized approaches used more time and fuel. Plus, a non-stabilized approach is more challenging and thus much more fun. As I understand it, they're frowned upon these days even to the point of ops specs requiring a stabilized approach.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-18T03:46:01.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14777" PostTypeId="2" ParentId="12981" CreationDate="2015-05-16T22:43:48.147" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.supercoolprops.com/articles/meredith_effect.php&quot;&gt;Here&lt;/a&gt; they give a calculation for the thrust generated by a Meredith effect cooler. They do this for the P51 Mustang. It is also mentioned that in Aeroplane monthly, May 1999 (not accessible to me), the designer Atwood claims that the Meredith effects cooler generates 300 lbs of force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.supercoolprops.com/articles/meredith_effect.php&quot;&gt;They&lt;/a&gt; perform some calculations based on geometry obtained from  Gruenhagen's &quot;Mustang. The story of the P51 fighter&quot;, 1969. These calculations also lead to number around 300 lbs (it calculates 270 lbs of thrust).&#xA;However, the calculations do not included the effects of the heating of the air whilst passing through the cooler (which is -according to me- a vital component of the way in which these coolers generate thrust).&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-05-16T22:56:33.273" LastActivityDate="2015-05-16T22:56:33.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14778" PostTypeId="1" CreationDate="2015-05-17T05:47:39.497" Score="2" ViewCount="341" Body="&lt;p&gt;Is it true that in the new multi scan weather radars fitted in the A320, low level cumulus clouds are not picked up?&lt;/p&gt;&#xA;" OwnerUserId="8499" LastEditorUserId="1696" LastEditDate="2015-05-17T06:08:04.853" LastActivityDate="2015-05-21T01:00:39.063" Title="Can the new multi scan weather radar on the A320 see low level cumulus?" Tags="&lt;weather&gt;&lt;aircraft-systems&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14779" PostTypeId="1" CreationDate="2015-05-17T10:16:41.973" Score="1" ViewCount="147" Body="&lt;p&gt;I have read that some GPS satellites receive this data. Where is that information recorded? Why would it not be used? Inmarsat covers all but the polar regions, why don't the airlines use that system to transmit and track aircraft location data? I don't think that cost would exclude this, as a crash is hugely expensive, especially counting downstream costs (search and recovery, collateral damage, etc.).&lt;a href=&quot;http://www.inmarsat.com/about-us/our-satellites/our-coverage/&quot; rel=&quot;nofollow&quot;&gt;http://www.inmarsat.com/about-us/our-satellites/our-coverage/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8502" LastEditorUserId="64" LastEditDate="2016-02-02T03:27:32.983" LastActivityDate="2016-02-02T03:27:32.983" Title="Why isn't the last known position of a black box continuously available?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;flight-data-recorder&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-05-17T12:30:18.827" ContentLicense="CC BY-SA 3.0" />
  <row Id="14780" PostTypeId="2" ParentId="12714" CreationDate="2015-05-17T12:39:33.623" Score="1" Body="&lt;p&gt;As a general rule of thumb and without a long drawn out technical explanation of how and why here is a simple answer that my 8 year old son could grasp. In straight and level flight, if you reduce power without altering the Aircraft's attitude the Aircraft will descend, conversely if you increase the Aircraft's power it will climb. Now the same Aircraft without altering its power settings if you alter its attitude by lifting the nose it will slow down hence with the same power settings in you lower the nose the Aircraft will increase its speed. So your rule of thumb is &quot;power equals height&quot; and &quot;attitude equals speed&quot;. Go and take a flying lesson and try it, and you will see what I mean.  &lt;/p&gt;&#xA;" OwnerUserId="8503" LastActivityDate="2015-05-17T12:39:33.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14782" PostTypeId="1" AcceptedAnswerId="14784" CreationDate="2015-05-17T13:49:12.847" Score="9" ViewCount="1250" Body="&lt;p&gt;So, I know nothing about aviation. I'm a student studying maths and computing and I feel like building a high altitude glider controlled by a Raspberry Pi and Arduino as a personal project. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First things first, I'll be launching using a weather balloon or something to reach a given altitude (references to any information on glide ratios as you get to higher altitudes would be much appreciated). Once it's high enough the balloon will be deflated and released, the glider will then be dropped and start its descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume I've control of the glider in the form of waypoints I can plot on a map to be put into the onboard computer beforehand (or from signals sent from a computer). How complex an autopilot would be required to follow a set of coordinates (pre-calculated so they fit the descent pattern) and then release a parachute for a safe landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was thinking of purchasing a basic glider structure as to have the maneuverability from the professionally built wings and stuff, so construction shouldn't be a problem. The main concern is how plausible a project like this would be considering I'll be building the flight computer myself and I know basically nothing about flight control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any other material you have on flight control, flight computers, personal projects like this would also be much appreciated.&lt;/p&gt;&#xA;" OwnerUserId="8504" LastEditorUserId="1467" LastEditDate="2016-05-25T10:36:34.987" LastActivityDate="2016-05-25T10:36:34.987" Title="I'm thinking of building a balloon-launched glider, is this idea plausible?" Tags="&lt;flight-instruments&gt;&lt;glider&gt;&lt;parachute&gt;&lt;balloon&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14783" PostTypeId="1" CreationDate="2015-05-17T14:49:05.890" Score="12" ViewCount="1326" Body="&lt;p&gt;I'm looking for an explanation that preserves technical accuracy while remaining brief. Bonus points for including the double boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try to avoid discussing laminar flow and such.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2015-05-18T01:04:43.550" Title="What is the simplest way to explain a sonic boom that is still technically correct?" Tags="&lt;supersonic&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14784" PostTypeId="2" ParentId="14782" CreationDate="2015-05-17T15:00:59.963" Score="8" Body="&lt;p&gt;This idea is entirely plausible and &lt;a href=&quot;http://www.nasa.gov/centers/dryden/history/pastprojects/Apex/&quot; rel=&quot;nofollow noreferrer&quot;&gt;has been tried before&lt;/a&gt;, and &lt;a href=&quot;http://rcexplorer.se/projects/2013/03/fpv-to-space-and-back/&quot; rel=&quot;nofollow noreferrer&quot;&gt;even successfully&lt;/a&gt;. But I guess you have already read through all the pages which you can find via Google.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several things are to be considered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is really cold up there (see below), and the ascent will take long enough that you need to heat the batteries and to remove grease which will likely freeze solid up there. It would be a shame if the onboard camera cannot document the flight because its battery was too cold.&lt;/li&gt;&#xA;&lt;li&gt;Due to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3343/is-an-atmospheric-geostationary-satellite-feasible-with-current-technology&quot;&gt;low air density&lt;/a&gt;, flight speed will be high, so your sailplane will likely experience flutter if you try to use a regular RC glider. A more sturdy configuration which is less optimized for high glide ratios might serve you better.&lt;/li&gt;&#xA;&lt;li&gt;Winds can be very high at altitude, especially between 10 and 16 km height. You need to factor wind drift into your planning. Try to launch on a calm day (calm all the way up, that is), or the plane might not reach the waypoints.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sCAnJ.gif&quot; alt=&quot;Temperature over altitude chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since lower temperature means a lower &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds number&lt;/a&gt;, viscous effects will be higher at altitude than on the ground. This means that your glider's drag for a given lift will be higher at altitude. How much depends a lot on the choice of &lt;a href=&quot;http://en.wikipedia.org/wiki/Airfoil&quot; rel=&quot;nofollow noreferrer&quot;&gt;wing airfoil&lt;/a&gt;. If you go with an existing model, pick one which flies well over a wide speed range. A reasonable glide ratio for a model at altitude would be between 10 to 15, so it will glide 10 to 15 km for each km of altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum altitude in which subsonic flight is possible depends on the wing loading (&lt;a href=&quot;https://aviation.stackexchange.com/questions/9188/what-determines-the-maximum-altitude-a-plane-can-reach/9227#9227&quot;&gt;among other things&lt;/a&gt;), so try to keep masses down.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-17T15:00:59.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14785" PostTypeId="2" ParentId="12714" CreationDate="2015-05-17T15:29:46.250" Score="3" Body="&lt;p&gt;I do think that you must consider the type of aircraft here! If I'm a hotshot new F-22 pilot with an obnoxious thrust to weight ratio trying to intercept some baddies and I need to quickly reach altitude, you can bet I'm gonna put the nose up and go like a rocket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LEVVR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But really though, it's all about velocity vectors. If you want to go up, then travel up! The engines propel in the direction of the nose. (Unless you are that hotshot F-22 pilot from before). Also consider aircraft have speed limits under certain altitudes, and also consider that ole' Bernoulli is not the only reason airplanes fly, Mr. Newton has something to say about this as well.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastActivityDate="2015-05-17T15:29:46.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14786" PostTypeId="1" CreationDate="2015-05-17T15:37:53.597" Score="19" ViewCount="26490" Body="&lt;p&gt;I've noticed that the 737 has a rather unusual vertical stabilizer, with an extension at the front. Is the 737 the only plane equipped with such a vertical stabilizer, and what is its purpose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/57Tmo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="7172" LastEditDate="2015-05-17T16:59:44.447" LastActivityDate="2015-05-20T22:10:38.950" Title="What is the purpose of a dorsal fin such as on the Boeing 737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;airframe&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14787" PostTypeId="2" ParentId="14786" CreationDate="2015-05-17T15:51:32.163" Score="28" Body="&lt;p&gt;The &quot;extension&quot; at the front is called &quot;dorsal fin&quot;. Its main purpose is to improve directional stability in high side-slip situations (asymmetric flight due to engine failure, crosswind landings, etc). The double-sweep of the leading edge of the vertical stabilizer helps the vertical stabilizer to be effective at a larger range of side-slip angles (high lateral angles of attack).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stabilizer is an airfoil, much like a wing. The amount of lift (or in this case, sideways force) it generates, varies with its angle of attack (AoA, or $\alpha$), or in this case, sideslip-angle ($\beta$) something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WahpB.png&quot; alt=&quot;CL vs AoA&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift coefficient ($C_L$) increases with increased $\alpha$, until it reaches $C_{L_{MAX}}$. This angle is called $\alpha_{crit}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the more sweepback an airfoil has, the lower its $C_{L_{MAX}}$, BUT the higher its $\alpha_{crit}$. This means that the non-dorsal-fin-part of the stabilizer (low sweepback) will be able to generate its $C_{L_{MAX}}$ (sideways lift) at a lower $\beta$ than the dorsal fin. Increasing the side-slip angle beyond its $\beta_{crit}$ decrease the amount of sideways force it generates. By using a secondary airfoil (the dorsal fin), with a higher sweep angle, (ie, higher $\beta_{crit}$), the net loss in sideways force with increased side-slip may be avoided, or at least mitigated. Further, at high $\alpha$, (or in this case, with a vertical stabilizer $\beta$), a delta with high sweepback will generate a vortex, which will follow the upper side of the surface down-stream of it, adding kinetic energy to its airflow, thus enhancing its effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current version of the dorsal fin was added to the Boeing 737 with the Classic (−300 and onwards), but the design is not unique for the Boeing 737. Look the Cessna 172 for instance (Wikimedia Commons): &#xA;&lt;img src=&quot;https://i.stack.imgur.com/HMOAG.jpg&quot; alt=&quot;Cessna 172&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATR 72 doesn't have a &quot;pronounced&quot; dorsal fin, but you can still see clearly how the sweepback of the vertical stabilizer changes along its length (Wikimedia Commons):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/j8rjy.jpg&quot; alt=&quot;ATR 72&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, on the other side of the speed spectrum (Wikimedia Commons):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sR5bY.jpg&quot; alt=&quot;Concorde&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-18T10:11:40.863" LastActivityDate="2015-05-18T10:11:40.863" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14788" PostTypeId="2" ParentId="14783" CreationDate="2015-05-17T15:54:38.193" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.quora.com/Aerodynamics/What-really-happens-during-a-sonic-boom&quot; rel=&quot;nofollow&quot;&gt;Is this what you're looking for&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When an object passes through the air, it creates a series of pressure&#xA;  waves in front of it and behind it, similar to the bow and stern waves&#xA;  created by a boat. These waves travel at the speed of sound, and as&#xA;  the speed of the object increases, the waves are forced together, or&#xA;  compressed, because they cannot &quot;get out of the way&quot; of each other,&#xA;  eventually merging into a single shock wave at the speed of sound. In&#xA;  smooth flight, the shock wave starts at the nose of the aircraft and&#xA;  ends at the tail.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There is a rise in pressure at the nose, decreasing steadily to a&#xA;  negative pressure at the tail, followed by a sudden return to normal&#xA;  pressure after the object passes. This &quot;overpressure profile&quot; is known&#xA;  as an N-wave because of its shape. The &quot;boom&quot; is experienced when&#xA;  there is a sudden change in pressure, so the N-wave causes two booms,&#xA;  one when the initial pressure rise from the nose hits, and another&#xA;  when the tail passes and the pressure suddenly returns to normal. This&#xA;  leads to a distinctive &quot;double boom&quot; from supersonic aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-05-17T15:54:38.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14789" PostTypeId="1" AcceptedAnswerId="14794" CreationDate="2015-05-17T16:27:26.940" Score="15" ViewCount="17062" Body="&lt;p&gt;While an aircraft is airborne, the local barometric pressure can change, causing an altimeter to no longer display the correct altitude. How are altimeters re-calibrated to display the correct altitude, or there are other methods to accomplish that?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="824" LastEditDate="2015-05-17T21:12:48.900" LastActivityDate="2017-10-07T02:13:29.350" Title="How do aircraft altimeters calculate altitudes accurately while airborne?" Tags="&lt;flight-instruments&gt;&lt;altitude&gt;&lt;altimeter&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14790" PostTypeId="2" ParentId="14783" CreationDate="2015-05-17T16:28:32.350" Score="7" Body="&lt;p&gt;I will try to explain the principle, briefly and practically as you requested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine that we have an airplane flying in position 1. It is flying at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0rsdo.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good, now this airplane moves forward. But it is not the only one moving forward, the perturbation that the airplane produces over the air moves as well, but at a different speed, the speed of sound. In the next figure you will see that the perturbation (or pressure wave) moves less distance than the airplane, which moves from 1 to 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CFh6f.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplane keeps moving to position 3, and at position 2 there are some perturbations (pressure waves) that are also generated and also move as speed of sound. However, I have smartly selected a perturbation that reaches exactly the same point in space that the perturbation (pressure wave) that I selected is reaching as well. So both perturbations meet at the same point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yT4Iw.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you imagine these two are not the only perturbations (pressure waves) that are meeting at this point, there are several points between 1 and 3 that also generate perturbations that join. Actually, this is also not the only point in space where perturbations (pressure waves) join together: there is a line that envelopes the points where the pressure waves meet at each instant. Well, actually a surface in 3D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VF7cz.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, if you do the same with a better painting tool than me&amp;hellip; you draw the same but also evolving with time like this:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/bEF0b.gif&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is the image in Wikipedia. What is the effect that you experience?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9ud3V.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the orange observer that is located in advance/before the blue lines does not feel any perturbation due to the airplane, nor hear it, as the pressure wave have not reach him yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the green observer has already felt the airplane passing by and sees how the air is altered by the airplane (imagine that you are close enough).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally the brown observer is just in the middle, coming from a region which has not yet experienced the perturbations made by the airplane and finds suddenly a concentration of perturbations (pressure waves) as described above. That is a sudden change in air flow properties and is experienced as a sonic boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give a real end to this, notice that the further you are from the airplane the less strength the pressure waves have when they arrive at the blue line, making the sonic boom less and less intense.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="4474" LastEditDate="2015-05-18T01:04:43.550" LastActivityDate="2015-05-18T01:04:43.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14791" PostTypeId="2" ParentId="14786" CreationDate="2015-05-17T16:38:42.563" Score="19" Body="&lt;p&gt;The vertical tail stabilizes the aircraft in the yaw axis. The fuselage is unstable, so a stabilizing fin must be added. Since the vertical has a much higher aspect ratio than the fuselage, &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;it will stall first&lt;/a&gt;. Beyond the stall angle of sideslip, the vertical will not be able to overcome the still increasing instability of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To remedy this, a &lt;a href=&quot;https://aviation.stackexchange.com/questions/4994/why-delta-wings-are-not-commonly-used-in-commercial-airliners/5002#5002&quot;&gt;delta wing with high sweep&lt;/a&gt; has been added ahead of the lower part of the vertical. It will not stall but continue to increase its sideload with higher angles of sideslip, thus stabilizing the whole plane in yaw even when the vertical tail itself is stalled. Since the high sweep will produce a vortex at high sideslip, this will also help to make the lower part of the vertical more effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding the fin extension or &lt;a href=&quot;https://aviation.stackexchange.com/questions/11808/why-do-some-airplanes-have-vertical-strakes/11812#11812&quot;&gt;strake&lt;/a&gt; will keep the aircraft stable into higher angles of sideslip.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-17T16:38:42.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14792" PostTypeId="2" ParentId="14789" CreationDate="2015-05-17T16:45:27.863" Score="4" Body="&lt;p&gt;Altimeters are connected to a static pressure port, a little vent that's outside the aircraft. This senses the pressure in the outside air. For the altimeter to update with the correct altitude, it senses differences and changes in air pressure. As an aircraft climbs, the pressure decreases, and the altimeter registers an increase in altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what happens if you're on the ground, and the atmospheric pressure changes over time? You need to calibrate your altimeter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since altimeters are extremely sensitive to air pressure, a slight change can register a big difference. There is normally a knob, which lets you calibrate it. It allows you to adjust the readings in the air pressure, known as Inches of Mercury. Generally, the expectation is that this setting is at 29.92 inches of mercury.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As aircraft move into areas with differences in air pressure, pilots have to adjust the altimeter to account for this. Pilots will normally be notified by the ground when flying at local altitudes, for example during approach or 10 000 AGL. Re-adjusting is simple: just turn the knob. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2aU5U.jpg&quot; alt=&quot;Altimeter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As seen in the picture, you have the altimeter. To the bottom-left is the knob to adjust the readings. The little numbers on the right indicate the current observation in Inches of Mercury. Here, it is &lt;em&gt;29.92&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7670" LastActivityDate="2015-05-17T16:45:27.863" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14793" PostTypeId="1" AcceptedAnswerId="14802" CreationDate="2015-05-17T16:45:39.043" Score="6" ViewCount="356" Body="&lt;p&gt;What would happen if one or more of the blades (but not all) on a variable pitch prop would not tilt at the same angle as the other ones?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could this situation happen or is the technology so advanced or stable that it would be basically impossible?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should it happen, besides vibration (most probably due to imbalance factors,) what other effect could there be? How would pilots solve this emergency (if it can be called so?)&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="167" LastEditDate="2015-05-18T04:04:09.607" LastActivityDate="2016-11-28T13:27:00.800" Title="What would happen if the blades of a variable pitch prop did not all have the same pitch?" Tags="&lt;propeller&gt;&lt;blade&gt;&lt;variable-pitch&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14794" PostTypeId="2" ParentId="14789" CreationDate="2015-05-17T16:47:22.127" Score="25" Body="&lt;p&gt;Altimeters are calibrated to a standard atmosphere model (International Standard Atmosphere, &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Standard_Atmosphere&quot; rel=&quot;nofollow noreferrer&quot;&gt;ISA&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the altimeter shows you is the vertical distance between the altitude equivalent to your current pressure (pressure altitude) and a reference &quot;pressure altitude&quot;. The reference pressure altitude is set in pressure units (hPa or In. Hg) on the altimeter subscale. This is known as the &quot;altimeter setting&quot;, set in the &quot;altimeter setting window&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/POu8U.jpg&quot; alt=&quot;Altimeter&quot;&gt;&lt;br&gt;&#xA;Image credit: &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Pilots Handbook of Aeronautical Knowledge&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying at lower altitudes (below &quot;transition altitude&quot;), the altimeter is set to airport/regional QNH, which is a pressure calculated so that if you were standing on the measurement point, the altimeter would indicate your exact elevation. At other altitudes, it would approximate altitude above mean sea level, although it would show incorrectly if temperature differed from ISA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above transition altitude, the altimeter is set to QNE, or standard pressure (1013.25 hPa, or 29.92 In. Hg). The altimeter will now only indicate correctly if both temperature and pressure are in accordance with ISA. You are now flying on &quot;flight level&quot; (where the FL is your QNE indication in hundreds of feet, &lt;em&gt;ie&lt;/em&gt; 20,000 ft = FL200).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purpose of avoiding obstacles, both QNH and QNE have to be corrected using various methods, which are described in various manuals. (QNH for temperature, QNE for both temperature and pressure, both for other possible factors such as wind etc). For instance, this diagram shows three different aircraft, all flying the same pressure altitude, but with three different true altitudes:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/yoYJQ.png&quot; alt=&quot;Temperature errors&quot;&gt;&lt;br&gt;&#xA;Image credit: &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Pilots Handbook of Aeronautical Knowledge&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However&lt;/strong&gt;, altitude is also used for the purpose of traffic separation, and for this purpose, neither QNH or QNE is corrected. This might sound counter-intuitive, but as long as your altimeter is showing the same error as any conflicting traffic, you can be safely separated, therefore: &lt;strong&gt;The altitude shown on the altimeter is not corrected at all&lt;/strong&gt; (except by calibration for possible aerodynamic interference, such as compressibility, venturi-effects etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In technically sophisticated aircraft, barometric altitude input is used for vertical navigation. Since vertical navigation is concerned with the true altitude of the aircraft, the aircrafts Air Data Computer (ADC) will calculated a true altitude based on information available to it (either through sensors, or through pilot input). The true altitude is however, as stated, not shown on the pilots primary flight instruments. &lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="9825" LastEditDate="2017-10-07T02:13:29.350" LastActivityDate="2017-10-07T02:13:29.350" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14795" PostTypeId="1" AcceptedAnswerId="14798" CreationDate="2015-05-17T16:51:22.717" Score="13" ViewCount="2455" Body="&lt;p&gt;Why is it that on most airliners, when the landing gear gets deployed, you always hear a loud noise like a bang. Is this due to the equipment locking in place or is there some other reason? As an external person I would think that there should be a mechanism that pushes it down slowly, avoiding this noise but it doesn't seem the case.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="8346" LastEditDate="2015-05-17T19:03:49.283" LastActivityDate="2019-03-06T05:48:30.040" Title="What is the cause of the noise heard when the landing gear is deployed?" Tags="&lt;landing-gear&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14796" PostTypeId="2" ParentId="14789" CreationDate="2015-05-17T16:56:53.593" Score="7" Body="&lt;p&gt;There are two separate answers to this question, depending on what altitude the flight is conducted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At lower altitudes, below the transition altitude (18,000' in the US, but it varies from country to country), it is the responsibility of the pilot to receive the local &quot;altimeter setting&quot; -- which is the local barometric pressure, corrected to sea level.  So if you are preparing to takeoff from an airport on the high pressure side of the front, that might be 30.30 inches of mercury, and this value would be set in the altimeter, and at this point the altimeter should display the field elevation for where you are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's say that you fly across the front into an area of much lower barometric pressure -- perhaps 29.80&quot; Hg.  That is now what is set into the altimeter, and upon landing your altimeter will display the altitude of the airport where you've landed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that if you did this all at once, going from 30.30 to 29.80, you'd be dialing in a very large change into your altimeter, which would change the indicated altitude by about 500 feet, meaning that you were that far off of the altitude you thought you were flying, and that's a bad thing.  So what happens in reality is that every few dozen miles, you'd get an updated altimeter setting from any of the various weather reporting facilities available -- ATC, automated ASOS broadcasts, data-linked weather, FSS, etc.  So you'd adjust from 30.30 to 30.25, then later to 30.31, then later to whatever the next station was reporting, and so on -- each a much smaller adjustment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft flying at high altitudes (and high groundspeeds), this process becomes impractical, so a different solution is used.  Passing through the transition altitude, a standard setting of 29.92&quot; Hg is entered into the altimeter, and so now everyone is flying at a constant altitude above NOT mean sea level, but above a reference plane.  And altitude is no longer reported at 15,000', but as Flight Levels -- FL 190 for what would otherwise be called 19,000', etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that FL FL400 isn't really 40,000' above sea level most days, and on some days it's higher than that, and other days it's lower, but as long as everybody assigned to fly at FL400 is at the &lt;em&gt;same&lt;/em&gt; altitude (which they are, all having 29.92 set in their altimeters), everything works.  (Particularly since everybody at FL400 is 1000' above everybody at FL390 -- that's what we &lt;strong&gt;really&lt;/strong&gt; care about!)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-17T16:56:53.593" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14797" PostTypeId="1" AcceptedAnswerId="14799" CreationDate="2015-05-17T17:28:34.000" Score="5" ViewCount="894" Body="&lt;p&gt;While airborne if there needs a change in heading, then what is the rate of change of heading with respect to time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like, I want to change my heading from &lt;em&gt;x&lt;/em&gt; degrees to &lt;em&gt;y&lt;/em&gt; degrees, where the difference is 45 degrees, do we have some specific time limit in which we have to get this change and do we have some regulation/standard for specific rate of heading change?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="167" LastEditDate="2015-05-19T02:39:44.980" LastActivityDate="2015-05-19T18:51:30.913" Title="How quickly should heading changes be accomplished?" Tags="&lt;heading&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14798" PostTypeId="2" ParentId="14795" CreationDate="2015-05-17T17:50:47.597" Score="16" Body="&lt;p&gt;The locks release and typically the gear falls free into place.  It is often aided by hydraulic motors (i.e. to overcome anything that might be trying to hold the gear up, such as slush from the takeoff runway that froze after the gear was in the well), but most landing gear will freefall into place within a couple of seconds even without hydraulic assistance after the uplocks are released.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you're probably hearing is the sudden onset of the wind noise -- when retracted the landing gear is streamlined, but when extended there is now an open cavity where the gear had been, and this open area in the fuselage creates a lot of wind noise from the suddenly turbulent airflow.  Going from a relatively quite state to a loud one suddenly gives the impression of a &quot;bang.&quot;  This is possibly enhanced by whatever noise is made by the uplocks that hold the landing gear in place releasing, and perhaps some louder noise as the initial moments of the gear extension may be noisier than the steady-state noise of being fully extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the noise due to the turbulence will subside as the airspeed slows, and extending the landing gear often comes during a phase of flight when the airspeed is being reduced in preparation for the final approach segment and the subsequent landing.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-17T17:50:47.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14799" PostTypeId="2" ParentId="14797" CreationDate="2015-05-17T18:03:14.293" Score="9" Body="&lt;p&gt;According to Wikipedia, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Standard_rate_turn&quot; rel=&quot;nofollow&quot;&gt;&quot;Standard Rate Turn&quot;&lt;/a&gt; is three degrees of heading change per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bank angle required to achieve this depends on your true airspeed; at a low TAS a standard rate turn is easily achievable with normal, comfortable bank angles (say, 20°, plus or minus).  At high true airspeeds, the bank required becomes excessive, and &quot;half standard rate&quot; is used if anything is used, but at least in airline flying it's not particularly common to use either.  We just reference an angle of bank &amp;mdash; but what that gives you in degrees per second is variable (as a function of TAS again).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The upper limit of what an airliner (or pretty much any IFR aircraft) is going to give the controller in terms of turn rate is whatever you get with a 30° bank.  And if that produces less than standard rate or whatever, then so be it.  At high altitude (say 35,000' and above), even 30° can be on the edge of problematic (mainly, with regard to wing loading and Mach buffet), and controllers are used to rates of turn that are less than what you'd see down low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you're looking for a ballpark, 3 degrees per second at low airspeeds (say, under 200 knots), then 2 degrees per second up to maybe 300 knots, and 1 degree per second above that.  Ballpark, but reasonable numbers.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="4474" LastEditDate="2015-05-19T18:51:30.913" LastActivityDate="2015-05-19T18:51:30.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14800" PostTypeId="1" CreationDate="2015-05-17T18:11:16.047" Score="1" ViewCount="141" Body="&lt;p&gt;I am a bit stuck with my career and just need some advice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am currently a technician at &lt;a href=&quot;http://www.transmaldivian.com/&quot; rel=&quot;nofollow&quot;&gt;Trans Maldivian Airways&lt;/a&gt; (Twin Otter). I would like to work in an airline in the future. Is this organization EASA 147 approved?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what are the necessary steps I should take to get the license? If not what should I do? I did not do any basic training and I am completing modules conducted by SR Techniques. &lt;/p&gt;&#xA;" OwnerUserId="8511" LastEditorUserId="62" LastEditDate="2015-05-18T13:34:07.547" LastActivityDate="2015-05-27T17:04:06.013" Title="Is my company EASA 147 approved? How to get an EASA licence?" Tags="&lt;career&gt;&lt;easa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14801" PostTypeId="1" CreationDate="2015-05-17T18:46:46.280" Score="3" ViewCount="484" Body="&lt;p&gt;Why is speed measured in knots (as opposed to kmp/h or mp/h), and distances in nautical miles? Is there a reason for following such a system?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-18T08:46:56.233" Title="Is there an explanation for the measurement system used in aviation?" Tags="&lt;faa&gt;&lt;measurement&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-05-18T08:57:39.193" ContentLicense="CC BY-SA 3.0" />
  <row Id="14802" PostTypeId="2" ParentId="14793" CreationDate="2015-05-17T18:48:45.543" Score="8" Body="&lt;p&gt;Never say never, but that's not a prop malfunction that I've heard of or that was ever addressed in the turboprops that I've flown.  We had various prop malfunctions, but the ways that things could fail that we considered would pretty much leave all blades in the same place.  So without claiming that it could not, ever, ever, no way no how, not in all possibility ever happen, I'll say that it's not very likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you did get something like that, the vibration would probably be bad enough that you'd shut the engine down, and at that point the interesting question would be, do all the blades feather for you?  (The answer to that probably depends on what type of prop you have and what specific failure mode led to the condition in the first place, and now we're into too much speculation for any answer to be very enlightening.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-17T18:48:45.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14803" PostTypeId="1" AcceptedAnswerId="14805" CreationDate="2015-05-17T18:57:55.210" Score="3" ViewCount="2314" Body="&lt;p&gt;I've noticed that there are saw-teeth on modern jet engines such as the GEnx and the Rolls Royce Trent 1000. What is their purpose? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/a58QS.jpg&quot; alt=&quot;Lufthansa Kisses Chevrons&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="3386" LastEditDate="2017-07-06T21:17:18.810" LastActivityDate="2017-07-06T21:17:18.810" Title="What is the use of saw-teeth present on the nacelle outlets of modern turbofans?" Tags="&lt;jet-engine&gt;&lt;turbofan&gt;&lt;feature-identification&gt;&lt;chevrons&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-05-17T21:28:54.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="14804" PostTypeId="2" ParentId="14803" CreationDate="2015-05-17T19:02:26.027" Score="-3" Body="&lt;p&gt;To quote from the Wikipedia article on the subject:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In aerospace industry, chevrons are the sawtooth patterns on the&#xA;  trailing edges of some jet engine nozzles[1] that are used for noise&#xA;  reduction. Their principle of operation is that, as hot air from the&#xA;  engine core mixes with cooler air blowing through the engine fan, the&#xA;  shaped edges serve to smooth the mixing, which reduces noise-creating&#xA;  turbulence.[1] Chevrons were developed with the help of NASA.[1][2]&#xA;  Some notable examples of such engines include GEnx and Rolls-Royce&#xA;  Trent 1000.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Banke, Jim (2012-12-13). &quot;NASA Helps Create a More Silent Night&quot;. NASA. Retrieved January 12, 2013.&lt;/li&gt;&#xA;&lt;li&gt;Zaman, K.B.M.Q.; Bridges, J. E.; Huff, D. L. (17–21 December 2010). &quot;Evolution from 'Tabs' to 'Chevron Technology’–a Review&quot; (PDF-1.34 MB). Proceedings of the 13th Asian Congress of Fluid Mechanics 17–21 December 2010, Dhaka, Bangladesh (NASA Glenn Research Center. Cleveland, Ohio). Retrieved January 29, 2013.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-05-17T19:02:26.027" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14805" PostTypeId="2" ParentId="14803" CreationDate="2015-05-17T19:05:01.750" Score="8" Body="&lt;p&gt;These &quot;saw-teeth&quot; or &quot;chevrons&quot; or even &quot;acoustic liners&quot;, are there to help reduce noise generated from the operation of the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As hot air from the inner core of the engine mixes with the other, cooler air, it generates noise. These &quot;saw-teeth&quot; are there to help smooth that mixing, thereby generating less noise which is the result of turbulence. These are seen on the Boeing 747-8 (as seen in your picture) and the Boeing 787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reduction of sound generated means that less noise insulation is needed for use in the fuselage of the airplane. Less insulation means less weight. Less-weight equals less fuel burn, which means that chevrons are great for passengers, and economics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's only one difference from your picture. As much as we would like them to blow kisses to everyone, that's not what they are there for. :)&lt;/p&gt;&#xA;" OwnerUserId="7670" LastEditorUserId="7670" LastEditDate="2015-05-17T19:14:45.980" LastActivityDate="2015-05-17T19:14:45.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14806" PostTypeId="2" ParentId="14801" CreationDate="2015-05-17T19:07:03.037" Score="5" Body="&lt;p&gt;To quote from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Knot_%28unit%29&quot; rel=&quot;nofollow&quot;&gt;Wikipedia article&lt;/a&gt; on the subject:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although the unit knot does not fit within the SI system, its&#xA;  retention for nautical and aviation use is important because standard&#xA;  nautical charts are on the Mercator projection and the scale varies&#xA;  with latitude. On a chart of the North Atlantic, the scale varies by a&#xA;  factor of two from Florida to Greenland. A single graphic scale, of&#xA;  the sort on many maps, would therefore be useless on such a chart.&#xA;  Since the length of a nautical mile, for practical purposes, is&#xA;  equivalent to about a minute of latitude, a distance in nautical miles&#xA;  on a chart can easily be measured by using dividers and the latitude&#xA;  scales on the sides of the chart. Recent British Admiralty charts have&#xA;  a latitude scale down the middle to make this even easier.[8]&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;8&quot;&gt;&#xA;  &lt;li&gt;e.g. BA Chart 73, Puerto de Huelva and Approaches, 2002&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-05-18T08:46:56.233" LastActivityDate="2015-05-18T08:46:56.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14807" PostTypeId="2" ParentId="14797" CreationDate="2015-05-17T19:23:00.697" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Turn_and_slip_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turn Indicator&lt;/a&gt; (shown below) has a mark that shows a standard rate turn which takes 2 minutes to go all the way around. The heading indicator (on the right below) can be used to determine how far you have turned or how close you are to your desired heading:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Np3oNm.png&quot; alt=&quot;turn indicator&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3NkV6.jpg&quot; alt=&quot;heading indicator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no &quot;regulations&quot; about turns. A pilot will typically use standard good pilotage skills to make a turn of a type which is needed for the situation. In small planes, the pilots are taught to make crisp, decisive turns to get on course as soon as possible. Large planes with passengers tend to make very gentle turns in order to keep the passengers as level and undisturbed as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that a pilot can make a controlled turn onto a heading with just the turn coordinator. In a standard rate turn you do 3 degrees per second, so if you need to turn, say, 15 degrees, you adopt a standard rate turn and count 5 seconds. This technique can be used to escape after flying accidentally into a violent storm. The pilot makes a standard rate turn (15 degrees) then counts 1 minute (60 seconds). This will cause the plane to reverse direction and hopefully lead out of the storm.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-05-17T19:23:00.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14808" PostTypeId="2" ParentId="14759" CreationDate="2015-05-18T00:42:15.890" Score="30" Body="&lt;p&gt;As jwenting said, it's unlikely to happen for many reasons, and if it does, the participants are even less likely to admit it since doing so could get them in trouble both professionally, and with a government regulatory agency for endangering safety. I seem to remember the FAA taking action against a pilot who posted photographs of himself flying with either naked or bikini clad women at his side, but I can't seem to find a link right now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001212X18632&quot;&gt;NTSB report&lt;/a&gt; which is somewhat famous in the aviation community for describing a general aviation crash which was likely caused by sexual activity. However, the summary is very delicately worded, to say the least:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The private pilot and a pilot rated passenger were going to practice simulated instrument flight. Witnesses observed the airplane's right wing fail in a dive and crash. Examination of the wreckage and bodies revealed that both occupants were partially clothed and the front right seat was in the full aft reclining position. Neither body showed evidence of seatbelts or shoulder harnesses being worn. Examination of the individuals' clothing revealed no evidence of ripping or distress to the zippers and belts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6" LastEditorUserId="65" LastEditDate="2015-05-18T14:06:48.500" LastActivityDate="2015-05-18T14:06:48.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14809" PostTypeId="1" CreationDate="2015-05-18T01:48:03.477" Score="3" ViewCount="583" Body="&lt;p&gt;About a year ago one sailor showed his fancy life jacket. It included EPIRB or also known as personal beacon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To date, the smallest personal beacon I managed to find is Fastnet 220, which weights 150 grams and has battery life of 6 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the scale of airline industry, how much would it cost in installation, maintenance and fuel, to fit each passenger life jacket with such device, excluding the device cost itself?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; Total weight per 200 seat airplane is 30kg. Perhaps someone can translate to fuel/$ per year per whole industry? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Thomas Cook PDF, I found that life jackets are audited every 12 weeks and takes up to 40 man-hours per aircraft although they've implemented RFID tags now. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Regarding points outside the original question scope&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The device cost can also decrease to few dollars if they are manufactured in mass scale. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certification is also a factor. Feel free to estimate it as well if you are familiar with the industry.&lt;/p&gt;&#xA;" OwnerUserId="8514" LastEditorUserId="8514" LastEditDate="2015-05-18T05:58:01.560" LastActivityDate="2015-05-18T19:42:15.130" Title="How much would it cost to fit and maintain every passenger life jacket with personal beacon?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="14811" PostTypeId="1" AcceptedAnswerId="14812" CreationDate="2015-05-18T05:25:13.080" Score="10" ViewCount="3236" Body="&lt;p&gt;I have noticed that many small planes do not have &lt;a href=&quot;https://aviation.stackexchange.com/a/1905&quot;&gt;tillers&lt;/a&gt; like in big aircraft.  So how does the pilot steer them?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-05-18T17:42:49.903" Title="How are small airplanes steered on the ground if they don't have tillers?" Tags="&lt;flight-controls&gt;&lt;taxiing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14812" PostTypeId="2" ParentId="14811" CreationDate="2015-05-18T05:39:59.117" Score="17" Body="&lt;p&gt;Most small planes (there are exceptions!) have three wheels - two fixed wheels, one under each wing, and one under either the nose or the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the third wheel is under the nose (&quot;tricycle&quot; layout), that wheel is usually (but not always) steerable with the same pedals as the rudder, enabling accurate steering on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qLYVQ.jpg&quot; alt=&quot;NoseWheel AvWeb&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.avweb.com/news/features/Flying-The-Nosewheel-223233-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AvWeb&lt;/a&gt; - Author: Joseph Burnside)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rudder itself will also add an element of steering moment depending on the airflow over the fuselage (taxiing speed is usually too low for this to have much effect, except that on single engine aircraft applying power will push air over the fuselage and tail, adding effectiveness to the rudder).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, for sharp turning at low speeds, differential braking can be applied - press the brake pedal for the starboard main wheel only, and the plane will tend to pivot about that wheel - ie turn right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the third wheel is under the tail (&quot;tail-dragger&quot; layout), the tail wheel is not usually steerable (it usually pivots freely - but again there are exceptions!). In this case the other two techniques mentioned above - rudder and differential braking - are the only methods of steering on the ground. I've never flown a taildragger myself but I understand the taxiing technique takes some getting used to. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hKfhz.jpg&quot; alt=&quot;Tailwheel TigerMoth&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Conventional_landing_gear#/media/File:De_Havilland_DH.82_Tiger_Moth_-_undercarriage_tailwheel_detail.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiMedia Commons&lt;/a&gt; - Author: RenioLinossi)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="4162" LastEditorUserId="4162" LastEditDate="2015-05-18T17:42:49.903" LastActivityDate="2015-05-18T17:42:49.903" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="14813" PostTypeId="2" ParentId="14786" CreationDate="2015-05-18T08:25:17.370" Score="0" Body="&lt;p&gt;For planes that fly at high speeds (near or above the speed of sound) that strake helps with &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;nofollow&quot;&gt;area ruling&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the craft nears speed of sound the characteristics of air change and the change in cross sectional area over the longitudinal axis becomes an important factor in drag forces. Keeping this smooth as possible will decrease drag in the transonic regime.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That strake will let the rudder itself be smaller and move more of its volume forward and smooth out the transition to the rudder proper.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-05-18T08:25:17.370" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14814" PostTypeId="1" AcceptedAnswerId="14817" CreationDate="2015-05-18T08:25:49.897" Score="2" ViewCount="11732" Body="&lt;p&gt;I have heard that pilots learn in simulators to fly also commercial planes without working engines, so that they glide. And still I have the impression, the chances that a plane could float from 11000 meters height are nearly 0. Could someone explain, if a commercial plain CAN BE THEORETICALLY (Physics) and PRACTICALLY landed from 11km with all failed engines? How important is the altitude from which all engines fail?&lt;/p&gt;&#xA;" OwnerUserId="8517" LastEditorUserId="8517" LastEditDate="2015-05-20T16:13:06.290" LastActivityDate="2019-11-05T01:10:22.233" Title="Could a commercial plane like Airbus A320 glide with no working engines from 11000 meters?" Tags="&lt;glide-ratio&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ClosedDate="2015-05-18T08:45:54.583" ContentLicense="CC BY-SA 3.0" />
  <row Id="14815" PostTypeId="2" ParentId="14801" CreationDate="2015-05-18T08:31:35.713" Score="1" Body="&lt;p&gt;Knots are a measurement of nautical miles per hour. As long as we are using nautical miles for distance for navigation purposes, it would be silly to use anything other than nautical miles per hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One nautical mile is one minute of latitude. Maps can therefore provide a pretty accurate measurement of distance even at the higher latitudes as long as there is a lat/long scale. If you were using anything but nautical miles as your measurement, you would have to add an extra step in to convert.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, if it 'aint broke, don't fix it. The current system certainly isnt consistent from country to country. But if you were to change things, the likelihood of everyone agreeing to using the metric or imperial system? It's much easier to stick with this neutral measurement. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-05-18T08:31:35.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14816" PostTypeId="2" ParentId="14814" CreationDate="2015-05-18T08:43:09.743" Score="3" Body="&lt;h1&gt;Yes&lt;/h1&gt;&#xA;&lt;p&gt;On &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2499076/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt; a participant named Longhauler posted the following in 2005&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If you wish to maintain the highest altitude, you maintain your best lift drag ratio. For the A320 that's about 220 knots. You will descend about 1500 ft/minute. So from 35000 ft, it will take you roughly 25 minutes to reach the ground. You will travel roughly 90 nm.&lt;/p&gt;&#xA;&lt;p&gt;To travel the furthest distance, you descend at M0.74/270 knots. Again, from 35000 ft, you will travel roughly 95-100 nm.&lt;/p&gt;&#xA;&lt;p&gt;To cover a distance the quickest you descend at M0.80/330, but you be gliding like a simonized crowbar. (namely dropping like a stone). You will travel only about 65 miles, but you'll get there quicker!&lt;/p&gt;&#xA;&lt;p&gt;As someone said above, you have to remember, pretty well all descents are done with the thrust at idle.&lt;/p&gt;&#xA;&lt;p&gt;Another consideration, is that without engines, your cabin will depressurize. Slowly on newer aircraft, increasing with the age of the aircraft. It is a balance with finding a place to land within your gliding range, but also looking at your cabin altitude rising.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;11000 meters is 5.94 nautical miles - so that's easy from cruising altitude.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-18T08:43:09.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14817" PostTypeId="2" ParentId="14814" CreationDate="2015-05-18T08:44:00.357" Score="7" Body="&lt;p&gt;All standard fixed wing aircraft are able to glide. The key measure of performance in gliding is the glide ratio which is related to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lift-to-drag_ratio&quot; rel=&quot;nofollow noreferrer&quot;&gt;lift-to-drag ratio&lt;/a&gt; of the aircraft. The glide ratio of a clean A320 is 17:1 which means it can travel 17 units of distance forwards for every 1 unit of distance downward at best glide speed. Using your figure of 11,000 meters away and multiplying by 17 results in a maximum range of 187km . In practice, the aircraft would need to be higher than this (or land closer) to accomodate turns and other factors, but if the A320 was at 1000 meters AGL or higher I would expect it to have no problem landing at an airfield or airport 11km away. Note that aircraft routinely glide every time you fly even though you may be unaware of it. When a commercial flight begins its descent often power will be brought back to idle, so the aircraft is gliding at that point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been several instances of large commercial aircraft landing fully unpowered. One well known example is the case of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Gimli&quot; glider&lt;/a&gt; in which a Boeing 767 ran out of fuel and glided to landing at a nearby airbase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: It has been brought to my attention that the OP is asking about a starting altitude, not how far away from the airfield. As I imply in my answer what matters is the ratio of altitude and distance, not altitude alone.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2019-11-05T01:10:22.233" LastActivityDate="2019-11-05T01:10:22.233" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="14818" PostTypeId="1" AcceptedAnswerId="14823" CreationDate="2015-05-18T12:05:34.503" Score="20" ViewCount="1605" Body="&lt;p&gt;In modern airliners, do systems like the in-flight entertainment system (IFE) share the same physical and/or logical network as the flight management systems (FMS)? Is there any communication between the IFE and the FMS? Also, is there any Airbus training or procedure that might deal with what to do if flight systems were being tampered with? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking because an information security researcher named Chris Roberts is in &lt;a href=&quot;http://www.theregister.co.uk/2015/05/17/fbi_claims_infosec_bod_took_control_of_united_airlines_plane_midflight/&quot; rel=&quot;nofollow&quot;&gt;a bit of trouble&lt;/a&gt; with the FBI after claiming he hacked into the entertainment systems on Airbus and Boeing airliners and used the access to tamper with the airplanes' flight control systems. Apparently he would connect into a Seat Entertainment Box (SEB) and hack the IFE system. I am an information security professional myself and I have no reason to disbelieve this part given my personal experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I am initially skeptical about is that he has claimed to have successfully tampered with flight control systems using the access gained from the compromised IFE. Specifically listed in &lt;a href=&quot;https://regmedia.co.uk/2015/05/17/fbi_chris_roberts_search_warrant_application.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; he has allegedly claimed that he issued a climb command to one of the engines through the thrust management computer, causing it to spool up and temporarily cause the aircraft to yaw. This would only be possible if the IFE were able to communicate somehow with the FMS.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="774" LastEditDate="2015-05-19T21:58:34.117" LastActivityDate="2015-05-19T21:58:34.117" Title="Are commercial aircraft designed with a shared data network?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;aircraft-systems&gt;&lt;security&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14820" PostTypeId="1" AcceptedAnswerId="14822" CreationDate="2015-05-18T13:50:29.617" Score="25" ViewCount="26512" Body="&lt;p&gt;Why do planes, like the famous XF-11 and the Tu-95, have contra-rotating props? What is their purpose?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/RBmHM.jpg&quot; alt=&quot;Tupolev Tu-95&quot;&gt;&lt;br&gt;&#xA;Image credit: Mike Freer / &lt;a href=&quot;http://www.touchdown-aviation.com/&quot; rel=&quot;noreferrer&quot;&gt;Touchdown-Aviation&lt;/a&gt; / &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Tupolev_Tu-95MS,_Russia_-_Air_Force_AN1064678.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="14897" LastEditDate="2020-02-22T04:53:39.600" LastActivityDate="2020-02-22T07:52:44.930" Title="What is the purpose of having contra-rotating props on an aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;propeller&gt;&lt;turboprop&gt;&lt;contra-rotating&gt;" AnswerCount="8" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14822" PostTypeId="2" ParentId="14820" CreationDate="2015-05-18T14:54:23.803" Score="21" Body="&lt;p&gt;According to my experience, you have two problems with props:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Torque&lt;/li&gt;&#xA;&lt;li&gt;Exhaust Speed&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If you use contra-rotating propellers, you eliminate the torque reaction problem because you now have two contra-rotating propellers each cancelling out the opposite's torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also you increase the speed of air accelerated by the propellers, thus the aircraft’s efficiency at relatively high travelling speeds is increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, the propeller can only be operated effectively at low Mach numbers and increasing the RPM above a certain point will only cause the air behind the propeller to compress but not accelerate. Using a second propeller with higher pitch angles can generate high enough airspeed without the problem of compression because the second propeller is rotating inside the airstream generated by the first propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Correction&#xA;However, having a different speed and pitch WILL induce a torque effect.&lt;/p&gt;&#xA;" OwnerUserId="8521" LastEditorUserId="-1" LastEditDate="2017-07-09T01:04:13.273" LastActivityDate="2017-07-09T01:04:13.273" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14823" PostTypeId="2" ParentId="14818" CreationDate="2015-05-18T15:30:47.850" Score="8" Body="&lt;p&gt;Aircraft do have &lt;a href=&quot;http://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;noreferrer&quot;&gt;LAN Networks&lt;/a&gt; for their sensors to minimize wiring (and consequently weight), however I would assume these are closed circuit networks and NOT connected to the IFE system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of the FMS system on aircraft according to &lt;a href=&quot;http://www.b737.org.uk/fmc.htm&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; they do have databases however I dug into it a bit and it seems that based on &lt;a href=&quot;http://www.rockwellcollins.com/~/media/Files/Unsecure/Products/Product%20Brochures/Navigation%20and%20Guidance/Flight%20Management%20Systems/Database%20Download%20Instructions/Dataloading_Instructions.ashx&quot; rel=&quot;noreferrer&quot;&gt;this walk through on updating&lt;/a&gt; you need to physically connect to the device to change that database (for Rockwell Collins Equipment). It also seems that the Honeywell FMS computers have a similar way of &lt;a href=&quot;http://www.sea-avionics.com/lc/cart.php?target=productDetails&amp;amp;model=DL-950&amp;amp;substring=&quot; rel=&quot;noreferrer&quot;&gt;updating via USB&lt;/a&gt;. While I cant say for certain it does not seem the FMS is on any kind of network aside from its own. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big question is autopilot/FBW systems and can they be overridden or tampered with. It seems that Boeing-Honeywell &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_Uninterruptible_Autopilot&quot; rel=&quot;noreferrer&quot;&gt;has a patent&lt;/a&gt; on some remote flying systems but has not yet implemented it on any aircraft. I am still looking for some solid evidence that the systems have a point of access on the network. It is clear that they can be altered if you can &lt;em&gt;physically connect to them&lt;/em&gt; for update purposes. Keep in mind you would have to load them with false data. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.rockwellcollins.com/Data/Products/Controls/Autopilot/AFDS-770_Autopilot_Flight_Director_System.aspx&quot; rel=&quot;noreferrer&quot;&gt;This seems to be the autopilot for the 777&lt;/a&gt; however Rockwell Collins does not seem to allow you to get the info on it very readily. Maybe someone else on here can comment on how its set up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf&quot; rel=&quot;noreferrer&quot;&gt;This nice paper overview&lt;/a&gt; of FBW systems on a 777, in section 11.4.4 lists the connections the FBW system has to other systems on the plane. While this is by no means an official document (at least I don't think so) it does not list the IFE system as a connection and is pretty clear on the fact that everything connects over the &lt;a href=&quot;http://www.wseas.us/e-library/conferences/2010/Vouliagmeni/CSECS/CSECS-34.pdf&quot; rel=&quot;noreferrer&quot;&gt;ARINC 629&lt;/a&gt; style data busses. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does appear that &lt;a href=&quot;http://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet&quot; rel=&quot;noreferrer&quot;&gt;ethernet technology&lt;/a&gt; is making its way onto aircraft however it seems that the tech still uses ARINC Specification 664. However &lt;a href=&quot;http://www.cems.uwe.ac.uk/~ngunton/afdx_detailed.pdf&quot; rel=&quot;noreferrer&quot;&gt;page 2 of this spec documents&lt;/a&gt; seems to imply that through a &quot;gateway&quot; the system is connected to the &quot;internet&quot;. However Page 38 clearly states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although AFDX/ARINC 664 is a &lt;strong&gt;&lt;em&gt;closed&lt;/em&gt;&lt;/strong&gt; network, UDP port numbers&#xA;  should be selected from the Dynamic/Private range of numbers. The reason&#xA;  for this is that there could be potential conflicts with the standard port&#xA;  number assignments when a gateway is used to communicate between the&#xA;  AFDX network and the Internet&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is connected to the internet but the flight control systems are on a closed network. They also advise you to use the private range of ports to avoid any possible conflicts. &lt;a href=&quot;http://www.cems.uwe.ac.uk/~ngunton/afdx_arinc664.pdf&quot; rel=&quot;noreferrer&quot;&gt;Here is another good paper&lt;/a&gt; on the technology. It does seem that they are moving towards some &lt;em&gt;internet like&lt;/em&gt; devices on aircraft but it also seems that they will remain closed networks. Companies are looking to consume some modern tech for an age old application as its simpler and easier to use existing high speed bus technology than reinvent the wheel and make a new custom bus. Just because something has a router and ethernet cables does not mean its connected to the internet!&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-18T17:25:44.497" LastActivityDate="2015-05-18T17:25:44.497" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14825" PostTypeId="2" ParentId="14820" CreationDate="2015-05-18T15:51:05.327" Score="13" Body="&lt;p&gt;The main advantage of contra-rotating props is the increased efficiency (6 to 16% according to Wikipedia). Another advantage is that the torque is pretty much cancelled out by the contra-rotating prop, but this is much less of an issue in aircraft with an engine configuration like the Tu-95 in your post.&#xA;I would say, another advantage is the fact that this design allows for a smaller propeller diameter, allowing a smaller landing gear, etc etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disadvantages may outweigh the advantages depending on the design. They are very complex. This may lead to high maintenance costs, or an unreliable design. Contra-rotating props are also extremely loud. The Tu-95 is known to be the loudest aircraft in the world. Rumors are that they can actually be heard by submarines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that there aren't many aircraft using this design is proof that it isn't very popular. As far as I know, the only reason the Tu-95 doesn't use regular turbine engines is because there were no turbine engines available that would meet the required specification during the design stage of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2362" LastActivityDate="2015-05-18T15:51:05.327" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14826" PostTypeId="1" CreationDate="2015-05-18T17:58:13.037" Score="15" ViewCount="17549" Body="&lt;p&gt;When ATC says &quot;cleared for takeoff&quot;, what's the correct answer from the pilot?&lt;/p&gt;&#xA;" OwnerUserId="8522" LastEditorUserId="7670" LastEditDate="2015-05-19T01:49:05.480" LastActivityDate="2016-10-17T08:12:02.880" Title="How should a pilot respond verbally to being cleared for takeoff?" Tags="&lt;air-traffic-control&gt;&lt;takeoff&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14827" PostTypeId="2" ParentId="14826" CreationDate="2015-05-18T18:02:50.087" Score="25" Body="&lt;p&gt;This is how &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media/Presentations/12-02-RD179-RNAV_TPP_General_Info_example.pdf&quot;&gt;FAA recommends (PDF)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A typical takeoff clearance may state, for example, “(Callsign) 123&#xA;  RNAV to MPASS, Runway 26L, Cleared for Takeoff”.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The expected pilot response is, “(Callsign) 123, RNAV to MPASS, Runway&#xA;  26L, Cleared for Takeoff”.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-05-18T18:17:56.233" LastActivityDate="2015-05-18T18:17:56.233" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14828" PostTypeId="2" ParentId="14826" CreationDate="2015-05-18T18:05:43.867" Score="21" Body="&lt;p&gt;Same phraseology you're given: &lt;em&gt;cleared for takeoff&lt;/em&gt; with your callsign, and if applicable, the runway or instructions (&quot;turn left heading 200&quot; for instance) given in the same transmission. Anything else is nonstandard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not &lt;em&gt;on the roll&lt;/em&gt; nor &lt;em&gt;on the go&lt;/em&gt; nor &lt;em&gt;cleared for departure&lt;/em&gt; nor anything else, no matter how cool it sounded when somebody else said it on the radio.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="15224" LastEditDate="2016-10-17T08:12:02.880" LastActivityDate="2016-10-17T08:12:02.880" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14829" PostTypeId="1" AcceptedAnswerId="14843" CreationDate="2015-05-18T18:39:47.640" Score="23" ViewCount="3215" Body="&lt;p&gt;What airplane designs have been around the longest, from first flight through last retirement from active commercial or military service?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is that the DC-3 will win, since it has been around since before WW II and is still in service, although there are enough other designs out there I'm not familiar with that I'll be interested to see where I may be wrong on that. (Russian designs come to mind as an obvious source of possibilities.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anything out there beat the DC-3? What's the runner up?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The &lt;a href=&quot;http://en.m.wikipedia.org/wiki/Douglas_DC-3&quot;&gt;wikipedia page on the DC-3&lt;/a&gt; says its first flight was December 17, 1935.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="167" LastEditDate="2015-05-19T02:40:25.190" LastActivityDate="2020-12-16T15:56:54.053" Title="Which airplane designs have the greatest longevity?" Tags="&lt;aircraft-design&gt;&lt;aviation-history&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14830" PostTypeId="2" ParentId="14829" CreationDate="2015-05-18T18:53:44.933" Score="8" Body="&lt;p&gt;The legendary &lt;a href=&quot;http://en.wikipedia.org/wiki/Piper_J-3_Cub&quot;&gt;Piper Cub&lt;/a&gt; which was used as a trainer during WWII and first flew in 1938 is still a popular plane and although not by Piper is still made in some form of variants today. I dont think its in service any more (at least as far as I know) but there are still loads of them flying.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-18T18:53:44.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14831" PostTypeId="2" ParentId="14829" CreationDate="2015-05-18T18:54:47.197" Score="17" Body="&lt;p&gt;If any commercial or military service will do then there are a few designs which are older.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a de Havilland Dragon Rapide still in commercial service doing air tours around London, that's first flight was in 1934. The Noorduyn Norseman is still used for air tours and cargo work and it was first flown a month before the DC3. The Ford Trimotor was introduced in 1925 and I think there's still one or two doing tours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from tours the DC3 is still the one I'd think of as still doing really serious service.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1696" LastEditDate="2015-05-18T18:56:41.377" LastActivityDate="2015-05-18T18:56:41.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14832" PostTypeId="2" ParentId="14809" CreationDate="2015-05-18T19:42:15.130" Score="2" Body="&lt;p&gt;The extra weight is roughly the weight saved by the introduction of iPads to replace paper. That's apparently saving close to $10K per plane, so you'd expect a similar cost for just flying all those beacons around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, why do you need a full beacon for every vest? If your vests end up scattered over even 10 kilometers distance, you won't have survivors. What you need is a few beacons to locate the plane, and the medium-range active RFID tag on each vest. Such a tag only responds to queries originating nearby. This cuts down dramatically on the battery requirements, as the RFID tag is generally asleep and only woken up by the interrogation signal. Such RFID tags would cost about $20, and weigh a few grams. Battery life is similar (6 years) as that's just chemistry.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-05-18T19:42:15.130" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14833" PostTypeId="2" ParentId="14829" CreationDate="2015-05-18T19:44:55.847" Score="14" Body="&lt;p&gt;The &lt;a href=&quot;http://www.shuttleworth.org/the-collection/&quot;&gt;Shuttleworth Collection&lt;/a&gt;, at Old Warden aerodrome in Great Britain, has a flyable &lt;a href=&quot;http://en.wikipedia.org/wiki/Bl%C3%A9riot_XI&quot;&gt;Bleriot XI&lt;/a&gt; which was built in 1909 and served at a flight school into the Thirties. It is still regularly displayed in flight. You might argue that this is no commercial service, but to witness the display, you need to buy a ticket, and ticket sales help to support the collection. So I enter it as a contender here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having flown first in 1932, the Ju-52 is also older than the DC-3 or even the Dragon Rapide. Several are still in commercial service - you can book scheduled sight-seeing flights with the Swiss operator Ju-Air. Ju-Air's three Ju-52 served from 1939 to 1982 in the Swiss Air Force. &lt;a href=&quot;http://en.wikipedia.org/wiki/List_of_airworthy_Ju_52s&quot;&gt;Wikipedia&lt;/a&gt; has an exhaustive list of current Ju-52 operators.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-05-18T20:39:45.540" LastActivityDate="2015-05-18T20:39:45.540" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14834" PostTypeId="1" AcceptedAnswerId="14835" CreationDate="2015-05-18T21:54:23.837" Score="3" ViewCount="1060" Body="&lt;p&gt;What are the requirements like height, weight, sight to pass the medical exam for getting a pilot's license ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any medical conditions that would make someone to fail it?&#xA;I know daltonism would be one of those.&lt;/p&gt;&#xA;" OwnerUserId="8524" LastEditorUserId="167" LastEditDate="2015-05-24T14:11:33.010" LastActivityDate="2018-05-04T23:50:27.430" Title="What are the minimum requirements to pass the FAA medical exam?" Tags="&lt;medical&gt;&lt;faa-approval&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14835" PostTypeId="2" ParentId="14834" CreationDate="2015-05-18T22:10:08.757" Score="3" Body="&lt;p&gt;There are no height or weight requirements as far as I know and you dont need perfect vision. I wear glasses and have a &quot;corrective lens&quot; note on my medical. I think that at minimum your vision needs to be correctable to 20/20. See &lt;a href=&quot;https://www.faa.gov/pilots/become/medical/&quot; rel=&quot;nofollow&quot;&gt;this link&lt;/a&gt; for some information as well as the &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/&quot; rel=&quot;nofollow&quot;&gt;information for doctors here&lt;/a&gt;. You can also get special dispensation for certain medical conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a small side note, if you are asking this in relation to a Private Pilot License, they may be doing away with the current third class medical regulations which will ease the regulations greatly. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-18T22:10:08.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14837" PostTypeId="5" CreationDate="2015-05-19T00:25:11.503" Score="0" Body="&lt;p&gt;The company is notable for having produced the L-29 Delfin, L-39 Albatros, L-59 Super Albatros, and the L-159 Alca.  It was founded in 1919.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-19T01:49:36.633" LastActivityDate="2015-05-19T01:49:36.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14838" PostTypeId="4" CreationDate="2015-05-19T00:25:11.503" Score="0" Body="Aero Vodochody is an aircraft manufacturer based in the Czech Republic." OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-19T01:49:20.913" LastActivityDate="2015-05-19T01:49:20.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14839" PostTypeId="5" CreationDate="2015-05-19T01:30:34.327" Score="0" Body="&lt;p&gt;The company currently exists as part of the United Aircraft Corporation holding company, and is headquartered in Moscow, Russia.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-19T02:06:21.167" LastActivityDate="2015-05-19T02:06:21.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14840" PostTypeId="4" CreationDate="2015-05-19T01:30:34.327" Score="0" Body="Yakovlev was a manufacturer of Soviet fighter aircraft during World War II.  It was founded in 1934." OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-19T02:06:16.583" LastActivityDate="2015-05-19T02:06:16.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14841" PostTypeId="1" AcceptedAnswerId="14847" CreationDate="2015-05-19T03:29:41.250" Score="16" ViewCount="3240" Body="&lt;p&gt;I was looking at pictures of Harrier jets and I noticed something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lvQpx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They have four landing gears. That seems pretty unusual for a fighter jet - most have only 3 in a triangle formation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this 4 point configuration? It seems to just add complexity and cost without really increasing stability. &lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="62" LastEditDate="2016-09-22T16:17:49.740" LastActivityDate="2018-10-26T12:06:02.300" Title="Why does the Harrier jet have four landing gears?" Tags="&lt;military&gt;&lt;landing-gear&gt;&lt;harrier&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14842" PostTypeId="1" CreationDate="2015-05-19T05:23:24.423" Score="3" ViewCount="286" Body="&lt;p&gt;As per my understanding, most of the Gyros in big jets are electric driven but I am not sure if the smaller planes also have the electric driven or vacuum/pressure driven Gyros?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="22726" LastEditDate="2019-01-04T04:16:48.877" LastActivityDate="2019-01-04T18:16:34.040" Title="What kind of Gyros are being used in smaller regional jets?" Tags="&lt;gyroscopic-instruments&gt;&lt;regional-jet&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14843" PostTypeId="2" ParentId="14829" CreationDate="2015-05-19T09:29:57.580" Score="24" Body="&lt;p&gt;This is a community-wiki mashup of the other answers - I thought a table would be useful.&lt;/p&gt;&#xA;&lt;div class=&quot;s-table-container&quot;&gt;&#xA;&lt;table class=&quot;s-table&quot;&gt;&#xA;&lt;thead&gt;&#xA;&lt;tr&gt;&#xA;&lt;th style=&quot;text-align: center;&quot;&gt;Date Introduced&lt;/th&gt;&#xA;&lt;th style=&quot;text-align: center;&quot;&gt;Aircraft Type&lt;/th&gt;&#xA;&lt;th style=&quot;text-align: left;&quot;&gt;Commercial Service (2015)&lt;/th&gt;&#xA;&lt;/tr&gt;&#xA;&lt;/thead&gt;&#xA;&lt;tbody&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1909&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;Bleriot XI&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Flown by Shuttleworth collection UK, entrance fee.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1932&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;JU-52&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Sight seeing flights by Ju-Air, Switzerland.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1932&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;Tiger Moth&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Flight experiences, e.g. Cheltenham UK.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1934&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;Dragon Rapide&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Sight seeing flights, London.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1935&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;DC-3&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Many commercial flight-experience/other operators.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1935&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;PBY Catalina&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Still used in aerial firefighting role.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1938&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;Piper Cub&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Many still in private/GA use and in flight schools.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1947&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;AN-2&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;Still in widespread use in 2020.&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1952&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;B-52&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;76 still in service with USAF. Projected service to 2045?&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;1952&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: center;&quot;&gt;Tu-95&lt;/td&gt;&#xA;&lt;td style=&quot;text-align: left;&quot;&gt;In service with Russian air force. Projected service to 2040?&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;/tbody&gt;&#xA;&lt;/table&gt;&#xA;&lt;/div&gt;" OwnerUserId="1289" LastEditorUserId="35166" LastEditDate="2020-12-16T14:09:27.880" LastActivityDate="2020-12-16T14:09:27.880" CommentCount="3" CommunityOwnedDate="2015-05-19T09:29:57.580" ContentLicense="CC BY-SA 4.0" />
  <row Id="14844" PostTypeId="5" CreationDate="2015-05-19T10:33:30.943" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-05-19T10:33:30.943" LastActivityDate="2015-05-19T10:33:30.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14845" PostTypeId="4" CreationDate="2015-05-19T10:33:30.943" Score="0" Body="The Aeronautical Information Manual (AIM) is published by the FAA, and contains flight information and ATC procedures when flying in US airspace." OwnerUserId="6919" LastEditorUserId="6919" LastEditDate="2015-05-19T11:21:56.393" LastActivityDate="2015-05-19T11:21:56.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14846" PostTypeId="1" AcceptedAnswerId="14857" CreationDate="2015-05-19T10:41:26.827" Score="2" ViewCount="1174" Body="&lt;p&gt;Are aircrafts insured? Basically, I want to ask who bears the financial liability in case of some mishap? The airline company/government or some other company.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-05-19T12:07:24.380" LastActivityDate="2015-05-19T14:33:15.430" Title="Are military and passenger jets insured?" Tags="&lt;insurance&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-06-19T08:20:02.180" ContentLicense="CC BY-SA 3.0" />
  <row Id="14847" PostTypeId="2" ParentId="14841" CreationDate="2015-05-19T10:58:48.903" Score="20" Body="&lt;p&gt;The main load bearing landing gear is in a bicycle setup, with 2 outriggers for stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows the gear to be lighter, stay close to the center and out of the way for the jet blast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_U-2&quot;&gt;Lockheed U-2&lt;/a&gt; also has its gear in the bicycle configuration and takes off and taxies with detachable &quot;pogo&quot; outriggers for stability.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="1696" LastEditDate="2015-05-19T14:40:22.863" LastActivityDate="2015-05-19T14:40:22.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14848" PostTypeId="2" ParentId="14818" CreationDate="2015-05-19T11:01:14.220" Score="4" Body="&lt;p&gt;The Register &lt;a href=&quot;http://www.theregister.co.uk/2015/05/19/airplane_hacking_panic_why_its_a_surely_a_storm_in_a_teacup/&quot; rel=&quot;nofollow noreferrer&quot;&gt;reported on this subject&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The links between the In-Flight-Entertainment (IFE) network and the Engine Indicating and Crew Alerting System (EICAS) is one-way. EICAS provides IFE with location and speed for display on maps.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;quot;IFE systems on commercial airplanes are isolated from flight and navigation systems,&amp;quot; Doug Alder, spokesman for Boeing Commercial, told El Reg. &amp;quot;While these systems receive position data and have communication links, the design isolates them from the other systems on airplanes performing critical and essential functions.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;At last year’s DEFCON hackers' meeting Dr Phil Polstra, professor of digital forensics at Bloomberg University (and a qualified commercial pilot and flight instructor), delivered a lecture on the feasibility of inflight aircraft hacking. It turns out it’s a lot more difficult than you might think.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;IFE systems do receive some information from the engine-indicating and crew-alerting system (EICAS), chiefly the aircraft’s location and speed for those little progress maps, but this data comes through a unidirectional Network Extension Device (NED).&lt;/p&gt;&#xA;&lt;p&gt;The EICAS gets its data from a hydromechanical controller which has an electronic interface, known as an EEC, and Roberts appears to be claiming that he overrode the EEC on one engine to produce the change of course.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;In order for this to actually happen he would need to be on a plane where the levels are not directly connected to the EEC, successfully compromise the EICAS, get the EEC to accept input from the EICAS (recall this is really a monitoring system), send a bogus mode change to climb, and somehow prevent the throttle quadrant from immediately sending a correct command,&amp;quot; he told the Reg.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;On top of this long list of conditions there are two basic facts that would make his actually flipping a plane on its side unlikely. First, jet engines do have a spool up time so this wouldn’t happen immediately. Second, the second a pilot touches the levers new signals will be sent to the EEC. When you put this all together it seems unlikely that Chris was able to ‘take over’ this plane as he claimed.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-19T11:01:14.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14849" PostTypeId="1" AcceptedAnswerId="14850" CreationDate="2015-05-19T11:33:59.677" Score="35" ViewCount="7511" Body="&lt;p&gt;I've noticed that when a WiFi system is set up on an aircraft, a small bulbous structure is added. What does it contain and how does this WiFi system work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/I7Yfd.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="4474" LastEditDate="2015-05-20T16:38:02.203" LastActivityDate="2015-05-20T16:38:02.203" Title="How does WiFi work on an aircraft?" Tags="&lt;aircraft-systems&gt;&lt;avionics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14850" PostTypeId="2" ParentId="14849" CreationDate="2015-05-19T12:15:58.890" Score="39" Body="&lt;p&gt;The small bulb houses the antenna that provides the satellite communications for the internet link. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the aircraft several wireless access points provide a WIFI signal to the passenger's equipment. The wireless access points are connected to a central modem which in turn is connected to the transceiver unit. The transceiver uses the rooftop antenna to communicate to a geostationary satellite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vjZrB.jpg&quot; alt=&quot;aircraft satellite antenna&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;source: &lt;a href=&quot;http://www.dailywireless.org/2010/10/08/jetblue-viasat-for-planefi/&quot;&gt;dailywireless&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dW4nm.jpg&quot; alt=&quot;MELCO antenna &quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;source: &lt;a href=&quot;http://www.flightglobal.com/blogs/runway-girl/2010/12/photo-under-the-lufthansa-blis/&quot;&gt;Flightglobal&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The antenna is a small dish or phased array that is aimed at the communication satellite using servo motors and/or electronic beam steering. The antenna control system receives information about the position and attitude of the aircraft to calculate the relative position to the geostationary satellites that provides the internet communications signal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also systems available on the market that use a ground based network to communicate with the internet. These systems cannot provide global coverage since the aircraft needs to be in line of radio sight of a ground based antenna.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-19T21:13:55.480" LastActivityDate="2015-05-19T21:13:55.480" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14851" PostTypeId="2" ParentId="14846" CreationDate="2015-05-19T12:22:24.847" Score="2" Body="&lt;p&gt;A partial answer for the case of military peacetime accidents: the government concerned seems to take responsibility for compensation - a few examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cavalese_cable_car_disaster_(1998)&quot; rel=&quot;nofollow&quot;&gt;Cavalese cable car disaster (1998)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/2012_Virginia_Beach_F/A-18_crash&quot; rel=&quot;nofollow&quot;&gt;2012 Virginia Beach F/A-18 crash&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="65" LastEditDate="2015-05-19T14:18:29.643" LastActivityDate="2015-05-19T14:18:29.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14852" PostTypeId="1" AcceptedAnswerId="14853" CreationDate="2015-05-19T12:37:33.997" Score="3" ViewCount="1696" Body="&lt;p&gt;For many years, the FAA prevented people from making phone calls during a flight. Was this because a phone call interfered with aircraft communications? &lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-19T14:35:06.660" Title="Why did FAA regulations initially prevent passengers from making phone calls during a flight?" Tags="&lt;radio-communications&gt;&lt;aircraft-systems&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2015-05-19T16:51:02.967" ContentLicense="CC BY-SA 3.0" />
  <row Id="14853" PostTypeId="2" ParentId="14852" CreationDate="2015-05-19T13:02:58.857" Score="5" Body="&lt;p&gt;While there is a chance it can interfere with aircraft equipment there are lots of other reasons as well. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It's disturbing, you would not want a can full of people yapping on their phones for 5 hours while others tried to sleep. Lets be honest does asking someone to &quot;Keep It Down&quot; ever really work. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's very taxing on the cell network itself. Without going into lots of detail about how &lt;a href=&quot;http://en.wikipedia.org/wiki/Cellular_network&quot; rel=&quot;nofollow&quot;&gt;cell phones work&lt;/a&gt;, the short and sweet of it is that when you are moving (say in a car) your phone is constantly hopping form tower to tower. At the speeds a plane moves at you would hop tower at a rate that would be far more taxing on the system than when you are in a car and could lead to dropped calls and other connection issues. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You need to listen up! While the laws on in flight entertainment have become more relaxed over time, one of the reasons you are not to use things during takeoff and landing is these are critical times in the flight (for something to go wrong) and if it does, you need to be attentive and able to listen to instructions. This, on some level, holds true for the whole flight as well I would think.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The phone itself occupies &lt;a href=&quot;http://en.wikipedia.org/wiki/Cellular_frequencies&quot; rel=&quot;nofollow&quot;&gt;its own frequency band&lt;/a&gt; outside of the band that &lt;a href=&quot;http://en.wikipedia.org/wiki/Airband&quot; rel=&quot;nofollow&quot;&gt;aircraft radios use&lt;/a&gt; however there is always a possibility when you have 2 EM waves that &lt;a href=&quot;http://en.wikipedia.org/wiki/Electromagnetic_interference&quot; rel=&quot;nofollow&quot;&gt;interference will occur&lt;/a&gt;.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-19T14:35:06.660" LastActivityDate="2015-05-19T14:35:06.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14854" PostTypeId="2" ParentId="14852" CreationDate="2015-05-19T13:04:42.650" Score="4" Body="&lt;p&gt;The use of personal electronic devices (including cell phones) during flight is still generally prohibited by the FAA, unless the operator or PIC allows it. FAR 91.21 the current wording on the use of electronic devices&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.21   Portable electronic devices.&#xA;  (a) Except as provided in paragraph (b) of this section, no person may operate, nor may any operator or pilot in command of an aircraft allow the operation of, any portable electronic device on any of the following U.S.-registered civil aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Aircraft operated by a holder of an air carrier operating&#xA;  certificate or an operating certificate; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Any other aircraft while it is operated under IFR.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Paragraph (a) of this section does not apply to—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Portable voice recorders;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Hearing aids;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Heart pacemakers;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Electric shavers; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Any other portable electronic device that the operator of the&#xA;  aircraft has determined will not cause interference with the&#xA;  navigation or communication system of the aircraft on which it is to&#xA;  be used.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) In the case of an aircraft operated by a holder of an air carrier&#xA;  operating certificate or an operating certificate, the determination&#xA;  required by paragraph (b)(5) of this section shall be made by that&#xA;  operator of the aircraft on which the particular device is to be used.&#xA;  In the case of other aircraft, the determination may be made by the&#xA;  pilot in command or other operator of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Advisory Circular 91-21-1C provides further details on how one may comply with this section and also advises that per FCC regulations part 22.925, the use of cell phones while &lt;strong&gt;airborne&lt;/strong&gt; is prohibited due to the potential for interference with ground-based communications networks (cell phone signals travel much farther from an airborne source vs. one the ground one) UNLESS the aircraft has special equipment installed in order to help reduce signal interference.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-05-19T13:04:42.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14855" PostTypeId="2" ParentId="14852" CreationDate="2015-05-19T13:07:03.687" Score="1" Body="&lt;p&gt;The prohibition on making phone calls is the domain of the Federal Communications Commission (FCC), not the FAA (the FAA has blanket bans on portable electronic devices but not the actual use to make phone calls).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FCC regulation question is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=47:2.0.1.1.2.8.27.12&quot; rel=&quot;nofollow&quot;&gt;47 CFR 22.925&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§22.925&lt;/strong&gt;   Prohibition on airborne operation of cellular telephones.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Cellular telephones installed in or carried aboard airplanes, balloons or any other type of aircraft must not be operated while such aircraft are airborne (not touching the ground). When any aircraft leaves the ground, all cellular telephones on board that aircraft must be turned off. The following notice must be posted on or near each cellular telephone installed in any aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“The use of cellular telephones while this aircraft is airborne is prohibited by FCC rules, and the violation of this rule could result in suspension of service and/or a fine. The use of cellular telephones while this aircraft is on the ground is subject to FAA regulations.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as I'm aware the original reasoning for this prohibition of airborne cellular phone usage dates back to the original analog cellular networks in the US.  The old analog system had issues when your phone could communicate with many towers at once and this was the case if you put the phone at some altitude above the ground giving clear line of sight to many towers.  This caused problems not only for the phone but also the network.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current digital cell networks do not have these kind of problems but for the most part are unusable at altitude due to design decisions of the network (primary radiation lobes are horizontal and sometimes down tilted relative to the horizon, not pointing up into the sky).  There are also issues with speed that make communicating with ground based towers possible (if you can talk to them at all).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An excerpt from the &lt;a href=&quot;https://www.fcc.gov/document/review-rules-wireless-services-onboard-aircraft-nprm&quot; rel=&quot;nofollow&quot;&gt;airborne cell NPRM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;6.&#xA;  Part 22 of the Commission’s rules prohibits the airborne use of 800 MHz cellular &#xA;  telephones, including the use of such phones on commercial and private aircraft. This prohibition was &#xA;  adopted in 1991 to guard against the threat of harmful interference from airborne use of cellular phones to &#xA;  terrestrial cellular networks. The Commission’s prohibition was not to ensure interference-free operation of avionics equipment. When the prohibition was adopted, the Commission noted that a cellular telephone used onboard an airborne aircraft would have greater range than a land-based handset, and its signal would be received by multiple terrestrial cell sites in a given market, causing harmful interference. Moreover, the Commission found that because a cellular telephone can transmit on all assigned 800 MHz cellular frequencies, a single handset could interfere with cellular systems in multiple cellular market areas simultaneously. Thus, the Commission concluded that “the need for noninterference in all cellular transmissions outweighs the benefits that would be realized by allowing the&#xA;  public to use cellular service in airborne aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FCC is going to make cell phone calls allowed at altitude, but only in conjunction with airborne cell sites that would be located on the plane.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="2401" LastEditDate="2015-05-19T13:39:09.723" LastActivityDate="2015-05-19T13:39:09.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14856" PostTypeId="2" ParentId="14841" CreationDate="2015-05-19T13:55:49.563" Score="17" Body="&lt;p&gt;The Harrier is designed around its rather large centerline engine with its 4 non-standard exhaust ports. In order to balance properly, the engine's nozzles have to be in just the right place and we can't have annoyances like landing gear doors opening just before landing and deflecting the thrust stream that is keeping the thing in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter jet wings are typically too thin to fold the gear into them like on some airliners (and the bombs / missiles get in the way too).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the gear gets to fold up into the space just behind the aft nozzles where it doesn't disturb anything important. In almost every other jet fighter the engine occupies this space instead. Yes, tricycle gear makes for easier landings but as this plane is designed to land straight down that isn't a big issue. And we tend not to put green pilots into the things either so if they do need a regular runway the driver should be fairly good.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="938" LastEditDate="2015-05-25T23:35:10.200" LastActivityDate="2015-05-25T23:35:10.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14857" PostTypeId="2" ParentId="14846" CreationDate="2015-05-19T14:33:15.430" Score="1" Body="&lt;p&gt;Commercial aircraft are insured in exactly the same way that companies insure other vehicles like cars. Broadly speaking, a company - the airline in this case - purchases hull insurance and liability insurance. The hull insurance covers damage to the aircraft and the liability insurance covers other costs like damage to property, medical payments, compensation to passengers and other costs caused by an event. &lt;a href=&quot;http://en.wikipedia.org/wiki/Lloyd%27s_of_London&quot; rel=&quot;nofollow&quot;&gt;Lloyd's of London&lt;/a&gt; has a &lt;a href=&quot;http://www.lloyds.com/Redirect-pages/Risk_locator/Aircraft_hull_and_liability_and_aviation_liability_insurance&quot; rel=&quot;nofollow&quot;&gt;useful summary&lt;/a&gt;. There are also all sorts of specialized insurance policies available to cover specific flights, aircraft, countries, cargoes etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small private aircraft can be insured in the same way, although many owners of older, less valuable aircraft don't buy hull insurance because over a period of years the premiums can be more than the value of the aircraft. Most pilots do carry liability insurance, however, to cover medical or other expenses for themselves and their passengers (although in the US at least there's no requirement for pilots to have any insurance at all).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know anything about military aircraft and it's a more complicated case: governments are &lt;a href=&quot;http://en.wikipedia.org/wiki/Sovereign_immunity&quot; rel=&quot;nofollow&quot;&gt;typically immune from liability&lt;/a&gt; (at least, you can't sue them) so it really depends on the legal situation and practices in each country.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-19T14:33:15.430" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14859" PostTypeId="1" CreationDate="2015-05-19T17:20:43.407" Score="3" ViewCount="476" Body="&lt;p&gt;Related to the question regarding &lt;a href=&quot;https://aviation.stackexchange.com/questions/14764/what-is-pressure-refuelling-and-how-does-it-work&quot;&gt;pressure refuelling&lt;/a&gt; and this one regarding &lt;a href=&quot;https://aviation.stackexchange.com/questions/14751/how-is-fuel-vapor-dealt-with-at-large-airports&quot;&gt;fuel vapors at large airports&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Refuelling an airplane involves putting fuel into tanks which are &quot;empty&quot; but are in fact full of dangerous air-fuel vapors. I do not believe many airplanes use &quot;bladder&quot; type flexible tanks which would avoid the creation of these airspaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When fuel goes in, the vapor has to go somewhere else. In contemporary cars, there is a vapor recovery both in the fuel system (activated carbon cylinder) as well as in the fuel nozzles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I understand both pressure refuelling as well as regular refuelling systems for airplanes and airliners, neither seem to have any sort of vapor recovery system. Wouldn't this be a considerable source of greenhouse gas emissions, let alone a tremendous fire hazard? Or is there a vapor recovery system being designed or implemented to mitigate this.&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-20T02:32:05.370" Title="Do airplanes have vapor recovery systems for refuelling?" Tags="&lt;aircraft-design&gt;&lt;aircraft-maintenance&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14861" PostTypeId="1" AcceptedAnswerId="14863" CreationDate="2015-05-19T18:35:31.073" Score="4" ViewCount="875" Body="&lt;p&gt;Is it the material used that allows the wing to flex or is wing flex caused by the structure of the wing?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-19T19:12:23.790" Title="What property of a wing allows it to flex?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14862" PostTypeId="2" ParentId="1183" CreationDate="2015-05-19T18:37:12.680" Score="3" Body="&lt;p&gt;The F-16 operates in a similar way to egid's answer.  There are 7 internal fuel tanks with the possibility of 3 external tanks.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the left system:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Left internal tank&#xA;A-1&#xA;Aft reservoir&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;On the right system:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Right internal tank&#xA;F-1&#xA;F-2&#xA;Fwd Reservoir&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Possible external tanks:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Left external tank (flows into left internal tank)&#xA;Right external tank (flows into right internal tank)&#xA;Centerline tank (flows between left and right system)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The external tanks flow into their respective internal tanks.  The reservoir tanks are the engine feed tanks that flow through the engine feedline to the fuel flow proportioner and eventually to the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting to your question...  The primary way fuel is transferred through the system is by siphoning using air ejectors.  However, this is only used in upright flight.  In addition there are boost pumps in the fuel tanks.  The #3 boost pump is actually near the top of one of the reservoir tanks and provides fuel during inverted flight.  While inverted, fuel does not transfer from the external tanks to their respective internal tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with this setup, the jet is restricted to only 30 seconds in MIL or less power and 10 seconds while in AB during negative G flight.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-05-19T18:37:12.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14863" PostTypeId="2" ParentId="14861" CreationDate="2015-05-19T18:56:30.417" Score="4" Body="&lt;p&gt;The amount a wing can flex is actually a product of the material. The wing requires a specified ultimate strength; with metal, that translates into a given amount of flex. This can be varied within limits, but it is really the material, its stiffness to yield point ratio, and its fatigue properties, that control how much a wing will flex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Carbon-fiber-reinforced_polymer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carbon-fiber-reinforced polymer&lt;/a&gt; is an extremely strong and light material and has lesser stiffness, and has essentially no fatigue problems. This is beneficial to provider a smoother ride in turbulence. The wing acts like a big spring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/14861/what-property-of-a-wing-allows-it-to-flex#comment34541_14861&quot;&gt;Federico mentioned&lt;/a&gt;, any material can and will flex (to a varying degree). So flexing is because of the material of the wing more than the wing itself.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-05-19T18:56:30.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14864" PostTypeId="1" AcceptedAnswerId="14867" CreationDate="2015-05-19T19:08:10.497" Score="18" ViewCount="8114" Body="&lt;p&gt;I've noticed that the nacelle outlet of the Lockheed Tristar is situated below the engine itself. It is at the end of the fuselage. The nacelle outlet of the tail engine of the DC-10 on the other hand, is at the same height as the engine. Why did Lockheed choose to lower the nacelle outlet? Perhaps this picture will help show you guys what I mean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/J0C1S.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="22726" LastEditDate="2018-12-30T23:27:10.623" LastActivityDate="2018-12-30T23:27:10.623" Title="Why is the nacelle outlet of the tail engine of the L-1011 Tristar lower than the engine itself?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;engine&gt;&lt;lockheed-tristar&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14865" PostTypeId="2" ParentId="14861" CreationDate="2015-05-19T19:12:23.790" Score="6" Body="&lt;p&gt;The flexing of a structure like an aircraft's wing is generally due to the materials used, but is also related to the nature of the structure itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In very simplified form, a wing is a beam that is supported at one end (the fuselage). Any forces such as from aerodynamics that act on the beam will cause it to bend. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All materials have a characteristic way in which they behave when load is applied. This can be expressed as stress (from applied forces) vs. strain (deformation of the material). Once the material reaches the yield strength point, it will be permanently deformed. For stress below this point, though, the material will return to its original shape. The wing can then flex as long as it remains below the yeild strength in all required loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kIOJo.png&quot; alt=&quot;Stress-strain graph&quot;&gt;&lt;br&gt;&#xA;&lt;sub&gt;&lt;a href=&quot;https://physics.stackexchange.com/q/16698/52596&quot;&gt;See here for more about this graph&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there is much more detail to the subject. The whole structure is designed together so that it will be as light as possible, but the amount of flexing is limited to prevent related issues. The wing may need to be made more stiff to prevent &lt;a href=&quot;https://aviation.stackexchange.com/q/5154/1696&quot;&gt;flutter&lt;/a&gt;. &lt;a href=&quot;https://aviation.stackexchange.com/a/14863/1696&quot;&gt;Farhan mentions fatigue&lt;/a&gt;, which can also limit the amount the wing may flex. The panels on top and bottom of the wing must also be prevented from breaking or permanently buckling. There are also fuel tank seals that should not be broken. Adding material in the right places can help to spread out the loads, which reduces the stress on the material and therefore reduces the amount of flexing.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-05-19T19:12:23.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14866" PostTypeId="1" CreationDate="2015-05-19T19:21:42.107" Score="3" ViewCount="2027" Body="&lt;p&gt;How I understand it, the perfect propeller would move air rearward at the exact same velocity as the free stream, i.e. the propeller air will merge with the free stream and have no real influence on the flow-field over the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However a non-ideal propeller (thus all real propellers) accelerates the air to a higher speed than the free-stream and thus alters the flow-field over the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: Does this airflow from the propeller increase the lift generated by the wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question obviously assumes that the propeller and wing is in the same plane and that the air from the propeller thus hits the wing.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2015-05-19T22:34:17.317" Title="Does the airflow from a propeller over a wing contribute to lift?" Tags="&lt;propeller&gt;&lt;lift&gt;&lt;fluid-mechanics&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2015-05-19T23:06:29.870" ContentLicense="CC BY-SA 3.0" />
  <row Id="14867" PostTypeId="2" ParentId="14864" CreationDate="2015-05-19T19:21:58.087" Score="22" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14864/why-is-the-nacelle-outlet-of-the-tail-engine-of-the-l-1011-tristar-lower-than-th#comment34543_14864&quot;&gt;As Federico points out&lt;/a&gt;, the engine is located directly in front of the exhaust portion. This is true for almost all engines with ducted arrangements. It's much easier to duct the cool, slow intake air to the engine than duct the hot, fast exhaust air away from it, for both temperature and drag reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this cutaway you can see the intake duct leading down to where the engine is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LPDHp.jpg&quot; alt=&quot;L-1011 Cutaway View&quot;&gt;&#xA;&lt;br&gt;&lt;sub&gt;&lt;a href=&quot;http://aircraft.wikia.com/wiki/Lockheed_L-1011_Tristar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting the exhaust nozzle lower allows more room for rudder above it. Putting the nozzle higher, like on the DC-10 series, means the rudder is pushed higher up the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This arrangement keeps the rudder as close to the vertical center of gravity as possible, which reduces the stress on the tail and limits the rolling motion induced by the rudder. It also keeps the engine forces close to the vertical center of gravity. This configuration also allows the supports to tie in to the existing structure at the rear of the fuselage. Placing the engine further up the tail would add surface area (and therefore drag), and require additional structure to support the engine above the fuselage.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-05-19T19:21:58.087" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14868" PostTypeId="2" ParentId="14864" CreationDate="2015-05-19T19:23:31.280" Score="11" Body="&lt;p&gt;This arrangement of placing the engine intake duct above the fuselage is called &lt;a href=&quot;http://en.wikipedia.org/wiki/S-duct&quot; rel=&quot;nofollow noreferrer&quot;&gt;S-duct&lt;/a&gt; (Thanks &lt;a href=&quot;https://aviation.stackexchange.com/questions/14864/why-is-the-nacelle-outlet-of-the-tail-engine-of-the-l-1011-tristar-lower-than-th#comment34544_14864&quot;&gt;Terry&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer of &lt;strong&gt;why&lt;/strong&gt; would be it is how it was designed, probably as a differentiating feature. This is &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot; rel=&quot;nofollow noreferrer&quot;&gt;vaguely mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... a small vertical fin [is] between the bottom of the middle engine&#xA;  intake and the top of the fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the pictures below (&lt;a href=&quot;http://aircraft.wikia.com/wiki/Lockheed_L-1011_Tristar&quot; rel=&quot;nofollow noreferrer&quot;&gt;images' source&lt;/a&gt;), it appears that what &lt;a href=&quot;https://aviation.stackexchange.com/questions/14864/why-is-the-nacelle-outlet-of-the-tail-engine-of-the-l-1011-tristar-lower-than-th#comment34543_14864&quot;&gt;Federico stated&lt;/a&gt; appears to be true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2u9CH.jpg&quot; alt=&quot;Picture 1&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ME8tM.jpg&quot; alt=&quot;Picture 2&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-05-19T19:49:25.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14869" PostTypeId="2" ParentId="14866" CreationDate="2015-05-19T20:32:07.897" Score="5" Body="&lt;p&gt;A propeller not affecting the velocity of the free stream air would not generate any thrust (or drag), as the propeller works by the principle of creating thrust by accelerating a large mass of air, $F = m * a$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accelerated airflow from the propeller does generally increase the lift generated by the wing. The amount of lift increase depends on the configuration (how exposed the wing is to the slipstream of the propeller). This tends to be particularily noticeable on light twins:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3xn8M.jpg&quot; alt=&quot;Piper Seminole&quot;&gt;&#xA;(Image attribution: Wikimedia Commons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also another effect on lift, coming from the corkscrew-shaped vortex of the propeller slipstream, perhaps more noticeable on single engine aircraft:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/KDk2d.png&quot; alt=&quot;Slipstream&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Image attribution: FAA Pilots Handbook of Aeronautical Knowledge)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image is a little bit unfortunate, as it demonstrates another effect as well (yaw from the slipstream), but you can also see how propeller slipstream will affect the flow pattern around the wing roots: on one side, it will tend to increase the effective angle of attack, leading to higher lift on that side, and on the other side it will decrease the effective angle of attack, decreasing lift on that side, leading to a roll-moment. This effect of course exists in twin engine aircraft too, but may be less noticeable, as the effect is more symmetrical, in the case of co-rotating propellers, or even symmetrical (in the case of counter-rotating propellers).&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-19T22:34:17.317" LastActivityDate="2015-05-19T22:34:17.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14870" PostTypeId="2" ParentId="14597" CreationDate="2015-05-19T20:56:16.773" Score="9" Body="&lt;p&gt;&lt;strong&gt;Estimations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can at least estimate a reverse thrust case based on some numbers and some physics, a bit of a specific case of &lt;a href=&quot;https://aviation.stackexchange.com/q/14521/1696&quot;&gt;this question&lt;/a&gt;. The stopping distance equation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$d_f=\frac{v_i^2}{2a}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information &lt;a href=&quot;http://www.tsb.gc.ca/eng/rapports-reports/aviation/2010/a10a0032/a10a0032.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;in Appendix B here&lt;/a&gt; for the 727-200 gives stopping distances for different cases. If we look at a sea level pressure altitude case with 120,000 lb gross weight, the stopping distance is 2452 feet. The correction for a reversers only case is 2.57, bringing the distance to 6302.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a landing speed of &lt;a href=&quot;http://www.boeing-727.com/Data/fly%20odds/thumb.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;200 ft/s&lt;/a&gt;, the plane will take 11500 lb of force to stop in that distance. Each engine on the 727-200 provides 14500 lb of thrust force maximum. Considering that part of the stopping force will be provided by drag and surface friction, the reverse thrust is about 25% of the maximum forward thrust. The reversers will be more effective at higher air speeds, so the maximum will be higher than this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure 39.5 &lt;a href=&quot;https://books.google.com/books?id=V1DuJfPov48C&amp;amp;lpg=PA511&amp;amp;pg=PA511#v=onepage&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; shows a graph of reverse thrust compared to forward thrust for different bypass ratios and reverse thrust types. This is a good check for a general case. The GEnx-1B64 has a bypass ratio of about 10, and reverses the fan but not the primary exhaust, which gives a ratio of 30% of maximum forward thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine will not run at full power when in reverse mode, so accounting for this and the bypass ratio will leave you with about states that modern thrust reversers can convert up to &lt;a href=&quot;http://dx.doi.org/10.1007/978-3-642-34539-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;35% to 50%&lt;/a&gt; of their forward thrust into reverse thrust.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-12-07T22:30:50.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14871" PostTypeId="1" AcceptedAnswerId="14880" CreationDate="2015-05-20T02:05:24.220" Score="7" ViewCount="680" Body="&lt;p&gt;Boeing's Dreamliners have been hit several times by small bugs, like fires in the batteries or other engineering issues. Are such incidents frequent when new types are introduced, and how much has the situation improved one year later?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="1696" LastEditDate="2015-05-20T15:09:10.333" LastActivityDate="2015-05-20T15:09:10.333" Title="How much is the Boeing 787 Dreamliner affected by teething troubles now, one year after commencing commercial operations?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;faa&gt;&lt;boeing-787&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14873" PostTypeId="1" AcceptedAnswerId="14878" CreationDate="2015-05-20T02:23:13.773" Score="6" ViewCount="138" Body="&lt;p&gt;Specific case:  I have a student who is ready for his ride, but he has not yet scheduled it, and because I'm moving, I will be permanently unavailable to endorse it in a few days.  I want to add a stipulation to his endorsement that says the endorsement is valid only until a certain date, and it's only valid if he has had some number of hours of flight training within the preceding $x$ days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither of these items are mentioned in AC 61-65.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;General case:  &lt;strong&gt;How much can I legally deviate from the guidance for checkride endorsements given in AC 61-65?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="167" LastEditDate="2015-05-20T02:56:04.800" LastActivityDate="2015-05-20T04:50:10.470" Title="To what extent can I deviate from the endorsement guidance given in AC 61-65?" Tags="&lt;faa-regulations&gt;&lt;logbook-endorsements&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14874" PostTypeId="2" ParentId="14859" CreationDate="2015-05-20T02:32:05.370" Score="3" Body="&lt;p&gt;You are correct on both your assumptions about the fuel vapour. It does have a greenhouse effect, though I would suspect that the amount of fuel required to make the air saturated in the fuel tank is not likely to be more than some tens of grams. It also presents a fire hazard.&lt;br&gt;&#xA;However we again face the same issue as with many other systems that would be environment-friendly and safe: the cost.&lt;br&gt;&#xA;Companies, both airlines and airport operators, carefully evaluate all cost to benefits. In this particular case the environmental effect is likely to be considered neglible, and the fire risk is tackled with other measures, such as grounding, clear-areas, ventilation etc. Those were covered nicely in the previous questions.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-05-20T02:32:05.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14875" PostTypeId="1" CreationDate="2015-05-20T03:12:53.553" Score="67" ViewCount="74914" Body="&lt;p&gt;Besides the fact that it's now a standard, why do American-English-speaking pilots and ATC say &quot;Niner&quot; instead of &quot;Nine&quot;?  None of the other numerals are pronounced in an atypical fashion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what was &quot;Nine&quot; being mistaken that resulted in the &quot;Niner&quot; standard being adopted?&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="2176" LastEditDate="2015-05-20T13:40:25.227" LastActivityDate="2019-01-17T18:07:04.033" Title="Why do English-speaking pilots and ATC say &quot;Niner&quot; instead of &quot;Nine&quot;?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="14876" PostTypeId="2" ParentId="14875" CreationDate="2015-05-20T04:03:48.447" Score="91" Body="&lt;p&gt;According to &lt;a href=&quot;http://en.wikipedia.org/wiki/NATO_phonetic_alphabet#Pronunciation&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pronunciation of the digits 3, 4, 5, and 9 differs from standard English – being pronounced &lt;em&gt;tree, fower, fife,&lt;/em&gt; and &lt;em&gt;niner&lt;/em&gt;. The digit 3 is specified as &lt;em&gt;tree&lt;/em&gt; so that it is not pronounced &lt;em&gt;sri&lt;/em&gt;; the long pronunciation of 4 (still found in some English dialects) keeps it somewhat distinct from &lt;em&gt;for&lt;/em&gt;; 5 is pronounced with a second &quot;f&quot; because the normal pronunciation with a &quot;v&quot; is easily confused with &quot;fire&quot; (a command to shoot); &lt;strong&gt;and 9 has an extra syllable to keep it distinct from German &lt;em&gt;nein&lt;/em&gt; 'no'&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The phonetic alphabet is not a random selection of words. It was created very carefully taking dialects into account, so as not to confuse any of the letter with possible mispronunciations. Although they are &quot;English&quot; words, the choices were made with the world in mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned on the &lt;a href=&quot;http://en.wikipedia.org/wiki/NATO_phonetic_alphabet#Code_words&quot;&gt;same article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The final choice of code words for the letters of the alphabet and for the digits was made after hundreds of thousands of comprehension tests involving 31 nationalities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-05-20T13:40:56.930" LastActivityDate="2015-05-20T13:40:56.930" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="14877" PostTypeId="1" AcceptedAnswerId="14879" CreationDate="2015-05-20T04:22:25.687" Score="4" ViewCount="5418" Body="&lt;p&gt;I logged into my flying club's online scheduling website today (May 19, 2015) and it was warning me that my &lt;a href=&quot;http://en.wikipedia.org/wiki/Biennial_flight_review&quot; rel=&quot;nofollow&quot;&gt;Flight Review&lt;/a&gt; was about to expire (on May 31, 2015). My last flight review was on June 7, 2013.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.56&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.56 (c)&lt;/a&gt;, the look-back period runs from &lt;em&gt;(my emphasis added)&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the beginning of the 24th calendar month &lt;strong&gt;before&lt;/strong&gt; the month in&#xA;  which that pilot acts as pilot in command ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So am I right in calculating that my last Flight Review is actually valid through June 30, 2015?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="65" LastEditDate="2015-05-20T13:53:41.850" LastActivityDate="2018-10-26T12:28:33.977" Title="When is my biennial flight review due?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14878" PostTypeId="2" ParentId="14873" CreationDate="2015-05-20T04:50:10.470" Score="3" Body="&lt;p&gt;Advisory Circulars by definition, are advisory and not regulatory in nature (Chapter 1, paragraph 3 of &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/1320.46C.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Order 1320.46C&lt;/a&gt;). Therefore, &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-65E_CHG_1.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 61-65&lt;/a&gt; provides &lt;em&gt;suggested&lt;/em&gt; language that will ensure compliance with the FARs.  You are free to word the endorsements differently, but if the examiner takes issue with your endorsement, the student may not have any recourse but to have the entries redone (by you, or another CFI).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you say your student is ready (I am assuming for their Private Pilot check ride), why not go ahead and endorse them right now? &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.109&quot; rel=&quot;nofollow&quot;&gt;FAR 61.109(a)(4)&lt;/a&gt; requires the student to receive 3 hours of flight training within the two months prior to the test, this would cause your endorsement to automatically expire if they don't test (or receive additional training) within that window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, I would suggest contacting the local &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot; rel=&quot;nofollow&quot;&gt;Flight Standards District Office&lt;/a&gt; and get guidance from them directly.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-05-20T04:50:10.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14879" PostTypeId="2" ParentId="14877" CreationDate="2015-05-20T05:33:57.873" Score="5" Body="&lt;p&gt;Yes. Your interpretation is the correct one. Several FAA legal interpretations cover the &quot;calendar months&quot; phrasing; the best I could find was &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2012/harvey-morrisonmahoney%20-%20(2012)%20legal%20interpretation.pdf&quot; rel=&quot;noreferrer&quot;&gt;the Harvey interpretation from 2012&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Based on the facts that you have presented, a biennial flight review accomplished on April 2, 2002, would not lapse until May 1, 2004.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, your flight review is legal until the end of the month (ie, June, or August) it was completed in two years before. The same calendar logic applies to maintenance like the annual inspection. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-05-20T05:40:27.460" LastActivityDate="2015-05-20T05:40:27.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14880" PostTypeId="2" ParentId="14871" CreationDate="2015-05-20T06:08:06.697" Score="7" Body="&lt;p&gt;You can get a rough idea by &lt;a href=&quot;http://avherald.com/h?search_term=B788&amp;amp;dosearch=1&quot;&gt;searching B788¹ on AvHerald&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines &lt;em&gt;do&lt;/em&gt; report technical problems² to their overseeing aviation safety board (in India it is, somewhat unusually, part of the civil aviation authority, DGCA; in most countries it is a separate agency, e.g. NTSB in USA). And those publish them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also for technical problems, aviation safety board of country of manufacture would be consulted, so NTSB should know about most technical problems of B787 and it should be possible to find them in their bulletins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://avherald.com/h&quot;&gt;Aviation Herald&lt;/a&gt; collects such reports from various sources. Only incidents that occur in flight get reported and only “interesting” subset of them, but if there were any serious problems with a type, they would come up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further if some problem requires mitigation steps to be taken, the civil aviation authorities publish airworthiness directives, that describe steps airlines must take (and under which conditions and until when) to be permitted to operate the aircraft. Since Boeing is based in USA, any airworthiness directive regarding it would most likely be first published by FAA and usually taken over by aviation authorities in other countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, the batteries were the only serious issue of B787 that required immediate modification throughout the fleet. There are many small ones, like any aircraft, but there does not seem to be anything else that would be significantly more common or serious than on other types.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ AvHerald lists aircraft by their ICAO identifiers in the article titles (and full name in the text). The ICAO identifiers distinguish the series, so Boeing 787-8 gets B788.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² Those that affect safety. So non-working in-flight entertainment would not have to be reported, but a short-circuit in it should be.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-05-20T06:16:11.863" LastActivityDate="2015-05-20T06:16:11.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14881" PostTypeId="1" AcceptedAnswerId="14882" CreationDate="2015-05-20T07:15:36.037" Score="6" ViewCount="23578" Body="&lt;p&gt;All I am aware of is that flutter testing involves the aircraft shaking violently. How is a flutter test performed and what is its purpose?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-20T08:13:40.267" Title="What is the purpose of flutter testing?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;aircraft-certification&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14882" PostTypeId="2" ParentId="14881" CreationDate="2015-05-20T08:02:26.850" Score="12" Body="&lt;p&gt;Flutter is a phenomenon that can occur when a structure is subjected to aerodynamic forces. It occurs not only in aircraft but also for example in buildings, power lines, road signs and bridges. Flutter is an oscillation caused by interaction of aerodynamic forces, structural elasticity and inertial effects. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the best known example of flutter is the bridge over the &lt;a href=&quot;https://www.youtube.com/watch?v=j-zczJXSxnw&quot; rel=&quot;noreferrer&quot;&gt;Tacoma Narrows ('Gallopin' Gertie')&lt;/a&gt;  that collapsed due to flutter in gale force winds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lRnsi.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flutter in aircraft causes the wings and / or stabilizers to oscillate. &#xA;When the airspeed increases the energy added in each oscillation to the structure by the aerodynamic forces increases. At some speed the damping of the structure may be insufficient to absorb the energy increase from the aerodynamic loads and the amplitude of the harmonic oscillations will grow until the structure breaks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flutter test is performed to determine what speed flutter occurs yet is still damped. Theoretically an aircraft should be able to stay structurally intact up to the design dive speed ($V_d$) which is at least 1.4 times the design cruise speed. In flight tests, the $V_d$ is not always demonstrated as this is very risky since there would not be any margin from breaking up. The maximum speed is slowly increased in subsequent flight tests with careful data analyses in between up to a point where the test team decides that it is no longer safe to continue. This establishes the maximum demonstrated dive speed ($V_{df}$); the published maximum operating speed ($V_{mo}$) and never-exceed speed ($V_{ne}$) are well below $V_{df}$ to give margin from disaster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=6mbIRXnCSts&quot; rel=&quot;noreferrer&quot;&gt;video shows flutter&lt;/a&gt; in a Hawker 800. The incident occurred not during testing but was caused by &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/dc7bd4f27e5f107486257221005f069d/9a2257a29346c71686257c300065c252/$FILE/NM-14-05.pdf&quot; rel=&quot;noreferrer&quot;&gt;inadequate fitting of the ailerons&lt;/a&gt;&lt;sup&gt;(FAA PDF)&lt;/sup&gt;. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-20T08:13:40.267" LastActivityDate="2015-05-20T08:13:40.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14883" PostTypeId="1" AcceptedAnswerId="14885" CreationDate="2015-05-20T08:04:39.300" Score="4" ViewCount="1877" Body="&lt;p&gt;Would the pilot ever pitch down (even slightly) during a flight, or would he/she simply reduce power to reduce altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is not similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb&quot;&gt;Why do airplanes lift up their nose to climb? (asked by Chris)&lt;/a&gt; for it the reasons aircraft pitch up. This question is looking for an answer that explains if and when a pilot pitches down during a flight to reduce altitude, the very opposite of the question of @Chris.&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-08-03T22:18:43.277" Title="Is there any part of a flight where the pilot would pitch down?" Tags="&lt;aircraft-performance&gt;&lt;pilots&gt;&lt;pilot-technique&gt;" AnswerCount="5" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14884" PostTypeId="2" ParentId="14881" CreationDate="2015-05-20T08:10:17.570" Score="3" Body="&lt;p&gt;Aeroelastic flutter is a dynamic instability of an elastic structure where there is feeding between the deformation of the structure and the force provided by the aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is a very dangerous condition where the vibration on the structure keeps growing and so the stress over it, endangering safe flight. It is a condition that needs to be completely avoided in a commercial flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane manufacturers need to provide information to airlines of the operation envelope of the airplane, and part of that information is to include region of flutter to be avoided (or maximum time on it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For providing such information manufacturers predict using internal methods (usually simulation) the flutter speed for each condition, but certification authorities request that a physical test is perform to detect the flutter velocity which will be the final speed provided in the airplane manuals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is made? Taking an specific airplane weight the flight test pilots approach steadily step by step to the flutter speed until certain level of vibration is obtained, determining the final airplane flutter speed.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-05-20T08:10:17.570" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14885" PostTypeId="2" ParentId="14883" CreationDate="2015-05-20T08:31:43.603" Score="14" Body="&lt;p&gt;The most common case to pitch down is to speed up, not to reduce altitude, for example when transitioning from a climb (at climb speed) to level flight (accelerating to cruise speed). You can transition to level flight by reducing thrust, but that'll leave you level at climb speed, and is usually not what you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing configuration will usually require pitching changes to maintain stable flight. In particular during the approach-to-landing, extending the flaps will substantially increase the drag, and in order to maintain airspeed, you'll need to pitch the nose down. If you don't, you'll bleed off airspeed and potentially eventually stall unless you overpower the drag with thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are of course unusual circumstances that will require a pitch-down as well, obstacle avoidance for example (e.g. airplanes). As mentioned in the comments, to make a speedy descent you'll probably also want to pitch down (such as in case of pressurization problems or fire on board).&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-05-24T09:54:20.293" LastActivityDate="2015-05-24T09:54:20.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14886" PostTypeId="2" ParentId="14883" CreationDate="2015-05-20T08:36:41.513" Score="4" Body="&lt;p&gt;I'm going to interpret &quot;normal&quot; as cruise level of a commercial flight. Normal for other types of flying might have different answers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In level flight pitch is regularly adjusted both up and down to maintain the  chosen altitude. Generally these adjustments are small enough that they are not noticed by passengers or crew, especially with an autopilot engaged. So is it very normal to pitch down in small increments without changing power settings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With larger changes in pitch, for example when descending from cruise level, typically thrust is reduced or increased to maintain airspeed. It would be unusual to pitch down before reducing power, or pitch up before increasing it. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-05-20T08:36:41.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14887" PostTypeId="2" ParentId="14829" CreationDate="2015-05-20T09:08:21.730" Score="3" Body="&lt;p&gt;The USAF B-52 first flew in 1952, stopped production in 1962, is still a frontline bomber, and is projected to continue service until 2045&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot; rel=&quot;nofollow&quot;&gt;http://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8552" LastActivityDate="2015-05-20T09:08:21.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14888" PostTypeId="1" AcceptedAnswerId="15225" CreationDate="2015-05-20T10:56:26.823" Score="10" ViewCount="6015" Body="&lt;p&gt;Why do most Boeing aircraft and their corresponding Airbus counterparts have different flaps and slats mechanisms (747 and A380, 737 and A320)? I'm assuming a lot of these mechanisms are patented. For example, the 747 is equipped with &lt;a href=&quot;http://www.skybrary.aero/index.php/Krueger_Flaps&quot; rel=&quot;noreferrer&quot;&gt;Krueger&lt;/a&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Krueger_flap&quot; rel=&quot;noreferrer&quot;&gt;flaps&lt;/a&gt; while the A380 has the leading edge &lt;a href=&quot;http://en.wikipedia.org/wiki/Droop_%28aeronautics%29&quot; rel=&quot;noreferrer&quot;&gt;droop&lt;/a&gt; as &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading-edge_slats&quot; rel=&quot;noreferrer&quot;&gt;slats&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mx1Aw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="8346" LastEditDate="2015-05-30T13:58:18.970" LastActivityDate="2018-03-15T20:02:29.707" Title="Why do similar Airbus and Boeing aircraft use different flap and slat mechanisms?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;aircraft-systems&gt;&lt;flaps&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14889" PostTypeId="1" CreationDate="2015-05-20T11:39:21.803" Score="2" ViewCount="4510" Body="&lt;p&gt;Why are passengers requested to close their window blinds during a night-time takeoff?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand why they are asked to open them during day-time take-offs and landings - probably because rescue teams can look inside in the case of a crash. But what´s the point in closing them at night?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason I can think of is that people might mistake the cabin lights for landing lights, hence misjudging the planes orientation. Still, it is very difficult to mistake a row of cabin lights for landing lights?&lt;/p&gt;&#xA;" OwnerUserId="47549" LastEditorUserId="1696" LastEditDate="2015-10-07T14:38:50.700" LastActivityDate="2015-10-07T14:38:50.700" Title="Why are passengers requested to close their window blinds during a night-time takeoff?" Tags="&lt;takeoff&gt;&lt;windows&gt;" AnswerCount="1" CommentCount="11" ClosedDate="2015-10-07T15:22:53.250" ContentLicense="CC BY-SA 3.0" />
  <row Id="14890" PostTypeId="1" AcceptedAnswerId="14892" CreationDate="2015-05-20T12:15:36.193" Score="8" ViewCount="798" Body="&lt;p&gt;Are aircraft &lt;em&gt;flown&lt;/em&gt; differently because boxes don't complain about more abrupt changes in direction, speed, altitude, etc where passengers might. i.e. if the cargo is incapable of loading itself, is it subjected to a more aggressive flight regimen than if the cargo is self-loading and potentially complaint-filing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that Boeing, Airbus and other manufacturers produce essentially identical airframes in both passenger and cargo configurations, so they would have essentially identical flight envelopes, I just wonder if cargo flights are taken closer to the extremes.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-05-20T13:09:31.703" Title="Are cargo and passenger flights flown differently?" Tags="&lt;passenger&gt;&lt;flight-planning&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14891" PostTypeId="1" AcceptedAnswerId="14947" CreationDate="2015-05-20T12:22:00.727" Score="5" ViewCount="897" Body="&lt;p&gt;For as long as I can remember, seats 1A/1B suffer from rain during acceleration/takeoff as the condensation pours down from the heavens, (well, the overhead panel where the reading lights, gaspers, etc. are).  I guess it was, at most, a minor inconvenience until pax started carrying more consumer electronics in their hands. Now it can be costly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, I can fix the issue myself by avoiding those seats, but sometimes they're the only extra-legroom seats left, and I'm tall. I try to remember to keep my electronics pocketed until after takeoff, but it's so boring sitting there while 188 other pax try to stuff their inflated bags into straining lockers, and I forget.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can understand that this rotation rain, or similar aggravation, might happen on a new aircraft design; something undetected until mass operations and not safety-critical anyway, but how is this still happening on an aircraft that first flew decades ago and has had so many enhancements?  I can't be the only one who has had a Seattle soaking, so why has this, possibly costly, annoyance not been fixed?  It can't be that difficult/expensive to cure, surely?&lt;/p&gt;&#xA;" OwnerUserId="3264" LastEditorUserId="1696" LastEditDate="2015-05-20T14:57:08.370" LastActivityDate="2015-05-21T15:41:21.113" Title="Why, after decades of redesign and enhancement, does it still rain inside B737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14892" PostTypeId="2" ParentId="14890" CreationDate="2015-05-20T13:09:31.703" Score="9" Body="&lt;p&gt;Yes, cargo and passenger aircraft of the same basic model are sometimes flown differently when there is no live cargo. A friend of mine who flies cargo put it almost exactly as you did in your question when you say boxes cannot complain, so he sometimes hand flies the aircraft when passenger pilots would be required to use autopilot. Cargo pilots don't have to worry about tender stomachs in the back, so steeper climbs and descents and tighter turns are acceptable as long as the aircraft remains well within the flight envelope. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-05-20T13:09:31.703" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14893" PostTypeId="1" AcceptedAnswerId="14900" CreationDate="2015-05-20T13:34:38.593" Score="5" ViewCount="1215" Body="&lt;p&gt;Say I'm flying heading 275 and am headed in to land on runway 16 at a towered airport in Class D airspace. I'm 8 miles to the east and have been cleared: &quot;report 2 mile left base runway 16&quot;. Should I go for a standard 45 degree traffic pattern entry to downwind at midfield or should I fly straight to the base and report when 2 miles east of the runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case I went straight for the base and reported and didn't get yelled at by the controller but I'm curious what the correct thing to do is in this situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not asking what a 2 mile base is, I'm asking where I should enter the pattern if instructed to report on 2 mile base.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="572" LastEditDate="2015-05-20T16:19:41.437" LastActivityDate="2015-05-20T16:19:41.437" Title="Where should I enter the pattern when instructed to report a 2-mile left base?" Tags="&lt;faa-regulations&gt;&lt;approach&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14894" PostTypeId="1" AcceptedAnswerId="14897" CreationDate="2015-05-20T13:49:12.597" Score="20" ViewCount="6687" Body="&lt;p&gt;I understand that an &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_boneyard&quot;&gt;aircraft boneyard&lt;/a&gt; is an amazing tourist attraction for aviation enthusiasts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the number of planes that the &lt;a href=&quot;http://en.wikipedia.org/wiki/Davis%E2%80%93Monthan_Air_Force_Base&quot;&gt;boneyard in Tucson&lt;/a&gt; has accumulated today is mind-boggling. I know that, initially, the purpose of the boneyard was to salvage materials from old and obsolete aircraft. However, the pace at which most aircraft are being scrapped is very low. Though it serves as a spectacular sight, why is the boneyard still active?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="6919" LastEditDate="2015-05-21T06:15:14.970" LastActivityDate="2015-05-27T10:30:10.117" Title="Why is the aircraft boneyard in Tucson, Arizona still active?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-disposal&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14896" PostTypeId="2" ParentId="14877" CreationDate="2015-05-20T14:02:27.767" Score="2" Body="&lt;p&gt;As far as the FAA is concerned, your Flight Review is valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may be running into a case where flight clubs can and often do create their own, more stringent rules.&#xA;They can require a BFR &lt;em&gt;within&lt;/em&gt; two years, so you don't get the extra fractional-month grace period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They could even require some currency-demonstration every few months!&lt;br&gt;&#xA;Their planes, their rules.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-05-20T14:02:27.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14897" PostTypeId="2" ParentId="14894" CreationDate="2015-05-20T14:07:33.190" Score="19" Body="&lt;p&gt;If the number of planes waiting on getting gutted isn't decreasing even though scrapping activities are happening that means there is a steady influx of end-of-life planes arriving to get scrapped. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as there are planes and new planes being built (most have a lifespan of a few decades) there will be planes that need to get scrapped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can't just dump the plane on a landfill or you will get nature activists on your case about the hazardous materials (hydraulic fluid, remnant fuel, ...) and recycle potential. Plus most components (instruments, engines, the espresso machine in the galley, etc) will still be usable and airliners will want to buy them as spares.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-05-27T10:30:10.117" LastActivityDate="2015-05-27T10:30:10.117" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14898" PostTypeId="1" AcceptedAnswerId="14902" CreationDate="2015-05-20T14:20:20.457" Score="4" ViewCount="2307" Body="&lt;p&gt;Aircraft could fly low for various reasons,  Common reasons for low flight are sightseeing, photography, crop dusting, staying below Bravo/Charlie airspaces, flybys, and &quot;just cause I felt like it&quot;.  What are the  difficulties and dangers faced by such aircraft? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-24T17:47:39.280" LastActivityDate="2015-06-25T20:05:42.530" Title="What are the difficulties and dangers faced by low flying aircraft?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14899" PostTypeId="1" AcceptedAnswerId="14915" CreationDate="2015-05-20T14:32:44.970" Score="4" ViewCount="1865" Body="&lt;ol&gt;&#xA;&lt;li&gt;What is static electricity discharging noise ? &lt;/li&gt;&#xA;&lt;li&gt;How does this phenomena affect radio communications ? &lt;/li&gt;&#xA;&lt;li&gt;Does the discharging happen through lightning and are static discharger  fixed or are they removable - such as telescopic i mean ? &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="19" LastEditDate="2016-07-14T07:49:15.453" LastActivityDate="2016-07-14T07:49:15.453" Title="What is static discharging noise and what is its effect on radio communications?" Tags="&lt;aircraft-design&gt;&lt;radio-communications&gt;&lt;lightning&gt;&lt;static-electricity&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14900" PostTypeId="2" ParentId="14893" CreationDate="2015-05-20T14:36:50.737" Score="4" Body="&lt;p&gt;I'm assuming you're more interested in the base-or-downwind question rather than the where-is-the-2-mile-base question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically you're supposed to fly the published procedure unless told otherwise. In this case the procedure would probably be a standard traffic pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being told to 'report' means only that, you should report it when you're there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not to be confused with the (in my experience) more common instruction &quot;Enter and report a 2 mile base for runway 16&quot;, in which case you head for the base and not the downwind, and you report it when you get there. To argue ad absurdum, the clearance &quot;Cleared touch and go, after the touch and go, make left traffic, report mid-field downwind&quot; doesn't mean you should head straight for the downwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As always, when in doubt, ask.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-05-20T14:42:18.603" LastActivityDate="2015-05-20T14:42:18.603" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14901" PostTypeId="1" AcceptedAnswerId="14903" CreationDate="2015-05-20T15:09:20.463" Score="7" ViewCount="6920" Body="&lt;p&gt;How would a test pilot determine the MTOW of an aircraft. Does the manufacturer predict this value? &lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="8079" LastEditDate="2015-06-06T23:33:10.210" LastActivityDate="2015-06-06T23:33:10.210" Title="How is Maximum Take Off Weight determined?" Tags="&lt;takeoff&gt;&lt;flight-planning&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14902" PostTypeId="2" ParentId="14898" CreationDate="2015-05-20T15:26:21.283" Score="11" Body="&lt;p&gt;A lot depends on how low you are and what aircraft you're flying, but any low-level flight has some risks and difficulties. Here are some, I'm sure there are others:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the aircraft loses power you have much less time and distance available to execute a forced landing, and your choice of landing sites will be more limited&lt;/li&gt;&#xA;&lt;li&gt;You can't see as far ahead so it's more difficult to look out for obstacles and &lt;a href=&quot;http://en.wikipedia.org/wiki/Pilotage&quot; rel=&quot;nofollow noreferrer&quot;&gt;pilotage&lt;/a&gt; may also be more difficult in some circumstances&lt;/li&gt;&#xA;&lt;li&gt;You may accidentally break the law on minimum safe flying height because the terrain changes too quickly, you don't see an obstacle or town until it's too late etc.&lt;/li&gt;&#xA;&lt;li&gt;There's a greater risk of collision with terrain or obstacles like radio towers, especially if your aircraft is a fast one and you have less time to react&lt;/li&gt;&#xA;&lt;li&gt;The likelihood of both thermal and mechanical turbulence is higher when flying low, increasing risks of loss of control and collision with terrain and obstacles&lt;/li&gt;&#xA;&lt;li&gt;If you're &lt;a href=&quot;http://en.wikipedia.org/wiki/Scud_running&quot; rel=&quot;nofollow noreferrer&quot;&gt;scud-running&lt;/a&gt; in VMC there's a high risk of &lt;a href=&quot;https://aviation.stackexchange.com/q/9764/62&quot;&gt;entering IMC accidentally&lt;/a&gt;, which is extremely dangerous (incidentally, despite the title of that question, even instrument-rated pilots have a poor safety record when they enter IMC unintentionally)&lt;/li&gt;&#xA;&lt;li&gt;Radio reception may be poor&lt;/li&gt;&#xA;&lt;li&gt;ATC radar may not be able to see you&lt;/li&gt;&#xA;&lt;li&gt;Your engine may not operate very efficiently&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's not to say that low-level flying is always a bad idea, but it I think it does require more preparation, alertness and even local knowledge from the pilot.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-06-24T16:41:09.723" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14903" PostTypeId="2" ParentId="14901" CreationDate="2015-05-20T16:28:32.110" Score="4" Body="&lt;p&gt;Pilots do not determine the official MTOW of an aircraft. MTOW will be estimated by the manufacturer during the design of the aircraft based on the required payload of the aircraft and the design configuration. It will be adjusted based on the detail design of the aircraft to comply with regulation requirements.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=be6ffa6d87343c75e7d49e911c95ab06&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:1.0.1.3.11&amp;amp;idno=14#se14.1.25_1301&quot; rel=&quot;nofollow&quot;&gt;§25.1533&lt;/a&gt;   Additional operating limitations.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Additional operating limitations must be established as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The maximum takeoff weights must be established as the weights at&#xA;  which compliance is shown with the applicable provisions of this part&#xA;  (including the takeoff climb provisions of §25.121(a) through (c), for&#xA;  altitudes and ambient temperatures).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;MTOW affects many other aspects of an aircraft's performance. It will affect stopping distance after a rejected takeoff, takeoff performance (including engine failure), climb performance, taxi weights, and many structural aspects. MTOW will be chosen so that the requirements for all of these conditions are met. This is why new engines or winglets which improve performance will allow a higher MTOW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, as always, the pilot has the authority to set their own personal MTOW more conservatively, if they feel it is necessary for safer operation of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-20T16:28:32.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14904" PostTypeId="1" AcceptedAnswerId="14906" CreationDate="2015-05-20T16:30:16.290" Score="6" ViewCount="15836" Body="&lt;p&gt;While making a flight plan, depending upon the weight of the aircraft, I'm assuming pilots determine the takeoff distance. How do they do so (is there a formula to calculate the takeoff distance)?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2017-07-04T04:41:58.390" Title="How do pilots determine the takeoff distance of an aircraft?" Tags="&lt;takeoff&gt;&lt;flight-planning&gt;&lt;flight-testing&gt;" AnswerCount="5" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14905" PostTypeId="2" ParentId="14904" CreationDate="2015-05-20T16:50:45.013" Score="7" Body="&lt;p&gt;Takeoff data is calculated using performance charts and/or software.  Data input into the algorithm include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;runway condition&lt;/li&gt;&#xA;&lt;li&gt;runway slope,&lt;/li&gt;&#xA;&lt;li&gt;wind (headwind or tailwind component),&lt;/li&gt;&#xA;&lt;li&gt;takeoff weight,&lt;/li&gt;&#xA;&lt;li&gt;aircraft configuration (flaps, slats, etc)&lt;/li&gt;&#xA;&lt;li&gt;density altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The air carrier I flew for had a performance chart for every runway we operated from (all scheduled and alternate destinations) that we could reference for the max allowable takeoff weight for that runway, flap configuration, wind condition and temperature.  We didn't actually calculate the takeoff roll distance, but rather that we were below the max weight that could accelerate to V1 and stop within the distance provided by the runway in the current wind, temperature and aircraft configuration.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-05-20T16:50:45.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14906" PostTypeId="2" ParentId="14904" CreationDate="2015-05-20T16:52:57.540" Score="8" Body="&lt;p&gt;Most airplanes have a POH (Pilot Operating Handbook) with a table on aircraft distances.  &lt;a href=&quot;http://www.michiganflyers.org/aircraft/documents/77s-info.pdf&quot; rel=&quot;noreferrer&quot;&gt;Here I have included one for the C172&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ocq04.png&quot; alt=&quot;Short Field Takeoff Chart&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="6814" LastEditorUserId="1696" LastEditDate="2015-05-20T17:00:53.183" LastActivityDate="2015-05-20T17:00:53.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14907" PostTypeId="2" ParentId="14894" CreationDate="2015-05-20T16:59:13.453" Score="19" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/14897/1696&quot;&gt;As ratchet freak noted&lt;/a&gt;, the boneyard is still active because planes are still being scrapped. One reason specific to the &lt;a href=&quot;http://www.dm.af.mil/units/amarc.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;AMARC&lt;/a&gt; in Tuscon is &lt;a href=&quot;http://www.amarcexperience.com/ui/index.php?option=com_content&amp;amp;view=article&amp;amp;id=14&amp;amp;catid=9&quot; rel=&quot;nofollow noreferrer&quot;&gt;the B-52 aircraft still being scrapped for arms reduction treaties&lt;/a&gt;. Planes may also be taken for use as targets, training aids, or even to be &lt;a href=&quot;http://www.amarcexperience.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;returned to service&lt;/a&gt;. Even if it just seems like the planes are sitting there idle, the boneyard also serves as a huge collection of available spare parts that is continuously being used to supply the aircraft that are still in service.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Typically controlling over 4,200 aircraft as well as many other types of military equipment, AMARG works very hard in promoting itself as not just a 'Boneyard' and takes every opportunity in explaining how it operates its cost effective, tax saving operations. Many of the stored aircraft can be returned to an operational status in a short period of time and there is a continual process of anti-corrosion and re-preservation work which keeps the aircraft in a stable condition during their stay.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the purpose is not just to scrap planes, but also for storage and reuse. It's not even necessarily just for old planes; &lt;a href=&quot;http://en.wikipedia.org/wiki/Alenia_C-27J_Spartan#United_States&quot; rel=&quot;nofollow noreferrer&quot;&gt;it's been used to store brand new planes until a use is found for them&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-20T16:59:13.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14909" PostTypeId="1" AcceptedAnswerId="14912" CreationDate="2015-05-20T17:59:17.950" Score="8" ViewCount="3023" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/14727/how-do-aircraft-stall-warning-systems-work#comment34193_14729&quot;&gt;this comment&lt;/a&gt; on &lt;a href=&quot;https://aviation.stackexchange.com/questions/14727/how-do-aircraft-stall-warning-systems-work&quot;&gt;this question&lt;/a&gt; about stall warning systems, it was stated that: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You can stall at any airspeed (see &lt;a href=&quot;https://aviation.stackexchange.com/q/2903/62&quot;&gt;this question&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/6366/62&quot;&gt;this&lt;/a&gt; one) and in any attitude, only the AoA is important because that's what causes the airflow to separate from the wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why, then, does the &lt;a href=&quot;http://www.michiganflyers.org/aircraft/documents/77s-info.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 172's POH&lt;/a&gt; (Page ii or 2 of 422) list stall &lt;em&gt;speed&lt;/em&gt;, not stall &lt;em&gt;AoA&lt;/em&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CZutr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CZutr.png&quot; alt=&quot;http://i.stack.imgur.com/CZutr.png&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can understand how flying slower than the listed speeds would cause a stall, but the comment above seems to imply that one could stall the plane by flying at 60, 90 or even 120 KCAS but at a high AoA. &lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-05-23T16:28:39.077" Title="Why is stall speed listed in a POH?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;aircraft-limitations&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14910" PostTypeId="1" CreationDate="2015-05-20T18:16:49.540" Score="1" ViewCount="246" Body="&lt;p&gt;Why is it that only light aircraft (like Cessnas and Cirrus') are equipped with airframe parachutes? Isn't it possible for at least slightly larger aircraft to have this feature? And isn't there a way to recover the fuselage of a relatively larger aircraft?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-20T18:16:49.540" Title="Why is it that only light aircraft are equipped with airframe parachutes?" Tags="&lt;parachute&gt;&lt;airframe&gt;&lt;airframe-parachute&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-05-20T18:44:46.943" ContentLicense="CC BY-SA 3.0" />
  <row Id="14911" PostTypeId="2" ParentId="14909" CreationDate="2015-05-20T18:18:14.823" Score="6" Body="&lt;p&gt;Most small planes do not come with an AoA sensor or display, so giving the stall AoA isn't useful to the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bulk of flying is done in the vicinity of level flight, no roll.  When in that configuration, there is a simple relationship between airspeed and angle of attack.  So the airspeed provides useful information about how the wing is likely to be doing.  It must be understood by the pilot when that relationship is no longer valid.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-05-20T18:18:14.823" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14912" PostTypeId="2" ParentId="14909" CreationDate="2015-05-20T18:57:07.660" Score="14" Body="&lt;p&gt;Those stall speeds are derived for specific conditions.  In the case of that POH those speeds assume level unaccelerated flight, 2550 lbs gross weight, standard atmosphere and no wind.  They are given as a speed rather than raw AoA because most non-aerobatic small airplanes lack AoA indications in the cockpit, while all have airspeed indicators.  A non-aerobatic airplane also spends most of its time in the part of the flight envelope where the assumptions needed to list a stall speed tend to be valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stipulation of level flight means the relative wind is fixed, thus the AoA depends only on the pitch attitude above the horizon.  For an given weight there is a relation of pitch attitude required to maintain level flight for a given airspeed.  Given these specific stipulations, you can determine the airspeed that results in the critical AoA being exceeded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If any of the criteria listed above are not true, then those published stall speeds are not meaningful to you.  You &lt;em&gt;can&lt;/em&gt; stall at any attitude and at any airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To see the true relation between airspeed and stalling you need to consult a Vg diagram.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vxxAN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The curved lines starting at 0 MPH and 0 load factor represent the stall speed for a given load factor.  The stall speed listed in PoH you quote is specifically the point noted &quot;Normal stall speed&quot; on this chart (this chart isn't for the same airplane, so the numbers will differ).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-05-20T19:05:23.837" LastActivityDate="2015-05-20T19:05:23.837" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14913" PostTypeId="1" AcceptedAnswerId="14916" CreationDate="2015-05-20T19:01:01.027" Score="7" ViewCount="3919" Body="&lt;p&gt;Emirates has this feature on many of its A380s. From what I've read, the feature decreases the amount of runway an aircraft uses after landing. It also helps the aircraft achieve a certain exit way. Is this feature unique with only Aibus aircraft? How is it set up on an aircraft and how does BTV work?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-20T20:33:24.400" Title="What is Brake To Vacate (BTV)?" Tags="&lt;landing&gt;&lt;runways&gt;&lt;airbus&gt;&lt;airbus-a380&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14914" PostTypeId="1" CreationDate="2015-05-20T19:16:26.460" Score="5" ViewCount="516" Body="&lt;p&gt;I want to calculate the lift generated by a number of out-of-plane staggered wings but I don't think a valid approach is to simply use superposition and add the sum of the lift of all the wing's in isolation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard of Munk's stagger theorem but am unsure of it's implications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the implication of Munk's theorem is that there is a limit to the amount of downwash and thus lift that can be generated by staggered wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets do an example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can calculate the lift force generated by a single planar wing as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L=\frac{1}{2}\rho V^2SC_L$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $\rho$ is air density, $V$ is free-stream velocity and $C_L$ is the finite wing lift coefficient, which is a function of the wing geometry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if I have say 5 staggered wings, is this statement:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L=5\times\frac{1}{2}\rho V^2SC_L$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;valid?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I know that the pressure distributions over the different wings will interact wing each other, but my question assumes that the wings are separated sufficiently far away from each other that this effect is negligible. Or is this interaction of pressure distribution a result of the stagger theorem?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will appreciate any light being shed on this subject. &lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="19" LastEditDate="2016-07-14T08:00:18.767" LastActivityDate="2016-07-14T08:00:18.767" Title="How is the lift generated by a number of out-of-plane staggered wings calculated?" Tags="&lt;lift&gt;&lt;fluid-mechanics&gt;&lt;multi-wing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14915" PostTypeId="2" ParentId="14899" CreationDate="2015-05-20T19:27:37.223" Score="4" Body="&lt;ol&gt;&#xA;&lt;li&gt;The noise is created by sparks caused by static electricity. As the aircraft flies through the air, it picks up electrons from the air molecules. This extra charge will want to flow back into the air to equalize the charge. Small gaps in the conductive path on the aircraft will cause sparks to form. These sparks cause noise on radio frequencies, which can be picked up by the aircraft radios.&lt;/li&gt;&#xA;&lt;li&gt;The static sparks will cause noise on the aircraft radios, sometimes a &lt;a href=&quot;http://www.lightaircraftassociation.co.uk/engineering/TechnicalLeaflets/Mods%20and%20Repairs/TL%203.14%20Radio%20Interference.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;crackling sound&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;li&gt;Aircraft use &lt;a href=&quot;https://aviation.stackexchange.com/q/2720/1696&quot;&gt;static wicks&lt;/a&gt; on trailing edges to allow the charge to equalize. If components are electrically bonded well, static electricity should not be noticeable, other than under &lt;a href=&quot;http://en.wikipedia.org/wiki/St._Elmo%27s_fire&quot; rel=&quot;nofollow noreferrer&quot;&gt;certain circumstances&lt;/a&gt;. The wicks are fixed and not telescopic but of course can be removed if replacement is needed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-05-20T19:27:37.223" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14916" PostTypeId="2" ParentId="14913" CreationDate="2015-05-20T19:29:08.327" Score="10" Body="&lt;p&gt;According to the Airbus website, Brake to Vacate is a feature installed on newer A-380s and also on the new A-350XWB that allows the pilot to select which runway exit s/he needs to use, and the system will brake hard enough, but just hard enough, to slow the plane to taxi speed by that turnoff.  This minimizes time on the runway.  The following quote is from the Airbus website.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Brake to Vacate allows pilots to select the appropriate runway exit during the approach to landing, and regulates the aircraft’s deceleration after touchdown – enabling it to reach any chosen exit at the correct speed under optimum conditions, no matter the weather and visibility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To my knowledge, Airbus is the only aircraft manufacturer to incorporate this feature - to date.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This feature does not reduce the amount of runway the aircraft uses.  Maximum Braking is still maximum braking.  It does however, optimize the braking so that the aircraft gets to the taxiway intersection sooner (doesn't brake too hard too soon, keeping speed up) and also prevents overshooting the intersection requiring a relatively slow taxi to the next turn off.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-05-20T20:33:24.400" LastActivityDate="2015-05-20T20:33:24.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14917" PostTypeId="1" AcceptedAnswerId="14919" CreationDate="2015-05-20T19:29:38.227" Score="4" ViewCount="611" Body="&lt;p&gt;How is a waypoint marked? Is there a ground station present at that waypoint? And how are these waypoints named?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-21T16:38:36.577" Title="Are there ground stations at the waypoints a pilot may fly to?" Tags="&lt;instrument-flight-rules&gt;&lt;navigation&gt;&lt;waypoint&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14918" PostTypeId="2" ParentId="14909" CreationDate="2015-05-20T19:33:21.320" Score="6" Body="&lt;p&gt;Cessna 172s don't have an AoA indicator or gauge and even today most light aircraft still don't, although you can &lt;a href=&quot;http://www.aircraftspruce.com/menus/in/angleofattackindicators.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;add them&lt;/a&gt; to some models and the &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2014/July/29/FAA-wants-angle-of-attack-systems-in-GA-aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA would like more aircraft to have them&lt;/a&gt;. So in the absence of an AoA instrument, airspeed is used as a rough proxy, assuming 'normal' flight conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crudely put, if your C172 is flying at a more or less steady 110kts then the AoA is low and you have a lot of 'reserve' before you stall; if you're flying at 60kts then it's high and you have only a little reserve. This is why watching your airspeed closely on final approach is essential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But because airspeed is only a proxy for AoA, it isn't a completely accurate way to know how close you are to a stall. Changing the load factor (roughly, the G force on the aircraft) changes the stall speed but not the critical AoA, which always remains the same (18° is commonly mentioned for light aircraft, but that's an approximation). The diagram in &lt;a href=&quot;https://aviation.stackexchange.com/a/14912/62&quot;&gt;@casey's very useful answer&lt;/a&gt; shows this clearly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, note that &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a88061fd2a273994e657697c46935fcd&amp;amp;mc=true&amp;amp;node=se14.1.23_149&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 23.49&lt;/a&gt; says that light aircraft must stall at a calibrated airspeed of 61kts or less, there's no mention of AoA.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-05-20T19:33:21.320" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14919" PostTypeId="2" ParentId="14917" CreationDate="2015-05-20T19:52:50.777" Score="11" Body="&lt;p&gt;Ground based radio navigation (VOR, VORTAC, LORAN, NDB) by necessity have ground stations to handle generation, amplification and broadcasting the signals used for navigation.  Here is an example of what a VOR station looks like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WrqyH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sub&gt;&quot;Table Rock VOR&quot; by ZabMilenko - Own work. Licensed under CC BY 3.0 via Wikimedia Commons - &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Table_Rock_VOR.jpg#/media/File:Table_Rock_VOR.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://commons.wikimedia.org/wiki/File:Table_Rock_VOR.jpg#/media/File:Table_Rock_VOR.jpg&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Waypoints that represent these stations will have ground facilities underneath them, but they are the minority of waypoints.  Most waypoints are defined as a distance along a radial from one of these stations, so there will be no ground station below them.  Other waypoints are lat/lon fixes provided by GPS, so there are no stations below them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind, no matter if there is a ground station or not below a waypoint, their presence is not important to how navigation is performed.  Waypoint passage will be noted by needles, to/from indicators, DME mileage changing, or by a points along a magenta line on a map display.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;VOR stations are often named by their location e.g. the VORTAC in San Antonio, TX is named &quot;San Antonio (SAT)&quot;.  Others are named for regional things, e.g. &quot;Ranger (FUZ)&quot;, &quot;Cowboy (CVE)&quot; and &quot;Maverick (TTT)&quot; all located in Dallas, TX named after their major sports teams (baseball, football and basketball respectively)&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-05-20T20:58:31.630" LastActivityDate="2015-05-20T20:58:31.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14920" PostTypeId="1" AcceptedAnswerId="14921" CreationDate="2015-05-20T20:06:00.733" Score="13" ViewCount="3268" Body="&lt;p&gt;The great-circle route from Western Europe to, say, Japan involves putting in a lot of miles above Russia, for example like this (London Heathrow&amp;ndash;Tokyo Narita; map from gcmap.com).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YIUaE.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would routes like that have been possible during the days of the Soviet Union or would civilian planes have had to take a more circuitous route, flying south of the USSR and maybe even avoiding the Warsaw Pact countries, too?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware that at least some of Soviet airspace was prohibited which, for example, led to the Soviet Air Force shooting down &lt;a href=&quot;https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007&quot; rel=&quot;noreferrer&quot;&gt;Korean Air Lines flight&amp;nbsp;007&lt;/a&gt;. Presumably, the route shown in the map would be prohibited, since it goes over the &lt;a href=&quot;https://en.wikipedia.org/wiki/Kola_Peninsula&quot; rel=&quot;noreferrer&quot;&gt;Kola Peninsula&lt;/a&gt;, where the Northern Fleet is based and &lt;a href=&quot;https://en.wikipedia.org/wiki/Novaya_Zemlya&quot; rel=&quot;noreferrer&quot;&gt;Novaya Zemlya&lt;/a&gt;, a major nuclear weapons test site.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="62" LastEditDate="2015-05-20T20:07:49.647" LastActivityDate="2015-05-21T15:19:56.403" Title="Were civilian aircraft allowed to overfly the Soviet Union?" Tags="&lt;airline-operations&gt;&lt;aviation-history&gt;&lt;soviet-union&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14921" PostTypeId="2" ParentId="14920" CreationDate="2015-05-20T20:27:28.347" Score="13" Body="&lt;p&gt;During the Cold War, Soviet airspace was very restricted to other countries. Flights from the US often had to follow &lt;a href=&quot;http://en.wikipedia.org/wiki/Polar_route&quot; rel=&quot;nofollow noreferrer&quot;&gt;polar routes&lt;/a&gt; to Asia and Europe that avoided entering Soviet airspace. The end of the Cold War allowed &lt;a href=&quot;http://www.spacedaily.com/news/arctic-00b.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;new routes to be used&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hoTL9.png&quot; alt=&quot;Polar Routes Map&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Polar_route#/media/File:PolarRoute.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flights to the USSR were allowed on a limited basis, often in conjunction with service by &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroflot&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeroflot&lt;/a&gt;. &lt;a href=&quot;http://enroute.aircanada.com/en/articles/postcard-from-moscow&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Canada had the first service (via Copenhagen) from North America in 1966&lt;/a&gt;. Some flights were allowed to cross the USSR (&lt;a href=&quot;https://www.jal.com/en/history/history/age_81-90.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;JAL started in 1985&lt;/a&gt;) but &lt;a href=&quot;http://www.aeroflot.ru/cms/en/new/857&quot; rel=&quot;nofollow noreferrer&quot;&gt;would often stop on Moscow&lt;/a&gt;. Otherwise, Anchorage was a typical stop on such a route. International relations may have improved since the Soviet era, but even today &lt;a href=&quot;http://www.businesstravelerusa.com/news/russia-to-ban-overflying-by-eu-airlines&quot; rel=&quot;nofollow noreferrer&quot;&gt;not every airline gets permission to overfly Russia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The strict policies are the reason that flights such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007&quot; rel=&quot;nofollow noreferrer&quot;&gt;Korean Air Lines flight 007&lt;/a&gt; were shot down when deviating from these routes, and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mathias_Rust&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight of Mathias Rust to Moscow&lt;/a&gt; was a big deal.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-05-21T15:19:56.403" LastActivityDate="2015-05-21T15:19:56.403" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14922" PostTypeId="2" ParentId="14914" CreationDate="2015-05-20T21:55:29.713" Score="2" Body="&lt;p&gt;Munk's theorem describes that when moving streamwise direction staggered wings AND keeping the circulation distribution (so changing incidence) the induced drag is kept constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not saying anything about lift (although can be obtained from circulation) and other drag components. What you are describing can't be derived from Munk's theory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difficulty is that one lifting surface modifies the pressure field around itself, having another wing affected by that pressure field will modify the pressure field on both wings affecting each other. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That situation is a complex aerodynamic situation, and very likely (so far I don't know) there is not analytical solution. You will need to use semi-empirical models like this &lt;a href=&quot;https://www.esdu.com/cgi-bin/ps.pl?sess=unlicensed_1150520215346czk&amp;amp;t=doc&amp;amp;p=esdu_81023a&quot; rel=&quot;nofollow&quot;&gt;ESDU&lt;/a&gt; or a simple panel method calculation. But it is not straight forward to calculate lift.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-05-20T21:55:29.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14923" PostTypeId="2" ParentId="14904" CreationDate="2015-05-20T22:01:53.257" Score="5" Body="&lt;p&gt;The previous answers are indeed correct; I will take it one step farther up the stack, though, and make a point that may have been unclear and addresses an assumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot doesn't calculate take-off distances; they are looked up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned, external data sources are used. The manufacturer of the aircraft, based upon their own math and the results of real-world-testing, is the authoritative source. Once it's in the operating handbook, you can be confident of those numbers (and, in fact, shouldn't second-guess them without a bloody good reason). As was also mentioned, some operators do their own testing; these results then go into the operating handbook, and the pilot is then expected to be able to count on those numbers as long as they follow the same procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most important aspects of flight is consistency; given the same external conditions, all aircraft of a particular model and particular takeoff weight should perform very similarly. This is more than just minimums. In the case of a broken instrument, whatever is being measured by the broken instrument can usually be inferred from other instruments. An example would be airspeed; if your airspeed indicator is broken, but you know your engine RPM and know that you're not climbing or descending, then you should always be about the same airspeed given that engine speed. A Cessna 172S would always be very near 120kts at 2400rpm at 2200 pounds weight. This consistency is what allows those numbers to be recovered and depended upon. (pulling numbers from head; the point is that you should be able to go into ANY Cessna 172S and expect the same performance as long as the plane has been properly maintained).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is also true of many other critical aspects of an aircraft's performance. Climb rates, fuel consumption, rate of change-of-direction in a turn... these numbers all have to be accurate, as they can mean the difference between making the runway and becoming a news story.&lt;/p&gt;&#xA;" OwnerUserId="8564" LastActivityDate="2015-05-20T22:01:53.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14924" PostTypeId="2" ParentId="14820" CreationDate="2015-05-20T22:07:21.790" Score="-2" Body="&lt;p&gt;Regarding noise of propellers at speeds close to sound barrier, you may have a look at the F-84 'Thunderstreak', propeller version video in YouTube, https://youtu.be/UFhSzReWTgs it has contra-rotating propellers, and is probably one of the fastest airplanes with this arrangement ever, the video discusses the development and findings of a contra-rotating propeller in a fighter flying close to Mach 1; at any speed, the aim of having contra-rotating propellers I guess is reducing the effect of torque that will tend to make the airplane turn in the opposite direction as the propeller, along the propellers axis, in a centrally placed, single engine airplane, a propeller rotating in a clockwise direction, looking from behind, will indice a force making the fuselage turning in the opposite direction, also the vortex and other changes in air column induced by the propeller may have an influence on control elements, such as the rudder&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-08-19T15:24:33.057" LastActivityDate="2015-08-19T15:24:33.057" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14926" PostTypeId="2" ParentId="14894" CreationDate="2015-05-21T00:23:37.627" Score="8" Body="&lt;p&gt;To tack on to &lt;a href=&quot;https://aviation.stackexchange.com/a/14907/6919&quot;&gt;@fooot's answer&lt;/a&gt; as far as aircraft reuse is concerned, AMARG also prepares aircraft for potential &lt;a href=&quot;https://www.fbo.gov/index?s=opportunity&amp;amp;mode=form&amp;amp;tab=core&amp;amp;id=5eb87803ec11e19bae7e3f874b88d0fa&quot; rel=&quot;nofollow noreferrer&quot;&gt;foreign military sales&lt;/a&gt;.  From an &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_21-54.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA circular&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The U.S. military normally retires aircraft to Davis-Monthan Air Force Base in Tucson, Arizona to be stored indefinitely, cannibalized, scrapped, or restored to service at a later date. Surplus U.S. military aircraft are generally not sold directly to private U.S. operators without congressional approval. &lt;strong&gt;However, U.S. military aircraft may be exported via foreign military sales programs or other agreements&lt;/strong&gt;.  (emphasis mine)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://books.google.com/books?id=ZVvKAgAAQBAJ&amp;amp;pg=PA136&amp;amp;dq=tall%20tom/rivet%20table&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=byRdVdeqL4qGsAX-koHIDg&amp;amp;ved=0CDEQ6AEwAA#v=onepage&amp;amp;q=tall%20tom%2Frivet%20table&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;This C-130&lt;/a&gt; lived there for three years prior to being sold to Botswana.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough, many aircraft stored there are actually in better and &lt;em&gt;more modern&lt;/em&gt; condition than the state in which the US Air Force flew them.  I knew a civilian assigned there who was the back seat test pilot for &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-4&lt;/a&gt;s after they received the necessary avionics upgrades in order to be attractive to foreign governments.&lt;/p&gt;&#xA;" OwnerUserId="6919" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-05-21T00:23:37.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14927" PostTypeId="2" ParentId="14778" CreationDate="2015-05-21T01:00:39.063" Score="4" Body="&lt;p&gt;I'm not sure where you got your info from, but here is what I know of the Multiscan radars from Collins and Honeywell:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multiscan displays precipitation from the highest tilt to the lowest so if the cloud is dense enough, even if it's a low level cloud, it will still cause returns. Keep in mind - just because the clouds are cumulus doesn't mean it has enough density to cause the WX-Radar to display any returns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're talking about the dark-cockpit-concept, then yes, at certain high altitudes, the clouds will not show on the radar. This is because the OEMs want us pilots to only see what will pose a potential risk of turbulence and safety while at that particular altitude. If you want to see what's directly underneath your aircraft, the radar should be set to manual mode. However, this only happens during cruising at high altitudes. &lt;/p&gt;&#xA;" OwnerUserId="8566" LastActivityDate="2015-05-21T01:00:39.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14928" PostTypeId="2" ParentId="14914" CreationDate="2015-05-21T04:10:24.867" Score="3" Body="&lt;p&gt;It depends on the vertical distance between the wings. Munk's theorem only covers the effect of their horizontal distance (in flow direction) and says it doesn't matter (in inviscid flow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your statement is correct if this distance is infinitely high (and the atmosphere has constant density over altitude). Only then there is no interference between the separate wings and their combined lift is the sum of the lift of every isolated wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other end of the scale, all wings together will just have the lift of a single wing if they are not separated at all. This is trivially easy to prove, but not practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For distances between the two extremes, lifting line theory gives you a good answer when the distance is not small. Below that, viscous effects will start to dominate the picture, and if the wings are separated only by something similar to the wing's thickness, they will impede the flow between the wings, making the combination appear as one blunt object to the outer flow, with consequences like flow separation and the collapse of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you move the wings apart by more than their chord length, you will get practical solutions where the wings will produce more lift than a single one and even have lower induced drag than a single wing creating the same lift force. However, a distance sufficient to make interference negligible will mean that the struts between the wings will become long and heavy, so their mass cannot be neglected. I would expect that there is an optimum of lift minus mass which is somewhere around a vertical distance of one to three chord lengths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, literature on the topic is more concerned with reducing drag, so the closest I could find is a work by Ilan Kroo &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960023622.pdf&quot; rel=&quot;nofollow&quot;&gt;on non-planar lifting systems&lt;/a&gt;. Using the solutions for biplanes will not give an answer to your question, because every wing interfers with every other, so adding a fourth and fifth wing to a triplane will reduce the lift of the triplane, but will in sum increase lift.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="19" LastEditDate="2015-05-21T06:55:18.587" LastActivityDate="2015-05-21T06:55:18.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14929" PostTypeId="1" AcceptedAnswerId="14931" CreationDate="2015-05-21T04:21:40.957" Score="8" ViewCount="3566" Body="&lt;p&gt;In a recent &lt;a href=&quot;http://aviationweek.com/defense/software-cut-fuel-supply-stricken-a400m&quot; rel=&quot;nofollow noreferrer&quot;&gt;news article&lt;/a&gt; on an Airbus A400M crash, it has the following line:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sources have told Aviation Week that aircraft MSN23, destined for Turkey, featured new software that would trim the fuel tanks, allowing the aircraft to fly certain military maneuvers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I understand what &lt;a href=&quot;https://aviation.stackexchange.com/questions/164/what-does-the-term-trimming-most-commonly-mean-in-aviation&quot;&gt;trimming&lt;/a&gt; is, but what does it mean to &lt;strong&gt;trim the fuel tanks&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="789" LastEditorUserId="14897" LastEditDate="2019-09-26T16:50:11.577" LastActivityDate="2019-09-26T16:50:11.577" Title="What is trimming the fuel tank?" Tags="&lt;fuel-tanks&gt;&lt;trim&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="14930" PostTypeId="1" AcceptedAnswerId="14939" CreationDate="2015-05-21T04:37:37.300" Score="6" ViewCount="2370" Body="&lt;p&gt;When at a towered airport and instructed to make &quot;&lt;em&gt;left pattern for runway 3,&lt;/em&gt;&quot; am I supposed to wait for the base leg turn until tower clears me for landing?  This seems to be the norm, but I can't find anything in the FAR/AIM to indicate what is acceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: I often get confused when in the downwind pattern and I hear something like this: &quot;&lt;em&gt;123X, tower, you are #2 for runway 3, following a Cessna on final.&lt;/em&gt;&quot;  Does this mean I should turn base and follow the Cessna?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know the correct answer is to ask ATC to clarify, but it would be ideal if this were spelled out in the AIM.&lt;/p&gt;&#xA;" OwnerUserId="7177" LastEditorUserId="572" LastEditDate="2015-05-21T07:33:51.890" LastActivityDate="2021-02-10T05:38:24.837" Title="When to turn base at towered airport?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;phraseology&gt;&lt;traffic-pattern&gt;&lt;aim&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14931" PostTypeId="2" ParentId="14929" CreationDate="2015-05-21T04:54:16.503" Score="9" Body="&lt;p&gt;Just like normal trimming. However trim the fuel tank use &lt;strong&gt;aft fuel tank&lt;/strong&gt; to achieve the trimming effect. Fuel is pumped between main tank and aft tank to shift CG around to a desire position during flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel tank trimming has additional benefit of keeping the airplane in &quot;clean&quot; configuration, creating less drag compare to normal trimming.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="7532" LastEditDate="2015-05-21T11:25:57.853" LastActivityDate="2015-05-21T11:25:57.853" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14932" PostTypeId="2" ParentId="14930" CreationDate="2015-05-21T07:55:48.820" Score="1" Body="&lt;p&gt;I am Australian, but I can't see why these procedures would differ greatly between our countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to your first question is no. In the absence of airport-specific published procedures, you do not need to wait for tower clearance to turn base, however you must tell them that you are commencing the turn. Usually once you tell them that you're turning base you are given a landing clearance. The exception is when you are specifically asked to report before turning base - it is not uncommon for tower to ask you to report when ready for the base leg, in which case you must not turn until cleared. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding your second point, if I take it exactly as you have presented it here that is a traffic information message only, with no clearance. The same procedures as above apply. However if you are told that you're following traffic in the pattern, you must not turn base unless you have identified the other aircraft. Accidents have been caused by the trailing aircraft 'cutting in front of' the aircraft in front. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-05-21T07:55:48.820" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14933" PostTypeId="1" CreationDate="2015-05-21T08:17:09.477" Score="9" ViewCount="4957" Body="&lt;p&gt;I've noticed that there appear to be many ways to read of a checklist between aircraft types and operators. The task and work division confuse me:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In some cases it appears to be entirely managed by the Pilot Not Flying [PNF], while in some cases the Pilot Flying [PF] is involved.&lt;/li&gt;&#xA;&lt;li&gt;For the latter case, the response from PF seems to be 'checked' some of the time while in others there is a verbal feedback on the state of that control.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I guess this is a question between Standard Operating Procedures, but &lt;strong&gt;is there a best-practice to reading off checklists that is suggested to be followed&lt;/strong&gt; as suggested by EASA or the FAA for instance?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Extra Thing: It would be great if somebody could elaborate on how a checklist actually would be worked through in practice like the one below with who says and does what.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/okOMC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-22T06:54:02.607" LastActivityDate="2015-05-22T07:53:58.480" Title="Is there a best-practice method to work through a checklist?" Tags="&lt;pilots&gt;&lt;checklist&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14934" PostTypeId="1" CreationDate="2015-05-21T08:18:45.970" Score="7" ViewCount="7209" Body="&lt;p&gt;Recently I came across a airfoil improvement called a 'Gurney flap', see image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xyKEr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9CHVO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't really understand the working principle of a Gurney.&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Gurney_flap&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Gurney flap increases lift by altering the Kutta condition at the trailing edge. The wake behind the flap is a pair of counter-rotating vortices that are alternately shed in a von Kármán vortex street.In addition to these spanwise vortices shed behind the flap, chordwise vortices shed from in front of the flap become important at high angles of attack.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't understand how the flap could generate vortices in front of the flap.&#xA;Wikipedia states the following effects:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Gurney flap increases the maximum lift coefficient ($C_{L_{max}}$), decreases the angle of attack for zero lift ($\alpha_0$), and increases the nosedown pitching moment ($C_M$), which is consistent with an increase in camber of the airfoil. It also typically increases the drag coefficient ($C_d$), especially at low angles of attack, although for thick airfoils, a reduction in drag has been reported.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is it simply a ridge that stops the flow, and thereby increases the pressure at the top surface? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How come the drag is decreased for thick airfoils if it generates extra vortices?&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="524" LastEditDate="2015-05-21T11:56:07.227" LastActivityDate="2015-05-21T13:58:33.940" Title="What is the working principle of a Gurney Flap?" Tags="&lt;aerodynamics&gt;&lt;flaps&gt;&lt;fluid-mechanics&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14935" PostTypeId="2" ParentId="14933" CreationDate="2015-05-21T11:23:20.647" Score="7" Body="&lt;p&gt;The current FAA Advisory Circular dealing with SOPs in general, but only lightly touching upon checklists, is &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-71A.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 120-71a&lt;/a&gt;. It is primarily aimed at Part 119 certificate holders who conduct operations under part 121, but is also recommended for operations under Parts 91, 125, and 135. It also changes the wording from Pilot Not Flying (PNF) to Pilot Monitoring (PM) in order to reinforce the idea that he or she is not just a passenger with a better view, but an integral part of the flight crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to actual checklist usage, to the best that I've been able to find, the FAA does not issue a hard recommendation (air carrier checklists and procedures have to be approved by the FAA prior to certificate issuance anyways), but it does identify two primary methods of checklist usage: Challenge-Do-Verify (often used for abnormal and certain emergency procedures) and Do-Verify (often used for normal and time-critical emergency procedures), which relies on memorized flows followed by verification with the use of a checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1566.pdf&quot; rel=&quot;nofollow&quot;&gt;1995 Study&lt;/a&gt; issued by the FAA weighs in on the pros and cons of the two methods and surmises that, when used properly, the CDV method is less likely to result in missed items, but does allow for the fact that, in operational usage, pilots may batch items together, thus defeating the purpose of the systematic, step-by-step approach of the method.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stepping aside from the multi-crew environment, where having someone with the checklist in their hand and reading things off one by one can work quite well, my personal observation has been that, in a single-crew environment, pilots who rely on a CDV-like method (sometimes known as Read-Do) are more likely to end up falling behind in configuring their aircraft than those who use DV-like methods, assuming of course that the pilots actually know their flows and perform the verification properly (as in actually verify that everything is as it should be rather merely reading items off the list and trying to remember if they've accomplished them).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, with respect to the 'checked' vs. verbal confirmation of status, this is usually dependent on how critical and laborious the status confirmation is. An example would be with altitude setting verification, where it is not uncommon for the procedure to call for the PF to set the new altitude in the Mode Control Panel and, while pointing to it, call out the new altitude, which is then verbally confirmed by the PM. Every operator's experience and demands will be different here, but a number of best practices are recognized and the folks at the FAA, NBAA, FSF, AOPA, and many others are doing their best to publicize and promote them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See here for the FAA's &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/resources/construction_site/media/samples/Listing%20of%20InFOs.pdf&quot; rel=&quot;nofollow&quot;&gt;Industry Best Practices Reference List&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The checklist you've provided appears to be intended for multicrew operations. In this particular case, what would happen if the CDV method was to be used is that the Pilot Monitoring would read the items off one by one and the Pilot Flying would execute accordingly, verbally acknowledge doing so, the PM would quickly verify compliance and move on to the next line item.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a DV environment, the Pilot Flying would go through the flow, and call for the checklist, at which point the Pilot Monitoring would begin to read off the items, and the Pilot Flying would verify that they have been complied with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The line items that have BOTH in them are meant to be a special emphasis case in that both crew members are required to verify that the line item has been complied with, regardless of method used.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-05-22T07:53:58.480" LastActivityDate="2015-05-22T07:53:58.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14936" PostTypeId="2" ParentId="14934" CreationDate="2015-05-21T13:12:17.337" Score="1" Body="&lt;p&gt;Adding the flap to an existing airfoil increases the angle of attack of the airfoil - just draw a straight line from the leading edge to the trailing edge: after adding the flap, the trailing edge has moved down to the tip of flap. The line before and after resemble flat plates at different angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vortex in front of the flap is produced because the flow can't make the sharp right angle turn around the flap, it can't perfectly follow the geometry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The increase in CLmax should come from an associated increase in effective camber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total drag consists of skin friction drag (mostly, for an airfoil that is just &quot;thick&quot;) and pressure drag. Maybe the increase in effective camber changes the relative amounts of both, leading to a net decrease of drag.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorDisplayName="user7241" LastEditDate="2015-05-21T13:58:33.940" LastActivityDate="2015-05-21T13:58:33.940" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14937" PostTypeId="2" ParentId="14904" CreationDate="2015-05-21T13:12:52.047" Score="4" Body="&lt;p&gt;Besides using tables, aircraft manufacturers also provide a takeoff chart, like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pTKut.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chart goes from left to right:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Enter the air temperature, then go up until you met your pressure&#xA;altitude. Then proceed horizontally to the right.&lt;/li&gt;&#xA;&lt;li&gt;Follow the contour of the lines, until you meet your weight on the&#xA;x-axis. Proceed horizontally to the right.&lt;/li&gt;&#xA;&lt;li&gt;Follow the contour of the lines, until you meet your headwind (or&#xA;tailwind) component in the x-axis. There, leave the contour and go&#xA;horizontally to the right.&lt;/li&gt;&#xA;&lt;li&gt;The y-axis gives your takeoff roll distance. If there is an obstacle&#xA;50 feet at the end of the runway, follow the lines to get your&#xA;&quot;takeoff roll + clear obstacle&quot; ground distance.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Some manufacturers provide tables. Some provide charts. Some do both.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-21T13:12:52.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14938" PostTypeId="1" CreationDate="2015-05-21T13:23:59.447" Score="0" ViewCount="221" Body="&lt;p&gt;I've flown on a couple of 737's recently and noticed that the wings are quite beautiful and have a distinctive upward sweep at the wingtip, almost like a vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What advantages and what disadvantages (if any) does this type of wing provide?  I imagine there is some gain in overall stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Qx7z3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8166" LastEditorUserId="8346" LastEditDate="2015-05-21T13:49:02.633" LastActivityDate="2015-05-21T13:49:02.633" Title="What role do the winglets on the next-generation 737 play?" Tags="&lt;wing&gt;&lt;boeing-737&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-05-21T14:15:24.717" ContentLicense="CC BY-SA 3.0" />
  <row Id="14939" PostTypeId="2" ParentId="14930" CreationDate="2015-05-21T13:27:40.143" Score="5" Body="&lt;p&gt;You have a few questions here.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...downwind pattern and I hear something like this: &quot;123X, tower, you are #2 for runway 3, following a Cessna on final.&quot; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case what you will do is continue your down wind leg while scanning for the Cessna traffic, some towers may ask you to &quot;report traffic in sight&quot; in which case you will say &quot;traffic in sight&quot; when you can see the Cessna. If he is on a long final you can begin turning your base (assuming you are in a similar small plane of a similar speed) when he is on your beam (right off your wing tip). This should provide adequate spacing for you to come in properly. Keep in mind that the tower may also instruct you to do things to keep separation like &quot;123X Extend your down wind 1 mile&quot; etc.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...instructed to make &quot;left pattern for runway 3,&quot; am I supposed to wait for the base leg turn until tower clears me for landing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on where you are coming in from. I have flown into towered airports on the runway heading and simply come into the pattern on final and was cleared to land about a mile from the runway. Other wise I typically report my midfield downwind to the tower &quot;Piper 12345 Reporting Left Midfield Downwind for RW24&quot; then the tower will respond with my landing clearance or instructions to extend. While it is the towers responsibility to clear you for landing and what not, controllers are not perfect, you can continue on towards the runway in your pattern but if you have not been cleared you should go-around or ask for clearance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other situation I have been in is a case where the controller deliberately does not clear you but has  you come into the pattern and approach. This occurred while they were waiting for an IRF plan to come through for one of the regional jets waiting for departure. Since they did not know when it would come in I was instructed to continue my pattern and would be cleared on final if they did not need to get the jet out. However I was explicitly told I would be cleared on final so I knew what to listen for.         &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-05-21T14:09:40.160" LastActivityDate="2015-05-21T14:09:40.160" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14940" PostTypeId="2" ParentId="14938" CreationDate="2015-05-21T13:29:57.170" Score="0" Body="&lt;p&gt;The wing tips calling as &quot;sharklet&quot; at Airbus A/Cs and &quot;winglet&quot; at Boeing A/Cs. It reduces the tip vortex and helps to prevent from airflow seperation at wing tips. It have positive effects on both fuel consumption and turbulance making. Negative effect of the additional part is increase of the drag coefficent but you can keep it negligible againts the positive effects.&lt;/p&gt;&#xA;" OwnerUserId="8484" LastEditorUserId="8484" LastEditDate="2015-05-21T13:35:23.183" LastActivityDate="2015-05-21T13:35:23.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14941" PostTypeId="1" CreationDate="2015-05-21T14:09:06.237" Score="1" ViewCount="843" Body="&lt;p&gt;I'm an engineer working in the civil aviation industry. Currently my company is preparing to make some placards. I've downloaded the drawings from Airbus. A drawing calls up the material of AD400 TV25/3881/83. I've seen the original OEM placard and I remember it's luminescent (it's located next to the emergency door). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've searched &quot;AD400&quot; and &quot;TV25/3881/83&quot; as the keyword on Google but found nothing useful. I think it might be the spec of the material, but what it really is and where I can get it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will be greatly appreciated if someone can tell me more info on this material. It would be much better if someone can tell me where I can buy this material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update:&#xA;Below is how the placard looks like (a screenshot taken from the drawing):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/HYDlV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The diamond 12 calls up the material of AD400 TV25/3881/83. Also the drawing says the base material is &quot; MAKROFOL-E&quot;. I know &quot;MAKROFOL&quot; is a kind of PC film and it's a trademark of Bayer, but I didn't find this material on the website of Bayer either.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/CmGHL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8570" LastEditorUserId="8570" LastEditDate="2015-05-21T15:07:48.950" LastActivityDate="2015-05-21T17:52:57.993" Title="What material is used to make luminescent placard on civil aircraft?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;&lt;airbus&gt;&lt;security&gt;&lt;cabin-design&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ClosedDate="2015-05-21T21:06:27.560" ContentLicense="CC BY-SA 3.0" />
  <row Id="14943" PostTypeId="2" ParentId="14941" CreationDate="2015-05-21T14:32:25.077" Score="1" Body="&lt;p&gt;I don't know what exactly &lt;code&gt;AD400 TV25/3881/83&lt;/code&gt; is, but if you are talking about a sign like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oHo8S.jpg&quot; alt=&quot;Luminescent Sign&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to be plastic and &lt;a href=&quot;http://www.larchfield-aerospace.com/placard-kits.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Larchfield&lt;/a&gt; sells them. This material &lt;code&gt;AD400 TV25/3881/83&lt;/code&gt; could very well be a type of plastic, but I don't know about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, you can contact companies which make or sell them (Larchfield or &lt;a href=&quot;http://www.nimbusaviation.com/#!luminescesent/c2537&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; or &lt;a href=&quot;http://www.aeroaid.com/interiors/decals-placards.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt;) to get more reliable information.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-21T14:32:25.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14944" PostTypeId="1" AcceptedAnswerId="14949" CreationDate="2015-05-21T14:34:20.067" Score="18" ViewCount="43722" Body="&lt;p&gt;Why is it that a plane as big as the C-17 (the A400M is slightly smaller though) use turboprops instead of turbofans? Both aircraft seem to have the same purpose and are both capable of landing at short runways. So why does the A400M have turboprops?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to know why two very large planes have different propulsion systems.&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="287" LastEditDate="2015-05-25T01:09:26.523" LastActivityDate="2018-02-22T11:46:06.313" Title="Why does an aircraft as big as the Airbus A400M use turboprops?" Tags="&lt;military&gt;&lt;turboprop&gt;&lt;turbofan&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14945" PostTypeId="1" CreationDate="2015-05-21T14:41:40.687" Score="7" ViewCount="1703" Body="&lt;p&gt;I am interested in historic fuel prices;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much did Avgas cost in 1940?&lt;/p&gt;&#xA;" OwnerUserId="8572" LastEditorUserId="19" LastEditDate="2016-07-14T08:00:49.283" LastActivityDate="2016-07-14T08:00:49.283" Title="How much did Avgas cost in 1940?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14946" PostTypeId="2" ParentId="14944" CreationDate="2015-05-21T14:50:49.207" Score="25" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Both aircraft seem to have the same purpose&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RAF see the C17 as a strategic airlifter, the A400 is seen as a tactical airlifter replacing the turboprop C130.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strategic airlifters are more likely to make longer, higher-altitude journeys. Where jets are more fuel efficient. They are more likely to operate between airports with concrete runways where FOD is less of an issue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tactical airlifters are more likely to make shorter, lower-altitude journeys of the sort where turboprops are more efficient. They are more likely to operate between smaller airfields where FOD may be more of an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.thinkdefence.co.uk/2011/02/the-future-of-the-raf-15-tactical-transport/&quot;&gt;ThinkDefence&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://militaryaircraft-airbusds.com/aircraft/a400m/a400mabout.aspx&quot;&gt;Airbus&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.raf.mod.uk/rafbrizenorton/equipment/a400matlas.cfm&quot;&gt;RAF&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some &lt;a href=&quot;http://planes.axlegeeks.com/compare/134-139/Airbus-A400M-vs-Boeing-C-17-Globemaster-III&quot;&gt;random internet website&lt;/a&gt; alleges the fuel costs in \$ per Nautical mile are 19.63 for A400 and 88.14 for C17. They don't say for what mission profile. At a minimum, this illustrates that there is some motivation for matching engine types to expected mix of mission types.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8tfh2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The similar sized AN-70 also uses turboprop engines, illustrating that this choice is not unusual for this sized aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Kaag.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-05-21T16:32:08.580" LastActivityDate="2015-05-21T16:32:08.580" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14947" PostTypeId="2" ParentId="14891" CreationDate="2015-05-21T15:41:21.113" Score="7" Body="&lt;p&gt;I've never heard of this on a 737. The last rows in a DC-9/MD-80 series is where I seen this the most.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest solution is for the flight crew to set the cabin temperature control to not be full cold on a humid day. Just a little heat will cut down on the condensation being developed while sitting at the gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an interesting article on moisture in the airplane, though it is not specific to the gasper vent rain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/m/m01/index.html&quot;&gt;http://www.boeing.com/commercial/aeromagazine/aero_05/m/m01/index.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some larger aircraft have dehumidifiers, but as the Boeing article states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dehumidification systems (ground-based or onboard) are effective at removing moisture but are not cost effective. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-05-21T15:41:21.113" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14949" PostTypeId="2" ParentId="14944" CreationDate="2015-05-21T16:15:50.120" Score="25" Body="&lt;p&gt;This answer needs some background information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What became the A400M started as the Future Large Aircraft or FLA in 1983. Airbus was worried what to do with their engineers after work on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot;&gt;A320&lt;/a&gt; was completed, and the next projects, soon to be called TA9 and TA11 (TA for Twin Aisle; they would eventually mature into the A330 and A340), were still far, far away. So the idea of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Transall&quot;&gt;Transall&lt;/a&gt; follow-up was dreamed up to keep Airbus busy, and the engines for this plane would help &lt;a href=&quot;http://en.wikipedia.org/wiki/Snecma&quot;&gt;Snecma&lt;/a&gt; to fund the development of their next engine after the &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_CFM56&quot;&gt;CFM56&lt;/a&gt;. Yes, the FLA started life with four turbofans!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the European military did not like to have turbofans on something that should have the shortest &lt;a href=&quot;http://en.wikipedia.org/wiki/Balanced_field_takeoff&quot;&gt;field length&lt;/a&gt; requirements possible, and especially their desire for the new transport aircraft to backup under its own power made them to demand turboprops. So in the late Eighties the FLA was converted to turboprops. These were to use the core of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Snecma_M88&quot;&gt;M88 engine&lt;/a&gt;, so Snecma would be happy with the new configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This project went through many ups and downs in the quarter of a century between its start and the first flight of the A400M, and many of the sometimes ugly details should better never be mentioned …&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-15T20:51:15.233" LastActivityDate="2016-02-15T20:51:15.233" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14950" PostTypeId="2" ParentId="14944" CreationDate="2015-05-21T16:34:07.077" Score="10" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/14946/1696&quot;&gt;As RedGrittyBrick showed&lt;/a&gt;, the aircraft are certainly similar in external dimensions, with the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A400M_Atlas&quot; rel=&quot;nofollow noreferrer&quot;&gt;A400M&lt;/a&gt; being a bit smaller than the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-17&lt;/a&gt;. However, the differences are in what the aircraft are designed for. The C-17 is designed to carry heavy cargo long distances, while the A400M is designed to carry lighter cargo shorter distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-17 is powered by 4 turbofan engines which can together produce 160,000 lbf of thrust. The A400M is powered by 4 turboprop engines that can together produce 44,000 shp, which will come out to probably less than 30,000 lbf. Though both types of engines lose power with altitude, the turboprop will also lose more power with speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference in power corresponds to a difference in the weights of the two aircraft. The C-17 MTOW is 585,000 lb, while the A400M MTOW is 310,852 lb. The max payload weight is similar: 170,900 lb for the C-17, and 81,600 lb for the A400M. The C-17 is about twice as heavy and can carry twice the payload as the A400M. The C-17 also offers a larger cargo area, with 1.5 m extra width and 3.7 m extra length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the similar size, both aircraft can carry a similar amount of troops. The C-17 carries up to 134 and the A400M carries up to 116. However, the C-17 can only carry 102 paratroops, while the A400M can still accommodate 116. The A400M can also accommodate 66 stretchers, while the C-17 can only accommodate 36. This illustrates that the A400M is designed to carry lighter cargo such as personnel, but the C-17 isn't really more capable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As RedGrittyBrick also mentioned, this leads to a difference in roles. The powerful turbofans on the C-17 can carry a lot of payload, but they need longer distances to make up for the higher fuel consumption. The C-17 can fly 2,420 nmi with max payload, and the A400M can fly 1,780 nmi. Similarly, the C-17 can fly 5,610 nmi with paratroopers, while the A400M can fly 3,450 nmi with a 20-tonne payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xFnff.png&quot; alt=&quot;Payload-range for C-17, A400M, and C-130J&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/military/read.main/72415/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Based on Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-21T16:34:07.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14952" PostTypeId="1" AcceptedAnswerId="14957" CreationDate="2015-05-21T16:38:49.763" Score="52" ViewCount="14585" Body="&lt;p&gt;In today's age, when dogfights are simply a relic from the past, why do manufacturers keep on increasing their aircraft maneuverability, in order to make them better dogfighters. It is more understandable if they were to make stealthier or more efficient fighters, but when the dogfight is extinct, why make planes even more agile and maneuverable? &lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="1696" LastEditDate="2018-04-24T14:08:13.600" LastActivityDate="2018-04-24T14:08:13.600" Title="Why do fighter aircraft manufacturers still focus on making their planes more dogfight-worthy?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;stealth&gt;&lt;dogfighting&gt;" AnswerCount="7" CommentCount="7" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="14953" PostTypeId="2" ParentId="14933" CreationDate="2015-05-21T16:43:18.523" Score="4" Body="&lt;p&gt;There are really two aspects to your question: Operational usage and Design usage. The two are closely related, but let's look at them separately:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Operational Usage&lt;/strong&gt;&lt;br&gt;&#xA;From an operational standpoint the absolute best way to use a checklist is in a multi-person crew situation: Actions are performed (&lt;a href=&quot;https://aviation.stackexchange.com/questions/12707/what-is-the-difference-between-a-flow-and-a-checklist&quot;&gt;usually with the help of flows&lt;/a&gt;), then the checklist is read and each item is verified, ideally by a different crewmember than the one who performed the action.&lt;br&gt;&#xA;This use of checklists provides independent and redundant verification that all required actions have been performed, and you find it in a lot of other industries that use checklists: The operating procedures at my day job are regulated by a different three-letter &quot;F&quot; agency, but our critical procedures still have checklists, and they're used as I described. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a single-pilot environment the same logic holds: You generally want to use the checklist to verify (&lt;em&gt;check&lt;/em&gt;) that things have been completed rather than using it as a &quot;to-do list&quot;. This makes it a verification step and introduces redundancy into your procedures.&lt;br&gt;&#xA;(If you can stand Jason Miller's slightly-cheesy intro music he discusses this in &lt;a href=&quot;http://podbay.fm/show/84885574/e/1129820400&quot; rel=&quot;nofollow noreferrer&quot;&gt;one of his podcast episodes&lt;/a&gt;, it's worth a listen.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Design Usage&lt;/strong&gt;&lt;br&gt;&#xA;This is one that doesn't get discussed often, but &lt;a href=&quot;https://aviation.stackexchange.com/questions/14933/is-there-a-best-practice-method-to-work-through-a-checklist#comment34699_14933&quot;&gt;ratchet freak made mention of it&lt;/a&gt;: Your checklist should be logically designed so you can move through it in an organized way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The checklist you posted is an excellent example of this: A flight will proceed through that checklist top-to-bottom, left-to-right (the first things you do will be &quot;Before Start&quot;, and the last things you do will be &quot;Securing&quot;), and within each category the checklist should also proceed in a logical order (for example good preflight checklists usually take you around the plane in an organized path.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no shortage of &lt;em&gt;badly designed&lt;/em&gt; checklists (manufacturer's checklists tend to be among the worst in this regard: A Piper or Cessna preflight checklist in the POH usually has you making 4 or 5 trips around the plane checking things in seemingly-random order).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The process of designing a good checklist is an interesting Human Factors problem - there's a lot of literature on it but it's way out of scope for this site. The usual solution to badly designed checklists is that pilots get frustrated and write our own.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-21T16:43:18.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14954" PostTypeId="2" ParentId="14952" CreationDate="2015-05-21T16:44:39.747" Score="19" Body="&lt;p&gt;While dogfighting may be extinct in Afghanistan, its certainly not extinct in Russia, China, Europe, India, etc.  Nations do not arm to fight the current threat, they arm to discourage possible future threats and project power abroad.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-05-21T16:44:39.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14955" PostTypeId="2" ParentId="14952" CreationDate="2015-05-21T17:00:23.437" Score="21" Body="&lt;p&gt;Dogfighting isn't dead.  Even though generation 4.5/5 airframes have great missile capability and stealth, there are times when there is no substitute for bullets.  Close quarter gun fire is pretty much immune to chaff and flares.  Being able to maneuver into position to engage another aircraft with guns is essential in many circumstances and training for that will likely be a fundamental part of flight training for a long time, so, I doubt that manufacturers will stop developing more maneuverable jets even though electronic/computer systems are playing a larger part in air to air combat.&lt;/p&gt;&#xA;" OwnerUserId="8166" LastActivityDate="2015-05-21T17:00:23.437" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14956" PostTypeId="2" ParentId="14941" CreationDate="2015-05-21T17:52:57.993" Score="0" Body="&lt;p&gt;As you've surmised, it's a type of polycarbonate.  It's also probably impregnated (or reverse-coated) with a phosphorescent compound so that it glows for a while after being exposed to light. (In the old days it would probably have been radioluminescent - phosphorescent compounds doped with radium or similar so they always glow, even when they haven't been exposed to light - but that's generally frowned upon these days.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could certainly order the material from Bayer if you need it in bulk (for making your own signs), or order &lt;a href=&quot;https://www.inventables.com/technologies/glow-in-the-dark-and-clear-reverse-laserable-acrylic-sheet&quot; rel=&quot;nofollow&quot;&gt;similar materials&lt;/a&gt; which are probably cheaper. (Be aware that other materials may not meet flammability or environmental/safety requirements for aerospace applications though: In particular many of these sheets are PVC, which would produce some nasty byproducts in a post-crash fire!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking at this for aerospace purposes (for example building a cabin simulator for flight crew training) I'd do as Farhan suggested and contact one of the companies that produces replacement placards and just buy them - it's the ultimate level of realism, and way easier than making them yourself. If you're looking to make placards for your own aircraft out of similar material they might also be able to source it for you (or be willing to do a custom placard run, for a price).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-05-21T17:52:57.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14957" PostTypeId="2" ParentId="14952" CreationDate="2015-05-21T18:00:41.327" Score="95" Body="&lt;p&gt;That same thinking, &quot;dogfighting is dead&quot;, got the USAF and USN in serious trouble in Vietnam. The U.S. Armed Forces were convinced that the next major war would be against the Soviet Union directly, in theaters including Europe, Alaska and Canada, and as a result, fighter designs succeeding the very successful Sabre and Super Sabre day fighters used in Korea began emphasizing standoff capabilities, believing the aerial threat would come from various classes of nuclear bomber, calling for fast, long-range missile-armed interceptors as a counter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That war, thankfully, never materialized. Instead, the U.S. was pulled into more or less another Korea, a proxy war fought between Soviet-supplied and trained Communist forces against a U.S.-backed fledgling democracy. The big, heavy U.S. F-4 Phantom interceptor and F-105 Thunderchief light bomber, neither of which had internal guns, found themselves facing the older like-minded successor to the MiG-15s they faced in Korea, the MiG-17, coupled with the MiG-21 close-range interceptor. Instead of the long-range standoff air war the USAF was built for, US pilots were ambushed at close range by guns and infrared missiles, resulting in a piss-poor 2:1 kill/death ratio in aerial engagements, compared to the 14:1 ratio they enjoyed in Korea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The result was increased attention paid to &quot;air combat maneuvering&quot;, and an emphasis on this style of combat in the next generation of fighters adopted by the U.S. military. The F-14 and F-15, though intended to bring back dogfighting (and they did), turned out to be big, fast interceptor-style fighters like their predecessors, that still only had a clear advantage in BVR engagements. So a group of USAF generals, seeing what its allies had been doing with the F-5 Tiger that the Joint Chiefs had more or less passed on (a few trainers, a few aggressor planes, but no combat adoption), commissioned the LWF competition, which would produce the F-16 and F-18 lightweight multirole fighters with an emphasis on the close-quarters maneuverability that the Communist powers never really forgot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 splits the difference between the F-15 and F-16's air combat strategies, producing a heavier but highly maneuverable fighter that excels at air combat at any range (but is so expensive that so far the USAF have only deployed them in situations where they would never face any real threat). The F-35, however, is rapidly becoming a disappointment; compared even to the F-16 or F-15E it will replace, it &quot;can't climb, can't turn, and can't run&quot;, and the A variant is the only one with an internal cannon (which carries only 182 rounds of ammunition compared to the F-22s 480, the F-15's 650 and the F-16's 510); the STOVL B variant and the Navy's C variant won't have guns at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In today's military theater, the U.S. enjoys &quot;air supremacy&quot;; we're fighting largely paramilitary forces with practically zero air to air capability. Tomorrow's theater, however, may be quite different. Diplomatic relationships with a number of Russian-supplied nations including Russia itself are souring day by day, and the U.S. could easily find itself drawn into conflicts over Taiwan, the Korean peninsula, India/Pakistan, the Ukraine, etc, where they'd face militaries fielding Russian jets purpose-built to mix it up at visual range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, while the U.S. hasn't directly fought a conflict against a serious air threat since Vietnam, there are a lot of potential near-future conflicts in which they would get their chance, facing the Sukhoi PAK-FA or Chengdu J-20 with skilled Chinese or Russian pilots at the stick. Even if these fighters aren't fielded in mass numbers, the U.S. would still face the Russians' direct answers to U.S 4th and 4.5-generation fighters, including the MiG-29 and Su-27/30/33.  Many variants of these were specifically designed to out-maneuver the U.S. F-15, F-16 and F-18 (which would likely be the first jets in-theater), and which would still be a match for the F-22 in a visual-range &quot;furball&quot;.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T16:58:57.850" LastActivityDate="2015-07-23T16:58:57.850" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="14958" PostTypeId="2" ParentId="14952" CreationDate="2015-05-21T18:05:35.987" Score="12" Body="&lt;p&gt;Some good answers here, in complement to which I would like to submit a very interesting &lt;a href=&quot;http://www.vmi.edu/uploadedfiles/archives/adams_center/essaycontest/20042005/higbyp_0405.pdf&quot;&gt;paper&lt;/a&gt; (&lt;a href=&quot;http://pogoarchives.org/labyrinth/11/09.pdf&quot;&gt;alternate link - pdf!&lt;/a&gt;) I came across on the promise vs. reality of BVR combat, which has been predicted to replace dogfighting since the 50s, if not 40s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, history has shown that despite all advances, battlefield realities have consistently forced aircraft into close-range situations where traditional ACM capability still matters, so manufacturers have to take that into account if they hope to sell their aircraft. The only reason dogfighting is extinct in Afghanistan is because insurgents there have no aircraft of their own to operate. Operations elsewhere have demonstrated the continued relevance of having a platform that can maneuver when it has to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is, however, a reverse side to the coin in that, while maneuverability and thrust-to-weight ratios remain important, we may be hitting a plateau in terms of how much more that capability is being improved. So-called &quot;supermaneuverability&quot; is becoming a fairly ubiquitous feature in most modern dedicated air superiority fighters (e.g. F-22, T-50, Super Flanker series, the Eurofighter Typhoon in its air superiority configuration, etc.) but the levels of agility currently on display have often been first showcased more than 20 years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the meantime, other features such as stealth, supercruise, passive and low-probability-of-intercept sensor suites, data links, helmet-mounted sights and off-boresight launch capability for missiles, along with a massive push towards improving pilots' situational awareness have seen tremendous advances in the past 20 years and, to my mind, say a good deal about what the air forces of the world (i.e. the customers) perceive to be the elements that will give them an edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, dogfighting capability is still regarded as an essential capability, but only time will tell if its importance will diminish relative to other elements.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="1961" LastEditDate="2015-05-21T20:12:26.267" LastActivityDate="2015-05-21T20:12:26.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="14959" PostTypeId="1" AcceptedAnswerId="14969" CreationDate="2015-05-21T18:58:57.693" Score="13" ViewCount="4052" Body="&lt;p&gt;The situation that I came up with is merely hypothetical. Say a pilot was unable to land right after the runway threshold, for whatever reason it may be - a crosswind, etc - but was determined to land the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that most pilots would abort the landing and go around but say this one decides to land. However, it is too close to the end of the runway to stop just by using brakes, spoilers, and the thrust reversers. Could this type of landing (in an emergency) be achieved and by using the parking brakes what would happen if a pilot actually used the parking brakes to slow down?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="64" LastEditDate="2015-06-26T17:08:19.127" LastActivityDate="2016-07-10T13:28:14.730" Title="What would happen if a pilot were to use the parking brakes after touchdown in order to slow down?" Tags="&lt;landing&gt;&lt;emergency&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14960" PostTypeId="2" ParentId="14959" CreationDate="2015-05-21T19:10:18.993" Score="8" Body="&lt;p&gt;There is some nice info &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/326691/&quot;&gt;on this thread&lt;/a&gt; and it seems that the parking brakes on large airliners actuate the hydraulic systems as would be expected (unlike in some cars where the parking brake is its own mechanism). It also alludes to the fact that some emergency landing procedures would call for the use of the parking brake. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a related note, it should be mentioned (and I don't know enough to know if this is actually possible in a large airliner) but I would think you would not want to lock the wheels to the point that they lost traction. This would actually reduce your braking ability. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="774" LastEditDate="2015-05-21T22:47:17.887" LastActivityDate="2015-05-21T22:47:17.887" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14962" PostTypeId="2" ParentId="14102" CreationDate="2015-05-21T20:46:46.747" Score="2" Body="&lt;p&gt;Two makes that immediately came to mind on seeing the picture were Pfalz and Albatross. Most &quot;Albatri&quot; had trapezoidal wings instead of square, though, and most Pfalz D.IIIs which would have had the aerodynamic shape were known for a much larger engine protrusion from the top of the fuselage (and a much lower top wing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about the French origin of the plane; French (and British) biplanes of the era typically used radial engines, with the Se.5 being a notable exception (and the SE5 wasn't nearly so aerodynamic-looking).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My best guess is, maybe, a DFW C.V:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1O57P.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These were WWI reconnaissance aircraft that came in several different engine configurations as the war progressed. Austria's Aviatik firm made some of these as the C.VI, as well as some very similar designs like the C.1, C.II and C.III. Here's a picture of the C.III; body is similar but the lower wing is shorter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ttRmr.jpg&quot; alt=&quot;http://images.memorix.nl/nda/thumb/400x400/28ec75e2-5302-bc10-4bfb-b547f734680f.jpg&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radiator in front of the top wing on the C.V is a little larger here than in your picture, but it's possible, even probable, that the radiator configuration also varied (could be as simple as a 90* rotation). Wing shape and strut configuration are very similar. Your picture may have been a &quot;war prize&quot; delivered to the French after the Armistice, and de-militarized (disarmed, markings removed) for civilian use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's another C.V that looks a little more like yours but without the nose cone, but this makes it look like a much bigger plane than is depicted in your shot:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5ShDy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-21T20:57:20.980" LastActivityDate="2015-05-21T20:57:20.980" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14963" PostTypeId="1" CreationDate="2015-05-21T20:59:56.850" Score="4" ViewCount="1158" Body="&lt;p&gt;First, to clarify, I'm not looking for nightmare stories here. I'm not curious about the fears of passengers but rather about what's actually noticeable for them. It's pretty clear that passengers not flying too often tend to be afraid during turbulence. But, I suppose, very few of them ever experienced a stall or similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, reading about &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;crashes like the one of AF447&lt;/a&gt; where a pilot only very late in the emergency situation re-enters the cockpit, I'm curious about why that is. I've never been on a plane during a stall, let alone an airliner. Don't passengers (and thus a pilot outside the cockpit) experience a stall as something very unusual, dramatic event? As another example, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Germanwings_Flight_9525&quot; rel=&quot;nofollow noreferrer&quot;&gt;crash of 4U9525&lt;/a&gt; which was, as I understand it, a very &quot;common descent&quot;: could a passenger even notice a difference between the upcoming crash and, say, an emergency landing at a close airport that the pilot just didn't have the time to explain beforehand?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given &quot;weird feelings&quot; during flights, often related to turbulence which is not at all dangerous -- can a passenger &quot;feel&quot; the difference between those, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot; rel=&quot;nofollow noreferrer&quot;&gt;controlled flight into terrain&lt;/a&gt;, and an imminent crash?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I disagree with closing this questions as a duplicate of &lt;a href=&quot;https://aviation.stackexchange.com/questions/170/what-things-can-a-passenger-look-out-for-to-indicate-an-emergency&quot;&gt;What things can a passenger look out for, to indicate an emergency?&lt;/a&gt;. I was not looking for how passengers could intercept with flight management. Let's make it more concrete with the AF447 example then:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Wikipedia, about half a minute after the problem of wrong speed indication occurred, the aircraft went into stall. Another three minutes later the now returned pilot realized the stall only after he was made aware of the PF pulling up the whole time. Given this example, does a stall with an A330 feel so much &quot;normal&quot; that even a highly experienced pilot couldn't &quot;feel&quot; the missing lift? Will the passengers have thought the flight was still normal at this point?&lt;/p&gt;&#xA;" OwnerUserId="8509" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-01-30T21:44:16.167" Title="Could passengers realize a possible emergency?" Tags="&lt;emergency&gt;&lt;passenger&gt;&lt;af447-accident&gt;" AnswerCount="2" CommentCount="7" ClosedDate="2015-05-22T03:16:32.027" ContentLicense="CC BY-SA 3.0" />
  <row Id="14964" PostTypeId="2" ParentId="14963" CreationDate="2015-05-21T21:05:40.483" Score="6" Body="&lt;p&gt;One of the survivors (a passenger) of &lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR82-08.pdf&quot; rel=&quot;nofollow&quot;&gt;Air Florida Flight 90&lt;/a&gt; was a Private Pilot and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...Stiley, a pilot himself, said he realized that something was wrong as the plane headed down the runway. He said there was still snow and slush on the wings and he remembered wishing he could get off the plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://abcnews.go.com/GMA/story?id=125881&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1467" LastEditDate="2015-05-22T06:12:43.753" LastActivityDate="2015-05-22T06:12:43.753" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14965" PostTypeId="2" ParentId="14959" CreationDate="2015-05-21T22:06:51.310" Score="-3" Body="&lt;p&gt;Actual &lt;a href=&quot;http://en.wikipedia.org/wiki/Rejected_takeoff&quot; rel=&quot;nofollow&quot;&gt;RTO&lt;/a&gt; (rejected take off) is a certification test that airplane manufacturer must perform succesfully.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this test the airplane must reach decision speed and abort take-off. When aborting take-off, the pilot should stop the airplane without using the thrust reverses and fire should not be extended to the airplane within 5 minutes (enough for passenguers to evacuate). This test shall be performed using the airplane at MTOW&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, your question addresses a lighter airplane (MLW &amp;lt; MTOW) and thrust reverses can be used. So the answer is yes, it can use the breaks and will work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I provide you &lt;a href=&quot;https://www.youtube.com/watch?v=lUMuOyMTQ8Y&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; the video showing the actual test performed by the A340.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-05-21T22:06:51.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14966" PostTypeId="2" ParentId="14952" CreationDate="2015-05-21T23:43:31.620" Score="3" Body="&lt;p&gt;Haven't you seen Independence Day?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's always better to be prepared for a category of threat than to write it off. Why teach a soldier hand-to-hand fighting when he has an &lt;em&gt;assault rifle&lt;/em&gt;? Because you don't want to lose a perfectly good soldier when he gets surprise-jumped and doesn't have the time or space to bring his rifle to bear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, the recent Defense spending trend in the U.S. is very large, &lt;strong&gt;very expensive orders&lt;/strong&gt; of a particular vehicle. Those numbers are &lt;strong&gt;much easier to sell&lt;/strong&gt; when that vehicle can (on paper) fulfill multiple roles. Just like in business, you're going to have some marketing wizard who's only job is to secure the biggest budget possible for your pet project, and his goal is to have an endless bullet-list of features to attract those dollars.&lt;/p&gt;&#xA;" OwnerUserId="8577" LastActivityDate="2015-05-21T23:43:31.620" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="14967" PostTypeId="2" ParentId="14883" CreationDate="2015-05-21T23:45:06.120" Score="0" Body="&lt;p&gt;Descending from Class A airspace on approach to an airport, a commercial airliner will, in my experience, often pitch down slightly. It can be somewhat unnerving, especially as the engines will throttle down around the same time, but the nose-down is typically very shallow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether a pilot continues to nose-down on final depends on the aircraft, the airport and the wind conditions. It's often a practical requirement to nose down at the runway in a high crosswind landing, in order to minimize the sideways slip produced by the crosswind as well as to traverse the layer of air containing the crosswind as quickly as possible.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-03T22:18:43.277" LastActivityDate="2015-08-03T22:18:43.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14968" PostTypeId="2" ParentId="14883" CreationDate="2015-05-22T01:17:01.677" Score="4" Body="&lt;p&gt;To add a bit of historical background, the argument used to rage as to whether you should &quot;control altitude with pitch and speed with power&quot; or &quot;control altitude with power and speed with pitch.&quot; I always felt (and still do, though I'm long retired) that adhering to a hard line either way was a bit silly. Obviously you can use either to change either, within limitations of course. I don't know what current thinking is on the subject. In the end it's a matter of energy management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There used to be at least one special case where you would want to change both altitude and speed by using pitch alone for a bit. On the 747-200 with certain engines, when starting a descent from high altitude (like the high 30s up to the max operating altitude), the recommendation was to start the descent by putting the nose down first and waiting until the airspeed started increasing before reducing power, thus avoiding the embarrassment of a possible high altitude flameout. My guess is that with modern engines and FADEC, this kind of thing is no longer an issue.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="4474" LastEditDate="2015-05-23T20:03:31.930" LastActivityDate="2015-05-23T20:03:31.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14969" PostTypeId="2" ParentId="14959" CreationDate="2015-05-22T01:27:56.410" Score="16" Body="&lt;p&gt;This question appears to have an implicit assumption: that the parking brake would provide more deceleration than is available from normal braking. This is not generally the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A much greater worry for pilots than insufficient braking is actually excessive braking - to the point that the wheel locks up and skids. A skidding tire provides much less braking than a rolling one, and also quickly acquires a flat spot. Even on dry pavement, maximum braking would require an anti-skid system to remain effective; consider &lt;a href=&quot;http://www.flightglobal.com/news/articles/american-757-back-at-work-after-anti-skid-failure-319950/&quot;&gt;a 757&lt;/a&gt; and &lt;a href=&quot;http://theaviationist.com/2014/03/10/mig-29-antiskid-failure/&quot;&gt;a Mig-29&lt;/a&gt;, each of which blew out their tires when their anti-skid systems failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that in small planes without complex braking systems, the parking brake merely maintains the pressure that is in the brake lines at the time it's applied. The parking brake would have no effect if the pilot were not already on the brakes, and would not be able to add any additional braking than the pilot could otherwise apply.&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-05-22T01:27:56.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14970" PostTypeId="2" ParentId="14963" CreationDate="2015-05-22T02:54:50.060" Score="6" Body="&lt;p&gt;While it's certainly possible to come up with scenarios, either historical or suggested by imagination, where passengers would or could know that &quot;something isn't right,&quot; the number of scenarios where &quot;false positive&quot; conclusions (taking as an emergency something that in fact, isn't) and &quot;false negatives&quot; (not knowing about something emergent actually going on) will probably be far greater.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All sorts of things can come up that will be fairly transparent to the passengers, until a pilot gets on the PA and announces that they'll be diverting to a more immediate landing: loss of a hydraulic system or navigation system, a medical emergency on board, some types of electrical malfunctions, etc etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, many of the things that produce the most noticeable cues that &quot;something isn't right&quot; are simply turbulence... it doesn't feel right because it isn't particularly normal, but it's no emergency, just a rough ride.  With a LOT of experience, one &lt;strong&gt;&lt;em&gt;might&lt;/em&gt;&lt;/strong&gt; be able to tell the difference between a jolt of turbulence (or wake turbulence) and, say, the momentary yaw associated with an engine shutdown, but who has &quot;experience&quot; riding through multiple engine shutdowns these days?  It's too rare an event for many people to have been through more than zero, let alone two or three.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, while some things are clearly not normal -- flames coming out of an engine, smoke in the cabin, fuel streaming out of a wing, etc, these sorts of things are really uncommon.  I once asked our safety department what was the most common emergency that they saw in all the safety reporting, and the answers were #1 diverts of an ill passenger, and then #2 issues with flaps/slats not extending or retracting correctly (either actual issues, or false indications of trouble).  And everything else was pretty far behind those two causes.  So, if you weren't close by the medical event, your chances of knowing about it (besides the PA) are slight, and unless you &lt;em&gt;really&lt;/em&gt; know what to look for, the chance of spotting an abnormal flap/slat configuration are pretty remote as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I wouldn't assume that very many aircraft emergencies have symptoms that are immediately visible to the passengers.  Some will, but many won't, and not everything that seems unusual is a sign of any looming problems.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-22T02:54:50.060" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14971" PostTypeId="1" AcceptedAnswerId="15001" CreationDate="2015-05-22T08:28:01.513" Score="31" ViewCount="13113" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14952/why-do-fighter-aircraft-manufacturers-still-focus-on-making-their-planes-more-do&quot;&gt;This excellent question&lt;/a&gt; addresses the role of dogfighting in modern aerial warfare. However it seems that most ACM concentrate on maneuvering into shooting position. &lt;strong&gt;Why don't combat aircraft have rear-facing weaponry?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even WW-II bombers had rear-, side-, and downward cannons, albeit manned. Could a small electronically-controlled cannon be added to the stern dorsal part of a combat aircraft, for shooting rearward? I've personally seen remote-operated &lt;a href=&quot;http://en.wikipedia.org/wiki/FN_MAG&quot; rel=&quot;noreferrer&quot;&gt;FN MAGS&lt;/a&gt; on vehicles, the whole system seems to weigh on the order of 100-150 KG including hundreds of rounds. The vehicle-mounted systems took up about a cubic meter or so of space, but a purposed-designed system could probably take up less than half that, and probably shave off a good portion of the weight as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could a computer not point a barrel at a vehicle with a relative velocity approaching 0 and shoot, even in a +Mach 1 wind &lt;em&gt;in the direction of the target&lt;/em&gt;? It may be enough to just get a few bullets in, shotgun style. The Uzi rifles famously &lt;em&gt;don't&lt;/em&gt; shoot straight, they make a cone of bullets. Perhaps this cone, if aimed in the general direction of an aggressive aircraft, might be enough to either disable it or get it off your tail. A short barrel will make a wider cone, perhaps the rear-facing weapon could have an very short barrel. ACMs such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pugachev%27s_Cobra&quot; rel=&quot;noreferrer&quot;&gt;Cobra maneuver&lt;/a&gt; seem to imply that there are a finite number of angles from which attack is most likely, the weapon could be limited in angular range to those angles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure that piloting an aircraft while trying to avoid being shot is difficult enough, so I wouldn't assume that such a system would be of much help on a single-seat aircraft. However, in a dogfight presumably the ROI or navigator could operate the guns while the pilot does the aviation.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2020-01-11T18:40:36.227" Title="Why don't combat aircraft have rear-facing weapons?" Tags="&lt;military&gt;&lt;dogfighting&gt;" AnswerCount="8" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14972" PostTypeId="1" AcceptedAnswerId="14973" CreationDate="2015-05-22T09:11:42.567" Score="15" ViewCount="973" Body="&lt;p&gt;Flightradar24 has &lt;a href=&quot;https://twitter.com/flightradar24/status/601590237752664065&quot;&gt;announced few hours ago&lt;/a&gt;, that Qantas QF7 is taking off for its 13,804 km long flight and named it &lt;em&gt;the longest commercial flight (by distance)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is that correct? I was more than sure, that I heard few years ago, that current record belongs to Singapore Airlines, that has at least one commercial route of a little bit more than 14k kilometers.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="14957" LastEditDate="2017-04-23T09:07:05.627" LastActivityDate="2020-03-24T13:46:42.300" Title="What is currently the longest commercial flight in terms of distance?" Tags="&lt;aviation-history&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14973" PostTypeId="2" ParentId="14972" CreationDate="2015-05-22T09:23:42.830" Score="17" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-stop_flight#Discontinued&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, the flight you are referring to, SQ21, got discontinued in November 2013. The runner up, still from Singapore Airlines, SQ37, got discontinued one month earlier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Longest_flights#By_great_circle_distance&quot; rel=&quot;nofollow noreferrer&quot;&gt;same page&lt;/a&gt; reports that &lt;strike&gt;QF8 is the current holder of the title of &quot;longest non-stop flight&quot; and has the same destinations as today's QF7&lt;/strike&gt; as of &lt;a href=&quot;https://www.bbc.com/news/world-asia-35710969&quot; rel=&quot;nofollow noreferrer&quot;&gt;February 2017&lt;/a&gt; Qatar Airways flights 920/921, covering 14,534 km (7,848nm / 9,031mi) from &lt;a href=&quot;https://en.wikipedia.org/wiki/Doha_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Doha, Qatar (DOH/OTBD)&lt;/a&gt; to &lt;a href=&quot;https://en.wikipedia.org/wiki/Auckland_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Auckland, New Zealand (AKL/NZAA)&lt;/a&gt;, beats QF8 by about 395 NM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we instead include 1-time-only flight by a commercial airliner, the longest one has been flown in &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_distance_record#Commercial_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;November 2005&lt;/a&gt; between Hong Kong and London, as a &lt;a href=&quot;https://web.archive.org/web/20191203173757/http://www.seattlepi.com/business/article/Flight-distance-record-awaits-as-big-777-heads-to-1187040.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;demo&lt;/a&gt; by Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The title of absolute longest flight without refueling is instead held by a &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_distance_record#Non-commercial_powered_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;non-commercial flight&lt;/a&gt; done in an aircraft specifically built for the purpose.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="8282" LastEditDate="2020-03-18T12:13:26.013" LastActivityDate="2020-03-18T12:13:26.013" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="14974" PostTypeId="2" ParentId="14971" CreationDate="2015-05-22T10:23:03.667" Score="18" Body="&lt;p&gt;When in a dogfight, you cannot shoot straight ahead without moving into a position which anticipates where your adversary will be when the bullets hit him. This means you need to turn tighter, to get into his circle. When both aircraft have similar specs, this is harder than it sounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Russians once tested an idea which looked obvious at first: Svivel the gun upward, so it shoots into the circle without the aircraft needing to maneuver into the circle itself. They tested this on a &lt;a href=&quot;http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15&quot;&gt;MiG-15&lt;/a&gt;, but the results were disappointing. As soon as the gun was misaligned with the fuselage by more than a few degrees, the recoil from the gun would cause the MiG to pitch down; the last thing you need in a dogfight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lesson is easy: Shooting at an angle from a point far away from the center of gravity will cause control issues and might even be a greater danger to yourself than to your adversary. It might be that a modern &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot;&gt;FCS&lt;/a&gt; can compensate for this, but to my knowledge this has never been tried.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-05-22T10:23:03.667" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="14975" PostTypeId="2" ParentId="14971" CreationDate="2015-05-22T10:55:49.350" Score="4" Body="&lt;p&gt;Bear in mind this is all speculation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firing to the rear could be a bit optimistic; the pursuer won't be straight behind, he may be anywhere in a wide cone behind.  (How wide that cone might be, we'd need to ask someone with experience in this area!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A remotely swivelled cannon would probably be too slow to point anywhere within that cone, as the pursuer will naturally fire as soon as he has a position.  Some heavy bombers have cannon (remote or manned) to the rear, but these are unlikely to be used in fast dogfights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note most recent dogfights seem to have involved missiles, see &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_engagements_of_the_Gulf_War&quot; rel=&quot;nofollow&quot;&gt;gulf war engagements list&lt;/a&gt;.  The preferred use for cannon on fighters might be in the ability to use a non-lethal show of force against heavy bombers or spyplanes, in a cold war situation.  I recently found this mentioned while reading up about the old &lt;a href=&quot;http://en.wikipedia.org/wiki/English_Electric_Lightning&quot; rel=&quot;nofollow&quot;&gt;Lightning&lt;/a&gt; (search that link for &quot;warning shots&quot;).&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-05-22T10:55:49.350" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="14976" PostTypeId="1" AcceptedAnswerId="15033" CreationDate="2015-05-22T11:26:56.407" Score="1" ViewCount="581" Body="&lt;p&gt;Third on list of &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_distance_record#Non-commercial_powered_aircraft&quot; rel=&quot;nofollow&quot;&gt;longest non-stop, non-commercial powered aircraft's flights&lt;/a&gt; is January 10–11, 1962 flight on Boeing B-52H Stratofortress made by major Clyde P. Evely and crew. Can anyone provide any details about this flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_distance_record#Non-commercial_powered_aircraft&quot; rel=&quot;nofollow&quot;&gt;says&lt;/a&gt;, that it was a flight from Japan (Okinawa) to Spain, via Tokyo, Seattle, Fort Worth, Washington and Azores. I'm especially interested in knowing, why that way? Most (all) of today commercial flights are flying Europe to Japan / Far East the opposite way, that is through Asia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any source of information, why did that flight took the longer route? Was that specially made to break the world record or was there any other circumstances to take such decision?&lt;/p&gt;&#xA;" OwnerUserId="3230" LastActivityDate="2015-05-24T09:24:32.373" Title="Why Clyde P. / Boeing B-52H Stratofortress flight from 1962 took the longer route?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="14978" PostTypeId="1" CreationDate="2015-05-22T13:47:07.943" Score="1" ViewCount="1550" Body="&lt;p&gt;When performing a climb in a &lt;a href=&quot;http://en.wikipedia.org/wiki/SIAI-Marchetti_SF.260&quot; rel=&quot;nofollow&quot;&gt;SIAI-Marchetti SF.260&lt;/a&gt; with a Lycoming engine, the fuel pressure decreased. Why would that happen?&lt;/p&gt;&#xA;" OwnerUserId="8589" LastEditorUserId="62" LastEditDate="2015-05-22T16:49:25.993" LastActivityDate="2015-05-26T21:56:20.940" Title="Why would the fuel pressure decrease during a climb?" Tags="&lt;piston-engine&gt;&lt;fuel&gt;&lt;single-engine&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14981" PostTypeId="2" ParentId="9564" CreationDate="2015-05-22T15:37:31.990" Score="2" Body="&lt;p&gt;Any time the question is &lt;em&gt;&quot;why don't we have...&quot;&lt;/em&gt;, the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, &amp;amp; utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting a complex parachute system on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. All that extra weight has to be flown around, requiring fuel. They would need regular maintenance checks, which is another cost. And a parachute would only be useful very, very infrequently (on most planes, it would &lt;strong&gt;&lt;em&gt;never&lt;/em&gt;&lt;/strong&gt; be used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This same line of reasoning goes for &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11584/why-movable-thrusters-are-not-used-in-airplanes/&quot;&gt;why don't more airplanes have rocket thrusters&lt;/a&gt;&quot;, &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7768/why-dont-airliners-carry-radar-jamming-technology-or-missile-counter-measures&quot;&gt;why don't planes have anti-missile systems&lt;/a&gt;&quot;, &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9818/airbags-in-aircraft-is-that-just-a-military-thing&quot;&gt;why don't planes have airbags&lt;/a&gt;&quot;, and many other random items.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-05-22T15:37:31.990" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14982" PostTypeId="1" AcceptedAnswerId="14983" CreationDate="2015-05-22T15:48:30.137" Score="11" ViewCount="2693" Body="&lt;p&gt;For example, flaperons (flaps + ailerons) and elevons (elevator + ailerons), are all individual control surfaces but play the roles of two different control surfaces. What is the point of making a single control surface, undertake the functions of two?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1p9iw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-09-04T18:29:13.020" Title="What is the point of making one control surface play the part of multiple control surfaces?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;flaps&gt;&lt;ailerons&gt;&lt;elevator&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14983" PostTypeId="2" ParentId="14982" CreationDate="2015-05-22T16:01:51.710" Score="1" Body="&lt;p&gt;This is speculation, so give it the credibility it deserves....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the required aircraft performance dictates ailerons to be essentially the full length of the wing (as in the plane you pictured), there may not be sufficient room for flaps to also be as effective as needed.  So the solution is one control surface long enough to satisfy both needs.   &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-05-22T16:01:51.710" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14985" PostTypeId="2" ParentId="14982" CreationDate="2015-05-22T16:47:46.967" Score="5" Body="&lt;p&gt;Further speculation: Fewer control surfaces overall means fewer moving parts, less mechanical complexity, less weight, possibly less drag, and so forth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downside is that the control system must allow the combined control surfaces to be controlled in a way that makes sense to a pilot. This can be done mechanically, but especially in aircraft that are fly-by-wire anyway, combining the inputs in software has zero weight or mechanical-complexity cost.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-05-22T16:47:46.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14986" PostTypeId="2" ParentId="14982" CreationDate="2015-05-22T16:48:33.207" Score="13" Body="&lt;p&gt;Flaps which only extend over part of the wing will cause lift changes mainly over that part of the wing, which will result in a lift distribution over span which is far from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Elliptical_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;elliptic ideal&lt;/a&gt; once the flap is deflected. Therefore, it makes sense to move the ailerons in the same direction, especially when the inboard flaps are simple camber-changing flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to give an aircraft wing docile &lt;a href=&quot;https://aviation.stackexchange.com/questions/3484/how-is-a-wing-designed-to-be-stall-or-spin-proof&quot;&gt;stall characteristics&lt;/a&gt;, the planform should not be elliptic, but be &quot;fuller&quot; (= having more local chord than the ideal ellipse) at the wingtips. With an elliptic planform and an elliptic lift distribution, the local lift coefficient will be identical over the whole wing, and gusts might easily cause a local stall at one outer wing in slow flight. The consequence will be an uncontrollable roll, which can ruin the pilot's day when occurring close to the ground. Therefore, it is better to leave some margin by increasing local chord and adding some &lt;a href=&quot;http://en.wikipedia.org/wiki/Washout_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;washout&lt;/a&gt; towards the tips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now this wing will have an elliptic distribution only at one angle of attack. If the angle of attack is higher, the lift distribution will be fuller, and if it is lower than the &quot;elliptic&quot; angle of attack, some lift will be missing towards the tips. Both conditions will cause higher induced drag than necessary. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5018/why-and-when-to-use-flaps&quot;&gt;Flaps help by adjusting local camber&lt;/a&gt; such that if they are set correctly, the spanwise lift distribution will be much closer to the elliptic ideal than without flaps. This requires the flap schedule to make bigger deflection changes towards the root - watch any modern high performance glider change flap settings, and you will see what I mean: The flaperons will change deflection less that the inboard flaps. This has the additional benefit of leaving more margin for aileron deflections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the disadvantage of combined control surfaces: What is needed for one function is no longer available for the other function, because the maximum useable deflection range is limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the nitpickers: Please understand the term &quot;elliptic lift distribution&quot; as &quot;elliptic circulation distribution&quot;. Then all is well.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-05-22T22:46:07.353" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14987" PostTypeId="1" AcceptedAnswerId="14989" CreationDate="2015-05-22T16:58:35.630" Score="7" ViewCount="1141" Body="&lt;p&gt;I've heard that manufacturers (like Boeing and Airbus) constantly get data from their planes. So in the case of an emergency, ATC's or pilots can contact the manufacturers for assistance. How do manufacturers constantly get this data and how is it stored (cause considering the number of planes flying today, it must be a lot)?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-22T18:55:21.473" Title="How is it possible for manufacturers to constantly get data from their planes all over the world?" Tags="&lt;boeing&gt;&lt;airbus&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14988" PostTypeId="2" ParentId="14987" CreationDate="2015-05-22T17:14:12.510" Score="2" Body="&lt;p&gt;They are installed with some sensors which keep sending important data to the manufacturer. And, talking about their size, they are merely in just KBs, which is very small compared to storage the amount available even for all flights combined. Also, all information collection is automatic i.e. handled by computers so there is no problem in collecting information either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read: &lt;a href=&quot;http://www.forbes.com/sites/johngoglia/2014/03/13/aircraft-engine-monitoring-how-it-works-and-how-it-could-help-malaysia-air-370-crash-investigtors/&quot; rel=&quot;nofollow&quot;&gt;http://www.forbes.com/sites/johngoglia/2014/03/13/aircraft-engine-monitoring-how-it-works-and-how-it-could-help-malaysia-air-370-crash-investigtors/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8346" LastEditDate="2015-05-22T17:53:31.507" LastActivityDate="2015-05-22T17:53:31.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14989" PostTypeId="2" ParentId="14987" CreationDate="2015-05-22T18:22:37.803" Score="8" Body="&lt;h2&gt;How do makers get data from aircraft in flight&lt;/h2&gt;&#xA;&lt;p&gt;The data is usually transmitted using something like &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;noreferrer&quot;&gt;ACARS&lt;/a&gt; which is a system used in aircraft to transmit data in flight using underlying radio and satellite communications systems.&lt;/p&gt;&#xA;&lt;p&gt;The communications infrastructure is typically provided by large multinational companies who specialise in this job. See ARINC, SITA, Inmarsat and so on.&lt;/p&gt;&#xA;&lt;p&gt;Engine-makers and Aircraft makers often offer pro-active maintenance and support services to airlines, operators and lessors which involve their aircraft transmitting such data to the makers.&lt;/p&gt;&#xA;&lt;p&gt;For example, Airbus has &lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/airthm/&quot; rel=&quot;noreferrer&quot;&gt;AIRTHM&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Airbus Real Time Health Monitoring (AiRTHM) is an advanced service through which A380 and A350 XWB operators can receive guidance on optimised maintenance and real-time troubleshooting actions. As part of this effort, a dedicated 24/7 team takes advantage of the uplink technology to further investigate and anticipate warnings/fault consequences.&lt;/p&gt;&#xA;&lt;p&gt;The uplink technology allows real-time remote access to aircraft data parameters via the ACARS digital datalink system, enabling Airbus AiRTHM engineers to deliver maintenance and technical advice both in flight and on the ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Boeing have &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/aviationservices/brochures/AirplaneHealthManagement.pdf&quot; rel=&quot;noreferrer&quot;&gt;AHM&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;AHM sutomatically monitors, collects and transmits service levels using ACARS through the installed Aircraft Condition Monitoring System (ACMS)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Note that ACARS is a relatively low-volume data transmission system. Makers have explored other underlying communication systems as a way to transmit more data at lower cost.&lt;/p&gt;&#xA;&lt;h2&gt;How is this data stored&lt;/h2&gt;&#xA;&lt;p&gt;It is true that there is a lot of data but Boeing and Airbus are big businesses and are able to partner with major IT businesses.&lt;/p&gt;&#xA;&lt;p&gt;For example &lt;a href=&quot;http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-and-ibm-to-help-aircraft-operators-optimize-fleet-management-and-operations/&quot; rel=&quot;noreferrer&quot;&gt;IBM work with Airbus&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;“Today’s aircraft can generate up to a half terabyte of data per flight, an unprecedented volume and variety of data seen in few other industries,” said Timothy Wholey, IBM global leader for the aerospace and defense industry in its global business services unit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Note - not all data has to be transmitted in flight. A lot of data is collected and stored in the plane and only transferred when the aircraft is on the ground.&lt;/p&gt;&#xA;&lt;p&gt;Makers like Airbus and Boeing inevitably are already very heavy users of IT for aircraft design purposes. For example, &lt;a href=&quot;http://www8.hp.com/us/en/hp-news/press-release.html?id=1087760#.VV964PlVhBc&quot; rel=&quot;noreferrer&quot;&gt;Airbus use HP Supercomputing hardware&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-22T18:55:21.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14990" PostTypeId="2" ParentId="14987" CreationDate="2015-05-22T18:28:08.007" Score="0" Body="&lt;p&gt;&lt;strong&gt;Boeing&lt;/strong&gt; has a system installed in many airplanes which monitors engine health. It is called Airplane Health Management. A good presentation &lt;a href=&quot;http://www.boeing.com/features/2013/07/bca-airplane-health-mgmt-07-30-13.page&quot; rel=&quot;nofollow&quot;&gt;can be seen here&lt;/a&gt; (more info &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/aviationservices/brochures/AirplaneHealthManagement.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.boeing.com/787-media-resource/docs/AHM-overview.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airbus&lt;/strong&gt; uses &lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/airthm/&quot; rel=&quot;nofollow&quot;&gt;Airbus Real Time Health Monitoring (AiRTHM)&lt;/a&gt; which essentially does the same (more info &lt;a href=&quot;http://www.airbus.com/innovation/proven-concepts/in-fleet-support/airman/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that these systems are &lt;em&gt;not&lt;/em&gt; installed on every single airplane but are getting popular more and more.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-22T18:28:08.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14991" PostTypeId="1" AcceptedAnswerId="14995" CreationDate="2015-05-22T18:42:41.177" Score="7" ViewCount="324" Body="&lt;p&gt;I've observed this on many flight trackers; the time taken to fly from A to B is not necessarily the same as the time taken to fly back from B to A. Why is this so and what external factors besides prevailing winds (headwind going one way, tailwind the other) create this difference in time taken? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: late May 2015, per &lt;a href=&quot;http://aa.com&quot;&gt;American Airlines&lt;/a&gt;, PHL to MCO is about 15 minutes longer going south than going north, but times MIA to BDL are essentially identical in either direction.  Prevailing winds would affect both routes similarly, but the difference in times northbound vs southbound isn't the same.  Why not?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="7532" LastEditDate="2015-05-22T23:22:28.273" LastActivityDate="2015-05-23T13:22:51.643" Title="What factors besides tail/headwinds cause the time taken to fly some routes to be different from the time it takes to return?" Tags="&lt;flight-planning&gt;&lt;online-tracking&gt;&lt;flightradar24&gt;&lt;time&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="14992" PostTypeId="2" ParentId="14883" CreationDate="2015-05-22T18:50:36.217" Score="0" Body="&lt;p&gt;Whenever you track a reference in the vertical plane of your aircraft (nose to tail) it requires you to pitch up and down. &lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorDisplayName="user7241" LastEditDate="2015-05-23T12:58:42.213" LastActivityDate="2015-05-23T12:58:42.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14994" PostTypeId="2" ParentId="14952" CreationDate="2015-05-22T18:54:38.063" Score="7" Body="&lt;p&gt;The manufacturers aren't trying to increase their aircrafts maneuverability. The F-35 is far less maneuverable than the fighters it is replacing. Modern selling points include stealth, multi-role, reconfigurability, avionics, price, and data. It is all about Situational Awareness.&lt;/p&gt;&#xA;&lt;p&gt;General Hostage of USAF says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;People focus on stealth as the determining factor or delineator of the&#xA;fifth generation. &lt;strong&gt;It isn’t; it’s fusion.&lt;/strong&gt; Fusion is what makes that&#xA;platform so fundamentally different than anything else.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Lieutenant Colonel Berke says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;But the difference between a Hornet or a&#xA;Viper and the Raptor &lt;strong&gt;isn’t just the way you turn or which way you move&#xA;the jet&lt;/strong&gt; or what is the best 43 way to attack a particular problem.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;The difference is in how you think.&lt;/strong&gt;&lt;/em&gt; You work in a totally different way to garner situational awareness and make decisions; it’s all different in&#xA;the F-22. With the F-22, as will be the case with the F-35, you’re&#xA;operating at a level where you perform several functions of classic&#xA;air battle management. That’s a whole different experience that&#xA;requires a different kind of training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And from another pilot:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The whole point to fifth generation is the s&lt;strong&gt;ynergy of stealth, fusion&#xA;and complete situational awareness&lt;/strong&gt;,&amp;quot; says a veteran Air Force fighter&#xA;pilot. The point about fifth generation aircraft is that they can do&#xA;their mission anywhere - even in sophisticated integrated air defense&#xA;[IADS] environments. If you fly into heavy IADS with a great radar and&#xA;sensor fusion, but no stealth, you will have complete situational&#xA;awareness of the guy that kills you.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Maneuverability and dogfighting isn't a selling point. In fact lt.col Berke specifically dismisses it.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Moreover, the answer from KeithS seems quite off. The F-105 Thunderchief was a ground attack fighter-bomber.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;As a follow-on to the Mach 1 capable North American F-100 Super Sabre, the F-105 was also armed with missiles and a cannon; however, its design was tailored to high-speed low-altitude penetration carrying a single nuclear weapon internally. [...] During the war, the single-seat F-105D was the primary aircraft delivering the heavy bomb loads against the various military targets. Meanwhile, the two-seat F-105F and F-105G Wild Weasel variants became the first dedicated Suppression of Enemy Air Defenses (SEAD) platforms, fighting against the Soviet-built S-75 Dvina (NATO reporting name: SA-2 Guideline) surface-to-air missiles.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Of course it isn't going to be a great dogfighter. Still, it rackered up nearly 30 MiG kills. The F-4 however was an Interceptor with standoff weaponry,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[its] biggest weakness, as it was initially designed, was its lack of an internal cannon. For a brief period, doctrine held that turning combat would be impossible at supersonic speeds and little effort was made to teach pilots air combat maneuvering. In reality, engagements quickly became subsonic, as pilots would slow down in an effort to get behind their adversaries. &lt;strong&gt;Furthermore, the relatively new heat-seeking and radar-guided missiles at the time were frequently reported as unreliable&lt;/strong&gt; and pilots had to use multiple shots (also known as ripple-firing), just to hit one enemy fighter. &lt;strong&gt;To compound the problem, rules of engagement in Vietnam precluded long-range missile attacks in most instances&lt;/strong&gt;, as visual identification was normally required. Many pilots found themselves on the tail of an enemy aircraft but too close to fire short-range Falcons or Sidewinders.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So while it wasn't designed as a dogfighter, that isn't the cause of its low kill:death ratio. Politics and 60s-70s era technology was.&lt;/p&gt;&#xA;" OwnerUserId="8594" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-22T18:54:38.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="14995" PostTypeId="2" ParentId="14991" CreationDate="2015-05-22T19:24:56.900" Score="5" Body="&lt;p&gt;Sometimes, prevailing winds will account for the difference -- flights going west to east in the US will generally be scheduled for less time than flights going the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other major factor that can play is in taxi times.  If the delays waiting to get in to a gate matched the times waiting to depart at each airport, these delays would affect both legs equally, but that's not generally the case.  Most of the time, at a congested airport like Atlanta, you can generally get into the gate fairly quickly, but the delays getting airborne can be far longer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, a flight scheduled from Podunk into ATL might be scheduled for 10 minutes taxi from the gate to departure at Podunk, the flight time, and another 10 or 15 minutes to taxi in, but in the other direction they might build in 30-45 minutes of taxi time departing ATL, plus the flight time, plus 5 minutes landing until blocking in at Podunk.  Thus the leg into ATL is scheduled for flight time plus 25 minutes, while the leg from ATL is scheduled for flight time plus 35-50 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's winter time and your flight was going from BOS or PHL to MCO, another factor in addition to the potential for massive departure delays would be the need to build in time for deicing -- done before departure in PHL or BOS, but not so much leaving Orlando.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if you didn't need to deice &quot;today,&quot; then you'd probably beat the scheduled time by a good bit.  Likewise if the weather was clear and the airport had no delays.  But the mega-hub airports run so close to capacity that any little hiccup in the weather or otherwise causes delays to start building, and then you're using all of your scheduled time, and sometimes more.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-22T19:24:56.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14996" PostTypeId="2" ParentId="14982" CreationDate="2015-05-22T22:19:55.207" Score="10" Body="&lt;p&gt;Several good reasons depending on the design and intent of the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Mechanical simplicity.&lt;/strong&gt; In your case of &quot;flaperons&quot;, having a single set of control surfaces do two things decreases the number of moving parts the plane has. Simple is best; the simpler your aircraft, the less can go wrong (and the lighter it is, and when you're trying to get something off the ground, lightweight is good too). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Durability.&lt;/strong&gt; Even when mechanical simplicity isn't as much of a concern and the craft has distinct flaps and ailerons (in multiple sections), making the ailerons react to flap position as well as stick/yoke input can help normalize the forces across the wing, reducing shear moments along the wing spar and other stressed sections of the wing, decreasing the potential for fatigue and failure. Some commercial airliners, particularly Boeing designs, have rear-wing control surfaces in three sections; innermost are a set of multi-tier flaps, then in the middle are &quot;inboard ailerons&quot; which act as ailerons at cruise speed but flaps at takeoff/landing, then the &quot;outboard ailerons&quot; which are used only at low speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aerodynamics.&lt;/strong&gt; Every square inch of surface area of the plane increases drag. Designs like the V-tail reduce total surface area by eliminating an entire control surface and stabilizer from the empennage, using the remaining two as &quot;rudder-vators&quot;. This Beechcraft V35 is known as a very efficient cruiser especially at altitude (unfortunately they also have a bad rap for squirrelly roll behavior and a series of structural failures early in production, leading to their moniker of &quot;Doctor Killers&quot;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zAhVD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Stealth.&lt;/strong&gt; The YF-23, which lost the ATF competition to what would become the F-22 Raptor, used a similar rudder-vator configuration because it reduced the plane's radar cross-section compared to the 22's parallel elevators. The resulting plane was actually stealthier (and faster) than the Raptor, but less agile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5rLt5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-2 Spirit, obviously, has no tail at all, so the primary control surfaces do quadruple duty as ailerons, elevators, spoilers/air brakes, and rudder (by opening the air brake on one side or the other). The craft has separate flap systems, so the primary control surfaces are &lt;em&gt;only&lt;/em&gt; &quot;spoilaileruddervators&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/m1f8X.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Computer control.&lt;/strong&gt; The F-16 was designed with &quot;elevons&quot; instead of traditional aileron/elevator controls for a number of reasons, one of the primary ones being to reduce the required complexity of the F-16A's original analog FLCC. The only control surfaces on the wings themselves are trailing-edge flaps which are also under FLCC control and extended in any high-AOA situation. Delta-wing aircraft without canards, like the Mirage 2000, use elevons by necessity (the Rafale and Eurofighter use canard elevators but supplement them at high speeds or AOAs with the elevons).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/32afM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-04T18:29:13.020" LastActivityDate="2015-09-04T18:29:13.020" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="14997" PostTypeId="2" ParentId="14971" CreationDate="2015-05-22T22:46:57.560" Score="19" Body="&lt;p&gt;If your opponent is directly behind you, you have lost the fight. The point of basic fighter maneuvering, or BFM, is to keep your opponent off your tail and hopefully get on his. Everything you would learn as a fighter pilot centers around ensuring you would never have to use a rear-firing weapon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, visibility directly behind the pilot is typically poor; humans can't turn our heads 180 degrees, and if we could we'd be staring at the headrest behind us. A few fighters have had rear-view mirrors, typically ones with a two-piece canopy including the Eurofighter, F-15C and F-14 among others, but the one-piece bubble canopy on fighters like the F-16 and F-22 give no good place to put a mirror that wouldn't further interfere with the pilot's forward vision. Rear-view cameras would be laughed at by pilots as a waste of an MFD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cannon firing backward would also be a pretty single-purpose weapon; in a multirole fighter you might get a chance to use it to add insult to injury when pulling out of a ground run, but in all likelihood you'll either have peeled off to one side as soon as you pickled your bombs, or you'll be toss-bombing and not even overfly the target. The only real reason you'd ever fire it would be to keep someone directly behind you on their toes.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-05-22T22:46:57.560" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="14998" PostTypeId="2" ParentId="8260" CreationDate="2015-05-22T23:47:54.840" Score="3" Body="&lt;p&gt;There are few reasons an airline would sell an airworthy aircraft. As long as the aircraft can fly, it can make money. It typically comes down to pure cost-benefits and risk analysis:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;First off, if the FAA says the plane's flying days are over, then there's no decision to make; it makes one last run with a flight crew only to a boneyard like Arizona, where it will eventually be stripped for usable parts and the rest scrapped to recycle the metal. Even if the FAA will let the plane fly, the airline's insurer may take a look at the maintenance history and the problems found and say &quot;uh-uh&quot;, figuring more problems are just around the corner.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Second, even if the frame's still airworthy and insurable, it might cost more in replacement parts and maintenance to keep it that way than it's worth carrying passengers. AA finally came to that conclusion with its MD-80 fleet; the Super-80 has been out of production for over 15 years now, parts only get scarcer, and its relatively narrow fuselage increases load-in/load-out times and and reduces passenger comfort compared to its replacements like the A319 and 737 (which carry about the same passenger count in a shorter, fatter fuselage that feels roomier), meaning people were less and less likely to choose American if the plane for the flight would be a Super-80.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Third, an airline's basic strategy may change. An airline may spin off a regional subsidiary (and its Embraer puddle-hoppers), or reduce international flights (thus retiring some older 747s without replacing them). Southwest is making a more subtle change, opting for the larger 737-800 over the 300s and then 700s it had previously favored, using the larger size to get more passengers into fewer gates at the smaller or older airports it tends to service, like its primary hub at DAL which is limited to 20 total gates by the agreement that repealed the Wright Amendment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-05-22T23:47:54.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="14999" PostTypeId="1" AcceptedAnswerId="15000" CreationDate="2015-05-23T01:42:31.490" Score="12" ViewCount="2808" Body="&lt;p&gt;Why is the manufacturing process mostly done by humans, and not by robots as in case of most other industries?&lt;img src=&quot;https://i.stack.imgur.com/wOJNc.png&quot; alt=&quot;B747-8 Production Unit]![enter image description here&quot;&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=puJx6aq5i_w&quot; rel=&quot;noreferrer&quot;&gt;Video&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2017-11-16T16:29:45.420" Title="Why is the manufacturing process of an aircraft mostly manual?" Tags="&lt;aircraft-manufacturer&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15000" PostTypeId="2" ParentId="14999" CreationDate="2015-05-23T04:23:38.397" Score="19" Body="&lt;p&gt;Although robots have taken over many jobs in the process of manufacturing things like cars, airliners are much larger and more complex. In some ways it has more in common with constructing a building than assembling a vehicle. There is a much larger variety of tasks to be performed over a much larger area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, many parts of the manufacturing process are completed by robots. For example, &lt;a href=&quot;http://www.gemcor.com/wp/automation-products/wing-fastening-systems/&quot; rel=&quot;noreferrer&quot;&gt;Gemcor&lt;/a&gt; makes machines that automatically drill aircraft wings and fasten them with rivets and bolts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BHxy7.jpg&quot; alt=&quot;Gemcor riveter&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Robots are also used in &lt;a href=&quot;https://youtu.be/xK4gMDduHgA&quot; rel=&quot;noreferrer&quot;&gt;manufacturing large composites&lt;/a&gt;. You'll notice how massive these machines are, and they are only completing one task on one component. They are very good at tasks that require one or more of force, repetition, and accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, so much of the process is not economical to be done with robots. A robot specializes in one task or one type of task, while humans can do many different tasks. Many tasks involve working in tight spaces, which humans can do better than a large robot. Tasks like installing wires require dexterity as well, which humans are better at.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-23T04:23:38.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15001" PostTypeId="2" ParentId="14971" CreationDate="2015-05-23T04:59:52.990" Score="16" Body="&lt;p&gt;Machine guns were fairly effective weapons in WWII and shortly after. However, this was only because the attacking aircraft were also armed with machine guns. Even then, the fighter aircraft could be effective against not only the armed bombers, but also against the fighter escorts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bombers of the time did typically have tail gunners. However, this only resulted in a change of tactics, with fighters attacking from a different angle. Defending against one means of attack just means the attackers may choose a different attack vector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the rocket age changed all this. Modern missiles can be fire-and-forget, automatically tracking a target from many miles away. Guns aren't very effective in this type of combat. In fact, &lt;a href=&quot;https://aviation.stackexchange.com/q/8686/1696&quot;&gt;it's debated whether fighter aircraft even need a forward facing gun anymore&lt;/a&gt;. &lt;a href=&quot;http://www.defensenews.com/story/defense/air-space/strike/2015/01/07/f35-gun-on-track/21401907/&quot; rel=&quot;noreferrer&quot;&gt;The gun on the F-35 may not even be usable until after the first squadrons are operational&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high speeds, the rear-facing gun would have to overcome the forward velocity of the aircraft, decreasing its effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One could imagine something like a &lt;a href=&quot;http://en.wikipedia.org/wiki/Phalanx_CIWS&quot; rel=&quot;noreferrer&quot;&gt;CIWS&lt;/a&gt; being helpful, but the weight and size would not justify the benefit for being included on a fighter, or even a bomber. Modern aircraft have chosen &lt;a href=&quot;http://en.wikipedia.org/wiki/Electronic_countermeasure&quot; rel=&quot;noreferrer&quot;&gt;electronic defenses&lt;/a&gt; over mechanical ones. These can be lighter, easier to integrate, and are more effective in a wide variety of situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, combining the two ideas and &lt;a href=&quot;http://defensetech.org/2015/05/22/air-force-wants-to-fire-lasers-from-aircraft-by-2023/&quot; rel=&quot;noreferrer&quot;&gt;arming aircraft with lasers&lt;/a&gt; is still a possibility for the future.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-07-13T15:02:27.207" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15002" PostTypeId="1" AcceptedAnswerId="15003" CreationDate="2015-05-23T05:35:58.620" Score="19" ViewCount="4148" Body="&lt;p&gt;The cockpit of the 747 is on the upper deck, but the cockpit of the A380 is situated on the lower deck. Is there any reason (be it engineering or anything else) for the location of the cockpit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dgy5r.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-25T17:47:02.993" Title="Is there any particular reason for the cockpit of the 747 being on the upper deck?" Tags="&lt;cockpit&gt;&lt;airbus-a380&gt;&lt;boeing-747&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15003" PostTypeId="2" ParentId="15002" CreationDate="2015-05-23T06:23:44.373" Score="31" Body="&lt;p&gt;Boeing actually never expected the 747 to be so successful. They thought supersonic aircraft were the future. But Boeing knew that an aircraft the size of a 747 would be great for the cargo market. So they designed one aircraft that could be easiy converted into a cargo version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cargo 747s can literally open their nose. It is &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Nose_cargo_door_of_Boeing_747-8F.jpg/1280px-Nose_cargo_door_of_Boeing_747-8F.jpg&quot;&gt;quite impressive&lt;/a&gt;. To accomodate this, the cockpit needed to be on the upper deck. Hence the passenger version had the same requirement. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3386" LastEditDate="2015-05-23T06:37:05.083" LastActivityDate="2015-05-23T06:37:05.083" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15005" PostTypeId="1" AcceptedAnswerId="15054" CreationDate="2015-05-23T08:20:13.247" Score="4" ViewCount="969" Body="&lt;p&gt;I am studying aircraft navigation systems, as what concern autonomous navigation a compass is obviously essential, but magnetic compass is not reliable in short term maneuvers due to accelerations so it has to be stabilized by a directional gyro. What i don't understand is &lt;strong&gt;how&lt;/strong&gt; the gyro is connected to the compass and stabilizes it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern airliners is this device still used ? Is there an electronic substitute with no mechanical gyro (a part from GPS system) ?&lt;/p&gt;&#xA;" OwnerUserId="8399" LastActivityDate="2015-05-25T00:08:36.290" Title="Dead reckoning navigation: gyromagnetic compass, how it is stabilized?" Tags="&lt;navigation&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15006" PostTypeId="2" ParentId="8260" CreationDate="2015-05-23T08:45:40.897" Score="7" Body="&lt;p&gt;Answer to this question can be very conditional. Different airlines have different policies and depends on economic status of country its operating.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Some airlines have policy to retire aircraft after a fixed number of hours of operations irrespective of the condition of aircraft. They either sell it to other company our lease it out. This model of aircraft retirement prevails in company having robust operation and good flow of finances. Under these conditions retired aircraft are not UN-airworthy or unfit for flying,however they are used by small airlines and also in less developed countries.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Second Consideration on retirement of aircraft, also depends on pressurization cycles that an aircraft underwent. In big transport airlines aircraft there is pressurization system , which involves cycle of pressurization. Each cycle has impact on air- frame of aircraft. After certain number of pressurization cycles aircraft may be assume to be unfit for flying and can be retired.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Third scenario is aircraft met an serious accident and its beyond repair , hence declared un-airworthy, therefore retired.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft must meet certain parameters in terms of performance, if aircraft does not meet that criterion of performance set by civil aviation regulation authority, in this situation an aircraft has to be repaired to achieve required standard of airworthiness. In case if it cannot achieve that hence again it is retired aircraft. &lt;/li&gt;&#xA;&lt;li&gt;Time to time aircraft is inspected by civil aviation regulatory authority for the health of its components, including air frame , engines etc. In situation aircraft is declared to crossed it age to be airworthy , can also be treated as retired aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Most common criterion of aircraft retirement is fixed by air regulation authority , if they declare aircraft un-airworthy and deny to issue certificate of airworthiness. This is ultimate situation of aircraft retirement&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8604" LastEditorUserId="19" LastEditDate="2015-05-23T09:03:21.073" LastActivityDate="2015-05-23T09:03:21.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15008" PostTypeId="1" AcceptedAnswerId="15074" CreationDate="2015-05-23T08:56:39.167" Score="4" ViewCount="3452" Body="&lt;p&gt;For smaller aircraft like Cessnas, the demonstrated crosswind component is something like 12 knots but they can land up to 20 to 25 knots. For bigger jets, such as the Boeing 737 and 777, what is the maximum crosswind component?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="65" LastEditDate="2015-05-26T14:23:50.453" LastActivityDate="2015-05-26T14:25:44.627" Title="What is the maximum crosswind component for large airliners?" Tags="&lt;aircraft-performance&gt;&lt;crosswind&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15009" PostTypeId="2" ParentId="14899" CreationDate="2015-05-23T09:18:01.187" Score="1" Body="&lt;p&gt;Static electricity is accumulation of charges over surface. During flight air frame of aircraft is exposed to the air and collision takes place between air molecules and air-frame which lead to development of electric charges over the air-frame. In my opinion water molecules on air-frame are also cause of static charge as water is slightly polar molecule it has slight negative charge on oxygen and slight positive charge on hydrogen.&#xA;Signals used in communication are electromagnetic in nature, i.e. they have electric as well as magnetic component. During interception of these communication signals with aircraft, static charges on air-frame interferes with the electric component of communication signal, hence cracking sound is there.&#xA;During lightening and thunderstorm lots of frequencies are produced sometimes these frequencies also interferes with the radio communication.&lt;/p&gt;&#xA;" OwnerUserId="8604" LastActivityDate="2015-05-23T09:18:01.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15010" PostTypeId="2" ParentId="15005" CreationDate="2015-05-23T09:33:51.927" Score="1" Body="&lt;p&gt;How is the gyroscope connected to the compass? In small aircrafts, they don't. The gyroscope itself has no idea which way is North. There is a knob next to the Direction Indicator which rotates the display. You turn it to synchronize the instrument with your magnetic compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you fly, the gyroscope will drift, so you have to synchronize it once in a while. The magnetic compass is not accurate if the aircraft is turning. Therefore, you should only synchronize when flying straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The direction gyro is accurate during turns, but will slowly drift as time goes by. Use this during maneuvers, which lasts a short period of time.&lt;/li&gt;&#xA;&lt;li&gt;The magnetic compass is inaccurate during turns, but will not drift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VFply.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this picture, the left knob rotates the instrument. The right knob sets the heading bug.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In a modern airliner, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_measurement_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight computer&lt;/a&gt; integrates electronic gyroscopes (gyroscopes on small aircrafts are often mechanic), electronic accelerometers, magnetic compass and GPS position data to determine the plane's heading, position and orientation. The synchronization is done using a set of (very complicated) math.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-23T09:33:51.927" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15011" PostTypeId="1" AcceptedAnswerId="15013" CreationDate="2015-05-23T10:01:55.557" Score="37" ViewCount="10324" Body="&lt;p&gt;I have never sat on the emergency seats near the wings, with the emergency exit. I have seen cabin crew instruct the passengers seated near the door on how to operate the door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question, what prevents a 'rogue' passenger from opening them mid-flight?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1467" LastEditDate="2015-05-23T10:31:45.770" LastActivityDate="2015-05-26T11:32:45.233" Title="What prevents a passenger from opening the emergency door on his own will, mid-flight?" Tags="&lt;emergency&gt;&lt;cabin-design&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15012" PostTypeId="2" ParentId="15011" CreationDate="2015-05-23T11:19:08.427" Score="8" Body="&lt;p&gt;The pressure differential will stop you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight the airplane is pressurized to keep you conscious at high altitude. The doors &lt;a href=&quot;http://en.wikipedia.org/wiki/Plug_door&quot;&gt;plug doors&lt;/a&gt; with flanges and must be pulled inwards to open them; those flanges make them impossible to move even after you release the latches.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="3504" LastEditDate="2015-05-23T14:16:26.087" LastActivityDate="2015-05-23T14:16:26.087" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15013" PostTypeId="2" ParentId="15011" CreationDate="2015-05-23T11:27:13.543" Score="58" Body="&lt;p&gt;At cruising altitude there is between 4 and 8 tons of pressure acting on the inside of the door. There aren't too many passengers capable of exerting that much force on the handle (and even fewer handles that won't just snap off). Latch type doors have interlocks or over-center latches that prevent operation with a pressurized cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's theoretically possible to open the over-wing exits at approach altitudes when there is no pressure differential. Other than being windy/noisy it would not affect the flight in any way. Cabin doors usually open forward, good luck pushing them open against the airflow. If the person who pulled the window plug wants out, it's their (and only their) funeral. I've sat in the open doors of light aircraft in flight hundreds of times, legs in the breeze, no seatbelt, while the plane makes fairly steep turns toward the open door side. It's not a problem. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="3504" LastEditDate="2015-05-23T14:16:47.230" LastActivityDate="2015-05-23T14:16:47.230" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15015" PostTypeId="1" AcceptedAnswerId="15043" CreationDate="2015-05-23T11:40:24.360" Score="14" ViewCount="3642" Body="&lt;p&gt;During a flight yesterday, the approach frequency for a local Class C was unusually busy. I was heading back to an underlying Class D and the frequency finally quieted down enough for me to poke in a call of &lt;code&gt;Huntsville Approach, Cessna 123AB, VFR with request&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC responded with &lt;code&gt;&amp;lt;identifier&amp;gt;, remain VFR&lt;/code&gt;. I am not positive whether he gave the full callsign or just &lt;code&gt;Tree Alpha Bravo&lt;/code&gt; — either way, definitely not &lt;code&gt;Aircraft calling&lt;/code&gt;. He did &lt;strong&gt;not&lt;/strong&gt; instruct me to &lt;a href=&quot;https://aviation.stackexchange.com/q/1314/2143&quot;&gt;remain clear&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that radar advisories are workload permitting for VFR traffic, and clearly ATC had all the workload they could handle. Does that reply establish two-way radio communication and thus permit entry into their Class C airspace, just without flight following? What if the reply had been &lt;code&gt;Tree Alpha Bravo, remain VFR&lt;/code&gt;? Assuming it does establish two-way communication, is it good Aeronautical Decision Making to fly into known busy airspace without advisories?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rather than requesting confirmation on a busy frequency, I descended below the shelf feeling like a scud runner. Approach and landing at the Class D were otherwise uneventful.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-10-22T08:14:11.463" Title="“&lt;Callsign&gt;, remain VFR” — may I enter Class C airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;&lt;phraseology&gt;&lt;class-c-airspace&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15016" PostTypeId="2" ParentId="15008" CreationDate="2015-05-23T12:01:06.833" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.planeandpilotmag.com/pilot-talk/ntsb-debriefer/the-crosswind-component.html#.VWBqSoeydLw&quot; rel=&quot;nofollow&quot;&gt;From this site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During the type certification process, the FAA requires the manufacturer to demonstrate that its airplane can be controlled in 90° crosswinds up to 20% of V&lt;sub&gt;S&lt;sub&gt;0&lt;/sub&gt;&lt;/sub&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="65" LastEditDate="2015-05-26T14:25:44.627" LastActivityDate="2015-05-26T14:25:44.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15017" PostTypeId="2" ParentId="15015" CreationDate="2015-05-23T12:23:32.410" Score="5" Body="&lt;p&gt;No clearance is required for VFR Flight in Class C airspace. It is however required to establish two way radio communications (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/A707D74273DFEF968625775800670FD9?OpenDocument&amp;amp;Highlight=91.130&quot; rel=&quot;nofollow&quot;&gt;FAR 91.130&lt;/a&gt;). The most common interpretation I've come across is that as long as ATC have responded with your callsign, you have established two way radio communications, and are therefore free to enter, unless instructed to remain clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll leave the discussion about ADM to others, but being unsure of what the ATC response meant, you took the conservative route, based on the information in your post. However, even if ATC is busy, it is very seldom too much to ask for clarification.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-23T14:03:39.953" LastActivityDate="2015-05-23T14:03:39.953" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15018" PostTypeId="1" AcceptedAnswerId="15019" CreationDate="2015-05-23T12:24:03.533" Score="11" ViewCount="2042" Body="&lt;p&gt;Short-field takeoff procedure for a Cessna 172R is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Wing Flaps – 10°.&lt;/li&gt;&#xA;  &lt;li&gt;Brakes – APPLY.&lt;/li&gt;&#xA;  &lt;li&gt;Throttle – FULL OPEN.&lt;/li&gt;&#xA;  &lt;li&gt;Mixture – RICH …&lt;/li&gt;&#xA;  &lt;li&gt;Brakes – RELEASE.&lt;/li&gt;&#xA;  &lt;li&gt;Elevator Control – SLIGHTLY TAIL LOW.&lt;/li&gt;&#xA;  &lt;li&gt;Climb Speed – 56 KIAS (until all obstacles are cleared then $V_y$).&lt;/li&gt;&#xA;  &lt;li&gt;Wing Flaps – RETRACT slowly after reaching 60 KIAS.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, best angle-of-climb or $V_x$ at is 62-67 KIAS depending on elevation. Why is the first stage of the climb slower than $V_x$, and if the slower speed gives better performance, then why isn’t that the published figure?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="7670" LastEditDate="2015-05-23T18:41:49.913" LastActivityDate="2015-05-24T01:07:37.580" Title="Why is the initial short-field climb below Vₓ in a Cessna 172?" Tags="&lt;aircraft-performance&gt;&lt;airspeed&gt;&lt;cessna-172&gt;&lt;v-speeds&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15019" PostTypeId="2" ParentId="15018" CreationDate="2015-05-23T13:00:59.090" Score="14" Body="&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_X$&lt;/span&gt; published in the manual is &lt;span class=&quot;math-container&quot;&gt;$V_X$&lt;/span&gt; for flaps up. &lt;span class=&quot;math-container&quot;&gt;$V_{X_{F10}}$&lt;/span&gt; will be slower than &lt;span class=&quot;math-container&quot;&gt;$V_{X_{UP}}$&lt;/span&gt;. Most likely, the speed in the procedure is, or is very close to &lt;span class=&quot;math-container&quot;&gt;$V_{X_{F10}}$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_X$&lt;/span&gt; (speed for angle of best climb) occurs where the excess thrust (&lt;span class=&quot;math-container&quot;&gt;$T$&lt;/span&gt; - &lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt;) is the highest. Refer to the graph below:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o8Fz0.png&quot; alt=&quot;Graph illustrating relationship between thrust, drag and Vx&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt; is Induced drag (&lt;span class=&quot;math-container&quot;&gt;$D_I$&lt;/span&gt;, varies with &lt;span class=&quot;math-container&quot;&gt;$\frac{1}{v^2}$&lt;/span&gt;) + Parasite drag (&lt;span class=&quot;math-container&quot;&gt;$D_P$&lt;/span&gt;, varies with &lt;span class=&quot;math-container&quot;&gt;$v^2$&lt;/span&gt;). By extending the flaps, you are increasing only &lt;span class=&quot;math-container&quot;&gt;$D_P$&lt;/span&gt; and the graph describing &lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt; (&lt;span class=&quot;math-container&quot;&gt;$D_{tot}$&lt;/span&gt; in the graph) moves upwards to the left. This means that the point for &lt;span class=&quot;math-container&quot;&gt;$V_{MD}$&lt;/span&gt; moves to the left. Since &lt;span class=&quot;math-container&quot;&gt;$V_X$&lt;/span&gt; is found at max &lt;span class=&quot;math-container&quot;&gt;$T - D$&lt;/span&gt; it varies with thrust too (which will vary differently, depending on the type of propulsion system), and is not automatically found at &lt;span class=&quot;math-container&quot;&gt;$V_{MD}$&lt;/span&gt;, but the two speeds generally move together in the same direction.&lt;/p&gt;&#xA;&lt;p&gt;There's also another, albeit marignal, effect (that i did not put in the graph) to take into consideration for the first 10-20 ft, and that's the ground effect. In ground effect, the aircrafts &lt;span class=&quot;math-container&quot;&gt;$D_I$&lt;/span&gt; will be lower, further moving the &lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt; graph to the left, and downwards, resulting in a lower &lt;span class=&quot;math-container&quot;&gt;$V_{MD}$&lt;/span&gt;, and therefore generally also lower &lt;span class=&quot;math-container&quot;&gt;$V_X$&lt;/span&gt;&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-24T01:07:37.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15021" PostTypeId="2" ParentId="15018" CreationDate="2015-05-23T13:27:12.880" Score="15" Body="&lt;p&gt;The published Vx is in the clean condition (no flaps): 62. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the flaps down, for a short-field takeoff, Vx is 56.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the same reason why the stall speed (bottom of the white arc) is lower with flaps than without (bottom of the green arc)&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-05-23T14:07:50.860" LastActivityDate="2015-05-23T14:07:50.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15022" PostTypeId="2" ParentId="15015" CreationDate="2015-05-23T13:48:38.580" Score="8" Body="&lt;p&gt;You have to differentiate between a &lt;strong&gt;clearance&lt;/strong&gt; which has a specific regulatory definition that is covered by numerous FARs, and the regulation which requires you to establish 2-way communication before operating in Class C or Class D.  If you hear your numbers, you have established 2-way communication, and that's it. Its not a &lt;strong&gt;clearance&lt;/strong&gt;, as defined by the FARs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Remain VFR&quot; is completely different instruction not related to permission to operate inside the Class C. It is usually given when the controller thinks you might be calling him up to request an IFR or SVFR clearance and he is telling you, in advance, that he can't do it right now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also unfortunate that &quot;remain clear&quot; and &quot;clearance/cleared&quot; both use the same word. But they mean completely different things. &quot;remain clear&quot; has nothing to do with a clearance, but tells you to remain outside the controller's airspace. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-05-23T13:48:38.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15023" PostTypeId="1" CreationDate="2015-05-23T15:36:38.683" Score="4" ViewCount="5754" Body="&lt;p&gt;I've got a question which is nearly answered by the following thread however not fully to my satisfaction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;Why do jet engines get better fuel efficiency at high altitudes?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question ultimately comes down to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do jet airplanes fly around tropopause and not higher ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the following I will relate what I believe to know and try to explain the reasoning in my mind. Please correct me in all cases where my reasoning is not entirely correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is what I get. &#xA;-Fuel efficiency becomes better with altitude &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is because even though air gets less dense in altitude (amount of oxygen per volume decreases) the ram effect compensates so that the same amount of air enters the compressor. So in comparison with low altitude,  in high altitude the same amount of air is entering the compressor so the same amount of air (number of oxygen particles) enters the combustion chamber. If the same amount of air enters the combustion chamber the same amount of fuel will be used to combust. so the same pressure and temperature is created inside the combustion chamber. &#xA;What we need for higher propulsion of the gas is the highest possible pressure difference in comparison to the ambient pressure. Higher pressure in the combustion chamber is limited by the maximum temperature the turbine blades are able to resist, so the only way to get more propulsion is a lower ambient pressure wich is the case in higher altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of that, thermal efficiency increases with lower temperatures. meaning more of all the energy inside the fuel is transferred into heat and pressure  when combusted. Only this is no more than approximately 5% in higher altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These two lead to my conclusion that in altitude you will need high speed (to create ram) this will make your engine give more propulsion/thrust for the same amount of fuel burned when flying at the same speed at lower altitude. So you are able to reduce fuel burned to create the same thrust in high altitude and thus increasing fuel efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I also know is that airplanes try to fly around the tropopause. Does it have anything to do with the characteristics of the tropopause ? &#xA;because  why don't they fly higher ? is this because temperature doesn't decrease anymore ? (this is the original story I recall from my classes a few years ago but I can't find the reasoning behind it any more) I find it now hard to believe since thermal efficiency is almost negligible. &#xA;Perhaps this is because the structure of the airplane is not able to withstand the pressure difference due to the fact the cabin pressure needs to remain below 10.000 feet ? In this it would still be true that an airplane flying higher and higher than the tropopause would get more and more fuel efficient. But also this I find hard to believe because with newer and modern composites an aeroplane should be able to withstand higher pressure differentials without adding weight and so be able to increase fuel efficiency by going higher. Cheaper and easier than developing more efficient engines I believe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So where am I wrong ?&lt;/p&gt;&#xA;" OwnerUserId="8608" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-05-23T15:41:15.923" Title="Why do (jet) airplanes fly at tropopause (and not higher)" Tags="&lt;fuel&gt;&lt;altitude&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-05-23T17:55:51.877" ContentLicense="CC BY-SA 3.0" />
  <row Id="15025" PostTypeId="1" CreationDate="2015-05-23T20:57:01.530" Score="0" ViewCount="85" Body="&lt;p&gt;A recurring theme I come across is how, in an emergency, it is safer for a passenger craft (such as an Airbus) to try to land on the ground rather than at sea. My understanding is that the main reason for this is that at the high speed at which the plane would be travelling, landing in the sea would be like hitting concrete and basically break the plane up and kill most of those on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if speed is the issue then why cannot a passenger craft just have a large parachute at the back that is deployed when the plane is say thirty to fifty feet or so above the sea surface so that the speed is drastically reduced (at a carefully pre-calculated rate that is safe for all on board, who would in any case be fully prepared for the landing), at which point the plane would essentially just guide gently into the sea at a speed maybe equivalent to that of a fast speedboat?  To be clear I am talking about a parachute that is just intended to add drag and slow the plane down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would this work in practice, and if so why don't planes have such a parachute as standard?  &lt;/p&gt;&#xA;" OwnerUserId="8072" LastActivityDate="2015-05-23T20:57:01.530" Title="Crash-landing in the sea" Tags="&lt;landing&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-05-24T00:15:53.250" ContentLicense="CC BY-SA 3.0" />
  <row Id="15026" PostTypeId="2" ParentId="15011" CreationDate="2015-05-23T21:19:52.050" Score="13" Body="&lt;p&gt;At $10,680 m$ cruising altitude air pressure is $23.8 kPa$ / $3.45psi$ / $23,800 N/m²$; compared to $101kPa$ / $14.7psi$ / $101,000 N/m^2$ at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now a 747 for example has a pressurization altitude of $2,440m$ which equates to an internal pressure of $75kPa$ / $10.9psi$ and a force of $75,000 N/m^2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the internal pressure of $75,000 N/m^2 - 23,800 N/m^2 = 51,200 N/m^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Door dimensions are $1.93m (H) \times 1.07m (W) = 2.07m^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or in feet &amp;amp; inches: $6'4&quot; (H) \times 3'6&quot; (W) = 22.17 sqft$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So $51,200 N/m^2 \times 2.0651m^2 = 105,733.12 N$  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Which equates to roughly 11.88 Metric Tonnes of force&lt;/strong&gt; on the inside of the door! The door being larger than outside portal of the door. It is forced into the frame with considerable pressure.  It would be impossible for a human to operate the door under that force.&lt;/p&gt;&#xA;" OwnerUserId="8375" LastEditorUserId="-1" LastEditDate="2015-05-26T11:32:45.233" LastActivityDate="2015-05-26T11:32:45.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15027" PostTypeId="2" ParentId="13150" CreationDate="2015-05-23T21:45:56.997" Score="2" Body="&lt;p&gt;No matter high /low capacity, airline can generate income if the plane is on the sky with sufficient passengers. That means airlines will utilise the aircrafts by maximising their operating hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between long-haul flight(s) operated by large aircrafts, there may be some &quot;gap&quot; times, airline will operate some short-haul flight by the large aircarfts to fully utilise them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using China Southern as example, two of their a380s(&lt;a href=&quot;http://www.flightradar24.com/data/airplanes/B-6136&quot; rel=&quot;nofollow&quot;&gt;B-6136&lt;/a&gt; &amp;amp; &lt;a href=&quot;http://www.flightradar24.com/data/airplanes/B-6137&quot; rel=&quot;nofollow&quot;&gt;B-6137&lt;/a&gt;) are used for short route CAN-BEK (~1100 miles) and at night they will be used for CAN-LAX (~7200 miles) and come back to Baiyun airport in the early morning of two days after (China time zone). However most of the other airlines has more complex schedules, the aircrafts used for EK&lt;a href=&quot;http://www.flightradar24.com/data/flights/ek857&quot; rel=&quot;nofollow&quot;&gt;857&lt;/a&gt;/&lt;a href=&quot;http://www.flightradar24.com/data/flights/ek858&quot; rel=&quot;nofollow&quot;&gt;858&lt;/a&gt;(DXB-KWI), the A380 shortest route(~550 miles), are used for many meduim/long-haul destinations, including MUM, JFK, HKG, LHR, SYD, BKK, FCO, BNE......&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS:Jon Story answer claimed that &quot;long haul routes tend to have less frequent service with larger, higher capacity aircraft&quot;;however some airlines actually uses smaller aircrafts with more frequent services. Cathay have 5+ daily HKG-LHR routes (~6000miles) with b77W, exclude the night time there is approximately 3-4hrs average for each departures. Using &quot;smaller&quot; B777 (instead of A380) means more flexible choices for customers and the aircrafts can also be used for lower capacity long-haul routes.  &lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-05-23T22:47:02.013" LastActivityDate="2015-05-23T22:47:02.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15028" PostTypeId="2" ParentId="15011" CreationDate="2015-05-24T00:44:31.060" Score="19" Body="&lt;p&gt;In addition to the pressure differential, some aircraft also have mechanical locks. Here's the logic diagram for a 737 NG. This will be similar to all of Boeing's exit doors that are hinged at the top.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X30tv.png&quot; alt=&quot;Door lock logic diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These conditions cause the emergency exit doors to lock:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Three or more of the entry/service doors are closed, and&lt;/li&gt;&#xA;&lt;li&gt;Either left or right engine is running, and&lt;/li&gt;&#xA;&lt;li&gt;Air ground logic is in the AIR MODE, or&lt;/li&gt;&#xA;&lt;li&gt;The left and right thrust levers are advanced more than 53 degrees&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-05-24T17:09:23.060" LastActivityDate="2015-05-24T17:09:23.060" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15029" PostTypeId="2" ParentId="11818" CreationDate="2015-05-24T02:25:54.620" Score="0" Body="&lt;p&gt;The cue I was taught related to the visual effect of the runway &quot;widening&quot; as you arrived at the proper flare point. Mind you, this effect will occur at different altitudes depending on the runway width. I trained at a field where the main runway had a paved width of only 25ft. Visiting a larger airport with a runway say 200ft wide required a bit of an adjustment to avoid flaring too high. Nevertheless, it is possible to develop a &quot;feel&quot; (visual, not seat-of-the-pants) for your height over the runway based on the way the edges of the runway (or lines of runway lights) appear to widen out.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-24T02:25:54.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15030" PostTypeId="2" ParentId="3423" CreationDate="2015-05-24T02:39:00.997" Score="2" Body="&lt;p&gt;One can imagine a relatively simple and robust linkage between the lever and flaps on a low wing e.g. Piper Cherokee. Maybe not so straightforward for a high wing like a C-172, where there is likely already a complex cable routing for the ailerons.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-24T02:39:00.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15031" PostTypeId="2" ParentId="8917" CreationDate="2015-05-24T03:24:40.720" Score="2" Body="&lt;p&gt;An aircraft that has poor glide performance (descends steeply when not under engine power) will be very fuel inefficient and therefore uneconomic and unprofitable to fly commercially. The mass of the plane descending at some uniform rate represents a dissipation of potential energy. If that energy goes into sustaining forward speed, then the plane is in a glide. To keep the plane in level flight at the same forward speed, the engines would have to supply energy in the form of thrust at that same rate as it would be dissipated in a glide. The less work the engines have to do to maintain that speed, the less fuel they use, and the less height the plane would lose in an unpowered glide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you can be pretty sure that your economy fare ticket will buy you a seat on a plane that can glide pretty well should the engines ever quit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total engine failures are pretty rare events. The most notable events in recent years where all engines failed have all ended with 100% survival (although the aircraft didn't always fare too well). In a couple of cases, the aircraft glided to a runway landing and the landing gear got a bit bent up (hard landings because the pilot has only one try at the approach and may not have working flaps, won't have reverse thrust to aid braking). In another case, the plane landed safely on a grass levee without damage. In one case, the plane landed on water - total write-off, but everyone made it to safety. In one other case, all engines quit due to volcanic ash ingestion, but were later restarted  in flight, allowing the crew to make a more-or-less normal landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft nose-dive and crash into the Earth for one of only two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Someone at the controls points it at the ground&lt;/li&gt;&#xA;&lt;li&gt;Some vital part of the aircraft structure or control system breaks&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Again, these are both &lt;em&gt;extremely&lt;/em&gt; rare occurrences. Far more likely someone driving a car will fail to pay proper attention to the task and hit you while you are on your way to the airport.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="3218" LastEditDate="2016-06-26T21:32:30.360" LastActivityDate="2016-06-26T21:32:30.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15033" PostTypeId="2" ParentId="14976" CreationDate="2015-05-24T04:58:19.857" Score="3" Body="&lt;p&gt;The B-52 Stratofortress is a military jet, and specifically a US military jet, which if flown over USSR was very much in risk of being harmed. Thus, it was an intelligent decision to follow a longer route, rather than being a victim of ongoing cold war, following the longer route could have also helped the crew in achieving the longest flight record. Secondly, the B-52 did not have a very good &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress#Notable_accidents&quot; rel=&quot;nofollow&quot;&gt;history&lt;/a&gt; even before 1962, thus taking precautions was a necessity for the crew, and they did this by choosing to fly over more helpful nations.  Also, aviation was not developed very much in Asia back in 1962 with very few strips of a large distance, to be used in case of emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, you may refer &lt;a href=&quot;http://www.thisdayinaviation.com/tag/clyde-p-evely/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://www.minotdailynews.com/page/content.detail/id/519514.html?nav=5576&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;!&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-05-24T09:24:32.373" LastActivityDate="2015-05-24T09:24:32.373" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15034" PostTypeId="2" ParentId="14841" CreationDate="2015-05-24T07:51:53.697" Score="0" Body="&lt;p&gt;The Harrier's wings have large anhedral, the wingtips are close to the ground. Without the outriggers there is a risk that payload carried back to base on the outer pylons gets damaged if the pilot sets down the aircraft with a roll angle or a roll rate causing a roll angle to build up.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-05-24T07:51:53.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15035" PostTypeId="1" AcceptedAnswerId="15036" CreationDate="2015-05-24T09:28:47.883" Score="8" ViewCount="1969" Body="&lt;p&gt;I just heard that  1930s-40s planes such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_B-17_Flying_Fortress&quot;&gt;B-17&lt;/a&gt; were not pressurized. Is this true? If yes, then how did the military men survive at heights of 30k ft?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-05-24T10:10:01.790" Title="Were early military planes not pressurized?" Tags="&lt;military&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15036" PostTypeId="2" ParentId="15035" CreationDate="2015-05-24T09:37:15.687" Score="11" Body="&lt;p&gt;There were a few problems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pressurization (while not impossible) was difficult requiring extra effort. It also increased weight and complexity.&lt;/li&gt;&#xA;&lt;li&gt;Pressurization was still a relatively new technology at the time. For reference, the first pressurized commercial aircraft, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_307_Stratoliner&quot; rel=&quot;noreferrer&quot;&gt;Boeing 307 Stratoliner&lt;/a&gt;, made its first flight later the same year (1938) as the B17. Note that it was developed from the B17.&lt;/li&gt;&#xA;&lt;li&gt;There was an incredible amount of openings on early planes for gun turrets, bomb bays, etc. Sealing these off airtight would have been a impractical nightmare. You would traverse the bomb bay move to the back and front of the plane.&lt;/li&gt;&#xA;&lt;li&gt;It's also better from a reliability standpoint- it's pretty easy to damage and make a hole in the fuselage, but everybody having their own oxygen masks removes that single point of failure. &lt;/li&gt;&#xA;&lt;li&gt;While perhaps (I imagine) not incredibly comfortable for long duration missions oxygen masks worked fine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;30,000ft corresponds to around 9,200m, although that altitude is a ceiling defined by Boeing. With full load, they never achieved those altitude and hung around a lot lower. While I can't verify it, these &lt;a href=&quot;http://www.armyairforces.com/Typical-altitude-for-B17-missions-m72178.aspx&quot; rel=&quot;noreferrer&quot;&gt;forum posters&lt;/a&gt; appears to suggest that 19,000ft-28000ft with bombs was more common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To do the math, the partial pressure of oxygen at sea level is around 0.21 bar. If you're being fed 100% oxygen through your mask, this is the same pressure as at 11,000m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/woylL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;em&gt;Photo by Margaret Bourke-White, Sept. 1942, from the LIFE Archives.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-24T10:10:01.790" LastActivityDate="2015-05-24T10:10:01.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15037" PostTypeId="1" AcceptedAnswerId="15041" CreationDate="2015-05-24T09:38:05.097" Score="9" ViewCount="2971" Body="&lt;p&gt;For example, the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CCAQFjAA&amp;amp;url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBoeing_747&amp;amp;ei=l5thVau_OZWTuASo9oG4DA&amp;amp;usg=AFQjCNHLtbS1KjcZbeUvJkPXTYsib18W7w&amp;amp;bvm=bv.93990622,d.c2E&quot;&gt;Boeing 747&lt;/a&gt; has four engines, whereas the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CCAQFjAA&amp;amp;url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBoeing_737&amp;amp;ei=wJthVb2iEIWzuATtzIDACQ&amp;amp;usg=AFQjCNE2ktoKBrKoWurOPdxJPBrMfA-0GA&quot;&gt;Boeing 737&lt;/a&gt; has 2. Does this means that the Boeing 747 would be safer if one of the engines fail?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="790" LastEditDate="2015-05-25T09:48:05.750" LastActivityDate="2015-07-23T17:17:21.323" Title="Does adding more engines to commercial aircraft increase safety?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;" AnswerCount="5" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15038" PostTypeId="1" AcceptedAnswerId="15040" CreationDate="2015-05-24T13:26:47.750" Score="11" ViewCount="19529" Body="&lt;p&gt;How to recover from a spin in a Cessna 172 ? What are the different maneuvers that a pilot would have to use to to do so?&lt;/p&gt;&#xA;" OwnerUserId="8533" LastEditorUserId="64" LastEditDate="2016-02-02T03:27:23.270" LastActivityDate="2018-10-10T19:51:49.470" Title="How to Recover from a Spin in Cessna 172?" Tags="&lt;student-pilot&gt;&lt;cessna-172&gt;&lt;spins&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15039" PostTypeId="2" ParentId="1189" CreationDate="2015-05-24T13:41:41.847" Score="0" Body="&lt;p&gt;If you are doing touch-and-go practice, you probably have to raise the flaps to a take-off setting while still rolling down the runway because most planes don't climb well on full flaps. If you get trained into doing that, maybe it becomes habit (for better or worse) to raise the flaps during roll-out even when your intent is a full stop.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-24T13:41:41.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15040" PostTypeId="2" ParentId="15038" CreationDate="2015-05-24T14:57:54.130" Score="15" Body="&lt;p&gt;The memory aid is PARE:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;POWER&lt;/strong&gt; to idle&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;AILERONS&lt;/strong&gt; neutral&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;RUDDER&lt;/strong&gt; on the floor opposite the direction of spin&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;ELEVATOR&lt;/strong&gt; nose-down to break the stall&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You will want to read the full explanation in the Pilots Operating Handbook or POH for an understanding of the steps and why you need to take them. Commit the sequence above to memory and better yet get spin training from a qualified instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The POH for the 172N model reads (caps and &lt;strong&gt;boldface&lt;/strong&gt; in original):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Should an inadvertent spin occur, the following recovery procedure should be used:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;RETARD THROTTLE TO IDLE POSITION.&lt;/li&gt;&#xA;  &lt;li&gt;PLACE AILERONS IN NEUTRAL POSITION.&lt;/li&gt;&#xA;  &lt;li&gt;APPLY AND &lt;strong&gt;HOLD&lt;/strong&gt; FULL RUDDER OPPOSITE TO THE DIRECTION OF ROTATION.&lt;/li&gt;&#xA;  &lt;li&gt;JUST &lt;strong&gt;AFTER&lt;/strong&gt; THE RUDDER REACHES THE STOP, MOVE THE CONTROL WHEEL &lt;strong&gt;BRISKLY&lt;/strong&gt; FORWARD FAR ENOUGH TO BREAK THE STALL. Full down elevator may be required at aft center of gravity loadings to assure optimum recoveries.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;HOLD&lt;/strong&gt; THESE CONTROL INPUTS UNTIL ROTATION STOPS. Premature relaxation of the control inputs may extend the recovery.&lt;/li&gt;&#xA;  &lt;li&gt;AS ROTATION STOPS, NEUTRALIZE RUDDER, AND MAKE A SMOOTH RECOVERY FROM THE RESULTING DIVE.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;NOTE&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;If disorientation precludes a visual determination of the direction of rotation, the symbolic airplane in the turn coordinator may be referred to for this information.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Other Spin Recovery Methods&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The methods below may or may not recover from all spins. Seek out a qualified instructor for spin training — or, better yet, &lt;em&gt;avoid spins altogether!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Finagin&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Finagin advocates a four-step recovery technique for unintentional spins and departures from controlled flight that pilots can put to use without hesitation — and without fear of making the situation worse — even when they’re confused or disoriented by the unusual attitudes and strange sensations that can accompany spins.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Rip the power to idle. &lt;/li&gt;&#xA;  &lt;li&gt;Forcefully neutralize the stick and rudder pedals. &lt;/li&gt;&#xA;  &lt;li&gt;Look at the airspeed indicator, and once it shows 100 knots or more (roughly 1.4 times the airplane’s stall speed) … &lt;/li&gt;&#xA;  &lt;li&gt;Pull out of the dive.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Source:&lt;/strong&gt; &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/2010/june/03/spin-myths&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Beggs-Mueller&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Power – Off.&lt;/li&gt;&#xA;  &lt;li&gt;Remove your hand from the stick.&lt;/li&gt;&#xA;  &lt;li&gt;Apply full opposite rudder until rotation stops.&lt;/li&gt;&#xA;  &lt;li&gt;Neutralize rudder and recover to level flight.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Source:&lt;/strong&gt; &lt;a href=&quot;https://www.eaa.org/en/eaa-shop/iac_merchandise/7251711200000__Spins_in_the_Pitts_Special&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Spins in the Pitts Special&lt;/em&gt;&lt;/a&gt; by Gene Beggs&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Hands In Your Lap&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Some advocate the “hands in your lap” method of pulling power, taking your hands (and feet) off the flight controls, and waiting for the airplane to fly itself out of the spin. This may work for certain airframes but not all. Catherine Cavagnaro of &lt;a href=&quot;http://www.aceaerobaticschool.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ace Aerobatic School&lt;/a&gt; says she likes to perform spin training in a Cessna&amp;nbsp;152 because that airplane will not self-recover from a spin.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2018-10-10T10:51:26.990" LastActivityDate="2018-10-10T10:51:26.990" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="15041" PostTypeId="2" ParentId="15037" CreationDate="2015-05-24T14:59:22.353" Score="15" Body="&lt;p&gt;&lt;strong&gt;In the modern day and age, it is very difficult to put a numerical value to this type of question, simply because the chance of something happening is so incredibly remote. This is not a clear-cut equation and is dependant on several factors.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A few thoughts:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The impact of loosing one engine will be less significant on a four-engined aircraft than a two-engined aircraft. You only loose 25% of thrust as compared to 50%. However, two engined jets are built with greater safety margin and are able to handle an engine failure at any phase in the flight. Four engined jets are certified to be able to fly on two engines on one side of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, you are twice as likely to suffer an engine failure with four engines, since you have twice as many engines. While the lost thrust would be less significant, very rarely damage can propagate to cause damage to other parts (See &lt;a href=&quot;http://en.wikipedia.org/wiki/Qantas_Flight_32&quot;&gt;QF32&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/El_Al_Flight_1862&quot;&gt;ELY1862&lt;/a&gt;). In general, it is easier, cheaper and faster to maintain two engines than four. Should a complete engine swap be necessary for instance, you only need to do it twice instead of four times. Every extra step is an step where something could theoretically could go wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.sae.org/aeromag/features/aircraftengines/02.htm&quot;&gt;GE90&lt;/a&gt; (Boeing 777) is certified to handle 'large' birds (4kg) as compared to the &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/EASA-TCDS-E.003_CFM_International_S.A._--_CFM56--5Band5C_series_engines-03-17122012.pdf&quot;&gt;CFM56&lt;/a&gt; (Airbus A340) only being able to handle 'medium' birds. Hence, the Boeing 777 engines are likely to be a bit more robust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a human perspective, pilot workload will be lower with two engines rather than four. Should something happen in a time-critical emergency, there will be more systems you need to keep an overview of. See &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot;&gt;CAL006&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, not every engine-related incident is spared simply cause you have four engines. &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_9&quot;&gt;BA Flight 9&lt;/a&gt; lost all four engines due to volcanic ash. On &lt;a href=&quot;http://en.wikipedia.org/wiki/British_Airways_Flight_38&quot;&gt;BA Flight 38&lt;/a&gt;, the engines failed in unison due to ice in the heat exchanger on the engines that were operating in identical conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Despite ETOPS being around for several decades and applying to thousands of aircraft I have not heard about a single accident involving commercial jets operating in that domain.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="524" LastEditDate="2015-05-24T19:35:39.470" LastActivityDate="2015-05-24T19:35:39.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15042" PostTypeId="1" CreationDate="2015-05-24T15:13:04.617" Score="20" ViewCount="15818" Body="&lt;p&gt;&lt;a href=&quot;https://travel.stackexchange.com/questions/40180/why-did-the-stewardess-make-me-wait-before-disembarking&quot;&gt;This question on Travel.SE&lt;/a&gt; recounts a situation where a passenger, about to disembark from a commercial airline flight, was asked by a flight attendant to wait for other passengers to &quot;catch up&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://travel.stackexchange.com/a/48157/1362&quot;&gt;This answer&lt;/a&gt; suggests that if too many passengers were to disembark from the front, while passengers at the back remained at the back, the plane might tip backward; and that the flight attendant was acting to avoid this possibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this really a risk on modern airliners, or even regional jets or turboprops?  (The aircraft in the question at hand was a 737.)  Are flight attendants trained to redirect or hold passengers in order to avoid it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I saw &lt;a href=&quot;https://aviation.stackexchange.com/questions/1659/is-passenger-weight-distribution-important-on-a-commercial-flight?rq=1&quot;&gt;Is passenger weight distribution important on a commercial flight?&lt;/a&gt; but it is about the aerodynamic effects of passenger distribution, which are not relevant when the airplane is parked on the ground.&lt;/p&gt;&#xA;" OwnerUserId="2546" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-12-25T13:17:52.253" Title="Can passenger distribution cause a parked airliner to tip?" Tags="&lt;weight-and-balance&gt;" AnswerCount="8" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15043" PostTypeId="2" ParentId="15015" CreationDate="2015-05-24T15:39:40.613" Score="16" Body="&lt;p&gt;Yes, you were allowed to enter the class C in that case, but you weren't &lt;em&gt;cleared&lt;/em&gt; to do it because no clearance is needed to operate in class C, just communication with ATC. The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/AIM_Basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; 3-2-4 has the best explanation of this (see also the basic regulation in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1130&quot;&gt;14 CFR 91.130&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;If the controller responds to a radio call with, “(air craft callsign) standby,” radio communications have been established and the&#xA;  pilot can enter the Class C airspace.&lt;/li&gt;&#xA;  &lt;li&gt;If workload or traffic  conditions prevent immediate provision of  Class C services, the controller will inform the pilot to remain&#xA;  outside the Class C airspace until conditions permit the services to&#xA;  be provided.&lt;/li&gt;&#xA;  &lt;li&gt;It is important to understand that if the controller responds to  the initial radio call without  using the  aircraft identification,&#xA;  radio communications have not been established and the pilot may not&#xA;  enter the Class C airspace.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if the controller used your callsign then you've established radio communications and you can enter. This also applies to class D but not to class B, where you need an actual clearance to enter. (This is a classic exam question/scenario, by the way.) As @rbp suggested, the instruction to &quot;maintain VFR&quot; was probably the controller's way of letting you know up front that he was too busy to give you a pop-up IFR clearance or whatever else you might have wanted. (&lt;em&gt;Maintain&lt;/em&gt; is &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/PCG_4-03-14.pdf&quot;&gt;an official ATC term&lt;/a&gt;, &lt;em&gt;remain&lt;/em&gt; is not, although the controller may still have used it accidentally.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for flying into busy airspace, it's up to you as PIC to determine what's safe and what isn't. If you had the HSV ATIS (so you can anticipate traffic patterns), were squawking 1200, were in communication with ATC and were keeping your eyes outside the cockpit then there's not too much more you can do (you could turn on all your lights if you think you need to make yourself more visible). But, if you ever feel unsafe or uncomfortable in any flight situation then you shouldn't hesitate to take action - like staying clear of the class C for a few minutes - if you do feel it's necessary, that's simply part of gaining ADM experience.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-24T15:39:40.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15044" PostTypeId="1" AcceptedAnswerId="15056" CreationDate="2015-05-24T16:28:43.947" Score="4" ViewCount="342" Body="&lt;p&gt;How does a propeller remain attached to the engine? I know there is a gearbox and/or some other mechanism that transmit the movement but is there any security mechanism that avoids it from completely detaching from the main engine? There is a huge amount of forces acting on that tiny spot where the propeller is attached to the engine, especially on turboprops, and this is where my question comes from. &lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2015-05-24T17:31:15.770" LastActivityDate="2015-05-25T02:40:39.233" Title="What prevents a propeller from detaching completely from the engine body?" Tags="&lt;propeller&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15045" PostTypeId="1" AcceptedAnswerId="15049" CreationDate="2015-05-24T16:38:13.480" Score="6" ViewCount="436" Body="&lt;p&gt;To which point of the aircraft is the altimeter reading referred to? Is it referred to the probe position or is it offset to read as if it was at the bottom of the fuselage or the landing gear? If it was a GA aircraft I suppose it wouldn't make a difference, but on something big as a 747 or an A380, should it be set at the same level as the probe, there would be quite a difference compared to the ground (maybe 20-30 feet?). If so, how is this handled?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2016-07-14T07:58:06.800" LastActivityDate="2016-07-14T07:58:06.800" Title="To which reference point on the aircraft is the altimeter reading relative to?" Tags="&lt;altimeter&gt;&lt;calibration&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15046" PostTypeId="5" CreationDate="2015-05-24T16:38:54.630" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-05-24T16:38:54.630" LastActivityDate="2015-05-24T16:38:54.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15047" PostTypeId="4" CreationDate="2015-05-24T16:38:54.630" Score="0" Body="Adjusting an instrument to improve the accuracy of measurements." OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-05-24T18:15:45.183" LastActivityDate="2015-05-24T18:15:45.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15049" PostTypeId="2" ParentId="15045" CreationDate="2015-05-24T16:52:54.080" Score="6" Body="&lt;p&gt;The placement of a probe for a pressure  altimeter has exactly the problem you mention, but they only need to be accurate within 75 feet, so placement is not a problem. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For large aircraft, they use a &quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;nofollow&quot;&gt;radar altimeter&lt;/a&gt;&quot; which uses an electromagnetic beam to measure the distance to the ground, the same way police radars measure car speed. Radar altimeters are accurate to within a couple of feet. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="770" LastEditDate="2015-05-24T17:33:38.113" LastActivityDate="2015-05-24T17:33:38.113" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15050" PostTypeId="1" CreationDate="2015-05-24T18:01:10.817" Score="0" ViewCount="215" Body="&lt;p&gt;Whenever an airliner crashes, inevitably questions arise as to how can the planes be made safe and ultimately, how can we avoid loss of lives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though statistically, modern airliners are safest ever, but due to the nature and outcome of even a single crash, it affects people psychologically worldwide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions like parachutes for planes or even passengers are numerous on this site. For example, I posted this questions after reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/9564/why-dont-big-commercial-planes-have-full-aircraft-parachutes&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I understand, if an aircraft can be slowed down, by means of a parachute, the resultant damgage to human lives would be a lot less. This led me to wonder, &lt;strong&gt;what can be other means of slowing down an aircraft, which would crash otherwise&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-25T11:38:58.750" Title="Are there other practical means of 'slowing' down an aircraft, other than parachutes?" Tags="&lt;safety&gt;&lt;cabin-design&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-05-25T15:18:18.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="15051" PostTypeId="2" ParentId="15037" CreationDate="2015-05-24T18:03:46.177" Score="2" Body="&lt;p&gt;If an engine fails, the fraction of loss of thrust is smaller for an aircraft with four engines than for one with two. If other things happen, for example loss of rudder, yaw control is easier with three remaining engines than with one.&#xA;So in terms of %-loss of thrust and what this entails, a 4-engine plane is safer than a 2-engine plane.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorDisplayName="user7241" LastEditDate="2015-05-25T12:20:18.087" LastActivityDate="2015-05-25T12:20:18.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15052" PostTypeId="2" ParentId="15037" CreationDate="2015-05-24T20:51:03.783" Score="3" Body="&lt;p&gt;From a strictly &quot;engine cut out&quot; point of view in todays day and age you are not getting your self very much. There is a &lt;a href=&quot;http://www.flyingmag.com/what-happened-piston-twin&quot; rel=&quot;nofollow&quot;&gt;great article here&lt;/a&gt; that talks quite a bit about this point from a GA stand point. There is of course the simple fact that for some planes you need more thrust to simply fly. There has also been lots of research done on if servicing an engine frequently makes it safer or actually adds to the problem. Again from a GA (mainly piston) standpoint &lt;a href=&quot;http://blog.aopa.org/opinionleaders/2014/03/13/do-tbos-make-sense/&quot; rel=&quot;nofollow&quot;&gt;there is a case to be made.&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-24T20:51:03.783" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15053" PostTypeId="2" ParentId="15050" CreationDate="2015-05-24T21:25:57.680" Score="0" Body="&lt;p&gt;There are a few things you could do but a full frame chute would be the most effective.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed brakes and flaps (really anything that creates drag) can act to slow a plane down even in a glide (engine out) situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the realm of more unlikely things some sort of rocket style short burn booster can be deployed and discharged apposing the direction of movement &lt;a href=&quot;http://en.wikipedia.org/wiki/Apollo_Lunar_Module#Descent_stage&quot; rel=&quot;nofollow noreferrer&quot;&gt;thats how we landed on the moon&lt;/a&gt;. But these would add weight to the aircraft and could (if deployed incorrectly) put the aircraft in a worse situation. This does NOT include deploying thrust reversers &lt;a href=&quot;https://aviation.stackexchange.com/questions/9577/is-it-possible-to-use-reverse-thrust-while-airborne&quot;&gt;that can be dangerous.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Slip_%28aerodynamics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Slipping&lt;/a&gt; an aircraft (rudder opposite aileron deflection) can aid in slowing an airplane down. All student pilots in the US are required to know how to do this. Its strange the first time but quite interesting to execute.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-05-24T22:11:50.873" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15054" PostTypeId="2" ParentId="15005" CreationDate="2015-05-24T22:48:16.293" Score="2" Body="&lt;p&gt;Gyromagnetic compasses do indeed exist even in smaller aircraft, and need not be overly complex. The basic principle for an analog system is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heading is measured against a gyro rotating in the vertical plane (just like a normal heading indicator). The gyro may be in the instrument case, or electronically repeated from elsewhere in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The earth's magnetic field is sensed by a sensing unit, a &quot;Flux valve&quot; usually located in the wing, or otherwise in a good position to minimize electromagnetic interference from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gyro position and the magnetic reference are compared electronically and the resulting difference becomes an error signal. This error signal is sent to electric motors on the gyro frame, which will move to very slowly (a few degrees per minute) correct the gyro to align with the magnetic reference, combining the short term accuracy of the gyro with the long term accuracy of the earth magnetic field. To further enhance accuracy, cut-out switches cuts the error signal out when the aircraft is banking/accelerating, as this tends to give a less precise magnetic signal from the flux valve, while a gyro is unaffected by it. See the &lt;a href=&quot;https://www.bendixking.com/HWL/media/Pilot-Guides/006-08256-0004_4.pdf&quot; rel=&quot;nofollow&quot;&gt;Bendix King KCS55A&lt;/a&gt; for a real life example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On older, larger aircraft, you'll find similar installations. On modern aircraft, with inertial navigation platforms (IRS) heading is often taken from the inertial platform as true heading, with magnetic variation applied from a database to provide magnetic heading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The IRU will in that case (among other things) act as a kind of gyrocompass, finding true north by leveling and rotating 3 nowadays usually mathematically modelled gyro planes (solid state &lt;a href=&quot;http://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;nofollow&quot;&gt;Ring Laser Gyros&lt;/a&gt;, no moving parts), to align with true north, by sensing gravitation and angular movement around gyro axes from the rotation of the earth. The planes are then kept level by integrating gyro data, and filtering/fusing it with accelerometer data, movement over earth curvature, &lt;a href=&quot;http://en.wikipedia.org/wiki/Schuler_tuning&quot; rel=&quot;nofollow&quot;&gt;Schuler tuning&lt;/a&gt;, other sensor data etc.)&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-05-25T00:08:36.290" LastActivityDate="2015-05-25T00:08:36.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15055" PostTypeId="2" ParentId="15042" CreationDate="2015-05-25T01:00:18.687" Score="8" Body="&lt;p&gt;It's possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When FedEX used 727s a lot they had regular occurrences of cargo being loaded too far back while the front was empty. The airplane would sit on it's tail. Not usually damaging but having the front door quite a bit higher than usual was an issue. If no one was on board it was awkward to get it back to normal, and FedEX &lt;em&gt;really&lt;/em&gt; doesn't like delays. At my airport in the 90s you often saw a post attached to the tail while they ere loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Highly unlikely a 747 will rise up like a bucking horse, but it is possible that you can take enough weight off the nose gear of something smaller that the strut can extend. This would make the cabin door rise by about a foot, probably hit the jetway, and upset most everyone onboard. What would the passengers probably do? That's right - run downhill.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-05-25T01:00:18.687" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15056" PostTypeId="2" ParentId="15044" CreationDate="2015-05-25T02:40:39.233" Score="8" Body="&lt;p&gt;Nuts. Technically nuts and bolts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at pictures of propeller hubs (google &quot;propeller hub&quot;) you'll see that the individual prop blades are held onto the prop hub by nuts and bolts holding the hub halves together. Or for wooden props they're bolted directly onto the hub.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you then take the hub apart, you'll see that the hub is attached to the shaft using nuts and bolts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I sometimes see people asking why aircraft engineers specify very expensive nuts and bolts for certain parts of the aircraft when a cheaper part can handle an equivalent load. Your question is exactly the reason - it's better to over-engineer certain parts like the prop assembly than have the prop accidentally fly off during flight.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-05-25T02:40:39.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15057" PostTypeId="2" ParentId="170" CreationDate="2015-05-25T03:05:58.510" Score="4" Body="&lt;p&gt;Cracks in fuselage while boarding. There was flight where a passenger noticed a crack and was too shy to tell cabin crew. The fuselage peeled in flight and at least one person died.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight was &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aloha 243&lt;/a&gt;, a Boeing 737 flying from Hilo to Honolulu that diverted to Kahului, Maui after a very large portion of the top-forward fuselage ripped off due to rapid decompression resulting from metal fatigue cracks. According to the end of Section 1.1 of &lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR89-03.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the NTSB Report&lt;/a&gt; (page 5, 2nd paragraph):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After the accident, a passenger stated that as she was boarding the airplane through the jet bridge at Hilo, she observed a longitudinal fuselage crack. The crack was in the upper row of rivets along the S-10L lap joint, about halfway between the cabin door and the edge of the jet bridge hood. She made no mention of the observation to the airline ground personnel or the flight crew.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There was 1 death (a flight attendant who was sucked out of the aircraft) and 65 injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Section 1.1 of &lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR89-03.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the NTSB Report&lt;/a&gt; (page 2, last paragraph):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the decompression occurred, all the passengers were seated and the seat belt sign was illuminated. The No. 1 flight attendant reportedly was standing at seat row 5. According to passenger observations, the flight attendant was immediately swept out of the cabin through a hole in the left side of the fuselage. The No. 2 flight attendant, standing by row 15/16, was thrown to the floor and sustained minor bruises. She was subsequently able to crawl up and down the aisle to render assistance and calm the passengers. The No. 3 flight attendant, standing at row 2, was struck in the head by debris and thrown to the floor. She suffered serious injuries including a concussion and severe head lacerations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The remnants of N73711 (the aircraft operating Aloha 243):&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9DslB.png&quot; alt=&quot;Aloha 243&quot;&gt;&lt;br&gt;&#xA;Image Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Aloha_Airlines_Flight_243_fuselage.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2671" LastEditorUserId="755" LastEditDate="2015-08-18T05:33:23.153" LastActivityDate="2015-08-18T05:33:23.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15058" PostTypeId="2" ParentId="15042" CreationDate="2015-05-25T03:53:52.373" Score="7" Body="&lt;p&gt;A quick search reveals it has happened on cargo planes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hfmdh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VzSEG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually passengers are not that heavy, and there isn't really that much room for 300 people to rush to the back.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-25T03:53:52.373" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15059" PostTypeId="2" ParentId="14945" CreationDate="2015-05-25T05:05:31.910" Score="4" Body="&lt;p&gt;100 octane fuel was the best possible aviation fuel at that time,introduced in April 1940 .By December 1942, production of 100 octane gasoline had risen to 5.5 million gallons/day; by June 1943, it was approaching 10 million gallons/day; and, by VE-Day, May 7,1945, production exceeded 20 million gallons/day. Avgas was introduced near 1970s. And, then it is very difficult to find exact price for that . But, the at that time the price of car fuel and aviation fuel were not very different. So, you can estimate it to be at 10-12 cents/gallon range. One other way to estimate the cost is by using the inflation adjusters, the &lt;a href=&quot;http://www.100ll.com/&quot; rel=&quot;nofollow&quot;&gt;current price&lt;/a&gt; for 100LL is about $5.5 . So, by using this &lt;a href=&quot;http://www.thisismoney.co.uk/money/bills/article-1633409/Historic-inflation-calculator-value-money-changed-1900.html&quot; rel=&quot;nofollow&quot;&gt;calculator&lt;/a&gt;, it would have cost nearly 10 cents/gallon. (In 1940, Dollar and Pound were nearly same in value.) So, the final answer should be about 10 cents/gallon.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-05-26T04:40:11.717" LastActivityDate="2015-05-26T04:40:11.717" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15061" PostTypeId="2" ParentId="15050" CreationDate="2015-05-25T11:38:58.750" Score="1" Body="&lt;p&gt;For an aircraft to fly, it needs forward speed. If you slow down an aircraft too much, it will stall and fall out of the sky. &lt;strong&gt;&lt;em&gt;Airplanes are designed to not slow down.&lt;/em&gt;&lt;/strong&gt; It's not &quot;if a Boeing 737 is slowed down to 80 knots, more people will survive&quot;. A Boeing 737 &lt;em&gt;has&lt;/em&gt; to fly at 130 knots minimum. If you want a machine that can, it's a helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most crashes happen suddenly, e.g. &lt;a href=&quot;http://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow&quot;&gt;approaching a runway while not paying attention to airspeed&lt;/a&gt;. It's not like &quot;&lt;em&gt;Hmmm, I think it's going to crash in 3 minutes, let's arm this system to minimize injury&lt;/em&gt;&quot;. It's like, &quot;&lt;em&gt;we're stable, runway ahead, everything's good......(terrain! terrain! PULL UP!)......oh sh!t ! Max power!!!&lt;/em&gt;&quot;. If the pilot can foresee the accident, most of the time he can avoid it altogether.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you know well in advance you &lt;em&gt;ARE&lt;/em&gt; going to crash, chances are the aircraft is completely out of control, spinning around and falling. In this case I think a large enough parachute will be effective.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-25T11:38:58.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15062" PostTypeId="2" ParentId="15042" CreationDate="2015-05-25T12:45:56.913" Score="3" Body="&lt;p&gt;Most times when tipping is a risk is with smaller aircraft that have the cargo loaded before or after all the passengers in behind the passenger deck. The cargo aircraft you see above are also shifting substantial weight in a very organized fashion. You are gradually moving each container forward, while leaving the other ones behind the main gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tipping over a 737 is not a trivial task I could only find very few occurrences online. Here is why I'm not buying the tipping over argument from the OP at Travel SE: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Tipping over is dangerous for the 100+ passengers still on board. I don't think a lone flight attendant is sufficient integrity to prevent such an event from occurring. If it would be a genuine problem, there would be more measures in place.&lt;/li&gt;&#xA;&lt;li&gt;The change in weight from the first 5 rows of passengers is pretty insignificant. Ryanair for instance has a habit of even blocking them off entirely when the aircraft is not fully loaded.&lt;/li&gt;&#xA;&lt;li&gt;There are (very) few recorded instances of it happening despite thousands of 737s in operation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most aircraft are designed with bit of weight on the nosewheel anyways to aid steering. If it is too little, it would just slip when they tried to turn. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One possibility is weight and balance related- all jetways have a little 'shoe' that detects if the door is about to contact the jetway floor. If this is the case, it either lowers the jetway or sets of some alarm. The weight shift, while not enough to tip the aircraft over, combined with a high jetway position could have triggered the shoe and they might have waited for the gangway to readjust accordingly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IxF6G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://acesflorida.tripod.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://acesflorida.tripod.com/&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;She might also just have noticed something that required a few seconds of waiting, such as somebody walking up the stairs with prams stored in the cargo hold for the family that just disembarked. Reading up on the OPs comments that she was cabin focused, maybe she just spotted some bag in the luggage rack that was unclaimed and wanted to make sure nobody forgot stuff while deplaning, hence holding up the cabin until it was claimed.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-25T13:20:59.670" LastActivityDate="2015-05-25T13:20:59.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15063" PostTypeId="1" AcceptedAnswerId="15066" CreationDate="2015-05-25T13:17:23.340" Score="4" ViewCount="3718" Body="&lt;p&gt;I'd like to buy a scanner to listen to Air Traffic Control (e.g. Tower, Approach, etc.). It would be used mostly at either Washington National [DCA], Dulles [IAD], or Baltimore [BWI]. Would I need a digital or analog scanner to hear these transmissions? Thanks!&lt;/p&gt;&#xA;" OwnerUserId="8621" LastEditorUserId="790" LastEditDate="2015-05-25T13:26:53.617" LastActivityDate="2015-05-25T18:00:46.657" Title="Do I need a digital or analog scanner to listen to Air Traffic Control?" Tags="&lt;radio-communications&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15064" PostTypeId="2" ParentId="15037" CreationDate="2015-05-25T17:14:26.567" Score="2" Body="&lt;p&gt;ICAO regulations allow two-engine aircrafts to fly over oceanic routes (they must have a Ram Air Turbine - RAT) so such a plane - certified as ETOPS, Extended-range Twin-engine Operational Performance Standard - must be safe. Anyway I can agree with other answers stating that if you have to loose an engine it is better to have 3 other. &lt;/p&gt;&#xA;" OwnerUserId="8399" LastActivityDate="2015-05-25T17:14:26.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15066" PostTypeId="2" ParentId="15063" CreationDate="2015-05-25T18:00:46.657" Score="5" Body="&lt;p&gt;The voice communications for air traffic control is all &lt;strong&gt;analog&lt;/strong&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Airband&quot;&gt;AM to be specific&lt;/a&gt;). A scanner that works in that frequency range on AM should be fine. Although a switch to digital has been considered, there is just too much coordination and investment required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good reference to find the right frequencies is &lt;a href=&quot;http://www.airnav.com/airport/KBWI&quot;&gt;AirNav&lt;/a&gt;. It will list all the frequencies for an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another good reference for many frequencies, not just airports, is &lt;a href=&quot;https://www.radioreference.com/apps/db/?aid=1113&quot;&gt;RadioReference&lt;/a&gt;. The database there will tell you exactly how each channel is transmitted, so you know what type of radio you will need to listen to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also keep in mind that ATC transmissions are line-of-sight, so you will have to be close to a ground station to hear it. The &quot;rubber duck&quot; antenna included with a lot of scanners is fine but a better antenna will help to improve reception. Also, military aircraft use a higher frequency range, and a lot of cheaper scanners will not receive this.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-05-25T18:00:46.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15068" PostTypeId="1" AcceptedAnswerId="15073" CreationDate="2015-05-25T21:48:01.197" Score="6" ViewCount="1117" Body="&lt;p&gt;For most full services on EU/US airlines, the permitted weight of each of the checked baggage allowance is 32kg. It is similar for the routes operated by non-EU/US airlines, even though their overall checked baggage allowance is more than that. What are the reasons behind that?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="7670" LastEditDate="2015-05-26T03:19:25.817" LastActivityDate="2015-05-26T03:19:25.817" Title="Why EU/US airline checked baggage allowance limited at 32kg?" Tags="&lt;usa&gt;&lt;weight-and-balance&gt;&lt;airlines&gt;&lt;eu&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15069" PostTypeId="1" AcceptedAnswerId="15077" CreationDate="2015-05-25T22:42:46.523" Score="18" ViewCount="2172" Body="&lt;p&gt;Often an ATS will warn you about other aircraft: when you're taxying and need to give way, or for land-after (and other conditional) clearances, or to warn of traffic in the area you're flying in. Usually they do this by naming the type of the traffic, and often you need to positively confirm whether you have the traffic in sight. For example:-&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;G-ABCD, report departing Squirrel in sight&quot;&lt;br&gt;&#xA;  &quot;Affirm, traffic in sight, G-ABCD.&quot;&lt;br&gt;&#xA;  &quot;G-ABCD, behind the Squirrel, cross runway 18 behind, report vacated.&quot;&lt;br&gt;&#xA;  &quot;Behind the Squirrel, cross runway 18, wilco, G-ABCD.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What if the type of aircraft you're warned about is one you don't know? In an area with lots of vintage or experimental aircraft, you might not even know whether to look for a fixed-wing or a helo. I wouldn't want to say I have the traffic in sight if there's a risk I'm not looking at the same aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;G-ABCD, report departing Squirrel in sight&quot;&lt;br&gt;&#xA;  &quot;The what? Is there wildlife on the runway? G-ABCD&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is there a standard way to explain the situation and disambiguate? Failing that, is there a concise way that will not be misunderstood over noisy radios?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;(For the benefit of other readers who wouldn't recognise &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurocopter_AS350&quot; rel=&quot;noreferrer&quot;&gt;a Squirrel&lt;/a&gt;: it's a helicopter, and the local police operate one out of Cambridge. It was the first obscure-sounding aircraft name I could think of to use as an example.)&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="65" LastEditDate="2015-06-10T18:29:09.873" LastActivityDate="2017-07-29T11:52:48.863" Title="What if you don't recognise an aircraft ATC is telling you about?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15070" PostTypeId="2" ParentId="15011" CreationDate="2015-05-26T00:06:45.793" Score="0" Body="&lt;p&gt;A young man jumped from a plane :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theglobeandmail.com/news/national/nunavut-man-who-jumped-from-plane-identified/article1196251/&quot; rel=&quot;nofollow&quot;&gt;The Globe and Mail&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;The Beechcraft King Air 200 turpoprop aircraft was flying at about 23,000 feet at the time of the incident.&quot;&lt;/p&gt;&#xA;" OwnerUserId="8627" LastActivityDate="2015-05-26T00:06:45.793" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15071" PostTypeId="2" ParentId="15069" CreationDate="2015-05-26T02:25:51.883" Score="8" Body="&lt;p&gt;While I understand what you worry about this is a skill that comes with both time and experience. For what it's worth it's far more important that you know there is an aircraft there than you can tell its make and model. As you fly more you will learn the common ones just by seeing them around the airport and hearing other pilots talk about them. There will always be situations where they may call out an aircraft you don't know but I would not ask for clarification if you have the aircraft in sight. Another reason to call out the make and model is for speed reasons. If you are flying say a Mooney (a fast little plane) on down wind and there is a Piper Cub ahead of you turning base now you are going to want to extend your downwind to give him space (although the tower may call this for you anyway). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's say you hear the controller call:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Number 2 behind Blohm &amp;amp; Voss BV turning base now, cleared to landing runway 24&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you can see a plane turning base you can respond: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Traffic in sight, #2 cleared to land runway 24&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you can find a plane where the controller says it should be I would think you are OK. That being said if there are 2 planes, and you only see one you need to report what you see. If you are not sure which unknown model it is, report the location, not the make and model. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="8282" LastEditDate="2017-07-29T11:52:48.863" LastActivityDate="2017-07-29T11:52:48.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15072" PostTypeId="2" ParentId="15068" CreationDate="2015-05-26T02:26:05.237" Score="5" Body="&lt;p&gt;Because people have to handle your luggage by hand, which is quite a hard job. &#xA;Heavier luggages would pose a health threat for them, putting even more stress on their back. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I once flew with a heavier (&gt;32kg) luggage on a Seoul-Taipei flight and the ground staff was not pleased at the checking counter...&lt;/p&gt;&#xA;" OwnerUserId="4105" LastActivityDate="2015-05-26T02:26:05.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15073" PostTypeId="2" ParentId="15068" CreationDate="2015-05-26T02:44:27.580" Score="11" Body="&lt;p&gt;To add to Antzi's answer it is most likely about worker safety. Your question is where do the 50lbs/23kg and 70lbs/32kg numbers come from. The current answer for US based airports would be the recommendations of the Occupational Safety and Health Administration (OSHA). Here &lt;a href=&quot;https://www.osha.gov/dts/osta/otm/otm_vii/otm_vii_1.html#appendix5&quot;&gt;is a link&lt;/a&gt; to their current lifting standards. There is a neat worksheet down at the bottom for calculating the weight a worker should lift based on the types of movements they have to perform, distances traveled, angles bent. It is a system based on multipliers whose base limit on a normal lift is 51lbs/23.4kg. Then 70lbs/32kg would amount to the multipliers all working out to 1.4 which is again a nice round number. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also speculate that at some points these numbers made it into union contracts for ground workers but I have no actual information on that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I couldn't find were the OSHA regulations that were in force when IATA first enshrined 23 and 32kg into their rules. It is perhaps a bit disappointing that the current OSHA regulations to not have a &quot;max lift&quot; number but their interest is in reducing injury and a single very heavy lift is apparently less damaging than repetitive above average lifts. &lt;/p&gt;&#xA;" OwnerUserId="2329" LastActivityDate="2015-05-26T02:44:27.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15074" PostTypeId="2" ParentId="15008" CreationDate="2015-05-26T03:54:15.317" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.theairlinepilots.com/forumarchive/b777/b777memoryitemsandlimitations.pdf&quot; rel=&quot;nofollow&quot;&gt;This link&lt;/a&gt; says 38 knots for the 777.&#xA;&lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Limitations_(B777).html&quot; rel=&quot;nofollow&quot;&gt;This link&lt;/a&gt; says 25 knots for the 777 autoland system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.b737.org.uk/limitations.htm&quot; rel=&quot;nofollow&quot;&gt;This site&lt;/a&gt; says for the:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;737-200, crosswind limit is 31 knots; &lt;/li&gt;&#xA;&lt;li&gt;for the 737-300 thru -500, 35 knots; &lt;/li&gt;&#xA;&lt;li&gt;for the 737-600 thru -900, 36 knots; and &lt;/li&gt;&#xA;&lt;li&gt;for the 737-600 thru -900 with winglets, 33 knots.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-26T03:54:15.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15077" PostTypeId="2" ParentId="15069" CreationDate="2015-05-26T05:56:55.050" Score="15" Body="&lt;p&gt;To add to &lt;a href=&quot;https://aviation.stackexchange.com/a/15071/572&quot;&gt;Dave's answer&lt;/a&gt;, if traffic is pointed out to you which you are unfamiliar with, ask for clarification. ATC or FIS will have a good understanding of aircraft types and speeds, especially in radar environments the speed will be available as groundspeed (GS).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FIS: DELFF, traffic information, 3 o'clock, 4 miles, same altitude, Mooney Bravo, passing right to left.&lt;br&gt;&#xA;  PIC: DELFF, unfamiliar with aircraft type.&lt;br&gt;&#xA;  FIS: DELFF, traffic is a low wing aircraft, 100kt groundspeed&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-26T08:42:28.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15078" PostTypeId="1" AcceptedAnswerId="15080" CreationDate="2015-05-26T06:38:12.690" Score="6" ViewCount="1147" Body="&lt;p&gt;In largest airport a ground radar is used to handle safely aircrafts on taxiways and on runways, which should be the characteristics of this kind of radar ? What about its range and bearing resolution ? &lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="19" LastEditDate="2015-05-27T20:39:15.743" LastActivityDate="2015-05-28T07:18:14.617" Title="What is the resolution of airport ground radars?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;radar&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15079" PostTypeId="1" AcceptedAnswerId="15081" CreationDate="2015-05-26T08:21:45.053" Score="6" ViewCount="1599" Body="&lt;p&gt;I was just reading about &lt;a href=&quot;http://www.energyquest.ca.gov/how_it_works/air_conditioner.html&quot;&gt;Aircraft Conditiong Systems&lt;/a&gt; and found that, the A.C. mechanism begins with compressor in the engine. Do these compressor also work the way in which AC/Refrigerator's compressor do? If they do, then &lt;a href=&quot;http://aetinc.biz/newsletters/august-2009&quot;&gt;Freon Gas Leaks&lt;/a&gt; should be something happening atleast once in a long period .. They are pretty common with household Air conditioning system.So, does this happens? I have never really heard of something like this happening to an aircraft.. &lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2018-05-24T02:41:01.250" Title="Do Freon gas leaks occur in Airplane conditioning systems as well?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15080" PostTypeId="2" ParentId="15078" CreationDate="2015-05-26T08:46:20.487" Score="3" Body="&lt;p&gt;It's been a while since my last lessons on radars, but..&lt;br&gt;&#xA;The pulse length and the pulse repetition frequency play key roles in radar min and max ranges. The pulse the radar sends must be short enough to end (and the radar switch to detection mode) before the reflection returns.&lt;br&gt;&#xA;To give a rough example, if the pulse length is 2 ms, the theoretical minimum range would be equal to pulse distance in 1 ms (1 there and 1 back).  The pulse travels at light speed, so you can calculate the distance there.&lt;br&gt;&#xA;Note that the pulse lengths differ a lot depending on radars, and presumably none of the are 1 ms long.&lt;br&gt;&#xA;Free quote from the book &lt;em&gt;Understanding Radar Systems&lt;/em&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pulse length of 3 µs, which is a fairly typical pulse length for a&#xA;  long-range airborne surveillance radar, would give a theoretical range&#xA;  resolution of 450 m. However, other factors such as signal processing&#xA;  degrade the resoution, and in the given case the resolution would be around 750 m. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note again, that radars are designed to serve a specific purpose, for example a long-range surveillance radar emphasizes range over resolution.&lt;br&gt;&#xA;What it comes to fighters, most modern fighters have &lt;a href=&quot;http://en.wikipedia.org/wiki/Active_electronically_scanned_array&quot; rel=&quot;nofollow&quot;&gt;AESA radars&lt;/a&gt; instead of pulse radars, which work continuously and handle the signal differently.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="524" LastEditDate="2015-05-27T10:27:54.463" LastActivityDate="2015-05-27T10:27:54.463" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15081" PostTypeId="2" ParentId="15079" CreationDate="2015-05-26T08:49:20.937" Score="12" Body="&lt;p&gt;Large aircraft use &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_cycle_machine&quot; rel=&quot;noreferrer&quot;&gt;air conditioning packs (air-cycle machines)&lt;/a&gt; which uses only air, compressors and heat exchangers to cool/heat the air. There is no freon involved.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="64" LastEditDate="2015-05-26T21:21:29.220" LastActivityDate="2015-05-26T21:21:29.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15082" PostTypeId="1" AcceptedAnswerId="15085" CreationDate="2015-05-26T09:21:53.947" Score="9" ViewCount="2877" Body="&lt;p&gt;This question focus on airliners but is not restricted to Airbus and Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft, there are a lot of audible warning (usually working along with visible warning). This include auto-pilot disengaged, stall, GPWS, wrong flaps configuration, low energy, ... (I'm not aware of all audible warning that are implemented)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given one of this warning, is the sound associated to this warning the same in different aircraft? For example, does a GPWS warning sound the same in Boeing, Airbus, Embraer,...? &lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="524" LastEditDate="2015-05-26T12:13:07.617" LastActivityDate="2015-05-27T07:40:51.757" Title="Are the audible warning standardized?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15083" PostTypeId="2" ParentId="13927" CreationDate="2015-05-26T09:27:11.007" Score="7" Body="&lt;p&gt;Advanced Surface Movement Guidance and Control System (A-SMGCS) provides controllers (eventually pilots and  vehicle  drivers)  with  situational &#xA;awareness on the movement area and  normally  consists of three type of sensors. Surface movement radar, MLAT and ADS-B. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/ju0KT.png&quot; alt=&quot;ASMGS Components&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The kind of information is displayed to the controller is dependent on what are the sensors used and the capability of aircraft and vehicles on the ground.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;If the A-SMGCS is equipped with Surface Movement Radar (SMR) it can display the moving vehicles and aircraft on the maneuvering area. (except in areas where tracking is inhibited ) to the controller. But manual correlation is required to identify the target.&lt;/li&gt;&#xA;&lt;li&gt;If ASMGCS is ADS-B capable, controllers display will show Aircraft or vehicle  Identification (ACID), Essential Flight Plan details like destination etc and type of aircraft also in addition to the exact location of the aircrat or vehicle. For this to work, Aircraft/vehicle should be ADS-B capable.&lt;/li&gt;&#xA;&lt;li&gt;using  MLAT (Multilateration ) ASMGCS system displays postion and ACID and other FPL details to the controller if the aircraft SSR transponder is in operating mode. System correlate the transponder code with the flightplan.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pfxSq.png&quot; alt=&quot;SMR Radar track &quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending upon the level of ASMGCS operation , it can also display the taxiway route, SID, Runway assigned etc to the controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the target is obtained from ADS-B or MLAT then it is called a cooperative sensor target. It will be displayed in a different symbol.&lt;/p&gt;&#xA;" OwnerUserId="8633" LastEditorUserId="679" LastEditDate="2015-05-26T10:53:05.020" LastActivityDate="2015-05-26T10:53:05.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15084" PostTypeId="2" ParentId="15082" CreationDate="2015-05-26T10:48:54.347" Score="5" Body="&lt;p&gt;No, the exact sound of a warning is not regulated across aircrafts. (By the way, &quot;normalize a sound&quot; refer to a special process in audio mixing.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the autopilot disengage sound in Airbus is &lt;a href=&quot;https://www.youtube.com/watch?v=ASkk9GudWWk&quot;&gt;very distinct&lt;/a&gt;. Airbus and Boeing has different &lt;a href=&quot;https://www.youtube.com/watch?v=Ok18QiPkL1o&quot;&gt;altitude callout sounds&lt;/a&gt; as well &lt;em&gt;(500, 400, 300, 200, 100, 50, 20, 10. retard. retard.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even sounds within planes from the same manufacturer are different. The &lt;a href=&quot;https://www.youtube.com/watch?v=YFQ2XRIsbK4&quot;&gt;fire warning in a Boeing 737&lt;/a&gt; sounds like a physical fire bell, while that on a Boeing 777 is an electronic &quot;beep beep beep&quot; sound. The same applies to other sounds like takeoff configuration warning and Master Caution.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-05-26T10:48:54.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15085" PostTypeId="2" ParentId="15082" CreationDate="2015-05-26T13:37:15.130" Score="12" Body="&lt;p&gt;General alerting sounds are chosen by the manufacturer of the cockpit systems. Stall warnings, autopilot disconnect alerts, fire alarms etc. are all not standardised, with the exception of the words spoken by the GPWS/TAW and TCAS system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whilst the exact sounds of these two systems are not standardised in the sense that a standard .wav file is to used by all manufacturers, the phraseology in their aural alerts is standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Ground Proximity Warning System (GPWS)/ Terrain Awareness Warning System (TAWS) will have to issue an aural warning 'PULL UP, PULL UP' if the aircraft is approaching terrain, and 'GLIDESLOPE' when the aircraft is deviating far below the glideslope. Also the cautions ('SINKRATE.', 'TERRAIN.', 'DON'T SINK.', 'TOO LOW, GEAR.', 'TOO LOW, FLAPS.', 'TOO LOW, TERRAIN.' and 'FIVE HUNDRED.')&lt;sup&gt;1&lt;/sup&gt; are standardised. Whether it is a male, female or robotic voice is up to the manufacturer of the system, but the words are uniform across all systems. Additional cautions and aural alerts are allowed as long as they are clear and unambiguous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same holds for TCAS; 'TRAFFIC, TRAFFIC.', 'CLIMB, CLIMB.', 'DESCEND, DESCEND.', 'INCREASE CLIMB,', 'INCREASE DESCENT,', 'REDUCE CLIMB,', 'REDUCE DESCENT.', 'CLIMB, CLIMB NOW.', 'MAINTAIN VERTICAL SPEED, MAINTAIN.', 'LEVEL OFF, LEVEL OFF.' (supersedes &quot;ADJUST VERTICAL SPEED, ADJUST), 'MONITOR VERTICAL SPEED.', 'CROSSING.' and 'CLEAR OF CONFLICT' are all standard phrases which have to be implemented in this exact wording(&lt;sup&gt;2&lt;/sup&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgtso.nsf/0/d6ad0eee7a2261cf86257a300053602c/$FILE/TSO-C151c.pdf&quot; rel=&quot;nofollow&quot; title=&quot;FAA TSO C151C&quot;&gt;FAA TSO C151c&lt;/a&gt; Table 4-1 (pages 16 -- 18)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; RTCA DO-185B, Minimum Operational Performance Standards for&#xA;Traffic Alert and Collision Avoidance System II (TCAS II)&#xA;Version 7.1, Volume I section, 2.2.6.3: Aural annunciations)&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="753" LastEditDate="2015-05-27T07:40:51.757" LastActivityDate="2015-05-27T07:40:51.757" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15087" PostTypeId="1" AcceptedAnswerId="15093" CreationDate="2015-05-26T15:25:40.693" Score="21" ViewCount="12981" Body="&lt;p&gt;On a modern aircraft carrier, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_deck#Angled_flight_deck&quot;&gt;the landing area is not aligned with the axis of the ship&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given this part of the ship needs to be asymmetric, why do most (if not all) angled flight decks point to the left side of the ship (and not the right)? Is there any advantage to favor this side?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1696" LastEditDate="2015-05-27T22:33:57.667" LastActivityDate="2015-06-23T05:01:07.337" Title="Why is the landing area of an aircraft carrier angled to port side, not starboard?" Tags="&lt;aircraft-carrier&gt;" AnswerCount="8" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15088" PostTypeId="2" ParentId="15087" CreationDate="2015-05-26T15:33:15.473" Score="4" Body="&lt;p&gt;&lt;strike&gt;The answer lies in the same &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_deck#Angled_flight_deck&quot; rel=&quot;nofollow noreferrer&quot;&gt;article section you referenced&lt;/a&gt;. There are two animations there, on the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wreUJ.gif&quot; alt=&quot;Animation&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in this animation, the longer runway is for landing. If an aircraft could not stop, it needs to take off again. That is the reason aircraft carriers have the landing strip angled so that it will not interfere with aircraft which are about to take off or the parked ones.&lt;/strike&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15087/why-is-the-flight-deck-of-an-aircraft-carrier-heading-to-port#comment35064_15087&quot;&gt;Simon clarifies&lt;/a&gt; that OP is specifically asking about why landing runways are not pointed towards the right/starboard side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_carrier#Flight_deck&quot; rel=&quot;nofollow noreferrer&quot;&gt;While the island&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt; is usually built on the starboard side of the fight deck, the Japanese aircraft carriers Akagi and Hiryū had their islands built on the port side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason might be more of a tradition that reasons behind it. Please note that there very few aircraft carriers in the world, and only a few countries have it. So there is not a big competition or difference of standards in this area.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: The superstructure of a carrier (such as the bridge, flight control tower) are concentrated in a relatively small area called an island&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-05-26T16:08:31.030" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15089" PostTypeId="2" ParentId="8580" CreationDate="2015-05-26T15:34:28.913" Score="5" Body="&lt;p&gt;For the first step try &lt;a href=&quot;http://www.calculatoredge.com/electronics/lineofsight.htm&quot; rel=&quot;nofollow&quot;&gt;this line of sight calculator&lt;/a&gt;. Line of sight is an imaginary line that exists between two objects. Radio transmissions require a clear path between antennas known as radio line of sight. Formula:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Line of Sight = √ (2*height1) + √ (2*height2) in Miles&lt;/p&gt;&#xA;" OwnerUserId="8637" LastEditorUserId="4474" LastEditDate="2015-07-25T18:23:28.393" LastActivityDate="2015-07-25T18:23:28.393" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15090" PostTypeId="2" ParentId="15087" CreationDate="2015-05-26T15:48:14.287" Score="8" Body="&lt;p&gt;The innovation of the angled flight decks gives several key advantages:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most notably, it is far safer for carriers to land aircraft on angled decks that point away from the superstructure, ground personal and aircraft parked forward.  This greatly reduces mishaps involving aircraft crashing into people and objects on the deck.  &lt;em&gt;The reason the landing area is canted to the left is because the superstructure is on the right.  For clarification, the superstructure is always on the right.  The carrier landing pattern has remained constant for decades so that every approach to the carrier will remain as constant as possible.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: To take it a step further, when the decision was first made to place the superstructure on the right side it was likely because the carrier pattern was already a left hand pattern.  Its worth noting that the standard traffic pattern is a left pattern as well, and a superstructure on the left side, during a left hand pattern, would partially obscure the landing area from view during the downwind and approach turn.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-05-26T17:20:34.400" LastActivityDate="2015-05-26T17:20:34.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15091" PostTypeId="1" AcceptedAnswerId="15094" CreationDate="2015-05-26T16:04:38.567" Score="5" ViewCount="5303" Body="&lt;p&gt;How is fuel stored in a tanker aircraft? What arrangements are made to make the aircraft liquid tight? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-05-26T16:51:20.013" Title="How is fuel stored in a tanker aircraft?" Tags="&lt;aircraft-design&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ClosedDate="2015-05-26T18:58:17.160" ContentLicense="CC BY-SA 3.0" />
  <row Id="15092" PostTypeId="2" ParentId="15087" CreationDate="2015-05-26T16:05:26.480" Score="1" Body="&lt;p&gt;&lt;strong&gt;Why always the port side?&lt;/strong&gt;  There's no technical reason so it can only be convention - for example several carriers operating together could steam in the same direction and launch their aircraft in the same direction too.  The aircraft would be on (approximately) parallel paths so would not have to take special action to avoid each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also occurred to me that the bridge would be always on the right/starboard, docking facilities might be arranged to take advantage of this...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/HMS_Hermes_%2895%29&quot; rel=&quot;nofollow&quot;&gt;HMS Hermes&lt;/a&gt; was apparently the first carrier with the &quot;control tower&quot; (Island) to starboard.  This may be the origin of the convention.  The link states that pilots prefer a port turn on an aborted landing...&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2015-05-26T17:10:22.617" LastActivityDate="2015-05-26T17:10:22.617" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15093" PostTypeId="2" ParentId="15087" CreationDate="2015-05-26T16:12:54.897" Score="32" Body="&lt;p&gt;Farhan's answer covered why the deck is angled in the first place. As far as why the landing area of the deck points left instead of right, this is for several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Angling to port makes the most use of the deck area behind the catapults. Angling starboard would require the catapults to be shifted left off the centerline of the carrier (yes, the carrier does have two additional catapults on the port side, but these can't be used while the carrier is retrieving aircraft, which is more often than you'd think as the carrier maintains regular patrols).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Angling the landing strip toward the &quot;island&quot; (conning tower) of the carrier just doesn't sound like a good idea when you say it. That goes double when you realize the carrier is underway while you're trying to land on it, and therefore you have to lead the landing strip a little. If you don't, you'll end up &quot;behind&quot; the ship and the landing strip. With the landing strip angled to port, a plane on a &quot;lagging&quot; approach (lined up &quot;behind&quot; where the carrier's going to be at touchdown) will have a relatively clear path off to port for a wave-off. Angled to starboard, a plane that's &quot;lagging&quot; the carrier would be pointed right at the tower.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It would be possible to mirror the entire deck layout; island to port, landing area angled starboard. The reason the island is on the starboard side is primarily convention; all U.S. Navy aircraft carriers ever built have been either flush-decked or have had the island to the right. That's thus a familiar sight picture for naval pilots across all eras, and easy to train to. A new carrier design doesn't get the luxury of a whole new crew trained an entirely different way; the Navy's been training pilots since 1910, they've been landing planes on boats since 1927, and they'll do it they way they've been doing it for 88 years, thank you very much. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Imperial Japanese Navy commissioned two carriers, &lt;em&gt;Akagi&lt;/em&gt; and &lt;em&gt;Hiryu&lt;/em&gt;, with island-left designs, fielded with the idea that the island-left carrier would sail in formation with an island-right carrier in the same flag group, with opposing traffic patterns that didn't conflict. This procedure never materialized in practice; most carrier groups in both Japanese and U.S. fleets ended up with a single carrier due to their high cost and lower total number, a pattern that continues today, and even when two (or more) carriers were close enough to be called part of the same naval group, they typically maintained a wide enough spacing to permit a left-hand pattern for both ships.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-23T05:01:07.337" LastActivityDate="2015-06-23T05:01:07.337" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15094" PostTypeId="2" ParentId="15091" CreationDate="2015-05-26T16:44:39.403" Score="10" Body="&lt;p&gt;You might be surprised to learn that most refueling tankers hold a relatively small percentage of their total fuselage volume in fuel. The reason why is simple; a plane stuffed to the gills with fuel would be so grossly overloaded it wouldn't make it off the runway. Tankers, therefore, can double as medium transports with little modification, as they have a sizable upper deck which is more or less empty space when serving as a tanker, but which can ferry troops, light vehicles or other materiel from Stateside bases to various theaters (a dedicated heavy transport like the C-5 or C-17 would be used for transporting large units or for specialized troop transport like airbornes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the layout of the KC-135 Stratotanker:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k7wJX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my knowledge, all of this fuel is available both to power the plane and to refuel other aircraft, however the plane would likely draw primarily from the wing tanks for flight, as this is the &quot;standard&quot; configuration for the 707 the KC-135 is built on. Transport of the fuel from these tanks to the refueling systems would be accomplished with an integrated pump and pipe system that could move fuel from anywhere to anywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bulk of the fuel load, as you can see, is contained in four &quot;body tanks&quot; totaling over 144,000 pounds of fuel. For comparison, the F-15E strike fighter can carry a maximum, with CFTs and 3 droptanks, of just 35,550 pounds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These tanks are lined with plastic bladders, which contain the fuel (so the entire fuselage doesn't have to be leak-proof which is much more difficult and expensive to ensure) and also allows the bladder to collapse as the fuel inside it is depleted, reducing the volume of air in direct contact with the fuel, thus reducing the vapor hazard. AFAIK the wing tanks do not have these bladders, but they're much smaller spaces overall and more easily accessed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Separating the fuel into multiple tanks has several advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The tanker is still serviceable with one or more of the tanks unable to carry fuel (leak in the bladder, pump failure, etc).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sloshing of the fuel in the tanks has less effect on the weight distribution of the aircraft. Imagine trying to take off with a full Olympic swimming pool in your cargo hold; any pitch up or down will cause several tons of weight to move &quot;downslope&quot;, unbalancing the aircraft (probably fatally).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel can be pumped between these tanks to fine-tune or &quot;trim&quot; the aircraft's weight distribution and handling characteristics, a process known as &quot;tank trimming&quot; which is more aerodynamically efficient than elevator trimming.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-26T16:51:20.013" LastActivityDate="2015-05-26T16:51:20.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15095" PostTypeId="1" AcceptedAnswerId="15121" CreationDate="2015-05-26T16:51:45.373" Score="2" ViewCount="322" Body="&lt;p&gt;I'm not a pilot, but have interest in the question from a safety perspective, as a skydiver and drop zone operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read the &lt;a href=&quot;https://www.redskyventures.org/doc/other-poh/PacificAerospace-PAC750XL-POH.pdf&quot; rel=&quot;nofollow&quot;&gt;POH&lt;/a&gt; of &lt;a href=&quot;http://en.wikipedia.org/wiki/PAC_P-750_XSTOL&quot; rel=&quot;nofollow&quot;&gt;PAC P-750 XSTOL&lt;/a&gt;, and tried reading a bit about the calculations, but could not make it out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the parameters below, how is the minimum runway length is calculated for PAC P-750 XSTOL?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parameters:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pac 750 XSTOL&lt;/li&gt;&#xA;&lt;li&gt;15 knots cross wind 90&lt;/li&gt;&#xA;&lt;li&gt;0° flaps&lt;/li&gt;&#xA;&lt;li&gt;6500 LBS TOW&lt;/li&gt;&#xA;&lt;li&gt;Runway is 1500 feet above MSL&lt;/li&gt;&#xA;&lt;li&gt;ISA +10°&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8638" LastEditorUserId="65" LastEditDate="2015-05-26T16:58:38.077" LastActivityDate="2015-05-27T09:34:25.057" Title="How minimum runway length is calculated for PAC P-750 XSTOL?" Tags="&lt;safety&gt;&lt;runways&gt;&lt;skydiving&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15096" PostTypeId="1" AcceptedAnswerId="15097" CreationDate="2015-05-26T18:56:43.523" Score="0" ViewCount="442" Body="&lt;p&gt;What if a pilot was forced to land in a tailwind? Would this be possible and what is the maximum tailwind an aircraft can handle?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2015-05-26T19:23:26.353" Title="What would happen if a pilot tried to land with a tailwind?" Tags="&lt;landing&gt;&lt;pilots&gt;&lt;tail-dragger&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-05-26T19:50:00.873" ContentLicense="CC BY-SA 3.0" />
  <row Id="15097" PostTypeId="2" ParentId="15096" CreationDate="2015-05-26T19:14:06.250" Score="4" Body="&lt;p&gt;Your landing rollout will be longer, your groundspeed will be faster and you will stress the brakes more than a landing with less tailwind.  The same can be said for choosing calm winds over a headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The jet I flew and many others have a limitation for maximum tailwind of 10 kts and it isn't unheard of to request an opposite direction landing (e.g. with a tailwind) if the tailwind is acceptable, the runway is long, and there is no conflicting traffic when it is convenient for the operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were forced to make a landing with a tailwind exceeding your limitations then the situation is probably an emergency and you'll want a longer than normal runway.  There is an increased threat of a brake fire, but in an emergency &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_rescue_and_firefighting&quot; rel=&quot;nofollow&quot;&gt;ARFF&lt;/a&gt; will be following you down the runway and they'll take care of it.  The tailwind landing only really becomes a problem if the runway isn't long enough (overrun) or if the tailwind is so strong that the maximum wheel speed is exceeded (loss of directional control or worse). &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-05-26T19:23:26.353" LastActivityDate="2015-05-26T19:23:26.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15101" PostTypeId="2" ParentId="15079" CreationDate="2015-05-26T21:30:33.107" Score="1" Body="&lt;p&gt;While transport-category jets &lt;a href=&quot;https://aviation.stackexchange.com/a/15081&quot;&gt;tend to use air-cycle machines like ratchet freak mentioned&lt;/a&gt; some light airplanes are available with &quot;standard&quot; (freon heat-pump) air conditioners.&lt;br&gt;&#xA;These have the same refrigerant-leak problems as your typical car air conditioner as seals age, pipes crack, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These air conditioners are also not particularly popular accessories because they add weight and mechanical complexity to the aircraft (I don't think I've ever seen a plane with one installed in person, though I know a few folks over on the Piper forums who have the factory air conditioning in their planes).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-26T21:30:33.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15102" PostTypeId="2" ParentId="14978" CreationDate="2015-05-26T21:56:20.940" Score="5" Body="&lt;p&gt;The most obvious answer is &quot;Gravity&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To some extent this is &quot;normal&quot; in a low-wing aircraft with a nose-mounted engine and a fuel pump drawing fuel from the wing tanks into the engine: As the nose pitches up the fuel needs to run &quot;uphill&quot; to get to the engine - that's more work for the fuel pump, which might not maintain full &quot;straight-and-level&quot; fuel pressure.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see something similar in a Piper Cherokee in an aggressive climb, particularly if you are only using the engine-driven (mechanical) fuel pump: The fuel pressure typically drops when you pitch past ~15-20 degrees nose-up. The drop isn't much, but it's noticeable if you're looking for it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pressure drop makes you uncomfortable turning on the electric boost pump(s) may reduce or eliminate it, but as long as the fuel pressure remains in the aircraft's normal operating range it's probably not a cause for concern. You should however become familiar with how much the pressure tends to drop in a climb: A larger drop than &quot;normal&quot; may indicate a problem with the (mechanical) fuel pump which you would want to have your mechanic investigate.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-05-26T21:56:20.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15103" PostTypeId="1" AcceptedAnswerId="15110" CreationDate="2015-05-26T22:06:33.140" Score="11" ViewCount="1562" Body="&lt;p&gt;Example: I'm in a 172 tailed N1234A, on a pleasure hop between Hicks Field and Addison, circling around DFW International to the north, flying at 1500ft within DFW's Mode C veil under VFR (so I'm squawking 1200). The approach direction for the day also happens to be the north (this is common; prevailing winds in the area tend to be southerly). I'm staying outside DFW's airspace and therefore have not checked in with DFW Approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I'm about to pass underneath &quot;Area B&quot; of DFW's space (which begins at 2000ft between 10 and 13nm from the airport sweeping across the northern approach), there is a 747 approaching low in the class B umbrella. It will pass above and in front of me, but still too close for their comfort, and so ATC wants to verify that I see the jumbo out my left window and perhaps suggest I descend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Was flying under the approach traffic of DFW my first mistake? Should I instead be heading around south (which would be a really big detour as I'd need to avoid Love Field's portion of Class B) or just contacting DFW Approach for clearance through Class B space?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Am I in the wrong for not having made prior contact with DFW Approach or Fort Worth Center in these circumstances, even though I'm operating VFR in class E/G space? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Should I even be this close to Class B in the first place (I'm 500 feet below it and 2 miles outside the surface footprint)? If not, what's a better altitude and range for me to have planned for? Outside 13NM from the airport, I'd be under Area H which starts at double my altitude, 3000 ft, but would also require me to enter or avoid Alliance's Class D space, and it'd take me quite a bit out of my way (since it's just for fun and logging hours, I might as well just touch and go at DTO if it'll be this much hassle to avoid DFW).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Would DFW or FW Center even bother trying to inform me of the situation, assuming I stay safely underneath Class B space and the 747 stays safely in it? One would think, being in contact with the 747, they could simply tell the jumbo to maintain minimum 2500 or 3000ft until 10nm out to maintain 1000ft minimum vertical separation, but my experience with boats says that if someone should yield right of way in this situation, it's the smaller craft (me).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Here are the title questions. How would DFW attempt to contact me? What frequency would I be expected to be tuned to? The emergency frequency is of course 121.5, but during normal flight along this path I could conceivably be listening to Fort Worth Center (122.65), DFW Approach (124.3), Addison ATIS or Approach, etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What would they say that I'd be expected to respond to, and how should I respond? I'm guessing they'd say something to the effect of &quot;unknown VFR craft bearing 350 range 12 altitude 15, acknowledge and identify&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-05-26T22:55:06.637" LastActivityDate="2021-04-05T12:19:38.350" Title="How would ATC try to establish contact with a VFR craft?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;&lt;radio&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15104" PostTypeId="2" ParentId="15087" CreationDate="2015-05-26T22:13:32.367" Score="25" Body="&lt;p&gt;Why is the deck of an aircraft carrier angled to the left?  Because the island is on the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is the island on the right?  Because studies on the &lt;a href=&quot;https://en.wikipedia.org/wiki/HMS_Furious_(47)&quot;&gt;HMS &lt;em&gt;Furious&lt;/em&gt;&lt;/a&gt; showed that &lt;a href=&quot;https://en.wikipedia.org/wiki/HMS_Eagle_(1918)#Construction_and_conversion&quot;&gt;pilots tended to turn left&lt;/a&gt; during an aborted landing.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2015-05-26T22:13:32.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15105" PostTypeId="2" ParentId="15103" CreationDate="2015-05-26T22:41:04.590" Score="5" Body="&lt;p&gt;Normally they wouldn't even try to get in contact with you.  It is easier and probably blocks less time on the frequency to talk to someone they have established contact with than to someone who they don't know which frequency he's on.  What you said in point 4 is correct, they don't have control over you as you're VFR and you're not even in their controlled airspace.  Bigger aircraft don't have right of way over smaller aircraft. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/934f0a02e17e7de086256eeb005192fc!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR-AIM Sec 91.113&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What they will probably say to the 747 is something like &quot;American 123, traffic, 3 o'clock 2500 feet, same direction, type unknown.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If AA123 acknowledge that they see you, &quot;American 123, maintain visual separation&quot;, otherwise &quot;American 123, maintain 3000 feet for traffic&quot;&lt;/p&gt;&#xA;" OwnerUserId="390" LastEditorUserId="7532" LastEditDate="2019-01-12T19:03:07.780" LastActivityDate="2019-01-12T19:03:07.780" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="15106" PostTypeId="2" ParentId="14982" CreationDate="2015-05-27T00:15:27.190" Score="4" Body="&lt;p&gt;Glider designers use flaperons frequently because the chord is so narrow and the wingspan so long that the ailerons have to span the length of the wing to have sufficient roll authority. This leaves no room to add flaps, so they are incorporated in to the ailerons. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-05-27T13:30:33.587" LastActivityDate="2015-05-27T13:30:33.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15107" PostTypeId="2" ParentId="9052" CreationDate="2015-05-27T00:24:59.030" Score="1" Body="&lt;p&gt;On Pipers (Cherokee, Cherokee Six), the flaps had step areas on the inboard ends. When retracted, they were essentially locked in position. When extended to the first notch, they were spring loaded in such a way that they could be pushed down to expose the hinges and linkages for inspection from above. The pre-flight routine would include setting the flaps to 1 notch to facilitate inspection during walk-around, but otherwise keep them retracted until pre-take-off. So a reason for keeping retracted would be to help with boarding.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-27T00:24:59.030" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15108" PostTypeId="2" ParentId="8966" CreationDate="2015-05-27T01:26:51.610" Score="9" Body="&lt;p&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;: &lt;a href=&quot;https://www.ecfr.gov/cgi-bin/text-idx?SID=730d487d2f972a9573b1a770033a2e97&amp;amp;mc=true&amp;amp;node=20180627y1.62&quot; rel=&quot;nofollow noreferrer&quot;&gt;83 FR 30232&lt;/a&gt;, updated the requirements of &lt;a href=&quot;https://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=730d487d2f972a9573b1a770033a2e97&amp;amp;mc=true&amp;amp;n=sp14.2.61.a&amp;amp;r=SUBPART&amp;amp;ty=HTML#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.51(g)&lt;/a&gt; where an instructor is &lt;b&gt;NO LONGER&lt;/b&gt; required to be present in order to log time in a flight simulator or aviation training device for instrument currency. Note that an instructor is still required in order to log simulator time that counts towards a rating or certificate and that a &lt;i&gt;FAA approved&lt;/i&gt; device must be used. This particular change was effective July 27, 2018.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;i&gt;The following is no longer accurate, but retained for historical purposes:&lt;/i&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has been quite a bit of confusion in this area due to language in a preamble to the 2009 &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/72DFC1B3808D2CB486257656006E4D11?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;Final rule on Pilot, Flight Instructor, and Pilot School Certification&lt;/a&gt;, which implied that an instructor was not required for instrument currency and &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2014-title14-vol2/pdf/CFR-2014-title14-vol2-sec61-51.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.51(g)(4)&lt;/a&gt; which says that an instructor must be present. I believe this all started with an email to John King of King Schools, where Lance Nuckolls at AFS-810 stated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...approved uses for a BATD and an&#xA;  AATD are governed by § 61.4(c) and the LOA. The LOA states that an&#xA;  authorized instructor must certify the instructional use. Simply&#xA;  satisfying the requirements of § 61.57(c)(2) is not considered&#xA;  instructional use, therefore &lt;strong&gt;an authorized instructor does not need to&#xA;  be present&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Emphasis added)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough, the PDF of this email is no longer available on the King Schools &lt;a href=&quot;http://www.kingschools.com/flight-simulators/redbird/docs/approved-instrument-recency-experience-without-a-flight-instructor.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;website&lt;/a&gt;. Instead users are redirected to the Rebird TD page where it now implies that an instructor is required to maintain instrument currency.  A copy of the message text is available &lt;a href=&quot;http://www.airlinepilotforums.com/flight-schools-training/14933-logging-ifr-currency-simulator.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this was too much of a good thing, so someone had to get the lawyers involved! In &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2010/keller-1%20-%20(2010)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Keller (2010)&lt;/a&gt;, the FAA's Office of the Chief Counsel made their opinion known:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...in order to log the time an instructor must be present to observe&#xA;  an individual using a flight training device or flight simulator to&#xA;  maintain instrument recency experience.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This position was reasserted in &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2014/stewart%20-%20(2014)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stewart (2014)&lt;/a&gt;, which references the Keller letter and explicitly cites 14 CFR 61.51(g)(4).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we now have a situation where the FAA doesn't agree with itself! Whose opinion wins?  The lawyers', of course! In &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2010/perry%20-%20(2010)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Perry (2010)&lt;/a&gt;, the Chief Counsel's office states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...where two interpretations address an identical scenario and reach&#xA;  an inconsistent result, the interpretation issued by the Assistant&#xA;  Chief counsel for Regulations takes precedence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some additional background:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the author is referring to the Redbird Flight Simulations' &lt;a href=&quot;http://simulators.redbirdflight.com/certification/faa&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA approval page&lt;/a&gt; where it states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When using the Redbird to maintain instrument currency an instructor&#xA;  is not required to be present. This has been discussed with and&#xA;  confirmed by AFS-810. A current Instrument pilot is not required to&#xA;  have an instructor on board the real aircraft to log approaches in&#xA;  IMC, therefore it follows that the FAA trusts a pilot to correctly log&#xA;  an approach preformed in the Redbird.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On its face, this statement appears to be in direct conflict with FAA's legal interpretation. Of course, one could try challenging this position (an interpretation is an opinion, after all), but it won't be me!&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2018-08-07T20:49:29.253" LastActivityDate="2018-08-07T20:49:29.253" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15109" PostTypeId="2" ParentId="14500" CreationDate="2015-05-27T02:32:18.553" Score="9" Body="&lt;p&gt;Changing the status quo always takes time. Aircraft have been painted almost since the dawn of flight (and the very earliest aircraft were still doped to stretch the fabric over the skeleton). That is reason in itself for antique and historical aircraft and their replicas to be painted instead of vinyled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, most liveries come factory-installed right alongside the host of other options available. Most high-end private jets as well as the big commercial ones are built-to-order inside and out, including the customer's brand livery. That livery, much like the factory color of a car, often stays with the plane its entire life, with only routine touch-ups performed as a normal part of maintenance. Refitting a fleet with new livery and/or interiors, until very recently, wasn't done often; Southwest's &quot;Canyon Blue&quot; livery change was noteworthy, as was AA's fleet rebadging, and neither airline bothered repainting planes that are on the way out anyway; the aging Super 80s as well as the 757s and some 767s are still in classic AA silver livery and will be that way until they're retired from the fleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, aftermarket vinyl livery's market share is already somewhat limited; people buying a new jet will get their livery applied at the factory, and people buying a used jet and wanting the livery changed significantly are in for quite an expense even if they choose vinyl; the old painted livery will usually have to be removed and the plane refinished in a new base coat before the new vinyl decals are applied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also venture, having seen aftermarket vinyl applied to other vehicles, that even if the utmost care is taken in applying it, the decal is always going to look like a decal, and it may not age well even with a meticulously-maintained airframe. If you're paying \$65 million (base price) for a G650, \$25,000 (or even \$100,000) for custom livery is a drop in the bucket. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, your 172 or Piper Cherokee sport pilot might be very interested in personalizing his plane on this kind of budget, as would an aircraft club of part-owners, or your self-employed commercial pilot like a crop duster or charter bush pilot. Vinyl on small planes thus makes more sense; however, it's still a significant expense, and a purely cosmetic one, so it's still rare to see a plane's factory paint scheme change significantly aftermarket, except for niche uses like aerobatics and stunt flying.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-10T18:04:23.063" LastActivityDate="2015-07-10T18:04:23.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15110" PostTypeId="2" ParentId="15103" CreationDate="2015-05-27T03:17:04.777" Score="20" Body="&lt;p&gt;Long story short, ATC has no reason to contact you but if they were to try they'd probably use 121.5 (see below). You're not in their airspace and the whole purpose of that airspace is to ensure separation, so as long as you remain clear of it they won't be concerned about you although they'll probably report your position to the 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your specific questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;That's your decision as PIC and no one else can make it. But I wouldn't spend much time in a zone where I'm at high risk of a wake turbulence encounter.&lt;/li&gt;&#xA;&lt;li&gt;No, there is no requirement for you to be in contact with ATC in that airspace so you're not wrong. It would be good to get flight following if possible, but that's optional and might not be available anyway.&lt;/li&gt;&#xA;&lt;li&gt;It's hard to say what &quot;too close&quot; means and it could change depending on the time of day, if you're thinking about traffic. Again, this is something that you as PIC have to determine.&lt;/li&gt;&#xA;&lt;li&gt;They won't try to contact you since you're outside the class B and they have no reliable way to contact you anyway. And considering wake turbulence again, &quot;too close for &lt;em&gt;their&lt;/em&gt; comfort&quot; is probably more like too close for &lt;em&gt;your&lt;/em&gt; comfort :-) Aircraft size isn't a consideration for right of way (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1113&quot;&gt;14 CFR 91.113&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;They won't for the reasons above. And they also can't know if you have a working radio, which frequency you're on etc. But they would probably try 121.5 because &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/us_restrictions/fdc_notams/pdf/FDC%20NOTAMS%204-4386%20and%204-0811.pdf&quot;&gt;a current FDC NOTAM&lt;/a&gt; states that you should be monitoring it if you can:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ALL AIRCRAFT OPERATING IN UNITED STATES NATIONAL AIRSPACE, IF CAPABLE,&#xA;  SHALL MAINTAIN A LISTENING WATCH ON VHF GUARD 121.5 OR UHF 243.0.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; also suggests and encourages all pilots to monitor it (e.g. section 6-2-4).&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;6&quot;&gt;&#xA;&lt;li&gt;It's hard to say, the FAA's &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC instructions&lt;/a&gt; don't cover this situation (or I couldn't find it). But giving a specific bearing is unlikely (a bearing from what?) because you might not have the equipment to verify it so perhaps &quot;12 miles north of DFW at 1500ft&quot; would be more likely for the position part.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Of course, if ATC really, desperately, urgently needs to contact you - like if you fly straight through the class B without a clearance - then they can always request an interception. That would really ruin your day, so monitoring 121.5 if you can is probably a good idea.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-27T03:17:04.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15111" PostTypeId="1" CreationDate="2015-05-27T03:28:55.047" Score="1" ViewCount="119" Body="&lt;p&gt;In response to the case of MH370, an idea which has been floated is that of a device to transmit an aircraft's GPS position. Not specified is whether such a device would be operable by the flight crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among the scenarios suggested to account for the aircraft &quot;going dark&quot; and its apparent flight path is intentional action by someone aboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To provide aircraft position (or any other parameter) reporting free of any possible interference by anyone aboard the aircraft would require installation of equipment inoperable by and therefore in a location inaccessible to anyone (crew included) during flight. That means such equipment could never be powered down while the aircraft is in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have there been/are there currently any regulations which would prohibit the installation of such a device for any reason - e.g. fire safety, possible interference with other radio equipment essential to safe flight (navigation, communication)?&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-27T06:36:11.373" Title="Do regulations permit an airliner be equipped with a radio transmitter which cannot be controlled by the crew?" Tags="&lt;radio&gt;&lt;electrical-system&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ClosedDate="2015-05-27T07:26:29.820" ContentLicense="CC BY-SA 3.0" />
  <row Id="15112" PostTypeId="2" ParentId="15111" CreationDate="2015-05-27T04:34:32.877" Score="0" Body="&lt;p&gt;To my knowledge, there hasn't been any regulations, but airlines are still using the manual transponder because of the current SOPs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is part of all airlines' SOP to toggle the transponder to STBY while at the gate and departing. One of the reasons is to reduce the amount of radio waves present. Other reasons include the display of departing aircrafts while at the gate. Usually, it would be switched to TA/RA during the Before Takeoff Checklist (Airline SOPs vary. I don't speak for all). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question, there's no regulations that I know of, so it's more of the airlines' choice. When I had a conversation with a long haul pilot, he mentioned that a couple of times the transponder would be left on TA/RA while at the gate, which means yes, it's do-able, but will airlines adapt to it, probably not at the moment. In the future, perhaps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope that answers your question, or at least helped a bit. &lt;/p&gt;&#xA;" OwnerUserId="8566" LastActivityDate="2015-05-27T04:34:32.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15113" PostTypeId="2" ParentId="15037" CreationDate="2015-05-27T04:47:39.307" Score="3" Body="&lt;p&gt;The more engines you have, the better off you are if one engine fails; however, the more likely it is that one will fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines, like many things, are rated in terms of &quot;mean time between failures&quot; or MTBF. For aircraft engines, MTBF is relatively high (tens of thousands of hours when properly maintained), but they do still fail in relatively unassuming situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's simple probability that, given a nonzero chance for a given engine to fail, the chance that at least one engine will fail is the combined chance for each particular engine to fail. So if the engine type used on a 747 has a 1/1000 chance to fail on a particular flight (the actual chance is much lower, in the tens of millionths), there is a 4/1000 = 1/250 chance of at least one engine on the plane failing during that flight. If the two engines on a 737 each had the same chance for failure, the chance of one engine failing on the flight are half those of one engine failing on the 747, because there are half the number of engines that could fail. In MTBF terms, we can say the mean time between single engine failures on a 747 is half that of a 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, we see that increasing the number of engines, all other things being equal, actually &lt;em&gt;increases&lt;/em&gt; the chances of something going wrong. However, the pilot of a twin-engined craft, though he may be twice as likely to experience an engine failure compared to the pilot of a single-engine craft, is going to have a much better day when it happens than the single engine pilot will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big question that really has to be asked is, how many engines can the plane fly on, and how many more than that number does it have? Jets like the DC-10 and 727 were marketed for their relatively high fault-tolerance; they could maintain level flight at low altitude on only one engine, having lost the other two, and on the 727 it didn't really matter which one was still running as they were all so close to the centerline. The 747 requires at least two of its four engines to maintain level flight (see British Airways Flight 9 in 1982, during which all four engines quit mid-flight due to ingestion of volcanic ash; restarting one engine slowed the rate of descent but it took two to level off).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, primarily for fuel efficiency reasons, passenger jets are designed with as few engines as they need; engines are most efficient at a specific point in their power curve, and you design the aircraft to cruise efficiently at that power output of its engines. This is why the 737 (and newer jets like the 777 and 787) doesn't have four engines; it doesn't need them, because the 737 is a fifth the weight and the engines it does have are more efficient than the 747's.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T17:17:21.323" LastActivityDate="2015-07-23T17:17:21.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15114" PostTypeId="2" ParentId="12070" CreationDate="2015-05-27T06:08:38.140" Score="1" Body="&lt;p&gt;The MEL is NOT a list of equipment that must be installed and operable for the aircraft to be considered airworthy. The correct definition is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MEL is a list of aircraft equipment that can be inoperable PRIOR to dispatch. MEL items are only applicable before your flight is dispatched. Once you are in the air you need to consult the aircraft QRH.&lt;/p&gt;&#xA;" OwnerUserId="8645" LastActivityDate="2015-05-27T06:08:38.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15115" PostTypeId="2" ParentId="15111" CreationDate="2015-05-27T06:36:11.373" Score="2" Body="&lt;p&gt;All equipment on board needs to be interruptable, either by direct control input (turning it off) or via circuit breaker. This especially holds true for equipment that is capable of broadcasting or emitting radio waves, such as radio telephony equipment or the transponder. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the transponder for any reason became damaged and started to send incorrect replies to ground interrogation, it needs to be shut off in order to not confuse ATC systems or other aircraft's TCAS. Electronic or electric systems also need to be shut down in case of eletrical fires or other safety hazards to the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-05-27T06:36:11.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15116" PostTypeId="1" CreationDate="2015-05-27T07:12:56.410" Score="1" ViewCount="26252" Body="&lt;p&gt;Can I do pilot training courses even after age 26 ?&lt;/p&gt;&#xA;" OwnerUserId="8646" LastEditorUserId="3386" LastEditDate="2015-05-27T07:27:38.107" LastActivityDate="2015-05-28T15:30:14.247" Title="What is the maximum age limit for getting a pilot licence?" Tags="&lt;flight-training&gt;" AnswerCount="3" CommentCount="2" ClosedDate="2015-05-27T15:12:41.783" ContentLicense="CC BY-SA 3.0" />
  <row Id="15117" PostTypeId="1" AcceptedAnswerId="15122" CreationDate="2015-05-27T08:22:38.453" Score="7" ViewCount="18970" Body="&lt;p&gt;&lt;sub&gt;&lt;sup&gt;I am not a pilot - just a student &amp;amp; play Ace Combat sometimes&lt;/sup&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intrigued by the words Starboard &amp;amp; Port-side I researched why these words are used instead of the simple ones, I found that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Port is derived from the practice of sailors mooring ships on the left side at ports in order to prevent the steering oar from being crushed. &lt;sub&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Port_and_starboard&quot; rel=&quot;noreferrer&quot;&gt;src&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, quite notably:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Since port and starboard never change, they are unambiguous references that are independent of a mariner’s orientation, and, thus, mariners use these nautical terms instead of left and right to avoid confusion. When looking forward, toward the bow of a ship, port and starboard refer to the left and right sides, respectively.&lt;sub&gt;&lt;a href=&quot;http://oceanservice.noaa.gov/facts/port-starboard.html&quot; rel=&quot;noreferrer&quot;&gt;src&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I see both the reasons are derived upon the concerns of the marine world - so why do we use them in aviation world?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is specially interesting if we consider the fact that flying machines can manevur in all 3D, newbies (me) tend loose track of &lt;em&gt;my VS. plane's&lt;/em&gt; left &amp;amp; right when not in level flight. Then why the added confusion?&lt;/p&gt;&#xA;" OwnerUserId="8215" LastActivityDate="2016-12-02T04:47:35.453" Title="Why is port-starboard terminology used in aviation?" Tags="&lt;flight-controls&gt;&lt;navigation&gt;&lt;terminology&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15118" PostTypeId="2" ParentId="15116" CreationDate="2015-05-27T08:43:59.570" Score="4" Body="&lt;p&gt;As far as I know there are no maximum age restrictions on getting a pilots license anywhere in the world. Many countries have a &lt;strong&gt;minimum&lt;/strong&gt; age restriction for getting a license, that usually does not prevent pilot training from taking place. 26 is fine, in fact 76 is fine as long as you pass whatever medical is required. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-05-27T08:43:59.570" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15119" PostTypeId="1" CreationDate="2015-05-27T09:02:38.160" Score="1" ViewCount="516" Body="&lt;p&gt;I was wondering whether a microburst can occur at high altitudes?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="1467" LastEditDate="2015-05-27T10:34:02.067" LastActivityDate="2019-03-27T19:48:37.877" Title="Can microbursts occur at high altitudes?" Tags="&lt;weather&gt;&lt;wind&gt;&lt;turbulence&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15120" PostTypeId="2" ParentId="15119" CreationDate="2015-05-27T09:21:02.187" Score="6" Body="&lt;p&gt;Strong downbursts of air are possible at high levels also, for example in Cumulonimbus-clouds. However I wouldn't characterize them as microbursts, since the change of airflow direction is an equally dangerous and defining factor in microbursts.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2H6nA.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2H6nA.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.weather.gov.hk/aviat/amt_e/cause/microburst_e.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;weather.gov.hk&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;p&gt;The head/tailwind parts don't exist at higher altitudes and you would experience the downdraft merely as turbulence.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-03-27T19:48:37.877" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15121" PostTypeId="2" ParentId="15095" CreationDate="2015-05-27T09:34:25.057" Score="1" Body="&lt;p&gt;You can't, at least not on the basis of the POH you linked. Taking off with 0° flaps for that aircraft is outside the POH limitations chapter.&lt;/p&gt;&#xA;&lt;p&gt;2.20 Flap Limitations:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Approved flap ranges.&lt;/p&gt;&#xA;&lt;p&gt;TAKEOFF FLAP: 20°&lt;/p&gt;&#xA;&lt;p&gt;LANDING FLAP: 40°&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;4.27 Amplified Procedures - Normal Takeoff):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A wing flap setting of 20°  is recommended for all takeoffs. 20° flap&#xA;will provide the best takeoff performance. The Normal Takeoff&#xA;technique is to be used for Short Field operations and is the&#xA;technique used to derive the performance data in Section 5.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-27T09:34:25.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15122" PostTypeId="2" ParentId="15117" CreationDate="2015-05-27T09:44:31.407" Score="15" Body="&lt;p&gt;&lt;strong&gt;It isn't&lt;/strong&gt; (much).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ships are the most similar thing to aircraft that existed before them, so it made sense that aviation took over many terms and conventions from seafaring (the pilot in command is called &lt;em&gt;captain&lt;/em&gt;, the &lt;em&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Cockpit_%28sailing%29&quot;&gt;cockpit&lt;/a&gt;&lt;/em&gt; is the flight &lt;em&gt;deck&lt;/em&gt;, distances and speeds are given in &lt;em&gt;nautical miles&lt;/em&gt; and &lt;em&gt;knots&lt;/em&gt; etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However since there is no physical port in an aircraft to serve as reference (most aircraft have doors on &lt;em&gt;both&lt;/em&gt; sides), everybody has to learn to give the sides relative to the direction of flight and then it does not make sense to teach them new words when they already know “left” and “right”. So “port” and “starboard” are only used where there is a naval tradition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know British military aviation (RAF) used it (in wartime stories and documents it is common, but according to Simon's comment it is not common any more) and the US Navy uses it with ships, but I don't know to what extent they apply it to aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it remains popular in simulator games, presumably because it is catchy and unusual and using jargon makes people feel special.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2015-05-27T15:38:13.123" LastActivityDate="2015-05-27T15:38:13.123" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15123" PostTypeId="2" ParentId="15087" CreationDate="2015-05-27T10:08:18.660" Score="1" Body="&lt;p&gt;Prop planes used to (and still do today!) drift  to the side opposite to the propeller rotation direction during take-off. And while it's true that the first carriers were flat-decked (no island, no banking) many pilots begin their training with prop planes.And there were some crazy 50's turboprop carrier operated planes like the A-1 in times immemorial when jets were not quite established as the future of sea-borne aviation.&#xA;One might be forgiven to assume that the first &quot;island&quot; carrier designs originating back then had something to do with allowing a quick take-off with the rudder straight compensating for the drift by angling the deck. And as the layout was proven and found good...Just my two cents.&lt;/p&gt;&#xA;" OwnerUserId="8648" LastActivityDate="2015-05-27T10:08:18.660" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15124" PostTypeId="2" ParentId="15078" CreationDate="2015-05-27T10:55:54.353" Score="5" Body="&lt;p&gt;For surface movement radars (SMR) operating in the 9 - 9,5 GHz band, the pulse length is typically in the order of 40ns. This is equivalent to 12 meters. That would bring the theoretical minimum range to 6 if we ignore transmitter / receiver switching overhead time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice there is no need for such a short range. Instead a pulse train is transmitted before the antenna is switched from the transmitter to the receiver. This allows the radar to increase the accuracy by averaging multiple reflections, at the price of an increase in minimum range. Typical minimal range will be in the order of 100 meters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other SMR systems use continuous wave radar and have a transmitter and receiver antenna in the radar head. These systems don't require to switch between transmitting and receiving and don't have a minimum range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The range resolution is in the order of 3 meters, equivalent to the pulse rise time of about 10ns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The azimuth resolution of a typical SMR is in the order of 0.25 degrees, which is equivalent to 10 meters at 2 km distance. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Apart from primary radar there are other classes of surveillance systems in use for airport surface detection. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Secondary surveillance radar (SSR) lacks the accuracy of the SMR and&#xA;can only see transponders. But combined with the primary radar allows&#xA;for identification of aircraft on the airport surface (i.e. putting&#xA;identification labels on the aircraft's primary radar reflection).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Multilateration (MLAT) systems also rely on transponders but are more&#xA;accurate than SSR for surface monitoring. These systems require a large number of receivers and are susceptible for radio reflections from buildings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ADS-B relies on the aircraft (or airport vehicle) transmitting its&#xA;position, speed and heading.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-28T07:18:14.617" LastActivityDate="2015-05-28T07:18:14.617" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15125" PostTypeId="2" ParentId="15087" CreationDate="2015-05-27T11:45:14.263" Score="1" Body="&lt;p&gt;At this point in time it's because all carriers in commission have their islands to starboard, so all carriers will &lt;em&gt;continue&lt;/em&gt; to have their islands to starboard. From a naval engineering standpoint there's no reason to prefer having the island to starboard vs. port, but from a pilot training standpoint it's important to minimize the differences between carriers in order to minimize pilot confusion.&lt;/p&gt;&#xA;" OwnerUserId="1095" LastActivityDate="2015-05-27T11:45:14.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15126" PostTypeId="1" AcceptedAnswerId="15131" CreationDate="2015-05-27T12:11:19.280" Score="6" ViewCount="1796" Body="&lt;p&gt;The recent &lt;a href=&quot;http://www.bbc.co.uk/news/world-africa-32890312?ocid=socialflow_facebook&quot;&gt;AF953 near-miss incident&lt;/a&gt; as reported by the BBC describes the ground collision alert warning triggering, preventing a &lt;a href=&quot;http://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot;&gt;CFIT&lt;/a&gt; by the plane. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An initial incident report published by BEA said an automated warning,&#xA;  saying &quot;Pull up&quot;, was activated. The plane then ascended quickly from&#xA;  9,000ft (2,743m) to 13,000ft (3,962m) to avoid crashing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;BEA did not say how close the plane came to Mount Cameroon.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How close does a plane have to come within the ground (as measured by the radar) before the warning triggers? Does this number vary significantly between aircraft models, or is there some legislated fixed value for the distance?&lt;/p&gt;&#xA;" OwnerUserId="5537" LastActivityDate="2015-05-28T00:52:45.143" Title="How close does a plane have to come to the ground before triggering the ground collision alert?" Tags="&lt;safety&gt;&lt;accidents&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15128" PostTypeId="1" CreationDate="2015-05-27T12:33:27.300" Score="5" ViewCount="1317" Body="&lt;p&gt;How much power is needed by aircraft In Flight Entertainment systems during flight if they operate all the devices connected in the cabin?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-06-02T17:49:37.397" LastActivityDate="2015-06-02T17:49:37.397" Title="How much power is needed by aircraft IFE systems during flight?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15129" PostTypeId="2" ParentId="15116" CreationDate="2015-05-27T12:55:52.130" Score="2" Body="&lt;p&gt;To expand a bit on @GdD's answer, a number of aeronautical regulatory bodies, including the FAA, do not specify a maximum age for flight training or executing the privileges of Pilot-In-Command &lt;em&gt;under most circumstances&lt;/em&gt;; as long as you hold a valid medical, you're in the clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, your individual circumstances may be different. There are some exceptions to this even in the civilian world, such as maximum age limits when flying for certain airlines (such as the age 65 rule for Part 121 operations in the US). If you're in a part of the world where airlines offer cadet programs and such, they may also impose maximum age limits for applicants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're interested in military flying, the armed services may also have additional restrictions on maximum age for flight training; the USAF for example, had the age of 26 as the upper bound for anyone applying for a pilot slot about 5-6 years ago, and armed forces the world over have similar restrictions in place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to @SSumner for providing a &lt;a href=&quot;http://usmilitary.about.com/od/joiningthemilitary/l/blpilotage.htm&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; with the current age limits for US military pilot training.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-05-28T15:30:14.247" LastActivityDate="2015-05-28T15:30:14.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15130" PostTypeId="2" ParentId="15126" CreationDate="2015-05-27T13:08:08.907" Score="2" Body="&lt;p&gt;The GPWS doesn't use radar but rather a terrain database and a GPS position. Alert are given based on time before collision rather than a fixed distance, since a distance that provides inadequate reaction time for a fast aircraft might be unreasonably large for a slow one, and it is important with warning systems like this that all alerts be valid ones, not false alarms that one gets in the habit of ignoring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Times can vary by system, but I think it's generally about 1 minute away you get a &quot;caution&quot; message, and 30 seconds away, a &quot;pull up&quot; warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Link to Wikipedia article -- gives some GPWS theory but doesn't address algorithms: &lt;a href=&quot;http://en.m.wikipedia.org/wiki/GPWS&quot; rel=&quot;nofollow&quot;&gt;http://en.m.wikipedia.org/wiki/GPWS&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-27T13:08:08.907" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15131" PostTypeId="2" ParentId="15126" CreationDate="2015-05-27T13:08:28.660" Score="6" Body="&lt;p&gt;There are 7 modes of warning&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 1. Large descent rate near terrain. Gear and flap position not a factor in the warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 2. Large closure rate with terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 2A. Occurs for a large closure rate if the flaps are not in the&#xA;landing configuration and glideslope deviation is more than 2&#xA;dots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 2B. Alerts for a large closure rate if the flaps are in&#xA;the landing configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 3. Alerts for a large altitude loss during takeoff or&#xA;during a missed approach with the flaps not in the landing&#xA;configuration or landing gear not down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 4. Alerts when the airplane is too close to the&#xA;terrain and the landing gear or flaps are not in the landing&#xA;configuration&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 4A alert when the landing gear is not&#xA;down and gives the aural messages TOO LOW GEAR at&#xA;low airspeeds, or TOO LOW TERRAIN at high airspeeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 4B alerts when the landing gear is down and the flaps are not in landing configuration and gives the aural messages TOO LOW FLAPS if the airplane is at low airspeed, or TOO LOW TERRAIN at high airspeeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 5 alerts when the airplane goes below&#xA;the glideslope during approach if the landing gear is down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 6 gives aural callouts when the airplane descends through set altitudes with the landing gear down. It gives callouts like MINIMUMS or DECISION HEIGHT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mode 7 gives windshear warnings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every one of these modes is altitude, speed and aircraft configuration dependent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Enhanced GPWS, these triggers are also changed based on the position of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regulatory requirement &lt;a href=&quot;http://www.gpo.gov/fdsys/granule/CFR-2013-title14-vol3/CFR-2013-title14-vol3-sec121-354&quot; rel=&quot;noreferrer&quot; title=&quot;14 CFR 121.354&quot;&gt;14 CFR 121.354&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technical requirements &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/d6ad0eee7a2261cf86257a300053602c/$FILE/TSO-C151c.pdf&quot; rel=&quot;noreferrer&quot;&gt;TSO-151C&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-05-27T14:01:38.550" LastActivityDate="2015-05-27T14:01:38.550" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15132" PostTypeId="2" ParentId="15116" CreationDate="2015-05-27T13:16:42.227" Score="1" Body="&lt;p&gt;It would help if you specify if you are getting the license to fly private or commercially. For private there is no age restriction if you pass your medical, as is the same for commercial. However as mentioned some airlines may prevent you from flying after a certain time. That all being said &lt;a href=&quot;https://www.youtube.com/watch?v=WJk9Skxyi84&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; brings up some good points about starting training later in life (in your 30's). It takes a lot of hours to become a commercial pilot and the later you start training the later you enter the workforce (as with any job). I would think 26 is perfectly fine. Im getting my Private Pilot and started at 23. There are plenty of people at the flight school well over 50 starting their training as well. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-27T13:16:42.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15133" PostTypeId="2" ParentId="9014" CreationDate="2015-05-27T13:36:26.950" Score="20" Body="&lt;p&gt;All those answers are pretty wrong.  One eye..Can't read the instruments.. Aviation ANVS like the ANVS 9's are dual tube.  You focus them to your liking,individually for each eye!  I personally get 20/20 with them and you mount them high and simply look under them to read the instruments! I have over 7,000 hours of single pilot NVG.  They make things safer, easier, and it's just like flying during the day, only everything is green.  Things like towers and wires (powerlines) are actually MORE visible under NVG's.  It usually takes established pilots with zero NVG time only a few hours to adjust.  Nothing to it.&lt;/p&gt;&#xA;" OwnerUserId="8651" LastEditorUserId="8482" LastEditDate="2015-05-27T14:22:43.563" LastActivityDate="2015-05-27T14:22:43.563" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15134" PostTypeId="2" ParentId="15128" CreationDate="2015-05-27T14:22:25.687" Score="1" Body="&lt;p&gt;I don't have specifics but lets extrapolate for a minute (using the Boeing 777-300 for size filled with lets say 500 seats). Assuming you are talking about IFE systems where there is a screen in every seat then you will most likely have &lt;a href=&quot;http://www.varizoom.com/product-p/vzm7.htm&quot; rel=&quot;nofollow&quot;&gt;screens similar to this&lt;/a&gt;. While not exactly what the airplane uses I would think they are similar. The specs for that screen claim it takes &amp;lt;= 8W. Lets round it out and say it takes 8w. Looking at our 500 seats thats 4000W of power. I can only assume there is a computer or two of sorts running those displays, lets say they have 500W (typical desktop supply on the more powerful side) and there are 2 of them. Thats another 1000W so you are at 5000W there. Assuming you have 120V power P=IV thats about 41 Amps of current you will draw from the system. I am running this assumption that all the screens are on at all times as I assume the system is built for that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin lighting is tough as I have no idea how many bulbs they have in there. I know that each seat has its own little lamp so you are looking at 500 little lamps running in the 1W-10W range. So maybe another 2000W for the individual lights. Overhead is tough since you cant really see the individual bulbs. It should also be noted that LED's are becoming more wide spread and draw way less power than traditional incandescent bulbs which will greatly reduce the amount of power drawn by the interior lights. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-27T14:22:25.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15135" PostTypeId="2" ParentId="15128" CreationDate="2015-05-27T14:26:10.700" Score="0" Body="&lt;p&gt;I had a look around but couldn't find too much. This is a competitive industry so they would be inclined not share too much information (a bit like fuel and jet aircraft). The power consumption is probably the top of the iceberg of important things to consider and I imagine manufactures don't want to make their products look unattractive without showing the customer the full scope of what they are buying, such as software capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After much searching, Rockwell Collins were kind enough to &lt;a href=&quot;https://www.rockwellcollins.com/~/media/Files/Unsecure/Products/Product%20Brochures/Cabin/IFE/PAVES%20Broadcast%20in-flight%20entertainment%20system.aspx&quot; rel=&quot;nofollow&quot;&gt;publish&lt;/a&gt; (dated 2013) some information for overhead monitors systems. The media server uses about 80 watts (so a bit more than an average laptop) and the interactive screen to control the content about 20 watts. There is no figures on how much each actual screen uses. Be aware this is for a system that shows the same content on all screens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found to &lt;a href=&quot;http://www.tdipower.com/PDF/white_paper/TW0061.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; that suggests that the power supply draws around 100 watts (that would fit with the suggestion above). Be aware however that it was written in 2008, the year after the first iPad was released and tablet computers (and corresponding expectations) took hold in the public. A lot has happened since then and as stated in the paper newer systems can draw a lot more. Furthermore, power supplies can be shared among multiple seats (the one shown in the paper has &quot;multiple outputs&quot;). This &lt;a href=&quot;http://cdn.intechweb.org/pdfs/28816.pdf&quot; rel=&quot;nofollow&quot;&gt;quite extensive paper&lt;/a&gt; also discusses IFE design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The competition also means that they would like to make the devices as light and efficient as possible. Looking at the &lt;a href=&quot;http://www.panasonic.aero/InflightSystems/XSeries.aspx&quot; rel=&quot;nofollow&quot;&gt;X-Series&lt;/a&gt; from Panasonic (&quot;The world's most popular in-flight entertainment system&quot; quoting themselves) the screen does video decoding and also includes Android compatibility. Aside from the substantially higher price tag, I think it would be a fair estimate to compare the power in the high range for a tablet computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's always good to contrast these figures: If you're going to go providing AC and USB plugs, laptop chargers use in the range of 80 watts and half the passengers on a A320 use a USB plug for their charging their empty gadgets, you're looking at 350 watts.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-05-27T14:26:10.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15136" PostTypeId="1" AcceptedAnswerId="15149" CreationDate="2015-05-27T14:38:34.070" Score="4" ViewCount="1380" Body="&lt;p&gt;I am working on a project to create a mid-size airship having a payload of 25kg. I am in a bit of problem regarding choosing the appropriate landing gear design for it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which design would be better, considering the tradeoff with weight, which is a very important parameter. Is using 2 wheels to stabilize my system further worth its weight penalty, or a single wheel would be better like Zeppelin?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would appreciate any  help.&lt;/p&gt;&#xA;" OwnerUserId="3029" LastActivityDate="2015-05-27T19:12:58.843" Title="What are the advantages and disadvantages of having a single castor wheel as compared to 2 wheels in an airship?" Tags="&lt;landing-gear&gt;&lt;airship&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15138" PostTypeId="2" ParentId="15128" CreationDate="2015-05-27T14:40:01.313" Score="1" Body="&lt;p&gt;It depends on how many lights are on, and how much the in-flight entertainment system is in use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cabin Lighting&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;New aircraft exclusively use LED lights&lt;sup&gt;1&lt;/sup&gt; for cabin lights. Compared to incandescent or fluorescent bulbs, LED bulbs much less power. If I'm not mistaken, LED bulbs are being used on aircraft lighting (at different levels) for 20 years or so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In-flight Entertainment&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power consumption of IFE systems is &lt;a href=&quot;http://www.tdipower.com/PDF/white_paper/TW0061.pdf&quot; rel=&quot;nofollow&quot;&gt;mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most IFE system PSUs fall into the power range of less than 100W,&#xA;  although some newer IFE products require higher power solutions of 300&#xA;  watts, or more.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Please note that an IFE system is not just the monitor a passenger sees, but it has other &lt;em&gt;hidden&lt;/em&gt; components too, which require power as well.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Biggest example is &lt;a href=&quot;http://a380airbus.com/airbus-a380-cabins/&quot; rel=&quot;nofollow&quot;&gt;A380&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A380’s interior illumination system uses bulbless LEDs in the&#xA;  cabin, cockpit, and cargo decks. The LEDs in the cabin can be altered&#xA;  to create an ambience simulating daylight, night, or intermediate&#xA;  levels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-27T14:40:01.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15139" PostTypeId="2" ParentId="15117" CreationDate="2015-05-27T14:40:33.957" Score="7" Body="&lt;p&gt;The greatest value of port and starboard over left and right is when you have people facing multiple directions. port and starboard are always vehicle centric directions (as are fore and aft) and remain constant regardless of which way you are facing. In this context right and left therefore apply to the people (or other things that have left sides like consoles) in the vessel. Therefore it is perfectly reasonable for a flight attendant to turn left, starboard and north all at the same time. A pilot should not try to do this while working. This distinction is less useful if the craft is not big enough for those inside to move, and more useful when you our vessel is large enough to have a map of the interior.&lt;/p&gt;&#xA;" OwnerUserId="2910" LastActivityDate="2015-05-27T14:40:33.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15140" PostTypeId="1" CreationDate="2015-05-27T14:45:54.623" Score="4" ViewCount="1345" Body="&lt;p&gt;How much power is used by cabin lighting systems during flight when all the lights are ON?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="6886" LastEditDate="2015-07-03T03:13:17.410" LastActivityDate="2015-07-07T04:35:55.920" Title="How much power is used by cabin lighting systems during flight?" Tags="&lt;airliner&gt;&lt;cabin-design&gt;&lt;electrical-system&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15141" PostTypeId="2" ParentId="15140" CreationDate="2015-05-27T15:04:37.070" Score="3" Body="&lt;p&gt;Almost all lighting systems installed today use Light Emitting Diodes for weight savings, reduced power use and less maintenance. Compared to other aircraft systems, their power use is pretty insignificant. For the reading lights, I found the following quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passenger reading lights in halogen technology use 11 watts, while the&#xA;  latest LED products use only one watt. &lt;a href=&quot;http://www.aviationtoday.com/av/issue/feature/New-LEDs-Better-Mood_81053.html#.VWXZ-OeX2Rs&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The actual ceiling ceiling lighting power consumption seems more difficult to find. &lt;a href=&quot;http://saab.com/globalassets/publications-pdfs/support-and-services/regional-aircraft/interior-led-lighting-product-sheet-web-version.pdf&quot; rel=&quot;nofollow&quot;&gt;SAAB&lt;/a&gt; in a brochure for converting fluorescent to LED lights for their SAAB 340 &amp;amp; 2000 models states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Power consumption is reduced from 8 watts per 12 inch tube to just 5,1&#xA;  watts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.emteq.com/lighting/#product&quot; rel=&quot;nofollow&quot;&gt;Emteq&lt;/a&gt; suggests savings of around 15% for LED compared to fluorescent lights, so SAAB's suggestion would be a bit more. This &lt;a href=&quot;http://utcaerospacesystems.com/sites/decrane/Documents/LED%20Strip%20Light.pdf&quot; rel=&quot;nofollow&quot;&gt;manufacturer&lt;/a&gt; quotes 10W for a 16-inch (40cm) LED strip running off the 28V aircraft DC system. Needless to say, power consumption depends on the wattage of light installed.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-27T15:20:48.567" LastActivityDate="2015-05-27T15:20:48.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15143" PostTypeId="2" ParentId="11449" CreationDate="2015-05-27T16:21:28.040" Score="11" Body="&lt;p&gt;I'd like to augment Chris's answer by noting that the mechanical issue in question is called &quot;gimbal lock&quot;. It occurs when a three-axis-of-freedom system, such as a gyroscope or compass suspended in two gimbal rings, gets two rings aligned in the same plane. The aligned rings are now &quot;locked&quot; and cannot detect motion in the plane of the rings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can imagine the problem by picturing a telescope (or a gun) on an azimuth-and-elevation mount, trying to track an aircraft flying directly overhead. As the plane approaches, the telescope elevates all the way to 90 degrees, but then to follow the plane, it would have to instantaneously spin around 180 degrees in azimuth. A human can easily solve the problem by turning the telesocpe as fast as possible and reacquiring the target on the far side, but an electronic system would have lost the target by the time it finished rotating. Depending on its complexity, it might not even be able to decide which direction to turn in the first place. The same is true of early gyrocompasses flying directly over the pole.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compasses that suffer from this problem are usually designed to shut down when approaching gimbal lock to avoid damage to the mechanisms. The compass would then have to be reset and manually re-aimed to align with the Earth's rotational axis, which would probably have to wait until the aircraft landed. To avoid the possibility entirely, aircraft are advised to give the pole a wide berth, even though modern gyrocompasses do not suffer from this problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's not to say no aircraft has &lt;em&gt;ever&lt;/em&gt; flown over the poles. Admiral Richard Byrd famously made multiple flights over both the North and South poles, and there's no reason a gyrocompass couldn't be designed with polar travel in mind. (It would risk gimbal lock somewhere else on the planet instead.)&lt;/p&gt;&#xA;" OwnerUserId="8652" LastEditorUserId="8652" LastEditDate="2015-06-02T16:47:46.717" LastActivityDate="2015-06-02T16:47:46.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15144" PostTypeId="2" ParentId="15136" CreationDate="2015-05-27T16:57:54.063" Score="3" Body="&lt;p&gt;Some full-sized airships have three wheels in a tricycle arrangement, such as this &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Modern_airship_gondola.jpg&quot; rel=&quot;nofollow&quot;&gt;wikipedia photo link&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Others have just two, such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Zeppellin_NT_2_amk.JPG&quot; rel=&quot;nofollow&quot;&gt;Zeppelin NT&lt;/a&gt; - one for weight bearing, and a smaller tail wheel which appears to be there to keep the tail from fouling on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd suggest, for the size you're planning, you just go for the minimum possible.  Only worry about wheels if you will need to taxi it or steer it into wind.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-05-27T16:57:54.063" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15145" PostTypeId="2" ParentId="14800" CreationDate="2015-05-27T17:04:06.013" Score="1" Body="&lt;p&gt;I am not sure what you should do, but this company is not EASA 147 certified. &lt;a href=&quot;http://www.google.co.in/url?q=http://easa.europa.eu/system/files/dfu/Foreign_EASA_Part_147_14.pdf&amp;amp;sa=U&amp;amp;ei=JPhlVbbgGM_voAT6sYDQAg&amp;amp;ved=0CA0QFjAB&amp;amp;usg=AFQjCNETIWJpWw4v9Mu5jLAXBJ_xAqiBsw&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-05-27T17:04:06.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15146" PostTypeId="2" ParentId="12407" CreationDate="2015-05-27T17:34:10.220" Score="1" Body="&lt;p&gt;The answer varies from aircraft to aircraft. The newer varities such as the A380 go for a overhaul in about 1200-1500 hours, whereas the B777's go once in 1600-2000 hours of service.When an aircraft goes to overhaul, only then the thrust reversers go to overhaul, because they are an important component of the engine of modern day aircrafts. Though we do not know when will an aircraft retire, so it i difficult to come at a concrete result. But, talking about B747, many airlines are retiring them at the age of 40 years. So, 40 years = 350400 hours. 350400/2000 = 175(Approx.) So, for a B747 the answer should be like 175, and this does not necessarily implies to other aircrafts as well.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-05-27T17:34:10.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15147" PostTypeId="1" AcceptedAnswerId="15148" CreationDate="2015-05-27T18:36:24.333" Score="32" ViewCount="41100" Body="&lt;p&gt;For almost every airline, the captain sits in the left seat, and the first officer on the right.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;We know that in most countries &lt;a href=&quot;http://en.wikipedia.org/wiki/Right-_and_left-hand_traffic&quot;&gt;right-side traffic and some have left-side&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;During training, the student sits in the left seat, and the trainer on the right.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Keeping these two points in mind, why does the captain always sits on left? It is not based on culture (see #1 above), and not on who has more experience&lt;sup&gt;1&lt;/sup&gt; to fly an airplane from both seats.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: I know that there can be a situation when the first officer is more experienced than the captain, but most of the time, it is not the case.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="1360" LastEditDate="2015-06-04T13:14:50.723" LastActivityDate="2019-12-26T05:48:33.130" Title="Why does an airplane captain sit in the left seat?" Tags="&lt;aircraft-design&gt;&lt;airline-operations&gt;&lt;aviation-history&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15148" PostTypeId="2" ParentId="15147" CreationDate="2015-05-27T18:36:24.333" Score="40" Body="&lt;p&gt;There are several reasons, mostly historical, or theories behind this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;After World War I, most airplanes had rotary engines with left turning tendencies because it followed the torque of the engine. Therefore, turning left was easier than turning right. Because of this, pilots considered left turns as more convenient maneuver, and thus more experienced pilot started sitting on the left.&lt;/li&gt;&#xA;&lt;li&gt;Since the early days of aviation, the fact that pilot was sitting on the left, they keep the airplane on the right side along the airway. At that time, pilots often navigate visually following roads and railways. Opposite traffic following the same path then pass each other on the left.&lt;/li&gt;&#xA;&lt;li&gt;Because captain sits on the left, left-hand traffic patterns are more common.&lt;/li&gt;&#xA;&lt;li&gt;In order to avoid a head-on collision, each airplane must turn right. Since the captain sits on the left, they will have an unrestricted view of the other airplane, and therefore can assess the situation easily.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In modern times, almost all airplanes (other than single-pilot airplanes or where one pilot sits behind the other), both seats have full controls to fly the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regulations do not specify which seat should be occupied by the pilot-in-command (PIC) or the Pilot Flying (PF).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that &lt;a href=&quot;https://aviation.stackexchange.com/questions/8177/why-is-the-pic-position-for-helicopters-the-right-seat-rather-than-the-left-sea&quot;&gt;on many helicopters, captains sit on the right side&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bibliography:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.askcaptainlim.com/flying-the-plane-flying-90/1173-why-must-a-captain-sit-on-the-left-side-of-a-plane.html&quot; rel=&quot;noreferrer&quot;&gt;Why a Captain sits on the left side of a plane?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/113400/&quot; rel=&quot;noreferrer&quot;&gt;Why Does The Captain Sit On The Left?&lt;/a&gt; &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.pprune.org/tech-log/437033-why-captain-sits-left.html&quot; rel=&quot;noreferrer&quot;&gt;Why Captain sits on the Left?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-11-04T19:19:36.343" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15149" PostTypeId="2" ParentId="15136" CreationDate="2015-05-27T19:12:58.843" Score="5" Body="&lt;p&gt;Two wheels side-by-side would only be needed if the craft is in danger of tipping over sideways. Airships should stay upright because the lifting gas will still provide most of the lift, and the wheel is only for carrying the remaining load. It can swivel for ground maneuvering when the airship needs to swing into the wind while mooring at the mast, but will neither absorb big &lt;a href=&quot;https://aviation.stackexchange.com/questions/7889/how-much-force-does-a-747-land-with&quot;&gt;landing loads&lt;/a&gt; nor carry the craft at high speed, so it can be kept small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the lower tailfin you should only provide a bumper for unintended ground contact; adding a second wheel would only make sense when the ship touches the ground with both wheels when level. This would be a bad design, however, because maneuvering will be much easier when the lower tail fin provides enough ground clearance to allow pitch angles of approx. 3° - 5°. Note that the lower fin on most Zeppelins was smaller than the upper fin; only the last, less slender ones could afford equally sized fins. In that case, however, you need sufficient propulsion power to keep the cruise speed well above the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11320/longitudinal-stability-of-airships-how-is-the-critical-speed-defined&quot;&gt;reversal speed&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-27T19:12:58.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15151" PostTypeId="2" ParentId="8000" CreationDate="2015-05-27T22:54:13.590" Score="1" Body="&lt;p&gt;The difference between track and heading not only includes wind, but also includes flight in sideslip due to asymmetric drag (eg engine out) or pilot induced steady heading sideslip. It also includes AoA during a turn; extreme case of 90degrees AoB at high AoA.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastActivityDate="2015-05-27T22:54:13.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15152" PostTypeId="2" ParentId="15147" CreationDate="2015-05-27T23:50:40.853" Score="14" Body="&lt;p&gt;In a lot of airplanes (especially the older ones) the pilot sat in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When airframes got bigger, they also got bigger (or more) engines. In the propeller era this also produced a tendency to turn to one side easier than the other, so the drivers found turning that way to be easier (or no choice if you had a problem). If you are sitting in the middle it doesn't matter, if you have to choose a side you want the turn-toward side so you can see the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A big design factor is most of us are right-hand dominant. If you have a 2-seat flight deck in side-by-side arrangement you probably want one set of common controls ( power, prop, mixture, radios etc. ) and the pilot would want to operate them with their dominant hand. You don't need precision control of the stick at the same time you are adjusting the engine or tuning the radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also consider that the USA was a major player in aircraft design, and they drive on the right side of the road (same reason, going back to wagons in the frontier days). Back then the pilot was king, the copilot was a trainee, management buys what the pilot tells them to buy, and the pilot will sit on the left because that's the same place he sits in his car. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once that pattern started we end up being stuck with it. If the pilot sits on the left, they will park with the airport gate on the left and thus the doors are on the left. The next plane on the design board better follow the same conventions, because planes don't have reverse and airports didn't have tugs back then. Next we build jetways to hook up to the left side door, and now passenger cabin design expects the front left door to be the primary entrance - the front right door might not get opened for months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters seat the pilot on the right for exactly the same reason - the pilot is probably right-handed. In a helicopter, the cyclic needs constant, precise input. You typically can't let go of it, ever&lt;sup&gt;1&lt;/sup&gt;. But the collective doesn't require constant attention, and in a 2-seater can be a shared control (mechanically simpler and lighter). The pilot accepts more difficult use of the radios etc. so he can keep it flying right side up.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: In &lt;a href=&quot;https://en.wikipedia.org/wiki/Terminator_2:_Judgment_Day&quot;&gt;Terminator 2&lt;/a&gt;, the T-1000 grows an extra hand in order to fly a helicopter while reloading his weapons. Someone on the effects team did their homework.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="65" LastEditDate="2015-05-28T15:57:17.873" LastActivityDate="2015-05-28T15:57:17.873" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="15153" PostTypeId="2" ParentId="15147" CreationDate="2015-05-28T00:28:23.333" Score="6" Body="&lt;p&gt;In WWI the first European air forces were recruited from cavalry regiments. Largely because flying had been a rich man's hobby and cavalry regiments were mostly recruited by the rich (because they had previously supplied their own horses).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horse mounted right handed soldiers wear their sword on their left side. To mount a horse with a sword hanging down your left leg  you need to mount from the left (to swing your right leg over) so they naturally mounted their aircraft from the same side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Royal Air Force also does't have the rank of sergeant for the same reason. Sergeant originally meant servant (so much has changed...) and a cavalry soldier  was a gentleman who would object to such a low title so cavalry regiments don't have the rank of sergeant. When the cavalry became fliers they took the same tradition with them.&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="65" LastEditDate="2015-06-16T19:57:06.950" LastActivityDate="2015-06-16T19:57:06.950" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15154" PostTypeId="2" ParentId="9764" CreationDate="2015-05-28T00:43:12.107" Score="-1" Body="&lt;p&gt;First of all, as a VFR pilot you are usually always watching weather and the chance that visibility just instantly drops is unlikely.  That being said, you do have some &quot;hood time&quot; when training for your private pilot rating that you will likely fall back on ... but more importantly, if you are flying a modern aircraft, is to rely on autopilot.  Turn the aircraft over to the autopilot, lookup weather conditions around you on your MFD (or call Flight Service and get their advise on where to go); then adjust the heading or punch direct to the destination with the better conditions.  I would also notify ATC of my condition and if things were really bad, declare an emergency.&lt;/p&gt;&#xA;" OwnerUserId="7029" LastActivityDate="2015-05-28T00:43:12.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15155" PostTypeId="2" ParentId="15126" CreationDate="2015-05-28T00:52:45.143" Score="1" Body="&lt;p&gt;It depends on the type of aircraft and the avionics systems onboard.  A STOL aircraft may not give you any warnings at all.  Garmin G1000 systems are entirely configurable to the pilots settings.  I personally have mine set to alert me when I'm at 500ft from any terrain.&lt;/p&gt;&#xA;" OwnerUserId="7029" LastActivityDate="2015-05-28T00:52:45.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15157" PostTypeId="2" ParentId="15087" CreationDate="2015-05-28T02:33:31.953" Score="1" Body="&lt;p&gt;Another factor:  Consistency.  Pilots might have to land on something other than their home carrier.  Carrier landings are already very exacting flying, learning one pattern is better than learning two.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-05-28T02:33:31.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15158" PostTypeId="1" CreationDate="2015-05-28T03:17:21.887" Score="0" ViewCount="1242" Body="&lt;p&gt;The suites offered by many airlines for the super rich, are very spacious and convenient. Though, I can only &lt;a href=&quot;http://m.businessinsider.in/10-First-Class-Airplane-Seats-That-Are-Nicer-Than-Your-Apartment/articleshow/35034905.cms&quot; rel=&quot;nofollow&quot;&gt;Read&lt;/a&gt; about them! One thing I can see is, the A380 is capable of upto 853 economy only passengers, but most of them carry 500 economy, 65 business and 12 suites. So, they must be eating some considerable amount of space. What I am asking is, basically the number of economy class seats that would fit inside a first class cabin and not how much space is available for first class and economy class cabins.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-05-28T06:43:35.287" LastActivityDate="2015-05-28T06:43:35.287" Title="On an average, space of how many economy class seats is taken up by a suite?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-05-28T15:09:36.567" ContentLicense="CC BY-SA 3.0" />
  <row Id="15159" PostTypeId="2" ParentId="15158" CreationDate="2015-05-28T05:35:33.720" Score="3" Body="&lt;p&gt;The size of the seat is slightly different in each airline, but according to &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380_seat_configurations&quot; rel=&quot;nofollow&quot;&gt;this table&lt;/a&gt;, 32&quot;×18&quot; is the smallest, and most common, economy seat. That is 4 ft².&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the article you linked, the largest suite is 125 ft². That is 31¼ times more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, however, that space is not the only consideration. The main consideration for aircraft is &lt;em&gt;weight&lt;/em&gt; and obviously first class passenger does not weigh more than economy class one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider that those 853 passengers, with baggage, will weight around 80 t. Maximum take-off weight is 575 t of which 276 t is empty weight and the tanks can take about 260 t of fuel. But that leaves you only 39 t for payload with full tanks! So on very long routes, the aircraft &lt;em&gt;can't&lt;/em&gt; pack 853 passengers anyway. The 500 is about maximum that makes sense (for long range variant, which is most common).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So they don't mind wasting some space for luxurious first class if they can charge premium for it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-05-28T05:58:45.577" LastActivityDate="2015-05-28T05:58:45.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15160" PostTypeId="2" ParentId="12458" CreationDate="2015-05-28T07:46:53.497" Score="1" Body="&lt;h2&gt;More (likely) ways to Die&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I'm going to add another twist: &lt;strong&gt;There are more ways to die in a plane than in a plane crash&lt;/strong&gt;, which your question implies. Business class is spacious, comfortable and relaxing. Economy class is loud, tight and uncomfortable.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If your movement is restricted, you could get Deep Vain Thrombosis. More a risk in economy than spacious business class where you have the space and comfort to move.&lt;/li&gt;&#xA;&lt;li&gt;You are sitting closer to a load of other passengers who could in theory give you some flu or something in economy than business.&lt;/li&gt;&#xA;&lt;li&gt;You are treated like livestock in economy and correspondingly more stressfully. It wouldn't surprise me if you're more likely to get a heart attack for that reason than you ever are to die in a plane crash.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In my humble opinion: If you're sufficiently concern to be reading this, book a seat in business: relax in the lounge before the flight, sit with fewer passengers, have the flight attendants close at hand if you have questions or concerns and enjoy some good food.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Dataset Limiations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Your data is limited in that it does not go into the &lt;strong&gt;change of risk depending on the conditions in which you are flying&lt;/strong&gt;. If you're flying over water, there is the ever-so-marginal risk the plane might ditch. You are then better off in the front, since it normally doesn't strike the water and floats nose-up. There are unpleasant stories from US1549 (Hudson Crash) about the rear of the plane, whereas the evacuation at front was relatively clam. Depending on the specific destination, you might be better off in another section of the plane. This is the reason why there is no clear trend and just about every authority including Boeing and the FAA says that every seat is as good as any other seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, your data is based upon accidents dating all the way back from 1971. This is not really a representation of the current risk since the causes of accidents have changed. For instance, Ground Proximity Warning Systems (to stop you flying into mountains) was made mandatory for Part 121 and Part 135 operators only in 1978. Incidentally, the types of accidents this applies to involves going into terrain nose-first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is that probability is so incredibly remote it is virtually impossible to put halfway reliable number to stuff like this. Unlike vehicle traffic, the fatality rate jumps substantially depending on how many accidents just happen to occur that year.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-28T09:09:45.870" LastActivityDate="2015-05-28T09:09:45.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15161" PostTypeId="2" ParentId="9243" CreationDate="2015-05-28T07:53:25.800" Score="-1" Body="&lt;p&gt;An airliner travelling at over 800 kmph could never have a chute safely deploy in mid air... the design of such a thing wouldn't be possible. The strings, however synthetic, whether carbon fiber or whatever else would never hold to such pressure. Furthermore, the jolting force of have a chute deploy even at the minimum required flight speed of your average commercial jet, let's say 250mph would jolt passengers to the point of serious injury. &lt;/p&gt;&#xA;" OwnerUserId="8662" LastActivityDate="2015-05-28T07:53:25.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15163" PostTypeId="1" CreationDate="2015-05-28T10:13:10.507" Score="12" ViewCount="5477" Body="&lt;p&gt;This is for an electric airplane (so no fuels for combustion):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Are propellers the only option? &lt;/li&gt;&#xA;&lt;li&gt;Is there a turbine-jet possible with only air intake, electrically compress, and  a turbine and nozzle and get equal or more thrust than a propeller like a water-jet but then with air?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8664" LastEditorUserId="19" LastEditDate="2016-07-14T08:11:21.783" LastActivityDate="2019-04-30T20:29:33.410" Title="For an electric airplane are propellers the only option for propulsion?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;turbine&gt;&lt;electric-engine&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15164" PostTypeId="2" ParentId="15163" CreationDate="2015-05-28T10:30:32.487" Score="15" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Propellers in some form are really the only option. It is currently the only efficient way to generate thrust with air as a medium. Even jet engines are in some sense just a very elaborate system of propellers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The reason for the turbine is to create an environment to efficiently burn fuel (&lt;em&gt;suck, squeeze, bang, blow&lt;/em&gt;) to generate as much thrust as possible. Hence, in an electric aircraft this is irrelevant. You might be interested in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_E-Fan&quot; rel=&quot;nofollow&quot;&gt;Airbus E-Fan&lt;/a&gt;, which uses ducted propellers increase efficiency. However, it is still 'just' a propeller with an electric motor in the middle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-29T00:57:23.533" LastActivityDate="2015-05-29T00:57:23.533" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15165" PostTypeId="1" CreationDate="2015-05-28T10:46:38.077" Score="14" ViewCount="730" Body="&lt;p&gt;&lt;em&gt;Comment: I know this doesn't represent reality, it is a hypothetical scenario.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have the impression safety measures are non-linear in cost, i.e. that reducing the accident rate by one percent costs more than the preceding percent. We often go to great lengths (and costs) to eliminate very unlikely events from happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Let's just assume that we would tolerate the fatality rate of aircraft to be 10 times as high as it currently is&lt;/strong&gt;. Flying would be even more  attractive and cheaper than going by car (replacing cars on more distances) and would still be statistically safer, so there would still be less fatalities overall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an estimate on how much the ticket price for end passenger could decrease if we allowed for this to happen? The usage case would be the average commercial aircraft on for instance a 2-3 hour short haul flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reduce number and frequency of maintenance checks.&lt;/li&gt;&#xA;&lt;li&gt;Dispatch aircraft to their destinations under less stringent Minimum Equipment Lists.&lt;/li&gt;&#xA;&lt;li&gt;Have lower pilot requirements.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-30T01:01:20.460" LastActivityDate="2015-06-02T07:26:10.357" Title="How much cheaper would flying be if we made it less safe?" Tags="&lt;safety&gt;&lt;cost&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15166" PostTypeId="1" AcceptedAnswerId="15167" CreationDate="2015-05-28T12:11:28.780" Score="8" ViewCount="2440" Body="&lt;p&gt;I am wondering that if missiles fired from jet fighters can ascend or descend?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they going to aim only horizontally?&lt;/p&gt;&#xA;" OwnerUserId="7115" LastEditorUserId="1696" LastEditDate="2018-04-23T17:07:46.943" LastActivityDate="2018-04-23T20:20:46.047" Title="Can jet fighter missiles descend or ascend?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;missiles&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15167" PostTypeId="2" ParentId="15166" CreationDate="2015-05-28T12:27:25.737" Score="15" Body="&lt;p&gt;Yes, they can. Air-to-Air or Air-to-Ground missiles are often equipped with little fins that allow certain maneuverability or also with &lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_vectoring&quot;&gt;thrust vectoring&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jXBMy.jpg&quot; alt=&quot;AIM9 Sidewinder&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://de.wikipedia.org/wiki/AIM-9_Sidewinder#/media/File:Aim_9.jpg&quot;&gt;WikiPedia&lt;/a&gt; - Author: USAF)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dDXSo.png&quot; alt=&quot;Thrust Vectoring&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/En_Gimbaled_thrust_diagram.svg/621px-En_Gimbaled_thrust_diagram.svg.png&quot;&gt;WikiPedia&lt;/a&gt; - Author: Titimaster)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-05-28T12:27:25.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15168" PostTypeId="2" ParentId="15166" CreationDate="2015-05-28T12:38:27.353" Score="7" Body="&lt;p&gt;Long range missiles benefit from the lower air density at higher altitudes. Short-range missiles normally fly line-of-sight to the target, but for distances of more than 8 or 10 km, the range of the missile increases significantly if it first climbs for the cruise phase, and only descends when it closes in on the target.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-05-28T12:38:27.353" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15169" PostTypeId="2" ParentId="15163" CreationDate="2015-05-28T12:59:21.370" Score="4" Body="&lt;p&gt;You do not have hot combustion gases in an electrically powered engine. The only gas available to you is the air around you, and some form of propeller is the most logical way to accelerate that air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nozzle you're imagining can be used to turn a large, slow stream of air into a faster but smaller air stream. This can't provide thrust by itself as it isn't a powered engine part.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-05-28T12:59:21.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15170" PostTypeId="1" CreationDate="2015-05-28T13:10:16.137" Score="1" ViewCount="123" Body="&lt;p&gt;A follow up on &lt;a href=&quot;https://aviation.stackexchange.com/questions/15147/why-airplane-captain-sits-on-left-seat&quot;&gt;this question&lt;/a&gt;, one answer mentioned that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/15148/2265&quot;&gt;Please note that on many helicopters, captains sit on the right side.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why is that?&lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-05-28T13:10:16.137" Title="Why do most helicopter pilots sit on the right?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;aviation-history&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-05-28T13:42:17.850" ContentLicense="CC BY-SA 3.0" />
  <row Id="15171" PostTypeId="2" ParentId="15163" CreationDate="2015-05-28T13:15:53.987" Score="8" Body="&lt;p&gt;You may choose whatever propulsion you prefer, but need to accept the consequences. An electrical turbine is easy to build, but will need a lot of power for heating the core flow. Instead of burners you will need to install heater elements, which will necessitate a longer flow path and more volume between compressor and turbine, but by and large the electric turbine engine will look much like a fuel-burning one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also remove all the turbo machinery and only drive the fan with a big electric motor. But that would have &lt;a href=&quot;https://aviation.stackexchange.com/questions/9940/what-are-the-advantages-and-disadvantages-of-ducted-fans-in-designs-such-as-the/9949#9949&quot;&gt;lower efficiency&lt;/a&gt; than turning a propeller instead, so only when your flight speed will cause supersonic propeller tips might an electrically powered fan be a better alternative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, at speeds below Mach 0.7 propellers will give you more thrust per kW of power, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/why-are-radial-engines-uncommon-on-commercial-aircraft/10037#10037&quot;&gt;their efficiency is best at low speeds&lt;/a&gt;. The much lower energy density of electric storage will demand flight at low speed, or your flight time will be very short. Therefore, propellers are the best, but by no means the only solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A potentially even more efficient method might be &lt;a href=&quot;http://news.mit.edu/2013/ionic-thrusters-0403&quot; rel=&quot;nofollow noreferrer&quot;&gt;ionic thrusters&lt;/a&gt; where a high voltage is used to ionize and accelerate air in order to produce thrust. Designs using ionic thrusters would use the whole airframe for thrust creation and would need to be run at tens of thousands of Volts, but their potential efficiency surpasses even that of low-speed propellers - in theory. The linked article, however, is an embarrassment to MIT. A 1 kW jet engine that produces only 2 N thrust has to fly very fast (500 m/s, to be precise) while the 110 N cited for the ionic thruster at the same power mean that it could not had moved faster than 9 m/s.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-04-30T20:29:33.410" LastActivityDate="2019-04-30T20:29:33.410" CommentCount="15" ContentLicense="CC BY-SA 4.0" />
  <row Id="15172" PostTypeId="2" ParentId="15163" CreationDate="2015-05-28T14:13:41.820" Score="4" Body="&lt;p&gt;Ducted fans rather than external propellers increase the performance at high speeds, so gets round most of the problems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You aren't really going to want to carry fuel AND batteries, so some sort of ducted fan is the best solution for a high speed aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While they do look somewhat like Jet engines, they are basically just prop engines in a tube, so they can better control the air-flow, which at high velocities, can cause issues for exposed props. &lt;/p&gt;&#xA;" OwnerUserId="8669" LastActivityDate="2015-05-28T14:13:41.820" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15173" PostTypeId="2" ParentId="15165" CreationDate="2015-05-28T14:25:31.920" Score="6" Body="&lt;p&gt;Lets completely remove liability from the picture. The airlines are simply not responsible for anything that happens to the passengers, and as a result they don't care. Seatbelts, oxygen systems, escape slides - who needs them? Flight recorder? In the trash. FAA staff are cut to 20% of current levels and are mainly concerned with keeping things running smoothly (their pay is docked across the board when flights are late) and the NTSB is defunded. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Daily operating costs go down a bit. We've removed a couple of hundred kilograms of safety equipment and that will make a small dent in the fuel bill. But only a small one. The mini-Starbucks installed where the over-wing exits used to be weighs about the same. Costs related to FAA-mandated paperwork are eliminated, but only temporarily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's less training for the cabin crew, but we can replace the evacuation training with sales training to bump up profits from regular and duty-free sales. Hooters re-enters the air carrier industry and does quite well, as cabin crew can be transferred directly from the restaurants skipping all that troublesome FAA qualification business.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But we find that maintenance costs don't go down. Costs plummet for the first year, but then go back up as management realizes that an airplane on the ground because it won't start costs a lot more in losses than maintaining it properly to begin with. And the one that crashed on takeoff was a complete loss on the airframe ($100mil and up) along with a dent in sales for the following 6 months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight recorders are reinstalled as they are actually rather useful to predict if something is going to break. It can then be replaced by the night shift. The FAA paperwork we stopped doing is also quite useful for deciding wether or not to overhaul the wheel bearings with winter-weight grease, as we wrote down when it was last done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flying public will see maybe 10% reduction in fares. Remember that a very large percentage of ticket costs are taxes. For example, flying out of the UK costs up to £194 just for taxes. Wether the public will accept a large decrease in oversight for a small decrease in fares, or wether the long-term accident rate actually goes up or down will be a very interesting social experiment.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-05-28T14:25:31.920" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15174" PostTypeId="2" ParentId="15165" CreationDate="2015-05-28T14:33:33.097" Score="2" Body="&lt;p&gt;This is a very broad question that covers many factors and may be hard to pinpoint just how much the prices could drop but lets look at a few factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Insurance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The minimum you would need is collateral against the plane falling out of the sky and hitting something but if you chose to have passengers sign some kind of a waiver you may be able to get away with not insuring the plane/passengers which would drop the costs. I dont have the specific numbers on how much these things cost so I wont comment on just how much it will drop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Maintenance&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are overhauled frequently to check for issues and insure that there are no failing components. However some people have long thought that overhauling on time intervals may not really matter. There is an interesting &lt;a href=&quot;http://blog.aopa.org/opinionleaders/2014/03/13/do-tbos-make-sense/&quot; rel=&quot;nofollow&quot;&gt;article here&lt;/a&gt; about overhauling piston engines and many owners of small planes have made it past TBO issue free. If you extended maintenance intervals you could cut cost but you may also see things break more frequently. In some cases its cheaper to replace it before it breaks than after it breaks and takes a lot of other pieces with it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Training&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you cut back on crew training you could hire less experienced people you could arguably pay them less. Again you may see more accidents and thus have to end up paying more out in the end. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth you are better off with a constantly running, well maintained fleet than a broken, rickety fleet. You could always opt for &lt;a href=&quot;http://business.time.com/2012/11/12/new-low-for-flying-standing-room-only/&quot; rel=&quot;nofollow&quot;&gt;standing room only flights&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-05-28T14:33:33.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15176" PostTypeId="1" AcceptedAnswerId="15177" CreationDate="2015-05-28T17:22:33.733" Score="5" ViewCount="1062" Body="&lt;p&gt;I had an event in 2005 that has not happened in the 10 years since.  When I went for a 3rd class medical the AME I went to seemed very skittish and wanted to send my records to Oklahoma City for review.  They received them the first week in March.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As we near the two month mark I have called and asked for a status once each week and have been struck by how little information they provide.  My application, for example, has been in the &quot;handed over to the Doctors&quot; status for almost a month with no new notations on the file.  This means I can't tell if it is sitting in the queue waiting to be processed, or is actually being processed by a Doctor who just isn't putting any notations in.  If I'm in the queue I have no way of knowing whether there are two or two hundred apps in front of mine.  In short, calling and checking the status is a worthless exercise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In every organization I've ever dealt with there was always some way of going up the chain and getting some kind of information.  I'm told by the call center reps that is not possible.  I wanted to verify that information with the community here, though... is this just the way things are?  Is there no way whatsoever to get some useful information?  If anyone has been down this road and has tips they would be greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="688" LastEditDate="2015-05-28T17:53:19.163" LastActivityDate="2015-05-29T14:02:10.880" Title="Is there truly no way to get information about medical application status?" Tags="&lt;medical&gt;&lt;faa-approval&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15177" PostTypeId="2" ParentId="15176" CreationDate="2015-05-28T21:36:34.867" Score="4" Body="&lt;p&gt;Dealing with the FAA medical is always a tiring process. Best places to consult would be services like AOPA medical assistance, or through &lt;a href=&quot;https://www.aviationmedicine.com/&quot; rel=&quot;nofollow&quot;&gt;Aviation Medical Advisory Service (AMAS)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other options probably, but I know AMAS is the go to consulting group for controllers and a lot of airline pilots. AMAS will often help guide you with knowing ahead of time what information you need and what forms to have filled out to try and make the process go quickly.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="65" LastEditDate="2015-05-29T14:02:10.880" LastActivityDate="2015-05-29T14:02:10.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15178" PostTypeId="2" ParentId="2549" CreationDate="2015-05-28T21:40:14.720" Score="-1" Body="&lt;p&gt;Both the winds and earth's rotation affect the difficulty of flight eastbound vs. westbound.  If eastbound is slower and harder and winds carry you &lt;strong&gt;&lt;em&gt;westbound&lt;/em&gt;&lt;/strong&gt;, I take it you're within the &lt;strong&gt;tropics&lt;/strong&gt;, where the tradewinds govern flight direction.  Kentucky and Utah, and farther north latitude (and likewise south to Argentina) the winds work in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The poles and equator differ in (eastward) rotation speed.  The equator has farther to go and keeps up with the axis by going faster.  So land nearer the axis (Canada, Argentina) takes it slow spinning east, &lt;strong&gt;slower&lt;/strong&gt; than wind and weather.  So that's where to take advantage of the winds &lt;strong&gt;&lt;em&gt;eastbound&lt;/em&gt;&lt;/strong&gt;.  The tradewinds are at the equator, where the ground follows (east) a bigger circle, &lt;strong&gt;faster&lt;/strong&gt; than wind and weather.  There, the &lt;strong&gt;&lt;em&gt;westbound&lt;/em&gt;&lt;/strong&gt; is more efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about Alabama/Arizona/etc, but I wager the eastbound and westbound are about the same, since they are in-between the north and tropics (and Bolivia the in-between of the southern hemisphere).  The latitude makes quite a difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike planes being pushed by wind, space shuttles leave the atmosphere.  Being propelled only by earth's rotation, &lt;strong&gt;all rockets go east&lt;/strong&gt; no matter the latitude.&lt;/p&gt;&#xA;" OwnerUserId="8675" LastEditorUserId="1696" LastEditDate="2015-05-28T21:57:04.190" LastActivityDate="2015-05-28T21:57:04.190" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15180" PostTypeId="1" CreationDate="2015-05-28T23:14:24.430" Score="11" ViewCount="4375" Body="&lt;p&gt;When one views a center of gravity limit chart, in this case a C-182T chart, one notices that the forward C.G. line has two small bends in it, one around 2250# mark and the other around the 2675# mark. Why the two bends in the forward C.G. limit line? What has happened at these two points?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZWtdE.png&quot; alt=&quot;Center-of-gravity limits for Cessna 182T&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from: &lt;a href=&quot;http://axenty.com/resources/PIM/C182T%20PIM%20%28NAV%20III%29.pdf&quot; rel=&quot;noreferrer&quot;&gt;C-182T POH&lt;/a&gt; pg. 211&lt;/p&gt;&#xA;" OwnerUserId="8673" LastEditorUserId="1696" LastEditDate="2015-05-29T14:36:06.837" LastActivityDate="2019-05-09T11:34:10.660" Title="How are the limits of the center of gravity chart established?" Tags="&lt;weight-and-balance&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15181" PostTypeId="1" AcceptedAnswerId="15182" CreationDate="2015-05-29T02:54:33.693" Score="10" ViewCount="2207" Body="&lt;p&gt;I've attempted to fly formation over a multiplayer flight simulator, and it was incredibly hard. It felt really hard to have the two planes go exactly the same heading, so it was always necessary to sway the yoke back and forth, constantly overshooting and undershooting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When real planes fly formation, do they use some sort of short-range radar system and an autopilot to maintain the formation shape? I could imagine that manually flying formation would cause extreme fatigue due to the need to constantly fiddle with trim and yoke, and would be very dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is this simply a case of actual pilots having actual training, instead of my amateur &quot;training&quot; of fiddling around in the simulator overusing instruments?&lt;/p&gt;&#xA;" OwnerUserId="8357" LastEditorUserId="3386" LastEditDate="2015-05-29T16:24:21.917" LastActivityDate="2015-06-12T06:20:59.193" Title="Do planes use autopilot when flying in formation?" Tags="&lt;autopilot&gt;&lt;flying-in-formation&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15182" PostTypeId="2" ParentId="15181" CreationDate="2015-05-29T06:10:54.533" Score="12" Body="&lt;p&gt;Nope, pilots do not use autopilot to fly in formation. An autopilot cannot achieve the precision required for flying formation (e.g. keep the wingtip aligned to that door). Usage of autopilot would also hinder responses when an immediate correction is necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may refer to the TV episode Jet Stream and Blue Angle training videos on the internet. From the pilot's perspective, the planes are always moving around, though in a confined space. Continuous small adjustment is necessary. From the ground, the small floating cannot be noticed visually because the observer is too far away.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;P.S. Based on my 17 years of experience with PC flight simulator, flying in formation in multiplayer is definitely doable, and can become second nature with practice.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-05-29T10:22:17.733" LastActivityDate="2015-05-29T10:22:17.733" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15183" PostTypeId="1" AcceptedAnswerId="15187" CreationDate="2015-05-29T07:10:41.503" Score="13" ViewCount="3267" Body="&lt;p&gt;I fly regularly KLM 573 from Amsterdam to Dar es Salaam. This flight does a stop over in Kilimanjaro International Airport and no passengers are boarded, but passengers are disembarked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also other flights of other airlines that I know of that do this (Turkish airlines, Swiss International).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this done? Wouldn't it be more of an advantage to pick up some more passengers in a short intermediate flight in order to maximize profits?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or does the hassle of loading/unloading luggage and passengers make it less viable?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2016-07-14T08:09:25.267" LastActivityDate="2016-08-20T04:25:39.233" Title="Why do airlines have intermediate stopovers with no passenger boarding?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15184" PostTypeId="2" ParentId="15183" CreationDate="2015-05-29T07:27:20.627" Score="12" Body="&lt;p&gt;Very few countries allow foreign operators to provide transport services between destinations within the country. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since both Kilimanjaro International and Dar es Salaam are in Tanzania, the government will simply not allow KLM to take additional passengers on this flight. Otherwise it would be strong competition for their local transportation companies. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The official word for this is &quot;cabotage&quot;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Cabotage&lt;/strong&gt; is the transport of goods or passengers between two points in the same country by a vessel or an aircraft registered in another country&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Freedoms_of_the_air#Cabotage&quot; rel=&quot;nofollow&quot;&gt;(Wikipedia)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually these rights are agreed upon in bilateral agreements between countries. Within the EU member states cabotage is allowed and heavily used (e.g. Ryanair) but outside the EU cabotage is rare. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Actually the flight you mention, KL573, is a direct AMS-DAR flight and does not stop in Kilimanjaro (JRO).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another KLM flight, KL569, does stop in JRO on its way to DAR. It flies the AMS-JRO-DAR-AMS route. You can book this flight from AMS to JRO or from AMS to DAR, but also from JRO to AMS (via DAR) or DAR to AMS. You cannot book the JRO to DAR leg without the continuing leg to Amsterdam.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there should be people boarding in JRO when you are on your way to DAR. These people will not get off in DAR though, they will continue to AMS. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="938" LastEditDate="2016-08-20T04:25:39.233" LastActivityDate="2016-08-20T04:25:39.233" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15185" PostTypeId="2" ParentId="15180" CreationDate="2015-05-29T08:41:54.460" Score="14" Body="&lt;p&gt;These &quot;bends&quot; (or sloped straight lines) are due to various structural constrains on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2mUfu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In level flight, the sum of forces must be zero:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift&lt;sub&gt;Wing&lt;/sub&gt; - Weight - Lift&lt;sub&gt;Tail&lt;/sub&gt; = 0&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The summation of moment should also be zero, otherwise the plane will pitch up or down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing has a structural limitation, i.e. a maximum loading. Solving the above equations for constant Lift&lt;sub&gt;Wing&lt;/sub&gt; yields a slopped straight line. &lt;strong&gt;This is the &quot;bend&quot; portion you see in the graph.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drawing these lines (shown as colored lines here) on top of a weight and balance graph yields:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Mml9U.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The resulted graph is the &lt;strong&gt;intersection&lt;/strong&gt; of the various constraints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the C-182 graph, there are five constraints (five edges). Wing loading and tail loading is used as an example here, since I do not know what is the actual constraint used by the engineers. Another possibility is strength of the nose gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Main landing gear loading and aft tipping limit would have resulted in a downward slope, which does not correspond to the given graph.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=Center_Of_Gravity_Limitations.pdf&quot; rel=&quot;noreferrer&quot;&gt;Center of Gravity Limitations (PDF)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-05-29T13:57:55.613" LastActivityDate="2015-05-29T13:57:55.613" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15186" PostTypeId="2" ParentId="15163" CreationDate="2015-05-29T09:25:50.620" Score="0" Body="&lt;p&gt;The main difference between air and water is that the second cannot be compressed, while the first can and when you do, you heat it up loosing a cospicuous amount of energy. The more you compress it and the more time you wait before releasing it, the more energy you loose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A propeller also compresses the air: this is necessary to accelerate it, but it allows to achieve high air velocities with the minimum amount of compression. It is also a very simple and light design, moreover one of the motivation to have an internal water compressor is the possibility to filter it, which is not required with air.&lt;/p&gt;&#xA;" OwnerUserId="2345" LastActivityDate="2015-05-29T09:25:50.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15187" PostTypeId="2" ParentId="15183" CreationDate="2015-05-29T09:46:09.167" Score="14" Body="&lt;p&gt;DeltaLima is correct but there is a little more to the story which he hints at in his link. This topic is known as &lt;em&gt;Freedoms of the Air&lt;/em&gt;. There are five official in total, each dictating in what way an airline may operate in a foreign country. What KLM has done is a:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Normal stop for those getting off.&lt;/li&gt;&#xA;&lt;li&gt;Technical stop for the onward passengers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Both are less controversial than what would essentially be letting a foreign operator offer flights in your country, which would not help local carriers ( and which would constitute Cabotage as DeltaLima says).&lt;/p&gt;&#xA;&lt;p&gt;The technical stop is defined in the second freedom of the air:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Second Freedom of the Air&lt;/strong&gt; - the right or privilege, in respect of scheduled international air services, granted by one State to another State or States to land in its territory for non-traffic purposes (also known as a Second Freedom Right).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The Third and Fourth Freedom states that the airline can load and unload passengers in a foreign country for transport to and from the carrier home country:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Third Freedom of The Air&lt;/strong&gt; - the right or privilege, in respect of scheduled international air services, granted by one State to another State to put down, in the territory of the first State, traffic coming from the home State of the carrier (also known as a Third Freedom Right).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Fourth Freedom of The Air&lt;/strong&gt; - the right or privilege, in respect of scheduled international air services, granted by one State to another State to take on, in the territory of the first State, traffic destined for the home State of the carrier (also known as a Fourth Freedom Right).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(Needless to say, 3 and 4 go hand-in-hand)&lt;/p&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.icao.int/Pages/freedomsAir.aspx&quot; rel=&quot;noreferrer&quot;&gt;ICAO&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;See also this &lt;a href=&quot;http://www.boeing.com/resources/boeingdotcom/company/about_bca/pdf/StartupBoeing_Freedoms_of_the_Air.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boeing document&lt;/a&gt; for easier reading.&lt;/p&gt;&#xA;&lt;p&gt;The other option, aside from not doing it for legal reasons, is that KLM cannot justify the trouble and cost of doing it.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Setting up more domestic presence (websites, additional staff, pricing in regard to competition) in a foreign country is a somewhat complicated business.&lt;/li&gt;&#xA;&lt;li&gt;There would be additional waiting time on the ground when stuff was loaded and paperwork sorted out.&lt;/li&gt;&#xA;&lt;li&gt;Furthermore, I imagine that KLM would like to block the free seats for the complete leg as long as possible (which would generate the greatest revenue), so the actual number of available sub-segments for booking would not be that great.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-29T11:08:29.750" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15188" PostTypeId="1" AcceptedAnswerId="15193" CreationDate="2015-05-29T10:12:42.697" Score="12" ViewCount="2134" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/V_formation&quot; rel=&quot;nofollow&quot;&gt;V Flight Formation&lt;/a&gt;has been found to be helpful in achieving greater fuel efficiency and range. Though it is currently used mostly for military purposes, what restricts it from being used for commercial purposes?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-14T04:32:36.660" LastActivityDate="2015-08-14T17:24:14.490" Title="Why isn't the V flight formation being used for commercial purposes?" Tags="&lt;aerodynamics&gt;&lt;commercial-aviation&gt;&lt;flying-in-formation&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15189" PostTypeId="2" ParentId="15188" CreationDate="2015-05-29T10:23:30.033" Score="11" Body="&lt;p&gt;Formation flight is not allowed by the FAA when carrying paying passengers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&quot;&gt;14 CFR 91&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.111   Operating near other aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may operate an aircraft so close to another aircraft as&#xA;  to create a collision hazard.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may operate an aircraft in formation flight except by&#xA;  arrangement with the pilot in command of each aircraft in the&#xA;  formation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No person may operate an aircraft, &lt;strong&gt;carrying passengers for hire&lt;/strong&gt;,&#xA;  in formation flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The core reason would be safety. If any craft has a problem it needs to be able to get out of formation safely and pilots need to be trained for it. Also flying at cruise requires the autopilot; however no current civilian autopilot can make adjustments to account for maintaining separation in formation flight.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-05-29T10:23:30.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15190" PostTypeId="1" AcceptedAnswerId="15197" CreationDate="2015-05-29T11:12:57.567" Score="2" ViewCount="2695" Body="&lt;p&gt;I am MSC student of mechanical engineering and my project is about ACM machine. I have read something about various systems of air conditioning system in aircrafts;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;simple system&lt;/li&gt;&#xA;&lt;li&gt;boot strap&lt;/li&gt;&#xA;&lt;li&gt;reduced ambient temperature&lt;/li&gt;&#xA;&lt;li&gt;regenerative system&lt;/li&gt;&#xA;&lt;li&gt;boot strap with evaporator&lt;/li&gt;&#xA;&lt;li&gt;simple system with evaporator&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I just know that reduced ambient temperature is for supersonic aircraft.I don't know other systems applications.For example, when is a regenerative system used and when boot strap is used?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are all of the possible air conditioning systems exists in every aircraft and switch to another depending on flight condition?&lt;/p&gt;&#xA;" OwnerUserId="8668" LastEditorUserId="1696" LastEditDate="2015-05-29T14:31:07.740" LastActivityDate="2015-05-29T14:31:07.740" Title="What are the differences between these types of air cycle machines?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15191" PostTypeId="1" AcceptedAnswerId="15192" CreationDate="2015-05-29T12:21:49.947" Score="5" ViewCount="484" Body="&lt;p&gt;The requirements for military and civil aircraft are pretty different, so this possibly applies to their autopilots. Are they different in the way they function or capabilities that they are programmed with?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="572" LastEditDate="2015-05-29T12:25:29.273" LastActivityDate="2015-05-30T02:38:59.790" Title="How much different are civilian and military aircraft autopilots?" Tags="&lt;autopilot&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15192" PostTypeId="2" ParentId="15191" CreationDate="2015-05-29T13:18:01.637" Score="7" Body="&lt;p&gt;There is no civillian autopilot for an F-16, because there are no non-military F-16s. Ditto with the F-117 or or B-1 or B-2, so who knows what unique modes those autopilots have for their uniquely military missions (i.e. dropping bombs or low level terrain following). However, when the military aircraft has a non-military equivalent (KC-10/DC-10, KC-135/B707, C-40/T-43/B737, C-21/Learjet, T-44/C-12/KingAir, etc) then the autopilots are generally identical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any differences are more likely to be found in FMC software rather than in the Autopilot, and those differences would be very specific to each aircraft &amp;amp; its mission.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-05-29T13:18:01.637" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15193" PostTypeId="2" ParentId="15188" CreationDate="2015-05-29T13:19:12.543" Score="14" Body="&lt;p&gt;This possibility has actually been studied and discussed (e.g. &lt;a href=&quot;http://news.stanford.edu/news/2009/june3/birds-060309.html&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://www.extremetech.com/extreme/135774-air-travel-in-2050-autonomous-planes-flying-in-geese-like-formations&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://www.ibtimes.co.uk/future-aircraft-will-fly-formation-like-flocks-birds-hypersonic-speeds-1483961&quot;&gt;here&lt;/a&gt;) as a way to save fuel costs, but there are several issues with implementing it today:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You need to schedule a number of aircraft all flying the same route at the same time for a significant amount of time&lt;/li&gt;&#xA;&lt;li&gt;If different, competing airlines should participate in one formation then they have to cooperate and be satisfied that no one is at a commercial (dis)advantage&lt;/li&gt;&#xA;&lt;li&gt;A lot of work would need to be done on procedures and training (how does the formation form up, who takes the lead, how/when does the formation leader change, how are emergencies handled, what flight levels are used, what separation is required between formation and non-formation flights etc.)&lt;/li&gt;&#xA;&lt;li&gt;Autopilots, software and other equipment would need major updates, which in turn requires re-certification&lt;/li&gt;&#xA;&lt;li&gt;All relevant regulations on separation, formation flying and so on would need to be reviewed and changed which in most countries means changing the aviation laws, and changing any law is usually a long, slow process&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Having said all that, you'll notice that most of those issues are procedural, not technical. In theory it's a viable approach, but turning that theory into reality would require a lot of work.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-05-29T13:19:12.543" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15194" PostTypeId="1" AcceptedAnswerId="15196" CreationDate="2015-05-29T13:34:24.567" Score="14" ViewCount="3415" Body="&lt;p&gt;I am trying to find more information on &quot;true&quot; vs. &quot;indicated&quot; Mach number (not airspeed). I've found older fighter aircraft manuals online that have a conversion chart from one to the other, but the modern jets I've flown don't have such charts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a recent flight at 41000 feet, at a Mach number of 0.81, a true airspeed of 476 knots was displayed on the EFIS. In the standard atmosphere, 81% of the speed of sound is 464 knots at that altitude. Sure enough, the actual temperature was some 13 degrees C warmer than the &quot;standard&quot; -56.5 C, hence the true airspeed of 476 knots instead of 464. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that leads me to believe that the Mach number I am flying is not really &quot;true&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The relevant flight manuals do not use the words &quot;indicated&quot; or &quot;true&quot; to qualify the Mach number.&lt;/p&gt;&#xA;" OwnerUserId="8681" LastActivityDate="2019-10-19T17:36:17.477" Title="Is the Mach number shown by an Air Data Computer considered a &quot;true&quot; Mach number?" Tags="&lt;airspeed&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15195" PostTypeId="2" ParentId="15194" CreationDate="2015-05-29T13:58:33.803" Score="7" Body="&lt;p&gt;Mach is a number in relation to the speed of sound. The speed of sound is &lt;strong&gt;solely dependent on the outside air temperature&lt;/strong&gt;. Hence unlike airspeed there is no such thing as 'indicated' mach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ M=\frac{TAS}{a}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ a= \sqrt{1.4*288.15*T}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $a$ is the speed in m/s of sound and $T$ is the temperature in Kelvin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The old jets needed conversion charts since the true airspeed was not computed by computer and &lt;a href=&quot;https://en.wikipedia.org/wiki/Machmeter&quot; rel=&quot;noreferrer&quot;&gt;machmeters&lt;/a&gt; used a best estimate value limited by the error in pressure. The following is from a &lt;a href=&quot;http://www.scribd.com/doc/19204672/USAF-Flight-Test-Engineering-Handbook&quot; rel=&quot;noreferrer&quot;&gt;USAF handbook&lt;/a&gt; on how the Machmeter works:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nkQMm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eGTyG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/2263.pdf&quot; rel=&quot;noreferrer&quot;&gt;document&lt;/a&gt; by Airbus also suggests you are looking the ratio of True Airspeed.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-29T14:25:37.097" LastActivityDate="2015-05-29T14:25:37.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15196" PostTypeId="2" ParentId="15194" CreationDate="2015-05-29T14:19:58.977" Score="13" Body="&lt;p&gt;For subsonic aircraft the Mach number is normally measured from dynamic pressure and static pressure, very similar to the way calibrated airspeed is measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$M_a=\sqrt{\frac{2}{\gamma-1}\left[\left(\frac{q_c}{p}+1\right)^\frac{\gamma-1}{\gamma}-1\right]} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$M_a$, the Mach number&lt;/li&gt;&#xA;&lt;li&gt;$q_c$, the dynamic pressure&lt;/li&gt;&#xA;&lt;li&gt;$p$, the static pressure&lt;/li&gt;&#xA;&lt;li&gt;$\gamma$,  the ratio of specific heats (1.4) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If there is an error in the measurement of either the dynamic or the static pressure both the indicated airspeed and Mach number will be affected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the Mach number has no direct dependency on temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The true airspeed is calculated by the ADC from the Mach number and the outside air temperature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_{TAS} = M_a \cdot \sqrt{\gamma R T_S}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$R$, the specific gas constant (287.05 for dry air)&lt;/li&gt;&#xA;&lt;li&gt;$T_S$, the static air temperature&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The indicated true airspeed has a direct dependency on the static air temperature ($T_S$,SAT) also known as the outside air temperature (OAT). The static temperature cannot be measured directly since the air will heat up on impact with the temperature sensor due to adiabatic compression. Instead the total air temperature ($T_\mathrm{total}$, TAT) will be measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The relation between the measured total air temperature and the static temperature is given by: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{T_\mathrm{total}}{T_{s}}={1+\frac{\gamma -1}{2}M_a^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the measurement probe may not recover all the energy from the adiabatic heating a correction factor is introduced: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{T_\mathrm{total}}{T_{s}}={1+\frac{\gamma -1}{2}eM_a^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This 'recovery factor' $e$ is determined empirically for the temperature sensor used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The display on the EFIS will show the OAT, which may be slightly off if $e$ is not entirely correct. This will also affect the &quot;true&quot; airspeed indication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To conclude; anything indicated in the cockpit can contain measurement errors, regardless whether it is called 'indicated' or 'true'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the introduction of digital flight data systems the error correction tables have been moved from the manuals to the computer, which automatically corrects for them. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-29T14:34:57.307" LastActivityDate="2015-05-29T14:34:57.307" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15197" PostTypeId="2" ParentId="15190" CreationDate="2015-05-29T14:28:26.957" Score="3" Body="&lt;p&gt;Really not sure what you're asking, nor do I know what these terms you've found mean, so let's start with these drawings and see where we end up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;DC-9&lt;/strong&gt; Bleed air enters from the engine (or APU) at bottom left of this drawing and enters the primary heat exchanger. Then it enters the compressor in the ACM and then on to the secondary heat exchanger. From here it enters the turbine and this is the point that the heat loss occurs and cold air enters the water separator and then the cabin of the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the anti-ice screen and the pack anti-ice valve which adds a little heat if the air exiting the turbine is too cold and is causing ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The water separator is a cone-shaped cage with a heavy cotton bag over it. This collects condensation in the air and dumps it on to the face of the secondary heat exchanger to cool and improve it's efficiency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature in the cabin is controlled by the temperature control valve on the left side of the drawing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h390Z.png&quot; alt=&quot;DC-9&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;737&lt;/strong&gt; This system is very similar to the DC-9 and really the main difference is that the pack anti-ice valve here is operated electrically, while on the DC-9 it is done mechanically with a pneumatically operated valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aiER6.png&quot; alt=&quot;737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;757/767&lt;/strong&gt; This is a much different system, many more electrical sensors and control. The pack cooling fan is an integral part of the ACM, where on the other two systems they are separate components. The water separators are much more advanced and don't require regular maintenance like on the other systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/H46Bz.png&quot; alt=&quot;757/767&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, these three systems are all basically the same with the only real difference being how they are controlled and some of the ancillary components.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-05-29T14:28:26.957" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15198" PostTypeId="2" ParentId="15163" CreationDate="2015-05-29T14:32:03.807" Score="2" Body="&lt;p&gt;For your requirement to use a battery for silent takeoff and landing, electrically driven propellors (or ducted fans) would certainly be good enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirement you mentioned for 350 mph to 550 mph is really only for cruise, which presumably would use a turbofan (or possibly turboprop) - and recharge the battery at the same time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I would guess what you want is a fairly high performance ducted fan which can be driven by either electric motor for silence or by a conventional turbine at cruise - a bit like a turboprop.  The question is then how do you arrange for an exchange between the two power sources.  (I assume two sets of engines wouldn't be possible, though perhaps they could be?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Edited to add... your electric motors still need full power to takeoff.  So why not run the motor all of the time, and use an auxiliary turbine engine to provide the electrical power at cruise?  Not unlike a hybrid car.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2015-05-29T14:38:57.407" LastActivityDate="2015-05-29T14:38:57.407" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15199" PostTypeId="2" ParentId="15181" CreationDate="2015-05-29T15:32:21.307" Score="6" Body="&lt;p&gt;Based on your question, it sounds like you are referring to fingertip.  In fingertip, yes you are correct, it is exhausting to stay in position for any extended length of time.  This is why it is not flown much (really only time is transiting through the weather, and even then you have radar trail and instrument trail).  Besides TAC (see below), the other position you'll find yourself in at times is route, which is a much more relaxed position but allows the formation to maneuver easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tactical formations like offset (container), spread, wall, wedge, etc. are flown instead.  This relieves the wingmen of constantly having to focus on 1 and can handle other tasks such as clearing, sensor management, backing up lead, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, I've always noticed flying formation in actual AF sims to be harder than the real jet.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-05-29T15:32:21.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15200" PostTypeId="2" ParentId="15194" CreationDate="2015-05-29T17:18:25.980" Score="2" Body="&lt;p&gt;Equivalent airspeed is not speed at all. It is dynamic pressure, indicated as speed at which that dynamic pressure would occur at sea-level standard conditions. And indicated airspeed is equivalent airspeed plus measurement errors (calibrated airspeed is cleared of those errors, that can be effectively estimated).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there is an indicated/equivalent airspeed and there is true airspeed and they are different physical quantities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no quantity that would be expressed as Mach number, but would actually have different physical significance. So “Mach number” only has one meaning. How it is measured and what are the errors is already well covered by the other answers.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-05-29T17:18:25.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15201" PostTypeId="1" AcceptedAnswerId="15205" CreationDate="2015-05-29T18:03:28.213" Score="16" ViewCount="6256" Body="&lt;p&gt;Do pilots have the &quot;ground speed&quot; information available?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, how is the ground speed measured? Or do they rely on GPS info to calculate it?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="19" LastEditDate="2015-05-30T17:38:15.293" LastActivityDate="2015-05-30T17:40:27.520" Title="How is the actual ground speed of an airliner measured?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;&lt;groundspeed&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15202" PostTypeId="2" ParentId="15201" CreationDate="2015-05-29T18:16:27.557" Score="3" Body="&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_speed&quot; rel=&quot;nofollow&quot;&gt;simple definition&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ground speed can be determined by the vector sum of the aircraft's&#xA;  true airspeed and the current wind speed and direction; a headwind&#xA;  subtracts from the ground speed, while a tailwind adds to it. Winds at&#xA;  other angles to the heading will have components of either headwind or&#xA;  tailwind as well as a crosswind component.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The issue with using GPS to determine airspeed is that a GPS does not know what the winds are. Although, weather forecast data can provide approximate wind velocity (direction and speed), it is not precise enough for situations where a few knots makes the difference between life and death.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-05-29T18:16:27.557" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15204" PostTypeId="2" ParentId="15201" CreationDate="2015-05-29T18:36:26.923" Score="5" Body="&lt;p&gt;Ground speed and ground track are available and are determined by GPS.  Comparing two GPS derived locations will yield a velocity vector and ground speed is its magnitude.  This is also how winds are derived -- the difference between airspeed and heading compared to groundspeed and ground track.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that availability varies by airplane and installed equipment.  Any modern airliner will have this info on a primary or secondary display.  Smaller general aviation aircraft with an technologically advanced cockpit will have this info as well.  Smaller general aviation planes with just a GPS unit will have access to the information but it may not be convenient to reference. Those without even GPS will only be able to derive groundspeed from airspeed and reported winds with a flight computer manually.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-05-29T18:36:26.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15205" PostTypeId="2" ParentId="15201" CreationDate="2015-05-29T19:01:28.580" Score="21" Body="&lt;p&gt;There are generally two ways of determining the ground speed from within the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first is by using an inertial navigation system. This consists of a number of accelerometers and gyroscopes that measure all accelerations and rotations of the aircraft throughout a flight. By mathematically integrating all measurements this navigation system is able to compute the speed and position of the aircraft at any time. The accuracy will degrade over time but ground speed is usually not far off, otherwise position would be far off very soon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second method uses external radio signals. Nowadays this is mostly GPS, but ground speed is also determined by using a number of VOR (VHF Omnidirection Range) and/or DME (Distance Measuring Equipment) stations. These navigation beacons are widely available over most continents. A navigation computer would select the right set of beacons and by analysing the rate of change of the beacon bearings / distances the aircraft's speed can be determined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern navigation systems combine all these methods into a one solution. GPS, inertial navigation and DME measurements are then fused mathematically together to obtain a highly accurate and robust position and ground speed. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-05-30T17:40:27.520" LastActivityDate="2015-05-30T17:40:27.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15206" PostTypeId="2" ParentId="15180" CreationDate="2015-05-29T21:30:27.343" Score="4" Body="&lt;p&gt;There could be two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Performance: The more forward c.g. location demands more speed, so the wing can create enough lift to counteract the downforce from the tail. To keep the minimum speed below the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_149&quot; rel=&quot;nofollow&quot;&gt;61 knots mandated by FAR part 23&lt;/a&gt;, the forward c.g. location at high gross weight needs to be restricted.&lt;/li&gt;&#xA;&lt;li&gt;Stick forces: A more forward c.g. location translates into bigger elevator deflection angles for maneuvering. Again, the airworthiness requirements put lower and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_1143&quot; rel=&quot;nofollow&quot;&gt;upper limits&lt;/a&gt; on them, and it could be that the upper limits are exceeded with the combination of high gross weight and forward c.g. location.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-05-29T21:30:27.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15207" PostTypeId="1" AcceptedAnswerId="15208" CreationDate="2015-05-29T21:36:16.533" Score="14" ViewCount="5992" Body="&lt;p&gt;I've read &lt;a href=&quot;https://aviation.stackexchange.com/questions/2126/why-dont-aeroplanes-automatically-put-out-engine-fires&quot;&gt;this&lt;/a&gt; question and its answers basically asking why putting out an engine fire is not left to the computer but a manual task. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the points mentioned is that there simply might be a sensor error or similar and the engine isn't actually on fire, in which case you obviously don't want the computer to needlessly shut down an engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question however is, &lt;strong&gt;how do the pilots assess wether the engine is actually on fire or not?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All planes I've been on had their engines very close to the aircraft and I doubt they are easily if at all visible from the flight deck. I would assume a good indicator might be the loss of thrust, but that could also be detectable by a computer. Do the pilots have cameras they can activate to check on the engines, or do they call the cabin personal and ask them to take a peek, do they walk out and check or is it based on how loud the passengers scream in the back? I guess all of these work, but what is the common procedure?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2019-03-02T14:27:18.713" Title="How does the pilot check if an engine fire is real?" Tags="&lt;emergency&gt;&lt;fire&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15208" PostTypeId="2" ParentId="15207" CreationDate="2015-05-29T22:48:33.547" Score="16" Body="&lt;p&gt;Engine fire implies that there is a strong heat source (commonly a fire, but could be a hot substance) in a location there should not be, usually around the outside of the engine.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine fires do not necessarily need to be connected with a loss of thrust.&lt;/li&gt;&#xA;&lt;li&gt;Visually, they are pretty diverse- there may be smoke, there may be little smoke (aside from that, what would you do at night?).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The general rule is to treat the cockpit instrument indications as real every time. You do not need a visual confirmation.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would rather take safe action a thousands times too many than one time too little. The aircraft is designed to fly on one engine and it's probably one of the most common exercises for pilots in simulators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are correct that sensors do get it wrong. Here is a very recent &lt;a href=&quot;http://avherald.com/h?article=48630eac&quot;&gt;incident&lt;/a&gt; that involved just that. The reason for the sensor discussion is that a decision is only as good as the information you can base it on, and a human is generally a better decision maker than a computer as it currently stands. Take &lt;a href=&quot;http://avherald.com/h?article=462beb5e&quot;&gt;this&lt;/a&gt; very complicated and confusing situation for instance- how would a computer decide and respond?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no physical damage in hitting the fire button which will shut the engine down. Discharging the Halon fire agents would normally require a new bottle. It is a bit of a 'hard' engine shutdown: it cuts fuel, bleed air, electricity and hydraulics. If the fire warning (i.e. heat source) persists, you generally escalate it to discharging fire agents, although in most cases shutting the engine off is a sufficient measure.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-05-30T10:17:31.703" LastActivityDate="2015-05-30T10:17:31.703" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15209" PostTypeId="1" CreationDate="2015-05-29T22:51:03.213" Score="4" ViewCount="162" Body="&lt;p&gt;Professional technicians, who work in aircraft maintenance, usually obtain some sort of national certification, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's suppose someone got training and certification in one country, and wants to migrate to another country. Does he require some certification to work there as an aircraft technician? How is it achieved?&lt;/p&gt;&#xA;" OwnerUserId="8687" LastEditorUserId="65" LastEditDate="2015-06-01T14:14:34.380" LastActivityDate="2016-10-26T19:26:05.193" Title="Do aircraft technicians need additional certifications to work in other countries?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;general-aviation&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15211" PostTypeId="2" ParentId="8129" CreationDate="2015-05-29T23:51:17.587" Score="0" Body="&lt;p&gt;Although there is not a rule about that, but since you are in a large group with many children, you may call the airline directly to see if they can make a special seat arrangement. Usually, they would do so.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-05-29T23:51:17.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15212" PostTypeId="1" AcceptedAnswerId="15232" CreationDate="2015-05-30T01:23:19.830" Score="11" ViewCount="5973" Body="&lt;p&gt;Does anyone know how heavy are the combined landing gear on a Boeing 747?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be interesting if someone has also weight statistics per gear (nose gear and the four other main gear).&lt;/p&gt;&#xA;" OwnerUserId="3663" LastEditorUserId="5517" LastEditDate="2016-09-12T20:32:17.987" LastActivityDate="2017-06-19T10:47:44.337" Title="How heavy are the Boeing 747 landing gear?" Tags="&lt;airliner&gt;&lt;landing-gear&gt;&lt;boeing-747&gt;&lt;weight&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15213" PostTypeId="2" ParentId="15165" CreationDate="2015-05-30T01:48:29.393" Score="2" Body="&lt;p&gt;One area not mentioned is in aircraft manufacturing. Right now I've heard around 40% or greater of the cost of a new airframe is the liability insurance and all the paperwork and testing for every component that the aircraft uses. Just imagine what the training and general aviation industry would be like if we went back to sane pricing for new Cessna 172s or similar... instead of broaching 360k, for a simple 4 seat trainer, could be around 180k or less.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-05-30T01:48:29.393" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15214" PostTypeId="2" ParentId="15191" CreationDate="2015-05-30T02:38:59.790" Score="5" Body="&lt;p&gt;The autopilot in the super hornet is inferior to what you'd find in a typical Southwest flight.  It's got a heading hold, waypoint couple, baroalt hold and auto throttles, but none of them are linked together and all operate independently of each other.  There is no vertical speed hold, and no FMS to tie it all together.  The one thing it has is autotrim, but then again, so does the average Airbus.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-05-30T02:38:59.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15215" PostTypeId="2" ParentId="15209" CreationDate="2015-05-30T03:11:15.427" Score="5" Body="&lt;p&gt;I don't have personal experience, but this is absolutely something you can do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately many countries do not have the exact same standards or licensing scheme, so often your licence is not automatically converted, but you rarely need to start from scratch. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if you wanted to come to Australia, you would need to attend a CASA approved Part 147 training organisation, which are located around the world. They will assess you, possibly provide you with some extra training, following which you can apply for an Australian Part 66 engineer licence. Once you get that licence you shouldn't have too much difficulty migrating, but that's a discussion outside of my league. More details on this conversion process are on the &lt;a href=&quot;http://casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90484&quot;&gt;CASA website&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-05-30T03:11:15.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15216" PostTypeId="1" CreationDate="2015-05-30T04:16:27.750" Score="10" ViewCount="1329" Body="&lt;p&gt;I haven't noticed any sort of plug door, so how do pilots board the B-2?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="14897" LastEditDate="2018-06-03T18:10:25.337" LastActivityDate="2018-06-03T18:10:25.337" Title="How does a pilot board a B-2 Spirit?" Tags="&lt;doors&gt;&lt;b-2&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15217" PostTypeId="2" ParentId="15216" CreationDate="2015-05-30T05:39:21.577" Score="12" Body="&lt;p&gt;There is a hatch and a ladder in the &lt;em&gt;bottom&lt;/em&gt; of the front fuselage, through which the pilots enter the bomber, as seen &lt;a href=&quot;http://media.airspacemag.com/images/Stealth-Bomber-Elite-631.jpg&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f1ZiE.jpg&quot; alt=&quot;Pilot hatch seen slightly to the left of the cockpit.&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8074" LastEditorUserId="8074" LastEditDate="2015-05-30T21:27:54.723" LastActivityDate="2015-05-30T21:27:54.723" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15218" PostTypeId="1" AcceptedAnswerId="15219" CreationDate="2015-05-30T06:02:19.560" Score="15" ViewCount="2224" Body="&lt;p&gt;If you observe a plane flying whilst on the ground, plenty of times you will see contrails:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/GD7QM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are they not visible from the plane itself when sitting in the most rear part of the cabin even by trying to look towards the rear of the plane fuselage? They seem to be quite close to the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing that they form due to the heat, they should be seen quite close to the engine.&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-06-11T12:09:06.450" Title="Why are contrails not visible from the cabin?" Tags="&lt;contrails&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15219" PostTypeId="2" ParentId="15218" CreationDate="2015-05-30T08:21:00.537" Score="17" Body="&lt;p&gt;Contrails do not form due to heat, but in fact the opposite: cold. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They occurs when water from fuel combustion exceeds the saturation point of the ambient air. As it is unable to hold more water it turns into water vapor instead. This freezes at sub-zero temperatures into ice crystals and you end up essentially making a cloud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the saturation point is connected to temperature (think mixing sugar in cold vs. hot water) this happens a bit back from the fuselage when the exhaust cools down. The point where this happens is dependent on the outside temperature and the existing humidity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under the correct conditions &lt;strong&gt;you can see contrails from the cabin&lt;/strong&gt;, but usually they crystallize too far back to be seen. See &lt;a href=&quot;https://www.youtube.com/watch?v=ATttMM5nFO8&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;https://www.youtube.com/watch?v=xMZe_Iep8TM&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; video for it occurring.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-01T20:55:54.697" LastActivityDate="2015-06-01T20:55:54.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15220" PostTypeId="2" ParentId="15218" CreationDate="2015-05-30T08:25:12.737" Score="26" Body="&lt;p&gt;The distance between the engine and the start of the contrail depends on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the engine type&lt;/li&gt;&#xA;&lt;li&gt;the temperature of the outside air&lt;/li&gt;&#xA;&lt;li&gt;the moisture content of the outside air. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Usually the contrails don't form before the tail of the aircraft, but in extreme cold or humid air contrails can be seen forming just behind the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On larger aircraft you have a better change of seeing the contrail from inside the aircraft. On the 747 you can often spot them for the window of the rear passenger door. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/X6YzM.png&quot; alt=&quot;Boeing 737-800 contrail (luchtzak.be)&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/oExf5.jpg&quot; alt=&quot;Boeing 777 contrail&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="65" LastEditDate="2015-06-01T14:24:00.827" LastActivityDate="2015-06-01T14:24:00.827" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15221" PostTypeId="2" ParentId="15218" CreationDate="2015-05-30T10:24:33.803" Score="10" Body="&lt;p&gt;This is more a comment than an answer, but since I have a picture, I write it as answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has alredy been written that contrails may form aside or behind an aircraft, so you may or may not be able to see them from the rearmost seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But also note that the blast stream can be much lower than what you would expect. In a two-engine aircraft, you have to look down from the upper edge of the window, and even then, the stream will be on the lower border of your field of view. Of course, the stream of the outer engines of four-engine aircrafts will be more centered in your field of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying over a scenery with high optical contrast, you can recognize the blast as a sharply defined region where the view is very blurry, as in the lower right region on this picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FA8zk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was taken from the last seat row of a A340 after takeoff at Chicago O'Hare, and you can see the blast of the outer engine. (And yes, the outer stabilizer is in a little weird condition...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, look out for these blurry regions, that's where contrails &lt;em&gt;may&lt;/em&gt; form.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; (just for fun)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming home from vacation yesterday, I noticed another sign for contrails from your aircraft: The contrail's shadow:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/WuVWb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Unfortunately, the clouds became less dense when I made the photo, before I could also see a good shadow of the aircraft itself.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-06-11T12:09:06.450" LastActivityDate="2015-06-11T12:09:06.450" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15222" PostTypeId="1" AcceptedAnswerId="15253" CreationDate="2015-05-30T11:39:14.273" Score="17" ViewCount="5087" Body="&lt;p&gt;While not a frequent flyer, I did fly common airliners quite a lot, and each time the (very) low sound quality of onboard public adress system has always struck me. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We all know technology makes it possible to have a &quot;HiFi&quot; sound quality almost everywhere, so &lt;strong&gt;why&lt;/strong&gt; don't major manufacturers (Boeing and Airbus) provide better sound quality systems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this is of course not mandatory to make an airplane fly, it is related to passenger safety. Better sound quality would allow crew instructions to be better understood during the pre-takeoff briefing and in the event of an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have flown with several airlines, and there are already enough other factors that make it difficult to understand what's being said on PA:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On board noise: air conditioning, running engines, neighbors talking, kids crying, ...&lt;/li&gt;&#xA;&lt;li&gt;Strong or difficult english accent when either the crew or the passenger are not english-native speakers.&lt;/li&gt;&#xA;&lt;li&gt;Crew speaking really fast.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The airplane companies can't do much on the above items, but they can improve the technical aspects. Of course, I do understand that this would require increasing weight (loudspeakers are heavy...) thus reducing commercial load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Side question:&lt;/strong&gt; How do US/EU regulations handle this point? Do they have any specs on sound quality requirements?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note: I haven't tried recent planes such as A380, so maybe it has been improved.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8641" LastEditorUserId="2143" LastEditDate="2015-05-31T15:34:43.037" LastActivityDate="2015-06-01T15:56:38.430" Title="Why is the sound quality of onboard public address so bad?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;regulations&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15225" PostTypeId="2" ParentId="14888" CreationDate="2015-05-30T14:43:42.223" Score="14" Body="&lt;p&gt;While the aircraft you mention would appear to be similar, this is not really entirely true. Specification wise yes, but the period it was designed in has a huge impact. For instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The first flight of the Boeing 737 was in 1967, with the Airbus A320 following considerably later in 1987. (20 years later)&lt;/li&gt;&#xA;&lt;li&gt;Boeing 747 first flew in 1969, the Airbus A380 followed in 2005. (36 years later)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each redesign is expensive and time-consuming so if there is no conceivable benefit it is not done. There is no clear cut equation on when a certain type of slat and flap mechanism is chosen: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The operating environment changes over time. One important consideration is the landing speed (and corresponding runway length). This for instance limited the Boeing 707 greatly, and it was likely that Boeing might not wish to run into the same problem with the B747 to enable it to serve as many markets as possible at a time when airports were not so advanced. For this reason they put in the very complicated triple-slotted flaps. (For comparison, look at the A380 which has caused headaches as airport operators have to modify and/or rebuild facilities to accommodate it)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft have become lighter over the years with the introduction of new materials, production techniques and better optimized engineering.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Technology has become better at modelling, so we can be less conservative in design choices as there is a better idea of the end result. This applies not only to the structure but also aerodynamics.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The bottom line is that you take the values and look at a few different designs. You choose the one that best fulfills your criteria (not only in performance but also what you can build) and go with it, and this choice would change over time. If the Boeing 737 would be built today, the details most probably be fairly different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What does this mean?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The A380 for instance only has single slotted slats. When the B747-8i recently received a new wing design, it shifted from triple to double and single slotted flaps.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Both the A350 and B787, designed roughly around the same period, both have the rear single slotted flaps and (to large extent) the same slat design.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8375" LastEditDate="2016-10-27T19:00:53.740" LastActivityDate="2016-10-27T19:00:53.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15226" PostTypeId="2" ParentId="15222" CreationDate="2015-05-30T15:55:16.823" Score="8" Body="&lt;p&gt;The PA (Public Address) system is composed by a band-pass filter between a range of frequencies $f \in [f_i , f_f]$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quality of the sound is affected because the voice frequencies may exceed this range and thus, the band-pass filter rejects these peaks, that are exceeding the filter range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember how a band-pass filter works:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9jL5L.gif&quot; alt=&quot;Band-pass filter amplitude curve.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frequencies below $f_i$ are not allowed nor the frequencies above $f_f$. Nevertheless, when the frequencies are outside of the &lt;strong&gt;bandwidth&lt;/strong&gt; range (determined by the $\Delta f=f_2-f_1$ at which the gain has a value of $\mathrm{gain_{max}}-3$ $\mathrm{dB}$), the quality of the sound gets worse and therefore, from the cabin we are listening to a dimmed sound of the flight crew voice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the newer aircraft PA systems are done by using DSP (Digital Signal Processing) systems, also within the limited range, but the quality of the sound is more improved.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt; Dimov Stojce Ilcev, &quot;Global Aeronautical Communications, Navigation and Surveillance (CNS)&quot;, June, 2013.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="8407" LastEditDate="2015-05-30T16:39:56.860" LastActivityDate="2015-05-30T16:39:56.860" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15227" PostTypeId="1" AcceptedAnswerId="15231" CreationDate="2015-05-30T15:56:05.997" Score="6" ViewCount="2462" Body="&lt;p&gt;What is the front glass in fighter planes called? I mean the one which had the reticle marked in them not the canopy glass. Cockpit part on google doesn't seem to tell what I want to know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any other uses of it besides targeting, because I have seen them only in fighter planes/jets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When were they first employed?&lt;/p&gt;&#xA;" OwnerUserId="8215" LastEditorUserId="1696" LastEditDate="2018-04-23T17:07:32.653" LastActivityDate="2018-04-23T17:07:32.653" Title="What is the front glass in fighter planes called?" Tags="&lt;fighter&gt;&lt;display&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15228" PostTypeId="1" CreationDate="2015-05-30T18:04:45.440" Score="3" ViewCount="67" Body="&lt;p&gt;I was surprised to learn that an &lt;a href=&quot;http://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow&quot;&gt;inertial navigation system&lt;/a&gt; even works at all; I'd expect that the integration drift would throw the &lt;em&gt;velocity&lt;/em&gt; measurement off badly enough, not to mention the position. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2275/what-is-an-inertial-navigation-system-how-does-it-work&quot;&gt;Other questions&lt;/a&gt; have asked about how these systems work, and the answers have explained that cross-checks with other measurements which give absolute position (e.g. GPS) improve accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But given a state-of-the art INS which operates in isolation (no interfacing with airspeed, GPS, etc) from takeoff, how much drift could we expect for, say, a normal transatlantic flight? Does this change if the aircraft flies through turbulence?&lt;/p&gt;&#xA;" OwnerUserId="8693" LastActivityDate="2015-05-30T18:04:45.440" Title="How accurate is an Inertial Navigation System" Tags="&lt;navigation&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-05-30T18:47:50.863" ContentLicense="CC BY-SA 3.0" />
  <row Id="15229" PostTypeId="2" ParentId="9243" CreationDate="2015-05-30T18:27:21.270" Score="0" Body="&lt;p&gt;I forget which incident triggered it, but I recall some years ago that an inventor and his invention (for which he sought a patent), proposed to do almost exactly this, and was featured on a news story. The inventor felt that he was being brushed off for no good reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, then as now, it's an unfeasible idea for numerous reasons including cost, weight, reliability, and insignificant or non-existent window of opportunity for effective use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider: in exactly what sort of scenario could such a system actually offer a favorable outcome? How would it be determined that activation of the system is the correct action? If so, what preparation within the cabin would be needed pre-activation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bad things happen very rarely, extremely rarely at altitude (where any sort of parachute system would have a chance of deploying effectively) and happen without warning. By the time the emergency is recognized, it may be too late to push the button on such a system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point: it is always better all around to prevent an emergency from ever occurring than it is to develop systems to be activated in response, especially when the response is as complex and expensive as a break-apart and parachute system.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-05-30T18:27:21.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15230" PostTypeId="1" CreationDate="2015-05-30T19:04:24.653" Score="5" ViewCount="15696" Body="&lt;p&gt;Fighter aircraft today are capable of flying several times the speed of sound. Why is it that the sonic boom only occurs at the moment the plane crosses Mach 1?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="946" LastEditDate="2015-05-31T09:52:20.767" LastActivityDate="2015-06-01T03:25:50.580" Title="How come sonic booms only occur once at the speed of sound and not multiple times?" Tags="&lt;supersonic&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ClosedDate="2015-06-01T06:45:46.530" ContentLicense="CC BY-SA 3.0" />
  <row Id="15231" PostTypeId="2" ParentId="15227" CreationDate="2015-05-30T21:45:10.973" Score="8" Body="&lt;p&gt;It's a &lt;a href=&quot;http://en.wikipedia.org/wiki/Head-up_display&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heads Up Display&lt;/a&gt;, or HUD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h99PXm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The HUD can display a number of different pieces of information, including performance data such as airspeed, altitude, and attitude, navigation data such as waypoints or ILS glideslope, or weapons data such as the selected weapon or the targeting reticle you mentioned. Thus, its uses are varied - depending on how sophisticated the system, basic aircraft control may be accomplished using only the HUD. In some modern fighters, there may be additional data on a Helmet Display (or in the case of the F-35, the helmet may have the only display).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not just used on fighters - some airliners, cargo planes, and trainers have HUDs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YJ6Gnm.jpg&quot; alt=&quot;C-17 HUD&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.dutchaviationsupport.eu/00-HTMS/c-17ppm.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-17&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RiNcAm.jpg&quot; alt=&quot;T-38 HUD&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(T-38)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xdhr9m.jpg&quot; alt=&quot;Airbus HUD&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://onboard.thalesgroup.com/2012/07/23/qatar-airways-selects-dual-hud-system-option-for-its-new-a350-xwb-and-a380-airbus-fleet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A380&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your last question, per fooot's comment, &lt;a href=&quot;https://aviation.stackexchange.com/questions/7578/what-is-the-history-of-glass-cockpits/7602#7602&quot;&gt;this question and answer&lt;/a&gt; has more information.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Blackburn_Buccaneer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Blackburn Buccaneer&lt;/a&gt; was the first production aircraft with a HUD and entered service in 1963. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-05-30T21:45:10.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15232" PostTypeId="2" ParentId="15212" CreationDate="2015-05-30T21:58:36.107" Score="17" Body="&lt;p&gt;It seems I misspoke in my comment in which I gave the moments for 747-400BCF gear retraction. I didn't realize the component weights were further on in the document I referenced. The weights for the BCF are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;body gear 6447 lbs (2924 kg) each&lt;/p&gt;&#xA;&#xA;&lt;p&gt;wing gear 6508 lbs (2952 kg) each&lt;/p&gt;&#xA;&#xA;&lt;p&gt;nose gear 3157 lbs (1432 kg)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, @Gurkan's comment is relevant in that you have to decide what all should be considered as part of the gear. So, I put up a PDF of the &lt;em&gt;WEIGHT AND BALANCE CONTROL AND LOADING MANUAL&lt;/em&gt; for each of two 747 freighter variants. You can access them at &lt;a href=&quot;http://terryliittschwager.com/wbmanuals.php&quot; rel=&quot;noreferrer&quot;&gt;terryliittschwager.com/wbmanuals.php&lt;/a&gt;. The most relevant sections are 1-86-041 and 051.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="10076" LastEditDate="2017-06-19T10:47:44.337" LastActivityDate="2017-06-19T10:47:44.337" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15233" PostTypeId="1" CreationDate="2015-05-30T22:58:25.053" Score="6" ViewCount="382" Body="&lt;p&gt;I fly in the Bay Area. I sometimes like to fly over SF through the San Francisco Class B. If I am in contact with Norcal Approach and in their airspace, I can ask them for an exception and they can authorize it. But, I could also be talking to the tower, and could also be talking to Oakland Tower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All three of the following agencies have authority over sections of airspace that overlap with the stadium TFRs at the Giants stadium (see image).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Oakland tower (class C)&lt;/li&gt;&#xA;&lt;li&gt;San Francisco tower (core class B)&lt;/li&gt;&#xA;&lt;li&gt;Norcal approach (outside core class B)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My question is: which of these three agencies have the authority to grant me an exception to the stadium TFR?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Image is SF TAC with TFR plotted by Foreflight.)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/cJr61.jpg&quot; alt=&quot;TAC&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-05-31T03:40:09.020" Title="Who has authority over stadium TFR exceptions in VFR flight?" Tags="&lt;airspace&gt;&lt;tfr&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15234" PostTypeId="1" AcceptedAnswerId="15262" CreationDate="2015-05-31T00:16:50.357" Score="23" ViewCount="9272" Body="&lt;p&gt;From what I've read about Airbus planes is that their fly-by-wire system works by having three different flight control computers calculate what the plane should be doing and then vote on all the three outcomes about which to take. I would hope that they all give the same result all of the time, but as I understand it this is used to make sure that decisions based on faulty data doesn't scatter the plane across the ground. How does this actually work? How does the computer vote which result is the correct one, is it just a majority vote? What happens when all three outcomes disagree?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, is this system only in place when operating in normal law? And are they actually different software implementations or is the only difference that they are fed input from different redundant sensors?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastActivityDate="2017-12-14T08:57:54.223" Title="How does the Airbus flight computer's voting system work?" Tags="&lt;flight-controls&gt;&lt;airbus&gt;&lt;fly-by-wire&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15235" PostTypeId="1" CreationDate="2015-05-31T00:30:08.950" Score="4" ViewCount="519" Body="&lt;p&gt;If you have an airplane with electric propellers for take off and landing and you have a turbofan/jet to reach higher speeds for cruise.&#xA;For example, electric propellers can go to 250mph and turbofan to 550mph&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Do you switch off the electric propellers or leave them on ? &lt;/li&gt;&#xA;&lt;li&gt;Do they work in conjunction ? &lt;/li&gt;&#xA;&lt;li&gt;What is the effect on the propellers when the turbofan reaches 550mph ?&lt;/li&gt;&#xA;&lt;li&gt;Is the thrust added if both engines are working ?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8664" LastEditorUserId="5517" LastEditDate="2015-06-01T12:24:10.220" LastActivityDate="2015-06-04T09:34:11.833" Title="Electric Airplane - Hybrid / dual type engines how would that work?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;turbofan&gt;&lt;electric-engine&gt;&lt;aircraft-physics&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15237" PostTypeId="1" AcceptedAnswerId="15241" CreationDate="2015-05-31T03:38:39.140" Score="3" ViewCount="3009" Body="&lt;p&gt;&lt;sub&gt;&lt;sub&gt;I am not a pilot - just a student &amp;amp; play Ace Combat  sometimes&lt;/sub&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I turned off the flight turn assistant in the Ace Combat flight simulator/game &amp;amp; now I have to manually control bank &amp;amp; pitch to turn. I also like to use a little yaw for stabilizing myself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I am not wrong - both pitching &amp;amp; rolling are controlled by the &lt;em&gt;control yoke&lt;/em&gt; in jets. So, when going for a right turn from level flight, what does the pilot do:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Push the yoke a little right (attain 90+ degree rightward roll) and then pull the yoke towards him (to pitch up - i.e. actually execute the right turning arc). OR&lt;/li&gt;&#xA;&lt;li&gt;Pull the yoke in a diagonal way i.e. towards SouthEast (assuming pilot was initially heading north) or 4'o clock - and the flight's internal computers break down yoke movement movement into respective pitch and roll magnitudes.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Just curious.&lt;/p&gt;&#xA;" OwnerUserId="8215" LastEditorUserId="1961" LastEditDate="2017-12-25T01:05:40.080" LastActivityDate="2020-11-17T14:22:30.927" Title="How to turn a fighter jet?" Tags="&lt;flight-training&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15238" PostTypeId="2" ParentId="15233" CreationDate="2015-05-31T03:40:09.020" Score="3" Body="&lt;p&gt;The answer will vary based on the location - San Francisco, Los Angeles, and New York may each have different arrangements. However, in general, it'll come down to how the different ATC facilities have the situation worked out with each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stadium TFR itself does not help much. The relevant section &lt;a href=&quot;http://tfr.faa.gov/save_pages/detail_4_3621.html&quot; rel=&quot;nofollow&quot;&gt;states that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;THE RESTRICTIONS DESCRIBED ABOVE DO NOT APPLY TO THOSE AIRCRAFT AUTHORIZED BY AND IN CONTACT WITH ATC FOR OPERATIONAL OR SAFETY OF FLIGHT PURPOSES&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Any of those facilities could provide the authorization - so it's then down to which &lt;em&gt;will&lt;/em&gt; do so. The answer to that will depend on the structure of how the facilities work with each other. The ATC facilities will have Letters of Agreement which state that a given area of airspace is managed by a given facility, as well as how handoffs are handled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The facility that can provide flight following is also the facility that can authorize you into the TFR in that area. To figure that out, all you have to do is ask: call up Norcal Approach or Oakland Tower, and ask for flight following. If they can do that, then they're the right folks to ask about transiting the TFR. If not, they'll give you another frequency to try. Of course, just because they have authority over the airspace doesn't mean they'll grant the request.&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-05-31T03:40:09.020" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15239" PostTypeId="1" CreationDate="2015-05-31T04:04:43.503" Score="12" ViewCount="2778" Body="&lt;p&gt;I saw, on National Geographic, two well built navy guys lifting a &lt;em&gt;comparatively&lt;/em&gt; small missile to be attached on wings of an F-18 Super Hornet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when one missile on left wing is launched doesn't it drastically shift CoG of jet? Who copes with this shift&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Computer &amp;amp; other stuff internally adjusts the &lt;em&gt;zero&lt;/em&gt; position of flight controls to attain level flight. In this case what is the basis of detecting shift in flight control made by pilot - the old zero or the new zero?&lt;/li&gt;&#xA;&lt;li&gt;The pilot by shifting position of flight controls, using hands &amp;amp; feet, in &lt;em&gt;non-zero&lt;/em&gt;ish positions to maintain level flight despite changed CoG. If yes, isn't it detrimental to pilot's performance in a dog fight?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8215" LastEditorUserId="1696" LastEditDate="2018-04-22T18:42:42.550" LastActivityDate="2018-04-23T11:07:39.933" Title="How do pilots maintain level flight after launching missile?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;flight-controls&gt;&lt;fighter&gt;&lt;dogfighting&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15240" PostTypeId="2" ParentId="2873" CreationDate="2015-05-31T07:38:28.000" Score="5" Body="&lt;p&gt;There is progress please take a look at the &lt;a href=&quot;https://en.wikipedia.org/wiki/ICON_A5&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICON A5&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cirrus_Vision_SF50&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cirrus Vision SF50&lt;/a&gt; cockpit controls.&lt;/p&gt;&#xA;&lt;p&gt;And I agree a lot of Pre-Flight checks and controls could be simplified or computer checked.&lt;/p&gt;&#xA;&lt;p&gt;The big difference between a car (simple interface) and a plane is if there is an issue with your car you pull it aside and with a plane you drop from the skies :(  although autogyro's like the Cavalon dont have that issue :)&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/q36Du.jpg&quot; alt=&quot;ICON A5 cockpit&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/C7qNI.jpg&quot; alt=&quot;Cirrus SF50 cockpit&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="8664" LastEditorUserId="2956" LastEditDate="2020-07-22T10:23:11.670" LastActivityDate="2020-07-22T10:23:11.670" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="15241" PostTypeId="2" ParentId="15237" CreationDate="2015-05-31T10:16:59.453" Score="7" Body="&lt;p&gt;I think you are making things too complicated on yourself. To the best of my knowledge, fighter jet controls will in principle behave the same way as almost any other aircraft- they will in general actuate surfaces the same regardless of orientation. A left/right movement controls roll, a backwards/forwards movement controls pitch.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You would push the stick sufficiently to the right to bank until you reach the desired turn rate. You would have to maintain a little right stick to maintain the bank angle. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As you do the above, pull back a little to ensure that the vertical speed remains zero. You also need to add a little rudder to create a coordinated turn.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;See the following images taken from &lt;a href=&quot;http://www.f15sim.com/operation/f15_longitudinal_control.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.f15sim.com/operation/f15_lat_control.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/kTzfe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K1c6y.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-05-31T10:16:59.453" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15242" PostTypeId="1" AcceptedAnswerId="15249" CreationDate="2015-05-31T11:39:13.747" Score="3" ViewCount="1813" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sQMbG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am trying to understand the image above. If you fly in the Northern Hemisphere going west. The image said it's 150 degree if you fly Great Circle while 270 degree flying rhumb line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think about this on a map, how is it possible to be 150 degree? Shouldn't the degree be between north(360) and west(270) as you fly west? I'm so confused. &lt;/p&gt;&#xA;" OwnerUserId="8696" LastEditorUserId="19" LastEditDate="2016-07-28T11:25:36.910" LastActivityDate="2016-07-28T11:25:36.910" Title="How should I interpret the difference in flight direction (azimuth) for great circle and rhumb line?" Tags="&lt;navigation&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15243" PostTypeId="1" AcceptedAnswerId="15244" CreationDate="2015-05-31T12:21:20.997" Score="31" ViewCount="6790" Body="&lt;p&gt;As answered in this &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb&quot;&gt;question&lt;/a&gt;, aircraft need excess power - not excess lift - to climb. This is plausible when the aircraft's thrust vector has a vertical component (its nose and engine points upwards), but I challenge the requirement of excess power for every case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please take a look at the following cart. The thrust gets delivered by a propeller at the rear and the thrust vector is always horizontal. A wing attached to a vertical beam is free to move up and down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BlEjp.png&quot; alt=&quot;cart front view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZZUSw.png&quot; alt=&quot;cart rear view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the cart gets accelerated and reaches a certain speed, the lift acting onto the wing gets greater than the wing's weight, leading to a climb of the wing. Please notice that - because thrust is horizontal - the chemical energy burned goes into kinetic energy of the cart and/or heat energy (due to overcoming drag). No power invested by the propeller goes into potential energy of the wing; the climb of the wing is done purely by lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did I miss something?&lt;/p&gt;&#xA;" OwnerUserId="7331" LastEditorUserId="34686" LastEditDate="2020-11-02T20:21:45.207" LastActivityDate="2020-11-09T10:07:57.917" Title="Is excess lift or excess power needed for a climb?" Tags="&lt;aerodynamics&gt;&lt;aircraft-physics&gt;&lt;lift&gt;&lt;flight-dynamics&gt;&lt;climb&gt;" AnswerCount="8" CommentCount="12" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15244" PostTypeId="2" ParentId="15243" CreationDate="2015-05-31T12:36:39.323" Score="20" Body="&lt;p&gt;As the answers to your original question already explained, you &lt;strong&gt;do&lt;/strong&gt; need extra lift to accelerate upwards. Once the wing is set into a vertical motion, however, lift again exactly equals weight to keep the wing at a constant vertical speed (if we neglect thrust and drag for a moment). No extra lift is needed to maintain that vertical speed. Only when you want to &lt;strong&gt;accelerate&lt;/strong&gt; further up, extra lift is needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The increase in potential energy comes indeed from the propeller, because the lift vector of the climbing wing is tilted backwards, adding a horizontal component that needs to be compensated by extra propeller thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's look at your experiment in detail: I assume the wing has some mass, is rotationally locked and slides up and down that pole without friction. If you accelerate the car, at some point its speed will just be right for the wing to create exactly the lift to cancel out its own weight. At this speed the wing will be stable at any position along the pole. If it slides down a little, its angle of attack $\alpha$ will increase and create more lift, stopping the downward motion. The reverse is true for any upward motion. See below for an illustration of the principle. The cyan vector is the vector sum of the flow due to forward motion (blue) and vertical motion (red), and this is what the wing will &quot;notice&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2hZ6D.png&quot; alt=&quot;flow angles at wing in rest and in motion&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the car accelerates further, the lift will increase and now become greater than the weight. The wing will accelerate upwards until its vertical speed will reduce its angle of attack by enough to reduce the vertical aerodynamic forces to exactly equal its weight. Now you have the same situation as before, but not at zero vertical speed, but at a positive vertical speed which will make sure that the wing pops out at the top of the pole unless there is some stop. When the wing hits the stop, the vertical motion ceases, the angle of attack increases and the wing will lift up not only itself, but also part of the car's weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that I now spoke of the vertical components of the aerodynamic forces, not lift. When drag is added, it will add a vertical component when the wing is in motion. Lift is defined as the sum of aerodynamic forces perpendicular to the flow direction at infinity and drag parallel to it. This cumbersome definition makes sure that local distortions in the flow field do not impact the direction of lift and drag. The direction of lift for the climbing wing will point slightly backwards and the direction of drag slightly downwards. This will add some drag component to the sum of the vertical aerodynamic forces, and lift needs to increase to compensate for this. The horizontal component of lift will now add to the drag and the forces on the pole, so more force from the propeller is needed to push the climbing wing through the air. This extra force is needed to increase the potential energy of the wing on its way up. For a descending wing, the reverse is true: Now drag will add some vertical component and lift will be slightly slower. The forward component of lift will now push against the pole, reducing the force the propeller needs to provide. The reduction in potential energy now reduces the horizontal aerodynamic forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane is slightly different, because it is free to pitch up or down and the angle of thrust will pitch with it. This will enable the pilot to select the flight path and the amount of lift the wing creates, but again the vertical motion will make sure that any excess lift will translate into increased vertical speed and a lower angle of attack, so the excess lift vanishes. In a climb, thrust needs to be bigger than drag in order to increase the potential energy of the airplane, and now the vertical component of the tilted thrust vector will support some weight, reducing the amount of lift needed to support the weight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-08-07T10:56:43.717" LastActivityDate="2017-08-07T10:56:43.717" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="15245" PostTypeId="2" ParentId="15243" CreationDate="2015-05-31T12:55:07.847" Score="10" Body="&lt;p&gt;When you say,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No power invested by the propeller goes into potential energy of the wing; the climb of the wing is done purely by lift.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;you're missing where the energy of the wing comes from. Lift isn't a magical power that creates potential energy out of nothing: it just turns airspeed (kinetic energy) into height (potential energy). In your example, the power invested by the propeller turns into kinetic energy of the whole cart, including the wing. That's how the energy gets from the propeller (or its fuel) into the potential energy of the wing. You need to use more thrust to drive the cart with the wing attached, than you would if you took the wing away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two ways to look at the forces produced during a climb. Remember that as a wing produces more lift, it also produces more &lt;em&gt;induced drag&lt;/em&gt;. That's why you need excess thrust, to generate the excess lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a certain power setting, you can fly level at a certain speed. If you pitch up, the wings will create excess lift, but also more drag. Even though some of your thrust is acting vertically, there isn't any excess thrust, because the drag is greater. You'll slow down, the lift will decrease, and you'll stop climbing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, you can keep the aircraft level, and add more thrust. This will increase your speed, which will also increase the lift from the wings. This in turn increases the induced drag, which will eventually balance the excess thrust at a new, higher airspeed. Because you've increased the lift by doing this, you'll climb, even though your wings are level. You can only do this because you added power in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I feel obliged to point out that you wouldn't usually climb like this: to get a better rate of climb, you'd generally add power and also pitch up, letting your airspeed decrease to the speed where the wings produce the most lift for the least drag.)&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-05-31T12:55:07.847" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15246" PostTypeId="2" ParentId="15239" CreationDate="2015-05-31T13:14:12.513" Score="2" Body="&lt;p&gt;The f-18 is a fly-by-wire aircraft. This means its automatic flight control system takes care of stabilizing the aircraft for cg changes, or other sudden forces (turbulence, bird strike, engine loss, etc). The controller keeps the aircraft in a balanced (&quot;trim&quot;) state and allows the pilot to maneuver the aircraft even in the presence of these sudden changes. Therefore the pilot would probably not feel the mass leaving the aircraft, and would not have to worry about which side the&#xA;Missile left (can be right or left wing).  &lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-05-31T13:14:12.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15247" PostTypeId="2" ParentId="15243" CreationDate="2015-05-31T13:27:08.293" Score="-5" Body="&lt;p&gt;The other answer (and the basic premise) are misleading. Aviation is a careful balance of just about everything, and you rarely get more of one without losing some of the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a rocket. No wings, and thus no lift. Sea level, 0m/s to orbit on 8 minutes. Everything done with a rather ridiculous amount of power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider an airship. Also no wings, but excess lift. Goes up all by itself. The engines are purely for maneuvering, if you remove them we usually call the thing a balloon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most ridiculous things I ever heard was a flight instructor who claimed that the throttle controls altitude and the elevator controls speed. I called complete BS on the statement and asked if he found himself flying toward some cumulo-granitus would he prefer to add power or yank back rather sharply on the controls?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What he was trying to get across was that in the extremely narrow regime of straight and level flight*, adjusting power will affect speed which affects lift, and the plane will eventually stabilize at a different altitude after a power adjustment. Adjusting pitch will change your speed almost immediately, but your altitude will change as well. You could arrange a demonstration of adjusting power and pitch simultaneously and having nothing else change, but that basically proves my point. If you want to slow down (for example, landing) do you leave the throttle at full and pull the stick all the way back? Of course not. It's a very delicate balance, and it's something pilots spend a lot of time learning. Or if you work for certain asian airlines you just have some very expensive computers handle it for you.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Yes, we spend a lot of time there, but consider how precise you need to be. A fraction of a degree, uncorrected, in any axis will result in you crashing before you run out of fuel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-05-31T13:27:08.293" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15248" PostTypeId="2" ParentId="15239" CreationDate="2015-05-31T13:34:33.463" Score="13" Body="&lt;p&gt;It's kind of a mix of the two. Flight controls on aircraft have what's known as &lt;em&gt;trim&lt;/em&gt;. All (or nearly all) airplanes have elevator trim; many also have rudder trim and aileron trim. The trimmer for each control is used to balance constant forces needed on that control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To take an example that's more widely applicable than launching missiles: when you increase power (to climb or to reach a faster airspeed), the airplane will have a tendency to pitch up, so you might find you need to push forward on the stick to maintain the right attitude. By moving the elevator trim forward, you eliminate the needed force, effectively changing the neutral position of the stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On early aircraft, the trim often worked by having springs connecting the control wires to a large lever. Working the lever pulls the spring in that direction, applying a force to the controls. On modern light aircraft, there is a &lt;em&gt;trim tab&lt;/em&gt; on each control surface. The trim tab is like a tiny control surface on the control surface. Moving the trim tab to one side or the other provides a force on it, replacing the force the pilot would provide through the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly-by-wire aircraft, such as military jets and large passenger airplanes, have electronic trim. Since the pilot doesn't have to put much force on the controls to work them anyway, trimming just resets the neutral position of the stick as you describe. Because it's electronic, there can be different ways to control it. Some aircraft still have small levers to set the trim; some have up/down buttons in reach of the stick (such as the Su-27); and yet others simply have a single button that trims to the current position of the controls (the A-10). As Mr Çetin points out, some very modern military jets take advantage of the possibility of computer control: the aircraft is aerodynamically unstable, but a flight control system manages keeping stable flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Returning to the particular case of the F-18, it doesn't re-trim itself. When heavy ordnance is launched, the aircraft will roll to one side as you suspect, and the pilot has to compensate with the stick and pedals. Once he has stablised the aircraft at the desired attitude and airspeed, he can adjust the trim using a hat switch on the stick.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-05-31T13:34:33.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15249" PostTypeId="2" ParentId="15242" CreationDate="2015-05-31T14:17:56.147" Score="7" Body="&lt;p&gt;I have no idea where the image comes from, but it seems that you have spotted an inconsistency/copy-paste typo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's remember that the heading is always measured w.r.t. the north, increases in a cloclwise fashion and indicated the direction the aircraft is flying to, as shown in the following figure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/coNeg.gif&quot; alt=&quot;VOR-Radial Demo&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.allstar.fiu.edu/aero/fltmidcomp.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.allstar.fiu.edu&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Rhumb line both East and West directions are shown both with arrows ($\rightarrow \;\; \leftarrow$) and with the initial headings ($90^o \;\; 270^o$)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Great Circle lines only the westerly arrows appear and only the starting headings from the West are correct. These seems to have been copied to the East side, but they should have also been augmented by $180^o$, i.e. as you were expecting, you should have $330^o$ for the northern hemisphere (in lieu of the $150^o$) and $210^o$ instead of $30^o$ for the southern.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="572" LastEditDate="2015-06-02T06:21:11.497" LastActivityDate="2015-06-02T06:21:11.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15250" PostTypeId="1" CreationDate="2015-05-31T15:22:07.133" Score="6" ViewCount="11281" Body="&lt;p&gt;I'm sure many of you are familiar with &quot;rudder hardover&quot;, where an aeroplane's rudder deflects to an extreme position - full left or full right. Many of you will be aware that such an event, caused by a faulty Power Control Unit, was implicated in the loss of United Airlines Flight 585 and USAir Flight 427. A rudder hardover was also involved in an incident on Eastwind Airlines Flight 517 and the investigation into that incident unravelled the mysteries around the loss of the two aforementioned flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is about the effects of a rudder hardover on flight - and how it led to the two crashes. I'm interested in what happens, aerodynamically, after the rudder has moved to its extreme position and the sequence of events which follows. It's obvious to me that a rudder hardover must be an extremely destabilising event. But I'd like a more detailed explanation of precisely what happens. What effects does it cause? What happens to the affected aeroplane and why might it crash?&lt;/p&gt;&#xA;" OwnerUserId="8067" LastEditorUserId="19" LastEditDate="2017-11-06T14:53:36.563" LastActivityDate="2018-07-17T19:13:54.813" Title="What happens after a rudder hardover?" Tags="&lt;aerodynamics&gt;&lt;accidents&gt;&lt;flight-controls&gt;&lt;rudder&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15251" PostTypeId="1" AcceptedAnswerId="15254" CreationDate="2015-05-31T16:23:12.343" Score="-3" ViewCount="9145" Body="&lt;p&gt;How can we determine the minimum power required for a propeller aircraft?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How can we determine the minimum power required at standard altitude of h=3km&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the maximum airspeed at standard sea level conditions ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;if :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wingspan = 10m &lt;/li&gt;&#xA;&lt;li&gt;Wing area =15m‌‌ Squared&lt;/li&gt;&#xA;&lt;li&gt;Mass = 1500 kg &lt;/li&gt;&#xA;&lt;li&gt;Power plant = one-piston engine of 230hp power available at sea level &lt;/li&gt;&#xA;&lt;li&gt;Parasite drag coefficient= 0.025 &lt;/li&gt;&#xA;&lt;li&gt;Oswald efficiency = 0.8 &lt;/li&gt;&#xA;&lt;li&gt;Air density at 3 km = 0.9093 kg/m&lt;sup&gt;3&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8698" LastEditorUserId="19" LastEditDate="2015-05-31T18:46:01.483" LastActivityDate="2015-06-01T16:12:27.973" Title="Basic aircraft performance: how can you calculate the required power?" Tags="&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2015-05-31T21:50:25.177" ContentLicense="CC BY-SA 3.0" />
  <row Id="15252" PostTypeId="2" ParentId="14888" CreationDate="2015-05-31T16:55:24.767" Score="4" Body="&lt;p&gt;Generally, a series of related aircraft uses the same wing: Take the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;A318, A319, A320 and A321&lt;/a&gt;: All use the same wing with the same airfoil, but the much lighter A318 can get away with single-slotted flaps while the heaviest, the A321, needs two flap sections for a double-slotted flap to tease out every bit of lift in order to keep the increase in take-off and approach speeds small. Since the flaps are the easiest part of the wing to adjust its lift capabilities to the needs of the aircraft, you will see a lot of variations in them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The leading edge devices don't show so much variation: Inboard, a &lt;a href=&quot;http://en.wikipedia.org/wiki/Krueger_flap&quot; rel=&quot;nofollow noreferrer&quot;&gt;Krüger flap&lt;/a&gt; is most common, and outboard a slat is used. While a slat will always have a slot between itself and the wing, a Krüger flap can be slotted or unslotted. When extended, both will show a very similar shape to the airflow, and only their movement is different: While the slat moves forward with a small downward rotation, the Krüger flap swings around a hinge close to the wing's leading edge. Both have either a fully retracted or a fully extended position, while trailing edge flaps can be set in steps to adjust them for moderate lift / low drag increase during take-off, or high lift / high drag for landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The complex hinge mechanism in your picture allows the Krüger flaps of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747&lt;/a&gt; to increase their camber when extended. This is actually unique among airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Krüger flap is the newest of them and was &lt;a href=&quot;http://en.wikipedia.org/wiki/Werner_Kr%C3%BCger&quot; rel=&quot;nofollow noreferrer&quot;&gt;invented in 1943&lt;/a&gt;. All patents on them expired long ago, and only individual details like the mechanism might be covered by patents today.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-03-15T20:02:29.707" LastActivityDate="2018-03-15T20:02:29.707" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15253" PostTypeId="2" ParentId="15222" CreationDate="2015-05-31T17:05:45.550" Score="9" Body="&lt;p&gt;For the regulatory portion of this question.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;14 CFR 121.318&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may operate an airplane with a seating capacity of more than 19 passengers unless it is equipped with a public address system which— &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Is capable of operation independent of the crewmember interphone system required by§ 121.319, except for handsets, headsets, microphones, selector switches, and signaling devices; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Is approved in accordance with§ 21.305 of this chapter; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Is accessible for immediate use from each of two flight crewmember stations in the pilot compartment; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) For each required floor-level passenger emergency exit which has an adjacent flight attendant seat, has a microphone which is readily accessible to the seated flight attendant, except that one microphone may serve more than one exit, provided the proximity of the exits allows unassisted verbal communication between seated flight attendants;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Is capable of operation within 10 seconds by a flight attendant at each of those stations in the passenger compartment from which its use is accessible; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Is audible at all passenger seats, lavatories, and flight attendant seats and work stations; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) For transport category airplanes manufactured on or after November 27, 1990, meets the requirements of§ 25.1423 of this chapter. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[Doc. No. 24995, 54 FR 43926, Oct. 27, 1989]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;14 CFR 25.1423&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A public address system required by this chapter must— &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Be powerable when the aircraft is in flight or stopped on the ground, after the shutdown or failure of all engines and auxiliary power units, or the disconnection or failure of all power sources dependent on their continued operation, for— &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A time duration of at least 10 minutes, including an aggregate time duration of at least 5 minutes of announcements made by flight and cabin crewmembers, considering all other loads which may remain powered by the same source when all other power sources are inoperative; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) An additional time duration in its standby state appropriate or required for any other loads that are powered by the same source and that are essential to safety of flight or required during emergency conditions. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Be capable of operation within 3 seconds from the time a microphone is removed from its stowage. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) &lt;strong&gt;Be intelligible&lt;/strong&gt; at all passenger seats, lavatories, and flight attendant seats and work stations. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Be designed so that no unused, unstowed microphone will render the system inoperative. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Be capable of functioning independently of any required crewmember interphone system. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Be accessible for immediate use from each of two flight crewmember stations in the pilot compartment. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) For each required floor-level passenger emergency exit which has an adjacent flight attendant seat, have a microphone which is readily accessible to the seated flight attendant, except that one microphone may serve more than one exit, provided the proximity of the exits allows unassisted verbal communication between seated flight attendants.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[Doc. No. 26003, 58 FR 45229, Aug. 26, 1993, as amended by Amdt.&#xA;  25-115, 69 FR 40527, July 2, 2004]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are systems in place to increase volume in certain instances, eg, on the 767 both engines running gives a 6 dB increase and O2 masks dropped gives an additional 3 dB gain in volume.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-01T15:56:38.430" LastActivityDate="2015-06-01T15:56:38.430" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15254" PostTypeId="2" ParentId="15251" CreationDate="2015-05-31T17:18:32.683" Score="5" Body="&lt;p&gt;Hints for your first question:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Power required is the product of drag and true airspeed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;$P_r = D\cdot V$&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;You can calculate drag as a function of airspeed. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;$D=\frac{1}{2}\rho V^2 S C_D$&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;The drag coefficient is the sum of the parasite drag coefficient and the induced drag coefficient. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;$C_D = C_{D,0} + C_{D,i}$&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;4&quot;&gt;&#xA;&lt;li&gt;The induced drag coefficient is a function of the lift coefficient, the wing geometry and the Oswald efficiency factor. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;$C_{D,i} = \frac{C_L^2}{\pi A e}$&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;5&quot;&gt;&#xA;&lt;li&gt;&#xA;The lift coefficient can be calculated as function of the speed, the density of the air, the weight of the aircraft and the wing area. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;$C_L = \frac{2 L}{\rho V^2 S}$ and for horizontal flight $L = W = mg$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Substituting yields:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P_r = \frac{1}{2}\rho V^3 S C_D = C_{D,0}\frac{1}{2}\rho V^3 S + \frac{2 W^2}{\pi A e \rho V S}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need to find the minimum of that function, which occurs when it's derivative equals zero. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the constants you need are given in the table, apart from the density at 3 km altitude, but I believe you have been given that as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same power formula derived above will also help to solve your second question.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-01T16:12:27.973" LastActivityDate="2015-06-01T16:12:27.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15255" PostTypeId="1" AcceptedAnswerId="15277" CreationDate="2015-05-31T17:33:53.447" Score="5" ViewCount="2135" Body="&lt;p&gt;In Seattle, it is common to request a transition over KSEA by asking for either the &quot;Bremerton Transition&quot; or &quot;Kent Transition&quot; (depending on what direction you're travelling). I learned these names from my CFI &amp;amp; have used them with no problem, but I've noticed that on the &lt;a href=&quot;http://skyvector.com/?ll=47.39603029911872,-122.28156360360246&amp;amp;chart=128&amp;amp;zoom=3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Seattle TAC&lt;/a&gt; they are referenced as Seahawk/Mariner Transition, which refer to which runway numbers to overfly rather than direction (personally, I've never heard these referred to on the radio).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, &quot;Bremerton&quot; transition refers to transitioning to Bremerton, but I'm curious if this is some agreed-upon lingo or just convention. Could I just as easily ask for a &quot;Port Orchard&quot; transition?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I were in an unfamiliar area, could I request a transition by referring to any location on the opposite side of the airspace? For example, if I wanted to transition PDX airspace could I request a &quot;Hillsboro Transition&quot;?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1nCQ7.jpg&quot; alt=&quot;Kent Transition over Seatac&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Sidenote:&lt;/strong&gt; I personally love transitioning KSEA. If you haven't done it &amp;amp; are in the area, pick a busy day and request a transition. It's pretty impressive to see the large commercial flights landing right below you. On a non-busy evening, I've heard rumor you can even request a stop\go on 16R&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3495" LastEditorUserId="3495" LastEditDate="2015-05-31T21:51:16.350" LastActivityDate="2015-06-01T12:34:34.250" Title="How should I refer to a transition through class B or class C airspace?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;class-b-airspace&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15257" PostTypeId="2" ParentId="15243" CreationDate="2015-05-31T18:20:16.507" Score="2" Body="&lt;p&gt;The simple answer is easy to demonstrate.&#xA;Start with an aircraft TRIMMED for straight and level flight.&#xA;For example 1000 feet, 100 mph, 1500 rpm fixed pitch prop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift = aircraft weight and thrust = aircraft drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now increase engine rpm by 150 rpm (10% more thrust), &#xA;which increases thrust.&#xA;The aircraft will for a moment accelerate, the increased airflow&#xA;over the wing and stabilizer increases lift and the aircraft will gain altitude. &#xA;In a few seconds the system will balance once again, the airspeed will return to the  trimmed 100 mph, and the excess thrust will show up as&#xA;climb rate. The aircraft will now be slightly pitched up, but the angle of attack remains constant since it is controlled by the stabilizer trim setting, which we did not touch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next roll the elevator trim forward, which will lower the nose a bit.&#xA;The airspeed will increase slightly and the climb rate will reduce.&#xA;When trimmed once again to straight and level flight the aircraft &#xA;rate of climb will be 0, the airspeed will be above 100 mph.&#xA;Now the extra thrust shows up as increased speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To continue the example, reduce the rpm back to the original &#xA;1500 rpm. leave the trim alone.&#xA;The aircraft should now show a decent rate, at the new slightly higher airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this was done without input from the control stick.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anytime the pilot maneuvers  the primary flight flight controls, &#xA;there is a nearly instant trade between angle of attack, speed, lift, drag, inertia, climb rate or decent. &#xA;Jerry S.&lt;/p&gt;&#xA;" OwnerUserId="8700" LastActivityDate="2015-05-31T18:20:16.507" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15258" PostTypeId="2" ParentId="12762" CreationDate="2015-05-31T18:28:58.897" Score="0" Body="&lt;p&gt;As Federico said, there is definitely a possibility of an acrobatic or stunt aeroplane, and the first thing that came to my mind when I saw this picture was an &lt;a href=&quot;https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTDrwIAbBWWOd4UdXXYRE3c3H1e81_D63I0y_5WLDp99Vt0k0cn&quot; rel=&quot;nofollow&quot;&gt;Extra 300S&lt;/a&gt;. The contrail looks to me like more of a smoke trail (Extra 300 series planes are usually equipped with smoke generators), as towards the beginning of the line the trail seems to be 'bunched up', or wavering. Also, a couple hundred feet (at best guess) from the turn, the line shifts, possibly as a result of wind shear and/or turbulence.&lt;/p&gt;&#xA;" OwnerUserId="8701" LastActivityDate="2015-05-31T18:28:58.897" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15259" PostTypeId="2" ParentId="15250" CreationDate="2015-05-31T18:29:59.853" Score="17" Body="&lt;p&gt;With a fully deflected rudder the airplane will fly with substantial &lt;a href=&quot;http://en.wikipedia.org/wiki/Slip_(aerodynamics)&quot;&gt;sideslip&lt;/a&gt;, and by dropping the windward wing it can be held on a straight course. This is usually done intentionally with gliders and light aircraft when they want to lose altitude quickly, because the high sideslip angle will increase drag substantially. If $\zeta$ is your rudder deflection angle, the slip will normally have a sideslip angle $\beta$ of between -$0.5\cdot\zeta$ and -$\zeta$, depending on the details of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the hardover happens at high speed, the resulting aerodynamic forces will certainly overstress the fuselage and tail structure, and the aircraft will &lt;a href=&quot;http://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot;&gt;break apart and crash&lt;/a&gt;. No amount of pilot skill can prevent this!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft survives the hardover incident, the best the pilot can hope for is a controlled crash: The sideslip angle will cause the landing gear to be torn off, and the dropped windward wing will provoke a &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_loop_(aviation)&quot;&gt;ground loop&lt;/a&gt; - if the pilot tries to level the wings during the flare, the resulting yawing motion will ground loop the plane in the other direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I once had the chance to fly the prototype of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Swift_S-1&quot;&gt;Swift S-1&lt;/a&gt;, an excellent Polish aerobatic glider. During one maneuver my left pedal got stuck, and I saw myself already sideslipping the plane into the ground. In the remaining minutes I tried to get the pedals unstuck and got lucky, ending the flight with an uneventful landing. Afterwards, I found out that the pedal mechanism had caught the wire from the battery, and my maneuvering had freed it up again. This was the closest I ever came to land with a rudder hardover, and I am not eager to ever try this out for real.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-05-31T18:29:59.853" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15260" PostTypeId="2" ParentId="15230" CreationDate="2015-05-31T19:54:11.273" Score="2" Body="&lt;p&gt;There is always a disruption (i.e a &lt;em&gt;perturbation&lt;/em&gt;) in the air by a object traveling through it. Each one can be seen as a sphere (or circle in a 2D diagram). At speeds below Mach 1, these disruptions never converge, i.e. the spheres never meet. However, at any speed beyond Mach 1, they no longer travel faster than the aircraft and get 'left behind'. In this case the sides of each expanding sphere converge along a cone shape into a powerful shock wave that we perceive with as a bang.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rDMBl.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt; &lt;a href=&quot;https://hronrad.files.wordpress.com/2012/04/supersonic.jpg?w=876&amp;amp;h=350&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The only difference is that as the aircraft becomes faster, the angle of the sonic boom in regard to the direction vector of the aircraft decreases: The cone becomes more acute as the spacing between each imaginary sphere becomes greater. You can never generate more than than one sonic boom, since it's a one-time transition. (On a more complicated note, some vehicles, included the space shuttle, pull of two sonic booms by disrupting the air twice)&lt;/p&gt;&#xA;&lt;p&gt;You would perceive the same thing with a boat- above a certain speed you would generate a wake going outwards in two directions to the side behind you.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YAedI.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&amp;quot;Fjordn surface wave boat&amp;quot; by Edmont - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-05-31T21:37:03.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15261" PostTypeId="2" ParentId="8318" CreationDate="2015-05-31T20:28:10.147" Score="2" Body="&lt;p&gt;I have been a pilot for 10 years you learn on a prop plane mostly because of the speed. The faster your going the faster you need to think and react to not get &quot;behind the plane&quot; I would also have to say that in my opinion prop planes are safer less to wrong slower and fly at a lower altitude. And in addition to that in case you crash it less cost for flight school to replace&lt;/p&gt;&#xA;" OwnerUserId="8704" LastActivityDate="2015-05-31T20:28:10.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15262" PostTypeId="2" ParentId="15234" CreationDate="2015-05-31T21:53:00.013" Score="32" Body="&lt;p&gt;As far as I read in various documents about A320 and remember them correctly:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three systems handling different parts of the primary flight control:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ELAC (elevator &amp;amp; aileron computer) controls pitch with elevators+trim and roll with ailerons.&lt;/li&gt;&#xA;&lt;li&gt;SEC (spoiler &amp;amp; elevator computer) controls roll with spoilers and if ELACs fail, pitch with elevators+trim.&lt;/li&gt;&#xA;&lt;li&gt;FAC (flight augmentation computer) implements yaw damper. Its command is &lt;em&gt;added&lt;/em&gt; to the rudder command. In A320 rudder pedals have direct mechanical (hydraulic) link.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The ELAC and FAC are composed of two identical units each, the SEC of three identical units (but only two of the units are used as backup for ELAC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each unit is composed of two dissimilar computer boards. One used i386 CPU, the other m86k CPU and each has independently developed software (to minimize risk of the same software bug in both).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the boards in each pair calculates the output and the other one verifies it. If the verification fails, that unit declares fault and disconnects. This is the primary way of detecting faults.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found no reference to comparing outputs of the identical units. Except for spoiler control there are only two output and the check board is more reliable way of detecting faults anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the FAC fails, the aircraft won't maintain coordinated flight well and will tend to dutch roll, but pilots can compensate it with rudder input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the SEC fails, the ELAC can handle control alone. Just spoilers won't be available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the ELAC fails, the SEC can take over too. Turning with spoilers may cause some more drag, but not a big problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both ELAC and SEC fail, the pitch trim wheels have direct mechanical (hydraulic) link and roll can be controlled by rudder by taking advantage of the yaw stability. I don't think it was ever needed in practice. Note, that is for A320 family; which controls are available in case of failure of all flight computers is different in each Airbus type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for data input, there are three ADIRUs (air data and inertial reference unit) and each flight computer takes input from all three and compares them. It needs two matching (similar within some limit) values to consider it trustworthy. If either more than one unit fails or no two agree, the flight computers degrade to &lt;em&gt;alternate law&lt;/em&gt; or &lt;em&gt;direct law&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In alternate law, the system stops providing alpha protection (stall), overspeed protection and, depending on what failed, other flight envelope protection (there are two kinds, with different protections lost).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In direct law it reverts to directly mapping the stick position to control surface position similar to mechanical controls. But most faults only result in alternate law except if all inertial references were lost (that would be very difficult to handle as it would mean unreliable attitude indicators too, but I don't think that ever happened either; the inertial systems are very reliable).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternate or direct law can also be entered if some control surface (or its actuator) fails and somewhere in the computer failure sequence, but I don't remember the exact condition (FACs calculate the limits, so if FACs fail, it will certainly degrade).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="27586" LastEditDate="2017-12-14T08:57:54.223" LastActivityDate="2017-12-14T08:57:54.223" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15264" PostTypeId="2" ParentId="15230" CreationDate="2015-06-01T03:25:50.580" Score="4" Body="&lt;p&gt;Your question is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why is it that the sonic boom only occurs at the moment the plane crosses Mach 1?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer is: &lt;strong&gt;It doesn't&lt;/strong&gt;. Sonic boom first occurs when the plane crosses Mach 1 and the plane continues producing sonic boom as long as the speed stays above Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another part of your question is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How come sonic booms only occur once?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the answer is: &lt;strong&gt;because the plane flew over you once&lt;/strong&gt;. If the plane were to turn around and fly over you a second time you'd hear two sonic booms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you hear a sonic boom it doesn't mean that that boom was generated at Mach 1. It only means that the boom was generated at speeds equal to or greater than Mach 1. For example, a plane travelling at Mach 3 would still produce a sonic boom but you'd still only hear it once because the &quot;boom&quot; would only reach your ear once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To understand this you need to understand what a sonic boom is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Various parts of the airplane generate sound. Form the roar of the jet engines to the whistle of the skin of the aircraft moving through the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When travelling at normal subsonic speed. These sounds travel normally through the air and what you hear is a continuous sound of an airplane flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When travelling at or faster than the speed of sound, all these sounds arrive at your ear simultaneously. That is to say, if normally you'd be able to hear a plane passing overhead over a period of 10 seconds (for example) then at supersonic speeds all those 10 seconds of sounds (engine roar, woosh of the wings etc.) arrive at your ear at the same moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since all the sounds you'd ever hear from the airplane arrive at the same time, the result is a very loud boom (all the 10 seconds or more of sound added together).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's why you only hear it once typically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are exceptions though. If the plane is long enough, and the nose and tail generate loud sounds, it is possible to experience a double sonic boom caused by the tail generating a second boom. But generally, even a very long plane like the 747 or A380 (or Concorde) would take only a very tiny fraction of a second to travel the length of their body at supersonic speeds. You'd probably need a plane a mile long to experience a proper double boom.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-06-01T03:25:50.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15265" PostTypeId="2" ParentId="15250" CreationDate="2015-06-01T04:23:08.223" Score="5" Body="&lt;p&gt;Hardover of a control surface basically means that it has become jammed against a mechanical stop; think of having a poltergeist in your plane, applying full rudder (or aileron, or elevator) one way or another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the rudder, it indeed will cause a severe yaw and roll with the resulting sideslip.  Dealing with this requires a hefty helping of opposing aileron control (and spoileron, if your plane has that); this creates a forward slip, which keeps the plane on course at the cost of increased sink, which requires more pitch and power to overcome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most jets, this is hard on the crew, but doable: American Eagle 4649's crew shot an ILS into Bangor in blowing snow with their Embraer 135's rudder jammed full right, landing safely.  However, in the 737's case, the rudder has so much low-speed authority that below a certain airspeed, there isn't enough aileron/spoileron roll authority to overcome the adverse roll from a hardover rudder.  Worse yet, the 737 PCU problem not only sent the rudder hard over, it caused a &lt;em&gt;reversal&lt;/em&gt; to occur -- the pilots stepped on the pedal they thought would make things better, and the rudder problem got worse, confusing the absolute snot out of them.  You might be able to get out of it with differential power, provided it was applied soon enough to counter the roll before you went over on a wingtip and down...&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-06-01T04:23:08.223" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15266" PostTypeId="2" ParentId="15243" CreationDate="2015-06-01T08:07:14.240" Score="7" Body="&lt;p&gt;I sort of feel that the rest of the answers are unnecessarily complex, given how simple the fundamentals here are:&lt;/p&gt;&#xA;&lt;h3&gt;Momentum&lt;/h3&gt;&#xA;&lt;p&gt;Question: Is it necessary that L&amp;gt;m.g (or as you put it, an excess of lift) in order to climb?&lt;/p&gt;&#xA;&lt;p&gt;Answer: No, at least not a sustained excess of lift. Newton's Laws state that an object in motion will remain in that state unless a force acts upon it. A force imbalance is required to set the aircraft into a climb, but once this has been achieved the forces can be balanced and the aircraft will continue to climb. As such, an excess of lift is not a condition required for an aircraft to sustain a climb.&lt;/p&gt;&#xA;&lt;h3&gt;Energy&lt;/h3&gt;&#xA;&lt;p&gt;Question: Is it necessary that we add energy to the system (in the form of increasing our power output) in order to climb?&lt;/p&gt;&#xA;&lt;p&gt;Answer: Yes, if energy is conserved then in order to gain altitude (and by extension gravitational potential energy), we must add energy. We could add no energy, not increase the power output of our engines, and simply pull up, increasing AoA but also drag, and we would climb for a short time as we trade kinetic energy for gravitational potential energy, however we would find that our aircraft quickly slows and we are required to dive to below our original altitude to return to steady level flight.&lt;/p&gt;&#xA;&lt;p&gt;Hence a power excess is necessary for climb, but a sustained lift excess is not.&lt;/p&gt;&#xA;" OwnerUserId="7979" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-01T08:07:14.240" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15267" PostTypeId="2" ParentId="15243" CreationDate="2015-06-01T08:32:01.260" Score="1" Body="&lt;p&gt;The above answers beautifully explain the theoretical solution to your problem, but since you haven't accepted any one of them as of now, i'd be illustrating the solution numerically.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Lets assume that your cart is moving with a constant velocity of 'v'&#xA;&#xA;Then, K.E. = 1/2 (mv^2)&#xA;D = 1/2((density)(v^2)S(Cd))&#xA;and total energy E = K.E. + D*distance (Assuming frictionless interaction of surfaces everywhere)&#xA;&#xA;now, Cd = Cd0 + K(Cl)^2&#xA;distance = v*t&#xA;so T.E. = 1/2(v^2)(m + (density)SVt(Cd0 + K(Cl)^2))&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Here it can be seen that total energy is being used for&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The kinetic energy part of the Cart&lt;/li&gt;&#xA;&lt;li&gt;The coefficient of lift part of the Cart's wing&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The coefficient of lift part is hence responsible for the energy use3d up in lifting the wing upwards and hence the whole system obeys conservation of energy&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-01T08:32:01.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15268" PostTypeId="1" AcceptedAnswerId="15279" CreationDate="2015-06-01T09:04:52.420" Score="10" ViewCount="11693" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/15262/2176&quot;&gt;the very interesting answer&lt;/a&gt; from Jan Hudec to a question about the various flight control computers on Airbus planes, two different means to trim the aircraft are mentioned: The stabiliser and the elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does this work in practice? How is the aircraft trimmed in flight, both as seen from the flight deck (i.e., the user interface to the pilots) and as actual input to the control surfaces?&lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-06-04T07:47:54.667" Title="How does trim work on an A320?" Tags="&lt;flight-controls&gt;&lt;airbus-a320&gt;&lt;trim&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15269" PostTypeId="1" AcceptedAnswerId="15272" CreationDate="2015-06-01T09:16:14.773" Score="27" ViewCount="105963" Body="&lt;p&gt;Why do some fighter jets have two pilots, while some have only one?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the newer fighter jets such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Dassault_Rafale&quot;&gt;Dassault Rafale&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot;&gt;Eurofighter typhoon&lt;/a&gt; etc. are mostly with single-seat, but two-seat models of these jets are also available.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="1696" LastEditDate="2018-04-22T18:43:00.967" LastActivityDate="2018-11-17T15:10:07.610" Title="Why do some fighter jets have two pilots while others have only one?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;cockpit&gt;&lt;jet&gt;" AnswerCount="9" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15270" PostTypeId="2" ParentId="15242" CreationDate="2015-06-01T09:20:31.923" Score="1" Body="&lt;p&gt;After some thoughts and ask around, finally figure out the answer to this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be depicted by the image below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7BD5v.png&quot; alt=&quot;3D representation of rule&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: Own Work - Author: tipsywacky)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying great circle, the angle is measured against the meridian. If it starts from left to right, it will be 30 degree increasing and then reach 150 on the other side and vice versa. Drawing it out on the orange is the key.&lt;/p&gt;&#xA;" OwnerUserId="8696" LastEditorUserId="572" LastEditDate="2015-06-02T06:02:12.657" LastActivityDate="2015-06-02T06:02:12.657" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15271" PostTypeId="1" CreationDate="2015-06-01T09:31:32.197" Score="3" ViewCount="1494" Body="&lt;p&gt;What is the parasite drag or C&lt;sub&gt;D,0&lt;/sub&gt; for the Airbus A320?&#xA;How do we calculate C&lt;sub&gt;D&lt;/sub&gt;? Is it correct to use C&lt;sub&gt;D&lt;/sub&gt; = C&lt;sub&gt;D,0&lt;/sub&gt; + ( C&lt;sub&gt;L&lt;/sub&gt;&lt;sup&gt;2&lt;/sup&gt;)/$\pi$AR&lt;/p&gt;&#xA;" OwnerUserId="8709" LastEditorUserId="19" LastEditDate="2015-06-01T09:39:08.723" LastActivityDate="2015-06-01T09:40:38.350" Title="What is the parasite drag for Airbus A320?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15272" PostTypeId="2" ParentId="15269" CreationDate="2015-06-01T09:32:04.340" Score="21" Body="&lt;p&gt;Speaking of fighters in their basic role, there are 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interception and escort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A single seat fighter would be superior in both scenarios because the space occupied by the second seater, plus the life support systems double the weight which can be put to fuel, countermeasures or weapons, and the extra weight and space will affect handling in air to air combat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the role is ground attack, 2 seat versions can be an advantage, such as SAM suppression mission, bombing and other types of strikes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the above applies to modern aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Previously, say the 1970s and before, 2 seat fighters were sometimes necessary due to the technology available at that time. The F-4 and F-14 for example, the 2nd seater operated the radar because the pilot really couldn't keep his head in the cockpit when engaging multiple enemy contacts or when the fight was close in. Head up displays weren't available so the aircraft systems available to the pilot by necessity was kept limited in order to limit pilot overload. &lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-01T09:32:04.340" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15273" PostTypeId="2" ParentId="15271" CreationDate="2015-06-01T09:40:38.350" Score="2" Body="&lt;p&gt;For numerical usage (in some question) you can use the above formula, but for exact drag (and lift) calculation, the industry standard is to use Computer Solvers to compute this drag because of the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The formula used above is correct but the value of Cd varies for every point on the wing, as things like wing twist, sweep back, wing tip sharklets contribute to a different Cd throughout the wing.&lt;/li&gt;&#xA;&lt;li&gt;Other effects like drag due to fuselage etc can not be calculated by using a generalized equation for the whole plane, as usually local Cd for every point on the airplane surface are known.&lt;/li&gt;&#xA;&lt;li&gt;Application of force on the surface of an airplane (Lift/Drag force) causes deformation in the geometry of the surface and this leads to recursive change in the value of Cd/Cl, which hence needs further set of calculation to again arrive at a value of Cd from the Solver.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For approximate usage though an averaged out Cd, Cd0 and AR if known, then the above formula can be applied to arrive at the results.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-01T09:40:38.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15274" PostTypeId="2" ParentId="15269" CreationDate="2015-06-01T09:45:09.087" Score="6" Body="&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/15272/572&quot;&gt;Vivian jeet Singh Sudan's answer&lt;/a&gt;, most tactical aircraft also have training versions, which are indeed two-seaters with dual flight controls with the instructor sitting in the back. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two-seat Eurofighters, Rafales, versions B &amp;amp; D of the Eagle and Fighting Falcon, anything from MiG or Sukhoi with a -UB suffix, etc. are all examples of this. That's not to say that they can't be operated in a pilot + weapons officer configuration (or single-pilot for that matter) and they normally retain full combat capability, but they're primarily intended for initial training, checkrides, and the like.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-06-01T12:32:28.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15275" PostTypeId="1" AcceptedAnswerId="15283" CreationDate="2015-06-01T09:54:01.413" Score="5" ViewCount="862" Body="&lt;p&gt;Fluid Structure Interaction (FSI) causes an  aeroplane’s geometry to change and hence the forces on the different surfaces of an aeroplane become different than the forces expected according to initial calculation.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is this Fluid Structure Interaction considered while calculating&#xA;forces (and hence the final design) of aircraft while finalizing&#xA;the designs for aircraft?&lt;/li&gt;&#xA;&lt;li&gt;If it is considered, what are the available software packages which could be used to analyse this?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-02T08:57:16.770" LastActivityDate="2015-06-02T08:57:16.770" Title="Is Fluid Structure Interaction considered in aircraft design?" Tags="&lt;aircraft-design&gt;&lt;aeroelasticity&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15276" PostTypeId="2" ParentId="15275" CreationDate="2015-06-01T11:13:17.047" Score="3" Body="&lt;p&gt;Aero-elasticity is indeed considered in design and certification of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One software package that I know is capable of aero-elasticity computations is &lt;a href=&quot;https://www.youtube.com/watch?v=mgPIaJylXk4&quot; rel=&quot;nofollow&quot;&gt;NASTRAN&lt;/a&gt; / PATRAN. No doubt there will be others.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-01T11:13:17.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15277" PostTypeId="2" ParentId="15255" CreationDate="2015-06-01T11:43:49.463" Score="4" Body="&lt;p&gt;You'll sometimes get radio phraseology different from what is published on charts either due to some holdover from now-superseded procedures (bad form, but it happens) or because of Letters-Of-Understanding that exist between the local Air Traffic Facility and certain operators or interest groups/associations, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're going someplace new and want to use a published VFR Transition through class Bravo, the best way to go about it is to use the nomenclature on the charts in order to reduce confusion. Otherwise, it is also acceptable to simply request a VFR clearance through the airspace in a general direction of travel. Depending on your altitude, position and direction of travel, as well as traffic load and any airports you need to get around, ATC will vector you through or around the class Bravo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial call follows the standard procedures outlined in the AIM and the Pilot/Controller Glossary. For example, starting out NE of Orlando class Bravo and asking for a transition to the SW, could be something like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Orlando Approach, Husky 123 Alpha Bravo Charlie, 35 northeast of the ORL VOR at 4500, request VFR transition to the Southwest through class Bravo.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're near a local landmark, you could use it as a reference to help the controller find your aircraft more easily:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Orlando Approach, Husky 123 Alpha Bravo Charlie, 2 northeast of Lake Ashby at 4500, request VFR transition to the Southwest through class Bravo.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, if a VFR Transition or flyway is available, the preference is to have VFR traffic use it in order to lighten the controllers' workload, but if you don't have the charts, or would rather not do that for some reason or the other, you don't have to. Just follow the general procedures for transitioning through class Bravo and they'll do their best to accommodate you.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-06-01T12:34:34.250" LastActivityDate="2015-06-01T12:34:34.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15278" PostTypeId="2" ParentId="15269" CreationDate="2015-06-01T12:06:28.177" Score="29" Body="&lt;p&gt;All &lt;strong&gt;&lt;em&gt;fighter&lt;/em&gt;&lt;/strong&gt; aircraft have &lt;strong&gt;one pilot&lt;/strong&gt;, though some have &lt;strong&gt;two crew members&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The backseat crew member is not a pilot, but often either a &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/an-elite-f-14-airman-explains-why-the-tomcat-was-so-imp-1610043625&quot;&gt;Radar Intercept Officer&lt;/a&gt; (US Navy), &lt;a href=&quot;http://en.wikipedia.org/wiki/Navigator&quot;&gt;Navigator&lt;/a&gt;/&lt;a href=&quot;http://en.wikipedia.org/wiki/Weapon_systems_officer&quot;&gt;Weapon Systems Officer&lt;/a&gt; (USAF, IDF), or &lt;a href=&quot;http://en.wikipedia.org/wiki/Flight_instructor&quot;&gt;Flight instructor&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Though not fighter aircraft&lt;/em&gt;, I believe that the &lt;strong&gt;SR-71&lt;/strong&gt; backseat crewmember operated the reconnaissance equipment as the single crewmember on the U2 was often overloaded with keeping the thing in the coffin corner &lt;em&gt;and&lt;/em&gt; operating the reconnaissance equipment. Jan and Habu mention in the comments that the SR-71 backseat crew member was also the navigator and operated the &lt;a href=&quot;http://en.wikipedia.org/wiki/Electronic_countermeasure&quot;&gt;ECM&lt;/a&gt; equipment. Additional comments mention that the &lt;strong&gt;B-1B&lt;/strong&gt; consists of four crew members: two pilots, an OSO (offensive systems operator), and a DSO (defensive systems operator). The &lt;strong&gt;B2&lt;/strong&gt;  has two crew members, both pilots, and while one is flying the other can rest, navigate, or operate the weapons system. &lt;em&gt;Thanks to Jan, Habu, and Joel for comments and clarifications!&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="354" LastEditDate="2015-07-13T19:06:07.643" LastActivityDate="2015-07-13T19:06:07.643" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="15279" PostTypeId="2" ParentId="15268" CreationDate="2015-06-01T13:07:19.657" Score="9" Body="&lt;p&gt;The faster an aircraft is, the wider range of elevator deflections it needs. And so do aircraft with large change of weight (amount of fuel used) during flight. However larger elevator deflection causes higher drag. It is more efficient to move the whole horizontal stabilizer instead. Therefore jet aircraft generally have the forward part of the horizontal stabilizer movable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it would be possible to simply have the whole stabilizer move. And supersonic aircraft generally have just that. It is called &lt;a href=&quot;http://en.wikipedia.org/wiki/Stabilator&quot;&gt;stabilators&lt;/a&gt;. However having the stabilizer split lends itself to elegant solution for trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This takes advantage of the fact, that the aerodynamic forces tend to put the elevator in the position of lowest drag almost straight (slightly bent in direction of less lift) behind the forward part. So when the forward part is moved, the lift changes without changing the force on the elevator. So the elevator is used for the small adjustments where the elevator is intended to return to the neutral position, which the aerodynamic forces help with, and the stabilizer is used to trim for current airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft with mechanical controls, the elevator force (or a fraction of it via power drive) acts directly back on the control column and the pilot can feel it, while the horizontal stabilizer is actuated via mechanism that holds selected position (may be electrical with jack-screw like on DC-9 or hydraulic, but with no feedback) and connected to the trim, which is usually pair of large wheels on the sides of the centre console.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in Airbus A320 and all newer models the side-stick does not have mechanical link and the pilot does not feel the force on the elevator anyway. In normal law, the ELACs automaically adjust the elevator and stabilizer so that with side-stick in neutral position, the aircraft maintains 1 G vertical acceleration and therefore straight flight (at any flight path angle). Since the trim wheel does have direct mechanical link, it turns as the ELACs (or SECs) adjust trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the distinction between elevator and trim is still useful in case of failure. When the system degrades into direct law, the side-stick position corresponds to the elevator deflection and the trim wheel position corresponds to the stabilizer position. Since the side-stick still returns to neutral position, the distinction of using the elevator for momentary adjustments and trim to balance the aircraft to fly (approximately) straight at current speed holds (just because the side-stick is spring-loaded, the force needed to deflect it does not increase with speed as it does for mechanical controls).&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-01T13:07:19.657" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15280" PostTypeId="2" ParentId="15269" CreationDate="2015-06-01T15:26:13.950" Score="3" Body="&lt;p&gt;The primary reason any fighter aircraft would be designed for two crew members is work load.  As avionics, sensors and weapon systems advance they become easier for a single pilot to operate, which is why far fewer fighter aircraft have two crew members now than in the past.  &lt;/p&gt;&#xA;" OwnerUserId="7752" LastActivityDate="2015-06-01T15:26:13.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15281" PostTypeId="2" ParentId="15222" CreationDate="2015-06-01T15:40:51.660" Score="7" Body="&lt;p&gt;The microphones used in aviation headsets are simple electret microphones, with high vocal clarity but low response at high frequencies.  They provide a quality similar to standard telephone service.  Since the pilots use these microphones to speak on the internal PA, there's no reason to install a high fidelity PA fed by a low fidelity microphone.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PA's purpose is clear transmission of information, same as the radio.  High voice quality is a very low priority, and it's also difficult to control without a custom microphone setup for each individual pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that your basic assumption is that a higher fidelity system would improve the passengers' ability to understand the crew.  This is not actually true.  Low-bandwidth systems such as telephone operate on the principle that speech can be understood as well (and sometimes better) with its high frequency components removed.  This offers the additional advantage of requiring lower channel capacity per user of the system (in both telephone and radio comms).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high quality audio address system, such as that used by a radio DJ, requires a quiet environment, a high-quality, highly-sensitive microphone, and a speaker with a consistent voice, who maintains a consistent distance from the microphone.  None of these are practical in an aircraft cockpit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A slightly lower-level system, such as that used by a speaker on a stage, would use a microphone on an earpiece in a similar location to that of the pilot's microphone.  However these are condenser microphones, which are non-directional and highly sensitive.  Such a microphone would be overwhelmed by background noise in an aircraft cockpit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both the radio setting and that of the speaker on a stage, there is also a dedicated sound engineer who is monitoring the level of the speaker and making adjustments to the microphone output.  Equalizers, compressors, and reverb are also employed among other effects to improve the quality of the speaker's voice.    &lt;/p&gt;&#xA;" OwnerUserId="7752" LastEditorUserId="7752" LastEditDate="2015-06-01T15:47:36.650" LastActivityDate="2015-06-01T15:47:36.650" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15282" PostTypeId="2" ParentId="15275" CreationDate="2015-06-01T16:29:41.740" Score="6" Body="&lt;p&gt;Just one example: Good designers put the aileron pushrods &lt;strong&gt;away&lt;/strong&gt; from the elastic axis of the wing to enable the deformation of the wing to create a damping deflection of the ailerons. This is especially helpful for high aspect ratio wings:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3nXm1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the wing flexes, the pushrod will not be compressed, so will become relatively longer than the surrounding wing structure. This will create a negative aileron deflection which works against the lift force which flexes the wing in the first place. Doing this is particularly helpful in damping wing flutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the engineers make sure that every aircraft component works as intended even when the structure is deformed. Another example: To compensate for differences in the thermal expansion of different components, pushrods in glass fiber fuselages have two halves, connected by a pivoting lever, so that changes in their length will compensate.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-06-01T16:29:41.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15283" PostTypeId="2" ParentId="15275" CreationDate="2015-06-01T18:00:11.970" Score="4" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;deflections must be considered, if relevant in the force (pressure) distributions and if relevant for the aerodynamic and structural design of the aircraft. In addition to that, flutter, buffeting and other fluid-structure (aeroelasticity) effects must be considered as well. In addition to that, when relevant, aero-servo-elasticity (the dynamic behavior of the aero-structure AND the response of the control system to that behavior) is also considered. This becomes a critical analysis for some designs (like, high aspect ratio or highly flexible aircraft), and has historical stories (good, funny or bad consequences).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For static aeroelasticity, you can go iteratively by hand or by using simple calculations. But especially for dynamic cases, if you do not go into simplified approaches, it generally requires Nastran or other off-the-shelf of home-developed FSI capable solvers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This page has a picture showing the relationship between flight related phenomena: &lt;a href=&quot;http://www3.imperial.ac.uk/aeroelastics/projects/flexibleaircraft&quot; rel=&quot;nofollow&quot;&gt;http://www3.imperial.ac.uk/aeroelastics/projects/flexibleaircraft&lt;/a&gt;&#xA;(aeroelasticity , flight mechanics, flexible body dynamics)&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-01T18:00:11.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15285" PostTypeId="2" ParentId="15269" CreationDate="2015-06-01T19:51:05.093" Score="1" Body="&lt;p&gt;Two-pilot versions of almost all military planes exist (including the SR-71 until its retirement). They are for training pilots to fly them.&lt;/p&gt;&#xA;" OwnerUserId="5711" LastActivityDate="2015-06-01T19:51:05.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15286" PostTypeId="1" AcceptedAnswerId="15290" CreationDate="2015-06-01T21:31:27.517" Score="19" ViewCount="1826" Body="&lt;p&gt;I was flying the &lt;a href=&quot;http://155.178.201.160/d-tpp/1506/05677R33.PDF&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) RWY 33&lt;/a&gt; approach into KFNL during instrument meteorological conditions.  The plate identifies a &lt;strong&gt;non-standard&lt;/strong&gt; 6 NM racetrack reversal at IMOMY:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f9DvK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Denver approach cleared me direct to IMOMY.  I was approaching from the Southwest, but NOT from HYGEN. Thus, I began a circuit around the depicted procedural track. I was cleared for the approach and approved to change to advisory frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At about 4 NM outbound, ATC contacted me* and asked when I planned to turn inbound.  I advised that I could begin inbound immediately, which they then asked (not cleared) me to do, in order to avoid encroaching on departing traffic from KDEN.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During VFR practice approaches (not under ATC), we always shortened the course reversal on this particular approach to save time. When doing the real thing, it was always my understanding that the depicted track had to be flown EXACTLY as published.  Per the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;noreferrer&quot;&gt;FAA Instrument Procedures Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A holding pattern in lieu of procedure turn may be specified for course reversal in some procedures. In such cases, the holding pattern is established over an intermediate fix or a [final approach fix]. The holding pattern distance or time specified in the profile view must be observed. For a hold-in-lieu-of PT, the holding pattern direction must be flown as depicted and the specified leg length/timing must not be exceeded. (Page 4-53)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now, I was also taught that if you have to perform a teardrop or parallel entry, that completed your reversal and no circuits are necessary:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The holding pattern maneuver is completed when the aircraft is&#xA;  established on the inbound course after executing the appropriate&#xA;  entry. (Ibid.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question 1:&lt;/strong&gt; Was it appropriate for me to attempt to fly the 6NM circuit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question 2:&lt;/strong&gt; Am I allowed to choose an arbitrary leg distance (or time), as long as the 6NM limit is not exceeded?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*I was already switched over to the CTAF, but still monitoring approach control on the second radio which I always do &lt;em&gt;just in case&lt;/em&gt;. Something I picked up from my flight instructor who flew larger planes for a living...&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-06-01T21:38:43.063" LastActivityDate="2020-11-07T16:25:56.647" Title="During instrument approach, is an abbreviated racetrack course reversal allowed?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15287" PostTypeId="1" CreationDate="2015-06-01T21:57:20.023" Score="7" ViewCount="141" Body="&lt;p&gt;The Atlanta TAC has a note that says &quot;See back of this chart for procedural information within the Atlanta Class B Airspace&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dtQT1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I don't have a physical copy of the TAC - because I'm using a flight planning app, for example - where else can I find the information?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-02T00:13:17.567" Title="Where can I find the information from the back of a TAC if I don't have a physical copy?" Tags="&lt;usa&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15288" PostTypeId="2" ParentId="15287" CreationDate="2015-06-01T22:50:35.680" Score="2" Body="&lt;p&gt;If you are using &lt;a href=&quot;https://www.foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;Fore Flight&lt;/a&gt; you can &lt;a href=&quot;https://support.foreflight.com/hc/en-us/articles/203309619-How-do-I-view-a-chart-legend-&quot; rel=&quot;nofollow&quot;&gt;Turn On Legends&lt;/a&gt; which will show you the legend information for the map. You may also be able to download the information somewhere else in the application. It will help if you inform us of which app you are using. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://ipadpilotnews.com/2012/06/how-to-use-documents-in-foreflight-mobile/&quot; rel=&quot;nofollow&quot;&gt;documents&lt;/a&gt; section of &lt;a href=&quot;https://www.foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;Fore Flight&lt;/a&gt; there are some other Atlanta area documents. Im not sure what the back of the cart looks like so I'm not sure if any of them are correct but there is the Atlanta FLY chart and the Atlanta Class B diagram.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-01T23:08:08.580" LastActivityDate="2015-06-01T23:08:08.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15290" PostTypeId="2" ParentId="15286" CreationDate="2015-06-02T01:08:50.077" Score="13" Body="&lt;p&gt;Unless you were &quot;cleared straight-in&quot; for the approach, when IMOMY is your IAF (as it was in this case) you are &lt;strong&gt;required&lt;/strong&gt; to fly the course reversal, even if you can execute a direct entry. This is because the approach does not have terminal arrival areas labeled NoPT. So, &lt;strong&gt;yes, it was appropriate to fly the 6nm reversal&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, &lt;strong&gt;no&lt;/strong&gt;, you cannot choose a different course reversal, even a shorter distance hold. When a hold is depicted in lieu of a procedure turn (HILO) you are required to fly the hold as shown. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0504.html&quot;&gt;AIM 5-4-6 (4)&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If proceeding to an IAF with a published course reversal (procedure turn or hold­in­lieu of PT pattern), except when cleared for a straight in approach by ATC, &lt;strong&gt;the pilot must execute the procedure turn/hold­in­lieu of PT, and complete the approach&lt;/strong&gt;. [emphasis mine]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The IFH that you cited in your question has similar wording:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For a hold-in-lieu-of PT, the holding pattern direction &lt;strong&gt;must be flown as depicted&lt;/strong&gt; [emphasis mine]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Occasionally&lt;/em&gt; ATC will act surprised or get frustrated with you for flying a reversal when you're within a 90° turn of the initial segment's course, but unless they specify straight in you're doing the right thing. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-06-02T14:22:54.847" LastActivityDate="2015-06-02T14:22:54.847" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15291" PostTypeId="1" AcceptedAnswerId="15293" CreationDate="2015-06-02T03:39:27.093" Score="8" ViewCount="1190" Body="&lt;p&gt;What are the rules and regulations specified by FAA about the code of conduct of flight crew members?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, are there any rules which specify behavior of passengers with crew members?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="572" LastEditDate="2015-06-02T06:15:44.117" LastActivityDate="2015-06-02T08:53:27.327" Title="Are there rules governing the conduct of flight attendants?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;aircraft-operations&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15292" PostTypeId="1" AcceptedAnswerId="15296" CreationDate="2015-06-02T05:31:14.073" Score="5" ViewCount="1601" Body="&lt;p&gt;I was intrigued to see this mentioned in passing,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://robbreport.com/aviation/cirrus-aircrafts-vision-sf50-personal-jet-completes-flight-testing-video&quot; rel=&quot;noreferrer&quot;&gt;http://robbreport.com/aviation/cirrus-aircrafts-vision-sf50-personal-jet-completes-flight-testing-video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it true that some new products now have this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they actually work, are there any demo videos, who pioneered it, in what situations is it actually useful, etc?&lt;/p&gt;&#xA;" OwnerUserId="3288" LastEditorUserId="755" LastEditDate="2015-10-21T03:14:05.143" LastActivityDate="2019-03-20T09:09:25.797" Title="Do some aircraft now have &quot;full aircraft&quot; parachutes?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;airframe-parachute&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15293" PostTypeId="2" ParentId="15291" CreationDate="2015-06-02T06:19:28.013" Score="8" Body="&lt;p&gt;The FAA is responsible for safety regulations and standards, not for code of conducts or courtesy regulations for interactions between flight attendants and passengers. Flight attendants are bound to certain behaviour only by their employer and their code of conduct, additionally to any national law that prohibits insulting others or harming them otherwise.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-06-02T06:19:28.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15295" PostTypeId="1" AcceptedAnswerId="15307" CreationDate="2015-06-02T06:34:06.800" Score="36" ViewCount="35561" Body="&lt;p&gt;There are many instances where pilots need to eject out of the cockpit due to emergency situations, and after such an ejection from some modern aircraft, pilots are deemed unfit to fly airplanes for some years. Why is this done? What is the minimum number of years after which a pilot is deemed fit to fly again?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="7670" LastEditDate="2015-06-05T17:41:56.093" LastActivityDate="2020-04-21T09:48:11.737" Title="Why are pilots deemed unfit to fly after emergency ejection?" Tags="&lt;emergency&gt;&lt;pilots&gt;&lt;ejection-seat&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15296" PostTypeId="2" ParentId="15292" CreationDate="2015-06-02T06:37:12.050" Score="14" Body="&lt;p&gt;Yes, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ballistic_parachute&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ballistic Recovery Systems&lt;/a&gt; or Ballistic Parachutes (BRS) are now being implemented in newer aircraft where the manufacturer can provide them or where they are required by law. In Germany, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ultralight_aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ultralights&lt;/a&gt; are required to have an installed BRS to be deemed airworthy.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In Europe the sporting (FAI) definition limits the maximum take-off weight to 450 kg (992 lb) (472.5 kg (1,042 lb) if a ballistic parachute is installed) and a maximum stalling speed of 65 km/h (40 mph).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The general idea is to allow the airframe to glide down to the surface and being attached to the airframe, the time saving for pilots to otherwise have to jump out and open their own parachutes (if equipped) is substantial. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first parachutes were used by Comco in 1982:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1982 Comco Ikarus developed the FRS rocket-launched parachute system for its ultralight and hanglider aircraft.&lt;a href=&quot;https://en.wikipedia.org/wiki/Ultralight_aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;2&lt;/a&gt; In 1998 Cirrus Aircraft provided the first ballistic parachutes as standard equipment on their line of type certified aircraft, the Cirrus SR20.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ByKg9.jpg&quot; alt=&quot;Cirrus BRS&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: WikiMedia Commons - Author: NASA)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a Video of the Cirrus Airframe Parachute System in action:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=gBCUQlF3MMU&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tuJqX.jpg&quot; alt=&quot;CAPS in Action&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://www.youtube.com/watch?v=gBCUQlF3MMU&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube&lt;/a&gt; - Author: AIRBOYD)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;An entry on &lt;a href=&quot;https://aviation-safety.net/wikibase/wiki.php?id=180979&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.aviation-safety.net&lt;/a&gt; about the Cirrus parachute system:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aircraft experienced a deployment of the Cirrus Airframe Parachute System (CAPS) over west Fayetteville, Arkansas. The airplane came to rest on a roadway shoulder sustaining substantial damage. There was 4 occupants on board, at least two people taken to the nearest hospital with minor injuries, according Police Department.&#xA;  The plane started having oil pressure issues immediately after take off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="14897" LastEditDate="2019-03-20T09:09:25.797" LastActivityDate="2019-03-20T09:09:25.797" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="15298" PostTypeId="1" AcceptedAnswerId="15308" CreationDate="2015-06-02T07:30:10.727" Score="8" ViewCount="1026" Body="&lt;p&gt;I was on a Wizz Air flight the other day and the safety instructions leaflet had a CM ruler running down the side of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rPqDq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1657" LastActivityDate="2015-06-02T10:05:33.977" Title="Why do these safety instructions have a ruler on them?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15299" PostTypeId="2" ParentId="15298" CreationDate="2015-06-02T07:40:16.723" Score="2" Body="&lt;p&gt;The rulers are there for measurement of anything you wish to measure in flight (which mostly includes measuring the sizes of the baggage of the consumer if there is a doubt about the size). Such rulers come in handy as big bags which are above the foretold measurements are quite common, so the flight attendants leave it up to the consumer to measure their own bags and not cause any hassle to the airlines.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-02T07:40:16.723" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15300" PostTypeId="1" AcceptedAnswerId="15301" CreationDate="2015-06-02T07:48:12.540" Score="11" ViewCount="1363" Body="&lt;p&gt;Let's take the case of the Airbus A320 family of aircraft. Airbus manufactures A318, A319, A320 and A321 planes, which all belong to the same family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the need to manufacture multiple aircraft from the same family having different ranges and capacity, when one could just invest in making just two or three different planes from three different families providing a wide range of range (distance) and capacity?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="7670" LastEditDate="2015-06-08T00:13:29.070" LastActivityDate="2015-06-08T00:13:29.070" Title="Why do aircraft manufacturers produce families of aircraft?" Tags="&lt;commercial-aviation&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15301" PostTypeId="2" ParentId="15300" CreationDate="2015-06-02T08:06:05.700" Score="25" Body="&lt;p&gt;There are several advantages, here are a few:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Design costs are lower for a family of aircraft; major parts of the aircraft are the same in the family.&lt;/li&gt;&#xA;&lt;li&gt;A family of aircraft share the same type certificate. This means it is cheaper for the manufacturer to certify a family of aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Within a family of aircraft, pilots can operate all aircraft with no&#xA;or very little additional training required. This saves the airline a&#xA;lot of money.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance on a family of aircraft is cheaper since the majority of&#xA;parts are common to all family members. This means having less spare&#xA;parts in stock and less training for maintenance personnel.&lt;/li&gt;&#xA;&lt;li&gt;For an airline there is often a benefit in having some capacity&#xA;diversity in a fleet. A new route often starts at low capacity. When&#xA;the volume of passengers rises replacing the flight by a  larger&#xA;aircraft from the same family is not disruptive to crew schedules.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-02T09:03:36.543" LastActivityDate="2015-06-02T09:03:36.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15302" PostTypeId="1" AcceptedAnswerId="15304" CreationDate="2015-06-02T08:40:02.543" Score="5" ViewCount="1130" Body="&lt;p&gt;I recently heard the term QBD which the &lt;a href=&quot;http://www.aviationdictionary.org/QBD&quot; rel=&quot;nofollow&quot;&gt;Aviation Dictionary&lt;/a&gt; explains is the fuel endurance in terms of hours. If it is an acronym, what is its expansion? If not, what is it derived from?&lt;/p&gt;&#xA;" OwnerUserId="8721" LastEditorUserId="572" LastEditDate="2015-06-02T09:04:29.107" LastActivityDate="2015-06-02T11:42:51.830" Title="What does QBD stand for?" Tags="&lt;fuel&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-06-02T11:36:06.030" ContentLicense="CC BY-SA 3.0" />
  <row Id="15303" PostTypeId="2" ParentId="15295" CreationDate="2015-06-02T08:45:11.420" Score="15" Body="&lt;p&gt;I don't know anything about minimum periods - but that may depend on the air force in question.  (Maybe someone else knows.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Medical complications can arise years after an ejection.  A fairly well known case I've heard about is the astronaut Michael Collins, who ejected from an aircraft in the 1950s.  More than ten years later he started to notice leg problems, these were traced to bone spurs in neck vertebrae, probably caused by the ejection.  Surgery fixed the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Collins goes into this and many other details in his biography by the way.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-06-02T08:45:11.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15304" PostTypeId="2" ParentId="15302" CreationDate="2015-06-02T08:45:27.300" Score="4" Body="&lt;p&gt;It comes from &lt;a href=&quot;https://en.wikipedia.org/wiki/Q_code&quot; rel=&quot;nofollow&quot;&gt;Q codes&lt;/a&gt; for morse communication. They where set up without a clear rhyme or reason that I can see besides being ordered alphabetically.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-06-02T11:42:51.830" LastActivityDate="2015-06-02T11:42:51.830" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15305" PostTypeId="2" ParentId="15291" CreationDate="2015-06-02T08:53:27.327" Score="4" Body="&lt;p&gt;Flight crew members are bound by the rules as specified by the airlines. Additionally, pilots are bound by the rules decided by the Air Lines Pilots' Association, International. These are called code of ethics, and you can have a look at them &lt;a href=&quot;http://www.alpa.org/en/about-alpa/what-we-do/code-of-ethics&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-02T08:53:27.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15306" PostTypeId="2" ParentId="15275" CreationDate="2015-06-02T08:57:02.643" Score="1" Body="&lt;p&gt;After consulting with some seniors, I've come to know that Ansys workbench (Which effectively uses NASTRAN on the backend) has the proper tools for achieving this using combination of FEM and CFD&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-02T08:57:02.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15307" PostTypeId="2" ParentId="15295" CreationDate="2015-06-02T09:02:17.863" Score="45" Body="&lt;p&gt;Ejection Seats are not a free ticket out. They are incredibly violent and rough on your body. This newspaper article has a more chilling quote from an interview: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;About &lt;strong&gt;one in three will get a spinal facture&lt;/strong&gt;, due to the force when the seat is ejected - the gravitational force is 14 to 16 times normal gravity and it might be applied at 200G per second. Bruising and abrasions are typical from the shock of the chute opening or the air blast. In the early days, there were cases where pilots would eject into very-high-speed air and it would whip their arms behind and break them, pop their shoulders out; same thing could happen to the legs. &lt;a href=&quot;http://www.smh.com.au/national/education/how-dangerous-is-it-to-eject-from-a-fighter-jet-20120730-239mp.html&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Hence, it is very possible to get back pains and a host of other problems as a result of ejecting. Since these type of things are not that easily reversible, you'd rather take the safe path and remove then from the cockpit than put then back in a work environment that known is pretty hard on your body. Aircrew seem to agree:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“It was the most violent thing I’ve ever felt in my life,” says one of the B-1 crew members, whom the Air Force asked me to identify as “Captain IROC.” “I lost a full inch in height,” because his spine absorbed such tremendous G-forces. &lt;a href=&quot;http://www.airspacemag.com/military-aviation/how-things-work-ejection-seats-29088450/#eVsKyTAhpzQS7pBE.99&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Modern ejection seats are however increasingly intelligent and will gauge the ejection force applied to the conditions, cutting down the number of serious cases. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://emj.bmj.com/content/17/5/371.full&quot;&gt;paper&lt;/a&gt; discusses the symptoms of four individuals who crashed their jets in mid-air. The medical problems encountered with ejection can be classified as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Injuries from the emergency that causes ejection—fire or collision.&lt;/li&gt;&#xA;  &lt;li&gt;Canopy jettison: burns from “MDC splatter” and cuts from fragmented plastic. For these reasons, aircrew are always advised to wear their visors down, to protect the face.&lt;/li&gt;&#xA;  &lt;li&gt;Firing of ejection gun: spinal injuries.&lt;/li&gt;&#xA;  &lt;li&gt;Entering airflow: wind blast may cause lung damage; seat tumbles at variable speed, which may be as high as 180 rpm. (All seats have a drogue parachute or deployable aerodynamic panels to prevent tumbling); flail injuries to extremities.&lt;/li&gt;&#xA;  &lt;li&gt;Parachute deployment: snatch injuries.&lt;/li&gt;&#xA;  &lt;li&gt;Landing: lower limb injuries.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-02T09:15:15.360" LastActivityDate="2015-06-02T09:15:15.360" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15308" PostTypeId="2" ParentId="15298" CreationDate="2015-06-02T10:05:33.977" Score="6" Body="&lt;p&gt;This looks like just a courtesy tool on the safety card, but doesn't actually have a requirement or purpose. Previous versions of their safety card did not have this courtesy tool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pcoKt.jpg&quot; alt=&quot;Wizzair Safety Card&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: aviationfreaks.freeforums.org)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-06-02T10:05:33.977" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15309" PostTypeId="1" CreationDate="2015-06-02T10:35:41.373" Score="5" ViewCount="1843" Body="&lt;p&gt;I asked a related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9014/how-hard-is-it-to-fly-with-night-vision-goggles/15133#15133&quot;&gt;How hard is it to fly with night vision goggles?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears from the answers so far that there are differing opinions, and I guess it might depend on the quality/age/capability of the equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone was flying non-commercially (Part 91), Private Pilot (or higher) and it was VFR flight, if the pilot owned a pair of &lt;a href=&quot;http://https://www.ownthenight.com/helmets/product/447-anvis-9-night-vision-aviator-s-goggles/category_pathway-36.html#specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;The ANVIS 9, Aviator Night Vision Goggles, Model M949&lt;/a&gt;, for example, could they legally fly around with them in their own airplane at night (and be acting as Pilot-In-Command)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Assume that they are a safe, prudent aviator, and took efforts to properly train themselves on the equipment and flew with a safety pilot until they were comfortable in the air with the equipment).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be any different if they were flying IFR (appropriately-rated and on an instrument flight plan)?&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-06-05T21:38:12.713" Title="Is a civilian pilot allowed to fly under part 91 rules with Night Vision Goggles?" Tags="&lt;faa-regulations&gt;&lt;equipment&gt;&lt;night-flying&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15310" PostTypeId="2" ParentId="15309" CreationDate="2015-06-02T10:51:52.473" Score="5" Body="&lt;p&gt;Theoretically? Yes. In practice? Maybe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FARs provide for civilian operations under NVGs, but the story is a bit more complicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NVG operations requirements for pilots are covered in 61.31(k) for obtaining an endorsement and 61.57(f) for currency. Reading over the wording, the FAA appears to take the same general approach that they do with tailwheels: i.e. get trained and endorsed and then stay current.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is with the aircraft rather, as 91.205(h) requires, in addition to day and night VFR equipment, a gyroscopic pitch and bank indicator (not typically an issue), a generator or alternator as per IFR reqs (again, not generally an issue), interior and exterior lighting appropriate for NVG ops (may be an issue), and a radar altimeter (definitely an issue in almost all light, and some not-so-light, aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure about the goggles themselves, maybe there's a TSO out there giving tech specifications for aviation-specific NVGs?&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-06-02T10:51:52.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15311" PostTypeId="1" AcceptedAnswerId="15320" CreationDate="2015-06-02T10:54:44.697" Score="27" ViewCount="18259" Body="&lt;p&gt;This subject has been partially covered before here &lt;a href=&quot;https://aviation.stackexchange.com/questions/12261/is-it-possible-to-do-a-barrel-roll-in-a-large-aircraft-like-a-b737&quot;&gt;Is it possible to do a barrel roll in a large aircraft like a B737?&lt;/a&gt; and here &lt;a href=&quot;https://aviation.stackexchange.com/questions/489/is-it-safe-to-roll-an-airplane-that-isnt-approved-for-it?lq=1&quot;&gt;Is it safe to roll an airplane that isn&amp;#39;t approved for it?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a airliner such as say a 777-300 had enough height, could it theoretically do a loop or similar aerobatics? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am supposing that there is no passengers, luggage, hostesses and minimum fuel on board etc - so minimum weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, taking into account the loop - if it couldn't achieve the loop by pulling up - could it achieve it by going nose down instead? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;IE: The aircraft goes nose down till it is upside down then pulls up - a mirror version of a normal loop basically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other questions go over the reasons why not to roll a large aircraft, I want to know if other aerobatics (specifically loops) are theoretically possible.&lt;/p&gt;&#xA;" OwnerUserId="8300" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2018-01-14T02:31:45.003" Title="Can large airliners do aerobatics such as loops?" Tags="&lt;airliner&gt;&lt;aerobatics&gt;" AnswerCount="6" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15312" PostTypeId="1" AcceptedAnswerId="15325" CreationDate="2015-06-02T11:16:54.800" Score="10" ViewCount="7497" Body="&lt;p&gt;I have studied that the main three systems for performing Precision Approaches (PA) are the &lt;strong&gt;ILS&lt;/strong&gt; (Instrumental Landing System), &lt;strong&gt;PAR&lt;/strong&gt; (Precision Approach Radar) and &lt;strong&gt;MLS&lt;/strong&gt; (Microwave Landing System).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in most of the airports the ILS is implemented as the main PA aid; while the others are often developed, but not fully implemented or unused. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Questions:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;What's the reason that the ILS is the most popular PA system? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the benefits and disadvantages of the other systems for not being as much considered? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do they compare regarding approach performances?&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="22726" LastEditDate="2019-08-19T01:08:36.463" LastActivityDate="2019-08-19T01:08:36.463" Title="Precision Approach systems: Why is ILS used more frequently than PAR and MLS?" Tags="&lt;approach&gt;&lt;ils&gt;&lt;microwave-landing-system&gt;&lt;par&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15313" PostTypeId="1" AcceptedAnswerId="15314" CreationDate="2015-06-02T11:36:24.867" Score="15" ViewCount="10803" Body="&lt;p&gt;I've been asking myself for a while how ATC can maintain air traffic safety with regard to military aircraft - or if they just don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, all bigger planes (let's for now focus on commercial airliners) have mandatory transponders and warning systems like TCAS and similar. By usage of such systems, ATC knows their position, altitude, heading etc. which is used for planning of take-offs and landings just as well as air traffic safety. Also, systems like TCAS allow pilots to directly respond to unsafe situations even if ATC &quot;didn't see it coming&quot;. In short, lots of regulations and techniques to make flying safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I know even less about military aircraft, but I do know they have transponders, too. I suppose, since enemies would have it a bit easy, those transponders don't operate the same way civil transponders do; or at least they use different frequencies, encryption and what-not. I don't know if they have TCAS but, I suppose, even that could possibly be exploited by enemies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I assume correctly, civil ATC cannot necessarily see military aircraft. I've read &lt;a href=&quot;https://aviation.stackexchange.com/questions/12401/how-much-jurisdiction-does-the-faa-have-over-military-aircraft&quot;&gt;in another question&lt;/a&gt; that FAA doesn't have much power over military but that's just the US anyways. Also, the answer in &lt;a href=&quot;https://aviation.stackexchange.com/questions/13856/are-there-laws-about-how-close-military-aircraft-can-fly-to-passenger-jets-and&quot;&gt;yet another question&lt;/a&gt; suggests that military aircraft do not have to maintain separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what's the verdict? Do military aircraft assume civil regulations while not in &quot;combat mode&quot;? Or are civil ATC indeed oblivious of military air movements and the military has to provide safety by regulating military and watching civil traffic?&lt;/p&gt;&#xA;" OwnerUserId="8509" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2018-02-11T10:55:57.510" Title="How can civil ATC maintain safety with military aircraft around?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;military&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15314" PostTypeId="2" ParentId="15313" CreationDate="2015-06-02T11:56:40.997" Score="18" Body="&lt;p&gt;Military aircraft do have transponders that can reply to civil ATC radar and TCAS interrogations. Normally military aircraft operating in civil airspace are visible to civilian ATC and also will trigger &lt;a href=&quot;http://avherald.com/h?article=44e8a206/0000&quot;&gt;TCAS advisories&lt;/a&gt; and alerts if they are getting close to airliners. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During  wartime operations, and sometimes during combat practice in dedicated airspace, the transponder is operated in a different mode and will not be replying to civil radar interrogations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically when operating in civil airspace, military aircraft will fly under the civil regulations for that airspace. Training flights are usually conducted in dedicated airspace under military traffic control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases the military ATC assumes responsibility over military aircraft in otherwise civil ATC controlled airspace. In such a case the military ATC will be responsible for the separation between the military aircraft themselves and between military and civilian aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other cases military aircraft may be allowed to maintain their separation from each other on their own, without civil ATC interfering in their operations. This allows for operations where military aircraft flying close to each other like formation flying and aerial refuelling outside the dedicated military airspace. In the USA these operations are called MARSA (Military Assumes Responsibility for Separation of Aircraft). Civil ATC is responsible for keeping Instrument Flight Rules (IFR) aircraft separated from MARSA operations. Visual Flight Rules (VFR) pilots have to maintain separation visually from MARSA flights and vice-versa. If VFR pilots are in contact with ATC they will be advised of ongoing military operations.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-02T12:25:28.977" LastActivityDate="2015-06-02T12:25:28.977" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15316" PostTypeId="1" AcceptedAnswerId="15334" CreationDate="2015-06-02T12:13:36.973" Score="11" ViewCount="7021" Body="&lt;p&gt;For a normal civil aviation aircraft, what are the pros and cons of having Canard control surfaces or horizontal tail control surface?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-11-11T14:57:31.667" LastActivityDate="2016-11-11T14:57:31.667" Title="What are the pros and cons of having canard control surfaces versus a horizontal tail control surface?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;stability&gt;&lt;control-surfaces&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15318" PostTypeId="2" ParentId="15313" CreationDate="2015-06-02T12:46:37.453" Score="0" Body="&lt;p&gt;Sometimes they just can't. Basically you can turn off transponder on any airplane. In this case all ATC can rely on is the primary radar if it's good enough and they can see objects like military aircraft. The good example will be Russians flying bombers around Europe. There have been several near collisions already. Best options is to send military jet to intercept bomber and follow it. If intercepting jet has transponder on then ATC can know approximate position of the bomber.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-06-02T12:46:37.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15319" PostTypeId="2" ParentId="15311" CreationDate="2015-06-02T12:54:54.797" Score="8" Body="&lt;p&gt;Airplanes can sustain more positive G forces than negative G forces because of their construction. Your described opposite loop is only for very advanced aerobatic airplanes and pilots because negative G forces are involved. I think normal loops are possible if performed by a skilled pilot like a test pilot, but are too risky or too expensive (in case of failure) to try.  A Boeing 777 costs $300 million.  Who will want to over-stress an airframe that costs millions just for a loop?!&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="6919" LastEditDate="2015-06-03T11:33:39.467" LastActivityDate="2015-06-03T11:33:39.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15320" PostTypeId="2" ParentId="15311" CreationDate="2015-06-02T13:04:06.363" Score="24" Body="&lt;h2&gt;Design&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The key point is that these vehicles are not designed to perform such maneuvers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A coast-guard lifeboat is designed to self-recover from a capsize and can &lt;a href=&quot;https://www.youtube.com/watch?v=VmWhp8Qw9Fg&quot; rel=&quot;noreferrer&quot;&gt;roll through 360 degrees without significant structural damage&lt;/a&gt;. A cruise-liner would not survive being rolled over completely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a vehicle is not designed to perform a high stress maneuver it is safe to assume an unmodified vehicle cannot do so without incurring severe damage.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Inside loop&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Regarding an inside loop, the &lt;a href=&quot;http://www.straightdope.com/columns/read/229/is-it-possible-to-loop-or-roll-a-747-jet&quot; rel=&quot;noreferrer&quot;&gt;world's smartest man&lt;/a&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Looping a 747 or a DC-10 would be trickier [than rolling one ...]  Boeing suspects its planes could make it, but since no one has ever been silly enough to try, there's no way of knowing for sure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Outside loop&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An outside loop is much much more stressful on airframe and pilots as it involves negative G. Airliners have flight envelopes that have much less capability under negative G. There must be a very high probability the aircraft would break up when attempting an outside loop.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Roll&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A barrel roll is a less stressful maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;60 years ago, in 1955, &lt;a href=&quot;http://en.wikipedia.org/wiki/Alvin_M._Johnston&quot; rel=&quot;noreferrer&quot;&gt;&quot;Tex&quot; Johnston&lt;/a&gt;, a Boeing test pilot performed a &lt;a href=&quot;https://www.youtube.com/watch?v=Ra_khhzuFlE&quot; rel=&quot;noreferrer&quot;&gt;barrel roll in a Boeing 707&lt;/a&gt;. So far as I can find out, no one has since deliberately attempted to replicate this stunt in a commercial airliner. At the time of publishing his autobiography, the pilot claimed in a &lt;a href=&quot;http://community.seattletimes.nwsource.com/archive/?date=19900228&amp;amp;slug=1058594&quot; rel=&quot;noreferrer&quot;&gt;newspaper report&lt;/a&gt; that the stunt was planned by him but unknown to his boss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;in 1985 &lt;a href=&quot;http://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot; rel=&quot;noreferrer&quot;&gt;China Airlines 006&lt;/a&gt;, a 747, inadvertently executed a half roll but suffered structural damage. It rolled to 60 degrees before the pilot disengaged the autopilot, the pilots suffered spatial disorientation and the roll continued into a dive. The pilots obviously weren't flying the aircraft within its limits - meaning you can't read a lot into this, other than it might be easy to break up the aircraft while attempting this sort of maneuver.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-03T14:52:04.060" LastActivityDate="2015-06-03T14:52:04.060" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="15321" PostTypeId="2" ParentId="15311" CreationDate="2015-06-02T13:13:44.343" Score="15" Body="&lt;p&gt;Probably not, due to structural strength issues. A barrel roll is one thing; they can be performed at a positive load factor through the whole maneuver (assuming sufficient control authority). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Loops on the other hand will need much greater loadings in the &quot;fast&quot; portions in order to keep the loop &quot;round&quot; and to allow the maneuver to be completed without stalling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inverted loops are even more extreme as the aircraft is accelerating into the maneuver, requiring potentially greater loads on the airframe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside loops... might as well forget it, the negative G-Loads are more or less guaranteed to cause an airliner airframe to fail; negative Limit Load Factor for Part 25 cert requirements is -1 G and Ultimate Load Factor is -1.5.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who knows, maybe Boeing over-engineered enough to allow a 74- to take the 4+ Gs it would need to in order to complete a loop, but I'm skeptical they could build that much strength into the structure, for weight reasons if nothing else. &lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="1961" LastEditDate="2018-01-12T17:22:29.143" LastActivityDate="2018-01-12T17:22:29.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15323" PostTypeId="2" ParentId="15311" CreationDate="2015-06-02T14:55:58.670" Score="1" Body="&lt;p&gt;Check out &lt;a href=&quot;https://www.youtube.com/watch?v=AaA7kPfC5Hk&quot; rel=&quot;nofollow&quot;&gt;Tex Johnston's 707 prototype barrel roll&lt;/a&gt;.  While it isn't large by today's standards, it did involve a plane that became an airliner.&lt;/p&gt;&#xA;" OwnerUserId="8725" LastEditorUserId="1696" LastEditDate="2015-06-04T15:52:24.567" LastActivityDate="2015-06-04T15:52:24.567" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15324" PostTypeId="2" ParentId="12462" CreationDate="2015-06-02T15:01:57.627" Score="1" Body="&lt;p&gt;Use of RNAV began in late 1960’s . Some airlines began exploring RNAV systems  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;KLM/SwissAir/SAS/UTA had a cooperative effort&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Swissair became responsible for the development of a database to&#xA;support this effort&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In June 1973, National Air DC-10 equipped with Collins ANS-70 conducted RNAV operation, including approaches in VMC, with database. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In January 1983, the Federal Aviation Administration revoked all RNAV routes in the contiguous United States due to findings that aircraft were using inertial navigation systems rather than the ground-based beacons, and so cost-benefit analysis was not in favor of maintaining the RNAV routes system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RNAV was reintroduced after the large-scale introduction of satellite navigation.And, since 1990 it is there in almost all the planes you see.&#xA;So, as a rough estimate it would be &lt;strong&gt;more than 90%&lt;/strong&gt;. Because, most of the pre-1990 planes have either been upgraded or grounded.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources: &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_navigation&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, &lt;a href=&quot;https://www.federalregister.gov/articles/2003/05/09/03-11638/establishment-of-area-navigation-routes-rnav#h-4&quot; rel=&quot;nofollow&quot;&gt;Federal Register&lt;/a&gt;, &lt;a href=&quot;http://www.flighttraining.be/da42/rnav_basics_ifr_g1000_handouts_v2_1.pdf&quot; rel=&quot;nofollow&quot;&gt;This Article&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-06-02T15:01:57.627" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15325" PostTypeId="2" ParentId="15312" CreationDate="2015-06-02T15:03:28.357" Score="13" Body="&lt;p&gt;At least in the U.S., ILS is popular because it is popular. It's relatively cheap to install and operate, the receivers share technology with VOR, and it is already installed everywhere. Momentum (and cost of replacement) has a lot to do with the failure and success of navigation systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;MLS requires new hardware on the ground and in aircraft. The FAA tried to roll it out in the U.S. in the 80s, with a goal of replacing ILS by 2010, and utterly failed. The equipment was expensive for aircraft and ground facilities, and the cost of developing the approach procedures was high, as well as each approach needs tailored antenna programming (ILS is reasonably standardized). The adoption rate was low and the benefits (better arrival area guidance, better accuracy in some cases) were duplicated by the much cheaper GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Precision GPS (LPV or LNAV/VNAV approaches) only appeared with the development of the Space Based Augmentation System (SBAS), also known as the Wide Area Augmentation System (WAAS). Augmented GPS has higher vertical precision and allows a single navigation system to be used for enroute, terminal, and precision approach guidance, a huge cost savings. The relatively new &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/laas/&quot; rel=&quot;noreferrer&quot;&gt;Ground Based Augmentation System&lt;/a&gt; (GBAS, originally called LAAS) adds high precision approach capability bringing GPS approaches closer to ILS and MLS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PAR exists, but you may misunderstand what it is: it is a controller staring at a radar scope and issuing pilots instructions. It's stressful for pilots and controllers and very time consuming. Outside of military facilities you would be hard pressed to find a place to practice a PAR these days, at least in my experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order of precision, high to low:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;MLS&lt;/li&gt;&#xA;&lt;li&gt;GPS with GBAS (uncommon)&lt;/li&gt;&#xA;&lt;li&gt;ILS &lt;/li&gt;&#xA;&lt;li&gt;GPS with WAAS (common, aka LPV)&lt;/li&gt;&#xA;&lt;li&gt;PAR&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In order of (estimated) total cost, high to low:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;MLS (very expensive install + unique approach design + maintenance)&lt;/li&gt;&#xA;&lt;li&gt;PAR (relatively cheap install + costly workforce; educated guess on my part, could be cheaper than ILS?)&lt;/li&gt;&#xA;&lt;li&gt;ILS (expensive? install + simple approach design + maintenance)&lt;/li&gt;&#xA;&lt;li&gt;GPS with * (no install, simple approach design, no obvious maintenance)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-06-03T16:05:53.543" LastActivityDate="2015-06-03T16:05:53.543" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15326" PostTypeId="1" AcceptedAnswerId="15395" CreationDate="2015-06-02T15:06:22.523" Score="3" ViewCount="19079" Body="&lt;p&gt;While reading the &lt;a href=&quot;https://www.faa.gov/about/office_org/field_offices/fsdo/stl/local_more/presentations/media/Part_135_Airworthiness_Requirements.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA presentation on Part 135 Airworthiness Requirements&lt;/a&gt;, on slide 7 where it discusses maintenance, the list includes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;inspection, overhaul, repair, preservation, and the replacement of parts, but excluding preventive maintenance&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am sure that the other regulatory bodies have their own, similar lists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that an aircraft overhaul is one of the major processes involved in (especially commercial) aircraft maintenance. What exactly is meant by overhaul? What is done to an aircraft when it is overhauled? And finally, why is it so important for an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="790" LastEditDate="2015-06-03T19:07:42.533" LastActivityDate="2015-06-04T03:43:55.323" Title="What is an Aircraft Overhaul?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15328" PostTypeId="1" AcceptedAnswerId="15331" CreationDate="2015-06-02T15:11:40.003" Score="12" ViewCount="7350" Body="&lt;p&gt;Usually, cabin pressure of an airliner is kept at a value corresponding to an altitude of not more than about 2000m. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I heard that before takeoff, the pressure is already increased a little for higher stability of the fuselage. Maybe, this is wrong, but I had another experience:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was in a 737-800 flying at 11500m. While the aircraft sank on approach for landing, I felt that typical pressure on my ears several times though we still were above 7000m. So, the cabin pressure already changed at that high altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, how is cabin pressure related to outside pressure during the entire flight? &lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="13197" LastEditDate="2019-01-20T12:12:00.597" LastActivityDate="2020-12-26T04:17:47.523" Title="What's the relation between cabin pressure and altitude?" Tags="&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="15330" PostTypeId="2" ParentId="15328" CreationDate="2015-06-02T15:25:14.140" Score="4" Body="&lt;p&gt;To the best of my knowledge, cabins are never pressurized before takeoff. This is a safety issue as it would inhibit door opening. The pressure would make them impossible to open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on aircraft, the aircraft might be kept at either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At a constant pressure difference, i.e. the cabin altitude increases evenly up to cruise altitude. This would indeed mean that the moment it takes off it starts to build up a pressure in relation to takeoff. This means that the pressure difference is perceived as gradual.&lt;/li&gt;&#xA;&lt;li&gt;At a fixed minimum pressure, i.e. the valve just closes at (for instance) 2000m and then maintains 2000m altitude all the way up, just building an increasing pressure differential.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both methods have to take into account the landing altitude, since you  don't want to land the aircraft pressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The former is more common since it's nicer. This would also explain why you perceived a change even at high altitude. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-02T15:44:51.407" LastActivityDate="2015-06-02T15:44:51.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15331" PostTypeId="2" ParentId="15328" CreationDate="2015-06-02T15:44:46.770" Score="19" Body="&lt;p&gt;Here is a plot of cabin pressure on one flight. You can see a small increase in pressure right before takeoff. The decrease and increase in pressure is fairly constant during climb and descent. The pressure will change based on the aircraft's altitude, and will not reach a minimum limit until closer to the aircraft's service ceiling. This keeps pressure changes as slow as possible while giving a lower cabin altitude when below the service ceiling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/B94bv.jpg&quot; alt=&quot;Cabin pressure over time&quot;&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.meteormetrics.com/flightpressure.htm&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-06-02T15:44:46.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15332" PostTypeId="2" ParentId="15328" CreationDate="2015-06-02T15:54:52.817" Score="12" Body="&lt;p&gt;On a number of aircraft types the cabin pressure is increased during the take-off roll, ensuring there is a slight over pressure when the aircraft rotates. This prevents some sudden changes in cabin pressure during rotation when the cabin exhaust valve is exposed to changing airflows. The chart in @fooot's post clearly shows the initial increase in pressure during take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the climb the cabin pressure is slowly decreased. While a typical passenger jet may climb at speeds in excess of 2000 feet per minute, the cabin pressure will decrease at an equivalent rate of climb rarely exceeding 500 feet per minute. When the cabin pressure has dropped to an equivalent of about 7000 ft altitude (the aircraft will be much higher by that time) the cabin pressure is kept constant. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft starts to descent on approach to the airport, the cabin pressure is slowly increased at about a rate of 300 feet per minute. By the time the aircraft has reached the airport level, the cabin pressure should have reached ambient pressure. To achieve this, pilots have to set the cabin altitude for landing, otherwise the pressure will not equalize. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-02T16:01:04.620" LastActivityDate="2015-06-02T16:01:04.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15333" PostTypeId="2" ParentId="15235" CreationDate="2015-06-02T18:55:19.610" Score="0" Body="&lt;p&gt;A hybrid just does not make sense on a plane for the same reason that a turboprops make sense on a plane and turboshafts do not for a car. Cars have rapidly varying load, planes do not. Also planes do not brake in the air (often), so regenerative brakes would be worthless. Overall the electric motor in a hybrid car is in effect used to smooth out the load on the internal combustion engine, and allow it to run at its most efficient rpm. In a turboprop, the variable pitch does the same thing, but much better.&lt;/p&gt;&#xA;" OwnerUserId="600" LastActivityDate="2015-06-02T18:55:19.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15334" PostTypeId="2" ParentId="15316" CreationDate="2015-06-02T19:11:24.913" Score="12" Body="&lt;p&gt;For statically stable aircraft, the canard is a spoiler in disguise. It will create a strong downwash right behind itself, coupled with an upwash outward of $\pi$/4 of its semispan. With changing angle of attack and lift coefficient, the vertical position and the strength of both up- and downwash will change, so the wing incidence variation over wingspan can be made right for just one angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Pros&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The force to effect flight path changes works the right way, so pitch response times of canards are slightly better than those of a conventional configuration.&lt;/li&gt;&#xA;&lt;li&gt;The wing can be further aft, so in short business jets the cabin might not interfere with the wing spar.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Cons&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The induced drag at off-design points is higher than that of a comparable conventional configuration.&lt;/li&gt;&#xA;&lt;li&gt;The bigger lifting surface must keep some stall margin, so the total lift coefficient will be smaller than that of a comparable conventional configuration. In the end, a canard will need more wing area.&lt;/li&gt;&#xA;&lt;li&gt;Control surface deflections will add to the already high lift coefficient of the canard plane, increasing lift demands on the surface with the smallest margins.&lt;/li&gt;&#xA;&lt;li&gt;The highest lift coefficient is needed at the surface with the smaller &lt;a href=&quot;http://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number&lt;/a&gt;. Normally, the reverse would be better.&lt;/li&gt;&#xA;&lt;li&gt;If the engines are mounted below and ahead of the wing, they will be hit by the wake of the canard, reducing intake efficiency and &lt;a href=&quot;http://en.wikipedia.org/wiki/Compressor_stall&quot; rel=&quot;noreferrer&quot;&gt;compressor stall&lt;/a&gt; margins.&lt;/li&gt;&#xA;&lt;li&gt;To make sure that the control surface will be the last thing on the plane to run into compressibility problems, it should have less lift coefficient and more sweep than the wing. In the end, a statically stable canard will have a lower cruise Mach number than a comparable conventional configuration.&lt;/li&gt;&#xA;&lt;li&gt;The landing gear must be made to retract into the fuselage, because the wing is too far behind the center of gravity to allow the gear to retract into the wing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I could go on, but I guess you see by now where this is heading …&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-03T09:41:19.743" LastActivityDate="2015-06-03T09:41:19.743" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15335" PostTypeId="1" AcceptedAnswerId="15336" CreationDate="2015-06-02T20:21:27.563" Score="23" ViewCount="2280" Body="&lt;p&gt;I was reading about flight &lt;a href=&quot;http://en.wikipedia.org/wiki/Red_Wings_Airlines_Flight_9268&quot; rel=&quot;noreferrer&quot;&gt;RWAF9268&lt;/a&gt; earlier today when a questions popped into mind.  When a large commercial jet touches down, is it required to try and come to a complete stop?  Or is it allowed to take off again if part of the craft fails (like the braking system, for example)?  And what factors would make a pilot decide to stay one the ground, or just abort the landing?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="100" LastEditDate="2020-05-06T13:01:38.240" LastActivityDate="2020-05-06T13:01:38.240" Title="When a large commercial jet touches down, is it committed to stopping?" Tags="&lt;landing&gt;&lt;accidents&gt;&lt;aircraft-failure&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15336" PostTypeId="2" ParentId="15335" CreationDate="2015-06-02T20:40:18.443" Score="17" Body="&lt;p&gt;&lt;strong&gt;Boldface&lt;/strong&gt; emergency procedures are procedures that the aircrew should have committed to memory and are written in bold text.  Generally speaking, the &lt;strong&gt;boldface&lt;/strong&gt; for all emergencies involving brake failures, gear failures, control failures, literally anything that involves control of the aircraft after touchdown, starts with:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If fly-away airspeed available:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1. Go-around&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If fly-away airspeed unavailable:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. Do specific airframe related items.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emergency procedures like these will be committed to memory, and then the only problem for the aircrew to solve will be if they have enough runway remaining to get airborne again.  If they don't have enough runway remaining then usually the fix to is apply emergency brakes (if the pedals hit the floor) or use backup nose wheel steering (for a steering failure) and ride it out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: use of these emergency procedures doesn't necessarily indicate a failure of an aircraft system.  If a sudden gust of wind at touchdown weathervanes the aircraft 45 degree off centerline, you can be sure the crew is checking for fly-away airspeed.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-06-02T20:40:18.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15337" PostTypeId="1" AcceptedAnswerId="15338" CreationDate="2015-06-02T20:40:53.733" Score="16" ViewCount="4289" Body="&lt;p&gt;In the modern day we have advanced planes, and advanced missile systems, however, how can you stop your missile firing at a friendly aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In planes like the F22 Raptor you can turn on sight lock, which is when you look at a plane through your helmet, the computer registers that there is a plane there, and it locks onto the plane with a missile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, let's say a friendly aircraft were to fly in front of you when you had sight lock turned on; would the missile fire at the friendly aircraft, or is there a piece of technology in the friendly aircraft which registers that it's with you? If so, could that potentially be used against you in modern day aerial warfare?&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1696" LastEditDate="2018-04-20T14:36:06.790" LastActivityDate="2019-02-10T08:05:32.427" Title="How can you stop your missile locking onto a friendly target?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;missiles&gt;&lt;f-22&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15338" PostTypeId="2" ParentId="15337" CreationDate="2015-06-02T20:52:59.107" Score="23" Body="&lt;p&gt;First off, very rarely will you shoot at an unidentified aircraft.  Most engagements require a visual ID, or a hostile action, prior to engagement. However, you will also program your aircraft with specific ROE logic that will indicate that certain aircraft are friendly, as identified by IFF transponders, Link 16, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can still lock up friendly aircraft, and we frequently do to facilitate rendezvous with friendly aircraft and to clear ourselves from traffic, but if your master switch goes to ARM and you have a friendly locked up, there's a good chance you won't be flying again for awhile, if ever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we lock up an aircraft, 99% of the time, it does not indicate an intention to shoot.  By using our radar and &quot;locking up&quot; a target we get target aircraft altitude, speed, range, target aspect, heading, $Vc$, etc, all useful things that come in handy for routine events.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-06-04T02:14:33.297" LastActivityDate="2015-06-04T02:14:33.297" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15339" PostTypeId="2" ParentId="15335" CreationDate="2015-06-02T20:53:21.443" Score="14" Body="&lt;p&gt;&lt;strong&gt;No, when an airliner touches down, it is &lt;em&gt;not&lt;/em&gt; committed to stop.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a &lt;em&gt;go around after touchdown&lt;/em&gt; is not an easy task and sometimes can be very dangerous. A hypothetical situation is &lt;strike&gt;&lt;a href=&quot;http://www.propilotmag.com/archives/2008/Dec08/A4_Pilot_techniques_p1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;discussed here&lt;/a&gt;&lt;/strike&gt; which is similar to &lt;a href=&quot;http://en.wikipedia.org/wiki/Red_Wings_Airlines_Flight_9268&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight 9268&lt;/a&gt; which you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to a landing, more runway is required for a takeoff. After the touchdown, pilots have very little time to decide to take off again if they cannot stop. Fortunately&lt;sup&gt;1&lt;/sup&gt;, most of the time, this decision is made very quickly. However, if an airplane is slowed down below the minimum safe go-around speed, there will (or may&lt;sup&gt;2&lt;/sup&gt;) not be enough runway remaining to take off again. Therefore, pilots should accept a runway overrun, as it is probably a lesser evil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To take off after a touchdown, there are several very important factors to consider. They include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Remaining runway&lt;br&gt;&#xA;&lt;em&gt;Probably the most important factor.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;If airplane is at or above minimum safe go-around speed, or can achieve with enough runway remaining&lt;/li&gt;&#xA;&lt;li&gt;Actual touchdown point&lt;/li&gt;&#xA;&lt;li&gt;Density altitude&lt;/li&gt;&#xA;&lt;li&gt;Wind&lt;/li&gt;&#xA;&lt;li&gt;Pilot reaction time (decision time)&lt;/li&gt;&#xA;&lt;li&gt;Inertia of the airplane&lt;/li&gt;&#xA;&lt;li&gt;Time required to configuration change&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: In cases when the pilots decide to abort the landing, they decide it within the first few seconds of touchdown. I found a &lt;a href=&quot;https://youtu.be/F1deY7EkNSA&quot; rel=&quot;nofollow noreferrer&quot;&gt;video of this&lt;/a&gt; (and &lt;a href=&quot;https://youtu.be/bMUdXJPUwm8&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;) showing the airplane took off very quickly when aborting the landing (after the wheels touched down). Most of the time, they abort the landing before touchdown, when the gears are just a few feet off the ground (as seen &lt;a href=&quot;https://youtu.be/7P9OAng32F0&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://youtu.be/mMvLuUJFHYk&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;: This depends on runway length.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2019-06-24T11:11:45.713" LastActivityDate="2019-06-24T11:11:45.713" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="15341" PostTypeId="1" AcceptedAnswerId="15366" CreationDate="2015-06-02T21:14:57.633" Score="6" ViewCount="2563" Body="&lt;p&gt;Stealth technology uses angles in the aircraft shape, and homogeneous orientation of the surfaces. In the &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22A Raptor&lt;/a&gt; wing leading edges, tail surfaces, air intake bypass doors, refueling aperture, etc have the same orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AF9yw.png&quot; alt=&quot;This is a example of planform alignment&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incoming radar waves are deflected in a different direction, giving the enemy the impression that there is nothing there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RsYKW.png&quot; alt=&quot;This is a example of planform alignment&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as mentionned in &lt;a href=&quot;http://en.wikipedia.org/wiki/Stealth_technology#Vehicle_shape&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;: &quot;&lt;em&gt;Shaping requirements detract greatly from an aircraft's aerodynamic properties. The F-117 has poor aerodynamics, is inherently unstable, and cannot be flown without a fly-by-wire control system.&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to know what are the impacts of such &lt;a href=&quot;http://en.wikipedia.org/wiki/Stealth_technology#Vehicle_shape&quot; rel=&quot;nofollow noreferrer&quot;&gt;planform alignment&lt;/a&gt; on planes capabilities, and how does a passive stealth shaping, using a small number of surface angles, compare to a &quot;5th generation fighter&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a different question than &lt;a href=&quot;https://aviation.stackexchange.com/questions/1798/do-similar-angles-on-a-plane-make-it-more-stealthy&quot;&gt;Do similar angles on a plane make it more stealthy?&lt;/a&gt;&quot; I'm looking for the advantages and disadvantages of using &lt;a href=&quot;http://en.wikipedia.org/wiki/Stealth_technology#Vehicle_shape&quot; rel=&quot;nofollow noreferrer&quot;&gt;planform alignment&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1696" LastEditDate="2018-04-20T14:35:47.843" LastActivityDate="2018-04-20T14:35:47.843" Title="What trade-offs are being made in the design of the planform alignment of stealth aircraft?" Tags="&lt;wing&gt;&lt;fighter&gt;&lt;jet&gt;&lt;stealth&gt;&lt;f-22&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15343" PostTypeId="2" ParentId="15235" CreationDate="2015-06-02T21:24:30.633" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/Convair_B-36_Peacemaker#Addition_of_jet_propulsion&quot; rel=&quot;nofollow&quot;&gt;B-36 Peacemaker had 6 radial engines, driving 6 propellers, AND 4 jet engines in 2 nacelles&lt;/a&gt;.  The jet engines were used for takeoff and for &quot;dash&quot; over a target.  The jets were turned off during cruise because they used considerably more fuel than the piston engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such, they HAVE made propeller/jet hybrid aircraft in the past, though not electric.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You probably want to feather the propellers and kill the electric motors.  If the props can only drive you to 250 MPH, leaving them windmilling in the slipstream when the jets are running will add drag, which will only serve to hurt your cruise speed and/or increase your fuel consumption.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They only work in conjunction as speed BELOW what your props can drive (eg 250 MPH, in your example).  Beyond that, if it's speed you're after, you're better off without the props.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At speeds above what the props can deliver, they're essentially small windmills.  And not very efficient ones at that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;See 2.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now, what WOULD be helpful as a &quot;hybrid&quot; aircraft would be a gasoline engine, turning a prop, with an electric motor added between the engine and the prop.  The electric motor could supply extra power during takeoff and function as a generator/dive brake on the prop during descent.  In the event the gasoline engine failed, the prop/electric motor assembly could be declutched from the gasoline engine, providing you with temporary power to maneuver around and land safely.  Gasoline engines in aircraft tend to be very reliable, but when they DO fail during take-off or landing, the most vulnerable parts of the flight, the results tend to be catastrophic.  As such, the gasoline/electric hybrid would be of no use during cruise but it MIGHT improve the safety factor during the most vulnerable parts of the flight.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastActivityDate="2015-06-02T21:24:30.633" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15344" PostTypeId="5" CreationDate="2015-06-02T21:28:30.680" Score="0" Body="&lt;p&gt;The F-22A raptor is a military fighter plane. It is what is considered a &amp;quot;5th generation fighter plane&amp;quot; It was invented by the United States Air Force military in 7 September 1997. They currently cost $412 million per aircraft.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="849" LastEditorDisplayName="user8732" LastEditDate="2020-12-12T10:48:16.577" LastActivityDate="2020-12-12T10:48:16.577" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15345" PostTypeId="4" CreationDate="2015-06-02T21:28:30.680" Score="0" Body="For questions about the Lockheed Martin F-22 Raptor fighter jet." OwnerDisplayName="user8732" LastEditorUserId="33692" LastEditorDisplayName="user8732" LastEditDate="2020-12-12T10:49:33.207" LastActivityDate="2020-12-12T10:49:33.207" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15346" PostTypeId="5" CreationDate="2015-06-02T22:53:36.507" Score="0" Body="&lt;p&gt;Posts migrated from other sites don't bring any tags along with them, so this tag is added in their place.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1696" LastEditDate="2015-06-03T19:18:55.453" LastActivityDate="2015-06-03T19:18:55.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15347" PostTypeId="4" CreationDate="2015-06-02T22:53:36.507" Score="0" Body="This post was probably migrated from another site and needs to have some relevant tags added!" OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2015-06-03T19:18:55.453" LastActivityDate="2015-06-03T19:18:55.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15348" PostTypeId="2" ParentId="14647" CreationDate="2015-06-02T23:36:18.980" Score="8" Body="&lt;p&gt;The 777-300ER locks the gear bogey in the horizontal position during takeoff making it considerably more difficult to tailstrike (Boeing said they hit the ground 12 times during testing with the -300, but only got within 18 inches on the -300ER).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jY9Ix.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Singapore-Airlines/Boeing-777-312-ER/1165806/L/&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See these documents: &lt;a href=&quot;https://i.stack.imgur.com/jY9Ix.jpg&quot;&gt;1&lt;/a&gt;, &lt;a href=&quot;http://www.airliners.net/photo/Singapore-Airlines/Boeing-777-312-ER/1165806/L/&quot;&gt;2&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-06-02T23:36:18.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15349" PostTypeId="1" AcceptedAnswerId="15362" CreationDate="2015-06-02T23:56:06.947" Score="9" ViewCount="4916" Body="&lt;p&gt;There are many different types passenger planes, but is there a optimal wing angle for these planes, that improves the plane's take off speed for example, or the fuel efficiency&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 747 has a wing seep angle of 37.5 degrees, the Airbus A380 has a wing sweep angle of 33.5 degrees. These are two of the largest planes in the world. So is the optimal range for a wing sweep angle between 33.5 and 37.5 degrees, or are there certain regulations stating different sweep back angles that a passenger airliner can use.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="19" LastEditDate="2016-07-04T11:03:41.923" LastActivityDate="2017-07-29T12:03:40.190" Title="What is the optimal wing sweep angle for a passenger airliner?" Tags="&lt;wing&gt;&lt;airbus-a380&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15351" PostTypeId="1" AcceptedAnswerId="15352" CreationDate="2015-06-03T01:33:18.503" Score="5" ViewCount="872" Body="&lt;p&gt;With computer-based fluid simulation already being extremely realistic (and likely faster and cheaper than physical wind tunnels), are they, anywhere, completely replacing physical wind tunnels? If not, is this planned anywhere, or even possible?&lt;/p&gt;&#xA;" OwnerUserId="8736" LastEditorUserId="1696" LastEditDate="2015-06-05T20:15:16.553" LastActivityDate="2015-06-05T20:15:16.553" Title="Will wind tunnel modelling ever be completely replaced by computer models?" Tags="&lt;aerodynamics&gt;&lt;wind-tunnel&gt;" AnswerCount="2" CommentCount="12" ClosedDate="2015-06-03T13:35:54.380" ContentLicense="CC BY-SA 3.0" />
  <row Id="15352" PostTypeId="2" ParentId="15351" CreationDate="2015-06-03T01:58:17.780" Score="4" Body="&lt;p&gt;The thing about computer models is that they are just that; models. They can only approximate the actual behavior we see in the real world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Computer models are good for trying many different ideas and making predictions. It can be faster to create a new computational test than to make a physical model for a wind tunnel. But very detailed fluid dynamics calculations require large amounts of computing power, and this takes time and money as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind tunnels can give much more detailed and accurate information, and are useful for validating the results given by the computers. The results don't always match, which means that the computer models must be revised. This is where wind tunnels are still very useful. They can test an entire airplane in actual flow, where computing that detail across the whole aircraft would require long computations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although a wind tunnel is also only a model of real conditions, it provides an actual body in actual flow conditions, which means the results can correlate much more closely to the real conditions being tested. Computational analysis is limited by assumptions, the chosen modeling method, and computational power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until computing power reaches the point where it can run models that will truly match a wind tunnel's accuracy and detail, there will still be a need to use wind tunnels to provide data.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-06-03T15:07:25.553" LastActivityDate="2015-06-03T15:07:25.553" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15354" PostTypeId="1" AcceptedAnswerId="15364" CreationDate="2015-06-03T04:52:44.433" Score="6" ViewCount="2951" Body="&lt;p&gt;Given the fact that podded engines on the wings of airplanes cause much drag (and thereby contribute to a lot of loss of efficiency), why do airliners still prefer podded turbojet engines over turbojet engines fitted inside the fuselage (or inside the wing) ?&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;This question is not regarding &amp;quot;What is the role of Pylons in a podded jet engine&amp;quot;, but this is about &amp;quot;Why podded engines in the first place?&amp;quot;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-10-31T21:55:19.710" Title="Why are podded engines preferred over engines fitted inside the fuselage or wing?" Tags="&lt;jet-engine&gt;&lt;multi-engine&gt;&lt;drag&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="15355" PostTypeId="5" CreationDate="2015-06-03T04:53:46.850" Score="0" Body="&lt;p&gt;Placing engines on the wing provides beneficial wing bending relief in flight. The further the engines are away from the fuselage the greater the wing bending relief so engines buried in the wing root provide little relief. Almost all modern large jet airplanes use engines in pods located a significant distance from the wing root for substantial wing bending relief. The pods are in front of the wing to help avoid flutter of the wing which, in turn, allows a much lighter wing structure. Locating the pod below the wing provides each engine with air undisturbed by the fuselage or wing. The wing also blocks some engine noise from reaching the aircraft cabin.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T11:52:51.750" LastActivityDate="2015-06-03T11:52:51.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15356" PostTypeId="4" CreationDate="2015-06-03T04:53:46.850" Score="0" Body="A podded engine is a jet engine in a pod, typically attached below the wing or to the tail of the aircraft. The pod itself is called a nacelle." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T11:52:31.220" LastActivityDate="2015-06-03T11:52:31.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15357" PostTypeId="2" ParentId="15311" CreationDate="2015-06-03T04:54:27.233" Score="10" Body="&lt;p&gt;It's going to be hard to provide a hard answer, because it would vary from aircraft to aircraft.  But, let's take a &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737&quot;&gt;Boeing 737&lt;/a&gt; as a reference, simply because it's quite common, and small(ish), so one would assume it would be more likely to survive than a larger jetliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.iacusn.org/schools/reprints/07aug_stowell.pdf&quot;&gt;this guide on executing a loop (pdf)&lt;/a&gt;, you want to maintain roughly 3.5 positive g's when executing a loop (and this is best case, in the hands of an experience pilot.)  Bearing that in mind, &lt;a href=&quot;http://www.b737.org.uk/limitations.htm&quot;&gt;Boeing lists the maximum positive g's for a Boeing 737 at +2.5g&lt;/a&gt; (with flaps retracted).  Which leaves us an entire unit of earth's gravity short of being able to safely execute the maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in the case of the 737, the answer is a &lt;em&gt;resolute&lt;/em&gt; &lt;strong&gt;no&lt;/strong&gt;.  And I think it's safe to assume that most commercial aircraft are not much stronger (In fact, in doing some more checking the &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_747-400&quot;&gt;Boeing 747-400&lt;/a&gt; and the &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320_family&quot;&gt;Airbus A320&lt;/a&gt; have the exact same g load characteristics, &lt;a href=&quot;http://www.tc.faa.gov/its/worldpac/techrpt/ar04-44.pdf&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.satavirtual.org/fleet/A320LIMITATIONS.PDF&quot;&gt;here&lt;/a&gt; respectively.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we can probably assume that no commercial jetliner can &lt;em&gt;safely&lt;/em&gt; handle a loop.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-06-03T05:04:51.340" LastActivityDate="2015-06-03T05:04:51.340" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15358" PostTypeId="5" CreationDate="2015-06-03T04:54:40.453" Score="0" Body="&lt;p&gt;In more mathematical or scientific terms, it is a measure of the extent to which input is well used for an intended task or function (output). It often specifically comprises the capability of a specific application of effort to produce a specific outcome with a minimum amount or quantity of waste, expense, or unnecessary effort. Efficiency of course refers to very different inputs and outputs in different fields and industries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Efficiency is very often confused with effectiveness. In general, efficiency is a measurable concept, quantitatively determined by the ratio of useful output to total input. Effectiveness is the simpler concept of being able to achieve a desired result, which can be expressed quantitatively but doesn't usually require more complicated mathematics than addition. Efficiency can often be expressed as a percentage of the result that could ideally be expected, for example if no energy were lost due to friction or other causes, in which case 100% of fuel or other input would be used to produce the desired result. This does not always apply, not even in all cases in which efficiency can be assigned a numerical value, e.g. not for specific impulse.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T11:52:46.987" LastActivityDate="2015-06-03T11:52:46.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15359" PostTypeId="4" CreationDate="2015-06-03T04:54:40.453" Score="0" Body="Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without waste." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T11:52:39.310" LastActivityDate="2015-06-03T11:52:39.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15360" PostTypeId="2" ParentId="15349" CreationDate="2015-06-03T05:04:45.437" Score="2" Body="&lt;p&gt;No, there is no specific sweep angle which serves best for improving the sweep of the plane wing. This is because the sweep is NOT introduced just for improving the fuel efficiency of the plane, but the following factors are also considered by commercial airliners while finalizing the design sweep of a wing:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Design Mach Number&lt;/li&gt;&#xA;&lt;li&gt;What extent of longitudinal stability the airplane manufacturer&#xA;expects out of the wing (This would depend upon the final usage of&#xA;the plane)&lt;/li&gt;&#xA;&lt;li&gt;How much part of the longitudinal stability the manufacturer expects from the Dihedral, and the rest from the sweep back.&lt;/li&gt;&#xA;&lt;li&gt;Is the manufacturing of such a sweep back (and dihedral) wing&#xA;feasible enough, and if not, what additional resources need to be&#xA;invested to manufacture this?&lt;/li&gt;&#xA;&lt;li&gt;What kind of control system (Fly by wire or not) is being used?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;After optimizing on all the above said factors (and the fuel efficiency), the aircraft is modeled under CFD to get results, and then it is decided what sweep back to use&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T07:55:38.263" LastActivityDate="2015-06-03T07:55:38.263" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15362" PostTypeId="2" ParentId="15349" CreationDate="2015-06-03T06:47:53.713" Score="8" Body="&lt;p&gt;Generally, sweep makes the wing less efficient in creating lift and complicates structural design. Therefore, aircraft designers try to use as little sweep as they can get away with. However, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1726/why-do-some-military-aircraft-use-variable-sweep-wings&quot;&gt;sweep delays the&lt;/a&gt; onset of &lt;a href=&quot;https://aviation.stackexchange.com/questions/4992/why-are-swept-wings-better-for-breaking-the-sound-barrier&quot;&gt;compressibility effects&lt;/a&gt; and allows jet aircraft to improve their maximum transport performance (the product of speed and payload).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2360/what-are-the-advantages-of-a-forward-swept-wing-over-a-rearward-swept-wing&quot;&gt;Forward and backward sweep&lt;/a&gt; both help to fly faster, but backward sweep is preferred because it makes stalling less dangerous, improves &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability&quot;&gt;directional stability&lt;/a&gt; and allows to make the wing lighter. The shortest take-off distance will be achieved with zero sweep - if it were not for the need to limit compressibility effects, sweep would only be used in tailless aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main factor for choosing wing sweep is the desired &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85&quot;&gt;cruise Mach number&lt;/a&gt;, and Mach 0.85 has become the de-facto standard. Other factors are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Relative wing thickness: A thicker wing needs more sweep, because thickness adds its own compressibility effects.&lt;/li&gt;&#xA;&lt;li&gt;Maximum local Mach number of the airfoil where recompression is shock-free: So-called &lt;a href=&quot;https://aviation.stackexchange.com/questions/13453/what-is-the-actual-air-speed-over-and-under-a-wing-due-to-bernoullis-principle&quot;&gt;supercritical airfoils&lt;/a&gt; help to reduce sweep, and older designs (before the A310) had generally more sweep because their critical Mach number would had been lower at equal sweep.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Regulations have nothing to do with it, only engineering determines the sweep angle. Since the design cruise Mach number is &lt;a href=&quot;https://aviation.stackexchange.com/questions/3748/why-1st-and-2nd-class-but-not-fast-or-slow-airplanes&quot;&gt;quasi-fixed&lt;/a&gt; at Mach 0.85 for long-range airliners, the sweep angle of different aircraft is very similar. Regional jets normally fly a little slower to improve fuel efficiency, and their sweep angle is less than that of their big, long-range cousins.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-07-29T12:03:40.190" LastActivityDate="2017-07-29T12:03:40.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15363" PostTypeId="1" CreationDate="2015-06-03T08:00:50.270" Score="3" ViewCount="788" Body="&lt;p&gt;I think my question/situation is a little bit of rare so I start this question and want to hear from you experience pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a 30+ migrant from China working as a software engineer for 10 years. Now I use my weekends taking flight training for Private Pilot Licence in Sydney. Currently I don't see any big problem with my training and probably in next couple of weeks I will have my first Solo. What concerns me is my past experience. I can say I'm rather a good programmer and writing code for computer(iPhone) is really different from driving or flying. My flight instructor tend to say (and I agree) I always fly with the exact numbers rather than make necessary adjustment according to situation outside. So I guess with the past 10 years indoor in-front-of-keyboard office life/experience. The more you get your life/experience aligned with computer/coding, the harder you could get out of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's worse is I don't have any driving experience until two months ago I started to practice for my Australian driver's licence. Now I have my licence issued for one month and I still only drove four or five times with rented car. Though I love public transportation and I'm not that declined to own a car, now I start to thinking about the benefit of driving experience for my flight training. At least driving skills are accumulated with &quot;hours&quot; (which is the same as flying) and it will get me out of computer world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you have any suggestion or advice on this? Thanks for reading and replying. Cheers~&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. if possible, my target is CPL one day.&lt;/p&gt;&#xA;" OwnerUserId="404" LastActivityDate="2015-06-03T14:47:26.680" Title="Will driving experience benefit flight training?" Tags="&lt;flight-training&gt;" AnswerCount="4" CommentCount="2" ClosedDate="2015-06-03T13:02:30.197" ContentLicense="CC BY-SA 3.0" />
  <row Id="15364" PostTypeId="2" ParentId="15354" CreationDate="2015-06-03T08:23:33.107" Score="9" Body="&lt;p&gt;Most important factor affecting drag is frontal area. Almost all frontal area of the engine pod is the intake and it has to have the size it does to collect the air the engine needs. So there is not so much drag to be saved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beside that, embedding the engine in wing roots like &lt;a href=&quot;http://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow noreferrer&quot;&gt;De Havilland Comet&lt;/a&gt; did has many disadvantages, most of which also apply to the central engine of three-engined jets (B727, DC-10):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing root carries the weight of the aircraft, so weakening it by embedding the engine is design and construction complication.&lt;/li&gt;&#xA;&lt;li&gt;Access for maintenance is difficult. Engines need a lot of maintenance and sometimes need to be replaced.&lt;/li&gt;&#xA;&lt;li&gt;Uncontained failure is more dangerous (see &lt;a href=&quot;http://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow noreferrer&quot;&gt;UA232&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;There is not much structure to damp vibration, so it is awfully noisy.&lt;/li&gt;&#xA;&lt;li&gt;And last but not least, modern high-bypass turbofans are huge. They would not fit in the wing anyway.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And reasons for not attaching the engines directly to the fuselage or wing are already mentined in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12109/why-do-we-use-pylons-to-mount-engine-on-jet-airliners&quot;&gt;Why do we use pylons to mount the engines on jetliners?&lt;/a&gt;. Mainly, the inlet needs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Free space around it from which it can draw air at slow speed.&lt;/li&gt;&#xA;&lt;li&gt;Free space around it to which it can spill the excess air at high speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And the engines mounted forward of wing actually improve the distribution of cross-sectional area according to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;Whitcomb area rule&lt;/a&gt; and they dampen flutter, so the wing can be slightly less stiff and thus slightly lighter.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2018-10-31T21:55:19.710" LastActivityDate="2018-10-31T21:55:19.710" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15365" PostTypeId="2" ParentId="15363" CreationDate="2015-06-03T08:24:10.083" Score="1" Body="&lt;p&gt;Driving experience helps in flying only by &quot;curing&quot; your reflexes. Nothing else. You can have no driving experience and still be a good pilot, but there is a thing called &quot;Pilot Aptitude&quot;. Some people are good at it, some people are not. This does not come from how experienced a driver you are, but comes intrinsically from the fact &quot;How good you are&quot;. Many air-forces across the world have this test, and it is often claimed that one cannot gain this aptitude just by flying more. You need to have this aptitude, and after that you can improve your flying skills by having more experience and practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indian Air Force conduccts &lt;a href=&quot;http://en.wikipedia.org/wiki/Services_Selection_Board#Pilot_Aptitude_Battery_Test&quot; rel=&quot;nofollow&quot;&gt;PABT&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-03T08:54:09.253" LastActivityDate="2015-06-03T08:54:09.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15366" PostTypeId="2" ParentId="15341" CreationDate="2015-06-03T08:41:14.897" Score="2" Body="&lt;p&gt;To understand the functioning of planform alignment in befitting the fifth generation air-crafts in increasing their stealth, one first need to understand how Radars work:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Radar transmits a radio wave signal.&lt;/li&gt;&#xA;&lt;li&gt;This signal when comes in contact with a surface (of an aircraft), it is reflected back. This reflection is a mixture of &lt;strong&gt;Specular&lt;/strong&gt; and &lt;strong&gt;Diffused&lt;/strong&gt; reflection. &lt;/li&gt;&#xA;&lt;li&gt;The radar then after receiving the reflected signal, measures the speed (by computing the shift in the time period taken by the wave to be received over a period of time), and size (by computing the intensity of the reflected wave) of the air-craft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But there is a problem, since the radar needs to get back its own transmitted wave back, if it is reflected off the surface of the plane only at a specific angle (specular reflection), then the receiver of the radar needs to be at specific places to receive the reflected wave. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern planes utilize this shortcoming of the radar by letting the incoming radar signal pass through them (using plan-form alignment), which then greatly reduces the reflected signal. The reduced reflected signal would be seen as an incoming signal of very low strength (intensity) by the radar, which then reads the size of the incoming air-craft as a very small object. This is called &lt;strong&gt;Stealth&lt;/strong&gt;. The air-crafts also use special paints and composite coverings on the surface to again reduce the intensity of the reflected wave, to reduce the percieved size of the air-craft by the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shortcomings of such radars are removed by using radars such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Airborne_Warning_and_Control_System&quot; rel=&quot;nofollow&quot;&gt;AWACS&lt;/a&gt;, which is moving radar and can receive too directional signals (Specular reflection). Or, using radars such as &lt;a href=&quot;http://en.wikipedia.org/wiki/Active_electronically_scanned_array&quot; rel=&quot;nofollow&quot;&gt;AESA&lt;/a&gt;, which scans a large portion of area around it without having any moving parts.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-03T08:41:14.897" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="15367" PostTypeId="2" ParentId="15363" CreationDate="2015-06-03T09:51:58.157" Score="2" Body="&lt;p&gt;My experience is the other way around: Learning to fly improved my driving skills. This mainly in the field of trip planning and discipline of execution. Remember, with a car you can always pull to the right (in Australia to the left) and stop. With an airplane you do not have this luxury, so you learn to think ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are comfortable with public transport, forget to get a car. Driving is expensive. But try to get behind the wheel every now and then to build up experience.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-06-03T09:51:58.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15368" PostTypeId="2" ParentId="15363" CreationDate="2015-06-03T10:02:01.610" Score="7" Body="&lt;p&gt;I don't think driver training is beneficial to flight training, the physical acts of driving and flying are too dissimilar. Driving is a handy skill to have for sure, it's usually much easier to get to the airfield for one thing, it's not going to translate to flying though. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for flying the numbers you are falling back on what you are good at: attention to technical detail. Attention to technical detail is a very good thing in flying - having a plan and rehearsing for emergencies can save you neck. What your instructor may be telling you is that you need to focus your attention to &lt;strong&gt;other&lt;/strong&gt; details. You may be spending too much time looking at your instruments and not enough looking outside. I did this at first because I had spent a lot of time playing flight simulators and I'm also in IT and spend a lot of time looking at displays in front of my face. The cure is simple: force yourself to get in the good habits of looking outside the aircraft and developing situational awareness. You can only get that through flying practice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It sounds like you are concerned that you don't have a sort of instinctual &quot;feel&quot; for flying. Everyone has a different set of aptitudes, some people are better at certain aspects of flying than others. If there's an area you are weak in then focus your training and practice on developing it into a strength. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-06-03T10:02:01.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15369" PostTypeId="2" ParentId="15335" CreationDate="2015-06-03T10:18:37.193" Score="20" Body="&lt;p&gt;When a large commercial aircraft touches down, it is &lt;strong&gt;not&lt;/strong&gt; committed to stopping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it &lt;strong&gt;is&lt;/strong&gt; committed to stopping when the &lt;strong&gt;thrust reversers are selected&lt;/strong&gt;. This is because they take different time to stow and adding power while stowing would likely cause significant asymmetric thrust. And even if they don't, they take their time to stow and you are unlikely to have enough speed and runway when they finally do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When thrust reverses are not selected, the pilots of course have to consider whether it is more likely that they can stop or lift-off again on the remaining runway. And they sometimes do choose to lift off. There are many incidents where planes went around after tail or even wing strikes or bounces as it's often easier to get the plane under control by adding power. But once thrust reversers are selected, stowing them again means loosing a lot of time and is risky, so go-around is considered out of question afterwards.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-04T13:49:07.077" LastActivityDate="2015-06-04T13:49:07.077" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15370" PostTypeId="1" AcceptedAnswerId="15376" CreationDate="2015-06-03T12:24:49.560" Score="7" ViewCount="413" Body="&lt;p&gt;I've got a very specific question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a fire sensor perceives a fire, does it wait &lt;strong&gt;20 or 60 seconds&lt;/strong&gt; before giving the alarm?&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="19" LastEditDate="2016-07-04T11:04:57.780" LastActivityDate="2016-07-04T11:04:57.780" Title="What is the time before an alarm is given after a fire sensor perceives a fire?" Tags="&lt;aircraft-systems&gt;&lt;fire&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15371" PostTypeId="2" ParentId="15363" CreationDate="2015-06-03T12:37:17.693" Score="3" Body="&lt;p&gt;From my subjective experience, training pilots without driving experience is not a big deal, as long as it not an indicator of being uninterested in things technical. (Remember, tons of people start flying gliders in their teens, before ever having driven a car).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you are describing is the typical path of the flight student, and from the fact that you are concerned with making good progress: a motivated flight student.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without training and experience, you can not expect yourself to &lt;em&gt;intuitively&lt;/em&gt; know what to do when you are &quot;too low on base&quot;. In fact, you can not even expect yourself to even &lt;em&gt;know&lt;/em&gt; that you are &quot;too low on base&quot;. The only way to compensate for this, in the beginning of your training is by doing things &quot;by the numbers&quot; (ie, knowing what height you should be over the blue house etc) (sort of like following an algorithm).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the most common (once again my subjective perspective) hurdle seen in new pilots with plenty of flight simulator experience is underestimating the importance of outside visual references (in practical terms: they don't trust their own ability to judge their attitude looking at the outside horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an educating experiment: Ask your flight instructor to oscillate the aircraft in pitch +/- 1 degrees while you look only at the artificial horizon, then have the instructor repeat it, while you look outside, at the natural horizon, and make your own conclusions as to which is &quot;the better&quot; instrument. :)&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-06-03T14:47:26.680" LastActivityDate="2015-06-03T14:47:26.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15372" PostTypeId="2" ParentId="15239" CreationDate="2015-06-03T12:48:05.503" Score="5" Body="&lt;p&gt;The F-16 Fly-By-Wire (and therefore most likely also the F-18) does actually not automatically correct for left/right CG shift due to stores load. The pilot manually has to adjust the electronic trim control (which Dan Hulme already described) to account for it. However the CG shift from releasing of one missile is relatively minimal, and would require only a tiny trim adjustment. Bombs or larger air to ground missiles is a whole different story.&lt;/p&gt;&#xA;" OwnerUserId="8743" LastActivityDate="2015-06-03T12:48:05.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15373" PostTypeId="2" ParentId="15351" CreationDate="2015-06-03T12:59:58.867" Score="2" Body="&lt;p&gt;At the end we are taking about modeling, where we are having computer modeling and on the other side we have hardware modeling. When we are talking about modeling we have 3 levels of modelization:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Geometry and external conditions modeling: approximation made of the geometry and the external conditions defined in the problem. This includes the supports created in wind tunnel for example.&lt;/li&gt;&#xA;&lt;li&gt;Numerical discretization: how the external flow domain is discretized numerically.&lt;/li&gt;&#xA;&lt;li&gt;Turbulence modelling: how the external physics is represented (Euler, RANS, LES...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Hardware modelling is only affected by the first parameter, for example, Reynolds number is not the same in many wind tunnel. Tests and the external conditions are replaced by walls. In fact, in the area of geometry and external conditions, numerical simulation is far more advanced than current WTT state of the art.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Numerical discretization is only present in numerical simulation, and here just by adding brute force you can reduce is as much as you can. Current state of the art is not allowing to reduce it to 0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence modelling is the key for numerical simulation. Current models used in the industry are not able to properly model some extreme areas (high separated flows for instance) and the current most promising techniques (&lt;a href=&quot;http://www.cfd-online.com/Wiki/Direct_numerical_simulation_(DNS)&quot; rel=&quot;nofollow&quot;&gt;DNS&lt;/a&gt;, &lt;a href=&quot;http://www.cfd-online.com/Wiki/Les&quot; rel=&quot;nofollow&quot;&gt;LES&lt;/a&gt;) are highly demanding in computational time, increase constrains in the discretization area and, more importantly, have not been proved properly on industrial relevant cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that current numerical simulation is ahead to wind tunnel (hardware simulation) in the area of geometry and external conditions, but mainly weak on the area of turbulence modelling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current situation is that wind tunnel has been replaced by numerical simulation in the area where turbulence modelling is not highly demanded by accuracy demands or physics complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for being able to model some part of the physics the industry can only go hardware testing (wind tunnel).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going more precisely to your question, numerical modelling will replace hardware testing when is able to solve the gap in turbulence modelling. The current situation as I described above, there are some approached promising to the future, but we will be able to evaluate if those approaches (DNS, LES) are able to close the gap when an application of a full aircraft is made. Currently, that is foreseen in 20 years time (I don't have reference sorry...), my point of view is that 20 years is optimistic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So answering your question is, we can answer the question yet, we need 20 years further to be able to answer you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally I would like to make a point in terms of costing. It is clear than creating a model in hardware testing (a phyisical model) is much expensive than a model in numerical testing (a mesh). However, a model in a wind tunnel has a huge productivity once in a wind tunnel (a new simulation point in less than a second), simulation takes hours once the model is ready. However, numerical simulation is reducing each year the cost of its model much more faster than wind tunnel. Still for some applications with high productivity of points needed, wind tunnel is far cheaper.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-06-03T12:59:58.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15375" PostTypeId="1" AcceptedAnswerId="15392" CreationDate="2015-06-03T13:09:49.400" Score="11" ViewCount="4076" Body="&lt;p&gt;How does the 'double bubble' fuselage cross-section of the &quot;&lt;a href=&quot;http://www.nasa.gov/content/the-double-bubble-d8-0/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Double Bubble D8&lt;/a&gt;&quot; aircraft (developed by MIT for NASA) help improve overall efficiency by around 70%?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MRoju.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MRoju.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Image credit: NASA/MIT/Aurora Flight Sciences&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="62" LastEditDate="2017-05-19T17:18:36.290" LastActivityDate="2017-05-19T17:18:36.290" Title="How is the D8 Double Bubble aircraft by NASA so efficient?" Tags="&lt;aircraft-performance&gt;&lt;efficiency&gt;&lt;nasa&gt;&lt;double-bubble-d8&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15376" PostTypeId="2" ParentId="15370" CreationDate="2015-06-03T13:18:11.377" Score="10" Body="&lt;p&gt;The fire sensor's time to give the alarm is customizable depending upon the fire safety alarm being used. Two widely used types of continuous-loop systems are the thermistor type detectors, such as the Kidde and the Fenwal systems, and the pneumatic pressure detector, such as the Lingberg system. (Lindberg system is also known as Systron-Donner and, more recently, Meggitt Safety Systems.). A typical delay of &lt;strong&gt;10 Seconds&lt;/strong&gt; is quite common. Here is the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch17.pdf&quot;&gt;Source&lt;/a&gt; for your further reading&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-03T13:18:11.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15377" PostTypeId="2" ParentId="15207" CreationDate="2015-06-03T13:29:47.700" Score="7" Body="&lt;p&gt;I'm surprised there has been no mention of this.  One very common acronym is the FEVER check:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;F: fluctuating fluids (hydraulic, oil, etc.)&#xA;E: excessive EGT, ITT, FTIT, etc.&#xA;V: vibration&#xA;E: erratic operation&#xA;R: roughness&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-03T13:29:47.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15378" PostTypeId="2" ParentId="15375" CreationDate="2015-06-03T13:37:33.170" Score="4" Body="&lt;p&gt;(&lt;a href=&quot;http://www.nasa.gov/topics/aeronautics/features/future_airplanes.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.nasa.gov/topics/aeronautics/features/future_airplanes.html&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The engines require less power, it requires less runway to take off&#xA;on (about 5000 ft)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;flying shorter and more direct routes, for cost-efficiency.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Reliance on promised advancements in air traffic management such as&#xA;the use of automated decision-making tools for merging and spacing&#xA;enroute and during departure climbs and arrival descents.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;overall it essentially improves most aspects of the aircraft, (I have oinly listed a few things, their are loads more on the NASA website)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/b0I4K.jpg&quot; alt=&quot;D8 bubble aircraft&quot;&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorDisplayName="user8732" LastEditDate="2015-06-03T13:38:53.803" LastActivityDate="2015-06-03T13:38:53.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15379" PostTypeId="2" ParentId="15375" CreationDate="2015-06-03T13:49:28.967" Score="3" Body="&lt;p&gt;Their &lt;a href=&quot;http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf&quot; rel=&quot;nofollow&quot;&gt;presentation&lt;/a&gt; on page 87 specifically covers reasons for the fuselage design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional lift and more cabin room in a smaller fuselage seem to be the main reasons they give.  But there are a lot of other details in the presentation too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But note: the fuselage shape is only part of the overall claimed efficiency improvements.  There are many other features such as a lower cruise speed, reduced sweepback of the wings leading to weight saving, etc.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2015-06-03T13:55:36.973" LastActivityDate="2015-06-03T13:55:36.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15380" PostTypeId="2" ParentId="489" CreationDate="2015-06-03T14:04:16.447" Score="6" Body="&lt;p&gt;A &lt;em&gt;barrel&lt;/em&gt; roll, when &lt;em&gt;properly&lt;/em&gt; executed, does not put the aircraft through any unusual stress and is possible with almost any aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However it is only true if it is &lt;em&gt;properly&lt;/em&gt; executed. Make a small mistake and you can easily put more stress on the aircraft than it can handle, put it to a spin due to excessive side-slip (barrel roll is cross-controlled manoeuvre), starve the engines of fuel (if you let it slip into negative G) or simply loose spatial orientation (especially in older aircraft with mechanical gyroscope that would tumble) and then you'll end up like &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20100214-0&quot; rel=&quot;noreferrer&quot;&gt;these two pilots in Cessna 550B Citation in Germany in 2010&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-03T14:04:16.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15381" PostTypeId="2" ParentId="15375" CreationDate="2015-06-03T14:40:42.803" Score="7" Body="&lt;p&gt;Looking at &lt;a href=&quot;http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf&quot;&gt;MIT's presentation&lt;/a&gt;, more specifically pages 13 - 15, they're counting on the fuselage being a &lt;a href=&quot;http://en.wikipedia.org/wiki/Lifting_body&quot;&gt;lifting body&lt;/a&gt;, among other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most aircraft, the fuselage encompasses the passenger cabin, cargo cabin, fuel tanks etc. and is designed to impose as little drag as possible in the process.  With a lifting body, the fuselage actually provides lift, instead of just adding minimal drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept is also counting on&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;cleaner aerodynamics&lt;/li&gt;&#xA;&lt;li&gt;advanced, lightweight materials&lt;/li&gt;&#xA;&lt;li&gt;higher-efficiency engines&lt;/li&gt;&#xA;&lt;li&gt;less wing area&#xA;&lt;ul&gt;&#xA;&lt;li&gt;with the fuselage providing some lift, the lighter weight and less fuel needed for the projected mission, less wing area is needed&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All of these, in combination, provide the estimated 70% greater efficiency.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastActivityDate="2015-06-03T14:40:42.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15382" PostTypeId="1" AcceptedAnswerId="15386" CreationDate="2015-06-03T14:46:13.877" Score="3" ViewCount="2728" Body="&lt;p&gt;Broadly, Military and Civil are the only two categories in which the Pilots can be classified on the basis of the roles performed by them. What are the similarities and differences in tasks performed by them?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-05T12:48:36.690" LastActivityDate="2020-08-09T02:41:03.693" Title="How similar/different are the roles performed by Military and Civil pilots?" Tags="&lt;commercial-aviation&gt;&lt;military&gt;&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15383" PostTypeId="2" ParentId="14305" CreationDate="2015-06-03T15:04:07.790" Score="11" Body="&lt;p&gt;Propeller efficiency is mentioned a lot here on Aviation SE, but lacks a good explanation. Here we go:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A propeller accelerates the air of density &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; which is flowing through the propeller disc of diameter &lt;span class=&quot;math-container&quot;&gt;$d_P$&lt;/span&gt;. This can be idealized as a stream tube going through the propeller disc. This stream tube starts with air at ambient speed and a wide diameter d&lt;span class=&quot;math-container&quot;&gt;$_0$&lt;/span&gt;. As the suction ahead of the propeller accelerates the air in the streamtube, it starts to speed up and the stream tube contracts. In the propeller plane we witness a jump in pressure p: Here, energy is added to the flow, so Bernoulli does not apply momentarily. Past the propeller the air in the stream tube accelerates further and the tube contracts to the diameter d&lt;span class=&quot;math-container&quot;&gt;$_1$&lt;/span&gt; when the pressure inside has dropped to the ambient pressure (dashed line in the pressure graph below):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sfxUA.png&quot; alt=&quot;Section of airstream through propeller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air speed ahead is &lt;span class=&quot;math-container&quot;&gt;$v_0 = v_{\infty}$&lt;/span&gt; and the air speed aft of the propeller is &lt;span class=&quot;math-container&quot;&gt;$v_1 = v_0 + \Delta v$&lt;/span&gt;. The propeller effects a pressure change which sucks in the air ahead of it and pushes it out. Since the mass flow must be equal ahead and behind the propeller, the stream tube diameter is bigger ahead of the propeller and smaller downstream. In reality, there is no neat boundary between the air flowing through the propeller and that surrounding it, but for computing thrust this simplification works well if the airspeed is identical across the cross section of the propeller disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The efficiency &lt;span class=&quot;math-container&quot;&gt;$\eta$&lt;/span&gt; of thrust creation is the work done on the mass flow through the propeller &lt;span class=&quot;math-container&quot;&gt;$W = m\cdot\Delta v\cdot v_0$&lt;/span&gt; relative to the impulse change of the air &lt;span class=&quot;math-container&quot;&gt;$\Delta I = m\cdot\frac{v_1^2 - v_2^2}{2}$&lt;/span&gt;:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\eta^{opt} = \frac{2\cdot v_0}{v_1 + v_0} = \frac{v_{\infty}}{v_{\infty} + \frac{\Delta v}{2}} = \frac{1}{1 + \frac{\Delta v}{2\cdot v_{\infty}}}$$&lt;/span&gt;&#xA;This equation assumes that air is uniformly accelerated straight backwards. To be more precise, you need to add the swirl losses, since the air receives a rotational component &lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; from the propeller, spinning with the angular velocity &lt;span class=&quot;math-container&quot;&gt;$\Omega$&lt;/span&gt;, as well:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\eta^{opt}_{Prop} = \frac{1 - \frac{\Delta v\cdot \left({v_{\infty} + \frac{\Delta v}{2}}\right)}{d_P^2\cdot\Omega^2}}{1 + \frac{\Delta v}{2\cdot v_{\infty}}}$$&lt;/span&gt;&#xA;Still, we have not included friction losses yet and our prop spinner and engine nacelle are also not included. Now we must enter into a definition what propeller thrust is: Is it just the lift acting on the propeller blades in forward direction, or is it the remaining forward force after the additional drag of the airplane components in the slipstream of the propeller has been subtracted?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To avoid lengthy computations, &lt;a href=&quot;http://ufdc.ufl.edu/AA00009506/00001&quot; rel=&quot;nofollow noreferrer&quot;&gt;charts&lt;/a&gt; can be used where the efficiency is plotted over a range of parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To cut the discussion short: Generally it is safe to assume a top propeller efficiency of 0.85 (85%) with big, slowly spinning propellers (1000 to 1700 RPM). If the twist distribution along the blade does not match the local angle of attack distribution (say, if the propeller is optimized for high speed, but operated at slow airspeed, like during take-off), efficiency can easily drop to 0.7 (70%). Things become worse if the pitch of the blades is fixed. See below for a typical example of a variable pitch propeller. Each of the curves is for a different pitch setting, the x axis shows the advance ratio (the ratio between airspeed and circumferential speed; here off by a factor of 1/&lt;span class=&quot;math-container&quot;&gt;$\pi$&lt;/span&gt;), while the y axis shows the efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/U0gYH.jpg&quot; alt=&quot;Efficiency chart of a variable pitch propeller&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Efficiency chart of a variable pitch propeller. Source: McCormick B.W. Aerodynamics, Aeronautics &amp;amp; Flight Mechanics. John Wiley &amp;amp; Sons, Inc., 1979.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can be seen from the equations above is that it is more efficient to accelerate lots of air a little than to accelerate a little air by a lot. This means that small propellers on ungeared engines, spinning at high RPM, are at a distinct disadvantage; this is why Roskam assumes only 70% for them and only 80% for GA propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 90% you name has to my knowledge only been scratched at by some very efficient (slow, large, contra-rotating) propellers operating under ideal conditions. To play it safe, I would choose a slightly smaller number for them.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-12-16T13:07:12.693" LastActivityDate="2018-12-16T13:07:12.693" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="15384" PostTypeId="2" ParentId="15337" CreationDate="2015-06-03T15:31:18.893" Score="2" Body="&lt;p&gt;It depends on the missile and the shooting aircraft, but the short answer is, missiles are actually pretty dumb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're using sight lock off your helmet cuing system, it's likely you're using a short-range IR missile like a Sidewinder, ASRAAM or AA-11. While improvements have been made, they're still spoofable, so it's actually fairly likely that if another aircraft crossed the line of sight between you and the bandit, the missile would go off-track. Whether it would really &quot;lock&quot; onto the other aircraft is debatable; right up until you fire, your aircraft is feeding information into the seeker head of the missile to point it at the correct target, so the missile will usually leave the rail with a target in its seeker, and anything else passing through the seeker's field of vision will be moving relatively fast through the seeker's field, so unless it &quot;blinds&quot; the seeker head completely it's unlikely the missile will track the new target, though it may be unable to find its intended target again after an event like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At BVR distances, as Rhino Driver states, getting a reliable lock on an aircraft isn't as hard as figuring out whether that aircraft is friend or foe. At these ranges, radar missiles are used which require the aircraft to have a radar lock on the target (though &quot;lock-on after launch&quot; capability is available for many of these missiles), providing very specific information about the target's range, heading, speed and, given sufficient radar returns for the FCC to match the signature, even the type of aircraft (at just outside visual range, modern radar can be good enough to nail down make and model). However, confirming a target is hostile requires more than that (the US-allied Malaysian Air Force, for instance, flies Russian-supplied Su-30MKMs, while the Iranian Air Force technically has a few F-14s left in service from before the Embassy takeover).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To do that, NATO aircraft (and most other forces around the world by now) have IFF transponders; A radar lock (or even a scan) of sufficient strength will produce a return including a coded response; said code can be varied to prevent use of the same code by an enemy force. It's not dissimilar from civilian transponders, though the needs of civilian ATC and the military differ.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-03T15:31:18.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15385" PostTypeId="1" CreationDate="2015-06-03T15:36:31.430" Score="0" ViewCount="711" Body="&lt;p&gt;Statistical Analysis of A320 aircraft shows the Cl values to be as under: &lt;a href=&quot;https://i.stack.imgur.com/fiIzt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;cl_value&lt;/a&gt;. L is assumed to be 0.5*MaximumLandingWeight of A320 as the Aircraft is about to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Units used are: Flight Level(feet), rho(lb/feet^3, V(feet/s), for the sixth column, 1/2(rho.V^2.S.)&#xA; &lt;img src=&quot;https://i.stack.imgur.com/oVomW.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cruise Cl values are as under: &lt;img src=&quot;https://i.stack.imgur.com/BdqoA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When compared to cruise the CL during descent is very small. Is this an acceptable result?&lt;/p&gt;&#xA;" OwnerUserId="8709" LastEditorUserId="5694" LastEditDate="2015-06-04T08:55:05.803" LastActivityDate="2015-06-05T06:55:21.943" Title="What are the opimum values of Cl during descent?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aeroacoustics&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15386" PostTypeId="2" ParentId="15382" CreationDate="2015-06-03T15:58:39.217" Score="3" Body="&lt;p&gt;As mentioned Commercial should really be &quot;Civilian&quot; which includes Private and Commercial. Lets assume that military includes the various branches that employ pilots (Navy, Air Force, Marines etc). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end of the day everyone flies a plane... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A chunk of military aviation is devoted to combat related missions, this is something a civilian will never see (at least as far as I know). This includes but is not limited to surveillance, escorts, combat and other military related missions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The military operates troop transport and cargo planes much like commercial operations do and they have pilots who fly them. I would think the tasks are very similar since moving people and cargo is moving people and cargo whether for the military or a civilian organization. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The military obviously had access to flying some planes that would be tough to get into as a civilian (fighter jets mainly). One operation that Civilian pilots will never see is take off and landing on a carrier. That is unique to Navy operations and as far as I know there is no way to do it as a civilian or even train for it (unless you can buy a carrier). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as regulations go the military aircraft and pilots are subject to military regulations (in terms of up keep and things like that) and must adhere to those rules which I believe are different in some cases than the FARs that govern US commercial and Private operations. That being said, if flying in US airspace the same rules apply to military planes that apply to civilian planes. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="62" LastEditDate="2015-06-03T17:04:56.530" LastActivityDate="2015-06-03T17:04:56.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15387" PostTypeId="1" AcceptedAnswerId="15390" CreationDate="2015-06-03T16:19:14.273" Score="16" ViewCount="1648" Body="&lt;p&gt;I was looking at pictures of WWII planes and noticed that the SBD Dauntless had 3 indentations towards the tip of the wing. What were these for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9606E.png&quot; alt=&quot;SBD Dauntless&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="1696" LastEditDate="2015-06-03T17:11:46.737" LastActivityDate="2015-08-27T03:36:28.277" Title="What are these three indentations on the SBD's wing?" Tags="&lt;wing&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15388" PostTypeId="2" ParentId="15387" CreationDate="2015-06-03T16:40:35.723" Score="17" Body="&lt;p&gt;This is a better picture showing those &lt;em&gt;indentations&lt;/em&gt; (or are they?):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pujjI.jpg&quot; alt=&quot;Douglas SBD Dauntless&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://www.aviation-history.com/douglas/sbd.html&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They appear to be wing slots (or &lt;a href=&quot;http://en.wikipedia.org/wiki/Leading_edge_slot&quot; rel=&quot;noreferrer&quot;&gt;leading edge slots&lt;/a&gt;). More details are &lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/501-600/awa537-Dauntless-Bailey/00.shtm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://forum.warthunder.com/index.php?/topic/212068-1451155-sbd-missing-leading-edge-fixed-wing-slots/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-03T16:40:35.723" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15389" PostTypeId="1" AcceptedAnswerId="15522" CreationDate="2015-06-03T16:53:54.260" Score="13" ViewCount="1876" Body="&lt;p&gt;The recent question &lt;a href=&quot;https://aviation.stackexchange.com/q/15335/755&quot;&gt;When a large commercial jet touches down, is it committed to stopping?&lt;/a&gt; referenced the crash of &lt;a href=&quot;http://en.wikipedia.org/wiki/Red_Wings_Airlines_Flight_9268&quot; rel=&quot;nofollow noreferrer&quot;&gt;Red Wings Airlines Flight 9268&lt;/a&gt;, which overran the end of the runway at nearly full touchdown speed due to failure of the reversers to deploy. According to the Wiki article, due to a crosswind, the aircraft touched down on only one of its main gear. Even once the nose gear was on the ground, the right main gear strut had still not compressed. The pilots selected full reverse thrust when the nose gear touched down. Since the right gear strut had not been compressed, the reversers were not deployed, however, the engines still spooled up, resulting in forward thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the reasoning behind not deploying the reversers when one or both of the main gear struts isn't compressed. However, it seems to me that preventing deployment of the thrust reversers should also prevent spooling up the engines for exactly the reasons that the Red Wings flight crashed. Applying full forward thrust when the pilots have selected full reverse thrust seems like a very bad idea to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering whether this behavior is typical of modern transport-category jets. &lt;strong&gt;That is, would, for example, a Boeing or Airbus aircraft prevent the reversers from deploying, but still spool up the engines (as the Tu-204 did in this accident) or would they also prevent engine spool up when reverse thrust is selected while thrust reverser deployment is locked out?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I missing a reason why still spooling up the engines would be desired when reverser deployment is locked out?&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-06-08T00:00:02.180" Title="Do the engines still spool up when reverse thrust is selected, but the reversers are not deployed?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;&lt;thrust-reverser&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15390" PostTypeId="2" ParentId="15387" CreationDate="2015-06-03T16:57:55.033" Score="19" Body="&lt;p&gt;According to &lt;a href=&quot;https://books.google.com/books/about/The_Dauntless_Dive_Bomber_of_World_War_T.html?id=sotfC1gBbsoC&amp;amp;hl=en&quot;&gt;&quot;The Dauntless Dive Bomber of World War Two&quot;&lt;/a&gt; by Barrett Tillman, they are &quot;letter-box&quot; anti-stall leading edge wing slots added to improve the planes stability when approaching the 78knot stall speed during landings (and take offs, actually.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial versions tended to not be able to build up enough speed during the (catapult-less) take offs from the carriers of WW2, and would simply drop off the front edge of a carrier. Adding the three slots basically fixed (or lowered) the speed of stall.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-06-03T18:39:49.333" LastActivityDate="2015-06-03T18:39:49.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15391" PostTypeId="1" CreationDate="2015-06-03T16:59:00.107" Score="16" ViewCount="21845" Body="&lt;p&gt;The FAA does not have an age limit for pilots flying under Part 135 regulations, however ICAO specifies an age limit of 65 (with other restrictions after the age of 60).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NBAA has a nice &lt;a href=&quot;http://www.nbaa.org/admin/personnel/age-60/&quot;&gt;Age 60 Briefing&lt;/a&gt; which discusses this, but at the end they say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most of the States that have authorized their pilots to fly as&#xA;  pilot-in-command in commercial air transport operations after they&#xA;  reach the age specified in 2.1.10.1 also authorize pilots holding a&#xA;  license issued or validated by another States to fly in their own&#xA;  airspace under the same condition.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;However, ICAO does not collect information on States authorizing&#xA;  pilots to fly in their airspace after reaching the age of 60 and&#xA;  cannot provide information on the subject. Pilots seeking such&#xA;  information must contact individual Civil Aviation Authorities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is there any resource available which covers which countries allow pilots to fly over the age of 65?  For instance, I know that Europe does not allow it, but that some others do.  I am particularly curious the countries close to the US, such as Canada, Mexico, the Bahamas, and those in the Caribbean, Central and South America.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-07-04T11:06:51.717" LastActivityDate="2016-07-04T11:06:51.717" Title="Which countries allow pilots to fly over the age of 65 for International Part 135 Operations?" Tags="&lt;faa-regulations&gt;&lt;pilots&gt;&lt;icao-sarps&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15392" PostTypeId="2" ParentId="15375" CreationDate="2015-06-03T18:48:01.460" Score="18" Body="&lt;p&gt;The main advantage is its lower flight Mach number of 0.74. This allows it to use minimum sweep, which in turn reduces wing area, structural masses and thrust requirements. Now pick the right definition for efficiency (one that neglects speed), add the engine fuel consumption expected in 20 years, and the concept looks like a winner. If fuel prices go to \$200 or \$300 a barrel, this type of aircraft will lower the cost of flying substantially. The double-bubble fuselage will contribute only a little to the overall savings, though. Most will come from the (hypothetical!) engines and the high aspect ratio wings with little sweep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the lower flight speed is compensated by the claim of much shorter boarding times, so the double bubble comes out ahead in block times. The only reasoning is that passengers will board more quickly because they can choose between two aisles to get to their seats. &lt;a href=&quot;https://aviation.stackexchange.com/questions/12300/why-dont-airlines-load-their-passengers-like-freight&quot;&gt;Very questionable!&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is page 105 from &lt;a href=&quot;http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this report&lt;/a&gt; which shows the fuel consumption improvement of the separate steps from a Boeing 737 reference design to the D8.1 concept. The biggest contribution is from lowering cruise Mach (and increasing cruise lift coefficient, which allows to reduce wing area) and from engine optimization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/G7OcC.png&quot; alt=&quot;page 105: TSFC evolution&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it looks now, the marginal cost of fracking will keep oil prices below $70 for the next years, and airlines will keep ordering planes which look like those they operate today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking through the proposals in the PDF linked in your comment, most of them make me cringe. Since the Seventies we see the same concepts for supersonic travel, and here they are again, only presented in different colors. Some subsonic designs are sound, but again we see hopeless concepts like the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3428/do-box-wings-suffer-from-induced-drag-the-same-way-as-normal-wings&quot;&gt;boxed wing&lt;/a&gt; which is kept alive by a stream of NASA grants, only because it looks so different. I am equally skeptical of those &lt;a href=&quot;https://aviation.stackexchange.com/questions/12782/why-are-there-no-blended-wing-passenger-airplanes-in-operation&quot;&gt;blended wing&lt;/a&gt; concepts which pop up with every new generation of aircraft designers.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-06-04T13:49:49.137" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15393" PostTypeId="5" CreationDate="2015-06-03T19:06:57.333" Score="0" Body="&lt;p&gt;The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders &quot;radiate&quot; outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is called a &quot;star engine&quot; (German Sternmotor, French moteur en étoile) in some languages. The radial configuration was very commonly used for aircraft engines before turbine engines became predominant.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorDisplayName="user8732" LastEditDate="2015-06-03T20:18:19.043" LastActivityDate="2015-06-03T20:18:19.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15394" PostTypeId="4" CreationDate="2015-06-03T19:06:57.333" Score="0" Body="The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders &quot;radiate&quot; outward from a central crankcase like the spokes of a wheel." OwnerDisplayName="user8732" LastEditorDisplayName="user8732" LastEditDate="2015-06-03T19:41:01.177" LastActivityDate="2015-06-03T19:41:01.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15395" PostTypeId="2" ParentId="15326" CreationDate="2015-06-03T21:14:11.120" Score="3" Body="&lt;p&gt;Briefly, &quot;overhaul&quot; isn't a strictly defined term but it's generally used to refer to the intensive inspection, maintenance and repair of an aircraft component, frequently - but not exclusively - the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The word overhaul by itself is a general term that's used in all sorts of places but it's not defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt;, for example. The most specific definition I could find is in &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/international/bilateral_agreements/baa_basa_listing/media/Maint_Annex_2_Extract.pdf&quot; rel=&quot;nofollow&quot;&gt;this agreement&lt;/a&gt; between the FAA and EASA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Overhaul&quot; means a process that ensures the aeronautical article is&#xA;  in complete conformity  with the applicable service tolerances&#xA;  specified  in the type certificate  holder's, or equipment &#xA;  manufacturer's instructions for  continued airworthiness, or in  the&#xA;  data which is approved or  accepted by the Authority.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may&#xA;  describe an article as being overhauled unless it  has been at least &#xA;  disassembled, cleaned, inspected, repaired as necessary, reassembled&#xA;  and tested in accordance  with the above-specified data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that that definition only mentions &quot;aeronautical articles&quot;, which is very broad indeed and not limited to just engines, airframes or anything else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the general aviation world, a very common usage of &quot;overhaul&quot; is in the context of piston engines, which have a &lt;a href=&quot;http://en.wikipedia.org/wiki/Time_between_overhaul&quot; rel=&quot;nofollow&quot;&gt;Time Between Overhaul&lt;/a&gt; (TBO or TBOH) set by the manufacturer. Once an engine reaches that number of hours, it needs to be overhauled. But even there, the term isn't precise and the FAA has a circular called &lt;em&gt;Reciprocating Engine Overhaul Terminology and Standards&lt;/em&gt; that explains what it usually means:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. Overhaul.  In the general aviation industry, the term engine&#xA;  overhaul has two  identifications that make a  distinction between the&#xA;  degrees of work on an engine:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Major Overhaul.  A major overhaul&#xA;  consists of the complete disassembly of an  engine. The overhaul&#xA;  facility inspects the engine, repairs it as necessary, reassembles,&#xA;  tests, and  approves it for return to service within the  fits and&#xA;  limits specified by the manufacturer’s  overhaul data. This could be&#xA;  to new fits and limits or serviceable limits. The engine owner  should&#xA;  clearly understand what fits and limits should be used when  the&#xA;  engine is presented for  overhaul. The owner should also be aware of&#xA;  any replaced parts, regardless of condition, as a  result of a&#xA;  manufacturer’s overhaul data,  SB, or an Airworthiness Directive (AD).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Top Overhaul.  Top overhaul consists of repair to  parts outside&#xA;  of the crankcase, and  can be accomplished without completely&#xA;  disassembling the entire engine. It can include the  removal of&#xA;  cylinders, inspection and repair to cylinders, inspection and repair&#xA;  to cylinder walls,  pistons, valve-operation mechanisms, valve guides,&#xA;  valve seats, and the replacement of piston  and piston rings. All&#xA;  manufacturers do not recommend a top overhaul. Some manufacturers &#xA;  indicate that a powerplant requiring work to this extent  should&#xA;  receive a complete overhaul.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apart from that usage, the term &lt;a href=&quot;http://en.wikipedia.org/wiki/Maintenance,_repair,_and_operations&quot; rel=&quot;nofollow&quot;&gt;MRO (Maintenance, Repair and Overhaul)&lt;/a&gt; seems to be &lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/&quot; rel=&quot;nofollow&quot;&gt;used&lt;/a&gt; in the airline industry to describe maintenance facilities, but there isn't any specific definition that I could find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there's no single definition of &quot;overhaul&quot;. It just means that you've very thoroughly inspected and tested something on an aircraft, whether it's an engine or a wheel, and you've verified that it's fit to be used in flight, i.e. it's airworthy. The reasons why it's important are probably obvious; they're the same reasons that your car needs regular servicing to run safely, efficiently and reliably.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-06-03T21:14:11.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15396" PostTypeId="1" CreationDate="2015-06-03T21:43:14.450" Score="8" ViewCount="2239" Body="&lt;p&gt;Last week in Ecuador I was on a flight in a small plane (twin engine prop, full with pilot and 5 passengers). The passenger door opened in flight. I was in a position to grab the door and pull it back to the plane and hold it (against a very strong pull) until I could slam it partially shut and then hold it in place until we landed. It didn't seem like that big of a deal except when the door first flew open the plane seemed to drop about 50 feet. What caused the drop in altitude? &lt;/p&gt;&#xA;" OwnerUserId="8748" LastEditorUserId="19" LastEditDate="2016-07-28T11:28:20.350" LastActivityDate="2016-07-28T11:28:20.350" Title="How can opening of a door on small plane cause a drop in altitude?" Tags="&lt;aerodynamics&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15397" PostTypeId="2" ParentId="15396" CreationDate="2015-06-03T22:00:30.867" Score="10" Body="&lt;p&gt;In an unpressurized plane the door opening is less of an issue than in a pressurized plane but there are still some issues it presents. Its common for planes to have multiple latching mechanisms to try to prevent this from happening. In some cases they system is not perfect like &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2010/December/8/AD-issued-on-Diamond-DA40-passenger-door-bracket&quot; rel=&quot;noreferrer&quot;&gt;this AD issued for the DA40&lt;/a&gt; relating to the doors coming off in flight (due to improper closing it appears). Being able to run with out a door or open it in flight is even key for things like para-trooping and skydiving   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/i6pxh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the orientation of the door the biggest issue I would foresee is the door shearing off and damaging part of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Empennage&quot; rel=&quot;noreferrer&quot;&gt;empennage&lt;/a&gt;. This could a have serious if not potentially fatal impact on the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Physically speaking the open door will create drag on the plane which may have been related to the decent you felt. It could also have been an inadvertent reaction by the pilot to the possibly loud noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On somewhat of a side note, most aircraft doors are oriented in such a way that the airflow will more or less push them shut (on small GA planes/non pressurized planes). Thus most doors open forwards like the ones on many pipers &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eixlm.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or vertically up so gravity will close them (note the baggage hatch). I would assume this is intentional but it may just be coincidence as that is also how car doors open. Along the opening lines, it is standard emergency procedure in small airplanes to unlatch the door before a forced landing incase the accident mangles the door locks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth some planes are even flown with the hatch open most the time (pictured on the ground here but flown in the same config)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qeL4M.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.askthepilot.com/questionanswers/exits/&quot; rel=&quot;noreferrer&quot;&gt;Here is a nice article&lt;/a&gt; written by a pilot about why it would be very hard (basically impossible) to do on a pressurized plane. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-03T23:15:17.333" LastActivityDate="2015-06-03T23:15:17.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15400" PostTypeId="1" AcceptedAnswerId="15404" CreationDate="2015-06-04T00:51:52.067" Score="34" ViewCount="13536" Body="&lt;p&gt;I was listening to &lt;a href=&quot;https://www.youtube.com/watch?v=SQTqFj_Iat8&quot;&gt;RealATC for a United Flight UAL1074&lt;/a&gt; which declared an emergency needing to return to Washington Reagan National Airport. During the ATC recording, the flight declares an emergency due to a passenger disruption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC asks for something called the Passenger Disturbance Level. The Copilot replies with a Disturbance Level of 2. As I had never heard this asked for before, I was curious as to what the levels are for and what they each mean?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2018-10-31T23:16:36.517" Title="What is a passenger disturbance level?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15401" PostTypeId="2" ParentId="15382" CreationDate="2015-06-04T02:07:08.370" Score="4" Body="&lt;p&gt;The biggest difference is that most everything in commercial aviation is considered administrative in the military.  The tactical employment of our aircraft, the non-administrative portions of flight, is what separates military sorties from commercial flights.  This emphasis on tactical flying has also led to significantly different cultures between commercial and military aviation.  There isn't a commercial pilot I would stand a chance against in a game of FAR/AIM trivia, but I also doubt they'd fare much better if the tables were turned and the questions were related to carrier operations.  We are two separate organizations with two unique mindsets to flying.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-06-04T02:07:08.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15402" PostTypeId="2" ParentId="15400" CreationDate="2015-06-04T02:38:47.277" Score="6" Body="&lt;p&gt;My guess is that it has something to do with &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/daa4c54debeb6dca86256f3400626ab0/c82981dc0608e98e852566fa005219ff!OpenDocument&amp;amp;ExpandSection=2#_Section2&quot;&gt;FAR 121.580&lt;/a&gt; which states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...No person may assault, threaten, intimidate, or interfere with a crewmember in the performance of the crewmember's duties aboard an aircraft being operated under this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The code may be assigned so that the terminal can send appropriate officials to the gate when the plane arrives. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flightsafety.org/ccs/ccs_may_june97.pdf&quot;&gt;This interesting article&lt;/a&gt; breaks it down into 3 &quot;categories&quot; (page 7 table 3) which may be what the pilot was referencing. Looks like this was written in 1997 and may have become law or influenced common standards since then but thats all I can find that seems to be similar to the situation you present. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-04T02:38:47.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15403" PostTypeId="2" ParentId="15326" CreationDate="2015-06-04T03:38:35.767" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Overhauled.&lt;/strong&gt; &#xA;  Describes an airframe, aircraft engine , propeller, appliance, or component &#xA;  part using methods, techniques, and practices acceptable to the Administrator, which has undergone the following:&lt;br&gt;&#xA;  (1)&#xA;  Has been disassembled, cleaned, inspected, repaired when necessary, and &#xA;  reassembled to the extent possible. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2)&#xA;  Has been tested in accordance with approved standards and technical data, or &#xA;  current standards and technical data acceptable to the Administrator (i.e.,&#xA;   manufacturer’s data), which have been developed and documented by the holder of one of the following: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;TC, &lt;/li&gt;&#xA;  &lt;li&gt;Supplemental Type Certificate (STC),or article approval under § 21.8, or&lt;/li&gt;&#xA;  &lt;li&gt;PMA. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Rebuilt.&lt;/strong&gt; &#xA;  Describes an aircraft, airframe, aircraft engine, propeller, or appliance, using new or used parts that conform to new part tolerances and limits or to approved oversized or undersized dimensions that has undergone the following: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1)&#xA;  Has been disassembled, cleaned, inspected, repaired as necessary, and &#xA;  to the extent possible. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2)&#xA;  Has been tested to the same tolerances and limits as a new item. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-62E.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-62E.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also peruse &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2d71c56dee42c822ea65ad24f050346b&amp;amp;mc=true&amp;amp;tpl=/ecfrbrowse/Title14/14cfr43_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;14CFR43 PART 43—MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION&lt;/a&gt;&#xA;in particular 43.2&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Records of overhaul and rebuilding.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No person may describe in any required maintenance entry or form an aircraft, airframe, aircraft engine, propeller, appliance, or component part as being overhauled unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Using methods, techniques, and practices acceptable to the Administrator, it has been disassembled, cleaned, inspected, repaired as necessary, and reassembled; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) It has been tested in accordance with approved standards and technical data, or in accordance with current standards and technical data acceptable to the Administrator, which have been developed and documented by the holder of the type certificate, supplemental type certificate, or a material, part, process, or appliance approval under part 21 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may describe in any required maintenance entry or form an aircraft, airframe, aircraft engine, propeller, appliance, or component part as being rebuilt unless it has been disassembled, cleaned, inspected, repaired as necessary, reassembled, and tested to the same tolerances and limits as a new item, using either new parts or used parts that either conform to new part tolerances and limits or to approved oversized or undersized dimensions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When dealing with regulations, you may not find an exact, all encompassing definition.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-04T03:43:55.323" LastActivityDate="2015-06-04T03:43:55.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15404" PostTypeId="2" ParentId="15400" CreationDate="2015-06-04T04:39:25.727" Score="39" Body="&lt;p&gt;The FAA has &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC90-103.pdf&quot; rel=&quot;noreferrer&quot;&gt;categorized&lt;/a&gt; disturbances into four levels:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Level 1: Disruptive behavior - suspicious or threatening&lt;br&gt;&#xA;    Level 2: Physically abusive behavior&lt;br&gt;&#xA;    Level 3: Life-threatening behavior&lt;br&gt;&#xA;    Level 4: Attempted or actual breach of the flight deck &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These are also ICAO standard classifications from the restricted Doc 9811, according to &lt;a href=&quot;https://web.archive.org/web/20170329101147/https://www.iata.org/whatwedo/safety/Documents/Guidance-On-Unruly-Passenger-Prevention-And-Management-1st-Edition.pdf&quot; rel=&quot;noreferrer&quot;&gt;IATA&lt;/a&gt;. I'm not sure who came up with them first. That IATA document also provides sample things that might be considered to be each level.&lt;/p&gt;&#xA;" OwnerUserId="923" LastEditorUserId="923" LastEditDate="2018-10-31T23:16:36.517" LastActivityDate="2018-10-31T23:16:36.517" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="15405" PostTypeId="1" CreationDate="2015-06-04T05:42:51.757" Score="4" ViewCount="302" Body="&lt;p&gt;Is there any tool or mechanism to do quantitative analysis of aircraft cabin/cockpit air quality?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-08-02T11:12:54.923" Title="How to measure the Aircraft cabin air quality?" Tags="&lt;cabin-design&gt;&lt;air-quality&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15406" PostTypeId="1" AcceptedAnswerId="15480" CreationDate="2015-06-04T07:50:42.813" Score="4" ViewCount="450" Body="&lt;p&gt;In a college experiment with Small Turbine Engine, we were told about the use of Valves for preventing flashbacks in engines. What are the available valves used for preventing flashbacks and what are the pros and cons of using different kind of flashbacks?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-28T11:28:53.070" LastActivityDate="2020-06-15T16:51:27.613" Title="What kind of valves are used to prevent flashback in turbine engines?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;flashback&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15407" PostTypeId="1" CreationDate="2015-06-04T08:01:16.557" Score="3" ViewCount="11572" Body="&lt;p&gt;Can a Boeing 767-200 physically fly at 510 knots at around 400 metres altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it did manage that speed, how likely would a structure failure be?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if those measurements were achieved, how difficult - relatively - would it be to control?&lt;/p&gt;&#xA;" OwnerUserId="8753" LastEditorUserId="8547" LastEditDate="2015-06-04T08:55:46.033" LastActivityDate="2019-07-06T02:05:44.627" Title="Can a Boeing 767-200 fly at 510 knots at a height of 400 metres?" Tags="&lt;aircraft-performance&gt;&lt;jet-engine&gt;&lt;boeing&gt;&lt;engine&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15408" PostTypeId="1" AcceptedAnswerId="15426" CreationDate="2015-06-04T08:15:34.047" Score="6" ViewCount="652" Body="&lt;p&gt;How is an Airfoil categorized as super critical or not super critical? What are the ways to design a super critical airfoils?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2017-03-14T10:06:11.843" LastActivityDate="2017-09-07T15:20:05.173" Title="Which design method is used for super critical airfoils?" Tags="&lt;airfoil&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15410" PostTypeId="1" AcceptedAnswerId="15416" CreationDate="2015-06-04T09:19:02.223" Score="2" ViewCount="217" Body="&lt;p&gt;What are the list of procedures (checks) followed by A320 and A380? Are these procedures decided by the airlines and (or) the manufacturer, or by the Civil Aviation Regulatory Authority of the respective country?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-04T12:15:05.123" LastActivityDate="2015-06-04T12:32:06.413" Title="Regular procedure followed by the pilots before takeoff?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;takeoff&gt;&lt;pilots&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2015-06-04T13:15:44.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="15411" PostTypeId="2" ParentId="15396" CreationDate="2015-06-04T09:24:56.790" Score="2" Body="&lt;p&gt;There can be many possible explanations to the Drop in altitude, and the most likely is being explained below:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Increase in drag due to opening of the door, would result in decrease in velocity of the plane. This would reduce the lift and hence a loss in altitude would be observed. But, as soon as the altitude would have dropped, the pilot would have observed it and increased the throttle to counter that, and hence stabilizing the plane mid air.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-04T09:24:56.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15412" PostTypeId="2" ParentId="15235" CreationDate="2015-06-04T09:34:11.833" Score="0" Body="&lt;p&gt;I guess there's no current experimental evidence to answer the question about an airplane with an hybrid engine and an added jet engine, but there are some publications about hybrid airplanes, such as: 'A simplified method to calculate the fuel burn of a hybrid electric airplane', R Jagannath et al, in 50th AIAA/ASME/SAE meeting, Propulsion and Energy forum, 2014&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-06-04T09:34:11.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15413" PostTypeId="2" ParentId="15385" CreationDate="2015-06-04T09:51:08.303" Score="1" Body="&lt;p&gt;I am going to work in SI units for all engineering work, anything else would cause instant insanity on my side. I'll leave the altitude in feet (isn't used) and convert speed from knots to m/s so you can follow the flow easily. Since $C_L$ is unitless it should not matter what units you use in the calculation as long as you are consistent.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Altitude: 34000 [ft] (not used)&lt;/li&gt;&#xA;&lt;li&gt;$V$ (true air speed): 442 [knots] = 227 [m/s]&lt;/li&gt;&#xA;&lt;li&gt;S = 112.6 [m&lt;sup&gt;2&lt;/sup&gt;]&lt;/li&gt;&#xA;&lt;li&gt;$\rho_0$ = 1.225 [kg/m&lt;sup&gt;3&lt;/sup&gt;]&lt;/li&gt;&#xA;&lt;li&gt;$\frac{\rho}{\rho_0}$=0.322 [-] (from your table)&lt;/li&gt;&#xA;&lt;li&gt;$\rho$ = $1.225 \cdot 0.322 = 0.394$ [kg/m&lt;sup&gt;3&lt;/sup&gt;]&lt;/li&gt;&#xA;&lt;li&gt;$\frac{1}{2}\rho V^2 S$ = $\frac{1}{2} 0.394\cdot 227^2 \cdot112.6 = 125\cdot10^4 $[N]&lt;/li&gt;&#xA;&lt;li&gt;$m$ = MLM = 64500 [kg]&lt;/li&gt;&#xA;&lt;li&gt;W = $m\cdot g$ = $64500\cdot 9.81$ = $63\cdot10^4$ [N]&lt;/li&gt;&#xA;&lt;li&gt;$C_L$ = $\frac{W}{\frac{1}{2}\rho V^2 S}$=$\frac{63\cdot 10^4}{125\cdot 10^4}$ = 0.5&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I did take full maximum landing mass for this calculation. If you want to apply corrections then note that the $C_L$ value scales linearly with the mass. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One further note:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume your data is derived from ADS-B. ADS-B transmits groundspeed, whilst you should work with true airspeed in these formula's. The difference between them is the tailwind (or headwind) component. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-05T06:55:21.943" LastActivityDate="2015-06-05T06:55:21.943" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15414" PostTypeId="2" ParentId="15405" CreationDate="2015-06-04T09:52:30.017" Score="2" Body="&lt;p&gt;A few years ago, the Australian Civil Aviation Safety Authority convened an  &lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90041&quot; rel=&quot;nofollow&quot;&gt;Expert Panel on Aircraft Air Quality&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From page 138 of the report they discuss the available monitoring devices. From my brief readthrough, there were no real monitoring devices for this purpose at the time (2009) however research was being conducted. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-06-04T09:52:30.017" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15415" PostTypeId="2" ParentId="15389" CreationDate="2015-06-04T11:49:30.633" Score="-1" Body="&lt;p&gt;The behavior sounds exactly right, at least in theory. Once you touch down, there are two viable options: Either you perform a go-around (requires thrust) or you come to halt (which can be done with thrust reversers). Continuing at the same slow speed with the same limited thrust never is a good idea.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-06-04T11:49:30.633" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15416" PostTypeId="2" ParentId="15410" CreationDate="2015-06-04T12:32:06.413" Score="-3" Body="&lt;p&gt;Try to search &quot;Before Takeoff Checklist&quot;. Manufacturer will provide standard checklist but airlines can modify it. &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-06-04T12:32:06.413" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15417" PostTypeId="2" ParentId="15407" CreationDate="2015-06-04T12:36:19.717" Score="6" Body="&lt;p&gt;It would, in all likelihood, be impossible for a large transport category jet to even reach an airspeed of 500 knots at an altitude that low. Drag increases with the square of the airspeed and the transsonic region presents some additional challenges on top of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 767 should have sufficient thrust to accelerate past Vmo at low altitude, but Vmo for a 76- is 360 knots at MSL, a long way away from 500. Even if structural and powerplant failures due to overstress weren't an issue, it's safe to say that a 76- would be drag-limited from reaching anywhere near 500 knots in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to failure modes, there are structural concerns, skin integrity concerns, powerplant concerns, and Mach tuck, and one or more of these would be encountered long before you had a chance to read 500 on the Airspeed Indicator.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Bending of the airframe - going sufficiently fast will induce the various aerodynamic structures on the aircraft the generate forces and turning moments in excess of what the structure was designed to handle, leading to plastic deformation (and possibly outright failure if the stresses are sufficiently large)&lt;/li&gt;&#xA;&lt;li&gt;Control surface flutter - this is probably less of a concern in fly-by-wire and hydraulically-actuated control surfaces than for free control surfaces, but at sufficiently high speeds, air particles will strike the control surfaces with sufficient force to displace them and cause them flutter (ailerons are by far the most susceptible to this and the infamous control column &quot;buzz&quot; is caused by this). Sufficiently aggravated flutter has caused control surface separation in several fatal accidents.  &lt;/li&gt;&#xA;&lt;li&gt;Skin integrity - sufficient suction over the top of the wings has been known to cause material, rivets, and inspection panels to separate and compromise the surface. Probably less of a concern for a stressed aluminium metal or composite skin than for a canvas skin.&lt;/li&gt;&#xA;&lt;li&gt;Mach tuck - the center of pressure moves rearward along the wing chord when the aircraft enters the transsonic regime (the exact speed and characteristics of this shift differ by aircraft) and causes nose-down pitching moments, which may become impossible to overcome. This effect is aggravated in a conventional tailplane arrangement by the generation of standing shockwaves and the subsequent change in airflow separation characteristics.&lt;/li&gt;&#xA;&lt;li&gt;Powerplant failure - reaching 500 knots would require the powerplant to generate tremendous amounts of thrust, requiring a much greater displacement of air through the compressors (and turbines) and a much hotter burn in the combustion chamber. The resulting engine rotational speeds and temperatures would ruin the engine for further use, if not cause it experience an outright structural failure. There's a pretty infamous case of an Egyptian MiG-25 overflying the Sinai Peninsula at Mach 3+ (the Foxbat was rated for a maximum of 2.8); the engines were toast afterwards.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Though not necessarily a failure mode, something to watch out for in fast-travelling swept-wing aircraft with large wingspans is the possibility the aerodynamic forces might twist the wingtips to the point where aileron functionality is reversed from normal.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, the control difficulties at such a high speed would stem more from the fact that the control surfaces (especially ailerons) become much more effective at higher speeds (less displacement is necessary in order to generate the forces necessary). Ordinarily, this might lead to an aircraft that is responsive bordering on twitchy and would require very light control inputs, but the story is a bit more complicated in an aircraft like the 76- due to the role played by the envelope protection software and the hydraulic actuation system. &lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-06-04T14:13:53.030" LastActivityDate="2015-06-04T14:13:53.030" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="15418" PostTypeId="2" ParentId="15389" CreationDate="2015-06-04T12:44:25.077" Score="2" Body="&lt;p&gt;To activate reverse thrust you must move throttles back. This movement is physically prevented by the system that monitors if the airplane is in the air. But if something breaks then it's possible that the engine will provide direct thrust.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="1467" LastEditDate="2015-06-04T13:26:26.140" LastActivityDate="2015-06-04T13:26:26.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15419" PostTypeId="1" AcceptedAnswerId="15423" CreationDate="2015-06-04T13:31:45.363" Score="33" ViewCount="6486" Body="&lt;p&gt;The &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot; rel=&quot;noreferrer&quot;&gt;F-4 Phantom&lt;/a&gt; has an interesting collection of sensors at the extreme rear of the empennage. &lt;strong&gt;What are these sensors for?&lt;/strong&gt; My daughter calls them them smiley sensors but I suspect that is not the proper technical term. Her guesses as to their real purpose:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Detect other airplanes.&lt;/li&gt;&#xA;&lt;li&gt;Detect smiles.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Which one is it?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VuKdW.jpg&quot; alt=&quot;F4 from the rear&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qoajm.jpg&quot; alt=&quot;F4 from the rear angled&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9113" LastEditorUserId="15311" LastEditDate="2017-12-05T20:08:43.203" LastActivityDate="2017-12-05T20:08:43.203" Title="What is the smiley face sensor at the stern of the F-4 Phantom?" Tags="&lt;military&gt;&lt;sensors&gt;&lt;f-4&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15420" PostTypeId="1" CreationDate="2015-06-04T13:39:53.607" Score="4" ViewCount="147" Body="&lt;p&gt;Western miltary a/c maintenance requires routine weighing of the plane yearly or during major inspections.Whereas Russian miltary a/c maintenance does not insist on this kind of weighing,so much so that weighing is not part of any maintenance  schedule after initial manufacture ! Can some one give any plausible reason for this anomaly ?&lt;/p&gt;&#xA;" OwnerUserId="8754" LastEditorUserId="19" LastEditDate="2016-07-28T11:34:03.773" LastActivityDate="2016-07-28T11:34:03.773" Title="Why are aircraft of Russian origin not subject to frequent weighing and CG calculations like western aircraft?" Tags="&lt;military&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15421" PostTypeId="2" ParentId="15407" CreationDate="2015-06-04T14:30:38.957" Score="20" Body="&lt;p&gt;The speed is secondary - what determines the physical limits of the Boeing 767 is Mach number and dynamic pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;510 kts at 400 m in standard atmospheric conditions equals Mach 0.775. This is well within the limits of the Boeing 767. But at 400 m it produces a dynamic pressure of 40,567 N/m², and that is too much. The maximum dive speed $v_D$ of the 767 is 420 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This only means that flying at 510 kts is illegal, but it is still possible. If the airplane dove down to those 400m from enough altitude, it would entirely be capable to reach this speed, but would slow down once it stops diving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several effects which can cause a catastrophic failure when flying too fast:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the aircraft flies into a gust, the resulting load factor can overstress the structure.&lt;/li&gt;&#xA;&lt;li&gt;When the pilot commands large control inputs, he will also overstress the structure.&lt;/li&gt;&#xA;&lt;li&gt;Flutter might also cause structural damage.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The maximum Mach number of the 767 is 0.91 (0.05 above the maximum cruise Mach number, &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_767#Specifications&quot;&gt;which is 0.86&lt;/a&gt;), and this corresponds to 523 kts in 11,000 m.  Thankfully, certification requirements demand a margin of 20% between the maximum speeds and flutter onset speeds, so flutter might be close, but is still tens of miles per hour away when diving to 510 kts. Remember, to experience flutter you need also to excite the motion first. &lt;a href=&quot;https://www.metabunk.org/debunked-the-role-of-aeroelastic-flutter-in-the-events-of-9-11.t3359/&quot;&gt;Here&lt;/a&gt; is a good discussion of this topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, flying a Boeing 767 in 400 m at 510 kts is not recommended, but is entirely possible and most likely even safe when done in calm air and by a calm pilot. It only won't last long, because the engines will not produce enough thrust to maintain that speed. Flying this dive requires guts, but no special skills.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-04T14:38:17.580" LastActivityDate="2015-06-04T14:38:17.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15422" PostTypeId="2" ParentId="15420" CreationDate="2015-06-04T14:48:20.903" Score="5" Body="&lt;p&gt;Western doctrine is to keep all aircraft of one type in identical conditions. Once you change one thing, you do it for all aircraft of this type at the same time (or create a subtype). Routine weighing makes sure that the individual aircraft conforms to the type certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Russian doctrine sees every airplane as an individual, and if something is changed, it needs to be documented, but not necessarily done on all other planes of that type. To every airplane belongs a (mostly) metal box with all documents, and they should tell you exactly what has been modified since it was produced. Weighing is now part of maintenance, but needs not be done if nothing has been modified.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-06-04T14:48:20.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15423" PostTypeId="2" ParentId="15419" CreationDate="2015-06-04T14:58:49.143" Score="28" Body="&lt;p&gt;Your daughter is right as &lt;a href=&quot;http://www.b-domke.de/AviationImages/Phantom/7019.html&quot; rel=&quot;noreferrer&quot;&gt;explained here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 'bug-eyed' face of the parabrake door mounting the two&#xA;  rear-hemisphere radar warning antennas.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So they do detect other airplanes and probably the smiles of their pilots too as they are getting close to the phantom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lm1Bn.jpg&quot; alt=&quot;Rear Antennas&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-04T14:58:49.143" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15424" PostTypeId="5" CreationDate="2015-06-04T15:08:32.010" Score="0" Body="&lt;p&gt;Spanning the continents of Europe and Asia, Russia is the largest country in the world, containing nearly 1/8th of the world's inhabited land area.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1696" LastEditDate="2015-06-04T15:44:26.887" LastActivityDate="2015-06-04T15:44:26.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15425" PostTypeId="4" CreationDate="2015-06-04T15:08:32.010" Score="0" Body="For questions specifically related to Russia, the largest country in the world, situated in Europe and Asia." OwnerDisplayName="user8732" LastEditorUserId="3674" LastEditDate="2016-02-26T01:40:28.260" LastActivityDate="2016-02-26T01:40:28.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15426" PostTypeId="2" ParentId="15408" CreationDate="2015-06-04T15:09:10.873" Score="7" Body="&lt;p&gt;Critical speed or Mach number is the speed at which the speed of sound is locally reached somewhere along the flow around an airfoil. A supercritical airfoil can tolerate operating speeds slightly above the critical speed (hence the name), which means that a pocket of supersonic flow will show up, most likely on the upper surface. What qualifies an airfoil as supercritical is that the recompression does not need a &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing&quot;&gt;shock&lt;/a&gt;, but can be done shock-free for a small lift coefficient range by clever shaping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/13453/what-is-the-actual-air-speed-over-and-under-a-wing-due-to-bernoullis-principle/13501#13501&quot;&gt;this question&lt;/a&gt; for more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Calculation of a supercritical airfoil is best done with a computer program which models the flow conditions around Mach 1 faithfully. Once such program would be &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/tsfoil2.f&quot; rel=&quot;nofollow noreferrer&quot;&gt;TSFOIL&lt;/a&gt;. The picture below shows one result for the BACJ airfoil at Mach 0.8, and you can see that the speed on the upper surface reaches Mach 1.3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xev7k.png&quot; alt=&quot;B747 Mach distribution&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-06-04T15:09:10.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15427" PostTypeId="5" CreationDate="2015-06-04T15:13:56.967" Score="0" Body="&lt;p&gt;The intensity of heat found in an object or living thing. The three most popular scales to measure temperature units are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Centigrade/Celsius&lt;/li&gt;&#xA;&lt;li&gt;Fahrenheit&lt;/li&gt;&#xA;&lt;li&gt;Kelvin&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="8282" LastEditDate="2018-10-22T21:11:16.620" LastActivityDate="2018-10-22T21:11:16.620" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15428" PostTypeId="4" CreationDate="2015-06-04T15:13:56.967" Score="0" Body="The intensity of heat found in an object or living thing." OwnerDisplayName="user8732" LastEditorUserId="1467" LastEditDate="2015-06-04T15:31:31.697" LastActivityDate="2015-06-04T15:31:31.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15429" PostTypeId="5" CreationDate="2015-06-04T15:22:40.300" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-04T15:22:40.300" LastActivityDate="2015-06-04T15:22:40.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15430" PostTypeId="4" CreationDate="2015-06-04T15:22:40.300" Score="0" Body="ICAO defines an incident as an occurrence, other than an accident, associated with the operation of an aircraft which affects or could affect the safety of operation." OwnerDisplayName="user8732" LastEditorUserId="1696" LastEditDate="2015-06-04T15:45:29.350" LastActivityDate="2015-06-04T15:45:29.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15431" PostTypeId="5" CreationDate="2015-06-04T16:45:17.053" Score="0" Body="&lt;p&gt;Cold weather is weather that is officially defined as less than or equal to 0 degrees centigrade (32 Fahrenheit).&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1467" LastEditDate="2015-06-05T03:54:34.890" LastActivityDate="2015-06-05T03:54:34.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15432" PostTypeId="4" CreationDate="2015-06-04T16:45:17.053" Score="0" Body="Cold weather is weather that is officially defined as less than or equal to 0 degrees centigrade (32 Fahrenheit) " OwnerDisplayName="user8732" LastEditorDisplayName="user8732" LastEditDate="2015-06-04T16:57:38.407" LastActivityDate="2015-06-04T16:57:38.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15433" PostTypeId="2" ParentId="9706" CreationDate="2015-06-04T17:41:39.570" Score="2" Body="&lt;p&gt;Some more information about this particular item.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/43dfb85075f8bead86256ced00732339/$FILE/022106.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AD 2002-21-06&lt;/a&gt;&lt;/strong&gt; addresses the issues with detecting wing ice on the DC-9 series of aircraft (which includes the MD-83).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft of this type have a wing surface ice detection system installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0ydc7.png&quot; alt=&quot;Wing Ice Detection system diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a modification available that automatically moves fuel between the wing and center fuel tanks to prevent the supercooled fuel from accumulating in wing tanks.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-06-04T18:25:48.873" LastActivityDate="2015-06-04T18:25:48.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15434" PostTypeId="2" ParentId="15295" CreationDate="2015-06-04T18:17:40.053" Score="2" Body="&lt;p&gt;There isn't a limit (in the USAF at least).  I seem to remember hearing a story of a SQ/CC at Luke that had ejected twice.  I will do my best to find a reg/pub that talks about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, not all ejections cause injuries.  I've also known pilots that ejected and were completely fine.  A controlled ejection at 200-300 knots is a lot different than an uncontrolled ejection at 500+.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-04T18:17:40.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15435" PostTypeId="5" CreationDate="2015-06-04T18:25:53.570" Score="0" Body="" OwnerUserId="8547" LastEditorUserId="14897" LastEditDate="2018-06-17T06:05:22.410" LastActivityDate="2018-06-17T06:05:22.410" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15436" PostTypeId="4" CreationDate="2015-06-04T18:25:53.570" Score="0" Body="Questions about controlled changes to the flight path or a series thereof." OwnerUserId="8547" LastEditorUserId="14897" LastEditDate="2018-06-17T06:05:22.410" LastActivityDate="2018-06-17T06:05:22.410" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15437" PostTypeId="1" AcceptedAnswerId="15438" CreationDate="2015-06-04T18:45:24.510" Score="13" ViewCount="1838" Body="&lt;p&gt;I have been looking over some pictures of military airplanes, and I noticed that some of the more modern air planes have flaps on the exhaust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/c6eYg.jpg&quot; alt=&quot;These are the flaps on the exhaust&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering if anyone knew what the purpose of the flaps were, and why they are only on modern airplanes&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="3386" LastEditDate="2019-12-31T03:01:54.933" LastActivityDate="2019-12-31T03:01:54.933" Title="What are the flaps on the exhaust of military airplanes for?" Tags="&lt;military&gt;&lt;feature-identification&gt;&lt;flaps&gt;&lt;f-22&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15438" PostTypeId="2" ParentId="15437" CreationDate="2015-06-04T19:06:09.943" Score="7" Body="&lt;p&gt;Those &lt;em&gt;flaps on exhaust&lt;/em&gt; are for &lt;a href=&quot;http://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;noreferrer&quot;&gt;thrust vectoring&lt;/a&gt;. A simple definition would be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the ability of an aircraft [...] to manipulate the direction of the&#xA;  thrust [...] to control the attitude [...] of the vehicle&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;F-22 uses it like &lt;a href=&quot;http://science.howstuffworks.com/f-22-raptor5.htm&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Its] nozzle [...] is the first vectoring nozzle. That means&#xA;  the pilot can move, or vector, the nozzle up and down by 20 degrees.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The gases coming out of the vector nozzle help push the airplane's&#xA;  nose up or down. This vectoring increases the roll rate of the plane&#xA;  by 50 percent, making it much more maneuverable than other fighters.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Thrust vectoring [...] works automatically in response to commands&#xA;  from the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-04T19:06:09.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15441" PostTypeId="2" ParentId="15437" CreationDate="2015-06-04T21:16:57.273" Score="5" Body="&lt;p&gt;Adding to &lt;a href=&quot;https://aviation.stackexchange.com/a/15438/8166&quot;&gt;the above answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These mechanical devises are for thrust vectoring.  Their &lt;em&gt;purpose&lt;/em&gt; is for super-maneuverability, meaning that the aircraft can maintain pitch and yaw control at extreme angles of attack where other non super-maneuverable aircraft would stall, spin, completely loose control, etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This ultimately allows a wider flight envelope and the ability to &quot;push the envelope&quot; further than would be without thrust vectoring.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust vectoring allows a plane to turn harder and faster because, rather than the control surfaces doing most of the work to turn the airframe, the engine exhaust becomes a large component in the vector change, thus reducing the load on the wings and the rest of the airframe.  Loading the wings with high g turns is dangerous beyond the flight envelope - the vectoring eases the load and thus widens the envelope.  Also, point the nozzles in opposing horizontal directions aids in rolling the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning your picture - the F-22 has '2D' thrust vectoring - allowing the exhaust to de deflected up and down over the horizontal axis and controlling &lt;em&gt;2 dimensions&lt;/em&gt; of flight dynamics (pitch and roll).  Aircraft such as the MiG-29OVT (below) have '3D' thrust vectoring, allowing control of &lt;em&gt;3 dimensions&lt;/em&gt; of flight dynamics (pitch, roll, and yaw).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nmcXO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard the MiG's nozzles are sometimes referred to as 'flowers of steel' because of the way they open, close, and move, sometimes completely independently of each other.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The video below shows the beautiful 3D nozzles in action starting at 1:40 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/y6RYQZzLWOk&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;3D Thrust Vectoring&quot;&gt;Video: 3D Thrust Vectoring&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8166" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-04T21:51:49.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15442" PostTypeId="1" AcceptedAnswerId="15451" CreationDate="2015-06-04T21:26:24.363" Score="13" ViewCount="3935" Body="&lt;p&gt;I've seen some reports that say ice forms on the back half of the wing and on the outside edge of the wing (the part furthest from the body) before it will form anywhere else.  I'm wondering if this is true?  Where does ice first form on a wing (in flight) in icing conditions?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="487" LastEditDate="2015-06-05T09:01:36.033" LastActivityDate="2015-06-05T09:01:36.033" Title="Where does ice collect first on a wing in flight and why?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;icing&gt;&lt;cold-weather&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15443" PostTypeId="5" CreationDate="2015-06-04T21:34:23.450" Score="0" Body="&lt;p&gt;Supplying (a vehicle) with more fuel. There are many different types of refueling. In the military you can refuel on the ground, or in the air (aerial refueling). Their are certain planes capable of refueling in the air such as the &lt;a href=&quot;http://en.wikipedia.org/wiki/Panavia_Tornado&quot; rel=&quot;nofollow&quot;&gt;Tornado GR4&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="1467" LastEditDate="2015-06-05T22:05:38.927" LastActivityDate="2015-06-05T22:05:38.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15444" PostTypeId="4" CreationDate="2015-06-04T21:34:23.450" Score="0" Body="The process of supplying an aircraft with more fuel." OwnerDisplayName="user8732" LastEditorUserId="22726" LastEditorDisplayName="user8732" LastEditDate="2019-06-02T03:09:00.050" LastActivityDate="2019-06-02T03:09:00.050" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15446" PostTypeId="1" CreationDate="2015-06-04T22:17:40.713" Score="3" ViewCount="227" Body="&lt;p&gt;I was watching a plane documentary, and when the part about aircraft carriers came on, I noticed that as soon as the plane hits the aircraft carrier runways, the plane speeds up. &lt;strong&gt;&lt;em&gt;Why&lt;/em&gt;&lt;/strong&gt; is this happening?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question has &lt;em&gt;not&lt;/em&gt; been answered in &lt;a href=&quot;https://aviation.stackexchange.com/questions/475/what-is-the-procedure-for-landing-on-an-aircraft-carrier&quot;&gt;What is the procedure for landing on an aircraft carrier&lt;/a&gt;. This question explains the procedure to throttle up to full military power just after touchdown, however does not address the &lt;strong&gt;&lt;em&gt;reason&lt;/em&gt;&lt;/strong&gt; for doing so.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="3386" LastEditDate="2015-06-05T13:33:43.290" LastActivityDate="2015-06-05T13:33:43.290" Title="Why do planes accelerate when they touch down on a aircraft carrier" Tags="&lt;landing&gt;&lt;aircraft-carrier&gt;&lt;groundspeed&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2015-06-04T22:39:31.633" ContentLicense="CC BY-SA 3.0" />
  <row Id="15448" PostTypeId="1" AcceptedAnswerId="15470" CreationDate="2015-06-05T01:05:50.627" Score="9" ViewCount="7975" Body="&lt;p&gt;So here.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;All&lt;/em&gt; airports &lt;strong&gt;are&lt;/strong&gt; aerodromes. &lt;em&gt;All&lt;/em&gt; aerodromes &lt;strong&gt;are not&lt;/strong&gt; airports.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.differencebetween.info/difference-between-airport-and-aerodrome&quot; rel=&quot;nofollow noreferrer&quot;&gt;Difference between Airport and Aerodrome&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;An aerodrome or airdrome is any place from where flight operations can take place. This can include an airstrip in the middle of nowhere to a commercial airport in the biggest city in the world. An airport is a special type of aerodrome that has satisfied certain certification criteria or regulatory requirements of the ICAO that a regular aerodrome may not have achieved.&lt;/p&gt;&#xA;&lt;p&gt;The term airport implies a certain stature of having satisfied certain certification criteria or regulatory requirements of the ICAO that a regular aerodrome may not have achieved. Hence it can be said that all airports are aerodromes, but not all aerodromes are airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So then what facilities and services does an aerodrome need to have, in order to be certified as an airport in Canada?&lt;/p&gt;&#xA;" OwnerUserId="7670" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-06T12:55:04.167" Title="What is needed to certify an aerodrome as an airport in Canada?" Tags="&lt;terminology&gt;&lt;transport-canada&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15449" PostTypeId="5" CreationDate="2015-06-05T01:08:56.220" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-05T01:08:56.220" LastActivityDate="2015-06-05T01:08:56.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15450" PostTypeId="4" CreationDate="2015-06-05T01:08:56.220" Score="0" Body="An aerodrome is a basic aviation facility, to facilitate landing and takeoffs. Airports are aerodromes, but aerodromes might not be an airport." OwnerUserId="7670" LastEditorUserId="7670" LastEditDate="2015-06-05T02:46:36.903" LastActivityDate="2015-06-05T02:46:36.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15451" PostTypeId="2" ParentId="15442" CreationDate="2015-06-05T01:59:01.667" Score="11" Body="&lt;p&gt;&quot;&lt;a href=&quot;http://en.wikipedia.org/wiki/Icing_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Icing conditions&lt;/a&gt;&quot; is a pretty vague term that encompasses a lot of various situations that can cause &lt;a href=&quot;http://flighttraining.aopa.org/pdfs/SA11_Aircraft_Icing.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;airframe icing (AOPA pdf report&lt;/a&gt;, so it's hard to have one definitive answer. That said, you can expect to accumulate &lt;em&gt;some&lt;/em&gt; degree of ice when flying through moisture (clouds, rain, etc) when outside air temperatures (OAT) are near or below 36°F / 2°C. Also as a rule, an aircraft's tail will likely accumulate ice faster than the wing in &lt;em&gt;all&lt;/em&gt; conditions.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flying through very cold temperatures (-15°C -&gt; -40°C)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When flying in clouds and rain at the very low end of the icing spectrum, the most likely form of accumulation is &lt;a href=&quot;http://www.skybrary.aero/index.php/Rime_ice&quot; rel=&quot;nofollow noreferrer&quot;&gt;rime icing&lt;/a&gt;. This primarily forms on the leading edges of wings and tail surfaces, starting (in most cases) with the tail, and looks (initially, at least) a lot like frost. It can create pretty bizarre structures and is pretty easy to spot. Rime ice is (as far as I have seen or read) not going to accumulate anywhere but on &lt;strong&gt;leading edges&lt;/strong&gt; (wings, nose, engine nacelles, tail) as those are the only parts of the structure impacting the relative wind. Either way, it is highly detrimental to your wing's aerodynamic health.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rime ice can sometimes form 'horns' that start to grow in a V shape forward off the wing, but only in what I imagine are considered severe conditions. The FAA states that rime &quot;typically occurs with temperatures between -15° C. and -20 ° C&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RIHmlm.png&quot; alt=&quot;Rime ice accumulating over pneumatic boots&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flying in relatively warm temperatures (2°C -&gt; -15°C)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At warmer temps, the most likely form is &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=152&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;clear ice&lt;/a&gt;, which is basically like having solid water ice form around the leading edges - again, wings, tail surfaces, nose, engines. It pretty much follows the shape of the leading edge of surface it freezes onto, but it's heavy and still messes with your aerodynamics. Again, like rime, it's freezing more or less on impact (but with larger droplets) wherever the relative wind strikes the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some unusual conditions, aircraft can encounter precip known as &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=155&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;Supercooled Large Droplets&lt;/a&gt; (SLD); these are cold enough to freeze but not on impact, causing a form of icing known as &lt;a href=&quot;http://www.tc.faa.gov/its/worldpac/techrpt/ar0716.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;runback ice (FAA pdf)&lt;/a&gt;. In FAA tests, &quot;ice shape simulations were found to cause substantial penalties to the aerodynamic performance&quot; of multiple NACA airfoils. Runback ice can accumulate pretty far back along a wing, making it difficult or impossible to dislodge using heat or boots (supposedly TKS fluid protection can mitigate this). It's scary stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA states that &quot;Clear ice typically forms when temperatures are around 2° C to -10°C [but] more hazardous clear ice shapes [...] tend to form at temperatures closer to 0°C&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1kBPc.jpg&quot; alt=&quot;Clear ice accumulated on a wing&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flying in medium temperatures (-10°C -&gt; -15°C)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When flying in the middle of the temperature range, aircraft wind up accumulating &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=152&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;mixed ice&lt;/a&gt;, a combination of rime and clear. According to the FAA, &quot;Mixed ice is most likely to form at temperatures between -10° C to -15° C&quot;. It is basically as terrible for aerodynamics as rime ice, and pretty much just as heavy as clear ice. No fun.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Resources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Icing_conditions&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://flighttraining.aopa.org/pdfs/SA11_Aircraft_Icing.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA Safety Advisor&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=152&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Safety course on icing types&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=155&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Safety course on SLD&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-06-05T02:12:04.190" LastActivityDate="2015-06-05T02:12:04.190" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15452" PostTypeId="1" AcceptedAnswerId="15467" CreationDate="2015-06-05T06:57:39.280" Score="4" ViewCount="5742" Body="&lt;p&gt;Airbus is planning to roll out an &lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow&quot;&gt;Airbus A320neo&lt;/a&gt; to replace its current A320 model, and they will offer this option on other models too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does adding more options for engines for potential customers act as an advantage for the Aircraft Manufacturer? Why wouldn't the manufacturer optimize its plane for one engine specifically, to give best performance and roll out the plane like that?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="62" LastEditDate="2015-06-05T14:56:05.063" LastActivityDate="2015-06-05T15:10:14.100" Title="What are the advantages of the Airbus New Engine Option (NEO) program?" Tags="&lt;airbus&gt;&lt;airbus-neo&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15453" PostTypeId="2" ParentId="14842" CreationDate="2015-06-05T07:26:08.107" Score="3" Body="&lt;p&gt;Yes small planes have electric gyros as well. It can be as sophisticated as Garmin 1000 in Cessna 172 or Russian made electric artificial horizon gyro powered by accumulator in a glider Blanik L13. I heard battery didn't last very long though:) Also all turn rate indicators have gyros and the ones I saw were electric powered. This ensures that you can still survive if a vacuum pump fails. Turn indicators used in the eastern block made gliders are powered by simple 4.5V battery.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8466" LastEditDate="2015-06-05T07:31:21.087" LastActivityDate="2015-06-05T07:31:21.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15454" PostTypeId="1" AcceptedAnswerId="15456" CreationDate="2015-06-05T08:16:07.127" Score="7" ViewCount="1920" Body="&lt;p&gt;I have been reading documents about the concepts of Free-Flight and Free-Route that are being implemented (or being simulated to be implemented in the future) in Europe since 2012 by the initiative Single European Sky, that aims to provide a safer and more efficient airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have noticed that the concept is similar but it is treated differently, and I am wondering what's the main difference between these two concepts. Also, is it a safe concept? (It involves more possible conflicts in the airspace, if not carefully implemented).&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="8407" LastEditDate="2015-06-05T08:39:33.247" LastActivityDate="2015-06-05T09:48:58.757" Title="What's the difference between Free-Flight and Free-Route?" Tags="&lt;airline-operations&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15455" PostTypeId="2" ParentId="9975" CreationDate="2015-06-05T09:01:04.270" Score="1" Body="&lt;p&gt;I was in aviation many years in 3 countries in Traffic/Dispatch/Load Control (weight&amp;amp;Balance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As most say on here the smaller aeroplanes are more balance critical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used to take great pride in getting an aeroplane closed up and ready for push back on schedule. I also used to take great pride in getting late pax on board and still getting a schedule. The loadsheet has a box at the bottom labelled LMC. Last Minute Changes.  There is a specific weight allowed, dependent on aircraft, acceptable without having to recalculate. But a competent loadsheet officer should be able to within a very short period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying is not the pleasure it used to be, security has made it far more complex.  I was denied boarding recently in Sofia, check in was just closing as I arrived and the last pax just going through security. The EasyJet aeroplane had not even taxied on to stand and it had a thirty minute turnround. I had no baggage.  Imagine how angry I was, knowing the system, knowing that checking me in would make no difference to the departure. To have a check-in agent telling me the Captain had already completed pre-departure procedures and would not allow a late pax. It was absolute bull, despite how cross I was I knew it was pointless getting angry at check in but internally I was seething.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next flight to MAN wasn't until the following day so it was either  a hotel or flight to London and then train to MAN.  Of course these cheap airlines do not give refunds or transfer so it was a new ticket at great expense.&#xA;There-in lies the crux in my opinion.  I would suggest that the executives at the head of companies such as EasyJet have the policy as a way to increase revenue.  At small airports such as Sofia it takes hardly any time to pass through, security &amp;amp; immigration. Obviously the bigger the airport the more time it takes.  Gone are the days when a breathless Pax Agent would arrive at the gate 10 minutes before push back saying, please can you get these late pax on?&lt;/p&gt;&#xA;" OwnerUserId="8767" LastActivityDate="2015-06-05T09:01:04.270" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15456" PostTypeId="2" ParentId="15454" CreationDate="2015-06-05T09:07:54.897" Score="5" Body="&lt;p&gt;The difference is between the definition itself.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Free Flight : Free flight is a developing air traffic control method that uses no centralized control (e.g. air traffic controllers). Instead, parts of airspace are reserved dynamically and automatically in a distributed way using computer communication to ensure the required separation between aircraft. This new system may be implemented into the U.S. air traffic control system in the next decade.[citation needed] Its potential impact on the operations of the national airspace system is disputed, however.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This effectively means that, if a part of space is reserved for free flight, you can effectively do anything with your flight plan. Moreover this reserved space would change dynamically, so if there is an approaching aircraft nearby., your free flight space changes to accommodate free flight space for the other flight as well. Both of the planes would have &lt;strong&gt;DIFFERENT&lt;/strong&gt; free flight space, and they can adjust their flight plan just in their own flight space. This eliminates the need for ATC completely.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Free Route Airspace : Free Route Airspace (FRA) is a specified airspace within which users may freely plan a route between a defined entry point and a defined exit point. Subject to airspace availability, the route can be planned directly from one to the other or via intermediate (published or unpublished) way points, without reference to the ATS route network. Within this airspace, flights remain subject to air traffic control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here, the Airspace allotment remains under the control of the ATC, which allocates single space to multiple planes, and there one can decide which path to take. Here, inherently there is a possibility of overlapping routes (Because of the same airspace being allotted to multiple planes), and thats why, some routes are allowed in this space, and some are not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uTSHu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-05T09:07:54.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15458" PostTypeId="2" ParentId="15454" CreationDate="2015-06-05T09:48:58.757" Score="2" Body="&lt;p&gt;Moreover, there is the &lt;a href=&quot;http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5347535&quot; rel=&quot;nofollow&quot;&gt;Sectorless ATM Concept&lt;/a&gt; of DLR researchers Korn et al.:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Feasibility of a new air traffic management concept is examined which might increase the efficiency of en-route operations by up to 100%. The concept follows the idea of a sector-less airspace organization. Aircraft entering the airspace (e.g. the German airspace or the entire European Airspace) will be assigned to one controller who is in charge of controlling the aircraft from entry point (or TMA exit point) to exit point of the airspace (or TMA entry point). First simple real time simulations revealed very promising results. The concept seems to enable an easy transition into a user preferred trajectory (direct-to) operations whilst at the same time increasing ATCO’s efficiency and airspace capacity.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They found that in their scenario the number of potential conflicts between  trajectories that take the direct path from entry to exit point decreased about 30° relative to potential conflicts between trajectories on the traditional airways.&lt;/p&gt;&#xA;" OwnerUserId="3859" LastActivityDate="2015-06-05T09:48:58.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15459" PostTypeId="2" ParentId="446" CreationDate="2015-06-05T09:59:17.023" Score="2" Body="&lt;p&gt;Additionally to the answer of user241, countries have different &lt;a href=&quot;https://www.eurocontrol.int/articles/establishing-route-charges&quot; rel=&quot;nofollow&quot;&gt;route charges&lt;/a&gt; that may influence the airlines in their cost trade-off to take different routes. Route charges may be negotiated between airlines and countries, leading to different routes by different airlines.&lt;/p&gt;&#xA;" OwnerUserId="3859" LastActivityDate="2015-06-05T09:59:17.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15460" PostTypeId="1" AcceptedAnswerId="15466" CreationDate="2015-06-05T12:46:24.570" Score="22" ViewCount="7663" Body="&lt;p&gt;I see these jet bridges (or aerobridges) at nearly every new airport I go to. How are aircraft aligned with these bridges, particularly the A380 which has doors on both decks?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="13197" LastEditDate="2018-07-09T22:35:09.670" LastActivityDate="2020-11-18T16:30:36.307" Title="How is an aircraft aligned at a jet bridge?" Tags="&lt;airliner&gt;&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="15461" PostTypeId="2" ParentId="15460" CreationDate="2015-06-05T12:51:57.663" Score="22" Body="&lt;p&gt;The Aircraft aligns with the gate through ground markings, radar sensors and eventually ground operators signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the aircraft stops the jet bridge is aligned with the aircraft's door by an operator that commands the various bridge actuators (wheels, extension, rotation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xz7Zw.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;http://www.igus.eu/wpck/8283/passengerboardingbridges&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-06-05T12:51:57.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15462" PostTypeId="1" AcceptedAnswerId="15476" CreationDate="2015-06-05T13:19:12.223" Score="12" ViewCount="2476" Body="&lt;p&gt;Years ago, I had the opportunity to board a &lt;a href=&quot;http://en.wikipedia.org/wiki/Bell_407&quot;&gt;Bell 407&lt;/a&gt; for a long distance flight and put every question related to helicopters that crossed my mind to the pilot when we were forced to land due to visibility issue and also while we refueled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize now that I've missed something important: do rotorcraft including helicopters have autopilots like fixed wing aircraft do, or is that ruled out due to their peculiar flight mechanics?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="247" LastEditDate="2015-06-17T09:36:24.280" LastActivityDate="2015-06-17T09:36:24.280" Title="Do rotorcrafts like helicopters have autopilots?" Tags="&lt;helicopter&gt;&lt;autopilot&gt;&lt;rotorcraft&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15463" PostTypeId="2" ParentId="15460" CreationDate="2015-06-05T13:24:57.690" Score="22" Body="&lt;p&gt;The bridge can move to an extent but the aircraft is driven up to a designated spot that is marked on the ground. &lt;a href=&quot;https://www.youtube.com/watch?v=ekxL8Z_f2zU&quot; rel=&quot;noreferrer&quot;&gt;Here is a video&lt;/a&gt; of it all happening. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cHBKV.jpg&quot; alt=&quot;Markings on ground&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be also accomplished with someone on the ground directing &#xA;&lt;img src=&quot;https://i.stack.imgur.com/OkmsQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="65" LastEditDate="2015-06-05T14:00:06.463" LastActivityDate="2015-06-05T14:00:06.463" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15464" PostTypeId="2" ParentId="15460" CreationDate="2015-06-05T13:33:34.230" Score="18" Body="&lt;p&gt;They align themselves with the &lt;a href=&quot;http://en.wikipedia.org/wiki/Stand_guidance_system&quot; rel=&quot;noreferrer&quot;&gt;stand guidance system&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Azimuth Guidance for Nose-In Stand (AGNIS) is a passive system which uses a system similar to PAPI lights to display red and green lights to indicate whether the plane is too far left or right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An active system is for example the Honeywell Advanced Visual Docking Guidance. A camera detect the airplane and changes the sign to guide the pilot to the correct place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/d8AYn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;(image source wikipedia)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the plane is aligned to the gate the jet bridge is maneuvered up to the plane's door.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-06-05T21:07:14.317" LastActivityDate="2015-06-05T21:07:14.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15465" PostTypeId="2" ParentId="15448" CreationDate="2015-06-05T13:53:20.950" Score="2" Body="&lt;p&gt;&lt;em&gt;Original Answer&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Aerodrome&lt;/strong&gt;&lt;br /&gt;&#xA;It is an area where:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;aircraft land&lt;/li&gt;&#xA;&lt;li&gt;aircraft take off&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Runway may not be present (in case of a water aerodrome).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Airport&lt;/strong&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;br /&gt;&#xA;By definition&lt;sup&gt;2&lt;/sup&gt;, an airport is an aerodrome with facilities for commercial aviation flights to take off and land&#xA;It is an aerodrome which has:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;facilities to store and maintain aircraft&lt;/li&gt;&#xA;&lt;li&gt;at least one designated operational landing/takeoff area (runway or helipad)&lt;/li&gt;&#xA;&lt;li&gt;hangars&lt;/li&gt;&#xA;&lt;li&gt;terminals&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Fixed-base_operator&quot; rel=&quot;nofollow noreferrer&quot;&gt;fixed base operators&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airport_apron&quot; rel=&quot;nofollow noreferrer&quot;&gt;airport aprons&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;air traffic control centers&lt;/li&gt;&#xA;&lt;li&gt;passenger facilities (restaurants and &lt;a href=&quot;http://en.wikipedia.org/wiki/Airport_lounge&quot; rel=&quot;nofollow noreferrer&quot;&gt;lounges&lt;/a&gt; etc.)&lt;/li&gt;&#xA;&lt;li&gt;emergency services&lt;/li&gt;&#xA;&lt;li&gt;customs&lt;sup&gt;3&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;immigration&lt;sup&gt;3&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h1&gt;Edit&lt;/h1&gt;&#xA;&lt;p&gt;I noticed that the question is updated to be only for Canada. In that case, airport &lt;a href=&quot;https://www.tc.gc.ca/eng/programs/airports-index.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;requires the following&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;have a &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/standards/sms-menu-618.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;safety management system&lt;/a&gt; in place&lt;/li&gt;&#xA;&lt;li&gt;comply with airport &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp312-menu-4765.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;safety standards&lt;/a&gt; and security requirements&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Further reading&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aerodrome&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerodrome&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/airports/engineering/design_standards/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport Design and Engineering Standards (by FAA)&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;http://www.icao.int/safety/Implementation/Library/Manual%20Aerodrome%20Stds.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerodrome Standards (PDF by ICAO)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: Not &lt;em&gt;all&lt;/em&gt; airports must have all of these to qualify as an airport.&lt;br /&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;: I could not find specific regulations which define an airport.&lt;br /&gt;&#xA;&lt;sup&gt;3&lt;/sup&gt;: In case of an international airport&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-05T15:57:49.223" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15466" PostTypeId="2" ParentId="15460" CreationDate="2015-06-05T14:08:16.490" Score="35" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How are aircraft aligned with these bridges&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;They are not&lt;/strong&gt; (but read on)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are aligned to a point on the concrete, not to the jetbridge(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is the jetbridge itself that carries out the final alignment to the aircraft door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jetbridges are actually motor vehicles with wheels, tyres, motors and (often) steering. It just happens that their rear end is tethered and their bodies articulate and/or telescope to accomodate the motion at the &quot;front&quot; end..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You &lt;a href=&quot;https://www.youtube.com/watch?v=TzwpV0LVniQ&quot; rel=&quot;noreferrer&quot;&gt;drive one&lt;/a&gt; using a set of controls at the end furthest from the terminal building&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.flickr.com/photos/97489578@N00/7578649684&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GkdSg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;sub&gt;-jet bridge controls&lt;/sub&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://instatagphoto.com/jetbridge/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qF9UG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;sub&gt;- driving a jet bridge&lt;/sub&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe some also have what is effectively variable height suspension like old Citroens (except I imagine it is hydraulic or jack-screw).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is driven to the terminal so the nose wheel follows a  guide line and stops at a marking appropriate for the aircraft type. Then the jet bridge is &lt;a href=&quot;https://www.youtube.com/watch?v=R7_1zK9Mq8c&quot; rel=&quot;noreferrer&quot;&gt;driven&lt;/a&gt; up to the aircraft door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft is gradually burdened with self-loading freight and sinks on it's suspension, the jetbridge metaphorically &lt;a href=&quot;http://www.core77.com/posts/25999/what-gains-50000-pounds-in-15-minutes-25999&quot; rel=&quot;noreferrer&quot;&gt;bends its knees&lt;/a&gt; so that the SLF don't trip up or fall into the aircraft. That is, the jetbridge maintains alignment, the aircraft is pretty passive in the job of alignment.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have to admit I didn't notice these jetbridge controls for many years as I was usually either busy rushing to my seat or busy rushing to the baggage reclaim. One time there was a delay at the aircraft door that was long enough for my bored gaze to alight on the controls and for the thought to briefly wander across my mind - &quot;I wonder what would happen if I pressed that ...&quot;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-05T16:05:04.390" LastActivityDate="2015-06-05T16:05:04.390" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15467" PostTypeId="2" ParentId="15452" CreationDate="2015-06-05T14:42:09.433" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How does adding more options for engines for potential customers act as an advantage for the Aircraft Manufacturer?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are a couple of ways of looking at this&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why new options?&lt;/li&gt;&#xA;&lt;li&gt;Why multiple options&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Change&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The A320 has been around a while, engines have improved a lot and newer types of engine exist now that were not available before, even though the A320 type airframe is still competetive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Airbus, new choice of engines allow for&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lower fuel costs&lt;/li&gt;&#xA;&lt;li&gt;Lower maintenance costs&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus is working on offering a new engine for the A320 known as the New Engine Option (NEO). The choice for new engines include the CFM International LEAP-X and the Pratt &amp;amp; Whitney PW1400G/PW1500G. The new engines will burn 16% less fuel: the actual fuel gain on an A320 installation will be slightly less, since 1-2% is typically lost upon installation on an existing aircraft. Airbus CEO said to be &quot;comfortable&quot; with the projections of 20% lower maintenance cost for the Pratt &amp;amp; Whitney's PW1000G family, compared with today's engines. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.a320neo.com/&quot;&gt;Airbus&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Choice&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Speculating a little: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The people who buy and operate aircraft like having a choice of engine manufacturers. It helps keep the engine market competitive and it means they can, if they want, operate a range of aircraft all using engines from one maker - potentially allowing for savings in engine maintenance infrastructure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft operators sometimes don't actually buy engines with their aircraft, they buy thrust from an engine maker and the engine maker (effectively) install their engines on the operators aircraft. The engines might remain the property of the maker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may also be that aircraft makers don't wish the future of their aircraft to be tied to a single supplier of engines. It makes negotiating harder and it makes their future prosperity dependent on the continued existence of one manufacturer.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-06-05T14:42:09.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15468" PostTypeId="2" ParentId="15452" CreationDate="2015-06-05T15:04:51.740" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How does adding more options for engines for potential customers act as an advantage for the Aircraft Manufacturer?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The primary reason for adding a &lt;em&gt;new&lt;/em&gt; engine option is to increase performance. As technology improves, engines get more efficient, so putting new engines on a plane can substantially improve the efficiency of the plane. Both the &lt;a href=&quot;http://en.wikipedia.org/wiki/CFM_International_LEAP&quot; rel=&quot;nofollow&quot;&gt;LEAP-1A&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW1000G&quot; rel=&quot;nofollow&quot;&gt;PW1000G&lt;/a&gt; engines offered on the A320neo claim a 15% fuel burn reduction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary reason for offering &lt;em&gt;multiple&lt;/em&gt; engine options is to give the customer choice. Each engine has slightly different thrust, fuel burn, weight, and maintenance requirements. Some airlines may want to stick with certain engine manufacturers to simplify maintenance.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why wouldn't the manufacturer optimize its plane for one engine specifically, to give best performance and roll out the plane like that?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sometimes they do. The 737, since the Classic series, has only had the CFM56 engine option. The new &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;nofollow&quot;&gt;737 MAX&lt;/a&gt; will only have the CFM LEAP option. Business jets will also tend to only have one engine option. The &lt;a href=&quot;http://en.wikipedia.org/wiki/Boeing_777X&quot; rel=&quot;nofollow&quot;&gt;777X&lt;/a&gt; in development plans on only offering the GE9X engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The challenge is not really in optimizing the plane for one engine. Most of the plane doesn't care much what kind of engine is on it. Although there will be some points of compromise, the parts that are specific to one engine type can be designed separately, and installed based on which option the customer chooses. Creating designs for more engines is more work, which the manufacturer will have to weigh based on the benefit that more options will offer.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-06-05T15:04:51.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15469" PostTypeId="2" ParentId="15452" CreationDate="2015-06-05T15:10:14.100" Score="2" Body="&lt;p&gt;Well, let's take a look, what are the advantages of having a choice of engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A320neo is set to offer engines from two different manufacturers: the CFM International Leap 1A, and the Pratt &amp;amp; Whitney PW1100G. These families of engines are designed to be more fuel-efficient, and what ever more &quot;efficients&quot; there are.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does adding more options for engines for potential customers act as an advantage for the Aircraft Manufacturer?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Let's take a look at this: My friend lives in New York, my cousin lives in Amsterdam, I live in Toronto. What happens if I want to visit any of them, what happens if I want to see all of them? That would be some very expensive flights...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines don't want a wide variety of things in their inventory either. Take a look at maintenance. Some people can work on one engine, while other people can't. Then, you might have unfamiliar technologies. There would be a lot of change, I'd need different people for each engine. That would be very costly too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airlines that already have a &quot;predominant&quot; engine in their inventory, they'd want to stick to it. They're familiar with the technology, the basic systems, and they have engineers who can work on this too. This is why many airlines stick to a sole engine manufacturer, or more importantly, a single airplane manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having different choices means you can serve a wider market. If I see that I can get this plane with my favourite engine, it's a double win! :)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why wouldn't the manufacturer optimize its plane for one engine specifically, to give best performance and roll out the plane like that?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many manufacturers already do. If you were to look at the Bombardier CSeries, the exclusive engine is the PW1100G. Engines aren't the biggest part. If an engine can do it's job, deliver fuel efficiency and so on... Then why shouldn't we have it as an option? If it's feasible to have more than one engine on a plane, then they'll go for it.&lt;/p&gt;&#xA;" OwnerUserId="7670" LastActivityDate="2015-06-05T15:10:14.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15470" PostTypeId="2" ParentId="15448" CreationDate="2015-06-05T15:29:36.337" Score="2" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An operator of a certified airport is required to conduct airport operations according to an Airport Operations Manual.&lt;/li&gt;&#xA;&lt;li&gt;This manual &lt;strong&gt;must &lt;em&gt;enumerate&lt;/em&gt;&lt;/strong&gt; the facilities offered by the airport.&lt;/li&gt;&#xA;&lt;li&gt;An important aspect of the manual is to &lt;em&gt;describe&lt;/em&gt; how airport safety and emergencies are managed, and by whom. Note that the obligations for safety are not specific to airports, but apply to any aerodrome. what is required for an airport is to write in the AOM how they are implemented.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So the difference between an aerodrome and an airport is not about the facilities or the equipment, it's about &lt;em&gt;how&lt;/em&gt; it is operated and &lt;em&gt;who&lt;/em&gt; checks it is done as intended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indeed &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp312-chapter8-menu-938.htm&quot; rel=&quot;nofollow&quot;&gt;some equipments are required&lt;/a&gt; at an airport (e.g. markings, lights and signs) but they are not specific to airports, they apply to &lt;em&gt;all&lt;/em&gt; aerodromes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Layman language&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aerodrome&lt;/strong&gt; usually refers to the possibility for aircrafts to land and take-off. This is the point of view of a &lt;strong&gt;pilot&lt;/strong&gt; with needs to takeoff and land. &lt;em&gt;The word aerodrome is derived from the Greek words aeras (αέρας), &quot;air&quot; and dromos (δρόμος), &quot;road&quot; or &quot;course&quot;, literally meaning &quot;air course&quot;&lt;/em&gt; (&lt;a href=&quot;http://en.wikipedia.org/wiki/Aerodrome#Etymology&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Airport&lt;/strong&gt; usually refers to an aerodrome with passengers or freight facilities. This is the angle of view of an &lt;strong&gt;airline&lt;/strong&gt; conducting business. In Canada there are obligations associated with running an airport.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;International airport&lt;/strong&gt; usually refers to an airport with &lt;strong&gt;customs and immigration services&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aeronautical language&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the aeronautical information, a Canadian airport remains an aerodrome. E.g. a &lt;a href=&quot;http://www.navcanada.ca/EN/products-and-services/Pages/AIP-part-3-current.aspx&quot; rel=&quot;nofollow&quot;&gt;list of aerodromes&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Canadian authorities language&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Canada, an airline making business with air transportation must operate at aerodromes holding an &lt;em&gt;airport certificate&lt;/em&gt;, aerodromes referred to by the Canadian authorities as &lt;em&gt;airports&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/sor-96-433/fulltext.html&quot; rel=&quot;nofollow&quot;&gt;Canadian Aviation Regulations&lt;/a&gt; “airport” means:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an aerodrome in respect of which an airport certificate issued under&#xA;  Subpart 2 of Part III is in force.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Issuance of the certificate is described at section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.03&quot; rel=&quot;nofollow&quot;&gt;302.03&lt;/a&gt;, and obligations for the airport operator are described at section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.07&quot; rel=&quot;nofollow&quot;&gt;302.07&lt;/a&gt;. This is a very long list of obligations. An Airport Operations Manual is required, and described at section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.08&quot; rel=&quot;nofollow&quot;&gt;302.08&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary of section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.07&quot; rel=&quot;nofollow&quot;&gt;302.07&lt;/a&gt; - The operator of an airport shall...&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Comply with the &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp312-menu-4765.htm&quot; rel=&quot;nofollow&quot;&gt;standards set out in the &lt;strong&gt;aerodrome&lt;/strong&gt; standards and recommended practices publications&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Inspect the airport [...] after any aviation occurrence...&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Assign duties on the movement area and any other area [...] only to employees who have successfully completed a safety-related initial&#xA;  training course on human and organizational factors.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary of section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.08&quot; rel=&quot;nofollow&quot;&gt;302.08&lt;/a&gt; - The Airport Operations Manual must contain...&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... all the informations necessary for the authorities to verify that&#xA;  the airport meets the &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp312-menu-4765.htm&quot; rel=&quot;nofollow&quot;&gt;applicable standards&lt;/a&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Physical characteristics&lt;/li&gt;&#xA;  &lt;li&gt;Obstacle limitation surfaces&lt;/li&gt;&#xA;  &lt;li&gt;Declared distances&lt;/li&gt;&#xA;  &lt;li&gt;Lighting, markers, markings, signs&lt;/li&gt;&#xA;  &lt;li&gt;Access to the movement area and control procedures...&lt;/li&gt;&#xA;  &lt;li&gt;Enumeration of the facilities and services provided [...] including air traffic services and aeronautical information and communication&#xA;  services, navigation aids, and aviation weather services&lt;/li&gt;&#xA;  &lt;li&gt;Emergency response measures&lt;/li&gt;&#xA;  &lt;li&gt;Airport safety measures&lt;/li&gt;&#xA;  &lt;li&gt;Safety management system required under section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-107.02&quot; rel=&quot;nofollow&quot;&gt;107.02&lt;/a&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Description of the safety management system's components specified in section &lt;a href=&quot;http://laws-lois.justice.gc.ca/eng/regulations/SOR-96-433/FullText.html#s-302.502&quot; rel=&quot;nofollow&quot;&gt;302.502&lt;/a&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;The operator of an airport &lt;strong&gt;shall&lt;/strong&gt; operate the airport in accordance&#xA;  with the Airport Operations Manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ICAO publishes a set of &lt;a href=&quot;http://en.wikipedia.org/wiki/Standards_And_Recommended_Practices&quot; rel=&quot;nofollow&quot;&gt;standards and recommended practices (SARPs)&lt;/a&gt;, including &lt;em&gt;Annex 14 — Aerodromes, Volume I — Aerodrome Design and Operations&lt;/em&gt;. Standards are fully enforced by ICAO members, recommended practices are encouraged but still optional for members.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;&lt;strong&gt;Summary&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In Canada, airlines are required to conduct business &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/standards/commerce-menu.htm&quot; rel=&quot;nofollow&quot;&gt;according to specific rules&lt;/a&gt; regarding aircrafts, passengers, security, etc. One of these obligations is to use airports holding a valid certificate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airport operators are required to conduct operations according to the practices listed in related publications. They must use an Airport Operations Manual describing how these practices are implemented. The authorities deliver the airport certificate based on this manual, and on-site inspection.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airports operators are required to install &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp312-chapter8-8-8-4702.htm#8.8.1&quot; rel=&quot;nofollow&quot;&gt;equipments such markings&lt;/a&gt;, but this is valid for any aerodrome.&lt;/li&gt;&#xA;&lt;li&gt;Airport operators are not required to offer such services as immigration, ATC, weather station, refueling, gateways, etc, however they are required to publish, in the Airport Operations Manual, which services are available.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's up to airlines to select and use the appropriate airports, according to their needs and legal obligations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-06-06T12:55:04.167" LastActivityDate="2015-06-06T12:55:04.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15471" PostTypeId="2" ParentId="15337" CreationDate="2015-06-05T16:00:09.900" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;let's say a friendly aircraft were to fly in front of you when you had sight lock turned on; would the missile fire at the friendly aircraft, or is there a piece of technology in the friendly aircraft which registers that it's with you?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is indeed an important piece of technology which &quot;registers that with you&quot;.  The piece of technology is called an &lt;strong&gt;IFF&lt;/strong&gt;, which stands for &lt;strong&gt;Identification Friend of Foe&lt;/strong&gt;.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Identification_friend_or_foe&quot; rel=&quot;noreferrer&quot;&gt;Read more about the IFF here.&lt;/a&gt;     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question &lt;code&gt;would the missile fire at the friendly aircraft&lt;/code&gt; implies the missile is making the decision to fire autonomously, but this was not the case in the F-16 as recently as 10 years ago.  Most US fighter aircraft (and probably fighter aircraft of other countries) give a great deal of control of the missile to the pilot.  The idea behind this is autonomous systems sometimes behave in unintended ways, and a missile shot is just too important not to be directly controlled by the pilot during at least the initial phases, such as during the decision to fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the decision to fire is made and the missile leaves the firing aircraft, there are autonomous systems which eventually take over (sometimes immediately).  However, the sky is large, and planes are small.  The likelihood that a friendly aircraft would accidentally become the new target after an enemy was originally targeted is very low.  Sometimes concern for such as missile lock transfer is a consideration for close-range shots.  However, the vast majority of missile shots in a modern air battle engagement occur in situations where the aircraft are separated by large distances.  So let's talk about those shots occurring far away, called &lt;strong&gt;BVR&lt;/strong&gt; shots, or &lt;strong&gt;Beyond Visual Range&lt;/strong&gt; missile shots.  &lt;a href=&quot;http://en.wikipedia.org/wiki/Beyond-visual-range_missile&quot; rel=&quot;noreferrer&quot;&gt;Read more about BVR here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The decision to employ a missile by shooting beyond visual range is analogous to the decision of a jury to convict someone in court - except the decision is made by perhaps one or two people (pilot and/or weapons officer) in just a few seconds using some rules of engagement.  The court analogy works because the decision really is a judgement call, and there are many pieces of evidence to weigh in the decision.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technology is a pilot's best friend when making this decision.  IFF is probably considered the golden standard for shooting a hostile aircraft, however not all fighters have IFF interrogation capability on board.  Even fighters with IFF interrogation capability may rely on other information as well.  Is the firing aircraft on one side of a border or demarcation line / political state border while the potentially hostile aircraft is on the other line, perhaps inside another nation's borders?  So location can help.  However, during a fight where aircraft are mixed together, location becomes less helpful.  There are other technological means for determining that an aircraft is hostile, but virtually all of those means are US state secrets and therefore cannot be discussed on StackExchange (unfortunately).  Let's focus on IFF since IFF is the most useful tool, and the basic functionality of IFF is not a secret.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every friendly aircraft is programmed before flight with a secret cryptographic code prior to takeoff.  The pilot is not involved in this programming.  Instead, someone from the maintenance unit goes around to all the aircraft perhaps an hour or two prior to takeoff and loads the secret code into the jet's IFF computer system.  When the pilot shows up, the IFF code is set and ready to go.  Part of the pre-flight check in a fighter aircraft is to check the IFF to make sure the code is loaded properly.  If that sounds cool, it's because it is cool.  Civilian pilots don't have a step in their pre-flight checklist to make sure a cryptographic key is loaded correctly to prevent them from getting shot down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cryptographic system involving the IFF is analogous to a digital certificate used in internet communication.  How do you know if Amazon.com is really Amazon.com and not some spoof?  How do you know you are actually talking with your bank online and not some impostor?  Your browser uses cryptography to interrogate the server at Amazon.com, and if Amazon didn't use a valid key to encrypt its messages, then your browser will tell you it can't verify Amazon is authentic.  There are two parts to this system: the interrogator and the responder.  The responder in the IFF system is called a &lt;strong&gt;Transponder&lt;/strong&gt; in the civilian world, because it &quot;transmits&quot; a &quot;response&quot;.  The military just calls it an IFF because the military loves acronyms.  As mentioned before, not all fighter aicraft have IFF interogators.  However, every aircraft in the battle space has an IFF responder.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;could that potentially be used against you in modern day aerial warfare?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Could defeating the IFF system be used against you?  If I had knowledge of such a thing occurring, then I certainly could not discuss it here.  I will respond to this hypothetical question with a question:  Could attacking and exploiting any cryptographic security system cause problems for the users who depend upon that system to make decisions?  I'll leave that up to your imagination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This abstract discussion of some of the technology behind modern rules of engagement for fighter aircraft can be dry.  So I'll end my answer with a photo of the button an F-16 pilot pushes to fire the missile (it's not the trigger - the trigger fires the gun).  Maybe off topic, but there is research indicating people remember better when learning with pictures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tTjFy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2141" LastActivityDate="2015-06-05T16:00:09.900" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15472" PostTypeId="1" AcceptedAnswerId="15473" CreationDate="2015-06-05T17:23:46.420" Score="16" ViewCount="2575" Body="&lt;p&gt;I saw this image posted in &lt;a href=&quot;https://aviation.stackexchange.com/a/15463/65&quot;&gt;another question&lt;/a&gt;. &lt;strong&gt;What airport is this?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OkmsQ.jpg&quot; alt=&quot;747 being marshaled beneath a passenger bridge&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-05T18:48:15.387" Title="What airport has this walkway over a taxiway?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15473" PostTypeId="2" ParentId="15472" CreationDate="2015-06-05T17:43:47.610" Score="14" Body="&lt;p&gt;This image was taken at &lt;a href=&quot;http://www.telegraph.co.uk/travel/travelnews/2585628/Passengers-warned-BAA-break-up-will-not-lead-to-fare-cuts.html&quot;&gt;London Gatwick&lt;/a&gt;. The bridge connects two portions of the North Terminal, right next to where the North Terminal is labeled on this map:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/73e7L.jpg&quot; alt=&quot;Map of London Gatwick Airport&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;London Gatwick &lt;a href=&quot;http://www.gatwickairport.com/business-community/about-gatwick/at-a-glance/history/&quot;&gt;claims to be the first airport&lt;/a&gt; to have such a feature. As can be seen in the photo, it is &lt;a href=&quot;http://www.airport-technology.com/projects/pier6/&quot;&gt;the largest in the world&lt;/a&gt;, high enough for a 747 to pass underneath.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not the only airport to have such a feature, though. &lt;a href=&quot;http://en.wikipedia.org/wiki/Denver_International_Airport&quot;&gt;Denver International&lt;/a&gt; also has a &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/e/eb/DEN-_PED_BRIDGE.JPG&quot;&gt;bridge (picture)&lt;/a&gt; over the taxiway connecting the terminal building with Concourse A. This one is not as high as the bridge at Gatwick and can't clear anything larger than a 737.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="65" LastEditDate="2015-06-05T18:48:15.387" LastActivityDate="2015-06-05T18:48:15.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15474" PostTypeId="2" ParentId="15462" CreationDate="2015-06-05T18:48:36.847" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.flyingmag.com/aircraft/helicopters/s-tec-introduces-robinson-r44-autopilot&quot; rel=&quot;nofollow&quot;&gt;This Article&lt;/a&gt; about &lt;a href=&quot;http://genesys-aerosystems.com/product-category/helisas-autopilot-and-stability-augmentation-system&quot; rel=&quot;nofollow&quot;&gt;HeliSAS&lt;/a&gt; seems to elude to the fact they can and certified systems exist. The &lt;a href=&quot;https://www.airbushelicopters.com/website/en/ref/H145M_47.html&quot; rel=&quot;nofollow&quot;&gt;specs of this helicopter&lt;/a&gt; list it as having &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...Airbus Helicopters’ advanced Helionix® avionics suite with a 4-axis&#xA;  digital autopilot&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-05T18:48:36.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15475" PostTypeId="1" AcceptedAnswerId="15481" CreationDate="2015-06-05T19:51:18.000" Score="17" ViewCount="740" Body="&lt;p&gt;Most of the &lt;a href=&quot;http://en.wikipedia.org/wiki/TCAS&quot; rel=&quot;noreferrer&quot;&gt;information I've seen&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/a/1888/4269&quot;&gt;about TCAS&lt;/a&gt; talks about only two aircraft being involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's pretty unlikely, although far from impossible that situations involving three or more aircraft may arise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In such situations is TCAS expected to detect the situation and offer sensible advice still? Or are all bets off and a series of confusing and conflicting advice the most likely outcome?&lt;/p&gt;&#xA;" OwnerUserId="4269" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-06-30T16:41:24.123" Title="Can TCAS cope with situations involving more than two aircraft?" Tags="&lt;safety&gt;&lt;tcas&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15476" PostTypeId="2" ParentId="15462" CreationDate="2015-06-05T19:53:50.243" Score="10" Body="&lt;p&gt;Yes, helicopters can be fitted with autopilots. Some are very simple, others are quite advanced. The more advanced ones can, for instance, follow a pre-programmed route, climb/descent to a pre-selected altitude, fly an ILS approach, perform a go-around automatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not ordinarily found in small helicopters due to cost and lack of necessity. All modern offshore helicopters that I've encountered have them and they are used extensively. Usually they are engaged shortly after take-off and disengaged shortly before landing.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastEditorUserId="8771" LastEditDate="2015-06-05T20:15:41.540" LastActivityDate="2015-06-05T20:15:41.540" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15477" PostTypeId="1" AcceptedAnswerId="15546" CreationDate="2015-06-05T20:06:28.923" Score="7" ViewCount="833" Body="&lt;p&gt;NASA and the &lt;a href=&quot;http://history.nasa.gov/SP-440/ch8-4.htm&quot;&gt;French&lt;/a&gt; aerospace agency have conducted research into magnetic suspension and balancing systems (MSBS) to suspend models during wind tunnel tests, like &lt;a href=&quot;https://www.youtube.com/playlist?list=PLDC72CADE079922A4&quot;&gt;this&lt;/a&gt; system in South Korea.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Where did the NASA and ONERA research lead?&lt;/li&gt;&#xA;&lt;li&gt;If MSBS reduces interference from the springs and arms that usually hold models, why don't all wind tunnels use this technology? What are the disadvantages?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Also, can somebody create a wind-tunnel or wind-tunnel-testing tag?&lt;/p&gt;&#xA;" OwnerUserId="4432" LastEditorUserId="1696" LastEditDate="2015-06-05T20:10:34.817" LastActivityDate="2015-06-08T19:45:18.033" Title="Why don't all wind tunnels use magnets to suspend models?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wind-tunnel&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15478" PostTypeId="5" CreationDate="2015-06-05T20:12:40.367" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-05T20:12:40.367" LastActivityDate="2015-06-05T20:12:40.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15479" PostTypeId="4" CreationDate="2015-06-05T20:12:40.367" Score="0" Body="a route is usually traveling from point A to point B via a predetermined path" OwnerDisplayName="user8732" LastEditorDisplayName="user8732" LastEditDate="2015-06-05T21:22:42.123" LastActivityDate="2015-06-05T21:22:42.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15480" PostTypeId="2" ParentId="15406" CreationDate="2015-06-05T20:31:12.933" Score="4" Body="&lt;p&gt;VERICOR POWER SYSTEMS has a patent for these valves, number &lt;code&gt;US 6357216 B1&lt;/code&gt; and title &lt;code&gt;Flashback control for a gas turbine engine combustor having an air bypass system &lt;/code&gt;&lt;/p&gt;&#xA;&lt;p&gt;The patent includes the following image:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LSPAz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LSPAz.png&quot; alt=&quot;value diagram&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;SUMMARY OF THE INVENTION&lt;/p&gt;&#xA;&lt;p&gt;An object of the present invention is to provide for a control and method for arresting flashback in a gas turbine engine combustion system having a venturi for delivering a mixture of air and fuel to a combustion chamber and a valve for controlling the amount of air flowing to the venturi.&lt;/p&gt;&#xA;&lt;p&gt;The present invention achieves this object by providing a flashback control system and method having a flashback detection routine, a valve position trim routine, and a reference flame temperature adjustment routine. The flashback detection routine detects a flashback in the venturi by comparing the temperature at the venturi to the temperature of the air entering the valve. The valve position trim routine receives this flashback signal and in response causes the valve to open until the flashback is arrested. Finally, to prevent the flashback from recurring, the reference flame temperature adjustment routine adjusts a reference flame temperature in the control system so as to prevent the valve from returning to the position at which the flashback occurred.&lt;/p&gt;&#xA;&lt;p&gt;These and other objects, features and advantages of the present invention, are specifically set forth in, or will become apparent from, the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The patent can be viewed here on &lt;a href=&quot;https://www.google.com/patents/US6357216&quot; rel=&quot;nofollow noreferrer&quot;&gt;Google patents list&lt;/a&gt;, however, it has expired.&lt;/p&gt;&#xA;" OwnerUserId="8300" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-06-15T16:51:27.613" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="15481" PostTypeId="2" ParentId="15475" CreationDate="2015-06-05T20:48:33.343" Score="17" Body="&lt;p&gt;TCAS can deal with conflicts with multiple aircraft, a so called Multiple Threat Encounter. It will attempt to resolve the conflict but it will be limited in its options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples of a MTE are rare, one case I can point to is &lt;a href=&quot;http://avherald.com/h?article=458f61d3&quot;&gt;this incident&lt;/a&gt; involving an aircraft turning into the approach stream between two aircraft instead of following the last in line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ll.mit.edu/mission/aviation/publications/publication-files/atc-reports/Billingsley_2009_ATC-359_WW-18718.pdf&quot;&gt;MIT Lincoln lab&lt;/a&gt; has reported on MTEs and the TCAS algorithm performance in 2009. They report the majority of MTEs involved three aircraft, but mention one TCAS MTE involving seven aircraft.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-06T09:49:14.383" LastActivityDate="2015-06-06T09:49:14.383" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15482" PostTypeId="2" ParentId="15382" CreationDate="2015-06-05T20:50:51.937" Score="2" Body="&lt;p&gt;Within commercial civilian flying the mission objective is to land safely at a destination. In operational flying in a 'deployment zone' the mission is to do many other things before you land somewhere safely. There are so many more factors to consider than just flying from A to B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Areas of recent combat, rising threats, low-level flight, areas where fighting is imminent, mountain flying, attempting to minimise the impact on local population when you fly over their houses/vilages/cities, proximity to other air-assets that fly in the same mission. Just to name a few.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even seemingly 'airline' types of transport in the military do have to consider many more factors during take-off and landing in a war-zone. They don't come with missile self-protection systems for fun.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-05T20:50:51.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15483" PostTypeId="2" ParentId="15309" CreationDate="2015-06-05T21:13:14.813" Score="4" Body="&lt;p&gt;Flying with NVG is quite different from normal flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With NVG on, your field of vision is very limited. It is about 40º wide instead of over 180º. This needs training to get used to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You get the feeling that with NVG, you can see everything without limits, whereas in reality, the level of detail you see at night with NVG is more close to legal blindness if that was your quality of vision during the day. There are also several phenomenon that if you are not trained to recognise, you might fly into a hill that you didn't think was there, because it was not clearly visible due to a larger hill behind it (lack of contrast between the two objects in the field of view) or an object in the shadow of a hill or mountain. High tension wires, trees that don't have leaves, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you have two used toilet-rolls available, stick them together to make make-shift binoculars, but them on your head like an NVG (try to block your peripheral vision past the tubes to prevent cheating) and try to walk through familiar territory (like where you live) and see how well you do. Then, if you are bold enough to do that, try to cycle like that. I would not recommend you do this while driving unless it is in an empty parking lot and you are trying to avoid pylons or some other soft non-living obstacle. Once you get the idea, imagine doing that at night while presented with much lower quality imagery. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no knowledge of the legality of civilian NVG operations&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-05T21:13:14.813" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15484" PostTypeId="1" CreationDate="2015-06-05T21:39:29.030" Score="3" ViewCount="686" Body="&lt;p&gt;I'd like to rephrase the question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often I forward-slip on final right right rudder.  During this time, I use the ailerons to keep the aircraft headed down the center-line; the aircraft's bank varies slightly from left wing down, to right wing down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point during this procedure, I have right rudder in and a slight right bank.  I believe this is a skid; Is this something I should worry about?  I would very much like to avoid skidding at all times, especially on final!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Previous question, for reference:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming there is a crosswind and the pilot executes a crabbed approach, during the flare the pilot is going to have to use the rudders to avoid a side-load.   My understanding is that this will result in an uncoordinated flying condition and is prone to stall-spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this (the flare) does not seem to be much of an issue among pilots.  What am I missing?  How is this any different than a skid?&lt;/p&gt;&#xA;" OwnerUserId="7177" LastEditorUserId="7177" LastEditDate="2015-06-12T22:34:36.163" LastActivityDate="2015-06-12T22:34:36.163" Title="Flare: low, slow, and uncoordinated?" Tags="&lt;landing&gt;&lt;spins&gt;&lt;crosswind&gt;" AnswerCount="3" CommentCount="3" ClosedDate="2015-06-08T14:49:11.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="15485" PostTypeId="2" ParentId="15484" CreationDate="2015-06-05T22:26:42.920" Score="7" Body="&lt;p&gt;Crosswind landings are always uncoordinated. I'm not familiar with big jets, but I believe they simply kick the rudder to align the nose with the runway and let the momentum carry it in the right direction until it touches down, but I might be mistaken here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a smaller aircraft (like a piston single) you're taught to drop a wing into the wind and effectively land in a side slip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is all perfectly safe, the dangerous situation you're talking about is a skidding turn, where you apply too much bottom rudder, letting the 'inner' wing slow down to the point of stalling. This only applies to an actual turn however, if you're flying straight, coordinated or not, there's still more or less the same airflow over the wings. You could however experience other aerodynamic effects where fuselage and airfoils effectively perturb the air for other airfoils and might cause a wing drop or pitch change, but it depends on the properties of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2015-06-05T22:26:42.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15486" PostTypeId="2" ParentId="3608" CreationDate="2015-06-05T22:30:56.577" Score="44" Body="&lt;p&gt;There are no language recommendations or requirements, other than what is sensible given the verification requirements in the various standards (e.g., DO-178B/C). For the highest design assurance levels, the generated code must be inspected down at the op-code level to ensure no known processor gotchas are invoked. You also end up having to test every part of every conditional, both the true and the false sides, and ensure that no jump instructions will take you someplace where you didn't expect it to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For these reasons, the big three languages in use in embedded avionics today are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;C++ (as a better C. The OO nature is often used only sparingly. Things like polymorphism are just too expensive to verify)&lt;/li&gt;&#xA;&lt;li&gt;Ada (You may not like it, but a TON of current avionics are written in Ada, and are currently being maintained and updated with new features)&lt;/li&gt;&#xA;&lt;li&gt;C - As close to the hardware as you want to get and still be highly productive (not intending to offend anyone who is productive in something else)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Assembler is frequently used for specific needs, but it would not be used to a greater degree than one of the above-mentioned languages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes these languages ideal for avionics is that they are relatively close to the hardware and memory structure, not too abstract. Their tools are mature and well-known. People have years of experience certifying software written in them. And there are lots of programmers who can get up to speed in them quickly (Yes, even Ada). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-safety critical software, both on and off the aircraft, will be written in any of the big languages of the day: Java, C#, VB, C, C++, Python, Perl, Ruby, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;iPads are becoming useful inside the cockpit and are approved in limited situations. iOS apps are written in Objective-C, C, C++, and increasingly, Swift (Apple's new language).&lt;/p&gt;&#xA;" OwnerUserId="8772" LastEditorUserId="2650" LastEditDate="2016-06-10T10:59:41.920" LastActivityDate="2016-06-10T10:59:41.920" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15487" PostTypeId="1" CreationDate="2015-06-05T22:34:15.853" Score="9" ViewCount="481" Body="&lt;p&gt;Being near an emergency exit improves considerably the survival chances after an accident. Why not put one exit at every 5 rows?&lt;/p&gt;&#xA;" OwnerUserId="8773" LastEditorUserId="97" LastEditDate="2015-06-07T12:59:44.697" LastActivityDate="2015-06-07T12:59:44.697" Title="Couldn't airplanes have more emergency exits?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;passenger&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15488" PostTypeId="2" ParentId="15487" CreationDate="2015-06-05T23:33:55.440" Score="15" Body="&lt;p&gt;Money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doors cost (and weight) a &lt;em&gt;lot&lt;/em&gt; more than plain aluminum panels. And the exit row on larger planes usually consumes one row of seats. So lets say we are on a 767 and take out every 6th outer row, that's 5 extra exit rows and 20 fewer paying seats, or $6,000 less per flight which quickly adds up to nearly the cost of the aircraft itself over its service life. And that's quite a lot of money for something that will very likely never be used. Remember that exit doors only help if the plane crash-lands in a mostly upright position. Severe crashes often add large exits by splitting the fuselage open, and lawn-dart mode accidents don't leave too many survivors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flying public has indicated that they are very interested in ticket price, but somewhat less interested in the safety factor. The current accident rates appear to be acceptable to those paying for the service.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1467" LastEditDate="2015-06-06T08:59:39.723" LastActivityDate="2015-06-06T08:59:39.723" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15489" PostTypeId="2" ParentId="12054" CreationDate="2015-06-06T00:33:50.030" Score="1" Body="&lt;p&gt;If your frequency is accurate then it uses 25 khz spacing. VHF channels can be spaced at 100khz, 50 khz, 25 khz, 12.5 or 8.333 - hence the more decimal places on the dial.&#xA;I think you might have picked up a marker beacon based on someone elses analysis. Basically there are three tones at 1020 hz / 1300 hz and 3khz that tell a pilot how far he is from the runway. &#xA;I don't think you would get the signal from 30 miles though, but you never know. &#xA;Also the 150hz tone can be from the localizer - which will definitely be valid over 30 miles. there are two tones - one at 90 hz and the other at 150 hz. &#xA;Obviously these are modulated on the carrier frequency, and these are part of the ILS system.&#xA;I have a feeling you don't have the exact frequency but see if it is stronger&#xA;at 110.55, if it is then this is the localizer frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 100khz digit is odd for localizer frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps&lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2015-06-06T00:33:50.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15490" PostTypeId="2" ParentId="15484" CreationDate="2015-06-06T02:35:20.400" Score="5" Body="&lt;p&gt;Basically it's not an issue because we don't get down to a speed where we need to worry too much about a spin.  It takes more than uncoordinated flight to induce a spin.  You have to have a stall first.  You don't stall as long as there's adequate airflow over the wings.  As long as you don't get below ${V_S}_0$ (with flaps extended) on both wings, even if you're cross controlled, you're okay.&lt;/p&gt;&#xA;" OwnerUserId="6840" LastEditorUserId="2143" LastEditDate="2015-06-06T15:38:57.563" LastActivityDate="2015-06-06T15:38:57.563" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15491" PostTypeId="2" ParentId="15484" CreationDate="2015-06-06T11:02:23.287" Score="4" Body="&lt;p&gt;Slipping during a descent is not particularly likely to cause a stall because both wings are are sufficiently unloaded that they're not likely to exceed their critical angle of attack. Forward slips to a landing are, in fact, a very useful skill to have, especially for pilots flying very light singles (possibly without constant speed props or even flaps) and one that can allow pilots much more flexibility during landings and engine-out emergencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You do need to be careful not to flare too soon, as that might cause your airspeed to bleed off to the point were you will either begin to sink too rapidly and touch down hard or, in a really bad outcome, actually induce a stall and run the risk of losing control of the aircraft. It's probably worth noting that this is a concern for normal landings as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to that, even if you were to stall the aircraft while in a slip, the aircraft will snap towards the outer, raised wing, reducing the angle of bank (most modern light trainers will generally just return to a more or less wings-level attitude) and making for a much easier (and less harrowing) recovery. A stall during a skid, by comparison, will snap the aircraft towards the inside, lowered wing, and put it into the incipient phases of a spin (and will usually do so in a far more violent and surprising manner than you might be expecting, even if you've spun that aircraft before). This is a much more unpleasant experience (even in normally benign aircraft) and requires prompt and correct action in order to successfully recover.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-06-06T11:02:23.287" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15492" PostTypeId="5" CreationDate="2015-06-06T12:38:13.487" Score="0" Body="&lt;p&gt;The earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautic research, when many attempted to develop successful heavier-than-air flying machines. The wind tunnel was envisioned as a means of reversing the usual paradigm: instead of the air standing still and an object moving at speed through it, the same effect would be obtained if the object stood still and the air moved at speed past it. In that way a stationary observer could study the flying object in action, and could measure the aerodynamic forces being imposed on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tag could have questions about&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Wind Tunnel (Working and Concepts)&lt;/li&gt;&#xA;&lt;li&gt;Wind Tunnel testing methods and improvements regarding that&lt;/li&gt;&#xA;&lt;li&gt;Any other concept which has a relation to Wind Tunnels&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-07T02:02:20.460" LastActivityDate="2015-06-07T02:02:20.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15493" PostTypeId="4" CreationDate="2015-06-06T12:38:13.487" Score="0" Body="A wind tunnel is a tool used in aerodynamic research to study the effects of air moving past solid objects. A wind tunnel consists of a tubular passage with the object under test mounted in the middle. Air is made to move past the object by a powerful fan system or other means. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-06T14:06:22.447" LastActivityDate="2015-06-06T14:06:22.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15494" PostTypeId="2" ParentId="8089" CreationDate="2015-06-06T13:27:55.223" Score="0" Body="&lt;p&gt;An unducted fan or propfan is defined as a fan or fans being directly driven by a set of turbines, that is, no reduction gearbox. The unducted fan is essentially a turbofan with the fan being outside the nacelle, hence the term &quot;unducted.&quot; Early unducted fans were directly integrated onto the turbine section of the plant resulting in the fans being in the aft of the engine, however if you run a shaft to the front, as is done on a turbofan, it can be a tractor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A turboprop is defined as having a gearbox to connect the turbine section with the propeller.&lt;/p&gt;&#xA;" OwnerUserId="8777" LastActivityDate="2015-06-06T13:27:55.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15495" PostTypeId="1" AcceptedAnswerId="15501" CreationDate="2015-06-06T14:17:26.460" Score="18" ViewCount="6788" Body="&lt;p&gt;I read &lt;a href=&quot;https://aviation.stackexchange.com/questions/2354/why-are-planes-generally-painted-white&quot;&gt;Why are planes generally painted white?&lt;/a&gt;, and got interested in knowing, why don't &lt;a href=&quot;https://www.google.co.in/search?q=military+aircraft&amp;amp;num=20&amp;amp;safe=off&amp;amp;es_sm=93&amp;amp;source=lnms&amp;amp;tbm=isch&amp;amp;sa=X&amp;amp;ei=twBzVajFBZG9uAS4lYLwCA&amp;amp;ved=0CAcQ_AUoAQ&amp;amp;biw=1242&amp;amp;bih=606&quot; rel=&quot;nofollow noreferrer&quot;&gt;military aircraft&lt;/a&gt; follow this? Rather than the advantageous white, most of the military aircraft are rather painted pretty darker, green or black or some other color. Why is this done?&#xA;Probably, it is not for distinguishing military with civilian aircraft .Becuase, the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB4QFjAA&amp;amp;url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FRadar&amp;amp;ei=GEt0VdXEIs398QWBqoHQAw&amp;amp;usg=AFQjCNF7taBeh0AICHfjJju5fXar1LzGoA&amp;amp;sig2=cLJIpw3FUUpYXJ28ZiD99g&quot; rel=&quot;nofollow noreferrer&quot;&gt;RADAR&lt;/a&gt; knows which aircraft is what.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="14897" LastEditDate="2021-03-09T17:34:40.333" LastActivityDate="2021-03-09T17:34:40.333" Title="Why are military planes painted differently than civil planes?" Tags="&lt;military&gt;&lt;livery&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15496" PostTypeId="1" AcceptedAnswerId="15497" CreationDate="2015-06-06T15:37:13.233" Score="4" ViewCount="1995" Body="&lt;p&gt;I am very new to aviation and trying to understand how to calculate the actual range of an aircraft given real world wind conditions.  I understand from &lt;a href=&quot;https://aviation.stackexchange.com/a/13681/8389&quot;&gt;this related question&lt;/a&gt; that you need  30 minutes of reserve and that tailwind and headwind direction will obviously impact your range.  I've also heard that the altitude you fly at can impact your range because higher air is thinner and allows you to travel faster.  I also would assume that the aircraft load would impact range.  So my question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Given the theoretical range of an aircraft (i.e. from specs published &lt;a href=&quot;http://www.risingup.com/planespecs/&quot; rel=&quot;nofollow noreferrer&quot;&gt;at this site&lt;/a&gt;) how do you calculate how far the aircraft can actually travel at a given altitude, with a given load, and with current wind conditions?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-07-28T11:30:46.397" Title="How can the range of an aircraft be calculated given real wind conditions?" Tags="&lt;aircraft-performance&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15497" PostTypeId="2" ParentId="15496" CreationDate="2015-06-06T15:59:30.433" Score="8" Body="&lt;p&gt;The best answer: Use the charts in the respective Pilot's Operating Handbook (POH). There you should find correction factors for the parameters which influence aircraft range&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuel on board: The more, the better. But note that doubling fuel will not double range.&lt;/li&gt;&#xA;&lt;li&gt;Take-off mass: If you take no payload, the aircraft will produce less induced drag and reach a slightly higher range. See the chart below for an example.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp&quot;&gt;Wind&lt;/a&gt; enroute. Follow the link; the wind component parallel to your flight direction will change the range by the product of wind speed times flight time.&lt;/li&gt;&#xA;&lt;li&gt;Cruise &lt;a href=&quot;https://aviation.stackexchange.com/questions/4967/how-can-you-find-the-best-altitude-for-range-or-speed&quot;&gt;altitude&lt;/a&gt;: This depends on the type of engines, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;jets benefit more from altitude&lt;/a&gt; than &lt;a href=&quot;https://aviation.stackexchange.com/questions/991/how-do-i-determine-the-best-altitude-to-fly-for-fuel-economy&quot;&gt;propeller aircraft&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Temperature&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Generally, there should be a chart like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ufDIa.png&quot; alt=&quot;This is a typical payload-range diagram with the three distinct points: Maximum payload, maximum fuel and transfer range with no payload.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It plots the maximum achievable range over the aircraft's payload and assumes that the tanks are filled such that the flight starts with the maximum take-off mass. The chart should also have an explanation that clarifies which altitude and which thrust setting were used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or you use approximations like &lt;a href=&quot;https://aviation.stackexchange.com/questions/8652/how-can-i-calculate-the-fuel-consumption-of-an-airbus-320-200-at-various-loads/8654#8654&quot;&gt;Breguet's range equation&lt;/a&gt;, which require detailed knowledge of the aircrafts L/D and the engine's fuel consumption. That will be the weakest point of any range calculation: Sufficient data how changes in the aforementioned parameters affect the result.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-06-06T16:14:44.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15498" PostTypeId="2" ParentId="15495" CreationDate="2015-06-06T16:21:13.240" Score="6" Body="&lt;p&gt;Military aircraft often are painted for camouflage effects.  Aircraft that fly night missions may be entirely black.  The top portions may be painted to make them more difficult to identify from the air while parked on the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different forces and missions have radically different priorities for the appearance of the craft.  Even though you can't make them invisible, simply increasing the time it takes to get a good visual identification can be an advantage for a military craft.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-06-06T16:21:13.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15499" PostTypeId="2" ParentId="8089" CreationDate="2015-06-06T17:37:08.107" Score="3" Body="&lt;p&gt;To decide whether the D-27 really is a propfan, one has to know the mass flow rates through the propeller and through the engine core. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The German wikipedia entry on the turboprop engine &lt;a href=&quot;https://de.wikipedia.org/wiki/Turboprop#Propfantriebwerke&quot; rel=&quot;nofollow&quot;&gt;wikipedia.de/Turboprop&lt;/a&gt; gives the engines bypass-ratio BPR as the criterion for deciding on the engine type:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BPR ~=   9:1 Turbofan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BPR ~=  20:1 Propfan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BPR ~= 100:1 Turboprop &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bypass-ratio is defined as the mass flow rate through fan/prop divided by mass flow rate through engine core.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-06-06T17:37:08.107" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15500" PostTypeId="2" ParentId="3608" CreationDate="2015-06-06T17:42:39.113" Score="9" Body="&lt;p&gt;The preference of an expert for safety-critical systems I listened to once was&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ada&lt;/li&gt;&#xA;&lt;li&gt;C with a programming standard (like Misra-C in the automotive industry).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;He definitely preferred Ada to C. &lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-06-06T17:42:39.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15501" PostTypeId="2" ParentId="15495" CreationDate="2015-06-06T18:34:26.540" Score="36" Body="&lt;p&gt;This &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_camouflage&quot; rel=&quot;nofollow noreferrer&quot;&gt;wiki article&lt;/a&gt; speaks to this somewhat. In modern-day air forces, the paint job will depend on the mission the aircraft is used for. However, with the improvement of radar, visual camouflage is less important than it used to be.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Blacked-out aircraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1hqKIm.jpg&quot; alt=&quot;The F-117 Nighthawk&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft are paint black or nearly black for use in night missions. The F-117 (shown above) was painted with a radar-absorbent paint and also primarily flew at night, lessening its probability of detection. Other aircraft, like the special operations &lt;a href=&quot;http://upload.wikimedia.org/wikipedia/commons/3/3c/MC-130_Combat_Talon_II.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;MC-130&lt;/a&gt; and &lt;a href=&quot;http://www.spectre-association.org/aircraft/ac130_55-0040.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC-130&lt;/a&gt; are painted very dark grays or blacks to lessen their probability of detection since they are primarily used at night in support of covert missions, often at low level where visual detection is the main threat. &lt;em&gt;Modern Examples&lt;/em&gt;: &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-2&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_MC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;MC-130&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Ground camoflauge&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jUMVim.jpg&quot; alt=&quot;Panavia Tornado&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft are painted to blend in to the ground. Some of these are those designed for low-level attack roles (like the Tornado pictured above), to limit the chance of visual detection by enemy fighters from above since their radar signature is unlikely to be detected so low to the ground. Others, like the now-retired &lt;a href=&quot;http://en.wikipedia.org/wiki/Saab_37_Viggen&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 37 Viggen&lt;/a&gt;, may be camouflaged to prevent detection when parked on the ground, as many were dispersed around Sweden, sometimes hidden in forests, to prevent single attacks from taking out many defenses. Many military helicopters are also painted either a patterned or dark green color to blend into forests. Some aircraft have been painted tan to blend into desert environments. &lt;em&gt;Modern Examples&lt;/em&gt;: &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-25&quot; rel=&quot;nofollow noreferrer&quot;&gt;Su-25&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Embraer_EMB_314_Super_Tucano&quot; rel=&quot;nofollow noreferrer&quot;&gt;Super Tucano&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Air camouflage&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wf2k0m.jpg&quot; alt=&quot;Eurofighter Typhoon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many air superiority fighters, and a large group of combat aircraft in general are painted in some way to blend into the sky. I have read that the human eye has difficulty picking a gray plane out against the blue sky (or grayish clouds), and most USAF and NATO planes are painted in some form of &quot;Air Superiority Gray&quot;. Additionally, many will have different-colored tops and bottoms to help blend in from above &lt;em&gt;and&lt;/em&gt; below. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2078/what-is-the-dark-spot-visible-below-the-cockpit-on-a-10s&quot;&gt;This excellent aviation.se Q&amp;amp;A&lt;/a&gt; talks about false cockpits on military jets that contribute to better dogfighting performance. Some aircraft, like the &lt;a href=&quot;http://en.wikipedia.org/wiki/Sukhoi_Su-27&quot; rel=&quot;nofollow noreferrer&quot;&gt;Su-27&lt;/a&gt;, may have several different grays and whites painted on it to break the aircraft's shape up. &lt;em&gt;Modern examples&lt;/em&gt;: &lt;a href=&quot;http://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22&lt;/a&gt;, &lt;a href=&quot;http://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot; rel=&quot;nofollow noreferrer&quot;&gt;MIG-29&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other aircraft that have unique paint jobs to assist in a specialized mission - a darker color on one area to help with sensors, special coatings to minimize damage from a nuclear flash. Overall, it is not as common as it used to be for aircraft to be green - most US Military aircraft were green in color during the Vietnam War, but as the distance of aerial combat has increased, so have the camouflage schemes. Grays are probably the most common paint jobs now among military aircraft of many countries, with other aircraft having specialized paint jobs for specialized roles.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-06T18:34:26.540" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15502" PostTypeId="1" AcceptedAnswerId="15505" CreationDate="2015-06-06T20:37:49.300" Score="6" ViewCount="2177" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/15497/5517&quot;&gt;this answer&lt;/a&gt; to another question, it was stated that: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Take-off mass: If you take no payload, the aircraft will produce less induced drag and reach a slightly higher range&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does a change of weight inside the same shaped container increase induced drag, since the air doesn't come in contact with the cargo?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2018-11-11T00:57:02.390" Title="How does take off mass impact induced drag?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;drag&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15503" PostTypeId="2" ParentId="14901" CreationDate="2015-06-06T20:38:42.843" Score="2" Body="&lt;p&gt;MTOW is defined and then verified by the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During &quot;verification&quot;, tests and other analyses are conducted to show compliance to all MTOW related requirements. For example, landing gear analyses and tests are conducted for their corresponding FAR23 or FAR25 regulations. Flight Loads analyses/tests are also conducted, so that the structure can withstand all foreseeable loads during the entire operational life of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the development of the aircraft, the MTOW can be updated (which is painful and costly) and during flight tests, final tuning can be required. Inceasing MTOW is more costly, in terms of development efforts and re-engineering of the aircraft. Decreasing MTOW would probably limit the operational capacity of the aircraft(less fuel, or less payload).&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-06T20:38:42.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15504" PostTypeId="2" ParentId="15502" CreationDate="2015-06-06T20:47:11.623" Score="3" Body="&lt;p&gt;Induced drag is caused by lift. (historically, Induced Drag was named &quot;lift induced drag&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If weight(mass) of the aircraft decreases, the lift required to fly the aircraft decreases. And the drag associated to that lift also decreases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quoted statement is true, but &quot;slightly&quot; can be discussed. Because the increase in range depends a lot on how much payload the aircraft could carry. (If it's %50 of the max takeoff weight, the range could increase a lot).&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-06T20:47:11.623" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15505" PostTypeId="2" ParentId="15502" CreationDate="2015-06-06T21:51:29.937" Score="3" Body="&lt;p&gt;For the same aircraft speed and an horizontal trajectory:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the aircraft is lighter, less lift is required.&lt;/li&gt;&#xA;&lt;li&gt;To decrease the lift, the angle of attack needs to be reduced (said otherwise: the aircraft flies more horizontal).&lt;/li&gt;&#xA;&lt;li&gt;A smaller AoA creates less induced drag.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Lift and drag coefficients as a function of the angle of attack are represented in the following diagram.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2hkQA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2hkQA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://claesjohnson.blogspot.fr/2012_11_01_archive.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ratio &lt;em&gt;L/D&lt;/em&gt; is also represented, with its maximum &lt;em&gt;L/D max&lt;/em&gt;. &lt;em&gt;L/D max&lt;/em&gt; is an economical angle of attack. After &lt;em&gt;L/D max&lt;/em&gt;, a gain in lift is at the expense of a larger increase in induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side-effect of reduced drag:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The thrust can be reduced to achieve the previous speed.&lt;/li&gt;&#xA;&lt;li&gt;The range is increased thanks to the thrust reduction.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For a more accurate representation of lift and drag coefficients against the angle of attack, and additional information: &lt;a href=&quot;http://www.lets-go-fly.com/Lift%20and%20Drag%20curves%20for%20the%20Wing.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lift and drag curves for the wing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-14T09:34:41.437" LastActivityDate="2016-03-14T09:34:41.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15506" PostTypeId="1" CreationDate="2015-06-06T22:35:51.187" Score="13" ViewCount="4356" Body="&lt;p&gt;On many older aircraft, and in vintage aircraft photos, you can often see long wire antennas strung from some point on the top of the fuselage to the top front of the vertical fin. On newer aircraft, it's either a rare find or not seen at all. The fact that some aircraft even today still have them leads me to wonder about their function - which radio frequency bands they are used for, whether those bands are no longer used, or whether the frequencies are still in use but the long wire has been superseded for most installations by a more compact antenna design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing that modern aviation radio operates in the 108-137 MHz band, and that most modern aircraft use much shorter rigid antennas, the long wire would seem to be inappropriate or unnecessary for that purpose. So, why would aircraft of a more modern design still be equipped with one? What other radio communication (presumably much lower frequency) would call for such an antenna?&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2017-02-20T23:28:42.860" Title="What radio frequency bands are associated with the long wire antennas, why do some aircraft have them and others don't?" Tags="&lt;radio&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15507" PostTypeId="1" AcceptedAnswerId="15509" CreationDate="2015-06-07T00:18:05.063" Score="8" ViewCount="3049" Body="&lt;p&gt;I am proposing a plane that has 2 short wings of the same size on either side of the fuselage (two in the front and two in the back). Rather than using the horizontal stabilizer to destroy lift, the wings in the back help create lift and adjust the pitch of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One problem that I thought of is the wingtip vortex created by the front wing hitting the back wings. I'm guessing this can be resolved by placing the back wings higher than the front wings (from a front view of the fuselage).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could this work?&lt;/p&gt;&#xA;" OwnerUserId="8021" LastEditorUserId="7670" LastEditDate="2015-06-07T03:46:04.957" LastActivityDate="2016-09-03T20:00:34.767" Title="Can a plane with 2 sets of shorter wings fly?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15508" PostTypeId="2" ParentId="15507" CreationDate="2015-06-07T00:44:52.453" Score="9" Body="&lt;p&gt;It would be able to &quot;work&quot;.   Anything with a strong enough engine pointed in the right direction can fly :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is how well it will work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A significant issue is that the most of the problems with wings occur where they join to the fuse, and where they end.   It's the middle part of the wing that works optimally.   So if you half the length of your wings and double the number of them you are giving yourself massively increased end effects...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in comments, the dynamics of stability are also more challenging when you have two main wings producing lift.&lt;/p&gt;&#xA;" OwnerUserId="945" LastEditorUserId="945" LastEditDate="2015-06-07T06:07:32.547" LastActivityDate="2015-06-07T06:07:32.547" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15509" PostTypeId="2" ParentId="15507" CreationDate="2015-06-07T01:52:35.617" Score="16" Body="&lt;p&gt;What you are proposing is called a &quot;tandem wing&quot;, and it's been done before. A brief search should produce more than enough research papers about the advantages and disadvantages of this particular design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The near-complete absence of multiple-wing designs in modern aviation should be a hint that the design has issues. Unless you particularly need the advantages of the design more than the drawbacks, there's no particular reason to use it.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-07T01:52:35.617" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15510" PostTypeId="1" AcceptedAnswerId="15511" CreationDate="2015-06-07T02:11:39.757" Score="26" ViewCount="21157" Body="&lt;p&gt;I'll try to make as much sense as I can with this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been flying quite often in 2015, and I have recently wondered this question regarding high-bypass turbofan engines. I know that there are two primary parts to the high-bypass turbofan: the fans themselves that pull air from the front of the aircraft through the engine, and the fraction of that air that gets compressed and undergoes combustion inside the combustion chamber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given those two main parts that I know about (or so I think I know about), which provides the greatest amount of thrust for the aircraft, the suction and escape of non-combusted air out of the back, or the hot combusted air that is ejected out of the back of the engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for reading, and I hope this question makes sense.&lt;/p&gt;&#xA;" OwnerUserId="8779" LastEditorUserId="14897" LastEditDate="2018-05-16T19:44:14.597" LastActivityDate="2018-09-04T15:25:44.160" Title="What provides the greatest thrust in a high-bypass turbofan engine?" Tags="&lt;turbofan&gt;&lt;thrust&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15511" PostTypeId="2" ParentId="15510" CreationDate="2015-06-07T04:20:23.363" Score="33" Body="&lt;p&gt;I analyzed a &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F100&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney F100 turbofan&lt;/a&gt; last semester in my aerothermodynamics course, so allow me to answer this question. The short answer: &lt;strong&gt;the un-compressed air provides the majority of an engine's total thrust&lt;/strong&gt; since the compressed air powers the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Correction&lt;/strong&gt;: I forgot to mention that the fans also compress entering air. That is, all air entering an engine is compressed a bit by the fan. Some of this compressed air enters the turbojet core and the rest of the fan-compressed air bypasses the engine core. I ignored this for the sake of simplicity, but I should have explained this since you directly asked about air compression in a turbofan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: see below!&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Y7wB2.png&quot; alt=&quot;Turbofan diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1. The fan(s)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air enters the engine through a fan (or fans in the case of the F100 engine). These are the giant fans with a spinning insignia in the middle that you see inside an engine.&lt;img src=&quot;https://i.stack.imgur.com/JtPz1.jpg&quot; alt=&quot;typical jet engine&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update: The spinning insignia clearly show if the fan is spinning so workers don't get injured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fan(s) increases the pressure of the air that enters an engine. Some of this compressed air is diverted around the rest of the engine and is directed straight out of the engine. &lt;strong&gt;The bypass ratio is a measure of how much air bypasses the &quot;jet&quot; core&lt;/strong&gt; (bypass air/core air).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. The compressors&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest of this air is then compressed through a combination of more fans and a converging duct. The data from my thermo project tells me that this stage increases the pressure of the core air by more than 10,000%, but I'm not too sure about that*. Sufficed to say, &lt;strong&gt;this core air now has a lot of energy&lt;/strong&gt;--let's add some more :D&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quick note: The compressed air now has insignificant velocity &lt;em&gt;relative to the bypass air&lt;/em&gt;. Most of the compressed air's energy is &quot;in&quot; its pressure (senior SE members, please correct me if I'm wrong).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. The combustion chamber&lt;/strong&gt; (aka, combustor aka magic chamber)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the core air enters the combustion chamber. Here the air enters small chambers, mixes with jet fuel, and is ignited. The main parts-of-an-engine diagram I posted makes it seam like the combustion chamber is one big part of a jet-engine, but really the combustor consists of a bunch of smaller chambers surrounded the main shaft of the engine. Here is a gif that shows what I mean:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ttgnh.gif&quot; alt=&quot;combustion gif&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How the combustion chamber operates is beyond my scope of understanding, but consider that a combustor is essentially trying to keep a candle alight in the middle of a hurricane. Awesome engineering goes into designing better and more efficient (hotter-burning) chambers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4. The turbine&lt;/strong&gt; (aka more magic section)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that hot and even more energetic air enters a the turbine section which consists of a diverging (increasing in area) duct and more fans. Whereas the compress &quot;inserted&quot; energy into the air, the turbines draw out energy from the air. As the air enters the larger (in volume) turbine area, it expands and spins the turbine fans &lt;strong&gt;which power the compressors and the fan&lt;/strong&gt;. This Back Work Ratio (BWR) is a measure of how much turbine power it takes to spin the compressors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;5. The nozzle&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The still energetic core air is once again concentrated before being shot out of the back of the engine.This thrust, together with the thrust of the bypass air, propels the air forward following this model:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F_{thrust} = \dot{m}_{bypass} \times \Delta v_{bypass} + \dot{m}_{core} \times \Delta v_{core}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $\dot{m}_{bypass}$ is the mass flow-rate of air that is bypassed and $\Delta v_{bypass}$ is the change in velocity of that air as a result of the fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And $\dot{m}_{core}$ is the mass flow-rate of air that is combusted and $\Delta v_{core}$ is the change in velocity of the core air as a result of the fan, compressor, combustion chamber, and turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The uncompressed air contributes about 60% of the total thrust.&lt;/strong&gt; The &quot;processed&quot; air loses a significant portion of its energy to powering the engine. However, &lt;em&gt;the compressed air still provides about 40% of the total thrust&lt;/em&gt;. Adding an afterburner can increase this contribution to 50%. How is this possible? Dead algae from a billion years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hydrocarbons in jet fuel pack a lot of energy into a small &lt;a href=&quot;http://en.wikipedia.org/wiki/Energy_density&quot; rel=&quot;noreferrer&quot;&gt;space&lt;/a&gt; &lt;em&gt;and&lt;/em&gt; &lt;a href=&quot;http://en.wikipedia.org/wiki/Specific_energy&quot; rel=&quot;noreferrer&quot;&gt;mass&lt;/a&gt; (two completely different concepts). Burning those hydrocarbons releases a lot of energy that powers the fan, compressors, and electric generators of an aircraft before pushing the airplane forward. This high energy in a small place/space is also why electric cars/anything weren't practical until LiPo batteries (story for another article). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I applaud you for noticing that the uncompressed air contributes to an engine's thrust. I think the term &quot;bypass&quot; confuses some people into thinking that this air is &quot;thrown away&quot;. it's not. The bypassed air is actually sped up by a series of fans and imparts forward momentum to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm studying Aerospace engineering right now (Whoop!), so my excitement at being able to answer this question rather side-tracked me from your original question, but I hope you enjoy the extra info on how a turbofan operates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional info&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hotter a combustion chamber burns, the hotter the core air gets and the more energy it can provide for engine operation. Furthermore, hotter chambers waste less jet fuel and result in relatively cleaner and safer fumes. Increasing CC max temps and designing the rest of the engine (i.e., the turbine blades) to handle the increase in temp is the cutting edge of engine research. This is one of the most challenging and lucrative materials science/engineering problems in the world since efficiency is paramount in today and tomorrow's aviation industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.economist.com/node/21553017&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; is a nice article describing how GE, Rolls-Royce, and other engine companies sell thrust, not engines. It's a big long, so you may  read it on your next flight :)&lt;/p&gt;&#xA;" OwnerUserId="4432" LastEditorUserId="14897" LastEditDate="2017-03-04T20:42:25.783" LastActivityDate="2017-03-04T20:42:25.783" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15514" PostTypeId="2" ParentId="15506" CreationDate="2015-06-07T15:38:48.620" Score="7" Body="&lt;p&gt;The &quot;long wire&quot; antenna is an HF antenna, and operates in the 2 to 30 Mhz band.&#xA;Not all aircraft will use them, only aircraft that need to communicate further than a VHF radio. Typically these are found on larger aircraft including some larger helicopters.&#xA;The Sea King helicopter uses this antenna as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is still appropriate today as the propagation with the electro magnetic waves in this frequency band is much higher than the VHF band and allows for the aircraft to communicate part way around the world. &lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2015-06-07T15:38:48.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15518" PostTypeId="1" CreationDate="2015-06-07T19:16:12.237" Score="4" ViewCount="5271" Body="&lt;p&gt;When the wing of an aircraft is located above the fuselage, the aircraft is generally considered more stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the wing of an aircraft is located below the majority of the fuselage, the aircraft is generally considered more acrobatic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why then, do large commercial jumbojets generally have their wings located towards the center (from top to bottom) or bottom of the aircraft?  On first glance, this design seems odd since one of their primary goals is stability in flight.&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="19" LastEditDate="2016-07-04T12:21:45.077" LastActivityDate="2016-07-04T12:21:45.077" Title="Why is the wing of large commercial jet aircraft usually located below the fuselage?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;wing&gt;&lt;fixed-wing&gt;&lt;fuselage&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15519" PostTypeId="1" AcceptedAnswerId="27781" CreationDate="2015-06-07T19:41:32.323" Score="4" ViewCount="184" Body="&lt;p&gt;I'm interested in the information about air routes of all the world. I need information with following features:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;it must be official (not stolen, without violating any license);&lt;/li&gt;&#xA;&lt;li&gt;it should be in digital form;&lt;/li&gt;&#xA;&lt;li&gt;it should be in &lt;a href=&quot;https://en.wikipedia.org/wiki/World_Geodetic_System&quot; rel=&quot;nofollow&quot;&gt;WGS84&lt;/a&gt;;&lt;/li&gt;&#xA;&lt;li&gt;it should cover all of the world;&lt;/li&gt;&#xA;&lt;li&gt;it should be free (no payment);&lt;/li&gt;&#xA;&lt;li&gt;it shouldn't be detailed (just main routes);&lt;/li&gt;&#xA;&lt;li&gt;it shouldn't be actual (current), one or two years outdated is appropriate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've realised that some kind of this information is published by &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization&quot; rel=&quot;nofollow&quot;&gt;ICAO&lt;/a&gt; at the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeronautical_Information_Publication&quot; rel=&quot;nofollow&quot;&gt;AIP&lt;/a&gt;, but I can't find it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: whether such information is available and where I can find it?&lt;/p&gt;&#xA;" OwnerUserId="2575" LastEditorUserId="8482" LastEditDate="2015-06-08T05:43:31.863" LastActivityDate="2016-05-25T05:05:41.087" Title="Does official source of data about air routes exists?" Tags="&lt;icao&gt;&lt;flight-path&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15520" PostTypeId="1" CreationDate="2015-06-07T21:26:26.340" Score="2" ViewCount="9686" Body="&lt;p&gt;Does someone know anything about APU bleed air supply in this pic?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/cUgkn.jpg&quot; alt=&quot;air conditioning system&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8668" LastActivityDate="2015-06-08T00:47:00.373" Title="why there is APU bleed air supply?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15521" PostTypeId="2" ParentId="15520" CreationDate="2015-06-07T21:33:48.797" Score="3" Body="&lt;p&gt;APU is there for the bleed (and running some electrics).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using that bleed an aircraft at the gate (with engines shut off for ground personnel safety reasons) can run the airconditioning and start the engines without needing pressurized air supplied from the ground from a huffer cart.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-06-07T21:33:48.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15522" PostTypeId="2" ParentId="15389" CreationDate="2015-06-07T21:54:13.343" Score="6" Body="&lt;p&gt;Although not exactly the same thing you're asking you might be able to surmise an answer about Airbus from what happened in the crash of TAM flight 3054. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was an A320 landing in Sao Paulo with a known inop T/R on the right engine. The pilots retarded the left thrust lever to idle to engage spoilers and then into reverse to engage left T/R but left the right lever in CLIMB. The autothrust turned off and due to the lever positions the left engine went into reverse thrust while the right engine went into full forward thrust causing them to veer off and overrun the runway and crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Airbus this had been a problem before so they changed the procedure for single T/R. It was previously to bring both to idle then only the working one to reverse. This was apparently confusing the pilots causing accidents so they changed it. The correct procedure is now to bring BOTH levers to idle then at touchdown, BOTH to reverse. Obviously if this is the procedure the A320 will not normally spool up the engine that did not have reverse thrust. The only reason it did was because the pilot left the right lever in the climb detent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if this is true if the T/R's were PREVENTED from deploying due to the wheels not touching down but I would figure it would. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way the A320 thrust levers work is that you release a catch then pull the levers aftward past the idle detent. (Not a pilot so correct me if I'm wrong here) Other a/c have a separate set of levers, for reverse thrust, sometimes hinged to the main thrust levers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this illustration I found at &lt;a href=&quot;http://cyberpilot.tripod.com/engine_systems.html&quot; rel=&quot;noreferrer&quot;&gt;this site&lt;/a&gt; the DC10 did have such a system to prevent the thrust to be increased until the reversers were deployed. &lt;img src=&quot;https://i.stack.imgur.com/zj5BH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to a BEA investigation report the B747 has a similar system:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The thrust reverser mechanism is commanded by one lever located on each thrust lever. In the ground position and when the thrust levers are at idle, it is possible to pull the thrust reverser levers back to the &quot;interlock&quot; position which corresponds to reverse. This unlocks the reversers and initiates their deployment. There is blocking in the interlock position when the reversers are in motion or incompletely extended. The use of full reverse thrust is possible when the &quot;in transit&quot; lights are off and the &quot;unlock&quot; lights are on (see appendix 2) to indicate that the reversers are deployed and locked. (&lt;a href=&quot;http://www.bea.aero/docspa/2000/tj-b001105a/htm/tj-b001105a.htm&quot; rel=&quot;noreferrer&quot;&gt;BEA site&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-06-07T21:54:13.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15523" PostTypeId="5" CreationDate="2015-06-07T23:03:53.767" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-07T23:03:53.767" LastActivityDate="2015-06-07T23:03:53.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15524" PostTypeId="4" CreationDate="2015-06-07T23:03:53.767" Score="0" Body="The airbus-neo (New Engine Option) aircraft are a set of aircraft in development by airbus that is designed to be more efficient." OwnerUserId="7670" LastEditorUserId="7670" LastEditDate="2015-06-08T01:26:07.830" LastActivityDate="2015-06-08T01:26:07.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15525" PostTypeId="2" ParentId="15389" CreationDate="2015-06-08T00:00:02.180" Score="2" Body="&lt;p&gt;For the regulatory aspects of this question.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§ 25.933 Reversing systems.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) For turbojet reversing systems—&lt;/p&gt;&#xA;&lt;p&gt;(1) Each system intended for ground operation only must be designed so that during any reversal in flight the engine will produce no more than flight idle thrust. In addition, it must be shown by analysis or test, or both, that—&lt;/p&gt;&#xA;&lt;p&gt;(i) Each operable reverser can be restored to the forward thrust position; and&lt;/p&gt;&#xA;&lt;p&gt;(ii) The airplane is capable of continued safe flight and landing under any possible position of the thrust reverser.&lt;/p&gt;&#xA;&lt;p&gt;(2) Each system intended for inflight use must be designed so that no unsafe condition will result during normal operation of the system, or from any failure (or reasonably likely combination of failures) of the reversing system, under any anticipated condition of operation of the airplane including ground operation. Failure of structural elements need not be considered if the probability of this kind of failure is extremely remote.&lt;/p&gt;&#xA;&lt;p&gt;(3) Each system must have means to prevent the engine from producing more than idle thrust when the reversing system malfunctions, except that it may produce any greater forward thrust that is shown to allow directional control to be maintained, with aerodynamic means alone, under the most critical reversing condition expected in operation.&lt;/p&gt;&#xA;&lt;p&gt;(b) For propeller reversing systems—&lt;/p&gt;&#xA;&lt;p&gt;(1) Each system intended for ground operation only must be designed so that no single failure (or reasonably likely combination of failures) or malfunction of the system will result in unwanted reverse thrust under any expected operating condition. Failure of structural elements need not be considered if this kind of failure is extremely remote.&lt;/p&gt;&#xA;&lt;p&gt;(2) Compliance with this section may be shown by failure analysis or testing, or both, for propeller systems that allow propeller blades to move from the flight low-pitch position to a position that is substantially less than that at the normal flight low-pitch position. The analysis may include or be supported by the analysis made to show compliance with the requirements of § 35.21 of this chapter for the propeller and associated installation components.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-08T00:00:02.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15526" PostTypeId="2" ParentId="15520" CreationDate="2015-06-08T00:47:00.373" Score="6" Body="&lt;p&gt;The APU is an alternate source of electrical power and also bleed air.  Since it doesn't have any function to generate thrust, it burns considerably less fuel than the engines do, and is intended primarily for ground use, although most APU's can also be operated in flight for things like a second source of electrical power if an engine generator has failed, or a source of bleed air if the bleeds are closed on the engines in order to generate more thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that diagram, what you're seeing is a portion of the pneumatic system, showing that the bleed air from the APU can be routed to both air conditioning packs (on many aircraft the APU can power both AC packs on the ground; on some aircraft it can only power one at a time), as well as to the engines, where it provides air for starting them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On some aircraft, the bleed air from the APU can do other things, like pressurizing the water supply, and while it isn't operationally useful, it can generally supply bleed air into the anti-ice ducting for the leading edges.  In practice, though, that's only done when the engines are running, due to the greater volume (and temperature) of hot bleed air that the engines can produce compared to the APU.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-08T00:47:00.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15527" PostTypeId="1" AcceptedAnswerId="15536" CreationDate="2015-06-08T00:54:33.413" Score="6" ViewCount="309" Body="&lt;p&gt;How does the aviation industry (pilots and ATC in particular, as opposed to cabin crew) train and certify English proficiency? Do they use classes and examinations associated with general-purpose English training, or ones specifically associated with the aviation industry?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I heard several years ago from Air Crash Investigation that a contributing factor for the &lt;a href=&quot;http://en.wikipedia.org/wiki/Avianca_Flight_52&quot; rel=&quot;nofollow&quot;&gt;Avianca Flight 52&lt;/a&gt; crash was the use of the wrong terminology in communication between the non-native speaking pilots and the ATC.&lt;/p&gt;&#xA;" OwnerUserId="2250" LastEditorUserId="65" LastEditDate="2015-06-08T15:45:56.773" LastActivityDate="2015-06-08T16:43:50.030" Title="How does the aviation industry train and certify English proficiency?" Tags="&lt;flight-training&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15528" PostTypeId="2" ParentId="15527" CreationDate="2015-06-08T01:48:29.300" Score="3" Body="&lt;p&gt;There exists specialised &quot;Aviation English&quot; training for non-native speakers. In such courses, they teach not only basic English proficiency, plus a large amount of technical aviation-specific language (both common and mandated by ICAO standard procedures).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is one organisation that offers such courses: &lt;a href=&quot;http://www.airways.co.nz/airways_international/aviation-english.asp&quot; rel=&quot;nofollow&quot;&gt;Airways Aviation English Training&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-06-08T01:48:29.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15529" PostTypeId="1" AcceptedAnswerId="16404" CreationDate="2015-06-08T03:37:51.750" Score="1" ViewCount="848" Body="&lt;p&gt;Data Transformation Corporation issued the &lt;a href=&quot;https://www.duat.com/news_item.html?item=18&quot; rel=&quot;nofollow&quot;&gt;press release&lt;/a&gt; below.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FOR IMMEDIATE RELEASE&lt;/p&gt;&#xA;  &#xA;  &lt;h3&gt;DTC DUAT Contract Extension&lt;/h3&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;May 21, 2015&lt;/strong&gt; — Data Transformation Corporation, DTC DUAT which&#xA;  supplies the DUAT Service for the FAA for the past 25 years, has&#xA;  announced that it has been granted a 60 day extension by the FAA to&#xA;  continue to provide the FAA DUAT service. DTC DUAT has always been&#xA;  committed to making the DUAT Service better for General Aviation&#xA;  pilots by adding new features and services making it easier to get&#xA;  weather briefings and file flight plans. DTC would like to inform all&#xA;  of its users and third party vendors that we are fully operational and&#xA;  plan to continue operations during and after the 60 day period. DTC&#xA;  DUAT is pursuing alternative avenues to provide the DUAT Service&#xA;  capabilities to its users following the 60 day extension period.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For more information on this topic or anything about DUAT, please&#xA;  contact our marketing manager, Doug Priestley, at (800) FAA-DUAT&#xA;  (322-3828) or by email at&#xA;  marketing@dtcduat.com.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the alternative avenues do not produce the desired results and DTC DUAT operations cease, what will be the real-world, day-to-day effects on general aviation?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="62" LastEditDate="2015-06-29T18:23:29.087" LastActivityDate="2015-07-25T18:25:37.777" Title="What will the impact to GA be if DTC DUAT goes away?" Tags="&lt;general-aviation&gt;&lt;flight-planning&gt;&lt;usa&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15530" PostTypeId="2" ParentId="15518" CreationDate="2015-06-08T04:10:55.767" Score="1" Body="&lt;p&gt;There are regulations regarding&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Pitch Rate&lt;/li&gt;&#xA;&lt;li&gt;Roll Rate&lt;/li&gt;&#xA;&lt;li&gt;Yaw Rate&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;Out of this, the regulations regarding roll rate are as under:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h1&gt;§23.157 Rate of roll.&lt;/h1&gt;&#xA;&lt;p&gt;(a) Takeoff. It must be possible, using a favorable combination of controls, to roll the airplane from a steady 30-degree banked turn through an angle of 60 degrees, so as to reverse the direction of the turn within:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;For an airplane of 6,000 pounds or less maximum weight, 5 seconds from initiation of roll; and&lt;/li&gt;&#xA;&lt;li&gt;For an airplane of over 6,000 pounds maximum weight, W+5001,300 seconds, but not more than 10 seconds, where W is the weight in pounds.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;(b) The requirement of paragraph (a) of this section must be met when rolling the airplane in each direction with—&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flaps in the takeoff position;&lt;/li&gt;&#xA;&lt;li&gt;Landing gear retracted;&lt;/li&gt;&#xA;&lt;li&gt;For a single-engine airplane, at maximum takeoff power; and for a multiengine airplane with the critical engine inoperative and the propeller in the minimum drag position, and the other engines at maximum takeoff power; and&lt;/li&gt;&#xA;&lt;li&gt;The airplane trimmed at a speed equal to the greater of 1.2VS1 or 1.1VMC, or as nearly as possible in trim for straight flight.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;(c) Approach. It must be possible, using a favorable combination of controls, to roll the airplane from a steady 30-degree banked turn through an angle of 60 degrees, so as to reverse the direction of the turn within:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;For an airplane of 6,000 pounds or less maximum weight, 4 seconds from initiation of roll; and&lt;/li&gt;&#xA;&lt;li&gt;For an airplane of over 6,000 pounds maximum weight, W+2,8002,200 seconds, but not more than 7 seconds, where W is the weight in pounds.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;(d) The requirement of paragraph (c) of this section must be met when rolling the airplane in each direction in the following conditions—&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flaps in the landing position(s);&lt;/li&gt;&#xA;&lt;li&gt;Landing gear extended;&lt;/li&gt;&#xA;&lt;li&gt;All engines operating at the power for a 3 degree approach; and&lt;/li&gt;&#xA;&lt;li&gt;The airplane trimmed at VREF.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Hence, a too stable plane cannot achieve such rates at the prescribed mach number, and the control surface deflection. So the wing position is kept so as to meet this requirement. Moreover, if you think that such configuration of the wing would make the airplane inherently unstable, the modern computers on the plane with proper feedback systems take care of such a thing.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-08T04:45:54.960" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15532" PostTypeId="2" ParentId="15519" CreationDate="2015-06-08T04:49:34.720" Score="2" Body="&lt;p&gt;I a m not sure about the WGS84 convention requirement, but some websites do provide flight data (which might not be up to date), but is fairly new (2012).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://arm.64hosts.com/&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; to one of the websites which provides data about 669 airlines, 3310 air ports covering about 56749 routes. You can also have a look at &lt;a href=&quot;http://openflights.org/blog/2009/10/13/comprehensive-airline-route-data-released/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://openflights.org/data.html&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-08T04:49:34.720" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15533" PostTypeId="5" CreationDate="2015-06-08T04:58:20.593" Score="0" Body="&lt;p&gt;Questions regarding the shape, structure, identification, working of turbines and compressors, where the shape of the blade attached to the compressor or the turbine is important should be enclosed under this tag.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-08T05:25:48.373" LastActivityDate="2015-06-08T05:25:48.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15534" PostTypeId="4" CreationDate="2015-06-08T04:58:20.593" Score="0" Body="Vane is a  broad blade attached to a rotating axis or wheel which pushes or is pushed by wind or water and forms part of a machine or device such as a windmill, propeller, or turbine." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-08T05:25:37.237" LastActivityDate="2015-06-08T05:25:37.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15535" PostTypeId="2" ParentId="15518" CreationDate="2015-06-08T05:15:37.387" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;When the wing of an aircraft is located above the fuselage, the aircraft is generally considered more stable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;High-wings increase stability in &lt;em&gt;roll&lt;/em&gt;. It does not significantly affect stability in pitch and yaw; for those appropriate tail design is needed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why then, do large commercial jumbojets generally have their wings located towards the center of the aircraft (from top to bottom)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is more efficient.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On first glance, this design seems odd since one of their primary goals is stability in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, it isn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most important is stability in pitch, because pitch is related to speed and energy management. But that just needs appropriate horizontal stabilizer and high or low wing does not matter. Stability in yaw is also important, but that is achieved by appropriate vertical stabilizer, again with little difference between high and low wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in roll, the aircraft &lt;em&gt;must not be stable too much&lt;/em&gt;. High roll stability provokes &lt;a href=&quot;http://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow&quot;&gt;dutch roll&lt;/a&gt; oscillation and reduces manoeuvrability. So aircraft are designed to be only very slightly stable in roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And even for roll stability both low and high wing designs can be relatively easily adjusted for the right amount. Roll stability can be increased by adding &lt;a href=&quot;http://en.wikipedia.org/wiki/Dihedral_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;dihedral&lt;/a&gt; and decreased by adding anhedral as needed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-08T05:15:37.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15536" PostTypeId="2" ParentId="15527" CreationDate="2015-06-08T05:36:55.157" Score="5" Body="&lt;p&gt;Proficiency in English is something very much required in aviation. One other major accident I remember is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Charkhi_Dadri_mid-air_collision&quot; rel=&quot;nofollow noreferrer&quot;&gt;Charkhi Dadri mid-air collision&lt;/a&gt;, which resulted in 349 fatalities, and one of the major reasons was believed to be the poor English of Kazakh Airlines crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keeping such importance of English in mind, and the need to standardize English testing and training, the &lt;a href=&quot;http://www.icao.int&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO&lt;/a&gt;  has issued &lt;a href=&quot;http://www.icao.int/safety/lpr/Documents/323_en.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Guidelines for Aviation English Training Programmes.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Training&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Candidates are trained for Aviation English in a very similar way to it would be for any other purpose, other than ensuring the following points:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Use of operationally relevant, work-related language.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Exposure to an aviation environment. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Practical training activities such as Listening practice in ATC lab.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Testing&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The Test of English For Aviation is a test Developed by &lt;a href=&quot;http://www.maycoll.co.uk/aviation-english/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mayflower College&lt;/a&gt; in accordance with ICAO's ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is how the candidates are tested in TEA:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TEA candidates can score from Level 1 to Level 6 but most candidates score Level 3, 4 or 5. Candidates are awarded a mark from 1 to 6 for each of the 6 skills: pronunciation, structure, vocabulary, fluency, interactions, comprehension. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CnhaJ.png&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.maycoll.co.uk/aviation-english/guide_for_students.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Read this document&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="97" LastEditDate="2015-06-08T16:43:50.030" LastActivityDate="2015-06-08T16:43:50.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15537" PostTypeId="1" CreationDate="2015-06-08T06:06:48.913" Score="14" ViewCount="468" Body="&lt;p&gt;When both propellers of the aircraft reach the time limit (60 month) and need to be replaced, can both propellers be replaced at the same time and perform only one flight test to reduce time on ground or should they be replaced one at a time just for safety or to investigate any discrepancy that may arise?  &lt;/p&gt;&#xA;" OwnerUserId="8789" LastEditorUserId="12720" LastEditDate="2016-01-26T02:40:00.867" LastActivityDate="2016-01-26T14:24:30.850" Title="How to replace two propellers on the same aircraft reaching the time limit?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15538" PostTypeId="2" ParentId="15518" CreationDate="2015-06-08T07:08:20.013" Score="6" Body="&lt;p&gt;First of all, I do not agree with your assessment: The wing of large commercial aircraft is clearly below the fuselage, to allow the cabin not to become &lt;a href=&quot;https://aviation.stackexchange.com/questions/1917/why-do-large-aircraft-have-their-engines-mostly-on-the-wings-while-smaller-ones/7518#7518&quot;&gt;divided by the wing spar&lt;/a&gt;. The A380 would have better aerodynamics if the designers had interrupted the lower cabin by the wing spar, but the airlines did not want this at all. Please look at the picture below: I hope you will agree that the wing is clearly below the majority of the fuselage. Why this is done &lt;a href=&quot;https://aviation.stackexchange.com/questions/6319/why-do-almost-all-military-transports-have-high-wings-and-civilian-transports&quot;&gt;has been answered here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/701/what-are-the-pros-and-cons-of-high-wing-compared-to-low-wing-design&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mlXkN.jpg&quot; alt=&quot;Air France A380 during approach&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large commercial aircraft have low wings to stow away their long landing gears. Long gears make it possible to stretch the fuselage and still be able to rotate during take-off. Large high-wing aircraft with their low fuselage position are easier to load and unload, at the price that the fuselage taper has to start shortly aft of the landing gear, so no stretching is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mid-wing design is common to aerobatic aircraft. For &lt;a href=&quot;https://aviation.stackexchange.com/questions/7560/aerobatic-aircraft-symmetrical-airfoils-and-angle-of-incidence&quot;&gt;ideal roll handling&lt;/a&gt;, all parts should be aligned along a single axis, and doing this complicates fuselage design. Only for aerobatic aircraft the benefits outweigh the disadvantages. See the picture of an Extra 300 below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/R3sH4.jpg&quot; alt=&quot;Patty Wagstaff in her Extra 300 S&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high wing is selected when the gear height should be low for loading and unloading, when the downward field of view of the pilot should not be restricted (think &lt;a href=&quot;https://en.wikipedia.org/wiki/Parasol_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;parasol design&lt;/a&gt; in WW I), when the wing should have more ground clearance during landing (think gliders) or when the wing is meant to &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_AD-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;pivot horizontally&lt;/a&gt; (see picture below for an example). Note that the combination of a high wing and wing sweep will produce too much sideslip stability and needs to be &lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/why-does-an-225-have-anhedral-wings-though-it-is-a-cargo-aircraft&quot;&gt;corrected with anhedral&lt;/a&gt;. All three (sweep, wing position and anhedral) change with angle of attack, and the combination will still have too much or too little stability away from the design angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YtciU.jpg&quot; alt=&quot;NASA AD-1 research aircraft in flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Jan Hudec pointed out, pitch and yaw stability depend mostly on tail size and location, and even roll stability is affected by more than the wing's location. The location is a compromise of many, sometimes diverging parameters, and stability is only a small part of it.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-06-08T09:51:55.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15539" PostTypeId="1" CreationDate="2015-06-08T07:33:19.150" Score="3" ViewCount="3014" Body="&lt;p&gt;Why does ADS-B and geometric height (calculated height) differ from each other? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the geometric heights are calculated at night where the temperature is lower, then the result should be different during the day, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is ADS-B with night or day calculated height smaller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the more accurate result to be referenced?&lt;/p&gt;&#xA;" OwnerUserId="8709" LastEditorUserId="1696" LastEditDate="2016-06-14T17:09:02.197" LastActivityDate="2017-01-17T12:46:54.020" Title="What is the differences of ADS-B and geometric height?" Tags="&lt;air-traffic-control&gt;&lt;avionics&gt;&lt;altitude&gt;&lt;ads-b&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15541" PostTypeId="1" AcceptedAnswerId="15585" CreationDate="2015-06-08T08:07:52.840" Score="1" ViewCount="483" Body="&lt;p&gt;How does the servo control spoiler actuation mechanism on the Airbus A340 work? &lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-28T11:31:34.710" LastActivityDate="2016-07-28T11:31:34.710" Title="How does the spoiler actuation mechanism work on the Airbus A340?" Tags="&lt;airbus&gt;&lt;spoilers&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15542" PostTypeId="2" ParentId="14501" CreationDate="2015-06-08T09:25:42.923" Score="31" Body="&lt;p&gt;&lt;strong&gt;What is this turbine part?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This assembly is part of the turbine used to rotate the compressor section of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney PT6&lt;/a&gt;, a free turbine turboprop. It's known as &lt;em&gt;compressor turbine&lt;/em&gt; or just &lt;em&gt;CT&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Where is it located?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The compressor turbine is located at the exit nozzle of the annular combustion chamber, and is the first component which enters in rotation under the effect of the hot gas velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pOsfL.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pOsfL.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Compressor turbine. Source: &lt;a href=&quot;https://www.scribd.com/document/149012327/PT6T-Engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;P&amp;amp;W Training Manual&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As visible, there is a second turbine (made of one or more stages, depending on the PT6 model) further downstream. They appear to be on the same shaft, but they aren't. There are two independent shafts rotating at their own angular speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The compressor turbine extracts power to rotate mostly the engine compressor, which role is to feed the combustion chamber with compressed air. The other turbine extracts power used (mostly) for the aircraft propulsion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is looks like on the real thing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wfgSv.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wfgSv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://youtu.be/hQri0heCepA?t=92&quot; rel=&quot;nofollow noreferrer&quot;&gt;AVweb&lt;/a&gt; on Youtube&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two shafts can be seen on the picture above, separated by the interstage baffle within the power turbine vane ring assembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turbine blades material&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qk6gq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qk6gq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://www.instazu.com/media/2089887755836751776&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades, the hottest parts after the combustion chamber, are made of a nickel alloys. Nickel itself melts at 1,455 °C, and alloys are made more resistant either by solidified directional casting or single crystal growth (see &lt;a href=&quot;https://aviation.stackexchange.com/q/25645/3201&quot;&gt;more on materials&lt;/a&gt;). In larger engines turbine blades are often maintained below their melting point by &lt;a href=&quot;https://aviation.stackexchange.com/q/34378/3201&quot;&gt;circulating air in small internal channels&lt;/a&gt;. This is not the case for the PT6, gas temperature is still below the melting point (about 900°C).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blades are protected by an anti-corrosion coating to delay as much as possible the inclusion of ion-sulfur into a material, a reaction known as &lt;a href=&quot;https://www.euravia.aero/news/what-is-sulphidation&quot; rel=&quot;nofollow noreferrer&quot;&gt;sulphidation&lt;/a&gt;. Nickel sulphidation forms &lt;span class=&quot;math-container&quot;&gt;$\small Ni_3 S_2$&lt;/span&gt; which melts at 635 °C. Sulphidation occurs all the time, but more quickly when flying close to sea water or industrial areas rich in sodium salts which can form sodium sulfate (more &lt;a href=&quot;https://www.jim.or.jp/journal/e/pdf3/29/01/26.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;). Frequent water washes of the turbine maybe necessary to eliminate salts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking online for &lt;a href=&quot;https://www.google.com/search?complete=0&amp;amp;q=pt6%20sulphidation%20investigation&quot; rel=&quot;nofollow noreferrer&quot;&gt;PT6 sulphidation&lt;/a&gt;, we can see a large number of investigation reports dealing with engine failures due to maintenance not done according to procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;About the P&amp;amp;W PT6 engine&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PT6 is a well known engine, available in &lt;a href=&quot;http://all-aero.com/index.php/contactus/64-engines-power/13099-pratt-whitney-canada-pt6&quot; rel=&quot;nofollow noreferrer&quot;&gt;various versions&lt;/a&gt;, which has been used for 50 years on aircraft and helicopters (&lt;a href=&quot;http://blog.covingtonaircraft.com/2014/05/20/surprising-past-pt6/&quot; rel=&quot;nofollow noreferrer&quot;&gt;but also&lt;/a&gt; on IndyCars, hovercraft, &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/UAC_TurboTrain&quot; rel=&quot;nofollow noreferrer&quot;&gt;turbotrain&lt;/a&gt;&quot;, snowplows....).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WVDly.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.primeturbines.com/pt6a-hot-section-inspection.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The particularity is the free turbine design. On large turbo-engines, the compressor (the low pressure compressor on engines with two or three spools) is on the same shaft than the engine output (which drives the fan, the rotor, the speed reduction gear,etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a free turbine there are two rotating groups that are not linked by a shaft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C3JZT.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C3JZT.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://ubibliorum.ubi.pt/bitstream/10400.6/3445/1/2015_Disserta%C3%A7%C3%A3o_DiogoGuimar%C3%A3es.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The first group is the &lt;em&gt;gas generator section&lt;/em&gt; -- in blue, on the right hand of the images -- with a compressor and a combustion chamber. High pressure gas are sent to the last stage of the gas generator, which is a turbine stage -- the compressor turbine or CT, the one you've got. The CT drives the whole gas generator section and the accessory gearbox.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The energy used to move the generator section is only a part of the available energy in the hot gas (e.g. 66% on a twin PT6T-3D). The rest makes it's way to the mechanically-independent &lt;em&gt;power section&lt;/em&gt; composed of one or more turbines, depending on the engine model. The turbines drive either the propeller, the rotor, or anything attached to the power section shaft, directly or via a reduction gearbox.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The gas production section can be spun (albeit at idle) wit the power section at rest (an helicopter turbine can be spun, while the rotor is maintained stationary).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-08T16:04:06.133" LastActivityDate="2019-11-08T16:04:06.133" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="15543" PostTypeId="2" ParentId="15539" CreationDate="2015-06-08T09:40:49.267" Score="7" Body="&lt;p&gt;ADS-B, and the older Transponder Mode C, report &lt;a href=&quot;http://en.wikipedia.org/wiki/Pressure_altitude&quot; rel=&quot;nofollow&quot;&gt;pressure altitude&lt;/a&gt;. That is static pressure where the plane is expressed as altitude at which that pressure occurs in &lt;a href=&quot;http://en.wikipedia.org/wiki/International_Standard_Atmosphere&quot; rel=&quot;nofollow&quot;&gt;international standard atmosphere&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In low pressure area, the same pressure density corresponds occurs at lower geometric altitude with similar difference at all altitudes. In higher temperature, the air is denser and the isobars closer together, so the same pressure altitude occurs at lower geometric altitude and the difference increases with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However for purpose of traffic separation, pressure altitude is always used. Due to physical properties of air, the pressure always decreases with altitude and at the same altitude changes only slowly with position, so we can always rely on close aircraft observing sufficiently different pressure altitude being at sufficiently different geometrical altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is that while barometric altimeter is simple, accurate to less than 100 ft and every aircraft has it since the early days of aviation, there was &lt;em&gt;no&lt;/em&gt; way to measure geometric altitude before selective availability was turned off in GPS in 2000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Geometrical altitude is altitude above the reference geoid (usually WGS84), a.k.a the sea level. It is only used internally in &lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_proximity_warning_system&quot; rel=&quot;nofollow&quot;&gt;EGPWS&lt;/a&gt; where it is provided by GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast height is in aviation always used to mean height above terrain. It may be measured directly using &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;nofollow&quot;&gt;radar altimeter&lt;/a&gt; or it can be estimated from pressure altitude by correcting for sea-level pressure at the nearest airfield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar altitude is used in GPWS as a backup datum and in older such systems  from before GPS was available (those systems could warn if you were too low, but not if you were approaching high ground, because the radar altimeter only measures down while the new GPS-based systems have a terrain map and compare the GPS position with it) and is shown to pilot for reference, but it is not broadcast anywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approaches are normally flown in reference to the barometric altitude that is corrected for pressure at airport (the altimeter has setting for reference sea-level pressure, QNH), but not temperature. So the barometric altimeter shows true altitude at the airport, but when it's cold, it shows more than true altitude above. That's why some approaches have minimum temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, both Mode C and ADS-B broadcast pressure altitude, i.e. as calculated for standard pressure of 29.92 inHg/1013 hPa.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-09T04:58:30.260" LastActivityDate="2015-06-09T04:58:30.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15545" PostTypeId="1" AcceptedAnswerId="15549" CreationDate="2015-06-08T10:23:57.900" Score="22" ViewCount="4679" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/IndiGo&quot; rel=&quot;nofollow&quot;&gt;Indigo&lt;/a&gt; is a low cost carrier, which already has 99 A-320s in its fleet has  &lt;a href=&quot;http://timesofindia.indiatimes.com/business/india-business/In-record-deal-IndiGo-Airlines-buys-250-planes-for-25-5-billion/articleshow/44830539.cms&quot; rel=&quot;nofollow&quot;&gt;ordered&lt;/a&gt; 431 more. This airline currently covers 35 routes, while the full service carrier &lt;a href=&quot;http://en.wikipedia.org/wiki/Emirates_(airline)&quot; rel=&quot;nofollow&quot;&gt;Emirates&lt;/a&gt; has 221 planes, and covers a fancy 164 routes. In its home country as well, the biggest player &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_India&quot; rel=&quot;nofollow&quot;&gt;Air India&lt;/a&gt; has 102 planes and covers 95 routes. So, what are these LCCs planning to do with so many aircraft? Renting could be an idea, but you just do not go for renting as much as 4 times of your crew size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;AirAsia has ordered 304 A320s,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;EasyJet has ordered 100 A320s,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;RyanAir has ordered 100 B-737.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Norwegian has ordered 100 A320s, 100 B737,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-16T00:22:42.837" LastActivityDate="2020-04-02T09:56:27.713" Title="Why are Low Cost Carriers ordering several hundred aircraft?" Tags="&lt;commercial-aviation&gt;&lt;cost&gt;&lt;commercial-operations&gt;&lt;low-cost-carrier&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15546" PostTypeId="2" ParentId="15477" CreationDate="2015-06-08T10:29:20.613" Score="2" Body="&lt;p&gt;Two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When a model is suspended in a magnetic field, and then the wind tunnel is switched on, you'll see a change in the force along 'y-axis' (The lift forces) and change in force along 'x-axis' (The drag forces). Hence, you'll need a complex mechanism for sensing this forces, and changing the magnetic field in such a way that the change in forces is compensated by the 'change in magnetic field' so that the model does not translate in any of these directions and stays static. Then you'd measure the change in magnetic field to measure the forces, and hence the system becomes expensive and cumbersome.&lt;/li&gt;&#xA;&lt;li&gt;For pressure measurements, you'd have to use wireless sensors on the pitot ports, as you dont want tubes dangling form the suspended models. This makes the process more cumbersome and expensive&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This is why the magnetic suspension is not used every where, as the cost to accuracy ratio in normal wind tunnels is much less than the ratio in magnetically suspended models of magnetic wind tunnels&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-08T10:29:20.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15547" PostTypeId="5" CreationDate="2015-06-08T10:33:01.513" Score="0" Body="&lt;p&gt;Any questions related to the Aircrafts manufactured by Fairchild Aircraft should be tagged under this tag.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-08T13:09:12.043" LastActivityDate="2015-06-08T13:09:12.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15548" PostTypeId="4" CreationDate="2015-06-08T10:33:01.513" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-08T10:33:01.513" LastActivityDate="2015-06-08T10:33:01.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15549" PostTypeId="2" ParentId="15545" CreationDate="2015-06-08T10:33:32.493" Score="15" Body="&lt;h2&gt;Volume Orders Discounts&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These result in significant discounts to the airline. While discounts are commonplace in the industry, Ryanair ordered 737-800 for an estimated 40-50 million dollars as compared to the list price of around 90 million dollars. With an order of that size Boeing could not risk losing it to another manufacturer, and will be satisfied with less profit per aircraft. &lt;a href=&quot;http://www.forbes.com/sites/davidewalt/2013/03/19/boeing-lands-a-15-6-billion-737-order-from-ryanair/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fleet strategy:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some airlines sell their old aircraft after only a few years while their value is still high but the maintenance costs start to increase. Increased maintenance is bad when you try to squeeze out as many flights as possible and you have small profit margins on every flight. You can find some of Ryanair's old aircraft by the company code (AS) with other operators by searching 737-8AS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another &lt;a href=&quot;http://centreforaviation.com/analysis/ryanair-swot-analysis--michael-olearys-maniacal-focus-on-being-the-lowest-cost-producer-96465&quot; rel=&quot;nofollow&quot;&gt;suggestion&lt;/a&gt; is that the customers perception of Low-Cost airlines is generally negatively biased and having new aircraft counters this effectively.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Old Aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some operators (such as charter operators) will not have the same sensitivity to a slightly higher fuel consumption on their aircraft. They may not use their aircraft the same number of hours, so having an increasingly expensive jet sitting on the ground is not cost-efficient. The aircraft ordered by IndiGo are all new fuel efficient A320NEO.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some of these ideas are emphasized in your link.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Of its 530 orders from IndiGo, Airbus has so far delivered 99 aircraft. The airline currently has a fleet of 83 planes and has phased out 16 planes that were over six year old or among the first in its fleet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A bit of Ryanair strategy is outlined in &lt;a href=&quot;https://www.ryanair.com/doc/investor/Strategy.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1696" LastEditDate="2015-06-16T17:31:13.600" LastActivityDate="2015-06-16T17:31:13.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15550" PostTypeId="2" ParentId="15545" CreationDate="2015-06-08T10:35:40.310" Score="11" Body="&lt;p&gt;It might be that Times of India are over-reporting the actual orders. The aircraft industry has various types of orders and options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other sources (&lt;a href=&quot;http://www.pdxlight.com/neomax.htm&quot;&gt;pdxlight&lt;/a&gt;) say that Indigo has firm orders for 180 A320neos. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If Indigo replaced their existing A320s this would represent a doubling of their fleet size - still surprising but less so than the five-fold increase from 99 to 530 suggested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indigo have also signed a &lt;a href=&quot;http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/indigo-signs-mou-for-250-a320neo-aircraft/&quot;&gt;memorandum of understanding for 250 aircraft&lt;/a&gt;. This isn't a firm order. Indigo claim &quot; The additional aircraft will enable us to continue to bring our low fares and courteous, hassle free service to more customers and markets and will create more job opportunities and growth.&quot; - presumably if their ambitious expansion plans do not work out as expected, this MoU will not be converted into firm orders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been reports of an IPO for Indigo and other sources of funding.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-08T10:53:01.563" LastActivityDate="2015-06-08T10:53:01.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15551" PostTypeId="1" AcceptedAnswerId="15560" CreationDate="2015-06-08T10:49:33.040" Score="6" ViewCount="799" Body="&lt;p&gt;Tip jet refers to the jet nozzles at the tip of some helicopter rotor blades, to spin the rotor. What is their working principle?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-04T11:13:15.673" LastActivityDate="2016-07-04T11:13:15.673" Title="What is the working principle of tip jets?" Tags="&lt;helicopter&gt;&lt;tip-jets&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15552" PostTypeId="5" CreationDate="2015-06-08T10:50:21.727" Score="0" Body="&lt;p&gt;This tag is mainly regarding questions regarding 'Helicopter Blade Tip Jets'&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-08T13:32:59.507" LastActivityDate="2015-06-08T13:32:59.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15553" PostTypeId="4" CreationDate="2015-06-08T10:50:21.727" Score="0" Body="Tip jet refers to the jet nozzles at the tip of some helicopter rotor blades, to spin the rotor, much like a Catherine wheel firework." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-08T13:15:30.367" LastActivityDate="2015-06-08T13:15:30.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15554" PostTypeId="5" CreationDate="2015-06-08T10:54:22.197" Score="0" Body="&lt;p&gt;The spoiler causes the &lt;a href=&quot;/questions/tagged/airflow&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airflow&amp;#39;&quot; rel=&quot;tag&quot;&gt;airflow&lt;/a&gt; over the &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt; to separate from the portion of the wing behind the spoiler, greatly reducing the &lt;a href=&quot;/questions/tagged/lift&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lift&amp;#39;&quot; rel=&quot;tag&quot;&gt;lift&lt;/a&gt; generated by that wing section. Spoilers fall into two categories: those that can be deployed at controlled angles during flight to increase descent rate or control &lt;a href=&quot;/questions/tagged/roll&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;roll&amp;#39;&quot; rel=&quot;tag&quot;&gt;roll&lt;/a&gt;, and those only intended to be used on landing to quickly reduce lift and increase &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt;.  Spoilers that can be used in flight are known, naturally, as &lt;em&gt;flight spoilers&lt;/em&gt; (spoilers used to provide roll control are also known as &lt;em&gt;spoilerons&lt;/em&gt; or &lt;em&gt;roll spoilers&lt;/em&gt;), while those used only on the ground are known, surprisingly enough, as &lt;em&gt;ground spoilers&lt;/em&gt;.  (Most flight spoilers also function as ground spoilers to some extent, as their maximum deflection is limited in flight, with the spoilers only popping up to their fully-extended position upon touchdown.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilers differ from &lt;a href=&quot;/questions/tagged/airbrakes&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbrakes&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbrakes&lt;/a&gt; in that airbrakes are designed to increase drag without affecting lift, while spoilers reduce lift as well as increasing drag.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-09-29T10:10:41.690" LastActivityDate="2019-09-29T10:10:41.690" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15555" PostTypeId="4" CreationDate="2015-06-08T10:54:22.197" Score="0" Body="Spoilers are control surfaces which spoil the lift and increase the drag of a wing by disturbing the airflow around it." OwnerUserId="3386" LastEditorUserId="14897" LastEditDate="2019-02-27T23:35:41.403" LastActivityDate="2019-02-27T23:35:41.403" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15556" PostTypeId="5" CreationDate="2015-06-08T10:56:41.050" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-08T10:56:41.050" LastActivityDate="2015-06-08T10:56:41.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15557" PostTypeId="4" CreationDate="2015-06-08T10:56:41.050" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-08T10:56:41.050" LastActivityDate="2015-06-08T10:56:41.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15558" PostTypeId="5" CreationDate="2015-06-08T10:58:01.290" Score="0" Body="&lt;p&gt;Combustion is the act of fuel undergoing a high-temperature chemical reaction with oxidant (most commonly oxygen) in an exothermic redox reaction generating heat.&lt;/p&gt;&#xA;" OwnerUserId="8282" LastEditorUserId="8282" LastEditDate="2018-10-12T21:11:05.183" LastActivityDate="2018-10-12T21:11:05.183" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15559" PostTypeId="4" CreationDate="2015-06-08T10:58:01.290" Score="0" Body="For questions specifically about the process of burning fuel." OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-10-24T03:17:15.667" LastActivityDate="2019-10-24T03:17:15.667" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15560" PostTypeId="2" ParentId="15551" CreationDate="2015-06-08T11:33:25.530" Score="7" Body="&lt;p&gt;Tip jets spin the rotor by blowing out compressed air. It's the same principle as a jet engine or a jet-ski impeller, just that the exhaust is pushed out through the rotors. Some designs even had jet engines on the rotor tips! The primary advantage of the design are that there is no torque created, so no need for anti-torque rotors or thrusters, the tip jets also increase the rotor's moment arm and mass, making autorotation safer in some cases, although the drag from the tip jets often slowed the rotors down in many cases. Some say it is easier to learn to fly and safer to fly a tip jet design as there's no torque. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are very few systems which use tip rotors, the main disadvantages would seem to be a lack of efficiency and drag from the tip jets. The rotor design is complex as high-pressure air must be carried through them, causing many design and materials challenges. Also, lack of a tail rotor means there's no way to pivot in hover unless unless you put some sort of tail thruster on. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-06-08T11:33:25.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15561" PostTypeId="1" AcceptedAnswerId="15563" CreationDate="2015-06-08T11:35:12.060" Score="11" ViewCount="2296" Body="&lt;p&gt;I saw this picture in a local newspaper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RvEFk.jpg&quot; alt=&quot;Planes with exhaust trails&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My thoughts were, silly artists, that's the APU exhaust, it won't ever produce a trail like that during takeoff (or ever).&#xA;Of course, the picture is clearly photoshopped, as can be seen by the planes' outlines. But somebody didn't do the research :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to be sure, were my thoughts correct?&lt;/p&gt;&#xA;" OwnerUserId="3944" LastEditorUserId="19" LastEditDate="2016-11-01T22:26:58.103" LastActivityDate="2016-11-02T00:25:55.703" Title="Can an APU exhaust make a contrail in flight?" Tags="&lt;contrails&gt;&lt;apu&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15562" PostTypeId="2" ParentId="15561" CreationDate="2015-06-08T12:27:41.543" Score="7" Body="&lt;p&gt;You are right. Newspapers are rarely able to produce anything about aviation without letting their imagination fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, the APU doesn't produce contrails. Second, contrails don't start at the exhaust but at &lt;a href=&quot;https://aviation.stackexchange.com/a/15220/19&quot;&gt;a distance behind it&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-06-08T12:27:41.543" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15563" PostTypeId="2" ParentId="15561" CreationDate="2015-06-08T12:27:57.183" Score="20" Body="&lt;p&gt;APU may be used in flight as second source of power or bleed air if one of the engine systems is inoperative. If it is so used, it might leave a contrail the same way engines will, though as DeltaLima notes, it's exhaust is hotter and the air behind the fuselage is more turbulent, so the range of conditions where it will leave a contrail is narrower than for the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it is an exceptional situation, so it is extremely rare. Most of the time the APU is switched off once the engines are running and only switched on again after landing, because when engines are running, they provide everything the aircraft needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In B737NG (the lower aircraft in the picture), the APU can be used as bleed air source up to 17,000 ft. This is too low for normal cruise, but if bleed system fails, pilots will descend to this altitude and start APU to provide air-conditioning for the remainder of flight to a suitable nearby airport. It can also be used up to 41,000 ft as power source, so the aircraft may cruise with one generator inoperative and running APU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In A320 (the upper aircraft in the picture), the APU can be used together with one bleed air system up to 20,000 ft and for power generation up to 41,000 ft. So again, the aircraft may cruise with one generator inoperative and running APU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Normally there would never be contrail behind APU and none behind engines unless both engines failed and APU was started as backup power source (&lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow noreferrer&quot;&gt;US1549&lt;/a&gt; did start APU when the engines failed, though it is unlikely there was contrail at that altitude).&lt;/li&gt;&#xA;&lt;li&gt;Contrail does &lt;em&gt;not&lt;/em&gt; start right behind the engines. The water in the exhaust needs some time to cool down and freeze &lt;a href=&quot;https://aviation.stackexchange.com/a/15220/19&quot;&gt;before the contrail becomes visible&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-08T18:34:19.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15564" PostTypeId="1" AcceptedAnswerId="15593" CreationDate="2015-06-08T15:02:44.010" Score="12" ViewCount="3179" Body="&lt;p&gt;Lets say two different airports have the same number of runways, and terminals capable of handling any number of passengers. I realise that year round climate may have an effect on the number of days that planes may be able to land. But are there any other major factors which are able to make a big difference to the number of passengers those airports would be able to process? &#xA;For example, do the placement of runways interfere with air traffic control?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both make maximum use of their capacity, is it likely that both would have very similar numbers of annual passengers?&lt;/p&gt;&#xA;" OwnerUserId="8791" LastEditorUserId="19" LastEditDate="2017-01-04T15:27:25.703" LastActivityDate="2018-02-22T07:47:50.490" Title="Is the airport capacity related to number of runways?" Tags="&lt;runways&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15565" PostTypeId="2" ParentId="15477" CreationDate="2015-06-08T15:21:49.590" Score="2" Body="&lt;p&gt;At least in the case of the U.S., almost all of our wind tunnels were build decades ago before the technology was available to do this. I used to work at the USAF base that has most of the US wind tunnels. Most of them are quite old. One of them was actually taken from NAZI Germany after the war, though I think that one is mothballed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the reasons they aren't widely used, these come to mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It's a lot more complicated to design and build. In engineering, you normally choose the less complicated solution if it's good enough. Apparently the existing ones are good enough because we've been using them quite effectively for several decades.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I'm sure it would require an enormous magnetic field, as those models can be quite large (several meters) and, thus, quite heavy. Given all of the very sensitive sensors in the tunnels, it would likely be a pain to keep the field from interfering with the rest of the electronics. This is especially true in the engine testing tunnels, since the engines themselves are full of electronics nowadays. Almost everything in modern jet engines is electronically controlled.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-06-08T19:45:18.033" LastActivityDate="2015-06-08T19:45:18.033" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15567" PostTypeId="1" CreationDate="2015-06-08T15:39:04.343" Score="0" ViewCount="260" Body="&lt;p&gt;The USA has developed numerous aircraft; Sweden developed the &lt;a href=&quot;http://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;nofollow&quot;&gt;JAS Gripen&lt;/a&gt; and France developed the &lt;a href=&quot;http://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;nofollow&quot;&gt;Rafale&lt;/a&gt;, by themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But most of the modern aircraft developed by the UK and Germany needed collaborations. Yet both of them have the technology and enough money to build aircraft on their own. Why did the &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow&quot;&gt;Eurofighter&lt;/a&gt; need collaboration among four countries?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand being a collaborative effort, the F-35 became one of the most problematic projects in aircraft history. So why collaborate?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="97" LastEditDate="2015-06-08T16:41:32.200" LastActivityDate="2015-06-08T16:41:32.200" Title="Why are some aircraft built in a single country, whereas others are a collaboration of many countries?" Tags="&lt;aircraft-design&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-06-08T17:58:00.490" ContentLicense="CC BY-SA 3.0" />
  <row Id="15568" PostTypeId="1" AcceptedAnswerId="15571" CreationDate="2015-06-08T15:49:04.067" Score="16" ViewCount="10806" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;noreferrer&quot;&gt;F-16&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;noreferrer&quot;&gt;F-35&lt;/a&gt;, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;noreferrer&quot;&gt;Gripen&lt;/a&gt; have single engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the &lt;a href=&quot;https://en.wikipedia.org/wiki/AIDC_F-CK-1_Ching-kuo&quot; rel=&quot;noreferrer&quot;&gt;Ching-kuo&lt;/a&gt; (Taiwan) and &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;F/A-18&lt;/a&gt; have double engines, but the combined thrust of two engines is almost equal to the single engine thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do some aircraft use double engines? &lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="774" LastEditDate="2015-06-09T02:49:19.693" LastActivityDate="2017-10-08T03:42:31.280" Title="Why do some fighters have two engines and other have only one but still give the same performance?" Tags="&lt;jet-engine&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15569" PostTypeId="2" ParentId="15567" CreationDate="2015-06-08T16:27:42.463" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why did Eurofighter need collaboration among four countries?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For production volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are still in an era of relatively low-volume high-value combat aircraft compared to the early years (say pre 1950).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cost per unit is less if the development costs are spread over a greater number of manufactured units.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Individual European nations each have requirements for relatively small numbers of aircraft. If they each develop and manufacture their own aircraft, costs to each are likely to be higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Politically, it is easier to sell a military aircraft to politicians whose countries benefit from the manufacturing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also benefits in sharing development costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the close economic, political and military ties between European countries, collaboration makes sense.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-08T16:32:56.470" LastActivityDate="2015-06-08T16:32:56.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15570" PostTypeId="2" ParentId="15568" CreationDate="2015-06-08T16:48:57.497" Score="7" Body="&lt;p&gt;Very early jet engines weren't particularly powerful; it took two in most cases to equal (or slightly exceed) the performance of a single big V-12 or large radial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next generation was more capable; most fighters in Korea and many in Vietnam were single-engined. Some exceptions were quite large – the &lt;a href=&quot;http://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot;&gt;F-4 Phantom&lt;/a&gt; and &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_A-5_Vigilante&quot;&gt;(R)A-5 Vigilante&lt;/a&gt; come to mind. The more combat load required, the more thrust, and a single engine able to power an F-4 Phantom would've likely been &lt;em&gt;quite large&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern engines are much more capable; it mostly comes down to the desires of the operators. A single engine requires less maintenance (although probably not half) than a twin-engine aircraft. &lt;strong&gt;It is also more susceptible to mechanical failures or combat damage.&lt;/strong&gt; The need for larger combat loads, redundancy, and —in some cases— excess performance are probably the primary reasons that not all modern fighters are single-engined.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-08T16:48:57.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15571" PostTypeId="2" ParentId="15568" CreationDate="2015-06-08T16:55:36.780" Score="12" Body="&lt;p&gt;Some countries don't get the most powerful engines and have to use what is available in the market. To avoid upsetting China too much, the US would not sell the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_F404&quot;&gt;F404&lt;/a&gt; or the &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F100&quot;&gt;F100&lt;/a&gt; to Taiwan, and a derivative of a &lt;a href=&quot;http://en.wikipedia.org/wiki/Garrett_TFE731&quot;&gt;civilian engine&lt;/a&gt; had to be developed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second reason is redundancy: When the US Navy had to decide between the &lt;a href=&quot;http://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot;&gt;F-16&lt;/a&gt; and what &lt;a href=&quot;http://en.wikipedia.org/wiki/Northrop_YF-17&quot;&gt;was to become the F-18&lt;/a&gt;, they preferred the design with two engines, because losing your only engine over water is a much more life-threatening experience than losing it over land. Similarly, the Eurofighter was designed more for peace than for war - having two engines will reduce training losses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, a single, bigger engine will be more powerful and more efficient per unit of mass, because manufacturing tolerances will be relatively smaller in the bigger engine, if the same technology is used for both. Single engines need to have more system redundancy than one of a pair of engines, so some of that advantage cannot be transferred into the finished design. Nevertheless, from a performance standpoint the single engine fighter will look better.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-08T17:03:46.360" LastActivityDate="2015-06-08T17:03:46.360" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="15572" PostTypeId="1" CreationDate="2015-06-08T17:06:19.673" Score="3" ViewCount="217" Body="&lt;p&gt;The Aero L-39 Albatros had great success in the past.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why didn't the later versions of AeroVodocody L-39 Albatross find much marketing success in the post-cold war modern aircraft market, like Aermacchi M-346, BAE Hawk, Korean T-50 golden eagle, Hongdu JL-8, and so on?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorDisplayName="user8792" LastEditDate="2015-06-10T14:54:02.240" LastActivityDate="2015-06-10T14:54:02.240" Title="Why did the later versions of AeroVodocody L-39 Albatross find much market success?" Tags="&lt;fighter&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-06-08T20:14:13.190" ContentLicense="CC BY-SA 3.0" />
  <row Id="15573" PostTypeId="2" ParentId="15572" CreationDate="2015-06-08T17:55:24.517" Score="2" Body="&lt;p&gt;&lt;strong&gt;It was, although it's not in widespread use.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The L-39 was developed into the L-59 and from that into the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aero_L-159_Alca&quot; rel=&quot;nofollow noreferrer&quot;&gt;L-159 Alca&lt;/a&gt;. It's radar-equipped, can carry just over 5,000lb (2,340 kg) of air-to-air and air-to-ground weapons, and is in service with the Czech Air Force. According to Wikipedia, 72 were built between 1997 and 2003.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vuKWP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that it's an aircraft designed in the former USSR's influence, it's not unsurprising that it didn't get a lot of customers. Russia prefers to buy Russian; Russia's friends &lt;em&gt;also&lt;/em&gt; prefer to buy Russian. America's friends are strongly encouraged &lt;em&gt;not to buy anything that isn't American&lt;/em&gt;. And thus a small Czech single-seater is not likely to become very popular.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-08T17:55:24.517" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15575" PostTypeId="1" AcceptedAnswerId="15580" CreationDate="2015-06-08T18:30:08.020" Score="36" ViewCount="6093" Body="&lt;p&gt;Is the correct stall recovery action somehow counter-intuitive? I've read about crashes like Colgan Air 3407 where pilots experiencing a stall have done the exact wrong thing and pitching the nose up. It makes me wonder if pitching down does not feel right to a person.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not being a pilot I can only relate it to driving a car. You're taught that to recover from a skid you should steer into it. An inexperienced driver will be in a turn, feel a skid and turn the wheel further into the turn resulting in loss of control. You have to teach yourself to overcome that instinctive reaction and remember what you were trained to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the reaction to a stall similar? When you feel the a/c lose lift and start dropping is it an instinctive reaction to try to climb? You're going down and you want to go up so you pull back. Do you have to teach yourself to overcome a reflex to use proper recovery technique?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so do airline pilots practice stall recovery in a simulator? I know it took me a bit of practice in an icy parking lot to make skid recovery come naturally.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-07-18T20:27:40.133" LastActivityDate="2016-07-19T02:38:18.573" Title="Is a pilot's instinctive reaction to a stall counter-intutive?" Tags="&lt;flight-training&gt;&lt;stall&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15576" PostTypeId="2" ParentId="15575" CreationDate="2015-06-08T19:05:41.053" Score="17" Body="&lt;p&gt;There are a few issues. First off everyone that has a pilots license (in the US at least) has stalled an aircraft (generally a trainer), its a requirement for obtaining the license. Commercial pilots also receive spin awareness and recovery training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be noted (as its sometimes overlooked) &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Stall can occur at &lt;strong&gt;&lt;em&gt;ANY&lt;/em&gt;&lt;/strong&gt; airspeed&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_%28fluid_mechanics%29&quot;&gt;stall by definition&lt;/a&gt; is when there &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...is a reduction in the lift coefficient generated by a foil as angle&#xA;  of attack increases&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You are correct that sometimes people pull back on the controls (nose up) when a stall occurs. This is why stick shakers and pushers exist. Its not very instinctive to push the stick and subsequently dive the airplane towards the only real obstacle, the ground. The problem, sometimes is recognizing that the aircraft is stalling (one of the issues in the &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Air France 447&lt;/a&gt; crash) failure to do this can lead to the pilot making the wrong corrective action because they don't know what is really happening to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of 3407 it seems the pilots first mistake was not maintaining proper approach speed. The second mistake was not applying full throttle during the recovery and pitching the aircraft up to much. This put the plane into the stall which they could not recover. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although only touched on in the Wiki article, the pilots did report Ice (although de-ice was activated) it should be noted that ice build up on the wings alters the stall and flight characteristics of a plane. On a similar note, both wings often &lt;a href=&quot;http://www.experimentalaircraft.info/flight-planning/aircraft-stall-effect.php&quot;&gt;do not stall at the same time&lt;/a&gt;. The drop a single wing during a stall can also lead to counter control that causes issues.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-08T19:05:41.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15577" PostTypeId="2" ParentId="15545" CreationDate="2015-06-08T19:47:16.473" Score="2" Body="&lt;p&gt;Outfitting an airline with a single, modern type will yield the lowest operating cost once financing of the acquisition is secured and crew compensation stays low. This, together with the rebates connected to a big order, enables the airline to win any price war with its local competition, because its aircraft will consume less fuel and will be profitable at lower seat-mile prices than those of a competitor which operates a mixed fleet of different types and older aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the investor needs only some patience, and after a few years of losses he will be able to reap monopoly profits. This, at least, is the strategy behind such big orders of a single type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By ordering large volumes, the airline can secure the highest possible rebates (up to 50%). This strategy is very similar to that of car rental firms which also buy cars in large volumes and with substantial rebates in order to sell them after some months (years in case of airlines) for more than they paid for them.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-02T09:56:27.713" LastActivityDate="2020-04-02T09:56:27.713" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15579" PostTypeId="2" ParentId="15575" CreationDate="2015-06-08T22:00:56.420" Score="5" Body="&lt;p&gt;Just to second Dave's answer, typically a pilot who pulls up in stall does not realize that they have stalled and are just blindly reacting to a loss in altitude. To answer your specific questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Do you have to teach yourself to overcome a reflex to use proper recovery technique?&lt;/em&gt;&lt;/strong&gt; Not really. Most dangerous stall situations are confusing enough that there is no &quot;reflex&quot;, it's just a question of whether the pilot is calm enough to use their training and knowledge. An untrained person will just freeze or manipulate the controls wildly, there is no &quot;reflex&quot;. Most fatal stalls occur close to the ground where even the correct reaction will come too late or in low-visibility conditions in which the pilot cannot see the horizon. It is pretty rare for a pilot who can see the horizon and has plenty of altitude to stall all the way to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main benefit of training is not to overcome a reflex, it is to learn to react &lt;strong&gt;quickly&lt;/strong&gt; to the situation, so you spend less time figuring out what is going on and react faster. Every pilot knows to push the stick forwards in a stall; the question is how fast do they realize they are stalled, and how fast do they react once they realize that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;...do airline pilots practice stall recovery in a simulator?&lt;/em&gt;&lt;/strong&gt; Yes.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-08T22:00:56.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15580" PostTypeId="2" ParentId="15575" CreationDate="2015-06-08T22:14:18.283" Score="31" Body="&lt;p&gt;The correct way to recover from a stall is counter intuitive, not because pilots are trying to climb, but because the nose of the airplane drops due to the loss of lift and aircraft design.  99.999% of the time (when the aircraft is not in a stall), if the nose drops, you simply pull back in order to raise it and this muscle memory is built over time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, if the aircraft has stalled, pulling back will only worsen the situation and you need to push forward in order to gain sufficient airspeed for a recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, stall recovery is taught in both primary training, and during simulator training for pilots, although not typically to a full stall in the simulator.  Instead, the aircraft is slowed to the &lt;em&gt;first indication of a stall&lt;/em&gt; which may be a stall warning system instead.  At this point they are expected to apply the correct stall recovery techniques recommended by the manufacturer / their SOP's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a fairly large difference between recovering from a stall in a training environment because you know that it is coming and already know what you are going to do when it happens.  A large part of stall training is for &lt;strong&gt;&lt;em&gt;stall recognition&lt;/em&gt;&lt;/strong&gt; so that hopefully if it were to happen outside the training environment, the pilot will recognize the warning signs before it happens and can apply the proper stall recover technique before the aircraft enters a full stall.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, out &quot;in the real world&quot; most unplanned stalls that occur happen because the pilot is distracted by something else and they aren't expecting it. That lack of anticipation sometimes causes them to fall back on muscle memory and pull up just because the nose fell without realizing what happened.  This can be more likely when the stall doesn't happen quite like it does in training.  In some situations there may be fewer warning signs, or a component of the stall warning system isn't working as expected and can delay the realization that they are in a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information on what a stall is and why pilots practice them, see another question that was asked before here: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1418/what-happens-when-an-airplane-stalls-and-why-do-pilots-practice-it/1422#1422&quot;&gt;What happens when an airplane stalls and why do pilots practice it?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-06-09T20:23:43.093" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15581" PostTypeId="1" AcceptedAnswerId="15584" CreationDate="2015-06-08T23:27:06.750" Score="15" ViewCount="11000" Body="&lt;p&gt;I've heard of many different types of controllers, but I'm not sure exactly what their responsibilities and interactions are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;En route controllers&lt;/li&gt;&#xA;&lt;li&gt;Approach controllers&lt;/li&gt;&#xA;&lt;li&gt;Ground controllers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What types of controllers exist and what aspects of a flight is each one responsible for?&lt;/p&gt;&#xA;" OwnerUserId="8794" LastActivityDate="2018-01-24T14:24:51.020" Title="What types of air traffic controllers are there?" Tags="&lt;air-traffic-control&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15582" PostTypeId="2" ParentId="15581" CreationDate="2015-06-08T23:46:24.727" Score="10" Body="&lt;p&gt;You can &lt;s&gt;&lt;a href=&quot;https://www.faa.gov/jobs/career_fields/aviation_careers/atc_roles/&quot; rel=&quot;nofollow noreferrer&quot;&gt;find a nice summary here on the FAA website&lt;/a&gt;&lt;/s&gt; or &lt;a href=&quot;http://en.wikipedia.org/wiki/Air_traffic_control#Approach_and_terminal_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;here on Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But generally speaking, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At an Airport (and this very much varies by airport size!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: if there is no tower at an airport (the case for many small airports) aircraft must &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2013.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;self announce&lt;/a&gt; on the &lt;a href=&quot;http://en.wikipedia.org/wiki/UNICOM&quot; rel=&quot;nofollow noreferrer&quot;&gt;UNICOM Frequency&lt;/a&gt;. It should also be mentioned that some airports have towers that are only in operation some hours of the day, they are considered (if open) un-towered at other times. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be a Tower controller (if there is a tower): who deals with airplanes on, to and from the active runways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There could be a designated ground controller who deals with traffic form the ramp to the runway (at KPNE where I fly the tower handles the ground operations during low load times). They will also handle the movements of other things like plows and service vehicles that may be active on or near the runway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be Flight Data/Clearance Delivery who will give the planes their routes before departure (or any taxiing) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Terminal Controllers handle traffic in the radar terminal area (30-50 miles) from an airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Enroute Controllers provide information to airplanes in the air such as IFR instructions or VFR Flight Following (Load Permitting) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find the frequencies for the various ATC bodies in the Airport Facilities Directory. You can even &lt;a href=&quot;http://www.liveatc.net/&quot; rel=&quot;nofollow noreferrer&quot;&gt;listen in live&lt;/a&gt; to see whats going on at lots of major airports.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="10076" LastEditDate="2016-12-28T14:01:33.740" LastActivityDate="2016-12-28T14:01:33.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15583" PostTypeId="2" ParentId="15564" CreationDate="2015-06-09T01:01:27.283" Score="8" Body="&lt;p&gt;This is a complicated question to answer but I'll try my best to give you an idea. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you say number of runways there are a few situations; this will vary based largely on wind as well as when and where the airport was built, but there are two main cases to consider. Keep in mind the wind may prevent the use of certain runways.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1: Side by side runways. Large airports like KPHL, KJFK, KORD (and even places similar in size to Van Nuys Airport) have parallel runways. This can greatly aid in throughput as two planes can &lt;a href=&quot;http://en.wikipedia.org/wiki/Simultaneous_opposite_direction_parallel_runway_operations&quot; rel=&quot;noreferrer&quot;&gt;land/takeoff simultaneously&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2: &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.652_Converging_Runway_Operations.pdf&quot; rel=&quot;noreferrer&quot;&gt;Intersecting Runways&lt;/a&gt;. In this case you still have two runways but they will cross each other and depending on aircraft size cannot be used simultaneously. If the airport supports GA or the runways intersect towards their respective ends a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Land-and-Hold-Short-Operations-LAHSO&quot; rel=&quot;noreferrer&quot;&gt;land and hold short&lt;/a&gt; may be possible. With intersecting runways you would, in theory, have less options since you can't have the simultaneous situation you do with parallel runways. &lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Other Factors&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Size&lt;/a&gt;: another thing to consider is runway length and aircraft size. Generally speaking runways at a given airport are often of different sizes. As such some aircraft may require a specific runway, if, on a given day you happen to only be landing large aircraft you may only be able to make use of one of your two parallel runways even though both are useable in the current wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Taxiway&quot; rel=&quot;noreferrer&quot;&gt;Taxi Ways&lt;/a&gt;: for what it's worth I would not think taxi ways are a limiting factor in airport design. They often are the place where the queue builds up but generally are not the cause of the queue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Ground_support_equipment&quot; rel=&quot;noreferrer&quot;&gt;Ground Crew/Ground Resources&lt;/a&gt;: If we are talking strictly commercial operations it takes time and resources to turn a plane around (get it back in the air). The plane may need fuel or a de-ice (de-ice facilities have gotten better and are usually near the runway now). You may need a tug, a crew to load the plane, food, cleaning &amp;hellip; you get the idea. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=-z2o0acIlm4&quot; rel=&quot;noreferrer&quot;&gt;Physical Obstacles&lt;/a&gt;: Some airports are built in areas with tough terrain. This may cause all departures and takeoffs to come in from a single direction. This can limit the amount of traffic in and out of an area as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_noise&quot; rel=&quot;noreferrer&quot;&gt;Noise Abatement&lt;/a&gt;: With the growing concern for local communities and increasing noise of jet engines, some airports have growing restrictions on when you can and can't take off. I fly out of KPNE and they have restricted runway use on Sundays as well as no touch and go's at various times. In this case two airports with the same number of runways may have different throughput due to runway restrictions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Instrument_approach&quot; rel=&quot;noreferrer&quot;&gt;Runway Approach Systems&lt;/a&gt;: Not all airports have instrument approaches on all runways (or any runway for that matter, although with the addition of GPS approaches, more and more airports have some kind of approach). If the weather is bad the better equipped airport will always have a greater throughput (an ill-equipped airport may prevent landings all together, although that's unlikely for commercial airports these days).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The locale is a big factor as well; if you build a huge airport in an area that no one wants to go to or leave, it's not going to see much traffic. Likewise if you build a tiny airport in Central Park, chances are you will have a stream of planes heading to and from the Hamptons in the summer&amp;hellip;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="4474" LastEditDate="2015-06-13T15:12:18.753" LastActivityDate="2015-06-13T15:12:18.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15584" PostTypeId="2" ParentId="15581" CreationDate="2015-06-09T01:04:07.110" Score="17" Body="&lt;p&gt;In Canada (and I believe similarly in the United States), there are four ratings which can be applied to an Air Traffic Controller license:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airport Control&lt;/li&gt;&#xA;&lt;li&gt;Terminal Control&lt;/li&gt;&#xA;&lt;li&gt;Area Control&lt;/li&gt;&#xA;&lt;li&gt;Oceanic Control&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Within each of those ratings, the responsibilities are sub-divided a bit based on operational needs. For example, controllers at a tower (with an '&lt;strong&gt;Airport Control&lt;/strong&gt;' rating) would tend to be qualified in all aspects of tower operations including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Clearance Delivery (issuing IFR clearances or assigning transponder codes)&lt;/li&gt;&#xA;&lt;li&gt;Ground Control (issuing clearances for aircraft to move to/from the apron and runway areas via a taxiway system&lt;/li&gt;&#xA;&lt;li&gt;Air Control (issueing clearances to aircraft in the runway environment and in the vicinity of the airport)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Terminal Controllers&lt;/strong&gt; (if a terminal control area exists around the airport in question) would be responsible for flights in the immediate vicinity of the airport to approximately 20-50 nautical miles. Their responsibilities may include multiple small airports, just a single large airport, or even just one specific operation at an airport (such as arrival control or departure control). These controllers are usually allowed to apply a smaller amount of lateral separation between aircraft due to the dense nature of the terminal environment and the specific nature of their role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft leave the terminal (if one exists), the &lt;strong&gt;Area Controller&lt;/strong&gt;-sometimes called enroute control-takes over. They are responsible for anywhere between several hundred square miles of airspace to over several thousand square miles in the case of sectors in northern Canada. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of an aircraft transiting the ocean, a specific type of area controller called an &lt;strong&gt;Oceanic Controller&lt;/strong&gt; takes over. They possess slightly different training in order to safely separate aircraft over the ocean in non-radar airspace.&lt;/p&gt;&#xA;" OwnerUserId="287" LastActivityDate="2015-06-09T01:04:07.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15585" PostTypeId="2" ParentId="15541" CreationDate="2015-06-09T01:15:54.583" Score="1" Body="&lt;p&gt;Most aircraft utilize a weight on wheels switch. When the landing strut is compressed when ground contact is made, the weight on wheels switch is activated. The signal is distributed to various systems in the aircraft, including the spoiler system.&#xA;The spoiler is activated as soon as the aircraft touches the ground to &quot;scrub off&quot; any lift and to make sure the aircraft doesn't become airborne as the jet engines spool down.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2015-06-09T01:15:54.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15586" PostTypeId="1" CreationDate="2015-06-09T02:28:05.750" Score="12" ViewCount="11437" Body="&lt;p&gt;&lt;a href=&quot;https://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;n=14y2.0.1.1.2&amp;amp;r=PART#se14.2.61_165&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.65(d)(2)&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) Forty hours of actual or simulated instrument time in the areas of operation listed in paragraph (c) of this section, of which 15 hours must have been received from an authorized instructor who holds an instrument-airplane rating, and the instrument time includes:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So 15 hours must be with an instructor.  What about the other 25?  Can I fly in instrument meteorological conditions (IMC) &amp;quot;solo&amp;quot; (not the hood) like I did for my private pilot license (PPL) after an instructor sign off?  Or does this just mean that I need another instrument rated (IR) pilot with me, but it doesn't necessarily have to be a certified flight instructor (CFI)?  If that is the case, and I use the hood rather than actual IMC, does the other pilot need an IR or just a PPL?&lt;/p&gt;&#xA;&lt;p&gt;Basically, how do you fulfill the other 25 hours?&lt;/p&gt;&#xA;" OwnerUserId="8795" LastEditorUserId="62" LastEditDate="2020-06-29T02:23:33.803" LastActivityDate="2020-11-08T17:42:50.253" Title="How can I build the 40 hours instrument time required for an instrument rating?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="15587" PostTypeId="2" ParentId="15568" CreationDate="2015-06-09T04:07:47.710" Score="4" Body="&lt;p&gt;Number and placement of engines is one of the initial trade-offs that a scratch-built aircraft design deals with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several criteria for the trade-off of the basic configuration. Here are a few:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Thrust-to-AircraftWeight&lt;/li&gt;&#xA;&lt;li&gt;Weight penalty&lt;/li&gt;&#xA;&lt;li&gt;Aircraft Performance&lt;/li&gt;&#xA;&lt;li&gt;Stability/Control (agility)&lt;/li&gt;&#xA;&lt;li&gt;Survivability&lt;/li&gt;&#xA;&lt;li&gt;Reliability&lt;/li&gt;&#xA;&lt;li&gt;Maintenance intervals&lt;/li&gt;&#xA;&lt;li&gt;Time-to-replace&lt;/li&gt;&#xA;&lt;li&gt;Safety&lt;/li&gt;&#xA;&lt;li&gt;Inlet configuration (if it's down the aircraft, then FOD problems show up)&lt;/li&gt;&#xA;&lt;li&gt;Stealth (a single engine is bigger than two smaller engines (more&#xA; exhaust area))&lt;/li&gt;&#xA;&lt;li&gt;Cost of engines&lt;/li&gt;&#xA;&lt;li&gt;Cost of aircraft&lt;/li&gt;&#xA;&lt;li&gt;Provisions of the platform (to add future capabilities, and robustness to design changes)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;These and several other criteria (esthetics, marketing, etc) are used to judge the different configurations, and then one of them wins.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-09T04:07:47.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15588" PostTypeId="1" AcceptedAnswerId="15595" CreationDate="2015-06-09T06:55:34.650" Score="4" ViewCount="693" Body="&lt;p&gt;Indian Airforce conducts a test called PABT (Pilot Aptitude Battery Test), for anyone who wishes to be a pilot. This test can be taken only once, and once you fail it, you can never appear again (which inherently disqualifies you from being a pilot in the Indian Armed Forces). Why is such a test so important, and how does failing in it reflect on your piloting skills?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-10T06:39:29.983" LastActivityDate="2015-06-10T06:39:29.983" Title="What is the reason for allowing pilots to take Pilot Aptitude Battery Test (PABT) only once?" Tags="&lt;pilots&gt;&lt;pabt&gt;&lt;indian-air-force&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15589" PostTypeId="5" CreationDate="2015-06-09T06:56:30.660" Score="0" Body="&lt;p&gt;PABT (Pilot Aptitude Battery Test) are the combination of written and machine tests.   This type of PABT is followed throughout the world by all nations to choose pilot or air warriors for their nation.  The way of this varies for various nations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all the questions related to pilot tests throughout the Armed Forces in the world.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="65" LastEditDate="2015-06-09T13:09:29.803" LastActivityDate="2015-06-09T13:09:29.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15590" PostTypeId="4" CreationDate="2015-06-09T06:56:30.660" Score="0" Body="The PABT (Pilot Aptitude Battery Test) is conducted by the Air Force to choose candidates who want to join as pilot (Air Warrior) in Air Force Flying Branch. &#xD;&#xA;" OwnerUserId="8547" LastEditorUserId="65" LastEditDate="2015-06-09T13:09:44.467" LastActivityDate="2015-06-09T13:09:44.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15591" PostTypeId="5" CreationDate="2015-06-09T06:57:34.303" Score="0" Body="&lt;p&gt;The Indian Air Force (IAF; Devanāgarī: भारतीय वायु सेना, Bharatiya Vāyu Senā) is the air arm of the Indian armed forces. Its primary responsibility is to secure Indian airspace and to conduct Aerial warfare during a conflict. It was officially established on 8 October 1932 as an auxiliary air force of the British Empire and the prefix Royal was added in 1945 in recognition of its services during World War II.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-09T07:36:59.953" LastActivityDate="2015-06-09T07:36:59.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15592" PostTypeId="4" CreationDate="2015-06-09T06:57:34.303" Score="0" Body="For all questions regarding the Indian Air Force." OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-03-06T07:44:32.497" LastActivityDate="2019-03-06T07:44:32.497" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15593" PostTypeId="2" ParentId="15564" CreationDate="2015-06-09T07:50:48.383" Score="10" Body="&lt;h2&gt;Airport Capacity&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At major airports the capacity of the system of runways is the most restricting element. While it is usually possible to increase capacity of the other airport elements or adding a new runway (plus associated taxiways) is very expensive and takes a very long time to complete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway capacity is the principal cause of most extreme instances of delays that lead to widespread schedule disruptions, flight cancellations and missed flight connections. The runway capacity varies greatly from day to day and changes are difficult to predict (even a few hours in advance).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Factors:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The capacity of the runway system depends on several factors, the most important ones:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Mix of aircraft classes using the airport&lt;/strong&gt;: the aircraft mix indicates composition of aircraft fleet that is using any particular runway (e.g. 25% S, 60% L and 15% H).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Separation requirements imposed by the ATM system&lt;/strong&gt;: due to wind tip vortices, leading aircraft and trailing aircraft must be separated by a determined distance (Heavy aircraft are the ones that produce more wake turbulence).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Type and location of exits from the runway&lt;/strong&gt;: trailing aircraft of any pair cannot touch down on the runway before leading aircraft is clear of the runway. High-speed runway exits (also well placed runway exits) reduce runway occupancy times for arriving aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Mix of movements on each runway and the sequencing of the movements&lt;/strong&gt;: specified for all combinations of consecutive operations (arrival-departure). There's an important trade-off between maximum arrival and departure rates that an airport can achieve.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Lateral separation&lt;/strong&gt;: (especially in bad weather) between aircraft approaching the same airport on parallel runways.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Sequencing and separation of departing and landing aircraft on runways that intersect.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Sequencing of aircraft approaching airports located in close proximity to one another&lt;/strong&gt;, where one aircraft must cross the path of another aircraft landing at a nearby airport.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Direction and strength of winds&lt;/strong&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Noise-related and other environmental considerations and constraints.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Conclusion:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is difficult to predict the capacity of the runway system of an airport, so it is difficult to compare two airports with similar runway characteristics, since the factors depending on the airport capacity involve different design and operational parameters. Furthermore, everything is subject to the important probabilistic factor, the weather, which makes the prediction and comparison of airport capacity even more difficult.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="4474" LastEditDate="2015-06-13T15:12:04.310" LastActivityDate="2015-06-13T15:12:04.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15594" PostTypeId="2" ParentId="15391" CreationDate="2015-06-09T08:40:22.750" Score="5" Body="&lt;p&gt;Quote from the &lt;a href=&quot;http://www.thestar.com/business/2013/01/24/air_canada_pilots_can_continue_flying_past_age_60_under_new_rules.html&quot;&gt;source&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Under international aviation regulations, there must be at least one pilot under 60 in the cockpit at all times, and pilots over 65 cannot hold the captain position. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Specifically for Canada: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A new collective agreement, imposed by an arbitrator, sets out specific positions that pilots over 60 and over 65 can hold on Air Canada’s aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the sources &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1305&quot;&gt;Here&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2015/Gomez%20-%20%282015%29%20Legal%20Interpretation.pdf&quot;&gt;Here&lt;/a&gt;, its safe to say that the maximum age of 60 is applicable for some operations and for some it is 65. (For any airline operations to United States)&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-09T08:40:22.750" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15595" PostTypeId="2" ParentId="15588" CreationDate="2015-06-09T09:22:15.097" Score="6" Body="&lt;p&gt;A few thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They have no need in getting repeat candidates if the selection pool is  sufficient (which I imagine it is). Starting to accept repeat candidates would also make it harder for first timers, resulting in more work and tests for everybody. People also won't go for the fun of it, but will make their single attempt their best attempt.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I believe they would rather want you to nail it on the first attempt as part of the test. In other words: how do you respond to a new situation, how to you respond to the stress of knowing you have one attempt, etc... It would be effective for their purpose on multiple levels. This is more effective than you returning a second time and learning how to do the test.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While I can't comment on other air forces around the world, I know that German Lufthansa implements the same policy for acceptance.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-09T09:27:33.920" LastActivityDate="2015-06-09T09:27:33.920" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15598" PostTypeId="2" ParentId="15588" CreationDate="2015-06-09T12:21:17.413" Score="5" Body="&lt;p&gt;The goal of this kind of testing is mainly to identify those candidates who are most likely to succeed in pilot training and who can do so with minimal delays. Armed services (and airlines who offer cadet training) around the world sink tremendous amount of resources into training their pilots and are taking a significant financial and opportunity cost risk on each candidate, so proper selection critical. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designing tests meant to capture aptitude is no small task, and validation of the measurement instrument is an integral part of it, so it's probably safe to say that there is (or was at the time of design) at least some fairly significant support for correlation between performance on the battery and future performance as a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what it's worth, keep in mind that there are almost always more candidates than actual pilot slots. Failing to be selected for a slot doesn't necessarily mean that you aren't a good pilot or that you couldn't do the job, but rather that, at that particular moment in time, in the evaluator's opinion, there were other candidates who were better than you. To illustrate using a metaphor, all drivers competing in Formula 1 are excellent race car drivers, but only one of them can win the race.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-06-09T14:38:33.220" LastActivityDate="2015-06-09T14:38:33.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15599" PostTypeId="1" CreationDate="2015-06-09T12:52:44.377" Score="2" ViewCount="2072" Body="&lt;p&gt;In order to design the landing gear (wheels and suspension) of our model Airship, [say &quot;m&quot; kg -expected mass], I wanted to know, is there any way to calculate the loads which might be experienced by the wheels on impact with the ground (taking into consideration the unexpected gust loads - with gust velocity downwards say &quot;V-gust&quot;)• &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity I am Modelling it as a rigid body for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note:- I thought of one way to calculate it, using momentum transfer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rate of change of Momentum = Force = density(rho) x projected Area(A) x (V-gust)^2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence,( Gust force + Weight -Buoyant Force) ÷ Mass (m) will give me resultant acceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Q1. Is this a right approach to calculate load?&#xA;Q2. Even if it's right, is this the load the wheels will experience during impact?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please help me clear my confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:- Basically I want my designed landing gear with a normal sink speed upto 3m/s to be able to endure the landing impact even in case of an additional vertical downward gust upto 10m/s at the moment of touching the ground.  This is as specific and clear I could get. &lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="64" LastEditDate="2015-08-04T18:21:30.820" LastActivityDate="2015-08-04T18:21:30.820" Title="How would we calculate the load factor on an aerial vehicle while landing due to sudden gust loads?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;&lt;airship&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15600" PostTypeId="1" AcceptedAnswerId="15601" CreationDate="2015-06-09T14:05:57.487" Score="5" ViewCount="1441" Body="&lt;p&gt;The &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=3&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CDQQFjAC&amp;amp;url=http%3A%2F%2Fwww.usa.gov%2FAgencies%2Ffederal.shtml&amp;amp;ei=cPJ2VafzEJHk8AWBqIOAAw&amp;amp;usg=AFQjCNGiGhzajot8mlROf-Xi8pwG2bTd3w&amp;amp;sig2=6vfp9uinIjNCkVQacRp85w&quot; rel=&quot;nofollow noreferrer&quot;&gt;U.S. Federal Government&lt;/a&gt; has scores of old aircraft waiting for dismantling. Why doesn't it auction some of them? Some people might be very much interested in planes such as the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB4QFjAA&amp;amp;url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBoeing_B-52_Stratofortress&amp;amp;ei=T_J2VaL2K8zU8gWXkYCIDA&amp;amp;usg=AFQjCNFJKb2S56Mc7HFN104P-pUrrdZxEg&amp;amp;sig2=g0yJQIu22hDwL3PtBeYotA&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-52&lt;/a&gt;, and would be happy if they get it at some considerable price (though, I have no idea what it may be!) to keep them as a memorabilia. Also, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9411/can-civilians-fly-military-aircraft&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/9311/can-civilians-buy-military-aircraft&quot;&gt;this&lt;/a&gt; suggest that civilians can purchase and fly military aircraft. So why doesn't the federal government give this a shot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MLiFH.png&quot; alt=&quot;&quot;&gt;&#xA;&lt;a href=&quot;http://worldwideweasy.blogspot.in/2009/11/worlds-largest-aircraft-graveyard.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-10T14:38:29.240" Title="Why doesn't the U.S. Federal Government auction their retired but memorable aircraft?" Tags="&lt;aircraft-purchase&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15601" PostTypeId="2" ParentId="15600" CreationDate="2015-06-09T14:16:20.277" Score="6" Body="&lt;p&gt;There are a few reasons for this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off they may not want the public, or more importantly potentially enemy nations obtaining a large quantity (or any quantity for that matter) of military planes. Even old war birds can still do a lot of damage if equipped by a person with intent on doing damage.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, the boneyard you have pictured serves a few purposes. For one it houses aircraft that have reached their life time limit. To keep an airplane flying it takes not only money but a supply of parts (or the resources to make your own under certain FAA rules). Out of service planes may be tough if not impossible to keep flying for no other reason than you cant get airworthy parts for them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, some of the planes in these bone yards are scrapped (or kept there) for reserve parts for the planes still in service. Again airworthy parts are not as simple to get as going to your local car parts store. There are many more regulations around them. In this case you can pull parts from an airworthy plane (if you know the cycles its been through) and use them to fix another plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, and this is mainly speculation, maybe the government is hidings its back up planes in plane sight...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the note about buying old war birds, rules have changed over time and its not as easy to get ahold of government property as in days past. Some military equipment that sees its way to the public hands actually left the US as a sale to another country then that country sold it into public trade as well. For what its worth &lt;a href=&quot;http://www.trade-a-plane.com/search?s-type=aircraft&amp;amp;s-seq=3&amp;amp;s-lvl=3&amp;amp;special=warbird&amp;amp;s-np=&quot; rel=&quot;nofollow&quot;&gt;Trade-a-Plane&lt;/a&gt; has a whole section just for war birds. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-10T14:38:29.240" LastActivityDate="2015-06-10T14:38:29.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15602" PostTypeId="5" CreationDate="2015-06-09T14:18:34.580" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-09T14:18:34.580" LastActivityDate="2015-06-09T14:18:34.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15603" PostTypeId="4" CreationDate="2015-06-09T14:18:34.580" Score="0" Body="A low-cost carrier or low-cost airline (also known as a no-frills, discount or budget carrier or airline or cheap flight) is an airline that generally has lower fares and fewer comforts. To make up for revenue lost in decreased ticket prices, the airline may charge for extras like food, priority boarding, seat allocating, and baggage etc." OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-09T19:10:41.890" LastActivityDate="2015-06-09T19:10:41.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15604" PostTypeId="1" AcceptedAnswerId="15623" CreationDate="2015-06-09T14:33:45.620" Score="7" ViewCount="5333" Body="&lt;p&gt;I board an aircraft, wait for it to takeoff, then find the headphones somewhere near my seat plug them into the two-pin point, and it works! But, how does it works for hundreds of other passengers simultaneously? Where is all the content stored, how are the screens connected to it, and how powerful is the computer controlling so many screens? Also, why is IFE required to be connected to aircraft's main computing system, which may eventually lead to the &lt;a href=&quot;http://www.theregister.co.uk/2015/05/19/airplane_hacking_panic_why_its_a_surely_a_storm_in_a_teacup/&quot;&gt;hacking&lt;/a&gt; of an aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Side Question&lt;/strong&gt; : On an average, what is the size of content stored in a typical In-flight entertainment system?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-09T14:38:11.033" LastActivityDate="2015-06-10T08:40:14.033" Title="How does the in flight entertainment system works?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15605" PostTypeId="2" ParentId="13891" CreationDate="2015-06-09T16:40:24.353" Score="0" Body="&lt;p&gt;You need to apply for foreign FAA Repair station certificate under PART145 to your nearest Foreign FASDO (Flight Standards District filed office) . There are several steps one must take for compliance as per regulations including training.&lt;/p&gt;&#xA;" OwnerUserId="8800" LastEditorUserId="1467" LastEditDate="2015-06-09T17:17:24.863" LastActivityDate="2015-06-09T17:17:24.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15606" PostTypeId="1" CreationDate="2015-06-09T18:13:23.053" Score="4" ViewCount="1283" Body="&lt;p&gt;I have been playing with a SDR dongle. I have been able to decode some ACARS signals using SDR# and acarsd. I have noticed in my area (35 miles west of DFW airport) there are a number of frequencies used. I have been able to decode transmissions on 130.450, 131.125, and 131.475. Are there other common frequencies? What determines the frequency used by a particular plane? I find it odd that I can pick up an AA flight 30 miles away and yet when a similar flight passes directly overhead, I am unable to find their ACARS on any of those frequencies.&lt;/p&gt;&#xA;" OwnerUserId="8801" LastEditorUserId="19" LastEditDate="2016-07-04T11:14:10.533" LastActivityDate="2016-07-04T11:14:10.533" Title="What are the ACARS frequencies and what is their usage?" Tags="&lt;acars&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15607" PostTypeId="2" ParentId="15606" CreationDate="2015-06-09T18:32:00.877" Score="5" Body="&lt;p&gt;According to the &lt;a href=&quot;http://en.wikipedia.org/wiki/Aircraft_Communications_Addressing_and_Reporting_System&quot; rel=&quot;noreferrer&quot;&gt;specs&lt;/a&gt; ACARS supports direct to satellite linking so planes flying over you may not be broadcasting on one of those frequencies. Similarly, if broadcasting over VHF you are &lt;a href=&quot;http://en.wikipedia.org/wiki/Line-of-sight_propagation&quot; rel=&quot;noreferrer&quot;&gt;line of sight limited&lt;/a&gt;. At high altitudes you may see ranges up to 200 Nautical Miles however if the planes are low overhead they may not be broadcasting as they are out of sight of the possible ground station. Your dongle may also filter/ignore low power signals or it simply cant pick up certain signals due to their strength.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.acarsd.org/ACARS_frequencies.html&quot; rel=&quot;noreferrer&quot;&gt;Here is a list&lt;/a&gt; of common ACARS Frequencies. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-09T18:32:00.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15608" PostTypeId="2" ParentId="14354" CreationDate="2015-06-09T18:37:26.520" Score="4" Body="&lt;p&gt;The platform dropping the bombs becomes less and less important every year.  GPS guided bombs can strike a target with the same precision employed from any aircraft flying at 30,000 feet or above.  So the type of aircraft doesn't matter much, and it matters less and less as time passes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft has simply become a mule to get the bombs to the airspace above the target.  Being a dumb mule is a perfect role for an unmanned aircraft, so expect more drones to take over the bombing roles in future decades.  Unmanned aircraft will replace both fighters and strategic bombers in the bomber role.&lt;/p&gt;&#xA;" OwnerUserId="2141" LastActivityDate="2015-06-09T18:37:26.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15610" PostTypeId="2" ParentId="15599" CreationDate="2015-06-09T19:12:25.333" Score="1" Body="&lt;p&gt;If the question is about calculating the aerodynamic load acting on an airship, the answer is independent of the flight condition: whether it's landing, before touchdown, or after touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic load around the airship due to any gust, depends on the shape of the airship. Simply stated, the additional force due to gust would be:&#xA;&quot;CD * Ref_Area * V_gust&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This emprical formula gives a force, that must be reacted by the landing gears. However, note that, the main assumption is this: the gust is a steady airflow which is comparably larger than your Airship. In contrast, if the Airship is quite large, then the gust would probably affect only some local portion of the vehicle.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-09T19:12:25.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15611" PostTypeId="1" AcceptedAnswerId="15613" CreationDate="2015-06-09T19:36:21.617" Score="16" ViewCount="14248" Body="&lt;p&gt;&lt;a href=&quot;https://www.eaa.org/en/eaa/aviation-communities-and-interests/ultralights-and-ultralight-aircraft/getting-started-in-ultralight-flying/about-faa-part-103-for-ultralights&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 103&lt;/a&gt;.15 states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an ultralight vehicle over any congested area of a city, town, or settlement, or over any open air assembly of persons.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm wondering what is meant by &quot;congested area&quot;.  It sounds like you can fly over a city, town or settlement so long as it's not congested but...how is that defined?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2019-09-17T21:11:48.943" LastActivityDate="2019-09-17T21:11:48.943" Title="What is meant by a &quot;congested area of a city/town/settlement&quot; in FAR 103?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;ultralight&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="15612" PostTypeId="2" ParentId="15611" CreationDate="2015-06-09T19:49:13.350" Score="6" Body="&lt;p&gt;It is not explicitly defined in the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=69849ab2b06b66e687a197987b759c55&amp;amp;mc=true&amp;amp;node=pt14.1.1&amp;amp;rgn=div5&quot; rel=&quot;nofollow&quot;&gt;FAR Definitions&lt;/a&gt; and it seems the explicitly do not define it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would interpret (&lt;em&gt;please keep in mind this is my interpretation and not law&lt;/em&gt;) a congested area/assembly of people, as anywhere you could not safely land the aircraft in the event of an emergency without endangering others and or yourself. This may better by explained with an example. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets say you are flying low over main street at rush hour, your engine goes and you are forced to make an emergency landing. You have limited distance and direction to go and can not safely land the aircraft with out hitting either a building, people or vehicles on the road thus endangering them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that being said, you are correct that class B generally lies around the big cities in this country, and other cities may reside in class C, you can still have a congested area or open assembly of people (concert, state fare etc) in class G airspace.     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-10T18:47:59.567" LastActivityDate="2015-06-10T18:47:59.567" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15613" PostTypeId="2" ParentId="15611" CreationDate="2015-06-09T19:56:44.987" Score="12" Body="&lt;p&gt;I could not find a definite definition of &lt;strong&gt;congested area&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned &lt;a href=&quot;http://www.aerolegalservices.com/Articles/Congested%20Areas%20Under%20FAR%2091-119%202008-08-28.shtml&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] neither the FAA nor the NTSB has ever provided [...] a precise&#xA;  definition of [...] a &quot;congested area.&quot; Rather, a &quot;congested area&quot; is&#xA;  determined on a case-by-case basis. According to the Board, &quot;the&#xA;  determination must take into consideration all circumstances, not only&#xA;  the size of an area and the number of homes or structures, but, for&#xA;  example, whether the buildings are occupied or people are otherwise&#xA;  present, such as on roads.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same is echoed &lt;a href=&quot;https://blog.globalair.com/post/Wonder-What-The-Term-Congested-Area-Means-Some-FAA-Inspectors-Wonder-That-Too.aspx&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[For the definition of congested area,] FAA and the NTSB have opted&#xA;  for taking a &quot;case-by-case&quot; approach in determining how to apply&#xA;  certain terms.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;AOPA &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2006/April/200604_Departments_Legal_Briefing.html&quot;&gt;states that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Congested areas&lt;/strong&gt;. &quot;Over any congested area of a city, town, or settlement, or over any open air assembly of persons, an altitude of&#xA;  1,000 feet above the highest obstacle within a horizontal radius of&#xA;  2,000 feet of the aircraft.&quot; The FAA does not define congested area in&#xA;  the FARs or in the Aeronautical Information Manual. Interpretations in&#xA;  low-flight enforcement cases are not consistent for purposes of&#xA;  drafting a precise definition. Such a determination is usually decided&#xA;  on a case-by-case basis, and in the cases that we've seen, congested&#xA;  has been interpreted rather broadly. For example, a highway with&#xA;  moderate traffic was found to be &quot;congested,&quot; as was a seaside area&#xA;  where 200 to 300 persons were sitting on the beach or bathing in the&#xA;  water.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same can be seen &lt;a href=&quot;http://helicopterforum.verticalreference.com/topic/10915-congested-or-noncongested-that-is-the-question/&quot;&gt;here&lt;/a&gt;, and &lt;a href=&quot;http://happylandings.blogspot.com/2008/09/congested-area-definition.html&quot;&gt;here&lt;/a&gt;, and &lt;a href=&quot;http://www.agairupdate.com/article_detail.php?_kp_serial=00001267&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-09T19:56:44.987" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15614" PostTypeId="2" ParentId="15586" CreationDate="2015-06-09T19:59:16.547" Score="10" Body="&lt;p&gt;The remainder of the 25 hours can be completed with a Safety Pilot, a CFI, or a CFII. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A safety pilot must be able to act as PIC of the aircraft you are flying. Also, if the safety pilot is acting/desinated as PIC, both you and the safety pilot can log PIC time for when you are flying under the hood. If you are acting as PIC, the safety pilot can log SIC time for being a required flight crew member (FAR61.51(f)).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot file an IFR flight plan or fly in IMC unless a current Instrumented Rated pilot is on board and acts as PIC.&lt;/p&gt;&#xA;" OwnerUserId="8802" LastEditorUserId="26946" LastEditDate="2018-10-26T12:21:57.813" LastActivityDate="2018-10-26T12:21:57.813" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="15615" PostTypeId="2" ParentId="15599" CreationDate="2015-06-09T20:15:24.763" Score="2" Body="&lt;p&gt;You need at least the stroke of the tire-gear combination to calculate a load. If the airship contacts the ground with a velocity of $w$ and a mass of $m$, the impulse $m\cdot w$ needs to be absorbed by a force $F$ acting along the stroke $s$, as in $m\cdot w = F\cdot s$. Adding airship flexibility will greatly improve the accuracy of the result, because I suspect the hull will deform easily and add to the stroke.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need an example of how this is calculated for a Boeing 747, please click &lt;a href=&quot;https://aviation.stackexchange.com/questions/7889/how-much-force-does-a-747-land-with&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-06-09T20:15:24.763" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15616" PostTypeId="2" ParentId="15586" CreationDate="2015-06-09T20:37:44.763" Score="4" Body="&lt;p&gt;Here are the requirements for simulated instrument flight with a safety pilot, taken from 91.109. They only need a private certificate, along with the appropriate ratings in that category and class, but not instrument.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=260e87b2919c6aa5b5a87561f779ed6f&amp;amp;mc=true&amp;amp;node=sp14.2.91.b&amp;amp;rgn=div6#se14.2.91_1109&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.109&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;c) No person may operate a civil aircraft in simulated instrument&#xA;flight unless—&lt;/p&gt;&#xA;&lt;p&gt;(1) The other control seat is occupied by a safety pilot who possesses&#xA;at least a private pilot certificate with category and class ratings&#xA;appropriate to the aircraft being flown.&lt;/p&gt;&#xA;&lt;p&gt;(2) The safety pilot has adequate vision forward and to each side of&#xA;the aircraft, or a competent observer in the aircraft adequately&#xA;supplements the vision of the safety pilot; and&lt;/p&gt;&#xA;&lt;p&gt;(3) Except in the case of lighter-than-air aircraft, that aircraft is&#xA;equipped with fully functioning dual controls. However, simulated&#xA;instrument flight may be conducted in a single-engine airplane,&#xA;equipped with a single, functioning, throwover control wheel, in place&#xA;of fixed, dual controls of the elevator and ailerons, when—&lt;/p&gt;&#xA;&lt;p&gt;(i) The safety pilot has determined that the flight can be conducted&#xA;safely; and&lt;/p&gt;&#xA;&lt;p&gt;(ii) The person manipulating the controls has at least a private pilot&#xA;certificate with appropriate category and class ratings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8803" LastEditorUserId="-1" LastEditDate="2020-11-08T17:42:50.253" LastActivityDate="2020-11-08T17:42:50.253" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15617" PostTypeId="1" AcceptedAnswerId="15622" CreationDate="2015-06-09T22:51:27.540" Score="12" ViewCount="151" Body="&lt;p&gt;I know that you need a certain certification to fix a plane, but are you required to have a certification to fix a runway?  Or can anyone with the proper equipment be paid to do it?&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-06-10T08:25:42.210" Title="Is certification required to conduct runways repairs?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15618" PostTypeId="2" ParentId="15575" CreationDate="2015-06-10T03:22:21.247" Score="1" Body="&lt;p&gt;As a pilot of a recreational aircraft (very small aircraft) I have become accustom to the feel of the aircraft in a stall. When the aircraft stalls, it drops suddenly. This is the same feeling as being in a rollercoaster that has just gone over the top and begun to fall.&lt;br&gt;&#xA;My instinctive reaction in this case is to push the nose down. As soon as I have recovered from the disorientation of the stall (or turbulence which can cause the aircraft to drop momentarily), I can make better decisions.&lt;br&gt;&#xA;I am fairly sure (without any research) that a large aircraft would not have this characterisic, and as such, the pilots would not develop an instinct for this.&lt;/p&gt;&#xA;" OwnerUserId="8804" LastActivityDate="2015-06-10T03:22:21.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15619" PostTypeId="2" ParentId="15575" CreationDate="2015-06-10T04:08:24.133" Score="5" Body="&lt;p&gt;How unfortunate it is called &quot;stall training&quot; because I have never taught any of my students how to stall an aircraft!  I teach them to recognize the impending stall and how to fix it before the stall happens.  I show them a full stall and teach them how to recover.  It should be renamed &quot;stall recovery training&quot;  I try to surprise train also, during slow flight I keep stating they can fly slower and slower, I keep pushing to get them to fly slower....suddenly the plane drops out of the sky in an unexpected stall and they usually freeze for a couple of seconds then they recover.  Or during unusual attitude I will turn the controls over just as the plane stalls.  Point is, I focus more on recognition and recovery, than the stall itself.&lt;/p&gt;&#xA;" OwnerUserId="8806" LastActivityDate="2015-06-10T04:08:24.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15620" PostTypeId="2" ParentId="15600" CreationDate="2015-06-10T05:03:44.613" Score="6" Body="&lt;p&gt;In the Eighties and Nineties there was a concerted effort to reduce the nuclear arsenal on both sides of the Cold War. This resulted in a load of B-52s being dumped in the desert and being partly dismantled - wings cut off, etc. These aircraft had to remain there so that the Russians could verify by satellite that the US was adhering to its side of the relevant treaty. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/HVwAu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;B-52s chopped&quot; by federal photographer - AMARC. Licensed under Public Domain via Wikipedia&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia covers the &lt;a href=&quot;http://en.wikipedia.org/wiki/START_I&quot; rel=&quot;noreferrer&quot;&gt;START treaty&lt;/a&gt; and includes images of these bombers. I imagine the Russians had similar arrangements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USAF could still cannibalise these machines to keep other B-52s airworthy, but attempting to buy one is likely to be, shall we say, suspicious.&lt;/p&gt;&#xA;" OwnerDisplayName="user8807" LastActivityDate="2015-06-10T05:03:44.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15621" PostTypeId="2" ParentId="15600" CreationDate="2015-06-10T06:50:04.703" Score="1" Body="&lt;p&gt;To put stuff into context, It was rumored (so I cannot guarantee the authenticity of this claim) that my university declined an engine to go with their old donated F16 out of security concerns, i.e. that some people and organizations would have become a little too 'interested'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact remains that many countries have any old American aircraft, yet are not (or no longer) 'allies' of the United States. They have a correspondingly difficult time to get hold of parts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Iran has F4, F5, F14s and C130s.&lt;/li&gt;&#xA;&lt;li&gt;Venezuela has F16s&lt;/li&gt;&#xA;&lt;li&gt;Pakistan has F16s.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Needless to say, none of these could really be considered 'allies'.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a seemingly irrelevant piece of metal (that you say would like to use for furniture or what not else) could have value to somebody who has difficulties or limitations in acquiring spare parts for their jets. &lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-06-10T06:50:04.703" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15622" PostTypeId="2" ParentId="15617" CreationDate="2015-06-10T08:25:42.210" Score="4" Body="&lt;p&gt;To the best of my knowledge, you do not require any certification to fix a runway/taxiway, and anyone with a proper equipment can do that. But to facilitate the process, the FAA has published a few checklists which have to be filled while doing this repair job. These checklists can be found &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/runway_construction/&quot;&gt;Here&lt;/a&gt;. FAA also provides assistance in guiding the construction jobs and identifying risks, the link to which is in the same website as mentioned above.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-10T08:25:42.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15623" PostTypeId="2" ParentId="15604" CreationDate="2015-06-10T08:40:14.033" Score="5" Body="&lt;p&gt;I found a resource specifically for Emirates, so I'll try to explain it with respect to Emirates, though various other Airlines would use more or less the same principle.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Emirates uses Panasonic Avionics IFE (In Flight Entertainment) system.&#xA;  They have the 3000i which is older generation of IFE system on older&#xA;  aircrafts and the latest version ex2 on new aircrafts. Media licensing&#xA;  is managed, I believe, by the IFE provider via links to the major&#xA;  studios. In this tie up, the media is encrypted and stored in portable&#xA;  media loaders for the airline to update on the aircrafts. As the media&#xA;  is encrypted so the studio doesn't have much objection in giving away&#xA;  the rights to air the movies on board rather quickly.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Portable media loaders use optical connection for faster data transfer to&#xA;  minimize the loading time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Main Aircraft Interface (AI) Server is nothing but a small&#xA;  computer which is generally called a LRU (Line Replaceable Unit) a&#xA;  small box which controls the entire IFE system of the aircraft the&#xA;  back end software can either be windows 95 or Linux depending on the&#xA;  type of system. 3000i uses windows. The movies are stored on other&#xA;  LRUs which are generally an array of Digital Data Servers or Media&#xA;  Servers (MS) or in lay mans terms Hard Drives! These are connected in&#xA;  a LAN network and ethernet IP addressing is used in the entire&#xA;  aircraft system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The data is distributed over Optical fiber in first phase and over&#xA;  normal ethernet network to the specific seats. The interface is done&#xA;  via Ethernet Switches which intelligently routes the data from the&#xA;  Media server to the Area Distribution box to the Seat Electronic box&#xA;  and finally to the Smart Display.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Using a central dedicated computer instead of individual computers on different seats is preferred as it is less costly. Also, the IFE is connected to Aircraft's Main &lt;em&gt;IFE&lt;/em&gt; cpomputer, and not the Aircraft's main computer, so by hacking it all you get is the files (IFE files), not the aircraft data, though the moving map system data might be first dumped into the IFE system from the Airplane's main computer&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-10T08:40:14.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15626" PostTypeId="2" ParentId="15539" CreationDate="2015-06-10T09:35:21.907" Score="0" Body="&lt;p&gt;In aviation altitude usually refers to distance between MSL(mean see level) and aircraft and height to the distance between aircraft and terrain. Barometric altimeters are used to measure altitude. But they have a lot of errors. To get correct altitude you have to set correct pressure and correct for other errors like temperature. Temperature corrections are only used if it's cold and you are in danger of hitting obstacles. So you will never have exact altitude not to speak about height because altimeter knows nothing about terrain. Transponder just reports number based on standard pressure setting. So this number can differ by hundred of meters from real altitude. &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-06-10T09:35:21.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15627" PostTypeId="1" CreationDate="2015-06-10T09:54:21.273" Score="3" ViewCount="175" Body="&lt;p&gt;Which system is in place which gets data from all the flights on a terminal and display them every where like Airport Screens, Websites, different Apps etc?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="8547" LastEditDate="2015-06-10T10:27:52.170" LastActivityDate="2015-06-10T10:30:08.740" Title="What system populates the Flight Stats?" Tags="&lt;airline-operations&gt;&lt;flight-stat&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15628" PostTypeId="2" ParentId="15627" CreationDate="2015-06-10T10:14:54.073" Score="2" Body="&lt;p&gt;The same system which populates all the data on displays in a Railway Terminal.&lt;/p&gt;&#xA;&lt;p&gt;For a standalone airport, this data can be mined from ATC of that airport (Which has all the data regarding incoming/outbound flights ).&lt;/p&gt;&#xA;&lt;p&gt;On an International scale, the data has to be mined from various different agencies. According to a data provider &lt;a href=&quot;http://www.flightstats.com/go/FlightStatus/flightStatusByAirport.do#1&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightStats&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;It gets data from:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Complete, accurate data is the cornerstone of our business and what&#xA;sets us apart from competitive solutions:&lt;/p&gt;&#xA;&lt;p&gt;Geographic Coverage - FlightStats provides definitive information for approximately 99.5% of U.S. flights, and better than 86% of&#xA;flights worldwide.&lt;/p&gt;&#xA;&lt;p&gt;Completeness - FlightStats queries multiple sources to create a record for each flight enabling us to offer a broader range of&#xA;information (for example, gate information).&lt;/p&gt;&#xA;&lt;p&gt;Accuracy - We have invested heavily in the areas of parsing, interpretation and error checking and developed the logic that enables&#xA;handling of difficult issues such as cancellations, diversions and&#xA;changing schedules.&lt;/p&gt;&#xA;&lt;p&gt;Codeshare Support - Our codeshare logic enables us to deliver flight information for both the operating and the marketing carriers,&#xA;filling what is often a major gap in coverage.&lt;/p&gt;&#xA;&lt;p&gt;Real-time data sources include:&lt;/p&gt;&#xA;&lt;pre&gt;&lt;code&gt;FAA ASDI Data Feed&#xA;European Data Feed&#xA;GDS (Sabre, Amadeus, Apollo, Galileo)&#xA;Direct Airport / Airline Data Feeds&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;p&gt;Batch data sources include:&lt;/p&gt;&#xA;&lt;pre&gt;&lt;code&gt;Innovata Schedules&#xA;TSA Security Wait Times&#xA;Security Information&#xA;Health Information&#xA;Consular Information&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For the system which gets all this data from various different sources, its the central computer database of the airport, which gets data from ATC and the a fore mentioned sources, and this database is accessed by many other end users, including the Screens in the airport&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-10T10:30:08.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15629" PostTypeId="1" AcceptedAnswerId="15647" CreationDate="2015-06-10T10:23:57.427" Score="5" ViewCount="3674" Body="&lt;p&gt;For long range, wide body planes A380 and B777, what is the power generated by RAT (Ram Air Turbine)? And which all are the systems which the RAT drives?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-04T11:14:58.567" LastActivityDate="2016-07-04T11:14:58.567" Title="How much power is generated by a Ram Air Turbine (RAT)?" Tags="&lt;emergency&gt;&lt;electrical-system&gt;&lt;rat&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15630" PostTypeId="5" CreationDate="2015-06-10T10:25:23.640" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-10T10:25:23.640" LastActivityDate="2015-06-10T10:25:23.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15631" PostTypeId="4" CreationDate="2015-06-10T10:25:23.640" Score="0" Body="A ram air turbine (commonly known by the acronym RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-10T13:19:53.700" LastActivityDate="2015-06-10T13:19:53.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15632" PostTypeId="1" CreationDate="2015-06-10T10:33:13.410" Score="10" ViewCount="3468" Body="&lt;p&gt;Bleed air is using by airplanes for various purposes including deicing and also to feed air conditioning units that maintain temperature inside cabin. What kind of filters does bleed air pass through before reaching the cabin?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="39" LastEditDate="2015-07-02T16:52:51.960" LastActivityDate="2019-01-07T10:23:49.443" Title="What kind of filters are being used to filter the bleed air?" Tags="&lt;bleed-air&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15633" PostTypeId="1" AcceptedAnswerId="15655" CreationDate="2015-06-10T10:49:03.023" Score="3" ViewCount="295" Body="&lt;p&gt;How are &lt;a href=&quot;https://en.wikipedia.org/wiki/Fenestron&quot; rel=&quot;nofollow&quot;&gt;Fenestrons&lt;/a&gt; (or fantails) able to reduce the tip vortex losses in a helicopter?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-06-11T19:25:24.687" LastActivityDate="2015-06-11T19:25:24.687" Title="How does a Fenestron remove or reduce the tip vortex losses in a helicopter?" Tags="&lt;fenestron&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2015-06-16T12:56:20.130" ContentLicense="CC BY-SA 3.0" />
  <row Id="15634" PostTypeId="1" AcceptedAnswerId="15656" CreationDate="2015-06-10T11:23:58.583" Score="3" ViewCount="732" Body="&lt;p&gt;In many helicopters, they say they have reduced the vibrations significantly, but how is this isolation being achieved?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="14897" LastEditDate="2018-03-21T21:42:16.647" LastActivityDate="2018-03-21T21:42:16.647" Title="How is vibration isolation achieved in helicopters?" Tags="&lt;helicopter&gt;&lt;vibration&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15635" PostTypeId="2" ParentId="15632" CreationDate="2015-06-10T11:25:28.460" Score="3" Body="&lt;p&gt;Bleed Air is filtered using air filters. Various companies offer a lot of air filters, but High-efficiency particulate arrestance (HEPA) is a fairly common filter used to filter bleed air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its working is as under:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;HEPA filters are composed of a mat of randomly arranged fibres. The&#xA;  fibres are typically composed of fiberglass and possess diameters&#xA;  between 0.5 and 2.0 micrometers. Key factors affecting function are&#xA;  fibre diameter, filter thickness, and face velocity. The air space&#xA;  between HEPA filter fibres is much greater than 0.3 μm. The common&#xA;  assumption that a HEPA filter acts like a sieve where particles&#xA;  smaller than the largest opening can pass through is incorrect. Unlike&#xA;  membrane filters at this pore size, where particles as wide as the&#xA;  largest opening or distance between fibres cannot pass in between them&#xA;  at all, HEPA filters are designed to target much smaller pollutants&#xA;  and particles. These particles are trapped (they stick to a fibre)&#xA;  through a combination of the following three mechanisms:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Interception, where particles following a line of flow in the air stream come within one radius of a fibre and adhere to it.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Impaction, where larger particles are unable to avoid fibres by following the curving contours of the air stream and are forced to&#xA;  embed in one of them directly; this effect increases with diminishing&#xA;  fibre separation and higher air flow velocity.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Diffusion, an enhancing mechanism that is a result of the collision with gas molecules by the smallest particles, especially&#xA;  those below 0.1 µm in diameter, which are thereby impeded and delayed&#xA;  in their path through the filter; this behaviour is similar to&#xA;  Brownian motion and raises the probability that a particle will be&#xA;  stopped by either of the two mechanisms above; it becomes dominant at&#xA;  lower air flow velocities.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;Diffusion predominates below the 0.1 μm diameter particle size.&#xA;  Impaction and interception predominate above 0.4 μm. In between, near&#xA;  the most penetrating particle size (MPPS) 0.3 μm, both diffusion and&#xA;  interception are comparatively inefficient. Because this is the&#xA;  weakest point in the filter's performance, the HEPA specifications use&#xA;  the retention of these particles to classify the filter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Lastly, it is important to note that HEPA filters are designed to&#xA;  arrest very fine particles effectively, but they do not filter out&#xA;  gasses and odor molecules. Circumstances requiring filtration of&#xA;  volatile organic compounds, chemical vapors, cigarette, pet, and/or&#xA;  flatulence odors call for the use of an activated carbon (charcoal)&#xA;  filter instead of or in addition to a HEPA filter. (ZAND)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;HEPA actually looks like this :&lt;img src=&quot;https://i.stack.imgur.com/XiXt1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specifications of HEPA are as under:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;HEPA filters, as defined by the DOE standard adopted by most American&#xA;  industries, remove at least 99.97% of airborne particles 0.3&#xA;  micrometers (µm) in diameter. The filter's minimal resistance to&#xA;  airflow, or pressure drop, is usually specified around 300 Pa at its&#xA;  nominal flow rate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The specification usually used in the European Union is the European&#xA;  Norm EN 1822:2009. It defines several classes of HEPA filters by their&#xA;  retention at the given most penetrating particle size (MPPS):&#xA;  particle size (MPPS):&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;code&gt;HEPA class    retention (total)   retention (local)&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;E10          &amp;gt;85%                 ---&#xA;&#xA;E11          &amp;gt;95%                 ---&#xA;&#xA;E12          &amp;gt;99.5%               ---&#xA;&#xA;H13          &amp;gt;99.95%            &amp;gt;99.75%&#xA;&#xA;H14          &amp;gt;99.995%           &amp;gt;99.975%&#xA;&#xA;U15          &amp;gt;99.9995%          &amp;gt;99.9975%&#xA;&#xA;U16          &amp;gt;99.99995%         &amp;gt;99.99975%&#xA;&#xA;U17          &amp;gt;99.999995%        &amp;gt;99.9999%&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;  &#xA;  &lt;p&gt;The original HEPA filter was designed in the 1940s and was used in the&#xA;  Manhattan Project to prevent the spread of airborne radioactive&#xA;  contaminants. It was commercialized in the 1950s, and the original&#xA;  term became a registered trademark and a generic term for highly&#xA;  efficient filters. Over the decades filters have evolved to satisfy&#xA;  the higher and higher demands for air quality in various high&#xA;  technology industries, such as aerospace, pharmaceutical processing,&#xA;  hospitals, health care, nuclear fuels, nuclear power, and electronic&#xA;  microcircuitry (computer chips).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Today, a HEPA filter rating is applicable to any highly efficient air&#xA;  filter that can attain the same filter efficiency performance&#xA;  standards as a minimum and is equivalent to the more recent NIOSH N100&#xA;  rating for respirator filters. The United States Department of Energy&#xA;  (DOE) has specific requirements for HEPA filters in DOE regulated&#xA;  applications. In addition, companies have begun using a marketing term&#xA;  known as &quot;True HEPA&quot; to give consumers assurance that their air&#xA;  filters are indeed certified to meet the HEPA standard.[4]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Products that claim to be &quot;HEPA-type&quot;, &quot;HEPA-like&quot;, &quot;HEPA-style&quot; or&#xA;  &quot;99% HEPA&quot; do not satisfy these requirements and may not have been&#xA;  tested in independent laboratories. Some of these sub-par quality&#xA;  filters may come reasonably close to HEPA filtration, while others&#xA;  will fall significantly short, making them truly inferior.[5]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is the Wikipedia &lt;a href=&quot;http://en.wikipedia.org/wiki/HEPA&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-10T12:21:29.120" LastActivityDate="2015-06-10T12:21:29.120" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15636" PostTypeId="1" CreationDate="2015-06-10T11:29:15.297" Score="1" ViewCount="311" Body="&lt;p&gt;Do modern passenger aircafts like 747/787/A320/A380 have some sub-system or sensors which are plug and play that might include some kind of sensors or radars which comes as optional and can be used plug-play as and when needed as per the requirement?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5694" LastEditDate="2015-06-10T11:49:52.493" LastActivityDate="2015-06-11T14:46:09.147" Title="Do modern aircrafts like 747/787/A320/A380 have some Plug and Play subsystems/sensors?" Tags="&lt;aircraft-subsystem&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15637" PostTypeId="1" AcceptedAnswerId="16272" CreationDate="2015-06-10T11:41:54.570" Score="7" ViewCount="2834" Body="&lt;p&gt;Leading Edge Root Extensions were first used in Northrop F-5A/B Freedom Fighter, which first flew in 1959. After that, many fighter air-crafts have used it, some of which are mentioned after the question. The reason behind using such extension is delay of stall at very high angles of attack. How does the use of Leading Edge Root Extension help in increasing stall angle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Northrop F-5A/B Freedom Fighter&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0M4IB.jpg&quot; alt=&quot;Northrop F-5 Tiger II, source unknown&quot;&gt;&#xA;&lt;sup&gt;author unknown, public domain (&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Northrop_F-5E_(Tail_No._01557)_061006-F-1234S-073.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sukhoi Su-27&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oN9y8.jpg&quot; alt=&quot;Sukhoi Su-27SKM, photo by Dmitriy Pichugin&quot;&gt;&#xA;&lt;sup&gt;photo by Dmitriy Pichugin, GFDL 1.2 (&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Sukhoi_Su-27SKM_at_MAKS-2005_airshow.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;McDonnell Douglas F/A-18 Hornet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TZC5C.jpg&quot; alt=&quot;F/A-18C Hornet (United States Marine Corps), photo by LCPL JOHN MCGARITY, USMC, public domain&quot;&gt;&#xA;&lt;sup&gt;photo by LCPL John McGarity, USMC, public domain (&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:USMC_FA-18_Hornet.JPEG&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-04T11:32:13.037" LastActivityDate="2017-06-30T05:39:43.347" Title="How does the use of Leading Edge Root Extension help in increasing stall angle?" Tags="&lt;stall&gt;&lt;high-lift-device&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15638" PostTypeId="5" CreationDate="2015-06-10T11:44:35.767" Score="0" Body="&lt;p&gt;&lt;em&gt;High-lift devices&lt;/em&gt; are parts of an aircraft used to increase the amount of &lt;a href=&quot;/questions/tagged/lift&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;lift&amp;#39;&quot; rel=&quot;tag&quot;&gt;lift&lt;/a&gt; it can generate, and thereby increase the aircraft's payload capacity and/or decrease its &lt;a href=&quot;/questions/tagged/takeoff&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;takeoff&amp;#39;&quot; rel=&quot;tag&quot;&gt;takeoff&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/landing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing&lt;/a&gt; speeds.  Most high-lift devices are placed on either the leading or the trailing edges of the wings, but high-lift devices in other places also exist:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Leading-edge devices&lt;/strong&gt; are, as the name indicates, located on the wing's leading edge.  Although they do directly increase the wing's lift by a small amount, their main benefit is to increase the &lt;a href=&quot;/questions/tagged/angle-of-attack&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;angle-of-attack&amp;#39;&quot; rel=&quot;tag&quot;&gt;angle-of-attack&lt;/a&gt; at which the wing experiences a &lt;a href=&quot;/questions/tagged/stall&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stall&amp;#39;&quot; rel=&quot;tag&quot;&gt;stall&lt;/a&gt;, allowing the wing to be rotated to a higher angle of attack (and, thus, be made to produce more lift) before it stalls.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Droops&lt;/em&gt; are hinged sections of the wing's leading edge that can be rotated downwards to increase the wing's camber (the curvature of its upper surface).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/slats&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;slats&amp;#39;&quot; rel=&quot;tag&quot;&gt;slats&lt;/a&gt; are movable sections of the leading edge which slide forwards and downwards, simultaneously increasing the wing's camber and opening up a slot in the wing just behind the leading edge.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Slots&lt;/em&gt; are similar to slats, but, instead of extending and retracting, they are fixed in the extended position, leaving the wing with a permanent slot (hence the name) immediately behind its leading edge.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Krueger flaps&lt;/em&gt;, despite their name, are more akin to other leading-edge devices than to trailing-edge flaps; they consist of panels under the wing's leading edge, hinged at their front end, which swing out from under the wing to increase the camber of the wing's leading edge.  This is much simpler to show than it is to describe; a diagram is probably in order:&lt;a href=&quot;https://i.stack.imgur.com/vsNml.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vsNml.png&quot; alt=&quot;how ye olde krueger flap works&quot;&gt;&lt;/a&gt;&#xA;(Image by Stahlkocher and HDP &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Krueger-Flap.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;at Wikimedia Commons&lt;/a&gt;.)&lt;/li&gt;&#xA;&lt;li&gt;A &lt;em&gt;leading-edge root extension&lt;/em&gt; (LERX) is a long, narrow, triangular panel extending forward along the fuselage from the leading edge of the wing root, creating a &lt;a href=&quot;/questions/tagged/vortex&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vortex&amp;#39;&quot; rel=&quot;tag&quot;&gt;vortex&lt;/a&gt; over the upper surface of the wing and preventing the airflow over the wing from separating from it (the wing).&lt;/li&gt;&#xA;&lt;li&gt;A &lt;em&gt;cuff&lt;/em&gt; or &lt;em&gt;dogtooth&lt;/em&gt; is a sharp, zigzag discontinuity in the wing's leading edge, which produces vortices that keep a stall from progressing outboard beyond the discontinuity.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Trailing-edge devices&lt;/strong&gt; are located, surprise surprise, on the wing's trailing edge.  They work by directly increasing the amount of lift produced by the wing at a given angle of attack.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The major trailing-edge devices of note are &lt;a href=&quot;/questions/tagged/flaps&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flaps&amp;#39;&quot; rel=&quot;tag&quot;&gt;flaps&lt;/a&gt;, a large family of devices which generally increase lift by increasing the wing's area, its camber, or both.&lt;/li&gt;&#xA;&lt;li&gt;The flap function can also be combined with an aircraft's &lt;a href=&quot;/questions/tagged/ailerons&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;ailerons&amp;#39;&quot; rel=&quot;tag&quot;&gt;ailerons&lt;/a&gt; as a &lt;a href=&quot;/questions/tagged/flaperon&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;flaperon&amp;#39;&quot; rel=&quot;tag&quot;&gt;flaperon&lt;/a&gt;, which allows a single set of surfaces to serve double duty for lift enhancement and roll control (instead of requiring two dedicated sets, one for each function), reducing weight.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;High-lift devices not attached to either the leading or trailing edges include:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Boundary-layer control systems&lt;/em&gt; (BLCSs) blow high-energy air (usually from the engine(s)) into the thin &quot;boundary layer&quot; next to the surface of the wing, reenergising this layer and making it more resistant to separating from the wing at high angles of attack.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/vortex-generators&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vortex-generators&amp;#39;&quot; rel=&quot;tag&quot;&gt;vortex-generators&lt;/a&gt; cause the airflow along the wing's upper surface to curl up into narrow vortices which stick to the wing's surface more readily than non-vortex air, allowing this airflow to remain attached to the wing at higher angles of attack.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Nose strakes&lt;/em&gt; are like LERXs, but are mounted ahead of the wing instead of being attached to it.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For more information, see the Wikipedia pages on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/High-lift_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;High-lift devices&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flap_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flaps&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flaperon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flaperons&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Leading-edge_slat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Slats&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Droop_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Droops&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Krueger_flap&quot; rel=&quot;nofollow noreferrer&quot;&gt;Krueger flaps&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Leading-edge_extension&quot; rel=&quot;nofollow noreferrer&quot;&gt;Leading-edge extensions&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boundary_layer_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boundary-layer control&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_generator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vortex generators&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-08-31T07:08:22.813" LastActivityDate="2019-08-31T07:08:22.813" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15639" PostTypeId="4" CreationDate="2015-06-10T11:44:35.767" Score="0" Body="Use for high-lift devices such as flaps, slats, slots, etc." OwnerUserId="8547" LastEditorUserId="14897" LastEditDate="2021-04-28T03:52:42.417" LastActivityDate="2021-04-28T03:52:42.417" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15640" PostTypeId="1" AcceptedAnswerId="15644" CreationDate="2015-06-10T11:47:03.760" Score="6" ViewCount="803" Body="&lt;p&gt;I have seen in many helicopters pop-out floats installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they the optional, or do they come pre-installed with every helicopter?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="3386" LastEditDate="2015-06-10T13:27:26.937" LastActivityDate="2015-06-10T13:29:10.420" Title="Can pop-out floats be installed post-manufacture on all helicopters?" Tags="&lt;helicopter&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15641" PostTypeId="2" ParentId="15636" CreationDate="2015-06-10T12:23:14.590" Score="7" Body="&lt;p&gt;It wouldn't make much sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By definition &quot;plug and play&quot; would means that the avionics &lt;em&gt;automatically and silently&lt;/em&gt; adapts to whether whether the optional device is present or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would mean that if the device is &lt;em&gt;physically&lt;/em&gt; fitted, but &lt;em&gt;not in contact&lt;/em&gt; with the main avionics -- say, a wire might have broken or shaken loose recently -- then the cockpit instrumentation would look exactly as if it had never been there. This is not desirable: when something the pilot &lt;em&gt;thinks&lt;/em&gt; will be available for the flight isn't actually available you want to tell him explicitly so he can decide whether the problem needs to be planned around or reacted to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are limits to how much the plane can &lt;em&gt;itself&lt;/em&gt; verify that it is whole and in working order -- that's why there are preflight checklists. But to spend engineering effort &lt;em&gt;specifically&lt;/em&gt; on allowing it to fail &lt;em&gt;silently&lt;/em&gt; when communication with one of the sensors is lost, that would be counterproductive.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-06-10T12:23:14.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15642" PostTypeId="2" ParentId="13039" CreationDate="2015-06-10T12:43:05.560" Score="2" Body="&lt;p&gt;First off, auto-rotation is a general term for all helicopters and the process varies between different air-crafts and the cause of the auto-rotation. For example, in auto-rotation due to loss of tail rotor thrust you can (and should) descend with some collective power and reduce descent rate. Also, in such auto-rotation there is also a mandatory step 2.5 - cut the power. Otherwise, the craft will rotate out of control in the quick stop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also various helicopter types behave differently while auto-rotating such as bigger helicopters start flaring at least 125 feet above ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the steps described - I'll agree that they break down nicely the process into other familiar processes, even though obviously not entirely accurate. I think the main difference is that flaring from altitude in a 1500-3000 ft/second descend and approaching a quick stop usually with speed forward rather than downward - require significantly different flight technique and practice. &lt;/p&gt;&#xA;" OwnerUserId="8813" LastActivityDate="2015-06-10T12:43:05.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15643" PostTypeId="1" AcceptedAnswerId="15646" CreationDate="2015-06-10T13:10:03.923" Score="7" ViewCount="2220" Body="&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Droop_(aeronautics)&quot;&gt;Droops&lt;/a&gt; are deployed on the leading edge of a wing of an aircraft, and they work by changing the camber of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do they help in delaying stall?&lt;/p&gt;&#xA;" OwnerUserId="8814" LastEditorUserId="62" LastEditDate="2015-06-13T19:58:41.393" LastActivityDate="2020-03-18T06:14:00.567" Title="How do droops help to avoid stalls?" Tags="&lt;stall&gt;&lt;lift&gt;&lt;high-lift-device&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15644" PostTypeId="2" ParentId="15640" CreationDate="2015-06-10T13:29:10.420" Score="2" Body="&lt;p&gt;Pop out floats can be installed easily on any helicopter with Tubular landing skid type landing gear. Its essentially an auto-inflatable tube attached to the landing gear. Have a look at this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7CkKt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-10T13:29:10.420" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15645" PostTypeId="2" ParentId="15636" CreationDate="2015-06-10T13:34:03.283" Score="4" Body="&lt;p&gt;I will answer this from a US FAA regulations stand point, but you really have 2 questions here &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do modern passenger aircrafts like 747/787/A320/A380 have some sub-system&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer to this in certain ways of looking at it is yes. Modern glass cockpit style aircraft use &lt;a href=&quot;http://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow&quot;&gt;ARINC Data Busses&lt;/a&gt; to transfer the data from the sensors to the main flight computers. Depending on how you define subsystem one could argue that this data bus is in a way a sub system. I am not positive on how to actually set one up and if the devices simply plug into it and self registers or need to be manually installed and programed some how but there are sub systems on large planes that share resources. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...plug and play that might include some kind of sensors or radars which comes as &lt;strong&gt;optional&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are lots of &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch10.pdf&quot; rel=&quot;nofollow&quot;&gt;requirements&lt;/a&gt; around aircraft instruments and the way I understand them there really is not a lot of &quot;optional&quot; stuff. There are with out a doubt redundant things and backup systems. With this in mind there are some systems like auto pilot that if it was not working the plane is still more than capable of flying. But as for critical flight instruments even if they are plug and play you don't really have the choice of not having them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a bit of a side not Aspen Avionics has recently released an &lt;a href=&quot;http://www.aspenavionics.com/aoa&quot; rel=&quot;nofollow&quot;&gt;all software AOA indicator&lt;/a&gt; that runs in their glass cockpit system. This was traditionally done with a mechanical device like &lt;a href=&quot;http://www.aircraftspruce.com/catalog/inpages/garmin10-05793.php&quot; rel=&quot;nofollow&quot;&gt;this one that Garmin makes&lt;/a&gt;. Im not sure I would call the aspen unit plug and play as there is no physical device to plug in but it is a software plug in situation for their units and worth the mention.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-11T02:34:24.680" LastActivityDate="2015-06-11T02:34:24.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15646" PostTypeId="2" ParentId="15643" CreationDate="2015-06-10T13:52:41.943" Score="11" Body="&lt;p&gt;Similar to a leading edge flap, fixed in the extended position with no gaps: The nose is lowered, so at high angles of attack the flow still has its stagnation point at the round nose where on an un-drooped nose it would had slipped below the nose section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/45BOV.png&quot; alt=&quot;Cut through a wing with leading edge flap&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This reduces the suction peak near the nose of the upper surface pressure distribution and consequently makes recompression towards the trailing edge much easier. This helps to delay flow separation and to achieve higher angles of attack and lift. If an aircraft had a roll instability at high angle of attack, adding a drooped nose on the outer wing will cure it of misbehaving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downside is that now at low angles of attack a suction peak will form on the bottom side and might cause local flow separation. This increases the viscous drag just when this drag component dominates overall drag. Consequently, aircraft which had been modified with a drooped nose do not reach their old top speed anymore.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-25T08:20:08.480" LastActivityDate="2015-06-25T08:20:08.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15647" PostTypeId="2" ParentId="15629" CreationDate="2015-06-10T14:17:51.137" Score="9" Body="&lt;p&gt;According to the Flight Crew Operations Manual of the Boeing 777:&lt;/p&gt;&#xA;&lt;h2&gt;Hydraulics&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The RAT, when deployed, provides hydraulic power only to the &lt;strong&gt;primary&lt;/strong&gt;&#xA;flight control components connected to the center hydraulic system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OzUaz.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Which leaves out:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Nose gear&lt;/li&gt;&#xA;&lt;li&gt;Main gear&lt;/li&gt;&#xA;&lt;li&gt;Steering&lt;/li&gt;&#xA;&lt;li&gt;Brakes&lt;/li&gt;&#xA;&lt;li&gt;Flaps&lt;/li&gt;&#xA;&lt;li&gt;Thrust reversers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h2&gt;Electric&lt;/h2&gt;&#xA;&lt;p&gt;The RAT powers both C1 TRU and C2 TRU, which powers the captain's and first officer's flight instruments, respectively.&lt;/p&gt;&#xA;&lt;p&gt;The RAT can supply electrical and hydraulic power simultaneously. However, if the RAT is unable to maintain its RPM, the electrical load is shed and provided by the main battery, until RPM is satisfactory.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-10T14:17:51.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15648" PostTypeId="2" ParentId="8172" CreationDate="2015-06-10T15:07:05.790" Score="6" Body="&lt;p&gt;The two weights are not directly related: in theory max take-off COULD be less than max landing, but that would show an issue with the design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take-off is determined by available field length in effect, and thus the engine thrust needed to get the plane airborne (before you run out of field). And in fact, you need a long enough field so that at V1 you can stop and and not fall off the end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the designer has to have enough thrust to goose it into the air fast enough, with enough fuel to fly to where they need to get to. More engines is more mass, more expense, and more fuel to run them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing is not determined by engine thrust, in fact engine size works against you a bit because bigger engines are heavier. Landing relies only on drag and brakes. In fact you CAN land with max take-off weight, but that's an extreme, and you might burn your brakes/blow tires. Max landing weight also has to take into account bad weather, which increases required runway length. Also has to take into account possibility you might not have full use of flaps for drag, so need combination of longer runway, and enough braking capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial jets are all about economics and the trade-offs made in the design. You don't NEED to have max landing weight the same as max take-off, except in case of an emergency right after takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you download PIANO (the free/trial version) you can select various weights for take-off and landing. See what it does to the landing field lengths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember also that there is an existing set of airports that the designers want their planes to be able to take-off from, and land at. Also that the routes they want to fly have certain distances, needing enough fuel to get there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you increase take off weight, you need more lift, and more thrust. And you have to do it in the available runway length. When you land, you can take advantage of that lift (since you got it from a bigger effective wing area) but you also need brakes. Brakes are heavy and cost money to build as well as maintain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take off weight will vary from low (just enough to get to a nearby airport) to the max: enough to get to the farthest one. Landing weight SHOULD ideally be the same: just the empty plane weight and the reserve. Anything more and something has gone wrong. So the designer aims for that, and builds enough safety into the system to allow a landing with max takeoff, but with the possibility of tires blowing, or at least having to wait until brakes cool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read an account of commercial planes flying into Kabul fully loaded with fuel for re-supply, and they had problems with hot brakes, blown tires etc. Commercial planes are not designed for that. True military tankers/freighters have more effective reverse thrust, and need to use it to land on short runways. And there is no concern for passenger safety for hard deceleration, nor for noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason commercial jets don't use reverse thrust more is because of noise (and emission) regulations. Otherwise you could land as heavy as you wanted: reverse thrust can give you up to 20%-30% of max thrust, and is effective at high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if you look at engine thrust, there is a huge difference between take-off max thrust and cruising. Once you are airborne, you don't need a very big engine. But you have to carry around all the extra bulk just to get into the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On short flights, one of the big issues is the time to cool the brakes. If you have a quick turn-around and not much time between your next landing then your brakes don't have much time to cool. In that case the max plane weights are not really the issue: you are not carrying much fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Airbus has data on how much reverse thrust each plane has. It is a function of N1 (fan speed) and air speed. See:&#xA;&lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Airbus_Takeoff_Safety_Training_Aid.html&quot; rel=&quot;noreferrer&quot;&gt;Airbus Takeoff Safety&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8815" LastEditorUserId="8815" LastEditDate="2015-06-10T18:50:55.313" LastActivityDate="2015-06-10T18:50:55.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15649" PostTypeId="2" ParentId="3709" CreationDate="2015-06-10T15:57:13.667" Score="-2" Body="&lt;p&gt;I was told to do the same thing.&#xA;They said that once the wheels started spinning (from take-off) they often didn't stop: the air flow tends to keep them going once they are spinning. It has a slight effect on bearing wear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just thought a 2nd reason now: when you land if they are already spinning, then when you land, they don't need anymore energy to get up to speed. But you'd rather they DID require some energy, that would help you slow down. Might be quite small though, I haven't calculated it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I doubt that it's a big deal either way.&lt;/p&gt;&#xA;" OwnerUserId="8815" LastActivityDate="2015-06-10T15:57:13.667" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15651" PostTypeId="2" ParentId="1106" CreationDate="2015-06-10T16:39:14.427" Score="5" Body="&lt;p&gt;Good question. With regards to mainstream commercial jets it might not do much and quite possibly be counter-productive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most (all?) Boeing and Airbus have about 95% of weight on the main landing gear (MLG), and thus the nose brake wouldn't be very heavily weighted, so not very effective. And for reasons of rotation, you don't want to load the nose very much, but rather have it pivot around the wings: where your lift is coming from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can then design the nose landing gear (NLG) to be quite light because it doesn't see a lot of load, nor take large braking reaction forces. And doesn't have any brakes/hydraulics etc. And the same with the fuselage strength: it's okay if the MLG take all the load: they are already in the &quot;beefy&quot; section of the plane, and there is no moment arm (torque) due to a big displacement from the centre-of-gravity (CG).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if you started to have large forces on the NLG, you have it a long way from the CG, and thus a big moment: you'd need to take that into account when you designed the fuselage, making it stronger, and thus heavier. At the moment with no lift on the front fuselage section, nor any forces from braking, you can make it pretty light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the MLG at the CG and also centre-of-lift from the wings (drag from spoilers) makes for a very stable system. Inherently stable too: the faster you go, the more drag from the wings, and thus more weight on the MLG, which they need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this will be the case for all planes with propulsion from the wings: regardless if props or jets. If you have a prop on the nose it's a bit different because you need to beef that up anyways, so you don't mind the braking loads from a nose-wheel. But I don't see a lot of advantages for it. You add all the extra weight of the hydraulics and brakes, plus the weight from making a much stranger assembly. More complexity, more to service and go wrong.&lt;/p&gt;&#xA;" OwnerUserId="8815" LastEditorUserId="65" LastEditDate="2015-06-10T17:59:01.650" LastActivityDate="2015-06-10T17:59:01.650" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15652" PostTypeId="2" ParentId="7802" CreationDate="2015-06-10T17:14:45.863" Score="5" Body="&lt;p&gt;The tires are getting hot because of the huge amount of kinetic energy absorbed by the brakes. They also get a bit of heat from being used (friction from landing) but that's not very big: you can design a tire to take that: after all, your car tires don't get that hot from being driven on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The brake assemblies act as heat sinks for the kinetic energy absorbed from braking: you have the whole brake assembly heating up to hundreds of degrees, even parts at 800-1,000 C. When you are moving, the air tends to stop the heat from going to the tires. And also to keep the brakes cooler by dissipating the heat. When you stop, the air isn't removing the heat, and radiant plus convective heat transfer from the brakes rapidly heat up the tires, causing the air pressure to increase. The plugs blow to prevent a uncontrolled burst. When you are moving there is no convective heat transfer, because of the air speed: as it heats it is replaced by fresh air. So there is only radiative heat transfer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why tire plugs blow only when the plane is stopped, and the brakes are not being heated anymore by braking, but are actually starting to cool. The heat has to go SOMEWHERE after all, and without a constant stream of air, the tires suffer. After all, they are right next to this massive source of heat energy, at high temperatures. Is like being under a grill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some brakes have fans to help the cooling when the plane is stopped, but it's not a standard fit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The landing gear is designed to prevent wheel burst (or fires) for enough time to allow the firemen to get there to either help cool the landing gear, or else extinguish any fires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cooling the brakes properly affects their longevity too: ideally you want them to cool slowly enough to even out any hot spots. Water cooling or even powerful fans can be problem because it can cool some parts too quickly: water mist is suggested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look on the Airbus site, they have some very interesting documents for each plane: Aircraft Characteristics Airport and Maintenance Planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/technical-data/aircraft-characteristics/&quot; rel=&quot;noreferrer&quot;&gt;Airbus Aircraft Characteristics Airport and Maintenance Planning&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a section that discusses what aircraft rescue and fire fighting should consider. One part discusses how they should deal with brake overheat and landing gear fire:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8OQdI.png&quot; alt=&quot;Hazard areas&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/1VVKg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8815" LastActivityDate="2015-06-10T17:14:45.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15653" PostTypeId="2" ParentId="14521" CreationDate="2015-06-10T18:37:26.260" Score="3" Body="&lt;p&gt;I'm not a commercial pilot but I've just been researching this for other reasons: to look at brake wear mechanisms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust reversers are normally supposed to be engaged on Airbus and Boeing commercial jets (that have them) when you are landing. Engaging them just means opening/moving the various flaps that divert the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However due to noise regulations, you normally are not allowed to actively use them: so you put the engines into idle thrust. However this has several advantages:&#xA; - the system is set up to allow a much bigger reverse thrust if you need it in a hurry&#xA; - you also don't have any positive thrust from the idle thrust since you have it reversed (which is not negligible, it varies from 3-6% of total max thrust)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAR/JAR landing calculations do not assume any credit for reverse thrusters, so in ideal conditions you shouldn't need them. But if you have a system malfunction or other problem (bad braking, poor flap control, slippery runway, short runway, very heavy plane etc) then they can help you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe most big commercial jet engines that have reverse thrust, can go up to 80%-90% of N1 (fan speed). That's because most work by opening up flaps that only divert the fan air output (which is about 80% of the thrust). These are for the &quot;translating cowl type&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus says that on the A330 with the GE CF6-80E1A2 engine, at 150kts and at 90% N1 you get 16,000 lb/engine reverse thrust (sea level). Which is 22% of max thrust. It drops to 8,000 lbs at 0 kts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reversers that open after the rear of the engine (&quot;target type&quot;) probably go to higher percentages, but I don't know how much. They are often on military planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect that because of the strict noise abatement rules now in place at most big airports, reverse thrusters are not much used in standard landings. And braking capacity has improved a lot. So if you cannot use them, then you don't have them in th design: which is why the Airbus 380 only has them on two engines. More for emergencies I'd guess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the efficiencies of wheel braking and air drag, the air drag works best at high air speeds: which is good, because this is where kinetic energy is the highest. As you slow down it becomes less effective, but then wheel braking can take over and control the deceleration at slower speeds, and where you might want to maneuver more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, you can see how much idle thrust occurs from Airbus and Boeing planes by looking at the charts they provide for Ground Towing Requirements. They tell you how much pullback is on the tow bar for the number of engines that are at idle. These charts are in the files they provide on the following (Section 5):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/technical-data/aircraft-characteristics/&quot; rel=&quot;nofollow&quot;&gt;Airbus Aircraft Characteristics - Airpot and Maintenance Planning&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/airports/plan_manuals.page&quot; rel=&quot;nofollow&quot;&gt;Boeing Aircraft Characteristics - Airpot and Maintenance Planning&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8815" LastActivityDate="2015-06-10T18:37:26.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15655" PostTypeId="2" ParentId="15633" CreationDate="2015-06-10T19:43:56.060" Score="4" Body="&lt;p&gt;There are basically two effects here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One is the ducted fan effect. Ducted fans are more efficient than open fans, specifically creating smaller vortices at the blade tips.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The other is the fact that the tail rotor of a helicopter is &lt;strong&gt;not&lt;/strong&gt; situated in an area with almost linear airflow along the rotor axis. It is also submitted to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A steady flow due to helicopter forward motion. This is coming from the &lt;strong&gt;side&lt;/strong&gt; of the rotor, so affects opposite rotor blades differently.&lt;/li&gt;&#xA;&lt;li&gt;A buffeting flow from the h/c main rotor. This is an unsteady flow, also coming laterally from the point of view of the tail rotor (actually, the top).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Fenestron tail-rotor ducts can be considered a fairing that reduces airflow across the rotor. The end result is that the rotor blades are in a much smoother flow that helps reduce unwanted turbulence. This is one of the reasons such rotors are quieter than regular open tail-rotors (the other being the fairing material absorbing some of the noise).&lt;/p&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="65" LastEditDate="2015-06-10T19:48:11.857" LastActivityDate="2015-06-10T19:48:11.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15656" PostTypeId="2" ParentId="15634" CreationDate="2015-06-10T19:55:03.407" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.slideshare.net/anyket/helicopter-vibration-reduction-techniques&quot;&gt;There are many techniques.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passive reduction techniques involve designing the powerplant, transmission, gearbox and particularly the rotor(s) to minimize vibration. Designers carefully arrange all the moving parts to be as closely balanced as possible. They can be mounted using flexible parts and springs to damp vibrations (the same principle behind the shock absorbers in an automobile). The sophistication of helicopter design has evolved over time as engineers learn more about the characteristics of helicopters and how mechanical parts behave. Computer-assisted design has also allowed for huge improvements here as moving parts can be simulated in great detail to optimize each individual part for minimum vibration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active systems work by using accelerometers to sense the vibration of the helicopter at certain points in real time. This data is then used to shake a reaction mass back and forth to &lt;em&gt;create&lt;/em&gt; vibration opposite to that of the rest of the helicopter. The two opposite vibrations cancel each other out. Effectively, the active system is using electrical power to dump all of the vibration energy in the helicopter into a small mass, so the helicopter stays still while the reaction mass in the active system shakes to absorb the energy. Such systems are already in common use in large transport helicopters and are becoming more prevalent in smaller helicopters as well.&lt;/p&gt;&#xA;" OwnerUserId="909" LastActivityDate="2015-06-10T19:55:03.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15658" PostTypeId="2" ParentId="1423" CreationDate="2015-06-10T20:41:05.067" Score="8" Body="&lt;p&gt;Are you talking the approach-to-land, or actual landing?   Keep in mind, when you flare, you are technically arresting a descent, so the VSI should not read much more/less than zero.&#xA;For a stable approach, 500-700 FPM on a 3 degree glide slope usually works out well for ILS approaches.  Keep in mind, all instrument approaches terminate visually, unless you are in a CAT III capable aircraft, which I do not fly.&lt;/p&gt;&#xA;" OwnerUserId="8817" LastActivityDate="2015-06-10T20:41:05.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15662" PostTypeId="1" AcceptedAnswerId="15666" CreationDate="2015-06-10T21:47:00.427" Score="12" ViewCount="1559" Body="&lt;p&gt;I am working on semi-realistic (let's just call it &quot;believable&quot;) flight simulation component set for a game engine. One of the topics that I tried to research but could not find reliable information on is the authority or effectiveness of flight control surfaces over AOA. I would prefer to see some graphs or some approximate math expression. I've found more or less enough information on other topics (e.g. lift coefficient over AOA) but I cannot really come up with reliable information (even just theory) regarding flight control surfaces. Gut feeling tells me that they would probably behave similar to wing, but on the other hand elevators should really not lose much authority even past stall AOA.&lt;/p&gt;&#xA;" OwnerUserId="8819" LastEditorUserId="1696" LastEditDate="2015-06-16T20:21:44.503" LastActivityDate="2018-06-09T09:05:46.307" Title="How does flight control surface authority change with AOA?" Tags="&lt;flight-controls&gt;&lt;stall&gt;&lt;angle-of-attack&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15663" PostTypeId="2" ParentId="13483" CreationDate="2015-06-10T21:53:00.490" Score="2" Body="&lt;p&gt;In &lt;a href=&quot;http://www.lawa.org/uploadedFiles/lax/noise/presentation/noiseRT_090513_Pratt%20and%20Whitney%20Presentation.pdf&quot; rel=&quot;nofollow&quot;&gt;this presentation&lt;/a&gt; from 2009 PW quote savings of 140 gallons on a 500 nm trip. I presume they are comparing it to current engine options such as the IAE V2500.&lt;/p&gt;&#xA;" OwnerUserId="8818" LastActivityDate="2015-06-10T21:53:00.490" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15664" PostTypeId="2" ParentId="7452" CreationDate="2015-06-10T22:31:02.657" Score="2" Body="&lt;p&gt;The landing without the use of the flaps is a good and safe method of landing (touching down) at a higher speed. This causes the nose to be at the same nose-'high' attitude at a higher speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In high crosswind situations, I would recommend landing at higher speeds too as this reduces effect of the crosswind component.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you have enough runway and don't land nosewheel first, I think it's safe to touch down at higher speed and actually safer in some situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approaching at higher speed at busy airports is also safer in my opinion. If you have to go around at a busy airport and don't know your way around exactly and have to attempt another approach and feed in between two airliners again, I'd go for a faster approach and landing if you're capable of doing that.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-10T22:31:02.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15665" PostTypeId="2" ParentId="15662" CreationDate="2015-06-10T22:40:15.907" Score="4" Body="&lt;p&gt;ALL flight control surfaces lose authority at lower speeds and/or in less dense air (heat/altitude). In most cases, this can be compensated somewhat by increasing the deflection until the max is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft with fly-by-wire can compensate for the 'sloppy' controls somewhat by doing the increase in deflection automatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although I can't help you with formulas or graphs, I can tell you that the reduction in effectiveness can be very significant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, by design, the elevator stalls much later than the main lifting surfaces for stability reasons and to have the ability to get out of a stall (naturally or by pilot input).&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-10T22:40:15.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15666" PostTypeId="2" ParentId="15662" CreationDate="2015-06-10T22:44:04.423" Score="12" Body="&lt;p&gt;Control authority is a function of the local dynamic pressure (the product of air density and speed squared), geometry (the product of control surface area and lever arm), local angle of attack $\alpha$, the angle of deflection $\eta$ and the relative flap chord. Generally, the control surface works fairly linearly in a range between $-15° &amp;lt; \eta &amp;lt; 15°$ for a relative flap chord of 25% rsp. $-25° &amp;lt; \eta &amp;lt; 25°$ for a relative flap chord of 15%. Interpolate for values in between. Note that flap effectiveness is proportional to the square root of the relative flap chord, such that a flap of 15% needs twice the deflection angle to effect the same control authority than a flap of 60% relative chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bigger deflection angles reduce flap authority, and here it becomes complicated, because local flow phenomena can make a big difference, up to control reversal. For a simple model you may just assume that control authority is cut in half for all deflections exceeding the limits mentioned above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all is only valid for moderate angles of attack, when forces change linearly with angle of attack changes. Once you approach the lift force limits of the particular control surface, authority suffers. Now it is important to know the local flow field: Elevators fly in the wake of the wing, which in effect reduces the angle of attack changes at the elevator compared to those at the wing. This means that most elevators still have a healthy lift margin when the wing starts to stall. But stall they will, eventually. To give you an idea how a wing performs over the first 180° of angle of attack, see the plot below. A plot for a control surface should look similarly. It is taken from &lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/9993623938&quot; rel=&quot;nofollow noreferrer&quot;&gt;a book which should exhaustively answer all your questions about control surface authority&lt;/a&gt;, be it subsonic or supersonic, for all conceivable configurations. It has been written by Sighard Hörner half a century ago and is still the best you will be able to find on this topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pkSpz.png&quot; alt=&quot;Plot of $c_L$ over 180° angle of attack from Hörner&amp;#39;s book&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an example of an airfoil's flap effectiveness over AoA, see the plot below of the XFOIL calculation for a Wortmann FX71-L-120 symmetric airfoil with a 25% flap at a Reynolds number of 1 Million and with a fixed boundary layer transition at 60% of chord. Note especially the hysteresis close to the maximum and minimum lift angles of attack at higher deflection angles (own work; c$_a$ is the lift coefficient).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DOAFT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DOAFT.jpg&quot; alt=&quot;Lift and pitching moment coefficients of a Wortmann FX71-L-120&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-09T09:05:46.307" LastActivityDate="2018-06-09T09:05:46.307" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15667" PostTypeId="2" ParentId="833" CreationDate="2015-06-10T22:49:40.773" Score="5" Body="&lt;p&gt;Landing point is extremely small for the speed the aircraft approach at for landing.&#xA;Landing point pitches up and down.&#xA;Landing point is not stationary, but is a moving point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The metal underground won't matter. It will have a special friction surface. It is very sturdy. The cable will stop the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-10T22:49:40.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15668" PostTypeId="2" ParentId="15634" CreationDate="2015-06-10T23:02:17.523" Score="3" Body="&lt;p&gt;Despite all that, some helicopters still vibrate significantly. Some helicopters, mainly designed and built by Eurocopter/Airbus can be adjusted to be flying without vibration (EC155, EC225, EC175 for instance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the main items to get right is the so-called rotor-track and balance (RTB). Older or smaller helicopters need specific maintenance for RTB using a stroboscope to see if all the blades follow the same track. This can only be done on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helicopters have a camera-system fitted that is able to capture the track of each blade. A computer system knows which blade is in the camera view and upon return can make a recommendation how to adjust the trim-tabs. This can only be done by day and won't work under specific lighting conditions (camera pointing too much into the light for instance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the newest helicopters don't even have a camera anymore, but accelerometers on the gearbox and the computer knows the position of each blade and calculates the necessary adjustments to be made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the RTB is done right, the active anti vibration system has little work to do. This is rarely done to perfection as most operators accept it when it is within 'manufacturer tolerances', so there still is vibration. To get it perfect costs time (and money).&lt;/p&gt;&#xA;" OwnerUserId="8771" LastEditorUserId="1696" LastEditDate="2018-03-21T19:21:15.347" LastActivityDate="2018-03-21T19:21:15.347" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15669" PostTypeId="2" ParentId="15181" CreationDate="2015-06-10T23:13:28.830" Score="4" Body="&lt;p&gt;Computers can be programmed to fly formation, but there are no autopilots in production yet that can handle it. The industry is trying to develop it so that airliners can fly in a V-formation in the cruise, like birds, in order to save about 5% in fuel. It would also alleviate congested skies if airliners could pair up. This would need very accurate positioning sensors that also work at night and in 0 visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The secret is to make small control adjustments. One will be oscillating with large amplitude, but low frequency. Learn to control it (straight-and-level first of course) and slowly bring it closer to the lead a/c. Your brain will recognize patterns of how to react to disturbances over time.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastEditorUserId="8547" LastEditDate="2015-06-12T06:20:59.193" LastActivityDate="2015-06-12T06:20:59.193" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15670" PostTypeId="2" ParentId="13039" CreationDate="2015-06-10T23:17:33.040" Score="1" Body="&lt;p&gt;And you won't land in a hover with larger helicopters at maximum weight. You will have some forward speed (unless you have wind in excess of 30-40 knots on the nose).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that sequence sounds a bit basic, but not unreasonable.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-06-10T23:17:33.040" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15671" PostTypeId="1" AcceptedAnswerId="15675" CreationDate="2015-06-11T04:15:03.983" Score="3" ViewCount="236" Body="&lt;p&gt;Pilots need to go through a checklist before they take off. Are these procedures decided by the airlines and (or) the manufacturer, or by the Civil Aviation Regulatory Authority of the respective country?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-10-14T03:39:32.103" Title="Who decides the regular procedure followed by the pilots before takeoff?" Tags="&lt;commercial-aviation&gt;&lt;pilots&gt;&lt;checklist&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15672" PostTypeId="1" AcceptedAnswerId="15708" CreationDate="2015-06-11T05:30:55.057" Score="5" ViewCount="619" Body="&lt;p&gt;Before the crew boards the aircraft for a commercial airline flight, is there anyone who checks the instruments and avionics system? I'm sure the engines are checked  but what about the avionics systems, instruments, sensors,etc.? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was an accident due to an incorrect reading of the pitot sensor, is there somebody to check it?&lt;/p&gt;&#xA;" OwnerUserId="8094" LastEditorUserId="62" LastEditDate="2015-06-11T18:57:42.273" LastActivityDate="2015-06-12T00:23:33.053" Title="Who checks the instruments and avionics before the crew boards an aircraft?" Tags="&lt;flight-instruments&gt;&lt;avionics&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15673" PostTypeId="1" AcceptedAnswerId="15674" CreationDate="2015-06-11T06:00:06.397" Score="8" ViewCount="2949" Body="&lt;p&gt;Trim tabs are used on the tail's horizontal elevators to adjust its neutral position. What is the working principle behind this? How does this affect the sensitivity (the feel) of the pitch to the pilot in a plane with no fly by wire?&lt;/p&gt;&#xA;" OwnerDisplayName="user8823" LastEditorUserId="62" LastEditDate="2015-06-13T19:56:43.407" LastActivityDate="2015-06-13T19:56:43.407" Title="What is the working principle of trim tabs on the elevators?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;&lt;trim&gt;&lt;trim-tab&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15674" PostTypeId="2" ParentId="15673" CreationDate="2015-06-11T06:46:21.470" Score="6" Body="&lt;p&gt;The trim tab is like a control surface for the control surface. By changing camber at the rear end of the control surface, it creates a local force which changes the balance of forces such that the force-free deflection angle (sometimes called auswehwinkel after the German word for this angle) is shifted in a direction opposite to the deflection of the tab.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could do the same with springs along the control rods, or a mass somewhere which pulls the control surface to the same force-free angle. But when speed changes, so do the aerodynamic forces, and your force-free angle will change. The forces caused by the tab change with airspeed, so the force-free angle set by a tab is unaffected by speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't confuse a trim tab with a Flettner tab: The trim tab stays at the same angle with varying control deflection, while the Flettner tab will move in opposite direction to reduce the stick forces caused by the deflection of the control surface. By setting the zero-deflection position of a Flettner tab, it can in parallel work like a trim tab and shift the zero-force deflection angle to the desired point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small aircraft like the Diamond Katana even have an anti-Flettner, where the tab is moving in the same direction as the control surface in order to increase stick forces. This is needed to fulfill certification requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, a combination of both springs and tabs is used to set the desired control forces and their gradient over speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-11T06:55:12.110" LastActivityDate="2015-06-11T06:55:12.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15675" PostTypeId="2" ParentId="15671" CreationDate="2015-06-11T07:03:45.957" Score="4" Body="&lt;p&gt;The manufacturer will publish a checklist.  Some airlines will choose to use the manufacturer's checklist verbatim, while others will adapt it to their specific operation based on things like safety reporting data from their fleet.  The end result will need to be approved by the regulating authority (in the US, the FAA -- specifically the Certificate Management Office or CMO for that airline) before it's used by crews.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of how an airline might modify the checklist would be to adapt it in light of new Human Factors research.  Telling crews to &quot;run this checklist&quot; during some large interval of time (say, between leaving the gate and reaching the runway, or between leaving cruise altitude and starting the approach) can lead to a missed checklist, and research recommends &quot;anchoring&quot; the checklist to some cue that's unlikely to be missed.  So, &quot;run THIS checklist before you release brakes and start to taxi, and THIS checklist when you have about 2000' left to taxi before reaching the end of the runway, and THESE 3 items as you take the runway for departure&quot; gives crews anchor points that they'll observe anyway and leave them less likely to look back and wonder &quot;did we read the Before Takeoff checklist?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer might have made it all one long 15-item checklist that they have crews read &quot;whenever,&quot; but the airline could separate out the items that are best accomplished before starting to taxi (knowing that the more items you put here, the longer the delay before the aircraft starts moving), the items that can be accomplished while taxiing (probably not stuff that requires a lot of 'heads down' time like reviewing the FMC routing), and the items that should be delayed until immediately before departure (strobes lights, landing lights, radar etc).&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-11T07:03:45.957" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15676" PostTypeId="5" CreationDate="2015-06-11T07:06:13.593" Score="0" Body="&lt;p&gt;Changing the setting of a trim tab adjusts the neutral or resting position of a control surface (such as an elevator or rudder). As the desired position of a control surface changes (corresponding mainly to different speeds), an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position—to zero, if used correctly. Thus the trim tab acts as a servo tab. Because the center of pressure of the trim tab is farther away from the axis of rotation of the control surface than the center of pressure of the control surface, the moment generated by the tab can match the moment generated by the control surface. The position of the control surface on its axis will change until the torques from the control surface and the trim surface balance each other.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-11T07:32:10.787" LastActivityDate="2015-06-11T07:32:10.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15677" PostTypeId="4" CreationDate="2015-06-11T07:06:13.593" Score="0" Body="Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-11T07:32:20.363" LastActivityDate="2015-06-11T07:32:20.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15678" PostTypeId="2" ParentId="15181" CreationDate="2015-06-11T07:23:28.180" Score="3" Body="&lt;p&gt;As far as fighter aircraft or small light aircraft flying as the wingman in formation, I agree with that's been said in the other answers.  However, larger aircraft than these can fly formation, and in some cases autopilot use is a little more common than these answers might lead you to believe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the lead aircraft has an entirely different task than the wingmen: his objective is to be a stable platform for them to maintain formation off of, and so for Lead to have the autopilot engaged is entirely possible in many scenarios.  (Not so much if Lead needs to do lots of maneuvering, but if you're going a long distance straight &amp;amp; level, the autopilot can do that very precisely, leaving the pilot(s) free to devote attention to whatever other tasks may be required: communicating with AWACS/wingmen/Command Post/ground party/other flights, assessing the situation with regards to threats/weather/mission/whatever, eating lunch, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of Aerial Refueling, it's fairly common for the tanker to be on autopilot, since this gives the most stable platform for receivers.  When the receivers are more nimble than the tanker, this isn't such a big deal; when the receiver is another heavy, it helps.  When the receiver is really heavy and performance limited, having a stable lead (i.e. the tanker) helps a LOT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond this, wingmen can also be on autopilot if the type of formation allows it.  If you're stacked 500' above and a mile behind Lead, crossing the ocean for the next several hours, there's no reason at all not to use the autopilot!  If you have the waypoints that Lead is using, you could even couple the autopilot to the FMC, and just adjust the throttles to maintain the desired spacing.  If not, then you manipulate the heading bug to keep the position you want left/right.  At the point when you get ready to do something like airdrop or a formation landing, the autopilot will come off, but for a long, straight cruise portion, it's entirely usable.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-11T07:23:28.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15680" PostTypeId="1" CreationDate="2015-06-11T09:44:34.500" Score="3" ViewCount="1159" Body="&lt;p&gt;How does a landing gear on an aircraft reduce the vibrations transferred to the airplane structure, while landing?&lt;/p&gt;&#xA;" OwnerDisplayName="user8824" LastEditorUserId="19" LastEditDate="2016-07-04T12:38:28.647" LastActivityDate="2016-07-04T12:38:28.647" Title="How does the landing gear damp vibrations?" Tags="&lt;landing&gt;&lt;landing-gear&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15681" PostTypeId="1" AcceptedAnswerId="15703" CreationDate="2015-06-11T10:40:07.927" Score="3" ViewCount="460" Body="&lt;p&gt;&lt;em&gt;After reading the answers I now know there are three independent sensors. I will leave the question as-is, to not take the answers out of context:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do remember reading that airliners have two independent sensors and channels to deliver readings like airspeed and altitude to the cockpit (pitot-static system).&#xA;  &lt;em&gt;If this is not the case my question will not make sense.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the two systems show conflicting information, what is the standard procedure? If one of them is 'overspeed' or close to stall speed should the pilots assume this is the one to focus on? Or do the pilots reason based on each situation independently and all the other factors at play?&lt;/p&gt;&#xA;" OwnerUserId="8818" LastEditorUserId="19" LastEditDate="2017-01-25T07:37:33.450" LastActivityDate="2017-01-25T07:37:33.450" Title="What is the standard procedure in case of inconsistent sensor readings?" Tags="&lt;aircraft-systems&gt;&lt;flight-instruments&gt;&lt;cockpit&gt;&lt;pitot-static&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15682" PostTypeId="2" ParentId="15681" CreationDate="2015-06-11T10:47:25.313" Score="3" Body="&lt;p&gt;There are at least three systems. You compare indicators with the standby system and know which one of the main systems failed. Sometimes all systems can fail due to icing or bird strikes. In this case there is an unreliable air speed procedure or checklist. Basically aircraft is flown by pitch and power settings.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-06-11T10:47:25.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15683" PostTypeId="2" ParentId="15636" CreationDate="2015-06-11T10:53:30.110" Score="1" Body="&lt;p&gt;Plug and play is a standard developed by IBM and Microsoft around the time windows 95 was released.  The old Plug N Play standard is an attempt to make device discovery and configuration a zero touch process for end users.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PNP standard has moved on since that time, however I could imagine some computer devices in the avionics bay utilizing USB, ISA busses to communicate and may very well comply with PnP standards of some type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only key component really missing is the User and the Windows operating system.  So while discovery and auto-config, conflict resolution Plug N play protocols maybe present in the electronics onboard an aircraft, but likely not in support of the windows operating system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In comparison to the PC based hardware bus systems, ARINC version 573 is the base level of functionality required from onboard data busses. Compliant equipment can communicate while allowing the FDR to capture the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More modern standards in the 600+ families of standards/products are designed for more modular treatment of the aviation equipment. Very similar to telecommunications rack equipment has developed since moving to digital.  With modular systems based on a chassis providing comms services and power to add in cards of different capabilities and purposes. Also integrating with other separate devices that integrate via ethernet or other standard protocols to deliver the necessary services. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Telecoms and ARINC is a reasonable comparison both in form factor, technical requirements and practices.  ARINC for example utilizes Harvard biphase encoding of data, pioneered in telecoms to avoid signal state corruption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in short, plug n play doesn't exist at least in standards on aircraft as a consumer would expect PnP to be.  Device, Windows OS, hardware interface and zero touch attempt at config the device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0qq1t.png&quot; alt=&quot;Block Diagram of Flight Management system&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8375" LastEditorUserId="8375" LastEditDate="2015-06-11T14:46:09.147" LastActivityDate="2015-06-11T14:46:09.147" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15684" PostTypeId="1" AcceptedAnswerId="15789" CreationDate="2015-06-11T11:27:35.410" Score="12" ViewCount="1920" Body="&lt;p&gt;When fighter jets fire a missile, do they observe any kind of reaction force due to firing the missile? If yes, how is this observed by the pilot? If no, why not?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1467" LastEditDate="2018-03-05T13:58:39.117" LastActivityDate="2018-03-05T13:58:39.117" Title="Do fighter jets experience a reaction or recoil force upon firing a missile?" Tags="&lt;fighter&gt;&lt;missiles&gt;&lt;dogfighting&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15685" PostTypeId="5" CreationDate="2015-06-11T11:28:34.063" Score="0" Body="&lt;p&gt;Modern terminology for air-to-air combat is air combat maneuvering (ACM), which refers to tactical situations requiring the use of individual basic fighter maneuvers (BFM) to attack or evade one or more opponents. This differs from aerial warfare, which deals with the strategy involved in planning and executing various missions.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-11T13:32:40.727" LastActivityDate="2015-06-11T13:32:40.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15686" PostTypeId="4" CreationDate="2015-06-11T11:28:34.063" Score="0" Body="A dogfight or dog fight, is an aerial battle between two or more fighter aircraft, conducted at close range. Dogfighting first appeared during World War I, shortly after the invention of the airplane. Until at least 1992, it was a component in every major war, despite beliefs after World War II that increasingly greater speeds and longer range weapons would make dogfighting obsolete." OwnerUserId="8547" LastEditorUserId="8282" LastEditDate="2017-07-28T14:49:30.683" LastActivityDate="2017-07-28T14:49:30.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15687" PostTypeId="5" CreationDate="2015-06-11T11:29:40.150" Score="0" Body="&lt;p&gt;Missiles come in types adapted for different purposes: surface-to-surface and air-to-surface missiles (ballistic, cruise, anti-ship, anti-tank, etc.), surface-to-air missiles (and anti-ballistic), air-to-air missiles, and anti-satellite weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All known existing missiles are designed to be propelled during powered flight by chemical reactions inside a rocket engine, jet engine, or other type of engine. Non-self-propelled airborne explosive devices are generally referred to as shells and usually have a shorter range than missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ordinary British-English usage predating guided weapons, a missile is &quot;any thrown object&quot;, such as objects thrown at players by rowdy spectators at a sporting event.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-11T13:32:12.557" LastActivityDate="2015-06-11T13:32:12.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15688" PostTypeId="4" CreationDate="2015-06-11T11:29:40.150" Score="0" Body="In modern military usage, a missile, or guided missile, is a self-propelled precision-guided munition system, as opposed to an unguided self-propelled munition, referred to as a rocket.  All known existing missiles are designed to be propelled during powered flight by chemical reactions inside a rocket engine, jet engine, or other type of engine." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T09:04:53.600" LastActivityDate="2015-06-17T09:04:53.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15689" PostTypeId="2" ParentId="15672" CreationDate="2015-06-11T12:46:17.540" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Before crew board the aircraft for a commercial airline, is there any person who checks the instruments and avionics systems&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In between flights there is no check of Pitot tube operation from the cockpit prior to crew arrival.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;There was an accident due to incorrect reading of pico sensor&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There have been a few accidents where one pitot tube (not pico sensor) was blocked (e.g. by the actions of a mud dauber wasp). This can lead to inconsistent readings in the two pilot's displays and/or with data fed to an autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example was &lt;a href=&quot;http://en.wikipedia.org/wiki/Birgenair_Flight_301&quot; rel=&quot;nofollow&quot;&gt;Birgenair 301&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-11T13:17:55.037" LastActivityDate="2015-06-11T13:17:55.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15690" PostTypeId="1" AcceptedAnswerId="15698" CreationDate="2015-06-11T12:49:44.500" Score="8" ViewCount="1231" Body="&lt;p&gt;I know that flight simulators (which are used to train the pilots for commercial airlines) try to simulate almost all kind of weather conditions, but how effectively and realistically are they able to reproduce turbulence in the simulated environment?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-06-11T18:54:28.680" LastActivityDate="2017-05-09T21:53:59.850" Title="Do flight simulators imitate turbulence effectively?" Tags="&lt;flight-simulator&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15691" PostTypeId="1" AcceptedAnswerId="15694" CreationDate="2015-06-11T13:01:00.343" Score="45" ViewCount="170573" Body="&lt;p&gt;I was reading this &lt;a href=&quot;https://aviation.stackexchange.com/questions/2163/how-do-commercial-pilots-send-distress-signals&quot;&gt;question&lt;/a&gt; about how do pilots send distress signals in emergency scenarios, and that got me thinking...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In voretaq7's answer, he states that there are three ways to send distress signals, one of them is by the aircraft's transponder&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Three transponder codes are reserved for unusual/emergency situations:&lt;br&gt;&#xA;   - &lt;code&gt;7700&lt;/code&gt; for general emergencies.&lt;br&gt;&#xA;   - &lt;code&gt;7600&lt;/code&gt; for loss of communication    (radio failure).&lt;br&gt;&#xA;   -  &lt;code&gt;7500&lt;/code&gt; for hijacking or other unlawful    interference.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can understand the reason to squawk both &lt;code&gt;7500&lt;/code&gt; and &lt;code&gt;7600&lt;/code&gt; in the appropriate situation, but I'm failing to understand why squawk &lt;code&gt;7700&lt;/code&gt; in an emergency scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So that's what I'm thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of a hijack, the ability to squawk &lt;code&gt;7500&lt;/code&gt; to silent alert the ATC of the situation, without the hijacker knowing, &lt;strong&gt;is an advantage&lt;/strong&gt;. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of a radio failure, where you can't alert the ATC over the radio, the ability to squawk &lt;code&gt;7600&lt;/code&gt; and make them aware of your situation, &lt;strong&gt;is an advantage&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of emergency, where the pilots are trying to handle a lot of things (high workload scenario), to stop everything to configure the aircraft's transponder, when they are communicating with the ATC by radio, &lt;strong&gt;doesn't seem like a good thing to do&lt;/strong&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, finally, here are my questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it common for pilots to squawk &lt;code&gt;7700&lt;/code&gt; in emergency scenarios?&lt;/li&gt;&#xA;&lt;li&gt;What are the advantages, for the pilots, to squawk &lt;code&gt;7700&lt;/code&gt; in emergencies situations?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="15904" LastEditDate="2017-08-09T19:19:13.843" LastActivityDate="2019-06-30T01:55:41.573" Title="What are the advantages of squawking 7700?" Tags="&lt;emergency&gt;&lt;radio-communications&gt;&lt;transponder&gt;" AnswerCount="9" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15692" PostTypeId="1" CreationDate="2015-06-11T13:02:52.670" Score="2" ViewCount="98" Body="&lt;p&gt;If one of the two engines of an aircraft is running at slightly less RPM then the other, how the synchronization is being managed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if there are more than 2 engines in the aircraft, how that will effect?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="595" LastEditDate="2016-04-26T07:41:33.697" LastActivityDate="2016-04-26T07:41:33.697" Title="How is the synchronization of multiple engines managed in twin engined aircraft?" Tags="&lt;engine&gt;" AnswerCount="0" CommentCount="0" FavoriteCount="1" ClosedDate="2015-06-11T13:28:59.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="15693" PostTypeId="2" ParentId="15691" CreationDate="2015-06-11T13:09:18.123" Score="11" Body="&lt;p&gt;Because it gets highlighted immediately on ATC's equipment, without needing a lengthy radio message to describe the problem and identify one's position.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-06-11T13:09:18.123" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15694" PostTypeId="2" ParentId="15691" CreationDate="2015-06-11T13:28:09.500" Score="73" Body="&lt;p&gt;If you make a radio call, unless you are on 121.5 (or 243 military), then only the station you are talking to will initially know about the emergency. Initial calls should always be with the unit you are working with unless you are VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you squawk 7700, then all stations in transponder range, including possible airborne stations such as AWACS and SAR will know right away that you are in trouble, with position, altitude and possibly aircraft type and flight number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If VFR, you might not be talking to anyone and may not have the frequencies of nearby units easily to hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Squawking 7700 is definitely a good thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You mentioned being busy.  The mantra drilled into everyone is &quot;aviate, navigate, communicate&quot;.  In most circumstances, fly the plane, fly it where you want it to go, then tell someone about it.  Squawking 7700 will be one of the last actions carried out.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2017-07-16T09:44:22.173" LastActivityDate="2017-07-16T09:44:22.173" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15695" PostTypeId="2" ParentId="13039" CreationDate="2015-06-11T13:44:54.523" Score="0" Body="&lt;p&gt;Those are exactly the 4 phases: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;entry -- lower the collective to keep the RPMs up&lt;/li&gt;&#xA;&lt;li&gt;auto-rotation flight -- keep the needle at the required RPM. 90% will give you a longer glide, but the horn will be blaring&lt;/li&gt;&#xA;&lt;li&gt;flare -- use the kinetic energy in the airspeed to arrest the descent near the ground. 50 feet is pretty high. Watch some youtube videos of full-down autos in your type of copter to get a sense of the height&lt;/li&gt;&#xA;&lt;li&gt;hover auto -- just above the ground, expend the energy in the rotating blades by pulling all the way up on the collective to cushion the landing. you will need a lot of pedal here too, otherwise you will yaw&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-06-11T13:44:54.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15698" PostTypeId="2" ParentId="15690" CreationDate="2015-06-11T14:04:53.590" Score="6" Body="&lt;p&gt;No, simulators cannot realistically simulate turbulence. Turbulence is characterized by significant changes in altitude that happen very quickly, and even full motion simulators aren't going to be able to re-create that. They can bump you around a bit, but not really prepare you for the real thing. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-06-11T14:04:53.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15699" PostTypeId="2" ParentId="15691" CreationDate="2015-06-11T14:07:57.460" Score="37" Body="&lt;p&gt;Aircraft squawking 7700 are getting a special indication (e.g highlighted, distinct colour, boxed) on Air Traffic Control (ATC) displays. This helps to identify the emergency aircraft not only to the air traffic controller who is controlling the airspace the aircraft is in, but also to controllers of other (nearby) airspaces. This helps to improve awareness and coordination within ATC. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In case of emergency, where the pilots are trying to handle a lot of things (high workload scenario), to stop everything to configure the aircraft's transponder, when they are communicating with the ATC by radio, &lt;strong&gt;doesn't seem like a good thing to do&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Typically communication to ATC, including setting the transponder to the general emergency code is of low priority during an emergency:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Aviate (make sure the aircraft keeps flying), &lt;/li&gt;&#xA;&lt;li&gt;Navigate (make sure you know where you are going, don't fly into terrain while trouble shooting), &lt;/li&gt;&#xA;&lt;li&gt;Communicate (let others know what you are doing)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Usually communication to ATC will be done using radio communications, but in some cases that may be difficult and setting 7700 will get the message that something is wrong across. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often ATC will ask to squawk 7700 after the initial Mayday call to identify the aircraft not only to the controller you are talking to, but to other controllers responsible for nearby sectors as well. This aids in coordination between controllers and makes sure appropriate action can be taken by controllers of adjacent airspace / airports in preparation of the emergency aircraft's transition into their area of responsibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=9KhZwsYtNDE&quot;&gt;video with ATC recordings&lt;/a&gt; of an emergency situation at Manchester airport shows you an example of ATC requesting an aircraft to squawk 7700 (at 2:00).&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-06-11T15:03:19.390" LastActivityDate="2015-06-11T15:03:19.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15700" PostTypeId="2" ParentId="15681" CreationDate="2015-06-11T14:27:08.090" Score="3" Body="&lt;p&gt;Avionics computers are generally (if not always) &lt;a href=&quot;http://history.nasa.gov/computers/Ch4-4.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;triple redundant&lt;/a&gt; to avoid the very situation you bring up. Form a pure logic standpoint you cant know which reading is correct if you only have 2 readings in a blind situation. However if you have 3 readings, 2 in agreement and 1 that differs you can statistically assume that the 2 agreed readings are correct. There is a nice summary &lt;a href=&quot;http://en.wikipedia.org/wiki/Triple_modular_redundancy&quot; rel=&quot;nofollow noreferrer&quot;&gt;here on Wikipedia&lt;/a&gt;. &lt;a href=&quot;https://aviation.stackexchange.com/questions/3416/what-is-the-purpose-of-multiple-autopilots&quot;&gt;This Question&lt;/a&gt; on why there are multiple autopilots also addresses it nicely. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-11T16:41:54.090" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15701" PostTypeId="2" ParentId="15391" CreationDate="2015-06-11T15:46:27.330" Score="7" Body="&lt;h1&gt;Australia, Austria, Brazil, Canada, Costa Rica, New Zealand, Russian Federation, Senegal, and Ukraine&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.flypast60.com/Documents/ICAO%20Council%20177%20Working%20Paper%20Appendix%20C.pdf?id=1581&amp;amp;wit_id=4480&quot; rel=&quot;noreferrer&quot;&gt;a 2006 ICAO report&lt;/a&gt; (mentioned also in &lt;a href=&quot;http://www.icao.int/NACC/Documents/Meetings/2011/AVMED2011/Day01-06-ICAO-Evans.pdf&quot; rel=&quot;noreferrer&quot;&gt;this presentation&lt;/a&gt;) (emphasis mine),&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Nine States (Australia, Austria, Brazil, Canada, Costa Rica, New Zealand, Russian Federation, Senegal, and Ukraine) have no upper age limit&lt;/strong&gt;, whereas fifty-five have an upper age limit higher than 60 years, ranging from 62 to 72 years.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This, of course, applies only to domestic flights, not &lt;a href=&quot;http://www.icao.int/safety/aviation-medicine/Pages/medFAQ_en.aspx#age&quot; rel=&quot;noreferrer&quot;&gt;international flights&lt;/a&gt;, as I imagine you have already read about:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ICAO Council adopted on 10 March 2006 an amendment to Annex 1 — Personnel Licensing that increases by five years the upper age limit for commercial pilots operating two-pilot aircraft, subject to conditions. The new provisions become applicable on 23 November 2006 and read as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2.1.10.1 A Contracting State, having issued pilot licences, shall not permit the holders thereof to act as pilot-in-command of an aircraft engaged in international commercial air transport operations if the licence holders have attained their 60th birthday or, in the case of operations with more than one pilot where the other pilot is younger than 60 years of age, their 65th birthday.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2.1.10.2 Recommendation.— A Contracting State, having issued pilot licences, should not permit the holders thereof to act as co-pilot of an aircraft engaged in international commercial air transport operations if the licence holders have attained their 65th birthday.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the ICAO typically gives constituents recommendations, not necessarily enforceable laws. Those are generally up to the countries themselves, which is why these nine are able to not have upper age limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wanted some confirmation on the original list from something more recent, so I checked out a few sources. I was only able to find information for two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Australia&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.casa.gov.au/scripts/nc.dll?WCMS:STANDARD::pc=PC_90028&quot; rel=&quot;noreferrer&quot;&gt;the Civil Aviation Safety Authority&lt;/a&gt;, it is noted that the ICAO age limits for pilot in command (PIC) and co-pilot are not relevant in Australian domestic flights, and seems to imply that age does not affect the ability to hold a pilot's license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Canada&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best I could find was this article from &lt;em&gt;&lt;a href=&quot;http://www.theglobeandmail.com/life/at-what-age-should-pilots-call-it-quits/article4281257/&quot; rel=&quot;noreferrer&quot;&gt;The Globe and Mail&lt;/a&gt;&lt;/em&gt;, originally from 2009 but possibly updated in 2012.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There is no upper age limit to acquire or renew a pilot licence in Canada - all you have to do is log the hours, complete the training and pass the medical exams, when necessary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7810" LastEditorUserId="7810" LastEditDate="2015-06-13T22:36:03.800" LastActivityDate="2015-06-13T22:36:03.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15702" PostTypeId="1" AcceptedAnswerId="15706" CreationDate="2015-06-11T07:32:58.060" Score="1" ViewCount="495" Body="&lt;p&gt;I would like to know the aileron lengths for different aircraft, such as: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Cessna &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_150&quot; rel=&quot;nofollow&quot;&gt;150&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Airbus &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;nofollow&quot;&gt;A380&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320_family&quot; rel=&quot;nofollow&quot;&gt;A320&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Boeing &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow&quot;&gt;747&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow&quot;&gt;777&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;787&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Lockheed Martin &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow&quot;&gt;F-22 Raptor&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I have tried to search online, but was unsuccessful in finding the values. I also tried searching in some books but couldn't find the values there either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any help guiding me to the books or any resources which would give me the values would be highly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="8825" OwnerDisplayName="Pratik Nayak" LastEditorUserId="7532" LastEditDate="2017-12-13T01:17:20.150" LastActivityDate="2017-12-13T01:17:20.150" Title="What are the aileron lengths of commercial and military aircraft?" Tags="&lt;ailerons&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15703" PostTypeId="2" ParentId="15681" CreationDate="2015-06-11T16:26:03.707" Score="4" Body="&lt;p&gt;The procedure used would depend on which information is conflicting/unreliable (and of course the aircraft type).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With one or more unreliable airspeed indications (which is one of the more critical ones), the initial action is NOT to start troubleshooting/figuring out which indicator is &quot;the correct one&quot;, but to ensure safe speed/flight path by other means. The initial actions on Boeing aircraft is to disconnect automatics (auto throttle, autopilot, flight director) and control the aircraft given memorized combinations of pitch and thrust. With the aircraft under control, and when directed by the checklist, you start analyzing the situation, to see if you can rectify/isolate the faulty source. If a reliable source can not be determined, the aircraft continues to be flown by pitch/thrust settings given in the manual (based on altitude, if known, weight, flaps/gear, desired vertical profile etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of unreliable altitude, in case you can't determine a reliable source, you can typically use radio altitude below 2'500 ft. A big caveat is that if the transponder is set to use an unreliable static pressure source, the altitude that ATC sees on secondary radar will also be unreliable. An example of this was seen in the Aeroperú 603 accident, where the aircraft took off, with the static ports taped over, and ATC was asked to assist with altitude and speed information: &lt;a href=&quot;http://www.avweb.com/news/safety/183038-1.html&quot; rel=&quot;nofollow&quot; title=&quot;CVR transcript&quot;&gt;CVR transcript&lt;/a&gt; - &lt;a href=&quot;http://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603&quot; rel=&quot;nofollow&quot; title=&quot;Wikipedia&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Erroneous airspeed/altitude indications often imply each other, as an unreliable static pressure source will affect both.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-06-11T22:34:39.717" LastActivityDate="2015-06-11T22:34:39.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15704" PostTypeId="1" AcceptedAnswerId="15705" CreationDate="2015-06-11T17:13:21.200" Score="9" ViewCount="1477" Body="&lt;p&gt;I was recently asked if an airport was covered by a Letter to Airmen (LTA) providing IFR separation for VFR practice approaches, and I realized I had no idea. How can I look up LTAs for an airport, and do they ever expire?&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-11T17:39:36.967" Title="Where can I look up FAA Letters to Airmen?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15705" PostTypeId="2" ParentId="15704" CreationDate="2015-06-11T17:35:58.770" Score="10" Body="&lt;p&gt;They are searchable at FNS NOTAM search: &lt;a href=&quot;https://notams.aim.faa.gov/notamSearch/&quot;&gt;https://notams.aim.faa.gov/notamSearch/&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A link is provided to a PDF, containing a link to the actual LTA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Filter by LTA, remember the agreement might not be with the airport, but with the ATSU, like the local TRACON/ARTCC, try searching by airport name + radius).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Expiry date is shown in the details view.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-06-11T17:39:36.967" LastActivityDate="2015-06-11T17:39:36.967" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15706" PostTypeId="2" ParentId="15702" CreationDate="2015-06-11T18:55:41.737" Score="3" Body="&lt;p&gt;This is quite difficult to answer as some modern supersonic fighters  don't have just ailerons, but 'elevons', flaperons, tailerons and most of the time combine the movement of several control surfaces by computer to generate a desired effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large civilian aircraft tend to have more than one pair. A relatively smaller set closer to the wing tips for slower speeds and a general large aileron closer to the wing root.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would suggest you get a top-view of these aircraft. When you find our the length of the aircraft or wingspan you could derive it yourself through approximation.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastEditorUserId="39" LastEditDate="2015-06-28T21:56:30.550" LastActivityDate="2015-06-28T21:56:30.550" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15707" PostTypeId="2" ParentId="15586" CreationDate="2015-06-11T19:02:09.750" Score="4" Body="&lt;p&gt;If you don't want to use an instructor - which is the best and safest way to get those 25 hours - there are only two other ways I can think of to get them: use a safety pilot; or use time logged under another instrument rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1109&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.109&lt;/a&gt; explains the safety pilot requirements:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) No person may operate a civil aircraft in simulated instrument&#xA;  flight unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The other control seat is occupied by a safety pilot who possesses&#xA;  at least a private pilot certificate with category and class ratings&#xA;  appropriate to the aircraft being flown.&#xA;  [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that if you use a safety pilot you have to log his/her name per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.51&lt;/a&gt; and - contrary to somewhat popular belief - the safety pilot &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/August/1/Pilot-Counsel-Safety-pilot&quot; rel=&quot;nofollow noreferrer&quot;&gt;does require a current medical&lt;/a&gt; (at least according to AOPA's lawyers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second way would be if you already have or had an instrument rating, probably a foreign one. In that case, the time logged under your foreign privileges is acceptable to the FAA for ratings purposes (see &lt;a href=&quot;https://aviation.stackexchange.com/q/154/62&quot;&gt;this question&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that your instructor will &lt;em&gt;not&lt;/em&gt; sign you off for solo instrument flight after 15 hours. There is no instrument rating equivalent of the private solo endorsement: you can only fly under IFR (or below VFR minimums) after you pass the IR checkride. Even if you use an instrument rated 'safety pilot' in IMC then he must be acting PIC because you have no instrument rating. If you try to get around those rules you'll either &lt;a href=&quot;https://aviation.stackexchange.com/q/9764/62&quot;&gt;kill yourself&lt;/a&gt; or &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow noreferrer&quot;&gt;be operating illegally&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-05-16T13:08:56.143" LastActivityDate="2017-05-16T13:08:56.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15708" PostTypeId="2" ParentId="15672" CreationDate="2015-06-11T19:30:52.837" Score="5" Body="&lt;p&gt;In general, nobody else does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When pilots arrive to an aircraft for the first flight of the day, extra checks are performed by the crew to verify aircraft systems are all working properly.  These checks are done once per day and subsequent flights will perform abbreviated checks instead.  A visual walk around inspection is accomplished before and after every flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintenance will check on airplanes at required intervals but outside of specific checks (associated with the carriers approved maintenance program) the only time they'll check something like a pitot tube is if the crew notes a problem and writes it up.  At that point maintenance will address the issue to return the aircraft to airworthiness.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-06-11T19:30:52.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15709" PostTypeId="1" CreationDate="2015-06-11T19:34:04.397" Score="8" ViewCount="2322" Body="&lt;p&gt;How do you set correct heading while cruising across latitudes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a flat map, point A might be to point B at, say, heading 060 (intentionally no cardinal headings taken for example, as they don't create this situation). But on a curved surface, like spherical earth, the heading doesn't remain constant- it keeps changing as you move away from or toward the equator, sending aircraft miles off-target over long distances, as a result of pole-bound spiraling of the path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a formula to determine the optimum heading at the outset (even though it may not 'seem' correct), thereby, reaching the desired point B on the globe at the end of the cruise?&lt;/p&gt;&#xA;" OwnerUserId="8828" LastEditorUserId="62" LastEditDate="2015-06-13T19:52:32.613" LastActivityDate="2015-06-13T19:52:32.613" Title="Do autopilot headings consider the earth's shape?" Tags="&lt;navigation&gt;&lt;autopilot&gt;&lt;heading&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15710" PostTypeId="1" AcceptedAnswerId="15712" CreationDate="2015-06-11T19:42:05.967" Score="10" ViewCount="1292" Body="&lt;p&gt;Was travelling on a Airbus A320 (night flight) and during the safety briefing noticed that the  fluorescent floor lighting strip referred to in the evacuation instructions was totally absent.  Both sides of the aisle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could see the marks on the floor carpet where it must have been earlier tacked on. Was removed and went unreplaced for whatever reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it OK for an aircraft to fly without this item? Seemed pretty essential to me for a safe evacuation in the dark. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I did try &amp;amp; take a photo but unfortunately didn't come out so well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hPf7r.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-06-12T17:14:04.030" LastActivityDate="2015-06-12T17:30:26.137" Title="Is the emergency fluorescent floor lighting strip along the aisle an item on the MEL?" Tags="&lt;airbus&gt;&lt;evacuation&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15711" PostTypeId="2" ParentId="15709" CreationDate="2015-06-11T19:56:25.717" Score="13" Body="&lt;p&gt;Yes, almost all modern computer navigation systems take this into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The track between two points along the &quot;spherical&quot; earth is called the &lt;a href=&quot;http://en.wikipedia.org/wiki/Great-circle_navigation&quot; rel=&quot;nofollow&quot;&gt;great-circle track&lt;/a&gt;. Except for a N/S heading (or a E/W heading at the equator), the heading will vary along the track. Ed Williams has compiled a formulary for great circle navigation &lt;a href=&quot;http://williams.best.vwh.net/avform.htm#Intro&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, mostly derived from the &lt;a href=&quot;http://en.wikipedia.org/wiki/Haversine_formula&quot; rel=&quot;nofollow&quot;&gt;Haversine formula&lt;/a&gt;. The formula you are interested in is &quot;Course between points&quot; for calculating the initial heading to fly from point A to point B.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7172" LastEditDate="2015-06-12T11:19:48.330" LastActivityDate="2015-06-12T11:19:48.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15712" PostTypeId="2" ParentId="15710" CreationDate="2015-06-11T20:03:52.717" Score="6" Body="&lt;p&gt;According to &lt;a href=&quot;http://fsims.faa.gov/wdocs/mmel/a-320%20r21.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this document&lt;/a&gt; the answer would appear to be no if all lights were missing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vj58n.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 1/1 columns indicates the number installed and required for dispatch.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-06-11T20:03:52.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15713" PostTypeId="2" ParentId="14889" CreationDate="2015-06-11T20:22:01.843" Score="4" Body="&lt;p&gt;&lt;em&gt;This is a personal experience rather than an authoritative answer, but I thought it would be relevant.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fly a few airlines fairly frequently and have done for many years. I've always thought that blinds should be open for safety reasons. However, a few years back I was on a flight with an airline that I'd flown many times before and had always enforced the blinds-open policy. To my surprise everyone was asked to close the window blinds. Within a year the trend had increased to point where all flights by this airline were blinds-closed. Then, a year or so after that, the policy was reverted to blinds-open and has remained since.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;My theory&lt;/em&gt; is that someone in the senior crew, or crew training, mixed up the policy and started enforcing the wrong one (i.e. blinds-closed). I think this is plausible as the reasons for having blinds-open are not entirely obvious. It would also explain the gradual adoption of the new policy. I guess someone eventually realised the mistake, hence the sudden reversal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for the long post and lack of sources. Will delete if deemed not helpful.&lt;/p&gt;&#xA;" OwnerUserId="8818" LastActivityDate="2015-06-11T20:22:01.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15714" PostTypeId="2" ParentId="14715" CreationDate="2015-06-11T21:01:49.373" Score="1" Body="&lt;p&gt;If anyone came here like me looking for the ability to just rent in Canada once in a while, You can go &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/managementservices-referencecentre-acs-400-400-003-122.htm#s5-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;here&lt;/strong&gt;&lt;/a&gt; and fill out the form. Apparently it only takes 2 days and costs $45 to get the Foreign License Validation Certificate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have to actually go to a Transport Canada office, which is a huge inconvenience if you aren't in one of the few Canadian cities that has one, but when you do go it's pretty straight forward, and your license validation lasts for a year. &lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="4509" LastEditDate="2017-08-30T17:41:24.420" LastActivityDate="2017-08-30T17:41:24.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15716" PostTypeId="1" CreationDate="2015-06-11T22:02:30.470" Score="11" ViewCount="1131" Body="&lt;p&gt;Are there any regulations that requires that international airports maintain a navigation channel deep enough to have access in case of an emergency when the airport runway ends near a body of water?&lt;/p&gt;&#xA;" OwnerUserId="8830" LastEditorUserId="5517" LastEditDate="2016-07-06T12:00:52.157" LastActivityDate="2016-07-06T12:00:52.157" Title="Are there specific regulations for airports near water bodies?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15717" PostTypeId="2" ParentId="15716" CreationDate="2015-06-11T22:20:47.490" Score="11" Body="&lt;p&gt;Yes, there are ICAO regulations requiring water rescue facilities. For example, from &lt;a href=&quot;https://www.aucklandairport.co.nz/Corporate/NewsAndMedia/AllMediaReleases/New-marine-rescue-fleet-launched-at-Auckland-Airport.aspx&quot;&gt;New marine rescue fleet launched at Auckland Airport&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airports which have a significant proportion of aircraft movements over water are required by the International Civil Aviation Organisation (ICAO) to provide a specialist rescue facility, capable of an effective response in a marine area around the airport. Marine rescue craft are required to be able to transport sufficient flotation equipment to an accident site to support the number of people carried in the largest aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can find this regulation in the &lt;a href=&quot;http://www.icao.int/safety/Implementation/Library/Manual%20Aerodrome%20Stds.pdf&quot;&gt;ICAO Aerodrome Standards&lt;/a&gt; document:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;Emergencies in difficult environments&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;9.1.14 The plan shall include the ready availability of and coordination with appropriate specialist rescue services&#xA;  to be able to respond to emergencies where an aerodrome is located close to water and/or swampy areas and where a significant&#xA;  portion of approach or departure operations takes place over these areas.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;9.1.15 At those aerodromes located close to water and/or swampy areas, or difficult terrain, the aerodrome&#xA;  emergency plan shall include the establishment, testing and assessment at regular intervals of pre-determined response for the&#xA;  specialist rescue services.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that this does not necessarily require a &lt;em&gt;navigation channel&lt;/em&gt;, as rescue operations can be primarily provided by hovercraft (as in Auckland).&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-06-11T22:20:47.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15718" PostTypeId="2" ParentId="15709" CreationDate="2015-06-11T23:11:37.163" Score="8" Body="&lt;p&gt;You wrote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On a flat map, point A might be to point B at, say, heading 060. [...] Is there a formula to determine the optimum heading at the &lt;strong&gt;outset&lt;/strong&gt; (even though it may not 'seem' correct), thereby, reaching the desired point B on the globe at the end of the cruise?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As written in the other answer, this is not how large distanced are flown, as aircrafts follow great circles for a minimal distance. But if you want to fly a constant heading from your outset, this can be done:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine, you have one of these illuminated globes and put it into a paper cylinder, such that the cylinder touches the equator everywhere. All contours of the earth are projected against the cylinder, and you can retrace them with a pen. Unfold the cylinder, and you get a &lt;em&gt;mercator projection&lt;/em&gt;:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/mYl3v.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mathematically, this can be calculated by this conversion of earth coordinates:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$x=\text{&amp;lt;longitude&amp;gt;}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$y=\mathop{\rm arsinh}(\tan(\text{&amp;lt;latitude&amp;gt;}))$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and drawing this into a coordinate system where unit length is equal for x and y. (the labels on the y-axis are not y-coordinates, they denote the  latitude.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you see, the face of the earth is vertically warped, and the size of continents is not preserved. For example,  Greenland seems to be of the same size as Africa, though it's actually only 7%. Also, distances are not preserved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;BUT: Angles are preserved!&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Draw a straight line from your location to any destination, and read the angle between this line and the vertical lines. Follow this heading, and you will reach your destination. Mathematically, you can determine the course by the following formula, but keep in mind that the arctan function does not always give you the correct formula. You need to know if you have to fly NE, SE, SW or NW and apply this do the value. (Can be done automatically with more math, too.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\alpha=\arctan\frac{x_{dest}-x_{depart}}{y_{dest}-y_{depart}}$$&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As said above, distances are not preserved. This straight lines are by far not the shortest routes and your passengers will complain about the long flight, as well as your airline about all the burned fuel...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question in the comment:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a standard mercator projection as above, only pure north-south tracks as well as tracks on the equator lie on great circles and so are the shortest route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, you can put that paper cylinder around your globe in an other orientation, for example touching the 0-meridian instead of the equator. This way, you get the transversal mercator projection, which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jtMEO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(by Lars H. Rohwedder, &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Transversal_Mercator_0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://commons.wikimedia.org/wiki/File:Transversal_Mercator_0.jpg&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this map, straight horizontal lines will lie on great circles, but the heading (angle to meridians) will change during flight. &#xA;You can also use other arbitrary orientations for the cylinder, like &lt;a href=&quot;http://commons.wikimedia.org/wiki/File:Transversal_Mercator_45E.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;this 45° projection&lt;/a&gt;, looking even more weired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you are searching for a constant heading and don't care about distance, the standard mercator projection gives the answer.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-06-12T10:05:23.730" LastActivityDate="2015-06-12T10:05:23.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15719" PostTypeId="2" ParentId="15709" CreationDate="2015-06-12T00:09:53.873" Score="-1" Body="&lt;p&gt;Yes. They fully take into account that the world is flat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just kidding. Long distance route planning is a complicated process. Usually commercial flights follow fixed, well-established routes. For example, when flying from North America to Europe, aircraft generally use &lt;a href=&quot;http://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot; rel=&quot;nofollow&quot;&gt;North Atlantic Tracks&lt;/a&gt;. These tracks are designed in a way that is fully cognizant of the oblate sphericity of the Earth.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="8837" LastEditDate="2015-06-12T13:15:26.410" LastActivityDate="2015-06-12T13:15:26.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15720" PostTypeId="2" ParentId="15672" CreationDate="2015-06-12T00:23:33.053" Score="-1" Body="&lt;p&gt;In theory the pilot in command (the Captain) has responsibility for making sure everything works before flight. On small aircraft responsible pilots always check all instruments and sensors. For example, a pitot tube will be checked to make sure that it is clear and that no spider or mud wasp has taken up residence therein. Another key check is to make sure the antennas are all there and firmly attached. Most checklists have at bare minimum an &quot;instruments&quot; line item and may have many line items for specific instruments. When a pilot does the &quot;walk around&quot; they will specifically examine each and every external sensor such as static ports, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, commercial pilots rarely have time to do such thorough checks, which can be very time consuming for a large aircraft. In many cases they will often not even do a walk around, even if their airline's policy mandates it.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-12T00:23:33.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15721" PostTypeId="1" AcceptedAnswerId="15732" CreationDate="2015-06-12T02:31:11.843" Score="11" ViewCount="2323" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Airworthiness Directives (ADs) are legally enforceable regulations issued by the FAA in accordance with 14 CFR part 39 to correct an unsafe condition in a product. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Hence when an AD is issued, owner must comply with the AD within the stated time period in order to remain airworthy. This compliance ,of course, come with some cost. Who pay for this cost of compliance? Owner of the plane? Manufacturer? Or they somehow share the cost?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="396" LastEditDate="2015-06-13T12:37:05.600" LastActivityDate="2015-06-13T12:37:05.600" Title="Who pays for the compliance with Airworthiness Directives (AD)?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;airworthiness-directive&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15722" PostTypeId="2" ParentId="15691" CreationDate="2015-06-12T03:58:49.450" Score="2" Body="&lt;p&gt;When you squawk 7700 you have to use your brains and hands to do other things besides flying the plane and troubleshooting your emergency.  You also light up the controllers scope like a Christmas tree, which is very distracting, causing them to quickly assign you a discreet code, meaning that you will be tempted to move your hands, yet again, to something that doesn't matter.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much easier than squawking is to simply declare an emergency on the radio frequency you are already monitoring.  If I need to literally move my hands to squawk emergency then I've probably given up on the FAR/AIMS anyway because I'm about to die.  IE, electrical failures effecting both radios probably caused by a dual engine fire affecting both generators. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;77, going to heaven&quot;--your mileage may vary.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-06-12T05:33:42.817" LastActivityDate="2015-06-12T05:33:42.817" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15723" PostTypeId="2" ParentId="15721" CreationDate="2015-06-12T04:01:47.417" Score="8" Body="&lt;p&gt;The cost of complying with an AD falls on the owner/operator of the aircraft. Failing to comply with an AD renders the aircraft unairworthy. It also could incur FAA penalties, but more importantly, it could result in structural damage or failure, and in some cases ultimately cause a fatal accident.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-12T04:01:47.417" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15724" PostTypeId="1" AcceptedAnswerId="15725" CreationDate="2015-06-12T06:14:10.573" Score="9" ViewCount="4898" Body="&lt;p&gt;How to identify that a given fan is a compressor fan or a turbine fan, just by visual inspection? Also, can visual inspection of a fan help in identifying the compressor/turbine stage i.e. if the fan is from a High Pressure Turbine/Compressor blade or Low Pressure Turbine/Compressor blade?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-07-04T11:31:38.240" LastActivityDate="2016-07-04T11:31:38.240" Title="What is the visual difference between turbine fans and compressor fans?" Tags="&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15725" PostTypeId="2" ParentId="15724" CreationDate="2015-06-12T06:21:34.380" Score="12" Body="&lt;p&gt;&lt;strong&gt;Assuming we are speaking of axial compressors/turbines&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compressor blades are generally thin and straight, and resemble a tiny rectangular wing with low camber thickness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Aqw06.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;http://www.bagotvillemuseum.ca/en/info-images.php?id=208&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Turbine blades are more curved, often in almost &quot;U&quot; shapes (like the ones seen &lt;a href=&quot;https://aviation.stackexchange.com/questions/14501&quot;&gt;here&lt;/a&gt;). In particularly large and recent engines, where efficiency is critical, turbine blades will often be full of tiny holes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/QwnKu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;http://aerospaceengineeringblog.com/turbine-cooling/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To distinguish between high pressure and low pressure stages (compressor or turbine does not matter), the length of the blade and its torsion (i.e. how much the aerodynamic profile turns around the axis of the blade going from the root to the tip) are key: shorter and more twisted blades will be high pressure ones, longer and straighter blades will be low pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that two blades of the same length could come one from a high pressure stage and the other from a low pressure one of a different engine: &quot;short&quot; and &quot;long&quot; are relative to the engine size.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On the other hand, radial compressors and radial turbines are more difficult to distinguish.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-12T06:36:47.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15726" PostTypeId="2" ParentId="2999" CreationDate="2015-06-12T08:41:15.060" Score="2" Body="&lt;p&gt;Powered light aircraft can make sustained flight with engines off when their flight path aligns with hill or mountain ranges receiving steady wind on one face. In certain environments and weather conditions these ranges generate Wave lift that is substantial enough to allow high speed flight at altitudes exceeding 20,000ft in silky smooth conditions over many 1000s of kilometres. Associated with these conditions are extreme rotors outside the band of lift. Sailplane pilots (eg Delore in NZ Dec 2009 2500km) have set world record long flights using extensive ranges that form the spine of both Islands.&lt;/p&gt;&#xA;" OwnerUserId="8833" LastActivityDate="2015-06-12T08:41:15.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15727" PostTypeId="1" CreationDate="2015-06-12T08:42:56.813" Score="7" ViewCount="965" Body="&lt;p&gt;I was looking at the description of this role i.e. someone who provides cruise flight relief flying. As conceivably, someone could be bonded for multiple years because of the type rating being covered by the airline, it is possible they could 'fly' for multiple years and yet never actually do a real takeoff or landing?&lt;/p&gt;&#xA;" OwnerUserId="396" LastActivityDate="2015-09-03T14:41:55.663" Title="Can cruise pilots/second officers go for years without doing a takeoff or landing?" Tags="&lt;pilots&gt;&lt;cruise&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15728" PostTypeId="1" AcceptedAnswerId="15776" CreationDate="2015-06-12T09:02:51.887" Score="30" ViewCount="65781" Body="&lt;p&gt;According to &lt;a href=&quot;http://boeing.mediaroom.com/2015-03-18-Boeing-747-8-Intercontinental-Receives-FAA-Approval-for-330-Minute-ETOPS&quot; rel=&quot;noreferrer&quot;&gt;this press release&lt;/a&gt; by Boeing earlier this year, the 747-8 has received its ETOPS 330 rating. This is required by all 4-engined planes made after February 2015 to fly beyond 180 minutes from an en-route alternate airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this apply only when one engine has already failed? I understand four-engine jets usually continue to their destination on three engines. And how does this compare to the 747-400. Can it fly ETOPS 330+ routes? I remember them doing missions that twin-engine aircraft couldn't because of their lack of ETOPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A follow-up question for those who are interested: &lt;a href=&quot;https://aviation.stackexchange.com/questions/15783/why-does-etops-not-apply-to-older-4-engine-aircraft/15838#15838&quot;&gt;Why does ETOPS not apply to older 4 engine aircraft?&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8818" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2020-05-29T09:25:14.523" Title="What is ETOPS and how does it work?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;aircraft-certification&gt;&lt;boeing-747&gt;&lt;etops&gt;" AnswerCount="5" CommentCount="18" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15729" PostTypeId="1" AcceptedAnswerId="15740" CreationDate="2015-06-12T09:06:13.953" Score="6" ViewCount="11725" Body="&lt;p&gt;I've seen the position of Second Officer being advertised for some short-haul airlines, but I don't entirely understand what roles and responsibilities they have on the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know a second officer exists on long-haul flight, which allows for crew to take rest breaks through the duration of the flight. So what do they do on short-haul flights? Are they still under line training?&lt;/p&gt;&#xA;" OwnerUserId="8834" LastActivityDate="2015-06-12T15:28:34.167" Title="What is a Second Officer?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15732" PostTypeId="2" ParentId="15721" CreationDate="2015-06-12T11:35:51.227" Score="9" Body="&lt;p&gt;It depends on the agreements between the operator/owner of the aircraft on one side and the manufacturer of the aircraft and its suppliers on the other side. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often there will be some form of compensation involved if an AD is issued when that AD is addressing non-compliance with regulations / standard in effect when the aircraft was produced. Normally there is some time limited warranty covering the costs of ADs at least partially.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-12T11:35:51.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15733" PostTypeId="1" AcceptedAnswerId="15736" CreationDate="2015-06-12T11:39:32.277" Score="36" ViewCount="42916" Body="&lt;p&gt;This has been puzzling for quite a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every action movie or military documentary features helicopters with no door or with open doors and yet people inside look like they couldn't care less. Apparently they're not falling out...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it so?&lt;/p&gt;&#xA;" OwnerUserId="8835" LastEditorUserId="595" LastEditDate="2015-06-24T06:52:39.280" LastActivityDate="2019-03-23T01:44:43.413" Title="Flying in a helicopter with open doors: why don't people fall out?" Tags="&lt;helicopter&gt;" AnswerCount="15" CommentCount="20" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15734" PostTypeId="1" AcceptedAnswerId="15738" CreationDate="2015-06-12T12:13:51.637" Score="16" ViewCount="10184" Body="&lt;p&gt;I see medical emergency helicopters taking off and landing several times a day from the hospital near my office. As I understand from an earlier question, they are probably flying VFR, below controlled airspace and &lt;a href=&quot;https://aviation.stackexchange.com/questions/13335/why-do-helicopter-flights-not-appear-in-online-flight-trackers/13336#13336&quot;&gt;likely without ADS-B&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would assume, however, that these flights are in touch with the local ATC, and they are certainly announcing their presence on the locally monitored channel(s). Is there a particular set of call signs or other indicators that are used by these flights to indicate to other traffic that, while this flight itself is not in any sort of mayday situation, it needs priority handling and that everyone else needs to get out of the way as lives depend on the speed of this particular flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am asking particularly for the USA/FAA, but would be interested to know if there are differences in other countries around the world.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2017-05-29T13:26:39.727" Title="What callsign would a medical emergency flight use?" Tags="&lt;radio-communications&gt;&lt;emergency-services&gt;&lt;medevac&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15735" PostTypeId="2" ParentId="15734" CreationDate="2015-06-12T12:26:35.190" Score="11" Body="&lt;p&gt;The US call sign is &quot;MEDEVAC.&quot; It used to be &quot;LIFEGUARD,&quot; but was &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/flight_plan_filing/general/icao_2012/media/AIM%20Changes%20for%20ICAO%202012.pdf&quot;&gt;changed in 2012&lt;/a&gt; as part of the transition to ICAO flight plans, which suggests that &quot;MEDEVAC&quot; could be a standard (though I'm not sure if it is).&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-06-12T12:26:35.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15736" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T12:50:49.813" Score="46" Body="&lt;p&gt;Aircraft, fixed-wing or rotorcraft, have limited capability to produce a sideways force, so they simply can't throw you out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a matter of physics. Inertial forces (gravity and centrifugal force) act on you and the aircraft the same, so they won't make you move relative to the aircraft. The only force between you and the seat is caused by the aerodynamic forces. And the wing or rotor can only produce significant force vertically, and some torque with help of control surfaces. But for lateral force there is only drag of the fuselage and the vertical stabilizer and, in most helicopters, anti-torque rotor, which don't produce that much force unless there is really bad turbulence or in some cases if the handling is really bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aircraft turns, it banks to be able to produce the necessary side force, so the resulting force is still mostly straight to the floor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the other reason is that all aircraft and helicopters have seat-belts and the people sitting by open door usually have them on—except for skydivers, who have the parachute on already, and rescue divers who are tied to the winch instead.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-12T13:03:01.360" LastActivityDate="2015-06-12T13:03:01.360" CommentCount="21" ContentLicense="CC BY-SA 3.0" />
  <row Id="15737" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T12:56:01.630" Score="25" Body="&lt;p&gt;The reason that the occupants are so calm about being in an open helicopter are because they are strapped in. There are many configurations that open helicopters can have, some with seats and some not. The seats are generally removable, connecting to points on the floor. Occupants in the back have 2 options for strapping in, the first is your typical seat belt, the other is known as a &quot;monkey harness&quot;, which is a harness that goes around your shoulders and waist and can be clipped to points in the floor. Door gunners usually preferred harnesses because it allowed much more freedom of movement so they could fire at more angles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember also that these people were used to it as well. I'm sure most of them were bricking it big-time their first few trips no matter how well they were strapped in. Also, I suppose when you're about to be shot at falling out may frighten you less than it may otherwise. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-06-12T12:56:01.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15738" PostTypeId="2" ParentId="15734" CreationDate="2015-06-12T13:58:49.003" Score="21" Body="&lt;p&gt;The variety of callsigns used for medical flights are covered in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;AIM 4-2-4&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. Air Ambulance Flights.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Because of the priority afforded air ambulance flights in the ATC system, extreme discretion is necessary when using the term “MEDEVAC.” It is only intended for those missions of an urgent medical nature and to be utilized only for that portion of the flight requiring expeditious handling. When requested by the pilot, necessary notification to expedite ground handling of patients, etc., is provided by ATC; however, when possible, this information should be passed in advance through non−ATC communications systems.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Civilian air ambulance flights responding to&#xA;  medical emergencies (first call to an accident scene,&#xA;  carrying patients, organ donors, organs, or other&#xA;  urgently needed lifesaving medical material) will be&#xA;  expedited by ATC when necessary. When expeditious&#xA;  handling is necessary, include the word&#xA;  “MEDEVAC” in the flight plan per paragraphs 5−1−8&#xA;  and 5−1−9. In radio communications, use the call&#xA;  sign“MEDEVAC,” followed by the aircraft registration&#xA;  letters/numbers.&#xA;  &lt;em&gt;EXAMPLE− MEDEVAC Two Six Four Six.&lt;/em&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Similar provisions have been made for the use&#xA;  of “AIR EVAC” and “HOSP” by air ambulance&#xA;  flights, except that these flights will receive priority&#xA;  handling only when specifically requested.&lt;/li&gt;&#xA;  &lt;li&gt;Air carrier and air taxi flights responding to&#xA;  medical emergencies will also be expedited by ATC&#xA;  when necessary. The nature of these medical&#xA;  emergency flights usually concerns the transportation&#xA;  of urgently needed lifesaving medical materials&#xA;  or vital organs. IT IS IMPERATIVE THAT THE&#xA;  COMPANY/PILOT DETERMINE, BY THE&#xA;  NATURE/URGENCY OF THE SPECIFIC&#xA;  MEDICAL CARGO, IF PRIORITY ATC ASSISTANCE&#xA;  IS REQUIRED. Pilots must include the word&#xA;  “MEDEVAC” in the flight plan per paragraphs 5−1−8&#xA;  and 5−1−9, and use the call sign “MEDEVAC,”&#xA;  followed by the company name and flight number for&#xA;  all transmissions when expeditious handling is&#xA;  required. It is important for ATC to be aware of&#xA;  “MEDEVAC” status, and it is the pilot’s responsibility&#xA;  to ensure that this information is provided to ATC.&#xA;  &lt;em&gt;EXAMPLE−&#xA;  MEDEVAC Delta Thirty−Seven&lt;/em&gt;.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-06-12T13:58:49.003" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15739" PostTypeId="2" ParentId="3070" CreationDate="2015-06-12T14:06:33.147" Score="13" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/97/danny-beckett&quot;&gt;@Danny Beckett&lt;/a&gt; has already covered the more luxurious variants of reclining seats very well, but I wanted to answer your point about &quot;wasted space&quot;. The space above the passengers' heads is currently used for hand luggage, so you'd need to find somewhere else to store that. But even if you solved that, there are a few major issues to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The maximum number of passengers in a plane is limited by the number and size of the doors (for evacuation, you need to be able to get all passengers out in 90 seconds in case of a crash landing). If you put more people into the cabin you would need more/larger doors, so depending on the design of the plane it might not be feasible to try and cram more passengers in. (see also: &lt;a href=&quot;https://aviation.stackexchange.com/questions/8866/are-there-examples-current-or-historical-of-commerical-aircraft-seating-arrang/8874#8874&quot; title=&quot;unusual seating arrangements&quot;&gt;unusual seating arrangements&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;The &quot;evacuate in 90 seconds&quot; rule bites you in a second way: In an emergency, getting out of a standard airline seat, running down the aisle, and out the door is (reasonably) quick. If you had to climb down from your bed under the ceiling first, it would take much more time. &lt;/li&gt;&#xA;&lt;li&gt;The rules for passenger safety &lt;em&gt;during&lt;/em&gt; a crash (or severe turbulence) are pretty strict. Any reclining chair can be put upright (and designers assume that passengers will have sufficient warning of a crash/turbulence to put their seats upright, and be reasonably well strapped in and protected), but if you're lying down there isn't a good way to stop you from bouncing off the walls or ceiling (or, even if you're wearing some kind of belt, from hitting your head on said walls or ceiling). In short, lying down is not a safe position to be in in an emergency.  &lt;/li&gt;&#xA;&lt;li&gt;From a practical point of view, I don't think flying while lying down in a cramped space is all that comfortable, especially for long-haul. You would have to climb down into the aisle to walk around or go to the toilet, you would have to eat/read/watch TV while lying down, not to mention the extra difficulty of climbing over the person in the berth next to you if there is more than one berth on each side of the aisle. (thank you to &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;@Peter Kämpf&lt;/a&gt; for the additional input!)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In conclusion, it's currently not technically feasible to design an airplane cabin which would meet aviation safety rules with bunks above the passenger heads. &lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-15T07:30:33.933" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15740" PostTypeId="2" ParentId="15729" CreationDate="2015-06-12T14:15:41.013" Score="6" Body="&lt;p&gt;&lt;strong&gt;Definition&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second officer (SO) is third in line of command on an airplane. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Second_officer_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;purpose of a second officer&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a Second Officer is used on international or long haul flights where&#xA;  more than two crew are required to allow for adequate crew rest&#xA;  periods.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have never seen anyone besides a captain and first officer on a short-haul flight. Such flights normally don't even require either the captain or first officer to take a break to rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Duties&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second officers are qualified pilots and also type-rated for the airplane they are on, similar to the captain and first officer, but only with lesser experience. I do not know the exact career path for them, but most probably they are &lt;em&gt;promoted&lt;/em&gt; to become first officers. This is same as first officers are promoted to become captains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Jobs&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are certainly jobs available for second officers, but only on airlines which operate long-haul flights. Regional airlines with flights only for a 2-3 hours don't require a second officer&lt;sup&gt;1&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://jobsatcathaypacific.com/cadetpilots/being-a-second-officer.php&quot; rel=&quot;nofollow&quot;&gt;Cathy Pacific&lt;/a&gt; is hiring (also &lt;a href=&quot;http://www.cathaypacific.com/cx/en_HK/about-us/careers/jobs-in-the-air/pilots.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;). The experience of a second officer on Cathy can be &lt;a href=&quot;https://www.pilotcareercentre.com/Pilot-Life-Story-Blog/141/Cathay+B747+Second+Officer&quot; rel=&quot;nofollow&quot;&gt;read here&lt;/a&gt;. Aviation Job Search is &lt;a href=&quot;http://www.aviationjobsearch.com/second-officer&quot; rel=&quot;nofollow&quot;&gt;listing many positions&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SO on Short-Haul&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each airline can have its own definition of second officer. What I wrote above is the general meaning. You mentioned &lt;a href=&quot;http://www.jet2careers.com/pilots&quot; rel=&quot;nofollow&quot;&gt;JetA&lt;/a&gt; and &lt;a href=&quot;http://www.pilotjobsnetwork.com/jobs/Thomson_Airways&quot; rel=&quot;nofollow&quot;&gt;Thomson&lt;/a&gt; (in comments to the deleted answer) but I couldn't find jobs for SO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Engineer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their role is different than pilots and now they are a diminishing breed. Most of them were not pilots. Again, an airline may label a flight engineer as second officer, though &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_engineer&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; did not mention that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: The aftermath of Germanwings crash can make some &lt;a href=&quot;https://en.wikipedia.org/wiki/Germanwings_Flight_9525#Regulatory&quot; rel=&quot;nofollow&quot;&gt;changes in regulations&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-06-12T15:28:34.167" LastActivityDate="2015-06-12T15:28:34.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15741" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T14:39:59.277" Score="8" Body="&lt;p&gt;Consider for a moment what would have to happen for you to fall out. That would have to happen either through gravity, or inertia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some rough over-the-thumb rationalizing (and keep in mind that I'm not a pilot, let alone a helicopter pilot -- just some basic physics applying here):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Gravity.&lt;/strong&gt; The helicopter would have bank at a significant angle, and at the same time &lt;em&gt;not&lt;/em&gt; have enough centripetal force (which would press you into your seat via inertia, as during a &quot;normal&quot; bank). For example, if the pilot forces the copter into a bank and then zeroes out on the collective. However, that same gravity will act on the chopper as well... uncomfortable low-g conditions, yes, and you probably would want to grab hold of something, but you don't get ripped out of your seat immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Inertia.&lt;/strong&gt; The helicopter would have to make a sudden &lt;em&gt;lateral&lt;/em&gt; movement, so you get jerked out of your seat. However, as others have pointed out already, a helicopter does not &lt;em&gt;have&lt;/em&gt; a way to induce sudden lateral movements of that magnitude. So, no dice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once we start considering &lt;em&gt;outside&lt;/em&gt; forces -- turbulence, high winds, blasts from ordonance fired at you -- you probably had enough sense to strap yourself in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the movies you've been seeing will be picturing helicopters operating in Vietnam, Iraq, Afghanistan, Somalia... see a pattern here? Those are &lt;em&gt;hot&lt;/em&gt; climates we're talking about. So, given that the &lt;em&gt;usual&lt;/em&gt; chopper ride is unlikely to toss you out of the door, why shouldn't people enjoy a bit of a breeze? ;-)&lt;/p&gt;&#xA;" OwnerUserId="2401" LastEditorUserId="595" LastEditDate="2015-06-24T06:55:30.330" LastActivityDate="2015-06-24T06:55:30.330" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15742" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T14:57:00.250" Score="5" Body="&lt;p&gt;I don't fly helicopters, but I can tell you that in fixed wing aircraft you &lt;strong&gt;always&lt;/strong&gt; strap in. I assume helicopters are the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane has no doors and you are not strapped in, you will have an excellent chance of falling out. I would assume the same is true for helicopters. Some of the other answerers have talked about centrifugal forces or whatever. In reality what happens is that gusts hit you and knock you around all the time. You don't notice the gusts in big aircraft like Airbuses, but in a small aircraft it can be like being inside of a barrel rolling down a mountain. You definitely do not want to be unsecured at any time in flight, especially with a door open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once I was getting towed in a glider and my harness popped open. In about 2 seconds my left foot was sticking straight up, wedged against the bubble canopy and my right knee was in my face. I was upside down. Meanwhile, the glider is moving around like Pirates of the Caribbean and the tow pilot is wondering, &quot;What the hell is he doing?&quot; I had to wedge myself against the sides of the glider and instrument panel like Jackie Chan to get the harness buckled again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the knuckleball motion of a gusted aircraft can be an advantage sometimes, such as when you need to deal with an unruly passenger. Just unbuckle his harness when he isn't looking, kick his door open and he will be singing &quot;Free Falling&quot; by Tom Petty in no time :-) Just kidding, of course, don't do that.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-06-12T16:52:16.727" LastActivityDate="2015-06-12T16:52:16.727" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="15743" PostTypeId="2" ParentId="15734" CreationDate="2015-06-12T15:26:15.560" Score="3" Body="&lt;p&gt;In Boston, where I live, medivacs use custom call signs that they pick for themselves. Medflight uses the generic &quot;Med One&quot;, &quot;Med Two&quot;, &quot;Med Three&quot;. &quot;Lifeflight&quot; that is run by the University of Massachusetts uses &quot;Lifeflight&quot; as their callsign. Northern Massachusetts is covered by the Dartmouth Hitchcock Advanced Response Team. They use &quot;DHART&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-12T15:26:15.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15744" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T15:30:38.483" Score="14" Body="&lt;p&gt;I taught sport skydiving for 10 years, and I have sat half-out of the open door of an aircraft, no seatbelt, hundreds of times while the aircraft makes 45 degree banks toward the open door side. It's a bit odd seeing the airport above the wingtip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless the plane is in a spin or otherwise spectacularly out of control, the forces are largely perpendicular to the floor of the aircraft. At no time have I ever felt like I was going to fall out, and actually getting out is difficult enough that we spend an hour or more practicing it on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You asked about helicopters specifically - they are less able to produce cross-fuselage forces than fixed-wing planes. Look at the rotor, then the thin post connecting the rotor hub to the fuselage. It's not that thick and thus cannot produce enough force to toss someone out the door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heavy turbulence could bounce you around to the point where falling out is possible. Not guaranteed, just possible if you bounce in that direction. But at low speeds and clear weather it's unlikely to the point where sitting down is adequate. Standing and moving around with an open door is common, but the 1 inch strap that is plenty strong enough to hold you up is very hard to see, especially on TV.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1632" LastEditDate="2015-06-13T06:59:42.377" LastActivityDate="2015-06-13T06:59:42.377" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15745" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T15:36:46.547" Score="1" Body="&lt;p&gt;If you mean when the helicopter banks then all the people are either strapped into their seats like your car seat belt as all the people above have mentioned or because the have a cord attached to their jacket. (The cord part is what I saw in a documentary on the Discovery Channel).&lt;/p&gt;&#xA;" OwnerUserId="8841" LastEditorUserId="97" LastEditDate="2015-06-12T18:46:29.380" LastActivityDate="2015-06-12T18:46:29.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15746" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T15:47:06.147" Score="0" Body="&lt;p&gt;People aren't falling because the cabin isn't pressurised.  If you would try to open the door in mid-air of your average passenger æroplane cruising in the upper troposphere, you would be &lt;em&gt;not amused&lt;/em&gt;.  People would be sucked out.  But helicopters usually don't fly at altitudes where pressure is a problem, so there is no cabin pressurisation, so there is no outward force due to an open door.&lt;/p&gt;&#xA;" OwnerUserId="1626" LastActivityDate="2015-06-12T15:47:06.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15747" PostTypeId="2" ParentId="15710" CreationDate="2015-06-12T17:22:32.117" Score="8" Body="&lt;p&gt;Those lights don't have to be mounted to the floor. They can also be seat mounted. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bruceind.com/index.php?option=com_k2&amp;amp;view=item&amp;amp;id=90:escape-path-lighting-systems&amp;amp;Itemid=189&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.bruceind.com/index.php?option=com_k2&amp;amp;view=item&amp;amp;id=90:escape-path-lighting-systems&amp;amp;Itemid=189&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.astronics.com/_images/aircraft-safety/EPM%20033010.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.astronics.com/_images/aircraft-safety/EPM%20033010.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8FvPa.png&quot; alt=&quot;Seat mounted escape path lights&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the AC that provides guidance on the requirements of the system. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25.812-1A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25.812-1A.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulation is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;SID=67a8813bf9d9da0aa64e74e2e5ced957&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:1.0.1.3.11.4.178.62&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;14CFR25.812&quot;&gt;14CFR 25.812&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-12T17:30:26.137" LastActivityDate="2015-06-12T17:30:26.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15748" PostTypeId="2" ParentId="8817" CreationDate="2015-06-12T18:16:09.093" Score="2" Body="&lt;p&gt;You are in some regards introducing a few questions here &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I was trying to think of requirements for building an aircraft that&#xA;  would be accessible to the masses&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Bringing aviation to the masses is only in part related to the aircraft its self. For what its worth the Piper Cherokee 140 can be had for less than most new cars and has what has been called &lt;a href=&quot;http://piperowner.org/articles/featured-aircraft/5-pa-28-cherokee-140-the-little-indian-that-could.html&quot; rel=&quot;nofollow&quot;&gt;&quot;Very Benigin&quot; handling&lt;/a&gt; some might even say making it to safe. The plane like most GA planes glides very easily and practicing engine outs is routine to get your license. Which brings up the more important point. The current US regulations set fourth by the FAA makes it much tougher to fly a plane (although sport pilot has helped this) than it does to drive a car. To be honest it does not take that much to legally drive a car here in the US. Learning to fly an airplane is a significantly larger task, it takes an investment (anywhere from 7K-15K depending on local flight school costs) and more time than learning to drive a car. This is really what keeps the masses from flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth new planes are not cheap not only because they are expensive to build but because FAA type certs are not easy to come buy. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;and the first thing I thought of was safe landing in the event of&#xA;  engine failure&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Engine failure is, (assuming there is no fire involved) a recoverable situation as long as there is an open field &lt;a href=&quot;http://www.cnn.com/2014/01/04/us/small-plane-new-york-highway/&quot; rel=&quot;nofollow&quot;&gt;or even a local parkway&lt;/a&gt; to put the craft down. Small planes (and most planes for that matter) glide fairly well and can be maneuvered under glide with ease. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;or other catastrophic mechanical breakdown.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The problem with this is that most of the clean handling characteristics of small GA planes are predicated on the fact that the plane is as it should be. There are a million and one things that can break but may will cause a situation that will alter the handling or flight characteristics of a plane like &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=73971&quot; rel=&quot;nofollow&quot;&gt;asymmetric flap deployment&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_with_disabled_controls&quot; rel=&quot;nofollow&quot;&gt;snapped control cables/disabled flight controls&lt;/a&gt; or even &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-6_Porter&quot; rel=&quot;nofollow&quot;&gt;critical air frame failures&lt;/a&gt; like the 2008 incident involving a Pilatus PC-6. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;could glide safely with no control input simply based on the way the&#xA;  frame of the aircraft was designed&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As has been mentioned most GA planes (at least the slower trainers) are made to return to a safe attitude to some extent. It should be noted that this often requires some kind of minimum altitude and many accidents happen at low altitude when the plane simply does not have time to recover. Some of this may also be effected by things like trim which if set to its limits has an effect on the planes handling. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-12T18:16:09.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15749" PostTypeId="2" ParentId="15733" CreationDate="2015-06-12T19:55:05.283" Score="2" Body="&lt;p&gt;To fall out of a helicopter, your center of gravity would have to lie outside of the aircraft.  Because helicopters tend to bank smoothly when they accelerate, your center of gravity stays within the aircraft.  Unless the aircraft were struck by another object, it is unlikely you would ever experience a significant lateral force while flying in a helicopter.&lt;/p&gt;&#xA;" OwnerUserId="8843" LastActivityDate="2015-06-12T19:55:05.283" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15750" PostTypeId="1" CreationDate="2015-06-12T20:46:40.713" Score="1" ViewCount="345" Body="&lt;p&gt;For my staff cadet course, I need to know what ACAI and ACTI stand for but I can't find it anywhere. Would anybody be able to notify me of what this means?&lt;/p&gt;&#xA;" OwnerUserId="8844" LastEditorUserId="19" LastEditDate="2016-07-04T11:16:10.033" LastActivityDate="2016-07-04T11:16:10.033" Title="What is the meaning of ACAI and ATCI in Air Cadets?" Tags="&lt;airline-operations&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15751" PostTypeId="2" ParentId="15750" CreationDate="2015-06-12T22:42:46.980" Score="2" Body="&lt;p&gt;Those four letters can be abbreviations for many things related to aviation. Taking into account that this is for a staff cadet course, I think the most likely candidates are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air Cadet Administrative&#xA;Instructions&lt;/li&gt;&#xA;&lt;li&gt;Air Cadet Training Instructions  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.967atc.co.uk/resources/air-cadet-publications/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8818" LastEditorUserId="8818" LastEditDate="2015-06-13T15:24:07.693" LastActivityDate="2015-06-13T15:24:07.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15753" PostTypeId="1" AcceptedAnswerId="15759" CreationDate="2015-06-12T22:55:31.833" Score="26" ViewCount="3886" Body="&lt;p&gt;I've been wondering this for quite a while:  Why do the missiles on the F-16 point down a little bit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mQQko.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mQQko.jpg&quot; alt=&quot;See how they point down?&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I went and did a little searching and found out that the F-16 isn't the only plane that has this feature, so I'm going assume it's not the F-16s frame specifically.  I also doubt it's tactical because all the weapons are pointing down, regardless of the weapons role in combat. In fact I saw a few photos where the bombs closest to the fuselage were pretty level with the ground (and bombs pretty much always go down, so...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it have to do with aerodynamics, or perhaps ease of loading?  Why is the load-out on the F-16 mostly pointed slightly downwards?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2016-02-17T16:37:37.273" LastActivityDate="2020-10-22T12:38:08.820" Title="Why do the missiles on an F-16 point slightly down?" Tags="&lt;aerodynamics&gt;&lt;military&gt;&lt;f-16&gt;" AnswerCount="8" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15754" PostTypeId="2" ParentId="15753" CreationDate="2015-06-13T00:22:30.647" Score="16" Body="&lt;p&gt;Usually stores are hung off an aircraft in such a manner to facilitate a safe auxiliary free-fall release.  The AUX release is used if the CAD misfires and the stores cannot be physically ejected downward away from the aircraft. Although this wouldn't really apply to the wingtip loaded aim 9's, so I can't really account for those.  In the super hornet the pylons are canted outwards for just this reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, the emergency jettison doesn't even release the wingtip aim 9's because, in the case of the Rhino, the wing is more efficient with them in place.  The wingtip 9's act as a winglet of sorts.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-06-13T04:14:38.997" LastActivityDate="2015-06-13T04:14:38.997" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15755" PostTypeId="2" ParentId="15753" CreationDate="2015-06-13T00:34:58.033" Score="-5" Body="&lt;p&gt;Its so that the thing goes down (and away) from the aircraft when it is released.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, imagine the missile was canted up instead of down. Due to aerodynamics it might fly into the wing it was released. The armament is canted downward to prevent this.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-13T00:34:58.033" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15756" PostTypeId="2" ParentId="8560" CreationDate="2015-06-13T00:51:45.310" Score="3" Body="&lt;p&gt;There is a big difference between the amount of torque delivered to the main rotor of a helicopter and that delivered to the propeller of a comparably-sized fixed wing aircraft. Also, without the tail rotor, a helicopter in a hover has nothing to &quot;push against&quot; in order to deliver the needed torque to the main rotor. If not for the tail rotor, torque delivered to the main rotor would cause the rest of the vehicle to spin up in the opposite direction. Hovering flight would be pretty much impossible without something to aerodynamically generate opposing torque (tail rotor, second counter-rotating rotor, etc.). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torque delivered to the propeller of a fixed-wing aircraft is opposed either through the ground (when stationary, taxiing or on take-off roll), or by the wings (with minor roll trim or control input) when in flight. As explained in the other answers, propeller torque does induce certain effects, but they are of much less significance than that of a helicopter main rotor, and are dealt with by trim and pilot awareness/handling.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-06-13T00:51:45.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15757" PostTypeId="2" ParentId="15733" CreationDate="2015-06-13T02:15:29.810" Score="1" Body="&lt;p&gt;Are you expecting them to fly out of the helicopter because in movies, when the plane/spaceship/whatever door is opened, people get sucked out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nsEKi.gif&quot; alt=&quot;airlock&quot;&gt;&lt;br&gt;&#xA;&lt;em&gt;(&lt;a href=&quot;http://backyardwars.tumblr.com/post/22577428129/death-by-airlock&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, that effect &lt;strong&gt;is&lt;/strong&gt; real &lt;em&gt;(though perhaps exaggerated)&lt;/em&gt;, but it's not caused by the craft's movement.  It's caused by the depressurization of the room.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inside has high pressure, while the outside has low pressure.  When a door opens, the high pressure inside-air moves towards the outside, exerting a force on anything it meets &lt;em&gt;(in the same way that the wind pulls you during a nasty storm)&lt;/em&gt;.  However, the effect dies down quickly as the pressure equalizes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a helicopter with open sides, that pressurization never happens to begin with, so there is no depressurization to pull the passengers out. &lt;/p&gt;&#xA;" OwnerUserId="7543" LastActivityDate="2015-06-13T02:15:29.810" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15759" PostTypeId="2" ParentId="15753" CreationDate="2015-06-13T03:19:06.660" Score="24" Body="&lt;p&gt;If you take a look at the picture again, you'll see that the missiles are in fact lined up quite nicely with the nose of the plane. The missiles are not pointed down, they are pointed forward. The wings and engine (and the entire back two-thirds of the plane) are pointed &lt;em&gt;up&lt;/em&gt;, which provides the lift to keep the plane in the air during normal flight. You can see pretty well the alignment in reference to the horizon in this picture (found by @jay-carr):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YLz3V.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YLz3V.jpg&quot; alt=&quot;Image of F16 showing nose and mounted missiles pointed at the horizon.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to cut off the potential comments about how planes generate lift, reference is &lt;a href=&quot;http://www.allstar.fiu.edu/aero/airflylvl3.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8849" LastEditorUserId="1696" LastEditDate="2016-02-17T16:36:08.373" LastActivityDate="2016-02-17T16:36:08.373" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="15760" PostTypeId="2" ParentId="15753" CreationDate="2015-06-13T04:14:24.507" Score="2" Body="&lt;p&gt;I believe it's a bit of &lt;a href=&quot;https://en.wikipedia.org/wiki/Washout_%28aeronautics%29&quot; rel=&quot;nofollow&quot;&gt;washout&lt;/a&gt; in the wing. Washout is a slight twist to the wing, reducing the angle of incidence at the tip and reducing the probability of tip stall.&lt;/p&gt;&#xA;" OwnerUserId="520" LastActivityDate="2015-06-13T04:14:24.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15761" PostTypeId="2" ParentId="15684" CreationDate="2015-06-13T06:02:52.677" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://youtu.be/9DYsYKFNSHo&quot;&gt;http://youtu.be/9DYsYKFNSHo&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ignore the actual purpose of the video and why the pilot is firing in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can clearly see that the missile separates from the aircraft before igniting the thrusters. Since the missile starts its thrusters without contact to the aircraft, no recoil is experienced.&lt;/p&gt;&#xA;" OwnerUserId="2461" LastActivityDate="2015-06-13T06:02:52.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15762" PostTypeId="2" ParentId="15750" CreationDate="2015-06-13T09:56:25.213" Score="0" Body="&lt;p&gt;&lt;strong&gt;ACAI&lt;/strong&gt; could stand for following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Afghanistan Civil Aviation Institute.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some building in Serbia, which is related to aviation. (&lt;a href=&quot;http://www.icao.int/Meetings/GACS/Documents/Speaker%20Presentations/Day%201/Session%202/3-Muzaffar.Ismail.Ministry%20of%20Transportation.Indonesia.pdf&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air Cadet Administrative Instructions. (&lt;a href=&quot;http://www.967atc.co.uk/resources/air-cadet-publications/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;ATCI&lt;/strong&gt; stands for Air Traffic Control Instruction.&#xA;This acronym appears very rarely. And refers to training of Air Traffic controllers.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8818" LastEditDate="2015-06-13T15:45:57.550" LastActivityDate="2015-06-13T15:45:57.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15763" PostTypeId="1" AcceptedAnswerId="15764" CreationDate="2015-06-13T10:32:33.297" Score="15" ViewCount="4565" Body="&lt;p&gt;Is it possible that in case of some very serious emergency, a commercial airliner such as the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB4QFjAAahUKEwi8keyJvIzGAhVLrLwKHc8xAJ4&amp;amp;url=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FBoeing_777&amp;amp;ei=9gZ8Vby-D8vY8gXP44DwCQ&amp;amp;usg=AFQjCNF7otwrTP06XAyqiIqposDL-40Bjg&amp;amp;sig2=99_sKkJhG7kqNOIpAAsXYQ&quot;&gt;B777F&lt;/a&gt; could be used for dropping bombs or to serve some other fighting purpose? &#xA; I am simply asking about this from a technical standpoint.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2015-06-13T19:46:12.690" LastActivityDate="2021-01-19T22:24:12.560" Title="Can a commercial airliner be used for military purposes?" Tags="&lt;airliner&gt;&lt;military&gt;" AnswerCount="8" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15764" PostTypeId="2" ParentId="15763" CreationDate="2015-06-13T11:20:59.527" Score="11" Body="&lt;p&gt;Retrofitting is (as the comments to your post have already stated) rather difficult and unusual. In addition, the quality of service from such an aircraft you could expect to get would most probably not be great. Analogy: Try changing your minibus for 9 people into minivan for freight and industrial work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also worth mentioning that the difference in operation is substantial between bombers and commercial jets. You would be better off using something that is not that complicated, like a Cessna Caravan for instance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that energy, time and money would be better spent on building more dedicated aircraft. Changing the commercial ones is also not trivial and will require engineered changes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It is however fully possible to design a military derivative of a commercial jet. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_P-8_Poseidon&quot;&gt;Boeing P-8 Poseidon&lt;/a&gt; is an example of this, being based off the Boeing 737 with the necessary modifications. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The armament is also fairly extensive:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5 internal and 6 external stations for AGM-84H/K SLAM-ER, AGM-84 Harpoon, Mark 54 torpedo, missiles, mines, torpedoes, bombs, and a High Altitude Anti-Submarine Warfare Weapon system[&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-13T11:31:07.553" LastActivityDate="2015-06-13T11:31:07.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15765" PostTypeId="2" ParentId="15763" CreationDate="2015-06-13T11:22:41.953" Score="6" Body="&lt;p&gt;Converting pretty much any passenger hauler into a bomber would be quite an exercise. You would have to add pressure bulkheads aft of the flight deck, rebuild the bottom of the fuselage to allow for doors, add considerable structure to hold the (very heavy) bomb racks, and probably remove the floor - rather tricky if the floor is also holding the fuselage together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Missiles on the wings would be comparatively easy - they are not as heavy and don't require major mods to the pressure hull.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &quot;serious emergency&quot; indicates urgency, and that gets met with existing aircraft. The time taken to modify a 777 into a bomber would be fairly close to building a new bomber. Although if it's a protracted war of attrition&amp;#42; I would expect Boeing would quickly design a new one based around the 777's tooling so they can get them out the door quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is very easy (and common) to use passenger haulers as troop transport. Conversion to AWACS is nowhere near as complex, I suspect someone already has plans in a file somewhere to do just that. And the USAF already uses DC-10 freighters as tankers - the boom is a not-overly-complex conversion and probe-drogue systems are almost bolt-ons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before anyone comments about it, the DC-10 used as a water bomber is &lt;em&gt;very&lt;/em&gt; different from dropping explosives. Water is a distributed load, and releasing it doesn't require half of the bottom of the plane to open up - it flows out through ports that can easily have structural members running across them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&amp;#42; World War II would be a good example. Evenly-matched belligerents, whoever has more resources usually wins. If WWIII goes nuclear it will be over in an hour or two.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="8022" LastEditDate="2015-06-16T22:30:56.560" LastActivityDate="2015-06-16T22:30:56.560" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15766" PostTypeId="2" ParentId="15753" CreationDate="2015-06-13T17:43:30.223" Score="6" Body="&lt;p&gt;It's not just the wingtip launchers that are canted downwards.  All pylons are canted downwards a couple degrees (~2 I believe).  This is to reduce the AOA to 0, thus reducing induced drag at pickle.  There might be more to it in terms of aerodynamics, but I didn't engineer the jet.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-13T17:43:30.223" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15768" PostTypeId="2" ParentId="15728" CreationDate="2015-06-13T23:07:34.703" Score="5" Body="&lt;p&gt;Boeing has a post about it here: &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_2_07/article_02_7.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.boeing.com/commercial/aeromagazine/articles/qtr_2_07/article_02_7.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, twins have to get ETOPS when they are more than 60 minutes from an airport, and planes with 3+ engines have to get it when they are more than 180 minutes from an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully that answers your question.&lt;/p&gt;&#xA;" OwnerUserId="7387" LastActivityDate="2015-06-13T23:07:34.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15769" PostTypeId="2" ParentId="15691" CreationDate="2015-06-13T23:17:39.177" Score="5" Body="&lt;p&gt;As many others have mentioned here, if you squawk 7700 you will be highlighted on the ATC screens.  ATC will in turn clear traffic around you.  The advantages to this are obvious if you consider that you may be suffering controllability problems that are preventing you from being able to maintain heading or altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Couple this with the fact you may also be having trouble communicating with ATC.  This may have nothing to do with radio trouble, as anyone can attest who has flown in a high density area (O'Hare, JFK, Atlanta, etc...) where the radio comms can be so clobbered that you can continually get stepped on.  Aviate, navigate, communicate and 7700 &lt;strong&gt;&lt;em&gt;is&lt;/em&gt;&lt;/strong&gt; communicating.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have had in-flight emergencies that I didn't put 7700 in because I already had a discreet squawk and ATC answered immediately when I declared the emergency with my intentions to turn and descend.  Had they not responded, I would have put 7700 in and done what I needed to do to handle the emergency knowing that ATC would vector other traffic around me.&lt;/p&gt;&#xA;" OwnerUserId="8210" LastEditorUserId="8210" LastEditDate="2016-01-02T01:17:19.737" LastActivityDate="2016-01-02T01:17:19.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15770" PostTypeId="2" ParentId="15728" CreationDate="2015-06-14T01:23:21.543" Score="7" Body="&lt;p&gt;ETOPS does not only affect the engines of an aircraft – long ETOPS ratings such as the 747-8's 330-minute ETOPS capability also require that systems like fire suppression be sufficient for over five (!) hours of flying &lt;em&gt;after&lt;/em&gt; something in the cargo hold sets itself ablaze.  This is accomplished by metering a flow of extinguishing agent into the cargo hold after the initial &quot;knockdown&quot; shot to keep the fire in check until the plane can land.  &lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="9818" LastEditDate="2017-07-11T07:49:16.187" LastActivityDate="2017-07-11T07:49:16.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15771" PostTypeId="1" AcceptedAnswerId="15777" CreationDate="2015-06-14T01:37:47.380" Score="1" ViewCount="2990" Body="&lt;p&gt;What is the P-Factor when we're talking about a Propeller Aerodynamics ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks&lt;/p&gt;&#xA;" OwnerUserId="8533" LastActivityDate="2015-06-14T07:33:20.323" Title="What is P-Factor in Propeller Aerodynamics?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-06-14T13:58:58.683" ContentLicense="CC BY-SA 3.0" />
  <row Id="15772" PostTypeId="1" AcceptedAnswerId="22490" CreationDate="2015-06-14T01:43:00.870" Score="8" ViewCount="34146" Body="&lt;p&gt;What is the best method to do Weight &amp;amp; Balance for a Cessna 172? (If it's possible with a small tutorial!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks&lt;/p&gt;&#xA;" OwnerUserId="8533" LastEditorUserId="7532" LastEditDate="2015-10-29T20:50:23.460" LastActivityDate="2019-04-15T22:25:22.400" Title="How to do Weight &amp; Balance for Cessna 172?" Tags="&lt;weight-and-balance&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15773" PostTypeId="2" ParentId="15771" CreationDate="2015-06-14T01:55:10.433" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://wiki.flightgear.org/Understanding_Propeller_Torque_and_P-Factor&quot; rel=&quot;nofollow&quot;&gt;P factor&lt;/a&gt; stems from the fact that the downward side of a propellor generates more thrust than the upward side (because of the helix like nature of the air flow). This manifests its self in a leftward tendency for American made engines, it should be noted that not all engines rotate the same way and its not uniformly a leftward tendency.  This causes the plane to yaw to the left under high power and high angle of attack situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is mainly prevalent in single engine prop planes. Twin engine planes (at least modern ones) tend to implement counter rotating propellors to counteract this. Older twins that have props rotating the same way have a &lt;a href=&quot;https://en.wikipedia.org/wiki/Critical_engine&quot; rel=&quot;nofollow&quot;&gt;critical engine&lt;/a&gt;   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-14T02:03:57.523" LastActivityDate="2015-06-14T02:03:57.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15774" PostTypeId="2" ParentId="15772" CreationDate="2015-06-14T02:01:40.407" Score="4" Body="&lt;p&gt;Aircraft weight and balance is done the same for all aircraft (at lest all GA aircraft as far as I know). &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/FAA-H-8083-1A.pdf&quot; rel=&quot;nofollow&quot;&gt;This PDF from the FAA&lt;/a&gt; provides a nice overview of it. You will need a few of the constants out of the &lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow&quot;&gt;POH for your plane&lt;/a&gt; such as dry weight and moments for various things. As well as specifics from your airplane is other avionics have been installed. Other than that &lt;a href=&quot;http://www.free-online-private-pilot-ground-school.com/weight_and_balance.html&quot; rel=&quot;nofollow&quot;&gt;this walkthrough&lt;/a&gt; covers it pretty well. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-14T02:01:40.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15775" PostTypeId="1" AcceptedAnswerId="15782" CreationDate="2015-06-14T03:21:24.177" Score="5" ViewCount="960" Body="&lt;p&gt;So, in most drafting/modelling software, we have a feature called &lt;code&gt;Snap to Angle&lt;/code&gt; or &lt;code&gt;Snap to Edge&lt;/code&gt;; its function is to snap the control(cursor) to the &lt;em&gt;nearest most obvious&lt;/em&gt; angle/edge to relieve strain on operator to &lt;em&gt;carefully&lt;/em&gt; move the cursor to that exact point.&lt;br&gt;&#xA;&lt;sub&gt;If you haven't seen it try &lt;code&gt;Right Click on Desktop&lt;/code&gt; &gt; &lt;code&gt;View&lt;/code&gt; &gt; &lt;code&gt;Align Icons to Grid&lt;/code&gt; &amp;amp; then move the icons around.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now on to my question:&lt;br&gt;&#xA;When performing the maneuver &lt;strong&gt;&lt;a href=&quot;https://www.google.com/?gws_rd=ssl#q=Opposing%20knife%20edge&quot; rel=&quot;nofollow noreferrer&quot;&gt;Opposing Knife Edge&lt;/a&gt;&lt;/strong&gt; it is crucial that the roll angle (w.r.t. level) should be very close to ±90°.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/NrL8q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Especially considering the high speed (&amp;amp; probably high G-Force) situations is a feature equivalent to CAD's &lt;code&gt;Snap-to-Angle&lt;/code&gt; employed in air-show modified jets?&lt;/p&gt;&#xA;" OwnerUserId="8215" LastEditorUserId="8215" LastEditDate="2015-06-16T22:22:33.533" LastActivityDate="2016-05-02T20:36:29.700" Title="Do Blue Angels jets have a snap-to-angle feature in their control sticks?" Tags="&lt;flight-training&gt;&lt;flight-controls&gt;&lt;flight-planning&gt;&lt;airshow&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15776" PostTypeId="2" ParentId="15728" CreationDate="2015-06-14T05:19:52.827" Score="31" Body="&lt;p&gt;ETOPS stands for &lt;strong&gt;E&lt;/strong&gt;xtended-range &lt;strong&gt;T&lt;/strong&gt;win-engine &lt;strong&gt;O&lt;/strong&gt;perational &lt;strong&gt;P&lt;/strong&gt;erformance &lt;strong&gt;S&lt;/strong&gt;tandards, a rule which permits twin engine aircrafts to fly routes which, at some point, is more than 60 minutes flying time away from the nearest airport suitable for emergency landing. ETOPS may also be interpreted as &lt;em&gt;Engines Turn or Passengers Swim&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;p&gt;It is not a rule which applies after an engine has failed. Rather, it is a set of regulations and standards which must be met if an airliner wishes to fly its planes more than 60 minutes away from a suitable emergency airport.&lt;/p&gt;&#xA;&lt;h2&gt;History&lt;/h2&gt;&#xA;&lt;p&gt;Early combustion engines were noticeably unreliable. It was not uncommon for a 4-engine piston aircraft to arrive at its destination with only 3 engines running. Twin engine aircrafts, as a result, were required to fly dogleg paths to stay close enough to an adequate airport.&lt;/p&gt;&#xA;&lt;p&gt;Aircrafts with more than 2 engines were not restricted by this rule. Thus, many transatlantic flights were flown with Boeing 747s and L-1011s, since airliners can fly a more direct route with these aircrafts.&lt;/p&gt;&#xA;&lt;p&gt;As engineers gained more experience in jets, they slowly recognized that jet engines are much more reliable than their piston counterparts. The FAA began to approve flying twin engines 120 minutes away from a suitable airport. This made twin engine aircrafts popular, because the fuel efficiency of flying a twin is much better than flying a 4-engine 747 or A340.&lt;/p&gt;&#xA;&lt;h2&gt;Certification&lt;/h2&gt;&#xA;&lt;p&gt;ETOPS certification requires both the &lt;strong&gt;aircraft&lt;/strong&gt; and the &lt;strong&gt;airline&lt;/strong&gt; to comply with a set of standards.&lt;/p&gt;&#xA;&lt;p&gt;For the aircraft, the manufacturer must demonstrate that flying with only one engine is relatively easy for the flight crew, safe for the airframe, and an extremely remote event.&lt;/p&gt;&#xA;&lt;p&gt;The airline must demonstrate that its flight crew training and maintenance procedures are up to a higher standard. Pilots, engineers and staff must be specially qualified for ETOPS.&lt;/p&gt;&#xA;&lt;p&gt;Recently, more operators are adopting the ETOPS approach to non-ETOPs routes. They discovered that the approach offers significant improvements in reliability, performance and dispatch rates. The cost of application is later offset by reduced maintenance costs, and costs associated with diversions, delays and turn backs.&lt;/p&gt;&#xA;&lt;h2&gt;Flight Plan&lt;/h2&gt;&#xA;&lt;p&gt;An ETOPS flight plan may look something like this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/y0XkS.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Let's say the aircraft's ground speed (with one engine inoperative!) is 450 knots. By drawing circles with radius 450nm around alternate airports, we can obtain areas which the flight must stay within. The flight path always stays inside one of these circles. If we are operating under ETOPS 120, we will draw the circles at 900nm.&lt;/p&gt;&#xA;&lt;p&gt;Actual flight plans are slightly more complex, since winds aloft (sometimes more than 100 knots) will affect the aircraft's ground speed. Dispatchers use software to calculate a route, taking aircraft weight, fuel consumption and winds into consideration.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-14T12:25:11.423" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15777" PostTypeId="2" ParentId="15771" CreationDate="2015-06-14T07:18:22.090" Score="5" Body="&lt;p&gt;If the airflow is parallel to the axis of rotation of a propeller, the resulting thrust force will also be parallel to the axis of rotation and act on the center of the propeller disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, however, the airflow hits the propeller at an angle of less than 90°, the resulting force will tilt towards the flow direction and shift away from the center of the propeller disc in a direction orthogonal to the directional change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: You fly in a single-engined plane, the two-bladed prop is spinning clockwise when seen from the pilot's view and you push the left pedal such that the aircraft flies in a sideslip. If both propeller blades are level, nothing much changes, but if the propeller turns another 90°, both blades will see very different flow conditions (see the sketch below):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8q7KB.png&quot; alt=&quot;flow speeds at propeller blades in sideslip&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the upper blade, which moves from left to right, the sum of circumferential speed ($\omega\cdot r_{Prop}$, red) and air speed ($v_{\infty}$, blue) is bigger than that of the lower blade (black arrows) and hits the blade at a larger effective angle of attack $\alpha_{eff}$. Thus, the lift force created by the upper blade is much bigger, and as a result it will act at a point on the upper half of the propeller disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same happens when the plane flies at a high angle of attack and high power (ground run of a taildragger, or climb) and the airflow hits the propeller disc slightly from below. Now the thrust force will move to the right and tilt slightly downward. This will cause the aircraft to  turn to the left and must be compensated with right rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This effect is sometimes called p-factor, but this is not a factor in an equation, but something you need to factor in when flying at high angle of attack. Note that the rotational component of the prop wash will cause a similar effect when it hits the rudder at an angle, adding to the leftward tendency of the plane.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-14T07:33:20.323" LastActivityDate="2015-06-14T07:33:20.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15778" PostTypeId="2" ParentId="15680" CreationDate="2015-06-14T08:07:55.173" Score="4" Body="&lt;p&gt;By having a spring element and a damping element - some small planes use use leaf or tubular legs bending to act as springs, other use rubber bungy cords, others use, like bigger aircraft commonly do, a gas strut damped by liquid viscosity. The damping in the puddle jumpers is the scrub of the tyres moving laterally on the runway as the suspension moves up and down. Shimmy damping in the nose gears can be either by elements providing viscous damping or coulomb/friction damping.&lt;/p&gt;&#xA;" OwnerUserId="7487" LastActivityDate="2015-06-14T08:07:55.173" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15779" PostTypeId="1" AcceptedAnswerId="15781" CreationDate="2015-06-14T09:23:11.477" Score="58" ViewCount="15473" Body="&lt;p&gt;Why are the windows of an airplane usually rounded at the edges? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nb1ZZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="14197" LastEditDate="2019-06-25T17:41:57.350" LastActivityDate="2019-06-25T17:41:57.350" Title="Why do airplanes have rounded windows?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="15780" PostTypeId="2" ParentId="15779" CreationDate="2015-06-14T09:36:47.453" Score="45" Body="&lt;h1&gt;Stress Distribution / Stress Concentration&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The sharper you make a corner, the higher the stress will be. This is undesirable since it will increase the stress on the material and can promote fatigue which can lead to structural failure down the road.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can avoid this problem by having a greater curve radius. This does not only apply to windows, but cabin/cargo doors as well on an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TX0ZF.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TX0ZF.gif&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.afgrow.net/applications/DTDHandbook/examples/page2_1.aspx&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aircraft undergo conversions become freighters and add cargo doors, you will notice that they need to make the metal thicker around the door to help distribute stress, hence the area of unpainted metal:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yYiZQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yYiZQ.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.transportarchive.org.uk/aimages/G3412.jpg&quot; rel=&quot;noreferrer&quot;&gt;transportarchive.org.uk&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.transportarchive.org.uk/aimages/G3412.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Calculation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ewp.rpi.edu/hartford/~ernesto/Su2012/EP/MaterialsforStudents/Aiello/Roark-Ch06.pdf&quot; rel=&quot;noreferrer&quot;&gt;Some material&lt;/a&gt; on this, although it make the simplification the stress is only in one direction rather than both as in real life. You can see how as &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt; becomes smaller the stress concentration &lt;span class=&quot;math-container&quot;&gt;$K_t$&lt;/span&gt; goes up, raising the maximum stress (&lt;span class=&quot;math-container&quot;&gt;$\sigma_{max}$&lt;/span&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F4t9K.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Footnote: There will have to be a little bit of 'play' between the window and fuselage for technical reasons, such as thermal and pressure expansion, making this type of arrangement necessary. If you could perfectly carry over the load in every direction to the window this would not be necessary.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-29T09:16:12.437" LastActivityDate="2019-03-29T09:16:12.437" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15781" PostTypeId="2" ParentId="15779" CreationDate="2015-06-14T09:37:56.047" Score="71" Body="&lt;p&gt;A pressurized fuselage needs rounded corners at all cut-outs to avoid the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stress_concentration&quot;&gt;accumulation of stress in corners&lt;/a&gt;. If the corners were not rounded, the fuselage skin would need to be locally reinforced, or it would begin to crack there soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was &lt;a href=&quot;http://www.extremetech.com/extreme/129764-tech-wrecks-lessons-from-some-of-the-biggest-hardware-screw-ups/3&quot;&gt;learned the hard way&lt;/a&gt; by de Havilland, when their &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot;&gt;Comet jet airliner&lt;/a&gt; began to plunge out of the sky for unknown reasons. In one of the first major crash investigations in aviation history, the wreck of one was &lt;a href=&quot;https://en.wikipedia.org/wiki/BOAC_Flight_781&quot;&gt;lifted from the seafloor off Elba and re-assembled&lt;/a&gt;. Then it was learned that the pressurized cabin had burst from cracks emanating from the window corners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/epoOh.jpg&quot; alt=&quot;de Havilland Comet&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;de Havilland Comet I. Note the square windows. The window which caused the destruction of G-ALYP was on top of the fuselage and cannot be seen in this picture. (Picture &lt;a href=&quot;http://www.extremetech.com/extreme/129764-tech-wrecks-lessons-from-some-of-the-biggest-hardware-screw-ups/3&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jLomg.jpg&quot; alt=&quot;Color coded stress plot in a fuselage panel with window cutout&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finite element simulation of corner stresses in a Comet fuselage skin.  Red denotes the highest stresses. (Picture &lt;a href=&quot;http://personal.egr.uri.edu/sadd/compclassroom/fea.html&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_49&quot;&gt;Other aircraft companies&lt;/a&gt; had built pressurized cockpits twenty years earlier and did it right the first time …&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-14T10:13:12.410" LastActivityDate="2015-06-14T10:13:12.410" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15782" PostTypeId="2" ParentId="15775" CreationDate="2015-06-14T10:04:22.627" Score="16" Body="&lt;p&gt;Short answer: No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: No way!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be a feature which pilots would never accept and for good reasons.&lt;br&gt;&#xA;There are many instances where you want to fly at a slight angle to exactly horizontal or vertical to make corrections. Just think of flying an approach with crosswind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The designers have made the cockpit glazing transparent to enable the pilot to check and adjust his/her attitude, and this feature works really well. There is no need to add something which will be in the way of proper flying at some times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you do find sometimes on small aircraft with manual controls, however, is a trailing edge modification which helps with centering the rudder and/or the ailerons. See below for an example: This is the tail of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Klemm_Kl_35&quot; rel=&quot;nofollow noreferrer&quot;&gt;Klemm 35&lt;/a&gt;, and the rudder has two narrow strips which are deflected slightly to the left and the right, respectively. This increases the force gradient over deflection for the first few degrees when the rudder is moved away from its centered position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/tdj0a.png&quot; alt=&quot;Klemm 35 tail detail&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Klemm 35 tail detail (own work)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-02T20:36:29.700" LastActivityDate="2016-05-02T20:36:29.700" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15783" PostTypeId="1" AcceptedAnswerId="15838" CreationDate="2015-06-14T10:40:10.607" Score="6" ViewCount="3188" Body="&lt;p&gt;&lt;em&gt;This is a follow-up to my previous question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/15728/what-is-etops-and-how-does-it-work&quot;&gt;What is ETOPS and how does it work?&lt;/a&gt; &#xA;There is a related question &lt;a href=&quot;https://aviation.stackexchange.com/questions/8462/are-four-engined-airplanes-subject-to-etops-equivalent-rules&quot;&gt;here&lt;/a&gt;, but it does not specifically answer this new question.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Facts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Since February 2015, all new aircraft are required to get ETOPS&#xA;approval to fly ETOPS 180+ routes. &lt;a href=&quot;http://boeing.mediaroom.com/2015-03-18-Boeing-747-8-Intercontinental-Receives-FAA-Approval-for-330-Minute-ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The 747-8 has ETOPS 330. The 787 has ETOPS 330. The A350 has ETOPS&#xA;370.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why does ETOPS not apply to the 747-400?&lt;/p&gt;&#xA;" OwnerUserId="8818" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-06-15T19:35:14.543" Title="Why does ETOPS not apply to older 4 engine aircraft?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;aircraft-certification&gt;&lt;boeing-747&gt;&lt;etops&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15784" PostTypeId="2" ParentId="15691" CreationDate="2015-06-14T12:45:32.280" Score="6" Body="&lt;p&gt;Concur with the other commenters that there are advantages to squawking 7700 at the appropriate time in the aviate, communicate, navigate steps. There is one situation not mentioned so far in which it might be especially important: when an emergency occurs after loss of communications for an IFR flight in IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an IFR flight loses communications while in VMC, the pilot is supposed to continue the flight under VFR and land as soon as practical (FAR 91.185). So if there is good weather out, and you set your transponder to 7600 and deviate from your IFR clearance by turning towards an airport at which you're going to land, ATC has a pretty good idea of what you're going to do and can act appropriately. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what if you're in IMC? If you set your transponder to 7600 and proceed in accordance with the IFR lost-comm procedures, ATC will assume that you're going to continue to proceed in accordance with them (route assigned, vectored, expected, or filed; altitude highest of the minimum IFR altitude, expected altitude, or assigned altitude). But what if a different emergency occurs at that point and you need to deviate from that plan? If you then squawk 7700, ATC will know that you are deviating not because you're in VMC and continuing under VFR, but because you have an emergency and are exercising your PIC authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What good is that when ATC can't talk to you? I'd much rather ATC send emergency assistance to whatever airport I'm headed for or wherever I disappeared from their radar scope rather than waiting for me to call them on the ground. And it certainly helps that they're going to clear the skies of all traffic anywhere near me. Obviously if you have your hands full flying the plane then setting the transponder isn't a priority, but it does offer you considerable advantages if you have the time to do so.&lt;/p&gt;&#xA;" OwnerUserId="8856" LastActivityDate="2015-06-14T12:45:32.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15786" PostTypeId="1" AcceptedAnswerId="15814" CreationDate="2015-06-14T13:53:38.073" Score="14" ViewCount="3937" Body="&lt;p&gt;I read the following on &lt;a href=&quot;http://www.flightradar24.com/how-it-works&quot; rel=&quot;noreferrer&quot;&gt;Flightradar24.com&lt;/a&gt;'s 'How it works' page.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The percentage of aircraft equipped with ADS-B receivers is steadily&#xA;increasing though, as they will become mandatory for most aircraft&#xA;around the world by 2020. When mandatory, ADS-B will replace primary&#xA;radar as the primary surveillance method used by ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Sure, that sounds lovely, but it it seems to me that a large portion of aircraft do not actually use GPS, but instead rely on inertial navigation systems or similar. Of course, the ATC doesn't need millimeter precision, or even an accurate position within a kilometer, but whenever I check flightradar24, there is quite a large bunch of airplanes reporting their position with offsets up to a few kilometers - if I were to judge by the ADS-B data, I would report a major emergency every few minutes.&lt;/p&gt;&#xA;&lt;p&gt;How will ADS-B actually reliably replace primary radar? Will GPS have become mandatory by 2020? Or is Flightradar24.com just being optimistic?&lt;/p&gt;&#xA;&lt;p&gt;(Side note: I know that redundancy is very popular in the aviation world, but I don't think you can call something 'replaced' when primary radar is still used for a large portion of the flights)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: some parts of some answers seem to be concentrating on update rate / transmission losses and errors. For clarification, I included a screenshot (which I could literally take the second I looked at fr24.com, indicating how often this happens).&#xA;&lt;img src=&quot;https://i.stack.imgur.com/DzqHJ.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;At the time this picture was taken, the 36R runway was in use for landing ('yellow' aircraft top right just landed). The selected aircraft is however happily taxiing in a field (pattern matching 36R's adjacent taxiways). This is not caused by update rate or transmission losses (i.e., this can't be old information, the plane was never in that field). Transmission error also seems out of the question, since the entire track is a smooth line (errors sometimes do happen, but are not 'hidden' on fr24 - a large 'jump' in the track can be seen sometimes). So either the plane is reporting a 'wrong' position (how is this handled by ATC?) or fr24 somehow messes up the data (how is that possible?&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-02-09T00:38:09.700" Title="How can ADS-B replace primary radar when FlightRadar24, using ADS-B, is so inaccurate?" Tags="&lt;air-traffic-control&gt;&lt;ads-b&gt;" AnswerCount="6" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15787" PostTypeId="2" ParentId="15786" CreationDate="2015-06-14T14:14:42.473" Score="4" Body="&lt;p&gt;The linked page &lt;em&gt;also&lt;/em&gt; states that as part of ADS-B,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft gets its location from a GPS navigation source (satellite)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This strongly suggests that any aircraft using INS position only (perhaps with DME/DME updates only at present) would be required to add a GPS receiver as part of the ADS-B upgrade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While no installed + approved + certified aviation equipment will &lt;em&gt;ever&lt;/em&gt; be as cheap as a basic handheld Garmin from your local sporting goods store, the big cost of ADS-B seems likely to be from things other than the GPS piece of it. In E-GPWS systems, the GPS receiver can be dedicated to just that system, without incurring costs of integrating it into the FMC, so it may be possible to do likewise with ADS-B.  This would probably reduce costs somewhat, although I don't know how long INS/DME RNAV will be allowed, given the move toward &quot;Next-Gen&quot; everything in ATC.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-14T14:14:42.473" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15788" PostTypeId="2" ParentId="15775" CreationDate="2015-06-14T14:42:34.127" Score="6" Body="&lt;p&gt;In addition to Peter's great answer...  In the Viper, the stick only moves ~1/4 inch.  With this little movement, there's not really room built in to be able to offer this &quot;feature&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some jets do, however, have different stick characteristics.  For example, the first 1/2 of stick movement may be responsible for 3/4 control surface deflection (so it's not linear).  Another example may be that the last 1/4 of stick deflection experiences greater force to prevent over Gs or avoid breaking an ops limit.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-14T14:42:34.127" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15789" PostTypeId="2" ParentId="15684" CreationDate="2015-06-14T15:35:28.347" Score="12" Body="&lt;p&gt;No, rocket missiles are recoil-less weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When firing a gun, the charge burns inside the chamber and the generated gasses do not escape before the shell leaves the barrel, so the reaction force is transferred to the body of the gun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When firing a rocket missile however there is open space behind he missile and the reaction force only accelerates the generated gasses that are ejected off the back and does not affect the launching platform significantly. This is true for missiles launched from tube (like &lt;a href=&quot;https://en.wikipedia.org/wiki/Bazooka&quot;&gt;Bazooka&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/BGM-71_TOW&quot;&gt;TOW&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydra_70&quot;&gt;Hydra 70&lt;/a&gt;), off a rail like the wing-tip sidewinders or from free fall like most of the heavier air-launched rockets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lack of recoil is an important advantage of rockets. Bazooka can be fired from shoulder while anti-tank gun with comparable explosive charge is heavy device and needs good support to handle the recoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand rockets need more propellant than comparable gun shells, because the generated gasses leaving at high speed carry away a lot of kinetic energy most of which would be available for the shell in a gun.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-14T15:35:28.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15791" PostTypeId="1" AcceptedAnswerId="15794" CreationDate="2015-06-14T16:42:37.113" Score="21" ViewCount="4775" Body="&lt;p&gt;As per subject has anyone flown an airliner (737, A319 etc etc or bigger) solo? (meaning only 1 pilot alone with no passengers?) Tried to google search but did not find any reference. Question applies to any of modern airliners era with and without flight engineer.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="7532" LastEditDate="2015-06-14T19:27:10.120" LastActivityDate="2020-08-05T08:47:49.213" Title="Have there been any solo flights on airliners?" Tags="&lt;airliner&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15792" PostTypeId="2" ParentId="15791" CreationDate="2015-06-14T16:48:21.697" Score="7" Body="&lt;p&gt;Airplanes are certified to be operated with a particular amount of crew. From a regulation standpoint there are &lt;a href=&quot;http://www.flyingmag.com/single-pilot-jets&quot;&gt;jets certified for single pilot operations&lt;/a&gt; but they tend to be on the smaller size (Citation Mustang comes to mind). That being said I cant say that these planes have never been flown in a single pilot situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/EASA-TCDS-A.120_(IM)_Boeing_737-09-12072012.pdf&quot;&gt;EU EASA document&lt;/a&gt; states that the minimum crew for a 737 is two &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;18&quot;&gt;&#xA;  &lt;li&gt;Minimum Flight Crew: Two (2): Pilot and Co-pilot, for all types of flight&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/9dd07e4b4293722e86257dfc006774ca/$FILE/A16WE_Rev_54.pdf&quot;&gt;US type cert for the 737&lt;/a&gt; says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Minimum Crew for All Flights: 2 (Pilot and Copilot)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which applies to all the following 737 models &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DATA PERTINENT TO MODELS 737 Original Series -100, -200, -200C and 737 Classic Series -300, -400, -500:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you could not do it in any kind of regular situation. It is possible that some of the planes were test flown with only a single pilot but I dont know for sure. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-14T16:54:15.230" LastActivityDate="2015-06-14T16:54:15.230" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15794" PostTypeId="2" ParentId="15791" CreationDate="2015-06-14T19:13:03.803" Score="21" Body="&lt;p&gt;In normal operations there are regulations against this sort of thing (as Dave has said).  But there have been a few emergencies where the First Office or the Captain have become incapacitated (due to medical emergencies), and the remaining pilot has declined to ask if there is another pilot on board to help fly the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example from 2011 of a &lt;a href=&quot;http://www.skybrary.aero/index.php/B738,_en-route,_south_east_of_Marseilles_France,_2011&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ryanair flight having this occur&lt;/a&gt;**, I have heard of others but can't find references.  So, admittedly, that may be the only actual occurrence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to finally answer your questions:  Very rarely, in an emergency situation, there can be a single pilot on a commercial airliner.  Granted, there were passengers on board, so I'm not sure it fits your narrow definition of &quot;solo&quot;, but it's about as close as it's going to get.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For completeness (though I don't think it counts), there have been a few instances of a single pilot stealing a commercial jetliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example &lt;a href=&quot;https://en.wikipedia.org/wiki/2003_Boeing_727-223_disappearance&quot; rel=&quot;nofollow noreferrer&quot;&gt;this 727&lt;/a&gt;.  There were actually two people involved, one was a mechanic, the other had a private pilots license (hence the pilot was &quot;soloing&quot;).  The aircraft has not been seen since...so it's assumed it ended badly, and, for the record, it's also assumed the pilot was coerced (if indeed he was even flying the plane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a couple more incidents, namely this &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19940713-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antonov-26&lt;/a&gt;, which was stolen by a mechanic, circled for an hour, then crashed.  And also this &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19991011-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATR-42-320&lt;/a&gt;, which was actually stolen by a Captain form Air Botswana.  He circled the airport for a couple of hours demanding to speak to everyone from his girlfriend, to his boss to the President of Botswana.  They were actually arranging to have him speak with the president when he crashed his plane into two other Air Botswana ATR-42-320s that were parked on the ground.  He was the only one killed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, though, I'm not sure if these fit the criteria you are looking for.  But in that last one, at very least, he was the only person on board the aircraft, it was a commercial aircraft and he was in fact a Captain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But to say all this an irregularity would be an extreme understatement...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;** For clarification:  The reason I state this is the only example I could find is because it's the only one where I could find a report where it was specifically stated the remaining pilot had no help.  To quote from the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Once the initial Cabin Crew assistance was complete, the Captain indicated that he did not need assistance in operating the aircraft, although this was suggested in the operator’s procedures for pilot incapacitation. The First Officer took no further part in the operation of the aircraft. No inquiries as to the possible presence on board the aircraft of either medically trained personnel or qualified pilots were made.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;All other examples I saw either specifically stated that a new co-pilot was found, or they skipped that detail entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of that being said, I somehow doubt this is the only case, it's just the only one I could explicitly verify.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2017-09-21T14:21:53.180" LastActivityDate="2017-09-21T14:21:53.180" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="15795" PostTypeId="2" ParentId="15791" CreationDate="2015-06-14T21:14:23.737" Score="13" Body="&lt;p&gt;One more example of a single pilot for at least part of the flight:  Discovery Channel did a special that involved actually crashing a jetliner.  I do not recall the crew configuration at takeoff but I do recall that the bailout was handled in two stages, the pilot only going once everyone else was away.  The plane was being flown by remote control once he abandoned the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This did &lt;strong&gt;not&lt;/strong&gt; happen in the USA, as others have said it would be illegal.  Mexico allowed it with restrictions, though.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-06-14T21:14:23.737" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15796" PostTypeId="1" CreationDate="2015-06-14T21:25:11.000" Score="11" ViewCount="468" Body="&lt;p&gt;When looking up some information for the recent question &lt;a href=&quot;https://aviation.stackexchange.com/q/15791/755&quot;&gt;Have there been any solo flights on airliners?&lt;/a&gt;, I found &lt;a href=&quot;http://www.airsafenews.com/2013/09/united-airlines-captain-dies-after.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt; that lists several incidents in which a pilot has become incapacitated in flight. One thing that I found particularly surprising was that, in two of the six specific incidents they mention, the person who helped the remaining pilot for the remainder of the flight was actually a flight attendant who had a pilot certificate. This then made me wonder:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How common is it for an airline flight attendant to also be a certificated pilot?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-06-15T03:50:52.197" Title="How common is it for flight attendants to have pilot certificates?" Tags="&lt;flight-attendant&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15797" PostTypeId="1" CreationDate="2015-06-14T21:53:24.557" Score="4" ViewCount="430" Body="&lt;p&gt;&lt;a href=&quot;http://www.bazl.admin.ch/experten/00002/index.html?lang=de&amp;amp;download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1acy4Zn4Z2qZpnO2Yuq2Z6gpJCDfIR6gmym162epYbg2c_JjKbNoKSn6A--&quot; rel=&quot;nofollow&quot;&gt;ICAO Annex 14&lt;/a&gt; recommends that &quot;&lt;em&gt;Runway centre line lights shall be provided on a runway intended to be used for take-off with an operating minimum of an RVR of the order of 400 m or higher when used by aeroplanes with a very high take-off speed, particularly where the width between the runway edge lights is greater than 50 m.&lt;/em&gt;&quot; (section 5.3.12.4).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wish to know whether aircraft are categorized by take-off speed (like they are by approach speed), or which aircraft fall in the category of having very high take-off speed.&lt;/p&gt;&#xA;" OwnerUserId="8866" LastEditorUserId="19" LastEditDate="2016-07-04T11:17:23.253" LastActivityDate="2016-07-04T11:17:23.253" Title="Is there a Take-off speed category?" Tags="&lt;takeoff&gt;&lt;icao-sarps&gt;&lt;transport-category&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15798" PostTypeId="1" CreationDate="2015-06-14T23:03:29.690" Score="1" ViewCount="124" Body="&lt;p&gt;Can we scale up from the A380 airbus to accommodate more passengers&lt;/p&gt;&#xA;" OwnerUserId="8868" LastActivityDate="2015-06-14T23:03:29.690" Title="Can we build a bigger aircraft than the A380" Tags="&lt;aircraft-design&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2015-06-15T01:00:48.093" ContentLicense="CC BY-SA 3.0" />
  <row Id="15799" PostTypeId="2" ParentId="15797" CreationDate="2015-06-14T23:56:04.353" Score="2" Body="&lt;p&gt;Never heard of any sort of takeoff speed &quot;category&quot; applied to operators in US rules, but we do have rules (in an airline's OpSpecs) for &lt;em&gt;our&lt;/em&gt; aircraft that tell us at what min visibility centerline lights are required for takeoff (and landing as well).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airport were considering investing in Centerline Lights, that recommendation, combined with a little research into the requirements of the airlines who'd potentially operate into &amp;amp; out of that runway, would provide a basis to determine what incremental gain in utilization the runway could have. (Along with some meterology hisoric data -- numbers of hours/days at or below a given RVR value.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term &lt;code&gt;very high take-off speed&lt;/code&gt; does seem a little nebulous; airliners' takeoff speeds are pretty high compared with most General Aviation aircraft, and unless you're building a runway for fighter or experimental jets, there aren't that many aircraft with higher takeoff speeds than we have that it would seem worthwhile to install CL just for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, who knows... Maybe another ICAO document does define that term somewhere.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-14T23:56:04.353" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15800" PostTypeId="1" AcceptedAnswerId="15802" CreationDate="2015-06-15T00:02:50.593" Score="16" ViewCount="5159" Body="&lt;p&gt;This photo of &lt;a href=&quot;http://www.mirror.co.uk/news/world-news/allegiant-air-flight-330-astonishing-5881183?ICID=FB_mirror_main&quot; rel=&quot;nofollow noreferrer&quot;&gt;Allegiant Air flight 331&lt;/a&gt; got me wondering: how much weight would a typical airliner's wings be able to hold?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SaZal.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Aside:&lt;/em&gt; Apparently these folks didn't realise that if they smell gas in the cabin, they probably shouldn't decide to go out of the emergency exits and stand ON TOP OF ITS TANKS! God forbid one of them gets nervous and lights a smoke!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is basically: how much weight are airliner wings required to hold $\div$ the average passenger weight? Theoretically how many people? :)&lt;/p&gt;&#xA;" OwnerUserId="97" LastActivityDate="2016-08-26T03:13:32.083" Title="How many people can stand on airliner's wings?" Tags="&lt;airliner&gt;&lt;passenger&gt;&lt;wing&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="15801" PostTypeId="2" ParentId="15763" CreationDate="2015-06-15T00:22:09.140" Score="8" Body="&lt;p&gt;It should be noted that some civilian aircraft do have military systems fitted (and not just radars like AWACS). &lt;a href=&quot;http://defense-update.com/20110621_c-music.html&quot;&gt;The Israeli airline has a laser-based missile defense system fitted to its airliners.&lt;/a&gt; (They wanted to use flares but apparently you can't drop flares at a commerical airport due to fire risk, so they got a laser-based system instead).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The package is slightly different from the one sold to the miltiary as it has to be completely self-contained: it can't use the interfaces - for example to the missile warning systems - on a warplane as the airliners don't have them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were going to use bombs I suspect you might roll them out of the back of a cargo plane. During the Falklands War (1980s) there was some talk about Argentina possibly attempting it, but I don't think they ever did.&lt;/p&gt;&#xA;" OwnerDisplayName="user8869" LastActivityDate="2015-06-15T00:22:09.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15802" PostTypeId="2" ParentId="15800" CreationDate="2015-06-15T00:25:11.177" Score="23" Body="&lt;p&gt;Disregarding the fact that the wing load vector on a passenger jet usually points &lt;em&gt;up&lt;/em&gt;, not &lt;em&gt;down&lt;/em&gt;, the wings will usually bear most of the load for the &lt;em&gt;entire aircraft&lt;/em&gt;. The &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_MD-80#Specifications&quot;&gt;MTOW for an MD-80 is 63,500 kg&lt;/a&gt;. If an &quot;average&quot; passenger is 80 kg, then that is 800 passengers. Obviously that is going to be greater than the number of passengers on the flight, because those wings had already lifted those passengers (and the rest of the plane) into the air in the first place.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-06-15T00:25:11.177" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15803" PostTypeId="2" ParentId="15800" CreationDate="2015-06-15T00:39:21.260" Score="10" Body="&lt;p&gt;Each aircraft has its own design for how much it weight it has to hold on the wing. This is incorporated when an airliner goes through certification (I believe it needs to carry 3 times it's design load for 5 seconds, but I may be wrong in that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airplanes are required to hold lots of weight on the wings, not only from the forces of flight, but also by the possibility of evacuations. According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot;&gt;Wikipedia&lt;/a&gt;, aircraft such as the Boeing 747 can hold 740 kg/m2. With a wing area of 525 m2, this means that the wings can hold 388 500 kg. Assuming each passenger is about 100 kilograms, that means you can hold 3885 people on the wing at once. That is, of course, if you can manage to fit them all in that gaggle without slipping off. It'd be pretty tough getting 5 people in a square metre, would it not?&lt;/p&gt;&#xA;" OwnerUserId="7670" LastEditorUserId="7670" LastEditDate="2015-06-15T01:58:33.190" LastActivityDate="2015-06-15T01:58:33.190" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15804" PostTypeId="2" ParentId="15800" CreationDate="2015-06-15T00:48:13.037" Score="12" Body="&lt;p&gt;The specific numbers will vary by aircraft type and model, but from an empty dry wing, you can add thousands of pounds of fuel to each wing. Then on a winter night, add several pounds of ice/snow to every square foot of the wing's surface, which can easily remain there for hours or days.  Granted, this is all weight that is on the wing rather than on the fuselage, but as was pointed out, these wings support over 50 tons of aircraft weight at cruise and can handle over double that at a sustained G load, so these are pretty stout structures. A couple dozen people just isn't that big a load for a structure that can handle loads WELL over an order of magnitude greater on a fairly routine basis.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-15T00:48:13.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15805" PostTypeId="2" ParentId="3838" CreationDate="2015-06-15T03:03:33.313" Score="2" Body="&lt;p&gt;The Rockwell HGS doesn't need enhanced or synthetic vision for takeoffs as low as 300' RVR on approved runways. With suitable runway lights, even the HGS isn't required for takeoffs as low as 500' RVR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearly you'd need a takeoff alternate in either case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have VERY limited cues with visibility that low, but less is required to fly off of the runway than is needed to land on it, so it is approved and even somewhat routine in places like Salt Lake City and Seattle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what IS the takeoff guidance system, or in Rockwell vocabulary, a Head-up Guidance System? It is a HUD very much like in a fighter, with all primary flight instrumentation and guidance visible directly in front of the pilot, so the runway lights and the localizer guidance are superimposed, and the latter is visible even if a dense patch of fog obscures the former.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With enhanced vision, an IR picture from a camera mounted near the HUD is superimposed as well, and depending on the capabilities of the IR, you may never be in weather below Cat I again!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Added: &lt;a href=&quot;https://m.youtube.com/watch?v=1cwsuSQ-nVs&quot; rel=&quot;nofollow&quot;&gt;Rockwell HGS promo video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Added: &lt;a href=&quot;https://m.youtube.com/watch?v=P9N_PFtBUOA&quot; rel=&quot;nofollow&quot;&gt;Rockwell Synthetic Vision video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Added: &lt;a href=&quot;https://m.youtube.com/watch?v=DR9lyAM2YNE&quot; rel=&quot;nofollow&quot;&gt;Gulfstream Enhanced Vision video&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-06-15T03:39:02.360" LastActivityDate="2015-06-15T03:39:02.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15806" PostTypeId="2" ParentId="15796" CreationDate="2015-06-15T03:50:52.197" Score="11" Body="&lt;p&gt;In my experience, it is uncommon but certainly not unheard of. Maybe between 1% and 5%, as a ballpark.  A flight attendant married to a pilot who owns his own aircraft has access to the plane and instruction, so that's one scenario. In another case, an F/A I flew with a few times was building time as a CFI and doing right-seat work at SimuFlight, before she left our airline to start with a regional. (Wouldn't be at all surprised if she's flying at a major right now.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among flight attendants, there are a lot of really interesting stories of how they got to be where they are. Sometimes the generalizations fit, but when they don't, you find an amazing breadth of experiences in that group.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-15T03:50:52.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15807" PostTypeId="1" AcceptedAnswerId="15809" CreationDate="2015-06-15T05:32:54.523" Score="19" ViewCount="5564" Body="&lt;p&gt;I know that we can re-fuel fighter jets mid-flight, but do we have also a mechanism to reload them with ammunition during mid-flight so they don't need to go back to base to reload?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1467" LastEditDate="2018-04-20T08:14:55.340" LastActivityDate="2019-09-17T19:11:51.293" Title="Can fighter jets be reloaded with ammunition mid-flight?" Tags="&lt;fighter&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15809" PostTypeId="2" ParentId="15807" CreationDate="2015-06-15T08:27:01.683" Score="21" Body="&lt;p&gt;Short answer: no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: you would need to design a carrier craft that could store large quantities of ammunition in safe conditions - enough to supply more than one fighter, perhaps several times. Having a lot of live ammo on board would increase the chances of something going off at a bad time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To continue: this ammunition then needs to be transferred to the fighter, while in flight at speeds of what, say 200 kts? How do we do this? Perhaps some sort of pneumatic tube would work, but only for the small stuff and you would have to make sure it would arrive safely. Transferring whole cassettes of rounds or bombs would need some other means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, so let's say we transfer the ammo with some sort of failsafe on (pins, etc.). So now the fighter pilot needs some means of removing the failsafe in order to use the stuff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the only feasible solution would be a carrier aircraft that could take the fighter on board while refuelling and rearming. That is what they built the Akron zeppelin for in the 1930s (Wikipedia link: &lt;a href=&quot;https://en.wikipedia.org/wiki/USS_Akron_%28ZRS-4%29&quot;&gt;https://en.wikipedia.org/wiki/USS_Akron_%28ZRS-4%29&lt;/a&gt;). Don't think it would be feasible with modern fighters, though. &lt;/p&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="8558" LastEditDate="2015-06-15T08:32:32.547" LastActivityDate="2015-06-15T08:32:32.547" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15810" PostTypeId="2" ParentId="15733" CreationDate="2015-06-15T08:27:32.347" Score="2" Body="&lt;p&gt;The helicopter is basically suspended from its main rotor, so you are sitting in the equivalent of a large swing/ride and pulled towards its floor.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Wuppertal_Suspension_Railway&quot; rel=&quot;nofollow&quot;&gt;Suspended monorails&lt;/a&gt; with the ability to lean into curves can likewise look precariously wobbly from the outside while appearing perfectly stable for the inside passengers who don't feel the outside forces &lt;em&gt;exactly&lt;/em&gt; because the craft is able to follow them, compensating their effect on the load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of jerk you can put on a heli by controlling the main blades is limited.  You'll probably cause more problems by switching on and off auxiliary means of propulsion.  However, those don't make for the dramatic dives, banks and turns in movies.&lt;/p&gt;&#xA;" OwnerUserId="8874" LastActivityDate="2015-06-15T08:27:32.347" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15811" PostTypeId="2" ParentId="15786" CreationDate="2015-06-15T08:28:21.420" Score="3" Body="&lt;p&gt;First of all, what you see on Flightradar24 is not the same as what air traffic controllers see. ADS-B requires a ground station. The FR24 receivers are placed sporadically in peoples homes - far from the sophistication of the proper, more powerful, ATC stations. The coverage on FR24 is often sloppy but the controllers screens are fine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B is already mandatory in Australia above FL290. As you can see &lt;a href=&quot;http://www.casa.gov.au/pilots/download/ads-b.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, ADS-B brings many benefits - none more so than on page 5 of that booklet. There is a diagram there that compares existing radar coverage to ADS-B coverage. Only a tiny bit of Australia is covered by radar. Radar is very expensive to install and maintain, and doing so in the desert cannot really be justified. But ADS-B provides virtually complete coverage of the country at cruise, perfect for the huge amount of Asia/Europe traffic. But most of this traffic will not appear on FR24 because they don't have many receivers out in the middle of nowhere. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-06-15T08:28:21.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15812" PostTypeId="1" CreationDate="2015-06-15T10:18:17.147" Score="14" ViewCount="2900" Body="&lt;p&gt;Recently I had the opportunity to take a closer look at the skydiving parachute. And I could not explain to my self the reason to use D-Bag and not pack main canopy directly in backpack compartment.&#xA;I know that the reserve canopy is packed directly into the backpack. And the sequence for deploying reserve canopy is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Sky diver pulls release cord, which pulls out the pin that holds the backpack flaps close&lt;/li&gt;&#xA;&lt;li&gt;Spring loaded drogue parachute jumps out into the airstream&lt;/li&gt;&#xA;&lt;li&gt;Drogue chute pulls out the main canopy which opens&lt;/li&gt;&#xA;&lt;li&gt;Sky diver does not flatten him or herself on the ground.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;More puzzling is the main canopy assembly. As far as I could understand the main canopy is packed into so called D-Bag. This D-Bag is then inserted into container in the main backpack. Why this intermediate step?&#xA;The deployment sequence of main canopy is described here: &lt;a href=&quot;http://adventure.howstuffworks.com/skydiving4.htm&quot; rel=&quot;nofollow&quot;&gt;http://adventure.howstuffworks.com/skydiving4.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder what happens to the D-Bag after deployment. Does it hang loose? Does it remain close to the canopy on the upper side?&#xA;As far as I understand the drogue chute remains attached on the back side of the canopy and acts as a sort of stabilizer. But what about D-Bag? Does it just flap around?&#xA;Why not pack main canopy in separate compartment of backpack directly?&lt;/p&gt;&#xA;" OwnerUserId="8877" LastEditorUserId="8877" LastEditDate="2015-06-16T18:11:07.970" LastActivityDate="2015-06-16T18:11:07.970" Title="What is the purpose of D-Bag in skydiving parachute?" Tags="&lt;skydiving&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15813" PostTypeId="1" CreationDate="2015-06-15T10:20:18.380" Score="35" ViewCount="12362" Body="&lt;p&gt;From another &lt;a href=&quot;https://aviation.stackexchange.com/questions/15763/can-a-commercial-airliner-be-used-for-military-purposes&quot;&gt;question&lt;/a&gt; asks about the possibility of dropping bombs from converted airliners. My question: is it possible to safely fly aircraft with a door open for the whole flight envelope? Would the aerodynamics be affected if we did not close the door?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not asking about the need of oxygen for the crew, just about the aerodynamics involved. I know the plane would not be pressurized.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-18T14:08:26.023" Title="Is it possible for an airliner to safely fly with doors open?" Tags="&lt;aerodynamics&gt;&lt;airliner&gt;" AnswerCount="7" CommentCount="3" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15814" PostTypeId="2" ParentId="15786" CreationDate="2015-06-15T10:28:55.347" Score="20" Body="&lt;h2&gt;TLDR&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;How will ADS-B actually reliably replace primary radar?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It will not.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Will GPS have become mandatory by 2020?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Strictly speaking no, effectively yes.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;There are so many problems with that quote from FR24 that I don't know where to start.&lt;/p&gt;&#xA;&lt;p&gt;Let's take it apart and analyse it sentence by sentence.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The percentage of aircraft equipped with ADS-B receivers is steadily increasing though&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Totally irrelevant. An ADS-B receiver allows reception of ADS-B signals from other aircraft. These can be used for example to create a Cockpit Display of Traffic Information (CDTI) or augment TCAS. The number of aircraft with this so called ADS-B &lt;strong&gt;IN&lt;/strong&gt; is increasing, but the equipage percentage is probably below 2% at the moment.&lt;/p&gt;&#xA;&lt;p&gt;If you are concerned with using ADS-B operationally for ATC then airborne receivers are not of interest. Instead you should be looking at the transmitter side.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[&lt;em&gt;ADS-B receivers&lt;/em&gt; ...] will become mandatory for most aircraft around the world by&#xA;2020.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;ADS-B receivers are not mandatory in any foreseen regulation yet. ADS-B &lt;strong&gt;transmitters&lt;/strong&gt; are / will become mandatory in many parts of the world. The EU and USA rules mandate ADS-B in 2020.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When mandatory, ADS-B will replace primary radar&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;ADS-B is not intended to replace primary radar. As a new addition to the surveillance technology mix, it will not replace any other technology in the short term.&lt;/p&gt;&#xA;&lt;p&gt;ADS-B is a form of cooperative surveillance, meaning that the aircraft or vehicle that is supposed to be tracked needs to cooperate by transmitting the ADS-B signal. Primary Surveillance Radar (PSR) on the other hand is a non-cooperative surveillance technology; it works by detecting signals reflecting off the target of interest. PSR can detect aircraft that do not transmit any signals. Since PSR and ADS-B are fundamentally different in their working, they have fundamentally different use cases. ADS-B will not replace primary radar and never was intended to.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;will replace primary radar as the primary surveillance method used by ATC&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Primary Surveillance Radar is not the primary surveillance method used by ATC in many parts of the world. Since PSR only gives azimuth and range measurements essential information like aircraft identification and altitude is missing. Therefore Secondary Surveillance Radar (SSR) is the primary surveillance method used for ATC since it provides altitude and identity in addition to azimuth and range measurements.&lt;/p&gt;&#xA;&lt;p&gt;Secondary radar, like ADS-B is a form of cooperative surveillance; it relies on the aircraft replying to an interrogation from the radar. ADS-B can and will replace a number of secondary radars, but not all of them.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Now for the rest of your question.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;it seems to me that a large portion of aircraft do not actually use GPS, but instead rely on inertial navigation systems or similar.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Indeed a large number of aircraft do transmit their position on ADS-B that is based on a non-GPS source, usually from the INS. INS can not provide the accuracy and integrity that GPS can provide and therefore you see large position errors on FR24. The fact that the position is not to be trusted is reported in the ADS-B message in the quality indicators, but unfortunately FR24 doesn't use this information.&lt;/p&gt;&#xA;&lt;p&gt;All the ADS-B mandates require that the system is able to provide high integrity data, which effectively means that GPS is required as position source, although theoretically other means are possible as well. Therefore in 2020 all aircraft subject to the various ADS-B regulations will have to be GPS equipped.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Of course, the ATC doesn't need millimeter precision, or even an&#xA;accurate position within a kilometer,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;ATC does not need millimeter precision (GPS wouldn't provide that anyway) but they do need position accuracy within a kilometre and sometimes within about 10 meters (e.g. runway entry stop bar monitoring). ADS-B  with appropriate GPS source will be able to provide that.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-03-27T09:59:26.907" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15815" PostTypeId="2" ParentId="15786" CreationDate="2015-06-15T10:34:10.253" Score="2" Body="&lt;p&gt;As stated in other answers, the receivers used by FR24 is not the same receivers as ATS use. In a comment you indicate that this is irrelevant:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;I'm not asking about coverage, but position accuracy, which is&#xA;  independent of the receiver (either the receiver does or does not&#xA;  receive the airplane position).&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is however relevant indeed. Poor reception can lead to a poor update rate (only some of the broadcasts received), leading to old data being displayed. Also, you don't know what signal/data processing occurs between the receiver and you on FR24, and what processing would occur at the ATSU.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The performance specification for ADS-B is laid out in ICAO doc 9871 (which unfortunately comes with a bit of a price tag). Unfortunately, I don't have access to 9871, however, it is reflected in its various national ratifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following are quotes (my emphasis) from Annex 2, Part B in &lt;a href=&quot;http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32011R1207&quot; rel=&quot;nofollow&quot;&gt;EU 1207/2011&lt;/a&gt; (which most likely is quite harmonized with FAA/other regs, at least within the scope of this question):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§6 The primary data source providing the data items in point 3(h) and&#xA;  (i) shall be &lt;strong&gt;at least compatible with GNSS receivers&lt;/strong&gt; that perform&#xA;  receiver autonomous integrity monitoring (&lt;strong&gt;RAIM&lt;/strong&gt;) and fault detection&#xA;  and exclusion (&lt;strong&gt;FDE&lt;/strong&gt;), along with the output of corresponding&#xA;  measurement status information, as well as integrity containment bound&#xA;  and 95 % accuracy bound indications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§10. The total latency of the horizontal position data (the data items in point 3(h) and (i)) shall be equal to or less than &lt;strong&gt;1,5 second in 95&#xA;  % of all transmissions.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§11. The uncompensated latency of the horizontal position data (data item in point 3(h)) shall be equal to or less than &lt;strong&gt;0,6 second in 95 %&#xA;  of the cases and shall be equal to or less than 1,0 second in 99,9 %&#xA;  of all transmissions.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Point 3(h) and (i) are respectively: geodetic position and horizontal position quality indicators&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this, we can deduce that the accuracy of the position input will be bound to GNSS/RAIM, and that the latency of the position data will be in the order of a second, or less. (&lt;em&gt;This however says nothing between time to updates&lt;/em&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certification requirements of a GNSS-system is controlled by various regs, depending on the installation (ABAS/RAIM, SBAS, GBAS etc) and many of them once again have price tags, but just to get an idea of the precision an ADS-B system could expect we can look to former &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/E560CD9C6ACF8BA186256DC700717E0F?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;FAA TSO-129a&lt;/a&gt; (GPS/RAIM), in which it states that the equipment 2D position error must be contained to 0.124 nm for oceanic, en-route and terminal ops, at 95% confidence (about 230 meters).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual ADS-B equipment requirements are more involved than this (and the possible precision/accuracy of GNSS with a suitable augmentation system (SBAS/GBAS) is much higher), but these figures should at least give a ball park idea of its precision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be mentioned that the article you link to claims that primary radar is the primary surveillance method used by ATC. At least for most civilian ATC units, this is incorrect: Secondary surveillance radar (SSR) is the primary surveillance method, with primary radar sometimes being available as a supplement to SSR-data. As SSR is dependent on a transponder reply from the target aircraft, while a primary radar is able to detect objects without a transponder, ADS-B can not replace the supplementary function of a primary radar per se, but it can replace/extend the function of SSR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both FAA and Eurocontrol has stated ADS-B out will be required in certain airspace from 2020. In Australia it has been required above FL290 already since 2013.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastEditorUserId="7532" LastEditDate="2015-06-15T12:49:03.080" LastActivityDate="2015-06-15T12:49:03.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15816" PostTypeId="1" CreationDate="2015-06-15T10:56:46.270" Score="7" ViewCount="28108" Body="&lt;p&gt;I hear the term &quot;compressor stall&quot; when talking about turbine engine difficulties. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly does this mean? And how does a pilot diagnose and fix it - specifically, would there be any changes in the engine instruments compared to normal operation?&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2015-06-16T02:59:38.563" LastActivityDate="2015-11-20T08:12:35.623" Title="What exactly is a compressor stall?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15817" PostTypeId="2" ParentId="15813" CreationDate="2015-06-15T11:13:46.427" Score="9" Body="&lt;p&gt;For the &lt;em&gt;whole&lt;/em&gt; flight envelope, maybe not. Depends on the door design. Gear doors frequently have speed limits before they fly off on their own. Large openings create substantial drag, so we may find that the envelope is self-limiting: the aircraft can no longer reach speeds and/or altitudes where the opening is a big problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are too many variables for a simple answer.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-15T11:13:46.427" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15818" PostTypeId="1" CreationDate="2015-06-15T11:17:27.967" Score="5" ViewCount="837" Body="&lt;p&gt;As per the security rules, i think upto 100ml of liquid ( medicines, perfumes etc) can be taken on-board by a passenger but is it possible that, that 100ml can be converted to fumes/gas and contaminate the air inside the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any such incident has ever been reported?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-06-15T15:32:27.460" LastActivityDate="2018-08-13T15:50:24.980" Title="Is it possible to take a liquid/gas inside aircraft cabin to contaminate the air?" Tags="&lt;airliner&gt;&lt;security&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15819" PostTypeId="2" ParentId="15812" CreationDate="2015-06-15T11:24:58.210" Score="18" Body="&lt;p&gt;Qualifier: I am a master parachute rigger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bag serves two functions - it allows the suspension lines to straighten out in a controlled manner, and it prevents the canopy from inflating before the lines are fully stretched out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not always required - people who want a very fast opening can pack without a bag, I have done this many times myself. However, you do NOT want to do this after a drop of more than about 5 seconds. These jumpers open the main canopy immediately after exiting the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On main canopies the bag and pilot chute are connected to a ring on the top of the canopy. The assembly just follows behind. Some canopies have a mechanism to collapse the pilot chute and/or retract it onto the top of the canopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bag for the reserve canopy is not connected. This allows the reserve to still deploy if the pilot chute gets caught on something else, the bridle is extra long (longer than the suspension lines). It falls separately and usually lands within a kilometer of the airport, near the main canopy if that one was released when it malfunctioned. As they cost about $200 a set the jumpers will put considerable effort into finding it. We usually don't find it in high crops, and we usually don't try to find it at some places in Florida where there is an alligator ranch beside the airport.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-15T11:24:58.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15820" PostTypeId="2" ParentId="15818" CreationDate="2015-06-15T12:07:33.280" Score="12" Body="&lt;p&gt;To answer your first question: it depends what you mean by &quot;contaminate&quot;. The air in an aircraft cabin is constantly being renewed every two or three minutes (&lt;a href=&quot;http://www.airbus.com/aircraftfamilies/comfort/air-quality/&quot;&gt;source (Airbus)&lt;/a&gt; - Boeing aircraft are similar), and the airflow pattern is such that the air only flows &quot;across&quot; the cabin, not along it. In other words, any contaminant you introduce will only reach the passengers seated in the same row as you (and perhaps the rows directly behind and in front of you), and will only stay there for a few minutes before the air exchange carries it overboard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;About 50% of the air which leaves the cabin is recycled back into the cabin, but it passes through filters first, which will stop any particles but will let gases through. Statistically, the concentration of whatever was introduced will drop to nearly zero after two passes through the ventilation system (due to dilution with fresh outside air). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that the &quot;100ml&quot; rule is more designed to stop passengers from building liquid explosives aboard an aircraft (&lt;a href=&quot;http://blog.tsa.gov/2008/02/more-on-liquid-rules-why-we-do-things.html&quot;&gt;source (TSA)&lt;/a&gt;) than to stop them introducing harmful contaminants into the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know of any incidents where an airborne substance was used maliciously in an airplane cabin, but you would get a similar effect through an on-board fire. The aircraft's ventilation system is designed to clear the cabin and flight deck of smoke within a short period of time (often by disabling the air recirculation system and increasing the fresh air flow into the aircraft). &lt;/p&gt;&#xA;" OwnerUserId="1478" LastActivityDate="2015-06-15T12:07:33.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15821" PostTypeId="1" CreationDate="2015-06-15T12:40:44.137" Score="2" ViewCount="50" Body="&lt;p&gt;What happens when an aircraft is hit by lightning? (Assuming that none of the engines is hit). Is there some FAA regulation (or some other regulation) which makes it mandatory for aircraft manufacturers to ensure that minimum damage occurs to the aircraft when it's struck by lightning?&lt;/p&gt;&#xA;" OwnerDisplayName="user8882" LastEditorUserId="62" LastEditDate="2016-08-07T02:51:14.290" LastActivityDate="2016-08-07T02:51:14.290" Title="Aircraft in lightning" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;aircraft-limitations&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-06-15T12:53:18.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="15822" PostTypeId="1" CreationDate="2015-06-15T13:17:38.723" Score="2" ViewCount="96" Body="&lt;p&gt;I downloaded Delta flight schedules from &lt;a href=&quot;http://www.delta.com/content/dam/delta-www/pdfs/flight_schedules.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; but would like this information in a spreadsheet. Does something like that exist?&lt;/p&gt;&#xA;" OwnerUserId="4489" LastEditorUserId="1696" LastEditDate="2016-07-06T21:47:13.650" LastActivityDate="2016-07-06T21:47:13.650" Title="Where can I find Delta flight schedule information in a structured format?" Tags="&lt;flight-schedules&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-06-15T14:05:05.410" ContentLicense="CC BY-SA 3.0" />
  <row Id="15823" PostTypeId="1" AcceptedAnswerId="15825" CreationDate="2015-06-15T13:47:56.440" Score="23" ViewCount="17777" Body="&lt;p&gt;Flying exposes us to more radiation since we are closer to the sun, and there is less atmosphere to protect us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider an airline pilot flying on a routine and frequent basis. How much radiation is absorbed per flight hour, and per year?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="39" LastEditDate="2015-07-02T16:49:10.827" LastActivityDate="2015-07-02T16:49:10.827" Title="How much radiation is an airline pilot exposed to in a year?" Tags="&lt;airliner&gt;&lt;pilots&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15824" PostTypeId="2" ParentId="15813" CreationDate="2015-06-15T14:00:54.910" Score="27" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15396/open-door-on-small-plane/15397#15397&quot;&gt;Check out my answer here&lt;/a&gt; to a similar question (about what would happen if you open a door in flight). In short it depends largely on the plane but in the most general way of looking at it. You could do it up until you would need to pressurize the plane (or you would have wear O2 masks or something to be able to breathe). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_811&quot; rel=&quot;nofollow noreferrer&quot;&gt;UA Flight 811&lt;/a&gt; was able to make a safe decent and return to airport after its door blew out so large planes are maneuverable with out door. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/bdrlu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-3&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-3&lt;/a&gt; used in WWII for paratrooping regularly ran with their doors open. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/Uey6O.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you consider rear cargo ramps doors, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-130&lt;/a&gt; can open its rear ramp for &lt;a href=&quot;http://specialoperations.com/29014/worlds-first-combat-h-l-o-jump/&quot; rel=&quot;nofollow noreferrer&quot;&gt;HALO jumping&lt;/a&gt; at &lt;a href=&quot;https://en.wikipedia.org/wiki/High-altitude_military_parachuting&quot; rel=&quot;nofollow noreferrer&quot;&gt;high altitudes&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In typical HALO/HAHO insertions the troops jump from altitudes between 15,000 feet (4,600 m) and 35,000 feet (11,000 m)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uDXVJ.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is at least one other powered glider I can think of that can open its doors mid flight... &#xA;&lt;img src=&quot;https://i.stack.imgur.com/igc0R.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-06-16T18:34:11.827" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="15825" PostTypeId="2" ParentId="15823" CreationDate="2015-06-15T14:05:50.333" Score="33" Body="&lt;p&gt;The average additional annual dose for flight crew is 2.19 mSv (milli sieverts).  &lt;a href=&quot;http://www.hps.org/publicinformation/ate/faqs/commercialflights.html&quot;&gt;http://www.hps.org/publicinformation/ate/faqs/commercialflights.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical annual dose from background sources is 4 mSv (this varies enormously on the Earth's surface). However, as a rough order of thumb, the annual radiation dose of a flight crew member increases by about 50% compared to sitting on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison with other sources, having a chest CT scan provides you with a 7 mSv dose over the period of a few minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum permitted dose in one year for a radiation worker under US Federal Law is 50 mSv.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more comparisons of radiation dose, see &lt;a href=&quot;https://xkcd.com/radiation/&quot;&gt;https://xkcd.com/radiation/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a technical point, the premise of your question is incorrect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying exposes us to additional cosmic background radiation because we are at a greater height above the Earth's surface, not because we are closer to the sun. We are protected from cosmic radiation by the presence of the Earth's magnetic field, which extends far into space and is not an issue here except very close to the poles; and more importantly, by the layer of atmosphere above our heads that tends to absorb cosmic rays before they reach the surface. At 40,000 feet, the bulk of the atmosphere by mass is below you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not presently believed that a substantial fraction of these rays are emitted by the sun. For one, you will continue to be irradiated by them at night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(For interest, if you could see the cosmic background radiation, it would be approximately as bright on the night sky as star light is; for complex reasons the two energies are in rough equipartition.)&lt;/p&gt;&#xA;" OwnerUserId="8565" LastActivityDate="2015-06-15T14:05:50.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15826" PostTypeId="2" ParentId="14470" CreationDate="2015-06-15T14:16:39.733" Score="4" Body="&lt;p&gt;Niels Sundberg, the founder, owner and CEO of EZ (Sun Air of Scandinavia, a franchisee for British Airways) was also a captain for his airline with over 13,000 hours. He was forced to retire from flying paying passengers at 65 under EU regulations, which he describes as big blow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://delightmagazine.dk/niels-sundberg-the-sky-is-my-passion/&amp;amp;prev=search&quot; rel=&quot;nofollow&quot;&gt;http://delightmagazine.dk/niels-sundberg-the-sky-is-my-passion/&amp;amp;prev=search&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(In Danish)&lt;/p&gt;&#xA;" OwnerUserId="8565" LastActivityDate="2015-06-15T14:16:39.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15827" PostTypeId="2" ParentId="15791" CreationDate="2015-06-15T15:06:59.007" Score="4" Body="&lt;p&gt;There has been a televised test &lt;a href=&quot;https://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment&quot; rel=&quot;nofollow noreferrer&quot;&gt;crash of a Boeing 727&lt;/a&gt; that took place in Mexico.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane took off from General Rodolfo Sánchez Taboada International Airport in Mexicali, with the flight crew and a small group of passengers, as well as a number of crash dummies, and with a chase plane following close behind. As the flight progressed towards the Sonoran Desert of Baja California in Mexico, its occupants parachuted to safety. Slocum was the last one to leave the jet, four minutes before impact. Shanle then flew the jetliner by remote control, from the chase plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This started out fully manned, but ended with the pilot being the last to leave the craft, after handing control over to a remote operator in the chase plane.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There was a precursor to this flight: a crash of a &lt;a href=&quot;http://www.dfrc.nasa.gov/Gallery/Movie/CID/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 720&lt;/a&gt; (courtesy of &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;Peter Kampf&lt;/a&gt; from the comments), conducted by NASA in 1984. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this likely does not fall into the criteria of your question, since the documentation seems to indicate that the entire flight was remote controlled. Or at the very least does not explicitly state solo piloting.&lt;/p&gt;&#xA;" OwnerUserId="3860" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-06-15T21:03:53.530" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15828" PostTypeId="1" AcceptedAnswerId="15833" CreationDate="2015-06-15T15:32:55.777" Score="6" ViewCount="606" Body="&lt;p&gt;Given the fact that Helium is now readily available (as compared to times when Zeppelins were around), why isn't Lighter Than Air Aviation used for cheap travel?&lt;/p&gt;&#xA;" OwnerDisplayName="user8889" LastEditorUserId="8818" LastEditDate="2015-06-15T16:07:00.597" LastActivityDate="2015-06-15T16:51:48.677" Title="Lighter than Air Aircraft" Tags="&lt;economics&gt;&lt;efficiency&gt;&lt;zeppelin&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-06-15T17:26:32.430" ContentLicense="CC BY-SA 3.0" />
  <row Id="15829" PostTypeId="5" CreationDate="2015-06-15T15:36:35.410" Score="0" Body="&lt;p&gt;A Zeppelin is a powered lighter than air vehicle with a self-supporting hull and unpressurized gas bags. The word comes from the founder of the company which built most aircraft of this type, but is now used for all lighter-than-air vehicles with a rigid structure.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1961" LastEditDate="2015-06-15T15:52:04.460" LastActivityDate="2015-06-15T15:52:04.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15830" PostTypeId="4" CreationDate="2015-06-15T15:36:35.410" Score="0" Body="A Zeppelin is a type of rigid airship named after the German Count Ferdinand von Zeppelin who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's ideas were first formulated in 1874 and developed in detail in 1893. They were patented in Germany in 1895 and in the United States in 1899." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-15T16:52:43.613" LastActivityDate="2015-06-15T16:52:43.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15832" PostTypeId="2" ParentId="15813" CreationDate="2015-06-15T16:47:31.707" Score="43" Body="&lt;p&gt;Aloha Airlines &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot;&gt;Flight 243&lt;/a&gt; proved that it's possible for a plane to fly with about 25% of its roof missing. The door, however, appears to have remained closed until landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/1/1e/Aloha_Airlines_Flight_243_fuselage.png&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/1/1e/Aloha_Airlines_Flight_243_fuselage.png&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/1/1e/Aloha_Airlines_Flight_243_fuselage.png&quot;&gt;&lt;/a&gt;&lt;sup&gt;Image courtesy Wikipedia&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-06-15T16:47:31.707" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="15833" PostTypeId="2" ParentId="15828" CreationDate="2015-06-15T16:51:48.677" Score="6" Body="&lt;p&gt;There are many factors that have kept Lighter Than Air Aviation out of the mainstay, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Speed:&lt;/strong&gt; Airships are not exactly the most efficient means of moving through the air. As such &lt;a href=&quot;https://en.wikipedia.org/wiki/Airship#Comparison_with_heavier-than-air_aircraft&quot;&gt;their speed is far more limited&lt;/a&gt; than their heaver than air counterparts. For what its worth the main advantage of air travel in the modern world is speed. Its better to fly to Europe in 8 hours from New York than take a 3 week boat trip. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Size:&lt;/strong&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Rigid_airship&quot;&gt;Rigid&lt;/a&gt; or even &lt;a href=&quot;https://en.wikipedia.org/wiki/Semi-rigid_airship&quot;&gt;Semi Rigid&lt;/a&gt; airships are not small vehicles. They require very large hangars to keep them protected from the elements considering they are fabric covered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Capacity:&lt;/strong&gt; The largest airship ever made was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hindenburg-class_airship&quot;&gt;Hindenburg class&lt;/a&gt; of airships. Coming in twice as tall and 3 times longer than a modern 747 and in its biggest configuration only able to cary 73 passengers compared to 550 for the largest configuration of the smallest 747 built. Granted the Hindenburg was not laid out like a modern airliner (it was more like a cruise ship) considering the slow speeds it would need to be that way even today. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with Helium being easier to come buy, its just not efficient to fly such a large craft for so few people. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-15T16:51:48.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15834" PostTypeId="2" ParentId="15813" CreationDate="2015-06-15T16:55:28.490" Score="48" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Stratospheric_Observatory_for_Infrared_Astronomy&quot; rel=&quot;noreferrer&quot;&gt;Stratospheric Observatory for Infrared Astronomy (SOFIA)&lt;/a&gt; is a modified 747 that has an 5.5 m x 4.1 m door that is opened during flight for the installed in infrared telescope. But the door is usually closed during takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But according to this &lt;a href=&quot;http://spacenews.com/successful-landing-stuck-door-advances-sofia-testing/&quot; rel=&quot;noreferrer&quot;&gt;story&lt;/a&gt; there are emergency procedures to land with an open door and it had to do so once, when it became stuck half open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cXJDI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/LS5cV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;Images courtesy Wikipedia&lt;/p&gt;&#xA;" OwnerUserId="8891" LastEditorUserId="8891" LastEditDate="2015-06-16T06:26:46.550" LastActivityDate="2015-06-16T06:26:46.550" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15835" PostTypeId="1" CreationDate="2015-06-15T17:18:15.977" Score="10" ViewCount="2962" Body="&lt;p&gt;I was reading another question on this site when I saw this &lt;a href=&quot;https://aviation.stackexchange.com/a/2526/8818&quot;&gt;answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in the photo I copied below, this private jet has no cockpit door. On commercial aircraft the bullet-proof cockpit door is seen as the last line of defense against would-be hijackers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What security measures are in place to prevent unauthorized passenger access to the controls of private jets? Even though they are smaller and carry fewer people, a G650 or BBJ pointed in the wrong place can do a lot of damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Dassault-Falcon-50/0209264/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SVSOj.jpg&quot; alt=&quot;Private jet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8818" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2020-01-27T15:56:34.277" Title="What prevents a passenger from hijacking a private jet?" Tags="&lt;security&gt;&lt;regulations&gt;&lt;hijack&gt;&lt;private-jets&gt;" AnswerCount="8" CommentCount="10" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15836" PostTypeId="2" ParentId="15835" CreationDate="2015-06-15T17:24:52.130" Score="4" Body="&lt;p&gt;In your picture, the door is currently open.  It is most definitely there, but probably not re-enforced as commercial airline doors are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Very little physically prevents a passenger from entering the cockpit on a private charter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, with private planes, security is done on the ground.  The charter company does whatever diligence they feel is necessary to know their guests and their intentions before boarding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial airlines obviously cannot do extensive checks on all their passengers, but they do cross-check against lists like the No-Fly list.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-06-15T17:24:52.130" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15837" PostTypeId="2" ParentId="15818" CreationDate="2015-06-15T17:53:56.300" Score="5" Body="&lt;p&gt;&lt;strong&gt;Gases&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For it to be converted to a gas, it would have to either be stored in a pressurized container or be a liquid that happens to vaporize at room temperature in the relatively small pressure difference between the surface and the cabin pressure altitude. Pressurized gas containers are not allowed on board U.S. airline flights unless they are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Medical oxygen cylinders with in-tact and unmodified regulator valves,&lt;/li&gt;&#xA;&lt;li&gt;Part of a life vest, or&lt;/li&gt;&#xA;&lt;li&gt;Verifiably empty.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;From the TSA &lt;a href=&quot;http://www.tsa.gov/traveler-information/prohibited-items&quot; rel=&quot;nofollow noreferrer&quot;&gt;Prohibited Items List&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Allowed in checked or carry-on luggage:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Small compressed gas cartridges&#xA;  (Up to 2 in life vests and 2 spares. The spares must accompany the life vests and presented as one unit)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not allowed in any luggage:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fire extinguishers and other compressed gas cylinders&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the &quot;Can I bring my...?&quot; search blank on the &lt;a href=&quot;http://www.tsa.gov/traveler-information/prohibited-items&quot; rel=&quot;nofollow noreferrer&quot;&gt;same page&lt;/a&gt; with the search term &quot;compressed gas cylinder&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except for personal medical oxygen cylinders, you can only carry an EMPTY compressed gas cylinder on board a plane. To be permitted (in either carry-on or checked baggage), it must be clearly visible to the Transportation Security Officer (TSO) that the cylinder is empty. Personal oxygen is permitted if the regulatory valve has not been tampered with or removed.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aerosols&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerosols are allowed, but are subject to the same 3-1-1 rule as other liquids, that is, they must be in a 100 mL or less container which is then stored inside a 1 L / 1 qt. zip-top bag. As &lt;a href=&quot;https://aviation.stackexchange.com/a/15820/755&quot;&gt;Lightsider mentioned&lt;/a&gt;, these will almost certainly be filtered out of the air by the air filters in the ventilation system, as they are not in gaseous form (and likely are relatively large particles and/or molecules.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.tsa.gov/traveler-information/prohibited-items&quot; rel=&quot;nofollow noreferrer&quot;&gt;same TSA page&lt;/a&gt; using the search term &quot;aerosols,&quot; you get the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You may carry liquids, gels and aerosols in your carry-on bags only if they adhere to the 3-1-1 rule: containers must be 3.4 ounces or less; stored in a 1 quart/liter zip-top bag; 1 zip-top bag per person, placed in the screening bin. Larger amounts of non-medicinal liquids, gels, and aerosols must be placed in checked baggage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-06-15T17:53:56.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15838" PostTypeId="2" ParentId="15783" CreationDate="2015-06-15T18:42:12.297" Score="5" Body="&lt;p&gt;I think it's because the last 747-400 was built in 2009.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2009-title14-vol3/xml/CFR-2009-title14-vol3-sec121-162.xml&quot; rel=&quot;nofollow&quot;&gt;§121.162   ETOPS Type Design Approval Basis.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Except for a passenger-carrying airplane with more than two engines manufactured prior to February 17, 2015&lt;/strong&gt; and except for a two-engine&#xA;  airplane that, when used in ETOPS, is only used for ETOPS of 75&#xA;  minutes or less, no certificate holder may conduct ETOPS unless the&#xA;  airplane has been type design approved for ETOPS and each airplane&#xA;  used in ETOPS complies with its CMP document as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) For a two-engine airplane, that is of the same model&#xA;  airplane-engine combination that received FAA approval for ETOPS up to&#xA;  180 minutes prior to February 15, 2007, the CMP document for that&#xA;  model airplane-engine combination in effect on February 14, 2007.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) For a two-engine airplane, that is not of the same model&#xA;  airplane-engine combination that received FAA approval for ETOPS up to&#xA;  180 minutes before February 15, 2007, the CMP document for that new&#xA;  model airplane-engine combination issued in accordance with&#xA;  §25.3(b)(1) of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) For a two-engine airplane approved for ETOPS beyond 180 minutes,&#xA;  the CMP document for that model airplane-engine combination issued in&#xA;  accordance with §25.3(b)(2) of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) &lt;strong&gt;For an airplane with more than 2 engines manufactured on or&#xA;  after February 17, 2015&lt;/strong&gt;, the CMP document for that model&#xA;  airplane-engine combination issued in accordance with §25.3(c) of this&#xA;  chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;§25.3   Special provisions for ETOPS type design approvals.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Applicability. This section applies to an applicant for ETOPS type&#xA;  design approval of an airplane:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) That has an existing type certificate on February 15, 2007; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For which an application for an original type certificate was&#xA;  submitted before February 15, 2007.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Airplanes with two engines. (1) For ETOPS type design approval of&#xA;  an airplane up to and including 180 minutes, an applicant must comply&#xA;  with §25.1535, except that it need not comply with the following&#xA;  provisions of Appendix K, K25.1.4, of this part:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) K25.1.4(a), fuel system pressure and flow requirements;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) K25.1.4(a)(3), low fuel alerting; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) K25.1.4(c), engine oil tank design.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For ETOPS type design approval of an airplane beyond 180 minutes&#xA;  an applicant must comply with §25.1535.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) &lt;strong&gt;Airplanes with more than two engines. An applicant for ETOPS&#xA;  type design approval must comply with §25.1535 for an airplane&#xA;  manufactured on or after February 17, 2015, except that, for an&#xA;  airplane configured for a three person flight crew, the applicant need&#xA;  not comply with Appendix K, K25.1.4(a)(3), of this part, low fuel&#xA;  alerting.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-06-15T19:35:14.543" LastActivityDate="2015-06-15T19:35:14.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15839" PostTypeId="2" ParentId="15728" CreationDate="2015-06-15T18:46:31.870" Score="9" Body="&lt;p&gt;I see no mention of &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2009-title14-vol3/xml/CFR-2009-title14-vol3-sec121-161.xml&quot;&gt;14CFR 121.161&lt;/a&gt; so here it is.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§ 121.161 Airplane limitations: Type of route.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraph (e) of this section, unless&#xA;  approved by the Administrator in accordance with Appendix P of this&#xA;  part and authorized in the certificate holder's operations&#xA;  specifications, no certificate holder may operate a&#xA;  turbine-engine-powered airplane over a route that contains a point—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Farther than a flying time from an Adequate Airport (at a&#xA;  one-engine-inoperative cruise speed under standard conditions in still&#xA;  air) of 60 minutes for a two-engine airplane or 180 minutes for a&#xA;  passenger-carrying airplane with more than two engines;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Within the North Polar Area; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Within the South Polar Area.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Except as provided in paragraph (c) of this section, no&#xA;  certificate holder may operate a land airplane (other than a DC-3,&#xA;  C-46, CV-240, CV-340, CV-440, CV-580, CV-600, CV-640, or Martin 404)&#xA;  in an extended overwater operation unless it is certificated or&#xA;  approved as adequate for ditching under the ditching provisions ofpart&#xA;  25 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Until December 20, 2010, a certificate holder may operate, in an&#xA;  extended overwater operation, a nontransport category land airplane&#xA;  type certificated after December 31, 1964, that was not certificated&#xA;  or approved as adequate for ditching under the ditching provisions&#xA;  ofpart 25 of this chapter.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) Unless authorized by the Administrator based on the character of&#xA;  the terrain, the kind of operation, or the performance of the airplane&#xA;  to be used, no certificate holder may operate a&#xA;  reciprocating-engine-powered airplane over a route that contains a&#xA;  point farther than 60 minutes flying time (at a one-engine-inoperative&#xA;  cruise speed under standard conditions in still air) from an Adequate&#xA;  Airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Operators of turbine-engine powered airplanes with more than two&#xA;  engines do not need to meet the requirements of paragraph (a)(1) of&#xA;  this section until February 15, 2008.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[Doc. No. 7329, 31 FR 13078, Oct. 8, 1966 as amended by Amdt. 121-162,&#xA;  45 FR 46739, July 10, 1980; Amdt. 121-251, 60 FR 65927, Dec. 20, 1995;&#xA;  Amdt. 121-329, 72 FR 1879, Jan. 16, 2007]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="1696" LastEditDate="2015-06-15T19:33:19.553" LastActivityDate="2015-06-15T19:33:19.553" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15840" PostTypeId="1" CreationDate="2015-06-15T20:08:39.807" Score="3" ViewCount="203" Body="&lt;p&gt;I desperately need a map of an airport aerodrome like the ones used for tracking the movements of aircraft similar to the picture below and I don't know where I can find these ones :&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9caES.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="8056" LastEditorUserId="19" LastEditDate="2015-06-15T20:17:06.640" LastActivityDate="2015-06-15T20:31:23.743" Title="Where can I find numeric maps of aerodromes?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15841" PostTypeId="2" ParentId="15840" CreationDate="2015-06-15T20:15:10.233" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.openstreetmap.org/export#map=14/32.8997/-97.0256&quot; rel=&quot;nofollow&quot;&gt;OpenStreetMap&lt;/a&gt; is a good place to start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've used it for a project with real aircraft data and found that the OSM map of the airport I was interested in had a small offset. Using &lt;a href=&quot;http://wiki.openstreetmap.org/wiki/JOSM&quot; rel=&quot;nofollow&quot;&gt;JOSM&lt;/a&gt; I was able to correct for the offset and add missing taxiways and additional features. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also tried to use PDF based airport diagrams from various Aeronautical Information Publications (AIP) but I was not successful in extracting the specific elements I was interested in. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-15T20:15:10.233" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15842" PostTypeId="2" ParentId="15840" CreationDate="2015-06-15T20:31:23.743" Score="4" Body="&lt;p&gt;Airport Diagrams such as this one of &lt;a href=&quot;https://en.wikipedia.org/wiki/Northeast_Philadelphia_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;KPNE&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ijdKe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;are published &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/diagrams/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here on the FAA website&lt;/a&gt; as well as in &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;in the airport facilities directory&lt;/a&gt;. These are up to date and considered legal for navigation as far as I know. If you are looking for them in another type of format that may be tough, you can try reaching out to the specific airports or the FAA directly. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-15T20:31:23.743" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15843" PostTypeId="1" CreationDate="2015-06-15T21:20:51.097" Score="4" ViewCount="953" Body="&lt;p&gt;Would it be possible or practical for the US Air Force to replace the Thunderbird pilots with drones?  The drones could perform more difficult maneuvers and do them more precisely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The University of Pennsylvania is successfully working on small-scale formation flying.  &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/YQIMGV5vtd4?start=45&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2cBHl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2141" LastEditorUserId="2141" LastEditDate="2015-06-16T00:03:30.273" LastActivityDate="2018-10-14T23:47:18.503" Title="Could the US Air Force ever replace the Thunderbird pilots with drones?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;airshow&gt;&lt;us-air-force&gt;" AnswerCount="3" CommentCount="21" FavoriteCount="1" ClosedDate="2018-10-12T19:31:34.323" ContentLicense="CC BY-SA 3.0" />
  <row Id="15844" PostTypeId="2" ParentId="15813" CreationDate="2015-06-15T21:41:14.200" Score="17" Body="&lt;p&gt;Since comments mentioned that not all of the outcomes from &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;noreferrer&quot;&gt;Aloha 243&lt;/a&gt; were exactly safe, here's another example that actually was quite safe:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://media3.s-nbcnews.com/j/MSNBC/Components/Photo/_new/110405-southwest-hmed.grid-6x2.jpg&quot; alt=&quot;Southwest 812&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_812&quot; rel=&quot;noreferrer&quot;&gt;Southwest 812&lt;/a&gt; had a large hole open in the roof during flight at cruise altitude, resulting in rapid depressurization at 34,000 ft. 2 of the 123 people on board (a flight attendant and a passenger) suffered minor injuries. The plane diverted to Yuma, Arizona and landed safely about 26 minutes after the depressurization. As with the other cases, the doors were technically shut, but I'm not so sure that that made much difference.&lt;/p&gt;&#xA;&lt;p&gt;Furthermore, this was &lt;em&gt;not the first time this had happened.&lt;/em&gt; Less than 2 years before this incident, &lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_2294&quot; rel=&quot;noreferrer&quot;&gt;Southwest 2294&lt;/a&gt; had a similar incident (though with a smaller hole) and safely diverted to Charleston, WV with &lt;em&gt;no injuries at all.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;What's more: according to the &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N387SW&quot; rel=&quot;noreferrer&quot;&gt;FAA's registry&lt;/a&gt; and &lt;a href=&quot;http://www.airfleets.net/ficheapp/plane-b737-26602.htm&quot; rel=&quot;noreferrer&quot;&gt;airfleets.net&lt;/a&gt;, it looks like both of these aircraft were returned to service and are still actively flying for Southwest! So, it looks like both the &amp;quot;you can walk away from it&amp;quot; requirement and the &amp;quot;the aircraft is reusable&amp;quot; preference were met in both instances.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;The Boeing 727&lt;/h2&gt;&#xA;&lt;p&gt;Another case that actually doesn't involve any structural damage at all is the 727 and its airstair. In the famous case of &lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper#Back_in_the_air&quot; rel=&quot;noreferrer&quot;&gt;D.B. Cooper's hijacking&lt;/a&gt;, this occurred while the aircraft was pressurized. According to the wiki on the incident, the result was the following:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The crew soon noticed a subjective change of air pressure, indicating that the aft door was open.&lt;/p&gt;&#xA;&lt;p&gt;At approximately 8:13 pm the aircraft's tail section sustained a sudden upward movement, significant enough to require trimming to bring the plane back to level flight.[33] At approximately 10:15 pm Scott and Rataczak landed the 727, with the aft airstair still deployed, at Reno Airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Additionally, some skydiving clubs even offered dives from the 727 for many years, though these presumably didn't pressurize the cabin. I'm not sure whether this is still offered.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-17T18:02:37.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15845" PostTypeId="2" ParentId="11956" CreationDate="2015-06-15T23:05:16.097" Score="0" Body="&lt;p&gt;Maybe this helps, although from 2013&#xA;&quot;Superjet&quot; variable cycle jet engine could power future fighter aircraft &#xA;&lt;a href=&quot;http://www.gizmag.com/ge-aviation-develop-advent-variable-cycle-jet-engine/25556/&quot; rel=&quot;nofollow&quot;&gt;http://www.gizmag.com/ge-aviation-develop-advent-variable-cycle-jet-engine/25556/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8664" LastActivityDate="2015-06-15T23:05:16.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15846" PostTypeId="2" ParentId="15835" CreationDate="2015-06-16T00:32:41.197" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What security measures are in place to prevent unauthorized passenger access to the controls of private jets?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;None. The passengers outnumber the pilots, and unlike commercial jets are not outnumbered by passengers who prefer the original scheduled route to the new one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also be very easy to arrange pickup at a quiet airstrip, kill the crew, stuff the bodies in a car trunk and do the whole flight without them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason this isn't much of a concern is because small jets have neither the mass nor fuel capacity to do anywhere near the amount of damage possible with an airliner. As an example, when I was in college a light aircraft hit a building on approach to the airport, and &lt;em&gt;nobody noticed&lt;/em&gt;. The building was the city hospital, the plane struck an empty floor and sat there with the tail sticking out. ATC wondered where it went, asked the next inbound to have a look, and then phoned the building. Staff went to the appropriate room and extracted the injured (but not dead) pilot and passengers. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-16T00:32:41.197" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="15847" PostTypeId="1" AcceptedAnswerId="15848" CreationDate="2015-06-16T00:44:24.253" Score="25" ViewCount="6666" Body="&lt;p&gt;The call sign of U.S. Airways is &quot;Cactus&quot;, and that of British Airways is &quot;Speedbird&quot;; while for Malaysia Airlines is &quot;Malaysia&quot;, Qantas is just simple &quot;Qantas&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it that the call signs of some airlines are so different from their names?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-07-06T18:05:16.057" LastActivityDate="2018-08-22T09:21:48.953" Title="Why are the call signs of some airlines completely different than their name?" Tags="&lt;commercial-aviation&gt;&lt;radio-communications&gt;&lt;commercial-operations&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15848" PostTypeId="2" ParentId="15847" CreationDate="2015-06-16T01:21:03.273" Score="28" Body="&lt;p&gt;I found this on &lt;a href=&quot;https://en.wikipedia.org/wiki/Airline_codes&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some call signs are less obviously associated with a particular airline than others. This might be for historic reasons (South African Airways uses the callsign &quot;Springbok&quot;, hearkening back to the airline's old livery which featured a springbok), or possibly to avoid confusion with a call sign used by an established airline. Companies' assigned names may change as a result of mergers, acquisitions, or change in company name or status; British Airways uses BOAC's old callsign (&quot;Speedbird&quot;), as British Airways was formed by a merger of BOAC and British European Airways. Country names can also change over time and new call signs may be agreed in substitution for traditional ones.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Before America West bought US Airways, their callsigns were Cactus (associated with the deserts of the American West) and USAir. After the merger, the combined airline kept the better-known (airline) name, and the other airline's callsign. Now, after the acquisition/merger of American Airlines, they're using that airline's name &lt;em&gt;and&lt;/em&gt; callsign.  Leading to more than a few radio calls recently (late spring / early summer 2015) along the lines of&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Center, Cactuuu...merican 123, FL 350&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="2556" LastEditDate="2018-08-22T09:21:48.953" LastActivityDate="2018-08-22T09:21:48.953" CommentCount="4" CommunityOwnedDate="2015-06-16T01:21:03.273" ContentLicense="CC BY-SA 4.0" />
  <row Id="15849" PostTypeId="1" AcceptedAnswerId="15850" CreationDate="2015-06-16T01:21:52.727" Score="8" ViewCount="2719" Body="&lt;p&gt;I read this while I was preparing for my knowledge test:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The heading indicator is not direction-seeking. It is important to&#xA;  check its indication frequently and reset it with reference to the&#xA;  magnetic compass.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and I am doing this all the time during flight time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why don't small aircraft manufacturer make the Heading Indicator magnetic instead of gyro? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="3455" LastEditDate="2015-06-16T01:27:32.333" LastActivityDate="2015-06-16T20:23:51.083" Title="Why Heading Indicator is not magnetic itself and need magnetic compass?" Tags="&lt;flight-instruments&gt;&lt;heading&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15850" PostTypeId="2" ParentId="15849" CreationDate="2015-06-16T01:52:09.707" Score="15" Body="&lt;p&gt;Compass readings &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_compass_turns&quot; rel=&quot;noreferrer&quot;&gt;during turns are inaccurate&lt;/a&gt; and sometimes display turns &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/comp.htm&quot; rel=&quot;noreferrer&quot;&gt;when you are heading straight but accelerating&lt;/a&gt;. As such you need something that is referenced to the airframe turning itself. This is where the gyro comes in handy. Since it's referenced to the airframe and relatively unaffected over short periods of time it gives you your heading when your compass can not. You can also &quot;time your turns&quot; using the turn coordinator and a stop watch should your heading indicator fail. It should be noted that a timed turn will only work if the turn remains coordinated (no slip or skid) further more most turn coordinators are set up for 2 minute turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://missions.capnhq.gov/ops/DOT/school/L23CockpitFam/magneticcompass.cfm&quot; rel=&quot;noreferrer&quot;&gt;errors&lt;/a&gt; are as follows    &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;If on a northerly heading and a turn is made toward east or west, the initial indication of the compass lags or indicates a turn in the&#xA;  opposite direction. The lag diminishes as the turn progresses toward&#xA;  the east or west where there is no turning error.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;If on a southerly heading and a turn is made toward east or west, the initial indication of the compass needle will indicate a greater&#xA;  amount of turn than is actually made. This lead also diminishes as the&#xA;  turn progresses toward east or west where there is no turn error.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;If a turn is made to a northerly heading from any direction, the compass indication when approaching northerly heading leads or is&#xA;  ahead of the turn. Therefore, the roll out of the turn is made before&#xA;  the desired heading is reached. If a turn is made to a southerly&#xA;  heading from any direction, the compass indication when approaching&#xA;  southerly headings lags behind the turn. Therefore, the roll out is&#xA;  made after the desired heading is passed. The amount of lead or lag is&#xA;  maximum on north / south headings and depends upon the angle of bank&#xA;  used and the latitude of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;When on an east or west heading, no error is apparent while entering a turn to north or south. However, an increase in airspeed&#xA;  will cause the compass to indicate a turn toward north. A decrease in&#xA;  airspeed will cause the compass to indicate a turn toward south.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The constant need to reset it is related to &lt;a href=&quot;https://en.wikipedia.org/wiki/Precession&quot; rel=&quot;noreferrer&quot;&gt;gyroscopic precession&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-16T20:23:51.083" LastActivityDate="2015-06-16T20:23:51.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15851" PostTypeId="2" ParentId="15807" CreationDate="2015-06-16T02:15:27.170" Score="15" Body="&lt;p&gt;In short: No, there is absolutely no feasible way of integrating midair rearming with our current equipment.  This would require a retooling of every pylon in existence to fix a problem that, frankly, doesn't exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual long answer is far outside the scope of this question and involves explaining the intricacies of the pylons to include thing like arming wires, sway braces, and a whole litany of other insurmountable problems that current technology cannot address.  And that's if you could even find a reliable method to transfer a 500 pound piece of concrete from one aircraft to another.  Hit any turbulence and that bomb becomes an inert wrecking ball that is sure to do damage in the 100,000's.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-06-16T02:23:42.507" LastActivityDate="2015-06-16T02:23:42.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15852" PostTypeId="2" ParentId="15847" CreationDate="2015-06-16T02:56:35.650" Score="19" Body="&lt;p&gt;More reasons call signs might not be the name of the airline would include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You need to have a call sign that contains few syllables rather than many, and that comes across relatively distinctly when communications are bad. The radio traffic can be fast, furious, and filled with static.&lt;/li&gt;&#xA;&lt;li&gt;You need to have a call sign that doesn't expose you to ridicule. For example, when UPS first started flying with their own aircraft (as opposed to using contract aircraft and crews, which they first did), they used the call sign &quot;brown tail.&quot; That didn't last long.&lt;/li&gt;&#xA;&lt;li&gt;You need to have a call sign that does not give you political problems. For example, I worked for an airline that was known to be owned by Jewish interests and whose major route was New York to Tel Aviv. We also did a lot of charters. There was no way we could get overfly permits from either Iran or Saudi Arabia using our usual call sign, so we had an alternate, little used call sign for those flights.&lt;/li&gt;&#xA;&lt;li&gt;You may be operating a contract flight. I flew many such flights, and the call signs I can offhand remember using included: Speedbird, Air India, Garuda, United, Japan Air, and Delta. Also on military charters we often used a military call sign, but I can't remember what it was. It was set up especially for the military airlift for Operation Desert Shield, the buildup for the first Gulf war.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-06-16T08:01:11.993" LastActivityDate="2015-06-16T08:01:11.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15853" PostTypeId="1" CreationDate="2015-06-16T03:44:40.093" Score="11" ViewCount="3329" Body="&lt;p&gt;It is a well known fact that some planes like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-2#Design_and_development&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-2&lt;/a&gt; can fly backwards since their stall speed is lower than the speed of the winds they can stably fly into. My question is what is the fastest recorded backward flying plane and is there video of this phenomenon?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In response to the comments by @Simon et al the term &lt;strong&gt;backwards&lt;/strong&gt; was vague - &lt;strong&gt;backwards relative to the ground&lt;/strong&gt; would have been more accurate. &lt;/p&gt;&#xA;" OwnerUserId="8896" LastEditorUserId="8896" LastEditDate="2015-09-01T20:19:51.820" LastActivityDate="2019-07-05T14:34:18.057" Title="What is the fastest recorded backward flying plane?" Tags="&lt;stall&gt;&lt;airspeed&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="15854" PostTypeId="2" ParentId="406" CreationDate="2015-06-16T04:19:32.807" Score="1" Body="&lt;p&gt;Canadian Class F is better compared to U.S. Special Use Airspace, if you read the regs for it, it covers the Canadian equivalent of Warning, Alert, Restricted, Prohibited, Military Operation, and Controlled Firing Areas. Interesting that in the U.S. we do not depict,or inform about controlled firing areas, Spotter aircraft, and controllers, prevent non-participant aircraft from being harmed. But they are depicted on Canadian charts, and basically treated like prohibited, or restricted areas as needed.&lt;/p&gt;&#xA;" OwnerUserId="8897" LastActivityDate="2015-06-16T04:19:32.807" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15855" PostTypeId="1" CreationDate="2015-06-16T04:59:03.583" Score="5" ViewCount="300" Body="&lt;p&gt;Is it mandatory have separate certification for aircraft operating CAT III Operations on airports having elevation more than 2500 feet? If so do that aircraft are to carry any additional equipment?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of our airline operator has submitted a list of their aircraft which are certified for CAT III operations at airports above 2500 feet elevation. We are yet to be equipped with CAT III, hence we would like to know if we have to have any additional ground systems to enable all aircraft to operate CAT III.&lt;/p&gt;&#xA;" OwnerUserId="8866" LastEditorUserId="14897" LastEditDate="2018-01-14T18:34:38.907" LastActivityDate="2019-02-15T11:45:16.860" Title="Are aircraft separately certified for CAT III ops for +2500 feet elevation?" Tags="&lt;aircraft-certification&gt;&lt;autoland&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15856" PostTypeId="2" ParentId="15816" CreationDate="2015-06-16T05:14:52.513" Score="6" Body="&lt;p&gt;A compressor stall occurs when there is a disruption or breakdown of airflow through a turbine engine.  It can usually be identified by a loud bang, pop, or buzzing sound.  Expect to feel a loss of thrust, see your RPM winding back, and your EGT/ITT/FTIT either increase or decrease based on your altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything that causes a disruption of airflow can cause a compressor stall.  Some of the more popular things are engine outside or near the edge of its envelope, bird strikes or ingestion, hot exhaust from a preceding jet, certain maneuvering, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most engines you can clear the stall and/or catch it in idle by retarding the throttle.  An additional step in the T-38 is to push the ENGINE START button.  The F-16 has a few more steps based on if the stalls are happening during AB or non-AB operation.  In general though, retard the throttle to either MIL or IDLE and see if this stops the stalls; if not, shut the engine down and perform an airstart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of a compressor stall with any aircraft it's going to be land as soon as possible.&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-16T05:14:52.513" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15857" PostTypeId="5" CreationDate="2015-06-16T05:41:34.640" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-16T05:41:34.640" LastActivityDate="2015-06-16T05:41:34.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15858" PostTypeId="4" CreationDate="2015-06-16T05:41:34.640" Score="0" Body="The United States Air Force (USAF) is the aerial warfare service branch of the United States Armed Forces and one of the seven American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on 18 September 1947 under the National Security Act of 1947." OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-09-18T23:46:39.060" LastActivityDate="2019-09-18T23:46:39.060" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15859" PostTypeId="5" CreationDate="2015-06-16T05:43:21.313" Score="0" Body="&lt;p&gt;Occasionally, however, the hijackers have flown the aircraft themselves, such as the September 11 attacks of 2001. In at least three cases, the plane was hijacked by the official pilot or co-pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike the typical hijackings of land vehicles or ships, skyjacking is not usually committed for robbery or theft. Most aircraft hijackers intend to use the passengers as hostages, either for monetary ransom or for some political or administrative concession by authorities. Motives vary from demanding the release of certain inmates (notably IC-814), highlighting the grievances of a particular community (notably AF 8969) to political asylum (notably ET 961). Hijackers also have used aircraft as a weapon to target particular locations (notably during the September 11, 2001 attacks).&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:52:06.530" LastActivityDate="2015-06-16T12:52:06.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15860" PostTypeId="4" CreationDate="2015-06-16T05:43:21.313" Score="0" Body="Aircraft hijacking (also known as aircraft piracy, especially within the special aircraft jurisdiction of the United States, and informally as skyjacking) is the unlawful seizure of an aircraft by an individual or a group. In most cases, the pilot is forced to fly according to the orders of the hijackers. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:43:18.127" LastActivityDate="2015-06-16T12:43:18.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15861" PostTypeId="5" CreationDate="2015-06-16T05:45:48.017" Score="0" Body="&lt;p&gt;Almost all production business jets, such as General Dynamics' Gulfstream and the Gates Lear Jet (now built by Bombardier), have had two or three engines, though the Jetstar, an early business jet, had four. Advances in engine reliability and power have rendered four-engine designs obsolete, and only Dassault Aviation still builds three-engine models (in the Falcon line). The emerging market for so-called &quot;very light jets&quot; and &quot;personal jets&quot;, has seen the introduction (at least on paper) of several single-engine designs as well.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:55:42.457" LastActivityDate="2015-06-16T12:55:42.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15862" PostTypeId="4" CreationDate="2015-06-16T05:45:48.017" Score="0" Body="A business jet, private jet, or bizjet, or simply B.J., is a jet aircraft designed for transporting small groups of people. Business jets may be adapted for other roles, such as the evacuation of casualties or express parcel deliveries, and some are used by public bodies, government officials or the armed forces. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:53:42.363" LastActivityDate="2015-06-16T12:53:42.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15863" PostTypeId="5" CreationDate="2015-06-16T05:48:06.170" Score="0" Body="&lt;p&gt;&lt;strong&gt;Axial compressor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Axial compressors are used in medium to large thrust Gas turbine engines, because the alternative centrifugal units would be too heavy and too large in cross-sectional area. At smaller sizes, the axial blading at the rear of the compressor loses its robustness and is difficult to manufacture accurately. Consequently, manufacturers tend replace the rear stages with a centrifugal unit. The compression system is then said to be axial-centrifugal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Centrifugal compressor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls Royce Goblin II numbered cutaway. The impeller of the centrifugal compressor is number 12&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At even smaller sizes, particularly in turboprop/turboshaft applications, the compression system is either a single centrifugal or has two centrifugal units connected in series (i.e. double-centrifugal).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mixed flow compressor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the future, mixed flow compressors may feature at the small end of the market, particularly in turbofans, where the relatively large diameter across the diffuser of a centrifugal compressor is a significant disadvantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Staged compression&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Two stage&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high overall pressure ratios, the compression system is usually split into two units; a Low Pressure (LP) Compressor mounted on one shaft followed by an High Pressure (HP) Compressor mounted on the HP shaft and driven by its own (HP) turbine. On civil turbofans, the first stage of the LP Compressor is often a single stage fan. If the HP Compressor pressure ratio exceeds about 4.5:1, then the unit will probably have variable geometry (i.e. variable stators) on the first few stages, to make the surge line on the compressor map more shallow, to accommodate the shallow working line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Three stage&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On their large civil turbofans, Rolls-Royce split the compression system into three: a Fan, an Intermediate Pressure (IP) Compressor and an HP Compressor, each unit being driven by its own turbine unit. The RB199 military turbofan also has this arrangement.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:51:20.623" LastActivityDate="2015-06-16T12:51:20.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15864" PostTypeId="4" CreationDate="2015-06-16T05:48:06.170" Score="0" Body="As the name suggests, gas turbine engine compressors provide the compression part of the gas turbine engine thermodynamic cycle. There are three basic categories of gas turbine engine compressor: axial compressor, centrifugal compressor, and mixed-flow compressor. A fourth, unusual, type is the free-piston gas generator, which combines the functions of compressor and combustion chamber in one unit." OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-02-03T14:06:10.857" LastActivityDate="2019-02-03T14:06:10.857" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15865" PostTypeId="5" CreationDate="2015-06-16T05:48:36.543" Score="0" Body="&lt;p&gt;Changing the setting of a trim tab adjusts the neutral or resting position of a control surface (such as an elevator or rudder). As the desired position of a control surface changes (corresponding mainly to different speeds), an adjustable trim tab will allow the operator to reduce the manual force required to maintain that position—to zero, if used correctly. Thus the trim tab acts as a servo tab. Because the center of pressure of the trim tab is farther away from the axis of rotation of the control surface than the center of pressure of the control surface, the moment generated by the tab can match the moment generated by the control surface. The position of the control surface on its axis will change until the torques from the control surface and the trim surface balance each other.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:55:37.240" LastActivityDate="2015-06-16T12:55:37.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15866" PostTypeId="4" CreationDate="2015-06-16T05:48:36.543" Score="0" Body="Trim tabs are small surfaces connected to the trailing edge of a larger control surface on aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface." OwnerUserId="8547" LastEditorUserId="511" LastEditDate="2015-06-16T06:04:28.487" LastActivityDate="2015-06-16T06:04:28.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15867" PostTypeId="5" CreationDate="2015-06-16T05:50:27.653" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-16T05:50:27.653" LastActivityDate="2015-06-16T05:50:27.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15868" PostTypeId="4" CreationDate="2015-06-16T05:50:27.653" Score="0" Body="Aircraft subsystem is a sub domain of the whole aircraft. Any system of the aircraft which helps the aircraft to be airborne (and fly safely) is called an Aircraft subsystem." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:43:11.793" LastActivityDate="2015-06-16T12:43:11.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15869" PostTypeId="5" CreationDate="2015-06-16T05:51:06.883" Score="0" Body="&lt;p&gt;Vibration is occasionally &quot;desirable&quot;. For example, the motion of a tuning fork, the reed in a woodwind instrument or harmonica, or mobile phones or the cone of a loudspeaker is desirable vibration, necessary for the correct functioning of the various devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More often, vibration is undesirable, wasting energy and creating unwanted sound – noise. For example, the vibrational motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations can be caused by imbalances in the rotating parts, uneven friction, the meshing of gear teeth, etc. Careful designs usually minimize unwanted vibrations.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:42:53.010" LastActivityDate="2015-06-16T12:42:53.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15870" PostTypeId="4" CreationDate="2015-06-16T05:51:06.883" Score="0" Body="Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:43:46.520" LastActivityDate="2015-06-16T12:43:46.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15871" PostTypeId="5" CreationDate="2015-06-16T05:51:45.897" Score="0" Body="&lt;p&gt;The housing is integral with the tail skin and, like the conventional tail rotor it replaces, is intended to counteract the torque of the main rotor. It was first developed by the French company Sud Aviation (now part of Airbus Helicopters) and is installed on many of their helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While conventional tail rotors typically have two or four blades, Fenestrons have between eight and 18 blades. These may have variable angular spacing, so that the noise is distributed over different frequencies. The housing allows a higher rotational speed than a conventional rotor, allowing it to have smaller blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term Fenestron is a trademark of Eurocopter. It comes from the modern French for a small window, and is ultimately from the Latin fenestra for window.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:51:26.060" LastActivityDate="2015-06-16T12:51:26.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15872" PostTypeId="4" CreationDate="2015-06-16T05:51:45.897" Score="0" Body="A Fenestron (or fantail, sometimes called &quot;fan-in-fin&quot;) is a protected tail rotor of a helicopter operating like a ducted fan. Placing the fan within a duct reduces tip vortex losses, shields the tail rotor from damage, is much quieter than a conventional tail rotor, and shields ground crews from the hazard of a spinning rotor." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:41:32.843" LastActivityDate="2015-06-16T12:41:32.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15873" PostTypeId="5" CreationDate="2015-06-16T05:53:04.863" Score="0" Body="&lt;p&gt;Any queries regarding flashback in the airplane engines should be tagged along with this tag.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:51:33.380" LastActivityDate="2015-06-16T12:51:33.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15874" PostTypeId="4" CreationDate="2015-06-16T05:53:04.863" Score="0" Body="Flashback is the travel of the flame from an Internal Combustion Chamber to the fuel tank through the tube (pipe) which brings the fuel to the chamber for combustion." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:35:16.797" LastActivityDate="2015-06-16T12:35:16.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15875" PostTypeId="5" CreationDate="2015-06-16T05:53:45.513" Score="0" Body="&lt;p&gt;Source control, filtration and the use of ventilation to dilute contaminants are the primary methods for improving indoor air quality in most buildings. Residential units can further improve indoor air quality by routine cleaning of carpets and area rugs. EPA has guidelines for frequency of cleaning based on traffic, number of household members, pets, children and smokers. Carpets and rugs act like an air filter and must be cleaned.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:42:31.937" LastActivityDate="2015-06-16T12:42:31.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15876" PostTypeId="4" CreationDate="2015-06-16T05:53:45.513" Score="0" Body="Indoor air quality (IAQ) is a term which refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. IAQ can be affected by gases (including carbon monoxide, radon, volatile organic compounds), particulates, microbial contaminants (mold, bacteria), or any mass or energy stressor that can induce adverse health conditions." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:53:34.143" LastActivityDate="2015-06-16T12:53:34.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15877" PostTypeId="5" CreationDate="2015-06-16T05:55:04.713" Score="0" Body="&lt;p&gt;The controls (stick and rudder) for rotary wing aircraft (helicopter or autogyro) accomplish the same motions about the three axes of rotation, but manipulate the rotating flight controls (main rotor disk and tail rotor disk) in a completely different manner.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="511" LastEditDate="2015-06-16T06:03:02.157" LastActivityDate="2015-06-16T06:03:02.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15878" PostTypeId="4" CreationDate="2015-06-16T05:55:04.713" Score="0" Body="Use for control surfaces; for the cockpit controls, use [flight-controls] instead." OwnerUserId="8547" LastEditorUserId="14897" LastEditDate="2021-04-28T03:59:00.237" LastActivityDate="2021-04-28T03:59:00.237" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15879" PostTypeId="5" CreationDate="2015-06-16T05:55:36.397" Score="0" Body="&lt;p&gt;Ground speed can be determined by the vector sum of the aircraft's true &lt;a href=&quot;/questions/tagged/airspeed&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airspeed&amp;#39;&quot; rel=&quot;tag&quot;&gt;airspeed&lt;/a&gt; and the current &lt;a href=&quot;/questions/tagged/wind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wind&amp;#39;&quot; rel=&quot;tag&quot;&gt;wind&lt;/a&gt; speed and direction; a headwind subtracts from the ground speed, while a tailwind adds to it. Winds at other angles relative to the aircraft's &lt;a href=&quot;/questions/tagged/heading&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;heading&amp;#39;&quot; rel=&quot;tag&quot;&gt;heading&lt;/a&gt; will have not only a headwind/tailwind component, but also a &lt;a href=&quot;/questions/tagged/crosswind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;crosswind&amp;#39;&quot; rel=&quot;tag&quot;&gt;crosswind&lt;/a&gt; component.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airspeed indicator indicates the aircraft's speed relative to the air mass. The air mass may be moving over the ground due to wind, and, therefore, some additional means to provide position over the ground is required. This might be through navigation using landmarks, &lt;a href=&quot;/questions/tagged/radio-navigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;radio-navigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;radio-navigation&lt;/a&gt;, an &lt;a href=&quot;/questions/tagged/inertial-nav-system&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;inertial-nav-system&amp;#39;&quot; rel=&quot;tag&quot;&gt;inertial-nav-system&lt;/a&gt;, or GPS (occasionally called &lt;a href=&quot;/questions/tagged/gnss&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;gnss&amp;#39;&quot; rel=&quot;tag&quot;&gt;gnss&lt;/a&gt; instead). When more advanced technology is unavailable, an E6B flight computer may be used to calculate groundspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground speed is quite different from airspeed. When an aircraft is airborne, the ground speed does not determine when the aircraft will stall, and it doesn't influence &lt;a href=&quot;/questions/tagged/aircraft-performance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-performance&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-performance&lt;/a&gt; figures, such as rate of climb.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-11-15T09:08:50.673" LastActivityDate="2019-11-15T09:08:50.673" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15880" PostTypeId="4" CreationDate="2015-06-16T05:55:36.397" Score="0" Body="Ground speed is the horizontal speed of an aircraft relative to the ground. An aircraft heading vertically would have a ground speed of zero. Information displayed to passengers through the entertainment system often gives the aircraft's ground speed rather than its airspeed." OwnerUserId="8547" LastEditorUserId="22726" LastEditDate="2019-11-15T09:08:55.030" LastActivityDate="2019-11-15T09:08:55.030" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15881" PostTypeId="5" CreationDate="2015-06-16T05:56:44.943" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-16T05:56:44.943" LastActivityDate="2015-06-16T05:56:44.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15882" PostTypeId="4" CreationDate="2015-06-16T05:56:44.943" Score="0" Body="For questions about the processes and procedures used when operating aircraft" OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2016-07-08T14:36:05.413" LastActivityDate="2016-07-08T14:36:05.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15883" PostTypeId="5" CreationDate="2015-06-16T05:57:27.347" Score="0" Body="&lt;p&gt;Weight is the force of gravity acting on a mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and about one-sixth as much on the Moon. In this sense of weight, a body can be weightless only if it is far away (in principle infinitely far away) from any other mass. Although weight and mass are scientifically distinct quantities, the terms are often confused with each other in everyday discourse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a rival tradition within Newtonian physics and engineering which sees weight as that which is measured when one uses scales. There the weight is a measure of the magnitude of the reaction force exerted on a body. Typically, in measuring an object's weight, the object is placed on scales at rest with respect to the earth, but the definition can be extended to other states of motion. Thus, in a state of free fall, the weight would be zero. In this second sense of weight, terrestrial objects can be weightless. Ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, is weightless.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2015-06-16T06:24:11.713" LastActivityDate="2015-06-16T06:24:11.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15884" PostTypeId="4" CreationDate="2015-06-16T05:57:27.347" Score="0" Body="In science and engineering, the weight of an object is usually taken to be the force on the object due to gravity. Weight is a vector whose magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus: W = mg. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:35:41.117" LastActivityDate="2015-06-16T12:35:41.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15885" PostTypeId="5" CreationDate="2015-06-16T05:58:06.283" Score="0" Body="&lt;p&gt;In 1936, the airship Hindenburg offered passengers a piano, lounge, dining room, smoking room, and bar during the 2½ day flight between Europe and America. After the Second World War, IFE was delivered in the form of food and drink services, along with an occasional projector movie during lengthy flights. In 1985 the first personal audio player was offered to passengers, along with noise cancelling headphones in 1989. During the 1990s the demand for better IFE was a major factor in the design of aircraft cabins. Before then, the most a passenger could expect was a movie projected on a screen at the front of a cabin, which could be heard via a headphone socket at his or her seat.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1467" LastEditDate="2017-12-12T09:29:55.677" LastActivityDate="2017-12-12T09:29:55.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15886" PostTypeId="4" CreationDate="2015-06-16T05:58:06.283" Score="0" Body="In-flight entertainment (IFE) refers to the entertainment available to aircraft passengers during a flight. " OwnerUserId="8547" LastEditorUserId="1467" LastEditDate="2017-12-12T09:29:55.677" LastActivityDate="2017-12-12T09:29:55.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15887" PostTypeId="2" ParentId="15849" CreationDate="2015-06-16T05:58:59.390" Score="3" Body="&lt;p&gt;COST! What you need is a remote magnetic indicator. Some more advanced small planes have them. It's becoming less of the problem nowadays because even small airplanes get modern glass cockpits.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-06-16T05:58:59.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15888" PostTypeId="5" CreationDate="2015-06-16T05:59:39.243" Score="0" Body="&lt;p&gt;The checklist is developed to help aviators ensure they consider as much information as possible in the preflight phase so that they can make the best go/no-go decision possible and will be well-prepared once flying the flight where workload may constrain the ability to perform these tasks adequately. It is hoped that using this checklist, pilots can avoid the 5 P's: &quot;Poor Planning leads to Poor Pilot Performance&quot;. Using a checklist can help as an antidote to the &quot;impulsivity&quot; hazardous attitude and can improve performance when time is of the essence.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:51:56.740" LastActivityDate="2015-06-16T12:51:56.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15889" PostTypeId="4" CreationDate="2015-06-16T05:59:39.243" Score="0" Body="For questions about checklists used for operating aircraft." OwnerUserId="-1" LastEditorUserId="1696" LastEditDate="2016-07-08T14:31:44.280" LastActivityDate="2016-07-08T14:31:44.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15890" PostTypeId="5" CreationDate="2015-06-16T06:00:28.033" Score="0" Body="&lt;p&gt;Generally, aircraft are composed of a number of different materials and devices, including long and short carbon and glass fiber composites, wires, aluminum, titanium and steel alloys, foam, textiles and carpet, landing gears, fluids, electronic devices, engines, and other parts. Disposing off these parts safely (or sending them to be reused as spare parts on new in service aircraft) is called aircraft disposal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deserts, such as those in the Southwestern United States, are good locations for boneyards since the dry conditions reduce corrosion and the hard ground does not need to be paved. The largest facility of its kind, the 309th Aerospace Maintenance and Regeneration Group, is colloquially known as &quot;The Boneyard&quot;.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:23:41.193" LastActivityDate="2015-06-23T11:23:41.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15891" PostTypeId="4" CreationDate="2015-06-16T06:00:28.033" Score="0" Body="Generally, aircraft are composed of a number of different materials and devices, including long and short carbon and glass fiber composites, wires, aluminum, titanium and steel alloys, foam, textiles and carpet, landing gears, fluids, electronic devices, engines, and other parts. Disposing off these parts safely (or sending them to be reused as spare parts on new in service aircraft) is called aircraft disposal" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T13:08:30.793" LastActivityDate="2015-06-23T13:08:30.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15892" PostTypeId="5" CreationDate="2015-06-16T06:01:07.247" Score="0" Body="&lt;p&gt;Types having a small number of planes have specific names and are not usually described as multiplanes:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Biplane - two wings stacked one above the other.&#xA;Triplane - three wings stacked one above another.&#xA;Quadruplane- four stacked wings.&#xA;Tandem wing - two main planes, one behind the other. The tandem triple or tandem triplet configuration has three lifting surfaces one behind another.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;While triplane, quadruplane and tandem designs are relatively uncommon, aircraft with more than four sets of wings are rare, with none being successful.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:43:36.120" LastActivityDate="2015-06-16T12:43:36.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15893" PostTypeId="4" CreationDate="2015-06-16T06:01:07.247" Score="0" Body="In aviation, a multiplane is a fixed-wing aircraft configuration featuring multiple wing planes. The wing planes may be stacked one above another, or one behind another, or both in combination." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:42:43.320" LastActivityDate="2015-06-16T12:42:43.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15894" PostTypeId="5" CreationDate="2015-06-16T06:01:59.363" Score="0" Body="&lt;p&gt;It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms; that is, it models matter from a macroscopic viewpoint rather than from microscopic. Fluid mechanics, especially fluid dynamics, is an active field of research with many problems that are partly or wholly unsolved. Fluid mechanics can be mathematically complex, and can best be solved by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is devoted to this approach to solving fluid mechanics problems. Particle image velocimetry, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:33:31.157" LastActivityDate="2015-06-16T12:33:31.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15895" PostTypeId="4" CreationDate="2015-06-16T06:01:59.363" Score="0" Body="Fluid mechanics is the branch of physics which involves the study of fluids (liquids, gases, and plasmas) and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; and fluid dynamics, the study of the effect of forces on fluid motion. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T06:18:57.663" LastActivityDate="2015-06-16T06:18:57.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15896" PostTypeId="5" CreationDate="2015-06-16T06:03:28.710" Score="0" Body="&lt;p&gt;The aircraft design process is the engineering design process by which aircraft are designed. These depend on many factors such as customer and manufacturer demand, safety protocols, physical and economic constraints etc. For some types of aircraft the design process is regulated by national airworthiness authorities. This article deals with powered aircraft such as airplanes and helicopter designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft design is a compromise between many competing factors and constraints and accounts for existing designs and market requirements to produce the best aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:44:49.547" LastActivityDate="2015-06-23T11:44:49.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15897" PostTypeId="4" CreationDate="2015-06-16T06:03:28.710" Score="0" Body="Development of an aircraft from an On-Paper design to its final stage as a flyable plane is called Aircraft Development." OwnerUserId="8547" LastEditorUserId="8282" LastEditDate="2018-10-22T21:11:20.167" LastActivityDate="2018-10-22T21:11:20.167" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15898" PostTypeId="5" CreationDate="2015-06-16T06:04:03.077" Score="0" Body="&lt;p&gt;These systems can conserve fuel and extend engine life by metering the precise amount of fuel required to attain a specific target indicated air speed, or the assigned power for different phases of flight. A/T and AFDS (Auto Flight Director Systems) work together to fulfill the whole flight plan and greatly reduce the pilots' work load.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:42:21.960" LastActivityDate="2015-06-16T12:42:21.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15899" PostTypeId="4" CreationDate="2015-06-16T06:04:03.077" Score="0" Body="An autothrottle (automatic throttle) allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than manually controlling the fuel flow. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:35:25.807" LastActivityDate="2015-06-16T12:35:25.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15900" PostTypeId="5" CreationDate="2015-06-16T06:04:46.780" Score="0" Body="&lt;p&gt;Reversible propellers—those where the pitch can be set to negative values—can also create reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:55:30.037" LastActivityDate="2015-06-16T12:55:30.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15901" PostTypeId="4" CreationDate="2015-06-16T06:04:46.780" Score="0" Body="A controllable-pitch propeller (CPP) or variable-pitch propeller is a type of propeller with blades that can be rotated around their long axis to change the blade pitch." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:35:05.433" LastActivityDate="2015-06-16T12:35:05.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15902" PostTypeId="5" CreationDate="2015-06-16T06:05:21.730" Score="0" Body="&lt;p&gt;These uses often require exceptional performance, strength or heat resistance, even at the cost of considerable expense in their production or machining. Others are chosen for their long-term reliability in this safety-conscious field, particularly for their resistance to fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The field of materials engineering is an important one within aerospace engineering. Its practice is defined by the international standards bodies who maintain standards for the materials and processes involved. Engineers in this field may often have studied for degrees or post-graduate qualifications in it as a speciality.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:42:36.760" LastActivityDate="2015-06-16T12:42:36.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15903" PostTypeId="4" CreationDate="2015-06-16T06:05:21.730" Score="0" Body="Asp materials are materials, frequently metal alloys, that have either been developed for, or have come to prominence through, their use for aerospace purposes." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:55:50.197" LastActivityDate="2015-06-16T12:55:50.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15904" PostTypeId="5" CreationDate="2015-06-16T06:06:18.497" Score="0" Body="&lt;p&gt;To prevent such an aircraft approaching the stall the aircraft designer may install a hydraulic or electro-mechanical device that pushes forward on the elevator control system whenever the aircraft’s angle of attack reaches the pre-determined value, and then ceases to push when the angle of attack falls sufficiently. A system for this purpose is known as a stick pusher.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T13:07:39.413" LastActivityDate="2015-06-16T13:07:39.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15905" PostTypeId="4" CreationDate="2015-06-16T06:06:18.497" Score="0" Body="A stick pusher is a device installed in some fixed-wing aircraft to prevent the aircraft from entering an aerodynamic stall. Some large fixed-wing aircraft display poor post-stall handling characteristics or are vulnerable to deep stall. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-16T12:28:54.037" LastActivityDate="2015-06-16T12:28:54.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15906" PostTypeId="2" ParentId="15847" CreationDate="2015-06-16T06:11:27.763" Score="8" Body="&lt;p&gt;The callsign is the combination of the ICAO Radio Telephony (R/T) designator and a flight specific identifier consisting of numbers and letters. In addition to the R/T designator there is also a three letter designator used on flight plans and air traffic control display systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The R/T designator (callsign) must not cause confusion with other operators flying in the same area, preferably at most three syllables long and it must be pronounceable in at least one of the following languages; English, French, Spanish or Russian.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since there are many operators that have &quot;airline&quot; or &quot;airways&quot; in their name, that word is usually avoided in the R/T designator as it easily causes confusion. Usually an alternative is found that is in some way related to the airline. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For pilots it is not too difficult, they are typically paying attention specifically to their own R/T callsign. For controllers it is more difficult since they have to associate the three letter code on their screen with R/T designators that are not related in an obvious way.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="7532" LastEditDate="2015-06-16T12:46:44.280" LastActivityDate="2015-06-16T12:46:44.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15907" PostTypeId="5" CreationDate="2015-06-16T07:06:51.033" Score="0" Body="&lt;p&gt;A sailplane is a kind of glider, with conventional aerodynamic control surfaces, intended to be able to soar.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="34686" LastEditDate="2021-04-22T16:29:23.837" LastActivityDate="2021-04-22T16:29:23.837" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15908" PostTypeId="4" CreationDate="2015-06-16T07:06:51.033" Score="0" Body="Use with [glider] for sailplanes: a type of glider intended for soaring and designed with conventional aerodynamic control surfaces, else use [glider] only." OwnerUserId="8547" LastEditorUserId="14897" LastEditDate="2021-04-22T16:11:58.683" LastActivityDate="2021-04-22T16:11:58.683" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15913" PostTypeId="2" ParentId="15763" CreationDate="2015-06-16T08:37:01.443" Score="3" Body="&lt;p&gt;While commercial aircraft can obviously be used for transport missions (transporting troops or military cargo) unchanged, I believe the question is really about using commercial airliners for combat missions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not entirely sure if light business jets like the Learjet 35 meet the definition of a 'commercial airliner' in the question, but these civilian aircraft have been &lt;a href=&quot;https://en.wikipedia.org/wiki/Escuadr%C3%B3n_F%C3%A9nix&quot; rel=&quot;nofollow&quot;&gt;pressed into service&lt;/a&gt; for military missions during the Falklands war.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Learjet also make military versions of 35 series; the primary change being the addition of hard points under the wings allowing the carrying of military payloads including weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar conversions include the older turboprop Fokker F27 conversion:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.combataircraft.com/en/Military-Aircraft/Fokker/F-27-Enforcer/&quot; rel=&quot;nofollow&quot;&gt;http://www.combataircraft.com/en/Military-Aircraft/Fokker/F-27-Enforcer/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So aircraft can be lightly modified to perform combat missions if they have the ability to carry external loads and some avionics to support the loads. However such aircraft would lack features found in military aircraft such as ejection seats.&lt;/p&gt;&#xA;" OwnerUserId="8905" LastEditorUserId="923" LastEditDate="2015-06-16T13:16:48.143" LastActivityDate="2015-06-16T13:16:48.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15914" PostTypeId="1" AcceptedAnswerId="15918" CreationDate="2015-06-16T12:49:25.400" Score="3" ViewCount="5110" Body="&lt;p&gt;Do private jets have relaxed FAA regulations (and regulations imposed by any other aviation agency) when compared to commercial jets? If yes, which aspects of aviation are these relaxations are pertaining to?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1696" LastEditDate="2015-06-16T19:57:33.397" LastActivityDate="2016-12-16T11:13:42.083" Title="Are regulations covering private jets different from those covering commercial jets?" Tags="&lt;faa-regulations&gt;&lt;private-jets&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15915" PostTypeId="2" ParentId="15763" CreationDate="2015-06-16T13:21:42.487" Score="3" Body="&lt;p&gt;For what its worth &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Force_One&quot; rel=&quot;nofollow&quot;&gt;Air Force One&lt;/a&gt; is operated by the United States Air Force and is built on the common 747 airframe. Although the plane is highly customized and lets be honest only servers a single military purpose it is, for what its worth a civilian plane (in a sense) that has been converted to a military function. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-16T13:21:42.487" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15916" PostTypeId="2" ParentId="15914" CreationDate="2015-06-16T13:41:18.643" Score="5" Body="&lt;p&gt;Depending on what you are looking for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=98948370fc90e2d59ff16122f0fd25ff&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5&quot;&gt;Here&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=98948370fc90e2d59ff16122f0fd25ff&amp;amp;mc=true&amp;amp;node=pt14.3.135&amp;amp;rgn=div5#se14.3.135_11&quot;&gt;here&lt;/a&gt; are the requirements for operating as an air carrier. All air carriers from the large airlines to the smaller charter situations must follow the same rules so to speak. The rules generally draw the line at accepting/paying money to fly or be flown in an aircraft respectively (as I understand it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you own a large jet aircraft (fully or fractionally) take a look &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1850de6d7c2076ada0e7c665d3d999ec&amp;amp;mc=true&amp;amp;node=pt14.2.91&amp;amp;rgn=div5#se14.2.91_1501&quot;&gt;here&lt;/a&gt; for more information on how that's governed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.501   Applicability.&lt;/strong&gt;&#xA;  (a) This subpart prescribes operating rules, in addition to those prescribed in other subparts of this part, governing the operation of large airplanes of U.S. registry, turbojet-powered multiengine civil airplanes of U.S. registry, and fractional ownership program aircraft of U.S. registry that are operating under subpart K of this part in operations not involving common carriage. The operating rules in this subpart do not apply to those aircraft when they are required to be operated under parts 121, 125, 129, 135, and 137 of this chapter. (Section 91.409 prescribes an inspection program for large and for turbine-powered (turbojet and turboprop) multiengine airplanes and turbine-powered rotorcraft of U.S. registry when they are operated under this part or part 129 or 137.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the end of the day it falls on the pilot in command to make sure that their &lt;em&gt;aircraft is airworthy&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you hone in a bit more on a specific question you would like answered we can try to aid you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some varying &lt;em&gt;certifications&lt;/em&gt; for &lt;em&gt;specific&lt;/em&gt; smaller jets that allow them to be operated a little differently than a commercial airliner. The vast majority of commercial jets require 2 pilots however there are smaller jets like &lt;a href=&quot;http://cessna.txtav.com/en/citation/mustang&quot;&gt;the Citation Mustang&lt;/a&gt; that are certified for &lt;a href=&quot;http://www.flyingmag.com/single-pilot-jets&quot;&gt;single pilot operations&lt;/a&gt; and geared mainly towards the private jet crowd. So that might be what you are looking for, but that's the only one I can think of off hand.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2015-06-16T15:14:10.750" LastActivityDate="2015-06-16T15:14:10.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15917" PostTypeId="2" ParentId="15816" CreationDate="2015-06-16T14:55:02.733" Score="10" Body="&lt;p&gt;The spinning blades in the compressor stage of a jet engine or turbo fan are themselves airfoils, like the aircraft's wings. The operation of the engine depends on the smooth flow of air over the blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just like a wing, an individual blade, or a small component of one, can experience an airfoil &quot;stall&quot;, where the air flow over the blade separates into a cell of &quot;stuck&quot;, highly turbulent air behind the blade, and the air flows around the cell instead of smoothly around the blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a flow separation occurs, the airfoil's ability to push the air in proper direction at the right flow rate—and thereby contribute to the compression of air behind the fan assembly—is inhibited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since these blades are rotating, the blade quickly moves away from the packet of stagnant air. Of course the stalled air packet has some momentum from the intake air, and it will experience a drift along with the rotating blade, but it is not moving with the average flow of the air through the engine anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus the next blade spinning round tends to encounter the stalled air packet. If the stalled air cell is not particularly large, it may be absorbed by the air flow at this stage and dissipated. Alternatively, it might be large enough to stall the subsequent blade as well. At this point, it is called a &quot;rotational stall&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the stall continues to propagate, the ability of the fan stage to deliver air to the subsequent compression stage is impeded, and it will lead to an abrupt drop in pressure inside the combustion chamber. This causes a reduction in available oxygen for combustion. The engine's performance, measured by the thrust delivered, is strongly impaired, and there is likely to be a lot of unburnt fuel remaining after the oxygen in the compressor is exhausted. That unburnt fuel may ignite in a bright exterior flame as it escapes out the back of the combustion chamber and mixes with the oxygen-rich bypass flow, or in the case of a jet engine, after it exits the engine altogether.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drop in back pressure in the compressor will, under normal conditions, enable the compressor fan blades to begin operating as proper air foils again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An alternative type of stall is a compressor surge. In this case, the problem is caused by unexpectedly high pressure in the combustion chamber (or in the compressor), which forces its way forward as well as backwards, against the incoming flow rate. Again, this disrupts the operation of the compressor blades as airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See Advanced Control of Turbofan Engines by Hanz Richte&lt;/p&gt;&#xA;" OwnerUserId="8565" LastActivityDate="2015-06-16T14:55:02.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15918" PostTypeId="2" ParentId="15914" CreationDate="2015-06-16T16:55:52.547" Score="14" Body="&lt;p&gt;Technically no, but in the spirit of your question, yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircraft, including those operated for private and commercial purposes, are governed by 14 CFR 91 - General Operating and Flight Rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 119 specifies additional regulations that govern certain types of aircraft and operations, including larger private aircraft and commercial operations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;14 CFR 125 covers larger (airline style) private aircraft&lt;/li&gt;&#xA;&lt;li&gt;14 CFR 121 covers the airlines&lt;/li&gt;&#xA;&lt;li&gt;14 CFR 135 covers commuter and on demand (charter) commercial operators&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So it isn't that private aircraft have relaxed regulations, it is just that they aren't required to comply with the &lt;strong&gt;additional&lt;/strong&gt; regulations that govern the airline and charter operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many, MANY additional regulations that commercial operators have to comply with, including operational and maintenance regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few example:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilots flying commercially have strict limits on the time that they are allowed to fly or be on duty.  Pilots of private aircraft don't have any limit, other than not to fly if it would be unsafe.&lt;/li&gt;&#xA;&lt;li&gt;Commercial pilots are subject to more strict medical requirements.&lt;/li&gt;&#xA;&lt;li&gt;If an aircraft has to divert due to a mechanical problem, it must be reported to the FAA if being operated commercially.&lt;/li&gt;&#xA;&lt;li&gt;There are strict limits on how far that a commercially operated aircraft may be from a suitable airport, but there are no such limits for privately operated aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Passengers must be screened and must be checked against government maintained no-fly lists for commercial flights.&lt;/li&gt;&#xA;&lt;li&gt;An aircraft used for commercial purposes is required to be inspected more often.&lt;/li&gt;&#xA;&lt;li&gt;With certain (very limited) exceptions, commercial aircraft are required to be operated by a company (certificate holder) with required management personnel such as the Chief Pilot and Director of Maintenance, while private aircraft can be managed by one person (even the pilot).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See the online &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=cfdcf654f5be63a6eb38ba557c846ca5&amp;amp;mc=true&amp;amp;tpl=/ecfrbrowse/Title14/14cfrv3_02.tpl#0&quot; rel=&quot;noreferrer&quot;&gt;eCFR&lt;/a&gt; for the specific regulations that fall under each part.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-06-17T20:05:39.117" LastActivityDate="2015-06-17T20:05:39.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15919" PostTypeId="2" ParentId="15813" CreationDate="2015-06-16T17:40:01.423" Score="13" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZClLs.jpg&quot; alt=&quot;Convair 880 with cargo door open.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes they can, here's a Convair 880 with cargo door open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XNIN2.jpg&quot; alt=&quot;DC-8 with Door open&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DC-8 with cargo door open.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-17T16:31:54.560" LastActivityDate="2015-06-17T16:31:54.560" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="15920" PostTypeId="2" ParentId="15835" CreationDate="2015-06-16T18:01:11.243" Score="6" Body="&lt;p&gt;The difference in security measures is due to the difference in the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial airlines could carry almost anyone as passengers. Although some amount of security is done on the ground, and in the air, a cockpit door is still a useful line of defense. It's difficult to verify the intentions or capabilities of everyone that will ever be a passenger on the plane. Also, aside from limited circumstances, there is no reason for anyone from the cabin to be accessing the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Private jets are different, because they are just that; private. A business or individual has the responsibility to clear their passengers before a flight. If they feel that there may be an issue, they can certainly have a cockpit door. But that situation is not normal. On a private jet, the passengers may comprise of the owner and his or her guests. As a matter of courtesy they may want to visit the cockpit. On a business flight, the circumstances would be similar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/15846/1696&quot;&gt;paul pointed out&lt;/a&gt;, these planes typically don't have the range or size to be capable of the same things an airliner would be. And the larger the plane, the larger the price tag. This would cost much more than just a commercial ticket, which also serves as a form of security.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large jets will also have additional security added: &lt;a href=&quot;https://aviation.stackexchange.com/q/3541/1696&quot;&gt;What are the security measures preventing someone from chartering a 747 and using it to commit a terrorist attack?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="8282" LastEditDate="2019-06-23T20:18:45.560" LastActivityDate="2019-06-23T20:18:45.560" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15921" PostTypeId="2" ParentId="15835" CreationDate="2015-06-16T18:40:43.453" Score="23" Body="&lt;p&gt;The same thing that prevents the passengers in your car from hijacking it and using it to run people down or drive it through a mall:  It's your private car and you generally know the people that you let in to it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same applies to private aircraft.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-06-16T18:40:43.453" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="15922" PostTypeId="2" ParentId="588" CreationDate="2015-06-16T19:16:01.437" Score="2" Body="&lt;p&gt;The rules come from a basis at the FAA that a serious accident is one with multiple fatalities, not just one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From AC-1309:&#xA;Catastrophic: Failure conditions that are expected to result in multiple fatalities of the occupants...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft that have only one seat do not need to be designed / certified as stringently as aircraft with 2+ seats. Along with that, if only one person is in the plane, you can't have multiple fatalities, so there's no such thing as a catastrophic risk.&lt;/p&gt;&#xA;" OwnerUserId="8912" LastActivityDate="2015-06-16T19:16:01.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15925" PostTypeId="2" ParentId="15855" CreationDate="2015-06-16T22:12:30.883" Score="3" Body="&lt;p&gt;Denver International has Cat III approaches to all 4 north runways (35L/R, 34L/R), and I have never heard of any Cat III certification requirements specific to that airport. As far as I know, the answer to the question is &quot;no,&quot; since nothing special happens at or near 2500' &lt;em&gt;MSL&lt;/em&gt; that affects Cat III operations.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2019-02-15T11:45:16.860" LastActivityDate="2019-02-15T11:45:16.860" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="15926" PostTypeId="1" AcceptedAnswerId="15978" CreationDate="2015-06-16T23:04:02.020" Score="10" ViewCount="944" Body="&lt;p&gt;&lt;sub&gt;No offense to any pilots, I am a student, curious.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just watched &lt;a href=&quot;http://www.imdb.com/title/tt3079380/&quot; rel=&quot;noreferrer&quot;&gt;Spy (2015)&lt;/a&gt; and I was just wondering what happens if one of the pilot accidentally sneezes during a difficult maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/S5oFX.jpg&quot; alt=&quot;one of the good guys sneezes during a critical stand-off&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;sup&gt;Jude Law misfires during a critical stand-off.&lt;/sup&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean what are the preventive measures taken to avoid this - the jet is obviously primed to be in best of its agility &amp;amp; stick-sensitiveness so can the pilots selectively decrease sensitivity of stick when needed?&lt;/p&gt;&#xA;" OwnerUserId="8215" LastEditorUserId="3386" LastEditDate="2019-10-09T08:11:04.380" LastActivityDate="2019-10-09T08:11:04.380" Title="What if a aerobatic fighter pilot sneezes in middle of a maneuver?" Tags="&lt;safety&gt;&lt;flight-controls&gt;&lt;flight-instruments&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15927" PostTypeId="2" ParentId="15926" CreationDate="2015-06-17T00:00:50.930" Score="8" Body="&lt;p&gt;As Ralph J alluded to it in a comment, I would guess this is extremely rare.  I have never experienced this during any of my time.  Maybe one of the higher time guys (Rhino Driver?) will pipe in here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess if you did have to sneeze, let off the stick, sneeze, then clean your mask out (if you didn't already take it off).  If you were in a critical phase of flight, then deal with it and keep flying the jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nothing to it really...&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-17T00:00:50.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15928" PostTypeId="1" CreationDate="2015-06-17T00:17:30.233" Score="4" ViewCount="252" Body="&lt;p&gt;I've been following aviation for the last 20 years and have seen particularly since the last 10 a lot of talk of aero-diesel engines for light aircraft. The idea being they're cheaper to run using Avtur rather than expensive Avgas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm surprised that in 10 years since I first really saw this mentioned not much has changed. There are a few new aircraft available and retrofits, but by and large engines are still traditional in new aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it likely that aero-diesels will replace traditional aircraft engines any time soon? &lt;/p&gt;&#xA;" OwnerUserId="8880" LastActivityDate="2015-06-17T00:17:30.233" Title="Will Aerodiesel engines replace Avgas engines?" Tags="&lt;piston-engine&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-06-17T02:20:04.273" ContentLicense="CC BY-SA 3.0" />
  <row Id="15929" PostTypeId="2" ParentId="15763" CreationDate="2015-06-17T01:29:03.057" Score="3" Body="&lt;p&gt;Aircraft development seems to go the other way more often. Example: the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot; rel=&quot;nofollow&quot;&gt;Boeing 377 Stratocruiser&lt;/a&gt; was developed (indirectly) from the WWII B-29 bomber. It's expensive to develop a new platform; military budgets seem to be large enough for such undertakings on a frequent basis. Not so in the commercial world. Revolutionary designs like the B-707 and B-747 come along, but even they were started with military contracts in mind as much as civilian markets.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2015-06-17T01:29:03.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15930" PostTypeId="1" AcceptedAnswerId="15931" CreationDate="2015-06-17T02:32:44.883" Score="7" ViewCount="519" Body="&lt;p&gt;If a person exchanges email with a private pilot (who normally operates under FAR 91) with a view towards hitching a ride or taking an empty leg flight, does this act mean that the pilot must then operate under FAR 135?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or alternatively, if there is no discussion of payment and/or barter, would the ride still take place under FAR 91?  I have watched the demise of AirPooler, but this was a much more structured arrangement which blatantly  &lt;em&gt;invited&lt;/em&gt; scrutiny from the regulator.  This question assumes there is no intermediary like AirPooler or BlackJet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am trying to find out what actually triggers an escalation in the rules.  FAA would be fine, but anything on European regulators would be massively welcomed.  I am UK based, not a pilot, and use empty leg on occasion, so I might be affected if the European regulators follow the FAA's lead.  Knowing the trigger point is key.&lt;/p&gt;&#xA;" OwnerUserId="8908" LastEditorUserId="1696" LastEditDate="2015-06-17T15:53:35.910" LastActivityDate="2015-06-17T17:02:52.787" Title="How does email communication with a private pilot affect FAA rules on compensation?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;private-jets&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15931" PostTypeId="2" ParentId="15930" CreationDate="2015-06-17T03:09:06.090" Score="7" Body="&lt;p&gt;I'll answer it from the FAA since that's what I know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=40760189a03dfea0b501608f33820a45&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#se14.2.61_1113&quot; rel=&quot;nofollow&quot;&gt;FAR&lt;/a&gt; is pretty clear on the matter here  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Except as provided in paragraphs (b) through (h) of this section, no person who holds a private pilot certificate may act as pilot in command of an aircraft that is carrying passengers or property for compensation or hire; nor may that person, for compensation or hire, act as pilot in command of an aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However if you want to split the cost evenly, you can:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For what it's worth I would say you can still operate under Part 91 in the case you have outlined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the FAA prevents a PPL holder from receiving any kind of compensation for a flight. &lt;a href=&quot;http://www.bloomberg.com/news/articles/2014-08-15/flight-share-deemed-illegal-by-faa-in-blow-to-airpooler&quot; rel=&quot;nofollow&quot;&gt;This Article&lt;/a&gt; talks about some of the points that the FAA discussed when shutting down these services. The issue with some of these sharing services is that the middle man (AirPooler) and the like &lt;a href=&quot;http://techcrunch.com/2014/04/02/airpooler/&quot; rel=&quot;nofollow&quot;&gt;take a fee&lt;/a&gt;, this seems like the aspect that the FAA had an issue with since although the pilot was not profiting per se, someone was, this seems to be the FAA trigger. I don't know much about the deep aspects of the law but I'm sure there are things that can also arise with being a middleman/deal broker of these kinds of things.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="4474" LastEditDate="2015-06-17T17:02:52.787" LastActivityDate="2015-06-17T17:02:52.787" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15932" PostTypeId="1" CreationDate="2015-06-17T03:40:12.473" Score="3" ViewCount="146" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xBpqz.jpg&quot; alt=&quot;Zeppelin Avionics&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm hoping to learn more about this avionics pictue, with a plan to redesign the user interface. Would someone be willing to share other pictures, along with descriptions of each data point?&lt;/p&gt;&#xA;" OwnerUserId="8921" LastActivityDate="2015-06-17T03:40:12.473" Title="Would someone please describe or explain airship or zeppelin avionics packages" Tags="&lt;flight-controls&gt;&lt;avionics&gt;&lt;radar&gt;" AnswerCount="0" CommentCount="2" FavoriteCount="1" ClosedDate="2015-06-17T06:27:56.183" ContentLicense="CC BY-SA 3.0" />
  <row Id="15933" PostTypeId="1" AcceptedAnswerId="15959" CreationDate="2015-06-17T04:12:37.137" Score="24" ViewCount="8883" Body="&lt;p&gt;Shock waves resulting from low intensity explosions can easily &lt;a href=&quot;https://en.wikipedia.org/wiki/Table_of_explosive_detonation_velocities&quot;&gt;reach&lt;/a&gt; 10,000m/s.  About 5% of the energy released in a nuclear air burst is in the form of ionizing radiation: neutrons, gamma rays, alpha particles and electrons moving at speeds up to the &lt;strong&gt;speed of light&lt;/strong&gt; (thus, carrying a hell of a lot of energy).  With these stats it appears that for the bomber as well, a nuclear bomb is very bad. How are they protected? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2015-06-17T16:49:37.427" LastActivityDate="2018-01-17T08:20:04.600" Title="Are nuclear bombers themselves damaged after dropping bombs?" Tags="&lt;bomber&gt;&lt;strategic-bomber&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15934" PostTypeId="2" ParentId="15775" CreationDate="2015-06-17T06:20:01.837" Score="2" Body="&lt;p&gt;I can't speak for the Blue Angels, but there are some airplanes that have this feature: &lt;strong&gt;those equipped with a DFC100 autopilot&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XerDh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-06-17T06:20:01.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15935" PostTypeId="5" CreationDate="2015-06-17T06:22:32.003" Score="0" Body="&lt;p&gt;Smoke detectors are typically housed in a disk-shaped plastic enclosure about 150 millimetres (6 in) in diameter and 25 millimetres (1 in) thick, but the shape can vary by manufacturer or product line. Most smoke detectors work either by optical detection (photoelectric) or by physical process (ionization), while others use both detection methods to increase sensitivity to smoke. Sensitive alarms can be used to detect, and thus deter, smoking in areas where it is banned. Smoke detectors in large commercial, industrial, and residential buildings are usually powered by a central fire alarm system, which is powered by the building power with a battery backup. However, in many single-family detached and smaller multiple family housings, a smoke alarm is often powered only by a single disposable battery&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:22:39.440" LastActivityDate="2015-06-17T12:22:39.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15936" PostTypeId="4" CreationDate="2015-06-17T06:22:32.003" Score="0" Body="A smoke detector is a device that senses smoke, typically as an indicator of fire. Commercial and residential security devices issue a signal to a fire alarm control panel as part of a fire alarm system, while household detectors, known as smoke alarms, generally issue a local audible or visual alarm from the detector itself." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:23:00.493" LastActivityDate="2015-06-17T12:23:00.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15937" PostTypeId="5" CreationDate="2015-06-17T06:25:02.233" Score="0" Body="&lt;p&gt;The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the flight deck. The official U.S. Navy term for these vessels is &quot;aviation-capable ships&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Early flight decks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first flight decks were inclined wooden ramps built over the forecastle of naval warships. Eugene Ely made the first fixed-wing aircraft take-off from a warship from USS Birmingham on 14 November 1910. Two months later, on 18 January 1911, Ely landed his Curtiss pusher plane on a platform on Pennsylvania anchored in San Francisco Bay using the first tailhook system, designed and built by circus performer and aviator Hugh Robinson. Ely told a reporter: &quot;It was easy enough. I think the trick could be successfully turned nine times out of ten.&quot; On 9 May 1912, Commander Charles Samson became the first man to take off from a ship which was underway when he flew his Short S.27 off of HMS Hibernia, which was steaming at 10.5 kn (12.1 mph; 19.4 km/h). Because the take-off speed of early aircraft was so low, it was possible for an aircraft to make a very short take off when the launching ship was steaming into the wind. Later, removable &quot;flying-off platforms&quot; appeared on the gun turrets of battleships and battlecruisers starting with HMS Repulse, allowing aircraft to be flown off for scouting purposes, although there was no chance of recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On 2 August 1917, while performing trials, Squadron Commander E.H. Dunning landed a Sopwith Pup successfully on board the flying-off platform of HMS Furious, becoming the first person to land an aircraft on a moving ship. However, on his third attempt, a tire burst as he attempted to land, causing the aircraft to go over the side, killing him; thus Dunning also has the dubious distinction of being the first person to die in an aircraft carrier landing accident. The landing arrangements on Furious were highly unsatisfactory. In order to land, aircraft had to manoeuvre around the superstructure. Furious was therefore returned to dockyard hands to have a 300 ft (91 m) deck added aft for landing, on top of a new hangar. The central superstructure remained, however, and turbulence caused by it badly affected the landing deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Full length decks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first aircraft carrier that began to show the configuration of the modern vessel was the converted liner HMS Argus, which had a large flat wooden deck added over the entire length of the hull, giving a combined landing and take-off deck unobstructed by superstructure turbulence. Because of her unobstructed flight deck, Argus had no fixed conning tower and no funnel. Rather, exhaust gases were trunked down the side of the ship and ejected under the fantail of the flight deck (which, despite arrangements to disperse the gases, gave an unwelcome &quot;lift&quot; to aircraft immediately prior to landing). The lack of a command position and funnel was unsatisfactory, and Argus was used to experiment with various ideas to remedy the solution. A photograph in 1917 shows her with a canvas mock-up of a starboard &quot;island&quot; superstructure and funnel. This was placed on the starboard side because the rotary engines of some early aircraft created torque which pulled the nose left, meaning an aircraft naturally yawed to port on take-off; therefore, it was desirable that they turned away from the fixed superstructure. This became the typical aircraft carrier arrangement and was used in the next British carriers, HMS Hermes and Eagle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After World War I, battlecruisers that otherwise would have been discarded under the Washington Naval Treaty—such as the British Furious and Glorious-class and the American USS Lexington and Saratoga—were converted to carriers along the above lines. Being large and fast they were perfectly suited to this role; the heavy armoring and scantlings and low speed of the converted battleship Eagle served to be something of a handicap in practice. Because the military effectiveness of aircraft carriers was then unknown, early ships were typically equipped with cruiser-calibre guns to aid in their defense if surprised by enemy warships. These guns were generally removed in World War II and replaced with anti-aircraft guns, as carrier doctrine developed the &quot;task force&quot; (later called &quot;battle group&quot;) model, where the carrier's defense against surface ships would be a combination of escorting warships and its own aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ships of this configuration, the hangar deck was the strength deck and an integral part of the hull, and the hangar and light steel flight deck were considered to be part of the superstructure. Such ships were still being built into the late 1940s, classic examples being the U.S. Navy's Essex and Ticonderoga-class carriers. However, in 1936, the Royal Navy began construction of the Illustrious-class. In these ships, the flight deck was the strength deck, an integral part of the hull, and was heavily armored to protect the ship and her air complement. The flight deck as the strength deck was adopted for later construction. This was necessitated by the ever-increasing size of the ships, from the 13,000 ton USS Langley in 1922 to over 100,000 tons in the latest Nimitz-class carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Armored decks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aircraft carriers supplanted battleships as the primary fleet capital ship, there were two schools of thought on the question of armor protection being included into the flight deck. The USN initially favored unarmored flight decks because they maximized aircraft carrier hangar and flight deck size, which in turn maximized aircraft capacity in the hangar, and on the flight deck, in the form of a permanent &quot;deck park&quot; for a large proportion of the aircraft carried. In 1936 the Royal Navy developed the armored flight deck aircraft carrier which also enclosed the hangar sides and ends with armor. The addition of armor to the flight deck offered aircraft below some protection against aerial bombs while the armored hangar sides and ends helped to minimize damage and casualties from explosions or fires within or outside the hangar. The addition of armor to the hangar forced a reduction in top-weight, so the hangar height was reduced, and this restricted the types of aircraft that these ships could carry, although the Royal Navy's armored carriers did carry spare aircraft in the hangar overheads. The armor also reduced the length of the flight deck, reducing the maximum aircraft capacity of the armored flight deck aircraft carrier. Additionally, Royal Navy aircraft carriers did not use a permanent deck park until approximately 1943; before then the aircraft capacity of RN aircraft carriers was limited to their hangar capacity. The 23,000 ton British Illustrious-class had a hangar capacity for 36 Swordfish sized aircraft and a single 458 ft x 62 ft x 16 ft ( 140m x 19m x 4.8m) hangar, but carried up to 57 aircraft with a permanent deck park while the 23,400 ton Implacable class featured increased hangar capacity with a 458 ft x 62 ft x 14 ft ( 140m x 19m x 4.3m) upper hangar and the addition of a 208 ft by 62 ft by 14 ft (63m x 19m x 4.3m) lower hangar, forward of the after elevator, which had a total capacity of 52 Swordfish sized aircraft or a mix of 48 late war aircraft in the hangar plus 24 aircraft in a permanent deck park, but carried up to 81 aircraft with a deck park. The 27,500 ton USN Essex class had a 654 ft x 70 ft x 17.5 ft (198m x 21m x 5.3m) hangar that was designed to handle a mix of 72 prewar USN aircraft. but carried up to 104 late war aircraft using both the hangar and a permanent deck park. The experience of World War II caused the USN to change their design policy in favor of armored flight decks on much larger ships: &quot;The main armor carried on Enterprise is the heavy armored flight deck. This was to prove a significant factor in the catastrophic fire and explosions that occurred on Enterprise's flight deck in 1969. The US Navy learned its lesson the hard way during World War II when all its carriers had only armored hangar decks. All attack carriers built since the Midway class have had armored flight decks.&quot;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T13:09:32.063" LastActivityDate="2015-06-23T13:09:32.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15938" PostTypeId="4" CreationDate="2015-06-17T06:25:02.233" Score="0" Body="The flight deck of an aircraft carrier is the surface from which its aircraft take off and land, essentially a miniature airfield at sea. On smaller naval ships which do not have aviation as a primary mission, the landing area for helicopters and other VTOL aircraft is also referred to as the flight deck. The official U.S. Navy term for these vessels is &quot;aviation-capable ships&quot;." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T13:09:22.993" LastActivityDate="2015-06-23T13:09:22.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15939" PostTypeId="5" CreationDate="2015-06-17T06:26:41.727" Score="0" Body="&lt;p&gt;Most Touring Motor Gliders (TMGs) are designed with engines of 80 to 100 hp (75 kW) and typically cruise (under power) at 85–100 knots (190 km/h). Most have fuel tanks capable of holding 50 and up to 100 liters (13 to 26 US gallons) of fuel, giving a range under power of up to 450 nautical miles (approximately 830 kilometers). Modern TMGs like the Phoenix Air Phoenix are capable of higher speeds and longer range under power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some TMGs are equipped with folding wings to allow them to fit in standard small airplane T-hangars. Tow hooks are unnecessary, since aircraft with self-launch ability do not require access to winch or tow plane for launching like a conventional glider.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some TMGs, like the Europa or the Phoenix, can also be supplied with interchangeable wings or wingtips so that they can be flown as a standard touring aircraft as well as a TMG.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The landing gear configuration on TMGs usually incorporates two fixed main wheels, allowing it to be taxied on the ground without a wing walker. While some TMGs have only one main wheel, with auxiliary trolley wheels on the wings for taxiing, it is becoming more common to find them being manufactured with tricycle and conventional (two fixed main wheels – i.e. a &quot;tail-dragger&quot;) landing gear configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the additional drag of the stopped propeller and landing gear reduces their gliding performance, TMGs are seldom used in competition.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1961" LastEditDate="2015-06-17T09:04:05.637" LastActivityDate="2015-06-17T09:04:05.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15940" PostTypeId="4" CreationDate="2015-06-17T06:26:41.727" Score="0" Body="Glider aircraft equipped with a motor with fixed or full feathering propellers are generally classified as Touring Motor Gliders (TMGs). TMGs can take off and cruise like an airplane or soar with power off, like a glider.&#xD;&#xA;&#xD;&#xA;They are fitted with front-mounted engines, similar to a small airplane. The large wingspans of TMGs provide a moderate gliding performance, not as good as that of unpowered gliders. " OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2015-06-17T07:15:19.803" LastActivityDate="2015-06-17T07:15:19.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15941" PostTypeId="1" CreationDate="2015-06-17T06:37:59.030" Score="3" ViewCount="1165" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems#Solution&quot; rel=&quot;nofollow&quot;&gt;Wikipedia's B787 article&lt;/a&gt; states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The causes of the battery failures are still unknown. There is still concern that because the root cause of the fires were not identified, the solutions put in place by Boeing will not be able to cover the full range of possible failure modes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But 787 was still cleared for flight after it fixed the &quot;Fire Propagation&quot; problem by correctly packaging its batteries in a fire resistant material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is :&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the actual cause of such Battery problems? (If it's known?)&lt;/li&gt;&#xA;&lt;li&gt;If Boeing is not able to resolve the root cause of the fires (according to Wikipedia), then is it safe for the Dreamliner to be allowed to fly?&lt;br&gt;&#xA;&lt;em&gt;Because what they have done to resolve the problem does not appear to be a permanent solution, but more of a temporary fix.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8482" LastEditDate="2015-06-27T13:57:04.330" LastActivityDate="2015-06-27T13:57:04.330" Title="The root cause for Boeing 787 Dreamliner battery problems" Tags="&lt;safety&gt;&lt;boeing-787&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-06-17T14:52:50.893" ContentLicense="CC BY-SA 3.0" />
  <row Id="15942" PostTypeId="1" AcceptedAnswerId="15966" CreationDate="2015-06-17T06:43:29.580" Score="8" ViewCount="11547" Body="&lt;p&gt;When we say that a missile has been locked on a target (lets assume a fast moving target, and that the missile is mounted on a fast moving plane), we assume that once the missile has been locked onto the target, it will actually hit the target after firing (Irrespective of the subsequent changes in the position, velocity and acceleration of the target). How does this system work?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="3386" LastEditDate="2018-04-24T12:50:47.047" LastActivityDate="2018-04-24T12:50:47.047" Title="How does a Missile Lock Work?" Tags="&lt;military&gt;&lt;missiles&gt;&lt;missile-lock&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15943" PostTypeId="5" CreationDate="2015-06-17T06:45:39.910" Score="0" Body="&lt;p&gt;In the post-WWII era, the term became more widely used in connection to missile guidance concepts. Many modern anti-aircraft missiles use some form of semi-active radar homing, where the missile seeker listens for reflections of the launch platform's main radar. To provide a continual signal, the radar is locked-onto the target, following it throughout the missile's flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In older radar systems, through the 1980s, lock-on was normally assisted by a change in the radar signal characteristics, often by increasing the pulse repetition frequency. This led to the introduction of radar warning receivers that would notice this change and provide an audible warning to the operator, typically the pilot. Missile lock-on is typically indicated to the pilot or missile operator via an audible tone, a head-up display or a helmet-mounted display.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:23:03.277" LastActivityDate="2015-06-17T12:23:03.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15944" PostTypeId="4" CreationDate="2015-06-17T06:45:39.910" Score="0" Body="Lock-on is a feature of many radar systems that allows it to automatically follow a selected target. Lock-on was first designed for the AI Mk. IX radar in the UK, but first used extensively by US ground-based SCR-584 radar. The SCR-584 demonstrated the ability to easily track almost any airborne target, from aircraft to artillery shells." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:22:36.573" LastActivityDate="2015-06-17T12:22:36.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15945" PostTypeId="5" CreationDate="2015-06-17T06:46:40.567" Score="0" Body="&lt;p&gt;Military aviation is the use of military aircraft and other flying machines for the purposes of conducting or enabling aerial warfare, including national airlift (air cargo) capacity to provide logistical supply to forces stationed in a theater or along a front. Airpower includes the national means of conducting such warfare, including the intersection of transport and war craft. The wide variety of military aircraft includes bombers, fighters, transports, trainer aircraft, and reconnaissance aircraft. These varied types of aircraft allow for the completion of a wide variety of military objectives.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T13:09:01.967" LastActivityDate="2015-06-23T13:09:01.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15946" PostTypeId="4" CreationDate="2015-06-17T06:46:40.567" Score="0" Body="Military aviation (Defense Aviation) is the use of military aircraft and other flying machines for the purposes of conducting or enabling aerial warfare, including national airlift (air cargo) capacity to provide logistical supply to forces stationed in a theater or along a front. " OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:57:48.830" LastActivityDate="2015-06-17T12:57:48.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15947" PostTypeId="1" AcceptedAnswerId="15953" CreationDate="2015-06-17T07:15:31.463" Score="2" ViewCount="440" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/SpaceShipOne&quot; rel=&quot;nofollow&quot;&gt;SpaceShipOne&lt;/a&gt; did not use any wind tunnel testing. According to the &lt;a href=&quot;http://www.scaled.com/projects/tierone/faq&quot; rel=&quot;nofollow&quot;&gt;Scaled Composites FAQs&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Q: Did you do wind tunnel testing?&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;A:&lt;/strong&gt; No. All design refinements and performance predictions have been derived from Computational Fluid Dynamic tools.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What problems would such an aircraft face (which is designed completely without wind tunnel testing)?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="609" LastEditDate="2016-04-26T12:05:02.203" LastActivityDate="2016-04-26T12:05:02.203" Title="What problems can be encountered if an airplane does not undergo wind tunnel testing?" Tags="&lt;aircraft-design&gt;&lt;wind-tunnel&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15948" PostTypeId="5" CreationDate="2015-06-17T07:16:18.073" Score="0" Body="&lt;p&gt;A spacecraft is a vehicle, or machine designed to fly in outer space. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a sub-orbital spaceflight, a spacecraft enters space and then returns to the surface, without having gone into an orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, while those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites. Only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are currently on trajectories that leave our Solar System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orbital spacecraft may be recoverable or not. By method of reentry to Earth they may be divided in non-winged space capsules and winged spaceplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, humanity has achieved space flight but only twenty-four nations actually have spacefaring technology: Russia (Roscosmos, the Russian Space Forces), the United States (NASA, the US Air Force, and several commercial aerospace companies), the member states of the European Space Agency, the People's Republic of China (China National Space Administration), Japan (Japan Aerospace Exploration Agency), and India (Indian Space Research Organisation).&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T12:22:57.853" LastActivityDate="2015-06-17T12:22:57.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15949" PostTypeId="4" CreationDate="2015-06-17T07:16:18.073" Score="0" Body="A spacecraft is a vehicle, or machine designed to fly in outer space. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-17T09:04:39.673" LastActivityDate="2015-06-17T09:04:39.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15950" PostTypeId="2" ParentId="13631" CreationDate="2015-06-17T07:26:38.057" Score="3" Body="&lt;p&gt;In the UK, like the other countries mentioned, you're not required to tell a doctor you're a pilot. However, if you have a medical problem that may impede your ability to fly, you are required to tell the CAA (the national aviation body), who will probably suspend your medical certificate until you get checked out by your medical examiner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been advised by more senior pilots that you &lt;em&gt;shouldn't&lt;/em&gt; tell doctors you're a pilot if you can avoid it. Doctors who don't normally deal with pilots are unlikely to know the criteria for a medical certificate, so may overreact to minor ailments. They might not even know that you get checked out by another doctor anyway! One colleague reported that when his doctor treated him for high blood pressure (that was still within the acceptable limit for his class 2 certificate), she got very agitated when he told her he was a pilot. She thought he shouldn't be allowed to fly with high blood pressure, and was worried that she might be required to tell someone or face legal consequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even so, it might be necessary to tell your doctor for practical reasons. For example, some medications are not allowed for pilots, so you may need to explain to your doctor that they can only prescribe certain drugs or treatments for your condition, which will necessarily involve telling them you're a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although I don't know about the rest of Europe, I would expect it's one of the things that is harmonised across the EASA region.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-06-17T07:26:38.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15951" PostTypeId="2" ParentId="15933" CreationDate="2015-06-17T07:27:20.687" Score="6" Body="&lt;p&gt;Usually by releasing it from a high altitude or at a high speed.  Either one allows some time for the aircraft to depart the immediate vicinity prior to detonation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weapon itself can have some control.  It can have parachutes that increase the time to reach the target or slow it down, or the weapon can have a time delay even after reaching the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides having altitude or speed, the airplane can also &lt;a href=&quot;https://en.wikipedia.org/wiki/Toss_bombing&quot;&gt;toss&lt;/a&gt; the weapon in a way that gives additional separation. &lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-06-17T07:27:20.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15952" PostTypeId="2" ParentId="15933" CreationDate="2015-06-17T07:36:34.223" Score="4" Body="&lt;p&gt;There have been cases of aircraft being damaged when dropping nuclear weapons during testing, but AFAIK none have been destroyed as a result.&lt;br/&gt;&#xA;And those incidents were most likely caused by a test device having a higher than anticipated yield, thus causing the blast effects to have a longer than expected range.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;None of the aircraft involved in the Hiroshima and Nagasaki bombings were damaged as a result, nor was it common during testing.&lt;br/&gt;&#xA;Even the aircraft involved in the biggest nuclear test ever, the 50MT czar bomba dropped by the Soviets over Nova Zembla, was not damaged (or not seriously) as a result. &lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Dropping as far away from the intended point of destination is a good way to limit exposure to both radiation and blast, standoff launching by over the shoulder drops or rocket assisted bombs or missiles can allow launching from even greater distances and/or launching from behind terrain featues (like hills), thus actively shielding the launching aircraft.&lt;br/&gt;&#xA;And the launching aircraft can ensure they place the smallest possible cross section to the point of detonation (iow, turn sharply away from the target zone).&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-06-17T07:36:34.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15953" PostTypeId="2" ParentId="15947" CreationDate="2015-06-17T07:37:47.307" Score="5" Body="&lt;p&gt;For decades, there was no wind tunnel testing performed. There will be, of course, more unknowns about performance and flight characteristics, but with modern computer simulation technology those can be greatly reduced.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="65" LastEditDate="2015-06-17T15:02:29.467" LastActivityDate="2015-06-17T15:02:29.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15954" PostTypeId="1" AcceptedAnswerId="27317" CreationDate="2015-06-17T07:40:08.270" Score="7" ViewCount="737" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/15782/998&quot;&gt;this answer&lt;/a&gt; to a question about controls, Peter Kämpf mentions the Klemm 35:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the rudder has two narrow strips which are deflected slightly to the left and the right, respectively. This increases the force gradient over deflection for the first few degrees when the rudder is moved away from its centered position.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does this interact with left-turning tendency coming from the engine slipstream? Normally, small movements of the rudder are needed to counteract the effect of the slipstream on the fin, so increasing the force required for small movements would seem to hinder rather than help the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, I'd expect the right-pointing strip to be in the lee of the fin (as the slipstream passes left-to-right over it), which would reduce the force on it, letting the rudder move a little to the right on its own, which is exactly what you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What actually happens? Does the neutral position of the rudder change at different power settings when flying straight and level? Does this arrangement reduce your foot workload compared to other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-02T16:22:45.017" Title="How does a self-centering rudder affect left-turning tendency?" Tags="&lt;aircraft-design&gt;&lt;rudder&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15955" PostTypeId="1" AcceptedAnswerId="15957" CreationDate="2015-06-17T10:10:40.220" Score="11" ViewCount="4430" Body="&lt;p&gt;When a big jet like B787 needs to be fueled with empty tanks, ideally how much time it will take to go full?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="8547" LastEditDate="2015-06-17T10:25:23.477" LastActivityDate="2019-05-03T14:57:44.513" Title="How much time it will take a B787 to fuel completely when empty?" Tags="&lt;fuel&gt;&lt;boeing-787&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15956" PostTypeId="1" CreationDate="2015-06-17T10:16:42.123" Score="12" ViewCount="603" Body="&lt;p&gt;As said in the title: where do the names &quot;First&quot;, &quot;Business&quot; and &quot;Economy&quot; class originate from? Why they didn't use the names &quot;First&quot;, &quot;Second&quot; and &quot;Third&quot;. After all it can be hard for someone not that familiar with English to find out that &quot;Business&quot; is ranked higher than &quot;Economy&quot;.&lt;/p&gt;&#xA;" OwnerUserId="8923" LastEditorUserId="19" LastEditDate="2017-11-06T14:53:50.890" LastActivityDate="2017-11-06T14:53:50.890" Title="Where do the names &quot;First&quot;, &quot;Business&quot; and &quot;Economy&quot; class originate from?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="16" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15957" PostTypeId="2" ParentId="15955" CreationDate="2015-06-17T10:19:28.873" Score="14" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/7474sec5.pdf&quot;&gt;Boeing&lt;/a&gt; (via &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/335483/&quot;&gt;airliners.net&lt;/a&gt;), it takes 53 minutes to load 55,800 US gallons with two fuel trucks operating at 35 psi delivery pressure. The total fuel capacity of the 787-8 is 33,340 US gal, so fueling from empty to full should take about 31.6 minutes with two trucks.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="5517" LastEditDate="2015-06-17T13:32:45.797" LastActivityDate="2015-06-17T13:32:45.797" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15958" PostTypeId="1" CreationDate="2015-06-17T10:37:49.440" Score="7" ViewCount="9710" Body="&lt;p&gt;As per ICAO or FAA, what are the minimum radio and navigation equipment must be fitted in VFR and IFR certified aircraft and helicopters? &lt;/p&gt;&#xA;" OwnerUserId="8924" LastEditorUserId="62" LastEditDate="2015-06-17T12:24:35.687" LastActivityDate="2015-06-17T16:21:46.103" Title="What is the minimum radio and navigation equipment for required for VFR and IFR certified aircraft?" Tags="&lt;faa-regulations&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15959" PostTypeId="2" ParentId="15933" CreationDate="2015-06-17T10:54:23.610" Score="29" Body="&lt;h1&gt;Mostly, no.&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The number one factor protecting the aircraft from the effects of the explosion is distance. The aircraft is traveling at a sufficient speed to be very, very far away from the bomb before it detonates. All effects of the explosion can be multiplied by the fraction: 1 / r, where r is the distance between the bomb and the bomber at donation (because circumference is directly proportional to radius). While the effects may be great at the target, they spread out as the circle grows.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Detailed Analysis:&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;As you emphasize the speed of light of radiation from nuclear reactions, I would like to write something about radiation and how it could influence the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Radioactivity&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Nuclear radiation consists of gamma rays, which are some sort of EM waves and particles like helium nuclei (alpha), electrons (beta) and neutrons (without Greek letter...). There is also some more stuff like positrons, protons or heavier fragments of the nuclei, but they behave similarly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The particles indeed escape with a large fraction of the speed of light, but this has nothing to do with the nuke. They will escape with the same speed from a nuclear reactor or from tiny probes in a lab. The nuke just spills more particles than the probe, but does not give them more speed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Alpha &amp;amp; beta radiation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You may know you can stop alpha particles by a piece of paper and beta particles by a 3mm sheet of aluminium. In air (ground, room temperature), alpha particles can travel not more than 10cm, and electrons not more than 10m. The exact range depends on the energy of the particles, but these are the maximum ranges for nuclear reactions. Also, the distances depend on the density of the air, so they travel farther in hot air / at high altitude.&#xA;In general, there is a high electric field inside atoms, and the charged particles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, these two particle types will never reach the aircraft throwing the bomb. Even if they could, they would be stuck in the hull and not do any damage.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Neutrons&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;While alphas and electrons are absorbed on a short range because their charge interacts with the strong fields inside the atoms they are traveling through, neutrons are neutral (really!), which makes them very special. They like to travel through heavy materials like lead, but are easily stopped by plastic or water (one reason for that large swimming pools in nuclear power plants, though swimming usually is prohibited). The reason is that neutrons are like ping pong balls, and lead atoms like basketballs. The basketball will not notice when it's hit by the ping pong ball, while the ping pong ball flies ahead with the same velocity, but different direction. The next hit(s) with other basketballs may put the ping pong ball into its original direction, still with the same speed.&lt;br&gt;&#xA;Hydrogen on the other side is a atom as light as the neutron, hence it's like resting ping pong balls. When hit by the neutron, a hydrogen atom is punched back and absorbs a large fraction of the neutrons energy, causing it to slow down. If the hydrogen atom is bound in a molecule, it may be separated from it during this process. That's why plastic is a good shielding material, but nitrogen and oxygen in the air are already too heavy atoms, so air is a bad shielding material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The metal the aircraft is made of is (nearly) not affected by neutrons. Unfortunately, almost every molecule of the human body contains hydrogen, especially the DNA. While the pilots do not suffer imminent injuries from radiation, this may increase the chance to get cancer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Paul Tibbets, pilot of the Enola Gay (Hiroshima bomb) died in the age of 92.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One fact: &quot;Neutron bombs&quot; are nukes optimized to release a gigantic amount of neutrons. When ignited at high altitude, it kills all animals and humans, leaving the infrastructure (and almost all plants) intact. It's good that they are proscribed by all nations.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Gamma radiation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Coming to gamma radiation. People are most afraid of it, as it penetrates anything, and you know, the Hulk was created by it. Its nature is that all the photons it's made of have a tiny chance to interact with the atoms they are passing by. A few photons are stopped, the rest go ahead. This is why each centimeter of material reduces the intensity by a certain factor, but you will never shield gamma range completely (mathematically). Typical gamma rays need some 10cm of aluminium to reduce the intensity to 50%, or less than 10cm of lead. So, it will pass the aircraft's hull and also the pilots. Again, it will not influence the aircraft. And because it only reacts here and there with matter, there is a high chance the pilot's body will repair the damages, and the pilot will not turn green.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Other effects&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Shock wave&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As said in the other answers, the explosion causes a big shock wave which will definitely shatter and possibly damage the aircraft. &lt;a href=&quot;https://en.wikipedia.org/wiki/Tsar_Bomba&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia says about the Tsar bomb&lt;/a&gt; that it was released from about 10km altitude and detonated at 4km. Using a parachute, the bomb was slowed down allowing the aircraft to travel 45km after release. Yet, the aircraft fell about 1km when it was overtaken by the shock wave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: The shock wave travels at the speed of sound, so the faster the aircraft, the farther away it is when it's overtaken by the shock wave, and the lower the intensity is. (And there are supersonic aircrafts... However, the Tsar shock wave traveled around the earth three times)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Heat&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A nuclear bomb releases a lot of heat. It is said that in Hiroshima, trees 10km away from the explosion caught fire. But the aircraft was farther away and its hull is not only well cooled, but also much less inflammable than a dry tree in the summer. Nevertheless, the &quot;Tsar-bomber&quot; was painted with a special heat-reflecting paint according to the Wikipedia article.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;EMP&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Each nuclear bomb also releases a electromagnetic pulse, which can damage wide electric circuits like power grids as well as any semiconductors. However, the hull of an aircraft already provides some protection against this, and the protection can be improved more to make the aircraft EMP-hard. While today's bombers should be immune to EMP due to these protections, I guess the ones which actually have thrown a nuke were immune as they didn't use any semiconductors.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Summary&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It turns out that radioactivity is not an issue because not all parts have the range to reach the aircraft, and those which do, have no influence on the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The highest thread comes from the shock wave, which definitely damage the aircraft or at least bring it into an odd situation. I don't know what an issue heat is, but the Tsar bomber had some heat reflective painting, and an aircraft usually has a good cooling by its environment. EMP is not an issue as military aircrafts are usually already protected against them.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Remarks&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Of course, radiation damage / effects depend on the time something was exposed to radiation as well as the intensity. So, when I wrote gamma rays will not harm the pilot that much, this already includes a larger distance and thus lower intensity. Near the detonation, the gamma radiation alone would kill you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being exposed to radiation does not automatically make an object radioactive itself. Gamma rays do not make anything radioactive, they ionize atoms and may destroy molecules. The particles may be captured by atoms forming new isotopes / elements. This isotopes / elements may be stable, or may not. If not, that atom is radioactive. However, for most materials, this &lt;em&gt;induced radioactivity&lt;/em&gt; has a short decay time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As said, alpha particles are not an issue as shielding against them is easy, they even can not penetrate the skin. Harmless? Body cells are most vulnerable to radiation damage during their separation, and your guts are covered with mucous membrane, where this happens very frequently. Swallow a piece of alpha emitting material, and getting cancer is more likely than just possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You see, radiation is a vast topic, and what I wrote about aircrafts and pilots may be correct for them, but not in general. Their main protection is: Distance is the best shielding, the farther away, the better.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Hmmm, this answer got a bit longish... sorry for that.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="8837" LastEditDate="2015-06-18T13:17:33.357" LastActivityDate="2015-06-18T13:17:33.357" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="15960" PostTypeId="2" ParentId="11297" CreationDate="2015-06-17T11:08:44.757" Score="3" Body="&lt;p&gt;SMAs are being used by Boeing in so called chevrons, See this &lt;a href=&quot;http://www.boeing.com/news/frontiers/archive/2006/march/i_tt.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;link&lt;/a&gt; and this image:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ShlGv.jpg&quot; alt=&quot;Chevrons&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is that these chevrons heat up due to the hot flow coming from the engine. This causes them to deform, and bend into the oncoming flow.&#xA;This causes vortices, which will reduce the engine noise by gradually mixing the hot and cold flows coming from the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that this is a very different application than the one OP mentioned, as it is non-critical and not a stress bearing part, however, it does show that SMA's can be used in commerical aircraft &lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-06-17T13:56:23.143" LastActivityDate="2015-06-17T13:56:23.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15962" PostTypeId="1" AcceptedAnswerId="15984" CreationDate="2015-06-17T12:06:28.943" Score="7" ViewCount="550" Body="&lt;p&gt;The term &quot;&lt;strong&gt;Memorandum of Understanding&lt;/strong&gt;&quot; often pops up when airlines are about to order aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a little confused as of the importance it carries:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does it contain any details if the agreement is broken?&lt;/li&gt;&#xA;&lt;li&gt;Does it state when and where aircraft will be ordered? Or is it just &quot;&lt;em&gt;we will order from you&lt;/em&gt;&quot;?&lt;/li&gt;&#xA;&lt;li&gt;Does it contain any details on any discounts/benefits or similar? I imagine these would in some form be put down on paper before starting negotiations with which company to order from.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-17T12:14:11.523" LastActivityDate="2015-06-17T20:21:16.070" Title="What are the implications of a Memorandum of Understanding during an aircraft order process?" Tags="&lt;aircraft-order&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15963" PostTypeId="2" ParentId="15823" CreationDate="2015-06-17T12:17:08.013" Score="1" Body="&lt;p&gt;I'd say radiation from a chest X-ray is 0.013 mSv. Background radiation is said 2-3 mSv per year. If you live in a place with granitic soil, you get around 2.5 mSv a year. Individuals exposed to 6 mSv a year or more should be monitored. Work Exposure is restricted to 20 mSv annually for a period of 5 years, with a maximum of 50 mSv in any one year. An abdominal CT means 10 mSv, so, background average radiation an US person receives a year is considered to have doubled, and this means a very small, but mensurable increase in the risk for Leukemia and Lymphoma (e.g. INWORKS study, K Leuraud et al). Some elements used in construction released radioactive gases as Radon. Radon was found in too high concentrations inside some rooms in certain houses. High Radon concentration exist in Uranium mines, however, the type of radiation matters, and also the pace of radiation exposure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extremely energetic Cosmic rays are blocked by atmosphere, but not by an airplane's hull. Also UV radiation is higher in the heights. This induces that flight crews do have a higher incidence of all types of skin cancer, including malignant Melanoma, and also male crew members do tend having more girls than boys in their offspring. &#xA;Perhaps the reason for this shift in sex ratio is that the redundant X chromosome in girls compensates for the damages that the other X chromosome may suffer. Boys have only one X chromosome. If other chromosomes from the male parent are damaged, it may result in a higher incidence of miscarriages, even unnoticed ones, in the pregnancies resulting from males working in airplane crews.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data about Radiation and UV Light as a carcinogen can be found at several cancer organizations sites, as the American Cancer Society, specially in their publication: 'CA, a cancer journal for clinicians', that is of open access. (eg Linet et al, 2012; Kim 2009; Hunter 2005; Heath 1996; Weinstein 1982; Joanna F Haas, 1979; Ryser 1974; Simpson 1958)&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-07-02T16:12:02.100" LastActivityDate="2015-07-02T16:12:02.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15965" PostTypeId="2" ParentId="15958" CreationDate="2015-06-17T12:51:40.530" Score="7" Body="&lt;p&gt;In the US, this in in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1205&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.205&lt;/a&gt;, &lt;em&gt;Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a lot of detail so you can check the whole thing, but looking only at communication and navigation items, the required equipment is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VFR (including night VFR)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Magentic direction indicator&lt;/li&gt;&#xA;&lt;li&gt;Altimeter (for airspace navigation)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;IFR&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Instruments and equipment as for VFR&lt;/li&gt;&#xA;&lt;li&gt;Two-way radio communication and navigation equipment suitable for the route to be flown&lt;/li&gt;&#xA;&lt;li&gt;Rate of turn indicator (for timed turns)&lt;/li&gt;&#xA;&lt;li&gt;Directional gyro&lt;/li&gt;&#xA;&lt;li&gt;A clock (&lt;a href=&quot;https://aviation.stackexchange.com/q/9695/62&quot;&gt;this question&lt;/a&gt; explains why a clock is needed for IFR navigation)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That list might seem very short, but remember that under VFR there's no requirement to have radios and there are even some vintage aircraft flying around with no electrical system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under IFR it's fairly obvious that you need a radio for ATC communication and whatever navigation equipment is needed for your planned flight, e.g. you can't fly a GPS approach unless you have an IFR-certified GPS. But there are multiple approach types and they all have different equipment requirements so the regulations just give a general statement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that commercial flights operating under parts 135 or 121 will have additional requirements; the information above is really the bare minimum that's legally possible for GA flights.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-06-17T16:21:46.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15966" PostTypeId="2" ParentId="15942" CreationDate="2015-06-17T13:36:30.597" Score="11" Body="&lt;p&gt;Short Answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will be very generic... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on what type of missile it is: either IR or radar-guided.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With IR missiles, the missile is caged and locked at missile boresight.  The missile is commanded to the aircraft cueing system.  When the target enters the missile's FOV, the pilot uncages the seeker head, at this point you will hear a loud, &quot;whiney&quot; audible tone.   The missile then transfers to track mode.  The pilot pickles... the missile batteries become operational, fins are unlocked, autopilot takes over, midbody connector is retracted, then ignition is commanded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With radar-guided missiles, it depends on the missile and what type of radar they have.  Usually the radar is slewed to a target and locked up.  When the pilot pickles, the missiles is either receiving data from the aircraft via datalink or is in active mode with the missile's radar tracking the target.  Eventually the missile's radar will take over and track the target.  The datalink can be terminated early by the pilot if the missile's radar can take over allowing for some pretty cool tactical stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer:&#xA;There is A LOT more to it, but this is very basic.  Tread very lightly with questions like this.  A lot of the stuff (especially numbers) with regards to weaponry and modern threats are classified.  And even though some of the stuff isn't classified, it's still OPSEC and shouldn't really be discussed on an internet forum. &lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastActivityDate="2015-06-17T13:36:30.597" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15967" PostTypeId="1" CreationDate="2015-06-17T13:45:19.650" Score="7" ViewCount="876" Body="&lt;p&gt;I think in general there is less than 10% humidity is being maintained in most of the commercial aircraft but I think they have improved that in the 787. I am not sure how much that is and if the cabin and cockpit have same amount of that?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-06-17T15:41:02.340" LastActivityDate="2015-06-17T15:50:58.730" Title="How much humidity is being maintained in cabin and cockpit of B787?" Tags="&lt;boeing-787&gt;&lt;humidity&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15968" PostTypeId="1" CreationDate="2015-06-17T14:07:46.853" Score="4" ViewCount="232" Body="&lt;p&gt;Do anti-collision lights installed in aircraft lose their intensity over time and need to be replaced every few hundred hours of operation?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="14897" LastEditDate="2019-04-06T11:55:26.753" LastActivityDate="2019-04-06T11:55:26.753" Title="Do anti-collision lights in aircraft lose intensity over time?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-external-lights&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15969" PostTypeId="1" AcceptedAnswerId="15972" CreationDate="2015-06-17T14:21:51.553" Score="10" ViewCount="2185" Body="&lt;p&gt;As per this picture of the Embraer 190, but also on other Aircraft, the Control column stick has a very awkward position for hands. Why is this design chosen? To me it seems that the position of the hands would be really uncomfortable as the pilots hands would be tilted at 45 degrees and not stay vertical, thus putting a lot of stress on them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/yyQBo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2016-07-04T11:19:35.427" LastActivityDate="2020-07-08T14:51:52.287" Title="What is the rationale behind the Embraer 190's control column design?" Tags="&lt;flight-controls&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15970" PostTypeId="2" ParentId="15968" CreationDate="2015-06-17T14:31:54.610" Score="5" Body="&lt;p&gt;No, however the intensity is a feature of the bulb rather than the purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, incandescent bulbs were used, followed by Xenon flashtubes. Currently, LEDs are used in &lt;a href=&quot;https://en.wikipedia.org/wiki/Anti-collision_light&quot; rel=&quot;noreferrer&quot;&gt;anti-collision lights&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Navigation_light&quot; rel=&quot;noreferrer&quot;&gt;other lights&lt;/a&gt; on aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note that there are some requirements needed for bulbs used. They are mentioned in &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.1399&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 25.1399&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Show a white light for at least 2 nautical miles at night under clear&#xA;  atmospheric conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-17T14:31:54.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15971" PostTypeId="2" ParentId="11297" CreationDate="2015-06-17T14:39:45.957" Score="0" Body="&lt;p&gt;Im not sure this falls under Smart materials but is an interesting side note about shape distortion with heat. The SR-71 stealth plane was subject to such high heat at upper ends of its speed range that the planes panels were actually &lt;a href=&quot;http://physicsbuzz.physicscentral.com/2011/02/betrayed-by-heat-sr-71-blackbird.html&quot; rel=&quot;nofollow&quot;&gt;designed with gaps&lt;/a&gt; so that it would not crunch its self to bits when it heated up and expanded. Keeping this in mind you can get an idea of how fast you need to travel to generate enough surface heat to deform the metal substantially (im sure its a bit slower for softer metals).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to the topic at hand  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weight&lt;/strong&gt; is a serious concern as well. Generating heat or substantially cooling a structure at will is no simple task. Such systems would further weigh down an airplane when weight is really the biggest concern in aviation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Money&lt;/strong&gt; and well more money is a very real factor in airplane building. FAA type certs are not cheap or easy to come buy and as such commercial aviation tech tends to lag behind what is hot on the market since it takes many years to get an airplane designed, certified and into production. People have been building aluminum airplanes since we had engines powerful enough to make it a reality. Its a light, fairly easy to work with material that has been tried and tested on thousands of airframes flown for millions of hours. We have tooling and shops to make it into what ever we may need. Keep in mind that introducing a new material is not simple. If you would like a current example look at the adoption of &lt;a href=&quot;https://en.wikipedia.org/wiki/Carbon_(fiber)&quot; rel=&quot;nofollow&quot;&gt;carbon fiber&lt;/a&gt; which has also been around for some time now and is only &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;just beginning to see use in real commercial aviation&lt;/a&gt; on a large scale. Its been used in general aviation for a bit longer since the parts are smaller and a bit simpler to lay up but still more costly than aluminum.         &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-17T14:45:14.210" LastActivityDate="2015-06-17T14:45:14.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15972" PostTypeId="2" ParentId="15969" CreationDate="2015-06-17T15:08:18.173" Score="10" Body="&lt;p&gt;I think it's quite similar to a steering wheel with your hands a bit to the upper half. You rest your hands onto the yoke with this variant, as compared to the other ones where they are vertical and inclined to slide downwards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I'm certainly not sure, it could be a sensory thing as well, perhaps allowing better feel for the position as you are putting less energy into your arm and tiring it out less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it's a minor design detail and had it been uncomfortable/ problematic they would have got rid of it pretty quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=MHRqeR787jA&quot; rel=&quot;noreferrer&quot;&gt;Embraer Angled Yoke&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=UqCVx3giUBE&quot; rel=&quot;noreferrer&quot;&gt;Bombadier Vertical Yoke&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-18T12:50:06.903" LastActivityDate="2015-06-18T12:50:06.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15973" PostTypeId="1" AcceptedAnswerId="15975" CreationDate="2015-06-17T15:22:52.243" Score="3" ViewCount="337" Body="&lt;p&gt;Instead of &lt;a href=&quot;https://en.wikipedia.org/wiki/Thames_Estuary_Airport#Maplin_.28Foulness.29&quot; rel=&quot;nofollow&quot;&gt;Thames Estuary Airport&lt;/a&gt; from Maplin in 70s to the latest inner Thames Estuary Airport, is there any proposal airport(s) raised after WWII but cancel/rejected eventually?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there is a airport proposal in the north-west London but it is cancelled eventually. Does anyone know about this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In stead of these two, is there any other airport proposals?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="19" LastEditDate="2016-07-04T11:20:57.740" LastActivityDate="2016-07-04T11:20:57.740" Title="What airport proposal(s) has London seen after WWII?" Tags="&lt;airport&gt;&lt;aviation-history&gt;&lt;airport-design&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15974" PostTypeId="2" ParentId="15967" CreationDate="2015-06-17T15:40:21.783" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.reuters.com/article/2013/07/20/us-boeing-dreamliner-investigation-idUSBRE96I18020130720&quot;&gt;These&lt;/a&gt; &lt;a href=&quot;http://blogs.wsj.com/middleseat/2012/02/16/787-dreamliner-improvement-is-more-incremental-than-revolution-in-flying/&quot;&gt;sources&lt;/a&gt; say that most airliners maintain a humidity of 4-7%, while the 787 maintains 10-15%. Of course these values can vary with conditions, and other sources put them &lt;a href=&quot;http://www.airlineratings.com/news/311/787-banishes-jetlag-believe-it&quot;&gt;lower&lt;/a&gt; or &lt;a href=&quot;http://www.askthepilot.com/questionanswers/cabin-air-quality/&quot;&gt;higher&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin and cockpit will not have very different air qualities. While some cockpits may humidify the cockpit air slightly, the cockpit tends to have a &lt;a href=&quot;https://books.google.com/books?id=ydjOVFSW8AoC&amp;amp;lpg=PA52&amp;amp;dq=cockpit%20humidity&amp;amp;pg=PA52#v=onepage&quot;&gt;greater amount of circulation&lt;/a&gt;, leading to drier air than the rest of the cabin.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-06-17T15:50:58.730" LastActivityDate="2015-06-17T15:50:58.730" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15975" PostTypeId="2" ParentId="15973" CreationDate="2015-06-17T16:48:56.893" Score="4" Body="&lt;p&gt;There was one more proposal before Thames Estuary Airport. That was the Cublington airport, which was rejected by planner &lt;a href=&quot;https://en.wikipedia.org/wiki/Colin_Buchanan_(town_planner)&quot; rel=&quot;nofollow&quot;&gt;Colin Buchanan&lt;/a&gt;,as &quot;an environmental disaster.&quot; Later the government rejected the proposal of this airport, and rather went for Thames Estuary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than that, there are no more proposals for new airports, but there are certain plans for expanding existing Heathrow and Gatwick. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Airports Commission says there is a need for one additional runway in the South East of England by 2030.&#xA;It has shortlisted three options:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A third runway at Heathrow&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Lengthening an existing runway at Heathrow&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A second runway at Gatwick&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Read in detail about all of them &lt;a href=&quot;http://www.bbc.com/news/uk-19570653&quot; rel=&quot;nofollow&quot;&gt;HERE&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-18T06:08:12.753" LastActivityDate="2015-06-18T06:08:12.753" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15976" PostTypeId="2" ParentId="7916" CreationDate="2015-06-17T18:28:38.127" Score="3" Body="&lt;p&gt;I am on a U.S. Air flight right now.  Pretty sure that the plane is an A330.  About 20 minutes after take-off, the pilot said that he had to lower the landing gear to cool off the brakes.  After about 3 minutes of much noise, and some chop, he raised them and said that it had worked.&lt;/p&gt;&#xA;" OwnerUserId="8933" LastEditorUserId="19" LastEditDate="2015-06-17T21:31:51.897" LastActivityDate="2015-06-17T21:31:51.897" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15977" PostTypeId="2" ParentId="13042" CreationDate="2015-06-17T18:32:09.587" Score="9" Body="&lt;p&gt;Apologies if this is tangential but other properties of kerosene (aka kerosine) as turbine fuel were brought up.  To my knowledge, all &quot;Jet fuels&quot; (intended for aircraft use) are based on kerosene.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another property of jet fuel that was not mentioned is freeze point where viscosity drops because of wax formation and pumps and filters begin to clog.  Ordinary kerosene (as used in lanterns and space heaters) rarely has to deal with sub-zero temperature (e.g. -40C) and 30,000 feet altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also important is volatility which can be reduced at low temperatures and impede combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;see &lt;a href=&quot;http://www.shell.com/global/products-services/solutions-for-businesses/aviation/shell-aviation-fuels/fuels/types/civil-jet-fuel-grades.html&quot;&gt;http://www.shell.com/global/products-services/solutions-for-businesses/aviation/shell-aviation-fuels/fuels/types/civil-jet-fuel-grades.html&lt;/a&gt; for different fuels and their freeze points.&lt;/p&gt;&#xA;" OwnerUserId="8932" LastEditorUserId="8932" LastEditDate="2015-06-17T18:38:49.773" LastActivityDate="2015-06-17T18:38:49.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15978" PostTypeId="2" ParentId="15926" CreationDate="2015-06-17T18:32:39.033" Score="24" Body="&lt;p&gt;Evolution has created this wonderful thing called &lt;em&gt;stress&lt;/em&gt;. We tend to think of stress as something negative that is to be avoided, and that is certainly true: &lt;em&gt;prolonged&lt;/em&gt; periods of stress will do all sorts of damage to your body and mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for &lt;em&gt;short&lt;/em&gt; periods of time, stress is a wonderful invention that lets us survive situations we otherwise wouldn't: when we come under stress, when that sabre-tooth tiger pops out from behind the bushes, our autonomous systems produce anti-inflammatory agents, dampen our pain reception, flood our system with performance enhancing drugs, improve our perception, shorten our reflexes, increase our energy levels … and, yes, also repress our sneeze and cough reflexes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you ever had the experience that, after a long period of stress, just when you were finally looking forward to some well-deserved vacation, you get sick at the most inopportune time, right at the beginning of your vacation? Well, actually, you didn't get sick, you were sick all along, but during the stress period, your body suppressed the symptoms, and as soon as the stress goes away, the illness, wich may have been brewing for days or even weeks, breaks out in full.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to answer your question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What if a aerobatic fighter pilot sneezes in middle of a maneuver?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He doesn't. Stress will prevent him from doing so.&lt;/p&gt;&#xA;" OwnerUserId="3721" LastActivityDate="2015-06-17T18:32:39.033" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15980" PostTypeId="2" ParentId="15813" CreationDate="2015-06-17T20:17:41.510" Score="1" Body="&lt;p&gt;Biplanes and ultra-lights don't have any doors at all. In general, for any plane the wing, the empennage and, to a lesser extent, the surface area on the lower part of the fuselage is all that is important. If you installed structure-reinforcing crossbars you could remove the entire fuselage wall of a commercial jet and it would still fly.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-17T20:17:41.510" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="15981" PostTypeId="1" AcceptedAnswerId="15992" CreationDate="2015-06-17T20:18:13.500" Score="10" ViewCount="910" Body="&lt;p&gt;I'm considering a trip to Nova Scotia from New York in a Cessna 172 or a Piper Archer. The trip is about 3.5 - 5 hours long and could involve some small open ocean portions. Since Nova Scotia has variable weather, high wind, and is pretty rural, I'm interested in knowing if anyone has any recommendations, warnings, or resources for flying to Nova Scotia or Newfoundland. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know this questions is pretty broad, so I welcome any suggestions for narrowing the scope. I've just had a hard time finding anything on the internet about making a trip to the area.  &lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="4509" LastEditDate="2015-06-18T20:07:51.377" LastActivityDate="2015-06-18T20:07:51.377" Title="Are there special safety considerations when flying to/in Atlantic Canada?" Tags="&lt;general-aviation&gt;&lt;navigation&gt;&lt;flight-planning&gt;&lt;canada&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15982" PostTypeId="5" CreationDate="2015-06-17T20:19:15.900" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-06-17T20:19:15.900" LastActivityDate="2015-06-17T20:19:15.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15983" PostTypeId="4" CreationDate="2015-06-17T20:19:15.900" Score="0" Body="Nova Scotia is a province on the Atlantic coast of the country of Canada" OwnerUserId="4509" LastEditorUserId="4509" LastEditDate="2015-06-17T20:32:04.347" LastActivityDate="2015-06-17T20:32:04.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15984" PostTypeId="2" ParentId="15962" CreationDate="2015-06-17T20:21:16.070" Score="7" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Memorandum_of_understanding&quot;&gt;Memorandum of Understanding&lt;/a&gt; (MOU) isn't an aviation term or practice, it's a general business/legal term for a 'pre-contract' of some kind. Before two companies commit to a legally binding and perhaps very expensive contract, they'll often prepare an MOU to make sure that everyone involved has the same understanding of what will be in the contract. That way, there shouldn't be any big surprises or fundamental disagreements when the real contract is prepared.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the context of aviation, that could be things like how many aircraft will be purchased and when, or what the price is &lt;em&gt;anticipated&lt;/em&gt; to be, or anything else that both side consider important. That means that the information in an MOU could be very interesting for other parties (&quot;can you explain why our competitors are paying you $50m less per aircraft than we do?&quot;), so they're usually confidential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another common use for MOUs is for PR/Marketing purposes. If two companies are discussing a joint business venture they might come up with an MOU and use it to generate market interest or even raise capital (&quot;I know we're a small company but we have an MOU with Boeing to jointly research alternative fuels&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that background, I don't think it's likely that you'll get any specific answers to your questions. An MOU could include all the things you mentioned but only a real contract is enforceable.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-06-17T20:21:16.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15985" PostTypeId="2" ParentId="15981" CreationDate="2015-06-17T20:24:03.220" Score="7" Body="&lt;p&gt;If you are heading out over open water many people will tell you take a twin engine plane. But that may be impractical or not possible if you are not rated to do so. You may want to consider investing in or renting (if you can) an &lt;a href=&quot;http://www.epirb.com/&quot;&gt;EPIRB&lt;/a&gt; if you are worried about the open water section. Some &lt;a href=&quot;http://www.usaboatstore.com/Kent-Sporting-Goods-102000-200-004-12.htm?feed=Froogle&amp;amp;gclid=CjwKEAjwtYSsBRCDx6rM1v_uqmsSJAAZgf2qX-CkifRqbePQQeYIeGLvKmwCB7QY-rHCPJxPjLgEthoCFw7w_wcB&quot;&gt;type II PFDs&lt;/a&gt; are cheap and may provide a piece of mind. Depending on where you are the north atlantic is very cold so ditching is more of a time issue than anything. No need to go crazy with it and useful load may prevent it but you can always get a &lt;a href=&quot;http://www.sportys.com/pilotshop/rescue-raft-four-man-life-raft.html&quot;&gt;life raft.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;- Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As listed &lt;a href=&quot;https://en.wikipedia.org/wiki/Climate_of_Nova_Scotia&quot;&gt;here&lt;/a&gt; the area can see thick fog roll in from the ocean. This will pose 2 issues for you, one is substantial worse than the other. On the safe side you may be stuck on the ground when you need to get the rented plane back. This may be no more than a monetary issue (if they charge you some late fee or something). The far worse case is being stuck in the air and having to divert (potentially far) to land safely under VFR. Keep in mind that even under IFR there are minimums and ground fog may knock out even an instrument approach. Either way it still gives you a solid other option. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should really get to know the emergency procedures for open water ditching and rescue as per my earlier notes as well.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume you will plan a fuel stop somewhere in Maine (right before you turn out over water). That is a leg I would want to tackle with full tanks any way. Keep in mind 3.5-5 hours in an archer or 172 can be a grueling task. There are lots of fatiguing factors here. I would try and get the plane and just fly in your area for 3.5 hours (if you have not already) to make sure you feel comfortable being up for that long. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use anything digital like an iPad etc, backup batteries are a must. I would even being back up paper charts for this journey. GPS could be a life saver too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think customs is some how involved but I have never flown out of the country so I don't know, if you have not you should look into it and make sure there is nothing you need to do ahead of time.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-17T20:35:17.133" LastActivityDate="2015-06-17T20:35:17.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15986" PostTypeId="2" ParentId="15981" CreationDate="2015-06-17T20:36:39.827" Score="5" Body="&lt;p&gt;Make thorough backup plans for any kind of weather problems such as low visibility or high winds. Always have a place to land and stay over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make sure your emergency locator thingy is new and working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a small survival kit which includes matches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make sure you have a backup radio and GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, if I was flying over the Bay of Fundy I would bring a size A or B oxygen tank and fly at 15,000 feet during the middle part. If you do that, you can pretty much stay within gliding distance of land the whole way. (You know the best glide speed of both aircraft, right?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, the neck off St. Mary's Bay looks pretty bad for off-field landings so you definitely want to pick a spot beforehand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...and remember, the engine always runs rougher over water :-)&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-06-17T20:45:52.793" LastActivityDate="2015-06-17T20:45:52.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15987" PostTypeId="2" ParentId="11906" CreationDate="2015-06-17T20:42:48.613" Score="2" Body="&lt;p&gt;Do not mix EGT and ITT. EGT is exhaust gas temperature and ITT is Inter stage temperature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally when starting a PT6 you should watch ITT and depending which PT6 model you use maximum ITT may vary but it`s around 1600 degrees Fahrenheit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I work for Pratt &amp;amp; Whitney and PT6 is probably the best engine ever made in it`s class as someone mentioned. When starting a PT6 the engine will not get close to the maximum allowable ITT unless you have a problem.&#xA;Good engine choice hope you will have good time flying with this engine.&lt;/p&gt;&#xA;" OwnerUserId="8937" LastEditorUserId="19" LastEditDate="2015-06-17T21:54:58.647" LastActivityDate="2015-06-17T21:54:58.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15988" PostTypeId="2" ParentId="7916" CreationDate="2015-06-17T20:46:02.370" Score="9" Body="&lt;p&gt;The reasons I can think of offhand for extending the gear for other than landing are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;As has been mentioned in a previous answer, use of the landing gear as a speed brake. The Fokker F-27 had a speed brake switch on the front panel that when used lowered the main landing gear but left the nose gear retracted. At the two 747 carriers I worked for in the 1990s, we occasionally dropped the gear to get more drag for a steeper descent. As I remember the max gear extension/retraction speed was 270 knots, but once extended the max speed was 320 knots.&lt;/li&gt;&#xA;&lt;li&gt;To cool hot brakes or hot tires. This was the most common reason in my experience for extending the gear. The 747-100/200 was supposed to be taxied at no greater than 25 kts, which meant that braking was needed during taxi even with engines at idle. Tire flexing also produced significant heat. There was a recommendation not to taxi more than 30,000 feet as I remember because of these factors. If you were using, say, the reef runway at Honolulu, you exceeded that distance by the time you lifted off, and if you were above 800,000 lbs you were guaranteed serious heating.&lt;/li&gt;&#xA;&lt;li&gt;To pre-cool the brakes and tires if you had a short leg followed by a quick turn. The 747 was originally designed to stay in the air for awhile before landing. The story I most often heard was they designed for 5.5 hours of cooling in the wheel wells before the gear would be used.&lt;/li&gt;&#xA;&lt;li&gt;To burn extra fuel to get below landing weight. Rare, but it could happen if you were tankering fuel such to arrive at max landing weight and for whatever reason the leg burn was less than planned. Fuel burn increase with the landing gear down is quite dramatic. We were tankering fuel once from Yakota, Japan to Osan, Korea, and we couldn't get the landing gear up. Our choices were to dump fuel and return to Yakota or to proceed to Osan with the gear down. We chose the latter. We couldn't get above 25,000 and our fuel burn was twice normal. Confused the controllers; they kept wondering by we were so slow and so low. We kept having to explain.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-06-17T20:46:02.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15989" PostTypeId="1" AcceptedAnswerId="15990" CreationDate="2015-06-17T21:43:00.853" Score="14" ViewCount="2568" Body="&lt;p&gt;Reading the question found here: &lt;a href=&quot;https://aviation.stackexchange.com/q/7916/3309&quot; title=&quot;Do some aircraft lower the landing gear mid-flight&quot;&gt;Do some aircraft lower the landing gear mid-flight&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the replies got me curious... Do heavy jets or even business jets have brake temp sensors or indicators?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the fast-movers we don't have this luxury and I've never even heard of it until now.  If we suspect hot brakes we just taxi to the hot brakes area and either wait or ground egress if a fire may occur.  We do have wheel speed sensors with anti-skid brakes that use different channels, but nothing that reports to the pilot the brake temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you guys do have this feature, do you have a indicator that shows brake temperature?  Or is there a light that illuminates or even a PFL (pilot fault list) that appears on one of the MFDs?&lt;/p&gt;&#xA;" OwnerDisplayName="user3309" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-06-17T22:36:02.993" Title="Do airliners or business jets have brake temperature sensors?" Tags="&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="15990" PostTypeId="2" ParentId="15989" CreationDate="2015-06-17T22:10:21.293" Score="19" Body="&lt;p&gt;Brake temperature sensors are quite common on airliners. Turnaround times of large aircraft are often impacted by the required cooling time. This is because during take-off the brakes must be cool enough to absorb the heat of a possible rejected take-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/R2xrX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Brake temperature and tire pressure indication on the Airbus A330 (note the deflated tire &amp;amp; high temperatures)&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://karlenepetitt.blogspot.nl/2012/01/a330-automation-and-efficiency.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Karlene Petitt blogspo&lt;/a&gt;t&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-17T22:10:21.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15991" PostTypeId="2" ParentId="15989" CreationDate="2015-06-17T22:16:20.997" Score="12" Body="&lt;p&gt;Boeing 747-100 and -200 aircraft had both brake and wheel well temperature sensors. The sensor data was fed to both gauges and alert lights on the f.e. panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Brake overheat was mostly a landing event. If the brake temps were climbing rapidly, the f.e. would typically alert whomever was taxing to minimize brake usage. If the brake temp went into the red/alert light came on you were supposed to alert ground personnel to stay away from that side of the tires where the thermal plugs were. It was also common practice to request a huffer to cool the brakes as soon as you parked. Freighters were more likely to have brake heating problems than pax aircraft because they tended to land closer to the max landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wheel well overheat was a post takeoff event, caused by tire heating during taxi and takeoff as well as brake use during taxi. There was no temperature gauge, only an overheat light. The checklist action was to lower the landing gear. There were no fire extinguishers in the wheel wells.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-06-17T22:36:02.993" LastActivityDate="2015-06-17T22:36:02.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15992" PostTypeId="2" ParentId="15981" CreationDate="2015-06-18T01:09:04.150" Score="9" Body="&lt;p&gt;Plan for unexpected weather amid limited options for dealing with it.  I've flown a number of times between Newark (EWR) and Halifax NS (YHZ), Moncton NB (YQM), and St Johns, NL (YYT).  It can be quite foggy and windy and in the cold months braking action can become a factor.  A lack of options can be problematic.  When we flew EWR-YHZ we often chose EWR as an alternate and I've turned around as late as talking to Halifax approach as braking action become NIL and we didn't have gas to wait it out.  Going out to YYT we'd only have enough gas to get to Gander (YQX) if we couldn't get a good approach in at St Johns.  I flew a capable jet under IFR with Cat II approach capabilities so your concerns will be slightly different down low and VFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although you are VFR, I'd play by IFR rules as alternates and fuel is concerned.  Plan enroute alternates and carry enough gas to get to your destination and get to your second choice with some gas to spare.  The weather can turn quickly and the fog in any of the maritime airports can be thick enough to turn even IFR GA planes away.  Have a plan to be able to get on the ground somewhere else.  Also consider how fatigue will play into your decision making once you are out there.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-06-18T01:09:04.150" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="15993" PostTypeId="1" AcceptedAnswerId="16003" CreationDate="2015-06-18T04:32:46.787" Score="2" ViewCount="144" Body="&lt;p&gt;I live in Las Vegas, which obviously has a large airport with a broad array of international flights. Is there a quick way for me to see all the non-stop commercial flights that are available to Mexico? I don't need to necessarily know the airline, just which cities are available for non-stops from Las Vegas. &lt;/p&gt;&#xA;" OwnerUserId="3410" LastEditorUserId="3677" LastEditDate="2015-06-18T13:28:57.370" LastActivityDate="2015-06-18T13:37:45.227" Title="How can I see all commercial destinations to a country from a particular airport?" Tags="&lt;flight-schedules&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2015-06-18T21:17:37.760" ContentLicense="CC BY-SA 3.0" />
  <row Id="15994" PostTypeId="2" ParentId="15993" CreationDate="2015-06-18T05:54:19.710" Score="3" Body="&lt;p&gt;Wikipedia entries for airports almost always have the list of destinations served from the airport, and I think the plane-spotter community keeps them very up to date. But it is indexed by airline, not country. Given the likelihood of there being only 2-3 destination airports in a single country, you could search on those city names - or else just browse the list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The entry for McCarran International in Las Vegas is &lt;a href=&quot;https://en.wikipedia.org/wiki/McCarran_International_Airport#Airlines_and_destinations&quot;&gt;https://en.wikipedia.org/wiki/McCarran_International_Airport#Airlines_and_destinations&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="396" LastActivityDate="2015-06-18T05:54:19.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15995" PostTypeId="2" ParentId="15993" CreationDate="2015-06-18T06:24:07.937" Score="3" Body="&lt;p&gt;For seeing all non-stop flights, you may use any travel website. See this example using &lt;a href=&quot;http://www.cleartrip.com/flights/international/results?from=LAX&amp;amp;to=MEX&amp;amp;depart_date=19/06/2015&amp;amp;adults=1&amp;amp;childs=0&amp;amp;infants=0&amp;amp;class=Economy&amp;amp;airline=&amp;amp;carrier=&amp;amp;intl=y&amp;amp;sd=1434607961827&amp;amp;stops=0&amp;amp;tripDuration=2-23&amp;amp;layoverDuration=0-16&quot; rel=&quot;nofollow&quot;&gt;Cleartrip&lt;/a&gt; for non-stop flights between LA and Mexico.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, you can use any flight tracker for all the cities served by an airport. Have the knowledge of airlines and airliner as well! &lt;a href=&quot;https://uk.flightaware.com/live/airport/KLAX/departures/all&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; are all the departures from KLAX by &lt;a href=&quot;http://www.flightaware.com&quot; rel=&quot;nofollow&quot;&gt;Flightaware&lt;/a&gt;. Alternately, you may check for the airport's website to see all the destinations served by an airport (available at websites of only few airports). For ex. &lt;a href=&quot;http://www.edinburghairport.com/flights/destinations-and-airlines&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; are all the destinations served by Edinburgh airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, if these don't work out, go with timbo's idea!&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-06-18T06:24:07.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15996" PostTypeId="2" ParentId="1979" CreationDate="2015-06-18T07:30:59.683" Score="2" Body="&lt;p&gt;To add to the answers above: the other main reason (besides condensation) for keeping humidity low is to prevent the growth of mold and bacteria in the cabin and the air conditioning system, which over time may pose a health hazard to the plane's occupants. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I can't stress enough that the air is &lt;strong&gt;not de-humidified&lt;/strong&gt;, but that the outside air (which is pumped into the fuselage to provide pressure and fresh air) at cruising altitudes is bone-dry. The air in the cabin is actually more humid than it would otherwise be, thanks to the passengers (when they exhale or sweat they release water vapor into the air, and since about 50% of the cabin air is re-used it helps to keep the humidity levels a little higher than they would normally be). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The newest-generation of widebody planes from Boeing and Airbus (787 and A350) actively humidify the air in the cabin, but that requires carrying extra water on every flight (50-100kg, according to &lt;a href=&quot;http://www.flightglobal.com/news/articles/in-focus-manufacturers-aim-for-more-comfortable-cabin-369425/&quot; rel=&quot;nofollow&quot;&gt;Flight Global&lt;/a&gt;, plus the weight of the humidification equipment). Additionally, these airplanes need to install active &lt;strong&gt;drying&lt;/strong&gt; systems in the the areas outside the cabin (e.g. behind the lining or above the cabin ceiling) to prevent the insulation mats from soaking up all that extra humidity (&lt;a href=&quot;http://www.ctt.se/zonal-drying/&quot; rel=&quot;nofollow&quot;&gt;example from CTT&lt;/a&gt;). In conclusion, the air will be more humid on these aircraft, but it takes a lot of effort (and weight). &lt;/p&gt;&#xA;" OwnerUserId="1478" LastActivityDate="2015-06-18T07:30:59.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="15997" PostTypeId="1" CreationDate="2015-06-18T07:34:13.640" Score="12" ViewCount="1523" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=AW7znizsUEw&quot;&gt;This video&lt;/a&gt; details with an example why not to reject takeoff after $V_1$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains an example of a 747 running off the end of the runway, due to a rejected takeoff past $V_1$ prompted by an engine fire warning. It would appear to be a -200 combi variant with rear cargo door. Faint 'Air France' titles are visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What aircraft and flight was this?&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="22726" LastEditDate="2019-01-19T04:41:17.320" LastActivityDate="2019-11-07T18:06:18.720" Title="What Boeing 747 rejected takeoff and runway excursion accident is detailed in this video?" Tags="&lt;accidents&gt;&lt;rejected-takeoff&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="15998" PostTypeId="2" ParentId="15997" CreationDate="2015-06-18T07:34:13.640" Score="12" Body="&lt;p&gt;The copilot rejected the takeoff above V1 in response to the engine fire warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft in question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air France plane operating as flight 187&lt;/li&gt;&#xA;&lt;li&gt;Boeing 747-200 SCD (side cargo door) registration N4506H &lt;/li&gt;&#xA;&lt;li&gt;Aircraft had company number 22794 and manufacturer serial number 558. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The incident occurred on the 24 of July 1988 at Delhi airport. An overview can be found &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19880724-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="917" LastEditDate="2019-11-07T18:06:18.720" LastActivityDate="2019-11-07T18:06:18.720" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="15999" PostTypeId="2" ParentId="15942" CreationDate="2015-06-18T07:51:29.930" Score="7" Body="&lt;p&gt;Missiles use advanced algorithms to predict the best path to intercept the target. The seeker-head in the missile will be looking at the target (either IR, reflected radar energy, or using it's own radar depending on the missile type) and attempt to guide itself to the predicted intercept point, in order to have the shortest possible distance to cover. It basically flies towards an intercept point ahead of the target aircraft. When the target aircraft direction changes, so does this predicted intercept point, and the missile manoeuvres to fly towards the new intercept point. this is of course a continuous event. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore missiles usually have multiple stages of guidance. In the beginning they will fly just in the general direction in order to save energy, and only in the later stages will it start manoeuvring to the intercept point.&lt;/p&gt;&#xA;" OwnerUserId="8743" LastActivityDate="2015-06-18T07:51:29.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16000" PostTypeId="1" AcceptedAnswerId="16001" CreationDate="2015-06-18T09:16:42.793" Score="1" ViewCount="149" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;To squeeze more profits from each plane, the airline industry in the&#xA;  last few years has begun to install extra rows of seats,  leading to a&#xA;  crunch in legroom that has sparked tiffs and feuds among frustrated&#xA;  passengers. (&lt;a href=&quot;http://www.latimes.com/business/la-fi-narrower-airline-seats-20150206-story.html&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus has suggested 3-5-3 configuration for A380, making airlines&#xA;  have many extra seats.&lt;a href=&quot;http://www.usatoday.com/story/todayinthesky/2015/04/16/airbus-pitches-adding-an-extra-seat-to-every-row-in-its-a380s/25867611/&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A similar plan is there for the B777. Is it likely that airlines will pass on some of greater earnings to their passengers, in return of the lack of comfort?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-06-18T10:07:44.997" Title="Manufacturers are narrowing seats. Any possibilities for price cut?" Tags="&lt;commercial-aviation&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-06-18T11:43:09.410" ContentLicense="CC BY-SA 3.0" />
  <row Id="16001" PostTypeId="2" ParentId="16000" CreationDate="2015-06-18T10:07:44.997" Score="2" Body="&lt;p&gt;You will likely not see a price cut, but you also might not see a price increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seat pricing (along with just about any other service in a competitive market) is a complex function of actual cost to the company + desired profit + market factor. The last one is the difference between what they want to get and what the market is willing to pay. It is sometimes negative. &lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-18T10:07:44.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16003" PostTypeId="2" ParentId="15993" CreationDate="2015-06-18T13:27:34.613" Score="4" Body="&lt;p&gt;There can be a number of websites which can provide this information. Wikipedia and the specific airline's website can be a great resource too.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://openflights.org/&quot;&gt;OpenFlights&lt;/a&gt; gives you a graphical representation of direct flights from a particular airport. It appears that this service is for all major airports across the globe.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.skyscanner.net/airports/airports-of-the-world.html&quot;&gt;SkyScanner&lt;/a&gt; can provide the information you are looking for. As for your example, you'll enter Las Vegas in the &lt;code&gt;From&lt;/code&gt; text area, and then leave the &lt;code&gt;To&lt;/code&gt; area blank. It will search &lt;strong&gt;all&lt;/strong&gt; destinations (grouped by countries) where there are direct flights (or with one stop) available.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-06-18T13:37:45.227" LastActivityDate="2015-06-18T13:37:45.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16004" PostTypeId="1" AcceptedAnswerId="16006" CreationDate="2015-06-18T14:24:55.250" Score="10" ViewCount="4342" Body="&lt;p&gt;There have been several news reports about aircraft (light planes and helicopters) flying without visible registration numbers or identifying marks in the USA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NYPD referred to the helicopter only as “23”—a reference to the&#xA;  number of police officers killed in the 9/11 terrorist attacks—and&#xA;  initially the aircraft had no registration number painted on its tail&#xA;  or side. &lt;a href=&quot;http://www.wired.com/2015/06/fbi-not-alone-in-operating-secret-spycraft/&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cimbolic was beginning to worry that he had overreacted when he&#xA;  noticed, on the same flight-radar Web site, the second plane flying&#xA;  higher in the sky, carving bigger loops above West Baltimore. The Web&#xA;  site reported that this plane was a Cessna 560 Citation V, a small&#xA;  jet. But it showed no tail number, offering no possible trail to&#xA;  Federal Aviation Administration records. This only heightened his&#xA;  curiosity. &lt;a href=&quot;http://www.washingtonpost.com/business/technology/surveillance-planes-spotted-in-the-sky-for-days-after-west-baltimore-rioting/2015/05/05/c57c53b6-f352-11e4-84a6-6d7c67c50db0_story.html&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Eventually these aircraft were identified (and in the case of the former, a registration number found). But the general question I have is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are non-military aircraft allowed to fly without visible registration numbers (tail numbers) in the United States?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Fine print: I am aware that military planes usually have visible tail numbers, this question is about non-military craft. So &quot;non-military&quot; in this case includes federal agencies and state and local police. &lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="19" LastEditDate="2017-09-19T15:44:37.530" LastActivityDate="2019-06-11T18:53:24.140" Title="Are non-military aircraft allowed to fly with no registration numbers (tail numbers)?" Tags="&lt;faa-regulations&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16005" PostTypeId="1" AcceptedAnswerId="16243" CreationDate="2015-06-18T14:41:26.983" Score="10" ViewCount="883" Body="&lt;p&gt;At the Charlotte airport, I caught a glimpse of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bellanca_14-7&quot; rel=&quot;noreferrer&quot;&gt;Bellanca 14-9L&lt;/a&gt; with State Airlines livery they have on display. They call the Bellanca the first plane with retractable landing gear but that's not what struck my attention:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1qUge.jpg&quot; alt=&quot;Bellanca 14-9L&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a ram air turbine generator visible  and permanently located between the landing gear (circled). I only know of RATs as providing emergency power for airliners -- and they are only deployed (pushed outside) when they are needed. The other use for them is apparently on cropdusters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why did this airplane need a RAT permanently installed? Wouldn't it be much more power efficient and aerodynamic to provide DC/AC power through a magneto or alternator on the engine? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Late note: I looked at pictures of other Bellanca 14-9L and they don't show a RAT. Perhaps this means that this plane was not a passenger craft (as its &quot;State Airlines&quot; livery indicates) but was in real life a cropduster?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Photo by author. Released cc by-sa)&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-06-18T14:47:38.787" LastActivityDate="2015-06-24T17:14:59.513" Title="Why an external RAT on this early propeller plane at Charlotte?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16006" PostTypeId="2" ParentId="16004" CreationDate="2015-06-18T14:43:32.543" Score="13" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d8bf6dbd1bc9268a756cc2fb3f79a54a&amp;amp;mc=true&amp;amp;node=pt14.1.45&amp;amp;rgn=div5&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 45&lt;/a&gt; subpart C governs the display of &quot;nationality and registration marks&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 45.21 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except as provided in §45.22, no person may operate a U.S.-registered aircraft unless that aircraft displays nationality and registration marks in accordance with the requirements of this section and §§45.23 through 45.33. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 45.22 gives some exceptions for &quot;exhibition and antique&quot; aircraft, and for aircraft of unusual design that may need an alternative marking scheme.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume there is another regulation, or international agreement, requiring that foreign-registered aircraft must also display their registration marks, but I haven't found it yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to which aircraft have to be US-registered in the first place, see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d8bf6dbd1bc9268a756cc2fb3f79a54a&amp;amp;mc=true&amp;amp;node=pt14.1.47&amp;amp;rgn=div5&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 47&lt;/a&gt;.  It's a bit complicated.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US military is generally not bound by FAA regulations (though they may choose to follow some of them), see &lt;a href=&quot;https://aviation.stackexchange.com/questions/12401/how-much-jurisdiction-does-the-faa-have-over-military-aircraft&quot;&gt;How much jurisdiction does the FAA have over military aircraft?&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2546" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-06-18T14:43:32.543" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16007" PostTypeId="1" CreationDate="2015-06-18T19:11:12.373" Score="1" ViewCount="24754" Body="&lt;p&gt;What is the cost of the engine Boeing 747 Model 400?&#xA;Including what component of the cost of the aircraft engine Gies&lt;/p&gt;&#xA;" OwnerUserId="6967" LastActivityDate="2015-06-19T19:36:34.917" Title="What is the cost of the engine Boeing 747 Model 400?" Tags="&lt;engine&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-06-18T22:45:32.877" ContentLicense="CC BY-SA 3.0" />
  <row Id="16009" PostTypeId="1" AcceptedAnswerId="16010" CreationDate="2015-06-18T19:22:49.000" Score="4" ViewCount="609" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;nofollow&quot;&gt;Concorde&lt;/a&gt; had a maximum speed of 2.05 Mach, carrying about 96-128 passengers. The Airbus &lt;a href=&quot;https://en.wikipedia.org/?title=Airbus_A380&quot; rel=&quot;nofollow&quot;&gt;A380&lt;/a&gt; can achieve a top speed of 0.95 Mach with more than 500 passengers on board. This means roughly 5 times more passengers can be accommodated by compromising half of the top speed. So, why does speed lose out so much to capacity that it ultimately becomes unfeasible to operate a supersonic airliner?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="14897" LastEditDate="2018-03-21T23:12:16.387" LastActivityDate="2018-03-22T16:12:58.790" Title="Why does speed lose out to capacity?" Tags="&lt;airspeed&gt;&lt;supersonic&gt;&lt;seating-capacity&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16010" PostTypeId="2" ParentId="16009" CreationDate="2015-06-18T19:46:05.027" Score="14" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Which means, roughly 5 times more passengers can be accommodated by compromising half of the top speed. So, why does speed loses out so much to capacity that it ultimately becomes unfeasible to operate a supersonic airliner?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think you are asking, &quot;why do supersonic aircraft have such low capacity&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To travel faster than the speed of sound you need to have a very sharp nose and minimal area exposed to the forward direction, to minimize the generation of shockwaves. Shockwaves are bad for people on the ground (the 'sonic boom' effect) and they are terrible for fuel efficiency. Second you really do not want to trap air on flat surfaces facing forwards, because the air will get squashed in the supersonic flow and heat up a lot (like when you blow up a bicycle tyre or a football it is warm afterwards, or when the space shuttle re-enters the atmosphere). Again this is an enormous drag and having hot air flowing around your aircraft causes problems with the structure (Concorde used to grow by 300 mm during flight because of the heat).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you cannot be wide and you cannot be tall (without being aerodynamically inefficient), you need to be very long if you want lots of people. And then you have other problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design and construction of Concorde was never a commercial project, it was funded by two governments almost as a vanity project, as a prototype or as an experiment. Then it was given for free to two airlines to use as they wanted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So unlike the A380 and the B747, no one has ever said &quot;now we try to maximize the economics and the capacity of our design&quot;: that never happened. All they ever asked was &quot;How do we make this work!?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas the subsonic aircraft get a lot of time, money and thought spent on how to make them more economical to use by filling them with more passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information I recommend this interview with a former Concorde pilot: &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot;&gt;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, Concorde was developed 40 years ago. Are some more efficient supersonic Airliners possible today?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am sure that these days a far more fuel efficient supersonic engine could be built for passenger operations. And I do believe there would be a market for it on say LON-NYC or even maybe LON-DXB. But designing supersonic aircraft is quite different to designing subsonic ones; and then you have all the difficulty of modern safety regulations without being able to demonstrate you are relying on old, proven designs; and then there are very few routes where it could work profitably so you have very high development and maintenance costs spread over a small number of airframes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, it isn't worth the risk to anyone to make it.&lt;/p&gt;&#xA;" OwnerUserId="8565" LastEditorUserId="8565" LastEditDate="2015-06-18T19:51:10.400" LastActivityDate="2015-06-18T19:51:10.400" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="16011" PostTypeId="1" AcceptedAnswerId="16017" CreationDate="2015-06-18T19:51:59.080" Score="9" ViewCount="33676" Body="&lt;p&gt;I'm asking this question because the only &lt;a href=&quot;http://studentpilot.com/interact/forum/archive/index.php/t-37879.html&quot;&gt;answer&lt;/a&gt; on the web right now is pretty old and I assume this is a common question. The above link refers to an &lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/&quot;&gt;FAA page&lt;/a&gt; that says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We are currently processing permanent Airmen Certificates for&#xA;  temporary certificates that were issued approximately May 3, 2015.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The above quote hasn't been updated in weeks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long does it normally take to get a new certificate in the mail? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it vary substantially? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a better place than the above link to get an idea of how long a certificate will take to be processed? &lt;/p&gt;&#xA;" OwnerUserId="4509" LastActivityDate="2017-09-06T12:34:23.950" Title="How long does it take to get your official FAA certificate in the mail?" Tags="&lt;faa&gt;&lt;pilot-certification&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16012" PostTypeId="1" CreationDate="2015-06-18T20:01:13.657" Score="19" ViewCount="685" Body="&lt;p&gt;Is it fully legal to have a GoPro attached to the outside of the aircraft during flight, in the UK? I've heard mixed answers, but I don't want to try it until I've got confirmation.&lt;/p&gt;&#xA;" OwnerUserId="8834" LastEditorUserId="19" LastEditDate="2015-06-19T08:56:13.730" LastActivityDate="2016-08-25T16:51:06.350" Title="What are the rules in the UK about attaching a GoPro camera to the outside of an aircraft?" Tags="&lt;general-aviation&gt;&lt;caa-uk-regulations&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16013" PostTypeId="2" ParentId="16009" CreationDate="2015-06-18T20:02:15.120" Score="1" Body="&lt;p&gt;I think this is a question about &quot;how to design/build an airplane&quot;...&#xA;First of all, the Concorde was designed to have a 2.05 mach velocity and carry on 96-128 passengers, and the A380 was designed to have a 0.95 mach velocity and carry on ~500 passengers.&#xA;This does not means that the A380 compromisses velocity over capacity. Someone could design and build an airplane to carry on the same amount of passengers as a A380, but fly as fast as the Concorde did. This hypothetical airplane must be VERY dificult and expensive to build and very expensive to operate, and surely non airport on Earth has ben build to handle it.&#xA;When you design an airplane, the first thing you must have in mind is &quot;what is this plane for?&quot;, because you are trying to &quot;supply a demmand&quot;, and not trying to see &quot;who would buy this s***t?&quot;.&#xA;When an airline buys a plane, they have in mind&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This plane is going to fly from this airport to that specific airport in that specific path.&lt;/li&gt;&#xA;&lt;li&gt;XXX amount of passengers are going to buy tickets.&lt;/li&gt;&#xA;&lt;li&gt;To maximize the incoms and minimize the outcomes the plane I should by is: ***&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;p&gt;The main reason that no commercial supersonic flights are aviable today is because the are very expensive and don't have many routes to cover. I mean, althou some airlanes would buy 3 or 4 &quot;Concorde like&quot; planes, any plane manufacturer will design and build just a houndred planes. It's just not profitable.&lt;/p&gt;&#xA;" OwnerUserId="8920" LastEditorUserId="8920" LastEditDate="2015-06-18T22:24:08.153" LastActivityDate="2015-06-18T22:24:08.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16014" PostTypeId="1" AcceptedAnswerId="16028" CreationDate="2015-06-18T20:08:22.767" Score="4" ViewCount="8084" Body="&lt;p&gt;&lt;a href=&quot;http://www.samchuiphotos.com/Concorde/ConcordeTripReport2.html&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; is a report of the last journey of Concorde from JFK-LHR, which mentions &quot;The highest altitude we reached was 58000 feet.&quot; Is this height aerodynamically feasible to reach?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="946" LastEditDate="2015-06-19T10:05:11.470" LastActivityDate="2015-06-19T13:34:26.540" Title="Did Concorde really fly above 55k feet as mentioned in this report?" Tags="&lt;altitude&gt;&lt;supersonic&gt;&lt;concorde&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16015" PostTypeId="2" ParentId="16009" CreationDate="2015-06-18T20:14:34.353" Score="6" Body="&lt;p&gt;There are a few questions here but ill mainly address this one &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, Concorde was developed 40 years ago. Are some more efficient supersonic Airliners possible today?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;First off there is &lt;a href=&quot;http://www.aerionsupersonic.com/&quot; rel=&quot;nofollow&quot;&gt;at least one company&lt;/a&gt; who has said they are working on this mainly for the high end market but working on it none the less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/?title=Boeing_2707&quot; rel=&quot;nofollow&quot;&gt;Boeing took a crack at it&lt;/a&gt; years ago but the program was eventually stopped. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary reason that no super sonic aircraft have been developed since the Concorde is because &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/apl/noise_emissions/supersonic_aircraft_noise/media/noise_policy_on_supersonics.pdf&quot; rel=&quot;nofollow&quot;&gt;the FAA prohibits super sonic flight over land.&lt;/a&gt; This means a few things. First off you limit your self to routes that are primarily if not only over water. Which means that you limit who you can sell the craft too. This of course makes it unattractive to a company from a production/cost stand point. Now you are probably thinking, why not fly sub sonic over land then hit the throttle when we turn out over water. This sounds great but generally the aerodynamics that make a super sonic plane a super sonic plane are not great at the lower speeds in the spectrum. Could something maybe be designed, sure, but the market is clearly limited.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cost is the main driving factor in aviation. It is cheap to develop a new car and bring it to market but planes require a much more stringent process which reflects in their price. As such airlines (and even GA consumers) want to get as much out of a plane (time wise) as they can. Supersonic aircraft experience &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde#Structural_issues&quot; rel=&quot;nofollow&quot;&gt;stresses&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde#Heating_issues&quot; rel=&quot;nofollow&quot;&gt;heat&lt;/a&gt; that their subsonic counter parts don't. This makes them unattractive to potential buyers since the planes need more support to be kept in the air.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3386" LastEditDate="2015-06-20T02:30:31.733" LastActivityDate="2015-06-20T02:30:31.733" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16016" PostTypeId="2" ParentId="16014" CreationDate="2015-06-18T20:17:37.980" Score="7" Body="&lt;p&gt;Yes. According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde#Specifications&quot;&gt;Wikipedia&lt;/a&gt;, Concorde's service ceiling was 60,000ft.&lt;/p&gt;&#xA;" OwnerUserId="2691" LastActivityDate="2015-06-18T20:17:37.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16017" PostTypeId="2" ParentId="16011" CreationDate="2015-06-18T20:28:47.087" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Airmen Certification page you linked to&lt;/a&gt; is the best place to get a quick status update - the little note at the top gets updated when they move into a new batch of certificates. You can also search for yourself &lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/interactive_airmen_inquiry/&quot; rel=&quot;nofollow noreferrer&quot;&gt;in the airmen certification database&lt;/a&gt;: When your new certificate or rating shows up there your certificate is probably in the mail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long it takes to get your permanent certificate depends mainly on how many they have in the queue ahead of you - Mine took about 60 days, but I've heard as little as 30 and as long as 100+.&lt;br&gt;&#xA;If you're getting close to the expiration of your temporary certificate you can request an extension either &lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/airmen_services/&quot; rel=&quot;nofollow noreferrer&quot;&gt;online&lt;/a&gt; or at your local FSDO (more details over on &lt;a href=&quot;https://aviation.stackexchange.com/questions/1573/what-happens-when-a-temporary-pilot-certificate-expires&quot;&gt;this answer&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-06-18T20:28:47.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16018" PostTypeId="2" ParentId="16007" CreationDate="2015-06-18T20:31:54.547" Score="4" Body="&lt;p&gt;The actual prices paid for an engine are likely to not be released publicly. However, list prices are advertised, and other sources may help give an idea of the price range for such engines. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-400&quot; rel=&quot;nofollow&quot;&gt;747-400&lt;/a&gt; model has three engine options available: PW 4056, GE CF6, and RR RB211. These engines are also used on other aircraft, which will help in finding the prices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CF6 engine has a list price of about $11 million (&lt;a href=&quot;http://www.geaviation.com/press/cf6/cf6_20090709.html&quot; rel=&quot;nofollow&quot;&gt;from an A330 order in 2009&lt;/a&gt;, higher thrust version; \$12.2 million in 2015 USD&lt;sup&gt;1&lt;/sup&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PW4056 engine has a price of $5.8 million (&lt;a href=&quot;https://books.google.com/books?id=Kp5kYHecqZIC&amp;amp;lpg=PA113&amp;amp;dq=4056&amp;amp;pg=PA113#v=onepage&amp;amp;q=4056&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;from a 1994 report&lt;/a&gt;; \$9.3 million in 2015 USD).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't found good pricing for the RB211. An older, lower thrust version was priced at £340,000 &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_RB211&quot; rel=&quot;nofollow&quot;&gt;in 1971&lt;/a&gt; (\$4.8 million in 2015 USD&lt;sup&gt;2&lt;/sup&gt;), &lt;a href=&quot;http://www.ebay.com/itm/Rolls-Royce-RB211-22B-Complete-Engine-with-Stand-/141666658773&quot; rel=&quot;nofollow&quot;&gt;or you could buy one right now for $35,000&lt;/a&gt; (the seller hopes it can be put on display, mentioning &quot;very high end art displays&quot; but also &quot;top dollar in scrap&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The list price for a 747-400 was about \$240 million, which means that 4 engines at a list price of \$10 million each would be about %17 of the cost of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;a href=&quot;http://www.usinflationcalculator.com/&quot; rel=&quot;nofollow&quot;&gt;Inflation calculator&lt;/a&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;&lt;a href=&quot;https://research.stlouisfed.org/fred2/data/EXUSUK.txt&quot; rel=&quot;nofollow&quot;&gt;exchange rate&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-06-19T19:36:34.917" LastActivityDate="2015-06-19T19:36:34.917" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16019" PostTypeId="2" ParentId="16014" CreationDate="2015-06-18T20:42:11.167" Score="3" Body="&lt;p&gt;As per its service celling that would not have been an issue. It should also be noted that Mach 1 (the speed of sound) is about &lt;a href=&quot;http://www.fighter-planes.com/jetmach1.htm&quot; rel=&quot;nofollow&quot;&gt;90 Knots Slower&lt;/a&gt; at that altitude. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-18T20:42:11.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16020" PostTypeId="1" CreationDate="2015-06-18T20:42:34.290" Score="3" ViewCount="7482" Body="&lt;p&gt;As a pilot who has just graduated, what are the ways to gain experience and flight hours?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing airline look at is your flight hours, they usually require 1200 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any chance for a fresh graduated pilot to get hired in an airline with only 250 hours of flying? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm graduated in the Philippines. &lt;/p&gt;&#xA;" OwnerUserId="5715" LastEditorUserId="19" LastEditDate="2017-03-02T16:32:45.357" LastActivityDate="2017-03-02T16:32:45.357" Title="What are good ways to gain experience and flying hours?" Tags="&lt;student-pilot&gt;&lt;airline-pilot&gt;&lt;philippines&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16021" PostTypeId="2" ParentId="16014" CreationDate="2015-06-18T20:42:41.627" Score="7" Body="&lt;p&gt;The density will go down a bit at that altitude compared to normal aircraft, but your airspeed is Mach 2, so that's good. Lift is (among others) a factor of both parameters. Be aware that there is a bit more going on though with supersonic stuff as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An increasing number of aircraft are approaching this altitude domain. For instance, the subsonic corporate Gulfstream G650 tops at 51,000ft.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1699" LastEditDate="2015-06-19T12:35:55.207" LastActivityDate="2015-06-19T12:35:55.207" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16022" PostTypeId="1" CreationDate="2015-06-18T22:09:48.800" Score="0" ViewCount="3263" Body="&lt;p&gt;How I can calculate the fuselage midsection having a constraint length? Also, if I want a cross section shaped like an Antonov that on top of it have a lower ratio than the bottom, as that is part or can do the calculations to determine the area in front.&lt;/p&gt;&#xA;" OwnerUserId="8044" LastActivityDate="2017-05-10T09:46:33.007" Title="How to calculate the fuselage geometrical parameters?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;fuselage&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16023" PostTypeId="1" CreationDate="2015-06-19T00:07:12.627" Score="2" ViewCount="1677" Body="&lt;p&gt;The JF-17 Thunder is a fighter jet which has been developed with the joint collaboration of Pakistan and China. There has been a lot of hype about this aircraft in recent years. Pakistani and Chinese authorities are aggressively searching for customers for this aircraft. Recently they have got some orders from an Air Force of an undisclosed Asian country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the JF-17 merely an upgraded Mig-21/F-7 (like Mig-21 Bison), or is it a whole new aircraft?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="1467" LastEditDate="2018-04-20T09:05:18.170" LastActivityDate="2018-04-20T09:05:18.170" Title="Is JF-17 a reconfigured Mig-21/F-7?" Tags="&lt;fighter&gt;&lt;china&gt;&lt;pakistan&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16024" PostTypeId="2" ParentId="16020" CreationDate="2015-06-19T03:53:28.587" Score="6" Body="&lt;p&gt;There are a few ways to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has been mentioned many people here in the US are flight instructors (my instructor is building hours to go commercial eventually). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has also been mentioned you could build hours taking trips with friends and splitting the cost but even split 3 or 4 ways this can get expensive fast. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could do things like tow gliders or banners if they have that kind of advertising near you. It's not glorious and I can't imagine it's that fun as far as flying goes but it will build you hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure how to get into flying planes for sky diving tours but that is another option to just build hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again your hours may be an issue but you could look into ferrying planes for people. This can be tough if you don't have a lot of experience in different planes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are just a few things that come to mind. There may be varying laws in your area so its worth checking up on that before trying any of these things.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2015-12-31T06:21:50.827" LastActivityDate="2015-12-31T06:21:50.827" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16025" PostTypeId="1" CreationDate="2015-06-19T06:03:05.440" Score="7" ViewCount="199" Body="&lt;p&gt;Normally 10,000 ft is considered safe altitude for emergency descents and 12,000 ft a maximum that can be flown in unpressurised aircraft without using supplementary oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when flying in the mountains with a crew that normally lives at say 5,000 ft or more, can they afford higher altitude? And by how much?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The 12,000 ft I've seen somewhere, but I don't know whether it is actually a regulation or just recommendation.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-19T14:59:30.410" LastActivityDate="2015-06-19T14:59:30.410" Title="Does maximum altitude increase when pilot is acclimatised?" Tags="&lt;mountain-flying&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16026" PostTypeId="1" CreationDate="2015-06-19T06:30:51.383" Score="2" ViewCount="635" Body="&lt;p&gt;An important tourist connection goes from Tribhuvan International Airport (VNKT) in Kathmandu, at 4,390 ft, to Tenzing-Hillary Airport (VNLK) in Lukla, at 9,334 ft. The mountains around Lukla quickly raise from south to north. Right around Lukla the ridges rise to about 15,000 ft, but the aircraft does not have to fly over these, since decent approach is only possible through the valley from the south and the ridges are somewhat lower further south. So does anybody know what is actual typical cruise altitude in that area?&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-19T11:32:55.170" Title="What is typical cruise altitude in the Himalayas?" Tags="&lt;mountain-flying&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16027" PostTypeId="2" ParentId="16026" CreationDate="2015-06-19T07:51:48.613" Score="0" Body="&lt;p&gt;You need to be between 13k - 9.1k ft for the Kathmandu to Lukla flight. This &lt;a href=&quot;http://www.simtours.net/mounteverest.php&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt; would probably answer your question.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-19T07:51:48.613" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16028" PostTypeId="2" ParentId="16014" CreationDate="2015-06-19T07:57:04.353" Score="12" Body="&lt;p&gt;Yes. The extra height was necessary in order to reach lower pressure air, and thereby reduce drag, and heating of the airframe from supersonic compression of the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde's windows were extra small, so that if a window did blow out, the air compression system could actively compensate by pumping air in faster than it could escape, until the pilot completed his emergency descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More details can be heard &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot;&gt;on this podcast&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8565" LastEditorUserId="65" LastEditDate="2015-06-19T13:34:26.540" LastActivityDate="2015-06-19T13:34:26.540" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16029" PostTypeId="5" CreationDate="2015-06-19T09:12:23.377" Score="0" Body="" OwnerUserId="8547" LastEditorUserId="946" LastEditDate="2015-06-26T20:57:49.383" LastActivityDate="2015-06-26T20:57:49.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16030" PostTypeId="4" CreationDate="2015-06-19T09:12:23.377" Score="0" Body="Questions relating to aviation in China." OwnerUserId="8547" LastEditorUserId="946" LastEditDate="2015-06-26T20:58:03.240" LastActivityDate="2015-06-26T20:58:03.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16031" PostTypeId="5" CreationDate="2015-06-19T09:14:35.620" Score="0" Body="" OwnerUserId="8547" LastEditorUserId="946" LastEditDate="2015-06-26T21:06:31.277" LastActivityDate="2015-06-26T21:06:31.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16032" PostTypeId="4" CreationDate="2015-06-19T09:14:35.620" Score="0" Body="Questions relating to aviation in Pakistan." OwnerUserId="8547" LastEditorUserId="946" LastEditDate="2015-06-26T20:58:00.307" LastActivityDate="2015-06-26T20:58:00.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16034" PostTypeId="1" CreationDate="2015-06-19T10:37:27.353" Score="19" ViewCount="11838" Body="&lt;p&gt;What tools are being used by airports to measure visibility precisely? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do we have some kind of tools on aircraft as well for measuring visibility?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="-1" LastEditDate="2015-06-19T14:29:11.650" LastActivityDate="2019-07-16T06:17:40.590" Title="How is the visibility at airports measured?" Tags="&lt;visibility&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16035" PostTypeId="2" ParentId="16034" CreationDate="2015-06-19T10:51:30.357" Score="25" Body="&lt;p&gt;The visibility is measured alongside the runway, usually at various positions, and is called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway_visual_range&quot; rel=&quot;noreferrer&quot;&gt;Runway Visual Range (RVR)&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;RVR is defined as the range over which the pilot of an aircraft on the centre line of a runway can see the runway surface markings or the lights delineating the runway or identifying its centre line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RVR is measured using so called transmissometers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ejiHZ.jpg&quot; alt=&quot;Transmissometer&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.keesfloor.nl/weerkunde/7zicht/7zicht.htm&quot; rel=&quot;noreferrer&quot;&gt;source: keesfloor.nl&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These units transmit a beam of light (usually using laser) to a detector. In some case the transmitter and detector are in the same unit and a reflector is used. The ratio of the transmitted energy and the detected energy is a measure of how much light is absorbed in the fog. From this the RVR can be calculated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another type of sensor used to measure the visibility on airports is a forward scatter sensor. This type of sensor can be mounted on a single mast and gives more accurate results for visibilities &gt; 2 km. This kind of sensor is used for both determining RVR and Meteorological Optical Range (MOR).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/P5KgX.png&quot; alt=&quot;Forward scatter sensor&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&#xA;&lt;a href=&quot;http://www.knmi.nl/~wauben/Sensor/TECO2012_Wauben_Insects_reduced_MOR.pdf&quot; rel=&quot;noreferrer&quot;&gt;source: KNMI (PDF)&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type of sensor works by detecting how much of the transmitted light is scattered into a detector which is placed off-axis. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aircraft don't have means to measure the visibility other than the pilot Mk 1 eyeball. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="65" LastEditDate="2015-06-19T13:44:43.810" LastActivityDate="2015-06-19T13:44:43.810" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16036" PostTypeId="1" AcceptedAnswerId="16043" CreationDate="2015-06-19T11:30:21.573" Score="3" ViewCount="12916" Body="&lt;p&gt;I think there are multiple variants of engines for the different variants in B777 family but I am not sure but is it GE90-115B in one while Trent and PW in others?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2016-12-16T14:48:28.063" Title="Do all B777 family aircraft have the same engines?" Tags="&lt;engine&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16037" PostTypeId="2" ParentId="16026" CreationDate="2015-06-19T11:32:55.170" Score="3" Body="&lt;p&gt;I am sure I have no knowledge for reading charts but en-route charts for Nepal indicate something like F170 which I translate to FL170 or 17,000 ft. Pls correct me if I misunderstand it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the &lt;a href=&quot;http://e-aip.caanepal.org.np/_uploads/_pdf/f79fd896b77b811f5790e0ad7d81842f.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/hZkaD.jpg&quot; alt=&quot;Nepal enroute chart&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-06-19T11:32:55.170" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16038" PostTypeId="1" CreationDate="2015-06-19T11:33:50.700" Score="7" ViewCount="549" Body="&lt;p&gt;Is it possible to have to have two different makes of engines which are generating almost similar thrust for a twin-engine aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-06-19T13:00:22.313" Title="Is it possible to have two different makes of engine on a single twin-engine aircraft?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16039" PostTypeId="2" ParentId="16036" CreationDate="2015-06-19T11:35:32.460" Score="5" Body="&lt;p&gt;From a &lt;a href=&quot;https://aviation.stackexchange.com/a/9345/19&quot;&gt;related answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Boeing 777-300ER is always equipped with General Electric&#xA;  GE90-115BL1 engines, while the baseline -300 can be ordered with four&#xA;  different engine models from General Electric, Pratt&amp;amp; Whitney or Rolls&#xA;  Royce. The Emirates Boeing 777-300 aircraft have the Rolls Royce RR&#xA;  Trent 892 engines installed. They deliver 415 kN of thrust, almost 100&#xA;  kN less than the GE90-115BL1 engines.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When a customer orders a Boeing 777-300 they can pick their choice of the four engines available for that model. When they order a Boeing 777-300ER they will get the GE engine. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-06-19T11:43:03.350" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16040" PostTypeId="2" ParentId="16038" CreationDate="2015-06-19T12:42:19.467" Score="5" Body="&lt;p&gt;Yes it is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Boeing 777-200ER using GE engines . The first engine = GE90-94B and the second engine = GE90-115B .&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is called engine intermixing.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 737 sometimes The more powerful engine is derated to the same level as the other engine, and we had to do full power takeoffs everytime. As long as the FMC is aware of the intermix, pilots are allowed to use autothrottle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here are the sources for your further reading : &#xA;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/115780/&quot;&gt;Source 1&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.oaviao.com/pesquisa_codigo_empresas/manuais_voo/performance_airbus/Engine_intermix.html&quot;&gt;Source 2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following is another example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Models with engine intermix already certified&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Aircraft models / Engines        Engines allowed&#xA;&#xA;A310-221 / PW JT9D-7R4D1         1 or 2 JT9D-7R4E1&#xA;(48000 lb *)                     50000 lb*&#xA;                                 (A310-222)&#xA;&#xA;A310-222 / PW JT9D-7R4E1         1 or 2 JT9D-7R4D1&#xA;(50000 lb *)                     48000 lb *&#xA;                                 (A310-221)&#xA;&#xA;A310-308 / GE CF6-80C2A8         1 or 2 CF6-80C2A2&#xA;(57860 lb*)                      52460 lb*  &#xA;                                 (A310-304)&#xA;&#xA;A300B4-605R / GE CF6-80C2A5      1 or 2 CF6-80C2A3&#xA;(60200 lb*)                      58950 lb*&#xA;                                 (A300B4-603)&#xA;&#xA;Note (*): Static thrust limit at sea level for takeoff with OAT 30°C.&#xA;&#xA;For these aircraft models, the new engine(s) is (are) installed with no hardware change nor rating change.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-19T13:00:22.313" LastActivityDate="2015-06-19T13:00:22.313" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16041" PostTypeId="2" ParentId="16036" CreationDate="2015-06-19T12:50:14.797" Score="3" Body="&lt;p&gt;Though @DeltaLima has already answered your question, I'd like to source my information from &lt;a href=&quot;https://en.wikipedia.org/?title=Boeing_777#777-200&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following engine options are available for various 777 variants:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;777-200    : PW4077 , RR877 , GE90-77B&lt;/li&gt;&#xA;  &lt;li&gt;777-200ER  : PW 4090 , RR 895, GE90-94B&lt;/li&gt;&#xA;  &lt;li&gt;777-200LR  : GE90-110B1 , GE90-115B1&lt;/li&gt;&#xA;  &lt;li&gt;777 Freighter: GE90-110B1 , GE90-115B1&lt;/li&gt;&#xA;  &lt;li&gt;777-300    : PW 4098 , RR 892 , GE90-92B/-94B&lt;/li&gt;&#xA;  &lt;li&gt;777-300ER  : GE90-115B1&lt;/li&gt;&#xA;  &lt;li&gt;777-8X     : GE9X&lt;/li&gt;&#xA;  &lt;li&gt;777-9X     : GE9X&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-19T12:50:14.797" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16042" PostTypeId="1" CreationDate="2015-06-19T13:07:40.790" Score="13" ViewCount="2652" Body="&lt;p&gt;There are some plane designs where the engines are placed quite far away from the fuselage, one example is the SR-71.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/beZV9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This amplifies the effects of any asymmetry of the engine thrusts, the worst case being zero thrust on one side. What are the reasons that justify or force those designs?&lt;/p&gt;&#xA;" OwnerUserId="2345" LastEditorUserId="167" LastEditDate="2015-06-20T18:49:22.990" LastActivityDate="2015-06-20T18:49:22.990" Title="Why locate engines far from the fuselage in some aircraft, such as the SR-71?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16043" PostTypeId="2" ParentId="16036" CreationDate="2015-06-19T13:12:48.017" Score="14" Body="&lt;p&gt;TL;DR: No.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For the true answer refer to the FAA &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e3a891bd1c8a006986257d8e005b93fe/$FILE/T00001SE_Rev_37.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Type Certificate Data Sheet&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777-200&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 Pratt and Whitney Turbofan Model:&#xA;PW4074, PW4074D, PW4077, PW4077D,PW4090,PW4084D, and PW4090-3&#xA;(Engine Type Certificate No. E46NE)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-76B, GE90-85B, GE90-90B, GE90-94B&#xA;(Engine Type Certificate No. E00049EN)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 Rolls-Royce Turbofan Model: RB211-Trent 875-17, RB211-Trent, 877-17,&#xA;RB211-Trent 884-17, RB211-Trent 892-17, or RB211 Trent 892B-17, RB211 Trent 895-17&#xA;(Engine Type Certificate E00050EN) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777-300&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 Rolls-Royce Turbofan Model: RB211-Trent 884-17, RB211-Trent 884B-17,&#xA;or RB211-Trent 892-17&#xA;(Engine Type Certificate E00050EN)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 Pratt &amp;amp; Whitney Turbofan Model: PW4090, PW4098&#xA;(Engine Type Certificate E46N)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777-300ER&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-115B&#xA;(Engine Type Certificate No. E00049EN) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777-200LR&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-110B1&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-115B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Engine Type Certificate No. E00049EN) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;777F&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-110B1&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2 General Electric Turbofan Model: GE90-115B&#xA;(Engine Type Certificate No. E00049EN)&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="511" LastEditDate="2016-12-16T14:48:28.063" LastActivityDate="2016-12-16T14:48:28.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16044" PostTypeId="2" ParentId="16042" CreationDate="2015-06-19T13:21:39.217" Score="12" Body="&lt;p&gt;There are a couple of reasons which drive the need to place the engines at optimum distance from the fuselage. In case of Blackbird SR-71, the engines have to be placed at a distance such that they can ingest optimum amount of air for proper combustion. Placing the engines too close to the fuselage would hinder the air flow, and hence the engines might not work properly. The CONS of having such a placement, as mentioned in the question can be done away by having proper damping, and design techniques to reduce the effect of any kind of asymmetry.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-19T13:21:39.217" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16045" PostTypeId="2" ParentId="16025" CreationDate="2015-06-19T13:23:44.900" Score="4" Body="&lt;p&gt;Yes, maximum possible altitude at which a pilot can fly an Unpressurized Airplane without the need for supplementary oxygen does increase with acclimatisation. But the international aviation laws do not take this into account and hence they have a general altitude limit for unpressurized flying without supplementary oxygen.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-19T13:23:44.900" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16046" PostTypeId="2" ParentId="16042" CreationDate="2015-06-19T13:46:41.427" Score="15" Body="&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Podded_engine&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Placing engines on the wing provides beneficial wing bending relief in&#xA;  flight. The further the engines are away from the fuselage the greater&#xA;  the wing bending relief so engines buried in the wing root provide&#xA;  little relief. Almost all modern large jet airplanes use engines in&#xA;  pods located a significant distance from the wing root for substantial&#xA;  wing bending relief.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One could imagine that, in flight, the wings are holding up the aircraft, but this causes a massive bending moment at the wing roots (just visualize  an airplane suspended by ropes from the wings). As such, is favourable to have the airplane body be as light as possible, and put as much mass (e.g., fuel) as possible &lt;strong&gt;on&lt;/strong&gt; the wings, where the lift forces coincide (or at least, are closer to) the weight of the engine, reducing bending moment on the wing roots. This allows for smaller (and thus more aerodynamically efficient) wing structures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted in the comments, placing the engines further away of course increases downwards bending moment when the plane has landed. However, this will be 1g by definition (at touchdown, the wings still provide lift (&lt;a href=&quot;https://www.youtube.com/watch?v=aJ5uudaAPPY&quot;&gt;generally&lt;/a&gt;)), whereas during the flight, an airplane is designed to take &lt;a href=&quot;http://www.b737.org.uk/limitations.htm#Flight_Manoeuvring_Load_Acceleration_Limits&quot;&gt;up to 2.5g&lt;/a&gt; (and, I suppose not completely coincidentally, -1g).&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2015-06-19T15:45:31.250" LastActivityDate="2015-06-19T15:45:31.250" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16047" PostTypeId="1" AcceptedAnswerId="16049" CreationDate="2015-06-19T14:05:23.983" Score="4" ViewCount="5709" Body="&lt;p&gt;I have found the differences rather interesting between the Beechcraft Bonanza engine and a turboprop, I have heard there the same and they're different. But I need a straight answer.&lt;/p&gt;&#xA;" OwnerUserId="8960" LastEditorUserId="19" LastEditDate="2016-07-04T12:40:19.427" LastActivityDate="2016-07-04T12:40:19.427" Title="What is the difference between a propeller and a turbo propeller?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16049" PostTypeId="2" ParentId="16047" CreationDate="2015-06-19T14:30:59.347" Score="8" Body="&lt;p&gt;I think you are trying to ask &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the difference between a propeller and a turbo propeller?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A traditional propeller plane is powered by an &lt;a href=&quot;https://en.wikipedia.org/wiki/Reciprocating_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;reciprocating (piston)&lt;/a&gt; engine. These can be in the form of radial, flat, or V style engines with a few other configurations used here and there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gvqyX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand a turbo prop is a propeller plane that is powered by a &lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;turbine engine&lt;/a&gt;. In this instance the shaft of the turbine is used to drive a propellor. One could think of this as putting a propellor on the front of a jet engine.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sRGel.jpg&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3825" LastEditDate="2015-06-20T00:57:23.257" LastActivityDate="2015-06-20T00:57:23.257" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16051" PostTypeId="1" AcceptedAnswerId="16053" CreationDate="2015-06-19T16:22:56.950" Score="2" ViewCount="738" Body="&lt;p&gt;I'm intrigued by the Lockheed SR-71's take-off procedure, as it seems different to that of civilian aircraft. I would like to know what are the major differences in take-off procedure, and why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, most aircraft begin to take off like the following: &lt;em&gt;engine one on, warming up. Engine two on, warming up, etc.&lt;/em&gt; But is this the same for the SR-71 what was its take-off protocol?&lt;/p&gt;&#xA;" OwnerUserId="8960" LastEditorUserId="8960" LastEditDate="2015-11-20T19:16:55.480" LastActivityDate="2015-11-20T19:16:55.480" Title="Lockheed SR-71 take off protocol" Tags="&lt;military&gt;&lt;takeoff&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2015-06-19T19:31:31.373" ContentLicense="CC BY-SA 3.0" />
  <row Id="16053" PostTypeId="2" ParentId="16051" CreationDate="2015-06-19T17:15:31.180" Score="7" Body="&lt;p&gt;If you are referencing the &lt;a href=&quot;http://www.sr-71.org/blackbird/manual/2/&quot;&gt;manuals found here&lt;/a&gt; the procedures look pretty standard to me. Granted they involve some thing specific to the plane they are generally what one would find. Pages &lt;a href=&quot;http://www.sr-71.org/blackbird/manual/2/2-19.php&quot;&gt;2-19&lt;/a&gt; through &lt;a href=&quot;http://www.sr-71.org/blackbird/manual/2/2-23.php&quot;&gt;2-23&lt;/a&gt; seems to cover the start up procedure and it looks pretty standard. Make sure ground unit is connected, check fuel flow, check engine is open, start, check RMP (provides some trouble shooting for RPM issues as well). It also goes on to say left engine first for odd flights and right engine first for even flights to keep the wear some what in line. There are a lot of &quot;Note&quot; sections but you are talking about one of if not the highest performance aircraft ever made so these are to be expected.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-19T17:15:31.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16057" PostTypeId="2" ParentId="16023" CreationDate="2015-06-19T20:39:37.320" Score="2" Body="&lt;p&gt;JF-17 is certainly not a mig-22/f7 derivative. It's a generation ahead of those aircraft, a whole new aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of capabilities, it is designed to give maximum bang for buck while keeping multi-role capabilities. It's got BVR missiles, an impressive array of stand off weapons for strike purposes, so on etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It comes with no political strings attached, like western aircraft often do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a low risk investment with decent capabilities, certainly no where near the latest F-16s in terms of capabilities, money or political strings.&lt;/p&gt;&#xA;" OwnerUserId="8965" LastEditorUserId="7532" LastEditDate="2017-12-15T16:35:54.993" LastActivityDate="2017-12-15T16:35:54.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16059" PostTypeId="1" AcceptedAnswerId="16084" CreationDate="2015-06-19T21:08:23.443" Score="7" ViewCount="953" Body="&lt;p&gt;So it is my understanding that on most commercial jets, the airline has a choice of multiple engine types, such as GE or P&amp;amp;W, etc. My question would be why an airline would choose one type over the other. Also if there is a &quot;better&quot; choice, why would the airlines choose one of the others?&lt;/p&gt;&#xA;" OwnerUserId="7373" LastEditorUserId="19" LastEditDate="2016-07-04T12:33:27.770" LastActivityDate="2016-07-04T12:33:27.770" Title="What trade-offs does an airline make when selecting an engine type for their aircraft?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;jet-engine&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16060" PostTypeId="1" CreationDate="2015-06-19T23:25:46.680" Score="8" ViewCount="1233" Body="&lt;p&gt;Regardless of the degree of collective pitch applied, the cyclic pitch controls must retain their full range. Both controls are via jacks, so how are the jacks connected?&lt;/p&gt;&#xA;" OwnerUserId="8967" LastEditorUserId="167" LastEditDate="2015-06-20T18:48:36.743" LastActivityDate="2017-06-01T14:27:56.610" Title="How are helicopter cyclic and collective jacks connected?" Tags="&lt;helicopter&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16063" PostTypeId="1" CreationDate="2015-06-20T00:33:51.940" Score="7" ViewCount="1781" Body="&lt;p&gt;If I have my instrument rating can I log simulated instrument time under the hood while flying alone as the PIC? Or does a safety pilot have to be present?&lt;/p&gt;&#xA;" OwnerUserId="8969" LastEditorUserId="19" LastEditDate="2016-07-04T12:35:40.710" LastActivityDate="2016-07-04T12:35:40.710" Title="Can I fly solo when practicing IFR under the hood?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2020-09-11T14:05:45.993" ContentLicense="CC BY-SA 3.0" />
  <row Id="16065" PostTypeId="1" AcceptedAnswerId="16070" CreationDate="2015-06-20T04:59:58.723" Score="7" ViewCount="652" Body="&lt;p&gt;It seems like on an electric aircraft, it would be very important to have a high energy efficiency. Wouldn't the &lt;a href=&quot;http://www.e-volo.com/&quot; rel=&quot;nofollow&quot;&gt;e-volo copter&lt;/a&gt; be much less efficient due to the small radius of the propellers when compared to a traditional helicopter?&lt;/p&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="19" LastEditDate="2017-09-19T15:44:23.180" LastActivityDate="2017-11-11T14:33:08.087" Title="How much energy/prop efficiency does the e-volo copter sacrifice by having a smaller propeller?" Tags="&lt;helicopter&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16067" PostTypeId="1" AcceptedAnswerId="16072" CreationDate="2015-06-20T08:51:26.843" Score="5" ViewCount="1363" Body="&lt;p&gt;I know that passengers are asked to put their cell phones on flight mode. But some carriers allow use of WLAN on-board. So, what radios should passengers refrain from using?&#xA;Also, if a person uses a GPS receiver on his/her mobile phone (on flight mode), would it interfere with the aircraft communication system?&lt;/p&gt;&#xA;" OwnerUserId="8972" LastActivityDate="2016-12-26T22:47:40.690" Title="Exactly what kind of radios are prohibited for passengers inside an aircraft?" Tags="&lt;gnss&gt;&lt;radio&gt;" AnswerCount="3" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="16068" PostTypeId="2" ParentId="16063" CreationDate="2015-06-20T13:35:40.140" Score="17" Body="&lt;p&gt;Before going into the FAR AIM, take a second to think about this idea:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are in your airplane, under the hood, flying along your route or wherever. The only traffic warnings you will get are from your controller, and he does not always see all the VFR traffic on his screen... Not a good idea. Definitely never fly without a safety pilot under the hood in VMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets open the FAR AIM:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.109 Flight instruction; Simulated instrument flight and certain&#xA;  flight tests&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No person my operate a civil aircraft in simulated instrument&#xA;  flight unless - &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The other control seat is occupied by a safety&#xA;  pilot who possesses at least a private pilot certificate with category&#xA;  and class ratings appropriate to the aircraft being flown.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The safety pilot has adequate vision forward and to each side of&#xA;  the aircraft, or a competent observer in the aircraft adequately&#xA;  supplements the vision of the safety pilot; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Except in the case of lighter-than-air aircraft, that aircraft is&#xA;  equipped with fully functioning dual controls. However, simulated&#xA;  instrument flight may be conducted in a single-engine airplane,&#xA;  equipped with a single, functioning, throwover control wheel, in place&#xA;  of fixed, dual controls of the elevator and ailerons, when—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) The safety pilot has determined that the flight can be conducted&#xA;  safely; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) The person manipulating the controls has at least a private pilot&#xA;  certificate with appropriate category and class ratings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Getting the important stuff out of there: &lt;code&gt;No person may operate a civil aircraft in simulated instrument flight unless the other control seat is occupied by a safety pilot!&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAR/AIM part obviously only goes for FAA regions, but I'm assuming that is what you are asking about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion: According to logic thinking you should never ever not look out the window in VMC, and the FAA doesn't allow you to either, not even for IFR recency!&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2015-06-20T13:35:40.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16070" PostTypeId="2" ParentId="16065" CreationDate="2015-06-20T13:45:21.287" Score="9" Body="&lt;p&gt;What counts is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc&quot;&gt;mass of air which is available for lift/thrust creation&lt;/a&gt;. Several smaller props would still offer about the same area for lift creation as a single rotor, so in this respect that design is not at a disadvantage. The smaller props will have to spin faster than a single rotor to have the same average dynamic pressure, and the lift distribution over the whole area covered by propellers will be less asymmetric at forward speed than it is over the disc of a single rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What should reduce the efficiency, however, is the smaller &lt;a href=&quot;https://en.wikipedia.org/?title=Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds number&lt;/a&gt; of the blades. Even if the blade airfoil is carefully optimized for their small Reynolds number, I would expect that at least 10% more energy is needed for the same lift compared to a conventional helicopter. The smaller inertia of the blades, however, is a big advantage in control, because the smaller propellers can be spun up or down faster, avoiding the more complex rotor head of conventional helicopters. With a modern FCS the e-volo should be controllable by individually adjusting prop speed alone. The electric motors most likely are capable of short-term torque bursts which far exceed their continuous performance, so control responsiveness should be adequate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The smaller moment of inertia of the propellers becomes a liability in an emergency, because the e-volo arrangement is less capable of an &lt;a href=&quot;https://aviation.stackexchange.com/questions/7522/what-is-the-relationship-between-blade-inertia-and-rotor-kinetic-energy&quot;&gt;autorotation landing&lt;/a&gt; in case the energy supply fails. That is probably the reason why the &lt;a href=&quot;http://www.e-volo.com/information/safety-concept&quot; rel=&quot;nofollow noreferrer&quot;&gt;e-volo carries a full aircraft parachute&lt;/a&gt;. On the other hand, many small engines and propellers certainly improve redundancy over conventional helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also have to wonder about the mass of the massive framework which is used to mount the rotors. It is in the way of the propeller flow and should contribute a substantial fraction to the empty mass of the e-volo. I expect the designers use it to store the battery cells, but I could not find much about this on the website - which offers, however, a &lt;a href=&quot;http://www.e-volo.com/konzeptstudien-2/actionvideo-vc007&quot; rel=&quot;nofollow noreferrer&quot;&gt;funny movie&lt;/a&gt; which nicely sums up the projected capabilities. Just don't get distracted while the e-volo waits for you in hover mode: The claimed flight time is currently only 20 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My verdict: It is less efficient than a comparable helicopter, but not by much. The two problems are the lower blade chord, which translates into more viscous friction, and the high mass and drag of the framework.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-11-11T14:33:08.087" LastActivityDate="2017-11-11T14:33:08.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16071" PostTypeId="1" CreationDate="2015-06-20T15:15:05.567" Score="7" ViewCount="1099" Body="&lt;ol&gt;&#xA;&lt;li&gt;Does the age of the aircraft increase the aircraft's maintenance expenses, fuel consumption, and electrical shorts?&lt;/li&gt;&#xA;&lt;li&gt;If so, by how much?&lt;/li&gt;&#xA;&lt;li&gt;And is this a reason why planes get scrapped?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="6967" LastEditorUserId="5517" LastEditDate="2015-07-23T18:19:40.030" LastActivityDate="2015-07-23T18:19:40.030" Title="Do older aircraft require increased general maintenance?" Tags="&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16072" PostTypeId="2" ParentId="16067" CreationDate="2015-06-20T15:33:09.967" Score="6" Body="&lt;p&gt;There is actually a simple answer, but it probably isn't exactly what you are looking for:  Refer all questions about what is allowed to your specific airline.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each airline has to come up with their own list of allowable electronic devices, and submit that list to the FAA with appropriate documentation in order to gain approval to allow passengers to use them during flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines allow almost everything as long as it can be put into a non transmitting mode (airplane mode), while some still require ALL electronic devices to be completely powered down at all points during the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of this, every airline is a little different and you are required to follow their rules while on their flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS receiver would not cause problems, but this doesn't mean that you are necessarily allowed to use it, and there are other things in your phone that could cause a problem though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, no electronic device that has a transmit function may be used because of possible interference though, unless specifically approved.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-06-21T10:46:37.860" LastActivityDate="2015-06-21T10:46:37.860" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16073" PostTypeId="1" AcceptedAnswerId="16075" CreationDate="2015-06-20T16:57:52.513" Score="5" ViewCount="2102" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;From a materials engineering standpoint, cockpit windshields,&#xA;  typically weighing between 25-40 pounds, depending on the type of&#xA;  windshield build, are typically constructed of several layers:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A glass face-plate, roughly 1/10&quot; thick;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) A Polyvinyl Butryal (PVB) layer, about 1/8&quot; thick;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) A stretched acrylic layer, approximately 1&quot; thick;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) An additional PVB layer, nearly 1/10&quot; thick;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) An additional stretched acrylic layer, approximately 1&quot; thick. &lt;a href=&quot;https://www.linkedin.com/pulse/20140507001219-90103575-cracked-aircraft-windshields-are-not-rare&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But even then, it is not unbreakable. We have had several cases of broken windshields, as mentioned in above source. Also, the co-pilot  in &lt;a href=&quot;https://en.wikipedia.org/wiki/Varig_Flight_254&quot; rel=&quot;nofollow noreferrer&quot;&gt;Varig Flight 254 crash&lt;/a&gt; was wounded from a tree, which struck his shoulder after crash landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, why are aircraft windshields not made from unbreakable &lt;a href=&quot;https://en.wikipedia.org/wiki/Glass-ceramic&quot; rel=&quot;nofollow noreferrer&quot;&gt;Glass Ceramics&lt;/a&gt; ?&#xA;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YBqgd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-23T07:22:29.530" LastActivityDate="2015-06-23T07:22:29.530" Title="Why are aircraft windshields not unbreakable?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16075" PostTypeId="2" ParentId="16073" CreationDate="2015-06-20T18:27:38.003" Score="15" Body="&lt;h2&gt;Windshields&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the US, aircraft windshields must conform to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.775&quot;&gt;14 CFR 25.775 - Windshields and windows&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Windshield panes directly in front of the pilots in the normal conduct of their duties, and the supporting structures for these panes, must withstand, without penetration, the impact of a four-pound bird when the velocity of the airplane (relative to the bird along the airplane's flight path) is equal to the value of V C, at sea level, selected under § 25.335(a).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, windshields are not indestructible partly because they are not required to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess windshields are not required to be indestructible because bodies like the FAA probably take the view that when an aircraft impacts a massive object at high speed, say a large mountain at 500 MPH, it is of no consequence whether the windshield survives intact at the bottom of a large crater of tiny aircraft fragments. It serves little purpose to make the windshield substantially stronger than the surrounding airframe.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Glass-Ceramics&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Glass Ceramics are not unbreakable. For example a glass-ceramic might have a bending strength of 340 MPa (&lt;a href=&quot;https://spiral.imperial.ac.uk/bitstream/10044/1/34/1/Glass-ceramics%20their%20production.pdf&quot;&gt;Ref p9&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-20T18:51:55.483" LastActivityDate="2015-06-20T18:51:55.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16076" PostTypeId="1" CreationDate="2015-06-20T19:48:27.480" Score="8" ViewCount="719" Body="&lt;p&gt;I understand that airline pilots are generally paid for their time &quot;in flight&quot;, which means the clock starts when the aircraft begins to move away from the gate. Are flight attendants paid in the same way?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-06-22T20:03:53.860" Title="Are flight attendants paid in the same way pilots are paid?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16078" PostTypeId="1" CreationDate="2015-06-21T08:28:02.360" Score="2" ViewCount="165" Body="&lt;p&gt;I know it's a bit off-topic but I guess some of the terminology used in the aircraft community is the same as in marine transportation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that both aircraft and marine vessels use fuel. But if I'm looking at the fuel prices on a commodities exchange, I guess the price is a bit different from the actual prices someone must pay for fuel used in the industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you have a name/term for fuel prices used in the industry, like fuel industrial price or something like that?&lt;/p&gt;&#xA;" OwnerUserId="8980" LastEditorUserId="65" LastEditDate="2015-06-22T13:58:33.073" LastActivityDate="2015-06-22T13:58:33.073" Title="Fuel price actually used in the industry" Tags="&lt;fuel&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2016-04-26T19:30:07.983" ContentLicense="CC BY-SA 3.0" />
  <row Id="16079" PostTypeId="2" ParentId="15843" CreationDate="2015-06-21T10:46:28.417" Score="1" Body="&lt;p&gt;Tight formation flying can be done with stock aircraft and skilled pilots, but drones would need additional sensors and new code in their &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot; rel=&quot;nofollow&quot;&gt;FCS&lt;/a&gt;. Also, you can fly aerobatics even with gliders, but only when a decent power-to-weight ratio is reached, aerobatics becomes a spectator sport. I think it is frivolous for the US Air Force to pay for the development and additional equipment to make drones fly aerobatic displays, but few Air Forces are known for an enlightened budget discipline. I expect, however, that this will be added first by a company producing drones, and for demonstration and marketing purposes, and then the taxpayer will fund this indirectly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Formation flying was a needed skill for bomber pilots, back then when their bundled defensive weapons provided the best protection against fighter attacks, and aerobatic flying was and still is valuable for fighter pilots. In the days of missiles and UAVs, neither formation flying nor aerobatics are necessary skills anymore, so in a way aerobatic formations are a quaint relic from the last millennium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To answer the &quot;could&quot; aspect of your question:&lt;/strong&gt; No, not directly. This would need modifications to existing drones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;To answer the &quot;ever&quot; aspect:&lt;/strong&gt; Once the services field UCAVs (unmanned combat drones) with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-45&quot; rel=&quot;nofollow&quot;&gt;good power-to-weight ratio&lt;/a&gt;, having them fly aerobatic displays looks almost unavoidable, but I expect it will not be the Air Force, but the marketing department of a big contractor driving this.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-06-21T10:46:28.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16080" PostTypeId="1" CreationDate="2015-06-21T10:59:26.137" Score="4" ViewCount="947" Body="&lt;p&gt;Some aircraft fuel tanks are fitted or retro-fitted with internal bladders, to prevent fuel evaporating inside the tank. I've heard of this being a requirement for at least one type, perhaps because of a poor fuel tank design, but how commonplace is it? How many aircraft have these bladders?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2019-03-04T09:10:53.137" Title="How prevalent are anti-explosion bladders in fuel tanks?" Tags="&lt;safety&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16081" PostTypeId="1" AcceptedAnswerId="16082" CreationDate="2015-06-21T11:46:41.223" Score="27" ViewCount="3963" Body="&lt;p&gt;I'm curious about how and where a stowaway could hide in the undercarriage of a plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.abc.net.au/news/2015-06-19/british-police-investigate-body-on-roof-suspected-to-be-stowaway/6560290&quot; rel=&quot;noreferrer&quot;&gt;this news report&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The man, believed aged 24, was found in the undercarriage of the&#xA;  plane and was taken to hospital.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="883" LastEditorUserId="65" LastEditDate="2015-06-22T14:03:45.860" LastActivityDate="2019-01-19T13:47:01.843" Title="How can a stowaway hide in the undercarriage?" Tags="&lt;passenger&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16082" PostTypeId="2" ParentId="16081" CreationDate="2015-06-21T11:55:38.233" Score="31" Body="&lt;p&gt;Wheel wells are deceptively large spaces when the gear is down. It is fully possible to climb up and hide inside one. It's a very different story when the gear is retracted. On many aircraft, the gear doors are  closed when the gear is not in motion, making the space look bigger. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are fairly easy to access through the landing gear with a little bit of climbing, or if low enough (like the example below) just jump up into. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-prn2/1502903_694459820584948_1188301230_o.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt; 737 Wheel Well, Petr Volek, from airliners.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A graphic about a similar event in Hawaii a few months ago:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YbgrY.jpg&quot; alt=&quot;graphic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt; From the &lt;a href=&quot;http://www.independent.co.uk/news/world/teenage-stowaway-survives-fivehour-flight-from-california-to-hawaii-by-hiding-in-jets-landing-gear-9273064.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Independent&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gear stowaways are not new and there have been plenty of occurrences over the years, unfortunately most result in fatalities.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Gear bays are unpressurized, hence normally very cold with air too thin  to sustain life. &lt;/li&gt;&#xA;&lt;li&gt;Gear bays are very cramped when the gear is up. If you're in the wrong spot, you will be injured.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is when the landing gear is lowered (and doors opened) for landing that the fatalities occur, assuming they have not already expired from the environment during the flight. Unable to hold onto the airframe and stay off moving parts they (very gruesomely) fall out minutes away from landing. This is also the story that media often picks up.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-01-19T13:47:01.843" LastActivityDate="2019-01-19T13:47:01.843" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16083" PostTypeId="2" ParentId="16076" CreationDate="2015-06-21T12:09:01.580" Score="7" Body="&lt;p&gt;It mightn't be a bad idea to specify which country you are talking about, as practices can vary throughout the world, and potentially even amongst individual airlines within the same country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last year I looked into becoming a FA for a smaller Australian airline. The pay arrangements were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A guaranteed minimum annual salary (which was about $45k)&lt;/li&gt;&#xA;&lt;li&gt;On top of that,  flying wages based on &lt;em&gt;scheduled&lt;/em&gt; flight times (4.20 per hour, a bit extra per hour for the hours worked above an agreed number of hours in a month). Note that even if a flight is delayed it is still issued with adjusted scheduled times. The 'padding' applied to regular scheduling works in favour for the employees here.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, I believe the US  works completely differently. And as I said, this is an example from only one airline. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-06-21T12:09:01.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16084" PostTypeId="2" ParentId="16059" CreationDate="2015-06-21T13:21:42.183" Score="6" Body="&lt;h2&gt;Power&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some models are different in power, a consideration if you intend to operate hot and/or high, or heavy. Otherwise that extra power is mostly fuel-inefficient.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Competition&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In situations where two or more alternatives are available, there's healthy competition. Engines are around 25% of the cost of a new aircraft, so there would be a big money to gain when airlines bulk order from a certain company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing took this a step further on the B787 where it's easier than ever to switch the type of engine to prevent this type of 'vendor lock-in'. Historically,  it was very difficult to switch due to the technical complexity in these systems.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Customer Relationship&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If an airline has good contacts with a manufacturer and know how they work, they may prefer to opt for that comfort when considerable money is on the line.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Part Commonality&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The more type of the same engine you operate, the better economies of scale you achieve. This is especially important as substantial maintenance work is concentrated around the engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This made for instance American Airlines store Boeing 757 aircraft that it got through a company acquisition that did not have the same engine type as the remaining fleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;ul&gt;&#xA;&lt;li&gt;This thinking is not limited to your company, but for instance within a group of companies, as heavy maintenance is often centralized.&lt;/li&gt;&#xA;&lt;li&gt;It can even apply across types. For instance, Korean Air ordered 787s and 747-8 both with GEnx engines. To quote GE Aviation on the two slightly different engine types: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The -2B contains an identical core and similar materials as the -1B, delivering synergies for mixed GEnx fleets&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-21T18:11:18.423" LastActivityDate="2015-06-21T18:11:18.423" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16085" PostTypeId="2" ParentId="16078" CreationDate="2015-06-21T18:17:50.403" Score="2" Body="&lt;p&gt;Jet Fuel is not listed on the commodities exchange, at least not according to &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_traded_commodities&quot; rel=&quot;nofollow&quot;&gt;this list.&lt;/a&gt; For what its worth small boats use regular car gas or diesel fuel and some larger ships are powered by &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_oil&quot; rel=&quot;nofollow&quot;&gt;fuel oil&lt;/a&gt; but they use boilers as opposed to a reciprocating engine like on smaller boats. Small boat gas tends to command a higher price because it can not because its any different than car gas. This is largely because you cant pull a big boat and take it to the gas station to fill it up every time you need fuel. AvGas for piston pounders is 110 or 100 octane low led. This is every similar to car gas (but higher octane and leaded). It is more expensive since it is taxed differently. Jet Fuel is effectively kerosene. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end of the day these are all crude oil byproducts so if you are looking for a commodity price the price of crude oil will effect the price of aviation fuels the same way it effects the price of car and boat fuels. Crude oil prices are about as close as you are going to get.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-21T18:17:50.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16086" PostTypeId="1" AcceptedAnswerId="16087" CreationDate="2015-06-21T18:32:40.410" Score="19" ViewCount="3904" Body="&lt;p&gt;My local airport has a Part 61 flight school and gives students the option of selecting among three Certified Flight Instructors. Farhan and others have posted &lt;a href=&quot;https://aviation.stackexchange.com/a/9870/8389&quot;&gt;excellent explanations&lt;/a&gt; of characteristics to look for in instructors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than wasted time and money, is there any downside to doing an &quot;Introduction to Flying&quot; lesson with each of the three instructors and seeing which one I like best? Similarly, am I likely to offend CFI's that I'm &quot;looking around&quot; other options?&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-26T18:31:20.617" Title="Is there a downside to trying multiple flight instructors?" Tags="&lt;flight-training&gt;&lt;flight-school&gt;&lt;cfi&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16087" PostTypeId="2" ParentId="16086" CreationDate="2015-06-21T19:09:39.543" Score="26" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;. Definitely try more than one CFI &lt;em&gt;and ideally, more than one school&lt;/em&gt;. This is the smart choice and one I recommended regularly when I was an active flight school CFI. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're about to spend a ton of money - do the due diligence and spend more up front to make sure you don't waste time and money with someone whose teaching style or personality clashes with you as a student. &lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-21T19:09:39.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16088" PostTypeId="2" ParentId="16086" CreationDate="2015-06-21T21:41:47.847" Score="12" Body="&lt;p&gt;As mentioned it's a good idea. You will be spending a lot of time with this person in a very confined space, not only should you trust their abilities but should at least get along with them. FWIW I would not consider this a waste of time as the hours will count towards your total and you will be learning new things while trying new instructors. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="2910" LastEditDate="2015-06-21T21:50:16.133" LastActivityDate="2015-06-21T21:50:16.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16090" PostTypeId="2" ParentId="16078" CreationDate="2015-06-21T22:21:18.183" Score="2" Body="&lt;p&gt;Oil/fuel trading is not really my field of expertise, but IATA provides an overview of jet fuel prices at &lt;a href=&quot;http://www.iata.org/publications/economics/fuel-monitor/Pages/price-analysis.aspx&quot; rel=&quot;nofollow&quot;&gt;their website&lt;/a&gt;. &#xA;They show the current average price for various parts of the world. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The data is sourced from &lt;a href=&quot;http://www.platts.com/jetfuel&quot; rel=&quot;nofollow&quot;&gt;Platts&lt;/a&gt;, an organisation that tracks many energy / petrochemical commodity prices.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-21T22:21:18.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16091" PostTypeId="1" AcceptedAnswerId="16093" CreationDate="2015-06-21T22:35:45.193" Score="5" ViewCount="1592" Body="&lt;p&gt;I'm looking for the lights and flashing patterns of the Airbus A340-313 (or any Airbus A340).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is related to this one: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9722/do-lights-on-aircraft-flash-in-a-specific-pattern&quot;&gt;Do lights on aircraft flash in a specific pattern?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but is very specific for this model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case I'll be grateful is there is some page or link with the patterns of several models (so I don't have to disturb you in the future :) )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance.&lt;/p&gt;&#xA;" OwnerUserId="8985" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-06-25T23:41:08.067" Title="What is the pattern of the flashing light in Airbus A340-300?" Tags="&lt;airbus&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16093" PostTypeId="2" ParentId="16091" CreationDate="2015-06-21T23:41:12.543" Score="3" Body="&lt;p&gt;For the lights on the A340-200/-300 see &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A340-200-300-20140101.pdf&quot; rel=&quot;nofollow&quot;&gt;Documentation&lt;/a&gt; page 129.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the lights on the A340-500/-600 see &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A340-500-600-20140101.pdf&quot; rel=&quot;nofollow&quot;&gt;Documentation&lt;/a&gt; page 133.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use the following link to see the lighting regulations for commercial aircraft -  &lt;a href=&quot;http://www.whelen.com/pb/Aviation/System%20Requirements/Anit-Collision%20Systems.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.whelen.com/pb/Aviation/System%20Requirements/Anit-Collision%20Systems.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Use of lights&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;AIM 4−3−23. Use of Aircraft Lights was updated in the latest edition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Guidance about using aircraft lights during ground operations also appears in AC91-73B, “Part 91 and Part 135 Single-Pilot Procedures during Taxi Operations.”&lt;/p&gt;&#xA;&#xA;&lt;p&gt;h. Use of Exterior Aircraft Lights to Make Aircraft More Conspicuous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) General. Exterior aircraft lights may be used to make an aircraft operating on the airport surface more conspicuous. Pilots may use various combinations of exterior lights to convey their location and intent to other pilots. Certain exterior lights may also be used in various combinations to signal whether the aircraft is on a taxiway or on a runway, in position on the runway but holding for takeoff clearance, crossing an active runway, or moving down the runway for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Because adherence to the guidelines in this AC are voluntary and aircraft equipment varies, pilots are cautioned not to rely solely on the status of an aircraft’s lights to determine the intentions of the pilot(s) of the other aircraft. Additionally, pilots must remember to comply with operating limitations on the aircraft’s lighting systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Exterior Lights. To the extent possible and consistent with aircraft equipage, operating limitations, and pilot procedures, pilots should illuminate exterior lights as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) Engines Running. Turn on the rotating beacon whenever an engine is running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(b) Taxiing. Prior to commencing taxi, turn on navigation, position, anti-collision, and logo lights, if available. To signal intent to other pilots, consider turning on the taxi light when the aircraft is moving or intending to move on the ground, and turning it off when stopped, yielding, or as a consideration to other pilots or ground personnel. Strobe lights should not be illuminated during taxi if they will adversely affect the vision of other pilots or ground personnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(c) Crossing a Runway. All exterior lights should be illuminated when crossing a runway.&#xA;CAUTION: Pilots should consider any adverse effects to safety that illuminating the forward facing lights will have on the vision of other pilots or ground personnel during runway crossings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(d) Entering the Departure Runway for Takeoff or LUAW. When entering a runway after being cleared for takeoff, or when taxiing into position and hold, pilots should make their aircraft more conspicuous to aircraft on final behind them and to ATC by turning on lights (except landing lights) that highlight the aircraft’s silhouette. Strobe lights should not be illuminated if they will adversely affect the vision of other pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(e) At Night, and When Cleared to LUAW. Consider lining up slightly (approximately 3 feet) to the left or right of the centerline (CL) to enable a landing aircraft to visually differentiate your aircraft from the runway lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(f) Takeoff. Landing lights should be turned on when takeoff clearance is received, or when commencing takeoff roll at an airport without an operating control tower.&lt;/p&gt;&#xA;" OwnerUserId="8967" LastEditorUserId="6" LastEditDate="2015-06-25T23:41:08.067" LastActivityDate="2015-06-25T23:41:08.067" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16094" PostTypeId="2" ParentId="16086" CreationDate="2015-06-22T00:09:31.063" Score="11" Body="&lt;p&gt;I think many instructors is a good idea, since you see their different&#xA;characteristics and each has their own sweet spot. I had at least&#xA;10 different instructors for my PPL, and learned a lot from the differences as&#xA;well as their similarities.&lt;/p&gt;&#xA;" OwnerUserId="3212" LastEditorUserId="8887" LastEditDate="2015-10-26T18:31:20.617" LastActivityDate="2015-10-26T18:31:20.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16095" PostTypeId="1" CreationDate="2015-06-22T00:49:17.823" Score="5" ViewCount="8113" Body="&lt;p&gt;How many flight training hours can a student realistically do in a week? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have 11 PIC flight hours (and solo'd at 7hrs) but I havent flown (PIC time) since 2008. I want to finally get my license but am unsure if I can realistically do it before I leave the country in one month. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In one week, I can actually devote my entire day to flight training so I'm wondering how many PIC flight hours a student can realistically do in one day and thus a week. &lt;strong&gt;Is 2-3hrs flight time (2-3 actual sorties) for 7 days realistic?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I know this is highly dependent on my CFI but let's assume I can find one to match my speed...&lt;/p&gt;&#xA;" OwnerUserId="8986" LastActivityDate="2015-06-22T17:40:53.047" Title="How many flight training hours can a student realistically do in a week?" Tags="&lt;flight-training&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16096" PostTypeId="2" ParentId="16095" CreationDate="2015-06-22T01:41:42.807" Score="4" Body="&lt;p&gt;There are a few external factors &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Your CFI:&lt;br&gt;&#xA;If we are talking about dual time (or supervised solos) here your CFI will need to be free. &lt;/li&gt;&#xA;&lt;li&gt;The plane:&lt;br&gt;&#xA;Keep in mind that school may have other students who may also book the plane, or it may be out for its 100 hour inspection or it is broken etc. &lt;/li&gt;&#xA;&lt;li&gt;The weather:&lt;br&gt;&#xA;Depending on where you are located, you may be limited by the weather grounding you for VFR flight.&lt;/li&gt;&#xA;&lt;li&gt;The Wind:&#xA;A lot of flight schools (at least the one I go to) impose student maximum limits when it comes to crosswinds. At single runway airports this could cause an issue. You can mitigate this by training at a place with two runways.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now if we look past all those and assume you have a working plane, a CFI, and clear weather, then I would think (assuming the school is open) you could log 3 hours in the morning and 3 in the afternoon if you really pushed it. If you started your day with 1 hour of ground from 8-9 then flew from 9-noon. Lunch. Then another hour of ground from 1-2 and flying from 2-5 that is putting you at close to 6 hours a day. Throw a few night flights in there, some more ground lessons at night and you may be able to squeeze the time in. Keep in mind you will also need to study for the written exam.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note:&lt;/em&gt; The above projection is strictly based on everything working all the time which in aviation is often not the case. Your results may vary.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-22T14:25:10.037" LastActivityDate="2015-06-22T14:25:10.037" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16097" PostTypeId="2" ParentId="15140" CreationDate="2015-06-22T02:31:40.020" Score="1" Body="&lt;p&gt;I cannot find Mike Foxtrot's answer so this might be duplication. The power consumed is the power used by each lamp multiplied by the number of lamps. Every type of aircraft is likely to have its own type of lamp &amp;amp; its own number of lamps. Also, cabin lamps can be dimmed &amp;amp; reading lamps are a variable load.&#xA;LEDs are getting more powerful (light output/energy consumed) so fewer lamps are needed, but this comes at the price of more heat generated; this requires heatsinks. So the designer will select lamps on the basis of light output, area to be illuminated, power consumption, heat output &amp;amp; heatsink size.&#xA;So a definitive answer to your question could only apply to one type of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8967" LastActivityDate="2015-06-22T02:31:40.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16098" PostTypeId="1" AcceptedAnswerId="16124" CreationDate="2015-06-22T05:30:17.303" Score="8" ViewCount="11434" Body="&lt;p&gt;Some Air forces (Like the Indian Air force) do not allow Color Blind pilots. Is this local only to the IAF or a global procedure? Also, are there any regulations regarding commercial pilots not being Color Blind?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="7532" LastEditDate="2015-06-23T03:57:00.227" LastActivityDate="2015-07-23T21:46:38.680" Title="Why do some Air Forces not allow Color Blind Pilots?" Tags="&lt;pilots&gt;&lt;medical&gt;&lt;indian-air-force&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16099" PostTypeId="1" AcceptedAnswerId="16123" CreationDate="2015-06-22T05:38:14.367" Score="7" ViewCount="1349" Body="&lt;p&gt;I recently read a question about Anti Explosion fuel tanks which are self sealing. But the technology seemed to be too old after a bit of research, and that it was difficult to apply this age old technique to pressurized fuel tanks at high altitudes. What are the modern technologies being used for auto - sealing of fuel tanks after being hit by enemy fire to avoid detonation?&lt;/p&gt;&#xA;" OwnerUserId="8814" LastEditorUserId="19" LastEditDate="2016-07-28T11:32:40.630" LastActivityDate="2016-07-28T11:32:40.630" Title="What is the working principle of anti-explosion fuel tanks?" Tags="&lt;aircraft-design&gt;&lt;accidents&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16100" PostTypeId="1" AcceptedAnswerId="16105" CreationDate="2015-06-22T06:11:23.447" Score="23" ViewCount="12377" Body="&lt;p&gt;It is very common today for planes to land on snow (for example, in Antarctica). How are planes kept in control with so little friction against the ground? What is the procedure to perform this kind of landing? How much extra distance, on average, does an aircraft cover by landing on snow, compared to landing on dry pavement? (&lt;a href=&quot;https://www.youtube.com/watch?v=QocqjS5Mjik&quot; rel=&quot;noreferrer&quot;&gt;Video&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ETSNz.jpg&quot; alt=&quot;4 US Air Force Hercules aircraft at Willies field, Antarctica&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4 US Air Force Hercules aircraft at Willies field, Antarctica &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Aircraft_in_Antarctica.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8667" LastEditDate="2015-06-22T19:10:17.833" LastActivityDate="2015-06-22T20:23:16.427" Title="How do aircraft land on snow?" Tags="&lt;landing&gt;&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16102" PostTypeId="2" ParentId="16100" CreationDate="2015-06-22T06:26:11.713" Score="8" Body="&lt;p&gt;I'd quote from this &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/7298/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Landing on snow itself is not a problem. The rudder is used for steering upon landing so control is no different than landing on a dry runway.&lt;/p&gt;&#xA;&lt;p&gt;Getting stopped is where it can get alittle tricky. Careful use of reverse thrust and braking along with not making any turnoffs from the runway until sufficiently slowed are the name of the game.&lt;/p&gt;&#xA;&lt;p&gt;A wise Capt once told me not to make any turns offs from a snowy/slippery runway until your slow enough that you have to actually add power to get off. Wise advice indeed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Landing on wet or contaminated runways requires more&#xA;close control over approach speeds.&#xA;With a B747 you should accomplish touchdown on the&#xA;runway at 1.000 ft from the approach end of the runway. The airplane should be flown firmly onto the&#xA;runway at the aiming point. It's very important not to land long! The speedbrakes should be used immediately&#xA;after the main gear contacts the runway, because they&#xA;destroy lift, increase drag and, most important, increase&#xA;main gear loading. It's necessary to use thrust reversers at high power as soon as possible because&#xA;they are most effective at high speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Hope this answers your questions. TY&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-22T06:26:11.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16105" PostTypeId="2" ParentId="16100" CreationDate="2015-06-22T06:44:34.077" Score="24" Body="&lt;p&gt;It is very common for planes to land on snow (i.e. &lt;em&gt;packed&lt;/em&gt; snow) or even ice runways.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How are planes kept in control with so less friction on ground?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Snow/ice friction is a function of the outside air temperature, so it depends. Another factor is whether the runway was packed, fresh snow - and the temperature the previous day. The colder it is, the more friction the snow will have (i.e. adequate braking). In warmer temperatures the snow will be slick (scarily slick at times - as in nil braking).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While flying a multi-engine airplane, one can use differential power. If you're flying a single-engine airplane - one is better off with small taps on the brake during slick conditions. If the OAT is relatively cold (well below freezing), braking can be pretty good.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the procedure to perform such kind of landing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The procedure is the same as a standard landing. However, it is awfully nice to have good contrast on the snow to see the runway. Often runways that are pure snow/ice will be more visible than the surrounding terrain. At the very least - the runway will be outlined with some sort of runway markers.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And, on an average how much extra distance does an aircraft &#xA;  covers by landing on snow, as compared to landing on ground?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As I said before, it is really dependent upon the outside air temperature and the condition of the runway (i.e. packed snow or fresh snow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, suppose there were fresh snow on a relatively warm day (30 degrees farenheight) and the snow is compacted (i.e. by humans) that day. Say, night-time temperatues drop to 0F, and the next day you land with an OAT of 30 to 35+F... that runway is going to be SLICK. However, if the temperatures were to stay at 0F - you would actually have decent braking. Even further, if the OAT dropped to -40 below...you will have excellent braking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TLDR&lt;/strong&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Snow conditions are always changing and braking/control of the airplane are dependent on those conditions. Snow-conditions are highly dependent on the outside air temperature and to some degree human-maintenance (for better or worse).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*source: Personal experience from flying in the Arctic.&lt;/p&gt;&#xA;" OwnerUserId="553" LastEditorUserId="-1" LastEditDate="2015-06-22T13:24:10.297" LastActivityDate="2015-06-22T13:24:10.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16106" PostTypeId="2" ParentId="16086" CreationDate="2015-06-22T06:51:11.780" Score="17" Body="&lt;p&gt;My first flight instructor was kind of a jerk.  You know the kind: First flight, &quot;Let's take the plane for a SPIN&quot;, &quot;How about a BREAKFAST ROLL?&quot;  After a few hours into my training, there was a scheduling conflict and I got a different instructor - a military pilot with many thousands of hours of flying time and a very different attitude. Professional. He worked me harder than the other instructor ever had. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight school eventually canned my first instructor.  He moved across the field and took on new students at a different school.  Then there was the day one of his students almost ran over me in the pattern.  They were flying a Cessna and I was flying a Grumman.  The tower had cleared them AFTER me, but they apparently never even saw me and pulled into the pattern on the downwind right underneath me.  Fortunately, both I and the tower realized what was happening, so I just maintained altitude and extended the downwind leg and the tower cleared the Cessna ahead of me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I called up the flight instructor to tell him about the near mishap, his attitude was quite cavalier.  He seemed to think it was funny.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shop around.  If you can find a military instructor with thousands of hours of flight time, odds are you'll find a very serious teacher.&lt;/p&gt;&#xA;" OwnerUserId="8992" LastActivityDate="2015-06-22T06:51:11.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16108" PostTypeId="1" AcceptedAnswerId="16117" CreationDate="2015-06-22T08:17:15.947" Score="24" ViewCount="5083" Body="&lt;p&gt;According to the wikipedia page : &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Air vortices can form around the main rotor of a helicopter, causing a dangerous condition known as vortex ring state (VRS) or &quot;settling with power&quot;. In this condition, air that moves down through the rotor turns outward, then up, inward, and then down through the rotor again. This re-circulation of flow can negate much of the lifting force and cause a catastrophic loss of altitude. Applying more power (increasing collective pitch) serves to further accelerate the down wash through which the main-rotor is descending, exacerbating the condition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The vortex ring state has also been listed as a potential hazard in the Wikipedia &lt;a href=&quot;https://en.wikipedia.org/?title=Helicopter&quot;&gt;page&lt;/a&gt; for helicopters. What are the various preventive measures used to prevent such a condition?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2020-01-28T19:24:36.293" Title="How do modern helicopters tackle Vortex Ring State?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;helicopter&gt;&lt;vortex-ring-state&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16109" PostTypeId="5" CreationDate="2015-06-22T08:18:55.507" Score="0" Body="&lt;p&gt;A vortex ring, also called a toroidal vortex, is a torus shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortex rings are plentiful in turbulent flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the smoke rings which are often produced intentionally or accidentally by smokers. Fiery vortex rings are also a commonly produced trick by fire eaters. Visible vortex rings can also be formed by the firing of certain artillery, in mushroom clouds, and in microbursts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A vortex ring usually tends to move in a direction that is perpendicular to the plane of the ring and such that the inner edge of the ring moves faster forward than the outer edge. Within a stationary body of fluid, a vortex ring can travel for relatively long distance, carrying the spinning fluid with it.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:10:11.700" LastActivityDate="2015-06-23T11:10:11.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16110" PostTypeId="4" CreationDate="2015-06-22T08:18:55.507" Score="0" Body="A vortex ring, also called a toroidal vortex, is a torus shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:08:06.503" LastActivityDate="2015-06-23T11:08:06.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16111" PostTypeId="2" ParentId="16108" CreationDate="2015-06-22T08:25:51.293" Score="27" Body="&lt;p&gt;Helicopter driver here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not aware of any technical features which can prevent it.  Quite simply, the disc must accelerate air downwards to generate lift.  If the helicopter descends into that downward accelerating air, it is recycled through the disc resulting in a catastrophic loss of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The preventative measures are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Be aware of the flight conditions under which vortex ring state may occur.&lt;/li&gt;&#xA;&lt;li&gt;Do not fly into these conditions.&lt;/li&gt;&#xA;&lt;li&gt;Be able to recongise the symptoms of vortex ring state.&lt;/li&gt;&#xA;&lt;li&gt;Understand, and be practised in, the correct recovery technique, which is most often fly in any direction away from the vortex.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I am not an aerodynamics engineer but I doubt that there is a physical solution to this - and if there was, it would likely have been implemented by now.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-09-29T05:35:50.217" LastActivityDate="2016-09-29T05:35:50.217" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16112" PostTypeId="1" AcceptedAnswerId="16115" CreationDate="2015-06-22T08:29:06.270" Score="21" ViewCount="13476" Body="&lt;p&gt;I am an aviation enthusiast. A couple of months back I came to know about the difference between piloting Boeing and Airbus planes here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/149/what-are-the-main-differences-piloting-boeing-vs-airbus-aircraft&quot;&gt;What are the main differences piloting Boeing vs. Airbus aircraft?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The very first comparison says this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boeing trusts more the pilots: they can supersede the autopilots&#xA;  commands by exerting enough force on the controls&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Airbus trusts more the autopilot: if the system is fully functional it&#xA;  will always have priority over the pilots (but they still have room&#xA;  for &quot;non-standard&quot; maneuvers, e.g. commanding bank angles beteween 33°&#xA;  and 60°)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also another answer stated this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus aircraft limit pilots' capabilities in situations that require&#xA;  extreme action to be taken; the computer may prevent the pilot from&#xA;  pushing the plane past its safe ranges, which could be necessary in&#xA;  case of an emergency.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Boeing aircraft leave ultimate control mostly to the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now relating the above points with the recent near vertical take off by Boeing 787-9 in the Paris air show 2015:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eax6x.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this near vertical take off is an example that &quot;Boeing aircraft leave ultimate control mostly to the pilot&quot;? If Airbus aircraft trust the autopilot more, would they allow this type of takeoff as it is done by pilot by pushing the engines to extreme? Also, is it some kind of mockery by Boeing to Airbus?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For those who haven't yet watched the video, here is the link:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/KYbM-3E11Qo?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="863" LastEditorUserId="863" LastEditDate="2019-07-01T14:34:05.907" LastActivityDate="2019-07-01T14:34:05.907" Title="Could the Boeing 787-9 near vertical takeoff demonstration be performed by Airbus A350 aircraft?" Tags="&lt;takeoff&gt;&lt;airbus&gt;&lt;boeing&gt;&lt;boeing-787&gt;&lt;airbus-a350&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16113" PostTypeId="1" CreationDate="2015-06-22T09:06:38.830" Score="6" ViewCount="581" Body="&lt;p&gt;I have seen many photos with those sensors attached to the test aircraft, Can you provide why they are used and what do they measure? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/EeYOW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is another example on SuperJet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uFLsK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8960" LastEditDate="2015-06-22T14:02:36.670" LastActivityDate="2015-06-22T14:47:03.027" Title="Can you identify those parts (sensors), on test aircraft and the purpose?" Tags="&lt;flight-instruments&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16115" PostTypeId="2" ParentId="16112" CreationDate="2015-06-22T09:20:33.723" Score="40" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, as a comment noted, the takeoff was hardly &quot;near vertical&quot;, the camera angle makes it look so. The takeoff angle in the video certainly is much steeper than a normal one, but Airbus aircraft are more than capable of doing the same - in fact an A350 did &lt;a href=&quot;http://www.irishtimes.com/news/technology/paris-air-show-airbus-a350-xwb-performs-near-vertical-take-off-1.2249934&quot;&gt;very much the same thing&lt;/a&gt; at the Paris Air Show. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The notion that an Airbus doesn't let the pilots have complete control is a little bit misleading. I'm not going to go into too much detail in this question, but what most people are referring to when they say that is the Alpha Protection system. This system kicks in when the aircraft is at extreme angles of attack. For example, if an aircraft is about to stall, it will not let the pilot pull the nose up. In any plausible situation the pilot would not want to raise the nose anyway, yet we have seen accidents such as &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Colgan_Air_Flight_3407&quot;&gt;Colgan 3407&lt;/a&gt; where the pilot did exactly that (and, also &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;AF447&lt;/a&gt;, however the system was disabled in that crash). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, the Airbus system pretty much only prevents pilot actions that are dangerous (OK it is more complex than that, and the Boeing design has benefits too, but..). Back to your question, why does the Airbus system also allow such a steep takeoff? Because only the attitude was high, but the angle of attack was still within normal limits. These takeoffs are possible on lightly loaded aircraft with engines near full power.   &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-06-22T09:20:33.723" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16116" PostTypeId="1" CreationDate="2015-06-22T10:10:48.130" Score="9" ViewCount="913" Body="&lt;p&gt;Propeller-powered aircraft have a &quot;problem&quot; called &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow noreferrer&quot;&gt;P-Factor&lt;/a&gt;, where the descending blade of the prop is generating more lift (a.k.a. thrust) then the ascending blade due to a higher angle of attack when the angle of attack of the wings is high. (I hope I summed that up properly.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about helicopters? For this example let's say the blades turn counterclockwise when seen from the top.  When the helicopter is accelerated, the blades on the right side of the helicopter are faster then the ones on the left side.  Thus they should be generating more lift. The higher the speed, the higher the difference in lift on both sides would be. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What mechanism handles corrections that have to be made due to this lift difference? How does it work?&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="62" LastEditDate="2017-03-22T13:15:58.467" LastActivityDate="2017-03-22T20:24:19.013" Title="How do helicopters handle P-Factor?" Tags="&lt;helicopter&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16117" PostTypeId="2" ParentId="16108" CreationDate="2015-06-22T10:58:57.987" Score="10" Body="&lt;p&gt;There's an interesting article on the hazards at &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_ring_state&quot;&gt;wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The avoidance tactic mentioned in that article is to avoid rapid descents at low forward airspeed - this would seem sensible as that's where the rotors will be exposed to their own downwash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the preferred reaction also described there is to use the cyclic to fly forwards, to move into less disturbed air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I have heard that another cause of the condition is flying into narrow spaces among tall buildings, but unfortunately I haven't been able to find a reference.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-06-22T10:58:57.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16118" PostTypeId="2" ParentId="16071" CreationDate="2015-06-22T13:33:07.610" Score="4" Body="&lt;p&gt;The very simple answer to your first question is just &lt;strong&gt;&lt;em&gt;yes&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As something (or someone) age, more maintenance is required. It varies from case to case and you cannot have &lt;em&gt;one size fits all&lt;/em&gt; rule or guideline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA has published a thorough &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/design_approvals/small_airplanes/cos/aging_aircraft/media/aging_aircraft_best_practices.pdf&quot; rel=&quot;nofollow&quot;&gt;guide for maintaining older airplanes (PDF)&lt;/a&gt;. For the relation of age on maintenance costs, &lt;a href=&quot;https://www.cna.org/sites/default/files/research/D0000289.A2.pdf&quot; rel=&quot;nofollow&quot;&gt;this article (PDF)&lt;/a&gt; discusses it in detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting to your last question, it also depends on an individual case. Please also note that when an airplane is &lt;em&gt;grounded&lt;/em&gt;, it is not required to be scrapped in all cases. Sometimes museums are interested in it, or it can be installed as a &lt;a href=&quot;http://i109.photobucket.com/albums/n63/sasroodkapje/off-b25-cocha-mp01.jpg&quot; rel=&quot;nofollow&quot;&gt;roadside monument&lt;/a&gt; or placed in an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_boneyard&quot; rel=&quot;nofollow&quot;&gt;aircraft boneyard&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding when an aircraft needs to be retired or scraped, these two articles are a good read:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.conklindd.com/t-whentoreplaceanaircraft.aspx&quot; rel=&quot;nofollow&quot;&gt;When to replace an aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.conklindd.com/t-howoldistooold.aspx&quot; rel=&quot;nofollow&quot;&gt;How old is too old?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-22T13:33:07.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16120" PostTypeId="2" ParentId="16113" CreationDate="2015-06-22T14:47:03.027" Score="2" Body="&lt;p&gt;On the super jet that's a pitot tube rather large but still it's a testing aircraft. Aircraft's use pitot tubes to measure airspeed. The example, from an Airbus A380, combines a pitot tube (right) with a static port and an angle-of-attack vane (left). Air-flow is right to left. A pitot (/ˈpiːtoʊ/ PEE-toh) tube is a pressure measurement instrument used to measure fluid flow velocity. And so on, The basic pitot tube consists of a tube pointing directly into the fluid flow. As this tube contains fluid, a pressure can be measured; the moving fluid is brought to rest (stagnates) as there is no outlet to allow flow to continue. This pressure is the stagnation pressure of the fluid, also known as the total pressure or (particularly in aviation) the pitot pressure. Go &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot_tube&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, for evidence.&lt;/p&gt;&#xA;" OwnerUserId="8960" LastActivityDate="2015-06-22T14:47:03.027" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16121" PostTypeId="1" AcceptedAnswerId="16122" CreationDate="2015-06-22T15:10:15.080" Score="9" ViewCount="5583" Body="&lt;p&gt;While reading up on the Boeing C-17 Globemaster III, I came across a reference to its maintenance man-hours which surprised me. As listed in the &lt;a href=&quot;http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104523/c-17-globemaster-iii.aspx&quot;&gt;spec sheet&lt;/a&gt; (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These requirements include an aircraft mission completion success probability rate of 92 percent, &lt;strong&gt;only 20 aircraft maintenance man-hours per flying hour&lt;/strong&gt;, and full and partial mission availability rates of 74.7 and 82.5 percent, respectively. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now this strikes me as a rather steep maintenance requirement, especially considering the spec lists &quot;only 20 hours&quot;. If I understand that statement correctly, for every hour spent in flight, 20 technicians have to spend that same amount of time maintaining the plane after landing. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do those 20 hours refer to an average over extended operation of the aircraft? In other words, does this include extended maintenance where the plane might be undergoing days of intensive maintenance, skewing the numbers?&lt;/li&gt;&#xA;&lt;li&gt;Is this a low number for this class of aircraft?&lt;/li&gt;&#xA;&lt;li&gt;Do the required maintenance hours scale with: size, complexity, military/commercial use?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8585" LastEditorUserId="19" LastEditDate="2016-07-14T08:40:45.523" LastActivityDate="2016-07-14T08:40:45.523" Title="How should the number of maintenance hours per flight hour for the C-17 be interpreted?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16122" PostTypeId="2" ParentId="16121" CreationDate="2015-06-22T15:39:49.483" Score="5" Body="&lt;p&gt;I am sure the raw data can be found somewhere in some document or budget line item but there are a few things to keep in mind. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;These numbers may only be airframe maintenance preformed. According to &lt;a href=&quot;http://www.dodbuzz.com/2015/02/17/pratt-whitney-subpoenaed-on-c-17-engine-maintenance/&quot;&gt;this article&lt;/a&gt; it seems that P&amp;amp;W maintains the engines. &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://aviationweek.com/awin/looking-house-maintenance-support&quot;&gt;This article (a bit dated)&lt;/a&gt; states that the air force must only maintain 50% of the work in house. Again they may only be counting their hours. &lt;/li&gt;&#xA;&lt;li&gt;The air force (and all military aircraft) are subject to their own regulations and intervals and such. Although they must play by FAA rules when flying in airspace their upkeep is to the standards set forth by the owning military body. This may make it hard to compare with general aviation or commercial aviation.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do the required maintenance hours scale with: size, complexity, military/commercial use?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general yes. A piper cub is going to be simpler to maintain per hour than say an F-16 but as you know things vary. I would say that the hours scale more with complexity than size. Mainly because from a mechanical stand point a more complex engine or aircraft would have more things to disassemble and go wrong and in turn more things to put back together generally increasing maintenance time. Keep in mind this is a very general statement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of military vs commercial use, you will see a lot more maintenance on a military fighter than a commercial plane largely as a result of design. Commercial planes have lots of redundant systems and reliable parts as they are selling safety. Fighters have lots of high performance parts, some redundancy and things that may be made to wear faster in order to preform. Again a general statement but you can get the gist. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do those 20 hours refer to an average over extended operation of the aircraft? In other words, does this include extended maintenance where the plane might be undergoing days of intensive maintenance, skewing the numbers?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Im going to assume that this is an overall average but it may not be. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-22T15:39:49.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16123" PostTypeId="2" ParentId="16099" CreationDate="2015-06-22T17:02:16.413" Score="9" Body="&lt;p&gt;Modern military fuel tanks use the same basic technology to seal the tank after a puncture as WW2 aircraft did, which is the use of a laminated rubber-textile material, which tends to retain its form after being torn. The main difference between modern tank liners and WW2 liners is that the modern liners use more sophisticated materials so they can achieve the same benefit using a much thinner liner (hence less weight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bullets hitting a tank do not cause &quot;detonation&quot; unless they generate a spark and the fuel-air mixture in the tank is in ignition range. Also, most aircraft explosions are not detonations, they are &lt;a href=&quot;https://en.wikipedia.org/wiki/Deflagration&quot;&gt;deflagarations&lt;/a&gt;. The liner does nothing to prevent this. The main functions of the liner are to prevent fuel from leaking out of a punctured tank and to maintain the integrity of the tank in a low-altitude mishap or crash. The main test for a liner is the &quot;drop test&quot; in which the liner is filled with fuel and dropped from a height of about 50 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage of pressurizing a tank with air (inerting) is that it increases the critical temperature of an explosive mixture. If the critical temperature of the mixture is above the ambient temperature, then the tank will not explode spontaneously when sparked. A modern variation on this is called &quot;nitrogen inerting&quot;. The idea with that is to pressurize the tank with nitrogen. This makes the tank spark proof.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that inerting technologies do not prevent a fuel tank from blowing up if an aircraft is hit with ordnance. The reason for this is that typically the way an aircraft blows up is that damage from the ordnance starts a fire. The fire then rapidly evolves fuel-laden gases into open compartments of the aircraft. As soon as these gases reach the ignition mixture, the fire deflagarates the mixture, causing an explosion. Inerting does little to prevent this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inerting is very useful, however, because it can prevent a plane blowing up due to lightning or problems with electrical wiring or static electicity buildup.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="511" LastEditDate="2015-06-22T17:07:59.277" LastActivityDate="2015-06-22T17:07:59.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16124" PostTypeId="2" ParentId="16098" CreationDate="2015-06-22T17:12:21.570" Score="15" Body="&lt;p&gt;In fact, most militaries don't take colorblind people into flight school.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Colorblindness can be a serious problem for a pilot, because in the interest of cost and/or simplicity, not all indicators in an aircraft cockpit are colorblind-accessible. It's really cheap to use a two-way red/green LED as a status indicator (and by quickly alternating the current through the LED you get amber); it's much more expensive in electro-mechanical systems to combine text and color so that the status can be deciphered by someone who is red-green colorblind. It becomes easier again in a glass cockpit, but that increases cost and there are still concerns like screen resolution to consider when designing text-and-color displays. While it's in the general interest of aviation manufacturers to design certain avionics with as many overlapping visual cues as possible, it's not always feasible to specifically design towards colorblind accessibility in every circumstance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a set of spectra simulating how various forms of colorblindness would change a person's perception of the normal color set:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WQXHS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WQXHS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Protanopia and deuteranopia are various forms of red-green colorblindness, the most common form of dichromia (protanopia is a deficiency in red cells, deuteranopia a deficiency in green; the results are similar because red and green are close in wavelength). Tritanopia is commonly called blue-yellow colorblindness and is less common, with full colorblindness (monochromia) being very rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this chart, we can deduce the following basic difficulties for a red-green colorblind person attempting to operate a plane:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Red on brown, or any dark color, would have no contrast. That would make reading (and setting) this Cessna radio stack nearly impossible:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZWn2O.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZWn2O.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... as well as decreasing the contrast of red lines on high-elevation sectionals (like Charlie/Echo space boundaries, non-towered airports, NDB frequencies etc):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Nn134.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nn134.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Green and yellow are practically indistinguishable. That would make discerning the borders of inhabited low-lying areas on sectionals difficult:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j7Mkf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j7Mkf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... as well as making the color-coding of this airspeed gauge much less useful at a glance:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6aDWA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6aDWA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Blue and magenta are indistinguishable, as are cyan and white. That makes your GPS useless over water; where's the magenta line?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DURKc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DURKc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While you could probably get around most of these difficulties (buy a nav stack with blue LED displays, trace the borders of your sectional charts in something, configure the GPS to give you a white line, etc etc) these are all images that people with full color vision would be able to discern at a glance, which in an emergency situation is often a life-or-death advantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That point is especially true for military pilots, who are typically subject to more rigorous medical screening and training including very high requirements for visual acuity (often better than 20/20 uncorrected vision). If you can't see extremely well in a combat situation, you will either fail to spot an enemy until he has gained a significant advantage over you, or you will fire on friendly forces; either way, you're a liability. Coupled with the fact that everyone and their brother grew up dreaming of being a fighter pilot, flight schools get to be picky. Therefore, military aircraft cockpits are typically designed with the assumption of full color spectrum perception, because the only people who will ever be in them will be able to tell red from green, blue from yellow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider, just as one example, a hypothetical conflict in the Middle East involving the Turks and Iranians, where NATO and thus the USAF is also involved. Both of these countries still operate variants of the F-4 Phantom. With an ROE requiring visual confirmation of a hostile, if you are in a USAF F-22, in a visual-range tangle with an F-4 whose IFF is inconclusive (either non-functioning or malfunctioning) and you can't tell the difference between these two rondels...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RvEhx.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9byPI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... you are screwed. The fact the Phantom is maneuvering against you is what any pilot would do when approached by an aggressor aircraft; a Turkish pilot isn't just going to sit there and be shot down by friendly fire, he'll engage defensive, so you can either shoot and risk spending the rest of your life in Leavenworth for dereliction of duty, or break engagement, presenting your tailpipe to the other craft and hoping it's not hostile. Fifty-fifty shot either way with a hundred and fifty million dollar plane on the line, not to mention your life. Your first clue it's an Iranian would be a missile launch, and no matter how much more advanced USAF craft are now than in the era of the F-4, an aircraft that has successfully launched a short-range missile at you has you by the wrinkly ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, ground lighting systems are often not differentiable either. For instance, there is an important difference between a heliport beacon flashing green-yellow-white versus white-green-red (the one including a red flash is a hospital helipad and off-limits to gen-av traffic even in an emergency), but a red-green colorblind person may well not be able to tell the difference. Runway end lights are either green or red, indicating traffic direction (though there's usually a secondary cue of the approach array lights sequencing toward or away from the runway edge). Similarly, to a person for whom red is indistinguishable from white, the red-over-white glide slope indicator at the end of the runway would be useless (this would typically happen only with full colorblindness). Blue-yellow colorblindness is the other major type of partial colorblindness, and it would cause other problems like decreasing readability of navigation charts (for instance, incorporated land areas are yellow on FAA sectionals, while Victor routes and class B/D airspace borders are different blues) and trouble negotiating taxiways as the blue taxiway lights would look the same as yellow-white indicator lights elsewhere on the tarmac.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T21:46:38.680" LastActivityDate="2015-07-23T21:46:38.680" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16125" PostTypeId="1" AcceptedAnswerId="16139" CreationDate="2015-06-22T17:13:46.007" Score="12" ViewCount="15769" Body="&lt;p&gt;Planes can sometimes be seen &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_advertising#Fixed-wing_aircraft&quot;&gt;towing banners&lt;/a&gt; around large cities or events. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is the banner attached for takeoff?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the plane land after towing a banner?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="572" LastEditDate="2015-06-24T07:15:13.887" LastActivityDate="2015-06-24T07:15:13.887" Title="How does banner tow attach and release work?" Tags="&lt;general-aviation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16126" PostTypeId="2" ParentId="16098" CreationDate="2015-06-22T17:16:35.713" Score="6" Body="&lt;p&gt;In the United States, military pilots must have full color vision. We have something like 100 applicants for every 1 position, so there is no question of accepting pilots who have vision problems. Military pilots are expected to have flawless vision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vision, including color vision, is very important for all pilots, not just military pilots. Flying requires picking out tiny lights of different colors from long distances away. I remember the first time I did night flying, boy was that hard. You would fly towards a city with literally millions of lights surrounded by complete blackness and the instructor would say, &quot;Where's the airport?&quot; You have to visually pick out a tiny little white and green light from a long distance away out of millions of other lights. Red and green lights are very common. For example, the nav lights on aircraft are red and green. If you could not tell the difference, you might not be able to tell if another aircraft is coming towards you or moving away from you. There would be many other problems as well.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-22T17:16:35.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16127" PostTypeId="2" ParentId="16125" CreationDate="2015-06-22T17:31:05.320" Score="6" Body="&lt;p&gt;The basic procedure goes like this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A flying airplane with a tow hitch mounted to its tail, which acts as the attache point for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Grapple_(tool)&quot;&gt;grapple hook/cable&lt;/a&gt; &lt;em&gt;and&lt;/em&gt; the release mechanism.&lt;/li&gt;&#xA;&lt;li&gt;Those grapple cables are attached to the tow hitch, and runs up the side of the airplane. The hook is hanging in the door and the cable is tied off on the strut, so that it has an easy to release knot. There can be multiple grapple hooks.&lt;/li&gt;&#xA;&lt;li&gt;The pilot grabs the hook, pulls it to untie the knot, and throws the hook out and back.&lt;/li&gt;&#xA;&lt;li&gt;After the banner is picked up and the flight, the pilot release the grapple hook and cable from the tow hitch by using lever which is mounted in the cockpit. The process can start over again.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This can be seen in &lt;a href=&quot;https://youtu.be/ufXXU6ur9Ac&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;https://youtu.be/N9pdWFlvQec&quot;&gt;this&lt;/a&gt; videos.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-22T17:31:05.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16128" PostTypeId="2" ParentId="16086" CreationDate="2015-06-22T17:37:03.717" Score="3" Body="&lt;p&gt;There is no harm trying out different instructors. Note that instructors have different strengths. Some may be better at teaching tailwheel and others at instruments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One problem is that you will not really be able to tell the difference between a good instructor and a better one in one flight, unless it is a personality issue. From a technical point of view it will be hard to tell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Better instructors tend to get booked up and are hard to schedule. If your instructor's schedule looks really full, that is a good sign he is a good one. Also, look at their flying experience. I notice that the better instructors tend to have more flight hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you start flying be sure to get &quot;check rides&quot; from other instructors once in a while. Different instructors have completely different styles and areas of emphasis, so it can be very useful to get &quot;alternative points of view&quot; from time to time. A new instructor will usually teach you new stuff. In this sense, even a bad instructor can be good sometimes because they can teach things maybe your usual instructor does not know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beware of &quot;easy&quot; instructors that just soft shoe everything. They are the nicest instructors, but they are slow teachers and they can be derelict and just &quot;go with the flow&quot; when they should be correcting you. If one or two instructors tell you that you should not fly and are not cut out to be a pilot, the dumbest thing you can do is to find an easy instructor who will just collect your money, even though he knows you are not pilot material.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-22T17:37:03.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16129" PostTypeId="2" ParentId="16095" CreationDate="2015-06-22T17:40:53.047" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is 2-3hrs flight time (2-3 actual sorties) for 7 days realistic?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think that's do-able.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical flight lesson is about 1.0-1.5 hours of &quot;flight time&quot;, with a pre-brief and post-brief to go over the lesson. If you do 2-3 of those you'll be in the air somewhere between 2 and 5 hours, and spend another 1-2 hours on the ground. Add in time for lunch and stretching your legs between flights and you've filled an 8 hour day with training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How effective that training will be is a different story.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I did a lot of &quot;double header&quot; days when I was wrapping up my training: I would go up with my instructor in the morning, have lunch, then come back and solo for an hour or so working on the stuff I needed to work on.&lt;br&gt;&#xA;I think that was an effective way to finish up (because I was working on specific targeted things).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you're effectively a &quot;post-solo&quot; student I think you'll fall into this box: Spend a day or two with an instructor getting the rust off your skills and getting signed off to solo again, knock out your cross-country and night requirements if you don't have them already, and then split your remaining time between flights with your instructor doing checkride prep &amp;amp; solos working out the kinks.&lt;br&gt;&#xA;2-4 hours in the air and as much classroom &amp;amp; study time as it takes might get you there - if not you can continue the training in your spare time (before/after work or whatever other activities are tying you up for the rest of the month).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember you'll also need to find an examiner to give you your checkride, so plan for that (sometimes they're booked out pretty far in advance).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The flip side of the coin is that I also did a few &quot;double-header&quot; days early on in my training (pre-solo), where my instructor and I would book a 4 hour block and spend 2.5-3 hours in the air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extra time in the air was fun (it was enough time to go visit other airports), but in retrospect I don't think it was anywhere near as effective pre-solo as it was post-solo: When you're first learning to fly 1-2 hours in the air each day is about all your brain can handle (at least it was all &lt;strong&gt;&lt;em&gt;my&lt;/em&gt;&lt;/strong&gt; brain could handle), and then you need to take the time to digest what you learned, read over the lesson materials, and let the knowledge soak into your head. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-06-22T17:40:53.047" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16130" PostTypeId="1" AcceptedAnswerId="16135" CreationDate="2015-06-22T18:21:43.173" Score="5" ViewCount="1774" Body="&lt;p&gt;What were to happen if deicing fluid went in to an engine. I have heard that deicing fluid is somewhat flammable. What were to happen if it went in to the engine? Would it combust like fuel?&lt;/p&gt;&#xA;" OwnerUserId="8960" LastEditorUserId="679" LastEditDate="2015-06-22T19:20:18.693" LastActivityDate="2015-06-23T03:06:46.107" Title="What were to happen if deicing fluid went in to the jet-engine?" Tags="&lt;jet-engine&gt;&lt;anti-ice&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16131" PostTypeId="2" ParentId="16071" CreationDate="2015-06-22T18:29:54.867" Score="2" Body="&lt;p&gt;Short answer; yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with any complex mechanical system, there are several overlapping service lives of various subsystems. Simply put, the longer a machine is in operation, the more wear and tear is put on parts of the machine that aren't designed to wear out and be replaced as part of normal maintenance (like brake pads, belts, hoses, etc). You replace your car's tires every 30k-60k miles, but the drivers' side door isn't something you just plan to replace after X miles. Nevertheless, replacing or refurbishing the driver's side door after 20 years will probably give you a noticeable improvement with regards to all the things that door contains, from the hinges it opens on to the gasket that seals it against rain and noise, to all the switches, motors and servos controlling the window, lock, mirror, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true for an airplane; the longer the airframe is in service, the more things that aren't designed to wear out do so anyway. The difference is that with a car, if a wheel falls off or the radiator hose blows out, you just limp to the side of the road and call a tow truck. Failures on an aircraft are not so easily handled, and remember the mantra; taking off is optional, landing is mandatory. By the same token, while car maintenance is frequently stretched far more than is prudent, because the gamble is against an inconvenience of a few hours and the tow truck fee, maintenance on an aircraft is a no-nonsense business because the gamble of not doing it is the lives of a hundred-plus people aboard when something goes wrong; inspections with accompanying repairs, replacements and retrofits happen at set intervals of flight hours or press/depress cycles, like clockwork, without fail, or the plane doesn't fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means the longer the airframe is in service, the more things start to reach the point where they must be replaced, either because they've worn out or are obsolete. Eventually, between the cost of replacement and the lost revenue of the plane being out of service to fix the ever-increasing number of failing components, it's no longer good business to continue operating that particular airframe, at which point it's sold, either in flyable condition to a discount airline, or for parts/scrap at a boneyard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, newer planes have a lot of advantages simply because they were developed using better technology. Engines, for instance, are a component of a plane that is not easily upgraded to an entirely new design, because of considerations like overall aerodynamics and under-wing clearance. While some upgrades are possible (the 737-100 had a much smaller, less efficient engine than modern 700s and 800s), they're expensive to apply especially to a fleet of hundreds of planes, and they often involve tradeoffs like reducing cargo area or increasing pilot workload due to less integration capability of the new system with existing avionics. As a result, turnover of an airline's fleet is a virtual necessity to continually improve the fleet's performance as well as avoid end-of-life mechanical problems.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T17:26:20.173" LastActivityDate="2015-07-23T17:26:20.173" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16132" PostTypeId="1" AcceptedAnswerId="16136" CreationDate="2015-06-22T18:48:02.170" Score="4" ViewCount="553" Body="&lt;p&gt;I've been looking for places to rent planes in the Caribbean, and haven't been able to find anything that wasn't charter service. Does anyone know of any pilot resources or specific rental or flight schools in the Caribbean, specifically the southern Caribbean? &lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="19" LastEditDate="2016-11-01T11:57:51.557" LastActivityDate="2016-11-01T11:57:51.557" Title="What are the options for renting an aircraft in the Caribbean with an FAA certificate?" Tags="&lt;general-aviation&gt;&lt;rental&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16133" PostTypeId="2" ParentId="16112" CreationDate="2015-06-22T18:51:20.413" Score="3" Body="&lt;p&gt;Paris Air Show was quite funny for that: you could see pilots the A350 and on the 787 take off as early and as steeply as possible. I remember seeing the pilot of the 787 progressively take off several meters earlier (possibly something like 20m).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, this video was &lt;em&gt;not&lt;/em&gt; at Paris Air Show but somewhere near Seattle as far as I know. The ground is nothing like Paris nor near Paris nor continental France. It was also posted to youtube the day after the first take off of the 787 before this year's Paris Air Show: no way they had managed to make a proper video in only a few hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also important to keep in mind the planes are really empty when they do that: even the A380 manages to fare very well for such things. Now, add 600 people with luggage for a total weight of at least 100kg each (60 tonnes total) and add kerosene too: it'll be entirely different.&lt;/p&gt;&#xA;" OwnerUserId="9002" LastEditorUserId="556" LastEditDate="2018-03-08T22:43:23.453" LastActivityDate="2018-03-08T22:43:23.453" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16134" PostTypeId="2" ParentId="16130" CreationDate="2015-06-22T18:51:30.940" Score="2" Body="&lt;p&gt;It would not explode it would combust.    It would combust at a different rate from jet fuel but unless it was at large quantities (like in the fuel not just sucked off the plane) it should not cause any problems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combustion is oxidation and is limited by mass transfer delivering the oxidizing element (oxygen).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an explosion all the components are in molecular close proximity and the rate is only limited by kinetics.   A bomb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alcohol is kind of in between as oxidation liberates oxygen but it is still mass transfer limited.&lt;/p&gt;&#xA;" OwnerUserId="8649" LastActivityDate="2015-06-22T18:51:30.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16135" PostTypeId="2" ParentId="16130" CreationDate="2015-06-22T19:09:19.220" Score="3" Body="&lt;p&gt;Alcohols are typically very effective de-icers (consider that ordinary vodka won't freeze until -17*C, and ethylene glycol, a &quot;diol&quot; or &quot;double alcohol&quot; with two hydroxyl groups, is used as an antifreeze in automotive coolant), but virtually all of them are flammable in some concentration, so it could affect the engine, but unless the engine drew straight deicer through the fuel line it would be unlikely to cause a major problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, it would depend on exactly which deicing compound is being used; the most common are methanol, ethylene glycol, propylene glycol and glycerin. These all have different flash points and different heats of combustion (the amount of energy released by burning them) which will differ more or less dramatically from those of 100LL or Jet A. The closer a compound is in its combustion characteristics to that of the actual fuel, the more it will act like the fuel and thus the fewer problems you'll have; ideally, a compound that is indistinguishable from the aircraft's fuel will simply result in a richer mixture if it's ingested through the air intake (which can be easily corrected with the mixture knob), while if it's fed through the fuel line you'll see no difference at all in the short term (in the long term the de-icer might cause more buildup of combustion byproducts inside the engine requiring cleaning).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a difference in combustion characteristics, you'll see a difference in engine performance relative to the amount being ingested by the engine. A lower flash point for the de-icer means it will ignite before the fuel does and can cause misfires in the engine which is bad (the timescale for exactly how bad depends on the severity and timing of the misfires and the type of engine). A higher flashpoint will cause the engine to lose power, as the de-icer won't burn as efficiently in the combustion chamber, and if ingested through the air intake, will displace oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;De-icer mixed with water is probably the worst case scenario, as under no circumstances will fuel, de-icer and water all sit in a homogeneous solution. Again it depends on how much the engine gets, but the addition of water will act to quench combustion and can cause an engine failure that you're unlikely to recover from in the air (once water gets into an engine it's very difficult to get it back out).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a jet engine, most of these considerations are reduced by the simple fact that as much as 80% of the air entering the nacelle never enters the actual combustion chamber. So, ground crews at major airports can be much more liberal with de-icer around engine intakes (and should be, as the pressure differentials inherent in and around a jet intake can increase ice crystal formation). Further, commercial jet engines have to be rated to withstand ridiculous amounts of ingested materials of all kinds, including water, birds, dust/sand, etc. A little de-icer is probably the friendliest foreign substance to be introduced into a passenger jet's turbofans during its service life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, a simple search for &quot;anti-ice&quot; turns up several variants of aviation and automotive fuel with de-icing components mixed in; it's especially important for automotive fuel as most of these fuels contain ethanol which is hygroscopic (it will pull water out of the air) causing ethanol-water ice crystals to form in the fuel lines. AvGas is an older formulation that still uses tetraethyllead and no ethanol, but water contamination is still possible and so a fuel stabilizer (which also typically acts as a deicer) is a common addition to winter fuel tanks. So, aircraft manufacturers know that de-icer will be fed into the engines in some way or other, and they design those engines to be tolerant of it.     &lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="524" LastEditDate="2015-06-22T20:43:41.380" LastActivityDate="2015-06-22T20:43:41.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16136" PostTypeId="2" ParentId="16132" CreationDate="2015-06-22T19:32:43.373" Score="5" Body="&lt;p&gt;You would be much better off renting the plane in the United States. It will be difficult to find a rental anywhere in the Caribbean, except maybe Puerto Rico.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may want to read Greenspun's &lt;a href=&quot;http://philip.greenspun.com/flying/caribbean&quot; rel=&quot;noreferrer&quot;&gt;Flying in the Caribbean&lt;/a&gt;. It's a little dated but has good information.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-22T19:32:43.373" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16137" PostTypeId="2" ParentId="16071" CreationDate="2015-06-22T19:33:04.760" Score="3" Body="&lt;p&gt;Farhan poses some great points and offers some great articles but for the sake of the other side of the answer I will offer up some other points mainly related to GA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the general answer is yes, I will offer an answer that &quot;Hours are more important than years&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a pure engineering standpoint wear and tear is more a &lt;a href=&quot;https://en.wikipedia.org/wiki/Wear&quot; rel=&quot;nofollow&quot;&gt;function of cycles&lt;/a&gt; than time. An new aircraft that is used as say a trainer and sees lots of hours a year may be in worse shape than a privately owned rarely flown aircraft from 30 years ago. To you points,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;fuel consumption (and oil consumption for that matter)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Both more a function of the engine than the airframe. Engines are overhauled in and around 2000 hours for GA planes (or if there is an incident or problem). A freshly overhauled engine will (or at least should) preform like a brand new engine and should burn oil and fuel as such. Depending on how often you fly there are plenty of very old planes out there with low hour overhauled engines that run like a top.    &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;maintenance expenses&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general yes older planes will cost more to keep up as they may see more broken parts due to use. On the other hand older planes tend to be simpler and parts are often cheaper. One could argue its cheaper to upkeep an older Piper Arrow than a brand new Cirrus (granted these are very different planes). But the Cirrus sees a very pricy annual as a result of its ballistic chute and I'm sure the carbon fiber is not cheap to fix if something goes wrong. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another point to note and this very much depends on the plane but lets break GA aircraft into 2 categories. All metal (or composite) and fabric/wood planes. It should be obvious that fabric covered planes are not as durable as their metal counterparts and can be harder to leave outside in weather which means you will need a hangar. Wood planes or planes with wood components (early Mooney's) suffer from rot and cracked wood. Then again metal planes can suffer from rust and corrosion. You may also be hard pressed to find a mechanic who knows the ins and outs of a wood plane these days. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sweet spot seems to be the early but not first all metal planes (think Piper Cherokee). These planes are simple and easy to fix, contain parts that are still made in many cases making them cheap to own. You can buy a beat up 140 for the price of a composite 3 blade prop for some of these new planes. Granted you won't go nearly as fast, you will still fly and you will still own a plane.     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2015-07-23T17:40:18.690" LastActivityDate="2015-07-23T17:40:18.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16138" PostTypeId="2" ParentId="16067" CreationDate="2015-06-22T19:39:56.280" Score="2" Body="&lt;p&gt;The simplest answer to your question is, none that have not been specifically approved for use by the FAA. The FAA, in U.S.-controlled airspace, has pretty much all the power and responsibility for ensuring civilian air travel is safe, and they operate with an abundance of caution in all things, because that draconian code of rules and regulations is what keeps the agency itself from taking blame for a plane crash; if everyone followed all the rules and the plane still went down, it's the government's butt on the line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the FAA has, for decades, maintained more or less a blanket ban on operation of devices with a transmit feature, even as modern airframes (and by &quot;modern&quot; I mean practically anything in the sky today) are well-shielded against radio interference, and consumer devices available for purchase and casual use do not transmit on frequencies anywhere near those used by aircraft for communication or navigation. The reason is simply that it is possible for a device to cause interference with aircraft systems, whether directly by pirating the frequency or indirectly through intermodulation or other artifacts of radio carrier wave dynamics, and it was simpler, easier and cheaper at the time for the FAA to ban them all than to evaluate every device or device type against every airframe in commercial aviation, verify empirically that it does not cause interference, and educate flight crews and the general public about which device types, makes and models specifically are or are not allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has since changed tack; it has worked with the FCC beginning in the 90s to develop a set of joint rules for both device and aircraft systems design that, if complied with by the manufacturers, will guarantee the device will not cause interference. Devices meeting these criteria, including practically any smartphone or tablet on the market today, can be used during &quot;non-critical&quot; stages of flight (all usage of potentially-interfering devices is still restricted during takeoff, landing or at any time by instruction of the flight crew) while onboard an aircraft certified for use of such devices while airborne (meaning the airframe complies with rules for shielding/isolation of sensitive electronics; this certification, including any needed retrofits, can be done during scheduled maintenance on each airframe).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-26T20:57:06.203" LastActivityDate="2015-06-26T20:57:06.203" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16139" PostTypeId="2" ParentId="16125" CreationDate="2015-06-22T20:02:05.803" Score="18" Body="&lt;p&gt;There are actually a couple of different towing mechanisms out there. You've got your traditional banner pick, with the ropes and the hooks and all that, but there's also a new type of billboard mechanism that allows a tow aircraft to take off with the billboard already attached; it unfurls as the aircraft gains altitude, and can eliminate a potential inefficiency in the process (some days are worse for banner picks than others due to high winds, turbulence, etc.), but it limits the tow aircraft to some pretty small billboards and letter banners are pretty much a no-go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Talking about the traditional method of banner towing, there are a couple of things to cover.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The banner/billboard setup on the ground - they will be attached to a tow rope (usually about 200 feet long) with a loop at the end. This loop is strung out between two poles a small distance apart. The goal of a banner pick is to have the hook pass between the poles, thru the loop; do that and you will be able to pick the banner off the ground. The banner or billboard will be laid down upwind of the poles (with the tow rope fully extended), so that the pick takes place into the wind; the lower ground speed will help with timing and allow the banner or billboard to come off the ground more smoothly. A small windsock is a common addition next to the poles to make it easier for the pilot to spot them and to give some local wind information. The banners and billboards may be set up parallel to a runway (usually the active runway), or there may be a designated spot elsewhere on the field.&lt;/li&gt;&#xA;&lt;li&gt;The hook itself is attached to aircraft with a tow hitch and it is possible to have multiple hitches on the same aircraft (highest number i ever saw was 4 on a Piper Pawnee); they get used sequentially i.e. drop the hook, pick up the banner, fly the banner, drop the banner, drop the next hook, pick up the next banner, fly said banner, and so on until you run out of hooks. Most of the time, hooks that are not in use will be tied down somewhere accessible to the pilot who will drop them manually. That Pawnee I mentioned earlier, however, had the hooks attached to hitches on the aircraft's belly, from where they would be released with a switch, so there's more than one way to skin a cat. The hooks are normally attached prior to engine start and the pilot needs to make sure there is no slack in the line, to avoid it becoming entangled in rudder or elevator cables (more on that later), or other assorted bits and pieces of equipment.&lt;/li&gt;&#xA;&lt;li&gt;Banner tow procedures&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Take off is normal, but depending on your hook and cockpit setup, you may have to hold the hook in your throttle hand as you're taking off (this was the case with the Husky I towed in). Be careful not to hit anything with it.&lt;/li&gt;&#xA;&lt;li&gt;After climbing through about 50 feet AGL, side-step the runway, and drop the hook. Procedure varies depending on your setup, but we used to extend the arm holding the hook as far out the window as we could get, give a gentle tap on the rudder to kick the tail out of the way and toss the hook outwards and away from the airplane. Kicking the rudder was important due to the way the rudder control cables ran in the Husky; we had one pilot who didn't and nearly wrecked when the rope got fouled around the cables, forcing a rudder hard-over once there was tension in the line after the pick - fortunately he was a big guy and the runway was sufficiently long that he was able to overpower the rudder and make a safe landing. Tossing the hook outwards is important lest it get caught up in the propwash and bang against the skin of the aircraft. Again, this happened (wasn't me though).&lt;/li&gt;&#xA;&lt;li&gt;Coming around for the banner pick - depending on where the banners are set up, you may end up flying almost a regular traffic pattern, but it usually happens at much lower altitudes (5-600 feet) and the banner tow waiver may require that you avoid flying over populated areas to do so, so you may end up flying, say a right-hand pattern instead of your regular left. Either way you end up doing it, you want to end up downwind of the poles, similarly, if you will, to coming in for landing.&lt;/li&gt;&#xA;&lt;li&gt;The actual banner pick - this is where you'll see a lot of variation. Some outfits will come in flat, just above the poles and pull up once they pass them (unusual, but some do it that way), others will come in high and dive towards the poles, and pull up once past them (it's very pretty and dramatic, but not a lot of room for error IMO). We used to be a bit more sedate about it, and came in as if for a landing, with the goal of touching down at the top of the banner (i.e. the end nearest to you). Obviously, you have to correct for crosswind, which you can do by shifting your line left or right depending on wind direction; the goal is to place the hook, which is trailing behind you and getting blown about by the wind, between the poles. Either way you do it, once you pass the poles, you pitch up immediately to at least 45 degrees or so, and apply full throttle. You zoom climb to about 200 feet AGL and then reduce the pitch angle to be able to maintain a slow-speed climb. Do this right and the banner or billboard will come smoothly off the ground; you may feel a slight tug as tension is applied through the towline if you haven't been smooth enough and ended up yanking the banner off the ground. Continue to climb to whichever altitude you've planned for and, when stabilized in the climb, try to take a look behind you (if you can) to make sure you've picked successfully and that the banner didn't get damaged or something. If you can't look behind you, you can check during a turn, or have your ground crew radio/text and let you know.&lt;/li&gt;&#xA;&lt;li&gt;Fly the banner - you want to fly slow enough to avoid stressing the engine, airframe, tow rope and banner, but not quite so slow that the engine can't get enough airflow to cool down (remember, on the backside of the power curve, power required increases the slower you try to fly). Watch your altitude and distance from people and objects (the powers that be are quite serious about it), look out for towers (especially those that come with guide cables and the like), high rise buildings, and other traffic, and try not to get too bored flying in circles for hours.&lt;/li&gt;&#xA;&lt;li&gt;Drop the banner - when you come back in to drop the banner, the goal is to drop it low enough to the ground that the wind won't have time to blow it away onto  active runways (or into the trees - I had to help pull somebody else's banner out of the trees once, not fun). Ideally, you might want to drop it as close as you can to where the ground crew has their bags and everything setup to spare them having to haul heavy banners and billboards over long distances. You release the hook using a lever bolted onto the floor of the aircraft and then apply power, climb out, and come around for another pick or a landing, whatever the case may be.&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Hope this helps, let me know if you'd like to know more about any of this.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastEditorUserId="7568" LastEditDate="2015-06-22T20:52:41.953" LastActivityDate="2015-06-22T20:52:41.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16140" PostTypeId="2" ParentId="16076" CreationDate="2015-06-22T20:03:53.860" Score="1" Body="&lt;p&gt;It really all depends on the airline and their CBAs with various unions. Practically every major job role you encounter while taking a plane trip is represented in the U.S. by a different trade union; there's a pilot's union (several actually, biggest is the ALPA but some major carriers like AA and USAir have their own), a flight attendants' union (AFPA and AFA-CWA plus some carrier-specific affiliates), a mechanics' union (AMA and AMFA), a ground crew's union (mainly AFL-CIO or TWU), a baggage handlers' union (also either TWU or AFL-CIO but it can differ from the one for maintenance crews), an ATC union (NATCA), and even the TSA screeners are now unionized through the American Federation of Government Employees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these unions negotiate more or less independently with the airlines on many things, including pay structure. It's often a matter of who gets there first when there are rumors of increased airline profits; on one airline the flight attendants might be treated like gold while the pilots are making peanuts and pushed right up against FAA regs on working hours and conditions, while the exact opposite may be true just one gate down. Exactly how they're compensated is usually public information since the airlines themselves are publicly traded and this information is part of their cost structure, but it is more likely to be different between airlines than the same, especially for a major U.S. carrier whose flight crews are represented by company-specific unions.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-22T20:03:53.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16141" PostTypeId="1" CreationDate="2015-06-22T20:09:50.367" Score="2" ViewCount="884" Body="&lt;p&gt;I have heard it said on several occassion that when you are landing you need to control your descent with your throttle, and not with your &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_principal_axes#Lateral_axis_.28pitch.29&quot; rel=&quot;nofollow&quot;&gt;pitch&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two closely related questions that I think can be answered in one go:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why do we use throttle instead of pitch to control the descent?&lt;/li&gt;&#xA;&lt;li&gt;How does this work in practical terms?  (How do you do it?)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1467" LastEditDate="2015-06-23T13:11:44.203" LastActivityDate="2015-06-23T13:11:44.203" Title="What is meant by &quot;Control your descent with throttle when landing, not with pitch&quot;" Tags="&lt;landing&gt;&lt;airspeed&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-06-22T20:14:00.357" ContentLicense="CC BY-SA 3.0" />
  <row Id="16142" PostTypeId="2" ParentId="16141" CreationDate="2015-06-22T20:12:13.720" Score="3" Body="&lt;p&gt;Your pitch is adjusted to maintain airspeed, whereas throttle and thrust are used to establish a rate of descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shameless steal from &lt;a href=&quot;https://aviation.stackexchange.com/users/7629/keiths&quot;&gt;KeithS&lt;/a&gt; comment below:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Y]ou're gliding down to the runway, but you need a little engine power to keep a shallow glide slope because you aren't in an actual glider. The real explanation is that trying to use pitch to control glide slope causes dramatic changes in angle of attack, especially at the lower speeds used for approach and landing. This could cause a stall, or a severe loss of altitude. The throttle provides much more minute control over your angle of attack and thus your glide slope. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-06-23T12:43:22.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16143" PostTypeId="2" ParentId="16100" CreationDate="2015-06-22T20:23:16.427" Score="4" Body="&lt;p&gt;I only fly single engine aircraft.  I have landed a number of time on snow and on ice.  The two things I do differently is to 1) feather the touch-down with a slight power increase just before hand, and 2) &quot;fly&quot; the aircraft all the way to a near stop.  That is to say that instead of steering the plane once on the ground, you treat it more like you are still in the air.&lt;/p&gt;&#xA;" OwnerUserId="9003" LastActivityDate="2015-06-22T20:23:16.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16144" PostTypeId="1" AcceptedAnswerId="16146" CreationDate="2015-06-22T22:22:22.817" Score="4" ViewCount="3114" Body="&lt;p&gt;When I look at Inner Thames Estuary Airport (Isle of Grain) &lt;a href=&quot;https://www.tfl.gov.uk/cdn/static/cms/documents/isle-of-grain-master-plan.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;masterplan&lt;/a&gt;, they shows a funny figure about the terminals layout.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/nNz92.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report describes that  &lt;strong&gt;&lt;em&gt;It shows the ability for most&#xA;stands to handle either a large wide bodied (Code E/F) aircraft or two narrow bodied (Code C) aircraft.&lt;/em&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, is it true?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-06-22T22:54:15.237" LastActivityDate="2015-06-23T01:17:56.877" Title="Does the size of code F aircraft parking apron enough for 2 code C plane?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16145" PostTypeId="1" CreationDate="2015-06-23T01:17:33.087" Score="6" ViewCount="673" Body="&lt;p&gt;Why is Mi-35M so huge in size? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the benefit of having an attack helicopter to be so big?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is no benefit, why wasn't its size reduced?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apache is not as huge as this.&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorDisplayName="user8792" LastEditDate="2015-06-23T04:54:08.243" LastActivityDate="2015-06-23T05:17:03.277" Title="Why is Mi-35M so huge in size?" Tags="&lt;military&gt;&lt;helicopter&gt;&lt;russia&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-06-27T03:33:29.770" ContentLicense="CC BY-SA 3.0" />
  <row Id="16146" PostTypeId="2" ParentId="16144" CreationDate="2015-06-23T01:17:56.877" Score="5" Body="&lt;p&gt;This type of parking system is called MARS (Multi Aircraft (or Apron) Ramp System) and is being used or explored by many airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see markings for them on the ground at CLE.  Here is a google maps link to one of the stand areas.  &lt;a href=&quot;https://www.google.com/maps/place/41%C2%B024&amp;#39;42.4%22N+81%C2%B050&amp;#39;27.5%22W/@41.411785,-81.840977,232m/data=!3m2!1e3!4b1!4m2!3m1!1s0x0:0x0&quot;&gt;CLE terminal&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airportsinternational.com/2013/02/manoeuvres-on-mars/13873&quot;&gt;Here&lt;/a&gt; is an article on the stands.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastActivityDate="2015-06-23T01:17:56.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16147" PostTypeId="1" CreationDate="2015-06-23T01:20:32.033" Score="0" ViewCount="1015" Body="&lt;p&gt;When Canadians realized that it was a mistake to abandon their jet fighter program, why didn't they revive it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why wasn't Avro Arrow program revived ever?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastActivityDate="2015-07-10T17:46:40.017" Title="Why wasn't Avro Arrow program revived ever?" Tags="&lt;fighter&gt;&lt;canada&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-06-23T13:16:45.703" ContentLicense="CC BY-SA 3.0" />
  <row Id="16149" PostTypeId="2" ParentId="16130" CreationDate="2015-06-23T03:06:46.107" Score="4" Body="&lt;p&gt;Deicing fluid is inhaled by jet engines nearly every time the truck is called out. The question is how much deice can the engines tolerate? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbine engines can accept a rather staggering amount of water, to the point that testing them becomes an exercise in water handling instead of engine handling. The fire department can empty their trucks into an idling engine and not affect it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deice does contain various flammable liquids, but the overall mixture is not flammable - rather dangerous although fire would be a quick way to clear the ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, unless you find a way to empty the truck into the engine in less than a few seconds it's simply not an issue.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-23T03:06:46.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16150" PostTypeId="1" AcceptedAnswerId="16155" CreationDate="2015-06-23T03:14:17.190" Score="16" ViewCount="8564" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727&quot;&gt;Boeing 727&lt;/a&gt;, put into service in 1963, had the distinction of a rear doorway with stairs that could be lowered so that passengers could embark and disembark at rural airports which did not have their own airstairs.  As initially designed, this door could be opened even whilst in flight as it is not the usual &quot;plug&quot; style.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1971, the hijacker known as &lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper&quot;&gt;DB Cooper&lt;/a&gt; famously used the rear door to make his parachute escape mid-flight. According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727#Operational_history&quot;&gt;wikipedia&lt;/a&gt;, the CIA also used this feature to drop passengers and supplies mid-flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9koSW.gif&quot; alt=&quot;727 ejecting DB Cooper&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the wake of the DB Cooper incident and other hijackings, the FAA mandated in 1972 that &lt;a href=&quot;https://en.wikipedia.org/wiki/Cooper_vane&quot;&gt;cooper vanes&lt;/a&gt; to be installed to prevent the opening of the rear door while in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this make the pre-cooper 727 the last passenger airliner which had a door (either passenger or cargo) that could be normally opened while in flight without depressurizing the entire cabin? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Small Print: There was a rear cabin, pressurized bulkhead door on the 727 that you had to transit through to get access to the ventral stairways which was in the aft, unpressurized bulkhead. The actual ventral stair door itself was not a &quot;plug&quot; style. Thus the ventral stairways meets the requirement of being able to open in flight (even if you couldn't get there because the rear cabin bulkhead door might not open). &lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Animated image from wikipedia and cc.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="65" LastEditDate="2015-06-23T18:32:12.200" LastActivityDate="2019-07-10T17:18:46.267" Title="Was the 727 the last airliner whose doors could be opened in flight?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16151" PostTypeId="1" AcceptedAnswerId="16158" CreationDate="2015-06-23T03:34:40.597" Score="18" ViewCount="6005" Body="&lt;p&gt;In reading through the more informal literature (Wikipedia, FAA PDFs, Av.SE), I often come across a caveat to standard flight rules and procedures: &quot;unless an emergency exists&quot;. The intention is obvious; ATC is going to prioritize helping an aircraft that encounters a situation that simply cannot be ignored. However, most such resources don't go into specifics about what kind of situations constitute an &quot;emergency&quot;. There are obvious emergency scenarios, like a &quot;dead stick&quot;, and there are obvious non-emergencies like &quot;I have to be on the ground by 5:00 to beat traffic home&quot;. Then there are grey areas like &quot;I fought a headwind the whole way here, I'm low on gas and now my home field is IFR and won't grant me SVFR. I &lt;em&gt;might&lt;/em&gt; make it to my alternate even further upwind that's clear, but I &lt;em&gt;really&lt;/em&gt; think it's best to set down here even if I can't see the far end of the runway&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What kinds of things constitute a genuine emergency, and what will get a pilot laughed at by ATC (or worse)? Where's the line?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is ATC allowed to judge what is or is not an &lt;em&gt;actual&lt;/em&gt; emergency, or must they prioritize any aircraft declaring one?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does fault or blame matter at the time the emergency is declared? Will ATC de-prioritize a situation that is obviously the pilot's fault, like flying into the only cloud for 50 miles in any direction?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there anything you still can't do as PIC in an emergency situation? Apparently in an emergency you can do a lot of things that would get your license pulled in any other scenario, like violating separation minimums, entering airspace that's normally off-limits like R-zones and Class A space, running on instruments without a rating, etc. While these things are still dangerous, it is apparently the pilot's prerogative to resolve the emergency however he can. Is there anything a plane declaring an emergency still must do other than fly the plane, or conversely something he still cannot do like get too close to Air Force One?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;After declaring an emergency in flight, what should be done after the plane's back on the ground (hopefully safely)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2018-07-02T21:58:14.447" Title="What constitutes an &quot;emergency&quot; in flight procedures?" Tags="&lt;emergency&gt;&lt;flight-training&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16154" PostTypeId="2" ParentId="16145" CreationDate="2015-06-23T05:17:03.277" Score="5" Body="&lt;p&gt;Apache is pure attack helicopter with just two crew. Hind is a mixed role attack and light transport helicopter with additional room for 8 troops. Different role, different size.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-23T05:17:03.277" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16155" PostTypeId="2" ParentId="16150" CreationDate="2015-06-23T05:57:45.543" Score="14" Body="&lt;p&gt;The door of an airplane can be opened in any of the aircraft only when the airplane is depressurized. When an airplane is pressurized, the extra pressure inside the hull of the plane forces the door outwards which in turn presses on a seal and hence, to open a door in such a configuration, where 6 p.s.i. (pounds per square inch) of pressure is acting against several square feet of the door, one would need a tremendous amount of force, and even if the door was to be opened electronically or hydraulically, one would still expect rapid decompression of the cabin after opening the door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence it is categorically incorrect to claim that modern (new) airplanes can't open their doors mid flight. It is quite achievable, but after depressurizing the cabin. Here is a &lt;a href=&quot;http://news.nationalgeographic.com/news/2013/05/130528-airplane-door-open-midflight-pilot-eject/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt; for your further reading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following airplanes have Air-Stair installed. I'm not sure which of them has an over-ride to open this Air-Stair mid-air, but any airplane which does not have a cooper vane installed (Or any other external barrier) can open the Air-Stair midair (technically):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot; rel=&quot;noreferrer&quot;&gt;Lockheed L1011&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_VC-25&quot; rel=&quot;noreferrer&quot;&gt;Boeing VC 25&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-86&quot; rel=&quot;noreferrer&quot;&gt;Ilyushin Il-86&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DC-9/MD-80/MD-90/B-717&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some modified Airbus and Boeing planes have Air-Stairs too.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="946" LastEditDate="2015-06-23T22:14:20.737" LastActivityDate="2015-06-23T22:14:20.737" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16156" PostTypeId="2" ParentId="16147" CreationDate="2015-06-23T06:06:49.403" Score="3" Body="&lt;p&gt;Even though the Wikipedia article clearly states that :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Not long after the 1958 start of its flight test program, the&#xA;  development of the Arrow (including its Orenda Iroquois jet engines)&#xA;  was abruptly halted before the project review had taken place,&#xA;  sparking a long and bitter political debate.The&#xA;  controversy engendered by the cancellation and subsequent destruction&#xA;  of the aircraft in production remains a topic for debate among&#xA;  historians, political observers and industry pundits. &quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But later in the article a comprehensive paragraph goes on to add:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;From 1953, some senior Canadian military officials at the Chief of&#xA;  Staffs began to question the program. In June 1957, when&#xA;  the governing Liberals lost the federal election and a Progressive&#xA;  Conservative government under John Diefenbaker took power, the&#xA;  aircraft's prospects began to noticeably change. Diefenbaker, from the&#xA;  Canadian west, had campaigned on a platform of reining in what the&#xA;  Conservatives claimed was &quot;rampant Liberal spending&quot;. The Arrow was&#xA;  not the only major industrial project targeted during the campaign;&#xA;  others such as the &quot;million dollar monster&quot; postal-sorting computer&#xA;  from Ferranti Canada were also singled out for political scorn. A&#xA;  criticism that had been voiced in the 1950s in the media was that Avro&#xA;  Canada as a company had little interest in competing with its products&#xA;  in the market, and instead had come to rely solely upon the&#xA;  availability of government financing for its activities.&#xA;  Nonetheless, by 1958, the parent company had become Canada's third&#xA;  largest business enterprise and had primary interests in rolling&#xA;  stock, steel and coal, electronics and aviation with 39 different&#xA;  companies under the A. V. Roe Canada banner.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In August 1957, the Diefenbaker government signed the NORAD (North&#xA;  American Air Defense) Agreement with the United States,&#xA;  making Canada a partner with American command and control. The USAF&#xA;  was in the process of completely automating their air defence system&#xA;  with the SAGE project, and offered Canada the opportunity to share&#xA;  this sensitive information for the air defence of North America.&#xA;  One aspect of the SAGE system was the Bomarc nuclear-tipped&#xA;  anti-aircraft missile. This led to studies on basing Bomarcs in Canada&#xA;  in order to push the line further north, even though the deployment&#xA;  was found to be extremely costly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; The introduction of SAGE in Canada will cost around `$107 million`. Further improvements are required in the radar... NORAD has also recommended the introduction of the Bomarc missile... will be a further commitment of `$164 million`... All these commitments coming at this particular time... will tend to increase our defence budget by as much as `25 to 30%`.&#xA;&#xA;    — George Pearkes, then-Minister of National Defence, 1958[67]&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Defence against ballistic missiles was also becoming a priority. The&#xA;  existence of Sputnik had also raised the spectre of attack from space,&#xA;  and, as the year progressed, word of a &quot;missile gap&quot; began spreading.&#xA;  An American brief of the meeting with Pearkes records that Pearkes&#xA;  &quot;stated that the problem of developing a defence against missiles&#xA;  while at the same time completing and rounding out defence measures&#xA;  against manned bombers posed a serious problem for Canada from the&#xA;  point of view of expense&quot;. It is also said Canada could afford the&#xA;  Arrow or Bomarc/SAGE, but not both.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;By 11 August 1958, Pearkes requested cancellation of the Arrow, but&#xA;  the Cabinet Defence Committee (CDC) refused. Pearkes tabled it again&#xA;  in September, and recommended installation of the Bomarc missile&#xA;  system. The latter was accepted but, again, the CDC refused to cancel&#xA;  the entire Arrow program. The CDC wanted to wait until a major review&#xA;  in 31 March 1959. They cancelled the Sparrow/Astra system in September&#xA;  1958. Efforts to continue the program through cost-sharing with other countries were then explored.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;We did not cancel the CF-105 because there was no bomber threat, but because there was a lesser threat and we got the Bomarc in lieu of more airplanes to look after this.&#xA;&#xA;— George Pearkes, then-Minister of National Defence, 1959&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-23T06:06:49.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16157" PostTypeId="2" ParentId="16147" CreationDate="2015-06-23T06:08:26.553" Score="6" Body="&lt;p&gt;Since I'm not and was never a member of the Canadian Parliament or Canadian military top brass, this is pure speculation as you are likely to get from practically anyone else on this site with the possible exception of Rhino Driver (who is AFAICT a serving U.S. naval aviator).&lt;/p&gt;&#xA;&lt;p&gt;My guess is that the Canadians looked to their south, saw one of their nation's staunchest allies who also happened to be one of the two remaining superpowers after World War II, and concluded that they couldn't afford to compete in the Cold War arms race but could definitely afford to profit from our R&amp;amp;D. Canada and the U.S. formed NORAD in 1958 as a joint venture to defend North American airspace, so Canada knew the U.S. had its back. Canada, for its part, spent its defense dollars outfitting defensive SAM and ICBM-intercept fortifications along probable Soviet nuclear bomber routes, effectively forming the northern part of the North American nuclear shield.&lt;/p&gt;&#xA;&lt;p&gt;As far as not reviving Avro Canada now, the biggest answer is that Canada is so far behind the major powers in domestic aerospace technology that it would essentially have to recruit in the U.S. military-industrial complex anyway. In addition, compared to the USAF, the RCAF is &lt;em&gt;tiny&lt;/em&gt;, composed mainly of transports to move the Army around, with just 70-odd CF-18 fighters making up the total fixed-wing combat complement, and a handful of ASW helicopters seeing service at naval stations and on the Canadian Navy's dozen Halifax-class frigates. In short, Canada has no real need for a domestic military aerospace program, as demand is very low and it can get all it wants from its southern neighbor at preferential prices. They're in line, IIRC, for a shipment of F-35s once Lockheed gets the bugs worked out.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;EDIT FROM COMMENT:&lt;/strong&gt; The comment says that Canada could build planes primarily for export. Such an effort would be doomed to fail for three reasons:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The RCAF itself, given its small size and its outstanding relations with the U.S., would be unlikely to buy the planes. When looking for export buyers, your best marketing is the success of your design in your home country's military, so not having your military use the design at all is a big black mark (the F-5 is the only fighter I can think of that managed decent export success despite the U.S. never widely adopting it; even then, the USAF did have some test deployments of F-5 squadrons in Vietnam for the primary purpose of giving Northrop their backing to market the plane for export).&lt;/p&gt;&#xA;&lt;p&gt;This presents a Catch-22 for financing and R&amp;amp;D efforts; you're unlikely to get the funds to start working on a plane without any acknowledged demand for it, and with the Canadian aerospace industry being dormant for over almost 60 years, you're unlikely to generate demand for an as-yet nonexistent fighter from an unproven design team. So you have to get the money to build the fighter, and you have to build the fighter to get the money.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Again, the Canadian aerospace industry is dormant, and therefore way behind the times. A joint venture with U.S. or European firms to provide a knowledge transfer to home-grown aerospace engineers seems like the only option to develop something new, when those same firms would then have to openly compete with the resulting firm and its designs. A new Canadian aerospace company would be reduced, as I said, to sniping U.S. talent to jump-start design work.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some countries that formerly imported jets are starting to look toward domestic production, making a primary export strategy that much more unappealing. Pakistan is the foremost example; their political relationship with practically all the major exporting countries is pretty shaky, and designs still in production for export are getting really expensive, so they're designing the J-17 jointly with China to have an inexpensive, capable fighter they can build in-house without relying long-term on imports. The resulting fighter (an interesting combination of design features from the F-16, F-18, and European designs like the Gripen and Rafale), on paper, is about 40 years behind the times, comparable to Gen-4 and 4.5 fighters like the F-15, F-16, MiG-29, Su-27, Typhoon and Rafale. But, the J-17 is projected to have a flyaway cost of only about \$15 milion a plane, which is a bargain compared to the aforementioned export choices, which start at about \$40 mil per plane and go up to \$110 mil.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-10T17:46:40.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16158" PostTypeId="2" ParentId="16151" CreationDate="2015-06-23T06:53:53.673" Score="14" Body="&lt;p&gt;There is a really good explanation of emergency situation over at the &lt;a href=&quot;http://www.skybrary.aero/index.php/Emergency_or_Abnormal_Situation&quot; rel=&quot;noreferrer&quot;&gt;SkyBrary&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;An emergency situation is one in which the safety of the aircraft or of persons on board or on the ground is endangered for any reason.&lt;/p&gt;&#xA;&lt;p&gt;An abnormal situation is one in which it is no longer possiible to continue the flight using normal procedures but the safety of the aircraft or persons on board or on the ground is not in danger.&lt;/p&gt;&#xA;&lt;p&gt;Emergency or abnormal situations may develop as a result of one or more factors within or outside an aircraft, for example:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fire on board the aircraft;&lt;/li&gt;&#xA;&lt;li&gt;Aircraft component failure or malfunction (e.g. engine failure, landing gear malfunction or loss of pressurisation);&lt;/li&gt;&#xA;&lt;li&gt;Shortage of fuel (or other essential consumable substance);&lt;/li&gt;&#xA;&lt;li&gt;Flight crew uncertain of position;&lt;/li&gt;&#xA;&lt;li&gt;Worsening weather;&lt;/li&gt;&#xA;&lt;li&gt;Pilot incapacitation (e.g. as a result of illness);&lt;/li&gt;&#xA;&lt;li&gt;Aircraft damage (e.g. as a result of collision, bird strike or extreme weather;&lt;/li&gt;&#xA;&lt;li&gt;Illegal activity (e.g. bomb-threat, wilful damage or hi-jacking).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So in short, anything that puts the flight in danger can be considered an emergency.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Is ATC allowed to judge what is or is not an actual emergency, or must they prioritize any aircraft declaring one?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If the pilot declares emergency, ATC will provide assistance and support to the flight without judging whether it is an actual emergency or not. ATC cannot know in most cases, nor are they really required to analyse the situation to come to that conclusion. Their whole responsibility is to ensure the flight receives all required information and support to either end the abnormal/emergency situation or land at a suitable airport.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Does fault or blame matter at the time the emergency is declared? Will ATC de-prioritize a situation that is obviously the pilot's fault, like flying into the only cloud for 50 miles in any direction?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;No, they will not de-prioritize based on the type of emergency. Even if a pilot flew VFR into IMC conditions, he is still in a life-threatening situation from which he needs to recover, so assigning blame or guilt is not helpful here, nor would that be the ATC's job. This is the Civil Aviation Authorities' responsibility, once the flight is back in safe conditions. ATC may file a report, though, but not during the emergency, but as an aftermath.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Is there anything you still can't do as PIC in an emergency situation? Apparently in an emergency you can do a lot of things that would get your license pulled in any other scenario, like violating separation minimums, entering airspace that's normally off-limits like R-zones and Class A space, running on instruments without a rating, etc. While these things are still dangerous, it is apparently the pilot's prerogative to resolve the emergency however he can. Is there anything a plane declaring an emergency still must do other than fly the plane, or conversely something he still cannot do like get too close to Air Force One?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Technically, once you have declared an emergency, you can do whatever is required to keep the flight safe and prepare for an emergency landing. If you need to enter otherwise controlled or restricted airspace, this will be made possible by ATC via coordination with adjacent units. Without knowing FAA regulations on this specifically, I would daresay that distress traffic could have priority over the Air Force One.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;After declaring an emergency in flight, what should be done after the plane's back on the ground (hopefully safely)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Unless your CAA or their respective investigative service is not already waiting for you, you should remain with your aircraft (unless being treated for medical issues and taken to a hospital) and wait for them to arrive. If in doubt, you can call the police and they will notify the relevant authorities.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-23T07:04:12.887" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16159" PostTypeId="2" ParentId="16060" CreationDate="2015-06-23T07:03:43.280" Score="3" Body="&lt;p&gt;The helicopter Collective and Cyclic controls are connected to the rotor bladesby swash-plates. The following is a swash-plate :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F2tvY.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following animation shows the connection assembly working :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swash plate in the resting position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KQkAS.gif&quot; alt=&quot;Swash plate in the resting position.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A raised swash plate causing negative collective blade pitch and thus down force. Note that the control arms are on the trailing sides of the blades, causing raised swash plate to decrease the blade pitch. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ATzxO.gif&quot; alt=&quot;Swash Plate Raised&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tilted swashplate giving cyclic blade control. Note the change in pitch of the blades during rotation.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/HcWXa.gif&quot; alt=&quot;A tilted swashplate giving cyclic blade control. Note the change in pitch of the blades during rotation.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source : &lt;a href=&quot;https://en.wikipedia.org/wiki/Swashplate_%28aeronautics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-23T07:03:43.280" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16160" PostTypeId="2" ParentId="14697" CreationDate="2015-06-23T07:14:58.957" Score="1" Body="&lt;p&gt;From the &lt;a href=&quot;https://books.google.fr/books?id=FiEapaNgjLcC&amp;amp;pg=PA298&amp;amp;redir_esc=y#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1cLJZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/d9mrR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/G4oQf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LkPOl.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA; It shows how to calculate theoretical maximum altitude a Helicopter can achieve&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-23T07:14:58.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16161" PostTypeId="2" ParentId="13285" CreationDate="2015-06-23T07:21:25.840" Score="1" Body="&lt;p&gt;According to the &lt;a href=&quot;http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1377362608/4&quot;&gt;Source&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The bottom is for the icon in track up mode. For the North up mode, It&#xA;  Depends on the Heading. The fix icon should be placed on one of the 8&#xA;  positions (up left, up right, up center, bottom left, bottom right,&#xA;  bottom center). For example, if the Heading is 45°, the fix icon is&#xA;  placed on the bottom left part of the screen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-23T07:21:25.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16162" PostTypeId="1" AcceptedAnswerId="16182" CreationDate="2015-06-23T07:26:22.963" Score="49" ViewCount="8285" Body="&lt;p&gt;Why do rotorcraft like helicopters have such limited range, rarely exceeding 1000 km on a full tank? For example, the range of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_AH-64_Apache&quot; rel=&quot;noreferrer&quot;&gt;Apache&lt;/a&gt; is close to 425 km, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-26&quot; rel=&quot;noreferrer&quot;&gt;MI-26's&lt;/a&gt; is 800 km.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="4108" LastEditDate="2018-06-11T09:07:25.543" LastActivityDate="2019-08-09T13:48:23.463" Title="Why do helicopters have such limited range?" Tags="&lt;helicopter&gt;&lt;rotorcraft&gt;&lt;range&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="16163" PostTypeId="2" ParentId="16162" CreationDate="2015-06-23T07:54:54.543" Score="30" Body="&lt;p&gt;Because they are less efficient than fixed-wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The rotor blades need to move significantly faster than the craft and therefore incur significantly more drag than fixed wings.&lt;/li&gt;&#xA;&lt;li&gt;More drag is caused by the suboptimal lift distribution. The centre of the rotor creates little lift because the blades are slow there and is shielded by the fuselage, which causes additional vortices in the middle of the downwash.&lt;/li&gt;&#xA;&lt;li&gt;The rotor diameter is limited by blade tip speed and material strength, which again limits the efficiency, since it can only affect limited amount of air and has to therefore accelerate it to higher speed, which needs more energy.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft achieve efficiency by flying high, where the air is thinner and thus drag is lower, and compensate the lower lift by flying faster. But for helicopters it is not possible due to physical limits on the rotor size and speed, nor would it really work, because their induced drag does not decrease so much with speed.&lt;/li&gt;&#xA;&lt;li&gt;Due to all those limitations, helicopters have relatively less lift for their dry weight and therefore can't take as much fuel.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-06-23T12:25:40.643" LastActivityDate="2015-06-23T12:25:40.643" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16165" PostTypeId="5" CreationDate="2015-06-23T09:06:16.640" Score="0" Body="&lt;p&gt;The Robinson R44 is a four-seat light helicopter produced by the Robinson Helicopter Company since 1992. Based on the company's two-seat Robinson R22, the R44 features hydraulically assisted flight controls. The R44 was first flown on 31 March 1990, and received FAA certification in December 1992, with the first delivery in February 1993&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The R44 is a single-engined helicopter with a semi-rigid two-bladed main rotor and a two-bladed tail rotor and a skid landing gear. It has an enclosed cabin with two rows of side-by-side seating for a pilot and three passengers. Tail rotor direction of rotation on the R44 is reversed compared to the R22 for improved yaw control authority. On the R44 the advancing blade is on the bottom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designed during the 1980s by Frank Robinson and his staff of engineers, the R44 first flew on 31 March 1990. The R44 Astro was awarded an FAA Type Certificate in December 1992, with the first deliveries taking place in January 1993. In January 2000, Robinson introduced the Raven with hydraulically assisted controls and adjustable pedals. In July 2002, Robinson introduced the Raven II featuring a more powerful, fuel-injected engine and wider blades, allowing a higher gross weight and improved altitude performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Robinson produced 186 R44's in 2014&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T11:10:02.210" LastActivityDate="2015-06-23T11:10:02.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16166" PostTypeId="4" CreationDate="2015-06-23T09:06:16.640" Score="0" Body="The Robinson R44 is a four-seat light helicopter produced by the Robinson Helicopter Company since 1992. Based on the company's two-seat Robinson R22, the R44 features hydraulically assisted flight controls. The R44 was first flown on 31 March 1990, and received FAA certification in December 1992, with the first delivery in February 1993" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-23T09:51:17.707" LastActivityDate="2015-06-23T09:51:17.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16169" PostTypeId="1" CreationDate="2015-06-23T09:54:04.460" Score="2" ViewCount="136" Body="&lt;p&gt;Having just read &lt;a href=&quot;http://www.bbc.co.uk/news/uk-northern-ireland-33226740&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; story about a plane which was diverted to Belfast following a passenger's abusive and threatening behaviour, I was wondering why the plane had to dump its fuel (as explained in the news article). It seems quite wasteful, surely the airline would prefer the crew to pacify or apprehend the passenger and carry on to its destination. &lt;/p&gt;&#xA;" OwnerUserId="9014" LastEditorUserId="9014" LastEditDate="2015-06-23T10:01:44.207" LastActivityDate="2015-06-23T10:01:44.207" Title="Why did the diverted Rome - Chicago flight dump its fuel?" Tags="&lt;fuel&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-06-23T10:07:49.840" ContentLicense="CC BY-SA 3.0" />
  <row Id="16170" PostTypeId="1" CreationDate="2015-06-23T09:55:13.590" Score="20" ViewCount="8355" Body="&lt;p&gt;Is there any airline which are able to get the complete 20% fuel efficiency on their 787 with respect to 767 it is going to replace, as told by Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have read that one of the early customer like Air India are not able to get even 15% of fuel efficiency on their Dreamliners.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="14897" LastEditDate="2017-08-12T06:44:18.947" LastActivityDate="2019-05-27T17:15:37.300" Title="Did any Boeing 787 operator achieve the 20% fuel efficiency improvement over the 767?" Tags="&lt;fuel&gt;&lt;efficiency&gt;&lt;boeing-787&gt;&lt;economics&gt;&lt;boeing-767&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16171" PostTypeId="1" AcceptedAnswerId="16172" CreationDate="2015-06-23T09:57:16.063" Score="13" ViewCount="2569" Body="&lt;p&gt;&lt;strong&gt;Amateur in aviation&lt;/strong&gt;, so please explain the purpose of navigational fix and its characteristics. How is a navigational fix being placed around the runway, or how it is determined this would be the right spot? How does it help a aircraft to make it land?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And where would I get the details of navigational fixes for a airport near me? Is there a API, does ICAO provide any info? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Any links/charts could be of great help.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3449" LastActivityDate="2015-06-23T10:46:33.740" Title="What is a navigational fix? Where can I get navigational fixes for a local airport?" Tags="&lt;landing&gt;&lt;navigation&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16172" PostTypeId="2" ParentId="16171" CreationDate="2015-06-23T10:19:04.407" Score="12" Body="&lt;p&gt;A navigational fix is a waypoint that can be used to navigate to, from or between airports or other navigational fixes. Navigational fixes can be GPS-based coordinates, radio-based navigational aids like VORs or NDBs or airport themselves, which have a defined airport reference point with set coordinates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigational fixes or aids are usually not placed around runways, but those that are used for approaches or departures (mostly VOR or NDBs) are placed at or in the vicinity of the airport. See below for the placement of the Barmen (BAM) VOR, which is one of the approaches fixes used for the ILS approach to runway 23L and 23R and the, nowadays no longer used, NDBs DX and LI as the outer markers for the instrument approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/p6Qwr.jpg&quot; alt=&quot;EDDL Barmen&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.skyvector.com)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigational fixes required for approaches or departures to a specific airport will be available in the countries' AIP, in the publications for the specific approach or departure routing, e.g. navigational fixes along a STAR or Transition from the Initial Approach Fix (which is a navigational fix as well) to the Final Approach Fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uJyfk.jpg&quot; alt=&quot;Transitions VATUSA&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: VATUSA)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above displays the navigational fixes for the transitions/arrivals into Memphis International Airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a list of available radio navigational aids around an airport, you can try sources like &lt;a href=&quot;https://skyvector.com/airport/EDLW/Dortmund-Wickede-Airport&quot; rel=&quot;noreferrer&quot;&gt;SkyVector&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-06-23T10:19:04.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16173" PostTypeId="2" ParentId="16170" CreationDate="2015-06-23T10:28:26.583" Score="20" Body="&lt;p&gt;You have not defined your benchmark/reference value, but a three-year-old &lt;a href=&quot;http://aviationweek.com/awin/operators-reporting-positive-787-fuel-burn-results&quot;&gt;article&lt;/a&gt; suggests this was possible depending on definition even at a very early stage for some airlines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ANA earlier this month was the first to reveal that its aircraft were producing around 21% lower fuel burn on international flights compared to the 767-300ER that the 787 is designed to replace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also say however: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After its first six months of service, ANA says the 787 efficiency levels are slightly up on the 20% savings originally expected at the beginning of the program. On domestic routes, the saving is 15-20%, which meets expectations, say ANA officials.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-06-23T10:28:26.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16174" PostTypeId="2" ParentId="16171" CreationDate="2015-06-23T10:46:33.740" Score="12" Body="&lt;p&gt;This is a very broad question, but I'll give it a shot:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why do Airplanes need navigation?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Navigating an airplane is like driving a car with sole reliance on maps. Except you don't have any signs hanging in the air that might give you hints where to go, and in bad weather it is hard to determine your position by looking down to the ground. Thus a pilot needs other means of position determination. &#xA;Flying goes back over 100 years now; way before people even thought about GPS being possible, flights were already made by reference to navigation aids. A (by now) kind of old fashioned navigation aid is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-directional_beacon&quot;&gt;NDB(Non-Directional Beacon)&lt;/a&gt; which in its day's was very helpful and was even used for approaches! This is now replaced by &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot;&gt;VORs (Very high frequency Omnidirectional Beacons)&lt;/a&gt;. Building a VOR is quite a task, in the US there are many compared to other countries, yet not enough for the amount of traffic. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why are there Navigational Fixes?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Cars use streets to get from A to B. Imagine all air traffic going straight from their departure to their destination airport, this would end in a huge chaos. Therefore there were &quot;streets&quot;, so called &lt;strong&gt;airways&lt;/strong&gt;, established from  one VOR to the other. Traffic flies along these routes, just like cars drive along streets. But the VORs only are still not enough points on the map to navigate traffic. A simple curve would need multiple VORs to be described (Yes, there are arcs around VORs but that's something different). Thus &lt;strong&gt;waypoints&lt;/strong&gt; were created. Before the time of GPS they could usually be identified by two radials from two different VORs. By now there are more waypoints out there that are described by &lt;strong&gt;coordinates&lt;/strong&gt; only and can only be used with a GPS.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Where are navigational fixes placed?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Usually they are placed in a way so that they help out in coordinating traffic. You will most likely find more fixes around airports, as they offer possibilities to controllers to spread the traffic and, whats even more important, guide planes to the runway. There are so called &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_terminal_arrival_route&quot;&gt;&lt;strong&gt;STARs&lt;/strong&gt; (Standard Terminal Arrival Route)&lt;/a&gt; which bundle traffic approaching the airport from different directions towards the same runways, followed by &lt;strong&gt;transitions&lt;/strong&gt; which guide them via the &lt;strong&gt;IAF&lt;/strong&gt;(Initial Approach Fix) to the final approach. All those procedures are described using the &lt;strong&gt;waypoints, VORs and other navigational aids.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Where would you get details about fixes?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To be honest, I don't know of any source that can be used for real world flying. I know of databases used for simulator flying, which are still up to date and probably contain almost exactly the same information. Those are called &quot;AIRAC&quot; (not to confuse with the real world AIRAC cycle though!) and can be downloaded or come with certain programs. From there you should be able to get the information you need (if you want to write a program using this information). &lt;strong&gt;Again, these are not for real world flying!&lt;/strong&gt; If you are just curious about the waypoints around you, &lt;a href=&quot;http://skyvector.com/&quot;&gt;this website&lt;/a&gt; is one example of a source for these kind of things (clicking &quot;World Lo&quot;/&quot;World Hi&quot; will display these waypoints). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this answers your questions, if not try to ask a bit more precise! &lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2015-06-23T10:46:33.740" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16176" PostTypeId="1" AcceptedAnswerId="16184" CreationDate="2015-06-23T11:14:08.633" Score="18" ViewCount="6191" Body="&lt;p&gt;Some Helicopters like Russian Mi-24, UH-60 etx have Stub Wings. What is the role of such wings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Russian Mi-24&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RBNh7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UH-60&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NAzgr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8814" LastActivityDate="2020-07-11T06:19:27.963" Title="What is the use of Stub Wings on Helicopters?" Tags="&lt;helicopter&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16177" PostTypeId="1" AcceptedAnswerId="16181" CreationDate="2015-06-23T11:19:24.493" Score="24" ViewCount="31894" Body="&lt;p&gt;Given the fact that most helicopters nowadays use turbo shaft engines and many aeroplanes still use turboprop engines (which are essentially turbo shaft engines with a propeller), how do you differentiate between a helicopter engine and an aircraft engine? What are the differences between the two?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;p.s. I am not looking for differences in turboprop and turboshaft, but differences in helicopter and plane engines&lt;/p&gt;&#xA;" OwnerDisplayName="user8823" LastEditorDisplayName="user8823" LastEditDate="2015-06-24T09:41:58.103" LastActivityDate="2017-08-08T05:00:09.727" Title="What are the differences between a helicopter engine (turboshaft) and an aircraft engine (turboprop)?" Tags="&lt;helicopter&gt;&lt;engine&gt;&lt;turboprop&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16178" PostTypeId="2" ParentId="16170" CreationDate="2015-06-23T11:31:53.537" Score="15" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot;&gt;Wikipedia's B787&lt;/a&gt; article states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to data from launch customer All Nippon Airways, the 787&#xA;  surpassed the promised 20% fuel burn reduction compared to that of the&#xA;  Boeing 767.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This newer (8 months old) &lt;a href=&quot;http://www.flightglobal.com/news/articles/analysis-after-three-years-in-service-how-is-787-performing-405814/&quot;&gt;article&lt;/a&gt; states that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air Canada and Japan Airlines are on the way to achieve it. &lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-06-23T11:31:53.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16179" PostTypeId="2" ParentId="16176" CreationDate="2015-06-23T11:36:55.087" Score="11" Body="&lt;p&gt;They're used for hanging munitions, external stores, etc. on. You can see in the picture of the Mi-24 that it has several rocket pods attached. They're referred to as &quot;hardpoints&quot; or &quot;pylons&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that the reasons the pylons hang down from horizontal wings, rather than being attached more directly to the helicopter include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Compatibility with existing airplane-based systems.&lt;/li&gt;&#xA;&lt;li&gt;Moves rocket exhaust away from the body of the helicopter.&lt;/li&gt;&#xA;&lt;li&gt;There's not enough room under the helicopter to hang them there.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2719" LastActivityDate="2015-06-23T11:36:55.087" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16180" PostTypeId="1" AcceptedAnswerId="16190" CreationDate="2015-06-23T13:30:38.273" Score="25" ViewCount="2802" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AxD4J.jpg&quot; alt=&quot;Turbofan Inlet&quot;&gt;&lt;BR&gt;(Image Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:B787-2139.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeing that everything is radially symmetric (apart from the nacelle mount, naturally), I wonder why the inlet (the front part of the nacelle) is usually skewed?&lt;/p&gt;&#xA;" OwnerUserId="4291" LastEditorUserId="14897" LastEditorDisplayName="user12485" LastEditDate="2017-05-18T14:43:18.083" LastActivityDate="2019-08-29T12:20:23.233" Title="Why are turbofan inlets leaned/angled forward?" Tags="&lt;jet-engine&gt;&lt;turbofan&gt;&lt;engine-design&gt;&lt;inlet&gt;&lt;nacelle&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16181" PostTypeId="2" ParentId="16177" CreationDate="2015-06-23T14:20:34.050" Score="24" Body="&lt;p&gt;There are no major differences between a turboprop used on an airplane and a turboshaft used on an helicopter. All power is collected by the turbine shaft which rotates the blades through a gearbox.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a gas turbine used in helicopter, airplane, train, and even snowplow is the well-known &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney PT6&lt;/a&gt;. It has different versions. The two versions shown below are the PT6A for a propeller (top), and the PT6B for an helicopter (bottom, with a large gearbox). Each sub-family has variant for different powers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/U3aSa.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.pt6nation.com/fr/articles/article/histoire-le-moteur-pt6-propulse-par-linnovation/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7rvUN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://hamawy.net/resume/job/www.pw.utc.com/media_center/images_library/images_pwc_library.asp.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the two images, from right to left: The accessory box powered by the compressor section, the air intake recognizable by its filter, the compressor (not visible), the combustion chamber (yellow color on the bottom image) with its circle of igniters, the turbine (not visible), the exhaust (the big hole, best visible on the bottom image), the power gearbox with different output shafts.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are different types for aero-engines, including turbojet, turbofan, turboprop and turboshaft (I exclude the ramjet which is not used in civilian aviation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All types are based on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_turbine&quot; rel=&quot;noreferrer&quot;&gt;gas turbine&lt;/a&gt;, but the way the turbine participates to the motion is different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WzzGk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.wonderwhizkids.com/index.php/aircrafts&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While airplanes use all types, helicopters cannot use the jet action/reaction principle (tip jet excluded for simplification).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gas turbine can be the same for turboshaft and turboprop engines, but will be fitted with appropriate elements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The rotational speed of the shaft will be adjusted to accommodate the rotor or the propeller. This is done using a gear reduction system. An helicopter rotor turns slower than an airplane propeller.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air intake and exhaust are adapted. It rather common to have the air intake on the opposite side of the power output shaft. For a pulling propeller, this means the intake will be aft, and air must be collected forward and ducted to the engine intake.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The power output shaft is usually used to bear the propeller tension caused by the lift, while on an helicopter, the rotor tension is borne by the frame.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The accessory box is usually powered by the compressor side of the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A turboshaft don't provide the bleed air extraction, there is no cabin pressurization required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6bUKB.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://greatlakeshelicopter.us/UH-1F.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gas turbines used in both cases are frequently &lt;a href=&quot;http://www.theairlinepilots.com/forumarchive/agk/freeturbine.jpg&quot; rel=&quot;noreferrer&quot;&gt;free turbines&lt;/a&gt;, where the compressor section and the turbine (power) section rotate independently of each other. This allows to produce electricity or hydraulic power on the ground without turning the blades.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-06-23T19:24:35.223" LastActivityDate="2015-06-23T19:24:35.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16182" PostTypeId="2" ParentId="16162" CreationDate="2015-06-23T14:24:52.363" Score="50" Body="&lt;p&gt;Helicopters are very inefficient in forward flight, for several reasons.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Consider Glauert's high speed assumption, i.e. the helicopter can be represented as an aircraft with a circular wing during high speed flight.  Now, if you know anything about basic fixed-wing performance, you'll realize immediately that this implies an aspect ratio just over 1, which is awfully small.  You may recall that for a fixed-wing aircraft, induced drag is inversely proportional aspect ratio--so a very low aspect ratio means very high induced drag!  Induced drag is normally not a big deal for fixed-wing aircraft at high speed because it's proportional to the square of the lift coefficient (which decreases with speed), but...&lt;/li&gt;&#xA;&lt;li&gt;In reality, the situation for a helicopter is even worse!  Glauert's assumption assumes we have an ideal rotor, i.e. one that has a uniform induced velocity throughout.  In practice, the inflow distribution over the rotor is highly non-uniform, especially at high speeds where the advancing side of the rotor is in a very different aerodynamic environment than the retreating side.  Even on a very simple level, the &quot;working area&quot; swept on the retreating side is much smaller than that on the advancing side. Since lift needs to be balanced, momentum theory implies a higher induced velocity over the smaller area &quot;worked&quot; by the retreating side, and therefore a much higher induced drag at high speeds than an equivalent fixed wing aircraft.&#xA;&lt;a href=&quot;http://www.mentor.com/products/mechanical/engineering-edge/volume4/issue1/helicopter-rotator-simulation&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QjEiU.png&quot; alt=&quot;TsAGI RC-VTOL Rotor Wake Geometry&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.mentor.com/products/mechanical/engineering-edge/volume4/issue1/helicopter-rotator-simulation&quot; rel=&quot;noreferrer&quot;&gt;Rotor wake computation from TsAGI RC-VTOL code (Kritsky, B.S).&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;As the helicopter goes faster, and as the rotor turns more slowly, more of the retreating side blade will stall, which leads to a dramatic increase in drag. This starts on the inboard section of the blades, and moves outwards as the advance ratio (ratio between flight speed and tip speed) increases.  In fact, the most inboard sections of the blade will even be in reversed flow--and airfoils don't work too well backwards.&lt;/li&gt;&#xA;&lt;li&gt;On the advancing side, things are bad too, but for different reasons. The profile drag of the rotor increases rapidly with speed.  Moreover, as the advance ratio increases, the advancing tip Mach number also increases--and as the blades get into the high transonic regime, local shocks begin to form and lead to even larger increases in drag.  This can be delayed by slowing the rotor down, but that makes the problems on the retreating side even worse!  In general, it's hard to develop airfoils that work well in both regimes.&lt;/li&gt;&#xA;&lt;li&gt;Outside of the rotor itself, the rotor hub is very draggy, between the main rotor shaft, pitch links, swashplate, hinges and blade grips, etc.  Helicopters usually have pretty &quot;utilitarian&quot; fuselages, as well, which are not so well streamlined.  Plus, you have the tail rotor, which has most of the same problems as the main rotor.&lt;/li&gt;&#xA;&lt;li&gt;Back to the specific question of range, the Bregruet range equation says that the range of an aircraft is proportional to the lift-to-drag ratio and the speed of the aircraft.  We've already established that the L/D of a helicopter is pretty bad, especially at speed.  So, the cruise speed is going to be pretty low and the L/D is going to be pretty low, so to sum up, the range is going to be really low.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The tradeoff is that the helicopter is very good at hovering--even amongst VTOL platforms, the helicopter is the most efficient. Speed and range are the price you pay for that capability.&lt;/p&gt;&#xA;" OwnerUserId="9015" LastEditorUserId="9015" LastEditDate="2015-06-23T14:50:32.477" LastActivityDate="2015-06-23T14:50:32.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16183" PostTypeId="1" AcceptedAnswerId="16186" CreationDate="2015-06-23T14:37:03.570" Score="6" ViewCount="378" Body="&lt;p&gt;Is it possible for navigational instruments to get affected by static electricity or electrical discharges like lightning? If so, how does this happen?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="8730" LastEditDate="2016-01-31T21:26:57.503" LastActivityDate="2019-10-22T15:37:08.897" Title="Can static electricity affect navigational instruments?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;&lt;lightning&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16184" PostTypeId="2" ParentId="16176" CreationDate="2015-06-23T14:50:26.233" Score="22" Body="&lt;p&gt;In addition to serving as support for weapons, we must have in mind that they're both quite fast for a helicopter - 335 km/h (208 mph) for Mi and 294 km/h (183 mph) for UH. At such speeds, even small wings yield considerable aerodynamic effects, just like in planes. From &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-24&quot;&gt;Wikipedia article&lt;/a&gt; we can learn that Mi's wings can provide up to 25% of total lift at speed and important stability to counter tendency to Dutch Roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Curiously, both mentioned platforms exist in wingless configuration. For UH-60 it's quite common, while Mi-24 had it's wings removed for breaking records. This hints that Mi-24 is much more dependent on it's wings than UH-60.&lt;/p&gt;&#xA;" OwnerUserId="3903" LastActivityDate="2015-06-23T14:50:26.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16185" PostTypeId="1" AcceptedAnswerId="16188" CreationDate="2015-06-23T15:04:55.423" Score="11" ViewCount="6675" Body="&lt;p&gt;Planes can sometimes be seen &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_advertising#Fixed-wing_aircraft&quot; rel=&quot;noreferrer&quot;&gt;towing banners&lt;/a&gt; around large cities or events. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What kind of plane is good for this type of flight? With banners they appear to be flying slower than usual. Is this just an illusion?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the practical or regulatory requirements that the plane must meet to be capable? I am tagging with FAA but information about other jurisdictions is welcome.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-06-23T15:40:30.770" LastActivityDate="2017-03-30T05:33:20.920" Title="What kinds of planes can tow banners?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16186" PostTypeId="2" ParentId="16183" CreationDate="2015-06-23T15:09:32.327" Score="5" Body="&lt;p&gt;This will depend on the system, but the over all answer would be &lt;strong&gt;Yes&lt;/strong&gt; at least to some extent. When talking about VOR/VORTAC/DME/NDB/GPS or any other nav system that relies on both a device in the plane as well as a device elsewhere we must consider how these devices talk. In this case we are talking about radio waves (&lt;a href=&quot;https://en.wikipedia.org/wiki/Electromagnetic_radiation&quot; rel=&quot;nofollow noreferrer&quot;&gt;em propagation&lt;/a&gt;), and lighting &lt;a href=&quot;http://www.lightning.ece.ufl.edu/PDF/Zurich/1T01.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;does produce an EM field&lt;/a&gt; so it has the capability to interfere. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said &quot;interference&quot; has both a technical term and a reality IMO. On paper, yes this may interfere with the signal but in reality lightning is fast and isolated so its momentary interference may not interfere with the operation of the device over a usable amount of time or may cause a momentary drop out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Local INS (&lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inertial Navigation Systems&lt;/a&gt;) if you have it would remain generally unaffected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another issue that presents itself if the lighting is very very close to the aircraft and will be more of an issue with composite aircraft. For what it's worth, if the whole skin of an airplane is conductive (as with metal skinned aircraft) it will act as a pretty solid &lt;a href=&quot;http://theaviationist.com/tag/faraday-cage/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Faraday cage&lt;/a&gt;. This will vary from plane to plane but is generally true. Thus if the lightning generates a strong enough EM pulse the interior of the plane will be protected from it. On a composite based plane you potentially expose yourself to flux related power surging. It should be noted that the critical electronics are protected from this kind of damage.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2019-10-22T15:37:08.897" LastActivityDate="2019-10-22T15:37:08.897" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="16187" PostTypeId="2" ParentId="14864" CreationDate="2015-06-23T15:13:29.853" Score="4" Body="&lt;p&gt;I have discovered some more information regarding the S-duct design in an L-1011 marketing book.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2zzqC.jpg&quot; alt=&quot;S-Duct Payload Benefits&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;S-Duct Payload Benefits&lt;/strong&gt;&#xA;  The S-duct center engine location benefits payload by its lower fuselage weights. It allows a longer constant fuselage section thereby adding seating space. The more effective rudder allows the engines to be located further outboard on the wings and provides an optimized center cabin door location. The exhaust efflux provides an effective fineness ratio increase and hence reduces drag.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Do9rb.png&quot; alt=&quot;Center Image Position&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Center Engine Position&lt;/strong&gt;&#xA;  In the S-duct arrangement the engine is 10 ft. lower than a fin mounted engine. This permits easier access for maintenance or engine changes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-23T15:18:59.633" LastActivityDate="2015-06-23T15:18:59.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16188" PostTypeId="2" ParentId="16185" CreationDate="2015-06-23T15:31:47.063" Score="11" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What kind of plane is good for this type of flight?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The cheap kind. Joking aside, the exact airplane to use depends on the size of the banners or billboards you're going to be towing, but generally speaking you want something reasonably rugged, with good slow flight characteristics, sufficient engine power to be able to overcome the added drag from the banner, and, hopefully, some decent fuel consumption. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not entirely kidding about the cheap part though; banner towing is hard on the airplanes and carries a higher-than-average degree of risk, so you do want to stay away from airplanes that will be expensive to fix, if you can help it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for specific types, I've seen banners towed with everything from -152s to Grumman Agcats; a large banner tow operation apparently had a Super Cub with an O-540 bolted to it, so you'll see a ton of different things, but tailwheels seem to be the norm, at least in the US, and many outfits will make additional modifications such as removing engine cowlings to help with cooling.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With banners they appear to be flying slower than usual. Is this just an illusion?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, they are indeed flying slower. First of all, the added drag from the banner slows the airplane down all by itself. Secondly, you're being paid to advertise, so you want to make sure that people can read whatever sign you're towing. You're not flying the ragged edge of the stall (it's dangerous, uneconomical, and unnecessarily hard on the engine), but you're probably going to be flying on the backside of the power curve.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the practical or regulatory requirements that the plane must meet to be capable?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In addition to the practical considerations we've talked about above, banner towing operations require a waiver from the FAA. The company has to apply for it and every pilot must be trained in banner tow operations, pass a review from an approved FAA inspector (who will be watching you perform picks and drops from the ground), and be added to the waiver. The aircraft and tow hitch mechanisms also have to be inspected and approved for banner tow operations, and added to the waiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/faa-fs.pdf&quot; rel=&quot;noreferrer&quot;&gt;Here&lt;/a&gt; is the current FAA Banner Tow Information handbook, covering equipment, operations, waiver information, and other assorted miscellaneous if you're curious to learn more.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-06-23T15:31:47.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16189" PostTypeId="2" ParentId="16185" CreationDate="2015-06-23T15:33:57.957" Score="3" Body="&lt;p&gt;Generally speaking (I spend a lot of time on the shores of NJ) I see &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-25_Pawnee&quot; rel=&quot;nofollow&quot;&gt;Piper Pawnees&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-18_Super_Cub&quot; rel=&quot;nofollow&quot;&gt;Super Cub's&lt;/a&gt;, and a variety of  &lt;a href=&quot;https://en.wikipedia.org/wiki/American_Champion_Citabria&quot; rel=&quot;nofollow&quot;&gt;Citabrias&lt;/a&gt;. Here is a &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=51985&quot; rel=&quot;nofollow&quot;&gt;good thread&lt;/a&gt; discussing it. Keep in mind that a banner creates a lot of drag and will greatly effect a plane that is flying cross wind so power is a concern. Just this past weekend there was a super cub towing a banner over the shore that i was watching pretty closely. They were flying up the shore with almost a 45 degree headwind at about 25Kts (I didn't have the winds aloft on hand that was ground speed). At some points it almost seemed as if he was not moving and at others it seemed as if he was being blown out to sea. It was an interesting real world visualization on the effect of crosswind for sure.    &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-23T15:33:57.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16190" PostTypeId="2" ParentId="16180" CreationDate="2015-06-23T15:45:30.977" Score="20" Body="&lt;p&gt;The inlet angle is a compromise between cruise, when the aircraft has a low angle of attack, and the take-off and climb phase, when the engine runs at maximum thrust, and the angle of attack is several degrees higher than during cruise. Especially right after rotation, when the aircraft is heavy and slow, the angle of attack might reach into the lower two-digit territory, and flow disturbances must be avoided especially in this phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the fuselage should be &lt;a href=&quot;https://aviation.stackexchange.com/questions/2726/why-do-airliners-pitch-up-during-cruise/2797#2797&quot;&gt;horizontal during cruise&lt;/a&gt; to avoid making the work of the cabin personnel harder than it already is. A few degrees of intake misalignment can be tolerated, and the misalignment is usually split between cruise and post-rotation climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With supersonic intakes, things are different: They are much more sensitive to misalignments, and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet&quot;&gt;intakes of planes like the SR-71&lt;/a&gt; have been carefully optimized for their cruise condition.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-23T20:03:53.260" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16191" PostTypeId="2" ParentId="16185" CreationDate="2015-06-23T15:54:20.797" Score="6" Body="&lt;p&gt;In general, towing requires an aircraft capable of safe operation at low speeds, e.g. a low stall speed, since the drag of the banner makes it difficult to reach higher speeds. Good low speed handling also makes banner pick-up and drop-off operations safer and easier. &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/faa-fs.pdf&quot; rel=&quot;noreferrer&quot;&gt;You can see the FAA's manual on towing operations here (PDF).&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not just airplanes that tow banners.  I worked with a helicopter pilot who used to fly &quot;helibanners.&quot;  The advantage is that a very large banner can be towed since the helicopter can handle gusts &quot;dragging&quot; the helicopter down to very low flight speeds and the rotor can provide considerable thrust at low speeds.  The new hazard is that the banner and its rigging can get caught in the tail rotor, which would be catastrophic.  This is usually dealt with by using a special weighted banner design that keeps everything away from the empennage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vG05s.jpg&quot; alt=&quot;Chase Helibanner&quot;&gt;&lt;br&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://aerial-media.com&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="9015" LastEditorUserId="65" LastEditDate="2015-06-23T16:16:05.377" LastActivityDate="2015-06-23T16:16:05.377" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16193" PostTypeId="1" AcceptedAnswerId="16202" CreationDate="2015-06-23T16:29:59.353" Score="57" ViewCount="36485" Body="&lt;p&gt;Just the basic question that every aviation enthusiast must be curious about: exactly how does a wing generate lift?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="8818" LastEditDate="2015-06-23T19:04:40.953" LastActivityDate="2020-07-04T17:36:05.600" Title="How do wings generate lift?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;lift&gt;&lt;fluid-mechanics&gt;" AnswerCount="11" CommentCount="18" FavoriteCount="25" ContentLicense="CC BY-SA 3.0" />
  <row Id="16196" PostTypeId="2" ParentId="16193" CreationDate="2015-06-23T16:56:24.077" Score="-3" Body="&lt;p&gt;Lift is a force generated across a wing because of &lt;strong&gt;Pressure Difference&lt;/strong&gt;. So,basically If you are able to achieve different pressure above and below a wing, you'd have lift. Now, from basic Newton's law, this force would be directed from the region of high pressure to the region of low pressure (Because the region of high pressure is going to push the surface by exerting more force onto it as compared to the region of low pressure which would push the surface with a relatively lesser force).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the important thing is to create this pressure difference. This is achieved by exploiting an interesting property of fluid : A fast flowing fluid has lower pressure as compared to a slow moving fluid. This property can be &lt;strong&gt;proved&lt;/strong&gt; by various mathematical means and is beautifully incorporated in the &lt;strong&gt;Bernoulli's Principle&lt;/strong&gt;. Hence &lt;strong&gt;Bernoulli's Principle&lt;/strong&gt; is a mathematical expression of an inherent property of a fluid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to get lift, the required pressure difference can be created by having a flow around the airfoil in such a way that the velocities of fluid below and above the airfoil are different. This is achieved by changing the shape of the wing (Camber) in such a way that it becomes asymmetrical. The asymmetry causes different velocities on the top and bottom portion of the airfoil because of the following reason:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a fluid reaches the Leading Edge of the airfoil, some part of the fluid is displaced upwards, while some of it is displaced downwards. Due to the asymmetry of the Airfoil, the fluid which has moved upwards has less cross sectional area to move through as compared to the fluid which went under the airfoil. This difference in area available to the fluid for movement creates the difference in the speeds of the fluid in different regions. This property of fluid to move faster in areas of lesser cross section, and move slowly in areas of larger cross section can be derived in mathematical form by application of conservation of mass, and is called &lt;strong&gt;Principle of Continuity&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, changed fluid velocities create a pressure gradient which in turn causes a force on the wing, which is called lift. Now, this lift can be in any direction (which could be found out by integrating very small forces on very small areas on the wing surface). The component of this force &lt;strong&gt;perpendicular&lt;/strong&gt; to the direction of the velocity of the aircraft is called &lt;strong&gt;lift&lt;/strong&gt; force, where as the other component &lt;strong&gt;parallel&lt;/strong&gt; to the velocity of the airplane is then included in the &lt;strong&gt;drag&lt;/strong&gt; force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For very accurate representation of the equations governing fluid behavior, it can be argued that Bernoulli's Principle is incorrect. In this case Navier Stoke's equation is valid, but for understanding purposes, any &lt;strong&gt;time invariant (steady), in compressible, inviscid&lt;/strong&gt; flow can be considered to obey Bernoulli's Equation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, for a real fluid, it would not obey Bernoulli's Equation most of the times, but the general behavior of the pressure reduction with flow speed increase is still observed, though exact pressure drop can not be calculated through Bernoulli's Equation. In such cases Navier Stoke's equation is used to correctly calculate the pressure drop created due to increased velocity of the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 2&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For symmetrical wings, the wing wont generate any lift if the flow see's the wing symmetrically, so that inherently means that a symmetrical wing with 0 angle of attact would not produce any lift. To get lift from a symmetrical wing, it is placed at some angle to the flow, so that the flow see's it &quot;asymmetrically&quot; and hence, the above explanation can be used to explain the life generated in this case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 3&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Explanation for Planes flying upside down: For a normal plane to fly, a positive angle of attack is needed. Give this plane a velocity axis roll of 180 degrees, you get a plane with -ve angle of attack, and hence a negative lift. But a plane cannot sustain flight with negative lift, so what the upside down flying planes need to do is to increase the -ve angle of attack to positive, by pulling the nose up (that would be pushing the nose towards the sky in an upside down plane). This causes the angle of attack to change and become +ve. The +ve angle of attack means that the wing will now experience a life such that a upside down plane has lift in upwards direction (This is equivalent to a normal plane with - ve angle of attack and hence negative lift). &lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-24T04:39:17.853" LastActivityDate="2015-06-24T04:39:17.853" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16197" PostTypeId="2" ParentId="8118" CreationDate="2015-06-23T17:57:30.483" Score="7" Body="&lt;p&gt;I was recently PIC of a twin Aztec,  when I was on a single pilot IFR departure. At about 800 feet at gross weight, without warning there was a loud bang and the right engine quit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was able to make a wide left 270 tear drop turn into the good engine which was operating at full power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My multi-engine training taught me the skills necessary to survive this failure. A turn in to the good engine is taught for a reason. Raise the dead... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This helps the rudder have the authority to over power the asymmetrical thrust of the good engine. I believe a turn into the dead engine may have resulted in loss of control, and death. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main thing is DON'T PANIC... Fly the airplane...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The good Lord was in control as The aircraft was loaded at gross weight (5 passengers and baggage). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was able to complete the turn and land safely opposite the direction of my departure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall horn was chirping through out the shallow turn, but my airspeed was right at Vyse (blue line). We were NOT climbing. The cause of the failure has not yet been diagnosed.&lt;/p&gt;&#xA;" OwnerUserId="9026" LastActivityDate="2015-06-23T17:57:30.483" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16198" PostTypeId="2" ParentId="16193" CreationDate="2015-06-23T18:52:31.637" Score="34" Body="&lt;p&gt;Short answer: by exerting a downward force on the air around them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: Some outreach people at NASA's Glenn Research Center have written up a very good multi-page explanation, dealing individually with each contributing effect, as well as some discussion of why explanations you might have heard at school don't work. Since the navigation there is a bit funky, I'll link each page individually with a short summary.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/right1.html&quot;&gt;Lift from Pressure-Area&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When a fluid moves over an object (or vice-versa), the pressure is different at different points. Because of this pressure difference, there's an overall force. You can use the Bernoulli equation to work out this force, but you need to know the speed of the fluid (at each point on the wing) to start. You can't just explain it with &quot;the Bernoulli effect&quot;, because the Bernoulli effect applies just as much to anything moving through the air.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/right2.html&quot;&gt;Lift from Flow Turning&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Both surfaces of the wing turn the flow of air. The bottom surface deflects it (the air bounces off the wing), while the curved top surface bends it around (the air sticks to the wing). The turning of the flow is what gives you lift rather than just drag. You can look at the turning as the source of the pressure difference in the Bernoulli effect, or you can think of it simply in terms of equal and opposite forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's another way of modelling the flow turning, which isn't discussed on the NASA site. If you've heard of the Kutta-Joukowski theorem, this is what it relates to. When the air bends around the wing (or any object), there are two special points. At the front of the wing, some of the air goes over the top, and some goes under the bottom, but there's a point in between the two. The opposite situation happens at the back of the wing, where the air from the top surface meets the air that came the bottom way (but not the 'same' air: see wrong theory #1 below). These two points are called &lt;em&gt;stagnation points&lt;/em&gt;. In a normal object, they're at the same level vertically each other, but &lt;a href=&quot;https://en.wikipedia.org/wiki/Kutta_condition&quot;&gt;because the back of a wing is sharp&lt;/a&gt;, the rear stagnation point will form behind it when the wing is moving quickly enough. That's lower than the front stagnation point, which implies that the net movement of air is downwards. That's where the flow turning comes from, and the theorem lets you calculate how much lift you get.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html&quot;&gt;Wrong Theory #1: Equal transit time&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As I said, to invoke the Bernoulli effect, you have to explain why the air on the upper surface is moving faster. Teachers often claim that it's because the air on the top surface has to meet the air on the bottom surface. That's simply wrong, and there's a nice simulator to demonstrate it.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/wrong2.html&quot;&gt;Wrong Theory #2: Skipping stone&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This page discusses when people realise the air &quot;bounces off&quot; the bottom surface of the wing, but neglect the top surface.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/wrong3.html&quot;&gt;Wrong Theory #3: Venturi&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some people imagine the top surface of the wing as a half of a Venturi nozzle (a nozzle which speeds up fluid flow by constricting it). This speed difference would give rise to a pressure difference (Bernoulli effect again), but it turns out the wing doesn't work like a nozzle at all.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html&quot;&gt;Bernoulli and Newton&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This last page just sums up that the wrong theories start with well-known physics (Newton's laws or the Bernoulli effect), but then try to oversimplify everything to make them fit the situation, so they end up with explanations which make wrong predictions.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-06-23T18:52:31.637" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="16199" PostTypeId="1" AcceptedAnswerId="16200" CreationDate="2015-06-23T19:43:57.927" Score="18" ViewCount="17103" Body="&lt;p&gt;How do large airliners de-ice their surfaces in midair? In smaller planes like the ATR or the caravan there are deicing boots as per picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Oji6p.jpg&quot; alt=&quot;deicing boot&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this achieved on bigger aircraft, as there seems to be no such mechanism?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="923" LastEditDate="2015-06-23T19:54:45.707" LastActivityDate="2018-05-09T19:15:02.593" Title="How do large airliners de-ice in flight?" Tags="&lt;icing&gt;&lt;anti-ice&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16200" PostTypeId="2" ParentId="16199" CreationDate="2015-06-23T19:58:57.500" Score="20" Body="&lt;p&gt;Hot bleed air is drawn from the engines and directed through control valves and ducting to the leading edges of the wings and stabilizers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what it looks like on a 727. Note that the upper VHF antenna is also anti-iced to prevent ice entering the engine inlets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zQGCO.png&quot; alt=&quot;727 ATA 30&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787 uses electric heating elements for the wing instead of bleed air from the engines. Engine anti-ice is still done using engine bleed air.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="2341" LastEditDate="2015-06-23T20:04:22.113" LastActivityDate="2015-06-23T20:04:22.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16201" PostTypeId="2" ParentId="16199" CreationDate="2015-06-23T20:03:04.050" Score="10" Body="&lt;p&gt;Apart from pumping hot air, there are a few ways to achieve wing's leading edge de-icing. Most reliable is through electric heaters just beneath the wing surface. &#xA;Other are more tricky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One solution is an elastic leading edge, which can be pushed out by, for example, a linear hydraulic motor. If the ice thickness is just right, it will crumble and fall off. If it is too thin, it will deflect beyond the reach of the mechanism, and of course if it is too thick then nothing can be done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other wings adapt a series of small holes in a leading edge surface, through which a liquid can be pumped, called a &lt;a href=&quot;http://www.boldmethod.com/learn-to-fly/systems/how-weeping-wings-work/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;weeping wing&quot;&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Ice_protection_system#TKS_Ice_Protection&quot; rel=&quot;nofollow noreferrer&quot;&gt;TKS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I heard there also are mechanisms which adapted vibrations, but I can give no source on this one right now.&lt;/p&gt;&#xA;" OwnerUserId="8994" LastEditorUserId="-1" LastEditDate="2018-05-09T19:15:02.593" LastActivityDate="2018-05-09T19:15:02.593" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="16202" PostTypeId="2" ParentId="16193" CreationDate="2015-06-23T20:15:17.220" Score="46" Body="&lt;p&gt;To get to the bottom of it, it might help to look at lift at a molecular level:&lt;/p&gt;&#xA;&lt;p&gt;Every air molecule is in a dynamic equilibrium between inertial, pressure and viscous effects:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Inertial means that the mass of the particle wants to travel on as before and needs force to be convinced otherwise.&lt;/li&gt;&#xA;&lt;li&gt;Pressure means that air particles oscillate all the time and bounce into other air particles. The more bouncing, the more force they exert on their surroundings.&lt;/li&gt;&#xA;&lt;li&gt;Viscosity means that air molecules, because of this oscillation, tend to assume the speed and direction of their neighbors.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h2&gt;Flow over the upper side of the wing&lt;/h2&gt;&#xA;&lt;p&gt;Now to the airflow: When a wing approaches at subsonic speed, the low pressure area over its upper surface will suck in air ahead of it. See it this way: Above and downstream of a packet of air we have less bouncing of molecules (= less pressure), and now the undiminished bouncing of the air below and upstream of that packet will push its air molecules upwards and towards that wing. The packet of air will rise and accelerate towards the wing and be sucked into that low pressure area. Due to the acceleration, the packet will be stretched lengthwise and its pressure drops in sync with it picking up speed. Spreading happens in flow direction - the packet is distorted and stretched lengthwise, but contracts in the direction orthogonally to the flow. This contraction is needed to make space for that wing; in supersonic flow &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430#57430&quot;&gt;it will decelerate&lt;/a&gt; for the same purpose. Once there, it will &amp;quot;see&amp;quot; that the wing below it curves away from its path of travel, and if that path would remain unchanged, a vacuum between the wing and our packet of air would form. Reluctantly, the packet will change course and follow the wing's contour. This requires even lower pressure, to make the molecules change their direction. This fast-flowing, low-pressure air will in turn suck in new air ahead and below of it, will go on to decelerate and regain its old pressure over the rear half of the wing, and will flow off with its new flow direction.&lt;/p&gt;&#xA;&lt;p&gt;Note that lift can only happen if the upper contour of the wing will slope downwards and away from the initial path of the air flowing around the wing's leading edge. This could either be camber or angle of attack - both will have the same effect. Since camber allows for a gradual change of the contour, it is more efficient than angle of attack.&lt;/p&gt;&#xA;&lt;h2&gt;Flow over the lower side of the wing&lt;/h2&gt;&#xA;&lt;p&gt;A packet of air which ends up below the wing will experience less uplift and acceleration, and in the convex part of highly cambered airfoils it will experience a compression. It also has to change its flow path, because the cambered and/or inclined wing will push the air below it downwards, creating more pressure and more bouncing from above for our packet below the wing. When both packets arrive at the trailing edge, they will have picked up some downward speed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V7Ujo.png&quot; alt=&quot;Airfoil in wind tunnel with smoke trails indicating flow&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Behind the wing, both packets will continue along their downward path for a while due to inertia and push other air below them down and sideways. Above them, this air, having been pushed sideways before, will now fill the space above our two packets. Macroscopically, this looks like two big vortices. But the air in these vortices cannot act on the wing anymore, so it will not affect drag or lift. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;here for more on that effect&lt;/a&gt;, including pretty pictures.&lt;/p&gt;&#xA;&lt;h2&gt;Lift can be explained in several, equivalent ways&lt;/h2&gt;&#xA;&lt;p&gt;Following the picture of a pressure field outlined above, lift is the difference of pressure between upper and lower surface of the wing. The molecules will bounce against the wing skin more at the lower side than at the upper side, and the difference is lift.&lt;/p&gt;&#xA;&lt;p&gt;Or you look at the macroscopic picture: A certain mass of air has been accelerated downwards by the wing, and this required a force to act on that air. This force is what keeps the aircraft up in the air: Lift.&lt;/p&gt;&#xA;&lt;p&gt;If you look at the wing as a black box and only pay attention to the impulse of the inflowing and outflowing air, the wing will change the impulse by adding a downward component. The reaction force of this impulse change is lift.&lt;/p&gt;&#xA;&lt;p&gt;Either way, you will arrive at the same result. By the way: Most of the directional change happens in the forward part of the airfoil, not at the trailing edge!&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AGhZF.png&quot; alt=&quot;streamlines around a wing and direction of impulses&quot; /&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Lift is a matter of definition&lt;/h2&gt;&#xA;&lt;p&gt;Lift and induced drag are both part of the pressures acting on the wing. If you add up all the pressure forces acting on a wing, their resulting vector will point slightly backwards. The streamwise component is drag, and the component orthogonal to the direction of movement is lift. This is just a defininion, made for simplicity.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-07-04T17:36:05.600" LastActivityDate="2020-07-04T17:36:05.600" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="16203" PostTypeId="2" ParentId="16022" CreationDate="2015-06-23T20:24:18.073" Score="3" Body="&lt;p&gt;There is no straight answer or a formula for this one. In real life you first think of what you want to fit inside the fuselage and then design the rest of the plane. For airliners that would be space for passengers and luggage as well. Different fuselage shapes come straight in line from the requirements that the airplane is supposed to meet. Antonov has the shape you described, because it needs a lot of space inside and should stay low to the ground, so it's wings are mounted on top. It also has a huge weight, so a strong set of wheels is required - hence the shape at the bottom (to create enough space for the landing gear to hide without taking the loading space) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from functional requirements, designing a fuselage must take many different aspects into consideration (starting from the most important - but of course the hierarchy depends on many factors):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;mass&lt;/li&gt;&#xA;&lt;li&gt;drag - the frontal area is not all, it is also the nose shape, wing connection and overal area wchich results in friction loses&lt;/li&gt;&#xA;&lt;li&gt;stress caused by wing's lift and drag, momentums of wing and stabilizers and pressure difference&lt;/li&gt;&#xA;&lt;li&gt;fatigue safety&lt;/li&gt;&#xA;&lt;li&gt;doors, windows, landing gear&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8994" LastActivityDate="2015-06-23T20:24:18.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16205" PostTypeId="1" AcceptedAnswerId="16214" CreationDate="2015-06-23T21:16:00.097" Score="23" ViewCount="18002" Body="&lt;p&gt;Airports in the United States are (mostly) three letters, prefixed with a &lt;code&gt;K&lt;/code&gt;. Where did this standard originate? Why K?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is similar to &quot;where did the U.S. N registration letter come from&quot;, but different!&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-06-24T06:18:23.727" Title="Where did the &quot;K&quot; identifier prefix for US airports come from?" Tags="&lt;airport&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16206" PostTypeId="1" AcceptedAnswerId="16207" CreationDate="2015-06-23T21:43:56.513" Score="8" ViewCount="1726" Body="&lt;p&gt;Some turboprop aircraft, for example &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter&quot;&gt;DHC 6 Twin Otter&lt;/a&gt; have “intake deflectors” which should be engaged when taking off from or landing on unpaved surface to prevent foreign object damage. But how does it actually work?&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-06-23T21:57:58.940" Title="How do intake deflectors work?" Tags="&lt;turboprop&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16207" PostTypeId="2" ParentId="16206" CreationDate="2015-06-23T21:57:58.940" Score="11" Body="&lt;p&gt;This &lt;a href=&quot;https://www.pwc.ca/files/en/Know_your_PT6A.pdf&quot; rel=&quot;noreferrer&quot;&gt;document&lt;/a&gt; describes it nicely. They are also known as inertial seperators:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The nacelle inlet of many aircraft models includes an inertial separator &#xA;  provided by the aircraft manufacturer to prevent heavy particles from &#xA;  entering the engine inlet. Most installations incorporate two moveable &#xA;  vanes, one upstream of the engine inlet and the other blocking the bypass &#xA;  duct. For bypass operation, the inlet vane is lowered and the bypass &#xA;  duct vane is opened permitting maximum separating efficiency. In some &#xA;  installations, the vanes are fixed in the bypass mode. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;As shown in the sketch, air entering the engine inlet must turn sharply past the inlet vane (shown in the lowered position). Particles heavier than air are carried straight through, by their own inertia, into the bypass duct and dumped overboard.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The aft radial inlet design provides many advantages such as superior &#xA;  anti-icing utilizing the principle of inertial separation, low noise levels and unequalled protection from FOD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/heVKG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-06-23T21:57:58.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16209" PostTypeId="2" ParentId="16199" CreationDate="2015-06-24T03:46:50.140" Score="22" Body="&lt;p&gt;Putting this as an answer rather than a comment because of its length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In response to @romkyns comment, perhaps the 787 pilot knew of the heating elements within the wing but was simply telling how ice was normally handled. I really can't imagine him getting through his type rating oral without knowing that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Had you asked me the same question back when I was flying 747-100 and -200 aircraft, I would have replied thus:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Icing isn't typically a problem because you're usually not in it long enough at a slow enough speed that the ram air temperature rise doesn't get the temperature above freezing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are getting ice on climb out at your normal climb speed, it was usual to ignore it knowing that the icing would soon stop as you gained altitude, and then what icing you had would soon sublimate. If the icing was severe enough to warrant your attention, the usual remedy was to just speed up to get more ram air temperature rise, but you would, of course, be sacrificing some of your climb rate. The U.S. has a 250kt speed limit below 10,000 feet, but you don't have to (or at least didn't have to back then) observe that if there was an operational need to go faster, and generating enough heat to take care of icing was considered a good reason. You normally wouldn't have to think about that though because a 747 climbing out with flaps up has a minimum safe airspeed in excess of 250 anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One indication that the icing was serious was that ice buildup on the windshield wipers would set them to vibrating and giving off a loud buzzing sound. If you let them do that too long, they could depart the aircraft. As I understood it, the time for that to happen was cumulative over the past occurrences as well as the current occurrence, as it was a matter of fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were icing on the approach and didn't want to or couldn't speed up, you could heat the wing leading edge with pneumatic air as described in previous answers. However, it was the leading edge slats that were heated, and when you selected the first notch of flaps, that deployed the leading edge slats, and the heated pneumatic air escaped with little or no effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only once in 10 years of 747 flying did I use the leading edge heating. We were in a holding pattern at low altitude waiting for our turn for an approach into Brussels.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1696" LastEditDate="2015-06-24T16:45:15.790" LastActivityDate="2015-06-24T16:45:15.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16210" PostTypeId="1" CreationDate="2015-06-24T03:59:45.020" Score="2" ViewCount="355" Body="&lt;p&gt;My question, would a multi-deployment airframe parachute system be viable on a commercial airline? For example, Grumman &amp;amp; Cirrus already use this system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with the automobile industries, they were found to be culpable of many road deaths prior to implementation of seatbelts (refused by all the automakers at the time), so is it the airlines' responsibility for not making flight safe enough when the technology is there to implement?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot buy a new car without it having airbags, why not airframe parachute on every new plane as a standard?&lt;/p&gt;&#xA;" OwnerUserId="9033" LastEditorUserId="3956" LastEditDate="2015-06-24T04:22:35.170" LastActivityDate="2015-06-24T04:50:04.610" Title="Airframe parachute on commercial airlines" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;airframe-parachute&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-06-24T05:45:15.660" ContentLicense="CC BY-SA 3.0" />
  <row Id="16211" PostTypeId="2" ParentId="16210" CreationDate="2015-06-24T04:50:04.610" Score="0" Body="&lt;ol&gt;&#xA;&lt;li&gt;Cirrus builds very small planes that fly at a very low altitude and at very small speeds, hence the parachutes (CAPS) can be used.&lt;/li&gt;&#xA;&lt;li&gt;General aviation aircraft are HUGE, BULKY and designed to fly at very high mach numbers. They are not designed to &quot;withhold spin&quot; as required by the CAPS. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Moreover, if this was possible, this would already be in action, because an Automobile accident is not much of a Headache for auto companies, but an Aviation disaster is for sure a PR nightmare for an Aviation Company.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-06-24T04:50:04.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16212" PostTypeId="2" ParentId="16162" CreationDate="2015-06-24T05:05:46.597" Score="6" Body="&lt;p&gt;Basically, for the same gross mass, a rotorcraft requires considerably more power than a fixed-wing. This is due to the fact that fixed wing aircraft propulsion system needs to create thrust that is equal to the drag of the complete aircraft, and the weight of the aircraft is lifted by the wing-lift force (which is usually 10 or 20 times higher than drag); whereas the rotor of a rotorcraft needs to create thrust that is equal to the total weight of the rotorcraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if both aircraft have the same engine efficiencies, the helicopter fuel-consumption rate (liters per hour) would be considerably more. So, theoritecally helicopters are not comparable to the efficiency of fixed-wing.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastEditorUserId="8079" LastEditDate="2015-06-26T05:18:49.497" LastActivityDate="2015-06-26T05:18:49.497" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16213" PostTypeId="2" ParentId="16193" CreationDate="2015-06-24T05:27:42.480" Score="4" Body="&lt;p&gt;A simple way to understand it is that the wing acts as a blade in a fan. Moving through the air at the correct angle causes a vacuum to form on top. The front tip must be round to allow the air to move smoothly and expand to create the vacuum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flat bottoms and other shapes are simply maximizing this effect but are not necessary. This is why it is possible to fly upside-down as long as the wing is hitting the air at the right angle. (Not at a right-angle.) &lt;/p&gt;&#xA;" OwnerUserId="9034" LastActivityDate="2015-06-24T05:27:42.480" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16214" PostTypeId="2" ParentId="16205" CreationDate="2015-06-24T06:18:23.727" Score="20" Body="&lt;p&gt;The letter &lt;code&gt;K&lt;/code&gt; was simply assigned to the contiguous US by ICAO, in order to have a system with unique identifiers for world-wide use, instead of trying to adapt local system to match. The IATA codes had been in use already and possible duplicates could not be excluded. The &lt;code&gt;K&lt;/code&gt; in US ICAO codes is there to mark the region the codes is in, see the chart below.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jyHxi.png&quot; alt=&quot;Assigned of ICAO codes&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;A good summary of how many of the airport codes have been created can be found on &lt;a href=&quot;http://www.skygod.com/asstd/abc.html&quot; rel=&quot;noreferrer&quot;&gt;www.skygod.com&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Airlines use the three-letter codes internationally in their own network, Sita, for messages such as passenger loads and departure times. World ATC and weather agencies use a separate teleprinter network, the Aeronautical Fixed Telecommunications Network (AFTN), which uses a four-letter &amp;quot;location indicator.&amp;quot; Going from large area to actual airport, the first letter relates to the part of the world and the second letter the country. The third letter is a group of airports within that country. Most countries who use this particular convention use a letter to denote the FIR in which the airport is located. So F is Frankfurt FIR in Germany, M is Munich; P is Paris FIR, M is Marseilles. Other ways to use the third letter include identifying a group of airports with a common factor. For example, A was used in Germany for all Canadian and American air force bases. The last letter positively identifies a specific airport.&lt;/p&gt;&#xA;&lt;p&gt;Thus Aberdeen, Scotland, has the International Civil Aviation Organization (ICAO) location indicator of EGPD—E for Northern Europe, G for United Kingdom, P for Scottish region, and D for Dyce field. Want to figure out LFPG? It's L for southern Europe, F for France, P for Paris FIR, and G for Charles de Gaulle airport. Easy!  Some are more easy to remember. The Dominican Republic codes all start with M (Central America) and D (Dominican) and then, well, see if you spot the code for international airports in Santo Domingo (MDSD), La Romana (MDLR), Puerto Plata (MDPP), Punta Cana (MDPC) and Santiago (MDST).&lt;/p&gt;&#xA;&lt;p&gt;So if London Heathrow has two codes — and it does, LHR and EGLL — how come I've heard Chicago O'Hare only called ORD? The answer is unique to the United States and Canada. In the 48 contiguous States the ICAO code is formed simply by adding a &amp;quot;K&amp;quot; to the three letter code (or by adding a &amp;quot;C&amp;quot; in Canada). This explains why international flight plans refer to KORD, KMIA, KJFK, etc. A meeting of two rules is Key West, the FAA code is EYW (lose the 'K') and the IATA code is KEYW (add a 'K') which works great for KEY West.&lt;/p&gt;&#xA;&lt;p&gt;Other airports within FAA jurisdiction have ICAO codes usually formed by taking two letters from the FAA name and prefixing them with PA for Alaska, PH for Hawaii, or PG for Guam. PT appears to be Pacific Trust Territories (Pohnpei, Yap, Chuuk, etc.), and there are various random other P codes like PWAK for Wake Island.&lt;/p&gt;&#xA;&lt;p&gt;While most U.S. airports have the same three-letter location identifier for the FAA and IATA, note I didn't say all do. Scenic Sedona Airport in Arizona is assigned SEZ by the FAA and SDX by the IATA. Because for international airlines SEZ is Seychelles International Airport in Mah�, Seychelles. Another is the Hilton Head airport in South Carolina mentioned earlier. It's IATA code is HHH, but it's FAA three letter code is HXD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Related question:&lt;br /&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/8699/572&quot;&gt;What is the methodology for assigning airport codes?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-24T06:18:23.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16215" PostTypeId="1" AcceptedAnswerId="16227" CreationDate="2015-06-24T06:53:51.237" Score="18" ViewCount="9476" Body="&lt;p&gt;Cruise missiles and ballistic missiles are used by many nations as offensive and defensive technology. How do cruise missiles and ballistic missiles maneuver, and what are the differences between the basic principles of these maneuvers?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="572" LastEditDate="2015-06-24T12:37:17.093" LastActivityDate="2016-09-23T04:51:04.337" Title="How are cruise missiles different from ballistic missiles?" Tags="&lt;missiles&gt;&lt;control-surfaces&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16216" PostTypeId="1" AcceptedAnswerId="16217" CreationDate="2015-06-24T07:48:25.847" Score="7" ViewCount="5688" Body="&lt;p&gt;When and in what scenario is the SELCAL (Selective Calling Radio System)  check being performed by crew?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="572" LastEditDate="2015-06-24T07:50:20.250" LastActivityDate="2015-06-24T08:01:00.707" Title="When and why is the SELCAL (Selective Calling Radio System) check being performed?" Tags="&lt;radio-communications&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16217" PostTypeId="2" ParentId="16216" CreationDate="2015-06-24T08:01:00.707" Score="8" Body="&lt;p&gt;If you are unsure whether your SELCAL equipment is properly working, you can request a &lt;code&gt;SELCAL check&lt;/code&gt; on a HF-enabled radio frequency. The ATC unit will send out your SELCAL code for testing purposes.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;I'm not sure my selcal unit is working, is there anywhere I can test it?&lt;/p&gt;&#xA;&lt;p&gt;Yes, several places.  If you are located in:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Europe or east of 30W on the North Atlantic, call Stockholm Radio&lt;/li&gt;&#xA;&lt;li&gt;Eastern USA/Canada or west of 30W on the North Atlantic, call New York ARINC&lt;/li&gt;&#xA;&lt;li&gt;Western USA/Canada or Pacific, call San Francisco ARINC&lt;/li&gt;&#xA;&lt;li&gt;Asia - daylight hours, call Singapore or Manila Radio on 8942 KHz USB&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;[...] All selcal checks are free of charge - just call the station with the aircraft registration mark and when you receive a reply ask for a selcal check and give your selcal code.  The operator will send out your selcal tone and - assuming the selcal unit is working - you will hear a chime in the cockpit.  Acknowledge by replying 'selcal check okay' and you're done!   If your selcal check doesn't work the first time it is worthwhile asking for a 'double' which means you get 2 sets of tones sent out back-to-back and often cures any issues.&lt;br /&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.selcalweb.co.uk/faq.html#11&quot; rel=&quot;noreferrer&quot;&gt;www.selcalweb.co.uk&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-24T08:01:00.707" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16218" PostTypeId="2" ParentId="16215" CreationDate="2015-06-24T08:36:42.203" Score="13" Body="&lt;p&gt;Cruise missiles have rocket or jet engines that are powered during the entire flight. It allows the missile to cruise low through the atmosphere, sometimes just above ground level. Lift and guidance of the missile are achieved by aerodynamic forces.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ballistic missiles on the other hand are not powered during most of their flight. During the launch they are given a high initial velocity and then coast throughout most of their flight. Their flight path is by approximation parabolic. Ballistic missiles are guided during brief periods of their flight, aerodynamically and/or by thrust vectoring. Intercontinental Ballistic missiles go into a suborbital paths and spend a considerable part of their trajectory outside the atmosphere. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1961" LastEditDate="2015-06-24T10:44:17.260" LastActivityDate="2015-06-24T10:44:17.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16219" PostTypeId="2" ParentId="16215" CreationDate="2015-06-24T08:39:46.860" Score="32" Body="&lt;p&gt;A cruise missile is rocket or jet powered and flies to its target within the atmosphere, using lift to stay up. Most have wings, although a few may use lifting body designs. They maneuver using control surfaces on the wings and tail like an airplane. Mission profiles can include big course changes, to evade air defenses, or to hug terrain to stay hidden. They can be launched from fixed ground positions but most are launched from mobile platforms. They tend to have shorter ranges than ballistic missiles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A ballistic missile is a rocket that powers its way out of the atmosphere and coasts in an arc, re-entering the atmosphere before hitting its target. They have little maneuvering capability, once the boost phase is done it's all down to physics. Some warheads are able to maneuver a bit in re-entry in order to hit a pinpoint target, others are just rocks at that point. The largest ones are launched from fixed positions like missile silos but smaller ones are mobile. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-06-24T08:50:02.327" LastActivityDate="2015-06-24T08:50:02.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16220" PostTypeId="1" AcceptedAnswerId="16237" CreationDate="2015-06-24T09:11:25.760" Score="3" ViewCount="507" Body="&lt;p&gt;Wing mounted jet engines face the free stream at Mach number 1 or above, and they work perfectly for Mach numbers below 1 as well, even though the free stream characteristics change a lot after Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How do the engines manage to work despite the fact that after Mach 1, the Shock waves would try and disrupt the normal airflow?&lt;/li&gt;&#xA;&lt;li&gt;If the engines are optimized to work at above Mach 1, does this cause any trouble for them to work under subsonic conditions?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Don't confuse with &quot;Why cant jet engines work with supersonic flow?&quot;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-24T20:10:29.543" LastActivityDate="2015-06-24T20:10:29.543" Title="How does a wing mounted jet engine on a supersonic airplane prevent the interference in the flow due to Shock?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;shock-waves&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-06-24T21:04:15.680" ContentLicense="CC BY-SA 3.0" />
  <row Id="16221" PostTypeId="5" CreationDate="2015-06-24T09:12:54.390" Score="0" Body="&lt;p&gt;A shock wave is a type of propagating disturbance. When a wave moves faster than the speed of sound in a liquid, gas or plasma (a &quot;fluid&quot;, in physics terminology) it is a shock wave. Like an ordinary wave, a shock wave carries energy, and can propagate through a medium. It is characterized by an abrupt, nearly discontinuous change in pressure, temperature and density of the medium. In supersonic flows, expansion is achieved through an expansion fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike solitons (another kind of nonlinear wave), the energy of a shock wave dissipates relatively quickly with distance. Also, the accompanying expansion wave approaches and eventually merges with the shock wave, partially cancelling it out. Thus the sonic boom associated with the passage of a supersonic aircraft is the sound wave resulting from the degradation and merging of the shock wave and the expansion wave produced by the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a shock wave passes through matter, the total energy is preserved but the energy which can be extracted as work decreases and the entropy increases. This, for example, creates additional drag force on aircraft with shocks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shock waves can travel through any medium, including solids, liquids, gasses, and plasmas.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-24T09:40:54.443" LastActivityDate="2015-06-24T09:40:54.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16222" PostTypeId="4" CreationDate="2015-06-24T09:12:54.390" Score="0" Body="A shock wave is a type of propagating disturbance. When a wave moves faster than the speed of sound in a liquid, gas or plasma (a &quot;fluid&quot;, in physics terminology) it is a shock wave. Like an ordinary wave, a shock wave carries energy, and can propagate through a medium. It is characterized by an abrupt, nearly discontinuous change in pressure, temperature and density of the medium. In supersonic flows, expansion is achieved through an expansion fan." OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-06-24T09:40:50.263" LastActivityDate="2015-06-24T09:40:50.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16223" PostTypeId="2" ParentId="13522" CreationDate="2015-06-24T09:28:56.163" Score="1" Body="&lt;p&gt;For a supersonic plane, a convergent nozzle with &lt;strong&gt;decelerate&lt;/strong&gt; the flow. This is required only at the &lt;strong&gt;compressor&lt;/strong&gt;, where flow velocity should be slower, but after that to get more thrust, the flow needs to be &lt;strong&gt;accelerated&lt;/strong&gt; .&lt;/p&gt;&#xA;&lt;p&gt;Now, one can argue that if a supersonic flow enters a converging nozzle, it would accelerate so subsonic speed (at about Mach 1 ) after which the convergent nozzle would accelerate the flow. But this would never achieve any Mach above 1 for the flow, because as soon as the flow tops Mach 1, it would be decelerated by the convergent part of the nozzle once again. So, the &lt;strong&gt;maximum exit Mach&lt;/strong&gt; one could expect to get off a convergent nozzle is &lt;strong&gt;1&lt;/strong&gt; (whether the input is supersonic or subsonic).&lt;/p&gt;&#xA;&lt;p&gt;Now, for supersonic flight, it is &lt;strong&gt;necessary&lt;/strong&gt; that the exit mach number is greater than 1. In such cases, one has to use the Convergent Divergent Nozzle (C-D Nozzle).&lt;/p&gt;&#xA;&lt;p&gt;If some one wishes to build an engine which can accelerate a plane to supersonic velocities with subsonic (or transonic) exhaust velocity, then for sure one can use convergent nozzles &lt;em&gt;only&lt;/em&gt;. &lt;strong&gt;But&lt;/strong&gt;, there is a catch :&lt;/p&gt;&#xA;&lt;p&gt;The thrust equation is:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/M65lP.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Here for an engine in free stream Pe is approximately equal to P0. So for positive thrust, the terms containing Ve and V0 should give a positive answer. So to create an engine where Ve &amp;lt; V0 (because V0 is the free stream velocity which is supersonic, and the Ve is exit velocity which is assumed to be transonic in this case), one has to vent out a lot of Me at a high rate. This will mean that it is technically possible to create an engine which gives supersonic flight at transonic exhaust velocity, but such a configuration is going to cost you a lot of fuel.&lt;/p&gt;&#xA;&lt;p&gt;Now, if you consider that the exit temperature is very high, lets say around 1200k, and lets say input temperature of free steam is about 300k, that means the exhaust velocity can be about &lt;strong&gt;Twice&lt;/strong&gt; the Mach 1 velocity of air at 300k (without being supersonic), i.e. about 630 mps. If you input mach is about 1.2, that tranlate to input freestream velocity of 380 mps (apx). This means your exit has accelerated to 630 mps from 380 mps, just by the means of a convergent nozzle. But this still would require a lot of fuel to be burnt (because the thrust required usually for flying a plane a few thousand kilograms in weight is very high).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Hence, its possible, but at the expense of the efficiency of the aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-24T10:58:18.053" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16224" PostTypeId="1" AcceptedAnswerId="16228" CreationDate="2015-06-24T09:40:35.810" Score="15" ViewCount="7724" Body="&lt;p&gt;During oceanic crossings, there are limited to no terrestrial radio communications available, so I would think that most flight routes are designed to minimize ocean crossing time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which commercial flight route have the longest oceanic crossing?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5517" LastEditDate="2015-06-24T13:09:52.007" LastActivityDate="2020-03-19T03:00:55.310" Title="Which is longest Oceanic crossing for any commercial flight route?" Tags="&lt;commercial-aviation&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16225" PostTypeId="1" AcceptedAnswerId="16229" CreationDate="2015-06-24T09:49:07.830" Score="6" ViewCount="2038" Body="&lt;p&gt;It is being claimed by the Airbus that their new planes offer more sound proofing than those of Boeing, and I myself observed the same. How do airplane manufacturers tackle with the problem of soundproofing the cabin, so as to reduce the noise reaching inside from outside the plane (the engine sounds and the free stream noise)? What proportion of the total aircraft development cost would this be (approximately, say for an Airbus 320 and for Boeing 777)?&lt;/p&gt;&#xA;" OwnerUserId="8814" LastEditorUserId="1696" LastEditDate="2015-06-24T14:37:37.413" LastActivityDate="2018-02-28T08:05:17.873" Title="What do manufacturers do to reduce cabin noise?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;noise&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16226" PostTypeId="1" CreationDate="2015-06-24T09:56:57.147" Score="4" ViewCount="294" Body="&lt;p&gt;Are any Northern Pacific (NOPAC) routes reserved for military use?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2016-01-21T13:21:19.340" LastActivityDate="2016-06-12T20:05:59.400" Title="Are certain NOPAC routes reserved for military use?" Tags="&lt;military&gt;&lt;navigation&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16227" PostTypeId="2" ParentId="16215" CreationDate="2015-06-24T10:03:44.780" Score="23" Body="&lt;p&gt;&lt;strong&gt;Cruise Missile :&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Uses thrust for the whole trajectory&lt;/li&gt;&#xA;&lt;li&gt;Uses aerodynamic forces by moving control surfaces to move. May use thrust vectoring&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Ballistic Missile:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Uses thrust to reach very high altitude. After that, no thrust, only potential energy is used and converted to speed.&lt;/li&gt;&#xA;&lt;li&gt;Uses aerodynamic forces (for a limited extent) to move by deflecting control surfaces.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8814" LastActivityDate="2015-06-24T10:03:44.780" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16228" PostTypeId="2" ParentId="16224" CreationDate="2015-06-24T10:32:27.750" Score="15" Body="&lt;p&gt;For the longest  Oceanic Crossing, the following are the top three contenders:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Sydney to Vancouver&lt;/li&gt;&#xA;&lt;li&gt;Melbourne to Los Angeles&lt;/li&gt;&#xA;&lt;li&gt;Auckland to Vancouver&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Out of this, 1 and 2 pass over a few islands on their way, 3 does not pass over any landmass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a look at this : &lt;a href=&quot;http://www.gcmap.com/mapui?P=mel-lax%0D%0Asyd-yvr%0D%0Aakl-yvr&amp;amp;MS=wls&amp;amp;DU=mi&quot; rel=&quot;noreferrer&quot;&gt;www.gcmap.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h5JzP.png&quot; alt=&quot;GCMAP of flights&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.gcmap.com)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="675" LastEditDate="2015-06-24T19:38:37.040" LastActivityDate="2015-06-24T19:38:37.040" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16229" PostTypeId="2" ParentId="16225" CreationDate="2015-06-24T10:50:02.390" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;it is being claimed by the Airbus that their new planes offer more sound proofing than those of Boeing&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess you mean &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/comfort/quietness/&quot; rel=&quot;noreferrer&quot;&gt;this sort of claim&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No matter where they sit, all passengers benefit from the quiet A380 cabin with &lt;strong&gt;on average half the sound energy of other aircraft&lt;/strong&gt;. Passengers' feedback confirms the extraordinary contribution to their general well-being due to the absence of background noise on the A380.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In market research surveys the A320 is regularly rated higher than its rivals for the low level of noise in its cabin. &lt;strong&gt;Effective insulation in the cabin&lt;/strong&gt; is one reason why passengers say they find the A320 a quiet aircraft in which to fly. The A320 cabin is the subject of continuous improvements and in its latest version, the noise has been reduced by a further 1dB.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;how do Airplane manufacturers tackle the problem of soundproofing the cabin&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are a variety of methods&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;soundproofing materials in the wall of the fuselage between inner and outer skins.&lt;/li&gt;&#xA;&lt;li&gt;choice of interior materials and furnishings etc. &lt;/li&gt;&#xA;&lt;li&gt;adjusting cabin interior contours to allow lower airflow velocity.&lt;/li&gt;&#xA;&lt;li&gt;fuselage aerodynamics.&lt;/li&gt;&#xA;&lt;li&gt;engine nacelle accoustic liners.&lt;/li&gt;&#xA;&lt;li&gt;scalloped edges on engine exhaust nozzle.&lt;/li&gt;&#xA;&lt;li&gt;larger slower engine fans.&lt;/li&gt;&#xA;&lt;li&gt;sharklets.&lt;/li&gt;&#xA;&lt;li&gt;etc&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;BBC &lt;a href=&quot;http://www.bbc.com/future/story/20140226-tricks-for-a-peaceful-flight&quot; rel=&quot;noreferrer&quot;&gt;report&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of the &lt;strong&gt;main sources of noise is wind&lt;/strong&gt;. So during the design phase of modern aircraft, computational tools model the aerodynamics of the aeroplane to highlight areas of high airflow that are likely to increase cabin noise. This allows engineers to reshape their designs, says Alan Pardoe, director of product marketing at Airbus. Such techniques, he says, helped the double-decker Airbus A380 plane to be recognised by the UK Noise Abatement Society as the quietest jet airliner on the market.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airbus &lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/why-the-worlds-biggest-jetliner-is-a-whispering-giant/&quot; rel=&quot;noreferrer&quot;&gt;say&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When it comes to making the A380 one of the quietest aircraft in the sky, it's the small details that count... in fact, more than 3 million of them!&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This is the number of tiny perforations in &lt;strong&gt;acoustic linings&lt;/strong&gt; on the large nacelles that surround and protect the A380’s jet engines.  The acoustic material helps dampen noise created by the airliner’s four turbofan powerplants, ensuring the A380 is a friendly neighbour wherever it operates in the world.&#xA;  The A380’s nacelles are supplied by Aircelle, which has worked closely with Airbus in minimising the jetliner’s noise output during takeoff and landing.  Acoustic panels are applied throughout the engine – from the air inlet to the exhaust nozzle.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Each panel, which is produced from composite material or titanium, is designed to attenuate noise at different frequencies, further improving the soundproofing effect.  Noise-reducing innovations include Aircelle’s 2-degree-of-freedom acoustic panels, which use a stack of two honeycomb composite sandwich layers separated by a porous wall.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;These panels dampen high-frequency noise from the engine turbines.  With much of this noise source successfully dampened by the acoustic treatment, engineers and designers are now focusing their attention on treating other sources of aircraft noise, promising even quieter jetliners for the future.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/airbus-patented-technology-keeps-the-a380-quiet/&quot; rel=&quot;noreferrer&quot;&gt;also this&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Airbus-developed Zero-Splice engine nacelle liner was designed to reduce the noise generated by the jet engines’ large fan, which represents almost &lt;strong&gt;half the noise during both approach and take-off&lt;/strong&gt;. Following extensive studies carried out by Airbus on how to reduce fan noise, it was found that splices used to join the engine nacelle inlet’s acoustic panels generated forward fan noise – which was counter-efficient to the liner’s acoustic treatment. Airbus therefore developed the Zero-Splice nacelle liner as a single 360 deg. piece of composite, which is comparable in size to the diameter of an A320 fuselage. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is, I think, obvious that measures that reduce engine noise on the ground also reduce it in the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also write about how wing sharklets reduce noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd guess there are many other measures and design choices that are introduced to reduce noise.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What proportion of the total aircraft development cost ...&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'd be surprised if Airbus or Boeing make public any breakdown of their development costs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find general breakdowns like the following but I havent found any that break out soundproofing development costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-885j-aircraft-systems-engineering-fall-2004/lecture-notes/pres_willcox.pdf&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sh4YS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-24T13:17:09.433" LastActivityDate="2015-06-24T13:17:09.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16231" PostTypeId="1" CreationDate="2015-06-24T11:49:10.163" Score="12" ViewCount="1350" Body="&lt;p&gt;Circa 1910 airplane with tail number seventy two&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Pr7MG.jpg&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Click for larger view.&quot;&gt;(Click for larger image)&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Pr7MGl.jpg&quot; alt=&quot;Circa 1910 airplane with tail number seventy two&quot; title=&quot;Click for larger view.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9040" LastEditorUserId="19" LastEditDate="2016-07-04T11:27:38.850" LastActivityDate="2019-03-30T21:03:49.667" Title="Can you help me identifying this circa 1910 airplane with tail number 72?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16232" PostTypeId="2" ParentId="16231" CreationDate="2015-06-24T12:13:00.823" Score="5" Body="&lt;p&gt;&lt;strike&gt;Looks very much like a &lt;strong&gt;Wright Model R&lt;/strong&gt;. Some information can be found &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Model_R.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, a picture from that site below:&lt;/strike&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SCLUu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SCLUu.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Wright_Airplane_images/Model%20R/1910_Model_R_Simms_on_display.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wright-brothers.org&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-03-30T21:03:49.667" LastActivityDate="2019-03-30T21:03:49.667" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16233" PostTypeId="1" AcceptedAnswerId="16472" CreationDate="2015-06-24T12:59:46.663" Score="5" ViewCount="1227" Body="&lt;p&gt;I know that DC power is essential for avionics and that in medium and big airplanes AC (28 V, 400 Hz) is used with DC (28 V). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small airplanes have a starter-generator that provides DC, but do they have an inverter too, to provide AC? If yes, then why use AC, and in which systems? And when is AC 26 V used? &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="1467" LastEditDate="2016-03-31T13:45:37.913" LastActivityDate="2016-04-30T09:32:08.150" Title="Do small airplanes have AC power?" Tags="&lt;electrical-system&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16234" PostTypeId="2" ParentId="9525" CreationDate="2015-06-24T13:01:39.050" Score="23" Body="&lt;p&gt;Another reason for the siren is that during the first years of WWII most army's ground transportation was horse drawn. You freak the horses and the unit does not move.  The French, Polish, and Russian armies used primarily horse drawn transport. The British and American armies used trucks.  A truck can't freak out like a horse.&lt;/p&gt;&#xA;" OwnerUserId="9041" LastEditorUserId="5517" LastEditDate="2016-04-29T12:30:25.253" LastActivityDate="2016-04-29T12:30:25.253" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16236" PostTypeId="1" AcceptedAnswerId="16238" CreationDate="2015-06-24T13:51:51.547" Score="2" ViewCount="587" Body="&lt;p&gt;Does the FAA have some specific air ambulance safety guidelines to adhere to?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="7532" LastEditDate="2015-06-24T15:09:06.070" LastActivityDate="2018-07-18T17:42:31.620" Title="Does the FAA have specific Air Ambulance safety guidelines?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16237" PostTypeId="2" ParentId="16220" CreationDate="2015-06-24T13:56:02.240" Score="4" Body="&lt;p&gt;Flow conditions are not so different, only the reaction of the flow to an obstacle is. By &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;shaping the intake appropriately&lt;/a&gt;, supersonic flow is handled easily, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/13096/what-are-the-merits-of-an-inlet-cone-spike-centerbody-vs-a-2d-inlet/13109#13109&quot;&gt;shocks will be helpful&lt;/a&gt; in decelerating and compressing the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, supersonic flow demands sharp intake lips which are hit by the flow at the right angle, otherwise drag rises quickly to intolerable levels. These sharp lips will cause flow separation in subsonic flow when hit by the flow at an angle, so aerodynamic tricks like &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;bypass doors&lt;/a&gt; need to be added to the intake to keep flow angles at the intake lips in check.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the intake will ensure a &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;flow speed around Mach 0.5&lt;/a&gt; at the compressor face of the engine, regardless of flight speed. Therefore, the engine will not need to be optimized for supersonic flight. However, to keep its frontal area low and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use/9666#9666&quot;&gt;nozzle speed high&lt;/a&gt;, its &lt;a href=&quot;https://aviation.stackexchange.com/questions/14509/in-what-way-are-the-concordes-engines-considered-efficient&quot;&gt;bypass ratio&lt;/a&gt; should be low. The only troubles this causes are increased engine fuel consumption and &lt;a href=&quot;https://aviation.stackexchange.com/questions/11884/do-nacelles-around-aircraft-engines-help-in-reducing-the-engine-sound/11891#11891&quot;&gt;noise&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-06-24T20:02:26.393" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16238" PostTypeId="2" ParentId="16236" CreationDate="2015-06-24T14:12:57.033" Score="3" Body="&lt;p&gt;Check out &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_135-14B.pdf&quot;&gt;this document&lt;/a&gt; published by the FAA which seems to be recent and some notes &lt;a href=&quot;http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=15794&quot;&gt;here&lt;/a&gt; on the same topics. The full rules can be found in the FAR at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=0a482d6d7bc8578f93413121610c70d8&amp;amp;mc=true&amp;amp;node=pt14.3.135&amp;amp;rgn=div5#sp14.3.135.l&quot;&gt;Part 135 Subpart L—Helicopter Air Ambulance Equipment, Operations, and Training Requirements&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are required to do a preflight risk analysis as per §135.617 but this is not really any different than what anyone should be doing before any flight however for them it is very specifically outlined. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Each certificate holder conducting helicopter air ambulance operations must establish, and document in its operations manual, an&#xA;  FAA-approved preflight risk analysis that includes at least the&#xA;  following—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Flight considerations, to include obstacles and terrain along the&#xA;  planned route of flight, landing zone conditions, and fuel&#xA;  requirements;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Human factors, such as crew fatigue, life events, and other&#xA;  stressors;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Weather, including departure, en route, destination, and&#xA;  forecasted;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) A procedure for determining whether another helicopter air&#xA;  ambulance operator has refused or rejected a flight request; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Strategies and procedures for mitigating identified risks,&#xA;  including procedures for obtaining and documenting approval of the&#xA;  certificate holder's management personnel to release a flight when a&#xA;  risk exceeds a level predetermined by the certificate holder.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Each certificate holder must develop a preflight risk analysis&#xA;  worksheet to include, at a minimum, the items in paragraph (a) of this&#xA;  section.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Prior to the first leg of each helicopter air ambulance operation,&#xA;  the pilot in command must conduct a preflight risk analysis and&#xA;  complete the preflight risk analysis worksheet in accordance with the&#xA;  certificate holder's FAA-approved procedures. The pilot in command&#xA;  must sign the preflight risk analysis worksheet and specify the date&#xA;  and time it was completed.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) The certificate holder must retain the original or a copy of each&#xA;  completed preflight risk analysis worksheet at a location specified in&#xA;  its operations manual for at least 90 days from the date of the&#xA;  operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-24T14:12:57.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16239" PostTypeId="2" ParentId="16225" CreationDate="2015-06-24T14:35:28.873" Score="3" Body="&lt;p&gt;Strictly for the DC-9/MD-80 series there are two methods available.&lt;/p&gt;&#xA;&lt;p&gt;One is the engine sync system which synchronizes one engine to the other to prevent the droning sound when the engines aren't running at quite the same setting. There are two modes N1 and N2. The system compares the speeds of the two engines and adjust the left engine to match the right engine. When the system switch is turned OFF, the system continues to SYNC the engines using EPR.&lt;/p&gt;&#xA;&lt;p&gt;The other is an active noise reduction system which adds new engine mounts designed to reduce the noise.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flightglobal.com/news/articles/lord-nvx-system-quietens-dc-9md-80-cabin-1554/&quot; rel=&quot;noreferrer&quot;&gt;http://www.flightglobal.com/news/articles/lord-nvx-system-quietens-dc-9md-80-cabin-1554/&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;LORD HAS RECEIVED US certification for its NVX active noise-and-vibration control system on the McDonnell Douglas DC-9 and MD-80. The company says that its system is the first to be approved for use on large commercial aircraft, and &amp;quot;...is being considered for several DC-9/MD-80 installation programmes.&amp;quot; Approval follows installation of the NVX on a corporate MD-87.&lt;/p&gt;&#xA;&lt;p&gt;The system consists of actuators on the engine-mounting yoke which counteract engine vibration and so reduce cabin noise. The actuators are driven continuously by a controller based on cabin-noise data from microphones installed behind the trim or under the floor.&lt;/p&gt;&#xA;&lt;p&gt;The results are most noticeable in the aft cabin, where engine tones typically measure 20dB above background noise, says Lord, adding: &amp;quot;The NVX Active System eliminates these tones on the ground, as well as during take-off, cruise and descent.&amp;quot; Programme manager Becky Weih says that noise levels are so reduced that the rear of the cabin &amp;quot;...is no louder than the front&amp;quot;. Erie, Pennsylvania-based Lord says the NVX has been approved on several corporate-aircraft types.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-24T14:35:28.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16240" PostTypeId="2" ParentId="16231" CreationDate="2015-06-24T16:20:01.353" Score="10" Body="&lt;p&gt;It is a Wright, allright, but more probably an EX. The EX was a modified Model R, which in turn was a modification of the Model B. The R and the EX were single seaters, whereas the B would seat two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of a Model B replica, as taken from its &lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_Model_B&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt; article:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/aawW3.jpg&quot; alt=&quot;Picture of a Model B replica&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of a Model EX, taken from &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Model_EX.htm&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; site.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2eD01.jpg&quot; alt=&quot;Picture of the &amp;quot;Vin Fizz&amp;quot;, a Wright Model EX&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EX was the model used by &lt;a href=&quot;https://en.wikipedia.org/wiki/Calbraith_Perry_Rodgers&quot; rel=&quot;noreferrer&quot;&gt;Cal Rodgers&lt;/a&gt; for his epic transcontinental flight. Note the lengthened tail and the closer wings, which allowed to reduce rigging wire and, thus, drag. The &quot;72&quot; shows the same features, so I think it is a Wright Model EX.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-24T16:25:17.283" LastActivityDate="2015-06-24T16:25:17.283" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16242" PostTypeId="1" CreationDate="2015-06-24T16:51:18.203" Score="4" ViewCount="888" Body="&lt;p&gt;If a small scale UAV (wingspan &amp;lt;2 metres) was to be fitted with solar panels on its wings to have more power available, would the addition of these panels cause an increase in the drag coefficient, and consequently aircraft drag? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though wind tunnel testing would be required to ascertain the exact change in drag, can one theoretically anticipate a change in drag on account of these solar panels? Furthermore, will the minimal variation in surface thickness on account of the panels result in the same?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solar panel thickness is of the order of micrometres. &lt;/p&gt;&#xA;" OwnerUserId="189" LastEditorUserId="572" LastEditDate="2015-06-25T11:21:56.620" LastActivityDate="2015-06-25T22:30:49.657" Title="Would solar panels on the wing of an aircraft increase drag?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;unmanned-aerial-vehicle&gt;&lt;fixed-wing&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16243" PostTypeId="2" ParentId="16005" CreationDate="2015-06-24T17:14:59.513" Score="6" Body="&lt;p&gt;Many older aircraft could be equipped with an optional external air driven generator, including, for example, the Luscombe 8A. Some air driven generator models were granted a Supplemental Type Certificate (STC) allowing them to be added to specific aircraft, such as the venerable J-3 Cub. The reason these were used is that, as you surmise, the engine is not equipped with any mechanism to drive an alternator or generator, i.e., there is no pulley, no gear mechanism, etc. Examples of those engines, still in use today, are the A-65, A-75 and original C-85. Newer designs of air driven generators are still available today, such as the BPE14 TURBO STAND-BY ALTERNATOR. The disadvantages include increased drag and exposure to ground obstacles, debris and of course, birds and bugs!&lt;/p&gt;&#xA;" OwnerUserId="9043" LastActivityDate="2015-06-24T17:14:59.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16244" PostTypeId="1" CreationDate="2015-06-24T17:16:31.513" Score="5" ViewCount="1696" Body="&lt;p&gt;Most commercial airliners are rated to take +2.5g and -1.0g.  Why is this?  Is it designed that way on purpose?  To clarify, this would mean that the cost difference between -1g and -2.5 g is minuscule, so price (and thus engineering difficulty, which drives price) isn't really a factor.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, are there in fact significant difficulties with creating a frame that can handle a lot of negative Gs?  (And if there are, what are they?)&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-06-24T17:38:30.810" Title="Why can planes generally take more positive g's than negative g's?" Tags="&lt;aircraft-design&gt;&lt;airframe&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-06-24T19:57:18.333" ContentLicense="CC BY-SA 3.0" />
  <row Id="16245" PostTypeId="2" ParentId="16244" CreationDate="2015-06-24T17:38:30.810" Score="7" Body="&lt;p&gt;It's partly pragmatic (you start from +1.0 G, so why not optimize for that???) and partly because (most) aircraft are designed to carry human beings.  Humans as well as a lot of other things are FAR more tolerant of positive G-forces than they are negative G-forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's very little technical reason that you couldn't design an aircraft wing and other structures to handle high negative G loads.  But adding that strength also means adding weight, complexity, and cost.  And since the benefit of being able to pull high negative G loads is pretty small, very few designers choose to do this.&lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-06-24T17:38:30.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16246" PostTypeId="2" ParentId="16193" CreationDate="2015-06-24T17:47:38.447" Score="5" Body="&lt;p&gt;Here is a link to John S. Denker's web book on airfoils. This is probably the definitive explanation of how wings work.  John Denker has a bunch of websites worth checking out.&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.av8n.com/how/htm/airfoils.html&quot;&gt;http://www.av8n.com/how/htm/airfoils.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line: for a 150,000 lb. aircraft to stay in the air, it must impart 150,000 lbft of momentum to the air through which it passes. You can talk about air pressure differences (etc.) but that's only the beginning of the explanation.  If you think equal transit time, or wing curvature is what makes wings work, this is a must-read.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastActivityDate="2015-06-24T17:47:38.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16247" PostTypeId="1" AcceptedAnswerId="16255" CreationDate="2015-06-24T20:15:06.127" Score="28" ViewCount="6387" Body="&lt;p&gt;Do jet contrails impact weather at the ground? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="595" LastEditDate="2016-06-07T09:09:41.513" LastActivityDate="2017-09-17T07:57:35.363" Title="Do jet contrails impact weather?" Tags="&lt;weather&gt;&lt;contrails&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16248" PostTypeId="2" ParentId="16247" CreationDate="2015-06-24T20:15:06.127" Score="14" Body="&lt;p&gt;Penn State researchers, led by Andrew M. Carleton, professor of geography, found that jet contrails can affect ground temperatures. (&lt;a href=&quot;http://news.psu.edu/story/361041/2015/06/18/research/jet-contrails-affect-surface-temperatures&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Bernhardt and Carleton looked at temperature observations made at&#xA;  weather station sites in two areas of the U.S., one in the South in&#xA;  January and the other in the Midwest in April. They paired daily&#xA;  temperature data at each contrail site with a non-contrail site that&#xA;  broadly matched in land use-land cover, soil moisture and air mass&#xA;  conditions. The contrail data, derived from satellite imagery, were of&#xA;  persisting contrail outbreaks. The researchers reported their results&#xA;  in a recent issue of the International Journal of Climatology.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;They found that contrails depress the difference between daytime and&#xA;  nighttime temperatures, typically decreasing the maximum temperature&#xA;  and raising the minimum temperature. In this respect, the contrail&#xA;  clouds mimic the effect of ordinary clouds.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The researchers report that the &quot;diurnal temperature range was&#xA;  statistically significantly reduced at outbreak stations versus&#xA;  non-outbreak stations.&quot; In the South, this amounted to about a 6&#xA;  degree Fahrenheit reduction in daily temperature range, while in the&#xA;  Midwest, there was about a 5 degree Fahrenheit reduction. Temperatures&#xA;  the days before and after the outbreaks did not show this effect,&#xA;  indicating that the lower temperatures were due to the contrail&#xA;  outbreaks.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Weather forecasting of daytime highs and lows do not include&#xA;  contrails,&quot; said Carleton. &quot;If they were included in areas of contrail&#xA;  outbreaks, they would improve the temperature forecasts.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The National Science Foundation supported this work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=7O8FGUtLNfU&amp;amp;feature=youtu.be&quot;&gt;https://www.youtube.com/watch?v=7O8FGUtLNfU&amp;amp;feature=youtu.be&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-06-24T20:15:06.127" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16249" PostTypeId="1" AcceptedAnswerId="16251" CreationDate="2015-06-24T20:28:57.947" Score="20" ViewCount="19258" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/9602/how-do-pilots-foresee-turbulence&quot;&gt;this question&lt;/a&gt; about turbulence and how pilots foresee it, and in one of the answers, @Rhino Driver states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Weather Radar&lt;/strong&gt; Just like using your eyes, except the radar can see further through haze and other clouds. Typically this is useful for finding embedded thunderstorms, but it can also be useful to find areas of potential turbulence&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BnAVK.jpg&quot; alt=&quot;Weather Radar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that make me wonder...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does the airliner's on-board weather radar work?&lt;/li&gt;&#xA;&lt;li&gt;Is it connected to ground base stations to synchronize the weather info?&lt;/li&gt;&#xA;&lt;li&gt;What kind of &quot;weather types&quot; can it detect? (i.e. thunderstorms, light rain, clear weather) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="22550" LastEditDate="2018-12-23T03:45:47.740" LastActivityDate="2018-12-23T03:45:47.740" Title="How does the weather radar work?" Tags="&lt;airliner&gt;&lt;flight-instruments&gt;&lt;radar&gt;&lt;weather-radar&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16250" PostTypeId="2" ParentId="16249" CreationDate="2015-06-24T20:41:18.633" Score="13" Body="&lt;p&gt;They are not connected to the ground, they are RADARs and operate independently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RADAR sends pulses, typically in the 10cm or 5cm range, which are reflected by water droplets.  The greater the concentration of droplets, the more the reflection (more power returned to the RADAR) which is used to provide the colours. Green means light density, orange means medium and red high.  Not shown is magenta (or purple) which is the &lt;strong&gt;really&lt;/strong&gt; nasty stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some weather RADARs also use the &lt;a href=&quot;https://en.wikipedia.org/wiki/Doppler_effect&quot;&gt;Doppler&lt;/a&gt; effect to show relative wind speed and turbulence in these areas.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clear air is where there is no colour between you and the first return (first bit of colour).  As DeltaLima correctly states below, it is possible for the signal to be attenuated so much that there is nothing to paint so no colour beyond the first return cannot be interpreted as clear air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can detect rain, thunderstorms etc and some models, turbulence.  You can also change the &quot;gain&quot; of the receiver to produce different displays to better see the bad stuff and can often be tilted up and down to see what's above or below and to get some sense of how high a storm is.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-06-24T21:47:26.940" LastActivityDate="2015-06-24T21:47:26.940" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16251" PostTypeId="2" ParentId="16249" CreationDate="2015-06-24T20:42:31.963" Score="24" Body="&lt;p&gt;It works the same way any radar works.  An antenna broadcasts a pulse of energy and listens for its reflection and interprets the power of the reflection to calculate the reflectivity factor Z, expressed in decibels dBZ (helpful because return power varies across many orders of magnitude).  Weather radar can see water, hail, bugs, birds, bats and bigger things, and the ground but not clouds.  Higher return power can mean more objects or bigger objects.  A basic single-polarization radar cannot tell the difference between a tons of small rain drops and a fewer big raindrops.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The particulars of the radar on any aircraft are generally going to be determined by the antenna size, as the optimal frequency of emission varies for a given antenna.  The large S-band* dishes that make up the ground based WSR-88D network are quite big (around 10m).  S-band is a good choice because they have low attenuation and can penetrate through storms and see things behind them.  Airplanes can't use S-band though, because the antennas are too big to put on the airplane and require too much power to fully utilize them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane radars are generally in the X-band*.  X-band can see smaller particles than S-band but attenuates easier.  This means if a big storm is in front of you, the energy doesn't penetrate far into the storm and may not show you the whole storm.  These are great short range radars and work well in airborne applications as long as you are aware of the issue with attenuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplane radar displays typically only display information from the on-board radar and do not downlink any additional information from ground stations.  Onboard radar are usually adjustable in the vertical by the pilots, so they can point the radar up or down as needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example of a radar antenna and associated electronics on a Cessna Citation 501:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YlLz8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;sub&gt;Image by Dtom, Wikimedia Commons.   &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Cessna501_radar.JPG&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/File:Cessna501_radar.JPG&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*S-band is 8-15 cm / 2-4 GHz&lt;br&gt;&#xA; X-band is 2.5-4 cm / 8-12 GHz&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-06-24T21:05:03.077" LastActivityDate="2015-06-24T21:05:03.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16252" PostTypeId="2" ParentId="16247" CreationDate="2015-06-24T20:43:35.983" Score="3" Body="&lt;p&gt;They can very slightly affect surface temperatures, just as a similar amount of normal cloud cover would. However, this effect is slight and is not weather modification in the sense that conspiracy theorists claim regarding supposed 'chemtrails.' And, certainly, there is nothing clandestine about contrails. No one attempts to hide them (or, if they are, they're doing a very bad job of it, since it's public knowledge and they're quite easy to see.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to answer your questions, yes, they can have very slight affects on the weather (specifically, surface temperature, usually near major airports or air traffic routes,) but, no they have nothing whatsoever to do with any sort of government conspiracy.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-06-24T20:43:35.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16253" PostTypeId="2" ParentId="16247" CreationDate="2015-06-24T21:04:25.000" Score="17" Body="&lt;p&gt;In the days immediately following the Twin Towers 911 attacks when there was no air traffic, a study found that the difference between night and day temperatures was greater and that day time temperatures were around a degree higher. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea about conspiracies to modify weather and chemtrails is well and truly shown to be complete nonsense - just Google for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.csmonitor.com/Environment/Bright-Green/2010/0201/Airplane-contrails-and-their-effect-on-temperatures&quot;&gt;Post 911 study&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-06-24T21:04:25.000" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16255" PostTypeId="2" ParentId="16247" CreationDate="2015-06-24T22:27:43.337" Score="24" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on past observations and a study led by Patrick Minnis from NASA, contrails could result in increasing the temperature over the ground by 1°C every 30 years over the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a study by German researchers Ulrike Burkhardt and Bernd Kärcher, the effect of contrails is comparable in other areas with a similar level of air traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the air traffic is said to be &lt;a href=&quot;http://www.iata.org/pressroom/pr/pages/2013-12-10-01.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;about to increase very quickly&lt;/a&gt;, the effects of contrails on the temperature may increase too.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Contrails and natural cirrus: So similar that studies are difficult&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrails are like cirrus, and actually some just become persistent cirrus. Sometime it's difficult to tell which one is a condensation trail, which one is a natural cloud. This makes more difficult the study of contrails effects, and introduces many uncertainties that need to be reduced:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IACz7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://loe.org/shows/segments.html?programID=02-P13-00022&amp;amp;segmentID=2&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current studies take into account only the young contrail-cirrus, because they are still relatively easy to differentiate from natural cirrus, due to their linear shape. Most aged contrail-cirrus are not differentiable and are not counted as aircraft generated. This means the current results potentially under-estimate the effects of contrails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pertaining to the discussion, contrail-cirrus as clouds:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Induce a &lt;a href=&quot;https://en.wikipedia.org/wiki/Cloud_feedback&quot; rel=&quot;nofollow noreferrer&quot;&gt;cloud-feedback&lt;/a&gt;, i.e. the coupling between cloudiness and surface air temperature.&lt;/li&gt;&#xA;&lt;li&gt;Induce a &lt;a href=&quot;https://en.wikipedia.org/wiki/Radiative_forcing&quot; rel=&quot;nofollow noreferrer&quot;&gt;radiative forcing&lt;/a&gt;, they increase the portion of the energy not re-emitted to space. The quantity is expressed in mW/m².&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Increasing the air temperature has a link with increasing ground or oceans temperature, but the two notions mustn't be mixed. However cirrus are suspected to play a role in the global warming, because they could introduce a &lt;a href=&quot;https://en.wikipedia.org/wiki/Cirrus_cloud#Effects_on_climate&quot; rel=&quot;nofollow noreferrer&quot;&gt;positive feedback&lt;/a&gt; into this warming.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Study: Coverage and effects of contrail-cirrus&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nature.com/nclimate/journal/v1/n1/full/nclimate1068.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Global radiative forcing from contrail cirrus&lt;/a&gt; published in Nature in 2011 was a study to evaluate the contrail-cirrus coverage, and its impact. Conclusion:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aviation makes a significant contribution to anthropogenic climate&#xA;  forcing. The impacts arise from [...] and from changes in cloudiness in the&#xA;  upper troposphere. An important but poorly understood component of&#xA;  this forcing is caused by ‘contrail cirrus’—a type of cloud that&#xA;  consist of young line-shaped contrails and the older irregularly&#xA;  shaped contrails that arise from them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The estimated effect is depicted on this map (mW/m²) from the study:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/E58Qg.png&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Net effect of contrails (CIC) warming compared to other aviation factors of warming:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AFDAv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://spie.org/x57653.xml&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Study: Effect of contrail-cirrus on US climate&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA conducted a study in 2004: Patrick Minnis, J. Kirk Ayers, Rabindra Palikonda, and Dung Phan -- &lt;a href=&quot;http://journals.ametsoc.org/doi/full/10.1175/1520-0442%282004%29017%3C1671%3ACCTAC%3E2.0.CO%3B2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Contrails, Cirrus Trends, and Climate&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This study was analyzed in Science Daily: &lt;a href=&quot;http://www.sciencedaily.com/releases/2004/04/040428061056.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Clouds caused by aircraft exhaust may warm the US climate&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Using published results from NASA's Goddard Institute for Space&#xA;  Studies (New York) general circulation model, Minnis and his&#xA;  colleagues estimated contrails and their resulting cirrus clouds would&#xA;  increase surface and lower atmospheric temperatures by &lt;strong&gt;0.36 to 0.54 degrees Fahrenheit per decade&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aviation radiative forcing in 2000: An update on IPCC (1999)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This study was included in a new one by R. Sausen et al. in 2005. It shown the radiative forcing by aircraft could have been slightly underestimated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NV0Nm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NV0Nm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://folk.uio.no/gunnarmy/paper/sausen_mz05.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;: Aviation radiative forcing in 2000: An update on IPCC (1999) - R. Sausen&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The US surface temperature is increasing by &lt;strong&gt;1°C every 30 years&lt;/strong&gt;: I would say this is &lt;em&gt;very&lt;/em&gt; significant for plants, life, water cycle, oceanic currents, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also look at @Simon good answer about the increase of the difference between night and day temperatures, by more than 1°C, during the 3 days civil air traffic was forbidden on September 2001. This increase seems to confirm contrail-cirrus limit cooling on night time.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-02-19T12:00:00.413" LastActivityDate="2017-02-19T12:00:00.413" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16256" PostTypeId="1" CreationDate="2015-06-24T23:49:34.890" Score="2" ViewCount="4033" Body="&lt;p&gt;Are the Total Hours and Total Cycles of an aircraft based on the Flight hours or Operational hours of an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="9050" LastEditorUserId="19" LastEditDate="2017-01-25T07:30:03.243" LastActivityDate="2017-01-25T07:30:03.243" Title="Are the total hours of an aircraft based on flight hours or operational hours?" Tags="&lt;aircraft-operations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16257" PostTypeId="1" AcceptedAnswerId="16271" CreationDate="2015-06-25T00:50:06.027" Score="10" ViewCount="1655" Body="&lt;p&gt;Can anyone help me to identify this WW1 aircraft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks as though it reads Otto No. 202 on the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sDGSe.jpg&quot; alt=&quot;WWonebiplane&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9040" LastEditorUserId="19" LastEditDate="2016-07-04T11:28:17.007" LastActivityDate="2016-07-04T11:28:17.007" Title="Can you help me identifying this WW1 German or Austrian airplane from my photo collection?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16258" PostTypeId="1" CreationDate="2015-06-25T00:55:45.773" Score="6" ViewCount="1464" Body="&lt;p&gt;Please help me identify this world war 1 fighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LEn2o.jpg&quot; alt=&quot;wwonefighter&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9040" LastEditorUserId="19" LastEditDate="2016-07-04T11:26:16.710" LastActivityDate="2016-07-04T11:26:16.710" Title="Could you help to identify this WW1 fighter?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16259" PostTypeId="1" CreationDate="2015-06-25T02:13:01.743" Score="3" ViewCount="1966" Body="&lt;p&gt;I have a T206H and The POH says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Current indication (AMPS) for both the main and standby batteries is&#xA;  provided at the bottom of the EIS bar (along the left margin of the&#xA;  MFD or PFD), labeled M BATT S. Main battery current is numerically&#xA;  displayed below the M. Main battery current greater than -1.5 amps is&#xA;  shown in white. Standby battery current is displayed numerically below&#xA;  the S. A positive current value (shown in white) indicates that the&#xA;  battery is charging. A negative current value (shown in amber)&#xA;  indicates that the battery is discharging. In the event the alternator&#xA;  is not functioning or the electrical load exceeds the output of the&#xA;  alternator, the main battery ammeter indicates the main battery&#xA;  discharge rate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The part that confuses me is the one that says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Main battery current greater than -1.5 amps is shown in white.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does that means that when the number is negative but greater than -1.5 it is OK, because it is in white?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And after 40 minutes of flight in normal daytime operations I have a -1.0 in the M BATT amps but the M BUS volts remain 28.3. What does this mean?&lt;/p&gt;&#xA;" OwnerUserId="9032" LastEditorUserId="62" LastEditDate="2017-01-24T15:34:35.130" LastActivityDate="2017-01-24T15:34:35.130" Title="How to interpret the electrical information on a G1000 T206H?" Tags="&lt;electrical-system&gt;&lt;g1000&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16261" PostTypeId="2" ParentId="16259" CreationDate="2015-06-25T04:22:14.467" Score="3" Body="&lt;p&gt;You've actually answered your own question back there:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A negative current value (shown in amber) indicates that the battery is discharging. In the event the alternator is not functioning or the electrical load exceeds the output of the alternator, the main battery ammeter indicates the main battery discharge rate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The 28.3 Volts reading is the electric energy charge supplied by the aircraft alternator (60-Amp alternator is standard and a 95-amp one is optional) through the main bus, whereas the M amp reading is what's happening to the main battery. In the situation you've described, you've got so many electrically-powered systems running, that the alternator, though operating normally, is unable to supply them all, so additional power is drawn from the battery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 206 PIM states that the Main battery Ammeter is color-coded white for values greater than -1.5 Amps, meaning that Cessna is not concerned with battery drains of 1.5 Amps or less (i.e. readings between -1.5 and 0). If the discharge rate is greater than 1.5 Amps (reading lower than -1.5), then the reading will be color-coded yellow. See below for an example of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TrlCO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-06-25T04:22:14.467" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16262" PostTypeId="1" AcceptedAnswerId="16265" CreationDate="2015-06-25T05:31:53.687" Score="13" ViewCount="3510" Body="&lt;p&gt;Is there any present technology where a large plane can carry a small plane (or multiple small planes) and drop it midair where the small plane deploys itself? This would be very good from defense point of view, where small fighter jets with limited range could be dropped off by large airplanes with very long range.&lt;/p&gt;&#xA;" OwnerUserId="8814" LastEditorUserId="3386" LastEditDate="2018-04-22T04:33:55.137" LastActivityDate="2018-04-23T12:06:32.000" Title="Can small airplanes be towed (or carried) as cargo to be dropped at some other location by air?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="7" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16264" PostTypeId="2" ParentId="16257" CreationDate="2015-06-25T05:55:32.480" Score="6" Body="&lt;p&gt;This is a world war 1 plane &lt;strong&gt;Otto Pusher&lt;/strong&gt; which was operated by the Germans. Here is another image : &lt;img src=&quot;https://i.stack.imgur.com/u6rCl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8814" LastActivityDate="2015-06-25T05:55:32.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16265" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T06:15:32.107" Score="17" Body="&lt;p&gt;If you are talking about externally carrying/deploying other aircraft, this has already been done with the B-52 (albeit for testing purposes) carrying the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot;&gt;X-15&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not too sure about having an aircraft drop out of a cargo bay such as the C-130.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note &lt;a href=&quot;https://en.wikipedia.org/wiki/Military_glider&quot;&gt;military gliders&lt;/a&gt; were used extensively during WW2 and some were capable of carrying light tanks. The gliders were usually towed behind larger bombers to give them the required altitude and speed. They were used because of their wooden construction allowing a stealthy approach due to the reduced radar signature.&lt;/p&gt;&#xA;" OwnerUserId="9053" LastEditorUserId="9054" LastEditDate="2015-06-25T06:52:39.903" LastActivityDate="2015-06-25T06:52:39.903" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16266" PostTypeId="1" AcceptedAnswerId="21728" CreationDate="2015-06-25T06:22:48.200" Score="4" ViewCount="314" Body="&lt;p&gt;Do Terrain awareness and warning system (TAWS) have blind spots when the helicopter is in unknown territory with unpredicted terrain or the TAWS systems coming nowadays have each and every terrain on earth?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="19" LastEditDate="2016-07-05T11:07:06.763" LastActivityDate="2016-07-05T11:07:06.763" Title="Do modern Terrain awareness and warning system (TAWS) have blind spots?" Tags="&lt;taws&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16267" PostTypeId="1" AcceptedAnswerId="16286" CreationDate="2015-06-25T06:41:50.780" Score="1" ViewCount="1447" Body="&lt;p&gt;What are the additional capabilities that 3D thrust vectoring (TVC) provides over 2D thrust vectoring? &lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="19" LastEditDate="2015-06-25T13:51:14.723" LastActivityDate="2015-06-26T23:28:36.863" Title="Does 3D Thrust vectoring (TVC) provide improved maneuverability over 2D TVC?" Tags="&lt;thrust-vectoring&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16268" PostTypeId="1" CreationDate="2015-06-25T06:55:24.153" Score="5" ViewCount="8069" Body="&lt;ul&gt;&#xA;&lt;li&gt;How do we define 2D and 3D thrust vectoring?&lt;/li&gt;&#xA;&lt;li&gt;What are the differences between the two?&lt;/li&gt;&#xA;&lt;li&gt;Is there anything called 1 D thrust vectoring?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerDisplayName="user8824" LastEditorUserId="65" LastEditDate="2015-06-25T14:09:42.377" LastActivityDate="2015-09-21T16:48:22.580" Title="What is 2D and 3D thrust vectoring?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;engine&gt;&lt;thrust-vectoring&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16269" PostTypeId="2" ParentId="16258" CreationDate="2015-06-25T06:55:57.893" Score="8" Body="&lt;p&gt;First of all, this is not a fighter, but a &lt;a href=&quot;https://en.wikipedia.org/wiki/Idflieg_aircraft_designation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-type airplane&lt;/a&gt;. A C-type was a two-seater and was mostly used for reconnaissance or ground attack. That it is a German plane is obvious, but the picture leaves out the details like propeller, wings and fin shape which would help in identifying it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noticeable is the six cylinder in-line engine, the triangular fin and the boxy fuselage. Of particular interest is the position of the horizontal tail which starts well ahead of the vertical. This restricts the &lt;a href=&quot;http://www.wwiaviation.com/German_2seaters.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;selection&lt;/a&gt; to these types:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Albatros C.III&lt;/li&gt;&#xA;&lt;li&gt;AEG C.IV (but the tail details don't match well)&lt;/li&gt;&#xA;&lt;li&gt;DFW C.V&lt;/li&gt;&#xA;&lt;li&gt;Rumpler C.I&lt;/li&gt;&#xA;&lt;li&gt;Rumpler C.IV to C.VII (they all looked very much alike)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From the limited information available, my best guess is the Rumpler C.I. See below for a side view from &lt;a href=&quot;http://rumplerddci.blogspot.de&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; source:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/EfusI.jpg&quot; alt=&quot;side view of a drawing of the Rumpler C.I&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;Now that MSalters has posted his answer, I think that he is right. It looks indeed like an Albatros C.I. I did not include this one in my search. Silly me.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-25T16:49:28.177" LastActivityDate="2015-06-25T16:49:28.177" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16270" PostTypeId="2" ParentId="16268" CreationDate="2015-06-25T07:01:42.387" Score="7" Body="&lt;p&gt;As previously seen &lt;a href=&quot;https://aviation.stackexchange.com/a/15441/1467&quot;&gt;in a comment section&lt;/a&gt;, there are two main schools of thought:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The dimensionality indicates the actuation Degree of Freedom (1D has&#xA;1 DoF per exhaust vector, 2D has 2).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The dimensionality indicates the aircraft attitudes that can be affected (2 exhaust vectors with 1 DoF each can affect pitch and roll, hence this would be a 2D thrust vectoring, 2 exhausts with 2 DoFs can affect all 3 attitude angles, hence 3D)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Using the definitions of these two approaches, to make a couple of examples, the F22 thrust vectoring is 1D for the first group and 2D for the second, while the Su30 is 2D and 3D respectively.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-25T07:40:36.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16271" PostTypeId="2" ParentId="16257" CreationDate="2015-06-25T07:22:18.223" Score="7" Body="&lt;p&gt;@DalamaniSingh is correct, but the people who built and flew this plane never called it &quot;Otto pusher&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gustav_Otto&quot; rel=&quot;noreferrer&quot;&gt;Gustav Otto&lt;/a&gt; was one of the seven children of Nikolaus Otto, who designed the first practical internal combustion engine and after whom the &lt;a href=&quot;https://en.wikipedia.org/wiki/Nikolaus_Otto#The_Otto_cycle&quot; rel=&quot;noreferrer&quot;&gt;Otto cycle&lt;/a&gt; is named. He started an aircraft factory in 1909 near Munich and later relocated north to Oberschleissheim. The first product of this factory was simply called &quot;Otto Doppeldecker&quot; (Otto biplane). It was produced from 1912 to 1915, but was obsolete by the time WWI started. The plane was mostly used for training. The factory had to close in 1915 and the historic building now houses a collection of aircraft and &lt;a href=&quot;http://www.deutsches-museum.de/en/flugwerft/information/&quot; rel=&quot;noreferrer&quot;&gt;has become a museum&lt;/a&gt;. In the attached restoration workshop, a &lt;a href=&quot;http://www.der-werftverein.de/akotto/otto.html&quot; rel=&quot;noreferrer&quot;&gt;replica&lt;/a&gt; was built recently.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="19" LastEditDate="2015-06-25T07:33:25.020" LastActivityDate="2015-06-25T07:33:25.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16272" PostTypeId="2" ParentId="15637" CreationDate="2015-06-25T08:01:17.657" Score="10" Body="&lt;p&gt;The idea is to generate a vortex near the fuselage. In most cases we do not want any vortexes, as the unnecessary air movement always causes an increase in drag. In this case however, you need them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the air flow separates from this small triangle wing while at large angles of attack, it gains a rotary motion (if you look at the left wing standing in front of the aircraft it will rotate clock-wise). This vortex inducts further swirling movement across the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if you are familiar with fluid dynamics, you can imagine that this will decrease air pressure at the top of the wing (not much impact on the bottom side), which is what we want - higher lift is generated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is more important in this the case, is the boundary layer. If you provide it with energy, making it more turbulent, it will pay off with sticking to the wing surface even while flying at large angles of attack. Obviously the larger is the angle without stall, the higher lift can be generated. Therefore an airplane with wing extensions can perform sick maneuvers like cobra and other more useful in aerial combat. Of course it requires a huge amount of spare thrust, but you do not have to worry about that in military jets.&lt;/p&gt;&#xA;" OwnerUserId="8994" LastActivityDate="2015-06-25T08:01:17.657" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16273" PostTypeId="2" ParentId="16268" CreationDate="2015-06-25T09:19:07.210" Score="-1" Body="&lt;p&gt;From &lt;a href=&quot;http://aircraft.wikia.com/wiki/Thrust_vectoring&quot; rel=&quot;nofollow&quot;&gt;Aircraft Wiki&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A plane has got thrust vectoring when it is able to direct its engine&#xA;  thrust in another direction to give it better maneuverability. If the&#xA;  plane is able to direct the thrust only in one direction it has 2D&#xA;  thrust vectoring control. If it's able to direct the thrust in all&#xA;  directions, (pitch,yaw and roll) it has 3D thrust vectoring.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="65" LastEditDate="2015-06-25T14:11:34.850" LastActivityDate="2015-06-25T14:11:34.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16274" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T09:30:51.590" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;small fighter jets with limited range could be dropped off by large airplanes with very long range&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That sounds like a one-way mission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some Zeppelins and some &lt;a href=&quot;http://www.airships.net/us-navy-rigid-airships/uss-akron-macon&quot;&gt;US Navy airships&lt;/a&gt; did carry small aircraft that could be both launched and, importantly from the pilot's perspective, recovered in mid-air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in the modern world, the approach you describe is not used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If fighters are needed beyond normal operational range of their bases, air forces will either use in-flight refuelling or create a forward operating base nearer the mission target. Aircraft carriers are a popular solution to this requirement, if adequate time is available.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-25T09:49:01.210" LastActivityDate="2015-06-25T09:49:01.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16275" PostTypeId="2" ParentId="16258" CreationDate="2015-06-25T09:44:46.433" Score="9" Body="&lt;p&gt;Pretty sure it's an &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/0/0f/Albatros_C.I.jpg&quot; rel=&quot;noreferrer&quot;&gt;Albatros C.I&lt;/a&gt;. Look at the access hatch with the double gills directly behind it, the three metal covers on the engine, the horizontal and vertical black marks on them, the upper wing support ending right between the two metal covers, the front support for the undercarriage ending right before the second gill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ktLGs.jpg&quot; alt=&quot;Albatros C.I&quot;&gt;&#xA;Albatros C.I (Picture copied from the link above)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Albatros C.III has a different tail, but that's invisible in the picture above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is another picture, showing the plane from the other side. Note the flush radiator on the side of the fuselage. (image &lt;a href=&quot;http://www.militaryimages.net/photopost/world-war-1-aircraft/p13233-albatros-c-i.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Pjk3U.jpg&quot; alt=&quot;Albatros C.I of the first production batch&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1956" LastEditorUserId="1961" LastEditDate="2015-06-25T16:49:03.397" LastActivityDate="2015-06-25T16:49:03.397" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16276" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T10:23:59.747" Score="11" Body="&lt;p&gt;Parasite aircraft is a concept that has been considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the era of the zeppelins several countries experimented with launching fighter aircraft from airships, mainly as a way to get the fighter crafts to a relevant altitude while conserving fuel.  However none of these projects where realized before the end of WWI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During WWII soviet used Tupolev TB-3's to carry I-16 dive bombers, a culmination of experiments started during the 1930's. Some of Japan's kamikaze crafts where also launched as parasite aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an escort role Germany experimented with parasite craft solutions as a way to bypass the very short operational range of rocket powered fighters, but these experiments where ultimately judged unsuitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extreme range of US strategic bombers in late WWII and early cold war lead US to consider parasite fighters as an escort solution.  However these attempts where eventually scrapped in favour of aerial refueling, as this was considered a safer option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Parasite_aircraft&quot;&gt;https://en.wikipedia.org/wiki/Parasite_aircraft&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3853" LastEditorUserId="572" LastEditDate="2015-06-25T11:20:04.787" LastActivityDate="2015-06-25T11:20:04.787" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16277" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T10:31:25.840" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;This would be very good from defense point of view, where small fighter jets with limited range could be dropped off by large airplanes with very long range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Parasite_aircraft&quot;&gt;Parasite aircraft&lt;/a&gt; as a way of increasing the range of fighters has been tried repeatedly, with everything from &lt;a href=&quot;https://en.wikipedia.org/wiki/Curtiss_F9C_Sparrowhawk&quot;&gt;airships&lt;/a&gt; to &lt;a href=&quot;https://en.wikipedia.org/wiki/FICON_project&quot;&gt;heavy bombers&lt;/a&gt; as the mothership.  It turns out to be much harder than it sounds, and has generally been abandoned in favor of dedicated tankers and mid-air refueling.&lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2015-06-25T10:31:25.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16278" PostTypeId="2" ParentId="16247" CreationDate="2015-06-25T11:05:48.973" Score="5" Body="&lt;p&gt;Yes, contrails affect the weather. The vapour particles are nucleii for condensation of more water. In WW2 the huge bomber fleets leaving Britain caused rain. &#xA;The effect of clouds on global warming is still not understood. They reflect the Sun's rays, but they also insulate the ground.&lt;/p&gt;&#xA;" OwnerUserId="8967" LastActivityDate="2015-06-25T11:05:48.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16279" PostTypeId="2" ParentId="16267" CreationDate="2015-06-25T12:05:20.167" Score="1" Body="&lt;p&gt;An aircraft always needs &quot;3D manoeuverability&quot; (pitch, yaw, roll). Whether you use TVC to perform one, two or all three functions, exclusively, or in combination with aerodynamic control surfaces is a matter of design choices and optimization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The choice truly depends on what are the requirements of the aircraft in question. Note that TVC in itself is not necessarily &quot;better&quot; than conventional control surfaces on the wing and/or tailplanes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aerodynamic control surfaces are very efficient (with enough speed), but take some space and induce loads in the airframe. Ailerons on a wing take space that could be used for flaps. Tailplanes are a pure cost of weight and drag that you pay for maneuverability (and stability).&lt;/li&gt;&#xA;&lt;li&gt;TVC costs a lot of weight and complexity, but in turn has little to no direct penalty on drag. However, note that it has a rather limited efficiency (which is directly tied to the thrust of the aircraft -- which is not so good: ideally you want thrust and attitude control to be independent).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Maneuverability always has a cost. So the question really is: For a particular &lt;strong&gt;aircraft configuration&lt;/strong&gt;, and for a particular &lt;strong&gt;requirement of maneuverability&lt;/strong&gt; (in pitch, yaw, roll), and for a particular combination of &lt;strong&gt;optimization criteria&lt;/strong&gt; (minimize weight, drag, costs, complexity,...): What is the combination of aerodynamic surfaces and TVC (and other means) that meets the requirement while minimizing the criteria?&lt;/p&gt;&#xA;" OwnerUserId="9059" LastActivityDate="2015-06-25T12:05:20.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16280" PostTypeId="1" AcceptedAnswerId="16281" CreationDate="2015-06-25T12:06:07.623" Score="8" ViewCount="1293" Body="&lt;p&gt;Do pilots need special training to land Lockheed U-2 reconnaissance aircraft as its body is too shallow and is a wide wing aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-06-25T12:35:41.307" Title="Do pilots need special training to land Lockheed U-2 reconnaissance aircraft?" Tags="&lt;landing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16281" PostTypeId="2" ParentId="16280" CreationDate="2015-06-25T12:35:41.307" Score="20" Body="&lt;p&gt;All military pilots will receive special training when learning to fly a new aircraft, whether that is in a simulator, a 2 seater version of the same aircraft, or both. An F-16 pilot is not going to fly a F-15 without considerable training. Training is recommended even for light aircraft as well when learning a new model. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are asking whether the U2 is harder to land than many other airplanes then yes, the U2 is a very challenging aircraft to land because of it's shape, but also because the pilot can see very little of the runway. In fact the procedure for landing a U2 calls for a vehicle to speed down the runway behind it with another U2 pilot in it to talk the flying pilot down. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-06-25T12:35:41.307" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16282" PostTypeId="2" ParentId="16247" CreationDate="2015-06-25T12:37:03.937" Score="-1" Body="&lt;p&gt;Not in a real sense. yes they do put water vapor in the air. so does drying your clothes in the dryer. or taking a shower. or driving your car. while it makes a visible cloud the amount of water is much less than cars traveling the same distance due to the fuel efficiency of flight vs. driving.  &lt;/p&gt;&#xA;" OwnerUserId="8963" LastActivityDate="2015-06-25T12:37:03.937" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16283" PostTypeId="2" ParentId="16256" CreationDate="2015-06-25T13:15:43.707" Score="1" Body="&lt;p&gt;I'm not sure about the total hours but cycles is based on take offs and landings. As per &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_maintenance_checks&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the cycle count (takeoff and landing is considered an aircraft &quot;cycle&quot;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also go on to say &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;or the number of hours flown since the last check&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;so I'm guessing it's flight hours. For what it's worth in small GA planes this is generally measured with a Hobbs meter which clocks hours based on the engine running. That does not mean you have left the ground. So any hour based service on a GA plane is going to be done on that clock not a flight time clock (which none of the planes I fly even track). &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2015-12-30T09:54:57.873" LastActivityDate="2015-12-30T09:54:57.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16284" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T13:22:51.430" Score="5" Body="&lt;p&gt;Germany had some (very) limited success in WWII with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mistel&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mistel&lt;/a&gt; concept, which is basically the opposite of what you mentioned:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;smaller&lt;/strong&gt; of two craft was the piloted one, the &lt;strong&gt;bigger&lt;/strong&gt; craft being an explosive-carrying drone -- like a really big glide bomb. The most common combination was a Fw-190 figher/bomber carrying a Ju-88 drone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8jNz6.jpg&quot; alt=&quot;&amp;quot;Mistel-4s&amp;quot; by U.S. Army - anonymous-generaltopics.blogspot.com/2008/06/mistel.html. Licensed under Public Domain via Wikimedia Commons - commons.wikimedia.org/wiki/File:Mistel-4s.jpg#/media/File:Mistel-4s.jpg&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2401" LastEditorUserId="2401" LastEditDate="2015-06-26T05:47:12.737" LastActivityDate="2015-06-26T05:47:12.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16285" PostTypeId="2" ParentId="16256" CreationDate="2015-06-25T14:04:56.557" Score="4" Body="&lt;p&gt;&lt;strong&gt;Cycle&lt;/strong&gt;&lt;br&gt;&#xA;One takeoff and one landing makes up one cycle. Counting cycles is important to keep the number of times the cabin was pressurized (with the assumption that the airplane flies at high altitude). It is also significant for engine maintenance. A cycle and flight/operation time are not related.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Hours&lt;/strong&gt;&lt;br&gt;&#xA;This is the time when an airplane is in operation &lt;em&gt;(more on this below)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Time&lt;/strong&gt;&lt;br&gt;&#xA;Generally speaking, it is the time when an airplane is flying. It is the duration from when landing gears leave the ground to when they touch the ground again. Pilots are not paid by this. In my opinion, it is mostly used by flight trackers to inform people if an airplane has landed or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Operation Time&lt;/strong&gt;&lt;br&gt;&#xA;For GA airplanes, when the airplanes is started, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hobbs_meter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hobbs meter&lt;/a&gt; starts and it stops when the engine is turned off. Most commonly, this is how rental GA airplanes' rent is calculated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For commercial airplanes, &lt;a href=&quot;https://aviation.stackexchange.com/a/1821/65&quot;&gt;pilots pay clock&lt;/a&gt; starts when parking brake is released and ends when the parking brake is set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, total hours is more closely related to operation time.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you are talking about total time and total cycles in reference of retiring an airplane, that is a different discussion. Each part of an airplane has a certain life. Though most of the time it can be predicted, but sometimes a certain component fails earlier than the expected life and therefore needs to be replaced. Airplane manufactures do specify a design life limit, but that is normally changed because of regular maintenance.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-25T14:04:56.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16286" PostTypeId="2" ParentId="16267" CreationDate="2015-06-25T15:17:51.097" Score="6" Body="&lt;p&gt;Thrust vectoring allows to control an aircraft when the airflow over its control surfaces has separated. Before thrust vectoring, the range of angles of attack in which an aircraft could be controlled was rather restricted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the &lt;a href=&quot;http://fas.org/man/dod-101/sys/ac/x-31.htm&quot;&gt;X-31&lt;/a&gt;, it was for the first time possible to control a completely stalled aircraft, which enabled much quicker maneuvering in order to get the nose pointed at an adversary. This was powerfully demonstrated by &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/6.2004-5173&quot;&gt;mock air combats with an F-18&lt;/a&gt;. The X-31 used a rather simple arrangement with three paddles at the engine exhaust, and this allowed to create both pitch and yaw moments. This makes it what you call a 3D thrust vectoring aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern thrust vectoring nozzles are round and allow to deflect the thrust by up to 20° in both pitch and yaw, making them also what you call 3D. However, this geometry will scatter radar waves in all directions, which makes it unsuitable for stealth aircraft. Therefore, stealthy designs can use only two straight vanes above and below the jet exhaust, which will create only pitch moments. This is what you call 2D thrust vectoring. When two engines are installed, differential deflection will allow to create limited roll moments, but the powerful side forces which allowed the X-31 to rotate its nose (and radar) quickly into the path of its adversary will no longer be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stealthy thrust vectoring will still allow to control the aircraft at all angles of attack, but the yaw rates possible with a regular thrust vectoring nozzle are no longer achievable. This, and the structural mass of a rectangular exhaust, are the distinct disadvantages of stealthy nozzle designs.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-25T15:44:02.330" LastActivityDate="2015-06-25T15:44:02.330" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16287" PostTypeId="2" ParentId="16262" CreationDate="2015-06-25T15:22:49.443" Score="7" Body="&lt;p&gt;Since your question is about the tech, it very much does exist in a &lt;a href=&quot;http://www.acmp.com/blog/parasite-aircraft-aka-composite-aircraft.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;few forms&lt;/a&gt; at least for aircraft of varying size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_X-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bell X-1&lt;/a&gt; (the plane that broke the sound barrier) was a mid flight deploy from a B-29. This was a result of its low fuel load it could not really get its self off the ground and then have enough fuel to break the sound barrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0whG9.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This became common for a lot of the high speed test crafts developed over the years. Up through the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-15&lt;/a&gt; (the fastest thing out there) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jfenr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first space shuttle tests were done by &lt;a href=&quot;https://www.youtube.com/watch?v=dijD4J3vX5Y&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying the shuttle to altitude&lt;/a&gt; on a modified 747 and deploying it for an unpowered decent so the tech is there even for large craft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Av6HH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more modern &lt;a href=&quot;https://en.wikipedia.org/wiki/SpaceShipOne&quot; rel=&quot;nofollow noreferrer&quot;&gt;Space Ship One&lt;/a&gt; also uses this configuration to get it to altitude easier. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/vNfwG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tech is there and has been used over the years. Now to the more realistic question &quot;would you do it&quot; most likely no. As you mentioned there is a case for small limited range planes being deployed at distance but the simpler solution to that is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_refueling&quot; rel=&quot;nofollow noreferrer&quot;&gt;mid-air refuel&lt;/a&gt;. This accomplishes the range extension and allows the plane to get back home. The other option is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Drop_tank&quot; rel=&quot;nofollow noreferrer&quot;&gt;drop tank&lt;/a&gt; which also extends the range of a plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Another kinda of cool solution to the problem was to weld 2 planes into one like the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang&quot; rel=&quot;nofollow noreferrer&quot;&gt;North American F-82 Twin Mustang&lt;/a&gt;. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/A83Dm.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-25T20:18:08.517" LastActivityDate="2015-06-25T20:18:08.517" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16288" PostTypeId="2" ParentId="12956" CreationDate="2015-06-25T15:25:51.797" Score="3" Body="&lt;p&gt;Lets see if I can make it more simplified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft has:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Basic Empty Weight (BEW)&lt;/strong&gt; is the weight of the aircraft &quot;as built&quot; and includes the weight of the structure, power plant, furnishings, installations, systems and other equipment that are considered an integral part of an aircraft before additional operator items are added for operation.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Dry Operating Wieght (DOW)&lt;/strong&gt; BEW + Weight of Crew (Pilot + Cabin including their bags) + Pantry&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Operating Weight (OW)&lt;/strong&gt; DOW + Takeoff fuel (i.e. Ramp Fuel - Taxi fuel)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Maximum Zero Fuel Weight (MZFW)&lt;/strong&gt; DOW + Payload (anything put on the aircraft that generates revenue to the company, e.g. passenger, baggage, cargo, mail and fret)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Maximum Taxi Weight (MTW)&lt;/strong&gt; MZFW + Ramp fuel&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Maximum Takeoff Weight (MTOW)&lt;/strong&gt; MZFW + Takeoff fuel, or MTW - Taxi fuel&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Maximum Landing Weight (MLW)&lt;/strong&gt; MTOW - Trip Fuel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9063" LastEditorUserId="65" LastEditDate="2015-06-25T15:56:48.877" LastActivityDate="2015-06-25T15:56:48.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16289" PostTypeId="2" ParentId="16267" CreationDate="2015-06-25T15:35:37.780" Score="2" Body="&lt;p&gt;In short, yes; the ability to vector thrust to the sides of the aircraft, inducing yaw, does provide an advantage in maneuvering over pitch-only vectoring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the Su-30 &quot;SM&quot; and &quot;MK&quot; variants, which have 3D thrust vectoring. Here's a Su-30 at an airshow (I'm unsure of the exact variant) performing a range of post-stall aerobatics:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=ujenrmoeALE&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=ujenrmoeALE&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of these maneuvers require the pilot to be able to kick his rear end to one side or the other without the aid of aerodynamic control surfaces (such as the post-stall Immelmann, the J-turn, the Super Cobra which basically stands the jet on its tail in mid-air, etc) and thus could not be performed, at least not to the same degree, by an aircraft like the F-22. The utility of such maneuvers in aerial combat is unknown and probably low (standing still in mid-air is more likely to get you shot down than to provide any tactical advantage), which is one reason why full 3D vectoring hasn't been added to U.S. fighters (there was some talk about applying the systems seen on the F-15 ACTIVE and F-16 VISTA to combat planes, but nothing serious ever came of it, and most of those airframes are now slated for retirement).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-26T23:28:36.863" LastActivityDate="2015-06-26T23:28:36.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16290" PostTypeId="2" ParentId="16268" CreationDate="2015-06-25T16:07:33.347" Score="3" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;An aircraft traditionally has three &quot;degrees of freedom&quot; in aerodynamic maneuverability; pitch, yaw and roll. The number of &quot;dimensions&quot; of thrust vectoring relates directly to how many degrees of freedom can be manipulated using only the vectored engine thrust. Therefore, 2D vectoring allows control over two degrees of freedom (typically pitch plus either roll or yaw) while 3D controls all three.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As previously mentioned, the difference between 2D and 3D is the number of degrees of freedom that can be controlled using thrust vectoring.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes, there is such a thing as 1D thrust vectoring. It was seen on early-block F-22s, whose thrust-vectoring nozzles can redirect thrust only up or down, and on these early blocks the nozzles of the two engines moved together in the same direction. Later F-22s (and I believe a retrofit of earlier ones) allowed the nozzles to move independently which also granted roll control using thrust vectoring, making the system 2D. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The F-16 VISTA tech demonstrator allowed vectoring of the engine's thrust in any direction behind the aircraft, but because the aircraft was single-engined and used a system based on the engine's existing &quot;turkey feathers&quot; (which allow the engine to regulate internal combustion pressure and exhaust velocity by restricting the diameter of the nozzle), the craft did not have roll control in a post-stall situation. Later single-engined experimental craft like the X-31 used a different vectoring system with paddles behind the engine exhaust, which can be rotated as well as pivoted allowing thrust to be vectored in a &quot;spiral&quot; fashion, providing roll control and thus full 3D vectoring from a single engine.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-21T16:48:22.580" LastActivityDate="2015-09-21T16:48:22.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16291" PostTypeId="1" AcceptedAnswerId="16295" CreationDate="2015-06-25T16:50:42.423" Score="7" ViewCount="752" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_vectoring&quot; rel=&quot;noreferrer&quot;&gt;Thrust vectoring&lt;/a&gt; is used to extend the manoeuvrability of aircraft outside a `normal' flight envelope, by providing (optionally differential) vectored engine thrust, as explored in many previous questions (&lt;a href=&quot;https://aviation.stackexchange.com/questions/16267/does-3d-thrust-vectoring-tvc-provide-improved-maneuverability-over-2d-tvc&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/16268/what-is-2d-and-3d-thrust-vectoring&quot;&gt;this&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is the direction of vectoring actually controlled by the pilot during flight? Does a flight control computer automatically interpret &quot;traditional&quot; control surface inputs under extreme conditions and move the nozzles appropriately to create the desired effect? Or is vector direction a separately controllable interface? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've noticed in my flight sim of choice, XPlane, that the configuration panel allows the mapping of an analogue axis on my joystick/pedal setup to 1D vectored thrust. I've no idea if this is representative of any real fast jets, but if it is, it seems that this approach could create a lot of extra &quot;pilot workload&quot; -- given that it's another one (to three!) control axes to be manipulated -- and manipulated at the same time as pulling potentially very aerobatic manoeuvres with little room for mistakes. This seems like a Bad Idea. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, it might be the case that independently controlled vectored thrust allows for a wider range of aircraft manoeuvres than that which could traditionally be 'expressed' by control surface movements alone. Giving fast jet pilots the extra workload would, therefore, be worth the risk. &lt;/p&gt;&#xA;" OwnerUserId="7499" LastEditorUserId="65" LastEditDate="2015-06-25T17:31:14.447" LastActivityDate="2019-12-04T01:44:04.957" Title="How is thrust vectoring controlled by the pilot?" Tags="&lt;military&gt;&lt;thrust-vectoring&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16292" PostTypeId="1" AcceptedAnswerId="16293" CreationDate="2015-06-25T17:40:00.083" Score="13" ViewCount="5150" Body="&lt;p&gt;According to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12956/what-are-different-types-of-weights-of-an-aircraft&quot;&gt;this question's&lt;/a&gt; answers, &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;MTOW&lt;/a&gt; (or MTOM) is the Maximum Take Off Weight, which is everything up to and including trip fuel. Then there is one step above that, &lt;a href=&quot;http://en.wikipedia.org/wiki/Maximum_ramp_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;MRW&lt;/a&gt;, or Maximum Ramp Weight, which is &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;MTOW&lt;/a&gt; plus fuel used to taxi out to take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can a plane be given too much roll-out fuel, so as the plane is actually too heavy to take off, without having to do perhaps another lap around the airport?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My thoughts are that there are simply no scheduled flights which require a total amount of trip fuel that would make roll-out fuel cause the plane to be too heavy for take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Although (in a comment) I am asked to possibly change the title of the question to fit more closely (include fuel), after considering it, I've decided to leave it alone. It is unlikely that a plane would be loaded to the point that it is too heavy to take off, before fuel is added. I believe it would be a 100% certainty that it was the addition of fuel that will make (all)(commercial) aircraft go beyond MTOW. There might be some edge cases of contents (payload) being too heavy, but if that were the case the plane would not even be considered for take off (without fuel).&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-05-24T02:33:38.990" Title="Can a commercial airliner be too heavy to take off?" Tags="&lt;commercial-aviation&gt;&lt;takeoff&gt;&lt;fuel&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16293" PostTypeId="2" ParentId="16292" CreationDate="2015-06-25T17:50:59.260" Score="21" Body="&lt;p&gt;It is possible to arrive at the runway with too much weight to takeoff, but this result is generally a mismanagement of fuel.  The most likely scenario this happens is when you are going to be at MGTOW for takeoff but need fuel to get to the runway (putting you over MGTOW at the gate) and are anticipating a long taxi or long lines at a de-ice pad. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the long taxi doesn't materialize this can result in getting to the runway with too much fuel.  Recognizing this, fixing it is often as simple as taxiing with both engines instead of just one.  If you are really overweight you just ask to get put somewhere you can wait while running both engines and wait for the weight to come down.  There is really no benefit to taxiing around the airport versus just waiting in one spot to burn fuel.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2015-06-26T04:49:38.387" LastActivityDate="2015-06-26T04:49:38.387" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16295" PostTypeId="2" ParentId="16291" CreationDate="2015-06-25T18:24:04.633" Score="6" Body="&lt;p&gt;Thrust vectoring isn't controlled by the pilot directly, except being able to turn it on or off in various circumstances. If it is on, the aircraft computers control the vectoring based on external conditions, the state of the aircraft and control input. &lt;/p&gt;&#xA;" OwnerUserId="8166" LastActivityDate="2015-06-25T18:24:04.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16296" PostTypeId="1" AcceptedAnswerId="16301" CreationDate="2015-06-25T18:25:01.753" Score="10" ViewCount="3010" Body="&lt;p&gt;Wikipedia says that because of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;area rule&lt;/a&gt;'s impact on wave drag:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;aircraft have to be carefully arranged so that at the location of the wing, the fuselage is narrowed or &quot;waisted&quot;, so that the total area doesn't change much.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This much makes sense to me. Though it's a bit difficult to tell, I understand that in the picture supplied there, the green circle toward the front of the aircraft is intended to have roughly the same area as the blue circle and lines through the wing cross-section:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Area_rule_unifilar_drawing.svg/1280px-Area_rule_unifilar_drawing.svg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Area_rule_unifilar_drawing.svg/1280px-Area_rule_unifilar_drawing.svg.png&quot; alt=&quot;Wikipedia&amp;#39;s area rule example plane&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sub&gt;All images from &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_rule&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; unless otherwise noted&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is more clear in the picture of the &lt;a href=&quot;https://en.wikipedia.org/wiki/F-106_Delta_Dart&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-106 Delta Dart&lt;/a&gt; where one can easily see the &lt;a href=&quot;https://en.wikipedia.org/wiki/Coca-Cola#Contour_bottle_design&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coke bottle&lt;/a&gt; waist where the wings near their widest:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Eclipse_program_QF-106_aircraft_in_flight%2C_view_from_tanker.jpg/1024px-Eclipse_program_QF-106_aircraft_in_flight%2C_view_from_tanker.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Eclipse_program_QF-106_aircraft_in_flight%2C_view_from_tanker.jpg/1024px-Eclipse_program_QF-106_aircraft_in_flight%2C_view_from_tanker.jpg&quot; alt=&quot;F-106!&quot;&gt;&lt;/a&gt;&lt;sub&gt;That's an awesome picture! You could stare at it all day, couldn't you?&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%c3%a4mpf&quot;&gt;Peter Kämpf&lt;/a&gt; even provides a nice explanation of the area rule in his &lt;a href=&quot;https://aviation.stackexchange.com/a/7454/5517&quot;&gt;answer here&lt;/a&gt; including a drawing from the Junkers patent on the subject:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K1a8X.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K1a8X.png&quot; alt=&quot;Junkers patent picture&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sub&gt;Image posted by Peter in his answer, referenced above&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this image, I can see how the areas through several lines across the fuselage, wings &amp;amp; engines are all intended to be (roughly) equal.&#xA;&lt;hr&gt;&#xA;What I &lt;em&gt;don't&lt;/em&gt; understand is how this is applied to airliners like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A380&lt;/a&gt; which they say is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;showing obvious area rule shaping at the wing root&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;in reference to this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/3/30/A380_singapore_airlines_takeoff_arp.jpg/1280px-A380_singapore_airlines_takeoff_arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/3/30/A380_singapore_airlines_takeoff_arp.jpg/1280px-A380_singapore_airlines_takeoff_arp.jpg&quot; alt=&quot;An A380&amp;#39;s soft, vulnerable underbelly&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me, it appears that the cross-section at the wing root consists of the same area at the front of the plane (roughly behind the cockpit appears to be where maximum diameter is achieved), &lt;em&gt;plus&lt;/em&gt; the area of the wing root, &lt;em&gt;plus&lt;/em&gt; the area through the wing, &lt;em&gt;plus&lt;/em&gt; the area through a pair of engines (depending on exactly where you make the cross section). As I see it, there's no slimming of the body to make the area through the wing cross section equal to the area of the cross section just behind the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shot from above of &lt;a href=&quot;http://www.airliners.net/photo/Singapore-Airlines/Airbus-A380-841/1885997/L/&amp;amp;sid=6f3f974759ca988b5a21a36eaa31b081&quot; rel=&quot;nofollow noreferrer&quot;&gt;another&lt;/a&gt; A380 shows that there is no &lt;code&gt;Coke bottle&lt;/code&gt; waist near the wings:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/5/57/Singapore_Airlines_Airbus_A380_Wallner.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/5/57/Singapore_Airlines_Airbus_A380_Wallner.jpg&quot; alt=&quot;A380 from above&quot;&gt;&lt;/a&gt;&#xA;&lt;hr&gt;&#xA;Am I not seeing this correctly, or do I not understand the area rule correctly?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-07-14T08:32:45.273" Title="How is the area rule applied on airliners like the A380?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16298" PostTypeId="1" AcceptedAnswerId="16299" CreationDate="2015-06-25T19:14:45.100" Score="6" ViewCount="884" Body="&lt;p&gt;In the commercial side, who determines the fuel load required for any given flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PIC/Captain? Company/Airline? FBO/Airport?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-06-25T21:18:44.810" Title="Who determines the fuel load?" Tags="&lt;commercial-aviation&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16299" PostTypeId="2" ParentId="16298" CreationDate="2015-06-25T19:24:42.530" Score="7" Body="&lt;p&gt;Disclaimer: this answer applies to airlines (operating under 14 CFR 121) but does not encompass all of commercial aviation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dispatcher that is working your flight plans the routing and determines the minimum fuel required from takeoff to destination to furthest alternate with additional fuel as required by regulation you operate under.  On top of this, contingency fuel is added which can account for enroute diversions, cruising at a different altitude, un-forecast winds, holding, etc.  The total of this fuel is the &quot;release fuel&quot; and you cannot takeoff below this number.  On top of this, extra fuel will be added for taxi time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, it is the captain's responsibility to decide how much fuel is needed.  For slight increases, airline policy may allow captain's discretion to add fuel.  For larger increases in the fuel order you generally need to call the dispatcher and amend the release -- after convincing the dispatcher you need the fuel.  If you decide you need less fuel (e.g. less contingency fuel) you always need to amend the release so you can legally take off.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-06-25T21:18:44.810" LastActivityDate="2015-06-25T21:18:44.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16300" PostTypeId="2" ParentId="16296" CreationDate="2015-06-25T19:35:47.497" Score="3" Body="&lt;p&gt;On airliners it is applied via the use of &lt;a href=&quot;https://aviation.stackexchange.com/questions/7955/what-is-the-purpose-of-the-sharp-pods-under-airliner-wings&quot;&gt;these sharp pods under wings&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A coke-bottle-like fuselage would be extremely impractical for internal arrangement and cargo loading, so it is not done on airliners even though it could probably improve the efficiency a bit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is done is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engines shifted ahead of the wing help smooth out the increase of cross-sectional area around the wing leading edge.&lt;/li&gt;&#xA;&lt;li&gt;The enlarged flap track fairings, a.k.a. anti-shock bodies help smooth out the decrease of cross-sectional area around the wing trailing edge.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-06-25T19:35:47.497" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16301" PostTypeId="2" ParentId="16296" CreationDate="2015-06-25T19:46:14.337" Score="8" Body="&lt;p&gt;First of all, not the area should be equal, but the area gradient along the direction of flow should be shallow. The minimum drag with a given volume can be achieved when the area distribution is &lt;a href=&quot;https://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body&quot; rel=&quot;nofollow noreferrer&quot;&gt;that of a Sears-Haack body&lt;/a&gt;. Ideally this rule applies &lt;a href=&quot;https://aviation.stackexchange.com/questions/6331/supersonic-fuselage-design/6339#6339&quot;&gt;only at Mach 1&lt;/a&gt;, and once you go faster, the cross sections which matter are those along a Mach cone, not those of the aircraft's cross section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For subsonic flight, the penalty for neglecting the area rule is small; it only matters when local flow is supersonic ahead of a contraction of the contour of the aircraft. Subsonic flow would decelerate, whereas supersonic flow will accelerate further and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=6%7C0.1003#5055&quot;&gt;result in a drag-intensive shock&lt;/a&gt; downstream. Adding something to fill up the contraction will reduce the pressure gradients and ideally avoid the shock. By this, area ruling will help to shift the onset of the Mach-related drag rise and enables airliners to cruise a little faster. Honestly, I cannot see the &quot;obvious&quot; area rule shaping on the A380 - to me this is classic subsonic aerodynamics which tries to avoid sharp pressure gradients in the area of the wing airfoil's rear loading. Especially the outer engine pylons could be done better, but I digress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airliners, it is much more important to have a constant fuselage cross section, which makes stretching the fuselage simpler and is much easier to build. Area-ruling the fuselage simply is not worth it (yet) when your maximum cruise speed is just Mach 0.85. It is enough to add some &lt;a href=&quot;https://commons.wikimedia.org/wiki/Category:Anti-shock_bodies&quot; rel=&quot;nofollow noreferrer&quot;&gt;Küchemann bodies&lt;/a&gt; to smooth out pressure gradients.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a comparison of a swept wing at Mach 0.9, on the left clean and on the right with Küchemann bodies. Note the massive flow separation on the left wing, whereas the flow pattern on the right wing shows attached flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zBeue.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zBeue.jpg&quot; alt=&quot;Mach 0.9 wing comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mach 0.9 wing comparison (picture &lt;a href=&quot;http://www.aerospaceweb.org/question/aerodynamics/area-rule/mach09-oil-vis.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-11-06T08:41:56.787" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16302" PostTypeId="2" ParentId="14898" CreationDate="2015-06-25T20:05:42.530" Score="2" Body="&lt;p&gt;Some of this depends on what you are flying as well, but as a rotorcraft pilot, we tend to fly at a lower altitude than planes. The number one killer of helicopter pilots is wire strikes. Wires, although they may seem obvious when you're on the ground, are next to impossible to see from the air. They're incredibly difficult to see both because the background is now the ground instead of the sky, and because you are likely to be quite a distance away (and if you aren't, its probably too late to do anything about it. You're either going to hit it, or not). You're also going to get quite a bit of mechanical turbulence, meaning turbulence that is caused by the wind blowing against things on the ground. Buildings, for example, will have air blowing upwards on one side of the building, and air blowing downwards on the opposite side. This air turbulence can extend quite a distance up from the object itself.  This will be true for buildings, hills, mountains, etc. In the case of a plane, you're also going to get reduced performance (in most cases) because the air is denser, and you'll have higher drag. Helicopters have the opposite effect, where they become more efficient with higher air density, so they'll fly better near the ground and at low altitudes.&lt;/p&gt;&#xA;" OwnerUserId="2359" LastActivityDate="2015-06-25T20:05:42.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16303" PostTypeId="2" ParentId="15269" CreationDate="2015-06-25T20:13:37.500" Score="13" Body="&lt;p&gt;It's primarily a question of pilot workload and military policy at design time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll notice that the primary two-seat fighters and attack planes in the U.S. armed forces (designation F or A) were designed in the late Korean through Vietnam eras, representing the third and early fourth generation of fighter design. This was a critical period of transition from the fighter philosophy of the World Wars and Korea, primarily day fighters engaging in visual-range combat with guns, to modern air combat involving all-weather precision engagements beginning BVR through use of radar, missiles and targeting computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As these systems were added to fighter cockpits in the early &quot;century series&quot;, developing what would eventually be known as the &quot;multirole fighter&quot;, pilot workload grew dramatically compared to the relatively simple layouts and weapons systems of propeller and early jet dogfighters. As a result, these systems, intended to increase pilot situational awareness, ended up doing the exact opposite, forcing the pilot to keep his head &quot;in the cockpit&quot; reading gauges and displays, with his situational awareness of what was going on outside the plane somewhere around his ankles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the problem identified but insufficient technology to take critical &quot;heads-down&quot; tasks like navigation away from the pilot, designers initially addressed it by adding a second crewman, whose job it would be to handle tasks not directly associated with the primary operation of the plane, such as navigation, managing the radar, keeping an extra pair of eyes on the sky around them, handling radio communications, etc. This guy is officially known in most situations as the Radar Intercept Officer or RIO, or informally as the GIB (Guy In Back).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would take a few more technological developments, like the inertial navigation system, heads-up display, HOTAS control layouts, the integrated fire control computer, and advanced C4I capability like AWACS/JSTARS, before the workload inherent in the average fighter sortie could reasonably be handled by one crewman. AWACS can guide and advise pilots much like civilian ATC, the inertial navigation system allows pilots to simply point their plane in the indicated direction as opposed to monitoring nav beacons to figure out exactly where they were, and the HUD and HOTAS got the pilot's head out of the cockpit by placing the information and controls he needs to fly the jet effectively in combat where they're supposed to be; right in front of him and/or at his fingertips. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary fighter and attack jets of the third and fourth generation to utilize a 2-man crew include the F-4 Phantom, F-111 Aardvark, A-6 Intruder, the F-14 Tomcat, and the B and D variants of the F-15 Eagle, F-16 Falcon and F-18 Hornet. Notice by the development of the F-15 through F-18 that designers and US top brass were already considering single-seaters to be sufficient; the development and integration of the aforementioned systems into U.S. fourth-generation fighters had successfully made the workload presented by the plane more manageable by one person, thus the backseater (who required expensive flight training just like the pilot) could be moved to a second plane as pilot instead of riding along in the first, and the B/D variants of the Eagle, Falcon and Hornet were primarily used as trainers. However, all these designs were laid out in both one and two-seat variants just in case; the next fighters developed domestically for the USAF, the F-22 and F-23, were single-seat only (at least one two-seat F-22B was built, whether as a trainer or preproduction evaluation model, but the USAF never seriously considered a two-seater). The F-35 was never even proposed as a two-seater, primarily because every cubic inch of the design is spoken for especially in the STOVL-capable B variant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The remaining two-seat fighters in the U.S. arsenal are the F-15E strike fighter (the backseater having the unique title of &quot;Weapons Systems Officer&quot; or &quot;Wizzo&quot; and being responsible for the fairly complex radar and targeting systems aboard) and variants of the F/A-18 including the F-variant &quot;Super Hornet&quot; and G-variant &quot;Growler&quot; EW fighter. In all these cases the GIB usually manages the advanced radar, targeting and jamming systems of these craft, as well as assisting in dogfighting by providing a second set of eyes especially behind the aircraft. The EA-6B Prowler, an older EW aircraft replaced just this year with the EA-18G Growler, had a crew of four; one pilot and three countermeasures officers.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-08T21:37:37.680" LastActivityDate="2015-10-08T21:37:37.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16304" PostTypeId="2" ParentId="16116" CreationDate="2015-06-25T20:24:59.320" Score="9" Body="&lt;p&gt;This was one of the primary problems that needed to be solved in helicopter flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my example, I'll use a 2 bladed helicopter, but this holds true with all helicopters, and I'll explain some of the different rotor types later on. The blade that is moving forward, relative to the direction of the helicopter, is called the advancing blade. The opposite is called the retreating blade, and you are correct in assuming that they would generate different amounts of lift. As a previous commenter noted, the term used for this is &quot;dissymmetry of lift&quot;, and is the same thing that limits the maximum speed of a helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A two bladed helicopter will generally have what is called a &quot;semi-rigid&quot; rotor system. Semi rigid systems are only possible on even bladed helicopters, and are generally only used on 2 bladed helicopters. The two blades are connected together by a hinge on the rotor hub (where the blade meets the helicopter), and if you push down one blade, the other blade moves upward, and vise versa. What happens as you move forward is that the advancing blade (the one generating more lift) will get pulled up with a greater force than the retreating blade (the one generating less lift). As the advancing blade rises up (because of its additional lift), it pushes the retreating blade down. This advancing blade, in pushing up the rotor, is reducing the angle of attack of the blade against the airflow, which in turn is going to reduce its lift. The retreating blade is hinging downwards, which is increasing its angle of attack against the airflow, which will increase the lift it provides. These two forces will work against each other until they are in balance, which means that the advancing blade and the retreating blade will even out in the lift they are generating, which removes the dissymmetry of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades in a helicopter are spinning at a some speed, which varies depending on where on the blade you are talking about (the tip or near the rotor hub, for example), but to simplify this explanation, I'm going to assume that the blade is traveling at the same speed along its entire length. Let's say that the blade is spinning around at 100mph at its tip. As the helicopter moves forward, at let's say 50mph, then we have one blade that is moving against the air at 150mph (the advancing blade), and one that is moving against the air at 50mph (the retreating blade). As the helicopter gets closer to 100mph (the speed of the blades), at some point, the speed of the air against the retreating blade will get closer and closer to 0. When it hits 0, it will stop generating lift, and the helicopter will start to roll (now the rotor is only generating lift on one side). This effect, called retreating blade stall, is one of the reasons why helicopters are limited in their top speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just as a side note, I have greatly simplified some of these explanations, so I am well aware that I have glossed over various parts of this explanation to simplify it.&lt;/p&gt;&#xA;" OwnerUserId="2359" LastActivityDate="2015-06-25T20:24:59.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16305" PostTypeId="2" ParentId="11731" CreationDate="2015-06-25T20:37:46.327" Score="3" Body="&lt;p&gt;The R-22 helicopter has both cyclic/collective friction, as well as a trim. When you are hovering, you are using a lot of tail rotor to counteract the spinning of the blade, and there isn't any force to counteract it. The tail rotor, while countering your rotation, will also push you in a direction (like a propeller), so in a hover, with a helicopter that has a counter clockwise rotation, the tail rotor will keep pushing you to the right. To counter that, you have to put in left cyclic. To help reduce the effort required to keep it a hover, Robinson put in a trim, which just adds a constant left input to the cyclic. This greatly reduces the workload for the pilot while taxiing and hovering. The amount of trim, in the case of Robinson helicopters, is not pilot adjustable, but it is a trim setting, technically speaking, which is separate from the friction settings, which helicopter pilots can/do use in the same way fixed wing pilots would use a &quot;trim&quot;. For example, I've used the cyclic/collective friction settings in the R-22 to tighten up the movements of the cyclic and collective. This makes it much easier to read a navigation map or use the radio. It allows me to take my hands off some of the controls for a whole second or two to allow me to adjust a map or tune the radio :)&lt;/p&gt;&#xA;" OwnerUserId="2359" LastActivityDate="2015-06-25T20:37:46.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16306" PostTypeId="2" ParentId="16292" CreationDate="2015-06-25T20:47:18.270" Score="5" Body="&lt;p&gt;Correct on virtually all points; it is possible for an aircraft with high payload or long range expectations to require more fuel be loaded at the gate than it could make it off the runway carrying; however, it wouldn't have to lift off with any fuel it needs to burn just to get to (or even down) the runway. The amount of extra fuel needed would be marginal; a couple hundred pounds at most, just a few minutes' worth at anything more than idle power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're also correct that the operator of the plane wouldn't be too eager to test these maximums with any fleet aircraft, and will have their own more conservative guidelines for loading an aircraft. These guidelines are typically only approached by cargo jets; people are relatively low-density given the amount of cabin volume required for each passenger. But, such limits are the reason, for instance, behind airline policies on number of checked bags (and the cost of each one) and the maximum weight of each one; more bags, and/or heavier ones, increase fuel requirements.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-25T20:47:18.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16307" PostTypeId="1" AcceptedAnswerId="16308" CreationDate="2015-06-25T21:02:22.793" Score="28" ViewCount="22650" Body="&lt;p&gt;Other questions currently being answered cover situations regarding planes near, at or even above their MTOW. It raises a more basic question: how is the exact &quot;ramp weight&quot; of an airliner measured or estimated?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On most airlines, luggage is weighed and counted, so the pilot would know within 100lbs or so how much mass is in his cargo hold. He'd also know the &quot;operating empty weight&quot; of the plane itself (the weight of the airframe, all fluids besides usable fuel and the weight of the crew), and the mass of the fuel he's taking on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest variable, then, is the weight of the passengers and their carryons/personal effects. Last time I flew, I wasn't knowingly weighed and neither was anyone else getting on with me. So, while you know the number of passengers, the total &quot;cabin weight&quot; is a big unknown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, do planes have load sensors in their gear which could be used to exactly measure the plane's ramp weight? Or is a median passenger and carryon weight used, with a more conservative total passenger rating used in case a few planeloads err on the heavy side of the bell curve?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-25T21:53:20.823" LastActivityDate="2016-05-21T21:30:13.287" Title="How does a commercial airliner measure its weight/mass?" Tags="&lt;weight-and-balance&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16308" PostTypeId="2" ParentId="16307" CreationDate="2015-06-25T21:56:49.630" Score="45" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Determination of &lt;em&gt;mass and balance&lt;/em&gt; (or weight and balance) is a critical task for the crew, an error in this operation may have tragic consequences. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Weighing passengers and carry-on items is mandatory per regulation.&lt;br&gt;&lt;br&gt;&#xA;Either standard predetermined weights, or actual weights can be used in this operation. Airlines usually use predetermined tables. Tables values take into account different types of travel (e.g. regular and charter).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;While the weight must be checked, the center of gravity location is of equal importance. The distribution of the passengers in the aircraft is also taken into consideration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft are not weighed prior to each flight, but the basic empty weight must be known and checked periodically per regulation.&lt;br&gt;&lt;br&gt;&#xA;Aircraft are weighed simply using scales under the carriages :-)&lt;br&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/yJ53m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://blog.klm.com/how-do-you-weigh-a-plane-jesseyknows/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;br&gt;&lt;br&gt;&#xA;The other method is to use jacks. See further below for an image.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;So this was the short answer. To understand why and how to balance the aircraft, there are quite a lot elements to introduce. For those interested, just continue!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weight...&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The different elements composing the takeoff weight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/65XjJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/65XjJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these elements must be determined prior to taxi and takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mass of these elements are necessary to check that the different maximum weights are not exceeded. However there is another aspect of the masses which needs to be secured: Where are the masses located?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Taking &lt;strong&gt;KeithS&lt;/strong&gt;' example, if there are many heavy people grouped in the forward section, we may have a problem at &lt;a href=&quot;http://www.skybrary.aero/index.php/Vr&quot; rel=&quot;noreferrer&quot;&gt;Vr&lt;/a&gt;, even if the &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;noreferrer&quot;&gt;MTOW&lt;/a&gt; is not exceeded.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;... and balance. Location of the center of gravity vs. the MAC&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The masses must be distributed so that the center of gravity of the aircraft is located within limits determined relatively to the aerodynamic chord, and the center of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is required to ensure the stability and the maneuverability, to minimize the efforts on the horizontal and vertical stabilizers and to increase the maximum lift and reduce the drag. On airliners, the center of lift must be located between the CG and the center of lift of the horizontal stabilizer, so that the latter pushes downward to balance the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ABobH.gif&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On airliners the width of the wing is greatest where it meets the fuselage at the wing root and progressively decreases toward the tip. As a consequence, the chord also changes along the span of the wing. The average length of the chord is known as the mean aerodynamic chord (&lt;a href=&quot;http://www.skybrary.aero/index.php/Mean_Aerodynamic_Chord_%28MAC%29&quot; rel=&quot;noreferrer&quot;&gt;MAC&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/24dY2.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;The MAC is a portion of the wing, delimited by LeMAC (leading, 0%) and TeMAC (trailing, 100%). The CG must be located in the MAC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In large aircraft, center of gravity limitations and the actual center of gravity are often expressed in terms of %MAC (on the roll axis, similar limits exist on the two other axis). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iDK5G.png&quot; alt=&quot;enter image description here&quot;&gt;&#xA;(image and text around: &lt;a href=&quot;https://books.google.com/books/about/Aircraft_Design.html?id=VT-Tc3Tx5aEC&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Design, Mohammad H. Sadraey&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, in large transport aircraft, the most forward CG is located as forward as 5% MAC, while the most aft location as aft as 40% MAC. The average CG limits in large transport aircraft are between 20 and 30% MAC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As commented by &lt;strong&gt;Calchas&lt;/strong&gt;, using wrong weights for the passengers (adults instead of children) may move the CG to a wrong location, not balanced by the trim, and create strong difficulties during the takeoff and the initial climb.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PAX weight applicable procedures&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an airliner, the PAX portion is relatively small compared to the total mass, so the passengers mass is usually estimated based on standard passenger mass tables and the number of PAX per cabin section. Each airline may provide its own standard mass tables, but standard tables are proposed with the applicable regulation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/JAR-OPS_1&quot; rel=&quot;noreferrer&quot;&gt;JAR-OPS1&lt;/a&gt; or EU-OPS1 for Europe (section &lt;a href=&quot;http://aircraft-support.blogspot.fr/2009/09/aircraft-weighing-jar-ops-16.html&quot; rel=&quot;noreferrer&quot;&gt;JAR - OPS 1.620 Mass values for passengers and baggage&lt;/a&gt;). Values valid in 2008:&lt;br&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/v7ATl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9yoZS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/OE8F8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.dac.public.lu/documentation/procedures_ops/OPS1_EN.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;br&gt;&lt;br&gt;&#xA;Those tables have been establish using airlines data obtained by surveys. They are updated from time to time.&lt;br&gt;&lt;br&gt;&#xA;In case the operator wants to establish their own equivalent tables, &lt;a href=&quot;http://aircraft-support.blogspot.fr/2009/09/aircraft-weighing-jar-ops-16.html&quot; rel=&quot;noreferrer&quot;&gt;JAR - OPS 1.620&lt;/a&gt; provides a detailed operating mode to sample passengers and weigh them.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the EU, a new survey was conducted by the European Aviation Safety Agency in 2009 and a proposal for table updates issued:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://easa.europa.eu/system/files/dfu/Weight%20Survey%20R20090095%20Final.pdf&quot; rel=&quot;noreferrer&quot;&gt;Passenger and Baggage weight survey&lt;/a&gt;&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/NFLwk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At this point you may want to download the documentation I'm mostly using for this post: &lt;a href=&quot;http://www.mmo.org.tr/resimler/dosya_ekler/af82af3a84ced38_ek.pdf?tipi=68&quot; rel=&quot;noreferrer&quot;&gt;Mass and Balance in Aircraft&lt;/a&gt;. We are at page 54.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Special cases&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are cases where it is obvious the actual mass and balance will be erroneous if the standard tables are used (this is especially true for a small cabin).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these cases the operator must improve the evaluation by actual weighing of either all or a sample of passengers and their baggage. The procedure already mentioned for establishing standard tables is used (&lt;a href=&quot;http://aircraft-support.blogspot.fr/2009/09/aircraft-weighing-jar-ops-16.html&quot; rel=&quot;noreferrer&quot;&gt;JAR - OPS 1.620&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Putting all elements together&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All masses, arms (distance to the reference center) and &lt;a href=&quot;https://en.wikipedia.org/wiki/Moment_%28physics%29&quot; rel=&quot;noreferrer&quot;&gt;moments&lt;/a&gt; are finally reported on the aircraft manifest to calculate the correction that must be used for the takeoff (trim amount).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IBuki.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Basic empty weight determination&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is not weighed for each takeoff, still it has been weighed to determine its basic empty weight and its center of gravity. This operation must be done every 3 or 4 years (9 or 18 years in a large fleet, this is a specific process) according to JAR Ops 1.605, Appendix 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Platform scales under the carriages may be used:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fic8v.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://precisionscale.com/rentals/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another method is to use jacks equipped with a transducer at their top:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/90mME.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.aviationpros.com/article/10239992/airframe-technology-to-weigh-an-aircraft&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related FAA regulations and JAR-OPS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FAA AC 120-27E and JAR-OPS 1.620 to determine the mass of the baggage, passengers and carry-on items.&lt;/li&gt;&#xA;&lt;li&gt;FAA AC 120-27E, JAR-OPS 1.607, JAR-OPS 1.615 for the determination of operational items, which include the crew and the crew baggage (there is also a table, that I won't include to prevent comments on the differences with the passenger table -- All tables are based on survey from airlines). The operational items also include catering, emergency equipment, spare parts..&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;May be interesting too:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is a confirmed trend of weight increase among the population (including myself). This has an impact on the operational costs. The way airlines manage this impact can be read in a two-part article: The true costs of heavier passengers, &lt;a href=&quot;http://www.aircraftinteriorsinternational.com/articles.php?ArticleID=422&quot; rel=&quot;noreferrer&quot;&gt;part 1&lt;/a&gt;, &lt;a href=&quot;http://www.aircraftinteriorsinternational.com/articles.php?ArticleID=424&quot; rel=&quot;noreferrer&quot;&gt;part 2&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1850/do-some-airplanes-have-weighing-scales-on-the-landing-gear&quot;&gt;Do some airplanes have weighing scales on the landing gear?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1987/do-airlines-weigh-passengers-and-baggage-before-loading-the-aircraft&quot;&gt;Do airlines weigh passengers and baggage before loading the aircraft?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/22340/how-much-time-does-it-take-to-calculate-the-leveling-and-weighing-of-big-and-sma?lq=1&quot;&gt;How much time does it take to calculate the leveling and weighing of big and small aircraft?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-05-21T21:30:13.287" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16309" PostTypeId="2" ParentId="16242" CreationDate="2015-06-25T22:30:49.657" Score="4" Body="&lt;p&gt;No, &lt;em&gt;assuming&lt;/em&gt; the wing geometry and the coefficient of friction of the material on the surface of the wing do not change. So, swapping a section of aluminum or carbon fiber skin on the wing for a section of Plexiglas or silicate glass under which you place the solar cells will, all other things being equal, have a negligible effect on drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, doing something like this, all other things are not necessarily equal. First off, the border between the normal skin material and the solar cell cannot be a &lt;em&gt;perfectly&lt;/em&gt; smooth transition; at some level of magnification, there will be a noticeable seam which will reflect as an increase in the surface &quot;roughness&quot; of the with with solar cells compared to the one without. While nonzero, it's likely negligible if the parts of the wing are well-fitted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, there will likely be a change in mass when removing a thin layer of aluminum, carbon fiber or polymer sheathing, and replacing that with Plexiglas with solar cells underneath (plus the power wiring, converters and other additional components that otherwise wouldn't need to exist). Classically, that has no effect on drag, but it will change momentum calculations which affect how much the drag matters, and also as was stated, heavier masses require higher angles of attack to increase lift and counter weight, which increases induced drag as the effective shape of the airfoil slicing through the air changes to present a larger cross-section. Wing stress moments will also be affected as the weight distribution of the plane between fuselage and wings has changed, and this can change the amount of effective dihedral due to wing loading under various conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, there will be a nonzero difference in surface roughness between the majority of the skin or sheathing and the solar cells. For instance, a matte finish as some aircraft have is rough by definition to provide different reflective planes to scatter light. You want a highly polished surface on the solar cells to minimize energy loss through the outer layer. Even if most of the aircraft is finely polished, there's a difference in how fine a polish various materials can take; the harder the surface, the easier it is to take a fine polish.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-25T22:30:49.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16310" PostTypeId="2" ParentId="129" CreationDate="2015-06-25T22:46:31.967" Score="4" Body="&lt;p&gt;The major ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Run &lt;em&gt;really fast&lt;/em&gt; into the wind at minimum angle of attack and then pull up a bit, and you'll get a little lift that you might then use to find a thermal. This is very location-dependent, and you're unlikely to fly very long at a stretch.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Get a tow from a car or a powered plane like a sailplane would. A car limits your altitude, but is cheap and easy to set up; arranging a pull pilot is a bigger deal but can get you hundreds of feet in the air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tether yourself to the ground with a long rope, push the control bar forward and rise up in the air like a kite. Then, cut yourself loose, pull the control bar into your stomach and cut around in a spiral to gain forward airspeed before leveling off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most hang gliding I've seen done has involved launching from a tall hill or cliff, then looking for a ridge or thermal updraft nearby to keep you in the sky.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-25T22:46:31.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16311" PostTypeId="1" CreationDate="2015-06-25T22:55:27.137" Score="4" ViewCount="148" Body="&lt;p&gt;I have been having a conversation at the office about whether to use ground control when using drones/UAVs to capture aerial images. The ground control that I am referring too is any &lt;a href=&quot;https://www.business.qld.gov.au/industry/titles-property-construction/surveying/permanent-survey-marks&quot; rel=&quot;nofollow&quot;&gt;permanent survey markers&lt;/a&gt;, or &lt;a href=&quot;https://en.wikipedia.org/wiki/Real_Time_Kinematic&quot; rel=&quot;nofollow&quot;&gt;Real Time kinematic systems&lt;/a&gt; that would aid in improving the spatial accuracy of the data captured. I would imagine that the level of ground control you would use, would depend on the accuracy that you were trying to achieve. I am not sure if this is an aviation question or more GIS related due to using surveying techniques.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would anyone know if there are any fixed regulation for the use of ground control within Australia?&lt;/p&gt;&#xA;" OwnerUserId="9070" LastEditorUserId="19" LastEditDate="2016-07-04T12:25:57.737" LastActivityDate="2016-07-04T12:25:57.737" Title="Drones photography and ground control regulation" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;australia&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-07-04T17:50:24.340" ContentLicense="CC BY-SA 3.0" />
  <row Id="16312" PostTypeId="1" AcceptedAnswerId="16315" CreationDate="2015-06-25T23:47:02.133" Score="5" ViewCount="2201" Body="&lt;p&gt;I'm looking for the greatest muzzle velocity of a gun on any fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I looked up the GAU-8 Avenger from the A10 Warthog first. Its muzzle velocity is 1,070 m/s, which is pretty darn high (almost 3 times the speed of sound). Are there any faster bullets out there from an aircraft gun?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Don't really care about the firing rate (rounds per minute), or bullet caliber. All I'm looking for is highest muzzle velocity.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2018-04-20T09:04:19.577" LastActivityDate="2018-04-20T09:04:19.577" Title="What is the highest muzzle velocity of a gun on any fighter aircraft?" Tags="&lt;fighter&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16313" PostTypeId="2" ParentId="12308" CreationDate="2015-06-26T00:05:22.877" Score="6" Body="&lt;p&gt;It really depends on the aircraft. Your F-15C as an air superiority fighter would primarily carry missiles; it can carry four AMRAAMs or Sparrows underbelly (the Sparrow's been all but phased out of the arsenal, but was a common loadout in the F-15's heyday) and four Sidewinders on the sides of the wing hardpoints, with either an additional pair of AMRAAMs or Sparrows on the bottom of the hardpoints or two 600-gallon droptanks (useful for extended CAP missions). That's in addition to 650 rounds of Vulcan 20mm. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These missiles are fairly lightweight; each AMRAAM only weighs about 340 lbs (compare to 500, 1000, 2000 or even 5000-lb bombs), to total no more than about 3500 lbs total ordnance weight when loaded for a &quot;scramble interceptor&quot; profile (get in the air quickly, target the enemy and if they close within X miles, fire at will). It's counterproductive for a plane designed to dogfight to be hampered by heavy munitions (when the F-15 was first designed, the aim was a pure air superiority fighter to combat the perceived threat of the MiG-25, and the mantra was &quot;not a pound for air to ground&quot;). Thus, the primary change in mass and balance during a mission is fuel. If the loadout includes droptanks, they'll be consumed first, as they can be jettisoned when empty (or if an aerial threat closes to dogfighting range or a missile is launched) and even if kept for re-use, draining them first increases the aircraft's roll rate faster in preparation for mixing it up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15E ground strike variant is a similar airframe with a very different mentality; the aircraft is able to lift a whopping 49,000 lbs of combined fuel and ordnance. It was designed to replace the F-111 Aardvark as a light penetration fighter-bomber for long-range precision strikes on hardened targets using large laser-guided bombs (missions that generally call for a &quot;one pass and haul ass&quot; mentality by the crew), but the Strike Eagle has also been used for SEAD, tank-plinking and other missions generally requiring more total &quot;drops&quot; and thus a more gradual change in aircraft weight and balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The performance and handling of the aircraft during ingress versus egress is usually totally different. Enroute, a plane full of fuel and ordnance is a slow, lazy-feeling thing that's &lt;em&gt;really&lt;/em&gt; hard to maneuver. By the time you make your approach, though, you've burned over half your fuel, and even with the heaviest bombs this thing can take, fuel is still the majority of the aircraft's max take-off weight. When dropping Mk-82s or laser-guided variants, they typically have to be dropped in pairs; the plane just isn't stable with a one-ton imbalance between the wings (I can't think of many aircraft its size that would be). 500-lb Mk-84s and GBU-12s are still typically dropped in pairs, but it's possible to drop one at a time and keep a stable airframe left to right. The fire control computer on most planes with multiple front-to-back hardpoints, including the F-15, will typically release ordnance front to back, bottom to top, reducing the possibility of the ordnance getting tangled up with others on the way off the aircraft or to the ground (it also helps improve accuracy to use the front stores first as airflow over the weapon is cleaner with nothing in front of it). To maintain weight balance front to back, it is possible to configure the FCC to release from the ends toward the center, but it only matters at all for the F-15E's CFT hardpoints which are in three groups from front to back; it's a bigger deal for a heavy bomber like the B-52, which can carry on external hardpoints running practically the entire length of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, once the ordnance is gone, the F-15E feels like a completely different plane, much more like its air-superiority cousin. The CFTs (and the added targeting pods and the Wizzo's seat) make the F-15E inferior in a dogfight to the C-variant, but it stands a lot more of a chance with a similar loadout versus having almost 15,000 pounds of bombs on the rails.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2016-03-15T21:54:02.500" LastActivityDate="2016-03-15T21:54:02.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16314" PostTypeId="1" CreationDate="2015-06-26T00:41:42.363" Score="5" ViewCount="113" Body="&lt;p&gt;I'm wondering if there is any prevailing organized body of sports-people in hang-gliders, other gliders, and/or personal non-powered glide craft in general?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm particularly interested in stunts related to gliding, competitions, and how to find people in each locale (presumably) thorough an 'organized' body of sports-people.&lt;/p&gt;&#xA;" OwnerUserId="57" LastEditorUserId="2176" LastEditDate="2015-06-26T12:19:11.867" LastActivityDate="2015-10-14T02:05:19.653" Title="Is there a worldwide association for stunt/trick/tournament hang-gliding?" Tags="&lt;glider&gt;&lt;unpowered&gt;&lt;hang-glider&gt;&lt;trainer&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16315" PostTypeId="2" ParentId="16312" CreationDate="2015-06-26T02:31:44.900" Score="9" Body="&lt;p&gt;The muzzle velocity of guns is based on multiple factors and generally sees a wide range. Most importantly how the bullet is loaded (gun powder wise) and what mass the bullet is. For example the P-51 mustang carried 6 &lt;a href=&quot;https://en.wikipedia.org/wiki/M2_Browning&quot; rel=&quot;noreferrer&quot;&gt;50 caliber BMG's (M-2)&lt;/a&gt;. Which (although not available at the time) is capable of accepting the &lt;a href=&quot;https://en.wikipedia.org/wiki/.50_BMG#Military_cartridge_types&quot; rel=&quot;noreferrer&quot;&gt;Caliber .50, Saboted Light Armor Penetrator, M903&lt;/a&gt; round which has a quoted muzzle velocity of 4,000 ft/s (1,219 m/s). It should also be noted that the base muzzle velocity of an M2 is 2,910 ft/s (890 m/s) for &lt;a href=&quot;https://en.wikipedia.org/wiki/.50_BMG#Military_cartridge_types&quot; rel=&quot;noreferrer&quot;&gt;M33 ball round&lt;/a&gt;. So it really depends what round you are loading in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;noreferrer&quot;&gt;F-35 Joint Strike Fighter&lt;/a&gt; has the &lt;a href=&quot;http://www.gd-ots.com/armament_systems/mbw_GAU-22A.html&quot; rel=&quot;noreferrer&quot;&gt;GAU-22 Gatling Gun&lt;/a&gt; which with the TP HEI ammunition has a quoted muzzle velocity of 3,560 feet (1,085m) per second (15 m/s faster than the GAU-8 on the warthog). &#xA;&lt;img src=&quot;https://i.stack.imgur.com/p00ad.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Not sure about you guys but I often test my gatling guns with my multi-meter...)&#xA;&lt;a href=&quot;http://www.militaryparitet.com/perevodnie/data/ic_perevodnie/2105&quot; rel=&quot;noreferrer&quot;&gt;image source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-26T13:15:37.700" LastActivityDate="2015-06-26T13:15:37.700" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16316" PostTypeId="1" AcceptedAnswerId="16323" CreationDate="2015-06-26T03:38:10.963" Score="4" ViewCount="2128" Body="&lt;p&gt;I'm trying to simulate the light switch panel of an Airbus A340 with real electronics components for a model in scale (I'm doing the electronics lights with leds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking a look at &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A340-200-300-20140101.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this PDF &lt;em&gt;(page 129)&lt;/em&gt;&lt;/a&gt;, I would imagine that there are several switches for these lights. But when I searched on Google Images, I couldn't find a photo of this panel, only some diagrams of A320. I never saw one that I could identify.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt;&#xA;How is the light switch panel and/or where can I find a picture or diagram?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE 1:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it something like this?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/ltBYB.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE 2:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm seeing that some switches have 2 or more points? For example NAV &amp;amp; LOGO, what means 1 and 2? Off, NAV or both? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what about STROBE-BEACON, what does &quot;AUTO&quot; mean?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, I couldn't find the &quot;CARGO&quot; light, and I think that &quot;DOME&quot; are the Landing Gear Bay, but what does BRT/DIM mean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE 3:&lt;/strong&gt;&lt;br&gt;&#xA;I was reading this: &#xA;&lt;a href=&quot;http://www.google.com.ar/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=7&amp;amp;ved=0CDMQFjAG&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DA340_Flight_Deck_and_Systems_Briefing_For_Pilots.pdf&amp;amp;ei=3VeNVaK8Oovu-AHxhpLwAw&amp;amp;usg=AFQjCNF7CD4wBskJQLZCVGdYbk6TxKCyKw&amp;amp;sig2=PzjMhSJo1iRY-UcFOkgvWA&amp;amp;bvm=bv.96782255,d.cWw&amp;amp;cad=rja&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIRBUS A340 - Flight Deck and System Briefing for Pilots&lt;/a&gt;&#xA;But I couldn't find an image about the navigation panel.&lt;/p&gt;&#xA;" OwnerUserId="8985" LastEditorUserId="2176" LastEditDate="2015-06-29T10:21:37.023" LastActivityDate="2015-06-29T10:21:37.023" Title="How is the lighting panel of an Airbus A340 designed and how does it work?" Tags="&lt;airbus&gt;&lt;cockpit&gt;&lt;aircraft-lighting&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16317" PostTypeId="1" AcceptedAnswerId="16318" CreationDate="2015-06-26T04:00:48.807" Score="12" ViewCount="2518" Body="&lt;p&gt;My first guess is that they would catastrophically fail - but I also read the Eurocopter Cougar has propeller blades that will withstand the impact of a 20mm round (I'm guessing other military helicopters are similar).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it likely that the probe could bounce off or is it a pretty much guaranteed byebye scenario? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also could the rotor become entangled in the hose or would it simply slice it?&lt;/p&gt;&#xA;" OwnerUserId="9073" LastActivityDate="2015-06-26T04:19:08.497" Title="What would happen if a helicopters rotor hit the [in-air] refueling probe?" Tags="&lt;military&gt;&lt;helicopter&gt;&lt;refueling&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16318" PostTypeId="2" ParentId="16317" CreationDate="2015-06-26T04:18:03.543" Score="19" Body="&lt;p&gt;It would chop it &lt;a href=&quot;https://www.youtube.com/watch?v=VAdpKpppZiA&quot;&gt;right off&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Watch the video. It's fun. When the helicopter pitches up right after refueling, the rotor disc cannot follow the movement (its hinges allow the blades to pitch up and down, and inertia makes it change its plane of rotation only slowly). The refueling probe is cut cleanly in half.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I would not try this on purpose. The risk of damaging a blade is considerable. I am sure the rotor blades needed to be replaced after that incident.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-06-26T04:18:03.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16319" PostTypeId="2" ParentId="16317" CreationDate="2015-06-26T04:19:08.497" Score="6" Body="&lt;p&gt;Apparently it snips the probe off. No report of wether the rotor was damaged, the probe may have been built with this in mind, and thus out of weaker materials than the rotor blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=VAdpKpppZiA&quot;&gt;https://www.youtube.com/watch?v=VAdpKpppZiA&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-06-26T04:19:08.497" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16320" PostTypeId="1" AcceptedAnswerId="16328" CreationDate="2015-06-26T04:30:24.577" Score="41" ViewCount="17928" Body="&lt;p&gt;The &lt;a href=&quot;http://www.space.com/16666-sr-71-blackbird.html&quot;&gt;SR-71 Blackbird&lt;/a&gt; is a famous supersonic reconnaissance/spy aircraft, undoubtedly one of the most amazing flying machines ever. Now, with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Specifications_.28SR-71A.29&quot;&gt;capabilities&lt;/a&gt; it had: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Maximum speed: Mach 3.3 (2,200+ mph, 3,540+ km/h, 1,910+ knots) at&#xA;  80,000 ft (24,000 m)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How was it used for spying? It must have been difficult to focus on any object on the ground, from such a great height and then many problems are encountered with high speed photography. How were these and many other problems overcome?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-06-26T13:38:24.387" LastActivityDate="2017-10-02T02:51:03.493" Title="How did SR-71 spy, flying at 80,000 ft and 3500 km/h?" Tags="&lt;aviation-history&gt;&lt;sr-71&gt;&lt;reconnaissance-aircraft&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="16321" PostTypeId="1" AcceptedAnswerId="16322" CreationDate="2015-06-26T04:42:57.130" Score="4" ViewCount="332" Body="&lt;p&gt;A car boasting 700HP and under the U.S LSA weight limit was just announced by &lt;a href=&quot;http://www.divergentmicrofactories.com/&quot; rel=&quot;nofollow&quot;&gt;Divergent Technologies&lt;/a&gt;. I was curious on peoples thoughts on using this technique in planes. Obviously there are some issues with the surface of the structure bearing load, but I imagine these could be overcome.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="1696" LastEditDate="2016-07-08T19:53:59.720" LastActivityDate="2016-07-08T19:54:13.847" Title="Would it be possible to use 3D printed node based structures to make cheaper GA planes?" Tags="&lt;aircraft-design&gt;&lt;general-aviation&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16322" PostTypeId="2" ParentId="16321" CreationDate="2015-06-26T06:23:15.460" Score="6" Body="&lt;p&gt;3D printing is unlikely to make anything cheaper in the near future. With current printing technologies it's an order or magnitude or two more expensive per unit than volume manufacturing techniques such as extrusion or injection moulding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's notable that the company you link to chose to make a supercar rather than a low-cost small car. There's little price competition in that market, as brand loyalty dominates. Most supercars are bought as status symbols or for fun rather than for their actual road performance. Most of the incumbents manufacture very small runs with a lot of hand assembly: exactly the kind of manufacturing that 3D printing is competitive for. On top of that, because of the status symbol marketing, there's huge room for new players to differentiate based on a green image. Tesla has done this in the last few years, which is why some of DMF's marketing material focuses on dissing electric cars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runs are small in GA too, so there's potentially a wider niche for these techniques to fit into. The market that would most closely fit IMO is kit aircraft. A kit that's primarily 3D printed parts joined by standard spars, with a flexible outer shell, could have shorter lead times and less tooling cost.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;After discussing this with some mechanical engineer colleagues today, they pointed out how 3D printing of metals is now being used as a complement to CNC machining in the rocket industry. For a part that has to be machined from a single piece of metal, they 3D print a shell that's slightly larger than the required shape, and then machine it to the correct shape. It allows you to achieve the tolerances you get from machining (which 3D printing can't yet deliver), but without the waste you get from cutting down a solid block.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's an aside to the main question, but it's a way that 3D printing could be used to reduce the cost of some components and allow designs that would have been economically infeasible.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-06-27T07:25:19.980" LastActivityDate="2015-06-27T07:25:19.980" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16323" PostTypeId="2" ParentId="16316" CreationDate="2015-06-26T07:12:17.503" Score="6" Body="&lt;p&gt;Nav and logo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The logo light is a spotlight which illuminates the tail to show the airlines logo at night.  The Airbus A340 has two circuits for NAV/LOGO. Logo is an auto option when the landing gear is not compressed or the flaps are extended at 15º or more.&quot; in both positions, 1 and 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dome is the cockpit ambient lighting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strobe on means the strobe is lit.  Auto means that the strobe is on when the landing gear is not compressed - i.e. it comes on just at the point of take-off and switches off on landing.  The point of having &quot;on&quot; as well is that some procedures require the strobe to be turned on just before entering the active runway and when leaving it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of the panel:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/VU27n.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-06-27T07:04:32.527" LastActivityDate="2015-06-27T07:04:32.527" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16324" PostTypeId="2" ParentId="16321" CreationDate="2015-06-26T07:26:54.340" Score="3" Body="&lt;p&gt;3D printing is still an emerging technology. It's far from practical as a primary manufacturing method, but it is certainly possible as parts production - it is vastly cheaper to maintain a database of instructions than a warehouse of parts. Printers capable of making 1000cm$^3$ parts out of structural plastics like ABS are readily available on Amazon for $600. If you need bigger, the price goes up. A lot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus at one point was experimenting with 3D printing of sintered metals. If that ever works out it will revolutionise the spare parts industry, probably not in a good way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Dan said, kit and model aircraft will be early adopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://xkcd.com/924/&quot; rel=&quot;nofollow&quot;&gt;Obligatory xkcd&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1632" LastEditorUserId="1696" LastEditDate="2016-07-08T19:54:13.847" LastActivityDate="2016-07-08T19:54:13.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16328" PostTypeId="2" ParentId="16320" CreationDate="2015-06-26T08:36:36.600" Score="63" Body="&lt;p&gt;The SR-71 Blackbird was equipped with specialized cameras. It would overfly the area of interest and take high-resolution pictures of the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of particular interest is the Technical Objective Camera (TEOC). It could shoot pictures with a 6'' resolution from the operational altitude of the SR-71. This task was not simple as the aircraft would have moved several hundred feet forwards during the exposure time of the picture which was (depending on the settings) around one or two tenths of a second. Without some kind of correction, this would have resulted in a picture that was blurry in the direction of motion of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To solve this, the velocity over height ratio number was fed to the camera, either manually as computed by the pilot or automatically as computed by the sensors and computer of the SR-71 (and it turns out that the machine did a better job at this than the pilot) and while the picture was taken, the high-precision mirror that directed the camera FOV downwards would rotate in the opposite direction towards which the airplane was moving, thus cancelling it out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DBxya.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="8482" LastEditDate="2015-06-26T13:26:50.650" LastActivityDate="2015-06-26T13:26:50.650" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16329" PostTypeId="1" CreationDate="2015-06-26T10:12:28.183" Score="4" ViewCount="469" Body="&lt;p&gt;You can tracks &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;nofollow&quot;&gt;planes&lt;/a&gt;, &lt;a href=&quot;http://www.waze.com&quot; rel=&quot;nofollow&quot;&gt;automobiles&lt;/a&gt; and &lt;a href=&quot;https://www.vesselfinder.com/nl&quot; rel=&quot;nofollow&quot;&gt;boats&lt;/a&gt; on Internet, but does tracking technology exist for drones and if so, can you follow them online?&lt;/p&gt;&#xA;" OwnerUserId="4163" LastEditorUserId="572" LastEditDate="2015-06-26T17:13:37.957" LastActivityDate="2017-09-26T11:39:02.253" Title="Can you track drones online?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;online-tracking&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16330" PostTypeId="2" ParentId="16329" CreationDate="2015-06-26T11:16:06.667" Score="2" Body="&lt;p&gt;As far as the tracking on aviation websites goes, no you cannot, at least not with the drones or UAVs available for leisure activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to track these devices they would either need to be equipped with FLARM or a transponder with Mode-S, which again would require a registration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless you have fitted a GPS transceiver to your UAV which offers online tracking via the vendor's website, you will be unable to track UAVs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related:&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/10049/572&quot;&gt;How do you track and visualize aircraft from home?&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/13335/572&quot;&gt;Why do helicopters not appear in flight trackers?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-06-26T11:25:13.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16331" PostTypeId="1" CreationDate="2015-06-26T11:33:31.750" Score="12" ViewCount="1198" Body="&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=488282db&amp;amp;opt=2048&quot;&gt;In this event&lt;/a&gt;, the crew of a 777 responded to a spurious cargo fire indication by activating the fire suppression system, which suffocates the cargo area. Presumably any pets held there would have died as a result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the SOPs for fire suppression when carrying pets in the cargo hold? Are they held in a separate compartment?&lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="19" LastEditDate="2016-07-04T12:16:41.653" LastActivityDate="2018-04-21T15:37:58.917" Title="Is the life of pets considered when dealing with a cargo fire indication?" Tags="&lt;cargo&gt;&lt;fire&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16332" PostTypeId="2" ParentId="1753" CreationDate="2015-06-26T12:55:21.983" Score="-3" Body="&lt;p&gt;The weight of the bird radar would be trivial and it could easily fit in the nose cone; they aren't that big.  They don't have to look nearly as far out as weather radar,  All they have to do is indicate altitude and direction.  Aircraft can easily avoid collision by changing altitude.  They only have to miss the bird by being a few feet higher or lower, and birds oftentimes fly level at the same altitude, especially when migrating.  The computer could be programmed to avoid collision by adjusting the angle of ascent or descent.&lt;/p&gt;&#xA;" OwnerUserId="9079" LastActivityDate="2015-06-26T12:55:21.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16333" PostTypeId="2" ParentId="16320" CreationDate="2015-06-26T13:31:02.627" Score="29" Body="&lt;p&gt;This is the section of the original &lt;a href=&quot;http://www.sr-71.org/blackbird/manual/4/4-93.php&quot; rel=&quot;noreferrer&quot;&gt;SR-71 operation manual&lt;/a&gt; that describes in detail how the camera works. The plane was equipped with an Optical Bar Camera &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The Optical Bar Camera (OBC) is a high resolution panoramic camera&#xA;  with a &quot;folded&quot; ----------- lens system. It provides continuous&#xA;  ------- or --------- coverage along the flight track through an angle of 70 degrees on each side of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note: the ----- are blacked out sections in the manual. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manual goes on to talk about the operations of the camera and also notes that it takes 5 inch film with is way bigger (and subsequently higher &quot;resolution&quot;) than the 35mm you would use in a home camera. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the actual cameras. The left is the &lt;a href=&quot;https://www.youtube.com/watch?v=PdOrHE32Kqs&quot; rel=&quot;noreferrer&quot;&gt;Technical Objective Camera&lt;/a&gt; and the right is the Optical Bar Camera. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/u7YGk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;a href=&quot;http://www.wvi.com/~sr71webmaster/sr_sensors_pg1.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The resolution of the TEOC was pretty great &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Programmable system with a 48 inch focal length. The TEOC resolution&#xA;  was 110 lines per millimeter, which equates to about 6&quot; ground&#xA;  resolution from an operational altitude. The TEOC's were mounted both&#xA;  sides of &lt;a href=&quot;https://en.wikipedia.org/wiki/Chine_%28aeronautics%29&quot; rel=&quot;noreferrer&quot;&gt;Chine&lt;/a&gt; controlled by a computer&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/myG5o.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The OBC seems like it may have been more size than resolution &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The OBC could photograph 100,000 square miles of the Earth's surface&#xA;  per hour. Film image 72 miles wide, &amp;amp; film length 10,500ft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MOXd7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And of course you cant have a fancy plane with out lots of buttons and knobs. The control systems for the cameras looked like this&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vDOqT.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth it seems that both of these cameras were really high tech &lt;a href=&quot;https://en.wikipedia.org/wiki/Panning_(camera)&quot; rel=&quot;noreferrer&quot;&gt;panning control&lt;/a&gt; systems for cameras. They are very similar to &lt;a href=&quot;https://en.wikipedia.org/wiki/Equatorial_mount&quot; rel=&quot;noreferrer&quot;&gt;Equatorial Mount&lt;/a&gt; cameras which are used to photograph stars (since the earth is moving), it's also called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Barn_door_tracker&quot; rel=&quot;noreferrer&quot;&gt;barn door tracker&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.wvi.com/~sr71webmaster/sr_sensors_pg1.htm&quot; rel=&quot;noreferrer&quot;&gt;image source, all images&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="354" LastEditDate="2015-06-29T09:16:35.790" LastActivityDate="2015-06-29T09:16:35.790" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16334" PostTypeId="1" AcceptedAnswerId="16336" CreationDate="2015-06-26T13:38:46.817" Score="15" ViewCount="10283" Body="&lt;p&gt;When I'm driving my car, I almost always put some music on. It's really relaxing for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that piloting a plane is nothing like driving a car, but it would be great, at least for me, to listen to some music while piloting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here is my question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it allowed to listen to music while piloting a plane? Maybe with some device that mutes the music when someone is speaking in the radio? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastActivityDate="2019-02-13T23:41:54.303" Title="Is it allowed to listen to music while piloting a plane?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16336" PostTypeId="2" ParentId="16334" CreationDate="2015-06-26T13:45:58.000" Score="21" Body="&lt;p&gt;Many aviation headsets either have an Aux-jack or a bluetooth connection, and listening to music is specifically mentioned as a feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.sportys.com/pilotshop/bose-a20-aviation-headset-with-bluetooth.html&quot; rel=&quot;noreferrer&quot;&gt;Link to headset&lt;/a&gt;)&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/10335&quot; rel=&quot;noreferrer&quot;&gt;Link to adapter&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some headsets even have a feature that detects radio-communications, and immediately silences the music.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has no problem with pilots listening to music provided its not distracting.   Individual company policies may differ.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2018-07-22T21:41:29.650" LastActivityDate="2018-07-22T21:41:29.650" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16338" PostTypeId="5" CreationDate="2015-06-26T17:16:18.997" Score="0" Body="" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-06-26T17:16:18.997" LastActivityDate="2015-06-26T17:16:18.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16339" PostTypeId="4" CreationDate="2015-06-26T17:16:18.997" Score="0" Body="online-tracking refers to visually displaying the position of aircraft on a map in order to track the movement over time. The question is aimed at seeking information about how aircraft are tracked, how the data is processed or how it is displayed." OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-06-26T17:16:18.997" LastActivityDate="2015-06-26T17:16:18.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16340" PostTypeId="2" ParentId="16321" CreationDate="2015-06-26T18:08:42.580" Score="1" Body="&lt;p&gt;The comments here are on point however I would like to mention that its very actively being looked into. &lt;a href=&quot;http://www.computerworld.com/article/2921583/3d-printing/ge-3d-prints-a-working-rc-jet-engine.html&quot; rel=&quot;nofollow&quot;&gt;GE successfully 3D printed a full working mini jet engine&lt;/a&gt;. That in and of its self is a pretty cool accomplishment. However it should be noted that the cost may not have been fully considered for that particular project.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;GE also has at least one &lt;a href=&quot;http://www.gereports.com/post/116402870270/the-faa-cleared-the-first-3d-printed-part-to-fly&quot; rel=&quot;nofollow&quot;&gt;FAA cleared part that is 3D printed&lt;/a&gt;. It is a part for the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow&quot;&gt;GE90-94B jet engine&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-26T18:08:42.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16341" PostTypeId="2" ParentId="16316" CreationDate="2015-06-26T18:11:48.097" Score="6" Body="&lt;p&gt;I found it, specifically for A340, page 11 of this document:&#xA;&lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/FCOM_A340-Lights.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.smartcockpit.com/aircraft-ressources/FCOM_A340-Lights.html&lt;/a&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/YbOII.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wOy4D.png&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zfYJt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8985" LastEditorUserId="8985" LastEditDate="2015-06-26T18:46:32.800" LastActivityDate="2015-06-26T18:46:32.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16342" PostTypeId="1" AcceptedAnswerId="16361" CreationDate="2015-06-26T20:23:51.223" Score="3" ViewCount="447" Body="&lt;p&gt;I was trying flightgear simulator since I am not a pilot (but have completed ground school) and one thing I have noticed is that the P-Factor increases with thrust applied whether taking off or in cruise flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this realistic? Does P-Factor vary based on thrust?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-06-27T13:13:16.137" Title="Does P-Factor increase with thrust?" Tags="&lt;general-aviation&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16343" PostTypeId="2" ParentId="16329" CreationDate="2015-06-26T21:39:15.537" Score="0" Body="&lt;p&gt;Technically it is possible to track large UAVs as well, if they have transponders they would show up like civil aircraft, as in radar trackers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they do not have regular ATC transponders, &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;nofollow&quot;&gt;the ADS-B system&lt;/a&gt;, which is used for traffic collision avoidance, will give out UAV flight data, which potentially could be published online by anyone with the necessary receiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, small UAVs (smaller than 10kg, let's say) would probably not carry the above mentioned transponders, so possibly their ground control stations sohuld submit flight data to a central server, to allow people following drone flights.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-06-26T21:39:15.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16344" PostTypeId="2" ParentId="11178" CreationDate="2015-06-26T22:33:46.660" Score="26" Body="&lt;p&gt;The question was formulated in the context of a jet liner such as the Boeing 737-800 or the Airbus, I do not understand why there are persons responding to this question in the context of a smaller less complex aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that being said, I will like to expand the answer by DeltaLima. Boeing uses a device attached to the Brake Metering Valve Module called a De-spin Actuator. This device directs controlled hydraulic fluid to the brakes when the landing gear lever is set to retract to stop the spinning of the wheels. More information can be found in the AMM ATA 32 (Aircraft Maintenance Manual Chapter on Landing Gear).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/aviationisawesome/videos/1598830786833154/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.facebook.com/aviationisawesome/videos/1598830786833154/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Video of a 737-500 from inside the main gear wheel well shows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;After becoming airborne, the landing gear suspension unloads and the wheel hangs down, still spinning&lt;/li&gt;&#xA;&lt;li&gt;Once the main gear arms begin retracting, the wheel stops within a second&lt;/li&gt;&#xA;&lt;li&gt;The gear has fulled retracted in 6-7 seconds.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DuaG9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;De-Spin Actuator&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.eaton.com/ecm/groups/public/@pub/@eaton/@aero/documents/content/ct_194202.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.eaton.com/ecm/groups/public/@pub/@eaton/@aero/documents/content/ct_194202.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9088" LastEditorUserId="34744" LastEditDate="2019-08-16T14:17:52.873" LastActivityDate="2019-08-16T14:17:52.873" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="16345" PostTypeId="1" AcceptedAnswerId="16347" CreationDate="2015-06-26T22:55:21.843" Score="2" ViewCount="218" Body="&lt;p&gt;I recently watched a YouTube video titled &quot;&lt;a href=&quot;https://youtu.be/bMUdXJPUwm8&quot; rel=&quot;nofollow&quot;&gt;Dangerous Crosswind Landings during a Storm at Düsseldorftitled&lt;/a&gt;&quot; and witnessed at the &lt;a href=&quot;https://youtu.be/bMUdXJPUwm8?t=1m54s&quot; rel=&quot;nofollow&quot;&gt;2:06 mark&lt;/a&gt;, a twin engine commercial jet aircraft landing and noticed only one thrust reverser was deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for a knowledgeable answer, asking if this was a malfunction.  &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="19" LastEditDate="2017-01-25T14:10:26.913" LastActivityDate="2017-01-25T14:10:26.913" Title="Can thrust reversers possibly collapse due to strong crosswinds?" Tags="&lt;landing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16346" PostTypeId="1" CreationDate="2015-06-26T23:30:35.933" Score="3" ViewCount="215" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/Pilot-Resources/Safety-and-Proficiency/Accident-Analysis/Nall-Report/Nall_23_R4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nall report&lt;/a&gt; and as voretaq7 explained &lt;a href=&quot;https://aviation.stackexchange.com/a/8294/8389&quot;&gt;here&lt;/a&gt;, around 11% of fatalities in general aviation are due to mechanical failure and maintenance issues.  Although these numbers are relatively small (about 25 per year) they are a danger that even a very cautious pilot would seem to have little control over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So, if annual inspections were performed twice a year, does the data suggest  it would impact these numbers significantly?&lt;/strong&gt;  Please include references to studies and their implications.&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="8389" LastEditDate="2017-08-25T17:53:50.290" LastActivityDate="2017-08-25T17:53:50.290" Title="Is it safer to have an airplane inspected twice a year?" Tags="&lt;safety&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-06-27T09:47:40.590" ContentLicense="CC BY-SA 3.0" />
  <row Id="16347" PostTypeId="2" ParentId="16345" CreationDate="2015-06-26T23:40:53.277" Score="4" Body="&lt;p&gt;It is impossible to tell from the video what the reason or cause was, this is all speculation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most likely it was a malfunction of the thrust reverser. There is a good change that the crew was aware of the problem before take-off; the Airbus A330 may be dispatched with one or even both thrust reversers unserviceable according to the minimum equipment list (MEL)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility is that the crew accidentally only activated one thrust reverser. Given the firm landing (as it should be given the strong crosswind) they might have erred in the heat of the moment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is unlikely that the decision to use only one reverser was on purpose if two reverser were serviceable. On the ground the aircraft has a tendency to weathercock into the wind because of the vertical tail. Selecting only the windward thrust reverser aggravates that tendency. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-26T23:40:53.277" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16348" PostTypeId="2" ParentId="16321" CreationDate="2015-06-26T23:54:06.933" Score="2" Body="&lt;p&gt;I work at a company that routinely uses 3D printers for design of new components - although not for the aviation industry.  As the other posters have said, these parts are not cheaper than parts produced using other technologies.  However, &lt;strong&gt;our 3D printers have vastly increased the efficiency (and decreased cost) at which we can design new products.&lt;/strong&gt;  Although 3D modeling of new parts in software goes a long way, being able to actually use the part in a prototype is a complete game changer.  And by printing out modified designs we can dramatically shorten the feedback loop to arrive at the &quot;right&quot; design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would suspect that use of this technology by aircraft manufactuers could therefore decrease the cost of design which might result in decreased costs overall.&lt;/p&gt;&#xA;" OwnerUserId="8389" LastActivityDate="2015-06-26T23:54:06.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16349" PostTypeId="1" AcceptedAnswerId="16352" CreationDate="2015-06-27T00:39:15.403" Score="10" ViewCount="1873" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow&quot;&gt;vertical take-off and landing (VTOL)&lt;/a&gt; aircraft is one that can hover, take off, and land vertically. We have several military fighter jets, which can takeoff and land vertically (like the &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB4QFjAA&amp;amp;url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FHarrier_Jump_Jet&amp;amp;ei=yfCNVeiABYK5uATCpZbQCQ&amp;amp;usg=AFQjCNEcVDkDYsY8R-iKcyFt3rjKyJnpvg&amp;amp;sig2=FrAWGUklPuxSAorRyUSlMg&quot; rel=&quot;nofollow&quot;&gt;Harrier Jump Jet&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be possible to design an airliner (for example as big as a A320 carrying over a hundred people and travelling at 0.85 mach) to perform VTOL?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="65" LastEditDate="2015-06-29T14:18:59.320" LastActivityDate="2017-04-19T07:46:18.123" Title="Can airliners benefit from vertical take-off and landing?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;vtol&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16350" PostTypeId="2" ParentId="16349" CreationDate="2015-06-27T01:54:47.720" Score="11" Body="&lt;p&gt;A big part of making an aircraft that can take off and land vertically is the thrust to weight ratio has to be greater than 1 so that it can work against the force of gravity. The Harrier Jump Jet can only take off vertically when it isn't loaded to full capacity (in which case STOL is used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a commercial airliner to perform VTOL, taking the A320 as an example, it would require more than 765 kN of thrust, which is 3.2 times the thrust it currently has. Such engineering is infeasible with current technology.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320_family#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320&lt;/a&gt; mass is 78 tonnes, so the weight is ~765 kN.&lt;/li&gt;&#xA;&lt;li&gt;The two &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56#CFM56-5B_series&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56-5B4&lt;/a&gt;'s produce 240 kN.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9091" LastEditorUserId="14897" LastEditDate="2017-04-19T07:46:18.123" LastActivityDate="2017-04-19T07:46:18.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16351" PostTypeId="1" CreationDate="2015-06-27T02:31:30.290" Score="10" ViewCount="451" Body="&lt;p&gt;I'm guessing mid-air refueling has constraints on windspeed and wind direction, visibility, and precipitation. I may have missed some, but those alone make me feel like &lt;strong&gt;mid-air refueling can't be done most of the time (?)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;About wind direction though, I guess you could just fly in the &quot;right direction&quot;, but then this would also have constraints because the &quot;right&quot; direction could lead away from your ultimate destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(also, is there a mid-air refueling tag I couldn't find?)&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="7532" LastEditDate="2015-08-01T20:09:31.973" LastActivityDate="2015-08-01T20:09:31.973" Title="Does mid-air refueling have very hard constraints on weather?" Tags="&lt;military&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16352" PostTypeId="2" ParentId="16349" CreationDate="2015-06-27T03:51:48.887" Score="13" Body="&lt;p&gt;The closest to what you ask was maybe the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_31&quot; rel=&quot;noreferrer&quot;&gt;Do-31&lt;/a&gt; experimental VTOL transport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/K8FnG.jpg&quot; alt=&quot;Dornier Do-31 in hover&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dornier Do-31 in hover. Picture &lt;a href=&quot;http://www.diseno-art.com/news_content/2013/10/strange-vehicles-dornier-do-31-vtol-jet-transport/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was developed to fly supplies to VTOL fighter bases. Makes no sense to have a VTOL fighter fleet if you cannot supply them, right? That was what the Do-31 was for, and the technically successful program folded when NATO abandoned the VTOL strategy in the Sixties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to regional airliners of its time, the table below shows how much the installation of sufficient thrust has cut performance:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bTkR3.png&quot; alt=&quot;Performance comparison between Do-31 and F-28&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fokker_F28_Fellowship&quot; rel=&quot;noreferrer&quot;&gt;Fokker F-28&lt;/a&gt; for comparison, because it is of similar size and age. As you can see, VTOL easily costs half the payload. 36 fully equipped troops may weigh more than 36 passengers, but they will sit on much lighter seats and have much more frugal accommodations. Note that I used the reduced take-off mass for VTOL flight, but have no information if that mass would have included the full payload. The range is valid only for the higher maximum take-off mass of 24.5 tons, for which a conventional take-off was necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Do-31 could have fitted the Belgian airline &lt;a href=&quot;https://en.wikipedia.org/wiki/Sabena&quot; rel=&quot;noreferrer&quot;&gt;SABENA&lt;/a&gt;, which at the time (the Fifties and Sixities of the last century) had the most advanced VTOL strategy of all airlines. They operated &lt;a href=&quot;https://www.youtube.com/watch?v=0sC5jXQZEuA&quot; rel=&quot;noreferrer&quot;&gt;regional connections with helicopters&lt;/a&gt;, but eventually reverted to regular aircraft well before the Do-31 would had been available. &lt;a href=&quot;https://en.wikipedia.org/wiki/Heli_Air_Monaco&quot; rel=&quot;noreferrer&quot;&gt;Heli-Air Monaco&lt;/a&gt; is still in operation after almost 40 years, but this is more a taxi service than an airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering not only the increased fuel consumption, but also the increased maintenance cost on more and diverse engines (most VTOL airplanes have dedicated lift engines), the operating cost even at the times of cheap fuel were too high to make the convenience worth it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it is possible to develop a VTOL A320, but it would look very different, would cruise at a lower speed and have a much reduced payload and range. Tickets would be horrendously expensive, though.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: Thanks to @egid for his suggestion to use mass fractions for comparison. Unfortunately, I found &lt;a href=&quot;https://books.google.de/books?id=V1DuJfPov48C&amp;amp;pg=PA582&amp;amp;lpg=PA582&amp;amp;dq=Fokker%20F-28%20empty%20weight&amp;amp;source=bl&amp;amp;ots=PbzAbzPn4Z&amp;amp;sig=Cep-wOrWf0ED54xpQaDmpUpJZeo&amp;amp;hl=de&amp;amp;sa=X&amp;amp;ei=0HmPVf3BGIPiU5KPruAD&amp;amp;ved=0CFYQ6AEwBw#v=onepage&amp;amp;q=Fokker%20F-28%20empty%20weight&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;detailed mass data&lt;/a&gt; of the F-28 only for a later version, but the expanded table shows the point clearly:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9aIXi.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The useful load fraction is the result of dividing the difference between take-off mass and operating mass empty by the take-off mass, showing the sum of payload and fuel as a fraction of take-off mass. Adding lift engines, slow-speed controls and a rear loading ramp clearly reduced what could be carried in VTOL flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-28T04:49:51.500" LastActivityDate="2015-06-28T04:49:51.500" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16353" PostTypeId="1" CreationDate="2015-06-27T05:24:09.467" Score="1" ViewCount="196" Body="&lt;p&gt;I'm not sure how to describe this, but the problem came about as I was computing some acceleration profiles. Let's say you want to get up to Mach 3 (939 m/s) quickly. If you accelerate at 3 g's, this will take &lt;strong&gt;31.923 seconds&lt;/strong&gt; (not bad), and in level flight would cover a ground path of &lt;strong&gt;14.991 km&lt;/strong&gt; (kind of a lot, but not really comparable to typical flight lengths).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only problem is, when it comes time to land, you have to slow down. If you want to do that quickly too, well, 3 g's in the &quot;eyeballs-out&quot; direction is a little hard on the eyeballs. Doing 1 g would take 3 times longer but also cover a ground path &lt;strong&gt;more than three times longer&lt;/strong&gt; because of that pesky time squared in the equation for uniform acceleration ($\Delta x = \frac12 at^2$, if initial x and inital v are zero).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you could gradually slow down &lt;strong&gt;over an even longer distance&lt;/strong&gt;, or...is there some other, quicker way that doesn't involve much eyeballs out? Could you maybe fly a circle over the airport and decelerate that way, so that you feel the g-force mostly pointing down into your seat? Is there some other way you could &quot;cut into another plane&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The goal is to decelerate quickly so that the average flight speed (over the whole journey) is very close to Mach 3.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2015-06-27T07:35:30.917" Title="Is there a way to **decelerate** significantly without an &quot;eyeballs-out&quot; sensation?" Tags="&lt;flight-planning&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2015-06-27T09:15:28.607" ContentLicense="CC BY-SA 3.0" />
  <row Id="16354" PostTypeId="2" ParentId="16351" CreationDate="2015-06-27T06:14:02.383" Score="8" Body="&lt;p&gt;The receiver has to have visual contact with the tanker to complete the rejoin, so finding a clear block of airspace (i.e. not IMC) is necessary. Beyond that, none of the factors mentioned really matter much.  Turbulence can make refueling more difficult, although it's often possible to find an altitude with a decent ride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mostly, AR can be done; the times when it can't are much more the exception.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-27T06:14:02.383" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16355" PostTypeId="1" CreationDate="2015-06-27T06:41:49.327" Score="3" ViewCount="356" Body="&lt;p&gt;I flew yesterday in a SWA Boeing 737-300(?) in the seat next to the engine. Right after touchdown, I noticed that part of the cowl retracted back significantly (a few feet or so it seemed), exposing the engine body. The cowl closed back when the speed dropped to taxi levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this cowl retraction for? Is it part of the aerobraking?&lt;/p&gt;&#xA;" OwnerUserId="9092" LastEditorUserId="595" LastEditDate="2015-06-27T07:11:13.237" LastActivityDate="2015-06-27T07:11:13.237" Title="What is the purpose of a retracting cowl?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-06-27T09:15:38.837" ContentLicense="CC BY-SA 3.0" />
  <row Id="16356" PostTypeId="2" ParentId="16355" CreationDate="2015-06-27T06:55:03.663" Score="4" Body="&lt;p&gt;You have seen one type of the possible thrust reversal systems in action. In the following image is the bottom one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YN0pp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;https://engineering.purdue.edu/~propulsi/propulsion/jets/basics/bigpic/thrustreverse1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt; &lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They deploy surfaces that deflect the bypass air and aid the brakes in slowing down the aircraft after touchdown.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-06-27T06:55:03.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16357" PostTypeId="2" ParentId="16353" CreationDate="2015-06-27T07:35:30.917" Score="4" Body="&lt;p&gt;If you need to have an average speed of Mach 3, then cruise at a speed higher than Mach 3 and land at Mach 0.2. And decelerate at a comfortable rate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or fly in a cryogenic wind tunnel to get the speed of sound down so much that Mach 3 is actual a very low speed. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-06-27T07:35:30.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16358" PostTypeId="1" AcceptedAnswerId="16359" CreationDate="2015-06-27T08:54:15.910" Score="3" ViewCount="2265" Body="&lt;p&gt;The impossibly bad 2005 film &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Stealth_(film)&quot; rel=&quot;nofollow&quot;&gt;Stealth&lt;/a&gt;&lt;/em&gt; featured a dirigible-based, mid-air refueling tanker station for the stealth fighters to use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first, this seemed like it might have been the singular good idea in the film as a dirigible would have a very long loiter time making it ideal for fighter refueling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I don't think it's possible, right? What is the maximum known air speed of a dirigible vs. the lowest possible air speed for a tactical fighter? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note: I do think it'd be possible for helicopters and osprey to use a dirigible tanker, right, as their stall speeds can be essentially zero?)&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="1696" LastEditDate="2018-04-19T14:36:18.033" LastActivityDate="2021-01-08T12:56:06.107" Title="Would it be feasible to develop a dirigible-based refueling station for fighter aircraft?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;refueling&gt;&lt;airship&gt;" AnswerCount="5" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16359" PostTypeId="2" ParentId="16358" CreationDate="2015-06-27T09:16:58.037" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What is the maximum known air speed of a dirigible vs. the lowest possible air speed for a [stealth] fighter?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Airship fastest speeds&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.guinnessworldrecords.com/world-records/fastest-speed-for-an-airship&quot; rel=&quot;nofollow&quot;&gt;Guinness&lt;/a&gt; the world record speed for an airship was 70 mph by Steve Fosset in 2004.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Guinness also say &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The large rigid airships built by the USA and Germany in the 1920s and 30s could reach higher speeds (up to 140 km/h or 87 mph according to some sources), but these were never officially measured to FAI standards.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Stealth aircraft slowest speeds&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The F-117 has a landing speed of 180 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35B is stealthy and can hover.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-29T09:36:17.807" LastActivityDate="2015-06-29T09:36:17.807" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16360" PostTypeId="2" ParentId="16321" CreationDate="2015-06-27T11:54:35.550" Score="1" Body="&lt;p&gt;The only kind of 3D printing process which produces structures fit for the load/weight ratios usual in aviation is electron beam printing. It uses titanium, stainless steel or aluminium grains (feels and looks much like sand) and heats that up locally to the melting point in an inert atmosphere, layer by layer. The advantages are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Very fine structure, better than what is achievable by casting.&lt;/li&gt;&#xA;&lt;li&gt;No molds.&lt;/li&gt;&#xA;&lt;li&gt;Geometries which would be impossible to mold by casting or milling.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But there are disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rough surface; minimum roughness is given by grain size.&lt;/li&gt;&#xA;&lt;li&gt;The surface imperfections translate into a notching effect, so the actually usable cross section is smaller than what is produced, which reduces material efficiency.&lt;/li&gt;&#xA;&lt;li&gt;Manufacturing cost hardly goes down with the number of parts.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only areas where this has been used gainfully so far are special cases:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Titanium implants, where replacements for bone structures can be custom-made within less than 24 hours. The rough surface is an advantage here, because it allows better integration into the body.&lt;/li&gt;&#xA;&lt;li&gt;Replacement parts in case a &lt;a href=&quot;https://en.wikipedia.org/wiki/Just-in-Time_Manufacturing&quot; rel=&quot;nofollow&quot;&gt;JIT assembly line&lt;/a&gt; is compromised by one part missing.&lt;/li&gt;&#xA;&lt;li&gt;Impossible geometries like hollow core pins for injection molding. The channels for the cooling water inside can have a corkscrew shape, one for the inflow, and one interleaved for the outflow. The gains in process efficiency can be immense.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, a 3D printed airplane is possible. Cost savings can be realized for a few special parts, but the general structure would certainly be more expensive. Consider that the surface roughness means that at least aerodynamic surfaces and contact areas with other parts need to be planed (e.g. by milling) after 3D printing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While a single-issue sports car might be cheaper to produce this way, I very much doubt that GA manufacturing will benefit from 3D printing soon, even with the reduced production volume of today, except for some special parts.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-27T18:08:45.883" LastActivityDate="2015-06-27T18:08:45.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16361" PostTypeId="2" ParentId="16342" CreationDate="2015-06-27T12:24:15.140" Score="4" Body="&lt;p&gt;Yes, it should. In the end, &lt;a href=&quot;https://aviation.stackexchange.com/questions/312/whats-p-factor-and-why-does-it-occur&quot;&gt;p-factor&lt;/a&gt; is just a funny word for the out-of-center shift of the thrust vector, and if the vector is larger, the effect should be equally larger.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-06-27T12:24:15.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16362" PostTypeId="2" ParentId="16342" CreationDate="2015-06-27T13:13:16.137" Score="2" Body="&lt;p&gt;YES! In fact P -Factor is the asymmetric thrust that the propellers generate at increased AoA(Angles Of Attack). In other words P-factor is the asymmetric disk loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=nBX81yLb9I0&quot; rel=&quot;nofollow&quot;&gt;Thrust and P-factor&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the majority of single engine aircraft, this  means that the aircraft will yaw to the left at high angles of attack unless an appropriate right rudder alteration is applied.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2015-06-27T13:13:16.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16363" PostTypeId="1" AcceptedAnswerId="16374" CreationDate="2015-06-27T13:30:09.353" Score="9" ViewCount="2325" Body="&lt;p&gt;It seems odd that airliners do not have an easy way to monitor critical components on the exterior of the aircraft, should for example, a bird or something else strikes hard enough to cause damage. A mirror or camera would allow a pilot to see and react to a possible dangerous situation quickly. Also, a camera helps a pilot to see what's behind.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="3386" LastEditDate="2015-06-28T14:01:33.467" LastActivityDate="2015-06-28T21:54:19.530" Title="Why don't airliners have any mirrors or cameras?" Tags="&lt;aircraft-limitations&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-06-29T17:44:05.933" ContentLicense="CC BY-SA 3.0" />
  <row Id="16365" PostTypeId="1" CreationDate="2015-06-27T14:43:21.930" Score="26" ViewCount="5943" Body="&lt;p&gt;An anti air missile has often very small wings but out performs a fighter aircraft, e.g. much higher g-load, since g-load comes from lift which is the area of wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not designing an aircraft like a missile? E.g. low drag, high agility.&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="3587" LastEditDate="2015-06-28T00:48:22.987" LastActivityDate="2015-06-30T03:44:36.933" Title="Why does a missile have small wings but better agility than a plane?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16366" PostTypeId="2" ParentId="16365" CreationDate="2015-06-27T15:10:56.613" Score="51" Body="&lt;p&gt;First of all, a missile is operating at a much higher dynamic pressure than the airplane. After all, it has to catch up with it to do its job. Since dynamic pressure scales with the square of airspeed, the wings of a missile twice as fast as the target would need only a quarter of the wing area to produce the same forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, the missile uses its thrust just as much as the lift from its vanes to change direction in the initial flight phase when the rocket motor runs and the biggest course changes are needed. With an airplane, this is normally not possible, since most planes need to fly in a small range of angles of attack and sideslips to operate properly. Exceeding those will produce substantially more drag and might lead to loss of control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, the missile has to carry only the mass for a few seconds of flight. The burning time of a rocket motor is just a few seconds for short-range missiles, and their typical flight time is about 30 seconds. Since they do not need to carry the fuel to return to base, their mass can be held down, which improves agility.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-30T03:44:36.933" LastActivityDate="2015-06-30T03:44:36.933" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16367" PostTypeId="2" ParentId="16358" CreationDate="2015-06-27T18:41:59.973" Score="-4" Body="&lt;p&gt;You mean a dirigible as in lighter-than-air aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it has a long loiter time - it has to get the load up there&lt;br&gt;&#xA;A lighter-than-air aircraft is not designed for a payload   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nitrogen is about 5.4 liters per pound&lt;br&gt;&#xA;Hydrogen is about 0.4 liters per pound&lt;br&gt;&#xA;A 10,000 lb payload is a balloon about 40 meters across &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is once you get it up there and dump 10,000 lbs of fuel you have to get is back to the ground. &#xA;Release a bunch of hydrogen to get it back to the ground is not exactly an ideal situation.  Hydrogen is combustible and not cheap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;10,000 lbs is about one fighter. &#xA;100,000 lbs is about 10 planes and now 80 meters in diameter. &#xA;100 planes (1,000,000 lbs) for like a mid Atlantic fuel station would be 170 meters in diameter. It just does not seem realistic to me. If it is big enough to get the load up there it is less than stealth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost of the hydrogen to float jet fuel cost more than the jet fuel itself.  Hydrogen is fuel and is going to have at a minimum fuel cost.  So robokaren it is produced by (simple) electrolysis of water.  The water is cheap.  The energy to separate the hydrogen is the cost of energy and energy is not cheap. &lt;/p&gt;&#xA;" OwnerUserId="8649" LastEditorUserId="8649" LastEditDate="2015-06-28T13:27:51.777" LastActivityDate="2015-06-28T13:27:51.777" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="16371" PostTypeId="1" CreationDate="2015-06-28T05:35:06.947" Score="12" ViewCount="1012" Body="&lt;p&gt;For instance, on a Cessna 172 what percent is spent on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Raw materials&lt;/li&gt;&#xA;&lt;li&gt;Labor actually manufacturing the plane&lt;/li&gt;&#xA;&lt;li&gt;Testing the completed individual planes&lt;/li&gt;&#xA;&lt;li&gt;R&amp;amp;D Making the plane (at this point, very little for the 172 I suspect&lt;/li&gt;&#xA;&lt;li&gt;Certification testing&lt;/li&gt;&#xA;&lt;li&gt;Insurance&lt;/li&gt;&#xA;&lt;li&gt;Avionics&lt;/li&gt;&#xA;&lt;li&gt;Anything I forgot...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3366" LastEditorUserId="3366" LastEditDate="2015-06-28T19:52:24.397" LastActivityDate="2016-09-07T10:56:25.217" Title="Is there a good source for estimating the per unit cost breakdown for a classic GA plane like the Cessna 172?" Tags="&lt;general-aviation&gt;&lt;cost&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16372" PostTypeId="2" ParentId="15637" CreationDate="2015-06-28T07:41:10.560" Score="8" Body="&lt;p&gt;@DamalaniSingh: I wonder why you see the need for a bounty when web pages such as &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; give a good explanation already. In order to avoid a link-only answer, I will summarize the LEX-related gist here (LEX = leading edge extension).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may know that a delta wing forms a &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_lift&quot; rel=&quot;noreferrer&quot;&gt;powerful vortex&lt;/a&gt; on its suction side at high angle of attack which allows it to work well past angles of attack where conventional wings with less leading edge sweep have stalled. Adding what is in essence a small delta ahead of the main wing will give you the benefit of both: Better L/D and overall more lift at low angle of attack, plus much improved &lt;a href=&quot;https://www.youtube.com/watch?v=P_NSxSyrvYA&quot; rel=&quot;noreferrer&quot;&gt;high-alfa capabilities&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanism is the same as for regular delta wings, but the vortex will do its magic not only on the LEX, but also on most of the wing behind it. First a picture of CFD simulations, taken from the &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;Aerospaceweb&lt;/a&gt; page mentioned above:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pu23e.jpg&quot; alt=&quot;CFD simulation of high alfa flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now proof that the same happens in the real world, again copied from the &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;Aerospaceweb&lt;/a&gt; page:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hwb2F.jpg&quot; alt=&quot;Tufted F-18 seen from behind in high-alfa flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the wool tufts on the LEX and wing: The flow over the wing is really separated, because the tufts point in all directions except backwards. What is also visible is the disadvantage at high angle of attack: The vortex bursts behind the wing, which causes extreme vibrational loads on the tail fins. They needed to be reinforced at their root to extend the structural life of the airframe. Again, also the last picture of this answer is copied from the &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;Aerospaceweb&lt;/a&gt; article. You should read it yourself!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gyUHd.jpg&quot; alt=&quot;F-18 fin reinforcements in close-up&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@VictorJuliet: And lastly, please give the bounty to Pawel! His answer was first, and it is correct. I have enough reputation already.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-28T10:30:40.010" LastActivityDate="2015-06-28T10:30:40.010" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16374" PostTypeId="2" ParentId="16363" CreationDate="2015-06-28T14:15:28.340" Score="8" Body="&lt;p&gt;Aircraft rarely collide with any objects. Cameras would only be helpful if the extent of the damage is visible from the outside. Instruments, on the other hand, can be used to diagnostic the problem even if the system fails &quot;internally&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g. Many hydraulic lines and cables run across the wing. If these is damage on the leading edge, is it the slats? A hydraulic leak on system A? system B? Is the de-ice working? You need instruments to get a better picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft indeed come with cameras. The Boeing 777 has cameras on the bottom of the fuselage and the tail to aid pilots during taxi operations (the 777, especially the 777-300 variant, is &lt;em&gt;really&lt;/em&gt; long...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JT1fX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Airbus A380 also has a tail mounted camera. Passengers can enjoy a spectacular view of the clouds, the high speed takeoffs and landings:&lt;img src=&quot;https://i.stack.imgur.com/7jezZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for mirrors, pilots don't overtake other planes or back off like drivers do. There really is no need to know what is behind the aircraft. Pushback is accomplished by the tug on the ground, who has a much better view of the area than the pilots.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="39" LastEditDate="2015-06-28T21:54:19.530" LastActivityDate="2015-06-28T21:54:19.530" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16376" PostTypeId="1" CreationDate="2015-06-28T17:32:06.147" Score="14" ViewCount="10865" Body="&lt;p&gt;The attitude indicator is very important for any sort of instrument flying, so it must be accurate at all times regardless of the plane's movements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume that the indicator would be connnected to a gyroscope. However, gyroscopes drift, and a drifting attitude indicator would be pretty useless. Of course, you might have a reset button, but safely using it would require a visual reference to a horizon, which obviously you don't have during IFR flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another idea might be to periodically reset the indicator based on gravity --- many model aircraft use this something like this approach to drive an attitude calculation; however, during coordinated turns, the gravity vector is indistinguishable from the vector during level flight. If a plane continually turns in a coordinated way, such an attitude indicator would be confused in exactly the same way that a human would be, resulting in bad things like the autopilot doing a &lt;a href=&quot;https://en.wikipedia.org/wiki/Graveyard_spiral&quot;&gt;graveyard spiral&lt;/a&gt;. A gravity sensor + accelerometer wouldn't be able to detect the difference between a gradual turn into a steeper and steeper coordinated spiral and simply a gradual gyroscope drift while remaining in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are attitude indicators kept from drifting?&lt;/p&gt;&#xA;" OwnerUserId="8357" LastActivityDate="2018-02-20T21:48:04.163" Title="How are attitude indicators kept accurate?" Tags="&lt;flight-instruments&gt;&lt;attitude&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16377" PostTypeId="1" AcceptedAnswerId="16384" CreationDate="2015-06-28T22:48:40.560" Score="29" ViewCount="16226" Body="&lt;p&gt;I've read that the SR-71 had no missile defenses because it could simply &lt;a href=&quot;http://theaviationist.com/2013/12/04/sr-71-speed-enemy/&quot; rel=&quot;noreferrer&quot;&gt;outrun any adversary&lt;/a&gt;. Is this still true? Or is it unlikely that the SR-71 could operate unimpeded in the face of modern technology? &lt;/p&gt;&#xA;" OwnerUserId="9104" LastEditorUserId="3386" LastEditDate="2018-04-22T04:31:58.213" LastActivityDate="2019-03-27T00:51:16.047" Title="Could a SR-71 be shot down today?" Tags="&lt;military&gt;&lt;missiles&gt;&lt;sr-71&gt;&lt;reconnaissance-aircraft&gt;" AnswerCount="7" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16379" PostTypeId="1" CreationDate="2015-06-28T23:14:10.290" Score="4" ViewCount="2180" Body="&lt;p&gt;What are the advantages of using all-moving control surfaces? can someone give explanations based on aerodynamics? &lt;/p&gt;&#xA;" OwnerUserId="9106" LastActivityDate="2015-06-29T20:06:00.650" Title="Why most of the supersonic or fighter aircraft use all-moving control surfaces?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16380" PostTypeId="2" ParentId="16377" CreationDate="2015-06-29T03:02:10.210" Score="5" Body="&lt;p&gt;Certainly yes. This &lt;a href=&quot;http://web.archive.org/web/20150727112346/https://en.wikipedia.org/wiki/List_of_modern_surface-to-air_missiles#Long_Range_.2880km.2B.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; page states several missiles:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/05iVH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/05iVH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These have a greater speed than the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Specifications_.28SR-71A.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;SR-71&lt;/a&gt; and a greater flight ceiling. Aso, if white house decides to turn its own enemy, then it can create a havoc with &lt;a href=&quot;https://en.wikipedia.org/wiki/RIM-161_Standard_Missile_3&quot; rel=&quot;nofollow noreferrer&quot;&gt;SM-3 Block 1B&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="14897" LastEditDate="2019-03-27T00:51:16.047" LastActivityDate="2019-03-27T00:51:16.047" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16381" PostTypeId="1" AcceptedAnswerId="16550" CreationDate="2015-06-29T03:42:28.843" Score="5" ViewCount="26483" Body="&lt;p&gt;I recently developed a sudden interest in flying. I'm wondering whether a pair of small ducted fans could lift a person off the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets say the ducted fan is 15cm in diameter. What would be the most thrust a fan like that could produce?&lt;/p&gt;&#xA;" OwnerUserId="9107" LastEditorUserId="2341" LastEditDate="2015-07-01T12:33:26.833" LastActivityDate="2020-12-07T07:15:33.097" Title="What is the highest possible thrust generated by 15cm ducted fan?" Tags="&lt;lift&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16382" PostTypeId="2" ParentId="16376" CreationDate="2015-06-29T07:31:37.607" Score="2" Body="&lt;p&gt;I've had this same question and even asked my flight instructor. He said the attitude indicator does not drift because it is on a 2-axis gimbal and rotates freely and will not precess or become incorrect unless it tumbles (reaches the physical limits of its movement), such as happens when doing aerobatics. A directional gyro, however, will drift due to the fact that it is only on a 1-axis gimbal and is deflected against when the aircraft accelerates, turns, or maneuvers. I'm still not sure how it is not subject to precession as it is a mechanical system and thus subject to friction and forces, but that's what the CFI said. He looked puzzled by my question (the same one you are asking) and answered as if the attitude indicator is never wrong.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-06-29T07:31:37.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16384" PostTypeId="2" ParentId="16377" CreationDate="2015-06-29T09:33:20.583" Score="35" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Could SR-71 be shot down today?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Theoretically yes. Modern day SAMs like the 40N6 that travel at speeds of Mach 6 can intercept an SR 71 within an operational range of 250 miles upto an altitude of 18 miles. Moreover, the hostile SAM will fire a salvo of missiles(at least 2-3). So the SR 71 will have to jam, drop decoys and out manoeuvre the incoming hostile missiles.Modern day SAM systems can be loaded with libraries of 3D shapes that can be used by the seeker to identify targets and threats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;S-400 and similar Russian/Chinese AD systems are meant to work simultaneously with ECM systems, meaning radars of enemy aircraft will be blinded  as 40N6 and 48N6 missiles zeroes in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the days of the cold war Soviet Air Force pilots were instructed to launch two rounds, a semi-active radar homing missile and a heat seeking missile.In this fashion the SR 71( or any other hostile aircraft) being targeted has a difficult problem as it must jam, decoy and/or out manoeuvre three or four tightly spaced inbound missiles&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said getting in the general vicinity of an intercept is different from an actual intercept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.codeproject.com/Articles/19310/Hitting-a-Moving-Target-The-Missile-Guidance-Syste&quot;&gt;http://www.codeproject.com/Articles/19310/Hitting-a-Moving-Target-The-Missile-Guidance-Syste&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Jane's  &lt;strong&gt;&lt;em&gt;Fighter Combat in the Jet Age&lt;/em&gt;&lt;/strong&gt; : Page 116-117 “&lt;em&gt;SR71 the Ultimate Target&lt;/em&gt;” &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On June 3, 1986 an SR 71 was on a mission over the Barents Sea. Six&#xA;  Mig 31 Foxhounds, vastly superior to the Mig25 Foxbat,performed a&#xA;  coordinated intercept that would have subjected the SR71 to an&#xA;  all-angle AAM attack that even a combination of high-altitude&#xA;  maneuverability and ECM could not have defeated. Fortunately for the&#xA;  American jet, the interception took place over international waters,&#xA;  but the Soviets proved their point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In fact,the SR 71 was retired once the USSR started deploying S 300 SAMs in large numbers.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;I've read that SR-71 had no missile defenses because it could simply outrun any adversary. Is this still true?.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That is not true. The SR 71 did carry a very sophisticated Electronic Counter Measure System(ECM) called the &lt;a href=&quot;https://books.google.co.in/books?id=6svmtOFa1JIC&amp;amp;pg=PA75&amp;amp;lpg=PA75&amp;amp;dq=Surface%20to%20air%20missiles%20%2B%20SR%2071&amp;amp;source=bl&amp;amp;ots=pvEeskU76C&amp;amp;sig=5-NXYlR8Q5lFrxlbhOjRxJjEE3I&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ei=gQ6RVf61G9CFuwTWw79o&amp;amp;ved=0CBwQ6AEwADgK#v=onepage&amp;amp;q=Surface%20to%20air%20missiles%20%2B%20SR%2071&amp;amp;f=false&quot;&gt;Defensive System&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the first MiG 31 Foxhound pilots, Captain Mikhail Myagkiy, who had scrambled with his MiG-31 several times to intercept the US super-fast spy plane, explains in his book how he was able to lock on a Blackbird on Jan. 31, 1986:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The scheme for intercepting the SR-71 was computed down to the last&#xA;  second, and the MiGs had to launch exactly 16 minutes after the&#xA;  initial alert. (…) They alerted us for an intercept at 11.00. They&#xA;  sounded the alarm with a shrill bell and then confirmed it with a&#xA;  loudspeaker. The appearance of an SR-71 was always accompanied by&#xA;  nervousness. Everyone began to talk in frenzied voices, to scurry&#xA;  about, and react to the situation with excessive emotion.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Missiles are faster and can sustain higher G loadings than SR-71.  Assuming that the SR 71 is flying at an altitude of  70,000 ft to 80,000 ft  it only needs to maneuver to out turn the missile, in order to  make the change in intercept geometry fall outside the missile's envelope. However, at extreme altitudes aircraft maneuvers are limited by stall buffet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SR-71 could fly a 7,000+ mile mission and the only segments of which are flown at sub sonic speeds  are the take-off, refueling  and landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sr-71.org/blackbird/&quot;&gt;http://www.sr-71.org/blackbird/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sr-71.org/blackbird/diagrams/index.htm&quot;&gt;http://www.sr-71.org/blackbird/diagrams/index.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sr-71.org/blackbird/diagr...conprofile.htm&quot;&gt;http://www.sr-71.org/blackbird/diagr...conprofile.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing is the Soviets knew that in order for any Soviet fighter aircraft to intercept an SR-71 it had to be ahead of its known flight path. These were the tactics the Soviets deployed to even get a glimpse of the SR-71. They always knew when an SR-71 launch would occur because the KC-135 fuel tanker would take off first because the SR-71 had to be immediately refueled once airborne.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="774" LastEditDate="2015-07-01T03:54:48.200" LastActivityDate="2015-07-01T03:54:48.200" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16387" PostTypeId="1" AcceptedAnswerId="16393" CreationDate="2015-06-29T10:29:55.050" Score="10" ViewCount="1692" Body="&lt;p&gt;Every time I fly in an airplane that has an In-Flight Entertainment System (IFE) that consists of screens embedded in every passenger seat it is only turned on a few minutes after take-off and turned off a few minutes before landing? Why is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My limited knowledge of the system tells me that it should not interfere with any of the other on-board systems and thus it should not matter whether the system is running or not. The only reason I can think of is safety, similar to the question of &lt;a href=&quot;https://aviation.stackexchange.com/questions/8471/why-are-the-lights-inside-commercial-airplanes-turned-off-during-take-off-and-la&quot;&gt;why lights are dimmed during take-off and landing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9112" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2019-03-05T15:10:12.467" Title="Why is the IFE only available after take-off and shut off before landing?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;inflight-entertainment&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16388" PostTypeId="1" CreationDate="2015-06-29T10:36:02.910" Score="9" ViewCount="1352" Body="&lt;p&gt;US has &lt;a href=&quot;http://www.prideaircraft.com/flanker.htm&quot;&gt;bought&lt;/a&gt; or &lt;a href=&quot;http://www.airspacemag.com/military-aviation/truth-about-mig-29-180952403/?no-ist&quot;&gt;sourced&lt;/a&gt; many &lt;a href=&quot;http://english.pravda.ru/world/americas/20-07-2009/108253-su27-0/&quot;&gt;Russian&lt;/a&gt; fighter jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was any Russian design feature incorporated in modern US fighters jets or vice-versa?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="3386" LastEditDate="2018-04-19T17:51:59.490" LastActivityDate="2018-04-21T07:08:21.973" Title="Was any Russian design feature incorporated in modern US fighters jets or vice-versa?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;usa&gt;&lt;fighter&gt;&lt;russia&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16389" PostTypeId="1" AcceptedAnswerId="17385" CreationDate="2015-06-29T12:23:54.550" Score="5" ViewCount="1057" Body="&lt;p&gt;Well, as the question says I am interested in the use of drones in agriculture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any drones designed to carry a tank of some chemical or water?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How large are those tanks?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen that airplanes are used in agriculture and in extinguishing forest fires. They can carry tanks containing 500-2000 kg (or more) of chemicals/water.&lt;/p&gt;&#xA;" OwnerUserId="8414" LastEditorUserId="15982" LastEditDate="2017-02-24T13:59:25.397" LastActivityDate="2017-02-24T13:59:25.397" Title="Are drones used in firefighting, agriculture and pest control?" Tags="&lt;aircraft-design&gt;&lt;unmanned-aerial-vehicle&gt;&lt;fire&gt;&lt;payload&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16390" PostTypeId="2" ParentId="16389" CreationDate="2015-06-29T13:23:25.610" Score="3" Body="&lt;p&gt;I once worked in the UAV company, which was contracted to supply a system to identify trees. To achieve this, all you need is a good camera and an image recognition software (now to be easily written using .NET). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not heard about drones carrying such large amounts of chemicals, so sorry about that. In this part of the world (eastern Europe) we have enough of our own, conventional planes which do the job just fine (like PZL-106 Kruk). I guess buying drones to do that would not be economical (again I'm just speaking for my country)&lt;/p&gt;&#xA;" OwnerUserId="8994" LastActivityDate="2015-06-29T13:23:25.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16392" PostTypeId="1" AcceptedAnswerId="16395" CreationDate="2015-06-29T13:35:50.680" Score="1" ViewCount="1063" Body="&lt;p&gt;In what general situations or flight scenarios is turbulence most dangerous to aircraft? When could it be bad enough to bring down an aircraft (even up to something as big as an A380)?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2015-06-29T14:20:10.190" LastActivityDate="2015-06-29T21:00:01.240" Title="When is turbulence most dangerous to an aircraft?" Tags="&lt;safety&gt;&lt;turbulence&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16393" PostTypeId="2" ParentId="16387" CreationDate="2015-06-29T13:41:43.377" Score="11" Body="&lt;p&gt;They do this for the same reason they make you &lt;a href=&quot;http://gofar.aircanada.com/go-far-answers/question/earphones-during-ttl/&quot; rel=&quot;nofollow noreferrer&quot;&gt;put away all electronic devices&lt;/a&gt; during that period of flight. The first minutes of a flight (take off and climb out) as well as the last few (approach and landing) are the most critical and statistically the time that if things are going wrong they will go wrong. As such airlines shut down the IFE systems and ask users to shut down personal devices so that they can hear, and more importantly respond to any emergency directions that may be given during this critical time. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;2019 Update: Since this original answer was posted some &lt;a href=&quot;https://www.united.com/ual/en/us/fly/travel/inflight/devices.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;airlines now allow the use of &quot;small personal electronic devices&quot; in all phases of flight.&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2019-03-05T15:10:12.467" LastActivityDate="2019-03-05T15:10:12.467" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="16395" PostTypeId="2" ParentId="16392" CreationDate="2015-06-29T14:34:04.053" Score="2" Body="&lt;p&gt;Wake turbulence can affect aircraft in the most critical phases of flight such as landing approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, consider this &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Accident-Analysis/Accident-Statistics/EPilot-Reports/Wake-turbulence-rips-aircraft-apart&quot; rel=&quot;nofollow&quot;&gt;AOPA report&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On June 12, 2006, while on visual approach at Kansas City International Airport in Kansas City, Mo., the pilot of a Piper Saratoga crossed below the flight path of a Boeing 737 that was landing ahead on a parallel runway. The Saratoga encountered wake turbulence so violent that it tore apart the aircraft in flight. The pilot and his passenger were killed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The effects are most severe for small aircraft entering the wake of a large aircraft but large aircraft can be affected too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Skybrary &lt;a href=&quot;http://www.skybrary.aero/index.php/Accident_and_Serious_Incident_Reports:_WAKE&quot; rel=&quot;nofollow&quot;&gt;lists several examples&lt;/a&gt; of incidents involving wake turbulance.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-06-29T14:55:13.173" LastActivityDate="2015-06-29T14:55:13.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16396" PostTypeId="1" CreationDate="2015-06-29T14:54:04.637" Score="0" ViewCount="1224" Body="&lt;p&gt;Just wondering if this technology exists or has been attempted. For positioning purposes.&lt;/p&gt;&#xA;" OwnerUserId="9105" LastActivityDate="2015-06-29T16:46:37.417" Title="Is it possible to do a Live-stream web cam on an airplane over the oceans?" Tags="&lt;radio-communications&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-06-29T16:46:59.007" ContentLicense="CC BY-SA 3.0" />
  <row Id="16397" PostTypeId="2" ParentId="16396" CreationDate="2015-06-29T16:38:02.967" Score="0" Body="&lt;p&gt;There are multiple questions here &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Just wondering if this technology exists&lt;/strong&gt;: Yes it does, providers like &lt;a href=&quot;https://en.wikipedia.org/wiki/Gogo_Inflight_Internet&quot; rel=&quot;nofollow noreferrer&quot;&gt;GoGo Inflight Internet&lt;/a&gt; have systems in place to have internet connectivity on an airplane. You could, technically speaking use this channel to stream anything you wanted but you may hog bandwidth or see problems because of the way the bandwidth is allocated. From a purely technical standpoint it can be done.     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For positioning purposes:&lt;/strong&gt; This could be taken to mean a few things. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Where is the plane:&lt;/strong&gt; In this case video does nothing for you. There are no points of reference over the ocean so capturing footage of nothing leaves you with nothing. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Whats beneath the plane:&lt;/strong&gt; For the sake of SAR or simply checking up whats out there this can be done and as a matter of fact has been done. For what its worth the tech to do this is not cheap nor is it simple. Check out &lt;a href=&quot;https://aviation.stackexchange.com/questions/16320/how-did-sr-71-spy-flying-at-80-000-ft-and-3500-km-h/16333#16333&quot;&gt;this question about the SR-71&lt;/a&gt; which covers how the cameras worked pretty well. In short you need a camera that moves in sync with the plane so that the pictures come out clear. Granted the SR-71 used a film camera which could be replaced with a digital system the photographic element is not nearly as important as the system that moves it to make sure the photo is correct. Even then the SR-71 was sent on very specific missions over very specific places and the film was carefully post processed. Lets say you installed one of these systems on every plane out there (in one of those perfect worlds) the amount of time/computing power to process all that video in time to make use of it would be pushing if not over the limits of modern technology. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For reference here is &lt;a href=&quot;http://ambivalentengineer.blogspot.com/2013/04/optical-bar-cameras.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;the camera&lt;/a&gt; that the SR-71 used to photograph lots of area (they had another higher res one for smaller things). you could cut down the size these days since you would not need those huge film rolls for a digital system. Either way its a large precision machine (that Im sure is not cheap to operate or maintain).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sJX2p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-29T16:38:02.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16398" PostTypeId="2" ParentId="16396" CreationDate="2015-06-29T16:46:37.417" Score="2" Body="&lt;p&gt;No, there is no mid-ocean real-time streaming video useful for positioning purposes.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-06-29T16:46:37.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16399" PostTypeId="2" ParentId="16388" CreationDate="2015-06-29T16:54:08.050" Score="17" Body="&lt;p&gt;Three things come to mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Geometric shaping for stealth is based on the theoretical work of &lt;a href=&quot;https://en.wikipedia.org/wiki/Petr_Ufimtsev&quot; rel=&quot;noreferrer&quot;&gt;Petr Ufimtsev&lt;/a&gt;, a Russian mathematician who explained how to calculate the reflection of radio waves from the 1960s on.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://www.ausairpower.net/hmd-technology.html&quot; rel=&quot;noreferrer&quot;&gt;sight-controlled missile targeting&lt;/a&gt; which appeared in the MiG-29 in the 1980s. In combination with the wide off-boresight capabilities of the aircraft's radar and the missiles, it allowed to get a lock on aircraft flying actually behind it. When US F-16 met ex-GDR MiGs in exercises in the early 1990s, they were shocked to find &lt;a href=&quot;http://web.archive.org/web/20130330032841/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=8672&quot; rel=&quot;noreferrer&quot;&gt;how much superior&lt;/a&gt; the Russian design was and soon copied it.&lt;/li&gt;&#xA;&lt;li&gt;The rotating collars which were used on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Yakovlev_Yak-141&quot; rel=&quot;noreferrer&quot;&gt;Yak-141&lt;/a&gt; to deflect the engine exhaust straight down for vertical take-off have been used in the VTOL version of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;noreferrer&quot;&gt;F-35&lt;/a&gt;. Lockheed-Martin co-operated with Yakowlev in the early Nineties to learn how the Russian airplane works.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;From a historical perspective you can add the Russian (actually, Georgian) aircraft designer &lt;a href=&quot;https://en.wikipedia.org/wiki/Alexander_Kartveli&quot; rel=&quot;noreferrer&quot;&gt;Alexander Kartveli&lt;/a&gt;, who headed engineering at Republic, and the influence of Georgia-born &lt;a href=&quot;http://blog.nasm.si.edu/aviation/alexander-de-seversky/&quot; rel=&quot;noreferrer&quot;&gt;Alexander de Serversky&lt;/a&gt; (actually of Russian descent) who &lt;a href=&quot;http://www.waltdisney.org/blog/%E2%80%9Cdisney%E2%80%99s-greatest-film%E2%80%9D-walt-and-victory-through-air-power&quot; rel=&quot;noreferrer&quot;&gt;propagated strategic bombing&lt;/a&gt; to win future wars, even though this concerns bombers, not fighters.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-21T19:39:36.353" LastActivityDate="2015-09-21T19:39:36.353" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16400" PostTypeId="2" ParentId="16388" CreationDate="2015-06-29T17:08:10.967" Score="12" Body="&lt;p&gt;Variable wing geometry (&quot;swing wings&quot;) is a candidate. The U.S. Bell X-5 was the first aircraft to fly with a system for changing the sweep angle of the wings in flight; it was built based on a captured German aircraft whose wings could be adjusted on the ground. The Russians got wind of the X-5 program and copied the idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first production fighter on either side to fly with swept wings was the U.S. F-111 Aardvark fighter-bomber in 1964, however the Soviets were only 3 years behind with the first flight of their variable-geometry fighter, the Soviet MiG-23 interceptor, then the F-14 interceptor and MiG-27 ground-attack variant followed in 1970, with the B-1 penetration bomber and European Panavia Tornado multirole fighter in 1974 being the last swing-wing aircraft to enter production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Russians also tried to copy the U.S. XB-70 Valkyrie. For its day, this was a real threat to Russian air defenses, as it could theoretically fly above the faster low-level SAMs and outrun the high-altitude SAM systems the Soviets had at the time. Countering like-for-like to maintain MAD, the Soviets developed the Sukhoi T-4, which has an external design almost exactly matching the XB-70. The U.S. ended up cancelling the B-70 project as Soviet SAM advances and the MiG-25 interceptor made speed alone insufficient to fly over the USSR with impunity (the SR-71 also never overflew Soviet territory, to the best of civilian knowledge). Later on, the Soviets, in similar fashion to the Valkyrie project, would also copy the basic idea of the Space Shuttle to produce the Energia-Buran launch system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember hearing reports in the late Soviet era that Soviet MiG-29s and Su-27s had surpassed American radar technology and the Americans were struggling to catch up. The technological leap, IIRC, was passive electronically-scanned radar (PESA), which both sides had been using for ground and ship installations but the Soviets were the first to get the system small and self-contained enough for aircraft use. The Americans' fighters of the day (F-14, F-15, F-16, F-18) still used mechanically-scanned arrays with a moving antenna which slowed the scanning rate, especially in &quot;deep&quot; scanning modes (the tradeoff at the time was higher resolution; the F-15E's radar is capable of producing a map of the target zone from dozens of miles out, allowing the WSO to point the aircraft's targeting systems with extreme accuracy). The U.S. more or less leapfrogged the use of PESA radars in aircraft (only the B-1B and B-2 ever used them) and instead worked with the Japanese on AESA, which was first seen on Japan's F-2 variant of the F-16, and is used on later F/A-18 Super Hornet variants and the F-22 in the U.S. arsenal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly on my list, after the collapse of the Soviet Union, former Warsaw Pact territories including East Germany began sharing the technology the Soviets had left behind, and in some cases even bringing Soviet technology into NATO armed forces. Among the new information gained, the capabilities of the AA-11 Archer short-range IR missile system truly scared NATO top brass. The missile was more agile and had higher off-boresight capabilities than anything NATO was fielding at the time (most countries were at the time using the U.S.'s AIM-9M Sidewinder variant, which was good but demonstrably inferior especially in targeting). This was in part thanks to the helmet-mounted cueing system Peter Kampf mentioned, allowing a pilot to get a seeker lock on a target above or to the sides of his aircraft just by looking at it, instead of having to point the entire plane. The U.S. and NATO responded with the Joint Helmet Mounted Cueing System, the AIM-9X, and several other missile development programs including the MICA and ASRAAM, all borrowing from lessons learned by the AA-11.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-14T21:28:26.777" LastActivityDate="2015-09-14T21:28:26.777" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16402" PostTypeId="2" ParentId="14640" CreationDate="2015-06-29T17:41:23.420" Score="1" Body="&lt;p&gt;No, Carbonated drinks are generally not dangerous, and are labelled in such a way to let anyone who is transporting them know the contents of the carbonated drink. Before they become dangerous though, other factors would have had to happen that would be considered even more dangerous; The airline would have had to have a sudden change of pressure, such a change would cause a loss of consciousness for all those travelling on board the airline, and doing so would release CO2 from the cans.&lt;/p&gt;&#xA;" OwnerUserId="9117" LastEditorUserId="1467" LastEditDate="2015-06-29T17:48:31.383" LastActivityDate="2015-06-29T17:48:31.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16403" PostTypeId="2" ParentId="12876" CreationDate="2015-06-29T17:48:53.580" Score="0" Body="&lt;p&gt;Southwest Airlines name some but not all of their aircraft; these are typically either limited runs for marketing (such as the Sea World, NBA and Sports Illustrated partnerships), aircraft dedicated to a particular state in Southwest's &quot;home territory&quot; (Arizona One, California One, Missouri One, New Mexico One, Lone Star One, etc), or else the first planes in some significant change to Southwest's fleet (Heart One and Heart Two were the first to be painted in the Heart livery that replaced the earlier Canyon Blue; the first Canyon Blue livery, in turn, was borne by Spirit One). A few are &quot;signature planes&quot; dedicated to notable Southwest employees or aviation figures in general, such as Fred J Jones. The full list of special liveries is on &lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines#Special_liveries_and_decals&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-29T17:48:53.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16404" PostTypeId="2" ParentId="15529" CreationDate="2015-06-29T18:22:20.960" Score="5" Body="&lt;p&gt;I think that there would be little practical impact, except for those people who are heavily invested in DTC DUATS specifically and have to switch to another system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, there are two DUATS providers: &lt;a href=&quot;https://www.duat.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;DTC&lt;/a&gt; and &lt;a href=&quot;https://duats.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;CSC&lt;/a&gt;. Even if DTC goes away, CSC is still available, at least for now, and it provides exactly the same service as DTC (see &lt;a href=&quot;https://aviation.stackexchange.com/q/11387/62&quot;&gt;this question&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, &lt;a href=&quot;https://www.1800wxbrief.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin Flight Service&lt;/a&gt; (LMFS) provides all of the information and flight plan filings that DUATS does, and also provides briefings with a human briefer. So there is a completely separate alternative to DUATS available, although admittedly switching tools always has some cost in terms of time and learning at least.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume the main impact would be on people who use DTC DUATS as their primary flight planning and filing tool and use it directly, rather than via another tool. For example, I use Garmin Pilot with CSC DUATS but I could switch to DTC simply by changing the data provider option. Some flight planning tools also &lt;a href=&quot;https://foreflight.com/support/faqs/search/?q=flight%20plan&quot; rel=&quot;nofollow noreferrer&quot;&gt;support LMFS flight plan filing&lt;/a&gt; and I guess that more and more will in future, if only for competitive reasons. But if you use the DTC DUATS website directly and are very experienced and comfortable with it then switching to LMFS or anything else would have a learning curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in the end, people won't quit flying or even cancel flights just because DTC goes away. They'll just complain a bit, choose a new platform (probably LMFS) and get on with it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-06-29T18:22:20.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16405" PostTypeId="2" ParentId="16233" CreationDate="2015-06-29T18:34:28.140" Score="0" Body="&lt;p&gt;For small airplanes as you said it is used DC generation mainly to feed the battery which provides energy for the starter generator. I do not know of such airplanes having DC generation &lt;strong&gt;and&lt;/strong&gt; the inverter for AC but I know that the &lt;strong&gt;ART-42&lt;/strong&gt; uses double generation DC and AC as well.&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="8399" LastEditDate="2015-07-01T15:13:33.173" LastActivityDate="2015-07-01T15:13:33.173" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16406" PostTypeId="2" ParentId="16376" CreationDate="2015-06-29T19:38:01.537" Score="2" Body="&lt;p&gt;The simplest answer is that the error introduced by gyroscopic precession is not considered significant during normal aircraft operation (maintaining relatively normal flight attitudes, i.e. within 30* of level flight). There is a mechanism designed to automatically re-orient the gyroscope during flight, called a &quot;caging mechanism&quot;, which normally works very well but during sustained maneuvers it can actually exacerbate precession error. The caging mechanism can usually be activated manually in VMC (or at least when the horizon is visible) with a &quot;push to cage&quot; button to ensure the AI matches the real horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically, the error induced by precession over time could add up to be significant. Violent maneuvers increase the effects of friction and precession in the gimbal system and can cause it to lock or tumble. These situations are unlikely to happen undetected by the pilot, for several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots flying by instruments don't use just one of them; there is some overlap in what the instruments should be telling you. For instance, at an indicated &quot;cruising&quot; airspeed where AOA is low, if the AH indicates level flight but the VVI or altimeter say you're sinking, or the TC indicates bank or any of your course indicators (DG, CDI/OBI etc) indicate a change in heading not mirrored by the slip indicator, that casts doubt on the accuracy of the horizon.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;During IFR flight, the pilot is required to coordinate with ATC. In most cases, ATC can detect on radar that a plane is deviating from course, and will advise the pilot of this and coordinate with him to resolve the problem, including diagnosing any instrument failures that may have led to the deviation in the first place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots, no matter how experienced with instruments, don't like flying in IMC. It's just no fun; it requires a high level of concentration and a basic departure from the &quot;trust your senses&quot; mentality that has been the survival mantra for the human race for millenia. The potential for pilot error is high. Pilots will therefore seek to minimize their time in IMC by working with ATC to climb above or navigate around regions of IMC.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Modern instruments incorporate solid-state accelerometers and magnetometers as well as gyroscopes as the basis for the inertial navigation system, especially for the AHRS subsystem of glass cockpits. Gyroscopes may still be present in the system but they can be much more easily detected to be out of calibration and corrected by the computer. The horizon indicator included in modern &quot;primary flight displays&quot;, therefore, is pretty trustworthy.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-29T19:38:01.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16408" PostTypeId="2" ParentId="16379" CreationDate="2015-06-29T20:06:00.650" Score="5" Body="&lt;p&gt;The biggest two reasons to have a stabilator (the most common all-moving control surface) are stability at supersonic speeds and increased maneuverability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an airfoil approaches its critical Mach number, the diverted flow moving past the wing's leading edge, because it has to move faster than the wing itself to follow the contour, starts to exceed Mach 1 and then decelerates below it, causing a transsonic shockwave to form behind the wing's leading edge. This shockwave causes boundary separation of the airflow at the trailing edge of the wing, where traditional elevator surfaces are placed. This reduces the wing's lift and also the effectiveness of elevator surfaces, a phenomenon known as &quot;Mach tuck&quot;. By instead moving the entire control surface, this problem is avoided as the entire airfoil, regardless of the quality of the flow of air over any point of it, is used to direct airflow and thus rate the aircraft's nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, and more intuitively, the larger the elevator surface, the more air it redirects and thus the more force it places on the tail section, in turn allowing the pilot to pitch the aircraft at higher rates. The ideal endpoint of this line of thought is that the entire stabilizer also becomes the elevator surface; a &quot;stabilator&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both of these considerations are critical to the design of fighter jets, which as of the fourth generation were almost all capable of Mach 1 (and a few could exceed Mach 2), and which also have to be highly maneuverable even as the moment of inertia of the airframe in the pitch plane increases (an unavoidable side effect of wrapping an airframe around two high-performance jet engines traversing the length of the fuselage).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-29T20:06:00.650" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16409" PostTypeId="2" ParentId="1645" CreationDate="2015-06-29T20:45:21.627" Score="1" Body="&lt;p&gt;The turn coordinator or turn and slip indicator (they are different) usually are electric powered.  The artificial horizon is usually vacuum driven.  If you replace the turn coordinator with an artificial horizon, it should be electric, assuming the existing one is vacuum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rate gyros are not prone to gimbal lock, or &quot;toppling&quot;, as are most attitude indicators.  If an attitude indicator topples, it can take several minutes to correct.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, read 91.205.  Generally, a gyroscopic rate-of-turn indicator (needle) and a slip-skid indicator (ball) are required for IFR flight.  Two attitude indicators won't do.  &lt;/p&gt;&#xA;" OwnerUserId="9120" LastEditorUserId="9120" LastEditDate="2015-06-29T21:05:25.287" LastActivityDate="2015-06-29T21:05:25.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16410" PostTypeId="1" AcceptedAnswerId="16426" CreationDate="2015-06-29T20:45:33.407" Score="18" ViewCount="4514" Body="&lt;p&gt;I know that the F-16 VISTA tech demonstrator incorporated 2D thrust vectoring and could perform this maneuver. I also know that military variants of the F-16 are prevented from intentionally entering such extreme angles of attack via their flight limiters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I also know one more thing; there is a switch just in front of the throttle that allows &quot;manual pitch override&quot;. This disables the pitch-plane limiter of the FLCC to allow the pilot to recover from certain types of deep stalls when normally the flight limiters would freeze the control surfaces due to the detected extreme AOA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, can U.S. military-variant F-16s, with MPO enabled, perform a &quot;Cobra&quot; maneuver like Pugachev's Cobra?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="15311" LastEditDate="2017-12-06T13:32:50.913" LastActivityDate="2017-12-06T13:32:50.913" Title="Can an F-16 perform Pugachev's Cobra?" Tags="&lt;military&gt;&lt;aerobatics&gt;&lt;f-16&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16411" PostTypeId="2" ParentId="16392" CreationDate="2015-06-29T21:00:01.240" Score="1" Body="&lt;p&gt;Turbulence is most dangerous when landing, or when it is extreme.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A sudden downdraft during landing can cause a plane to crash, notably the Dallas crash of &lt;a href=&quot;https://en.wikipedia.org/wiki/Delta_Air_Lines_Flight_191&quot; rel=&quot;nofollow&quot;&gt;Delta 191&lt;/a&gt;, in which most of the people aboard died.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside of storms turbulence can become so violent that it is threatening to the structural integrity of the aircraft. Although planes can and do fly inside of hurricanes and other violent storms, if the pilot makes a mistake and gives the wrong input, control surfaces can be damaged or destroyed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence can often be quite violent near mountains, downdrafts produced by rotors and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lee_wave&quot; rel=&quot;nofollow&quot;&gt;lee waves&lt;/a&gt; being particularly dangerous. Expert pilot &lt;a href=&quot;https://en.wikipedia.org/wiki/Steve_Fossett&quot; rel=&quot;nofollow&quot;&gt;Steve Fossett&lt;/a&gt; was killed in that way. Even large planes have been destroyed by mountain winds such as &lt;a href=&quot;https://en.wikipedia.org/wiki/BOAC_Flight_911&quot; rel=&quot;nofollow&quot;&gt;BOAC Flight 911&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence in combination with a low-visibility condition, such as a storm, can also cause a pilot to become disoriented.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-29T21:00:01.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16412" PostTypeId="2" ParentId="16365" CreationDate="2015-06-29T21:31:36.743" Score="-1" Body="&lt;p&gt;Most missiles do not have better agility than planes. The maneuverability of an flight vehicle is defined typically by what is called a &quot;maneuverability graph&quot;. Aircraft generally have much better maneuverability than traditional missiles do, but there are some newer missiles that use a technology called &quot;Thrust-Vector Control&quot; which can potentially make the missiles more agile in some, but not all, parts of the envelope. In general missiles achieve their lethality by greater speed, not greater maneuverability.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-06-29T21:31:36.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16413" PostTypeId="1" AcceptedAnswerId="16423" CreationDate="2015-06-29T21:54:37.860" Score="5" ViewCount="443" Body="&lt;p&gt;I have tried &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;drinking a glass of water&lt;/li&gt;&#xA;&lt;li&gt;yawning&lt;/li&gt;&#xA;&lt;li&gt;plugging my nostrils and pushing air&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;but none of these seem to work - I still have a distinct pain in my upper sinus cavities when changing pressure in an airplane. I have the same pain underwater. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do some pilots have this problem, and do they have a remedy? &lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="5517" LastEditDate="2016-05-26T12:19:17.170" LastActivityDate="2016-05-26T13:41:18.100" Title="How do pilots cope with pressurization changes?" Tags="&lt;medical&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16414" PostTypeId="1" AcceptedAnswerId="16415" CreationDate="2015-06-29T23:30:01.577" Score="6" ViewCount="2322" Body="&lt;p&gt;I'm checking out the Dallas sectional in digital form for my own amusement. The image, in TIFF format, is massive. I wonder, if you buy one of these in printed form from the FAA (or your local GA office), what would be the sheet size of the map? &lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="62" LastEditDate="2015-06-30T01:49:10.540" LastActivityDate="2015-06-30T01:49:10.540" Title="What's the standard print size for a sectional chart?" Tags="&lt;usa&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16415" PostTypeId="2" ParentId="16414" CreationDate="2015-06-29T23:56:38.750" Score="6" Body="&lt;p&gt;The New York Sectional (the only paper one I have on hand right now) is 20 3/4 X 59 1/4 inches. You are correct, they are large and printed on nice thick paper. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-06-30T01:38:55.053" LastActivityDate="2015-06-30T01:38:55.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16416" PostTypeId="1" AcceptedAnswerId="16422" CreationDate="2015-06-29T23:56:46.740" Score="8" ViewCount="671" Body="&lt;p&gt;Looking at the Washington sectional, several areas offshore are designated &quot;Warning&quot; areas: W-386, W-107, W-105 etc. The only notes given are &quot;National Defense Operating Areas. Operations hazardous to the flight of aircraft conducted within these areas&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That would be enough to keep me well ashore, but out of morbid curiosity, what kind of activities are we talking about? Are these areas designated for naval gunnery/missile ranges?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="1696" LastEditDate="2015-07-21T16:29:57.500" LastActivityDate="2015-07-21T16:29:57.500" Title="What activities take place in the warning areas offshore of Washington, D.C.?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16417" PostTypeId="2" ParentId="16376" CreationDate="2015-06-30T00:29:44.923" Score="14" Body="&lt;p&gt;A gyroscopic AI has an erection mechanism, which continuously corrects the AI to be upright based on the local level, or downward acceleration vector. The correction rate is generally 3-5 degrees per minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way that the AI corrects itself is a system of pendulous vanes. When the gyro is not upright relative to the local level, centrifugal force pushes open vanes on the gyro's case. Air escapes through the uncovered holes, applying a force to the case, and correcting for precession.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/yUQLB.png&quot; alt=&quot;Gyroscope emphasizing pendulous vanes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_65-15A.pdf&quot; rel=&quot;noreferrer&quot;&gt;(FAA AC 65-15A)&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second half is somewhat counter-intuitive, but flying in a coordinated turn will not continuously increase the error in the AI. For the first half of the turn, the AI will add error; in the second half, it removes the error. After a 360 degree turn, the precession error will be removed completely. For more detail, see another answer: &lt;a href=&quot;https://aviation.stackexchange.com/q/14657/136&quot;&gt;If I fly a balanced turn long enough, will the AI show I'm level?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-06-30T00:57:48.057" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16418" PostTypeId="1" AcceptedAnswerId="16421" CreationDate="2015-06-30T00:31:48.760" Score="7" ViewCount="2555" Body="&lt;p&gt;On the Dallas-Fort Worth sectional, notice one of the few permanently Prohibited airspace zones west of the Mississippi; P-47, around the PanTex nuclear plant in Amarillo, just northwest of Husband Intl (AMA) and within the outer cylinder of its Class C space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, that zone is directly in the path of AMA's longer runway, 4/22, and Victor routes including V12-280 extend directly away from the PNH VORTAC at AMA right over the top of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That leads me to think that either P-47 has a ceiling above which airliners are allowed to operate, or else AMA Approach and Fort Worth Center via Amarillo RCO have a dickens of a time routing incoming traffic when the winds indicate use of runway 4/22. The outer Charlie cylinder begins at 4800 feet, but the chart also clearly states that P-47 is excluded from AMA's class C space where they overlap. That leads me to think that this P-space extends to Jupiter, and all flight traffic including AMA arrivals/departures (it's not a big town, but it's not exactly BFE either in part because of Pantex) have to maneuver specifically to avoid P-47.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to confirm, is there any altitude at which you can overfly P-47, or in more general terms any P-zone? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems kind of silly for many P-zones, including this one, to extend all the way to space, as beyond a certain altitude if nothing else it becomes impractical to dive straight down into the facility under protection. But, if that's the law...&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="19" LastEditDate="2017-01-16T15:58:41.637" LastActivityDate="2017-01-16T15:58:41.637" Title="What is the ceiling to prohibited space P-47 (or any other P-zone)?" Tags="&lt;faa-regulations&gt;&lt;navigation&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16421" PostTypeId="2" ParentId="16418" CreationDate="2015-06-30T00:57:00.880" Score="7" Body="&lt;p&gt;Special Use Airspace is defined by boundaries in all three dimensions&lt;sup&gt;1&lt;/sup&gt;. The horizontal boundaries are depicted on the chart as you describe. The vertical boundaries are in the sidebar of the chart:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uA9wF.png&quot; alt=&quot;SUA chart from the Dallas Ft. Worth Sectional&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see here that P-47 exists from the surface (because there's nothing before the &quot;TO&quot;) up to 4800 MSL. KAMA is at at 3607 MSL, so P-47 ends 1200' above the airport surface. At a little more than 5 NM away from the airport (measuring on the sectional), that's about 240 ft/NM climb: well within the performance capabilities of almost every powered aircraft. Overflights on the victor airway obviously have no problem at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is used for allowing traffic where it might otherwise not be possible: Consider P-40 and R-4009, above Camp David in Maryland. When the President is not in residence, R-4009 lies exactly on top of P-40. P-40, from the surface to 5,000, is a no-fly zone. R-4009, from 5,000 to 12,500, can be transited with ATC permission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1)There's always an exception: see R-2933, over Cape Canaveral: 5,000 to UNLIMITED.&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-06-30T00:57:00.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16422" PostTypeId="2" ParentId="16416" CreationDate="2015-06-30T02:26:39.127" Score="8" Body="&lt;p&gt;Answering my own question, these areas are designated for a variety of naval training and testing exercises including missile launches and heavy guns firing, which is the primary reason it's hazardous. The airspace can be traversed under guidance from either Washington Center or FACSFAC VACAPES, but entry by VFR aircraft without established comms is not recommended.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-06-30T02:26:39.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16423" PostTypeId="2" ParentId="16413" CreationDate="2015-06-30T04:44:28.047" Score="4" Body="&lt;p&gt;There is a chance you suffer from &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerosinusitis&quot; rel=&quot;nofollow&quot;&gt;aerosinusitis&lt;/a&gt; but you should consult a physician to obtain a proper diagnosis (Disclaimer: I am NOT a doctor). For what its worth commercial planes are pressurized generally to about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cabin_pressurization#Cabin_altitude&quot; rel=&quot;nofollow&quot;&gt;pressure you would see at 8000 ft.&lt;/a&gt; this equates to about .75 Atm. In the reverse case 33ft underwater already has you at 2 Atm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I fly (generally unpressurized) I usually chew gum which i find helps. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-30T04:44:28.047" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16424" PostTypeId="1" AcceptedAnswerId="16425" CreationDate="2015-06-30T05:49:41.433" Score="7" ViewCount="1124" Body="&lt;p&gt;Several years ago I was a passenger on a near cross-country flight when the pilot came on the PA and announced that we were climbing towards our cruise altitude, on autopilot, and as our fuel load was burning off, and the plane's weight lessened, we would be climbing about another five thousand feet from our cruise altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wondered why the autopilot, instead, would not make micro-adjustments to the angle of attack to maintain the same altitude, rather than waste fuel making an unnecessary climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that maintaining the same exact altitude is probably not realistic, but autopilot, I would think, ought to be able to maintain cruise altitude within about one thousand feet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was on a Southwest flight, so it had to be a Boeing 737.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastEditorUserId="1289" LastEditDate="2015-06-30T08:30:25.607" LastActivityDate="2015-06-30T13:30:55.447" Title="Why do airliners on autopilot climb during cruise?" Tags="&lt;autopilot&gt;&lt;angle-of-attack&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16425" PostTypeId="2" ParentId="16424" CreationDate="2015-06-30T06:06:24.440" Score="11" Body="&lt;p&gt;Climbing further while cruising is saving fuel, not wasting it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, every airplane has an &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;optimum angle of attack&lt;/a&gt; for most economical cruise. If it loses mass (due to fuel consumed), it needs to adjust either its altitude or its speed to keep that angle of attack. The goal is to keep dynamic pressure, the product of air density and the square of airspeed, constant. Since you want to reach your destination in the shortest time, climbing into less dense air is the better option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, gas turbines need less fuel per unit of thrust when flying in colder air. As long as the plane stays in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Troposphere&quot; rel=&quot;nofollow noreferrer&quot;&gt;troposphere&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;it will fly more economically&lt;/a&gt; when it flies in colder air.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-06-30T06:06:24.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16426" PostTypeId="2" ParentId="16410" CreationDate="2015-06-30T07:42:07.947" Score="19" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would require a docile pitch behavior of the airframe up to approx. 110° angle of attack. The &lt;a href=&quot;http://tsagi.com/institute/index.php?sphrase_id=8960&quot;&gt;design of both the Su-27 and the MiG-29&lt;/a&gt; is based on a geometry that has been carefully optimized by &lt;a href=&quot;http://www.tsagi.com&quot;&gt;TsAGI&lt;/a&gt; to behave nicely over its full AoA range, a care that has not been spent by &lt;a href=&quot;http://www.airspacemag.com/military-aviation/outrageous-adolescence-f-16-180949491/?no-ist&quot;&gt;General Dynamics while designing the F-16&lt;/a&gt;. The specifications did not call for it, because the idea was to create a low-cost lightweight fighter to complement the heavy F-15.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, even the F-15 is AoA limited because less care was spent on its aerodynamic refinement. At higher angles of attack, both the F-16 and the F-15 show a nasty pitch-up which cannot be controlled with the aerodynamic control surfaces - only thrust vectoring can manage this. Contrast this which the Su-27, which shows balanced and slightly negative (nose down) pitch moments over the full AoA range, so the limited control authority coupled with the aircraft's dynamics can make the Cobra maneuver possible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-06-30T07:53:10.600" LastActivityDate="2015-06-30T07:53:10.600" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16427" PostTypeId="1" AcceptedAnswerId="16429" CreationDate="2015-06-30T08:07:52.650" Score="20" ViewCount="9883" Body="&lt;p&gt;From my own understanding, the bigger (and heavier) aircraft, the higher approach speed it needs to keep itself from stalling. According to &lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-stopping-the-a380-27549065/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;this site&lt;/a&gt;, the approach speed of an A380 is 140 knots, and 160 knots for a 747. In contrast, the F-16's &lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?t=5252&quot; rel=&quot;noreferrer&quot;&gt;landing speed&lt;/a&gt; is 141 knots, and 135 knots for the F-35C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing mass-to-speed ratio, it doesn't make any sense to me. Could you explain why do fighter jets land faster while they are lighter than large commercial aircraft?&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="1049" LastEditDate="2015-07-01T11:21:07.463" LastActivityDate="2019-10-30T12:48:17.323" Title="Why do fighter jets land faster than Jumbo commercial aircraft?" Tags="&lt;approach&gt;&lt;airspeed&gt;" AnswerCount="5" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16428" PostTypeId="2" ParentId="16427" CreationDate="2015-06-30T08:22:45.370" Score="4" Body="&lt;p&gt;Because they are lighter, they have less kinetic energy so there is less to dissipate. This is easier on the brakes. Remember &lt;a href=&quot;https://en.wikipedia.org/wiki/Kinetic_energy&quot; rel=&quot;nofollow&quot;&gt;kinetic energy&lt;/a&gt; is $E_k=\frac{m \cdot v^2}{2}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also fighter jets aren't as good gliders as jumbo jets. This sacrifices lift for maneuverability, so they have better acrobatic performance. While airliners will spend most of their airtime going straight ahead at high altitude so they benefit the most from being good gliders.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="849" LastEditDate="2015-06-30T19:23:21.590" LastActivityDate="2015-06-30T19:23:21.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16429" PostTypeId="2" ParentId="16427" CreationDate="2015-06-30T08:54:39.803" Score="26" Body="&lt;p&gt;It is not only the mass that affects the landing speed. Wing area plays an important role as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A larger wing can lift more weight at the same speed than a smaller wing. If you compare the wing loading of these aircraft the differences are smaller:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A388:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum landing weight: 391000 kg&lt;/li&gt;&#xA;&lt;li&gt;Wing area: 845 m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;Wing loading: 463 kg/m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;B744:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum landing weight: 295000 kg&lt;/li&gt;&#xA;&lt;li&gt;Wing area: 525 m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;Wing loading: 468 kg/m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;F-16A:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Estimated landing weight: 13000 kg&lt;/li&gt;&#xA;&lt;li&gt;Wing area: 28 m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;li&gt;Wing loading: 464 kg/m&lt;sup&gt;2&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-22T14:27:24.767" LastActivityDate="2015-09-22T14:27:24.767" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16430" PostTypeId="1" AcceptedAnswerId="16431" CreationDate="2015-06-30T08:57:26.973" Score="19" ViewCount="7258" Body="&lt;p&gt;Yesterday, I flew on Germanwings 4U2379 with an Airbus A319. The plane's interior looked pretty modern, and while I can't find a construction year online, I'm pretty sure it was built way after the total smoking ban. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This plane still had illuminated non-smoking signs though and I was wondering if the crew would actually be able to turn these off during flight if they wanted to. Is there any information about that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9516/what-was-the-reason-for-replacing-the-non-smoking-sign-with-a-non-electronic-sig&quot;&gt;This question&lt;/a&gt; shows that some planes do not even have a non-smoking sign anymore, but it does not elaborate on the mechanics of existing signs.&lt;/p&gt;&#xA;" OwnerUserId="9127" LastActivityDate="2020-11-28T20:42:57.577" Title="Could the non-smoking sign still be turned off in modern airplanes?" Tags="&lt;airbus-a320&gt;&lt;cabin-design&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16431" PostTypeId="2" ParentId="16430" CreationDate="2015-06-30T09:29:33.110" Score="25" Body="&lt;p&gt;It would appear that the aircraft you flew was D-AGWR, a A319 with MSN (Manufacturer Serial Number) 4285 delivered in April 2010 (hence fairly new).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There is a switch at the bottom of the overhead panel, next to the seat belt sign, slightly right of the middle. Flip it and they will extinguish. The functionality is a bit more complicated than it would appear, since it feeds into the central aircraft electronics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/760ec.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/760ec.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Overhead_panel_of_an_Airbus_A320_during_cruise.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Olivier Cleynen at Wikicommons&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Out of interest, this button no longer exists on the Boeing B787, suggesting that it is on the way out. Only the seat belt option remains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slots for no smoking are being increasingly 'redeveloped' into a sign for electronic devices instead on some types. They just put a no smoking sticker on the seat in front of you to fulfil the same function. I do not know if they cockpit text has been modified on the aircraft that undergo this modification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://1.bp.blogspot.com/-p5X_V-A1wJE/TothZttJVUI/AAAAAAAAANk/FRTdKUghPog/s640/Sommer+2011+1056.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://ifly2.blogspot.nl/2011/10/air-frances-voyageur-class-oslo-paris.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="14897" LastEditDate="2017-05-02T14:46:24.757" LastActivityDate="2017-05-02T14:46:24.757" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16432" PostTypeId="2" ParentId="16427" CreationDate="2015-06-30T09:44:45.140" Score="11" Body="&lt;p&gt;Landing speed varies depending on several factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airliners you have to take into account that the wing airfoil is radically different than the wing airfoil from a fighter jet: airliners have flaps that modifies the airfoil and doing so the lift and trail (not sure of this word in English) modifying the speed range of the wing (reducing the stall speed) and so allowing slower speed for landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a fighter jet the wing is in general a delta wing without flaps, so in order to reduce the speed for landing they have to increase the angle of attack to augment the trail without loosing too much lift. That why in this phase they cannot lower too much the engines and the speed, because their wings are not suited for low speeds. If you look at the Concorde (a good example of delta wing) they had to put down the nose during landing phase to be able to see the runway because of the high attack angle requested to be at the right speed (about 180-190&amp;nbsp;kt).&lt;/p&gt;&#xA;" OwnerUserId="9128" LastEditorUserId="849" LastEditDate="2015-06-30T19:27:50.510" LastActivityDate="2015-06-30T19:27:50.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16433" PostTypeId="2" ParentId="16430" CreationDate="2015-06-30T11:59:10.133" Score="12" Body="&lt;p&gt;&lt;em&gt;In extremis&lt;/em&gt;, every electrical item on a plane can be switched off, to protect the plane if the item malfunctions. For example, a short-circuit in the no smoking signs could, in principle, cause a fire. At the very least, there will be a circuit breaker that can be removed to remove power from the signs. However, I don't know if there would be an individual breaker for that system: there might be a single breaker that isolates several related systems.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-06-30T11:59:10.133" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16434" PostTypeId="1" AcceptedAnswerId="16435" CreationDate="2015-06-30T12:37:33.573" Score="82" ViewCount="45468" Body="&lt;p&gt;Almost all cockpit panels of Russian aircraft types are painted in turquoise, whereas elsewhere the cockpit panels usually exhibit a dark grey color.&#xA;As this &quot;rule&quot; seems to be quite prevalent, I am curious as to the reason/origin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be seen in the cockpit of &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-31&quot; rel=&quot;noreferrer&quot;&gt;Mikoyan MiG-31&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XKtET.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XKtET.jpg&quot; alt=&quot;MiG-31 cockpit&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Cockpit_of_Mikoyan-Gurevich_MiG-31_(2).jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3964" LastEditorUserId="65" LastEditDate="2015-07-28T15:07:41.827" LastActivityDate="2020-04-06T19:10:09.207" Title="Why are Russian cockpit panels painted in turquoise?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;cockpit&gt;&lt;russia&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16435" PostTypeId="2" ParentId="16434" CreationDate="2015-06-30T13:13:43.047" Score="81" Body="&lt;p&gt;According to &lt;a href=&quot;http://blog.cwam.org/2010/03/migs-and-mils-cockpit-color.html&quot;&gt;Cold War Air Museum&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the color chosen by Soviet designers helps to reduce stress and&#xA;  maintain a pilot's effectiveness on long missions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... the scientists found out that this color keeps pilots awake and&#xA;  not getting tired by the black or grey of a cockpit panel, especially&#xA;  under terms and condition of long range flights or under heavy work&#xA;  load.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cybermodeler.com/color/cockpit.shtml&quot;&gt;This URL&lt;/a&gt; contains a color guide for cockpits.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-06-30T13:13:43.047" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16436" PostTypeId="2" ParentId="16424" CreationDate="2015-06-30T13:30:55.447" Score="6" Body="&lt;p&gt;Along with engine economy they may also have been climbing to take advantage of &lt;a href=&quot;https://en.wikipedia.org/wiki/Winds_aloft&quot; rel=&quot;noreferrer&quot;&gt;winds aloft&lt;/a&gt; at that altitude. Lets take a look at todays winds aloft out of JFK as an example&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FD1US1&#xA;DATA BASED ON 300600Z&lt;br /&gt;&#xA;VALID 301200Z   FOR USE 0800-1500Z. TEMPS NEG ABV 24000&lt;/p&gt;&#xA;&lt;p&gt;FT  3000    6000    9000   12000   18000   24000  30000  34000  39000&lt;/p&gt;&#xA;&lt;p&gt;JFK 2109 2109+10 2614+06 2521+01 2341-10 2348-22 235536 245645 246456&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;We can see that the winds at 34000 are 240 @ 56 and another 5000 feet up at 3900 are 240 @ 64 a solid 8 knot increase. Over a long distance this can make a big difference.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-06-30T13:30:55.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16437" PostTypeId="1" AcceptedAnswerId="16439" CreationDate="2015-06-30T14:37:02.790" Score="16" ViewCount="22650" Body="&lt;p&gt;Why do all the airplanes have to retract their landing gear, once they reach some specific height? Why can't they simply leave their landing gear deployed all through the flight?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2016-06-11T04:00:36.297" Title="Why do airplanes have to retract landing gear?" Tags="&lt;landing-gear&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16438" PostTypeId="2" ParentId="16437" CreationDate="2015-06-30T14:42:43.637" Score="15" Body="&lt;p&gt;Because its a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerodynamic_drag&quot; rel=&quot;noreferrer&quot;&gt;drag&lt;/a&gt; to leave it down(pun intended). Some smaller GA planes (and big planes too) can extend the landing gear through a wide range of their operating speeds and use them as a pretty effective speed break. &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2006/November/1/Diamond-Aircraft-DA42-Twin-Star&quot; rel=&quot;noreferrer&quot;&gt;The DA42&lt;/a&gt; comes to mind in this regard.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth there are many general aviation planes that have fixed gear. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/MhoAw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Retracting gear in a small plane has always been an interesting topic. Some older piston singles have manual retracting gear like the early &lt;a href=&quot;https://en.wikipedia.org/wiki/Mooney_M20&quot; rel=&quot;noreferrer&quot;&gt;Mooney M20's&lt;/a&gt; which used a Johnson bar to retract the gear. This some what dated system is, by some very sought after for its simplicity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(the big silver bar in the middle is the gear lever)&#xA;&lt;img src=&quot;https://i.stack.imgur.com/20BBw.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Folding gear also has little to do with aircraft size. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Mooney_M-18_Mite&quot; rel=&quot;noreferrer&quot;&gt;Mooney M-18 &quot;Mite&quot;&lt;/a&gt; which is a tiny plane by anyones standards had retractable gear (also Johnson bar operated). &#xA;&lt;img src=&quot;https://i.stack.imgur.com/IzoJK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to reduce drag on a fixed gear plane is through the use of gear fairings. while they do help with speed they can also cause an issue if the plane touches down hard. In some cases (if the wheel is improperly inflated) a hard touchdown or bounce will cause the wheel to balloon out while also spinning which could chafe or seriously damage the fairing. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/tJIsJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-01T11:57:31.107" LastActivityDate="2015-07-01T11:57:31.107" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16439" PostTypeId="2" ParentId="16437" CreationDate="2015-06-30T15:06:40.393" Score="28" Body="&lt;p&gt;In the early days of aviation it was simply easier to have the gear fixed. The landing gear adds drag, but so does &lt;a href=&quot;https://en.wikipedia.org/wiki/Biplane&quot; rel=&quot;noreferrer&quot;&gt;a second wing&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Flying_wires&quot; rel=&quot;noreferrer&quot;&gt;wire braces&lt;/a&gt;. Airplanes generally did not fly very fast or far, so the drag from the landing gear (and that other stuff) was not a big issue. The first design with retractable gear &lt;a href=&quot;https://aviation.stackexchange.com/q/13231/1696&quot;&gt;dates to 1911&lt;/a&gt;. Since then, retractable gear has been a design decision each airplane must make.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Retracting the gear into the airplane allows for a cleaner form, which reduces drag. However, this is at the expense of added weight. The retract system, which is usually hydraulic, must be added, and the plane must be designed to make room for the gear somewhere at least mostly inside the aircraft. The plane must also be designed to handle situations where some or all of the gear does not extend properly. For planes that need to be fast and/or efficient, retractable gear is worth the reduction in drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The additional drag has to be supported by the structure as well. Aircraft with retractable gear will have a maximum speed at which the gear can be extended. Even gear with proper fairings would add significant drag at the speeds airliners fly at. This would be much more critical at supersonic speeds. In these cases the weight of reinforcing the gear could be even higher than the weight of the retracting system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Particularly smaller general aviation planes tend to not have retractable gear. The retract system adds extra weight and complexity (and therefore cost), which will be fairly significant in a small plane. Fixed gear is simple and can be designed to minimize drag as much as possible. These planes do not typically need to fly fast or have large range, so the added drag is less of an issue. Other small planes do have retractable gear, which will allow for greater speed and range. The PA-32 type shown in &lt;a href=&quot;https://aviation.stackexchange.com/a/16438/1696&quot;&gt;Dave's answer&lt;/a&gt; was later produced in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-32R&quot; rel=&quot;noreferrer&quot;&gt;retractable gear version&lt;/a&gt; as well.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-30T19:22:13.980" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16440" PostTypeId="2" ParentId="16430" CreationDate="2015-06-30T15:25:07.940" Score="2" Body="&lt;p&gt;One option, used by at least some airlines, is that while the lighted &quot;no smoking&quot; signs have been replaced by placards (no lightbulbs to ever need replacing), the cockpit switch itself still works in that it produces a single tone chime when turned on or off. Since this chime is audibly distinct from the usual high-low F/A Call chime, it could be used as a method of notifying the cabin crew (although I don't know if or how often it's actually employed that way).&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-06-30T15:25:07.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16441" PostTypeId="1" AcceptedAnswerId="16451" CreationDate="2015-06-30T15:29:10.340" Score="13" ViewCount="93820" Body="&lt;p&gt;How can one determine the registration number (i.e. N123AA) of the aircraft used on a particular flight, having the date, airline, flight number and city pair to start with?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="62" LastEditDate="2015-06-30T17:12:35.653" LastActivityDate="2016-10-02T04:04:07.700" Title="How to determine the aircraft tail number on a particular flight?" Tags="&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16442" PostTypeId="2" ParentId="16441" CreationDate="2015-06-30T15:59:52.557" Score="5" Body="&lt;p&gt;The reg number's only set in stone once the plane takes off, so you'll only get this information for past flights. Equipment can and often does change between hops on the same flight number, and a multi-stop flight can even arrive at one gate and depart at a different one because of a scheduled plane change (or a last-minute one). The routing/scheduling center for the airline will know the &lt;em&gt;expected&lt;/em&gt; equipment to be used, but that information doesn't technically become public until the flight plan for the hop is filed with the FAA, which for major airlines with pilots and ground staff coordinating each flight, can happen as late as the aircraft taxiing to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can try &lt;a href=&quot;http://www.flightradar24.com/&quot; rel=&quot;nofollow&quot;&gt;http://www.flightradar24.com/&lt;/a&gt;. It's an aviation database of commercial flights updated in real time. &lt;a href=&quot;http://www.flightradar24.com/data/flights/wn3223/&quot; rel=&quot;nofollow&quot;&gt;Here are the most recent stats for Southwest flight WN3223&lt;/a&gt;, a trans-con multi-hop route from NY-Laguardia through Dallas Love, Phoenix, LAX, Oakland and Sea-Tac. There have been a few different tails used for this flight number over the past few days, including N7732A, N746SW and N260WN. This is common for Southwest, as they operate the B737 exclusively, and with very few exceptions any plane in the fleet can handle any route if need be (they did get some new -800s recently which have slightly higher passenger count so they're not &lt;em&gt;completely&lt;/em&gt; interchangeable).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, information on tail numbers is not complete; it should be sufficient to assume the tail doesn't change between stops on the route unless a new one is specified. If you really have to know, the airline can probably tell you what equipment was used on a particular flight if you ask really nicely (or you have some input on possible maintenance issues), but they won't be able to guarantee a particular tail number for an upcoming flight unless the route is such that only one plane in their fleet could do it (which is rare and becoming rarer but still not unheard of).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-06-30T21:21:35.010" LastActivityDate="2015-06-30T21:21:35.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16443" PostTypeId="1" CreationDate="2015-06-30T16:08:33.110" Score="-6" ViewCount="460" Body="&lt;p&gt;2a) How does the APU produce the required starting air supply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) How is the starting air supplied and controlled from the APU to the engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) Describe how the torque from the starter motor is transmitted to the engine rotating assembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;d) Describe the main functions and components of a high energy ignition system.&lt;/p&gt;&#xA;" OwnerUserId="9135" LastEditorUserId="19" LastEditDate="2016-07-28T11:37:16.820" LastActivityDate="2016-07-28T11:37:16.820" Title="How does the start and ignition of aircraft gas tubine engines work?" Tags="&lt;engine-starting&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16444" PostTypeId="1" AcceptedAnswerId="16482" CreationDate="2015-06-30T16:22:42.407" Score="7" ViewCount="4477" Body="&lt;p&gt;The question's kind of broad and simple, so let me be a little more specific. Take Southwest Airlines flight WN3223. This is a multi-stop, trans-continental route that starts at LGA in the morning, flies to DAL, then PHX, LAX, OAK and finally SEA with expected arrival times usually around 10:00 PM. This route runs daily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, according to Flight24, sometimes the same tail number is used for the flight on consecutive days, more often there's a rotation. So the question is, what does the airline normally do with the plane between 10:00 PM one day and 6:00 AM the next (when &lt;em&gt;a&lt;/em&gt; plane, if not &lt;em&gt;the&lt;/em&gt; plane, is expected to be back in the gate at LGA)? Does Southwest just deadhead it all the way back to LGA? Do freight companies subcontract with airlines like Southwest to move boxes overnight on otherwise deadhead flights? Does the plane stay in Sea-Tac and is used for another flight number (possibly the reverse route)? Does the crew deadhead to a maintenance hub? All of the above? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; This question might be similar to the mentioned duplicate but I think it's more specific. I'm asking, more or less, how an aircraft used to operate a route that takes it across the country during daylight hours is typically &quot;reset&quot; so that it can fly that route again. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The assumption, of course, is that the plane does fly that route again on some cyclic schedule, which may itself be wrong; a look at the tail numbers available for WN3223 shows that none of the aircraft used for that route in the past 4 days have flown it again in that same time period, despite the planes used for older flights having ample opportunity to make it back to LGA for another run. So, I think my answer, at least for Southwest's routing model, is &quot;the plane spends the night at SEA, then is sent on a new route number the next day, which may have nothing in common with WN3223 nor get the plane back in a situation to run WN3223 again&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines running non-stop long-hauls probably have a more static schedule; an A380 might fly from Dubai to DFW, then turn around and fly right back, and that one route may be the only thing the plane is scheduled to do for weeks at a time.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="19" LastEditDate="2015-07-01T09:06:45.160" LastActivityDate="2017-09-12T19:13:27.623" Title="What do airlines do with planes at the end of a multi-stop route?" Tags="&lt;airline-operations&gt;&lt;flight-schedules&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16446" PostTypeId="2" ParentId="16437" CreationDate="2015-06-30T16:26:09.020" Score="20" Body="&lt;p&gt;Short answer: It allows them to fly faster and further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: &lt;a href=&quot;https://en.wikipedia.org/wiki/Hapag-Lloyd_Flight_3378&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hapag-Lloyd Flight 3378&lt;/a&gt; demonstrated this impressively on July 12, 2000. Destined for Hannover, they did not retract the gear after take-off in Chania, Crete. The fuel was sufficient for the planned distance plus reserves, but the extended gear increased fuel consumption so much that they ran out of fuel while approaching their diversion airfield near Vienna. Fuel consumption enroute was twice as high as it would had been with the gear retracted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag is composed of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/13957/does-the-downwash-created-by-induced-drag-increase-or-decrease-lift/13978#13978&quot;&gt;lift-related component&lt;/a&gt; (induced drag, blue line below) and a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9285/during-which-part-of-the-flight-the-effect-of-air-resistance-is-more-important/9294#9294&quot;&gt;constant component&lt;/a&gt; (zero-lift drag, red line below), and both depend on the dynamic pressure, which is the product of air density and the square of airspeed. While the lift-related component goes up with reduced dynamic pressure, the constant component will go up with increased dynamic pressure. Thus, extending the gear will increase the constant drag component, and while flying slower helps to reduce its contribution, it will drive up the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529#7529&quot;&gt;lift-related drag component&lt;/a&gt;. In the end, the drag will be higher at all speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IqqyP.png&quot; alt=&quot;Glider drag components&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical drag contributions over speed for a glider. The physics for airliners is the same, only the numbers are bigger. In cruise, all airliners try to fly as close to the minimum drag as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason for a fixed gear are cost, weight and simplicity. Performance will always suffer from it.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-06-30T16:42:43.453" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16447" PostTypeId="1" AcceptedAnswerId="16455" CreationDate="2015-06-30T16:57:32.773" Score="10" ViewCount="2672" Body="&lt;p&gt;Why is it that the rear landing gear of the Caravan is placed so far forward?&#xA;I understand that the center of gravity must lie somewhere in the middle between the nose gear and the  rear gear but wouldn't it be more convenient to have positioned it a little more towards the rear, giving it (to my opinion) more stability? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would avoid the need of placing the support on the the tail of the aircraft when it is parked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/crroi.jpg&quot; alt=&quot;Cessna Caravan on ground.&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image shows clearly the support.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that this would not compromise stability during flight.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="11215" LastEditDate="2017-05-19T13:23:10.117" LastActivityDate="2017-08-26T13:02:17.243" Title="Why is the main landing gear of the Cessna Caravan placed so far forward?" Tags="&lt;landing-gear&gt;&lt;cessna-208&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16449" PostTypeId="1" AcceptedAnswerId="16462" CreationDate="2015-06-30T17:01:49.060" Score="10" ViewCount="1950" Body="&lt;p&gt;I may be wrong but I learned that in regular airliners, pilots always takeoff manually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After taking-off and going to a positive rate of climb:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When do pilots engage the autopilot?&lt;/li&gt;&#xA;&lt;li&gt;Is there a minimum altitude to engage it?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastActivityDate="2015-10-12T10:54:52.073" Title="When do pilots engage the autopilot in airliners?" Tags="&lt;faa-regulations&gt;&lt;airliner&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16450" PostTypeId="2" ParentId="16443" CreationDate="2015-06-30T17:03:22.460" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;2a] how does the APU produce the required starting air supply.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The APU generates pneumatic power using &lt;a href=&quot;https://en.wikipedia.org/wiki/Bleed_air&quot; rel=&quot;nofollow&quot;&gt;bleed air&lt;/a&gt; extracted between the compressor and combustion chamber.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b] how is the starting air supplied and controlled from the APU to the engine&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The starting air is supplied to the engines starters through a network of ducts and valves.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c] describe how the torque from the starter motor is transmitted to the engine rotating assembly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Usually the starter motor turns the accessory gearbox, which rotates the jet engine shaft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;d] describe the main functions and components of a high energy ignition system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An high-energy ignition systems obviously rely on &lt;strong&gt;igniters&lt;/strong&gt; which supply electrical sparks in the combustion chamber for starting or maintaining the air/fuel combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The igniters are powered by &lt;strong&gt;exciters&lt;/strong&gt; generating high-voltage pulses from the aircraft electrical power system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exciters are controlled by the &lt;strong&gt;engine controllers&lt;/strong&gt; according to the position of the &lt;strong&gt;fuel control&lt;/strong&gt; ; &lt;strong&gt;ignition&lt;/strong&gt; and &lt;strong&gt;fire&lt;/strong&gt; switches.&lt;/p&gt;&#xA;" OwnerUserId="9138" LastActivityDate="2015-06-30T17:03:22.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16451" PostTypeId="2" ParentId="16441" CreationDate="2015-06-30T17:10:29.900" Score="8" Body="&lt;p&gt;&lt;em&gt;The step-to-step guide:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;1. Search for Flight Number:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Get hold of the flight number, such as LH123 or AA789 for instance. This is usually found on your ticket, baggage tag or some email.&lt;/li&gt;&#xA;&lt;li&gt;Enter it on a site such as &lt;a href=&quot;http://www.flightradar24.com&quot; rel=&quot;nofollow&quot;&gt;www.flightradar24.com&lt;/a&gt; or &lt;a href=&quot;http://www.planefinder.net&quot; rel=&quot;nofollow&quot;&gt;www.planefinder.net&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Note down the registration (such as N1234A or D-ABYT) for the flight on the day your are interested in.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;2. Search for this Registration:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Try entering it on for instance &lt;a href=&quot;http://www.planespotters.net&quot; rel=&quot;nofollow&quot;&gt;www.planespotters.net&lt;/a&gt; which is often considered a reliable source for aircraft data.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You should be able to get the aircraft history:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First flight and delivery dates (and hence aircraft age)&lt;/li&gt;&#xA;&lt;li&gt;Previous operators and registrations. &lt;/li&gt;&#xA;&lt;li&gt;MSN (manufacturer serial number)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-06-30T22:21:36.440" LastActivityDate="2015-06-30T22:21:36.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16452" PostTypeId="1" AcceptedAnswerId="16456" CreationDate="2015-06-30T17:26:53.977" Score="14" ViewCount="12753" Body="&lt;p&gt;This may be closed as opinionated but I'm looking for answers with hard data if I can get them. The Cessna 172 and Piper Cherokee are touted as two of the most successful light aircraft designs in the world, and they are primary competitors, with Piper originally designing the PA-28 Cherokee to be a lower-cost version of the Comanche that would compete directly with the 172 of the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in today's new market, a 2015 Cessna costs about \$370k, while Piper Archers (the continuation of the PA-28 airframe after Piper's corporate restructure) made in the last 10 years or so are selling for about \$200k. Cessna also seems to hold more value; &quot;classic&quot; 172 airframes from the 70s and 80s hold about a \$100k value in classified ads, while flight-ready Cherokees from the same time can be had for \$30-40k and a few Cherokee airframes are being offered at prices I've only ever seen 150s sold for (though there's likely something wrong with those examples).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft, while different externally (the 172's overhead-wing versus the Cherokee's low-wing design is the biggest difference), seem to have many similar specs on paper; passenger count, horsepower variants (Piper's actually better here as the 180hp variant was most common compared to the standard 172 powerplant at 160hp), instrument capabilities, etc. Cockpit pictures indicate the interiors are comparable; a bit dated as you'd expect from aircraft made 30 years ago, but perfectly serviceable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, where's the additional retained &quot;street value&quot; of the 172 coming from? Is the 172 more well-reputed for safety or reliability? Are its handling characteristics considered better for everyday flight (perhaps due to the parasol wing)? Is this a question of average age of airframes? Is it just the Cessna name (in other words, am I comparing a Toyota Camry to a BMW 5-series)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously some of this stuff will depend on a comparison of specific hulls, but there's a definite trend; the market in general seems to value the 172 more highly than the PA-28 with all other things being equal on paper. The question is why.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="19" LastEditDate="2017-01-24T14:51:20.047" LastActivityDate="2019-12-06T18:49:01.843" Title="What are the major drivers of cost/price differences between Cessna 172 and Piper Cherokee?" Tags="&lt;aircraft-performance&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16453" PostTypeId="1" CreationDate="2015-06-30T18:01:28.533" Score="2" ViewCount="189" Body="&lt;p&gt;Is it common to change out the type of engine during major overhauls of old aircraft?  For example, replacing a 285 hp engine with a 310 hp.  Would this invalidate the performance specifications found in the aircraft's pilots operating manual?&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="1467" LastEditDate="2015-06-30T18:03:43.287" LastActivityDate="2015-07-01T22:15:44.383" Title="Is it common to change the type of engine during major overhauls?" Tags="&lt;aircraft-performance&gt;&lt;general-aviation&gt;&lt;engine&gt;&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16454" PostTypeId="2" ParentId="16447" CreationDate="2015-06-30T18:13:33.343" Score="4" Body="&lt;p&gt;The rear landing gear in a tricycle style plane is placed close to the CG to minimize loads when landing and taking off. When you land an aircraft what you are really doing is transferring the load from the wings to the landing gear. If the CG is directly in line (longitudinally) with the gear, the gear will see the total mass of the aircraft. Any variation from this point will create a moment which will add to the load placed on the gear. Designers strive to minimize this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a similar note when a plane takes off it rotates about the axis of the wheels. Again the father off the CG is from the gear (longitudinally), the more force it may see on rotation (take off).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question directly, the load on an aircraft when its parked on the ground is not a use case designers care about. Its cheaper and (from an engineering stand point) simpler to stick a support under the rear of a parked plane than compromise the gear by moving its location. You should also keep in mind that looks are irrelevant, the engine of an aircraft is heavy and far forward thus it helps to balance out the somewhat empty tail section. For what its worth stability is mathematically calculable and quite quantifiable, it has little to do with looks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know more about aircraft loading (and how its calculated) check out &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/FAA-H-8083-1A.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt; published by the FAA. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-06-30T18:13:33.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16455" PostTypeId="2" ParentId="16447" CreationDate="2015-06-30T18:19:04.850" Score="25" Body="&lt;p&gt;You're right, placing the gear more aft would make ground handling much easier and not affect flight stability. But it would make taking off harder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft has accelerated to a speed just below lift-off speed, the wing's angle of attack is too low to create enough lift when that speed is reached, so the pilot will lift the nose while the main gear is still on the ground. This maneuver is called &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rotation_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;rotation&lt;/a&gt;&quot;, and the speed at which the pilot pulls the stick or yoke back to lift up the nose is called &lt;a href=&quot;https://aviation.stackexchange.com/questions/1251/what-are-the-v-speeds-used-during-a-normal-takeoff-in-a-multi-engine-airplane&quot;&gt;rotation speed&lt;/a&gt;. By the time the aircraft has the right angle of attack, the lift-off speed is reached and the aircraft takes off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the gear is further aft, the downforce on the elevator needed to push the nose up needs to be bigger, and more drag is created during rotation. If the gear is still further aft, the maximum possible downforce at that speed would not be sufficient to get the nose up, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/19214/why-are-the-f-a-18-rudders-deflected-in-opposing-directions-during-takeoff/35867#35867&quot;&gt;rotation must be delayed&lt;/a&gt;. The acceleration up to rotation speed is done with horizontal ground attitude because then the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12892/how-much-lift-do-planes-produce-before-rotation&quot;&gt;wing creates less lift&lt;/a&gt; and also less drag during the take-off run. Therefore, the pilot has to get the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12709/how-does-early-rotation-increase-the-likelihood-of-a-tail-strike-at-take-off&quot;&gt;nose up to get the plane into the air&lt;/a&gt;, or he would need to accelerate to a much higher speed, at which the airplane flies even with its ground attitude. This all helps to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3564/how-is-minimum-runway-length-related-to-v1&quot;&gt;minimize the airfield requirements&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To strike the right compromise between ground handling and elevator downforce during rotation, it is recommended to position the main gear along a line from the center of gravity down to the ground which is slanted 10°-15° back. The drawing below shows limits between 6° and 20°, but this is quite a wide range. Details depend on the desired angle of attack at liftoff and the maximum range of the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ko0A9.jpg&quot; alt=&quot;side view of tricycle gear layout&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side view of the recommended tricycle gear layout (Picture &lt;a href=&quot;http://www.aerospaceweb.org/question/design/q0200.shtml&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-08-26T13:02:17.243" LastActivityDate="2017-08-26T13:02:17.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16456" PostTypeId="2" ParentId="16452" CreationDate="2015-06-30T18:39:45.383" Score="11" Body="&lt;p&gt;There are a lot of factors here but in reality a 172 and a Cherokee are about the same price, lets look the reality.&lt;/p&gt;&#xA;&lt;p&gt;First off a huge chunk of people rent instead of buy. In this regard at the two airports I have been flying out of have both the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;noreferrer&quot;&gt;172s&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;noreferrer&quot;&gt;Cherokees&lt;/a&gt; (both of which I have rented) are the just about the same exact price (all prices in USD).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.doylestownairport.com/Rental-Fleet/Piper-Cherokee-Warrior-N9280A.aspx&quot; rel=&quot;noreferrer&quot;&gt;Cherokee Wet&lt;/a&gt;  : 108&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.doylestownairport.com/Rental-Fleet/Cessna-172-VFR-N92789.aspx&quot; rel=&quot;noreferrer&quot;&gt;VFR Only 172&lt;/a&gt;: 103&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.doylestownairport.com/Rental-Fleet/Cessna-172-IFR-N6086G.aspx&quot; rel=&quot;noreferrer&quot;&gt;IFR 172&lt;/a&gt; : 113&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The used prices (how a lot of people buy planes like this) span the field and I would say are on par (as per my latest perusing of &lt;a href=&quot;http://www.trade-a-plane.com/&quot; rel=&quot;noreferrer&quot;&gt;Trade-A-Plane&lt;/a&gt;). That being said you can get a beat up Cherokee 140 for in and around 20K and a beat up 172 for about the same price (at least from what I have seen listed). At the same time you can get a fully loaded Cherokee 180 or 235 if you go complex with dual GPS/COMS and other toys for the better part of 60-70K, same for the 172s.&lt;/p&gt;&#xA;&lt;p&gt;Yes they are similar planes but the truth is that the price things actually trade hands for is often not disclosed and is almost always not the list price in terms of used stuff. There is a bit of preference as well, if you trained in a Piper you may be more inclined to stay in a Piper and likewise with the Cessnas.&lt;/p&gt;&#xA;&lt;p&gt;As for safety, the &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/1995/December/1/Cessna-172-Safety-Review&quot; rel=&quot;noreferrer&quot;&gt;172 is a very safe plane&lt;/a&gt; by anyone's standards. Then again &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/1994/October/1/PA-28-Safety-Review&quot; rel=&quot;noreferrer&quot;&gt;so is the Cherokee&lt;/a&gt; and it seems that the argument can go on forever but the numbers are the numbers (accidents per 100,000 hours of flight)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The 172: 6.17 overall accident rate.&lt;/p&gt;&#xA;&lt;p&gt;The Cherokee: Cherokees came in at 6.86&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In reality a small difference, but lets be honest they are about on par. For what its worth, the Cherokee numbers include the Arrow which is a retractable and suffers from the proverbial gear up landing as well as other things that make a retractable potentially fail more than a fixed gear plane. This may account for the difference in safety record (again, a very slight difference).&lt;/p&gt;&#xA;&lt;p&gt;While similar on paper there are some mission profiles that allow the planes to serve different roles and may make the 172 more attractive in some cases. The high wing design allows for excellent downward view which makes the 172 a great plane for aerial surveying/photography/pipeline check ups and similar tasks. The 172 also sports two doors compared to the single one on the Cherokee. That being said some feel as though the 172 is a bit easier to get into for the less nimble, but I am young and nimble so I can't speak to this. There are also those who like the high wing design for landing on grass or other back country flying due to the increased ground clearance of the wing allowing you to avoid obstacles.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uQqBS.jpg&quot; alt=&quot;High Wing Ground Clearance&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;From an aircraft family standpoint the Cherokee 235 had a much better useful load than the highest power 172's. However even the 180 Cherokee has a better useful load than the 180 Cessna. When you are flying around a family this is worth considering.&lt;/p&gt;&#xA;&lt;p&gt;Although Cessna had it to an extent, Piper has always had the selling point of &amp;quot;stepping up through the planes&amp;quot;. The idea being that your mission (as time went on) would be to go faster, further, and higher. Subsequently you would need a bigger plane. They facilitated this by delivering a very constant platform in the, &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;noreferrer&quot;&gt;Cherokee&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;noreferrer&quot;&gt;Arrow&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-32&quot; rel=&quot;noreferrer&quot;&gt;Cherokee 6/Lance/Saratoga&lt;/a&gt; then up through twins with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-44_Seminole&quot; rel=&quot;noreferrer&quot;&gt;Seminole&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-34_Seneca&quot; rel=&quot;noreferrer&quot;&gt;Seneca&lt;/a&gt; if you need to go there. While I'm not sure I have ever seen any real data on this, I do have a real world experience with a buddy of mine who has been flying for about 25 years.&lt;/p&gt;&#xA;&lt;p&gt;In response to the question &amp;quot;Have you ever owned any other planes?&amp;quot;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Yeah, I had an Archer for a while, it was a great plane. But then I had a third kid so I bought a Saratoga.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Like it or not the Piper sales model there worked.&lt;/p&gt;&#xA;&lt;p&gt;You could also forgo common sense and just buy a &lt;a href=&quot;https://en.wikipedia.org/wiki/Mooney_M20&quot; rel=&quot;noreferrer&quot;&gt;Mooney&lt;/a&gt; because everyone else put the tail on wrong.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-12-06T18:49:01.843" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16458" PostTypeId="2" ParentId="11658" CreationDate="2015-06-30T19:08:15.267" Score="2" Body="&lt;p&gt;This Info-graphic will answer all your questions&#xA;&lt;img src=&quot;https://i.stack.imgur.com/fQOOg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So basically sit at the back of a Boeing 777 during April or May and avoid Aeroflot.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="9140" LastActivityDate="2015-06-30T19:08:15.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16459" PostTypeId="2" ParentId="16453" CreationDate="2015-06-30T19:30:14.090" Score="4" Body="&lt;p&gt;Not common but not unheard of. Overhauls are the major avenue by which older aircraft variants receive upgrades, effectively becoming newer variants (or functionally equivalent to them). Engine upgrades can be one of the easier changes to make, assuming the new engine was designed to be a &quot;drop-in replacement&quot; (mounts and fuel/electrical connections identical, so you just bolt it on possibly with a token change to the housing). Other changes between variants can be much more in-depth, like stretching the fuselage or altering wing length and profile, which are not typically done to aircraft that have already entered service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In GA, this tends to be more common, as many of the airframes in the GA fleet are decades old (thanks to strict maintenance requirements keeping them serviceable much longer than the expected useful life of a car), and so the benefit of more modern technology of all kinds, including in the engines, tends to justify the costs. Major airlines very rarely do this kind of thing, especially with engines, as jet engines are ridiculously expensive, and when the engine's reached the end of its useful service life, the airframe usually isn't far behind. It's sometimes done to really big, really expensive aircraft like 747s, and the military has done a few &quot;service life extension programs&quot; that involve replacing engines on venerable airframes like B-52s and C-130s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as invalidating ratings, well yes, the original aircraft specs in the POM would no longer apply after an up-engine. The aircraft, as a unit, must be re-rated both theoretically and empirically by an FAA inspector to determine its new specs, and whether all the components of the aircraft can handle them safely (a more powerful engine does not necessarily mean the aircraft can be rated for a higher &quot;do not exceed&quot; speed, if the limiting factor wasn't the engine but the airframe's ability to take the stress). The easiest types of upgrades to get approved are ones that turn the aircraft into a more powerful factory variant of the airframe; for instance, dropping a 235 engine into what used to be a Cherokee 180. With a few other tweaks to bring the entire aircraft up to the specs of a 235, it can be evaluated as if it were one.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-01T22:15:44.383" LastActivityDate="2015-07-01T22:15:44.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16461" PostTypeId="1" AcceptedAnswerId="16463" CreationDate="2015-06-30T20:15:02.337" Score="44" ViewCount="2120" Body="&lt;p&gt;I have noticed a strange visual artifact over the wing of a Boeing yesterday. You can see two manifestations of the artifact in the pictures below.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The first shows it at the front edge of the wing. There were actually many of those, but I only managed to capture one. It looks very similar to a scratch in the window, but moving my head in front of the window didn't move the artifact. So it must have been in a distance somewhere above the wing.&lt;/li&gt;&#xA;&lt;li&gt;The second pictures shows something similar which looked a bit like there was some kind of reflection on the wing, but the sun was on the other side of the plane, so I wasn't sure what caused it. An odd thing was that the stripe moved kind of in sync with the turbulences&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both of those things moved during the flight and were not always on the same position on the wing. Is it possible that those were caused by pressure/density differences of the air or is it just some reflection (or even something totally different)?&#xA;&lt;img src=&quot;https://i.stack.imgur.com/aJG6E.jpg&quot; alt=&quot;first&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/rJqan.jpg&quot; alt=&quot;second&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9143" LastActivityDate="2016-08-28T21:24:57.817" Title="Is the visual artifact seen over the wing from different air densities, a reflection or something else?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16462" PostTypeId="2" ParentId="16449" CreationDate="2015-06-30T20:26:05.200" Score="10" Body="&lt;p&gt;The minimum altitude for autopilot engagement is generally the acceleration height or around 400' AGL though this can vary between operators.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question of &lt;em&gt;when&lt;/em&gt; the autopilot is actually engaged is a more complicated question and is subject to pilot preference.  Personally, I generally hand flew until the first level off or until climbing and accelerating through 10,000 MSL.  Others may turn it on as soon as allowed and most fall somewhere in the spectrum between the two.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-06-30T20:26:05.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16463" PostTypeId="2" ParentId="16461" CreationDate="2015-06-30T20:31:25.763" Score="37" Body="&lt;p&gt;That is the visual effect produced by a shockwave. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air above the wing is accelerated and will reach Mach 1 (the speed of sound) locally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is usually best visible when the sun is right behind you (from the viewers perspective, so on the 3 or 9 o'clock position from the aircraft) and high above the horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a video of &lt;a href=&quot;https://www.youtube.com/watch?v=g4MQqf8wPos&quot; rel=&quot;nofollow noreferrer&quot;&gt;shockwave on an A320 on youtube&lt;/a&gt; (thanks to @&lt;a href=&quot;https://aviation.stackexchange.com/users/3201/mins&quot;&gt;mins&lt;/a&gt; for finding it).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Thanks for sharing those really nice pictures! I have tried to make some in the past but I couldn't make out the shock effect from all the dirt on the window. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-08-28T21:24:57.817" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16464" PostTypeId="1" AcceptedAnswerId="16465" CreationDate="2015-06-30T21:18:25.050" Score="29" ViewCount="8695" Body="&lt;p&gt;Russian cockpits &lt;a href=&quot;https://aviation.stackexchange.com/questions/16434/why-are-russian-cockpit-panels-painted-in-turquoise&quot;&gt;were often painted turquoise to reduce pilot fatigue&lt;/a&gt;. So my question is why most non-Russian cockpits are painted gray, or in the 777's case, tan?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LVbsP.jpg&quot; alt=&quot;777 cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MtDk3.jpg&quot; alt=&quot;a320 cockpit&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="718" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-01T23:36:54.013" Title="Why are most cockpits gray?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16465" PostTypeId="2" ParentId="16464" CreationDate="2015-06-30T22:29:09.247" Score="42" Body="&lt;p&gt;Basically, neutral mid-toned greys or tans are considered to be the best color to use, because they aren't any &lt;em&gt;other&lt;/em&gt; color:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The base color shouldn't be confused for anything in an instrument display. This precludes using red, yellow, green, bright blues or brown, but also black and white as black is used to represent empty space in instrument displays while white is commonly text and also used for other display elements.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The color shouldn't cause glare. Too light a hue will increase sunlight scattering in the cockpit, reducing pilot visibility in high-sunlight situations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The color shouldn't be too dark, as in those same situations a dark color will absorb the sunlight and become hot, increasing ambient temperature of the flight deck, requiring additional cooling system capacity for both pilots and instruments (many civvie aircraft have black instrument panels, but other elements of the design typically prevent the panel catching too much sunlight).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The color has to be relatively easy to find or make, allowing touch-ups. Brighter colors are harder to match exactly; neutral tones blend easier and aren't as distracting even if they are slightly mismatched. This is mainly a military concern, where crew chiefs do what they can with what's on hand; commercial airliners will have hundreds of gallons of their livery colors and other standard touch-ups including cockpit-approved colors available at maintenance hubs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Western thought says the color should be visually uninteresting in order to provide the minimum distraction to the pilot from more important colors in the cockpit. This is where Western and Russian thought primarily differs; Russian designers favored a &quot;mood color&quot; over being completely nondescript, while Western designers favor the background color &quot;disappearing&quot; even if the net effect is depressing to a pilot sitting in it for several hours a day.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To be fair, Western cockpits are not &lt;em&gt;always&lt;/em&gt; grey or tan, but really there are only a couple more common options. European Mirage, Rafale and Gripen fighters are commonly seen with a sky-ish blue interior, providing some of that mood color benefit while remaining nondescript. Aircraft cockpits in WWII, on all sides, were painted in whatever the crew chief had available, which usually amounted to land-based planes getting the same olive drab that coated every piece of metal the Army owned, while naval variants got one of the various blue-grays used on the ship itself.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-01T23:36:54.013" LastActivityDate="2015-07-01T23:36:54.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16466" PostTypeId="1" CreationDate="2015-06-30T23:18:15.820" Score="7" ViewCount="2156" Body="&lt;p&gt;I just finished reading &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;this article&lt;/a&gt; and couldn't understand why in 3 minutes and 30 seconds even though there was no reliable speed data, pilot could not level the plane? Isn't the angle of attack reported by a gravity based tool like in off-road vehicles?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summed up Question: When it's unclear what is happening with the aircraft, isn't it safer to put it in level position and medium speed? (Sorry for rudimentry language here)&lt;/p&gt;&#xA;" OwnerUserId="9146" LastEditorUserId="19" LastEditDate="2015-10-31T14:23:46.760" LastActivityDate="2015-10-31T14:23:46.760" Title="Why Air France 447 could not reduce angle of attack?" Tags="&lt;angle-of-attack&gt;&lt;af447-accident&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16468" PostTypeId="1" CreationDate="2015-07-01T00:52:44.890" Score="4" ViewCount="855" Body="&lt;p&gt;Basically, if the cabin in a large air liner is depressurized, are pilots protected in any way, specifically:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the cockpit separately pressurized from the rest of the cabin?&lt;/li&gt;&#xA;&lt;li&gt;Can they keep consciousness if sudden depressurization happens?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2015-07-01T02:24:29.667" Title="If commercial airliner cabin is depressurized, are pilots protected against it in any ways?" Tags="&lt;cockpit&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16469" PostTypeId="2" ParentId="16468" CreationDate="2015-07-01T01:15:43.573" Score="7" Body="&lt;p&gt;No, the cockpit is not separately pressurized. That would be impractical and not particularly useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, pilots do have oxygen masks, just like the passengers. Unlike the passenger masks, these masks are generally designed to be donned extremely quickly, with one hand (they tend to have automatic straps that clamp on without needing to be manually adjusted). The masks also have a separate oxygen supply from the passenger masks, and have much more oxygen available for each mask, and have other nice features. Furthermore, when one pilot is off the flight deck, the other wears an oxygen mask that's either releasing oxygen or set to automatically do that if the plane depressurizes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If sudden depressurization happens, there are still a few seconds of useful consciousness for most people. That time is enough for airline pilots to put on their masks. Once the crew has on oxygen masks, they can control the depressurized plane just fine (depending on how it depressurized, of course: if the tail broke off, there's not much that can really be done).&lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-07-01T01:15:43.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16470" PostTypeId="2" ParentId="16468" CreationDate="2015-07-01T02:24:29.667" Score="5" Body="&lt;p&gt;The cockpit crew have their own oxygen bottle that supplies only their masks with plenty of capacity to handle a depressurization or smoke event to landing.  The masks are quick-don and can supply 100% O2 at positive pressure.  This means you can put them on with one hand with a very quick maneuver (grab to pull out of its stowed position which inflates tubing that you put over your head which compress when you let go of the mask) and they can provide breathable air even if ambient partial pressure of oxygen would be too low to breathe.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-07-01T02:24:29.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16471" PostTypeId="1" AcceptedAnswerId="16497" CreationDate="2015-07-01T02:52:27.053" Score="7" ViewCount="1013" Body="&lt;p&gt;Before anything I know this can be sound something stupid and obvious, but I swear I lost 3 or 4 hours searching images and videos before posting this question. So please be mercy with my poor knowledge.&lt;/p&gt;&#xA;&lt;p&gt;I'm looking for a view of the rear side of the cockpit (when the door is, and the third and four ocuppant seat is).&lt;/p&gt;&#xA;&lt;p&gt;I only get a very partial views, and the more detailed image is a diagram from the cockpit deck layout (the following is an example from A330, I could get the A340, but I'm not looking for a diagram):&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zv2hz.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;Everyone knows the typical eye-lens shot of the panel, but it was impressive to me that get one of the rear view is really difficult, more even after the tragedy of the Germanian, where a lot of shots has no relevance with I'm looking for.&lt;/p&gt;&#xA;&lt;p&gt;Any help will be preciated.&lt;/p&gt;&#xA;&lt;p&gt;Thanks in advance.&lt;/p&gt;&#xA;" OwnerUserId="8985" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-04-14T13:04:11.200" Title="How is the cockpit rear view of an Airbus A340?" Tags="&lt;airbus&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16472" PostTypeId="2" ParentId="16233" CreationDate="2015-07-01T04:05:15.787" Score="3" Body="&lt;p&gt;I have worked on large and small aircraft.  You will find a 400hz power bus only on large aircraft. The reason is the greater quantity of poles in the generator and hence weight. Smaller aircraft use a 28v DC system for the avionics.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2015-07-01T04:05:15.787" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16473" PostTypeId="2" ParentId="16377" CreationDate="2015-07-01T05:10:45.297" Score="3" Body="&lt;p&gt;Sadly, the SR-71 (my favorite) would be an easy target these days. &#xA;The IR heat signature from the engines and nacelles make it readily visible. &#xA;In addition to the amazing information regarding missles from the posters above, &#xA;there are distant horizon laser tracking systems and chemical lasers which can take down any aircraft (the USAF ABL system).  There are also some newer ground-based fiber lasers which can do damage to composites on both missles and aircraft at long range.&lt;/p&gt;&#xA;" OwnerUserId="9150" LastEditorUserId="9150" LastEditDate="2015-07-01T15:30:31.620" LastActivityDate="2015-07-01T15:30:31.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16474" PostTypeId="2" ParentId="16427" CreationDate="2015-07-01T05:15:25.597" Score="4" Body="&lt;p&gt;To simplify, the differences are similar to comparing a dart to a glider -- it all gets back to the wings.&#xA;The delta wing provides the best overall flight characteristics in terms of lift and control surface efficiency.  A delta wing will allow you to come in low and slow and in control, but is that always what you need if you are flying a fighter jet? &#xA;The aerodynamics of fighter jets are designed to provide lift, stability, and control at a much wider angle of attack.  Comparing the wing characteristics between the two planes in a wind tunnel, notice how the wing thickness (airfoil) of the fighter plane is much less (relatively flat) at the leading edge.&lt;br&gt;&#xA;Although the fighter plane provides less lift at the same angle of attack and requires a faster airspeed to stay aloft without stalling, the control over a wider range of airspeeds is worth the tradeoff for the fighter jet performance and maneuverability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shut down a fighter plane engine, and it will drop like a yard dart.  The intake on a fighter plane is designed to receive as much air as possible, and will cause turbulence at the inlet if the blades are not turning fast enough.  There simply is a minimum speed range to keep the plane in flight and under control as it is coming in for a landing.&lt;br&gt;&#xA;The power to weight issue has a downside -- the fighter plane is less efficient in fuel consumption -- it is even less efficient if the inlet has nacelles or ducting to mask a thermal signature.&lt;br&gt;&#xA;The power to weight ratio of the fighter plane is much higher than a commercial aircraft, and the answers above from the other posters regarding thrust cover the topic well. &#xA;The best fighter jets provide the most maneuverability over the widest range of speeds.&lt;br&gt;&#xA;Both types of aircraft would technically benefit from a lower landing (and stalling) speed, but in both cases, other flight characteristics are a higher priority.  &lt;/p&gt;&#xA;" OwnerUserId="9150" LastActivityDate="2015-07-01T05:15:25.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16475" PostTypeId="2" ParentId="16466" CreationDate="2015-07-01T07:19:01.390" Score="3" Body="&lt;p&gt;Something I've seen written but not discussed on many of these internet discussions, is the how the stall warning sound worked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently the stall warning sounded, but &lt;em&gt;stopped&lt;/em&gt; again as the plane went to &lt;em&gt;higher&lt;/em&gt; angles of attack.  (This might be a deliberate behaviour, to prevent false warning sounds when operating on the ground in wind.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot lowered the angle of attack, suddenly the stall sound &lt;em&gt;started&lt;/em&gt; again.  One of the pilots may have heard this and instinctively pulled up again to clear the sound.  The angle was kept (very) high for the rest of the flight...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I'd say the pilots had at least some reason for genuine confusion in this matter.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-07-01T07:19:01.390" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16476" PostTypeId="1" CreationDate="2015-07-01T07:37:55.333" Score="14" ViewCount="9355" Body="&lt;p&gt;I really like the 737, it is perhaps my favorite airliner. One curiosity of this aircraft (afaik, it is the only commercial airliner) is that the main landing gear has no cover:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5zaNO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is another picture from the inside:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/fAxak.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this situation, how does the aircraft protect the gear mechanism from weather/freezing?&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="19" LastEditDate="2017-01-09T10:46:14.620" LastActivityDate="2017-01-09T10:46:14.620" Title="How is the 737 main landing gear protected from weather?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;&lt;boeing-737&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16477" PostTypeId="2" ParentId="12054" CreationDate="2015-07-01T07:42:59.270" Score="4" Body="&lt;p&gt;Well, the SDR dongle paid off - mystery solved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It turns out, the signal was actually at 153.2MHz, but was somehow breaking through into 110.515MHz on my handheld scanner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The signal originates from a high power pager transmitter using the FLEX protocol. As this is plain text, I decoded some of it using an excellent open source application called PDW, and have listed it below for reference and general interest (sensitive information has been redacted!).&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;  0074162  23:12:31 30-06-15 FLEX-A    ALPHA   3200   31:Jun 30 23:11 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:10:49&#xA;  0000002  23:12:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0069&#xA;  0121518  23:12:59 30-06-15 FLEX-A    StNUM   3200   31948    &#xA;  1734139  23:13:01 30-06-15 FLEX-A    ALPHA   3200   61:Jun 30 23:12 Term B  Page-fail test&#xA;  1756286  23:13:24 30-06-15 FLEX-A    ALPHA   3200   PIN 6840 PLS CALL DSCC ON 08457 500***&#xA;  0118459  23:13:46 30-06-15 FLEX-A    ALPHA   3200   20150630 23:13 boc1web02.servstream.com: conn CRITICAL ALERT&#xA;  0000002  23:14:03 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0070&#xA;  1734139  23:14:09 30-06-15 FLEX-A    ALPHA   3200   62:Jun 30 23:13 Term B  Page-fail test&#xA;  0076963  23:14:29 30-06-15 FLEX-A    ALPHA   3200   55:Jun 30 23:13 23.13hrs Zone 14 L550 down 15 Mins maint in attendance FROM: GB50-AFENNEL3&#xA;  0074162  23:14:46 30-06-15 FLEX-A    ALPHA   3200   32:Jun 30 23:13 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:12:42&#xA;  0074179  23:14:48 30-06-15 FLEX-A    ALPHA   3200   19:Jun 30 23:13 Z2A LH Stn 200  Main Call 30-JUN-2015 23:13:22&#xA;  0074194  23:14:50 30-06-15 FLEX-A    ALPHA   3200   56:Jun 30 23:13 23.13hrs Zone 14 L550 down 15 Mins maint in attendance FROM: GB50-AFENNEL3 FROM: GB50-AFENNEL3&#xA;  0107291  23:14:50 30-06-15 FLEX-A    StNUM   3200   2422085  &#xA;  0074076  23:14:50 30-06-15 FLEX-A    ALPHA   3200   60:Jun 30 23:13 Fac 1670 More than 20 I/P on conv 30-JUN-2015 23:11:30&#xA;  0086317  23:14:52 30-06-15 FLEX-A    ALPHA   3200   36:Jun 30 23:13 Dodo Panel 23 Entry Movement Alarm 000065 30-JUN-2015 23:12:03&#xA;  0000002  23:14:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0071&#xA;  0067432  23:14:59 30-06-15 FLEX-A    ALPHA   3200   71:Jun 30 23:14 Water Test WATER TEST SUMP LEVEL HIGH 001215 30-JUN-2015 23:14:46&#xA;  1754937  23:15:16 30-06-15 FLEX-A    ALPHA   3200   'Adv' 7440298 30/06/2015 23:08:33 tight chest, struggling to breathe, EMAS ETA 11 mn, Priority RED2 Age 59 Incident area - KETTERING ** ****** ** NN16 ***&#xA;  0067432  23:15:22 30-06-15 FLEX-A    ALPHA   3200   72:Jun 30 23:14 Skid RETURN PROBLEM CHECK SKID RETURN Tested o.k. 30-JUN-2015 23:12:25&#xA;  1734139  23:15:24 30-06-15 FLEX-A    ALPHA   3200   63:Jun 30 23:14 Term B  Page-fail test&#xA;  0086317  23:15:44 30-06-15 FLEX-A    ALPHA   3200   39:Jun 30 23:14 Dodo Panel 6 P&amp;amp;F Emergency Stop relay 125KN1 - 400301.08 30-JUN-2015 23:13:32&#xA;  1734136  23:15:46 30-06-15 FLEX-A    ALPHA   3200   19:Jun 30 23:14 Term A  Page-fail test&#xA;  0067154  23:15:50 30-06-15 FLEX-A    ALPHA   3200   Fr:nocteam Su:Escalate PQV-73575-125 Tx:Auto escalation of ticket (3 hour rule) Ticket: PQV-73575-125 Queue: VelociX Date raised: 2015-06-30 20:11:27 Subject: ANTEL New asset request&#xA; 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 0200905  23:22:34 30-06-15 POCSAG-3  ALPHA   1200   23:22-98 30/06/2015 23:20:18 INC 14517787 31C02 ************, ELLESMERE PORT, CH65 *** Male 64 Years M PASSING OUT GRD&#xA;                                                      340506 375692&#xA;  0334410  23:23:50 30-06-15 POCSAG-3  ALPHA    512   23:22-41 C2 Incident Allocated, Locn: *****, GREENACRES CARE CENTRE, TEARN ROAD, PL35JF, , AZ:, CAD:300615005110, ChComp:&#xA;  1508907  23:23:51 30-06-15 POCSAG-4  ALPHA    512   CH3A 512&#xA;  0273040  23:24:04 30-06-15 POCSAG-4  ALPHA   1200   30/06/2015 CH3A&#xA;  0269168  23:24:20 30-06-15 POCSAG-3  ALPHA   1200   23:24-10 30/06/2015 23:22:15 INC 14517792 10D02 ***********, NEWBOLD ROCHDALE ROCHDALE, OL16 *** Female 24 Years&#xA;                                                      MIGRAINE - FEELS SICK GRD 390789 412576&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="7000" LastActivityDate="2015-07-01T07:42:59.270" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16479" PostTypeId="2" ParentId="16466" CreationDate="2015-07-01T08:33:20.957" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I just finished reading this article and couldn't understand why in 3&#xA;  minutes and 30 seconds even though there was no reliable speed data,&#xA;  pilot could not level the plane?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you look at &lt;a href=&quot;https://www.youtube.com/watch?v=n-hbWO0gL6g&quot;&gt;this video&lt;/a&gt; by the French accident investigation bureau (BEA) you can see what happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem started when the speed indicators failed temporarily because of icing of the pitot tubes. The aircraft was flying through the intertropical convergence zone (ITCS) where severe thunderstorm activity can build up to high altitudes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of maintaining attitude and thrust setting, which is a normal procedure when speed indication is lost, the pilot flying (PF) brought the nose up. The aircraft started to climb but at the same time lost a lot of speed (trading kinetic energy for potential energy). Eventually the airspeed dropped so far that the aircraft stalled. By the time the aircraft entered the stall, the pitot tubes where de-iced and all speed indicators were working again. From the moment the aircraft stalled it started to sink. The PF tried to maintain a nose-up attitude, eventually using full aft stick. We can only guess to the reason why; it is likely that he was disoriented and had no confidence in the instruments after the failure. Yet it goes against basic flying instincts to pull the nose up in a stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is naturally stable and will automatically drop its nose in case of a stall so it took some effort by the PF to keep the nose up. The horizontal tailplane then stalled as well which removed a lot of the nose-down tendency. The result was that the aircraft was in a nose-up attitude for the most part of the descent.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angle of attack remained therefore too high and the aerodynamic stall persisted all the way down. If the crew would have brought the nose down they would have increased the speed, lowered the angle of attack and recovered from the stall. Once recovered from stall they could then level off the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may have contributed to the confusion of the crew that the airspeed was below 60 knots during portions of the descent. As they accelerated through 60 knots, the stall warning re-appeared. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall indicator systems makes use of alpha vanes which need some airflow over them to work. By inhibiting the stall warning below 60 knots the system is prevent from giving nuisance warnings on the ground. Such a speed is not normally encountered during flight, even not during a stall.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another contribution to the accident may be that the pilot-not-flying (PNF) cannot see what stick inputs are given by the pilot flying. If it would have been in a different aircraft with coupled yokes, the PNF may have realized what was going on. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Isn't the angle of attack reported by a gravity based tool like in&#xA;  off-road vehicles?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The angle of attack is the angle between the chord of the wing and the incoming airflow. It is not related to gravity. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Summed up Question: When it's unclear what is happening with the&#xA;  aircraft, isn't it safer to put it in level position and medium speed?&#xA;  (Sorry for rudimentry language here)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Initially only the speed indicator failed. If the crew would have remained at the same attitude and power setting the aircraft would not have stalled. That is the standard procedure in such a case (&quot;thrust and attitude&quot;)  That may not have been the proper reaction in this case. The aircraft was encountering severe turbulence and the fastest way out may have been to climb. But after the stall warning sounded all speed indicators were back to normal and the aircraft was flyable. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-07-01T08:33:20.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16480" PostTypeId="1" CreationDate="2015-07-01T08:55:06.843" Score="6" ViewCount="545" Body="&lt;p&gt;Is there any authoritative source from where we can find out the number of commercial jets that a country or airline purchases annually?&lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="1696" LastEditDate="2016-07-05T19:26:17.383" LastActivityDate="2016-07-05T19:26:17.383" Title="Where can I find the number of commercial jets that a country or airline purchases annually?" Tags="&lt;commercial-aviation&gt;&lt;aircraft-purchase&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16481" PostTypeId="2" ParentId="16476" CreationDate="2015-07-01T09:00:35.593" Score="9" Body="&lt;p&gt;Aircraft icing is not caused by ice in clouds- it is formed by supercooled water droplets (&lt;a href=&quot;http://www.crh.noaa.gov/Image/lmk/Brian%20S/LMK_Icing_Show.pdf&quot;&gt;Source&lt;/a&gt;). They freeze on impact with a surface that has some location with zero flow velocity, most often on the leading edge of the wing.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ice accumulates on every exposed frontal surface of the aeroplane – not just on the wings, propeller, and windshield, but also on the antennas, vents, intakes, and cowlings. It builds in flight where no heat or boots can reach it. It can cause antennas to vibrate so severely that they break. In moderate to severe conditions, a light aircraft can become so iced up that continued flight is impossible. The aeroplane may stall at much higher speeds and lower angles of attack than normal. It can roll or pitch uncontrollably, and recovery may be impossible. &lt;a href=&quot;http://www.caa.govt.nz/safety_info/gaps/aircraft_icing_handbook.pdf&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The gear as such as is not worse off than normal landing gear. The B737 has wheel caps visible in your first photo to cover towards the outside, and is not allowed to fly without them. If icing had been a problem, the same concern would extend onto landing gear doors being frozen shut. Landing gears bays are unpressurised and very cold normally anyways.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-01T09:24:26.497" LastActivityDate="2015-07-01T09:24:26.497" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16482" PostTypeId="2" ParentId="16444" CreationDate="2015-07-01T09:45:31.783" Score="8" Body="&lt;p&gt;Deadheading is rarely done because it is a non-revenue movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most common use of deadheading (that is, flying the aircraft empty) is done for maintenance runs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the end of a scheduled route, the plane is parked at the last destination.  Sometimes, the next flight around uses the plane (if the route can be serviced by the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, airlines try to &quot;park&quot; their planes at their hub locations (where they have favorable landing and parking fees) rather than leave the aircraft at another airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight operations and planning make sure the aircrafts are maximized on revenue movements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give you an example - the shortest scheduled commercial flight for the A380 is Dubai - Kuwait (&lt;a href=&quot;http://flightaware.com/live/fligh6t/UAE857&quot;&gt;EK857&lt;/a&gt;); and the return flight Kuwait - Dubai (&lt;a href=&quot;http://flightaware.com/live/fligh6t/UAE858&quot;&gt;EK858&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inbound aircraft on the flight yesterday (A6-EOH) was inbound from Perth to Dubai; and then flew to Kuwait and then back to Dubai. The next day (July 1st), the same aircraft is scheduled for SFO. (See the &lt;a href=&quot;http://www.flightradar24.com/reg/a6-eoh&quot;&gt;flight log at flightradar24&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2015-07-01T09:45:31.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16483" PostTypeId="2" ParentId="16444" CreationDate="2015-07-01T10:46:46.437" Score="7" Body="&lt;p&gt;The assumption that certain aircraft remain on certain routes is wrong. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines try to spread the individual 737 amongst all 737 routes operated by the airline. Primarily this is due to maintenance. If a particular aircraft flew lots of short routes all the time, it would need maintenance a lot quicker than another 737 that stuck to the longer flights (because most maintenance is based on flight cycles, not flight hours). This can create headaches for the maintenance schedulers, which can be avoided if all aircraft in the fleet fly roughly the same amount of cycles per month. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically, it is very likely that the aircraft would sit overnight in Seattle, possibly undergoing some minor maintenance, before flying out to any destination in the morning, unrelated to the previous leg.  &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-07-01T10:46:46.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16484" PostTypeId="1" AcceptedAnswerId="53800" CreationDate="2015-07-01T10:59:57.670" Score="5" ViewCount="1143" Body="&lt;p&gt;If an airliner (enroute via IFR rules) discovers a thunderstorm ahead, how much lateral deviation is allowed before a clearance from ATC needs to be obtained ?&#xA;Is the width of an RNAV corridor only for navigation errors or also for intended deviations ?&lt;/p&gt;&#xA;" OwnerUserId="3964" LastEditorUserId="1696" LastEditDate="2016-06-14T16:53:46.663" LastActivityDate="2018-07-25T18:43:58.920" Title="What is the maximum lateral deviation allowed on an RNAV route?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-path&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16485" PostTypeId="2" ParentId="16381" CreationDate="2015-07-01T11:21:21.737" Score="2" Body="&lt;p&gt;An Apache AH-64 has a rotor that's about 100x times the diameter, so the swept area is 10000x larger. It can lift around 10000 kg, which means your ducted fan would lift about 1 kg. You'd need 2 fans with approximately one meter diameter.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-07-01T11:21:21.737" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16486" PostTypeId="2" ParentId="16484" CreationDate="2015-07-01T11:40:13.097" Score="2" Body="&lt;p&gt;If the aircraft is under ATC control then no deviation is allowed except in an emergency. A pilot who wants a course change would need to request it from ATC and obtain a clearance. If the flight is not under ATC control and wants to divert then it's pilot's discretion, he/she would notify ATC of the change if receiving some sort of service. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-07-01T11:40:13.097" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16487" PostTypeId="1" AcceptedAnswerId="16492" CreationDate="2015-07-01T13:30:14.763" Score="4" ViewCount="8157" Body="&lt;p&gt;We have several spectacular and amazing &lt;a href=&quot;https://www.youtube.com/results?search_query=airplane%20in%20sky&quot; rel=&quot;nofollow&quot;&gt;videos&lt;/a&gt; of aircraft, flying high in the sky.  How are these videos filmed, at great altitudes?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-07-01T15:26:32.240" Title="How are aircraft filmed in sky?" Tags="&lt;aircraft-operations&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16488" PostTypeId="1" AcceptedAnswerId="16493" CreationDate="2015-07-01T13:38:57.737" Score="8" ViewCount="5656" Body="&lt;p&gt;I received a document where it it specified that the flight relevant for such document can only take place in &quot;Day VFR&quot; conditions undear EASA regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this connected to VMC? What does EASA defines as &quot;Day VFR&quot;?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2020-09-17T12:14:57.867" Title="What is defined as &quot;day VFR&quot; under EASA rules?" Tags="&lt;easa-regulations&gt;&lt;visual-flight-rules&gt;&lt;vmc&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16489" PostTypeId="2" ParentId="16487" CreationDate="2015-07-01T14:03:49.217" Score="5" Body="&lt;p&gt;I film all &lt;a href=&quot;https://www.youtube.com/watch?v=mqNlFbviMwA&quot; rel=&quot;noreferrer&quot;&gt;my stuff&lt;/a&gt; (from inside the plane) with a &lt;a href=&quot;http://shop.gopro.com/cameras?gclid=Cj0KEQjwn86sBRDroPiR0LrSzNYBEiQAzOaSYAjuwIfECB_OCFMdidWLegB7BJOCO-IuWApZG06wjOsaAj8d8P8HAQ&quot; rel=&quot;noreferrer&quot;&gt;GoPro&lt;/a&gt;. This seems to be the common way the smaller guys are doing it. There are companies that make mounts that will even hold the camera on &lt;a href=&quot;http://www.rammount.com/reviews/goprohdmountedairplane&quot; rel=&quot;noreferrer&quot;&gt;outside a plane&lt;/a&gt;. You can check out &lt;a href=&quot;http://sportys.tumblr.com/post/42926333172/gopro-quick-start-guide-for-pilots&quot; rel=&quot;noreferrer&quot;&gt;this post&lt;/a&gt; from Sporty's on the matter.  Some of the stuff shot by the pros may be taken from another plane or a helicopter. The news choppers I see leaving from KPNE have the newer nose style cameras that I assume they operate from the inside of the chopper. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wwDrb.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-01T14:03:49.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16490" PostTypeId="2" ParentId="16487" CreationDate="2015-07-01T14:43:56.627" Score="0" Body="&lt;p&gt;You are not specific in your question, so there are many ways that aerial footage can be captured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/16489/1696&quot;&gt;As Dave mentions&lt;/a&gt;, GoPro cameras have gained popularity especially with private pilots. They are relatively cheap, small, easy to use, and capture good quality video. Many videos from &lt;a href=&quot;https://youtu.be/8aoXSE5mUHw&quot; rel=&quot;nofollow noreferrer&quot;&gt;inside the cockpit&lt;/a&gt; or &lt;a href=&quot;https://youtu.be/6Du513WwUmg&quot; rel=&quot;nofollow noreferrer&quot;&gt;outside&lt;/a&gt; use cameras like these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air to air footage is taken from other aircraft. For the most flexibility, a &lt;a href=&quot;https://youtu.be/ky67166frag&quot; rel=&quot;nofollow noreferrer&quot;&gt;fighter jet&lt;/a&gt; is a &lt;a href=&quot;http://www.imaging-resource.com/news/2014/07/10/dream-job-being-the-official-photographer-of-the-us-air-force-thunderbirds&quot; rel=&quot;nofollow noreferrer&quot;&gt;good choice&lt;/a&gt;. You could also shoot through the door of a &lt;a href=&quot;https://youtu.be/Hcy37lmQpg0&quot; rel=&quot;nofollow noreferrer&quot;&gt;smaller aircraft&lt;/a&gt;. Helicopters are best at lower altitudes and speeds but are good for filming &lt;a href=&quot;https://youtu.be/gI4jWYZLeHQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;takeoffs and landings&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-01T15:04:50.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16491" PostTypeId="2" ParentId="16437" CreationDate="2015-07-01T14:53:33.280" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why do all the airplanes have to retract their landing gear, once they reach some specific height?&lt;br&gt;&#xA;  Why can't they simply leave their landing gear deployed all through the flight?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Both questions are false on their premise:&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;All airplanes do not have to retract their gear;  many planes are fixed-gear, and &lt;strong&gt;&lt;em&gt;cannot&lt;/em&gt;&lt;/strong&gt; retract gear.  &lt;em&gt;Some&lt;/em&gt; planes retract their gear.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Planes can leave their gear deployed all through flight, provided they remain slow enough that the extra airflow drag doesn't damage the airplane and landing gear.   &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Planes that have retractable gear generally retract their gear for improved performance.  Not having wheels and struts hanging down streamlines the plane, improves fuel efficiency, enables them to fly faster and higher, and makes for a quieter, more comfortable ride inside the cabin.  So, retracting gear is generally desirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, as your question suggested, it is not required, and it is not based on a specific height.  (if anything, it is based on an airspeed)&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-07-01T14:53:33.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16492" PostTypeId="2" ParentId="16487" CreationDate="2015-07-01T15:02:47.827" Score="10" Body="&lt;p&gt;Two words: chase planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few more words: The easiest way to film an airplane in flight is with another airplane in flight. &lt;a href=&quot;http://www.airlinereporter.com/2012/09/chasing-lans-boeing-787-dreamliner-with-aeroial-photographers-of-wolfe-air/&quot; rel=&quot;noreferrer&quot;&gt;Here's one article on how that's done&lt;/a&gt;, including images captured from both sides; the chase plane (a Learjet 25B) getting the shots of the 787 Dreamliner, and crew aboard the Dreamliner getting a few snapshots of the chase plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9VLG9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/O9r0n.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early shots taken from chase planes often used simple handheld cameras; a two-seater would normally be used with the pilot in front and the photographer in back. This is still a totally viable way to do it, but more modern professional shoots utilize aircraft specifically modified for the task by adding internal or external camera mounts, optical-quality viewports, etc. Here's a modified T-33 used by Boeing specifically for air-to-air photography, including some of the initial publicity shots of the 787 in flight; notice the camera mount between the seats that can be used by the GIB (he's using a handheld in this photo:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8W1Iw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For lower-speed shots, you can also use a helicopter. Many of these such as news choppers have remote-control cameras on gyro-stabilized mounts, so the vibration of the airframe is minimized in the shot even at high zoom:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/E5nog.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These same camera systems can be used for air-to-air shots as well, however the maximum airspeed of the helicopter becomes a limiting factor. Still great for publicity shots of small prop planes, or takeoffs/landings.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-01T15:26:32.240" LastActivityDate="2015-07-01T15:26:32.240" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16493" PostTypeId="2" ParentId="16488" CreationDate="2015-07-01T15:21:21.653" Score="9" Body="&lt;p&gt;It's by opposition to &lt;a href=&quot;https://en.wikipedia.org/wiki/Night_VFR&quot; rel=&quot;nofollow noreferrer&quot;&gt;Night VFR&lt;/a&gt; (NVFR) which allows to fly by night in visual meteorological conditions. So the answer will focus on NVFR, rather than on &lt;em&gt;day VFR&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EASA harmonization over EU countries is done by enforcing Standardised European Rules of the Air (&lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2012:281:0001:0066:EN:PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;SERA&lt;/a&gt;). SERA states that a night flight must be conducted in IFR, and therefore the crew must hold an Instrument Rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prior to SERA, some countries did not allow VFR at night for security reasons (aircraft not visually identifiable, and no transponder), but other did, that's the case for the UK that I'll use as an example here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When implementing SERA, EU countries can use &lt;em&gt;acceptable means of compliance&lt;/em&gt;, as described in &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/ED%20Decision%202013-013-R.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ED Decision 2013/013/R&lt;/a&gt; and &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/Annex%20to%20ED%20Decision%202013-013-R.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;its annex&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;NVFR is implemented (or denied) in EU country by country. So rules may differ between countries. UK example:&lt;br&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=2685&amp;amp;pagetype=65&amp;amp;appid=54&amp;amp;mode=detail&amp;amp;appproc=32&quot; rel=&quot;nofollow noreferrer&quot;&gt;UK license can be extended&lt;/a&gt; for NVFR.&lt;/li&gt;&#xA;&lt;li&gt;More for UK NVFR: &lt;a href=&quot;https://www.caa.co.uk/docs/33/SafetyNotice2012007.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Safety Notice: SN-2012/007&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;In practice, VFR at night is permitted in accordance with SERA requirements. Aircraft leaving the vicinity of an aerodrome must maintain 2-way communication with ATC and file a flight plan. The process of 'booking out' is still accepted as an alternative method to filing a formal paper or electronic flight plan in certain circumstances. Similarly, abbreviated flight plans filed in flight are still permitted. There are also more restricting weather minima:&lt;br&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Minimum cloud ceiling of 1500 ft AMSL&lt;/li&gt;&#xA;&lt;li&gt;Flight visibility of 5 km, or 3 km in the case of a helicopter flying outside controlled airspace&lt;/li&gt;&#xA;&lt;li&gt;Maintain sight of the surface when flying at 3,000 ft AMSL or below&lt;/li&gt;&#xA;&lt;li&gt;Minimum height of 1000 ft (or 2000 ft if over high terrain) above the highest fixed obstacle within 8 km of the aircraft except when taking off or landing &#xA;&lt;br&gt;&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Night is defined for  this purpose:&lt;br&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;e.g. for UK in &lt;a href=&quot;http://www.legislation.gov.uk/uksi/2009/3015/contents/made&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Navigation Order 2009 Art. 255&lt;/a&gt;:&lt;br&gt;&lt;br&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;'Night' means the time from half an hour after sunset until half an&#xA;  hour before sunrise [...] at surface level.&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Aircraft must be compliant for NVFR, e.g. this equipment is required:&lt;br&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;artificial horizon&lt;/li&gt;&#xA;&lt;li&gt;Instrument Lighting&lt;/li&gt;&#xA;&lt;li&gt;Landing Light&lt;/li&gt;&#xA;&lt;li&gt;Position and Anti Collision Lights&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In countries where NVFR is not allowed, IFR applies at night.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="1467" LastEditDate="2018-04-10T12:03:52.717" LastActivityDate="2018-04-10T12:03:52.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16494" PostTypeId="2" ParentId="16480" CreationDate="2015-07-01T16:52:44.857" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://www.planespotters.net/&quot; rel=&quot;nofollow&quot;&gt;planespotters.net&lt;/a&gt; lists, for many commercial airlines, all their airplanes along with their delivery dates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for an &lt;em&gt;authoritative source&lt;/em&gt;, you would have to look at the IATA or any other paying site such as airfleets.net.&lt;/p&gt;&#xA;" OwnerUserId="9138" LastActivityDate="2015-07-01T16:52:44.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16495" PostTypeId="1" CreationDate="2015-07-01T17:07:39.327" Score="30" ViewCount="48911" Body="&lt;p&gt;If the 747 can fly with two engines, why does it have four engines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is gained by adding another 2 engines?&#xA;Flights over the ocean?&#xA;Fuel savings?&#xA;Safety?&lt;/p&gt;&#xA;" OwnerUserId="6967" LastEditorUserId="1696" LastEditDate="2015-07-01T19:38:23.010" LastActivityDate="2020-01-31T00:18:11.870" Title="Why does the 747 have 4 engines instead of 2?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;boeing-747&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16496" PostTypeId="2" ParentId="16495" CreationDate="2015-07-01T17:22:01.690" Score="36" Body="&lt;p&gt;Simply, more engines = more power, and power is needed for several things, the first of which is, taking off.  At max takeoff weight, a multi-engine aircraft has to be able to lose one engine (after reaching the go/no-go speed) and safely continue the takeoff, which means that if you could just barely fly on 3 motors, you're going to have to have 4 to meet certification (safety) requirements.  For the amazing weights that the 747 can carry, it needs some pretty powerful motors, and all 4 of them, for taking off fully loaded and meeting this requirement.  (Interestingly, if the aircraft is empty and could safely continue the takeoff on 2, it is typically allowed to take off with one engine already inoperative -- to ferry to a maintenance base, for instance.  But this requires no passengers/freight, and thus a very light airplane.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At cruise altitude, more thrust means a higher cruise altitude is possible, which makes for better fuel efficiency.  So while a 4-engine aircraft can certainly fly on 3 engines, and in many cases (depending on weight and outside air temperature) on 2, it can't fly as high as it could with all 4.  The higher cruise altitude not only makes for more efficient flight, it also keeps you above a lot of the weather out there, and in extreme cases, a 2-engine ceiling might not clear all the terrain on your route.  (Again, this depends on weight &amp;amp; temperature.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern engines have amazing reliability, and it's now considered routine to dispatch the twin engine 777 and 767 and A330 on long overwater routes, but 50 years ago, the reliability wasn't as great, so it was considered essential to have the redundancy so that if one engine failed over the middle of the ocean, there was still a comfortable margin, and you weren't now &quot;one motor away&quot; from going swimming.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-01T17:22:01.690" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16497" PostTypeId="2" ParentId="16471" CreationDate="2015-07-01T18:25:11.640" Score="10" Body="&lt;p&gt;I Googled for &quot;a340 360 cockpit view&quot; that returns, with others, &lt;a href=&quot;https://magazin.lufthansa.com/xx/en/fleet/airbus-a340-600-en/panorama-photo-cockpit-a340-600/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this link&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The link is a 360-degree view of the A340 cockpit. Below is a frame grab for one of the angles:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z1v3E.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z1v3E.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="14897" LastEditDate="2019-04-14T13:04:11.200" LastActivityDate="2019-04-14T13:04:11.200" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="16498" PostTypeId="2" ParentId="16480" CreationDate="2015-07-01T18:47:24.370" Score="1" Body="&lt;p&gt;Wikipedia lists are nice, but think about this question backwards to get the &lt;strong&gt;authoritative source&lt;/strong&gt;. Find and parse the manufacturer data on the exact number of airliners sold. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airbus.com/company/market/orders-deliveries/&quot; rel=&quot;nofollow&quot;&gt;Airbus&lt;/a&gt; (or &lt;a href=&quot;http://www.airbus.com/company/market/orders-deliveries/?eID=maglisting_push&amp;amp;tx_maglisting_pi1%5BdocID%5D=67284&quot; rel=&quot;nofollow&quot;&gt;direct link&lt;/a&gt; to the spreadsheet download on that page)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/commercial/#/orders-deliveries&quot; rel=&quot;nofollow&quot;&gt;Boeing&lt;/a&gt; (lots of nice filtering options!)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You could search for older reports or archives of previous years.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-07-01T18:47:24.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16500" PostTypeId="1" CreationDate="2015-07-01T20:43:58.900" Score="8" ViewCount="888" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/12832/why-does-the-boeing-787-engine-nacelle-exhaust-have-such-an-unusual-shape&quot;&gt;here&lt;/a&gt; I found out a lot about chevrons on the Boeing 787, but not enough to satisfy why it results in performance loss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VmhR0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My thinking was originally, if they are &quot;cutting triangular holes&quot; in the &quot;bell cone&quot;, then some part of the exhaust will expand sooner than others. (I'm more of a rocket guy myself). Or you could think of it as &quot;adding triangular extensions&quot; to the optimal bell-cone, in which case some parts of the exhaust will expand later than usual. Or you could meet in the middle, which is probably the best way, but will still result in suboptimal expansion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I find myself wondering about an even simpler analogy: If sound is wasted energy from an engine (that could have gone into thrust), then reducing sound somehow must mean that otherwise wasted energy has actually gone into thrust production and therefor would &lt;strong&gt;boost&lt;/strong&gt; thrust performance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So which is it really, and why?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-01T21:15:49.627" Title="Why does the chevron-shaped engine suffer losses in thrust performance?" Tags="&lt;jet-engine&gt;&lt;noise&gt;&lt;boeing-787&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16501" PostTypeId="2" ParentId="16500" CreationDate="2015-07-01T21:10:39.107" Score="6" Body="&lt;p&gt;The chevrons need a small pressure difference between the fan flow and the surrounding air. Then they will work like small delta wings and create two strong vortices per triangle, which will help to mix fan flow and outer flow. This mixing is responsible for the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11884/do-nacelles-around-aircraft-engines-help-in-reducing-the-engine-sound/11891#11891&quot;&gt;reduced noise&lt;/a&gt;, because it will distribute the kinetic energy of the fan flow over a bigger mass of air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This mixing by itself uses up some of the energy of the fan flow, and thrust is produced by the conversion of the pressure increase due to the fan into kinetic energy. With the chevrons, a little of this kinetic energy is now spent for mixing and cannot contribute to thrust anymore. Hence the reduced efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're right to assume that less sound should mean more thrust. In fact, the sound energy is not evenly distributed over all frequencies, and by adding some noise at frequencies with low noise contribution, the peaks at the lower frequencies which contain most of the noise can be lowered.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-01T21:10:39.107" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16502" PostTypeId="1" AcceptedAnswerId="16508" CreationDate="2015-07-01T21:47:16.923" Score="0" ViewCount="922" Body="&lt;p&gt;I've been recently introduced to the world of mini aircraft, specifically, quadcopters - building them, flying them, calibrating them (apparently, it's such an important point that it deserves its own place on the list :) .  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm about to finish building my own quadcopter (as soon as I can get a power distribution board - hard to find, it seems), and my hands are itching to try and fly it as soon as possible. I've learned a lot about how planes / helicopters / quads fly while in the process of building one. But maybe I haven't not learned enough about it, and was hoping you can help me with one question I have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;em&gt;think&lt;/em&gt; I've learned enough about the types of propellers used in these vehicles, power requirements, controllers, calibration, and whatnot. While searching about these things on the net, and asking a few friends about their experiences, a thought came into my mind:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't be nice if I could, basically, scale all the components of this small, 330mm vehicle I'm building, to make something bigger?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, bigger as in &lt;em&gt;big enough to carry one, maybe 2 people around&lt;/em&gt; ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I really say &quot;hey, let's build a frame X times larger, with stronger materials, lets get 4 motors X times bigger, let's use 4 X-sized variable pitch propellers&quot; and so on and so on, and actually be able to build a quadcopter able to carry people in it? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Yes, yes, I know I'm basically saying &quot;let's build an actual size helicopter, but with 4 propellers instead of one&quot;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you think this is a feasible approach to build such a thing? Is it even remotely possible? Have you had any experience doing such a thing? Any comments will be highly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="9162" LastEditorUserId="15311" LastEditDate="2017-11-18T12:10:31.927" LastActivityDate="2017-11-18T12:10:31.927" Title="Is quadcopter design scalable?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;rotorcraft&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-07-01T23:07:43.630" ContentLicense="CC BY-SA 3.0" />
  <row Id="16503" PostTypeId="1" AcceptedAnswerId="16509" CreationDate="2015-07-01T22:11:01.597" Score="1" ViewCount="3130" Body="&lt;p&gt;Maybe this isn't the right forum for this question but anyway:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;WHY&lt;/strong&gt; does a jet engine work? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know how it works: compress Air -&gt; inject fuel -&gt; ignite -&gt; expand -&gt; thrust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why does this work? Some energy from the expansion is used to turn the turbine which powers the compressor. &lt;strong&gt;Why is this self sustaining?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;btw: It seems to be tricky to keep a jet engine running. There are &lt;a href=&quot;https://www.youtube.com/watch?v=PS1YAX70edc&quot; rel=&quot;nofollow&quot;&gt;examples&lt;/a&gt; that airliner engines sometime stall (Loss of airflow/compression in the engine)&lt;/p&gt;&#xA;" OwnerUserId="9163" LastActivityDate="2018-01-26T15:51:52.187" Title="WHY does a jet engine work?" Tags="&lt;jet-engine&gt;&lt;aircraft-physics&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16504" PostTypeId="1" CreationDate="2015-07-01T22:27:36.360" Score="5" ViewCount="408" Body="&lt;p&gt;The delta wing on Concorde uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevon&quot; rel=&quot;nofollow&quot;&gt;elevon&lt;/a&gt; as its control surface. Is the elevon considered as all-moving control surface?&lt;/p&gt;&#xA;" OwnerUserId="9165" LastEditorUserId="65" LastEditDate="2015-07-02T13:19:24.277" LastActivityDate="2020-12-06T23:30:52.740" Title="Is an elevon (elevator + aileron) considered as an all-moving control surface?" Tags="&lt;flight-controls&gt;&lt;ailerons&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16505" PostTypeId="2" ParentId="16503" CreationDate="2015-07-01T22:49:40.407" Score="2" Body="&lt;p&gt;Newton's Third Law of motion states &quot;For every force of action, there is an equal and opposite force of reaction.&quot;  So if the exhaust is pushed out of the back end of a jet engine with 40,000 lbs. of force, there is 40,000 lbs. of force pushing the jet, and the aircraft to which it's attached, the other direction.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastActivityDate="2015-07-01T22:49:40.407" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16506" PostTypeId="1" AcceptedAnswerId="16507" CreationDate="2015-07-01T23:03:30.973" Score="4" ViewCount="412" Body="&lt;p&gt;I've heard claims that flying a UAV using a Virtual Reality headset (for example, the &lt;a href=&quot;https://www.oculus.com/en-us/&quot; rel=&quot;nofollow&quot;&gt;oculus rift&lt;/a&gt;) is illegal per FAA regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true? I cannot find any definitive answer either way.&lt;/p&gt;&#xA;" OwnerUserId="9167" LastEditorUserId="9167" LastEditDate="2016-07-08T19:07:04.960" LastActivityDate="2016-07-08T19:07:04.960" Title="Is flying a UAV via a VR controller (e.g. Oculus) legal in the US?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-07-02T15:52:21.553" ContentLicense="CC BY-SA 3.0" />
  <row Id="16507" PostTypeId="2" ParentId="16506" CreationDate="2015-07-01T23:33:43.793" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;https://www.faa.gov/uas/model_aircraft/&quot; rel=&quot;nofollow&quot;&gt;Model Aircraft Operations&lt;/a&gt; one of the requirements for flying a model aircraft is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Keep the aircraft within visual line of sight at all times&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are wearing a VR headset, then your &lt;em&gt;visual line of sight&lt;/em&gt; stops at the headset screen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the above linked page lists the &quot;visual line of sight&quot; as a safety guideline. However, according to &lt;a href=&quot;https://www.faa.gov/uas/media/Sec_331_336_UAS.pdf&quot; rel=&quot;nofollow&quot;&gt;Section 336&lt;/a&gt;, an aircraft is not considered a &quot;model aircraft&quot; unless it is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) flown within visual line of sight of the person operating&#xA;  the aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;None of the above restricts you from flying with a friend where one of you is wearing the VR headset and the other is piloting the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-07-01T23:33:43.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16508" PostTypeId="2" ParentId="16502" CreationDate="2015-07-01T23:35:23.783" Score="3" Body="&lt;p&gt;Ducted fan designs like quadcopters are actually somewhat simpler in some ways to design and build than single-rotor helicopters, because the nature of the design means that the rotors don't need the complex mechanical linkages of a helicopter's main rotor; the four rotors can control pitch and bank simply by varying RPM, and so each one can be a fixed-pitch propeller. The design becomes more stable with a variable-pitch rotor design as the possibility of varying thrust with a constant rotor speed reduces unwanted roll moments from gyroscopic forces, but that throws the simplicity argument out the window (and helicopters have potential roll problems during throttle-up as well, some of which had to be solved before the thing could even take off).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yaw is a little trickier, and one potential limiting factor to scaling up the design. The problem is that with all four rotors in a fixed vertical orientation, which is the simplest mechanically, there's nothing to produce lateral thrust to turn the aircraft around the Z-axis (straight up from the ground through the 'copter in level flight). Options include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;One laterally mounted fan. Simple to design, but you're adding one more fan to a design with a lot of high-speed spinning parts already, and the fan would either have to stop and start in opposite directions very often (easy with a little DC motor and plastic fan on a model, much more difficult when scaled up), or the blade pitch would have to be variable, to allow variable thrust to either side while the rotor turns in one direction) which increases complexity again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Two lateral fans, one facing each direction; by varying their power (they'll probably both be spinning at a low idle while in flight) you provide yaw. Advantage is mechanical simplicity of each fan, disadvantage is having not four, not five but at least six fans, reducing &quot;mean time between failures&quot; of at least one of them increasing required maintenance that much more to ensure it doesn't happen in flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Arranging the main four rotors such that each rotor rotates the same way as the rotor in the diagonally opposite corner, and opposite the other two. By reducing the power of fans rotating in one direction and increasing the power of the other, you can induce yaw as the craft will yaw opposite the direction of the faster rotors due to the torque imbalance, without causing the aircraft to also pitch or roll as the total forces in those planes stays constant. The advantage is reducing the need for additional rotors; the four main rotors can provide motion in all three planes. The disadvantage will be slower yaw rates and increased maximum thrust requirements of each rotor basically allowing any two rotors to maintain required lift (a good requirement to have, not a great one to rely on everyday).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Putting the main rotors in tilt mounts and tilting them in rotationally-symmetric ways to induce yaw. It's an intuitive way to induce yaw, and the same tilt-rotor system would also reduce the amount of pitch required of the full aircraft to produce forward motion; just tilt the rotors and keep the fuselage level. Disadvantages include increased mechanical complexity, and the gyroscopic precession induced by trying to tilt a rotating mass which can cause the craft to tumble off its lift vector.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other potential problems with the quad-rotor design include ensuring reliable power distribution (including maintaining some control if a rotor or an engine gives up completely), the lower inertia of the smaller rotors reducing the effectiveness of autorotation in an emergency, the need by many potential customers to fold the design up more compactly than its flight configuration, and the inherent fragility of the design with ducted fans on pivots in the corners of the aircraft, making it more vulnerable to fatal damage in &quot;combat environments&quot; (translated; everyone not on your side shooting whatever they have at you). Because the U.S. military has been a major customer of rotary-wing aircraft and a primary source of R&amp;amp;D funding, the survivability of the design against things like small-arms fire that a helicopter can typically take a few hits from is a definite point of consideration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last problem plaguing the quadrotor is more fundamental, and it is the lack of an answer to this simple question: what can a &quot;full-size&quot; quadrotor aircraft do that cannot already be done as effectively and cheaper with a traditional helicopter? The primary reason quadrotors make good UAVs is that it's easier for a computerized fly-by-wire system to keep them stable, but that is their only advantage to date compared to a single-rotor helicopter, so until the aircar becomes a serious legal and engineering possibility and people want a rotorcraft that is as easy to fly as a car is to drive (or at least easier than a helicopter where you pretty much cannot let go of the cyclic, ever), the quadrotor will likely remain small-scale.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-03T22:09:48.403" LastActivityDate="2015-08-03T22:09:48.403" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16509" PostTypeId="2" ParentId="16503" CreationDate="2015-07-01T23:42:01.247" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Some energy from the expansion is used to turn the turbine which powers the compressor&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And in some engines it turns the turbine which has a large fan attached to the other end. The engine produces more power than needed to run itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the engine, everything is a very careful balance of pressures. Basically the job done by valves in a piston engine is done by careful engineering in a turbine, which is one of the reasons they cost so much. The inflow to the combustion chamber balances the outflow to the power turbine to the point where it wants to go that way - get it a little bit out of balance and you have noisy stalls like you see in the referenced video.&lt;/p&gt;&#xA;" OwnerUserId="1632" LastActivityDate="2015-07-01T23:42:01.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16510" PostTypeId="1" AcceptedAnswerId="16512" CreationDate="2015-07-01T23:59:06.430" Score="3" ViewCount="235" Body="&lt;p&gt;Laser noob here. I don't know what the maximum range on a high powered laser is, nor a low-powered laser for that matter. Just wondering if this is at all possible. I mention four extremities because it would a combination of the four different laser readings of height. I guess it could be most useful over water, but things could get complicated if flying over rough regions with mountains and valleys, but could be helpful if use in conjunction with a map.&lt;/p&gt;&#xA;" OwnerUserId="9105" LastActivityDate="2015-07-02T01:59:57.117" Title="If a plane had a laser/infrared ruler its four extremities pointing downward, could that work as an altimeter device?" Tags="&lt;altitude&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16511" PostTypeId="2" ParentId="16503" CreationDate="2015-07-02T00:07:01.513" Score="6" Body="&lt;p&gt;There are a few points I will make but first off a jet engine is NOT self sustaining. It takes the input of fuel to keep running. The fuel is the source of energy that keeps it running. Now lets look at the mechanics a bit, to simplify things I will use a &lt;a href=&quot;https://en.wikipedia.org/wiki/Ramjet&quot; rel=&quot;noreferrer&quot;&gt;Ramjet&lt;/a&gt; instead of a turbine driven jet since the compression is taken care of by the simple shape of the engine, no moving parts. Lets assume the jet is moving (ram jets dont work at zero speed).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/S5898.png&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When the engine is thrust forward air enters the front &lt;/li&gt;&#xA;&lt;li&gt;The shape of the nozzle compresses (squeezes) the air &lt;/li&gt;&#xA;&lt;li&gt;Fuel is mixed into the air (same as in a carb)&lt;/li&gt;&#xA;&lt;li&gt;The air/fuel mixture enters the combustion chamber&lt;/li&gt;&#xA;&lt;li&gt;The air/fuel mixture is ignited &lt;/li&gt;&#xA;&lt;li&gt;The ignited mixture expands and is directed out of the back&lt;/li&gt;&#xA;&lt;li&gt;The engine (as a result of newtons 3rd law) moves forward (opposite reaction)&#xA;7b. The air/fuel ignition contained enough energy to not only move the engine but the craft as well. Total Energy = Energy to Drive Engine + Energy to Move Object&lt;/li&gt;&#xA;&lt;li&gt;The forward moving force causes air to enter the front of the engine&lt;/li&gt;&#xA;&lt;li&gt;Back to step 1. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;To make this all work the output energy has to be greater than the energy needed to compress the air. This energy comes from the fuel that is added to the mixture. Jet fuel has &lt;a href=&quot;https://en.wikipedia.org/wiki/Energy_density&quot; rel=&quot;noreferrer&quot;&gt;about 46 MJ/Kg&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a turbine engine we simply introduce a compressor mechanism. Instead of relying on the shape of the engine to compress the air, some of the output energy is sacrificed to spin (and operate) the compressor mechanism. It should be noted that shape does play a roll in turbine jets as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gjMrO.jpg&quot; alt=&quot;enter image description here&quot;&gt;  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-02T00:07:01.513" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16512" PostTypeId="2" ParentId="16510" CreationDate="2015-07-02T01:59:57.117" Score="8" Body="&lt;p&gt;Yes, you could create an altimeter using a laser.  And they exist; See &lt;a href=&quot;http://www.renishaw.com/en/laser-altimetry-for-aircraft-and-uavs--25967&quot;&gt;Laser altimetry for aircraft and UAVs by Renishaw&lt;/a&gt; as one example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Laser altimeters, however, have a significant disadvantage over radar altimeters: They can be obscured by weather, like clouds and rain.&lt;/p&gt;&#xA;" OwnerUserId="3037" LastActivityDate="2015-07-02T01:59:57.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16513" PostTypeId="2" ParentId="16504" CreationDate="2015-07-02T04:10:02.327" Score="7" Body="&lt;p&gt;An All-Moving control surface is a surface where the complete structure acts as a stabilizer. For example, in case of a horizontal tailplane which can be completely moved to work as an Elevator - instead of just the trailing edge of the horizontal tailplane moving to work as a control surface. In such cases, it is called a Stabilator (Stabilizer + Elevator). Elevon is a control surface which is part of the main wing, but the trailing edge of the wing is moved to get Yaw and Roll control. This makes Elevon a normal control surface and &lt;strong&gt;Not&lt;/strong&gt; an all moving surface.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="53529" LastEditDate="2020-12-06T23:30:52.740" LastActivityDate="2020-12-06T23:30:52.740" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="16514" PostTypeId="2" ParentId="16314" CreationDate="2015-07-02T04:17:31.607" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/F%C3%A9d%C3%A9ration_A%C3%A9ronautique_Internationale&quot; rel=&quot;nofollow&quot;&gt;FAI&lt;/a&gt; (Fédération Aéronautique Internationale)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;– The World Air Sports Federation, is the world governing body for air&#xA;  sports, aeronautics and astronautics world records. Its head office is&#xA;  in Lausanne, Switzerland.[3] This includes man-carrying aerospace&#xA;  vehicles from balloons to spacecraft, and unmanned aerial vehicles&#xA;  (such as model aircraft and UAVs). It was founded on 14 October 1905.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAI is the international governing body for Acrobatics through its FAI Aerobatics Commission(&quot;Commission Internationale de Voltige Aerienne&quot; – CIVA).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Gliding through &lt;a href=&quot;https://en.wikipedia.org/wiki/FAI_Gliding_Commission&quot; rel=&quot;nofollow&quot;&gt;FAI Gliding Commission&lt;/a&gt;(&quot;International Gliding Commission – IGC&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Hang Gliding and Paragliding through FAI Hang Gliding &amp;amp; Paragliding Commission (&quot;Commission Internationale de Vol Libre – CIVL)&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-02T04:17:31.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16515" PostTypeId="1" CreationDate="2015-07-02T05:27:21.107" Score="18" ViewCount="2031" Body="&lt;p&gt;This is a fanciful question. 747s are allowed to take off on 3 engines for maintenance ferries (I did a couple), but a 2 engine takeoff is not a practical or legal consideration. However, my gut level feeling is that it could be done in optimal conditions, but I'm interested in what the more technically oriented people here have to say.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft for this thought experiment is a 747-400ERF, a freighter with a basic operating weight of 351,088 lbs and a max takeoff weight of 910,000 lbs. Let's say we want to take off and make a 15 minute swing about the countryside around Moses Lake, WA with its 13,500 runway, elevation 1189 feet, on a STP day with no wind. It's flat land, there are no departure or arrival path obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We want to land with no less than 15,000 lbs of fuel, and the takeoff and flying is going to take around 20,000 lbs. Thus our takeoff weight is going to be around 386,000 lbs, which is roughly 42% of the max takeoff weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have half our engines inoperative, but we are significantly less than half as heavy as the max takeoff weight. To make it easy, let's say that engines 2 and 3 are operating (the inner most engines on each side).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what say you?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1467" LastEditDate="2015-07-02T06:19:30.287" LastActivityDate="2015-07-02T06:43:29.710" Title="Can an empty 747-400 with minimal fuel take off on two engines?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16516" PostTypeId="2" ParentId="16495" CreationDate="2015-07-02T05:36:08.620" Score="25" Body="&lt;p&gt;In addition to what Ralph mentioned, up until the mid 1980s, regulations required that aircraft operating long over-water routes or other such routes with a lack of places to divert in the case of emergency must have at least 3 engines. Specifically, this applied to any route that was more than 60 minutes from a diversionary field in areas subject to FAA regulations and 90 minutes in other places. The planes used on these routes during that era consisted of 4-engine aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot;&gt;De Havilland Comet&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot;&gt;Boeing 707&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-8&quot;&gt;Douglas DC-8&lt;/a&gt;, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot;&gt;Boeing 747&lt;/a&gt; as well as 3-engine aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10&quot;&gt;McDonnell Douglas DC-10&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot;&gt;Lockheed L-1011 TriStar&lt;/a&gt;. These regulations were due to engines historically not having been nearly as reliable as they are today. This was especially true of the piston engines used before the jet age, but also of early jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to specifically answer your question, &lt;strong&gt;in order to serve the long-haul trans-Atlantic and trans-Pacific routes for which the Boeing 747 was intended, it was required to have at least 3 engines.&lt;/strong&gt; Boeing apparently decided it preferred to go with 4 and keep them all wing-mounted. This also didn't require as much thrust output per engine, making the engines easier to design, especially at that time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, by the 1980s, jet engines had become sufficiently reliable and powerful that a new class of regulations called &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot;&gt;ETOPS&lt;/a&gt; (previously &quot;Extended-range Twin-engine Operational Performance Standards,&quot; now &quot;ExTended OPerationS&quot;) was developed to allow twin-engine aircraft to fly overseas routes, provided they met certain standards. The first aircraft certified for such operations was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_767&quot;&gt;Boeing 767&lt;/a&gt;, which was allowed to fly trans-Atlantic operations for TWA. Its initial ETOPS certification allowed the 767 to fly up to 90 minutes away from a diversionary field and this was later increased to 120 minutes after TWA had demonstrated success with the 90-minute certification. However, the original ETOPS regulations still limited aircraft to a maximum of 120 minute ETOPS on entry into service and 180 minute ETOPS was only allowed after at least a year of successful operation with 120 minute ETOPS. As such, aircraft designed during this period for long-haul operations, especially trans-Pacific, such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_MD-11&quot;&gt;MD-11&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A340&quot;&gt;Airbus A340&lt;/a&gt;, still went with 3-engine or 4-engine designs. Unfortunately for Airbus and McDonnell-Douglas, those aircraft were released right around the time the FAA began allowing 180 minute ETOPS at release.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The newly-developed &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot;&gt;Boeing 777&lt;/a&gt; was the first aircraft to qualify for 180 minute ETOPS at entry into service. Largely as a result of the efficiency it gained by having only 2 engines, the 777 trounced the A340 in sales, leading the A340 program to an early death. Shortly thereafter, Boeing acquired McDonnell Douglas and ceased production of the MD-11. With the 777 now allowed to fly, not only trans-Atlantic, but also trans-Pacific routes, the need for tri-engine or quad-engine jets to fly those routes vanished. The 777 was then followed by the A330, 787, and A350 in being able to serve those routes. Each of these programs has been very successful, however, their success has largely resulted in the imminent death of the tri-engine and quad-engine models of the past. The A340 has stopped production entirely. The 747 and A380 have had scant new orders over the last few years, leading to the possibility of both programs being cancelled. According to Wikipedia, as of the end of May, the A380 has had no new net orders so far in 2015 and the 747 has had only 3 (and none in 2014.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-07-02T05:36:08.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16517" PostTypeId="2" ParentId="16503" CreationDate="2015-07-02T05:45:06.053" Score="3" Body="&lt;p&gt;Basically, the energy released by burning fuel is used to compress and accelerate the airflow through the engine. While you correctly note that the turbines pull some of that energy back out of the airflow and use it to keep the engine spinning, this is a relatively small fraction. Since accelerating the air backwards produces an equal magnitude, opposite direction force on the engine itself, a large forward force is applied to the engine, which is then ideally used to accelerate the airplane forwards and/or counter the aerodynamic drag forces on the airplane in order to maintain speed during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as why the flow remains front-to-back through a turbine engine core, this has to do with which side is applying more force to the airflow. The compressor stages are designed to produce more force on the air than the turbine stages are, so the net acceleration on the air is toward the back of the engine. &lt;a href=&quot;https://aviation.stackexchange.com/q/11744/755&quot;&gt;This question&lt;/a&gt; covers the topic of airflow through the engine more thoroughly. &lt;a href=&quot;https://physics.stackexchange.com/q/114280/43007&quot;&gt;This question&lt;/a&gt; on Physics.SE also addresses this topic.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2018-01-26T15:51:52.187" LastActivityDate="2018-01-26T15:51:52.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16518" PostTypeId="2" ParentId="16515" CreationDate="2015-07-02T06:18:21.540" Score="15" Body="&lt;p&gt;Hmm... I guess this will come down to how much of the drag is induced drag vs. how much is form drag. The induced drag will obviously be much less, but the form drag will not be much less than flying at the same airspeed at MTOW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the requirement that it must be capable of continuing a takeoff and climbing out at MTOW on 3 engines, though, I'd be very surprised if it weren't capable of doing so at 42% MTOW on 2 engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the most convincing argument in favor of 'yes' I can think of off hand, &lt;a href=&quot;https://youtu.be/Rac87fY6w-M?t=2m36s&quot; rel=&quot;noreferrer&quot;&gt;there's this&lt;/a&gt;. GE flew a 747 on &lt;strong&gt;one&lt;/strong&gt; engine. Granted, that engine happened to be a &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;noreferrer&quot;&gt;GE90-115b&lt;/a&gt;, the world's most powerful commercial jet engine, which is used on the 777-300ER. However, the GE90-115b is rated at 'only' 115,300 lb. of thrust, while a pair of PW 4062s on a 747-400ERF would produce a total of 126,600 lb. GE's aircraft is a modified 747-100. Since Wikipedia lists its operating empty weight at 358,000 lb. and it was hopefully carrying some fuel in addition to that, its weight was likely not much different from the 386,000 lb. in your scenario. Additionally, in GE's case, some of the lift would have to be used to pull against the yawing moment created by flying with only the #2 engine producing thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In light of this, I'd say that the answer is almost certainly, &lt;strong&gt;yes, it's possible&lt;/strong&gt;. Advisable, of course, is a different matter entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FkpLC.jpg&quot; alt=&quot;GE 747-100 Test Bed with GE90-115b&quot;&gt;&#xA;GE's Test Bed 747-100 with the GE90-115b mounted in place of its #2 engine. Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Ge-747-N747GE-020918-03.jpg#/media/File:Ge-747-N747GE-020918-03.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-07-02T06:18:21.540" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16519" PostTypeId="1" AcceptedAnswerId="16521" CreationDate="2015-07-02T06:42:12.380" Score="2" ViewCount="1722" Body="&lt;p&gt;I have been noticing almost every Multirotor vehicle uses a single thin double-bladed propellor on each axis. And yet clearly, there are some that do not fit the norm. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TR0cC.jpg&quot; alt=&quot;YUS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone explain what the effect of each of these changes would do to a normal quadrocopter? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Adding more Propellors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Adding more Blades on each Propellor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Replacing all Blades with Wider Blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) Making the angle of each blade steeper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;5) Replacing propellors with Contra-rotating propellers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;6) Spinning Propellors faster&lt;/p&gt;&#xA;" OwnerUserId="9172" LastEditorUserId="9172" LastEditDate="2015-07-04T10:57:47.807" LastActivityDate="2015-07-04T10:57:47.807" Title="What is the difference between types of propeller?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-07-02T11:44:24.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="16520" PostTypeId="2" ParentId="16515" CreationDate="2015-07-02T06:43:29.710" Score="5" Body="&lt;p&gt;I'm not sure if its possible, but I'll try to arrive at a conclusion by using the following mathematical model. Correct me if I'm wrong :&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Lets assume all the four engines are operative at 80 p.c. of their full thrust &#xA;when they need to take of with MTOW. &#xA;&#xA;So, for MTOW = 910,000 lbs, &#xA;if the plane is using PW4062, thrust generated per engine is 63,300 lbf&#xA;Net thrust T = 63,300*4*0.8 = 202560 lbf (At 80p.c. of full thrust)&#xA;&#xA;Now, for MTOW, Normal Reaction N of the plane = 29120000 lbf&#xA;If, f is the friction force acting on the plane while takeoff, then&#xA;&#xA;T - f = MTOW*(acceleration)&#xA;acceleration = (T - f)/MTOW   -(1)&#xA;&#xA;for taking off with two engines and lesser weight, if the plane is able to&#xA;achieve the above mentioned acceleration, we can safely assume that it should fly.&#xA;&#xA;so, acceleration in case of using only two engines (at 80 p.c. thrust) and lower weight is:&#xA;&#xA;acceleration = (T' - f')/Weight   -(2)&#xA;Now T = 202560lbf&#xA;    T'= 101280lbf&#xA;    f = (u)*910,000lbf&#xA;    f'= (u)*386,000lbf&#xA;weight= 386,000lbf&#xA;MTOW  = 910,000lbf&#xA;&#xA;from our assumption, lets equate 1 and 2 (and we'll use some constant k to be used later)&#xA;&#xA;so, k(T-f)/MTOW = (T'-f')/weight&#xA;    k(202560-u*910,000)/910,000 = (101280 - u*386,000)/386,000&#xA;    202560*k - u*910,000*k = 238768 - u*910,000&#xA;    k = (238768 - u*910,000)/(202560 - u*910,000)&#xA;&#xA;    Now, for u not belonging to the interval (0.222,0.262), k is +ve&#xA;    and for slip ratio (0,1) , u rarely exceeds 0.5&#xA;&#xA;    hence, for k &amp;gt; 0.8, u lies in (0,0.22), which is quite possible.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Hence, acc. to this model, for a coefficient of friction of about 0.23 or below, its possible for an airplane to achieve the velocity required to produce the lift equivalent to the lift required to takeoff with MTOW. If this is possible, then generating the lift required to take off with lesser weight is also possible, theoretically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;p.s.&#xA;Sorry for some liberal assumptions I made in the model. Please correct me if I was wrong anywhere.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-02T06:43:29.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16521" PostTypeId="2" ParentId="16519" CreationDate="2015-07-02T07:18:54.283" Score="3" Body="&lt;p&gt;There should be two parameters you should know about:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Blade loading: The amount of force per unit of area a blade is creating. Like with a wing, you can formulate a &lt;a href=&quot;https://aviation.stackexchange.com/questions/14538/how-to-calculate-the-lift-coefficient-for-the-a320&quot;&gt;lift coefficient&lt;/a&gt;, a dimensionless number which removes the influence of size, air density and speed. Ideally, this number should be between 0.5 and 0.7, so the propeller makes best use of its blade area.&lt;/li&gt;&#xA;&lt;li&gt;Advance ratio, which is the ratio between the circumference of the propeller disc and the height it would screw itself up into the air in one rotation. Increasing the blade angle would directly increase this advance ratio, for example.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now you should be able to guess the answers to your questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Adding more propellers: Will distribute the load over more propellers and helps if blade loading was too high, but makes matters worse if blade loading was low already.&lt;/li&gt;&#xA;&lt;li&gt;Adding more blades: See 1.&lt;/li&gt;&#xA;&lt;li&gt;Replacing blades with wider blades: See 1.&lt;/li&gt;&#xA;&lt;li&gt;Making the angle of all blades steeper: If you run the prop at a lower speed, your blade loading will go up and thrust will be the same (if you don't mess up the flow over the blades by changing the angle). If you run the prop at a higher speed, blade loading will go up; again until the flow cannot cope with the angle anymore. This is similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall&quot;&gt;stalling a wing&lt;/a&gt;. Changing the blade angle is the preferred means of &lt;a href=&quot;https://aviation.stackexchange.com/questions/1381/how-does-a-constant-speed-propeller-work/1384#1384&quot;&gt;adjusting the prop to different flight speeds&lt;/a&gt; in airplanes.&lt;/li&gt;&#xA;&lt;li&gt;Adding a second, &lt;a href=&quot;https://aviation.stackexchange.com/questions/14820/what-is-the-purpose-of-having-contra-rotating-props-on-an-aircraft&quot;&gt;contra-rotating prop&lt;/a&gt; is like adding another sets of props (see 1), but helps to reduce swirl losses. If blade loading was at a proper value before, halving blade loading will create more losses than reducing &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383#15383&quot;&gt;swirl losses&lt;/a&gt;. You add contra-rotating props only if your blade loading was high already.&lt;/li&gt;&#xA;&lt;li&gt;Spinning propellers faster will create more thrust but also more losses. If your thrust is not sufficient, it is better to increase prop diameter (a parameter you forgot to include).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-02T13:37:11.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16522" PostTypeId="2" ParentId="15632" CreationDate="2015-07-02T07:24:02.280" Score="5" Body="&lt;p&gt;Although typical HEPA filters are what's used (speaking from Boeing experience only), it's important to understand how bleed air is used in a typical aircraft environmental control system (ECS). Bleed air is taken from the compressor section of the engine before the fuel is introduced, so it's still relatively clean ambient air. As such, special filtering is not really required, not any more than say a cabin air filter on a car. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because taking bleed air from an engine robs it of power, commercial airliners will generally use a mix of engine bleed air and recirculated cabin air for the ECS. This reduces the amount of bleed air taken from the engines, and improves their efficiency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the HEPA filters become important is for filtering of the recirculated cabin air. If you were to look under the floor of a commercial airliner that's been in service for a few years, there is a lot of collected dust, dirt, hair, and grime from all the people who've sat for hours on end. Since a significant amount of the air you're breathing onboard is recirculated, the HEPA filters are important for filtering out the typical air impurities you get from having a confined space with lots of people, not necessarily from the engine bleed air.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastActivityDate="2015-07-02T07:24:02.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16523" PostTypeId="1" AcceptedAnswerId="54414" CreationDate="2015-07-02T07:43:27.447" Score="17" ViewCount="2755" Body="&lt;p&gt;In 2015, the FAA stated that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;System-wide, air traffic has declined by 24 percent since peak year 2000. The chart in Figure 1.1 shows that air traffic &#xA;  volume is not expected to return to peak levels in the near term.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FXoxn.png&quot; alt=&quot;Traffic Graph 1997-2024&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is talking about traffic in terms of ATC operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question: why was there such a drastic, sustained drop-off?&lt;/strong&gt; I understand that commercial traffic dropped off after 9-11, but I assumed it had since returned to 'normal'. Apparently this is not the case, but are there any other reasons? Is it something with the metric? It doesn't &lt;em&gt;seem&lt;/em&gt; like there are any less people flying, do airline fleets consists of larger jets than 15 years ago?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Info from the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/controller_staffing/&quot; rel=&quot;noreferrer&quot;&gt;Air Traffic Controller Workforce Plan&lt;/a&gt; )&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2020-08-27T05:16:06.567" Title="Why did air traffic levels decrease dramatically in the US through the 2000s?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;usa&gt;&lt;datasets&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16524" PostTypeId="2" ParentId="16523" CreationDate="2015-07-02T07:58:06.330" Score="3" Body="&lt;p&gt;As you can see the steepest drop is not around 2001, but between 2007 and 2009, the years when the current financial crisis began, it is reasonable to assume that many passengers remained home because of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning the size of the aircraft, except for the launch of A380 in october 2007 with Singapore Airlines, I would say that it hasn't increased significantly over the last 15 years.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-07-02T07:58:06.330" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16525" PostTypeId="1" AcceptedAnswerId="16528" CreationDate="2015-07-02T08:37:40.893" Score="0" ViewCount="462" Body="&lt;p&gt;Can a plane lift off the ground at the point when there is the same amount of lift as weight? Or does lift have to be greater?&lt;/p&gt;&#xA;" OwnerUserId="9173" LastActivityDate="2015-07-02T09:26:07.907" Title="Can an airplane lift off the ground when lift is equal to weight?" Tags="&lt;takeoff&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-07-02T09:53:54.140" ContentLicense="CC BY-SA 3.0" />
  <row Id="16527" PostTypeId="2" ParentId="16381" CreationDate="2015-07-02T08:53:43.303" Score="3" Body="&lt;h2&gt;Calculating Thrust&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;One design required sixteen 20-inch (~50 cm) propellers to lift a person. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These were unducted but I doubt that any 15cm ducted fan produces more thrust than eight 50cm propellers can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.quadrouas.nl/?page_id=64&quot; rel=&quot;nofollow noreferrer&quot;&gt;Autonomous human transport&lt;/a&gt; for details of how the designer calculated thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He used Thrust (pounds) = R&lt;sup&gt;2&lt;/sup&gt;D&lt;sup&gt;4&lt;/sup&gt;T&lt;sub&gt;c&lt;/sub&gt; where T&lt;sub&gt;c&lt;/sub&gt; is an empirically measured constant for which he had a value of 2.7734 x 10&lt;sup&gt;-12&lt;/sup&gt;. R is RPM, D is diameter (inches).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine max RPM might be limited by the need to keep the fan tips subsonic (e.g. &amp;lt; M0.5).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that thrust is shown as depending on the fourth power of diameter, sixteen 50cm propellers will therfore produce about 1000 x the thrust of two 15 cm propellers of the same design at the same RPM.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Ducted vs Free&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It seems you need to be careful when comparing ducted fans with propellers. Using higher RPM to compensate for smaller diameters results in lower efficiencies (you need bigger motors).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Small diameter, high disk loading ducted fans are often conceived to allow the use of a high rpm engine running a direct drive propeller. While these highly loaded fans (if properly designed) will be more efficient than a free propeller of the same diameter, they typically won’t match the efficiency of a larger free propeller (of much lower disk loading)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.esotec.org/hbird/HTML/DuctMyths_F.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Duct Myths, Duct Physics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Twin ducted-fan backpack&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://qz.com/438459/you-could-buy-your-own-personal-jetpack-by-2017/&quot; rel=&quot;nofollow noreferrer&quot;&gt;$150000&lt;/a&gt; &lt;a href=&quot;http://www.martinjetpack.com/technical&quot; rel=&quot;nofollow noreferrer&quot;&gt;Martin Jetpack&lt;/a&gt; uses two ducted fans powered by a 2-litre two-stroke engine of 200hp (~150000 watts?). The fan diameter looks much larger than your 15cm. The width of the machine is given as over 2 meters so I'd estimate the fan diameter is close to 80 cm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The company website doesn't say how they calculated thrust. From their use of larger diameter fans I'd guess there are reasons that 15cm fans are unsuitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Z3pe.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Related&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/9940/1289&quot;&gt;What are the advantages and disadvantages of ducted fans in designs such as the Airbus E-Fan?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-02T15:46:05.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16528" PostTypeId="2" ParentId="16525" CreationDate="2015-07-02T09:21:46.880" Score="3" Body="&lt;p&gt;Yes they can, in fact aircraft regularly lift off the ground when lift is less than weight. They achieve this by rotating the nose, which provides a vertical component of the thrust vector. See the excellent answers to  &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb&quot;&gt;this question&lt;/a&gt; for a detailed explanation. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-02T09:26:07.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16529" PostTypeId="1" CreationDate="2015-07-02T10:20:04.810" Score="2" ViewCount="792" Body="&lt;p&gt;There have been flight accidents which involved structural failure after fast decompression of the cabin, like&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/BOAC_Flight_781&quot; rel=&quot;nofollow&quot;&gt;BOAC Flight 781&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm  thinking about how decompression can destabilize or destroy the structure of a fuselage;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think that a hole pinched into the cabin wall of 1 cm diameter will just cause slow decompression over minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I got the impression that creating a larger hole, like removing a door, can potentially cause severe failure of the fuselage in other places than the hole.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that is the case: what makes a hole large enough to be dangerous?&lt;br&gt;&#xA;And what is the mechanism making a large hole dangerous?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is it that the structural failure comes first, and decompression is just a salient symptom of it?&lt;/p&gt;&#xA;" OwnerUserId="1875" LastActivityDate="2015-07-02T10:34:00.160" Title="What makes fast decompression so dangerous for the fuselage?" Tags="&lt;accidents&gt;&lt;cabin-pressure&gt;&lt;fuselage&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16530" PostTypeId="2" ParentId="16529" CreationDate="2015-07-02T10:34:00.160" Score="9" Body="&lt;p&gt;Often it's the structural failure that results in decompression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The comet (the aircraft in your example) was vulnerable to fatigue cracking that would propagate throughout the fuselage and compromise the structural integrity. Nowadays the fuselage is designed to stop such cracks from reaching further than the next spar and planes are retired when the number of cycles has reached the design limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are factors to take into account when the vessel decompresses. If portions of the vessel are closed off from each other, then the pressure difference between those sections can exceed the tolerance of the divider and cause damage. This caused the floor to collapse when the cargo door blew off in &lt;a href=&quot;https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981&quot;&gt;Turkish Airlines Flight 981&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-07-02T10:34:00.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16531" PostTypeId="1" AcceptedAnswerId="16538" CreationDate="2015-07-02T12:05:46.673" Score="6" ViewCount="12356" Body="&lt;p&gt;I was wondering about roll angle and pitch angle values.&#xA;Will I get same pitch angle at different roll angles and vice-versa?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example. At its initial position, the aircraft is standing on the runway). I got roll and pitch values from a sensor. Lets say X and Y resp. Now, when aircraft is taking off, it is obvious that it will pitch up so  my pitch angle will change to lets say Y1. Now if I look for roll Value, will it be same 'X' or it will be different?&lt;/p&gt;&#xA;" OwnerUserId="9174" LastEditorUserId="9174" LastEditDate="2015-07-02T14:02:42.557" LastActivityDate="2019-07-27T08:23:08.513" Title="What is the relation between roll angle and pitch angle?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;&lt;flight-data-recorder&gt;&lt;attitude&gt;&lt;pitch&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16533" PostTypeId="2" ParentId="14480" CreationDate="2015-07-02T12:36:23.387" Score="1" Body="&lt;p&gt;Let's not forget the liability issue.  Practically every GA accident that results in injury or fatality results with a lawsuit. That's one of the biggest reasons we have such old technology for which we pay such high costs.   &lt;/p&gt;&#xA;" OwnerUserId="9177" LastActivityDate="2015-07-02T12:36:23.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16534" PostTypeId="1" AcceptedAnswerId="16536" CreationDate="2015-07-02T12:51:00.550" Score="7" ViewCount="30609" Body="&lt;p&gt;I was reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/1645/when-how-may-i-replace-the-turn-coordinator-with-an-artificial-horizon&quot;&gt;this question&lt;/a&gt; about Turn Coordinator and Artificial Horizon, and now I want to understand the differences between those two components.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the main difference between Turn Coordinator and Artificial Horizon?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Turn Coordinator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j1xYS.png&quot; alt=&quot;Turn Coordinator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Artificial Horizon:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/66eEH.png&quot; alt=&quot;Artificial Horizon&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2019-01-20T22:28:15.897" Title="What is the difference between Turn Coordinator and Artificial Horizon?" Tags="&lt;flight-instruments&gt;&lt;glass-cockpit&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16535" PostTypeId="2" ParentId="16534" CreationDate="2015-07-02T13:14:51.813" Score="7" Body="&lt;p&gt;&lt;strong&gt;Turn Coordinator&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is actually a &lt;a href=&quot;https://en.wikipedia.org/wiki/Turn_and_slip_indicator&quot; rel=&quot;noreferrer&quot;&gt;turn and slip indicator&lt;/a&gt;. It tells you if you are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;turning or not&lt;/li&gt;&#xA;&lt;li&gt;slipping or not&lt;/li&gt;&#xA;&lt;li&gt;skidding or not&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Artificial Horizon&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Attitude_indicator&quot; rel=&quot;noreferrer&quot;&gt;attitude indicator&lt;/a&gt;, tells you:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;what is the pitch angle of the airplane when ascending or descending&lt;/li&gt;&#xA;&lt;li&gt;what is the bank angle of the airplane when turning&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;pull to cage&lt;/em&gt; know will cage the instrument, that means it will take its current pitch and bank as the new zero-reference position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In glass cockpits or glass cockpit apps, many flight instruments are combined. It looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nZFOu.png&quot; alt=&quot;Google App&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://play.google.com/store/apps/details?id=com.peixsoft.glasscockpit1000&quot; rel=&quot;noreferrer&quot;&gt;GlassCockpit 1000&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal bar below the white triangle on the top arc is the slip/skid indicator.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;To read more about aircraft turning angles/axes, &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_principal_axes&quot; rel=&quot;noreferrer&quot;&gt;please click here&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;To read more about flight instruments, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_instrument&quot; rel=&quot;noreferrer&quot;&gt;please click here&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-07-02T13:14:51.813" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16536" PostTypeId="2" ParentId="16534" CreationDate="2015-07-02T13:42:23.107" Score="9" Body="&lt;h2&gt;Attitude Indicator&lt;/h2&gt;&#xA;&lt;p&gt;It shows your attitude (nose up / down, bank left / right) relative to a horizontal surface. Basically, it tells you the orientation of the plane if someone were to take a photo of the plane from the outside at this very moment.&lt;/p&gt;&#xA;&lt;p&gt;It does not tell you which way you are going (e.g. you can be nose up but descending).&lt;/p&gt;&#xA;&lt;h2&gt;Turn coordinator&lt;/h2&gt;&#xA;&lt;p&gt;This is actually two instruments in one: the white plane and the little ball.&lt;/p&gt;&#xA;&lt;p&gt;The white plane tells you which way you are yawing (rotation about the normal (vertical) axis)). If you are yawing to the right (e.g. N -&amp;gt; NE -&amp;gt; E), the right wing of the little plane is lower. If you are yawing to the left (e.g. N -&amp;gt; NW -&amp;gt; W), the left wing is lower.&lt;/p&gt;&#xA;&lt;p&gt;If you are yawing at the &lt;em&gt;standard rate&lt;/em&gt; (3 degrees per second), the wing of the little plane will align with the white mark.&lt;/p&gt;&#xA;&lt;h2&gt;Combining the two&lt;/h2&gt;&#xA;&lt;p&gt;Suppose that you manage to yaw the plane to the right while keeping it horizontal, like a spinning top:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rec2l.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;You will get:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/21m7L.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-03T12:55:18.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16537" PostTypeId="2" ParentId="16523" CreationDate="2015-07-02T13:56:48.240" Score="8" Body="&lt;p&gt;People travel by air for mainly two reasons, and both require money:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;business&lt;/li&gt;&#xA;&lt;li&gt;pleasure&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Since the source of that chart is FAA, my answer is mostly related to USA, but it can generalized globally.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Economy&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Years leading to 2000, there was an economic boom. Air travel was increasing. By 2000-2001 (before 9/11), &lt;a href=&quot;https://en.wikipedia.org/wiki/Dot-com_bubble&quot; rel=&quot;nofollow noreferrer&quot;&gt;dot-com collapse&lt;/a&gt; resulted in a recession. This forced companies to lay offs and not to pay for air travel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Economy started to get better after that, and then the &lt;a href=&quot;https://en.wikipedia.org/wiki/Financial_crisis_of_2007%E2%80%9308&quot; rel=&quot;nofollow noreferrer&quot;&gt;recession of 2007-2008&lt;/a&gt; hit. Companies learnt an even bigger lesson not to spend money on &lt;em&gt;luxuries&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Economy started to get better again. Air travel started to increase again, but did not peak and is not predicted to peak to the same level as of 1999-2000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why?&lt;/em&gt;&lt;/strong&gt; After a financial calamity, companies and people are &lt;em&gt;very&lt;/em&gt; reluctant to adopt same spending behaviors as before the calamity, since there is an uncertainty of it happening again.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Airline Mergers&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;After 2000, airlines was one of the industries which was hit the hardest. So they wanted to maximize their profits. That means that &lt;em&gt;all&lt;/em&gt; airplane seats must be occupied. This resulted in fewer flights, and also increasing &lt;a href=&quot;https://en.wikipedia.org/wiki/Codeshare_agreement&quot; rel=&quot;nofollow noreferrer&quot;&gt;codeshares&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many airlines &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airline_mergers_and_acquisitions&quot; rel=&quot;nofollow noreferrer&quot;&gt;acquired other airlines&lt;/a&gt;. In the US alone, several major airlines merged together, eliminating redundant and unneeded flights. This reduced air traffic too.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;General Aviation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Also with economic issues, people started to spend less on their hobbies. As a lot of GA traffic occurs on airports with ATC, this reduced ATC operations too.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Larger Airplanes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/a/16524/65&quot;&gt;Federico has mentioned&lt;/a&gt;, only A380 is the larger aircraft so this reason is not likely to contribute for decline in air traffic. On top of that, A380 is mostly used on international routes whereas the majority of air traffic is domestic.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-07-02T15:30:00.023" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16538" PostTypeId="2" ParentId="16531" CreationDate="2015-07-02T14:27:46.510" Score="11" Body="&lt;p&gt;Roll, pitch and yaw are rotations about the principle body axis of the aircraft. Roll angle, pitch angle and yaw angle together describe the attitude of an aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The principle body axes are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;X-axis is the longitudinal axis pointing out the nose of the aircraft. Rotation about the x-axis is called roll. Roll rate is denoted &lt;span class=&quot;math-container&quot;&gt;$p$&lt;/span&gt;, roll angle is denoted &lt;span class=&quot;math-container&quot;&gt;$\phi$&lt;/span&gt; &lt;/li&gt;&#xA;&lt;li&gt;Y-axis is the lateral axis pointing out the right wing. Rotation about the Y-axis is called pitch. Pitch rate is denoted &lt;span class=&quot;math-container&quot;&gt;$q$&lt;/span&gt;, pitch angle is denoted &lt;span class=&quot;math-container&quot;&gt;$\theta$&lt;/span&gt; &lt;/li&gt;&#xA;&lt;li&gt;Z-axis is the vertical axis pointing down. Rotation about the Z-axis is call yaw. Yaw rate is denoted &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt;, yaw angle is denoted &lt;span class=&quot;math-container&quot;&gt;$\psi$&lt;/span&gt; &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Initially when all angles are 0, the aircraft is wings level, nose pointing at the horizon and heading north. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ge9sN.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angles &lt;span class=&quot;math-container&quot;&gt;$\phi, \theta, \psi$&lt;/span&gt; describe the attitude with respect to this initial positions. They are called &lt;a href=&quot;https://en.wikipedia.org/wiki/Euler_angles&quot; rel=&quot;nofollow noreferrer&quot;&gt;Euler angles&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotations are applied in backwards order, first yaw (&lt;span class=&quot;math-container&quot;&gt;$\psi$&lt;/span&gt;), then pitch (&lt;span class=&quot;math-container&quot;&gt;$\theta$&lt;/span&gt;) and finally roll (&lt;span class=&quot;math-container&quot;&gt;$\phi$&lt;/span&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eSvRp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Iv5uL.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z73ne.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This describes almost every possible attitude uniquely, unless the pitch angle is +/- 90 degrees. Then roll and yaw will become ambiguous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now back to your question. Initially on the runway the roll angle of the aircraft is 0 degrees. If the aircraft pitches up (&lt;span class=&quot;math-container&quot;&gt;$q$&lt;/span&gt; becomes positive for a while), the roll angle will not change. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if initially the roll angle was non-zero, the roll angle will be affected by a pitch-up manoeuvre. You can easily visualise this with your hands. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Open your right hand with the palm facing up, you thumb at a right angle to the fingers. The middle finger is the X-axis, the thumb is the Y axis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now roll your hand 45 degrees counter clockwise, keeping the fingers pointed at the horizon. Your thumb will now point 45 degrees into the air. This was a pure roll manoeuvre, the pitch angle is still 0 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now flap your hand 90 degrees up using your wrist, this is a pitch up manoeuvre since you rotate about your thumb axis which is the Y axis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you see that your fingers are all in the same vertical plane, pointing 45 degrees up to your left. If you describe this position with respect to the initial position, the pitch angle is 45 degrees, and the roll angle is 90 degrees. So pitching 90 degrees resulted only in 45 degrees of pitch, but also in 45 degrees of extra roll.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the roll-angle was non-zero before we started to pitch, the pitch rotation affect the roll-angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your sensor is not aligned with the body axes of the aircraft, you will see a lot of cross-effects between the angles during a take-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mathematical relation is well described on &lt;a href=&quot;http://www.chrobotics.com/library/understanding-euler-angles&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt;, which is also the source of the images above. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="34686" LastEditDate="2019-07-27T08:23:08.513" LastActivityDate="2019-07-27T08:23:08.513" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="16540" PostTypeId="1" AcceptedAnswerId="16543" CreationDate="2015-07-02T14:52:47.027" Score="6" ViewCount="801" Body="&lt;p&gt;In a C152, flying VFR, if you point your nose up you wouldn't be able to see the runway, thus it would be difficult to keep yourself aligned to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So once you take off with a C152, do you climb in a fixed climb rate or do you level off at a certain altitude whilst over the runway, and start your climb again once you've reached the threshold of the runway?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="595" LastEditDate="2015-07-03T04:57:57.843" LastActivityDate="2015-07-08T14:14:31.053" Title="How can I take off in a straight line if the runway isn't visible ahead?" Tags="&lt;takeoff&gt;&lt;visual-flight-rules&gt;&lt;cessna-152&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16542" PostTypeId="2" ParentId="16540" CreationDate="2015-07-02T15:04:10.737" Score="11" Body="&lt;p&gt;Thats what the compass is for.   Continue to fly runway heading according to the compass &amp;amp; heading indicator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you may not be able to see the runway, you may have other markers.   Even a good cloud in front of the airplane can serve as a VFR reference point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or look out the side to the left-and-right of the plane.  You should be able to tell if you're going straight or turning by what you see going past the sides of your plane.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-07-02T15:04:10.737" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16543" PostTypeId="2" ParentId="16540" CreationDate="2015-07-02T15:18:12.967" Score="8" Body="&lt;p&gt;Generally speaking you continue your climb after rotation although this will depend on the runway, runway conditions and airport procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://flighttraining.aopa.org/students/maneuvers/skills/shortsofttakeoff.html&quot; rel=&quot;nofollow&quot;&gt;Soft Field Take Off&lt;/a&gt;:&lt;/strong&gt; In some cases if you are leaving from a grass strip (still technically a runway) you will go for your soft field take off maneuver. In this case you will actually pop the plane off the ground into ground effect as soon as you can(you will be flying at this point). Then build up speed in ground effect (at a level attitude so you can see the runway fine) then begin your climb out when you have sufficient speed at a climb attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://flighttraining.aopa.org/students/maneuvers/skills/shortsofttakeoff.html&quot; rel=&quot;nofollow&quot;&gt;Short Field Take Off&lt;/a&gt;:&lt;/strong&gt; If the runway is short (or there is an obstacle to clear) you will execute your short field maneuvers. In this case you will take off with 1 notches of flaps. Gun the engine but hold the breaks and let the prop spin up. Then as soon as you hit rotation speed pull back to your best angle of climb. Then when you have cleared your obstacle you can level it out to a normal climb t (best rate or what ever you planed for). In this case clearing the obstacle may be more important than strictly maintaining the runway heading (depending on where the obstacle is). In this maneuver you will focus on your airspeed (to keep from stalling) as well as your attitude indicator and your heading indicator to keep as on course as possible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Air Port Procedures:&lt;/strong&gt; Some airports have special procedures for departing because of obstacles, air spaces, noise abatements etc. For example I fly out of DYL and they have a procedure on runway 23 that calls for a turn to 250 and climb out to 1200 ft before executing any other turns or maneuvers. Once I have cleared the trees I will usually begin my turn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking you fly the runway heading after you have rotated and you do this using the heading indicator &lt;strong&gt;&lt;em&gt;NOT the compass&lt;/em&gt;&lt;/strong&gt;. Since you are in accelerated climbing flight your compass is inaccurate.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-08T14:14:31.053" LastActivityDate="2015-07-08T14:14:31.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16545" PostTypeId="1" AcceptedAnswerId="16553" CreationDate="2015-07-02T16:04:34.147" Score="59" ViewCount="15129" Body="&lt;p&gt;Aviation &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation#History&quot;&gt;dates&lt;/a&gt; back to the 18th century, and since then tremendous research has been put into making aircraft safer and more efficient. Though these efforts have resulted in better aircraft, why are they still not strong enough to keep the passengers alive in case of a fiery crash? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In recent times, especially, it's a rare incident that a plane crashed and even some of its passengers survived. So, why has this issue not yet been resolved?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-07-29T16:15:39.397" LastActivityDate="2016-10-20T07:01:02.767" Title="Even after years of research, why are planes unable to keep passengers alive in case of a fiery crash?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;aircraft-limitations&gt;" AnswerCount="8" CommentCount="17" FavoriteCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="16546" PostTypeId="2" ParentId="16545" CreationDate="2015-07-02T16:17:51.247" Score="12" Body="&lt;p&gt;The question is really a cost benefit analysis of assumed risk. You could fly planes with passengers that had full &lt;a href=&quot;https://en.wikipedia.org/wiki/Nomex&quot;&gt;nomex&lt;/a&gt; suits on, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Parachute&quot;&gt;parachute&lt;/a&gt;, a back up chute, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Personal_flotation_device&quot;&gt;life jacket&lt;/a&gt;, self deploying &lt;a href=&quot;https://en.wikipedia.org/wiki/Lifeboat_(shipboard)&quot;&gt;life rafts&lt;/a&gt; full of food and other neat survival gear. The plane could have a &lt;a href=&quot;http://www.brsaerospace.com/faq.aspx&quot;&gt;full frame chute&lt;/a&gt;, a steel roll cage and the best impact protection available. But all of this adds weight to the plane and thus reduces how many people you can fit. In turn you make less money per flight since its counter productive for flights to be impractically expensive no matter how safe. In the end of the day you alone can not move as far or as fast as a commercial plane nor do you have the resources to make an almost perfectly safe plane. So you compromise and assume risk for the reward of moving fast and semi efficiently. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary it should be noted that some people do have the resources to fly fast and safe. If you had the money to buy a small (or even big) plane you are free to outfit it (with in legal and practical/physical limits) as you like. This could include what ever protection you may desire from what ever emergencies you can think of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last note: its usually the emergencies you cant think of that are the real issues...  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-02T16:17:51.247" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16547" PostTypeId="2" ParentId="16545" CreationDate="2015-07-02T17:03:08.933" Score="3" Body="&lt;p&gt;As it has been said, there is a lot of &quot;cost&quot; and &quot;weight&quot; in the reasons behind this. For small airplanes you have plane-parachute for example but how to make a suck system working for a 200-tons plane flying at 800km/h full of people ? There are real technical challenges behind this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Choices have been made to reduce the probability of a crash instead of adding some stuff to be crash-proof : electronics and hydraulics systems are redundant, emergency procedures, collision avoidance system, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also have to take into account that civil aviation is not fast evolving : adding some new technology requires long time to be tested, validated, and a good reason to add it. The usual flow of event in this case is : crash -&gt; investiguation -&gt; correct what's wrong -&gt; wait for next crash etc...&lt;/p&gt;&#xA;" OwnerUserId="9128" LastActivityDate="2015-07-02T17:03:08.933" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16548" PostTypeId="2" ParentId="16545" CreationDate="2015-07-02T17:25:17.020" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Though these efforts have resulted in better aircraft, even then why are they not strong enough to keep the passengers alive in case of a fiery crash?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;fiery crash&lt;/em&gt; poses many challenges:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Physical&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The occupants of the airplane are subject to a high acceleration the moment the airplane makes contact with the terrain. The &lt;a href=&quot;https://en.wikipedia.org/wiki/G-force#Human_tolerance_of_g-force&quot;&gt;human body can only sustain a dozen of g-force&lt;/a&gt; before sustaining internal damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering an airplane impacting horizontal terrain with a vertical speed of &lt;code&gt;1000 ft/min&lt;/code&gt; (5 m/s), and an airplane which the cargo space deforms one meter: going from 5 to zero m/s in the distance of 1 meter already results in a acceleration of &lt;code&gt;12.5 g&lt;/code&gt; (5 to zero m/s in 0.4 s) which is barely survivable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fire and fumes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;em&gt;fiery crash&lt;/em&gt; would most likely rupture the fuel tanks, spilling the remaining fuel on-board and causing a fire which would release fumes rapidly incapacitating passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Search and rescue deployment&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As airplanes fly routes which have no connection with the ground road network, the time required by the search-and-rescue team to locate and reach the crash site is way too long for saving passengers requiring immediate medical help.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In recent times, especially, it's a rare incident that a plane crashed and even some of its passengers survived. So, why has this issue not yet been resolved?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Road accidents, were of the above three factors only the physical one can be considered, can already result in severe injuries and death.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With airplanes, traveling at a speed faster by one order of magnitude, it is easy to imagine that the consequences of a collision with the terrain are far more dramatic.&lt;/p&gt;&#xA;" OwnerUserId="9138" LastActivityDate="2015-07-02T17:25:17.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16549" PostTypeId="2" ParentId="16523" CreationDate="2015-07-02T17:27:04.483" Score="18" Body="&lt;p&gt;It isn't just one thing, but a vicious cycle:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Airline travel is expensive. One person flying and one person driving end up about the same price once you figure in gas and hotels, but the airline will want that same price for each passenger, while you can fit up to three more people in the same car at practically no additional charge (the extra weight will slightly increase gas costs and at some point everyone you can put in a minivan won't fit in one hotel room, but the incremental costs still don't compare at all). This makes time practically the only advantage to flight, especially for a family group; if you have the time to drive, many people who need to get somewhere don't even consider flying as a viable financial option.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You choose your car, among other things, for a certain level of comfort; the airline sets up their planes for volume over all else. Even the smallest sub-compacts have more legroom (for the front seat passengers at least) than the average economy airline seat. Upgrade to first class and the ride's better, but then the cost doesn't compare at all.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Customer service ratings are at an all-time low. Flight attendants are moving further and further from the &amp;quot;stewardess&amp;quot; role they had in a bygone age when airlines lived and died by their service quality (because regulation gave them little control over anything else in their business model). Now they exist for little else than to make sure nobody dies, or worse, breaks Federal aviation laws. Get them on the plane, give the speech, make sure everyone's belted in for take-off and landing, then get them back off the plane, all without killing themselves or each other. Anything else the the flight crew does during the flight is gravy at this point.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The major U.S. carriers have practically all adopted Spirit's business model. The average person considering air travel today might think Spirit's the only airline that charges you extra for &lt;em&gt;every single&lt;/em&gt; additional amenity or service, but in fact Southwest, a &amp;quot;discount&amp;quot; carrier, is the only one that still rolls 2 checked bags, snacks and drinks into the ticket; American, United, Delta, USAir, they all charge \$25 for the first checked bag and \$50 for the second, and most of them are also charging for any food or drink served on board.&lt;/p&gt;&#xA;&lt;p&gt;This is due to the hypercompetition on price, which is partially our fault as consumers. In a related but different industry, StubHub recently abandoned its &amp;quot;all-inclusive&amp;quot; pricing model, because it saw its sales drop by half due to StubHub being the highest price in most side-by-side comparisons. It's the same with the airlines; if you need a flight, you go to Google or TripAdvisor or Expedia, enter your route and the date window of your trip, sort by price, and pick one of the top three, maybe the top five. That means that anything the airlines can do to lower the price they show you online at first glance gets them the customers, and airlines wanting to keep the all-inclusive model, like Southwest, have to aggressively remind customers that what they see online is what they will end up paying when it's all said and done (hence the &amp;quot;Bags Fly Free&amp;quot; ad campaign that is now painted on their planes' cargo hatches).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Security is a nightmare. I remember a time, not that long ago really, when you put your carryon or purse on the conveyor belt, your coins in a dish, and walked through a metal detector. Simple. You didn't even need a ticket to get into the secured area, so you could meet whomever was flying in at their gate instead of at the curb. Those days are gone, and it will take a couple big technological leaps to get anywhere near that again (like being able to walk through a full-body scanner with your shoes and all your bags, instead of adopting the &amp;quot;felony stop&amp;quot; position in stocking feet with the contents of your briefcase laid out in grey tubs).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The expense of any kind of travel is redefining the idea of a &amp;quot;vacation&amp;quot;. Leisure time overall has been decreasing since the advent of the Information Age with everyone interconnected and instant gratification being practical in more and more aspects of our lives. Those who still use their two weeks a year (if they even get that) for real leisure are opting more and more often for a &amp;quot;staycation&amp;quot;, either staying home relaxing and visiting local attractions, or driving a relatively short distance to a hotel or resort (DFW has two big destinations, the Gaylord Texan and the Great Wolf Lodge, which cater primarily to people who already live in the Metroplex).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Video calling has created a difference between &amp;quot;face to face&amp;quot; and &amp;quot;in person&amp;quot;. They used to be synonymous, but now the kids can not only talk to Grandpa, but see him, and he them, over a mobile phone or a computer with a webcam, at virtually no cost beyond the telecom plan. This development has more thoroughly revolutionized business travel; you no longer need to fly to the corporate office to get face time with an executive or have a big corporate meeting; you just sit down somewhere with a computer, camera and microphone.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;All of these things have deterred all but the most necessary travel by air; getting on a plane is so expensive, so dehumanizing and so uncomfortable that it's only done if you have to get somewhere and can't take the time to drive there (or you have to cross a major body of water to reach it). That has reduced total passenger count, and since a flight only makes a profit if it's very near full, that reduces the number of flights airlines make. However, that decreases total revenue to offset the overhead of the airline (marketing, scheduling, maintenance, etc), so airlines cut costs by slashing services, making a flight on their planes even more miserable, reducing the general desire to fly, reducing passenger count. The vicious cycle continues.&lt;/p&gt;&#xA;&lt;p&gt;This reduction has been offset somewhat by U.S. airlines &amp;quot;rightsizing&amp;quot; their fleets, opting for more flights with smaller planes. This gives passengers their choice of flight times while keeping planes full and pilots/flight attendants employed. Boeing is focusing primarily on this market in new plane orders with the smaller, more efficient 737, 777 and 787, while the original &amp;quot;jumbo jet&amp;quot;, the 747, is on its way out of most passenger fleets and the A380 is struggling outside a couple relative niche buyers like Emirates and Qantas that specialize in ultra-long-haul flights.&lt;/p&gt;&#xA;&lt;p&gt;Increased air cargo flights have also made up some of the difference; boxes don't care nearly as much about being stacked like sardines in an old aircraft (when was the last DC-10/MD-11 you flew in as a passenger? UPS still has &lt;em&gt;dozens&lt;/em&gt; of them in the cargo fleet) with minimal amenities, so thanks to the success of e-commerce, FedEx and UPS are raking it in and growing their air fleets (though they passed on the A380 in part due to Airbus not prioritizing the cargo variant), while American is scheduled to reduce its fleet by 30 planes this year and is still struggling to report a profit even with prices and services cut to the bone.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-11T16:42:35.190" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16550" PostTypeId="2" ParentId="16381" CreationDate="2015-07-02T17:55:05.007" Score="9" Body="&lt;p&gt;A 15 cm diameter fan could maybe lift 4 kg of mass with a tip speed of 0.6M.&lt;/p&gt;&#xA;&lt;p&gt;By increasing the power and the blade chord length (in other words, increasing the solidity of the rotor), this may be increased to maybe 6 kg or more, but a single fan would probably never lift more than 10 kg mass.&lt;/p&gt;&#xA;&lt;p&gt;The thrust of a rotor is &lt;span class=&quot;math-container&quot;&gt;$C_T \cdot \rho \cdot \text{Area} \cdot \text{tip speed}^2$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; = air density (&lt;span class=&quot;math-container&quot;&gt;$1.225~\mathrm{kg~m^{-3}}$&lt;/span&gt; at sea level).&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\text{Area}$&lt;/span&gt; = area of rotor disc (&lt;span class=&quot;math-container&quot;&gt;$\mathrm{m^2}$&lt;/span&gt;)&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\text{tip speed}$&lt;/span&gt; = the linear speed at the tip of the rotor = radial speed * radius.&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$C_T$&lt;/span&gt; = coefficient of thrust. (is usually in the order of 0.02 to 0.05 for small rotors)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Assuming &lt;span class=&quot;math-container&quot;&gt;$C_T$&lt;/span&gt; of &lt;span class=&quot;math-container&quot;&gt;$0.03$&lt;/span&gt;, the calculation shows &lt;span class=&quot;math-container&quot;&gt;$40~\mathrm{N}$&lt;/span&gt; (&lt;span class=&quot;math-container&quot;&gt;$=4~\mathrm{kg}$&lt;/span&gt;) thrust.&lt;/p&gt;&#xA;&lt;p&gt;Disc area is one of the most important parameters, even a 30 cm disc would generate 4 times the thrust. 60 cm would make almost 65 kg.&lt;/p&gt;&#xA;&lt;p&gt;Apparently, a 50 cm diameter disc can possibly generate 45 kg thrust on its own. So two of them could carry and maybe even lift-off a person equipped with this backpack (the person + the system must be less than 90 kg).&lt;/p&gt;&#xA;" OwnerUserId="8079" LastEditorUserId="35463" LastEditDate="2020-12-07T07:15:33.097" LastActivityDate="2020-12-07T07:15:33.097" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="16551" PostTypeId="2" ParentId="9940" CreationDate="2015-07-02T18:05:45.793" Score="8" Body="&lt;p&gt;R W Hovey indicates Ducted Fans are more efficient below 100-110 mph, with 80 % propulsion efficiency (percent of delivered mechanical power that is converted to thrust), above this, a free propeller is better, 85 % efficiency from 200 to 300 mph, up to 400 mph, when it drops to 60 %, and is catched by turbofans, 64 % efficiency at 450 mph; above 500 mph, turbojet leads, but with a low 61 % efficiency, figures for jets start in 40 % at 300 mph.&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-07-02T18:05:45.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16552" PostTypeId="2" ParentId="16545" CreationDate="2015-07-02T18:25:05.600" Score="57" Body="&lt;p&gt;The principal reason plane crashes are less survivable, which nobody &lt;em&gt;really&lt;/em&gt; seems to fully grasp when talking about airliners, is the sheer amount of &lt;em&gt;energy&lt;/em&gt; inherent in a commercial airplane. When you watch a plane coming in for approach, especially a big one like a 747 or A380, it usually seems very docile, with the plane very slowly and gently approaching the runway. The other classic image is the plane cruising at high altitude, perhaps leaving a contrail behind it as it slowly tracks across the sky. We compare these images from our experience to images of cars zooming past us along a busy road (or a racetrack). We then watch racecar drivers walk away from spectacular wrecks, while plane crashes kill everyone aboard, and we wonder why planes can't be made as safe as racecars (or even ordinary passenger cars).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That image of the docile aircraft traversing the friendly skies, however, is a forced perspective caused by a much bigger object much further away from us, and belies the fact that dozens or even hundreds of tons of weight is moving up to three times faster than an Indy car has even been clocked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basic projectile physics; $E = \frac{1}{2}mv^2$. The car in your driveway, if typical, has a &quot;curb weight&quot; (empty tank but otherwise ready to drive) of about a ton and a half, and cruises at speeds between 30 and 70 mph. Converting mph to fps (multiply by 5280, divide by 3600), the energy, in foot-pounds, of a 3000lb car at a freeway speed of 60mph is about 23 million foot-pounds, plus the additional kinetic energy of driver, passengers and cargo. In a collision, this energy is transferred wherever it will go; the object being collided with, the frame of the car, its occupants, etc. Even at these speeds, a collision can permanently injure or kill someone inside (and a full-speed collision on the highway is more often fatal than not). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical airliner, say the B737-700 which is in common use in the U.S. domestic fleet, has an &quot;operating empty mass&quot; (similar to &quot;curb weight&quot; in cars; everything needed to fly except the fuel and flight crew) of about 40 tons. So right there the potential energy of the airliner is 30-40 times the car. It also takes off and lands at roughly 125-150mph, and cruises at up to Mach 0.78, which at 30,000 ft is about 525mph. So, we're also talking about an order of magnitude difference in velocity, and that increases total energy &lt;em&gt;on the square&lt;/em&gt;. Doing the math, an airliner at cruising speed, not counting the energy inherent in its cargo or passengers, will have a total kinetic energy somewhere on the order of 50 &lt;em&gt;billion&lt;/em&gt; foot-pounds. Even with all other things being equal, such as the distance allowed for deceleration and the distribution of impact forces to the passengers, a passenger in a plane crash would be subjected to more than ten times the forces they would in a car crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, all these things can be mitigated in both cases. These numbers more or less compare what a passenger in a car vs a plane would go through if the vehicle plowed head-on into an immovable obstruction at full speed. That doesn't happen often in either case; highways are built in part to minimize the chance a driver will ever face a barrier head-on, and drivers can usually hit the brakes to slow the car and steer to hit in an oblique direction, and even if that won't prevent an impact it lessens the severity of it by the square of the change in relative speed between the car and what it's hitting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, a CFIT (Controlled Flight Into Terrain) is pretty much the worst case scenario for a plane crash (the only worse one I can think of being a midair collision which is &lt;em&gt;extremely&lt;/em&gt; rare especially for airliners), and there are a lot of systems aboard the aircraft to help a pilot realize he's about to do that. A crash landing, such as a belly landing due to hydraulic failure, is usually more survivable because the pilot is doing everything he can to minimize the force of impact and the plane's total kinetic energy, by both slowing the plane's forward velocity and reducing the glide slope. The plane's remaining kinetic energy can then be spent skidding down the runway or over the field instead of being imparted directly into the aircraft's frame and ultimately its passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, that's still a lot of energy for the plane to get rid of, and even with the inherent weight of an airliner, the ability to fly is favored by designers over keeping the cabin in one piece in a crash. That means that the inherently higher risk to life and limb of flying must be mitigated by keeping the planes well-maintained, and putting well-trained, experienced, healthy flight crews in them. Neither can be said for the average car and driver plucked off the street; only the most severe medical conditions are grounds for revocation of a driver's license, while most cars are driven thousands of miles past scheduled maintenance intervals. Cars, therefore, must be designed and built to keep the occupants alive in a collision, despite the ability or even the intentions of the driver. A plane's safety features are only useful when the pilot is doing his job properly; an oxygen mask or even an escape hatch is useless in a CFIT.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-03T01:35:32.880" LastActivityDate="2015-07-03T01:35:32.880" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="16553" PostTypeId="2" ParentId="16545" CreationDate="2015-07-02T20:07:02.130" Score="159" Body="&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The kinetic energy involved in a plane crash is inhumanely high.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Slightly longer answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;We can built bombs which will go through concrete roofs and ceilings of a bunker, counting the number of floors they crash through while descending so they can explode at the level where the bad guys sit and not where the widows and orphans are kept. We could equally well build a plane with this kind of strength, so the fuselage stays intact even when it crashes into a mountainside. That's not the problem.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Limits of the human body&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The problem will be that rescuers will only find dead bodies inside. The human body was &quot;designed&quot; to endure things like running into a tree, but not being hurled around at Mach 0.85 and then being stopped almost instantly. Thanks to years of research we now have quite a good idea where the limits are. Martin Eiband collected a lot of data on this, if you want to know more, google for &quot;Eiband diagrams&quot;. If you want the full picture, read the &lt;a href=&quot;http://oai.dtic.mil/oai/oai?verb=getRecord&amp;amp;metadataPrefix=html&amp;amp;identifier=ADA218434&quot; rel=&quot;noreferrer&quot;&gt;Army Aircraft Crash Survival Guide&lt;/a&gt;. It comes in five volumes, and volume 1 covers the design criteria. The Eiband diagram below is lifted from this source.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/GU9WM.jpg&quot; alt=&quot;Eiband diagram for lying human&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the time scale: A deceleration with 40 g can only be tolerated for a duration of 0.1 seconds; if the deceleration takes more than 1 second, the limit is only 10 g. Now let's see what deceleration distance is required to stop a human with an average deceleration of 10 g. The energy $E$ of a body of the mass $m$ increases with the square of speed $v$:&#xA;$$E = m\cdot\frac{v^2}{2} = m\cdot a\cdot s$$&#xA;At $a = 98.0665$ m/s², the stopping distance $s$ from an initial speed $v$ is $\frac{v^2}{2\cdot a}$:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Car crash at 30&amp;nbsp;m/s: This needs 4.6&amp;nbsp;m and good restraints, but is generally survivable.&lt;/li&gt;&#xA;&lt;li&gt;Free fall at 60&amp;nbsp;m/s terminal velocity: 18.4&amp;nbsp;m. &lt;a href=&quot;http://www.oddee.com/item_96967.aspx&quot; rel=&quot;noreferrer&quot;&gt;A few humans have indeed survived this&lt;/a&gt; by falling into soft ground like a snow-covered conifer forest. This is also the typical approach speed of airliners, and the 18.4&amp;nbsp;m is the fuselage ahead of you. That is the reason why a crash is &lt;a href=&quot;https://aviation.stackexchange.com/questions/11658/where-is-the-safest-seat-in-the-plane&quot;&gt;more survivable&lt;/a&gt; for the occupants in the rear seat rows.&lt;/li&gt;&#xA;&lt;li&gt;Propeller airplane flies into mountain (120&amp;nbsp;m/s): 73.42&amp;nbsp;m. This kind of &lt;a href=&quot;https://en.wikipedia.org/wiki/Crumple_zone&quot; rel=&quot;noreferrer&quot;&gt;crumple zone&lt;/a&gt; is simply not available, and nobody has survived such an impact.&lt;/li&gt;&#xA;&lt;li&gt;Airliner flies into a mountain (240&amp;nbsp;m/s): 293.7&amp;nbsp;m. To make such a crash survivable, every airliner would need to carry a 300 m boom of stiff material around which would be needed as a crumple zone in an accident. Just think what kind of aft fuselage and tail this would require.&lt;/li&gt;&#xA;&lt;li&gt;And to top it: Astronaut on a space walk collides with a satellite in an opposing orbit (16,000&amp;nbsp;m/s): 1305.23&amp;nbsp;km. Note that I had to switch units to keep the number manageable.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Please consider lower deceleration limits for elderly and untrained persons; the limit in the Eiband diagram was established using healthy young pilots (and hogs, chimps and corpses for the higher limits. A lot of blood was spilled to arrive at these numbers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is not the aircraft structure, it is the fact that humans like to go fast but are not built to stop quickly.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-10-19T16:19:27.693" CommentCount="30" ContentLicense="CC BY-SA 3.0" />
  <row Id="16554" PostTypeId="2" ParentId="13422" CreationDate="2015-07-02T20:39:30.703" Score="13" Body="&lt;p&gt;First, for most long-haul flights, the total flight time is beyond one crew's daily maximum allowance (which is usually 8 hours in any 24-hour period; a flight from Sydney to DFW can exceed 16 hours so two crews and additional compensatory rest periods for all crewmen are required during and after an ultra-long-haul). These flights carry two flight crews; one is flying the plane, the other is sleeping. While not on duty, the crewmen are expected to do &lt;em&gt;anything&lt;/em&gt; but think about flying the plane; read, play games, sleep (definitely sleep) etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Extended Range&quot; variants of airliners used for nonstops in excess of a single crew's capabilities must, by FAA regs, have facilities for crew rest. &lt;a href=&quot;http://www.financetwitter.com/2014/08/secret-revealed-the-secret-chambers-where-pilot-cabin-crew-rest-sleep-photos.html&quot;&gt;Here's an article showing a few examples&lt;/a&gt;. While tucked out of the way by necessity, most are actually quite comfortable, often &lt;em&gt;way&lt;/em&gt; better than first-class. Crews usually transition one pilot at a time to keep at least one person out of the way while people are getting into and out of the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, with the autopilot engaged, regulations require only one pilot to be in control of the plane (called the &quot;pilot flying&quot;); the other one, the &quot;pilot not flying&quot;, can read, use electronic devices, go to the lav, even power nap. This is called &quot;in-seat rest&quot; and is allowed by FAA/ICAO regs for short periods of time; there is a procedure to follow for a pilot to start and stop in-seat rest (basically making sure it's safe to do so and that the other pilot is awake, alert and knows the other pilot's entering a rest period) and there must be a certain overlap time where both pilots are not in in-seat rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, your more modern airliner flight decks can integrate music players into the pilots' headsets, &quot;ducking&quot; or muting the music when there is radio traffic. This is allowed even for the pilot flying; the only requirement is that the pilot be able to hear and understand ATC transmissions, but ATC will not be constantly talking to the flight crew (far from it; they have way too much work to do regarding all the other airplanes operating in their airspace). So, the pilot flying can hook up his iPhone and jam out in the headset while keeping watch on the plane. Such devices can only be used during the same periods of flight the passengers would be able to use theirs, and the same requirements of an &quot;airplane mode&quot; etc apply to the crew's devices.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-02T20:39:30.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16555" PostTypeId="1" CreationDate="2015-07-02T20:45:19.297" Score="2" ViewCount="59" Body="&lt;p&gt;I have seen a number of in flight entertainment systems which utilise two 3.5mm jacks for their earphone jacks, instead of the 1 jack with 2 channels normally used in almost all applications. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example (from Singapore Airlines) is shown below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/o8ZUDm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A normal 3.5mm 2-channel jack is shown below as contrast:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/FqBuJm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this done only in airplanes (to the best of my knowledge)? Is there a reason behind this separation of audio channels?&lt;/p&gt;&#xA;" OwnerUserId="5537" LastActivityDate="2015-07-02T20:45:19.297" Title="Why do in-flight entertainment systems separate the left and right channels in their earphone jacks?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-07-02T20:49:32.007" ContentLicense="CC BY-SA 3.0" />
  <row Id="16556" PostTypeId="2" ParentId="16534" CreationDate="2015-07-02T22:11:24.403" Score="9" Body="&lt;p&gt;The primary difference is labelled right on your image of a TC: &quot;NO PITCH INFORMATION&quot;. The artificial horizon is basically a pitch/bank &lt;em&gt;position&lt;/em&gt; indicator, while the turn coordinator is a yaw/bank &lt;em&gt;rate&lt;/em&gt; indicator. The horizon thus shows you how your aircraft is oriented right this instant, while the TC shows you how fast your orientation and/or heading is changing over time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, a correction from some other answers. A Turn Coordinator is &lt;em&gt;not&lt;/em&gt; the same instrument as a Turn/Slip Indicator. They show similar information and are used interchangeably in normal flight, but they indicate slightly different things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a Turn/Slip Indicator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MTDU9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice the much simpler display. When the bar on the needle lines up with either of the home-plate symbols, you are yawing at a two-minute turn rate. No confusion with bank angle or any other indication of attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gyroscope in this device is basically rotating in a plane parallel to the aircraft's wings, and precession of this gyroscope induced by the aircraft turning is what drives the needle. However, a pure banking maneuver to start a &quot;coordinated&quot; turn doesn't show on the gauge; the aircraft has to start rotating relative to its up/down axis. This can make for a rough ride when attempting to bank to begin a turn, especially if that turn is being initiated by an autopilot; there's no gauge on board the aircraft to measure roll rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To solve that problem, the gyroscope in the instrument was canted 30 degrees in the plane from nose to tail; this makes the gyro sensitive to wing roll rate as well as fuselage yaw rate. This new version, the &quot;turn coordinator&quot; allows autopilots (and human pilots) to execute smoother turns in IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there's a downside. Back in the 1920s, flying into a cloud, especially a large one, was often fatal; there was no artificial horizon yet, so once the pilot could no longer see the real horizon, if the plane's attitude were upset he'd be unable to recover. Then a pilot, Howard Stark, worked out a simple method using only the TSI and altimeter to recover from an upset; use the rudder to center the yaw needle, then ailerons to center the ball (with neutral yaw, the ball indicates the direction of gravity), and finally level out of any climb or dive until the altimeter is steady. This became known as the Stark 1-2-3 method and it saved a lot of lives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new &quot;turn coordinator&quot;, because it responds to bank as well as yaw, will show you &quot;yawing&quot; again once you proceed to &quot;step 2&quot; and try to level the wings. Therefore, you can't use the Stark method with a Turn Coordinator. To indicate this and thus prevent pilots trying to use it as such, the display of the Turn Coordinator was changed to the symbolic aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0mSbn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The display makes some sense as the gauge will respond to roll rate, so it can be thought of as a combination roll/yaw rate indicator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The modern method to keep an airplane in stable flight in IMC instead involves the artificial horizon:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SPM4o.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a gyroscope mounted in gimbals, calibrated and subtly corrected in flight to rotate parallel to the ground (on an axis parallel to gravity while in level flight), it becomes possible to determine your exact angle of pitch and bank using a simplified representation of the real horizon. Blue is sky, brown is ground. Pull up, you see more sky, less ground. Nose down, just the opposite. Bank left, horizon rotates right, and vice versa, all like the real horizon out the window would be doing if you could see it. The instrument, as you can see, has markings indicating definite angles of pitch and bank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to recover from a minor upset in IMC, you simply pitch and bank to return the horizon to level, then while the horizon is stable, the Turn Coordinator will show you if you're yawing and how to correct it. This reduces the need for a pure yaw indicator in most normal situations. Extreme maneuvers, however, can render the AH unusable, so specialized &quot;spin recovery training&quot; is required to teach pilots how to recognize and quickly recover from extreme instabilities such as spins (uncoordinated stalls) and spiral dives.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-01-20T21:44:17.097" LastActivityDate="2019-01-20T21:44:17.097" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="16557" PostTypeId="1" CreationDate="2015-07-02T23:45:04.247" Score="0" ViewCount="458" Body="&lt;p&gt;I am familiar with the basic aerodynamics of wingtip vortex generation and I know that winglets reduce drag by reducing wingtip vortex generation.  I have never seen any illustration of exactly how winglets interact with wingtip vortices to do this.  I have also heard there is a small thrust component to the winglet's lift but am also unable to visualize this as well.  The multiple designs in use are confusing.  Why not just curve the end of the wing down to inhibit the vortex from spilling upwards?&lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2015-07-03T16:24:53.007" Title="How does the airflow around winglets reduce drag?" Tags="&lt;winglets&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ClosedDate="2015-07-03T11:41:58.230" ContentLicense="CC BY-SA 3.0" />
  <row Id="16558" PostTypeId="1" CreationDate="2015-07-03T01:22:27.883" Score="0" ViewCount="56" Body="&lt;p&gt;When the flaps are deployed there are different increments on the control lever. When they are set to, say flaps 10 or 40 what is the number indicating? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-07-03T01:22:27.883" Title="What type of unit are flaps settings in?" Tags="&lt;flaps&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-07-03T02:33:06.150" ContentLicense="CC BY-SA 3.0" />
  <row Id="16559" PostTypeId="1" CreationDate="2015-07-03T02:10:11.287" Score="6" ViewCount="151" Body="&lt;p&gt;Douglas Rotary is sponsoring a fly-in October 3, 2015 in Douglas, AZ at the Douglas Muni. Airport.  How do we apply to get pilots &lt;a href=&quot;http://www.faasafety.gov/WINGS/pub/learn_more.aspx&quot; rel=&quot;nofollow&quot;&gt;WINGS&lt;/a&gt; credit for their training?&lt;/p&gt;&#xA;" OwnerUserId="9183" LastEditorUserId="167" LastEditDate="2015-07-03T02:29:45.583" LastActivityDate="2015-07-04T03:20:17.037" Title="How do you apply to offer WINGS credit for an event you are sponsoring?" Tags="&lt;faa-wings-program&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16560" PostTypeId="1" AcceptedAnswerId="16564" CreationDate="2015-07-03T03:03:35.133" Score="6" ViewCount="2183" Body="&lt;p&gt;Related question:  &lt;a href=&quot;https://aviation.stackexchange.com/q/800/167&quot;&gt;Do fly-by-wire flight controls in airliners provide artificial feel?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/067101403X&quot; rel=&quot;nofollow noreferrer&quot;&gt;Icefire&lt;/a&gt;, by Judith and Garfield Reeves-Stevens, contains the following passage:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the engineers develop a new plane, they like to give the pilots something familiar to work with, so they adjust the computer controls to feel like a plane the pilots already fly and like.  The Tomcat's one of those jets.  Solid, dependable, every test pilot's flown them.  So every new fly-by-wire plane feels a lot like a Tomcat.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now, let's face it, this is a book featuring the main character stealing, &lt;a href=&quot;https://www.youtube.com/watch?v=DWwkx5XoW_0&quot; rel=&quot;nofollow noreferrer&quot;&gt;and making off with&lt;/a&gt;, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_SR-72&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed SR-72&lt;/a&gt;, so I'm not expecting everything to be a model of technical accuracy, but there could be a rock of truth in the middle of this snowball of fiction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are NATO fly-by-wire fighters designed to feel like F-14 Tomcats?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="1696" LastEditDate="2018-04-18T17:23:31.710" LastActivityDate="2018-04-18T17:23:31.710" Title="Are NATO fly-by-wire fighters designed to feel like F-14 Tomcats?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;jet&gt;&lt;fly-by-wire&gt;&lt;f-14&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16563" PostTypeId="2" ParentId="16557" CreationDate="2015-07-03T05:47:59.357" Score="0" Body="&lt;p&gt;This video perfectly explains what happens, except it doesn't use winglets, but different shape of the wings, but the idea is the same:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=CnvIf3vFEYA&quot; rel=&quot;nofollow&quot;&gt;https://www.youtube.com/watch?v=CnvIf3vFEYA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the video describes is when wings don't have winglets, air flowing under the tip of the wing escapes to the side of the wing and upwards, creating a vortex which reduces lift. Addition of winglet reduces the vortex and thus increases lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the video however, new type of wing is shows that doesn't require winglets all together.&lt;/p&gt;&#xA;" OwnerUserId="9146" LastEditorUserId="9146" LastEditDate="2015-07-03T16:24:53.007" LastActivityDate="2015-07-03T16:24:53.007" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16564" PostTypeId="2" ParentId="16560" CreationDate="2015-07-03T10:50:02.137" Score="10" Body="&lt;p&gt;Probably not.&lt;/p&gt;&#xA;&lt;p&gt;One manufacturer of &amp;quot;Active Control&amp;quot; joysticks, as used in F-35 training simulators &lt;a href=&quot;http://www.stirling-dynamics.com/our-products/active-control/what-is-active-control&quot; rel=&quot;noreferrer&quot;&gt;says&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Because the active control stick is controlled by a computer almost any characteristic can be programmed. Typical and useful characteristics include:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Multi modal feel characteristics - the ability to completely change the stick feel when moving from one flight condition to another, for example, in a vertical take-off and landing aircraft from wing borne to jet borne flight.&lt;/li&gt;&#xA;&lt;li&gt;Variable stiffness characteristics - the control forces can be changed forcing the pilot out of dangerous manoeuvres.&lt;/li&gt;&#xA;&lt;li&gt;Variable range of motion - the available motion range can be changed forcing the pilot out of dangerous manoeuvres.&lt;/li&gt;&#xA;&lt;li&gt;Soft stops - localised increases in the force characteristics can be programmed dramatically into the stick characteristic to warn the pilot of the onset of flight restrictions.&lt;/li&gt;&#xA;&lt;li&gt;Power management cues - in helicopters a major maintenance expense is incurred if the pilot applies too much torque to the rotor. The stick force can be made to reflect the rotor torque through the flight envelope reducing pilot workload in monitoring the torque and operating costs.&lt;/li&gt;&#xA;&lt;li&gt;Stick shake functions - to mimic buffet ad issue warnings to the pilot.&lt;/li&gt;&#xA;&lt;li&gt;The stick can also be made to reproduce the mechanical characteristics of a more conventional stick such as breakout forces at the datum.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I'm unfamiliar with F-14 control stick behaviour but I imagine it has none of the first five characteristics though it might have the last two of these.&lt;/p&gt;&#xA;&lt;p&gt;I don't know if the F-35, for example makes use of these characteristics but it seems likely.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-03T10:50:02.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16565" PostTypeId="1" CreationDate="2015-07-03T11:44:39.410" Score="7" ViewCount="2542" Body="&lt;p&gt;I've always wondered how much the elevator actually needs to deflect in order to cause rotation on takeoff for a large airliner. On videos I can rarely see the elevator moving at all. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd really like to know what the degree required is for a 777, but if someone can provide this for another airliner that would be ok. I presume that it depends on takeoff speed, which is of course variable, but let's see what you can come up with. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-07-05T06:34:54.717" Title="What degree of elevator deflection is required to takeoff?" Tags="&lt;takeoff&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16566" PostTypeId="1" AcceptedAnswerId="16568" CreationDate="2015-07-03T14:31:47.953" Score="16" ViewCount="9294" Body="&lt;p&gt;I have &lt;strong&gt;circled the areas (in yellow)&lt;/strong&gt; under the belly of the 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly are those?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mJHRy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mJHRy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://www.airliners.net/photo/DBA/Boeing-737-3Y0/920711&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="15982" LastEditDate="2017-05-31T15:30:02.073" LastActivityDate="2017-05-31T15:30:02.073" Title="What exactly are those openings in the bellies of many jetliners?" Tags="&lt;airliner&gt;&lt;aircraft-systems&gt;&lt;boeing-737&gt;&lt;feature-identification&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16567" PostTypeId="2" ParentId="16559" CreationDate="2015-07-03T14:40:06.767" Score="0" Body="&lt;p&gt;There's nothing that I can find on the FAA website about this. There is a &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.15,Ch15,Sec2&quot; rel=&quot;nofollow&quot;&gt;document&lt;/a&gt; called &lt;em&gt;Administering WINGS and awards programs&lt;/em&gt; but it doesn't have any useful information that I can see about how to host or sponsor a WINGS credit event.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in the absence of a published process for requesting approval, I'd simply &lt;a href=&quot;https://www.faasafety.gov/support/Submit.aspx&quot; rel=&quot;nofollow&quot;&gt;contact&lt;/a&gt; FAASafety directly and ask them.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-03T14:40:06.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16568" PostTypeId="2" ParentId="16566" CreationDate="2015-07-03T14:51:53.920" Score="28" Body="&lt;p&gt;That's an air inlet -- technically a &quot;Ram Air&quot; inlet -- for the air conditioning packs.  There is a &quot;left&quot; and &quot;right&quot; pack, which supply air to the forward and aft part of the aircraft respectively (although either pack can supply enough air to keep the aircraft pressurized to its max altitude).  They use high temperature/high pressure bleed air from the engines or APU, but they also get airflow from the ambient air which is used to cool the bleed air.  The inlet noted in the question is where the ambient air enters, and there are exhaust vents for this air on the bottom of the aircraft.  THIS air isn't used for the pressurization per se (i.e. it doesn't enter the cabin), but just for cooling the air that will enter the cabin (which came from the compressor in the engines/APU, upstream of the combustion chamber).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground, there are louvers that close to keep water and debris out of these ducts, and fans are used to pull in air in that configuration.  In-flight, the louvers open and airflow is generally sufficient to move the air through the system (although the fans still provide some assist).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While there &lt;strong&gt;is&lt;/strong&gt; some amount of drag here, it's fairly minimal, and the ability to keep the cabin pressurized and cool is sufficiently important that the little bit of drag that's caused here is considered acceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close-up photo of the inlet door (Next-Gen 737):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9zxap.jpg&quot; alt=&quot;Inlet Door - Next Gen 737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close-up photo of the inlet door (Classic 737):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CB6sg.jpg&quot; alt=&quot;Inlet Door - Classic 737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Photo of exhaust louvers:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9mKDy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;source page for all of the above (with technical discussion of the air conditioning &amp;amp; pressurization system): &lt;a href=&quot;http://www.b737.org.uk/airconditioning.htm&quot; rel=&quot;noreferrer&quot;&gt;http://www.b737.org.uk/airconditioning.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=5&amp;amp;ved=0CCwQFjAE&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DB737-Air_Conditioning_Systems_Summary.pdf&amp;amp;ei=l6GWVZOAKsHToASy4ZWgCg&amp;amp;usg=AFQjCNGP-5tlr5_kAdPmDGwL6MdCnwiEdA&amp;amp;sig2=u9s7K6rRoAPIi8ciJLQzLQ&amp;amp;bvm=bv.96952980,d.cGU&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Even more technical description of the system -- text &amp;amp; schematics but no photos&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-07-03T15:02:30.843" LastActivityDate="2015-07-03T15:02:30.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16569" PostTypeId="2" ParentId="16545" CreationDate="2015-07-03T15:21:47.133" Score="8" Body="&lt;p&gt;Because there is only so much acceleration and temperature a human body can survive. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other answers provide detailed explanations how immense the energies of a crash can get, and how expensive it can get when you carry much less passengers because of the space needed by all the extra safety features.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there is another issue: &lt;strong&gt;the rarity of emergencies coupled with the probability of a correct decision regarding the case of an emergency&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume that money would not be an issue, and that we could install some very powerful systems which can increase the number of survivors in a crash, something like installing ejection seats for the passengers, full-frame parachutes or retro-rockets to slow down the aircraft or other far-fetched solutions like wrapping the whole aircraft explosively into a big bubble of some exotic material. These active countermeasures need to be very quickly deployable, so they would need to be triggered explosively. Even these solutions would not save everyone: for example, with ejection seats in military aircraft, there is an approximately 30% chance of receiving lasting injuries, and 10% chance of not surviving at all. With untrained passengers who are on average much less fit than fighter pilots, the survival rate would be lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you might say that if these countermeasures could save even just a few people, they are still better than everyone dieing in the crash? Wrong! We have to consider the likelihood of these countermeasures activating accidentally when there is no emergency at all! Not even counting cases where there &lt;em&gt;is&lt;/em&gt; an emergency, but trying to ditch the aircraft onto a field or into a river might save more lives than activating the countermeasures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The odds of being on an airline flight which results in at least one fatality are &lt;a href=&quot;http://www.planecrashinfo.com/cause.htm&quot; rel=&quot;noreferrer&quot;&gt;1 in 3.4 million&lt;/a&gt;, and this counts even cases where the majority of the passengers survived. As the decision of activating the countermeasures has to be made at least once a couple of minutes (or maybe seconds) otherwise it would be too late, and the average airliner flight lasts between 3 to 6 hours, we have additionally &lt;em&gt;at least&lt;/em&gt; 2 more orders of magnitude. This means that if you can make a correct decision about activating the emergency countermeasures with an accuracy of less than &#xA;99.999999997%, &lt;strong&gt;you will have more cases when they activate in a perfectly ordinary flight than in an emergency&lt;/strong&gt;. Such an accuracy can not be expected from any decision making process, as accidents can have a wide variety of causes and are influenced by many factors from weather to mechanical failures to human psychology. As you can not even get near such an accuracy, such a system would likely kill many thousands times more passengers by activating when it shouldn't, than how many people it could save in actual emergencies.&lt;/p&gt;&#xA;" OwnerUserId="1307" LastEditorUserId="1307" LastEditDate="2015-08-17T06:11:01.250" LastActivityDate="2015-08-17T06:11:01.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16572" PostTypeId="2" ParentId="16224" CreationDate="2015-07-03T16:40:08.523" Score="2" Body="&lt;p&gt;In the past, Singapore Airlines used to have service from Newark Liberty to Singapore Changi Airport and back. Flights 21 and 22 respectively. The travel time from one point to the other was 18.5 hours long...the longest ever passenger flight time in all of history. This was discontinued in 2013.&lt;/p&gt;&#xA;" OwnerDisplayName="user9191" LastActivityDate="2015-07-03T16:40:08.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16573" PostTypeId="1" AcceptedAnswerId="16584" CreationDate="2015-07-03T16:57:17.840" Score="14" ViewCount="3982" Body="&lt;p&gt;For example, I often fly from KCHO to KOXB and almost always get cleared through &lt;a href=&quot;http://skyvector.com/?ll=38.2280516867896,-75.99007065142575&amp;amp;chart=23&amp;amp;zoom=4&amp;amp;plan=A.K6.KCHO:A.K6.KOXB&quot;&gt;R-4005 and R-4006&lt;/a&gt;. Occasionally they will be hot and I will have to go around, wasting time and fuel compared to if I had planned that route originally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anyway to call Patuxent Approach (or Washington Center) on the phone ahead of time to ask if the Restricted Area is hot?&lt;/p&gt;&#xA;" OwnerUserId="4511" LastEditorUserId="2143" LastEditDate="2015-07-03T19:18:35.940" LastActivityDate="2015-07-04T02:36:26.717" Title="How to find out if Restricted Area is &quot;hot&quot; before taking off?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16574" PostTypeId="1" AcceptedAnswerId="16576" CreationDate="2015-07-03T17:04:46.187" Score="18" ViewCount="2907" Body="&lt;p&gt;The Solar Impulse just made big news for flying from Japan to Hawaii on a solar-powered plane in five days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But five days seems really long. Let's do the math on that. The &lt;a href=&quot;https://www.google.com/webhp?sourceid=chrome-instant&amp;amp;ion=1&amp;amp;espv=2&amp;amp;ie=UTF-8#q=japan%20to%20hawaii%20distance&quot;&gt;distance from Japan to Hawaii&lt;/a&gt; is about $6,611 km$, so $6,611 km/5 days/24 hours = 55km/h$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it was flying an average of $55km/h$? That seems too slow to maintain lift.&lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="2265" LastEditDate="2015-07-04T14:10:59.693" LastActivityDate="2015-07-04T14:10:59.693" Title="Why did the Solar Impulse flight take so long?" Tags="&lt;airspeed&gt;&lt;lift&gt;&lt;solar-impulse&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16575" PostTypeId="2" ParentId="16574" CreationDate="2015-07-03T17:22:31.133" Score="12" Body="&lt;p&gt;From here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://info.solarimpulse.com/en/our-adventure/building-a-solar-airplane/#.VZbEQvlVhXo&quot;&gt;Solar Impulse Performance&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Solar Impulse can fly at the same speed than a car, between 36 km/h&#xA;  (20 Kts) and 140 km/h (77 Kts).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;At sea level: minimum speed of 45 km/h (20 Kts) and maximum speed of&#xA;  90 km/h (49 Kts). At maximum altitude: from 57 km/h (31,5 Kts) to 140&#xA;  km/h (77 Kts).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wired.com/2013/05/how-to-fly-solar-impulse/&quot;&gt;Wired.Com article, interview with pilots&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“You have to react quickly because if you go down 50 meters, you reach&#xA;  the maximum speed,” he says of the design limit of the airplane. “If&#xA;  you go up 50 meters you reach the stall speed.”&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The calculated maximum speed is 44 knots (51 mph), but the pilots&#xA;  limit themselves to 35 knots (40 mph). The stall speed — the point at&#xA;  which the airflow separates from the wing and it no longer generates&#xA;  sufficient lift — is just 19 knots (22 mph).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-07-03T17:22:31.133" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16576" PostTypeId="2" ParentId="16574" CreationDate="2015-07-03T17:52:07.180" Score="28" Body="&lt;p&gt;No, it could not fly much faster with the available energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is a question of wing area and dynamic pressure. Solar Impulse 2 has 269.5&amp;nbsp;m² &lt;a href=&quot;http://solartakeoff.com/en/documentation&quot; rel=&quot;nofollow noreferrer&quot;&gt;wing area&lt;/a&gt; to carry its 2.3 tons of mass. This is a wing loading of just 8.53&amp;nbsp;kg/m²; much less than even gliders have (they start at around 30&amp;nbsp;kg/m²). This allows it to fly very slowly; if we assume it flies at the lift coefficient $c_L$ for &lt;a href=&quot;https://aviation.stackexchange.com/questions/4967/how-can-you-find-the-best-altitude-for-range-or-speed/4970?s=2%7C0.0630#4970&quot;&gt;optimum range for propeller aircraft&lt;/a&gt;&#xA;$$c_L = \sqrt{\pi \cdot AR \cdot \epsilon \cdot c_{D0}}$$&#xA;and guess the zero-lift drag coefficient $c_{D0}$ to be 0.029 and the aspect ratio $AR$ to be 19.18, the result is 1.377. This is already close to the maximum lift coefficient, which I expect to be 1.6. Now we need the lift equation to calculate the speed which is needed to keep it flying at this lift coefficient:$$v = \sqrt{\frac{2\cdot m\cdot g}{c_L\cdot S\cdot\rho}}$$&#xA;Let's assume it flies in 9000&amp;nbsp;m altitude where &lt;a href=&quot;http://www.wolframalpha.com/input/?i=density%20of%20air%20at%209000m&quot; rel=&quot;nofollow noreferrer&quot;&gt;air density $\rho$ is only 0.4671&amp;nbsp;kg/m³&lt;/a&gt;, the result is 16.13&amp;nbsp;m/s or 58&amp;nbsp;km/h. Now consider that it will fly at the beginning, late at night and at the end of the flight at lower altitudes, and may not be able to fly a straight course (maybe to fly around bad weather), and the 55&amp;nbsp;km/h look entirely plausible, if not outright speedy. At sea level, the optimum range speed is only 9.96&amp;nbsp;m/s or 35.86&amp;nbsp;km/h, just about its take-off airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying faster would need more energy and would not allow Solar Impulse 2 to recharge its batteries for the night hours. &lt;a href=&quot;https://aviation.stackexchange.com/questions/11911/what-kind-of-wing-surface-area-would-curiosity-need-to-be-able-to-fly-in-the-atm/11935#11935&quot;&gt;Solar flight must be slow&lt;/a&gt; to be possible at all.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-04T13:15:50.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16577" PostTypeId="2" ParentId="16566" CreationDate="2015-07-03T20:00:53.707" Score="7" Body="&lt;p&gt;This specific inlet type is called a &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/National_Advisory_Committee_for_Aeronautics&quot;&gt;NACA&lt;/a&gt; inlet&quot;, &lt;a href=&quot;http://www.flyingmag.com/scoop-naca-scoop&quot;&gt;&quot;NACA scoop&quot;&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/NACA_duct&quot;&gt;&quot;NACA duct&quot;&lt;/a&gt;, since it had been invented by &lt;a href=&quot;https://en.wikipedia.org/wiki/Francis_Rogallo&quot;&gt;Francis Melvin Rogallo&lt;/a&gt; at &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1941/naca-report-713.pdf&quot;&gt;NACA in 1941 (PDF)&lt;/a&gt; and refined by scientists at &lt;a href=&quot;http://www.nasa.gov/centers/ames/home/index.html&quot;&gt;NACA (now NASA) Ames&lt;/a&gt;. Its main advantage is its simplicity: It just needs a properly shaped cutout in the skin and a rounded rear edge, whereas the airscoops it replaces need carefully shaped contours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The working principle is quite similar to that of a delta wing, only in this case the actual wing is missing, and is surrounded by sheet metal. But like on the swept leading edge of a delta wing, the swept left and right edges create a vortex which is swallowed by the actual intake at the rear of the cutout. This helps to create a lot of flow for the given area, even though efficiency is below that of a well-shaped airscoop.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-03T20:59:53.400" LastActivityDate="2015-07-03T20:59:53.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16579" PostTypeId="2" ParentId="9311" CreationDate="2015-07-03T23:02:25.460" Score="1" Body="&lt;p&gt;Yes, you can! &#xA;A MiG-19 was for sale not long ago, also a handmade copy of a Polikárpov I-16, two were build in New Zealand, the first custom-ordered by an Spanish old aviation team, a Russian Space Shuttle, probably never flown, was recently published, the spaceship was offered along with its hangar and a second space flying machine, but becoming aware of these auctions is not easy...&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-07-03T23:02:25.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16581" PostTypeId="1" CreationDate="2015-07-03T23:15:36.543" Score="5" ViewCount="1068" Body="&lt;p&gt;Are commercial pilots allowed to fly internationally? Are Commercial Pilots required to take an Airline Transport Pilot (ATP) program/training to fly internationally? And is a commercial pilot the same as an airline pilot?&lt;/p&gt;&#xA;" OwnerUserId="9197" LastEditorUserId="167" LastEditDate="2015-07-04T02:34:28.467" LastActivityDate="2015-07-04T14:10:00.107" Title="Can I fly internationally as a commercial pilot, without an ATP certificate?" Tags="&lt;commercial-aviation&gt;&lt;pilot-certification&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16582" PostTypeId="1" CreationDate="2015-07-03T23:39:51.620" Score="9" ViewCount="658" Body="&lt;p&gt;I recently damaged my log book by putting it in the washer machine. I have picked through all the pieces and saved what little legible logs are left. I have requested a copy of my 8710 from the FAA. With sudden funding I have decided to pursue a career as a professional pilot. I have contacted the owner of the previous aircraft flown and requested copies of the aircraft logs. With all the information, I plan on reconstructing my log book. My question is, with my 8710 proving that I did receive my license, I also had an additional 40-50 hours of flight time that I would like to put in my log book. Should I expect any future hiccups with additional ratings and employment as a pilot? What else could I do to make this process smoother?&lt;/p&gt;&#xA;" OwnerUserId="9198" LastEditorUserId="1696" LastEditDate="2016-07-05T19:27:22.430" LastActivityDate="2016-07-05T19:27:22.430" Title="How will a damaged logbook affect pursuing a career as a professional pilot?" Tags="&lt;commercial-aviation&gt;&lt;logging&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16583" PostTypeId="2" ParentId="16582" CreationDate="2015-07-04T02:24:09.837" Score="10" Body="&lt;p&gt;Well, you've already covered the &lt;a href=&quot;https://aviation.stackexchange.com/questions/767/how-does-a-pilot-replace-their-logbook-if-it-has-been-lost&quot;&gt;&quot;What to do if you've lost your logbook&quot;&lt;/a&gt; bit.  The remaining bit of your question is a little trickier to answer, but not as bad as you might think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The good part about renting is that as you've noted you can get the rental records &amp;amp; that gives you a good start on at least the hours portion of reconstructing your logs. The Day/Night, Instrument/Simulated Instrument, and destinations (Cross-Country) times may be a bit harder to reconstruct, but with a little luck you'll be able to piece that together too.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Will you have trouble with additional ratings?&lt;/strong&gt; No.&lt;br&gt;&#xA;This is the tricky bit though: You &lt;em&gt;will&lt;/em&gt; need logs that prove that you meet the aeronautical experience requirements for any new rating you're pursuing, so if you're working through your instrument/commercial/multi and you just washed the records of that training time, cross-country time, etc. you're going to need to either reconstruct that (from rental records &amp;amp; landing fee receipts), fly the hours over again, or some combination of the two.&lt;br&gt;&#xA;The same goes for any endorsements you have (tailwheel, high-performance, etc.) - you'll need to get re-endorsed to have a record of those (and if you show up to your next practical test in an aircraft that requires an endorsement the examiner may ask to see that endorsement).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Will you have trouble with employment?&lt;/strong&gt; I doubt it.&lt;br&gt;&#xA;Your certificates are your major qualification, and you'll have those (subject to reconstructing the requisite aeronautical experience entries like I mentioned above).&lt;br&gt;&#xA;You'll want to reconstruct as much of your logs as possible because all that experience &lt;em&gt;should&lt;/em&gt; count when you go sit down with an employer, but if you've &quot;only&quot; washed ~50 hours you'll make up most or all of that experience in your future training.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A few related questions you might want to look at:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/93/what-is-the-best-way-to-keep-logbook-entries-backed-up/&quot;&gt;What is the best way to keep logbook entries backed up?&lt;/a&gt;&lt;br&gt;&#xA;(For my part: I scan each page once I've filled it.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11327/are-there-any-best-practices-for-transitioning-from-paper-logbooks-to-electronic&quot;&gt;Are there any best practices for transitioning from paper logbooks to electronic logbooks?&lt;/a&gt;&lt;br&gt;&#xA;(if you decide to go that route)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-04T02:24:09.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16584" PostTypeId="2" ParentId="16573" CreationDate="2015-07-04T02:36:26.717" Score="8" Body="&lt;p&gt;Restricted areas that have &lt;em&gt;scheduled&lt;/em&gt; times will be noted in the (sectional) chart margins. In this example you'll find this at the bottom of the Washington sectional chart:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/NgYDj.png&quot; alt=&quot;Hours for R-4005/R-4006&quot;&gt;&lt;br&gt;&#xA;Ones without regularly scheduled hot times will say something like &lt;code&gt;48 hrs in advance&lt;/code&gt; or &lt;code&gt;other times by NOTAM&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you've noted though restricted areas with posted hours may not always be &quot;hot&quot; during those hours - sometimes you get lucky. The best way to check if you're going to be lucky prior to departure is to ask Flight Service (1-800-WX-BRIEF): The briefers have access to the same data as ATC, and will know definitively if a restricted area is hot (at least as of the time you call them).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you should still call the controlling agency when airborne to verify the status of any special use airspace prior to entering it (briefers can make mistakes, and some restricted areas may be activated on short notice which means they may go hot while you're enroute).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-04T02:36:26.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16585" PostTypeId="2" ParentId="16581" CreationDate="2015-07-04T02:39:35.207" Score="5" Body="&lt;p&gt;A US rated pilot (private, commercial or ATP) can operate an N- registered airplane anywhere on earth (subject to the persons ability or inability to enter certain countries airspace).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the regional airlines it was common that the first officer only possessed a commercial certificate (the full ATP is earned during the pilots first upgrade training to become a captain).  These first officers will have no restriction on international travel based on their certificate and can operate international flights. These days FOs will have restricted ATPs rather than commercial certificates, but this is unrelated to the ability to operate internationally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of airlines you'll find positions where the only a commercial certificate is necessary and these pilots can operate internationally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airplane in question requires a type rating then if the copilot does not have a full type rating, they will need an &quot;SIC type&quot; to operate internationally. This stems from an ICAO requirement that both pilots be type rated. The SIC type can be added to a private or commercial certificate, not just an ATP so this won't be a restriction based on certificate level. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-04T14:10:00.107" LastActivityDate="2015-07-04T14:10:00.107" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16586" PostTypeId="2" ParentId="16559" CreationDate="2015-07-04T03:20:17.037" Score="3" Body="&lt;p&gt;A fly-in by itself doesn't usually qualify for WINGS credit, but if you're also running educational programs or seminars there's a good chance you've got something that will qualify.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally you'd work with a FAA Safety Team representative to help set up the program so it meets the WINGS credit requirements (they have access to premade presentations, slides/videos, and with a little notice they can usually help find presenters/speakers), and the representative will then coordinate with your regional FAA Safety Team manager to get the programs listed in &lt;a href=&quot;http://www.faasafety.gov/SPANS/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SPANS&lt;/a&gt; so people can sign up and receive credit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an account on &lt;a href=&quot;https://www.faasafety.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;faasafety.gov&lt;/a&gt; you can search the FAASTeam directory for representatives near you:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UcEUw.png&quot; alt=&quot;FAASTeam Online Directory&quot;&gt;&lt;br&gt;&#xA;(I did a cursory search and I didn't see anyone in Douglas, but there are a few folks in Tuscon.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can't get in touch with any of the representatives your best bet is to contact your local FSDO (&lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/sdl/contact/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scottsdale in your case&lt;/a&gt;) directly and ask for the &quot;FAA Safety Team Program Manager&quot; - they'll be able to work with you to get the program coordinated and set up in SPANS.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you intend to do regular events with safety programs it would probably be worth getting yourself or someone else in your group set up as a FAASTeam representative. There's some (really simple/basic) training involved, and usually the regional program manager or one of the lead representatives in your area will want to meet with you just so they know what you look like, and once you're set up you'll be able to submit requests to have your programs listed directly.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-04T03:20:17.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16587" PostTypeId="1" CreationDate="2015-07-04T07:55:51.727" Score="12" ViewCount="12539" Body="&lt;p&gt;I am a masters student in Germany and I am very much interested in pilot training. I had a laser eye surgery (LASIK) 3 years ago. I heard that people who got it are not eligible as a pilot. Is this true for a private licence too?&lt;/p&gt;&#xA;" OwnerUserId="9203" LastEditorUserId="790" LastEditDate="2015-07-04T10:14:23.470" LastActivityDate="2015-07-05T07:51:08.493" Title="Does laser eye surgery prevent me from getting an EASA pilot licence?" Tags="&lt;commercial-aviation&gt;&lt;easa-regulations&gt;&lt;ppl&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16588" PostTypeId="2" ParentId="528" CreationDate="2015-07-04T09:56:24.290" Score="2" Body="&lt;p&gt;Most firework displays peak at about 200 feet above the launching site. Any aircraft low enough to tangle with fireworks is too low anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots see fireworks as little flowers on the ground. They are not big or impressive from the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the individual stars, and even the shells, do not weigh much. Unless a firework went into a jet engine, it could not damage an aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9204" LastActivityDate="2015-07-04T09:56:24.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16590" PostTypeId="2" ParentId="16587" CreationDate="2015-07-04T10:05:22.067" Score="4" Body="&lt;p&gt;In the general case, no, it is not universally disqualifying. That said, general advice doesn't substitute for talking to a flight surgeon who can issue you a medical certificate where you are, and determining exactly what will be required you you, given your history, your procedure, and the rules there in Germany.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But since there are pilots now who've had LASIK in the past, it's definitely worth scheduling the appointment &amp;amp; having that conversation. In the past, when LASIK was newer &amp;amp; less proven, the rules were much more restrictive, but they are much less so today.  Good luck!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: &lt;a href=&quot;http://www.usaeyes.org/lasik/lasik-faa.htm&quot; rel=&quot;nofollow&quot;&gt;this link&lt;/a&gt; is specific to the FAA, but it gives a flavor at least for attitudes in the US medical community toward LASIK. Hopefully European standards are similar.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-07-04T10:10:39.597" LastActivityDate="2015-07-04T10:10:39.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16591" PostTypeId="2" ParentId="16565" CreationDate="2015-07-04T12:36:46.660" Score="3" Body="&lt;p&gt;It depends. Mostly on two parameters:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the position of the center of gravity? A more forward position would require a bigger downforce at the tail, so deflection angles would be bigger. On the 777-200, c.g. positions from 14% to 44% of MAC are allowed.&lt;/li&gt;&#xA;&lt;li&gt;What is the trim setting of the stabilizer? Depending on the setting, more or less deflection is needed to set the whole horizontal tail to the right downforce for rotation.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Further parameters are flap settings, take-off mass, rotation speed and desired rate of rotation, but the first two are the most important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I do not have the official Pilot's Operating Handbook for the Boeing 777, the &lt;a href=&quot;http://www.deltava.org/library/B777%20Manual.pdf&quot; rel=&quot;nofollow&quot;&gt;virtual version&lt;/a&gt; has to do. Sadly, it contains very little information. The &lt;a href=&quot;http://www.reddit.com/r/MH370/comments/20q9u9/for_those_interested_the_boeing_777224_flight/&quot; rel=&quot;nofollow&quot;&gt;more seedy corners of the internet&lt;/a&gt; have maybe more substantial content, but here you are on your own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 777 has a computer based weight and balance system, called Accuload, which will compute the proper take-off trim setting, therefore, no discrete values can be given. With the recommended trim setting, the pilot will apply forward pressure on the control column until roatation speed ($v_R$), relaxing control forces to neutral for smooth rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you would take off with the trim setting for cruise, the elevator would need to be deflected by approx. -10° (trailing edge up) in a simulation with typical parameters. Please note that this is not the regular take-off procedure, and the actual deflection angles are much smaller.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-05T06:34:54.717" LastActivityDate="2015-07-05T06:34:54.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16592" PostTypeId="2" ParentId="15733" CreationDate="2015-07-04T14:06:46.410" Score="5" Body="&lt;p&gt;You don't fall, even in the turns because of the the direction of the body acceleration is toward the helicopter floor, including when the pilot turns. So the body is maintained with a force towards the floor, never towards the open door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On my first ride out to the jungle (Vietnam), I looked for a seat. There weren't any. I was instructed to just sit on the side with feet hanging out. The first ride was interesting, but they soon became routine. The pilot could turn sideways and this force would hold you in. Sometimes we flew so low I thought my feet were touching the treetops. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think about this 40 some years later. Would I sit on the side again without being strapped in ? I don't think so. &lt;/p&gt;&#xA;" OwnerUserId="9205" LastEditorUserId="3201" LastEditDate="2015-07-04T18:42:38.260" LastActivityDate="2015-07-04T18:42:38.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16593" PostTypeId="1" CreationDate="2015-07-04T15:24:59.063" Score="2" ViewCount="703" Body="&lt;p&gt;I was told a story a story by a friend that went along the lines of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On multiple occasions, eastern european military aircraft strayed into Austrian airspace during one of the Yugoslav wars.&lt;/li&gt;&#xA;&lt;li&gt;Neutral Austria did not have air-to-air combat capability in their J35Ö Draken, so the Swiss Air Force F-5s helped them out instead.&lt;/li&gt;&#xA;&lt;li&gt;On one occasion, the Swiss air force came in and swiftly destroyed the aircraft in question before returning to base. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that I'm not completely sure of the exact sequence of events. I cannot find any reference for this story. Other aircraft downing during the war, especially NATO ones, are well covered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did this actually happen?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Updates with a few notes:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This must have occurred before 1995 when the Austrian Air Force outfitted their aircraft with Sidewinders AAM. &lt;/li&gt;&#xA;&lt;li&gt;There is one case of a MIG-21 Pilot deflecting to Austria. Even this event is very vaguely documented.&lt;/li&gt;&#xA;&lt;li&gt;Several sources suggest neutral Austria was very shaken up and upset by the foreign fighter jets overflying their country.&lt;/li&gt;&#xA;&lt;li&gt;Information seems to be generally patchy, as this was before the days of the internet and there appears to have been much confusion and disorder.&lt;/li&gt;&#xA;&lt;li&gt;As much as Switzerland is perceived as neutral, Austria was also very much so since it was a small country sandwiched between the east and west during the cold war.&lt;/li&gt;&#xA;&lt;li&gt;Perhaps there is an international law that the Swiss were obligated to help, but kept it quiet out of concern of negative media publicity?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-07T09:48:48.293" LastActivityDate="2015-07-09T00:06:18.867" Title="Did the Swiss Air Force assist Austria in self-defence during the Yugoslav War?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="14" FavoriteCount="0" ClosedDate="2015-07-09T07:24:31.523" ContentLicense="CC BY-SA 3.0" />
  <row Id="16594" PostTypeId="1" AcceptedAnswerId="17411" CreationDate="2015-07-04T17:27:52.410" Score="16" ViewCount="758" Body="&lt;p&gt;If a reasonably modern fighter was placed into a situation where they had to engage in aerial combat while in IMC (say if radar picked up non-squawking aircraft coming from a hostile military airbase toward a no-fly zone that you're patrolling, and said no-fly zone and its immediate vicinity are full of clouds), could it be done?  What techniques would be used?  Or would the fighters seek to meet each other away from the cloud cover, since aerobatic maneuvering in IMC is generally &lt;a href=&quot;https://aviation.stackexchange.com/questions/12179/aerobatics-in-firm-imc-how-would-one-do-it&quot;&gt;not a good idea&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, if it was an unknown (not necessarily known-hostile) aircraft incoming, could it be intercepted in IMC, or would the intercept have to wait until the unknown aircraft emerged into VMC?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-30T15:33:50.513" Title="Intercepts and aerial combat in IMC (or my no-fly zone is full of clouds?!)" Tags="&lt;military&gt;&lt;instrument-flight-rules&gt;&lt;flight-interception&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16595" PostTypeId="1" AcceptedAnswerId="16599" CreationDate="2015-07-04T17:35:48.130" Score="17" ViewCount="2414" Body="&lt;p&gt;What happens if you are flying along through a Restricted Area (lets assume you're in a J-3 so you're VFR/no transponder, but you have a handheld radio to talk to ATC with) and  said restricted area is activated while you're still in it?  Would this be considered an operational failing on ATC's part, or would such a thing be blamed on the using agency (i.e. they ought to ask ATC &quot;is anyone using this?&quot; before they take it &quot;hot&quot;)?  Are there procedures you should follow in this scenario, other than &quot;fly out of the restricted airspace the fastest way possible and hope whatever hazard caused the R-area to go hot doesn't hit you?&quot;&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2021-02-10T05:05:18.770" Title="Restricted Area &quot;popping up&quot; around you -- can it happen, and what do you do about it?" Tags="&lt;air-traffic-control&gt;&lt;special-use-airspace&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16596" PostTypeId="2" ParentId="16594" CreationDate="2015-07-04T17:42:20.660" Score="18" Body="&lt;p&gt;In the first scenario, where it sounds like you're assuming that the intruder aircraft is known to be hostile even without seeing it, a shot with a radar missile would be unaffected by the IMC, and that scenario is a pretty straight-forward kill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hard part of IMC for a modern fighter aircraft isn't killing the target, it's getting the positive ID on it that's necessary before shooting in order to assure the chain of command that you aren't, in fact, about to kill a neutral or friendly aircraft who's wandered into the wrong place at the wrong time with the wrong squawk.  THAT is where VMC becomes necessary, in most cases, to get the required visual ID on the target.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using radar alone, an interceptor could close to some reasonably short distance (say, inside a mile, with some altitude separation as well), and if the unknown aircraft enters VMC even briefly, then the intercept could be completed to the point where one interceptor makes the visual ID.  With the aircraft being known to be hostile, that interceptor could break away, and a wingman, maintaining position further back, could then take the shot with a radar missile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably, the &quot;bad guy&quot; has some mission to complete, and most of those (though not all) tend to need VMC to accomplish -- dropping bombs or taking photos or whatever.  So chances are probably pretty good that the intruder is going to get to VMC eventually.  (Or, if he drops bombs off of radar/GPS, then that act itself might be sufficient confirmation of hostile intent that the interceptors would be cleared to engage, ensuring that the bandit doesn't live to ever repeat that mission.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-04T17:42:20.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16597" PostTypeId="1" CreationDate="2015-07-04T18:45:37.387" Score="5" ViewCount="238" Body="&lt;p&gt;By placing a de laval nozzle at the inlet, can the resulting supersonic airflow allow a scram jet to operate efficiently?&lt;/p&gt;&#xA;" OwnerUserId="9207" LastActivityDate="2015-07-04T20:00:23.530" Title="Is a subsonic scram-jet reasonable?" Tags="&lt;jet&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16598" PostTypeId="2" ParentId="16597" CreationDate="2015-07-04T20:00:23.530" Score="11" Body="&lt;p&gt;First let's clear up some things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A SCRAM jet is a Supersonic Combustion &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717#14717&quot;&gt;RAm Jet&lt;/a&gt;, where the flow speed in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;combustion area is still supersonic&lt;/a&gt;. Efficient combustion &lt;a href=&quot;https://aviation.stackexchange.com/questions/11949/how-is-combustion-flame-maintained-in-the-combustion-chamber-after-igniters-are/11964#11964&quot;&gt;needs low speeds&lt;/a&gt;, hence a supersonic combustion is not a good solution to maximize efficiency. It needs rapidly mixing and burning fuels like hydrogen, lest most of the thermal energy release happens when the gasses have left the engine.&lt;/li&gt;&#xA;&lt;li&gt;The operating principle of all aircraft engines with continuous combustion is that the kinetic energy of the flow is converted into potential energy, namely pressure. This pressure is needed to convince the hot combustion products to leave the engine at the rear end, where the pressure drops as the flow is accelerated again. If the engine flies at subsonic speed, the first area where supersonic flow is possible is in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13522/can-a-convergent-nozzle-be-used-for-a-supersonic-jet-engine/13719#13719&quot;&gt;convergent-divergent nozzle&lt;/a&gt;. Normally, pressure recovery is too small at subsonic speed, and either some &lt;a href=&quot;https://aviation.stackexchange.com/questions/4966/what-is-the-difference-between-a-turbofan-and-a-turboprop-engine&quot;&gt;turbo machinery&lt;/a&gt; or an &lt;a href=&quot;https://aviation.stackexchange.com/questions/13221/what-are-the-pros-and-cons-of-a-pulsejet/13228#13228&quot;&gt;oscillating pressure wave&lt;/a&gt; is needed to increase compression.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Laval_nozzle&quot; rel=&quot;nofollow noreferrer&quot;&gt;de Laval nozzle&lt;/a&gt; (first developed by Ernst Körting in 1878) is a fixed convergent-divergent nozzle and needs high inlet pressure to function. Placing it at the subsonic inlet would require a near vacuum at the outlet to make it work. Using it in combination with a Ram jet would result in separated, subsonic flow with little pressure recovery in the combustion area, and very little thrust could be produced. In principle such an engine would run, but I doubt that it will even produce enough thrust to result in a net thrust gain. Efficiency would most likely be negative.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-04T20:00:23.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16599" PostTypeId="2" ParentId="16595" CreationDate="2015-07-04T20:39:40.793" Score="25" Body="&lt;p&gt;Assuming your question is for the US airspace.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the activation periods cannot be totally anticipated, the description of the area must reference the possibility of activation announced by NOTAM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The NOTAM notice is normally not shorter than 4 hours before the activation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While IFR flights will be prevented by ATC to enter or transit an active restricted area, non-controlled flights are under the sole responsibility of the pilot, as regard to flying within a restricted area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A VFR pilot must take &lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/&quot; rel=&quot;noreferrer&quot;&gt;NOTAMs&lt;/a&gt; for restricted areas into account when preparing the flight (FSS), and should contact ATC when airborne for confirmation of the activation status.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;From the pilot standpoint&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should not enter an inactive restricted area without contacting the controlling agency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM-3-4-3&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Penetration of restricted areas without authorization from the using&#xA;  or controlling agency may be extremely hazardous to the aircraft and&#xA;  its occupants&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You are not allowed to enter an active restricted area without prior permission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Federal Register, &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/CFR-2012-title14-vol2/pdf/CFR-2012-title14-vol2-sec73-13.pdf&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Part 73, §73.13&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an aircraft within a restricted area between the&#xA;  designated altitudes and during the time of designation, unless he has&#xA;  the advance permission of (a) The using agency described in §73.15; or&#xA;  (b) The controlling agency described in §73.17.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA ATC, as the controlling agency, manages restricted area transit or avoidance, based on activation status, but only for IFR flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot of a non-controlled flight (e.g. VFR) has the sole and complete responsibility for getting all information about the restrictions that may apply during its flight over a restricted area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The briefing with &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_service_station&quot; rel=&quot;noreferrer&quot;&gt;FSS&lt;/a&gt; should include such research, contacting ATC prior to entering the restricted area seems the minimum.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;From controlling / using agencies standpoint&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A restricted area is part of the SUA (Special Use Airspace areas), and is jointly managed by &lt;em&gt;Using&lt;/em&gt; and &lt;em&gt;Controlling&lt;/em&gt; agencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400.2K_w_Chg1_dtd_7-24-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;Procedures for handling airspace matters&lt;/a&gt;, 21-2-4, &lt;em&gt;Times of use&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. The times of use indicate the period during which the using agency&#xA;  is authorized to schedule and use a SUA area. These times should&#xA;  reflect when normal operations are expected to occur. In determining&#xA;  the times of use, the proponent should select the minimum period&#xA;  needed to meet the using agency's requirements. The goal is to capture&#xA;  the majority of the day-to-day activities. When the using agency has a&#xA;  requirement for intermittent, less frequent use of the airspace&#xA;  (outside the specific published timeperiod), a provision to activate&#xA;  the airspace by NOTAM may be stated in the SUA legal description.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does that say? If some periods of activation cannot be anticipated, the phrasing &quot;by NOTAM&quot; must be used.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;NOTAM activation. Use &quot;By NOTAM&quot; or &quot;Other Times by NOTAM&quot; to &#xA;  indicate when a NOTAM must be issued in order to activate the area.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Regarding the notice prior to activation by NOTAM:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e). NOTAMs should be issued as far in advance as feasible to ensure&#xA;  widest dissemination of the information to airspace users. Normally,&#xA;  the minimum advance notice should be at least 4 hours prior to the&#xA;  activation time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE-  Under no circumstances may SUA be activated by&#xA;  a NOTAM unless the words &quot;By NOTAM&quot; or &quot;other times by NOTAM&quot; are&#xA;  stated in the area's legal description.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A 4-hour notice is the minimum usually accepted for the publication of the NOTAM prior to activation of the restricted area. I assume the exceptions would be handled on a case by case  basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An area without a NOTAM mention cannot be activated outside of the published periods. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R-2305 Gila Bend, AZ&#xA;[...]&#xA;Time of designation 0700-2300 local time daily, other times by NOTAM.&#xA;Controlling agency FAA, Albuquerque ARTCC.&#xA;Using agency U.S. Air Force, 58th Fighter Wing, Luke AFB, AZ.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16573/how-to-find-out-if-restricted-area-is-hot-before-taking-off&quot;&gt;How to find out if Restricted Area is “hot” before taking off?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1035/what-should-you-do-if-you-are-forced-to-enter-restricted-or-prohibited-airspace&quot;&gt;What should you do if you are forced to enter restricted or prohibited airspace?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/662/can-gliders-access-restricted-airspace&quot;&gt;Can gliders access restricted airspace?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-18T18:31:56.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16600" PostTypeId="2" ParentId="16587" CreationDate="2015-07-04T21:30:09.777" Score="11" Body="&lt;p&gt;LASIK is a type of &lt;a href=&quot;http://www.geteyesmart.org/eyesmart/glasses-contacts-lasik/refractive-surgery.cfm&quot;&gt;refractive eye surgery&lt;/a&gt; and according to &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/AMC%20and%20GM%20on%20the%20medical%20certification%20of%20pilots%20and%20medical%20fitness%20of%20cabin%20crew.pdf&quot;&gt;EASA's medical standards&lt;/a&gt;, you can be considered &quot;fit&quot; to fly after surgery if several conditions are met. The conditions depend on the class of medical; private pilots usually have a class 2 medical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For class 1:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1)   After refractive surgery,  a fit assessment may be considered,&#xA;  provided that:&lt;br&gt;&#xA;  (i)    pre-operative refraction was not greater than&#xA;  +5 dioptres;&lt;br&gt;&#xA;  (ii)  post-operative stability of refraction has been achieved (less than 0.75  dioptres variation diurnally);&lt;br&gt;&#xA;  (iii) examination of the eye shows no post-operative complications;&lt;br&gt;&#xA;  (iv)  glare sensitivity is within normal standards;&lt;br&gt;&#xA;  (v)   mesopic contrast&#xA;  sensitivity is not impaired;&lt;br&gt;&#xA;  (vi)   review is undertaken by an eye&#xA;  specialist.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For class 2 (private pilot) and LAPL:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After refractive surgery a  fit assessment may be considered provided&#xA;  that there is  stability of refraction, there are no postoperative&#xA;  complications and no increase in  glare sensitivity.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The LBA also has an &lt;a href=&quot;http://www.lba.de/DE/Luftfahrtpersonal/Flugmedizin/FAQ/FAQ_Taetigkeit/FAQ_Augen/FAQ_node.html&quot;&gt;FAQ on vision issues&lt;/a&gt; but it doesn't mention LASIK. It does say, however, that you need an optician to examine you if there are any questions about your vision that an aviation examiner can't determine himself (&lt;em&gt;nicht durch den flugmedizinischen Sachverständigen durchgeführt werden können&lt;/em&gt;). I assume that means that if there's any doubt about your eyes, you'll need to have an additional eye exam.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-04T21:30:09.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16601" PostTypeId="1" CreationDate="2015-07-05T00:19:58.733" Score="8" ViewCount="660" Body="&lt;p&gt;What is the correct procedure to follow if someone is intercepting you (or you are the F-16 driver intercepting someone else, for that matter) and you (or they, if you're the interceptor) get a TCAS RA in the middle of it all?  I'm thinking to cases like &lt;a href=&quot;http://avherald.com/h?article=4414b03b&amp;amp;opt=0&quot;&gt;this situation&lt;/a&gt; where an interceptor may interpret the interceptee's TCAS-triggered maneuvers as signs of noncompliance with the intercept...yet the interceptor may not know just what prompted TCAS to issue the interceptee the RA, and the interceptee must comply lest it is an interloping third party on a collision course!&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="19" LastEditDate="2017-03-02T16:17:33.597" LastActivityDate="2017-03-02T16:17:33.597" Title="What is the correct procedure to deal with a TCAS RA during intercept?" Tags="&lt;tcas&gt;&lt;flight-interception&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16607" PostTypeId="2" ParentId="16601" CreationDate="2015-07-05T11:04:05.000" Score="14" Body="&lt;p&gt;The correct procedure for the interceptee would to follow the TCAS Resolution Advisory as they have generally no idea that they are being intercepted. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The interceptor must ensure that no TCAS RA is generated by switching his transponder to the appropriate mode. This has been standard procedure since the introduction of TCAS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS works by interrogating other aircraft's transponders. These interrogations are done in both Mode 3/A and Mode C as well as in Mode S (UF-0). To ensure that no TCAS RA is generated the interceptor's transponder must not reply to Mode C and Mode S interrogations from the interceptee. Since the source of Mode C interrogations is not encoded in the interrogation, the transponder must not reply to any of these interrogations including those from radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically a transponder could be designed to selectively not reply to Mode S interrogations from the interceptee only, however I think it is common to switch off TCAS Mode-S replies, or even switch  off Mode S entirely. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-07-06T22:18:16.090" LastActivityDate="2015-07-06T22:18:16.090" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16609" PostTypeId="2" ParentId="11260" CreationDate="2015-07-05T12:17:36.880" Score="3" Body="&lt;p&gt;Federico was right on in his comment in that this is a weak 'answer' and yes, I know better than that.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not answering the body, this question does answer the one in the title.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.cnn.com/2015/05/14/politics/white-house-drone-arrest/&quot; rel=&quot;nofollow&quot;&gt;Man detained outside White House for trying to fly drone&lt;/a&gt;, as well as related stories of that day, for an example on what not to do with your UAV...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a synopsis, if I remember the details correctly, a US Federal employee was at a friends house in Washington D.C. and they were playing with the friend's new quad-copter (some might call it a drone). There was much drinking and celebration and the man was flying the quad while quite drunk. He flew it towards the White House and it disappeared. It landed itself on the White House lawn. So, yes, a 'drone' can fly beyond radio range.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-07-07T11:13:26.223" LastActivityDate="2015-07-07T11:13:26.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16610" PostTypeId="1" CreationDate="2015-07-05T12:25:51.343" Score="7" ViewCount="1420" Body="&lt;p&gt;My 18yr old son is currently in Barcelona - first time abroad and in a plane. Being an overprotective parent I thought I'd track his flight so I could see when he had landed safely = and save the data for him so he could see his journey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyhow, I noticed weird spike in the flight graph (which I couldn't save). A sudden jump of 200mph in air speed - and equally sudden reduction - at around 15,000ft. No jump in altitude increase though. Also a rapid change in direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight was on Friday 3rd at around 7.18 am bst leaving from Bristol. Data copied below - any thoughts?&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;BST Latitude Longitude Course  Direction  KTS MPH feet   Rate&#xA;Fri 07:22:11 51.3043   -2.6938 254° West  306 352 10,900 2,338&#xA;Fri 07:22:37 51.2927   -2.7573 255° West  322 371 11,900 2,759&#xA;Fri 07:23:38 51.2674   -2.8943 360° North 503 579 14,900 2,804&#xA;Fri 07:24:24 51.2459   -3.0081 253° West  340 391 16,900 2,365 &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="9215" LastEditorUserId="19" LastEditDate="2016-07-04T15:14:11.180" LastActivityDate="2016-07-04T15:14:11.180" Title="Why did the Flightaware groundspeed readout suddenly spike for this flight?" Tags="&lt;datasets&gt;&lt;online-tracking&gt;&lt;groundspeed&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16611" PostTypeId="2" ParentId="16610" CreationDate="2015-07-05T12:50:11.300" Score="15" Body="&lt;p&gt;Looking into &lt;a href=&quot;http://www.flightradar24.com/data/flights/u26025/#6b29535&quot; rel=&quot;noreferrer&quot;&gt;one set of data&lt;/a&gt; from the the popular Flightradar24 service it is not visible.&lt;/p&gt;&#xA;&lt;p&gt;I think I &lt;a href=&quot;http://flightaware.com/live/flight/EZY6025/history/20150703/0605Z/EGGD/LEBL/tracklog&quot; rel=&quot;noreferrer&quot;&gt;found&lt;/a&gt; the data you're looking at. Since the heading also suddenly changed to (exactly) 360, I'm thinking this is just an invalid data point. Notice that the receiving station jumped between these measurements and something could have happened with the processing in between.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;From the same site:&lt;/em&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Aircraft with an ADS-B transponder broadcast their identification and this three dimensional position (latitude, longitude, altitude)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This simply implies that this service tries to interpolate the speed from the time between two positions. So say that the clock at the receiving station or something is off (for instance, just an idea), it will just screw up the reading. It comes with the disclaimer:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;I believe I witnessed a traffic conflict, altitude deviation, or some other anomaly. Should I report it?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Please don't. Rather, read the terms of use and understand that this data is for casual observation only and not for any operational purpose. FlightAware technology was not designed with the intent to observe safety or regulation anomalies, so please do not try to use it for that purpose.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-05T13:03:45.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16612" PostTypeId="1" CreationDate="2015-07-05T18:27:38.367" Score="6" ViewCount="4911" Body="&lt;p&gt;I am an ATCO working in India. I am trying to understand why an aircraft's rate of descent increases, when its speed increases. I am particularly interested in how it relates to jet engine aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the same for aircraft climb rate?&lt;/p&gt;&#xA;" OwnerUserId="9221" LastEditorUserId="12220" LastEditDate="2015-11-17T20:25:20.853" LastActivityDate="2016-05-13T15:01:30.147" Title="What is the relation between aircraft descent rate and speed?" Tags="&lt;descent&gt;&lt;climb&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16613" PostTypeId="2" ParentId="16612" CreationDate="2015-07-05T19:09:01.017" Score="12" Body="&lt;p&gt;If the pilot commands a certain glide path angle, any change in airspeed will also change vertical speed, because both are connected by the glide path angle $\gamma$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mssfw.png&quot; alt=&quot;Speed vectors&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the vertical speed is air speed$\cdot\sin\gamma$. Climbing or descending makes no difference; only the sign of $\gamma$ changes (positive $\gamma$ means the aircraft climbs). Also the type of propulsion will not affect this basic relationship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since descending reduces potential energy, some other energy will increase. If the aircraft speeds up, its kinetic energy increases until the increase in drag balances the energy gain. Reducing engine thrust or deploying spoilers will limit the speed increase, but for a steep descent, even with idling engines and full spoiler deflection the flight speed will increase.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it the same for aircraft climb rate?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No. In a climb the potential energy must be increased, and the primary source of energy are the engines. Only now will the type of propulsion affect the result: &lt;a href=&quot;https://aviation.stackexchange.com/questions/8365/difference-between-best-rate-of-climb-and-maximum-rate-of-climb/8368#8368&quot;&gt;Both the speeds for the steepest and the fastest climb for propeller aircraft are fairly low&lt;/a&gt;, so an increase in vertical speed will normally be accompanied by a reduction in flight speed, freeing up more excess energy for climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21350/maximum-angle-of-climb-jet-vs-prop/21360#21360&quot;&gt;Jets also need to fly slow for their steepest climb, but need to pick up speed for their fastest climb speed&lt;/a&gt;. This is the more pronounced the lower the bypass ratio of the engines is, so fighter jets need speed to climb quickly. Turbofan-powered airliners fall between propeller aircraft and fighter jets and prefer a moderate speed for their best climb performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is all only true in stationary flight. &lt;a href=&quot;https://aviation.stackexchange.com/questions/11657/how-much-thrust-is-needed-by-an-aircraft-to-have-vertical-takeoff/11661#11661&quot;&gt;In a pull-up, any aircraft can gain altitude quickly by trading kinetic for potential energy&lt;/a&gt;. But this is a transitionary effect - the high climb speed will only last while the aircraft has excess speed to spend.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-18T21:29:00.153" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16614" PostTypeId="1" AcceptedAnswerId="16615" CreationDate="2015-07-04T19:02:31.363" Score="16" ViewCount="830" Body="&lt;p&gt;My flight from Abudhabi to SFO was postponed. Official reason given to us was outside temperatures were too high - around 44+ degree Celsius and aircraft can not take off with full fuel loads at such high temperatures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While sitting at terminal I saw other flights taking off. When I asked staff about those flights, answer was they are short haul - around 4-5 hours distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does out side temperature affect these flights? Does it have anything to do with fuel volume changing with higher temperatures and hence wrong fuel consumption calculations?&lt;/p&gt;&#xA;" OwnerUserId="9259" OwnerDisplayName="user871199" LastEditorUserId="167" LastEditDate="2015-07-05T20:32:13.920" LastActivityDate="2017-03-07T03:43:16.897" Title="Why couldn't my aircraft depart fully fueled on a 44C day?" Tags="&lt;aerodynamics&gt;&lt;aircraft-limitations&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16615" PostTypeId="2" ParentId="16614" CreationDate="2015-07-04T20:25:53.723" Score="20" Body="&lt;p&gt;There are two problems:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, at higher temperatures, the air is less dense; therefore there is less oxygen (by mass) in every cubic metre of it; therefore more air must be ingested by the engine (by volume) for the same quantity of fuel to be completely burnt. If the intake flow rate of air is fixed, then less fuel can be burnt and less power developed compared to a colder air temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second problem is that the lower density of air reduces the lift generated by the aircraft's wings at any speed. To make up for this the aircraft can travel faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practise this means that aircraft operating in &quot;hot and high&quot; conditions—altitude also affects air density—will require longer runways to take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it gets too hot then the aircraft might not have enough runway to get airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For safety reasons the runway must be long enough for the aircraft to come to a stop if the commander decides to reject the take off at the last moment. But fast, heavy aircraft take a long time to stop; so this means the runway must be even longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is lightly loaded then it is not such a problem; there is less mass to accelerate and a lower speed must be obtained for take off. Thus a short flight simply takes a bit longer but still gets off the ground. But for AUH-SFO, this is a very long flight and will require a great deal of fuel to be taken onboard (at a guess I would imagine something on the very rough order of 80 tons). The specifics will vary by aircraft, and by how much is on them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Hot_and_high&quot;&gt;https://en.wikipedia.org/wiki/Hot_and_high&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8565" OwnerDisplayName="Calchas" LastActivityDate="2015-07-04T20:25:53.723" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16616" PostTypeId="2" ParentId="16614" CreationDate="2015-07-05T20:54:33.267" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Does it have anything to do with fuel volume changing with higher temperatures and hence wrong fuel consumption calculations?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I doubt wrong fuel consumption calculations are involved, but fuel density is a limiting factor for some aircraft, both insofar as limiting takeoff weight and possibly prohibiting takeoff. For example, for a 747-400BCF, a minimum fuel density of 6.0 lbs/gal is required up to 820,000 lb. From 820,000 lbs to 870,000 lbs the minimum changes linearly from 6.0 to 6.43. From 820,000 to 870,000 there are also takeoff centre of gravity (CG) restrictions. The CG must be forward of 19.1% MAC&lt;sup&gt;1&lt;/sup&gt; at 820,000 changing linearly to 19.5% MAC at 850,000, then linearly to 20.0% MAC at 870,000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you wish to see this graphically displayed, go to section 1-05-001 of the manual at &lt;a href=&quot;http://terryliittschwager.com/WB/manuals/Boeing_747-400BCF_GPR1_WBM.pdf&quot;&gt;http://terryliittschwager.com/WB/manuals/Boeing_747-400BCF_GPR1_WBM.pdf&lt;/a&gt;, pdf page 69 for lbs, 70 for kgs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also some aircraft have a prohibition against operation in ambient temperatures above a certain point. I seem to remember to remember 54 Celsius for 747-100 and -200 aircraft, but don't hold me to that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;MAC = &lt;a href=&quot;https://en.wikipedia.org/wiki/Chord_%28aeronautics%29#Mean_aerodynamic_chord&quot;&gt;Mean Aerodynamic Chord&lt;/a&gt; of the wing. The position of the CG is usually expressed as a percentage of the MAC where 0% is the leading edge and 100% is the trailing edge. &lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="19" LastEditDate="2015-07-05T21:33:01.573" LastActivityDate="2015-07-05T21:33:01.573" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16617" PostTypeId="2" ParentId="16331" CreationDate="2015-07-05T21:34:42.260" Score="15" Body="&lt;p&gt;What happens to live animals in cargo depends on the type of airplane and the class of cargo compartment they're traveling in. For a typical passenger airliner, if you check your animal as baggage, they're going into the &quot;lower lobe cargo compartment&quot; under the cabin floor. This is classified as a Class C compartment, which essentially means that the crew have no access to it in flight, so it must contain fire detection and extinguishing systems. The applicable regulation is &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.857&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 25.857&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quite simply, there are no considerations for live animals in Class C compartments. If you look in Boeing cargo fire checklists (copyrighted so can't post here, but you might get lucky with Google), the steps in the checklist deal with discharging the Halon into the cargo compartment and adjusting the pressurization system to minimize flow into the cargo compartment. This helps maintain the minimum required Halon concentration to provide the first big knockdown blast to stop the fire from spreading, and then maintain a low-level concentration to keep it suppressed for the length of the diversion to a landing. Unfortunately, that means any live animals will suffocate since Halon displaces oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For dedicated freighters such as the 747-400F/747-8F/777F etc., the main deck area is considered a Class E cargo compartment, which doesn't have a fire extinguishing system. If a fire is detected here, the procedure is to depressurize the entire cabin and minimize/cutoff air flow to the main deck area, and climb/descend to a mid-altitude (somewhere in the 24,000-28,000' range depending on the airplane) to minimize oxygen and help suppress the fire. If animals are transported here, rather than the Class C lower lobe compartments, they may survive. They may become hypoxic and lose consciousness, but there's no Halon to suffocate them. Depending on the length of time for the diversion to safe landing site, the lack of oxygen may be a serious issue for some animals just as it can be for humans, but that's a guess as I'm not a vet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is if you're taking your pet with you on a commercial flight, the safest, most comfortable, and least traumatic place for them is with you as a carry-on item.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastEditorUserId="11671" LastEditDate="2018-04-21T15:37:58.917" LastActivityDate="2018-04-21T15:37:58.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16619" PostTypeId="1" CreationDate="2015-07-06T02:41:12.783" Score="15" ViewCount="2060" Body="&lt;p&gt;Why are there fewer air carrier operations on weekends? Looking at PHX data, we have the following annual trend that clearly shows a weekly drop of about 8% on weekends:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/aKm6Y.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and when I average the data a strong weekly pattern is evident:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/sLH8N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this simply telling us that most traffic is business related? Or is it, in part, that major cargo haulers don't work as much on weekends? As the charts show, we're talking about a 1200 vs 1000 daily operations difference.&lt;/p&gt;&#xA;" OwnerUserId="9227" LastEditorUserId="14197" LastEditDate="2018-04-12T22:48:47.477" LastActivityDate="2018-04-12T22:48:47.477" Title="Why fewer operations on weekends?" Tags="&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16620" PostTypeId="2" ParentId="16619" CreationDate="2015-07-06T03:09:55.780" Score="11" Body="&lt;p&gt;Your data TELLS us that the airlines schedule fewer flights on the weekends, from which we can INFER that there is less demand for travel on those days.  (The numbers of cargo flights at PHX are dwarfed by the numbers of passenger flights there. The data at a major cargo hub like MEM or SDF might be different in that regard.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To what extent that is driven by business travelers or leisure travel patterns, is beyond your data, and might even get into some fairly complex data and calculations that USAir and Southwest and others use to build their schedules.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-06T03:09:55.780" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16621" PostTypeId="2" ParentId="16619" CreationDate="2015-07-06T05:42:54.590" Score="4" Body="&lt;p&gt;After further study, I believe the answer is that the weekday vs weekend effect is caused by business travel. The effect is present at major hubs and weakly present at locations that are either strongly recreational, or are not obviously major business destinations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Aspen shows a fairly uniform day of week distribution:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/fT3Il.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0Jvj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;while the annual data shows obvious trends associated with winter and summer recreational activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, at smaller airports, it might be difficult for airlines to modify the number of flights that support business travelers.&lt;/p&gt;&#xA;" OwnerUserId="9227" LastActivityDate="2015-07-06T05:42:54.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16622" PostTypeId="2" ParentId="16619" CreationDate="2015-07-06T06:15:24.123" Score="6" Body="&lt;p&gt;&lt;strong&gt;Businesses work 5 days a week. Non-business travel happens 7 days a week.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other factors kind of even out: Business travel can still happen on the weekend, but ticket prices are normally cheaper mid-week which attracts non-business travelers.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-07-06T06:15:24.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16624" PostTypeId="1" AcceptedAnswerId="16675" CreationDate="2015-07-06T06:48:10.967" Score="14" ViewCount="2480" Body="&lt;p&gt;What are the ways that engine manufacturers &lt;em&gt;currently&lt;/em&gt; minimize the damage caused to engines in a bird strike?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="923" LastEditDate="2015-07-06T07:09:37.983" LastActivityDate="2015-07-07T20:48:55.193" Title="How do engine manufacturers minimize damage from bird strikes?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;engine&gt;&lt;engine-failure&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16626" PostTypeId="1" AcceptedAnswerId="16627" CreationDate="2015-07-06T07:23:02.520" Score="6" ViewCount="3357" Body="&lt;p&gt;Active fuel management is a technology developed by General Motors, which is used to improve engine efficiency in the times when the engine is operating under loads which are considerably less than the rated load, as shown in this &lt;a href=&quot;https://en.wikipedia.org/wiki/Active_Fuel_Management&quot; rel=&quot;noreferrer&quot;&gt;link&lt;/a&gt;. This technology exploits the property of piston engines where some of the cylinders are turned &lt;strong&gt;OFF&lt;/strong&gt; while only few of them work, and hence improving the overall efficiency of the engine. Can a similar technique be employed on an aircraft's engines, where some of the turbine stages (Compressor or Turbine) are &lt;strong&gt;switched off&lt;/strong&gt; in order to improve the performance efficiency of the engine?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8887" LastEditDate="2015-07-06T13:28:01.330" LastActivityDate="2019-08-07T00:55:09.383" Title="Could turbine or compressor stages of a jet engine be switched off to improve fuel efficiency?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16627" PostTypeId="2" ParentId="16626" CreationDate="2015-07-06T07:31:08.050" Score="13" Body="&lt;p&gt;You &lt;strong&gt;cannot&lt;/strong&gt; &quot;switch off&quot; a stage of a turbine engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As seen &lt;a href=&quot;https://aviation.stackexchange.com/a/8082/1467&quot;&gt;elsewhere&lt;/a&gt; jet engines are a single block mechanically locked together: all the stages (compressor AND turbine) connected to the same shaft. If the shaft turns, all connected stages turn with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can have designs with multiple shafts, but this increases the complexity (design and maintenance) heavily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if we assume for a moment that you could have 1 shaft per stage, stopping one of these would be generally a bad idea.&#xA;For acoustic reasons the number of blades on the stationary part of the stage and those on the rotary part must be prime to each other (example: 37 blades on the stationary side and 39 on the rotary one); this means that when the rotary part stops you cannot align all the blades with the stationary ones, creating drag and losses within the engine, thus &lt;strong&gt;reducing&lt;/strong&gt; the efficiency.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How would efficiency of a Jet Engine change, if we assume for a second that its a possibility, to stop a few stages(turn them into free instead of locked)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You would still decrease the efficiency: compressor stages are the ones actually &lt;a href=&quot;https://aviation.stackexchange.com/a/3308/1467&quot;&gt;pulling the aircraft forward&lt;/a&gt; (you would then produce less thrust*) and the turbine stages are the ones extracting energy from the exahust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*: you could even risk having the flame going upstream if you stop too many compressor stages and not having enough pressure at the combustion chamber inlet.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-07T05:21:16.020" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16628" PostTypeId="1" AcceptedAnswerId="16645" CreationDate="2015-07-06T14:47:28.497" Score="5" ViewCount="1504" Body="&lt;p&gt;How do the airlines manage the costs invovled in a codeshare? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As all airlines are selling tickets, (might be at different prices) but only one of them is operating the flight.  So, how do the airlines decide who will pay how much for the crew, fuel and catering and who will earn what?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And how do you justify:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When an airline sacrifices its capacity to other airlines as a code share partner, its operational cost will generally be reduced to nil. (&lt;a href=&quot;https://en.wikipedia.org/wiki/Codeshare_agreement#For_airlines&quot;&gt;Source:Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-07-06T18:07:20.523" LastActivityDate="2015-07-07T04:15:05.353" Title="How are the costs managed in a codeshare?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;cost&gt;&lt;commercial-operations&gt;&lt;codeshare&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16629" PostTypeId="2" ParentId="16626" CreationDate="2015-07-06T14:55:20.633" Score="3" Body="&lt;p&gt;Short answer: &lt;strong&gt;No.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: Jet engines are designed with multiple compressor and turbine discs mechanically attached to a single shaft, called a spool. Usually, there are 2 (or sometimes 3) of these spools within the engine, due to the need of the high pressure compressor and the main intake fan to spin at different speeds. Each spool spins freely and is driven by the compressed air in the engine core being pushed through the turbine stages attached to that spool. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Diagram of a Turbofan Jet Engine&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JV0ir.png&quot; alt=&quot;Jet engine diagram&quot;&gt;&#xA;Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Turbofan_operation_lbp.svg#/media/File:Turbofan_operation_lbp.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no way to &quot;shut down&quot; a particular spool. As long as the pressure in the engine core is higher than the pressure behind the nozzle, the turbines will spin and drive the spool. If you detach either one of the turbine stages or one of the compressor stages from a spool such that it 'freewheels,' the turbine discs will likely overspeed due to decreased load. Additionally, an undriven compressor stage would experience &lt;a href=&quot;https://en.wikipedia.org/?title=Compressor_stall&quot; rel=&quot;nofollow noreferrer&quot;&gt;compressor stall&lt;/a&gt;, which is essentially an &lt;a href=&quot;https://en.wikipedia.org/wiki/Stall_(fluid_mechanics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;aerodynamic stall&lt;/a&gt; of the blades of the compressor stage.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Finally, this is entirely unneeded for a couple of reasons:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, aside from the problems it would cause, there would be nothing to gain from shutting down a compressor stage. As Andy correctly mentioned in a comment, jet engines do not have a constant fuel burn per revolution, unlike piston engines. If a jet engine doesn't need to produce as much power, it can simply inject less fuel in the combustion chamber. As the pressure in the combustion chamber drops, the spools will spin down accordingly on their own (due to less pressure driving the turbine stages.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the power output profiles of jet aircraft operation are nothing like those of a car. For a car, high engine power is usually used only in brief spurts for acceleration and cruise uses a small fraction of that amount of power. In a jet airplane, on the other hand, the engines will be operated at a rather high percentage of their maximum RPMs for most of the flight. This is because additional power allows them to fly higher, which actually increases efficiency. See the answers to the previous question &lt;a href=&quot;https://aviation.stackexchange.com/q/7437/755&quot;&gt;How far can a 777 fly with just one engine at altitude?&lt;/a&gt; Unlike a car, significantly reducing the power during cruise flight actually &lt;em&gt;reduces&lt;/em&gt; the fuel efficiency of an airliner.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-07-06T15:27:40.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16630" PostTypeId="1" AcceptedAnswerId="16634" CreationDate="2015-07-06T14:59:29.720" Score="7" ViewCount="858" Body="&lt;p&gt;What are the specific problems in modern jet airliner cockpits or in piloting operations that would prevent a person with any type or severity of color blindness from completing his/her job to the same degree as a pilot without color blindness?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a follow up, are modern airliners designed to allow for pilots who have any type or severity of color blindness in case regulations change to allow them to work?&lt;/p&gt;&#xA;" OwnerUserId="9240" LastEditorUserId="1696" LastEditDate="2016-07-05T19:28:54.663" LastActivityDate="2016-07-05T19:28:54.663" Title="In what ways is color blindness an issue in modern jet airliners?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16631" PostTypeId="2" ParentId="16626" CreationDate="2015-07-06T15:13:27.410" Score="2" Body="&lt;p&gt;If you extend the idea of &quot;switch off&quot; a bit, this is already done in several different ways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surveillance aircraft may be designed to loiter over their target area with some engines shut down completely. That is not just a matter of shutting down the engines - for example if you are going to loiter at high altitude for several hours at temperatures below -50C, you are likely to need special systems to heat the oil in the shut-down engines, to avoid damage when you restart them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many jet engines contain variable stator vanes in the compressors, which are automatically adjusted to improve the efficiency under different working conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In multi-shaft engines, the relative speeds of the different shafts changes depending on the working conditions. That is more efficient that forcing all the compressor and turbine stages to run at the same speed on a single shaft. In a multi-shaft turbofan, the bypass ratio (i.e. the fraction of the air being compressed in the core engine and used for combustion, rather than just being blown by the fan to generate thrust) will also change.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-07-06T15:13:27.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16632" PostTypeId="2" ParentId="16626" CreationDate="2015-07-06T15:18:08.413" Score="9" Body="&lt;p&gt;&lt;strong&gt;Can it be done?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Has it been done?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wait, what?! Where what how?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J58&quot;&gt;Pratt and Whitney J58&lt;/a&gt; was designed to allow partial shutdown of the compressor. It does this by placing a distinctive spike in front of the compressor assembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the purpose of the transition to ramjet that is distinctive of the J58 was to allow it to avoid overheating the turbine during supersonic flight, where the increased inlet velocity translated to additional heating of the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However this does not increase the efficiency of the jet engine at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall you actually want as many stages as possible for subsonic flight. This is because multiple stages allow the gas to compress/expand more adiabatically, leading to better Carnot efficiency.&lt;/p&gt;&#xA;" OwnerUserId="600" LastActivityDate="2015-07-06T15:18:08.413" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16633" PostTypeId="2" ParentId="16630" CreationDate="2015-07-06T15:26:48.430" Score="2" Body="&lt;p&gt;I believe the answer largely lies with history. Aircraft position indicators are red/green; airports can have white and green beacons at night. Being color-blind was a disadvantage in the past. Cockpit designers use color intentionally to help get a pilot's attention. I doubt any airline wants to go to court after an accident knowing they had a color-blind pilot involved. If there was an incredible shortage of pilots they might consider arguing for relaxed standards, but they have little incentive to do so currently, as far as I can see.&lt;/p&gt;&#xA;" OwnerUserId="9227" LastActivityDate="2015-07-06T15:26:48.430" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16634" PostTypeId="2" ParentId="16630" CreationDate="2015-07-06T16:00:50.717" Score="7" Body="&lt;p&gt;There are lots of problems.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Sight is just generally important when flying. Even in airliners, most approaches are still flown manually and often visually. Any significant degradation of sight is going to be a problem when flying any type of airplane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Red/Green/White &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_light_signals&quot;&gt;light signals&lt;/a&gt; are used by air traffic control in the event of a radio failure. The inability to differentiate red from green in this case would be an enormous safety hazard (e.g. did tower just clear me to land or tell me to keep circling?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Precision_approach_path_indicator&quot;&gt;PAPI&lt;/a&gt;/&lt;a href=&quot;https://en.wikipedia.org/wiki/Visual_approach_slope_indicator&quot;&gt;VASI&lt;/a&gt; lights use colors to indicate whether you're above, below, or on the proper glide slope for a runway. While it's possible to land without them, it's a significant reduction in safety.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Lights at airports are color-coded to indicate whether a particular road is a runway or taxiway, how close you are to the end of the runway, that a runway is in use, etc. Landing on a taxiway is usually a bad idea, so it's best if you can tell the difference.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The navigation lights on airplanes themselves are color-coded. The right wingtip has a green light, the left wingtip has a red light, and the back has a white light. This lets other pilots easily determine which way you're going and, in case of conflict, who should yield (seeing a red light on another aircraft means that they're to your right and, therefore, you should yield to [i.e. divert around] them.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Colors are used on aviation charts to indicate all kinds of things, including class of airspace, type of special-use airspace, whether a field is controlled or not, type of route, elevation of terrain, where you should expect to see city lights at night, etc. You need to be able to distinguish these things quickly and accurately, even in low-light conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some cockpit instruments use colors to indicate various things. These include color bands on airspeed indicators, color of annunciator lights or their on-screen equivalents (i.e. red for warning, amber for caution, green for gear down, etc.,) echo intensity on a weather radar display, etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-07-06T16:00:50.717" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16635" PostTypeId="1" AcceptedAnswerId="16642" CreationDate="2015-07-06T16:50:12.050" Score="10" ViewCount="4172" Body="&lt;p&gt;Would a very small airfield or airstrip be considered to be a 'terminal' and have Automatic Terminal Information Service (ATIS)? Or would it just have minor weather reporting?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As in, would it make sense to provide ATIS (Automatic 'Terminal' Information Service) for a very minor airstrip? How does an airstrip qualify as being a 'terminal' to require those services?&lt;/p&gt;&#xA;" OwnerUserId="9180" LastEditorUserId="572" LastEditDate="2015-07-07T11:48:22.783" LastActivityDate="2015-07-23T19:16:39.687" Title="Do small airfields provide ATIS? If not, what weather reporting service is available?" Tags="&lt;airport&gt;&lt;weather&gt;&lt;atis&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16636" PostTypeId="2" ParentId="16635" CreationDate="2015-07-06T17:06:13.867" Score="5" Body="&lt;p&gt;No, small airports almost never have &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATIS&lt;/a&gt;. Many do, however, have an &lt;a href=&quot;https://en.wikipedia.org/wiki/Automated_airport_weather_station&quot; rel=&quot;nofollow noreferrer&quot;&gt;AWOS or ASOS&lt;/a&gt;. However, this is also not a requirement and many very small and/or private fields don't have any weather reporting at all. If any such system is present, its radio broadcast frequency will be listed on the sectional charts. When no weather reporting service is available at a particular airfield (either due to there not being one there or it being out-of-service,) pilots will generally just tune in to the weather reporting frequency of another nearby airport that is likely to have sufficiently similar weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The word 'terminal' is used in aviation to describe any type of airfield, regardless of its size. However, the presence of the word 'terminal' in the name for ATIS is not meant to imply that all terminals have ATIS, but only that all ATIS's are associated with a terminal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AWOS (Automated Weather Observing System) and ASOS (Automated Surface Observing System) systems, as their names imply, automatically monitor local weather conditions. They then produce a computer-generated voice that plays this information in a loop on a radio frequency that will be stated in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airport/Facility_Directory&quot; rel=&quot;nofollow noreferrer&quot;&gt;A/FD&lt;/a&gt; entry for the airport and listed on the sectional charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATIS includes weather information like an AWOS or ASOS, but also includes information about the airport itself, such as which runway(s) are active, which approaches are available, and anything else the local air traffic controllers want pilots to know before they contact ATC. This is not needed at small airports because they don't have air traffic controllers and pilots just choose which runway they're going to use based on current traffic and weather conditions and tell each other about it on the radio. It's also not present at some smaller airports that do have towers because the controller workload is low enough already that it isn't needed. At larger airports, though, having ATIS available helps to prevent controllers from having to waste time repeating the same information to every single pilot approaching the airport and also helps to free up the radio frequencies used by the controllers, allowing pilots and controllers to relay information to each other more quickly and efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Livingston Municipal Airport is a small airport near where I live that has an AWOS-3 transmitting on 126.175 MHz:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/tW9pG.png&quot; alt=&quot;Livingston Sectional Chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The smaller nearby Jackson County Airport, however, has no weather observation facilities. Aircraft approaching this airport would probably just listen to the weather report from Livingston or another nearby airport:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/KLlN6.png&quot; alt=&quot;Jackson Co Sectional Chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The much larger nearby Nashville International Airport does have ATIS service operating on 135.1 MHz:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/8PANb.jpg&quot; alt=&quot;BNA Sectional Chart&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-07-07T05:41:10.083" LastActivityDate="2015-07-07T05:41:10.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16638" PostTypeId="1" AcceptedAnswerId="16640" CreationDate="2015-07-06T17:35:21.937" Score="5" ViewCount="8050" Body="&lt;p&gt;Suppose that you have to connect two destinations like Phoenix and Anchorage, which are 5850km apart. Now, you have two choices: to either fly over the land, or completely fly over Bering Sea (Arctic Ocean). So, what would be the better route to choose? Currently, the route is partially over the sea and partially over the land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, this is just a case, in general out of land and sea, which route is preferred? One common argument is that you are safer by flying over land in case of an emergency, but are there any aerodynamic concerns also involved?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="167" LastEditDate="2015-07-07T02:05:44.780" LastActivityDate="2016-08-24T11:21:43.457" Title="Between land and sea, which route is preferred?" Tags="&lt;flight-planning&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16639" PostTypeId="2" ParentId="16612" CreationDate="2015-07-06T18:02:56.213" Score="7" Body="&lt;p&gt;Here's Peter's diagram with two different airspeeds, so you can see the difference in the vertical speed:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/9pMJX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-06T18:02:56.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16640" PostTypeId="2" ParentId="16638" CreationDate="2015-07-06T18:10:49.307" Score="10" Body="&lt;p&gt;The ususally preferred path will be the shortest, as any additional km flown will require extra fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the example you propose we can look at what companies actually do (US653 of 5 July 2015):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XzcWQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can observe they fly pretty close to the great circle passing through the two airports, meaning that they will fly partially over the ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This poses no additional risks, as the shoreline is never really far away and in case of emergency an alternate airport will most likely always be within reach.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-07-06T18:10:49.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16641" PostTypeId="2" ParentId="16612" CreationDate="2015-07-06T20:05:16.427" Score="5" Body="&lt;p&gt;The other answers handle the question very basically. If a plane is moving through the air in the direction of its nose, and that nose happens to be pointed toward the ground, then the faster the plane is moving through the air in the direction of its nose, the faster it will descend. This is simple trigonometry; the plane's &quot;true airspeed&quot; is the hypotenuse of a triangle, the other two legs being the pure horizontal and vertical components of that airspeed, namely the plane's &quot;ground speed&quot; and its &quot;vertical speed&quot; (aka climb/descent rate). At a constant angle of climb or descent, if you increase your airspeed, you will increase your ground speed and your vertical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another, more realistic way to think of it is the other way around; all other things being equal, when an aircraft's descent rate increases, its speed increases. This is due to physics, and the conversion of energy between potential and kinetic forms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple non-aircraft example. Say you have a sandbag with a rope tied around it and fed through a pulley overhead. By pulling on the rope, you lift the sandbag against the force of gravity by a certain amount. You expend energy to do this, and are storing some of that energy (ideally, all of it, but in the real world there are &quot;inefficiencies&quot;) in the weight inherent in its height above the ground. Release the weight, and gravity accelerates it by a time-dependent (and thus height-dependent) amount, so that by the time it hits the ground, all the potential energy you stored by hoisting the weight has been converted to kinetic energy of motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This same basic relationship also exists in aircraft; an aircraft stores energy expended by its engine (or in a glider, by the engine of a tow craft) in its altitude. The aircraft can then reduce its altitude to maintain (or in a true dive, even gain) forward airspeed. This is one of the most basic principles of aerobatics and is taught to all pilots; you can &quot;trade altitude for airspeed&quot;, whenever you need more (or less) of one and have enough of the other to give up (or gain). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanisms by which this happens can be made as complex and esoteric as you want to get; we can cover the four fundamental forces of flight and how different forces act in different directions depending on the attitude of the aircraft and thus contribute different horizontal and vertical subcomponents to the aircraft's motion relative to its nose or the ground under it. But, to answer this question it is enough simply to state that as a plane descends, it is trading its altitude to gain energy, and the amount of that energy not lost to drag will increase the plane's forward airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This feeds back into the original answer. As you descend from altitude, your forward airspeed (the speed of travel in the direction of the plane's nose) will increase as potential energy is converted to kinetic. Because that forward airspeed is in a downward direction, as long as drag is not keeping acceleration in check (such as with a higher angle of attack, which increases drag by increasing the &quot;cross section&quot; of the wings directly exposed to airflow), it creates a feedback loop; you descend, gaining airspeed, which causes you to descend faster, gaining more airspeed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To counteract this, descending airliners often reduce engine power (so the energy gained by descending merely offsets the decrease in thrust), increase their angle of attack (if the aircraft is travelling along a path &quot;beneath&quot; its nose, the wings are more &quot;side-on&quot; to the airflow moving past them which increases drag) and deploy spoilers or air brakes (which directly increase drag even at low angles of attack).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-06T20:10:24.617" LastActivityDate="2015-07-06T20:10:24.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16642" PostTypeId="2" ParentId="16635" CreationDate="2015-07-06T22:38:46.690" Score="9" Body="&lt;p&gt;There is no minimum definition of a &quot;terminal&quot; in and of itself. The &quot;destination terminal&quot; of a flight is simply its planned endpoint. That's usually, but not always, a man-made complex designed to facilitate human flight, which we call an airport. However, you can file a VFR flight plan to fly out to a friend's fallow field in BFE, miles from any airfield listed on a sectional:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/REJOh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/REJOh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's then your responsibility, as it always is in VFR, to ensure you can operate the plane safely at all times, including getting the plane on the ground and then back up in the air without causing personal injury, property damage, infringing private property rights, violating noise ordinances, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sectional diagrams use the term &quot;airport&quot; to refer to any place that is registered with the FAA to be used for the purpose of aircraft takeoffs and landings. These places may be more specifically called airstrips, airfields, air parks, aerodromes etc to indicate relative size, construction, ownership or facilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only requirements for an airport to be documented by the FAA and appear on a sectional are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The location must meet minimum guidelines specified in the Airport Certification Manual, including land grading for smoothness and drainage, obstruction/obstacle clearance in three dimensions, and minimum safety markings and wind/traffic pattern indicators that are necessary to support aircraft takeoffs/landings at the location (really the only thing every airport requires along these lines is a windsock; everything else is provided as needed for the specific location or as desired by the field's users). This usually requires a minimum amount of maintenance/upkeep by its owner for the purpose, even if it's just a grass field (it would have to be regularly mown and weeded to remove certain spiky or wood-stemmed plants, for instance).&lt;/li&gt;&#xA;&lt;li&gt;The location must be registered with the FAA by its owner/manager for this purpose (they can register it as a reserved/private airfield, and then only limited information will be given on the sectional, primarily as an advisory that the location is available for emergency landings).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's all there is to it. Besides a windsock which is the absolute minimum, no minimum facilities must exist; even the traffic pattern/landing direction indicators are optional if traffic can always use a left-hand pattern and determine the runway approach from the windsock. Rhome Meadows Airport (T76) between Fort Worth and Decatur, TX is a grass strip, with no lights, no tower, no fuel, no hangars, and the displaced threshold on the south end is marked with two white painted tires (no threshold markings to the north). Nearby Heritage Creek Airstrip is only slightly better, with low-intensity runway edge lights. Despite this, both are fairly active for unimproved strips, with about nine flights a day involving each one in some way (TO/L, T&amp;amp;G).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the airport section of the legend for FAA sectionals:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/H9HDk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that there's a wide array of symbology available to indicate at a glance what the facility offers; control tower or no, length and configuration of hard surface runways if any, usage type, presence of FBOs for fuel/maintenance, navigational aids, and radio information including ATIS, AWOS, ASOS, control towers, UNICOM etc. Obviously a control tower needs a radio frequency, but there is no requirement that a towered facility have ATIS. ATIS is usually found at towered airports as its purpose is to reduce controller workload, but nontowered airports can have ASOS/AWOS stations which provide practically the same information regarding weather, without the superfluous runway information (at nontowered airports, the pilots usually determine the approach/departure direction). If an airport has no reporting whatsoever, you would usually tune to the nearest listed AWOS/ASOS.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T19:16:39.687" LastActivityDate="2015-07-23T19:16:39.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16643" PostTypeId="1" AcceptedAnswerId="16652" CreationDate="2015-07-07T01:56:07.640" Score="12" ViewCount="9937" Body="&lt;p&gt;I'm learning about radionavigation, and all the various analog displays that can be used:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Automatic Direction Finder (ADF) - Provides basic bearing information to practically any radio source the pilot can tune to. Designed for use with the older NDB system developed during WWII, still in use but about two generations redundant in the face of VOR and GPS. Later models include a manual compass card to reduce mental math.&lt;/li&gt;&#xA;&lt;li&gt;Radio-Magnetic Indicator (RMI) - A two-channel ADF with compass card slaved to the magnetic compass (or in some cases using an internal gyro like the Heading Indicator).&lt;/li&gt;&#xA;&lt;li&gt;Omni Bearing Indicator (OBI) - Used for VOR navigation and the cheapest way to do so, has a manual compass card that selects the desired VOR radial and a CDI needle to provide a steering aid to place the aircraft on that radial, with a &quot;TO/FROM&quot; indicator to resolve directional ambiguity.&lt;/li&gt;&#xA;&lt;li&gt;Horizontal Situation Indicator (HSI) - Combines the OBI with the aircraft's gyroscopic direction indicator to provide a simplified &quot;moving map&quot;, with the aircraft's current heading, relative direction of the selected VOR radial, course deviation and glide slope all in one instrument. Can replace the Heading Indicator as well as an OBI to reduce instrument count and/or allow for redundant backups like a second artificial horizon. Biggest downside is cost (about $13k for the display unit itself).&lt;/li&gt;&#xA;&lt;li&gt;Distance Measuring Equipment (DME) - essentially IFF in reverse; the aircraft interrogates a ground station with radio pulse pairs, and the station sends a matching pulse pair after a specially-timed delay; total round-trip time of the interrogation and response, minus the preprogrammed delay and halved, is the time the signal took to reach the station at the speed of light through air (about one nmi in 12.36 microseconds), which can then be used to calculate distance. These transponders are often colocated with NDB or VOR stations on a corresponding frequency allowing aircraft to get an accurate fix from a single ground station.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My understanding is that, for an aircraft to be suitable for IFR flight, the aircraft requires all VFR instruments (airspeed, altitude, compass, tach, oil pressure, oil or coolant temp, fuel gauge) plus a timepiece, gyroscopic direction indicator, Turn Coordinator or Turn/Slip Indicator, adjustable pressure altimeter, artificial horizon, and &quot;&lt;strong&gt;two-way radio communication and navigation equipment suitable for the route to be flown&lt;/strong&gt;&quot;, that last requirement being just wonderfully ambiguous regarding what you as a pilot may want or need from the above listed equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard configuration for the 172 and Cherokee seems to be two OBIs, one with glide slope and one without, plus a single-channel ADF. This seems like a fairly economical gauge cluster for modern radionavigation, but the ADF seems old-fashioned in the face of the newer RMI that allows triangulation from an ADF and a VOR or two VORs more or less at a glance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the very newest and most expensive aircraft have full glass cockpits, but for the rest of us, what displays are typically used? Do people tend to upgrade the ADI to an RMI, or is that the display that's considered redundant with NDBs on their way to retirement? How many people spring for the HSI? Do you keep the non-GS OBI if you have an HSI, or do you replace that with something else too? Is DME standard equipment, can't fly without it, or do pilots more often rely on multi-station triangulation for a position fix?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-07T21:00:09.940" LastActivityDate="2018-05-09T18:25:58.443" Title="OBI, RMI, HSI... What combination do GA aircraft w/o glass typically have?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16644" PostTypeId="2" ParentId="16638" CreationDate="2015-07-07T02:16:13.817" Score="13" Body="&lt;p&gt;At the cruising altitude of most airliners, there is no noticeable aerodynamic difference between being over land or over sea. At lower levels, being over sea would typically offer less turbulence, in part because as the ground warms you can encounter rising air thermals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, airliners fly whatever route provides the shortest &lt;em&gt;time&lt;/em&gt;, which is not always the shortest &lt;em&gt;distance,&lt;/em&gt; often called the Great Circle route. The GC route is not always quickest because of jetstream winds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to consider when choosing between an over-land or over-sea route is the distance to another airport should an engine fail. You might have heard of ETOPS. Basically, twin engined aircraft must fly within a certain distance of a suitable landing site - often 2 or 3 hours of flying time on one engine. In the middle of the ocean the quickest route may take the aircraft outside of this range, so it will have to fly closer to land, or even in certain remote parts of the world, still over land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another consideration is life rafts. They are legally required when flying more than 25 miles (if I recall correctly) out to sea. Life rafts add weight and therefore cost so some airlines have actually &lt;a href=&quot;http://www.theguardian.com/business/2014/may/23/qantas-plan-to-remove-life-rafts-is-in-line-with-global-standards&quot;&gt;removed life rafts from their aircraft&lt;/a&gt;, or at least only have a few of their jets allocated for flights over water. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-07-07T02:16:13.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16645" PostTypeId="2" ParentId="16628" CreationDate="2015-07-07T04:15:05.353" Score="1" Body="&lt;p&gt;As the wikipedia article clearly states, there are several types of Codeshare Agreements : &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Block space codeshare: A commercial (marketing) airline purchases a&#xA;  fixed number of seats from the administrating (operating/prime)&#xA;  carrier. A fixed price is typically paid, and the seats are kept away&#xA;  from the Administrating carrier's own inventory. The marketing airline&#xA;  decides on their own which booking classes the seats are sold in (the&#xA;  block of seats are optimised just like another aircraft cabin).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Free flow codeshare: The airlines' inventory and reservation systems&#xA;  communicate in real-time by messaging, commonly IATA AIRIMP/PADIS&#xA;  messaging (TTY and EDIFACT). A booking class mapping is defined&#xA;  between the airlines. No seats are locked to any of the airlines, and&#xA;  any airline can sell any number of seats.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Capped free flow: Basically the same as above, but a capping (max&#xA;  number of seats) are defined for each of the marketing airlines&#xA;  participating in the codeshare with the Administrating&#xA;  (operating/prime) carrier.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In these cases, profitability of the Airline Marketing the other airline's tickets is possible in any of the following ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;There might be an agreement with the Carrier Airlines where the Marketing Airline gets to sell the tickets at the same rate as being sold by the Carrier Airline,but the Carrier Airline sells the tickets to the Marketing Airline at lower prices. This helps the Marketing Airline to generate revenue and improve its indicated (apparent) frequency on the given route. The Carrier Airline is benefited in a way where its tickets are sold on more than one portals, so better visibility (Marketing) and hence the name.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Now a days alliances like &lt;a href=&quot;http://www.oneworld.com/member-airlines/overview&quot; rel=&quot;nofollow&quot;&gt;OneWorld&lt;/a&gt; are being formed, where multiple carriers come together and form codeshare bases to mutually benefit each other.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Marketing Airline might even sell the tickets at a cheaper price than the original Carrier Airline, just to establish its base in the route before starting its operations, so that when it starts its operations, people already know about it. hence, without deploying planes for the route, it can already have an established consumer base.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-07T04:15:05.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16646" PostTypeId="2" ParentId="16080" CreationDate="2015-07-07T04:22:23.043" Score="5" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Self-sealing_fuel_tank&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; wikipedia article :&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Most jet fighters and all US military rotary wing aircraft have some type of self-sealing tanks. Military rotary wing fuel tanks have the&#xA;additional feature of being crashworthy. High altitudes require the&#xA;tanks to be pressurized, making self-sealing difficult. Newer&#xA;technologies have brought advances like inert foam-filled tanks to&#xA;prevent detonation. This foam is an open cell foam that effectively&#xA;divides the gas space above the remaining fuel into thousands of small&#xA;spaces, none of which contain sufficient vapour to support combustion.&#xA;This foam also serves to reduce fuel slosh. Major manufacturers of&#xA;this technology include Hutchinson, Amfuel (Zodiac) (formerly&#xA;Firestone), Meggitt (formerly Goodyear), Robertson Fuel Systems, GKN&#xA;USA and FPT Industries. FPT is now part of GKN. For military use,&#xA;tanks are qualified to MIL-DTL-27422 (includes crashworthiness&#xA;requirements) or MIL-DTL-5578 (non-crashworthy). An aircraft fuel tank&#xA;sometimes consists of several interconnected fuel cells. The&#xA;interconnecting hoses are typically also self-sealing.&lt;/p&gt;&#xA;&lt;p&gt;In addition to fighter aircraft some military patrol vehicles and&#xA;armoured VIP limousines feature self-sealing fuel tanks.&lt;/p&gt;&#xA;&lt;p&gt;Self-sealing fuel tanks using military technology are also required in some motorsport categories.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Given the fact anti explosion tanks were invented in 1917, and are in use since then, and have undergone many technological advances since then, they are being used quite commonly and in most of the planes where pressurization is required.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-07T04:22:23.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16647" PostTypeId="2" ParentId="15140" CreationDate="2015-07-07T04:35:55.920" Score="0" Body="&lt;p&gt;According to this &lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/airbus-lights-the-way-first-a321-with-led-lighting-throughout-the-cabin/&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt;, an Airbus A-321 has around 100 LED units for cabin lighting which have 45 individual diodes each. Do you have 4500 diodes in the cabin in a single aisle plane, which means at 0.05W per LED estimation, the cabin lighting would require 225 W of power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;p.s. This does not include reading lamps (most probably) and only the aisle lighting.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-07T04:35:55.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16649" PostTypeId="1" AcceptedAnswerId="16653" CreationDate="2015-07-07T04:56:25.930" Score="10" ViewCount="2132" Body="&lt;p&gt;In the FAA AFD for Santa Rosa airport (KSTS), the pattern altitude is given as 1,000’ AGL for small aircraft, and 1,500’ AGL for large aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do these altitudes differ? Doesn’t it compromise having a uniform pattern altitude so aircraft can see each other?&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-07-10T00:58:22.137" Title="Why have different pattern altitudes for different aircraft?" Tags="&lt;traffic-pattern&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16650" PostTypeId="2" ParentId="16560" CreationDate="2015-07-07T04:58:18.730" Score="14" Body="&lt;p&gt;Most decidedly not, at least not for the first fly-by-wire fighter in the NATO arsenal, the F-16. Its stick, in initial block versions, did not move at all, instead using piezoelectric load cells to detect stick pressure. This caused some issues with novice Viper drivers overreacting to the stiffness of the controls compared to anything they had flown and overrotating the jet on takeoff, smacking the turkey feathers on the ground. Later blocks put a little play in the stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the Tomcat being an easy plane to fly, &lt;em&gt;Top Gun&lt;/em&gt; kind of over-romanticized it. The TF30 engine initially put into these aircraft was underpowered and terribly unreliable (one thing the movie did get right is that the engines were prone to compressor stalls when encountering disturbed air such as jetwash or even their own missile launch trails). The aircraft itself, while a big improvement in dogfighting over the F-4, was still big and heavy, the result of requirements that it be a long-range supersonic interceptor in an era without supercruise or the relatively light AMRAAM missile; the aircraft instead had to be able to haul a full load of AIM-54 Phoenix missiles intended for the ill-fated naval variant of the F-111, along with the large, complex radar system to lock on and fire them, and a boatload of fuel to get all that out to patrol range and back. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Navy's initial mixed results with the F-14A, along with the extremely high costs of the aircraft ($32 million each at the height of production) and the lack of ground attack capabilities, were mirrored in the USAF with its F-15 program; the looming retirement of the F-4 was about to leave both branches without a fighter capable of the Phantom's multi-mission capability, and both the F-14 and F-15 were big expensive interceptor-style pure air-to-air fighters, which some Air Force brass believed was proof that nothing had been learned from Vietnam. The USAF commissioned the Light Weight Fighter competition, which produced the F-16, a light, relatively inexpensive multirole fighter that has become one of the most successful land-based fighter jets in history. The Navy preferred some traits in the USAF's losing aircraft, the YF-17, such as the twin-engine design for durability, and it would go on to develop this design into one of the most successful &lt;em&gt;naval&lt;/em&gt; aircraft of all time, the F/A-18 Hornet and Super Hornet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tomcat eventually lived up to its promises with some engine and avionics upgrades (including a hybrid-FBW system and a LANTIRN pod to add air to ground smart bomb capabilities) but the aircraft was by no means a perfect plane or a dream to fly.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-11-10T18:32:06.567" LastActivityDate="2015-11-10T18:32:06.567" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16651" PostTypeId="2" ParentId="16649" CreationDate="2015-07-07T05:07:01.467" Score="7" Body="&lt;p&gt;Larger aircraft generally are faster and fly wider patterns than small planes. It would be much more difficult to sequence different types of aircraft at the same altitude while maintaining separation. &lt;/p&gt;&#xA;" OwnerUserId="9248" LastActivityDate="2015-07-07T05:07:01.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16652" PostTypeId="2" ParentId="16643" CreationDate="2015-07-07T05:46:47.890" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;two-way radio communication and navigation equipment suitable for the route to be flown&quot;, that last requirement being just wonderfully ambiguous regarding what you as a pilot may want or need …&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That statement isn't ambiguous at all. You can file and fly IFR with a transponder and a VHF comm radio if you can get controllers to issue you radar vectors for the route -- just be making a visual approach at your destination (or something like an &lt;a href=&quot;https://en.wikipedia.org/wiki/Surveillance_radar_approach&quot; rel=&quot;noreferrer&quot;&gt;ASR or PAR approach&lt;/a&gt; where you get your guidance from a controller).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course since your question was not &quot;How do I piss off ATC?&quot; that's neither here nor there - you're asking about typical instrument configurations in GA aircraft (for purposes of this answer I'm going to assume you mean the usual &quot;Light GA / trainer&quot; sort of aircraft - typical Pipers, Cessnas, Beechcraft, Mooneys, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to nail down &quot;typical&quot; because it's a rapidly moving target these days. When I started flight training two Nav/Com radios and an ADF was a pretty sweet IFR airplane, even if the ADF was a little sketchy. Now even a six-pack cockpit has a good chunk of glass in the panel in the form of a GPS (Garmin 430 or similar), and people are ripping out ADFs as the FAA decommissions them, but I poked around at some of the rental fleets near me  and it seems to shake out like this as of right now:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Most IFR aircraft have dual OBIs. If there's a GPS they tend to both have glideslope capability (either connected to two GPS Nav/Coms or one to the GPS and one to a traditional Nav/Com radio that has a glideslope receiver).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Older planes with dual Nav/Comm radios often have glideslope capability on the #1 Nav/Com &amp;amp; not the #2 radio, which is why you often see one OBI with a glideslope needle and one without.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Older IFR trainers tend to have ADFs still. Some are placarded as &lt;code&gt;INOP&lt;/code&gt; and are basically heavy, drag-producing AM Radios (the Mets won).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft with a GPS rarely have an ADF, because the GPS can usually display the ADF indications using a &quot;normal&quot; OBI. One less thing for the pilot to have to remember how to operate.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I've never seen a light GA aircraft with an RMI.&lt;br&gt;&#xA;They're probably out there but I doubt they're common. Slaving them to the magnetic compass requires equipment which is not cheap, and as ADFs are dying out there's not much benefit to installing one now.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;None have HSIs, but I have seen a few planes around with them.&lt;br&gt;&#xA;My sense here is it tends to be an owner-installed upgrade because the pilot wants it and they have the money to spend on it. Like you noted they're still pretty expensive, mainly because they're rather complicated bits of equipment combining a vacuum-powered DG, a bunch of sensors, and a VOR/LOC/GS presentation.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Every HSI installation I've seen takes the place of the Nav 1 OBI.&lt;br&gt;&#xA;What gets put into the now-vacant hole varies from aircraft to aircraft. &lt;a href=&quot;https://i.stack.imgur.com/nOObR.jpg&quot; rel=&quot;noreferrer&quot;&gt;This Cessna has an ADF card there&lt;/a&gt; (thanks to &lt;a href=&quot;http://www.cfcmss.org/CongressionalFlyingClub/Planes/CessnaSkylane182Q(N5244N).aspx&quot; rel=&quot;noreferrer&quot;&gt;CFC&lt;/a&gt; for the photo)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Very few have DME.&lt;br&gt;&#xA;If you're flying on Victor airways you're pretty much always flying toward some VOR (so you have one needle that won't move), and you can easily get a cross-bearing from a VOR that would be roughly perpendicular to your route to find your current position on the chart.&lt;br&gt;&#xA;The DME gives you this in Distance/Direction form without needing to tune a second VOR or draw on your chart, and it can do nice things like give you an approximate groundspeed, but that doesn't make it indispensable.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A reason many IFR trainers lack a DME seems to be because on the IFR checkride you can't be tested on equipment that's not installed: If you have no DME you can't be asked to fly a DME arc.&lt;/li&gt;&#xA;&lt;li&gt;DME is another technology that's being made redundant by GPS: The GPS can give you distance and bearing to any arbitrary point, and that point can easily be a VOR. It can also compute groundspeed.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;An ever-increasing number have large chunks of glass somewhere in the panel.&lt;br&gt;&#xA;As GPS installations become more common it's increasingly rare to find a plane &lt;em&gt;without&lt;/em&gt; a moving map display next to the six pack. The GPS provides the magic &quot;Magenta Line&quot; and also typically feeds an OBI (or HSI).&lt;br&gt;&#xA;If the OBI or HSI fails the GPS can usually also display a digital OBI on its display.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-07T05:46:47.890" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16653" PostTypeId="2" ParentId="16649" CreationDate="2015-07-07T05:51:47.867" Score="8" Body="&lt;p&gt;Several possible reasons.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Speed differences between aircraft classes. Larger jets cruise and land at much faster speeds than single-engine props. Keeping their pattern separate from slower traffic minimizes problems posed by a faster plane entering the pattern behind a slower one.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Noise abatement. A jet, even a smaller private one at near-idle in approach, is loud. Keeping them higher increases the distance and number of thermal strata to shield nearby residents from traffic noise.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Prevailing instrument conditions and relative pilot experience levels. A ceiling below 1000 feet, the small craft pattern altitude, would ground VFR flights and thus drastically reduce the number of small craft in the first place. Jets, turboprops and other larger planes are much more likely to be IFR-capable (plane and pilot) and so they're placed higher because they can deal with clouds in the pattern (the airport, if towered, would likely alter pattern height to clear cloud layers but traffic holding above the clouds would still require an IFR approach).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-07T15:38:01.413" LastActivityDate="2015-07-07T15:38:01.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16654" PostTypeId="1" AcceptedAnswerId="16656" CreationDate="2015-07-07T06:46:23.710" Score="10" ViewCount="9759" Body="&lt;p&gt;Rudder is usually used to maintain coordinated flight. When banking to one side to begin a turn, the rudder is usually pushed towards that side. I guess this is still valid in inverted flight: in normal flight, if the pilot bank the plane to the right, it also push the right pedal (to conteract adverse yaw); in inverted flight, if the pilot bank to the right, the plane will turn to the right seen from the ground, i.e. the left seen from the pilot. The pilot should apply left rudder to keep coordinated flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot want to make a aileron roll, what will be the general action on rudder given the flight goes quickly from normal to inverted and back to normal, and the pilot don't want to initiate a turn?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2015-07-07T15:58:45.410" LastActivityDate="2018-09-28T16:17:30.260" Title="How is rudder used in a aileron roll?" Tags="&lt;aerobatics&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16655" PostTypeId="2" ParentId="16654" CreationDate="2015-07-07T07:47:12.433" Score="5" Body="&lt;p&gt;Well first, by barrel roll do you mean a true barrel roll which is a combination loop and roll, or do you mean a tighter maneuver like an aileron roll or slow roll accomplished mainly with ailerons but which can still result in a rotation around a point above the plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer in all three cases is that rudder is used to help maintain stability in the roll. A little rudder at just the right time can help keep the nose up in a slow roll or even an aileron roll, as the plane rotates through the sideways portions of the roll when gravity is otherwise not countered. Counter-rudder (applying rudder opposite to a bank) can also help to start a &quot;wide&quot; roll by kicking the plane into an initial yaw that counters the tendency of the plane to turn into the initial bank. Finally, first a hard left yaw and then a hard right yaw is used to execute a &quot;true&quot; barrel roll where the plane rolls in a circle roughly perpendicular to its original path.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-07T07:47:12.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16656" PostTypeId="2" ParentId="16654" CreationDate="2015-07-07T09:10:40.807" Score="12" Body="&lt;p&gt;The key in flying a good roll is to keep the aircraft's nose up in anticipation of the lift requirement when flying in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12383/can-you-fly-an-airplane-at-a-90%C2%B0-roll-angle-without-losing-altitude/12386#12386&quot;&gt;knife-edge&lt;/a&gt; or &lt;a href=&quot;https://aviation.stackexchange.com/questions/5200/what-was-the-first-aircraft-that-could-fly-inverted&quot;&gt;inverted&lt;/a&gt; flight. Since in knife-edge the elevator and rudder will assume each others function, you will need rudder as well as elevator for directional and pitch control. Also, depending on adverse yaw, some rudder is required to hold yaw to zero when applying ailerons. The procedure is as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Speed up, so you are fast enough for roll maneuvering and inverted flight.&lt;/li&gt;&#xA;&lt;li&gt;Pitch up a few degrees. How much depends on wing incidence and zero-lift angle of attack. Look out for some feature on the horizon: This will help you to keep your direction constant. &lt;/li&gt;&#xA;&lt;li&gt;Stop the pitching motion, then apply full ailerons. Correct the aileron-induced yawing motion by applying gentle rudder (trailing edge in the direction of the up-going aileron). Your goal is to keep the fuselage pointing at the chosen feature throughout the maneuver.&lt;/li&gt;&#xA;&lt;li&gt;With increasing roll angle, apply rudder to keep the nose up. At the same time, push the stick gently to avoid course deviation. At 90° roll angle, both elevator and rudder have changed their function: The elevator will now control direction, and the rudder will control pitch.&lt;/li&gt;&#xA;&lt;li&gt;Keep the rotation rate and push the stick more when changing from 90° to 180° roll angle. In inverted flight you need to keep the aircraft trimmed, and depending on the static stability and speed this can require considerable negative elevator deflections. At the same time reduce rudder deflection such that the fuselage will still point into the initial direction. At 180° roll angle both elevator and rudder have returned to their old function, but pulling will now start a dive.&lt;/li&gt;&#xA;&lt;li&gt;On the way to 270° you will again need to add some rudder, now in the opposite direction, to keep the nose up. Again, elevator and rudder will exchange their functions.&lt;/li&gt;&#xA;&lt;li&gt;Once you return back to normal flight attitude, stop the rolling motion and reduce rudder deflection back to zero.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-07T09:10:40.807" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16657" PostTypeId="2" ParentId="16635" CreationDate="2015-07-07T10:05:18.687" Score="3" Body="&lt;p&gt;In Germany, most airfields that are equipped or certified for IFR operations will have an ATIS. In those cases were an airfield is not equipped with an ATIS, all weather information produced by the certified meteorological personnel at the airfield will be provided on the AFIS (Aerodrome Flight Information Frequency) frequency upon request.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/07NDS.png&quot; alt=&quot;EDGS AD AIP&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: AIP Germany AD EDGS)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all airfields that neither have certified meteorological personnel or equipment, the weather information will be rudimentary, such as winds only, but no QNH, precipitation or cloud observation. ASOS or AWOS are not used in Germany.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-07-07T10:05:18.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16658" PostTypeId="2" ParentId="16649" CreationDate="2015-07-07T10:12:28.783" Score="6" Body="&lt;p&gt;Additionally to &lt;a href=&quot;https://aviation.stackexchange.com/a/16653/572&quot;&gt;KeithS'&lt;/a&gt; answer, you also have some airfields in e.g. Germany, where a different pattern exists for glider aircraft, ultra-lights and regular single or multi engine pistons. The consideration here is not only speed, but also the ability to maintain level flight. Glider patterns in almost all cases will be very close to the airfields with little impact on surrounding housing areas, as gliders generally create less noise than powered aircraft. They also need to remain closer to the airfield in the pattern, as they can only trade speed vs altitude, but not gain altitude or maintain it as power aircraft. Powered aircraft can follow a pattern that will be suitable for noise abatement and other requirements, such as obstacle clearance or avoiding certain areas for other reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same consideration that apply above between gliders and powered aircraft do apply between slow powered aircraft and fast powered aircraft, as already explained in the other answer.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-07T10:12:28.783" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16659" PostTypeId="1" AcceptedAnswerId="16666" CreationDate="2015-07-07T10:38:40.480" Score="6" ViewCount="1244" Body="&lt;p&gt;I once read somewhere that pilots can go to some facilities so get trained for crashes.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I actually went to a facility in New London, CT where they actually&#xA;  dunk you in water strapped in the seat of an airplane upside down and&#xA;  with your eyes closed in a big pool.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is there any formal training for the commercial pilots to be prepared for crashes? If yes, how far do they go in training pilots and for what kind of crashes?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="572" LastEditDate="2015-07-07T11:11:49.193" LastActivityDate="2015-09-17T18:34:14.947" Title="How are pilots trained to prepare for crashes?" Tags="&lt;safety&gt;&lt;flight-training&gt;&lt;pilots&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16660" PostTypeId="1" AcceptedAnswerId="16683" CreationDate="2015-07-07T10:47:50.183" Score="2" ViewCount="3209" Body="&lt;p&gt;For commercial pilots' training, airlines rely heavily on the training at computer simulators (fixed base simulators), where one can learn the cockpit controls and how to use the cockpit displays to control the airplane. But this does not give them the physical feel of controlling the airplane (which can be felt while using a real physical simulator (Hydraulic Simulators), as used by NASA in training their astronauts). Do airlines use such physical simulators to train pilots or are computer simulators the only ones used? Moreover, what is the usefulness of simple computer simulators as such then? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a follow-up, do military pilots undergo training in physical real life simulators or they too are trained first in the computer simulators and then directly in the training planes?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2017-01-23T19:27:17.743" LastActivityDate="2017-01-23T19:27:17.743" Title="How useful are simulators in pilot training?" Tags="&lt;flight-training&gt;&lt;pilots&gt;&lt;flight-simulator&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16661" PostTypeId="1" AcceptedAnswerId="16664" CreationDate="2015-07-07T10:51:12.697" Score="4" ViewCount="2852" Body="&lt;p&gt;When an aircraft lands with the tires of the landing gear at rest, as soon as the the aircraft touches down, the landing gear experiences a large amount of &lt;strong&gt;wheel-spin up&lt;/strong&gt; forces (because of the static friction involved between the stationary tires and the relatively moving runway at a very fast speed), which even cause it to vibrate at some frequency. This force is considered to be highly undesirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are airplane manufacturers using any kind of measures to reduce these forces on the landing gear at touchdown? How are they compensated?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8079" LastEditDate="2015-07-07T15:56:18.797" LastActivityDate="2015-07-07T21:27:50.240" Title="How are forces on the landing gear reduced or compensated for at touchdown?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;landing-gear&gt;&lt;aircraft-development&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16662" PostTypeId="2" ParentId="16635" CreationDate="2015-07-07T12:29:13.903" Score="3" Body="&lt;p&gt;Airstrips provide at least a wind sock (or wind cone) to indicate direction and strength of the wind at ground level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wind sock is required to operate even the tiniest strip, and as such provides the minimum level of weather information available - provided the pilot is close enough to be able to see it clearly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specifications of this information source are discussed in the answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/8051/2176&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the FAA specification available &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/150-5345-27d/150_5345_27d.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-07T15:11:04.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16663" PostTypeId="2" ParentId="16659" CreationDate="2015-07-07T12:48:23.987" Score="6" Body="&lt;p&gt;I've seen pictures of this sort of training for helicopter underwater emergency training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://mstc.louisiana.edu/courses/opito-certified-courses/huet-cold-water-%E2%80%93-helicopter-underwater-emergency-training&quot;&gt;Training link&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is given to offshore oil rig crews, who will be passengers on the helicopters, as well as the pilots who will be flying them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As offshore crews fly so frequently in helicopters, it's worth the time giving them this sort of emergency training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never heard of it being used for fixed wing plane crews though.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2015-07-07T12:56:42.677" LastActivityDate="2015-07-07T12:56:42.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16664" PostTypeId="2" ParentId="16661" CreationDate="2015-07-07T14:16:38.240" Score="7" Body="&lt;p&gt;There are lots of forces acting on the gear at the point of landing. The best way to minimize loads on the gear is to land smooth (I know that sounds obvious). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what it's worth you do not necessarily want to spin up the gear before landing for a few reasons. First off you would need to spin up the gear to &lt;em&gt;precisely&lt;/em&gt; (or at least very close to) the speed that the plane was going to touch down at. If you spin the gear up faster you actually will create a problem by accelerating the plane when it touches down. Spinning the gear up can also have a serious &lt;a href=&quot;https://aviation.stackexchange.com/questions/3709/why-tap-the-brakes-on-take-off-in-fixed-gear-aircraft&quot;&gt;gyroscopic effect&lt;/a&gt; (since you now have a fast rotating mass) (&lt;a href=&quot;https://aviation.stackexchange.com/questions/3702/why-are-aircraft-tires-not-pre-spun-prior-to-landing-to-preserve-them/3705#3705&quot;&gt;see here as well&lt;/a&gt;) that will affect the handling of the aircraft.      &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of that remember that in aviation it's often about cost. What are the costs to maintain a system that pre-spins the gear vs the cost of tires. Some times its actually cheaper and easier to make a part that wears out some what quickly and replace it often, then design a complex system that require maintenance and up keep.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that &lt;a href=&quot;http://archives.sensorsmag.com/articles/0300/14/index.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;some devices&lt;/a&gt; for spin up have been looked into but the rotational inertia problem seems to be more of a concern than wheal wear. I would imagine that unintentional side loads on gear are a bigger issue and bigger cause of wear on the landing assembly. Keep in mind that the addition of an assembly like this also adds weight to the aircraft, and no one likes weight that is not needed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a great &lt;a href=&quot;http://commons.erau.edu/cgi/viewcontent.cgi?article=1043&amp;amp;context=ijaaa&quot; rel=&quot;nofollow noreferrer&quot;&gt;research paper&lt;/a&gt; on the topic that suggests (in their conclusion) a pre spin situation would see &lt;strong&gt;1.07%&lt;/strong&gt; of the wear of a static situation. They go on to state that that they used a simple linear approximation and only accounted for forces in one direction but it would seem that it is beneficial for the tire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note&lt;a href=&quot;http://www.lufthansa-technik.com/landing-gear-overhaul&quot; rel=&quot;nofollow noreferrer&quot;&gt; this article&lt;/a&gt; even suggests the tires can be remolded so even if the are replaced often it seems they are recycled a few times. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an A340 will complete roughly 6,000 take-offs and landings, calling for about 25 sets of replacement tires, each 1.30 m high and weighing about 200 kg. The tires can be remolded several times before they are finally scrapped.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general, it's the job of the pilot to reduce the forces on the landing gear when landing. One of the best descriptions I have ever heard of landing is that the goal is not to land but to &quot;transition&quot;. In other words what you really want to do is transition the load from the wings to the landing gear as smooth as possible, this will reduce the load on the gear. In some cases (short runway heavy plane) your landing may see more force on the gear. I have never flown a 737, but I can tell you that I can put a Piper Warrior down on a 7000-foot strip with out ever feeling that you have touched the ground. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-07-07T21:27:50.240" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16665" PostTypeId="2" ParentId="8200" CreationDate="2015-07-07T15:08:13.593" Score="3" Body="&lt;p&gt;To give an idea of the states that are possible along with the indications (and generally the complexity of the system) here are some tables from a 767-300.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sH4HD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/G49fe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/bsdET.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-07-07T15:08:13.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16666" PostTypeId="2" ParentId="16659" CreationDate="2015-07-07T15:23:20.363" Score="9" Body="&lt;p&gt;From my research to date it seems that most general aviation and commercial fixed wing pilots are instead trained rigorously in crash avoidance rather than crash escape. Flight attendants and other cabin staff drill regularly in crash preparation and cabin evacuation in several situations (gear-down landing, belly landing, water landing, fires blocking escape doors X, Y and Z, etc) but in an emergency, the job of the people behind the yokes is to first make sure the plane gets back on the ground in as close to one piece as possible; nobody's walking away from a nose-down dive into a mountain.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-07T20:50:14.460" LastActivityDate="2015-07-07T20:50:14.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16667" PostTypeId="1" CreationDate="2015-07-06T21:12:25.363" Score="8" ViewCount="4446" Body="&lt;p&gt;The question is basically up there in the title; I need a default value for an app that won't do anything. A friend suggested XXX, but I'm sure there must be one reserved specifically for that purpose? ;-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a code that's used in the travel industry to denote &quot;enter city code here&quot; without actually being mapped to a metropolitan area/city/airport? I'm guessing it might be one beginning with Y... :)&lt;/p&gt;&#xA;" OwnerUserId="9245" OwnerDisplayName="Christian" LastActivityDate="2015-07-07T18:30:53.010" Title="Is there an IATA airport code that is unassigned and that can be used for &quot;any airport&quot;?" Tags="&lt;iata&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16668" PostTypeId="2" ParentId="8118" CreationDate="2015-07-07T15:57:15.923" Score="6" Body="&lt;p&gt;A spin is an aerodynamic, stable maneuver where one wing stalls and the other continues flying. To practice this maneuver once, turn into the dead engine of a twin engine airplane, the spin will be textbook perfect and you'll be back on the ground very quickly.&lt;/p&gt;&#xA;" OwnerUserId="9255" LastActivityDate="2015-07-07T15:57:15.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16669" PostTypeId="1" CreationDate="2015-07-07T16:11:07.027" Score="45" ViewCount="8048" Body="&lt;p&gt;The situation that led me to ask the question is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a student pilot with only about 10 hours of flight time. I passed the aptitude and personality tests prepared by &lt;a href=&quot;https://en.wikipedia.org/wiki/German_Aerospace_Center&quot; rel=&quot;nofollow&quot;&gt;German Aerospace Center&lt;/a&gt; (German: Deutsches Zentrum für Luft- und Raumfahrt).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instructor keeps on telling me since the very first couple of flights that I lack some talent and it's not really possible for me to become an airline pilot. (He has never flown as airliner, only military aircraft but he is obviously a good pilot with long teaching experience.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what is the possibility that he is right? How much and what type of talent is required?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Please note that I haven't caused any major safety problems, and other students claim that they made pretty much the same mistakes I do.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit : Since some people misunderstood the situation, I'll clear some issues:&lt;br/&gt;&#xA;1-) I'm on some scholarship program of an airlines company. Money isn't an issue.&lt;br/&gt;&#xA;2-) I'm generally considered to be pretty smart. &lt;br/&gt;&#xA;3-) There's no reason that I could be discriminated by the instructor.&lt;br/&gt;&lt;/p&gt;&#xA;" OwnerUserId="9254" LastEditorUserId="27883" LastEditDate="2019-12-25T01:33:58.633" LastActivityDate="2019-12-25T05:57:14.197" Title="How important is it to have talent to become airline pilot?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;airline-pilot&gt;&lt;student-pilot&gt;" AnswerCount="9" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16670" PostTypeId="2" ParentId="16667" CreationDate="2015-07-07T16:29:30.303" Score="11" Body="&lt;p&gt;Good question, no good answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the ICAO system, the identifier ZZZZ is reserved by that agency to designate on flight plans that the airport does not have an ICAO code assigned (not all airports do; for instance Qualicum Beach Airport in British Columbia is TCCAA registered and has TC and IATA codes but no ICAO code). There is no specific combination of alphanumeric characters reserved to mean &quot;airport not specified&quot;; if the flight plan does not specify an airport at a particular stop, the ICAO code field will be blank (which is valid in many circumstances in general aviation; float planes can set down on any relatively calm body of water, while bush pilots routinely fly out to a dot on the map in the literal middle of nowhere to deliver supplies or people to an established but temporary campsite).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XXXX is an unassigned but unreserved ICAO code that a few websites seem to be using for testing and demo purposes; FlightStats has a page for this code but the data is sparse and nonsensical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The IATA system labels practically all registered airports (primarily ones of interest to commercial flight, but all FAA-registered airports have a three-character code that have, with few exceptions, been adopted verbatim by IATA). The IATA has no specially reserved code for &quot;not specified&quot; or any other special case. The code ZZZ is currently unassigned, and is used informally by bush pilots to indicate an &quot;unregistered&quot; landing area similar to the ICAO system (though as IATA labels more airstrips especially in North America, this code is used more specifically for unimproved landing areas, which are common in backcountry areas of the Plains States, Northwest and Alaska). But again, that still indicates an entry was made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are writing a computer system for flight planning and you want a string value to indicate that the user has not specified an IATA identifier, the safest are null, the empty string, or three spaces. &quot;000&quot; is probably also safe, as IATA does not and likely will never use three zeroes for any valid identifier, and OOO is also not assigned. The code &quot;ANY&quot; is reserved for Anthony Municipal in Kansas, but the code &quot;NON&quot; is not currently assigned (though with no guarantee it will remain so). XXX, YYY and ZZZ are also unassigned but other repetitive letters are.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-07T18:30:53.010" LastActivityDate="2015-07-07T18:30:53.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16671" PostTypeId="2" ParentId="16669" CreationDate="2015-07-07T16:35:34.947" Score="36" Body="&lt;p&gt;You are asking the wrong question. Ask yourself this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Do I really want to become a pilot?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the answer is yes, then you can become a pilot. You only require hard work, and a lot of money (but we are not talking about this).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having talent is subjective. Sometimes you try to learn something new and you get into that relatively quickly. Sometimes you don't. It doesn't just depend on talent, but on several factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you feel that you are not making any different mistakes than other student pilots, then change your instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several discussions about changing flight instructors. You can benefit from these ones:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/9869/65&quot;&gt;What to look for in a flight instructor?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/16086/65&quot;&gt;Is there a downside to trying multiple flight instructors?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-07T16:40:41.543" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16672" PostTypeId="2" ParentId="16669" CreationDate="2015-07-07T16:59:15.043" Score="12" Body="&lt;p&gt;Like anything, a combination of talent and effort is usually required to become proficient and/or master a complex skill. The less talent you have, the more work you need to get to the same level as someone with more innate talent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your instructor is probably adopting the mindset that the commercial airlines get to pick the best of the best, so they will choose new recruits that show a very high aptitude for flight in general and commercial flight training specifically. The same applies to military flight schools like the one your instructor would have gone through; there's usually a hundred applications for every opening, so the recruiters are told to weed out anyone who's not absolutely perfect for the job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, let's draw a parallel. If you were to judge a student driver's lifetime aptitude for driving a motor vehicle from the first 10 hours of time you spent in the passenger's seat with them, and that judgment carried any weight for a career doing it, there would be no professional drivers in the United States. Forget it. Insurance companies in the U.S. don't even back off the &quot;teen driver&quot; insurance rate until you're 25; if you got your license at 16 that's 9 &lt;em&gt;years&lt;/em&gt; of being considered &quot;high risk&quot; just because of your experience level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to aircraft, you can't even get your commercial pilot's license in the U.S. until you've logged at least 250 hours yoke time (as a PPL holder with at least 50 hours logged already and flying two hours a week for fun, it will take you up to four years to log that much time), and you can't even show your face on a commercial airliner as First Officer until you've logged 1,500 total flight hours, then you have to log another thousand hours minimum as First Officer to fly an airliner as Captain. And those are the absolute minimums, assuming you don't log any flight time that doesn't also directly contribute to another requirement of your commercial license such as cross-country, instrument approaches etc; a PPL can log a thousand hours and not meet the other requirements for a CPL, and most pilots double the minimum logged hours while meeting these other requirements. So, talent or not, if you haven't killed yourself or gotten your license pulled after almost &lt;em&gt;three thousand hours&lt;/em&gt; at the controls of an airplane, you know what you're doing and you've likely seen it all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to you and your instructor, I concur that it's probably not a good fit; your instructor is inspecting too much too soon (ten hours is really not even enough to accrue the necessary training for a solo endorsement), and I'd look around for another instructor with a little more patience for you to have some &quot;aha&quot; moments about flying.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-20T20:24:22.787" LastActivityDate="2015-07-20T20:24:22.787" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16673" PostTypeId="2" ParentId="16669" CreationDate="2015-07-07T17:00:41.810" Score="4" Body="&lt;p&gt;I assume your flying instructor does not work for the airline, and is not responsible for their hiring processes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that is true, then I wouldn't worry about it. You're not applying to be a military guy like him and you won't need his particular set of skills - we hope. :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally - much more experienced pilots have said you shouldn't have to rely on your superior flying skills.  What you really need is superior judgement, to avoid needing such skills...  I guess they know what they're talking about.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-07-07T17:00:41.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16674" PostTypeId="2" ParentId="16669" CreationDate="2015-07-07T17:06:13.057" Score="16" Body="&lt;p&gt;A bit of talent surely helps, but most important is the ability to learn and show progress. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A friend of mine had to do six simulator tests before he was admitted to the flight academy of his choice. Each one was a little bit more complicated than the previous one. After five tests he had perfectly demonstrated to lack any talent and they were about to fail him. They told him that he could do the final test if he insisted but that it would probably make little difference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He flew the final session flawlessly which demonstrated that he was a very good performer under high pressure. So they let him pass. Unfortunately a few months later he didn't pass a medical test due to unforeseen conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So talent isn't really needed, however it surely helps. As Farhan says, with hard work and lot's of money and good health you can become an airline pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is whether you really want to spend that money and effort on a job that provides little security in today's market? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is a bit off topic but you should do yourself a favour and look into the disputes between Lufthansa and their pilots, how Ryanair hires its crew, into the way Middle East airlines employ their pilots, what pay-to-fly schemes are, etc. Becoming an airline pilot today does not mean you will get the same working conditions as those who became airline pilots 40 years ago. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="65" LastEditDate="2015-07-07T17:22:22.060" LastActivityDate="2015-07-07T17:22:22.060" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16675" PostTypeId="2" ParentId="16624" CreationDate="2015-07-07T17:44:42.273" Score="15" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Placement on aircraft that fly above birds.&lt;/strong&gt; This is the #1 reason we don't hear about airliner bird strikes every day on the news; cruise altitude for airliners is around 30,000 feet, while only two species of bird have ever been recorded flying at that height, one in Central Africa, the other around the Himalayas, neither of these being common travel lanes for airliners. The critical time for most bird strikes is below the cloud ceiling and/or transition altitude, above which the air becomes thinner and birds have to work harder to stay aloft. Thus most birds fly below transition, while airliners spend as much of their flight time as feasible above it as the thinner air reduces drag and lowers fuel consumption (the &quot;strata&quot; of thicker air at the transition point, in addition to the simple reduction of SPL on the square of distance, also helps insulate people on the ground from jet noise).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Strong intake fan fins.&lt;/strong&gt; The first set of turbine fins that you see looking into a nacelle are the ones in the direct line of fire. They're also the largest fins, but in their favor there are higher acceptable tolerances for those fins versus the ones in the compressor stages. So, they're built strong to hopefully survive ingesting your average goose. &lt;a href=&quot;https://www.youtube.com/watch?v=r1f0Tk-tD6k&quot; rel=&quot;noreferrer&quot;&gt;Here's a YouTube of the A380 engine's bird strike test&lt;/a&gt;; the engine continues to operate even though the blade that was struck is misaligned on the turbine hub for a few rotations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Garbage disposer effect.&lt;/strong&gt; At ascent throttle levels, an airliner's engines are rotating between 10,000 and 15,000 RPM. Even travelling at cruising speeds of 500-550 knots, the rotation speed of the turbine will chop most organic matter into mincemeat in a fraction of a second. In fact, bird strike tests show the bird carcasses literally exploding from the force of impact with the rotating blades. These smaller pieces cause fewer problems passing through the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;High bypass.&lt;/strong&gt; About 80% of the air volume entering most underwing airliner engine nacelles passes around the turbine chamber instead of through it, increasing thrust while reducing fuel consumption. Fuselage-mounted engines on older aircraft had lower bypass ratios (one of the reasons those designs are being phased out of modern fleets). A bird entering the engine has a similar chance to pass right on through without encountering the combustion chamber.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Reinforced nacelle housing.&lt;/strong&gt; In the event a bird strike does dislodge something in the engine, the nacelle housing is engineered specifically to contain the shrapnel, minimizing the chance of damage to fuel and control lines in the wings and of course to the fuselage. (&lt;a href=&quot;https://www.youtube.com/watch?v=5-8_Gnbp2JA&quot; rel=&quot;noreferrer&quot;&gt;Here's a YouTube of a &quot;blade-out test&quot; for the A380's Rolls-Royce engines&lt;/a&gt;) The pilots will be alerted the engine has failed, and will cut off the fuel supply, engage fire suppression and run on the remaining engine(s).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Overspecification of required engine thrust.&lt;/strong&gt; One of the major tests an airliner design must pass before being FAA certified is an &quot;engine cutout at decision&quot; test. An aircraft is loaded to MTOW, taxis to the runway, the engines are spun up, the aircraft rolls out, then at the &quot;decision speed&quot; above which the pilot must commit to a takeoff, an engine is idled. The aircraft must still be able to get off the runway and attain a minimum climb rate. That test, for most modern two-engine jets, shows that the plane is perfectly capable of flying on one engine (if such a thing happened at takeoff in real life the jet would circle and land again but it would not have to risk an aborted takeoff above decision speed).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, these engines are built tough and tested tough, as is the rest of the aircraft (manufacturers build several planes' worth of components and subsystems for the express purpose of torture testing, and that's if they get it all right the first time). In addition to bird strikes, engines are tested for water ingestion, hail strikes, sand ingestion, smoke ingestion (a British Airways 747 lost all four engines after flying through the upper ejecta cloud of an erupting volcano; they got two restarted and landed safely, but future engine tests got even more stringent to avoid a repeat performance), and a host of other things that just aren't good for jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most famous bird strike incident in recent memory, Sully Sullenberger's emergency water landing in the Hudson River, was caused by hitting not one or two, but an entire &lt;em&gt;flock&lt;/em&gt; of birds, and not sparrows or pigeons, but Canada geese, which can weigh up to &lt;em&gt;20 pounds each&lt;/em&gt;. This incident is still a good example of how well engineered these engines are; both engines would have been at full revs as the plane was climbing out of LaGuardia, yet AFAIK the turbines, though deformed, didn't even part company with the hub, saving the control surfaces and lines for the ditch attempt, resulting in no fatalities and only one hospitalization.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-07T20:48:55.193" LastActivityDate="2015-07-07T20:48:55.193" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16677" PostTypeId="2" ParentId="16660" CreationDate="2015-07-07T18:45:33.370" Score="7" Body="&lt;p&gt;Flight training devices (FTD) are the non-moving, no-visuals cockpit replicas you seem to be reference as &quot;computer simulators&quot;.  These provide a real cockpit layout (real avionics, switches, buttons, etc) that are used as procedure trainers and to learn cockpit flows.  The main purpose of these is so you are aren't wasting time in the expensive full flight simulator and can get right to work once you get in there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once FTD training is finished, you move into the full flight simulator (FFS, typically a level-D sim per FAA certification) which are simulators with exterior visuals and a 6-axis hydraulic motion platform.  These are the devices used for the actual flight training in airline training.  You are expected in your first sim session to already know your way around the cockpit and not be too distracted by where all the buttons you need are so you can focus on the flight training.  Being at that comfort level for the first sim session is the purpose of spending time in the FTD to start.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-07-07T18:45:33.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16678" PostTypeId="2" ParentId="16661" CreationDate="2015-07-07T20:39:37.550" Score="2" Body="&lt;p&gt;The second part of the question is simpler. Aircraft are designed to handle all operational loads (=limit loads) as defined in the FAR or other regulations. Plus they have reserve strength requirements for larger loads (1.5 times or 1.25 times the limit loads). This latter loads are the ultimate loads, which the aircraft are usually required to stay-together for about 3 seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing wheel spin-up forces is desired, but it is not a winner of the trade-off against the complexity that arises from adding additional systems to spin the wheels up, before touchdown. It takes tremendous efforts to add new functions to existing, proven systems (landing gears in this case), and to prove that they will not fail under normal and foreseen failure conditions. If they will fail, then the structure will neglect the existence of such systems and the benefits of reducing loads would be gone.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-07-07T20:39:37.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16680" PostTypeId="2" ParentId="16540" CreationDate="2015-07-07T22:39:11.320" Score="2" Body="&lt;p&gt;When flying a tailwheel airplane or a tandem (two seats, front and rear) with a passenger in the front seat, you can't see much of the runway at all either landing or taking off. I use my peripheral vision to keep the plane centered between the edges of the runway and on track. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-07T22:39:11.320" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16681" PostTypeId="2" ParentId="16595" CreationDate="2015-07-07T22:55:49.283" Score="9" Body="&lt;p&gt;It is extremely rare for an R-zone to be able to be activated by NOTAM with less than four hours' notice. Most R-zones in the U.S. are on a regular schedule printed on sectionals, with a few activated by NOTAM by the using agency with at least four hours' notice, and sometimes several days' notice is required by law for a few zones created along well-traveled Victor routes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's more common is an R-area that is activated, but &quot;cold&quot;; the hazardous or politically-important activity for which the R-zone was created and activated is not happening right now, and is not expected to begin happening in the time it will take you to traverse it. So, the using agency that controls the space while active lets you in and tells whomever is performing the activity requiring activation of the zone to hang loose until you're clear. While you're in the space, it should not be allowed to go hot; if the nature of the activity, or the communications between whomever's doing the activity requiring the R-zone and the using agency controller, is such that the using agency can't guarantee the zone stays cold, you won't be allowed to enter it in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more common situation is a sudden &quot;temporary flight restriction&quot;. These can be enacted by the FAA and similar agencies at a moment's notice almost anywhere they have jurisdiction, typically in response to an emergency situation. The airspace above a forest fire, for instance, can be declared off-limits within minutes of the fire being reported, as both a hazard to flight in several ways (hot, highly-turbulent, low-oxygen, low-visibility air for thousands of feet above a major burn) and to allow firefighting aircraft to do their job. Airspace within nominal distance of an area of law enforcement activity can be cleared in a similar way, officially in the interest of pilot safety in case of weapons discharge, but just as often the real reason is to get news choppers away from the scene to minimize the chances of someone being shot or otherwise spectacularly killed on live TV.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an unplanned TFR is activated while you're in the airspace affected, you may not know about it until you land unless you're in contact with ATC or are intercepted by another aircraft and contacted on GUARD. The normal procedure would be to exit the airspace quickly and safely; this can be facilitated by ATC, who can vector non-participating aircraft to the nearest border of the TFR zone while maintaining separation.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T20:23:12.733" LastActivityDate="2015-07-23T20:23:12.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16682" PostTypeId="2" ParentId="16669" CreationDate="2015-07-07T22:57:35.753" Score="3" Body="&lt;p&gt;Everybody has his own learning path. A good instructor adapts to the way each student &quot;works&quot;. Even if not, you'll just need more time before you learn how to learn with him. I believe, anyone can be taught to become a pilot, eventually. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, not everyone will make a &lt;strong&gt;good&lt;/strong&gt; pilot. Please keep in mind, that after you've made your license you'll have to &lt;strong&gt;compete&lt;/strong&gt; for the seat in the cockpit. If you are competing against more talented people you are in a weak position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be a hard decision, but you must take it if you don't want your dreams crash disastrously after a few years of hard work (and quite a bunch of money, too). The best way, I believe, is first get your PPL, then ask few friends/instructors to honestly rate your flying skills. Continue towards the ATPL only if they rate you higher than 60%. Otherwise, my honest advice is that you &lt;strong&gt;stop&lt;/strong&gt; there and keep your PPL. After all, it's an amazing hobby! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wish you to make through your training soon. Success! &lt;/p&gt;&#xA;" OwnerUserId="9264" LastActivityDate="2015-07-07T22:57:35.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16683" PostTypeId="2" ParentId="16660" CreationDate="2015-07-07T23:01:48.333" Score="6" Body="&lt;p&gt;When I went through USAF pilot training...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Useful? Absolutely invaluable. Many of our instructors had experience before &quot;real&quot; simulators were used in training. All of them commented on how obviously better we were on our very first actual flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We had &quot;cockpit familiarization&quot; trainers. This looked like a cockpit, sat still on the floor, had all the switches but all they did was switch. They did nothing. We practiced &quot;switchology&quot;, checklists, and so forth. Beyond required time and tasks in this thing we could spend free time playing around with these. Not unlike checking out a book from the library.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above are very useful because it kept the &quot;real&quot; simulators available for actual flight training.  We had quite a few hours in this simulator before we got in a real airplane. And simulator training continued throughout the year in flight school.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But this does not give them the physical feel of controlling the airplane&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes it does. But as we got more expert in the aircraft, flying every day, sometimes twice a day, we could tell the difference. But the simulator feel was quite good and in no way did it hinder acquiring the touch for precision, when in formation for example.&lt;/p&gt;&#xA;" OwnerUserId="1798" LastActivityDate="2015-07-07T23:01:48.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16684" PostTypeId="1" AcceptedAnswerId="16749" CreationDate="2015-07-08T01:33:58.583" Score="15" ViewCount="1623" Body="&lt;p&gt;What are the differences between pre-transistor and transistor era jet engines? Towards the end of the second world war, most of the air powers had started development on jet engines. From what I understand, all of this predated any practical application of transistors. The transistor era obviously gave way to integrated circuits and microprocessors. On any piston engine I can usually spot the evolution of components because I'm well versed in the operation of piston engines. For jet engines it is less obvious to me, there are for example differences between turbofan and turbojet engines. I superficially understand the difference between them but I've never even operated one, much less been hands on with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the significant changes from pre-transistor to transistor-era jet engines? I've never seen vacuum tubes used on jet engines so it doesn't seem like it is just a matter of &quot;they replaced the tubes&quot;.&lt;/p&gt;&#xA;" OwnerUserId="9266" LastActivityDate="2015-07-09T21:13:37.377" Title="What are the differences between pre-transistor and transistor era jet engines?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16685" PostTypeId="2" ParentId="3794" CreationDate="2015-07-08T03:06:49.267" Score="-4" Body="&lt;p&gt;If your radio was broken during a flight, you could use a light or come up with a sign of help that a helicopter or other airplanes can see so that they can contact the radio people and rescue them to safety. &lt;/p&gt;&#xA;" OwnerUserId="9267" LastEditorUserId="774" LastEditDate="2015-07-08T03:59:02.903" LastActivityDate="2015-07-08T03:59:02.903" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16686" PostTypeId="2" ParentId="16660" CreationDate="2015-07-08T03:48:49.763" Score="7" Body="&lt;p&gt;As someone who works on commercial flight simulators I hope I can help answer your questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a typical training environment you find the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Computer Based Training&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Custom designed applications are provided by various manufacturers and they are designed to represent/simulator the entire aircraft, or they can focus on a specific system like the Flight Management System. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples include&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cae.com/civil-aviation/simulation-products/cae-simfinity/cae-simfinity-two-dimensional-2d-trainers/&quot;&gt;CAE Simfinity&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aerosim.com/productstechnology/systemsknowledge.aspx&quot;&gt;Aerosim&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These tools are valuable because they can run on most any computers, and even tablets now, thus allowing the student to learn at their own pace without tying up an actual training device. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Training Devices&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are physical mock ups of the aircraft cockpit in question, there are various levels that these can be certified to that (mostly) relate to the hardware configuration. These are typically used for initial training only. These are fixed based and usually do not include any out the window visuals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Full Flight Simulators&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A full flight simulator provides a complete representation of the simulated aircraft in question. It consists of a fully accurate flight deck, a visual system, a control loading system and a motion system. There are 4 levels of certification a full flight simulator can receive (A, B, C and D) with D being the highest one currently. A level D simulator consists of a 6 degrees of freedom motion system as well as a wrap around collimated visuals. Level D simulators must provide additional special effects and cues to the pilot and there are more quality tests that are required to be run to demonstrate the simulator matches the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question, airlines most definitely do make use of full flight simulators and they are incredibly useful. The average level D simulator might cost $15 million dollars but it is a small fraction of the cost required to train on the real aircraft (factoring in fuel and maintenance etc.), stats I've read show that FFS training can be as much as 1/40th the cost of using the real aircraft. In addition to the cost savings, they allow crews to train for situations that would be too dangerous or impossible to simulate using a real aircraft (for example a sudden engine seizure at V1, among many others).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage of a level D simulator is that it is certified to allow zero flight time training, where the first flight a pilot flies is a revenue flight. Full flight simulators are used in both initial and recurrent pilot training.&lt;/p&gt;&#xA;" OwnerUserId="9247" LastActivityDate="2015-07-08T03:48:49.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16687" PostTypeId="1" CreationDate="2015-07-08T04:13:40.363" Score="5" ViewCount="1479" Body="&lt;p&gt;What are the requirements for a foreigner (personally I'm from Cyprus) to join the Royal Australian Air Force to become a fighter pilot?&lt;/p&gt;&#xA;" OwnerUserId="8268" LastEditorUserId="1696" LastEditDate="2018-04-18T17:23:14.780" LastActivityDate="2018-04-18T17:23:14.780" Title="What are the requirements for foreigners to join the RAAF as a fighter pilot?" Tags="&lt;military&gt;&lt;pilots&gt;&lt;fighter&gt;&lt;jet&gt;&lt;australia&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16688" PostTypeId="1" AcceptedAnswerId="16693" CreationDate="2015-07-08T05:32:18.687" Score="7" ViewCount="739" Body="&lt;p&gt;When new engines are designed for aircraft (military or civilian) they undergo high altitude testing (especially the military ones).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is high altitude testing of engines? How is that important?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="3201" LastEditDate="2015-07-08T21:26:37.443" LastActivityDate="2015-07-08T21:26:37.443" Title="What is high altitude testing?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;aircraft-maintenance&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16689" PostTypeId="1" AcceptedAnswerId="16746" CreationDate="2015-07-08T05:35:14.647" Score="20" ViewCount="9939" Body="&lt;p&gt;Wikipedia article tells that &lt;a href=&quot;https://en.wikipedia.org/wiki/Supercruise&quot;&gt;supercruise&lt;/a&gt; is a condition when an aircraft can achieve velocities above Mach one without using the highly inefficient afterburners. But still, there are not a lot of engines which can achieve this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the specific requirement for an engine to achieve supercruise? Why can't most of the engines reach supercruise without reheats enabled?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="3201" LastEditDate="2015-07-08T21:19:50.120" LastActivityDate="2017-04-30T21:28:20.343" Title="How is supercruise achieved?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;engine&gt;&lt;supersonic&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16690" PostTypeId="1" AcceptedAnswerId="16699" CreationDate="2015-07-08T06:03:34.423" Score="27" ViewCount="4279" Body="&lt;p&gt;(By passenger airline in this question I mean scheduled carriers, with at minimum a few aircraft with 50+ seats.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am aware of 3 main classes of airlines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hub-and-spoke (most major airlines)&lt;/li&gt;&#xA;&lt;li&gt;Low-cost carriers (Southwest, Ryanair)&lt;/li&gt;&#xA;&lt;li&gt;Regional (contractors that support more &quot;spokes&quot; for the majors)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there more? If so, where and how are they used? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note: I accepted the answer that shows a clear example, but there are many other excellent answers below!&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-08-16T21:53:39.920" LastActivityDate="2015-08-23T20:24:23.710" Title="Are there any &quot;alternative&quot; passenger airline business models?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16691" PostTypeId="2" ParentId="16689" CreationDate="2015-07-08T06:20:46.533" Score="16" Body="&lt;p&gt;Almost any jet engine can be used for super cruise. Certain characteristics help, however:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/13522/can-a-convergent-nozzle-be-used-for-a-supersonic-jet-engine&quot;&gt;Convergent-divergent nozzle&lt;/a&gt; for supersonic exit velocities&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;Efficient intake with high pressure recovery&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Good thrust/weight ratio&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The aircraft needs to have sufficient thrust and low drag, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule&quot;&gt;area-ruling&lt;/a&gt; and a low flight mass help.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supercruise was invented as a marketing term for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-22&lt;/a&gt;. Note that a number of &lt;a href=&quot;https://aviation.stackexchange.com/questions/14509/in-what-way-are-the-concordes-engines-considered-efficient&quot;&gt;earlier designs could also cruise supersonically without afterburner&lt;/a&gt;. The stealth design of the F-22 requires the internal storage of weapons, which makes achieving super cruise easier. External stores full of weapons and external tanks would make super cruise practically impossible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-08T06:20:46.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16692" PostTypeId="1" AcceptedAnswerId="16694" CreationDate="2015-07-08T06:24:03.743" Score="10" ViewCount="3770" Body="&lt;p&gt;Often, airlines are unable to sell all the seats of a flight and some seats go unsold. &lt;strong&gt;So, with what occupancy ratio is it usually profitable for an airline to operate?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Recently, a Turkish Airlines A330, flying from Bangkok to Istanbul (12,000 KM) made an emergency landing after a bomb hoax. The interesting thing was that it was carrying only 142 passengers, against its marked capacity of 250 passengers (occupancy ratio of about 0.6). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what are the factors which would influence this choice – like probably, it would be cheaper to operate a B787 with 0.6 occupancy ratio compared to a B747.&#xA;What are some other factors which influence this?  &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="22550" LastEditDate="2019-01-06T08:12:54.003" LastActivityDate="2019-01-06T16:29:52.827" Title="At what minimum occupancy ratio can airlines operate profitably?" Tags="&lt;commercial-aviation&gt;&lt;cost&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="16693" PostTypeId="2" ParentId="16688" CreationDate="2015-07-08T06:26:02.457" Score="7" Body="&lt;p&gt;High altitude means low air density. Ignition is &lt;a href=&quot;https://aviation.stackexchange.com/questions/10002/why-is-the-combustor-volume-of-a-jet-engine-decided-by-altitude/10014#10014&quot;&gt;harder to achieve with lower density&lt;/a&gt;, and the size of the combustor determines up to which altitude and throttle setting an engine will stay lit. Testing that it really works at those low densities before flying is a really good idea.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-08T06:26:02.457" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16694" PostTypeId="2" ParentId="16692" CreationDate="2015-07-08T06:30:23.113" Score="12" Body="&lt;p&gt;They can operate with 0 passengers, but will most likely not generate any revenue (unless cargo is carried to generate additional revenue). Revenue and profit on a passenger flight (assuming no paid cargo) will be based upon how many tickets were sold at which price, so the number of passengers required for any given flight to break even will be variable and cannot be answered in a general way.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-07-08T07:43:49.353" LastActivityDate="2015-07-08T07:43:49.353" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16695" PostTypeId="2" ParentId="16684" CreationDate="2015-07-08T06:35:21.723" Score="11" Body="&lt;p&gt;The vibration levels on jets preclude the use of vacuum tubes. They may work if everything is fine and all rotating parts are well balanced, but once you have a defect and an out-of-balance condition, the electronics would fail quickly, just when you need their help the most. Especially the afterburner adds a lot of vibration when it works as designed already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Earlier jet engines used hydraulics for adjusting things like compressor vane angles (litte stationary &quot;wings&quot; positioned between the rotating discs of the compressor, which help to convert rotational flow energy into compression) and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use&quot;&gt;nozzle size&lt;/a&gt;. Like on piston engines, the amount of adjustment was much lower back then, and all adjustments were done mechanically. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-08T08:10:54.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16696" PostTypeId="2" ParentId="16690" CreationDate="2015-07-08T11:33:58.577" Score="19" Body="&lt;p&gt;&lt;strong&gt;4. Business class airline&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airline which operate aircraft only have Business class for medium/long haul route.&#xA;Example: &lt;a href=&quot;https://www.google.com.hk/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CB0QFjAA&amp;amp;url=https%3A%2F%2Fwww.lacompagnie.com%2F&amp;amp;ei=X0WdVc_AD4WcugTTm4u4DA&amp;amp;usg=AFQjCNFvigjlDAXmkr_xMxJ1Mdq78hw6qQ&quot; rel=&quot;nofollow&quot;&gt;La Compagnie&lt;/a&gt; (Paris Gaulle / London Luton - Newark)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airline also operated All-Business class service in some of their route.&#xA;Exapmle: &lt;a href=&quot;http://www.britishairways.com/en-gb/information/travel-classes/business/club-world-london-city&quot; rel=&quot;nofollow&quot;&gt;BA Club World London City&lt;/a&gt; (London City - JFK), and cancelled &lt;a href=&quot;https://en.wikipedia.org/wiki/Singapore_Airlines_Flight_21&quot; rel=&quot;nofollow&quot;&gt;Singapore SQ21/22&lt;/a&gt; (Newark - Singapore).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check &lt;a href=&quot;https://en.wikipedia.org/wiki/Business_class_airline&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; for further detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Wikipedia claimed that Lufthansa also have All-business class flight but i cannot find such a seat arrangement in &lt;a href=&quot;http://www.seatguru.com/airlines/Lufthansa/information.php&quot; rel=&quot;nofollow&quot;&gt;seatguru&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: SAS have all business-class services between Stavanger and Houston (SK951/952) with b737 operated by &lt;a href=&quot;http://privatair.com/current-services.html#breadcrumb&quot; rel=&quot;nofollow&quot;&gt;Privatair&lt;/a&gt;. Qatar also provides all such services between Doha and Heathrow (QR 15/16) with A319 but the &lt;a href=&quot;http://www.businesstraveller.com/news/101821/qatar-airways-to-end-a319-all-business-lhr-service&quot; rel=&quot;nofollow&quot;&gt;service will be terminated soon&lt;/a&gt;. (Thanks for @Calchas )&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-08-17T20:57:49.877" LastActivityDate="2015-08-17T20:57:49.877" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16697" PostTypeId="2" ParentId="14405" CreationDate="2015-07-08T11:48:19.763" Score="3" Body="&lt;p&gt;I am not aware of specific regulations regarding ATC training simulators. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC simulator training is usually done on an exact copy of the real system (same software &amp;amp; hardware). The radar data is provided by flight simulators which are operated by pseudo pilots (also called blip drivers). These are in 'radio contact' with the trainee. One pseudo pilot usually operates multiple aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft simulation usually consists of a very basic three degree of freedom point mass model, an aircraft performance model (e.g. BADA) and a rudimentary autopilot. The pseudo pilot translates commands from the Air Traffic Controller into new autopilot settings. The simulator then calculates the flight path resulting from the settings and provides radar data to ATC system. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-07-08T11:54:01.840" LastActivityDate="2015-07-08T11:54:01.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16699" PostTypeId="2" ParentId="16690" CreationDate="2015-07-08T13:51:41.297" Score="27" Body="&lt;p&gt;There's also the &quot;Snowbird&quot; model, like &lt;a href=&quot;https://www.suncountry.com/page/1/destinations.jsp&quot; rel=&quot;noreferrer&quot;&gt;Sun Country&lt;/a&gt; and &lt;a href=&quot;https://www.allegiantair.com/route-map&quot; rel=&quot;noreferrer&quot;&gt;Allegiant Air&lt;/a&gt;, which primarily fly vacationers and snowbirds between sunbelt (San Diego to Florida) and the Carribean, and the Northern snowbelt states (Maine through Washington State, and Canadian border cities). They are low-cost carriers, with few or no code shares, no connections, no free amenities, and prices that decline as the date gets closer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is Sun Country's route map.  Note that nearly all their flights are between Minneapolis (or Dallas) and vacation destinations.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/UReiG.png&quot; alt=&quot;Sun Country route map&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a part of Allegiant's route map, showing cities with flights to Phoenix/Mesa, AZ.  They have more routes than are shown here, but all their routes have one end in one of the &quot;sun belt&quot; cities marked in orange.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/0Ee2f.png&quot; alt=&quot;Allegiant partial route map&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="2546" LastEditDate="2015-07-08T17:15:42.637" LastActivityDate="2015-07-08T17:15:42.637" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16700" PostTypeId="1" AcceptedAnswerId="16703" CreationDate="2015-07-08T14:20:41.440" Score="35" ViewCount="41090" Body="&lt;p&gt;I once heard my pilot friend say that it's really dangerous to fly near any Cumulonimbus cloud formations... Something about that it could drag the plane into it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cumulonimbus :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/O2s15.jpg&quot; alt=&quot;Image of Cumulonimbus cloud formation&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why is it so dangerous?&lt;/li&gt;&#xA;&lt;li&gt;How is it created?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="9276" LastEditDate="2015-07-08T18:15:21.387" LastActivityDate="2015-07-09T20:42:41.960" Title="Why is the Cumulonimbus cloud formation so dangerous?" Tags="&lt;weather&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16701" PostTypeId="2" ParentId="16690" CreationDate="2015-07-08T14:31:18.973" Score="17" Body="&lt;p&gt;Even within the different categories in the question, there are multiple business models, which can be quite different from each other.&lt;/p&gt;&#xA;&lt;h2&gt;&amp;quot;Low-Cost Carrier&amp;quot; Category&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Within low-cost carriers, you have Southwest on one end of the spectrum, which is kind of debatable as to whether it should even be considered a low-cost carrier these days. They charge almost no extra fees for anything and offer frequent flights to almost all major cities, but have base fares that are usually quite comparable to those of the major airlines on the same routes. JetBlue also follows a similar model to Southwest.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the other end of the spectrum, you have airlines like &lt;a href=&quot;https://en.wikipedia.org/wiki/Allegiant_Air&quot; rel=&quot;noreferrer&quot;&gt;Allegiant&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/WOW_air&quot; rel=&quot;noreferrer&quot;&gt;Wow Air&lt;/a&gt; which charge extra fees for just about everything except cabin pressurization, mostly just fly into small-market airports, have very limited route options, offer only a few flights per week on a given route, and often don't offer connections. These are quite different business models.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the middle of these extremes, you have the business models of airlines like Spirit and Frontier, which have fees and schedules in between those of the airlines on the ends of the spectrum.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h2&gt;Regional Category&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Within the regional category, one business model that exists in the U.S. is that of the airlines that exist primarily to provide &lt;a href=&quot;https://en.wikipedia.org/wiki/Essential_Air_Service&quot; rel=&quot;noreferrer&quot;&gt;Essential Air Service (EAS)&lt;/a&gt;. EAS is a government-subsidized program designed to ensure that scheduled passenger service is available to remote areas that are not near cities large enough to support significant scheduled passenger service profitably on their own. Airlines operating these routes still usually ferry passengers to larger airports where they can connect to other airlines like other regional carriers, but often operate much smaller aircraft (e.g. 13-20-seat aircraft vs. the 50 or 70 seat aircraft common on normal regional carriers.) Airlines exist almost solely to run these types of routes include &lt;a href=&quot;https://en.wikipedia.org/wiki/Great_Lakes_Airlines&quot; rel=&quot;noreferrer&quot;&gt;Great Lakes Airlines&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/SeaPort_Airlines&quot; rel=&quot;noreferrer&quot;&gt;SeaPort Airlines&lt;/a&gt; (which ironically has its largest hub in Memphis, which isn't a seaport and doesn't offer service to any seaports.) For examples of the kinds of routes these airlines operate, here's the route map for SeaPort:&lt;br /&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/8Y1CR.jpg&quot; alt=&quot;SeaPort Airlines' Route Map (as of July 2015)&quot; /&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Traditional regional carriers within the U.S. typically operate 50-70-seat regional jets. These carriers are usually contracted to 'do business as' the regional wing of one of the major airlines (e.g. Delta Connection, American Eagle, or United Express.) They usually fly from hubs of the airlines they contract with to small-market airports, but not as small as those served by the EAS program. Additionally, the regional carriers are used to provide service between an airline's smaller hubs and medium-market or even large-market airports. For example, in the case of Delta, while a city may have mainline Delta 757 service to Atlanta, it may have only regional airline service to their smaller hubs like MSP, CVG, and SLC.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-08T16:14:14.127" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16702" PostTypeId="2" ParentId="16700" CreationDate="2015-07-08T14:32:58.053" Score="2" Body="&lt;p&gt;There are two primary reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Cumulonimbus clouds are formed by rising water vapor droplets which cause powerful upward air currents; obviously this creates very unstable and turbulent air which could be detrimental for an aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Torrential rain, frost and lightning can be dangerous for a numbers of reasons - but mostly for icing on aerodynamic surfaces and pitot tubes becoming blocked.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9240" LastActivityDate="2015-07-08T14:32:58.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16703" PostTypeId="2" ParentId="16700" CreationDate="2015-07-08T14:33:28.857" Score="44" Body="&lt;p&gt;A cumulonimbus cloud (CB) is dangerous because of the processes occurring in them.  At a minimum you will have an updraft and a downdraft containing rain.  The particular CB you posted in your picture is typical of severe convection.  The anvil is spreading out along the tropopause and there is significant overshooting tops over the anvil.  This indicates the updraft in this cloud is very strong and there is a lot of energy in this storm.  A storm like this likely has hail near the updraft, very strong winds both up and down and severe turbulence within the interface between and around the strong up/down drafts.  There can also be very active in-cloud lightning as well as cloud-to-ground discharges.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Threats near the storm are turbulence, lightning, large hail and significant downdrafts (e.g. microbursts).  Threats within the cloud are severe turbulence, very strong updrafts (some as high as 100 m/s or more) and downdrafts containing torrential rain, hail and lightning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To better illustrate the magnitude of vertical winds, here is a quick plot from a modeled storm I am working with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/sRKvJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this plot the reds are updraft and blues are downdraft with the scale on the right in meters/second.  The plot covers 20 km x 20 km area at a height of 5.4 km, which is close to 18,000 ft or 500 mb.  This corresponds to the main updraft in a supercell and you can find areas where less than 5 km cover a vertical wind gradient of 50 m/s.  If you were penetrating this at any decent airspeed you would be in for a very rough ride.&#xA; This storm only had 1800 J/kg CAPE and updrafts can be much faster than this. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;CB clouds are (typically) realized from a release of convective available potential energy (&lt;a href=&quot;https://en.wikipedia.org/wiki/Convective_available_potential_energy&quot; rel=&quot;noreferrer&quot;&gt;CAPE&lt;/a&gt;), which is simply a measure of how much warmer a parcel rising from the surface is than its surroundings as it rises.  In an environment that is favorable for convection (CAPE, vertical windshear) where there is ample moisture and a mechanism to force parcels to rise to their level of free convection you can end up with a CB cloud.  A CB is simply a cumulus cloud with rain falling out of it and whether this is a small rainshower or a severe rotating supercell is determined by the environment the storm occurs in.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-09T00:49:19.073" LastActivityDate="2015-07-09T00:49:19.073" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16704" PostTypeId="2" ParentId="16687" CreationDate="2015-07-08T14:59:31.050" Score="4" Body="&lt;p&gt;Only citizens of a country can apply in the government jobs (including armed forces) of that country. There can be some exceptions but I hardly doubt that a foreigner can be hired or trained for any position in military which has access to classified information. Being a fighter pilot even has more restrictions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Royal Australian Air Force &lt;a href=&quot;http://www.defencejobs.gov.au/airforce/jobs/Pilot/&quot; rel=&quot;nofollow&quot;&gt;does not hire any foreigner&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Can I apply if I am not an Australia Citizen?&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;To be eligible to join the Air Force, you must be an Australian&#xA;  Citizen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to Recruitment Centre of Australian Defence Force, &lt;a href=&quot;http://www.defencejobs.gov.au/recruitmentCentre/canIJoin/citizenship/&quot; rel=&quot;nofollow&quot;&gt;this page lists the proofs required for citizenship&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-07-08T17:47:11.387" LastActivityDate="2015-07-08T17:47:11.387" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16705" PostTypeId="2" ParentId="16669" CreationDate="2015-07-08T15:44:10.027" Score="2" Body="&lt;p&gt;Talent is important, so is luck, and so is having decent instruction but in my opinion, most important is having the right attitude. That means when things are not going as you expect, taking positive action to change them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your instructor says you don't have talent. Fair enough, maybe they are right, maybe not. Coming here to ask if it is important isn't really addressing the issue though since you still don't know what it is your instructor is talking about and that means you still do not know what action you need to take to change your instructors opinion. You respect your instructor, which is a good thing, but do not grant them authority they do not have or make assumptions without evidence &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;he is obviously a good pilot...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;then why is he teaching beginners and why don't they know what he is talking about?&lt;/p&gt;&#xA;" OwnerUserId="2233" LastEditorUserId="65" LastEditDate="2015-07-09T13:58:45.043" LastActivityDate="2015-07-09T13:58:45.043" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16706" PostTypeId="1" AcceptedAnswerId="16715" CreationDate="2015-07-08T15:45:05.427" Score="10" ViewCount="1045" Body="&lt;p&gt;At the &lt;a href=&quot;https://www.youtube.com/watch?v=vo0ZN2_O29M&amp;amp;t=470&quot;&gt;end of airshow display&lt;/a&gt; (just before landing), the dassault rafale seems to slow down very quickly as it reach the top a final loop. It seems as if the pilot apply full airbrakes, but it seems there is no special flight control surface deployed to perform this function. How is this feature performed? Is it a special configuration of the split elevons? A combination of elevons and canard?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="15311" LastEditDate="2020-04-17T17:16:26.860" LastActivityDate="2020-04-17T17:16:26.860" Title="How is airbrake function performed on the Dassault Rafale?" Tags="&lt;flight-controls&gt;&lt;fighter&gt;&lt;airbrakes&gt;&lt;rafale&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16707" PostTypeId="1" AcceptedAnswerId="16744" CreationDate="2015-07-08T16:08:23.243" Score="7" ViewCount="1191" Body="&lt;p&gt;I'm quite puzzled after seeing some videos of the Dassault Rafale. When pulling the stick, the canard plan should move as in &lt;a href=&quot;https://www.youtube.com/watch?v=UDsfZNBg14s&amp;amp;t=79&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; (low speed, high angle of attack, stick pulled backward on average). But, &lt;a href=&quot;https://www.youtube.com/watch?v=vo0ZN2_O29M&amp;amp;t=70&quot; rel=&quot;nofollow&quot;&gt;this a high load and high speed maneuver&lt;/a&gt;, the canard plan's position should be similar but it is not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is that possible? Does the canard plan act as a canard plan only at low speed, the elevon doing most of the job at high speed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm double puzzled as this canard behaviour &lt;a href=&quot;https://www.youtube.com/watch?v=0CEzWS15yCQ&amp;amp;t=287&quot; rel=&quot;nofollow&quot;&gt;seems to be the same for the SU-30&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1467" LastEditDate="2017-12-06T09:44:42.903" LastActivityDate="2017-12-06T09:44:42.903" Title="How does the canard plan of the Dassault Rafale work?" Tags="&lt;flight-controls&gt;&lt;fighter&gt;&lt;maneuver&gt;&lt;control-surfaces&gt;&lt;rafale&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16708" PostTypeId="2" ParentId="16669" CreationDate="2015-07-08T16:20:24.993" Score="-9" Body="&lt;p&gt;That is a polite way of saying you are not smart enough. You are not alone. For the majority of people who try to fly the same exact thing happens as happened to you. The instructor can tell in the first 5 minutes if a student can &quot;make it&quot;, meaning they have the intelligence and coordination to learn to fly a plane. If they are sub-par, then the first flight just becomes a &quot;ride&quot; and when the aircraft gets on the ground the instructor gently breaks the news to the student somehow. In your case he tells you, you &quot;lack talent&quot;. Each instructor has his own way of doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying an aircraft is HARD. Things happen simultaneously in 3 dimensions with 6 degrees of freedom. You have to be a certain intelligence level to do it, which is about 130-135 IQ. If a person is below this level, it is very dangerous for them to fly and they have a high probability of making an error that will kill them and possibly other people. There is no shame in not being a genius. Every person needs to know and respect their limitations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are you lucky you had a good instructor. There are unscrupulous instructors out there who will string a non-candidate along, taking their money even though they know the student can never be soloed. This is greedy and dangerous, because they keep taking dangerous students up in the air. It sounds like your instructor has been taking you up multiple times, however, and he really shouldn't be doing this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying is fun and a great dimension to life, but for most people, unfortunately, they need to do it from the passenger's seat. There are a lot of ways to enjoy flying without being a pilot. I encourage you to explore those other options.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Comment on some of the other answers:&lt;/strong&gt; Some of the other answerers, who are obviously not CFIs, have said things to the effect that &quot;anybody can fly if they want to hard enough.&quot; This is both a factually wrong idea and expresses a dangerous and delusional attitude. An aircraft is not like a car that just runs into a ditch when you screw up. An aircraft WILL kill anybody who is not fully competent and tries to fly, and I know of several such people who have killed themselves in that way. CFIs do not tell unqualified students not to fly because they are jerks. They tell them that to save their money and maybe their life. Listen to them.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-07-08T16:31:23.087" LastActivityDate="2015-07-08T16:31:23.087" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="16709" PostTypeId="1" AcceptedAnswerId="16710" CreationDate="2015-07-08T16:57:04.420" Score="33" ViewCount="4552" Body="&lt;p&gt;On the only jet engined aircraft I'm trained on, the Bell 206B (Allison 250 engine), I was taught to move the throttle slowly and smoothly, especially when opening.  I've also see this done with Rolls Royce testing RB211s and early Trents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've realised I don't actually know why this is.  Is it to prevent possible flame out with a sudden increase in fuel with no corresponding increase in air mass since the engine will spool up much more slowly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do modern engines need this handling?  &lt;a href=&quot;https://www.youtube.com/watch?v=lbqsMXJ8skk&quot;&gt;In this video at about 0:17&lt;/a&gt;, the pilot commences the roll by more or less slamming the throttle open. My guess is that like all other computer controlled controls, the FADEC interprets this as &quot;as much fuel as possible without flaming out&quot;.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="3825" LastEditDate="2015-08-13T03:44:46.043" LastActivityDate="2020-03-13T08:17:02.940" Title="Why should jet engine throttles be moved smoothly?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16710" PostTypeId="2" ParentId="16709" CreationDate="2015-07-08T17:07:03.993" Score="33" Body="&lt;p&gt;The issue is the possibility of a compressor stall.  The combustion will directly respond to changes in the thrust lever but it takes time for this to spool up the turbine that is connected to the compressor.  If the incoming air from the compressor is not of adequate pressure because it hasn't spooled up enough you risk a compressor surge.  In these engines you need to slowly increase thrust so that the turbine can spool up (and hence the compressor) so the airflow through the engine remains adequate for the engine power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern engines with FADEC systems should not have these issues as the FADEC can enforce rate limits for fuel flow increases or directly calculate the maximum safe fuel flow from observed engine parameters.  Modern engines might also have more sophisticated compressors with variable stators that can help mitigate compressor stalls/surges.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-07-08T17:07:03.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16711" PostTypeId="2" ParentId="16690" CreationDate="2015-07-08T17:13:21.380" Score="12" Body="&lt;p&gt;Yes. The three categories there are not really reflective of many aviation businesses around the globe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Formerly full service, not yet LCC&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In many parts of the world (especially Europe) you have older carriers desperate to reposition themselves as low cost carriers. They have inherited large cost bases and they are trying to shed them, often with limited success. They often adopt the tactics of a &quot;low cost&quot; airline such as charging for amenities and operating on point-to-point routes. But their cost base (per available seat mile) remains as high as even the legacy, global carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So they look like an LCC but actually they would not be considered an LCC by an investor. (Indeed many of them remain owned by sovereign funds.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the UK, Flybe (BE) might be a good example, although it is not in government ownership. BE charges low(ish) fares, it focuses on point-to-point routes, most of its routes are under 500 miles, it charges for snacks, it charges for luggage and there is no business class. However, until very recently it had a typical cost per available seat kilometre exceeding that of British Airways shorthaul!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;LCCs are Flybe's biggest competitors and their lower average unit cost across their networks allows them to under-price Flybe when they do compete on the same city pairs. Even without direct competition, LCCs have a downward impact on pricing in many markets as they compete for discretionary travel spend. This could become a major threat to Flybe, especially if the level of overlap with LCCs grows.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://centreforaviation.com/analysis/flybe-a-niche-occupied-by-few-other-airlines-but-still-with-a-unit-cost-disadvantage-200156&quot;&gt;http://centreforaviation.com/analysis/flybe-a-niche-occupied-by-few-other-airlines-but-still-with-a-unit-cost-disadvantage-200156&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip side BE offers feed to airlines such as KLM, Cathay Pacific and British Airways. It also wetleased aircraft to Finnair in a joint venture with them called Flybe Nordic (an affiliate member of oneworld). These are not activities typical of a low cost carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think I would also put CityJet (WX) in this category. It was recently demerged from the AF/KLM group. WX does have a &quot;base&quot; at London City Airport (LCY), but it really focuses on point-to-point rather than transfer traffic (LCY is too expensive to compete for transit traffic). Costs and fares are high, but it's a good airline.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This weak unit revenue trend, at an airport [London City] that is considered to be high yield, is troubling, especially given the capacity cuts. Although the relative trend of RASK [revenue per available seat-kilometre] versus CASK [cost per available seat-kilometre] started to move in the right direction in 2013, it will be a considerable achievement to restore breakeven and then to convert that into sustained profitability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://centreforaviation.com/analysis/cityjets-new-owner-intro-aviation-to-acquire-new-fleet-rebrand-move-ho-to-dublin-peter-oncken-176467&quot;&gt;http://centreforaviation.com/analysis/cityjets-new-owner-intro-aviation-to-acquire-new-fleet-rebrand-move-ho-to-dublin-peter-oncken-176467&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;LCCs now offering full service amenities (&quot;hybrid&quot; carriers)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the original low cost carriers are close to saturating the &quot;low cost&quot; market in Europe and realize the only way to continue growing is to offer fares and service levels that are acceptable to business passengers—or indeed, discerning leisure passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EasyJet (U2) has a new CEO who is making a strong push for business traffic by using central airports, better times, reliability, offering fast lane access, a loyalty programme called &quot;EasyJet plus&quot;, and so on. Revenues have grown strongly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://centreforaviation.com/analysis/easyjet--ryanair-squaring-up-to-each-other-as-head-to-head-competition-increases-208098&quot;&gt;http://centreforaviation.com/analysis/easyjet--ryanair-squaring-up-to-each-other-as-head-to-head-competition-increases-208098&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A direct competitor to Flybe on UK domestic routes, whom I use quite often, is a relatively new airline called Eastern Airways (T3). T3 goes the opposite route: luggage is free, all of its passengers get fast track at all airports, it provides a free lounge at its hub, there is free coffee/beer/wine/snacks on board. Yet it charges low fares (most of the time), offers no feed or interline connections, does point-to-point only, and it only operates a fleet of turboprops (and one SAAB).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(However most of their planes have fewer than fifty seats, so maybe this example isn't directly relevant.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“We’re offering a frequent business schedule with an all-inclusive on board service, both of which are equally important to business travellers.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.anna.aero/2014/01/22/eastern-airways-returns-onto-leeds-bradford-southampton-route/&quot;&gt;http://www.anna.aero/2014/01/22/eastern-airways-returns-onto-leeds-bradford-southampton-route/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;All premium long haul carriers&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other posters have mentioned the annoyingly named &lt;em&gt;La Compagnie&lt;/em&gt; (try asking &quot;Pardon, où est l'enregistrement pour la Compagnie?&quot; in CDG...) offering all-busines service on PAR-NYC and LON-NYC. There have been one or two of these airlines in the past but they always struggle without the benefit of a major airline to rescue their passengers when the plane goes technical. Odyssey Airlines wants to try the same thing on LCY-JFK, but presently no aircraft can do the route without a stop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://centreforaviation.com/analysis/all-business-class-north-atlantic-airlines-will-odyssey-airlines-epic-tale-end-in-triumph-171835&quot;&gt;http://centreforaviation.com/analysis/all-business-class-north-atlantic-airlines-will-odyssey-airlines-epic-tale-end-in-triumph-171835&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However all of these operations are relatively &quot;niche&quot; and are only operating with about 30-50 seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low cost long haul&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some think this will be the future. The obvious examples are Norwegian (DY) which operates a number of all economy services between Europe and USA and a few between Europe and the far east. I think they deserve to be in a separate group to low cost short haul. The challenges of operating a long haul service are quite different to low cost short haul; on many routes offering only economy and economy plus products is going to be difficult to sustain without sophisticated revenue management work to milk every cent out of those passengers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually, these operations will require feed from other low cost carriers, they'll require local &quot;hubs&quot; or interchange points, and that's when things will get interesting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AirAsia X is one example of an airline already going down that route. It has a strong relationship with the various AirAsia brands and offers full interlining between shorthaul and longhaul services. Indeed, the low cost terminal at KUL had to be redesigned to enable bag-collect and re-drop prior to customs/passport control to enable better flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would agree that many of the airlines I've cited here to rebut your three categories are a little bit exceptional, but I think AirAsia X and EasyJet are the airlines to watch because they are not constrained by starting in one category. The three &quot;niches&quot; you gave will not be hard dividing lines for long.&lt;/p&gt;&#xA;" OwnerUserId="8565" LastEditorUserId="8565" LastEditDate="2015-07-09T08:28:34.620" LastActivityDate="2015-07-09T08:28:34.620" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16713" PostTypeId="2" ParentId="16690" CreationDate="2015-07-08T17:19:50.553" Score="10" Body="&lt;p&gt;Yet another airline model is local carriers that do not primarily act as spokes, but only for their own niche markets. I believe the planned California Pacific Airlines intends to pursue this model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arguably, charter airlines can also be considered another airline business model. Rather than operating on a fixed schedule, these companies will fly on demand. I believe these types of airlines are often used by travel agencies in Europe to ferry vacationers to their destinations. For instance, Germany's Hapag-Lloyd/TUIfly, as well as Germany's former LTU, works this way at least for some of their business.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are similar small-scale charter operations flying to Southern California's Santa Catalina island, as well as into the Alaska wilderness (and likely also in many other places, such as Yellowstone, Montana)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another airline business model is specializing on sightseeing tours - flights that depart and land in the same place. LTU used to offer such flights to the North Pole. On a smaller scale, many similar companies exist in or near scenic locations, such as Alaska, Hawaii, the Grand Canyon, and probably also many international locations (Kenya's Serengeti, for instance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet another business model is the private jet shared ownership.&lt;/p&gt;&#xA;" OwnerUserId="7742" LastActivityDate="2015-07-08T17:19:50.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16714" PostTypeId="1" CreationDate="2015-07-08T21:45:25.100" Score="11" ViewCount="26313" Body="&lt;p&gt;Large runways usually have a marked touchdown zone, and a marked aiming point (with two giant bars in the US). How is that location chosen? It seems like it is frequently further down the runway than I would have thought maximized available runway length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How important is it for an airliner to land on that spot? Are there regulations about this?&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-07-09T19:03:41.030" Title="What determines the touchdown zone and aiming point markings on a runway?" Tags="&lt;runways&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16715" PostTypeId="2" ParentId="16706" CreationDate="2015-07-08T22:07:59.653" Score="8" Body="&lt;p&gt;The Dassault Rafale has no dedicated airbrakes. By having two means of pitch control, namely wing elevons and canards, in combination with relaxed stability and an advanced &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_control_system&quot; rel=&quot;noreferrer&quot;&gt;FCS&lt;/a&gt;, it can move both into extreme deflection angles without sacrificing pitch control. &lt;a href=&quot;https://defenseissues.wordpress.com/2013/08/24/dassault-rafale-analysis/&quot; rel=&quot;noreferrer&quot;&gt;This site&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When landing, both canards and trailling-edge control surfaces can be&#xA;  used for braking, and Rafale may be able to use canards for braking&#xA;  even while in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, having little load to carry helps. The display aircraft was most likely flying close to its minimum wing loading (which is just 276&amp;nbsp;kg/m²), and by cutting back thrust could employ its regular aerodynamic drag for braking.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-07-08T22:07:59.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16716" PostTypeId="2" ParentId="16692" CreationDate="2015-07-08T23:03:19.817" Score="5" Body="&lt;p&gt;Generally, it is a load factor of roughly 70%, but the answer depends on many factors. Also, many airlines operate a fleet of different types of aircraft so the answer is never easy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;100% load factor @ 100 seats × \$100/seat = \$10,000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;\$10,000 − operating costs (fixed and variable) = profit per flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One you add in aircraft type, ancillary revenues, and total amount of flights, and the routes/network, the answer gets very complicated.&lt;/p&gt;&#xA;" OwnerUserId="9279" LastEditorDisplayName="user5604" LastEditDate="2019-01-06T16:29:52.827" LastActivityDate="2019-01-06T16:29:52.827" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16718" PostTypeId="2" ParentId="16593" CreationDate="2015-07-09T00:06:18.867" Score="3" Body="&lt;p&gt;I'm likely reading the same sources than you read. The chance of the event you are searching for ever occurred seems slim. As you wrote, Austria worked hard to maintain its neutrality policy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Austrian_Air_Force&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, it seems clear Austria was not using guided missiles before 1993, but indeed other weapons can be used to shoot down an enemy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article seems to be exhaustive for significant elements related to flights over the country by foreign aircraft, and still doesn't mention any destruction between 1970 and 1993.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a major incident in 1991 with Yugoslav MiG-21, but no mention of a shot down. This incident and the similar ones the same year led to the adoption of guided Sidewinder missiles by the air force two years later.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;From 1970, Austria purchased a total of 40 Saab 105 lightweight&#xA;  multi-role aircraft with the intention to deploy them in trainer,&#xA;  reconnaissance, interception and ground attack roles. As it became&#xA;  clear in the 1980s that the sub-sonic aircraft were inadequate for air&#xA;  combat and airspace interdiction, Austria purchased 24 reconditioned J&#xA;  35 Draken fighter aircraft to supersede the Saab 105 as the Austrian&#xA;  Air Force's main interceptor in 1988. The Saab 105 remained in service&#xA;  as a trainer/surveillance aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Shortly after, the Draken saw their first major use in airspace interdiction starting 1991 during the Yugoslav Wars, when Yugoslav&#xA;  MiG-21 fighters crossed the Austrian border without permission. In one&#xA;  incident on 28 June a MiG-21 penetrated as far as Graz, causing&#xA;  widespread demands for action.&lt;/strong&gt; Following repeated border crossings&#xA;  by armed aircraft of the Yugoslav People's Army, changes were&#xA;  suggested to the standing orders for aircraft armament.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Since 1955, Austria's armed forces had been forbidden to operate any&#xA;  guided missile system, including Air-to-air missiles and&#xA;  surface-to-air missiles. In the post-Cold War environment, and with&#xA;  gun-armed aircraft a relic of a past age, the Austrian Parliament&#xA;  voted to amend this section of its state treaty and in January 1993&#xA;  modern AIM-9 Sidewinder missiles were ordered from Sweden to arm its&#xA;  fighter aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the other assumption that Switzerland provided military assistance, again no mention of such cooperation until recent year, with the EU treaties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems the overflights of Austria by non authorized aircrafts was quite intense --daily-- at the time of the Yugoslavia war.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may be right when saying that Austria could be reluctant to disclose a shooting. The fact that it would have happened before the widespread use of Internet is not something that could prevent the event to be recounted online today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not relevant downing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jan. 1992: Two &lt;a href=&quot;https://en.wikipedia.org/wiki/1992_European_Community_Monitor_Mission_helicopter_downing&quot; rel=&quot;nofollow&quot;&gt;EU helicopters downed by Yugoslav MiG-21&lt;/a&gt;, Austria radars detected the downing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Additional documentation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.bundesheer.at/english/forces/airforce.shtml&quot; rel=&quot;nofollow&quot;&gt;The Austrian Air Force - In the Past and Today&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.scramble.nl/orbats/austria/overview&quot; rel=&quot;nofollow&quot;&gt;Austrian Air Force&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.globalsecurity.org/military/world/europe/at-fliegerdivision.htm&quot; rel=&quot;nofollow&quot;&gt;Austrian Air Force&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.acig.info/CMS/index.php?option=com_content&amp;amp;task=view&amp;amp;id=104&amp;amp;Itemid=62&quot; rel=&quot;nofollow&quot;&gt;A well documented list of interceptions over Austria&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.airpower.at/news01/1105_intercepts/&quot; rel=&quot;nofollow&quot;&gt;Austrian Draken's on high alert&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-07-09T00:06:18.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16721" PostTypeId="1" CreationDate="2015-07-09T04:40:55.980" Score="4" ViewCount="426" Body="&lt;p&gt;I just came across this article where an an Asiana 747 'collided' with an Aeroflot IL62 at the adjacent gate. As per the reports, IL62 had to be scrapped. From, what I read, it was like the Asiana pilot had a brain freeze.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering, in this case who payed for the damages and what happened to the pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19981111-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;accident description from aviation-safety.net&lt;/a&gt; and here's a photo of the 747's wingtip embedded in the vertical stabilizer of the IL-62:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MkhiR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9285" LastEditorUserId="1467" LastEditDate="2015-07-09T06:39:54.073" LastActivityDate="2015-07-09T18:06:48.243" Title="Who pays for the damages in this Asiana-Aeroflot collision?" Tags="&lt;safety&gt;&lt;incidents&gt;&lt;liability&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16722" PostTypeId="1" AcceptedAnswerId="16725" CreationDate="2015-07-09T05:12:20.550" Score="42" ViewCount="6944" Body="&lt;p&gt;I am not a pilot, but have a question about radar detection of improvised lawn chair balloons that I thought might be on-topic here.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lrpDT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.bbc.com/news/world-us-canada-33414264&quot; rel=&quot;noreferrer&quot;&gt;BBC news article&lt;/a&gt; describes a marketing stunt gone awry involving a lawn chair, a large number of multicolored helium balloons, and the owner/operator/parachutist&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the article, he was charged with &quot;mischief causing danger to life&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar stunt by American truck driver &lt;a href=&quot;https://en.wikipedia.org/wiki/Larry_Walters&quot; rel=&quot;noreferrer&quot;&gt;Lawrence Richard Walters, nicknamed &quot;Lawnchair Larry&quot; or the &quot;Lawn Chair Pilot&quot;&lt;/a&gt;  also resulted in fines and legal action.  In that case, the government dropped the fine for &quot;operating a civil aircraft for which there is not currently in effect an airworthiness certificate&quot; because it was not applicable to that type of aircraft. The article also mentions some other attempts to fly lawn chair balloons, including a fatality from crashing at sea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is whether such an improvised manned balloon would be visible on typical airport radar or the independent radar/collision-avoidance systems operated on board large modern passenger aircraft, and thus avoidable.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://www.dtic.mil/get-tr-doc/pdf?AD=ADA029262&quot; rel=&quot;noreferrer&quot;&gt;1970s military research paper on radar&lt;/a&gt; supporting the need for secondary transponders in detecting light aircraft also mentions detecting doppler from propellers (p.4) in addition to the primary radar reflection, and I would expect the cross section of a lawn chair to perhaps be within an order of magnitude of that of a propeller.   A 2m x 0.5m x 0.5m sparsely filled aluminum chair frame is also still larger than typical microwave radar wavelengths (1Ghz = 30cm wavelength, most radars are going to be above 1Ghz), so it should reflect the radar but of course is a fairly small object compared to large aircraft and therefore the detection range could be lower.&lt;/p&gt;&#xA;" OwnerUserId="9286" LastEditorUserId="9286" LastEditDate="2015-07-09T05:40:15.363" LastActivityDate="2015-07-10T20:51:31.223" Title="Would a homemade lawn chair balloon be visible on ATC and collision avoidance radar?" Tags="&lt;safety&gt;&lt;radar&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16724" PostTypeId="2" ParentId="16722" CreationDate="2015-07-09T07:28:56.580" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;My question is whether such an improvised manned balloon would be visible on typical airport radar or the independent radar/collision-avoidance systems operated on board large modern passenger aircraft, and thus avoidable. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Would it show up as a primary radar target? Yes, it could. Primary radar would however rather see the whole bunch of balloons rather than the chair, so it would create a primary target. Primary radar sometimes picks up flocks of birds, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it show up on TCAS or FLARM? No, as TCAS and FLARM are based on radio signals being broadcast and received between the devices, either transponder or other TCAS, or in the case of FLARM, other aircraft equipped with FLARM. Neither of these devices pick up airborne objects that do not emit signals.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-07-09T07:36:34.037" LastActivityDate="2015-07-09T07:36:34.037" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16725" PostTypeId="2" ParentId="16722" CreationDate="2015-07-09T08:38:00.640" Score="44" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Would a homemade lawn chair balloon be visible on ATC and collision avoidance radar?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It &lt;em&gt;might&lt;/em&gt; be visible to ATC, but, at best, only as one of several inconspicuous unidentified red dots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It wouldn't appear on aircraft collision avoidance displays (TCAS) and would not trigger any TCAS alerts.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Radar cross section&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Balloons, and clusters of balloons are mostly air (or similarly insubstantial gas). There is a thin layer of plastic but many plastic materials (e.g. mylar) are transparent to radar, or only weakly reflective.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is for this reason that aerostats and &lt;a href=&quot;https://www.balloonchallenge.org/tutorials&quot; rel=&quot;nofollow noreferrer&quot;&gt;high altitude balloons&lt;/a&gt; carry &lt;a href=&quot;http://sentintospace.com/products-page/flight-components/radar-reflector/#ad-image-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;radar-reflectors&lt;/a&gt; when they need to be detected by radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether the chair itself has a detectable radar cross section depends partly on what materials it is constructed from. I suspect most available lawn chairs are not constructed from solid sheets of metal fixed at right angles but, at best, from a relatively tiny amount of relatively small-gauge metal tubing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd be surprised if any improvised lawn-chair balloon had the same radar cross-section as a glider - and those are allegedly &lt;a href=&quot;http://www.dg-flugzeugbau.de/radar-reflector-e.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;hard to see&lt;/a&gt; on primary radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helium balloons are made from metallised mylar (because it keeps the helium in for longer). These may be much more reflective to radar. The Calgary aviator pictured was said to have used &quot;oversized party balloons&quot; - they don't look like the metallised balloons that are commonplace where I live.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A perfectly conducting metal sphere of 1.15m diameter has a radar cross section of 1 m²&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some other radar &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar_cross-section#Measurement&quot; rel=&quot;nofollow noreferrer&quot;&gt;cross section values&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Human: 1 m²&lt;br&gt;&#xA;  small combat aircraft: 2–3 m²&lt;br&gt;&#xA;  Cargo aircraft: up to 100 m²  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This suggests that military radar might display a return to an operator. A civilian primary radar might be less likely to display a return to an operator.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Primary radar&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;So far as I can tell, most civilian ATC and powered aircraft (TCAS etc) don't really make much use of primary radar to detect other airborne vehicles. They rely on transponder returns (i.e. secondary radar)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a large metal object like a Boeing 777 can disappear from the view of ATC and other aircraft when it turns off its transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Guardian newspaper &lt;a href=&quot;http://www.theguardian.com/world/2015/jan/29/russian-bombers-english-channel-ambassador-summoned&quot; rel=&quot;nofollow noreferrer&quot;&gt;reported&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Last month, the Swedish government complained that a Russian military aircraft had been flying near its airspace with its transponders turned off to avoid being spotted by civilian radar, and nearly collided with a passenger jet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'd be surprised if an improvised lawn-chair balloon was detectable where a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-95&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-95&lt;/a&gt; was not.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What ATC see&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This is from what is said to be a radar &lt;a href=&quot;https://www.youtube.com/watch?v=P0GI-1gja5Q&quot; rel=&quot;nofollow noreferrer&quot;&gt;recording of flight 77&lt;/a&gt; (at 4:18) probably at Dulles after controllers were aware of the prior 9/11 attacks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eEbuf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight 77 had turned off its transponder, it is one of the small red dots at the left. Here's a closer look at that&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/0pKyH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight 77 is the red dot about 20% in and up from bottom left. There are other red dots that come and go but this one tracks steadily from left to right. I'd guess an especially alert controller who is not very busy would notice this sort of dot.  Even if the radar display doesn't filter it out,  unannounced slow-moving lawn-chair balloons appearing from the suburbs might not always be noticed (though see James' comment to &lt;a href=&quot;https://aviation.stackexchange.com/a/16730/1289&quot;&gt;Peter's answer&lt;/a&gt; which suggests they often do notice and act on such targets). &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Transponders&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Radios and transponders designed for hot-air balloons are available (&lt;a href=&quot;http://www.lambert-aircraft.com/eng/avionics-special.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;example&lt;/a&gt;) and I've &lt;a href=&quot;http://www.4-flight.co.uk/transponder&quot; rel=&quot;nofollow noreferrer&quot;&gt;read&lt;/a&gt; that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Transponders are mandatory for flights in some types of airspace in many parts of Europe from March 2008 onwards. This includes balloons and other light / recreational aviation and aircraft. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I suspect that authorities will expect aviators in lighter-than air vehicles will take appropriate measures to be in communication with ATC/other aircraft and perhaps to be visible to secondary radar in airspace where they may come into conflict with other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Kevin Walsh&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Heres a news report from &lt;a href=&quot;https://news.google.com/newspapers?nid=1368&amp;amp;dat=19840719&amp;amp;id=fGscAAAAIBAJ&amp;amp;sjid=4U4EAAAAIBAJ&amp;amp;pg=7001,3617123&amp;amp;hl=en&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Milwaukee Sentinel - Jul 19, 1984&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OhzJl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Snopes &lt;a href=&quot;http://www.snopes.com/travel/airline/walters.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;reports&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;He had wrapped his tether lines in foil in the hope that they would show up on radar, and, sure enough, he was picked up on the screens of controllers at Boston's Logan airport&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you probably need to take specific measures to make yourself more likely to show up on primary radar. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When attaching balloons to your lawn chair, first scrutinize the intertubes for designs for large improvised radar reflectors you can dangle from your vehicle. Hope that nearby on-duty ATC controllers have their displays set to show primary radar returns and not just secondary radar returns.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-07-10T20:51:31.223" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16726" PostTypeId="2" ParentId="16709" CreationDate="2015-07-09T08:43:10.313" Score="33" Body="&lt;p&gt;Compressor stall is only one reason. Casey is right: Moving the throttle too quickly leads to an oversupply of fuel which in turn will add too much energy to the air in the combustor, heat it and let it expand more quickly than what the turbine will accept. This will increase the pressure in the combustor over that in the last stage of the compressor, and the heated air will escape the combustor in both directions. That is a fancy way of saying that the compressor stalls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the oversupply of fuel in the combustor will also overheat the engine components. Given that jet combustors run rather lean, there would be plenty of oxygen left to burn the extra fuel. Temperature would rise quickly before the air mass flow can help to cool the combustor. Both the combustor and the turbine would overheat, and in the worst case the engine would be destroyed. Modern engines use computer control to increase fuel supply only slowly. Before that, the pilot had to be careful not to move the thrust levers forward from idle too quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An added risk on multi-spool engines is compressor surge from a dynamic imbalance. The lower inertia of the high-pressure spool allows it to speed ahead of the low-pressure spool, and now the later stages of the compressor run too quickly and are starved of air, because the low-pressure part cannot pump enough air to keep the high-pressure compressor from stalling. Only careful application of thrust commands or computer control can limit the extra heat in the turbine such that the high-pressure compressor will stay within its surge limits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-03-13T08:17:02.940" LastActivityDate="2020-03-13T08:17:02.940" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="16727" PostTypeId="1" AcceptedAnswerId="16729" CreationDate="2015-07-09T08:48:33.847" Score="13" ViewCount="17798" Body="&lt;p&gt;I am studying the rate of climb of turbojets, I don't know how the thrust varies with altitude and in particular which are the differences between necessary thrust and effective thrust. &#xA;Hope being clear, I can't translate properly maybe so ask and edit !&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="5517" LastEditDate="2015-07-10T20:19:19.537" LastActivityDate="2018-05-22T12:04:36.527" Title="How does turbojet thrust change with altitude?" Tags="&lt;propulsion&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16728" PostTypeId="2" ParentId="16700" CreationDate="2015-07-09T09:28:17.730" Score="8" Body="&lt;p&gt;Since the mechanism of those upwinds has not been explained yet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cloud is generated by condensation of water vapour. That emits the energy once stored in the vapour as heat. The heated-up air rises through the cloud, sucking fresh air from below, that again condenses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That creates a strong upward air current, and depending on your plane, you might not be able to escape it. (There are regularly casualties of gliders and balloonists dying of hypoxia in high altitudes.) However, what goes up must come down, so around those clouds there are strong down-currents. The windshears between up- and downwind can be extreme.&lt;/p&gt;&#xA;" OwnerUserId="47549" LastEditorUserId="487" LastEditDate="2015-07-09T18:41:24.940" LastActivityDate="2015-07-09T18:41:24.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16729" PostTypeId="2" ParentId="16727" CreationDate="2015-07-09T09:56:01.450" Score="11" Body="&lt;p&gt;The thrust variation with altitude would be highly engine specific, but the general trend is nicely depicted in the image below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.grc.nasa.gov/www/k-12/Missions/Jim/thrust.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/Missions/Jim/Project1ans.htm&quot;&gt;Read&lt;/a&gt; this for further details.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-09T09:56:01.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16730" PostTypeId="2" ParentId="16722" CreationDate="2015-07-09T10:14:39.833" Score="24" Body="&lt;p&gt;Primary radars are sensitive enough to pick up even large birds. A lawnchair ballon would certainly register if the settings allow. To suppress the signals from birds and other non-aircraft objects, a minimum speed is required for primary radars to show a blip to the controller. Since the lawnchair is moving with the wind, it will be filtered out, unless the settings are changed, but then a lot of other signals will show up, too. To identify a lawnchair balloon will be almost impossible - the radar would need to track the ballon and distinguish it from birds due to the different, steady motion. I doubt that there is any such algorithm in regular use today.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-07-09T10:14:39.833" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16733" PostTypeId="1" AcceptedAnswerId="16740" CreationDate="2015-07-09T12:39:17.817" Score="4" ViewCount="467" Body="&lt;p&gt;If I make an airplane (lets say for research/recreational purposes), what kind of certifications would be required to fly it? Moreover, would I need special permissions to actually fly the airplane? What are laws regarding this to a situation specific to India?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="487" LastEditDate="2015-07-09T18:20:46.040" LastActivityDate="2016-04-29T17:01:32.360" Title="What kind of certifications are required for a plane manufactured for personal use?" Tags="&lt;general-aviation&gt;&lt;dgca-india-regulations&gt;&lt;airworthiness&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16735" PostTypeId="1" AcceptedAnswerId="16737" CreationDate="2015-07-09T13:45:22.593" Score="15" ViewCount="3213" Body="&lt;p&gt;I know some aircraft may land on iced surfaces. what are the difficulties associated and is this limited to specially designed aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DkJqg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some conditions necessary for the landing and the next takeoff.&#xA;Where are the main iced airfields currently active?&lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="258" LastEditDate="2015-07-10T16:50:43.943" LastActivityDate="2015-07-16T07:25:15.320" Title="What kind of aircraft may land on iced areas, like Antarctica?" Tags="&lt;landing&gt;" AnswerCount="4" CommentCount="22" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16736" PostTypeId="2" ParentId="9379" CreationDate="2015-07-09T14:02:22.220" Score="4" Body="&lt;p&gt;Military use UHF frequencies.  Each organization has a communication frequency for contact if you need to divert, have an emergency, or need guidance from higher authority.  When in formation, you have a tac frequency to talk to the other plane(s), but most communication of a non-tactical nature is done on traffic control frequencies.  ATC handles formations as a single flight.  Each member of the flight has a number Lead(1), 2, 3, etc.  Lead does all communications with ATC.  If you are directed to (for example, change altitude, the lead plane acknowledges with call sign and climbing to flight level 240 (if you are lower and going to 24,000 feet MSL.  The number two aircraft just responds &quot;2&quot; and the number 3 &quot;3&quot; and so on.  If you do not have a tac frequency and you need to have a conversation with another plane, you tell them to go to an informal channel like Winchester or popcorn.  Winchester is 303.0.  These informal channels were used extensively in Viet Nam to discuss what idiots the brass were.  Pilots had a code sheet that had a code for common expressions.&lt;/p&gt;&#xA;" OwnerUserId="9291" LastActivityDate="2015-07-09T14:02:22.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16737" PostTypeId="2" ParentId="16735" CreationDate="2015-07-09T14:09:33.160" Score="16" Body="&lt;p&gt;Yes it could, same way it would preform an emergency &lt;a href=&quot;http://www.city-data.com/forum/aviation/2023847-what-happens-if-jetliner-lands-sheet.html&quot;&gt;landing&lt;/a&gt; any where else. There are &lt;a href=&quot;https://en.wikipedia.org/wiki/Ice_Runway&quot;&gt;ice runways&lt;/a&gt; out there and its not all that uncommon to see &lt;a href=&quot;https://www.youtube.com/watch?v=b1LWE4-CDXk&quot;&gt;small GA planes&lt;/a&gt; landing on &lt;a href=&quot;http://www.wired.com/2015/03/landing-ice-runway-less-crazy-sounds/&quot;&gt;frozen lakes&lt;/a&gt; in the winter. There are considerations when it comes to breaking and what not but in the end of the day you have the ability to always land into the wind (since you are picking your touch down heading provided there are limited obstacles). Landing into the wind is also key as a result of some of the potentially high winds in the arctic and antarctic shelves. The largest issue is not knowing how thick the ice is. While I don't know an enormous amount about north or south pole geology the &lt;a href=&quot;https://en.wikipedia.org/wiki/Arctic_ice_pack&quot;&gt;ice thickness&lt;/a&gt; varies and in some places could not support an aircraft landing. For the most part the south pole ice is very thick &lt;a href=&quot;https://en.wikipedia.org/wiki/South_Pole&quot;&gt;(9000ft) by all estimates&lt;/a&gt;, but the outer edges and the ice that does not reside above the landmass could be thinner. Keep in mind that parts of the arctic/antarctic are in &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_night&quot;&gt;total dark&lt;/a&gt; for a part of the year so you may be looking at nigh procedures when landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough, &lt;a href=&quot;https://en.wikipedia.org/wiki/Transport_in_Antarctica&quot;&gt;Antarctica&lt;/a&gt; actually has &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airports_in_Antarctica&quot;&gt;20 airports&lt;/a&gt; so you may even be able to put down on a strip depending on where you are. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-10T13:12:47.017" LastActivityDate="2015-07-10T13:12:47.017" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="16740" PostTypeId="2" ParentId="16733" CreationDate="2015-07-09T16:10:36.783" Score="9" Body="&lt;p&gt;As Andy pointed out, this question is very broad (even if we're only talking about India). Your starting point should be &lt;a href=&quot;http://dgca.nic.in/&quot;&gt;the Directorate General of Civil Aviation (DGCA)&lt;/a&gt; because they can tell you definitively what would be involved in getting a &quot;homebuilt&quot; aircraft approved to fly under Indian law.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://dgca.nic.in/ftppub/D2F-F18.html&quot;&gt;Information about this is available on the DGCA website&lt;/a&gt; and is broadly similar to the FAA's &quot;Experimental: Amateur-Built&quot; certification requirements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft needs to be constructed in accordance with the DGCA's acceptable methods, techniques, and practices. Basically this means you can't use chewing gum as a structural fastener: The aircraft needs to be safe to fly.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft will be inspected by a DGCA representative prior to being allowed to fly.&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note that the DGCA inspection is mainly looking for &quot;obviously unsafe&quot; conditions - they don't do a teardown inspection so if you used chewing gum as a structural fastener and subsequently that area is covered up by a wing skin the inspector won't know, but &lt;em&gt;you&lt;/em&gt; will when the wing falls off on your test flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;You will need the DGCA to issue you a Certificate of Airworthiness before you can fly the aircraft around - that certificate is contingent on completing required test flights at the airport where the aircraft is based/built.&lt;/li&gt;&#xA;&lt;li&gt;You will need an appropriate pilot's license (and medical certificate if applicable) in order to fly the aircraft (this is also required to conduct  the Certificate of Airworthiness test flights mentioned previously).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-09T16:10:36.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16741" PostTypeId="2" ParentId="16700" CreationDate="2015-07-09T16:11:47.290" Score="5" Body="&lt;p&gt;In a sentence, cumulonimbus clouds, aka &quot;thunderheads&quot;, are more or less land hurricanes. They are formed when warm, humid air is quickly forced upward into higher altitudes where its water cools and condenses rapidly. This updraft can occur in many ways, as simple as high thermal heating or lateral winds being forced upward by terrain, to &quot;collisions&quot; of other weather events, like a strong warm front passing through an area of low pressure (which will pull in air from all directions, and the only plae the air then has to move is up) or a warm and cold front meeting with the cold air forcing the warm air higher. When this happens, a lot of moisture can suddenly no longer remain in vapor form, and condenses into rain, but the updrafts can keep the rain in the cloud for a while, letting more and more liquid form.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thunderheads pose several dangers at practically any altitude. At the surface, first is the torrential rain, which can reduce visibility to zero in the blink of an eye even for drivers on roads. Then you have the high straightline winds which can force vehicles with bigger cross-sections, like vans, box trucks and semis, off the road. Third is hail; the strong updrafts and downdrafts combined with the rapidly cooling air causes ice chunks to accumulate layers as they're tossed around by the air currents within the cloud, until they're finally too heavy to remain aloft and fall as hailstones. Here in North Texas, hail up to grape size is common with these storms, and the last really big storm we had produced reports of softball-size hail, which will destroy cars, punch holes in roofs and most definitely kill unsheltered people and animals. Last, and worst, is what happens when these strong updrafts and downdrafts are coordinated enough to form a vortex. Gyroscopic precession and the Coriolis effect will kick this vortex on its side, and you get the strongest weather event that can form over land; a tornado. Even the weakest of these are deadly to anyone who doesn't take shelter in a reinforced interior or underground space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft, you have all these hazards and many more. First is the severity of the updrafts and downdrafts; if the currents inside a thunderhead can keep a chunk of ice the size of a softball aloft, just think what it'll do to your little Piper Cherokee (or even a 747). Second is icing; as your plane is getting tossed around, the same near-freezing water condensation that forms hailstones finds the ultra-low-pressure environment over the top of your wings' leading edges simply irresistible. Third is debris; if there's an active tornado or even high straightline winds associated with this event, not only will you have ice flying around, but dirt/sand, rocks of varying sizes, tree branches, all the way up to Dorothy and Toto. Even planes with a military pedigree, like the P-3 Orions that are used to track hurricanes, can't survive this kind of onslaught.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't go anywhere near a thunderhead. Just don't. In fact, if you're a private pilot, don't even take off if there's a thunderhead anywhere near you, and if you're flying cross-country and see one, get on the horn with ATC immediately and request information on its course and speed and what you can do to avoid it. For pilots of small unpressurized craft the answer will usually be to put the storm front on your tail, open up the throttle and find the nearest airstrip that can take you.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-09T20:42:41.960" LastActivityDate="2015-07-09T20:42:41.960" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16742" PostTypeId="2" ParentId="16721" CreationDate="2015-07-09T18:06:48.243" Score="7" Body="&lt;p&gt;&lt;strong&gt;Short answer:&lt;/strong&gt;&lt;br&gt;&#xA;Someone's insurance company is writing a check.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Longer answer:&lt;/strong&gt;&lt;br&gt;&#xA;What usually happens in the insurance world is &lt;strong&gt;&lt;em&gt;both insurance companies write checks&lt;/em&gt;&lt;/strong&gt; to repair their respective clients' aircraft.  The insurance companies may then fight it out between themselves to determine who is responsible for what, &lt;em&gt;if it makes financial sense to do so&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cases where injuries or deaths result from an incident it almost always makes sense for the insurance companies to fight it out(those payouts can run in the millions of dollars).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cases like this where there's only equipment damage the cost of the repair will determine how aggressively Aeroflot's insurance carrier pursues getting their money back from Asiana's carrier.  If we're talking about extensive and expensive structural repairs into the millions of dollars Aeroflot's insurance carrier will be motivated to get someone else to pay the bill. Conversely if the insurance company can make their money back through Aeroflot's premiums and pursuing Asiana for negligence or something along those lines to try to get them to pay for the repair would ultimately cost more (money and time pursuing the case) than just absorbing the loss the insurance carrier will just absorb the loss.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-09T18:06:48.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16743" PostTypeId="2" ParentId="16714" CreationDate="2015-07-09T18:12:42.583" Score="8" Body="&lt;p&gt;There are actually several different indicators on the end of a runway. Here's a diagram of the most common ones during the day:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KwV3P.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... and at night:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wmla0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first touchdown indicator, as shown, is usually placed a set distance (here 500') from the threshold of the usable runway. Then, there are additional markers at 500' increments. Which one the pilot will aim for on approach depends on the plane he's flying, its weight, and instructions from the tower such as to land &quot;deep&quot; or &quot;shallow&quot; (light craft, and sometimes even commercial airliners, are often given these instructions to help manage air and ground traffic more efficiently at peak times).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can also see from the night shot, the glide slope lights (here using a system called PAPI which is a more precise indicator of slope than the older and more well-known &quot;white-over-red&quot; VASI) are positioned smack in the middle of the touchdown zone; again, with an approach path aiming directly for that point from the pilot's perspective, the plane will touch down on full-strength runway pavement even if he's in a 747-800.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, maintaining that glide slope all the way in is not the greatest idea, as a standard descent rate for an airliner on final approach is 400ft/min, which works out to more than 6 feet per second. Even the cushiest main gear struts are going to make that a pretty rough &quot;smack&quot; in the seats of the passengers and can cause very expensive damage to the airframe itself. To avoid that, pilots usually add a little throttle and/or pitch up a few more degrees in a maneuver called a &quot;flare&quot;, which reduces the rate of descent, ideally zeroing the plane's descent rate &lt;em&gt;just&lt;/em&gt; as the wheels touch. This means that during the last few seconds of approach, the glide slope decreases, moving the &quot;aim point&quot; further up the runway and causing the main gear to touch further down the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll find that if you look at the touchdown marks on older, well-used runway surfaces, touchdown of the main gear (remember that's anywhere from 50 to 150' behind the pilot's perspective and up to 25' below it) actually ends up centered pretty close to the ideal spot, due to the leveling off of the flare maneuver:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7bPqg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see in this image the average touchdown point (the widest and blackest part of the runway) is right at the PAPI lights to the left. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll also notice a few significant tire marks just a little too close to the threshold for comfort. Clearly landing a plane is not an exact science, and this is why the touchdown zone and aiming point is further down the runway than you might think; a sudden downdraft or a thinning of the air due to surface heat at just the wrong time in these crucial final seconds, and if the pilot was aiming for the threshold, his main gear will touch down short of it, possibly doing millions of dollars of damage to his plane, the runway and approach lighting as well as likely closing the runway.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-09T19:03:41.030" LastActivityDate="2015-07-09T19:03:41.030" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16744" PostTypeId="2" ParentId="16707" CreationDate="2015-07-09T19:01:50.053" Score="11" Body="&lt;p&gt;The answer is in two parts. First, at higher speeds, control surfaces have more air moving over them and so they don't have to angle as much to provide the same force necessary to move the jet as they do at slower speeds. In fact, a thin control surface like this canard will stall at lower angles of attack than a thicker profile would (the thinner profile reduces drag which is why it's used here), and a stalled surface can't do its job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, modern jets like the Rafale have fly-by-wire systems with flight limiters, to avoid the pilot overstressing the airframe at high speeds. The first video shows the Rafale in landing configuration, approaching a carrier at maybe 150kts. The second video shows high-G maneuvers at probably between 300 and 400kts. The forces at play on the canard are, in general, related to the square of the speed of the air moving past them, so if the system allowed the canards to present the same angle to a 300-knot flow as a 150-knot flow, all other things being equal the canard would be under 4 times the stress. At 450 knots that canard would be under 9 times the stress. Very quickly you would exceed the mechanical strength of that canard surface entirely, and then you wouldn't have a canard surface at all. So instead, the canards are moved at a shallower angle, with the difference in pitch rate, up to what the flight limiter will allow the entire aircraft to do, is made up using the elevons on the wings.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-09T19:01:50.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16746" PostTypeId="2" ParentId="16689" CreationDate="2015-07-09T19:59:16.110" Score="17" Body="&lt;p&gt;It's less about the engine and more about the combination of engine and plane. Theoretically, all that is needed is for the engine(s)' thrust without afterburners to be able to overcome the plane's inherent drag at a speed greater than Mach 1. Simple, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, to do that, you're up against some pretty heavy physics. First and simplest, given a drag coefficient for the aircraft in a &quot;clean&quot; configuration, the drag force increases on the square of velocity. So, to go twice as fast, you need four times the thrust with all other things being equal. Jet engines simply don't scale that way; you need a bigger engine to provide more max thrust, and then all things aren't equal anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, planes aren't built like cars, where in many cases there's enough room under the hood to drop in a bigger engine block and a turbocharger to double power for negligible additional weight. Fighter designs have to essentially wrap an aerodynamic skin as tightly as possible around the pilot, engine, avionics and fuel storage. For the longest time, engine efficiency was pretty static, therefore more thrust meant more engine. A bigger engine means a bigger plane, which means more drag, which offsets the thrust gains and thus the speed increase of the larger engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, there are some complex aerodynamic changes involved as a plane transitions the sound barrier. Airflow into the engines increases at higher speeds, which reduces the compression ratio of the engine; the intake turbines become less and less efficient as speed increases, and thus you get less and less benefit from the &quot;bypass&quot; airflow of the turbofan. Afterburners are more or less a simple way to continue to get more thrust after the intake turbines are no longer significantly compressing air, by taking that air, dumping a bunch of extra fuel in it and riding the prolonged explosion. This, however, uses ten to fifty times the aircraft's cruising fuel flow rate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 achieves supercruise in part by extending the efficient operating range of the engines with &quot;variable bypass&quot;. At lower airspeeds, engine bypass is increased to allow the turbofans to increase thrust with minimum fuel. At higher airspeeds when the turbofan effect decreases, compressor bypass is reduced to put more air into the combustion chamber (along with more fuel), which increases thrust beyond the normal compression limit more efficiently than simply burning the bypass airflow with an afterburner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, there is the simple requirement of supercruise in an aircraft's mission profile. Not many things in air combat occur at supersonic speed; you can't dogfight effectively at Mach 1 because your sustainable turn rate is measured in miles, you often can't drop gravity ordinance (bombs) because they won't fall away from the aircraft in a stable or predictable way, and in the case of the Raptor you have to open payload doors to deploy your weapons and that will increase your drag right there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supercruise has a singular purpose; to increase the speed of the aircraft's transit to and from the target zone without sacrificing range by dumping fuel into the afterburners at ten to fifty times &quot;military power&quot;. For an air superiority fighter (combination interceptor/dogfighter), that's very important, but the F-22 was the first U.S. fighter developed from the ground up to take advantage of the latest technological progress in aircraft design such that it could be achieved. The last time U.S. fighter designers got an opportunity to design a &quot;cost-is-no-object&quot; superfighter was almost 40 years ago with the F-15, and the two major fighter designs to enter U.S. service in the interim, the F-16 and F/A-18, were the result of a design competition specifically intended to create a lower-cost multirole fighter to serve as the bulk of the air fleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other supercruise-capable fighters designed by NATO allies reached production first; the English Electric Lightning interceptor is considered the first supercruise-capable production fighter (predating the coining of that term), and the Dassault Rafale is reported to be supercruise-capable in certain mission-ready configurations up to Mach 1.3, and beat the Raptor to market by about 2 years, though the Raptor has a substantally higher top speed under full military power (100% non-afterburning throttle).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-08T16:10:14.143" LastActivityDate="2015-10-08T16:10:14.143" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16747" PostTypeId="2" ParentId="16735" CreationDate="2015-07-09T20:00:19.477" Score="24" Body="&lt;p&gt;I've spent 6 summers in Antarctica (Mt. Erebus), travelling through McMurdo, where the busiest airstrips on the continent are. Most flights to McMurdo are on C-17s or C-130 Hercules. Some of the Hercules are LC-130 -- the L  indicates that they have skis. The skis enable them to land and take off on some including ungroomed or poorly groomed snow / ice surfaces. Sometimes they need JATO for takeoff, though, if the conditions aren't great.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;McMurdo has three runways which open and close operations during the year: Willy Field, Pegasus, and the Ice Runway. The Ice Runway is on sea ice and the other two are on the Ross Ice Shelf with Pegasus built on blue ice and Willy Field on snow. The Ice Runway breaks up each year during the height of the summer so it is carefully monitored. It bends downwards each time a C-17 lands. That deformation is measured and is one of the parameters that's used to decide when to stop using the Ice Runway each year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes, planes designed for non-military use are flown to McMurdo; the New Zealand Antarctic program often flies an Airbus A319 there. As far as I know, a well-groomed snow / ice runway can accommodate any plane in good weather. A Boeing 757 flight to McMurdo from Christchurch had a &lt;a href=&quot;http://www.taic.org.nz/LinkClick.aspx?fileticket=cEgLLLGBvM0%3D&amp;amp;tabid=36&amp;amp;mid=613&amp;amp;language=en-NZ&quot;&gt;scary incident recently&lt;/a&gt; where it was forced to land in low visibility because it didn't have enough fuel to &quot;boomerang&quot; back to New Zealand. The C-17s often boomerang due to bad weather. The Hercules, like the 757, don't carry enough fuel to boomerang, but they are better at landing in inclement conditions so it doesn't seem to be an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For flights within-continent, Twin Otters and Baslers are in common use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, there's no military presence with offensive capability. I don't really understand this (recently added) part of the question -- did you think they'd hit you with antiaircraft??? There's a bunch of air force guys who operate the flights, and a single US Marshall in McMurdo.&lt;/p&gt;&#xA;" OwnerUserId="7395" LastEditorUserId="7395" LastEditDate="2015-07-10T16:38:07.313" LastActivityDate="2015-07-10T16:38:07.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16748" PostTypeId="2" ParentId="16727" CreationDate="2015-07-09T20:58:48.710" Score="8" Body="&lt;p&gt;Thrust is produced by accelerating air. The exhaust air leaves the engine nozzle at a fairly fixed velocity, so the acceleration is mainly controlled by the difference between the exhaust and incoming airspeeds. The faster the aircraft speed, the less acceleration is being created on the intake air. Therefore thrust decreases with increasing airspeed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In level flight, an aircraft could not be accelerated above the engine exhaust gas speeds because then the incoming air would be faster than the exhaust air - resulting in a decelaration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most jets are operated as max speeds much less than their exhaust gas velocity - about half of V-exhaust I think.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since higher air-speeds are normally used at higher altitudes, thrust generally decreases with an aircraft's altitude. But increasing altitudes can erode thrust because the mass of air being consumed is also decreasing as the air gets increasingly more rarified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarize: At a constant airspeed (ignoring airspeed measurement nuances) thrust decreases as air density decreases with increasing altitude; at a constant altitude, thrust decreases with increasing airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that max thrust is found when stationary, just before take-off, since that's when incoming air is at its slowest. Also, at max thrust, (when airspeed is zero) there is no work being done and hence the power produced is zero right before takeoff.&lt;/p&gt;&#xA;" OwnerUserId="9300" LastEditorUserId="9300" LastEditDate="2015-07-11T01:26:28.807" LastActivityDate="2015-07-11T01:26:28.807" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16749" PostTypeId="2" ParentId="16684" CreationDate="2015-07-09T21:13:37.377" Score="10" Body="&lt;p&gt;The primary advance in the transistor era is the &lt;a href=&quot;https://en.wikipedia.org/wiki/FADEC&quot;&gt;FADEC&lt;/a&gt;. It's essentially a fly-by-wire throttle, incorporating rate limiters to key engine inputs such as fuel flow rate, and performing automated monitoring tasks to reduce flight crew workload. Prior to the FADEC system, sufficiently complex jet aircraft required a crew member, the flight engineer, whose primary task was monitoring and maintaining engine performance in flight. Additionally, jets without a FADEC require particular attention paid by the pilot(s) to the rate at which the throttle is adjusted; you can't just firewall it for a takeoff as that will cause a compressor stall.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-09T21:13:37.377" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16751" PostTypeId="2" ParentId="16735" CreationDate="2015-07-09T21:49:12.610" Score="7" Body="&lt;p&gt;Any plane with tires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the ice is plowed it scratches it up and that provides enough of a friction that landings are fairly normal, like landing on concrete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are ice runways in Greenland that are used regularly.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-09T21:49:12.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16752" PostTypeId="2" ParentId="126" CreationDate="2015-07-09T22:57:59.890" Score="3" Body="&lt;p&gt;The only way you can avoid doing the math is if someone else has already done it for you and you have the results of their work available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Towered airports, of course, will control the runway direction from the ground, and will handle any lighting systems. At non-towered but fairly busy airports there will be an accepted pattern in use, and when anyone notices the windsock is pointing the other way the pilots can coordinate to &quot;turn the airport around&quot; (I'm actually curious how that happens; for strips that always have a left-hand or right-hand pattern, the answer is simply to not turn to final and instead just circle to the other end, but for airstrips where, for instance, powered planes must always stay to one side of the airport to avoid a residential neighborhood, you can't circle that way, and must instead make a 180 away from the airport to reverse the pattern direction).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, your question infers that no radio chatter or other traffic is available to follow, and you have to determine it for yourself. You can still get some help in these cases. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Non-towered airports can still be lit; end lights and the LDI tetrahedron can be controlled from a simple automated weather station, and activated on request (to save energy) by pilots tuning to a station and clicking the mike.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the pattern is truly empty, you can maneuver around the strip, look for the windsock, and approach in the direction closest to its tail.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Use a compass card; any will do, you have several in your cockpit, or you could even have a literal &quot;compass card&quot;, a rose drawn on an index card on your clipboard or the inside cover of your notebook (whatever you're using for quick reference or shorthand notes on your flight). You know wind is from 225* and your options for runways are 13(0) or 31(0). A quick look at the dial will show you which runway choice is closer to the wind. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Just remember not to get confused by the numbers on the rose; to land on runway 31, you have to go around to the southeast end, even though 310* is marked on the northwest quadrant of the compass rose; runways are labelled according to the heading you'll be on while using them.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-13T04:11:05.760" LastActivityDate="2015-07-13T04:11:05.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16753" PostTypeId="1" AcceptedAnswerId="16755" CreationDate="2015-07-09T23:47:32.500" Score="5" ViewCount="245" Body="&lt;p&gt;Say you've properly tuned an ADF station in COMP mode so that the BRG needle on your RMI is pointing towards your station. Then you tune the same ADF frequency on your V/UHF radio. Does anything happen to your needle at this point? How about when you transmit on that frequency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Meant RMI&lt;/p&gt;&#xA;" OwnerDisplayName="user9302" LastEditorUserId="19" LastEditDate="2016-11-21T09:19:28.803" LastActivityDate="2016-11-21T09:19:28.803" Title="What are the effects of communicating on VHF/UHF on a RMI's ADF needle?" Tags="&lt;general-aviation&gt;&lt;radio-communications&gt;&lt;navigation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16754" PostTypeId="2" ParentId="16560" CreationDate="2015-07-10T00:47:40.943" Score="5" Body="&lt;p&gt;The post above comments on the F-16 originally having an immobile control stick, and that it had been modified in later versions to be more similar to a video game. As a professional video game developer who has actually been in a late-model F-16 simulator, I can tell you that it feels &lt;em&gt;nothing&lt;/em&gt; like a video game stick, and it feels a bit like pushing on an immobile metal rod that has been covered in a slightly spongy surface. It doesn't actually move in any direction, although the surface does have a bit of give, so it doesn't feel totally immobile. Despite the fact that I had never used one before, it was still relatively intuitive to use, and I didn't find it difficult, but it is dramatically different than a joystick. I haven't been in any other jet cockpits, so I don't know for sure, but I would assume they would all have to be dramatically stiffer than anything used in civilian life, if for no reason other than to avoid having it move during acrobatic maneuvers.&lt;/p&gt;&#xA;" OwnerUserId="2359" LastActivityDate="2015-07-10T00:47:40.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16755" PostTypeId="2" ParentId="16753" CreationDate="2015-07-10T00:56:38.377" Score="5" Body="&lt;p&gt;NDBs in the U.S. transmit between  90 kHz and 535 kHz, and VHF is between 108 and 137 MHz. Of the VHF frequencies, the nav/com is only capable of transmitting between 118 MHz and 137.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So aside from electromagnet interference, no VHF radio should transmit on a frequency that he ADF receives.  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-10T00:56:38.377" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16756" PostTypeId="2" ParentId="16649" CreationDate="2015-07-10T00:58:22.137" Score="2" Body="&lt;p&gt;At many of the airports I've flown in (as a helicopter pilot), they will also have rotorcraft fly in the opposite direction from fixed wing. Our descent profile and cruising speeds are different than aircraft, and given that we may do confusing things like slow down into a hover, its for the best. Generally they'll place us at a different altitude as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As other people mentioned, the fact that larger planes travel at different speeds is one reason they may place them in a different pattern, and I suspect it helps with wake turbulence as well. The planes can be spaced a bit closer together if large planes aren't comingled with the smaller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar setups will also happen in commonly used airways. For example, where I live in Chicago, and when flying westward through Midway/O-Hare airspace (they overlap), they'll generally have us fly along the highway. They tend to put the rotorcraft at a much lower altitude than the fixed wing, which I suspect is not only for the same reasons as above, but also because the altitude minimums for rotorcraft are lower than for fixed wing, and it gets more traffic out of the way.&lt;/p&gt;&#xA;" OwnerUserId="2359" LastActivityDate="2015-07-10T00:58:22.137" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16757" PostTypeId="2" ParentId="126" CreationDate="2015-07-10T01:02:03.613" Score="1" Body="&lt;p&gt;Rather than calculating off the wind direction, start with the runway headings. 13-9=4 and 13+9=22. If the wind is 040-220 use 13, otherwise use 31. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have an HSI so I set the bug to the wind heading and the CDI to the runway, then press vectors-to-final to get an extended centerline.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both easy peasy &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-10T01:02:03.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16758" PostTypeId="2" ParentId="16476" CreationDate="2015-07-10T06:14:39.523" Score="-2" Body="&lt;p&gt;Most of the aircrafts have covers (caps) so as to isolate the landing gear from the air around so as to prevent it from icing. Commercial airliners reach altitudes to the proximity of 35000 feet (and maybe more in some cases) and temperatures could drop 80 degrees below zero. In such cases, if the landing gear has caps and is isolated from the free stream, the heat retained in the landing gear bay from the hydraulics and the friction in the tires while takeoff does keep the landing gear warm and hence protect it from icing (&lt;a href=&quot;http://www.latimes.com/local/lanow/la-me-ln-maui-california-stowaway-20140421-story.html&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Heat from the plane’s hydraulic lines in the wheel well, as well as&#xA;  heat retained in the tires, could have helped the stowaway survive as&#xA;  the aircraft climbed to altitudes with sub-zero temperatures, the FAA&#xA;  reported.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now, for airplanes like the one shown above, there is a possibility of the landing gear getting iced. When this happens, it might cause a range of problems. Problems ranging from skidding while landing to jammed landing gear. Usually, before landing when an airplane descents, the rise in temperature is good enough to deice the landing gear, but if that does not happen then pilots need to tackle with the icing problem in flight itself. &lt;a href=&quot;http://www.skybrary.aero/index.php/Landing_Gear_Problems:_Guidance_for_Flight_Crews&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When surface temperatures are low enough for frozen deposits to be&#xA;  present, consider whether the mechanisms might have become frozen&#xA;  during flight as a result of prior extended taxiing through slush or&#xA;  wet snow. Flight above the freezing level for prolonged periods may&#xA;  result in the landing gear becoming frozen in the retracted position.&#xA;  This is less of a problem on most modern commercial transport&#xA;  aircraft, where the gear bays are largely enclosed by doors unless&#xA;  retraction/extension is in progress, but is a relatively common&#xA;  occurrence on aircraft such as the LOCKHEED AC-130 Spectre. If it is&#xA;  suspected that taxiing through slush or wet snow may have led to&#xA;  deposits adhering to the landing gear assemblies, then it may be&#xA;  advisable to cycle the gear after initial post take off retraction to&#xA;  try and shed any deposits.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-10T06:14:39.523" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16759" PostTypeId="2" ParentId="3766" CreationDate="2015-07-10T08:00:11.370" Score="12" Body="&lt;p&gt;Besides the location of the center of gravity, two things determine how an aircraft spins, and both are not well shaped for spinning in paper airplanes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wings (obviously): They should ideally be straight with an aspect ratio between 5 and 10. Swept wings will also spin, but straight wings make spinning and recovery easier.&lt;/li&gt;&#xA;&lt;li&gt;The forward fuselage. Here a rounded shape which is higher than wide is ideal and will promote flat spins. The two-dimensional shape of paper airplanes will not produce the vortices which drive the yaw rate in spins.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, for spinning it needs a stalled wing, some asymmetry and some time until the spin fully develops. To create a strong pitch-up moment, masses at the tip and the end of the fuselage are also needed. A pure paper airplane will have too much yaw damping and too little inertial pitch up to spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Size should be less of an issue because separated flow changes less with Reynolds Number, and spin tunnels regularly use scales of 1:20 or 1:30 with good results. But I wonder whether the low wing loading of a paper airplane will prevent spins - the models used in spin tunnels are carefully sized not only for geometric agreement, but also for their masses and mass distribution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe it will be better to show your students &lt;a href=&quot;https://www.youtube.com/watch?v=M7QkTBKtyw8&quot; rel=&quot;nofollow noreferrer&quot;&gt;videos from spin tunnel tests&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=-HDnYnmE8qU&quot; rel=&quot;nofollow noreferrer&quot;&gt;Spin tunnel footage of fighter aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=dCG5xdy4k10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Spin tunnel footage of GA aircraft&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=-AfYlqI2wKM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Description of a spin tunnel&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-03-13T16:25:37.163" LastActivityDate="2020-03-13T16:25:37.163" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16760" PostTypeId="1" AcceptedAnswerId="16762" CreationDate="2015-07-10T08:28:55.520" Score="8" ViewCount="725" Body="&lt;p&gt;Regarding the fuel system in an aircraft, I read that there are two valves: the intertank valve and the crossfeed valve. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are both motor driven butterfly type valve which function is to allow fuel from the left and right hoppers to combine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the differences between them? &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="65" LastEditDate="2015-07-10T13:40:09.720" LastActivityDate="2015-07-21T11:01:26.823" Title="What are the differences between intertank valve and crossfeed valve?" Tags="&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16761" PostTypeId="1" AcceptedAnswerId="16767" CreationDate="2015-07-10T12:37:32.627" Score="10" ViewCount="3271" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://timesofindia.indiatimes.com/india/Operator-on-phone-GoAir-plane-hits-aerobridge/articleshow/48016723.cms&quot; rel=&quot;noreferrer&quot;&gt;Operator on phone, GoAir plane hits aerobridge&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ccahh.gif&quot; alt=&quot;Picture of the part of GoAir Airbus A-320 aircraft&amp;#39;s fuselage that got punctured after being hit by an aerobridge at Chennai airport on Friday morning. Source: DGCA&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is such a 'puncture' repaired? Is the cabin pressurization also affected by such a puncture, and approximately what is the cost incurred to repair such a puncture?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="1467" LastEditDate="2015-07-10T12:41:59.877" LastActivityDate="2016-03-05T23:54:02.557" Title="How is a fuselage 'puncture' repaired?" Tags="&lt;cost&gt;&lt;fuselage&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16762" PostTypeId="2" ParentId="16760" CreationDate="2015-07-10T13:39:33.723" Score="9" Body="&lt;p&gt;In layman's terms, at least on a Gulfstream G450/G550, the cross-feed system allows the engines to be fed from either the left tank, the right tank, or both tanks (one to each engine.) the cross-feed pipes feed into the fuel hoppers, not directly into the other tank. While you can use the cross-feed system to fix a fuel imbalance, doing so would be via using the fuel (in the engines) not actually transferring it from tank to tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The intertank system is a valve and pipe system between the tanks themselves, allowing a fuel imbalance to be fixed by initiating/allowing the transfer of fuel from tank to tank directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My sources were:&lt;br&gt;&#xA;&lt;a href=&quot;http://code7700.com/g450_g550_fuel_system.html&quot; rel=&quot;nofollow&quot;&gt;G450/G550 Fuel System&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://code7700.com/g450_g550_fuel_unbalanced.html&quot; rel=&quot;nofollow&quot;&gt;G450/G550 Fuel Unbalanced&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-07-21T11:01:26.823" LastActivityDate="2015-07-21T11:01:26.823" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16764" PostTypeId="2" ParentId="16761" CreationDate="2015-07-10T13:53:20.363" Score="-4" Body="&lt;p&gt;The outer fuselage is not the pressure hull. The pressurized cabins are a different shell and are inside the fuselage. This kind of damage would have no effect on cabin pressure. Even if the cabin hull had been rent by a hole of this size, the effect would be minor. The pressure hull is actually open to the air anyway. Pumps continuously add air to the pressurized area while air flows out through various points. The hole would have to be much larger to defeat the power of the pumps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make the repair two things need to be done: the larger open hole needs to be patched and the dent and abrasions around the framing member need to be corrected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To repair the larger tear, the sheet metal worker will probably cut it out in a rectangular pattern with rounded corners. Then a backing plate will be fitted to the rear of the panel and welded or brazed or riveted in place (depending on the materials involved). Finally a patch will be made that fits into the rectangular recess exactly. This patch will be welded and/or rivetted to the backing plate. The patch will then be sanded smooth and painted. You will barely be able to tell it is there when it is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To repair the dent, it will first be pulled out by welding a stud onto the dented portion, then the stud will be pulled outwards. This is repeated until the dent has been removed. Then the small abrasion on the dented area and in the vicinity of the framing member will be filled in using a welding machine. The weld will be abrasively smoothed over, then everything repainted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost to do the repair will depend greatly on where and who does it. In the Boston area I would expect it to cost about $3,500.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested in the details of acceptable methods of repair, the FAA provides a manual describing typical methodologies: &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861&quot; rel=&quot;nofollow&quot;&gt;Aircraft Inspection, Repair &amp;amp; Alterations: Acceptable Methods, Techniques &amp;amp; Practices (FAA AC 43.13-1B and 43.13-2B)&lt;/a&gt; . &lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-07-10T15:33:25.950" LastActivityDate="2015-07-10T15:33:25.950" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="16765" PostTypeId="1" AcceptedAnswerId="16770" CreationDate="2015-07-10T14:47:09.973" Score="6" ViewCount="1214" Body="&lt;p&gt;When gliding what are the effects of a crosswind on my glide path angle? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I have head-wind, the minimum flight path angle (usually called &lt;strong&gt;gamma&lt;/strong&gt;) will be lower than the one without crosswind and with an attitude with a larger lift coefficient  Cl than lift coefficient of max efficiency with no wind?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, if I have tailwind &lt;strong&gt;gamma&lt;/strong&gt; will be greater and the Cl will be lower than Cl of max efficiency. Briefly if I have tailwind without engine I can glide much longer, is it right? &lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="5517" LastEditDate="2015-07-10T15:15:02.603" LastActivityDate="2015-07-10T17:15:26.923" Title="What are the effects of crosswind on glide angle?" Tags="&lt;aircraft-performance&gt;&lt;flight-training&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16767" PostTypeId="2" ParentId="16761" CreationDate="2015-07-10T15:20:04.540" Score="7" Body="&lt;p&gt;The first step for repairing damage to a fuselage skin panel is to cut out the damaged area&lt;sup&gt;1&lt;/sup&gt;. Cracks tend to propagate, so an area much larger than the damage will be removed to ensure that all damaged material is removed. The stiffeners that are behind the fasteners will need to be inspected for damage as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A filler plate will be cut to fill the hole in the skin. One or more doubler plates larger than the removed area will then be cut and all plates will be riveted together. The doublers will possibly be on both sides or at least thicker than the surrounding skin. &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/AERO_Q307_article2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;See here&lt;/a&gt; for some examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's likely that a larger repair such as this one will need to be inspected regularly to ensure that the repair holds strength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to tell where exactly this damage is located, most of the aircraft skin is part of the pressure vessel. However, &lt;a href=&quot;https://aviation.stackexchange.com/q/2522/1696&quot;&gt;the airplane is not completely airtight&lt;/a&gt;, so a certain amount of leakage is normal. A hole of this size will probably not prevent the fuselage from pressurizing, though &lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_2294&quot; rel=&quot;nofollow noreferrer&quot;&gt;larger ones will&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost will depend on the extent of the repair, but could be from \$5,000-\$15,000 (300,000-1,000,000 INR) based on &lt;a href=&quot;http://www.rotor.com/rotornews/March15/2015-05-04.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this estimate&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;Actually, the first step in repairing damage to an airplane is consulting the structural repair manual (SRM). This is provided by the manufacturer and describes general methods for repairing minor and typical damage to airplane structure. If the damage is beyond the allowances in the SRM, the manufacturer will be consulted. All of this is to ensure that the repair will meet or exceed the strength and life of the original structure, or if this is not feasible, that the limitations of the repair are documented and understood. Major repairs will require extra inspections to ensure that the structure is still in good shape. &lt;a href=&quot;https://aviation.stackexchange.com/q/6312/1696&quot;&gt;Aircraft skin will not be welded&lt;/a&gt;, since this can cause heat damage to the metal, requires careful skill and care to do properly, and will not hold up well to fatigue.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-10T15:20:04.540" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16768" PostTypeId="2" ParentId="16765" CreationDate="2015-07-10T16:03:10.477" Score="4" Body="&lt;p&gt;In general, wind does not affect the aerodynamics, it mostly affects where you land. So, for example, if you have a tail wind your glide time will be the same, but you will travel farther than if you had a head wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the &quot;minimum flight path angle&quot;, the angle of maximum drag, that is largely irrelevant to actual flight because you never (intentionally) fly at that angle. When gliding, you usually aim at the best glide speed which will take you the farthest, or occasionally at minimum sink rate rate if you want to maximize your time of flight and distance is not a factor.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-10T16:03:10.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16769" PostTypeId="2" ParentId="16761" CreationDate="2015-07-10T17:01:22.450" Score="4" Body="&lt;p&gt;For commercial airliners and most pressurized craft, &lt;a href=&quot;https://aviation.stackexchange.com/a/16767/7629&quot;&gt;fooot's answer&lt;/a&gt; is good. For most light planes, a repair of this type usually boils down to replacing the entire piece of formed sheet metal or fiberglass that was breeched.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An old acquaintance of mine owns a Cessna 150 that she bought from a farmer who'd lost his medical; the plane had been sitting in a field since then until some rednecks came by and took a potshot at the tail with a hunting rifle. She got the plane for a song and also lucked out on a hangar nearby, but the plane couldn't be certified until the dorsal strake that had taken the hit was replaced. From what I gathered it was a fairly simple matter of removing the old pop rivets with an angle grinder and nailsetter, lifting off the old strake, fitting the new one and pop-riveting it back into place, then paint to match. That particular piece was probably the best-case scenario to have to completely replace; most of the rest of the tail is in large sheets and the bullet would have punched clean through two of them requiring a more extensive teardown to remove and replace.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-10T17:01:22.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16770" PostTypeId="2" ParentId="16765" CreationDate="2015-07-10T17:15:26.923" Score="7" Body="&lt;p&gt;Wind affects your flight path angle by affecting how far you travel while you're descending.&lt;br&gt;&#xA;With no thrust from the engine an airplane is falling out of the sky at a roughly constant rate of descent. The wind direction affects the groundspeed, and thus the distance covered between when the engine failed &amp;amp; when the aircraft hits the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is more directly observable from &lt;em&gt;outside&lt;/em&gt; the airplane.&lt;br&gt;&#xA;Consider these 4 scenarios on a post-it note: The airplane has lost its engine, and the pilot is flying at best-glide airspeed while holding a constant magnetic heading (making no wind corrections):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sc8pQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sc8pQm.png&quot; alt=&quot;Post-It Note&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No Wind&lt;/strong&gt;&lt;br&gt;&#xA;The aircraft descends along the no-wind glide path (about 45 degrees in my drawing), and travels in a straight line over the ground (the &quot;ground track&quot;) while doing so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Headwind&lt;/strong&gt;&lt;br&gt;&#xA;The aircraft descends along a steeper glide path (about 60 degrees in my drawing), because while it's still descending at the same rate the headwind is slowing its progress over the ground. Since it's a direct headwind (right on the nose) the ground track is still straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tailwind&lt;/strong&gt;&lt;br&gt;&#xA;The aircraft descends along a shallower glide path (about 30 degrees in my drawing), because while it's still descending at the same rate it has a tailwind, which is making it move faster over the ground. Since it's a direct tailwind the ground track is still straight here too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Crosswind&lt;/strong&gt;&lt;br&gt;&#xA;The aircraft descends along the no-wind glide path (because it has neither a headwind nor a tailwind), but the crosswind pushes the ground track (in this case into the inconveniently-placed tree).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Your endurance (time aloft) will be similarly unaffected: If you've set the aircraft up at its optimum glide angle-of-attack (best glide airspeed) the descent rate is pretty much the same regardless of whether you have a headwind, tailwind, or crosswind. You will fall the same distance in the same amount of time, it's just a matter of how far you travel while you're falling (which determines where you land).&lt;br&gt;&#xA;You can test this for yourself in an airplane by doing engine-out drills: Line up with a headwind, pull the throttle out, and pitch for the aircraft's best glide speed. Note your vertical speed (rate of descent), and then repeat the test in the opposite direction (tailwind) or at 90 degrees to your original course (direct crosswind): The vertical speed will be effectively the same.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-10T17:15:26.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16771" PostTypeId="1" CreationDate="2015-07-10T19:22:08.530" Score="5" ViewCount="204" Body="&lt;p&gt;In various images of the Solar Impulse aircraft, I see the engines mounted in different positions along the wing.  Am I looking at SI 1 vs SI 2, or are the mount positions capable of reconfiguration depending on conditions/experimentation?&lt;/p&gt;&#xA;" OwnerUserId="9311" LastEditorUserId="1696" LastEditDate="2016-07-05T19:30:38.697" LastActivityDate="2016-07-05T19:30:38.697" Title="What is the reason for different engine configurations seen on Solar Impulse?" Tags="&lt;aircraft-design&gt;&lt;solar-impulse&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16772" PostTypeId="2" ParentId="16771" CreationDate="2015-07-10T19:32:59.990" Score="6" Body="&lt;p&gt;&lt;strong&gt;Solar Impulse 1&lt;/strong&gt; had 2 engines &lt;a href=&quot;https://aviation.stackexchange.com/q/7471/1696&quot;&gt;right next to the fuselage&lt;/a&gt;, and the other 2 further out where the wing bends upwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CpULf.jpg&quot; alt=&quot;Solar Impulse I&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Solar Impulse 2&lt;/strong&gt; has a pair of closely spaced engines on each wing, located partway out onto the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gVQzn.jpg&quot; alt=&quot;Solar Impulse II&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-10T19:32:59.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16773" PostTypeId="2" ParentId="1368" CreationDate="2015-07-10T20:20:21.567" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;In class D and E airspace, there is no separation between IFR and VFR&#xA;  traffic.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is not a true or correct statement. In these airspace classes, there is no requirement &lt;em&gt;by ATC&lt;/em&gt; to provide separation between VFR and IFR traffic. There must still be separation in order for flight to be safe, therefore the responsibility to maintain this separation ultimately rests with the pilots of both aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC is responsible for providing IFR-IFR separation in any controlled airspace. VFR pilots, for their part, are required to &quot;see and avoid&quot; other traffic around them. This is half of why the VFR separation minima exists; you as a VFR pilot must have sufficient visibility in all directions to be able to spot other aircraft and maintain a safe distance from them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR pilots have the same &quot;see and avoid&quot; responsibility when operating in VMC; if ATC instructions would cause the pilot to violate separation minima with observed traffic that ATC doesn't seem to know about, the pilot receiving the instruction must respond that he cannot do as instructed because of the observed traffic, which will include a report of its general position. This is the other half of the reason for VFR separation minima; if you're not flying under direct guidance of ATC, other traffic, IFR or VFR, must be able to see and avoid your aircraft, and therefore you have to stay far enough away from clouds that you're either not a danger to anyone travelling through the cloud or around the other side, or they can see you with enough time to maneuver to avoid you if you are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC &lt;em&gt;may&lt;/em&gt; provide separation involving VFR craft in Class D/E airspace as information and workload permit. VFR traffic, while not required to maintain contact with ATC, may still do so, reporting position and altitude (if ATC doesn't have a radar fix) and receiving traffic advisories of anything ATC does know about. This doesn't relieve the VFR pilot's responsibility to see and avoid but it can help him stay aware of the presence of nearby planes. This becomes more important near major airports in dense areas of airspace, which is why Mode C veils exist; while within the veil, aircraft in Class E can be easily seen and their altitude known, even if they aren't talking to ATC. ATC can then advise IFR traffic to maintain separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, in IMC, pilots can't &quot;see and avoid&quot;, therefore VFR flight is illegal and IFR flights have to trust and follow ATC instructions unless anything they might still see or know obviously indicates otherwise.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-10T23:30:28.367" LastActivityDate="2015-07-10T23:30:28.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16774" PostTypeId="2" ParentId="3861" CreationDate="2015-07-10T23:07:27.280" Score="17" Body="&lt;p&gt;There are several big differences between working around a Class B airport versus a Class C.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Explicit clearance required.&lt;/strong&gt; Operation in Class C airspace simply requires establishing two-way contact with the airport approach prior to entry. Now, it's good manners either way to request entry or indicate your plans involve entry; while it's legal to transition Charlie space with just a &quot;handshake&quot;, it's always better when the controller knows what to expect from you while you're in his airspace, so good radio etiquette typically involves an implicit request to enter (giving the controller the opportunity to have you &quot;remain outside&quot; if he can't deal with you in his airspace right now). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Class B airspace, that request is not just a good idea, it's required; you must establish contact, state your intentions and be &quot;cleared Bravo&quot; before you can enter. The nature of class B airports is also such that transitioning GA traffic is often turned away, and if you want to land a GA plane, you probably won't be doing it on the main runways. Class Cs only have one or two runways to begin with, so you might find yourself spaced in between commercial jetliners (in which case you stay high and land deep to avoid the wake). A request to T&amp;amp;G your Piper Cherokee on DFW runway 18R (the opposite side of a five-runway complex from the GA hangars) will be given a curt &quot;one-eight right is full go around to one-seven left&quot; unless it's three in the morning and the controllers are just that bored.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Shape of airspace.&lt;/strong&gt; Class C airspace regions tend to be fairly regular; a 5NM surface cylinder, 10NM 1200' cylinder, and a 700' floor for Class E space underneath in a pattern tailored to the needs of the region. Variations in this pattern are typically increased ceilings through sections of the outer cylinder. Very simple to remember and negotiate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Bravo airspace, it's not so simple, primarily because Class B airspace by definition is for the biggest airport in a region that may have grown up with several. Boston Logan's Class B space is pretty regular, because Logan is pretty much the only thing to worry about in the region; I see three Class D fields underneath Logan's outer Bravo layer and that's pretty much it. However, D/FW's Class B space is much more geometrically complex. Its surface footprint encompasses another major airport (Dallas Love Field, technically class C in size/traffic but too close to DFW to be managed separately) and there are &lt;em&gt;11&lt;/em&gt; fairly busy class Ds in its umbrella, whose controllers and pilots constantly advocate for higher local Bravo floors to allow the airport sufficient control during approach (most flights into and out of somewhere like Addison or Meacham typically end up having to be cleared Bravo anyway, but that requires radio handoffs between one airport's approach and another's tower). LAX's Bravo space isn't even circular, due to the limitations of the urban area, military bases and mountain ranges surrounding the airport. We won't even talk about Washington DC (OK, yes we will; Dulles, Reagan, Baltimore and Andrews AFB all within 50nm of the most heavily defended surface area on the planet; you need a special FAA training course just to fly here).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Radio management and conduct.&lt;/strong&gt; Class B airports are that way because they're big, and they're busy. Austin-Bergstrom Int'l (AUS), a fairly busy Class C, has approach/departure controllers in the Northeast, Northwest and South directions, plus tower and ground control frequencies. When you come in, you contact approach in your general direction, who vectors you in and hands you off to the tower for final. At LiveATC.net there's only one feed for all these frequencies, and if you're familiar with radio chatter you can easily keep track of everything happening around the airport. The controllers and pilots are also fairly casual and jovial with each other (&quot;United 1234, increase rate of climb&quot;, &quot;United 1234 is currently climbing 2600, what works for you?&quot;, &quot;Oh, anything better would be good, 1234&quot;, &quot;Roger, 1234 pulling vertical&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DFW Int'l has 4 approach &quot;feeders&quot; (one per quadrant), 3 approach &quot;finals&quot; (one per landing runway), two towers each with two frequencies, and three ground control frequencies. Each of these controllers are about as busy, radio-wise, as &lt;em&gt;everybody&lt;/em&gt; in Austin, so they don't mess around; they issue quick, curt instructions that can be really hard to catch, and they don't like hearing &quot;say again&quot;. While you're talking to DFW approach, you say what you need to say and keep your thumb off the button otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want jovial, fly into Love Field; everyone associated with that airport is all one big happy Southwest family. I just heard the following burble: &quot;Hello Love, Southwest 123 turning base runway one-three&quot;, &quot;Southwest 123 welcome home, runway one-three-ra-mmm-left cleared to land&quot;, &quot;Aww, you almost said it, 123 runway one-three left cleared in&quot;. They have fun.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Traffic size and density.&lt;/strong&gt; Again, Class B airports are what they are because they handle a lot of really big planes. If I were to try commuting to work by plane from the Mid-Cities over to north of Dallas, I'd have to negotiate DFW's Bravo space (or the class E underneath the northern approach - &lt;em&gt;shudder&lt;/em&gt;) while the overnight jumbos from Lufthansa and Emirates were inbound on 18R. That's just not a good time to be puddle-jumping around Bravo space. Around a Charlie airport I'd probably get away with it, as the jets are smaller and fewer and the tower has more time for me.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-11T01:24:04.893" LastActivityDate="2015-07-11T01:24:04.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16776" PostTypeId="2" ParentId="7582" CreationDate="2015-07-11T00:55:04.597" Score="1" Body="&lt;p&gt;While there are more pollutants than CO, but keeping with CO, if we use 1000kg fuel as typical for a 747 taxi and takeoff, and compare that with 2 miles of automobile driving, I get the CO per passenger is much smaller for the 747:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;747 &#xA;0.05    fuel CO g/kg;&#xA;1000    Fuel used in Taxi-TO (kg);&#xA;50  CO produced (g);&#xA;400 Passengers;&#xA;0.125   g CO/passenger;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAR &#xA;9.4 CO g/mile;&#xA;2   miles;&#xA;18.8    CO Produced (g);&#xA;4   Passengers;&#xA;4.7 g CO/passenger;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the CO produced per passenger is about 40 times greater for an automobile.&lt;/p&gt;&#xA;" OwnerUserId="9300" LastActivityDate="2015-07-11T00:55:04.597" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16777" PostTypeId="1" AcceptedAnswerId="16840" CreationDate="2015-07-11T04:55:30.780" Score="21" ViewCount="1726" Body="&lt;p&gt;What differences in the &quot;stock&quot; production SSJ-100 (as compared to CRJ-900s or EMB-190s), or in US regional airline operations (vs Interjet's success-so-far with the SSJ-100 in intra-Mexico and Mexico-to-US ops) would put the Sukhoi Superjet out of consideration for US regional airline operations?  Would post-sale support be the killer, or would the only thing in the way be the US government not liking it (either by the FAA shooting down the idea, or by way of an exorbitant trade tariff making it more expensive than other options)?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-11-04T18:42:54.813" Title="What aircraft or airline differences would make the Sukhoi Superjet unsuitable for US regional airline operations?" Tags="&lt;airliner&gt;&lt;airlines&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16778" PostTypeId="2" ParentId="9570" CreationDate="2015-07-11T08:45:49.407" Score="3" Body="&lt;p&gt;You have 2 distinct questions. In answer to the &quot;Why do commercial helicopter pilots wear helmets, when instructors and students don't?&quot; as well as the implied &quot;Why do Canadian Pilots Wear them when American pilots do not&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I can tell, a large part of the American industry is either &quot;lower risk&quot;, Multi-engine flight from airport to airport, or passenger oriented, i.e. Tour pilots, Offshore pilots. In Canada, while there are still Tour pilots, and pilots flying airport to airport, both will, over the course of their job, fly over much more remote terrain, routinely preforming off airport landings in remote, unprepared landing spots. One of the techniques used in Canada  more often than other countries is Long Lining. Not only do the doors often come off for better downwards visibility when doing this it also is more risky than normal flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the part of your question regarding why some pilots do not wear helmets, rotary wing aircraft have a significantly higher chance of crashing than a well maintained commercial fixed wing aircraft. As far as American flight instructors not wearing helmets, it is probably down to culture, I have read some people arguing that the instructor wearing a helmet scares potential customers. Inversely I am aware of at least 1 Canadian flight school witch provides students helmets as part of there commercial training. There may also be a link to the fact most Canadian Instructors are experienced Pilots, while the US industry uses mostly brand new pilots as instructors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/9571/1467&quot;&gt;Jamiec&lt;/a&gt;'s Reasons are the answer to the question in your title &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons not to wear a helmet might include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Uncomfortable and/or Hot&lt;/li&gt;&#xA;&lt;li&gt;Cost: about $1500 and up&lt;/li&gt;&#xA;&lt;li&gt;Looks [worry’s about intimidating customers]&lt;/li&gt;&#xA;&lt;li&gt;Simple belief they are not necessary&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9318" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-11T21:09:00.647" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16780" PostTypeId="1" CreationDate="2015-07-11T09:41:33.163" Score="14" ViewCount="7950" Body="&lt;p&gt;Delta has about 800 aircraft for their current operations; how many pilots does the company have? What is a typical or average number of airline pilots employed per aircraft in the fleet?&lt;/p&gt;&#xA;" OwnerUserId="6967" LastEditorUserId="62" LastEditDate="2015-07-11T11:47:14.273" LastActivityDate="2015-07-11T16:29:16.643" Title="What is a typical ratio of airline pilots to aircraft?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16781" PostTypeId="1" CreationDate="2015-07-11T10:09:09.127" Score="-6" ViewCount="401" Body="&lt;p&gt;Is there a way, or an aircraft that can actually perform this? The F35B fighter jet has hovering capabilities. The only &quot;supposed&quot; images of this 1000 mph spin is from NASA, &lt;strong&gt;but the clouds do not move&lt;/strong&gt;, so it is, in most logic; a computer-animated clip.&lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="9105" LastEditDate="2015-07-11T10:29:29.680" LastActivityDate="2015-07-11T16:31:07.383" Title="How high does a F35B Fighter (whilst hovering) have to be to see the earth rotating at 1000/mph?" Tags="&lt;rotorcraft&gt;" AnswerCount="1" CommentCount="14" ClosedDate="2015-07-11T13:34:34.383" ContentLicense="CC BY-SA 3.0" />
  <row Id="16782" PostTypeId="1" AcceptedAnswerId="16786" CreationDate="2015-07-11T11:08:35.267" Score="13" ViewCount="576" Body="&lt;p&gt;I'm currently attempting to write a novel which briefly features a modified B-1B undertaking a risky, highly important mission in support of a Special Access Program. Since a few scenes are set in the cockpit and feature a discussion between the crew, it would be very helpful to know what the ranks of the crew would most likely be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've done a little research via a number of sites and e-book previews but so far I've not turned up much other than at least one Lancer pilot who was a Major but I have no idea how the co-pilot, DSO and OSO would compare in rank, or if B-1B pilots of greater rank than Major would be realistic/believable.&lt;/p&gt;&#xA;" OwnerUserId="9319" LastEditorUserId="7532" LastEditDate="2015-08-01T20:10:45.273" LastActivityDate="2015-08-01T20:10:45.273" Title="What would the ranks most likely be of the crew of a B-1B?" Tags="&lt;military&gt;&lt;crew&gt;&lt;bomber&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16783" PostTypeId="2" ParentId="16781" CreationDate="2015-07-11T11:18:13.127" Score="3" Body="&lt;p&gt;At an absolute fixed position you would see the earth move at 1 inch altitude.  But you would need to traveling 1000 mph relative to the surface of the earth to hold a fixed position relative to the North star.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At lower altitude the atmosphere moves with the earth.  Otherwise we would experience 1000 mph wind on the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a spirited debate on fixed position. And this is physics. To me the intent from the OP was clear - take rotation out of the equation. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At the equator hold a position such that you can draw a straight line&#xA;between you the rotational axis of the the earth and the center of&#xA;the Sun.  To achieve that you would need to travel apx 1000 mph&#xA;relative to the surface of the earth and should be able to see that&#xA;at any altitude.&lt;/li&gt;&#xA;&lt;li&gt;Or directly above the axis (north or south) point directly at the Sun. How high would you need to be see the earth spin below you?  I don't think you would see it spin as it relatively low angular velocity (one rotation every 24 hours).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I agree this is not an aviation question. I did not think it would into this level of physics. I am good with it getting migrated. If an moderator wants to delete my answer I am good with that.  &lt;/p&gt;&#xA;" OwnerUserId="8649" LastEditorUserId="8649" LastEditDate="2015-07-11T16:31:07.383" LastActivityDate="2015-07-11T16:31:07.383" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="16784" PostTypeId="1" AcceptedAnswerId="17654" CreationDate="2015-07-11T15:33:48.903" Score="3" ViewCount="9749" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/LnyOC.gif&quot; alt=&quot;A UFO&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this design, a circular disc (or flying saucer) slightly humped on the top and bottom aerodynamically efficient? And if, we are able to use it for commercial purposes , would they give a better efficiency than existing aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.gizmag.com/go/7710/&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; states that this would be a better design. Is this true?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-09-17T01:59:19.093" Title="Is the commonly assumed UFO (flying saucer) design aerodynamically efficient?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="13" ClosedDate="2015-08-09T04:23:09.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="16785" PostTypeId="2" ParentId="16780" CreationDate="2015-07-11T16:29:16.643" Score="8" Body="&lt;p&gt;A Google search shows United Airlines has 709 aircraft and 12505 pilots for a ratio of 17.6 : 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft was operated 100% of the time, a month's activity (720 hrs) would need 7 pilots pulling 100 hr/month duties, so it's an interesting related question why they need twice this amount. Perhaps there's significant variation in the hours worked by pilots - not all want to work 100 hrs/month, or can be efficiently scheduled to do so because of their home locations etc.&lt;/p&gt;&#xA;" OwnerUserId="9300" LastActivityDate="2015-07-11T16:29:16.643" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16786" PostTypeId="2" ParentId="16782" CreationDate="2015-07-11T19:26:00.570" Score="13" Body="&lt;p&gt;In general, the pilot could be a captain, major, or lt col, the copilot probably a 1lt or captain, and the navs any of the above. For a select crew handpicked for a &quot;fate of the world&quot; mission, you might put 2 instructor pilots together along with two senior navs, so all 4 as lt cols wouldn't be impossible. On the other hand, if the crew is essentially detailed off to be &quot;secret squirrels&quot; for a while, it probably wouldn't be stacked quite that high, so maybe a mix of majors &amp;amp; captains. That happens because it quickly becomes disruptive to take senior guys (tactics officers, instructors, the ops officer or commander, etc) away from their regular squadron jobs for a prolonged period. The more important the mission, the more that disruption is accepted.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-11T19:26:00.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16789" PostTypeId="1" AcceptedAnswerId="16790" CreationDate="2015-07-12T06:02:50.583" Score="11" ViewCount="445" Body="&lt;p&gt;When a new aircraft is developed that requires a new kind of type rating to fly, considering that FAR 61.195(b)(2) and (e) require the instructor giving a type rating (or any sort of instruction) in an aircraft that requires a type rating to hold a type rating in that aircraft, how is the first type rating for that new aircraft type issued?  Is it implicitly acquired by the flight test pilots, who then can give type rating exams and checkrides to other instructor pilots?  Or is there some procedure tucked into a dark corner of FSIMS that is used when &quot;we need a brand new type rating, now what?&quot;&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-07-12T06:21:28.687" Title="How are type ratings created for new aircraft types?" Tags="&lt;flight-training&gt;&lt;pilot-certification&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16790" PostTypeId="2" ParentId="16789" CreationDate="2015-07-12T06:21:28.687" Score="7" Body="&lt;p&gt;Seems you guessed right, actually.  &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.5,Ch9,Sec3&quot;&gt;FSIMS 5.9.3&lt;/a&gt; does indicate that you can get a letter of authorization in lieu of a type rating:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;B.    Requirements for Aircraft Undergoing Certification. During the type certification process, it is sometimes necessary for industry pilots or FAA inspectors with airman certification responsibility to be qualified in a particular aircraft before a pilot certificate type rating designator is established for that aircraft. &lt;strong&gt;In these circumstances, and at the discretion of the manager of the aircraft evaluation group (AEG), an LOA (Figure 5-187) may be issued in lieu of a type rating.&lt;/strong&gt; This LOA and Letter of Application (Figure 5-188) must be in the pilot’s possession when exercising the authorized privileges. The LOA can eventually be surrendered to a district office in exchange for a temporary airman certificate bearing the category, class, and type ratings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-07-12T06:21:28.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16791" PostTypeId="2" ParentId="16735" CreationDate="2015-07-12T09:40:30.540" Score="4" Body="&lt;p&gt;And even, a Hercules can land on ice:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lzzkN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://lockheedmartin.com/content/lockheed/us/products/c130/History/_jcr_content/center_content/image_1.img.jpg/1403022302054.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They where built for landing on ice may sound crazy but they are built for land on all kinds of surfaces &lt;/p&gt;&#xA;" OwnerUserId="8960" LastEditorUserId="3201" LastEditDate="2015-07-16T07:25:15.320" LastActivityDate="2015-07-16T07:25:15.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16792" PostTypeId="1" AcceptedAnswerId="16797" CreationDate="2015-07-12T11:02:49.150" Score="3" ViewCount="2413" Body="&lt;p&gt;Is there an accurate and updated list of aircraft which squawked 7700?&lt;/p&gt;&#xA;" OwnerDisplayName="user9330" LastEditorUserId="7532" LastEditDate="2015-07-12T20:02:55.623" LastActivityDate="2017-05-26T02:44:57.893" Title="Is there a list of aircraft which squawked 7700?" Tags="&lt;emergency&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16793" PostTypeId="1" AcceptedAnswerId="16939" CreationDate="2015-07-12T16:48:05.960" Score="13" ViewCount="667" Body="&lt;p&gt;voretaq7 mentioned the following two months ago &lt;a href=&quot;https://aviation.stackexchange.com/a/14953/167&quot;&gt;in an answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The process of designing a good checklist is an interesting Human Factors problem - there's a lot of literature on it but it's way out of scope for this site. The usual solution to badly designed checklists is that pilots get frustrated and write our own.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Funny he mentioned that, because I'm frustrated with a badly designed checklist and I'm writing my own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are there FAA-specific best practices for creating checklists in general and highlighting memory items in this specific case?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By this I'm referring to underlining, red-boxing, font changes, color changes, and so on.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="1696" LastEditDate="2018-04-11T19:36:50.917" LastActivityDate="2018-06-08T02:40:30.807" Title="Does the FAA have a best practice for highlighting memory items on a checklist?" Tags="&lt;human-factors&gt;&lt;checklist&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16795" PostTypeId="2" ParentId="8252" CreationDate="2015-07-12T18:50:12.997" Score="8" Body="&lt;p&gt;Logically speaking, all cargo holds must be pressurized unless the aircraft flies below 10,000 feet or the type of cargo is restricted to no liquids, and no pressurized liquids like aftershaves, shampoos, medicines etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At higher altitudes the atmospheric pressure drops and if the cargo hold was unpressurized, all such bottles would burst causing possible damage to the cargo and/or aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9335" LastEditorUserId="97" LastEditDate="2015-07-12T20:37:08.730" LastActivityDate="2015-07-12T20:37:08.730" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16796" PostTypeId="1" CreationDate="2015-07-12T19:35:08.360" Score="30" ViewCount="7208" Body="&lt;p&gt;As far as I know at least some (e.g. some Bombardier Dash-8 series) airplanes during takeoff may increase cabin pressure above air pressure on the ground, before starting to decrease it. In one case pressure was increased to around 760 mm Hg (1013 hPa) when pressure on ground was around 730 mm Hg (973 hPa). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this increase of cabin pressure desired for some reason or is it just a side effect of something? And why does it happen? &lt;/p&gt;&#xA;" OwnerUserId="9336" LastEditorUserId="1696" LastEditDate="2015-07-14T15:22:25.417" LastActivityDate="2019-11-23T17:00:53.033" Title="Why is cabin pressure increased above ambient pressure on the ground?" Tags="&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16797" PostTypeId="2" ParentId="16792" CreationDate="2015-07-12T19:58:32.367" Score="7" Body="&lt;p&gt;An ATC facility probably has a method of recording any aircraft they dealt with each day which declared an emergency, via the transponder code or otherwise.  One is probably safe in assuming that this information is passed along up the food chain for some sort of collection at a national level, although such an aggregated list may not be immediately available to the general public.  My first guess is that a FOIA request might be able to get what you're looking for, although if the requested scope is &quot;every emergency aircraft at every facility in the US over the last two decades,&quot; you may be out of luck.  (That would be a huge volume of data anyway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Understand a couple of things about declaring an emergency:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most aren't accompanied by actually squawking 7700.  Of the (relatively few) emergencies that I've declared in a couple decades of military + civilian flying, I can't think of any that required us to change the transponder code -- we declared the emergency with ATC on the radio, kept our assigned squawk, and did what we needed to do.&lt;/li&gt;&#xA;&lt;li&gt;Many aren't related to the aircraft at all.  I had occasion about a year ago to ask our airline safety department what the most common cause was for declared emergencies in our operation, and was told that far &amp;amp; away, sick passengers (medical emergencies) were #1 by a huge margin, and everything else (which includes all the aircraft-related events) was far down in the weeds in comparison. Given that, seeing that aircraft 123XY declared an emergency 5 times last year doesn't necessarily mean that it has had more mechanical issues than its fleetmate 234XY that only did so once; it may just mean that 123 got more than its share of sick passengers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In fact, in airline operations at least, mechanical issues are &lt;strong&gt;&lt;em&gt;almost&lt;/em&gt;&lt;/strong&gt; always caught on the ground, so an aircraft with &quot;gremlins&quot; will usually manifest them in terms of maintenance delays and cancellations, rather than in-flight emergencies.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-12T19:58:32.367" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16799" PostTypeId="2" ParentId="16796" CreationDate="2015-07-12T20:32:48.977" Score="38" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cjLc6.png&quot; width=&quot;630&quot; height=&quot;18&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Short answer&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of pre-pressurization is to avoid discomfort for passengers and crews during takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By storing air in the cabin before the aircraft rotation or landing, the pressurization controller is able to smooth out:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The variations of bleed air supply when the engines deliver the highest thrust and need all available air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The variations in both air supply and air release, due to the aircraft leaving or entering the ground effect. In particular this ground effect would force air into the cabin through the forward outflow valve when the angle of attack is increased for takeoff rotation or landing flare out.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However pre-pressurization involves relatively limited pressure differentials.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;236 ft for a B737-NG (9 hPa). &lt;/li&gt;&#xA;&lt;li&gt;140 ft for a &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=Dash8-200-300-Air_Cond_and_Press.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dash8-200-300&lt;/a&gt; (5 hPa).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The case you mention seems ways higher with 40 hPa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2yyir.png&quot; width=&quot;630&quot; height=&quot;18&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pressurization system&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The source of cabin air for the aircraft is commonly bleed air from the engine compressor stages. Air is sent to packs for conditioning and enters the cabin (see a more complete description in &lt;a href=&quot;https://aviation.stackexchange.com/questions/24809/why-is-air-mixed-with-bypass-air-on-the-a-c-of-an-aircraft/24820#24820&quot;&gt;this answer&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pm6zR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pm6zR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(B737-800, &lt;a href=&quot;http://tnumks.blogspot.fr/2014/02/air-systems-bleed-air-system-b737-ng.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bleed air pumped into the cabin then escapes it by one or two configurable exits, the &lt;em&gt;outflow valves&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GO9MT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GO9MT.jpg&quot; alt=&quot;Outflow Valve, B737 NG&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Outflow valve (and near to it the safety valve) on a Boeing 737-NG. &lt;a href=&quot;https://www.researchgate.net/publication/261178578_Low_noise_outflow_valve_installed_in_Boeing_737NG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cabin pressure is obtained by controlling the rates the air enters and leaves the cabin. This is indeed the job of the pressurization controller. This job is more difficult at takeoff and landing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Air taken from the compressor is not used for the production of thrust, which can be a problem when thrust is critically required, e.g. for takeoff roll and rotation, or go-around. For these sequences, bleed air may be not available, or may be delivered at reduced or unstable rates. Normal bleed air delivery capability is restored after takeoff when the engines need less air. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The ambient pressure around the aircraft is subject to variations when the aircraft rotates and leaves the benefit of the ground effect, and also when it enters this effect before the flare. So the differential pressure at the outflow valve varies as well as the bleed air supply, and both need to be compensated too.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pre-pressurization&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unmanaged variation of bleed air supply or cabin air outflow create &lt;em&gt;air bumps&lt;/em&gt; in the cabin. To avoid discomfort, on some aircraft the cabin is &lt;em&gt;pre-pressurized&lt;/em&gt; at a pressure slightly higher than the ground ambient pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pre-pressurization occurs during the takeoff roll and shortly before landing. It creates a stock of air the pressurization controller can use to smooth out bleed air bumps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.737ng.co.uk/b737-800%20FCOM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;B737-800 FCOM&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The air/ground safety sensor signals whether the airplane is on the&#xA;  ground or in  the air. On the ground and at lower power settings, the&#xA;  cabin is depressurized by  driving the outflow valve to the full open&#xA;  position.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The cabin begins to pressurize on the ground at higher power settings.&#xA;  The controller modulates the outflow valve toward close, slightly&#xA;  pressurizing the cabin. This ground pressurization of the cabin makes&#xA;  the transition to pressurized flight more gradual for the passengers&#xA;  and crew, and also gives the system better response to ground effect&#xA;  pressure changes during takeoff.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This additional amount of pressure mustn't compromise the ability to quickly open the doors in case of emergency, so pressure differential is limited. On a B737-NG, the differential is 0.125 PSI (9 hPa). This is equivalent to an altitude 236 ft below the runway. The system has a fail-safe mode which automatically opens the outflow valves quickly after the aircraft has landed (unless the &lt;a href=&quot;https://aviation.stackexchange.com/q/60501/3201&quot;&gt;Ditching switch&lt;/a&gt; has been pressed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the aircraft is airborne, or has landed, the pressurization system releases air previously stocked, to recreate a smooth altitude increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of completeness: The cabin will not &quot;climb&quot; or &quot;descend&quot; as fast as the aircraft, and will have its ceiling at 8,000 ft to maintain oxygen pressure at a safe level to breath without a mask.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cabin pressure vs. atmosphere pressure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a representation of the pressure differential during a flight (with the takeoff/landing highlighted. Note the cabin (dashed line) &quot;is lower&quot; than the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G0XX4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G0XX4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://viditelnykocour.inet-box.cz/viditelny_kocour/cockpit/overhead/aircondpress.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-23T17:00:53.033" LastActivityDate="2019-11-23T17:00:53.033" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16800" PostTypeId="1" AcceptedAnswerId="16801" CreationDate="2015-07-12T20:49:47.913" Score="10" ViewCount="1210" Body="&lt;p&gt;Inspired by this &lt;a href=&quot;https://i.imgur.com/my4FELj.gifv&quot; rel=&quot;noreferrer&quot;&gt;Grand Theft Auto gif&lt;/a&gt;, an aircraft with its engines initially idling is dropped from a high altitude (such as from the top of a building) with no or minimal horizontal velocity. Can it successfully throttle up and fly to safety? How about for&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A fixed-wing aircraft, and&lt;/li&gt;&#xA;&lt;li&gt;A helicopter&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9338" LastEditorUserId="9338" LastEditDate="2015-07-13T10:30:03.860" LastActivityDate="2016-03-12T22:15:53.970" Title="Can a free-falling aircraft with no horizontal (or minimal horizontal velocity) start up and fly to safety?" Tags="&lt;helicopter&gt;&lt;aerobatics&gt;&lt;fixed-wing&gt;" AnswerCount="4" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16801" PostTypeId="2" ParentId="16800" CreationDate="2015-07-12T21:39:50.983" Score="13" Body="&lt;p&gt;Rather obviously, both of these situations are far from likely to occur. As a result, the following is just idle (but hopefully informed!) speculation — I don't recommend experiments! &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;I'm going to be a little bit cheeky in answering this question -- you've asked if it's possible for “a &lt;em&gt;fixed wing&lt;/em&gt; aircraft to [...] get the engines up to speed and fly off.” I'll answer “&lt;strong&gt;Yes&lt;/strong&gt;, but it depends on the aircraft.” For the fixed wing aircraft I usually fly, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASK_21&quot; rel=&quot;noreferrer&quot;&gt;K-21 glider&lt;/a&gt;, getting the engines up to speed is a doddle — it’s powered by gravity (and essentially stays aloft by the sun). What matters here is the &lt;a href=&quot;http://en.wikipedia.org/wiki/Stall_speed&quot; rel=&quot;noreferrer&quot;&gt;stall speed&lt;/a&gt; of the aircraft in question, and how quickly the pilot could recover from the ‘upset’ of being kicked off the top of a tall building, and land somewhere sensible (which can only realistically happen once the aircraft is not stalled). If the relative airflow over the K21’s wings is about 35 knots (40 mph, 65 kph) or greater, they generate enough lift to keep it airborne (and going about 30 m forward for every meter down). &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If we assume that you’re a free-falling body, Newton (in the form of $v=u+at$) says that it’ll take about 1.8 seconds to reach that speed, and you’ll fall ($v^2=u^2+2as$) about 16 meters during that time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, you’ll be pointing nose down at the ground, accelerating, and needing to do something about it — which will take time, and, more importantly distance. But, in the grand scheme of sky-scrapers, mountains and cliffs, 16.2 m isn’t that high. Incidentally, for this reason, &lt;em&gt;bungee launching&lt;/em&gt; is a traditional method of getting gliders airborne in parts of the world with big hills — a team of runners using glorified elastic bands shoot brave pilots into the blue yonder, as illustrated by the picture below (at the Long Mynd). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/eTs3e.jpg&quot; alt=&quot;Bungee launched glider at the Long Mynd, UK&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, given that a &lt;em&gt;hill&lt;/em&gt; is enough height for a sailplane to take off, possibly for a few hours on a good day, I’m reasonably sure that something like the John Hancock Centre would provide more than enough time for a pilot to recover from an odd attitude, loop forward to a nose-down dive, recover smoothly from it, and fly away (from the big building behind him).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gif you linked to featured what looked a lot like a small private jet. I defer to the others on this site with a lot more turbofan experience than I, but I’ll just say this: given an hour that I spent in a 777 simulator, &lt;strong&gt;twenty minutes&lt;/strong&gt; were spent going from “cold and dark” to pushback, I suspect you’d have a much harder time doing it. Of course, rapid engine starts are possible in some aircraft. It depends a lot on the exact circumstances you're asking (and passenger jets tend not to be designed for inverted flight, for example). &lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;By all accounts, this situation isn’t probably going to be very recoverable. If the blades are stationary when the aircraft starts falling, they’ll be fully stalled, resulting in a low-rotor RPM stall, which, depending on the brand of helicopter may not “be recoverable” (e.g., even with a working engine, Robinson helicopters are generally not recoverable from a very low rotor RPM stall). Autorotation is the driven motion of the rotor by the air falling through it, but, as pointed out, fully-stalled blades at any angle will not generate much torque (or lift), and therefore be unable to arrest the rate of descent of the falling aircraft. I presume that the only exception would be a fuselage that could provide lift through another means, such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;noreferrer&quot;&gt;V-22 Osprey&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7499" LastEditorUserId="774" LastEditDate="2015-08-03T03:13:53.800" LastActivityDate="2015-08-03T03:13:53.800" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16802" PostTypeId="1" AcceptedAnswerId="16803" CreationDate="2015-07-13T01:33:16.963" Score="13" ViewCount="1607" Body="&lt;p&gt;I was watching James May's Toy Stories, particularly the one where they &lt;a href=&quot;https://en.wikipedia.org/wiki/James_May%27s_Toy_Stories#Flight_Club&quot; rel=&quot;noreferrer&quot;&gt;try to fly a glider across the English Channel&lt;/a&gt;.  In the middle of the episode they mention a glider that was used for training in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Royal_Air_Force&quot; rel=&quot;noreferrer&quot;&gt;RAF&lt;/a&gt; during the 1950s.  It was called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Slingsby_Swallow&quot; rel=&quot;noreferrer&quot;&gt;Slingsby Swallow&lt;/a&gt;, and it looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ksRXd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I saw those pieces of metal coming out of the wings I was...surprised.  At first I thought they were split flaps but then I found another picture and became even more confused:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NysdG.jpg&quot; alt=&quot;enter image description here&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The devices are clearly coming out of the top and bottom of the wing, not the trailing edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know what these are and what they are used for on the Slingsby Swallow (or any other aircraft the employs a similar device)?  My only guess is that they are some sort of spoiler that may reduce lift to help get the glider on the ground...but I'm uncertain.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="8547" LastEditDate="2015-07-13T13:00:47.733" LastActivityDate="2015-08-30T06:26:38.100" Title="What are the vertical pieces of metal on the Slingsby Swallow wing for?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;flight-controls&gt;&lt;glider&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16803" PostTypeId="2" ParentId="16802" CreationDate="2015-07-13T02:33:30.980" Score="20" Body="&lt;p&gt;You're correct -- they're speedbrakes, often referred to as spoilers, and are retracted when striving for efficient flight, but are generally extended in the landing pattern so that you have correction available if you start to get slightly low.  Also frequently extended when the glider is left on the ground to reduce the effect of gusty winds &amp;amp; the likelihood that they would lift a wing.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-13T02:33:30.980" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16805" PostTypeId="2" ParentId="14971" CreationDate="2015-07-13T07:32:53.073" Score="3" Body="&lt;p&gt;Rear launching missile might be possible, but I think if you have the option of adding another missile, I imagine most pilots would prefer to have it forward facing so they can use it to aggressively attack and destroy an opponent. Dogfight tactics traditionally favour aggressive offensive tactics as opposed to defensive ones, and therefore forward pointing weapons makes more sense. If your enemy is behind you, you've already screwed up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the French actually managed to destroy a target behind the launching aircraft with a MICA missile (unsure if it was the radar guided or IR guided variant) &#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/MICA_(missile)#cite_note-4&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/MICA_(missile)#cite_note-4&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately the original source is a dead link.&lt;/p&gt;&#xA;" OwnerUserId="8743" LastActivityDate="2015-07-13T07:32:53.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16806" PostTypeId="2" ParentId="16802" CreationDate="2015-07-13T08:01:38.980" Score="7" Body="&lt;p&gt;If you observe the image below, in the marked areas, you'll see a rectangular patch (it's very faint): &lt;img src=&quot;https://i.stack.imgur.com/tPbI0.jpg&quot; alt=&quot;Slingsby Swallow LR by Borderglider - Own work. Licensed under CC BY 3.0 via Wikimedia Commons&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the places over and below the wing where the &quot;Devices&quot; you mentioned are housed. These devices are called &lt;strong&gt;Dive Brakes&lt;/strong&gt;. They are used as spoilers to increase the drag while flying so as to lose altitude by increasing the drag (and hence the name). These can be retracted when not required, and deployed when required. The patches in the image are the housings where these are actually deployed from and retracted back to.&#xA;And from &lt;a href=&quot;https://aviation.stackexchange.com/a/16803/1467&quot;&gt;Ralph J's answer&lt;/a&gt;, they can be left deployed when the plane is on ground, as its a very light plane and gusts and winds can actually cause the plane to lift if enough drag is not there.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-13T08:14:35.213" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16807" PostTypeId="1" AcceptedAnswerId="16809" CreationDate="2015-07-13T08:14:02.947" Score="2" ViewCount="1819" Body="&lt;p&gt;Pilots since world wars have been wearing g-suits in fighter planes to minimize the effect of high g encountered by them during close maneuvers. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How do g-suits help in minimizing the effect of high g's on the pilots?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the maximum g that a g-suit could handle properly?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-13T09:01:50.117" Title="What is the working principle of g-suits?" Tags="&lt;pilots&gt;&lt;pilot-technique&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16808" PostTypeId="1" AcceptedAnswerId="16815" CreationDate="2015-07-13T08:18:44.207" Score="36" ViewCount="49501" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/RgIyo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde#/media/File:ConcordeCockpitSinsheim.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was this cockpit much more complex than any other modern day aircraft or a fighter jet? It looks to have many more buttons and controls, and very small (interesting) screens. Also, its steering was much different than you would see in any other aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2019-01-21T21:21:29.973" LastActivityDate="2019-03-12T03:53:01.830" Title="Why was Concorde's cockpit so complex?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;&lt;concorde&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16809" PostTypeId="2" ParentId="16807" CreationDate="2015-07-13T08:22:12.963" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How do g-suits help in minimizing the effect of high g's on the pilots?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;G-suit create extra external pressure on the limbs (legs in particular) to prevent the blood to stagnate far from the heart. In normal conditions specific &lt;a href=&quot;https://en.wikipedia.org/wiki/Skeletal-muscle_pump&quot; rel=&quot;nofollow noreferrer&quot;&gt;biological&lt;/a&gt; &lt;a href=&quot;http://www.cvphysiology.com/Cardiac%20Function/CF017.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;systems&lt;/a&gt; automatically return the blood from the extremities to the heart, but when subjected to high G loads these systems fail, as they are not designed for such conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By creating pressure on the body the G-suit &lt;strong&gt;alleviates&lt;/strong&gt; the G load perceived by the body.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the maximum g that a g-suit could handle properly?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The main limitation is not only the amount of Gs, but for how long the human body can sustain them (spoiler alert: not much)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wfvBm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;https://en.wikipedia.org/wiki/G-force#Human_tolerance_of_g-force&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see the Gs usually experienced in a fighter aircraft (blue line, see diagram on top right) cannot be sustained much beyond 3 seconds if they are of even moderate intensity. The G-suits help the body resist slightly longer.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-07-13T09:01:50.117" LastActivityDate="2015-07-13T09:01:50.117" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16810" PostTypeId="1" CreationDate="2015-07-13T08:32:26.517" Score="2" ViewCount="126" Body="&lt;p&gt;&lt;a href=&quot;http://www.spikeaerospace.com/s-512-supersonic-jet/&quot; rel=&quot;nofollow&quot;&gt;Spike Aerospace&lt;/a&gt;  claims to have designed an aircraft called S-512, with maximum speed of 1.8 mach and cruise speed of 1.6 mach, speaking about the notable changes in the aircraft, Spike Aerospace &lt;a href=&quot;http://www.foxnews.com/travel/2015/07/08/spike-aerospaces-s-512-supersonic-jet-promises-to-fly-from-new-york-to-london/?cmpid=cmty_twitter_fn&quot; rel=&quot;nofollow&quot;&gt;says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“The new delta wing of the S-512 delivers high aerodynamic efficiency and improved flight performance in both low-speed flight and supersonic cruise,” “The &lt;strong&gt;highly swept leading-edge&lt;/strong&gt; reduces wave drag and consequently reduces fuel burn and increases range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does a &lt;em&gt;highly swept leading-edge&lt;/em&gt; helps?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-07-13T14:54:40.287" LastActivityDate="2015-07-13T14:54:40.287" Title="How does a 'Highly Swept leading-edge' delta wing reduces fuel burn and increases range?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-07-13T16:50:58.360" ContentLicense="CC BY-SA 3.0" />
  <row Id="16811" PostTypeId="2" ParentId="16808" CreationDate="2015-07-13T08:42:15.927" Score="21" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why was this cockpit much more complex than any other modern day aircraft or a fighter jet. It looks to have much more buttons and controls, and very small(interesting) screens&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The cockpit is much more complex than any other modern day aircraft or a fighter jet because it is an &lt;strong&gt;Analogue&lt;/strong&gt; cockpit. Concorde was designed in the 60's and at that point of time the technology was not simply advanced enough to have LCD screens in the cockpit, and neither capacitive/resistive touchscreens were around the block. Hence this left switches/levers as the only options with the designers and that is why you see a lot of these in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, Concorde had a lot of additional controls like the Droop Nose and the Afterburners for supersonic flight. Such additional controls would need more switches, and increase the complexity of the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, since the on board computers were not very advanced at that point of time (even though Concorde had one of the most intelligent computers at the time of its inception), hence the flight engineer and the cabin crew had to monitor and control a lot of systems manually, and since the cabin was very cramped (as can be seen in the image), this gave a very claustrophobic and complex look to the cabin.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-07-13T09:33:53.837" LastActivityDate="2015-07-13T09:33:53.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16812" PostTypeId="2" ParentId="16807" CreationDate="2015-07-13T08:50:00.093" Score="2" Body="&lt;p&gt;Additionally to what @Federico wrote, g-suits press the legs by using inflatable sacs sewed in the suit. The suit is connected to a valve on the aircraft (or spaceship). When g forces increase, the valve pushes more air to the sacs and inflates them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the limit, I think it is 9 g's but I don't have any citations. Also bear in mind that g limit has to do with other parameters as well, such as cockpit and seat design like HAC (high acceleration cockpit).&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-07-13T08:50:00.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16814" PostTypeId="1" AcceptedAnswerId="16817" CreationDate="2015-07-13T09:32:25.303" Score="14" ViewCount="2829" Body="&lt;p&gt;As seen in the picture below, Concorde used to have a droop nose which would be deployed during takeoff/landing and would be retracted to the normal position while in cruise (do reduce drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Concorde with a droop Nose deployed&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2PzMW.jpg&quot; alt=&quot;Concorde with a droop Nose deployed&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Concorde in normal configuration&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wHotG.jpg&quot; alt=&quot;Concorde in normal configuration&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the wiki page on Concorde, this Droop Nose was added in the later versions of Concorde when the authorities raised questions about the restricted view which was available to pilots during landing/take off at very high angles of attack (which was required for the Concorde).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What are the other possible solutions which could have been employed instead of the droop nose to tackle to the restricted view from the cockpit?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Why did Concorde had to land and take off at higher than normal angle of attacks?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How did the Droop nose actually work? (Which mechanism was used to deploy and retract it)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2017-03-03T08:25:29.337" LastActivityDate="2019-04-06T22:53:19.453" Title="Why did the Concorde require a droop nose and how did it work?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;takeoff&gt;&lt;concorde&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16815" PostTypeId="2" ParentId="16808" CreationDate="2015-07-13T09:44:37.007" Score="53" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why was this cockpit much more complex than any other modern day aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Firstly, as others have noted, you imply Concorde was modern when you compare it with &quot;other modern&quot; aircraft. OK, it was a &quot;jet-age&quot; aircraft, but it wasn't a 21st Century design. it was designed before &quot;glass cockpits&quot; were possible, in the 1960s. There were no real multifunctional displays then, so there had to be a switch or dial for every possible action and every possible parameter the pilots might need to know about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main difference is probably the flight engineer's panel on the right. Modern aircraft have two pilots in the cockpit and no flight engineer. I imagine that increased automation in engine controls mean that the engine management by the crew is much simpler and requires fewer controls and dials. These are now typically located in the center of the main instrument panel above the thrust levers etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison, here's (a somewhat poorly stitched panorama of) a 747 cockpit&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://airandspace.si.edu/explore-and-learn/multimedia/detail.cfm?id=1532&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OwP65.jpg&quot; alt=&quot;747 cockpit&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image by Eric Long, National Air and Space Museum, Smithsonian Institution&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and a rather better photo of a 747-300 cockpit (though lower central controls are obscured) ...&#xA;&lt;a href=&quot;https://www.flickr.com/photos/30347085@N02/4013338059/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/61YIe.jpg&quot; alt=&quot;747 cockpit&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image &amp;copy; aroosh&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;or a fighter jet?&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A lot of the controls and instruments are duplicated in a two-pilot cockpit. In a fighter jet, you only see one set of instruments and controls. Also a one-engine plane will have a quarter the engine controls of a four engine plane. Fighters probably lack an APU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although fighters have additional switches etc for armaments, airliners have additional switches etc for passenger related facilities (seatbelt lights, a/c? etc), security (cockpit door), cabin-crew comms and so on. They also may have more fuel tanks and maybe more means to move fuel around in flight to trim the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;It looks to have much more buttons and controls,&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Modern glass cockpits just hide all that complexity, just imagine you could rotate 90% of what you see out of view.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;and very small(interesting) screens.&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are no screens at all. There is a colourful moderately-complex artificial horizon instrument which also shows aircraft attitude and a few other things. The visual part is essentially mechanical rather than created by a light-emitting digital display.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Also, its steering was much different than you would see in any other aircraft.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The shape of the control yoke may be slightly unusual but it operates the same was as any more common yoke design. You push it forward and back to control the pitch using the elevator (or elevons) and you rotate the top part left or right to control roll using ailerons (or equivalent control surfaces). There are buttons on the had grips to control a few functions. I think the shape was partly to make it easier to get in and out of the seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heres a similar yoke design in an Embraer ERJ-145LR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/US-Airways-Express/Embraer-EMB-145LR-(ERJ-145LR)/0768651/M/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nOd2w.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image &amp;copy; Micheal Catchpole&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-07-13T15:02:09.000" LastActivityDate="2015-07-13T15:02:09.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16816" PostTypeId="1" AcceptedAnswerId="16843" CreationDate="2015-07-13T11:51:04.337" Score="10" ViewCount="904" Body="&lt;p&gt;Let's say you have a demilitarized A-10 (this isn't too farfetched an idea, as this &lt;a href=&quot;http://www.ias.sdsmt.edu/institute/t28/Next-Generation_files/Next-Generation.pdf&quot; rel=&quot;noreferrer&quot;&gt;SDSM&amp;amp;T proposal for a replacement thunderstorm research aircraft&lt;/a&gt; demonstrates).  With an empty weight twice the 12,500 pound limit, it &lt;em&gt;clearly&lt;/em&gt; requires a type rating; however, there was only one two-seat A-10 (the YA-10B) ever built, and it likely isn't airworthy any longer.  (It is on static display at Edwards AFB.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, how would you train a civil pilot to get their A-10 type rating?  Would it be a simulator-only exercise, or a long ground school followed by a solo signoff?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-07-13T22:19:09.703" LastActivityDate="2015-07-23T20:54:28.943" Title="How is a type rating administered for aircraft that do not comply with 91.109?" Tags="&lt;flight-training&gt;&lt;pilot-certification&gt;&lt;type-ratings&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16817" PostTypeId="2" ParentId="16814" CreationDate="2015-07-13T12:06:05.850" Score="12" Body="&lt;p&gt;1) Though already mentioned that this might be too broad, I would dare to guess a properly fitted camera could do the trick. But I doubt that this would be effective considering the technology of the era that Concorde was developed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Concorde due to its design for supersonic speeds, it was generating too little lift at low speeds (like those needed for landing). So they had to take into advantage another way of producing lift: &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_lift&quot;&gt;vortex lift&lt;/a&gt;. In order to produce vortex lift, you need relatively high angles of attack and consequently high pitch attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) I cannot answer this since I am not an engineer. Though with little googling I found &lt;a href=&quot;http://www.concordesst.com/nose.html&quot;&gt;this&lt;/a&gt;. It seems to be very detailed, with photos of the lever and diagrams of the mechanism.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-07-13T12:06:05.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16818" PostTypeId="1" AcceptedAnswerId="16824" CreationDate="2015-07-13T12:30:57.753" Score="16" ViewCount="31719" Body="&lt;p&gt;When reading aviation literature, it's common to find references to &lt;strong&gt;Zulu Time&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is &lt;strong&gt;Zulu Time&lt;/strong&gt;?&lt;/li&gt;&#xA;&lt;li&gt;Why does aviation use Zulu Time instead of the local time?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="43" LastEditDate="2015-07-13T13:53:08.493" LastActivityDate="2018-06-28T03:57:53.470" Title="Why does aviation use Zulu time instead of the local time?" Tags="&lt;time&gt;" AnswerCount="5" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16819" PostTypeId="2" ParentId="16818" CreationDate="2015-07-13T12:38:16.817" Score="5" Body="&lt;p&gt;Zulu time, used in aviation quite often, is another name for UTC (Coordinated Universal Time (French: temps universel coordonné)). It is the primary time standard by which the world regulates clocks and time. It is, within about 1 second, mean solar time at 0° longitude; it does not observe daylight saving time. It is one of several closely related successors to Greenwich Mean Time (GMT). For most purposes, UTC is considered interchangeable with GMT, but GMT is no longer precisely defined by the scientific community.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the second part of your question : Its called Zulu time as UTC does not have daylight savings, hence Zero hour shift. Now Zero starts with Z and NATO call-sign for Z is Zulu. Hence the name.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="8547" LastEditDate="2015-07-13T12:54:01.110" LastActivityDate="2015-07-13T12:54:01.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16820" PostTypeId="2" ParentId="16818" CreationDate="2015-07-13T12:44:09.673" Score="11" Body="&lt;p&gt;Zulu time is &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_Universal_Time&quot;&gt;UTC time&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for the name zulu is because there is a hour shift of Zero sometimes denoted with a &lt;em&gt;Z&lt;/em&gt; and in the nato alphabet Z is Zulu.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many times a route will cross timezone so to avoid confusion about which timezone a time is in controllers and pilots will use zulu time by default. It also avoids daylight savings issues.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="64" LastEditDate="2015-07-13T15:30:58.853" LastActivityDate="2015-07-13T15:30:58.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16821" PostTypeId="1" CreationDate="2015-07-13T12:57:56.733" Score="16" ViewCount="3914" Body="&lt;p&gt;Large flock of birds when migrating usually fly in an arrow formation, which helps the birds to save energy while flying the same distance as compared to a situation when the birds are not in a group. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the physics behind this?&lt;/li&gt;&#xA;&lt;li&gt;What is the significance of the specific flying formation?&lt;/li&gt;&#xA;&lt;li&gt;Can this be applied on airplanes (given the fact that anything analogous to engine exhaust is not present in birds)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="52" LastEditDate="2015-07-13T13:23:38.503" LastActivityDate="2019-08-02T01:34:44.270" Title="How do planes benefit from flying in formation?" Tags="&lt;flying-in-formation&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16822" PostTypeId="2" ParentId="16808" CreationDate="2015-07-13T12:59:14.757" Score="29" Body="&lt;p&gt;As others already said, the keyword in your post is &quot;modern&quot; and Concorde is not one. You compare dissimilar things. Try comparing with something similar, a Boeing 747-200 cockpit for example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iTl12.jpg&quot; alt=&quot;B742 cockpit&quot;&gt;&#xA;Copyright owner: &lt;a href=&quot;https://www.flickr.com/photos/apenny/3226329374&quot; rel=&quot;noreferrer&quot;&gt;Achim Pfennig&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now compare the pictures. You will notice the same level of complexity in the cockpits. Sure there will be differences if you make an in-depth research, but bottom line is that analogue cockpits look &quot;cluttered&quot; compared to the modern and &quot;sleek&quot; glass cockpits.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-07-13T12:59:14.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16824" PostTypeId="2" ParentId="16818" CreationDate="2015-07-13T13:52:34.733" Score="31" Body="&lt;p&gt;&lt;strong&gt;Zulu&lt;/strong&gt; means the letter &lt;strong&gt;Z&lt;/strong&gt; in radio communication. The letter &lt;strong&gt;Z&lt;/strong&gt; designates UTC time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is actually &lt;a href=&quot;http://www.timeanddate.com/time/zones/&quot; rel=&quot;nofollow noreferrer&quot;&gt;a list of time zones&lt;/a&gt; for each letter of the alphabet (except &lt;strong&gt;J&lt;/strong&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Alpha time zone: UTC + 1&lt;/li&gt;&#xA;&lt;li&gt;Bravo time zone: UTC + 2&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;li&gt;India time zone: UTC + 9&lt;/li&gt;&#xA;&lt;li&gt;Kilo time zone: UTC + 10&lt;/li&gt;&#xA;&lt;li&gt;Lima time zone: UTC + 11&lt;/li&gt;&#xA;&lt;li&gt;Mike time zone: UTC + 12&lt;/li&gt;&#xA;&lt;li&gt;November time zone: UTC - 1&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;li&gt;X-ray time zone: UTC - 11&lt;/li&gt;&#xA;&lt;li&gt;Yankee time zone: UTC - 12&lt;/li&gt;&#xA;&lt;li&gt;Zulu time zone: UTC + 0&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, the other time zones are seldom referenced in aviation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Why do we use UTC time instead of local time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because flights often cross time zones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine this: the time now is 11:59. We will takeoff at 12:30 and fly west. Afterwards, at around 11:48, we will be 15 nautical miles away from the airport.....................Huh?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even more confusing: We takeoff at 12:30 and land at 13:00 ==&gt; we only need 30 minutes of fuel. Wrong! We actually cross a time zone and the actual flight time is 90 minutes. But we've taken off with 60 minutes less fuel than we need. What do we do?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2018-06-28T03:33:07.450" LastActivityDate="2018-06-28T03:33:07.450" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="16825" PostTypeId="2" ParentId="16821" CreationDate="2015-07-13T13:53:39.330" Score="10" Body="&lt;p&gt;Canada Geese are famous for taking advantage of this phenomenon-- they use the wingtip vortices caused by the bird right in front of them, to decrease drag during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see &lt;a href=&quot;https://en.wikipedia.org/wiki/V_formation&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia&lt;/a&gt; for some information regarding &quot;V&quot; formation&#xA;and &lt;a href=&quot;http://aviationweek.com/blog/c-17s-go-surfing-save-fuel&quot; rel=&quot;nofollow noreferrer&quot;&gt;aviationweek&lt;/a&gt; for a relevant USAF experiment involving C17 aircraft.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="34686" LastEditDate="2019-08-02T01:34:44.270" LastActivityDate="2019-08-02T01:34:44.270" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="16827" PostTypeId="2" ParentId="16821" CreationDate="2015-07-13T14:14:36.263" Score="20" Body="&lt;h1&gt;Energy saving&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The wing creates lift, which is upward force on the wing. According to principle of action and reaction, there must be a downward force acting on the air. This force creates a downwash behind the wing. As the accelerated air interacts with the still air further away it turns to the sides and back up, creating a slight &lt;em&gt;upwash&lt;/em&gt; outside of the wingtips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying in this upwash adds a bit of lift on the next flying thing which in turn means it can fly at slightly lower angle of attack and have less induced drag. This recovers some energy from the wake vortex that would otherwise be dissipated as heat.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Birds&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Migratory birds use the typical V formation to take advantage of this, each bird flying aft and to the side of the previous. Since the leader is not getting any advantage, the birds usually take turns in leading the flock.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Aircraft&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I have however not heard of this being done with aircraft for energy purposes beyond experiments. Military aircraft usually use similar V formation, but for different reasons. They need to fly in group, because they need to provide mutual defence. And then the V formation is used during cruise to and from target area simply because in it the wingmen see the leader while remaining clear of their downwash and wake turbulence.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-07-13T18:42:57.287" LastActivityDate="2015-07-13T18:42:57.287" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="16828" PostTypeId="1" AcceptedAnswerId="16830" CreationDate="2015-07-13T14:18:40.113" Score="0" ViewCount="3338" Body="&lt;p&gt;Can anyone explain how to find the wing chord of the aircraft Aero A.10? Given Wing Span = 46.6 ft and Wing Area = 549 sqft. Thanks&lt;/p&gt;&#xA;" OwnerUserId="9346" LastEditorUserId="8547" LastEditDate="2015-07-13T14:23:54.530" LastActivityDate="2015-07-13T14:29:29.273" Title="How to calculate the wing chord of the aircraft Aero A.10?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="5" ClosedDate="2015-07-13T16:09:04.037" ContentLicense="CC BY-SA 3.0" />
  <row Id="16829" PostTypeId="2" ParentId="16828" CreationDate="2015-07-13T14:21:44.343" Score="0" Body="&lt;p&gt;Given the information in your question, it has to be assumed that the wing has a rectangular planform (because you mention no sweep angle and taper ratio). For a rectangular planform,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;span * chord = area&lt;/p&gt;&#xA;&lt;p&gt;chord = area/span = 11.78ft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-13T14:21:44.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16830" PostTypeId="2" ParentId="16828" CreationDate="2015-07-13T14:29:29.273" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;how to calculate [...] the wing chord?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Given the data you provided you can only compute the SMC (Standard Mean Chord), that is equal to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$SMC = \frac{S}{b}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $S$ is the wing surface and $b$ is the wingspan.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-07-13T14:29:29.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16831" PostTypeId="1" AcceptedAnswerId="27012" CreationDate="2015-07-13T14:38:42.530" Score="15" ViewCount="208" Body="&lt;p&gt;According to this &lt;a href=&quot;http://aviationweek.com/blog/c-17s-go-surfing-save-fuel&quot; rel=&quot;noreferrer&quot;&gt;Aviation Week article&lt;/a&gt; from October 2012, the US Air Force Research Laboratory ran a program called &lt;em&gt;Surfing Aircraft Vortices for Energy ($AVE)&lt;/em&gt; to test/prove that autopilot settings could be adjusted to allow &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot; rel=&quot;noreferrer&quot;&gt;C-17s&lt;/a&gt; to fly in formation using the wingtip vortices of the lead plane to reduce fuel consumption of the following planes. They seem to have found upwards of a 10% reduction in fuel for the following planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article indicated that previous experiments involved hand-flying of the aircraft in formation which required the equivalent concentration, focus and exhaustion levels of aerial refueling and was unfeasible for long duration flights, therefore the tests proposed to incorporate the formation flying into the autopilot&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know if these auto-pilot configurations have been put into use in line C-17s or other USAF transport aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="6979" LastEditDate="2016-01-30T17:13:07.067" LastActivityDate="2016-04-18T12:09:12.073" Title="Have the results of the USAF's $AVE program research been implemented?" Tags="&lt;autopilot&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16832" PostTypeId="1" AcceptedAnswerId="16835" CreationDate="2015-07-13T15:27:42.037" Score="26" ViewCount="8897" Body="&lt;p&gt;Why does the tower ask pilots what the reason is for a go-around? This seems to be standard for commercial flights.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-07-13T15:54:52.483" LastActivityDate="2015-07-14T15:54:58.210" Title="Why are pilots asked to provide a reason for a go-around?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;commercial-operations&gt;&lt;go-around&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16833" PostTypeId="2" ParentId="16832" CreationDate="2015-07-13T15:42:27.613" Score="40" Body="&lt;p&gt;The reason 1 pilot goes around may also be the reason the next pilot goes around, The second pilot would like to know before hand whether the runway is safe to land on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example if it is wind related he can delay landing until it dies down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is debris related then the tower can dispatch a cleaning crew.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-07-13T15:42:27.613" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16834" PostTypeId="2" ParentId="16832" CreationDate="2015-07-13T15:47:57.013" Score="10" Body="&lt;p&gt;Short answer: because first you're disrupting the traffic pattern (especially at larger airports that don't use a circular pattern and coordinate direct approaches instead) and the tower will want an explanation, and second because if there is a problem outside the cockpit causing you to execute the missed approach, other craft might have the same problem, and if the tower knows about it they can take steps to resolve it, or at least advise other incoming craft.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-13T18:48:15.433" LastActivityDate="2015-07-13T18:48:15.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16835" PostTypeId="2" ParentId="16832" CreationDate="2015-07-13T15:55:51.183" Score="32" Body="&lt;p&gt;Pilots are not required to give a reason for a go-around, just to say that they are going around. A go-around is a busy time for the pilot(s) of the aircraft - power, flaps, trim, must be set, gear raised in some cases. The pilot needs to aviate first. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower wants to know why the go-around was initiated by the pilot as it may be relevant for safety and/or operations. If the pilot is going around because of a botched approach then that won't impact other flights, however if there is a problem with the aircraft the tower can organize emergency resources. If the go-around is due to a situation on the ground then the tower can look to clear that up.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-07-13T15:55:51.183" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16836" PostTypeId="2" ParentId="16818" CreationDate="2015-07-13T16:16:17.647" Score="21" Body="&lt;p&gt;Zulu time, as others have pointed out, refers to UTC.  We use this time in aviation (and meteorology and surely others) because it is easier and it is standard.  It's the same time everywhere on earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying along the border between Arizona and New Mexico in the summer and given a hold:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cessna 1234 hold at FIX, right turns, 10 mile legs, expect further clearance at 1630, time now 1602&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If that were local time, you'd have to now determine if that fix is over AZ or NM, because NM observes daylight saving time and is in MDT/-0600 and AZ does not observe daylight saving time and is in MST/-0700.  This is a needless check that is distracting and can cause confusion all due to using a local time.  Instead, we know the times given are Z/UTC time and &quot;1630&quot; has an unambiguous meaning no matter where on earth our plane is located.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a similar situation when checking pre-flight weather.  Weather is reported in Z time and this makes it easy to calculate when you will get to your destination and what forecast is valid for that time.  If it were in local time you'd have to know additional information about time zones, which again could be a source of error and is needless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding to potential confusion are regions of earth that keep odd adjustments.  For example, St. Johns, NL, Canada is GMT-0330 in the winter and GMT-0230 in the summer.  There are even a few that are off by 15 minute adjustments (e.g. Nepal).  Combine this with knowing where DST is observed and where it isn't, and more importantly &lt;em&gt;when&lt;/em&gt; it is (USA DST has different start/end dates than other places) then it becomes very complicated to work in local time.  Working in universal time solves these problems.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="8282" LastEditDate="2017-07-29T12:14:23.150" LastActivityDate="2017-07-29T12:14:23.150" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16837" PostTypeId="2" ParentId="16832" CreationDate="2015-07-13T17:00:04.260" Score="14" Body="&lt;p&gt;The only reason for a go-around is that the pilot or ATC thinks that landing is not safe or possible for this approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the pilot does that, they follow the  &lt;strong&gt;5 Ups&lt;/strong&gt; memory aid (&lt;em&gt;Power Up, Nose Up, Gear Up, Flaps Up, Speak Up&lt;/em&gt;). You can see that by the time a pilot is &lt;em&gt;ready&lt;/em&gt; to inform ATC about go-around, he is already going around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commonly, when ATC requests a go-around, it is if there is an unsafe condition such as an aircraft, vehicle, or object on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the pilot decides to go-around, it can be one of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Go-around#Reasons_for_use&quot;&gt;following reasons&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the aircraft is not lined up&lt;/li&gt;&#xA;&lt;li&gt;it is not configured properly for a safe landing&lt;/li&gt;&#xA;&lt;li&gt;an aircraft, vehicle or other object has not cleared the runway&lt;/li&gt;&#xA;&lt;li&gt;no landing clearance was received (at a towered field)&lt;/li&gt;&#xA;&lt;li&gt;the landing gear is not properly extended&lt;/li&gt;&#xA;&lt;li&gt;a dangerous meteorological condition is experienced on final approach (e.g., poor visibility, excessive cross-winds, windshear, etc.)&lt;/li&gt;&#xA;&lt;li&gt;excessive energy (too high or too fast)&lt;/li&gt;&#xA;&lt;li&gt;or any other unsafe condition is detected&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-07-13T17:00:04.260" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16838" PostTypeId="1" CreationDate="2015-07-13T17:17:25.657" Score="8" ViewCount="3274" Body="&lt;p&gt;I've seen many references here to a flight going around, and YouTube is filled with videos of it happening, but I don't recall ever having been on a commercial flight that had an aborted landing. It might have happened when I flew as a small child, but, having been really, &lt;em&gt;really&lt;/em&gt; excited to fly, I think I'd have remembered that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How often do commercial flights actually abort a landing and have to make another attempt?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm primarily curious about US statistics, but non-US would be interesting as well.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-07-13T19:07:13.423" LastActivityDate="2015-07-13T19:07:13.423" Title="How often do commercial flights go-around?" Tags="&lt;landing&gt;&lt;go-around&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-07-13T19:00:01.790" ContentLicense="CC BY-SA 3.0" />
  <row Id="16839" PostTypeId="2" ParentId="16838" CreationDate="2015-07-13T17:23:23.590" Score="8" Body="&lt;p&gt;As &lt;a href=&quot;https://en.wikipedia.org/wiki/Go-around#Safety&quot; rel=&quot;noreferrer&quot;&gt;mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Go-arounds occur with an average rate of 1–3 per 1000 approaches.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most of the videos on YouTube are of go-arounds because of weather. This is not a common scenario as many flights divert to other airports where weather is less severe.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-07-13T17:23:23.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16840" PostTypeId="2" ParentId="16777" CreationDate="2015-07-13T18:05:43.940" Score="18" Body="&lt;p&gt;This is some speculation, but one potential reason is that U.S. carriers already have fleets of Embraer and Bombardier jets in this basic size (the Su-100 competes directly with the Embraer 190/195 and Bombardier's larger CRJs and upcoming C-series). The companies making these jets are located in pretty firmly U.S.-allied countries that are unlikely to see any economic restrictions that might hamper the ability of U.S. regional carriers to procure new airframes or parts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same cannot be said for Russia, which from 1946 until 1991 was pretty much embargoed by NATO signatories, and the relationship between Russia and the West since then has been testy. While the U.S. currently does not have a trade embargo with Russian civilian jet production operations (current sanctions attempt to specifically target military R&amp;amp;D and direct investment), that can change in a heartbeat if Russia continues to throw its weight around in neighboring countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the seating capacity of this jet is a bit of an odd duck, as it blurs the line between the needs of regional vs. national U.S. carriers. The basic problem is that regionals, by their very nature, operate out of smaller cities with fewer potential passengers, at distances from major hubs that makes driving to that larger airport and flying from there more palatable for passengers. These considerations cause passenger count on regionals to drop off dramatically compared to longer &quot;national&quot; routes. The largest thing American Eagle currently flies is a Bombardier CRJ-900 (75 passengers in 2-class config), with the most commonly operated jet in AE's fleet being the Embraer ERJ145 (50 seats all-economy). By comparison the smallest plane operated under the full American badge is the A319 (124 seats in 2-class config). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's an obvious gap between the two subsidiaries' aircraft capacities, but not much interest (by American at least) in filling it with a 100-seat jet like the SSJ100 (or E195 or C100). The primary reason is the collective bargaining agreements that pilots have with the airlines; they include, among other things, a requirement segregating the aircraft used by regional versus national subsidiaries. If you want to fly a plane with more than 80-100 seats (depending on exact terms of the agreement) on the route, you're paying a national airline flight crew the extra bucks to fly it; it's a violation of the CBA to put a 737 or A319 in the hands of a regional airline pilot because that takes the job away from the more senior pilots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A secondary reason is that U.S. domestic airlines like American tend to favor more, smaller flights over fewer larger ones. This allows the airline to &quot;rightsize&quot; the route schedule (and its fleet) to passenger demand more closely and with fewer disruptions. If on a given day of the week, 200 passengers need to get between a regional airport and a larger hub, the airline could do that with four 50-place jets, or 3 75-place jets, or two 100-place jets. Theoretically, if demand were constant, it could save money the fewer flights it made, as the cost of the 50-seat Embraer's two-man flight crew would be roughly the same as the Sukhoi's, but with the Sukhoi you spread that cost over twice the passengers so your gross margin is higher. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, an empty seat is a big fat goose-egg on the revenue for that seat for the flight, so if passenger demand varies (and it does, from day to day and seasonally), running larger jets either forces you to turn away some customers that you can't fit into the reduced schedule, or add flights that run mostly empty. Neither of these are palatable options for the airline; one pushes potential customers into the arms of their competitors, while the other has you running at least one flight that day costing tens of thousands of dollars for a handful of people with tickets whose regional component of the price might not even cover the pilot's salary for the duration of the flight (regionals are often &quot;connecting&quot; flights; DFW to PHX costs about \$320, ACT to DFW about \$300, but ACT to PHX via DFW only costs about \$360, so depending on how you part it out, the ACT-DFW leg of ACT-PHX might only really make you \$40 a seat, which might not break even if the plane's full, much less if it's half empty).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, assuming any plane an airline would buy or lease is profitable when it's fully loaded with paying customers, American is more likely to successfully operate a route, and its entire network, using more smaller planes and scheduling a different number of interchangeable airframes and flight crews each day to maximize utilization, than it would be trying to also minimize the number of flights by using a variety of airframe sizes, which involves ensuring those airframes and the flight crews to run them are all in the right places at the right times (and deadheading - flying an empty plane from where it is right now to where it will be needed later - is bad no matter what the plane size, but typically more palatable with a smaller jet that has lower total operating costs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, American isn't the only carrier with a regional subsidiary. US Airways Express and JetBlue, as well as several other New World regional carriers outside the U.S., regularly operate 100-seat Bombardier and Embraer airframes on regional connectors, and it would stand to reason that Sukhoi could get a piece of that action. It could also &quot;stretch&quot; the Superjet and try to compete in the national domestic market with the 125-seat A319 and 737-700 which are becoming more and more popular as U.S. domestic flights get &quot;rightsized&quot;. However, the delicate nature of Russian-Western relations will probably continue to make Sukhoi a risky proposition for U.S. carriers that need a reliable source of airframes and parts on a 20-25 year timeline.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-11-04T18:42:54.813" LastActivityDate="2015-11-04T18:42:54.813" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16841" PostTypeId="1" AcceptedAnswerId="16842" CreationDate="2015-07-13T18:38:43.130" Score="20" ViewCount="5774" Body="&lt;p&gt;Given the graph in &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;this answer&lt;/a&gt;, the temperature are quite high inside a jet-engine, even greater that many &lt;a href=&quot;http://www.wolframalpha.com/input/?i=metal+melting+point&quot; rel=&quot;nofollow noreferrer&quot;&gt;metal's melting point&lt;/a&gt;. I understand &lt;a href=&quot;https://aviation.stackexchange.com/questions/11969/what-prevent-jet-engines-design-with-bigger-by-pass-ratio/11972#11972&quot;&gt;high core temperature are efficient&lt;/a&gt;.  A jet engine is designed to work for several hours at those high temperature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, starting the engine (i.e. going from ambient temperature everywhere inside the engine to more than 1500°C in the combustion chamber while not significantly changing the temperature at the first low pressure compression stage) may be quite &lt;a href=&quot;http://www.wolframalpha.com/input/?i=metallic+element+thermal+expansion&quot; rel=&quot;nofollow noreferrer&quot;&gt;stressful for material&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is in two parts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How is the high temperature handled, especially in the combustion chamber and the high pressure turbine? I read somewhere that the turbine can be cooled by air flowing inside the blades but I cannot find the reference. I also wonder where this cooling air comes from.&lt;/li&gt;&#xA;&lt;li&gt;How is the stress on material due to temperature changes (between full thrust and shut down, and maybe when changing thrust in mid-flight) handled?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-13T19:33:56.327" Title="How are temperature differences handled in a jet engine?" Tags="&lt;jet-engine&gt;&lt;temperature&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16842" PostTypeId="2" ParentId="16841" CreationDate="2015-07-13T19:16:40.633" Score="19" Body="&lt;p&gt;&lt;strong&gt;1. The combustion chamber&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature here is usually controlled via design of the chamber shape, in particular of the location where combustion occurs vs the airflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/JeR9P.jpg&quot; alt=&quot;Detail of combustion section&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;http://www.buran-energia.com/mriya-antonov/mriya-moteur-engine-desc.php&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the image above you can see that the fuel line (2) terminates in a nozzle. The nozzle will turn the fuel into tiny droplets to increase the surface area and hasten the combustion process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indicated with (6) are instead the main air holes: the cool air coming from the compressor (on the left side) enters the chamber with high pressure from these holes. Note that the holes are distributed in an annular pattern: high pressure air will be entering from all sides of the chamber.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The result is that the flame will not directly touch the walls of the&#xA;chamber, we then got rid of &lt;strong&gt;conductive&lt;/strong&gt; heat transmission.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Convective&lt;/strong&gt; is a non-issue: cool air keeps coming and hot air goes&#xA;into the turbine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Radiative&lt;/strong&gt; heat transmission might be an issue, but the new air&#xA;incoming will cool the walls via conduction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The engine can thus run without the combustion chamber melting. Note that the use of specific materials does greatly improve the conditions, as higher temperatures can be tolerated, and thus better efficiencies achieved.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. The turbine cooling air&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air is usually bled from a stage of the compressor, usually a high pressure stage, in a similar manner as done for the air used for the passenger compartment.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. Thermal stresses&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;a. Short term&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the duration of a flight the blades will warm up when the engine is turned on and cool down at the end of the flight. Intermediate load variation do not have a significant impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the initial warming and the final cooling do not pose a significant problem. The only effect to be taken into account is that the rotating hot blades will become slightly longer: a special material is placed on the opposing stationary side so that the gap is minimal during operation and the losses due to the air going around the blades (instead of between them) are reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;b. Prolonged&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most problematic aspect here is the so called &quot;creep&quot;: the blades, after prolonged use, will tend to change shape, because they tend to be more malleable at high temperatures, exactly when they are under high tensile load. This becomes a problem over the lifetime of an engine, not during a single flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To mitigate this problem the blades are nowadays manufactured as single crystals: each blade is a single solid block of metal and not made up af many tiny crystals as the metal tools we use everyday. This is because under tensile load each of the crystals can slide over its neighbors (and high temperatures facilitate this) changing the shape of the blade. To visualize it, think of a rubber band that does not go back to its original form.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having a single crystal prevents this sliding, giving more strength to the blade.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1696" LastEditDate="2015-07-13T19:33:56.327" LastActivityDate="2015-07-13T19:33:56.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16843" PostTypeId="2" ParentId="16816" CreationDate="2015-07-13T20:20:08.287" Score="10" Body="&lt;p&gt;The short of it is that most such ex-military aircraft, and replicas built new to spec on these designs, do not have a &quot;type&quot; as defined by the FAA at all. Because the absence of a type means the aircraft can't be certified as airworthy in the normal way, and pilots of these aircraft cannot receive a type rating to fly them, the certification of aircraft and pilot is a bit different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft must first be issued an FAA &quot;Special Airworthiness Certificate&quot;. This is essentially a slightly more rigorous form of airworthiness inspections for type-rated aircraft and virtually identical to that for experimental and/or home-built aircraft, resulting in the certification of the craft as airworthy in general even though it does not fall into a predefined aircraft type for which FAA instructors can issue type ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airman, because he can't be certified to fly a non-existent FAA aircraft type, must receive a special rating certification called a &quot;Letter of Authorization&quot;, allowing the pilot to fly aircraft of a specific model, and/or a &quot;set&quot; of aircraft that have similar configuration, power, weight and other operational specifications and limits (but that aren't similar or common enough for a type rating). The training required for an LOA includes a combination of ground school and flight school containing information and in-flight training on the specific model to be authorized. But, when it is not possible or practical to do in-flight training in the exact model of aircraft to be authorized (usually because the aircraft in question is a single-seater with no two-seat configuration available), flight training in a &quot;similar&quot; aircraft can be a substitute. Pilots of vintage single-seat warplanes like P-51s typically get their flight training for the category in something similar to what military pilots of the day would have used, such as an AT-6. If the flight school just happens to have a Twin Mustang laying around, that would be even better, and also more directly applicable to multi-engine warbirds like the P-38.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to your example, say you get your hands on a &quot;de-fanged&quot; A-10 (which would require a ton of ballast weight to be added, literally; the GAU-8 weighs about as much as a Cadillac, but I digress). All flying examples are single-seaters; however, the avionics, especially of the original A-10A without the glass cockpit upgrade of the PEUP program, are comparable to any 70's-era jet trainer. So, you could receive flight training in a T-33, which is a trainer-compatible straight-wing turbojet with more similarities in its flight characteristics to the A-10 than differences. Coupled with ground instruction and/or simulator time on the specific systems of the A-10 (Which won't include any weapons integration, but honestly for the A-10A that was a single FLIR display and the arming/firing switches, and the C variant only upgraded that to a pair of MFDs; other than relative positioning, the flight instruments of the A-10 would be familiar to any PPL), you could be certified to fly your A-10 solo without any flight hours in an A-10 specifically. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same might apply to aircraft that do have two-seater variants but where the flight school is unable to procure one. If you won the Powerball, and put a chunk of that money into your very own milsurp F-15C (\$38 million a pop back when they were being made and that's in late 1970s dollars), it's highly unlikely your local flight school would be willing to pony up for an F-15D two-seat configuration to train you on it (unless you bought the plane for them with another big chunk of your lottery winnings). They might, however, have a T-38 in their inventory or be able to loan one from the nearby naval air station, which would give you a primer into the capabilities of a multi-engine turbofan ex-military fighter. Honestly, though, if you wanted to fly an F-15, you'll probably want a two-seater, and your CPL, so you could give rides to paying customers and offset the cost of running this beast (typical fuel load without droptanks, 13,500 lbs which is about 1,985 gallons. With Jet A running about \$4.85/gallon, the cost of a fillup would be somewhere in the $10,000 neighborhood which would give you a cruising range of about 1,000 miles, so you could offer this as a special type of jet taxi).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's some more reading on the subject: &lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v05%20airman%20cert/chapter%2009/05_009_002rev1.htm&quot; rel=&quot;nofollow&quot;&gt;FAA Flight Systems Information Management System - 8900.1 V5 Chapter 9 Sec 2 - Airman Qualification Requirements for Aircraft for Which the Operating Limitations Require an FAA‑issued Authorization to Act as Pilot in Command&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T20:54:28.943" LastActivityDate="2015-07-23T20:54:28.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16844" PostTypeId="1" CreationDate="2015-07-13T21:01:17.563" Score="6" ViewCount="1112" Body="&lt;p&gt;I have a privacy preserving technology that could conceivably help prevent the Germanwings &lt;a href=&quot;http://www.slate.com/blogs/the_slatest/2015/03/25/germanwings_pilot_reportedly_locked_out_of_cockpit_before_crash.html&quot; rel=&quot;noreferrer&quot;&gt;crash of 2014&lt;/a&gt;.  The idea would be there is a long list of issues that would prohibit a pilot from flying encoded on a ID card that anonymizes a pilot's information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that a list might look like this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Overwork (no sleep)&lt;/li&gt;&#xA;&lt;li&gt;Simulator experience, test results&lt;/li&gt;&#xA;&lt;li&gt;Medical issues (temporary)&lt;/li&gt;&#xA;&lt;li&gt;Drug tests&lt;/li&gt;&#xA;&lt;li&gt;Psychological issues&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A list of medical providers would link the results together, anonymously, and during the pre-flight check, the ID card would be scanned and rather than a specific issue being highlighted, (depression), the pilot would be asked to rest for a while.  No system would know why the rejection occurred, except for the pilot himself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might for a balance of privacy, safety, and accountability without compromising need to know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, I would appreciate any official, or carrier specific list of reasons a pilot would be rejected from flying.  The closest I've gotten to learning about this is MSFT Flight Simulator and a few hours in a Cessna &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supplemental information would be helpful as well (your thoughts about this solution)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Scope&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per the comments below this question, the scope is limited to US&lt;/p&gt;&#xA;" OwnerUserId="9352" LastEditorUserId="9352" LastEditDate="2015-07-13T21:41:28.010" LastActivityDate="2016-01-08T23:55:29.043" Title="How do I locate a list of restrictions that would prevent a pilot from flying in the US?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;commercial-aviation&gt;&lt;medical&gt;&lt;caa-uk-regulations&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16845" PostTypeId="2" ParentId="16844" CreationDate="2015-07-13T21:42:30.837" Score="8" Body="&lt;p&gt;The list is exactly one item long:&lt;br&gt;&#xA;&lt;strong&gt;Any condition which would impair your ability to conduct the flight safely, and in accordance with FAA Regulations.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any more specific list will miss things and be riddled with loopholes - at some point we have to trust that pilots are sane and responsible individuals, just like we do when we let people get in a car.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;From a medical perspective &lt;a href=&quot;http://www.faa.gov/licenses_certificates/medical_certification/&quot;&gt;the general medical certification information page&lt;/a&gt; at faa.gov is a good starting point, and &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/&quot;&gt;the FAA's guidance for Aviation Medical Examiners&lt;/a&gt; has lots of details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also &lt;a href=&quot;https://www.faa.gov/licenses_certificates/medical_certification/faq/response6/&quot;&gt;some disqualifying conditions which are explicitly listed in the regulations&lt;/a&gt;, and &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/pharm/dni_dnf/&quot;&gt;a list of (some of the) medications which will prevent the FAA from issuing a medical certificate&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The things I noted above will prevent you from getting a medical certificate.  Once you HAVE that certificate &lt;a href=&quot;https://www.leftseat.com/imsafe.htm&quot;&gt;the &quot;I'M SAFE&quot; checklist&lt;/a&gt; or something equivalent expands upon that and tries to help pilots determine whether they're fit to fly &lt;em&gt;right at this moment&lt;/em&gt;. There are various ways of interpreting the acronym, but a common one is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I&lt;/strong&gt; for Illness&lt;br&gt;&#xA;Do I have an illness or any symptoms of an illness?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;M&lt;/strong&gt; for Medication&lt;br&gt;&#xA;Have I been taking prescription or over-the-counter drugs?&lt;br&gt;&#xA;If so, do they have a negative affect on my ability to perform this flight?&lt;br&gt;&#xA;Are any of them disallowed by the FAA? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;S&lt;/strong&gt; for Stress&lt;br&gt;&#xA;Am I under psychological pressure from the job or personal issues?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; for Alcohol&lt;br&gt;&#xA;Have I been drinking within eight hours? Within 24 hours?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;F&lt;/strong&gt; for Fatigue&lt;br&gt;&#xA;Am I tired and not adequately rested?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;E&lt;/strong&gt; for Eating&lt;br&gt;&#xA;Am I adequately nourished, or at least &quot;not hungry&quot;?&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-13T21:42:30.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16846" PostTypeId="2" ParentId="16844" CreationDate="2015-07-13T22:06:31.247" Score="6" Body="&lt;p&gt;There are four very general reasons - really, categories of reasons - that I can think of to ground a pilot (or for a pilot to ground himself):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It would be illegal to fly for obvious procedural reasons, e.g. your license has expired, you've exceeded legal limits on flying hours&lt;/li&gt;&#xA;&lt;li&gt;It would be illegal to fly for obvious medical reasons, e.g. you're taking a medication that the FAA doesn't allow&lt;/li&gt;&#xA;&lt;li&gt;You're &lt;em&gt;legal&lt;/em&gt; to fly, but your employer's &lt;em&gt;policies&lt;/em&gt; don't allow you to fly, e.g. you haven't had some specific internal sign-off required for a certain aircraft, route or crew combination&lt;/li&gt;&#xA;&lt;li&gt;You shouldn't fly for non-obvious reasons that are known only to yourself, e.g. you're suffering from stress or grief, or have an undisclosed medical condition&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But the thing is, airlines already track as much of this information as possible anyway. If they didn't track them, they couldn't schedule pilots on flights efficiently and they have to make sure that every pilot is up to date with medicals, licenses etc. to avoid scheduling problems and lost revenue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the only real issue is when a pilot knows he &lt;em&gt;should&lt;/em&gt; ground himself but chooses not to. There's no solution to that except to encourage pilots to identify those situations properly, and to have laws and policies that don't penalize pilots who self-ground for good reasons. Even if Germany - or any other country - starts allowing doctors to share private medical data with aviation regulators and airlines, it won't prevent cases where pilots deliberately conceal medical issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And you also have to consider that airlines would quickly become very unhappy with any system that says &quot;this pilot can't fly today but we can't tell you why and we can't tell you when he will be able to fly again&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So - at least in my opinion - your proposal mostly reproduces what airlines are already doing, and creates an additional problem of unpredictable staffing. Considering how rare accidents are, it's doubtful if any 'solution' is actually necessary, although I do think it's great that someone is thinking about how to balance privacy with safety.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-13T22:06:31.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16847" PostTypeId="1" AcceptedAnswerId="16863" CreationDate="2015-07-13T22:41:05.867" Score="46" ViewCount="13679" Body="&lt;p&gt;On a recent airline flight, I noticed that the spacing of the plane's windows was different from that of the passenger seats: some of the rows had a window directly in line with them but for others, the windows were partially obscured by the seatbacks in front or behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason that the windows aren't manufactured with a regular spacing to align with the seat rows? Does it have to do with the fact that different airlines may be using different seating configurations for the same model of aircraft?&lt;/p&gt;&#xA;" OwnerUserId="9348" LastEditorUserId="1696" LastEditDate="2015-10-07T14:33:47.200" LastActivityDate="2017-09-14T18:28:55.493" Title="Why aren't airliner windows aligned with their seats?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16848" PostTypeId="2" ParentId="16847" CreationDate="2015-07-13T22:54:22.013" Score="22" Body="&lt;p&gt;Because airliners skimp on spacing and steal your leg room to squeeze in another row of seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why not design the plane with the eventual seat spacing in mind? Airliners can decide their own spacing so there would always be planes where they won't match up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also there has to be a certain amount of hull to keep the strength needed for the fuselage to work as it needs to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the designers need to make a compromise on number of seats and strength of the hull.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-07-13T22:54:22.013" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16849" PostTypeId="1" CreationDate="2015-07-13T23:26:13.583" Score="2" ViewCount="2071" Body="&lt;p&gt;Hello I am thinking about buying a Sonex to start to learn how to fly. I want to know, if it is a good plane to learn in?&lt;/p&gt;&#xA;" OwnerUserId="9354" LastEditorUserId="8482" LastEditDate="2015-07-14T04:53:38.193" LastActivityDate="2015-07-23T15:26:44.447" Title="Is Sonex a good trainer plane?" Tags="&lt;aircraft-design&gt;&lt;flight-training&gt;&lt;student-pilot&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-07-14T07:53:16.880" ContentLicense="CC BY-SA 3.0" />
  <row Id="16850" PostTypeId="2" ParentId="2186" CreationDate="2015-07-13T23:30:51.283" Score="4" Body="&lt;p&gt;To add a voice to the choir...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are only two models of commercial airliner still in service anywhere that have an exit that would allow passengers to jump relatively safely; jumpers from practically any modern plane, like this 737NG, would face potentially fatal encounters with the engines, wings or tail surfaces attempting to exit from the sides of the aircraft in flight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/3dglk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those two aircraft are the MD-80 and the Boeing 727, which have a ventral airstair designed for use at airports without ground services like mobile ramps or jetways:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aOMSj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most other large T-tails had ventral airstairs, but these two aircraft are the only ones left in service with any major U.S. commercial operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 727 in fact was specifically chosen for a 2012 &quot;crash test&quot; of a commercial airliner, because it allowed the crew that flew it to the crash site to bail out the back ala &lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper&quot; rel=&quot;nofollow noreferrer&quot;&gt;D.B. Cooper&lt;/a&gt;, leaving the aircraft under remote control from a chase plane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8SlMB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This experiment still doesn't reflect any real-world possibility for a fully-loaded plane to bail out prior to a crash, for the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 727 is no longer in service with any U.S. passenger airline (a few cargo carriers like DHL still have some serviceable 727 airframes), and American, the last major operator of the MD-80, is retiring the last airframes in the next couple of years, replacing them with B737s and A319s. If this retirement goes to schedule, there will be no airframes with ventral stairs in operation by any U.S. passenger line by 2018.&lt;/li&gt;&#xA;&lt;li&gt;The rear airstair on &quot;Big Flo&quot; was heavily modified, all but removed actually, so that it would have negligible effect on the aircraft's aerodynamics when open (the airstair is not meant to be opened during flight, and in fact a wind-actuated lock called the &quot;Cooper Vane&quot; normally keeps the airstair from being opened when the aircraft is travelling at speed, a direct result of the D.B. Cooper hijacking).&lt;/li&gt;&#xA;&lt;li&gt;The plane was on a stable wings-level descent at 130 knots, nowhere near cruising speed and slow even for approach speed.&lt;/li&gt;&#xA;&lt;li&gt;A total of 6 people had to bail out of Big Flo, not the 100-plus people that would have to hit the silk in a fully loaded passenger flight.&lt;/li&gt;&#xA;&lt;li&gt;Everyone on the plane knew it was going to crash &lt;em&gt;years&lt;/em&gt; before they took off. If passengers had &lt;em&gt;that&lt;/em&gt; kind of advance notice their flight would end that way, they wouldn't even get on.&lt;/li&gt;&#xA;&lt;li&gt;Everyone on board was prepped and ready for their jump 30 seconds before egressing. Even giving that same time to every row of a fully-loaded jet instead of every 2 or 3 people, it would take a full 14 minutes to get everyone out of a fully-loaded 727. If you have that kind of time to orchestrate a bail-out, you don't need to.&lt;/li&gt;&#xA;&lt;li&gt;Everyone wearing a parachute knew what they were doing. The copilot and flight engineer bailed in tandem jumps with master skydivers; the pilot and cameraman had their own skydiving certs and made solo jumps.&lt;/li&gt;&#xA;&lt;li&gt;Everyone on board the plane was dressed for the occasion in flight suits that facilitated skydiving, with the actual skydivers wearing their chutes the whole time. No dresses or other baggy street clothes, and the only in-flight prep for the tandem jumpers was to hook the two harnesses together.&lt;/li&gt;&#xA;&lt;li&gt;Other than the modified airstair and the fact it was past its rated number of pressurization cycles, there was nothing mechanically wrong with the aircraft (until it hit the ground of course).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, in other words, nothing about the way the crew exited this aircraft prior to the crash would apply to your average passenger airliner. You might think bailing out of an aircraft gives you a chance, but if you don't know what you're doing with a parachute on your back, you'll be just as dead outside the plane as in. Considering that the most generous estimates say that only one in 20 people even do a tandem skydiving jump once in their lives, the percentage of people on board your average airliner who'd be likely to negotiate their way back to the ground with a parachute is a rounding error.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-28T14:51:21.673" LastActivityDate="2015-10-28T14:51:21.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16851" PostTypeId="2" ParentId="3432" CreationDate="2015-07-14T00:46:36.933" Score="4" Body="&lt;p&gt;The Cessna 150/152 is considered a good trainer aircraft for a combination of desirable qualities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Low cost&lt;/strong&gt; - An older 150 airframe is comparable in price to a car (between \$25k and \$50k usually depending on internal instrumentation), making the loan payments a little easier than that Gulfstream.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Mechanical simplicity&lt;/strong&gt; - One engine with fixed-pitch prop, fixed landing gear, cable control linkages, manual everything. This gives three main advantages:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less to break. When things break on an airplane, you can't just pull off to the side of the road and call a tow truck. So, the simpler the system, the less that can go wrong.&lt;/li&gt;&#xA;&lt;li&gt;Less to have to learn. More complex aircraft increase the pilot's workload for standard procedures such as approach and landing (and variations like the missed approach/go-around). Retractable gear and variable prop pitch, plus flaps, define a &quot;complex&quot; aircraft in FAA regs requiring a special endorsement.&lt;/li&gt;&#xA;&lt;li&gt;Less to inspect and maintain. Preparing to fly an aircraft always incorporates a preflight &quot;360&quot; walk around the aircraft checking control surfaces, intakes and engine compartments, lights, external components of instruments like the pitot tube and stall horn, etc, followed by an internal check of systems like the radios, control linkages, flight instrument displays etc. This takes more time the more systems you have on board to check. Those same systems also have to be inspected more thoroughly for the annual mechanical certification (a more in-depth counterpart to a car's safety inspection) which will increase the &quot;total ownership cost&quot; of a more complex airframe. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Docile handling&lt;/strong&gt; - The 150 is nicknamed the &quot;Land-o-matic&quot; for its reputation for being an extremely forgiving, easy-to-fly aircraft. Cessnas in general tend to handle very well for &quot;everyday&quot; flying because of their high-wing design; this generally makes them less susceptible to entering fatal upsets like the spiral dive (they can still spin-stall on you).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Full instrumentation available&lt;/strong&gt; - If you want your instrument rating, you need access to a plane that will allow you to practice IFR, and that includes the full set of IFR navigation instruments. The 150/152's instrument panel, while small and simple (like the rest of the aircraft), is fully decked out for radionavigation, and a GPS unit is typically pretty simple to add.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2018-11-12T22:28:28.247" LastActivityDate="2018-11-12T22:28:28.247" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="16852" PostTypeId="1" AcceptedAnswerId="16873" CreationDate="2015-07-14T00:57:44.357" Score="13" ViewCount="1509" Body="&lt;p&gt;I notice, looking at pictures of various light singles, that the tail number of the aircraft is typically prominently displayed somewhere towards the top of the instrument panel. If it were your own plane, you would quickly memorize it given the dozens of times per flight you have to give your callsign, but it's still useful for new pilots, rentals and trainers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That led me to wonder: are the tail numbers of commercial aircrafts also posted in the cockpit, or is it omitted because commercial airliners more often use their company and flight number as their callsign, while the equipment used for a flight can change every time? I don't see any registration number label in &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6e/Cockpit_of_737-300_LN-KKU.jpg&quot; rel=&quot;noreferrer&quot;&gt;this shot of a 737 cockpit&lt;/a&gt;, for instance, but it could be on the overhead panel obscured in this shot.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8547" LastEditDate="2015-07-14T14:44:58.567" LastActivityDate="2015-07-14T14:44:58.567" Title="Do commercial airliners have the tail number placed somewhere on a placard in the cockpit?" Tags="&lt;commercial-aviation&gt;&lt;cockpit&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16853" PostTypeId="2" ParentId="16852" CreationDate="2015-07-14T01:51:56.097" Score="10" Body="&lt;p&gt;Yes, on a commercial airliner typically the tail number and the SELCAL (if so equipped) are placarded on the panel.  It's hard to find sometimes in picture because it may be behind the yoke, but it should be there somewhere.&lt;/p&gt;&#xA;" OwnerUserId="162" LastActivityDate="2015-07-14T01:51:56.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16854" PostTypeId="2" ParentId="16849" CreationDate="2015-07-14T02:13:51.993" Score="8" Body="&lt;p&gt;I would avoid the Sonex, or any other kit aircraft, until you have some student flight time under your belt and are sure that's the way you want to go.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problems with using a kit LSA to learn include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The &quot;Build then fly&quot; process of a kit without a license assumes you will want to do the latter after doing the former.&lt;/strong&gt; Plenty of novice pilots spend 5 to 10 hours at the yoke and either get it out of their system and lose interest, or wash out in other ways (fail medical, can't pass written tests or checkrides and give up, run out of money to spend on rentals and fuel). If that happens to you, you'll be stuck with a kit you bought new, which you can't fly and now have to sell used. It's better to rent your way through the first few weekends as a student, then once you have your student cert, a few flight hours, solo endorsement and you're sure you are able and want to keep going toward a sport or private cert, you can look for an aircraft to own and practice with.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Building a kit means getting that kit certified airworthy.&lt;/strong&gt; An amateur-built plane has to go through a rigorous mechanical inspection before you'll be allowed to take it up in the air. The fact that it's a kit for an aircraft fitting the &quot;light sport&quot; type rating might make it a little easier, but they might treat it as an &quot;experimental&quot; craft just because it's a homebuilt and go through the &quot;Special Airworthiness Certification&quot; process for those types of planes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Buying someone else's kit means inheriting their mistakes.&lt;/strong&gt; If you don't build, and instead buy a kit plane that someone else went through the trouble of building and getting certified, you're still flying a homebuilt. Anything the FAA inspector missed could cause a failure in flight, and you can't just pull over and call a tow truck when that happens. The same could be said of your own homebuilt, and overall with the strict mechanical inspection criteria of planes this isn't as big a problem buying a plane versus buying a used car, but it's something to think about; they built and configured it their way, and if that's not &quot;your&quot; way or even the &quot;usual&quot; way it can be distracting in flight, and distracting is dangerous.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The Light Sport class is designed for day VFR with a limited range.&lt;/strong&gt; If all you want is a sport pilot certificate to go out flying in fair weather near your home airstrip, great, grab an LSA like the Sonex and have fun. If you want to progress to a PPL, and fly cross-country, at night or in IMC with your instrument rating, you'll need a plane capable of flying in such conditions for your checkride and other training time including at least one serious cross-country flight. The stock Sonex builds I'm looking at now do not have the IFR &quot;big 6&quot; and really no room to mount them. You can go glass, but instrumentation's only one piece of the puzzle; you'd also need an external light kit which doesn't come stock, and the airframe has to be rated for flight in minimum winds as well as IMC like rain, which most LSAs simply are not designed for.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;LSAs have limited power by design.&lt;/strong&gt; That doesn't mean other aircraft don't have similar power ratings (the stock Cessna 150 is only 100hp while there's an engine kit for the Sonex providing 120), but the Sport Pilot license was designed for flying LSAs with a max power of 87hp, with an instructor endorsement required to fly anything more powerful. Just one more hurdle to getting rated to fly your own up-engined Sonex (or anything else besides).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Just my analysis. Again, if you just want to start with a SPL (20 hours flight time, some ground instruction and a written test, no medical beyond the basics for a driver license) and see where it goes from there, then a Sonex kit, base price about 18 grand, is a pretty good deal assuming you're good with tools. But if you want to progress to where flying is useful beyond simple recreation, you'll start rubbing up against the limitations of an LSA sooner than you would in a more full-featured trainer. That more full-featured trainer is also going to be more expensive, but it'll be a plane you can use much further into your flying career, and if you take care of it, will hold cash value and even match inflation so you can use it as a store of value to trade up (the 150's original retail price back in the 60s was around \$7500; those same '60s airframes change hands at around \$25,000 now).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T15:26:44.447" LastActivityDate="2015-07-23T15:26:44.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16855" PostTypeId="1" AcceptedAnswerId="16858" CreationDate="2015-07-14T02:18:12.140" Score="16" ViewCount="4463" Body="&lt;p&gt;My favorite features of the United Airlines app are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you are able to see what specific aircraft will be operating your flight&lt;/li&gt;&#xA;&lt;li&gt;you are able to trace that aircraft back indefinitely via the &quot;Where is this aircraft coming from?&quot; button&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I noticed that each aircraft has a specific number aside from the aircraft model (e.g Boeing 737-900 #3815), that references which specific aircraft will be operating your flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is how far ahead does an airline plan which &lt;strong&gt;&lt;em&gt;specific&lt;/em&gt;&lt;/strong&gt; aircraft will be operating a flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not asking if the airline knows that a B737 model will be operating a flight, but I'm asking more specifically how far ahead do they know which specific aircraft in the fleet will be operating a particular flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;This question may be broad as I realize that it may differ between airlines. I'm just curious as I like to see where my flights have been and will go, I find this very interesting.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="7373" LastEditorUserId="8547" LastEditDate="2015-07-14T14:43:29.070" LastActivityDate="2015-07-27T22:51:18.153" Title="How far ahead does an airline know which aircraft you will be flying on?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;dispatch&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16856" PostTypeId="2" ParentId="16847" CreationDate="2015-07-14T02:23:42.933" Score="15" Body="&lt;p&gt;An aircraft is delivered in a very basic configuration; no seats, and windows running the entire length of the aircraft. The airline is then tasked with choosing and installing their specific makes of not only seats, but also galleys and sometimes lavatories. All of these must fit into that initial basic aircraft, meaning that this layout may not perfectly fit into the &quot;mold&quot; of the original aircraft. This means that there could be some misalignments because the seats could be of different spacing or size than the windows were originally designed for. This system of configuration is better for both the aircraft manufacturer (because it is cheaper to build one basic airframe as opposed to hundreds of slightly tweaked ones) and the airline (because they are able to customize the interior to their liking).&lt;/p&gt;&#xA;" OwnerUserId="7373" LastActivityDate="2015-07-14T02:23:42.933" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16857" PostTypeId="2" ParentId="2873" CreationDate="2015-07-14T02:55:30.270" Score="6" Body="&lt;p&gt;The design philosophy is: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Keep the operation of each control or indicator as reliable as possible and as simple to use as possible. That there are so many controls and displays in some cockpits is a reflection of the number of things that need to be controlled or monitored. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Put the most important things in the most prominent location for easy reach or reference. For some things, it means duplication for both pilot and co-pilot, increasing the total number of items.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If it's safety-critical, make sure it has a back-up. That can further increase the number of controls and displays.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;What to the layperson looks like a jumble actually has logic. When you understand the logic and purpose of the various controls and displays, you will find that there are groupings and standard positionings for certain items. For example: aircraft with side-by-side seating always place engine controls in a console between the pilot and co-pilot. Engine instruments are usually placed above the center console. Front and center for the pilot is the attitude indicator (artificial horizon). Grouped around it are related instruments: altitude indicator, airspeed indicator, heading indicator, rate of climb, and turn and bank; there are no more than a couple of standard layouts for these instruments. The only other controls/instruments that can look busy would be the radio and navigation equipment - often placed above the center console, either above or below the engine instruments. Other controls and indicators will have less standard placement because they may be specific to a type or model of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what it's worth: I acquired a private pilot's license many years ago, have logged very few hours, flew only Cessna 152,172 and a couple of models of single engined Pipers. All of these aircraft have relatively simple control panels. Nevertheless, I can look at a 747 instrument panel and, given a little time, figure out the purpose of everything there. It's because of the standardization of panel layout, and standardization of instrument labeling. An artificial horizon is always recognizable as such, as is an altimeter, airspeed indicator, etc.. Engine instruments are generally (if cryptically) labeled with the parameter they are indicating.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="3218" LastEditDate="2018-05-27T17:43:05.907" LastActivityDate="2018-05-27T17:43:05.907" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16858" PostTypeId="2" ParentId="16855" CreationDate="2015-07-14T02:58:49.593" Score="16" Body="&lt;p&gt;It depends on the airline and their planning capacity. The simple answer is that they can't be &lt;em&gt;sure&lt;/em&gt; of the tail number &quot;of record&quot; for a flight until the plane pulls into the gate at its destination. It's rare for a plane that departs the gate for a flight to not run that flight (it's pretty bad business for it to be common for flights to depart the gate and then come right back, or to be diverted, or otherwise not finish the route they left the gate to fly); it indicates a mechanical issue exists that did not develop and/or was not discovered until taxi or takeoff, and at some point in the flight (probably when departure control hands them off the the ARTCC) the plane could be said to have &quot;run&quot; the flight even if it ended up diverted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the equipment schedules (which tail number will fly which route at exactly what departure and arrival times) are generated by computer and can be set up months in advance if they really wanted to. However, that's usually an exercise in futility along the lines of predicting the weather more than a few days ahead. Airline scheduling, like weather, is susceptible to &quot;chaos theory&quot;, because small deviations from the initial plan tend to compound over time instead of factoring out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ticket sales, rebooks and cancellations will affect the schedule days and weeks in advance of the flight. It's technically illegal to cancel a flight less than a certain number of days before its scheduled departure if it has even a single paying customer on the roster, but if a route is underperforming, the scheduler can reduce the scheduled daily flights along that route which could bump people who bought a ticket far in advance. Also, an underbooked flight can legally be cancelled if the plane is needed for an equipment change on a fuller flight, as cancelling the underbooked flight would cause less overall disruption than cancelling the full flight because that plane can't make its next hop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just mentioned mechanicals; that's a &lt;em&gt;big&lt;/em&gt; reality check for a computer-generated schedule. If a plane cannot continue because of a mechanical defect, it gets pulled for maintenance. Airlines typically have a few planes parked strategically on the tarmac of various airports for a day, which can be activated to run a route, but they don't have too many of these since a parked aircraft isn't making money, and there isn't always one of these standby aircraft readily available as a substitute (though if a defect is found in flight the replacement can be on the way before the defective one lands to reduce the delay). Meanwhile, mechanicals are typically such a localized problem that the schedulers can't get away with just delaying flights systemwide, like they can often do with severe weather. They have to run the rest of their fleet on time, and that means either getting a replacement plane to the gate, pronto, or else sending that replacement plane empty to the cancelled flight's next destination, so the new plane can get those passengers on to their destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, severe weather can cause major ripples through an airline's schedule for days to come. If ORD or DFW has a &quot;ground stop&quot; due to severe precipitation or high winds, that will delay not only the flights scheduled to arrive or depart in that time, but every flight those tail numbers were scheduled to run for the rest of the day, &lt;em&gt;as well as&lt;/em&gt; various scheduled connectors (those connecting flights, if they're not also under severe weather, often have to depart with whatever passengers they have otherwise there will be even more delays; then the passengers who have missed that connectot will have to be rebooked, on other airlines if need be).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That delay time also counts as &quot;active&quot; time for a flight crew; if a flight is delayed beyond a crew's end of shift, they often must get off the plane to comply with FAA regs and union CBAs. The scheduled replacement crew, however, was supposed to get on at the next stop hundreds of miles away; so, it's not just the planes that have to be replaced on a route when a flight is cancelled. In cases of a severe delay extending beyond a normal shift change, the crew either flies the plane if it's legal and are paid overtime, or if it would be illegal for that crew to continue, an on-call crew is brought in, flies the plane to the scheduled changeover point, then rides a standby seat (or in the extreme an empty plane) back to their home terminal or somewhere else they'll be useful when their shift really starts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these considerations and more are weighed by the sophisticated algorithms now used to generate flight schedules. American Airlines calls theirs the &quot;cancellator&quot;, and when a major hub like DFW, ORD or ATL sees a weather shutdown that's pretty much exactly what it does, sacrificing flights to and from that hub and some of its connectors to try to save what it can of its passenger load for the day (and thus the airline's profitability for the quarter).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-27T22:51:18.153" LastActivityDate="2015-07-27T22:51:18.153" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16859" PostTypeId="2" ParentId="16855" CreationDate="2015-07-14T03:06:42.160" Score="7" Body="&lt;p&gt;How far ahead they formulate their plan will vary for each airline, but plans can change even as late as hours or even minutes before the flight, in case of things like broken planes or inoperative equipment that makes a swap necessary.  Say an aircraft that was going to operate a couple of long-haul flights &amp;amp; overnight at an out-station develops a problem with a center-tank fuel gauge. It might get swapped with an aircraft operating shorter legs (so the center tank would remain empty) that's scheduled to overnight at a maintenance base. This would get the gauge fixed sooner, and make for fewer issues for the long-haul crews.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you'd have a different tail number show up at your gate than was planned before the swap was put on.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-14T03:06:42.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16861" PostTypeId="2" ParentId="2873" CreationDate="2015-07-14T04:44:44.030" Score="10" Body="&lt;p&gt;For decades, the design theory of aircraft has been reliability above everything else. As other answers have said, you can't just pull over to the side of the road if you have a problem in flight. Taking off is optional; landing is mandatory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that basic mindset, aircraft cockpits are designed with some central principles:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Complete control. By FAA regs, every electrically-powered system on board an aircraft must be able to at least be turned on and off from the cockpit, even if the only way to do that is using the breaker panel. There are times when one instrument interferes with another, or when an instrument malfunctions and sends confusing signals to ground staff. In such cases the offending instrument has to be disabled. Additionally, instruments have to be adjusted and even recalibrated in-flight, so the ability to do so must be a part of their user interface. Lastly, short-circuit failures in-flight can drain the battery or overload the alternator, and so the affected system has to be disabled through the breaker panel to stop the short-circuit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rock-solid reliability. Again, you can't just pull over and call a tow-truck when your uber-fancy fly-by-wire system decides to take a break mid-flight. Every switch, button and display in the cockpit has to be rated for thousands of hours of use.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Proven technology over new sweetness. The previous point tends to favor designs with an established pedigree, from entire airframes like the venerable Cessna 172 all the way down to design and production of the toggle switches for the external lights. In the aviation world, you don't just show up with a fancy new touchscreen and make everything that has come before it useless. We're still using instrument technology that was standard on planes by the end of the First World War almost a century ago.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Modular simplicity. Within the confines of a single flight instrument, everything about that instrument should be intuitive to someone with a basic knowledge of how that device is supposed to function, and that knowledge should be as general as possible. That allows the total number of additional flight instruments and other controls to grow as the airplane becomes more complex and the conditions it flies in more demanding, without sacrificing this basic simplicity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These general concepts lend themselves to a cockpit design where there is a unique display for every piece of information you need to know, and a unique switch, button, knob or lever for every task you might need to perform. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a glider, that's not much; other than manipulating flight surfaces, your airspeed, altitude, sink rate and a few other measurements are important, and to talk to anyone outside the aircraft you need a radio, but as there's no engine, there's no throttle, no mixture knob, no tachometer and no oil pressure gauge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of those controls and gauges become necessary once you have an engine, along with a magnetos switch to control the ignition system, but these additional controls are all you need in something like an ultralight, where you're just flying in the day in good weather. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying at night, now you need to control your running and landing lights as well as cabin and panel lights in the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying in bad weather, you need a few more tools, like an artificial horizon and navigation systems either based on radio ground stations or satellites. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding additional features of the powerplant requires the means to control them; variable-pitch propellers (constant-speed) requires a blade pitch control in the cockpit, usually next to the throttle. Adding a second engine means you need a second throttle, mixture knob and tach/oil gauges. Upgrading to jet engines means you need a battery of additional monitoring devices, and before the advent of computer automation, this required a third person to sit on the flight deck just to monitor and maintain the jet engines of a large airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, complexity of the cockpit increases as you increase the complexity of the machine. A modern airliner is a very complex machine indeed, with hundreds or thousands of miles of electrical wiring in a modern fly-by-wire airframe like the A380 or 787. A 172, not so much, by comparison. A light sport aircraft can be downright carlike; tachometer, spedometer, engine temp, fuel gauge... other than the altimeter, practically everything you'd have access to in a sport aircraft has a direct counterpart in your car.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-27T22:42:33.640" LastActivityDate="2015-07-27T22:42:33.640" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16862" PostTypeId="1" AcceptedAnswerId="16866" CreationDate="2015-07-14T05:19:14.533" Score="23" ViewCount="6187" Body="&lt;p&gt;Modern airliners like the Airbus A380 and Boeing 787 have bigger windows than older designs, like the Boeing 737 and Airbus A320. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What factors have led to this change of window size, opposite to the trend of almost every other thing in the interior of the plane becoming smaller in size (like the seats).&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="1696" LastEditDate="2015-10-07T14:37:18.653" LastActivityDate="2015-10-07T14:37:18.653" Title="What are the factors behind increasing aircraft window sizes?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;cabin-design&gt;&lt;windows&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16863" PostTypeId="2" ParentId="16847" CreationDate="2015-07-14T05:38:20.803" Score="56" Body="&lt;ol&gt;&#xA;&lt;li&gt;Because the pitch of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuselage#Semi-monocoque&quot; rel=&quot;noreferrer&quot;&gt;frames&lt;/a&gt; is not related to the pitch of the seats. The windows placement have to cut through as few frames as possible.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You can see it in the following picture, noting that frames are &quot;highlighted&quot; by the vertical riveting&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xVjnm.jpg&quot; alt=&quot;Riveting around an aircraft window&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image &lt;a href=&quot;http://www.b737.org.uk/fuselage.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is even more evident in the picture contained in &lt;a href=&quot;https://ux.stackexchange.com/a/73296/67557&quot;&gt;this answer&lt;/a&gt; on UX.SE:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8cEIl.jpg&quot; alt=&quot;Windows vs Fuselage frames&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Because the aircraft is designed once, but &quot;decorated&quot; by several airlines in several different manners. For example, an A320 or a B757 will have the windows always in the same locations, but depending on the airline that is using it, it will most probably have the seats in slightly different locations.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:32:24.050" LastActivityDate="2015-07-14T11:01:51.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16864" PostTypeId="2" ParentId="16862" CreationDate="2015-07-14T06:55:25.800" Score="7" Body="&lt;p&gt;Let me answer with a car analogy: In most cases, the next car model is larger than the one before. Similarly, the aircraft manufacturers make the windows a little bigger with every new model, just to have another argument why the new model is better than all the competition. This costs a little weight, but seems to be worth it for the airlines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-15T20:17:18.697" LastActivityDate="2015-07-15T20:17:18.697" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16865" PostTypeId="2" ParentId="16862" CreationDate="2015-07-14T07:25:23.820" Score="14" Body="&lt;p&gt;I think engineering knowledge is an important factor, going from the time of the first 737 to the A380, there was a huge development in engineering techniques. Better material knowledge, more advanced modeling methods (such as Finite Elements) and better knowledge of structural optimization have improved the situation. Especially with windows, where a lot is happening due to stress concentrations, this improved knowledge makes a difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that bigger windows might still lead to an increase in weight, but there will be a less severe weight penalty than the same windows using B737 age techniques.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-07-14T12:48:32.710" LastActivityDate="2015-07-14T12:48:32.710" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16866" PostTypeId="2" ParentId="16862" CreationDate="2015-07-14T08:52:34.900" Score="32" Body="&lt;p&gt;In the early years of the jet age, which followed closely on the introduction of &lt;a href=&quot;https://en.wikipedia.org/wiki/Cabin_pressurization&quot; rel=&quot;noreferrer&quot;&gt;pressurized hulls&lt;/a&gt;, there was much fear of stresses &lt;strong&gt;specifically in the area of the window openings&lt;/strong&gt; due to the loss of two &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;noreferrer&quot;&gt;DeHavilland Comets&lt;/a&gt;. Subsequent Comet hulls had different shaped, rounded, smaller windows and that trend continued in other pressurized, typically jet-powered, aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DUYQw.jpg&quot; alt=&quot;Comet window failure&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only with modern CAD systems and new materials knowledge could windows be made larger again. The newest aircraft designs reflect that progress.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="354" LastEditDate="2015-07-15T05:34:22.130" LastActivityDate="2015-07-15T05:34:22.130" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16867" PostTypeId="2" ParentId="16862" CreationDate="2015-07-14T09:12:30.280" Score="5" Body="&lt;p&gt;One of the important things I'd like to add to the previous answers is that the old air-crafts used to have smaller windows to accommodate for the rate of cabin depressurization in case of an emergency. The old airplanes had much smaller windows to control the cabin depressurization rate in case of some emergency (some window actually breaking to cause hull breach). But with advancement in the design methods and manufacturing process and with the introduction of the newer materials for airplane manufacturing, it has become possible to increase the size of the windows without increasing the risk factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to this, creating an ambient atmosphere for the passengers inside the airplane without increasing the cost of the flight has always been a priority. So, while decreasing the seat spacing to accommodate more passengers is being done to reduce flight cost, the increase in the size of the windows does not have determinal effect on the travel cost, and hence is favored to create a less claustrophobic atmosphere inside the plane.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-14T09:12:30.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16868" PostTypeId="2" ParentId="16847" CreationDate="2015-07-14T09:17:43.027" Score="7" Body="&lt;p&gt;When an aircraft is designed, the hull is designed in terms of 'frames' which actually support the main hull of the fuselage. Some air-crafts have provision to include more frames (upto some limit) to increase the length of the plane if later modifications are required. Now, the windows are placed in a regular spacing depending upon the length of each frame on the hull (so basically windows are spaced to remain in between the frames), and this pattern is determined after loads simulation on the aircraft's hull.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once designed, the insides of the airplane can be modified at will (as this does not determine the 'safety' of the aircraft much), and this is when airliners try to persuade the manufacturer to put seats in a fashion that they can get the desired revenue. This independence in the hull frame spacing and the seat spacing is why the windows are not aligned with the seats.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-14T09:17:43.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16869" PostTypeId="1" CreationDate="2015-07-14T09:39:42.127" Score="1" ViewCount="610" Body="&lt;p&gt;How does opening airplane bay doors (especially in the case of bombers), increase the radar cross section of the airplane and make it &lt;strong&gt;more visible&lt;/strong&gt; to the radar?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These are usually combined with active measures such as carefully planning all mission maneuvers in order to minimize the aircraft's radar cross section, since common actions such as hard turns or opening bomb bay doors can more than double an otherwise stealthy aircraft's radar return&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Stealth_aircraft&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="19" LastEditDate="2016-11-21T09:17:26.257" LastActivityDate="2016-11-21T09:17:26.257" Title="What is the effect of opening airplane bay doors on the radar cross section of the airplane?" Tags="&lt;radar&gt;&lt;stealth&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16870" PostTypeId="2" ParentId="16869" CreationDate="2015-07-14T11:27:55.847" Score="4" Body="&lt;p&gt;Radar waves are sent back to the radar by two mechanisms, reflection and diffraction.  Opening a bay door may present a surface that is angled such that waves will be reflected to the radar.  As for diffraction, low observable (stealth) aircraft are designed so that a radar wave encountering the aircraft's skin will travel along the skin and be gradually absorbed.  Opening the bay doors creates a break in the skin, causing waves on the skin to diffract.  Some of the radar energy is returned to the sender.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an amateur looking at &quot;stealth&quot; diffraction is often not accounted for.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-07-14T11:27:55.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16871" PostTypeId="1" AcceptedAnswerId="16872" CreationDate="2015-07-14T11:29:50.147" Score="22" ViewCount="1800" Body="&lt;p&gt;It seems there are many scientific laser ranging stations around the globe and some are mobile. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MYZGs.jpg&quot; alt=&quot;Scientists Bounce Laser Off Soviet Lunar Rover&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;Scientists Bounce Laser Off Soviet Lunar Rover Lost On Moon Decades Ago. &lt;a href=&quot;http://www.huffingtonpost.com/2013/04/30/laser-soviet-lunar-rover-moon-lunokhod-1_n_3186212.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How dangerous are those scientific laser beams for passengers and crew, and for the aircraft?&lt;/li&gt;&#xA;&lt;li&gt;Is there a NOTAM or a temporary flight restriction associated with scientific laser activity?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;a href=&quot;https://en.wikipedia.org/wiki/Satellite_laser_ranging&quot; rel=&quot;noreferrer&quot;&gt;satellite laser ranging&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In satellite laser ranging (SLR) a global network of observation&#xA;  stations measures the round trip time of flight of ultrashort pulses&#xA;  of light to satellites equipped with retroreflectors. This provides&#xA;  instantaneous range measurements of millimeter level precision which&#xA;  can be accumulated to provide accurate measurement of orbits and a&#xA;  host of important scientific data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pnqNt.jpg&quot; alt=&quot;International Laser Ranging Service&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;International Laser Ranging Service - Map of stations. &lt;a href=&quot;http://ilrs.gsfc.nasa.gov/network/stations/ILRS_Stations_Map.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and for &lt;a href=&quot;http://www.lpi.usra.edu/lunar/missions/apollo/apollo_11/experiments/lrr/&quot; rel=&quot;noreferrer&quot;&gt;the Moon&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Laser beams are used because they remain tightly focused for large&#xA;  distances. Nevertheless, there is enough dispersion of the beam that&#xA;  it is about 7 kilometers in diameter when it reaches the Moon and 20&#xA;  kilometers in diameter when it returns to Earth. Because of this very&#xA;  weak signal, observations are made for several hours at a time. By&#xA;  averaging the signal for this period, the distance to the Moon can be&#xA;  measured to an accuracy of about 3 centimeters.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For &lt;a href=&quot;https://en.wikipedia.org/wiki/Laser_guide_star&quot; rel=&quot;noreferrer&quot;&gt;astrophysics&lt;/a&gt; purposes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Adaptive optics systems require a wavefront reference source in order&#xA;  to correct atmospheric distortion of light. Sufficiently bright stars&#xA;  are not available in all parts of the sky [...], one can create an&#xA;  artificial guide star by shining a laser into the atmosphere.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;See also&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thanks to Federico, a very nice &lt;a href=&quot;http://sgphotos.com/portfolio/timelapse/makingmaunakeaheavens/&quot; rel=&quot;noreferrer&quot;&gt;timelapse video of laser activity&lt;/a&gt; at Mauna Kea (by Sean Goebel).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-10-12T08:48:58.060" LastActivityDate="2015-10-12T08:48:58.060" Title="How does aviation deal with satellite and Moon laser ranging, and other scientific lasers in the sky?" Tags="&lt;airspace&gt;&lt;security&gt;&lt;notam&gt;&lt;laser-illumination&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16872" PostTypeId="2" ParentId="16871" CreationDate="2015-07-14T11:41:23.110" Score="20" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;Is there a NOTAM or a temporary flight restriction associated with laser ranging activity?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.laserpointersafety.com/news/news/other-news_files/b5976263598649b8c87a8c4e7b1081cc-357.php&quot; rel=&quot;noreferrer&quot;&gt;Apparently&lt;/a&gt; yes:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The lasers on the telescopes are in the range of 15-40 watts. The FAA calls a no-fly zone over the area when a laser is in use, and two people have to stand around outside in the freezing temperatures and watch for airplanes. Each of them has a kill switch to turn off the laser in case an airplane comes near. [...]&lt;/p&gt;&#xA;&lt;p&gt;To clarify, the FAA does not have a no-fly zone, but instead issues a “Notice to Airmen” or NOTAM about the laser operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I also worked on an Adaptive Optics project and it was given for granted that NOTAMs would be issued by the people in charge of the experiments.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://tfr.faa.gov/save_pages/notam_actual_0_7651.html&quot; rel=&quot;noreferrer&quot;&gt;Example&lt;/a&gt; of NOTAM:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FDC 0/7651 ZDC .. SPECIAL NOTICE .. LASER OPERATIONS EFFECTIVE&#xA;1005010001 UTC UNTIL 1112312359 UTC. SCIENTIFIC AND RESEARCH LASER&#xA;OPERATIONS WILL BE CONDUCTED AT THE NASA GODDARD SPACE CENTER IN&#xA;GREENBELT, MARYLAND, LOCATED AT 390113N/764939W. THE SYSTEM IS&#xA;INTERMITTENT, WITH POSSIBLE OPERATIONS HAPPENING 24 HOURS A DAY, 7&#xA;DAYS A WEEK. THE LASER BEAM MAY BE INJURIOUS TO PILOTS/AIRCREWS AND&#xA;PASSENGERS EYES FOR A DISTANCE OF 98,000 FEET ABOVE GROUND LEVEL.&#xA;HOWEVER, THIS SYSTEM USES A LASER HAZARD REDUCTION SYSTEM RADAR THAT&#xA;IS SLAVED TO THE TELESCOPE MOUNT TO ENSURE THE LASER IS DEACTIVATED IN&#xA;THE EVENT AN AIRCRAFT APPROACHES. THE AREA WILL ALSO BE MONITORED BY&#xA;OBSERVERS AND THE LASER BEAM WILL BE TERMINATED IF NONPARTICIPATING&#xA;AIRCRAFT ARE DETECTED. LASER IRRADIANCE LEVELS WILL NOT EXCEED THE&#xA;MAXIMUM PERMISSIBLE EXPOSURE LEVELS WITHIN THE LASER FREE, CRITICAL&#xA;FLIGHT, AND SENSITIVE FLIGHT ZONES. OTHER VISUAL EFFECTS, E.G.,&#xA;FLASHBLINDNESS, AFTER IMAGE, GLARE, AND DISTRACTION MAY OCCUR AT&#xA;GREATER DISTANCES. THE POTOMAC TRACON /PCT/ PHONE NUMBER 540-349-7541&#xA;IS THE FAA COORDINATION FACILITY.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;How dangerous is a laser beam for passengers and crew, and for the aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For the aircraft (meaning the hull) it is no danger, 40 watts of unfocused power (astronomers do not need laser beams in the sky as focused as the beams in an optics lab) do not affect the hull.&lt;/p&gt;&#xA;&lt;p&gt;For the eyes of pilots and passengers it can instead be extremely dangerous, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2817/why-is-laser-illumation-of-a-cockpit-an-emergency&quot;&gt;Why is laser illumation of a cockpit an emergency?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-14T11:52:25.537" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16873" PostTypeId="2" ParentId="16852" CreationDate="2015-07-14T12:23:22.693" Score="10" Body="&lt;p&gt;Yes. The tail numbers are indeed places on a placard inside the cockpits of commercial airplanes. Following are some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5gSkA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/5YK92.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-14T12:23:22.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16874" PostTypeId="1" CreationDate="2015-07-14T12:43:44.117" Score="17" ViewCount="1746" Body="&lt;p&gt;Aircraft manufacturers are now planning to use High Torque electric motors on the nose wheel of the aircraft, which is powered from the APU, to taxi the aircraft from the gate to the runway without using its main engines. This is intended to reduce the fuel consumption by the plane while being taxied using the main engines, but also adds additional 150 kgs approximately to the weight of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much fuel savings are we talking about here? Lets say we are considering an A320?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="3386" LastEditDate="2015-07-14T14:39:17.547" LastActivityDate="2021-01-24T02:20:04.513" Title="What is the cost savings of using electronic motors to taxi?" Tags="&lt;aircraft-design&gt;&lt;fuel&gt;&lt;taxiing&gt;&lt;efficiency&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16876" PostTypeId="1" CreationDate="2015-07-14T13:31:42.120" Score="16" ViewCount="10052" Body="&lt;p&gt;According to the wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Stealth_aircraft&quot;&gt;article&lt;/a&gt;, a stealth plane requires the following features in order to reduce its radar signature and thermal detection:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Reducing thermal emission from thrust&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Reducing radar detection by altering some general configuration (like introducing the split rudder)&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Reducing radar detection when the aircraft opens its weapons bay&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Reducing infra-red and radar detection during adverse weather conditions&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How do aircraft actually achieve reduction in their thermal emission from thrust?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="5517" LastEditDate="2015-07-14T15:03:20.347" LastActivityDate="2015-09-04T16:09:54.760" Title="How do stealth aircraft reduce the Heat Signature?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;stealth&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16877" PostTypeId="1" AcceptedAnswerId="16878" CreationDate="2015-07-14T13:50:07.447" Score="2" ViewCount="1003" Body="&lt;p&gt;&lt;strong&gt;Context&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crews are skilled and well trained.&lt;/li&gt;&#xA;&lt;li&gt;In a crew of two, one can fix others confusion.&lt;/li&gt;&#xA;&lt;li&gt;There is a flight plan, ATC can inform of a deviation.&lt;/li&gt;&#xA;&lt;li&gt;GNSS / ILS / VOR / DME frequencies and distances increase situational awareness.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But still:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;February 2014: &quot;&lt;em&gt;&lt;a href=&quot;http://www.nydailynews.com/news/national/pilots-head-wrong-airports-article-1.1608410&quot; rel=&quot;nofollow&quot;&gt;Planes landed at wrong airports 150 times over 2 decades&lt;/a&gt;&lt;/em&gt;&quot;.&lt;/li&gt;&#xA;&lt;li&gt;March 2014: &lt;a href=&quot;http://www.ntsb.gov/safety/safety-alerts/Documents/SA_033.pdf&quot; rel=&quot;nofollow&quot;&gt;Security Alert&lt;/a&gt;, NTSB reminded pilots to take care of not landing at the wrong airport.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;After having posted this question, I did an additional research, to find NTSB came back to this problem recently, in May 2015:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;NTSB releases &lt;a href=&quot;http://www.ntsb.gov/safety/safety-recs/recletters/A-15-009-010.pdf&quot; rel=&quot;nofollow&quot;&gt;two recommendations to FAA&lt;/a&gt;. One for ATC clearing to land, the other for software detection of wrong location.&lt;/li&gt;&#xA;&lt;li&gt;Related article: &quot;&lt;a href=&quot;http://roadwarriorvoices.com/2015/05/06/after-5-planes-land-at-wrong-airports-the-ntsb-has-a-few-words-of-advice-for-the-faa/&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;After 5 planes land at wrong airports, the NTSB has a few words of advice for the FAA&lt;/em&gt;&lt;/a&gt;&quot;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Relatively few errors, but consequence could be tragic&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;150 approaches or so wrong are &lt;em&gt;a very small fraction&lt;/em&gt; of the many millions of flawless flights, however the NTSB emphasizes the consequences could have been tragic, e.g. if the erroneous airport didn't provide the expected runway length.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Did the analysis of these incidents show distinct patterns in their occurrence that could be prevented by different procedures or different navigation instruments?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Did the involved pilots, or other professionals think specific improvements had or still have to be made to avoid recurrence?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-07-14T19:04:44.800" LastActivityDate="2021-05-04T18:12:02.427" Title="What is supposed to prevent a commercial crew from flying to the wrong airport?" Tags="&lt;commercial-aviation&gt;&lt;navigation&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16878" PostTypeId="2" ParentId="16877" CreationDate="2015-07-14T14:14:59.447" Score="3" Body="&lt;p&gt;According to the Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow&quot;&gt;IFR&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VFR is the most common mode of operation for small craft. However, it is only safe to fly VFR when these outside references can be clearly seen from a sufficient distance; when flying through or above clouds, or in fog, rain, dust or similar low-level weather conditions, these references can be obscured.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically, a pilot would land at a &lt;strong&gt;wrong&lt;/strong&gt; airport due to one of the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;He/She did not have previous experience of landing at the said airport&lt;/li&gt;&#xA;&lt;li&gt;He/She paid more attention to VFR that IFR (which is usually suggested), and the proximity of the airports confused him/her&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Any aircraft operating under VFR must have the required equipment on board, as described in FAR Part 91.205[5] (which includes some instruments necessary for IFR flight). VFR pilots may use cockpit instruments as secondary aids to navigation and orientation, but are not required to; the view outside of the aircraft is the primary source for keeping the aircraft straight and level (orientation), flying to the intended destination (navigation), and not hitting anything (separation).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that a pilor following VFR can get confused, and that would be a completely manual error. To prevent this from happening, he/she should raise a flag with the Control Tower before landing if his IFR shows a different destination, when compared to the place he is intending to land at following VFR.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-07-14T14:14:59.447" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16879" PostTypeId="2" ParentId="16874" CreationDate="2015-07-14T15:10:07.680" Score="13" Body="&lt;p&gt;Jet engines are not very efficient at low power and speeds, so using an alternative method of propulsion is a good opportunity to save fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft the size of an A320 will probably burn about 200 kg of fuel during taxi (based on &lt;a href=&quot;http://www.hilmerby.com/fom/proc_fuel.html&quot;&gt;this&lt;/a&gt; and &lt;a href=&quot;http://www.bangaloreaviation.com/2014/05/tech-tuesdays-fuel-planning-much-must-carry.html&quot;&gt;this&lt;/a&gt;). Assuming fuel costs \$3 per gallon, this is about \$200 per flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost of the added weight from the electric motor will vary based on flight length, but assuming \$0.05 per pound, the extra cost would be \$16.50. Of course you are saving 200 kg of fuel, so this also helps to offset the weight. The electric motor is powered by the APU which uses much less fuel than the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As KeithS points out, this adds up quickly. Even if United Airlines only equips its &lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines&quot;&gt;150&lt;/a&gt; A320 series planes with this equipment (which would certainly be a large upfront cost), and those planes make 5 flights each per day, that adds up to \$150,000 in savings every day. This will of course depend on fuel prices, which are actually &lt;a href=&quot;http://www.forbes.com/sites/danielreed/2015/04/27/dont-believe-everything-you-read-lower-fuel-prices-arent-why-us-airlines-are-earning-big-profits/&quot;&gt;well under $3/gal at the moment&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple way to save some fuel while taxiing is to &lt;a href=&quot;http://www.aviationtoday.com/regions/weur/Engine-off-taxiing-picks-up-speed_36060.html&quot;&gt;only use 1 engine&lt;/a&gt; (or 2, for four engine planes) to taxi. This doesn't save as much fuel as the electric option, but also has much less upfront cost.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-07-14T15:52:52.520" LastActivityDate="2015-07-14T15:52:52.520" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16880" PostTypeId="2" ParentId="16869" CreationDate="2015-07-14T15:21:18.777" Score="3" Body="&lt;p&gt;In addition to creating a surface that could better reflect radar and breaks that can diffract the radar, the interior of the bomb bay is exposed. The exterior skin of stealth aircraft is specially treated to reduce radar returns, so the untreated interior of the weapons bay and bay doors will also create a much larger radar return than even the exterior surfaces of the open doors.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-07-14T15:21:18.777" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16881" PostTypeId="1" AcceptedAnswerId="16883" CreationDate="2015-07-14T15:27:37.983" Score="14" ViewCount="1636" Body="&lt;p&gt;We have had a &lt;a href=&quot;https://aviation.stackexchange.com/questions/2873/why-are-the-cockpit-controls-of-airplanes-so-complicated&quot;&gt;blockbuster question&lt;/a&gt;, asking about the complexity of the cockpit, which was answered very well. With so many controls, are there any flight- or safety-critical functions which &lt;em&gt;cannot&lt;/em&gt; be controlled by the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-22T22:13:53.127" Title="Is there some functionality of an airliner which is not controlled by the cockpit?" Tags="&lt;flight-controls&gt;&lt;cockpit&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16882" PostTypeId="2" ParentId="16881" CreationDate="2015-07-14T15:44:10.107" Score="4" Body="&lt;p&gt;The doors (through which the passengers board or disembark) are not in control of the cockpit, in an airliner. There may be signals indicating the state of the doors (and their locks), but the doors themselves are opened or open-able manually.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastActivityDate="2015-07-14T15:44:10.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16883" PostTypeId="2" ParentId="16881" CreationDate="2015-07-14T15:46:29.130" Score="16" Body="&lt;p&gt;You cannot (as far as I know),&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flush the toilets &lt;/li&gt;&#xA;&lt;li&gt;Control the IFE system (aside from possibly pulling the breaker to shut it off)(there seems to be some debate on this one and it could vary by plane/system)&lt;/li&gt;&#xA;&lt;li&gt;Open the doors (of a passenger plane, cargo planes this may be possible) &lt;/li&gt;&#xA;&lt;li&gt;Update the software for glass cockpit planes (if the computers are not located in the cockpit). I'm still looking for the link but FMS units are updated via USB on a unit usually housed with the other flight computers which is often below the cockpit. &lt;a href=&quot;https://www.youtube.com/watch?v=g4TA3Or6bDU&quot;&gt;In some smaller planes&lt;/a&gt; these units are in the cockpit as are the USB ports so this may only hold for some aircraft.   &lt;/li&gt;&#xA;&lt;li&gt;General passenger tasks (reading lights etc). Although it should be noted that generally speaking the master breakers are in the cockpit so while they may not have control over individual system components (e.g. single reading lights) they can often shut them down completely if need be. &lt;/li&gt;&#xA;&lt;li&gt;Ovens (for heating meals) and coffee machines. Only circuit breakers are in cockpit again (and they are needed; faults in these things cause relatively high fraction of diversions).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="524" LastEditDate="2015-07-14T15:59:24.033" LastActivityDate="2015-07-14T15:59:24.033" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="16884" PostTypeId="2" ParentId="16832" CreationDate="2015-07-14T15:54:58.210" Score="4" Body="&lt;p&gt;I've only got about 300 hours logged but I have not once been asked WHY I am going around. However if you &quot;intend&quot; to do a touch-and-go or an abort/go around you must inform them, because it's their job to know where every aircraft is going. I usually tell the tower before takeoff I'll be flying a &quot;closed pattern&quot; if just practicing TnGs. Makes it much easier for ATC. When I intend to stop, I will say landing &quot;Full Stop&quot; when turning final. But, as Farhan said, if anything is off on approach or you bounce on touchdown, miss the touchdown zone, wind starts kicking your ass or if ANYTHING isn't perfect, it's full throttle, flaps up once +ROC, and figure out what u did wrong. The tower can wait, they are all in there watching, laughing at your pathetic attempt anyway. If something is wrong, do insist on priority access! POC is in charge after all. My alternator 172SP died on climbout once and I didn't say a thing, just rushed to mid field and dove vertical out of downwind pattern, slipping the hell out of it to slow her down. Per protocol, I didn't say a word to ATC until I was clear of the runway. But always be nice to the ATC. Fantastic guys that would do ANYTHING to keep their pilots safe. The FAA/NTSB tho.... they are the best reason to keep your mouth shut unless you are out of options!&lt;/p&gt;&#xA;" OwnerUserId="9367" LastActivityDate="2015-07-14T15:54:58.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16885" PostTypeId="2" ParentId="16876" CreationDate="2015-07-14T16:04:55.373" Score="3" Body="&lt;p&gt;While they try to reduce it as best they can its often low on the list, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The SR-71 was designed to minimize its radar cross-section, an early attempt at stealth design.[21] Finished aircraft were painted a dark blue, almost black, to increase the emission of internal heat&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One of the problems you get at is that airframes heat up at high speeds. In the case of the blackbird it was fast enough (and could fly high enough) to outrun anything anyway so heat signature was less of a concern. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://science.howstuffworks.com/stealth-bomber3.htm&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the B-2, all of the exhaust passes through cooling vents before flowing out of the rear ports&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it seems they cool the exhaust. Im not sure what effects this has on the over all thrust that the plane generates but Im sure it has an effect in some way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article also goes on to talk about the exhaust placement and how top mounted exhaust can help with ground based sensing that is looking up at the bottom of the craft&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Putting the exhaust ports on the top of the plane further reduces the infrared signature, since enemy sensors would most likely scan below the plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reducing heat signature has 2 main functions. To keep the plane from showing up on ground based heat sensing systems and to keep thermal guided weapons from locking on. For what its worth the SR-71 was able to outrun most missiles of the time, &lt;a href=&quot;http://sploid.gizmodo.com/5511236/the-thrill-of-flying-the-sr-71-blackbird&quot; rel=&quot;nofollow&quot;&gt;some 4000&lt;/a&gt; by all accounts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.citizendium.org/wiki/SR-71_Blackbird&quot; rel=&quot;nofollow&quot;&gt;For what its worth&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the SR-71 design did not take into account the extremely hot engine exhaust and the particles in the hot exhaust reflect radar extremely well. Ironically, the SR-71 was one of the largest targets on the FAA (Federal Aviation Administration) long range radars, which were able to track the plane at several hundred miles&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So arguably the greatest spy plane of all time was not even that stealthy... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.centennialofflight.net/essay/Evolution_of_Technology/Stealth_aircraft/Tech31.htm&quot; rel=&quot;nofollow&quot;&gt;In regards to the F-117&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;exhaust was channeled through long narrow ducts lined with heat-absorbing material so that it was cooler by the time it exited the plane and therefore did not show up as well on heat detectors&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Seems similar to the system employed on the B2&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-14T16:33:14.850" LastActivityDate="2015-07-14T16:33:14.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16886" PostTypeId="2" ParentId="16876" CreationDate="2015-07-14T17:13:06.363" Score="17" Body="&lt;p&gt;The short of it is that it's really hard to hide the heat signature of a device that is powered by burning large amounts of kerosene and shoving those gases out behind it. IR stealth is therefore a secondary concern (or lower) to designers of stealth fighters, primarily because the IR signature only matters at much closer ranges where stealth technology itself has reduced value (you can hide from radar, and camouflage to an extent, but you can't disappear entirely from visual range).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are some things that can be done to make an aircraft less than blindingly obvious to IR sensors. Here are a few:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;High bypass.&lt;/strong&gt; Not all of the air that enters a turbofan engine's intake enters the actual combustion chamber. Bypass air helps to cool the hot combusted air before it exits, reducing the IR signature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-10, not a &quot;stealth&quot; aircraft in the slightest, nevertheless operates in situations where MANPADS (shoulder-fired SAMs) are a big threat, so to reduce its IR signature it uses some of the highest-bypass turbofans ever put on a military single-seater, at a 6:1 bypass ratio. These high bypass engines, however, reduce performance at high altitudes and high airspeeds; neither disadvantage is a problem for the low, slow A-10's mission profile, but for a more high-performance air superiority fighter this is a big deal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;High-performance jet engines in fighters tend to be relatively low bypass compared to airliner engines for this reason. The F-15 and F-16 were powered by a P&amp;amp;W turbofan with just 0.36:1 bypass ratio, however this only increases IR signature by requiring higher fuel flow rates for the same thrust at lower speeds (lower bypass also reduces the effect of afterburners because there is less unburned bypass air to feed the additional combustion). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 mitigates the efficiency losses of a turbofan with a variable bypass intake system, allowing it to function as a turbofan with similar bypass to other fighters (about 0.3:1) at low speeds and altitudes, but converting to a near-turbojet configuration (almost zero bypass) at high altitudes and supersonic speeds, which is more fuel-efficient than an afterburner (and so allows the F-22 to supercruise).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Exhaust baffles.&lt;/strong&gt; The thing designers typically want to avoid at all costs is exposing the actual point of ignition and primary combustion in a jet engine to the ground; this makes the hottest part of a plane's visible IR signature within the plane itself instead of the stream of hot air behind it, allowing easy targeting by IR SAMs. Imagine being an SA-13 &quot;Gopher&quot; mobile SAM launcher and having these twin fireballs from an F-15E for a target:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/M1pz6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To hide this massive heat source, stealth aircraft are designed with exhaust vents that mask the exit point of the engine's exhaust from observation by the ground. There's really not a lot you can do design-wise to mask the IR signature from directly behind the aircraft; it's the pilot's job to ensure nobody ends up at that angle within missile range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Northrop is a fan of directing exhaust out over the top of their fuselage designs. Here's the B-2; you can see the heat plumes of the exhaust trail, but the source of actual combustion is well within the engine housing, and with the aircraft at any altitude the exhaust vent itself would be totally obscured:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4wYzb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the exhaust channels of the YF-23, which incorporated lessons learned from the B-2; notice the similarities in the strategy for directing the exhaust out over the top of the aircraft's trailing edge:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/47XH4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 Raptor uses a similar theory of tucking the engines way back behind exhaust ducts, but these ducts can move to vector thrust or open to allow afterburners, so for greatest effect the ducts are placed to the rear instead of over the top of the fuselage as Northrop's designs tend to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xoWOW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;EMR-absorbing materials.&lt;/strong&gt; A basic part of stealth design is the use of materials that absorb radar, and designing the aircraft's surfaces with angles that minimize the number of surfaces providing a direct return at any angle, while remaining aerodynamic. Other materials can absorb other frequencies in the EMR spectrum including IR; the Space Shuttle's lower and leading surfaces were covered in special ceramic tiles that could absorb enormous amounts of thermal energy while being cool to the touch. A similar material, not quite as effective but also less delicate, is used to protect the exhaust ducts of stealth fighters, and this has a secondary effect of lowering the radiant heat signature of the engines because the exhaust nozzles stay cooler. The radar absorbing material used elsewhere has some capacity for absorbing heat on leading edges, which helps avoid good lock-on by all-aspect IR missiles, but it's not the material's primary job.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In summary, designers do try to minimize IR signature, but tactically, if an enemy can launch an IR missile at you you have already failed at being stealthy. An infrared missile launch requires the launcher to tell the missile where to look, and that means they must at least be able to look at you themselves (using helmet-cued AA missiles), if not point the missile itself or the tracking radar at you. The idea of stealth is to minimize the amount of time the enemy knows that you exist by being invisible on radar, so they can't see you coming until they spot you visually, at which point they're either already dead or have mere seconds to react. Then for a ground run it's &quot;one pass and haul ass&quot; to avoid reprisals from anti-aircraft systems, while for an air-to-air engagement the first plane to launch a missile has an extreme advantage (and thus the advantage starts with the first plane to know where the other one is).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-04T16:09:54.760" LastActivityDate="2015-09-04T16:09:54.760" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16888" PostTypeId="1" AcceptedAnswerId="16889" CreationDate="2015-07-14T18:26:39.327" Score="5" ViewCount="4536" Body="&lt;p&gt;What are the visa types (H1b, L1b, H4, L2, J1, etc) accepted by TSA to learn flying for recreational purposes?&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;UPDATE 1&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I found some further information from &lt;a href=&quot;http://www.nafinet.org/news.aspx?id=370&quot; rel=&quot;nofollow&quot;&gt;National association of flight instructors&lt;/a&gt;, According to them; Person on work visa can follow Part 61 course and get the PPL.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;UPDATE 2&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I have received the permission from the TSA to flow the Category 3 flight training. It took around 1 &amp;amp; 1/2 weeks to process and it will cost around 130 for the application and 99 for fingerprint process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on this process, I understood that L1 Or L2 Or H1 Or H4 holders are eligible with the right set of document and no criminal record.&lt;/p&gt;&#xA;" OwnerUserId="9353" LastEditorUserId="9353" LastEditDate="2015-07-28T02:34:54.407" LastActivityDate="2016-06-03T23:01:32.967" Title="What type of visa is required to be allowed to earn a PPL in the US?" Tags="&lt;flight-training&gt;&lt;ppl&gt;&lt;tsa&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16889" PostTypeId="2" ParentId="16888" CreationDate="2015-07-14T18:47:47.520" Score="3" Body="&lt;p&gt;For a foreigner to come to USA to learn to fly, one would need an &lt;a href=&quot;https://en.wikipedia.org/wiki/F_visa&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-1&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/M-1_visa&quot; rel=&quot;nofollow noreferrer&quot;&gt;M-1&lt;/a&gt; visa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flyingmag.com/training/flight-school-getting-student-foreign-visa&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article in Flying magazine&lt;/a&gt; provides some information. You can get more information on &lt;a href=&quot;https://www.afa.edu/pilot-programs/international-pilot-training/&quot; rel=&quot;nofollow noreferrer&quot;&gt;from this school&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt;. Also, you can look at this meta question: &lt;a href=&quot;https://aviation.meta.stackexchange.com/q/1506/65&quot;&gt;Can I ask about details of coming to the US to get a PPL?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that you are already in the US on &lt;a href=&quot;https://en.wikipedia.org/wiki/H-1B_visa&quot; rel=&quot;nofollow noreferrer&quot;&gt;H-1b&lt;/a&gt; visa (it wasn't mentioned in the question), you need to go through the security clearances mentioned in &lt;a href=&quot;https://en.wikipedia.org/wiki/Alien_Flight_Student_Program&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alien Flight Student Program&lt;/a&gt; (official version on &lt;a href=&quot;https://www.tsa.gov/stakeholders/training-and-exercises-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;TSA website&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA has put together the related information (&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Flight-Instructor-Resources/AOPAs-Guide-to-TSAs-Alien-Flight-Training-Citizenship-Validation-Rule/Aliens-and-Non-U-S-Citizens-Seeking-Flight-Training&quot; rel=&quot;nofollow noreferrer&quot;&gt;website&lt;/a&gt;). I also found about &lt;a href=&quot;http://www.theflightschool.com/afsp.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this flight school&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt; which has outlined the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you search on Google about &lt;em&gt;Alien Flight Student Program&lt;/em&gt;, you will find a ton of information.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: &lt;strong&gt;Disclaimer&lt;/strong&gt; I am not advertising any flight school.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-03-16T15:52:28.310" LastActivityDate="2015-07-15T14:02:17.267" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16890" PostTypeId="2" ParentId="16888" CreationDate="2015-07-14T18:49:56.773" Score="3" Body="&lt;p&gt;You will probably need &lt;a href=&quot;http://travel.state.gov/content/visas/english/study-exchange/student.html&quot; rel=&quot;nofollow&quot;&gt;an M-1 visa&lt;/a&gt; for flight training, though you may also be permitted to do flight training on an F series visa (e.g. if it's in conjunction with a college aviation degree program).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not really a TSA matter (aside from the parts relevant to &lt;a href=&quot;https://www.flightschoolcandidates.gov/afsp2/?acct_type=c&amp;amp;section=WN&quot; rel=&quot;nofollow&quot;&gt;the Alien Flight Student Program&lt;/a&gt;), but rather a &lt;a href=&quot;http://travel.state.gov/content/visas/english.html&quot; rel=&quot;nofollow&quot;&gt;State Department matter&lt;/a&gt;. To confirm the specifics and determine which visa type is most appropriate for your planned course of study you should contact the state department (or &lt;a href=&quot;http://travel.state.gov/content/visas/english/general/find-a-u-s--embassy-or-consulate.html&quot; rel=&quot;nofollow&quot;&gt;the US embassy/consulate in your home country&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-14T18:49:56.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16891" PostTypeId="1" AcceptedAnswerId="16900" CreationDate="2015-07-14T19:14:30.387" Score="20" ViewCount="696" Body="&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/16816/how-is-a-type-rating-administered-for-aircraft-that-do-not-comply-with-91-109&quot;&gt;question about being certified to fly aircraft that don't fall under a type rating&lt;/a&gt; got me thinking. For all knowledge possessed by humans there must be a source. If you want to get certified on a Bombardier CRJ narrow-body, you have to be trained by someone who has not only also been rated to fly it, but certified to train on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This process is inherently iterative; someone trained your trainer, and someone else trained your trainer's trainer, and so on until at least a time when there were no aircraft of that specific model. At some point, someone got their approval to fly and teach that model without a single hour of stick time in that specific model of aircraft, because it simply didn't exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft like a Bombardier, the alternate training avenues are obvious; the manufacturer, located in a staunch U.S.-allied nation, will produce training materials and at least fixed cockpit sims, which when coupled with flight time in some other narrow-body T-tail jet, will serve as the basis for certification to fly and ultimately train others on any new Bombardier model. However, this gets tricky when you consider models of aircraft not falling into FAA-defined types, especially single-seaters, and definitely the first one or two of these aircraft to enter civilian hands. Vintage ex-mil planes, especially from non-Allied countries, are the primary example; how did the first civilian Zero owner get certified to fly it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One possibility I thought of for how this could come about is based on the fact that there are a number of pilots/instructors with an extraordinary number of ratings. The current record, IIRC, is over 100 type ratings and/or specific aircraft model certifications. At some point, more training for a pilot like this on any specific airframe becomes redundant; there's nothing the pilot can learn from a CFI that a combination of the pilot's own experience on comparable models and whatever training materials exist for the airframe could provide. A pilot like this would be an obvious choice to take the first flight in some new plane, unique in the U.S. civvie world, but technically he'd still need authorization to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So the question is, is there ever a &quot;tipping point&quot; where a pilot can legally use some combination of his existing qualifications to assert by himself that he has the required knowledge and skill to fly a first-of-its-model plane, for which he does not have an LOA and could not get one through normal channels?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One possible example. Say it's 1992. The Soviet Union has just broken up and the Red Army's military hardware is being auctioned off to the highest bidder. A collector and flight enthusiast in the U.S., who already owns and flies some ex-mil jets like the F-86 Sabre, heads overseas and buys himself an old MiG-17 from the USSR reserve forces in flyable condition; the first one ever to be in private American hands. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, how does he get certified to fly it within FAA-controlled airspace? Does he have to find a former Soviet pilot who can train him, and somehow transfer that Soviet pilot's voucher into an FAA LOA? Is there some high level of instructor certification that allows a CFI to train on airframes the CFI himself is seeing for the first time? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, can the collector himself, given his existing LOAs for closely comparable aircraft including his own Sabre, assert that he is capable of flying the MiG-17 and do so without anyone else having to vouch for that ability? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing I can think of besides the pilot just saying &quot;someone's gotta be the first to learn to fly this thing, and it might as well be me&quot;, is for the FAA to say exactly the same thing, and directly issue some sort of special provisional authorization for the collector to learn the aircraft for himself, hands-on, no CFI. This authorization would naturally contain all sorts of restrictions on when/where he could fly it (if I were the FAA watching someone learn to fly a military jet, I'd point him to the nearest MOA), until he could &lt;em&gt;somehow&lt;/em&gt; demonstrate to &lt;em&gt;someone&lt;/em&gt; that he'd attained mastery of the airframe and have most or all of the restrictions lifted with an LOA. The specifics of how all this would happen, though, escape me.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-16T23:27:17.417" Title="Could you ever legally authorize yourself to fly an aircraft that would require an LOA, based on your other certs?" Tags="&lt;pilot-certification&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16892" PostTypeId="2" ParentId="16869" CreationDate="2015-07-14T20:21:52.740" Score="3" Body="&lt;p&gt;The radar cross section (RCS) of an object does not depend on its size, but on the number and orientation of its edges. Opening weapon bays will break up what was a single surface before into several, and the need to align the doors with airflow will create a &lt;a href=&quot;https://aviation.stackexchange.com/questions/15341/advantages-and-disadvantages-of-planform-alignment&quot;&gt;new edge orientation&lt;/a&gt; which will result in a new reflection spike where none was before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the direction at which the radar is looking at the aircraft and the RCS of the plane with closed doors, the difference is between zero in the direction of the main reflection lobes and several orders of magnitude in the new edge direction, namely sideways.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-14T20:21:52.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16894" PostTypeId="2" ParentId="7437" CreationDate="2015-07-14T22:06:35.710" Score="1" Body="&lt;p&gt;It depends on the airliner design.  If one engine is inside the fuselage tail section and can close side intake scoops and streamline engine bypass cowling, then range will increase as drag is a lot lower with one engine out of the air steam, and the remaining outside engine will have a higher engine rpm, hence higher efficiency using less fuel for the needed thrust. Chances are the needed thrust will be available as engines spool down quite a lot at cruise (oversized to take off). However, the higher thrust will decrease the life of the single cruise engine. Of course, the single cruise engine could be sized to take advantage of this condition to maximize fuel efficiency at normal wear.&lt;/p&gt;&#xA;" OwnerUserId="9374" LastActivityDate="2015-07-14T22:06:35.710" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16895" PostTypeId="1" CreationDate="2015-07-14T22:19:19.407" Score="-7" ViewCount="857" Body="&lt;p&gt;I have been researching about the aviation industry and i have some questions about the leasing and buying procedures and faa ,fcc permissions costs, i would really appreciate your help , thank you&lt;/p&gt;&#xA;" OwnerUserId="9375" LastActivityDate="2015-09-23T18:35:49.023" Title="I want to get as much information i can get to start a new airline who can help me please?" Tags="&lt;faa-regulations&gt;&lt;airliner&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2015-07-14T23:25:32.793" ContentLicense="CC BY-SA 3.0" />
  <row Id="16897" PostTypeId="2" ParentId="16891" CreationDate="2015-07-14T23:22:51.637" Score="8" Body="&lt;p&gt;The original question which you linked to contains a link to the FAA Inspectors Handbook, which covers this scenario as well:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5-1590    TEMPORARY LETTERS OF AUTHORIZATION.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A.    For one‑of‑a kind aircraft, first‑of‑a‑type aircraft,&#xA;  amateur‑built aircraft, practice in a single‑place aircraft, or other&#xA;  special cases, a temporary LOA may be issued. Temporary LOAs may only be issued for a&#xA;  specific purpose and should be for a specified, limited duration. ASIs&#xA;  who receive requests for temporary LOAs for operating experimental&#xA;  aircraft must coordinate with the NPO before issuing them. These LOAs&#xA;  may be required to ensure compliance with the aircraft operating&#xA;  limitations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;B.    Temporary LOAs for the operation of experimental aircraft should&#xA;  not be confused with temporary LOAs for the operation of TC’d&#xA;  aircraft. Section 61.31(b) permits operating TC’d aircraft under&#xA;  limited circumstances. These LOAs are issued in accordance with the&#xA;  guidance in Volume 5, Chapter 9, Section 3.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-07-14T23:22:51.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16898" PostTypeId="1" AcceptedAnswerId="16901" CreationDate="2015-07-14T23:56:08.567" Score="10" ViewCount="760" Body="&lt;p&gt;I have been reading a lot about how altimeters work, and from what I understood, most common altimeters are based of atmospheric pressure to calculate the altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question that I still have though is: &lt;strong&gt;If left stationary at a specific height, would altimeter change the displayed value over time?&lt;/strong&gt; Something tell me there would be slight variation, because air pressure changes almost daily, or am I totally off with this one?&lt;/p&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2015-07-18T13:23:50.067" Title="If left stationary at a specific height, would altimeter change the displayed value over time?" Tags="&lt;altimeter&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16899" PostTypeId="2" ParentId="16895" CreationDate="2015-07-14T23:59:51.647" Score="2" Body="&lt;p&gt;If you were planning your own airline startup, the first thing you would need to ask and answer is &quot;What is my target market&quot;? To answer this question well, you have to look at what the existing aviation industry does, and does not, already provide. Your initial competitive advantage against much larger competitors with economies of scale is going to be the ability to do something that they aren't doing now, and that advantage will be sustainable, thus keeping you in the game longer, if the existing airlines can't or won't do what you will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last big U.S. airline startup to remain successful today, JetBlue, was in 2000, and was started by former Southwest employees and execs to create a similar airline with a few more frills up in the Eastern Seaboard. It took hold after a dramatic decrease in competition in the region following 9/11 and the major airline mergers (Northwest with Delta, Continental with United, TWA with American) and the collapse or absorption of several smaller discount lines like Midwest, America West etc. leaving a vacuum at several major airports in the East that the largest surviving discount carrier, Southwest, didn't (at the time) have the fleet size, regulatory approval or low-cost gate rental arrangements to fill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To start a successful airline, you first have to identify an opportunity like that. That requires in-depth market analysis; how many airlines serve each airport? Where can you go? At what prices? How about nonstops? The information about what flights are available where and at what cost and what amount of rigamarole (stops, layovers) is public and widely available through any travel site. The number of passengers on each flight, and the complete itinerary of each passenger including their ultimate destination, tends to be pretty jealously guarded by airlines to prevent just this kind of data mining by potential competitors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having analyzed where people want to go, how they currently get there and at what prices, you might find an opportunity. People in Lubbock and Waco, Texas, for instance, pretty much depend on regional service to Dallas to connect to a larger flight practically anywhere else. You might identify that people in Waco commonly want to get to St. Louis (for whatever reason) but the only available flights are through either Dallas or Houston, nothing direct. If you can offer a nonstop flight at a similar price (or even beat the layover flights) you have yourself a business opportunity. You'll look across the entire map to find more of these, and put together a set of routes that you're confident you could operate profitably. To determine profitability, you'd need to know both the direct and indirect costs of running the route. Fuel, pilot and flight attendant time are your primary direct costs; everything else, from the cost of the aircraft itself, gate rentals, gate staff, ticketing counters and staff, company ground staff, scheduling and administrative staff, corporate floor space, and your own salary is all overhead. You have to reliably estimate all this to determine the allocated cost of running the route, to determine the breakeven ticket price of an 80% full plane, to see whether that price would compete with the airlines currently serving that airport on a similar route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using these identified potentially profitable opportunities, you craft a business plan; you'll offer direct service on narrow-body jets, between 50-100 people per flight, between these various under-served cities. These facts will help you determine your basic business needs. First, you need an &quot;Air Operator Certificate&quot;. This is actually one of the &lt;em&gt;last&lt;/em&gt; things you actually receive, once you have at least one plane and a plan to fly it for hire along at least one route, with arrangements for ground support in place at your destinations. To get all those things, you need money. So, you take your business plan, including the plans to purchase the aircraft you'll want to run the routes, and take that to banks and potential investors. Depending on the economy at the time, there's typically a lot of startup investment capital available, however the airline industry has been perceived as extremely risky for at least a decade now, so venture capitalists will be extremely skittish about fronting the millions of dollars needed to buy or even lease a few Bombardiers or Embraers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you can pull together the capital you need, you set the plan in motion. You start recruiting pilots with the proper certifications (your flight crewmen will need ATPLs to fly a plane being operated as part of a &quot;commercial airline&quot;; a jet taxi/timeshare business like NetJets can get away with ordinary commercial-level pilots because the business is structured and operated differently), you start hiring ground support and administrative staff, you sign on the dotted line for the plane deliveries, you start making arrangements for bulk fuel purchases at your airports. Eventually all the pieces will fall in to place, your new airline will be issued its AOC and you'll watch your first flight depart the gate with ticketed passengers aboard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then the analysis continues; were your estimates correct? Was there demand for your new nonstop route? Did the price you set and the number of customers you got cover the cost of the flight itself and all the other services you needed to get the passengers onto it? If so, pat yourself on the back and continue flying. If not (much more likely), identify what's off. Are you not getting the fuel price you thought because you're small potatoes for the airport's fueling cartel? Did not enough passengers book? Are the pilots or ground crew costing you more than you thought? Can you take these new numbers into account and increase your ticket prices to cover them, or is the problem that you flew a half-empty plane and need to attract more customers to get the per-trip revenues up to your estimates? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, did you just fly a brand-new plane full of people who paid more than they otherwise would have, on a non-stop no-frills flight on competitively-priced fuel to another airport with minimum support staff, and still lose money? That's what I thought. That's likely because you set up a network of one or two flights a day out of each airport, for which you still needed to rent time at gates and ticketing counters, and adequately man them both visibly and otherwise. You need to identify more routes you can run, even if the gross margins are smaller, because those additional routes with the same ground staff will make the overhead of running any flights to or from that airport less, making the flights profitable because one flight isn't expected to cover the cost of everything there to support it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can't make it work before the investors cut off the funding, then you go bust. You declare Chapter 7, auction off your assets (planes, ground vehicles, gate/counter facility leases) to the highest bidder, and walk away. You won't be the first nor the last airline in history to have done that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual prices charged by airlines to land each plane, rent a gate, etc are public information but vary by airport (and airlines can negotiate on these fees as they represent a lot of business for the airport). The cost of each plane is also easy to find, as are median salaries for various types of transportation workers (as the companies are often public, so are the CBAs between an airline and various unions). This is all just academic number crunching. The hard part is identifying potential flights with enough customer demand to make operating a flight profitable. The usual way airlines have cut in is to compete directly on price, which is part of the reason the airline industry has until very recently been performing so poorly as an investment; upstart discount carriers flying cheaper fleets to cheaper airports in the same cities have completely destroyed the traditional service-oriented business model.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-23T18:35:49.023" LastActivityDate="2015-09-23T18:35:49.023" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16900" PostTypeId="2" ParentId="16891" CreationDate="2015-07-15T00:11:41.327" Score="9" Body="&lt;p&gt;The answer to this, at least for planes that sport big, whirly props, lies next door to the FSIMS, in &lt;a href=&quot;http://fsims.faa.gov/wdocs/orders/8900_2.htm&quot;&gt;FAA Order 8900.2&lt;/a&gt;, the &quot;General Aviation Airman Designee Handbook&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, you'd contact your local CAF wing or the EAA Warbirds division, who'd then put you in touch with an appropriately qualified National Designated Pilot Examiner (NDPE) via the National Designated Pilot Examiner Registry, or NDPER -- between them, you can get checked out on &lt;em&gt;any&lt;/em&gt; reciprocating aircraft, even a Zero, a Bf-109, an Il-2, or a Mosquito.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-type-certificated turbojet aircraft follow the 8900.1 checkout procedures -- a temporary LOA would be issued as Lnafziger pointed out, usually with an EPE (Experimental Pilot Examiner) or NDPE (yes, some of the NDPEs can check you out in jets too) giving you the final &quot;checkride&quot;, based on their qualification in similar types of aircraft (for instance, if you hauled a Su-30MK home from the Sukhoi factory, you'd probably have an ex-F-15 pilot or the likes checking you out on the type).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if it's a UFO (aka something that is not of any extant category or class), then AFS-800 would probably have to step in and send or designate someone.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-07-15T00:11:41.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16901" PostTypeId="2" ParentId="16898" CreationDate="2015-07-15T00:40:39.953" Score="10" Body="&lt;p&gt;You are correct in both regards -- as Terry's comment points out, an undisturbed pressure altimeter's reading (imagine one sitting on a bench outside the local hangar) will change with the local barometric pressure.  TSO'ed &quot;sensitive altimeters&quot;, i.e. ones with a hundreds pointer, not just a thousands, are required to have a knob and window, called a Kollsman window, for setting the local barometric pressure, or standard pressure (29.92) when above the transition altitude (18,000' in the US, check with the local aviation regulator for where you are in the world).  &quot;Glass cockpit&quot; systems have a knob/function for the same job -- whether it be a dedicated knob, or a mode on a multi-function knob.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-07-15T03:33:39.970" LastActivityDate="2015-07-15T03:33:39.970" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16902" PostTypeId="2" ParentId="16862" CreationDate="2015-07-15T00:47:34.910" Score="8" Body="&lt;p&gt;It is the use of composite materials in the aircraft body structure that has enabled larger windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Metals are a crystalline structure that over time tend to fracture along crystal structure defects. Some key areas (e.g. turbine blades in the engine) are actually created by growing a single crystal to obtain higher failure points.  This is not possible over a structure the size of the aircraft frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aircraft is at altitude, it is like a pressurised balloon.  its skin is under tension, and when it on the ground, that tension is removed.  This is like constantly flexing a metal paper clip. The cross sectional area of the aircraft skin that carries this tension is reduced by windows - bigger windows put bigger strain on the airframe structure which tends to concentrate at corners.  making corners rounded helps to spread this stress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The composite materials used in new planes are fibrous in structure. This greatly reduces the risks from the repeated flexing, allowing larger windows (and as the rust risk is reduced, cabin air is allowed to be more moist with also aids in flight comfort of passengers)&lt;/p&gt;&#xA;" OwnerUserId="9378" LastActivityDate="2015-07-15T00:47:34.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16903" PostTypeId="2" ParentId="16881" CreationDate="2015-07-15T04:56:19.190" Score="2" Body="&lt;p&gt;I am certain pilots cannot control galley carts position especially in turbulence. These units are manually controlled by flight attedants and maybe out of control in rough weather if not properly secured.&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-07-15T04:56:19.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16906" PostTypeId="2" ParentId="16898" CreationDate="2015-07-15T06:07:46.550" Score="2" Body="&lt;p&gt;Yes - as noted above, an Aneroid Altimeter will indeed show different altitudes if you come back the next day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and No, a Radar Altimeter will not change its reading as it is measuring the altitude by &quot;listening&quot; to return echos from its transmitter.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2015-07-18T13:23:50.067" LastActivityDate="2015-07-18T13:23:50.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16908" PostTypeId="1" AcceptedAnswerId="16909" CreationDate="2015-07-15T07:34:41.510" Score="8" ViewCount="2962" Body="&lt;p&gt;Reading about aircraft carrier operation turns out that carrier operation relies a lot on catapult and carrier itself turns into wind with high rev on propellers. This generate as high wind speed as possible to make a takeoff easier for fixed wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is in the absense of carrier's own speed and turning into the wind, would fixed-wing carrier-based aircraft be able to takeoff using catapult and its power alone?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="8547" LastEditDate="2015-07-15T10:36:58.720" LastActivityDate="2021-03-15T18:24:45.380" Title="Can carrier-based aircraft takeoff while the carrier is stationary?" Tags="&lt;aircraft-design&gt;&lt;fixed-wing&gt;&lt;aircraft-carrier&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16909" PostTypeId="2" ParentId="16908" CreationDate="2015-07-15T10:36:42.247" Score="3" Body="&lt;p&gt;Aircraft carriers using &lt;a href=&quot;https://en.wikipedia.org/wiki/STOBAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;STOBAR&lt;/a&gt; (the skyramp) always need to maintain a speed of about 55kmph in order for the aircraft on them to take off. This is done to generate enough windspeed on the deck to assist the aircraft to take off. And STOBAR system already hampers the carrying capacity of aircraft, so for takeoff from a STOBAR carrier at rest, a further reduction in takeoff weight of the aircraft would be required to generate enough lift for the aircraft to take off at such low speeds. This reduction in weight would depend on the aircraft carrier and the aircraft as such and might create scenarios where this is entirely not possible.&lt;/p&gt;&#xA;&lt;p&gt;For Aircraft Carriers equipped with &lt;a href=&quot;https://en.wikipedia.org/wiki/CATOBAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;CATOBAR&lt;/a&gt;, the conventional steam piston drive which is used to catapult the aircraft provides approximately 95 MegaJoules of energy to accelerate the aircraft to speeds where it can takeoff safely. Hence the arguments stated about the STOBAR carriers can be sequentially applied to this class as well. But recent &lt;a href=&quot;https://en.wikipedia.org/wiki/Electromagnetic_Aircraft_Launch_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Electromagnetic Aircraft Launch System&lt;/a&gt; provides around 122 MegaJoules of energy to accelerate the aircraft. Given the extra amount of energy available to accelerate the aircraft at higher speeds, it is quite possible that it is going to be easier for the aircraft to take off from a static aircraft carrier equipped with electromagnetic catapults when compared to the aircraft carriers equipped with convention steam piston catapults. But the exact details for the feasibility of this idea would be a matter of national interest and might not be available online.&lt;/p&gt;&#xA;&lt;p&gt;Also, one should not ignore the extra amount of stresses that an aircraft would have to face while taking off from a stationary aircraft carrier as it would have to accelerate to a higher speed at the same available length of the runway and hence this might prove detrimental to the lifetime of the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&lt;p&gt;Under research technologies such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_carriage&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ground Carriers&lt;/a&gt;, if implemented would also assist further in reducing the weight of the aircraft and hence make it easier for the aircraft to take off from carriers at much lower speeds.&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="7532" LastEditDate="2021-03-15T18:24:45.380" LastActivityDate="2021-03-15T18:24:45.380" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16910" PostTypeId="1" AcceptedAnswerId="16916" CreationDate="2015-07-15T12:27:38.747" Score="17" ViewCount="11206" Body="&lt;p&gt;In this &lt;a href=&quot;https://aviation.stackexchange.com/a/16901/5517&quot;&gt;answer&lt;/a&gt; reference was made to &quot;sensitive&quot; and &quot;non-sensitive&quot; altimeters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the definition of each, what are the differences, and why would one be used in preference to the other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;And why isn't it called an &quot;insensitive&quot; altimeter?&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-07-15T22:13:34.743" Title="What is the difference between &quot;sensitive&quot; and &quot;non-sensitive&quot; altimeters?" Tags="&lt;flight-instruments&gt;&lt;terminology&gt;&lt;altimeter&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16911" PostTypeId="1" AcceptedAnswerId="16926" CreationDate="2015-07-15T13:52:17.270" Score="9" ViewCount="1127" Body="&lt;p&gt;The Concorde was anyways a technical marvel of its time, and a status symbol for society. Its fares were well above the rest, &lt;a href=&quot;http://www.samchuiphotos.com/Concorde/ConcordeTripReport2.html&quot; rel=&quot;noreferrer&quot;&gt;costing&lt;/a&gt; USD2999 + taxes for a JFK-LHR journey. But, at the same time there are &lt;a href=&quot;http://www.icmrindia.org/casestudies/catalogue/Business%20Strategy2/Concorde%20Saga.htm&quot; rel=&quot;noreferrer&quot;&gt;reports&lt;/a&gt; that British Airways indeed made $750 million from it, over 27 years:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It was not that Concorde operations made losses. In fact, on an&#xA;  average Concorde made an operating profit of £30-50 million a year&#xA;  for BA. BA reportedly earned £1.75 Billion in revenue for Concorde&#xA;  services against an operating cost of around £1 billion during its 27&#xA;  years of commercial operation (1976-2003).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, what impact did it have on the business of other sub-sonic airliners? Probably, economy class would not have been so much stricken, since its fares were more than 3 times higher. But what was the impact on business class travel of other airlines and airliners, between the destinations served by the Concorde?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="995" LastEditDate="2015-11-19T23:29:02.857" LastActivityDate="2015-11-19T23:29:02.857" Title="What impact did the Concorde have on business of other sub-sonic airliners?" Tags="&lt;commercial-aviation&gt;&lt;aviation-history&gt;&lt;cost&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16912" PostTypeId="2" ParentId="16876" CreationDate="2015-07-15T13:58:56.620" Score="0" Body="&lt;p&gt;Low observable aircraft are designed to emit IR radiation at frequencies that are less useful for sensors and/or better absorbed by the atmosphere.  This is done with coatings.  Some aircraft such as the F-35 also use heat exchangers put some of the heat generated into the fuel supply.  Heat sources such as the radar can be cooled by fuel rather than allowing the heat to escape the the atmosphere.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-07-15T13:58:56.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16913" PostTypeId="1" AcceptedAnswerId="16915" CreationDate="2015-07-15T14:03:06.970" Score="13" ViewCount="12119" Body="&lt;p&gt;There are several instances where we see the landing gear getting stuck before landing. In these kind of situations, can the crew, or one of the pilots, go down to the landing gear area and solve the issue?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="19" LastEditDate="2016-11-03T12:50:26.510" LastActivityDate="2018-12-28T16:39:48.550" Title="If the landing gear is stuck in an airliner, can the crew go down and manually open it?" Tags="&lt;airliner&gt;&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="16915" PostTypeId="2" ParentId="16913" CreationDate="2015-07-15T15:55:38.290" Score="30" Body="&lt;p&gt;On older (WWII-era) large planes, the crew had access to a manual crank to lower the gear if the automatic extension/retraction system (usually a linear actuator powered electrically) failed. I don't know of any that had a gravity-based manual system; I'm sure a few bomber crews would have appreciated something like that after having to crank the handle to get a disabled main gear locked. Here are the manual crank ports for the B-17, on the forward bomb bay bulkhead with red arrows indicating the direction to crank:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WqjDY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-17 had a retractable tail gear as well, so there was a third manual crank in the tunnel to the rear gunner's position (but if there were multiple gear failures, the main gear would be the priority).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On more modern airliners with hydraulic extension/retraction, manually cranking the gear into place isn't as much of an option (especially since any access to a crank linkage would be in either the passenger cabin or the cargo hold). For these aircraft, the gear are designed with a &quot;manual extension&quot; or &quot;gravity release&quot;. This basically disconnects the gear strut from its uplocks and the hydraulic cylinder, allowing gravity to pull the gear down and then momentum (or a spring mechanism) will engage the downlocks. Here is a diagram of the 737's manual gear panel on the right-hand wall of the flight deck:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/oAgRb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 has a manual nose gear extension system in the avionics compartment below the first-class cabin. The 747's main gear are much more complex, but it is still possible to let gravity pull them into place, by using a set of &quot;alternate gear extension&quot; switches on the overhead panel to release each gear from the hydraulics and uplocks:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jBdPK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't always work; a Virgin Atlantic 747 pilot was forced to make an emergency landing with the outboard right main gear stuck in a half-extended position:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wqpbR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/SdrDJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-15T16:54:26.660" LastActivityDate="2015-07-15T16:54:26.660" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16916" PostTypeId="2" ParentId="16910" CreationDate="2015-07-15T16:09:31.297" Score="18" Body="&lt;p&gt;All altimeters are &quot;sensitive&quot; to some extent (an &quot;insensitive&quot; altimeter would be one where the internal pressure-sensing mechanism has failed: the pointer wouldn't ever move).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the FAA calls a &quot;sensitive altimeter&quot; is simply &lt;em&gt;more sensitive&lt;/em&gt; than a regular (now often called non-sensitive) one: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Non-Sensitive&lt;/strong&gt; altimeters have a 1000-foot scale (200-foot tick marks) as their most precise display.  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Sensitive&lt;/strong&gt; altimeters have a 100-foot scale (20-foot tick marks) as their most precise display.  &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The sensitive altimeter in &quot;glass cockpit&quot; displays go even further, often having 1-foot resolution on a digital read-out.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Let's look at some (analog) examples:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Non-Sensitive Altimeter, not adjustable for barometric pressure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/07Lok.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/07Lok.jpg&quot; alt=&quot;Non-Sensitive non-Baro-Adjustable&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;This altimeter is similar to what you'd find on an old Piper Cub: The scale is marked in &lt;em&gt;thousands&lt;/em&gt; of feet, with ticks every 200 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This altimeter is not adjustable for &quot;barometric pressure&quot;, but it is adjustable: The little knob on the bottom rotates the face of the altimeter. Put field elevation under the needle before you take off and it should be a reasonable approximation of your current altitude for the duration &amp;amp; distance of a typical Piper Cub flight.&lt;br&gt;&#xA;These altimeters can only be &quot;set&quot; on the ground, because you need to know your elevation to set the position of the face or needle.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Non-Sensitive Altimeter, adjustable for barometric pressure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QEkWd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QEkWdm.jpg&quot; alt=&quot;Non-Sensitive Baro-Adjustable&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;These show up from time to time: It's a non-sensitive altimeter (same scale markings we saw above), but it's adjustable for barometric pressure. The Kollsman window on this one is marked in inches of mercury.&lt;br&gt;&#xA;When you turn the knob on this altimeter the needle moves and the barometric pressure that corresponds to &quot;zero feet&quot; shows up in the Kollsman window. This makes it easier to read than the previous example, and easier to reset in flight based on radio information: You can set the local barometric pressure (QNH) in the Kollsman window and get your current altitude without having to be on the ground at a known elevation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Sensitive altimeter, &lt;em&gt;not&lt;/em&gt; adjustable for barometric pressure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mCyxn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mCyxnm.jpg&quot; alt=&quot;Sensitive non-baro-adjustable&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;In this sensitive altimeter you can see that there is a 100 foot scale (large pointer), and a 1000-foot scale (small pointer).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a bit of an unusual example: It's a sensitive altimeter that is &lt;strong&gt;&lt;em&gt;NOT&lt;/em&gt;&lt;/strong&gt; adjustable for barometric pressure (the knob simply adjusts the position of the pointers, and you set it to field elevation like you would with our first example. It can't be easily reset in flight as you need to know your current altitude to reset the altimeter correctly.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Sensitive Altimeter, adjustable for barometric pressure&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2fvUr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2fvUrm.jpg&quot; alt=&quot;Sensitive Baro-Adjustable&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;This the altimeter most pilots are used to seeing in a &quot;steam gauge&quot; panel: It is a sensitive altimeter (note the 100-foot scale pointer), and it is adjustable for barometric pressure (note the Kollsman window, marked in millibars in this example). This is the type of altimeter required for IFR flight.&lt;br&gt;&#xA;This one happens to include 3 pointers (100-foot, 1,000-foot, and 10,000 foot), because it's calibrated to 20,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As with most aviation products there is a Technical Standard Order (TSO) behind altimeters which would get into all the specific details of the differences.&lt;br&gt;&#xA;For sensitive altimeters it's TSO C10 (I believe C10b is current).&lt;br&gt;&#xA;I'm not sure if there's one for a non-sensitive altimeter.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-07-15T22:13:34.743" LastActivityDate="2015-07-15T22:13:34.743" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16917" PostTypeId="2" ParentId="16913" CreationDate="2015-07-15T16:48:54.257" Score="10" Body="&lt;p&gt;No, there isn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think any aircraft has access door from inside to the main wheel well. Some aircraft do have access hatch via the nose wheel well, but since the wheel well is unpressurised and the cabin is pressurised, it would not be possible to open the hatch in flight and even if it was possible (after depressurising the aircraft at low altitude), trying to do anything there with the gear door open (which it would have to be obviously) would be extremely dangerous and the chance of success would not be big, because a man has much less strength than the hydraulics that already tried to get the gear out and failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any aircraft with retractable landing gear is required to have an alternate extension mechanism that can be used to extend it if the primary system operating the gear fails, which was already well explained by &lt;a href=&quot;https://aviation.stackexchange.com/a/16915/524&quot;&gt;KeithS&lt;/a&gt;. But when that also fails, there is no way to access the gear to attempt to unjam it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are designed with all sorts of emergencies in mind and even landing with partial gear is not a big deal. Sure, it will do some damage to the plane, possibly even to the point that it's not economical to try to fix it, but that's what insurance is for, and risk of injury is minimal. For recent examples of gear mishaps see:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=410e3b5a&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jetblue A320 at Los Angeles on Sep 21st 2005, nosewheel tilted 90 degrees for landing&lt;/a&gt; and &lt;a href=&quot;http://avherald.com/h?article=43b46cee&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vueling A320 at Sevilla on Apr 20th 2011, nose wheels tilted 90 degrees on landing&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=46380ff0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wizz A320 at Rome on Jun 8th 2013, left main gear did not extend&lt;/a&gt; and &lt;a href=&quot;http://avherald.com/h?article=469338e0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alitalia A320 at Rome on Sep 29th 2013, right main gear did not extend&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=4456bd6b&quot; rel=&quot;nofollow noreferrer&quot;&gt;LOT B763 at Warsaw on Nov 1st 2011, forced gear up landing&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All occupants of those aircraft were OK, only 3 minor injuries in one of them from the evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also in some cases the gear fails when the aircraft touches down, so nobody could do anything about it, because there is no indication it's going to happen beforehand. If it's just that, the risk of injury is still small. Example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=47d11b69&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ariana Afghan B734 at Kabul on Nov 7th 2014, gear collapse on landing&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;which also ended without injury.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-07-15T16:48:54.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16918" PostTypeId="2" ParentId="7757" CreationDate="2015-07-15T20:03:18.840" Score="2" Body="&lt;p&gt;Not with enough time to react. In clear weather, the average ability to spot another plane in the air unaided (no cue as to relative bearing or altitude) is about 7-10 miles, and as few as 3 miles for small craft. Professional military pilots with exceptional eyesight can improve on that but even they rely on their own radar, their wingmen and AWACS to alert them of other traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let's assume the best, and say you could spot a small craft like a fighter at 10 miles, and notice when it had fired an AMRAAM missile. By the time an AMRAAM's motor has cut out, it is travelling Mach 4, about 3,045 mph. That's 0.845 miles per second; it would take just under 12 seconds for the missile to reach you, fifteen at most accounting for the arched flight path and time to accelerate. So, assuming you knew the missile had been launched, you have fifteen seconds max to locate, track and maneuver to avoid it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That assumption that you even see the missile launch is a pretty big one; U.S. fighter pilots have excellent vision, usually the 95th percentile or better of the U.S. population for visual acuity, and still rely on a battery of detectors to notify them of radar sources including from radar-guided missiles and their shooting aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the big ones is the Radar Warning Receiver or RWR. Most civilian aircraft do not have this system but it actually would not be out of the question to install it on a commercial airliner (the AN/APR-39 RWR system costs the military about \$170k per plane; that's a drop in the bucket to a Boeing 777's \$320 &lt;em&gt;million&lt;/em&gt; sticker price); it is independent of the aircraft's own radar systems, and consists of four radar detectors to provide localization direction and strength, a computer processor to identify the likely aggressor type based on the radar pulses detected, and a flight instrument display to show the results to the pilot. With such a system installed, the pilot would get a warning of a radar lock and incoming radar-homing missile including relative direction, even if the missile were beyond visual range. Upgrade to a full Missile Approach Warning system and you can get missile speed, distance, relative altitude and time to intercept information. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot would use this information to place the weapon &quot;on the beam&quot; (directly to his left or right) which forces the missile to use up its energy turning to a constantly changing intercept point. Then, as the missile closes in, the pilot would execute a max-G turn in the direction of the missile, forcing it to turn even tighter to intercept, hopefully tighter than the missile is able to turn thus falling behind the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UumrV.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed of the target aircraft is not the problem; a fighter jet cannot execute the necessary turning maneuver at high speed anyway because it would overload the airframe (and pilot). An F-16's &quot;corner airspeed&quot; is around 320 knots, easily within an airliner's performance envelope. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the airliner is not capable of is a 9 G-force turn. Normal flight maneuvers for an airliner attempt to maintain 1G. The airframe is only proof-tested to a &quot;load factor&quot; of 1.25 times its MTOW, while its theoretical maximum loading factor based on design specs is only 1.5x MTOW. So even empty of passengers and cargo and light on fuel, the maximum G-load the airframe would likely withstand without the wings collapsing would be somewhere in the 2-3G range. Missiles can easily pull 30-40 Gs, so even given that they're moving much faster (and therefore the forces needed to turn them within a particular radius are higher), an airliner stands little chance of evading a missile unless it was poorly aimed and at too close a range to correct itself. In that situation the missile would have missed before the pilot knew it was there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, overall, the only reason a pilot would need to be able to detect an incoming missile is so he knows when to pray. Without flares or chaff to help spoof the missile (which add weight that would only be used once in 50 blue moons) the chances of evasion are slim to none, and even with countermeasures, a target that big moving that slow needs a &lt;em&gt;big&lt;/em&gt; distraction:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/27oj9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-15T22:22:16.640" LastActivityDate="2015-07-15T22:22:16.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16920" PostTypeId="1" AcceptedAnswerId="16921" CreationDate="2015-07-15T23:10:47.493" Score="6" ViewCount="2285" Body="&lt;p&gt;I've been thinking of getting an ultralight as a low cost way to pursue flying.  And I've been wondering, when my instructor finally signs me off for a solo flight, am I allowed to do that in an &lt;a href=&quot;https://en.wikipedia.org/wiki/Ultralight_aviation&quot; rel=&quot;nofollow&quot;&gt;ultralight&lt;/a&gt;?  And, if so, is there equipment I would be required to have that isn't standard on an ultralight?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="572" LastEditDate="2015-07-16T06:33:07.417" LastActivityDate="2015-07-16T15:30:41.860" Title="Can you do your PPL solo time in an ultralight?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;ppl&gt;&lt;ultralight&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16921" PostTypeId="2" ParentId="16920" CreationDate="2015-07-16T01:06:31.730" Score="6" Body="&lt;p&gt;Nope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your solo time must be done &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1109&quot; rel=&quot;nofollow&quot;&gt;in the category and class of aircraft for which you are seeking a pilot certificate&lt;/a&gt; (the FAA doesn't come out and say it in those words, but that's what the &quot;aeronautical experience&quot; requirements basically boil down to). You must also pass a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_187&quot; rel=&quot;nofollow&quot;&gt;pre-solo knowledge exam&lt;/a&gt; and receive instruction in the particular make and model of aircraft you will be solo-ing in (the second of which is impossible in an ultralight: You cannot receive dual instruction in that aircraft as by regulation it can only have one seat).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As you don't need a pilot certificate to fly an ultralight you could just get one, get some basic instruction on flying it (from someone who has flown them before), and go fly. &lt;a href=&quot;http://www.beliteaircraft.com&quot; rel=&quot;nofollow&quot;&gt;Some ultralights are pretty fine basic aircraft&lt;/a&gt; thanks to modern materials and construction techniques.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your private pilot training &amp;amp; solo experience would be helpful in flying certain types of ultralight aircraft, but it's not required as long as you abide by the regulations applicable to ultralights.&lt;br&gt;&#xA;Similarly experience in the more &quot;airplane-like&quot; ultralights may help you out in the rest of your private pilot training, but that experience isn't required (and not really &quot;loggable&quot; toward your training, through you can put it in your logbook if you wish -- just log the time as &quot;Ultralight Flying&quot; or something similar.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-07-16T15:30:41.860" LastActivityDate="2015-07-16T15:30:41.860" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16922" PostTypeId="2" ParentId="16911" CreationDate="2015-07-16T05:01:31.657" Score="3" Body="&lt;p&gt;As told, Concorde is one of the technical marvels of man. It wouldn't have large impact on economy but, it definitely had a huge impact on business class. Concorde would take less time than the subsonic flights, the person choosing business class would as well choose Concorde for the same destination because TIME is one of the major factor. Concorde travels much faster than subsonic.&lt;/p&gt;&#xA;" OwnerUserId="9397" LastActivityDate="2015-07-16T05:01:31.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16923" PostTypeId="2" ParentId="16784" CreationDate="2015-07-16T05:21:10.530" Score="-2" Body="&lt;p&gt;They use the concept of VTOL thats vertical Take off and Landing. &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow&quot;&gt;Click here to know more about VTOL&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the efficiency, well I think no one can give a 100% perfect information on this because, we do not know the fuel used, the engineering behind the structure. There are a lot of factors affecting efficiency like :&#xA;Materials, Fuel, Type of Engine, Weight etc. So aerodynamics alone cannot judge the efficiency of the aerovehicle. &#xA;Thanks! &lt;/p&gt;&#xA;" OwnerUserId="9397" LastActivityDate="2015-07-16T05:21:10.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16924" PostTypeId="1" AcceptedAnswerId="16928" CreationDate="2015-07-16T06:57:00.570" Score="13" ViewCount="19590" Body="&lt;p&gt;I have seen some military jets have a needle-like structure at the nose and some others do not have that. Lockheed SR-71 Blackbirds have that structure and Lockheed Martin F-22 Raptors do not, why so?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Aym3G.jpg&quot; alt=&quot;SR71Nose&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.aviationexplorer.com/sr-71_facts.htm&quot; rel=&quot;noreferrer&quot;&gt;www.aviationexplorer.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/4/46/Lockheed_Martin_F-22A_Raptor_JSOH.jpg&quot; alt=&quot;F22&quot;&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/4/46/Lockheed_Martin_F-22A_Raptor_JSOH.jpg&quot; rel=&quot;noreferrer&quot;&gt;www.wikipedia.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="8094" LastEditorUserId="1696" LastEditDate="2018-04-17T15:23:50.453" LastActivityDate="2018-07-19T02:41:09.223" Title="Why do some military jets have needle-like structures at the nose and others don't?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16926" PostTypeId="2" ParentId="16911" CreationDate="2015-07-16T08:56:15.423" Score="8" Body="&lt;p&gt;A few thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The British Airways Concordes only operated &lt;a href=&quot;http://www.concordesst.com/history/destinations.html&quot;&gt;scheduled&lt;/a&gt; on the London Heathrow- New York JFK route. This implies this is the route under the most competition. There has been enough pressure on this route even after the demise of the Concorde for several companies (as well as BA) to try business-only services on this route.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By experience, changing flights is never quick in the US since you need to go through customs and add time margin to ensure you make the connection (Think three hours connection time on the ground). I think even before the current security state you'd rather have taken a direct flight than change from a Concorde to a domestic flight if possible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I don't think the charter destinations would have caused much impact on other airline operations. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-07-16T08:56:15.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16927" PostTypeId="1" CreationDate="2015-07-16T09:24:36.043" Score="4" ViewCount="7353" Body="&lt;p&gt;As I understand, you trim to reduce the effort needed to maintain the stick in the right position. Thus, you may reach steady flight before moving the trimming wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fly-by-wire aircraft (to fix things, let's consider an A320), there is no such effort to maintain as you use sidesticks. Moreover the elevator may move almost constantly (and thus always apply some effort) to compensate turbulence (&lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire#Automatic_stability_systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;enhance stability feature&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/15268/how-does-trim-work-on-an-a320/15279#15279&quot;&gt;this question&lt;/a&gt;, I understand that trim is achieved by moving the stabilizator and that in normal law it is done by the computer (we actually &lt;a href=&quot;https://www.youtube.com/watch?v=jYh5M89BDUo&amp;amp;t=145&quot; rel=&quot;nofollow noreferrer&quot;&gt;see the trim wheel moving alone&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question comes in several parts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In flight in normal law, how and when does the computer decide it must trim the plane? &lt;/li&gt;&#xA;&lt;li&gt;What does it take into account to trim the plane (speed? flaps configuration? average position of the elevators for the last few seconds? a mix of all? I guess average position of the elevator in a sliding time window is enough)&lt;/li&gt;&#xA;&lt;li&gt;Does it anticipate the trim (e.g. trim before or while changing the flaps configuration)?&lt;/li&gt;&#xA;&lt;li&gt;What happen on the ground? For example during the take off roll, I don't think there is enough data to feed an auto-trim system, but I may be mistaken.&lt;/li&gt;&#xA;&lt;li&gt;What happen if not in normal law (I guess auto-trim would be one of the feature unavailable in alternate law)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;EDIT: althought the question may seem similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/15268/how-does-trim-work-on-an-a320&quot;&gt;this one&lt;/a&gt;, it differs as my question address the decision process used by the auto-trim system to command the flight control surface, and not the flight control surface itself (the use of stabilisator as trim in the A320)&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-19T19:30:20.143" Title="How does auto-trim work on fly-by-wire aircraft?" Tags="&lt;airbus-a320&gt;&lt;fly-by-wire&gt;&lt;trim&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16928" PostTypeId="2" ParentId="16924" CreationDate="2015-07-16T09:51:30.787" Score="7" Body="&lt;p&gt;What you see on the SR-71 is an Alpha-Beta probe, with a pitot tube branching off the side of it. The nose cone of the SR-71 (and its variants) were changeable depending on its loadout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the A12 Configuration:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The sharply tapered nose section was pressurized and contained navigational and communications equipment, a&#xA;  remote compass transmitter, periscope optics, air inlet computer and angle transducer, and other radio equipment.&#xA;  A combination pitot-static and alpha-beta probe was installed at the forward tip to capture airspeed and altitude data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;About the SR-71 versatility&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The SR-71 also served as a testbed for an Optical Air Data System (OADS), a fiber optic device using laser&#xA;  technology to replace the pitot tube (airspeed probe) on high-performance aircraft. It used laser light instead of air&#xA;  pressure to produce airspeed and attitude reference data such as angle of attack and sideslip normally obtained with&#xA;  small tubes and vanes extending into the air stream or from tubes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Both sources above: &lt;a href=&quot;http://enu.kz/repository/2009/AIAA-2009-1522.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Design and Development of the Blackbird&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F22 serves quite a different purpose to the variants of the Blackbird, and thus probably has less need for sensitive sensor equipment of the SR-71. It still has a pitot tube which can be seen in the photo you posted&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/obuzb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it, no doubt gets other avionic information from a traditional pitot-static system rather than rely on an alpha-beta probe as the Blackbird did.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="3386" LastEditDate="2018-07-19T02:41:09.223" LastActivityDate="2018-07-19T02:41:09.223" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="16929" PostTypeId="2" ParentId="16927" CreationDate="2015-07-16T10:22:59.650" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;In fly-by-wire aircraft (to fix things, let's consider an A320), there is no such effort to maintain as you use sidesticks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Let's be clear: there is no such effort on the pilot side, but the forces on the surfaces are still there and are taken care of by the electro-hydraulic actuators.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;In flight in normal law, how and when does the computer decide it must trim the plane? &lt;/li&gt;&#xA;  &lt;li&gt;What does it take into account to trim the plane?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I will answer these two together. And let's remember what written above: the actuators are taking care of the control surfaces loads, this means that part of the actuator authority is being used to control a static load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an ideal situation all the authority (coming from hydraulic pressure or coil current) can be dedicated to control transients: gusts, configuration changes, turn entering, turn leaving. If you are allocating part of this authority to keep level flight, a gust (for example) that otherwise would have been easily compensated for, will lead to a momentarily loss of coordination, reducing the comfort of the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is what (mostly) you use to trim the aircraft: if your actuator is constantly (or on average over several seconds) applying a certain force in a certain direction, the system will use the trim functionality to remove said force while not altering the flight equilibrium.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Does it anticipate the trim?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have no public reference for this.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;What happen on the ground?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Usually you leave the aircraft with no trim.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;What happen if not in normal law (I guess auto-trim would be one of the feature unavailable in alternate law)?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unless you are outside of normal law for actuator-related issues (power/hydraulic losses, for example) I see no reason why trimming would be unavailable, all that is required for trimming, as said above, is the average load on the actuators and trimming actuation capabilities.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-07-16T10:22:59.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16931" PostTypeId="1" AcceptedAnswerId="16936" CreationDate="2015-07-16T12:06:02.347" Score="12" ViewCount="2030" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1153&quot;&gt;FAR 61.153(d)&lt;/a&gt;, a pilot may use a foreign commercial or ATP certificate as a prerequisite for getting a US ATP. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To do so, an applicant must:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Meet at least one of the following requirements:&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  (3) Holds either a foreign airline transport pilot license with &lt;strong&gt;instrument privileges&lt;/strong&gt;, or a foreign commercial pilot license with an &lt;strong&gt;instrument rating&lt;/strong&gt;, that... &lt;sub&gt;(emphasis added)&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What's the difference between &quot;instrument privileges&quot; and &quot;Instrument rating&quot;?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-07-16T15:13:30.637" LastActivityDate="2015-07-16T16:58:35.397" Title="What is the difference between instrument privileges and instrument rating?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16932" PostTypeId="1" AcceptedAnswerId="16934" CreationDate="2015-07-16T13:38:53.297" Score="7" ViewCount="1072" Body="&lt;p&gt;Airbus' &lt;a href=&quot;http://www.highflyer.airbus-group.com/04_2013_efan_and_ethrust.html&quot;&gt;own (early) page&lt;/a&gt; with technical data about the e-Fan provides some information about the batteries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can, for instance, be calculated that they hold approx. 19kWh of energy if you accept a somewhat simplistic calculation by multiplying number of cells (120) with capacity (40A ) and voltage (4V).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I can't find is information about the weight of these batteries. Is this information available somewhere or can it be reasonably estimated?&lt;/p&gt;&#xA;" OwnerUserId="2176" LastActivityDate="2015-07-17T13:19:08.563" Title="What is the weight of the batteries on the e-Fan?" Tags="&lt;e-fan&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16933" PostTypeId="2" ParentId="16932" CreationDate="2015-07-16T14:04:16.873" Score="6" Body="&lt;p&gt;Slightly adjusting your energy estimate (3.6V × 40A × 120 Cells = 17280Wh vs original 19000 Wh), taking an &lt;a href=&quot;http://batteryuniversity.com/learn/article/whats_the_best_battery&quot; rel=&quot;nofollow&quot;&gt;energy density&lt;/a&gt; of 125Wh/kg for a high quality battery, it can be estimated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{17280}{125}=138\text{kg}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which I think sounds reasonable for a plane with a empty weight of around 500kg.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-17T13:19:08.563" LastActivityDate="2015-07-17T13:19:08.563" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16934" PostTypeId="2" ParentId="16932" CreationDate="2015-07-16T14:04:29.020" Score="8" Body="&lt;p&gt;The weight of the battery is &lt;a href=&quot;http://aviationweek.com/farnborough-2014/airbus-enters-e-plane-light-aircraft-market&quot; rel=&quot;nofollow&quot;&gt;mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Power is provided by 127 kg. of 250-volt lithium-ion polymer batteries&#xA;  from Kokam in South Korea built into the wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A slightly different weight is &lt;a href=&quot;http://insideevs.com/eads-debuts-electric-e-fan-airplane-at-2013-paris-air-show-wvideo/&quot; rel=&quot;nofollow&quot;&gt;specified here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... E-Fan has two lithium-polymer battery packs weighing 65 kg each.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I could not find which Kokam battery is being used on the e-fan, but &lt;a href=&quot;http://www.cleancarb.com/index.php?option=com_content&amp;amp;view=category&amp;amp;id=38&amp;amp;layout=blog&amp;amp;Itemid=57&quot; rel=&quot;nofollow&quot;&gt;this page has specifications&lt;/a&gt; for all of their batteries.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="9276" LastEditDate="2015-07-16T16:04:19.630" LastActivityDate="2015-07-16T16:04:19.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16935" PostTypeId="1" AcceptedAnswerId="16937" CreationDate="2015-07-16T15:23:54.667" Score="20" ViewCount="4956" Body="&lt;p&gt;Living closer to a Sikorsky factory, I can attest that modern civilian (and military) helicopters are quite noisy. In any case, they are considerably louder than light aircraft, turboprops, and even some jetliners. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has resulted in helicopters being banned from approach and landing in some jurisdictions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems though, that the techniques for sound mitigation of helicopters have been known since at least the 1970s (&lt;a href=&quot;https://en.wikipedia.org/wiki/Hughes_OH-6_Cayuse#.22The_Quiet_One.22&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Quiet One&lt;/a&gt;) let alone the stealth helicopters used in the Bin Laden raid. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is,  part of the solution appears to be to use more rotor blades while decreasing the speed of the rotors. There are also modifications to the tips of the rotor blades that while they may be classified, could be deduced and reverse engineered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are helicopters so loud and why aren't contemporary helicopters quieter given what we know and how far we've come in materials sciences and aviation design? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is a question of economics (quieter == less economic) or politics (national security prevents the use of sound-mitigating technology) or something else?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="11215" LastEditDate="2019-07-29T19:17:46.253" LastActivityDate="2019-07-29T19:17:46.253" Title="Why aren't modern helicopters quieter?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;noise&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16936" PostTypeId="2" ParentId="16931" CreationDate="2015-07-16T15:33:14.070" Score="12" Body="&lt;p&gt;The short answer is that the privileges are what the rating confers, and there are ways to get those privileges other than having the rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A commercial pilot licensee in most jurisdictions that follow ICAO certification guidelines may fly small planes for hire, doing service as a courier, air taxi, crop duster, etc. These do not necessarily require flying in IMC or in Class A airspace, and so a CPL holder must also have a separate &quot;instrument rating certification&quot; in order to fly IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATPL licensees fly in Class A as a matter of course, and that also often requires ascending and descending through the cloud ceiling which is IMC by definition. Therefore, the requirements for an ATPL in ICAO-compliant jurisdictions inherently include those required for the &quot;instrument rating&quot; applied separately to lower certification levels (private/commercial), and the resulting license for an airline pilot confers the same &quot;instrument privileges&quot; that the rating would. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus the difference in terminology; an ATPL holder in another country has &quot;instrument privileges&quot; as a consequence of his basic license and so does not need a specific &quot;instrument rating&quot;. The same is not true for CPLs and so the law specifically requires the instrument rating as a prereq for a foreign CPL seeking an FAA ATPL.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-16T16:49:07.637" LastActivityDate="2015-07-16T16:49:07.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16937" PostTypeId="2" ParentId="16935" CreationDate="2015-07-16T16:37:52.997" Score="18" Body="&lt;p&gt;It's an R&amp;amp;D and therefore ultimately a cost-benefits decision. Quieting techniques for helicopters aren't as simple as &quot;hush kits&quot; for fixed-wings, because the engines and rotors are a much more integral part of the entire airframe. So, to incorporate these features into a civilian helicopter is a much more involved process than swapping blades on a turboprop or putting hush rings on the exhausts of older airliner engines. Changing the physical properties of the rotors (lift, induced drag, moment of inertia) requires compensating changes in the engine; shorter blades reduces lift requiring higher RPM, more blades increases MOI requiring more torque, etc. Those engine changes will in turn require changes to tail rotor characteristics, and may also require frame and body tweaks, etc etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most helicopters in civilian use today, like the Bell 200-series, Sikorsky S-70 family, Dauphin etc are Vietnam-era designs, almost unchanged save for a few minor tweaks along the way like incremental engine improvements or new avionics systems. They're still being built and flown because they &lt;em&gt;work&lt;/em&gt;; take the rigorous proving tests required of any aviation system and the maintenance and inspection requirements of fixed wing aircraft, and add an additional level of caution for the inherent instability and lack of fail-safes in the design of a rotary-wing aircraft, and you'll have some idea of what it takes to get a new helicopter vetted for GA use. If the helicopter's engine cuts out or throws a prop blade, you can't just glide down to the ground the same way as a fixed wing. So, any changes you make to a basic, proven design would be subject to extreme skepticism and testing by both aviation regulators and owners, to say nothing of starting from scratch. This decreases initial sales of a new model in the civilian market, increasing the payback period of your R&amp;amp;D to develop this new design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, in part due to this hesitance by GA to adopt new chopper designs, the funding availability to research and develop any new civilian helicopter design is dwarfed by military interests. As mentioned, practically every design you see in the skies today has a military pedigree and was designed primarily for that purpose, then civilianized for GA use (a notable exception being the Eurocopter Dauphin 2 which was established in the private and law enforcement sectors before militaries took a look). As a result, a lot of the newest stealth technologies available for helicopters, including noise reduction, are heavily classified. For instance, the modifications to the UH-60s used in the Bin Laden raid; civilians really only know that stealth Blackhawks exist, as what they look like and their performance/noise characteristics are all still top secret. That hasn't stopped the human imagination; artist impressions including the concept art for &lt;em&gt;Zero Dark Thirty&lt;/em&gt; abound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, the civilian quiet-copter technologies that aren't classified, like Eurocopter's &quot;Blue Edge&quot; blade design, are mostly protected by international patent. Bell or Sikorsky can't just reverse-engineer the Blue Edge blade and stick it on their choppers. An independently-developed design must be different enough to be patentable, which probably means it will be more complex, and complexity is a bad word in aviation because it means increased probability of system failure or operator error. The other avenues would be to either license Blue Edge from Eurocopter (increasing the cost of a Bell or Sikorsky Blue Edge-equipped model) or wait 15-20 years until the patent expires (further delaying widespread adoption of the technology beyond one brand).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-20T22:25:25.423" LastActivityDate="2015-07-20T22:25:25.423" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16938" PostTypeId="2" ParentId="16931" CreationDate="2015-07-16T16:58:35.397" Score="5" Body="&lt;p&gt;This arises from a difference in how instrument privileges are granted by the FAA.  Private and commercial ratings do not include instrument privileges but the ATP rating does.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that for a commercial pilot to have instrument privileges the pilot must also have an instrument rating.  To apply for an ATP rating the pilot must have instrument privileges (from an instrument rating) and once the ATP is passed, the pilot no longer has an instrument rating, just an ATP rating.  The ATP rating itself grants instrument privileges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wording in the regs you post account for this.  The applicant must have instrument privileges and this can either be from a foreign commercial+instrument rating or just a foreign ATP rating (that grants instrument privileges).  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Instrument privileges allow you do instrument things and an instrument rating is something that confers instrument privileges.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-07-16T16:58:35.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16939" PostTypeId="2" ParentId="16793" CreationDate="2015-07-16T19:32:25.337" Score="4" Body="&lt;p&gt;The short answer is to use color in some way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find anything very detailed on this: there's plenty of general checklist information out there from the FAA, NASA, universities and so on, but nothing that goes into specific details on how to use colors, fonts or the other things that you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is &lt;a href=&quot;http://lessonslearned.faa.gov/Northwest255/VNTSC%20Rpt%20DTO-VNTSC-FAA-91-7.pdf&quot; rel=&quot;nofollow&quot;&gt;an FAA report&lt;/a&gt; called &lt;em&gt;The Use and Design of Flightcrew Checklists and Manuals&lt;/em&gt; that was part of the response to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northwest_Airlines_Flight_255&quot; rel=&quot;nofollow&quot;&gt;Northwest 255 crash&lt;/a&gt;. Unfortunately it's from 1991 so some content is already dated, and it's aimed at part 121 and 135 operators with multiple crew members, but it's an interesting report anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Their main recommendation on memory items was simply to reduce them as much as possible because memory is very unreliable compared to checklists, but again that's in the context of multi-member crews. As for design, layout, formatting etc., they did make some specific recommendations (see section 4.1 and Appendix A) and the most applicable one to your question seems to be the use of color-coding. They strongly recommended the use of color as a general method, e.g. headings in yellow for &quot;abnormal&quot; items and in red for &quot;emergency&quot; items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the report says that at that time (1991) airlines resisted using color because of the costs of printing, but today it &lt;a href=&quot;http://www.google.com/images?q=aircraft%20checklists&quot; rel=&quot;nofollow&quot;&gt;seems to be the generally accepted way&lt;/a&gt; to highlight critical checklists and items. However, each checklist provider has their own approach to coloring headers, text, blocks or even entire pages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think there's any such thing as a standard 'style guide' for checklists, so if you're making your own then you can obviously do whatever you want that works for you. But the 1991 report noted that most checklist problems were caused by missing or inaccurate items, so make sure you get the content right before you break out your paintbrushes :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-16T19:32:25.337" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16940" PostTypeId="1" AcceptedAnswerId="16941" CreationDate="2015-07-16T19:34:02.623" Score="8" ViewCount="783" Body="&lt;p&gt;This question was originally going to be &quot;Is it possible to earn an ATPL without also ending up with at least one airliner type rating?&quot;, but I thought I'd broaden it just a bit (hopefully not too broad).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Requirements for an ATPL in the United States include 1,500 hours total flight time with several minimums in various special conditions and as PIC, &quot;applicable to the aircraft category and class&quot;. My question is basically, &quot;what is the definition of 'applicable'?&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, it is theoretically possible, and even useful, to obtain an ATPL in the ASEL class (so the answer to my original question is &quot;yes&quot;; you can earn the FAA's highest certification level without being signed off on anything close to the type of aircraft Southwest or Delta have in their fleet). You could get that license and fly Cessna singles for Ravn Alaska (formerly &quot;Era Alaska&quot; of Discovery Channel fame) or any of the other bush airlines around the country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, that represents a lot of flight time before you can even sit the written tests and fly the checkride; 1,500 hours total (250 as PIC), 500 of that XC (100 as PIC), 100 hours night (25 as PIC), and 75 hours real or simulated instrument time (no more than 25 hours in a flight simulator, 50 if you're training under Part 141), all in single-engine fixed-wings. If you then wanted to progress to multis and thus eventually become useful to a major U.S. domestic airline, you would have to start from scratch as a student pilot in the AMEL class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... Or would you? That's the question; how much of your flight time and/or certification level in one class is &quot;applicable&quot; by FAA regs toward any other class of the same category at the same level of certification? It seems unfair for a pilot with a fairly high ASEL certification to have to start from scratch on flight hours just to fly a plane with floats, or more than one engine, or both. However, they are different classes for a reason; more, or at least different, knowledge and experience is required to taxi a float plane on a lake or to get a multi-engine plane off the flight line. So while there is definitely a lot of overlap between the four &quot;Airplane&quot; classes, it's not 100%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about applicability of flight time and certifications to other categories? I'm particularly interested in the &quot;rotorcraft-gyroplane&quot; class and the &quot;powered lift&quot; category, as these were developed as aircraft hybrids which AFAIK have a significant skills overlap with a fixed-wing aircraft. Does flight time in an autogyro count in any capacity towards flight time in a fixed-wing, or vice-versa? How about flying a Harrier? In 50 years when the Osprey makes its way to GA in come capacity, how would existing civilian airplane and/or helicopter pilots get rated to fly it (I hope not by amassing 1,500 hours in an Osprey)? How about something &lt;em&gt;completely&lt;/em&gt; different? Even between a fixed-wing and a helicopter there's &lt;em&gt;some&lt;/em&gt; overlap (though I'd imagine even the chief pilot of a major airline would be out of his depth in a B204).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-30T01:42:28.110" LastActivityDate="2015-07-30T01:42:28.110" Title="How much knowledge/experience can be transferred between different categories/classes of certification?" Tags="&lt;flight-training&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16941" PostTypeId="2" ParentId="16940" CreationDate="2015-07-16T20:46:14.207" Score="8" Body="&lt;p&gt;The answers to your question lie in 14 CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1159&quot; rel=&quot;noreferrer&quot;&gt;61.159&lt;/a&gt; for airplanes.  Your quoted times for the ATP in the airplane category are correct but some of that time is total time as a pilot, some is just in category and only a small fraction of it is in category and class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in your hypothetical situation, you have an ATP in ASEL category/class and wanted to add the get the ATP AMEL.  All you need to do (aside from any knowledge tests you may require) is 50 hours in AMEL.  Of the 1500 hrs TT in airplanes, only 50 are required in class.  This is the same to add ASES and AMES ATPs.  You could have a certificate with ASEL,ASES,AMEL and AMES all that ATP level all with only 1500 TT as long as you had at least 50 hours in each class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The situation for rotorcraft/helicopter is similar and can be found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1161&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.161&lt;/a&gt;.  To get an ATP helicopter, you need 1200 hrs TT but the only hours that need to be in category and class are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;15 hours at night,&lt;/li&gt;&#xA;&lt;li&gt;200 hours w/75 PIC, and&lt;/li&gt;&#xA;&lt;li&gt;25 hrs in actual or simulated IMC&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You could accomplish all of that within the 200 required hours.  The 200 hours needed in helicopter still count as total time and can be applied toward a fixed wing ATP. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATP powered-lift requires 250 hours PIC in category with some sub-requirements out of that 250 hours&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;100 XC powered-lift&lt;/li&gt;&#xA;&lt;li&gt;25 night powered-lift&lt;/li&gt;&#xA;&lt;li&gt;75 instrument hours powered-lift&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The FAA does not currently issue ATP in rotocraft/gyroplane so you are out of luck there.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you wanted to min/max optimize the above requirements and get ATP in all of the above the hard category and class requirements boil down to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;50 hrs airplane single-engine land&lt;/li&gt;&#xA;&lt;li&gt;50 hrs airplane single-engine sea&lt;/li&gt;&#xA;&lt;li&gt;50 hrs airplane multi-engine land&lt;/li&gt;&#xA;&lt;li&gt;50 hrs airplane multi-engine sea&lt;/li&gt;&#xA;&lt;li&gt;200 hrs rotorcraft helicopter&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;15 hrs at night&lt;/li&gt;&#xA;&lt;li&gt;75 hrs pilot in command&lt;/li&gt;&#xA;&lt;li&gt;25 hrs actual or simulated IMC&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;250 hrs powered lift pilot in command&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;100 hrs cross country&lt;/li&gt;&#xA;&lt;li&gt;25 hrs night&lt;/li&gt;&#xA;&lt;li&gt;75 hrs actual or simulated IMC&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At this point you would have:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;650 hours TT&lt;/li&gt;&#xA;&lt;li&gt;325 hours PIC &lt;/li&gt;&#xA;&lt;li&gt;40 hours night&lt;/li&gt;&#xA;&lt;li&gt;100 hours cross country&lt;/li&gt;&#xA;&lt;li&gt;100 hours instrument&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now lets fly 400 hours XC in a single engine (slow and economical) with at least 60 of those hours at night and all of it PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we have&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1050 TT&lt;/li&gt;&#xA;&lt;li&gt;725 PIC &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;400 hrs airplane (at least)&lt;/li&gt;&#xA;&lt;li&gt;75 rotorcraft helicopter&lt;/li&gt;&#xA;&lt;li&gt;250 powered-lift&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;500 XC&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;400 hrs in airplane&lt;/li&gt;&#xA;&lt;li&gt;100 hrs in powered lift&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;100 night&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;60 hrs in airplane&lt;/li&gt;&#xA;&lt;li&gt;15 in helicopter&lt;/li&gt;&#xA;&lt;li&gt;25 in powered-lift&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Unless I'm missing something, this is all of the requirements for the ATPs except total time.  Go fly anything for another 150 hours and then take the ATP helicopter checkride.  Then fly another 300 hours in anything and take all of the other ATP checkrides with 1500 TT.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It is also worth pointing out that type ratings and ATPs are different things.  A type rating can be added to a private pilot certificate (though the checkride will be conducted at ATP standards).  You can also earn your ATP in an airplane that doesn't require a type rating (e.g. getting an ATP AMEL in a Piper Seminole).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-16T21:04:22.013" LastActivityDate="2015-07-16T21:04:22.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16942" PostTypeId="2" ParentId="3513" CreationDate="2015-07-16T21:47:00.503" Score="6" Body="&lt;p&gt;I'd say choice between a turboprop or a reciprocating engine may depend on your power needs, and the type of 'mission' the engine/aircraft will endure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbines and Turboprops, even with its advantage of weight to power ratio, are not that good regarding SFC, if you check this in www-jet-engine.net civil turboshaft-turboprop specifications, most of it have an SFC in the range of 600 lb/shp/hr, or more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Harry Ricardo and Roy Fedden Single Sleeve-Valve distribution Aircraft Engines provided the best ever SFC in a gasoline aircraft engine: 0.42 lb/BHP/hr in an Hercules Centaurus, 3272 cu. in., with a weight of 2695 lb, for a power of 3150 HP. Even more impressive results were obtained with an Open-Sleeve, acting as an annular piston with 10% of piston area, transmitting 3% of power, in an experimental 2-Stroke Compression Ignition Engine by Harry Ricardo. No Sleeve-Valve engine is produced today, but new replacement sleeves for old engines are still manufactured, they said this in AEHS, but I failed in locating the seller of Sleeves for old SSV engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best SFC ever seems being obtained in an open-sleeve valve, two-stroke, compression ignition engine, by Harry Ricardo, at 0.34 lb/HP/hr ('The high speed internal combustion engine', 1968 ed)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A poppet valve engine of the times of Bristol Hercules, the Wright R-3350, 2907 lb weight, also air-cooled, with same number of 18 cylinders; 3348 cu. in.; 2800 HP, used 0.72 lb/HP/hr, but this was greatly improved in the Turbo-Compound units, that added 500 lb weight more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Sleeve-Valve engines were known for its reliability and low wear, the no-lubrication zones of TDC and BDC are wiped out by the continuous sleeve movement, the Bristol Hercules had a TBO of 3000 hr or more, for 2000 hr TBO in the Wright cited (data in AEHS and other sources). Sleeve-valve engines, having no hot spots in combustion chamber, can work on low octane fuel at higher Compression Ratios than poppet valve engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The experimental Single-Cylinder, 500 cc, Sleeve-Valve gasoline unit built by Mike Hewland for Automobile use was reported having an SFC of 0.45 lb/HP/hr in the racing version, and 0.39 lb/HP/hr in the economical version (Car&amp;amp;Driver, July 1974), working even with creosote.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Rolls-Royce Turboprop, the Dart RDa 10.1 series, with 2915 HP and a weight of 1207 lb, consumed 0.550 lb/HP/hr.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can't find today reciprocating engines in power ranges above a certain limit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wankel Rotary Combustion Engine, that had extensive development for aviation and other uses by Curtiss-Wright, John Deere, NASA, NSU-Citroën, Sachs, Aixro, Rolls-Royce, Mazda, had an SFC of 0.46 lb/HP/hr with a weight of around 210 lb for a power output of some 120 HP, street car version, as reported in an early Mazda NA Wankel Engine, 2 Rotor, liquid cooled, a Wankel will work with no toil with unleaded gasolines around 80-90 ON, also with 10% Gasohol, that provides lower SFC and reduced operation temperatures and thermal load, some added lubricating oil to fuel and working chambers is always used in Wankels, no need of changing lubricating oil. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A major breakthrough was achieved recently in the Florida University, where they proved that adding: 'Heat Pipes', for cooling the housing and side plates of a formerly air-cooled housing charge cooled rotor UAV UEL engine reduced maximum temperature to a mere 129º C, and maximum temperature difference between engine parts to 18º C, the use of: 'Heat Pipes' for cooling Wankel RCEs, as it were used in satellites, may be an enormous step forward in Rotary Combustion Engines, as it eliminates most if not all thermal dilatation differences between parts of engine, making design and construction much easier, also improving reliability, from a reduced wear, enhancing power, reducing emissions and boosting fuel economy. Who could ask for anything more?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standards for reciprocating aviation engines were around 1 kg/HP weight to power ratio, and 250 gr/HP/hr SFC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No Wankel Rotary Combustion Engine seems having obtained yet an FAA certification for regular general aviation use, even when it are considered safer than reciprocating engines, Wankel RCEs failures tend not being total and instant as in reciprocating engines, a residual temporary lower power working would allow for more safe landing opportunities, this safety concern was approached by something close to the basic concepts in an hybrid car by Axteraerospace.com &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is an example of Turbine for General Aviation build in Argentina, basic arrangement reminds the first Turbine by Hans Joachim Pabst von Ohain &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/blt-jSWzsSI?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; &lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2016-07-19T19:20:15.017" LastActivityDate="2016-07-19T19:20:15.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16943" PostTypeId="2" ParentId="16891" CreationDate="2015-07-16T23:18:00.080" Score="3" Body="&lt;p&gt;Mark Clark, the owner of &lt;a href=&quot;http://www.courtesyaircraft.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Courtesy Aircraft&lt;/a&gt;, has the following pilot certificate, which allows him to fly anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/YyYCX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-07-16T23:27:17.417" LastActivityDate="2015-07-16T23:27:17.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16944" PostTypeId="1" AcceptedAnswerId="16945" CreationDate="2015-07-17T01:01:46.373" Score="2" ViewCount="423" Body="&lt;p&gt;How much damage could a total landing gear malfunction do to an airliner? Could the runway wear a hole through the plane?&lt;/p&gt;&#xA;" OwnerUserId="9403" LastEditorUserId="3825" LastEditDate="2015-07-17T04:21:17.277" LastActivityDate="2015-07-17T04:41:13.187" Title="How much damage could a landing gear malfunction do?" Tags="&lt;airliner&gt;&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16945" PostTypeId="2" ParentId="16944" CreationDate="2015-07-17T01:28:51.240" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Belly_landing&quot; rel=&quot;nofollow&quot;&gt;Belly landing&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During a belly landing, there is normally extensive damage to the airplane. Belly landings carry the risk that the aircraft may flip over, disintegrate, or catch fire if it lands too fast or too hard. Extreme precision is needed to ensure that the plane lands as straight and level as possible while maintaining enough airspeed to maintain control. Strong crosswinds, low visibility, damage to the airplane, or unresponsive instruments or controls greatly increase the danger of performing a belly landing. Still, belly landings are one of the most common types of aircraft accidents, and are normally not fatal if executed carefully.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is possible that the friction from a belly landing could wear a hole through the underside of the fuselage. However, even if this were to happen, airliners carry the passengers and crew in the upper half of the fuselage, so nobody would be likely to notice (from inside the aircraft before emergency evacuation).&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-07-17T01:28:51.240" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16946" PostTypeId="2" ParentId="2917" CreationDate="2015-07-17T01:49:38.520" Score="4" Body="&lt;p&gt;This question is quite broad, as airspace classes are used in varying ways by different jurisdictions. The only near-constant is what the airspace classes mean in terms of the services Air Traffic Control must provide and the conditions under which planes may use the space. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, you must understand four basic modes of aircraft operation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Visual Flight Rules (VFR)&lt;/strong&gt; - Pilots fly the plane primarily by looking outside the cockpit, using the horizon to know how their aircraft is oriented, landmarks to navigate, and visual contact with other planes and airborne objects to safely &quot;separate&quot; his aircraft and avoid collisions (a mentality known as &quot;see and avoid&quot; which is required of all pilots when it is possible). This is the simplest mode of operation and the first that pilots learn, but requires good weather, especially good visibility distance (3 miles or better) and a high cloud ceiling (1,000 feet or higher). The minimal conditions required for VFR are known as &quot;visual meteorological conditions&quot; or VMC.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Instrument Flight Rules&lt;/strong&gt; - Pilots fly the plane using primarily instruments inside the cockpit for orientation and navigation of the aircraft, while Air Traffic Control (ATC) issues directions to aircraft regarding course and to maintain separation between one plane and another and direct planes onto the correct course, especially for landings. This requires pilots to receive special training on the instruments they'll use and in radio procedures, and allows flight in any weather that doesn't meet the minimum criteria for VMC but still allows the flight of aircraft (fog, low clouds, light rain, dust storms), which is known as &quot;instrument meteorological conditions&quot; or IMC.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Special Visual Flight Rules (SVFR)&lt;/strong&gt; - An exceptional case in which pilots are allowed to fly under VFR within controlled airspace in weather conditions marginally worse than the minimums in which VFR is normally allowed. ATC is required to track the aircraft and provide separation even if the airspace class wouldn't normally require ATC to do this for VFR traffic. This is typically used to get planes into or out of an airport that is experiencing localized worsening weather, without those pilots having to declare an emergency to override the controller's lack of clearance (normally if the airport is experiencing IMC it is illegal for a controller to clear a VFR flight for landing or even entry, as it's illegal for the aircraft to operate under VFR in such conditions).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;VFR-On-Top&lt;/strong&gt; - This is a special case of IFR which requires the same instrument training and certification, but allows a more VFR-like flight experience for the pilot. The pilot will be granted a &quot;slice&quot; of airspace by ATC, either altitude-only along his flight path or in three dimensions, within which the pilot has the freedom to choose his own altitude (typically to avoid clouds). The pilot gains primary responsibility to maintain minimum distances from other aircraft and from clouds within this airspace as he would under VFR.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As defined by ICAO, the classes are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class A&lt;/strong&gt; - All flights must operate using IFR; no VFR or SVFR flight is allowed and VFR-On-Top is typically not granted due to the high activity level. Planes entering Class A airspace or making any self-directed change in flight path require ATC clearance. ATC provides full separation services, providing instructions to aircraft regarding required heading and altitude to keep aircraft on-course and well-spaced.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class B&lt;/strong&gt; - Flights can use all four flight rulesets, however all aircraft must be in contact with ATC and receive explicit clearance for entry or flight path deviation. ATC provides full separation services to all aircraft as well as directional guidance to IFR and SVFR.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class C&lt;/strong&gt; - Flights can use any of the four flight rulesets. Aircraft must be in contact with ATC and (except in certain countries including the U.S.) require explicit ATC clearance. ATC provides IFR guidance and separation of IFR and SVFR craft from each other and from VFR craft, while VFR craft receive &quot;traffic advisories&quot; but must maintain their own separation from each other.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class D&lt;/strong&gt; - Flights can use all four rulesets. Aircraft must be in contact with ATC and (except in certain countries including the U.S.) must receive explicit clearance for entry. ATC provides separation of IFR and SVFR flights from each other and provides traffic advisories to these craft of nearby VFR planes; VFR traffic may receive traffic advisories but is responsible for their own separation from all other aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class E&lt;/strong&gt; - Flights can use IFR, VOT or VFR; SVFR is allowed only when the airspace is established around a towered airport. IFR and SVFR flights are separated by ATC and require ATC communication and clearance prior to entry if the airspace is established around an airport; VFR aircraft do not require clearance or ATC communication, and do not receive separation services (though they may receive traffic advisories, ATC workload permitting).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class F&lt;/strong&gt; - Flights can use IFR, VOT or VFR but not SVFR. No clearance is required and ATC communication is only required for IFR. ATC provides separation between IFR flights and traffic advisories based on ability and workload, but separation is not guaranteed and IFR flights gain responsibility to &quot;see and avoid&quot;. VFR flights may receive traffic advisories from ATC on a workload-permitting basis.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Class G&lt;/strong&gt; - Flights may use IFR, VOT or VFR but not SVFR. No clearance is required and communication is only required for IFR. ATC has no authority or responsibility within this airspace; it provides traffic advisories as it is able prioritizing IFR flights.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the United States, the classes are used as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;A&lt;/strong&gt; - Airliner cruising altitudes, beginning at about 18,000 feet up to 60,000 feet within U.S. territorial boundaries and additional monitored airspace in international waters.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;B&lt;/strong&gt; - Surrounds large national and international hub airports in a big &quot;inverted wedding cake&quot; shape beginning at the surface 10 miles out and proceeding upward in wider layers to 10,000-12,000 feet at 20-30 miles out (the exact shape and number of layers depends on the specific needs of the airport and surrounding airfields or terrain); examples include Chicago O'Hare (ORD), Hartsfield-Jackson Atlanta (ATL), the Dallas-Fort Worth area (DFW/DAL), Boston Logan (BOS), the Washington, DC area (IAD/DCA/BWI), Los Angeles (LAX), San Francisco (SFO), Denver (DEN), the Houston area (IAH/HOU) and a few others.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;C&lt;/strong&gt; - Surrounds any airport that isn't Class B or within the footprint of one, but has significant scheduled service from national airlines (basically if it sees regular service from a 737 or larger it's at least Class C). Airspace shape is a smaller &quot;inverted birthday cake&quot; with an inner cylinder at the surface to 2,000 feet 5 miles in radius, and an upper cylinder from 2,000' to 4,000' feet at 10 miles out, with tweaks as necessary to accommodate the airport's specific needs.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;D&lt;/strong&gt; - Surrounds any airport that isn't class B or C but has a tower and instrument approach services. Includes most U.S. airports with commercial service using smaller narrow-body jets and turboprops, as well as most military air bases (AFB/NAS/JRB). Airspace shape is typically a single cylinder 4 miles in radius extending to 2500 feet; small variations are allowed.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;E&lt;/strong&gt; - Any airspace underneath Class A that isn't B, C, or D but can still be controlled by ATC. Typically starts at 1,200 feet above ground and extends upward to class A; a lower 700' &quot;floor&quot; is established 5 to 10 miles outside and underneath the airspace near most towered airports, with airstrips that do not have their own tower but do have instrument approach services also having a Class E &quot;surface footprint&quot; of 3 miles radius. This airspace is typically where ATC will grant &quot;VFR-On-Top&quot; clearance.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;F&lt;/strong&gt; - Not used in the U.S.; by FAA law, all &quot;controlled&quot; airspace requires ATC to guarantee IFR-IFR separation; any space in which it cannot do so is &quot;uncontrolled&quot; Class G.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;G&lt;/strong&gt; - Anything that isn't Class A-E. Typically airspace from the surface to 1,200 feet AGL, except where the Class E floor is lowered below 1,200'AGL, or any region above 1,200'AGL where radar or radio communications is disrupted by surrounding terrain.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T15:19:38.017" LastActivityDate="2015-07-23T15:19:38.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16947" PostTypeId="1" AcceptedAnswerId="17103" CreationDate="2015-07-17T03:21:28.283" Score="7" ViewCount="1965" Body="&lt;p&gt;In response to my &lt;a href=&quot;https://aviation.stackexchange.com/questions/16935/why-arent-modern-helicopters-quieter&quot;&gt;question&lt;/a&gt; about quieter helicopters,  KeithS mentioned the Eurocopter Blue Edge helicopter blade design. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to an &lt;a href=&quot;http://www.wired.com/2010/02/eurocopter-moves-one-step-closer-to-whisper-mode/&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; I found on them, there appears to be two components at the very least: a boomerang style rotor tip (Blue Edge) and piezoelectric active flaps (Blue Pulse) on the trailing edges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do these (as well as other changes) affect the noise level (i.e., what is the aeronautic principle behind their design)? Also, the sound reduction itself seems relatively modest (3-4 decibels), but is the quality or tone of the sound perceptually different such that it seems much quieter? &lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-21T21:01:21.313" Title="How does the Eurocopter Blue Edge and Blue Pulse rotor blade design work?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;noise&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16948" PostTypeId="1" AcceptedAnswerId="16958" CreationDate="2015-07-17T03:40:21.733" Score="20" ViewCount="20840" Body="&lt;p&gt;In my question about helicopter noise, I made the assumption that one reason they are so darn noisy is that the main rotor tips go faster than the speed of sound. @FreeMan questioned whether that was the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've tried to find information about this but most pages end up discussing V&lt;sub&gt;NE&lt;/sub&gt; -- the forward speed at which the advancing blades go supersonic while the retreating blades lose lift and stall. This is not about that situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is about regular flight -- is the extremely loud noise from helicopters because their rotor tips are supersonic, or is from other sources?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;p.s. There is some mention that the &quot;WOP-WOP&quot; of descending helicopters is caused by the rotor tips going supersonic. Is this the case - and if so, is it an edge case (the only time the tips are supersonic) or just one example of when they do. &lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastActivityDate="2020-02-23T15:45:35.967" Title="Do helicopter rotor tips regularly go supersonic?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;noise&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16949" PostTypeId="1" AcceptedAnswerId="16967" CreationDate="2015-07-17T03:47:37.297" Score="6" ViewCount="591" Body="&lt;p&gt;Inspired by &lt;a href=&quot;https://aviation.stackexchange.com/questions/16940/how-much-knowledge-experience-can-be-transferred-between-different-categories-cl&quot;&gt;KeithS's question about ATPLs and category/class ratings&lt;/a&gt;, I figured I'd throw another type-rating/airline-operations puzzler at you: are there any aircraft currently in scheduled airline service (i.e. operated under part 121) which would &lt;em&gt;not&lt;/em&gt; require a type rating to fly?  (I know part 135 operators often fly small aircraft due to the nature of their operation, with more intermittent or even on-demand service and the smaller locales they fly into.)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-07-17T15:32:40.660" Title="Are there any aircraft used in part 121 (aka scheduled airline) operations that do not require a type rating to fly?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;&lt;type-ratings&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16950" PostTypeId="2" ParentId="12162" CreationDate="2015-07-17T03:52:50.700" Score="0" Body="&lt;p&gt;It all comes down to Newton's second law of motion in that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$F= m \cdot a$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trust required for a 70 m/sec. 10.000 kilos takeoff speed and weight with an acceleration of 2g is: 20 Kilo Newtons, it will take 35 seconds and 1225 meters of runway to become airborne .At the moment airplane manufacturers have to trade off Power and Speed to the best fuel economy. but with propellers a max speed is about 662 K hr ( SAAV 2000 ) and jets with a optimun speed is 880 k hrs. Both do not travel at the optimun speed for ANY airplane of around 700 kms per hour wich is where induced drag and atatic drag are at their lowest so a propeller airplane is slow and a jet is fast and the penalty is fuel consuption because the jet have travel at the speed of combustion in the engines and propellers can not be made bigger than they are now (speed of sound limits their size at the tips) &lt;/p&gt;&#xA;" OwnerUserId="9404" LastEditorUserId="572" LastEditDate="2015-07-17T07:28:06.670" LastActivityDate="2015-07-17T07:28:06.670" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16951" PostTypeId="2" ParentId="16944" CreationDate="2015-07-17T04:41:13.187" Score="1" Body="&lt;p&gt;This is highly unlikely -- there is a sturdy keel beam at the bottom of an aircraft's fuselage, similar to a ship's keel.  This beam serves as the main fore-and-aft member in the aircraft structure (its primary function is to transfer bending loads to the center wing box), and will take the brunt of the damage from a belly landing once the belly skin wears through.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, total belly landings are quite rare compared to partial gear landings, which are much kinder on the airframe itself (usually scraping a wingtip and/or an engine pod bottom cowl).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-07-17T04:41:13.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16953" PostTypeId="1" AcceptedAnswerId="16956" CreationDate="2015-07-17T06:41:07.393" Score="25" ViewCount="6245" Body="&lt;p&gt;Is it true that insects hitting the fuselage could decrease aircraft performance and increase fuel consumption? Insects are small in mass. I think even a large amount of them accumulate on the aircraft's outer skin, it wouldn't be significantly enough to affect fuel consumption.&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="946" LastEditDate="2015-07-17T12:31:48.893" LastActivityDate="2017-04-28T12:17:08.667" Title="How do insects decrease aircraft performance?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16954" PostTypeId="2" ParentId="16953" CreationDate="2015-07-17T07:14:46.820" Score="12" Body="&lt;p&gt;The issue here is not the additional mass or weight, but the disturbed airflow over the wings. The key terms here are laminar flow and turbulent flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The below picture will show normal laminar and turbulent flow over a wing. With insects or other dirt on the leading edge, the transition will happen closer to the front, leading to a decrease in performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/hYRmk.gif&quot; alt=&quot;Laminar Flow&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.allstar.fiu.edu)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.nasa.gov/topics/aeronautics/features/bug_team.html&quot; rel=&quot;noreferrer&quot;&gt;NASA has done some reasearch&lt;/a&gt; too:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Anyone who has driven through a cloud of insects knows how quickly the bug guts build up on the vehicle, causing problems with visibility, clogging the air intake and radiator, and ruining the car's exterior finish.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The problem for an airplane is that its aerodynamic design is meant to have air move very smoothly across the body and wing surfaces, which is called laminar flow. When there is a disruption in that laminar flow, such as from the accumulation of dead bug parts, you induce the opposite of laminar flow, which is turbulence.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Finding ways to maintain laminar flow through all phases of flight is a big deal for the aviation community because it could save millions in fuel cost, while also reducing the amount of noxious emissions released into the atmosphere.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-07-17T07:31:32.910" LastActivityDate="2015-07-17T07:31:32.910" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="16956" PostTypeId="2" ParentId="16953" CreationDate="2015-07-17T08:14:28.467" Score="28" Body="&lt;p&gt;You're right, insects are very small, so they influence things which happen on their scale. The one important phenomenon on an airliner which has the scale of insects is the &lt;a href=&quot;http://aerojockey.com/papers/bl/node1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;boundary layer&lt;/a&gt;, the sheet of air around all wetted surfaces where air speed changes from zero (relative to the plane) to the speed it has at some distance. This is called the boundary layer. Its thickness changes from zero at the stagnation point to several centimeters at the end of a long fuselage.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What does the boundary layer look like?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At the leading edge, the boundary layer starts with a thickness of zero. Now friction with the wing will cause some air molecules to be slowed down, and soon you get a sheet of air in which the molecules closest to the aircraft's skin will move with the skin, and the more you move away from the skin, the less they are slowed down. Initially, the layers of air within the boundary layer show no cross movement of molecules. Compare it with a multi-lane road with bumper-to-bumper traffic where no car changes lanes. Since all molecules move along their layer of air, this is called laminar flow (lat. lamina = layer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point downstream &lt;a href=&quot;https://en.wikipedia.org/wiki/Tollmien%E2%80%93Schlichting_wave&quot; rel=&quot;nofollow noreferrer&quot;&gt;oscillations will develop&lt;/a&gt;, and once they become unstable, molecules will move between the layers of air. Now you have faster ones from more distant layers moving closer to the skin and kicking the slow ones there ahead, and slower ones from close to the skin moving away, slowing down the more distant layers. Now the cars in your multi-lane road cross lanes, and the result is that all lanes but the rightmost one will move at similar speed. Since the cross-flow is the result of turbulence, this boundary layer is called turbulent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AsLrr.gif&quot; alt=&quot;Speed profiles of laminar and turbulent boundary layers&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed profiles of laminar (left) and turbulent (right) boundary layers. Image &lt;a href=&quot;http://aerojockey.com/papers/bl/node1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Consequences for drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The cross flow causes the turbulent boundary layer to have a much steeper speed gradient at the aircraft skin, causing much more friction drag. At the same time, more energy is taken from the flow due to friction, so the whole boundary layer becomes thicker. If you look at the local friction drag, the parameter plots made possible by &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;nofollow noreferrer&quot;&gt;XFOIL&lt;/a&gt; are quite illuminating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lNA8N.png&quot; alt=&quot;E502mod at 3° AoA, friction plot&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Friction drag over chord for an E502mod airfoil at 3° AoA. Blue: Top surface, Red: Bottom surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot shows the friction over chord for an airfoil at 3° angle of attack. All flow is attached (save for one small separation bubble on the bottom near the transition point). Can you spot the transition points from laminar to turbulent flow? Yes, it's where the friction drag jumps up and stays annoyingly high downstream. Note that the flow around an airliner's wing happens at a much higher &lt;a href=&quot;https://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds Number&lt;/a&gt;, so the transition points are closer to the leading edge than in the plot above. I chose the low Reynolds Number in the plot above because it shows the phenomenon more clearly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you see also a friction spike at the nose! This is caused by the very small thickness of the young boundary layer. Even though it is laminar, it shows a high friction contribution simply because it is still very thin. Now imagine you have both effects, a thin boundary layer and the bigger friction of a turbulent boundary layer, added together. This is what bugs at the leading edge of the wing will give you! They make the wing's surface rough and drive up friction losses due to an early transition of the boundary layer into turbulent flow.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Consequences for maximum lift&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;But there is also a second effect: The longer the boundary layer develops, the more the flow loses the ability to slow down and increase pressure towards the trailing edge. A flow's energy is either speed or pressure, but if the energy of the flow is sapped by friction, none of both is left when needed to negotiate the last half of the wing's shape. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;The flow will separate earlier&lt;/a&gt; if it had been turbulent from the beginning, and the wing will stall at a lower angle of attack. This is the second negative consequence of bugs on a wing. It can be mitigated by careful airfoil design, but then this airfoil will show lower bug-free performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glider pilots know this very well, especially those who flew &lt;a href=&quot;https://en.wikipedia.org/wiki/Eiri-Avion_PIK-20&quot; rel=&quot;nofollow noreferrer&quot;&gt;planes&lt;/a&gt; which used the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=fx67k170-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wortmann FX 67-170 airfoil&lt;/a&gt;. It had excellent L/D without bugs, but both rain and bugs converted the plane to something resembling a brick. I once flew a &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Janus&quot; rel=&quot;nofollow noreferrer&quot;&gt;Janus B&lt;/a&gt; into a shower, and minimum speed increased from 80 km/h to 110 km/h. A few seconds of flying at higher speed cleaned the wing, but then it was time to land, because I had lost so much altitude. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-03-30T21:19:35.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16957" PostTypeId="1" CreationDate="2015-07-17T08:35:24.460" Score="28" ViewCount="13306" Body="&lt;p&gt;By &quot;good reason&quot;, I mean a reason that we definitely cannot overcome with reasonable changes in aircraft design, control laws or procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As possible benefits of this I see a much smaller (= lighter) tail landing-gear than the nose landing-gear. Also, an opportunity to reduce tail-strike margins (=increase incidence, reduce landing speed). And of course there is all that space at the front of the fuselage that is freed for other uses (systems, cargo, stairs,...?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One drawback is of course passenger comfort. But passengers already experience high pitch angles during climb, and we could imagine to have the tail of the aircraft raised up (on a stand?) for boarding/deboarding. Also the APU has be moved (but I don't think this is impossible).&lt;/p&gt;&#xA;" OwnerUserId="9059" LastEditorUserId="19" LastEditDate="2017-09-19T15:44:52.717" LastActivityDate="2020-11-09T07:56:04.070" Title="Is there a good reason why modern airliners can't have conventional landing gears (vs. tricycle landing gears)?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;&lt;tail-dragger&gt;" AnswerCount="8" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16958" PostTypeId="2" ParentId="16948" CreationDate="2015-07-17T08:57:08.540" Score="23" Body="&lt;p&gt;The &quot;wop wop&quot;, usually known as blade slap, is heard when the tip of the blade passes through the vortex created by the previous one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be avoided.  The most common flight regime when this happens is a shallow descent but still with quite a lot of power - e.g. fast and shallow.  The vortex starts to move down as soon as it leaves the tip of the blade so in level flight, the following blade passes over it.  In a shallow descent with high pitch angle, the following blade can literally &quot;slap&quot; into the previous vortex.  The vortices of the two blades now interact and can cause local, transient supersonic flow.  To avoid it, simply lower the pitch to establish a more positive descent or pull back on the cyclic to increase disc loading and flatten the attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blade tips do not go supersonic.  In fact, in nearly all helicopter designs, the rotor rotates within a very narrow range of speeds, typically between 90% and 110% of the normal speed.  In most flight regimes, the rotor is rotating at 100%, +/- a few percent, whether you are climbing, descending or cruising.  Only during auto-rotation and aggressive manoeuvring does the range vary by 10% or more.  It depends on the type of helicopter but absolute limits would be something like 85% (panic time, risk of complete stall) and 115% (smaller panic, risk of damage to the machine, especially in the tail rotor drive shaft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In normal operations, and design aims to achieve this, the rotor tips do not go supersonic&lt;/strong&gt; since when they do, there is a sudden and large decrease in performance with more power required, higher blade loads, vibration and noise.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think about a helicopter flying forwards.  The advancing blade at its most perpendicular position experiences a relative airflow which is equal (ignoring all kinds of minor side effects) to the forward speed plus the speed of the blade.  The retreating blade is experiencing a relative airflow equal to the speed of the blade minus the speed of the helicopter.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the blades rotate so fast that the tips are supersonic, then the main lift generating part of the retreating blade, the outer two thirds of the span, would experience such a low airspeed, for some of the span it will even be negative, that the blades will stall causing a catastrophic roll into that side.  It is this phenomenon which ultimately limits the rotational speed of the blades and the maximum speed of the helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the R22 as an example.  The following figures are approximate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotor tip speed is about 670 fps (feet per second).  The speed of sound at ground level on a standard day is about 1100 fps.  The R22 is flying at close to VNE, let's say 100kts which is about 170 fps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tip on the advancing side, at it's fastest, is therefore flying relative to the airflow at 840 fps and on the retreating side, at it's slowest, at 500 fps.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blade length is about 11 feet, so the middle portion of the blade on the retreating side is only flying at 190 fps (half of 670 minus the airspeed).  When you get to about 4 feet out from the blade root, it's now only 50 fps and not much further in from that, becomes zero, then negative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that lift is proportional to the square of the speed.  You can now see the huge discrepancy between lift on either side as airspeed increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question directly, the R22 would need to fly at 530 fps to approach supersonic tip speed which equates to about 330 kts which it can't get anywhere near achieving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS.  The R22 POH speaks in Imperial measures.  When I get some time, I'll redo the figures in metric which I, and most of the world, prefer.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-11-17T07:57:35.307" LastActivityDate="2016-11-17T07:57:35.307" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16959" PostTypeId="2" ParentId="16957" CreationDate="2015-07-17T08:57:12.877" Score="24" Body="&lt;p&gt;I don't think there is a reason they &lt;em&gt;can't&lt;/em&gt; have conventional landing gear (tail wheel). But there are simply &lt;em&gt;many&lt;/em&gt; advantages to tricycle landing gear:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft with tricycle landing gear is directionally stable and therefore easier to control especially with cross-wind.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft with tricycle landing gear has level attitude on the ground, which provides:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Good visibility during taxiing and take-off and landing runs. Many tail-draggers have &lt;em&gt;no&lt;/em&gt; forward visibility during taxiing!&lt;/li&gt;&#xA;&lt;li&gt;Easier loading and unloading.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Since the main gear is aft of centre of gravity, aircraft with tricycle landing gear are less prone to bouncing on touch-down.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Conventional gear has less drag when it is non-retractable, but airliners all have retractable landing gear. The only other advantage is lower weight (the tail-wheel is lighter than nose-wheel), but that difference is not worth all the disadvantages for airliners.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-17T08:57:12.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16960" PostTypeId="2" ParentId="16957" CreationDate="2015-07-17T10:43:06.543" Score="3" Body="&lt;p&gt;One of the reasons tricycle gears are popular are the fact that they help give plenty of propeller clearance. However, turbofans are by design normally smaller in diameter (They will accelerate a smaller volume of air to a higher velocity in comparison). Hence this is less of a concern. This would also imply that jet engines aligned with the aircraft body would be blasting the runway quite powerfully at full thrust, which would accelerate wear.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-17T13:23:17.367" LastActivityDate="2015-07-17T13:23:17.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16961" PostTypeId="2" ParentId="16957" CreationDate="2015-07-17T11:42:44.667" Score="14" Body="&lt;p&gt;Other answers have given all the good reasons you need, but there is one more that should not be discounted:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a plane with conventional landing gear, when on the ground, the fuselage is standing at a angle to the ground that is not insignificant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that passengers will have to walk uphill when boarding from the rear door or downhill when boarding from the front door. Same issue when disembarking, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can try this if you get the chance to visit a DC-3, of which quite a few are still flying with passengers (although the large majority are effectively run as museum pieces, many are still airworthy). A (hypothetical) modern airliner would probably be longer than the DC-3, and the effect hence presumably less pronounced, but still very real.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect of the difficulties of such a sloping aisle would be longer turn-around times (and short turn-arounds are the holy grail of low-cost operators), which would have to be offset by equal savings generated by the conventional landing gear.&lt;/p&gt;&#xA;" OwnerUserId="2176" LastActivityDate="2015-07-17T11:42:44.667" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16962" PostTypeId="2" ParentId="16957" CreationDate="2015-07-17T12:07:47.773" Score="55" Body="&lt;p&gt;Short answer: Yes. Not one, but several. A taildragger configuration for modern airliners comes with several disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Visibility during taxiing is much worse.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/h0Iro.jpg&quot; alt=&quot;Ground collision with taildragger&quot;&gt;&#xA;Visibility while taxiing &lt;strong&gt;is&lt;/strong&gt; a safety-relevant issue (Picture &lt;a href=&quot;http://www.pprune.org/aviation-history-nostalgia/288043-ground-collision-pictures.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Braking hard will result in a headstand. And with today's landing speeds, braking hard is needed if you want to fly from standard length runways. Carrier-borne aircraft were the first to feel this consequence of increasing landing speeds, so they converted first to tricycle gears.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/XxabX.jpg&quot; alt=&quot;TBM-3U after having landed on wheels and nose&quot;&gt;&#xA;That is what is colloquially called a &quot;headstand&quot; (Picture &lt;a href=&quot;http://replicainscale.blogspot.de/2011/08/walkin-dog-chief-goes-to-france-hawks.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Loading and unloading will become more complicated. The current way of sliding containers manually on a flat deck would need to be replaced by internal winches pulling the containers up the ramp to the door.&lt;/li&gt;&#xA;&lt;li&gt;Drag during ground roll is much higher as long as tail lift is not sufficient to get the tail up. Take-off distances would also become longer.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, it comes down to minimizing field lengths and increasing safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jms4K.jpg&quot; alt=&quot;MD-11 after loading mistake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who says there are no taildragger airliners? (Picture &lt;a href=&quot;http://www.iasa-intl.com/folders/belfast/Gemini_tipup/GeminiMD11-Dubai.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-06-23T11:42:33.573" LastActivityDate="2019-06-23T11:42:33.573" CommentCount="21" ContentLicense="CC BY-SA 4.0" />
  <row Id="16963" PostTypeId="2" ParentId="8642" CreationDate="2015-07-17T12:34:04.243" Score="13" Body="&lt;p&gt;Another option to build a helicopter without a tail, is to use active flapping.&#xA;Basically the idea is to not counteract the torque of the main rotor, but use a rotor concept that does not generate a torque.&lt;/p&gt;&#xA;&lt;p&gt;At the Technical University Delft they applied this principle to build the Ornicopter (a mix of the words helicopter and ornithopter), a tailless helicopter. Flight tests have been performed using this prototype.&lt;/p&gt;&#xA;&lt;p&gt;According to the university:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The Active Flapping&lt;/p&gt;&#xA;&lt;p&gt;The active flapping of blades is the key for the&#xA;Ornicopter concept. In this manner, the blade can generate a&#xA;propulsive force to rotate itself, and hence the shaft torque is not&#xA;needed. This results in a torque-less main rotor, i.e. the tail rotor&#xA;can be eliminated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://repository.tudelft.nl/islandora/object/uuid:63b3a329-66da-475f-a59a-5b6bf4b7dca8/datastream/OBJ/downloadLeerstoelen/Afdeling_C_O/Graduate_School_AE_01/PhD_Poster_Day_2014/Wan__Jia.pdf&quot; rel=&quot;noreferrer&quot;&gt;More info here&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/0Z2Rr39hiUs?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BCDzr.jpg&quot; alt=&quot;Ornicopter on TU Delft Aerospace Faculty grounds&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Concerning the question on scalability posed in one of the comments:&lt;/p&gt;&#xA;&lt;p&gt;I found a &lt;a href=&quot;https://repository.tudelft.nl/islandora/object/uuid:da36bee8-c128-49ea-812b-8976fa055426/datastream/OBJ/download&quot; rel=&quot;noreferrer&quot;&gt;PhD thesis on the topic&lt;/a&gt; (download)  which did a feasibility study on a Bo-105 scale ornicopter. The thesis says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&amp;quot;The thesis proves that the optimal design for the Ornicopter as&#xA;compared to the Bo-105 benchmark is characterized by a lower blade&#xA;loading, increased rotor tip velocity and larger vertical fin size.&#xA;This optimal design results in an enlarged flight envelope due to the&#xA;reduced rotor stall area and improved yaw stability in forward flight.&lt;/p&gt;&#xA;&lt;p&gt;Nevertheless, despite these improvements in the Ornicopter's flight&#xA;envelope, there is a slight increase in required power when compared&#xA;with the Bo-105 specification (approximately 5% at 150 knots).&lt;/p&gt;&#xA;&lt;p&gt;To compensate for the higher profile power needed for the Ornicopter's&#xA;optimal design, a larger rotor radius is required in order to reduce&#xA;the induced power and keep the increase in the total required power to&#xA;a minimum. This thesis may be considered as a first step in rationalizing the&#xA;expectations regarding the Ornicopter's tailless helicopter design.&lt;/p&gt;&#xA;&lt;p&gt;The thesis proved that this new concept shows a slightly poorer&#xA;performance than that of conventional helicopters regarding power&#xA;consumption in forward flight and service ceiling. This is&#xA;disappointing since one of the assumptions was that the elimination of&#xA;the tail rotor would also eliminate the power consumption associated&#xA;with a tail rotor. &amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-07-13T17:08:22.227" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16964" PostTypeId="2" ParentId="16949" CreationDate="2015-07-17T14:35:50.190" Score="1" Body="&lt;p&gt;I suspect you're thinking about passengers, not freight, but &lt;a href=&quot;https://www.faa.gov/about/office_org/field_offices/cmo/fedex/&quot; rel=&quot;nofollow&quot;&gt;Fedex is a part 121 operator&lt;/a&gt; that &lt;a href=&quot;https://en.wikipedia.org/wiki/FedEx_Express#Fleet&quot; rel=&quot;nofollow&quot;&gt;operates the Cessna 208 (Caravan)&lt;/a&gt;, which &lt;a href=&quot;http://registry.faa.gov/TypeRatings/&quot; rel=&quot;nofollow&quot;&gt;does not require a type rating&lt;/a&gt; in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regional airlines in Hawaii and Alaska also operate the 208, but they seem to be part 135 operations.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-17T14:35:50.190" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="16965" PostTypeId="2" ParentId="2126" CreationDate="2015-07-17T15:02:19.630" Score="5" Body="&lt;p&gt;The other answers here do a good job of explaining why the pilot should be able to decide when and if to put out an engine fire. This affects other design considerations as well. The potential for fire on an airplane is taken very seriously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot may decide to not put out a fire right away, but the fire suppression systems could also fail. To address this risk, airplanes are designed to minimize as much as possible the danger posed by a fire. This is described in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-135.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 20-135&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;5&quot;&gt;&#xA;  &lt;li&gt;a. The primary objectives of fireproof and fire resistant materials and components are to contain and isolate a fire and prevent other sources of fuel or air from feeding the existing fire, and to ensure that components of the engine control system will function effectively to permit a safe shutdown of the engine or APU and safe feathering of the propeller.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Components in fire zones near the engine or APU are required to be fireproof or fire resistant, which means maintaining functionality in the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fireproof: 2000°F flame (+/-150°F) for 15 minutes minimum&lt;/li&gt;&#xA;&lt;li&gt;Fire resistant: 2000°F flame (+/-150°F) for 5 minutes minimum&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Engine controls are generally required to be fire resistant, allowing the engine to be controlled or shut down and a fire extinguished even up to 5 minutes after a fire starts. Firewalls are generally required to be fireproof, containing the fire long enough to provide the pilot a chance to land the plane, or hopefully for the fire to burn out on its own, before spreading to other areas in the plane. This also allows for the fact that the fire detection system could take some amount of time to detect a fire, depending on the location and severity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AC goes into more detail about specific requirements and testing procedures. Of course the FAA has a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=sg14.1.25_1843.sg27&amp;amp;rgn=div7&quot; rel=&quot;noreferrer&quot;&gt;section of regulations&lt;/a&gt; on fire protection for airliners. The goal is to give the crew as much opportunity as possible to ensure the safety of everyone on board as is reasonably possible.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-07-17T15:02:19.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16966" PostTypeId="2" ParentId="16949" CreationDate="2015-07-17T15:15:20.680" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cape_Air&quot; rel=&quot;nofollow&quot;&gt;Cape Air&lt;/a&gt; seems to be a Part 121 carrier, and since they fly the Cessna 402, that might be an answer.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-07-17T15:32:40.660" LastActivityDate="2015-07-17T15:32:40.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16967" PostTypeId="2" ParentId="16949" CreationDate="2015-07-17T15:20:28.600" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cape_Air#History&quot; rel=&quot;nofollow&quot;&gt;Cape air&lt;/a&gt; has a fleet of 83 Cessna 402s, some of which are involved in its Part 121 operation.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-17T15:20:28.600" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16969" PostTypeId="1" AcceptedAnswerId="16974" CreationDate="2015-07-17T15:43:06.543" Score="13" ViewCount="6938" Body="&lt;p&gt;I'm working on a novel that, as part of the backstory, requires samples of a biological agent to be flown from Incirlik Air Base to labs across Europe, and then finally from the UK to the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the context of the story, time is critical. Using any currently available aircraft (large or small, civil or military, US or allied etc.), what is the shortest flight time that could realistically be achieved?&lt;/p&gt;&#xA;" OwnerUserId="9319" LastEditorUserId="3386" LastEditDate="2015-07-17T15:45:34.660" LastActivityDate="2019-05-05T20:05:35.663" Title="What is the fastest possible transatlantic flight today?" Tags="&lt;airspeed&gt;&lt;transatlantic&gt;" AnswerCount="7" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16970" PostTypeId="2" ParentId="16969" CreationDate="2015-07-17T15:50:39.030" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Blackstar_(spacecraft)&quot; rel=&quot;nofollow&quot;&gt;Project Blackstar&lt;/a&gt;'s speed (and very existence) is classified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can probably assume it can go Mach 6+ for sci-fi purposes.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-07-17T15:50:39.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16971" PostTypeId="1" AcceptedAnswerId="17079" CreationDate="2015-07-17T15:54:13.080" Score="4" ViewCount="15625" Body="&lt;p&gt;While looking into &lt;a href=&quot;https://aviation.stackexchange.com/q/16949/62&quot;&gt;this question&lt;/a&gt;, I found a &lt;a href=&quot;http://www.transportation.gov/policy/aviation-policy/certificated-air-carriers-list&quot; rel=&quot;nofollow noreferrer&quot;&gt;list&lt;/a&gt; of certificated air carriers on the US Department of Transportation website (there's &lt;a href=&quot;http://www.transportation.gov/policy/aviation-policy/commuter-air-carriers-list&quot; rel=&quot;nofollow noreferrer&quot;&gt;a list&lt;/a&gt; of commuter air carriers too). But, the list doesn't say if each one operates under part 121 or part 135, which the DoT &lt;a href=&quot;http://www.transportation.gov/policy/aviation-policy/licensing/US-carriers&quot; rel=&quot;nofollow noreferrer&quot;&gt;seems to consider&lt;/a&gt; an FAA question anyway:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As noted above, the economic authority issued to air carriers by the&#xA;  Department is separate from the safety authority (commonly referred to&#xA;  as Part 135 or Part 121 Operations Specifications) granted to them by&#xA;  the Federal Aviation Administration (FAA).  For safety authority&#xA;  application procedures and related questions, air carriers should&#xA;  contact the appropriate FAA flight standard district office based upon&#xA;  the geographical location of the air carrier&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA site has a &lt;a href=&quot;https://www.faa.gov/about/initiatives/atos/air_carrier/&quot; rel=&quot;nofollow noreferrer&quot;&gt;lot of information&lt;/a&gt; about part 121 operations, but at least as far as I could see there's no list of 121 or 135 carriers anywhere on their site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a list somewhere of current part 121 and/or 135 operators?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-12-30T02:03:07.377" Title="Is there a list of part 121 and/or 135 operators?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16972" PostTypeId="2" ParentId="16971" CreationDate="2015-07-17T15:59:48.060" Score="2" Body="&lt;p&gt;I have not found a list, but you can search for an airline &lt;a href=&quot;http://av-info.faa.gov/OpCert.asp&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a link on the page to &lt;a href=&quot;http://av-info.faa.gov/Definitions.asp&quot; rel=&quot;nofollow&quot;&gt;definitions of the terms&lt;/a&gt;. Basically, &quot;domestic&quot; and &quot;flag&quot; are FAR 121 operations, and &quot;commuter&quot; is FAR 135 operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationdb.com/Aviation/AirOperatorQuery.shtm&quot; rel=&quot;nofollow&quot;&gt;There is also an unofficial database here&lt;/a&gt; that will tell you which FAR an airline operates under.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-07-17T15:59:48.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16973" PostTypeId="2" ParentId="16969" CreationDate="2015-07-17T16:05:37.363" Score="5" Body="&lt;p&gt;The shortest on record (and more or less possible) was done in an &lt;a href=&quot;http://www.wvi.com/~sr71webmaster/srspee~1.htm&quot; rel=&quot;nofollow&quot;&gt;SR-71 Blackbird&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Exactly 1 hour 54 minutes and 56.4 seconds later, they had set a new world speed record from New York to London England. The average speed was 1,807 statute mph over the 3,461 statute mile course&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;nofollow&quot;&gt;Concorde&lt;/a&gt; set a commercial record and is the fastest practical plane you could get ahold of&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;on 7 February 1996 by British Airways' G-BOAD in 2 hours, 52 minutes, 59 seconds from takeoff to touchdown aided by a 175 mph (282 km/h) tailwind&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aerionsupersonic.com/&quot; rel=&quot;nofollow&quot;&gt;Areon&lt;/a&gt; company is working on a super sonic biz jet but it has not yet been released. For what its worth the SR-71 and Concorde are both no longer flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we are talking about a science fiction setting there are faster &quot;aircraft&quot; out there like the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot; rel=&quot;nofollow&quot;&gt;X-15&lt;/a&gt; rocket plane (the fastest maned in atmosphere vehicle ever built, however not air breathing) as well as many of the other planes from the &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_X-planes&quot; rel=&quot;nofollow&quot;&gt;X-Plane&lt;/a&gt; program. You could use any of the specs (or similar specs) to make up a plane of your choosing. For reference the fastest contraption we have dreamed up to date is the &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_X-43&quot; rel=&quot;nofollow&quot;&gt;X-43&lt;/a&gt; which clocks in at about 7000 MPH however it is un-maned. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an added bonus effect (for realism) you can throw in something about needing to cool the biological agent in transit, in the plane since high speed planes (like the Blackbird) get very very hot at speed due to air friction.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-17T17:29:40.940" LastActivityDate="2015-07-17T17:29:40.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16974" PostTypeId="2" ParentId="16969" CreationDate="2015-07-17T16:22:05.317" Score="17" Body="&lt;p&gt;The fastest air-breathing aerodynamic-lift craft for which a maximum speed is known to civilians, and that can support mid-air refueling for an unlimited range, is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow noreferrer&quot;&gt;SR-71 Blackbird&lt;/a&gt; at Mach 3.3. However, all known airframes of this model have been retired and mothballed as museum pieces, and the SR-71 runs on a special blend of jet fuel called JP-7 that is no longer in use by any production aircraft (the sole remaining use is for the X-51 scramjet testbed). So not only would you have to get the planes airworthy again (which would include repairing or replacing the wing spars, which were cut specifically to &lt;em&gt;ensure&lt;/em&gt; the planes would never fly again), you'd need a batch of &lt;a href=&quot;https://en.wikipedia.org/wiki/JP-7&quot; rel=&quot;nofollow noreferrer&quot;&gt;JP-7&lt;/a&gt; at both ends and likely a tanker in the air full of it to use a Blackbird for this hop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fastest aircraft readily available and best suited for the job would likely be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22 Raptor&lt;/a&gt;. It can cruise at Mach 1.82 in clean configuration without afterburners (the samples could be contained in a &quot;personal effects pod&quot; carried in the internal bays), and has a one-way range of about 2,000 miles between refuelings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt; can supercruise at Mach 1.5 and would be a good second choice or even a first choice, seeing as most of western Europe has these in service. You wouldn't have to get an F-22 over to Europe from an airbase in the States or the Middle East; there's a couple of RAF garrisons that operate the Typhoon about 30 minutes from Heathrow in Lincolnshire, and you only lose a few hundred miles an hour on the one-way trip.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2018-11-13T14:44:56.343" LastActivityDate="2018-11-13T14:44:56.343" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="16976" PostTypeId="1" AcceptedAnswerId="16978" CreationDate="2015-07-17T16:28:42.757" Score="8" ViewCount="6672" Body="&lt;p&gt;In &lt;a href=&quot;http://www.ultralighthomepage.com/FAR.part103.html&quot;&gt;FAR part 103&lt;/a&gt; when they are talking about visibility requirements for flying an ultralight, sometimes instead of giving exact distances, they will just say &quot;clear of clouds&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                                   Minimum&#xA;                                  flight&#xA;                                visibility&#xA;      Flight altitudes             /1/       Minimum distance from clouds&#xA;1,200 feet or less above the&#xA;surface regardless of MSL&#xA;altitude:&#xA;(1) Within controlled airspace      3       500 feet below, 1,000 feet above, 2,000 feet horizontal.&#xA;(2) Outside controlled airspace     1       Clear of clouds.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Or here:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                                      Flight&#xA;          Airspace                visibility        Distance from clouds&#xA;&#xA;Class G:&#xA;1,200 feet or less above the &#xA;surface (regardless of MSL&#xA;altitude)                       1 statute mile   Clear of clouds.&#xA;More than 1,200 feet above the&#xA;surface but less than 10,000&#xA;feet MSL                        1 statute mile   500 feet below.&#xA;                                                 1,000 feet above.&#xA;                                                 2,000 feet horizontal.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;What does &quot;Clear of Clouds&quot; mean in this context?  Just that I should remain clear of the clouds, or does it mean that the sky must be clear of clouds in the defined space?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if it does just mean I need to stay &quot;clear of the clouds&quot;, how exactly is that defined?  1000ft?  100ft? 10ft?  What exactly?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-17T16:35:28.350" LastActivityDate="2015-07-17T20:06:23.880" Title="What does &quot;clear of clouds&quot; mean in FAA FAR part 103?" Tags="&lt;faa-regulations&gt;&lt;ultralight&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16977" PostTypeId="2" ParentId="16976" CreationDate="2015-07-17T16:37:07.113" Score="5" Body="&lt;p&gt;&lt;code&gt;Clear of clouds&lt;/code&gt; means you should not fly through clouds. You may get as near as comfortable to clouds, but flying into a cloud is still prohibited. There is no definition with a particular distance that I am aware of.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-07-17T16:42:59.300" LastActivityDate="2015-07-17T16:42:59.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16978" PostTypeId="2" ParentId="16976" CreationDate="2015-07-17T16:38:17.003" Score="9" Body="&lt;p&gt;It means you have to stay outside the cloud while flying. You're expected to use your own good judgment (remember it is illegal to fly into the cloud, and if you don't have proper instruments and know what you're doing, it's downright deadly) but there is no minimum clearance as there is at other times, so if you really felt like a daredevil you could reach out and touch a low-hanging &quot;popcorn cloud&quot; with your wingtip. This term is often used in situations where vertical separation minima from clouds is not practical (to stay 500 feet underneath a VMC-friendly cloud layer would require altitudes as low as 500 feet AGL; there are a lot of hazards to navigation at that height from radio antennae to city skylines)&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-17T20:06:23.880" LastActivityDate="2015-07-17T20:06:23.880" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16980" PostTypeId="1" CreationDate="2015-07-17T17:47:46.010" Score="4" ViewCount="1028" Body="&lt;p&gt;What are currently the largest issues with purely electric commercial aircraft (large scale ones like the size of a Boeing 737)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any organizations right now that are trying to solve those issues?&lt;/p&gt;&#xA;" OwnerUserId="9416" LastEditorUserId="5517" LastEditDate="2016-03-31T19:55:10.800" LastActivityDate="2016-11-25T19:55:11.793" Title="What are the hurdles to overcome before purely electric commercial aircraft can fly?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;electrical-system&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16981" PostTypeId="2" ParentId="3513" CreationDate="2015-07-17T17:58:45.247" Score="7" Body="&lt;p&gt;Well, some do. Meet the Marchetti SF.260TP:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j87TD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a very popular light single for aerobatics, which has also seen military use in CAS and observation roles. If you're a Bond fan, you'll know about this one; it appeared in Quantum of Solace. Other turboprops in the small single-engine class include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Piper Meridian&lt;/li&gt;&#xA;&lt;li&gt;One Aviation Kestrel&lt;/li&gt;&#xA;&lt;li&gt;Pilatus PC-9, PC-12, PC-21&lt;/li&gt;&#xA;&lt;li&gt;Cessna 208 Caravan/Super Cargomaster&lt;/li&gt;&#xA;&lt;li&gt;Epic EW1000, LT&lt;/li&gt;&#xA;&lt;li&gt;Socata TBM850, TBM900&lt;/li&gt;&#xA;&lt;li&gt;Grob G-120TP&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As for why not all small singles are turboprops, the other answers have it; turboprops are less fuel efficient at the low altitudes small single typically fly at (they're great for higher altitudes) and they're a different beast to maintain. They're also more expensive; the Marchetti is about a $1.6 million dollar plane, 3 times the cost of a Piper Archer 235, though not all of that is the engine.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-01-22T11:36:08.450" LastActivityDate="2019-01-22T11:36:08.450" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="16982" PostTypeId="2" ParentId="16980" CreationDate="2015-07-17T18:36:42.860" Score="18" Body="&lt;p&gt;The biggest problem with an all-electric-powered aircraft is the same as those plaguing all-electric cars; our current battery technology has nothing on the energy density of fossil fuels:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.financialsense.com/sites/default/files/users/u242/images/2013/Energy-Density.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;There's just no contest in being able to pack the energy needed to push a plane through the air into a volume and weight compatible with an airliner. Jet fuel is kerosene, which is pretty much right in between gasoline and diesel, while any battery technology we've developed can't even be accurately plotted on the scale of this graph.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-17T18:36:42.860" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16983" PostTypeId="2" ParentId="16957" CreationDate="2015-07-17T18:41:31.663" Score="13" Body="&lt;p&gt;No-one has mentioned jet blast so far.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a jet liner is starting up, taxiing and accelerating along the runway prior to rotation, its exhaust gases are directed to the rear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they were angled downwards, as would be the case with a tail-wheel configuration, the jet blast would rip up the runway and be deflected back at the aircraft itself. This could cause untold damage.&lt;/p&gt;&#xA;" OwnerUserId="9417" LastActivityDate="2015-07-17T18:41:31.663" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="16984" PostTypeId="1" AcceptedAnswerId="16988" CreationDate="2015-07-17T18:51:45.557" Score="38" ViewCount="15260" Body="&lt;p&gt;When landing, crosswinds can be very expensive. They cause go-arounds, diversions to other airfields and even crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently pilots crab in the air to counteract crosswinds and, at the last moment, throw the aircraft around to face directly along the runway. This is a challenging and risky manoeuvre - it can cause asymmetrical stalls and worse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose wheel can already be rotated. If the main gear could also rotate, the plane could land in a crabbed attitude and continue that way along the runway until speed had dropped to taxiing speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How come aircraft don't have this feature?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has been flagged that this question is similar to a previous one, &lt;em&gt;Is the main landing gear of a large airplane designed for sideways (crabbed) touchdowns?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is different. In those cases the landing gear does not actively turn to face in the direction of travel relative to the ground, it is merely designed to cope with the extra stress of hitting the runway obliquely. The allowed angle may be quite small. A swivelling undercarriage would allow for a large angle of crab with no attendant stress to the gear because the wheels would be aligned with the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As pointed out on that other question, this design feature &lt;strong&gt;was&lt;/strong&gt; adopted for the B-52. I am asking what factors persuaded designers to abandon this idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Videos (2) of B-52 landing in this manner&lt;/strong&gt;&#xA;&lt;a href=&quot;http://www.skilledpilots.com/video-this-is-how-a-b-52h-lands-in-a-crosswind-and-stays-completely-sideways-while-deploying-a-parachute-and-slowing-down-on-the-runway/&quot;&gt;http://www.skilledpilots.com/video-this-is-how-a-b-52h-lands-in-a-crosswind-and-stays-completely-sideways-while-deploying-a-parachute-and-slowing-down-on-the-runway/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9417" LastEditorUserId="3386" LastEditDate="2015-12-07T13:11:06.143" LastActivityDate="2019-01-30T01:50:51.693" Title="Why don't modern aircraft have landing gear that can swivel to compensate for crosswinds?" Tags="&lt;landing&gt;&lt;landing-gear&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="16985" PostTypeId="1" AcceptedAnswerId="16987" CreationDate="2015-07-17T19:10:15.177" Score="15" ViewCount="2266" Body="&lt;p&gt;Next week I am flying to an airport and going to have dinner. But I've never stepped out of my aircraft except at my home airport! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I park on their ramp, do I keep the parking brake on? &lt;/p&gt;&#xA;" OwnerUserId="9418" LastEditorUserId="100" LastEditDate="2020-05-06T13:02:52.993" LastActivityDate="2020-05-06T13:02:52.993" Title="Do I Set the Parking Brake On the Ramp?" Tags="&lt;airport&gt;&lt;general-aviation&gt;&lt;ground-operations&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16986" PostTypeId="2" ParentId="16985" CreationDate="2015-07-17T19:25:38.980" Score="4" Body="&lt;p&gt;The only (?) downside to setting the parking brake on is that no one can move the aircraft around if they have to (unless you leave it unlocked too). So if you're leaving it somewhere where other people may need to move it without you, you should leave it off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lots of FBOs will move your aircraft without you for good reasons: to make room for other aircraft, to fuel it, to put it in a hangar, protect it from bad weather, move it out of strong wind and so on. You can just check with the FBO staff what they prefer, assuming there is an FBO there, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's no FBO then the best option is probably to tie down the aircraft in case the wind picks up, with the parking brake on. If there are no tie downs then you really have to leave the brake on because otherwise there's nothing at all stopping the aircraft from moving. And if you regularly fly places with no FBOs and no tie downs then you should probably consider &lt;a href=&quot;http://www.sportys.com/pilotshop/aircraft-supplies/tiedowns.html&quot; rel=&quot;nofollow&quot;&gt;bringing your own&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-17T19:25:38.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16987" PostTypeId="2" ParentId="16985" CreationDate="2015-07-17T19:42:01.647" Score="16" Body="&lt;p&gt;I assume you're talking about a light GA airplane (Cessna/Piper singles or twins).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is &quot;&lt;strong&gt;Maybe, but you probably shouldn't.&lt;/strong&gt;&quot;: The parking brake should only be used for as long as necessary to get wheel chocks in, and should then be released.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aside from making it inconvenient for the local ramp personnel if they need to move/tow your plane, setting the parking brake has a few other downsides which are related to the way the parking brakes work on your typical light aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you set the parking brake you're doing two things:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You are pressurizing the hydraulic lines that run to the plane's brakes.&lt;/li&gt;&#xA;&lt;li&gt;You are doing something to prevent that pressure from bleeding back out.&lt;br&gt;&#xA;(Exactly how you accomplish this varies depending on the plane - the &quot;parking brake&quot; on a Piper Cherokee is a tab that prevents the brake handle from returning to the &quot;released&quot; position, maintaining pressure in the cylinder. I think the Cessna 150 pressurizes and then turns a valve.)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Because of how the parking brake works it has two common failure modes when it's set: Pressure can &lt;em&gt;bleed&lt;/em&gt; out or it can &lt;em&gt;blow&lt;/em&gt; out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bleeding Out&lt;/strong&gt; happens because fittings, seals, hoses, etc. in the brake system aren't perfect. Hydraulic fluid will escape past whatever little opening it can find, and eventually there will be insufficient pressure in the system to keep the aircraft from moving.&lt;br&gt;&#xA;If you happened to be parked on an incline steep enough to get the plane rolling it will then go off on its own down the hill just as if you hadn't set the brake (and you will be very confused when you get back to where you left it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Blowing Out&lt;/strong&gt; typically happens on hot summer days when there aren't many little openings for pressure to leak out through: 5606 Hydraulic Oil (the stuff in the brake lines) expands as it gets warm, and with the parking brake set it doesn't have anywhere to go (it can't get back to the main brake reservoir). If you land at 11:00 (local time), set the parking brake, and go have a nice leisurely lunch there is a good chance that when you return to the plane at 13:00 or 14:00 you will find that the hydraulic fluid in your brake system has blown out of whatever the weakest point in the system is (often the seals on the toe brake cylinders, sometimes around the calipers, occasionally a hose fitting fails).&lt;br&gt;&#xA;This means you're going to have a mess of hydraulic fluid to clean up at best, and at worst if you're on a hill you're in the same situation as above (the plane has gone rolling away), only now there's hydraulic fluid all over as well (sometimes in a little red trail to wherever the plane has wound up).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So bottom line: Try to avoid leaving the parking brake set for extended periods of time, &lt;em&gt;especially&lt;/em&gt; if there might be a temperature increase while it's set.&lt;br&gt;&#xA;Instead bring your chocks with you (if you own your own plane, or even if you're a renter, pick up a set of &quot;travel chocks&quot; - they're right at or just under 1 pound, you won't even notice them) and chock your wheels when you leave the plane. Ramp personnel will be able to spot the chock easily, and they're unlikely to fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally you would also tie the aircraft down if possible, but some ramps don't have tiedowns (and others are bring-your-own-rope).&#xA;&lt;img src=&quot;https://i.stack.imgur.com/649Zv.jpg&quot; alt=&quot;Travel Chocks&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-17T19:42:01.647" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16988" PostTypeId="2" ParentId="16984" CreationDate="2015-07-17T19:58:33.090" Score="41" Body="&lt;p&gt;There is one aircraft I know of that can do exactly what you state, the B-52:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NykHM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This plane has steerable dual-bicycle gear which allows the crew to point the gear along the runway while the fuselage is &quot;crabbed&quot; up to 20* off the runway centerline. AFAIK the gear are slaved to the ILS; you dial in the OBI to a course and the gear will point that way even if the aircraft points differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason this was done is primarily due to the design of the rest of the aircraft. It's a very &quot;dense&quot; design, cramming a lot of weight into a very small package, requiring massive wings and tail just to keep the thing under control at altitude. These surfaces then become huge sails at lower altitudes, and with the high, anhedraled wing arrangement on a relatively low fueselage, there's not much room for error. B-52 pilots often say you have to fly 2 seconds ahead of the plane, it's that slow to react to pilot input. So, classic &quot;de-crabbing&quot; techniques involving a hard rudder with counter-aileron just aren't going to work with a BUFF. You have to land crabbed and correct after touchdown, and on a dry runway that isn't a good idea either with an aircraft of this size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern airliners, for their size, are much easier to maneuver on the whole than the BUFF. Really big ones, like the 747, actually have steerable main gear as well, but AFAIK the 747's mains can only be actively steered on the ground, and because they counter-steer to the nose gear (helps bring the tail around corners; imagine driving something about 4 times longer than an 18-wheeler) they would actually be pointed further off the runway line when de-crabbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Four- and six-wheel main gear systems used on larger airliners (777, 787, A380) actually have a small amount of castering built in; if you watch YouTubes of crosswind landings (&lt;a href=&quot;https://www.youtube.com/watch?v=la-hSjKP2TU&quot; rel=&quot;noreferrer&quot;&gt;there&lt;/a&gt; &lt;a href=&quot;https://www.youtube.com/watch?v=mMvLuUJFHYk&quot; rel=&quot;noreferrer&quot;&gt;are&lt;/a&gt; &lt;a href=&quot;https://www.youtube.com/watch?v=xjWjRJGnY34&quot; rel=&quot;noreferrer&quot;&gt;several&lt;/a&gt;) you'll see that the rear two wheels of each gear touch first and actually twist the entire &quot;truck&quot; into line with the aircraft's actual direction of travel. Then as the plane settles on the gear and the fuselage lines back up with the runway, they'll straighten. Planes with one- and two-wheel main gear don't need this as much (and such a system isn't as effective as the first point of contact of a tire is directly level with the gear strut instead of behind it).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-17T20:49:05.187" LastActivityDate="2015-07-17T20:49:05.187" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="16989" PostTypeId="2" ParentId="16980" CreationDate="2015-07-17T20:01:09.813" Score="2" Body="&lt;p&gt;In addition to the energy density issue as mentioned there is a turn around time issue. The fact is that batteries just don't charge up that fast and any system that allows them to do so is often dangerous to be around. So if you are talking about an airliner (lets say we overcame the weight of the battery issues) it takes about 15-30 minutes to fuel up a 747, there is no way you are going to charge any kind of batter that we currently have today to the same energy potential capacity that fast.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-17T20:01:09.813" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16990" PostTypeId="1" CreationDate="2015-07-17T21:04:14.600" Score="6" ViewCount="967" Body="&lt;p&gt;Re a Part 129 air carrier that is short of co-pilots:  Can a pilot who usually flies in the left seat (B737 aircraft: non-US registry) as the Pilot-in-Command fly in the right seat as the SIC (co-pilot)?&lt;/p&gt;&#xA;" OwnerUserId="9421" LastEditorUserId="167" LastEditDate="2015-07-17T23:08:07.313" LastActivityDate="2015-08-22T16:08:08.510" Title="Can a captain fly in the right seat as SIC under part 129?" Tags="&lt;regulations&gt;&lt;icao&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="16991" PostTypeId="2" ParentId="16990" CreationDate="2015-07-17T21:25:45.410" Score="3" Body="&lt;p&gt;From the regulations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each person acting as a flightcrew member must hold a certificate or&#xA;  license that shows the person's ability to perform duties in&#xA;  connection with the operation of the aircraft. The certificate or&#xA;  license must have been issued or rendered valid by:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The State in which the aircraft is registered; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The State of the Operator, provided that the State of the Operator&#xA;  and the State of Registry have entered into an agreement under Article&#xA;  83bis of the Convention on International Civil Aviation that covers&#xA;  the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since a captain can always fulfill the duties of a first officer, then yes, someone who normally occupies the left seat can occupy the right seat.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-07-17T21:25:45.410" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="16992" PostTypeId="1" AcceptedAnswerId="17012" CreationDate="2015-07-17T23:28:31.133" Score="9" ViewCount="3518" Body="&lt;p&gt;The &quot;captain in the right-hand seat&quot; discussion got me thinking. As of 2013, you need an ATPL to operate any plane operating under Part 121 (as part of an &quot;airline&quot;). Both Captain and FO need this level of license, and new Captains require at least 1000 hours as FO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, all you'd need to fly the same model of plane for hire in any other situation is a CPL and the applicable type rating for the aircraft. Prior to 2013 that was all you needed to be hired as an FO on an airliner and get yoke time towards your ATPL and the left-hand seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, are there still opportunities for a civilian CPL holder to fly large turbofan-powered airframes for a living on his way to an ATPL? My first thought was freight, but cargo planes for FedEx or UPS operate under Part 121, same as American Airlines. The only thing that really leaves is charter flights, which operate under Part 135 and thus &lt;em&gt;may&lt;/em&gt; not require the same stricter regs as a pilot on a scheduled service. But, I don't know how many charter operations are using anything bigger than a narrow-body.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="19" LastEditDate="2015-07-18T07:20:22.360" LastActivityDate="2015-07-19T06:37:02.047" Title="Can you fly an airliner without an ATPL?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="16993" PostTypeId="1" CreationDate="2015-07-18T02:42:50.430" Score="2" ViewCount="1344" Body="&lt;p&gt;For military helicopters such as the Sikorsky UH-60 Black Hawk, what is the typical fatigue life of a helicopter airframe (in cycles and hours) ?&lt;/p&gt;&#xA;" OwnerUserId="9425" LastEditorUserId="1467" LastEditDate="2015-07-18T14:16:26.040" LastActivityDate="2015-07-18T17:22:51.373" Title="What is the typical fatigue life of a helicopter airframe?" Tags="&lt;faa-regulations&gt;&lt;aircraft-design&gt;&lt;safety&gt;&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2015-07-18T21:59:06.170" ContentLicense="CC BY-SA 3.0" />
  <row Id="16994" PostTypeId="1" CreationDate="2015-07-18T03:45:09.697" Score="6" ViewCount="1131" Body="&lt;p&gt;For military helicopters such as the Sikorsky UH-60 Black Hawk:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the typical fatigue life of these helicopter main rotor dynamic components in cycles and hours?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) Main rotor pitch links (aka main rotor push rod)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) Main rotor pitch change horn&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) Main rotor blades&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.helicopterpage.com/html/terms.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helicopter or Rotary Wing Terminology&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/TZGmW.gif&quot; alt=&quot;Main Rotor System of a Helcopter&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9425" LastEditorUserId="5517" LastEditDate="2015-08-10T20:41:29.817" LastActivityDate="2015-08-10T20:41:29.817" Title="For military helicopters, what is the typical fatigue life of the main rotor dynamic components?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="16995" PostTypeId="1" AcceptedAnswerId="16996" CreationDate="2015-07-18T05:17:15.653" Score="34" ViewCount="35204" Body="&lt;p&gt;I was motivated to ask by this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/6312/why-are-airplanes-riveted-and-not-screwed&quot;&gt;Why are airplanes riveted and not screwed?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not welded construction? Is welding these alloys too difficult? I come from a refining background &amp;amp; in a lot of hazardous duties welded construction has become the norm because integrity is easier to guarantee than screws, bolts or rivets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just wondering what's different in aviation? Isn't repair, safety, weight &amp;amp; aerodynamics all better with a welded construction?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2018-11-15T14:18:11.823" Title="Why are planes using rivets &amp; not welded construction?" Tags="&lt;aircraft-design&gt;&lt;aircraft-development&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="16996" PostTypeId="2" ParentId="16995" CreationDate="2015-07-18T06:36:30.587" Score="48" Body="&lt;p&gt;Short answer: High-strength aluminium alloys are tricky to weld correctly. Aluminium is such a fine material for aircraft structures that the need to rivet it is gladly accepted.&lt;/p&gt;&#xA;&lt;p&gt;Two things are important:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;While steel has a temperature range in which it gets more and more runny, aluminium alloys change from solid to liquid within a few degrees. Also, heat conductivity in iron-based alloys is lower than in aluminium, so heating steel locally will keep the surrounding material cooler and more solid compared to aluminium. While welding thin sheets of steel is trivial, it needs &lt;a href=&quot;https://www.youtube.com/watch?v=K3NTAuDjuYA&quot; rel=&quot;noreferrer&quot;&gt;lots of experience in aluminium&lt;/a&gt;. For very thin sheets, special equipment like a water-cooled copper backing on which the aluminium sheets rest, so their back is cooled, are needed. Also, the melting temperature of steel and titanium is high enough for it to glow long before it melts, while aluminium will melt without giving you any optical hint of its temperature.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;High-strength aluminium is produced by &lt;a href=&quot;https://en.wikipedia.org/wiki/Precipitation_hardening&quot; rel=&quot;noreferrer&quot;&gt;progressively aging and precipitation hardening the material&lt;/a&gt;. The &lt;a href=&quot;https://en.wikipedia.org/wiki/2024_aluminium_alloy&quot; rel=&quot;noreferrer&quot;&gt;usual alloys use copper&lt;/a&gt; atoms dispersed through the aluminium matrix which locally distort the atomic lattice and strengthen it. If they are heated and rapidly cooled by welding, the copper distribution would be changed and the material would be weakened around the welding area. To harden the finished structure again is rather impractical in most cases, so riveting is the better alternative.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;A third speciality is the oxide layer on aluminium, which has a higher melting temperature than the base material. You need an AC &lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_tungsten_arc_welding&quot; rel=&quot;noreferrer&quot;&gt;TIG&lt;/a&gt; welder to disrupt the aluminium oxide layer, so your choice of welding techniques is rather limited.&lt;/p&gt;&#xA;&lt;p&gt;Also, riveted structures are easier to inspect and to repair. Most repairs need to remove aircraft structure for access, and a riveted structure is easier to disassemble and to put together again after the repair using slightly thicker rivets.&lt;/p&gt;&#xA;&lt;p&gt;My experience with aluminium welding stopped at 4mm thick sheets; while thicker ones were easy to weld, I never managed to weld thinner ones. You sit in front of your structure and heat the spot where you want to start welding. Watching it through the darkened head screen you wait until the spot under the arc becomes glossy, which signals that the surface has started to melt. Now you need to add your welding wire like crazy to keep the spot from heating more, and get the spot moving. If you fail to do so, a second later you will have a hole under your arc, because the aluminium has molten completely and has fallen away. Doing this with 2mm sheets was a pure exercise in futility for me - the moment the surface became glossy it fell away already.&lt;/p&gt;&#xA;&lt;h2&gt;&lt;/h2&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&lt;p&gt;Thanks to @voretaq7 for sharing the link about friction stir welding in the comments! This is made possible by precise positioning of the parts and a computer-controlled welding head and will see wider application in the future. Eclipse Aerospace claims it helps them to avoid 60% of rivets in their jet aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-19T10:05:02.447" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="16997" PostTypeId="2" ParentId="16993" CreationDate="2015-07-18T06:49:46.640" Score="3" Body="&lt;p&gt;Typical helicopters do not have cycles or hours limits on the non-dynamic components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they are not pressurised, there is no concept of &quot;cycles&quot; and the fuselage is neither stressed, nor subject to the same kinds of forces that airliners are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are inspected on fixed hours cycles and specific types might have areas which are subject to non-destructive testing in accordance with operator, manufacturer or regulatory instructions.  Some, most notably Robinsons, are rebuilt by the manufacturer on hours based cycles and return as new.  However, the fuselage and it's major components are not replaced.  They are inspected and refurbished.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dynamic components are of course lifed but I see that you have a separate question for that.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-07-18T06:49:46.640" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17000" PostTypeId="2" ParentId="16984" CreationDate="2015-07-18T12:25:56.320" Score="9" Body="&lt;p&gt;I think one aspect one might consider in every refinement one adds is the risk of malfunction. In this case, what's the risk that a swiveling  happens when you don't want it to. I suspect that the conventional crabbing procedure might not be so bad once you factor in the additional cost &amp;amp; complexity of a swivel &amp;amp; the risk that the gear swivels when not commanded or swivels not commensurate with the amount needed. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2015-07-18T12:25:56.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17002" PostTypeId="1" AcceptedAnswerId="17008" CreationDate="2015-07-18T14:48:54.920" Score="27" ViewCount="4584" Body="&lt;p&gt;PPL pilots are taught stall recovery by experiencing it first hand with an instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do airline pilots intentionally stall an aircraft during training? Or is it all simulator practice because it's too risky?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="9276" LastEditDate="2015-07-18T22:01:17.330" LastActivityDate="2015-07-18T22:01:17.330" Title="Do airline pilots practice stalls in actual aircraft?" Tags="&lt;airline-operations&gt;&lt;flight-training&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17003" PostTypeId="2" ParentId="17002" CreationDate="2015-07-18T15:32:23.037" Score="13" Body="&lt;p&gt;Usually, training is done in a simulator. Not only are the training maneuvers dangerous, but just from an economic perspective, the time in a simulator is cheaper than putting time on a real aircraft, especially for larger types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, stalls are not always covered in regular training for airline pilots. Simulators do not always accurately model a plane's behavior in this situation. When properly flown, airliners should not be in danger of stalling. &lt;a href=&quot;https://aviation.stackexchange.com/q/11938/1696&quot;&gt;There are also numerous warnings&lt;/a&gt;, and the Airbus fly-by-wire system has an &lt;a href=&quot;http://avherald.com/h?article=47196b94&quot; rel=&quot;nofollow noreferrer&quot;&gt;alpha floor protection&lt;/a&gt; feature that will automatically increase the engine power if the aircraft gets close to stalling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, accidents have shown that &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;even an Airbus can stall&lt;/a&gt;, and pilot error has led to multiple cases of airliners stalling and crashing. The result is that &lt;a href=&quot;http://www.japantimes.co.jp/news/2015/01/12/world/airline-pilots-need-better-training-in-recovery-from-a-stall-some-experts-say/#.Vapu2HXYwbc&quot; rel=&quot;nofollow noreferrer&quot;&gt;pilot training is being changed&lt;/a&gt; to include better training for these situations. This takes time though and whether pilots currently get better training depends on the airline.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-18T16:15:05.147" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17004" PostTypeId="1" CreationDate="2015-07-18T15:49:15.083" Score="7" ViewCount="971" Body="&lt;p&gt;I know that training flying time on large commercial aircraft is awfully expensive but I'm just curious how much training time a typical scheduled passenger airline pilot gets on the real craft these days? In particular I'm motivated by investigation reports that reveal that current simulators may have flaws and shortcomings in realistically simulating some parts of the flight envelope. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure this varies  a lot by pilot, airline etc. so I'm not at all looking for an exact answer, just a approximate figure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. Say, I'm flying on a A-320 or a B-787 commanded by a newly type-certified first-officer, what could be the bare minimum actual flight time (not simulator time) on an A-320 / B-787 that he could have had? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. What is the type-rating process? Does that have no need for flight time? Can you get Type rated with 100% sim time on type?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="64" LastEditDate="2016-07-07T21:05:42.260" LastActivityDate="2016-07-07T21:05:42.260" Title="What is the ratio of actual flight time to simulator time on type for airline pilot training?" Tags="&lt;airline-operations&gt;&lt;flight-training&gt;&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17005" PostTypeId="2" ParentId="16993" CreationDate="2015-07-18T17:22:51.373" Score="0" Body="&lt;p&gt;The &lt;a href=&quot;http://www.robinsonheli.com/manuals/r22_mm/r22_mm_3.pdf&quot; rel=&quot;nofollow&quot;&gt;Robinson R-22 and R-44 helicopters are life limited &lt;/a&gt; to 2,200 hours or 12 years:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The complete airframe, including rotor systems, drive system, control system, and fuselage, must be overhauled as instructed by Robinson Helicopter Company when any of the following occur:&#xA;  1. When the helicopter has been operated for 2200 hours since new or since last overhaul&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-18T17:22:51.373" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17007" PostTypeId="2" ParentId="17004" CreationDate="2015-07-18T18:45:26.097" Score="10" Body="&lt;p&gt;&lt;strong&gt;Zero&lt;/strong&gt; hours in type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first time a new FO flies the actual airplane could be their first revenue flight with a training captain in the left seat.  Technically, these flights are still considered training, specifically &quot;initial operating experience&quot; (IOE) and a few trips will be flown with training captains before the new FO is released to fly with regular line captains.  IOE is conducted on revenue flights though, so its entirely possible that the before your flight leaves the gate that the FO has exactly 0 hours in type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial training (leading to either a full type or an SIC type) and the upgrade training (full type ride if you only had an SIC type) are 100% in FTD and level D FFS (full flight simulators) and the checkride is in the FFS.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-18T19:06:05.453" LastActivityDate="2015-07-18T19:06:05.453" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="17008" PostTypeId="2" ParentId="17002" CreationDate="2015-07-18T19:43:42.980" Score="35" Body="&lt;p&gt;In 727 and 747-100/200 aircraft and their simulators for the two airlines I flew those aircraft for up to my retirement in 1999, all stall training was done in simulators, never in the actual aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stall training in the sim consisted of slowing (or otherwise loading up the wing) until the stick shaker started. Recovery was accomplished by unloading the wing and then adding power in that order. Whether unloading the wing was accomplished by just relaxing back pressure or by positive forward movement of the control column (or by rolling out of a bank if you were in one) was a judgement call.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically the sim instructor wanted a significant stick shaker warning, not just a quick blip that you immediately stopped. Also, it was considered bad form if, once you stopped the stick shaker, it started again. Obviously that meant you had loaded up the wing again and were moving toward a secondary stall, which was a definite no-no. As I remember, that was more likely to happen if you made the mistake of leading with power rather than first reducing the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every once in awhile someone would want to play a bit and see how the sim reacted to a full stall. As I remember, the sim would just bounce around with a very high sink rate. I never felt its response to a full stall was at all representative of what the actual airplane would do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I experienced the stick shaker in flight in a 747 three times that I remember: once during a test flight in which that was part of the testing, once with a check airman who liked to play, and once on the line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instance on the line was when I was still an f.o., and it was the captain's leg. He had extended the speed brakes for the descent. When he brought the power up for the final approach, he forgot about the speed brakes. The stick shaker came on immediately. He realized what he had done, and retracted them, and the stick shaker stopped.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-07-18T19:43:42.980" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17010" PostTypeId="1" CreationDate="2015-07-18T21:13:40.377" Score="7" ViewCount="546" Body="&lt;p&gt;I am attending flight school for PPL at the moment at a flight school in Italy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next year I will study in Germany. It is possible that I will not have finished the PPL until then. Now theoretically the university is still very near at my home place (3 hours with the car), so I could somehow manage to finish my license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, would it theoretically be possible to continue my license in Germany at another flight school? I can speak Italian, German and English fluently, so language wouldn't be a problem.&lt;/p&gt;&#xA;" OwnerUserId="9427" LastEditorUserId="65" LastEditDate="2015-07-20T13:53:43.420" LastActivityDate="2015-12-08T22:51:02.170" Title="Can I continue school for the PPL in another country in another flight school, if it is still inside EU?" Tags="&lt;easa-regulations&gt;&lt;ppl&gt;&lt;flight-school&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17012" PostTypeId="2" ParentId="16992" CreationDate="2015-07-19T06:37:02.047" Score="8" Body="&lt;p&gt;You don't have to be an ATP to fly an airliner. In fact, you can fly an airliner as a private pilot. John Travolta is the best example I can think of... He has a house right by a private airport and flies his own personal Boeing 707 (with Qantas livery) and another jet aircraft (Gulfstream I think). With any large aircraft like this over 12500 lbs or with turbojet engine(s), a pilot does need a type specific rating to fly such an aircraft as well as needing to be &quot;current&quot; in that type, but may do so as long as current at any certificate &quot;level&quot; of private pilot or above. However, to fly an airliner as a scheduled air carrier pilot, then yes, an ATP is required as this type of flight would not fall under part 91 or part 135 of the FARs, but instead part 121 which requires that all pilots have ATP certificates.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-07-19T06:37:02.047" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17013" PostTypeId="2" ParentId="16995" CreationDate="2015-07-19T09:50:59.923" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Just wondering what's different in aviation? Isn't repair, safety, weight &amp;amp; aerodynamics all better with a welded construction?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I just thought I'd extend with another thing that is used extensively (which you may or not know about since it is less obvious): &lt;strong&gt;Adhesives&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not combining the material in itself like welding, it goes along the same lines but unlike welding generally does not change material properties. Industrial strength adhesives, such as epoxy, can be incredibly strong when applied properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.henkelna.com/us/content_data/232100_LT6240_0511__Aerospace_Product_Selector_Guide_lo_res.pdf&quot; rel=&quot;nofollow&quot;&gt;PDF&lt;/a&gt; from Henkel has a huge range of products as does this &lt;a href=&quot;http://solutions.3m.com/wps/portal/3M/en_US/Aerospace/Aircraft/Products/Product-Catalog/~?N=7577536&amp;amp;rt=r3&quot; rel=&quot;nofollow&quot;&gt;overview&lt;/a&gt; from 3M Aerospace.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-20T07:39:41.697" LastActivityDate="2015-07-20T07:39:41.697" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17014" PostTypeId="2" ParentId="15529" CreationDate="2015-07-19T17:21:41.263" Score="1" Body="&lt;p&gt;There are many downstream companies that provide briefing services and flight plan filing using DTC or CSC DUATS, and the ones using DTC may have some trouble transitioning to another provider of data. My impression is that more of these downstream vendors are with CSC and will not be interrupted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example my company, ENFLIGHT.COM (which provides the time-saving value added service of personal minimums briefing on top of a DUATS briefing) relies on CSC as the back end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed Martin is also heavily promoting interfaces to allow downstream companies to provide value added services on top of flight service data and connectivity. I know a number of companies are developing interfaces to Lockheed, at the very least to avoid having all their eggs in one basket.&lt;/p&gt;&#xA;" OwnerUserId="9437" LastActivityDate="2015-07-19T17:21:41.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17015" PostTypeId="1" CreationDate="2015-07-19T19:11:19.450" Score="7" ViewCount="13772" Body="&lt;p&gt;I have gone through many ICAO and aviation related sites, but I still can not understand the basic difference between annexes and docs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is it?&lt;/p&gt;&#xA;" OwnerUserId="9221" LastEditorUserId="5517" LastEditDate="2015-07-20T16:03:43.350" LastActivityDate="2018-08-28T04:10:32.457" Title="What is the difference between ICAO Annexes and Documents?" Tags="&lt;icao&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17018" PostTypeId="1" CreationDate="2015-07-19T20:39:38.670" Score="3" ViewCount="1330" Body="&lt;p&gt;In describing major airlines, are &quot;point-to-point&quot; and &quot;low-cost&quot; synonymous? Or is this an over-generalization?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-07-19T23:33:49.043" Title="What is the difference between point-to-point and low-cost airlines?" Tags="&lt;airline-operations&gt;&lt;commercial-operations&gt;&lt;low-cost-carrier&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17019" PostTypeId="1" AcceptedAnswerId="17021" CreationDate="2015-07-19T20:48:38.663" Score="18" ViewCount="4403" Body="&lt;p&gt;As you make a turn, an airplane does not naturally straighten itself out (like a car does to some extent). Are ailerons engineered to stay in whatever position they are placed, or is this simply a byproduct of aerodynamics?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2017-01-15T19:58:33.180" Title="Why does the yoke &quot;stick&quot; in a turning position?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;flight-controls&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17020" PostTypeId="2" ParentId="17019" CreationDate="2015-07-19T21:22:17.063" Score="6" Body="&lt;p&gt;It is a byproduct of aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A constant aileron deflection gives a constant roll moment. A constant, non null, roll moment gives an increasing roll rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a turn you want a constant bank angle, not a rate and even less a rate acceleration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To achieve a constant bank angle, once you are in a turn, you only need minimal aileror deflection (the amount depends on the direction of turn if you have an asymmetrical aircraft such a single propeller or a twin with co-rotating engines).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of deflection needed will also be affected by the wing anhedral/dihedral: a dihedral, for example, will give you a roll moment that will tend to level off the aircraft, the ailerons will have to be deflected just enough to balance this moment with an equal and opposite one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To enter and leave a turn you need a larger aileron deflection because you want to change your bank attitude, you want then to have a net non-zero roll moment (for a relatively brief period of time).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-07-19T21:22:17.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17021" PostTypeId="2" ParentId="17019" CreationDate="2015-07-19T21:25:10.490" Score="20" Body="&lt;p&gt;I think it's a little bit of both -- for most aircraft, how they behave in a turn is a byproduct of their designed aerodynamic properties. This question is actually quite complex to answer. Let's assume you're talking about a simple light aircraft, where control surfaces are mechanically linked to the controls that move them -- this ensures that anything you feel is related to what's happening to the plane, and not necessarily to anything more complex (like a fly-by-wire computer, or a hydraulic linkage with some degree of hysteresis). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft turns are divided, by the CAA &amp;amp; FAA at least (see the FAA's Airplane Flying Handbook, &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-2of7.pdf&quot;&gt;Chapter 3&lt;/a&gt;) into three main categories: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Shallow turns (roughly speaking, &amp;lt;20º angle of bank). These tend to become shallower if left alone.&lt;/li&gt;&#xA;&lt;li&gt;Medium turns (roughly speaking, 20º &amp;lt; $\theta$ &amp;lt; 45º angle of bank). These turns tend to be stable without further pilot input. &lt;/li&gt;&#xA;&lt;li&gt;Steep turns ($\theta &amp;gt; 45$º). These tend to become steeper if left alone, sometimes dramatically so.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Let's look at these in a bit more detail, with some explanation as to why these effects occur.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Shallow turns.&lt;/em&gt; &#xA;These tends to become less steep as the turn progresses, and most aircraft have a natural tendency to decrease the angle of bank throughout the turn. This tendency to lessen the angle of bank arises, I believe, entirely as a designed aerodynamic feature of the aircraft to have lateral stability. As shallow angles of bank are essentially a situation that's is but a small perturbation about flying straight and level, it's desirable for the angle of bank to decrease back to zero if left alone. If that isn't the case, the aircraft stability has to be actively maintained by constant manipulation of the control surfaces (which is tiring or impossible for a human). This stability can be achieved through design features, such as (i) the dihedral of the aircraft's wings, (ii) their sweep, and (iii) their height position -- if high, there is an increased degree of lateral stability due to the centre of mass of the aircraft being below the tilted plane of the wings, and, if disturbed slightly, it experiences a force $F\approx mg\sin\theta$ to &quot;pull&quot; the wings back upright again. The sole purpose of any degree of wing dihedral -- the angle they make with the horizontal -- is to improve lateral stability. If a perturbation causes one wing to drop, the resultant (unbalanced) force will produce a sideslip in the direction of the downward wing. In effect this is analogous to &quot;creating&quot; a flow of air in the opposite direction to the slip. This flow of air will strike the lower wing at a greater angle of attack than it strikes the upper wing. The lower wing will thus receive more lift and the airplane will roll back into its neutral position. Many small aircraft have a slight degree of dihedral on the wings. A similar effect occurs with (ii) swept wings -- when a disturbance causes an airplane with swept back wings to slip or drop a wing, the low wing presents its leading edge at an angle that is almost perpendicular to the relative airflow. As a result, the low wing acquires more lift, rises and the airplane is restored to its original attitude. As an aside, you don't really notice you're in a shallow turn, aside from the fact that you're continually applying a little bit of stick and rudder. The $g$-loading is minimal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Medium turns&lt;/em&gt;. &#xA;In this case, the aircraft is in a metastable state -- it will carry on at a constant angle of bank, but a `shove' to either side will result in the bank increasing or decreasing as appropriate. By this point, $\cos\theta\neq1$, and the outer wing is really generating a lot more lift than the other one -- and thus you'd effect the angle of bank to increase, as it pulls the aircraft into the circle. The effects discussed above, however, still apply, and provide an effective restoring force back to the normal attitude. In a medium turn, aircraft are designed to have these forces balanced, and, in practice, you often need little-to-no aileron and almost no rudder to do a coordinated medium turn in a light aircraft. If it's properly trimmed, you can take your hands off the controls and sit there merrily going around in a circle. Depending on your speed, the $g$-loading is apparent, but not great. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Steep turns.&lt;/em&gt;&#xA;By this point, one wing is generating almost no lift, and the other is generating quite a lot. We've gone beyond the designed stability point of a medium turn, and the angle of bank tends to increase as the outward wing pulls the plane of the aircraft towards its axis of turn. This type of turn actively requires pilot input to maintain a constant angle of bank, and, depending upon the speed, it can physically be quite hard work. The $g$-loading of the wings is significant, and, as the stall speed of an aircraft approximately increases as the square-root of the $g$ factor experienced, it's entirely possible to enter an accelerated stall or even a spin here. You notice the angle of bank, and feel the odd attitude of the aircraft. This phenomenon is called the &lt;em&gt;overbanking tendency.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="7499" LastEditorUserId="3504" LastEditDate="2015-07-20T16:29:47.127" LastActivityDate="2015-07-20T16:29:47.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17022" PostTypeId="2" ParentId="17019" CreationDate="2015-07-19T21:29:19.170" Score="9" Body="&lt;p&gt;Aircraft can be designed to be aerodynamically stable around each of its axis: pitch, roll and yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft (except modern fighters) are designed to be aerodynamically stable in pitch (in angle of attack, actually) and yaw. However making the aircraft aerodynamically stable in both yaw and roll causes an uncomfortable &lt;a href=&quot;https://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow&quot;&gt;dutch roll&lt;/a&gt; oscillation. Therefore they are designed to be only slightly stable in roll with the result that without pilot input shallow banks tend to be, slowly, corrected, but larger bank angles increase in time.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="1467" LastEditDate="2015-07-21T09:18:57.210" LastActivityDate="2015-07-21T09:18:57.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17023" PostTypeId="2" ParentId="17015" CreationDate="2015-07-19T21:35:28.373" Score="7" Body="&lt;p&gt;An &lt;strong&gt;Annex&lt;/strong&gt; to the Chicago Convention on International Civil Aviation (which established the ICAO) is adopted by the ICAO Council according to particular voting procedures laid out in Article 90 of the Convention, and is binding upon the signatory States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;strong&gt;ICAO document&lt;/strong&gt; is just something the ICAO organization has chosen to publish in its Doc Series with an identifying number for ease of reference. Being an &quot;ICAO Document&quot; doesn't in itself say anything about who wrote it or its legal force. For example, Doc 7300 is the Chicago Convention itself, which has a lot of force (but not because it has a Doc number), whereas Doc 9562, &lt;em&gt;Airport Economics Manual&lt;/em&gt; is more informative in nature and tries to be persuasive rather than authoritative.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-07-19T21:35:28.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17024" PostTypeId="1" AcceptedAnswerId="17029" CreationDate="2015-07-19T21:40:04.060" Score="12" ViewCount="6155" Body="&lt;p&gt;Answer for the question &lt;a href=&quot;https://aviation.stackexchange.com/questions/16995/why-are-planes-using-rivets-not-welded-construction&quot;&gt;Why are planes using rivets &amp;amp; not welded construction?&lt;/a&gt; describes why rivets are preferred for joining aluminium alloy components. But how are carbon-fibre-reinforced plastic components in new aircraft joined?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-11-07T05:57:02.027" Title="How are composite materials on aircraft joined?" Tags="&lt;aircraft-design&gt;&lt;aircraft-development&gt;&lt;aerospace-materials&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17025" PostTypeId="2" ParentId="17019" CreationDate="2015-07-19T21:42:28.313" Score="14" Body="&lt;p&gt;All control surfaces are designed to return to a neutral position if no control force is applied. This is part of the certification requirements for every aircraft. JAR 23.177(d) reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In straight, steady sideslips at 1·2 VS1 for any landing gear and flap&#xA;  positions and for any symmetrical power conditions up to 50% of&#xA;  maximum continuous power, the aileron and rudder control movements and&#xA;  forces must increase steadily (but not necessarily in constant&#xA;  proportion) as the angle of sideslip is increased up to the maximum&#xA;  appropriate to the type of aeroplane. At larger sideslip angles up to&#xA;  the angle at which full rudder or aileron control is used or a control&#xA;  force limit contained in JAR 23.143 is reached, the aileron and rudder&#xA;  control movements and forces must not reverse as the angle of sideslip&#xA;  is increased. (…)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that if you keep ailerons in a deflected position, the aircraft will pick up roll speed until an &lt;a href=&quot;https://aviation.stackexchange.com/questions/7734/how-can-i-calculate-the-rolling-moment-of-an-aileron-for-a-given-plane-based-on/7737#7737&quot;&gt;equilibrium with roll damping is reached&lt;/a&gt;. In order to maintain a desired bank angle, the pilot has to actively stop the rolling motion by deflecting the ailerons briefly against the roll. This is different from steering a car where the steering angle is proportional to the turn rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the ailerons are hinged close to their forward edge, the aerodynamic forces will &quot;weathervane&quot; them into the direction of the local flow. By selecting a hinge line and sizing the part of the control surface &lt;a href=&quot;https://en.wikipedia.org/wiki/Balanced_rudder&quot; rel=&quot;nofollow noreferrer&quot;&gt;ahead of the hinge line&lt;/a&gt;, the aircraft designer can tailor the control forces so they are positive at all speeds, but low enough to not tire the pilot. Many &lt;a href=&quot;https://aviation.stackexchange.com/questions/15673/what-is-the-working-principle-of-trim-tabs-on-the-elevators/15674#15674&quot;&gt;ingenious&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Servo_tab&quot; rel=&quot;nofollow noreferrer&quot;&gt;solutions&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_surfaces#Control_horn&quot; rel=&quot;nofollow noreferrer&quot;&gt;have&lt;/a&gt; &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1938/naca-tn-653.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;been&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/1000/what-makes-the-ailerons-on-an-aerobatic-airplane-different-than-the-ailerons-on/1085#1085&quot;&gt;tried&lt;/a&gt; especially for ailerons, and only the application of hydraulics has let this art form within the field of engineering wither in the last decades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't get me started on how exactly you can tailor roll stick forces - this will be a post which will be much longer than anything I have written here before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How and why an aircraft can or cannot right itself up when flying a turn is discussed at length in &lt;a href=&quot;https://aviation.stackexchange.com/questions/12515/could-a-plane-be-constructed-to-be-fly-in-fixed-stick-roll-stable-circles&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-19T22:06:10.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17026" PostTypeId="2" ParentId="17018" CreationDate="2015-07-19T21:47:53.120" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the difference between point-to-point and low-cost airlines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Point to point&lt;/strong&gt; describes an airline that focuses on delivering services without a connecting hub. This cannot be said to imply low cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A independent airline flying between some islands and not offering connections would fall into this category as much as Ryanair, Easyjet or Spirit Airlines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low Cost&lt;/strong&gt; generally implies a point-to-point operation. They structure their business model around filling aircraft on high-demand routes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasons for this: The cost and complexity of handling and organising hubs and connecting flights violates their carefully controlled profit margins and structure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence IMHO you can normally assume a low-cost operation will be a point-to-point operation, but not the other way around.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-19T23:33:49.043" LastActivityDate="2015-07-19T23:33:49.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17028" PostTypeId="2" ParentId="16957" CreationDate="2015-07-19T22:43:16.007" Score="1" Body="&lt;p&gt;Every answer has some key points as to why airliners today &lt;strong&gt;SHOULDN'T&lt;/strong&gt; have conventional landing gear... but it &lt;strong&gt;could&lt;/strong&gt; be done despite the angle of the aircraft while on the ground (for loading/unloading cargo/passengers) or the drag, or the forward visibility while taxiing, or prop clearance (which wouldn't matter if we're talking about modern jet airliner designs)...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting aside safety concerns (prop clearance, stability, etc.) Comfort, loading and unloading concerns, practicality, expenses... Only focusing on why a modern airliner &lt;strong&gt;can't&lt;/strong&gt; have a conventional landing gear... there is no physical reason, to my knowledge, as to why a modern airliner can't be configured as a tail-dragger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest reason why a modern airliner &lt;strong&gt;SHOULDN'T&lt;/strong&gt; be configured this way... (which is a completely different question than why it &lt;strong&gt;CAN'T&lt;/strong&gt;) would have to be the fact that the jet engines would need to be inline with the fuselage which means that until the tail of the aircraft generates enough lift to raise the tail (making the aircraft level with the ground) the jet engines thrust would be directed towards the ground and with jet engines becoming more and more powerful, this could cause a lot of damage to airport infrastructure and the aircraft itself and would put ground crews in an even more &quot;danger close&quot; proximity to the jet blast...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd also venture to say that it may become pretty unstable before it could reach rotation speeds (V1), and I have to wonder how the jet engines would effect the rest of the aircraft when they are spooled up to full power while the tail is still on the ground... I can imagine the engines wanting to stress the engine mounts to the point of some sort of failure whether the engines detach completely or twist the frame of the wings and/or fuselage, maybe even make the aircraft jump off of the ground or even flipping it over and in any case... causing the aircraft to become incapable of sustaining stable flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These factors, and more, make a conventional gear configuration completely invalid for a modern airliner. It could be done with enough capital for research and development that would have to change every preexisting design concept to date... reinventing the modern airliner to be something entirely different all together if it were to ever see flight while maintaining the standards and requirements (safety, performance, efficiency, production and operating costs... etc.) that our existing airliners must meet before being put on the market while being cost effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for reading!&lt;/p&gt;&#xA;" OwnerUserId="9441" LastActivityDate="2015-07-19T22:43:16.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17029" PostTypeId="2" ParentId="17024" CreationDate="2015-07-20T06:50:57.810" Score="19" Body="&lt;p&gt;Ideally, fiber composites are bonded and connected by a &lt;a href=&quot;https://en.wikipedia.org/wiki/Scarf_joint&quot; rel=&quot;nofollow noreferrer&quot;&gt;scarf joint&lt;/a&gt;. The scarf ratio is determined by the ratio of &lt;a href=&quot;https://en.wikipedia.org/wiki/Ultimate_tensile_strength&quot; rel=&quot;nofollow noreferrer&quot;&gt;fiber tensile strength&lt;/a&gt; and the shear strength of the resin. If your fiber takes 3000 N/mm², the resin transmits 20 N/mm² and the fiber content is 60%, the ratio is 1:90, so a 1 mm thick composite layer would need to be joined over a length of 90 mm. In reality, such a ratio is impractical to achieve, so lap joints are used when accepted by the certification authorities. This is the case for for composite gliders, where you will find both scarf and lap joints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the early days of powered composite aircraft, fiber composites were seen with the experience of aluminium in mind, and treated with the same methods. Therefore, the &lt;a href=&quot;https://en.wikipedia.org/wiki/LearAvia_Lear_Fan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lear Fan&lt;/a&gt; and its contemporaries had to use rivet joints throughout the structure. The idea was that by riveting the airframe could be more easily disassembled for inspection and repairs. Riveting carbon fiber composites is quite problematic: You need to use expensive titanium fasteners because aluminium rivets would quickly corrode when in electrical contact to the electrochemically much nobler carbon fibers. Drilling and countersinking holes cuts the very fibers which you try to connect, so you have to double up on wall thickness what is destroyed by the riveting. But the FAA still insisted on rivets - even stringers on panels were riveted, when bonding would had been the most sensible solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft engineers have an expression for composites that are treated like metal: Black Aluminum. The LearFan was pure Black Aluminum. Many of the engineers in this project ended up with Beech when they produced the &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Starship&quot; rel=&quot;nofollow noreferrer&quot;&gt;Starship&lt;/a&gt;, so many of the same techniques were transferred as well. At least, the Starship had a fuselage shell which was laid up on a mandrel and then cut just aft of the cockpit section to get the mandrel out. The splicing of the two fuselage sections was then done by a tapered lap joint; if you want, a practical way of making a not-quite scarf joint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today we have a new generation of engineers who slowly accept that the nature of composite structures requires their own methods of treatment. But you will still find riveted joints even in modern composites structures. Old habits are hard to break.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good reason for riveting is to avoid peeling at the edges of a bonded joint. Engineers with no experience rivet their composites, once they gain some experience they switch to bonding and with lots of experience they add rivets again.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-11-07T05:57:02.027" LastActivityDate="2019-11-07T05:57:02.027" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="17030" PostTypeId="1" CreationDate="2015-07-20T07:40:02.540" Score="11" ViewCount="2587" Body="&lt;p&gt;While I was searching for a listing of aircraft with different anti-/de-icing methods - especially for electro-thermal wing anti-ice - I couldn't find any information about other aircraft except the B787.&#xA;Is there any reason, why other methods like TKS or using bleed air were prefered in the past? &#xA;Are there any studies related to the pro's and con's of the different anti-/de-icing systems?&lt;/p&gt;&#xA;" OwnerUserId="9444" LastEditorUserId="7532" LastEditDate="2015-11-17T04:12:40.273" LastActivityDate="2019-08-29T13:02:13.530" Title="Why is the B787 one of the few aircraft with electro-thermal wing anti-/de-icing?" Tags="&lt;aircraft-design&gt;&lt;anti-ice&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17031" PostTypeId="2" ParentId="17030" CreationDate="2015-07-20T07:51:57.613" Score="14" Body="&lt;p&gt;Partially because 787 has no bleed air available for any purpose. Its engines do not draw bleed air traditionally. Any pneumatic system draws air from other pumps. Hence electro-thermal wing anti-ice system is needed since no bleed air is available.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="1696" LastEditDate="2015-11-18T16:13:25.253" LastActivityDate="2015-11-18T16:13:25.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17032" PostTypeId="1" AcceptedAnswerId="17035" CreationDate="2015-07-20T08:10:19.580" Score="8" ViewCount="1655" Body="&lt;p&gt;Some background: I am not a pilot, but a researcher studying air-flow across mountain terrain using Computational Fluid Dynamics (CFD). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During my studies, I have been particularly interested by high-altitude ridges (2 to 3000m a.s.l., say 10000 ft) that are exposed to regional winds that are generally across the ridge. I have been seeing very interesting turbulence patterns above, and in the lee of the ridges (rotors).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the question: what instructions are given to pilots needing to cross such a ridge at low heights above the terrain, in either direction relative to the wind? What does common sense dictate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am naturally thinking mostly of helicopter pilots doing mountain work, but any other aircraft are very welcome (fire-fighters, ULMs ...). &lt;/p&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="19" LastEditDate="2016-07-14T08:28:41.427" LastActivityDate="2016-07-14T17:43:31.170" Title="When crossing a mountain ridge at low height above terrain what consideration is given to turbulence?" Tags="&lt;turbulence&gt;&lt;mountain-flying&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17033" PostTypeId="1" AcceptedAnswerId="17034" CreationDate="2015-07-20T08:14:59.010" Score="8" ViewCount="810" Body="&lt;p&gt;Even though it is nine years since then, I can still clearly recall my return flight from London Luton to Katowice (Poland), that I took on July 31, 2006 evening. There were a huge, strong storm front coming to Poland (ten days of extremely high warmth followed by ten days of an unusually high raining and really strong stroms, that started on August 1, 2006 in Poland), that we hit somewhere over Germany (hit or flown somewhere around / near it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was then and I am now a layman in aviation, so my description and terms used my not be correct, however I recall, that it was really a bumpy ride. Plane was falling down (loosing 100 ft or so) and trying to  go back to previous altitude etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point, one of a pilots informed everyone on board, that they'll be dimming all the cabin lights, because &quot;&lt;em&gt;they need &lt;strong&gt;more power to the engines&lt;/strong&gt; to go through this strom&lt;/em&gt;&quot;. And soon after that, they really did that and for about 10-20 minutes we were flying in a very limited cabin lightning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true, what we have heard nine years ago? Were cabin lights really consuming that much power back in 2006? Or was that just a strange way pilots wanted us to get a little bit more scared?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was flying with Wizzair, so I assume, that it was A320. There is a &lt;a href=&quot;https://aviation.stackexchange.com/a/15141/3230&quot;&gt;similar answer&lt;/a&gt; on similar matter, but it says about LED-based cabin lights system and I can hardly believe, they were introduced to &quot;cheap&quot; Wizzair's A320s back in 2006.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, even assuming, that our plane was fitted with a &quot;typical&quot; lights, much more energy consuming that LEDs, it is really hard for me to believe, that cutting on cabin lights could bring any &lt;strong&gt;noticeable power&lt;/strong&gt; to airplane's engines. Correct me, if I'm wrong.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-20T08:38:25.840" Title="Were cabin lights really consuming that much power back in 2006?" Tags="&lt;jet-engine&gt;&lt;cabin-design&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17034" PostTypeId="2" ParentId="17033" CreationDate="2015-07-20T08:38:25.840" Score="7" Body="&lt;p&gt;Thunderstorms normally mean icing conditions, which necessitates anti-ice, both through bleed air and electrical systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can see this going a few ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot is (for instance) at high altitude and really does need the additional bit of power to cross above the thunderstorm.&lt;/li&gt;&#xA;&lt;li&gt;Pilot has flown aircraft type where this is a legitimate problem and figures 'why not?' for safety sake.&lt;/li&gt;&#xA;&lt;li&gt;Could be something about motion sickness in the storm, since closing your eyes can be an effective countermeasure. Perhaps dimming the lights goes along the same lines.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-07-20T08:38:25.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17035" PostTypeId="2" ParentId="17032" CreationDate="2015-07-20T09:16:00.973" Score="5" Body="&lt;p&gt;From an older &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/tips_on_mountain_flying.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Publication&lt;/a&gt; on mountain flying:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Mountain Wave&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;When the wind speed is above about 25 knots and flowing perpendicular to the ridge lines, the air flow can form waves, much like water flowing over rocks in a stream bed. The waves form down wind from the ridge line and will be composed of very strong up and down drafts, plus dangerous rotor action under the crests of the waves. If enough moisture is present, lenticular clouds can form to give a visual indication of the wave action. These clouds are reported in the remarks section of hourly sequence reports as ACSL (altocumulus standing lenticular) or CCSL (cirrocumulus standing lenticular)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Pretty much sums up what you're seeing I guess. As for action:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Ridge and Pass Crossing&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;On most mountain flights, you will need to cross at least one ridge or pass. Experienced pilots recommend crossing a ridge or pass at the ridge elevation plus at least 1,000 feet. If the winds at mountain top level are above 20 knots, increase that to 2,000 feet. Plan to be at that altitude at least three miles before reaching the ridge and stay at that altitude until at least three miles past it. This clearance zone will give you a reasonable safety zone to avoid the most severe turbulence and down drafts in windy conditions.&lt;/p&gt;&#xA;&lt;p&gt;If conditions or airplane performance dictate, you may need to fly along the windward side of a ridge to find updrafts for gaining altitude before crossing a ridge. You may also need to circle before reaching the ridge if climbing out of a valley airport. When you actually cross a ridge, you should do so at a 45• angle to the ridge. This allows you to turn away from the ridge quicker if you encounter a severe downdraft or turbulence. Once you have crossed the ridge, turn directly away from it at a go• angle to get away from the most likely area of turbulence quickly. Plan your crossing to give yourself the ability to turn toward lower terrain&#xA;quickly if necessary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As for helicopter mountain flying specifically, I'm afraid you are unlikely to find somebody on here with that experience. You might have better chance on searching for it online and phoning up flight schools that offer such courses (I found a few in the states) for information.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-20T09:33:07.873" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17036" PostTypeId="1" AcceptedAnswerId="17037" CreationDate="2015-07-20T11:31:11.817" Score="-1" ViewCount="171" Body="&lt;p&gt;See the &lt;a href=&quot;https://www.google.com/search?biw=1366&amp;amp;bih=667&amp;amp;tbm=isch&amp;amp;sa=1&amp;amp;q=+paper+airplane+100+feet&amp;amp;oq=+paper+airplane+100+feet&amp;amp;gs_l=img.3..0i24.16271.21620.0.21795.15.12.0.1.1.0.1083.1433.3-1j7-1.2.0....0...1c.1.64.img..12.3.1435.Iw7BTBNa-zQ&quot; rel=&quot;nofollow&quot;&gt;images&lt;/a&gt; of several of the best paper-planes. Notice that their wings are slightly elevated, than a normal paper-plane. That is just what happens with me as well, a little elevation on the wings of a paper-plane makes it go faster and farther. Why does this happens?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-07-20T21:59:07.033" Title="Why does a slight elevation on the wings of a paper plane makes it go farther?" Tags="&lt;lift&gt;&lt;paper-airplane&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-07-21T18:11:24.583" ContentLicense="CC BY-SA 3.0" />
  <row Id="17037" PostTypeId="2" ParentId="17036" CreationDate="2015-07-20T12:27:50.910" Score="3" Body="&lt;p&gt;Most paper planes are nose-heavy and for a very good reason. Basic aerodynamics tells us that putting the centre of gravity forward of the centre of lift, makes any plane (paper or not) more longitudinally stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trade-off is that this configuration tends to cause a nosedive. The trailing-edge elevation counteracts this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, for the very same reason, all conventional-configuration self-stable aircraft are designed with negative tail-lift. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Aside&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A not unheard-of cause of air accident for small commercial planes is&#xA;  pilots ignoring the loading specifications in order to please a&#xA;  customer. If the positioning of the load puts the C of G too far back, the plane becomes unstable. This may result in an unrecoverable spin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9417" LastEditorUserId="9417" LastEditDate="2015-07-20T21:59:07.033" LastActivityDate="2015-07-20T21:59:07.033" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17038" PostTypeId="1" AcceptedAnswerId="17040" CreationDate="2015-07-20T12:28:19.683" Score="9" ViewCount="2290" Body="&lt;p&gt;I live next to HTDA Julius Nyerere International Airport and I do occasionally see Airborne debris, mostly plastic bags flying around at 1000 or more feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How dangerous can this be?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-07-20T13:45:26.950" Title="How dangerous is airborne debris?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17039" PostTypeId="2" ParentId="17038" CreationDate="2015-07-20T13:36:29.863" Score="3" Body="&lt;p&gt;I would say not much. Aircraft are designed to survive collision with small bird and plastic bags are lighter than that. A plastic bag probably won't even visibly damage the skin and if ingested in an engine, it will burn quickly and likely without noticeable impact on the engine performance. The only issue I can think of is if it gets stuck on some important sensor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has been &lt;a href=&quot;http://avherald.com/h?article=4694c940&quot; rel=&quot;nofollow&quot;&gt;an incident&lt;/a&gt; where aircraft collided with some kind of banner hanging from a hot air balloon which clogged pitot tubes and caused airspeed indicators, and auto-flight systems that need them, to fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unreliable airspeed should not be a big deal with proper crew training, but the way that crew mismanaged the situation shows there is some risk. However plastic bags are smaller than the banner in that incident, so the chance of one hitting one of the three critical spots on the aircraft is quite low.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-20T13:36:29.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17040" PostTypeId="2" ParentId="17038" CreationDate="2015-07-20T13:45:26.950" Score="8" Body="&lt;p&gt;The FAA's &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5210_24.pdf&quot;&gt;advisory circular&lt;/a&gt; on &lt;em&gt;Airport Foreign Object Debris (FOD) Managament&lt;/em&gt; mentions plastic bags and other trash as a type of FOD and says these are the dangers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;FOD Hazards.&lt;/strong&gt;   FOD can severely injure airport or  air carrier personnel or damage  equipment.  Types of potential damage include: cutting aircraft tires; being  ingested into engines;  or becoming&#xA;  lodged in mechanisms affecting flight  operations.  Personnel injuries&#xA;  or even death  can occur when jet blast propels FOD through the&#xA;  airport environment at high velocities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since you're asking specifically about airborne items, that would mean the most likely dangers from that list are engine ingestion or &quot;becoming lodged in mechanisms affecting flight operations&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main issue with a plastic bag seems to be that it damages the engine, rather than stopping it entirely. &lt;a href=&quot;http://www.academia.edu/12116945/Aviation_Engine_Damage_Evaluation&quot;&gt;This paper&lt;/a&gt; recommends an inspection if any &quot;soft material&quot; (including plastic bags) are ingested:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Remains on impellers and/or LP diffuser exit ducts confirm a bird or soft material has passed through the Engine and possibly&#xA;  contaminated the secondary air system, fuel nozzle and HP turbine vane&#xA;  cooling air passages.&lt;/li&gt;&#xA;  &lt;li&gt;If contamination occurs, hot section components deteriorate rapidly, increasing the cost of refurbishment. Therefore, operators are&#xA;  recommended to carry out a hot section inspection (HSI) as soon as&#xA;  possible after a bird strike or ingestion of soft material is&#xA;  confirmed&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for affecting flight instruments, the main danger is probably that the bag covers the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot_tube&quot;&gt;pitot tube&lt;/a&gt;, resulting in false airspeed readings. That &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;can be catastrophic&lt;/a&gt; if the pilots don't realize what's going on, but many larger aircraft have multiple pitot tubes so it would probably need a lot of plastic bags (or a lot of bad luck) to cause an accident. And a bag stuck on the windscreen could block a pilot's view but if there are two pilots then that shouldn't be critical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, all of the above applies to airliners. If you fly a light piston single through airborne debris the results could be worse because of the lack of technical (and perhaps crew) redundancy.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-20T13:45:26.950" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17041" PostTypeId="1" AcceptedAnswerId="17042" CreationDate="2015-07-20T15:44:24.117" Score="9" ViewCount="12902" Body="&lt;p&gt;If a 35 year-old pilot were issued a 1st class medical on January 15, 2012, am I correct that that pilot would be able to exercise privileges requiring a 1st class medical until January 15, 2013? Or would they extend until January 31, 2013? The chart in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2766b8a7c241f67946e3d8e92ffd7d9a&amp;amp;node=14:2.0.1.1.2.1.1.17&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.23&lt;/a&gt; mentions something about it expiring on the last day, but I can't find that exact language anywhere but in the header row of the reference table.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, after the 1st class medical certificate expires, does it not afford the pilot the privileges of a 2nd class medical for the 60 months listed in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2766b8a7c241f67946e3d8e92ffd7d9a&amp;amp;node=14:2.0.1.1.2.1.1.17&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.23&lt;/a&gt;? I'm looking for the part of the FAR that explains how medical certificates of a higher class afford the privileges of a lower class after their original designation period expires.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-07-23T05:46:29.007" LastActivityDate="2019-01-01T20:23:50.877" Title="Does my 1st class medical give me 2nd and 3rd class medical privileges after it expires?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17042" PostTypeId="2" ParentId="17041" CreationDate="2015-07-20T16:24:44.533" Score="14" Body="&lt;p&gt;A first class medical issued to a 35 year old pilot on 15 Jan 2012 will let that pilot:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;exercise privileges of an ATP certificate until 23:59 31 Jan 2013&lt;/li&gt;&#xA;&lt;li&gt;exercise privileges of a commercial certificate until 23:59 31 Jan 2013&lt;/li&gt;&#xA;&lt;li&gt;exercise privileges of a private, recreational, student or CFI certificate (if the CFI is acting PIC) until 23:59 31 Jan 2017&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Your first class medical is always a first class medical -- you don't get private pilot privileges for 5 years because a first class medical grants third class privileges, rather you get private pilot privileges for 5 years because that is what a first class medical grants you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These durations are from the table of 61.23 (d).  You don't see this language in the text above the table because they are not concerned with the duration of the privileges but only the minimum required medical class for specific operations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, 61.23 (a)(2)(ii) says you must hold &lt;em&gt;at least&lt;/em&gt; a second class medical to exercise the privileges of a commercial certificate and 61.23(d)(1)(iii) and 61.23(d)(2)(i) list the duration that each of an first and second class medical can be used to for this purpose. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-20T16:33:24.460" LastActivityDate="2015-07-20T16:33:24.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17043" PostTypeId="2" ParentId="17041" CreationDate="2015-07-20T16:25:16.817" Score="2" Body="&lt;p&gt;I'm a bit unsure what you're looking for, because the answers to your questions are all in the table that you already found. But anyway, the medical would expire for first-class use on Jan 31 2013. The language is in the table header, as you already noted (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Then your medical certificate expires, for that operation, &lt;strong&gt;at the end&#xA;  of the last day of the 12th month&lt;/strong&gt; after the month of the date of examination shown on the medical certificate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For second-class privileges - by which I assume you mean commercial pilot privileges - the medical would also expire on Jan 31 2013, as per the third row in the table, which covers these privileges:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a commercial pilot certificate or an air traffic control tower&#xA;  operator certificate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The only way you can use it for 60 months is for the following privileges:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a recreational pilot certificate, a private pilot certificate, a&#xA;  flight instructor certificate (when acting as pilot in command or a&#xA;  required pilot flight crewmember in operations other than glider or&#xA;  balloon), a student pilot certificate, or a sport pilot certificate&#xA;  (when not using a U.S. driver's license as medical qualification)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-20T16:25:16.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17044" PostTypeId="1" CreationDate="2015-07-20T16:48:13.567" Score="5" ViewCount="717" Body="&lt;p&gt;Due to the more acute nose down attitude of a turboprop on approach, does this make it less difficult to control compared to the relatively high nose up attitude of a jet?&lt;/p&gt;&#xA;" OwnerUserId="8383" LastEditorUserId="1467" LastEditDate="2015-10-05T18:08:02.537" LastActivityDate="2015-10-05T18:08:02.537" Title="Does the nose-up attitude of a jet make it more difficult to land than a turboprop?" Tags="&lt;landing&gt;&lt;turboprop&gt;&lt;attitude&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17045" PostTypeId="1" AcceptedAnswerId="17050" CreationDate="2015-07-20T18:17:21.047" Score="11" ViewCount="1030" Body="&lt;p&gt;In a comment to a question about setting the parking brake, @rbp said to just get a set of wheel chocks and use those instead. I was piqued - it never occurred to me you'd need your own, I thought they'd be littered around the tarmac for common use - and did a quick Google Shopping search for &quot;aircraft chocks&quot;. I was surprised to see a wide price variance, even within a subset of relatively small-size chocks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, &lt;a href=&quot;http://www.northerntool.com/shop/tools/product_200594352_200594352?&quot;&gt;here is a pair&lt;/a&gt; of 10&quot; rubber chocks with 3ft rope, about 15 lbs, for \$15. &lt;a href=&quot;http://www.uline.com/Product/Detail/H-4196/Dock-Equipment/Aircraft-Wheel-Chocks-10-x-5-x-4-1-2?&quot;&gt;Here is what looks like exactly the same thing&lt;/a&gt;, for &lt;em&gt;\$98&lt;/em&gt;. Tigerchocks make considerably lighter ones, but they are \$120-ish &lt;em&gt;per chock&lt;/em&gt; (over \$200 for any roped pair) while other lightweight designs are as cheap as \$30 for about the same size. Other designs seem to vary between $20-60 for a roped pair, and have noticeable differences in size and design, but c'mon, they're a wedge you put under the tire to stop the plane rolling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much of this variance is &quot;you get what you pay for&quot; (more money equals a better product in some way; lighter, grippier, more durable etc) and how much of this is &quot;caveat emptor&quot; (the aviation crowd are used to paying a lot for their gear, so some yahoo with an MBA says &quot;let's see how much we can milk them for a pair of rubber blocks tied with a rope&quot;)?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2015-07-21T03:37:29.137" LastActivityDate="2015-07-21T03:37:29.137" Title="Chocks - why the wide variances in price?" Tags="&lt;cost&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17046" PostTypeId="2" ParentId="17015" CreationDate="2015-07-20T18:50:22.253" Score="0" Body="&lt;p&gt;There is no general consensus on the legal bindingness of the Annexes for the member states among jurists (Abeyratne, R., Air Navigation Law, 2012, Springer). It is therefore difficult to establish a difference between ICAO Annexes and Documents.  Deviations from ICAO standards are listed in a country's AIP (Aeronautical Information Publication) in section GEN 1. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a different post on stackexchange suggesting that ICAO's documents (both SARPs and Docs) do not have the force of law: &lt;a href=&quot;https://aviation.stackexchange.com/questions/6298/do-icao-specifications-have-the-force-of-regulation&quot;&gt;Do ICAO specifications have the force of regulation?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this legally boils down to in the different member states, I don't know.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-07-21T21:07:03.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17047" PostTypeId="1" AcceptedAnswerId="17054" CreationDate="2015-07-20T20:02:49.123" Score="13" ViewCount="3509" Body="&lt;p&gt;As a quick follow-up question to &lt;a href=&quot;https://aviation.stackexchange.com/questions/17045/chocks-why-the-wide-variances-in-price&quot;&gt;my earlier one about the retail cost of chocks&lt;/a&gt;, which wheel(s) typically get the chocks on a GA tricycle-gear plane? Do you buy one roped pair for the nose wheel (make sure your chocks are away before starting up), or two pair for the main gear, or all three (I doubt this, especially on a small plane)?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-21T19:08:44.307" Title="Which wheel or wheels get the chocks?" Tags="&lt;equipment&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17048" PostTypeId="2" ParentId="17044" CreationDate="2015-07-20T20:05:09.483" Score="7" Body="&lt;p&gt;You're asking, I think, two questions. The first in the title is very general; the second in the text relates to control as affected by aircraft pitch on the approach. The answers to both are going to be somewhat opinion based as well as depending on which turboprops and which jets you're talking about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My thoughts are based on the following turboprops: King Air A90, Swearingen SA-226 and 227, Fokker F-27; and on the following jets: Cessna Citation 500, Boeing 727-100, and Boeing 747-100/200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinion, there is no general practical difference in the difficulty or ease of approaches and landings based on whether you're in a turboprop or a jet or what your pitch angle on the approach is. Some might say that a nose down attitude is going to give you better visibility. However, I never found that lack of visibility over the nose was a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are differences in the characteristics of turboprops and jets that make the one or the other the better approach and landing vehicle in certain circumstances. For example, if you need a quick descent, you can flatten out the pitch of a turboprop and get a lot of drag, more if you move into beta. For jets, the engines are always going to be producing some forward thrust (although I seem to remember the DC-8 allowed idle reverse in flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a crosswind, the heavier the aircraft and the higher the landing speed, the easier it will be to handle the cross wind, and transport category jets in general are heavier than turboprops. Also, in a crosswind, a high wing is considered a liability, and there are a lot of high wing turboprops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess what I'm saying is that individual aircraft and circumstances outweigh differences between turboprops and jets insofar as approach and landing is concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hardest and easiest aircraft I flew insofar as getting a good touchdown were both jets: the hardest being the 727-100 and easiest the 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most flexible insofar as the approach was concerned were the SA-226/227. You could fly the approach clean at near-jet speeds and then slow down very quickly on short final. KSFO controllers back in the 1980s used to appreciate our ability to fit in. Or they could bring us in on a close-in downwind and then have us dump it for a well-timed turn to base and then a very short final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;---------- Edit for additional information&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@JanHudec pointed out that turboprops have a faster response to power changes than jets. That's true, though in day to day flying, you plan for what you have. Obviously, though, in an emergency situation that required additional power, the turboprop would enjoy the advantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference in response to adding power is not as great as it used to be. As I remember, when the 727 first came out, there were a couple of incidences of 727s touching down slightly short of the runway because of the time required for the engines to spool up. The figure that sticks in my mind is that for those first engines, the time from full idle to full power was 7 seconds. Boeing fixed the problem by putting in a flight idle and a ground idle. The flight idle kept the engines spooled significantly higher than the ground idle. That involved no change to where you placed the thrust levers. You brought them all the way back. If you were still in the air, that wouldn't spool the engines all the way to full idle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 engines reacted very quickly, much more so than the 727 even with the flight idle setting. I remember two instances in the 747 in heavy gusting crosswinds where I used a lot of power at the last moment. In the 727 those touchdowns might have been a lot harder? In a turboprop maybe a little less hard?&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-07-20T22:23:24.653" LastActivityDate="2015-07-20T22:23:24.653" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17049" PostTypeId="2" ParentId="17047" CreationDate="2015-07-20T20:57:04.607" Score="4" Body="&lt;p&gt;Normally, the chocks are put on the main wheels (the wheels under the wings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you just chock the nose wheel and there is no tie down then the aircraft could pivot/rotate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to clarify the situation... At airports there are two main parking areas, the &quot;ramp&quot; and the parking area. Usually there are tiedowns only in the parking area. Also, the parking area is allocated, so you have to get permission to take up a slot there. When you visit an airport short term most crews therefore park on the ramp and chock the wheels. The problem arises that &quot;short term&quot; might turn into hours or overnight. If strong winds develop, then a poorly chocked aircraft can pivot, come loose and roll away.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-07-21T19:08:44.307" LastActivityDate="2015-07-21T19:08:44.307" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17050" PostTypeId="2" ParentId="17045" CreationDate="2015-07-20T20:58:31.283" Score="8" Body="&lt;p&gt;The point of wheel chocks is to prevent the tire from rolling (and thus the aircraft from winding up &quot;somewhere other than where we parked it). The aircraft doesn't know how much we spent on the chocks, and if it did it probably wouldn't care. (OK, it might laugh at you if you buy solid gold bars to chock a Cessna 150.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from pretty obvious quality-related things (a $5 set of chocks made out of cheap rubber that fall apart when you squeeze them in your hand)&#xA;the big reasons for price differences come down to a few things:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Size&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Just like with chocking a car or truck there are various sizes of chocks available, and they vary in length and height:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/zBdTl.png&quot; alt=&quot;Chock sizes&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For very large aircraft very large chocks are used (wider and taller):&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/JGIjs.jpg&quot; alt=&quot;Big chock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;…and for smaller aircraft smaller chocks are used (shorter and narrower):&#xA;&lt;img src=&quot;https://i.stack.imgur.com/tw9nZ.jpg&quot; alt=&quot;Small Chock&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Big chocks require more material, and thus cost more to make than small chocks, so logically they cost more.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Nice Features &amp;amp; Laziness&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I have a set of $20 aluminum wheel chocks. They have a bungee cord that keeps them tight against the tire (so there's no room for the tire to roll), and they weigh just over 1 pound (they're light and small enough to throw in the plane without thinking about it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The guy two planes down from me has a wheel chock made of three sections of 2-by-4 inch lumber, screwed together to be just slightly wider than his tires and painted safety-orange. It probably weighs less than 5 pounds and cost him $10 and a few minutes with a power drill &amp;amp; spraypaint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both work equally well, but I was willing to pay for someone else to cut and bend some aluminum that I can fold up into a small space easily rather than finding a chunk of lumber I didn't need and making my own chock.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;&quot;Standard Aviation Markup&quot;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There's a joke that when trying to determine the price of a component for an aircraft you take the price of that component in a non-aviation application and add some zeros to the end of it.&lt;br&gt;&#xA;That's not a joke in this case: Those two rubber chocks you posted are, for all practical purposes, identical - with the exception of their price. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-20T20:58:31.283" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17052" PostTypeId="1" AcceptedAnswerId="17066" CreationDate="2015-07-20T21:03:44.980" Score="18" ViewCount="4069" Body="&lt;p&gt;The difference between a private and commercial pilot's license hinges on this critical ability to expressly receive pay for flying; a PPL is allowed to fly &quot;in furtherance of a business&quot; but cannot be paid to fly a plane, while a CPL can. That brings up an important question; in today's corporate world, there often isn't a strict &quot;hours for pay&quot; exchange; you get a salary, for which you perform the duties of the job (which do not necessarily mean being there 8 hours a day). So,  what's the difference between being paid &lt;em&gt;while&lt;/em&gt; flying in furtherance of a business, and being paid &lt;em&gt;for&lt;/em&gt; flying?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple example (I hope): I'm a salary man, and my workplace happens to abut a public air park in Dallas. A coworker of mine needs to get to Waco to have a short face-to-face meeting with a client (teleconferencing won't do), and my boss knows I'm a PPL and own a fairly speedy Cherokee 235 (cruising speed 135 mph). The forecast for tomorrow is perfect flying weather, so he proposes this deal; I commute to work in my plane tomorrow instead of driving. After morning coffee and e-mails, my coworker and I will head over to the air park and fly out from there to Waco in my plane and be picked up by the client. We'll have the meeting, be driven back to the airfield, and I'll fly us back to Dallas so he can drive home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this, I'll get paid for the workday as I normally would, no vacation or other leave time required to be used. My boss also suggests that I can expense my fuel costs and any landing fees, like I would be able to do with my gas and parking fees if I drove. My boss gets two people face-to-face with the client faster than if we drove, with less time off our normal duties than if we flew on a regional jet (and &lt;em&gt;much&lt;/em&gt; cheaper), and I get paid to fly my plane without being explicitly hired to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Can I accept the deal at all, or will the fact that I'm technically being paid &lt;em&gt;while&lt;/em&gt; flying be considered the same as being paid &lt;em&gt;for&lt;/em&gt; flying even though no additional money specifically for my yoke time is changing hands?&lt;/li&gt;&#xA;&lt;li&gt;What portion of my out-of-pocket costs can legally be expensed?&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;All my fuel and landing fees incurred between taking off from and landing back at my home field (which I otherwise would not have incurred)?&lt;/li&gt;&#xA;&lt;li&gt;100% of costs from when I take off at the air park near work to when I return there (the portion of the flight in furtherance of the business)?&lt;/li&gt;&#xA;&lt;li&gt;50% of &quot;non-commuter&quot; flight costs (gas to and from Waco and the landing fee there, but not the fees at the air park or gas to and from my home field)?&lt;/li&gt;&#xA;&lt;li&gt;No expenses allowed (because that would be &quot;compensation for flying&quot;)?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Would any of this change if I were an hourly employee doing this &quot;on the clock&quot; as opposed to being salaried?&lt;/li&gt;&#xA;&lt;li&gt;Would any of the above answers change if my boss wanted me to rent a speedier plane (that I was rated for of course)? Would I be able to expense some or all of the rental?&lt;/li&gt;&#xA;&lt;li&gt;I'll try not to make this an off-topic &quot;legal advice&quot; question: if I refused the deal because I thought it would violate the restrictions of my PPL on flying for pay, and I was summarily fired, should I be talking to a lawyer about a wrongful termination suit?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8114" LastEditDate="2018-10-16T16:51:01.013" LastActivityDate="2018-10-16T16:51:01.013" Title="Would this &quot;being paid while flying&quot; scenario be considered &quot;flying for compensation&quot;?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17053" PostTypeId="2" ParentId="17032" CreationDate="2015-07-20T21:08:17.547" Score="-3" Body="&lt;p&gt;Yeah, the instructions are &lt;strong&gt;DON'T GO NEAR ROTORS OR YOU MIGHT DIE&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You never want to pass close over a ridge, even if does not have lenticular cloud or other visible sign of downdraft. Once you get caught in the down draft it can be almost mathematically impossible to escape. My instructor's instructor was killed in Maine by trying to cross a mountain too close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The procedure is to navigate to a valley or pass where you can clear the mountain by a healthy margin.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-20T21:08:17.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17054" PostTypeId="2" ParentId="17047" CreationDate="2015-07-20T21:22:23.093" Score="7" Body="&lt;p&gt;To be most effective chocks should be placed on both of the main gear of light aircraft. This prevents the aircraft from rotating or pivoting about the chocked wheel.&lt;a href=&quot;http://flightsafety.org/amb/amb_jan-feb93.pdf&quot;&gt;There's a nice article from the Flight Safety Foundation&lt;/a&gt; which talks about this.&lt;br&gt;&#xA;The FAA, in an overabundance of caution, advises you to chock ALL the wheels (see &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22573&quot;&gt;AC 20-35C&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Practically speaking, on a flat ramp and a calm day chocking any single wheel is usually enough to keep the airplane where you put it for a short while (say long enough refuel the aircraft, or to get lunch).&lt;br&gt;&#xA;When using a single chock my preference in these cases is to chock the nose wheel as it's the most visible (I fly a low-wing airplane, and an inattentive line person who needs to tow the plane could miss a chock on the main gear). With two chocks the main gear should be secured on each side of the aircraft to keep it from pivoting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For anything longer than that a brief food and fuel stop, or when high winds are anticipated, aircraft should be properly secured (by tying them down and chocking at least one wheel).&lt;br&gt;&#xA;In these cases the tiedowns serve as the primary securing mechanism, and the chocks as a secondary mechanism (keeping the plane from rocking fore and aft in high winds and breaking the tiedown ropes).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note that there is an exception to the &quot;high winds&quot; bit here: If winds strong enough to blow chocks around on the ramp are anticipated, such as a hurricane, the chocks should be removed unless they can be adequately secured to ensure they don't get blown into an aircraft.&lt;br&gt;&#xA;  Of course if winds that strong are anticipated you should really have flown away before they got to you, or you should be looking for a hangar to weather the storm in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-20T21:22:23.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17055" PostTypeId="2" ParentId="16995" CreationDate="2015-07-20T21:27:00.430" Score="3" Body="&lt;p&gt;First of all, most aircraft have many welded components, but they are mostly the frame/structural components. The skin is usually rivetted for two reasons (1) it is much easier to remove or replace a rivetted panel, and (2) the skin-to-structure mating location is in many cases not accessible. In other words, the skin needs to be joined to the frame. That means the welder would have to be able to access that joint. Even if you had access to the joint, it would just be a seam weld, then you would have to weld again on the outer surface to seal the butt joints between panels. Then you would have to grind those seals. Very time consuming and expensive and probably not stronger than rivets anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, consider that airplanes flex constantly while they fly. This will play havoc with welded joints, potentially leading to cracking in a thin joint (which skin joints will be). Rivets are much more friendly to moving parts because they have a little give to them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, you want a lot of surface area for the weld, and with a thin section it is hard to get this. For this reason it would actually be a much better idea to solder or braze the skin on than weld it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All those things being said, it is very possible to design a plane using welded construction similar to a car using what are called &quot;spot welds&quot;. This may yet happen, but the aircraft industry has not got there yet.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-20T21:27:00.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17056" PostTypeId="1" AcceptedAnswerId="17057" CreationDate="2015-07-20T21:42:28.143" Score="12" ViewCount="2887" Body="&lt;p&gt;Is it quiet in the cockpit when flying faster than the speed of sound or is the noise from air resistance just too loud? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar question: is it quieter at the front of an airliner flying faster than the speed of sound because the engines are behind you (comparing to the rear of the plane)?&lt;/p&gt;&#xA;" OwnerUserId="9447" LastActivityDate="2018-07-31T01:29:03.260" Title="Is it quiet in the cockpit when flying faster than the speed of sound?" Tags="&lt;airliner&gt;&lt;airspeed&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17057" PostTypeId="2" ParentId="17056" CreationDate="2015-07-20T22:03:35.433" Score="15" Body="&lt;p&gt;No, for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Speed of sound is always relative to the material the sound propagates in; it moves faster through denser media, such as the aluminum structure of the aircraft itself. The aircraft's structure moves with the aircraft, so the vibrations of the jet engines will be transmitted to the cockpit/cabin at the same speed as when the airplane were flying subsonic.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The air inside the cockpit is still, and so sound within this local bubble is unaffected by the speed of the bubble itself (and so sound can travel faster than sound). If this weren't true then radios and other cockpit sound sources like alarms would be inaudible at supersonic speeds, which would be a major safety hazard and tactical disadvantage to supersonic flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You actually don't even have any significant aural cues inside the cockpit that you've exceeded Mach 1; you have to rely on your airspeed gauge to tell you.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-22T16:04:36.673" LastActivityDate="2015-07-22T16:04:36.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17058" PostTypeId="1" AcceptedAnswerId="17060" CreationDate="2015-07-20T22:19:19.713" Score="7" ViewCount="12636" Body="&lt;p&gt;What is the standard direction for a traffic pattern at an uncontrolled or non-towered airport?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1968" LastEditDate="2015-07-22T16:10:17.557" LastActivityDate="2019-01-28T02:49:34.170" Title="What direction should a traffic pattern be at an uncontrolled or non-towered airport?" Tags="&lt;faa-regulations&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17059" PostTypeId="2" ParentId="17058" CreationDate="2015-07-20T22:55:28.113" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/bc3edee9f4eaa28c86256eeb00519374!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;FAR 91.126(b)(1)&lt;/a&gt; states that all turns in the vicinity of an airport in Class G airspace should be made to the left unless otherwise marked. That includes the traffic pattern.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-07-20T22:55:28.113" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17060" PostTypeId="2" ParentId="17058" CreationDate="2015-07-20T23:04:22.793" Score="11" Body="&lt;p&gt;When aviation literature mentions &quot;&lt;em&gt;the&lt;/em&gt; standard traffic pattern&quot;, it's usually a left-hand counterclockwise pattern; regardless of wind direction, the runway will always be to your left side and you make left turns to follow the pattern through crosswind, downwind and base legs. This is the default pattern direction when there are no overriding signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this is &lt;em&gt;only&lt;/em&gt; the default, and airports are free to change the procedure as needed to comply with local terrain or development. An airfield near a neighborhood to its east, for instance, may require that traffic circle around the west side of the airport; therefore this airfield's 17/35 runway will require a left-hand pattern when using runway 35, but a right-hand pattern when using runway 17. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airfield establishes a non-default traffic pattern, they must provide this information to pilots in a readily-visible manner. The standard recommended (though not required) set of runway and pattern indicators is known as the segmented circle, so called because its most visible identifying feature from a distance is a 75-foot circle of dashed lines:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dgHf7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In the center of the circle as pictured is the runway direction indicator aka the tetrahedron; this will indicate which strip of asphalt to use and which direction to take off and land on it (the narrow end points in the direction that planes should take off and land). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Off to one side is the windsock, which is the only piece of equipment that is required at any airfield; it indicates approximate wind speed and direction. FAA guidelines for the sock say it should reliably turn to the wind direction at 3 knots, begin to inflate at 5 knots and be fully extended at 15. The windsock can replace the tetrahedron in the center of the circle; in that configuration you would simply approach the airfield using the runway closest to the direction in which the tip of the windsock is pointing (if winds are calm and/or the airfield has multiple runways, the tetrahedron is preferable). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the ground just outside the segmented circle are L shapes; these are the pattern indicators, and point in the direction of the base leg when approaching the runway from that end (so if you're following the pattern, the end of the L should be pointing at you before your turn to final).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, the circle in the above picture tells aviators several critical things without any human (or computer) having to relay the information vocally: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The approach direction is from the upper right to the lower left of this picture. &lt;/li&gt;&#xA;&lt;li&gt;The wind is roughly in line with the runway, so no crosswind landing procedure is required.&lt;/li&gt;&#xA;&lt;li&gt;Winds are very strong (the windsock is fully extended which indicates wind speeds in excess of 15 knots) so ground speed will be much lower than IAS at takeoff and landing. &lt;/li&gt;&#xA;&lt;li&gt;Most relevant to your question, airfield traffic should be on a right-hand pattern at this time; if the winds and thus the runway in use were opposite, traffic would use a left-hand approach.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-01-23T22:16:51.503" LastActivityDate="2019-01-23T22:16:51.503" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17061" PostTypeId="1" CreationDate="2015-07-20T23:39:25.983" Score="5" ViewCount="1160" Body="&lt;p&gt;Let's suppose a catastrophic &lt;a href=&quot;https://en.wikipedia.org/wiki/Engine_failure_on_take-off&quot; rel=&quot;noreferrer&quot;&gt;EFATO&lt;/a&gt; has occurred while climbing out of JFK from Runway 31L, the aircraft is at its MTOW and the best option is to set it down in Jamaica Bay. How long would the aeroplane float and what are the chances of surviving?&lt;/p&gt;&#xA;" OwnerUserId="8383" LastEditorUserId="62" LastEditDate="2015-07-21T14:24:39.250" LastActivityDate="2015-07-21T21:52:13.093" Title="What is the probability that passengers can survive a ditching in a 747 at MTOW?" Tags="&lt;emergency&gt;&lt;passenger&gt;&lt;boeing-747&gt;&lt;ditching&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17063" PostTypeId="1" CreationDate="2015-07-20T23:42:57.103" Score="2" ViewCount="609" Body="&lt;p&gt;I am not doing normal ground school (I chose to do it online). I have passed my &lt;a href=&quot;https://en.wikipedia.org/wiki/PSTAR&quot; rel=&quot;nofollow&quot;&gt;PSTAR&lt;/a&gt;, and will be doing my ROC-A in the upcoming weeks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With this in mind, must I do the entire online ground school course? I do not know if my instructor (or worse, the FAA) will check if I have finished all of the online work.&lt;/p&gt;&#xA;" OwnerUserId="9449" LastEditorUserId="65" LastEditDate="2015-07-21T14:34:59.840" LastActivityDate="2015-07-21T14:34:59.840" Title="If I do PPL ground school online, do I have to do all of it?" Tags="&lt;flight-training&gt;&lt;ppl&gt;&lt;transport-canada&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17064" PostTypeId="2" ParentId="16935" CreationDate="2015-07-21T00:00:23.300" Score="3" Body="&lt;p&gt;A large part of the noise produced by rotor wing aircraft comes from the drive system. The engines themselves make quite a bit of noise and it is technically infeasible to make them quieter.&lt;/p&gt;&#xA;" OwnerUserId="9440" LastActivityDate="2015-07-21T00:00:23.300" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17065" PostTypeId="1" CreationDate="2015-07-21T00:41:22.287" Score="5" ViewCount="3713" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.56&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.56 (c)&lt;/a&gt; requires pilots to perform a &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.56&quot; rel=&quot;nofollow&quot;&gt;Flight Review&lt;/a&gt; every 24 calendar months unless another applicable action has been taken in order to be eligible to act as pilot in command of an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.56&quot; rel=&quot;nofollow&quot;&gt;requirements of a flight review&lt;/a&gt; state that a minimum of 1 hour of flight instruction and 1 hour of ground instruction are required to complete that review.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question concerns the logging of that activity. In the past my instructors have given me an signed logbook entry for the flight time, a description of the training received and materials reviewed a logbook endorsement stating that the flight review was performed. Most logbooks have a section for ground instruction, but I've never logged specific ground time there during a flight review. For a flight review to be valid does the ground instruction actually need to be logged separately from the flight instruction? Or is the ground instruction implied by the endorsement?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-07-22T01:46:48.490" LastActivityDate="2015-07-22T01:46:48.490" Title="How should a flight review be logged?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17066" PostTypeId="2" ParentId="17052" CreationDate="2015-07-21T00:45:32.473" Score="15" Body="&lt;p&gt;The short answer is that you'd need a commercial certificate, and potentially a commercial operator's license, to do what you're describing. &lt;strong&gt;Standard disclaimer&lt;/strong&gt;: IANAL, and if you wanted to do anything like this, you really should &lt;strong&gt;find an aviation lawyer&lt;/strong&gt; and get answers from them in writing!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rules that cover this are contained in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.1.2.5.1.8&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;FAR 61.113&lt;/a&gt;, quoted in relevant part:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§61.113   Private pilot privileges and limitations: Pilot in command.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Except as provided in paragraphs (b) through (h) of this section, no person who holds a private pilot certificate may act as pilot in command of an aircraft that is carrying passengers or property for compensation or hire; nor may that person, for compensation or hire, act as pilot in command of an aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) A private pilot may, for compensation or hire, act as pilot in command of an aircraft in connection with any business or employment if:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) The flight is only incidental to that business or employment; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) The aircraft does not carry passengers or property for compensation or hire.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;(c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To point 1, the answer is no. You're being compensated for your time, which is spent flying. If you were alone, 61.113(b) would allow you to be compensated - but that only applies if the aircraft does not carry passengers. Since the 61.113(b) exclusion doesn't apply, you're stuck with 61.113(a)'s prohibition of flying for compensation or hire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You make an interesting point at the beginning about salary covering strange hours. If you really were paid just for your productivity, and you had an arrangement where you could just go take a couple of hours off in the middle of the day to go flying (or any other personal activity) without burning leave or affecting your pay, you could claim that you weren't being compensated for your time. I might write to the local FSDO for clarity on that before actually doing it, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were an hourly worker (#3) and were not paid for the time you were flying, that would eliminate some of the compensation. Note, however, that the FAA constructs &quot;compensation&quot; very broadly, to include good-will from others. If you made this flight in order to make your boss happy, you're being compensated! The source of the incentive to fly would be important: if you and a co-worker had to get to a destination, and you suggested, &quot;Let's fly there!&quot;, you're under much better grounds than if your boss told you to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second point would depend on your normal work situation. Let's look at two portions of the flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The portion from home to work, and from work back home: In this case, you could be compensated for the flight under 61.113(b) - both in salary and costs, as long as your employer has a policy of reimbursing staff for their commuting costs.&lt;/li&gt;&#xA;&lt;li&gt;The &quot;non-commuter&quot; costs: You could ask for 50% of the costs of the flight under 61.113(c) (see Mangiamele interpretation) - but from your co-worker, not your employer. Where they get that money is up to them. One important point: 61.113(c) requires &quot;bona fide common purpose&quot; -- you and your co-worker must each have a reason, beyond the flight itself, for going to the destination airport. If you weren't required to meet the client (or do something else that requires you to physically be in Waco at that time), you could not even share the costs of flight. Note that you can't be paid or reimbursed for your 50% — you have to eat that cost yourself.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To #4, the owner of the plane doesn't matter that much here, for a private pilot. The question of who provides the plane becomes very important in common carriage, but that's a different question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To your last point, I'm not a lawyer - but I imagine that being fired for refusing to take an illegal action would be wrongful termination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further Reading:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/news/safety_briefing/2010/media/SepOct2010-ComeFlyWithMe.pdf&quot; rel=&quot;noreferrer&quot;&gt;An FAA Article on cost sharing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/mangiamele%20-%20%282009%29%20legal%20interpretation.pdf&quot; rel=&quot;noreferrer&quot;&gt;Mangiamele Interpretation&lt;/a&gt;: a letter from the FAA Office of Legal Counsel discussing this topic&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2016-01-09T22:20:25.527" LastActivityDate="2016-01-09T22:20:25.527" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17067" PostTypeId="2" ParentId="17065" CreationDate="2015-07-21T01:50:56.633" Score="1" Body="&lt;p&gt;Just use the ground s hook column, and add it to the notes, like you do with student pilots.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-21T01:50:56.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17068" PostTypeId="2" ParentId="17047" CreationDate="2015-07-21T02:02:12.427" Score="4" Body="&lt;p&gt;For tailwheel aircraft, I chock the main on the side with the door (usually right), and the tail to keep it from pivoting. If there's a tail tie down,  I will always tie down the tailwheel, and I will attempt to park into the wind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As my instructor used to say &quot;the flight's not over till the tailwheel is tied down&quot;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-07-21T14:30:04.073" LastActivityDate="2015-07-21T14:30:04.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17069" PostTypeId="1" AcceptedAnswerId="17072" CreationDate="2015-07-21T02:13:50.837" Score="12" ViewCount="6538" Body="&lt;p&gt;Let's take a classic example. An instrument rated pilot is flying a C-172 and wants to maintain instrument currency. The pilot goes flying and performs some approaches, holding and intercept/tracking to maintain that currency, all while under the hood. In order to maintain a safe condition, a safety pilot is brought along to maintain VFR conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, how should the safety pilot log this time? In this condition the safety pilot is a required crew member, but is this time technically SIC or is it PIC?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="62" LastEditDate="2018-10-07T23:25:42.417" LastActivityDate="2018-10-07T23:25:42.417" Title="How should time as safety pilot be logged?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17070" PostTypeId="2" ParentId="17032" CreationDate="2015-07-21T02:15:30.300" Score="2" Body="&lt;p&gt;Power pilots (which I am also) are the wrong pilots to ask about this topic. We are trained to stay away from this kind of topography for all the reasons listed&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glider pilots fly ridges and mountain wave all the time, very close to the ridge line. Ridges and mountains provide all sorts of lift, which is the key to great soaring, and we are taught to fly IN it, not away from it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My recommendation is to read the first part of Helmut Reichmann's &lt;em&gt;Cross-country Soaring&lt;/em&gt; called &quot;Flight in Lift&quot; which details the answers to the questions you're asking. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as helis are concerned, which I also fly, the the big considerations for mountain flying is how much excess power you have. When you encounter a downdraft in a heli, you  have to add power to arrest a decent, so it's important to know your power, weight, and density altitude limits. There are a few helis that are known as good mountain machines, like the AS350. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any aircraft, if you're going to fly in the mountains, you have to be able to read the signs: surface winds and winds aloft, cloud patterns, areas of airmass convergence, etc &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-07-21T02:29:43.967" LastActivityDate="2015-07-21T02:29:43.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17071" PostTypeId="1" AcceptedAnswerId="17073" CreationDate="2015-07-21T03:39:17.843" Score="13" ViewCount="38724" Body="&lt;p&gt;I read an article that mentioned &quot;V&lt;sub&gt;MO&lt;/sub&gt;&quot; speeds of a 747 and that the plane, when it exceeds its V&lt;sub&gt;MO&lt;/sub&gt;, shakes uncontrollably and destroys itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never heard of planes doing this and the article explained V&lt;sub&gt;MO&lt;/sub&gt; in a way that is beyond my understanding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For someone that doesn't know much about aviation: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does V&lt;sub&gt;MO&lt;/sub&gt; stand for and how does it affect planes when exceeded? If it does cause the plane to shake to the point that it destroys itself, why is that?&lt;/p&gt;&#xA;" OwnerUserId="9303" LastEditorUserId="3386" LastEditDate="2015-07-23T13:17:01.593" LastActivityDate="2018-12-18T20:09:30.787" Title="What exactly is VMO and how does it affect a plane when it is exceeded?" Tags="&lt;v-speeds&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17072" PostTypeId="2" ParentId="17069" CreationDate="2015-07-21T06:06:53.053" Score="11" Body="&lt;p&gt;The rules for safety pilots are spelled out in 91.109c but don't specifically state how the safety pilot should log the hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the common consensus I've heard from friends is that you can indeed log safety pilot time as PIC time. The &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2015/August/feature-buddy.html&quot; rel=&quot;noreferrer&quot;&gt;August 2015&lt;/a&gt; Flight Training magazine had an article about this actually. Here is what they said:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is implied but not specifically stated in the regulation is important. Because safety pilots are responsible for determining the safety of the flight, they can log their right-seat time when the left seat pilot is wearing a view-limiting device as PIC time. This transforms time spent serving as a safety pilot into a truly valuable educational experience that will also expand the flight time totals in your logbook&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Edit: I did some more research into this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PIC time is defined in Part &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/0367625A797466AA8625793B0068F34D?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;61.51(e)&lt;/a&gt;. Safety pilots can qualify as PIC under bullet iii:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) When the pilot, except for a holder of a sport or recreational pilot certificate, acts as pilot in command of an aircraft for which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are some other things to be aware of when logging PIC time as a safety pilot (in addition to the requirements of 91.109c):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The two pilots must agree that the safety pilot is the acting&#xA;PIC. &lt;/li&gt;&#xA;&lt;li&gt;PIC time may be logged only while the other pilot is&#xA;&quot;under-the-hood.&quot;&lt;/li&gt;&#xA;&lt;li&gt;If something goes wrong you are the one that will be held responsible. I wouldnt take the responsibility lightly. &lt;/li&gt;&#xA;&lt;li&gt;The pilot logging instrument time must record the safety pilots name in their logbook under 61.51(g)(3)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7269" LastEditorUserId="7269" LastEditDate="2015-07-21T19:46:04.573" LastActivityDate="2015-07-21T19:46:04.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17073" PostTypeId="2" ParentId="17071" CreationDate="2015-07-21T06:57:38.377" Score="18" Body="&lt;p&gt;$V_{MO}$ is a “maximum operating speed”. It is one of many “&lt;a href=&quot;https://en.wikipedia.org/wiki/V_speeds&quot; rel=&quot;noreferrer&quot;&gt;V-speeds&lt;/a&gt;” defined for an aircraft that limit operation at various flight phases. All V-speeds are &lt;a href=&quot;https://en.wikipedia.org/wiki/Indicated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;indicated airspeeds&lt;/a&gt;¹.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The $V_{MO}$ is the maximum permitted speed for the aircraft. This includes a safety margin, so pilots can reasonably fly near that speed. Exceeding it is not immediately dangerous, but as it reduces safety margins, is an incident that should be investigated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another speed, $V_{NE}$, the “never exceed speed”, which is somewhat higher and which marks the point where things start to get dangerous. When the aircraft exceeds $V_{NE}$, &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroelasticity#Flutter&quot; rel=&quot;noreferrer&quot;&gt;aeroelastic flutter&lt;/a&gt; may develop that will destroy the aircraft and/or important parts may break off as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamic_pressure&quot; rel=&quot;noreferrer&quot;&gt;dynamic pressure&lt;/a&gt; becomes higher than what they are designed for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also these speeds have their &lt;a href=&quot;https://en.wikipedia.org/wiki/Mach_number&quot; rel=&quot;noreferrer&quot;&gt;Mach number&lt;/a&gt; counterparts², $M_{MO}$ and $M_{NE}$. At high altitude, the same indicated airspeed (IAS) corresponds to much higher true air-speed, since indicated airspeed decreases with pressure, while the same Mach number corresponds to slightly lower true air-speed, since speed of sound only depends on temperature. So at high altitudes, the Mach limits are reached first while at low altitudes the IAS limits are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exceeding the $M_{NE}$ has different effect, though also dangerous. Above that speed flow separation occurs above the wing due to supersonic speed of the flow. This leads to loss of lift and significant down-pitching moment (a.k.a &lt;a href=&quot;https://en.wikipedia.org/wiki/Mach_tuck&quot; rel=&quot;noreferrer&quot;&gt;mach tuck&lt;/a&gt;), which aircraft not designed for supersonic flight may not have enough elevator authority to compensate.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ The airspeeds are given as &lt;a href=&quot;https://en.wikipedia.org/wiki/Indicated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;IAS&lt;/a&gt;, the speed measured by pitot probes, so they can be directly compared to the indication in cockpit (aircraft with &lt;a href=&quot;https://en.wikipedia.org/wiki/Electronic_flight_instrument_system&quot; rel=&quot;noreferrer&quot;&gt;EFIS&lt;/a&gt; (“glass cockpit”) usually correct those measurement errors that can be estimated, showing so called &lt;a href=&quot;https://en.wikipedia.org/wiki/Calibrated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;calibrated airspeed (CAS)&lt;/a&gt;). However it may not be just a simple number but may be tabulated depending on other parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular $V_{NE}$ and $V_{MO}$ may depend on altitude, because &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroelasticity#Flutter&quot; rel=&quot;noreferrer&quot;&gt;flutter&lt;/a&gt; depends on &lt;a href=&quot;https://en.wikipedia.org/wiki/True_airspeed&quot; rel=&quot;noreferrer&quot;&gt;true airspeed (TAS)&lt;/a&gt; and at lower density (due to lower pressure at altitude) the same TAS corresponds to lower &lt;a href=&quot;https://en.wikipedia.org/wiki/Equivalent_airspeed&quot; rel=&quot;noreferrer&quot;&gt;EAS&lt;/a&gt;/&lt;a href=&quot;https://en.wikipedia.org/wiki/Calibrated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;CAS&lt;/a&gt;/&lt;a href=&quot;https://en.wikipedia.org/wiki/Indicated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;IAS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² Mach number is true airspeed as fraction of speed of sound. In this case the limiting factor is formation of shockwaves due to the flow speed locally exceeding speed of sound around some parts of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-07-21T19:34:35.970" LastActivityDate="2015-07-21T19:34:35.970" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="17074" PostTypeId="1" AcceptedAnswerId="17076" CreationDate="2015-07-21T07:52:45.170" Score="14" ViewCount="1650" Body="&lt;p&gt;We &lt;a href=&quot;http://www.bbc.com/news/world-europe-33564237&quot; rel=&quot;nofollow&quot;&gt;recently had some forest fires in Athens&lt;/a&gt;, Greece while the weather was very windy. The news said it had &lt;a href=&quot;https://en.wikipedia.org/wiki/Beaufort_scale#Modern_scale&quot; rel=&quot;nofollow&quot;&gt;8 beaufort&lt;/a&gt; of wind speed (34-40 knots, 38–46 mph) and in these conditions it's dangerous to fly the &quot;canadairs&quot; (I think we have Canadair CL-215 and Bombardier 415).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true? What is a wind speed over which one wouldn't want to fly such a plane?&lt;/p&gt;&#xA;" OwnerUserId="9454" LastEditorUserId="9454" LastEditDate="2015-07-22T01:26:45.473" LastActivityDate="2015-07-22T01:26:45.473" Title="Wind speed over which a Canadair fire fighting plane cannot safely fly?" Tags="&lt;wind&gt;&lt;fire&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17075" PostTypeId="2" ParentId="17061" CreationDate="2015-07-21T08:15:00.817" Score="7" Body="&lt;p&gt;Aircraft are designed with ditching in mind, but the outcome depends on many circumstances, most importantly on how calm the water is and how well the aircraft can be controlled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Water_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ditching&lt;/a&gt; lists emergency water landings and other accidents where aircraft ended in water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no ditching by 747, so we don't have any specific reference. However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;B747 is not that different from other types of aircraft. Controlled ditchings on calm water were successful in different types; it is likely that one would be possible with B747 too.&lt;/li&gt;&#xA;&lt;li&gt;How long the aircraft would remain afloat depends on the damage. But if it did not break up, it would likely manage to keep afloat for the 90 seconds needed for evacuation. And the slides can be used as life rafts.&lt;/li&gt;&#xA;&lt;li&gt;There was one case where B747 ended up in water after overrunning runway (so at lower speed than landing), &lt;a href=&quot;https://en.wikipedia.org/wiki/China_Airlines_Flight_605&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines flight 605&lt;/a&gt;, and the aircraft did remain afloat long enough to evacuate it.&lt;/li&gt;&#xA;&lt;li&gt;Also any aircraft that will be used for flying across large bodies of water, which obviously includes all variants of B747, must be &lt;a href=&quot;https://aviation.stackexchange.com/questions/819/why-would-an-airplane-be-approved-for-ditching&quot;&gt;certified for ditching&lt;/a&gt;. This involves designing it so that, at least according to model, a controlled ditching will be smooth enough not to cause serious injuries to occupants and will leave it afloat long enough for successful evacuation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-21T14:12:09.697" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17076" PostTypeId="2" ParentId="17074" CreationDate="2015-07-21T08:25:23.993" Score="17" Body="&lt;p&gt;The problem is not the wind speed per se, but the combination of factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's start from the data; this is the METAR for Athens on the 17th of July, the day of the fires:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;METAR LGAV 171220Z 030&lt;strong&gt;26G38KT&lt;/strong&gt; CAVOK 32/10 Q1016 NOSIG=&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have highlighted the wind speed data. It says that the wind at Athens airport was on average at 26 kts, with gusts up to 38 kts&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;26 kts of wind at high altitude would not be a problem for a CL-215&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;26 kts of wind near ground (to drop the water it has to do low passes) and at low speed (it has to go as slow as possible to be precise) can be highly dangerous, as proximity with the ground increases turbulence. Let's also consider the mountainous terrain around Athen (and the fires were on the side of a mountain), windshear and turbulence were probably quite strong. (See also this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/17032/turbulence-crossing-a-ridge-at-low-height-above-terrain&quot;&gt;When crossing a mountain ridge at low height above terrain what consideration is given to turbulence?&lt;/a&gt; )&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;26 kts was the average wind speed, gusts were up to 38 kts, increasing the risks of such operations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In addition to the above, let's remember that these aircrafts have to fly over fires, that will create additional turbulence through the rising hot air column that they generate. (thanks to &lt;a href=&quot;https://aviation.stackexchange.com/users/946&quot;&gt;David Richerby&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not think that a hard limit for such operation exists, as said above is the combination of windspeed, terrain configuration and mission that determines if an aircraft can perform it or not.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-07-21T19:22:49.893" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="17077" PostTypeId="1" AcceptedAnswerId="17104" CreationDate="2015-07-21T10:43:10.430" Score="10" ViewCount="31981" Body="&lt;p&gt;I'm studying the &lt;a href=&quot;https://en.wikipedia.org/wiki/Integrated_modular_avionics&quot; rel=&quot;nofollow noreferrer&quot;&gt;Integrated Modular Avionics&lt;/a&gt; (IMA) and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Line-replaceable_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;Line-Replaceable Unit&lt;/a&gt; (LRU), but I don't get the difference. &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="1696" LastEditDate="2018-06-10T19:03:28.037" LastActivityDate="2020-10-17T20:39:31.903" Title="What is the difference between Line-Replaceable Unit (LRU) and Integrated Modular Avionics (IMA)?" Tags="&lt;avionics&gt;&lt;ima&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17079" PostTypeId="2" ParentId="16971" CreationDate="2015-07-21T11:18:12.200" Score="1" Body="&lt;p&gt;From &lt;a href=&quot;http://av-info.faa.gov/dd_sublevel.asp?Folder=%5CAirOperators&quot; rel=&quot;nofollow&quot;&gt;FAA website&lt;/a&gt;, there is a list of Air Operator to download. You can choose the format you like and open it in your favourite spreadsheet. How to delimit the file depends on your program and out of scope here.&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-07-21T11:18:12.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17080" PostTypeId="2" ParentId="17063" CreationDate="2015-07-21T12:26:05.183" Score="3" Body="&lt;p&gt;You need at least 40 hours of ground school, according to the &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/regserv/cars/part4-standards-421-1086.htm#421_26&quot; rel=&quot;nofollow noreferrer&quot;&gt;Transport Canada regulations (421.26)&lt;/a&gt;. So you will need some sort of evidence to show that you have done so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do hope that you weren't seriously considering doing this. Please read the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/198/how-dangerous-is-flying-in-a-single-engine-plane&quot;&gt;this question&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will see a common theme - most accidents are caused by the pilots themselves. Knowing aviation theory inside and out is the best protection you have against joining them in those statistics. It is not a stretch to say that your life depends on the attitude you bring to your flight - starting from the first lesson of ground school. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-21T12:26:05.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17081" PostTypeId="2" ParentId="17077" CreationDate="2015-07-21T12:29:08.143" Score="5" Body="&lt;p&gt;An IMA is a computer network utilising the ARINC bus system that interconnects various devices. This is in contrast to Line Replaceable Units LRU'S where they are standalone systems that can be replaced. Basically they are electronic boxes typically in the aircrafts electronics bay that can be swapped out quickly. Because they can be swapped out quickly they can be done on the line. Ie. When the airplane is on the tarmac or in the hangar  &lt;/p&gt;&#xA;" OwnerUserId="8774" LastEditorUserId="1467" LastEditDate="2015-07-23T16:45:43.367" LastActivityDate="2015-07-23T16:45:43.367" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17082" PostTypeId="1" AcceptedAnswerId="17087" CreationDate="2015-07-21T12:56:59.457" Score="24" ViewCount="9981" Body="&lt;p&gt;This question came across my mind when I was thinking about cockpit design vs car design: why don't we have yokes that look like steering wheels?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first advantage I can think of is more gestures to hold the yoke. You can hold a steering wheel in many ways, e.g. 2 &amp;amp; 10 o'clock, 3 &amp;amp; 9 o'clock, top, bottom, one hand, both hands etc. And one can still pull or push the yoke even if it's circular.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, in most (if not all) of the yokes, full aileron deflection is achieved when the yoke is rotated approximately 90 degrees. Would it be beneficial if it's 180 degree instead, allowing more fine control?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-07-22T13:42:18.220" Title="Why don't we have yokes that look like steering wheels?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17083" PostTypeId="1" CreationDate="2015-07-21T13:06:25.020" Score="5" ViewCount="3222" Body="&lt;p&gt;I have heard some &lt;em&gt;slang&lt;/em&gt; terms used mainly by ATCs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;follow the black holes&lt;/li&gt;&#xA;&lt;li&gt;taxi not too deep&lt;/li&gt;&#xA;&lt;li&gt;how is your ride&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What do they actually mean and are there others?&lt;/p&gt;&#xA;" OwnerUserId="9458" LastEditorUserId="19" LastEditDate="2016-07-08T11:50:36.880" LastActivityDate="2016-07-08T11:50:36.880" Title="What is the meaning of these slang terms used in ATC?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17084" PostTypeId="2" ParentId="17082" CreationDate="2015-07-21T13:15:10.947" Score="20" Body="&lt;p&gt;With a steering wheel in a car, the driver can judge how far it is rotated without looking at it by at least three means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a car, the driver:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;can extrapolate visually the curved path he or she is moving along.&lt;/li&gt;&#xA;&lt;li&gt;usually experiences centripetal force on his or her body.&lt;/li&gt;&#xA;&lt;li&gt;feels the feedback of the steering assembly. Whether purely mechanical or assisted, steering assemblies are self-centering. If the driver releases the wheel, it will return to neutral.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In a plane, the pilot:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;may be relying on instruments and have no outside cues.&lt;/li&gt;&#xA;&lt;li&gt;may have a false seat-of-the-pants sense of attitude and direction.&lt;/li&gt;&#xA;&lt;li&gt;should not need to make violent or large steering movements.&lt;/li&gt;&#xA;&lt;li&gt;has no need to 'steer' around a corner as you do in a car. Once a new attitude is attained, it should remain stable until the pilot corrects it back to normal (this is a rather simplified statement).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The yoke's shape is valuable because it easily informs the pilot of the yoke's rotation with high precision.&lt;/p&gt;&#xA;" OwnerUserId="9417" LastEditorUserId="9417" LastEditDate="2015-07-22T00:03:49.920" LastActivityDate="2015-07-22T00:03:49.920" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17085" PostTypeId="2" ParentId="17082" CreationDate="2015-07-21T13:15:58.123" Score="31" Body="&lt;p&gt;We Do! It just has been a while since anyone has built a plane like that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many early planes did, notably the curtis biplane comes to mind&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/77tvT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As closed cockpits came into be and the modern control set up we see something like a car wheel.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The cockpit of the Reliant SR-6A shows the love and skill that went into the restoration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KlShD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&#xA;&lt;a href=&quot;http://www.airventure.de/oshkosh05engl_01.htm&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yokes then evolved to have a more cut down top like the one seen here (in my favorite plane) the &lt;a href=&quot;https://en.wikipedia.org/wiki/Spartan_Executive&quot;&gt;Spartan Execuitve&lt;/a&gt; This plane was built in the 30's &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/faEnX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even later than that the &lt;a href=&quot;https://en.wikipedia.org/wiki/ERCO_Ercoupe&quot;&gt;Ercoupe&lt;/a&gt; has a somewhat rounded control wheel. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/i0GBe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also of note the &lt;a href=&quot;https://www.google.com/webhp?sourceid=chrome-instant&amp;amp;ion=1&amp;amp;espv=2&amp;amp;ie=UTF-8#q=PA-20%20cockpit&quot;&gt;Piper Pacer&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_140&quot;&gt;Cessna 140&lt;/a&gt; had rounded yokes. After that period most of the big makers moved to the yoke we know and love today. Piper would have a closed top yoke on their early &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-24_Comanche&quot;&gt;Comanches&lt;/a&gt; through the early 60's as well. It should also be noted that early planes (wright flyer etc) had stick like controls. I would assume this was to allow the cable to be mounted far from the pivot for torque reasons although Im not sure (this was for sure before trim). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember in an airplane its all about weight so trimming it where ever you can is worth it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a plane the maximum deflection of a yoke is often no more than 90 degrees so having a full wheel (which allows a hand over hand car style turn) is not necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orientation is a bit of a concern when flying on instruments but many race cars have center marks on their steering wheels for a similar reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth formula 1 steering wheels see about as much travel as a yoke and are similarly shaped. Some even have more buttons than a cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nhpYE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.nbcnews.com/id/42328416/ns/technology_and_science-tech_and_gadgets/t/k-race-car-steering-wheel-even-pours-drinks/&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-21T14:32:49.723" LastActivityDate="2015-07-21T14:32:49.723" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17086" PostTypeId="2" ParentId="17082" CreationDate="2015-07-21T13:37:18.130" Score="13" Body="&lt;p&gt;Steering wheels were developed for cars to provide the large amount of leverage necessary to turn the wheels of a car without any power assist. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In planes, you don't need that much leverage (ok maybe in some long-wing aircraft) to control the elevator and ailerons, and the stick is mostly centered, even in turns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idiom for fine control of the yoke is to &quot;milk the mouse&quot;, and use two, maybe, three fingers so as not to overcontrol. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-21T13:37:18.130" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17087" PostTypeId="2" ParentId="17082" CreationDate="2015-07-21T15:46:30.347" Score="19" Body="&lt;p&gt;Short answer: &lt;strong&gt;Because you only use one hand on the yoke.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: In an airplane, you almost always fly with only one hand on the yoke (or none, as the case may be.) You will be using your other hand for power adjustments, setting flaps, adjusting radios, setting instruments, writing, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a car, power is adjusted with your feet, so you don't need your second hand for power adjustments and there aren't really any other particularly critical controls that need to be manipulated frequently or precisely. However, in an airplane, you have to be able to precisely control &lt;strong&gt;three&lt;/strong&gt; axes of rotation, not just one like in a car. As such, your feet are needed for yaw control (and differential braking,) which means power must instead be controlled by hand. So, there's no need for the various grip positions that you could use with a wheel because you don't want your second hand on the yoke in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, having a 90-degree angle (or nearly so, as the case may be) allows for a better grip than the smooth curve of a steering wheel. You can place 2 or 3 fingers above the horizontal bar and the others below, which prevents your hand from slipping up or down the control wheel, as is possible with a normal car steering wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the second question of whether it would be better to have 180 degrees equal full deflection, that would mean you would either need 2 hands on the yoke in order to command full deflection, which is not good for the reasons already mentioned, or have a weaker grip on the yoke that would allow you to rotate it 180 degrees either direction. If you have a firm grip on the yoke, your wrist will simply not be able to rotate enough to turn it upside down without releasing your grip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also important to note the difference here between what the yoke controls versus what a car steering wheel controls. A car steering wheel directly controls your turn rate. Thus, a car whose steering wheel is in the neutral position will not be turning. In an airplane, however, your current bank angle controls your turn rate. An aileron deflection changes your bank angle. Having the ailerons in the neutral position will not cause you to fly straight forwards, but rather will simply leave your bank angle (and thus your turn rate) at its present value (&lt;a href=&quot;https://aviation.stackexchange.com/q/17019/755&quot;&gt;if we ignore the effects of dihedral and such&lt;/a&gt;.) Thus, you don't need as much possible input control range to get precise turn rate control.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-21T15:46:30.347" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="17088" PostTypeId="1" CreationDate="2015-07-21T16:35:25.747" Score="2" ViewCount="1048" Body="&lt;p&gt;A coaxial rotor helicopter is connected to the same engine and has the advantage of anti-torque and a +/- 25% increase in lift.&#xA;My question is if a coaxial ducted fan connected to the same engine would also have a +/- 25% increase in forward motion ?&lt;/p&gt;&#xA;" OwnerUserId="8664" LastEditorUserId="3386" LastEditDate="2017-05-08T08:48:52.733" LastActivityDate="2017-05-08T08:48:52.733" Title="Are the advantages of a coaxial rotor on a helicopter also applicable to a ducted fan?" Tags="&lt;aircraft-performance&gt;&lt;engine&gt;&lt;rotorcraft&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17089" PostTypeId="2" ParentId="17065" CreationDate="2015-07-21T17:04:38.693" Score="6" Body="&lt;p&gt;Short answer: log it however you like as long as you log it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2061-98B.pdf&quot; rel=&quot;noreferrer&quot;&gt;According to the FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the applicant has successfully  completed the review, the CFI&#xA;  should endorse the pilot’s logbook to certify that the pilot has &#xA;  satisfactorily accomplished the flight review.  The CFI should make&#xA;  the endorsement for a  satisfactory review in accordance with AC 61-&#xA;  65. The flight and ground time must also be  logged in the pilot’s logbook in  accordance with § 61.51(a)(1)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;noreferrer&quot;&gt;61.51(a)(1)&lt;/a&gt; simply says that &quot;Training and aeronautical experience used to meet the requirements for a certificate, rating, or flight review of this part&quot; must be logged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you do have to log both ground and flight time, but exactly &lt;em&gt;how&lt;/em&gt; you do that is really up to you. The FAA doesn't require any specific logging format as long as the information is correct and CFIs, DPEs and others can see what they need to see.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I would note the ground time beside the CFI's endorsement and then log the flight time as I would for any other training flight. I've never met anyone who logged their 'ground instruction' time precisely (simulator time is a different story), but if you want to then you can do it any way that works for you. The FAA just wants you to log &lt;em&gt;something&lt;/em&gt; that shows you did receive the necessary ground training.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-21T17:04:38.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17090" PostTypeId="2" ParentId="3804" CreationDate="2015-07-21T18:27:53.320" Score="0" Body="&lt;p&gt;Overshoot could be, also, when the pilot is not able to intercept the localizer, due to a sharp bank, or faster than usual, missing to intercept it. e.g.: The crew overshot the localizer, then they decided to start a new approach procedure.&lt;/p&gt;&#xA;" OwnerUserId="9458" LastActivityDate="2015-07-21T18:27:53.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17091" PostTypeId="1" AcceptedAnswerId="17095" CreationDate="2015-07-21T18:45:28.527" Score="6" ViewCount="903" Body="&lt;p&gt;Are there rules that require one of the pilots in a large commercial aircraft to have positive physical control of the yoke/joystick at all times?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the same question for the rudder actuators, if any (pedals)?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2017-01-25T12:38:09.977" LastActivityDate="2017-01-25T12:38:09.977" Title="Are there any rules requiring hands/feet on the controls at all times?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;flight-controls&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17092" PostTypeId="2" ParentId="2928" CreationDate="2015-07-21T19:09:31.717" Score="2" Body="&lt;p&gt;The aircraft is a modified Douglas A-26 Invader. As mentioned in an earlier reply there were several companies which undertook such work. Most well known was On-Mark Engineering of Van Nuys, CA. The 26 in question, N36B was one of several (at least two used the same reg.) owned by citrus tycoon Willis (Bill) Bailard of Santa Barbara, CA. He had at least three of them over the years. Possibly four. Including an unpressurized On-Mark Marketeer.&#xA;This example does not have the ring- spar mod as later versions did, and I suspect that it is an earlier Grand Central exec. version. Note also in the movie that the 26 still has the fittings for the upper turret installed.&lt;/p&gt;&#xA;" OwnerUserId="9464" LastActivityDate="2015-07-21T19:09:31.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17093" PostTypeId="2" ParentId="17091" CreationDate="2015-07-21T19:23:27.730" Score="-7" Body="&lt;p&gt;Nope. Sometimes they just let go and yell, &quot;Look Ma! No hands!&quot; into the local traffic channel. Just kidding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be a slight disconnect here in how you think about pilots and the law. The average (non-pilot) person imagines that pilots are robotic servants that must obey all kinds of laws and regulations designed to &quot;protect&quot; passengers and slavishly follow orders from (non-pilot) FAA controllers. That is not how it works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the sky, the pilots are the bosses. ATC and the laws are there to help the pilots do their job better, not boss them around and force them to them to do things they don't want to do.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-21T19:23:27.730" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17094" PostTypeId="1" CreationDate="2015-07-21T19:43:13.927" Score="13" ViewCount="1916" Body="&lt;p&gt;Why is it carburetor icing has to be handled manually by the pilot, at least in a helicopter? I am hoping very soon to take my PL/H lessons, I have a little understanding of mechanics and how things work and this is one subject that puts the willies up me as a potential student helicopter pilot. Why can it not be an automatic response built into the engine? After all, this is the 21st century.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I am assuming every motorized engine is the same, so why does a helicopter require a manual response to carb icing but a motor vehicle doesn't? Do we not notice it because the vehicle is on the ground?&lt;/p&gt;&#xA;" OwnerUserId="9466" LastEditorUserId="62" LastEditDate="2015-07-21T21:23:59.497" LastActivityDate="2016-02-15T12:40:26.310" Title="Why does carburetor icing require manual attention by the pilot?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;piston-engine&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17095" PostTypeId="2" ParentId="17091" CreationDate="2015-07-21T19:48:15.507" Score="10" Body="&lt;p&gt;There is nothing I can find in the FARs requiring that a pilot keep their hands and feet on the controls at all times.&lt;br&gt;&#xA;Such a requirement would be impractical and dangerous in many situations (such as when writing down a clearance in the air: For most people if you keep your hands on the controls while writing you will have a tendency to push, pull, or twist them, resulting in unintended attitude changes). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The most relevant sections of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&quot;&gt;Part 91&lt;/a&gt; would be 91.3 and 91.13:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR 91.3 (FAR 91.3) says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.3   Responsibility and authority of the pilot in command.&lt;/strong&gt;&lt;br&gt;&#xA;  (a) The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.&lt;br&gt;&#xA;  . . . . &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and 14 CFR 91.13 (FAR 91.13) says:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.13   Careless or reckless operation.&lt;/strong&gt;&lt;br&gt;&#xA;  (a) &lt;em&gt;Aircraft operations for the purpose of air navigation.&lt;/em&gt;&lt;br&gt;&#xA;   No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) &lt;em&gt;Aircraft operations other than for the purpose of air navigation.&lt;/em&gt;&lt;br&gt;&#xA;  No person may operate an aircraft, other than for the purpose of air navigation, on any part of the surface of an airport used by aircraft for air commerce (including areas used by those aircraft for receiving or discharging persons or cargo), in a careless or reckless manner so as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically it's perfectly legal for a pilot to fly with their arms crossed and their feet flat on the floor, even without an autopilot, as long as the pilot in command remains able to exercise operational control of the aircraft as required to ensure the flight remains safe and legal, and as long as they are not acting in a &quot;careless or reckless manner&quot; (like letting their altitude wander all over the place while sitting with their arms crossed).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-21T19:48:15.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17097" PostTypeId="2" ParentId="17091" CreationDate="2015-07-21T19:53:00.143" Score="6" Body="&lt;p&gt;No. What is required by FAA is that one of the two pilots (the captain or first officer) must be the &quot;pilot flying&quot;, and this pilot has primary responsibility for maintaining control of the aircraft at the time. The other pilot, the &quot;pilot not flying&quot;, may assist the pilot flying by performing secondary tasks such as communication or navigation, or he/she may use the lav, have a snack/drink, read (the FAA does not prohibit reading materials not directly related to the job, but some companies do), do puzzles (ditto), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither of these pilots are required to have hands on stick/yoke/throttle and feet on rudder pedals at all times. First off, it's redundant for most of the flight; when cruising, the plane is on autopilot, which will keep the wings level and the plane on a designated course. Second, airliners (in fact, most civilian fixed-wing aircraft) are much more stable in flight than helicopters, which &lt;em&gt;do&lt;/em&gt; require someone to have their hands on the cyclic stick at all times to keep the helicopter &quot;on top of&quot; the lift vector of its rotors. So, even if the autopilot is disengaged, in normal, calm conditions the plane will almost fly itself, requiring only small corrections for turbulence. In any case, a &quot;ham-fist&quot; or &quot;lead foot&quot; on the controls is a common student mistake, much like in driving; pilots usually try to heed Han Solo's advice: &quot;fly casual&quot;.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-22T21:56:04.393" LastActivityDate="2015-07-22T21:56:04.393" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17098" PostTypeId="2" ParentId="17061" CreationDate="2015-07-21T19:55:17.740" Score="-2" Body="&lt;p&gt;Concerning floating: planes tend to float for a long time, potentially indefinitely. The reason for this is that they are much lighter than water. For example, jet fuel is about 80% of the density of fresh water, so even if the wings were fully loaded with fuel, they would be lighter than water. Some of the space in the wing tanks is air, which of course is even lighter. There are vents in the tanks, but it would tank a long time like many hours or probably days before a wing could even partially fill up with water. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning survivability: there is no way to predict the outcome. It would depend completely on the reactions and skill of the pilot and exactly when the engines lost power. In general, landing on water is not a problem, as was seen in the accident of &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow&quot;&gt;US Air 1549&lt;/a&gt;. A big plane can (and has) actually run over a small house and stay relatively intact. So, even if it went up one of the beaches on the spit it might be OK. The biggest threats are running at high speed into an object or terrain feature, or stalling; both of those not happening are largely dependent on the skill and cool nerve of the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aircraft take off, they usually have a steep rate of ascent which would be a stall configuration in unpowered flight, so if the engines fail the pilot has to immediately react to avoid a stall. When this happens, the pilot has to react within a fraction of a second or so. If the pilot panics and pulls back on the stick, it's game over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot is good, they will have an &quot;emergency plan&quot; and will mentally know ahead of time exactly what they will do if they lose power at any given point on any given runway. That plan includes a landing spot. For example, when I fly to a new airport I look at Google Earth and decide where I will land in the case of an emergency during take off. The plan sometimes has to have height thresholds, too. For example, if I lose power at 100 feet I do this, but if lose power at 400 feet I do that. The plan always has a &quot;minimum turnaround altitude&quot;. This is the height where you are safe to do a 180-degree turn and go back to the runway.  Note that the plan has to recalculated every time you fly because of wind. So, if there is a crosswind coming from one direction or another that could affect your choice of emergency landing location.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-07-21T21:52:13.093" LastActivityDate="2015-07-21T21:52:13.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17099" PostTypeId="2" ParentId="17094" CreationDate="2015-07-21T19:58:16.347" Score="3" Body="&lt;p&gt;Cars can in theory suffer from this if humidity is high enough. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth not all planes are carbureted. A solid chunk of airplanes use &lt;a href=&quot;http://www.kal-soft.com/velocity/engine_build.htm&quot; rel=&quot;nofollow&quot;&gt;fuel injection&lt;/a&gt; (mechanical) and &lt;a href=&quot;https://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;FADEC&lt;/a&gt; control is quickly becoming popular. This eliminates the carb ice problem by eliminating the carb all together. Keep in mind that any system needs to be certified for the FAA. There is little reason for a company to spend money developing an anti ice carb system and have it certified when carbs are slowly going away and the ones we still service were certified years ago (&quot;if it ain't broke don't fix it&quot;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth it seems that there are &lt;a href=&quot;http://www.aircraftspruce.com/catalog/inpages/icedetect2.php&quot; rel=&quot;nofollow&quot;&gt;sensor systems&lt;/a&gt; out there for it however I have never used one so I will hold back from commenting on how well they work. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-21T19:58:16.347" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17100" PostTypeId="2" ParentId="17094" CreationDate="2015-07-21T20:28:31.237" Score="6" Body="&lt;p&gt;Not every motorized engine is the same: For example, you would be hard-pressed to find a carbureted car these days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most similar kind of land-vehicle engine you'll find would be a motorcycle engine, and those &lt;em&gt;do&lt;/em&gt; in fact suffer from carburetor ice:&lt;br&gt;&#xA;- &lt;a href=&quot;http://faq.ninja250.org/wiki/What_is_carburetor_ice%3F&quot;&gt;A discussion of carb icing on the Ninja 250&lt;/a&gt;&lt;br&gt;&#xA;- &lt;a href=&quot;http://www.bikechatforums.com/viewtopic.php?t=131792&quot;&gt;A thread about carb ice on Bike Talk Forums&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older cars with carburetors &lt;a href=&quot;http://67-72chevytrucks.com/vboard/showthread.php?t=490674&quot;&gt;were also susceptible to carburetor ice&lt;/a&gt;, and eventually included measures to avoid or mitigate it.&lt;br&gt;&#xA;This could include passive changes such as mounting the carburetor in a warm part of the engine compartment (usually &lt;em&gt;above&lt;/em&gt; the block, in a downdraft configuration), semi-active changes like &quot;heat risers&quot; which would feed warm air into the intake (usually behind the throttle plate, but occasionally in front of it), or fully-active systems like automatic &quot;heat flaps&quot; and &quot;Time/Temperature switches&quot; which do the same thing as the carburetor heat control in an airplane but without the driver's input or control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These systems aren't usually fitted to aircraft as they add both weight and complexity, and can come with their own disadvantages (such as reduced power if the carburetor heat flap is in the &quot;on&quot; (heating) position during takeoff or on a go-around).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So why don't we hear about ground vehicles suffering from carburetor ice as much? Three main reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Carburetor ice is most likely to form at low power settings.&lt;/strong&gt;&lt;br&gt;&#xA;Your car or motorcycle probably doesn't spend much time at or near idle power unless you're stuck in traffic: A few seconds coasting to a stop and then you accelerate away again.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Carburetor ice is less dangerous when you're on the ground.&lt;/strong&gt;&lt;br&gt;&#xA;One of the most common times you'll have a carburetor ice problem is during an approach/landing, with the engine at or near idle power for an extended period of time (this is why many aircraft call for carb heat during landing). Having your engine die at this point is a pretty serious problem, especially if you need to execute a go-around.&lt;br&gt;&#xA;The analog in a car or motorcycle is having your engine stall after spending an extended period idling (standing or stopped in traffic). Having your engine die when you try to accelerate away is inconvenient and will probably make other drivers honk their horns at you and say unkind things, but it's unlikely to kill you.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;There's nothing the driver can do about it.&lt;/strong&gt;&lt;br&gt;&#xA;A driver doesn't usually have a &quot;carburetor heat&quot; handle to pull (except possibly in very old cars), so you can't turn around and say &quot;Your engine stalled because you didn't do this.&quot; On top of that because the problem is usually more inconvenient than dangerous on the ground it's not likely to make news: &quot;Driver had to sit on shoulder for 30 minutes while their carburetor thawed out. Hundreds inconvenienced by rubbernecking traffic.&quot; is simply not as newsworthy as &quot;Airplane crashed!&quot;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-21T20:28:31.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17101" PostTypeId="2" ParentId="2928" CreationDate="2015-07-21T20:35:35.807" Score="1" Body="&lt;p&gt;Here is a &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_surviving_North_American_B-25_Mitchells&quot; rel=&quot;nofollow noreferrer&quot;&gt;list of surviving B-25&lt;/a&gt; which may provide some references. It looks like Redbull has one that they fly around (arguably for business reasons) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/WL3Yq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-21T20:35:35.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17102" PostTypeId="2" ParentId="17094" CreationDate="2015-07-21T20:55:07.590" Score="2" Body="&lt;p&gt;It is because there is no reliable sensor that can detect when and how much ice is or could be present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was some kind of super sensor that could tell if ice was forming in the throat of the carb, then maybe you could have a little computer and a solenoid that would actuate the carb heat, but this would require a lot of development and added complexity that has not been done yet. Also, what if the computer screwed up for some reason and your carb froze?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option would be to have the system automatically turn on the heat any time humidity and temperature reached certain levels. The problem with this is that if either of those (added) sensors failed then you could get iced. Also, the helicopter would be flying inefficiently constantly and burning excess fuel.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-07-21T20:55:07.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17103" PostTypeId="2" ParentId="16947" CreationDate="2015-07-21T21:01:21.313" Score="1" Body="&lt;p&gt;EC155 helicopter. Compared with a conventional blade, the Blue Edge has a tip with both forward and rearward sweep. &#xA;This gives the blade more time to interact with the vortex 'shed' by the rotor, reducing the characteristic impulsive (slap-slap) blade-vortex interaction noise generated by a helicopter.&#xA;The active trailing edge flap harmonises the frequency thus making it quieter.&lt;/p&gt;&#xA;" OwnerUserId="9466" LastActivityDate="2015-07-21T21:01:21.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17104" PostTypeId="2" ParentId="17077" CreationDate="2015-07-21T21:39:27.013" Score="11" Body="&lt;p&gt;A Line Replaceable Unit is a piece of hardware that can be exchanged for a replacement part in a relatively short time by only opening and closing fasteners and connectors. You will find the term LRU in avionics but also in ATC hardware. Examples are FMC, transponder, etc.&lt;/p&gt;&#xA;&lt;p&gt;When you have a complex avionics system you tend to end up with a great variety of LRUs. All these LRU have a very specific function. To be able to quickly replace malfunctioning parts, maintenance needs to keep a large stock of spares for all these LRU's.&lt;/p&gt;&#xA;&lt;p&gt;The Integrated Modular Avionics concept attempts to reduce the variety of LRU's by designing the avionics with common components. E.g. one type of power supply, one type of memory unit, one type of processing board and only a few variations of input/output modules. Instead of working with very function-specific LRUs, the IMU works with more generic Line Replaceable Modules (LRMs). This reduces the number of replacement parts that need to be kept on stock. The LRMs of IMA have more generic functions than in a traditional avionics system.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2020-10-17T20:39:31.903" LastActivityDate="2020-10-17T20:39:31.903" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17107" PostTypeId="1" CreationDate="2015-07-22T01:51:16.290" Score="2" ViewCount="4667" Body="&lt;p&gt;What, if any, endorsement is required to take the Advanced Ground Instructor (AGI) test? &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_135&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.35&lt;/a&gt; does make clear what is required for any knowledge test, but not what is specifically required for the AGI test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also noted that &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1193&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.193&lt;/a&gt; mentioned that flight instructor privileges include providing an endorsement to take the test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1213&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.213&lt;/a&gt; also lists several eligibility requirements to become and Advanced Ground Instructor including taking a knowledge test while mentioning no endorsement which is required to actually take the test.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2018-11-20T21:46:39.397" LastActivityDate="2018-11-20T21:46:39.397" Title="Is any endorsement required to take the Advanced Ground Instructor test?" Tags="&lt;faa-regulations&gt;&lt;ground-instructor&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17108" PostTypeId="2" ParentId="14944" CreationDate="2015-07-22T01:55:36.770" Score="4" Body="&lt;p&gt;While the c17 is twice as big as the A400m by payload and range, the primary reason for using turboprops on the latter is for takeoff from short, unimproved airfields rather than aircraft size. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The four 17ft props on the A400m turboprop can move much larger cylinders of air than can the four 6.5ft fans of the c17. This generates much more thrust when static or moving slowly as in takeoff or landing, particularly important on poor fields. The c17's primary role is strategic, or long distance flight. These are conducted at a higher airspeed where the smaller fan is better suited and large props cause excess drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing claims the c17 can land on unimproved airfields. The reality is that it is so heavy that one or two passes makes anything but concrete unusable, and there is a significant inspection/repair bill anytime they go agricultural.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, Airbus claims the A400m has strategic capability, but payload, speed and range make it an inferior choice.&lt;/p&gt;&#xA;" OwnerUserId="9470" LastEditorUserId="3386" LastEditDate="2015-07-22T02:55:31.590" LastActivityDate="2015-07-22T02:55:31.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17109" PostTypeId="1" AcceptedAnswerId="17112" CreationDate="2015-07-22T01:58:13.217" Score="9" ViewCount="7856" Body="&lt;p&gt;I occasionally see &lt;code&gt;AO2&lt;/code&gt; in the remarks of an automated weather report. What does the AO2 mean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;METAR KSLC 280453Z 00000KT 10SM FEW042 SCT055 BKN080 04/02 A2981 RMK AO2 CIG 037 NW RNWY SLP087 T00440022&lt;/code&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="12720" LastEditDate="2016-01-10T19:44:52.880" LastActivityDate="2018-05-16T09:04:38.097" Title="What does AO2 in the remarks of an ASOS/AWOS mean?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17110" PostTypeId="1" AcceptedAnswerId="17116" CreationDate="2015-07-22T02:03:52.380" Score="8" ViewCount="2778" Body="&lt;p&gt;Mainly because of what pilots learn about density altitude and aircraft performance, any idea that an increase in temperature could improve performance seems counterintuitive. And indeed it is. Here's what got me thinking about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In studying for a written test I ran across a question phrased something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft flying at a constant power setting flies from a colder temperature to a warmer temperature. What happens to true airspeed and true altitude?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The correct answer turned out to be that true airspeed and true altitude both increased. I knew immediately on the altitude because I remembered reading how very cold temperatures can cause dangerous errors in altimeters, but the airspeed didn't make sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I still don't understand why the increased temperature lead to an increase in true airspeed. Obviously a reciprocating engine doesn't perform better in warmer air. We don't install &quot;interwarmers.&quot; Does it really mean that warmer air can actually improve performance? Or does this need a deeper explanation?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="64" LastEditDate="2015-07-22T14:39:52.390" LastActivityDate="2015-07-23T04:09:06.367" Title="Does an increase in air temperature actually improve aircraft performance?" Tags="&lt;aircraft-performance&gt;&lt;performance-calculation&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17111" PostTypeId="2" ParentId="17094" CreationDate="2015-07-22T02:04:53.513" Score="2" Body="&lt;p&gt;Everyone is making the answer more complicated than it needs to be. The manufacturers can't build an automated carburetor deicing system for more than they could sell it for. Therefore, it's a manually actuated system.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2016-02-15T12:40:26.310" LastActivityDate="2016-02-15T12:40:26.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17112" PostTypeId="2" ParentId="17109" CreationDate="2015-07-22T02:11:00.683" Score="11" Body="&lt;p&gt;The &lt;code&gt;AO2&lt;/code&gt; notation means the station is automated and has a precipitation &#xA;discriminator. &lt;code&gt;AO1&lt;/code&gt; means automated but no precipitation discriminator. The precipitation discriminator will be able to sense the difference between rain and snow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The METAR format is documented in the &lt;a href=&quot;http://www.ofcm.gov/fmh-1/fmh1.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Federal Meterological Handbook No. 1&lt;/a&gt; in Chapter 12. This particular notation is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;12.7.1 c.&#xA;  &lt;strong&gt;Type of Automated Station (AO1 or AO2).&lt;/strong&gt;&#xA;  &lt;strong&gt;AO1&lt;/strong&gt;&#xA;   or &#xA;  &lt;strong&gt;AO2&lt;/strong&gt;&#xA;   shall be coded in all METAR/SPECI&#xA;  from automated stations.  Automated stations without a precipitation discriminator shall be identified&#xA;  as &#xA;  &lt;strong&gt;AO1&lt;/strong&gt;&#xA;  ; automated station with a precipitation discriminator shall be identified as &#xA;  &lt;strong&gt;AO2&lt;/strong&gt;&#xA;  .&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="675" LastEditorUserId="12720" LastEditDate="2018-05-16T09:04:38.097" LastActivityDate="2018-05-16T09:04:38.097" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17115" PostTypeId="2" ParentId="17088" CreationDate="2015-07-22T06:43:07.720" Score="2" Body="&lt;p&gt;Part of the gain of coaxial rotors on a helicopter is not having to power the tail rotor (IIRC it takes ~10%). So for contra-rotating propellers and fans, which don't need a tail rotor, the advantage is smaller, about 6–16% [&lt;a href=&quot;https://en.wikipedia.org/wiki/Contra-rotating_propellers#Advantages_and_disadvantages&quot; rel=&quot;nofollow&quot;&gt;1&lt;/a&gt;].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now ducted fans (assuming as used in turbofan engines) usually contain stators. These do not stop the rotation of the flow (that takes away the energy) completely, but they do reduce it significantly and with much lower complexity. The remaining possible gain would probably be at most couple of percent and that is likely not worth the increased complexity and weight of additional gears. Don't forget that turbofans run at significantly higher rotation speeds than propellers.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-22T06:43:07.720" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17116" PostTypeId="2" ParentId="17110" CreationDate="2015-07-22T07:59:27.137" Score="5" Body="&lt;p&gt;Drag (and lift) increases with density. Density decreased and so did drag. So at the same &lt;em&gt;power&lt;/em&gt;, you can fly faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I don't know whether reduction of power of a normally aspirated spark-ignition reciprocating engine at constant &lt;em&gt;throttle&lt;/em&gt; setting would be higher or lower than the reduction of drag. But the question says &lt;em&gt;power&lt;/em&gt; setting.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-22T07:59:27.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17117" PostTypeId="1" AcceptedAnswerId="17118" CreationDate="2015-07-22T09:13:48.487" Score="3" ViewCount="934" Body="&lt;p&gt;There are many kinds of display (LED, LCD, PDP...).&lt;br&gt;&#xA;Which type is used in the in-flight entertainment system on commercial aircraft?&lt;br&gt;&#xA;And which kind of display is used in the electronic flight instrument system?&lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="1467" LastEditDate="2017-12-12T11:08:39.290" LastActivityDate="2017-12-12T11:08:39.290" Title="Which kind of display are used on commercial aircraft?" Tags="&lt;inflight-entertainment&gt;&lt;display&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17118" PostTypeId="2" ParentId="17117" CreationDate="2015-07-22T09:58:12.153" Score="2" Body="&lt;p&gt;Traditionally, it was almost only movie projectors in the cabin, since Cathode Ray Tubes (CRT) were too bulky and impractical to fit. It was also very expensive. I think only with the arrival of LCD displays seatback displays that we know now were made possible.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for cockpit displays, the CRTs were widely used until LCDs were introduced and offered better performance.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You can compare the 737 Classic with retrofitted CRT displays with those of the 737 Next Generation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compare the 747-400 to the 747-8 which had LCD in place of CRT.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can't find pictures, but have been told that the old CRT modules were huge, very deep (which you can't see) and heavy, compare to the thin panel that now is available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can still backwards order CRT for aircraft. I was flying with one airline that had done on a very new A320 to maintain commonality with the rest of the fleet. The pilots didn't appreciate it though, since it was bad for the eyes, needed to be dimmed and had (I believe) inferior resolution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Page 9 of &lt;a href=&quot;http://www.doe.carleton.ca/courses/ELEC4504/display.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; gives some details on the display type tradeoff.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-22T10:56:59.917" LastActivityDate="2015-07-22T10:56:59.917" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17119" PostTypeId="1" CreationDate="2015-07-22T11:58:25.563" Score="5" ViewCount="24451" Body="&lt;p&gt;Assuming that you don't need to have any large piece on the underside dedicated to storage area/people (as all planes do) and you don't care about stability, what is the most energy efficient form for an aircraft in terms of energy required to maintain altitude? I would guess that it is the flying wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it should do:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Use computer control if needed to reduce power requirements&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All other requirements take second place; efficiency is the dominant goal.&lt;/p&gt;&#xA;" OwnerUserId="9475" LastEditorUserId="1467" LastEditDate="2015-07-23T15:39:42.087" LastActivityDate="2017-03-15T17:51:30.237" Title="What is (theoretically) the most efficient shape for an aircraft, assuming you don't have to carry any cargo?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="17120" PostTypeId="1" CreationDate="2015-07-22T12:35:37.480" Score="19" ViewCount="5894" Body="&lt;p&gt;What prevents airline manufacturers from putting a strip of glass along the roof of the aircraft? It would be a good addition in terms of cabin view, light inside the cabin, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it compromise the structural integrity too much?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JUv8E.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JUv8E.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: The image is for representational purposes only. My question does not pertain to a installation similar to this image&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-10-07T14:36:54.503" LastActivityDate="2015-10-07T14:36:54.503" Title="What would prevent the installation of windows on the roof of an airliner?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="4" CommentCount="21" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17121" PostTypeId="2" ParentId="17119" CreationDate="2015-07-22T12:47:02.983" Score="5" Body="&lt;p&gt;For a low speed aircraft, probably just a very long wing, like NASA's &lt;a href=&quot;http://www.nasa.gov/centers/dryden/news/ResearchUpdate/Helios/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helios&lt;/a&gt; research vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/923JP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/923JP.jpg&quot; alt=&quot;Helios prototype, NASA image&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the advantage comes from the tailless design - a tail generates negative lift to aid in stability of the plane. Getting rid of this eliminates some drag but may add control problems!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage is no drag at all from the fuselage - as the question said, we don't want to carry cargo or people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last but not least, there's a large efficiency advantage from the large &lt;a href=&quot;https://en.wikipedia.org/wiki/Aspect_ratio_%28aerodynamics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;aspect ratio&lt;/a&gt; of the wings which reduces losses at the wingtips.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2015-07-23T06:44:03.283" LastActivityDate="2015-07-23T06:44:03.283" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17124" PostTypeId="1" AcceptedAnswerId="17147" CreationDate="2015-07-22T14:00:19.287" Score="10" ViewCount="1514" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolladen-Schneider_LS4&quot;&gt;Rolladen-Schneider LS4B&lt;/a&gt; control connections are automatic. This feature, also called &lt;a href=&quot;http://soaringcafe.com/2011/01/used-sailplane-review-ls3/&quot;&gt;automatic control hookup&lt;/a&gt; seems to be &lt;a href=&quot;https://en.wikipedia.org/wiki/Glider_%28sailplane%29#Glider_design&quot;&gt;common&lt;/a&gt;. The last time I assemble a glider was more than a decade ago, and controls had to be mechanically (re)connected one by one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is automatic control connection? (I imagine it is some mechanism connecting controls when assembling wings). How does it work?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2015-07-22T21:49:04.243" Title="What is automatic control connections and how does it work?" Tags="&lt;flight-controls&gt;&lt;glider&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17126" PostTypeId="2" ParentId="17120" CreationDate="2015-07-22T14:18:56.503" Score="18" Body="&lt;p&gt;The same thing that prevents them from just having glass down the entire length of the fuselage, rather than discrete windows: the ribs of the frame.&lt;/p&gt;&#xA;&lt;p&gt;This picture from &lt;a href=&quot;https://ux.stackexchange.com/a/73296/44852&quot;&gt;cpast's answer on UX.SE&lt;/a&gt; shows how the windows are placed relative to the frame:&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/8cEIl.jpg&quot; alt=&quot;Fuselage section frame&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;On smaller aircraft, they probably could install small windows like the ones beside the passengers in the roof of the aisle, but it would add design complexity and also heat up the cabin (especially when sitting around on the ramp.) I'm assuming the cost/benefit ratio there was just deemed not worthwhile. Having them directly above the passengers wouldn't work because that's where the overhead storage bins are.&lt;/p&gt;&#xA;&lt;p&gt;In the case of wide-body aircraft (like the one picture above,) note that the actual top of the fuselage is quite high. In addition to the overhead storage bins above the passengers, there is often other stuff between the ceiling of the passenger cabin and the actual top of the fuselage, such as crew rest quarters, pipes, cables, or, in the cases of the 747 and the A380, another entire passenger cabin.&lt;/p&gt;&#xA;&lt;p&gt;An additional problem with this is that it would make it harder to control cabin lighting, unless the windows were electrically dimmable, like the new ones on the 787. Longer flights will usually want the passenger cabin to be dark-ish in order to accommodate the passengers who want to sleep. With the windows beside them, passengers can open or close their window depending on how much light they want. That wouldn't work for windows in the ceiling (since they would affect multiple rows of passengers.)&lt;/p&gt;&#xA;&lt;h3&gt;Further Reading&lt;/h3&gt;&#xA;&lt;p&gt;Window size limitations are also discussed in &lt;a href=&quot;https://aviation.stackexchange.com/q/16847/755&quot;&gt;Why aren't airliner windows aligned with their seats?&lt;/a&gt; and &lt;a href=&quot;https://ux.stackexchange.com/a/73296/44852&quot;&gt;the previously-linked question on UX.SE&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-23T21:42:13.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17127" PostTypeId="2" ParentId="17120" CreationDate="2015-07-22T14:20:49.837" Score="25" Body="&lt;p&gt;There are a few factors involved in this and you should check out &lt;a href=&quot;https://aviation.stackexchange.com/questions/16862/what-are-the-factors-behind-increasing-aircraft-window-sizes&quot;&gt;this answer&lt;/a&gt; that touches on window size (same issue really). For what its worth the ceiling is prime real estate on an aircraft. Modern airliners have the over head baggage compartments there (which provide a remarkable amount of space)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M0uCe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M0uCe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The area is also used to run cabling (electronics mostly these days) fore and aft as well as power to the reading lights etc. However it should be noted that these things could most likely be routed along the floor just as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real issue comes back to windows being a weak point and glass being heavy. When it comes to planes you want them to be as light as can be so excess windows will only reduce useful load and increase potential failure points. On top of all that you will have more ambient light in the plane which may bother those trying to sleep on late night flights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want a better view fly an unpressurized plane!&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zFOR5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zFOR5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While on the topic of small bubble canopy planes, anyone that flies GA planes (especially like the ones shown above) with out air conditioning will tell you how hot it gets on the ground (and even at lower altitudes flying) in the summer. The canopies make the inside of plane behave like a green house and really heat up. This would make the inside of a jumbo jet really bake in the summer while taxiing (which can be a long process at big airports).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-07-23T00:46:41.393" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17128" PostTypeId="1" AcceptedAnswerId="17130" CreationDate="2015-07-22T14:21:16.647" Score="10" ViewCount="5225" Body="&lt;p&gt;How do delta wing or flying wing aircraft maintain their pitch attitude in the absence of an elevator? I understand that the ailerons on the wings do control the banking/roll, but they are differential in nature. Then how can they help in pitch control? For pitch control, both control surfaces need to deflect in the same direction.&lt;/p&gt;&#xA;" OwnerUserId="9477" LastEditorUserId="23223" LastEditDate="2019-09-07T12:46:04.970" LastActivityDate="2019-09-07T12:46:04.970" Title="How is pitch controlled in a flying wing?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;flight-controls&gt;&lt;control-surfaces&gt;&lt;flying-wing&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17130" PostTypeId="2" ParentId="17128" CreationDate="2015-07-22T14:47:02.783" Score="16" Body="&lt;p&gt;You basically have the answer right inside of the question (as was mentioned in the comments).  In order to make the plane pitch up and down you have the ailerons move up or down in unison (usually called an &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevon&quot; rel=&quot;noreferrer&quot;&gt;elevon&lt;/a&gt; at that point, again, as noted in comments.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a handy diagram to give you some idea of what we're on about:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/di2Kd.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/di2Kd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the second image the movement of both elevons upwards will pitch the aircraft up as well.  And the elevons going in opposite directions, like the last image, will cause the plane to roll (in this case to the left.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more complex maneuvers as well, like pitching and rolling at the same time. These maneuvers are simply managed by differential deflections of the elevons.  Meaning, if you want to come up and to the left you could leave the right elevon neutral(ish) and pitch the left elevon upwards.  This would push down the left wing, rolling you to the left, and pitch the nose up as well.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-22T15:08:11.577" LastActivityDate="2015-07-22T15:08:11.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17131" PostTypeId="2" ParentId="17110" CreationDate="2015-07-22T14:50:57.150" Score="1" Body="&lt;p&gt;A higher temperature means the molecules are moving faster. Assuming a constant atmospheric pressure, that would translate to less number of air molecules in the same amount of space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, drag is caused by the airframe hitting the air molecules. There is less drag, but the power setting stays the same - i.e. the force of forward thrust is constant, but the force of drag is smaller. Airspeed increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, with most engines, if the &lt;em&gt;throttle&lt;/em&gt; setting stays constant, &lt;em&gt;engine power&lt;/em&gt; is less in warm air. So the question assumes that the loss of power is compensated by an advancing the throttle.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-07-22T14:50:57.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17132" PostTypeId="2" ParentId="17124" CreationDate="2015-07-22T15:00:34.950" Score="6" Body="&lt;p&gt;&lt;em&gt;Automatic control hookup&lt;/em&gt; means that when the wing or tail are fully inserted into the aircraft fuselage, that the control rods for the airlerons, flaps, speedbrakes, elevator, etc., are all guaranteed to be fully and properly connected to the control handles inside the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without automatic control hookups, the control rods coming from the wing or tail control surfaces had to be manually connected, one by one, to the control rods coming from the cockpit. This system led to many accidents, when pilots forgot to connect a control rod during assembly, and they didn't find out until the glider was launched:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NmGWD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NmGWD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.blackmountainsgliding.co.uk/cfidocs/accidentreviewbga12.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.blackmountainsgliding.co.uk/cfidocs/accidentreviewbga12.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another type of manual control rode failure is associated with the &lt;a href=&quot;http://www.dg200.co.uk/hotellier.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;L'Hotellier connector&lt;/a&gt;, which would seem to be fully connected, but would &lt;a href=&quot;http://www.airsailing.org/downloads/safety/Hotellier%20Connectors%20R71.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;fall apart, even after a positive control check&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automatic control hookups are designed to reduce, if not eliminate, these kinds of problems. Needless to say, even with automatic control hookups, a positive control check must still be performed before every flight.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-07-22T15:12:38.003" LastActivityDate="2015-07-22T15:12:38.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17133" PostTypeId="1" AcceptedAnswerId="17137" CreationDate="2015-07-22T15:30:27.380" Score="6" ViewCount="3732" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/j6RmM.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Birds use their strong breast muscles to flap their wings and give them the thrust to move throught the air and fly. In a way, birds use a swimming motion to get the lift needed to fly. Plane wings have a similar shape as bird wings, but instead of flapping their wings, we use engines to thrust them into the air and create the lift needed to fly. (&lt;a href=&quot;https://askabiologist.asu.edu/how-do-birds-fly&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Can we design an aircraft which could also &quot;flap&quot; its wings to fly?&#xA;Yes, we would need fuel to anyways do that.  But, from a design point of view, is it possible to do that?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-07-22T15:56:34.430" LastActivityDate="2019-02-01T09:23:20.897" Title="Can planes flap their wings like birds?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;ornithopters&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17135" PostTypeId="2" ParentId="17119" CreationDate="2015-07-22T15:49:05.857" Score="4" Body="&lt;p&gt;I concur with Andy, but in a few more words: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage of an aircraft provides no lift (or it does so very inefficiently in lifting-body designs), therefore it only contributes to weight and drag. It's a necessary evil in most practical aircraft because the basic idea is to move people or things with the airframe, so a compromise is reached between cargo volume and acceptable fuselage drag. If you instead remove the fuselage, leaving just the wing,  you reduce weight (so less lift is required) and drag (so less thrust is required, which allows smaller engines which are also a contributor to airflow inefficiencies). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the mentality behind Northrop's various &quot;flying wings&quot; (YB-35, XB-49, B-2) as well as NASA's Pathfinder-style aircraft including Centurion and Helios, and certain other designs such as White Knight (the mother ship for SpaceShipOne; it is technically a twin-boom fuselage design not unlike the P-38, but it was intended to minimize fuselage surface area). &lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-22T15:49:05.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17136" PostTypeId="2" ParentId="17133" CreationDate="2015-07-22T15:49:36.640" Score="6" Body="&lt;p&gt;There can be several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airplanes' wings are huge and heavy. Birds' wings are light.&lt;/li&gt;&#xA;&lt;li&gt;A bird's wings are flexible but an airplane's are not.&lt;/li&gt;&#xA;&lt;li&gt;A mechanism to flap an airplane's wings will be a very complex process.&lt;/li&gt;&#xA;&lt;li&gt;A lot more power will be required to flap airplanes' wings (even if flapping wings are designed successfully) than the current jet engines.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The flight will not be as smooth as it is now in airplanes, as a bird constantly moves up and down when it is flapping its wings. This can be seen in this picture of an &lt;a href=&quot;https://en.wikipedia.org/wiki/Ornithopter&quot; rel=&quot;noreferrer&quot;&gt;ornithopte&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5WVl6.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5WVl6.gif&quot; alt=&quot;Flapping wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Did you spot &lt;a href=&quot;https://youtu.be/DBrGeNOxxcE&quot; rel=&quot;noreferrer&quot;&gt;this airplane flying&lt;/a&gt; in the evening sky?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;An interesting article about this: &lt;a href=&quot;http://www.stufftoblowyourmind.com/blog/why-dont-airplanes-have-flapping-wings/&quot; rel=&quot;noreferrer&quot;&gt;Why don't airplanes have flapping wings?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2015-07-22T15:55:49.030" LastActivityDate="2015-07-22T15:55:49.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17137" PostTypeId="2" ParentId="17133" CreationDate="2015-07-22T15:55:29.733" Score="13" Body="&lt;p&gt;From a biological point of view, flapping wings is a viable means of flight. However, this presents some problems when scaled up for human flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One issue is the &lt;a href=&quot;https://aviation.stackexchange.com/q/12182/1696&quot;&gt;square-cube law&lt;/a&gt;: as the wings are scaled up, the area scales as a square (relating to lift), but the volume scales as a cube (relating to weight). This means the wings increase in weight faster than they increase in lift, resulting in less effective wings. The higher weight presents issues in making them flap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/17133/can-planes-fly-like-birds#comment40152_17133&quot;&gt;ratchet freak pointed out&lt;/a&gt; that we do have such machines, and they are called ornithopters. Although there is some potential at smaller sizes (&lt;a href=&quot;http://www.instructables.com/id/3D-Printed-Ornithopter-Micro-UAV-Drone/&quot; rel=&quot;noreferrer&quot;&gt;for small UAV's&lt;/a&gt;), the weight and force issue prevents them from being very useful at larger scales. Ornithopters were some of the &lt;a href=&quot;http://science.howstuffworks.com/transport/flight/classic/ten-bungled-flight-attempt2.htm&quot; rel=&quot;noreferrer&quot;&gt;first unsuccessful designs for heavier than air flight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best solution we have found is propellers. This doesn't work as well as biological propulsion, but it's much easier to spin a prop than flap the whole wing, and works much better for the larger scales we need to move humans. Flapping is also not effective for reaching higher speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see from the biological side that there is a size limitation. The largest birds are much smaller than our airplanes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-22T16:02:21.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17138" PostTypeId="5" CreationDate="2015-07-22T15:57:31.660" Score="0" Body="&lt;p&gt;An &lt;strong&gt;ornithopter&lt;/strong&gt; (from the Greek for &quot;bird wing&quot;) is an aircraft that produces &lt;a href=&quot;/questions/tagged/thrust&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;thrust&amp;#39;&quot; rel=&quot;tag&quot;&gt;thrust&lt;/a&gt; by flapping its &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s, as opposed to a &lt;a href=&quot;/questions/tagged/propeller-aircraft&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;propeller-aircraft&amp;#39;&quot; rel=&quot;tag&quot;&gt;propeller-aircraft&lt;/a&gt; or a &lt;a href=&quot;/questions/tagged/jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet&lt;/a&gt;.  Essentially all of the very first attempts to achieve controlled flight (dating back at least to the eleventh century C.E.) were crude human-powered ornithopters (inspired by the flight of birds, which are not generally amenable to the attachment of external engines), with brave and foolhardy people strapping homemade wings to their arms, jumping from various high places, and usually dying in the process; unfortunately for these would-be pioneers of flight, flapping wings are one of the least efficient methods of generating thrust (due to generating huge amounts of &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt; as they flap), and no human has anywhere near the upper body strength necessary to sustain flight in Earth's atmosphere by flapping their arms (no matter how large the wings attached thereto).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vast majority of flyable ornithopters use some sort of chemical or electrical &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt;, and are generally far too small to carry a human, or any useful amount of &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt;; since ornithopters are considerably less efficient, and far more mechanically complicated to build and operate, than conventional aircraft, there is simply no point in their trying to compete with the latter for most applications.  The main advantage of an ornithopter is its ability to resemble a bird (or, occasionally, a bat, or, for a &lt;em&gt;very&lt;/em&gt; small ornithopter, an insect), which makes them potentially useful for &lt;a href=&quot;/questions/tagged/reconnaissance&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;reconnaissance&amp;#39;&quot; rel=&quot;tag&quot;&gt;reconnaissance&lt;/a&gt; purposes or for scaring away &lt;em&gt;actual&lt;/em&gt; birds (for instance, by airports trying to minimise &lt;a href=&quot;/questions/tagged/bird-strike&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;bird-strike&amp;#39;&quot; rel=&quot;tag&quot;&gt;bird-strike&lt;/a&gt; risk), and, for these purposes, making an ornithopter large enough to carry more than itself and a small camera and &lt;a href=&quot;/questions/tagged/antenna&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;antenna&amp;#39;&quot; rel=&quot;tag&quot;&gt;antenna&lt;/a&gt; would be both unnecessary and counterproductive (people would start getting suspicious if they saw a &quot;bird&quot; the size of a &lt;a href=&quot;/questions/tagged/cessna-172&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cessna-172&amp;#39;&quot; rel=&quot;tag&quot;&gt;cessna-172&lt;/a&gt;, never mind one the size of an &lt;a href=&quot;/questions/tagged/antonov-225&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;antonov-225&amp;#39;&quot; rel=&quot;tag&quot;&gt;antonov-225&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming full circle, there &lt;em&gt;have&lt;/em&gt; actually been a few flyable human-powered ornithopters, but they generally use the pilot's stronger and much-higher-endurance leg muscles, and, even then, typically have flight times measured in seconds (a result of the pilot getting tired).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ornithopter&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="22726" LastEditorUserId="22726" LastEditDate="2019-10-10T03:14:35.210" LastActivityDate="2019-10-10T03:14:35.210" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17139" PostTypeId="4" CreationDate="2015-07-22T15:57:31.660" Score="0" Body="An ornithopter is an aircraft that flies by flapping its wings." OwnerUserId="8482" LastEditorUserId="1696" LastEditDate="2015-07-22T16:11:04.503" LastActivityDate="2015-07-22T16:11:04.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17141" PostTypeId="2" ParentId="17120" CreationDate="2015-07-22T16:12:34.583" Score="10" Body="&lt;p&gt;One other consideration is that the crown of the fuselage is under significant tension*, and glass does not have appreciable tensile strength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Think of the fuselage as a tube being held up midway along its length (i.e., by the wing). The weight of the fuselage and its contents will cause bending about the center wing box, putting the crown in tension, the keel in compression, and the sides under shear. The shear can be channeled around the window frames but normal loads would require far more structure for the same.&lt;/p&gt;&#xA;" OwnerUserId="169" LastActivityDate="2015-07-22T16:12:34.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17142" PostTypeId="2" ParentId="17119" CreationDate="2015-07-22T16:32:02.940" Score="7" Body="&lt;p&gt;The best shape for an &lt;em&gt;airplane&lt;/em&gt; or &lt;em&gt;glider&lt;/em&gt; would look like the &lt;a href=&quot;http://www.alexander-schleicher.de/en/flugzeuge/ash-30-mi/&quot; rel=&quot;noreferrer&quot;&gt;ASH-30mi&lt;/a&gt;, an open class glider with an 86.9ft wingspan, and a 41:1 aspect ratio (wing length to wing chord). It has a glide ratio exceeding 60:1, and is considered the state of the art for gliders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sgaEN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sgaEN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-07-22T16:32:02.940" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17143" PostTypeId="5" CreationDate="2015-07-22T16:53:59.090" Score="0" Body="&lt;p&gt;Uncontrolled airspace or Class G airspace is the portion of the airspace that has not been designated as Class A, B, C, D, or E (or Class F, for countries which use that airspace class). It is therefore designated uncontrolled airspace. Class G extends from the surface to the base of the overlying Class E airspace. Although ATC has no authority or responsibility to control air traffic, pilots should remember there are visual flight rules (VFR) minimums which apply to Class G airspace.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="22726" LastEditDate="2018-05-10T19:54:14.813" LastActivityDate="2018-05-10T19:54:14.813" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17144" PostTypeId="4" CreationDate="2015-07-22T16:53:59.090" Score="0" Body="Class G (uncontrolled) airspace is that portion of airspace not designated as Class A, B, C, D, or E (or Class F, where applicable)." OwnerUserId="2171" LastEditorUserId="22726" LastEditDate="2019-03-02T06:32:00.513" LastActivityDate="2019-03-02T06:32:00.513" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17145" PostTypeId="5" CreationDate="2015-07-22T16:58:42.477" Score="0" Body="&lt;p&gt;Class D airspace is generally airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace is normally designated to contain the procedures. Arrival extensions for instrument approach procedures (IAPs) may be Class D or Class E airspace. Unless otherwise authorized, each aircraft must establish two-way radio communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintain those communications while in the airspace.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-07-22T16:58:42.477" LastActivityDate="2015-07-22T16:58:42.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17146" PostTypeId="4" CreationDate="2015-07-22T16:58:42.477" Score="0" Body="Class D airspace is generally airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower." OwnerUserId="2171" LastEditorUserId="2171" LastEditDate="2015-07-22T16:58:42.477" LastActivityDate="2015-07-22T16:58:42.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17147" PostTypeId="2" ParentId="17124" CreationDate="2015-07-22T17:20:55.137" Score="11" Body="&lt;p&gt;The automatic hookup uses a catchment area to mechanically force the pushrod into a receptacle to ensure a proper mechanical connection when the parts of the plane are connected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, I have sketched below how the ailerons would be connected. The blue structure is the fuselage-side part, and the green structure is the wing-side part of the control linkage. The pushrod coming from the stick is connected to a trapezoidal cone which is hinged at the same point as the wing-mounted pivot lever which is moving the pushrod connected to the aileron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7ghz0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7ghz0.png&quot; alt=&quot;Automatic connector in a cross-section view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The opening of the trapezoidal cone is sized such that the end of the pivot lever will always be caught by it, regardless of the stick position and the aileron deflection. At the base where the end of the pivot lever rests when both parts are connected, the exact position and play between both can be adjusted, so the automatic connection will not have an adverse effect on handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I once witnessed an aborted winch launch of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Akaflieg_Braunschweig_SB-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;SB-8&lt;/a&gt; in which the linkages to the ailerons were interchanged. The pilot noticed the wrong operation of his ailerons before becoming airborne and released the rope quickly, but could not avoid a ground-loop, because he had pushed the low wing into the ground when trying to correct the plane's attitude. I was glad not to have been in his position, because I am not sure I had reacted as quickly. Automatic connections would have made this mishap impossible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-22T21:49:04.243" LastActivityDate="2015-07-22T21:49:04.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17148" PostTypeId="1" CreationDate="2015-07-22T17:26:37.770" Score="1" ViewCount="1878" Body="&lt;p&gt;In the past, we used thin, delta-shaped wings (ogival wings) such as those on the Concorde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These wings can be used up to mach 2.2. Due to high fuel consumption, these wings are no longer used commercially.  However, why can't they be used on fighter aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="167" LastEditDate="2015-07-23T00:19:58.530" LastActivityDate="2019-10-14T03:24:53.747" Title="Why aren't thin, delta-shaped wings used for fighter aircraft?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;propulsion&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17149" PostTypeId="2" ParentId="17128" CreationDate="2015-07-22T17:42:04.367" Score="2" Body="&lt;p&gt;The reason an elevator can cause pitch up/down is by providing a force, pushing down/up, on a point aft of the Center of Gravity (CG).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A canard provides pitch up/down by pushing the nose up/down (forward of CG).  An elevator provides pitch up/down by pushing the tail down/up (note that pushing the tail DOWN pushes the nose UP).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are your elevons (combination elevator/aileron) aft of the CG? If so, pushing both of them down will push the tail up and push the nose down.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastActivityDate="2015-07-22T17:42:04.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17150" PostTypeId="2" ParentId="17148" CreationDate="2015-07-22T17:42:16.903" Score="4" Body="&lt;p&gt;The delta wing was, in fact, very widely used in fighter designs of the mid-late 50s, 60s, and early 70s. The Mirage series (even the latest models) and their derivatives, the MiG-21, the F-106, and the A-4 are some of the more iconic designs to have used the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as time went on, shifting philosophies on aircraft design, along with technological and manufacturing advancement meant that the speed and acceleration attainable with Delta wings could be reached by other means and manufacturers were free to work with other types of wings that don't suffer from the Delta's weaknesses.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-07-22T17:42:16.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17151" PostTypeId="1" CreationDate="2015-07-22T17:48:46.660" Score="1" ViewCount="485" Body="&lt;p&gt;Concorde had engines directly attached to the wings, close to the fuel tanks. Some fuel was evaporated due to heat. What were the reasons to not use pylons or some cooling system to limit this effect?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5Gs2u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Gs2u.jpg&quot; alt=&quot;Concorde&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="3201" LastEditDate="2015-07-30T07:12:03.507" LastActivityDate="2019-04-01T09:34:18.120" Title="Is there a way to avoid fuel loss caused by vaporization from engine heat?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;propulsion&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17152" PostTypeId="2" ParentId="8817" CreationDate="2015-07-22T18:18:15.303" Score="7" Body="&lt;p&gt;You might want to look at the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-2&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-2&lt;/a&gt;.  The leading edge slats are spring-loaded.  If your airspeed falls below about 40 mph, they deploy.  With them deployed and minimal/no power, your speed drops to about 25 mph and your &quot;sink rate&quot; is so low that the aircraft can perform a controlled descent and landing without damaging the gear (depending on the surface you land on, naturally).  The plane has no defined &quot;stall speed,&quot; meaning that you can pass out, pull the controls full aft, run out of fuel and make a relatively uncontrolled descent, yet you might actually survive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to be the closest to what you're asking for.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastActivityDate="2015-07-22T18:18:15.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17153" PostTypeId="2" ParentId="9500" CreationDate="2015-07-22T18:28:18.243" Score="2" Body="&lt;p&gt;Moving the runway further away gives Schiphol the chance to build an extra set of terminals which could connect to the main road. Also, land in Holland is expensive and noise pollution rules are strict, so it was best to build anything new in the middle of a field (an aerial view will show this).&lt;/p&gt;&#xA;" OwnerUserId="9480" LastActivityDate="2015-07-22T18:28:18.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17154" PostTypeId="2" ParentId="751" CreationDate="2015-07-22T18:31:53.610" Score="6" Body="&lt;p&gt;The short answer is that it depends on the airport, and on the day and time of day. Not all Class Bs are equal, and traffic density differs with the seasons and times of day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On paper, SeaTac is fairly quiet for a class B; it sees about 945 operations a day on 3 runways (the third one being recent, opening in late 2008). The problems with the airport are in the ground facilities layout; every terminal that is the origin or destination of a flight at SeaTac is on the east side of the runway complex. That means up to 2/3 of flights require at least one runway crossing during taxi, and with a plane taking off or landing every four minutes on each runway, there's no time to dawdle. Very generous ILS holds due to the varying runway lengths further congest the usable taxiways. One GA pilot, unfamiliar with the traffic flow, can really throw a wrench in the works. As Jason Malinowski said in his answer, if you just want to touch and go they can probably get you in on the newest runway, but if you're planning on parking there you'll likely be staring up at the south end of a passenger jet for a while.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By contrast, an airport like Sky Harbor, which sees 1,200 operations a day on the same number of runways, is more efficiently laid out, with a center passenger terminal complex between the two longest runways, and most GA facilities located to the south of the complex along with cargo and ANG terminals, all conveniently next to 7R/25L (the shortest runway at 7800 feet, more or less reserved for small craft). Sky Harbor therefore tends to be a little friendlier to small singles and twins on XC flights (or just logging Bravo time for a student/rec endorsement).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DFW, larger still (1,800 ops/day), could easily be thought of as two different co-located airports with a common road system. Runway 17L/35R on the east side is specifically intended for use by GA craft including small props, with the other four primary north-south runways serving larger passenger flights (typically the inside runway on each side is for takeoffs and the outside for landings), so provided you can keep pace on the radio you're just fine flying your small prop into DFW (they discourage practice flights though). However, the winds in the area are less constant; when a front from the Gulf brings winds out of the southeast, the entire airport runs on just two auxilliary 13/31 strips. In that situation, the East Tower primarily responsible for GA all but closes to small craft, and nearby Love Field as well as the numerous Class Ds in the Metroplex (Addison, Dallas Exec, Spinks, Meacham, Alliance) see a significant uptick in small props and business jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;O'Hare is just busy; no two ways around it. When the winds are favorable it has four runways on which to handle about 2400 flights a day (that's a plane taking off or landing from each runway &lt;em&gt;every two and a half minutes&lt;/em&gt; on average), and when winds are out of one of the secondary compass points, each of the two usable runways will see a plane rolling down it &lt;em&gt;every 75 seconds&lt;/em&gt;. A quick scan of the complex on Google Earth shows exactly one small twin in the entire complex, at Signature Flight Support toward the northeast. Everything else I see is at least a 50-place regional. They'll work you in if they can, as Fab's answer proves, but I'd be wary of duplicating his flight with the winds out of the southeast. Midway, closer to downtown, does seem to cater more to small props, but even then with Southwest's expanded schedule into this airport I imagine you'd be in for a fairly closely-spaced approach. As a result, I'd say if you were planning a private flight into the Chicago area, you should plan on landing at one of the class Ds, like Chicago Exec, Gary or Waukeegan.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-23T00:31:48.757" LastActivityDate="2015-07-23T00:31:48.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17155" PostTypeId="1" CreationDate="2015-07-22T19:13:54.427" Score="7" ViewCount="1558" Body="&lt;p&gt;In a typical car steering wheel if you release it while the car is in motion, it will return to its center, neutral position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the corresponding situation in an airplane? Is a yoke self centering? Or does it stay put until corrected by the pilot inputs? Let's stick to non autopilot modes to simplify the basic behavior. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The forces on the control surfaces ought to be high when deflected from their default position, right? So I'm assuming that offers a restoring torque? E.g. with the rudder if you take your feet off the pedals then it centers, I think. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some additional points:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;As a simplified case what happens on the ground when the aircraft is stationary. If I deflect the control surfaces to their extreme position &amp;amp; release the yoke would they all return to the neutral position? Is the restoring force gravity or spring loading?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The answers on the other question seem to focus on ailerons but what about elevators?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the rudder typically self center with more alacrity than the other surfaces? Why?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="1360" LastEditDate="2015-07-29T22:30:48.083" LastActivityDate="2015-07-30T02:59:06.317" Title="Are Aircraft yokes self centering in non-auto pilot mode?" Tags="&lt;cockpit&gt;&lt;theory&gt;&lt;control-surfaces&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17156" PostTypeId="2" ParentId="17148" CreationDate="2015-07-22T19:26:44.297" Score="8" Body="&lt;p&gt;Yes, it is. It was used on may 2nd generation designs already mentioned by habu, and it is returning now in the 4.5th generation, now with canards:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;Eurofighter Typhoon:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Eurofighter_Typhoon_line_drawing.svg/1200px-Eurofighter_Typhoon_line_drawing.svg.png&quot; alt=&quot;Eurofighter Typhoon line drawing.svg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;noreferrer&quot;&gt;JAS-39 Gripen:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/JAS39_Gripen.svg/1200px-JAS39_Gripen.svg.png&quot; alt=&quot;JAS39 Gripen.svg&quot;&gt;&lt;br&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;noreferrer&quot;&gt;Dassault Rafale:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Dassault_Rafale_version.svg/1200px-Dassault_Rafale_version.svg.png&quot; alt=&quot;Dassault Rafale version.svg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And occasionally without too:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;noreferrer&quot;&gt;HAL Tejas:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/1/16/LCA_Naval_1.jpg&quot; alt=&quot;LCA Naval 1.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And most of the other designs, while having horizontal tail surfaces, are not really far from that layout either:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot; rel=&quot;noreferrer&quot;&gt;Mig-29 (Su-27 looks very similar and all the newer Russian fighters are derived from either of those two):&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/b/b3/MiG-29_FULCRUM_%28MIKOYAN-GUREVICH%29.png&quot; alt=&quot;MiG-29 FULCRUM (MIKOYAN-GUREVICH).png&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;F-18 Hornet:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/8/88/McDONNELL_DOUGLAS_F-A-18_HORNET.png&quot; alt=&quot;Orthographically projected diagram of the F/A-18 Hornet.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 and F-35 with their negative sweep trailing edge are more of an exception, their layout being governed more by requirement for lower radar cross-section than aerodynamics.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="923" LastEditDate="2015-07-23T00:34:51.013" LastActivityDate="2015-07-23T00:34:51.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17157" PostTypeId="1" AcceptedAnswerId="17160" CreationDate="2015-07-22T20:11:29.200" Score="9" ViewCount="2292" Body="&lt;p&gt;As a private pilot, how do you find information and plan an overnight stay at an airport other than your home airport? For example, where to park, how to get out of the airport?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="65" LastEditDate="2015-07-23T15:54:19.713" LastActivityDate="2015-07-24T13:17:07.613" Title="How do you find information about overnight parking at any airport that is not your home airport?" Tags="&lt;airport&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17158" PostTypeId="2" ParentId="17110" CreationDate="2015-07-22T20:15:45.707" Score="-1" Body="&lt;p&gt;&quot;Obviously a reciprocating engine doesn't perform better in warmer air.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not? Horse Power increases with inlet temperature. Have a look at your engine handbook and look for something like &quot;Sea Level and Altitude Performance&quot;. There should be a chart or table that makes that clear. I'm looking at the chart in my Lycoming engine manual for my Mooney, and the chart clearly shows an increase of horse power with inlet temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;We don't install 'interwarmers.'&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, we don't, but your reasoning is wrong. The premise of the question is that the air temperature changes by itself. By the way, the air pressure increase in a turbocharged/supercharged engine has an increase in air temperature as one component (although the smaller one) to provide for higher engine power. We close the cowl flaps in cruise flight to keep the engine warm, so we get higher engine output when an increase in altitude provides for cooler air to begin with!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Does it really mean that warmer air can actually improve performance?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;yes, but not much. Air density changes (from altitude change) are much more pronounced.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-22T20:15:45.707" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17159" PostTypeId="2" ParentId="17107" CreationDate="2015-07-22T20:19:35.220" Score="3" Body="&lt;p&gt;No endorsement is needed. The AGI and IGI written tests can be done without anyone's endorsement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You also don't need an endorsement to take the CFI, CFII, or FOI written tests, btw.&lt;/li&gt;&#xA;&lt;li&gt;Your reference to 61.193 has nothing to do with this. For one, it's 61.193, not 61.139 (but your link itself is correct), and second, these are not endorsements for written tests. In 61.193 it says &quot;to train and issue endorsements that are required for: ...&quot; and that does not include any endorsements for the AGI, IGI, FIA, FII, and FOI &lt;em&gt;written&lt;/em&gt; tests. Such endorsements, as they pertain to a ground instructor, would, for example, be a 61.217(d) endorsement (not written test).&lt;/li&gt;&#xA;&lt;li&gt;&quot;... flight instructor privileges include providing an endorsement to take the test.&quot; No, they do not. They include providing an endorsement for a ground instructor certificate/licence (not written test), and endorsements for written tests (in general -- not for the ground instructor).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When an endorsement for the written test is needed, then that prerequisites say that explicitly, such as for the PPL, IR, CPL, ATPL, etc., such as in 61.65.(a)(4), for example.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastEditorUserId="9483" LastEditDate="2015-07-22T21:59:38.083" LastActivityDate="2015-07-22T21:59:38.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17160" PostTypeId="2" ParentId="17157" CreationDate="2015-07-22T20:21:28.413" Score="11" Body="&lt;p&gt;Generally, you call the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fixed-base_operator&quot; rel=&quot;nofollow&quot;&gt;FBO(s)&lt;/a&gt; at the airport. They are often listed in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow&quot;&gt;A/FD&lt;/a&gt; or if you want a digital source, &lt;a href=&quot;http://www.airnav.com/airports/&quot; rel=&quot;nofollow&quot;&gt;airnav&lt;/a&gt; has them. If you use &lt;a href=&quot;https://www.foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;Fore Flight&lt;/a&gt;, they will also list many of them. They will also provide you with fuel information as well as anything else you may need to know about the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At smaller airports, you may be limited to a single FBO. At larger airports it's usually worth to talk to all of them (depending on your needs) since there can often be large differences in prices. It should be noted that some FBO's may waive ramp fees if you purchase some minimum quantity of fuel. Some airports may also charge landing fees (which you will pay through the FBO). When I flew out of KPNE there was a $5 a day landing fee (as many TO/LD as you wanted).    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pro Tip:&lt;/strong&gt; the internet is riddled with forums and user groups these days. You may find that a simple &quot;Hey thinking of flying into XXX next weekend&quot; will return you a gaggle of information about the airport and what to do. If you are really lucky, someone may even offer you a spot in their hangar (if they have room).&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-24T13:17:07.613" LastActivityDate="2015-07-24T13:17:07.613" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17161" PostTypeId="2" ParentId="2806" CreationDate="2015-07-22T20:31:36.663" Score="1" Body="&lt;p&gt;Two answers here are &quot;mostly&quot; right, but not exact. What's relevant is IFR vs. VFR, not whether or not it's &quot;commercial&quot;. In IFR it's 1000 ft vertically and 3 miles below 10,000 ft and 5 miles above 10,000 ft. This applies to non-commercial flights as well, such as part 91 flights, this has nothing to do with the flight being &quot;commercial&quot;. And, a commercial flight can also be in VFR, not every commercial flight is IFR. Every airline flight is IFR (part 121), but you can't equate airline operations with commercial flights. I can do a commercial flight under VFR, and I can have the above-mentioned minimums on a non-commercial flight.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-22T20:31:36.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17162" PostTypeId="1" AcceptedAnswerId="17195" CreationDate="2015-07-22T21:51:04.810" Score="8" ViewCount="2423" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11575/at-what-intervals-do-planes-land-and-take-off-from-chicago-ohare&quot;&gt;This older question&lt;/a&gt; asks at what interval planes take off and land from ORD. The accepted answer (one takeoff or landing every 30-40 seconds) jives with my math: 2416 operations a day on average, with winds in a non-cardinal direction all those flights must use just two runways, so worst-case each runway would have a plane rolling along it every 75 seconds round the clock (so a plane takes off or lands from somewhere in the airport every 37.5 seconds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, &lt;em&gt;how&lt;/em&gt;? At that rate, approaching planes would be spaced a scant two and a half minutes apart, and as soon as a landing plane passed over the numbers, a departing plane would be told to line up, then to take off as soon as the landing plane had cleared the runway, and if they hesitate even a few seconds the plane behind them would have to go around. How is this traffic density maintained long-term, especially since, like any airport, it has peak periods of activity exceeding the average?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Follow-up question; is ORD as bad as it gets, or are there &quot;denser&quot; airports with lower total aircraft movements but fewer runways? I heard Heathrow is so bad its airspace is ICAO Class A, prohibiting VFR flights entirely, in part due to the fact the airport handles practically every international flight into London on just two runways.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2018-03-14T00:54:55.670" Title="How does Chicago O'Hare's tower sequence aircraft at peak capacity?" Tags="&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17163" PostTypeId="2" ParentId="1219" CreationDate="2015-07-22T22:50:35.757" Score="1" Body="&lt;p&gt;plain and simple: the brakes. Reverse thrust is &lt;em&gt;much&lt;/em&gt; less effective than brakes. And that's just talking about the force to slow down, not even taking into account that jet engines need a few seconds to spool up (6 or more) and brakes are effective immediately (perhaps 1 s delay).&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-22T22:50:35.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17164" PostTypeId="2" ParentId="738" CreationDate="2015-07-22T23:02:18.483" Score="5" Body="&lt;p&gt;The original poster does not notice that he/she is actually asking two different questions: learn to fly, and learn to become a better pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The value of a sim (any sim!) to learn to fly is VERY (extremely) limited. You get no feeling for the tactile movements and responses in the plane. For that reason the FAA also allows only 2.5 hours credit of sim time (even in an AATD, an Advanced Aviation Training Device) for the PPL, as per AC 61-136. So the value of a desktop sim is even less -- given that the value of even an AATD is so limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The value of using a sim (incl. a desktop sim) to learn to become a better pilot is much higher. And here too, the FAA recognizes this with higher credit in the AC 61-136, such as 20 hours for the IR and 25 hours for the CPL.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-22T23:02:18.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17166" PostTypeId="2" ParentId="9942" CreationDate="2015-07-23T00:55:22.013" Score="1" Body="&lt;p&gt;To add to other answers, vertical stabilizers also have control surfaces on them, and in order to maximize the effect of those control surfaces, you have to have them as far out from the center of horizontal rotation as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why not in front:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stabilizers create drag. Drag is pulling backwards. When they are in the back, that's a natural resting point for them and thus they actually try to keep plane stable in one direction. Move them to the front and you would get a force that constantly tries to turn you butt-first :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Example you can try at home:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine a swinging door. The closer you move the door handle to the hinges, the more force is required to open the door. same applies to the airplane. If you place the rudder in the middle it will mostly push plane to the side instead of turning it.&lt;/p&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2015-07-23T00:55:22.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17168" PostTypeId="2" ParentId="14629" CreationDate="2015-07-23T03:08:46.477" Score="13" Body="&lt;h2&gt;ICAO and FAA CAT III definitions&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A CAT III operation is a precision approach at lower than CAT II minima. Sub-categories are listed below.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A category III A approach is a precision instrument approach and landing&#xA;with no decision height or a decision height lower than 100ft (30m) and a runway&#xA;visual range not less than 700ft (200m).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A category III B approach is a precision approach and landing with no&#xA;decision height or a decision height lower than 50ft (15m) and a runway visual&#xA;range less than 700ft (200m), but not less than 150ft (50m).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A category III C approach is a precision approach and landing with no&#xA;decision height and no runway visual range limitation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;*I've omitted the JAA definitions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/1480.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airbus Flight Operations Support documentation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;FAA Reference Material&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The below links are to comprehensive FAA publications covering the areas as titled. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-29A.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AC120-29 for CAT I/II&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/120.28C.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AC120-28 for CAT III&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Thanks &lt;a href=&quot;https://aviation.stackexchange.com/users/2341/sports-racer&quot;&gt;@Sports Racer&lt;/a&gt; for the comment with links to these documents.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8375" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-10-01T16:52:49.383" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17170" PostTypeId="2" ParentId="17110" CreationDate="2015-07-23T04:09:06.367" Score="2" Body="&lt;p&gt;True airspeed is equivalent airspeed corrected for non-standard pressure and temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a increase in temperature, TAS has no choice but to increase.  Notice that IAS did not increase.  It has nothing to do with engine performance.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-07-23T04:09:06.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17171" PostTypeId="1" CreationDate="2015-07-23T09:41:46.977" Score="5" ViewCount="410" Body="&lt;p&gt;I'm reading &lt;a href=&quot;http://www.aviation-conferences.com/architecture/pdf/ima-henning-butz.pdf&quot;&gt;this paper&lt;/a&gt; about IMA (Integrated Modular Avionics) and I don't get the splitting of the development and integration procedure. In page 4 it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus has to modify the conventional development processes and responsibilities. The IMA system development and integration procedure is split between&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;the Avionic Module Supplier&lt;/li&gt;&#xA;  &lt;li&gt;the Aircraft System Manufacturer&lt;/li&gt;&#xA;  &lt;li&gt;Airbus&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Who is the Aircraft System Manufacturer? Which is its function?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My doubt is principally about this paragraph that is few lines later:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The open IMA concept puts the assembler into the position of the IMA system integrator. The&#xA;  development responsibility for the single systems and their functions remains at the system&#xA;  manufacturers. The avionic module supplier provides “empty” IMA modules to both, the&#xA;  system manufacturers and to assembler. The system manufacturer applies the CPIOM for the&#xA;  local function implementation and qualification. The assembler, in turn integrates the own&#xA;  empty CPIOM with the ADCN on the aircraft in order to establish the basic computing resource&#xA;  for different system functions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="637" LastEditorUserId="17732" LastEditDate="2017-02-08T16:56:22.077" LastActivityDate="2017-02-08T16:56:22.077" Title="How are the system development and integration procedure separated for Integrated Modular Avionics?" Tags="&lt;avionics&gt;&lt;software&gt;&lt;ima&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17173" PostTypeId="1" AcceptedAnswerId="17187" CreationDate="2015-07-23T11:35:50.380" Score="14" ViewCount="4098" Body="&lt;p&gt;If a flight was, say, en route to Seoul, but could only make it to the closest available airstrip and that was Pyongyang, would that be allowed? What would they be met with on the ground?&lt;/p&gt;&#xA;" OwnerUserId="9494" LastEditorUserId="62" LastEditDate="2015-07-23T16:35:40.533" LastActivityDate="2020-04-05T15:42:38.820" Title="In an emergency, can an airliner land at Pyongyang or another North Korean airport?" Tags="&lt;emergency&gt;&lt;international&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17174" PostTypeId="1" AcceptedAnswerId="17176" CreationDate="2015-07-23T11:38:05.757" Score="2" ViewCount="744" Body="&lt;p&gt;Do landing gear wheels continue spinning inside the landing gear compartment once the gear has been retracted or is there a mechanism that will stop them?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-07-23T12:10:51.027" Title="Do wheels continue spinning when gear retracted?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-07-23T12:46:44.703" ContentLicense="CC BY-SA 3.0" />
  <row Id="17175" PostTypeId="2" ParentId="17174" CreationDate="2015-07-23T11:57:29.057" Score="3" Body="&lt;p&gt;They continue spinning but there is a simple friction mechanism that immediately stops them. You can see how it works in &lt;a href=&quot;https://youtu.be/x_yHtfGH0nI?t=650&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; at 10:50.&lt;/p&gt;&#xA;" OwnerUserId="637" LastActivityDate="2015-07-23T11:57:29.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17176" PostTypeId="2" ParentId="17174" CreationDate="2015-07-23T12:10:51.027" Score="2" Body="&lt;p&gt;Some aircraft have little friction skids that slow the wheels down, especially on nosewheels where there are not normally brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On main and body gear, the brakes are (automatically on larger aircraft) momentarily applied during the retraction process to stop them from rotating.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-07-23T12:10:51.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17177" PostTypeId="2" ParentId="17071" CreationDate="2015-07-23T12:52:30.287" Score="1" Body="&lt;p&gt;Vne is defined in terms of True Airspeed (TAS), while all other V speeds are Indicated airspeed (IAS). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders are particularly susceptible to the aerodynamic issues that define Vne because they fly at high altitudes and have long wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since determining true airspeed in the cockpit would require a calculation, gliders have tables in their flight manuals and placards in the cockpit that show Vne in indicated airspeed at various altitudes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jc9KC.jpg&quot; alt=&quot;Vne chart for ASK-21 sailplane &quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lFs0J.jpg&quot; alt=&quot;Vne chart for LET L-33 solo&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/bHLpq.jpg&quot; alt=&quot;Vne chart for Discus B&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-07-23T13:14:02.417" LastActivityDate="2015-07-23T13:14:02.417" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17178" PostTypeId="1" AcceptedAnswerId="17180" CreationDate="2015-07-23T13:59:44.027" Score="38" ViewCount="12285" Body="&lt;p&gt;Can &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/4/4d/SBR_Sextant.jpg&quot;&gt;a sextant&lt;/a&gt; be used while flying? How accurate/reliable is a sextant, both standing still and at 500+ mph? Are sextants found in any cockpits today? &lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="15311" LastEditDate="2020-03-12T07:55:21.957" LastActivityDate="2020-03-12T07:55:21.957" Title="Do pilots need to know how to use a sextant?" Tags="&lt;navigation&gt;&lt;celestial-navigation&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17179" PostTypeId="2" ParentId="17178" CreationDate="2015-07-23T14:26:10.303" Score="5" Body="&lt;p&gt;Yes they can use but no its almost never used anymore and its not a requirement for the PPL or any other license above that here in the US as far as I know. There was at once point a &quot;Flight Navigator Rating&quot; or something to that effect that required knowledge of sextant use.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-23T14:26:10.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17180" PostTypeId="2" ParentId="17178" CreationDate="2015-07-23T14:27:02.190" Score="43" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can a sextant be used while flying?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes it can. Some aircraft like 747 for example had a sextant port to allow celestial navigation.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How accurate/reliable is a sextant, both standing still and at 500+ mph?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sextant is not accurate. At least not accurate enough for today's navigation purposes. You cannot perform a RNP-RNAV approach with a sextant. Per wikipedia, the best accuracy you can get with a sextant is between a tenth to a quarter of nautical mile. But it is a very good alternative if everything else fails.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are sextants found in any cockpits today?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for sextants in modern cockpits, my best guess is you won't find any, at least in the form of one &quot;left in a drawer&quot;. See that image of a sextant being operated on a VC-10. It's more like a submarine periscope than a traditional naval sextant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ygdu9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ygdu9.jpg&quot; alt=&quot;sextant operated on a VC-10&quot;&gt;&lt;/a&gt;&#xA;Retrieved from &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/328339?sa=X&amp;amp;ved=0CBkQ9QEwAmoVChMItLCe5bbxxgIVAt4sCh2hNArF&quot; rel=&quot;noreferrer&quot;&gt;airliners.net&lt;/a&gt; unknown copyright owner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, as KRyan notes and as voretaq7 wrote &lt;a href=&quot;https://aviation.stackexchange.com/a/17186/878&quot;&gt;in their answer&lt;/a&gt;, pilots don't &lt;em&gt;need&lt;/em&gt; to know, but they &lt;em&gt;can&lt;/em&gt; attend training in order to know.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-23T16:42:26.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17181" PostTypeId="1" AcceptedAnswerId="17183" CreationDate="2015-07-23T14:51:00.707" Score="12" ViewCount="2291" Body="&lt;p&gt;After playing a few ATC simulation games, and reading at a few places (don't remember where), I am certain that it is more difficult to manage a larger airliner for the ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose that one A320 and one A380 is trying to land at a certain airport. In another case, if two A320s are queuing up for landing, what extra precautions would the ATC have to take in first case, mainly in separating the aircraft and ensuring that they are on time?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-07-23T16:41:11.290" Title="Why is it more difficult for ATC to manage a larger airliner?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17182" PostTypeId="1" CreationDate="2015-07-23T14:57:49.393" Score="7" ViewCount="295" Body="&lt;p&gt;I was researching information regarding the competitiveness of different government certification organizations (FAA, EASA, etc) and the processes (Amount of time, costs, etc) to get their nations aircraft certified and flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the certification process to get a US jet manufacturer's product into the hands of its customers shorter or longer than other countries? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I've found so far it seems GAMA and other US aviation entities are trying to help shorten/simplify this process in the US. This leads me to believe we are at a competitive disadvantage, but I haven't really found any data to back this up. Any direction helps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Countries/manufacturers that I have been comparing to the US are: Bombardier (Canada), Embraer (Brazil), Dassault (France), and Airbus(France).&lt;/p&gt;&#xA;" OwnerDisplayName="user9308" LastEditorUserId="62" LastEditDate="2015-07-23T15:14:34.987" LastActivityDate="2017-03-15T17:58:02.460" Title="Is the US certification process for airliners shorter or longer than in other countries?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;easa-regulations&gt;&lt;aircraft-certification&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="17183" PostTypeId="2" ParentId="17181" CreationDate="2015-07-23T15:39:27.117" Score="20" Body="&lt;p&gt;They must leave a greater amount of time in between landings/take-offs as the size of the aircraft increases due to &lt;a href=&quot;https://en.wikipedia.org/wiki/Wake_turbulence&quot;&gt;wake turbulance&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were historically 3 classes of aircraft for the purpose of wake turbulance classification&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;H (Heavy)&lt;/strong&gt; aircraft types of 136 000 kg (300 000 lb) or more;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;M (Medium)&lt;/strong&gt; aircraft types less than 136 000 kg (300 000 lb) and more than 7 000 kg (15 500 lb); and&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;L (Light)&lt;/strong&gt; aircraft types of 7 000 kg (15 500 lb) or less.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With the introduction of the A380-800, where it is near MTOW, a fourth category has been added&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Super Heavy&lt;/strong&gt; for Airbus A380-800 with a maximum take-off mass in the order of 560 000 kg&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How much time must be left? Well that depends, for an A380:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Arriving Aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;MEDIUM aircraft behind an A380-800 aircraft — 3 minutes;&lt;/li&gt;&#xA;  &lt;li&gt;LIGHT aircraft behind an A380-800 aircraft — 4 minutes.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Departing Aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3 minutes should be applied for a LIGHT or MEDIUM aircraft and 2 minutes for a non-A380-800 HEAVY aircraft taking off behind an A380-800 aircraft when the aircraft are using:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;the same runway;&lt;/li&gt;&#xA;  &lt;li&gt;parallel runways separated by less than 760 m (2 500 ft);&lt;/li&gt;&#xA;  &lt;li&gt;crossing runways if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1000 ft) below;&lt;/li&gt;&#xA;  &lt;li&gt;parallel runways separated by 760 m (2 500 ft) or more, if the projected flight path of the second aircraft will cross the projected flight path of the first aircraft at the same altitude or less than 300 m (1 000 ft) below.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Source for timings: &lt;a href=&quot;http://www.skybrary.aero/index.php/Airbus_A380_Wake_Vortex_Guidance&quot;&gt;http://www.skybrary.aero/index.php/Airbus_A380_Wake_Vortex_Guidance&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-07-23T15:39:27.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17184" PostTypeId="2" ParentId="17181" CreationDate="2015-07-23T15:45:58.790" Score="5" Body="&lt;p&gt;I wouldn't say more difficult. But it definitely needs extra care. That's mostly for 2 reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Inertia. Bigger aircraft have more mass, more inertia and thus cannot change their kinetic status easily. So ATCOs should have that in mind when vectoring aircraft and should issue commands earlier.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_vortices&quot;&gt;Wingtip vortices&lt;/a&gt;. Wingtip vortices are a function of lift. More lift is needed to keep a heavier aircraft flying, so this aircraft will cause more powerful wingtip vortices. Those can be dangerous and pose a threat for planes landing right behind heavier ones.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-07-23T15:45:58.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17185" PostTypeId="2" ParentId="17181" CreationDate="2015-07-23T15:58:56.667" Score="11" Body="&lt;p&gt;Multiple reasons I can think of (but I'm no pilot so I may be wrong!):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Bigger aircraft are more constrained in terms of which runways they can accept clearances to land on &amp;amp; take off from&lt;/li&gt;&#xA;&lt;li&gt;Bigger aircraft typically need more room to maneuver into holding patterns, change Flight Levels,  make turns etc. &lt;/li&gt;&#xA;&lt;li&gt;Larger aircraft cause more wake turbulence and need to be provided larger separation behind them especially if the following aircraft is much smaller in size&lt;/li&gt;&#xA;&lt;li&gt;Bigger aircraft need longer to slow down and are constrained in which taxiways they can exit via. or whether they will accept LAHSO clearances&lt;/li&gt;&#xA;&lt;li&gt;Bigger aircraft (especially the really big ones) typically have fewer options in terms of parking bays, ramps, tugs etc. that can service them which imposes further restrictions for ramp controllers and ground movements. &lt;/li&gt;&#xA;&lt;li&gt;Bigger aircraft have higher stall speeds in general and higher landing speeds too. So a controller is limited in how much (s)he can ask a Heavy to slow down while executing his plan. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-07-23T16:41:11.290" LastActivityDate="2015-07-23T16:41:11.290" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17186" PostTypeId="2" ParentId="17178" CreationDate="2015-07-23T16:22:51.510" Score="52" Body="&lt;p&gt;Ooh, a celestial navigation question...about airplanes... I never thought I'd see one of these in the 21&lt;sup&gt;st&lt;/sup&gt; century!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the basic question: Pilot training doesn't cover sextant use, but there is still a &quot;Flight Navigator&quot; certificate (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=pt14.2.63&amp;amp;rgn=div5#sp14.2.63.c&quot; rel=&quot;noreferrer&quot;&gt;you'll find it in Part 63 of the FARs&lt;/a&gt;), and an associated &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-18.pdf&quot; rel=&quot;noreferrer&quot;&gt;Flight Navigator Handbook (FAA-H-8083-18)&lt;/a&gt;, last updated in 2011. &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_questions/media/fnx.pdf&quot; rel=&quot;noreferrer&quot;&gt;The written test question bank&lt;/a&gt; is also available if you want an idea of what the FAA expects you to know in order to earn that certificate.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can a sextant be used while flying?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, if you have a clear view of the sky overhead.&lt;br&gt;&#xA;Aircraft used to be designed with &quot;sextant ports&quot; &lt;a href=&quot;https://aviation.stackexchange.com/a/17180/64&quot;&gt;as shown in Stelios' answer&lt;/a&gt;, and special aircraft sextants (indirect-sighting, with a bubble to provide a horizon, and usually some kind of averaging mechanism and timer).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How accurate/reliable is a sextant, both standing still and at 500+ mph? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A sextant is a pretty accurate tool under the right conditions, if you know how to use it. &#xA;Stationary on the ground you can do a surprisingly good job with a sextant, &lt;a href=&quot;https://youtu.be/qMkYlIA7mgw?t=1m43s&quot; rel=&quot;noreferrer&quot;&gt;see for example the US/Canada border monuments&lt;/a&gt;. I'm out of practice, but on calm water I used to be able to fix my position to within about 1 minute of arc (1 nautical mile) on any given line.&#xA;To put that in perspective, that's slightly better navigational performance than a VOR provides at distance (2-4 nautical miles), but substantially worse performance than GPS (within a few feet).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as reliability, the reliability of a ship's sextant is pretty good: much like a mechanical E6B flight computer it'll work fine unless you abuse it (drop, step on, etc.).&lt;br&gt;&#xA;Reliability of an aircraft sextant (or any other bubble sextant with an averaging timer) is not quite as good because there are more moving parts involved, but properly maintained they could be trusted to work when you needed them (and most failures could be compensated for by a decent navigator).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problems with sextants that make them impractical for modern air travel are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Speed&lt;/strong&gt;&lt;br&gt;&#xA;Sextants don't tell you where you &lt;em&gt;are&lt;/em&gt;, they tell you where you &lt;em&gt;were&lt;/em&gt; when you made the observation. The averaging mechanisms I mentioned earlier allow aircraft sextant to partially account for the fact that the aircraft was moving (both vertically and horizontally), but at modern speeds you cover a minute of arc pretty quickly. Radio navigation systems and GPS provide much faster position updates than you could get with a sextant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Complexity of the instrument&lt;/strong&gt;&lt;br&gt;&#xA;Aircraft sextants are precision instruments. They need to be maintained and calibrated or they won't be accurate when you need them, and as I mentioned there are a lot more moving parts to an aircraft bubble sextant than a basic ship's sextant.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Complexity of the process&lt;/strong&gt;&lt;br&gt;&#xA;Using a sextant also require an operator (navigator) who knows what they're doing in order to take the sighting and compute the position, compared to radio navigation (VORs, VOR/DME, or GPS).&#xA;Most pilots don't have any training in using a sextant (my experience comes from sailing), so having one would be useless to them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Weather&lt;/strong&gt;&lt;br&gt;&#xA;While the sextant is a reliable instrument the stars are &lt;em&gt;not&lt;/em&gt; reliable: They're always there, but sometimes they're not visible. You can't see most of the stars &amp;amp; constellations you would take a sighting of during the day (usually only one star is visible), and clouds can obscure them when you want to take a sighting, delaying or preventing your position fix.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are sextants found in any cockpits today?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Certainly not in any light GA cockpit I can think of, and probably not in any single-crewmember cockpit: Even if you held both a pilot certificate and a flight navigator certificate a pilot with their head buried in the sextant is rather useless for &lt;em&gt;actually flying the plane&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would assume that most commercial cockpits also no longer have a sextant as modern jets don't include a sextant port, so there's no way to take a sighting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There might be a few restored vintage aircraft that have a working sextant onboard, but I doubt those are used for practical navigation (they're probably not used at all, except possibly to demonstrate how it was done). &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-07-23T20:50:23.133" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="17187" PostTypeId="2" ParentId="17173" CreationDate="2015-07-23T16:32:16.360" Score="25" Body="&lt;p&gt;I can see at least three questions here and only one of them is fully aviation-related. First, can an airliner legally divert to Pyongyang in an emergency, under the laws of its own country? For US airlines, the answer is yes. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#ap14.2.91.3&quot;&gt;14 CFR 91 SFAR 79&lt;/a&gt; bans flights over North Korea, but does allow an exception in an emergency:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;2. Flight Prohibition&lt;/em&gt;. Except as provided in paragraphs 3 and 4 of this SFAR, no person described in paragraph 1 may conduct flight&#xA;  operations through the Pyongyang FIR west of 132 degrees east&#xA;  longitude.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;4. Emergency situations&lt;/em&gt;. In an emergency that requires immediate decision and action for the safety of the flight, the pilot in command&#xA;  on an aircraft may deviate from this SFAR to the extent required by&#xA;  that emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Second, will North Korea allow the airliner to land? This is a political question, not an aviation one. Either they say yes or they say no. If they say no to an airliner in distress, how will they enforce that? Are they willing to shoot it down rather than let it land? Would that decision depend on the country of the airliner? Can they even make that decision within minutes, or is it already made and they simply initiate a defined procedure? The pilot is probably just going to try to land anyway; assuming the alternative is a crash, he would have little to lose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, what will the 'reception committee' on the ground look like? No idea, this is a political/military question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But practically speaking, this situation should never arise anyway (ignoring movie plot stuff like hacked navigation systems). If your country isn't friendly or at least neutral to North Korea, your airlines simply won't plan flights where the only emergency landing possible is in Pyongyang, and for US carriers specifically it would be illegal anyway.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-23T16:32:16.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17188" PostTypeId="2" ParentId="17173" CreationDate="2015-07-23T16:37:57.280" Score="16" Body="&lt;p&gt;In an emergency that requires landing as soon as possible an aircraft can (and should) land at the nearest suitable airport, laws and international incidents be damned. If your 747 is on fire then being on the ground at an airport in North Korea is preferable to exploding in the air or winding up in the ocean or on the ground somewhere that's &lt;em&gt;not&lt;/em&gt; an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/17187/64&quot;&gt;As Pondlife noted&lt;/a&gt; the regulations prohibiting flight over North Korea contain a specific provision lifting the restriction in the event of an emergency, in addition to FAR 91.3's provision that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Everything else isn't an aviation problem: This is why countries have diplomats (and, if necessary, their armed forces), however as North Korea (or more properly &quot;The Democratic People’s Republic of Korea&quot;) has submitted a &lt;a href=&quot;http://www.icao.int/secretariat/legal/list%20of%20parties/chicago_en.pdf&quot; rel=&quot;noreferrer&quot;&gt;&quot;Notice of Adherence to the Chicago Convention&quot;&lt;/a&gt; they're bound by its requirements, specifically &lt;a href=&quot;http://www.icao.int/publications/Documents/7300_orig.pdf&quot; rel=&quot;noreferrer&quot;&gt;Article 25&lt;/a&gt; which states in part:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each contracting State undertakes to provide such measures of assistance to aircraft in distress in its territory as it may find practicable, and to permit, subject to control by its own authorities, the owners of the aircraft or authorities of the State in which the aircraft is registered to provide such measures of assistance as may be necessitated by the circumstances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are very few circumstances where allowing an aircraft in distress to land would be &quot;not practicable&quot;, though nothing requires them to let the passengers/crew off the aircraft, provide other support services, or make it &quot;convenient&quot; for the passengers &amp;amp; crew to get back home.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="2556" LastEditDate="2017-09-18T08:19:41.913" LastActivityDate="2017-09-18T08:19:41.913" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17189" PostTypeId="2" ParentId="16969" CreationDate="2015-07-23T16:41:22.887" Score="18" Body="&lt;p&gt;If you prefer something more realistic and readily available, go with the fastest business jet, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_Citation_X&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna Citation X&lt;/a&gt;, or if you need a little more range, the &lt;a href=&quot;http://www.gulfstream.com/aircraft/gulfstream-g650&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gulfstream 650&lt;/a&gt;. The Cessna can &lt;a href=&quot;http://www.flyingmag.com/aircraft/fastest-aircraft-top-performers-their-class&quot; rel=&quot;nofollow noreferrer&quot;&gt;cruise at Mach 0.935&lt;/a&gt; over maybe 3000 miles (officially 3460 nm, but certainly a little less when flown at top speed), and the G650 has a range of 6000 nm at Mach 0.925. Thanks to @Lnafziger for helping with the facts. Bonus: Both are useable from a lot more airstrips than any airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flying time from London to New York will be &lt;a href=&quot;http://www.wolframalpha.com/input/?i=flying%20time%20London-New%20York%20at%20Mach%200.935&quot; rel=&quot;nofollow noreferrer&quot;&gt;less than 5 hours&lt;/a&gt; - still quite a bit faster than flying with an airline. By the way, the airliner record on this route is still held by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_VC10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vickers VC-10&lt;/a&gt; with a tad above 5 hours. If you go from London to Boston, the Cessna will have just enough range, for all other routes I recommend the Gulfstream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bureaucratic procedure for making an F-22 available will give your protagonist ample time to cross the Atlantic dozens of times in a business jet. Add to this the stationing of a refueling tanker in the middle of the Atlantic (hint: That alone takes more time than what the F-22 needs to fly the full distance, so its &lt;strong&gt;realistic&lt;/strong&gt; mission time will easily double).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-05-05T20:05:35.663" LastActivityDate="2019-05-05T20:05:35.663" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="17190" PostTypeId="2" ParentId="17120" CreationDate="2015-07-23T17:11:53.470" Score="0" Body="&lt;p&gt;The structural arguments have already been discussed, but a further thing to consider is that there really is no point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the small windows on airliners (necessarily small for the structural reasons outlined) the only person who gets a decent view is the person in the window seat, who has a wide angle view by virtue of being right next to the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The person in the aisle seat (or the centre block of a widebody) is lucky if they catch a glimpse of land out of the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A window on the ceiling of an airliner, besides being to far from anyone to give anyone a decent view, would be be pointing straight up at the sky. All you would see would be blue sky, cloud (under certain weather conditions while below cruise height) and blazing hot sun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recently flew from London to Guanzhou, China, on a 787, on which the designers made the appalling high-tech decision of using dimming windows instead of traditional shutters. The windows don't dim all the way to black, and the sun shining through the window is a real distraction when you're trying to sleep. Who would control the shutters on roof windows in an airliner?&lt;/p&gt;&#xA;" OwnerUserId="1952" LastActivityDate="2015-07-23T17:11:53.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17191" PostTypeId="2" ParentId="14225" CreationDate="2015-07-23T18:05:47.320" Score="9" Body="&lt;p&gt;First of all, if the engine hasn’t been run since 2005, it is likely corroded internally and is junk.  Don’t worry about the logs, that engine will never legally fly on a certified aircraft unless it is overhauled and receives a new logbook.  The other engine and the whole airframe may also be corroded beyond saving.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answering your question more directly: you can buy a new logbook.  Your A&amp;amp;P mechanic must list everything known about the engine from whatever receipts the FBO might have, and he must also verify AD compliance.  An AD is a mandatory &lt;a href=&quot;https://www.faa.gov/regulations_policies/airworthiness_directives/&quot; rel=&quot;nofollow&quot;&gt;Airworthiness Directive&lt;/a&gt; issued by the FAA.  The A&amp;amp;P will verify which ADs apply to that airframe/engine and inspect the plane to insure the work has been done.  After the A&amp;amp;P completes his work for an Annual Inspection, the airframe will be legal to fly.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sitting for 10 years is very bad for engines and airframes.  Be careful going forward.  This plane could be a money pit!&lt;/p&gt;&#xA;" OwnerUserId="9501" LastEditorUserId="2143" LastEditDate="2015-12-21T21:13:59.053" LastActivityDate="2015-12-21T21:13:59.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17192" PostTypeId="1" AcceptedAnswerId="17194" CreationDate="2015-07-23T19:36:49.507" Score="7" ViewCount="8827" Body="&lt;p&gt;What is Electro Hydraulic Servo Valve (EHSV) and Solenoid Operated Valve (SOV)? Also what is the difference between these two valves?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, these two are used to control the hydraulic fluid in actuators. I am working on a aircraft program where SOV are used in Aileron, Elevator &amp;amp; Rudder actuators while EHSV are used in Multi-Function Spoilers [or just spoiler]. I think someone explains these two valve basics would provide me the reason for the selection of these valve to control the hydraulic actuators.&lt;/p&gt;&#xA;" OwnerUserId="685" LastEditorUserId="643" LastEditDate="2015-07-23T20:13:19.167" LastActivityDate="2015-07-23T22:46:55.327" Title="What are Electro Hydraulic Servo Valves and Solenoid Operated Valves?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17194" PostTypeId="2" ParentId="17192" CreationDate="2015-07-23T22:46:55.327" Score="9" Body="&lt;p&gt;A solenoid is an induction-based actuator. In its simplest form it is a magnetic rod inside a coil of wire. Run a current through the wire and you create a magnetic field that creates a force on the rod, moving it one direction or the other. The force with which this occurs is proportional to the current through the inductor (audio speakers use this exact same principle to make the cone vibrate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2sMdG.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2sMdG.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A solenoid-operated valve usually functions as a simple gate; the solenoid mechanism pulls or pushes a simple flat valve allowing the fluid to pass through or not. It's technically possible, but not usually feasible, to use a solenoid as a variable valve; for it to be accurate would require very low friction so the current applied to the solenoid (and thus the force on the valve) could be varied to produce smooth variations in valve position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Solenoid-operated valves are typically used as triggers for larger mechanisms, including the electrohydraulic servo valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An electrohydraulic servovalve uses electrical current to move a &quot;flapper&quot;, similar to a solenoid. The flapper controls the flow of hydraulic fluid to one side or the other of a spool valve. That moves the spool valve, allowing the supply pressure to feed an actuator cylinder, moving it one way or the other. However, that same movement also allows hydraulic pressure to return up to the flapper, providing a countering hydraulic force to the electrical force that moved it, called &quot;negative feedback&quot;. Eventually these forces balance, and the flapper re-centers, closing the spool valve. The net result is that the actuator cylinder has moved a certain set distance, proportional to the strength of the input current.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Uz2Cs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uz2Cs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These valves are used to provide smooth, high-strength motion in a hydraulic system. This type of valve, for instance, can be used to move the control surfaces of a large airliner, without requiring high-pressure hydraulic lines or tensioned cables to link the hydraulic system to the yoke in the cockpit. Instead, the yoke (or sidestick) controls the current through electrical wires leading to the EHSVs. That link is much easier to maintain (and cheaper to build in the first place) than older systems on previous generations of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-23T22:46:55.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17195" PostTypeId="2" ParentId="17162" CreationDate="2015-07-24T05:54:07.123" Score="5" Body="&lt;p&gt;Chicago runs &lt;a href=&quot;http://www.faa.gov/airports/airport_development/omp/faq/runway_utilization/#q3&quot; rel=&quot;noreferrer&quot;&gt;simultaneous triple&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/O%27Hare_International_Airport#Runways&quot; rel=&quot;noreferrer&quot;&gt;parallel approaches&lt;/a&gt;. And as soon as an aircraft clears the runway, another one is allowed to cross the threshold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chicago Tower actually does not do the bulk of the sequencing of aircraft. Chicago TRACON actually sequences the aircraft before they are handed to the Tower. Even before that, Chicago ARTCC begins to sequence inbound aircraft. Similarly, aircraft are handed to departure (TRACON) almost immediately after taking off. Departure procedures are optimized for safety and efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This figure breaks down runway usage percentage for arrivals and departures in April 2015 (7am - 10pm traffic)(&lt;a href=&quot;http://www.oharenoise.org/resources/publications/300-current-anms-report/file&quot; rel=&quot;noreferrer&quot;&gt;source paper&lt;/a&gt;). It highlights the common westbound landing flow with triple parallel runways. You can also see two diverging runways used for the bulk of departures, with sporadic usage of others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dip4j.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dip4j.png&quot; alt=&quot;ORD Arrival and Departure Runway Percentages&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this is all after an airport runway overhaul. Consider that 2014 saw almost a &lt;a href=&quot;https://en.wikipedia.org/wiki/O%27Hare_International_Airport#Traffic&quot; rel=&quot;noreferrer&quot;&gt;10% decrease&lt;/a&gt; in operations from the year 2005. Having talked to controllers that have put in time at Chicago Tower, it is as crazy to handle as humanly possible.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-07-24T05:54:07.123" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17197" PostTypeId="2" ParentId="17178" CreationDate="2015-07-24T07:47:08.460" Score="2" Body="&lt;p&gt;Addressing the first (headline) part of the question; &lt;em&gt;Do pilots need to know how to use a sextant?&lt;/em&gt; I can think of one circumstance where it might come in handy - when you've ditched and are in a raft!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside on sextant accuracy; originally, mariners were sailing from Southampton and trying to find New York. Getting to within a mile of the entrance to the Hudson after sailing 3,000 miles is accurate enough. &lt;/p&gt;&#xA;" OwnerUserId="9189" LastActivityDate="2015-07-24T07:47:08.460" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17198" PostTypeId="1" AcceptedAnswerId="17200" CreationDate="2015-07-24T07:55:55.217" Score="2" ViewCount="1483" Body="&lt;p&gt;Russians often fly the Tu-95 for long distances, &lt;a href=&quot;http://edition.cnn.com/2015/07/23/politics/us-russian-bombers-july-4-intercept/index.html&quot; rel=&quot;nofollow&quot;&gt;in some cases&lt;/a&gt; reaching the California coast. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would happen if they had an engine failure or another emergency Considering the aircraft's age, an emergency is not a very remote possibility. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Would the Tu-95 land in California?&lt;/li&gt;&#xA;&lt;li&gt;Would it rather try to come back home on 3 engines?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8482" LastEditDate="2015-07-30T14:54:47.450" LastActivityDate="2015-07-31T16:47:14.513" Title="What would happen if a Russian TU-95 had an engine failure or other emergency close to the United States?" Tags="&lt;emergency&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17200" PostTypeId="2" ParentId="17198" CreationDate="2015-07-24T08:38:12.907" Score="9" Body="&lt;p&gt;Losing an engine on a 4-engined aircraft is not overly dramatic. In fact the P3 Orion actually intentionally shuts off one engine in flight to conserve fuel- it's more efficient to run three of them at higher power setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I doubt that they would put their aircraft in a position that they could not withstand an engine failure. From Kamchatka to California is it around 6000km max one-way; The TU-95 has a range of 15,000km.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for potential political mess, you can see what happened when a Chinese J-11 Fighter collided mid-air with a US Navy P3 Orion back in 2001 in what is known as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hainan_Island_incident&quot;&gt;Hainan Island Incident&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/542302bfe5274a1317000bd7/Boeing_747-436__G-BNLG_06-06.pdf&quot;&gt;A British Airways 747&lt;/a&gt; lost one engine out of Los Angeles a few years ago, and almost made it all the way to London, but diverted to Manchester (although that event did cause a lot of controversy).&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-24T09:42:15.650" LastActivityDate="2015-07-24T09:42:15.650" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17201" PostTypeId="1" AcceptedAnswerId="17205" CreationDate="2015-07-24T13:29:16.123" Score="20" ViewCount="10240" Body="&lt;p&gt;According to &lt;a href=&quot;https://en.wikipedia.org/wiki/O%27Hare_International_Airport#Pre-deregulation_service&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TWA flew to Europe nonstop from O'Hare starting in 1958&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.gcmap.com/dist?P=ord-lhr%0D%0A&amp;amp;DU=mi&amp;amp;DM=&amp;amp;SG=&amp;amp;SU=mph&quot;&gt;Great Circle Route&lt;/a&gt; distance from &lt;a href=&quot;https://en.wikipedia.org/wiki/O%27Hare_International_Airport&quot;&gt;ORD/KORD&lt;/a&gt; to &lt;a href=&quot;https://en.wikipedia.org/wiki/London_Heathrow_Airport&quot;&gt;LHR/EGLL&lt;/a&gt; is 3953 miles. Other major European airports would have been farther away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What aircraft were capable of making that &lt;strong&gt;non-stop&lt;/strong&gt; flight in 1958 (also, how long would it have taken)? &lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-07-24T16:17:46.780" LastActivityDate="2017-05-16T07:00:55.807" Title="What aircraft could make non-stop transatlantic flights in 1958?" Tags="&lt;aircraft-performance&gt;&lt;aviation-history&gt;&lt;commercial-operations&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17202" PostTypeId="2" ParentId="17201" CreationDate="2015-07-24T13:38:47.943" Score="17" Body="&lt;p&gt;In 1958, Trans World Airlines operated primarily &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Constellation&quot;&gt;Lockheed Constellation&lt;/a&gt;. Its range is listed as 4,700 nmi, which makes it suitable for that route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Trans_World_Airlines&quot;&gt;Wikipedia page about TWA&lt;/a&gt; lists when they &lt;a href=&quot;https://en.wikipedia.org/wiki/Trans_World_Airlines#Retired_fleet&quot;&gt;introduced and retired each type&lt;/a&gt;. According to that table the only long range aircraft they had in 1958 was Constellation; B707 only being introduced in 1960.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar aircraft that were in service by 1958 with other airlines and had over 4,000 nmi range that is needed for the route were &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-6&quot;&gt;Douglas DC-6A and B&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-7&quot;&gt;Douglas DC-7&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot;&gt;Boeing 377&lt;/a&gt; and already turboprop &lt;a href=&quot;https://en.wikipedia.org/wiki/Bristol_Britannia&quot;&gt;Bristol Britannia&lt;/a&gt;. But TWA did not have any of those types, so they were not used on that particular route.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-07-24T14:04:57.213" LastActivityDate="2015-07-24T14:04:57.213" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17203" PostTypeId="1" AcceptedAnswerId="17204" CreationDate="2015-07-24T14:31:47.390" Score="20" ViewCount="5154" Body="&lt;p&gt;I just heard about &lt;a href=&quot;http://www.dailymail.co.uk/indiahome/indianews/article-3127050/US-flight-makes-shocking-U-turn-IGI-Government-officials-allegedly-United-Airlines-REVERSE-taxiing-plane-IGI-two-mystery-men-board.html&quot;&gt;this&lt;/a&gt; 4 month old incident, where a United Airlines B777 made a U-turn, while it was on way to runway. What is the turning radius required to make such a U-Turn? Also, is so much space available near the taxi area at the IGI Airport? At last, is this a common practice for airliners to do?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2015-07-24T14:37:14.037" LastActivityDate="2016-04-13T07:12:20.870" Title="How could an airliner as big as B777 make a U Turn on ground?" Tags="&lt;airliner&gt;&lt;taxiing&gt;&lt;boeing-777&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17204" PostTypeId="2" ParentId="17203" CreationDate="2015-07-24T14:46:35.733" Score="29" Body="&lt;p&gt;&lt;strong&gt;Turning Radius, as found in a planning document:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;28.7m for a Boeing 777-200&lt;/li&gt;&#xA;&lt;li&gt;34.7m for a Boeing 777-300&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Rotating around one a point a bit off the wing to allow both wheels to roll throughout.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Minimum Pavement Width&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;47.5m for a Boeing 777-200&lt;/li&gt;&#xA;&lt;li&gt;56.0m for a Boeing 777-300&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M5PH7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M5PH7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c6qL5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c6qL5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://sydney.edu.au/engineering/aeromech/AERO2703/Resources/Boeing777_200.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Be aware that this is not exactly ideal- visibility from the flightdeck is not great and you do not want the gear running into the grass or edge lights. An &lt;a href=&quot;http://avherald.com/h?article=4868e523&amp;amp;opt=0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Emirates A380&lt;/a&gt; screwed up in Warsaw not too long ago when trying to pull this stunt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this width is not normally provided by the runway (even Heathrow only has 45m and 50m runway width), you will add turning pads at the end unless there are taxiways you can use instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://zoek.officielebekendmakingen.nl/stb-2010-632-003.png&quot; alt=&quot;Source&quot;&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://zoek.officielebekendmakingen.nl/stb-2010-632-003.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-25T08:40:21.933" LastActivityDate="2015-07-25T08:40:21.933" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17205" PostTypeId="2" ParentId="17201" CreationDate="2015-07-24T15:50:06.653" Score="18" Body="&lt;p&gt;The first scheduled trans-atlantic air service was made possible with &lt;a href=&quot;https://en.wikipedia.org/wiki/Transatlantic_flight#Early_notable_transatlantic_flights_and_attempts&quot; rel=&quot;noreferrer&quot;&gt;Zeppelins&lt;/a&gt;. The LZ-127 started flying the route in 1931, mostly to &lt;a href=&quot;https://en.wikipedia.org/wiki/Lakehurst_Maxfield_Field&quot; rel=&quot;noreferrer&quot;&gt;Lakehurst, NJ&lt;/a&gt;, or Pernambuco in Brazil, but was disassembled in 1940.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first airliner which was able to cover the distance (back then it was Berlin - New York) was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_200_Condor&quot; rel=&quot;noreferrer&quot;&gt;Focke-Wulf 200&lt;/a&gt;, which in 1938 needed almost 25 hours East-West and 20 hours on the return leg. With its slow cruise speed, wind made a lot of difference. Sadly, the US did not allow Lufthansa to start the scheduled service it had planned to open in 1939. Lufthansa had opened regular air mail services in 1934 between Europe and South America using flying boats and a relay ship in the middle of the Atlantic. Air France added its transatlantic mail service flying from Africa to South America and back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first heavier-than-air transatlantic passenger service opened between New York and Marseille in 1939 on &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_314_Clipper&quot; rel=&quot;noreferrer&quot;&gt;Boeing 314 Clippers&lt;/a&gt; operated by Pan Am. It crossed the Atlantic between Foynes, Ireland and Botwood, Newfoundland. A British service, also using flying boats, was in preparation but stopped by the beginning of WW II.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1950s, there were already several options for transatlantic air travel, but none of them non-stop from Chicago: Pan Am, TWA, Trans Canada Airlines (TCA), BOAC (successor of Imperial Airways), and Air France all operated large propeller aircraft which covered the distance with refueling steps, typically in Gander (Newfoundland) and Shannon (Ireland). Typical aircraft were the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-4&quot; rel=&quot;noreferrer&quot;&gt;Douglas DC-4&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-6&quot; rel=&quot;noreferrer&quot;&gt;DC-6&lt;/a&gt;, and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Constellation&quot; rel=&quot;noreferrer&quot;&gt;Lockheed 149 Constellation&lt;/a&gt;, but also the French &lt;a href=&quot;https://en.wikipedia.org/wiki/Lat%C3%A9co%C3%A8re_631&quot; rel=&quot;noreferrer&quot;&gt;Latecoere 631&lt;/a&gt; flying boat was used until 1955. Of these airlines, only &lt;a href=&quot;https://en.wikipedia.org/wiki/O%27Hare_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Pan Am and BOAC serviced O'Hare&lt;/a&gt; in 1957, before the first international terminal opened there in the following year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still, the prevailing eastward wind made the East-West crossing hard and required airlines to reduce payload, and only the advent of faster  airliners like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-7&quot; rel=&quot;noreferrer&quot;&gt;Douglas DC-7&lt;/a&gt; (from 1956) and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1649_Starliner&quot; rel=&quot;noreferrer&quot;&gt;Lockheed 1649 Starliner&lt;/a&gt; (from 1957) made the transatlantic services more reliable and economical. Beginning with the DC-7C, their range was sufficient to support transatlantic service directly from Chicago O'Hare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In October 1958 the first transatlantic jet airliner service was opened by &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Overseas_Airways_Corporation&quot; rel=&quot;noreferrer&quot;&gt;BOAC&lt;/a&gt; using the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;noreferrer&quot;&gt;de Havilland Comet 4&lt;/a&gt;, followed shortly after by Pan Am, operating the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;noreferrer&quot;&gt;Boeing 707&lt;/a&gt; and connecting London with New York (with an occasional refueling stop at Gander on westbound flights). O'Hare could only participate in this progress after its main runway was extended to &lt;a href=&quot;http://airwaysnews.com/blog/2014/04/07/chicago-ohare-history/&quot; rel=&quot;noreferrer&quot;&gt;accommodate large jets in June 1960&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, the most likely airplanes to fly transatlantic directly from O'Hare would have been the DC-7C (but &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Douglas_DC-7_operators&quot; rel=&quot;noreferrer&quot;&gt;operated by Pan Am&lt;/a&gt;, not TWA), the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1049_Super_Constellation&quot; rel=&quot;noreferrer&quot;&gt;Lockheed L-1049G&lt;/a&gt; and the L-1649, which both were operated by TWA. For the flying time, the &lt;a href=&quot;http://www.airmilescalculator.com/distance/jfk-to-ory/&quot; rel=&quot;noreferrer&quot;&gt;3628 miles from JFK/Idlewild to Paris Orly&lt;/a&gt; took 14¼ hours with the DC-7C and 14.83 hours with the Lockheed 1649. So it is fair to assume a flying time of 15½ to 16 hours for the slightly longer distance between Heathrow and O'Hare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quote from &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1649_Starliner&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In January 1958 Pan American scheduled the DC-7C from Orly to Idlewild&#xA;  in 14 hr 15 min; TWA scheduled the 1649 in 14 hr 50 min.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-05-16T07:00:55.807" LastActivityDate="2017-05-16T07:00:55.807" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17206" PostTypeId="1" CreationDate="2015-07-24T17:10:43.803" Score="1" ViewCount="265" Body="&lt;p&gt;We are using blunt shaped nose in blended wing,instead of blunt,if we use needle shaped nose what would happen ,it reduce shockwave or it produce bow shock?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastActivityDate="2015-10-04T11:25:58.730" Title="what would happen if we use needle shaped nose in blended wing?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17207" PostTypeId="1" AcceptedAnswerId="17210" CreationDate="2015-07-24T17:33:56.087" Score="11" ViewCount="1318" Body="&lt;p&gt;In reading online, I've come across the term &quot;pencil-whipping&quot;. The actual term is new to me but I'm familiar with the practice; it's when someone fills out the paperwork that attests something is true, without actually verifying it himself (at least not to the standards required). Technically that's fraud, but it's also usually a &quot;who'll watch the watchmen&quot; situation; if you don't know what the guy is required to do and watch him do it, or else call in a second opinion, you won't know anything's been skipped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I purchased a home a few years ago, and the home inspector did a good job of finding the things we'd have to get fixed. If he hadn't though, State of Texas requires these inspectors to have &quot;errors and omissions insurance&quot; on top of a &quot;general liability&quot; policy. If the inspector said he has checked something though he didn't; or he made a mistake checking it; or he didn't check something he was supposed to, he and his insurer are liable for any damages resulting from the new homeowner trusting that report. This generally discourages pencil-whipping in the home buying industry, as after the first instance of the insurer having to pay out for an electrical fire caused by an outlet the inspector attested to be fine, the guy's likely out of a job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question here is, do A&amp;amp;Ps in the United States carry a similar liability? If I were to hire a guy and pay him thousands of dollars for a pre-purchase inspection of an aircraft, get the all-clear, buy it and then find out the aircraft actually isn't airworthy because of something he missed, what recourse do I personally have against the inspector? How would I report this misfeasance and to whom? Assuming nobody was hurt and I just have a loan payment on a museum piece (or a fat unexpected repair bill), what damages can I claim?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-24T22:02:05.100" LastActivityDate="2015-07-24T22:02:05.100" Title="What liability does an aviation inspector have for errors &amp; omissions?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;liability&gt;&lt;airworthiness&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17209" PostTypeId="2" ParentId="17207" CreationDate="2015-07-24T19:52:00.997" Score="5" Body="&lt;p&gt;I only can speak for Canada but we use much of the American regulations in Canada as part of our regulations. In Canada, all mission critical systems Ie flight control systems etc ... have to be signed off by 2 inspectors for a total of 3 people working on the system. The maintenance engineer will sign of there own work and the inspector will sign off the inspection. A second inspector will sign off the secondary inspection. So typically if there is an error one person is typically not solely responsible for it. Additionally all inspectors and maintenance engineers licenses are only valid while working for a maintenance organization AMO. The organisation's insurance typically covers the employees working for them. When I went through my licensing I was told that we could still be held liable for criminal prosecution if we were willfully negligent. It was explained to us this only incurred once previously.  If memory serves me correctly it was the mechanic responsible for a plane that went down in the Florida everglades.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2015-07-24T19:52:00.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17210" PostTypeId="2" ParentId="17207" CreationDate="2015-07-24T20:23:38.383" Score="4" Body="&lt;p&gt;There's a good article on this question for the US &lt;a href=&quot;http://www.avweb.com/news/savvyaviator/savvy_aviator_51_mechanics_liability_196570-1.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; (you mentioned Texas). The relevant FAR is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7322923d0271c25d7cbc643657d59771&amp;amp;mc=true&amp;amp;node=se14.1.43_112&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 43.12&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§43.12   Maintenance records: Falsification, reproduction, or alteration&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a) No person may make or cause to be made:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Any fraudulent or intentionally false entry in any record or&#xA;  report that is required to be made, kept, or used to show compliance&#xA;  with any requirement under this part;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, no pencil whipping. And if you do it and get caught, then the FAA can suspend or even revoke your &lt;a href=&quot;https://www.faa.gov/mechanics/&quot; rel=&quot;nofollow&quot;&gt;A&amp;amp;P certificate&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, that's only part of the story. The FARs say nothing about civil liability and state law. Even if a mechanic does everything correctly according to the FARs, someone can still sue him if they believe they have a civil case for negligence (just like suing a doctor or any other professional).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that's where this question probably becomes unanswerable on this site: local (state) law will determine what - if any - liability the mechanic has. In the end it will come down to what's in your contract with the A&amp;amp;P, what your state laws on professional liability are, and what the specific circumstances of your case are.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-24T20:23:38.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17211" PostTypeId="1" CreationDate="2015-07-24T21:38:27.660" Score="1" ViewCount="614" Body="&lt;p&gt;On Engine Out Operation in Boeing Airplanes, which altitude is preferable, the OPT Altitude, the MAX Altitude or the RECOM Altitude of the ENG OUT CRZ Page?&lt;/p&gt;&#xA;" OwnerUserId="9511" LastEditorUserId="19" LastEditDate="2016-08-12T10:59:03.373" LastActivityDate="2016-08-12T10:59:03.373" Title="Which cruise altitude is prefered in engine-out operations of Boeing airplanes?" Tags="&lt;engine-failure&gt;&lt;altitude&gt;&lt;cruise&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17212" PostTypeId="2" ParentId="17211" CreationDate="2015-07-24T21:51:37.507" Score="5" Body="&lt;p&gt;You'd typically drift down to your max single-engine altitude, which means essentially that max continuous power on the operating engine is sufficient for level flight at that altitude.  Higher than that, you have a slow descent going in order for the thrust you have to maintain the recommended driftdown airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, there wouldn't be any advantage to descending lower than this until you need to do so for approach and landing, so you'd probably remain at that max altitude.  As you burn off fuel, your max engine-out altitude would &lt;em&gt;slowly&lt;/em&gt; increase so (hypothetically) you could actually step-climb up a little bit if you were going to be at that new Single Engine cruise altitude long enough, but in practice you'd need to lose the engine a LONG way from landing before the idea of step-climbing up to a higher SE cruise altitude would make practical sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;Max&quot; altitude is only reachable with the thrust of 2 engines, and the &quot;OPT&quot; altitude is probably well above what your max SE altitude is anyway -- it's optimum for cruising &lt;strong&gt;&lt;em&gt;with both engines operating&lt;/em&gt;&lt;/strong&gt;, after all.  Granted, a sufficiently high Cost Index and/or strange winds can pull the Optimum altitude down, but in 99% of the cases, Optimum is going to be well above Max Single Engine altitude.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-24T21:51:37.507" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="17213" PostTypeId="1" CreationDate="2015-07-24T22:17:21.523" Score="12" ViewCount="6361" Body="&lt;p&gt;I have completed EASA Part 66 B1.1 exam modules (some from the UK CAA and some from the German 147 organisation).&lt;/p&gt;&#xA;&lt;p&gt;My queries are:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Can I apply to any member state (e.g., Belgium, The Netherlands, Germany, Ireland, UK, etc.) to get my initial Part 66 licence?&lt;/p&gt;&#xA;&lt;p&gt;I have already emailed few country’s licensing departments; they declined and advised me to apply only to the UK CAA.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If I can apply to any member state, why did I get these replies? If I can’t, why not?&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does it affect job prospects in the UK if someone has a Part 66 license issued by another European country? (And vice versa?)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To which authority (country) can I apply to get my Part 66 licence as soon as possible if I am eligible to do so.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does it affect aircraft type rating endorsement in future on a Part 66 licence? For example, if my license is issued from Belgium but I’m working in the UK.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9512" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2021-01-12T08:29:05.997" Title="Does it matter in which country I obtain my EASA Part 66 AME licence?" Tags="&lt;aircraft-maintenance&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17216" PostTypeId="1" AcceptedAnswerId="32604" CreationDate="2015-07-25T01:30:42.840" Score="5" ViewCount="1346" Body="&lt;p&gt;I have experienced this a few times in the last couple of months. When the ATC assigns me a squawk code and I enter it in the transponder, a few minutes later when I try to reconfirm the squawk code, they give me a new code. I know that they can see me on the radar anyway, just may not identify me positively. I noticed this more on an inbound flight to a towered airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This happened yesterday too. I was assigned to squawk 6451. I replied to confirm it and entered it in the transponder. While holding short for takeoff, when I asked the controller to reconfirm the code, he said that it is 6455.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the controller's responsibility if they confirm an incorrect read back? Since this happened to me several times, I am concerned if such incident can impact safety, traffic advisories or aircraft separation?&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="65" LastEditDate="2015-07-27T14:04:17.330" LastActivityDate="2016-10-22T08:37:12.750" Title="Is it ATC's responsibility to ensure read backs are correct?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17218" PostTypeId="2" ParentId="17216" CreationDate="2015-07-25T02:13:54.593" Score="6" Body="&lt;p&gt;A controller, should be on the lookout for all incorrect readbacks. But controllers are human, and can easily miss them, or say things in correctly. Incorrect squawk codes are often more of an annoyance versus an actual separation issue. It'd become an issue if they didn't take action when it was noticed that there was an incorrect code airborne, and let you truck on your way and not perform appropriate handoffs or inform others of any issues with your flightplan/target.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the time, an incorrect beacon code will be flashing on the scope, if it's not assigned to someone else, and the controller will look through their list to find the correct code. If you tag up under someone else's code, then it becomes more of an issue, as they have to realize it's incorrect, suspend the datablock, and flightplan(or most likely drop it out of the system and reenter it) (flightplan issue is often delegated to others in the operation), and hunt for your correct code.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-07-25T02:13:54.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17219" PostTypeId="5" CreationDate="2015-07-25T02:53:36.063" Score="0" Body="" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-25T02:53:36.063" LastActivityDate="2015-07-25T02:53:36.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17220" PostTypeId="4" CreationDate="2015-07-25T02:53:36.063" Score="0" Body="Oh, you know, things that make you smile and laugh?  Jokes?  Ridiculously bad answers that appear to have been written by a squirrel on acid?  No?  Not ringing any bells?  Eh, you're not alone." OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-25T02:53:36.063" LastActivityDate="2015-07-25T02:53:36.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17221" PostTypeId="1" CreationDate="2015-07-25T05:18:39.750" Score="10" ViewCount="3660" Body="&lt;p&gt;I'm thinking of trijets like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-154&quot;&gt;Tu-154&lt;/a&gt;, which has three jet engines in the rear. Not something like &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot;&gt;L-1011 Tristar&lt;/a&gt; which has only one engine at the rear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-154:&lt;br&gt;&#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f5/Tupolev_Tu-154B-1%2C_Tarom_AN0193531.jpg&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f5/Tupolev_Tu-154B-1%2C_Tarom_AN0193531.jpg&quot; alt=&quot;Tu-154&quot;&gt;&lt;/a&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-154&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;L-1011 TriStar:&lt;br&gt;&#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/9/94/Lockheed_L-1011-1_Tristar%2C_Lockheed_JP5893645.jpg&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/94/Lockheed_L-1011-1_Tristar%2C_Lockheed_JP5893645.jpg&quot; alt=&quot;L-1011&quot;&gt;&lt;/a&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do these kinds of jets have T-tails? Maybe the side jets get in the way of a conventional tail, but it looks to me like you could just raise those engines a little bit and enough room would appear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that T-tails add complexity. The vertical part of the tail has to be strengthened (more weight) since it undergoes more forces. So a conventional tail seems preferable.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="5517" LastEditDate="2015-07-25T20:05:03.030" LastActivityDate="2019-07-18T15:05:39.873" Title="Why do trijets (3 rear engines) usually have a T-tail instead of a normal tail?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17222" PostTypeId="2" ParentId="17203" CreationDate="2015-07-25T05:30:44.260" Score="3" Body="&lt;p&gt;The longest 777 s have  steerable wheels on the mains and also a GMCS (ground cam showing the wheels) to assist pilot. If you want to make the smallest turn with an aircraft you have to use differential braking and asymmetrical thrust: Press hard on the toe brake on the side you want to turn, tiller full deflection and increase thrust on the opposite side. However this is some stress on the tyres and landing gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data are available on that link, section 4.2 &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/777_2lr3er.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.boeing.com/assets/pdf/commercial/airports/acaps/777_2lr3er.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8331" LastActivityDate="2015-07-25T05:30:44.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17223" PostTypeId="1" CreationDate="2015-07-25T10:17:03.357" Score="8" ViewCount="2101" Body="&lt;p&gt;What is the highest age at which you can decide to become a pilot for a major airline, a pilot for a cargo airline, or a private pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to know for Canada or France mainly. But I wonder whether these countries will have rules that are too different from the US and EU.&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="39" LastEditDate="2015-07-26T03:19:30.813" LastActivityDate="2017-10-18T20:42:10.413" Title="How old is too old to become a pilot?" Tags="&lt;pilots&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17224" PostTypeId="1" AcceptedAnswerId="17225" CreationDate="2015-07-25T10:35:28.767" Score="2" ViewCount="119" Body="&lt;p&gt;I am thinking of changing my career. I have a physics degree and I want to do a masters in aviation management.Is there any sites where can I get an idea about my chances at getting a job in the aviation management sector, if I do a masters? (with no prior experience).&lt;/p&gt;&#xA;" OwnerUserId="9518" LastActivityDate="2015-07-25T18:46:57.557" Title="Where can I ask questions (career advice) about jobs in Aviation Management?" Tags="&lt;aircraft-design&gt;&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-07-25T14:28:29.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="17225" PostTypeId="2" ParentId="17224" CreationDate="2015-07-25T11:03:07.287" Score="2" Body="&lt;p&gt;There is a huge demand for aviation professionals. However, how that demand is looks like is very difficult to answer, since it's a pretty fragmented market and getting an overview is very difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As such, you're best chances of understanding it are:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Going to recruitment fairs that major airlines attend.&lt;/li&gt;&#xA;&lt;li&gt;Attending events that airlines hold themselves.&lt;/li&gt;&#xA;&lt;li&gt;Trying to get in touch with human resources in an appropriate way directly.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From this you should be to gauge how interesting a candidate you will be. As with most things, this is hardly an exact science. Getting a program with a placement/internship as part of the course for instance might be quite beneficial. As for the no previous experience, I think this is the case for most people heading into this area.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-25T18:46:57.557" LastActivityDate="2015-07-25T18:46:57.557" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17226" PostTypeId="2" ParentId="17221" CreationDate="2015-07-25T14:28:18.197" Score="3" Body="&lt;p&gt;Complexity. The worst possible design would be like this: Horizontal and vertical stabilizers are mounted to an engine each...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you triple the maintenance difficulties you have with a MD-11 or DC-10. And you want an easy access to the engines as possible - which requires enough space.&lt;/p&gt;&#xA;" OwnerUserId="2147" LastActivityDate="2015-07-25T14:28:18.197" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17228" PostTypeId="1" AcceptedAnswerId="17229" CreationDate="2015-07-25T16:00:54.713" Score="2" ViewCount="97" Body="&lt;p&gt;Is the United Kingdom subject to the EASA's authority or the CAA's (Civil Aviation Authority) authority?&lt;/p&gt;&#xA;" OwnerUserId="8533" LastEditorUserId="755" LastEditDate="2015-07-25T18:16:13.527" LastActivityDate="2015-07-25T18:51:34.697" Title="What is the authority in the UK?" Tags="&lt;easa&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17229" PostTypeId="2" ParentId="17228" CreationDate="2015-07-25T16:10:34.007" Score="4" Body="&lt;p&gt;EASA: this is a European Union body, so yes, the UK is a member state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAA: There are many Civil Aviation Authorities worldwide, basically each is a national entity within the corresponding state. So, specifically for the UK, yes, there exists a body known as CAA that is a state entity, formally independent but in practice dependent on the UK Government (Dept. of Transport). Their web page is: &lt;a href=&quot;http://www.caa.co.uk/&quot; rel=&quot;nofollow&quot;&gt;http://www.caa.co.uk/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the complex configuration of EU law, both EASA and the UK CAA can have their word to say on operations within UK territory. Though, as CAA say themselves:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The CAA works closely with the European Aviation Safety Agency (EASA) to promote the highest common standards of safety and environmental protection in civil aviation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="8558" LastEditDate="2015-07-25T18:51:34.697" LastActivityDate="2015-07-25T18:51:34.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17230" PostTypeId="1" AcceptedAnswerId="17244" CreationDate="2015-07-25T17:11:11.770" Score="2" ViewCount="612" Body="&lt;p&gt;Has anyone performed a &lt;a href=&quot;https://en.wikipedia.org/wiki/Lomcovak&quot; rel=&quot;nofollow&quot;&gt;Lomcovak manoeuvre&lt;/a&gt; in a C152 aerobat, is it even possible, or would that likely overstress the engine?&lt;/p&gt;&#xA;" OwnerUserId="9519" LastEditorUserId="19" LastEditDate="2016-07-08T11:46:41.800" LastActivityDate="2018-08-09T22:45:24.903" Title="Is it possible to perform the Lomcovak manoeuvre in a C152 aerobat?" Tags="&lt;aerobatics&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17231" PostTypeId="1" CreationDate="2015-07-25T17:20:50.563" Score="5" ViewCount="1176" Body="&lt;p&gt;In the world of private jets, say a G-450, at a fixed throttle setting, does it simply go faster the higher it climbs/flies? &lt;/p&gt;&#xA;" OwnerUserId="9524" LastEditorUserId="19" LastEditDate="2016-07-08T11:47:36.910" LastActivityDate="2016-07-08T11:47:36.910" Title="What is the relation between airspeed and altitude at fixed throttle setting in a private jet?" Tags="&lt;airspeed&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17233" PostTypeId="2" ParentId="15529" CreationDate="2015-07-25T18:25:37.777" Score="0" Body="&lt;p&gt;I believe those of us that found DTC to be the best of the three will be disappointed in the other two.  I miss DTC already.  Lockheed Martin, to me, is as primitive as the Flight Service tools I used for 13 years as a briefer for the FAA. CSC is not much better.  Recently CSC e-mailed me and said they were not interested in any of my negative comments about their system. (They were suggestions).  If there is a commercial briefing system I can afford I would consider it over these two!  If we could follow the money trails from lobbist and not allow non-aviation oriented quota hires to make decisions in the FAA DTC would have easily won over the other two!  I fly only VFR these years, Bonanza, and rarely at night.  I rarely fly to new places and have routes I have flown for years. DTC made briefings to and from these easy to obtain, read and understand.  I was very happy with DTC.&lt;/p&gt;&#xA;" OwnerUserId="9526" LastActivityDate="2015-07-25T18:25:37.777" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17234" PostTypeId="1" AcceptedAnswerId="17238" CreationDate="2015-07-25T19:57:36.590" Score="13" ViewCount="10772" Body="&lt;p&gt;How are the 4-digit squawk codes assigned to individual flights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/17218/5517&quot;&gt;This answer&lt;/a&gt; indicates that there should be a &quot;correct&quot; one. How does ATC know what is &quot;correct&quot; and what is &quot;incorrect&quot;?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2020-01-26T12:38:26.457" Title="How are squawk codes assigned?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17235" PostTypeId="2" ParentId="17221" CreationDate="2015-07-25T20:08:08.507" Score="6" Body="&lt;p&gt;You want clean, undisturbed air flowing over the control surfaces. You could probably squeeze it in someplace above or below the engines, but it would not be easy without negatively influencing the aerodynamics over the elevators. As you can see from the diagram, you would need to get them pretty far out of the way of the engine cowlings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you place either engines or elevators low down along the fuselage they suffer from the disturbed air coming of the wing; this is not desirable. As it stands, the side engines (#1, #3) are already &lt;a href=&quot;https://aviation.stackexchange.com/questions/1543/why-do-dc-9-and-md-82-have-engines-that-are-slightly-angled-upwards&quot;&gt;angled for the downwash&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the more need for a sturdier rudder, this is partially weighed against that you have a longer moment arm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Mfsti.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Mfsti.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://www.state.gov/cms_images/tu154m_vl_russia2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;state.gov&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-07-18T12:23:53.167" LastActivityDate="2019-07-18T12:23:53.167" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17237" PostTypeId="2" ParentId="17221" CreationDate="2015-07-25T21:12:05.867" Score="10" Body="&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/1400/how-do-conventional-and-t-tails-differ/2947#2947&quot;&gt;T-tail&lt;/a&gt; is not so bad. Its main advantages are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A smaller vertical tail is required, because the horizontal tail acts like an endplate and enhances the efficiency of the vertical tail.&lt;/li&gt;&#xA;&lt;li&gt;When the vertical tail is swept, a T-tail will allow to make the horizontal tail smaller as well, because it gains additional lever arm in this configuration.&lt;/li&gt;&#xA;&lt;li&gt;By designing the junction with the vertical well, the T-tail has less interference drag. It also helps to reduce wave drag, especially when using a well designed Küchemann body (the round, long, spiky thing on the tail junction of a Tu-154) by stretching the structure lengthwise.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As soon as the cruise Mach number demanded tail sweep, the T-tail became the preferred solution. Placing the engines at the rear fuselage put them higher, so &lt;a href=&quot;https://en.wikipedia.org/wiki/Foreign_object_damage&quot; rel=&quot;noreferrer&quot;&gt;FOD&lt;/a&gt; became less of a worry, and the wing could be kept clean for maximum lift resulting in shorter runway requirements. In the days before &lt;a href=&quot;https://en.wikipedia.org/wiki/Computational_fluid_dynamics&quot; rel=&quot;noreferrer&quot;&gt;CFD&lt;/a&gt;, it was much easier to get the wing right when no pylons with barrels at their ends were sticking from it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine is mounted near the place where normally the horizontal tail would be, it is much easier to relocate the horizontal to the top of the vertical than trying to join both together. The mass of the engines will require a relatively rearward wing position, so the lever arm of a conventional tail would be rather small. By shifting it up to the top of the swept vertical tail, its lever arm is much larger, making the T-tail especially attractive for configurations with rear-mounted jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second reason is better failure tolerance. Note that the T-tail designs are from the early jet age. Their first flight years were: &lt;a href=&quot;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&quot; rel=&quot;noreferrer&quot;&gt;Caravelle&lt;/a&gt; 1955, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_JetStar&quot; rel=&quot;noreferrer&quot;&gt;Jet Star&lt;/a&gt; 1957 (both not real T-tails, I know, and having little tail sweep), &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Trident&quot; rel=&quot;noreferrer&quot;&gt;Trident&lt;/a&gt; 1962, &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_VC10&quot; rel=&quot;noreferrer&quot;&gt;VC-10&lt;/a&gt; 1962, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-62&quot; rel=&quot;noreferrer&quot;&gt;Ilyushin 62&lt;/a&gt; 1963, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727&quot; rel=&quot;noreferrer&quot;&gt;Boeing 727&lt;/a&gt; 1963, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-134&quot; rel=&quot;noreferrer&quot;&gt;Tu-134&lt;/a&gt; 1963, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-141_Starlifter&quot; rel=&quot;noreferrer&quot;&gt;C-141&lt;/a&gt; 1963, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hamburger_Flugzeugbau_HFB-320_Hansa_Jet&quot; rel=&quot;noreferrer&quot;&gt;Hansa Jet&lt;/a&gt; 1964, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-154&quot; rel=&quot;noreferrer&quot;&gt;Tu-154&lt;/a&gt; 1968. The designers were afraid an engine failure would also damage the horizontal tail and would turn a survivable accident into a lethal disaster.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-08-15T06:42:30.533" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17238" PostTypeId="2" ParentId="17234" CreationDate="2015-07-25T21:34:38.710" Score="12" Body="&lt;p&gt;To start out with, I'll be referring to how the US does it, and it's generally laid out in the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/JO%207110.66D%20.pdf&quot;&gt;National Beacon Code Allocation Plan&lt;/a&gt;. Every facility has various blocks of codes that they can use to assign to flight plans, as described in the linked document. For example, a smaller tower/approach control, could use the codes 0101-0177 for IFR flights that are only in their airspace, and 0201-0277 for the VFR flights that stay in their airspace, and a Center would have a similar bank of codes for flights just in their airspace, and then a different bank for codes that go to different centers. The whole purpose to these allocations, is to minimize the need to change the squawk code while in the air, and to avoid overlap with adjacent facilities. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As flight plans are submitted to the various computers, about 30 min before an Instrument flight plan's proposed time, it's officially assigned a code from the available blocks, and it's printed at the departure airport or facility that'll first work it. Flight plans stay in the system, depending on however long the center sets. Often it's 2 hours, sometimes 3, but during bad whether when lots of flights are being delayed, it could be extended to 4+ hours. The drop interval helps to keep enough codes available for aircraft intending to depart, while allowing flight plans to go away if something happens and the flight won't be departing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft just randomly calls ATC, the controller types it in to either the radar or flight plan system, depending on what extent the pilot wants services, and then the system prints out an appropriate beacon code.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-07-25T21:34:38.710" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17240" PostTypeId="2" ParentId="17083" CreationDate="2015-07-26T01:05:10.660" Score="-4" Body="&lt;p&gt;&quot;Follow the black holes&quot; doesn't sound like a good thing. A &quot;black hole approach&quot; is an optical illusion during night approaches when there isn't any light between you and the approach array. You tend to and up flying too low and crash short of the runway. So, &quot;following the black hole&quot; sounds to me like ATC is telling you to believe the illusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Taxi not too deep&quot; sounds like alternate phraseology for &quot;land as short as possible and exit quickly&quot;. ATC will give this instruction when something bigger or faster is coming in behind you.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-26T01:05:10.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17241" PostTypeId="2" ParentId="17231" CreationDate="2015-07-26T02:06:35.850" Score="4" Body="&lt;p&gt;Simple answer: within normal operating altitudes, mostly yes, due to the thinner air causing less drag while the engines are producing approximately the same amount of thrust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other simple answer: it depends, and there will be an optimal altitude above which the aircraft travels slower due to the engines losing thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a lot of aspects that complicate it, but assuming you're basically asking 'at full throttle, does an aircraft travel faster at higher altitude?' the simple answer is yes, up to a point. Obviously that doesn't apply above the service ceiling, and the optimal altitude may be lower than this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The optimal altitude will be a function of the engine performance and airframe.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-07-26T02:06:35.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17242" PostTypeId="2" ParentId="17223" CreationDate="2015-07-26T02:14:33.557" Score="2" Body="&lt;p&gt;First up, commercial pilots (both major airlines and cargo airlines): It depends on the country and airline, but the retirement age for a pilot is generally 65 in most countries, and almost always somewhere between 55 (e.g. British Airways) and 65 (standard in much of the U.S.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no set last age at which you could be recruited, so in theory it's just before those ages, but in practice you're unlikely to be hired by a company if you can't work there for at least 5 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're not yet a qualified pilot, though, you'd have to account for this time too (no company is going to hire you and train you just in time to retire). In practice, therefore, the likely realistic age is at least 10 years prior to the retirement age for the country/company in question, and likely 15.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if we move into pure conjecture for a moment, I'd hazard that you'd find it quite hard to find a company willing to take on an untrained pilot much after their early-mid 40s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for a private pilot: As long as you can pass the medical you can fly and, indeed, learn to fly, at any age. There's no maximum age, although as you'd expect most (but certainly not all) people start to struggle with passing the medical sometime in their 70s. By 80, there aren't too many pilots still flying around.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2017-10-18T20:42:10.413" LastActivityDate="2017-10-18T20:42:10.413" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17243" PostTypeId="1" CreationDate="2015-07-26T04:20:42.443" Score="18" ViewCount="2897" Body="&lt;p&gt;Let's say Bob is flying at Mach 1 and then John, in another aircraft, overtakes him at Mach 3. They are flying parallel to each other, say 500 meters apart. And there is no wind. Their relative speed is Mach 2 of course. Does Bob hear a sonic boom from John, and why or why not?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please explain it sufficiently enough so that I can apply it to other situations. For example, would it still work if their speeds were more like Mach 1 and Mach 1.25?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="11215" LastEditDate="2018-11-17T21:35:39.040" LastActivityDate="2018-11-17T21:35:39.040" Title="Does a Mach 1 plane hear a sonic boom from a Mach 3 plane overtaking him?" Tags="&lt;supersonic&gt;&lt;noise&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="17244" PostTypeId="2" ParentId="17230" CreationDate="2015-07-26T04:48:45.157" Score="6" Body="&lt;p&gt;The list of approved maneuvers is in the POH, and I'm sure the Lomcovak is not listed. If you are willing to do unapproved maneuvers, the issue is that because the aircraft tumbles rather than flies in this maneuver you have a few things to worry about: it starts with an outside maneuver, it is inverted, and the exit requires a high-speed dive which will exceed Vne or the +6g the 152 Aerobat is rated for. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="39" LastEditDate="2015-07-26T22:23:30.447" LastActivityDate="2015-07-26T22:23:30.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17245" PostTypeId="2" ParentId="17231" CreationDate="2015-07-26T06:26:35.450" Score="9" Body="&lt;p&gt;The basic principles needed for an answer are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thrust varies linearly with air density.&lt;/li&gt;&#xA;&lt;li&gt;Lift at constant angle of attack (AoA) equally varies linearly with air density.&lt;/li&gt;&#xA;&lt;li&gt;Increasing the angle of attack from a low value will improve the lift to drag ratio (L/D), while increasing it from a higher value than the AoA at optimum L/D will decrease it.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft will settle at the point where speed equals drag and lift equals weight. If the altitude change improves L/D, the aircraft has excess thrust to fly faster.&lt;/li&gt;&#xA;&lt;li&gt;Due to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lapse_rate&quot; rel=&quot;nofollow&quot;&gt;atmospheric lapse rate&lt;/a&gt;, the speed of sound decreases with altitude.&lt;/li&gt;&#xA;&lt;li&gt;Above a certain Mach number ($M_{dd}$ = &lt;a href=&quot;https://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;nofollow&quot;&gt;drag divergence Mach number&lt;/a&gt;), drag increases nonlinearly over dynamic pressure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now the answer depends on where you start:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Low altitude, moderate throttle setting: The aircraft will speed up, because it was flying at a low AoA in dense air. Climbing brings it closer to the polar point of optimum L/D.&lt;/li&gt;&#xA;&lt;li&gt;Low altitude, high throttle setting: If the aircraft flew at close to its $M_{dd}$, climbing will put it in colder air where it needs to fly slower to maintain the same Mach number. Depending on the starting speed, the aircraft might slow down.&lt;/li&gt;&#xA;&lt;li&gt;High altitude, moderate throttle setting: Now the thrust decrease with altitude will dominate the equation, because the aircraft will fly close to its optimum polar point. Once it flies above the AoA of minimum drag, climbing will slow it down.&lt;/li&gt;&#xA;&lt;li&gt;High altitude, high throttle setting: If it flies above the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tropopause&quot; rel=&quot;nofollow&quot;&gt;tropopause&lt;/a&gt; and close to the polar point of minimum drag, the air temperature does not change with altitude, and climbing will not change flight speed. It will stay close to its $M_{dd}$. Once it flies above the polar point of minimum drag, however, climbing will again slow it down.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-27T08:12:49.330" LastActivityDate="2015-07-27T08:12:49.330" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17246" PostTypeId="1" AcceptedAnswerId="17632" CreationDate="2015-07-26T07:31:54.047" Score="7" ViewCount="368" Body="&lt;p&gt;Thought experiment: Suppose I am equipped with an ideal automobile which can reach speeds of 700mph.  On a highway, I can deftly maneuver around light traffic to achieve an average speed of 500mph.  A friend, standing on an overpass, dares me to pass under him at high speed at a precise moment in time some distance in the future giving me enough time to reach my destination (if perhaps a bit early or late).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would find this maddenly difficult.  Likewise, aren't timed flybys difficult?  How are they executed?  Given an F16 with an average pilot, how accurate could a stadium flyby be timed?  What technology is used?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:  Let be more specific.  I.  What are the exact procedures used by a flight team performing a timed stadium flyby.  II.  Given a highly trained team, what is the expected deviation from desired flyover team and actual flyover time?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I still don't think this question has been answered in detail.  Also, there must be some technique that dates from the pre-GPS era.  Even with GPS, I suspect (but I may be wrong) that the answer is more than staring at a GPS and intuiting the appropriate adjustment in speed.&lt;/p&gt;&#xA;" OwnerUserId="9532" LastEditorUserId="9532" LastEditDate="2015-08-06T17:08:36.237" LastActivityDate="2015-08-06T19:52:24.720" Title="How are timed flybys executed, and what are their accuracy?" Tags="&lt;flight-planning&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17247" PostTypeId="1" AcceptedAnswerId="17269" CreationDate="2015-07-26T09:04:04.617" Score="9" ViewCount="1073" Body="&lt;p&gt;Can someone expand a bit for the layman with emphasis on &lt;strong&gt;Intercept geometry&lt;/strong&gt; the following image depicting the envelope of a SA-2 missile against a moving Target.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jt1wt.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jt1wt.gif&quot; alt=&quot;Effects of Speed and Altitude on SA-2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="19" LastEditDate="2016-11-21T16:06:40.283" LastActivityDate="2016-11-21T16:06:40.283" Title="How can the concept of &quot;intercept geometry&quot; be explained in simple terms?" Tags="&lt;military&gt;&lt;missiles&gt;&lt;flight-interception&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17248" PostTypeId="1" AcceptedAnswerId="17250" CreationDate="2015-07-26T09:14:48.830" Score="4" ViewCount="1076" Body="&lt;p&gt;Assume the pilot is flying too fast and high for an emergency landing. What movement of the control surfaces must they apply to land the aircraft safely on the runway? I heard this type of manuever is also used in gliders and light aircraft&lt;/p&gt;&#xA;" OwnerUserId="7653" LastEditorUserId="39" LastEditDate="2015-07-27T02:10:50.893" LastActivityDate="2015-07-27T05:37:48.410" Title="How to reduce altitude in a passenger jet without gaining forward speed in an emergency?" Tags="&lt;landing&gt;&lt;commercial-aviation&gt;&lt;emergency&gt;&lt;ailerons&gt;&lt;rudder&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17250" PostTypeId="2" ParentId="17248" CreationDate="2015-07-26T10:09:28.543" Score="8" Body="&lt;p&gt;Ah that's a good question indeed. You asked &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How to reduce altitude in a &lt;strong&gt;passenger jet&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Normally most of the passenger jets have &lt;a href=&quot;https://en.wikipedia.org/wiki/Spoiler_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;spoilers&lt;/a&gt; They are effective and can be &lt;a href=&quot;https://aviation.stackexchange.com/a/1956/878&quot;&gt;deployed at any speed&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now what happens in case you don't have spoilers for any reason. I was discussing the subject with a pilot many years ago and he told me the trick you mentioned: you apply rudder to one direction (I assume opposite to the engine rotation to avoid unpleasant surprises). That increases dramatically the forward surface of the plane against the relative air flow. That results in increased drag and thus speed loss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But yaw causes roll (and vice versa). Also the wing of the side you are yawing to, has less lift because it is shaded from the forebody of the plane. This is where the aileron is needed. You need aileron to maintain lateral stability and prevent the aircraft from rolling. See the image bellow. The orange lines denote the area of increased drag by the fuselage. The green area is the &quot;shaded&quot; area of decreased lift of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mtaLb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mtaLb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Top view from &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/b/bc/B737Familyv1.0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia&lt;/a&gt;. Derivative work by me.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to that pilot, this is more effective than spoilers. But there is a trap: You need to be careful not to yaw the plane too much because the shaded wing will loose too much of its lift and will result in capsizing the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; Finally, you mentioned emergency. There are different types of emergencies. Pressurization is an emergency situation but does not affect aircraft control (at least not directly). Hydraulics problems or engine loss is an emergency as well. But that will affect the way you will handle the aircraft. Here I cannot help you. A trained pilot perhaps can answer, though I believe that the answers will vary depending on each planes flight manual.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-26T14:52:53.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17251" PostTypeId="2" ParentId="17248" CreationDate="2015-07-26T10:14:50.543" Score="6" Body="&lt;p&gt;In addition to the standard aerodynamic controls - ailerons, rudder, elevator - many large aircraft also have a spoiler (also known as speed brake). This has the effect of adding drag without adding lift - in fact in some designs it will reduce lift. This allows a swift descent to be made without increasing airspeed. Gliders also have spoilers, as they only have one shot at a landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the absence of a spoiler (or in addition to it) an aircraft can dump lift without increasing airspeed by carrying out a manouevre called a &quot;forward slip&quot;. The ailerons are applied in one direction and the rudder in the opposite direction, meaning that the aircraft is actually moving at an angle to the direction the nose is pointing (see the answer by Stelios for a nice diagram). This adds drag and disrupts the aerodynamics of the wings.  This was among the manouevres used in successfully landing the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow&quot;&gt;Gimli Glider&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In either case, just as in regular flight, forward speed and vertical speed can be manipulated together by using the elevator: lowering the nose increases both airspeed and descent rate.&lt;/p&gt;&#xA;" OwnerUserId="4162" LastEditorUserId="4162" LastEditDate="2015-07-27T05:37:48.410" LastActivityDate="2015-07-27T05:37:48.410" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17252" PostTypeId="2" ParentId="17243" CreationDate="2015-07-26T11:24:49.127" Score="5" Body="&lt;p&gt;Both planes would create a sonic boom.  The boom is a pressure wave.  The pressure wave is not aware of the relative speed of the two planes.  The slower plane would hear the boom when then cone overtakes it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more curious question is will the faster plane actually hear the boom from the slower as it approaches.   I think the answer there there is the faster plane will hear the sonic boom of the slower when it crossed the cone - it just starts in the cone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Sonic_boom&quot; rel=&quot;nofollow&quot;&gt;Sonic_boom&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just have one year of freshman physics so don't take this as authoritative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I spoke with a fighter pilot (and instructor) and he said the trailing plane would feel the shock wave going in a out but not that big a deal.  Mainly the air pitot tube speed indicator would go off for a bit.  Since you are moving with the percussion it speeds out the force.  The individual cone when they meet would have minimal interaction as relative to each other they are subsonic.&lt;/p&gt;&#xA;" OwnerUserId="8649" LastEditorUserId="8649" LastEditDate="2015-08-05T23:22:25.873" LastActivityDate="2015-08-05T23:22:25.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17253" PostTypeId="1" CreationDate="2015-07-26T12:02:32.583" Score="7" ViewCount="1332" Body="&lt;p&gt;What advantage does the &lt;a href=&quot;https://en.wikipedia.org/wiki/Blisk&quot; rel=&quot;nofollow&quot;&gt;&quot;blisk&quot; or &quot;bladed disk&quot; type rotor&lt;/a&gt; have over the usual rotor system?&lt;/p&gt;&#xA;" OwnerUserId="9536" LastEditorUserId="1696" LastEditDate="2016-07-06T21:50:04.417" LastActivityDate="2017-08-07T17:29:15.413" Title="What is the advantage of the blisk design in the new Trent XWB engine?" Tags="&lt;engine&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17254" PostTypeId="2" ParentId="17253" CreationDate="2015-07-26T12:33:09.457" Score="7" Body="&lt;p&gt;Since the blades and rotor disc are a single piece, there are no additional fittings (bolts, screws etc) to attach the blades reducing complexity and weight.  The blade root joints are also a source of failure through manufacturing defects and fatigue cracks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disadvantage is that any damage to a blade requires the entire assembly to be replaced rather than a single blade.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-07-27T11:51:20.300" LastActivityDate="2015-07-27T11:51:20.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17255" PostTypeId="2" ParentId="17234" CreationDate="2015-07-26T13:26:24.293" Score="9" Body="&lt;p&gt;A squawk code (aka Mode A code) is used in Flight Data Processing systems to correlate a radar track (or other surveillance system track) to a flight plan. Basically the radar downlinks the squawk code from the aircraft and the FDPS looks up the associated flight plan. Usually there are a number of codes which do not link to a flight plan but are reserved for local purposes and VFR flights without a flight plan. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In Europe there are 3 Mode A code allocation systems in use:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Originating Region Code Assignment Method (ORCAM)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Under ORCAM aircraft are assigned a code on departure and will maintain this code until they fly into a region where their code conflicts with another flight. Then it is reassigned. For every region there are 'local' codes which are only used for regional / domestic flights, and there are 'transition' codes for region boundary crossing flights.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Centralised Code Assignment &amp;amp; Management System (CCAMS)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In CCAMS a computer system allocates codes to flights based on the planned trajectory through the CCAMS area and ensures there will never be a code conflict.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Elementary Surveillance (ELS)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When using ELS, if a flight needs to be (re-)assigned a mode A code and it is in Mode S radar coverage and the downlinked aircraft ID correlates with the filed flight ID on the flight plan, Mode A 1000 is assigned. Squawk 1000 serves as a signal to the Flight Data Processing System to correlate the radar track to the flight plan based on the downlinked Mode S aircraft ID instead of the Mode A code. This method is usually used in combination with ORCAM, sometimes with CCAMS. By using ELS, multiple aircraft fly with squawk 1000 which frees up other Mode A codes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/content/documents/nm/surveillance/surveillance-mode-s-acid-operational-concept-1-0-20111025.pdf&quot;&gt;Eurocontrol document (PDF)&lt;/a&gt; gives some more detail about the code allocation schemes in use. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;South America and the Caribean use the &lt;a href=&quot;http://www.icao.int/NACC/Documents/eDOCS/ATM/ORCAM%20CAR%20SAM%20-%20SSR%20Codes%20en.pdf&quot;&gt;ORCAM (PDF)&lt;/a&gt; system. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-07-26T13:26:24.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17256" PostTypeId="1" AcceptedAnswerId="17267" CreationDate="2015-07-26T13:37:14.413" Score="6" ViewCount="3451" Body="&lt;p&gt;Assume the left engine failed and the right engine is at full power. The pilot has pulled his nose up and turned towards left. Is it possible for him to land the plane on a runway to his left? The plane is an ATR-72 turboprop design&lt;/p&gt;&#xA;" OwnerUserId="7653" LastActivityDate="2015-07-27T06:11:47.573" Title="What would happen if one of the engines failed during takeoff and other engine is on full power?" Tags="&lt;commercial-aviation&gt;&lt;takeoff&gt;&lt;engine-failure&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17257" PostTypeId="1" AcceptedAnswerId="17261" CreationDate="2015-07-26T14:27:24.140" Score="8" ViewCount="13378" Body="&lt;p&gt;I installed an app some months ago, which gives a push message when an aircraft squawks &lt;code&gt;7700&lt;/code&gt;. The first time it happened, I thought the plane was about to crash, but fortunately nothing happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, within the last months, I got a lot of notifications, maybe a few a week or so. I'm wondering, why there are so many emergency alerts? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read about possible &lt;a href=&quot;https://aviation.stackexchange.com/questions/16792/is-there-a-list-of-aircraft-which-squawked-7700&quot;&gt;reasons&lt;/a&gt; for &lt;code&gt;7700&lt;/code&gt; squawks and they seem to be manifold. Isn't the purpose of an emergency call to be used only in really critical scenarios? How is an aircraft going down to be differentiated from one carrying a sick passenger? Are there any plans in the industry to change the current system?&lt;/p&gt;&#xA;" OwnerUserId="9537" LastEditorUserId="14957" LastEditDate="2016-10-02T12:32:44.417" LastActivityDate="2020-08-03T05:08:47.923" Title="Why are there so many 7700 squawks?" Tags="&lt;emergency&gt;&lt;transponder&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17258" PostTypeId="2" ParentId="17257" CreationDate="2015-07-26T14:45:06.310" Score="6" Body="&lt;p&gt;The reason for squawking 7700 is that Air Traffic Control can easily identify you on the radar display. This eases identification and coordination between air traffic controllers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The differentiation between various scenarios is done by voice communication, there is no need to complicate the squawk system. Typically there is not more than one aircraft squawking 7700 at the same time in an airspace so the identification based on code 7700 is simple and effective. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-07-26T14:45:06.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17259" PostTypeId="2" ParentId="17256" CreationDate="2015-07-26T14:46:35.707" Score="-8" Body="&lt;p&gt;The PIC has the authority to do whatever he/she deems necessary to control the situation. Landing on another runway on the same airport is one of several choices. Not all airports have multiple runways, and if they do, not all are suitable for an immediate landing, but if the runway layout allows for it, then yes, landing on another runway is a viable option. But only one of many. I always impart in my ME students to consider landing on another runway in case of an engine failure upon take-off, IF (and only if) the runway layout is suitable for that. On most airports, landing on another runway is not an option.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastEditorUserId="9483" LastEditDate="2015-07-27T03:55:40.830" LastActivityDate="2015-07-27T03:55:40.830" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17260" PostTypeId="1" AcceptedAnswerId="17268" CreationDate="2015-07-26T14:51:39.543" Score="16" ViewCount="3851" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1955/when-can-spoilers-be-used-on-airliners/1956#1956&quot; title=&quot;This related question on Aviated SE describes how in many aircraft spoilers are deploy-able at any speed.&quot;&gt;This related question on Aviation SE describes how in most aircraft spoilers (flight spoiler mode not ground spoilers) are deploy-able at any speed&lt;/a&gt; But flaps on the other hand mostly have a V_FE above which they cannot be deployed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume the speed limit imposed on using flaps is due to structural reasons? I am just wondering why spoilers do not have a similar limit? Looking at a spoiler photo in the deployed position it looks like the spoiler mechanism ought to be under a lot more stress than the flaps. Am I wrong here? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or are spoilers reinforced to a degree out of need that is not felt necessary for flaps? i.e. There can be a legitimate need to deploy flight-spoilers at a speed higher than for flaps. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-27T06:26:25.587" Title="Do flaps have a maximum speed limit but spoilers don't? Why?" Tags="&lt;flaps&gt;&lt;spoilers&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17261" PostTypeId="2" ParentId="17257" CreationDate="2015-07-26T15:04:13.117" Score="10" Body="&lt;p&gt;7700 is a &quot;general emergency&quot; squawk. It tells ATC that there is &quot;a problem&quot; of some sort with a particular plane. And I agree that this &quot;general umbrella&quot; type of squawk is a good idea. I have several disagreements with the FAA, but this is a good one. Several thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the specific nature of the emergency is only for the PIC and ATC. Nobody else needs to be informed, they can't help anyway.&lt;/li&gt;&#xA;&lt;li&gt;oftentimes lost comm is part of the problem. So they can't talk, but you still want to show ATC that you have an emergency. You could squawk 7600 for lost comm, but if you have some truly serious, like an engine failure (I personally don't consider lost comm anything even remotely near &quot;truly serious&quot;), you can inform ATC with 7700 that you have a more serious problem than just lost comm. They'll notice the &quot;lost comm&quot; aspect of this situation on their own, by not being able to talk to you. Now they know you have something more serious, because you don't show 7600.&lt;/li&gt;&#xA;&lt;li&gt;If you really want to use different squawk codes for different types of emergencies, it would merely add to the already large amount of numbers and codes pilots and controllers have to learn by heart. In an emergency where time might be of the essence, trying to remember abstract information like this can be difficult.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&quot;The first time it happened, I thought the plane was about to crash&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why did you think that? 7700 is not some &quot;we're gonna die&quot; type of squawk. It's a general &quot;umbrella type&quot; of squawk for all sorts of emergencies. An intelligent pilot will squawk 7700 for any &quot;small&quot; or &quot;big&quot; type of emergency (and who is supposed to be the judge on &quot;big&quot; vs. &quot;small&quot;?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;How is an aircraft going down to be differentiated from one carrying a sick passenger?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It isn't, because it doesn't matter. The people that are familiar with the situation (PIC and ATC) are in communication, unless lost comm, in which case the controller who can't glean more info from the 7700 squawk can't help anyway, and nobody else needs to be informed because they can't help anyway. Squawk codes aren't meant for desktop people like you who download some app and watch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Would you recommend handling this issue differently than it is done now, if you were in the position to?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No. There are good reasons to have an &quot;umbrella&quot; type of squawk for all types of emergencies.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastEditorUserId="14957" LastEditDate="2016-10-02T12:29:23.400" LastActivityDate="2016-10-02T12:29:23.400" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="17262" PostTypeId="2" ParentId="17234" CreationDate="2015-07-26T15:10:57.140" Score="2" Body="&lt;p&gt;In the US, the codes follow section 5 of the 7110.65. Non-discrete codes end in 00 and can cover multiple aircraft. Discrete codes never end in 0 and are specific to one aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;How does ATC know what is &quot;correct&quot; and what is &quot;incorrect&quot;?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The computer system generates them. There are certain &quot;slot ranges&quot; for every facility. It's not that the controller punches in something he came up with on his own. He &lt;em&gt;requests&lt;/em&gt; a squawk from the system, and then the computer spits out one, and that's the one he/she tells the pilot over the radio. To answer your question on how it knows correct vs incorrect, I'd have to say that this is implemented correctly in the software that runs the backend.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-26T15:10:57.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17263" PostTypeId="1" CreationDate="2015-07-26T15:20:55.487" Score="9" ViewCount="923" Body="&lt;p&gt;FAR § 61.56.(c).(1) states that every two years I must have&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Accomplished a flight review given in an aircraft for which that pilot is &lt;em&gt;rated&lt;/em&gt; by an authorized instructor.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer to my question hinges on the exact meaning of the word &quot;rated&quot;. If I've been signed off to solo in a C-172, am I &quot;rated&quot; for that aircraft as far as this regulation is concerned? &lt;/p&gt;&#xA;" OwnerUserId="7601" LastEditorUserId="39" LastEditDate="2015-07-28T05:42:26.677" LastActivityDate="2019-02-07T07:02:25.313" Title="I hold both a Sport Pilot License and a Student Pilot certificate. Can I do my BFR in a C-172?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;&lt;light-sport-aircraft&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17264" PostTypeId="2" ParentId="17260" CreationDate="2015-07-26T15:26:09.237" Score="17" Body="&lt;p&gt;Spoilers are used to shed energy when the aircraft is too fast or too high. That means they need to be used when the aircraft is flying fast and are designed accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand flaps are used to increase lift and when flying fast, there is plenty of lift, so there is no point in using flaps at high speed and therefore they are not designed for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally flaps on large aircraft are more complicated mechanically. Spoilers only rotate around their forward edge, but flaps on large aircraft &lt;em&gt;extend to the rear&lt;/em&gt; in addition to rotating downward.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-07-26T16:08:55.183" LastActivityDate="2015-07-26T16:08:55.183" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17265" PostTypeId="2" ParentId="17243" CreationDate="2015-07-26T15:43:31.763" Score="4" Body="&lt;p&gt;This should be asked in the physics part of stack exchange, but here are some thought about sonic boom:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To answer your question, you must be clear about frame of reference (this is one reason why you should ask your question in physics.SE)&lt;/li&gt;&#xA;&lt;li&gt;A sonic boom is created because an aircraft is going faster than the speed of sound. This speed is measured &lt;strong&gt;relative to the airmass&lt;/strong&gt; the aircraft is flying in.&lt;/li&gt;&#xA;&lt;li&gt;A sonic boom is heard only in a specific place &lt;strong&gt;relative to the supersonic aircraft&lt;/strong&gt;. The boom is due to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Shock_wave&quot; rel=&quot;nofollow&quot;&gt;shock wave&lt;/a&gt; genereted by the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;In the case you ask for, if any traveller cross the shock wave of the slower supersonic aircraft (whatever the direction), he can hear a sonic boom. This sentence is true as long as you consider a supersonic aircraft (either the slower or the faster)&lt;/li&gt;&#xA;&lt;li&gt;Any sound is less strong when you are far away from the source of this sound. This include shock wave (and that's why you won't hear a supersonic aircraft flying few thousands of miles away from you)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2015-07-26T15:43:31.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17266" PostTypeId="1" AcceptedAnswerId="17274" CreationDate="2015-07-26T16:38:17.397" Score="20" ViewCount="26062" Body="&lt;p&gt;The temperature of the gaseous products exiting from the nozzle is higher than the melting point of the nozzle material. So how do the nozzles survive without melting despite exposure to such temperatures? What is the feature which enables them to do so?&lt;/p&gt;&#xA;" OwnerUserId="7653" LastActivityDate="2015-07-27T14:53:12.830" Title="How are rocket engine nozzles able to survive very high temperatures without melting?" Tags="&lt;aerospace-materials&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17267" PostTypeId="2" ParentId="17256" CreationDate="2015-07-26T16:43:36.560" Score="13" Body="&lt;p&gt;No, no, by all means &lt;em&gt;don't&lt;/em&gt; turn left. See also &lt;a href=&quot;https://aviation.stackexchange.com/questions/8118/why-should-you-not-turn-in-the-direction-of-an-inoperative-engine&quot;&gt;Why should you not turn in the direction of an inoperative engine?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transport category aircraft are capable of climbing out on one engine. It is a certification requirement for them. So if the left engine failed after rotation, the first thing the pilot has to concentrate on is to keep the plane flying and under control. That means ease the pull on the stick a bit to avoid stalling as the plane is not able to climb as fast and push the right rudder pedal to keep the plane flying straight¹.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the plane is in straight climb at $V_2$ speed, it's time to deal with the engine. First both pilots cross-check the instruments and the rudder position to determine it was the left engine that failed. Then they feather the propeller (auto-feather &lt;em&gt;might&lt;/em&gt; have done it already) and cut fuel to the failed engine. If the engine fire warning is on and did not extinguish when fuel was cut, they discharge fire extinguisher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These things are done according to standard emergency procedure that the pilots have to remember and train in simulator. I don't know the specifics for ATR-72, but in all aircraft it is roughly like above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile the aircraft climbs to safe altitude and then they should level off and let it accelerate a bit to get some safety margin for manoeuvring. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane is now in relatively safe condition. Even if engine was on fire, it is unlikely to spread while the aircraft is flying. So the pilots now have time to declare emergency and ask the controller for what options they have for landing. Whether they do a complete circuit and land back on the same runway or turn around and land in opposite direction or land on some other runway then depends on wind and where they are relative to the runways at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were many accidents where plane crashed after one engine failure during take-off because pilots started manoeuvring before they attained sufficient altitude and safe speed. It is better not to hurry, engine failure does not require it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Of course provided there are no obstacles in the way. For example if you were taking off from VQPR runway 33 and your right engine quit, you'd still have to do a right turn rather early to avoid the &lt;a href=&quot;https://s3.amazonaws.com/uploads.uservoice.com/assets/056/648/233/original/VQ_AD_2_VQPR_6-1_en.pdf?AWSAccessKeyId=14D6VH0N6B73PJ6VE382&amp;amp;Expires=1498306973&amp;amp;Signature=Vy3axlPfGnzruXewRPz8BwLB%2Bqk%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mr. Smith's house&lt;/a&gt; right in the axis of the runway and quite a bit above it. But for any airport that require such avoidance (and there is quite a few of them in various mountains), the pilots are specifically briefed and trained for that airport which includes instructions on how to best handle engine failure during take-off and during approach and viability of the procedure is verified in simulator and with a test flight. The above answer just outlines the generic procedure.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-27T06:11:47.573" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17268" PostTypeId="2" ParentId="17260" CreationDate="2015-07-26T16:45:32.097" Score="16" Body="&lt;p&gt;Spoilers reduce lift potential when deployed and increase drag. This makes them doubly helpful at high speed: Not only will the aircraft slow down, but the pilot has less of a chance to break something important when they are deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrast this with flaps: They create only a moderate drag increase, but vastly increase the potential lift. If they would be deployed at high speed, the pilot (or an unexpected gust) could easily overstress not only the flap structure, but also the whole wing. Extending them at high speed is suicidal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, some regulations demand that spoilers must be useable even beyond the maximum speed. For gliders, where the spoilers are called airbrakes, &lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/CS-22_Amendment%201%20revised.pdf&quot;&gt;JAR part 22&lt;/a&gt; says in AMC 22.143:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Compliance with 22.143(a) should include the extension of airbrakes at&#xA;  speeds up to 1.05 VNE. The time to extend airbrakes should not exceed&#xA;  2 seconds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For airliners the regulations are more lenient, and the manufacturer is free to limit their use as he sees fit. However, it is good practice to allow spoiler extension over the full speed range.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-07-27T06:26:25.587" LastActivityDate="2015-07-27T06:26:25.587" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17269" PostTypeId="2" ParentId="17247" CreationDate="2015-07-26T17:20:37.623" Score="11" Body="&lt;p&gt;Intercept geometry is the bubble of space in which the &lt;a href=&quot;https://en.wikipedia.org/wiki/S-75_Dvina&quot;&gt;SA-2 missile&lt;/a&gt; can be effective against a specific aircraft. Crucial here is the detection range of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fan_Song&quot;&gt;radar system guiding the missile&lt;/a&gt;, given here as 40 nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the speed of the target, the missile has only a limited time to ascend to the altitude of the target and to close in. The combination of speed and altitude of the SR-71 (&lt;a href=&quot;http://www.wolframalpha.com/input/?i=Mach%203.2%20in%2080000%20ft&quot;&gt;1854 kt&lt;/a&gt;), moving at more than 30 nm per minute, will leave only a very small intercept geometry, and it has to overfly the missile launcher almost directly to be vulnerable. Once the target flies above 90.000 ft and Mach 3.5 (or employs effective countermeasures), it will be unassailable by the SA-2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrast that with the fate of an aircraft flying only Mach 1 at 60.000 ft (which equals &lt;a href=&quot;http://www.wolframalpha.com/input/?i=Mach%201%20in%2060000%20ft&quot;&gt;573.6 kt&lt;/a&gt;): Moving at less than 10 nm per minute, its course can go past the launcher with a 25 nm offset, but it will still be in range of the Fan Song - SA-2 combination. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-07-26T17:20:37.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17270" PostTypeId="2" ParentId="17266" CreationDate="2015-07-26T18:25:36.973" Score="3" Body="&lt;p&gt;In some cases the fuel itself will be cycled through tubes in the nozzle to keep the nozzle within a defined operating temperature range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's the case with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rocketdyne_F-1#Design&quot; rel=&quot;nofollow&quot;&gt;Rocketdyne F-1&lt;/a&gt;, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just noticed a comment referring to this practice. The F-1 is the actually the engine that was used on the Saturn V.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-07-26T18:25:36.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17271" PostTypeId="2" ParentId="17253" CreationDate="2015-07-26T18:27:57.100" Score="5" Body="&lt;p&gt;&quot;Module weight savings of 15% and improved aerodynamic efficiency&quot;, &lt;a href=&quot;http://www.rolls-royce.com/customers/civil-aerospace/products/civil-large-engines/trent-xwb/technology.aspx#technology&quot; rel=&quot;nofollow&quot;&gt;according to Rolls Royce&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a manufacturing point of view, replacing literally hundreds of sub-components (individual blades, etc) with a single part has obvious advantages - though of itself, that wouldn't give the customer any benefit if it didn't also reduce weight and/or improve performance.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastEditorUserId="1696" LastEditDate="2016-07-06T21:50:45.307" LastActivityDate="2016-07-06T21:50:45.307" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17272" PostTypeId="1" CreationDate="2015-07-26T18:47:43.190" Score="11" ViewCount="1444" Body="&lt;p&gt;The FAA’s &lt;a href=&quot;https://www.faa.gov/licenses_certificates/airmen_certification/interactive_airmen_inquiry/&quot; rel=&quot;noreferrer&quot;&gt;Search Airmen Certificate Information&lt;/a&gt; reads in part&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Personal Information&lt;/strong&gt;&lt;br /&gt;&#xA;We do not display your SSN, certificate number, or date of birth. We will display a releasable address in accordance with the &lt;a href=&quot;https://www.faa.gov/licenses_certificates/airmen_certification/MEDIA/106_SEC_715.PDF&quot; rel=&quot;noreferrer&quot;&gt;Aviation Investment and Reform Act for the 21st Century&lt;/a&gt; (PDF). We display medical information based on FAA’s &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/&quot; rel=&quot;noreferrer&quot;&gt;Civil Aerospace Medical Institute&lt;/a&gt; (CAMI) medical records. If the medical dates are incorrect, please contact CAMI at (405) 954-4821.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/licenses_certificates/airmen_certification/airmen_faq/&quot; rel=&quot;noreferrer&quot;&gt;Airmen Certification Frequently Asked Questions&lt;/a&gt; contains the same intended exclusions.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Do you display my certificate number on the Internet?&lt;/strong&gt;&lt;br /&gt;&#xA;We do not display your SSN, certificate number, or date of birth on the FAA website.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The U.S. Department of Transportation publishes an &lt;a href=&quot;https://cms.dot.gov/individuals/privacy/pia-airmenaircraft-registry-modernization-system#PII&quot; rel=&quot;noreferrer&quot;&gt;FAA Privacy Impact Assessment – Airmen/Aircraft Registry Modernization System (RMS)&lt;/a&gt; notes that Social Security Numbers were used in the past for certificate numbers, but policy has changed.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Personally Identifiable Information (PII) and RMS&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;To handle airmen certifications and aircraft registrations, FAA requires PII about airmen and aircraft owners/registrants. With this in mind, RMS may include or collect the following data on airmen and/or aircraft owners and registrants, either for authentication or certification requirements: Name, Date of birth (airmen only), Social security number (airmen only), Driver’s license number, passport number, or government ID number, Physical Description (height, weight, hair and eye color, sex, and citizenship), Address (airmen only), Medical records (airmen only), Certificate number (airmen only). In the past, RMS used an airman’s social security number as the certificate number. FAA is now changing that practice, developing unique certificate numbers not affiliated with social security number. During this change, airmen can request, online or offline, that his or her social security number not appear as a certificate number. For an individual’s PII to be included in RMS, that individual must be associated with an airmen or aircraft certificate or application.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is clear that for airmen whose certificate numbers match their SSNs, adhering to best practices and remaining clear of practices to avoid (&lt;em&gt;cf.&lt;/em&gt; &lt;a href=&quot;https://www.socialsecurity.gov/phila/ProtectingSSNs.htm&quot; rel=&quot;noreferrer&quot;&gt;recommendations from the Social Security Administration&lt;/a&gt;) are wise courses of action, primarily to reduce the risk of identity theft and fraud.&lt;/p&gt;&#xA;&lt;p&gt;To get credit for &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_catalog.aspx&quot; rel=&quot;noreferrer&quot;&gt;FAA WINGS training&lt;/a&gt; hosted at &lt;a href=&quot;http://www.aopa.org/Education/Online-Courses.aspx&quot; rel=&quot;noreferrer&quot;&gt;AOPA’s Air Safety Institute&lt;/a&gt;, certificate number is a required field—but also one whose value ASI is careful to note that they do not store and that they pass with some level of encryption protection.&lt;/p&gt;&#xA;&lt;p&gt;So many legal disclaimers raise red flags. What are the risks of disclosing an FAA airman certificate number? Is all the handwringing due strictly to the fact that some certificate numbers are also Social Security Numbers and nothing else? How should I protect my certificate number, which differs from my SSN?&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sub&gt;Note: All quoted passages were retrieved from the linked resources on July 26, 2015.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-29T20:15:26.307" Title="How should I safeguard my FAA certificate number?" Tags="&lt;usa&gt;&lt;faa&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17273" PostTypeId="2" ParentId="17243" CreationDate="2015-07-26T19:58:32.210" Score="23" Body="&lt;h2&gt;To answer the question:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Yes, and even more, both would be able to notice the sonic boom of the other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To understand why, you have to understand how sonic booms are created. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sound is nothing more than waves of different air pressure travelling through the air. Once released by an aircraft or other object, they start to propagate in all directions with the speed of sound &lt;em&gt;in the resting air&lt;/em&gt;. (This means the waves do not travel faster than sound, even when the aircraft does!) If we mark e.g. the regions of high pressure, we get growing circles, the center of each being the point where it was created by the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is moving, the circles will not be concentric, like in this animation for an object traveling at half the speed of sound:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vg1V7.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vg1V7.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is moving with the speed of sound, the circles start to touch each other on a line perpendicular to the track of the aircraft, just where the aircraft is. This is not so clear on the next animation, as there are simply not (big) enough circles.&lt;br&gt;&#xA;However, on this line, all the regions of high pressure sum up to a region of 'very high' pressure. This is the shock wave, which is often referred to as sound barrier. (The term also describes just the insurmountable speed limit encountered by non-supersonic aircraft.) If this shock wave passes an observer on the ground, he will hear a sonic boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BjfoP.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BjfoP.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft accelerates more, the shock wave isn't perpendicular any more, instead, you get two lines. In reality (3D), you get a cone with the aircraft at the tip, and the opening angle is defined by the speed of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2f4lK.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2f4lK.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to answer your question: As the tip of the cone is where the aircraft is, this cone travels with the aircraft, and with its speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if an aircraft is overtaken by a supersonic aircraft, it will be overtaken by the cone-shaped shock wave of that aircraft a little bit later, too. Also, the faster aircraft will pass the shock wave of the slower aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Remarks&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An aircraft itself is very loud, but also dampens every noise from outside, and headsets and helmets may contribute to the dampening, too. So, I don't know if a pilot would hear something from the boom. Maybe he does not, but the aircraft definitely crosses the shock wave.&lt;/li&gt;&#xA;&lt;li&gt;My explanation does not describe where the sound comes from. While the sound of a subsonic aircraft mostly comes from the engines, it comes from the compression of air at the surfaces of supersonic aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;s&gt;This cone sometimes is visible, as on the following picture of an F18, stolen from &lt;a href=&quot;http://air-attack.com/images/single/551/An-FA-18C-Hornet-Breaks-the-Sound-Barrier.html&quot; rel=&quot;noreferrer&quot;&gt;air-attack.com&lt;/a&gt;. This is because the high pressure region is followed by a low pressure region, where air expands and moisture may condensate. The picture also shows that there are usually two shock waves, each where the cross section of the aircraft changes significantly.  One is generated near the canopy and one near the wings.&lt;/s&gt; &lt;strong&gt;EDIT:&lt;/strong&gt; As commented by @PeterKämpf, this picture does NOT show an F18 at &lt;em&gt;supersonic&lt;/em&gt; speed. It is at &lt;em&gt;transsonic&lt;/em&gt; speed, which is close to, but still below mach 1. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9724/how-are-condensation-cones-created-by-supersonic-airplanes&quot;&gt;The fog forms due to other effects.&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sOTlm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sOTlm.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, here is an other picture of a Northrop T-38 at mach 1.1, showing the shock waves, from &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Schlieren_photograph_of_T-38_shock_waves.jpg&quot; rel=&quot;noreferrer&quot;&gt;wiki commons&lt;/a&gt;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/RtedN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RtedN.jpg&quot; alt=&quot;foo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-07-28T07:50:01.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17274" PostTypeId="2" ParentId="17266" CreationDate="2015-07-26T21:05:10.037" Score="20" Body="&lt;p&gt;There is actually quite a lot of information on the subject in the Braeunig web site &lt;a href=&quot;http://www.braeunig.us/space/propuls.htm&quot;&gt;Basics of Space Flight&lt;/a&gt;. To give the salient points:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Liquid-fueled rocket engines&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the nozzle &lt;em&gt;and&lt;/em&gt; the combustion chamber itself need to be cooled. Although most of the thermal energy produced is ejected with the exhaust, some of it will indeed push hardware temperatures up if not checked. Techniques include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Regenerative cooling, where the propergols (both propergols, or just the fuel) are pumped through a jacket around the nozzle before going into the combustion chamber. This cools down the nozzle, and heats up the propergols that may be cryogenic in nature. This is what was used in the Saturn Vs' Rocketdyne F-1 engines, and the Space Shuttle main engines.&lt;/li&gt;&#xA;&lt;li&gt;Dump cooling, similar to the above but the fuel used to cool the nozzle is dumped overboard instead of being fed into the combustion chamber and being used as, well, fuel.&lt;/li&gt;&#xA;&lt;li&gt;Film and transpirative cooling, where a thin film of coolant or fuel is created near the chamber wall.&lt;/li&gt;&#xA;&lt;li&gt;Ablative cooling, where part of the combustion chamber or nozzle wall is sacrificed. As the material is melted or otherwise burned away, it absorbs some of the thermal energy, thus saving whatever is behind it.&lt;/li&gt;&#xA;&lt;li&gt;Radiation cooling, where nozzle design is such that heat has time to be evacuated through the part's exterior wall. This is used mainly in small engines, not main.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Solid-fueled rocket engines&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No information available. Nothing. Zilch. Nada. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would seem that the nozzle and combustion chamber materials just need to be strong enough to withstand the heat from the burning gasses. It is perhaps worthwhile to note that solid rocket engines are designed to burn just one single time, and for a relatively short period of time (even the Space Shuttle boosters were extensively overhauled before being put back into service, with any necessary parts changed). Rocket engines need to withstand working conditions for just minutes, instead of the thousands of hours an A/C jet engine turbine would be expected to work without failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also be reasonable to assume -though this is strictly something I am making up on the go, with much hand waving- that of the techniques described above for liquid-fueled rocket engines, at least two could be easily adapted to solid engines:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Film cooling, with an extra tank of cooling liquid on board.&lt;/li&gt;&#xA;&lt;li&gt;Ablative cooling, with some refractive material used to coat the inner surface of the nozzle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8558" LastActivityDate="2015-07-26T21:05:10.037" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17275" PostTypeId="2" ParentId="17256" CreationDate="2015-07-26T23:07:06.390" Score="5" Body="&lt;p&gt;The aircraft is able to fly on one engine. Sudden manoeuvring immediately after an engine failure on take-off is not advisable; the margin from the minimum control speed with one engine out (V&lt;sub&gt;mc&lt;/sub&gt;) is low and assumes a 5 degree bank into the working engine. The abnormal operating procedures of the ATR-72 advise the crew that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The conduct of any emergency procedures or the analysis of any&#xA;  technical problems should not normally take place until:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a.  The vertical and lateral flight path is under positive control;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. &#xA;  Possible ground contact is no longer a threat; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. Altitude is&#xA;  above 400 FT (AGL)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When the above conditions are met the engine shutdown procedure should be followed. These actions are to be memorized by the crew instead of being read from a check list as they are critical. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the engine is shutdown the crew can assess the situation and decide on further actions. Returning to the departure airport will be the normal course of action but if circumstance dictate so the pilot in command may decide to land on an alternative airport. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Following an engine shutdown a two engine aircraft should normally proceed to the nearest suitable airport, although there is no objection to the aircraft proceeding to the destination provided the increased flying time is not significant.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;The quotes are from an ATR-72 SOP book I found on &lt;a href=&quot;http://www.scribd.com/doc/61827537/SOP-ATR72#scribd&quot; rel=&quot;nofollow&quot;&gt;scribd&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-07-27T00:47:24.720" LastActivityDate="2015-07-27T00:47:24.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17276" PostTypeId="1" CreationDate="2015-07-27T01:10:42.593" Score="4" ViewCount="1583" Body="&lt;p&gt;In an aerodynamic stall, which flight control surface (limited to ailerons, elevators and rudder) remains effective for the longest period of time during the stalling condition? In other words, which of the three loses its effectiveness &lt;em&gt;last&lt;/em&gt;?&lt;/p&gt;&#xA;" OwnerUserId="9541" LastEditorUserId="62" LastEditDate="2015-07-27T13:35:41.600" LastActivityDate="2015-07-27T15:59:00.783" Title="Stalls: which flight control surface is effective last?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17277" PostTypeId="2" ParentId="17276" CreationDate="2015-07-27T02:44:29.717" Score="3" Body="&lt;p&gt;It depends on the type of stall and the loading configuration of the aircraft. The short answer is that the rudder typically stalls last because the angle of attack of the wings is independent of the AOA of the vertical stabilizer. However it's usually among the least effective control surfaces in getting out of a straight dive (very useful for recovering from spins and spiral dives though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of the horizontal surfaces, it depends on which one has a higher AOA at the time the wings stall, which is dependent on how the plane entered the stall, and how the aircraft is configured. A sudden pitch-up in an airframe with an aft CG will cause the horizontal stabilizers and thus the elevators to depart first. In most other situations especially when the CG is forward of the CL, the wings will have the higher AOA as the nose pitches downward, so the elevators will remain useful &lt;em&gt;as long as&lt;/em&gt; the tail isn't caught in the turbulent airflow off the wing. T-tails have this disadvantage; the higher tail location normally puts the tail in cleaner air, but in a stall the turbulent air off the wing shelters the tail making it less effective.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-27T15:59:00.783" LastActivityDate="2015-07-27T15:59:00.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17278" PostTypeId="2" ParentId="17266" CreationDate="2015-07-27T03:04:37.967" Score="1" Body="&lt;p&gt;I remember watching this video from &lt;strong&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=Gf406v6WB3A&quot; rel=&quot;nofollow&quot;&gt;Youtube&lt;/a&gt;&lt;/strong&gt; that provide most of the science and technologies needed to build a space shutter. And it also explained how to nozzle survive from the heat generated by the rocket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it passes the fuel to the engine through small pipes at the outer layer of the nozzles whereby the fuel is very cold. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the fuel is cold, the heat from flame of the rocket will be absorb by the fuel's pipe and avoiding direct heat contact with the nozzle (Which I assume this is what they called Thermal Equilibrium?). Hence avoiding the heat to melt the nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answer by @ALAN WARD are far more accurate than mine, but I think the video can provide easier understanding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cheers.&lt;/p&gt;&#xA;" OwnerUserId="9542" LastActivityDate="2015-07-27T03:04:37.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17279" PostTypeId="1" AcceptedAnswerId="17285" CreationDate="2015-07-27T03:23:14.567" Score="4" ViewCount="686" Body="&lt;p&gt;Various regulatory authorities around the world have framed strict rules prohibiting entry of passengers into cockpit. It makes some sense to not allow anyone into the cockpit (learning from 9/11), while you are flying but when on ground, what is the harm in allowing someone to enter the cockpit? The passengers are frisked thoroughly before being allowed to board the aircraft, and if you are on the ground then there is a lot of security around. So, what are the factors behind not allowing outsiders into cockpit, while on ground?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://timesofindia.indiatimes.com/india/Visitors-in-cockpit-four-pilots-lose-licence/articleshow/33199583.cms&quot;&gt;Visitors in cockpit, four pilots lose licence&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-07-27T14:12:28.120" Title="Why won't you allow someone into the cockpit while on ground?" Tags="&lt;safety&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17280" PostTypeId="1" CreationDate="2015-07-27T03:37:46.813" Score="4" ViewCount="1216" Body="&lt;p&gt;Reading about composite materials in the 787 on &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#Design&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, I came across this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Carbon fiber, unlike metal, does not visibly show cracks and fatigue, prompting concerns about the safety risks of widespread use of the material; the rival Airbus A350 uses &lt;strong&gt;composite panels on a frame&lt;/strong&gt;, a more conventional approach, which its contractors regarded as less risky.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I bolded the curious part. What does &quot;composite panels on a frame&quot; mean exactly?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2015-07-27T08:33:00.577" Title="What does &quot;composite panels on a frame&quot; mean?" Tags="&lt;airbus&gt;&lt;boeing&gt;&lt;aerospace-materials&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17281" PostTypeId="2" ParentId="17280" CreationDate="2015-07-27T06:43:40.920" Score="2" Body="&lt;p&gt;Composite material are built in panels. The idea is to built a metal structure (spars and ribs for example), and to cover it with composite sheets, instead than aluminium. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not to do a structure in composite? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Composite materials are very complex and still not completely known: we have been using Aluminium in the last century and we know EVERYTHING about it, also very unusual or peculiar behavior. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Composites are still to be completely understood, that's one of the reason to use a metal structure. Moreover composites are not suitable for isotropic stress and they will never completely replace the metal. &lt;/p&gt;&#xA;" OwnerUserId="637" LastActivityDate="2015-07-27T06:43:40.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17282" PostTypeId="1" AcceptedAnswerId="17283" CreationDate="2015-07-27T07:53:23.110" Score="12" ViewCount="1210" Body="&lt;p&gt;If I understand correctly, heading is usually measure relative to the pole (either magnetic or true). Traveling at a constant heading can't be approximated as travelling straight ahead when near the pole. The extreme case being heading to 180° and crossing the south pole.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Althought there are not many aircraft in this situation as explained in &lt;a href=&quot;https://aviation.stackexchange.com/questions/11449/no-aircraft-crosses-directly-over-the-pole-why&quot;&gt;this question&lt;/a&gt;, using the heading may not be relevant. &#xA;How is the navigation handled is such area? Is the heading used?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-27T15:37:49.503" Title="Is the heading used near the pole?" Tags="&lt;navigation&gt;&lt;heading&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17283" PostTypeId="2" ParentId="17282" CreationDate="2015-07-27T08:32:19.980" Score="12" Body="&lt;p&gt;Near the poles 'polar grid navigation' is used. By placing a rectangular grid over the pole, aligned with the prime meridian, a local coordinate system is created. Aircraft fly constant grid courses near the poles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your example crossing the south pole approaching over the prime meridian the true course will change from 180° (T) to 000° (T), but the grid course will remain 180° (G) all the time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Grid courses and true courses can be converted easily, this &lt;a href=&quot;https://www.youtube.com/watch?v=_ulnjZTMpEk&quot; rel=&quot;nofollow&quot;&gt;youtube video&lt;/a&gt; explains it nicely (although he gets the grid track in the wrong direction in the end, it should be 110°(G) instead of 290°(G)) &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-07-27T15:37:49.503" LastActivityDate="2015-07-27T15:37:49.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17284" PostTypeId="2" ParentId="17280" CreationDate="2015-07-27T08:33:00.577" Score="3" Body="&lt;p&gt;Traditionally, aircraft are built of frames (analogous to a person's skeleton), as shown below, and the smooth outer skin of the aircraft consists of panels fixed to these frames.  There are many frames and, for example, the small size of the windows is because they have to fit between the frames.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bdl8G.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bdl8G.jpg&quot; alt=&quot;Boeing 747 frames&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Image source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Airframe#/media/File:Shuttle_Carrier_Aircraft_interior_bulkhead.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A350 uses this traditional construction, except the frames and panels are built of composite materials (carbon fibre reinforced plastic), rather than aluminium. However, the fuselage of the Boeing 787 seems to consist of a composite &quot;tube&quot;, with reinforcing ribs running the length of the plane. There seem to be many fewer &quot;ribs&quot; running around the fuselage in this design than in traditional ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YomnO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YomnO.jpg&quot; alt=&quot;Boeing 787 fuselage section&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner#/media/File:787fuselage.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-07-27T08:33:00.577" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17285" PostTypeId="2" ParentId="17279" CreationDate="2015-07-27T10:00:27.393" Score="4" Body="&lt;p&gt;I don't agree with the strict enforcement of this rule by the DGCA (but I'm not an airline pilot so I think my opinion doesn't really count on this matter). But there is logic behind the ban - many safety-critical actions are completed before the plane has left the gate. Such actions include calculating takeoff speeds, briefing the departure procedures, and completing various checklists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having people in the cockpit could prove to be a big distraction when trying to complete these tasks, particularly when the time is limited anyway such as on a short turnaround. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making a mistake before leaving the gate can definitely end in disaster. Take &lt;a href=&quot;https://en.wikipedia.org/wiki/Emirates_Flight_407&quot; rel=&quot;nofollow&quot;&gt;Emirates flight 407&lt;/a&gt; in 2009. The crew entered an incorrect takeoff weight into the system. As a result there wasn't enough thrust to rotate and the A340 barely cleared the airport fence. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="5517" LastEditDate="2015-07-27T14:12:28.120" LastActivityDate="2015-07-27T14:12:28.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17286" PostTypeId="1" AcceptedAnswerId="17306" CreationDate="2015-07-27T10:14:23.353" Score="24" ViewCount="51055" Body="&lt;p&gt;I heard this word so many time in military documentary about jets, especially fighter jets, but I don't fully understand what it is or how it works. In a documentary from the Discovery Channel, all but one fighter needed to engage afterburner to reach supersonic speed. Could you tell me why is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The documentary also states that a fighter jet rarely engages this system. If the afterburner system can make a jet fly faster, why don't they use it all the time? Is that because of the airframe cannot handle supersonic airflow for a long period of time?&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="1696" LastEditDate="2018-04-17T15:24:06.477" LastActivityDate="2020-11-20T22:11:32.930" Title="What is an afterburner and how long can a jet fly on afterburner?" Tags="&lt;jet-engine&gt;&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;afterburner&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17287" PostTypeId="2" ParentId="17286" CreationDate="2015-07-27T11:36:19.070" Score="17" Body="&lt;p&gt;By using the afterburner, fuel is injected into the downstream of the turbine. Exit velocity gets higher -&gt; More thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparison of the generated thrust in an F/A-18C Hornet:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum thrust &lt;strong&gt;without&lt;/strong&gt; afterburner   &lt;strong&gt;10,440 daN&lt;/strong&gt; (each 5'220 daN)&lt;/li&gt;&#xA;&lt;li&gt;Maximum thrust &lt;strong&gt;with&lt;/strong&gt; afterburner  &lt;strong&gt;15,660 daN&lt;/strong&gt; (each 7'830 daN)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(The F/A-18C Hornet uses 2 General Electric F404-GE-402 turbofans)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airplanes need the afterburner to reach supersonic speed because the &quot;normal&quot; use of the jet turbine doesn't generate enough thrust. Using the turbine in &quot;normal&quot; mode (without afterburner) is also called &quot;military power&quot; or &quot;dry&quot;. Using the turbine with afterburner is also called &quot;full power&quot; or &quot;wet&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Afterburner&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; wikipedia article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Due to their high fuel consumption, afterburners are usually used as little as possible; a notable exception is the Pratt &amp;amp; Whitney J58 engine used in the SR-71 Blackbird. Afterburners are generally used only when it is important to have as much thrust as possible. This includes during takeoffs from short runways, assisting catapult launches from aircraft carriers and during air combat situations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's true that a fighter jet rarely engage the afterburner because it uses extreme amounts of fuel. Sometimes up to the factor 10 to the normal fuel useage. Thats also why they don't use it all the time: The operating-range of the fighter-jet is drastically reduced by using the afterburner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot can use the afterburner in different stages to find the perfect ratio of fuel usage / speed / range..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source (In english): &lt;a href=&quot;http://www.lw.admin.ch/internet/luftwaffe/en/home/dokumentation/assets/aircraft/fa18.html&quot; rel=&quot;nofollow&quot;&gt;http://www.lw.admin.ch/internet/luftwaffe/en/home/dokumentation/assets/aircraft/fa18.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="9544" LastEditDate="2015-08-27T13:53:20.070" LastActivityDate="2015-08-27T13:53:20.070" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17288" PostTypeId="2" ParentId="17246" CreationDate="2015-07-27T12:30:12.850" Score="2" Body="&lt;p&gt;A friend of mine did ATC for &lt;a href=&quot;http://www.atterburymuscatatuck.in.ng.mil/&quot; rel=&quot;nofollow&quot;&gt;Camp Atterbury&lt;/a&gt; in Indiana. He used to coordinate the fly-by for the &lt;a href=&quot;http://www.indianapolismotorspeedway.com/events/indy500&quot; rel=&quot;nofollow&quot;&gt;Indianapolis 500&lt;/a&gt;. I believe the fly-by would be timed for the end of the &lt;em&gt;National Anthem&lt;/em&gt; (though, this being Indiana, it might have been at the end of &lt;em&gt;Back Home Again in Indiana&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They, of course, had an official schedule and knew when the song should finish. However, variations were always possible, and were expected. He was stationed at the track listening to the song, and had a radio to communicate with the pilots of whatever was flying by. They would know when they &lt;em&gt;should&lt;/em&gt; be on target, but he would give them a more accurate count-down to ensure they arrived as close to the end of the song as possible.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-07-27T12:30:12.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17289" PostTypeId="1" AcceptedAnswerId="17368" CreationDate="2015-07-27T12:44:30.600" Score="19" ViewCount="1860" Body="&lt;p&gt;An afterburner uses a lot more fuel for a little more thrust (rule of thumb: 50% more thrust for 5 times the fuel flow with full dry power). Is a flight maneuver possible where using the afterburner will result in less fuel use than flying the same maneuver with dry thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be precise: I am looking for a situation where the aircraft transits from state A to a desired state B. The transition is possible with both dry and wet thrust. Please describe a pair of A and B where less fuel is used in the transition when the afterburner is lit!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1696" LastEditDate="2018-04-16T15:24:57.153" LastActivityDate="2018-04-16T15:24:57.153" Title="When does the use of afterburners save fuel?" Tags="&lt;jet-engine&gt;&lt;fighter&gt;&lt;jet&gt;&lt;maneuver&gt;&lt;theory&gt;" AnswerCount="2" CommentCount="12" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17290" PostTypeId="1" CreationDate="2015-07-27T12:44:42.130" Score="0" ViewCount="3202" Body="&lt;p&gt;Blended wings have more efficiency than today's wing design,high lift to drag ratio,more efficiency,less fuel rate ,it have lot of advantages so why not they used for commercial airplanes as well as military aircraft rather than UAV.&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="5703" LastEditDate="2015-07-27T12:54:06.490" LastActivityDate="2015-07-27T13:27:54.787" Title="what is the disadvantage of blended wing body ,that they not used to achieve more than subsonic speed?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;military&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-07-27T13:34:14.933" ContentLicense="CC BY-SA 3.0" />
  <row Id="17291" PostTypeId="1" CreationDate="2015-07-27T13:00:15.897" Score="8" ViewCount="54018" Body="&lt;p&gt;When we talk about aircraft having a stable configuration, it refers to lateral, longitudinal and directional stability. Can someone give a practical explanation of what those are and how they work?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="62" LastEditDate="2015-07-27T15:12:28.183" LastActivityDate="2018-03-09T11:32:50.527" Title="What are lateral, longitudinal and directional stability?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="5" ClosedDate="2015-07-27T19:18:49.130" ContentLicense="CC BY-SA 3.0" />
  <row Id="17292" PostTypeId="2" ParentId="17290" CreationDate="2015-07-27T13:27:54.787" Score="0" Body="&lt;p&gt;One of the few production designs that approaches a blended-wing-body was &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow&quot;&gt;Lockheed Sr-71&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Lockheed_SR-71_Blackbird.jpg/300px-Lockheed_SR-71_Blackbird.jpg&quot; alt=&quot;Sr-71]&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surprise, with maximum Mach 3.2 it is also the fastest production aircraft ever built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because blended-wing-body does &lt;em&gt;not&lt;/em&gt; have better L/D at low speed. But generating part of lift with the body has some advantage for high-speed aircraft as it allows smaller wings that is better for high speed (and worse for low-speed).&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-27T13:27:54.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17294" PostTypeId="1" AcceptedAnswerId="17296" CreationDate="2015-07-27T13:35:45.683" Score="7" ViewCount="3916" Body="&lt;p&gt;Apart from the cost angle, which seems to be the biggest factor in airlines, is it technically possible to bring cabin atmosphere (includes pressure, temperature, humidity) etc. at par with ground level, at the cruising altitude of most airliners (say 35000 ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just want to understand what stops airliners from providing this kind of comfort to the passengers. I am assuming there might be issues of hull integrity in order to maintain higher cabin pressure etc.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-07-27T14:49:50.093" LastActivityDate="2019-08-27T16:04:00.960" Title="Can an airliner provide ground level cabin pressure, temperature, humidity etc?" Tags="&lt;cabin-pressure&gt;&lt;cabin-design&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17295" PostTypeId="2" ParentId="17294" CreationDate="2015-07-27T13:50:12.553" Score="5" Body="&lt;p&gt;Weight and strength.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At 10700 metres (35000 feet), the ambient pressure is about 24.8 KPA (3.6 PSI). &lt;/li&gt;&#xA;&lt;li&gt;The pressure inside the aircraft is about 75.8 KPA (11 PSI), assuming 8000 feet cabin altitude.&lt;/li&gt;&#xA;&lt;li&gt;Imagine a cabin door approximately 2 metres by 1 metre (18 square feet).&lt;/li&gt;&#xA;&lt;li&gt;The force on the door is about 3970 KGs (8750 pounds or 4.3 tons). &lt;/li&gt;&#xA;&lt;li&gt;Imagine now that the cabin is pressurised to 100 KPA (14.5 PSI).&lt;/li&gt;&#xA;&lt;li&gt;The force on the door is now 5830 KGs (12850 pounds or 6.4 tons)!&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And that's just one door.  Now imagine the extra force for all of the other doors, the windows and the fuselage itself.  The additional force would be huge.  To build a fuselage that strong would be very heavy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature can be controlled no matter what the cabin altitude and most people can cruise at 8,000 feet with no significant health effects.  Therefore, it is just not necessary, or cost effective, to build an aircraft strong enough to fly with a cabin altitude of zero.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-07-27T14:57:34.737" LastActivityDate="2015-07-27T14:57:34.737" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17296" PostTypeId="2" ParentId="17294" CreationDate="2015-07-27T14:02:40.690" Score="13" Body="&lt;p&gt;I'll touch on the humidity a bit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is actually a big issue for planes; they tried to make it a bit better on the Dreamliner and were able to bump it up a bit &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Humidity is improved, yet still dry as the desert. Humidity levels on the Dreamliner are 10%-15% — better than 7% on other planes on long trips&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://blogs.wsj.com/middleseat/2012/02/16/787-dreamliner-improvement-is-more-incremental-than-revolution-in-flying/&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;but it's still a big issue. There are two main reasons they can't really increase it that much. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off, water is very heavy. Since planes pump in dry exterior air they would have to humidify it which means they need to carry enough water to do so. This weight would greatly affect the useful load of the plane. Now you could try to recycle some of the ambient moisture, but on a large scale that takes power, which takes fuel, which comes back to the weight issue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other issue (although not as often thought about) is the longevity of the airframe. The extremely dry conditions that airliners see for most of their time actually helps to prevent corrosion on the airframe as well as rust on any rustable parts. By pumping moisture into the airframe you will run the risk of it causing real damage to the metal components. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature is a simple energy problem. To keep a plane hot you need to heat it faster than the exterior temp is cooling it (or evenly to keep it a constant temp). Insulation can help with this but you are still going to see some cooling. On a rudimentary level you can apply &lt;a href=&quot;https://en.wikipedia.org/wiki/Newton%27s_law_of_cooling&quot; rel=&quot;nofollow&quot;&gt;Newton's law of cooling here&lt;/a&gt; and keep in mind the &lt;a href=&quot;https://aviationweather.gov/products/nws/boston&quot; rel=&quot;nofollow&quot;&gt;exterior temperature&lt;/a&gt; is in the -40 (and below) area (according to today's charts).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On to the pressure, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This, of course, is a big one, but, in reality, it's not a big deal. While it may seem a bit irritating, 8000ft atmosphere equivalent is still more than breathable. The FAA does not &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Pilot-and-Passenger-Physiology/Oxygen-Use-in-Aviation.aspx&quot; rel=&quot;nofollow&quot;&gt;require continuous O&lt;sub&gt;2&lt;/sub&gt;&lt;/a&gt; until 14,000 ft for unpressurized planes, so an 8000 ft equivalent cabin is more than fine. Now from a comfort standpoint, your ears may pop and you may feel some discomfort, but it's more than safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a purely technological standpoint we can do this, but from an engineering use case standpoint it's better to sacrifice some of the pressure to build a lighter, thinner plane. This saves on fuel and material costs down the line. There is great hope that carbon fiber may bring a change to all this and 8000 ft equivalency will be a thing of the past. Boeing has been pushing this with the 787 having only a &lt;a href=&quot;http://www.ausbt.com.au/why-business-travellers-will-love-the-boeing-787-dreamliner&quot; rel=&quot;nofollow&quot;&gt;6000ft pressure level&lt;/a&gt; which they claim alleviates problems. I have not yet flown one so I don't know first hand how much better it really is. Then again I fly unpressurized stuff often and have become somewhat acclimated to it.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-28T13:20:35.623" LastActivityDate="2015-07-28T13:20:35.623" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17297" PostTypeId="2" ParentId="17276" CreationDate="2015-07-27T14:37:46.870" Score="1" Body="&lt;h2&gt;Standard configuaration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In a stall, the first part to show large-scale &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;separation&lt;/a&gt; is the inner wing. This is intentional - all control surfaces should stay operational as long as possible. When the angle of attack is increased further, the separation extends outward and affects the ailerons first. The elevator flies in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;downwash&lt;/a&gt; of the wing and sees less of an angle of attack change, even in an aircraft of marginal stability. With positive static stability, the lift coefficient of the horizontal tail is lower than that of the wing, increasing its stall margin further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pitch-up is violent enough to even stall the horizontal tail (which happens regularly in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/3484/how-is-a-wing-designed-to-be-stall-or-spin-proof&quot;&gt;spin&lt;/a&gt;), the rudder will still see attached flow, albeit at a strong &quot;sideslip&quot; angle. But it will still be attached in the symmetric flow of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8022/what-is-a-deep-stall-and-how-can-pilots-recover-from-it/8027#8027&quot;&gt;deep stall&lt;/a&gt;. In a spin, it might also separate if the rate of rotation is high enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the sequence for separation in a stall is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ailerons&lt;/li&gt;&#xA;&lt;li&gt;Elevator&lt;/li&gt;&#xA;&lt;li&gt;Rudder&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Canard configuration&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In a canard, things are reversed between wing and elevator, and the forward wing and its elevators will stall first. This way, the aircraft will pitch down automatically. Here the sequence is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Elevator&lt;/li&gt;&#xA;&lt;li&gt;Ailerons &lt;/li&gt;&#xA;&lt;li&gt;Rudder&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;During recovery, the sequence is reversed: The control surface which has attached flow last will also be the first to show re-attached flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that separation means that &lt;a href=&quot;https://aviation.stackexchange.com/questions/14209/why-is-a-control-surface-that-allows-two-sides-of-airflow-better-than-those-that&quot;&gt;only one side of the control surface&lt;/a&gt; shows separated flow - the opposite side is still working and provides the pilot with a limited controllability. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-27T14:37:46.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17298" PostTypeId="1" AcceptedAnswerId="17299" CreationDate="2015-07-27T14:38:47.817" Score="8" ViewCount="6328" Body="&lt;p&gt;In this video of a more &lt;a href=&quot;https://aviation.stackexchange.com/questions/2873/why-are-the-cockpit-controls-of-airplanes-so-complicated&quot;&gt;complex&lt;/a&gt; cockpit, belonging to the SR-71, why don't we see any windshields? Were they not required for the SR-71, or are they not captured in this video? If windshields were actually not there, then please elaborate why!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mEDB2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mEDB2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=tj9UwKQKE3A&quot; rel=&quot;nofollow noreferrer&quot;&gt;Video&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-07T14:42:02.257" Title="Did the SR-71 have any windshields?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;&lt;windows&gt;&lt;sr-71&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17299" PostTypeId="2" ParentId="17298" CreationDate="2015-07-27T14:42:22.050" Score="22" Body="&lt;p&gt;There are forward-facing windows in the SR-71. The image you posted is just of the instrument panel. The windows are better visible in the photo below. This is from a simulator but gives a better idea of what the cockpit looks like when in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The windows and cockpit are small due to the high speeds and altitudes that the plane is designed for, making the cockpit resemble a smaller fighter plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VDhiG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VDhiG.jpg&quot; alt=&quot;SR-71 Cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a side note, there are planes without windshields, a notable example being the &lt;a href=&quot;https://en.wikipedia.org/wiki/Spirit_of_St._Louis&quot; rel=&quot;noreferrer&quot;&gt;Spirit of St. Louis&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-07-27T14:42:22.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17300" PostTypeId="2" ParentId="17298" CreationDate="2015-07-27T14:48:13.530" Score="24" Body="&lt;p&gt;It did!&#xA;You can see a bit of it here &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ixt7h.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ixt7h.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or in the reflection here &#xA;&lt;a href=&quot;https://i.stack.imgur.com/H2NeL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H2NeL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And here it is from the exterior&#xA;&lt;a href=&quot;https://i.stack.imgur.com/oadYg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oadYg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-27T14:48:13.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17301" PostTypeId="2" ParentId="17266" CreationDate="2015-07-27T14:53:12.830" Score="5" Body="&lt;h3&gt;Solid rockets&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The environment of a solid rocket nozzle is indeed &lt;em&gt;very&lt;/em&gt; harsh.  In 1975 Nasa published SP-8115 specifically about solid rocket motor nozzles:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...design values a designer might encounter: throat diameters from about 1/2 inch to nearly 90 inches, motor pressures from under 400 pounds per square inch to 2000 pounds per square inch, expansion ratios from less than 4 to over 50, firing durations from less than one second to 200 seconds, thrust from a few hundred pounds to over 5 million pounds, flame temperatures from 5100° F to over 6000° F, and a wide variety of propellant compositions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While advances have been made in material and propellant sciences, this serves to illustrate the difficulty in designing rocket nozzles to withstand these pressures and temperatures without melting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the time nozzles were made out of a single piece of molded polycrystalline graphite, supported by metal housing structures.  They eroded (ablative) but were low cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tungsten was used for a time, but it was heavy and often cracked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later advances led to high strength carbon fiber and carbon matrix, often referred to as &lt;a href=&quot;https://en.wikipedia.org/wiki/Reinforced_carbon%E2%80%93carbon&quot;&gt;a &quot;carbon-carbon&quot; material&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Carbon-Carbon&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Also called reinforced carbon-carbon, it is used today in a wide variety of industries, from the leading wing edges and nose cones of spacecraft and ICBMs, to formula one race car brake rotors. In some forms it is well over $100,000 per square foot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not only does it withstand high temperatures well, it can withstand thermal shock and has a low coefficient of thermal expansion.  This means a significantly reduced risk of cracking due to thermal stress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a brittle ceramic, though, with reduced impact resistance compared to some high temperature materials.  It was this material that broke on the Space Shuttle Columbia due to an insulation strike which ultimately led to the later shuttle destruction on re-entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a rocket nozzle, impact resistance is not an issue - thermal shock and temperature is, and so this material is ideal for this use.  Even so, it is still ablative, and is not considered re-usable.  Re-usable rockets, however, are almost always of the liquid variety for re-fueling purposes, and those nozzles are liquid cooled from the cryogenic fuel sources. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://articles.adsabs.harvard.edu//full/1975NASSP8115....../0000001.000.html&quot;&gt;Solid Rocket Motor Nozzles.  NASA SP-8115&lt;/a&gt;   &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0470080248&quot;&gt;Rocket Propulsion Elements&lt;/a&gt;&lt;br&gt;&#xA;By George P. Sutton, Oscar Biblarz&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2015-07-27T14:53:12.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17302" PostTypeId="1" AcceptedAnswerId="17304" CreationDate="2015-07-27T15:03:30.720" Score="7" ViewCount="3698" Body="&lt;p&gt;A &lt;a href=&quot;https://youtu.be/02ddnGzxNZs&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube footage&lt;/a&gt; of a KLM Boeing 777 landing at Schiphol airport in the Netherlands is certainly scary as the plane bumps and weaves and rolls from side to side. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9lLpF.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9lLpF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are pilots generally trained to handle such eventualities (or are such landings common in certain regions of the world?) or was everyone involved including the pilot taking a risk in this case without diverting the aircraft to a nearby safe location?&lt;/p&gt;&#xA;" OwnerUserId="6833" LastEditorUserId="487" LastEditDate="2015-07-27T18:10:15.540" LastActivityDate="2016-06-30T21:20:56.710" Title="Are pilots generally trained for crosswind landings?" Tags="&lt;landing&gt;&lt;flight-training&gt;&lt;crosswind&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17303" PostTypeId="2" ParentId="17302" CreationDate="2015-07-27T15:11:52.350" Score="-2" Body="&lt;p&gt;In steady winds, even when strong or very strong, there is no excuse for bumping around like crazy. You have the &quot;concept&quot; of a &quot;stabilized approach&quot;, and only turb is a valid reason to destroy a stabilized approach. In turb that's a different story, but then you still would have to explain why you even attempted the landing. If turb is too strong, it's a good reason to divert. The famous Lufthansa case made the media (and YouTube footage) several years ago where they even had a wing strike on the left side, when tons of other aircraft had cancelled. These two pilots pressed on, seemingly suffering from the eponymous get-home-itis, and you see the result. So ... even turb is not always a valid excuse, because diverting is a safer option (assuming you don't HAVE to land because of low fuel or similar -- but then you'd even have less excuses, because you shouldnt' fly into turb with low fuel, etc.).&lt;/p&gt;&#xA;" OwnerUserId="9483" LastActivityDate="2015-07-27T15:11:52.350" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="17304" PostTypeId="2" ParentId="17302" CreationDate="2015-07-27T15:25:32.357" Score="16" Body="&lt;p&gt;Of course &lt;strong&gt;yes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Crosswind_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Crosswind landings&lt;/a&gt;, like the one in the video you linked, are very common. In fact, landings with no wind or only headwind are rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several techniques pilots are taught during their extensive training to land aircraft when there is crosswind. The Wikipedia article I referenced above lists them. Since your question isn't about them, we won't discuss them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certainly, extreme weather situation are not very common. Some parts of the world experience extreme weather more than other areas. Diverting to other airports is not always an option and in some cases, once an airplane is on the approach, &lt;a href=&quot;https://aviation.stackexchange.com/q/8805/65&quot;&gt;going around becomes impossible&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-07-27T15:25:32.357" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17305" PostTypeId="2" ParentId="17302" CreationDate="2015-07-27T15:45:22.280" Score="4" Body="&lt;p&gt;The answers so far deal with commercial flying, from a recreational perspective pilots are only as well trained as the amount they practice. Commercial organizations generally train their pilots for crosswind landings in simulators, and they usually fly enough to get real crosswinds often enough to keep in practice. Private pilots are trained in crosswind techniques in initial training, keeping good crosswind abilities is up to the pilot once they pass their test. I personally practice crosswind take-offs and landings as often as I can, however I know many pilots who won't fly if there's more than 5 knots across the runway.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-07-27T15:45:22.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17306" PostTypeId="2" ParentId="17286" CreationDate="2015-07-27T15:55:41.253" Score="40" Body="&lt;p&gt;An afterburner is a secondary combustion system which burns additional fuel downstream of the combustion chamber, to further increase thrust at the expense of much higher fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the Pratt &amp;amp; Whitney F100 afterburning turbofan, variants of which power the USAF's 4th-generation fleet of F-15s and F-16s:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wn32d.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wn32d.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final spoke-looking thing just beyond the turbine fins, plus all the space between the turbine core and the exhaust nozzle, is the afterburner. In this area, fuel is sprayed directly into the exhaust stream from the turbine core, where the heat from the air leaving the core is enough to ignite it. This additional pressure adds to the thrust produced by the turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I said, though, the tradeoff is increased fuel consumption, &lt;strike&gt;sometimes&lt;/strike&gt; usually dramatically so. The F-16 at full military power and low altitudes burns about 8000 pounds of fuel an hour, which with a full droptank configuration gives it about 2 hours' flight time. Cruising at higher altitudes, that flight time can be further extended as both the higher altitude and the lower throttle setting (about 80%) reduce fuel flow rate by up to 40% versus low-altitude flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In full afterburner at low altitudes, the F-16 can burn in excess of 64,000 pounds an hour. At full throttle, a U.S.-variant F-16 with maximum external fuel stores has about 20 minutes until it's on emergency reserves (which would only last an extra minute or so at full afterburner). The speed gain is minimal; the F-16 cruises at between 450-550 knots, while full afterburner only increases that to about 700-800 knots with a typical underwing loadout. So, burning 8 times the fuel, you get around a 50% speed boost.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-11-10T17:51:37.950" LastActivityDate="2015-11-10T17:51:37.950" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="17307" PostTypeId="2" ParentId="17291" CreationDate="2015-07-27T16:04:22.793" Score="2" Body="&lt;p&gt;Lateral stability is roll stability: the tendency of the aircraft to reduce its rolling and return to an upright position unless continually maintained in position by e.g. the ailerons. (This is &lt;a href=&quot;https://aviation.stackexchange.com/a/17021/4474&quot;&gt;usually only partial&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longitudinal stability is pitch stability: the tendency of the aircraft to reduce its pitching and return to a level position (relative to the direction it's traveling, at least) unless countered by e.g. the elevators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Directional stability (also known as vertical stability) is yaw stability: the tendency of the aircraft to reduce its yawing and return to a straight position (relative to the direction it's traveling, at least) unless countered by e.g. the rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All these are necessary to avoid having to continually make tiny, precise adjustments to all the controls. &lt;/p&gt;&#xA;" OwnerUserId="4474" LastEditorUserId="-1" LastEditDate="2018-03-09T11:32:50.527" LastActivityDate="2018-03-09T11:32:50.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17308" PostTypeId="2" ParentId="17286" CreationDate="2015-07-27T16:19:50.180" Score="13" Body="&lt;p&gt;It is possible to design an aircraft that can cruise at supersonic speeds without using afterburners (for example Concorde, the British TSR-2 strike/reconnaissance aircraft, and the Tu-144). The aerodynamic drag force is higher at transonic speeds than when supersonic, and using afterburners to accelerate through the transonic speed range qucker may actually reduce the total fuel burn. That was definitely the case for Concorde. The afterburners were also used to shorten the takeoff roll on Concorde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most jet fighters are not designed for &quot;efficient supersonic cruising in a straight line at constant speed,&quot; so supersonic flight without afterburners is not the main design consideration.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-07-27T16:19:50.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17309" PostTypeId="2" ParentId="17291" CreationDate="2015-07-27T16:25:32.060" Score="6" Body="&lt;p&gt;The answer here is found in the Pilot's Handbook of Aeronautical Knowledge (and probably elsewhere) and is as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/drV0P.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/drV0P.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longitudinal axis of an aircraft is more or less a straight line through the aircraft's nose cone or prop hub and the endpoint of the fuselage (the aircraft's center of gravity will usually lie along or just slightly above/below this line as well). It is the axis around which the aircraft rolls, controlled by the ailerons. The lateral axis is parallel to the wings and passes through the aircraft's center of gravity. It is the axis around which the aircraft pitches, as controlled by the elevators. Finally, the vertical axis is &quot;normal&quot; (perpendicular in all directions to) the geometric plane formed by the longitudinal and lateral axes, parallel to the aircraft's primary lift vector and (in level flight) its weight vector. It is the axis around which the aircraft yaws, controlled by the rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rotation about any one axis is the job of one linked set of control surfaces as mentioned above. Stability in that same axis, roughly defined as keeping that line passing through your aircraft pointing in the same direction, is the job of the other two surfaces in concert, but primarily the one that would move the endpoints of that axis up or down relative to the aircraft. So, elevators provide lateral rotation to achieve longitudinal stability, and vice versa for ailerons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It differs slightly for the vertical axis, as if your plane is both longitudinally and laterally stable, it's also &quot;vertically stable&quot;, however the plane is longitudinally and laterally stable, but completely out of control, in a &quot;flat spin&quot;. Stability in the vertical axis therefore is secondary to &quot;directional stability&quot;, which keeps the longitudinal axis pointing in a particular direction along the geometric plane formed by the lateral and longitudinal axes. In this case the rudder both controls yaw and provides directional stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to control surfaces, weight and especially the aircraft's center of gravity is important in stability. Ideally, most small planes are most stable in level flight when the CG of the aircraft is exactly on the centerline of the aircraft (between the tip of the nose and the tip of the tail) and slightly forward of the aircraft's center of lift (which depends on the wing's angle of attack but is usually close to the thickest point in the wing's cross-section). In this configuration, while the aircraft is travelling forward normally, downwash from the wings flow over the top of the horizontal stabilizer, keeping the nose level. In a stall, the slight nose-heavy configuration along with the stabilizers in the rear will cause the nose to point downward gently, restoring normal airflow and allowing the pilot to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the CG is too far forward, the pilot will need to apply upward pitch or trim to keep the nose level. This will reduce the amount of travel he will have available to pitch up, and in a stall, the plane will nose down sharply and the elevator may provide insufficient force for the pilot to pull out of the dive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the CG is too far aft, the plane will want to nose up constantly, and the pilot will have to apply downward elevator or trim. In a stall, a plane with an aft CG won't nose down, preventing the pilot being able to restore normal airflow over the wings. This is especially dangerous in an uncoordinated stall aka a spin; the aft center of gravity in combination with the forward thrust of the engine will &quot;stabilize&quot; the plane in the spin and make it impossible to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the CG is off the aircraft's centerline, the plane will tend to roll towards its heavier side. This is compensated for with ailerons or aileron trim, and for most everyday flight it's the easiest to compensate for, but it can cause unfamiliar roll behavior and a tendency to spiral down, which the pilot must be aware of and correct for.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-27T17:05:32.480" LastActivityDate="2015-07-27T17:05:32.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17310" PostTypeId="2" ParentId="17272" CreationDate="2015-07-27T16:31:36.157" Score="5" Body="&lt;p&gt;I guess the question is, what can someone do maliciously if they have your certificate number, and what's the risk of that happening?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My assumption is that they can do nothing - and therefore the risk is zero - because no one uses the number for anything: it isn't needed for medicals, training, TSA approvals, flight reviews, checkrides, renting aircraft, buying insurance etc. People do want to &lt;em&gt;see&lt;/em&gt; your certificate (and even take a copy) for various reasons, but no one will accept your certificate number &lt;em&gt;by itself&lt;/em&gt; as proof of anything. That's my experience in the part 91 GA world anyway; I have no idea if certificate numbers are more important for airline pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my guess - and it is a guess - is that this does indeed come from when SSNs were used as certificate numbers. And as a result, unless your certificate number is also your SSN, there's probably no reason to do anything special to try to protect it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-07-27T16:31:36.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17311" PostTypeId="2" ParentId="17302" CreationDate="2015-07-27T16:37:55.103" Score="12" Body="&lt;p&gt;In the US it is required &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dc2762bb93ba31239fc4904e73e17cf4&amp;amp;mc=true&amp;amp;node=se14.2.61_131&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;by law&lt;/a&gt; to be trained in cross wind landings.&lt;/p&gt;&#xA;&lt;p&gt;For large aircraft that require a type rating...&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§61.31   Type rating requirements, additional training, and authorization requirements...&lt;/p&gt;&#xA;&lt;p&gt;...(2) Received a logbook endorsement from an authorized instructor who has found the person proficient in the operation of the aircraft and its systems.&lt;/p&gt;&#xA;&lt;p&gt;(i) Normal and &lt;strong&gt;crosswind takeoffs and landings&lt;/strong&gt;;&lt;/p&gt;&#xA;&lt;p&gt;(ii) Wheel landings (unless the manufacturer has recommended against such landings); and&lt;/p&gt;&#xA;&lt;p&gt;(iii) Go-around procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;On a side note cross wind landings are very important since not all airports have 2 runway options. Some large commercial airports will have 2 crossing runways which will allow you to pick the best one for the days winds (they are usually built to the general prevailing winds in the area). This does not mean there will be no cross wind but it does allow you to mitigate it. Smaller airports may only have a single runway (or 2 parallel runways) which means you have no method of mitigation for the crosswind. There are even some big airports that are only single runway due to space  or geographic restrictions.&lt;/p&gt;&#xA;&lt;p&gt;It should also be noted that airplanes them selves have a &lt;a href=&quot;https://aviation.stackexchange.com/questions/201/what-is-a-demonstrated-crosswind-component&quot;&gt;demonstrated cross wind component&lt;/a&gt; to which they are tested to be safe to land in a cross wind of said velocity. This is not necessary a maximum (although it can be) but it is often used as such.&lt;/p&gt;&#xA;&lt;p&gt;As for how often this happens that is largely a factor of the airport and the local weather. For example I used to fly out of &lt;a href=&quot;http://www.airnav.com/airport/kpne&quot; rel=&quot;noreferrer&quot;&gt;KPNE&lt;/a&gt; they have 2 runway options (6-24 and 15-33) they would use what ever was the best runway for the wind that day unless you needed the precision approach on 24. This made landing there easy (150 x 5000 or 7000 helped as well) as there was never really more than a 15 degree crosswind. I now fly out of &lt;a href=&quot;http://www.airnav.com/airport/KDYL&quot; rel=&quot;noreferrer&quot;&gt;KDYL&lt;/a&gt; which is a single runway airstrip that almost always has a crosswind, really keeps you on your toes.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Crosswind_landing&quot; rel=&quot;noreferrer&quot;&gt;Cross wind approaches&lt;/a&gt; are perfectly safe and are not out of the ordinary. I have seen some people mistake the phrase &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight&quot; rel=&quot;noreferrer&quot;&gt;Uncoordinated Flight&lt;/a&gt; as meaning a sideslipped crosswind landing is unsafe which is incorrect. The plane can be uncoordinated because it is &lt;a href=&quot;https://en.wikipedia.org/wiki/Slip_(aerodynamics)&quot; rel=&quot;noreferrer&quot;&gt;side slipping&lt;/a&gt; to the landing which is done deliberately by the pilot.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-28T17:47:56.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17312" PostTypeId="2" ParentId="17289" CreationDate="2015-07-27T16:51:51.007" Score="9" Body="&lt;p&gt;Virtually never in most aircraft. Afterburners usually increase fuel consumption by a factor of between five and ten from maximum non-afterburning throttle (&quot;full military power&quot;), while the speed increase is often less than double. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was one singular aircraft designed to use afterburners efficiently, the SR-71. Essentially it was designed with a &quot;bleed bypass&quot;; at speeds beyond about Mach 1.5, air in the first compressor stage was diverted behind the combustion chamber using a series of ducts, where the afterburner would then have cleaner air to burn. This drastically improved the efficiency of the engine's afterburner, making it effectively a ramjet design. I can't say whether its range was improved by the use of afterburners, but the pre-bypass speed was limited to around Mach 1.8 while the afterburning speed was greater than Mach 3.3, almost a 100% speed increase and unmatched by any air-breathing craft that has flown since.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-27T16:51:51.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17313" PostTypeId="2" ParentId="17231" CreationDate="2015-07-27T17:02:09.497" Score="1" Body="&lt;p&gt;As altitude increases, the primary effect on aircraft is the reduced density of the air it flies through. A reduction in air density has three key effects on flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Power at a constant setting decreases, because the air-breathing engines we use have less air to use for combustion and to push against.&lt;/li&gt;&#xA;&lt;li&gt;Lift also decreases for the same reason; the aerodynamic lift surfaces (wings) are pushing less air and therefore the forces pushing the wings (and the rest of the aircraft) upward are reduced at a given angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;Drag is decreased, because less air means less friction drag and weaker wake vortices. This is usually offset somewhat by the need to increase angle of attack, which increases induced drag.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, as the air thins, your engines produce less power, but you need less power because your drag is reduced, but that's offset by the need to pitch up to regain lost lift. The net results are an overall decrease in aircraft performance (ability to climb/turn and max speed), but (to a point) increased fuel efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last effect is a reduction in temperature. By the ideal gas laws, cooler air is denser than warm air at a constant pressure, however the equation is dominated by the reduction in pressure.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-27T17:02:09.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17314" PostTypeId="2" ParentId="13015" CreationDate="2015-07-27T17:18:40.657" Score="1" Body="&lt;p&gt;I'm a little surprised that no one mentioned Link-4A.&#xA;I was in the Navy in the late 70's and early 80s, and even then, while I only worked on shipboard Link-11 systems, I heard stories of the related Link-4A system which was used for Aircraft control and communication.&#xA;Link-4A had a mode that could auto land aircraft even back then, so it isn't anything new.&#xA;From a navy pub at &lt;a href=&quot;http://firecontrolman.tpub.com/14103/css/14103_66.htm&quot; rel=&quot;nofollow&quot;&gt;http://firecontrolman.tpub.com/14103/css/14103_66.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Automatic Carrier Landing System&lt;/strong&gt;:&lt;br&gt; The   automatic   carrier   landing   system   selects aircraft in the order of priority from the pattern and enters them into the final approach. During the final approach, a precision radar tracks the aircraft. Correct information pertaining to the approach is transmitted to   the   aircraft’s   autopilot.   When   conditions   are unfavorable  for  a  landing,  the  wave-off  control  is initiated  and  the  aircraft  is  guided  through  a  short pattern and the landing approach is repeated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But it was also my understanding at that time, the pilots did not care for the system at all. No one would really like the controls taken out of their hands for such a critical portion of the flight.&lt;/p&gt;&#xA;" OwnerUserId="9548" LastEditorUserId="5517" LastEditDate="2015-07-27T18:13:40.880" LastActivityDate="2015-07-27T18:13:40.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17315" PostTypeId="2" ParentId="15956" CreationDate="2015-07-27T17:37:33.680" Score="5" Body="&lt;p&gt;They used to use those ordinal class names (first, second, third), borrowed originally from train and ocean liner class designations. British railway classes were first, second and third classes, while ocean liners typically had first, second and steerage (which itself became a derogatory term that was changed to &quot;third class&quot;, especially as steerage evolved from a converted section of cargo space to purpose-built passenger accomodations).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The change to the modern airline classes is an example of the euphemism cycle, and occurred through the 1960s and 1970s as travel in general increased dramatically while the average income of the travelers nose-dived. In the U.S., the primary driver was the stigma of people in those sections being called &quot;second class&quot; or &quot;third class&quot; as &quot;political correctness&quot; started becoming a big thing with the civil rights disputes. This led to a rebranding of lower numbered classes by airlines; second class, being a popular choice for frequent flyers on corporate business seeking a compromise between the low cost of the economy section and the amenities of first class, was renamed &quot;business class&quot;, while the main passenger cabin holding the bulk of passengers with the lowest-cost tickets (average Joes going on vacation, visiting family or just needing to get somewhere on a short travel schedule) was called &quot;coach&quot;, &quot;economy&quot; or simply &quot;standard&quot;. All of these terms have survived at least informally, but &quot;economy&quot; is the one most often used by the airlines to denote this service level.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-27T21:20:56.890" LastActivityDate="2015-07-27T21:20:56.890" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17316" PostTypeId="1" AcceptedAnswerId="17325" CreationDate="2015-07-27T19:04:50.367" Score="6" ViewCount="842" Body="&lt;p&gt;I like to use flight following whenever possible because who wouldn't want traffic pointed out to them for free? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But just as the controllers are doing me a favor, they sometimes ask me to do them a favor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, depending on a given runway configuration, they might vector me way far out from the airspace. During times like these I end up just wanting to terminate. I'm far clear of the class C, and they've added 20 minutes to my flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is it that they move me so far away when plenty of aircraft who didn't even bother to call up approach are flying so freely without incident? To anticipate objection, this is while staying out of the charlie itself. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anything I can do to ask if I can change altitude to avoid rerouting? I'd hate to call up, have them assign me a squawk, and then say &quot;like to terminate&quot; moments later. &lt;/p&gt;&#xA;" OwnerUserId="9418" LastEditorUserId="19" LastEditDate="2017-01-25T10:32:51.790" LastActivityDate="2021-03-02T03:10:27.343" Title="Is there a &quot;Quid Pro Quo&quot; of flight following?" Tags="&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17317" PostTypeId="1" AcceptedAnswerId="17319" CreationDate="2015-07-27T19:14:33.433" Score="7" ViewCount="876" Body="&lt;p&gt;&lt;a href=&quot;https://youtu.be/H6UHAl1Ysyg?t=2m32s&quot; rel=&quot;nofollow noreferrer&quot;&gt;In this video (marker 2:32)&lt;/a&gt;, you can see that the captain has a tablet mounted to his left with some sort of application open in it. It looks like an iPad (though I could be wrong), but what I'm mostly wondering is what that application is he has open, and what it's being used for?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Just to make peoples lives as bit easier, here's a screen cap from 2:32:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/35fVd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/35fVd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-27T19:51:18.263" LastActivityDate="2015-07-27T20:41:08.500" Title="What is the tablet/application being used in this 737?" Tags="&lt;commercial-aviation&gt;&lt;avionics&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17318" PostTypeId="2" ParentId="17317" CreationDate="2015-07-27T19:29:56.267" Score="1" Body="&lt;p&gt;According to this &lt;a href=&quot;http://www.bbc.co.uk/news/technology-32513066&quot; rel=&quot;nofollow&quot;&gt;BBC News report&lt;/a&gt;, American Airlines uses an app called &quot;FliteDeck&quot; on a tablet computer, to avoid pilots having to carry multiple kilograms of documents with them. It says AA saves over a million dollars a year in fuel bills from not carrying all that paper around.  The app contains charts and things like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airlines use similar systems so that's probably what we're seeing in Air Vanuatu cockpit in the video.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-07-27T19:29:56.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17319" PostTypeId="2" ParentId="17317" CreationDate="2015-07-27T19:39:13.937" Score="6" Body="&lt;p&gt;The screens on both electronic flight bags show airspeeds, which would indicate performance data. Specifically, the first officer has a speed card up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't say for certain, but I think the pilot is using the iPad version of the &lt;a href=&quot;https://itunes.apple.com/us/app/boeing-onboard-performance/id584211407?mt=8&quot; rel=&quot;nofollow&quot;&gt;Boeing Onboard Performance Tool&lt;/a&gt;. This application is used for weight and balance and performance calculations (which is especially appropriate, since they're flying a Boeing aircraft).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-07-27T20:41:08.500" LastActivityDate="2015-07-27T20:41:08.500" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17320" PostTypeId="1" AcceptedAnswerId="17331" CreationDate="2015-07-27T19:49:26.780" Score="7" ViewCount="1022" Body="&lt;p&gt;In &lt;a href=&quot;https://youtu.be/ZvE7pnWwCWg&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;noreferrer&quot;&gt;B738&lt;/a&gt; starts takes off without the plane's pressurization system engaged.  The video specifically notes that &lt;a href=&quot;https://youtu.be/ZvE7pnWwCWg?t=10m39s&quot; rel=&quot;noreferrer&quot;&gt;the craft is being pressurized fairly soon after the takeoff has happened&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this because of the icing conditions they had on the ground?  Or is there another reason why it would take off unpressurized? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Screen capture for the extremely busy:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sjege.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sjege.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-27T20:12:31.650" LastActivityDate="2015-07-28T08:20:02.877" Title="Why do some commercial flights start off unpressurized?" Tags="&lt;takeoff&gt;&lt;cabin-pressure&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17321" PostTypeId="2" ParentId="17320" CreationDate="2015-07-27T20:01:44.143" Score="-2" Body="&lt;p&gt;The air pressure outside decreases as the aircraft climbs. However up until a certain altitude, which I happen to forget, you can fly without the aircraft being pressurized. This is why we don't need to throw on oxygen masks while flying light aircraft (up until a certain altitude anyways)&lt;/p&gt;&#xA;" OwnerUserId="9538" LastActivityDate="2015-07-27T20:01:44.143" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17322" PostTypeId="2" ParentId="17302" CreationDate="2015-07-27T20:03:45.527" Score="2" Body="&lt;p&gt;Yes, pilots are trained for crosswind landings. I trained on a Cessna 172 as Paso Robles. The video was completely normal. A roll of &amp;lt; 10 degrees is not serious at all, well within a competent pilot's operational abilities. The news story was written by someone who doesn't fly, thought it looked 'scary' and filled 90 seconds with nonsense, IMO.&lt;/p&gt;&#xA;" OwnerUserId="9551" LastActivityDate="2015-07-27T20:03:45.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17323" PostTypeId="2" ParentId="3871" CreationDate="2015-07-27T20:09:36.880" Score="0" Body="&lt;p&gt;Turn into the wind so you continue on a course parallel to (better directly over) landing runway. Eyeball. No computation required. As you flare, kick rudder to swing nose over runway centerline as you descend. If you time it correctly, you'll land rolling forward down the runway rather than taxiing off across it.&lt;/p&gt;&#xA;" OwnerUserId="9551" LastActivityDate="2015-07-27T20:09:36.880" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17324" PostTypeId="2" ParentId="17294" CreationDate="2015-07-27T20:13:52.610" Score="0" Body="&lt;p&gt;In addition to needing structural strength to hold in a greater amount&#xA;of pressure, the airframe will undergo repeated stress cycles due to&#xA;alternating conditions of equal pressure (on the ground) and&#xA;low outside pressure with high inside pressure (at cruise altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making the stress cycles deeper (by increasing the pressure difference&#xA;without changing airframe structure) can &#xA;&lt;a href=&quot;http://aerostudents.com/files/aircraftStructures/aircraftStructuresFullVersion.pdf&quot; rel=&quot;nofollow&quot;&gt;cause more rapid failure of the fuselage.&lt;/a&gt;&#xA;Reducing the stress means increasing the material you put into the fuselage,&#xA;but almost surely not by just adding a few reinforcements and&#xA;(I think) not generally even by just making everything stronger.&#xA;To safely increase the pressure difference, I think you'd need to&#xA;substantially redesign all the parts of the airframe that hold in the&#xA;pressure (potentially down to individual panels and rivets),&#xA;and then sacrifice an airframe to run a lengthy test&#xA;of pressurization cycles to verify that it doesn't fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems reasonable to do such a thing for a completely new model&#xA;(such as the Dreamliner), where you already have to do that amount of design&#xA;and testing for &lt;em&gt;some&lt;/em&gt; level of pressurization, &#xA;but I think you'd need a stronger incentive&#xA;to redesign an older model in that way, and retrofitting existing&#xA;aircraft would (I suspect) be prohibitively expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TL;DR: with a completely new aircraft design, maybe (if you consider it&#xA;worth the cost); with existing airliners, no.&lt;/p&gt;&#xA;" OwnerUserId="3831" LastActivityDate="2015-07-27T20:13:52.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17325" PostTypeId="2" ParentId="17316" CreationDate="2015-07-27T20:27:47.677" Score="10" Body="&lt;p&gt;There is indeed a Quid Pro Quo with flight following: you're adding to the controller's workload, and they may ask you to do things to help alleviate that workload (like not flying through a busy approach/departure corridor).&lt;br&gt;&#xA;Some controllers will also vector you around a hot MOA (even though you can fly through it VFR their normal operating mode is for IFR traffic) while others will simply alert you that the MOA is hot and leave it up to you to decide how to handle that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because there's no language in the ATC manual for &quot;Hey could you please fly around this area so you don't make my job harder?&quot; when controllers want to ask you to do something they use the language they do have, which takes the form of instructions (vectors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot you should remember that vectors are the opening round in a negotiation: If a controller gives you a vector you don't like you can always ask them why, and often you can negotiate for something better.&lt;br&gt;&#xA;This is true for IFR flights as well - The only exception is when a controller uses the word &quot;Immediate&quot; or any variation thereof (then you do what they say and ask your questions later).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you know you'll be flying through an arrival or departure path you can offer to change your altitude to stay out of the way. Your handy VFR Sectional or Terminal Area Chart shows some of the arrival and departure paths for busier airports:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PnsMi.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PnsMi.png&quot; alt=&quot;TAC excerpt&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;If you offer a climb or descent controllers will usually tell you what altitude they need you at so you aren't in the way, and if they're not forthcoming you can ask (&quot;What am I being vectored around? Can I go through at a different altitude?&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally remember that as a VFR flight you are under no obligation to accept their vectors in Class E airspace: If you don't like what the controller is asking you to do and can't negotiate something better simply say &lt;code&gt;We'd like to cancel flight following at this time&lt;/code&gt; and continue on your own navigation (keep listening to the frequency to see what they do and maybe you'll come up with better alternatives for your next flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controllers may grumble about it, particularly if they just put you into the system and you immediately cancel services, but that isn't your problem.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-07-27T20:44:46.970" LastActivityDate="2015-07-27T20:44:46.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17328" PostTypeId="1" CreationDate="2015-07-27T21:15:58.870" Score="6" ViewCount="2102" Body="&lt;p&gt;How do the pilot and copilot of a large commercial jet operate the radio when talking to ATC? Is there a push-to-talk button, or some voice-triggered mechanism?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, how do they coordinate it? How do they decide which pilot should be talking to ATC?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="11215" LastEditDate="2018-05-14T14:02:24.907" LastActivityDate="2018-05-14T14:02:24.907" Title="How do pilot and copilot operate and coordinate the radio?" Tags="&lt;commercial-aviation&gt;&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17329" PostTypeId="2" ParentId="17328" CreationDate="2015-07-27T21:21:19.903" Score="5" Body="&lt;p&gt;Both yokes have PTT buttons. Generally one person is in charge of the communications. In military aircraft that is often the task of the navigator in twin crew airplanes. I would think it generally falls on the pilot not flying the aircraft although both should be listening to the instructions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The switch is on the front of the yoke (reverse side from what the pilot sees) and is generally triggered with the left index finger. Here is a pic from a yoke for reference. Note the button on the left upper part labeled &quot;mic&quot;.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/GS2VF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GS2VF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.737yoke.com/products.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have never seen it (but then again there are many radios I have not seen) but some radios may have a VOX (voice-operated transmit) option which would bypass the PTT. This however would be very irritating on the channels since there are lots of planes on a single frequency talking to the tower. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-27T21:25:39.347" LastActivityDate="2015-07-27T21:25:39.347" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17330" PostTypeId="2" ParentId="17328" CreationDate="2015-07-27T21:31:14.790" Score="2" Body="&lt;p&gt;The headsets worn by each flight crew member typically feed into an integrated comms/cockpit voice recorder system, where whoever is wearing a headset (and the CVR) will always hear:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;anyone else wearing a headset,&lt;/li&gt;&#xA;&lt;li&gt;the frequency(cies) being monitored on the comm stack, and&lt;/li&gt;&#xA;&lt;li&gt;the flight attendant handsets (if active and patched to the flight deck).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is then a PTT button for each headset (usually on the yoke for pilots, back when there was a flight engineer his was a button on his desk or clipped to his uniform) allowing transmission on the selected COM frequency. In simpler systems the entire &quot;cockpit loop&quot; is transmitted, while more complex radio systems provide degrees of isolation so other members of the flight crew can talk while the radio is open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as who talks to ATC, that's usually worked out between the members of the flight crew, so it can vary between flight crews and also depends on the phase of flight, which one is the pilot flying etc. In some crews the pilot flying is also the pilot talking, while in other crews the pilot not flying (if not on &quot;in-seat rest&quot;) will handle secondary tasks including navigation and radio.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-27T21:31:14.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17331" PostTypeId="2" ParentId="17320" CreationDate="2015-07-27T21:48:59.437" Score="9" Body="&lt;p&gt;The 737 like most modern airliners (notable exception, the 787) is pressurized by bleed air, from either the engines or the APU. Drawing bleed air from the engines reduces the thrust available for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From most common to least common, takeoff configurations are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine bleeds on (supplying bleed air to the pneumatic system), APU off. This is a pressurized takeoff &amp;amp; generally the most common scenario.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine bleeds off, APU bleed supplying air to the pneumatic system. This also results in a pressurized takeoff, with more engine thrust available. Used when max thrust is desired, typically due to heavy weights, short and/or contaminated runways, close-in obstacles requiring steep climb gradients, and similar circumstances.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In the case that the APU is inoperative but taking off with the engine bleeds off is still required, you get:&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;Engine bleeds off, APU bleed off. This results in the unpressurized takeoff referenced in the question.  At a suitable altitude (typically 2000 to 3000 feet into the climb, a minute or two after takeoff), the engine bleeds are turned back on &amp;amp; the aircraft pressurizes normally.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This is uncommon, but still considered a normal procedure (not an abnormal one out of the QRH).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.b737.org.uk/pneumatics.htm&quot; rel=&quot;noreferrer&quot;&gt;Link to Pneumatic System description for the 737&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=7&amp;amp;ved=0CDoQFjAGahUKEwiT5Kfv1vzGAhUCID4KHXjrAG4&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DB737-Air_Conditioning_Systems_Summary.pdf&amp;amp;ei=cdu2VdPnA4LA-AH41oPwBg&amp;amp;usg=AFQjCNGP-5tlr5_kAdPmDGwL6MdCnwiEdA&amp;amp;sig2=aWlCFWihe4GOfmKXPbP5tA&amp;amp;bvm=bv.98717601,d.cWw&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Link to PDF discussing pneumatics &amp;amp; pressurization on the 737&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="100" LastEditDate="2015-07-28T08:20:02.877" LastActivityDate="2015-07-28T08:20:02.877" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17332" PostTypeId="2" ParentId="17328" CreationDate="2015-07-27T22:59:43.527" Score="1" Body="&lt;p&gt;On Boeing airplanes, flight duties are divided in PF (Pilot Flying) and PM (Pilot Monitoring). This duties are defined at the beginning of the flight because it determine the &quot;area of responsibility&quot; for each pilot during all the flight or for phases of flight (for example: Captain can be PF during taxi and PM during the rest of the phases of flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the area of responsibility for the PM, include the duty of COMMUNICATIONS, so this pilot is the one responsible for talking on the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the cockpit preparation the Captain determine which pilot will be the PF and the PM for the flight (or for the each phase of flight), so in that way every crewmember knows what are their duties, and who is going to be in charge of the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know the exact terms for PF and PM for other type of aircraft (I think that for AIRBUS is Pilot Flying and Pilot Not Flying) but I think this flight duty division works for all types...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps...&lt;/p&gt;&#xA;" OwnerUserId="9511" LastActivityDate="2015-07-27T22:59:43.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17333" PostTypeId="2" ParentId="17263" CreationDate="2015-07-27T23:08:06.483" Score="6" Body="&lt;h2&gt;Nope, sorry! If you need a flight review, use an LSA you have been endorsed for.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.56&quot; rel=&quot;nofollow&quot;&gt;§61.56(c)(1)&lt;/a&gt; states that a flight review must be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Accomplished [...] in an aircraft for which that pilot is rated&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Frequently-Asked-Questions-About-Sport-Pilot#pilots&quot; rel=&quot;nofollow&quot;&gt;According to the AOPA&lt;/a&gt; (note: this article is specifically targeted at non-Sport pilots):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Rated is interpreted as category and class&lt;/strong&gt; &lt;em&gt;[emphasis mine]&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And in &lt;a href=&quot;http://www.aopa.org/Advocacy/Regulatory-,-a-,-Certification-Policy/Regulatory-Brief-Sport-Pilot-Light-Sport-Aircraft-Final-Rule&quot; rel=&quot;nofollow&quot;&gt;another article&lt;/a&gt;, the AOPA continues:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sport pilot certificates will be issued without category/class designation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...and just for the final nail in the coffin, here's the FAA itself (thanks, @Pondlife!), in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2061-98B.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 61-98B&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A pilot who holds only a sport pilot certificate may only take a flight review in a light sport aircraft for which he or she holds an operational privilege. For example, a sport pilot who holds airplane privileges could not take the flight review in a Cessna 172 since that airplane is not a light sport airplane and he or she does not hold operating privileges for that airplane. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Long story short, this all means that &lt;strong&gt;no&lt;/strong&gt;, a Sport Pilot cannot perform a flight review in a non-LSA type. Because you require specific logbook endorsements in make/model for category/class/speed (an LSA like a &lt;em&gt;Sting S3&lt;/em&gt; vs &lt;em&gt;Airplane Single-Engine Land&lt;/em&gt;), you are not rated to fly a Cessna 172, for example. Your solo endorsement isn't a rating, as it isn't part of a certificate - it's an endorsement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you become a Private Pilot, you'll be able to do a flight review in &lt;em&gt;almost any ASEL type&lt;/em&gt;, including &lt;em&gt;all LSAs&lt;/em&gt; because you're suddenly rated for the &lt;strong&gt;&lt;em&gt;Airplane&lt;/em&gt;&lt;/strong&gt; category and &lt;strong&gt;&lt;em&gt;Single Engine Land&lt;/em&gt;&lt;/strong&gt; class, with no light-sport-only limitation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can tell, your student pilot certificate is actually invalid. It's been superseded by your Sport Pilot certificate and you are now adding privileges to that certificate. As such, it doesn't really matter that you've been endorsed for solo in a 172; you aren't &lt;em&gt;rated&lt;/em&gt; to fly one in the same way you are for an LSA. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-07-29T15:11:06.387" LastActivityDate="2015-07-29T15:11:06.387" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17334" PostTypeId="2" ParentId="2405" CreationDate="2015-07-28T01:36:44.103" Score="3" Body="&lt;p&gt;At high speeds a large downward aileron deflection can cause the laminar flow to separate from the top of the wing and become turbulent. At this point the wing essentially ceases to produce lift, whereas the other wing has an upward aileron deflection and continues to produce lift. This rolls the aircraft in the opposite direction than intended. I have experienced this in a C152 aerobat while recovering from a steep dive, there is some buffeting and a slow roll opposite to the control input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also heard that at trans-sonic speeds control inputs can precipitate shock waves on parts of the airframe that can cause control reversal without laminar flow separation. But I have not experienced this in a C152 (yet).&lt;/p&gt;&#xA;" OwnerUserId="9519" LastActivityDate="2015-07-28T01:36:44.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17335" PostTypeId="1" AcceptedAnswerId="17337" CreationDate="2015-07-28T02:39:06.170" Score="6" ViewCount="819" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Heat_of_combustion#Higher_heating_value&quot; rel=&quot;noreferrer&quot;&gt;Lower and Higher Heat Values&lt;/a&gt; (LHV or HHV) seem to have multiple definitions based on things I can't figure out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I want to know is, which one is appropriate to use for calculating the thrust from a jet engine? I'm thinking of large commercial turbofan engines like on the 747 or A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, since water vapor seems to have something to do with it, what about jet engines that run on hydrogen like the experimental &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-155&quot; rel=&quot;noreferrer&quot;&gt;Tu-155&lt;/a&gt;? Should we use LHV or HHV to calculate thrust in those engines?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="62" LastEditDate="2015-07-28T11:58:58.167" LastActivityDate="2015-07-28T11:58:58.167" Title="Is LHV or HHV used for calculating the thrust of a jet engine?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="17337" PostTypeId="2" ParentId="17335" CreationDate="2015-07-28T10:16:19.720" Score="8" Body="&lt;p&gt;The difference between both values is the energy set free when the water created by the combustion process condenses. Use the lower heat value for jet engine calculations. The water in a jet engine leaves it as vapor, and the vaporisation heat is lost for propulsion.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-07-28T10:16:19.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17338" PostTypeId="1" AcceptedAnswerId="17339" CreationDate="2015-07-28T12:31:00.840" Score="6" ViewCount="5882" Body="&lt;p&gt;I was trying to understand Slat and Flap control Unit and came across the term &quot;skew sensor&quot;. Can anyone explain it to me?&lt;/p&gt;&#xA;" OwnerUserId="9564" LastEditorUserId="7532" LastEditDate="2015-07-28T14:26:09.970" LastActivityDate="2015-07-28T14:26:09.970" Title="What is the function of a skew sensor in an aircraft?" Tags="&lt;flight-controls&gt;&lt;avionics&gt;&lt;flaps&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17339" PostTypeId="2" ParentId="17338" CreationDate="2015-07-28T13:47:33.770" Score="9" Body="&lt;p&gt;Skew is essentially when the flap doesn't extend or retract straight back.&lt;/p&gt;&#xA;&lt;p&gt;Picture a situation where you have a 1 meter wide board you're pushing down a track that's slightly wider than the board.  Your left hand is about a quarter of the way in from the left edge, and your right hand similarly in from the right edge.  As long as you push straight down the track, evenly, with both hands, the board slides along and doesn't contact the edge.  Now suppose that your right hand pushes harder than your left hand: the board will start to turn, and the edges of the board will contact the edges of the track.&lt;/p&gt;&#xA;&lt;p&gt;The skew sensor detects that this sort of misalignment is starting to happen, and causes the flap drive to stop.  Ideally, this takes place before the flap makes physical contact with any other hardware, so nothing is damaged!&lt;/p&gt;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=cld62K4ntbk&quot; rel=&quot;noreferrer&quot;&gt;Video of flaps being extended &amp;amp; retracted on the ground&lt;/a&gt;.  You can see that there are multiple flaps on each wing, and while normally everything moves in synch, you can envision how if one actuator stopped working, the errant flap could get turned pretty far out of alignment, make contact with other hardware, and cause some significant damage.  So before this happens, the skew sensor sends the command back to stop everything from moving.&lt;/p&gt;&#xA;&lt;p&gt;From Boeing's &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_06/m/m01/story.html&quot; rel=&quot;noreferrer&quot;&gt;Aero Magazine&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The 757-300 has incorporated a flap skew detection system. Flap skew occurs when either the inboard or outboard edge of the flap moves farther than the rest of the flap. The flap skew detection system monitors, detects, and shuts down the flaps if a skew condition occurs. The heart of this system is the flap slat accessory module (FSAM), taking the place of the flap slat electronic unit (FSEU) number 3. The new LRU was introduced because the existing configuration of the FSEU would not accommodate the addition of the flap skew circuits.&lt;/p&gt;&#xA;&lt;p&gt;The flap skew sensors are mounted on the trailing edge of the flap jack screws (fig. 4a). The sensor (fig. 4b) is fixed to the flap track, and a target (which contains magnets) is mounted to the jackscrews. As the jackscrew begins to turn, the target also turns. This will pulse the sensor, and a signal (distance traveled) is sent to the FSAM, which compares this signal with the opposite side of the same flap. If the distances traveled by either side of the flap differ by a predetermined amount, the FSAM will shut down the flap system to help eliminate damage to the flap and surrounding structure and the possible loss of a flap in flight. The alternate flap mode will override the normal flap skew detection function, allowing maintenance personnel to move the flaps after maintenance has been performed. Maintenance personnel must verify the flap fault and also ensure that moving the flap will not cause any damage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-28T14:11:26.747" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17340" PostTypeId="1" AcceptedAnswerId="17341" CreationDate="2015-07-28T13:57:04.000" Score="20" ViewCount="5159" Body="&lt;p&gt;There are various full service carriers (FSCs) who have a separate low-cost carrier (LCC) subsidiary. For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Germanwings&quot;&gt;Germanwings&lt;/a&gt; by &lt;a href=&quot;https://en.wikipedia.org/wiki/Lufthansa&quot;&gt;Lufthansa&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_India_Express&quot;&gt;Air India Express&lt;/a&gt; by &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_India&quot;&gt;Air India&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/JetKonnect&quot;&gt;JetKonnect&lt;/a&gt; by &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_Airways&quot;&gt;Jet Airways&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why do the FSCs prefer to launch a separate LCC, rather than providing seats at a cheaper rate with reduced comforts within their existing structure?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2015-07-28T15:26:49.893" LastActivityDate="2015-07-29T22:04:48.987" Title="Why do full service airlines prefer to run a separate low-cost carrier?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;low-cost-carrier&gt;" AnswerCount="5" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17341" PostTypeId="2" ParentId="17340" CreationDate="2015-07-28T14:14:29.050" Score="37" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They still want to get into the low cost segment but want to market themselves differently for better penetration. You can only present so many images of a brand to customers: You can't show both the super-cheap prices with happy youth on them and posh first class at the same time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They do not want to tarnish a nice brand by mixing it with a low cost carrier and what that is perceived to entail. For instance, Germanwings got a somewhat infamous reputation recently, and Lufthansa is probably happy their name was not more frequently used in media. Low cost is also associated with less good customer service and hidden fees.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Crew are often less well paid, and they are sometimes put under a separate working agreement and company to try to prevent conflicts. Some legacy carriers have very good pay which is difficult to reduce. Management does not want to be bound by these when expanding or adjusting their business.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each case is pretty specific depending on exactly they are trying to do and achieve. For many American Carriers and Lufthansa, the last one is probably the principle reason.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-28T14:51:46.247" LastActivityDate="2015-07-28T14:51:46.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17342" PostTypeId="2" ParentId="17340" CreationDate="2015-07-28T14:15:40.563" Score="10" Body="&lt;p&gt;I would imagine this has to do with branding.  Kind of like how some car companies have both &quot;regular&quot; and &quot;premium&quot; brands.  Eg., Chevy v. Cadillac or VW v. Audi, etc etc.  It allows for companies to have a more exclusive version of their product for people who are just the premium, exclusive sorts... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted there are other cost considerations, and other branding considerations, and I could probably sit here and go on for hours with that but I think it would be a little bit outside of scope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to just give a basic explanation:  Different brands have different associations with them.  Some are seen as premium, exclusive, indulgent.  Others are seen as just hitting the basics.  And some companies will avoid mixing the two just for the sake of brand identity in marketing.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-07-28T14:15:40.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17343" PostTypeId="1" CreationDate="2015-07-28T10:30:50.123" Score="3" ViewCount="508" Body="&lt;p&gt;I have a Cessna 150 which needs a paint job. As I have experience in painting objects with a spray can, and also in stripping airplanes, I am thinking to paint the Cessna myself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the considerations required for this job? I would enjoy the experience and I'm able to get it prepped and ready. What would be a good electrostatic paint machine for this job? And how can I practice before painting the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note, I know the paints are different, I've heard of something called Imron, as well as Epoxy paints that harden and set.  Suggestions on that would be welcome too.&lt;/p&gt;&#xA;" OwnerUserId="9243" OwnerDisplayName="Oliver Williams" LastEditorUserId="65" LastEditDate="2015-07-28T14:43:43.170" LastActivityDate="2015-08-21T12:25:16.870" Title="How do I paint an airplane with an electrostatic paint gun?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17344" PostTypeId="2" ParentId="17340" CreationDate="2015-07-28T14:47:33.467" Score="23" Body="&lt;p&gt;As mentioned there are lots of branding issues around this but there are also lots of corporate and legal reasons to do so. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Business Isolation&lt;/strong&gt;: If you want to start out a bunch of new routes and you are not sure how well they are going to do a large airline my not want to book that kind of loss or risk having to cover it. Thus they can incorporate a &quot;new&quot; airline and protect their existing and profitable business interests should the &quot;new&quot; airline go under. Likewise it also makes it easier, should it be very profitable, to potentially sell it off (or absorb it as well).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Taxes/Fees&lt;/strong&gt;: Tax law changes from place to place so this may differ depending on where they are based but if there are different taxes as a result of company size or specific aviation taxes they may be able to take advantage of them by splitting up. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Legal Isolation&lt;/strong&gt;: I am no lawyer but I am sure that how ever they set these up it isolates the parent airline should anything happen to the other carrier. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Image/Branding&lt;/strong&gt;: this has been touched on already but as mentioned you may not want the image that comes with running a low cost brand associated with your luxury brand.     &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-28T14:47:33.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17345" PostTypeId="2" ParentId="17340" CreationDate="2015-07-28T15:50:22.337" Score="6" Body="&lt;p&gt;As mentioned in earlier answers, branding and management (pay, collective bargaining agreements, etc.) are certainly two major factors. And legacy airlines are mindful of the risk to see their profit cannibalised by the new cheap fares so they need to maintain as much segmentation/price discrimination as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the two strategies are not exclusive. Air France/KLM has several low-cost subsidiaries (Transavia, Transavia-France and HOP!) but also introduced many low-costs tactics (no meal, surcharge for hold luggage…) on short-haul European routes on both legacy airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing is that some elements of the low-cost model (paid refreshments, quick turnaround, routes to cheap airports or use low-cost terminals at major airports, single-class cabin with as many seats as possible, identical aircrafts…) can only be introduced for the whole airplane or even the whole fleet. And for a highly price-sensitive market segment, merely using some elements of the model to offer lower prices is not enough, you need to go all in to ensure your fares are as low as those of your direct competitors (say Easyjet, not necessarily Ryanair).&lt;/p&gt;&#xA;" OwnerUserId="3018" LastEditorUserId="3018" LastEditDate="2015-07-29T22:04:48.987" LastActivityDate="2015-07-29T22:04:48.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17346" PostTypeId="2" ParentId="17302" CreationDate="2015-07-28T16:22:24.967" Score="2" Body="&lt;p&gt;I'm a little late to the party, but here is my take. In that landing I see turbulence but I don't see an obvious crosswind component. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, dealing with crosswinds is something that happens more often than not when landing (at least at many airports and airfields). So every single pilot has dealt with this since the very first days of basic training. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the wing rocking, correcting an off-level wing is probably the very first thing a student learns when getting acquainted with the aircraft's controls. It is completely intuitive for every single pilot.  &lt;/p&gt;&#xA;" OwnerUserId="690" LastActivityDate="2015-07-28T16:22:24.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17347" PostTypeId="2" ParentId="15853" CreationDate="2015-07-28T16:36:07.707" Score="11" Body="&lt;p&gt;EDIT: This first paragraph previously only referenced the Harrier, but I've since found evidence of the Osprey doing the same, and the F-35B has since been reported to perform the feat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only true answers I'm aware of are the &lt;a href=&quot;https://www.youtube.com/watch?v=rC2LFKDiplQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawker Harrier&lt;/a&gt; (or Harrier derivatives thereof), the &lt;a href=&quot;https://www.youtube.com/watch?v=cBF2ZMeqC9w&quot; rel=&quot;nofollow noreferrer&quot;&gt;Osprey&lt;/a&gt;, and the &lt;a href=&quot;https://www.businessinsider.com.au/f-35-pilot-conducts-bizarre-backwards-landing-on-british-carrier-2018-11&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-35B&lt;/a&gt;. These are all VTOL aircraft which can fly backwards, and can also fly very fast forward... thus they are the &quot;fastest&quot; aircraft which can &lt;em&gt;also&lt;/em&gt; fly backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Previously this crown belonged to the Harrier, but since the F-35B is faster it now takes the accolade of being the &quot;fastest recorded backward flying plane&quot;: it can fly backwards, but also fly at mach 1.6.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As to your original question, the answer is that any aircraft is capable of this feat of &lt;strong&gt;&quot;moving in reverse relative to the ground&quot;&lt;/strong&gt;, if the wind speed is higher than that aircraft's stall speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not quite sure what your question is, as you ask what is the fastest plane which can do this: Do you mean &lt;strong&gt;&quot;What is the maximum speed of any aircraft which can achieve this?&quot;&lt;/strong&gt; or did you mean &lt;strong&gt;&quot;How high can this relative speed be&quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the former: With the maximum wind speed recorded on Earth being over 230mph, any aircraft with a stall speed of 230mph or lower (ie, almost any plane), can do it. Therefore the fastest aircraft which can achieve this is the fastest aircraft on the planet. I'm not 100% sure on the fastest aircraft, but the SR-71, for example, can fly at well over Mach 3, but is also capable of flying &quot;backwards&quot; if the wind speed is above around 180 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory the SR-71 could therefore fly at Mach 3 &quot;forwards&quot; or around 50mph &quot;backwards&quot; (in the context of this question) by travelling at 180 knots into a 230mph headwind. I wouldn't recommend attempting this, however....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or to answer the real question I think you're asking which is &lt;strong&gt;&quot;How fast can an aircraft performing this feat travel relative to the ground&quot;&lt;/strong&gt;, the answer would be &quot;the aircraft with the slowest possible stall speed&quot; and the relative speed would be approximately 200mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft which can fly at under 30 knots, flying into that 230mph headwind, would be travelling &quot;backwards&quot; at 200mph relative to the ground, and at 30 knots relative to the wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So actually with it's very low stall speed the An-2 is probably a contender, although I believe there are aircraft with lower stall speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;(Apologies for mixing Knots and MPH almost at random in this reply: all numbers are approximate, however, so it probably doesn't matter too much. For the purposes of this answer, I'm treating 1 kt and 1 mph as approximately equal)&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2019-07-05T11:19:05.923" LastActivityDate="2019-07-05T11:19:05.923" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="17349" PostTypeId="1" CreationDate="2015-07-28T19:07:17.180" Score="13" ViewCount="503" Body="&lt;p&gt;From the &lt;a href=&quot;http://www.ntsb.gov/news/events/Documents/2015_spaceship2_BMG_abstract.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NTSB's preliminary report&lt;/a&gt;, we read in the &quot;Findings&quot; section:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Although the copilot made the required 0.8 Mach callout at the correct point in  the flight, he incorrectly unlocked the feather&#xA;  immediately afterward instead of waiting until SpaceShipTwo reached&#xA;  the required speed of 1.4 Mach.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The unlocking of the feather during the transonic region resulted in uncommanded feather operation because &lt;strong&gt;the external aerodynamic&#xA;  loads on the feather flap&lt;/strong&gt;  assembly were greater than the capability&#xA;  of the feather actuators to hold the assembly in the unfeathered&#xA;  position with the locks disengaged.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Taking into consideration that, as reported &lt;a href=&quot;http://www.theverge.com/2015/7/28/9056423/virgin-galactic-spaceship-crash-cause-tail-wings-feathering&quot; rel=&quot;nofollow noreferrer&quot;&gt;elsewhere&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The vehicle's two tail wings are supposed to move when the spacecraft&#xA;  hits a certain speed, a maneuver known as &quot;feathering.&quot; &lt;strong&gt;This&#xA;  repositioning helps to increase drag&lt;/strong&gt; in order to slow the vehicle down&#xA;  for reentry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the article above, let's also take note of the visual depiction of such configuration change:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gkSaB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gkSaB.png&quot; alt=&quot;SpaceShip2 Feathering&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How is possible that this configuration change, meant to increase drag, needs a &quot;preventing&quot; (for lack of a better word) mechanism? &lt;/li&gt;&#xA;&lt;li&gt;Since the &lt;code&gt;repositioning helps to increase drag&lt;/code&gt;, how do the aerodynamic loads make the repositioning occour?&lt;/li&gt;&#xA;&lt;li&gt;Wouldn't the (additional) drag on the tail section make it go back down again?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-07-29T19:06:36.163" LastActivityDate="2015-07-29T22:05:04.733" Title="How do aerodynamic loads explain the Spaceship2 accident?" Tags="&lt;aerodynamics&gt;&lt;accidents&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17350" PostTypeId="1" CreationDate="2015-07-28T19:47:49.183" Score="15" ViewCount="5519" Body="&lt;p&gt;I have to admit that I’ve always kind of struggled with the Visual Descent Point (VDP) concept. Looking at the Terminal Instrument Procedures (TERPS) definition:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“The VDP is a defined point on the final approach course of a&#xA;  non-precision straight-in approach procedure from which normal descent&#xA;  from the MDA to the runway touchdown point may be commenced, provided&#xA;  visual reference is established.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Fine, I take that to mean that if I start down from Minimum Descent Altitude  (MDA) too far after passing the VDP then my descent won’t be “normal”. What I don’t get is when the VDP is “Not Authorized”. Take a look at the &lt;a href=&quot;http://www.airnav.com/depart?http://155.178.201.160/d-tpp/1508/00982RZ24.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;RNAV (GPS) Z RWY 24&lt;/a&gt; approach for KTTN. Included in the notes is the statement: “VDP NA with Northeast Philadelphia altimeter setting”.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aT1Ps.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aT1Ps.png&quot; alt=&quot;KTTN RNAV (GPS) Z RWY 24&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does that mean? Why is the VDP not authorized now that the MDA is 60 feet higher? If I didn’t want to descend too late before, I certainly don’t want to go past the VDP when I’m 60 feet higher! Is the note just telling me I better have the required visual references in sight so I can start down BEFORE the VDP? That might not be possible if visibility is at the 1 mile minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;@voretaq7:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the implications of altimeter setting from a different airport and how your actual altitude could be higher than indicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess I'm hung up on what it means to &lt;strong&gt;&quot;use&quot;&lt;/strong&gt; the VDP. Assuming that you use the Dive-n-Drive technique (rather than a constant descent rate), then your statement &quot;Fly the approach until you have the runway environment in sight and then figure out your own glide path intercept based on the visual references you have&quot; is what you are going to do regardless of what altimeter setting you use. In that case, what does it mean to &lt;strong&gt;&quot;use&quot;&lt;/strong&gt; the VDP? In a light piston aircraft with airspeed under control, I may prefer to wait until the VDP and make a steeper than normal descent even if my actual altitude if higher than indicated. That way, in poor visibility, I avoid obstacles that may exist below the MDA prior to the VDP. So exactly what is the FAA saying I'm not authorized to do while using the PNE altimeter setting?&lt;/p&gt;&#xA;" OwnerUserId="9566" LastEditorUserId="62" LastEditDate="2016-07-30T13:36:34.110" LastActivityDate="2016-07-30T22:36:03.437" Title="Why is this VDP not authorized?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;terps&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17352" PostTypeId="2" ParentId="15313" CreationDate="2015-07-28T20:23:30.747" Score="8" Body="&lt;p&gt;U.S. military aircraft have multi-mode transponders. within U.S. airspace, they &quot;squawk&quot; using Mode 3, which is identical in its form and operation to civilian Mode C (a four-digit code plus altitude, allowing ATC systems to calculate true distance instead of using slant distance which varies with altitude). While in theater, fighters use enhanced transponder modes that allow for digitally-encoded and even encrypted interrogation/response to prevent false positives, as well as additional information sharing from the INS such as tail number, GPS position, bearing and airspeed, reducing the need for radio communications and radar systems between friendlies. Similar information is also available from civilian planes using Mode S transponders, which most commercial airliners possess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military jets would disable their transponders in the following situations, and very rarely or never in any other:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;By explicit instruction of ATC. A malfunction or an incompatible squawk mode can cause conflicting data on ATC displays, and in certain circumstances even if it is operating properly ATC will tell the pilot to &quot;stop squawk&quot; and track the plane by other means.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When intercepting a plane with TCAS. Traffic Collision Avoidance Systems interrogate nearby aircraft to obtain direction, distance (based on round-trip time) and altitude data from their transponders which it can use to alert the pilot when an aircraft is within minimum separation distances or is on a potential collision course. A military fighter intercepting a civilian aircraft will look like it's on a collision course to the civilian plane's TCAS (it pretty much will be until the interceptor forms up off the beam of the interceptee). This can lead to the pilot of the intercepted aircraft taking evasive maneuvers recommended by TCAS to avoid the potential collision, causing a &quot;dogfight&quot; as the interceptor tries to form up while the interceptee constantly evades. There is a standard squawk code in the U.S. for an intercepting aircraft (0000, 7777 for military) which some TCAS systems will treat differently, but in some cases the interceptor has to at least partially disable their transponder in order to avoid triggering TCAS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When flying in formation. In close formations such as those used during timed flybys at sporting events and airshows, only the flight leader will squawk. This is for two reasons; first, it's redundant for anyone else in the formation to do so, as the composition and layout of the formation can be established by radio contact and nearby traffic advised. Second, ATC radar resolution can be limited especially at longer ranges, so it can be confusing for the ATC's IFF system to interrogate along an azimuth and receive several simultaneous signals.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-01T19:00:15.683" LastActivityDate="2015-08-01T19:00:15.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17353" PostTypeId="2" ParentId="17350" CreationDate="2015-07-28T21:09:19.410" Score="12" Body="&lt;p&gt;The key is in the part of the procedure description I've highlighted:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/iJ5Pk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iJ5Pk.png&quot; alt=&quot;RNAV (GPS) Z RWY 24 Notes&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;code&gt;When local altimeter setting not received use Northeast Philadelphia altimeter setting&lt;/code&gt; -- you're using the altimeter setting for an airport 15 miles away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;15 miles may not seem like a lot of distance, but it's enough for there to be a notceable variation in altimeter settings. The FAA assumes this error will be in the least favorable direction (i.e. your altimeter will indicate you're higher than you really are), and accordingly they take some precautions when you're using another field's altimeter setting.&lt;br&gt;&#xA;In this particular case:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The decision altitudes (DAs) are higher.&lt;/li&gt;&#xA;&lt;li&gt;Baro-VNAV (vertical guidance for your descent based on your altimeter) is not authorized.&lt;/li&gt;&#xA;&lt;li&gt;The use of the charted Visual Descent Point (VDP) is not authorized.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The VDP is telling you &quot;If you are on the approach path and remain at the MDA until over this point on the ground you'll be on the glide path to the runway&quot; (or alternatively &quot;You can plan a constant-rate descent that intersects the MDA over this point and you'll be on the glide path to the runway&quot;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the charted VDP is specifically not authorized in this case because the nominal descent angle you will have passing through it counts on your altimeter being accurate and your aircraft being at the MDA. Since the MDA has changed &lt;em&gt;and&lt;/em&gt; we're using a remote altimeter setting the location of the VDP isn't going to be what's shown on the chart. (For example, if you're 60 feet higher than you &quot;should&quot; be &amp;amp; everything else is perfect the VDP moves further away from the airport to provide the same glide path at a higher altitude).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rather than charting several visual descent points (which would be futile anyway as you can't know the altimeter error portion of the equation) the FAA just says &quot;Don't use it: Fly the approach until you have the runway environment in sight and then figure out your own glide path intercept based on the visual references you have.&quot;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="3825" LastEditDate="2016-07-30T22:36:03.437" LastActivityDate="2016-07-30T22:36:03.437" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17354" PostTypeId="1" AcceptedAnswerId="17355" CreationDate="2015-07-28T21:11:11.023" Score="8" ViewCount="1385" Body="&lt;p&gt;For example, the new B787-8 and B787-9.  Is there any significance in why they started with -8, versus the older 737s which started from -100?  Or B757-200/300?&lt;/p&gt;&#xA;" OwnerUserId="9567" LastEditorUserId="9567" LastEditDate="2015-07-28T21:49:06.563" LastActivityDate="2015-10-09T15:29:07.537" Title="Where do airplane variant numbers come from?" Tags="&lt;airbus&gt;&lt;boeing&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17355" PostTypeId="2" ParentId="17354" CreationDate="2015-07-28T22:32:39.653" Score="13" Body="&lt;p&gt;Chinese superstition. The same reason Airbus went with the 380 number when 350 would have been next in line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Chinese sign for 8 looks like an up arrow (八) and 8 is the lucky number in Chinese. Similarly, 4 (四) is considered unlucky because the word for it (sì) sounds similar to the Mandarin word for death (sĭ).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing and Airbus management court their prospective Chinese customers wherever they can because they expect their biggest sales in the next decade from that part of the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally, Boeing used three-digit numbers for their subtypes, and the last two digits &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Boeing_customer_codes&quot;&gt;represented the airline&lt;/a&gt;. &lt;a href=&quot;https://en.wikipedia.org/wiki/Pan_American_World_Airways&quot;&gt;Pan Am&lt;/a&gt;'s number was 21, for example, so a Boeing 707-100 made to Pan Am specs was a 707-121.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-07-28T22:32:39.653" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17356" PostTypeId="2" ParentId="15807" CreationDate="2015-07-28T22:44:26.627" Score="27" Body="&lt;p&gt;Aerial rearming has been a daydream of military tacticians for decades. However, the task is much more technically demanding than aerial refueling, which is in itself a fairly demanding task for pilot and boom operator just to get a 50-foot fuel hose hooked up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The technical issues include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Physically capturing and docking a smaller aircraft with a larger one.&lt;/strong&gt; The USAF tried it back in the 50s with a B-36 carrying a specially-modified RF-84F. In those days there were no computerized flight controls, and docking the fighter back up with the mothership after it had done its thing proved to be more dangerous to the bomber than just running the mission without a fighter escort at all. It would not be inconceivable for modern avionics to improve on that, however the relative size of fighters compared to larger support craft has increased considerably. Here is a KC-135, built on the &quot;Dash-80&quot; airframe that also sired the 707, refueling an F-15C that's not really &lt;em&gt;that&lt;/em&gt; much smaller when you look at it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Iv5CI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Iv5CI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Placement of most ordinance under the aircraft.&lt;/strong&gt; Most fighters and ground attack aircraft carry weapons on external hardpoints under the wings (the RAF-variant SEPECAT Jaguar being a notable example of both overwing pylons and the insanity of British aircraft designers):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VeU2N.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VeU2N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When in refueling position under a tanker, the aircraft's most deadly weapons are on the wrong side of the jet to try to get to them to replace or reload them. You'd have to either bring the aircraft &lt;em&gt;inside&lt;/em&gt; the mothership, or have it land on top (and provide a sheltered work area for a crew to get to the ordinance pylons).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Relative fuselage width of mothership versus wingspan of fighter.&lt;/strong&gt; The largest fixed-wing craft in the U.S. arsenal is the C-5 Galaxy. It's a &lt;em&gt;big&lt;/em&gt; plane (though not the biggest, that distinction belongs to the Ukrainians with the An-225). Here it is with a couple F-15s and a C-130 parked nearby for scale:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iomru.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iomru.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with a plane this size, able to transport &lt;em&gt;other planes&lt;/em&gt;, you can see from the below photo that neither the F-14 being loaded nor the Galaxy is in a flight-ready condition at the time:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QIIe3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QIIe3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd be interested to see whether one of the light weight fighters (F-16, F/A-18) might fit with less disassembly (the F-18 might if you folded the wings), but it remains that you're just not going to be able to fly a modern fighter into another aircraft in midair, at least not with any currently-flying airframe combination.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Getting crew access to the plane.&lt;/strong&gt; If you've ever seen a ground crew loading a fighter for a mission, you know it's a fairly complex process of not only putting the ordinance (which can weigh up to 2500 pounds for large laser-guided bombs) onto the hardpoints, but wiring up the arming and firing circuits for each one, and programming the plane's FCC with the loadout. This requires getting a lot of people underneath the aircraft (it can take two or three people to load one hardpoint especially if the ordinance has to be muscled into place; here's two people loading probably the lightest piece of external ordinance the USAF has onto an F-15C, and it's only two people because they're using a hydraulic loader):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AolRq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AolRq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft can't be taken inside the mothership (see previous point), the only other possible place for this to be done is on top of the mothership. That means you'd have a crew &lt;em&gt;out on top of the aircraft&lt;/em&gt; muscling ordinance into place. That first requires a sheltered area on top of the mothership that the fighter can be docked and tethered to, as there's no way a crew is getting anything done in a 150-knot headwind. The fuselage vs wingspan difference is important here too; you're not going to be loading AIM-9s onto the wingtips of an F-16 or F-18 when the F-16's wingspan is 33 feet while the cargo deck width (a stand-in for the amount of usable fuselage width) is only 19 feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In summary, loading/reloading an aircraft is a serious operation requiring a dozen people to do quickly and efficiently. Putting those dozen people, and their equipment, &lt;em&gt;and&lt;/em&gt; all the ordinance into a mothership, getting the fighter to safely approach that mothership and touch down on top of it, then getting the crew into position to remove expended hardpoint pylons and reload new ones, &lt;em&gt;then&lt;/em&gt; getting the plane to safely get back off the mothership... It's just not gonna happen with any current technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a proposed design for a twin-fuselage C-5 as a shuttle transport aircraft; the idea was that this aircraft could be used instead of the risky crane system to pick the shuttle off the ground at an alternate shuttle landing site like Edwards AFB:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cu2fz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cu2fz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft of this scale might, &lt;em&gt;might&lt;/em&gt;, be able to support an aircraft coming in between the tails, docking, then using remote arms to load ordinance. This aircraft would, by wingspan, be the largest plane ever to fly, and would compete closely with the An-225 on every other size stat except total length.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="22726" LastEditDate="2019-05-20T03:40:25.470" LastActivityDate="2019-05-20T03:40:25.470" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="17357" PostTypeId="1" CreationDate="2015-07-28T23:09:00.370" Score="13" ViewCount="3113" Body="&lt;p&gt;Assume that you have an aircraft that is &lt;strong&gt;&lt;em&gt;so&lt;/em&gt;&lt;/strong&gt; amazingly stealthy that it is perfectly quiet: no engine noise at all, nothing.  And, it's going supersonic.  (Maybe in a steep dive with the motor shut off.)  Will it make a sonic boom?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would the sonic boom be louder if the aircraft was making more noise but all else remained constant?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The (excellent) answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/2560/do-bigger-aircraft-make-a-bigger-sonic-boom&quot;&gt;this question&lt;/a&gt; discusses aircraft &lt;strong&gt;size&lt;/strong&gt; in relation to the strength of the sonic boom, but no mention of aircraft &lt;strong&gt;noise&lt;/strong&gt;.  So would the amount of noise the aircraft makes matter?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: by &quot;silent&quot; I'm not trying to imply &quot;displaces no air&quot; or creates no sound by its passage.  The point is simply that the aircraft itself doesn't make any noise from an engine or otherwise.  It's silent, like a bullet, or a glider.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2018-02-18T00:03:21.340" Title="Would a perfectly silent supersonic aircraft create a sonic boom?" Tags="&lt;supersonic&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17359" PostTypeId="2" ParentId="17357" CreationDate="2015-07-28T23:51:35.807" Score="33" Body="&lt;p&gt;Sonic booms aren't created by the aircraft's engine noise. They're created by the aircraft moving through the air. The aircraft has a non-zero volume (an aircraft with zero volume is like the emperor's new clothes; you can argue all you want how much design and engineering work it took but all anyone will see is an empty spot on the flight line), meaning it must displace air as the plane passes through air. This displaced air equalizes with the surrounding air in an expanding pressure wave, which moves at the speed of sound in all directions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As your hypothetical silent aircraft approaches the speed of sound, the air being pushed aside can no longer equalize by moving out directly in front of the aircraft. This causes a single strong compression wave to build in front of the aircraft. Similar waves have already started to build over the top of the wing surfaces, as the airflow over the leading edge of the wing (by design intended to make the air move faster thus lowering its pressure and producing lift) is temporarily supersonic before friction causes it to settle back below sonic speed; at this transition point between super- and sub-sonic, air still moving supersonically &quot;backs up&quot; against the subsonic airflow, creating a wall of relatively high-density air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point, an observer would already hear a small sonic boom from some combination of these compression waves. However, the boom becomes much more pronounced as the entire aircraft transitions beyond Mach 1. At this point the &quot;wall&quot; in front of the aircraft becomes more of a &quot;cone&quot; as the air can no longer build up directly in front of the jet and is instead violently pushed aside at any local &quot;disconnect&quot; in the angle presented to the oncoming airflow. This sudden compression produces a strong shockwave &quot;wake&quot; which is what is heard as a sonic boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a perfect example of this, there actually is (was) a vehicle that spends a very critical portion of its flight under zero engine power, effectively silent in that regard, at not only supersonic but hypersonic speeds. This vehicle, as shown in the linked YouTube, produces a characteristic &quot;double sonic boom&quot;, proof that even a &quot;silent&quot; aircraft isn't silent when it's supersonic. Can you guess what it is?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/lNL4HHFG8H4?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The noise of an aircraft's engines could, conceivably, add a little extra to the sonic boom; the biggest difference is that immediately following the sonic boom, if you were close enough, you'd also get the engine noise, which can be deafening all by itself at full throttle up to 100 feet away.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-04T18:24:44.370" LastActivityDate="2015-09-04T18:24:44.370" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17361" PostTypeId="1" AcceptedAnswerId="17362" CreationDate="2015-07-29T00:16:08.167" Score="6" ViewCount="861" Body="&lt;p&gt;I know that you can be &lt;a href=&quot;https://aviation.stackexchange.com/q/13579/65&quot;&gt;a pilot in the U.S. as a foreigner&lt;/a&gt;. However, are there any special regulations regarding citizens of Iran because of political issues?&lt;/p&gt;&#xA;" OwnerUserId="9570" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-30T16:20:27.120" Title="Can an Iranian citizen attain ATP in the United States?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17362" PostTypeId="2" ParentId="17361" CreationDate="2015-07-29T01:08:55.617" Score="12" Body="&lt;p&gt;The U.S. does not prohibit Iranian citizens entering the United States and remaining here on extended business. It also allows noncitizens to attend flight school, conditional on a review of the candidate by the Transportation Security Administration. So, the U.S. would not categorically prohibit an Iran citizen learning to fly and obtaining a commercial or airline pilot's license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, while not impossible, it will be much harder than I just made it sound if you are living in Iran right now, because communications between Iranians and the U.S. State Department have been made difficult by the politics of the past 35 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is, to put it delicately, no functional United States Embassy on Iranian soil. The U.S. maintains a virtual Iranian Embassy online at &lt;a href=&quot;http://iran.usembassy.gov/&quot; rel=&quot;nofollow&quot;&gt;http://iran.usembassy.gov/&lt;/a&gt; (also in Farsi at &lt;a href=&quot;http://persian.iran.usembassy.gov/&quot; rel=&quot;nofollow&quot;&gt;http://persian.iran.usembassy.gov/&lt;/a&gt;); however it was blocked by Iranian information authorities less than 12 hours after it initially opened and remains blacklisted to this day. Users with a VPN tunnel outside Iran's firewall can access it, but the site is mostly educational; you cannot apply for a visa using the site alone. You'd have to be able to submit your paperwork to a functioning U.S. Embassy or directly to the State Department offices in Washington D.C., which will be a delicate process as the Revolutionary Guard will be monitoring both sides of such correspondence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you can establish reliable contact with the U.S. State Department either directly or through an Embassy, you would need an extended visa. There are three basic reasons to stay longer than 90 days, with visa classes for each; work, school, and temporary asylum. If you are coming to the U.S. specifically to learn to fly, an M-1 visa should be what you apply for; it permits entry to the U.S. for &quot;vocational or other non-academic training&quot;, including FAA Part 61 and Part 141 flight schools. The Iranian authorities also look most favorably on student visas compared to other types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the visa, you would, like any other foreign applicant for flight training, be required to pass a TSA security clearance. This is ultimately discretionary; you cannot force the TSA to grant your clearance (ask any U.S. national; you can't force the TSA to do anything). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While neither the State Department, TSA nor the FAA would categorically prevent you learning to fly based on country of origin, the TSA does list Iran as a country of origin that prohibits the visa holder from &quot;Automatic Revalidation&quot;. Essentially, if while attending flight school, you ever left the U.S. (to visit family back home, or even driving north to Canada or south to Mexico for sightseeing) you would be required to go through the full security clearance process again including the TSA check. So, you would have to stay in the United States political borders at all times while in flight school, or you could risk being denied reentry or resumption of your flight training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While taking flight training and amassing your 1000 hours flight time required for an Airline Transport Pilot license (that 1000 hours number is good only if you're attending a four-year flight school; for most civilians working their way up it's 1,500), there are a number of illegal acts you can unintentionally commit while flying. For citizens, the legal penalty for unintentionally breaking an FAA regulation ranges from nothing to a talking to by air traffic control up to formal hearings with possible suspension or revocation of your pilot certificate. For a non-citizen in the United States for the express purpose of learning to fly, any offense bad enough to get your pilot's license suspended would likely also get you deported (if not for the criminal act, then because you can no longer do what you're here to do). But, you'd usually have to mess up pretty bad several times to get that far.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you have your ATPL, your M-1 would no longer be valid as you'd no longer be a student, and so you'd have to leave the U.S. unless you made prior arrangements with the State Department and/or an airline to remain in the country under another status (such as H-1b to work for an airline). If you take your license and leave the country, the FAA ATPL would only allow you to fly &quot;N-numbered&quot; aircraft registered by the FAA. Most other countries have their own registration, and would require you to &quot;convert&quot; your pilot's license to the local regulatory agency's version before you could fly a locally-registered plane. For an ATPL holder this is typically easier than for lower levels, and for the EASA (the largest ICAO-compliant regulatory body besides the FAA) it boils down to a skills test (knowledge and practical), a new medical cert, and being re-rated by the EASA for multi-engine operations (the FAA AMEL class rating does not transfer).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-30T16:20:27.120" LastActivityDate="2015-07-30T16:20:27.120" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17364" PostTypeId="1" AcceptedAnswerId="17371" CreationDate="2015-07-29T02:24:36.673" Score="4" ViewCount="899" Body="&lt;p&gt;Is there any effect on the stealth features due to variable wing geometry? If not, why have such aircraft not been designed till now? Please explain the limitations using any structural principles if possible.&lt;/p&gt;&#xA;" OwnerUserId="7653" LastEditorUserId="3386" LastEditDate="2018-04-24T12:50:56.823" LastActivityDate="2018-04-24T12:50:56.823" Title="Is it possible to use variable wing geometry on a fifth generation stealth fighter?" Tags="&lt;military&gt;&lt;wing&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17365" PostTypeId="1" AcceptedAnswerId="17369" CreationDate="2015-07-29T03:01:54.300" Score="22" ViewCount="2941" Body="&lt;p&gt;What is the proper position for the landing lights when on the runway in a &lt;strong&gt;line up and wait&lt;/strong&gt; position?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="100" LastEditDate="2020-05-11T09:46:49.770" LastActivityDate="2020-05-11T09:46:49.770" Title="Should landing light be off during line up and wait position?" Tags="&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17366" PostTypeId="2" ParentId="17365" CreationDate="2015-07-29T03:17:33.883" Score="4" Body="&lt;p&gt;I’d have it on for visibility. Since you’re on the runway and pointed forwards, no landing airplane will see it, and no airplane in the pattern will be really close. No airplane taking off will see it because they don’t have a rear view mirror.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It means one less thing to do before taking off, and lets you focus on the remaining checklist items before departing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I’d turn it on once in position.&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-07-29T03:17:33.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17367" PostTypeId="2" ParentId="17365" CreationDate="2015-07-29T03:43:46.097" Score="2" Body="&lt;p&gt;If you intend to use your landing lights, there's no reason they should be off as your aircraft crosses the hold short position.  At a minimum it will serve to increase your visibility to other aircraft and service vehicles.  Taxi/ landing light courtesy does not apply to aircraft that are on an active runway.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-07-29T03:43:46.097" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17368" PostTypeId="2" ParentId="17289" CreationDate="2015-07-29T03:56:59.187" Score="21" Body="&lt;p&gt;If such a pair of states does exist it ought to be straddling a Mach boundary (I think)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qMM37.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qMM37.png&quot; alt=&quot;Plots&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. A subsonic &amp;amp; B trans-sonic. Or A trans-sonic &amp;amp; B supersonic etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reasoning: To get from any point A to B in parameter space should usually be a state function i.e. path independent. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. You can give many tiny increments or one large increment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In our context a parameter space means mostly a &lt;code&gt;{velocity(v), altitude(h)}&lt;/code&gt; pair. &#xA;To go from &lt;code&gt;A{v1,h1}&lt;/code&gt; to &lt;code&gt;B{v2,h2}&lt;/code&gt; you need a certain thrust profile. The required thrust profile is not unique. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the above path independance statement is true in general, except when a dissipative force exists. Now you no longer have a state function. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since drag, a dissipative force, is indeed a strong function of speed it will help to not linger in the high drag region i.e. transsonic region with wave drag. In this zone the drag coefficient increases rapidly and you will have a total drag much higher than at both sub-sonic and super-sonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that would give a high thrust afterburner the advantage needed over a dry engine: &lt;em&gt;On afterburner you can zoom through the transsonic region  rapidly than trudge through it incrementally on dry thrust.&lt;/em&gt; Thereby saving on drag losses. You are still consuming more fuel per unit time but the time spent is reduced so much that it makes the higher specific consumption worthwhile. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Caveat: This is just an qualitative argument. A more mathematical argument is needed to add rigor to the analysis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Maybe these schematic plots help clarify my argument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tm0j7.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tm0j7.png&quot; alt=&quot;More Plots&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-07-29T14:20:30.423" LastActivityDate="2015-07-29T14:20:30.423" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17369" PostTypeId="2" ParentId="17365" CreationDate="2015-07-29T04:15:32.823" Score="30" Body="&lt;p&gt;Counter-intuitively, &lt;a href=&quot;http://www.faa.gov/airports/runway_safety/media/pdf/PHAK%20-%20Appendix%201%20-%20April%202012.pdf&quot;&gt;the FAA answer&lt;/a&gt; (see chart on page 1-9 and text on page 1-10) is actually, they should be &lt;strong&gt;off&lt;/strong&gt; during the line-up-and-wait phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When cleared to ...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“Line up and wait”—when entering the departure&#xA;  runway without takeoff clearance, turn on all exterior&#xA;  lights (except landing lights) to make your aircraft&#xA;  more conspicuous. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then when takeoff clearance is received, the expectation is that landing lights will be turned on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best rationale I've seen for this is so that Tower controllers (and other aircraft) have an immediate visual cue that an aircraft &quot;on the numbers&quot; understands that it has been cleared for takeoff, or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another FAA document, &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2011/SAFO11004.pdf&quot;&gt;SAFO 11004&lt;/a&gt; (these are &quot;best practice&quot; recommendations, not requirements):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Exterior Lighting:&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;o Taxi with taxi light on when moving, off when stopped.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;o Turn on all exterior lights when crossing any runway.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;o If cleared to “Line Up and Wait”, turn on all exterior lights except landing lights.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;o When “Cleared for take-off”, turn on all exterior lights, including landing lights&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;o If you see an aircraft in take-off position on a runway with landing lights ON, that aircraft has&#xA;  most likely received its take-off clearance and will be departing immediately. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-07-29T16:56:26.003" LastActivityDate="2015-07-29T16:56:26.003" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17370" PostTypeId="1" AcceptedAnswerId="17372" CreationDate="2015-07-29T07:05:12.763" Score="13" ViewCount="5475" Body="&lt;p&gt;The blade of an helicopter rotor can have three hinges: pitch hinge, flapping hinge and lead-lag hinge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lead-lag (dragging): movement of a blade forward or aft in the plane rotation. Lead lag is facilitated by a lead-lag hinge in the rotor system or through rubber like bearings that allow individual rotor blades to move back and forth in their plane of rotation.&#xA;This helps balance the blade system and reduces vibration. The drag brace or drag damper resists the movement of the blade around its lead-lag hinge on a semi-rigid rotor system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the same plane, we have also the hunting, defined as the tendency of a blade to oscillate ahead of or behind a position which would be determined by centrifugal force alone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why should the centrifugal force alone determine a movement aft and behind the plane of rotation? &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="755" LastEditDate="2015-07-31T18:42:11.007" LastActivityDate="2016-04-03T18:49:41.350" Title="What causes hunting movement in helicopter rotors?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;&lt;rotorcraft&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17371" PostTypeId="2" ParentId="17364" CreationDate="2015-07-29T07:20:46.460" Score="9" Body="&lt;p&gt;Of course it is possible. But it does not improve the outcome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swing wings were a fad of the Sixties. They never fulfilled their early promises, because the actuation mechanism is &lt;strong&gt;heavy&lt;/strong&gt;. Variable sweep is only justifiable when the aircraft will fly both sub- and supersonically for extended periods. It turned out that the part of most missions which is spent at supersonic speeds is a lot smaller than anticipated in the Sixties. Just take the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rockwell B-1&lt;/a&gt;: Designed for supersonic penetration (B-1A) it became a subsonic low-level terrain following strike aircraft (B-1B).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For stealth, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1798/do-similar-angles-on-a-plane-make-it-more-stealthy&quot;&gt;edge alignment&lt;/a&gt; is an important design principle. Making wing sweep variable is to throw this overboard, compromising the whole strategy of stealth. Also, the best stealthiness is only possible in subsonic flight - airframe heating at supersonic speed will broadcast the aircraft's presence to everyone with a low-cost infrared sensor.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-04-17T17:02:35.197" LastActivityDate="2018-04-17T17:02:35.197" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17372" PostTypeId="2" ParentId="17370" CreationDate="2015-07-29T09:42:43.713" Score="13" Body="&lt;p&gt;Lead lag is caused by the blades speeding up and slowing down as they flap up and down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blade on the advancing side experiences an airflow equal to it's speed plus the forward speed of the helicopter.  The blade on the retreating side experiences airflow equal to the speed of the blade minus the forward speed of the helicopter.  This causes &lt;a href=&quot;https://en.wikipedia.org/wiki/Dissymmetry_of_lift&quot; rel=&quot;noreferrer&quot;&gt;dissymmetry of lift&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To counter this, the blades can flap up and down around the flapping hinges.  The blade on the advancing side flaps up, reducing the angle of attack and therefore the lift generated.  The blade on the retreating side flaps down, increasing the angle of attack and therefore increasing lift.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this video at around 1:30 to see &lt;a href=&quot;https://www.youtube.com/watch?v=ki-CxkRuAxY&quot; rel=&quot;noreferrer&quot;&gt;flapping in action&lt;/a&gt;.  This is a gyrocopter, but you can &lt;a href=&quot;https://www.youtube.com/watch?v=7DkgNw3hTKY&quot; rel=&quot;noreferrer&quot;&gt;really see the blades flapping on this one&lt;/a&gt; at 0:39 and 1:17.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to &lt;a href=&quot;https://en.wikipedia.org/wiki/Momentum#Conservation&quot; rel=&quot;noreferrer&quot;&gt;conservation of momentum&lt;/a&gt;, the blade flapping up speeds up as it's centre of gravity moves inwards toward the rotor hub.  Since the rotor is turning at a constant speed, the blade must move forward around the lead/lag hinge.  In a similar way, the blade flapping down slows down so lags.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades will hunt forward and backwards from the neutral position in a sine wave as the rotor rotates.  Lead/lag dampers reduce the force of this hunting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A variation of flapping hinges (independent hinges for each blade) is a teetering hinge on 2 blade helicopters where the hinge is connected to each blade.  If one blade rises, the other must fall and vice-versa.  The entire rotor disc &quot;teeters&quot; on top of the drive shaft.  This is known as a &lt;a href=&quot;http://www.copters.com/mech/mr_semi.html&quot; rel=&quot;noreferrer&quot;&gt;semi-rigid head&lt;/a&gt; and as far as I know, is used on all 2 blade helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In semi-rigid and rigid heads, the overall effect of the blades speeding up and slowing down cancels out in the complete cycle of rotation and other mechanisms are used to reduce the hunting loads.  Imagine a 4 blade rigid rotor.  2 blades are trying to speed up the rotor and 2 are trying to slow it down in equal amounts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One serious side effect of lead/lag on fully articulated heads is &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_resonance&quot; rel=&quot;noreferrer&quot;&gt;ground resonance&lt;/a&gt;.  Since the blades can move forwards and backwards, it is possible for the blades to get closer together on one side than on the other, especially when the helicopter lands with a roll angle, so one gear hits the ground first.  This shifts the centre of balance away from the centre of rotation which can induce a wobble of the rotor head, which translates into a vertical &quot;bounce&quot; vibration at the landing gear. If conditions are right (or wrong, depending on your view point), the resonance can be amplified by the natural resonance frequency of the helicopters landing gear and can lead, if allowed to continue, to the &lt;a href=&quot;https://www.youtube.com/watch?t=38&amp;amp;v=3QgXQ39aL5I&quot; rel=&quot;noreferrer&quot;&gt;destruction of the aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think that helicopter blades are quite rigid, &lt;a href=&quot;https://www.youtube.com/watch?v=srjbnvTWRJI&quot; rel=&quot;noreferrer&quot;&gt;think again&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1961" LastEditDate="2016-04-03T18:49:41.350" LastActivityDate="2016-04-03T18:49:41.350" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17373" PostTypeId="2" ParentId="17349" CreationDate="2015-07-29T10:00:18.523" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How do aerodynamic loads explain the Spaceship2 accident?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aerodynamic load overpowered the actuators holding it in place, forcing it to open and causing SpaceShip2 to break up in flight. Although the rudders were unlocked early when SpaceShip2 was going at Mach 1.0, this action alone should not have been enough to pivot the tails upright, because neither pilot took the further step of turning the feather handle to actually move them. However, the tails rotated upward anyway, and the increase in drag at this point in the flight caused it to crash.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How is possible that this configuration change, meant to increase drag, needs a &quot;preventing&quot; (for lack of a better word) mechanism?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The feather is ultimately there for re-entry. It acts as a hinge and can go up and down. This system increases atmospheric drag on the spaceship so that it naturally positions itself during re entry. To make sure the tail doesn’t move forward early, SpaceShip2 has a structural lock that holds feather in place. Around Mach 1.4, the lock is moved so that the feather is now mechanically free. It won’t move though because at Mach 1.4, aerodynamic forces keep it nailed back. In addition to the lock, the feather itself has a big actuator that drives it up and down. So just because it’s unlocked doesn’t mean it’s just flopping in the wind and it can go where it wants. In the (initial) boost phase, the aerodynamic forces can overcome that, which is why it is  locked .&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How do the aerodynamic loads make the drag naturally increase?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aerodynamic forces are generated by the difference in velocity between the spacecraft and the air. There must be motion between the spacecraft and the air. If there is no relative motion, there is no lift and no drag. In order to maintain a constant airspeed, thrust and drag must remain equal, just as lift and weight must be equal to maintain a constant vertical speed. If in level flight, the engine power is reduced, the thrust is lessened, and the aircraft slows down. As long as the thrust is less than the drag, the aircraft continues to decelerate until its airspeed is insufficient to support it in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Calculations can be found &lt;a href=&quot;http://contrails.iit.edu/DigitalCollection/1966/AFFDLTR66-037part01.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerodynamic forces are used differently on a rocket than on an airplane. On an airplane, lift is used to overcome the weight of the aircraft, but on a rocket, thrust is used in opposition to weight. Because the center of pressure is not normally located at the center of gravity of the rocket, aerodynamic forces can cause the rocket to rotate in flight. The lift of a rocket is a side force used to stabilize and control the direction of flight. While most aircraft have a high lift to drag ratio, the drag of a rocket is usually much greater than the lift.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Wouldn't the drag on the tail section make it go down again?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are two conventional ways to transition from space back to Earth: One is to come in as a winged airplane, like NASA’s space shuttle. In this way the spacecraft can land where it wants, but hitting the perfect angle of attack is tricky. The second method is as a capsule, which is essentially dummy-proof, but has no control over where it lands and subjects its occupants to high G-forces. SpaceShip2 is a bit of both. Its tail folds up and down, changing the vehicle’s shape from something that falls like a capsule to one that flies like an airplane once it’s back in the atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each of the two tails acts as a rudder, and has a small, horizontal flap at the back, extending to the outside. When the plane is descending, both tails can pivot upright, together, from 0 to 90 degrees, so that they stand “vertically” behind the plane. In this configuration, the tails and flaps create drag. When pointed upward, the tails are at right angles to the direction of airflow, creating a huge amount of drag on the vehicle, which slows it down without overheating the spacecraft. This method works because SpaceShip2 is not coming back from orbit.If put in feathered configuration during powered flight, the drag vector and thrust vectors are horribly misaligned, resulting in extreme pitch rates and, since the aircraft wasn't built to withstand those stresses, it would break apart&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="755" LastEditDate="2015-07-29T22:05:04.733" LastActivityDate="2015-07-29T22:05:04.733" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17374" PostTypeId="1" AcceptedAnswerId="17392" CreationDate="2015-07-29T11:56:23.577" Score="38" ViewCount="16191" Body="&lt;p&gt;The double-decker aircraft has failed to win a single &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Airbus_A380_orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;order&lt;/a&gt; from any new airline customer for two years now. Comparing its orders and sales with its biggest competitor, the B747 it had received 315 &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;orders&lt;/a&gt; in its first 10 years, about 40 years back. Today though, the A380 has recieved 317 in its first 8 years, but it failed to receive even a single order in past two years. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“It’s true the market hasn’t developed as much as we’d have liked,” Airbus Chief Executive Officer Fabrice Bregier said this month. “This plane was probably launched 10 years too early.” (&lt;a href=&quot;http://www.bloomberg.com/news/articles/2015-04-26/airbus-a380-haunted-by-lack-of-orders-marks-decade-in-the-skies&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why couldn't the A380 sell as much as the B747, even though it has won many admirers in a shorter period of time. Also, a rough &lt;a href=&quot;http://planes.axlegeeks.com/compare/242-282/Airbus-A380-800-vs-Boeing-747-8&quot; rel=&quot;noreferrer&quot;&gt;comparison&lt;/a&gt; shows A380 is worth its price, when compared to 747-8. But the 747-8 is still getting more &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8#Orders_and_deliveries&quot; rel=&quot;noreferrer&quot;&gt;orders&lt;/a&gt; than the A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Update : Iran Air has finally ordered some A380s in February 2016.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2016-02-21T05:44:02.140" LastActivityDate="2016-12-14T22:03:25.743" Title="Why couldn't the A380 secure any orders for two straight years?" Tags="&lt;boeing-747&gt;&lt;airbus-a380&gt;&lt;aircraft-order&gt;" AnswerCount="8" CommentCount="12" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17375" PostTypeId="2" ParentId="17374" CreationDate="2015-07-29T12:06:30.303" Score="5" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The market for such a huge aircraft is very limited. The big airlines that have interest already have them. When the 747 was introduced, it was an unrivalled aircraft, and there was a booming market.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The A380 is now becoming a 10-year old aircraft in need of a bit of updating. The questionable outlook on orders does not inspire confidence in airlines that such change would take place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 747-8 orders are to some part passenger aircraft (many of the operators also with older versions of the 747, i.e. fleet commonality) but many are also freighter versions where there is nothing in that size category. Even so, the 747-8 is definitely not selling like butter, and they too have cut back production rates numerous times.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-07-29T12:06:30.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17376" PostTypeId="1" CreationDate="2015-07-29T12:35:14.367" Score="2" ViewCount="184" Body="&lt;p&gt;TL;DR: I'm hypothesising the cockpit experience and pay in small aircraft vs larger aircraft is disproportionate to the risk and responsibility.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I read the argument that &lt;strong&gt;pilot pay should be equal across all types&lt;/strong&gt;, irrespective of it is an A320, A330 or A340 for instance.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The smaller aircraft have greater number of rotations every day, leading to greater workload and hence the pilot responsibility could be argued to be equal to that of a larger aircraft which spends (a lot) more time just cruising.&lt;/li&gt;&#xA;&lt;li&gt;The bigger aircraft often operate to better, more equipped airports than their smaller counterparts. This again may put more load and responsibility on the pilots.&lt;/li&gt;&#xA;&lt;li&gt;The bigger aircraft, while in some cases more complicated, may have more automated systems and assistance rather than greater pilot workload, although this of course depends on the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm wondering if anybody (airline, union etc.) has done this or is trying to do implement it. It would be mighty unpopular among some pilots but I think there is a little bit of sense to the argument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why is this a problem?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also causes the least (or less) experienced pilots to command the small aircraft, rather than perhaps a more sensible mix of age and experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paying additionally by the years of experience makes sense to me, but not this push to constantly advance to get a higher salary. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it stands, the only way to make more (aside from years of experience) is to upgrade to a larger aircraft type. Aside from requiring retraining (expensive type rating), it puts the pilot into a new aircraft (and possibly airports) he is unfamiliar with. &lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-07-29T14:13:44.143" LastActivityDate="2015-07-30T16:24:20.970" Title="Have there been any attempts to standardise pay across different aircraft types?" Tags="&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17377" PostTypeId="2" ParentId="17374" CreationDate="2015-07-29T13:59:23.037" Score="28" Body="&lt;p&gt;&lt;strong&gt;It's not as fuel-efficient as a twin engine aircraft and doesn't offer as much scheduling flexibility.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing the 747 in 1969 to the A380 today isn't really a good comparison. A better comparison would be comparing both of them today. In 1969, the 747 was revolutionary. It was the first large jet that could get a lot of people from one side of the world to the other relatively quickly and efficiently (compared to the previous-generation 707, DC-8, etc.) At that time, having either 3 or 4 engines was &lt;em&gt;required by law&lt;/em&gt; for flights operating more than 60 minutes away from the nearest suitable diversionary field (in FAA-land, at least,) so it was a must for any aircraft that wanted to operate long-haul routes. However, &lt;a href=&quot;https://aviation.stackexchange.com/a/16516/755&quot;&gt;as my answer here discusses further&lt;/a&gt;, the introduction of &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;ETOPS&lt;/a&gt; in the 1980s and 1990s allowed twin-engine aircraft to start operating those routes. Since that time, the era of 3-engine and 4-engine airliners has been quickly drawing to a close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowadays, airlines can get the same number of passengers from point A to point B using less fuel on large twin-engine aircraft while also gaining the ability to offer more flexible schedules (by spreading those passengers out between multiple daily flights) and better ability to match the number of seats on a route to demand on the route. Additionally, less engines means less maintenance costs. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A340&quot; rel=&quot;nofollow noreferrer&quot;&gt;A340&lt;/a&gt; was the first major casualty of this effect, but it's killing the 747 and A380 programs, too. Meanwhile, Boeing and Airbus can't make 777s, 787s, A330s, or A350s as fast as they can sell them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's what Wikipedia currently lists for open orders on the above types:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4-engine airliners:&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8#Orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-8&lt;/a&gt;: 31 unfilled orders&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Airbus_A380_orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A380&lt;/a&gt;: 152 unfilled orders (which are mostly old and &lt;a href=&quot;http://www.bloomberg.com/news/articles/2014-07-30/airbus-profit-rises-10-as-aircraft-deliveries-increase&quot; rel=&quot;nofollow noreferrer&quot;&gt;some of which may be cancelled&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Twin-engine airliners:&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777#Orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 777&lt;/a&gt;: 563 unfilled orders&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Boeing_787_orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 787&lt;/a&gt;: 803 unfilled orders&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330#Orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A330&lt;/a&gt;: 176 unfilled orders (I can't tell if this is also including the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330neo#Orders&quot; rel=&quot;nofollow noreferrer&quot;&gt;145 A330neo orders&lt;/a&gt;)&lt;br&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Airbus_A350_XWB_orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A350&lt;/a&gt;: 776 unfilled orders.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/11519/755&quot;&gt;This answer&lt;/a&gt; to the question about &lt;a href=&quot;https://aviation.stackexchange.com/q/8715/755&quot;&gt;whether Airbus is planning to make a stretched A380&lt;/a&gt; also contains some relevant information.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-29T15:03:06.267" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="17379" PostTypeId="1" AcceptedAnswerId="17380" CreationDate="2015-07-29T14:24:50.267" Score="4" ViewCount="310" Body="&lt;p&gt;I hear about &lt;a href=&quot;https://en.wikipedia.org/wiki/Jessica_Cox&quot; rel=&quot;nofollow&quot;&gt;Jessica Cox&lt;/a&gt;; born without arms, she is the world's first licensed armless pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can you pilot a plane without arms? How are the controls modified in order to let her fly? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway: great respect for this woman. Absolutely. &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="5517" LastEditDate="2015-07-29T14:29:38.553" LastActivityDate="2015-07-29T14:33:53.550" Title="How can you fly a plane without arms?" Tags="&lt;pilots&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17380" PostTypeId="2" ParentId="17379" CreationDate="2015-07-29T14:33:53.550" Score="5" Body="&lt;p&gt;Jessica Cox explains it herself in this video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=b2IqpPSF9-U&quot; rel=&quot;noreferrer&quot;&gt;https://www.youtube.com/watch?v=b2IqpPSF9-U&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;She's using her legs in place of hands (I.e, using her feet to manipulate the controls, throttle etc) and she specifically flies an Ercoupe which has no rudder pedals.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-07-29T14:33:53.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17381" PostTypeId="1" AcceptedAnswerId="17389" CreationDate="2015-07-29T14:47:06.613" Score="3" ViewCount="1426" Body="&lt;p&gt;Many supersonic fighters have a &lt;a href=&quot;https://en.wikipedia.org/wiki/Stabilator&quot; rel=&quot;nofollow noreferrer&quot;&gt;stabilator&lt;/a&gt; to control pitch. My question arises when I cannot see any trim-tab on the stabilisator (e.g. on the &lt;a href=&quot;http://www.airliners.net/photo/Norway---Air/General-Dynamics-%28Fokker%29/2426899/&amp;amp;sid=c0ce83e7c6d9ee5c7702f85ea662750e&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt; or on the &lt;a href=&quot;http://www.airliners.net/photo/USA---Air/Lockheed-Martin-F-22A/1600536/&amp;amp;sid=b7eada1c827d3e194ac1b69cc4a6d942&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22&lt;/a&gt;). Other means to trim an aircraft without trim-tab and without using the &lt;a href=&quot;https://aviation.stackexchange.com/questions/15268/how-does-trim-work-on-an-a320&quot;&gt;stabiliser as a trim&lt;/a&gt; must exist. What are those means?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-07-29T17:38:41.073" Title="How is an aircraft with a stabilator trimmed?" Tags="&lt;trim&gt;&lt;trim-tab&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17382" PostTypeId="1" AcceptedAnswerId="17391" CreationDate="2015-07-29T15:03:28.080" Score="10" ViewCount="2828" Body="&lt;p&gt;All-moving flight control surface (stabilator instead of a stabilisator+elevator) &lt;a href=&quot;https://aviation.stackexchange.com/questions/16379/why-most-of-the-supersonic-or-fighter-aircraft-use-all-moving-control-surfaces&quot;&gt;are common on supersonic aircrafts&lt;/a&gt; but this is usually used for pitch control only. For rudder, this design (one all-moving piece instead of 2 separated pieces, the rear one being the one moving) is not common. The only example I think of is the &lt;a href=&quot;http://www.airliners.net/photo/USA---Air/Lockheed-SR-71A-Blackbird/1314199/&amp;amp;sid=685dfda480771ad19ca17f1c3f4e2e20&quot; rel=&quot;nofollow noreferrer&quot;&gt;SR-71&lt;/a&gt;. What are the reason for adopting this all-moving rudder on the SR-71? Why is it not spread? In short, what are the pros and cons of all moving control surface for yaw control?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-07-29T19:07:33.433" Title="What are the pros/cons of all-moving rudder?" Tags="&lt;flight-controls&gt;&lt;rudder&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17383" PostTypeId="2" ParentId="17354" CreationDate="2015-07-29T15:04:51.260" Score="4" Body="&lt;p&gt;The numbers are indeed chosen mostly for marketing. Although there is an element of logic and organization of models, as with other products, the name is primarily a marketing tool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787-8 emphasizes the number 8. &lt;a href=&quot;https://en.wikipedia.org/wiki/8_%28number%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;This number&lt;/a&gt; has positive connotations in some Asian cultures. Including the two most populous contries in the world, Asia represents a huge market that has been growing rapidly, and this means big opportunities for aircraft manufacturers. As discussed on &lt;a href=&quot;https://aviation.stackexchange.com/q/19151/1696&quot;&gt;another question&lt;/a&gt;, Airbus and Boeing are both looking to gain orders from this growing market. The launch customer for the 787-8 was a Japanese airline, ANA. &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Boeing_787_orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Almost a quarter of 787 orders&lt;/a&gt; have come directly from airlines in Asia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting with 8 also makes the type seem more established than starting back with -1 or -100, and allows the 747-8 to share the same number to connect the technology shared between the two, mostly in the engines and wings. The 747 connection to Asia is even more apparent than with the 787. Airlines in Asia represent a large portion of past 747 deliveries, which provides an opportunity for them to upgrade to the newest version. Although the launch customers for both cargo and passenger versions are European, &lt;a href=&quot;http://www.usatoday.com/story/todayinthesky/2014/09/30/air-china-becomes-second-airline-to-get-a-boeing-747-8i/16472829/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Asian customers&lt;/a&gt; represent &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;almost half of the orders&lt;/a&gt;. Using a single number also differentiates their models from &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus&quot; rel=&quot;nofollow noreferrer&quot;&gt;the competition&lt;/a&gt;, but also seems to have confused &lt;a href=&quot;http://avherald.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;some people&lt;/a&gt; that are used to the old convention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting with the 707, Boeing planes started with the -100 and added variants from there. This includes the 727, 737, and 747 as well. The 757 started with the -200 model because this corresponded to the approximate capacity of the 727-200 model it was replacing, which is where they saw the most demand. The 767 started with -100, but this model was never offered, being too close to the 757, so the 767 also starts with -200. The 777 is a similar situation, where a -100 was considered but never offered. The 737 has now run out of numbers, and rather than go up to -10 like the 787 or -1000 like the A350, they chose to go with -7 through -9. This matches the scheme of the other newer models while also relating to the corresponding NG versions of -700 through -900.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 is in a slightly different situation, skipping both type and model numbers to start at A380-800. Although by far the most orders are from &lt;a href=&quot;https://en.wikipedia.org/wiki/Emirates_(airline)&quot; rel=&quot;nofollow noreferrer&quot;&gt;one particular airline&lt;/a&gt;, customers in Asia still represent &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Airbus_A380_orders_and_deliveries&quot; rel=&quot;nofollow noreferrer&quot;&gt;almost 20% of the orders&lt;/a&gt;. Asia would seem to represent a prime market for a large airplane, with both high traffic routes and long international routes, but like the 747-8 &lt;a href=&quot;https://aviation.stackexchange.com/q/17374/1696&quot;&gt;the A380 has not received as many orders as expected&lt;/a&gt;. While it's unlikely that either Airbus or Boeing will disclose details of their marketing strategies, it's clear that the number 8 is a positive number in many Asian countries, both manufacturers have chosen to emphasize the number on all of their newest models, and the region represents a very important market for these aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-09T15:29:07.537" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17384" PostTypeId="1" AcceptedAnswerId="17386" CreationDate="2015-07-29T15:38:14.037" Score="3" ViewCount="986" Body="&lt;p&gt;I just read &lt;a href=&quot;https://aviation.stackexchange.com/questions/15710/is-the-emergency-fluorescent-floor-lighting-strip-along-the-aisle-an-item-on-the&quot;&gt;this question&lt;/a&gt; (about emergency lighting) for which nobody highlight the title mention &lt;a href=&quot;https://en.wikipedia.org/wiki/Fluorescence&quot; rel=&quot;nofollow noreferrer&quot;&gt;fluorecence&lt;/a&gt;. As this &lt;a href=&quot;http://www.skybrary.aero/index.php/Emergency_Floor_Lighting&quot; rel=&quot;nofollow noreferrer&quot;&gt;lighting's requirements&lt;/a&gt; include operability with failure of normal electrical power, having fluorescent strip doubling a ramp of lights make sense. However, the pictures illustrating the answers shows seat-mounted lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question focus on the emergency floor lighting installed on the floor. Do this kind of emergency lighting use fluorecent elements?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-31T14:51:14.383" Title="Is emergency floor lighting fluorescent?" Tags="&lt;emergency&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17385" PostTypeId="2" ParentId="16389" CreationDate="2015-07-29T16:00:54.883" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.uavcropdustersprayers.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;These guys&lt;/a&gt; seem to offer some products in that space however it seems many of them are of the remote control variant (not fully automated). Crop dusting is a pretty routine task and you could easily program a drone to cover a specific field at a given time and let it do its thing. The main issue you will face in the current market is simply useful load. Ignoring the military drones out there most of the commercially available unmanned vehicles are on the smaller side and simply don't have the useful load of something like a Piper Pawnee that is used for current crop dusting.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does seem that the &lt;a href=&quot;http://www.faa.gov/uas/legislative_programs/section_333/333_authorizations/media/Yamaha_11448.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA has approved&lt;/a&gt; some &lt;a href=&quot;http://www.bloomberg.com/news/articles/2015-05-05/yamaha-drone-helicopter-approved-for-farm-flights-by-u-s-faa&quot; rel=&quot;nofollow noreferrer&quot;&gt;drones&lt;/a&gt; for this use but that was recently so Im sure it will be a little while before we see them. Although it seems Japan has been using them for this purpose for some time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes tank carrying drones do exist (but I cant find the volume of the tanks, they do however appear pretty small). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/14zbk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/14zbk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FWIW any small drone could be modified to carry a tank and spraying device provided it could lift it. All things considered people have built some &lt;a href=&quot;http://sploid.gizmodo.com/these-awesome-rc-airplanes-are-so-huge-that-you-can-fly-1644851216&quot; rel=&quot;nofollow noreferrer&quot;&gt;pretty big&lt;/a&gt; RC planes&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-07-29T16:00:54.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17386" PostTypeId="2" ParentId="17384" CreationDate="2015-07-29T16:04:25.510" Score="8" Body="&lt;p&gt;Fluorescent (more specifically phosphorescent as the re-emission of absorbed light happens on a longer time scale) plastics are sometimes used for exit indicators as they're better than nothing when every other system fails, however they have some drawbacks that limit their usefulness, and so they're not relied on as a primary source of emergency illumination in aviation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;They're not very bright.&lt;/strong&gt; Even a battery-backup 5-watt incandescent provides more light, and when passengers are trying to find the exit through a cloud of smoke from an engine fire, bright saves lives.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;They lose brightness quickly.&lt;/strong&gt; Here are samples of zinc sulfide on the left and strontium aluminate on the right of each picture. The first picture is immediately after the light source goes out. The second is after just four minutes of darkness:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z2dYl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z2dYl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gUCE2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gUCE2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;They rely on external light sources illuminating them for a minimum time.&lt;/strong&gt; On night flights (when luminescent exit indicators would be most needed), the cabin lights are often dimmed, reducing the effectiveness of photoluminescent strips. Passenger garments overlapping the strips, such as skirts or waist-tied jackets, will have a similar effect on individual strips.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Most pigments react most strongly to UV light which is undesirable for most other purposes.&lt;/strong&gt; UV light is invisible to us so it's wasted energy, and it yellows plastics (such as cabin trim) which ages airliner cabins more quickly. Light sources that minimize UV are preferable for any purpose except for &quot;charging&quot; photoluminescent strips.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;They can't be turned off.&lt;/strong&gt; When cabin lights are dimmed for passenger comfort on a night flight (letting people sleep etc), the photoluminescent strips will make the cabin look like a cheap Halloween party for up to ten minutes after.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, there are better options, especially now with white LEDs that are more efficient and less of a fire hazard than incandescent lights. A simple lithium button battery in the same assembly as the light could keep a 50-lumen LED array going more than long enough even in a complete electrical failure, and LEDs bright enough for this purpose are becoming ridiculously cheap thanks to advances in LED lighting for homes and businesses.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-07-31T14:51:14.383" LastActivityDate="2015-07-31T14:51:14.383" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17387" PostTypeId="2" ParentId="17381" CreationDate="2015-07-29T16:04:43.277" Score="3" Body="&lt;p&gt;Pitch trim on an aircraft with a stabilator is normally accomplished by moving the entire stabilator and holding it in its new trimmed position either mechanically (using the same mechanism as normal pitch control),  aerodynamically (using an &quot;anti-servo tab&quot;), or some combination of the two.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept is similar to stabilizer trim as discussed in the other question, only instead of moving the &quot;fixed&quot; forward part of the horizontal stabilizer the entire control surface is moved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; has a good illustration of an anti-servo tab:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/bClAh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bClAh.png&quot; alt=&quot;PHAK - Anti-Servo Tab&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-29T16:04:43.277" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17388" PostTypeId="2" ParentId="17382" CreationDate="2015-07-29T16:53:43.073" Score="4" Body="&lt;p&gt;Pros:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Higher rudder sensitivity; moving the entire vertical stabilizer increases the surface area redirecting airflow, allowing higher yaw rates using rudder only.&lt;/li&gt;&#xA;&lt;li&gt;Better performance at low airspeeds, for much the same reason.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Increased forces on the vertical stabilizer at higher speeds, possibly in excess of materials strength; requires a limiter system such as FBW to account for airspeed and reduce stabilizer rotation at higher speed to produce a constant yaw force for a given rudder pedal input and to prevent overstress.&lt;/li&gt;&#xA;&lt;li&gt;Increased interference drag. Interference drag occurs when aerodynamic surfaces meet at perpendicular angles; air being moved in one direction encounters air being moved perpendicularly at the same time, causing energy to be spent compressing the air. All-moving control surfaces typically preclude the use of fairings to reduce this phenomenon.&lt;/li&gt;&#xA;&lt;li&gt;Causes more of a roll moment in the direction opposite the yaw. Stabilators on fighters are also often used as &quot;elevons&quot;, producing roll as well as pitch control. A vertical all-moving surface in the same configuration as an ordinary tail would provide an unbalanced force on the top of the airframe to roll the aircraft in the opposite direction to the yaw, only magnified by the increased surface area redirecting airflow. You could correct this with an equal or at least offsetting vertical all-moving surface below the empennage.&lt;/li&gt;&#xA;&lt;li&gt;Interference with horizontal stabilators. Traditional elevators/rudder are easier to keep out of each others' way, but when the entire stabilizer rotates, this becomes more difficult. Typically pitch is emphasized over yaw, and so an all-moving vertical stabilizer would be limited in total travel even at low speed to prevent binding the horizontal stabilator. You could stagger horizontal and vertical surfaces but that reduces the moment arm that the closer one has, offsetting the gains of an all-moving surface.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other reasons it's not used when stabilators are include the fact that emphasis in aerobatic airframe design is typically on maximizing pitch and roll. Rudder is typically used to augment yaw produced by bank in a coordinated turn and so the amount of force the rudder provides is of least overall importance compared to the other primary control surfaces.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-29T16:53:43.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17389" PostTypeId="2" ParentId="17381" CreationDate="2015-07-29T17:05:09.913" Score="4" Body="&lt;p&gt;Trim is simply a force that offsets the neutral position of the control surface. On aircraft with mechanical controls it is provided aerodynamically via trim tab, but it can also be provided by springs, hydraulics, or simply by adding the selected offset in the fly-by-wire computer. Since F-16, F-18 and F-22 are all fly-by-wire, the last option is most likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, all these fighters are aerodynamically &lt;em&gt;unstable&lt;/em&gt;, which requires using “cooked” controls where centred stick commands the computer to maintain straight flight and the computer then adjusts the stabilators accordingly, doing small corrections all the time since the flight path would quickly diverge without that. So there is no trim in the traditional sense at all.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-07-29T17:05:09.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17390" PostTypeId="2" ParentId="11814" CreationDate="2015-07-29T17:35:29.523" Score="1" Body="&lt;p&gt;Yes, recently &lt;a href=&quot;http://www.planeflighttracker.com/2014/03/military-aircraft-tracker.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;PlaneFlightTracker&lt;/a&gt; provided exactly this live service both for NATO and Russian Military aircraft as well as &lt;a href=&quot;http://www.planeflighttracker.com/2014/12/emergency-medical-air-services-search.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Medical, Emergency, Safe and Rescue&lt;/a&gt; helicopters and airplanes. It starts with a procedure explaning how to track as well as Live Military Aircraft Maps. This site uses the FlightRadar24 map for embedment but has made an effort to extract necessary ICAO codes so that the users may get the proper maps.&lt;/p&gt;&#xA;" OwnerUserId="9578" LastEditorUserId="7532" LastEditDate="2020-11-21T04:22:10.073" LastActivityDate="2020-11-21T04:22:10.073" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17391" PostTypeId="2" ParentId="17382" CreationDate="2015-07-29T18:49:54.967" Score="6" Body="&lt;p&gt;All-moving control surfaces are like regular surfaces, only that the moveable part extends over 100% of the chord. Since the effectivity of a control surface grows with the square root of the chord fraction $\lambda$ of its moveable part, an all-moving (also called full-flying) control surface has twice the effectivity (defined as normal force change per degree of movement) of one with a 25% chord length of its moveable part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0k9P2.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0k9P2.png&quot; alt=&quot;Control effectivity over chord&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effectivity of a control surface over chord fraction $\lambda$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Hermann_Glauert&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hermann Glauert&lt;/a&gt; was the first to calculate the inviscid lift due to control deflection, and the result of his work is shown above. The truth (as defined by wind tunnel results) is somewhere between his curve and that of my simple approximation.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Control surface in subsonic flow&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Deflecting a flap causes the camber of the control surface to change. This is a positive effect in subsonic flow and allows the resulting airfoil to create more lift in the desired direction. Also, the orientation of the leading edge is maintained, causing much smaller suction peaks there than when the full surface is deflected. Suction peaks require a long pressure rise, which promotes &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; when its gradient is too steep.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Control surface in supersonic flow&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In supersonic flow, camber increases wave drag, so the full-flying control surface is more effective. Pure supersonic flow has no suction peaks, and flow separation is less of a concern. Therefore, full-flying surfaces are better for supersonic flight, while hinged surfaces are the better choice in subsonic flow. Especially in transsonic flow, at least a moveable stabilizer is necessary to &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight&quot;&gt;avoid control reversal&lt;/a&gt; due to the contour break of a hinged control surface.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Stealth aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Stealth aircraft benefit from large, coherent surfaces, and the gap of a control hinge will increase their &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar_cross-section&quot; rel=&quot;nofollow noreferrer&quot;&gt;RCS&lt;/a&gt;. Even subsonic stealth aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-117_Nighthawk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-117&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Tacit_Blue&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop Tacit Blue&lt;/a&gt; use full-flying control surfaces for their &lt;a href=&quot;https://aviation.stackexchange.com/questions/3741/how-do-the-beech-bonanzas-ruddervators-work&quot;&gt;ruddervators&lt;/a&gt;, as does the supersonic &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop YF-23&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why the SR-71 rudders are special&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An &lt;a href=&quot;https://en.wikipedia.org/wiki/Unstart&quot; rel=&quot;nofollow noreferrer&quot;&gt;intake unstart&lt;/a&gt; at Mach 3.2 is a violent event, and the SR-71 needed all the yaw control authority available to compensate for the sudden asymmetric loss of thrust. Its rudders were optimized for supersonic use, and the actuator could be driven to its extreme position by an explosive charge which was fired automatically when an intake unstart was detected. To ensure optimum intake operation, the engines were positioned at mid-span, and the yawing moment of thrust changes was much higher than that of conventional fighter aircraft which have their engines close to the centerline for better roll agility. In addition, they use their rudders mostly in subsonic flight; only the size of the vertical tail is determined by yaw stability at top speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-07-29T19:07:33.433" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17392" PostTypeId="2" ParentId="17374" CreationDate="2015-07-29T19:21:06.657" Score="74" Body="&lt;p&gt;Several reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;A380s are &lt;em&gt;really&lt;/em&gt; expensive.&lt;/strong&gt; Unit cost for an A380, depending on interior appointments, is about \$375 million. The 747-8 is about \$357 million. The 777-300ER is about \$320 million, the last variants of the A340 about \$275 million, and the 787 about \$200 million. The 380 might be the biggest airliner ever to fly, but it's also the most expensive. Keep in mind these jets can't fly every day, requiring you to buy a couple more than the schedule requires and rotate them in as maintenance is required on each airframe. That means A380 operators have at least one three hundred and eighty million dollar airframe sitting on the tarmac not making money on any given day (in fact, up to 55 days at a time for the 6-year &quot;D check&quot; maintenance, not counting lower-level maintenance performed more often as well as any unscheduled maintenance).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Airbus could not/cannot build them fast enough to meet initial orders in a timely manner.&lt;/strong&gt; Airbus received 189 initial A380 orders prior to the airframe's scheduled start of production in 2007, plus 27 A380F variant orders, and has received 128 since production began (though the freighter orders were cancelled). To date, it's only delivered about half due to a combination of issues found during full-scale production that delayed ramp-up, and currently its pace is about 30 planes a year, giving it about a 3 year backlog of remaining orders (some of which have been sitting in the build queue for 10 years). It initially prioritized passenger variants for Emirates, which put in the largest single order (almost half of total orders) to handle that airline's primarily long-haul schedule. As a result, everyone else got pushed off until many (including FedEx and UPS which were waiting for freight versions) cancelled their orders and went to Boeing for 747-8Fs or 777-ERFs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Jumbos represent a serious cost-revenue risk that most airlines are no longer willing to gamble on.&lt;/strong&gt; You use a jumbo jet when you need to move a lot of people at one time. That typically means a high-demand, long-distance route that calls for nonstop service, but that you don't want to have to fly any more times than you have to. 747s used to be used for high-volume domestic connectors in the US during and immediately after the regulation era, between major cities like New York, Chicago, LA, Houston, Miami etc. They were also used for major intercontinental flights, primarily because regulations required more than two engines for trips extending a certain distance beyond the nearest divert field. However, the 747 is a 50-year-old design with only incremental improvements made in efficiency. Four engine jets in the modern air transport market require you to fill the plane every time, and with ETOPS-rated two-engine widebodies now making many of the same flights that previously required three or more engines, the A380, even with the most efficient engines ever put on a commercial airliner, is at least three decades late to the jumbo party, and is entering the market at a time when the 747 is being phased out of most fleets in favor of more economical widebodies.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The A380 was designed for an air travel market that hasn't materialized.&lt;/strong&gt; Airbus was betting big (NPI) on airport congestion and increased passenger counts during the 80s and 90s requiring a shift to fewer flights on larger-capacity planes to reduce pattern and gate congestion. Except for a few major metropolitan areas that simply cannot grow their airports anymore (O'Hare, LaGuardia/JFK, Heathrow etc) that hasn't really been the case. 9/11 and the 2008 financial crisis have seen passenger counts plummet from post-regulation highs, which has reduced total flights and allowed smaller planes which are more efficiently scheduled. In addition, Denver opened up the largest airport by land area in the world (so it has plenty of room to grow), while Atlanta, Dallas, Charles de Galle and others are busy primarily because they're massive complexes with efficient layouts that can support a major airline's hub operations. The use of jumbos in general is therefore very risky, and many airlines, in addition to passing on the A380, are phasing out the venerable 747 that was previously unchallenged in this class, in favor of something a little more economical in the next smaller widebody class, like the 777, 787, A340 or A350. That was Boeing's bet, that smaller, high-efficiency jets would be the wave of the future over pure size, and it seems to be paying off as Boeing, despite higher production capacities, has more 787 orders than it has capacity for the foreseeable future, while Airbus's competing A350 is more or less getting the overflow (and it can't even meet that demand; 700 orders, 5 produced).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The A380 really doesn't solve the problem it was created for, and in fact causes more problems for airports than it solves.&lt;/strong&gt; A super-heavy like the A380 creates monumental wake turbulence that poses a danger to other planes, which requires ATC to space following traffic further back (up to double the time/distance compared to a midbody), while for smaller jets (even widebodies), approach control can usually get away with a little more than standard 2-minute spacing unless the plane behind it is a much smaller regional jet or GA prop. So, the A380 can carry about 520 passengers in mixed-class configuration (Emirates' 6-star config seating only about 490), but takes up two &quot;slots&quot; in the approach pattern, while a 777 can carry 320 passengers in mixed-class layout and can be spaced much more closely to other airliners. So in terms of maximizing total passenger movement at an airport, two 777s or A340s are better than one A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the gate, the A380 causes even more headaches. It's so honkin' &lt;em&gt;big&lt;/em&gt; that adjacent gates typically can't be used while it's parked, and it often requires additional jetways to efficiently board and deplane its passengers. As one example, DFW's Terminal D was fairly recently renovated to be the airport's primary international terminal, including Gate 16 in the southwest corner specifically intended to allow 747s to park with minimal adjacent gate disruption (17 couldn't be used, but 18 was available for smaller jets and 15 around the corner could handle pretty much any size):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8OldV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8OldV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the A380 came to DFW in 2014, with Qantas replacing the 747 on the famous Flight 7 and Flight 8 from Sydney to DFW (the longest scheduled passenger flights by travel time in the world), and Emirates commencing service to and from Dubai with A380s, DFW had to redesign this corner of the airport entirely, basically having the A380 come in diagonally to Gate 15. Gate 15 then services first class, 16's jetway was moved and extended to load and unload the lower deck, and a third jetway, 16X, was built adjacent to 16 solely for the A380's upper deck. The jetways for Gates 14 and 17 then had to be lengthened considerably to allow their use with a 380 at the ramp, otherwise the superjumbo would essentially take up 4 entire gates while parked:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.uta.edu/engineering/_images_2015/events/4903863_G.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://www.uta.edu/engineering/_images_2015/events/4903863_G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/kMkfF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kMkfF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside for scale in the last image, Gate 14 to the right is in Sun Country livery which would make it a 737-700, while the American jet at the very top at Gate 19 is still in older livery, and with its long narrow body the best guess is a 757-200. Gate 17 looks like an Air Canada Rouge so with the body length I'd say A319, and Gate 18 is in new American livery so it's a 737-700. None of them really big aircraft by today's commercial standards, but they're certainly not puddle-jumpers either (all aircraft at this terminal are for international flights), and the Emirates A380 at gates 15/16/16X absolutely eclipses them all. It is a &lt;em&gt;big&lt;/em&gt; jet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.417" LastActivityDate="2015-10-09T17:56:00.543" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="17393" PostTypeId="2" ParentId="17340" CreationDate="2015-07-29T20:08:31.563" Score="4" Body="&lt;p&gt;A business reason no-one has mentioned yet is the original reason the big names started: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because low cost airlines began flying routes cheaply and created a market&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the big names hadn't joined in, all that revenue would have gone to the low cost airlines, who would have grown to the point they could potentially compete in the existing markets, so it was essential that the big players joined in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not possible to run a low cost airline in the structures of a major airline (the cost model is entirely different - passenger demographics, services on board, pre-flight hospitality, additional benefits etc.) so the only way to do it that makes financial sense is to run it as a separate logical entity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has proven to be a difficult change for some of those big airlines, with various attempts at creating budget versions failing, but some have managed to compete successfully.&lt;/p&gt;&#xA;" OwnerUserId="59" LastEditorUserId="59" LastEditDate="2015-07-29T20:23:32.553" LastActivityDate="2015-07-29T20:23:32.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17394" PostTypeId="2" ParentId="17272" CreationDate="2015-07-29T20:15:26.307" Score="4" Body="&lt;p&gt;The certificate number is not personal information unless it is SSN based, in that case the person should request a new number.  This would mitigate the value of the certificate number for the purpose of committing a fraud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it provides no further leap to further personal information or access to government systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would continue to show due care with personal information and think about to who you provide anything too, always ask why.  As for your certificate, it is far less invasive to provide this than a copy of your drivers license.  I wouldn't fret on this particular document since is not a key to any service.&lt;/p&gt;&#xA;" OwnerUserId="8375" LastActivityDate="2015-07-29T20:15:26.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17395" PostTypeId="2" ParentId="17376" CreationDate="2015-07-29T22:17:21.337" Score="4" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Jumbos and widebodies are harder to fly than amateur pilots often think.&lt;/strong&gt; The larger and more complex the aircraft, the further ahead in time the pilot has to be thinking in order to get the plane where he wants it in the configuration he wants it. This increases pilot workload even when &amp;quot;just cruising&amp;quot;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;There is a natural progression from smaller to larger planes and fewer to more passengers through all levels of pilot training and certification&lt;/strong&gt;. You don't put a student pilot in an A380 with 500 passengers aboard for their first solo flight. You give them an LSA costing $25-50k and don't allow them to carry any passenger besides their instructor. As the pilot gains skill and experience, they transition to larger and more powerful aircraft and gain more privileges and responsibilities. Parallels abound; knowing how to drive a 19-foot speedboat on a lake is no qualification to be at the helm of the Carnival Magic, or the U.S.S. Ronald Reagan. Knowing how to drive a go-cart in a parking lot is no qualification to be behind the wheel of a road train.&lt;/p&gt;&#xA;&lt;p&gt;Case in point, someone who just got their ATPL/AMEL likely has had zero stick time in an actual airliner; they're simply too big and expensive to run for flight schools to be using them for flight training. What they've probably logged actual flight time in for an AMEL category rating is closer to a Gulfstream or Learjet; a high-performance narrow-body T-tail. That's not really going to cut it for a 737, but that experience transfers pretty seamlessly to a regional narrow-body airliner like a Bombardier or Embraer; slightly bigger and heavier but not totally out of the ballpark in configuration and performance envelope. Establish a good track record in those and you work your way to the 100-seaters like the E195, and from there you can continue to work your way up as your experience and mentality allow you to handle the longer lead times and increased complexities of bigger jets.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Smaller flights tend to bring in less revenue and lower margins, primarily due to increased competition on those routes&lt;/strong&gt;. Yes, the seats turn over more quickly as the smaller jets make shorter hops, but do the math; DFW-PHX costs about \$320 a seat, you have about 130 seats on a 737 or A320 running that route, and you can run it about 3 flights between those two airports gate-to-gate in 10 hours. Total revenue, somewhere in the ballpark of \$125,000 a day. A ticket from DFW to LHR costs about \$2200, it's run with a 777-300ER which carries about 320 people per flight, and you run that once in the same 10 hours. Total revenue for a full flight, about \$700,000. Even given that the DFW-LHR flight will probably require two crews and the fuel costs per passenger mile will be higher, you're still making more money off the larger plane, &lt;em&gt;provided&lt;/em&gt; you can fill it.&lt;/p&gt;&#xA;&lt;p&gt;Now, this very same cost breakdown doesn't seem to hold at first for a smaller regional jet. Waco to DFW is an hour gate-to-gate and costs ~\$325 a ticket. In the same ten-hour flight time of the DFW-LHR flight, a 50-seat ERJ145 could theoretically bank up to \$162,500, more than the DFW-PHX flight. But, nobody's paying \$325 to fly from Waco to DFW unless they're &amp;quot;stupid rich&amp;quot;; you can drive between those cities in an hour and a half for the cost of about 5 gallons of gas, and people know that. They also know that if they're going to DFW to catch another flight for a week or ten-day trip, the parking fees will eat them alive. A more realistic scenario is ACT-PHX via DFW. That ticket costs \$360. Recall that DFW-PHX by itself was \$320, so your passengers are paying more like \$40/seat for the regional connector, and at that rate 10 trips with a 50-place jet would bring in a scant \$20,000/day, which might barely break even on fuel and fees to operate that route.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Older pilots want more pay.&lt;/strong&gt; As in many industries, workers expect their experience to count for something on their pay stubs. From simple cost-of-living raises to the money needed to raise a family and eventually retire, airline senior captains often end their careers in the low to mid six figures. They also start lower on the pay scale and so get less of a head start building a home and retirement; regional jet operators start around $22,000 which is just above poverty line (which is part of the complaint; a pilot's starting salary is not a living wage especially considering what it takes just to be able to apply for the job). Given the costs of flight training, and the starting salaries of other skilled trades, learning to fly for a living is not the obvious choice. So the ones that stick with it and work their way to senior captain expect to make up the difference at the end of their careers.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Given all of these points, it makes sense to put junior pilots making less money in smaller airliners, and increase the airframe size and the pay as a pilot advances through their career.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-07-30T16:24:20.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17396" PostTypeId="1" AcceptedAnswerId="17402" CreationDate="2015-07-29T23:21:37.960" Score="10" ViewCount="1583" Body="&lt;p&gt;Looking up numbers for &lt;a href=&quot;https://aviation.stackexchange.com/a/17392/7629&quot;&gt;my answer to the A380 production question&lt;/a&gt;, it occurs to me that Airbus is facing a real inability to deliver its latest airframes. The A380 is currently sustaining a build pace of 45 aircraft a year with a backlog of about 150 outstanding orders. The A350, Airbus's direct competitor to the 787, has better orders (781 outstanding), but Airbus has been able to deliver only 5 of those, 4 to Qatar Airways and 1 to AerCap. The A340 ended production in 2011, so the 330 (1370 orders, backlog of 356)  350 and 380  are Airbus's only three widebodies in production right now. The 320 and 321 are backlogged badly, though Boeing has a similar backlog for 737 variants so that seems par for the course in the modern aviation industry dominated by LCCs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has had fewer orders for its 747-8 but is keeping pace (92 delivered of 123 ordered, averaging 18 airframes a year) and has an embarrassment of riches in 787 orders (1095 ordered, 295 delivered, on pace for about 115 aircraft a year after ramp-up) and healthy business with the older 777 (backlog of 560, in the ballpark of about 80 deliveries a year since 2010). Its 767 frame, a close competitor to the A330, has slightly fewer orders despite being the older plane, but Boeing seems to be keeping pace (less than 100 backlogged in a total of 1161 orders).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read these numbers and I come to the conclusion that Airbus is in big trouble in the large and very large jet markets it was planning to dominate just ten years ago; Boeing, by most accounts seems to be out-producing them and thus getting the lion's share of a mostly post-jumbo market. Am I reading this right?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-12T17:49:18.917" Title="Does Airbus have a production problem?" Tags="&lt;airbus&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17397" PostTypeId="2" ParentId="11814" CreationDate="2015-07-30T02:33:09.387" Score="6" Body="&lt;p&gt;Flight-tracking sites &lt;em&gt;can&lt;/em&gt; track military aircraft, but generally &lt;em&gt;don't&lt;/em&gt;.  For example, I live near a USAF base and can easily track dozens of military flights a day with an ADS-B receiver, but not one of those flights has ever shown up on FlightRadar24. &lt;/p&gt;&#xA;" OwnerUserId="1677" LastActivityDate="2015-07-30T02:33:09.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17398" PostTypeId="2" ParentId="17155" CreationDate="2015-07-30T02:47:56.143" Score="2" Body="&lt;p&gt;With respect to &quot;centering&quot;, a yoke only &quot;centers&quot; itself in the equilibrium point where forces on both ailerons and on both top and bottom of the elevator/stabilator are equal. That said, I wouldn't want to let the yoke &quot;center and fly itself&quot; as the forces on the control surfaces can be equal even when the aircraft is not straight and level. If not enough power is applied the plane will pitch down and &quot;center&quot; as you say, and if too much power is applied the plane will pitch up and then &quot;center&quot;. As for roll, I find that in light aircraft (Cirrus excluded as the side stick has a spring mechanism) you don't usually want to leave the yoke out of hand as slight wind and light wind shear will cause the airplane to roll somewhat. So - short answer is - yes, it will &quot;center&quot; eventually but you might not like the attitude the plane is in when it's done, much of this depending on power setting and gusts/shear aloft/turbulence. As for autopilot, a roll and pitch (2-axis) autopilot actually continually applies force to the controls to keep the airplane level or turning as commanded, and at a constant altitude or climb/descent/airspeed as commanded, so I wouldn't say the controls really &quot;center&quot; when on autopilot either. Cheers!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bit more of an explanation, a &quot;nice&quot; airplane (one with positive aerodynamic stability) with the appropriate power setting should re-enter and maintain straight and level flight if the controls are disturbed and the yoke is released (but I've always had to input a little roll to keep the wings level). Check out the following picture from the FAA Pilot's Handbook of Aeronautical Knowledge Page 4-14: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g0Olf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g0Olf.png&quot; alt=&quot;PHAK 4-14&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that the orange line eventually gets more and more flat. You can expect that in a Cessna 172 or something of the like... not in a more aggressive plan like aerobatic planes and fighter jets - you'll see something a little more like the green or red line. You can read more in Chapter 4 of the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA PHAK (link here)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2015-07-30T02:59:06.317" LastActivityDate="2015-07-30T02:59:06.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17399" PostTypeId="1" AcceptedAnswerId="17401" CreationDate="2015-07-30T04:03:32.343" Score="32" ViewCount="10912" Body="&lt;p&gt;I've only seen the snowflake symbol with temperature listed on this one approach plate for KASE airport in Aspen, CO. I looked for it in the legend but didn't find it. Does anyone know what the snowflake symbol with temperature means?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/mglHACV.png&quot; alt=&quot;appr plate&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="7532" LastEditDate="2015-08-01T12:25:48.400" LastActivityDate="2015-08-01T12:25:48.400" Title="What does the snowflake with temperature symbol on an approach plate mean?" Tags="&lt;approach&gt;&lt;aeronautical-charts&gt;&lt;terps&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17400" PostTypeId="2" ParentId="17399" CreationDate="2015-07-30T05:11:41.380" Score="11" Body="&lt;p&gt;It indicates a &quot;temperature restricted&quot; airport where precautions are required to calculate and set correct altimeter settings because the errors caused when the temperature is at the lowest recorded , if not corrected, can exceed the required obstacle clearance shown on the chart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the air is significantly more dense than the &quot;ISA standard day&quot;, the altimeter can over read (the pressure for a given altitude will be greater), telling you that you are higher than you really are with a risk of ground or obstacle collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the temperature is at or below that shown on the chart, altitude corrections must be made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/notices/media/3-05-15_NTAP.pdf&quot;&gt;Full details can be found at 4-GEN-14 of the FAA NOTAMs&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-07-30T05:11:41.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17401" PostTypeId="2" ParentId="17399" CreationDate="2015-07-30T05:29:48.340" Score="32" Body="&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2015/InFO15002.pdf&quot;&gt;FAA INFO 15002&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A [snowflake] -XX°C icon will be incrementally added to airport approach plates, beginning Mar 5, 2015. The&#xA;  icon indicates a cold temperature altitude correction will be required on an approach when the reported&#xA;  temperature is, “at or below” the temperature specified for that airport. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This looks to be a work-in-progress, as they started adding the icons in March, and compliance with applying the cold temperature altitude corrections becomes mandatory in September, 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More info from the &lt;a href=&quot;http://www.nbaa.org/ops/airspace/FAA-Cold-Temp-Restricted-Airports-20141211.pdf&quot;&gt;NBAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; In response to aviation industry concerns over cold weather altimetry errors, the FAA&#xA;  conducted a risk analysis to determine if current 14 CFR Part 97 instrument approach procedures, in the&#xA;  United States National Airspace System, place aircraft at risk during cold temperature operations. This study&#xA;  applied the coldest recorded temperature at the given airports in the last five years and specifically determined&#xA;  if there was a probability that during these non-standard day operations, anticipated altitude errors in a&#xA;  barometric altimetry system could exceed the Required Obstacle Clearance (ROC) used on procedure&#xA;  segment altitudes. If a probability, of the ROC being exceeded, went above one percent on a segment of the&#xA;  approach, a temperature restriction was applied to that segment. In addition to the low probability that these&#xA;  procedures will be required, the probability of the ROC being exceeded precisely at an obstacle position is&#xA;  extremely low, providing an even greater safety margin.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Action:&lt;/strong&gt;&#xA;  Pilots must make an altitude correction to the published, “at”, “at or above” and “at or below” altitudes on&#xA;  designated segment(s) (see list below), on all published procedures and runways, when the reported airport&#xA;  temperature is at or below the published airport cold temperature restriction. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pilots &lt;strong&gt;&lt;em&gt;without&lt;/em&gt;&lt;/strong&gt; temperature compensating aircraft are responsible to calculate and make a manual cold&#xA;  temperature altitude correction to the designated segment(s) of the approach using the AIM 7-2-3, ICAO Cold&#xA;  Temperature Error Table.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pilots &lt;strong&gt;&lt;em&gt;with&lt;/em&gt;&lt;/strong&gt; temperature compensating aircraft must ensure the system is on and operating for each segment&#xA;  requiring an altitude correction. Pilots must ensure they are flying at corrected altitude. If the system is not&#xA;  operating, the pilot is responsible to calculate and apply a manual cold weather altitude correction using the&#xA;  AIM 7-2-3 ICAO Cold Temperature Error Table. PILOTS SHOULD NOT MAKE AN ALTIMETER&#xA;  CHANGE to accomplish an altitude correction.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pilots must use the corrected MDA or DA/DH as the minimum for an approach. Pilots must meet the&#xA;  requirements in 14 CFR Part 91.175 in order to operate below the corrected MDA or DA/DH. Pilots must&#xA;  see and avoid obstacles when descending below the MDA.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The temperature restriction at a “Cold Temperature Restricted Airport” is mutually exclusive from the charted&#xA;  temperature restriction published for “uncompensated baro-VNAV systems” on 14 CFR Part 97 RNAV&#xA;  (GPS) and RNAV (RNP) approach plates. The charted temperature restriction for uncompensated&#xA;  baro-VNAV systems is applicable to the final segment LNAV/VNAV minima. The charted temperature&#xA;  restriction must be followed regardless of the cold temperature restricted airport temperature.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's more info in the NBAA document (I only included the exciting parts), including a list of affected airports, listed by state.  Lots in Alaska, none in Florida, unsurprisingly.  Applying this in flight looks like an absolute can of worms, as far as I can tell from the examples presented.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We'll probably see more come out about this as cold weather approaches, so stay tuned!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-07-30T05:29:48.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17402" PostTypeId="2" ParentId="17396" CreationDate="2015-07-30T08:38:32.503" Score="19" Body="&lt;p&gt;A backlog of orders does not indicate a manufacturing problem. Quite opposite, it is good for the business as it adds stability. Airbus outpaced Boeing on every aircraft expect the A350/787 last year. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Producing all of the backlog in one year is not a good idea, as investments into the production line would be enormous and after a year, utilization of the line would be horrible. If all A380 were to produced this year, what should they do with the production line next year? A chance of another 150 orders per year coming up is unlikely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A350 production started last year while 787 started in 2011. The ramp-up of production has already happened for the 787, but not for the A350. According to Wikipedia, by 2018 the production has ramped up to 10 per month, which would outpace the 787 at the current capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Competition_between_Airbus_and_Boeing&quot;&gt;https://en.wikipedia.org/wiki/Competition_between_Airbus_and_Boeing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A350_XWB#Entry_into_service&quot;&gt;https://en.wikipedia.org/wiki/Airbus_A350_XWB#Entry_into_service&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In conclusion, I do not think they have a manufacturing problem. Keeping reasonable backlog is good for the business. &lt;/p&gt;&#xA;" OwnerUserId="9585" LastActivityDate="2015-07-30T08:38:32.503" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17406" PostTypeId="1" CreationDate="2015-07-30T11:09:38.233" Score="20" ViewCount="10093" Body="&lt;p&gt;Theoretically, could an aircraft, using any manner of self generated air flow over the (fixed) wing, ever gain enough lift in order to take off (or just simply lift off the ground) at zero forward velocity?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am guessing that if an aircraft and its engines were light enough, you might be able to provide a high enough airflow across the wings using the propellers (akin to forward motion) - although obviously I am fully aware that most of the important control surfaces would not be functional. This is just theoretical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To what end.. well... a more efficient understanding of self-generated lift (possibly?) might result from research into extreme blown flap/wing super-STOL utilization. High-lift, small transport aircraft operating out of small congested city air/heliports with very small runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am aware of the limitations of such designs, such as inefficiency at higher speeds and, in the absence of variable form and geometry (which would add too much weight) the fuel usage would become prohibitive. It's purely an idea for speculation.&lt;/p&gt;&#xA;" OwnerUserId="9590" LastEditorUserId="755" LastEditDate="2015-07-31T14:47:16.200" LastActivityDate="2018-06-19T22:13:23.937" Title="Could a blown wing ever be powerful enough to lift an aircraft at zero forward velocity?" Tags="&lt;aircraft-design&gt;" AnswerCount="7" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17407" PostTypeId="2" ParentId="17406" CreationDate="2015-07-30T12:14:15.017" Score="4" Body="&lt;p&gt;Using the &lt;a href=&quot;https://en.wikipedia.org/wiki/Coand%C4%83_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coandă effect&lt;/a&gt;, it is theoretically possible for an aircraft's engines to blow enough air over the wing to generate lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in a real aircraft the engines are placed so as &lt;em&gt;not&lt;/em&gt; to place the complete wing within their outflow. Otherwise, a large amount of drag would be constantly produced during forward flight. Engine outflow also does not have sufficient cross-section to affect the complete wing, unless a very stubby (small aspect ratio, not very efficient) wing was used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Applications have been seen in prototypes such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_YC-14&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Boeing YC-14&lt;/a&gt; or production models such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-72&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Antonov An-72&lt;/a&gt;, however these were STOL aircraft, not VTOL.&lt;/p&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="755" LastEditDate="2018-06-19T22:13:23.937" LastActivityDate="2018-06-19T22:13:23.937" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17408" PostTypeId="2" ParentId="17151" CreationDate="2015-07-30T12:51:58.040" Score="2" Body="&lt;p&gt;According to this image of the locations of the Concorde's fuel tanks:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fkJpl.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fkJpl.gif&quot; alt=&quot;Concorde fuel tank locations&quot; /&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Borrowed from: &lt;a href=&quot;http://www.concordesst.com/fuelsys.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;ConcordeSST.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;and this image of the location of the Concorde's engines:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NBkyk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NBkyk.jpg&quot; alt=&quot;Concorde engines&quot; /&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Also from &lt;a href=&quot;http://www.concordesst.com/inside/6.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;ConcordeSST.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;It doesn't appear that there is a lot of room for direct transfer of heat from the engines to the fuel tanks.&lt;/p&gt;&#xA;&lt;p&gt;Also of note, the Concorde's designers intentionally used the fuel for other cooling purposes:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The fuel is also used as a heat sink for cooling purposes. Surplus heat from the air conditioning and hydraulic systems from the constant speed drive and generator and also from the engine lubricating oil is rejected through heat exchangers to the fuel.&lt;br /&gt;&#xA;&lt;sup&gt;--&lt;a href=&quot;http://www.concordesst.com/fuelsys.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;ConcordeSST.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Based on this, I would say that the amount of fuel vaporized by engine heat was minimal at best, and, therefore, of no concern.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-04-01T09:34:18.120" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17409" PostTypeId="2" ParentId="17406" CreationDate="2015-07-30T12:56:52.433" Score="7" Body="&lt;p&gt;No, it would not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To take off vertically you need to apply vertical force equal to the weight of the aircraft and no or just a little horizontal force to possibly start moving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the total force on an aircraft (any aircraft) has opposite direction to (average) &lt;em&gt;change&lt;/em&gt; of velocity of the air flowing around the aircraft, and magnitude proportional to magnitude of the velocity change and amount of the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to lift off, the aircraft has to accelerate air &lt;em&gt;down&lt;/em&gt; a lot. In normal rolling take-off, the air is moving horizontally around the aircraft, so the wings need to only bend it down a little to generate sufficient downward acceleration and corresponding lift force. But in vertical take-off the air is not moving, so it simply needs to be accelerated downward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But a &lt;em&gt;wing&lt;/em&gt; is not capable of bending the flow by 90°, only maybe 30° or something like that, so to give the air enough vertical velocity you'd also give it even more horizontal velocity, generating a lot of thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all that thrust you would need to provide energy with the engines. It means thrust/weight ratio at least 2:1. No aircraft has that. Conventional aircraft can do with 0.2, VTOLs (including helicopters) need 1 and a bit. 2 is absurdly inefficient. And it would not be true vertical take-off as the aircraft would accelerate horizontally very fast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With circular shape Coandă effect can bend the air by more, but that does not really count as wing any more. And it still does not have any advantage over rotating the thrust vector itself. The advantage of blowing engine exhaust over the wing is not that it would be more efficient, it is that it is simpler than rotating the engines.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="7532" LastEditDate="2015-07-30T19:08:08.337" LastActivityDate="2015-07-30T19:08:08.337" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17410" PostTypeId="2" ParentId="17406" CreationDate="2015-07-30T14:09:08.183" Score="20" Body="&lt;p&gt;Technically speaking, yes, it's possible, but wildly impractical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, as usual, &lt;a href=&quot;https://aviation.stackexchange.com/a/17409/755&quot;&gt;Jan Hudec's explanation of the physics&lt;/a&gt; is completely correct. Whatever is blowing enough air over the wings to fly would generate an insane amount of forward thrust, meaning that you wouldn't stay at zero forward velocity for long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However&lt;/strong&gt;, it's completely possible to apply another force in the opposite direction equal in magnitude to what would otherwise be the net forward force produced by the engine(s) blowing the wings. This would yield a total net forward force of zero, thus no forward acceleration would happen, allowing you to take off at zero forward velocity. Of course, you'd want to make sure that whatever is applying this force isn't also blowing the wings in the opposite direction, otherwise you lose your lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Some possibilities for providing this force:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Normal jet engines mounted backwards&lt;/li&gt;&#xA;&lt;li&gt;Normal propeller engines with negative pitch&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/etzqmtYcpCQ?t=1m4s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rocket engines mounted backwards&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;A (really strong) tether&lt;/li&gt;&#xA;&lt;li&gt;Wheel brakes (this only works as long as you're on the ground, of course... you'd start accelerating forwards very quickly as the wheels break free from the ground, but you could technically leave the ground with zero forward velocity.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://what-if.xkcd.com/21/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A really big machine gun&lt;/a&gt;, such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/GAU-8_Avenger&quot; rel=&quot;nofollow noreferrer&quot;&gt;GAU-8 Avenger&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Gryazev-Shipunov_GSh-6-30&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gryazev-Shipunov GSh-6-30&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://what-if.xkcd.com/21/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lots of AK-47s&lt;/a&gt; ('lots' being a number roughly equal to the net forward thrust of the engines in pounds divided by 13)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is roughly what the backwards-mounted rockets would look like:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/4r8Sf.png&quot; alt=&quot;C-130 Rocket Assisted Landing&quot;&gt;&lt;br&gt;&#xA;C-130 Rocket Assisted Landing&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://youtu.be/etzqmtYcpCQ?t=1m4s&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility to technically meet your requirement of taking off at zero forward velocity would be to simply start off rolling &lt;em&gt;backwards&lt;/em&gt; fast enough that you would accelerate forwards to zero forward velocity at the moment the tires leave the pavement. :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, as you've hopefully figured out by now, that all of the above are wildly inefficient ways to take off. They would, however, technically work. And, of course, in the case of the GAU-8, whatever is in front of you during the takeoff is going to have a very bad day.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-09-15T03:15:57.637" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17411" PostTypeId="2" ParentId="16594" CreationDate="2015-07-30T15:26:39.137" Score="3" Body="&lt;p&gt;If the fighter has radar SA to the offending aircraft, it can very easily affect a radar interception and close to within up to .1NM of the bogey if a visual ID and escort are required.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, if a facility, such as an air intercept controller, has already deemed the aircraft to be hostile then the fighter will engage the aircraft as appropriate through the use of radar guided munitions.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In situations where an aircraft is already known to be hostile, BVR engagements will likely be the initial engagement choice anyway, and, in this case, it doesn't matter what the weather conditions are because the fighter is running an entire engagement based on his radar and will remain outside the visual arena anyway.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-07-30T15:33:50.513" LastActivityDate="2015-07-30T15:33:50.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17412" PostTypeId="2" ParentId="17396" CreationDate="2015-07-30T15:30:06.210" Score="7" Body="&lt;p&gt;You are correct that Airbus seems to be behind in the widebody market. However, it's not really a production issue, but an orders issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airliner manufacturing, the goal is not to keep backlog at a minimum, but to balance backlog with production. When a customer orders an aircraft, they will be given an estimate for when that aircraft can be delivered. Deliveries are planned years in advance. Delivering aircraft faster may actually be worse, if the customer is not yet ready to take delivery of the aircraft. It does a manufacturer no good to burn through the backlog and run out of orders. Shutting down a production line and restarting it later is more expensive than switching to a new model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 is a very large plane with not that many orders, so a slower production rate is expected. Also, &lt;a href=&quot;https://aviation.stackexchange.com/q/17374/1696&quot;&gt;as we have discussed here&lt;/a&gt;, the A380 hasn't received any new orders for a while. Airbus would prefer to keep the line going at least until they decide whether to offer a new engine or stretched version of the plane. The story is similar with the 747, except that the -8 &lt;strong&gt;is&lt;/strong&gt; the new engine/stretched version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/17402/1696&quot;&gt;Andri is correct&lt;/a&gt;; A350 just recently entered service, and a low production rate is typical for new aircraft while they work out issues. The 787 has been in production for a few years and has already established a higher production rate. Both are still fairly new and so they both have a large backlog of orders to fill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A330 does have some remaining orders, many of which are for the future neo version with new engines. The 777 has more backlogged orders, and also has an updated model in development. The 767 is an older design, and has not had any major updates for a while. Although most customers would prefer a newer model, there are still some orders left to fill, including some for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_KC-46_Pegasus&quot; rel=&quot;nofollow noreferrer&quot;&gt;tanker version&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-07-30T15:30:06.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17413" PostTypeId="2" ParentId="17406" CreationDate="2015-07-30T15:36:38.720" Score="16" Body="&lt;p&gt;What you're asking for is basically a helicopter: rather than blowing air over the wing it's more efficient to attach airfoils to a vertical axle and generate relative movement (and hence lift) by rotating them.&lt;/p&gt;&#xA;" OwnerUserId="9593" LastActivityDate="2015-07-30T15:36:38.720" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17414" PostTypeId="1" AcceptedAnswerId="17416" CreationDate="2015-07-30T15:42:06.753" Score="3" ViewCount="374" Body="&lt;p&gt;See here the &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroflot_Flight_593#Full_transcript&quot; rel=&quot;nofollow&quot;&gt;transcript&lt;/a&gt; of ending moments of Aeroflot Flight 593 . The Wikipedia writes : &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;(N.B.: All timestamps refer to the flight data recorder time, not GMT or local time.)&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What do 2265,2266...2300.....2393..2400 mean? Maybe, they don't mean seconds since CVR can record for only 30 minutes i.e. 1800 seconds..&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="65" LastEditDate="2015-07-30T17:11:39.300" LastActivityDate="2015-07-30T17:11:39.300" Title="In what manner does the Cockpit Voice Recorder timestamps?" Tags="&lt;accidents&gt;&lt;flight-data-recorder&gt;&lt;cockpit-voice-recorder&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17415" PostTypeId="2" ParentId="17365" CreationDate="2015-07-30T16:40:38.543" Score="-1" Body="&lt;p&gt;Let's take this question from a position of logic- arguably you are in the most vulnerable position with traffic approaching from behind and your recommended to sit in the dark? That does not make a lot of sense to me. The landing light would not blind the inbound traffic, but rather cast a gentle light down the runway. I see two benefits from having the light on – The controller would advise the landing traffic that there is an aircraft on the active and waiting, why not make the visibility of said aircraft a little bit easier? Also as previous mentioned the taking off traffic that is one less thing to do. Do your lights camera action when taking the active runway including the landing light&lt;/p&gt;&#xA;" OwnerUserId="9594" LastActivityDate="2015-07-30T16:40:38.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17416" PostTypeId="2" ParentId="17414" CreationDate="2015-07-30T17:11:04.103" Score="4" Body="&lt;p&gt;As described, it is the &lt;strong&gt;flight data recorder time&lt;/strong&gt;. The &lt;a href=&quot;https://youtu.be/fO11T5eKQNA&quot; rel=&quot;nofollow&quot;&gt;linked video&lt;/a&gt; in that Wikipedia article shows it as seconds. I could not find after how much time Flight 593 crashed, but 2400 seconds equal to 40 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An FDR typically records around 90 parameters, and certainly can and does monitor &lt;em&gt;all&lt;/em&gt; of them &lt;em&gt;all&lt;/em&gt; the time, even when several parameters change within a single second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the purpose of transcript for this accident, the article on Wikipedia (which is far less technical and detailed than an NTSB investigation report) omits all the entries from FDR recordings which are neither relevant to the story, nor interested to the reader. For example, the reader will care less the input from different sensors between 2303 and 2314.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since the recording time of a CVR (30 minutes - 2 hours) is less than an FDR (25 hours), they are synchronized for an investigation. This is &lt;a href=&quot;http://www.exosphere3d.com/pubwww/pdf/flight_1549/ntsb_docket/420526.pdf&quot; rel=&quot;nofollow&quot;&gt;described here (PDF)&lt;/a&gt;, for the investigation of &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow&quot;&gt;Flight 1549&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The CVR and FDR data were synchronized to one another by comparing the&#xA;  FDR “Key VHF” parameter with radio transmissions as heard on the CVR&#xA;  recording. By comparing the CVR elapsed time (time since the beginning&#xA;  of the CVR recording) for radio transmissions to the corresponding FDR&#xA;  Subframe Reference Number (SRN) for “Key VHF”, a relationship between&#xA;  the CVR elapsed time and the FDR SRN time can be developed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-07-30T17:11:04.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17417" PostTypeId="1" AcceptedAnswerId="17418" CreationDate="2015-07-30T17:39:06.653" Score="7" ViewCount="1506" Body="&lt;p&gt;Many GPS approaches have lower descent minimums labeled LPV. How do I know if my aircraft is equipped to allow me to fly to those LPV minimums? And while we're at it, it would be good to know which minimums to use from the whole array of minimums found on GPS approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/2zzYIQ4.png&quot; alt=&quot;gps lpv&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2018-02-11T06:40:08.853" Title="How do I know if I'm able to use LPV minimums on a GPS approach?" Tags="&lt;approach&gt;&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17418" PostTypeId="2" ParentId="17417" CreationDate="2015-07-30T18:03:57.597" Score="6" Body="&lt;p&gt;There are many websites / blog pages that compare and contrast the different approaches. All you need to do is google a bit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, if your plane can fly LPV approaches you'd know that. It requires WAAS-quality GPS receiver, and to install that requires at least a logbook entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that it's not only a matter of equipment. Even when the plane is equipped to fly LPV approaches, there can be certain conditions when you can't use LPV minimums (satellites, etc.) If you CAN use LPV minimums, the GPS unit MUST show you &quot;LPV&quot; in the annunciator window. It's possible that you're LPV-equipped, but your annunciator window shows you only &quot;LNAV&quot;, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, check your documents, talk to your mechanic, you wouldn't really NOT know if your plane was ever upgraded for LPV approaches. If it's your own, you'd know and have discussed it and most likely given the mechanic the task to upgrade it. If it's a rental, or you're just buying it, look at the logs and ask the seller. And keep in mind, the annunciator window will show you the lowest GPS approach type that it senses is safe. Usually on an LPV-equipped plane that will be &quot;LPV&quot;, but it's entirely possible it will only show &quot;LNAV&quot;, or something else. For you to use LPV minimums also depends on the actual &lt;em&gt;flight condition&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9483" LastEditorUserId="9483" LastEditDate="2015-07-30T18:20:19.450" LastActivityDate="2015-07-30T18:20:19.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17421" PostTypeId="1" AcceptedAnswerId="17426" CreationDate="2015-07-30T21:06:31.473" Score="8" ViewCount="845" Body="&lt;p&gt;I was reading answers to this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1446/how-long-do-airliner-tires-last-can-this-be-improved?rq=1&quot;&gt;How long do airliner tires last? Can this be improved?&lt;/a&gt; and it seems to be reasonable to keep things simple and rethread tires instead of designing motors to spin them up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However, what if one was to implement a simple aluminum housing like the one in the drawing below which will provide the following benefit.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When gear is deployed, due to friction of air only on the exposed part of tire thread, tire will spin up on it's own.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Has this ever been considered? Why would this kind of design work/not work for large airliners?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: the inside of the wheels are open for cooling purposes as well as various ducts can be incorporated for efficient cooling of the brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BKsmR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BKsmR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9146" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2017-06-01T15:05:22.483" Title="Would adding a fairing to landing gear to spin the tires before landing yield enough benefits?" Tags="&lt;landing-gear&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17422" PostTypeId="1" CreationDate="2015-07-30T21:09:10.647" Score="29" ViewCount="9531" Body="&lt;p&gt;Last weekend, while watching the second world war film &quot;Fury&quot; with a friend, there was a scene near the end with a large set of bombers flying overhead, leaving large contrails. That seemed wrong to me, as I'd thought that contrails were a jet thing, but the friend I was watching it with thought it was right. (Was a lovely shot though, accurate or not!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That has me wondering - do propeller planes generate contrails like jets do? And if so, is it only turborops that would, or is it something all propeller planes can create? &lt;/p&gt;&#xA;" OwnerUserId="9222" LastEditorUserId="3386" LastEditDate="2018-02-04T12:48:42.130" LastActivityDate="2019-04-11T22:54:56.690" Title="Do propeller planes give contrails like jets do?" Tags="&lt;jet-engine&gt;&lt;propeller&gt;&lt;contrails&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17423" PostTypeId="2" ParentId="17422" CreationDate="2015-07-30T21:14:02.207" Score="13" Body="&lt;p&gt;Yes they do. They can however have different types of contrails. Some come from propeller blade tips, while others are from engines themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Here are a few examples:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Video of A Hercules C-130:&#xA;&lt;a href=&quot;https://www.youtube.com/watch?v=n-lqoAtflP4&quot; rel=&quot;noreferrer&quot;&gt;C-130 Contrails&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/omiVT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/omiVT.jpg&quot; alt=&quot;C-130 Contrails&quot;&gt;&lt;/a&gt;&#xA;From: &lt;a href=&quot;http://contrailscience.com/&quot; rel=&quot;noreferrer&quot;&gt;Contrail Science&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YdJFi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YdJFi.jpg&quot; alt=&quot;C-130 Contrails&quot;&gt;&lt;/a&gt;&#xA;From: &lt;a href=&quot;http://airliners.net&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2015-07-30T21:14:02.207" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="17424" PostTypeId="2" ParentId="17422" CreationDate="2015-07-30T21:23:43.770" Score="41" Body="&lt;p&gt;Yes they can. That image from wikipedia showing &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-17_Flying_Fortress&quot; rel=&quot;noreferrer&quot;&gt;B-17s&lt;/a&gt; is more descriptive&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tsRdJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tsRdJ.jpg&quot; alt=&quot;B-17 contrail&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrails originate from condensation of vapor coming from internal combustion engines, regardless of being turboprop, turbojet/turbofan or cylinder engine. Vapor is a byproduct of the hydrocarbon (fuel) being combusted with the atmospheric oxygen.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-07-30T21:23:43.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17426" PostTypeId="2" ParentId="17421" CreationDate="2015-07-30T23:05:40.910" Score="7" Body="&lt;p&gt;Check out &lt;a href=&quot;https://aviation.stackexchange.com/questions/16661/how-are-forces-on-the-landing-gear-reduced-or-compensated-for-at-touchdown/16664#16664&quot;&gt;this answer&lt;/a&gt; to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/16661/how-are-forces-on-the-landing-gear-reduced-or-compensated-for-at-touchdown&quot;&gt;similar question&lt;/a&gt;. What it boils down to is that pre spinning gear has been looked into but there are implications of spinning up that kind of mass. The rotational inertia created created by doing so effects the handling of the aircraft. On a similar note its often easier to have a simple part that wears out and needs to be replaced often (like a tire) than a complex part that needs maintenance and is more likely to be problematic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The part you describe is pretty common on small aircraft to reduce drag over the wheels. As far as I know it does not aid in spinning the tires. Since the tires are more or less flush the air simply flows over them.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AvUhP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AvUhP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth these boots also can get in the way. If the plane lands hard the tires will balloon out and rub up agains the sides of the boot (depending on the tolerances) this may break the boot the tire or both. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-30T23:05:40.910" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17428" PostTypeId="1" AcceptedAnswerId="17433" CreationDate="2015-07-30T23:15:42.883" Score="6" ViewCount="492" Body="&lt;p&gt;Can any one please explain me the basic static stability of Falcon 7x on ground at aft most CG which is 38.5%MAC=12.63498m ... because as per my hand calculations i m getting around 2% load/weight on Nose landing gear... is there something wrong with my calculations or the CG doesn't really affect the aircraft stability...?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have used following method to determine the load&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Fn_{min} = \frac{Bm_{min}* W}{B}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$Fn_{min} = 4090.817398$, % of load $2.093923332$ where $Bm_{min}$ is distance from Main Landing gear to the aft most cg = $0.201 \mathrm{m}$, $W$ is the design limit weight $=19915 \mathrm{kg}$, $B$ is the wheel base $= 9.5644 \mathrm{m}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6DPxp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6DPxp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9600" LastEditorUserId="22726" LastEditDate="2019-11-16T22:34:46.547" LastActivityDate="2019-11-16T22:34:46.547" Title="Does CG location affect the stability of the Dassault Falcon 7x while on the ground?" Tags="&lt;aircraft-design&gt;&lt;stability&gt;&lt;dassault-falcon&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17432" PostTypeId="2" ParentId="17374" CreationDate="2015-07-31T05:52:44.233" Score="2" Body="&lt;p&gt;Put very simply it is an aircraft designed for a hub and spoke/star topology air network of main backbone routes connected to smaller regional routes,  launched at virtually exactly the time that carriers moved increasingly to direct point to point routes instead. &lt;br&gt;&#xA;The backbone traffic that is there is already (over) serviced by existing 747 aircraft, there is very little need for new models of either beyond flagship aircraft. Instead long range ETOPS aircraft used on point to point travel are the major seller at present. &lt;br&gt;&#xA;You could write a novel on WHY this move has happened - but it is at the core of the low sales of very large aircraft. &lt;br&gt;&#xA;Also there are currently long waits for orders of the A380, so choosing one of the two you are likely to choose the one you can get.&lt;/p&gt;&#xA;" OwnerUserId="9607" LastActivityDate="2015-07-31T05:52:44.233" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17433" PostTypeId="2" ParentId="17428" CreationDate="2015-07-31T06:18:16.187" Score="6" Body="&lt;p&gt;2% weight on nose wheel sounds plausible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all weight of an aircraft &lt;em&gt;must&lt;/em&gt; be on the main wheels. Otherwise:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the elevator would have to be huge to generate enough force to lift the nose wheel off the ground on take-off and&lt;/li&gt;&#xA;&lt;li&gt;on landing as the main gear contacts runway first it would create strong moment that would slam the nose into the ground.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/q/13132/524&quot;&gt;Why do planes always land on rear wheels instead of the nose wheels?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen values like 4% weight on the nose wheel, so 2% for CG at aft limit makes sense. It is still enough to keep the aircraft level and leave some efficiency of the steering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, loading mistake &lt;em&gt;can&lt;/em&gt; make an aircraft tip over on the tail:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/jms4K.jpg&quot; alt=&quot;MD-11 after loading mistake&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(copied from &lt;a href=&quot;https://aviation.stackexchange.com/a/16962/524&quot;&gt;this answer&lt;/a&gt;; original &lt;a href=&quot;http://www.iasa-intl.com/folders/belfast/Gemini_tipup/GeminiMD11-Dubai.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-07-31T06:23:58.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17434" PostTypeId="2" ParentId="17422" CreationDate="2015-07-31T06:18:21.953" Score="24" Body="&lt;p&gt;&quot;Contrails&quot; is a contraction of &quot;condensation trails&quot; (as opposed to &quot;chemtrails&quot; - a contraction of &quot;chemical trails&quot; [think &quot;trails&quot; left by an agricultural crop duster aircraft as it makes an application pass over a field]).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All other things excluded, condensation trails can occur when specific conditions in the atmosphere occur - certain levels of moisture (visible or not), the mass of air that contains that moisture moving from one area of pressure to a lower area of pressure, and that mass of air moving at a velocity that is commensurate with producing a change-of-state of the moisture in that mass from a non-visible state to a visible state.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When non-visible-moisture-laden air moved rapidly from a high-pressure area to a low-pressure area a rapid change of air temperature takes place due to the expansion of the space between air molecules.  In cool air water molecules clump closer together than they are in warm air, sometimes to the point that the moisture actually becomes visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All other things being equal, the faster the velocity of the moving air mass from the high-pressure area to the low-pressure area the more likely visible moisture will appear.  That is one reason you can see visible moisture coming off the propellers of the C-130's in the photos which have been submitted to this website.  The propeller tips are moving at nearly the speed of sound, their angle-of-attack relative to the air in front of them is such that they move a huge amount of air past them at a very high speed.  The amount of moisture in the air is such that when it undergoes a compression/de-compression cycle as it passes the tip of the propeller blade is is quickly compressed then de-compressed and then is appears as vapor behind the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As one contributor has already explained &quot;contrails&quot; can also come from exhaust systems of piston-driven aircraft.  Those &quot;contrails&quot; come from basically the same events - i.e., compression and then rapid de-compression of moisurized air.  The most-often seen photographs/movies which show this effect are usually of B-29 aircraft.  Most piston engines cannot operate at altitudes higher than about 20,000 feet because the air is too &quot;thin&quot; to sustain combustion in their cylinders.  B-29's, like many other late-WW 2 aircraft - were equipped with &quot;superchargers&quot; - in effect very powerful &quot;fans&quot; which pulled in atmospheric air, compressed it, then sent it into the fuel/air intakes, thus providing sufficient oxygen to sustain the fuel burn in the cylinders.  That &quot;compressed&quot; air naturally contained moisture - some of which did not completely get enough heat/pressure in the cylinders to be destroyed.  It subsequently re-formed as condensation after it left the exhaust stack - only with a vengeance because of the extreme temperature shock it experienced going from the high temperature/pressure of the combustion cylinder to the sub-zero temperatures of altitude at the high altitude these bombers were flying at. &lt;/p&gt;&#xA;" OwnerUserId="9606" LastEditorUserId="3825" LastEditDate="2015-08-01T04:03:40.153" LastActivityDate="2015-08-01T04:03:40.153" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17436" PostTypeId="2" ParentId="2252" CreationDate="2015-07-31T08:53:50.097" Score="12" Body="&lt;p&gt;Theres two different approaches, passive and active stability on all three axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X axis (roll):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the X axis, flying wings are stabilized the same as any other plane.&#xA;Passive stability is achieved through a slight upwards dihedral between left and right wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active stability is achieved through ailerons near the wing tips which create a controlled differential lift allowing the pilot or flight computer to control the roll velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Y axis (pitch)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passive stability in the Y axis in traditional planes is achieved through the high-leverage corrective force of the horizontal stabilizer (with the exception of canard type planes where the main wing itself takes this role)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active stability is achieved through elevator controls on this stabilizer, which increase or decrease the vertical force in one or the other direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a flying wing this stabilizer is not present. Instead the rearward area of the main wing takes this role. For this to work, a stable flying wing needs to have wings that are significantly swept backwards in such a way that the overall torque force at both positive and negative high angle of attack is always decreasing this angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active stability is achieved through control surfaces at the very back of the wing. These are often the same control surfaces also used for Roll control, but deflecting in unison instead of opposite directions (Elevons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Z Axis (yaw)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar to pitch, the passive and active yaw control on conventional planes is done with a stabilizer fin with a rudder at the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In true flying wings this is not present (Some don't even have winglets) But the high wing sweep (usually the wings of a  flying wings meet at roughly 90° angle at the tip) causes a higher drag force at the forward facing wing if the craft yaws to one side, which enacts the required corrective force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active control is achieved by causing additional drag through some sort of braking flaps near the wing tips (the actual implementations vary - split elevons - separate break flaps - ...) This can also be augmented by using differential thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note: The corrective force is much lower than that caused by a tail fin. As such a powered flying wing should have its engines relatively close to the center, otherwise a one-engine-out scenario would cause an uncorrectable yawing moment. This however limits the effectiveness of differential thrust if the craft is supposed to stay flyable in such a condition)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed and stall stability:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A speed stable plane has its nose pitch up at higher speeds and pitch down if the craft gets slower, thanks to the center of gravity being in front of the center of lift, which causes the nose to drop. This is balanced out by a (usually parasitic) downward force from the horizontal stabilizer acting at the tail of the plane. This arrangement of forces should also cause the nose to drop and the angle of attack to reduce in a stall situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a flying wing does not have this stabilizer, a similar balance of forces needs to be achieved through a careful design of wing profile and twist.&#xA;If you look at Horton flying wing glider designs for example, they have a &quot;thick&quot; profile creating the majority of lift in the center (which thanks to the wing sweep is also the front)  Towards the end and back of the wings, the profile becomes thinner and more symmetric. At the same time, the wings are slightly twisted, so the intrinsic angle of attack is a few degree lower at the tip (and as such at the rear of the wing) than near the nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high speeds, the front of the wing creates more lift than the back and rises the nose. This part has the highest wing load and will stall first, while the swept back outer wing area - thanks to its profile, lower AoA and lower load will not have stalled yet. The nose drops, and the control surfaces in this rearward part stay functional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that not all flying wing designs did achieve a safe stall behavior. Some, like early 1940's and 1950's American designs failed to implement stall stability correctly, while others (like the B2 bomber) the plane was deliberately designed aerodynamically unsafe to faciliate other features (stealth) which would have been compromised by a &quot;twisted&quot; wing.&lt;/p&gt;&#xA;" OwnerUserId="9611" LastEditorUserId="8114" LastEditDate="2019-09-11T12:35:51.900" LastActivityDate="2019-09-11T12:35:51.900" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="17437" PostTypeId="1" AcceptedAnswerId="17464" CreationDate="2015-07-31T09:06:57.680" Score="11" ViewCount="3300" Body="&lt;p&gt;Do you have any info on this strange wing endings used on Stemme glider?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5W2UA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5W2UA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Untitled/Stemme-S-10V/1041849&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Source&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="14897" LastEditDate="2016-09-15T00:01:07.510" LastActivityDate="2016-09-15T00:01:07.510" Title="Any info on very strange wing endings on this Stemme glider?" Tags="&lt;aerodynamics&gt;&lt;glider&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17438" PostTypeId="2" ParentId="17406" CreationDate="2015-07-31T11:20:17.750" Score="0" Body="&lt;p&gt;JulianHzg asked if a surface with a large (70-80 degree) deflection angle could be called a wing.  The Harrier has such a surface.  If we are willing to call the exhaust nozzles &quot;wings&quot; then we have a working example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2RlL0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2RlL0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9004" LastActivityDate="2015-07-31T11:20:17.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17439" PostTypeId="1" CreationDate="2015-07-31T11:52:03.023" Score="16" ViewCount="479" Body="&lt;p&gt;On or about July 30, 2015, the initial news could have been worded like: &quot;debris appears to have come from a Boeing 777&quot;. As the story evolved, additional details emerged such as the wreckage being part of a 777 flaperon, before being decisively announced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: what was the forensic/investigative process which would have produced the initial speculative-sounding announcement associating the debris to a 777, before ultimately becoming the more definitive statement?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put it another way: what steps had investigators taken up to the point of each announcement, and how was the debris recognized very early on as part of a 777 without actually being confirmed as such? Is it investigator experience? If initial identification was made by part numbers, why would there have been any doubt in the announcement?&lt;/p&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="62" LastEditDate="2015-07-31T12:59:43.960" LastActivityDate="2015-10-15T22:35:41.453" Title="What was the forensic process underlying the recent news regarding MH370 debris?" Tags="&lt;mh370-incident&gt;&lt;boeing-777&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17440" PostTypeId="1" AcceptedAnswerId="19319" CreationDate="2015-07-31T12:47:49.653" Score="11" ViewCount="2133" Body="&lt;p&gt;I understand the basic concept of the pitot &lt;em&gt;tube&lt;/em&gt; in that it measures the air pressure coming into the tube in order to compare it to a static pressure measured elsewhere on the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot;&gt;B-2 bomber&lt;/a&gt;, however, has &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#Flight_controls&quot;&gt;pitot &lt;em&gt;plates&lt;/em&gt;&lt;/a&gt; in order to eliminate the radar reflectivity of the pitot tube. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do these plates work, as compared to tubes, and why aren't they more common, since a flat surface that is less radar reflective would also, likely, be more aerodynamic?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2019-01-31T12:13:46.963" Title="How does a pitot plate work?" Tags="&lt;aircraft-design&gt;&lt;flight-instruments&gt;&lt;pitot-static&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17441" PostTypeId="1" AcceptedAnswerId="17462" CreationDate="2015-07-31T13:16:48.230" Score="9" ViewCount="1343" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cebu_Pacific&quot; rel=&quot;noreferrer&quot;&gt;Cebu Pacific&lt;/a&gt; is a Philippine low-cost airline , which has 6 A330 in its fleet. The capacity of each of them is &lt;strong&gt;436&lt;/strong&gt; . As far as I know, one of the reasons why airlines introduce First Class cabins is because its impossible for them to fly with a huge number of passengers and their luggage. It makes the plane very heavy and less fuel efficient. That's why, we don't have any A380 with more than a capacity of 550 , against its maximum of 853. But, how does Cebu Pacific makes profits from operating a 436 seater A330( which commonly has a capacity of 300 people)? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-05T12:07:42.783" LastActivityDate="2016-04-28T15:56:46.240" Title="How is a 436 seater A330 fuel efficient?" Tags="&lt;cost&gt;&lt;efficiency&gt;&lt;airbus-a330&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17442" PostTypeId="2" ParentId="17441" CreationDate="2015-07-31T13:41:04.397" Score="4" Body="&lt;p&gt;I don't know if the A330 runs into weight and balance problems with 436 passengers AND full fuel.  It is very common, however, in small planes for the plane to be over max gross weight with all the seats full and also with tanks full.  You have to restrict how many passengers you carry, or make intermediate stops for more fuel.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since Cebu Pacific has many shorter leg lengths perhaps they can fill all the seats and still take on board needed fuel plus reserves and be below gross weight restrictions.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you point out, adding business and first class seating reduces the overall weight of the passenger load.  On a weight restricted flight, that alone will increase overall revenue.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-07-31T13:41:04.397" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17443" PostTypeId="2" ParentId="1389" CreationDate="2015-07-31T13:41:39.947" Score="6" Body="&lt;p&gt;As mentioned they are efficient at lower altitudes (and service the GA mission quite nicely) but in many ways it simply boils down to cost. There are companies out there designing and working on smaller jets like &lt;a href=&quot;http://cirrusaircraft.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cirrus&lt;/a&gt; with the &lt;a href=&quot;http://cirrusaircraft.com/aircraft/vision-sf50/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SF50&lt;/a&gt;. Then there are a few jets out there like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_Citation_Mustang&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna Citation Mustang&lt;/a&gt; that are single pilot certified and can be flown with appropriate ratings on a PPL. But the fact remains that it is &lt;strong&gt;not cheap&lt;/strong&gt; nor easy to bring a new airplane to market. Cirrus first flew their jet in 2008 and its still not on the market officially. That puts them at nearly 8 years from prototype to roll out and Im sure the first lines for it were drawn well before 2008. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand companies like &lt;a href=&quot;http://www.piper.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper&lt;/a&gt; and &lt;a href=&quot;http://cessna.txtav.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna&lt;/a&gt; have approved designs that are still fast and easy to maintain even by todays standards. Very much the &quot;If it ain't broke don't fix it&quot; issue. It is no mystery that GA sales are down and some of the companies could be doing better. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a bit of a safety issue. Propeller planes are nice and easy to fly with fast throttle response and lower speeds they make great trainers. Some may argue that jets are just to much plane to handle for a new pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth there are some very fast piston singles out there. The &lt;a href=&quot;http://www.glasairaviation.com/glasair.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Glasair&lt;/a&gt; claims a cruise of 252Ktas (although its experimental) and the full production &lt;a href=&quot;http://www.mooney.com/aircraft/acclaim-type-s/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mooney Acclaim Type S&lt;/a&gt; pulls in at 242Ktas both of these planes approach turbo prop speeds to the piston engine while an old design can still deliver performance (and high speeds). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also some cross over with automotive piston engines. Through out history there have been a few auto engines certified for aircraft. Once upon a time &lt;a href=&quot;http://generalaviationnews.com/2015/07/13/in-search-of-the-700-airplane/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ford had some motors&lt;/a&gt; that found their way into planes. Mooney has attempted to use car motors at least twice starting with the &lt;a href=&quot;http://www.mooneymite.com/articles-history/jackcoxreport.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Crosley engine&lt;/a&gt; that was found in early Mites and culminating with the epic (if you are a Porsche fan like me) &lt;a href=&quot;https://en.wikipedia.org/wiki/Porsche_PFM_3200&quot; rel=&quot;nofollow noreferrer&quot;&gt;PFM3200 that featured the Porsche 3.2&lt;/a&gt; engine out of the late 80's Carrera. While the PFM3200 was riddled with issues and Porsche eventually dropped the FAA certification for the motor it was an interesting display of engineering. Parts for the 3.2 were arguably easier to come buy and there were plenty of people who knew how to work on them. Currently Diamond offers a &lt;a href=&quot;http://www.diamond-air.at/twin-engine-aircraft/da42-ng.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;diesel DA42&lt;/a&gt; that runs on modified car motors. Again using a motor that is tried and true on the road. So the costs are not just because the engines are cheaper to make but made in much higher quantities as well as being able to offset some of the engineering costs with this bulk.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2017-10-22T18:52:43.917" LastActivityDate="2017-10-22T18:52:43.917" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17445" PostTypeId="1" CreationDate="2015-07-31T14:24:01.360" Score="2" ViewCount="303" Body="&lt;p&gt;For an example, I am talking about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_812&quot; rel=&quot;nofollow&quot;&gt;Southwest Airlines Flight 812&lt;/a&gt; where there was a small tear in the fuselage section caused as a result of metal fatigue. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why didn't the tear affect other sections of the fuselage? &lt;/li&gt;&#xA;&lt;li&gt;Is there any specific design feature involved to prevent such a situation or is it just plain luck that it did not happen?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7653" LastEditorUserId="5517" LastEditDate="2015-07-31T18:52:38.603" LastActivityDate="2015-07-31T18:52:38.603" Title="What design feature prevents the fuselage skin from completely tearing off?" Tags="&lt;commercial-aviation&gt;&lt;airliner&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17446" PostTypeId="2" ParentId="17445" CreationDate="2015-07-31T14:55:03.013" Score="4" Body="&lt;p&gt;In the 1980's, manufacturers thought that they had solved the problems that plagued earlier models like the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow&quot;&gt;De Havilland Comet&lt;/a&gt;. Then &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot; rel=&quot;nofollow&quot;&gt;Aloha Airlines Flight 243&lt;/a&gt; had a large section of upper fuselage come off during flight. Manufacturers realized that the fuselage could accumulate more damage more quickly than expected, and when this damage went undetected, it resulted in catastrophic failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The result was both regulators and manufacturers emphasizing a focus on both &lt;a href=&quot;http://lessonslearned.faa.gov/DanAir/FS_vs_DTl.pdf&quot; rel=&quot;nofollow&quot;&gt;damage tolerance and fail safety&lt;/a&gt; when designing these structures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Damage tolerance&lt;/strong&gt; means that the structure can tolerate a certain amount of damage while still performing its function. Inspections should be performed soon enough that they will detect the damage before it compromises the structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fail safety&lt;/strong&gt; means that even if a feature fails, the overall structure can still perform its function. One option for this is redundancy. In the fuselage, this means stopping cracks from propagating too far. The cracks in the Aloha Airlines incident were able to continue growing until a large portion of structure failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These ideas mean that the structure is designed so that any damage is caught before it becomes critical, but in the event that this is not sufficient, items can fail without endangering the safety of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example is what happened to &lt;a href=&quot;https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_812&quot; rel=&quot;nofollow&quot;&gt;Southwest Flight 812&lt;/a&gt;. A section of fuselage ripped open in flight, which resulted in a rapid depressurization but a safe landing. A crack formed in the fuselage and was not detected. However, the crack was contained in a limited section of the skin. This allowed the cracked skin to fail while the rest remained intact.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-07-31T14:55:03.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17447" PostTypeId="1" AcceptedAnswerId="17449" CreationDate="2015-07-31T15:06:43.010" Score="3" ViewCount="235" Body="&lt;p&gt;Instead of providing the maximum capacity of a particular model, airliner manufacturers often provide official &lt;em&gt;typical&lt;/em&gt; capacities, like &lt;a href=&quot;http://www.a350xwb.com/technical-specifications/&quot; rel=&quot;nofollow&quot;&gt;280-366 seats&lt;/a&gt; for A350 series and &lt;a href=&quot;http://www.boeing.com/commercial/777x/#/technical-specs&quot; rel=&quot;nofollow&quot;&gt;350/400seats&lt;/a&gt; for Boeing 777x series.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is: How do they generate this number?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="923" LastEditDate="2015-07-31T15:43:58.320" LastActivityDate="2015-08-03T21:42:37.713" Title="How do airliner manufacturers come up with typical capacities of their planes?" Tags="&lt;aircraft-design&gt;&lt;airbus&gt;&lt;boeing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17448" PostTypeId="2" ParentId="17447" CreationDate="2015-07-31T15:20:21.487" Score="3" Body="&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-27E.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA average passenger weight (adult male)&lt;/a&gt; is 200 LBS in the summer and 205LBS in the winter, you can extrapolate seats from that number. It is assumed that there is one passenger to a seat. You would also need to assume that the worst case is a plane full of adult winter males (205LBS) plus luggage. The document linked goes over how to calculate average baggage weights and what some rough percentages are on that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that people who are above standard size may be required to buy 2 seats. This is generally handled on a case by &lt;a href=&quot;https://www.delta.com/content/www/en_US/traveling-with-us/special-travel-needs/require-extra-seat-space.html&quot; rel=&quot;nofollow&quot;&gt;case basis it seams&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-07-31T15:32:12.640" LastActivityDate="2015-07-31T15:32:12.640" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17449" PostTypeId="2" ParentId="17447" CreationDate="2015-07-31T15:34:44.073" Score="4" Body="&lt;p&gt;These numbers are based on mixed-class configurations and use of floor space for other things. The A380 for instance can theoretically be configured with 853 &quot;economy&quot; seats, but no-one I know of has bought one configured that way. Typical first-business-economy configuration is 525, and Emirates seats just 489 because its first-class section is basically staterooms, and it has showers and a bar taking up floor space (it also has an excellent and large business class instead of using the back half of both decks for coach).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When designing an aircraft's seating capacity, especially for long-haul flights, total cabin weight (passengers and cargo) must be taken into account. The more stuff you're hauling, the less weight allowance you have for fuel, and therefore your range is reduced. Therefore, increased room per passenger on long-haul flights isn't just for passenger comfort, it's often a necessity to reduce total cabin weight and thus be able to max out the fuel load to get between the airports non-stop. Operators of shorter flights don't care as much because you can pack them in like sardines and still have plenty of fuel to get them where they're going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, dimensions of various classes of seat differ by airline, aircraft and route (Lufthansa, for instance, operates three different A380 configurations based on the routes they run). The typical coach seat is between 17 and 19 inches wide (including half the armrest), and has a &quot;pitch&quot; (space between seats which determines the legroom and ability to recline) of between 31 and 35 inches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For business class in three-class planes it gets a bit better; seat width averages about 21&quot; and a pitch of about 38&quot; (more for planes outfitted with lay-flat seats). First class ranges widely by aircraft type and airline (it's truly &quot;first-class&quot; in aircraft with three-class configuration; in two-class what's called &quot;first&quot; is closer to business class), but typically offers room to spare especially on long-hauls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coupled with required/desired aisle widths and additional amenities that widen the seats or replace them in certain areas of the cabin, it's fairly academic to count up how many seats you can fit aboard a particular airframe.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-03T21:42:37.713" LastActivityDate="2015-08-03T21:42:37.713" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17450" PostTypeId="2" ParentId="1389" CreationDate="2015-07-31T16:03:59.820" Score="4" Body="&lt;p&gt;Piston-driven propeller powerplants are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Cheaper.&lt;/strong&gt; Because the engine is a proven and well-understood design, they're cheaper to design, to make, and to maintain, all of which lower expenses for the pilot. You can pick up an older Piper Cherokee for about \$40k nicely equipped with plenty of hours before its next overhaul. The absolute cheapest Piper turboprop I can find with a quick search is a twin-engine Cheyenne for \$275,000, and it probably needs work as they average closer to \$400k. Other turboprop airframes approach $2 million a pop.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Smaller.&lt;/strong&gt; A four-cylinder air-cooled naturally-aspirated piston engine is not much bigger than the V-twin on a motorcycle. Smaller tends to equal lighter, and it also allows for more cabin room in a fuselage of the same total volume, and less variance of the CG with cabin weight (which is a big deal in small planes).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Simpler.&lt;/strong&gt; There's not as much to go wrong with a fixed-pitch air-cooled piston-engine plane. This again reduces maintenance costs but also increases safety by lengthening &quot;mean time between failures&quot; that would require emergency procedures. Constant-speed props are a little more mechanically complex but not too bad. Turboprops a little more complex still.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Better-performing at low altitudes.&lt;/strong&gt; Most turbofans are designed for operation above 10,000 feet, while most propeller-driven craft are designed to fly at 8,000 or below because their cabin is unpressurized. At lower altitudes where the air is thicker, piston engines run more efficiently and cooler than turbofans and much better than pure jets.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-07-31T16:03:59.820" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17451" PostTypeId="2" ParentId="17198" CreationDate="2015-07-31T16:47:14.513" Score="9" Body="&lt;p&gt;To answer the more general case of what happens if a military plane has an unrecoverable emergency near the airspace of an unfriendly nation. The crews has a number of choices:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Declare an emergency and land in the unfriendly nation. The unfriendly nation is obliged (morally and under international law) to allow them to land. However the plane and its crew then become &lt;em&gt;interned&lt;/em&gt;, which is a bit like being a prisoner of war, without the war. What happens then is up to the interning nation, and depends on the state of relations with the aircraft owner. The plane may be returned after some diplomatic maneuvering, possibly following a detailed technical examination. Or it may not. The crew may be returned, again possibly after some sort of questioning. Or they may not. During the Cold War, US pilots downed in Russia were sometimes held prisoner for years, and interrogated extensively (to put it mildly).&lt;/li&gt;&#xA;&lt;li&gt;Do their best to make it home or to a friendly base, even if such a hope seems doomed. This is likely the orders of a plane with highly sensitive technology, or anything else the nation really doesn't want other nations to get their hands on. &lt;/li&gt;&#xA;&lt;li&gt;Abandon the plane in such a way as to give the crew a reasonable chance of survival, but assuring the destruction of the plane, such as pointing it out to sea and ejecting.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="289" LastActivityDate="2015-07-31T16:47:14.513" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17454" PostTypeId="1" AcceptedAnswerId="17456" CreationDate="2015-07-31T18:23:26.923" Score="13" ViewCount="910" Body="&lt;p&gt;When reading &lt;a href=&quot;http://www.cnn.com/2015/07/31/world/mh370-debris-investigation/&quot;&gt;this article on the debris they found from Flight MH370&lt;/a&gt; they mention a lab in France that is supposed to be able to look at the debris (a flaperon), and figure out if the flight had exploded in mid-air or if it had broken up on impact with the ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has left me wondering, how would they do that?  How can the folks from that lab tell from an exterior control surface&lt;sup&gt;1&lt;/sup&gt; that the plane had exploded or broken up on impact?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;em&gt;Examples may include &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevon&quot;&gt;elevons&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flaperon&quot;&gt;flaperons&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevator_(aeronautics)&quot;&gt;elevators&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/V-tail&quot;&gt;ruddervators&lt;/a&gt;, basically anything that helps the plane maneuver and is exterior to the fuselage.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-07-31T19:50:58.950" LastActivityDate="2015-07-31T20:18:01.590" Title="How can investigators tell the difference between impact damage and explosion damage when investigating debris from a crash?" Tags="&lt;accident-investigation&gt;&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17455" PostTypeId="2" ParentId="17439" CreationDate="2015-07-31T18:38:51.540" Score="7" Body="&lt;p&gt;If you bring an NTSB investigator a piece of 2024 sheet aluminum with zinc chromate primer and a urethane topcoat all they can tell you is &quot;It's 2024 sheet aluminum, with some paint on it.&quot; - BUT if you bring them a piece of 2024 aluminum riveted to a  structure that looks like this:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/q4ojP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/q4ojP.jpg&quot; alt=&quot;Debris photo&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;and tell them &quot;I found it on an island in the Indian Ocean&quot; they can infer  lot more.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In this particular case they've found some debris, and they know a few things:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The debris was found in an area where it's reasonable it could be part of MH370.&lt;/strong&gt;&lt;br&gt;&#xA;The location isn't conclusive in and of itself, but it's certainly a factor that strongly implies this could be part of the missing aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The part LOOKS like it came off an airplane.&lt;/strong&gt;&lt;br&gt;&#xA;It's aircraft aluminum, riveted to a skeleton that gives it an airfoil shape. That warrants further investigation by itself (even if we didn't lose an airplane in that area recently it's clear that some part fell off some airplane at some point in time, and investigators generally want to know &lt;em&gt;which&lt;/em&gt; airplane had bits falling off).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;That leaves us with the question &lt;strong&gt;Could this part have come from the airplane we lost?&lt;/strong&gt;  &lt;a href=&quot;http://www.bbc.com/news/world-asia-33714780&quot; rel=&quot;nofollow noreferrer&quot;&gt;which is the stage we're at now&lt;/a&gt;, and there are many ways to make this determination.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You might get lucky and recover &lt;a href=&quot;https://i.stack.imgur.com/LXv3l.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;the aircraft ID plate&lt;/a&gt;, or a chunk of the tail with the N number.&lt;br&gt;&#xA;There's confirmatory testing to be sure it's not a well-perpetrated hoax, but these are pretty definitive identification elements. Unfortunately that's not the case here, so we move on.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you recover what appears to be a control surface you'll usually find a manufacturer stamp somewhere on the part, or a serial number plate. They'll certainly be inspecting this debris to look for that kind of data tag. (The data tag below is from a Piper control surface but Boeing probably uses similar plates).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ncwSd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ncwSdm.jpg&quot; alt=&quot;Control surface part data tag&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you don't find a data tag maybe there's airline livery on the debris.&lt;br&gt;&#xA;This at least lets you know whose plane you've found, but that's not applicable here as the debris in question appears to be painted basic white.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Failing all of that you compare what you've found to manufacturer's drawings of the aircraft you think it came from and see if the dimensions match any parts or sections of that aircraft.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are other possible steps and confirmatory testing involved (metallurgy, mass spectrometry on the paint, etc.) to determine if it's likely this part came from the aircraft you think it did, but that's getting into the territory where you'd be better off &lt;a href=&quot;http://www.ntsb.gov/training_center/Pages/TrainingCenter.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;signing up for training courses in accident investigation&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-31T18:38:51.540" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17456" PostTypeId="2" ParentId="17454" CreationDate="2015-07-31T18:57:54.533" Score="10" Body="&lt;p&gt;The short answer (to the question in your subject line) is that in an explosion the skin is blown outward, and in impact damage it's (usually) blown inward: In other words you can tell the direction of the force applied by which way the skin around a break/penetration is bent, if you recover the right bits of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The labs start with &quot;Boom = Outie, Crash = Innie&quot;, and they can also look at burn patterns (on the paint or as changes in the heat treatment of the metal), chemical residue (if it hasn't all washed away or been contaminated), etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to leaving chemical traces or heat-related damage explosions also tend to be physically &quot;messy&quot;, so there's usually some physical evidence. Shrapnel punctures through control surfaces are a distinct possibility in an explosion (those punctures generally have a different characteristic than denting and tearing from impact with rocky ground, and again if you get lucky you might even find bits of shrapnel inside the punctured control surface). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer answer (to the rest of the question) is that sometimes you can't conclusively tell what happened, particularly from just a single piece of wreckage like a control surface.&lt;br&gt;&#xA;In fact quoting from the story you linked there are three different (and valid) theories about what could have caused the damage seen on the particular piece of debris in question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The rear damage could have been caused if the airliner had its flaperon down as it went into the ocean, some members of Exner's group wrote in a preliminary assessment after looking at photos and videos of the component.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Entirely plausible: Impacting water at speed could tear chunks out of the trailing edge of a flaperon. It could also break the control surface free of the rest of the wing.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But the lack of damage to the front makes it more likely the plane was in a high-speed, steep, spiral descent and the part fluttered until it broke off, the group said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also plausible: Aerodynamic flutter could break pieces of the flaperon off, or tear the entire control surface from the aircraft (in which case damage may be evident at the points where the flaperon attached to the rest of the wing)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The lack of damage to the front section &quot;tells me that the component could still have likely been back in its original position inside the wing itself,&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Still plausible but a bit more exotic: The flaperon could have broken off post-impact (and the damage to the trailing edge could have occurred on impact, post-impact, or even pre-impact while the aircraft was still flying).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that a lot of what's being put forth in that article (and others) is speculation based on a few photos showing only part of the debris (so far I haven't seen any showing the &quot;bottom&quot; of the debris). A conclusive determination can only be made when the debris is recovered and examined in its entirety.&lt;br&gt;&#xA;Attempting to draw conclusions without the full picture can lead to interesting results: The apple is perfect until you see the other side.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Ar3eR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ar3eR.jpg&quot; alt=&quot;half-rotten apple&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="511" LastEditDate="2015-07-31T20:18:01.590" LastActivityDate="2015-07-31T20:18:01.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17457" PostTypeId="1" AcceptedAnswerId="17458" CreationDate="2015-07-31T19:36:19.423" Score="12" ViewCount="1467" Body="&lt;p&gt;In &lt;em&gt;Air Force One&lt;/em&gt; a fighter jet maneuvers between a missile and the president's plane, as shown &lt;a href=&quot;https://youtu.be/TtDIyYwfQkI?t=4m3s&quot; rel=&quot;noreferrer&quot;&gt;in this clip&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is such a maneuver possible?&lt;br&gt;&#xA;If not, what &lt;em&gt;could&lt;/em&gt; be done in that situation?&lt;/p&gt;&#xA;" OwnerUserId="9494" LastEditorUserId="64" LastEditDate="2015-08-04T16:38:18.320" LastActivityDate="2015-08-04T16:38:18.320" Title="Is it possible to &quot;take a bullet [missile]&quot; for another plane as shown in the movie Air Force One?" Tags="&lt;maneuver&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17458" PostTypeId="2" ParentId="17457" CreationDate="2015-07-31T20:10:49.077" Score="20" Body="&lt;p&gt;Possible and Plausible are two different things.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Is it &lt;em&gt;possible&lt;/em&gt; to fly a fighter jet between a missile and another aircraft, and either (a) confuse that missile so it follows the fighter instead) or (b) have the fighter be hit by the missile instead of the original target aircraft? Yes.&lt;br&gt;&#xA;Modern fighters are capable of maneuvering in the manner shown: they can even sustain knife-edge flight or vertical climb for a while. It's even possible that in a moment of desperation a pilot would attempt such a maneuver, sacrificing themselves and their aircraft to save their commander-in-chief.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The G-forces involved in these maneuvers may be unpleasant or even unbearable for the pilot, but if you're committing yourself to a course of action that ends with your plane blowing up to save another plane the G-forces are probably the least of your concerns.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It isn't &lt;em&gt;plausible&lt;/em&gt; that such a maneuver would work - at least not as depicted in the movie.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Missiles are REALLY FAST - &lt;a href=&quot;https://www.youtube.com/watch?v=OLnMcPL8PLo&quot;&gt;this footage includes several slow motion shots of an air-to-air missile as it's fired&lt;/a&gt; (at it's slowest relative velocity), and it's still pretty darn quick: It's gone in a few frames of high-speed footage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this maneuver to work the intercepting pilot would need to be in exactly the right position and exactly the right time, and perform the maneuver perfectly in order to intercept the missile: A little error in any direction - too fast, too slow, too far left, or too far right - and the  missile would fly right past them and continue on toward its target.&lt;br&gt;&#xA;The intercept is further complicated by the fact that, assuming the missile is guided, both the missile and the target are maneuvering as well.&lt;br&gt;&#xA;(If it's a non-guided &quot;dumb&quot; missile all the target aircraft needs to do is change course to avoid being hit - a maneuver that might stress the airframe a bit, but certainly less than &lt;em&gt;being hit by a missile&lt;/em&gt; would.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To give a little more context, the &quot;anti-missile missile&quot; programs have often been described as having your friend throw a baseball over the roof of your house while you stand on the other side and try to hit it with a golfball as it comes over the top.&lt;br&gt;&#xA;This intercept is of similar difficulty, except the balls involved are all steering themselves toward different objectives.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-07-31T20:10:49.077" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17461" PostTypeId="2" ParentId="17083" CreationDate="2015-07-31T21:23:08.530" Score="4" Body="&lt;p&gt;&lt;strong&gt;Follow the black holes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea about this one. I looked at the airport diagrams and arrival/departure procedures for &lt;a href=&quot;https://skyvector.com/airport/MIA/Miami-International-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;MIA&lt;/a&gt;, &lt;a href=&quot;https://skyvector.com/airport/MCO/Orlando-International-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;MCO&lt;/a&gt; and &lt;a href=&quot;https://skyvector.com/airport/ORL/Executive-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;ORL&lt;/a&gt; and I couldn't see anything that seems like it could be confused with the words &quot;black hole&quot;. So, I have two guesses:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's the code name for a set of &lt;a href=&quot;https://aviation.stackexchange.com/q/14018/62&quot;&gt;local taxi instructions&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;As you suggested, it's the controller's slang for &quot;the twin-engine aircraft in front of you&quot;, i.e. the black holes are the exhausts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I think the second possibility is very unlikely, though. A controller at a major international airport - which implies many pilots with English as a second language - is unlikely to use non-standard phrasing for a critical instruction like which aircraft to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Taxi not too deep&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is a lot clearer from the updated &lt;a href=&quot;https://aviation.stackexchange.com/questions/17083/slangs-on-phraseology#comment40241_17083&quot;&gt;comment&lt;/a&gt; you gave: &quot;CLEARED PUSHBACK, NOT TOO DEEP, THERE IS A TRAFFIC PASSING BEHIND YOU&quot;. That's exactly what it sounds like: the aircraft was cleared to &lt;a href=&quot;https://en.wikipedia.org/wiki/Pushback&quot; rel=&quot;nofollow noreferrer&quot;&gt;push back&lt;/a&gt; from the gate, but the ground controller was warning the pilot not to push back too far (&quot;too deep&quot;) because of another aircraft passing behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How is your ride?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is ATC asking a pilot for a &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilot_report&quot; rel=&quot;nofollow noreferrer&quot;&gt;PIREP&lt;/a&gt;. That could be because another aircraft nearby is in turbulence and trying to find a smoother altitude, so the controller asks other aircraft about the ride at their flight levels. Or, since you heard this in the US, it could be for this reason, from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM section 7-1-20&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FAA air traffic facilities are required to solicit PIREPs when the&#xA;  following conditions are reported or forecast: ceilings at or below&#xA;  5,000 feet; visibility at or below 5 miles (surface or aloft);&#xA;  thunderstorms and related phenomena; icing of light degree or greater;&#xA;  turbulence of moderate degree or greater; wind shear and reported or&#xA;  forecast volcanic ash clouds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are there other examples of slang?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are, although slang in general is discouraged because of the potential for misunderstandings. The FAA has a &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;pilot/controller glossary&lt;/a&gt; to make sure that everyone is using the same words and phrases as far as possible (ICAO provides one too), but that doesn't mean that people always stick to it 100% of the time. Ex-military pilots - and controllers - in particular sometimes use some military terminology (e.g. &lt;a href=&quot;http://guidance.aero/bingo-fuel-never-say/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;bingo fuel&lt;/em&gt;&lt;/a&gt;) out of habit (presumably) even though they really shouldn't in a civilian setting.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-07-31T21:23:08.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17462" PostTypeId="2" ParentId="17441" CreationDate="2015-07-31T21:57:53.890" Score="24" Body="&lt;p&gt;First of all, keep in mind that the Philippines has one of the shortest average populations on Earth. Their average passenger weighs &lt;em&gt;a lot&lt;/em&gt; less than an average American or European, since weight scales roughly with &lt;em&gt;the cube&lt;/em&gt; of height. So, 436 Filipinos don't weigh nearly as much as 436, say, Americans or Europeans, assuming average populations from each group. &lt;a href=&quot;https://en.wikipedia.org/wiki/Human_height#Average_height_around_the_world&quot; rel=&quot;noreferrer&quot;&gt;According to Wikipedia&lt;/a&gt;, the average Filipino male of age &gt;= 20 is only 5' 3.5&quot; (162cm) and the average female age &gt;= 20 is 4' 11&quot; (150 cm.) Compare those numbers to 5' 9.5&quot; (176 cm) for males and 5' 4&quot; (162 cm) for females for Americans age &gt;= 20. Considering the roughly cubic scale, that's a pretty significant mass difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, why would putting more passengers on board &lt;em&gt;not&lt;/em&gt; be fuel efficient? It will make the aircraft heavier, but it also means that you're carrying that many more people in one trip. My guess would be that you'll burn &lt;em&gt;less&lt;/em&gt; fuel per passenger-mile, rather than more. To get a rough estimate, &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330#Specifications&quot; rel=&quot;noreferrer&quot;&gt;an A330-300 has an operating empty weight of about 274,500 lb. and it can carry about 175,170 lb. of Jet-A&lt;/a&gt;. If we assume the average Filipino weighs about 120 lb. (this seems like a reasonable guess based on my experiences in the Philippines,) 436 passengers would come out to 52,320 lb. while the 293 passengers on &lt;a href=&quot;http://www.seatguru.com/airlines/Delta_Airlines/Delta_Airlines_Airbus_A330_200_new.php&quot; rel=&quot;noreferrer&quot;&gt;Delta's A330-300 seat configuration&lt;/a&gt; would be 35,160 lb. So, you're increasing mass before fuel by only around 5.5% while increasing passenger count by &lt;strong&gt;a whooping 49%&lt;/strong&gt;. It would be hard to find a scenario in which that does &lt;em&gt;not&lt;/em&gt; use less fuel per passenger-mile (unless, of course, you're overweight and can't take off at all.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Regarding the issue of avoiding being overweight (and, thus, being able to take off,) Cebu Pacific normally doesn't run routes anywhere near the 6,100 nmi range of a fully-loaded A330-300. This means that they won't need to carry a full fuel load. Even a 10% reduction in fuel load from the maximum capacity of an A330-300 would equal the entire added weight of going from 293 passengers to 436. Even at full fuel load, though, judging from the previously-referenced numbers on Wikipedia, we get:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operating Empty Weight (OEW): 274,500 lb.&lt;br&gt;&#xA;Full Fuel Load: 175,170 lb.&lt;br&gt;&#xA;436 120 lb. passengers: 52,320 lb.&lt;br&gt;&#xA;14 flight + cabin crew x 120 lb. = 1,680 lb.&lt;br&gt;&#xA;Total before cargo: 503,670 lb.&lt;br&gt;&#xA;Maximum Takeoff Weight (MTOW): 534,000 lb.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, that still leaves 30,000 lb. for cargo and anything else that's needed, even if they did need to carry a full fuel load for some reason.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The issue of why Cebu Pacific doesn't offer Business/First class cabins was also mentioned. The reasons for this are mostly their target demographic and their route network (combined with the already-explained lack of weight limit.) While there are many business travelers going to and from Cebu City, the routes on which these travelers are typically traveling are already well-served by several high-end airlines that also offer onward connections to Europe and the Americas (e.g. Cathay Pacific to Hong Kong, Korean Air and Asiana to Seoul, Japan Airlines to Tokyo, Emirates to Dubai, EVA to Taipei.) Additionally, Philippine Airlines also already competes in that space (in addition to apparently offering direct flights from Cebu to LAX now, which I think is a rather recent development.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With their low-cost model and lack of alliance partners for onward connections, it would be difficult for Cebu Pacific to compete for the already well-served premium-cabin demand in Cebu. Instead, their business model is catered to serving Filipinos traveling between islands and to regional destinations where lots of Filipinos work out-of-country. Last I heard, approximately 10,000,000 Filipinos worked outside the Philippines (around 10% of their total population,) so serving that demographic is not a small market. In case it's not obvious, this is an extremely price-sensitive demographic which is well-served by Cebu Pacific's low-cost model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should probably also be noted that, while 436 passengers on an A330 is unique to Cebu Pacific, high-density economy-only configurations in general aren't. Lots of regional-service low-cost carriers offer high-density economy-only fleets, even in less cost-sensitive areas like Europe, Canada, and the U.S. In Cebu Pacific's own region, &lt;a href=&quot;http://www.seatguru.com/airlines/Air_Asia/Air_Asia_Airbus_320.php&quot; rel=&quot;noreferrer&quot;&gt;AirAsia&lt;/a&gt; and &lt;a href=&quot;http://www.seatguru.com/airlines/Tiger_Airways/Tiger_Airways_A320.php&quot; rel=&quot;noreferrer&quot;&gt;Tigerair&lt;/a&gt; also operate similar high-density, economy-only fleets targeting the same demographic (though, admittedly, &lt;a href=&quot;http://www.seatguru.com/airlines/AirAsia_X/AirAsia_X_Airbus_A330-300.php&quot; rel=&quot;noreferrer&quot;&gt;AirAsia X does have 2 rows of business-class seats in their A330s&lt;/a&gt;, but these are on longer routes than Cebu Pacific normally serves, e.g. Singapore-Australia.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2016-04-28T15:56:46.240" LastActivityDate="2016-04-28T15:56:46.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17463" PostTypeId="1" CreationDate="2015-07-31T22:14:10.843" Score="2" ViewCount="191" Body="&lt;p&gt;first time here so bear with me please.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it looks to me like there are A LOT of small plane crashes.  Pretty much every week a couple of people die in small planes, at least.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this due to the planes themselves, to the pilots, to the bad maintenance on the planes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Main reason I ask, I'd like to learn (maybe, just maybe) how to fly, or at least try a class once, but I'm very afraid of those small planes statistics.  Are there any websites or similar that explain why so many accidents on those and the reasons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I asked, can't really start learning with a bigger plane with &quot;real engines&quot; :-)&lt;/p&gt;&#xA;" OwnerUserId="9624" LastActivityDate="2015-07-31T22:14:10.843" Title="How dangerous are small planes?" Tags="&lt;accident-statistics&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2015-08-01T01:04:28.330" ContentLicense="CC BY-SA 3.0" />
  <row Id="17464" PostTypeId="2" ParentId="17437" CreationDate="2015-07-31T22:58:44.927" Score="10" Body="&lt;p&gt;This was a test aimed at measuring the effect of feathered wingtips. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Stemme_S10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stemme S-10&lt;/a&gt; has a four-part wing, and for the experiment the outer wing panels were removed and replaced by five staggered small wings, as shown on the picture in your question. This reduces wingspan from 23&amp;nbsp;m to only 11.4&amp;nbsp;m plus the span of the wingtips, in total maybe 14&amp;nbsp;m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://jeb.biologists.org/content/198/3/775.full.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;feathered wingtip&lt;/a&gt; shows less induced drag than a straight wing of identical span, similar to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;winglet&lt;/a&gt;, because it can involve a bigger mass of air into the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;creation of lift&lt;/a&gt;. But it cannot perform wonders, the effect is small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept behind this experiment is called &quot;winggrid&quot; and the brainchild of Dr. U. La Roche. See &lt;a href=&quot;http://www.allstar.fiu.edu/aero/winggrid.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for one of the few still active sites on the topic - the original site &lt;a href=&quot;http://www.winggrid.ch&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.winggrid.ch&lt;/a&gt; has long been abandoned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sad fact: This aircraft was destroyed in a &lt;a href=&quot;http://aviation-safety.net/wikibase/wiki.php?id=58893&quot; rel=&quot;nofollow noreferrer&quot;&gt;mid-air collision in 2007&lt;/a&gt;. At that time, it had been reverted to the original wingtips.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-29T21:09:13.990" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17465" PostTypeId="1" AcceptedAnswerId="17466" CreationDate="2015-07-31T23:20:41.523" Score="13" ViewCount="2260" Body="&lt;p&gt;I'm having an argument regarding elevator trim. According to a book my friend showed me, trim is for constant airspeed. So, let's say we are flying level at 100 kts with 2300 RPM and it's trimmed. My buddy claims that if we reduce power (1800 rpm for example), and do not touch elevator trim and yoke, pitch will be set for 100 kts by airplane itself and we can descend at 100 kts with 1800 rpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what I think is to maintain 100 kts with reduced power, the nose of airplane should be lowered and forward trim should be readjusted by a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can somebody give me an answer to end this argument?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="19" LastEditDate="2017-03-02T16:23:33.947" LastActivityDate="2017-03-02T16:23:33.947" Title="What is the relation between trim setting and constant airspeed?" Tags="&lt;trim&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17466" PostTypeId="2" ParentId="17465" CreationDate="2015-07-31T23:49:15.157" Score="19" Body="&lt;p&gt;Your friend is right.  Elevator trim isn't setting a pitch, it is compensating for control forces on the elevator, which vary with speed.  If you are trimmed for level flight at 100 kias and reduce power the plane will initially slow.  As it slows the trim will cause a nose-down moment causing the plane to pitch down.  Given no input, the plane will equilibrate at whatever nose-down pitch is needed to regain the forces it was trimmed for, which means speeding back up to 100 kias. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are correct that to maintain 100 kias with reduced power the nose should be lowered, but the trim will take care of that for you.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might have a misconception about how trim works, based on your argument.  A typical trim setup in light airplanes is essentially another control surface on the elevator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5grws.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5grws.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The elevator is the large control surface and that smaller control surface is the elevator trim.  When you adjust the pitch trim you are adjusting this trim tab which provides a force on the elevator that counters aerodynamic forces.  This is why the airplane responds in pitch to maintain constant aerodynamic forces (e.g. constant indicated airspeed) for a given trim setting.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You can test this in the airplane easily.  Take your plane up to the altitude you practice maneuvers at, set 75% power (or some other number) and trim for straight and level.  Add power and watch the plane climb, decrease power and watch it descent, both without touching the trim.  Go back to straight and level and trimmed and accelerate without climbing -- note you are having to retrim as your speed increases.  Decelerate without descending  -- note you are retrimming as your speed decreases.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-07-31T23:54:48.967" LastActivityDate="2015-07-31T23:54:48.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17468" PostTypeId="2" ParentId="9760" CreationDate="2015-08-01T00:14:40.217" Score="1" Body="&lt;p&gt;BAE according to the accounts of a local Aircraft Engineer stood for &quot;Bring Another Engine&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine reliability is was really was the death of this aircraft. At least in my friends experience. Their local examples were constantly having to be taken off line due to hangar time.&lt;/p&gt;&#xA;" OwnerUserId="9626" LastActivityDate="2015-08-01T00:14:40.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17469" PostTypeId="1" AcceptedAnswerId="17491" CreationDate="2015-08-01T03:42:41.573" Score="6" ViewCount="1360" Body="&lt;p&gt;Let's say I'm flying some business types in a Gulfstream III (an approach category C aircraft) from Stockton to Palmdale to meet up with some USAF types there (new airplane deal, wooo!).  Can I accept/fly the HI-ILS approach to RWY 25 at KPMD:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/lLMy5.jpg&quot; alt=&quot;KPMD HI-ILS or LOC/DME RWY 25 approach plate[1]&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or am I only allowed to accept a STAR or vectors to a standard ILS approach to KPMD?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="22726" LastEditDate="2019-10-23T23:07:50.357" LastActivityDate="2019-10-23T23:07:50.357" Title="Can civil pilots *ever* fly military high-altitude penetration approach procedures?" Tags="&lt;iaps&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17471" PostTypeId="1" AcceptedAnswerId="17475" CreationDate="2015-08-01T04:08:10.890" Score="2" ViewCount="184" Body="&lt;p&gt;I noticed an interesting note -- circled in red pencil below -- on the KEEO RNAV (GPS) RWY 03 approach the other day:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VWQUW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VWQUW.jpg&quot; alt=&quot;KEEO RNAV (GPS) RWY 3 approach plate with the &amp;quot;Descent Angle NA&amp;quot; note circled in red&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would the FAA apparently prohibit constant-descent final approaches to this airport, given the operational benefits they provide to aircraft of many types? (While props can get away with a lot more on approach than a jet can -- diving and driving is still more workload than maintaining a constant descent.)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-08-01T07:42:36.273" Title="Non-precision approaches for which constant descents are not approved?" Tags="&lt;iaps&gt;&lt;terps&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17472" PostTypeId="1" CreationDate="2015-08-01T05:28:03.063" Score="6" ViewCount="761" Body="&lt;p&gt;Mounted on top of each JU 52 engine is a translucent tube and a dial (see images).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the purpose of the tube and what does it measure?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the dial measure (oil or fuel) flow or quantity?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are these indicators visible at night?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WUpEy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WUpEy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9629" LastEditorUserId="19" LastEditDate="2016-07-08T09:51:03.593" LastActivityDate="2016-07-08T09:51:03.593" Title="What is the purpose of the translucent tube and dial on JU 52 engine nacelle?" Tags="&lt;engine&gt;&lt;nacelle&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17474" PostTypeId="1" CreationDate="2015-08-01T07:09:14.060" Score="4" ViewCount="709" Body="&lt;p&gt;I know that the empennage is the tail section of the aircraft and includes the horizontal and vertical stabilisers. But what is the empennage height? Is it the height of the horizontal stabiliser from the ground or is it the height of the vertical stabiliser?&lt;/p&gt;&#xA;" OwnerUserId="7653" LastActivityDate="2015-08-27T14:36:45.263" Title="What is meant by empennage height?" Tags="&lt;aircraft-design&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17475" PostTypeId="2" ParentId="17471" CreationDate="2015-08-01T07:29:09.467" Score="2" Body="&lt;p&gt;Probably because it's so shallow: you have 8+ NM to descend about 1100'. On a 3 degree angle, you'd typically decsend 1100' in a little over 3 miles.  I'll leave it to good folks with calculators to work out exactly what angle this would be, but it's under 1.5 degrees, so probably below whatever limit TERPS gives for depicting an angle there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One solution would be to remain at the FAF altitude until reaching a calculated &quot;fly-off&quot; point, at which time you would descend at a 3 degree angle until reaching published MDA + 50', at which point you continue or go around.  But that probably takes specific FMC software &amp;amp; perhaps a tailored approach chart, so with only this one your option pretty much looks to be &quot;dive&quot; (not that far) &quot;and drive&quot; (quite a bit).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though that gets you to an MDA that is 1700'+ above the TDZE...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACTUALLY, ON FURTHER CONSIDERATION: It isn't too shallow, it's a &lt;strong&gt;steep&lt;/strong&gt; path from FAF to TDZE, 3000' in 8 NM (would be 9NM at 3 degrees). And the angle to do that probably doesn't quite clear the WAGOK step-down, meaning your vertical path becomes even steeper at that point than it starts out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So rather than publish gradient***s*** steeper than (whatever the TERPS limit is), and increasing after the step-down fix, they just say NA &amp;amp; let you &quot;make it work&quot; on your own. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I notice that there is no &lt;a href=&quot;https://aviation.stackexchange.com/questions/17350/why-is-vdp-is-not-authorized&quot;&gt;VDP&lt;/a&gt; published here, either...&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-01T07:42:36.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17478" PostTypeId="2" ParentId="17472" CreationDate="2015-08-01T08:32:45.943" Score="2" Body="&lt;p&gt;My Google foo fails me, but I did &lt;a href=&quot;http://www.koppmeier.de/_webgall/_public/Ju52/slides/DSC_4152_en.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;find this picture&lt;/a&gt; with a caption stating that it's a fuel gauge.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Zooming in on the image suggests that this is plausible&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also found this &lt;a href=&quot;http://forum.axishistory.com/viewtopic.php?f=69&amp;amp;t=182771&amp;amp;start=15#p1638870&quot; rel=&quot;nofollow noreferrer&quot;&gt;diagram of the wing fuel storage&lt;/a&gt; which shows the gauge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To read it at night, pilots would use a flashlight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5p7bg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5p7bg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find any authoratative source.  If I do, I'll come back and edit.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1961" LastEditDate="2015-08-02T08:31:16.110" LastActivityDate="2015-08-02T08:31:16.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17479" PostTypeId="1" CreationDate="2015-08-01T08:55:34.547" Score="0" ViewCount="84" Body="&lt;p&gt;Here's a totally hypothetical question that came up in a discussion with friends:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a commercial aircraft (say, an Airbus A320) was &quot;dropped&quot; from a typical cruising altitude (say, 35,000ft) with a current ground speed of zero and all engines off, would it be possible to get it into gliding by putting the nose down, and how far could it go? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The much more practical question &quot;how far can an aircraft glide&quot; is already answered (e.g.,&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2999/how-far-can-airplanes-glide&quot;&gt;How far can airplanes glide?&lt;/a&gt;), but it would be great if somebody could participate in this thought experiment with no engines &lt;em&gt;and&lt;/em&gt; no initial speed. &lt;/p&gt;&#xA;" OwnerUserId="9634" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-01T08:55:34.547" Title="Thought experiment: can an aircraft that is dropped from the sky get into gliding?" Tags="&lt;aerodynamics&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-08-01T14:09:19.507" ContentLicense="CC BY-SA 3.0" />
  <row Id="17480" PostTypeId="1" CreationDate="2015-08-01T09:34:13.040" Score="19" ViewCount="1763" Body="&lt;p&gt;I was reading the book &lt;em&gt;Vulcan 607&lt;/em&gt; by Rowland White who examines the details of a British bomber's mission during the Falklands War in 1982. At some point, the author wrote about the fuel shortage experienced by the crew of the four-engine Vulcan bomber during their return to their base. The author wrote that the pilot &quot;considered shutting down one of the four Rolls-Royce Conway engines to get a little more range out of the remaining fuel...&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not heard of this type of procedure before, so I am wondering if the decision to shut down one of the engines to maximize fuel efficiency makes sense.&lt;/p&gt;&#xA;" OwnerUserId="9635" LastEditorUserId="15982" LastEditDate="2017-05-25T10:10:15.983" LastActivityDate="2019-10-31T03:45:27.700" Title="Can a four-engine aircraft with limited fuel gain extra range by shutting down one of its engines?" Tags="&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17484" PostTypeId="2" ParentId="17469" CreationDate="2015-08-01T11:48:20.190" Score="2" Body="&lt;p&gt;Might check what descent rates would be required before trying it with passengers, but there shouldn't be any reason in principle that ATC couldn't clear you for that version of the ILS there.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-08-01T11:48:20.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17485" PostTypeId="1" AcceptedAnswerId="21527" CreationDate="2015-08-01T12:08:55.250" Score="4" ViewCount="1379" Body="&lt;p&gt;I was looking at this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/2/25/Two_F-22A_Raptor_in_column_flight_-_%28Noise_reduced%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CpA8P.jpg&quot; alt=&quot;F-22&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and couldn't help notice that the RAM coating looks different on the vertical/horizontal stabilizers and wings compared to the fuselage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the fact that there are different types of RAM, such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar-absorbent_material#Iron_ball_paint_absorber&quot; rel=&quot;nofollow noreferrer&quot;&gt;iron ball paint absorber&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar-absorbent_material#Foam_absorber&quot; rel=&quot;nofollow noreferrer&quot;&gt;foam absorber&lt;/a&gt;, etc... Are different types of RAMs being used in order to achieve stealth? &lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="3201" LastEditDate="2015-10-04T10:49:00.707" LastActivityDate="2015-10-06T21:13:25.730" Title="Do designers use the same RAM (Radar Absorbing Material) coating across the length and breadth of a fighter aircraft?" Tags="&lt;radar&gt;&lt;stealth&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17486" PostTypeId="2" ParentId="17480" CreationDate="2015-08-01T12:12:24.347" Score="11" Body="&lt;p&gt;Assuming the aircraft is always flying at its optimal Lift/Drag ratio (= optimal angle of attack = optimal speed for a given weight and altitude), then the question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Is it more efficient to generate a given amount of thrust &lt;strong&gt;T&lt;/strong&gt; with 4 engines x &lt;strong&gt;T/4&lt;/strong&gt;, or 3 engines x &lt;strong&gt;T/3&lt;/strong&gt;?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think that in the general case, it is not the case. Specific Fuel Consumption tends to increase with thrust (at constant speed):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wCzRD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wCzRD.jpg&quot; alt=&quot;SFC vs thrust&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; the above diagram is for &lt;strong&gt;Turbofans&lt;/strong&gt; (Source: Airplane Aerodynamics and Performance, Roskam). It would be interesting to have similar trends for other types of engines (turboprops, turbojets, piston engines), but I could not find any!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, it is possible that, in this particular case, the engines were simply working too far off their design point, so increasing thrust &lt;em&gt;was&lt;/em&gt; improving their SFC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there is a problem with cutting one engine: The pilot will need to counteract the thrust asymmetry with the rudder, and this will have a significant cost in drag. Of course, the pilot could just cut 2 engines instead of one! :-)&lt;/p&gt;&#xA;" OwnerUserId="9059" LastEditorUserId="22726" LastEditDate="2019-10-31T02:48:04.717" LastActivityDate="2019-10-31T02:48:04.717" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="17490" PostTypeId="2" ParentId="17406" CreationDate="2015-08-01T19:07:34.027" Score="1" Body="&lt;p&gt;I'd say vertical takeoff in a non-rotating wing, not deflected thrust machine was obtained in the Custer Channel Wing models, you have some videos in YouTube &lt;a href=&quot;https://youtu.be/-Sn5JL9t_C4&quot; rel=&quot;nofollow&quot;&gt;https://youtu.be/-Sn5JL9t_C4&lt;/a&gt;  &lt;a href=&quot;http://www.flightglobal.com/pdfarchive/view/1952/1952%20-%200044.html&quot; rel=&quot;nofollow&quot;&gt;http://www.flightglobal.com/pdfarchive/view/1952/1952%20-%200044.html&lt;/a&gt; &lt;a href=&quot;http://www.angelfire.com/va3/bythefire/&quot; rel=&quot;nofollow&quot;&gt;http://www.angelfire.com/va3/bythefire/&lt;/a&gt;&#xA;NASA Technical Report Server -NTRS- has a L53A09 full size wind tunnel report of this arrangement &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930087470.pdf&quot; rel=&quot;nofollow&quot;&gt;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930087470.pdf&lt;/a&gt;&#xA;   and links to the Custer follower's sites exist in Wikipedia&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2015-08-01T19:07:34.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17491" PostTypeId="2" ParentId="17469" CreationDate="2015-08-01T19:55:19.853" Score="4" Body="&lt;p&gt;As long as you can actually make the altitude restrictions, then yes, there's no reason why you cannot request to fly the approach.  However, as a general courtesy, you should also factor in your approach speed.  ATC might not appreciate a Cessna clobbering the approach 34 miles out.  These approaches are typically flown at 250+kts, so just keep that in mind.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-08-01T20:02:36.387" LastActivityDate="2015-08-01T20:02:36.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17492" PostTypeId="1" AcceptedAnswerId="17547" CreationDate="2015-08-01T20:07:44.067" Score="9" ViewCount="390" Body="&lt;p&gt;I've been taught that when I'm on final approach to land, I should pick a feature or landmark that's some distance along the extended centre-line, so that when I'm close enough to the ground that I can't properly see the runway edges any more, I can still look forwards and check my heading against this landmark. This is necessary on aircraft without flaps where the nose (the engine cowling) restricts the pilot's view of the runway in the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The view along the runway changes completely from circuit height to runway level, and it's not obvious which features will be visible from less than 100 ft height. At my home aerodrome, it's easy to learn which feature to line up on, because I've seen them all before many times. When I'm landing at a new aerodrome, how can I select a feature to line up and be reasonably confident that it's still visually obvious all the way through the landing?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-08-03T19:49:42.850" Title="How do you choose a feature to line up on when approaching to land?" Tags="&lt;visual-approaches&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17493" PostTypeId="2" ParentId="17406" CreationDate="2015-08-01T21:12:38.103" Score="4" Body="&lt;p&gt;Maybe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would need a very special kind of wing, one which controls the flow direction at the trailing edge by blowing. Such a concept had been tested by &lt;a href=&quot;https://www.avinc.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;AeroVironment&lt;/a&gt; in the 1980s and in a model, but to my knowledge no man-carrying airplane using this concept exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cross section of the wing's airfoil is a circle, with an exhaust slot at the back. The exhaust stream of a gas turbine is channeled through the tubular spar of the wing and exits through a spanwise slot in a collar around the spar. By rotating the position of the slot and pumping enough air through it, you can control the amount of &lt;a href=&quot;https://en.wikipedia.org/wiki/Circulation_(fluid_dynamics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;circulation&lt;/a&gt; this wing creates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1hooT.png&quot; alt=&quot;Cross section through tubular wing with rotating exhaust&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exhaust position of the inboard wing can be used to control lift, like flaps do on a &quot;normal&quot; wing, and the outer part takes over the function of ailerons. By pointing the exhaust straight down and with a sufficient air mass flow, this wing can indeed take off vertically. Efficiency will be nothing to write home about, however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A blown flap in the conventional sense needs external flow, because its own mass flow is far too small to create sufficient lift. All it does is to invigorate an old, spent boundary layer, so it will stay attached over the contour downstream of the blowing point. Without speed, no external flow exists which could be influenced, except for a small quantity dragged along by the airstream of the blown flap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar, albeit less radical, idea was used in the British research airplane &lt;a href=&quot;https://en.wikipedia.org/wiki/Hunting_H.126&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hunting 126&lt;/a&gt;. It used the exhaust gasses from its fuselage-mounted Orpheus engine to blow air over its flaps. Additionally, it had small nozzles at the end of the fuselage and the wing tips for low-speed control, just like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Harrier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Harrier Jump Jet&lt;/a&gt;. However, it needed some forward speed to create enough lift to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f5SkT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f5SkT.jpg&quot; alt=&quot;Hunting 126 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hunting 126 in flight (picture &lt;a href=&quot;http://1000aircraftphotos.com/Contributions/Visschedijk/6897.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-18T17:54:34.030" LastActivityDate="2015-08-18T17:54:34.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17494" PostTypeId="2" ParentId="17492" CreationDate="2015-08-01T22:31:01.590" Score="0" Body="&lt;p&gt;Dan Hulme's technique is basically the same as mine.  Keep that reference point in view at a point along an imaginary horizontal line which crosses your windscreen, controlling that position with right-left heading changes to compensate for wind.  When getting to near-touchdown altitude you can generally see out to the the side if you are more-or-less equidistant from the edges of the runway, which helps keep you on or near the centerline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just make sure that your initial visual &quot;reference point&quot; isn't a moving object, such as a cloud, a truck on the freeway... or another airplane in the sky!  &lt;/p&gt;&#xA;" OwnerUserId="9606" LastActivityDate="2015-08-01T22:31:01.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17495" PostTypeId="1" AcceptedAnswerId="17530" CreationDate="2015-08-02T02:30:45.447" Score="6" ViewCount="4720" Body="&lt;p&gt;At my home airport, we do the run-up on the ramp, but I guess each airport has its own preference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the &quot;standard&quot; run-up location? If I recall from my training early on, you can do it at the runway if you angle yourself against the departure end. If this is correct, how do I know that I've angled myself in a way not to blow any debris into an aircraft behind me. And if I do the run-up at the end of the runway, don't I risk obstructing an aircraft that wants to takeoff behind me but has to wait for me to do the runup?&lt;/p&gt;&#xA;" OwnerUserId="9418" LastEditorUserId="19" LastEditDate="2017-09-19T15:54:57.963" LastActivityDate="2017-09-19T17:34:12.900" Title="Where to do the Run-up and Safety on the Return Flight?" Tags="&lt;airport&gt;&lt;preflight&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17497" PostTypeId="1" AcceptedAnswerId="17499" CreationDate="2015-08-02T05:48:38.377" Score="6" ViewCount="427" Body="&lt;p&gt;There is a widespread belief, at least within Australia, that Qantas has, or had, an above-average safety record. For example, AirlineRatings.com recently listed Qantas as the world's safest airline, which was reported on by the &lt;a href=&quot;http://www.abc.net.au/news/2015-01-07/qantas-tops-airline-safety-rankings/6005074&quot; rel=&quot;nofollow&quot;&gt;Australian Broadcasting Corporation&lt;/a&gt; and &lt;a href=&quot;http://www.traveller.com.au/setting-extraordinary-records-of-firsts-qantas-named-worlds-safest-airline-12j64t?promote_channel=edmail&amp;amp;mbnr=MzgxNjcxNQ&quot; rel=&quot;nofollow&quot;&gt;Fairfax Media&lt;/a&gt;. Personally speaking, it seems like aircraft incidents with Qantas or JetStar get more coverage than those involving other airlines, but I can't verify that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I'm skeptical of the belief that Qantas has an above-average safety record, let alone being the safest airline in the world.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Wikipedia article &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Qantas_fatal_accidents&quot; rel=&quot;nofollow&quot;&gt;List of Qantas fatal accidents&lt;/a&gt;, I know that Qantas hasn't had any fatal jet airliner incidents, and the last accident it had was in 1951. However, I don't know whether aircraft accidents are so rare that an airline can have a better average than others because of chance alone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not doubting that some countries have safer airlines than others. If offered the choice between Qantas and Air Koryo, I'd definitely choose the former. I also don't doubt that some countries are safer to fly in than others - for example, planes in Australia don't have to deal with snow very often. However, I don't expect that to be a major factor. So I'm ultimately interested in a comparison between Qantas and airlines from countries that are comparable to Australia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did Qantas have a perception of having an extraordinary safety record before the 1988 movie &lt;a href=&quot;http://www.imdb.com/title/tt0095953/quotes&quot; rel=&quot;nofollow&quot;&gt;Rain Man&lt;/a&gt;, where the titular character said that Qantas never crashed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there enough data to say that Qantas is the safest airline in the world, or even say that it's safer than similar airlines, such as the ones Raymond refused to get on in the movie?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2250" LastEditorUserId="790" LastEditDate="2015-08-02T08:29:55.140" LastActivityDate="2015-08-02T10:01:26.430" Title="Does Qantas have an above-average safety record?" Tags="&lt;safety&gt;&lt;airlines&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-08-02T11:25:57.847" ContentLicense="CC BY-SA 3.0" />
  <row Id="17498" PostTypeId="1" CreationDate="2015-08-02T06:14:26.407" Score="4" ViewCount="677" Body="&lt;p&gt;The &lt;a href=&quot;https://www.youtube.com/watch?v=dkLWD2Y6TAQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Falling Leaf maneuver&lt;/a&gt; is a way to lose altitude by descending like a tree leaf. Is this maneuver used in the recovery of UAVs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/KmDrG.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.simonwil.com/slipping-and-the-falling-leaf/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9642" LastEditorUserId="39" LastEditDate="2016-11-18T00:46:54.193" LastActivityDate="2016-11-18T00:46:54.193" Title="Is the Falling Leaf maneuver used for UAV recovery?" Tags="&lt;flight-controls&gt;&lt;unmanned-aerial-vehicle&gt;&lt;stability&gt;&lt;maneuver&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17499" PostTypeId="2" ParentId="17497" CreationDate="2015-08-02T08:07:33.117" Score="7" Body="&lt;h2&gt;Defining and Measuring 'Safety'&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These ranking depends how you define safety. Here is your problem: You can easily do this by widely publicised facts, such as well documented fatal accidents. Fatal accidents occur much much too seldom to with any statistical confidence to say how safe an airline is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you would much rather do is go by accidents and incidents (the little things that occur everyday and give you a feeling for how stuff is done and handled). For instance: hydraulic leaks, loss of separation to other aircraft or electrical problems prompting a return. A small selection of these are reported on the popular site &lt;a href=&quot;http://avherald.com&quot;&gt;Aviation Herald&lt;/a&gt;, but this is (emphasis) only a small subset that happen to come through. Some western countries with the objectively the best safety are over-reported since they are just better at documenting. You'll find heaps of entries on 'fume events' on Airbus aircraft from Germany for instance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are considerably harder to collect, since how they are classified and reported changes by country and aviation agency. Some publish for common good, other ones barely collect them. For this reason, the way these 'rankings' do it is by fatal accidents and other easy to get parameters. This is eventually what comes through to newspaper sites with little detail on how they were put together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The parameters measured by AirlineReports:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the airline IOSA certified?&lt;/li&gt;&#xA;&lt;li&gt;Is the airline on the European Union (EU) Blacklist?&lt;/li&gt;&#xA;&lt;li&gt;Has the airline maintained a fatality free record for the past 10 years? &lt;/li&gt;&#xA;&lt;li&gt;Is the airline FAA endorsed?&lt;/li&gt;&#xA;&lt;li&gt;Does the country of airline origin meet all 8 ICAO safety parameters?&lt;/li&gt;&#xA;&lt;li&gt;Has the airline's fleet been grounded by the country's governing aviation safety authority due to safety concerns?&lt;/li&gt;&#xA;&lt;li&gt;Does the airline operate only Russian built aircraft?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Most of these are bare minimums that can be expected from an airline, but do not really go to any distance to show who stands out. For any more detailed sense and purposes (how media are using it), I'd call this useless.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Also note that this does not include the liability question for fatal accidents- who was at fault? You can finally also (albeit unlikely) have a completely safe airline that does not have a single certification.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Qantas&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Qantas has had two very serious incidents with a Boeing 747 and A380. They also had a serious incident on involving &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_72&quot;&gt;A330 losing altitude&lt;/a&gt;. This does not really IMHO award them as the 'safest airline' for the past few years, since this is considerably more than a lot of other airlines have experienced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for all practical sense and purposes, they are as safe as any other airline. The chances of anything happening are just so incredibly remote that it's not worth the trouble of thinking about it. Getting a connecting flight to fly with another airline will probably be less safe than just flying them directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the maintenance matters, Qantas owns JetStar and they appear to use the same maintenance facility for their aircraft. A further difference is the training where there appear to be overlaps as well, so there are only small differences on perhaps the most important parameters differing the two.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-02T10:01:26.430" LastActivityDate="2015-08-02T10:01:26.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17500" PostTypeId="2" ParentId="17472" CreationDate="2015-08-02T09:19:48.820" Score="5" Body="&lt;h2&gt;This is the Fuel Gauge.&lt;/h2&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Direkt auf der Triebwerksgondel sind bei der Ju 52/3m die Treibstoffanzeigen montiert&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;The fuel guage is mounted directly on the engine pylons on the Ju 52/3m.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.austrianwings.info/2009/02/ein-flug-in-der-tante-ju/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AustrianWings&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is suggested that the indicator gives a reading in hundreds of liters (&lt;em&gt;Liter x 100&lt;/em&gt; written underneath).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NaDb4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NaDb4.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.planepics.org/cms/index.php/ju-52e&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Visible on the illustration below as Kraftstoffuhr (&lt;em&gt;'Fuel Clock'&lt;/em&gt;).&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i63.servimg.com/u/f63/12/53/99/65/ju-52_11.jpg&quot; alt=&quot;pic&quot; /&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-06T05:54:43.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17502" PostTypeId="1" AcceptedAnswerId="17506" CreationDate="2015-08-02T14:15:28.177" Score="3" ViewCount="4670" Body="&lt;p&gt;Sometimes fixes found on approach plates are labeled &lt;strong&gt;radar&lt;/strong&gt;. What are these radar fixes and how to they differ from fixes usually found on approaches?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IYrgt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IYrgt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1968" LastEditDate="2015-08-02T18:29:01.097" LastActivityDate="2015-08-02T20:58:10.813" Title="What is a radar fix?" Tags="&lt;navigation&gt;&lt;approach&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17503" PostTypeId="1" AcceptedAnswerId="17544" CreationDate="2015-08-02T16:17:04.447" Score="12" ViewCount="12000" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WtYWY.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WtYWY.gif&quot; alt=&quot;Great circle route between Sydney (SYD) &amp;amp; Dallas (DFW).&quot;&gt;&lt;/a&gt;&#xA;Route For &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flights_7_and_8&quot; rel=&quot;noreferrer&quot;&gt;Qantas 7&amp;amp;8&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As this route shows, once the flight exits SYD, then all it has nearby is just the great pacific ocean. In such a situation, if it hits some emergency, what all options would it have, if it wants to land, due to some emergency like a patient on board?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="5517" LastEditDate="2015-08-05T18:15:19.180" LastActivityDate="2015-08-05T18:15:19.180" Title="What options would Qantas Flights 7/8 have in case of emergency?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;airbus-a380&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17504" PostTypeId="1" AcceptedAnswerId="17505" CreationDate="2015-08-02T16:54:46.347" Score="30" ViewCount="20900" Body="&lt;p&gt;Right now if an airliner wants to fly a really long distance (eg., a Boeing 787 flying from Seattle to Tokyo), it has to load itself down with lots and lots of fuel, which in turn weighs thousands and thousands of pounds.  This, of course, makes the flight of the aircraft less efficient than it could be&lt;sup&gt;1&lt;/sup&gt;.  Thus, if the craft could theoretically carry half as much fuel, that should increase the fuel efficiency of the craft, right?&lt;sup&gt;2&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mid-way refueling seems like it would be a &lt;em&gt;Good Idea&lt;/em&gt;™ at that point.  Of course, landing would add a heck of a lot of time to the flight, so it seems the better option would be mid-air refueling.  It would allow for the aircraft to be more efficient, without the need for stopping on a long journey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing and Airbus both make &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot; rel=&quot;nofollow noreferrer&quot;&gt;a few airplanes&lt;/a&gt; | &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A400M_Atlas&quot; rel=&quot;nofollow noreferrer&quot;&gt;that can do&lt;/a&gt; | &lt;a href=&quot;https://www.youtube.com/watch?v=8IauN-Bv0tY&quot; rel=&quot;nofollow noreferrer&quot;&gt;mid-air refueling&lt;/a&gt;, in fact one of them is a highly modified 747-200 (properly called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_VC-25&quot; rel=&quot;nofollow noreferrer&quot;&gt;VC-25&lt;/a&gt;) used as Air Force One:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AeeuI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AeeuI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://chivethebrigade.files.wordpress.com/2011/07/photo-day-07_28_11-0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wordpress.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that, because Airbus and Boeing's engineers and sales managers are really quite smart, they have a really good reason that they don't fit/sell this feature on any civilian transportation aircraft.  But I'm not sure what that reason is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know why airlines do not use aircraft that are capable of mid-air refueling?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;em&gt;If I'm not mistaken, increased weight means an increased AoA to maintain level flight, which in turn increases induced drag from the wing.  Less fuel would mean less induced drag or, if mid-air refueling were common practice, a wing that was designed to be more efficient because it was required to handle less weight.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; &lt;em&gt;I don't know by how much, if it's not that much, well, that might explain why nobody does this.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="8282" LastEditDate="2019-04-02T20:50:47.130" LastActivityDate="2019-12-24T06:46:53.473" Title="Why don't airliners use in-air refueling systems?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;refueling&gt;&lt;mid-air-refueling&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="17505" PostTypeId="2" ParentId="17504" CreationDate="2015-08-02T17:02:15.597" Score="56" Body="&lt;p&gt;&lt;strong&gt;Fuel Quantity&lt;/strong&gt; Unlike smaller fighter jets, you would need to offload a substantial quantity of fuel. For a B777, you're looking in the range of 60 tonnes of fuel for half a tank. The boom of a KC-135 (faster than a basket) can do around 3 tonnes a minute. The math comes to then 20 minutes of aerial refuelling. The KC-46 can do perhaps 180 tonnes, so you might squeeze out three refuelling operations from one flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Risk&lt;/strong&gt; This is considerably more dangerous than the very conservative safety margins aircraft normally operate within. You would have one aircraft filled to the brim with fuel, and another aircraft with 300+ passengers. A quick search on YouTube is enough to propose this entire thing is very dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, you need to consider that the aircraft needs safety margin to divert should refuelling not work, which cuts into the benefits you can expect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many intercontinental routes will be flown at night, making the manoeuvre more difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Refuelling Area&lt;/strong&gt; Looking at the route you proposed, the closest airfield would probably be in Alaska, at least 500km away. Guess another relevant area would be Iceland/Greenland. Even if you did reroute, you'd get away from the jetstreams that aircraft over the Pacific use lying considerably further south, reducing efficiency. The same scenario applies for eastbound Atlantic flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Expensive&lt;/strong&gt; You would need to get another aircraft (~$200m for a KC-46) with special equipment and crew training. The receiving aircraft crew would also  need special training. The airframe modifications would be complicated and require certification. Furthermore, you would need to get everybody to agree on some common standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Logistics&lt;/strong&gt; Planning is difficult. Each aircraft would have to be rerouted to intercept the tanker at a certain time and place. You want to refuel them perfectly one after an other, which is almost certainly not possible. There's just not the volume of aircraft movements feasible for this, especially for the ultra-long flights where it may have the greatest benefit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Other Landing Benefits&lt;/strong&gt; &#xA;Include changing crews and possibly offloading passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Applicability&lt;/strong&gt;&#xA;The number of flights where this can be practically implemented and used is very limited and for all intents and purposes, you can just land the plane itself and refuel it. Even for the route you propose, it's around 7,500 km which is not a lot for a B777.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-03T13:38:55.833" LastActivityDate="2015-08-03T13:38:55.833" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="17506" PostTypeId="2" ParentId="17502" CreationDate="2015-08-02T18:24:49.020" Score="4" Body="&lt;p&gt;Since this an FAA instrument approach procedure, this answer is specific to the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;RADAR&lt;/strong&gt; label indicates that these fixes are marked on the approach controller's screen and he/she can advise the pilot when the aircraft is over the fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of Radar for arrivals and approaches is outlined in &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA JO 7110.65&lt;/a&gt;, Chapter 5, Sections 9 and 10. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.19F.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Order 8260.19&lt;/a&gt;, paragraph 8-2-5(a) states that &quot;Radar vectoring may be provided through any approach segment up to and including the final approach fix.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll note that the approach plate does NOT indicate &lt;strong&gt;RADAR REQUIRED&lt;/strong&gt; because it is not the only method of determining or defining the fixes. In this particular approach, arrival at a fix can be determined THREE different ways: with Radar, LOC with DME (or GPS lieu of DME), and LOC with VOR radial. Per 8260.19, paragraph 8-6-6h, all IFR aircraft are assumed to have at least one VOR receiver, thus no equipment requirement note is required for this particular approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, I've found that ATC will not call out crossing a fix unless you specifically request the service, though they will usually identify your position prior to hand-off (e.g. November 1234, two miles from SHAGY, contact tower on 120.5).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-08-02T20:58:10.813" LastActivityDate="2015-08-02T20:58:10.813" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17507" PostTypeId="1" CreationDate="2015-08-02T20:08:00.757" Score="3" ViewCount="509" Body="&lt;p&gt;The other week my flight was overbooked and so the airline looked for volunteers to take another flight the following morning. I can't stop thinking about this since the number of seats available and sold should've been known to the airline for quite some time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone claimed that airlines expect a number of passengers to rebook or not show up and thus with purpose overbook sometimes. Can this really be true? Or is it a data consistency thing where availability for ticket booking is prioritized? Or was it perhaps due to an unplanned change of aircraft model? I'm certain there might be other answers and that reasons may vary from occasion to occasion and different airlines, but please enlighten me here!&lt;/p&gt;&#xA;" OwnerUserId="1344" LastActivityDate="2015-08-02T20:48:33.390" Title="How do commercial flights get overbooked?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ClosedDate="2015-08-02T22:14:42.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="17508" PostTypeId="2" ParentId="17507" CreationDate="2015-08-02T20:48:33.390" Score="8" Body="&lt;p&gt;Airlines have lots of historical data for any given flight segment that they can use to give statistical probabilities of people missing flights due to various factors such as misconnection or just not showing up.  An airline is a profit driven corporation and to maximize revenue they want full airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they know for a flight that 5% +/- 2% of passengers fail to board they can pretty safely sell around 103% of the seats to maximize passengers and minimize risk of overboarding.  Statistics are averages, however, and if you sell 103% of your capacity it is entirely possible for a given instance of that flight to be overbooked.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases of overbooking, volunteers can be found that will give up seats if the plane becomes full.  US airlines generally top out at around $800 compensation for volunteers, so if you are willing to do so it can be advantageous to wait for them to get desperate for volunteers.  If no volunteers can be found it is possible to be involuntarily bumped off the flight and you should consult with the specific airline for any rights you may have in that case.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-08-02T20:48:33.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17509" PostTypeId="1" CreationDate="2015-08-02T22:10:01.257" Score="4" ViewCount="429" Body="&lt;p&gt;My Transponder Mode C (Altitude Reporting) function quit working.  The position reporting function is working fine.  I believe the failed component is the self contained Model A-30 Altitude Digitizer &quot;box&quot; that is bolted to the interior of the fire wall.  It has a connector cable to the transponder and a rubber pitot tube connection.  I am an Aerospace engineer with 32 years experience designing and testing Space Shuttle Main Engines and components.  I have done my own annuals and had my local FBO mechanic inspect the work and sign it off.  The replacement of the Altitude Digitizer box does not require the removal of the transponder - just bolt on the new box and re-connect the air tube and plug in the &quot;D&quot; connector to the transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft owner would that be approved for me to do as a non-complex assembly/maintenance?  I know the calibration would have to be done by my certified avionics shop personnel, but can I do the R &amp;amp; R of the box?  Having my avionics shop do it adds another \$200.00 to the calibration cost of $175.&lt;/p&gt;&#xA;" OwnerUserId="9650" LastEditorUserId="998" LastEditDate="2015-08-03T06:48:37.673" LastActivityDate="2015-08-03T06:48:37.673" Title="Am I allowed to replace my own Model A-30 Altitude Digitizer?" Tags="&lt;aircraft-maintenance&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17510" PostTypeId="2" ParentId="17504" CreationDate="2015-08-02T22:43:57.460" Score="39" Body="&lt;p&gt;Don't look at the fuel consumption of the airline flight in isolation. An airline would need to combine the fuel used by both the revenue-earning flight and the tanker, and then add the cost of operating it, too. Even if this could be shared by four or five revenue-earning flights, the total would still be worse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To find out how big the fuel saving by in-air refueling is, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8652/how-can-i-calculate-the-fuel-consumption-of-an-airbus-320-200-at-various-loads/8654#8654&quot;&gt;Breguet equation&lt;/a&gt; is your friend. Let's assume an L/D of 18, a thrust-specific fuel consumption of $b_f$ = 0.018 kg/kNs and a speed of Mach 0.82, which equates to &lt;a href=&quot;http://www.wolframalpha.com/input/?i=Mach%200.82%20at%2011.000%20m%20altitude&quot; rel=&quot;noreferrer&quot;&gt;$v$ = 279 m/s in 11.000 m altitude&lt;/a&gt;. Now look at the mass fractions which go with ranges of 8000 km and 2$\cdot$4000 km:&#xA;$$\frac{m_1}{m_2} = e^{\frac{R\cdot g\cdot b_f}{v\cdot L/D}}$$&#xA;Flying the distance in one go needs the plane to start with a fuel load equivalent to 32.5% of the landing mass, while an air-refueled flight needs only 2$\cdot$15.1%. The saving (fuel equivalent to 2.3% of airliner's landing mass) is real, but even if four others could benefit from the same tanker flight, it would need to cost less than the equivalent of the fuel price of 5$\cdot$2.3% = 11.5% of the airliner's landing mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the tanker needs to carry 5$\cdot$15.1% = 75.5% of the airliner's landing mass in fuel, it needs to be an airliner-sized aircraft itself. Add more if the tanker needs to do even as much as to take off, let alone fly to a refueling point and wait there. And the fuel saving needs not only to pay for the tanker's fuel needs, but also for its crew, maintenance and depreciation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_refueling&quot; rel=&quot;noreferrer&quot;&gt;Aerial refueling&lt;/a&gt; is a great technology &lt;a href=&quot;https://aviation.stackexchange.com/questions/12671/why-is-mid-air-refueling-worth-it-or-is-it-at-all/12675#12675&quot;&gt;to make complex military scenarios possible&lt;/a&gt;, but is a very ressources-hungry beast.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-02T22:43:57.460" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17511" PostTypeId="2" ParentId="17509" CreationDate="2015-08-02T22:49:16.460" Score="8" Body="&lt;p&gt;Per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=fe914f2c1217fa1c19e2b6c42b804018&amp;amp;mc=true&amp;amp;node=se14.1.43_13&amp;amp;rgn=div8&quot;&gt;14 CFR 43.3(d)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A person working under the supervision of a holder of a mechanic&#xA;  or repairman certificate may perform the maintenance, preventive&#xA;  maintenance, and alterations that his supervisor is authorized to&#xA;  perform, if the supervisor personally observes the work being done to&#xA;  the extent necessary to ensure that it is being done properly and if&#xA;  the supervisor is readily available, in person, for consultation.&#xA;  However, this paragraph does not authorize the performance of any&#xA;  inspection required by Part 91 or Part 125 of this chapter or any&#xA;  inspection performed after a major repair or alteration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means if you are not a mechanic yourself, you can still perform this work as long as it is supervised by someone who is authorized to perform the work. Based on your question, I assume that you actually want to perform this work yourself.  Further down in 14 CFR 43.3(g), the FARs state the type of work you can perform without supervision:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Except for holders of a sport pilot certificate, the holder of a pilot&#xA;  certificate issued under part 61 may perform preventive maintenance on&#xA;  any aircraft owned or operated by that pilot which is not used under&#xA;  part 121, 129, or 135 of this chapter. The holder of a sport pilot&#xA;  certificate may perform preventive maintenance on an aircraft owned or&#xA;  operated by that pilot and issued a special airworthiness certificate&#xA;  in the light-sport category.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Preventive maintenance is defined in  &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=fe914f2c1217fa1c19e2b6c42b804018&amp;amp;mc=true&amp;amp;node=ap14.1.43_117.a&amp;amp;rgn=div9&quot;&gt;Appendix A to 14 CFR 43&lt;/a&gt;, paragraph C. If a function does not appear in this list, it is not preventive maintenance, and as such must be performed by personnel authorized to perform repair work. The only item in this list that is even remotely relevant to your situation is item 31:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Removing and replacing self-contained, front instrument panel-mounted&#xA;  navigation and communication devices that employ tray-mounted&#xA;  connectors that connect the unit when the unit is installed into the&#xA;  instrument panel, (excluding automatic flight control systems,&#xA;  transponders, and microwave frequency distance measuring equipment&#xA;  (DME)). The approved unit must be designed to be readily and&#xA;  repeatedly removed and replaced, and pertinent instructions must be&#xA;  provided. Prior to the unit's intended use, and operational check must&#xA;  be performed in accordance with the applicable sections of part 91 of&#xA;  this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that your situation does not appear to qualify, because the item you are replacing is not part of a self-contained, tray-mounted device.  Even if it were, you would still not be authorized to perform the work because this item &lt;em&gt;specifically excludes&lt;/em&gt; work on transponders. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, I am not an attorney nor do I perform aircraft repairs, so my interpretation is completely non-qualified. For the best answer, I would suggest contacting your local &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot;&gt;Flight Standards District Office&lt;/a&gt; for guidance.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-08-02T22:49:16.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17512" PostTypeId="1" AcceptedAnswerId="17514" CreationDate="2015-08-02T22:49:54.287" Score="1" ViewCount="1278" Body="&lt;p&gt;Unless otherwise specified, in what direction and what duration of leg should be flown if assigned a hold?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-02T23:18:52.970" Title="How is a standard holding pattern flown?" Tags="&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17513" PostTypeId="1" AcceptedAnswerId="17519" CreationDate="2015-08-02T23:09:09.593" Score="2" ViewCount="136" Body="&lt;p&gt;I'm looking for the current release of the FAA's Instrument Procedures Handbook. The &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;nofollow&quot;&gt;FAA website for the IPH&lt;/a&gt; shows FAA-H-8083-16, but other FAA documentation I've found references FAA-H-8261-1A. I've looked for places to buy the Instrument Procedures Handbook such as Amazon and found that they're offering FAA-H-8261-1A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which one is current?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For future reference, how do I found the most recent release of an FAA publication?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-03T02:50:39.463" Title="Which version of the FAA's Instrument Procedures Handbook is current?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17514" PostTypeId="2" ParentId="17512" CreationDate="2015-08-02T23:14:42.780" Score="4" Body="&lt;p&gt;Holding procedures are defined by each country for their own airspace. With that said, member countries of the International Civil Avation Organization (ICAO) generally follow the guidance of Part I, Section 6, Chapter 1 in &lt;a href=&quot;http://dcaa.trafikstyrelsen.dk:8000/icaodocs/Doc%208168%20-%20Aircraft%20Operations/Volume%201%20Flight%20Procedures,%205th%20ed..pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO Doc 8168&lt;/a&gt;, Aircraft Operations, Volume I, Flight Procedures:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Section 1.1.3 - The procedures described in this chapter are related&#xA;  to right turn holding patterns. For left turn holding patterns, the&#xA;  corresponding entry and holding procedures are symmetrical with&#xA;  respect to the inbound holding track.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the document does not explicitly state that right-hand holding patterns are the default, it is implied.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Section 1.4.9 - The still air time for flying the outbound entry&#xA;  heading should not exceed: a) one minute if at or below 4 250 m (14&#xA;  000 ft); or b) one and one-half minutes if above 4 250 m (14 000 ft).&#xA;  Where DME is available, the length of the outbound leg may be&#xA;  specified in terms of distance instead of time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Member countries can deviate from these standards, but if they do, they are supposed to notify ICAO and publish these differences in their respective Aeronautical Information Publication.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-08-02T23:14:42.780" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17516" PostTypeId="1" CreationDate="2015-08-02T23:31:34.707" Score="7" ViewCount="3609" Body="&lt;p&gt;I would like to know if, in addition to any MEL requirements, there is any regulation or requirement about having an operational TCAS II while operating in US airspace?&lt;/p&gt;&#xA;" OwnerUserId="9647" LastEditorUserId="62" LastEditDate="2015-08-03T01:23:14.150" LastActivityDate="2019-05-02T22:07:37.170" Title="Is TCAS II required in the US?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17518" PostTypeId="2" ParentId="17516" CreationDate="2015-08-03T02:08:29.243" Score="-2" Body="&lt;p&gt;No.  It's not required in the United States.  There is nothing in Part 25 of the regulations.  However, if you install one it should comply with this AC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;www.faa.gov/documentLibrary/media/Advisory_Circular/20-151B.pdf&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-08-03T02:08:29.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17519" PostTypeId="2" ParentId="17513" CreationDate="2015-08-03T02:50:39.463" Score="2" Body="&lt;p&gt;8083-16 ,dated 2014, is current version, superseded 8261-1A. It is stated in &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Summary_of_Changes.pdf&quot; rel=&quot;nofollow&quot;&gt;Summary of Change&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For future reference, the FAA page you linked in the question is best resource available.&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-08-03T02:50:39.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17520" PostTypeId="2" ParentId="17516" CreationDate="2015-08-03T03:41:24.953" Score="3" Body="&lt;p&gt;TCAS II is required for most airline flights. This is not a requirement for certification, and the TCAS may or may not be on the MEL. However, most flights under part 121 (scheduled airline service, as well as some freight) require TCAS II.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1ba894a9fff26716db7d7ef0733c7e8e&amp;amp;mc=true&amp;amp;node=se14.3.121_1356&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;FAR 121.356&lt;/a&gt;, &quot;Turbine-powered airplane of more than 33,000 pounds maximum certificated takeoff weight&quot; must be operated with equipment that meets a list of standards, but is essentially equivalent to just requiring TCAS II. Smaller aircraft with 10-30 seats can use TCAS-I.&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2015-08-03T03:41:24.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17523" PostTypeId="2" ParentId="14770" CreationDate="2015-08-03T07:13:45.913" Score="2" Body="&lt;p&gt;The FC I used to belong to had it's own fuel trailer (custom-built with dual double-walled, insulated cryogenic 100-gallon tanks, a manually-operated fuel pump, a totalizer, a delivery hose and nozzle, and appropriate grounding cables.  Excluding the cost of the basic flat-bed trailer itself (one of the FC members loaned it to the club) we had less than $1500 invested in the outfit - including inspection and trailer licensing fees.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering we would be carrying 200 gallons of MOGAS on public highways we had to be VERY careful as to WHEN we were ON the highways (basically very late at night, and we drove on lightly-used roads/streets) - and we had to have insurance commensurate with the commodity we were carrying.  We used this trailer for several years - without any incident(s) - but, in the end, we all felt un-easy about doing so and eventually we abandoned the idea and reverted to using hand-carried gas cans.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FC disbanded years ago and I don't know what ever happened to the fuel rig - I believe it went back to the FC member who built it in the first place (his materials costs and his labor bought him a club membership, whereas the rest of us had to ante up actual cash to help buy the airplane the FC bought.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ahhh, the good ol' days....&lt;/p&gt;&#xA;" OwnerUserId="9606" LastActivityDate="2015-08-03T07:13:45.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17525" PostTypeId="2" ParentId="17480" CreationDate="2015-08-03T08:01:55.277" Score="7" Body="&lt;p&gt;Yes, it's usually done by &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_P-3_Orion#Engine_loiter_shutdown&quot; rel=&quot;nofollow noreferrer&quot;&gt;P-3 Orion&lt;/a&gt;. While it's usual on the P-3 to shut down engine 1, sometimes engine 4 is shut down, but engine 4 drives a generator, thus the load on the remaining generators increases. Also, the minimum altitude to maintain in flight ASL/AGL increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod#Overview&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nimrod's crew did the same thing&lt;/a&gt; while on patrol. However, we're talking about ASW aircraft, designed for very long patrol/loiter periods while on station.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="17732" LastEditDate="2017-05-24T19:32:58.300" LastActivityDate="2017-05-24T19:32:58.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17526" PostTypeId="2" ParentId="17504" CreationDate="2015-08-03T10:18:45.140" Score="6" Body="&lt;p&gt;&lt;strong&gt;2019 update: site is dead (now a scam service)&lt;/strong&gt;. See wayback machine &lt;a href=&quot;https://web.archive.org/web/20160503183747/http://www.cruiser-feeder.eu/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The people from Cruiser-Feeder &lt;a href=&quot;http://www.cruiser-feeder.eu/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.cruiser-feeder.eu/&lt;/a&gt; try to make it happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is part of the abstract from a &lt;a href=&quot;http://www.cruiser-feeder.eu/downloads/van-birgelen---air-to-air-refuelling-of-civil-.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;paper&lt;/a&gt; describing their approach:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this paper it will be described how the safety of air-to-air refuelling has been assessed, and how&#xA;  proposed new or amended regulations and acceptable means of compliance have been defined&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They even created a conceptual design of joint-wing tanker for civil operations: &lt;a href=&quot;http://www.cruiser-feeder.eu/downloads/li-la-rocca---conceptual-design-of-a-joint-win.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.cruiser-feeder.eu/downloads/li-la-rocca---conceptual-design-of-a-joint-win.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In their papers, you will find data for which flights mid air refuelling is worth it, how they want to make it happen, and some interesting facts.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="4105" LastEditDate="2019-12-24T06:46:53.473" LastActivityDate="2019-12-24T06:46:53.473" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="17527" PostTypeId="1" AcceptedAnswerId="17529" CreationDate="2015-08-03T12:48:59.317" Score="10" ViewCount="4562" Body="&lt;p&gt;After watching many documentaries about air plane crashes, it seems that aviation industry learned many of its lessons from disasters. For example, from the 2 mid-air explosion of &lt;strong&gt;de Havilland DH 106 Comet&lt;/strong&gt; in 1950s they learned a lot about metal fatigue that can cause Explosive decompression. So, I'm curious to know how did the industry come to know about the drastic difference in air pressure that occurs in high altitude? Was the knowledge already there before an airplane was even invented?&lt;/p&gt;&#xA;" OwnerUserId="9659" LastEditorUserId="9659" LastEditDate="2015-08-04T00:51:55.497" LastActivityDate="2015-08-04T00:51:55.497" Title="How did aviation industry come to know about the drastic difference in air pressure in high altitude?" Tags="&lt;airliner&gt;&lt;high-altitude&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17528" PostTypeId="1" CreationDate="2015-08-03T12:53:23.653" Score="2" ViewCount="7980" Body="&lt;p&gt;What are the regulations regarding crop dusting and flying low over private property. Do they have to file a flight plan and is there a way to make your private property a no fly zone?&lt;/p&gt;&#xA;" OwnerUserId="9660" LastEditorUserId="595" LastEditDate="2015-08-03T13:05:46.463" LastActivityDate="2015-08-03T22:21:06.593" Title="Crop dusting regulations in the US" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-03T23:05:56.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="17529" PostTypeId="2" ParentId="17527" CreationDate="2015-08-03T12:57:19.483" Score="41" Body="&lt;p&gt;The entire reason why the Comet broke up in midair is because they pressurized the plane in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was known for a long time that air at high altitude was thinner. This can be experimentally verified by taking a barometer up to a mountain. &lt;a href=&quot;https://en.wikipedia.org/wiki/Barometer#History&quot;&gt;This was first done in 1648&lt;/a&gt; (and subject to hot debate regarding the nature of air) more than 250 years before the Wright brothers first flew.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-08-03T13:27:54.323" LastActivityDate="2015-08-03T13:27:54.323" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17530" PostTypeId="2" ParentId="17495" CreationDate="2015-08-03T13:28:35.373" Score="7" Body="&lt;p&gt;The simplest thing is to ask someone local where runups are usually done: the FBO, Ground Control or another pilot. If you can't find out then you can do them anywhere you like as long as it's safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports have specific runup areas but they aren't always obvious. For example, KPDK has runup areas at both ends of taxiway A, they're shown on the &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/diagrams/&quot; rel=&quot;noreferrer&quot;&gt;airport diagram&lt;/a&gt; as 'bulges' in the taxiway but they aren't labelled. You &lt;em&gt;might&lt;/em&gt; notice them when you land and taxi but you might not. I've circled one of the runup areas in red here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WnrcWm.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WnrcWm.png&quot; alt=&quot;KPDK runup area&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there are no runup areas, the 'default' location is the one you remember from training: on the taxiway just before reaching the runway, angled into the wind. If the taxiway is wide enough, you can move to the edge so that other aircraft can pass you if they're ready before you. That's very common and it's what many pilots will expect you to do, even if you have to block the taxiway for a couple of minutes. This is where you have to use some judgement: if you know that you need to take your time on runups - perhaps it's an unfamiliar aircraft, or you've just had maintenance done and you're double-checking everything - then you might look for another spot where you won't be in the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blocking other aircraft from reaching the runway is always a possibility, but at airports with a lot of GA traffic - and especially a lot of flight training - it's common and just something to be expected. That doesn't mean you should take forever doing your checks and of course some other pilots will always get annoyed at even minor delays, but if the only safe place to do runups is the taxiway then just do them there and the others will wait.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option is to do runups on the ramp or before entering the &lt;a href=&quot;https://en.wikipedia.org/wiki/Maneuvering_area&quot; rel=&quot;noreferrer&quot;&gt;movement area&lt;/a&gt; so that you don't block other aircraft anywhere. That's especially important at airports with scheduled commercial flights because they usually have very precise departure times and getting stuck behind another aircraft for even a few minutes could be an issue. If you're in that environment, then you should definitely check with Ground Control what they want you to do. But be careful about doing runups on the ramp because of people and vehicles moving around. Also be wary about doing runups a long way from the runway: during a long taxi you might change something (e.g. the mixture or fuel controls) and then forget to reset it for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one place you should &lt;em&gt;never&lt;/em&gt; do runups is on the runway itself. Sitting there for several minutes blocking the runway for landing traffic and unable to see final approach behind you isn't a good position to put yourself in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, avoiding blowing debris into other aircraft should be simple: just look around you, and don't position the aircraft so that your prop blast is going somewhere it shouldn't.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-09-19T17:34:12.900" LastActivityDate="2017-09-19T17:34:12.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17534" PostTypeId="2" ParentId="17527" CreationDate="2015-08-03T14:13:34.033" Score="22" Body="&lt;p&gt;Aside from mountaineering investigations, the service ceiling of WWII propeller-driven aircraft like the Spitfire was pushed up from about 34,000 feet to 45,000 feet, so the general effect of reduced air pressure on aircraft and engine performance was already known. Of course both civil and military aircraft were unpressurised before the start of jet-powered civil aviation (though there were some experiments with full-body pressurised suits, to avoid damaging the aircrew more than the plane at those altitudes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the significant novelty was discovering the effect of cyclic stresses (a.k.a. &quot;fatigue&quot;) in a new situation, namely of the order of 100 to 1000 loading cycles to failure. Before that, the most common design consideration was one loading cycle, where over-stressing caused immediate failure. With a suitably large safety factor and fortuitous choice of materials, that design criterion would also give an &quot;infinite life&quot; for high-cycle fatigue situations like rotating machinery (e.g. piston engines). New materials, plus lower safety factors driven by the need for minimum weight, discovered a new &quot;cliff edge&quot; for designers to &quot;fall off&quot; - and the history of engineering contains many examples of cliff edges being discovered by falling off them.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-08-03T14:13:34.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17535" PostTypeId="1" CreationDate="2015-08-03T14:44:17.450" Score="5" ViewCount="1935" Body="&lt;p&gt;Boeing 747 nose&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NHxuy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NHxuy.jpg&quot; alt=&quot;Boeing 747 head&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which looks like a goose head&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/D668p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D668p.jpg&quot; alt=&quot;Goose head&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which, for me, much uglier than 737&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kTir1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kTir1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which has a head similar to&lt;a href=&quot;https://i.stack.imgur.com/5E58V.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5E58V.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which is of course, much better looking from my point of view. Why are there different designs of the nose for planes by the same manufacturers? What effects do the different designs have?&lt;/p&gt;&#xA;" OwnerUserId="9659" LastEditorUserId="9659" LastEditDate="2015-08-03T19:11:47.080" LastActivityDate="2015-10-03T20:01:23.033" Title="How much effect does the nose design of the plane have?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="17537" PostTypeId="2" ParentId="17503" CreationDate="2015-08-03T16:27:45.450" Score="8" Body="&lt;p&gt;There is a standard called &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot;&gt;ETOPS&lt;/a&gt; for two-engines aircraft on which they are certified. It specifies the maximum distance an aircraft can be away from the nearest airport while it flies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the A330, ETOPS is &lt;strong&gt;&lt;a href=&quot;http://www.prnewswire.com/news-releases/boeing-747-8-intercontinental-receives-faa-approval-for-330-minute-etops-300052074.html&quot;&gt;180 minutes / 1,700 nm / 3148 km&lt;/a&gt;&lt;/strong&gt;. It may sounds like a lot of flying in case of an emergency but the aircraft is designed with enough redundancy (2 engines / parallel and backup avionics system).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard is more important in case of a two-engines aircraft where losing one engine has more impact than on a four-engines aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9662" LastEditorUserId="65" LastEditDate="2015-08-03T16:41:36.607" LastActivityDate="2015-08-03T16:41:36.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17538" PostTypeId="2" ParentId="17495" CreationDate="2015-08-03T16:45:43.393" Score="1" Body="&lt;p&gt;The shortest, simplest (but probably least helpful) answer is that it depends on the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At DFW there's a fairly large holding area on each side of the 17L-35R GA runway, with space to turn before reaching the hold short line. Departing aircraft can do a quick runup at the line while waiting for clearance to enter, provided the following aircraft has some idea of what's about to happen and isn't tailgating. If the pilot misses this opportunity because a following aircraft got too close, he can still do a full runup on the numbers prior to releasing wheel brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fetWm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fetWm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the smaller Addison Airport, there's only one main taxiway that's fairly narrow and close in, so they built a special &quot;cul-de-sac&quot; specifically for runup tests. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZheOG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZheOG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual procedure is to taxi to face south to do your runup just shy of the stop line, pretty much where the plane in this image is. They might have originally intended small planes to face west, but that's dangerous for jets to try as there's road traffic fairly close in just the other side of a fence, so now they just say face south whether you're in an LSA or a 737. Other aircraft are supposed to hold short of the stop line to the right, but if you have several small craft in sequence it's fairly safe to have a second or even a third aircraft in here. If someone gets too close behind you in here - lots of student pilots fly out of here so you have to be ready for anything - you can do your runup on the displaced threshold. Of course you can only enter this area with takeoff clearance (or at least a taxi and hold), so if you find a problem here it's slightly more inconvenient, but you can still quickly duck out of the sequence using the runway exit in the picture.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-03T17:10:14.453" LastActivityDate="2015-08-03T17:10:14.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17539" PostTypeId="1" CreationDate="2015-08-03T17:07:18.667" Score="5" ViewCount="1102" Body="&lt;p&gt;Could any large airliner or GA aircraft survive a horizontal roll? Or would a large aircraft break up from structural damage?&lt;/p&gt;&#xA;" OwnerUserId="9494" LastActivityDate="2015-08-03T18:24:54.447" Title="Would a large airliner such as a 747 or an A380 survive an inversion?" Tags="&lt;airliner&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ClosedDate="2015-08-03T19:34:21.880" ContentLicense="CC BY-SA 3.0" />
  <row Id="17540" PostTypeId="2" ParentId="17498" CreationDate="2015-08-03T17:14:45.363" Score="3" Body="&lt;p&gt;The maneuver as described is not a particularly efficient way of losing altitude: You're alternately stalling &amp;amp; recovering from the stall.&lt;br&gt;&#xA;More efficient descent procedures exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The technique of holding the aircraft in a wings-level stall (or putting it into a spin) was used in the early days of aviation to get back below a cloud deck if you were trapped &quot;on top&quot;: when you broke out below the clouds you would recover from the maneuver &amp;amp; proceed to your destination / landing (if you were lucky enough to have sufficient altitude to recover when you came out of the bottom of the clouds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Needless to say neither of these maneuvers makes much sense for an unmanned aircraft: If your goal is a rapid descent you will execute a maneuver that gives you the best possible descent rate (such as the emergency descent procedure in the POH, or the one in the Airplane Flying Handbook); If your goal is to get back below the clouds you've already busted the regs (you need to maintain visual line-of-sight with your UAS), but if and when the regulations change you should also be able to recover using more modern techniques (like descending on an instrument approach or using a synthetic vision system) to ensure you don't hit anything, like another aircraft. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-03T17:14:45.363" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17541" PostTypeId="2" ParentId="17539" CreationDate="2015-08-03T17:24:35.523" Score="10" Body="&lt;p&gt;Could it? Yes.&lt;br&gt;&#xA;&lt;a href=&quot;http://youtu.be/Ra_khhzuFlE&quot;&gt;Tex Johnson famously performed a roll in a Boeing 707.&lt;/a&gt; If performed properly it is a 1G maneuver (the airframe experiences +1G stresses through the maneuver - as far as it's concerned nothing unusual is happening).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should you attempt such a maneuver without aerobatic training? &lt;strong&gt;No.&lt;/strong&gt;&lt;br&gt;&#xA;Should you attempt it in an aircraft not certificated for aerobatic flight? &lt;strong&gt;Absolutely Not.&lt;/strong&gt;&lt;br&gt;&#xA;This is one of those &quot;If you do it wrong the wings fall off&quot; maneuvers, and chances are you're not Tex Johnson.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-03T17:24:35.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17542" PostTypeId="2" ParentId="17539" CreationDate="2015-08-03T17:54:59.050" Score="6" Body="&lt;p&gt;A properly executed roll isn't an inversion as far as the airplane is concerned.  A ground observer will see the airplane roll and be upside down for a time, but the airplane in a 1G roll will think it is right side up the entire time.  An observer in the airplanes reference frame would not experience the roll as the gravity vector is a constant 1G pointed through the bottom of the seat during the entire roll (see &lt;a href=&quot;https://www.youtube.com/watch?v=pMWxuKcD6vE&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As pointed out in &lt;a href=&quot;https://aviation.stackexchange.com/a/17541/65&quot;&gt;this other answer&lt;/a&gt;, don't do this in an airplane not certified for it.  Yes, it can be done, but if not flown perfectly the outcome is likely death in a large turbojet airplane.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-03T18:24:54.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17543" PostTypeId="2" ParentId="17527" CreationDate="2015-08-03T18:48:33.520" Score="6" Body="&lt;p&gt;The range of air pressure from sea level to the maximum ceiling of modern aircraft was known even before the airplane was invented. The difference between the troposphere and stratosphere was discovered by balloon measurements by Teisserenc de Bort in 1902. Most passenger airlines fly in lower levels of the stratosphere. No planes can fly above the stratosphere.&lt;/p&gt;&#xA;" OwnerUserId="1415" LastActivityDate="2015-08-03T18:48:33.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17544" PostTypeId="2" ParentId="17503" CreationDate="2015-08-03T18:58:27.557" Score="12" Body="&lt;p&gt;Although it appears that going from Australia to North America, there is nothing but the great Pacific Ocean underneath. However the truth is (as &lt;a href=&quot;https://aviation.stackexchange.com/questions/17503/what-options-would-qantas-flights-7-8-have-in-case-it-hits-some-emergency#comment41168_17503&quot;&gt;Federico mentioned&lt;/a&gt;) that there are many airports along the way which can allow an A380 to land there, and many more close enough that an A380 can divert to in case of an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the early days of this flight (Qantas 8 to be exact), it had to &lt;a href=&quot;http://www.traveller.com.au/too-far-qantas-747-forced-to-land-for-more-fuel-on-dallas-route-1fdl1&quot; rel=&quot;nofollow noreferrer&quot;&gt;stop at Noumea, New Caledonia&lt;/a&gt; for a fuel stop as the pilots thought that it would be safer to do that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia has a list of &lt;a href=&quot;https://en.wikipedia.org/wiki/Diversion_airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;diversion airports in Pacific&lt;/a&gt;. If you turn on the options to view nearby airports on &lt;a href=&quot;https://flightaware.com/live/flight/QFA7&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightAware&lt;/a&gt; and zoom in on the map, you can find many airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be noted that not &lt;strong&gt;all&lt;/strong&gt; emergencies require an &lt;a href=&quot;https://en.wikipedia.org/wiki/Emergency_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;immediate landing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-03T18:58:27.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17545" PostTypeId="2" ParentId="17528" CreationDate="2015-08-03T19:28:20.493" Score="0" Body="&lt;p&gt;To answer your questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A crop duster does not have to file a (normal) flight plan. They do have to file a special &quot;operations&quot; plan if they are going to be spraying chemicals. Notice of the intended operation must be given to the public by some effective means, such as daily newspapers, radio, television, or door-to-door notice. A plan for [the spraying] operation must be submitted to, and approved by appropriate personnel of the FAA Flight Standards District Office having jurisdiction over the area where the operation is to be conducted. The plan must include consideration of obstructions to flight; the emergency landing capabilities of the aircraft to be used; and any necessary coordination with air traffic control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircraft must maintain a height of at least 500 feet above ground or objects on the ground, like a house. (Minimum Safe Altitude) A crop duster can go below this height only to operate to apply chemicals and for no other reason. The exact text of the exception reads as follows: &quot;No person may operate an aircraft over a congested area below the altitudes prescribed in part 91 of this chapter except during the actual dispensing operation, including the approaches and departures necessary for that operation.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You cannot prevent someone from flying over your house.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone is flying over your house at less than 500 feet, you can file a complaint with the FAA by calling (703) 230-7664. Please observe the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Identification - Can you identify the aircraft? Did you record the registration number which appears on the fuselage or tail? (On U.S. registered aircraft, that number will be preceded with a capital &quot;N&quot;.)&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Time and Place - Exactly when did the incident(s) occur? Where did this happen? What direction was the aircraft flying?&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Altitude - How high (low) was the aircraft flying? On what do you base your estimate? Was the aircraft level with or below the elevation of a prominent object such as a tower or building? Did you obtain photographs? Are there any witnesses who could confirm your estimate - do you have their names, addresses, telephone numbers?&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Supporting Evidence&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Witnesses, Police&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• Photographs&lt;BR&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-08-03T22:21:06.593" LastActivityDate="2015-08-03T22:21:06.593" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17546" PostTypeId="2" ParentId="198" CreationDate="2015-08-03T19:49:08.923" Score="0" Body="&lt;p&gt;Flying in a small aircraft is far more dangerous than other methods of transportation (see statistics in other answers). I would not recommend it unless you have a positive reason to use a small plane. Thrill seeking or taking aircraft flights for &quot;fun&quot; is not a good idea from a statistical point of view. I fly strictly for practical reasons and I would recommend that as a general policy for anyone considering flying either as a pilot or a passenger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying in a small aircraft is not as dangerous as base jumping or scuba diving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot nature, skill and attitude have a large impact on the danger in a flight. Most people get killed in small planes because the pilot did something that was either foolish (like taking shortcuts in the pattern), reckless (flying into storms) or because they panicked. If a pilot acts cocky, that is a huge warning sign.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="110" LastEditDate="2015-08-03T20:25:48.363" LastActivityDate="2015-08-03T20:25:48.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17547" PostTypeId="2" ParentId="17492" CreationDate="2015-08-03T19:49:42.850" Score="1" Body="&lt;p&gt;Probably the best thing to do is to start looking for your reference as you start to lose the runway under your nose. Hopefully at that point you'll be low enough to identify something that will stand out from the crowd all the way down to the ground. You may also favor choosing something closer in from the horizon at 2000AGL, to ensure you don't lose it behind the horizon as you descend. For me, flying out of Addison, it's pretty easy; the runway faces downtown Addison about 3 miles south-southeast (a row of corporate headquarters buildings along the Dallas North Tollway) which is far enough out to line up on but close enough and tall enough you'll see it right up until you pass the numbers. Flying into a more rural strip, you might have more trouble identifying a good reference that you can keep in sight as you descend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some potential issues with this general strategy:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Your reference point will lie well beyond the runway by design. Don't fixate on it; that will cause you to subconsciously stay higher than your intended glide path as you fly toward your reference, potentially overshooting the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Your reference is a single point. That point and your aircraft make a line, which you want to be colinear with the runway. But, your aircraft is a moving point, so it's not necessarily true that you'll be in line with the runway even if your nose is on the reference point. Instead of one reference point, I'd pick two (even if they're not perfectly in line) and focus on keeping both reference points steady relative to each other.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you can't see the runway, you may not be able to see surrounding visual aids like the glide slope indicators, which are just as important as staying lined up. Addison's PAPI lights are off to the right when approaching runway 15, which is stupid as my instructor can see them perfectly while I'm blind unless I nose down every few seconds to keep track (not an option without flaps).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While I wouldn't rely on it completely in VMC, if you have a VOR receiver aboard and the runway has an instrument approach, you can tune into the ILS frequency and use the &quot;cross&quot; alongside visual references to manage your approach during the time the runway is hidden from view. The ILS system is pretty well-standardized, while the visual references at each airport are not, so if you become accustomed to an ILS-augmented visual landing, the basic procedure can be applied to any airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reasons I wouldn't rely totally on it include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You're not instrument-rated (unless you are) so flying with your head in the gauges can easily kill you. Glance at it to ensure you're where you think you are, but rely on your visual references whenever you can.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You're not flying a pure instrument approach under IFR, so you still have to &quot;see and avoid&quot; even if you have tower staff spacing traffic around you (unless you ask for a &quot;pop-up&quot; instrument approach, effectively switching from VFR to IFR).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ILS availability/accuracy is not guaranteed in daytime VMC because the ILS critical areas are not required to be protected during these times. If you tell the tower what you're doing, they can advise ground traffic to use the ILS holds, but there may already be traffic in an ILS critical area and if so there's little the tower can do.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ILS may contradict visual indicators to varying degrees, because the ILS glideslope is projected from a different point along the runway than the PAPI/VASI array. You therefore shouldn't expect the ILS cross to be perfectly centered along the same path that gives you two white PAPI lights.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Radio-based ILS isn't available at every airstrip. In such cases you simply must fly a purely visual approach, and having relied on ILS to give you the proper glide slope instead of developing your sight picture will prove to be a crutch in such situations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-03T19:49:42.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17548" PostTypeId="1" AcceptedAnswerId="17551" CreationDate="2015-08-03T20:46:00.670" Score="1" ViewCount="2955" Body="&lt;p&gt;For example, what about the baggage compartment? Landing gear housing? Avionics?&lt;/p&gt;&#xA;" OwnerUserId="2560" LastEditorUserId="643" LastEditDate="2015-08-06T05:08:38.273" LastActivityDate="2015-08-06T05:08:38.273" Title="What areas of a commercial airliner are pressurized besides the cabin?" Tags="&lt;commercial-aviation&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17549" PostTypeId="2" ParentId="17474" CreationDate="2015-08-03T20:46:22.487" Score="1" Body="&lt;p&gt;Of the two possibilities you mentioned, the most likely is the height of the top of the vertical stabilizer from the ground with the plane parked normally. For conventionally-configured tricycle-gear airplanes, this point is the tallest on the aircraft, and therefore this height is useful in determining the required clearance for covered parking areas and hangar openings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few designs for which a different height measurement is needed. A tail-dragger's tallest point will usually be either the cockpit or a point in the prop's sweep (more likely the cockpit for civilian designs, more likely the prop for old warbirds). The Predator drone uses an inverted V-tail, and its tallest point is actually its communications antenna. The Beechcraft V35 Bonanza's tail tips are within a couple of inches of the top of the cabin. In all these cases a &quot;parked height&quot; figure is required which will be greater than that of the vertical stabilizer.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="9875" LastEditDate="2015-08-27T13:04:08.763" LastActivityDate="2015-08-27T13:04:08.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17550" PostTypeId="1" AcceptedAnswerId="17552" CreationDate="2015-08-03T20:57:37.850" Score="5" ViewCount="967" Body="&lt;p&gt;Pilot educational curriculum includes learning about magnetic compass errors intrinsic to their construction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A standard magnetic compass in an airplane erroneously shows turns when accelerating or decelerating on an east or west heading. They also read incorrectly during turns from the north or the south.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is about more advanced instruments like a fluxgate compass found slaved to an HSI or a magnetometer used in an AHRS. Are these systems impervious to the compass errors present in a magnetic compass?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2016-12-01T18:22:56.047" LastActivityDate="2016-12-01T18:22:56.047" Title="Are directional instruments like an HSI or AHRS immune to magnetic compass error?" Tags="&lt;navigation&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17551" PostTypeId="2" ParentId="17548" CreationDate="2015-08-03T20:58:16.687" Score="8" Body="&lt;p&gt;Baggage, yes, landing gear, no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage of an airliner is typically &quot;capped&quot; by two bulkheads, the forward and aft pressure bulkheads. These are roughly spherical sections that seal the central &quot;cylinder&quot; of the aircraft's fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a 787's forward bulkhead:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zS5Xq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zS5Xq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;... and a 767's aft pressure bulkhead:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VOcTu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VOcTu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practically all the space in the fuselage itself between these two bulkheads is pressurized during high-altitude flight. This includes the baggage compartment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gear assemblies, however, are typically not pressurized. For some jets like the 737, this is fairly obvious:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ePWOI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ePWOI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other designs with full doors for the gear assemblies aren't as obvious, but in general it's neither feasible nor desirable to pressurize the landing gear housings when airborne.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-03T20:58:16.687" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17552" PostTypeId="2" ParentId="17550" CreationDate="2015-08-03T21:20:54.047" Score="3" Body="&lt;p&gt;The short answer is yes, but for different reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The analog HSI in most aircraft that have them either has an internal directional gyroscope, or it is slaved to the directional gyro (more often the former than the latter as the HSI often replaces the DG). An analog DG/HSI must still be periodically corrected for precession error by levelling off, letting both instruments stabilize and then adjusting the HSI's card to the magnetic compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AHRS systems that power glass cockpits use a solid-state directional gyro that is corrected by a magnetometer (an antenna device that directly senses the relative direction of the magnetic field) rather than a floating magnet. This makes them impervious to the types of error commonly seen in floating compasses such as acceleration bias (which causes all the behaviors you mentioned). They can still be sensitive to nearby ferrous metal structural members and to electrical currents, requiring a digital version of &quot;spinning the compass&quot; with corrections input into the software that uses the magnetometer readings, and magnetic declination must also be accounted for (either mentally by the pilot, manually based on declination charts or in more sophisticated systems by directly incorporating position data from the GPS).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-03T22:20:35.810" LastActivityDate="2015-08-03T22:20:35.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17553" PostTypeId="2" ParentId="17535" CreationDate="2015-08-03T21:23:31.013" Score="1" Body="&lt;p&gt;Good question! The raised cockpit and the hump behind it make the 747 look like the goose. Raising the cockpit allows the hinged nose to come up to load freight. The raised area behind the cockpit was initially a lounge, and was then used for seating or cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://webcache.googleusercontent.com/search?q=cache:JQaEjjHjzKkJ:www.airspacemag.com/how-things-work/how-the-747-got-its-hump-4578877/&quot; rel=&quot;nofollow noreferrer&quot;&gt;How the 747 Got Its Hump, Smithsonian Air and Space &lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-8F:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CGCGK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CGCGK.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Photo by Olivier Cleynen&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="110" LastEditorUserId="5517" LastEditDate="2015-08-04T15:21:48.707" LastActivityDate="2015-08-04T15:21:48.707" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17554" PostTypeId="1" CreationDate="2015-08-03T23:15:05.787" Score="3" ViewCount="509" Body="&lt;p&gt;Is it possible to use the track instead of headings in the aim to apply a radar separation?&lt;/p&gt;&#xA;" OwnerUserId="9671" LastEditorUserId="19" LastEditDate="2016-07-08T09:52:27.423" LastActivityDate="2016-07-08T10:46:49.193" Title="Radar Control; is it possible for ATC to instruct track instead of heading?" Tags="&lt;radar&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17555" PostTypeId="2" ParentId="17554" CreationDate="2015-08-04T00:04:07.977" Score="8" Body="&lt;p&gt;Radar controllers take wind into consideration when issuing &lt;strong&gt;headings&lt;/strong&gt; - &quot;Fly heading one six zero&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Issuing a track would not be practical. This puts the burden of figuring out what course to fly on the pilot. Not all aircraft have a glass cockpit or instrumentation necessary to &lt;em&gt;easily, quickly, and accurately&lt;/em&gt; compute a heading to fly to stay on course. The radar controller knows real-time information, knows the 'big picture', and has practice issuing headings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual position is used to provide separation. Heading doesn't matter for separation.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-04T00:04:07.977" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17556" PostTypeId="1" CreationDate="2015-08-04T00:51:13.120" Score="3" ViewCount="516" Body="&lt;p&gt;In the early 70s, DC-10 planes had disastrous failures with cargo doors. It proved how massive a havoc faulty cargo doors can have on the planes. Despite those two incidents with Boeing 747 planes in the 80s prove that Boeing were not careful enough to avoid problem with the cargo doors. In fact, there is a striking similarity with what happened to DC planes in 1972(a warning) and in 1974(not learned from the warning) and what happened to Boeing 747 in 1985(warning) and in 1987(not learned from warning).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why didn't Boeing learn from what happened to DC-10 planes?&lt;/p&gt;&#xA;" OwnerUserId="9659" LastActivityDate="2015-08-04T07:48:19.097" Title="Despite the lessons from DC-10 planes in 70s, why didn't Boeing ensure their cargo doors didn't fail even until the end of the 80s?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-08-04T08:34:56.590" ContentLicense="CC BY-SA 3.0" />
  <row Id="17557" PostTypeId="1" CreationDate="2015-08-04T02:14:06.113" Score="8" ViewCount="5744" Body="&lt;p&gt;I have a private license for single engine land and I want to transition to helicopters. I have been told by some that learning helicopters is more of a challenge after learning fixed wing. However I have yet to see any good sources or explanation for this. Is this generally true and if so why?&lt;/p&gt;&#xA;" OwnerUserId="9400" LastActivityDate="2015-08-04T17:10:11.407" Title="Is it harder to learn to fly rotary wing after learning on fixed?" Tags="&lt;flight-training&gt;&lt;fixed-wing&gt;&lt;rotary-wing&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17558" PostTypeId="2" ParentId="12076" CreationDate="2015-08-04T05:42:12.077" Score="2" Body="&lt;p&gt;The &quot;jumbo jet&quot; moniker isn't exclusive to the 747, but is applied to any large commercial jet - the L-1011 and DC-10 (if I'm recalling the model names correctly) were also called &quot;jumbo jets&quot;, as is the large Airbus. It's just that the 747 was much more successful than its early competitors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other aircraft which are called &quot;jumbo jets&quot; &lt;a href=&quot;https://en.wikipedia.org/wiki/Wide-body_aircraft&quot; rel=&quot;nofollow&quot;&gt;are listed here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="6968" LastEditorUserId="6968" LastEditDate="2015-08-04T20:00:06.257" LastActivityDate="2015-08-04T20:00:06.257" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17559" PostTypeId="2" ParentId="17557" CreationDate="2015-08-04T07:43:49.763" Score="3" Body="&lt;p&gt;Rotary flying is much harder than fixed wing to learn, however learning after you get a fixed wing license is easier in some ways because you already know:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Radio procedures&lt;/li&gt;&#xA;&lt;li&gt;How to set up and use instruments&lt;/li&gt;&#xA;&lt;li&gt;Navigation and flight in controlled airspace&lt;/li&gt;&#xA;&lt;li&gt;Air law and regulations&lt;/li&gt;&#xA;&lt;li&gt;The &quot;gestalt&quot; of flying&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This means all you need to do is learn to fly the helicopter, which is tricky because helicopters are much less stable than fixed wing airplanes. If you take your hands off the controls of fixed wing airplane it will generally stay pointed where you put it, especially if it's trimmed properly. If you take your hands off of a helicopter's controls in hover things will go very, very badly in a real hurry so you have to be making constant control inputs. The controls of a helicopter are also very sensitive, it is a very different (and more challenging) type of flying. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-08-04T07:43:49.763" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17560" PostTypeId="2" ParentId="17556" CreationDate="2015-08-04T07:48:19.097" Score="9" Body="&lt;p&gt;Most probably because the failure modes were very different. In the DC-10 case the door could appear closed even though the locking mechanism was not properly engaged. On 747 that was not a problem; instead the electric motors opening the door had enough power to break the locking mechanism if electric power somehow made it around the switch that was part of the locking mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then, 2 years are not really enough to analyse a problem like this, develop a fix, test it and deploy it. The NTSB investigations alone often take longer than 2 years.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-04T07:48:19.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17561" PostTypeId="1" CreationDate="2015-08-04T10:22:12.760" Score="3" ViewCount="256" Body="&lt;p&gt;In La Réunion, people are currently searching for plane debris that could be from the MH370 crash and this morning &lt;a href=&quot;http://www.linfo.re/la-reunion/faits-divers/674376-enquete-mh370-un-debris-retrouve-sur-le-littoral-de-st-denis&quot; rel=&quot;nofollow noreferrer&quot;&gt;this object&lt;/a&gt; was found.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/OP8DQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OP8DQ.jpg&quot; alt=&quot;Image found at la Réunion&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone identify it?&lt;/p&gt;&#xA;" OwnerUserId="9675" LastEditorUserId="4197" LastEditDate="2015-08-04T12:20:17.993" LastActivityDate="2015-08-04T12:20:17.993" Title="Can anyone identify this object?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-08-04T12:47:20.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="17562" PostTypeId="2" ParentId="17561" CreationDate="2015-08-04T10:47:05.157" Score="3" Body="&lt;p&gt;We really shouldn't speculate, but it does not look like a panel piece for a door or window. Aside from two small warning lights on some models there shouldn't be very much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is very much speculation: Aside from the deep inset, which looks like it could have housed a CRT monitor, there are two holes for square aviation-style switches, and two holes, perhaps for backlighting, above it. The left hole looks very similar to an SD card slot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then again, it could have come from a boat or anything.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-08-04T10:47:05.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17563" PostTypeId="1" AcceptedAnswerId="17565" CreationDate="2015-08-04T11:07:08.493" Score="-1" ViewCount="288" Body="&lt;p&gt;The older  Cessna's (like 172,152) have an average wing span of about 10m, which would need about 2 lanes of some highway or some other road and would be easily available on some National Highway. The taxiing speed that Cessna can achieve is pretty decent. So, what problems would a person face trying to use a Cessna as a Car, one of them could be space, but what are some other problems, barring any regulatory/legal issues? Mainly I am demanding an answer from fuel, speed, and safety point of view.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-04T13:30:52.480" LastActivityDate="2015-08-04T13:30:52.480" Title="What difficulties would would a person face, trying to use a Cessna as a car?" Tags="&lt;cessna-172&gt;&lt;cessna-152&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ClosedDate="2015-08-04T13:32:30.520" ContentLicense="CC BY-SA 3.0" />
  <row Id="17564" PostTypeId="1" AcceptedAnswerId="17576" CreationDate="2015-08-04T11:19:07.423" Score="8" ViewCount="7537" Body="&lt;p&gt;I was wondering, how are Lufthansa able to unload luggage (&lt;a href=&quot;https://flightaware.com/live/flight/DLH760&quot; rel=&quot;noreferrer&quot;&gt;LH 760&lt;/a&gt;) of 500 passengers and load the luggage (&lt;a href=&quot;https://flightaware.com/live/flight/DLH761&quot; rel=&quot;noreferrer&quot;&gt;LH 761&lt;/a&gt;) of another 500 passengers, in just a 2 hour gap for return leg of 7000 KM FRA-DEL journey. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the average time taken to complete a typical loading and unloading operation for a fully loaded A380? Some simple maths in this case shows its about 14.4 seconds for unloading and loading, pretty very high.  But that's assuming that no time is spent in any  task other than handling luggage, which is pretty foolish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bonus Question&lt;/strong&gt; : How are the handlers able to complete this operation that fast? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-05T12:06:18.907" LastActivityDate="2020-02-21T16:41:22.333" Title="What is the average time taken to load and unload the luggage?" Tags="&lt;airbus-a380&gt;&lt;ground-operations&gt;&lt;baggage-handling-system&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17565" PostTypeId="2" ParentId="17563" CreationDate="2015-08-04T12:51:38.653" Score="2" Body="&lt;p&gt;Even assuming there is room - wings and the propellor could quite easily hit something or a pedestrian not looking where they were going... etc etc. An aeroplane is quite difficult to steer on the ground because the flight controls don't work very well if at all at low speeds - you use the steerable nosewheel which is connected to the rudder pedals and also the brakes (one on each rudder pedal that affect the main wheels). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the large areas of body and not least the wings and tail it would be affected by winds at street corners for example. It would have to keep its speed fairly low (10-20mph). Any faster and it would be very stressful for the pilot and quite easy to lose control of it. It would also be difficult to judge clearances from other objects at higher speeds. Cars don't have wings stuck out 15 feet either side of the driver!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that I am sure it is far easier to drive an aeroplane on the ground than it is a car in the air!&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-04T12:51:38.653" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17566" PostTypeId="2" ParentId="17441" CreationDate="2015-08-04T13:07:41.637" Score="2" Body="&lt;p&gt;While adding weight to an aeroplane increases fuel consumption because the wings have to work slightly harder and the nose has to be slightly higher which increases drag, and thus an higher power setting is required. So adding even one person is not fuel efficient compared to one less person. But the money received from that extra person will outweigh the additional fuel required.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-04T13:07:41.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17567" PostTypeId="2" ParentId="14971" CreationDate="2015-08-04T13:24:38.687" Score="10" Body="&lt;p&gt;Dismissing missiles for a moment, let's focus on fixed guns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rear-firing cannons simply make no tactical sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an enemy fighter on your six, and in gun range, you need to pitch, roll, circle, and generally maneuver like crazy to throw off his lead aim &lt;em&gt;to avoid getting shot out of the sky&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;very last thing&lt;/em&gt; you want to do is to fly in a smooth line lining him up in your (rearward) sights &lt;em&gt;while he blasts you with his (forward) cannons&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is not even taking into account that aiming the &lt;em&gt;back&lt;/em&gt; of an aircraft at a (maneuvering) target &lt;em&gt;behind&lt;/em&gt; you is an order of magnitude more difficult than aiming the &lt;em&gt;front&lt;/em&gt; of the aircraft at a target &lt;em&gt;in front&lt;/em&gt; of you.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, fixed guns are out. What about remote-controlled, swivel-mounted guns?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has actually been tried as early as in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Arado_Ar_234&quot; rel=&quot;noreferrer&quot;&gt;Arado Ar 234&lt;/a&gt;, albeit in prototypes only. You still face the issue of wasting weight and space on a weapon that can only fire at the enemy &lt;em&gt;if he's right where you do not want him in the first place&lt;/em&gt;. Speed, stealth, diversion, all these increase your chances of survival much more than pitting your rear-facing weapons against a fighter's forward-facing weapons.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So, bury the guns. At which point I'll say that I don't know enough about modern missile technology to say if modern air-air missles can or cannot actually engage targets to the rear, and bow out of the question.&lt;/p&gt;&#xA;" OwnerUserId="2401" LastActivityDate="2015-08-04T13:24:38.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17568" PostTypeId="2" ParentId="17557" CreationDate="2015-08-04T13:55:31.063" Score="3" Body="&lt;p&gt;I think as a fixed wing pilot you will will have gained fixed wing &quot;habits&quot; that are not transferable to helicopters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main one I can think of is if your engine fails on a fixed wing, you may pull to reduce the speed to best glide and gain a few hundred feet of height. This would be a disaster in an helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No doubt an helicopter pilot (of which I am not) would tell us that possibly in high speed cruise it might be possible to lose some forward speed and translate this into height, but what I am saying is that the primary consideration in an helicopter is not to lose rotor speed because the blades once stalled cannot be un-stalled (they are at the back side of the drag curve), even assuming they are undamaged at that point. So in an helicopter you drop the collective immediately to preserve rotor speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I once heard somebody say that you needed 500 hours in helicopters if you were experienced in fixed wing, before that guy would let his grandchildren fly with you.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-04T13:55:31.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17569" PostTypeId="2" ParentId="17557" CreationDate="2015-08-04T14:20:59.937" Score="3" Body="&lt;p&gt;AOPA has a &lt;a href=&quot;http://www.aopa.org/Article-Listings/Rotorcraft-Rookie&quot; rel=&quot;nofollow&quot;&gt;series of articles&lt;/a&gt; where a fixed-wing pilot learned to fly a helicopter. One of his &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2014/June/05/rotorcraft-rookie-things-i-learned&quot; rel=&quot;nofollow&quot;&gt;lessons learned&lt;/a&gt; supports the idea that it's harder to go from fixed-wing to rotary:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;There is a negative transfer of learning from airplanes&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All my aviation experience prior to flying helicopters involved a sort&#xA;  of building-blocks approach. Each new skill was based more or less on&#xA;  the previous skill. Additional class ratings simply came down to&#xA;  differences training. Such is not the case with helicopters. In some&#xA;  cases, fixed-wing knowledge is a hindrance. This is especially true&#xA;  with low-G mast bumping in the Robinson. Most poignant for me was when&#xA;  I was maneuvering for a steep approach and I saw the airspeed bleed&#xA;  off fairly quickly. My first thought was &quot;stall!&quot; when I was actually&#xA;  right where I needed to be.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But if you read the whole series, he does mention transferable skills like radio work, regulations, navigation etc. that are still useful, so while &lt;em&gt;maneuvering&lt;/em&gt; the helicopter may be more difficult for a fixed-wing pilot at first, that isn't the only consideration in learning to fly one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;https://www.google.com/search?q=harder%20to%20learn%20helicopter%20after%20fixed%20wing&amp;amp;ie=utf-8&amp;amp;oe=utf-8&quot; rel=&quot;nofollow&quot;&gt;lots of opinions&lt;/a&gt; out there about transferring from fixed-wing to helicopters, but there doesn't seem to have been any systematic analysis or investigation about it. As far as I could see, the FAA's &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/&quot; rel=&quot;nofollow&quot;&gt;Helicopter Flying Handbook&lt;/a&gt; doesn't say anything about transitioning from fixed-wing aircraft so either they didn't consider it at all or they did but decided that it wasn't a significant issue.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-04T14:20:59.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17570" PostTypeId="2" ParentId="17557" CreationDate="2015-08-04T14:50:28.740" Score="1" Body="&lt;p&gt;As a fixed-wing pilot who transitioned to rotary, I would agree that the actual &quot;stick and ruder&quot; -- or &quot;cyclic, collective, and directional pedals&quot; -- part of flying rotary wing is harder than flying an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First and foremost, there are actually three different kinds of flight in helis:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;hovering flight&lt;/li&gt;&#xA;&lt;li&gt;forward flight&lt;/li&gt;&#xA;&lt;li&gt;autorotation&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and each of these three types of flight needs to be learned individually, has its own &lt;a href=&quot;https://en.wikipedia.org/wiki/Muscle_memory&quot; rel=&quot;nofollow&quot;&gt;muscle memory&lt;/a&gt;, and its own set of gotchas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, helicopters are unstable, meaning they must be flown hands-on at all times, and helicopter trainers (e.g., Robinson, Engstrom, Schweitzer), in particular, don't have &lt;a href=&quot;https://en.wikipedia.org/wiki/Autopilot#Stability_augmentation_systems&quot; rel=&quot;nofollow&quot;&gt;stability augmentation systems&lt;/a&gt;, precisely so that the pilot learns to control the helicopter with the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, and this is more intuitive than evidentiary, &lt;a href=&quot;http://www.copters.com/helo_aero.html&quot; rel=&quot;nofollow&quot;&gt;helicopter aerodynamics&lt;/a&gt; are much more complicated than airplanes. Trainer nose-wheel airplanes can be flown quite lazily, without much rudder input, and with unsubtle control input, and not have too much an effect on the flightpath or safety of the aircraft. In a helicopter, every single input on one control (cyclic, collective, throttle, pedals) must be fully compensated for on every other control, to keep the aircraft from deviating from its flight path.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fourth, the controls on a helicopter are much more sensitive than on an airplane, and must be handled with the utmost of care. The operative phrase for handling the controls is to &quot;milk the mouse,&quot; meaning to use very small control control inputs.  (My own instructor, when I was unsubtle on the cyclic would joke &quot;Hey Bob, are you making salad?&quot;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those are the flight control issues, but there are a few other operational issues with helicopters that make them more difficult:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;helis often operate off-airport, including &lt;a href=&quot;http://www.copters.com/pilot/confined.html&quot; rel=&quot;nofollow&quot;&gt;confined area&lt;/a&gt; and pinnacle operations, operating on &lt;a href=&quot;http://www.copters.com/pilot/slope_pickup.html&quot; rel=&quot;nofollow&quot;&gt;slopes&lt;/a&gt;, operating on unimproved (or even unlandable) surfaces, all of which require specialized skills&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;helis often carry &lt;a href=&quot;https://en.wikipedia.org/wiki/Cargo_hook_(helicopter)&quot; rel=&quot;nofollow&quot;&gt;external loads&lt;/a&gt;, which adds an additional handling complexity&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-08-04T17:10:11.407" LastActivityDate="2015-08-04T17:10:11.407" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17571" PostTypeId="1" AcceptedAnswerId="17572" CreationDate="2015-08-04T15:08:59.280" Score="18" ViewCount="3780" Body="&lt;p&gt;Most reciprocating aircraft engines have two spark plugs per cylinder. What are the reasons for this?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-05T18:16:57.233" Title="Why do reciprocating aircraft engines have more than one spark plug?" Tags="&lt;piston-engine&gt;&lt;engine&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17572" PostTypeId="2" ParentId="17571" CreationDate="2015-08-04T15:13:43.987" Score="24" Body="&lt;p&gt;&lt;a href=&quot;http://www.boldmethod.com/learn-to-fly/aircraft-systems/why-do-aircraft-engines-have-2-spark-plugs-per-cylinder/&quot;&gt;Bold Method&lt;/a&gt; has a great post today about &lt;a href=&quot;http://www.boldmethod.com/learn-to-fly/aircraft-systems/why-do-aircraft-engines-have-2-spark-plugs-per-cylinder/&quot;&gt;why aircraft engines have more than one spark plug per cylinder&lt;/a&gt;. There are a few basic reasons.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Reliability&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Having two sparks plugs is more reliable. If one spark plug becomes inoperative for some reason, there's a second to provide the spark for the power stroke.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be noted that the spark plugs are usually powered by dual, independent magnetos or, in some cases, an electronic capacitor discharge ignition. The redundancy of the ignition system adds to the reliability.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;More Power&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Having two spark plugs means the flame ignites from two points leading to more power per power stroke. This point is demonstrated during run-up. When the magneto check is done the engine RPMs drop when running on a single mag and set of spark plugs.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Even Combustion&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Two sparks plugs and a two flame front leads to a more even burn of the fuel air mixture for a smoother running engine.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Prevent Fouling&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Aircraft engines burn leaded fuel which can lead to getting lead deposits on the spark plugs. Having dual plugs leads to a more complete burn which can prevent the deposits from forming.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-04T16:58:48.293" LastActivityDate="2015-08-04T16:58:48.293" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="17573" PostTypeId="2" ParentId="17564" CreationDate="2015-08-04T15:54:27.550" Score="16" Body="&lt;p&gt;Passengers' luggage is not loaded in an A380 by one suitcase at a time. That would be very time consuming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After passengers check in the luggage and head towards the gate where the superjumbo is parked, their baggage is started to get stored in &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;unit load devices&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt;. And after that, those ULDs are loaded into the airplane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NvDUS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NvDUS.jpg&quot; alt=&quot;ULD stored in airplane&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Unloading_JAL_747.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a380family/specifications/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus&lt;/a&gt;, the A380 can store 38 LD3s. Volume of a typical suitcase/bag (dimensions: 32&quot;H x 12&quot;W x 21&quot;D) is less than 5 cubic feet, so 30 suitcases can easily fit in a single LD3.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now let's talk about your questions about loading and unloading times. As A380s mostly fly on international routes, passengers are required to check in several hours before a flight's departure. But once they check in their luggage, the process of loading those LD3 starts, even if the airplane has not yet arrived at the gate. As soon as the airplane reaches the gate, unloading and loading processes start. These two processes are not as time consuming as they may appear&lt;sup&gt;2&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers' checked in luggage is not loaded like in this manner (picture below). On a wide-body like an A380, this is the case of carry-on baggage which stored in the underfloor area, instead of overhead bins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qpC59.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qpC59.jpg&quot; alt=&quot;Baggage loading&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://time.com/12835/travelers-its-about-damn-time-airlines-toughened-up-baggage-policies/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;: A380 uses LD3, whose capacity is 159 cubic feet.&lt;br&gt;&#xA;&lt;sup&gt;2&lt;/sup&gt;: Note that after an LD3 is unloaded from an airplane, it might take another hour or even more for the passengers to get their luggage at the baggage claim area.&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="13197" LastEditDate="2020-02-21T16:41:22.333" LastActivityDate="2020-02-21T16:41:22.333" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="17574" PostTypeId="1" AcceptedAnswerId="17580" CreationDate="2015-08-04T16:02:54.830" Score="4" ViewCount="934" Body="&lt;p&gt;When I read through IFR materials online, or when I hear pilots talking about approaches, they often talk about using fixes to get to/through the approach.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two questions (closely related):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Firstly, just to make sure I completely understand, what are fixes in this particular context?&lt;/li&gt;&#xA;&lt;li&gt;Secondly, how are they used when a pilot is using a particular approach?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="65" LastEditDate="2015-08-04T17:08:15.360" LastActivityDate="2015-08-04T19:52:10.210" Title="How are fixes used during an approach?" Tags="&lt;landing&gt;&lt;approach&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17575" PostTypeId="2" ParentId="17574" CreationDate="2015-08-04T17:24:17.187" Score="2" Body="&lt;p&gt;A &lt;em&gt;fix&lt;/em&gt; is a point is space that defines a &lt;em&gt;segment&lt;/em&gt; of an approach. You can think of it like an intersection on a street map that defines the approach. So when someone says &quot;Take Jones Road to Main Street and Turn left. Then go one block and turn right onto Broadway&quot; you can think of Jones &amp;amp; Main and Main &amp;amp; Broadway as two fixes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation terms such as the approach below, there are fixes named &lt;em&gt;DIVEC, PONKE, WETOR, ROKMO, HEMAN, DUYET, NEPIC, and I-SFO&lt;/em&gt;, which the pilot follows to get to the intended airport. &lt;img src=&quot;https://i.stack.imgur.com/UPPlB.png&quot; alt=&quot;plate&quot;&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-04T17:24:17.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17576" PostTypeId="2" ParentId="17564" CreationDate="2015-08-04T18:25:33.657" Score="10" Body="&lt;p&gt;Another Airbus &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-Dec2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;document&lt;/a&gt; mentions (on page 188, section 5-2-1) full load of A380 as&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;FWD cargo compartment: 20 containers&lt;/li&gt;&#xA;  &lt;li&gt;AFT cargo compartment: 16 containers&lt;/li&gt;&#xA;  &lt;li&gt;Bulk cargo compartment: 1,000 kg (2,205 lb).&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and rate of loading and unloading as &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Container unloading/loading times:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Unloading = 1.2 min/container&lt;/li&gt;&#xA;  &lt;li&gt;Loading = 1.4 min/container.&#xA;  Bulk unloading/loading times:&lt;/li&gt;&#xA;  &lt;li&gt;Unloading = 110 kg/min (243 lb/min)&lt;/li&gt;&#xA;  &lt;li&gt;Loading = 95 kg/min (209 lb/min).&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From this calculation best case is they can finish unloading and loading within just above 30 minutes. However this is not possible since there will be some delay due to the fact that there are other things to be done during turn around that may disrupt exchange of cargo. Also other services such as cleaning need to be done during turn around time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus provides 2 scenarios for turn around time &#xA;&lt;br&gt; - 90 minutes if both decks are serviced at the same time.&#xA;&lt;br&gt; - 140 minutes if both decks are serviced only from the main deck.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="14897" LastEditDate="2018-06-12T23:34:59.033" LastActivityDate="2018-06-12T23:34:59.033" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17577" PostTypeId="2" ParentId="17574" CreationDate="2015-08-04T18:26:37.883" Score="2" Body="&lt;p&gt;Fixes are in some ways like VRPs (visual reporting points when VFR). You fly to a fix, then fly a particular pattern away from the fix in a very tightly controlled, direction, speed and height designed to get you to close to the threshold at the correct speed and height. The exact pattern will be different depending on the type of approach you are using - each runway at an airport may have more than one, although depending on runway in use, only one approach will usually be in use at one time unless say you have an ILS failure in the aircraft and have to use an alternative. I'll let somebody who is instrument current explain an example, they will do a much better job than I can right now.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-04T18:26:37.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17578" PostTypeId="1" CreationDate="2015-08-04T19:13:58.203" Score="7" ViewCount="737" Body="&lt;p&gt;With quite a few concept designs in progress, I am curious what the current FAA regulations are regarding vertical takeoff and landing vehicles in the light sport aircraft category.&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2019-10-07T02:26:01.613" Title="What is the current state of regulation regarding VTOL aircraft in the LSA category?" Tags="&lt;faa-regulations&gt;&lt;light-sport-aircraft&gt;&lt;vtol&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17579" PostTypeId="1" AcceptedAnswerId="17582" CreationDate="2015-08-04T19:37:32.043" Score="8" ViewCount="2249" Body="&lt;p&gt;In aviation we often refer to the bank of a turn as shallow, medium  or steep. I remember reading somewhere that the definition is not universal as to how many degrees it is, but it has to do with the airplane and whether the bank tends to roll back to level, remain where it is or continue to steepen. Does anyone know if this is a correct definition or have any references to share?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-04T20:11:56.657" Title="How is the steepness of turn bank properly defined?" Tags="&lt;maneuver&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17580" PostTypeId="2" ParentId="17574" CreationDate="2015-08-04T19:40:40.507" Score="5" Body="&lt;p&gt;What a fix is has been answered &lt;a href=&quot;https://aviation.stackexchange.com/q/16171/62&quot;&gt;here&lt;/a&gt; but for now let's just say it's a known location that a pilot can navigate to if he has the right equipment. Fixes are shown on various charts and approach plates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for using those fixes on an instrument approach, there are lots of variations and details but again, let's ignore most of that for now. The basic concept is very simple:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Fly to an Initial Approach Fix (IAF)&lt;/li&gt;&#xA;&lt;li&gt;Fly to other fixes as needed to execute the approach&lt;/li&gt;&#xA;&lt;li&gt;Land (or go missed)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For example, here's the RNAV (GPS) 36R approach at &lt;a href=&quot;http://www.airnav.com/airport/KHSV&quot; rel=&quot;nofollow noreferrer&quot;&gt;KHSV&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pJNzd.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pJNzd.png&quot; alt=&quot;KHSV RNAV (GPS) 36R&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see at the bottom of the map portion of the plate that both MASHA and FEWER are IAFs, so that's where the approach starts. Let's say you're approaching from the south-west and you've already descended to a reasonable altitude for starting an approach, following a &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_terminal_arrival_route&quot; rel=&quot;nofollow noreferrer&quot;&gt;STAR&lt;/a&gt; or vectors from ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC says something like &quot;N12345 proceed direct MASHA, cleared for the RNAV 36R approach&quot;. That means that you are now cleared to execute the approach as shown on the chart, with no further instruction from ATC (although they might have vectored you towards the IAF initially).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chart tells you that at MASHA you need to be at at least 3000ft MSL so you simply fly there at or above that altitude. Since it's a GPS approach, you load it and activate it in your GPS unit, and you can follow the GPS track to MASHA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After MASHA, the next fix is ENIKY and the GPS track will lead you east to that fix (which is a heading of 091° from MASHA). The profile view at the bottom of the plate shows that you must still be at or above 3000ft at ENIKY. Then you turn left to 002° and fly to UJOTY, where you must be at or above 2700ft. Then you continue to GEPDE at or above 1180ft. Then you land :-) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, I'm ignoring a huge amount of detail here - like everything else printed on the approach plate! - but since this question is about fixes the main point is that they're simply a series of waypoints that you fly over (&lt;a href=&quot;https://aviation.stackexchange.com/q/11681/62&quot;&gt;or past&lt;/a&gt;) to get to the runway. And obviously you also have to control your altitude as you descend, but the altitude is defined by the approach procedure, it isn't part of the definition of the fix itself. The same fix can be used in multiple approaches: MASHA and FEWER are also the IAFs for the &lt;a href=&quot;http://155.178.201.160/d-tpp/1508/05488R36R.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;RNAV (GPS) 36L approach&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though different approaches define and use fixes in different ways, the basic idea is always the same: just fly from one fix to the next until you get where you're going.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-08-04T19:52:10.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17581" PostTypeId="2" ParentId="17574" CreationDate="2015-08-04T19:42:54.693" Score="1" Body="&lt;p&gt;A fix is a virtual position that helps aircraft maintain their flight plan. It is usually defined as the intersection (in the geometrical sense) of two VOR radials, but other navigational aids such as GPS or even radar can be used to identify one of these positions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most basic use of fixes are to define a flight path using one or more fixes. The flight path is usually direct between two fixes but there are exceptions like the DME arc. Not only do fixes identify a flight path, but they can also be used to denote a position where a new altitude can be descended to. For example, on an approach an aircraft may have to maintain 7000 feet as is the case with DIVEC, but may descend to 6000 feet after passing DIVEC on the way to PONKE. In short, fixes are used to establish both the horizontal and vertical flight paths of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UPPlB.png&quot; alt=&quot;approach plate&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-04T19:42:54.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17582" PostTypeId="2" ParentId="17579" CreationDate="2015-08-04T19:44:34.890" Score="8" Body="&lt;p&gt;I don't know if this is only definition out there, but according to the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/&quot;&gt;FAA's Airplane Flying Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Shallow turns are those in which the bank (less than approximately&#xA;  20°) is so shallow that the inherent lateral stability of the airplane&#xA;  is acting to level the wings unless some aileron is applied to&#xA;  maintain the bank.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Medium turns are those resulting from a degree of bank (approximately&#xA;  20° to 45°) at which the air- plane remains at a constant bank.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Steep turns are those resulting from a degree of bank (45° or more) at&#xA;  which the “overbanking tendency” of an airplane overcomes stability,&#xA;  and the bank increases unless aileron is applied to prevent it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-04T19:44:34.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17583" PostTypeId="2" ParentId="17579" CreationDate="2015-08-04T20:11:56.657" Score="-1" Body="&lt;p&gt;Also very closely related is the turning radius, which also depends on the speed. For example, a Rate 1 turn is defined as a turn that changes the aircraft heading 3 degrees per second, so it takes 2 minutes (120 seconds) to turn a full 360 degree circle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in an ultralight, doing 50 knots, you need approx. 50 / 10 = 5 + 7, or 12 degrees of bank to achieve a full circle in 2 minutes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in a 747 flying at 180 knots, you need 180 /10 = 18 + 7, or 25 degrees of bank to achieve a full circle in 2 minutes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both turns might be classed as &quot;shallow&quot; (although on that definition I would hate to do a steep turn in a 747).&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-04T20:11:56.657" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17585" PostTypeId="2" ParentId="16995" CreationDate="2015-08-04T21:33:03.677" Score="5" Body="&lt;p&gt;Welding has 2 significant drawbacks (1) it generally weakens the parent material the heat in affected zone and (2) use of a single component can lose crack stopping at the change from one section to the next. I heard a story that someone (Lockheed?) had tried the use of diffusion bonding but then suffered major crack development during structural testing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having had access to the Comet fuselage used for water tank pressure testing (mounted on the wall of a lab at RAF College Cranwell) the growth of cracks is clearly apparent. In the past, engineers used to drill holes at the end of a crack (when they found them) because the increased tip radius slows the rate of propagation. My father and godfather were both Imperial Airways engineers in the 1930's, 40's and 50's. (OK, the name changed to BOAC i 1940.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it is almost impossible to test the integrity of a weld without breaking it; like the match factory that tests 100% and only despatches the ones that worked.&lt;/p&gt;&#xA;" OwnerUserId="9683" LastActivityDate="2015-08-04T21:33:03.677" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17586" PostTypeId="2" ParentId="17571" CreationDate="2015-08-04T22:29:10.310" Score="5" Body="&lt;p&gt;Engine Longevity as well. The more even combustion resulting from dual sparks prevents hot spots inside the cylinder, resulting in improved engine life.&lt;/p&gt;&#xA;" OwnerUserId="9684" LastActivityDate="2015-08-04T22:29:10.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17588" PostTypeId="2" ParentId="17374" CreationDate="2015-08-04T23:59:35.450" Score="1" Body="&lt;p&gt;A simple reason is that airlines have found another way to carry a large number of passengers at a smaller cost: the seat density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrary to what was expected, the trend is not to sell more comfortable seats. This hits both Boeing and Airbus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.fool.com/investing/general/2015/03/01/why-boeing-747-and-airbus-a380-sales-are-few-and-f.aspx&quot; rel=&quot;nofollow&quot;&gt;Why buy a gigantic Airbus A380 or Boeing 747 when you can squeeze more seats into a smaller plane instead?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This low-cost market trend coincides with the uncertain future of hubs at large airports, the trend being to see an increase in direct (and smaller) trips ratio.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-08-05T00:11:07.303" LastActivityDate="2015-08-05T00:11:07.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17590" PostTypeId="2" ParentId="7" CreationDate="2015-08-05T02:44:51.460" Score="9" Body="&lt;p&gt;Some aircraft don't have enough elevator authority to enter a real stall if the have a nose heavy CG. The wing fails to achieve the required angle of attack, and the plane mushes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution for these kids of planes is not to enter the stall from MCA, as is typically taught. Rather, enter from straight and level flight at Vx, and break into a full stall by sharply moving the yoke to its full aft position.  This should result in a significant nose-up attitude and exceed the critical angle of attack, and you will see and feel a sharp break. Remain coordinated throughout the maneuver, and recover by releasing back pressure, and don't let the nose get too low. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This method can also be adopted for aircraft that don't have enough  elevator authority to do a turning stall.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're doing this in a power plane (rather than a glider), you'll probably wind up adding power in the recovery.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-08-06T20:08:58.250" LastActivityDate="2015-08-06T20:08:58.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17591" PostTypeId="1" CreationDate="2015-08-05T08:08:54.283" Score="25" ViewCount="9782" Body="&lt;p&gt;Since &lt;a href=&quot;https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot;&gt;MH370&lt;/a&gt; was a &lt;a href=&quot;https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370&quot;&gt;Boeing 777&lt;/a&gt;, why are they taking the suspected wing flaperon to &lt;a href=&quot;https://en.wikipedia.org/wiki/Toulouse&quot;&gt;Toulouse&lt;/a&gt;, France?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are some spare parts made by Airbus?&lt;/p&gt;&#xA;" OwnerUserId="9688" LastEditorUserId="849" LastEditDate="2015-08-06T13:23:15.947" LastActivityDate="2015-08-06T13:51:16.923" Title="Why is a part from a Boeing 777 being analysed by Airbus?" Tags="&lt;mh370-incident&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17592" PostTypeId="2" ParentId="17591" CreationDate="2015-08-05T08:17:09.180" Score="69" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why are they taking the wing to Toulouse, FR?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because the part was found on the island of &lt;a href=&quot;https://en.wikipedia.org/wiki/R%C3%A9union&quot;&gt;Réunion&lt;/a&gt;, which is French territory.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why is a part from a B777 being analysed by Airbus?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It is not&lt;/strong&gt;. Airbus is not the only company/institution to have plants/facilities in Toulouse: &lt;a href=&quot;http://www.bea.aero/en/&quot;&gt;The BEA&lt;/a&gt; (France's equivalent to the NTSB) also has facilities there.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="64" LastEditDate="2015-08-05T16:04:28.427" LastActivityDate="2015-08-05T16:04:28.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17593" PostTypeId="1" CreationDate="2015-08-05T08:20:00.123" Score="3" ViewCount="443" Body="&lt;p&gt;This is more in relation to flights which have a single class of passengers with a short haul flight duration. Why don't airlines adopt random seating arrangement i.e. first come first serve basis. We already see business class passengers of having the flexibility of boarding at their own convenience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might solve the problem of boarding, and might also encourage people to board quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To solve the issue of cabin baggage, we could have dedicated space for each passenger, by dividing the existing baggage space by the number of seats below. This would take care of 'greedy' passengers. Also, passengers can check beforehand if they are carrying excess luggage.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="609" LastEditDate="2015-08-05T09:40:41.533" LastActivityDate="2015-08-05T18:07:47.890" Title="Would random sitting arrangement be the best way of boarding for passengers?" Tags="&lt;boarding&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17594" PostTypeId="2" ParentId="17591" CreationDate="2015-08-05T08:29:09.617" Score="39" Body="&lt;p&gt;To extend a bit on Federico's answer. As I understand, &lt;a href=&quot;http://www.bea.aero/en/&quot; rel=&quot;noreferrer&quot;&gt;BEA&lt;/a&gt;, the French accident authority, have some office in Toulouse while the facility itself where it will be looked at is military.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;France's BEA crash investigation agency will examine the wing flap at the Direction Generale de l'Armement compound near Toulouse. &lt;a href=&quot;http://www.japantimes.co.jp/news/2015/07/31/world/mh370-trail-now-leads-france-investigators-will-probe-plane-debris/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also from the BEA website, under the heading ICAO:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In particular, &lt;strong&gt;States must start an investigation in case of a civil aviation accident or serious incident on their territory.&lt;/strong&gt; It is specified that &amp;quot;The sole objective of the investigation of an accident or incident shall be the prevention of accidents and incidents&amp;quot; and that &amp;quot;It is not the purpose of this activity to apportion blame or liability&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;Close association between the representatives of the States of Registry, Operation, Design and Manufacture of the aircraft is organised. This brings to the State that is leading the investigation useful skills and information and allows for feedback that is as fast and complete as possible in terms of safety. &lt;a href=&quot;http://www.bea.aero/en/bea/qui-sommes-nous/cadre-juridique.php&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Which explains their responsibility in investigating the part. I don't think there are too many facilities with extensive knowledge of forensic engineering on impact-damaged (composite) parts (Even analysis of damaged Black Boxes is often 'outsourced') so they might even be happy to have the large BEA look at it.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;The French are not unfamiliar with investigating aircraft accidents and have participated in a few substantial ones in the last few years. I discovered presumably the &lt;a href=&quot;http://www.flightglobal.com/news/articles/wreckage-of-af447-transferred-as-recovery-effort-ends-357850/&quot; rel=&quot;noreferrer&quot;&gt;same folks&lt;/a&gt; were involved in forensic engineering work of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;AF447&lt;/a&gt; remains in 2011, which also crashed into the ocean.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;French investigation agency Bureau d'Enquetes et d'Analyses said the vessel would transfer to Bayonne, a port on the south-western coast, and parts from flight AF447 would be moved to a hangar in Toulouse.&lt;/p&gt;&#xA;&lt;p&gt;The wreckage would be examined by the French defence ministry's technical aeronautical division. The recovery effort also retrieved several victims of the crash and these will be taken for forensic assessment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Footnote: Since accidents with unclear events (or presenting controversial claims like crashing the plane) such as this one which can be a hot potato it is sometimes even desired to have a independent third party look at the stuff.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-06T13:51:16.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17595" PostTypeId="2" ParentId="17593" CreationDate="2015-08-05T09:18:46.993" Score="4" Body="&lt;p&gt;Unless I misunderstand you, many airlines already do this. You buy a ticket, you join a queue and you sit in the first available seat that is acceptable to you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find it leads to fitter younger people sprinting to the front and leaving the old and frail with the worst seats. Some airlines prioritize boarding for adults accompanying children and a few other categories. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As ManuH commented. Unallocated seating often leads to families being separated inside the cabin and sometimes to prolonged multi-way pre-take-off negotiations with other passengers to try to arrange swaps to get a seat in the same general region of the plane as your loved ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I find a preallocated seat number and boarding prioritised by row number leads to a  more civilised experience and fewer scrums arise in the aisles as prior passengers try to stuff luggage into overhead lockers above seats near the doors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many ways of defining &quot;best&quot;, speed of boarding is only one of them. This is perhaps why no airline yet bales up their passengers and loads them by forklift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recall the USAF has seats attached to freight pallets that it uses for troop transport, maybe the future of aviation is to be strapped into your seat in the departure lounge and be mechanically loaded from one end of the fuselage?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-05T10:32:58.810" LastActivityDate="2015-08-05T10:32:58.810" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17596" PostTypeId="1" AcceptedAnswerId="17598" CreationDate="2015-08-05T09:20:19.080" Score="19" ViewCount="4614" Body="&lt;p&gt;As I understand from &lt;a href=&quot;http://www.bbc.co.uk/programmes/b01l1w71&quot; rel=&quot;noreferrer&quot;&gt;those&lt;/a&gt; &lt;a href=&quot;https://www.youtube.com/watch?v=HHxTZXY3mPQ&quot; rel=&quot;noreferrer&quot;&gt;videos&lt;/a&gt;, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_maintenance_checks#D_check&quot; rel=&quot;noreferrer&quot;&gt;D-check&lt;/a&gt; basically consists in disassembling the whole aircraft, inspecting every little piece, and then reassembling it. For me, the last part seems to be more or less the job of aircraft builders, and thus its costs may be comparable to the lasts steps of building an aircraft. Thus the cost of a few D-checks may be the same as building an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Counted in D-checks cost, how many D-checks does a newly built aircraft cost?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's focus on airliners. If needed, the question may be narrowed down to best sellers (lets say B737 and A320).&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="64" LastEditDate="2015-10-30T02:54:12.483" LastActivityDate="2015-10-30T02:54:12.483" Title="How much does a D-check cost compared to a new aircraft?" Tags="&lt;airliner&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17597" PostTypeId="2" ParentId="9955" CreationDate="2015-08-05T13:53:37.913" Score="0" Body="&lt;p&gt;Velocity is an instantenous phenomenon. It exists at a point.(lets ignore Average velocity here, it isn't necessary that we discuss it for this question.) At the stagnation point, the velocity is 0. However, at a distance dx from the stagnation point, the fluid particle again gains momentum. It sort of is like a pendulum. At the highest point its velocity is zero, but after a differential time dt, it again regains its velocity and starts to move. You see fluid particles like a pendulum need a stimulus to do so, in the case of pendulum its gravity, for a fluid particle, it can be anything from a pressure force to inertia&lt;/p&gt;&#xA;" OwnerUserId="9694" LastActivityDate="2015-08-05T13:53:37.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17598" PostTypeId="2" ParentId="17596" CreationDate="2015-08-05T15:41:38.430" Score="19" Body="&lt;p&gt;Keep in mind that during a D check, the parts on the plane are already owned. There will of course be a certain amount of parts replaced, but it will be much less than the manufacturer's cost to buy/manufacture all of the parts. There will be thousands of hours of labor, which will be most of the cost of a D check. The cost of maintenance space and taking the plane out of revenue service may also be considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://books.google.com/books?id=OL5e45O2NmUC&amp;amp;lpg=PA156&amp;amp;ots=dOVBs7qBf4&amp;amp;pg=PA157#v=onepage&quot;&gt;this financial reference&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For a 15-year old Boeing 737-300, a D check would likely cost &lt;strong&gt;\$1.25-\$1.5 million&lt;/strong&gt;, representing about &lt;strong&gt;8-10% of the cost of the aircraft&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This book is now 15 years old along with the newest 737-300's, so in today's dollars this would be &lt;strong&gt;\$1.73-\$2.08 million&lt;/strong&gt;, not accounting for changes in the cost of maintenance. Larger aircraft will have larger costs. This seems to put the cost in the same range as &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/175232/&quot;&gt;other sources&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-08-05T15:41:38.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17599" PostTypeId="2" ParentId="17593" CreationDate="2015-08-05T17:04:36.700" Score="5" Body="&lt;p&gt;The Mythbusters tested various boarding patterns in their previous season (&lt;a href=&quot;https://www.youtube.com/watch?v=ss1S3-Kv6R8&quot; rel=&quot;nofollow&quot;&gt;see the digest here&lt;/a&gt;, &lt;a href=&quot;https://www.youtube.com/watch?v=x5O31O2TJdY&quot; rel=&quot;nofollow&quot;&gt;full episode here&lt;/a&gt;) and came to the conclusion that &quot;random-random&quot; (close to Southwest-style) was the fastest way to board (though the least liked), and that the current most common method among traditional airlines (back to front) was the slowest. Alternate styles including two forms of &quot;WILMA&quot; boarding (Window-Middle-Aisle, United does this) and &quot;Reverse Pyramid&quot; style (which U.S. Airways used to use) were both fast and very well-liked by the volunteers. I have some issues with their testing methods though:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They only allowed for a single test of each boarding plan, using the same group of volunteers each time. That means two things:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Order of testing matters, because your group will generally become accustomed to getting on and off a plane, which will speed things up as the day progresses.&lt;/li&gt;&#xA;&lt;li&gt;Any &quot;noise&quot; inherent in a variable of the test that you are neither controlling nor testing cannot be cancelled out and can skew the results.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;They tested the control (back to front) first, meaning their volunteers were totally unfamiliar with the &quot;plane&quot; and thus would be expected to be slowed by inefficiencies born of this unfamiliarity. If no other test were repeated, it should have been this one (at the beginning and end of the day) to compensate for this.&lt;/li&gt;&#xA;&lt;li&gt;First/business class were always boarded first (this is common but not universal among airlines), while every other ticketed passenger regardless of age was boarded according to their individual seat, with only &quot;lap children&quot; boarding with their parent (airlines nowadays require a ticket and seat for anyone over 2yo, so boarding families with pre-adolescents was not really tested). This is opposed to other variables such as overloaded passengers, guys heading &quot;upstream&quot; to the lavatory etc which they sprinkled in to spice up each boarding experience.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One final thing; boarding faster only means you're sitting in a cramped airliner seat longer. Getting passengers aboard an airplane is usually the easiest and quickest part of turning an airliner around. Unloading/loading baggage, refueling, preflight checks etc all take longer in the aggregate than anything going on inside the cabin.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-05T18:07:47.890" LastActivityDate="2015-08-05T18:07:47.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17600" PostTypeId="2" ParentId="7" CreationDate="2015-08-05T17:34:55.420" Score="1" Body="&lt;p&gt;My last flight involved some stall training in a PiperSport LSA, and it actually did take considerable conscious input to make the plane move past that &quot;mushy&quot; stage and depart completely (it would nose down quite handily when you did though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I concur with other answers; there is a difference between a &quot;stall&quot; (exceeding critical angle of attack and thus losing lift and/or full attitude control) and a &quot;departure&quot; (losing most or all attitude control). If pulling back on the stick or yoke won't continue to pitch the nose up, you've stalled, but you haven't departed completely until you can't push the nose back down (or it noses down even with full nose-up elevator applied).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many small planes with &quot;normal&quot; or &quot;utility&quot; category ratings (or &quot;limited&quot; light-sports) are designed with a large amount of &quot;departure resistance&quot;; their aerodynamic design and mass distribution makes it hard to fully depart the aircraft and enter a nose-down stall (or a spin, spiral dive etc). This also makes intentional maneuvering near the edges of the flight envelope more difficult, as the plane will want to settle back into a stable configuration rather than let the pilot potentially push further into departure.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-05T17:42:28.943" LastActivityDate="2015-08-05T17:42:28.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17601" PostTypeId="2" ParentId="17571" CreationDate="2015-08-05T17:57:13.910" Score="3" Body="&lt;p&gt;Reliability is the key thing. The ignition system of a gasoline engine (the &quot;magnetos&quot; in most aircraft) is absolutely critical to the engine's operation, and thus the safety of the flight of the aircraft possessing it. A small break in a wire, or fouling of one plug, could cause cylinder misfires or even a total engine failure. To guard against this, dual independent ignition systems are incorporated into aviation engines to allow for continued operation in the event that any component of one ignition system fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Efficiency is a secondary benefit. Two spark plugs per cylinder means the spark initiates combustion at two points within the volume of the cylinder. Combustion rate of a vaporized fuel is typically a function of &quot;surface area&quot; of the region of combustion, so two sparks equals double the combustion surface area. This produces faster and more complete combustion, increasing power at a given fuel flow rate. One of the rudimentary &quot;runup&quot; tests of a piston engine involves selecting one or the other magneto, and watching the performance of the engine. The normal result with a healthy ignition system is a slight reduction in power, as indicated (in a fixed-pitch prop at least) by lower RPM. A severe power reduction, rough operation or an engine quit is a sign something's wrong on that side of the ignition system.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-05T18:16:57.233" LastActivityDate="2015-08-05T18:16:57.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17602" PostTypeId="2" ParentId="7" CreationDate="2015-08-05T19:42:05.103" Score="2" Body="&lt;p&gt;There are some very good answers here, I enjoyed reading this post. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would just like to add in a lot of aircraft, if you are aggressive on the rudder (in order to keep in balance at all costs, i.e. every time a wing moves slightly down you step on the sky), it is very difficult to enter a spin. The opposite is also true, if you are flying along in mushing flight and give the rudder a good kick a spin is often the result. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different aircraft will handle differently in this mode, in some like the 182 it will be relatively easy to stay there, others could end up in a spin if the smallest of mistakes were made. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alan Bramson used to call the aeroplane a &quot;tin parachute&quot; when in this mode and I believe in the olden days it was used to descend rapidly through holes in clouds (!) without building up too much speed. Although its not really a parachute because if you hit the ground in this mode the sink rate would usually be so high (in excess of 500 feet per minute), the ground would obliterate you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To fully answer the other half of this question I think its most probably CG related and that being a new aircraft its easier than normal to keep in balance being very clean etc.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2017-10-18T09:59:02.527" LastActivityDate="2017-10-18T09:59:02.527" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17603" PostTypeId="2" ParentId="16669" CreationDate="2015-08-05T20:34:37.413" Score="0" Body="&lt;p&gt;Maybe you should change your instructor! If the second instructor agrees with the first one then you need to work really hard on the areas they are highlighting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not a professional airline pilot but I am an enthusiast and have flown big jet full motion simulators both airliners and fighters. The hardest aircraft you will fly are small light aircraft in general and particularly IFR, when you are getting tossed around in a bumpy cloud, on your own, with nobody to help you but yourself and its taking you half of your concentration just to keep the wings level. The larger ones are easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say that your attitude and your approach to your work and your decision making, your ability to think and stay calm, etc etc. is more important than this thing you call &quot;talent&quot;. Some people appear to be born with &quot;talent&quot; which just means they pick things up quicker, but this is nothing that hard work cannot replace. You have just got to want it enough and put enough effort in. Good luck!&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-05T20:34:37.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17604" PostTypeId="2" ParentId="11550" CreationDate="2015-08-05T21:26:15.740" Score="3" Body="&lt;p&gt;Frost does form if you fly into cloud with the correct temperature and moisture levels as explained elsewhere. It can bring planes down if not protected by anti ice systems or where such systems are not used correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, be wary of taking off with frost on your aircraft. It could have unknown effects on the stall speed and aerodynamic qualities of your aircraft (in other words it might not fly). For example if you have frost on one wing only, or the tail, the outcome might be very bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, faster aircraft such as jets have higher skin temperatures on the leading edges due to friction from the speed. They still need anti icing systems though. Taking to extremes the Lockheed SR-71 Blackbird had skin temperatures of 200 degrees C + when flying at Mach 3. It would also be above most of the clouds that could form ice at that point (not sure of the situation though when it was at 30,000 feet refuelling).&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-05T21:26:15.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17605" PostTypeId="1" AcceptedAnswerId="17616" CreationDate="2015-08-05T23:29:04.817" Score="15" ViewCount="14663" Body="&lt;p&gt;For a layman like I am, both the planes look massive and similar in size and shape, as if a near copy of each other. Do the similarity only end in the size and shape? Do they not perform equally well in similar roles? &lt;strong&gt;While Boeing 747 is used for commercial airlines, why isn't Lockheed C-5 Galaxy? Similarly, why is C-5 galaxy popular for Military and 747 isn't?&lt;/strong&gt; &lt;/p&gt;&#xA;" OwnerUserId="9659" LastEditorUserId="14897" LastEditDate="2020-04-22T11:04:50.357" LastActivityDate="2020-04-22T11:04:50.357" Title="Why is C-5 Galaxy not used for commercial airlines while Boeng 747 is?" Tags="&lt;military&gt;&lt;commercial-aviation&gt;&lt;boeing-747&gt;&lt;lockheed-c-5&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17607" PostTypeId="2" ParentId="17605" CreationDate="2015-08-06T01:52:52.380" Score="3" Body="&lt;p&gt;&lt;strong&gt;While Boeing 747 is used for commercial airlines, why isn't Lockheed C-5 Galaxy?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-5 was created on a proposal made directly to the military to fill a heavy lift role. It is more rugged than a 747 and includes things that only military operations call for like countermeasures and probably lot of other classified systems. It's uniquely suited for evasive maneuvers and down range operations that a 747 wasn't designed for. It's specifically a military aircraft with no civilian version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Similarly, why is C-5 galaxy popular for Military and 747 isn't?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 is popular for military use, but mostly in the form of contract work. The military hires private companies to move cargo with 747s all the time. The military does have some 747s of their own too. The E-4 is one example. And there's always Air Force One.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-06T01:52:52.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17608" PostTypeId="1" CreationDate="2015-08-06T02:07:39.023" Score="11" ViewCount="4836" Body="&lt;p&gt;I live near O'Hare airport and see hundreds of planes every day.  This evening a plane flew past that did not have the standard red - green wing tip lights.  It was white only on both sides.  It caught my attention because of that, and because the plane was unusually quiet...not silent, but quieter than most everything accept the smallest private planes.  Any suggestions as to what I saw?&lt;/p&gt;&#xA;" OwnerUserId="9699" LastEditorUserId="62" LastEditDate="2015-08-06T02:29:11.973" LastActivityDate="2020-07-03T09:26:47.300" Title="What aircraft might have white wing tip lights?" Tags="&lt;aircraft-identification&gt;&lt;aircraft-lighting&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17610" PostTypeId="1" AcceptedAnswerId="17615" CreationDate="2015-08-06T05:50:43.583" Score="5" ViewCount="924" Body="&lt;p&gt;Using my ADS-B receiver, In the past few months I've seen a lot of what I think are TIS-B contacts.  They seem to cycle through a few different ICAO ID prefixes, but I see a lot that are of the form (in hex) 29xxxx and 31xxxx. E.g. 298c12 and 318512.  I'm looking for a specification of exactly which ranges of ICAO codes can be used for TIS-B.&lt;/p&gt;&#xA;" OwnerUserId="3037" LastEditorUserId="19" LastEditDate="2015-08-06T08:23:58.897" LastActivityDate="2020-05-21T13:37:35.127" Title="What ICAO codes are reserved for TIS-B use?" Tags="&lt;icao&gt;&lt;ads-b&gt;&lt;tis-b&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17611" PostTypeId="2" ParentId="17608" CreationDate="2015-08-06T06:00:51.010" Score="14" Body="&lt;p&gt;You don't tell us if you're viewing this aircraft from the front (approaching you) or the back (moving away from you), so let's look at all the options:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft have three colors of steady-burning navigation/position lights: Red on the left (port) side, Green on the right (starboard) side, and White at the aftmost position (tail). This diagram shows the required lighting coverage (as implemented on a typical small aircraft):&#xA;&lt;a href=&quot;http://learntofly.ca/aircraft-navigation-lights/&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XfBlZ.jpg&quot; alt=&quot;Position Lights&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(With the exception of a &quot;mast light&quot; these are identical to naval vessel position lights - the function of a mast light is performed by the landing light, though it's not used as a &quot;position light&quot; the way the others are.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On some aircraft there will also be aft-facing white position lights on the wingtips, combined with the navigation and strobe lights:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/t0B58.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t0B58.gif&quot; alt=&quot;Nav/Position/Strobe combo light&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;The aft-facing position lights on the wingtip improve visibility at night, particularly flying over brightly lit urban areas (a problem sailing vessels don't have). They also give a visual reference to determine the size (wingspan) of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally (just to throw another wrench in the works) some aircraft are equipped with wingtip &quot;recognition lights&quot; (forward-facing white lights on the wingtip):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0usAt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0usAt.jpg&quot; alt=&quot;Recognition/Nav/Strobe lights&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;These are typically used on the ground or in approach to landing, but when illuminated the brighter recognition lights can make the forward position lights difficult to see, particularly from the ground where your eyes probably aren't adapted for darkness.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So putting it all together:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're viewing the aircraft from the rear (it's flying away from you) you will only see white lights (either one or three white lights) and the aircraft's strobes or other intermittent anti-collision lights. You will thus know the aircraft is traveling away from you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're viewing the aircraft from the front (it's flying directly toward you) you will see a red and green light (possibly with white taxi/landing/recognition lights as well, but the red and green at the wingtips are what you're looking for to identify the aircraft's direction of travel).&lt;br&gt;&#xA;Again if the aircraft has wingtip &quot;recognition lights&quot; you may have trouble picking out the navigation lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're viewing the aircraft from the side (it's flying perpendicular to you) you will see either the Red or Green light until it passes in front of you, at which point one (or more) of the white lights will come into view.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-06T06:00:51.010" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17612" PostTypeId="1" AcceptedAnswerId="17617" CreationDate="2015-08-06T07:01:32.650" Score="11" ViewCount="3921" Body="&lt;p&gt;Luggage is loaded into containers, in Wide Body airliners (as mentioned &lt;a href=&quot;https://aviation.stackexchange.com/questions/17564/what-is-the-average-time-taken-to-load-and-unload-the-luggage/17573#17573&quot;&gt;here&lt;/a&gt;). Why is this required to be done? Why don't they simply keep the luggage in the luggage compartment? Why is loading the luggage piece-by-piece time consuming, and at the end, in second photo mentioned there, the luggage is being loaded piece-by-piece. What is that? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-02-11T12:00:36.787" Title="Why is luggage required to be loaded in containers?" Tags="&lt;airliner&gt;&lt;baggage-handling-system&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17613" PostTypeId="2" ParentId="17612" CreationDate="2015-08-06T07:17:28.283" Score="7" Body="&lt;p&gt;Well there are several advantages of loading the luggage in unit load devices (ULDs) such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In ULD, the luggage suffers much less shock than it would, if left alone. Else, the incidence of baggage manhandling would increase several times. We are already losing &lt;a href=&quot;http://ags-airlinegroundservices.com/previous-issues/airline-ground-services-june-2013/containers-can-take-the-strain&quot; rel=&quot;nofollow&quot;&gt;\$2.58 bn/year&lt;/a&gt;  due to this.&lt;/li&gt;&#xA;&lt;li&gt;ULDs lead to better use of aircraft cargo space. Stacking the luggage one over the other would be a very time consuming and tiring job, and if it is not done, then a lot of cargo space of aircraft would be wasted. ULDs help prevent this.&lt;/li&gt;&#xA;&lt;li&gt;ULDs are cost effective. Compare the cost of 100s people busy in stacking the luggage, and one conveyor belt doing the job.&lt;/li&gt;&#xA;&lt;li&gt;ULDs are safer, in the way they prevent unauthorized access to the luggage.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And, in the second picture shown there, the luggage is being loaded into luggage hold. Which has several Pallets/Nets for storing small ammount of luggage. Usually, they are used to store some small cargo belonging to first class passengers.&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-06T15:01:13.980" LastActivityDate="2015-08-06T15:01:13.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17614" PostTypeId="2" ParentId="17605" CreationDate="2015-08-06T07:32:29.760" Score="5" Body="&lt;p&gt;A commercial jet, designed to carry people, like the '747 or any other jetliner, need to fullfill a series of requirement about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;noise (both inside and outside)&lt;/li&gt;&#xA;&lt;li&gt;safety (emergency exits, oxygen masks and other safety devices)&lt;/li&gt;&#xA;&lt;li&gt;dimensions (space between gates at airport are a design contraint)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, the areas around windows and doors require reinforcement in the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All those things are unnecessary on a military transport. Other features are usually required like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;operating from unpaved runway (need special landing gears)&lt;/li&gt;&#xA;&lt;li&gt;mid-air refueling (too dangerous for a jetliner)&lt;/li&gt;&#xA;&lt;li&gt;being able to drop cargo mid-air (requires a ramp on the tail of the aircraft)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A lot of considerations can be done, but converting or modifying aircrafts isn't an easy thing.&#xA;One big exception are tankers. There's only one &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/the-worlds-only-kc-747-tanker-is-flown-by-the-iranian-a-1581314071&quot; rel=&quot;noreferrer&quot;&gt;KC-747 Tanker&lt;/a&gt; and is flown by the Iranian Air Force.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-08-06T07:32:29.760" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17615" PostTypeId="2" ParentId="17610" CreationDate="2015-08-06T08:18:20.680" Score="9" Body="&lt;p&gt;In this answer I'll assume you are analysing ADS-B data on 1090 MHz, which is the defacto global standard. I am less familiar with the ADS-B on UAT (987 MHz) which is used in addition to 1090MHz in the USA, but I assume the same logic applies. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no ICAO addresses assigned to TIS-B targets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft has an ICAO-address which is detected by the surveillance sensors (e.g. Mode S radar, multilateration system) and the aircraft is not transmitting ADS-B, then a TIS-B target will be created with the ICAO 24 bit address. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft has no ICAO-address, (i.e. it has a Mode A/C transponder / ATCRBS) and is not transmitting ADS-B, then a TIS-B target will be created with a 24 bit address that consists of the Mode A code (first 12 bits) and a unique surveillance system track number (last 12 bits). Primary radar targets are allocated a &quot;Mode A code&quot; of all zeros.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To determine whether you receive an ADS-B message or a TIS-B message you should start looking at the Downlink Format (DF, first 5 bits of the message) if the DF = 17, then it is an ADS-B message. If the DF = 18 then you look at the control field (CF, bits 6-8). CF = 0 and CF = 1 are ADS-B messages. CF = 2,3 &amp;amp; 5 are TIS-B messages. CF = 6 are ADS-R messages. CF = 4 are TIS-B / ADS-R system status messages. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TIS-B messages contain an ICAO/Mode A Flag (IMF) bit which indicates how to interpret the 24 bit address. The location of this bits varies by message type (e.g. position, velocity) and replaces a bit in the ADS-B format that has no meaning in TIS-B.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-08-06T13:38:31.627" LastActivityDate="2015-08-06T13:38:31.627" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17616" PostTypeId="2" ParentId="17605" CreationDate="2015-08-06T08:26:50.493" Score="24" Body="&lt;p&gt;C-5 Galaxy was designed to military requirements that for cargo aircraft include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;operating from unpaved runways (I am not sure in case of C-5, but probably yes)&lt;/li&gt;&#xA;&lt;li&gt;operating from airfields without much support&lt;/li&gt;&#xA;&lt;li&gt;operating from short runways&lt;/li&gt;&#xA;&lt;li&gt;paradrop capability&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These basically imply a high-wing design so that engines are high (to minimize risk of foreign object damage) and the deck is lower for easier loading, front and rear cargo door with loading ramps so loading is possible without any ground infrastructure and some excess thrust for sufficient performance on short fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However that design is &lt;em&gt;less efficient&lt;/em&gt;. It has higher operating cost. The air force is willing to pay it, because it needs the capabilities it requested. But commercial operations don't need those things, because it has enough well equipped airports to operate from. So the higher cost of operating an L-500 (as civil version of C-5 would be called) makes it uninteresting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-747 only shares one design feature with C-5, the raised cockpit that allows full-height (well, almost) cargo door in the nose, but otherwise it is optimized to minimize operating cost, making it great cargo plane for operations between airports.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On a side note, there is &lt;em&gt;some&lt;/em&gt; commercial demand for transporting heavy or large cargo to less equipped airports. These are currently covered by ex-soviet-military An-124 aircraft that look very similar to Galaxy, are a bit larger, are certainly able to land on unpaved runways and were simply available when Soviet Union collapsed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2018-05-11T07:27:13.187" LastActivityDate="2018-05-11T07:27:13.187" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="17617" PostTypeId="2" ParentId="17612" CreationDate="2015-08-06T09:15:43.677" Score="22" Body="&lt;p&gt;The central cargo hold is usually pretty big and open, if cargo was placed in loosely then it might shift in flight which can cause the center of mass to shift or damage the walls of the hold. Putting them in containers and fixing those down will prevent that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The containers can also be weighed before hand and their position set to ensure the center of mass ends up where it should be. With loose cargo the pilot would need to rely on the intuition and experience of the loaders to ensure that they don't put all the heavy stuff on one side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Loading loose luggage requires that the loader in the cargo hold handles each bag while stacking them. The hold also needs to be full enough that the luggage can't shift around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The smaller forward and rear cargo holds (or on smaller planes) can still accommodate loose luggage (or more precisely they are too small for the containers to fit). They will also have netting to provide barriers against shifting.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-08-06T09:15:43.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17618" PostTypeId="2" ParentId="17612" CreationDate="2015-08-06T09:42:23.027" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why is this required to be done?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as I know, this is not required by law, it is an operational practice by airlines. According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot;&gt;Wikipedia&lt;/a&gt; &lt;em&gt;&quot;It allows a large quantity of cargo to be bundled into a single unit. Since this leads to fewer units to load, it saves ground crews time and effort and helps prevent delayed flights.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why don't they simply keep the luggage in the luggage compartment?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;baggage can be loaded into ULDs while the aircraft they are intended for is still in flight. This reduces turn-around time. Aircraft only earn money when they are in the air, on the ground they bleed money from the airline's shareholders. Airlines try to keep aircraft in the air and avoid having them on the ground as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why is loading the luggage piece-by-piece time consuming&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because luggage is not of uniform size, shape and strength. Therefore it is a labour-intensive process not especially amenable to full mechanisation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It simply takes longer to load 50 (say) randomly shaped objects than it does to load one object of standardised shape and size.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;at the end, in second photo mentioned there, the luggage is being loaded piece-by-piece. What is that?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't know, but it seems plausible that some passengers are willing to pay for their luggage to be carefully hand loaded. I.e. first-class. This allows those passengers to pay for an express boarding process and spend less time in the airport.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-08-06T09:42:23.027" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17619" PostTypeId="2" ParentId="15775" CreationDate="2015-08-06T09:55:55.610" Score="0" Body="&lt;p&gt;Its difficult to see how this feature could ever work, because you move the stick to move the wings, and then centralise it again to stop the roll. I am sure though it would never be quite central, small adjustments would have to be made all the time to make the flight path accurate and the aircraft might be overbanking or under banking depending on its attitude for example. So its truly pilot skill you are seeing when you watch the Blues and long may it continue this way!&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-06T09:55:55.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17620" PostTypeId="2" ParentId="17605" CreationDate="2015-08-06T10:17:44.013" Score="3" Body="&lt;p&gt;I doubt any commercial operator would &lt;em&gt;want&lt;/em&gt; to use a C-5. The 747-400 series is roughly contemporary with the C-5B. Compared to the 747-400F freighter, the C-5B:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;is slower (cruise speed of Mach 0.79 vs Mach 0.85);&lt;/li&gt;&#xA;&lt;li&gt;has a smaller internal diameter (19ft vs 20ft) and isn't much longer (247ft vs 231ft externally);&lt;/li&gt;&#xA;&lt;li&gt;has a cripplingly short range when fully loaded (2,760mi without refuelling isn't even enough to get you from London to Moncton, let alone London to New York, vs over 5,000mi);&lt;/li&gt;&#xA;&lt;li&gt;carries less (122t maximum payload, vs 128t for the 747-400F)&lt;/li&gt;&#xA;&lt;li&gt;requires a cockpit crew of four, vs two;&lt;/li&gt;&#xA;&lt;li&gt;uses huge amounts of fuel (the 747 gets twice times the range from fuel tanks that are only 10% larger).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main benefits of the C-5 are that its high wings and low landing gear make it easier to load: you don't have to lift everything fifteen feet in the air to get it into the plane. and I think the C-5's cargo bay is full-height for its whole length, whereas the 747 has reduced height at the front under the cockpit. That also makes loading a 747 something of a sliding-blocks puzzle, since any full-height load has to go in through the side door and be turned, which limits the length of any item; the C-5 has a tail ramp that lets you load an object of almost any length that will physically fit. The C-5 can also use lower quality, shorter runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines, even cargo airlines, don't carry many long, tall, heavy loads, and they fly to and from well-maintained airports with nice runways, so don't need the advantages the C-5 gives.  That just leaves the disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Sources: &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot; rel=&quot;nofollow&quot;&gt;C-5 on Wikipedia&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow&quot;&gt;747 on Wikipedia&lt;/a&gt;, &lt;a href=&quot;http://www.boeing.com/resources/boeingdotcom/company/about_bca/startup/pdf/freighters/747-400f.pdf&quot; rel=&quot;nofollow&quot;&gt;Boeing 747-400F factsheet&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-08-06T10:17:44.013" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17621" PostTypeId="1" AcceptedAnswerId="20757" CreationDate="2015-08-06T10:57:07.583" Score="13" ViewCount="1791" Body="&lt;p&gt;I'm idly curious to know what type of physical storage medium (e.g. is it a &quot;mini-CD&quot;, USB key, a little hard drive, maybe a tape) is used for delivering avionics updates, for an as-recent-as-possible aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For big (e.g. commercial airliner) and/or military?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess you're not downloading updates from the internet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could you (optionally) also paint a vague &lt;strong&gt;public-domain&lt;/strong&gt; picture of how the &quot;chain of trust&quot; works? Or is the delivery route (media passing hand to hand) not especially secure, and instead all the chain of trust is in built-in digital signatures?&lt;/p&gt;&#xA;" OwnerUserId="556" LastEditorUserId="167" LastEditDate="2015-09-08T00:51:24.220" LastActivityDate="2016-08-19T16:26:05.610" Title="How are avionics updates delivered?" Tags="&lt;avionics&gt;&lt;security&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17622" PostTypeId="1" AcceptedAnswerId="17624" CreationDate="2015-08-06T12:56:05.770" Score="16" ViewCount="7148" Body="&lt;ul&gt;&#xA;&lt;li&gt;Do airline pilots eat while flying or do they wait until they are back on the ground?&lt;/li&gt;&#xA;&lt;li&gt;If they do eat, do they get the same food that is served to the passengers or do they bring their own meal?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9690" LastEditorUserId="12720" LastEditDate="2016-02-10T13:25:30.240" LastActivityDate="2019-05-16T00:41:06.070" Title="What do airline pilots eat on a flight, and when?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;&lt;crew&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17623" PostTypeId="1" AcceptedAnswerId="17645" CreationDate="2015-08-06T13:29:26.183" Score="12" ViewCount="4052" Body="&lt;p&gt;This is &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;noreferrer&quot;&gt;the Beluga&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/doFo4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/doFo4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's used for carrying pieces of a fuselage (of much larger planes) from one place to another so they can be fitted together to make a plane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I recall, it's based on an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A300&quot; rel=&quot;noreferrer&quot;&gt;Airbus A300&lt;/a&gt;, and then they added on the huge bulging fuselage piece so it could carry more stuff and moved the cockpit down a bit to make way for the huge door at the front of the bulge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is what did they do in terms of wing/control surface design to keep the plane from becoming unstable.  Clearly when this plane is fully loaded the CG is much much higher than a regular A300.  Which seems like it would make it more likely to want to tip over in some fashion. What did they do to counter-act this?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="946" LastEditDate="2015-08-06T21:55:51.257" LastActivityDate="2019-01-02T12:24:21.573" Title="How do the Airbus Beluga's wing/control surfaces deal with its high center of gravity?" Tags="&lt;flight-controls&gt;&lt;stability&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17624" PostTypeId="2" ParentId="17622" CreationDate="2015-08-06T13:30:24.303" Score="16" Body="&lt;p&gt;&lt;strong&gt;1:&lt;/strong&gt; Do pilots eat during flight or they wait until they are back on the ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As pilots happen to be humans, their metabolism works in a similar fashion as yours or mine work. So they eat when they are hungry. On a long flight, they can eat during the flight, but on short flights (e.g. 30 minutes - 2 hours), they might not get enough free time to have a meal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On busy days, pilots may not get enough time to have proper meals, so they try to eat small meals containing more nutrition. This is detailed in an article on &lt;a href=&quot;http://www.airlinepilotcentral.com/articles/professional-articles/meals-on-the-run-101.html&quot; rel=&quot;noreferrer&quot;&gt;Airline Pilot Central&lt;/a&gt;. They also avoid heavy meals before a flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2:&lt;/strong&gt; Do they get the same food that is served to the passengers or do they bring their own meal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the time, food served to the passengers is the same which is served to the pilots, although they don't &lt;a href=&quot;https://aviation.stackexchange.com/q/555/65&quot;&gt;eat the exact same food&lt;/a&gt;. An airline &lt;a href=&quot;http://travel.cnn.com/seoul/visit/interview-with-a-pilot-975762&quot; rel=&quot;noreferrer&quot;&gt;pilot revealed&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the pilot gets the first class meal and the copilot the business&#xA;  class meal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="65" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-08-06T13:30:24.303" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17625" PostTypeId="2" ParentId="17623" CreationDate="2015-08-06T13:44:44.453" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8cwPp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8cwPp.jpg&quot; alt=&quot;Aircraft Stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As we can see in the above picture, an aircraft's center of gravity (CG) always lies at the intersection point of the three axes. So whenever CG is shifted along one axis, it affects the other two also.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When CG is shifted vertically (along vertical axis), it affects directional stability. In such case, rudder is needed to ensure directional stability.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The unusual bulge in the fuselage of an Airbus Beluga may make one think it can carry more weight than the A330, but that is not correct. &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;MTOW&lt;/a&gt; of A330 is between &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A300#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;364,000-378,500 lbs&lt;/a&gt;, however &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_Beluga#Specifications_.28A300-600ST.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beluga's MTOW&lt;/a&gt; is 341,713 lbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since CG does get shifted upwards in Beluga, it affects the aircraft's directional stability. It has been mentioned at several places (&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; and &lt;a href=&quot;http://www.diseno-art.com/encyclopedia/archive/beluga_transport.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://avitechreader.blogspot.com/2012/09/the-airbus-beluga.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;) that the tail of Airbus Beluga has been enlarged and strengthened to maintain &lt;a href=&quot;https://en.wikipedia.org/wiki/Directional_stability&quot; rel=&quot;nofollow noreferrer&quot;&gt;directional stability&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xxr7Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xxr7Z.jpg&quot; alt=&quot;Beluga Tail&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;http://i2.cdn.turner.com/cnnnext/dam/assets/140917111005-6-beluga-birthday-airbus-horizontal-large-gallery.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2019-01-02T12:24:21.573" LastActivityDate="2019-01-02T12:24:21.573" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="17627" PostTypeId="1" AcceptedAnswerId="17635" CreationDate="2015-08-06T13:52:37.663" Score="6" ViewCount="1096" Body="&lt;p&gt;After reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/819/why-would-an-airplane-be-approved-for-ditching&quot;&gt;this question&lt;/a&gt; and these &lt;a href=&quot;https://aviation.stackexchange.com/questions/17061/what-is-the-probability-that-passengers-can-survive-a-ditching-in-a-747-at-mtow/17075#17075&quot;&gt;two&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/9925/has-a-commercial-airliner-ever-crash-landed-in-an-ocean/9937#9937&quot;&gt;answers&lt;/a&gt; it is clear that ditching is taken into account, at least for biggest airliners (and with reasons as it occured several times in aviation history).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots are trained to face many technical problems that may lead to an accident (engine flame-out, cabin fire, partial loss of hydraulic power, partial loss of flight computers,...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, many airlines pilots do not posses the qualification (nor the training) to pilot specific categories of aircraft such as fighters, gliders or seaplanes. Thus it makes sense to assume they are not trained to fly in formation or land on water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is an airliners' pilot trained to ditch as he is trained to deal with technical emergencies? If not, what is its knowledge of such situation (only theorical, practice once on simulator,...)? Is there differences between country's regulation? &lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-06T20:42:50.923" Title="Are airliners' pilots trained to safely ditch an aircraft?" Tags="&lt;airliner&gt;&lt;flight-training&gt;&lt;ditching&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17628" PostTypeId="1" AcceptedAnswerId="17630" CreationDate="2015-08-06T13:59:01.037" Score="9" ViewCount="720" Body="&lt;p&gt;&lt;a href=&quot;http://www.heathrowhub.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heathrow Hub&lt;/a&gt; is an independent proposal to expand capacity at Heathrow Airport by extending both of the existing runways up to a total length of about 7,000 metres and dividing them into four so that they each provide two &lt;em&gt;pair of &lt;strong&gt;full length, in-line runways&lt;/strong&gt;, allowing simultaneous take-offs and landings&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zUgCR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zUgCR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How to ensure the planes landing and take-off in the same runways safety?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How many flight can be handled by such design, and how efficiency it is compared to two runways using segregated parallel operations (one for landing and another for takeoff)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="19" LastEditDate="2016-07-08T09:28:31.760" LastActivityDate="2016-07-08T09:28:31.760" Title="What are the safety concerns and efficiency benefits of two in-line runways?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17629" PostTypeId="2" ParentId="17612" CreationDate="2015-08-06T14:25:16.193" Score="4" Body="&lt;p&gt;Think about the benefits of containerisation.  Ships could take days to unload if they carried many different items like lumber, sacks of corn etc.  Along came containers and now you can unload a ship in hours.  The labour intensive part of loading/stacking is distributed toward the containers themselves, and thus frees up the expensive capital item such as a ship or plane to be turned around more quickly.  It all makes economic sense.  so is it required?  yes, if you wish to stay competitive and in business it is. &lt;/p&gt;&#xA;" OwnerUserId="9710" LastActivityDate="2015-08-06T14:25:16.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17630" PostTypeId="2" ParentId="17628" CreationDate="2015-08-06T15:42:41.203" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How to ensure the planes landing and take-off in the same runways safety?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No one knows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note this isn't exactly what is being &lt;a href=&quot;http://www.heathrowhub.com/our-purposal/our-proposal.aspx&quot; rel=&quot;nofollow&quot;&gt;proposed&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By dividing it in two with a generous central buffer zone, we create two in-line runways, allowing aircraft to simultaneously land on one and take off on the other.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So that isn't simultaneous landing and taking off on the same runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently only one LHR runway is used for take-offs at any time. The runway is switched to provide respite from noise to local residents in the take-off path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the surrounding airspace isn't set up in a way that would allow separation for concurrent take-off from two runways. A major reorganisation would be needed of airspace in that region of the UK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that currently, simultaneous take-off require parallel runways a mile or more apart.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How many flight can be handled by such design&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No one knows. Maybe a c 46% increase from 480,000 to 700,000 air transport movements a year. See reference below. Bear in mind that Heathrow is subject to a night-time curfew.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How efficient is it compared to parallel runways?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No one knows.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/371857/14-operational-efficiency--ground-lhr-enr.pdf&quot; rel=&quot;nofollow&quot;&gt;airports commission&lt;/a&gt; in 2014:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The concept of an in-line runway is unconventional, has never been used elsewhare and is not envisaged in international, EU or national regulatory instruments, standards or recommendations for safe design or operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-06T16:00:59.647" LastActivityDate="2015-08-06T16:00:59.647" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17632" PostTypeId="2" ParentId="17246" CreationDate="2015-08-06T17:56:10.683" Score="7" Body="&lt;p&gt;The way they coordinate them is actually extremely simple.  The show at a ball game (or any major event) is usually very heavily choreographed, so they know exactly when it's going to end (seriously, often down to the exact second.  They practice the heck out of those things.)  So, step number one, the organizers tell the Military the exact time for the flyover in the show.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the militaries part, well, it's important to remember that military aviation involves a lot of instances where you have to be over a target, dropping a munition, at an extremely precise time (again, down to the second).  Otherwise you may screw up the timing of the whole operation, or the target may be gone, or the defenses may be up (etc etc).  It's really important to be precise in the military.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The procedure itself is still fairly conventional though.  You figure out what time you need to be there, then you figure out how much time it will take you to get there.  Subtract the latter from the former and boom, you have the time you need to take off.  Then all they need is a few check points to make sure they are on schedule, approaching at the proper speed.  And they adjust as needs be.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, keep an eye on the clock, slow down if you're ahead of schedule, speed up if you're behind.  To increase accuracy, you may build in a holding spot near the event, that way if you're 20 minutes early (of if the planning goes out the window for the show and they're late...), you can hold there and pick the approach up again when the time is right.  It's still all about watching the speed and the clock though.  With a lot of practice, you end up hitting your waypoints, hold points and destination, with (literal) military precision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know more details though, check out this article from ESPN: &lt;a href=&quot;http://espn.go.com/blog/playbook/fandom/post/_/id/6544/how-flyovers-hit-their-exact-marks-at-games&quot; rel=&quot;nofollow&quot;&gt;How Flyovers Hit Their Exact Marks at Games&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a final thought, I think you may need to adjust your thought experiment.  Military aircraft can get clearance through just about any airspace prior to the actual mission.  Plus, they can approach from any direction, so it's pretty easy to find a lane that has &lt;em&gt;no traffic&lt;/em&gt;.  So in your car thought experiment, there should have been no traffic and a straight shot to the overpass.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plus, there should have been regular beacons (like GPS or NDB fixes) to tell you how far you are from that overpass.  And the person driving the car would have known exactly what time they needed to pass each beacon in order to get to the overpass in time.  Then, with a heck of a lot of practice, I'm sure that driver could go under that underpass at the exact right moment pretty much every single time...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="43" LastEditDate="2015-08-06T19:52:24.720" LastActivityDate="2015-08-06T19:52:24.720" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17634" PostTypeId="1" CreationDate="2015-08-06T18:21:34.273" Score="10" ViewCount="2345" Body="&lt;p&gt;Why are the lower deck areas shaped like that, does that save some space? I find it common across lot of big aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pic of a 777:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/wsCOx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wsCOx.jpg&quot; alt=&quot;777 Cargo Compartment&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-08-06T20:29:12.307" LastActivityDate="2015-08-06T20:29:12.307" Title="Why is the shape of the cargo compartment similar in large aircraft?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17635" PostTypeId="2" ParentId="17627" CreationDate="2015-08-06T18:27:15.413" Score="10" Body="&lt;p&gt;This is a very dated answer now, but for what it's worth, prior to my retirement in 1999 from a U.S. airline, we did ditching scenarios in 747-100/200 sims during initial training and then occasionally during recurrent training. Proper execution included being on-speed for your weight, nose attitude at touchdown (5 degrees up as I remember), aircraft configuration (gear up but I don't remember the flap setting), determination of wave direction if possible, and landing parallel to the wave action. It was a relatively easy scenario for the pilots but a busy scenario for the flight engineer. He had to position valves properly at the right time, including making sure the pressurization outflow valves were closed to prevent fuselage flooding.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-08-06T18:27:15.413" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17636" PostTypeId="2" ParentId="17634" CreationDate="2015-08-06T18:32:58.773" Score="19" Body="&lt;p&gt;The answer lies in the existence of something called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;Unit Load Device (ULD)&lt;/a&gt; -- basically a cargo pod for aircraft that's the equivalent of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pallet&quot; rel=&quot;nofollow noreferrer&quot;&gt;shipping pallet&lt;/a&gt;.&lt;br&gt;&#xA;ULDs allow oddly-shaped cargo (bags, assorted-size boxes, etc.) to be loaded efficiently in a standard volume and easily secured for flight (using hold-down lugs in the floor).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shape of the cargo deck is designed to pack in as many ULDs as possible:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/jTC4R.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jTC4R.jpg&quot; alt=&quot;A300 cross-section with ULDs&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;and as you can see from the cross-section the sloping sides on the bottom are a concession to the circular cross-section of the fuselage/pressure vessel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some other advantages of ULDs as they pertain to airline operations and baggage loading are described &lt;a href=&quot;https://aviation.stackexchange.com/questions/17612/why-is-luggage-required-to-be-loaded-in-containers&quot;&gt;over on this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-08-06T18:32:58.773" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="17637" PostTypeId="2" ParentId="17612" CreationDate="2015-08-06T18:39:20.103" Score="3" Body="&lt;p&gt;There are some &lt;strong&gt;safety and security aspects&lt;/strong&gt; to containing luggage within containers. When content leaks, goes bad, or &lt;a href=&quot;http://www.aeronautics.nasa.gov/docs/chicago/ah.htm&quot; rel=&quot;nofollow&quot;&gt;even explodes&lt;/a&gt;, the container may serve to limit the damage to other luggage within the aircraft, along with the aircraft itself.&lt;/p&gt;&#xA;" OwnerUserId="995" LastActivityDate="2015-08-06T18:39:20.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17638" PostTypeId="1" CreationDate="2015-08-06T18:51:38.747" Score="3" ViewCount="249" Body="&lt;p&gt;Modern aircraft cruise with the center of gravity close to the most rearward position to minimise trim drag, usually achieved with fuel in the tail surfaces. This is transferred forward before or during descent for landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it feasible that unexpected nose-up inputs could lead to partial stall with the aerodynamic center moving rearward, aggravating the nose high attitude to cause mushing? This is my suggestion that might explain the loss of AF447.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without ASI (pitot icing) a pilot without experience of this might not recognise the problem. Further, in that attitude elevators could be ineffective and fuel transfer too slow for recovery that way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was a serious problem with T-tails and caused accidents to DC9, Trident, BAC1-11 and Tomahawk aircraft; maybe others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only solutions were stall warning and stick pusher systems, apart from streaming the braking 'chute by an RAF Victor crew.&lt;/p&gt;&#xA;" OwnerUserId="9683" LastEditorUserId="3201" LastEditDate="2016-01-30T21:43:57.747" LastActivityDate="2016-01-30T21:43:57.747" Title="Could a rear center of gravity position cause an airliner to lose control when a pitch-up is commanded?" Tags="&lt;safety&gt;&lt;af447-accident&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-08-06T20:44:20.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="17639" PostTypeId="2" ParentId="8556" CreationDate="2015-08-06T20:03:46.620" Score="-2" Body="&lt;p&gt;Yes because a winglet reduces the drag caused by the lower part of the wing comes onto the higher part of the wing and rotates forming a vortex called wing tip vortex and the winglet reduces the strength of the vortex reduces the drag also makes it more efficient and has extra range from the winglet. So its better to have a winglet than no winglet&lt;/p&gt;&#xA;" OwnerUserId="9715" LastActivityDate="2015-08-06T20:03:46.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17640" PostTypeId="2" ParentId="2111" CreationDate="2015-08-06T20:06:09.420" Score="0" Body="&lt;p&gt;Basically what happens with an airplane without a wingtip is the high pressure area comes over the lower pressure area and creates a giant vortex called a wing tip vortex and the winglet reduces the strength of the vortex reduces drag, increasing lift, and increasing the aircrafts range.&lt;/p&gt;&#xA;" OwnerUserId="9715" LastActivityDate="2015-08-06T20:06:09.420" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17641" PostTypeId="1" CreationDate="2015-08-06T20:19:29.243" Score="2" ViewCount="4263" Body="&lt;p&gt;I know a lot about airplanes, but I've always wondered the vents deal with air pressure in the sky&lt;/p&gt;&#xA;" OwnerUserId="9715" LastActivityDate="2019-04-07T13:10:09.687" Title="How does air conditioning work on a commercial airliner?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-08-06T20:44:45.557" ContentLicense="CC BY-SA 3.0" />
  <row Id="17642" PostTypeId="2" ParentId="17641" CreationDate="2015-08-06T20:26:38.323" Score="5" Body="&lt;p&gt;Came across this diagram that sums it up pretty nicely:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://mikestengel.files.wordpress.com/2012/07/av-air-system-bleed-air2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://mikestengel.files.wordpress.com/2012/07/av-air-system-bleed-air2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You get 'bleed' air from the engine compressor stage. On 'bleedless' aircraft, such as the B787, this is done by electric compressors instead.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air temperature and pressure is adjusted as necessary in the conditioning packs since it heated up a lot when it was compressed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air is then distributed to the different 'zones'. A bit of the cabin air is recirculated. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some areas, such as the cockpit, generally receive air directly from the packs without recirculating at a slightly higher pressure, to blow possible smoke away from the interior and to prevent smoke being recirculated into the cockpit. For the same reason, you try create a flow out through the baggage hold.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here is a more complicated diagram from avsoft's website for a CRJ200:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jiw8w.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jiw8w.jpg&quot; alt=&quot;crj200&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-04-07T13:10:09.687" LastActivityDate="2019-04-07T13:10:09.687" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="17643" PostTypeId="2" ParentId="17627" CreationDate="2015-08-06T20:42:50.923" Score="2" Body="&lt;p&gt;There is underwater pilot survival training, but its mostly for small planes and for helis:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.proaviation.ca/Egress.html&quot; rel=&quot;nofollow&quot;&gt;http://www.proaviation.ca/Egress.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-06T20:42:50.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17644" PostTypeId="2" ParentId="17638" CreationDate="2015-08-06T21:44:28.060" Score="3" Body="&lt;p&gt;On virtually any swept-wing design, &quot;wingtip stalls&quot; are a danger. Most light aircraft are designed with a straight wing and a leading-edge contour such that the inside of the wing stalls first. This has two advantages for light craft; first, aileron control is available as long as possible into stall entry, allowing roll control and thus the ability to stay coordinated. Second, the departure of airflow over the top inside of the wing will reduce or eliminate the downwash of air over the horizontal stabilizer, which normally corrects for a slight nose-heavy CG. With the balancing force gone, the normal response of the aircraft will be to nose down, restoring a lower AOA and building forward airspeed to let the pilot recover quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a swept wing as is seen on modern jet airliners, the wingtips tend to stall first instead, because the airflow over the swept wing lowers the stagnation point and thus the effective angle of attack of rearward sections of the wing, so the wingtips at the rear will exceed the critical AOA first. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the wingtip stalls first on a swept wing, two things happen. First, aileron control is severely affected, making it harder to stay wings-level and avoid entering a slip or even a spin. Second, the center of lift from the unstalled portion of the wing moves forward, placing the CG further behind it. An aft CG works against pilot efforts to nose the aircraft back down to recover, and in an uncoordinated stall the aft CG will keep the tail of the airplane &quot;outwards&quot; from the center of the spin, hindering or preventing efforts to cancel out the rotation with the rudder as the vertical stabilizer will be stalled due to the extreme &quot;sideslip&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a potential problem in any airliner, where the weight is distributed along the majority of the fuselage. Any significant deviation from mean values for per-passenger or per-bag weights can place the CG too far aft. Tail trim tanks can further exacerbate this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Air France 447's crash, in my amateur analysis, was not caused by trim characteristics. It was primarily caused by the pitot tube icing. This had several detrimental effects on the flight crew's situational awareness:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The disagreement of the plane's two pitot-static systems cause the flight director to unexpectedly disengage the autopilot, setting the flight crew on their heels.&lt;/li&gt;&#xA;&lt;li&gt;This same disagreement in the pitot-static data also caused the flight director to switch from &quot;normal law&quot; to &quot;alternate law 2&quot; which among other things disabled roll and pitch/AOA limiters, as the data used to calculate those limits is no longer reliable.&lt;/li&gt;&#xA;&lt;li&gt;Lastly, the lack of reliable pitot-static data was reflected in cockpit instrument displays. We don't know exactly what they saw because information on the status of the right side pitot system is unavailable (it was not recorded by the black boxes). However, we do know the disagreement of data caused the red-flagging of practically all information reliant on such data, including the airspeed and altimeter tapes, the flight director, velocity vector, and all secondary indicators including AOA readouts, the stall horn, etc. The flight crew would have been totally reliant on external visible references to determine the aircraft was stalled.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A secondary instrumental cause was the stall indicator system itself. Counter-intuitively, the stall warning was issued when the aircraft was nosed down, and stopped when the aircraft nosed up. This was due to the flight computer treating the extreme AOA calculations (in excess of 40 degrees) as unreliable. Nosing down brought the AOA back into the &quot;reliable&quot; band, but the resulting alarms were counter-intuitive to the pilots; applying a control input and hearing an audible warning is usually a signal to back off that control input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the flight crew themselves demonstrated a lack of familiarity with the behavior of the aircraft in exceptional circumstances; the loss of pitch/roll limiters and the counter-intuitive stall horn behavior caused the flight crew, in the absence of the captain, to make a series of critical and ultimately fatal overcorrections and inactions.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-10T23:14:35.073" LastActivityDate="2015-08-10T23:14:35.073" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17645" PostTypeId="2" ParentId="17623" CreationDate="2015-08-06T22:12:48.887" Score="8" Body="&lt;p&gt;As long as the aircraft flies without much sideslip, the vertical position of the center of gravity is not important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a common misconception that the aircraft could &quot;tip over&quot; when banking due to a high location of the center of gravity, or even that dihedral would right the aircraft up because the lower wing will create more lift. &lt;strong&gt;This is all wrong!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To understand why, look where gravity is pointing in banking flight. By gravity I mean the total acceleration felt by the pilots and passengers, the apparent vertical direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5GYr7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5GYr7.png&quot; alt=&quot;A320 front view straight and banked with force vectors&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A320 front view straight and banked with force vectors in the aircraft's frame of reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The force vectors in banked flight don't differ from those in level flight, only their magnitude grows. In both cases the apparent vertical is parallel to the vertical plane of symmetry and will go straight through the center of gravity, regardless of its vertical location. Therefore, it has no lever arm and produces no momentum around the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put it another way, the aircraft banks in a coordinated turn to keep the apparent vertical in its vertical plane of symmetry, now that a horizontal force needs to be added to change the aircraft's angular momentum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, neither the wing nor the control surfaces need any special adaptation to the huge fuselage. Only the vertical tail needs to be increased to compensate for the increased side area ahead of the center of gravity. In case of the Beluga, two vertical fins were added and the strake enlarged. This is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/3382/why-dont-horizontal-stabilizers-have-winglets/11784#11784&quot;&gt;very common procedure for modifications of existing aircraft&lt;/a&gt;, because it is easier than designing a new vertical and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5239/would-a-vertical-stabilizer-that-extends-both-above-and-below-the-centerline-be/5242#5242&quot;&gt;improves handling compared to a new, scaled-up fin&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NiQVz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NiQVz.png&quot; alt=&quot;Side view of the Airbus Beluga&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side view of the Airbus Beluga (Picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/A300Belugav1.0.png/1024px-A300Belugav1.0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage has its aerodynamic center ahead of the center of gravity, so increasing its size will also increase its destabilizing yawing moment in a sideslip. This requires more stabilizing area at the rear, which can be kept relatively small since its aspect ratio is much higher than that of the fuselage, making it more responsive to sideslip angle changes. Both together will create a side force in sideslip which will be substantially bigger than that of an unmodified A300 in the same conditions. This sideslip-induced side force and the drag which comes with it will make the flying characteristics of the Beluga different to that of an A300. Since it acts quite a bit above the center of gravity, it will add a rolling moment, increasing the dihedral effect. I expect that it will be harder to build up a sideslip angle in the Beluga, and if the pilot crosses controls, the aircraft will slow down more quickly than a regular A300.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When designing the Beluga, it was clear from earlier planes (Super Guppy, 3M-T or BM-T Atlant) that the oversized cargo bay would not make flying impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gN5dH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gN5dH.jpg&quot; alt=&quot;3M-T in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 3M-T/BM-T modification for rocket stage airlifting. Picture &lt;a href=&quot;http://englishrussia.com/2013/06/25/atlant-the-special-transport-aircraft/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-07T18:23:43.923" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17646" PostTypeId="1" AcceptedAnswerId="17678" CreationDate="2015-08-06T22:53:12.193" Score="5" ViewCount="706" Body="&lt;p&gt;Should an IFR-certified radio's automated nav aid identification feature be considered positive identification? Should manual identification still be performed? Does anyone know if this is addressed in any FAA regulation or publication?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of automated identification is found on the Garmin 430. When a nav aid is tuned automated identification takes place and the result is annunciated visually.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-07T16:15:53.330" LastActivityDate="2015-08-07T16:15:53.330" Title="Should an IFR-certified radio's automated nav aid identification feature be considered positive identification?" Tags="&lt;navigation&gt;&lt;avionics&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17647" PostTypeId="1" AcceptedAnswerId="17667" CreationDate="2015-08-06T23:08:25.230" Score="2" ViewCount="746" Body="&lt;p&gt;I saw on wiki that a boeing 737 flys at about 38,000ft and a Concorde flys at 60,000ft. What made it possible, and advantageous, for Concorde to fly so much higher?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="524" LastEditDate="2015-08-07T09:36:15.810" LastActivityDate="2015-08-07T13:20:51.770" Title="Why do supersonic planes fly higher than subsonic airliners?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2015-08-07T09:04:22.810" ContentLicense="CC BY-SA 3.0" />
  <row Id="17648" PostTypeId="1" AcceptedAnswerId="17666" CreationDate="2015-08-06T23:14:47.787" Score="1" ViewCount="13204" Body="&lt;p&gt;I was just curious because the air is very compressed in the engine and some things do run on compressed air. And what if the engine was powered all by electricity?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/az3N4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/az3N4.jpg&quot; alt=&quot;PW geared turbofan cutaway view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-08-07T16:19:44.593" LastActivityDate="2015-08-07T16:41:20.923" Title="Can an engine on a Boeing 737 fly just using compressed air instead of jet fuel?" Tags="&lt;jet-engine&gt;" AnswerCount="5" CommentCount="7" ClosedDate="2015-08-14T14:22:00.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="17649" PostTypeId="2" ParentId="17648" CreationDate="2015-08-06T23:19:02.810" Score="3" Body="&lt;p&gt;No. Air is compressed because we have jetful to run the compressor in the first place.&#xA;No fuel, no compressed air (or very very few, from to drag induced by windmilling the engine).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a look at &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_engine&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Jet_engine&lt;/a&gt; for more informations&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A plane with compressed air tanks would also not be possible, as it requires A LOT of air to move an aircraft &lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="4105" LastEditDate="2015-08-07T10:16:53.560" LastActivityDate="2015-08-07T10:16:53.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17650" PostTypeId="2" ParentId="17647" CreationDate="2015-08-06T23:24:51.650" Score="1" Body="&lt;p&gt;The air is much thinner up that high and therefore there is much less drag/resistance, therefore an airplane won't heat up as much as it would going the same speed at a lower altitude, and it requires much less thrust/fuel as well (economics matter too when you have paying passengers).&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-08-06T23:24:51.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17651" PostTypeId="1" AcceptedAnswerId="17656" CreationDate="2015-08-06T23:29:29.453" Score="3" ViewCount="2990" Body="&lt;p&gt;I looked at a picture of a q400 engine and it showed air being compressed so I was wondering if it has two systems to generate thrust.&lt;a href=&quot;https://i.stack.imgur.com/EPFvV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EPFvV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-07T03:23:57.377" Title="Do turbo prop airliners generate thrust using the propeller and compressed air or just the propeller?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17652" PostTypeId="2" ParentId="17646" CreationDate="2015-08-06T23:37:34.137" Score="1" Body="&lt;p&gt;I've wondered the same thing with the Garmin G1000 glass cockpit as it has the same functionality as the 430 - it processes the audio morse code signal usually filtered using the ID button on a regular NAVCOM to see if the character code is present. It cannot, however, process a non-morse audio identifier such as a recorded voice and you'll have to listen if it doesn't identify and display the NAVAID's 3-letter identifier automatically. Published recommendations for positive navaid identification are in the FAA Pilot's Handbook of Aeronautical Knowledge Chapter 15, page 23 &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2015.pdf&quot; rel=&quot;nofollow&quot;&gt;Link Here&lt;/a&gt;, and I'm certain in some other places as well (probably the FAA AIM). I will certainly be listening to the morse code just to verify - when flying IFR in IMC (instrument meteorological conditions) your life is on the line. If it's a clear VFR day and you know the route and you definitely know where you are and you're using the NAVAID just for reference to keep a straight course, then maybe not, but in any other situation I'd be listening and checking the morse code or voice recording against my sectional/chart.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2015-08-06T23:43:06.367" LastActivityDate="2015-08-06T23:43:06.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17653" PostTypeId="1" AcceptedAnswerId="17668" CreationDate="2015-08-06T23:37:43.060" Score="4" ViewCount="3958" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6jnbs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6jnbs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Piaggo P-180 is one of the fastest private planes out there and uses the push system.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3201" LastEditDate="2015-08-22T10:56:35.497" LastActivityDate="2019-06-14T20:17:16.660" Title="Why don't turboprop planes have push engines that use thrust more effectively?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2015-08-07T18:23:08.280" ContentLicense="CC BY-SA 3.0" />
  <row Id="17654" PostTypeId="2" ParentId="16784" CreationDate="2015-08-06T23:45:05.157" Score="-3" Body="&lt;p&gt;The correct answer is no. A ufo with its circular shape has trouble traveling through the air. It struggles to travel through the air like a city bus, which  gets 2-6mpg. Depending on the amount of thrust this object has depends whether it can lift up into the air. But it would not be efficient because of the amount of fuel it needs to consume to pass through the air, its kind of like a flying city bus not really very aerodynamic and is terrible in efficiency. If this was powered by human technology it would not be efficient considering if its made by humans, if it was made by aliens then maybe it would be efficient, but that information we do not know and probably never find out in our lifetime and we don't even know if aliens exist. You also have to consider the design of this certain ufo. This shape cannot develop lift and runs fully on thrust, which also decreases its efficiency because of gravity pushing down on the flying object. Imagine an airliner without wings and how much efficiency you loose without the wings.&lt;a href=&quot;https://i.stack.imgur.com/olRFf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/olRFf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Wind tunnel test for a circular shape. If a ufo was so efficient it would have been used on our current airliners. Now lets go into problems with a ufo being an airliner.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Its round circular shape would have trouble fitting into modern day terminals&lt;/li&gt;&#xA;&lt;li&gt;Much thrust needed for vertical takeoff and landings&lt;/li&gt;&#xA;&lt;li&gt;Not much room to store fuel&lt;/li&gt;&#xA;&lt;li&gt;It would be very difficult for pilots to fly this object compared to modern day airliners&lt;/li&gt;&#xA;&lt;li&gt;Airports would be redesigned for these objects which costs billions of dollars&lt;/li&gt;&#xA;&lt;li&gt;Only has one engine to push the object instead of generally 2 on an airliner&lt;/li&gt;&#xA;&lt;li&gt;Lots of weight the one engine needs to lift&lt;/li&gt;&#xA;&lt;li&gt;One engine would be very difficult to do maintenance work on&lt;/li&gt;&#xA;&lt;li&gt;The amount of money needed to be invested into this type of airliner &lt;/li&gt;&#xA;&lt;li&gt;No horizontal or vertical stabilizer &lt;/li&gt;&#xA;&lt;li&gt;Cost even more than the Concorde for maintenance&lt;/li&gt;&#xA;&lt;li&gt;The costs to buy one of these would be 5x the price of a regular airliner&lt;/li&gt;&#xA;&lt;li&gt;Amount of gas needed would be more than the Concorde&lt;/li&gt;&#xA;&lt;li&gt;Amount of money needed to invest in this kind of technology, which doesn't even exist yet&lt;/li&gt;&#xA;&lt;li&gt;No airline would want this because of the price&lt;/li&gt;&#xA;&lt;li&gt;The whole ufo would generate lift, but that technology already exists and that's called a blended wing body, which is more of the focus towards future airliner and already has lots of money invested into it, and investing in a ufo would be too much money considering the amount invested blended wing body designs.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So I hope those 16 reasons helped explain why it would not be more efficient  than a modern day airliner and why it can't go into service. So the article was false for efficiency and other reasons.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-09-17T01:59:19.093" LastActivityDate="2015-09-17T01:59:19.093" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17656" PostTypeId="2" ParentId="17651" CreationDate="2015-08-06T23:49:25.390" Score="4" Body="&lt;p&gt;Turboprop engines transfer almost all of the turbine's rotational energy to the propeller, though there is some waste in heat and exhaust gas as in all engines. The exhaust does not form any major amount of thrust unlike in other turbine engines (&quot;jet engines&quot;, like a turbofan or turbojet). Turboprops are more efficient than other &quot;jet engines&quot; at lower altitudes due to the thickness of the air at lower altitudes whereas jets are more efficient at higher altitudes, though turboprop pilots will tell you they fly a jet, being that a turboprop is still a turbine engine, aka a jet. :-)&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-08-06T23:49:25.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17658" PostTypeId="2" ParentId="17653" CreationDate="2015-08-06T23:53:45.790" Score="4" Body="&lt;p&gt;The Piaggio is certainly fast but I'm pretty sure the speed is due to the plane's overall sleek shape, smooth skin, and resultant low drag working together with the high-power turbine engines. I don't think the push prop design is any more efficient, though the Italian style is first class.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-08-06T23:53:45.790" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17661" PostTypeId="1" AcceptedAnswerId="17670" CreationDate="2015-08-07T00:10:58.850" Score="21" ViewCount="11047" Body="&lt;p&gt;The Concorde normally cruised at an altitude of 55-60,000 feet, but wasn't allowed to fly over populated areas due to the noise it produces. Can the sonic boom of an aircraft at 60,000 feet be heard on the ground?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1520" LastEditDate="2017-05-16T21:22:10.080" LastActivityDate="2018-05-21T22:58:19.973" Title="Can a sonic boom produced at 60,000' be heard on the ground?" Tags="&lt;commercial-aviation&gt;&lt;supersonic&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17662" PostTypeId="2" ParentId="17661" CreationDate="2015-08-07T01:40:27.713" Score="7" Body="&lt;p&gt;60000 ft is only ~11 miles. That high up the sound actually travels over much larger an area. The space shuttle re-entered the atmosphere much higher than that and you could hear the booms from it very well when it would fly over.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2017-12-09T02:44:09.073" LastActivityDate="2017-12-09T02:44:09.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17663" PostTypeId="2" ParentId="17651" CreationDate="2015-08-07T03:23:57.377" Score="0" Body="&lt;p&gt;The PT6A provides approximately 10% extra thrust from exhaust gas&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.turbokart.com/about_pt6.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.turbokart.com/about_pt6.htm&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-07T03:23:57.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17664" PostTypeId="2" ParentId="17648" CreationDate="2015-08-07T07:19:04.650" Score="8" Body="&lt;p&gt;Where would you get the compressed air from? Jet engines &quot;contain&quot; compressed air because the engine itself compresses it using the energy from burning fuel. Asking if you could power the engine by that compressed air is like asking if you could power a car engine by the rotation of the gearbox: it's confusing cause and effect.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-08-07T07:19:04.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17666" PostTypeId="2" ParentId="17648" CreationDate="2015-08-07T08:56:23.797" Score="8" Body="&lt;p&gt;A typical modern turbofan engine produces about 85% of its thrust from bypass flow, i.e. &quot;compressed air&quot;, that never goes through the actual jet core. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as others have mentioned, in order to get the compressors spinning and sucking air in to begin with, you still need an energy source of some kind to turn them and, for lack of a better alternative, current designs still rely on jet core flow to turn both sets of turbines and, by extension, their associated compressors.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-08-07T08:56:23.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17667" PostTypeId="2" ParentId="17647" CreationDate="2015-08-07T08:59:43.763" Score="3" Body="&lt;p&gt;It was necessary for Concorde to fly much higher, and not a voluntary decision. A higher cruise altitude increases the demands on the airframe (examples: &lt;a href=&quot;https://aviation.stackexchange.com/questions/10002/why-is-the-combustor-volume-of-a-jet-engine-decided-by-altitude/10014#10014&quot;&gt;Combustor size&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/15779/why-do-airplanes-have-curved-windows/15781#15781&quot;&gt;pressurization&lt;/a&gt;) and is only accepted when it comes with sufficient benefits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane needs a certain wing area for realistic take-off and landing distances. Also, details like the &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_02_09/article_04_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;maximum tire speed&lt;/a&gt; need to be observed, so the wing area must be large enough to create enough lift at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is proportional to the square of airspeed and air density. The faster a plane flies, the lower the density can be to create sufficient lift. By flying more than twice as fast as a Boeing 737, the Concorde could fly at a fourth of the density by this reasoning. Air density (symbolized by the Greek letter $\rho$) halves approximately with every 5500 m of altitude increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the slender wing needed for low supersonic drag is not as efficient as the sub- / transsonic wing of a 737, so a little more density was needed for the Concorde. The 737 is designed for cruise between 8000 m ($\rho$ = 0.526 kg/m³) and 12000 m ($\rho$ = 0.312 kg/m³), and the Concorde flew between 16500 m ($\rho$ = 0.154 kg/m³) and 18000 m ($\rho$ = 0.121 kg/m³).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-07T13:20:51.770" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="17668" PostTypeId="2" ParentId="17653" CreationDate="2015-08-07T09:03:06.807" Score="5" Body="&lt;p&gt;Pusher engines do not generate more thrust; they are basically the same engines, but mounted in a different configuration. As pointed out by @JanHudec in the comments, this configuration can be more efficient since in a traditional puller configuration the air displaced by the propeller washes over the wings and fuselage, thus increasing drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several considerations, such as those set out in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pusher_configuration#Disadvantages&quot; rel=&quot;nofollow noreferrer&quot;&gt;reference&lt;/a&gt; already given by Greg Hewgill in comments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the main reason why propeller pushers are not as used on commercial aircraft is safety. Consider an aircraft taking off. If the pusher engines are placed, as usual, at the rear of the A/C, then the propeller tips are rather close to the ground. Even if the propeller does not actually make contact, any debris present on the runway and lifted by the A/C can conceivably end up within the propeller disk. This would be, naturally, at about the worst phase of flight to lose power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is perhaps less of a concern on drones and small aircraft used in GA. The pilot (and owner) may choose to forego a bit of safety to obtain a more compact aircraft and where the pilot's field of view is not interfered with by the presence of a spinner disk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point that can be considered is the fact that turboprop engines are generally used in commercial aircraft that require shorter take-off and landing distances, to connect to smaller airports that handle jets with difficulty or not at all. In this case, a pusher configuration that requires higher speeds and longer runways would not be appropriate. On the other hand, in a puller configuration some of the prop-wash can be used to generate further lift through the &lt;a href=&quot;https://en.wikipedia.org/wiki/Coand%C4%83_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coandă effect&lt;/a&gt; and decrease take-off distance.&lt;/p&gt;&#xA;" OwnerUserId="8558" LastEditorUserId="1696" LastEditDate="2019-06-14T20:17:16.660" LastActivityDate="2019-06-14T20:17:16.660" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="17669" PostTypeId="2" ParentId="17648" CreationDate="2015-08-07T09:05:25.697" Score="3" Body="&lt;p&gt;In modern aircraft's jet engines (both turbojets and turbofans), compressed air is used:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For starting the engine, spooling it up until the shut-off valve is opened and the fuel starts to enter and burn in the combustion chamber;&lt;/li&gt;&#xA;&lt;li&gt;For running auxiliary systems, like de-icing and pressurizing equipments;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is not true for some newer engines like the General Electric's GEnx that use an electric starter or little jet engines (including APUs) and sometimes turboshafts (turboprops).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation it's common to refers to the systems running/producing compressed air as 'pneumatic' systems or 'bleed-air'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This, for instance, is the part of the overhead panel of a Boeing 737 used to manage pneumatic systems (taken from &lt;a href=&quot;http://www.b737.org.uk/pneumatics.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.b737.org.uk/pneumatics.htm&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j8rwX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j8rwX.jpg&quot; alt=&quot;Boeing 737 pneumatic panel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="9656" LastEditDate="2015-08-07T09:17:58.500" LastActivityDate="2015-08-07T09:17:58.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17670" PostTypeId="2" ParentId="17661" CreationDate="2015-08-07T10:23:31.893" Score="23" Body="&lt;p&gt;Yes, a sonic boom produced at 60,000' can be heard on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, a sonic boom consist in a steep increase of air pressure, followed by a slow, linear decrease below the nominal ambient pressure, and again a steep increase back to the nominal pressure. It is therefore called &lt;em&gt;N-shaped wave&lt;/em&gt; or just &lt;em&gt;N-wave&lt;/em&gt;. Here is a graph with several sonic booms, measures by NASA and found on &lt;a href=&quot;https://en.wikipedia.org/wiki/Sonic_boom&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CAjsc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CAjsc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same wiki page cites a &lt;a href=&quot;http://www.nasa.gov/centers/dryden/news/FactSheets/FS-016-DFRC.html#.VcRr0DKpBhE&quot; rel=&quot;noreferrer&quot;&gt;document from NASA&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Aircraft        speed   altitude        pressure&#xA;               [mach]   [ft (m)]        [lb/ft² (Pa)]&#xA;&#xA;SR-71           3      80,000 (24,000)  0.9  (43)&#xA;Concorde SST    2      52,000 (16,000)  1.94 (93)&#xA;F-104           1.93   48,000 (15,000)  0.8  (38)&#xA;Space Shuttle   1.5    60,000 (18,000)  1.25 (60)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;These measurements are from aircraft with different altitude. As sound pressure depends from distance like  $p\sim\frac{1}{r}$, one may calculate the pressure for a certain altitude as in the following table. However, this assumes that the aircraft causes the same &quot;boom intensity&quot; at that altitude, which you should doubt at least for the SR-71.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Aircraft        speed   altitude        pressure&#xA;               [mach]   [ft (m)]        [lb/ft² (Pa)]&#xA;&#xA;SR-71           3      48,000 (15,000)  1.44 (69)&#xA;Concorde SST    2      48,000 (15,000)  2.07 (99)&#xA;F-104           1.93   48,000 (15,000)  0.8  (38)&#xA;Space Shuttle   1.5    48,000 (15,000)  1.5  (72)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;As you can see, the Concorde is the loudest aircraft, the most comparable F-104 (speed, altitude) produces just 40% of its sound pressure. But the F-104 is also much much smaller than the Concorde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Space Shuttle is very loud for its low speed. However, it looks more like a flying brick than an elegant, streamlined aircraft, so no wonder that it creates strong shock waves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SR71 seems to be very quiet for its speed, but as said, I don't think you can pull it down to 48000ft and expect the same behaviour. However, a sonic boom starts to disperse in some (larger) distance, may be this already happened for the SR-71. (Also, it's a spy plane with a very special shape - may be, this reduces the boom, too).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It has to be said that it is hard to translate the numbers into a comparable sound level, because what makes up the loudness is not only the maximum pressure, but also the rise time.&lt;br&gt;&#xA;As counter-example, the air pressure changes by 130Pa every meter of altitude (at ground), and you don't &lt;em&gt;hear&lt;/em&gt; the change of pressure when standing up from your chair (~100kPa)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, a sudden noise appears to be much louder than a noise slowly increasing to the same level - and the bang has the most sudden wave form possible. (Listen loud music with earphones - when the player clips a second, the first moment after really hurts)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Sound_pressure#Examples_of_sound_pressure&quot; rel=&quot;noreferrer&quot;&gt;long table on Wikipedia&lt;/a&gt; listing noise sources and their levels. For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Trumpet at 0.5m:                63Pa&#xA;Jack hammer at 1m:               2Pa  (I'd say: a little quite...)&#xA;Loudest human voice at 1 inch: 110Pa&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;These levels are &lt;em&gt;effective sound pressure&lt;/em&gt;. To translate a perfect N-wave with given maximum pressure to effective pressure, you have to multiply the value by $\frac{1}{\sqrt{3}}\approx0.577$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Thus, the sonic boom of the Concorde has an effective value of 57Pa, which is comparable to the trumpet in 0.5m distance.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(As said, there is still a difference, because the boom is a sharp, short noise, but it gives an idea.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;By the way, I just stumbled &lt;a href=&quot;http://acousticstoday.org/wp-content/uploads/2015/06/Concorde-Booms-and-the-Mysterious-East-Coast-Noises-Peter-H-Rogers-and-Domenic-J.-Maglieri.pdf&quot; rel=&quot;noreferrer&quot;&gt;on another document&lt;/a&gt;, about primary and secondary sonic booms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YZYUM.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YZYUM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It states that you hear a primary sonic boom coming from the aircraft within a lateral distance of ~20nm (solid lines) as well as a secondary boom within a distance of 60-85nm (dashed lines). This secondary waves are a reflection of the upwards travelling shockwaves from the aircraft at the atmosphere. &#xA;The secondary boom is not a short, loud bang, but a longer and less intense rumbling, making it difficult to identify the source. &lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="22661" LastEditDate="2017-06-25T01:18:48.307" LastActivityDate="2017-06-25T01:18:48.307" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17671" PostTypeId="2" ParentId="8560" CreationDate="2015-08-07T12:03:48.113" Score="2" Body="&lt;p&gt;Torque is more noticeable in aircraft with tail wheels (tail draggers) which also have large engines (e.g. world war 2 vintage) for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;If the throttle is advanced too quickly, you might not have enough airflow over the rudder to be able to counteract it and a swing followed by a ground loop could result.&lt;/li&gt;&#xA;&lt;li&gt;At the point when the tail is lifted off the ground during the take off run, gyroscopic effects occur that could cause a swing (try holding a spinning top and then move it around - it exerts forces in unexpected directions).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Also on aircraft with the largest engines, the torque could make one wing lower than the other during the take off run. You also have the problem going around to be very careful with both throttle and rudder because these effects are more pronounced at lower airspeeds where airflow is less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aeroplane with a nosewheel is generally more stable on the ground (due to the CG being ahead of the main wheels rather than behind), so these effects are less noticeable.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-08-07T14:26:04.637" LastActivityDate="2015-08-07T14:26:04.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17672" PostTypeId="1" AcceptedAnswerId="24346" CreationDate="2015-08-07T14:33:15.413" Score="29" ViewCount="2198" Body="&lt;p&gt;I found this clip online that shows the speed tape on the Lockheed U-2 going what I perceive is the opposite direction to the 'normal' convention. On most aircraft, the higher values are above and so the tape scrolls downwards, but in this case it is mirrored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Observe indicator on left for the first few seconds in the following clip:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/q48Swb2ATww?start=10&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a photo as well from a &lt;a href=&quot;http://www.air-defense.net/forum/topic/186-us-air-force/page-5&quot; rel=&quot;noreferrer&quot;&gt;french forum&lt;/a&gt;, actual source unknown:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/DJ1Yz.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why do this? On every aircraft I can think of it is the opposite.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the fact that you pitch down, speed increases? Then you got the speed/altitude indicators moving in different directions, so I don't see how that would make it any more clear, especially when it appears it's the only aircraft doing this.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-07T15:58:07.007" LastActivityDate="2016-01-14T21:10:36.443" Title="Why does the speed tape on the Lockheed U-2 go the opposite way?" Tags="&lt;military&gt;&lt;flight-instruments&gt;&lt;glass-cockpit&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17673" PostTypeId="1" AcceptedAnswerId="17681" CreationDate="2015-08-07T14:41:13.150" Score="0" ViewCount="368" Body="&lt;p&gt;I just really don't understand how an airplane can fly with greater weight than lift.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-08-07T16:18:52.583" LastActivityDate="2015-08-07T16:23:48.643" Title="Can an airplane fly with greater weight than lift and how?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="10" ClosedDate="2015-08-07T16:23:45.843" ContentLicense="CC BY-SA 3.0" />
  <row Id="17674" PostTypeId="1" AcceptedAnswerId="17675" CreationDate="2015-08-07T15:06:19.980" Score="1" ViewCount="735" Body="&lt;p&gt;I was just wondering one day about because the 787 uses a wing flex to reduce wing tip vortex, but back in World War 2 they didn't know about wing tip vortex, so then why would it be curved upwards?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nJlyT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nJlyT.jpg&quot; alt=&quot;B-29 Bomber 3-view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see in the middle picture the wing is curved upwards. I see this on a lot of commercial airplanes too like the Boeing 737&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-08-07T15:57:29.113" LastActivityDate="2015-08-08T12:43:48.530" Title="Why do older airplanes have the wing curved upward like a 787?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="15" FavoriteCount="1" ClosedDate="2015-08-07T16:20:08.440" ContentLicense="CC BY-SA 3.0" />
  <row Id="17675" PostTypeId="2" ParentId="17674" CreationDate="2015-08-07T15:18:23.827" Score="13" Body="&lt;p&gt;You are confusing 2 concepts here, dihedral and winglets. What you are showing in the picture is &lt;a href=&quot;https://en.wikipedia.org/wiki/Dihedral_(aeronautics)&quot;&gt;dihedral&lt;/a&gt;, which is not a curvature but an angle positive from the horizontal. This angle helps improve lateral (roll) stability in flight. This is nothing new, almost all commercial jets have dihedral. Winglets improve efficiency. A Boeing 787 has both. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-08-08T12:43:48.530" LastActivityDate="2015-08-08T12:43:48.530" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17676" PostTypeId="1" AcceptedAnswerId="17677" CreationDate="2015-08-07T15:20:19.093" Score="14" ViewCount="8735" Body="&lt;p&gt;I've wondered this question because if the horizontal stabilizer is longer than that means more lift. My guess to this question would be the result of wing tip vortex strength on a longer wing&lt;a href=&quot;https://i.stack.imgur.com/47cpB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/47cpB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="64" LastEditDate="2015-08-07T15:26:56.833" LastActivityDate="2019-08-10T03:53:59.520" Title="Why can't horizontal stabilizers be longer than they are today?" Tags="&lt;aircraft-design&gt;" AnswerCount="6" CommentCount="14" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17677" PostTypeId="2" ParentId="17676" CreationDate="2015-08-07T15:26:50.080" Score="46" Body="&lt;p&gt;The horizontal stabilizers &lt;em&gt;can&lt;/em&gt; be longer, they just don't &lt;em&gt;need&lt;/em&gt; to be any longer than they are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each additional square inch will add &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift-induced_drag&quot;&gt;induced drag&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Parasitic_drag&quot;&gt;parasitic (form / profile) drag&lt;/a&gt; which costs fuel so they're not made any bigger than necessary to provide adequate control of the plane.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="39" LastEditDate="2015-08-08T20:22:25.380" LastActivityDate="2015-08-08T20:22:25.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17678" PostTypeId="2" ParentId="17646" CreationDate="2015-08-07T15:27:55.427" Score="5" Body="&lt;p&gt;This question has been discussed a couple of times on the AOPA forums (members only) and the conclusion there was that it's completely fine to trust the automated identification. If the system is fully certified for IFR then why wouldn't you trust it? And if you don't trust one specific feature then why should you trust any of them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Identifying NAVAIDs correctly is in the &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/faa-s-8081-4e.pdf&quot;&gt;instrument PTS&lt;/a&gt; but the FAA doesn't require any specific method of checking. In my last instrument checkride I used a G1000 and the DPE had no problem with me using the automatic identification; that's what it's there for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said all that, things can and do go wrong, so cross-checking against other sources is still a good idea. For example, when you load a VOR approach from the database, the G1000 will automatically tune NAV1 to the NAVAID frequency and identify it. If either the frequency or the name doesn't match what's on the approach plate - or if the name is missing because it couldn't be identified - then something is wrong and you need to investigate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately I think this is a question of comfort level, both personally and with the equipment. Some people will check the morse ID directly every time, out of habit or preference. Others won't, because they're confident that they know the equipment well enough not only to trust it, but also to identify and handle any problems.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-07T15:27:55.427" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17681" PostTypeId="2" ParentId="17673" CreationDate="2015-08-07T16:18:14.583" Score="2" Body="&lt;p&gt;There are many situations where the weight is not equal to the lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is, per definition, the aerodynamic force perpendicular to the undisturbed incoming airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weight of the aircraft is due to gravity, hence pointing down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a steady situation in which the lift is not equal to the weight is the climb phase. During climb the lift is actually less than the weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your comment you mention a weight-to-lift ratio of 5 : 4. If that would be during an unaccelerated climb, the flight path angle would be 37 degrees and the thrust minus drag would have to be 60% of the weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image below shows the weight vector $W$, lift vector $L$, and excess thrust vector $T$ in a ratio 5:4:3. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The combination of the lift and thrust vectors is equal is size and opposite to the weight vector. It is denoted $W'$ in the image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity I left drag out of the image and assumed thrust is purely acting in the direction of travel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GcgXb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GcgXb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-08-07T16:23:48.643" LastActivityDate="2015-08-07T16:23:48.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17682" PostTypeId="2" ParentId="17676" CreationDate="2015-08-07T16:23:44.980" Score="3" Body="&lt;p&gt;Concorde designers took a different approach: they removed the horizontal tail planes to decrease drag as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every unnecessary thing (pod/pylon/etc.) on the outside of the fuselage or under the wings add drag, even without generating lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another historical example is the MD-11, evolution of the DC-10. If you notice, the MD-11, even if longer and heavier, has smaller tail planes for better cruise performance.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-08-07T16:23:44.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17683" PostTypeId="2" ParentId="17676" CreationDate="2015-08-07T16:34:59.613" Score="20" Body="&lt;p&gt;On most aircraft, the horizontal surfaces in the rear are horizontal stabilizers. These surfaces actually provide negative lift, which balances the center of gravity being forward of the center of the lift force. This balance of forces provides natural stability in a simple way, which is why is is the standard design for both large and small aircraft. Of course this negative lift is working against the main wing, which increases the drag, so this surface is kept as small as possible to provide sufficient stability with as little drag as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an aircraft layout called &lt;a href=&quot;https://en.wikipedia.org/wiki/Tandem_wing&quot; rel=&quot;noreferrer&quot;&gt;tandem wing&lt;/a&gt;, where there are two wings in a tandem configuration that both provide upwards lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FQOWR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FQOWR.jpg&quot; alt=&quot;Tandem wing aircraft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-08-07T16:34:59.613" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="17684" PostTypeId="2" ParentId="17648" CreationDate="2015-08-07T16:41:20.923" Score="5" Body="&lt;p&gt;The engine is compressing air to more efficiently burn fuel. If you remove the fuel, there is no reason to compress the air. Other systems that run off of the engine bleed air only do so because it is a convenient source. The 787 uses a bleedless model that runs off of electric power instead of engine bleed air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electric airplanes are certainly an option, but &lt;a href=&quot;https://aviation.stackexchange.com/q/15163/1696&quot;&gt;a propeller is a better option than a turbine engine&lt;/a&gt;. You could however &lt;a href=&quot;https://aviation.stackexchange.com/q/9940/1696&quot;&gt;keep the duct around the prop&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-07T16:41:20.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17685" PostTypeId="1" AcceptedAnswerId="17686" CreationDate="2015-08-07T17:23:25.357" Score="5" ViewCount="1056" Body="&lt;p&gt;Jetliners usually have their engines mounted on the wings, so what is the exhaust port on the tail for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://s23.postimg.cc/osq3ssoh7/47cp_B.jpg&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="2294" LastEditorUserId="2294" LastEditDate="2019-08-06T20:18:36.783" LastActivityDate="2019-08-06T20:18:36.783" Title="What is the exhaust port on the tail of jetliners for?" Tags="&lt;commercial-aviation&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ClosedDate="2015-08-07T17:31:50.137" ContentLicense="CC BY-SA 4.0" />
  <row Id="17686" PostTypeId="2" ParentId="17685" CreationDate="2015-08-07T17:29:42.823" Score="9" Body="&lt;p&gt;That's the exhaust port for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;noreferrer&quot;&gt;APU&lt;/a&gt; (Auxillary Power Unit).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The APU is usually used to power on-board electronics when at the gate, or used to start the main engines. They may or may not be running while in-flight.&lt;/p&gt;&#xA;" OwnerUserId="9567" LastActivityDate="2015-08-07T17:29:42.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17687" PostTypeId="1" AcceptedAnswerId="17689" CreationDate="2015-08-07T17:42:23.980" Score="17" ViewCount="3692" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12452/what-is-the-typical-aircrew-for-a-cargo-flight&quot;&gt;This question&lt;/a&gt; talks a bit about the crews that are involved in a commercial cargo flight, but I'm wondering if Cargo flights every carry other sorts of people on their flights?  Say, a photographer to take pictures of operations for advertising or something.  Or maybe one of the crews kids who want's to see what Mom does or something like that.  Or, perhaps there's even another person who's normally there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they do, here's a couple bonus questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do they have jump seats?  And are they in the cockpit, or in the cargo hold?  (Just in general, I assume different planes have different setups).&lt;/li&gt;&#xA;&lt;li&gt;Are there any regulations regarding this?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-08-07T22:38:17.923" Title="Do Cargo flights carry anyone other than the crew?" Tags="&lt;faa&gt;&lt;crew&gt;&lt;cargo&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17688" PostTypeId="2" ParentId="17687" CreationDate="2015-08-07T17:53:56.983" Score="2" Body="&lt;p&gt;Yes actually I have an uncle who flew on a c-130 cargo plane to Alaska that was carrying jet fuel if you consider that cargo. The plane he was on was refueling jets in the sky. So yes sometimes they do carry people on planes with cargo. And it usually when its only necessary.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-07T17:53:56.983" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="17689" PostTypeId="2" ParentId="17687" CreationDate="2015-08-07T18:04:51.183" Score="15" Body="&lt;p&gt;Yes, cargo aircraft are like other aircraft in that there is generally at least a jump seat available. Especially larger aircraft will also have &lt;a href=&quot;//www.nycaviation.com/2015/02/anatomy-freighter/&quot; rel=&quot;noreferrer&quot;&gt;additional jump seats, a lavatory, and a galley&lt;/a&gt;. This area can be used for relief crew, or other crew that are &lt;a href=&quot;//en.wikipedia.org/wiki/Federal_Express_Flight_705&quot; rel=&quot;noreferrer&quot;&gt;just deadheading&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are exceptions though. The upper deck of the 747 is &lt;a href=&quot;//www.boeing.com/resources/boeingdotcom/company/about_bca/startup/pdf/freighters/747BCF.pdf&quot; rel=&quot;noreferrer&quot;&gt;larger&lt;/a&gt; than just the cockpit, even on the &lt;a href=&quot;//www.airliners.net/photo/0717207/M/&quot; rel=&quot;noreferrer&quot;&gt;cargo&lt;/a&gt; &lt;a href=&quot;//www.boeing.com/resources/boeingdotcom/company/about_bca/startup/pdf/freighters/747-400f.pdf&quot; rel=&quot;noreferrer&quot;&gt;versions&lt;/a&gt;. There is more room in the back for additional crew. The &lt;a href=&quot;//www.airlinereporter.com/2013/02/photos-an-inside-look-of-an-antonov-an-124/&quot; rel=&quot;noreferrer&quot;&gt;An-124&lt;/a&gt; and An-225 also have additional space for crew behind the cockpit. The extra crew can be loadmasters, navigators, mechanics, or other functions that can make it easier to operate in and out of airports with less services available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the upper deck of a 747-400F:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ptJ3r.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ptJ3r.jpg&quot; alt=&quot;747-400F Upper Deck Layout&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-08-07T20:00:56.960" LastActivityDate="2015-08-07T20:00:56.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17690" PostTypeId="2" ParentId="16036" CreationDate="2015-08-07T18:13:47.140" Score="-2" Body="&lt;p&gt;777-200-PW 4077&#xA;RR 877&#xA;GE90-77B&#xA;777-200ER-PW 4090&#xA; RR 895&#xA; GE90-94B&#xA;777-200Lr/freighter-GE90-110B1&#xA; GE90-115B1&#xA;777-300-PW 4098&#xA; RR 892&#xA; GE90-92B/-94B&#xA;777-300ER- GE90-115B1&#xA;777-8x/9x-GE9X&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; Got the information from wikipedia&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-08-08T05:22:51.417" LastActivityDate="2015-08-08T05:22:51.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17691" PostTypeId="2" ParentId="17676" CreationDate="2015-08-07T18:20:56.530" Score="13" Body="&lt;p&gt;The tail surfaces of an aircraft are also called the &quot;empennage&quot;, a term originating from the French word for the fletching of an arrow. The term thus indicates the purpose. The horizontal and vertical stabilizers are exactly that, stabilizers. Their purpose is to keep the plane's fuselage in line with the relative wind caused by the aircraft moving through the air. Without them, the plane could easily enter a sideslip or a tumble. They also provide pitch and yaw control by redirecting the relative wind upward or downward, having the opposite effect on the airframe (Newton's third law).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not intended to generate lift to counter gravity, and in many cases the horizontal stabilizer does just the opposite, providing a downward force on the back of the aircraft through a combination of negative pitch and &quot;downwash&quot; of air from the wings. This keeps the nose up during forward flight, compensating for a slightly nose-heavy weight distribution which in turn provides desirable flight characteristics such as the tendency to nose-down in a stall (if you're going to fall out of the sky, you might as well fall in an attitude that restores a low angle of attack and thus has the potential for you to recover).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, in a traditional configuration, they aren't any bigger than they are because they don't have to be. A larger horizontal stabilizer will increase drag due to the greater surface area and volume of displaced air, for no real gain. Potentially the control surface area could be increased, but there is a limit to how big they can be before the forces acting on the control surface in a deflected position exceed the materials strength of the control surface or the airframe. Even before that, larger control surfaces make the plane more sensitive to stick/yoke input, which is useful for a fighter or aerobatic airplane, but potentially deadly for a plane designed for use by the &quot;everyman&quot; pilot.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-04T18:34:14.223" LastActivityDate="2015-09-04T18:34:14.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17693" PostTypeId="1" AcceptedAnswerId="17696" CreationDate="2015-08-07T18:36:42.233" Score="10" ViewCount="1781" Body="&lt;p&gt;Let's imagine a swarm of fighter jets intercepting another swarm. Both groups are moving head-on towards each other. Once they get in range, they will probably lock on and fire missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do fighter jets have radar that will show and warn of a missile &lt;strong&gt;coming head on?&lt;/strong&gt; Or do they &lt;strong&gt;only&lt;/strong&gt; scan their tails?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in when, if ever, such capability was implemented. To me it seems like the 50's and 60's and maybe even the 70's, they would only worry about scanning their tails. It would also be good to document this for both NATO and Warsaw Pact jets.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1696" LastEditDate="2018-04-14T23:53:15.533" LastActivityDate="2018-04-14T23:53:15.533" Title="Do fighter jets have forward-looking radar warnings for missiles, and when was this first implemented?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;missiles&gt;&lt;missile-lock&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17696" PostTypeId="2" ParentId="17693" CreationDate="2015-08-07T18:55:09.700" Score="10" Body="&lt;p&gt;Radar Warning Receiver systems (RWRs) used by military aircraft are omnidirectional. However, they do not warn of incoming missiles (unless that missile is at least semi-actively radar-guided, like an AMRAAM). What they warn of are various patterns of radar activity, including a radar lock (which is a constant, high-intensity scanning of the aircraft's position, more than just a &quot;blip&quot; as the antenna passes by on a wide-angle scan pattern).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If another aircraft has a radar lock on you, you should be expecting an incoming missile of some kind. However, IR missiles (AIM-9 Sidewinder, AA-11 Archer, MICA IR, ASRAAM) do not emit any EMR that indicates they're incoming; they use a passive FLIR sensor to identify and track the heat source they were told to kill (they don't even require a radar lock; the seeker can be cued to a pilot's helmet, or it can be &quot;uncaged&quot; and will lock on to the most significant heat source in front of it). Passive radar-guided missiles like the old AIM-7 Sparrow also do not emit their own radar; they track the radar returns from the firing aircraft. Only semi-active and active radar-homing missiles emit their own radar noise that can be used by the RWR to know one is on the way. A few older passive missile systems used radio control to guide the missile to the target, and RWRs can also detect these &quot;sideband&quot; radio signals as a clue a missile has been launched.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More modern Missile Approach Warning Systems (MAWS) have additional features that can help detect and track incoming missiles of multiple types. The biggest clue of a missile launch is a new heat signature, especially in the direction of an incoming radar lock; a suite of IR sensors can be used by MAWS to put 2 and 2 together and warn you of the missile launch.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2016-04-13T22:15:07.370" LastActivityDate="2016-04-13T22:15:07.370" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="17699" PostTypeId="1" AcceptedAnswerId="17701" CreationDate="2015-08-07T19:06:33.000" Score="5" ViewCount="363" Body="&lt;p&gt;Watching &lt;a href=&quot;https://youtu.be/i3UWDsUBvRQ?t=51s&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;, it appears that the hydraulic ram intrudes into the cargo space and would run into the Unit Load Device &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;(ULD)&lt;/a&gt; that was stowed there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a special ULD that is loaded on each flight to clear the ram, or is there enough clearance that any ULD will fit in this spot?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2015-08-07T19:50:45.663" Title="Is there a special ULD to be loaded at the main cargo door?" Tags="&lt;cargo&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17701" PostTypeId="2" ParentId="17699" CreationDate="2015-08-07T19:45:26.887" Score="7" Body="&lt;p&gt;No, the container near the door is the same as the others. The containers &lt;a href=&quot;https://www.youtube.com/watch?v=8402ivGimug&quot; rel=&quot;noreferrer&quot;&gt;do not fill the entire cabin all the way around&lt;/a&gt;, which leaves enough space above for things like the door hydraulics. The containers on the upper cargo area below are all 88&quot; x 125&quot;, which corresponds to a standard &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;LD7 container&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AOFTb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AOFTb.jpg&quot; alt=&quot;767 Freighter Capacity&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.ups.com/aircargo/using/services/services/domestic/svc-aircraft.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-08-07T19:50:45.663" LastActivityDate="2015-08-07T19:50:45.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17702" PostTypeId="1" AcceptedAnswerId="17705" CreationDate="2015-08-07T20:30:17.060" Score="5" ViewCount="7309" Body="&lt;p&gt;The &lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/55a4bdb940f0b61562000001/AAR_1-2015_G-EUOE.pdf&quot; rel=&quot;noreferrer&quot;&gt;accident report&lt;/a&gt; on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Accidents_and_incidents_involving_the_Airbus_A320_family#A319&quot; rel=&quot;noreferrer&quot;&gt;A319 G-EUOE incident&lt;/a&gt; in May 2013 mentions &quot;manual thrust&quot;, and implies that using it is very unusual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The autothrust system failed, requiring the use of manual thrust:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The autothrust system cannot operate  in N1 mode and so was&#xA;  unavailable for the remainder of the flight, which was  flown using&#xA;  manual thrust&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the pilot hadn't used manual thrust outside a sim session for seven years (and the co-pilot had &lt;em&gt;never&lt;/em&gt; used it outside the sim):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The commander informed the AAIB that, excluding simulator training, he&#xA;  had  last flown the A320-series aircraft using manual thrust seven&#xA;  years before the accident&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That implies that autothrust is always used in normal operations, and manual thrust is an emergency backup only. What exactly are autothrust and manual thrust and why is using manual thrust so unusual?&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2021-01-08T11:04:22.303" Title="What are autothrust and manual thrust on an A320 (or other aircraft)?" Tags="&lt;engine-failure&gt;&lt;airbus-a320&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17703" PostTypeId="2" ParentId="17687" CreationDate="2015-08-07T20:38:57.737" Score="11" Body="&lt;p&gt;Some airlines operate their aircraft in a combination of freighter and passenger aircraft. See &lt;a href=&quot;https://www.klm.com/travel/us_en/prepare_for_travel/on_board/seating_plans/747-400Combi.htm&quot;&gt;here&lt;/a&gt; for the floor plan of &lt;a href=&quot;https://en.wikipedia.org/wiki/KLM&quot;&gt;KLM&lt;/a&gt;'s &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-400#747-400M&quot;&gt;Boeing 747-400M Combi&lt;/a&gt;. It has a large cargo door at the rear fuselage for loading freight containers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/United_Nations_Humanitarian_Air_Service&quot;&gt;Humanitarian relief flights&lt;/a&gt; have an obligation to carry journalists along if they wish. Some governments have instituted a policy of transparency so the press may observe first-hand where the goods are delivered to.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-08-07T20:38:57.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17704" PostTypeId="1" AcceptedAnswerId="17707" CreationDate="2015-08-07T20:46:29.500" Score="1" ViewCount="802" Body="&lt;p&gt;Every time I have landed on a airplane reverse thrust is needed, but what if the runway is 18,000ft long. Because if the runway is longer couldn't you save fuel by not using the reverse exhaust&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-08-07T20:56:21.633" LastActivityDate="2015-08-07T21:13:06.470" Title="Is reverse thrust needed on a long runway" Tags="&lt;airliner&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="0" ClosedDate="2015-08-08T09:48:07.103" ContentLicense="CC BY-SA 3.0" />
  <row Id="17705" PostTypeId="2" ParentId="17702" CreationDate="2015-08-07T20:56:45.127" Score="8" Body="&lt;p&gt;Manual thrust means that the engine thrust corresponds directly to the position of the thrust lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autothrust means that a target speed is dialed into the system (using a knob that is usually located on the glare-shield) and the auto-thrust system automatically adjusts the engines to maintain that speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in an aircraft with classical controls the longitudinal stability means the aircraft tends to maintain speed with pitch and pilots basically need to use thrust to climb or descend and yoke to adjust speed, always making adjustments with the other control as well to avoid oscillations and compensate for the more complex parts of the power-pitch relationship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, it is usually recommended to fly either fully manual or fully automatic (autopilot+autothrust).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But Airbus A320 and newer (A319 is just a variant of A320) changes that with the artificial neutral stability in normal control law. Even with autopilot off, the flight computer automatically adjusts trim so that the aircraft flies straight so that adding power makes the aircraft accelerate and reducing it makes it decelerate. However pushing the stick forward to descend will still make the aircraft accelerate and pulling it to climb will make it slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, Aibrbus aircraft are easier to fly with autothrust always on (except for take-off roll; autothrust is disabled when the power levers are advanced above certain position, which is only done for take-off and in emergency where extra power is needed).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-08-07T21:19:02.690" LastActivityDate="2015-08-07T21:19:02.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17706" PostTypeId="1" AcceptedAnswerId="18729" CreationDate="2015-08-07T21:09:09.040" Score="8" ViewCount="5511" Body="&lt;p&gt;All jet engines have the same method of air flowing into the engine, which is compressed and ignited. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can engine designers do to make an engine design create more thrust? For example, what is different when comparing the Olympus engines on the supersonic Concorde to the CFM56 engines on a 737?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="39" LastEditDate="2015-08-07T23:06:41.040" LastActivityDate="2015-08-08T21:17:25.027" Title="How does a supersonic jet engine differ from a subsonic jet engine?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-15T07:56:44.023" ContentLicense="CC BY-SA 3.0" />
  <row Id="17707" PostTypeId="2" ParentId="17704" CreationDate="2015-08-07T21:12:24.087" Score="7" Body="&lt;p&gt;Reverse thrust is &lt;strong&gt;never needed&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A reverse thrust is relatively complex thing that can easily fail and for this reason when deciding whether an aircraft can land at some runway, the calculations are done &lt;em&gt;without&lt;/em&gt; assuming reverse thrust. And of course the stopping distance for aborted take-off is also without thrust reverser, because if your engine failed, it won't provide any.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason to use reverse thrust is to reduce wear of the brakes and tires. The kinetic energy of the aircraft is &lt;em&gt;huge&lt;/em&gt; and when it gets converted to heat in the brakes, they can get pretty hot. So &lt;em&gt;if available&lt;/em&gt;, pilots always use reverse thrust to ease the brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But it's not a big deal if not available. Thrust reversers are on MEL (minimum equipment list) for most if not all aircraft meaning the aircraft can be dispatched with thrust reversers inoperative. The brake wear will be higher from the more intensive braking, but it is better than having a plane wait for spare parts at some remote location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding long runways, there is almost always a possibility to turn off the runway earlier, which often saves time for the aircraft (shorter route to taxi) and makes the runway available for next aircraft sooner. So pilots usually still want to use some reasonable braking.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-07T21:12:24.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17708" PostTypeId="2" ParentId="17704" CreationDate="2015-08-07T21:13:06.470" Score="2" Body="&lt;p&gt;Aircraft don't need thrust reversers on a long runway, in fact they often don't need it at all. It just helps in decelerating, reducing the wear and tear of the brakes and tires. That comes at the cost of fuel, but it saves on downtime replacing brake discs and tires. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason to use the reverser is that sometimes it saves taxi time to take an earlier runway exit. This saves fuel and time = money. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-08-07T21:13:06.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17709" PostTypeId="2" ParentId="17702" CreationDate="2015-08-07T21:40:25.497" Score="5" Body="&lt;p&gt;To add one piece of information to Jan's answer, quoting from the A320 Flight Crew Training Manual, a detailed description of &lt;code&gt;what exactly is autothrust&lt;/code&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;OBJECTIVE&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The A/THR computer (within the FG) interfaces directly with the engine computer, referred to as the FADEC. The A/THR sends to&#xA;  the FADEC the thrust targets that are needed to:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Obtain and maintain a target speed, when in SPEED mode&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Obtain a specific thrust setting (e.g. CLB, IDLE), when in THRUST&#xA;  mode.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;INTERFACE&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When the A/THR is active, the thrust lever position determines the maximum thrust that the A/THR can command in SPEED or&#xA;  THRUST mode. Therefore, with A/THR active, thrust levers act as a&#xA;  thrust limiter or a thrust-rating panel. The A/THR computer does not&#xA;  drive back the thrust levers. The PF sets them to a specific detent on&#xA;  the thrust lever range.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The A/THR system provides cues that indicate the energy of the&#xA;  aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Speed, acceleration, or deceleration, obtained by the speed trend&#xA;  vector&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• N1, and N1 command on the N1 gauge.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;All these cues are in the flight crew’s direct line of vision. In&#xA;  other words, the Thrust Lever Angle (TLA) should not be used to&#xA;  monitor correct A/THR operation. Neither should the thrust lever&#xA;  position of a conventional autothrottle, be considered a cue because,&#xA;  in many hazardous situations, the thrust lever position can be&#xA;  misleading (e.g. engine failure, thrust lever jammed).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IeWfJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IeWfJ.png&quot; alt=&quot;A320 TLP detents meaning&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A/THR can only be active, when the thrust levers are between IDLE&#xA;  and the CLB detent. &#xA;  When the thrust levers are beyond the CLB detent,&#xA;  thrust is controlled manually to the thrust lever Angle, and the A/THR&#xA;  is armed . This means that the A/THR is ready to be re-activated, when&#xA;  the flight crew sets the thrust levers back to the CLB detent (or&#xA;  below).A/THR appears in blue on the FMA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M0fMK.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M0fMK.png&quot; alt=&quot;A320 Normal operation throttle interface&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If thrust levers are set to IDLE, A/THR is set to off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;AP, FD, A/THR SYSTEM INTEGRATION&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There is a direct relationship between aircraft pitch control, and engine thrust control. This&#xA;  relationship is designed to manage the aircraft’s energy.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• If the AP/FD pitch mode controls a vertical trajectory (e.g. ALT,&#xA;  V/S, FPA, G/S): &lt;strong&gt;A/THR controls speed&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• If the AP/FD pitch mode&#xA;  controls a speed (e.g. OP CLB, OP DES): &lt;strong&gt;A/THR controls thrust&lt;/strong&gt; (THR&#xA;  CLB, THR IDLE) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• If no AP/FD pitch mode is engaged (i.e. AP is off and&#xA;  FD is off): &lt;strong&gt;A/THR controls speed&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Therefore, any change in the AP/FD pitch mode is associated with a&#xA;  change in the A/THR mode.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On the other hand, manual thrust is a conventional and proportional interpretation of the position of the TLP: 0% throttle at IDLE, 100% at TOGA  and linearly interpolated inbetween.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for why the A/THR is seldomly not used, from the same manual (emphasis mine): &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Use of A/THR is recommended during the entire flight. &#xA;  &lt;strong&gt;It may be used in most failures cases&lt;/strong&gt;, including:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Engine failure, even during autoland&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Abnormal configurations&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-08-07T21:47:39.123" LastActivityDate="2015-08-07T21:47:39.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17710" PostTypeId="2" ParentId="119" CreationDate="2015-08-07T22:07:40.060" Score="5" Body="&lt;p&gt;There was a lot of changes with the original 737 and the Max. &#xA;&lt;hr&gt;&#xA;First of all the original 737 had a wingspan of 93 feet the 100-500 model had this wingspan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FKELwm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FKELwm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/5MqMMm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5MqMMm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;the 737NG has a wingspan of 117.5 feet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the 737 Max has a wingspan of 118 feet, so it has more lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;Another change would be the engine, the Boeing 737 100-200 had a Pratt &amp;amp; Whitney JT8D, &lt;a href=&quot;https://i.stack.imgur.com/gAMvKm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gAMvKm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/vctg2m.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vctg2m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;the 737 300-500 had a CFM International 56-3 series &lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the 737 600-900 had a CFM International CFM56-7 series &lt;a href=&quot;https://i.stack.imgur.com/vURpLm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vURpLm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WRgQGm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WRgQGm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;and the 737Max has a CFM International LEAP-1B&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which is the most efficient engine out of the whole 737 series. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;Another major change is the winglet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The winglet started to being put on the 737NG series and it increases efficiency,and lift &lt;a href=&quot;https://i.stack.imgur.com/uNk5Jm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uNk5Jm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/82buVm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/82buVm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;but the 737 Max wing has a split tip winglet which increases efficiency and lift by 1% over the original winglet and also the wing is raked like a Boeing 787 to reduce wing tip vortex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;Another major change is lower fuel costs than the original 737 and lower operation costs. &#xA;&lt;hr&gt;Another change would be the tail cone which is more efficient.&lt;a href=&quot;https://i.stack.imgur.com/Cm5xqm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cm5xqm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;Second to last major change would be touchscreen screens on the back of the seats which modern airplanes like the 787 and the A350 have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ubp2Nm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ubp2Nm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nb3Jqm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nb3Jqm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;hr&gt;The last major change is the sky interior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/P3ohLm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/P3ohLm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="14897" LastEditDate="2017-09-28T00:07:02.257" LastActivityDate="2017-09-28T00:07:02.257" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17711" PostTypeId="2" ParentId="17687" CreationDate="2015-08-07T22:38:17.923" Score="13" Body="&lt;p&gt;I spent many an hour crammed into the jumpseats of 727's (they have 2, both in the broom closet sized cockpit with 3 crew members). I worked as a cargo handler at the FedEx hub in Memphis and at the time we could book any open jumpseat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When i clocked out at 4am there were a couple hundred planes just about to depart for destinations all over the world. It was awesome, but alas, no more. It even continued after an off duty pilot with a hammer decided to try and hijack one of our planes from the jumpseat. But 19 jerks ended all that on Sep 11, 2001. There are still non-crew persons in the jumpseat but now you have to have a good reason to be there. It's mostly deadheading pilots but anybody that has an &quot;operational need&quot; for the company can jumpseat. So if they need a mechanic somewhere or something like that they can go. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as what jumpseats there are it differs by aircraft. Like i mentioned the 727's had 2 terribly uncomfortable seats in the cockpit. The dc10's I've flown on had one in the cockpit and either 2 or 4 against the bulkhead facing backward. [Think Tom Hanks in Castaway. That was very accurate, you're staring at the first set of cargo containers behind a safety net the whole flight.] In the 747-100 there were about 10 airline seats in the upper deck and two bunks at the back. The 747-200's were the nicest. They were formerly passenger planes so the upper deck still had the first class seating. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-07T22:38:17.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17712" PostTypeId="1" AcceptedAnswerId="17713" CreationDate="2015-08-07T22:48:46.080" Score="5" ViewCount="8032" Body="&lt;p&gt;I've always seen a button either built into the yoke or attached to the yoke with velcro on older aircraft. However, the other day my instructor used an older-looking headset that had a push to talk button built into the side of the headphones. He had no cable plugged in except the mic/headphone jacks and never touched the yoke's PTT button to transmit. My question is: how is the PTT function activated? Is this done with a load resistor or something that loads down the mic line, triggering radio transmission? I've done some research and looked at various manuals of audio panels and navcoms and haven't found an answer. The audio panel in use in this case is the Garmin GMA-430 audio panel, pictured here: &lt;a href=&quot;https://i.stack.imgur.com/WdwNl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WdwNl.jpg&quot; alt=&quot;here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2017-01-20T18:14:52.400" Title="How does the PTT button on the radio work?" Tags="&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="17713" PostTypeId="2" ParentId="17712" CreationDate="2015-08-07T23:05:16.073" Score="5" Body="&lt;p&gt;The standard microphone plug on GA planes is the PJ-068 plug, which has three electrical contacts (tip, ring, and sleeve). The tip of this connector is a push-to-talk signal (the ring carries the actual audio signal, the sleeve is ground). &lt;/p&gt;&#xA;" OwnerUserId="923" LastActivityDate="2015-08-07T23:05:16.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17714" PostTypeId="1" CreationDate="2015-08-08T00:41:56.213" Score="18" ViewCount="3613" Body="&lt;p&gt;Every HUD I've seen, whether photographs or in video games, uses green light to draw the lines and text.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why green? I thought red was a better color for pilots' eyes so they can stay adjusted for night vision. Do HUD's allow you to switch colors at night?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I'm interested in military aircraft only, especially fighter jets. But if the reason happens to be the same across the military and civilian world, that's fine too of course.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1696" LastEditDate="2018-04-14T23:53:49.527" LastActivityDate="2019-04-05T19:30:56.990" Title="Why are HUDs usually green instead of red?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;hud&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="17715" PostTypeId="2" ParentId="17714" CreationDate="2015-08-08T05:09:31.830" Score="9" Body="&lt;p&gt;Studies show that our eyes see green better than any other color in both day and night. There is an article about &lt;a href=&quot;http://www.officer.com/article/10643657/the-skinny-on-lasers&quot; rel=&quot;nofollow noreferrer&quot;&gt;the difference between green and red lasers on guns&lt;/a&gt; and how you can actually seen green better in day and night so that's why the color is green.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MFj1G.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MFj1G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;From &lt;a href=&quot;https://web.archive.org/web/20150914155956/http://www.hurricanehunters.com/gallery_flying.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this gallery&lt;/a&gt; is a picture of a HUD -- look at how visible and bright it is.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="5517" LastEditDate="2019-04-05T19:30:56.990" LastActivityDate="2019-04-05T19:30:56.990" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="17716" PostTypeId="2" ParentId="14705" CreationDate="2015-08-08T05:39:01.560" Score="-3" Body="&lt;p&gt;It is because they already have several ways of braking, so they don't need reverse exhaust.&lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; This should explain to you the braking systems used by the f-16 instead of reverse exhaust. This jet you are describing may not have as many braking systems as a normal jet does so it uses reverse exhaust.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2015-08-21T13:03:59.527" LastActivityDate="2015-08-21T13:03:59.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17718" PostTypeId="1" AcceptedAnswerId="17721" CreationDate="2015-08-08T06:16:19.543" Score="11" ViewCount="2764" Body="&lt;p&gt;Tupolev used to be the one of the largest airliner manufacturer comparable to Boeing and Airbus. However since the dissolution of USSR, its airliner business is declining, and only operated by a few ex-USSR or communist countries' airway. Currently narrowbody Tu154, Tu204 and regional Jet Tu-334 are still active.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to recognise Tu154, Tu204 and Tu-334, compared to their rivals with similar size?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-08-09T16:39:59.160" LastActivityDate="2019-01-04T06:35:10.017" Title="How to recognise the Tupolev Tu-154, Tu-204, and Tu-334?" Tags="&lt;airliner&gt;&lt;aircraft-identification&gt;&lt;tupolev&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="17719" PostTypeId="2" ParentId="17718" CreationDate="2015-08-08T07:31:09.327" Score="3" Body="&lt;p&gt;&lt;strong&gt;Tu-154&lt;/strong&gt; has three rear-mounted engines and triple-axle, six wheel landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tu-204&lt;/strong&gt; is perhaps the only slightly difficult one in your list. Short stubby nose and rather long engine cowlings. Mostly operated by non-western carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tu-334&lt;/strong&gt; is cancelled.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-08T08:07:51.717" LastActivityDate="2015-08-08T08:07:51.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="17720" PostTypeId="2" ParentId="17714" CreationDate="2015-08-08T08:23:28.553" Score="19" Body="&lt;p&gt;A few thoughts (a bit of personal research):&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Eyesight&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The eye is most sensitive to green color, as can be seen in this diagram:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Eyesensitivity.svg/669px-Eyesensitivity.svg.png&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At moderate to bright light levels where the cones function, the eye is more sensitive to &lt;strong&gt;yellowish-green light&lt;/strong&gt; than other colors because this stimulates the two most common (M and L) of the three kinds of cones almost equally. At lower light levels, where only the rod cells function, the sensitivity is greatest at a &lt;strong&gt;blueish-green&lt;/strong&gt; wavelength.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cyZR6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyZR6.png&quot; alt=&quot;pic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Cone-response.svg/550px-Cone-response.svg.png&quot; rel=&quot;noreferrer&quot;&gt;wikimedia.org&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Dotted R line is (night-vision) human rhodopsin 'rods'.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand, any powerful light depletes rhodopsin down requiring that they regenerate, which takes time, just that depletion takes longer with red wavelengths. I think this does not imply that green color 'automatically' screw up night vision if the display intensity is lowered enough.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Technical Limitations&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The light has to be &lt;a href=&quot;https://en.wikipedia.org/wiki/Collimated_light&quot; rel=&quot;noreferrer&quot;&gt;collimated&lt;/a&gt; to not interfere with depth perception, which complicates having multiple colours. At least in old CRT displays, this would have left you with the choice between blue, red or green. Green and Red is perhaps the color which stands out the most, but this diagram would suggest the red occurs at different wavelengths, perhaps again interfering with collimation:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Due to the complexity of wide field-of-view reflective HUD optical systems, the optical designer must use &lt;strong&gt;all means available to meet display accuracy and parallax error requirements&lt;/strong&gt;. All certified reflective HUDs today are monochromatic, generally using a narrow-band green emitting phosphor. The addition of a second color to the HUD is a desirable natural progression in HUD technology, however, one of the&#xA;  technical challenges associated with adding a second (or third) display color is maintaining the &lt;strong&gt;performance standards available in monochrome displays&lt;/strong&gt;. One method for solving this problem uses a collimator with two independent embedded curvatures, one optimized for green symbology, the other optimized for red symbology, each with a wavelength-selective coating. &lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_4.pdf&quot; rel=&quot;noreferrer&quot;&gt;Avionics Handbook, Chapter 4&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Compounding to the previous point, it may be difficult to filter through a single red color through the screen, ending with a rather broad spectrum instead:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/2/29/CRT_phosphors.png/1024px-CRT_phosphors.png&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I think the night vision would be disturbed anyway by the variety of instruments such as maps and radar. I'm also doubting a bit of the importance of night vision in combat situations.&lt;/li&gt;&#xA;&lt;li&gt;Night vision googles also use monochrome green light, despite having perhaps the greatest benefit of red light should they break and you need to continue without.&lt;/li&gt;&#xA;&lt;li&gt;Even in a pretty new BMW I drove there was only monochrome green from their own HUD. I read forums accusing systems featuring multiple colours as having inferior display quality.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="8282" LastEditDate="2019-04-04T07:44:33.200" LastActivityDate="2019-04-04T07:44:33.200" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="17721" PostTypeId="2" ParentId="17718" CreationDate="2015-08-08T08:45:10.463" Score="27" Body="&lt;p&gt;First, the Russian airplane industry is organized differently from its Western counterpart. While both have research organizations and aircraft manufacturers, in Russia and Ukraine design offices are between both. In Russia, &lt;a href=&quot;http://tsagi.com/institute/&quot; rel=&quot;nofollow noreferrer&quot;&gt;TsAGI&lt;/a&gt; does most basic research and develops aerodynamic designs which are then put into fully developed aircraft by the design offices (&lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antonov&lt;/a&gt; in Ukraine, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ilyushin&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mikoyan (MiG)&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sukhoi&lt;/a&gt;, Yakovlev or &lt;a href=&quot;https://en.wikipedia.org/wiki/Beriev&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beriev&lt;/a&gt; in Russia). The finished designs are then transferred to manufacturing plants like &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviakor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviakor in Samara&lt;/a&gt; which churn out the actual hardware. If the demand for Tupolevs goes down, Aviakor will switch to Antonovs or Ilyushins, so the fluctuation for products of a particular design office can be evened out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One consequence of this arrangement is that aerodynamicists have the first say on the shape of the aircraft. Russian designs generally have more refined aerodynamics, at the cost of a higher manufacturing effort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older airliners from the Fifties and Sixties were &lt;a href=&quot;https://aviation.stackexchange.com/questions/24115/is-the-glass-nose-tu-134-design-for-easier-conversion-to-military-use/24134?s=1%7C0.6539#24134&quot;&gt;designed with dual use in mind&lt;/a&gt;, and many of them had a glazed nose, which makes them easy to distinguish from their contemporaries from the West. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Tu-154&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This design from the 1960s is similar to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Trident&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawker-Siddeley Trident&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 727&lt;/a&gt;. Its production surpassed 1000 aircraft and ended only in 2013.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B4k2m.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B4k2m.jpg&quot; alt=&quot;Tu-154 of Uzbekistan Airways&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-154 of Uzbekistan Airways (Picture &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Tupolev_Tu-154M,_Uzbekistan_Airways_JP6144356.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Four items make it easy to identify:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The landing gear uses six-wheel bogies, which is unique among three-engined airliners.&lt;/li&gt;&#xA;&lt;li&gt;For aerodynamic refinement, heavy use of &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule/7454#7454&quot;&gt;Küchemann bodies&lt;/a&gt; is made in the T-tail intersection and for stowing the landing gear.&lt;/li&gt;&#xA;&lt;li&gt;The aerodynamic refinement also shows in the length of the conical section of the fuselage, which takes much longer to reach its cylindrical shape. This is a consequence of putting aerodynamics before ease of manufacturing.&lt;/li&gt;&#xA;&lt;li&gt;The central air intake is of elongated shape, while that of the Boeing 727 is round and the one of the Trident was a heavily rounded triangle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Tu-204&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Intended to replace the Tu-154, this two-engined airliner flew first in 1989 and looks similar to a Boeing 757. It is still in production, but less than 100 have been produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QBr8O.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QBr8O.jpg&quot; alt=&quot;Tu-204&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main differences from the Boeing 757 are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Since the cockpit of the Boeing 757 is identical to that of the Boeing 767, it looks oversized for the narrow-body fuselage of the 757. In comparison, the cockpit windows of the Tu-204 are smaller and look more natural.&lt;/li&gt;&#xA;&lt;li&gt;The top of the 757 fuselage slopes down over the full length of the vertical tail, whereas the downslope of the Tu-204 fuselage starts only at the rudder.&lt;/li&gt;&#xA;&lt;li&gt;To distinguish the Tu-204 from an Airbus A320, look at the wheels (four-wheel bogey on the Tupolev, two-wheel gear on the Airbus) or the APU exhaust, which in case of the Tupolev is a small tube sticking slightly out from the fuselage, while the Airbus has a metal-colored cover at the end of the fuselage.&lt;/li&gt;&#xA;&lt;li&gt;Another difference is the Tu-204's much longer fairing for the wing-fuselage intersection.&lt;/li&gt;&#xA;&lt;li&gt;Also, the winglet shape is quite different between those three types.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Tu-334&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Tu-334 is a shortened Tu-204 with fuselage-mounted engines. Only two have been built, so the chances to spot it are remote. The new location of the engines allows it to use a very short landing gear, and the shortened fuselage gives it a rather stubby, unique appearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HtfBr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HtfBr.jpg&quot; alt=&quot;Tupolev Tu-334&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar airplanes are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Short versions of the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-9&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-9&lt;/a&gt; like the DC-9-10 or the &lt;a href=&quot;http://www.planespotters.net/Aviation_Photos/search.php?tag=McDonnell%20Douglas%20DC-9-10&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-9-15&lt;/a&gt;; here the low bypass ratio of the DC-9 engines results in much smaller intakes and longer engine nacelles. Also, the fuselage of the DC-9 is more pointed ahead of the cockpit. The cockpit windows of the DC-9 have a separate window above the regular row of windows for better visibility in steep turns, which is missing in the Tu-334.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Comac_ARJ21&quot; rel=&quot;nofollow noreferrer&quot;&gt;Comac/Avic ARJ-21&lt;/a&gt;, a Chinese development which is based on the DC-9 fuselage, but has a modern, Antonov-developed wing and high-bypass-ratio engines. Here the upper cockpit windows are missing, so the best way to tell the Tu-334 apart from the ARJ-21 is again the more pointed fuselage nose of the ARJ-21, the bigger fairing of the ARJ-21's wing-fuselage intersection, the lower aspect ratio of the Tu-334 vertical tail and the rear end of the fuselage, which ends with a vertical edge in case of the ARJ-21.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-01-04T06:35:10.017" LastActivityDate="2019-01-04T06:35:10.017" CommentCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="17724" PostTypeId="1" AcceptedAnswerId="18724" CreationDate="2015-08-08T14:44:58.223" Score="10" ViewCount="2265" Body="&lt;p&gt;The B737 has no cover on its landing gear, as may be seen in this picture. Doesn't this increase the air drag?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QP2xs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QP2xs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all other airliners have doors that close off the rubber of the wheels, for example this B787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aXRKo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aXRKo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why doesn't the B737 have a cover on its landing gear?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="6886" LastEditDate="2015-08-08T18:00:31.523" LastActivityDate="2015-08-08T18:00:31.523" Title="Why do some commercial aircraft have no landing gear cover?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;landing-gear&gt;&lt;boeing-737&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-10T19:23:53.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="18724" PostTypeId="2" ParentId="17724" CreationDate="2015-08-08T17:34:33.797" Score="13" Body="&lt;p&gt;Yes, it does increase drag.  Anything that is not smooth, where the air flow will be disturbed, will generate drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 was originally designed only for short haul and space is at a premium.  Adding doors and all the associated mechanisms adds complexity, weight, additional maintenance requirements and more possibilities for failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing have had many opportunities to add doors and have chosen not to; so they, and their customers, do not see the drag penalty as more expensive than the extra weight and maintenance.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-08-08T17:34:33.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18725" PostTypeId="1" CreationDate="2015-08-08T17:45:25.477" Score="10" ViewCount="1781" Body="&lt;p&gt;Ideally I'm looking for a screenshot with a bullet list of data. I started my search at &lt;a href=&quot;https://en.wikipedia.org/wiki/Head-up_display#History&quot;&gt;the obvious encyclopedic site&lt;/a&gt; and was surprised to learn that the earliest HUDs (on fighter jets) go all the way back to the 40's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what data did they display? Presumably it would be a limited set of data compared to today's standards, and I'm very interested in what was considered the most important data for a HUD. Especially, did they have that circular piper showing where your bullets would impact?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1696" LastEditDate="2018-04-14T04:05:53.470" LastActivityDate="2018-04-26T07:58:34.560" Title="What data did the earliest HUDs display (for fighter jets)?" Tags="&lt;aviation-history&gt;&lt;fighter&gt;&lt;jet&gt;&lt;hud&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18726" PostTypeId="2" ParentId="17676" CreationDate="2015-08-08T17:57:55.037" Score="7" Body="&lt;p&gt;As already noted, they  &lt;em&gt;can&lt;/em&gt; be, but are not, in order to reduce drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the horizontal stabilizers in present generation of aircrafts are smaller than their predecessors. This is a result of the advances in design the aircraft with the introduction of fly-by-wire systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal stabilizers are designed to give stability to the aircraft by giving a &lt;em&gt;negative&lt;/em&gt; pitching moment. The aircraft wing, in itself is unstable. As lift is generated, the wing pitches up, which increases the angle of attack, increasing lift. This process goes on till the wing stalls. The horizontal stabilizer is effectively a smaller wing located at the other side of the center of gravity at a longer distance, negating this pitch up moment of the main wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically the horizontal stabilizer produces a &lt;em&gt;positive lift&lt;/em&gt;, but a &lt;em&gt;negative pitching moment&lt;/em&gt;. The bigger the horizontal stabilizer is, more the lift and stability, but also the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to reduce the drag is to have a smaller horizontal stabilizer, but this reduces stability, requiring the pilot to continuously adjust the controls to fly the aircraft. However, the introduction of computer controlled controls (fly-by-wire systems) meant that the aircraft could be unstable, with the computer adjusting the controls continuously to achieve stable flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, the aircraft designed after 1990's mostly have fly-by-wire control systems with smaller horizontal stabilizers, resulting in less drag and decreased fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, compare the horizontal stabilizers of DC10 and MD11.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aGKMR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aGKMR.jpg&quot; alt=&quot;http://i.stack.imgur.com/aGKMR.jpg&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:MD11_AND_DC10_varig_comparison.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 757 Maya&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MD11 was based on DC10, with stretched fuselage and increased wingspan, however with a smaller tailplane. This was achieved using a (partially) computer controlled horizontal stabilizer. As can be seen from the image, the horizontal stabilizer in the MD11 was smaller than the DC10, though the aircraft was larger. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the reason for smaller horizontal stabilizers is to reduce weight and drag and this is achieved mainly through the use of computer controlled control surfaces. Because the smaller stabilizer &lt;a href=&quot;https://en.wikipedia.org/wiki/Relaxed_stability&quot; rel=&quot;nofollow noreferrer&quot;&gt;relaxes the stability&lt;/a&gt;, even though it might have enough control due to the longer moment arm:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Relaxed stability designs are not limited to military jets. The McDonnell Douglas MD-11 has a relaxed stability design which was implemented to save fuel. To ensure stability for safe flight, an LSAS (Longitudinal Stability Augmentation System) was introduced to compensate for the MD-11's rather short horizontal stabilizer and ensure that the aircraft would remain stable. However, there have been incidents in which the MD-11's relaxed stability caused an &quot;inflight upset.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="14897" LastEditDate="2017-10-15T00:35:25.627" LastActivityDate="2017-10-15T00:35:25.627" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18727" PostTypeId="1" AcceptedAnswerId="18759" CreationDate="2015-08-08T18:21:10.713" Score="8" ViewCount="421" Body="&lt;p&gt;My textbook on air law says the following about Rule 41 of the Rules of the Air:-&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A person shall not, without permission, go onto a part of an aerodrome provided for the use of aircraft. This applies to any part that is not a public right of way.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems unlikely that you would have a public right of way across the manoeuvring area or apron of an aerodrome. How common is this?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-08-11T16:10:00.043" Title="When might an aerodrome contain a public right of way?" Tags="&lt;caa-uk-regulations&gt;&lt;rules-of-the-air&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18728" PostTypeId="2" ParentId="18727" CreationDate="2015-08-08T19:12:44.943" Score="5" Body="&lt;p&gt;My local aerodrome has a café underneath the control tower. To get to it, you have to go air-side and cross the main taxiway. There is no control on this - absolutely anybody can park up and walk over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not strictly a public right of way, but I'm sure one exists &lt;em&gt;somewhere&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that said, I think you may be reading a little to much into it - the primary thing to take from that paragraph is that the Air Navigation Order can not override a public right of way.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-08-08T19:12:44.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18729" PostTypeId="2" ParentId="17706" CreationDate="2015-08-08T21:11:11.357" Score="15" Body="&lt;p&gt;Thrust is air mass flow multiplied by the speed difference between flight and nozzle speed of the engine. To increase thrust, subsonic engines try to maximize mass flow (by increasing the bypass ratio) while supersonic engines rely more on increasing the nozzle speed (by using afterburners).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The core engines do not differ much - after all, the intake will make sure that air reaches the engine &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;at a speed of Mach 0.4 to 0.5&lt;/a&gt;, regardless of flight speed. The main difference is in their bypass ratio. The slower the design speed, the bigger the bypass ratio may become. At very low speed, the ungeared, shrouded fan is exchanged for a geared, free spinning propeller, in other words, the jet changes to a turboprop. The intake and nozzle, however, are very different indeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The optimum bypass ratio changes continuously, but since the drag coefficient drops after crossing Mach 1, airplanes are either designed for a maximum Mach number of 0.9 or less, or 1.6 and above. The corresponding bypass ratios today are up to 12 for subsonic engines, and less than 1 for supersonic engines. This produces a sharp boundary at the speed of sound, and many military engines designed for supersonic flight lost their afterburners and were fitted with a big fan to become the engines for subsonic transport aircraft. Examples are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney J57&lt;/a&gt; turbojet (installed in the F-100 and F-102 fighters, among others) became the JT-3D turbofan which powered the Boeing 707 or the DC-8.&lt;/li&gt;&#xA;&lt;li&gt;The core of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_F110&quot; rel=&quot;noreferrer&quot;&gt;General Electric F110&lt;/a&gt; (installed in the F-15 and F-16 fighters, among others) became the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;noreferrer&quot;&gt;CFM-56&lt;/a&gt; turbofan which is used in the Boeing 737 or the Airbus A320.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The differences between sub- and supersonic engines grow bigger the more you move away from their core. High-pressure compressor, combustion chamber and high pressure turbine look and work the same, but the low pressure compressor of subsonic engines swallows a lot more air and has a much bigger diameter. Supersonic engines in turn mostly have an afterburner. The biggest difference, however, are the intakes (large pitot intake with &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;blunt lips&lt;/a&gt; for subsonic aircraft versus adjustable &lt;a href=&quot;https://aviation.stackexchange.com/questions/13096/what-are-the-merits-of-an-inlet-cone-spike-centerbody-vs-a-2d-inlet/13109#13109&quot;&gt;spike or ramp intakes&lt;/a&gt; for supersonic flight) and the nozzle (fixed for subsonic flight versus a complex, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use&quot;&gt;adjustable convergent-divergent nozzle&lt;/a&gt; for supersonic flight). This is due to the very different air speeds and the much higher exit velocities required for supersonic flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-08-08T21:17:25.027" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18730" PostTypeId="1" AcceptedAnswerId="18739" CreationDate="2015-08-08T23:52:15.530" Score="12" ViewCount="1917" Body="&lt;p&gt;Peter Kampf points out in &lt;a href=&quot;https://aviation.stackexchange.com/a/17721/3825&quot;&gt;his answer on IDing Tupolevs&lt;/a&gt; that the Russian transport aircraft designs tend to be quite aerodynamically refined, in some ways better than their Western counterparts on that front.  What kept them from matching the West when it came to fuel efficiency then?  Was it purely a matter of the Russian need to build sturdy aircraft to withstand their rough strips in the middle of Siberia?  Or were there other factors, such as engine technology, in play?  And have the Russians &quot;caught up to us&quot; regarding aircraft fuel economy, or are they still trying to get the hang of building fuel-sipping airplanes?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-26T07:39:56.427" Title="What keeps Russian airliners from being as fuel efficient as their Western counterparts?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18731" PostTypeId="1" AcceptedAnswerId="18732" CreationDate="2015-08-09T00:26:59.433" Score="16" ViewCount="2043" Body="&lt;p&gt;I got checked out in the G1000 172 at my flight school just so I could schedule to fly when the two steam gauge 172s were booked. I'm very impressed by the G1000, but I can't wear sunglasses when I fly the NAVIII. This is with the avionics dial on the lighting panel turned all the way up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone else have this problem? Is it my sunglasses? &lt;/p&gt;&#xA;" OwnerUserId="9418" LastEditorUserId="39" LastEditDate="2015-08-13T19:09:18.973" LastActivityDate="2015-08-13T19:09:18.973" Title="Why is it hard to see G1000 with sunglasses?" Tags="&lt;avionics&gt;&lt;glass-cockpit&gt;&lt;g1000&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18732" PostTypeId="2" ParentId="18731" CreationDate="2015-08-09T01:02:56.803" Score="25" Body="&lt;p&gt;The screens are LCDs, which have a polarized filter layer over them. That layer is usually placed at a 45° so they are misaligned with your polarized sunglasses which are aligned vertically. You can confirm this is the problem by turning your sunglasses at different angles and see if the screen changes.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2015-08-12T20:58:19.680" LastActivityDate="2015-08-12T20:58:19.680" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="18733" PostTypeId="2" ParentId="16994" CreationDate="2015-08-09T01:53:17.070" Score="2" Body="&lt;p&gt;The fatigue life of helicopter dynamic components is determined by the manufacturer based on the number of hours flown and as such, varies from helicopter to helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, life of the dynamic components are less than that of the helicopter structure. The life of the dynamic components depend on the fatigue loads (the magnitude and load spectrum) and the materials used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the same helicopter involved in more demanding operations (civil vs. military) will have less life. Actually, during development, the fatigue life is determined in number of cycles, which is then converted to flying hours based on the expected flying pattern. Also, the materials used make a difference, with composite materials having better fatigue resistance compared to metallic blades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The life of the UH1 MRB (Main rotor Blade), for example is around 2500 hours. For UH60 MRBs, similar values have been quoted for metallic blades. However, Studies by MBB (Now part of Eurocopter) indicate that the composite blades under normal loading have a fatigue life of around 4000 hrs (&lt;em&gt;AGARD conference Proceedings No. 297, Helicopter Fatigue Life Assessment&lt;/em&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The life of other dynamic components, e.g. pitch horn, pitch link etc. are usually around 1000 hours. However, with little data available in public domain for helicopters under service, it is hard to say with any certainty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be kept in mind, however that these values are only indicative as all dynamic components are periodically checked using NDT methods and decision on their continued service is solely based on the results of these tests. For example, any damage to the bearing in the pitch links will result in their replacement. Also, the development of Health Usage Monitoring Systems (HUMS) means that most of the H/c manufacturers are moving away from a life based approach to a health based approach, resulting in variation in life of individual components.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-09T01:53:17.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18734" PostTypeId="1" CreationDate="2015-08-09T02:15:12.070" Score="2" ViewCount="394" Body="&lt;p&gt;I've often wondered if most passenger airliners have a CG envelope which would allow the CG of the airplane to be pushed outside the limits if enough passengers relocated to the front or back of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they do passengers might be surprised to know that if for some reason a lot of people got up and crammed into the back of the plane it might become uncontrollable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this is the case, the mental exercise could help illustrate how important an understanding of weight and balance is. It also highlights the importance of flight attendants as part of the air crew in their need to ultimately exert control over the crowd of passengers if the situation warrants it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a bit of background, I once wondered if Flight 93 during the September 11th attacks might have become uncontrollable because the CG shifted when passengers moved around the airplane. Although I once speculated that this could be the case, I am no longer speculating on the subject. I just want to mention that this is the scenario which made me wonder about the answer to the actual question. Since writing the original version of the question I learned about the CVR from Flight 93 and that it was intentionally flown into terrain by the hijackers.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-09T15:15:42.140" LastActivityDate="2015-08-09T15:15:42.140" Title="Could passengers on an airline flight create an out-of-CG situation by moving around the airplane?" Tags="&lt;airliner&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="10" ClosedDate="2015-08-09T06:28:47.530" ContentLicense="CC BY-SA 3.0" />
  <row Id="18735" PostTypeId="2" ParentId="18730" CreationDate="2015-08-09T02:23:34.683" Score="3" Body="&lt;p&gt;Every aircraft manufacturer has their philosophy in designing the aircraft, depending on their experiences (regulatory conditions, economy, availability of materials etc.) The Russians are the largest producers of crude oil and have no incentive to produce fuel efficient aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though the Russian aircrafts are aerodynamically equal to their western counterparts, their fuel gulping engines mean that they are as a whole, inefficient. This is because most of the fuel savings realized in aircraft are due to improvements in engine fuel consumption than due to aerodynamic improvements - 69% to 27% (&lt;em&gt;Lee, J. J., Lukachko, S. P., Waitz, I. A., and Schafer, A. (2001). &quot;Historical and future trends in&#xA;aircraft performance, cost and emissions.&quot; Annual Review Energy Environment, 26, 167-200.&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Improving the fuel efficiency of the engines requires not just a lot of research in aerodynamics, but also in materials (as the efficiency directly depends on the turbine temperature) and new manufacturing techniques. The Russians most probably had decided that it is not worth the cost and effort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this slowly changing as they try to export their aircraft to other countries in the world which demand better fuel efficiency. Still, they have a lot of catching up to do with their western counterparts.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="946" LastEditDate="2015-08-09T10:41:55.937" LastActivityDate="2015-08-09T10:41:55.937" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18736" PostTypeId="2" ParentId="18734" CreationDate="2015-08-09T03:03:55.477" Score="0" Body="&lt;p&gt;I was on a flight in an SWA B737 that was mostly empty and the flight attendants moved us all toward the front. They told us it was for balance reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think this was a factor on flight 93. The CVR recorded the hijackers discussing what to do about the passengers. The hijacker piloting the plane asked 'Is that it? Shall we finish it off?' Another hijacker responded, 'No. Not yet. When they all come, we finish it off.' Then a few seconds later when it sounds as if the passengers are getting through the cockpit door he asks, &quot;Is that it? I mean, shall we put it down?&quot; The other responded, &quot;Yes, put it in it, and pull it down.&quot; That's somewhat odd phrasing but those are translations from Arabic. It's clear that it was intentional.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-09T03:03:55.477" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18737" PostTypeId="1" AcceptedAnswerId="18738" CreationDate="2015-08-09T04:47:30.670" Score="0" ViewCount="1606" Body="&lt;p&gt;Our Country ministers helicopter didn't land because there is no helipad exist in my location, helicopter needs small place to land, then why Helicopter compulsory need helipad to land? &lt;/p&gt;&#xA;" OwnerUserId="9733" LastActivityDate="2015-08-09T05:14:15.410" Title="Why Helicopter compulsory need helipad to land?" Tags="&lt;helicopter&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ClosedDate="2015-08-09T06:00:30.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="18738" PostTypeId="2" ParentId="18737" CreationDate="2015-08-09T05:14:15.410" Score="6" Body="&lt;p&gt;Helicopters don't &lt;em&gt;need&lt;/em&gt; a helipad to land. It is simply safer landing in a helipad. I think the decision was taken in view of safety not to land because of the presence of the minister on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JOn8t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JOn8t.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, why did they come in helicopter if there was no helipad?&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-09T05:14:15.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18739" PostTypeId="2" ParentId="18730" CreationDate="2015-08-09T07:14:00.927" Score="18" Body="&lt;p&gt;The engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Russian engines were for decades behind the state of the art. One reason was manufacturing tolerances. I remember that we studied the &lt;a href=&quot;https://en.wikipedia.org/wiki/Progress_D-27&quot; rel=&quot;noreferrer&quot;&gt;Progress D-27 three-spool turboprop&lt;/a&gt; and found that just the cast casing could be made 250 kg lighter with Western tolerances. The Russian designers kept their tolerances wider to make sure that the minimum wall thickness would not be undercut.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, since Russian designers had less powerful computers available to them, they could rely less on CFD, so the turbo machinery was less refined. Improved engines explain maybe two thirds of the increase in fuel efficiency over the last 70 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is system redundancy. Russian engineers made sure the aircraft would still be operable after being maintained by a substandard maintenance crew. Especially the military designs were built with the goal of maintenance-free operation for several weeks. This thinking was also applied on the civilian side, since all Russian aircraft were designed with dual-use in mind. In case of war, all Aeroflot planes would become military transporters, and Aeroflot crews received most of their training on military aircraft. Why else would designs like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tu-134&quot; rel=&quot;noreferrer&quot;&gt;Tupolev Tu-134&lt;/a&gt; have a glazed nose?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o1TKD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o1TKD.jpg&quot; alt=&quot;Tu-134&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-134 (picture &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Izhavia_Tupolev_Tu-134.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-26T07:39:56.427" LastActivityDate="2016-01-26T07:39:56.427" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18740" PostTypeId="1" AcceptedAnswerId="18757" CreationDate="2015-08-09T11:25:39.520" Score="6" ViewCount="2495" Body="&lt;p&gt;Assuming control towers are essential for large airport operation, what is the &lt;strong&gt;minimum needed&lt;/strong&gt; equipment inside the standard control tower to support airport operation?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="97" LastEditDate="2015-08-09T23:11:40.653" LastActivityDate="2015-08-10T14:26:48.520" Title="What are the essential elements of a control tower?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18741" PostTypeId="2" ParentId="13066" CreationDate="2015-08-09T13:48:27.237" Score="2" Body="&lt;p&gt;If the aircraft has what is known as auto land, the auto pilot can land the airplane, so the pilot has that as an option. However, you can approach the runway in what is known as a forward slip. Using a lot of rudder, the tail will move to one side, this moves the nose to the opposite side, allowing the pilot to see forward, looking out the side window. The pilot also simultaneously uses opposite aileron, to counteract the turn, using the rudder would initiate. Once over the runway, at about 50 feet, the pilot would straighten the plane out, and begin the landing flare. He can then use the view of the the runway edge line, out his side window, to keep the plane aligned with the runway. A radar altimeter gives precise reading of how many feet he has to go, as he descends to the pavement. So, the pilot knows where he is. These things are practiced by flight crews in simulators twice a year.         &lt;/p&gt;&#xA;" OwnerUserId="9737" LastActivityDate="2015-08-09T13:48:27.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18742" PostTypeId="1" AcceptedAnswerId="18756" CreationDate="2015-08-09T15:34:30.127" Score="11" ViewCount="2815" Body="&lt;p&gt;I was looking over the wikipedia article for the 737NG when I came across this picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vv9AH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vv9AH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the operator of the jet has written their companies web address on the winglet.  Which seems like a waste, I'm already on their airplane, there's no need to sell me, it's not so much an ad as a reminder at that point...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, I couldn't help but think, when looking at it, that it would be somewhat clever if RedBull bought the rights to advertise on a 737NG and wrote something on that spot that said, &quot;Redbull gives you winglets&quot; (&lt;em&gt;rimshot&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sillines aside, there is a serious question here.  Generally speaking if there is a public surface that many many people will be forced to stare at for any length of time, then there is an advertisement there.  &lt;a href=&quot;http://obscuradigital.com/wp-content/uploads/IMG_5022.jpg&quot; rel=&quot;noreferrer&quot;&gt;Bus stops&lt;/a&gt;, &lt;a href=&quot;http://www.mvsd.org/wp-content/uploads/2014/01/2005-Billboard.jpg&quot; rel=&quot;noreferrer&quot;&gt;billboards&lt;/a&gt;, &lt;a href=&quot;http://2.bp.blogspot.com/-800T9zC5ZxE/UD_LxXI5ALI/AAAAAAAAyLk/BM00ZaC_HZ8/s1600/Pepsi+LiveNow+billboards+Times+square.jpg&quot; rel=&quot;noreferrer&quot;&gt;the sides of buildings&lt;/a&gt;, there are ads virtually everywhere.  Heck, commercial aviation equipment even has a few already with some of the jetways you see at airports:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wuLab.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wuLab.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are tens of thousands of people who see winglets every day (and even more who see winglets in travel pictures, blogs, etc), so why aren't advertisers taking advantage of the space and, further, why aren't airlines trying to sell the space in order to increase revenue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering if perhaps there are regulations that might make this difficult?  A good advertising spot will change images and products fairly frequently.  On a winglet that would necessitate either a new paint job or, perhaps, a new &lt;a href=&quot;https://en.wikipedia.org/wiki/Wrap_advertising&quot; rel=&quot;noreferrer&quot;&gt;vinyl wrap&lt;/a&gt; (like what is used in &lt;a href=&quot;http://3dprint.com/wp-content/uploads/2014/06/nas-1.jpg&quot; rel=&quot;noreferrer&quot;&gt;NASCAR&lt;/a&gt;.)  And I'm wondering if the regulations for commercial aircraft regarding how the winglets are painted would prohibit this sort of &quot;quick switch&quot; activity (are wraps even legal)?  Or perhaps there is a certification process for all new paint jobs that would make it so the amount spent to advertise would never match the increase in sales?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is it just that airlines have a sense of pride about their aircraft and respect their passengers enough to not bombard them with ads?  (&lt;em&gt;...yeah, I doubt it's this last one as well ;-)&lt;/em&gt; ).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit:  I did mark this one for FAA Regulations, but I feel EASA regulations should be similar enough to give some insight as well, so if you want to answer with those regs feel free.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-08-09T15:39:42.813" LastActivityDate="2015-08-11T13:47:50.013" Title="Why don't airliner winglets have consumer advertising on them?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;winglets&gt;&lt;paint&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18743" PostTypeId="2" ParentId="18742" CreationDate="2015-08-09T16:11:51.817" Score="7" Body="&lt;p&gt;I doubt the space is worth very much. The interior side of the winglet is really only visible to people on the plane and even most people on the plane can't see it well. You're only advertising to people with window seats at or behind the wing, plus a few people in non-window seats close to the wing who can see the winglet while looking almost perpendicularly out of the plane. That's only a few tens of people per flight who can see the ad. Multiply that by a few round-trips per day per plane and your ad is only reaching a couplefew hundred people a day. Given the cost of applying the ad to the winglets, I doubt that's economically viable, when you consider that a billboard ad can be seen by thousands of people an hour and is much cheaper to produce.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="878" LastEditDate="2015-08-10T09:19:07.873" LastActivityDate="2015-08-10T09:19:07.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18745" PostTypeId="1" CreationDate="2015-08-09T20:45:16.987" Score="9" ViewCount="2628" Body="&lt;p&gt;What are the different structural weight limitations that have to be considered when loading large aircraft? Is there a difference in complexity as to whether it's a passenger aircraft or a freighter being loaded?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think I know the answers, but it's precisely because I have to say &quot;I think&quot; rather than just &quot;I know&quot; that I'm asking the question. I'm hoping those here more technically oriented than I will be able to add to what I know.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="19" LastEditDate="2016-07-08T09:29:25.120" LastActivityDate="2016-07-08T09:29:25.120" Title="What are the different structural weight limitations that have to be considered when loading large aircraft?" Tags="&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18746" PostTypeId="2" ParentId="13042" CreationDate="2015-08-09T21:03:59.910" Score="6" Body="&lt;p&gt;We ran Olympus Gas turbines for fast power and speeds when I was in the Royal Navy. These happened to be the same turbines that Concord used when she was in service. We ran them on Marine Quality Diesel and had no problems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again may be its the - temps could be a real issue, and the fact you get more power from Higher octane fuels, with all the technology these days you would think their would be a cheaper alternative.&lt;/p&gt;&#xA;" OwnerUserId="9741" LastActivityDate="2015-08-09T21:03:59.910" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18747" PostTypeId="1" AcceptedAnswerId="20930" CreationDate="2015-08-09T22:35:53.017" Score="16" ViewCount="870" Body="&lt;p&gt;&lt;a href=&quot;http://www.denverpost.com/news/ci_28607221/delta-flight-from-boston-makes-emergency-landing-denver&quot; rel=&quot;noreferrer&quot;&gt;Delta 1889&lt;/a&gt; was forced to make an emergency landing last Friday (August 7th, 2015) after being battered by hail in a severe thunderstorm. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture in the news shows the two leading segments of the windshield have been ruined and will need to be replaced.  The nose cone of the jet has been caved in.  Zooming in suggests that the sheet metal ruptured where it made contact with whatever it behind it.  If that's the case I'm assuming it's too damaged to just have the dents pulled out and will also need to be replaced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond the obvious damage, what else will need to be looked at before the plane is able to resume normal operations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jl9kP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jl9kP.jpg&quot; alt=&quot;http://extras.mnginteractive.com/live/media/site36/2015/0808/20150808_124604_delta-flight.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1396" LastEditorUserId="946" LastEditDate="2015-08-10T08:05:24.083" LastActivityDate="2015-09-14T20:01:54.700" Title="What's the inspection/repair procedure following damage from severe hail?" Tags="&lt;weather&gt;&lt;airbus-a320&gt;&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18748" PostTypeId="1" AcceptedAnswerId="18752" CreationDate="2015-08-10T09:09:27.380" Score="7" ViewCount="4415" Body="&lt;ul&gt;&#xA;&lt;li&gt;Is it true that Pilots are not allowed to wear polarized sunglasses?&lt;/li&gt;&#xA;&lt;li&gt;What is the worst thing that can happen if wearing polarized&#xA;sunglasses in cockpit?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9690" LastEditorUserId="679" LastEditDate="2015-08-10T10:48:56.653" LastActivityDate="2016-02-21T21:42:48.143" Title="Is it allowed to wear polarized sunglasses in cockpit?" Tags="&lt;pilots&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-08-10T14:20:03.010" ContentLicense="CC BY-SA 3.0" />
  <row Id="18749" PostTypeId="1" AcceptedAnswerId="18750" CreationDate="2015-08-10T11:09:49.743" Score="0" ViewCount="3211" Body="&lt;p&gt;I wonder what are the elements below the wings (pointed by the black arrows in the image). I'm not referring to the sticks at the end of them, which I found them to be &amp;quot;static wicks&amp;quot;, used for static electricity discharge.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Nwwns.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nwwns.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-10T11:33:38.653" Title="What are these long tubes under the wings?" Tags="&lt;wing&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-08-10T11:59:19.160" ContentLicense="CC BY-SA 3.0" />
  <row Id="18750" PostTypeId="2" ParentId="18749" CreationDate="2015-08-10T11:33:38.653" Score="3" Body="&lt;p&gt;They are flap track fairings which contain the flap mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are called Küchemann carrots (also called anti-shock or Whitcomb body) and are used to reduce wave drag in transonic speeds. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-10T11:33:38.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18751" PostTypeId="2" ParentId="13066" CreationDate="2015-08-10T11:38:48.223" Score="0" Body="&lt;p&gt;Pilots tend to use the view out of the side windows in their peripheral vision to judge height above the runway, so provided you could see the approach lights at some point to know you are on the centre line, its not as bad as it sounds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are numerous examples in history of aircraft landing with oiled up, or iced up windscreens. Also it might be possible in some situations/aircraft to fly a curved approach then use the side windows in the final seconds of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My view is that the reason why the wind shield is opaque was probably a bigger risk to the aircraft than actually landing with it in that condition.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-10T11:38:48.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18752" PostTypeId="2" ParentId="18748" CreationDate="2015-08-10T12:32:57.520" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/sunglasses.pdf&quot; rel=&quot;nofollow&quot;&gt;This FAA document&lt;/a&gt; describes considerations for choosing sunglasses for pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the document concludes, that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Polarized sunglasses are not recommended&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I presume there is no rule that would explicitly forbid it. However there is always the “operate aircraft careless and reckless manner” paragraph and if you badly screwed up while wearing such sunglasses and there was grounded belief that some of the disadvantages of such sunglasses contributed to the incident, you could be charged with that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The document quotes following reasons why they are not recommended:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;may reduce or eliminate visibility of instruments with polarization-based anti-glare filters,&lt;/li&gt;&#xA;&lt;li&gt;may reduce or eliminate visibility of LCD instruments (LCDs emit polarized light by design),&lt;/li&gt;&#xA;&lt;li&gt;may interfere with visibility through an aircraft windscreen by enhancing striations in laminated materials,&lt;/li&gt;&#xA;&lt;li&gt;may mask the sparkle of light that reflects off shiny surfaces such as another aircraft’s wing or windscreen, which can reduce the time a pilot has to react in a “see-and-avoid” traffic situation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Even if your plane does not have any instruments with polarization filters and no issues with striations in laminated windshield, filtering reflections from other aircraft is definitely not what you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in most other situations, filtering reflections (from water, cars, metal roofs etc.) is desirable and is why polarized glasses exist, because reflections from close objects can be blinding. But in aircraft you are far from the sources of reflection, so the risk of blinding reflection is low, while the reflections can alert you to presence of other aircraft that might otherwise be hard to spot when looking towards the sun.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-02-21T21:42:48.143" LastActivityDate="2016-02-21T21:42:48.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18753" PostTypeId="1" AcceptedAnswerId="18755" CreationDate="2015-08-10T12:34:15.970" Score="26" ViewCount="2307" Body="&lt;p&gt;After a pushback I saw the operator of the pusback truck standing next to his truck and showing the pilots a &quot;thumbs up&quot; with his right hand. In his left hand he was holding something up. It looked like a key or some kind of cotter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could imagine that it is some kind of part that he could only have if he really is clear from the plane and didn't forget to disconnect something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I right? Is this some standard procedure? If so, what was he holding?&lt;/p&gt;&#xA;" OwnerUserId="744" LastEditorUserId="19" LastEditDate="2016-06-30T16:49:47.597" LastActivityDate="2016-06-30T16:49:47.597" Title="What item is a pushback operator holding up after pushback?" Tags="&lt;ground-operations&gt;&lt;pushback&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18754" PostTypeId="2" ParentId="18753" CreationDate="2015-08-10T12:40:56.033" Score="1" Body="&lt;p&gt;As you do not provide a photo, I have to speculate, but I do not see many options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The operator was probably holding the connector that allowed him/her to speak with the pilots, at the end of the pushback the connector is disconnected and the thumbs up is given to confirm the all clear to the pilots (no verbal communication is possible at this point).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-08-10T12:40:56.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18755" PostTypeId="2" ParentId="18753" CreationDate="2015-08-10T12:51:24.160" Score="27" Body="&lt;p&gt;It's a steering bypass pin which isolates the nose wheel steering and enables the tug to turn the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The operator holds it up so that the captain can see it to confirm that it has been removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pushback&quot;&gt;This Wikipedia article refers to it&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On some types, there may also be a &quot;downlock&quot; pin which prevents the nosewheel gear from retracting whilst the aircraft is on the ground.  In this case, the captain is looking for 2 pins being held up.  More often though, the ground lock pin(s) are removed before pushback and stowed onboard.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-08-10T14:17:11.377" LastActivityDate="2015-08-10T14:17:11.377" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18756" PostTypeId="2" ParentId="18742" CreationDate="2015-08-10T14:08:20.773" Score="12" Body="&lt;h3&gt;Why airlines don't put third-party ads on winglets&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;I would assume that a significant part of the answer is that it would look and feel cheap (i.e. not good for the airline's brand image.) They don't usually sell advertising elsewhere on their livery for much the same reason (though they do occasionally dedicate a livery to advertising some charity or some such thing, but that doesn't normally hurt their brand image.) On the other hand, putting the airline's brand image there can possibly help to improve it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you are already on the airline's flight, they'd be quite happy if you purchased more flights with them in the future and even more happy if you purchase the tickets directly from their website where they don't have to share the revenue with a travel agent. An additional benefit of mentioning the website is that many airlines now have on-board Wi-Fi and allow you to access their website from it even if you haven't paid for the Wi-Fi. As such, if they can get you thinking about their website and you happen to hop on it and book your next trip while cruising around at 30,000 feet, that's a win for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, while they do already have &lt;em&gt;you&lt;/em&gt; on board, they're well aware that lots of people post pictures taken while they were on a flight, especially pictures that include the wing (such as the one in the question.) Now your pictures are free (and usually positive) advertising for them.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Vinyl Wraps / Decals&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;As far as wraps are concerned, as far as I know, yes, they're legal and actually pretty common, even for the fuselage livery. My understanding is that lessors use them pretty frequently. They've also been used for temporary liveries like this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nktJy.jpg&quot; alt=&quot;Air New Zealand Hobbit Livery&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that several companies exist for the sole purpose of making aircraft wraps. A quick search found the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://adgraphics.graphics/products/aircraft-graphics/&quot; rel=&quot;noreferrer&quot;&gt;AdGraphics&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.aircraftwraps.com/home.html&quot; rel=&quot;noreferrer&quot;&gt;AircraftWraps&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.planevinyl.com/index.php&quot; rel=&quot;noreferrer&quot;&gt;Plane Vinyl&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that 3M &lt;a href=&quot;http://solutions.3m.com/wps/portal/3M/en_EU/3MGraphics/GraphicSolutions/Applications/VehicleGraphics/&quot; rel=&quot;noreferrer&quot;&gt;makes a lot of the materials used for the wraps&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also found &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch08.pdf&quot; rel=&quot;noreferrer&quot;&gt;an FAA document on aircraft coatings&lt;/a&gt; that talks about how to apply vinyl decals to aircraft (along with how to paint aircraft, etc.) From page 18:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Vinyl Film Decals&lt;/strong&gt;&lt;br&gt;&#xA;  To apply vinyl film decals, separate the paper backing from the plastic film. Remove any paper backing adhering to the adhesive by rubbing the area gently with a clean cloth saturated with water. Remove small pieces of remaining paper with masking tape.  &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Place vinyl film, adhesive side up, on a clean porous&#xA;  surface, such as wood or blotter paper.  &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Apply recommended activator to the adhesive in firm,&#xA;  even strokes to the adhesive side of decal.  &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Position the decal in the proper location, while&#xA;  adhesive is still tacky, with only one edge contacting&#xA;  the prepared surface.  &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Work a roller across the decal with overlapping strokes&#xA;  until all air bubbles are removed.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.signindustry.com/installation/articles/2008-07-01-Wrapping_airplanes_Aircraft_with_vinyl_graphics.php3&quot; rel=&quot;noreferrer&quot;&gt;This page from signindustry.com&lt;/a&gt; goes into more detail about how to apply vinyl decals to aircraft from a professional installer standpoint.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-11T13:47:50.013" LastActivityDate="2015-08-11T13:47:50.013" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="18757" PostTypeId="2" ParentId="18740" CreationDate="2015-08-10T14:26:48.520" Score="10" Body="&lt;p&gt;The theoretical bare minimum would be a light gun to give light signals to aircraft. A more generally acceptable minimum is a two-way radio to do radio communications with aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From there up other systems can be added. The list below gives some examples but is not exhaustive. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A telephone. Always useful when you want to get in contact with other parties on the ground (e.g. air traffic control centre) or other parties with you. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Meteorological instruments can provide current wind and visibility at the runway to the tower controller. This is not directly to support the Air Traffic Control function, but to provide information services to pilots. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airport lighting control: runway (and taxiway) lights are usually controllable from the tower. These systems can become quite complex on larger airports&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A display with a feed from an approach radar. This present the air traffic situation around the airport to the controller. Whilst on larger airports the approach controllers are usually not located in the tower itself, smaller airports often combine tower &amp;amp; approach control. Even when approach controllers are physically located elsewhere, the approach radar assists tower controllers as well in building a clear mental picture of the situation. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;An emergency button that makes the fire department jump to life.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Surface radar display. This presents the ground traffic situation to the controller. Often not found on small airports, but essential for efficient operations at busy airports, especially in low visibility.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;More radio's. To split tower control who do the runways and ground control who do the taxiing aircraft. Further divisions can be made. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A system that shows which runways are active, which are closed for use by the airport authority (e.g. for maintenance) &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Electronic flight strip system. The traditional paper strips are now often replaced by a digital equivalent. These E-strip system usually communicate with the whole flight data processing system, correlating strips to radar tracks. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Gate allocation system. It's always nice to now where those arriving aircraft should be directed once they are of the runway. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Gate video systems showing the situation at the gate. (to bust pilots that say they are ready for engine start / pushback whilst they are still loading cargo :-) )&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Departure management system. When you have a complex airport with multiple runways and a maze of taxiways, a DMAN may help to get aircraft airborne at the right time in the right sequence in the right direction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Arrival management system. With many aircraft arriving from all directions, headed for different terminal / gates it helps to have an AMAN to avoid overloading your Terminal Manoeuvring Area with incoming flights competing to be first.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Integration of the Surface radar, DMAN and Gate Allocation System with the lights control system. The level of integration varies. In the most extreme case pilots just have to follow the taxiways that light up green and stop at red stop bars. This avoids a lot of radio communications and confused pilots who didn't exactly remember a taxi clearing involving a dozen of taxiway letters. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-08-10T14:26:48.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18758" PostTypeId="1" AcceptedAnswerId="18774" CreationDate="2015-08-10T14:42:01.200" Score="5" ViewCount="2418" Body="&lt;p&gt;I have wondered this because the Trent 1000 engines are very similar to the Trent XWB engines on the 787. And if the A350 has better efficiency then why do so many airlines purchase the 787? &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="19" LastEditDate="2015-08-10T14:56:49.930" LastActivityDate="2015-08-10T22:52:40.530" Title="Is the A350 more efficent than the B787?" Tags="&lt;airliner&gt;&lt;boeing-787&gt;&lt;efficiency&gt;&lt;airbus-a350&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18759" PostTypeId="2" ParentId="18727" CreationDate="2015-08-10T14:47:34.550" Score="6" Body="&lt;p&gt;Obviously, putting publically-accessible areas within an airport's apron, taxiways, or runway environments is normally avoided as much as possible. However, sometimes space constraints don't give you another option. As Federico mentioned in a comment, &lt;a href=&quot;https://en.wikipedia.org/wiki/Gibraltar_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gibraltar International Airport&lt;/a&gt; is a famous example of this. A major city street runs right through the center of the runway:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ppco1.jpg&quot; alt=&quot;Gibraltar International Airport runway&quot;&gt;&lt;br&gt;&#xA;Gibraltar International Airport's runway with traffic on the street stopped for BA aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the runway runs the entire width of the peninsula. Obviously, they had to allow traffic to pass back and forth from one side to the other somehow, so one of the main city streets passes right through the middle of the runway and they just stop traffic on the street when the runway is in use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, another way to solve this problem is to do what &lt;a href=&quot;https://en.wikipedia.org/wiki/Nashville_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nashville International Airport&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Hartsfield%E2%80%93Jackson_Atlanta_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Atlanta Hartsfield-Jackson International Airport&lt;/a&gt; (and probably several others) have done and just send the road through a tunnel under the runway. I'm not sure how feasible that would be at Gibraltar's low elevation, though (i.e. might have water problems in the tunnel.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Vmsy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;Murfreesboro Road passing underneath Runway 2C/20C, Nashville International Airport&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/zm0wL.jpg&quot; alt=&quot;Runway 10/28, Atlanta Hartsfield-Jackson International Airport&quot;&gt;&lt;br&gt;&#xA;Interstate 285 passing underneath Runway 10/28, Atlanta Hartsfield-Jackson International Airport&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would expect that the main reason where you have situations like the one in Gibraltar is probably economics. For low-traffic airports, it's a lot easier to just stop the traffic than to build a big tunnel capable of supporting a large aircraft. For higher-traffic airports (like Nashville and, especially, Atlanta,) though, the tunnel is required as there are flights landing or taking off constantly (not to mention the security and safety risks of having cars driving around within the airport.) According to &lt;a href=&quot;https://en.wikipedia.org/wiki/Gibraltar_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;its Wikipedia page&lt;/a&gt;, Gibraltar International only has about 10 flights per day (3,564 total in 2013,) so it's manageable to just close the road when the runway is in use. I expect other airports with these sorts of crossings will be similarly low-traffic airports (or, at least, a low-traffic part of the airport.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-11T16:10:00.043" LastActivityDate="2015-08-11T16:10:00.043" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18760" PostTypeId="1" AcceptedAnswerId="18764" CreationDate="2015-08-10T15:47:50.080" Score="15" ViewCount="5784" Body="&lt;p&gt;Military aircraft usually display a serial number along with other insignia on the tail or body of the aircraft, &lt;a href=&quot;https://en.wikipedia.org/wiki/United_States_military_aircraft_serials&quot;&gt;as described here&lt;/a&gt;.  However military serial numbers are not the same as FAA tail numbers on civilian US aircraft, which begin with the letter &quot;N&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do military aircraft also have an &quot;N&quot; number, or do US military aircraft simply not have an &quot;N&quot; number?  &lt;/p&gt;&#xA;" OwnerUserId="2141" LastActivityDate="2017-05-22T19:53:41.037" Title="Do US military aircraft have tail numbers beginning with &quot;N&quot;?" Tags="&lt;military&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18761" PostTypeId="1" CreationDate="2015-08-10T15:56:17.810" Score="2" ViewCount="113" Body="&lt;p&gt;The B787 has these chevron-shaped teeth on the exhaust port of its engines to reduce noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6b/Toothed_exhaust_duct_covers_on_a_Boeing_787.jpg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6b/Toothed_exhaust_duct_covers_on_a_Boeing_787.jpg&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And according to the answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/119/with-the-upgrade-of-the-737-to-the-max-model-what-major-changes-are-incorporate&quot;&gt;this question&lt;/a&gt; they will be incorporated into the new B737's &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone explain how these work to reduce noise?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-10T15:56:17.810" Title="How do the chevrons on engine nacelles reduce noise?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;noise&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2015-08-10T16:21:14.773" ContentLicense="CC BY-SA 3.0" />
  <row Id="18762" PostTypeId="1" AcceptedAnswerId="19063" CreationDate="2015-08-10T16:25:34.957" Score="7" ViewCount="227" Body="&lt;p&gt;If I fly GA into Canada from the US or into the US from Canada, does having Global Entry give me any advantage? Can I taxi straight to the FBO or my tie down spot, or do I still have to taxi over to customs? Is there any ability to fly direct to a destination and not have to stop at a port of entry airport? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between Pre clearance and Global Entry? Can you get pre clearance without having Global Entry?&lt;/p&gt;&#xA;" OwnerUserId="4509" LastActivityDate="2015-08-20T02:06:37.183" Title="Does Global Entry give you any benefits when flying GA?" Tags="&lt;international&gt;&lt;pre-clearance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18763" PostTypeId="1" AcceptedAnswerId="18765" CreationDate="2015-08-10T16:45:48.807" Score="18" ViewCount="5638" Body="&lt;p&gt;I often see this particular shape for ram air inlets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here on an older 737&lt;br&gt;&#xA;&lt;a href=&quot;http://www.b737.org.uk/images/ramairinlet.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YshfG.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's stretched on the newer 737's but still the same basic shape&lt;br&gt;&#xA;&lt;a href=&quot;http://www.b737.org.uk/images/ramairinlet-ng.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JOWzZ.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A also see it a lot on cars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1979 Camaro Z28&#xA;&lt;a href=&quot;https://i264.photobucket.com/albums/ii162/earnhardtgm3/0811091712a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M3qK7.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lamborghini Countach&#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/0/06/Countach_Autostadt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GtGMB.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some aerodynamic advantage to this shape, and if so why?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="21582" LastEditDate="2017-05-03T19:19:08.367" LastActivityDate="2017-05-03T19:19:08.367" Title="Why do many ram air inlets have this shape?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18764" PostTypeId="2" ParentId="18760" CreationDate="2015-08-10T16:52:34.527" Score="11" Body="&lt;p&gt;The 'N' numbers you're referring to are &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_registration#United_States&quot;&gt;FAA registration numbers&lt;/a&gt;. The FARs (Federal Aviation Regulations) specifically mention registration as not being required for military aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8517c4b02d4f72e5f49c2c9c51562d37&amp;amp;mc=true&amp;amp;node=se14.1.47_13&amp;amp;rgn=div8&quot;&gt;14 CFR 47.3&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) No person may operate an aircraft that is eligible for registration under 49 U.S.C. 44101-44104, unless the aircraft—  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Has been registered by its owner;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Is carrying aboard the temporary authorization required by §47.31(c); or &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) &lt;strong&gt;Is an aircraft of the Armed Forces&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA issues these registrations in accordance with its responsibilities under the &lt;a href=&quot;https://en.wikipedia.org/wiki/Chicago_Convention_on_International_Civil_Aviation&quot;&gt;Chicago Convention on International Civil Aviation&lt;/a&gt;, which required (in &lt;a href=&quot;http://www.icao.int/safety/airnavigation/NationalityMarks/article20_doc7300_en.pdf&quot;&gt;Article 20&lt;/a&gt;) that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Every aircraft engaged in international air navigation shall bear its appropriate nationality and registration marks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As per the above-cited 14 CFR 47.3, though, the U.S. specifically requires that all eligible aircraft have registrations unless it's either a military aircraft or it has temporary authorization under 14 CFR 47.31(c).&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-10T20:52:41.757" LastActivityDate="2015-08-10T20:52:41.757" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18765" PostTypeId="2" ParentId="18763" CreationDate="2015-08-10T16:58:17.497" Score="16" Body="&lt;p&gt;Those are called NACA inlets or &lt;a href=&quot;https://en.wikipedia.org/wiki/NACA_duct&quot;&gt;NACA ducts&lt;/a&gt;. As wikipedia mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When properly implemented, a NACA duct allows air to flow into an internal duct, often for cooling purposes, with a minimal disturbance to the flow.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So yes, there is an aerodynamic advantage.&#xA;As for the &quot;why&quot;, if you're in the mood, you can have a detailed look at the &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1945/naca-acr-5i20.pdf&quot;&gt;original report&lt;/a&gt; (I'm not able to properly summarize it).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-08-10T16:58:17.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18766" PostTypeId="1" AcceptedAnswerId="18769" CreationDate="2015-08-10T17:04:54.813" Score="12" ViewCount="1969" Body="&lt;p&gt;&lt;a href=&quot;http://tfr.faa.gov/save_pages/detail_4_3621.html&quot; rel=&quot;noreferrer&quot;&gt;FDC Notam 4/3621&lt;/a&gt; creates a generic &quot;template&quot; TFR which sits on top of sporting events.  This one in Phonenix appears to sit right on one of the business ends of Phoenix Sky Harbor (PHX)  The Notam states that event operations are permitted with the appropriate waiver.  How do regularly scheduled airlines deal with such TFR's?  Are waivers obtained for scheduled inbound flights?  There does not seem to be verbage in the notam granting any exceptions for air carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nYfFE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nYfFE.png&quot; alt=&quot;TFR Visualization on Phoenix sectional showing TFR inside approaches into PHX&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="64" LastEditDate="2015-08-10T17:19:08.577" LastActivityDate="2015-08-10T19:27:12.597" Title="How do pilots and controllers deal with TFR's that lie directly on an approach?" Tags="&lt;airline-operations&gt;&lt;tfr&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18767" PostTypeId="2" ParentId="18727" CreationDate="2015-08-10T17:17:23.883" Score="7" Body="&lt;p&gt;Less busy than Gibraltar, but in the UK proper, Sumburgh in Shetland is an example of &quot;road crossing the runway&quot; on a relatively active airport - it even comes complete with level crossing gates, which are a startling thing to see on the road ahead when you know there's no railway!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X9XiI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X9XiI.jpg&quot; alt=&quot;Aircraft landing at Sumburgh, seen from the road&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8729" LastActivityDate="2015-08-10T17:17:23.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18768" PostTypeId="2" ParentId="18766" CreationDate="2015-08-10T17:36:03.313" Score="6" Body="&lt;p&gt;There is exemption language in FDC 4/3621 (note the underlined section in the screen grab below):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/B441W.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B441W.png&quot; alt=&quot;FDC 4/3621 from tfr.faa.gov&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;THE RESTRICTIONS DESCRIBED ABOVE DO NOT APPLY TO THOSE AIRCRAFT AUTHORIZED BY AND IN CONTACT WITH ATC FOR OPERATIONAL OR SAFETY OF FLIGHT PURPOSES  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Conducting an approach (instrument or visual) to an airport is an &quot;operational purpose&quot;, and as KPHX is in Class B airspace with an operating control tower any aircraft landing there will, by necessity, be in contact with ATC (or in violation of a bunch of other regulations).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ATC tells you to fly through the stadium TFR for your approach and landing you then meet the requirements of that exemption (&quot;authorized by and in contact with ATC&quot;, for the operational purpose of landing at Sky Harbor) &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that this was not always the case.  The earliest versions of the &quot;sporting events TFR&quot; did not include exemptions for aircraft in contact with ATC (&lt;a href=&quot;http://www-scf.usc.edu/~dgerard/history.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;that appeared in 2009&lt;/a&gt;, presumably because the FAA realized that requiring every airline flying into Phoenix to get a waiver for baseball season was an administrative nightmare for all concerned).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-10T17:36:03.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18769" PostTypeId="2" ParentId="18766" CreationDate="2015-08-10T17:36:57.650" Score="7" Body="&lt;p&gt;The NOTAM itself answers your question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;THE RESTRICTIONS DESCRIBED ABOVE DO NOT APPLY TO THOSE AIRCRAFT&#xA;  AUTHORIZED BY AND IN CONTACT WITH ATC FOR OPERATIONAL OR SAFETY OF&#xA;  FLIGHT PURPOSES, DEPARTMENT OF DEFENSE, LAW ENFORCEMENT, AND AIR&#xA;  AMBULANCE FLIGHT OPERATIONS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As long as the pilot is in contact with Air Traffic Control and has been cleared through the TFR, they can safely fly though the airspace.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-08-10T17:36:57.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18770" PostTypeId="2" ParentId="18766" CreationDate="2015-08-10T18:28:27.093" Score="1" Body="&lt;p&gt;The City of Seattle has the major Baseball and Football stadiums directly in the approach path for &lt;a href=&quot;https://skyvector.com/?ll=47.573190458491474,-122.29087829235318&amp;amp;chart=301&amp;amp;zoom=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing Field&lt;/a&gt;.&lt;a href=&quot;https://i.stack.imgur.com/K367N.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K367N.jpg&quot; alt=&quot;KBFI Stadium TFR&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TFR covers both KBFI's Class D and KSEA's Class B airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The text of the NOTAM specifically says that when talking to controllers, you can go through it.  That is not only for the purpose of approach the airports.  You can also request a transition, and so long as you're talking to ATC and following their directions, you can go right through the TFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I &lt;em&gt;believe&lt;/em&gt; I've even observed sight-seeing flights circling the stadium, rather than transitioning the space.  Presumably they were talking to ATC and got permission.   The point is, depending on the text of a TFR, the restriction may not be inviolable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some TFRs, such as a Presidential TFR during arrival and departure procedures will be rock-solid.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-08-10T19:27:12.597" LastActivityDate="2015-08-10T19:27:12.597" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18771" PostTypeId="1" AcceptedAnswerId="18772" CreationDate="2015-08-10T19:58:04.800" Score="9" ViewCount="6450" Body="&lt;p&gt;Under what circumstances is an FAA accident report required?  For example, if two planes are pushing back from a terminal and their wings collide is an accident report always required or does it depend upon damage done to the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="9751" LastEditorUserId="64" LastEditDate="2015-08-10T20:36:39.013" LastActivityDate="2015-08-10T20:36:39.013" Title="Under what circumstances is an FAA accident report required?" Tags="&lt;accidents&gt;&lt;faa&gt;&lt;ntsb&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18772" PostTypeId="2" ParentId="18771" CreationDate="2015-08-10T20:34:53.053" Score="12" Body="&lt;p&gt;Generally you do not notify the FAA, you notify the NTSB (the relevant regulations are in &lt;strong&gt;49&lt;/strong&gt;CFR, specifically &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;rgn=div5;view=text;node=49:7.1.4.1.12;idno=49;cc=ecfr&quot;&gt;49CFR830&lt;/a&gt;).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you notify the FAA they will contact the NTSB, because the NTSB is the agency charged with investigating aircraft accidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you crash in a cornfield somewhere and notify the NTSB they will probably ask the nearest FSDO to send an investigation team (unless you're a major airline or a fairly high-profile incident).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So ultimately it doesn't much matter which agency you call, but you &lt;em&gt;should&lt;/em&gt; be calling the NTSB.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;With the administrative stuff out of the way, the reporting requirements are also in that same section of 49CFR. Basically they say:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are required to notify the NTSB &lt;em&gt;&quot;immediately, and by the most expeditious means available&quot;&lt;/em&gt; of any aircraft accident, which is defined as:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;…an occurrence associated with the operation of an aircraft which takes place between the time any person boards the aircraft with the intention of flight and all such persons have disembarked, and in which any person suffers death or serious injury, or in which the aircraft receives substantial damage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You are also required to notify the NTSB (again, &lt;em&gt;&quot;immediately, and by the most expeditious means available&quot;&lt;/em&gt; of any incident (something that's not an accident as defined above) which meets the following criteria:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Flight control system malfunction or failure;&lt;/li&gt;&#xA;  &lt;li&gt;Inability of any required flight crewmember to perform normal flight duties as a result of injury or illness;&lt;/li&gt;&#xA;  &lt;li&gt;Failure of any internal turbine engine component that results in the escape of debris other than out the exhaust path;&lt;/li&gt;&#xA;  &lt;li&gt;In-flight fire;&lt;/li&gt;&#xA;  &lt;li&gt;Aircraft collision in flight;&lt;/li&gt;&#xA;  &lt;li&gt;Damage to property, other than the aircraft, estimated to exceed $25,000 for repair (including materials and labor) or fair market value in the event of total loss, whichever is less.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;em&gt;Specific requirements for aircraft with a takeoff weight above 12,500 pounds&lt;/em&gt;&lt;/li&gt;&#xA;  &lt;li&gt;Release of all or a portion of a propeller blade from an aircraft, excluding release caused solely by ground contact;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;em&gt;Specific requirements for &quot;glass cockpit&quot; displays.&lt;/em&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;em&gt;Specific requirements for TCAS advisories&lt;/em&gt;.&lt;/li&gt;&#xA;  &lt;li&gt;Damage to helicopter tail or main rotor blades, including ground damage, that requires major repair or replacement of the blade(s);&lt;/li&gt;&#xA;  &lt;li&gt;&lt;em&gt;Specific requirements for air carrier blunders like landing on the wrong runway&lt;/em&gt;.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&quot;Immediately and by the most expeditious means available&quot; basically means pick up the telephone and call them: They don't want you dispatching a letter via Pony Express that's going to take a week to get to the NTSB's headquarters while the aircraft is sitting in a field exposed to the elements with evidence literally washing away in the rain.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-10T20:34:53.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18773" PostTypeId="2" ParentId="18727" CreationDate="2015-08-10T22:47:43.900" Score="0" Body="&lt;p&gt;Quite a number of airports in Switzerland have roads cross airports. This one is Alpnach Airport&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CpI3K.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CpI3K.png&quot; alt=&quot;Alpnach Airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-10T22:47:43.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18774" PostTypeId="2" ParentId="18758" CreationDate="2015-08-10T22:52:40.530" Score="8" Body="&lt;p&gt;The answer as to why companies seem to be favoring the 787 over the A350 is in several parts, none having very much to do with efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, a grand total of just 6 A350 XWBs have been built. The A350 is just ramping up production this year, while the 787 has been in production about 5 years now. The 787's teething problems have spurred some interest in its competitor, but as the first composite airliner to start accepting orders, the Dreamliner has a distinct first-mover advantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, Airbus has seen some production problems in its larger airliners, which tends to make airlines nervous. The A380 saw cancellations totaling over $10 billion in lost revenue primarily due to its inability to make them fast enough, causing Airbus to indefinitely delay production of freight variants that major shipping companies were waiting for. Smaller, older production lines have been doing better but the A380 line is still taking up a lot of Airbus's resources that could be spent making 350s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third is simple cost. A 787-8's base price is about \$225 million. An A350 starts at about \$270 million. \$45 million a plane is nothing to sneeze at; it means you can have 6 Dreamliners for the cost of 5 A350s, and the major airlines are buying 40-50 of these planes each so the savings is considerable.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-10T22:52:40.530" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18775" PostTypeId="1" CreationDate="2015-08-11T01:04:19.633" Score="21" ViewCount="8275" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/17693/do-fighter-jets-have-forward-looking-radar-warnings-for-missiles-and-when-was-t/17696?noredirect=1#comment42945_17696&quot;&gt;my related question&lt;/a&gt;, it seems fighter jets do not usually track missiles by radar. Instead, they have a system that warns of radar lock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what about infrared missiles (heat-seeking missiles)? Flares are a countermeasure to these, so how does the jet know when one is incoming?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would be pretty surprised if such a system didn't exist. I want to know more about that system and when it was first implemented.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1696" LastEditDate="2018-04-14T04:05:34.330" LastActivityDate="2018-04-14T04:05:34.330" Title="How do combat jets know when to launch flares to counter IR missiles?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;missiles&gt;&lt;missile-lock&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18776" PostTypeId="2" ParentId="18775" CreationDate="2015-08-11T02:15:36.357" Score="13" Body="&lt;p&gt;Before continuing, much of the how's and why's of IRCM are going to be either speculation, or classified.  Nations will not freely discuss their actual methods of defeating opposing nation's IR capabilities.  Therefore, actual answers will be difficult to give.  However, here is an excerpt from Wikipedia regarding a specific missile warning system that may be found on military aircraft.  This represents one possible method used for &lt;em&gt;certain&lt;/em&gt; types of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The AN/AAR-47 Missile Warning System is a Missile Approach Warning system &lt;strong&gt;used on slow moving aircraft such as helicopters and military transport aircraft&lt;/strong&gt; to notify the pilot of threats and to trigger the aircraft's countermeasures systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AN/AAR-47 passively detects missiles by their infrared signature, and uses algorithms to differentiate between incoming missiles and false alarms.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/AN/AAR-47_Missile_Approach_Warning_System&quot;&gt;https://en.wikipedia.org/wiki/AN/AAR-47_Missile_Approach_Warning_System&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="100" LastEditDate="2015-08-11T09:56:09.790" LastActivityDate="2015-08-11T09:56:09.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18777" PostTypeId="2" ParentId="18775" CreationDate="2015-08-11T03:38:19.930" Score="20" Body="&lt;p&gt;Actually most aircraft don't actively know when a missile is being fired at them. I have worked on helicopters and fighters that deploy counter measures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first is an IR jammer which we call a disco ball. It is made up of mirrors at different angles that resemble a disco ball. It radiates an IR signal at different angles to confuse the missiles.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flares or chaff are fired periodically in known hot spots. This creates heat signatures similar to the engines and confuses the missiles.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are active systems but they don't work well. I have seen a helicopter in testing suspended from a wire with countermeasures turned on. A missile was fired and the countermeasures didn't even get deployed. This is why they usually keep firing the flares or chaff in known hot spots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope that helps.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastEditorUserId="595" LastEditDate="2015-08-11T13:16:54.913" LastActivityDate="2015-08-11T13:16:54.913" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="18778" PostTypeId="1" CreationDate="2015-08-11T05:31:31.663" Score="4" ViewCount="199" Body="&lt;p&gt;So I've been reading technical aviation books and I come across a lot words I want to learn to say correctly but unlike simple words which I just look up in an audio Oxford dictionary I can't think of where online I can find audio pronunciations of aviation words. Any suggestions? &lt;/p&gt;&#xA;" OwnerUserId="870" LastActivityDate="2015-08-11T19:55:52.473" Title="Is there a tool to learn to pronounce aviation jargon accurately?" Tags="&lt;books&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18779" PostTypeId="2" ParentId="18775" CreationDate="2015-08-11T11:03:04.020" Score="7" Body="&lt;p&gt;The infrared missiles are usually detected using a Missile Approach Warning Sensor (MAWS). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Missile Approach Warning Systems are passive detectors, usually detecting either the infrared or ultraviolet rays emitted by the incoming missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The infrared based systems detect the infrared waves emitted by the missile. The ultraviolet based systems detect the ultraviolet rays emitted by the missile's rocket motors and are more suitable for detecting missiles with solid rocket motors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example for the infrared based detector is the US-Israel PAWS, while the Swedish MAW-300 uses an ultraviolet detector. Some systems like the MWS-20 uses Doppler Radar to detect the missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All these systems have their advantages and disadvantages, and in relation to your previous question, give a 360 degree coverage based on the location of their installation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most of the aircraft, these detection systems, along with the Radar Warning Receiver, which detect the Radar based missiles are integrated into the Self Protection System(SPS), which determines the threat level of the incoming missile and responds accordingly by firing chaff and flares. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-11T11:03:04.020" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="18780" PostTypeId="1" AcceptedAnswerId="18781" CreationDate="2015-08-11T12:55:12.740" Score="21" ViewCount="12415" Body="&lt;p&gt;In my city, most of, if not all of the fire-trucks that serve city emergencies are &lt;strong&gt;red&lt;/strong&gt;, just like this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FOGuI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FOGuI.jpg&quot; alt=&quot;Regular Fire-truck&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But every time that I see an airport emergency that requires the fire-fighters, I see this kind of truck:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EU59P.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EU59P.jpg&quot; alt=&quot;Airport Fire-truck&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a reason why the airport trucks are yellow-green and not red?&lt;/p&gt;&#xA;" OwnerUserId="1700" LastActivityDate="2017-11-13T01:08:03.147" Title="Why are airport firetrucks painted yellow green?" Tags="&lt;emergency&gt;&lt;airport&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18781" PostTypeId="2" ParentId="18780" CreationDate="2015-08-11T13:10:27.140" Score="28" Body="&lt;p&gt;Because yellow/green has been shown to be more visible than red, especially in low light conditions.  Yellow/green is also more easily identified by people with colour blindness and other visual disorders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the same reason that safety vests are yellow/green.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.apa.org/action/resources/research-in-action/lime.aspx&quot;&gt;This article gives some good references.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-08-11T13:10:27.140" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="18782" PostTypeId="1" AcceptedAnswerId="18810" CreationDate="2015-08-11T14:11:02.970" Score="-1" ViewCount="1019" Body="&lt;p&gt;On very poor visibility, the pilot approaches under ILS procedure.&#xA;Usually they are requested to call the TOWER, when visual with the runway, to receive the landing clearance. However, on ILS Cat 2 or 3, it happens quite close to the runway, then the pilots will not have enough time, to switch on the Tower´s frequency to receive the clearance. Then the Approach Control may say: &quot;The tower clears you to land.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Does the tower CLEAR the landing, or only inform the runway is clear? &lt;/li&gt;&#xA;&lt;li&gt;Is it the pilot´s decision to land or not? &lt;/li&gt;&#xA;&lt;li&gt;Where can I read this specific document or phraseology?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9458" LastEditorUserId="19" LastEditDate="2016-07-08T09:31:08.620" LastActivityDate="2016-07-08T09:31:08.620" Title="What are the procedures and responsibilities concering landing clearances on ILS Cat 2 or 3?" Tags="&lt;landing&gt;&lt;instrument-procedures&gt;&lt;ils&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18783" PostTypeId="1" AcceptedAnswerId="18786" CreationDate="2015-08-11T14:24:40.360" Score="13" ViewCount="1788" Body="&lt;p&gt;Let's say, hypothetically, that you enter the pattern for a small, non-towered airport (my local one, &lt;a href=&quot;https://en.wikipedia.org/wiki/Downtown_Airport_(Missouri)&quot; rel=&quot;nofollow&quot;&gt;3DW&lt;/a&gt;, may be a good example.)  But as you get into the pattern you find out that the runway is occupied by another craft and, for whatever reason the runway will probably be occupied for another 20 minutes, much longer than it will take you to complete the pattern.  So you'll have to delay landing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you've already entered the pattern, so what should you do?  Is there a standard holding pattern for small airports that incorporates parts of the pattern (maybe some little loop where the base leg and downwind meet)?  Or do you just fly away form the airport a bit and make up your own holding pattern?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-08-12T12:49:19.753" LastActivityDate="2015-08-12T23:37:25.407" Title="How do you hold at a non-towered airport?" Tags="&lt;landing&gt;&lt;traffic-pattern&gt;&lt;holding&gt;" AnswerCount="5" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18784" PostTypeId="2" ParentId="18763" CreationDate="2015-08-11T14:28:27.313" Score="8" Body="&lt;p&gt;This specific inlet type is called a &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/National_Advisory_Committee_for_Aeronautics&quot; rel=&quot;noreferrer&quot;&gt;NACA&lt;/a&gt; inlet&quot;, &lt;a href=&quot;http://www.flyingmag.com/scoop-naca-scoop&quot; rel=&quot;noreferrer&quot;&gt;&quot;NACA scoop&quot;&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/NACA_duct&quot; rel=&quot;noreferrer&quot;&gt;&quot;NACA duct&quot;&lt;/a&gt;, since it had been invented by &lt;a href=&quot;https://en.wikipedia.org/wiki/Francis_Rogallo&quot; rel=&quot;noreferrer&quot;&gt;Francis Melvin Rogallo&lt;/a&gt; at &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1941/naca-report-713.pdf&quot; rel=&quot;noreferrer&quot;&gt;NACA in 1941 (PDF)&lt;/a&gt; and refined by scientists at &lt;a href=&quot;http://www.nasa.gov/centers/ames/home/index.html&quot; rel=&quot;noreferrer&quot;&gt;NACA (now NASA) Ames&lt;/a&gt;. Its main advantage is its simplicity: It just needs a properly shaped cutout in the skin and a rounded rear edge, whereas the airscoops it replaces need carefully shaped contours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The working principle is quite similar to that of a delta wing, only in this case the actual wing is missing, and is surrounded by sheet metal. But like on the swept leading edge of a delta wing, the swept left and right edges create a vortex which is swallowed by the actual intake at the rear of the cutout. This helps to create a lot of flow for the given area, even though efficiency is below that of a well-shaped airscoop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The moveable flap in the middle of the cutout is for deflecting some of the air if less than maximum airflow is desired. This item is easy to manufacture, but reduces the efficiency of this type of inlet further.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-08-11T14:28:27.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18785" PostTypeId="2" ParentId="18782" CreationDate="2015-08-11T14:34:05.643" Score="2" Body="&lt;p&gt;You are typically (I hesitate to say always, as I have no evidence for this) cleared to land, and are not requested to call visual with the runway. This is because, as you state, there is not time to call visual with the runway and request clearance: by the time you see the runway you could be at 370m (Cat II) or 0-300m (Cat III) from the end of the runway and less than 200 feet above it: there is not necessarily enough time to call the tower and receive clearance before you would have to miss the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, for a (theoretical, as I do not believe any exist) cat IIIc approach, you do not necessarily even see the runway before your wheels touch it, as there is no required Runway Visual Range specified. In such a case, it would not be possible to call the runway visual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the tower clears you &quot;to land&quot;, you have permission to go ahead and put your wheels on the runway. There's no ambiguity in the clearance, if you're cleared to land then you're cleared to land. Of course, that never obliges you to land, you're still the pilot in command.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-08-11T15:02:18.547" LastActivityDate="2015-08-11T15:02:18.547" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18786" PostTypeId="2" ParentId="18783" CreationDate="2015-08-11T15:36:46.997" Score="8" Body="&lt;p&gt;There's no &quot;standard holding pattern&quot; at any airport, towered or not. If the runway is occupied or temporarily closed for some reason, you might was well leave the traffic pattern and go putt around for a while someplace where there are fewer aircraft. At a towered airport, the controller will likely tell you what to do - but again, you can make both his life and yours easier by just leaving the pattern and going somewhere else until the situation is resolved.&lt;/p&gt;&#xA;" OwnerUserId="9761" LastActivityDate="2015-08-11T15:36:46.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18787" PostTypeId="2" ParentId="18783" CreationDate="2015-08-11T15:49:35.543" Score="2" Body="&lt;p&gt;As far as I know, there's no such thing as a &quot;standard holding pattern&quot; for uncontrolled fields, though I suppose Center might put you in some holding pattern if you're IFR. For VFR, though, if I found out that the runway was going to be unavailable for 20 minutes (and was reasonably likely to be open again after that time and I had plenty of fuel,) I'd just leave the pattern and fly a few miles away from the airport for a while. I'd then continue to monitor the CTAF to hear what's going on and if/when the runway is open again. If it seemed like it was going to be a while, I'd just go land at another nearby airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the time, however, delays at uncontrolled fields will be brief (i.e. someone is back-taxiing, is taking off, is on final, or just landed) and you can just either make a 360 or a 270 degree turn to base (to the opposite direction as normal) to waste time until the runway is clear. Normally, this won't be more than a couple of minutes at a time. Normal checks, configuration changes, etc. should be made before entering the runway, so you won't normally encounter longer delays unless there's an actual problem of some sort.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-08-11T15:49:35.543" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18788" PostTypeId="1" CreationDate="2015-08-11T16:15:32.227" Score="0" ViewCount="376" Body="&lt;p&gt;If you have a plane like a Cub or Scout, is it legal to land on a beach, river bank, or other similar feature or will the FAA take your certificate if you do it? I can't find any info on this anywhere but see lots of YouTube videos of people doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is not in reference to an airplane with an emergency, I'm talking about a voluntary, intentional landing on a beach with the purpose of fishing or camping, like is done with many bush planes.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2015-08-11T16:50:37.090" LastActivityDate="2015-08-13T05:44:44.650" Title="Legal to land on a beach?" Tags="&lt;faa-regulations&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2015-08-11T17:08:50.490" ContentLicense="CC BY-SA 3.0" />
  <row Id="18789" PostTypeId="1" AcceptedAnswerId="18790" CreationDate="2015-08-11T16:38:50.977" Score="10" ViewCount="4805" Body="&lt;p&gt;This question doesn't relate to the actual speed of the aircraft, but of the blades themselves. I have heard helicopters had problems of this happening if the rotors spin too fast it can break the sound barrier, so could this happen to a turboprop?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-10-05T16:33:52.757" LastActivityDate="2018-04-17T23:40:56.773" Title="Can turboprop blades break the sound barrier?" Tags="&lt;commercial-aviation&gt;&lt;supersonic&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18790" PostTypeId="2" ParentId="18789" CreationDate="2015-08-11T16:48:26.007" Score="12" Body="&lt;p&gt;Can it happen: Yes &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it happen: Generally no &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a matter of the pure physics propeller tips can go supersonic and some times do. There is at least one case of this being done &lt;a href=&quot;http://www.enginehistory.org/Allison/XF-84Propulsion.html&quot; rel=&quot;noreferrer&quot;&gt;by design&lt;/a&gt; on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Republic_XF-84H&quot; rel=&quot;noreferrer&quot;&gt;XF-84H&lt;/a&gt; which was built to be one of the fastest propeller planes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gpUwW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gpUwW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main issue it faced was the noise generated by its supersonic prop. It is considered one of the loudest aircraft ever made as its prop was supersonic even at idle speeds. Due to the shock waves generated by breaking the sound barrier great care is often taken to ensure that propellers don't go supersonic.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2015-10-05T19:57:38.893" LastActivityDate="2015-10-05T19:57:38.893" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18791" PostTypeId="2" ParentId="18782" CreationDate="2015-08-11T16:48:38.890" Score="7" Body="&lt;p&gt;Calling the &quot;airport in sight&quot; is an optional call by the pilots and only affects your approach clearance, not your landing clearance.  Prior to any instrument landing you will receive an approach clearance.  A clearance for an ILS approach is the same whether you are flying to category I, II or III minimums.  If you report &quot;airport in sight&quot; to the approach controller they may issue you a &quot;visual approach&quot; instead.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you are established on final approach you will be handed off to the tower and they will issue the landing clearance.  In IMC you will receive a landing clearance well before you can see the runway and there is no reason to call the controller when you see the airport.  They will know you can see the runway when you land on it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the handoff to tower occurs around the final approach fix or when established on the approach, &lt;em&gt;not&lt;/em&gt; when you have visual contact with the airport.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-08-11T16:48:38.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18793" PostTypeId="1" CreationDate="2015-08-11T18:02:09.843" Score="1" ViewCount="123" Body="&lt;p&gt;I know that hydrogen has a reaction with oxygen like with jet fuel, but could the engine run on hydrogen.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="64" LastEditDate="2015-08-11T18:09:57.897" LastActivityDate="2015-08-11T18:09:57.897" Title="If you replaced jetfuel with hydrogen could the aircraft engine work on hydrogen?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-08-11T18:10:06.503" ContentLicense="CC BY-SA 3.0" />
  <row Id="18796" PostTypeId="1" AcceptedAnswerId="18799" CreationDate="2015-08-11T18:37:00.417" Score="18" ViewCount="7312" Body="&lt;p&gt;For ground reference maneuvers, I know there are many ways that I can know wind direction: smoke, circling, weather reports from nearby airport and so on. However, how can I determine the wind direction by looking at water? I've tried to look for detailed explanations about it but I have found nothing useful. Can somebody help me to understand this issue? I would appreciate if there is any graphic materials.&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="3825" LastEditDate="2015-08-13T04:41:27.183" LastActivityDate="2015-08-26T13:01:35.360" Title="How can I know where wind is coming from by looking at water?" Tags="&lt;wind&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18797" PostTypeId="2" ParentId="18783" CreationDate="2015-08-11T18:57:18.030" Score="4" Body="&lt;p&gt;Given that you want to stay in the pattern you could use the upwind leg to avoid flying over the runway.  This is, from base go to upwind, then crosswind, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others posted there is no standard holding pattern.  For VFR traffic there are no holds either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pattern may become congested quickly.  Your best bet is to divert until the situation improves.&lt;/p&gt;&#xA;" OwnerUserId="651" LastActivityDate="2015-08-11T18:57:18.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18798" PostTypeId="2" ParentId="18796" CreationDate="2015-08-11T19:21:31.890" Score="5" Body="&lt;p&gt;Waves move in the direction of the wind, and form long lines.&#xA;Cresting waves always break downwind &amp;amp; whitecaps are generally pretty easy to spot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So look for parallel lines of waves.  A line perpendicular to the wave-line will be directly-into / directly-away from the wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the waves are very large or moving very slowly, it may be hard to determine which direction they're moving, but at least you'll have an axis for the wind direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the water is calm enough that you cannot figure out wind direction, it generally means there isn't much wind to speak of.  It generally only takes a couple knots of wind speed to make discernible waves.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-08-11T19:21:31.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18799" PostTypeId="2" ParentId="18796" CreationDate="2015-08-11T19:29:26.300" Score="21" Body="&lt;p&gt;The easiest way to tell the direction of the wind when you're near the water is to look for something on the shore that indicated wind direction (beaches often have flags on them)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Barring that there are a bunch of other clues that should be familiar to any sailor (or seaplane pilot) which you can borrow:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Boats lying at anchor weathervane and automatically point into the wind&lt;/strong&gt;&lt;br&gt;&#xA;This isn't 100% reliable: Some boats will set two anchors (fore and stern) and won't weathervane. Also when the tide is shifting boats will swing to align with the tide if it's stronger than the wind. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Boats lying at anchor sometimes have a flag on them&lt;/strong&gt;&lt;br&gt;&#xA;Flags on a boat at anchor work the same way as flags on land - they're excellent indicators of wind direction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;On calm bodies of water the wind creates visible surface ripples&lt;/strong&gt;&lt;br&gt;&#xA;The concave side of these ripples is the windward side.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/LeGSu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LeGSu.jpg&quot; alt=&quot;Wind Direction from Ripples&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Visualize the water as being a large bowl of soup - now blow on the soup. The ripples will have the same shape.)&lt;br&gt;&#xA;This same principle applies to larger waves as well (other factors could cause the dominant breeze along a shoreline to not be quite perpendicular to the waves, but if your concern is ground reference maneuvers it's &quot;close enough&quot;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;&quot;Wind Streaks&quot; on the sea indicate wind direction&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://collierseagrant.blogspot.com/2011/01/foamy-streaks-on-waterlangmuir.html&quot; rel=&quot;noreferrer&quot;&gt;Wind streaks&lt;/a&gt; are somewhat ambiguous in that they're aligned with the wind, but don't tell you which way it's blowing: You have to figure that out for yourself (for example by looking at the shape of the waves as described above).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3gfuc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3gfuc.png&quot; alt=&quot;Wind Streaks&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Surf spray gives wind speed and direction&lt;/strong&gt;&lt;br&gt;&#xA;Waves breaking will produce spray that blows downwind - I couldn't find a good illustration for this, but the finer spray tends to blow, while heavier drops just fall. The distance the spray blows gives an approximate indication of wind speed.&lt;br&gt;&#xA;It would take some pretty heavy seas to produce visible spray at altitude though, and you're more likely to see foam and whitecaps in that case&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Foam or Whitecaps provide wind speed and direction&lt;/strong&gt;&lt;br&gt;&#xA;Foam or whitecaps provide an indication of direction (the foam appears to move &lt;em&gt;upwind&lt;/em&gt; - into the wind) and speed (it generally takes winds of 10-15 knots or more to produce whitecaps and foam).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-11T19:29:26.300" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18800" PostTypeId="1" AcceptedAnswerId="18803" CreationDate="2015-08-11T19:34:00.323" Score="4" ViewCount="2464" Body="&lt;p&gt;Every NetJets aircraft that I've seen has a tail number ending in QS. Knowing aircraft operators, I'm sure it stands for something, but I don't know what.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What does the QS stand for in NetJets tail numbers?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-08-14T00:19:16.783" Title="What does the NetJets &quot;QS&quot; stand for?" Tags="&lt;terminology&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18801" PostTypeId="2" ParentId="18778" CreationDate="2015-08-11T19:38:49.860" Score="4" Body="&lt;p&gt;With the exception of abbreviations (like FSDO, pronounced &lt;code&gt;fizz dough&lt;/code&gt;) there's not much &quot;jargon&quot; in aviation that's not a standard word in whatever language you're speaking. Words like &quot;dihedral&quot;, &quot;anhedral&quot;, &quot;aileron&quot;, etc. should certainly show up in a dictionary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The abbreviations are &quot;tribal knowledge&quot; the same way they are in any other field (e.g. SCSI, SATA, IMAP in the tech field). I'm not aware of any authoritative compendium of pronunciations.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-11T19:38:49.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18802" PostTypeId="2" ParentId="18778" CreationDate="2015-08-11T19:55:52.473" Score="3" Body="&lt;p&gt;There probably isn't a reference, per se, but you can hear a lot of these words in context a few of ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.liveatc.net&quot; rel=&quot;nofollow&quot;&gt;http://www.liveatc.net&lt;/a&gt; - Is one great example.  It will allow you to listen to live ATC, and they'll be saying a lot of the same world you want to hear.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.pilotedge.net&quot; rel=&quot;nofollow&quot;&gt;https://www.pilotedge.net&lt;/a&gt; - Along the same lines, but instead it's a plugin for your flight simulator that allows you to interact with actual ATC professionals on a virtual ATC network.  Not only good for listening, but also for learning to use a lot of the words.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.youtube.com&quot; rel=&quot;nofollow&quot;&gt;http://www.youtube.com&lt;/a&gt; - Okay, this probably didn't need to be listed like this, but it's also useful :).  There are A LOT of videos online for learning aviation, and they probably use many of the words you are curious about.  So I'd try that as well.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Between all these resources it should be pretty easy to get at the &quot;tribal knowledge&quot; voretaq7 referenced in his answer.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-08-11T19:55:52.473" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18803" PostTypeId="2" ParentId="18800" CreationDate="2015-08-11T20:06:02.413" Score="4" Body="&lt;p&gt;The &quot;QS&quot; first stood for quarter share, according to the &lt;a href=&quot;https://books.google.com/books?id=tURRT6QU1jIC&amp;amp;lpg=PA96&amp;amp;ots=qoMON7rF5o&amp;amp;dq=netjets%20quarter-share&amp;amp;pg=PA97#v=onepage&amp;amp;q=netjets%20quarter-share&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;1998 issue of Flying&lt;/a&gt;. Each aircraft will have multiple owners to help bring the cost down for the owner.&lt;/p&gt;&#xA;" OwnerUserId="9766" LastEditorUserId="167" LastEditDate="2015-08-14T00:19:16.783" LastActivityDate="2015-08-14T00:19:16.783" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18804" PostTypeId="2" ParentId="18800" CreationDate="2015-08-11T20:06:32.667" Score="3" Body="&lt;p&gt;In the United States, tail numbers can be arbitrarily assigned, assuming it is available and formatted per &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/forming_nnumber/&quot; rel=&quot;nofollow&quot;&gt;FAA requirements&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NetJets uses QS to identify their planes. According to an &lt;a href=&quot;https://books.google.com/books?id=gu1u7T9Lr7AC&amp;amp;lpg=PA80&amp;amp;ots=5wYb2M3PO9&amp;amp;dq=netjets%20%22quality%20service%22&amp;amp;pg=PA81#v=onepage&amp;amp;q=netjets%20%22quality%20service%22&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;article in the May 2002 issue of &lt;em&gt;Flying&lt;/em&gt; magazine&lt;/a&gt;, &quot;QS represents Quality Service,&quot; (page 82).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-08-11T20:20:27.500" LastActivityDate="2015-08-11T20:20:27.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18806" PostTypeId="1" AcceptedAnswerId="18807" CreationDate="2015-08-11T20:34:46.280" Score="6" ViewCount="1033" Body="&lt;p&gt;Since hydrogen is lighter than air, would hydrogen fuel tanks help provide lift for the airplane?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="824" LastEditDate="2020-09-22T05:12:49.640" LastActivityDate="2020-09-23T09:48:18.620" Title="Would hydrogen fuel tanks on an airplane increase lift?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;&lt;hydrogen&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18807" PostTypeId="2" ParentId="18806" CreationDate="2015-08-11T20:57:53.003" Score="14" Body="&lt;p&gt;Let's do some quick math. Air has a density of about 1.3 g/L and hydrogen has a density of about 0.09 g/L. The best case for lifting force would be storing the hydrogen at the same pressure as the surrounding air. This means that every L of hydrogen can displace 1.21 g of air, reducing the density of the aircraft. The amount of air displaced by the aircraft (and therefore the &lt;a href=&quot;https://en.wikipedia.org/wiki/Buoyancy&quot; rel=&quot;noreferrer&quot;&gt;buoyancy&lt;/a&gt;) would not change, but the density of the aircraft in that space would decrease. This would decrease the lift needed, but let's see by how much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The greatest amount of free volume in an aircraft (that isn't part of the pressurized section of the fuselage) is the fuel tanks. An A380 has a fuel capacity of about 323,000 L. If we consider filling half of that with hydrogen, this would result in a total reduction of about 190 kg. An A380 has a max takeoff weight of 575,000 kg. This change would help but would be very small compared to the total lift needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As David Richerby points out, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft&quot; rel=&quot;noreferrer&quot;&gt;hydrogen needed as fuel&lt;/a&gt; would need to be pressurized (if not liquified) to fit enough onboard. This would increase the density above that of any displaced air, which would instead add weight to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the hydrogen could be produced instead of stored. Newer aircraft do have something called an &lt;a href=&quot;https://en.wikipedia.org/wiki/Inerting_system&quot; rel=&quot;noreferrer&quot;&gt;OBIGGS&lt;/a&gt;, or onboard inert gas generating system. This system generates nitrogen which is used to fill the space in fuel tanks after the fuel is used. Being an inert gas, nitrogen can lower the amount of oxygen in the space below what would be required for ignition of the fuel vapors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this system splits nitrogen out of air, considering that our atmosphere is mostly nitrogen. Hydrogen would have to come from somewhere else, usually water, which would add more weight. Another problem with hydrogen is that when added to air &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen_safety&quot; rel=&quot;noreferrer&quot;&gt;it can be explosive all by itself&lt;/a&gt;, which would make the situation even worse. Considering the minor benefit, this would not be a system worth installing on an airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the feasibility of a hydrogen powered aircraft, &lt;a href=&quot;http://crgis.ndc.nasa.gov/crgis/images/8/8f/PEN00311.pdf&quot; rel=&quot;noreferrer&quot;&gt;NASA did a study&lt;/a&gt; and decided that this is not a good source of power for an aircraft. &lt;a href=&quot;https://aviation.stackexchange.com/q/18809/1696&quot;&gt;The volume and weight required&lt;/a&gt; to store even liquid hydrogen would be too much for the aircraft to be very useful.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-12T15:39:27.260" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18808" PostTypeId="2" ParentId="18806" CreationDate="2015-08-11T21:53:26.337" Score="6" Body="&lt;p&gt;No. If you want to use hydrogen as fuel, you need a lot of it, which means you need to pressurize it. Hydrogen is less dense than air when it's at ordinary atmospheric pressure but, as you start to pressurize it (i.e., fit a greater mass of hydrogen into a fixed volume), that advantage decreases. Worse, if your fuel is pressurized, you need to store it in a strong tank and strong means heavy.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-08-11T21:53:26.337" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18809" PostTypeId="1" AcceptedAnswerId="18816" CreationDate="2015-08-11T22:20:07.413" Score="4" ViewCount="1130" Body="&lt;p&gt;So called &quot;renewable energy&quot; is a buzzword these days. &lt;a href=&quot;https://www.youtube.com/watch?v=TFakFh_1XSw&quot; rel=&quot;nofollow noreferrer&quot;&gt;Auto manufacturers&lt;/a&gt; are starting to roll out hydrogen powered cars. Hydrogen may not &lt;em&gt;currently&lt;/em&gt; be the &lt;a href=&quot;https://aviation.stackexchange.com/q/13042/6886&quot;&gt;most efficient&lt;/a&gt; or economic fuel for jet engines, but that doesn't mean there are companies working on this issue or even a new kind of engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any such programs in existence today?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="824" LastEditDate="2020-09-21T20:02:51.957" LastActivityDate="2020-09-21T22:08:15.713" Title="Are there any programs to build a hydrogen powered airplane?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;fuel&gt;&lt;aircraft-manufacturer&gt;&lt;hydrogen&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18810" PostTypeId="2" ParentId="18782" CreationDate="2015-08-12T00:03:06.367" Score="0" Body="&lt;p&gt;Around here we'll typically get our handoff right at the FAF (they seem to know exactly when you're busiest and hit you with more workload right then :-)  ).  The landing clearance comes afterwards.  Sometimes immediately after communications is established, sometimes not until down near DH (depending on other traffic, etc).&lt;/p&gt;&#xA;" OwnerUserId="49" LastActivityDate="2015-08-12T00:03:06.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18811" PostTypeId="1" AcceptedAnswerId="18813" CreationDate="2015-08-12T03:49:39.203" Score="12" ViewCount="8290" Body="&lt;p&gt;Surely it would get more thrust from a three blade variable pitch propeller. From what I've read it's all about the area swept and also should be far enough apart to not cause too much interference. Besides having a constant speed prop would allow for a wider range of optimum operation.&lt;/p&gt;&#xA;" OwnerUserId="9769" LastEditorUserId="2143" LastEditDate="2015-11-01T23:38:10.740" LastActivityDate="2016-04-10T05:57:27.857" Title="Why does the Cessna 172S Skyhawk use only two blade fixed pitched prop?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;cessna-172&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18813" PostTypeId="2" ParentId="18811" CreationDate="2015-08-12T04:07:36.110" Score="25" Body="&lt;p&gt;You're not wrong, but a fixed pitch two-blade prop has a pretty big advantage: &lt;strong&gt;&lt;em&gt;it's cheap&lt;/em&gt;&lt;/strong&gt;. Cheap to buy, cheap to install, cheap to maintain, cheap to repair. 172s are predominantly trainers in FBO fleets, and cheap is the winner. The efficiencies of a better prop are lost when you're just doing pattern work and short cross countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;http://hartzellprop.com/faq/technical-questions/&quot;&gt;when you're not climbing, a two-bladed prop is actually going to be more efficient, not less&lt;/a&gt; as it's creating less drag. According to the linked Hartzell FAQ:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Depending on the combination of [engine power, operating RPM for the propeller, diameter limitations, design requirements, etc] a 2-blade propeller may be most efficient, but as power increases additional blades are generally required to efficiently utilize the increased power.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means that on a 160 horsepower engine like the 172 is rocking, you aren't going to see particularly tangible benefits from increasing the number of blades. Going to a constant speed prop would, on the other hand, give you greater utilization of power across the entire flight envelope.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;For example...&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An overhauled McCauley fixed pitch 2-blade propeller that fits a Cessna 172 is &lt;strong&gt;$2,100&lt;/strong&gt; on ebay. It has no moving parts (I mean, aside from &lt;em&gt;itself&lt;/em&gt;) and is relatively easy to balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A (non-overhauled?) Hartzell 3-blade constant speed prop off a Piper PA-46-350 Malibu Mirage is &lt;strong&gt;$15,000&lt;/strong&gt; on ebay with &lt;em&gt;no logs&lt;/em&gt;, which is usually a bad sign. It's not a direct comparison to, say, the prop on a C182, but it's probably in the ballpark. It's harder to balance, and requires more maintenance to make sure the constant speed mechanism is up to snuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was only able to find prices on ebay, which isn't the most scientific comparison ever, but it's a start.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-08-12T04:42:48.733" LastActivityDate="2015-08-12T04:42:48.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18814" PostTypeId="2" ParentId="7687" CreationDate="2015-08-12T04:21:35.917" Score="8" Body="&lt;p&gt;You can land wherever you want as far as the aviation regulations are concerned. The airspace is irrelevant. You may, however, be breaking a range of different state laws. Generally speaking, the things to watch out for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) Landing on private property without express permission is trespassing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Landing anywhere a person would be likely to be may be reckless endangerment&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) Landing in such a way that would cause an unnecessary emergency response can result in a charge for intentional or careless use of emergency services (you can avoid this by calling them ahead of time and telling them you do not need emergency services)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, you can land on any public land that is not a place someone else would be (like a road). If you land on a road without good reason, it could be construed as reckless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In remote areas like Alaska landing off field is routine and occurs as a matter of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots that fly in back woods areas and land off field all the time are called &quot;bush pilots&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-03-31T17:00:00.443" LastActivityDate="2016-03-31T17:00:00.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18815" PostTypeId="2" ParentId="18783" CreationDate="2015-08-12T04:26:28.217" Score="-3" Body="&lt;p&gt;A holding pattern just means circling the airport. If you had to wait there, that is what you would do, circle the airport. If there are so many aircraft, that the pattern altitude is full, then you start stacking 2000 feet, 3000 feet, 4000 feet, etc.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-12T04:26:28.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18816" PostTypeId="2" ParentId="18809" CreationDate="2015-08-12T05:21:29.293" Score="17" Body="&lt;p&gt;Aviation is very energy-hungry. While hydrogen is quite efficient in terms of energy per mass (&lt;a href=&quot;http://www.wolframalpha.com/input/?i=energy%20content%20of%20hydrogen&quot; rel=&quot;nofollow noreferrer&quot;&gt;141.8 MJ/kg&lt;/a&gt;), it is awful in terms of energy per volume. Aircraft today use their wings for fuel storage, which helps to reduce bending loads and uses a volume unsuitable to transport payload. This will not work for hydrogen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest problem is &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen_storage&quot; rel=&quot;nofollow noreferrer&quot;&gt;storage&lt;/a&gt;, and none of the solutions is really attractive:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cryogenic: Storing the hydrogen at a temperature where it is liquid (below 20°K) greatly reduces volume demands, but now you need to add insulation, and even then the energy per volume is only a quarter compared to hydrocarbons. This is used in rockets, because they can rely on extensive ground support before launch and use up the stuff in a few minutes. Airliners, however, need to store their fuel over tens of hours, so their hydrogen tanks will be much heavier and bulkier than those of rockets.&lt;/li&gt;&#xA;&lt;li&gt;Compressed: This avoids the energy input for liquefaction, but now you need a strong and heavy pressure vessel. Current &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen_tank&quot; rel=&quot;nofollow noreferrer&quot;&gt;gaseous hydrogen storage&lt;/a&gt; uses up to 700 bar pressure, but even then the volume demand is six times higher than that of kerosene for the same energy content.&lt;/li&gt;&#xA;&lt;li&gt;Hydrides: Some metals like magnesium or &lt;a href=&quot;https://en.wikipedia.org/wiki/Sodium_aluminium_hydride&quot; rel=&quot;nofollow noreferrer&quot;&gt;sodium&lt;/a&gt; can bind hydrogen and release it when heated. However, even in the most efficient compounds like sodium tetrahydroaluminate, only 7.4% of mass is useable hydrogen, making this exquisitely unsuitable for mass-critical applications like aviation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Currently a &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen_storage#Cryo-compressed&quot; rel=&quot;nofollow noreferrer&quot;&gt;mixture of cryogenic and compressed storage&lt;/a&gt; looks the most attractive and has been tested widely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first (partially) hydrogen powered aircraft was the LZ-127 Zeppelin which used a mixture of gasses of equal mass per volume as air (&lt;a href=&quot;https://en.wikipedia.org/wiki/Blau_gas&quot; rel=&quot;nofollow noreferrer&quot;&gt;Blaugas&lt;/a&gt;) to power its engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev designed and flew the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-155&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-155&lt;/a&gt;, the first hydrogen-powered heavier-than-air aircraft, in 1988. The results showed that the principle worked, but could not compete with kerosene.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydrogen-powered_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;several demonstrators are in operation&lt;/a&gt;, but none with the hope of widespread application - as it stands, binding hydrogen chemically to carbon will still give the best way of storage (liquid and unpressurized) for aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydrogen becomes the best source of energy only when combustion speed is critical, such as in supersonic combustion ramjets (&lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222#9222&quot;&gt;scramjets&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-01-24T01:25:05.017" LastActivityDate="2020-01-24T01:25:05.017" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="18817" PostTypeId="2" ParentId="18806" CreationDate="2015-08-12T05:42:50.753" Score="2" Body="&lt;p&gt;It would increase lift if it were unpressurized. Of course, it would also increase volume by a few orders of magnitude if it were going to produce enough lift to matter in the context of a significantly-sized aircraft, which would lead to form drag penalties that far outweighed the lift benefit for craft that fly anything close to the speeds used in modern airliners. This can, of course, work for much slower aircraft like &lt;a href=&quot;https://en.wikipedia.org/wiki/Airship&quot; rel=&quot;nofollow noreferrer&quot;&gt;airships&lt;/a&gt;, though such use can have &lt;a href=&quot;https://en.wikipedia.org/wiki/Hindenburg_disaster&quot; rel=&quot;nofollow noreferrer&quot;&gt;undesirable consequences&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's pressurized, it will be more dense than air and, therefore, will not create lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aforementioned undesirable consequences look something like this:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/kZhWu.jpg&quot; alt=&quot;Undesirable consequences of using Hydrogen for lift generation.&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-12T06:58:30.517" LastActivityDate="2015-08-12T06:58:30.517" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="18820" PostTypeId="1" AcceptedAnswerId="18821" CreationDate="2015-08-12T08:08:48.020" Score="11" ViewCount="3720" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;During the Concorde's takeoff run, this piece of debris still lying on the runway, was run over, cutting a tyre and rupturing it.  A &lt;strong&gt;runway inspection&lt;/strong&gt;, scheduled for 15h, had not been carried out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How is a runway inspection carried out? How often is a runway inspection done? And, what all is checked in a runway inspection? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-08-12T10:19:02.997" Title="How is a runway inspection carried out?" Tags="&lt;safety&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18821" PostTypeId="2" ParentId="18820" CreationDate="2015-08-12T09:51:48.937" Score="8" Body="&lt;p&gt;The answer will differ a bit from airfield to airfield but here is a &lt;a href=&quot;http://www.eastmidlandsairport.com/magweb.nsf/AttachmentsByTitle/AOI02/$file/AOI%202%20-%20Movement%20Area%20Inspection%20and%20Reporting.pdf&quot;&gt;typical inspection procedure for East Midlands in the UK&lt;/a&gt;(EGNX).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inspection is carried out first thing in the morning and last thing at night, then at 2 hour intervals throughout the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is carried out by a vehicle in co-ordination with ATC who might shut the runway down for a few minutes.  The vehicle must get permission from ATC to enter the runway and must report on leaving. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approach will co-ordinate the arrivals, by extending them slightly, so that no-one has to hold or go around (hopefully).  It is also possible to do half the runway as a departing aircraft lines up, leave the runway at a turn off, wait for the departing aircraft, then complete the inspection before the next departure.  There are several ways to do it without causing disruption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vehicle enters the runway and drives the complete length visually checking the items on the inspection list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The document gives you a complete list of items to check but essentially it is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Clear of FOD.&lt;/li&gt;&#xA;&lt;li&gt;Markings and signs in good condition and visible. &lt;/li&gt;&#xA;&lt;li&gt;Lighting working and undamaged.&lt;/li&gt;&#xA;&lt;li&gt;Runway surface not damaged.&lt;/li&gt;&#xA;&lt;li&gt;Oil and fuel spills.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-08-12T10:19:02.997" LastActivityDate="2015-08-12T10:19:02.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18822" PostTypeId="2" ParentId="18806" CreationDate="2015-08-12T10:15:35.097" Score="8" Body="&lt;p&gt;Buoyancy (a.k.a. static lift) depends on the volume of the object. If you put something else in the tanks, the buoyancy &lt;strong&gt;does not change&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;What &lt;em&gt;can&lt;/em&gt; change, however, is the weight. If you wanted to use it as fuel, you'd have to take such amount as to get the same combustion heat as you get from kerosene. Hydrogen has lower¹ heating value 119.96 MJ/kg and kerosene has ~43 MJ/kg (²), so you would need almost three (2.79) times less hydrogen by weight. This is totally unrelated to its density, but it is the only way how it can offer advantage as fuel.&lt;/p&gt;&#xA;&lt;p&gt;However:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You'd still need to squeeze a lot of it into the aircraft, which means either &lt;em&gt;huge&lt;/em&gt; pressure or &lt;em&gt;very cold&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Even liquid hydrogen has density of only 70.85 kg/m³ (gaseous at 300 bar has only 26.96 kg/m³) compared to 800 kg/m³ for kerosene, so even for three times less weight you'd still need four times larger fuel tanks and they would come with higher form drag and higher weight. They would also have slightly higher buoyancy, but the drag penalty would be higher than any gain from that.&lt;/li&gt;&#xA;&lt;li&gt;Dealing with stuff colder than −253 °C is &lt;em&gt;complicated&lt;/em&gt; and it takes a lot of energy to keep it cool it and keep it cold. For spacecrafts the weight advantage is so important that its worth it, but for aircraft it isn't.&lt;/li&gt;&#xA;&lt;li&gt;Compressed hydrogen is not really an option. The tanks would be heavier than what you could save in the weight of fuel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;So overall hydrogen does not have any advantage to offer for aircraft. It only has it for spacecraft that leave the atmosphere quickly so they don't care about aerodynamic drag much, but care about weight a lot.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;¹ Note that “lower heating value” is a technical term. Fuels have two heating values, lower, which is for leaving the products in gaseous state, and higher, which includes the enthalpy of condensation if the products would be liquid at room temperature and standard pressure, as is the case with common combustion product, water.&lt;/p&gt;&#xA;&lt;p&gt;² Unlike hydrogen, kerosene is a mixture with some tolerance for composition, so it does not have a more accurate heating value, because it is allowed to vary from batch to batch.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2020-09-23T09:48:18.620" LastActivityDate="2020-09-23T09:48:18.620" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="18823" PostTypeId="2" ParentId="18780" CreationDate="2015-08-12T10:56:12.253" Score="8" Body="&lt;p&gt;While Simon has told you about why ALL Fire Engines SHOULD better be yellow/green, not red, he did not tell you why all Airport Fire Trucks you have seen are yellow, and all normal Fire Trucks you have seen are red.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PBS's &quot;Firehouse Primer&quot; on the history of red fire engines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Before firefighting was a paid profession, most communities were served by volunteer fire departments. These firemen didn't have much money to spend on upkeep, and at the time red was the least expensive color of paint. Red wasn't the only color used, however. Before it merged with the force in Manhattan, the Brooklyn Fire Department painted its apparatus a two-tone green to distinguish them from the red apparatus of the Metropolitan Fire Department. Today, there are still different colored fire engines, but red is the most common color out of tradition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't know whether this is true or just an anecdote, but it's a nice story nevertheless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While in the US, where fire fighting is a local issue, you will see yellow fire engines with some fire dept's (mostly in rural areas, I guess it's because you have long unlighted stretches of street there), in your native Brazil, the central government has decided to use red for all engines. This is the same in my native Germany, where the color mandated by law for fire trucks used on public streets has changed slightly over the years, from a dark red over a orangeish red to a retroreflecting orange-red. The Swiss, where fire fighting is a local issue as well, have mostly switched to yellow fire engines for visibility reasons. So I guess that you have only been to red-engine territory until now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airports, it's a different issue: Unless ordered otherwise, Oshkosh's (the US market leader) airport fire engine lineup is painted green/yellow. Rosenbauer (big player in Europe) on the other hand has a red lineup. While you can order other colors, most customers stick to  the default. So my best guess is that you haven't attended any plane evacuations in Europe until now.&lt;/p&gt;&#xA;" OwnerUserId="1745" LastEditorUserId="1745" LastEditDate="2015-08-12T12:07:15.767" LastActivityDate="2015-08-12T12:07:15.767" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18824" PostTypeId="1" AcceptedAnswerId="18825" CreationDate="2015-08-12T12:35:17.720" Score="9" ViewCount="2319" Body="&lt;p&gt;There are quite a number of publications about airplane boarding which all usually begin with something like:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Boarding is an expensive process that costs so much, that by reducing the boarding time airlines could save a lot of money.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, none of the publications I've read says explicitly why the costs are reduced. Of course there is at least one obvious reason:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A shorter ground time reduces delays and thus the number of missed connecting flights, leading to fewer liabilities.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Further there is the possibility that a plane can do an additional flight during the day. But if a plane does 5 flights a day and saves 5 minutes per boarding, then the resulting 25 minutes would not suffice (at least in countries with start restrictions over the night).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So therefore the question: What factors play a role in saving money by reducing boarding time?&lt;/p&gt;&#xA;" OwnerUserId="7988" LastEditorUserId="3677" LastEditDate="2015-08-12T13:00:33.107" LastActivityDate="2015-08-12T22:08:53.033" Title="Why will reducing the boarding time reduce the costs?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;&lt;boarding&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18825" PostTypeId="2" ParentId="18824" CreationDate="2015-08-12T12:43:47.710" Score="15" Body="&lt;p&gt;&lt;strong&gt;It's not as much boarding as much as standing around does not generate any revenue.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Use Your Capital Assets:&lt;/strong&gt; 25 minutes a day is a lot, and in some cases is equivalent to a domestic leg. Rather than arriving at 23:00, you could arrive at 22:30 and still squeeze in an additional short flight before midnight. If you're flying 10 flights a day and you can now fly 11, you're doing 10% more work with the same amount of assets. Estimates for a flight hour of a B737 are ≅ \$3000-\$3500 in the US, for an aircraft worth perhaps $60 million. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Fixed Costs:&lt;/strong&gt; You're looking at a bit of fixed costs, such as insurance. The more flying time you can squeeze out of the plane, the cheaper each hour will become on average.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Less Staff, More Product:&lt;/strong&gt; You need a certain number of ground staff. If you can cut the time required for an aircraft to be handled by ground staff by 20% (50 → 40 minutes), that potentially means that they could handle an additional aircraft in their shift. This principle applies for airline flight crew, as well. It's a lot cheaper to let the your pilot fly a few hours more than needing to hire another one.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Standing around is not always cheap either:&lt;/strong&gt; Depending on airport cost/fee structure, you may be charged less for the ground time. This is not only standing around; for instance, Munich airport charges you €44 for every 30 minutes of using a ground power unit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-12T18:29:38.100" LastActivityDate="2015-08-12T18:29:38.100" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18826" PostTypeId="2" ParentId="18789" CreationDate="2015-08-12T14:13:22.877" Score="7" Body="&lt;p&gt;It seems sometimes happens on the Tupolev Tu-95 &quot;Bear&quot; long-range strategic bomber.&#xA;According to various sources like &lt;a href=&quot;http://civilianplanespotters.blogspot.it/2010/01/tupolev-tu-95-bear-worlds-noisiest.html&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; (the first result from a &lt;a href=&quot;https://www.google.it/search?q=Tu-95+sonic+blade&amp;amp;sourceid=ie7&amp;amp;rls=com.microsoft:it-IT:IE-Address&amp;amp;ie=&amp;amp;oe=&amp;amp;gfe_rd=cr&amp;amp;ei=m0_LVZCyC6aO8QfRsZPgAw&amp;amp;gws_rd=ssl#q=Tu-95+sonic+propeller&quot; rel=&quot;noreferrer&quot;&gt;Google search&lt;/a&gt;), the tip of the propeller goes transonic while turning at full rpm with a decrease in performances and a severe increase in &lt;em&gt;noise&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tu-95 has straight blades, like many old turboprop aircrafts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Jf95S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Jf95S.jpg&quot; alt=&quot;Bear&amp;#39;s propellers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To partially overcome this problem, modern turboprops use &quot;scimitar&quot; blades, like the one on the C-130J:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g8xyz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g8xyz.jpg&quot; alt=&quot;C-130J propellers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the same way a swept wing is more efficient at high speed in comparison to a straight wing, at high tip speed, a scimitar blade is more efficient than a straight blade.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-08-12T14:13:22.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18827" PostTypeId="2" ParentId="18780" CreationDate="2015-08-12T14:28:33.640" Score="8" Body="&lt;p&gt;It's because it is the color specified by the Federal Aviation Administration and the only color of firefighting vehicle they will participate in funding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5210_5d.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory Circular AC 150/5210-5D&lt;/a&gt; states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Aircraft Rescue and Fire Fighting (ARFF) Vehicles.&lt;/strong&gt; Yellowish-green is the vehicle color standard.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;APPLICATION.&lt;/strong&gt;  The Federal Aviation Administration (FAA) recommends the guidelines and standards in this Advisory Circular for vehicles operating in the airport AOA. In general, use of this AC is not mandatory. &#xA;  &lt;strong&gt;&lt;em&gt;However&lt;/em&gt;&lt;/strong&gt;, use of this AC is mandatory for vehicles funded with federal grant monies through the Airport Improvement Program (AIP) and/or with revenue from the Passenger Facility Charges (PFC) Program. See Grant Assurance No.&amp;nbsp;34, “Policies, Standards, and Specifications,” and PFC Assurance No.&amp;nbsp;9, “Standard and Specifications.”  [emphasis in original]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9776" LastEditorUserId="946" LastEditDate="2015-08-12T22:07:22.957" LastActivityDate="2015-08-12T22:07:22.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18828" PostTypeId="1" AcceptedAnswerId="33443" CreationDate="2015-08-12T15:39:39.590" Score="8" ViewCount="506" Body="&lt;p&gt;When a runway inspection determines that there are bulbs out on any of the runway or taxiway lighting fixtures, what is involved in changing them?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the runway/taxiway need to be shut down for &lt;em&gt;all&lt;/em&gt; bulb changes? (Obviously for center line markers, but what about edge markers?)&lt;/li&gt;&#xA;&lt;li&gt;What is involved in changing bulbs for any sort of landing system lighting? (i.e. ALS, PAPI, VASI, etc)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="3825" LastEditDate="2015-08-12T23:41:29.580" LastActivityDate="2016-11-27T11:43:11.653" Title="What is involved in changing runway/taxiway/approach lighting?" Tags="&lt;airport-lighting&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18829" PostTypeId="2" ParentId="18828" CreationDate="2015-08-12T17:25:56.403" Score="1" Body="&lt;p&gt;Runways are not closed for bulb changes. Closing a runway is a big hairy deal that is not something you do unless you have to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally what happens if it is a multi-runway airport is that they wait until the runway is not being used because of cross wind conditions, then a guy in a yellow truck with flashing lights drives out and makes the replacement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is only one runway, or if something has to be done to an active runway (like remove a turtle or something), then the FBO operator or tower just warns off any approaching aircraft on the CTAF while the dude in the yellow truck scoots out there and does it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally they try to stay off the runway with the actual truck and minimize the time they are out there. So, for example, with a turtle what happens is the guy drives the truck on the grass until he is parallel with the turtle, then he leaves the truck's lights on, runs out, grabs the turtle, and runs off the runway again. He then drives the truck back (on the grass) and the FBO resumes operations.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-12T17:25:56.403" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="18830" PostTypeId="2" ParentId="18824" CreationDate="2015-08-12T22:08:53.033" Score="2" Body="&lt;p&gt;Finishing boarding of a particular flight on a particular day faster than average won't help much to reduce costs, as the airline has to compute flight schedules weeks or months in advance, so they have to calculate average boarding times for a particular aircraft, and factor that into schedules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airlines could bring the average boarding time down, they could fit more flights, tighten up the timing of legs and itineraries, and lower the asset-hour per passenger-hour ratio, which would result in aggregate cost savings in gate costs, personnel costs, fuel, insurance, and financing costs.&lt;/p&gt;&#xA;" OwnerUserId="9782" LastActivityDate="2015-08-12T22:08:53.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18832" PostTypeId="1" CreationDate="2015-08-12T23:21:16.137" Score="6" ViewCount="640" Body="&lt;p&gt;In my experience with general aviation twin-engine turboprops I've never heard of one with counter rotating propellors. I've never seen any data about an engine manufacturer building left-rotating turboprop engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also curious if any counter rotating twin-engine turboprop aircraft exist outside general aviation as well.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-13T01:00:09.530" LastActivityDate="2015-08-13T01:14:08.993" Title="Has a general aviation twin-engine turboprop with counter rotating propellors ever been built?" Tags="&lt;general-aviation&gt;&lt;propeller&gt;&lt;turboprop&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18833" PostTypeId="2" ParentId="18783" CreationDate="2015-08-12T23:37:25.407" Score="0" Body="&lt;p&gt;In order to answer this question the terminology and procedures must be clarified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airplane is in the airport traffic pattern and the runway won't be available by the time by the time it would reach it, the airplane can extend the traffic pattern to give the runway time to be available for landing. If it's going to take 20 minutes the airplane would need to depart the pattern and return later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of the word hold is out of context here. As defined by the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot; rel=&quot;nofollow&quot;&gt;Instrument Flying Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Holding is a predetermined maneuver which keeps aircraft within a specified airspace while awaiting further clearance from ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The way the question is asked it reveals that the person asking assumes that a hold is something performed in an airport traffic pattern, but it is not. A hold would be used at an enroute altitude and outside the immediate terminal aerodrome environment where traffic patterns are flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a runway were unavailable for 20 minutes and an airplane were enroute on an IFR flight plan, ATC might issue that airplane a hold which is published on an instrument approach procedure for that airport. The airplane might hold there for 20 minutes until the runway became available again. This scenario would happen before the airplane reached the traffic pattern or after it departed it.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-12T23:37:25.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18834" PostTypeId="1" CreationDate="2015-08-13T00:35:22.013" Score="8" ViewCount="456" Body="&lt;p&gt;For large, busy airports (such as JFK), how do they measure how well they are being utilized? I assume airport management wants to serve as many flights as possible, for maximum revenue. Any time their gates are empty, or runways aren't being utilized, the airport has more capacity to sell. Is there some sort of industry standard measurement for &quot;airport utilization efficiency&quot;?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-13T19:13:13.480" Title="Is there an efficiency measure for airports?" Tags="&lt;airport&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18835" PostTypeId="2" ParentId="18832" CreationDate="2015-08-13T01:14:08.993" Score="8" Body="&lt;p&gt;The only aircraft with turboprop counter rotating propellers that I can think of is the Piaggio P 180 &lt;em&gt;Avanti&lt;/em&gt;, whose design is unusual in so many ways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check out &lt;a href=&quot;http://www.mpa.piaggioaerospace.it/&quot;&gt;http://www.mpa.piaggioaerospace.it/&lt;/a&gt;, which gives the specifications of a Maritime Patrol Aircraft(MPA) based on the P 180.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-13T01:14:08.993" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18836" PostTypeId="2" ParentId="18834" CreationDate="2015-08-13T01:25:33.207" Score="3" Body="&lt;p&gt;The Air Transport Research Society (ATRS) has a benchmarking system for determining the efficiency of the airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically,it takes the airport size and related infrastructure (runways, no. of gates etc.) as inputs and measures the airport efficiency in terms of aircraft and passenger movement,revenue etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a yearly &lt;a href=&quot;http://www.atrsworld.org/index.html&quot; rel=&quot;nofollow&quot;&gt;Global Airport Benchmarking Report&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="65" LastEditDate="2015-08-13T19:13:13.480" LastActivityDate="2015-08-13T19:13:13.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18837" PostTypeId="1" CreationDate="2015-08-13T01:47:23.473" Score="8" ViewCount="857" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/1753/why-arent-bird-radars-placed-on-the-front-of-commercial-aircraft&quot;&gt;a related question&lt;/a&gt;, I got to thinking about bird strikes again and the fact that they are sucked into the engine at great velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot had 5 to 10 seconds of warning time, would throttling down the engines to idle be a good idea? Would it save those engines even if a bird hit the intake fan? This would of course be a temporary measure, intended to prevent the birds being sucked in harder or faster than otherwise. Once the birds passed, the engines would be throttled up again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking about large commercial jets like the Airbus A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: one concern I have is that at high throttle, the engine will &lt;strong&gt;suck in objects from a wider area than just the engine inlet&lt;/strong&gt;. Is this assumption true?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3386" LastEditDate="2017-11-14T19:45:55.947" LastActivityDate="2018-05-29T06:18:44.273" Title="Can bird strikes be dealt with by throttling down engines to idle?" Tags="&lt;safety&gt;&lt;jet-engine&gt;&lt;bird-strike&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18838" PostTypeId="1" AcceptedAnswerId="18863" CreationDate="2015-08-13T02:01:40.590" Score="5" ViewCount="1187" Body="&lt;p&gt;I've read that there are several ways a CFI can renew their FAA instructor certificate. What ways are available for a CFI to renew?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-13T17:14:23.260" LastActivityDate="2015-08-13T18:05:12.930" Title="How can a CFI renew their certificate with the FAA?" Tags="&lt;faa-regulations&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18839" PostTypeId="1" AcceptedAnswerId="18842" CreationDate="2015-08-13T02:05:11.687" Score="7" ViewCount="8128" Body="&lt;p&gt;What is a gold seal flight instructor and how does it differ from a usual flight instructor? Does it offer any additional privileges or prestige?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="14957" LastEditDate="2021-04-27T17:45:19.577" LastActivityDate="2021-04-27T17:45:19.577" Title="What is a gold seal flight instructor?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18840" PostTypeId="2" ParentId="18837" CreationDate="2015-08-13T02:27:20.770" Score="7" Body="&lt;p&gt;&quot;would throttling down the engines to idle be a good idea?&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Probably not, 3 reasons I can think of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing speeds for an Airbus A320 (your example) will typically be in the region of 130kt to 140kt faster then the cruise speed of many GA aircraft. Even at those speeds, a bird strike is likely to have a significant impact on anything it hits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The published minimum speed of the high pressure compressor/turbine spool is 66% of the rated maximum. Since the max turbine speed is VERY fast think 20-30k RPM, 66% of it is probably enough to cause any damage that would occur with a normal strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the unlikely even you see the birds with more than 2-3s to react (there very hard to spot at high speeds), you would more likely want to INCREASE thrust to A) try to outmaneuver the bird and B) in case of an engine failure the other would already be running near the power required for continued flight on one engine (essential since most bird strikes are at lower altitudes where you may not have enough altitude to reduce power for 10s or so then power back up to max thrust taking another few seconds)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: an argument could be made for not touching the throttles at all until you can total verify one or more engines have failed based on the number of pilots, who in a panic manage to turn off the wrong engine during an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note. referenced speeds are approximate I would welcome edits with more specific data.&lt;/p&gt;&#xA;" OwnerUserId="9318" LastEditorUserId="9318" LastEditDate="2018-05-29T06:18:44.273" LastActivityDate="2018-05-29T06:18:44.273" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="18841" PostTypeId="2" ParentId="18837" CreationDate="2015-08-13T02:31:08.747" Score="8" Body="&lt;p&gt;In general, greater the engine thrust, greater the damage caused due to the bird strike. This is to both the higher speed of the compressor blades and the pressure ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it makes sense if the pilot can throttle down the engines if bird strike is imminent. In fact, approaching in idle condition is on of the strategies for reducing the possibility of bird strikes. See &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/&quot;&gt;http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/&lt;/a&gt; and &lt;a href=&quot;http://www.skybrary.aero/index.php/Bird_Strike_on_Final_Approach:_Guidance_for_Flight_Crews&quot;&gt;http://www.skybrary.aero/index.php/Bird_Strike_on_Final_Approach:_Guidance_for_Flight_Crews&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are other things to consider. For example, most of the bird strikes happen during take off and landing and it is not advisable to throttle back the engines at that point of time (it is one thing to descend in idle power and another to reduce power during landing). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, given the speed of the aircraft and the size of the birds, it is unlikely that the pilot will have enough warning unless he's approaching a huge flock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is, given that the velocity of bird strike is a function of both aircraft speed and compressor speed, reducing to idle power won't prevent damage due to bird strike as the compressor rotates at a very high speed even in idle condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, modern engines are designed to operate (or fail safely) in the event of bird ingestion and it is far better to continue the flight and take appropriate action like go around and land.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-13T02:31:08.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18842" PostTypeId="2" ParentId="18839" CreationDate="2015-08-13T02:44:36.113" Score="9" Body="&lt;p&gt;A gold seal flight instructor is obtained by having a ground instructor certificate and within the previous 24 months have a pass/fail rate of 80% or above and recommending at least 10 applicants. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a way for the FAA to recognize the best instructors in the industry.  You do not get any special privileges with the gold seal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_61-65e.pdf&quot;&gt;AC 61-65&lt;/a&gt; for more details.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-08-13T02:44:36.113" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18843" PostTypeId="1" AcceptedAnswerId="18846" CreationDate="2015-08-13T02:46:16.467" Score="18" ViewCount="8507" Body="&lt;p&gt;What does it mean if an airplane uses the &quot;super&quot; designation after their call sign on the radio?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="3825" LastEditDate="2015-08-13T03:36:37.523" LastActivityDate="2015-08-13T15:36:47.510" Title="What does it mean when an airplane has the &quot;super&quot; call sign?" Tags="&lt;radio-communications&gt;&lt;wake-turbulence&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ClosedDate="2015-08-14T18:54:13.163" ContentLicense="CC BY-SA 3.0" />
  <row Id="18844" PostTypeId="1" CreationDate="2015-08-13T02:50:08.550" Score="4" ViewCount="1877" Body="&lt;p&gt;In discussions about TCAS I've overheard mentioning different levels such as &quot;TCAS 1&quot; or &quot;TCAS 3.&quot; What are the different types of TCAS and how are they different?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-13T14:21:03.840" Title="What are the differences between the different types of TCAS?" Tags="&lt;safety&gt;&lt;avionics&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18845" PostTypeId="2" ParentId="18843" CreationDate="2015-08-13T03:19:21.750" Score="11" Body="&lt;p&gt;The aircraft is either an A380, or AN225. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/7110.691.pdf&quot;&gt;Reference&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-08-13T03:19:21.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18846" PostTypeId="2" ParentId="18843" CreationDate="2015-08-13T03:21:33.587" Score="26" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.icao.int/meetings/anconf12/workingpapers/anconfwp41.2.1.en.pdf&quot;&gt;ICAO wake turbulence categories&lt;/a&gt;, it is a super-heavy aircraft capable of generating correspondingly super-strong wake vortices. Currently &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.626.pdf&quot;&gt;the only &quot;super&quot; aircraft&lt;/a&gt; are the &lt;strong&gt;Airbus A380&lt;/strong&gt; and &lt;strong&gt;Antonov An-225&lt;/strong&gt; (FAA). &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-08-13T15:36:47.510" LastActivityDate="2015-08-13T15:36:47.510" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18847" PostTypeId="1" CreationDate="2015-08-13T03:32:54.377" Score="12" ViewCount="3501" Body="&lt;p&gt;It is said that given roughly similar aerodynamic and engine technology that twin engine airliners are more fuel efficient than 3 or 4 engine airliners.  Why is this?  The twin engine airliners tend to have more excess power so I'm thinking that they can climb faster and fly higher, lowering the amount of time spent climbing (uses more fuel than cruise) and lowering fuel consumption during cruise.  I suppose that fuel consumption is less while the engines are idling as well.  Are there other factors that go into the 2 vs 3 vs 4 engine fuel consumption issue?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-10-03T15:56:22.983" Title="Why are twin engine airliners more fuel efficient than three or four engine airliners?" Tags="&lt;jet-engine&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18848" PostTypeId="2" ParentId="18847" CreationDate="2015-08-13T04:07:26.077" Score="3" Body="&lt;p&gt;I'm not sure if the twin engined aicraft are more fuel effecient compared to their four engined counterparts. Is there any hard data available?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, newer aircraft are more fuel effecient compared to older ones. See &lt;a href=&quot;http://www.transportenvironment.org/sites/te/files/media/2005-12_nlr_aviation_fuel_efficiency.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.transportenvironment.org/sites/te/files/media/2005-12_nlr_aviation_fuel_efficiency.pdf&lt;/a&gt;. For example, the Boeing 747-8 first flown in 2011 is more fuel efficient compared to the 787-8 which flew first in 2009 while being less efficient compared to 787-9 (which flew in 2013). It is instructive to note that the 747-8 uses the same engines as 787-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can say the twinjets are more efficient because of the engines used in them. Almost all the aircraft under development are twinjets, with the A380 being the last 4 engine aircraft to enter (commercial) service. These aircraft incorporate a number of recent advances in the field (like increased use of composites along with better engines), which makes them more fuel efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, there is no reason to say that twinjets &lt;em&gt;will&lt;/em&gt; be more efficient than four engines aircraft, but are usually so because of various other developments, which are also equally applicable to the four engined types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: See the References given in &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft&lt;/a&gt; for comparison of fuel effeciencies of aircrafts.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="595" LastEditDate="2015-08-13T07:12:47.683" LastActivityDate="2015-08-13T07:12:47.683" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18849" PostTypeId="1" AcceptedAnswerId="18923" CreationDate="2015-08-13T04:30:17.017" Score="10" ViewCount="1831" Body="&lt;p&gt;Let's say someone has bought one of those &lt;a href=&quot;http://www.dji.com/product/phantom-2-vision&quot;&gt;quad copter camera UAVs&lt;/a&gt; and wasn't completely aware of FAA rules regarding airspace and where they can fly their drone, etc.  Then let's say that they flew it into the airspace of a Class B airport by accident.&lt;sup&gt;1&lt;/sup&gt;  What would happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume the airport, if they knew about it, would shut down the airspace until the drone had cleared (&lt;a href=&quot;http://ktla.com/2015/06/25/illegal-4-foot-drone-shut-down-aerial-firefight-over-lake-fire-forest-service/&quot;&gt;kind of like that recent fire&lt;/a&gt;.)  But after that, what happens?  Does the FAA have a way to figure out who was flying the drone?  And even if they do figure it out, is their an FAA based penalty for flying into controlled airspace with an unauthorized drone?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;  &lt;em&gt;Here's an example of a Class B airport, for anyone who isn't sure what that is: &lt;a href=&quot;https://en.wikipedia.org/wiki/Lambert%E2%80%93St._Louis_International_Airport&quot;&gt;Lambert-St. Louis International&lt;/a&gt;.  So, basically, a really&lt;/em&gt; big &lt;em&gt;airport.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;For those who seem to think this question is a dupe of &quot;Is it legal to fly a Quadrocopter/Drone into an Airport?  What will happen?&quot;:  The only fragments that kind of deal with my question are as thus:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From dvnrrs regarding legal action:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Were you to actually fly it over the fence, you could be charged with&#xA;  trespassing. If you had any intent to cause harm, other charges might&#xA;  apply (up to attempted murder if you were trying to bring down an&#xA;  airliner).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;From ratchet freak regarding what the airport might do:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the tower sees unauthorized entry of a drone they will clear the&#xA;  airspace and send security to catch the guy controlling it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Both of these comments lack detail, and that's probably because both of those snippets are from answers that were mostly dealing with the safety aspects of the question rather than with the legal aspects (eg., could a drone actually cause damage).  I am after the legal aspect, and I am looking for more detail than &quot;It's not legal, you may get charged&quot; plus &quot;they'll send security.&quot;&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;CGCampbell did start down that road by listing a statute that contains more detailed rules about what you can do, but it doesn't say what will happen if you don't follow said rules.&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I want to know what laws the FAA will use to prosecute, how they will track down the perpertrator and, lastly, what evidence they will need to either fine or charge them with a crime.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2015-08-14T21:32:28.870" LastActivityDate="2015-08-16T16:17:03.907" Title="What legal actions would be taken against a drone pilot if they flew a drone into class B airspace?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18850" PostTypeId="2" ParentId="18844" CreationDate="2015-08-13T04:59:54.520" Score="4" Body="&lt;p&gt;The Traffic Collision Avoidance System TCAS (also called ACAS - Automated Collision Avoidance System) is used in aircraft to alert the pilots about possible collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic system in all the levels are the same. &lt;a href=&quot;https://aviation.stackexchange.com/questions/1883/how-does-tcas-work&quot;&gt;As per the FAA&lt;/a&gt; what differs is the type of warning issued to the pilots. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/TCAS%20II%20V7.1%20Intro%20booklet.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;As per FAA&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TCAS is a family of airborne devices that function independently of the ground-based air traffic control (ATC) system, and provide collision avoidance protection for a broad spectrum of aircraft types.  All TCAS &#xA;  systems provide some degree of collision threat alerting, and a traffic display.  TCAS I and II differ primarily by their alerting capability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS I&lt;/strong&gt; issues 'traffic advisories' (TAs) to the pilot, alerting him to the impending collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS II&lt;/strong&gt; provides the pilots with resolution advisories(RAs) in addition to TAs. Basically the TCAS provides the pilot with the required escape manevores in th &lt;em&gt;vertical&lt;/em&gt; direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TCAS III and IV&lt;/strong&gt; were supposed to provide &lt;em&gt;horizontal&lt;/em&gt; resolution RAs, but development was stopped due to &lt;a href=&quot;http://yarchive.net/air/airliners/tcas.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;limitations of the available TCAS antennae&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS is expected to be replaced by automatic dependent surveillance – broadcast (ADS–B)&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-13T14:21:03.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18851" PostTypeId="2" ParentId="18847" CreationDate="2015-08-13T05:01:34.310" Score="6" Body="&lt;p&gt;Not a fully definitive answer, but a large part of the &quot;efficiency&quot; of an aircraft is drag and weight. Two (larger) round engines will have less surface causing drag than four smaller ones. In addition, each engine will add complexity to the aircraft (fire monitors, fuel piping, extra hydraulics) as well as necessitating duplication of things like thrust reverses, all of which add extra weight and sometimes drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, all things being equal, one huge engine would be most &quot;efficient&quot;. This would obviously be difficult, and impractical for most passenger jets, so when they will fit, without scraping the ground, two are used. If more thrust is needed, then they break it down into three or four.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note, the main reason 4 engines were used in the first place was for redundancy. At least one country's [US?] regulations stated that the aircraft must be capable of sustained flight, including climbing, with the loss of an engine. 2-1 = 50% thrust lost where as 4-1= only 25% loss, therefore requiring less reserve power)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Edit note #2 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Twin engine airliners tend to have more excess power&quot; they climb faster may be relevant in terms of efficiency, but part of the reason a twin will usually have more reserve thrust is due to the redundancy &quot;keep flying&quot; rules described above. &lt;/p&gt;&#xA;" OwnerUserId="9318" LastEditorUserId="595" LastEditDate="2015-08-13T07:11:44.590" LastActivityDate="2015-08-13T07:11:44.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18852" PostTypeId="2" ParentId="14038" CreationDate="2015-08-13T07:08:38.940" Score="0" Body="&lt;p&gt;Detonation is the instaneous combustion that occur due to unburnt gases left in the combustion chamber resulting in high temperature, sufficient for self-ignition&lt;/p&gt;&#xA;" OwnerUserId="9784" LastEditorUserId="1467" LastEditDate="2015-08-13T07:25:35.070" LastActivityDate="2015-08-13T07:25:35.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18854" PostTypeId="2" ParentId="18837" CreationDate="2015-08-13T10:22:15.280" Score="3" Body="&lt;p&gt;To answer your question &quot;Can they be dealt with&quot;, I think throttling down is nowhere near a total solution, although it might have a small effect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big problem is that the aircraft is typically flying at a speed of between 130 and 250 knots towards the birds. The engines don't suck the birds in (because there is relatively little time for this to have an effect) the birds just get in the way of the engines and the impact forces of a 10 lb bird doing between 130 and 250 knots (relatively) do the damage.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-08-13T19:27:42.730" LastActivityDate="2015-08-13T19:27:42.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18855" PostTypeId="2" ParentId="18837" CreationDate="2015-08-13T11:32:17.057" Score="18" Body="&lt;p&gt;A goose can easily be flying at 40mph and a commercial jet will be landing at about 150mph, giving a closing speed of about 190mph (305km/h). That means that, to spot a goose with 10s warning, you would need to spot it when it's more than half a mile away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not only would you have to spot that tiny speck of a goose half a mile away during the busiest phase of the whole flight, but you'd also have to immediately work out whether the tiny speck was even coming towards you. If it was, you'd have to estimate whether it would even hit the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, supposing you'd immediately and accurately recognized the danger to your plane from that tiny speck, you'd have to immediately reduce power to the engines, while being very careful not to hit the ground the bad way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, regardless of how much better the outcome of a bird hitting an idling engine would be than one hitting an engine under power, it's just not feasible to try to power down the engines. Once you take into account the false alarms, which would vastly outnumber the actual bird strikes, trying to power down the engines would probably be far more dangerous than just hitting the bird.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-08-13T11:32:17.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18856" PostTypeId="1" CreationDate="2015-08-13T13:05:58.827" Score="3" ViewCount="156" Body="&lt;p&gt;Not being a pilot, learned about the &lt;a href=&quot;http://asrs.arc.nasa.gov/&quot; rel=&quot;nofollow&quot;&gt;ASRS&lt;/a&gt; from this site. Have any aviation safety authorities in other countries attempted to emulate the ASRS and to what degree was it successful? After all it was introduced in 1976, which is quite a while ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly interested in European airspace, although examples from other countries/regions are welcome.&lt;/p&gt;&#xA;" OwnerUserId="337" LastActivityDate="2015-08-14T12:36:43.863" Title="Does EASA (or other regional/national aviation safety authority) have a confidential &quot;close-call&quot; reporting system?" Tags="&lt;safety&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18858" PostTypeId="1" AcceptedAnswerId="18883" CreationDate="2015-08-13T15:59:37.877" Score="7" ViewCount="2925" Body="&lt;p&gt;In this &lt;a href=&quot;https://youtu.be/5GKCu_J73Kk?t=10m35s&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; (minutes from 10:46 to 11:00), the spoilers seem to be slightly deployed during take off. What's the purpose of this? I've already seen this in other videos too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also read the answers to the question &lt;a href=&quot;https://aviation.stackexchange.com/questions/1955/when-can-spoilers-be-used-on-airliners&quot;&gt;When can spoilers be used on airliners&lt;/a&gt;, but they seem to be related to slowing down the aircraft or for descending faster. But what is the point during take off, when it's supposed the pilots want to climb and go faster?&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-08-14T05:14:51.967" Title="Why do spoilers seem to be slightly activated during take off?" Tags="&lt;spoilers&gt;" AnswerCount="4" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="18859" PostTypeId="1" AcceptedAnswerId="18862" CreationDate="2015-08-13T16:21:15.030" Score="23" ViewCount="9499" Body="&lt;p&gt;I was reading &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.23#se14.1.23_13&quot;&gt;14 CFR 23.3&lt;/a&gt;, which discusses airplane categories. In normal and commuter categories, stalls (except whip stalls) are allowed. The regulation, however does not define &quot;whip stalls.&quot; What is meant by this term?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1696" LastEditDate="2015-08-13T16:46:00.153" LastActivityDate="2020-11-18T15:50:10.397" Title="What is a whip stall?" Tags="&lt;aircraft-performance&gt;&lt;stall&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18860" PostTypeId="1" AcceptedAnswerId="18866" CreationDate="2015-08-13T16:38:25.667" Score="2" ViewCount="721" Body="&lt;p&gt;Since the standard A330's nose-down body angle on the ground, the A330F uses a revised nose undercarriage layout to provide a level deck during cargo loading to overcome the issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the angle between A330 body and the ground?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="1696" LastEditDate="2015-08-13T16:45:00.310" LastActivityDate="2015-08-13T22:23:34.947" Title="What is the angle between A330 body and the ground?" Tags="&lt;airbus-a330&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18862" PostTypeId="2" ParentId="18859" CreationDate="2015-08-13T16:47:45.747" Score="14" Body="&lt;p&gt;The clearest definition I could find is from &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2000/December/1/Test-Pilot-%2812%29&quot;&gt;an AOPA quiz&lt;/a&gt; (of all places):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane is pitched up into a vertical or near-vertical climb. It&#xA;  then pauses, slips downward momentarily (tail first), and then whips&#xA;  into a steep, nose-down attitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The tail-first slip backwards seems to be the defining characteristic of a whip stall. Interestingly, &lt;em&gt;Whip Stall and Tumble Awareness&lt;/em&gt; is included in the &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-32.pdf&quot;&gt;FAA's Powered Parachute and Weight Shift Control PTS&lt;/a&gt;, but they aren't defined there either.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-13T16:47:45.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18863" PostTypeId="2" ParentId="18838" CreationDate="2015-08-13T17:43:40.873" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1197&quot;&gt;14 CFR 61.197&lt;/a&gt; lists renewal requirements for flight instructors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your CFI certificate is still valid (unexpired) than you can renew by any one of the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Getting a new rating on your CFI certificate or re-taking a practical test for an existing rating on your CFI certificate&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Passing a practical test for—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) One of the ratings listed on the current flight instructor certificate; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) An additional flight instructor rating; or&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;Having had at least 5 students in the last 2 years with an 80% or higher pass rate &#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(i) A record of training students showing that, during the preceding 24 calendar months, the flight instructor has endorsed at least 5 students for a practical test for a certificate or rating and at least 80 percent of those students passed that test on the first attempt.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;Being a check pilot, chief flight instructor, check airman or flight instructor for a part 121 or 135 operation and active in pilot evaluation during the last 2 years&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(ii) A record showing that, within the preceding 24 calendar months, the flight instructor has served as a company check pilot, chief flight instructor, company check airman, or flight instructor in a part 121 or part 135 operation, or in a position involving the regular evaluation of pilots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;Completing an approved refresher course within the preceding 3 months&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) A graduation certificate showing that, within the preceding 3 calendar months, the person has successfully completed an approved flight instructor refresher course consisting of ground training or flight training, or a combination of both.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;Passing a US armed forces military instructor proficiency check in the preceding 12 months.&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iv) A record showing that, within the preceding 12 months from the month of application, the flight instructor passed an official U.S. Armed Forces military instructor pilot proficiency check.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you are not actively instructing and just maintaining your certificate the easiest method is the approved refresher course.  There are a few weekend workshops and a online courses that are approved.  The last time I did this method I used an online course and submitted the 8710 via IACRA and completed the whole thing over a weekend and with no physical paperwork.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your certificate has expired, even if you have completed the above but failed to submit the proper paperwork in time, then you can no longer do this the easy way and have to look at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1199&quot;&gt;14 CFR 61.199&lt;/a&gt;.  To reinstate an expired certificate you must either pass a practical test for one of your existing CFI ratings or pass a practical test for a new rating for your CFI certificate.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-08-13T18:05:12.930" LastActivityDate="2015-08-13T18:05:12.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18864" PostTypeId="2" ParentId="18858" CreationDate="2015-08-13T18:07:21.560" Score="2" Body="&lt;p&gt;Large jet aircraft have multi function spoilers. They aide in turning the aircraft at low speed. When the aircraft needs to be slowed down in the air and on landing all of the spoilers are activated.&lt;/p&gt;&#xA;" OwnerUserId="9766" LastActivityDate="2015-08-13T18:07:21.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18865" PostTypeId="1" CreationDate="2015-08-13T18:09:14.950" Score="39" ViewCount="17373" Body="&lt;p&gt;(this seems to be primarily a US phenomenon)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in the vicinity of my parents' place (in a rural area in Indiana), there are several registered airports within several miles' radius.  I remember when I was a kid, there were a few farmers in the area who liked to fly ultralights, and I wonder if some of these might be for that.  And some of these are listed as having certain aircraft based there.  For many of them, however, looking at their fields on Google Maps there is nothing to indicate that it is ever used for anything but growing crops--in some places there is no obstacle-free area even reasonably close to the listed runway dimensions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's going on here?&lt;/p&gt;&#xA;" OwnerUserId="9790" LastEditorUserId="19" LastEditDate="2017-03-27T08:29:33.227" LastActivityDate="2019-03-22T13:12:41.160" Title="Why do farmers register their fields as airports?" Tags="&lt;airport-design&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18866" PostTypeId="2" ParentId="18860" CreationDate="2015-08-13T18:35:56.360" Score="4" Body="&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; The angle is about 1 degree.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best reference I can think of is the &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A330-20140101.pdf&quot; rel=&quot;nofollow&quot;&gt;aircraft characteristics document provided by Airbus&lt;/a&gt;. This provides key dimensions for the A330 family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I looked at the dimensions for the forward and aft lower deck cargo doors. The document provides both the distance from the ground to the floor of the hold (§2-3-0), and to the door center from the nose (§2-7-0). With this information, an inverse tangent will give the angle of the deck between the doors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two factors that affect these numbers. First, the three models of aircraft have different measurements. The other factor is weight and balance of the aircraft, which affects how much the suspension on each gear is compressed. A heavier aircraft will sit lower to the ground, and the location of the center of gravity will affect how much weight is resting on each landing gear position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Calculating the angles gives the following angles. Note the larger angle on the shorter -200, and the difference of about a degree between the values on the -200 and the freighter -200F.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although 1 degree may not seem like much, note the difference of about 33 cm (13 in.) height between the -200 and the -200F at the forward cargo door. This is near the nose gear, which is the reason that modifications were necessary to fit the extra nose gear length in the gear bay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;-300&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;176,000 kg, CG 26.8%: 1.2 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 15%: 1.1 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 36.5%: 0.8 deg&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;-200&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;119,000 kg, mid CG: 1.4 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 21%: 1.3 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 37.5%: 0.8 deg&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;-200F&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;115,000 kg, CG 20%: 0.4 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 20.6%: 0.2 deg&lt;/li&gt;&#xA;&lt;li&gt;MRW, CG 37.4%: 0 deg&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-08-13T22:23:34.947" LastActivityDate="2015-08-13T22:23:34.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18867" PostTypeId="2" ParentId="18865" CreationDate="2015-08-13T18:42:33.517" Score="36" Body="&lt;p&gt;Private airfields are not at all uncommon in the U.S., especially the rural parts (which is most of the U.S.) These are probably for crop dusting or because the owner also happens to be a private pilot and wants to keep their plane at home rather than paying the local FBO for hangar or tie-down rental. Of the ones I've seen, though, the markings vary from very simple (old tires painted white placed along the edges) to non-existent. Sometimes smaller ones can be hard to see on Google Maps, but, at least in my experience, you can usually find them if you look hard enough. They're probably easier to spot in places with a lot of trees rather than in places where the land is predominately wide-open farmland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example of what it looks like on a Sectional Chart and on Google Maps:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aSygR.jpg&quot; alt=&quot;Sectional Chart Showing Private Airfields&quot;&gt;&lt;br&gt;&#xA;One Grand Field on a Sectional Chart&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/M3TrT.png&quot; alt=&quot;One Grand Field (yes, it&amp;#39;s really a field.)&quot;&gt;&lt;br&gt;&#xA;One Grand Field (yes, it's literally a field) on Google Maps. The long, narrow clearing in the trees is the grass runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To give an idea of just how common these things can be, take a look at this sectional chart clip:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nUi2r.jpg&quot; alt=&quot;Atlanta North Sectional Chart showing lots of private airfields&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no less than 12 private airports here within a roughly 25 nmi x 25 nmi area, despite having two nearby decent-sized public uncontrolled airfields (one of which is home to a large flight training school,) and a class D airport (with a busy-ish Class C visible in the Northwest corner of the clip.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-13T19:21:39.727" LastActivityDate="2015-08-13T19:21:39.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18868" PostTypeId="2" ParentId="18865" CreationDate="2015-08-13T18:43:22.037" Score="21" Body="&lt;p&gt;They may have crop-dusters that they fly in and out of their own fields like this one. If the crops need dusting often and there is no airport nearby it may be cheaper and easier to fly from their own fields rather than spend the gas getting back and forth to a local field.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2001/March/200103_Features_Private_Airports.html&quot; rel=&quot;noreferrer&quot;&gt;great little article&lt;/a&gt; that may give you some info. As to why they have them on the chart the article states, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So, if private airports are so private, why do their owners choose to have them depicted on sectional charts? Again, the reasons vary, but most owners seem to be motivated by altruism. Pilots want other pilots to have options when they fly, especially in the event of an emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pwrsO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pwrsO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="938" LastEditDate="2015-08-14T04:39:06.283" LastActivityDate="2015-08-14T04:39:06.283" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="18869" PostTypeId="1" CreationDate="2015-08-13T18:46:16.450" Score="9" ViewCount="6846" Body="&lt;p&gt;Per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1129&quot;&gt;14 CFR 61.129&lt;/a&gt;, a person who applies for a commercial pilot certificate for airplanes (both single and multiengine) must log at least ten hours of instrument training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming a pilot obtains their instrument rating prior to training for their commercial pilot certificate, can the instrument time logged during training for an instrument rating be used to satisfy this requirement (assuming class of aircraft requirements are met)?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2018-07-13T00:57:44.947" Title="Can training for an Instrument Rating be applied towards a commercial pilot certificate?" Tags="&lt;faa-regulations&gt;&lt;far-61&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18870" PostTypeId="2" ParentId="11818" CreationDate="2015-08-13T20:15:15.907" Score="3" Body="&lt;p&gt;I also found this &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20081002183543AAvbpDy&quot; rel=&quot;nofollow noreferrer&quot;&gt;answer&lt;/a&gt; from this user &lt;a href=&quot;https://answers.yahoo.com/activity/questions?show=3A2IF6ZT5KHMVDPTWXLUS2EMNY&amp;amp;t=g&quot; rel=&quot;nofollow noreferrer&quot;&gt;cougar531&lt;/a&gt; on Yahoo!Answers. It sounds very helpful; something I'll try on my next flight. I also have the same problem, hence my id.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Assuming you've made a stabilized approach (constant airspeed, stable rate of descent, and without the need for major control inputs) then the flare is just a matter of practice. I imagine as you get close to the runway (say roughly the same height above ground as a hangar roof) you will gradually reduce power to idle and pitch up from your nose-low approach attitude to a more nose-level attitude. This is often called the round-out and immediately precedes the flare. When I talk about a flare I am assuming you are already just a few feet above ground.&lt;/p&gt;&#xA;&lt;p&gt;The flare, as you correctly stated, is the time when you gradually pitch up as the aircraft slows without climbing (ballooning). The purpose is to slow the airplane down and touchdown at the slowest possible speed. The difficulty you have with making the flare without ballooning is very common, and no matter what it will take practice. The best way to practice this is to sharpen your sense of vertical movement while landing. I recommend looking further down the runway--toward the horizon, and be aware of cues in your peripheral vision that your airplane is sinking or rising. Your peripheral vision is particularly useful when the aircraft nose blocks the horizon. Pay attention, and over time you will develop a feel for the aircraft's sink-rate.&lt;/p&gt;&#xA;&lt;p&gt;In the flare you should increase pitch to keep the airplane barely sinking toward the ground--we're talking almost level. As the airplane slows in airspeed you will feel it sink. Increase pitch to all-but-stop the sinking. If you increase the pitch to the point where the airplane completely stops descending, then hold that pitch where it is until the airplane starts to sink again. If you pitch up too rapidly and the airplane starts to balloon, your best bet is usually a go-around, although very very slight balloons can sometimes be corrected by simply holding the pitch and waiting for more speed to bleed off and the airplane to sink again. In all cases, resist the urge to lower the pitch of the nose. Your airplane is still slowing down on its own, and lowering the nose will kill what little lift you have left and could set you on the pavement pretty hard.&lt;/p&gt;&#xA;&lt;p&gt;The rate at which you'll have to pitch up in the flare will vary depending on the day, the weight of the airplane, your airspeed, winds, etc... Some days it will be very fluid and gradual, and on other days you may find yourself having to make a few quick pitch adjustments. But if you try to make your adjustments in response to how rapidly the aircraft is sinking toward the ground based on visual cues out the window, then you should have good luck.&lt;/p&gt;&#xA;&lt;p&gt;Remember you a trying to control a one ton piece of aluminum flying at 50 mph within the precision of a few inches... it definitely takes practice! Have fun and good luck!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9783" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-13T20:15:15.907" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18871" PostTypeId="1" AcceptedAnswerId="18873" CreationDate="2015-08-13T20:19:46.287" Score="7" ViewCount="5655" Body="&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/2620/how-does-ils-instrument-landing-system-work&quot;&gt;Instrument Landing System&lt;/a&gt; and some others systems can provide to incoming aircraft guidance to the runway in poor visibility scenarios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in mind, I have these questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can helicopters fly in IMC?&lt;/li&gt;&#xA;&lt;li&gt;Is there any system that can help the pilot land, just like ILS?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2018-03-19T17:46:31.953" Title="Can helicopters land in a poor visibility scenario?" Tags="&lt;landing&gt;&lt;helicopter&gt;&lt;flight-instruments&gt;" AnswerCount="4" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="18872" PostTypeId="2" ParentId="18871" CreationDate="2015-08-13T20:40:02.603" Score="6" Body="&lt;p&gt;Helicopters can fly IFR and they fly the same approaches airplanes do.  At certain airports there will be ILS (or other approach) procedures specific to helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vXqzh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vXqzh.png&quot; alt=&quot;![enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between the above procedure and the normal ILS 4L is that the copter approach has lower minimums, allowing the helicopters to land in lower visibility than airplanes.  At airports without specific approaches for helicopters, they would fly the same procedures airplanes do.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-08-13T20:40:02.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18873" PostTypeId="2" ParentId="18871" CreationDate="2015-08-13T20:40:14.513" Score="7" Body="&lt;p&gt;Can helicopters fly IFR?  &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_7.pdf&quot; rel=&quot;nofollow&quot;&gt;Yes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they use ILS?  &lt;a href=&quot;https://www.youtube.com/watch?v=ZxKFvcCYRI4&quot; rel=&quot;nofollow&quot;&gt;Yes&lt;/a&gt;.  The only tricky part of it is the need to be slow at the end of the glide slope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An IFR helicopter can use any of the navigation and landing aids available to any other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-161354.html&quot; rel=&quot;nofollow&quot;&gt;PPRuNe discussion&lt;/a&gt; is interesting.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-08-14T06:50:54.390" LastActivityDate="2015-08-14T06:50:54.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18874" PostTypeId="1" CreationDate="2015-08-13T21:24:41.237" Score="9" ViewCount="10255" Body="&lt;p&gt;Is there any regulation that prohibits passengers from using a cabin jumpseat (normally used by cabin crew) if there is no passenger seat available? Like the two shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, can any of the cabin jumpseats be sold? (Given that cabin members are fewer than the available jumpseats of course.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XLZP4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XLZP4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A32X_Forward_Attendant_Station.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="9791" LastEditorUserId="14897" LastEditDate="2017-08-05T04:11:02.570" LastActivityDate="2017-08-05T07:05:33.303" Title="Can a paying passenger ride in one of the cabin jumpseats?" Tags="&lt;faa-regulations&gt;&lt;flight-attendant&gt;&lt;seats&gt;&lt;cabin&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18875" PostTypeId="1" AcceptedAnswerId="18964" CreationDate="2015-08-13T23:09:01.630" Score="10" ViewCount="784" Body="&lt;p&gt;Why is there no helicopter equivalent to air transport CAT III ILS?  &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-161354.html&quot; rel=&quot;noreferrer&quot;&gt;This PPrUNe&lt;/a&gt; thread discusses that some helicopter manufacturers have tested coupled approaches down to very low visibility minima (perhaps even zero-zero), but it seems that even with the current capability levels of autopilot technology and ILS ground station sophistication, there's no way for a helicopter to land in minima below RVR 1200'/DA 100' (i.e. the &quot;half minima&quot; rule applied to a standard ILS, or a COPTER ILS procedure).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="595" LastEditDate="2015-08-15T09:36:34.103" LastActivityDate="2019-07-12T21:16:05.267" Title="Why haven't helicopter CAT III procedures ever been developed?" Tags="&lt;helicopter&gt;&lt;autopilot&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18876" PostTypeId="2" ParentId="18874" CreationDate="2015-08-13T23:19:53.203" Score="5" Body="&lt;p&gt;See the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f2a0fd023686c2a56e8afa1863540324&amp;amp;mc=true&amp;amp;node=se14.3.125_1211&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA FAR Here&lt;/a&gt; for the full regulations but it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Except as provided in paragraphs (b)(1) and (b)(2) of this section, each person on board an airplane operated under this part shall occupy an approved seat or berth with a separate safety belt properly secured about him or her during movement on the surface, takeoff, and landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;the regulations go on to talk about different things that make an approved seat but it does not really talk about jump seats in particular. There does not seem to be anything particularly forbidding it unless they are not considered an approved seat or berth (I'm still trying to find more on that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what it's worth, there could be an issue in allowing a passenger to use the jump seat (essentially buy that seat for the price or reduced price of a ticket) since it was not available to the other patrons at the time of ticket purchase.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="14897" LastEditDate="2017-08-05T04:03:28.617" LastActivityDate="2017-08-05T04:03:28.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18877" PostTypeId="2" ParentId="11246" CreationDate="2015-08-14T01:26:10.837" Score="2" Body="&lt;p&gt;At the York Soaring Association (northwest of Toronto) we mainly use a Schweizer 2-32 for spin training, which is mandatory for all pre-solo student pilots, as well as advanced spin training for our pilots in the aerobatic training program.  The 2-32 was also known as the X-26 Frigate in NASA's astronaut training program and was used as a platform for what they called 'yaw/roll coupling' training. I.E. it spins like crazy!  As an aerobatic instructor I've spun the 2-32 many times and the Beggs-Mueller recovery works well in this a/c.  However, we stress that pilots review and be familiar with the spin recovery technic of the particular aircraft they will be flying and use the recommended spin recovery method in the POH for that aircraft.  Also, that they NEVER intentionally put an a/c into a spin that is not certified for spins!  Many glider POH's are pretty sketchy about spin recovery and in that case I would recommend the standard Transport Canada ( or FAA) spin recovery technic.  Finally, be especially anal about the weight and balance calculations of your aircraft before doing spins. One other thing; we take high tows for spin training (about 1 mile above ground) because multiple spins can chew up a lot of altitude very fast. Our hard deck for recovery is 2,000 ft. agl, which is not only air law in Canada but just plain common sense.  Done properly and safely spins are uber fun and great training exercises.   &lt;/p&gt;&#xA;" OwnerUserId="9794" LastActivityDate="2015-08-14T01:26:10.837" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18878" PostTypeId="2" ParentId="18874" CreationDate="2015-08-14T02:02:03.243" Score="7" Body="&lt;p&gt;If you're talking about one of the jumpseats in the flight deck (as opposed to the ones FAs use in the passenger cabin,) then, &lt;strong&gt;no, it's definitely not allowed during flight, at least not in the U.S. or E.U.&lt;/strong&gt; It may be allowed elsewhere, though.&lt;/p&gt;&#xA;&lt;h3&gt;The United States&lt;/h3&gt;&#xA;&lt;p&gt;Relevant regulations for the U.S.: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:3.0.1.1.7&amp;amp;rgn=div5#se14.3.121_1547&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.547&lt;/a&gt; for domestic air carriers and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:3.0.1.1.9&amp;amp;rgn=div5#se14.3.129_128&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 129.28&lt;/a&gt; for foreign ones.&lt;/p&gt;&#xA;&lt;p&gt;The regs are a bit too long to quote here, but, to summarize: You're not getting into the flight deck during flight unless you have a valid, FAA-approved reason to be there. The mentioned exceptions were mostly FAA, NTSB, airline, or manufacturer employees and, even then, only ones with legitimate safety or operational reasons to be there. It is also mentioned that the PIC retains the emergency authority to deny access to even the FAA/NTSB/etc. personnel in the interest of safety.&lt;/p&gt;&#xA;&lt;p&gt;Apart from all of the aforementioned categories of people allowed &amp;quot;a crewmember&amp;quot; is listed separately as being allowed, of course.&lt;/p&gt;&#xA;&lt;p&gt;Also, there's &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=sp14.3.121.t&amp;amp;rgn=div6#se14.3.121_1557&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.557(a)&lt;/a&gt; which says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In an emergency situation that requires immediate decision and action the pilot in command may take any action that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter, to the extent required in the interests of safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This exception allows the pilot of a Part 121 operation to deviate from any Federal Aviation Regulation when it is required in the interest of safety. So, the Pilot-in-Command may allow you to sit in the flight deck if he deems it's necessary for safe operation of the aircraft. As such, this exception allows other pilots to access the flight deck in the very rare instances where one of the pilots falls ill and the pilot-in-command decides to get another (non-airline) pilot who happens to be on board to sit in the right seat to help out for the remainder of the flight.&lt;/p&gt;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/a/18893/755&quot;&gt;Pondlife's excellent answer here&lt;/a&gt; for more information regarding emergency authority of the pilot-in-command.&lt;/p&gt;&#xA;&lt;h3&gt;The European Union (EASA)&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://travel.stackexchange.com/a/22758/12011&quot;&gt;This answer over at travel.SE&lt;/a&gt; also mentions that &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ%3aL:2012:296:0001:0148%3aEN%3aPDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAT.GEN.MPA.135&lt;/a&gt; is the relevant EASA (E.U.) regulation preventing passenger access to the flight deck during flight.&lt;/p&gt;&#xA;&lt;h3&gt;Exceptions&lt;/h3&gt;&#xA;&lt;p&gt;As a notable exception, &lt;a href=&quot;https://aviation.stackexchange.com/a/12870/755&quot;&gt;this answer here at aviation.SE&lt;/a&gt; does mention that South Africa allows licensed pilots to visit the flight deck during flight and that you might even get to ride in the jump seat.&lt;/p&gt;&#xA;&lt;p&gt;Conclusion: I need to visit South Africa. :)&lt;/p&gt;&#xA;&lt;h3&gt;Other Related SE Questions&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/12863/755&quot;&gt;Can a passenger request to visit the cockpit during a flight?&lt;/a&gt; (Aviation)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/9253/755&quot;&gt;Can I get a photo with the pilots?&lt;/a&gt; (Aviation)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://travel.stackexchange.com/q/22744/12011&quot;&gt;Can a child still visit the cockpit during flight?&lt;/a&gt; (Travel)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://travel.stackexchange.com/q/20959/12011&quot;&gt;Can passengers visit the flight attendants' sleeping quarters?&lt;/a&gt; (Travel)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-14T19:51:25.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18879" PostTypeId="2" ParentId="18869" CreationDate="2015-08-14T02:07:17.260" Score="-1" Body="&lt;p&gt;Yes.  However, the CFI must log the training as accomplishing the instrument time for the commercial certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2010/theriault%20-%20(2010)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow&quot;&gt;Theriault interpretation.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-08-14T02:07:17.260" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18880" PostTypeId="2" ParentId="18858" CreationDate="2015-08-14T02:12:24.450" Score="0" Body="&lt;p&gt;I agree with Eric.  Many business jets gave a spoiler on feature which aids the pilot with roll control.  Spoilerons are typically activated with a flaps below a preset level and aileron movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilerons usually rise up when the aileron on the side rises.  Thus, they aid in rolling the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most likely on takeoff the pilots are correcting for winds and the spoileron system is active.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-08-14T02:12:24.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18881" PostTypeId="2" ParentId="18858" CreationDate="2015-08-14T02:25:27.330" Score="3" Body="&lt;p&gt;In this case, the flight spoilers are being used for roll control. Usually, the spoilers are used for roll control in concert with the ailerons, and are used during descent in order to slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However spoilers are also used during take off in case of a cross wind.In that case, the pilot may want to reduce some lift in the &lt;em&gt;upwind&lt;/em&gt; wing and employ spoilers instead of/along with the ailerons. A very small deflection in spoilers helps in increasing the drag over the wing and thus aid in roll control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is to be noted that the operation of spoilers during takeoff is very restricted in order to prevent flow separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern aircraft, the spoilers are used automatically with the ailerons. So, when the pilot operates the yoke, he is not consciously deciding to employ them, but rather the control system does it for him.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-14T02:25:27.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18882" PostTypeId="1" AcceptedAnswerId="18893" CreationDate="2015-08-14T03:26:54.460" Score="8" ViewCount="2207" Body="&lt;p&gt;When writing an answer to &lt;a href=&quot;https://aviation.stackexchange.com/q/18874/755&quot;&gt;this question&lt;/a&gt; regarding flight deck access during flight, I mentioned the authority of the PIC to deviate from regs as necessary for safety purposes, citing the usual FAR, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.2&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.3(b)&lt;/a&gt;, which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, the exact wording used here made me wonder exactly how far this reg has been interpreted to go. In particular, it grants the PIC emergency ability to deviate from &lt;code&gt;&quot;Any rule of this part&quot;&lt;/code&gt;, which would be 14 CFR Part 91. So, does this authority extend only to Part 91 of the FARs or does it extend to all of the FARs? The exact wording seems to suggest it only applies to Part 91 and not, say, Part 121, which was the part under consideration in the other question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the major things I'm wondering are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;What is the extent of the authority granted by 14 CFR 91.3(b)?&lt;/strong&gt; and&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;If 14 CFR 91.3(b) indeed only applies to Part 91, is there a similar explicit emergency PIC authority exception to the other Parts of the FARs?&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Obviously, the PIC is the one in charge and will deviate where necessary for safety regardless of regs and worry about the explaining later after he's ensured he'll be alive to explain, but I'm curious about the regulatory basis for deviation from FARs.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-11-15T13:55:46.807" Title="What is the Extent of the Emergency Authority of the Pilot-in-Command (FAA)?" Tags="&lt;faa-regulations&gt;&lt;emergency&gt;&lt;pilot-authority&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18883" PostTypeId="2" ParentId="18858" CreationDate="2015-08-14T05:14:51.967" Score="7" Body="&lt;p&gt;Spoilers lower lift and increase drag on the side where they are deployed. Symmetric spoiler deployment, therefore, is for slowing down. Asymmetric deployment not only creates a (small) rolling moment, but primarily a yawing moment which helps to counteract the &lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw&quot;&gt;adverse yaw&lt;/a&gt; created by ailerons, especially at the high lift coefficient at takeoff and early climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoiler deployment increases pressure ahead of the spoiler due to the slowing of local flow ahead of the obstruction caused by the spoiler, and it creates a local flow separation at and behind the spoiler, which in turn lowers the local pressure. Only the first effect lowers lift, but both create drag. The main effect of a limited spoiler deflection, therefore, is to increase drag.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-08-14T05:14:51.967" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18884" PostTypeId="1" AcceptedAnswerId="18886" CreationDate="2015-08-14T05:20:29.623" Score="13" ViewCount="7424" Body="&lt;p&gt;I read somewhere that the Ilyushin Il-62 had a &quot;tail prop&quot;.  What was this device and why was it needed on this aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="22726" LastEditDate="2019-01-10T03:58:48.857" LastActivityDate="2020-07-28T16:45:16.343" Title="What was the purpose of the &quot;tail prop&quot; on the Ilyushin Il-62 and why was it necessary?" Tags="&lt;aircraft-design&gt;&lt;il-62&gt;" AnswerCount="9" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18885" PostTypeId="2" ParentId="18884" CreationDate="2015-08-14T05:35:58.483" Score="18" Body="&lt;p&gt;The 'tail prop' is more accurately described as a tail support. I remember seeing these on Il-62s at Heathrow in the 70s. They were deployed as the aircraft arrived at the gate, and retracted just before pushback.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally, the aircraft had a propensity to tilt backwards and strike the tail on the ground during loading and unloading operations as the CG moved. The tail support eliminated this possibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XZEYN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XZEYN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user8807" LastActivityDate="2015-08-14T05:35:58.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18886" PostTypeId="2" ParentId="18884" CreationDate="2015-08-14T05:40:32.407" Score="19" Body="&lt;p&gt;Are you asking about the rear support wheel? It is for supporting the aircraft and avoiding tilt on the ground.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/gsiYG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gsiYG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Image from wikimedia commons. Autor:M Radzi Desa&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft had four engines in the aft, the cg would've been aft too; so they added a tail prop to prevent tilt on ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, this doesn't seen to be unique for Il-62. Another aircraft with rear mounted engine, Sud Aviation Caravelle, has something similar to this. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/KyOhT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KyOhT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Image from wikimedia commons. Author: Eduard Marmet&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-14T12:05:55.900" LastActivityDate="2015-08-14T12:05:55.900" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18887" PostTypeId="1" AcceptedAnswerId="18888" CreationDate="2015-08-14T06:39:19.483" Score="1" ViewCount="417" Body="&lt;p&gt;The people from &lt;a href=&quot;http://www.cruiser-feeder.eu/&quot; rel=&quot;nofollow noreferrer&quot;&gt;cruiser-feeder&lt;/a&gt; started a project called RECREATE. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, for the concept with fuel transfer from feeder to cruiser (civil air-to-air refuelling operations), the results of our collaborative research indicate a fuel burn reduction potential on isolated aircraft level between 11% and 23 % for a typical 6000 nautical miles flight with a payload of 250 passengers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That sounds very good, doesn't it? I answered &lt;a href=&quot;https://aviation.stackexchange.com/questions/17504/why-dont-airliners-use-in-air-refueling-systems/17526#17526&quot;&gt;this&lt;/a&gt; question about civil air-to-air refuelling with the cruiser feeder concept. A User said:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;with the Breguet equation it is easy to see that the savings are modest.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This concept will never be certified&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They even created a high-realistic simulation environment in which they tested the refuelling-process with real pilots as you can see &lt;a href=&quot;https://www.youtube.com/watch?list=PL78F02CFCF1D2C6C5&amp;amp;v=cLzfIncPNxs&quot; rel=&quot;nofollow noreferrer&quot;&gt;in this video&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The feedback from the pilot is very good and promising that the concept might become real.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious why the savings are modest, because the planes can reduce the fuel burn from 11% to 23% and why this concept will never be certified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the cruiser-feeder concept become real? That a feeder pumps fuel to a cruiser after he took of?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When does the use of the feeder burn more fuel than it saves?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What could stand in the way to make the RECREATE Project become real?&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-08-14T10:30:26.823" Title="Cruiser-Feeder Concept - feasible?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;refueling&gt;&lt;mid-air-refueling&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-08-14T14:12:13.747" ContentLicense="CC BY-SA 3.0" />
  <row Id="18888" PostTypeId="2" ParentId="18887" CreationDate="2015-08-14T07:49:42.290" Score="4" Body="&lt;p&gt;The system is highly impracticable for a number of reasons.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The referred paper acknowledges that the fuel savings due to existing tankers are negligible and a new design is required. I doubt anyone is going to develop this. Even the military uses modified civil airliners for its tankers needs. Development of the tanker as outlined in the paper will cost billions of dollars and no one is going to do that for a handful of tankers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even if such a tanker is built, the existing aircraft will require significant modifications for in flight refueling (assuming that the tanker is standardized from day one, which is practically not possible; even the US armed forces use two different type of tankers). Basically, the structural weight goes up,which reduces performance and increases fuel consumption.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Then the pilots have to be trained for operations of both the aircraft. In flight refuelling is potentially dangerous.See &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/aerial-refueling-hooking-up-is-hard-to-do-1559495801&quot; rel=&quot;nofollow&quot;&gt;http://foxtrotalpha.jalopnik.com/aerial-refueling-hooking-up-is-hard-to-do-1559495801&lt;/a&gt;. Nobody's going to take that risk with civil operations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The study is extremely simplistic. modern civil aircraft fly in a number of 'flight levels', separated by set altitude. So, for refueling, either the tanker or receiver should climb or descend the difference in altitude, and that burns up more fuel.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If carrying extra fuel in the aircraft is dead weight, it makes no sense to carry it in another aircraft and pay for its operations and maintenance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is not correct to compare the military and civil operations. Their priorities, methods and end goals are different. What looks good on paper may not work on real life. Remember Concorde?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1467" LastEditDate="2015-08-14T07:51:35.360" LastActivityDate="2015-08-14T07:51:35.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18889" PostTypeId="2" ParentId="18887" CreationDate="2015-08-14T10:30:26.823" Score="0" Body="&lt;p&gt;The savings for the cruiser/feeder concept come from two main areas:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Cruiser fuel saving as it does not have to carry the fuel for the second leg of the journey during the first leg (first leg is before refuelling, second leg is after). The feeder is much smaller and flies a shorter distance than the cruiser, this is what makes the process efficient.&lt;/li&gt;&#xA;&lt;li&gt;Smaller cruiser as you do not need as large an aircraft to fly the same distance. E.g. rather than a 6000nm cruiser you can design an aircraft for a design range of 3000nm. It there has a much smaller operating empty weigh etc. and is therefore more fuel efficient.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So the answers talking about using simple calculations such as the Breguet equation are misguided, as they have completely ignored one of the main areas of fuel saving, the fact that you use a smaller and more fuel efficient aircraft to fly the same distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main issue is that you can largely get the same effect with staging the journey. Rather than having a feeder aircraft, you simply land and refuel. This obviously eliminates the feeder, but has its own problems (longer journey times, more take off/landings at busy airports).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are clear fuel savings to be made with the cruiser/feeder concept for a specific subset of journeys. It just seems a large investment when the same effect can be implemented with staging much more easily.&lt;/p&gt;&#xA;" OwnerUserId="9796" LastActivityDate="2015-08-14T10:30:26.823" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="18890" PostTypeId="1" AcceptedAnswerId="18892" CreationDate="2015-08-14T11:02:45.203" Score="8" ViewCount="4762" Body="&lt;p&gt;I've recently picked up flying lessons for ULL (similar to LSA in N.America). I've thought I've been doing pretty well (I guess my experience with computer simulation helped considerably).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet more and more I seem to have trouble with my feet and controlling the rudder - my instructor(s) tell me that I just seem to be &quot;unwilling&quot; to move them, yet it just seems to me somehow unnatural and awkward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there some tips for novice pilots on how to dive into the rudder-control, best feet stance etc? (I tried to do a web search but couldn't find anything useful.) Or is it a normal thing for beginners to struggle with this?&lt;/p&gt;&#xA;" OwnerUserId="6805" LastEditorUserId="19" LastEditDate="2016-07-08T09:54:06.593" LastActivityDate="2016-07-10T23:06:37.257" Title="What advice would you give a novice pilot on controlling the rudder?" Tags="&lt;student-pilot&gt;&lt;rudder&gt;" AnswerCount="5" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18891" PostTypeId="2" ParentId="18890" CreationDate="2015-08-14T11:24:16.747" Score="1" Body="&lt;p&gt;I guess its normal for beginners and more practice will help. It did for me anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I learnt, my instructor told me when I was turning to think Bank Angle-Back Pressure-Ball, and repeat this while the aircraft was turning so I could monitor the ball (glancing in and checking once every ten seconds, looking out the rest of the time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are climbing or descending you will need rudder one way or the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other main use is when you are turning, e.g. if you move the ailerons, you should move the rudder at the same time, but when you are at the correct bank angle, you come off the ailerons and also come off the rudder as a rule, just making very minor adjustments as part of the Bank Angle-Back Pressure-Ball routine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to start with, try to practice moving the rudder every time you move the ailerons, even if only making a minor correction to heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, just as I was told I shouldn't be flying more than 30 degrees angle of bank at low level in the circuit, neither should you be using the rudder on its own, or cross controlling (right aileron, left rudder for example). Giving the rudder a big kick on its own at low speed is the recommended way to get into a spin, not something you want to do at low level. So while you shouldn't be scared of it, do respect the rudder and try to fly in balance at all times, particularly when at low level / low speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to add I'm not a flying instructor, I'm only trying to give you some helpful hints here. Hope this helps.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-14T11:24:16.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18892" PostTypeId="2" ParentId="18890" CreationDate="2015-08-14T11:24:23.587" Score="5" Body="&lt;p&gt;It's very normal for most students to struggle with the rudder initially. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;One aspect that got me while learning to fly:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike stick inputs is not 'applied pressure' that measures the effect of the rudder, but the actual physical displacement of the pedal. It was quite usual for me to feel the need for right rudder, increase pressure on the pedal but with very little actual pedal movement, so there was practically no effect on the a/c. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I made a conscious effort when right rudder was needed to apply pressure enough &lt;em&gt;To Move The Pedal&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words if you want to double the effect of the rudder you need to double the pedal displacement, not double the pressure applied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second thing that got me to using the rudder correctly:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make a mental note to use rudder &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;when using the ailerons &lt;/li&gt;&#xA;&lt;li&gt;when changing power settings. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Pretty soon these actions will become linked by the brain and you will do it unconsciously. Then with time you will also learn to use the correct amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;On feet stance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am pretty short at 1.70m so I was usually selecting the closest setting for rudder which was placing the rudders very close to my knees, and as such it was difficult to properly use them (as my body was literally resting on the pedals). I was once advised to push them further back and it has made a world of difference: adjust them so that maximum deflection requires just a little bit of hip effort and almost a straight knee. Try a couple of positions and see which one works best; your instructor can help to show you the proper adjustment, and it does make a word of difference.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2015-08-14T11:29:26.800" LastActivityDate="2015-08-14T11:29:26.800" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18893" PostTypeId="2" ParentId="18882" CreationDate="2015-08-14T12:30:39.273" Score="14" Body="&lt;p&gt;The scope of the part 91 exception is exactly what it says: deviate from any rule &lt;em&gt;of this part&lt;/em&gt;, i.e. part 91. But remember that part 91 applies to all flights anyway; part 121 (or 135 etc.) regulations are in addition to part 91, not instead of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that still means that 91.3(b) doesn't give any authority to deviate from other parts, like 135 or 121 regulations. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a6f1d4394ea7d5d364841a5769c72e30&amp;amp;mc=true&amp;amp;node=se14.3.135_119&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 135.19(b)&lt;/a&gt; is the equivalent authority for part 135 operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In an emergency involving the safety of persons or property, the pilot&#xA;  in command may deviate from the rules of this part to the extent&#xA;  required to meet that emergency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the language is again &lt;em&gt;of this part&lt;/em&gt;. So in an emergency, the PIC of a part 135 flight can deviate from part 91 rules per 91.3 and from part 135 rules per 135.19.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 121 is a little different. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ba1049ed6b58219762376b52e056d847&amp;amp;mc=true&amp;amp;node=sp14.3.121.t&amp;amp;rgn=div6#se14.3.121_1557&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.557(a)&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In an emergency situation that requires immediate decision and action&#xA;  the pilot in command may take any action that he considers necessary&#xA;  under the circumstances. In such a case he may deviate from prescribed&#xA;  operations procedures and methods, weather minimums, and this chapter,&#xA;  to the extent required in the interests of safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here, the regulation allows for deviations from any part of &lt;em&gt;this chapter&lt;/em&gt;, not &lt;em&gt;this part&lt;/em&gt; as in the part 91 and 135 regulations. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?gp=&amp;amp;SID=ba1049ed6b58219762376b52e056d847&amp;amp;mc=true&amp;amp;tpl=/ecfrbrowse/Title14/14chapterI.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chapter I of title 14&lt;/a&gt; is at a higher level: it includes all parts of the FAA's aviation regulations, so under part 121 emergency authority the PIC can deviate from &lt;em&gt;any&lt;/em&gt; aviation regulation, not just the ones in part 91 or 135.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="1467" LastEditDate="2019-11-15T13:55:46.807" LastActivityDate="2019-11-15T13:55:46.807" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="18894" PostTypeId="2" ParentId="18856" CreationDate="2015-08-14T12:36:43.863" Score="1" Body="&lt;p&gt;I don't know much about the ASRS, so but I think this is a similar program... It's obviously not Europe, but Australia has the &lt;a href=&quot;https://www.atsb.gov.au/voluntary/repcon-aviation.aspx&quot; rel=&quot;nofollow&quot;&gt;REPCON&lt;/a&gt; scheme for confidentially reporting all sorts of safety matters. The ATSB do a bit of investigating, seeking a response from the airline/whatever organisation is involved, and then publish the responses to a couple in CASA's Flight Safety Australia magazine. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-08-14T12:36:43.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18895" PostTypeId="2" ParentId="11818" CreationDate="2015-08-14T12:41:48.637" Score="13" Body="&lt;p&gt;There are some good answers here. I would just like to add a few points:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I don't like this idea of feeling for ground effect. I think this is unreliable, and will be different in different aircraft and conditions. I can only imagine the aircraft in a steeper than usual descent when I think of this, and not detecting ground effect because you have flown through it and hit the ground - hard.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Try to memorise the picture on the ground before take off, when sat in the cockpit. This will help.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Be aware of your peripheral vision, particularly around the sides of the dash (if you can see the runway that is). So while you should be looking in the middle distance, when the sides of the runway reach the same level as you, you are there.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You should always have some sink rate, so flaring too much and flying level or climbing, is clearly not right. So for example, rather than just pulling back on the stick to flare, reduce power at the same time as flaring just a little. That should increase your sink unless you are still a bit fast (Actually, if it does not thats an indicator that you are a bit fast).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Finally, you see lots of pilots kind of &quot;feeling for the ground&quot; by pulling back and then easing off then pulling back some more. Eventually the aircraft runs out of airspeed and falls the last 5 feet or so and the landing isn't too bad. A better technique would be to fly to the runway, fly level a little while, and just trying to keep the aircraft level by gradually applying back pressure. The gradual reduction in speed does the rest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also relax! And practice! That's the hard bit given the cost of flying!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. I'm not a flight instructor, my only claim to fame is successfully landing a full motion 737 sim once with no instruction apart from air traffic responding to my Mayday call and telling me to fly the initial approach at 170 and threshold 130 (and giving me vectors to the ILS). Hope this helps you though.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-14T12:41:48.637" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="18897" PostTypeId="1" AcceptedAnswerId="18899" CreationDate="2015-08-14T14:02:50.643" Score="18" ViewCount="7154" Body="&lt;p&gt;I hear and read both the terms &quot;aerobatic&quot; and &quot;acrobatic&quot; used to describe the more extreme maneuvers such as spins, rolls, loops and more. My questions is about the terms themselves. It seems that they are interchangeable, but is one actually more correct to use than the other? Why do we have these two very similar words in the aviation vernacular that seem to mean the same thing?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="3386" LastEditDate="2015-09-19T13:13:56.293" LastActivityDate="2017-10-31T18:17:22.133" Title="Is there a difference between &quot;aerobatic&quot; and &quot;acrobatic&quot; flight?" Tags="&lt;terminology&gt;&lt;aerobatics&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18898" PostTypeId="2" ParentId="18897" CreationDate="2015-08-14T14:11:59.277" Score="1" Body="&lt;p&gt;In my opinion, acrobatic is more related to a person, &quot;One who is skilled in feats of balance and agility in gymnastics&quot;.&#xA;However, aerobatic relates to maneuvers on the air.&lt;/p&gt;&#xA;" OwnerUserId="9458" LastActivityDate="2015-08-14T14:11:59.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18899" PostTypeId="2" ParentId="18897" CreationDate="2015-08-14T14:14:16.323" Score="22" Body="&lt;p&gt;Acrobatic is being incorrectly used, although it is slightly more complicated than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Aerobatic&quot; refers specifically to flight, and &quot;acrobatic&quot; refers specifically to feats of the human body, so referring to an aircraft as performing acrobatics is wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerobatics&quot;&gt;the word &quot;aerobatic&quot; is derived from &quot;aero-acrobatics&quot;&lt;/a&gt; and sounds nearly identical, so it's an understandable and relatively common error.&lt;/p&gt;&#xA;" OwnerUserId="9800" LastEditorUserId="64" LastEditDate="2015-08-14T17:06:05.923" LastActivityDate="2015-08-14T17:06:05.923" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18900" PostTypeId="2" ParentId="15188" CreationDate="2015-08-14T14:28:15.990" Score="4" Body="&lt;p&gt;As a passenger I wish:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To have a good choice of flight times &lt;/li&gt;&#xA;&lt;li&gt;Not to have to wait a long time while other aircraft are unloading&lt;/li&gt;&#xA;&lt;li&gt;Not to have long queues&lt;/li&gt;&#xA;&lt;li&gt;Not to have my flight be delayed due to issues with another flight&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The above does not sit well with 'You need to schedule a number of aircraft all flying the same route at the same time for a significant amount of time'.&lt;/p&gt;&#xA;" OwnerUserId="1792" LastEditorUserId="337" LastEditDate="2015-08-14T17:24:14.490" LastActivityDate="2015-08-14T17:24:14.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18901" PostTypeId="2" ParentId="5019" CreationDate="2015-08-14T17:53:21.217" Score="1" Body="&lt;p&gt;It cannot fly between any two airports for a simple reason. Any departure from an airport that is located above 2,000m (e.g. Addis Ababa) would reduce the range due to lower fuel capacity in the tanks.&lt;/p&gt;&#xA;" OwnerUserId="9807" LastActivityDate="2015-08-14T17:53:21.217" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18902" PostTypeId="2" ParentId="18897" CreationDate="2015-08-14T18:07:57.023" Score="7" Body="&lt;p&gt;The Oxford English Dictionary's etymology for &quot;aerobatics&quot; is &quot;After &lt;em&gt;acrobatics&lt;/em&gt;&quot; and defines it as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Feats of expert aviation, performed esp. for display. Hence &lt;strong&gt;aeroˈbatic&lt;/strong&gt; &lt;em&gt;a&lt;/em&gt;.; &lt;strong&gt;ˈaerobat&lt;/strong&gt;, one who performs aerobatics; hence as &lt;em&gt;v. intr&lt;/em&gt;., to perform aerobatics; also &lt;em&gt;trans&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's a new word pertaining to aviation based on one for (also Oxford English Dictionary):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A rope-dancer; a performer of daring gymnastic feats and evolutions; a tumbler. &lt;em&gt;lit&lt;/em&gt;. and &lt;em&gt;fig&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Edit: Notice the &lt;em&gt;fig.&lt;/em&gt; at the end of the definition (which is an abbreviation for &lt;em&gt;figuratively&lt;/em&gt;).  So &quot;acrobatic&quot; can correctly be used to describe a person, cat, &lt;strong&gt;airplane&lt;/strong&gt;, &lt;em&gt;etc&lt;/em&gt;... performing &quot;acrobatics&quot;.&lt;/p&gt;&#xA;" OwnerUserId="9806" LastEditorUserId="9806" LastEditDate="2015-08-15T17:57:46.640" LastActivityDate="2015-08-15T17:57:46.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18903" PostTypeId="1" AcceptedAnswerId="18906" CreationDate="2015-08-14T18:24:31.520" Score="10" ViewCount="1929" Body="&lt;p&gt;Some airports have an area, on the threshold, used to back track the aircraft, mainly because of the their wingspan, they look like a half wheel.&#xA;Is there any designation for this area?&lt;/p&gt;&#xA;" OwnerUserId="9458" LastEditorUserId="1696" LastEditDate="2015-08-14T21:24:20.447" LastActivityDate="2017-10-20T08:10:43.483" Title="Is there a name for the area for aircraft to back track near the runway threshold?" Tags="&lt;runways&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18904" PostTypeId="2" ParentId="18884" CreationDate="2015-08-14T19:12:18.490" Score="13" Body="&lt;p&gt;They're called &quot;tail stands&quot; for planes such as the Cessna Caravan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During loading and unloading the CG can be tail-heavy enough that the aircraft would otherwise fall back on its tail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1mTNH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1mTNH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2055" LastActivityDate="2015-08-14T19:12:18.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18905" PostTypeId="2" ParentId="18903" CreationDate="2015-08-14T19:15:54.270" Score="14" Body="&lt;p&gt;It sounds like you're talking about these:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f0K8d.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f0K8d.jpg&quot; alt=&quot;Runway turnaround area&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if the designation is &quot;official&quot;, but pilots in the US (and the FAA in various documents) usually refer to such areas as a &quot;Runway Turnaround Area&quot; or simply &quot;Runway Turnaround&quot;.&lt;br&gt;&#xA;Their purpose is to allow aircraft which have back-taxied on the runway (or landed and rolled past the taxiway turn-offs) to &lt;em&gt;turn around&lt;/em&gt; to position for take-off or return to a taxiway turn-off.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that the &quot;runway turnaround&quot; is distinct from a &quot;run-up area&quot;: The runway turnaround is considered to be &lt;em&gt;part of the runway&lt;/em&gt;, so an aircraft occupying that area is occupying the runway. A run-up area is generally a distinct area, usually off a taxiway, where aircraft can perform engine run-ups prior to entering the runway.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/kAtVd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kAtVd.jpg&quot; alt=&quot;Run-Up area &amp;amp; markings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-14T19:15:54.270" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="18906" PostTypeId="2" ParentId="18903" CreationDate="2015-08-14T19:52:46.890" Score="3" Body="&lt;p&gt;I don't know if it is official, but across Europe, Middle East, Asia, and north Africa I hear using &quot;turnpad&quot;, and many ATC in these regions provide directions like &quot;bactrack via turnpad and continue taxi via taxiway A&quot;, that means go ahead to turnpad bactrack and vacate runway via taxiway A. &lt;/p&gt;&#xA;" OwnerUserId="9809" LastEditorUserId="1467" LastEditDate="2017-10-20T08:10:43.483" LastActivityDate="2017-10-20T08:10:43.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18907" PostTypeId="1" AcceptedAnswerId="18908" CreationDate="2015-08-14T20:42:06.420" Score="7" ViewCount="732" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dfacf918de4cdc45d4428fe477a12ab4&amp;amp;mc=true&amp;amp;node=se14.2.91_1183&amp;amp;rgn=div8&quot;&gt;14 CFR 91.183&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless otherwise authorized by ATC, the pilot in command of each aircraft operated under IFR must report the following as soon as possible: Any unforecast weather conditions encountered; and any other &lt;strong&gt;information relating to the safety of flight&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This language is very vague and probably causes a lot of confusion for pilots who are studying it. Does the FAA elaborate on this concept or provide an examples or a more specific definition somewhere else? If not, what are some examples of reports ATC would expect based on this reg?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-14T21:18:11.093" Title="How is &quot;information relating to the safety of flight&quot; defined by the FAA?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18908" PostTypeId="2" ParentId="18907" CreationDate="2015-08-14T21:18:11.093" Score="6" Body="&lt;p&gt;The language is &lt;strong&gt;&lt;em&gt;intentionally&lt;/em&gt;&lt;/strong&gt; vague.&lt;br&gt;&#xA;Much like Justice Stewart said about pornography, when it comes to &quot;information relating to the safety of flight&quot; &lt;a href=&quot;https://en.wikipedia.org/wiki/I_know_it_when_I_see_it&quot;&gt;you'll know it when you see it.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Birds flying around in the approach path? Yup.  &lt;/li&gt;&#xA;&lt;li&gt;Wind shear on short final? Yup.&lt;br&gt;&#xA;(Even if it's forecast/reported telling them how much airspeed you gained or lost helps.)&lt;/li&gt;&#xA;&lt;li&gt;&quot;Drone&quot; buzzing around in the traffic pattern? Yup.&lt;/li&gt;&#xA;&lt;li&gt;Deer grazing in the middle of a grass runway? Yup.&lt;/li&gt;&#xA;&lt;li&gt;Bird strike? Absolutely.&lt;br&gt;&#xA;(There are regs/procedures specifically for this.)&lt;/li&gt;&#xA;&lt;li&gt;The guy in row 3J is threatening the flight attendants? Yup.&lt;/li&gt;&#xA;&lt;li&gt;The guy in row 3J spilled his soda on his lap? …Not so much.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-14T21:18:11.093" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18909" PostTypeId="2" ParentId="18745" CreationDate="2015-08-14T21:38:19.780" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a difference in complexity as to whether it's a passenger aircraft or a freighter being loaded?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, very much so. The resulting load of a passenger in every seat is nowhere near close to the structural limits (note that I said structural limits, not performance limits). Generally speaking, having to check for the load being within structural limits is a concern for freighters, not passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a lot of structural considerations for the semi-monocoque design used for all modern large aircraft. Using one variant of a 747-400F as an example, its Weight and Balance Control and Loading Manual runs to 584 pages. Items that need to be checked for each load include:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Linear and Floor Loading&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2NAat.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2NAat.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manual snippet above covers the main deck; there are like tables for each cargo area. The linear loading is the lb/in measured along the longitudinal axis of the airplane. I don't really understand why it's necessary to check both the linear loading and the floor loading, given above as lb/sq ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not only does the linear loading for each cargo compartment need to be checked, but the combined linear loading of all decks together along the longitudinal axis has separate linear limits as tabled below: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dfy8Q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dfy8Q.jpg&quot; alt=&quot; 7&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Cumulative Loading&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are cumulative load limits for both the forward body and the aft body. Using the forward body for example, you add up individual items (more often than not &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;ULDs&lt;/a&gt;) starting at the front and proceeding to a point over the wing box. I'm not sure exactly how that point is chosen insofar as structural and aerodynamic considerations are concerned. The aft body cumulative load starts from the tail and proceeds to the same point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a forward body cumulative limits graph. Note that there are two lines: one for use when the ZFW is 610,000 lbs or below, one from that weight up to 635,000 lbs. For this particular airplane, the aft body also has two lines, but the differentiation is based on the takeoff c.g.. Some 747s have only one line for each, some one line for one but two lines for the other. Obviously things can get tediously complex, and loadmasters and the software they're using has to accommodate all the possibilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/58jlH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/58jlH.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Unsymmetrical Main Deck Limits&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Widebody aircraft that can accommodate two rows of ULDs on the main deck have the option of carrying more weight in one container if the container laterally next it is given a lower limit. I know of one operator that didn't want to contend with the limit of, say, the position on the left being higher than the position on the right, and chose to forego the flexibility of unsymmetrical limits. An unsymmetrical limit graphs is below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tx96Q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tx96Q.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, does anyone want to do a weight and balance for a large cargo aircraft? Fortunately we have software to do that for the great majority of loads that are containerized. However, loadmasters might still have to contend with unusual loads manually.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-08-14T21:38:19.780" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18911" PostTypeId="2" ParentId="18884" CreationDate="2015-08-14T22:29:33.167" Score="6" Body="&lt;p&gt;It's a tail stand -- it prevents the airplane from tipping up and back onto its tailfeathers in a most embarrassing fashion, even if you have to load it back to front or unload it front to back (image from &lt;a href=&quot;http://www.aerospaceweb.org/question/design/q0200.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerospaceweb's question on landing gear&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/evgHS.jpg&quot; alt=&quot;an ACA 747 tipped on its tail&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="8282" LastEditDate="2019-01-29T18:07:19.523" LastActivityDate="2019-01-29T18:07:19.523" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="18912" PostTypeId="1" AcceptedAnswerId="18956" CreationDate="2015-08-14T22:37:19.047" Score="12" ViewCount="14594" Body="&lt;p&gt;Aircraft certified by the FAA under 14 CFR Part 23 have many V speeds, one of them which manufacturers are required to determine and publish in the POH is maneuvering speed, or Va.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In aviation, the maneuvering speed (Va) of an aircraft is an airspeed limitation selected by the designer of the aircraft. At speeds close to, and faster than, the maneuvering speed, full deflection of any flight control surface should not be attempted because of the risk of damage to the aircraft structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This speed varies with the weight of the aircraft. Why does this speed vary with weight? Additionally since manufacturers often only provide that value at max gross weight, how does one figure out what that Va airspeed is when not at max gross weight?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2019-08-06T10:40:36.890" Title="Why does maneuvering speed vary with weight?" Tags="&lt;aircraft-limitations&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18913" PostTypeId="2" ParentId="18884" CreationDate="2015-08-14T23:34:18.507" Score="2" Body="&lt;p&gt;Improvised tail-props were a feature of early, tricycle landing gear, military aircraft. Grumman's F7F Tigercat, certainly. There are photos with 55 gallon drums + assorted odds and ends as props, in place, and also photos of unsupported planes sitting with nose-wheels off the ground...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At that point in Grumman's history, nobody would have expected resting the tail on the ground would do any damage to the airplane...&lt;/p&gt;&#xA;" OwnerUserId="1897" LastActivityDate="2015-08-14T23:34:18.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18914" PostTypeId="1" CreationDate="2015-08-15T00:44:26.877" Score="3" ViewCount="623" Body="&lt;p&gt;Are &quot;remote controlled&quot; aircraft and &quot;drones&quot; the same thing? Are they synonyms for &quot;unmanned aerial vehicle&quot;?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-15T01:51:00.760" Title="What is the difference between &quot;R/C&quot;, &quot;Drone&quot;, &quot;UAV&quot;?" Tags="&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18915" PostTypeId="2" ParentId="18897" CreationDate="2015-08-15T01:29:00.303" Score="6" Body="&lt;p&gt;Some of the other answers seem to claim that acrobatics would be incorrect when used to describe aerobatics, however when you look up various definitions you will find out that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;acrobatics : difficult and dangerous acts done by an acrobat; &lt;strong&gt;also : difficult or dangerous acts, movements, etc., done by another kind of performer&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.merriam-webster.com/dictionary/acrobatics&quot; rel=&quot;nofollow&quot;&gt;http://www.merriam-webster.com/dictionary/acrobatics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, acrobatics is just the generic word, whilst aerobatics is the more specific word describing a very specific form of acrobatics: acrobatics in the air flowing from the following etymology:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;aer- + acrobatics =&gt; aerobatics&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.merriam-webster.com/dictionary/aerobatics&quot; rel=&quot;nofollow&quot;&gt;http://www.merriam-webster.com/dictionary/aerobatics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in conclusion it's fine to use either term, especially when it's already clear that the context is about aviation. In an undefined context it might however be useful to have two words, for example&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I went to an aerobatics display&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I went to an acrobatics display&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;of course hold two very different meanings. Point is just: If you can pick, pick aerobatics, but don't go correcting people who aren't saying anything wrong.&lt;/p&gt;&#xA;" OwnerUserId="1368" LastEditorUserId="1368" LastEditDate="2015-08-15T14:57:28.097" LastActivityDate="2015-08-15T14:57:28.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18916" PostTypeId="2" ParentId="18914" CreationDate="2015-08-15T01:51:00.760" Score="3" Body="&lt;p&gt;Drones are simply the common name for Unmanned Aerial Vehicles. Representatives from the industry and the military use the term UAV for the aircraft and UAS (Unmanned Aerial System) for the whole system- including communication system, on ground controller etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, technical publications call them UAVs or usually UAS's and rarely (if ever) drones. On the other hand, the mainstream media refers to them usually as drones as it is easy to communicate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ICAO (International Civil Aviation Organization) calls them remotely piloted aircraft. However, there is a subtle difference in using this word as it means that it is being flown by a pilot (controller) on ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though this may be technically true, most of the UAVs, at least those used in the military are capable of highly automated mission profiles (in fact, they depend on the controller only for weapons release) and are on the way to full autonomy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The choice of wording is one of semantics i.e. about the meaning which is to be conveyed. For example, the nobody wants a system that goes and kills someone without human intervention. So, the USAF calls the MQ-9 Reaper a Remotely Piloted Vehicle in its official page and a UAV in press releases, but not a drone, as it has negative connotations in public mind. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-15T01:51:00.760" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18917" PostTypeId="2" ParentId="18912" CreationDate="2015-08-15T02:52:32.430" Score="7" Body="&lt;p&gt;At the normal stall speeds given by $V_s$, the load on the aircraft is 1g, and the lift is equal to weight. i.e $L = W$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of maneuvering, the load factor is greater than one, and we have $L = nW$, with $n$ being the load factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have,  $L = nW = \frac{1}{2}  C_L  \rho  V^2 S$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This gives maneuvering speed , $V_a$ = $V_s \sqrt{n}$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can also be written as $V_s$ = $\sqrt{\frac{2 n W}{\rho C_{Lmax} S}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At maximum weight, this gives, &#xA;$V_A$ = $\sqrt{\frac{2 n W_{max}}{\rho C_Lmax S}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For other weights, we have,&#xA;$V_a$ = $\sqrt{\frac{2 n W_{a}}{\rho C_Lmax S}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same load factor, we then have,&#xA;$V_{a} = V_{A} \sqrt{\frac{W_{a}}{W_{max}}}$,&#xA;where&#xA;$V_{a}$ is the maneuvering speed at weight $W_{a}$ and $V_{A}$ is the maneuvering speed at maximum weight $W_{max}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the maneuvering speed depends on the load factor and the stall speed, it depends on the weight of the aircraft (which decides the stall speed). It is basically a structural limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing to note is that the aircraft &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/395c3f064247018a862577b200495b5a!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;can sustain structural failure&lt;/a&gt; even below maneuvering speed when multiple large control inputs are given. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-08-15T15:58:53.527" LastActivityDate="2015-08-15T15:58:53.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18918" PostTypeId="1" AcceptedAnswerId="18920" CreationDate="2015-08-15T10:12:51.717" Score="5" ViewCount="10101" Body="&lt;p&gt;Runways are &lt;a href=&quot;https://aviation.stackexchange.com/questions/65/how-are-runways-numbered&quot;&gt;numbered&lt;/a&gt; based on compass heading. Why?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this help pilots in locating the runway, even in today's GPS age? Or are there some other technical reasons behind this?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-01T22:10:13.613" Title="Why are magnetic headings used for designating runways?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18919" PostTypeId="2" ParentId="18918" CreationDate="2015-08-15T10:49:26.047" Score="8" Body="&lt;p&gt;The aircraft heading is measured with reference to the magnetic north. &#xA;If the same convention is used for runways too, it will make it easy for the pilot to identify the runway and land as the aircraft's heading and the runway will be aligned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if the aircraft is directed to land in the runway 09, the aircraft heading will be 090° while landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use of another system for naming will lead to unnecessary confusion. This convention is being used from long before GPS was available. Also,as already noted, a large number of aircraft flying today have no GPS and pilot should be able to land the aircraft even without it.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="524" LastEditDate="2015-08-15T14:11:02.653" LastActivityDate="2015-08-15T14:11:02.653" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18920" PostTypeId="2" ParentId="18918" CreationDate="2015-08-15T14:03:41.827" Score="11" Body="&lt;p&gt;There are two parts to the question:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Why number runways based on their direction?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The runways have to be identified somehow and the identification has to be directional. So the, rounded, heading offers itself and it has advantage that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pilot can verify they are approaching the intended runway by looking at the compass, which&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;works at night, in bad visibility or early on the approach when the numbers on the ground are not visible yet and&lt;/li&gt;&#xA;&lt;li&gt;serves as cross-check for verifying the instruments are set correctly during instrument approaches.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Since the pilot needs to know the runway heading for navigation and for checking the wind anyway, it makes it easier to remember.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Why use magnetic heading instead of true?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In the early days of aviation, magnetic compass was the only tool available for determining direction. It is simple and reliable and well tested in naval navigation. So magnetic headings became the obvious standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later gyrocompass was introduced to overcome the limitation of magnetic compass that it is biased in turns and requires some time to stabilize. However gyrocompass precesses, so it has to be periodically corrected, which was, and is, still done by reference to the magnetic compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand GPS is still a rather recent technology. It is only precise enough to determine heading (or rather tracking) for last 15 years. It requires a complex electronic device that can fail in a myriad of ways and it is affected by many external factors including the state of ionosphere and the selective availability not being turned on again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And not all aircraft have GPS anyway. So if you wanted to switch the ones that use GPS to true headings, there would still be some that would need to use the magnetic and it would be a mess. On the other hand when you have GPS, you have a computer already and it can contain and use the magnetic declination tables to give you magnetic heading as well.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-15T14:03:41.827" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="18921" PostTypeId="1" AcceptedAnswerId="18925" CreationDate="2015-08-15T14:38:56.383" Score="3" ViewCount="340" Body="&lt;p&gt;$V_r$ is the speed at pilot should initiate rotation on take-off and $V_2$ is the safe climb-out speed. Pilots determine them for each take-off by looking them up in a table in POH or QRH or somewhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But somebody had to fill those tables in using flight tests and calculations. What are the criteria by which the values are selected?&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-15T16:57:02.013" Title="How are $V_r$ and $V_2$ determined?" Tags="&lt;aircraft-design&gt;&lt;v-speeds&gt;&lt;aircraft-development&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18922" PostTypeId="1" AcceptedAnswerId="18924" CreationDate="2015-08-15T15:10:07.377" Score="5" ViewCount="1686" Body="&lt;p&gt;The European Union does not permit the entry of several airlines in any of its member states. It does so to ensure the safety of its own airfields, as it feels that management of several airlines is not caring enough. How is this justified?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No such ban is implemented by any Middle-East or American country, which have a very good safety record. What are the EU's views on banning airlines?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2018-07-31T15:49:48.667" LastActivityDate="2018-07-31T15:49:48.667" Title="Why has the European Union banned several airlines?" Tags="&lt;safety&gt;&lt;airlines&gt;&lt;eu&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="18923" PostTypeId="2" ParentId="18849" CreationDate="2015-08-15T15:46:53.977" Score="9" Body="&lt;p&gt;The answer is somewhat unclear, as there is limited (but emerging) case law and regulation on the subject and the outcome would depend heavily on the details of the airspace violation. However, there are some principles that we can use to shape our understanding:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The FAA has jurisdiction over anything flying, including UAS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was most recently restated in the &lt;a href=&quot;http://www.ntsb.gov/legal/alj/OnODocuments/Aviation/5730.pdf&quot; rel=&quot;noreferrer&quot;&gt;NTSB decision in FAA v. Pirker&lt;/a&gt;. Combine the definition in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/A16147FC43C4F9B286257A9500451B45?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 91.1&lt;/a&gt;: &quot;&lt;em&gt;Aircraft&lt;/em&gt; means a device that is used or intended to be used for flight in the air&quot; with the &lt;em&gt;Applicability&lt;/em&gt; section in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/274AF2832B95D48F86257758006712CB?OpenDocument&quot; rel=&quot;noreferrer&quot;&gt;FAR 91.1(a)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...[T]his part prescribes rules governing the operation of aircraft (other than moored balloons, kites, unmanned rockets, and unmanned free balloons, which are governed by part 101 of this chapter, and ultralight vehicles operated in accordance with part 103 of this chapter) within the United States including the waters within 3 nautical miles of the U.S. coast. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We see then, that anything flying is regulated - either under part 91, 101, or 103. Since UAS are not regulated under part 101 or 103, they fall under Part 91. Finally, the FAA has authority to impose a civil penalty for violations of the FARs under &lt;a href=&quot;https://www.law.cornell.edu/uscode/text/49/46301&quot; rel=&quot;noreferrer&quot;&gt;49 U.S. Code § 46301&lt;/a&gt;. Note that an FAA certificate is not necessary for the FAA to assess a civil penalty: in the Pirker case, the FAA assessed its penalty on a Swiss citizen who did not hold a FAA certificate.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Finding the operator of a UAS is difficult&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finding the operator of a UAS is much harder than finding the operator of a piloted aircraft. The FAA was able to find and assess a penalty to Raphael Pirker because he posted &lt;a href=&quot;https://www.youtube.com/watch?v=OZnJeuAja-4&quot; rel=&quot;noreferrer&quot;&gt;a video&lt;/a&gt; he made flying the UAS online. In most situations where UAS were where they shouldn't have been, the operators either were never found or turned themselves in:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nytimes.com/2015/01/28/us/white-house-drone.html&quot; rel=&quot;noreferrer&quot;&gt;UAS crash-landed on the White House grounds&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ktla.com/2015/06/25/illegal-4-foot-drone-shut-down-aerial-firefight-over-lake-fire-forest-service/&quot; rel=&quot;noreferrer&quot;&gt;UAS interrupts wildfire-fighting activity&lt;/a&gt; - a &lt;a href=&quot;http://www.nbcnews.com/tech/innovation/california-officials-offer-75k-bounty-drones-n401021&quot; rel=&quot;noreferrer&quot;&gt;reward&lt;/a&gt; was offered for identifying the operator&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nbcnewyork.com/news/local/Unmanned-Drones-Fly-Dangerously-Close-Airplanes-Kennedy-Airport-283247661.html&quot; rel=&quot;noreferrer&quot;&gt;UAS reported by pilots on approach to KJFK&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Basically, if you're flying a UAS far enough away from yourself that a police officer can't see the remote in your hands, you're unlikely to be found if just your UAS is detected. UAS for personal use do not currently require registration or external markings. A &lt;a href=&quot;http://www.avweb.com/avwebflash/news/Students-Invent-Anti-Drone-System-224682-1.html&quot; rel=&quot;noreferrer&quot;&gt;recent research project&lt;/a&gt; proposes a tracking system - but would require &quot;affixing radio-frequency detection tags to [UAS].&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Actual enforcement would vary&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After all of that, what would happen if you did violate controlled or restricted airspace and were caught? This area is pretty fuzzy, and would depend strongly on a number of criteria, including severity and intent. The FAA's toolbox for airspace violations is broad, but is generally tuned toward certificated pilots. A certificated pilot who accidentally entered class B airspace might get anything from a slap on the wrist, to a required training session with an instructor, to a short-term suspension of their certificate, based on the situation: an overwhelmed or confused pilot would get more leeway than one who just wasn't paying attention or was reckless in their navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suspension and required training are not really in the FAA's toolbox for folks without a certificate, so you likely would expect some sort of monetary fine. The FAA is limited to $10,000 in its fines, so you could not be charged more than that, and could well see something less. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Prevention is the best cure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some UAS manufacturers are building in &lt;a href=&quot;http://www.dji.com/fly-safe/category-mc&quot; rel=&quot;noreferrer&quot;&gt;safety restictions&lt;/a&gt; on their aircraft to prevent them from flying near airports (note that, at least in the linked situation, the restricted areas are less restrictive than B airspace, so would not necessarily keep you out of that airspace.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA is also working on a &lt;a href=&quot;http://www.faa.gov/uas/b4ufly/&quot; rel=&quot;noreferrer&quot;&gt;mobile app&lt;/a&gt; which should easily allow UAS operators to determine areas to avoid. This is relevant to the enforcement situation: if you enter airspace without clearance, but the app said it was OK, that would be a mitigating factor. More to the point, the app would provide information about the status of nearby airspace, allowing you to avoid violation, and the associated penalty, altogether.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2015-08-16T16:17:03.907" LastActivityDate="2015-08-16T16:17:03.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18924" PostTypeId="2" ParentId="18922" CreationDate="2015-08-15T15:53:08.783" Score="11" Body="&lt;p&gt;I think the policy is completely justified. An analogy: You wouldn't allow an unsafe and unapproved car onto a highway in Europe where it presents a unjust danger to everybody else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have to remember that the European Union is a fairly compact bunch of nations: To get to Paris from Southeast Asia or Africa, you're probably looking at overflying at least two or three other countries. Thus, a single flight will have wider implications and involve multiple nations. The policy keeps everybody somewhat happy that they have safe airlines in their airspace. It also keeps their own citizens off the airline in question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not think that it is a question of 'caring'. If they do not feel that the airline can safely fly, they ban it. Note that a fair number of the EU blacklist are automatically banned by country if they have insufficient oversight. It's also not a permanent 'thing' or sentence. Garuda Indonesia was on the EASA blacklist for two years until they brushed up, and are now back flying into the EU. Perhaps it might even have been good, since it pushed the company to improve their standards?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a recent quote on the Iraqi Airlines ban:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ATW understands from unidentified sources that 600 non-EU airlines had applied for TCO authorization. Most had been granted with few problems, but a small number of airlines were subject to greater scrutiny because of their perceived high-risk status. &lt;a href=&quot;http://atwonline.com/regulation/iraqi-airways-banned-european-airspace&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While perhaps less prominent, I think the United States will quickly block any unsafe airline from coming in, although perhaps on a more case-by-case basis. I believe there are other hurdles, such as airport security requirements, that have to be settled to fly into the United States and can act as barriers. I believe the same applies for any other nation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other countries say no as well, just perhaps not being as 'vocal': &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some Thai-registered airlines earlier faced flight restrictions by Japan, South Korea and Indonesia, following an audit of Thailand's air operations by the UN-based International Civil Aviation Organisation. In June the agency raised a red flag over aviation safety standards and gave the country until November to tackle the issue. Meanwhile, the US Federal Aviation Administration (FAA) last Friday gave Thailand 65 days to address shortcomings it had found. &lt;a href=&quot;http://www.bangkokpost.com/news/general/631668/prepare-for-bans-aot-tells-airports&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-08-15T16:05:21.810" LastActivityDate="2015-08-15T16:05:21.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18925" PostTypeId="2" ParentId="18921" CreationDate="2015-08-15T15:53:46.350" Score="3" Body="&lt;p&gt;The limits of the $V_{r}$ and $V_{2}$ are determined by the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d971bef1e10197ebb42c7912d4baec1a&amp;amp;node=14:1.0.1.3.11.2.155&amp;amp;rgn=div7&quot; rel=&quot;nofollow&quot;&gt;regulations&lt;/a&gt; in place. The rotation speed is the speed at which the pilot can the aircraft rotation for take off even when one engine is inoperative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consequently, this speed should be more than the minimum control speed with one engine inoperative, $V_{MC}$. The current regulations stipulate that the $V_{r}$ should be at least 1.05 times $V_{MC}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The safe climb out speed or takeoff climb speed is the speed which the aircraft should have reached at a given altitude. As per FAA regulations, this height is 35 feet above the takeoff surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aerospaceweb.org/question/performance/q0088.shtml&quot; rel=&quot;nofollow&quot;&gt;climb out speed&lt;/a&gt; $V_{2}$ should be at least 20% greater than the stall speed $V_{s}$ and 10% greater than $V_{MC}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=d0fda67fb6936d1e852108038d2423e3&amp;amp;mc=true&amp;amp;n=sp14.1.25.b&amp;amp;r=SUBPART&amp;amp;ty=HTML#se14.1.25_1111&quot; rel=&quot;nofollow&quot;&gt;FAA regulations&lt;/a&gt; prohibit lifting the nose landing gear before reaching $V_{r}$ and retracting it till the aircraft is completely airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircrafts undergo these tests during their certification process and these data is used by the pilots. Another thing is that both $V_{r}$ and $V_{2}$ are given in terms of &lt;em&gt;calibrated&lt;/em&gt; air speed.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2015-08-15T16:57:02.013" LastActivityDate="2015-08-15T16:57:02.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18926" PostTypeId="1" AcceptedAnswerId="18929" CreationDate="2015-08-15T17:16:44.050" Score="2" ViewCount="1305" Body="&lt;p&gt;In &lt;a href=&quot;https://www.google.co.uk/maps/place/Suvarnabhumi+Airport/@13.6919938,100.7516928,2106m/data=!3m1!1e3!4m2!3m1!1s0x311d67771542274f:0x120d19554f157a07&quot; rel=&quot;nofollow noreferrer&quot;&gt;Suvarnabhumi Airport&lt;/a&gt; (Bangkok) there is a building in aerodrome, next to the main terminal (Circle by red colour) . What is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HfPVb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HfPVb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-08-16T05:48:54.770" Title="What is that building in Suvarnabhumi Airport?" Tags="&lt;airport-design&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18929" PostTypeId="2" ParentId="18926" CreationDate="2015-08-15T19:05:40.433" Score="14" Body="&lt;p&gt;On page 5 of &lt;a href=&quot;http://www.aisthai.aviation.go.th/webais/pdf/AD%20vol1-CHART/VTBS[27].pdf&quot;&gt;current airport chart&lt;/a&gt; states it is Transfer Baggage Terminal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was officially opened on 1 November 2014 and reduce baggage transfer time from 75 minutes to 60 minutes. It was constructed above South Airside Tunnel between gate C, D and E and has usable space of about 12,550 sq.m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://suvarnabhumiairport.com/en/news/448/%E0%B8%97%E0%B9%88%E0%B8%B2%E0%B8%AD%E0%B8%B2%E0%B8%81%E0%B8%B2%E0%B8%A8%E0%B8%A2%E0%B8%B2%E0%B8%99%E0%B8%AA%E0%B8%B8%E0%B8%A7%E0%B8%A3%E0%B8%A3%E0%B8%93%E0%B8%A0%E0%B8%B9%E0%B8%A1%E0%B8%B4%E0%B9%80%E0%B8%9B%E0%B8%B4%E0%B8%94%E0%B9%83%E0%B8%8A%E0%B9%89%E0%B8%AD%E0%B8%B2%E0%B8%84%E0%B8%B2%E0%B8%A3-transfer-baggage-terminal-%E0%B8%AA%E0%B8%B3%E0%B8%AB%E0%B8%A3%E0%B8%B1%E0%B8%9A%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%82%E0%B8%94%E0%B8%A2%E0%B8%AA%E0%B8%B2%E0%B8%A3%E0%B9%80%E0%B8%9B%E0%B8%A5%E0%B8%B5%E0%B9%88%E0%B8%A2%E0%B8%99%E0%B9%80%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B8%A2%E0%B8%A7%E0%B8%9A%E0%B8%B4%E0%B8%99%E0%B9%81%E0%B8%A5%E0%B9%89%E0%B8%A7&quot;&gt;Source&lt;/a&gt; (Sorry source is in Thai. My own translation.)&#xA;&lt;Br&gt;Another &lt;a href=&quot;http://www.mcot.net/site/content?id=5466dca0be0470b9cc8b472d#.VdAGcMsaySO&quot;&gt;source&lt;/a&gt; in English. Similar to my original source.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="679" LastEditDate="2015-08-16T05:48:54.770" LastActivityDate="2015-08-16T05:48:54.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18930" PostTypeId="1" CreationDate="2015-08-15T20:17:49.603" Score="17" ViewCount="3293" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/18905/755&quot;&gt;voretaq7's answer&lt;/a&gt; to the question &lt;a href=&quot;https://aviation.stackexchange.com/q/18903/755&quot;&gt;Is there a name for the area for aircraft to back track near the runway threshold?&lt;/a&gt;, it is mentioned that runway turnaround areas are considered part of the runway to which they are attached and that any aircraft in the turnaround zone are considered to occupy the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I noticed that in the picture provided in his answer showing a runway turnaround area, the runway edge stripes actually included the runway turnaround area:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/f0K8d.jpg&quot; alt=&quot;Runway with turnaround area&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I've also noted that at the small, uncontrolled GA airport I've most often flown from, the runway edge stripes &lt;em&gt;do not&lt;/em&gt; include the turnaround area:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/mp24J.jpg&quot; alt=&quot;Arrival end of 8A3&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, in either case, a departing aircraft must cross the runway hold line and enter the runway to back-taxi to the turnaround area in the first place. However, I'm curious &lt;strong&gt;under what, if any, circumstances is it legal under the U.S. FARs for an aircraft to land or take off on a runway while another aircraft occupies the turn-around zone on that runway?&lt;/strong&gt; And, of course, I'm talking about normal operations here, not emergencies.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the runway edge stripe configuration matter, for example?&lt;/li&gt;&#xA;&lt;li&gt;How does this differ between controlled and uncontrolled fields?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the sake of simplicity, let's assume that both aircraft in question are light GA aircraft, not aircraft whose wings might stick off the sides of the runway, and that all parts of the aircraft in the turnaround zone are on the turnaround side of where the runway edge line would be were it a straight line (like it is in the second picture.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen both landings and takeoffs with another aircraft in the turnaround area at the bottom field pictured above, including a couple of aircraft back-taxiing out there (under mutual agreement and while in radio communication with each other) and the second of them wait in the turnaround while the first takes off.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-18T17:06:11.473" Title="In the U.S., Is it ever legal for an aircraft to occupy the runway turnaround area while another is taking off or landing?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18931" PostTypeId="2" ParentId="18922" CreationDate="2015-08-15T20:53:48.473" Score="6" Body="&lt;p&gt;The project existed earlier but there is a clear and immediate reason for the creation of the first EU “black list”, it's the &lt;a href=&quot;https://en.wikipedia.org/wiki/West_Caribbean_Airways_Flight_708&quot; rel=&quot;noreferrer&quot;&gt;West Caribbean Airways Flight 708&lt;/a&gt;. The crash created a lot of emotion in France. &lt;a href=&quot;http://www.theguardian.com/world/2005/aug/19/shopping.transport&quot; rel=&quot;noreferrer&quot;&gt;Here is a Guardian article from the time&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After that crash, the EU felt the need to be seen as “doing something”, especially since many passengers might not even have realized they booked a ticket on flight operated by some unknown third-country carrier. You can debate the wisdom of the approach or many other details of the current rules but the timeline is clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the EU did not invent the concept, other countries (and also EU members states) did and do ban airlines from operating on their territories. And the justification is indeed that these airlines have serious deficiencies in their fleet, management and procedures. Even if you are personally not convinced, why would you expect that any other justification would be needed?&lt;/p&gt;&#xA;" OwnerUserId="3018" LastActivityDate="2015-08-15T20:53:48.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18932" PostTypeId="2" ParentId="18912" CreationDate="2015-08-15T21:43:02.190" Score="6" Body="&lt;p&gt;The maneuvering airspeed $v_A$ ensures that the maximum structural load is not exceeded even with maximum control surface deflection. Wikipedia says this is valid only when a single control surface is maximally deflected, but really the regulations try to make sure that any combination of single control inputs is safe. To determine the structural load, one must know the mass of all non-lift-creating parts. Fuel in the wing tanks does not count, as it is carried by the lift created right around it and does not increase the wing root bending moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given: A maximum wing root bending moment $M_{b_{max}}$, a maximum load factor $n_{z_{max}}$, a maximum lift coefficient $c_{L_{max}}$ and a gross mass of all parts supported by the wing (fuselage, payload, fuselage-mounted engine, …) of $m_{nlc}$. Further, let's assume that the center of lift of one wing with the area $½S$ is out at a wing station $y_L$ (to be precise, use the center of lift with maximum down aileron deflection, measured from the attachment point of the wing at the fuselage), and the mass of the wings (plus fuel in the wing tanks and engines on the wing) is $m_{total} - m_{nlc}$. The lift of one wing is&#xA;$$L = ½S\cdot\rho\cdot ½v^2\cdot c_{L_{max}}$$&#xA;and the root bending moment is&#xA;$$M_b = \left(L - ½(m_{total} - m_{nlc})\cdot n_z\right)\cdot y_L$$&#xA;Note that the bending moment ist not just lift times lever arm, but is reduced by the part of the airplane's mass which is contained in the lift-creating parts, all calculated for one side!&#xA;The maximum allowable speed at which this bending moment reaches the maximum allowed value is&#xA;$$v_A = \sqrt{\frac{4\cdot\frac{M_{b_{max}}}{y_L}+2\cdot(m_{total} - m_{nlc})\cdot n_{z_{max}}}{S\cdot\rho\cdot c_{L_{max}}}}$$&#xA;Now you need only to know how the total flight mass $m_{total}$ of your aircraft is divided between what is carried at the wing root and what is the wing and attached to it. Increasing the payload carried in the fuselage, or adding fancy equipment in the cockpit will reduce $v_A$, and increasing fuel in the wing tanks will have no effect. If you add mass outside of $y_L$ (like with tip tanks), the bending load is decreased and $v_A$ goes up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that conditions exist where the maximum tolerable structural loads can be exceeded even at $v_A$: If the pilot moves one control surface repeatedly with the eigenfrequency of a structural or a rigid-body eigenmode, the aircraft can build up angles of attack beyond those achievable with a single input. Consequently, the stresses can grow above those used for sizing the structure.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="8490" LastEditDate="2015-08-24T21:57:48.477" LastActivityDate="2015-08-24T21:57:48.477" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="18934" PostTypeId="1" AcceptedAnswerId="18937" CreationDate="2015-08-16T01:36:36.317" Score="6" ViewCount="5257" Body="&lt;p&gt;While reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/17221/why-do-trijets-3-rear-engines-usually-have-a-t-tail-instead-of-a-normal-tail&quot;&gt;this question&lt;/a&gt; about trijets I started wondering why the center engine in the DC10 and MD11 where placed where they are. Most trijets have the center engine at the very back of the fuselage with the intake in front of the vertical stabilizer. The DC10/MD11 engine is placed above the fuselage at the bottom of the vertical stab. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering if there is some advantage to that. Does placing the engine there create an appreciable pitch down moment? And how would that relate to the pitch up moment of the underwing engines? Are there any other aircraft that have this configuration?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="62" LastEditDate="2019-01-08T02:34:36.570" LastActivityDate="2019-03-27T21:28:00.307" Title="Why is the DC10/MD11 center engine placed where it is?" Tags="&lt;aircraft-design&gt;&lt;dc-10&gt;&lt;md-11&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18935" PostTypeId="1" AcceptedAnswerId="18938" CreationDate="2015-08-16T02:20:11.943" Score="7" ViewCount="264" Body="&lt;p&gt;How should operations be conducted at an airport with an operating control tower that is in Class E (controlled) or Class G (uncontrolled) airspace? Is this topic covered in an FAA publication such as the Aeronautical Information Manual (AIM) or Pilot's Handbook of Aeronautical Knowledge (PHAC)?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-08-16T14:00:56.080" LastActivityDate="2015-08-16T20:59:10.430" Title="How should operations be conducted at a towered airport that is in uncontrolled airspace?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18936" PostTypeId="1" AcceptedAnswerId="18939" CreationDate="2015-08-16T02:44:34.933" Score="2" ViewCount="403" Body="&lt;p&gt;The Cruise-Efficient Short Take Off and Landing (CESTOL) is a NASA project.  There is a &lt;a href=&quot;https://www.youtube.com/watch?v=Sa-w6M5UR5U&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Sa-w6M5UR5U?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The configuration is a conventional fuselage at the very front of the aircraft with enormous thick section leading edge extensions.  The wings outside the LEX appear to have similar aspect ratio to a 737 or A320.  The aft fuselage is flattened and there is a v-tail.  The engines are buried in the wings in a fashion similar to the Gloster Meteor aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much less or more efficient would this configuration be compared to a conventional tube and wing configuration for a 737/A320 size aircraft given similar engines and materials?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="15311" LastEditDate="2019-02-24T13:50:35.653" LastActivityDate="2019-02-24T13:50:35.653" Title="Could the Cruise-Efficient STOL configuration be as efficient as a conventional airliner?" Tags="&lt;aircraft-design&gt;&lt;stol&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="18937" PostTypeId="2" ParentId="18934" CreationDate="2015-08-16T02:58:58.903" Score="9" Body="&lt;p&gt;There are a few ways the aircraft engines can be mounted on the centerline, each with its advantages and disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QnLVM.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QnLVM.gif&quot; alt=&quot;Taken from http://adg.stanford.edu/aa241/propulsion/engineplacement.html&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Image from &lt;a href=&quot;https://web.archive.org/web/20161203020212/http://adg.stanford.edu/aa241/propulsion/engineplacement.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stanford University&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way is to mount them as in DC10, with engine above the fuselage; another one is to use a 'S' shaped inlet and put the engine at the aft of the fuselage like &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Falcon_7X&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassault Falcon 7X&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of mounting the engine as in DC10 is that the inlet distortion is minimized and there is no need to cut a hole through the fuselage for putting engine. The main disadvantages are that it increases drag (slightly) and engine maintenance is a mess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently,the DC10 engineers &lt;a href=&quot;https://web.archive.org/web/20161203020212/http://adg.stanford.edu/aa241/propulsion/engineplacement.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;tried&lt;/a&gt; to put all three engines in the wing during design, but were not successful. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines mounted in high thrust line like DC10 and &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-47_PiperJet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper PA47&lt;/a&gt; are highly stabilizing as increase in engine thrust causes a pitch down motion as the thrust is increased. This is usually disconcerting to the pilots, who expect the aircraft to pitch up while engine power is increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally they ended up adding &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2009/July/28/Nozzle-mutes-PiperJet-pitch-changes&quot; rel=&quot;nofollow noreferrer&quot;&gt;design changes&lt;/a&gt; to correct this in PA47 (to make it pitch neutral). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In DC10, a combination of underwing and high thrust line engines would've most probably caused no pitch changes at all. So I guess the main advantage is reducing inlet distortion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As MD11 was developed from DC10, it simply inherited this design. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: As for the pitch down moment being disconcerting to the pilots, it is better if someone corroborates it. It is simply that most aircraft don't do this.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="946" LastEditDate="2019-03-27T21:28:00.307" LastActivityDate="2019-03-27T21:28:00.307" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="18938" PostTypeId="2" ParentId="18935" CreationDate="2015-08-16T03:04:03.743" Score="8" Body="&lt;p&gt;Airport with an operating control tower = talk to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the regulations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;§91.126(d) (concerns Class G) and §91.127(c) (concerns Class E) are identical.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Communications with control towers.&lt;/em&gt; Unless otherwise authorized or required by ATC, no person may operate an aircraft to, from, through, or on an airport having an operational control tower unless two-way radio communications are maintained between that aircraft and the control tower. Communications must be established prior to 4 nautical miles from the airport, up to and including 2,500 feet AGL. However, if the aircraft radio fails in flight, the pilot in command may operate that aircraft and land if weather conditions are at or above basic VFR weather minimums, visual contact with the tower is maintained, and a clearance to land is received. If the aircraft radio fails while in flight under IFR, the pilot must comply with §91.185.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-16T03:04:03.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18939" PostTypeId="2" ParentId="18936" CreationDate="2015-08-16T04:40:08.907" Score="4" Body="&lt;p&gt;Without data, it is not possible to tell if one design will be better than another. This is because it is one thing to make a concept (which this is) and entirely another thing to manufacture and operate the aircraft (like A320/737).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, the design in the video is not entirely new, It is similiar to the Boeing YC 14&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wULGh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wULGh.jpg&quot; alt=&quot;Boeing YC 14&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;developed for UASF AMST program. It is instructive to note what happened in that program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AMST program was initiated for developing a tactical STOL aircraft, requirements similar to the CESTOL. Even though YC 14 met the requirements, the program was scrapped for other reasons and the C17 was developed from another contender in AMST program, the YC15.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even during development fo the YC14, the drag was more than expected and Boeing struggled to bring it under control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I doubt the design as shown is ever going to be made into an actual aircraft. There are too many problems at first glance&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The wing seems to pass right through the fuselage. This is not going to work in a transport aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The location of the engines suggest that the main spar will pass right through it. This will have strength implications.&lt;/li&gt;&#xA;&lt;li&gt;In case the aircraft is used for STOL operations, the rear fuselage design should be redesigned for preventing tail strike as the landing gear in all probability will be shorter.&lt;/li&gt;&#xA;&lt;li&gt;Putting the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet#Design&quot; rel=&quot;nofollow noreferrer&quot;&gt;engine inside wing&lt;/a&gt; is not a great idea as it increases complexity and chances of catastrophic wing failure.  &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;There are a number of &lt;a href=&quot;http://www.popsci.com/technology/article/2013-06/future-flight-new-designs-will-end-congestion&quot; rel=&quot;nofollow noreferrer&quot;&gt;similar&lt;/a&gt; programs for developing efficient STOL aircraft, none of which have come into fruition. It is going to to be the economics of the operation from small airports, rather than the aircraft itself, which will decide if these designs will ever see the light of day, let alone operate in commercial routes.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3825" LastEditDate="2015-08-16T19:57:05.880" LastActivityDate="2015-08-16T19:57:05.880" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18940" PostTypeId="1" AcceptedAnswerId="18942" CreationDate="2015-08-16T06:57:12.270" Score="25" ViewCount="11116" Body="&lt;p&gt;I was reading about &lt;a href=&quot;http://www.dgiglobal.com/classes&quot;&gt;Dangerous Goods&lt;/a&gt;, and came across the fact that magnetized materials are classified as Dangerous Goods (item 12 in the linked page). We all see magnets every day, and they seem harmless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are magnets dangerous to airplanes and require more careful handling?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="1961" LastEditDate="2015-08-16T20:55:47.050" LastActivityDate="2018-03-30T23:55:51.850" Title="Why are magnetized materials dangerous goods?" Tags="&lt;safety&gt;&lt;cargo&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18941" PostTypeId="2" ParentId="18940" CreationDate="2015-08-16T07:32:48.940" Score="17" Body="&lt;p&gt;Because the aircraft has a standby compass in the cockpit which is a normal magnetic compass.  This compass must be fitted and must be working in case of extreme instrument failure.  There are three things which standby instruments must provide; height, speed and heading (the compass).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Magnetic cargo can interfere with this compass and therefore, is treated as dangerous cargo.  Whilst the risk is low, the aviation industry leans on the side of safety, and we can all see the benefits of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/safety/DangerousGoods/DGP%2022%20Working%20Papers/DGP.22.WP.042.2.en.pdf&quot;&gt;This report will tell you what you want to know.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-08-16T07:32:48.940" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="18942" PostTypeId="2" ParentId="18940" CreationDate="2015-08-16T07:33:14.243" Score="21" Body="&lt;p&gt;98% percent of magnets - the everyday ones - are completely harmless. I believe the concern is with super-strong &lt;a href=&quot;https://en.wikipedia.org/wiki/Rare-earth_magnet&quot;&gt;rare-earth magnets&lt;/a&gt;, where they can be problematic. Aside from Simon's valid point on interference to compasses:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Getting stuck to things, such as other bags or the infrastructure itself, in the baggage system.&lt;/li&gt;&#xA;&lt;li&gt;Attract themselves to other packages and content, possibly damaging these. Think of hard drives and electronics.&lt;/li&gt;&#xA;&lt;li&gt;Being a nuisance and safety concern should somebody decide to open it, such as customs or security. You can get your hand crushed in the process if you open the box and the thing springs out.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Be aware they do not appear to be banned - just regulated in that they have to be properly labelled and packaged for safe transport. More curiously in that list are 'First Aid Kits' and 'Seatbelt Pretensioners'.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="849" LastEditDate="2015-08-16T20:25:24.163" LastActivityDate="2015-08-16T20:25:24.163" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="18943" PostTypeId="1" AcceptedAnswerId="18944" CreationDate="2015-08-16T08:20:40.913" Score="8" ViewCount="1240" Body="&lt;p&gt;Given that runways are labelled by magnetic heading. What happens in airports that have more than one in the same direction?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are they labelled?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any such airports?&lt;/p&gt;&#xA;" OwnerUserId="9417" LastActivityDate="2016-08-11T07:45:39.237" Title="More than one runway with the same heading. How are they labelled?" Tags="&lt;runways&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-08-16T19:37:01.430" ContentLicense="CC BY-SA 3.0" />
  <row Id="18944" PostTypeId="2" ParentId="18943" CreationDate="2015-08-16T08:32:08.407" Score="13" Body="&lt;p&gt;Left, right and centre.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Heathrow has 27 left (27L) and right and 09 left (09L) and right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ead.eurocontrol.int/eadbasic/pamslight-5521D60A1DDE32D1DA7D2186A978F78D/7FE5QZZF3FXUS/EN/Charts/AD/AIRAC/EG_AD_2_EGLL_2-1_en_2015-05-28.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;See here for the airfield chart.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.co.uk/maps/place/Heathrow+Airport/@51.4773308,-0.4335103,238m/data=!3m1!1e3!4m2!3m1!1s0x48767234cdc56de9:0x8fe7535543f64167!6m1!1e1&quot; rel=&quot;nofollow noreferrer&quot;&gt;You can see the numbers close to the end of the runways.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example for an airfield with a 34 left runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MBICk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MBICk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there are more than three runways more or less parallel, one or more runway numbers will be shifted by 10 degrees, e.g. 08L, 08C, 08R, 09R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Wikipedia article on runway numbering:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At large airports with four or more parallel runways (for example, at&#xA;  Los Angeles, Detroit Metropolitan Wayne County, Hartsfield-Jackson&#xA;  Atlanta, Denver, Dallas-Fort Worth and Orlando) some runway&#xA;  identifiers are shifted by 10 degrees to avoid the ambiguity that&#xA;  would result with more than three parallel runways. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For example, in Los Angeles, this system results in runways 6L, 6R,&#xA;  7L, and 7R, even though all four runways are actually parallel&#xA;  (approximately 69 degrees). At Dallas/Fort Worth International&#xA;  Airport, there are five parallel runways, named 17L, 17C, 17R, 18L,&#xA;  and 18R, all oriented at a heading of 175.4 degrees. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Occasionally, an airport with only 3 parallel runways may use&#xA;  different runway identifiers, for example when a third parallel runway&#xA;  was opened at Phoenix Sky Harbor International Airport in 2000 to the&#xA;  south of existing 8R/26L, rather than confusingly becoming the &quot;new&quot;&#xA;  8R/26L it was instead designated 7R/25L, with the former 8R/26L&#xA;  becoming 7L/25R and 8L/26R becoming 8/26.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-08-11T07:45:39.237" LastActivityDate="2016-08-11T07:45:39.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18945" PostTypeId="1" CreationDate="2015-08-16T11:17:05.937" Score="0" ViewCount="580" Body="&lt;p&gt;How can a plane just go missing? It's mad surely with the technology these days they could at least pin point the location of a plane. We have the technology to transmit pictures of Pluto back to Earth million miles but a plane goes missing and can't be found?! Even if my iPhone got lost, I'll be able to have an app locate it for me. &lt;/p&gt;&#xA;" OwnerUserId="9819" LastActivityDate="2015-08-16T14:06:25.020" Title="With today's technology, why can't we find crashed planes" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-08-16T15:20:09.220" ContentLicense="CC BY-SA 3.0" />
  <row Id="18946" PostTypeId="2" ParentId="18945" CreationDate="2015-08-16T11:58:56.147" Score="1" Body="&lt;p&gt;Having a technology and using it are two different things. As already noted, you are able to get pictures from Pluto because your tracking station knows where it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, the aircraft position is determined by Primary Radar, which literally scans the sky, but its effective range is limited and they are costly to operate. The secondary Radar locates the aircraft by interrogating its transponder, which provides the ATC with its location and speed. However, if the transponder is not working, there is no way for to detect the aircraft locations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft can also communicate with the ground station using ACARS, but it depends on on board electrical system. The same goes for the ADS-B, which depends on onboard systems for determining its location and speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its a bit like trying to find your mobile after switching it off. No app is going to work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that the aircraft is involved in a crash, the Emergency Locator Transmitter (ELT) can be used to trace the aircraft. However, these are not mandatory in scheduled flights(though ULB is mandatory).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Satellites could help, but again, they should know where to look for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wifi or working mobile phones onboard could help, but these are yet to be implemented in any big way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next generation technologies under development will allow  real time tracking of the aircraft, but these are still under development.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-16T11:58:56.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18947" PostTypeId="2" ParentId="203" CreationDate="2015-08-16T12:22:12.320" Score="3" Body="&lt;p&gt;Sometimes the sun is setting directly over the end of the runway with the headwind. Definitely a challenge, and it is a wise decision to land in the other direction unless the tailwind isn't too strong. If it's a controlled airport, you have to get a clearance for that of course. &lt;/p&gt;&#xA;" OwnerUserId="9820" LastEditorUserId="97" LastEditDate="2015-08-16T18:13:12.393" LastActivityDate="2015-08-16T18:13:12.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18948" PostTypeId="2" ParentId="18945" CreationDate="2015-08-16T14:06:25.020" Score="0" Body="&lt;p&gt;While the other points are valid the other consideration is that between an observer on the correct side of the Earth and Pluto there is a couple of miles of air and then miles and miles of absolutely nothing which is no obstacle to light or radio waves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking for a lost plane there is a better than 2/3 chance that it is under seawater which you cannot normally see more than a couple of feet through with visible light or RF, &lt;em&gt;(this is why submarines are so hard to find and have to use ULF to receive notification to surface for messages)&lt;/em&gt;.  Keep in mind that we have better maps of the moon than of the seabed.  From &lt;a href=&quot;http://www.noaa.gov/ocean.html&quot; rel=&quot;nofollow&quot;&gt;NOAA&lt;/a&gt;: &quot;The ocean covers 71 percent of the Earth's surface and contains 97 percent of the planet's water, yet more than 95 percent of the underwater world remains unexplored.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you are on a flat level stretch of ground the horizon is only about 3 miles away when standing on the ground so a parked airplane 5 miles away would be invisible on a flat featureless grassland.&lt;/p&gt;&#xA;" OwnerUserId="9821" LastActivityDate="2015-08-16T14:06:25.020" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18949" PostTypeId="2" ParentId="203" CreationDate="2015-08-16T16:18:49.380" Score="2" Body="&lt;p&gt;When I flew light airplanes in Alaska there were a few one-way-in-one-way-out strips that I would take the tailwind before departing.  Very common in some parts of the world.&lt;/p&gt;&#xA;" OwnerUserId="9822" LastEditorUserId="97" LastEditDate="2015-08-16T18:10:23.543" LastActivityDate="2015-08-16T18:10:23.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18950" PostTypeId="1" AcceptedAnswerId="59498" CreationDate="2015-08-16T16:25:34.973" Score="19" ViewCount="6875" Body="&lt;p&gt;A quote from &lt;a href=&quot;http://gizmodo.com/5893817/the-concordes-soviet-older-sister-that-just-couldnt-stop-crashing&quot;&gt;this article&lt;/a&gt;:  &quot;The Concorde had better range, braking and engine control but the Tupolev had vastly superior aerodynamics.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the basis, if any, for this statement on the aerodynamics of the two aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="22726" LastEditDate="2019-01-24T03:48:38.270" LastActivityDate="2019-11-15T21:02:11.370" Title="Why is it said that the Tupolev Tu-144 had superior aerodynamics to the Concorde?" Tags="&lt;aircraft-design&gt;&lt;concorde&gt;&lt;tu-144&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18951" PostTypeId="1" AcceptedAnswerId="18952" CreationDate="2015-08-16T18:12:06.457" Score="50" ViewCount="19509" Body="&lt;p&gt;I've noticed that Boeing 737-800's cockpit has a 3-position landing gear lever. During takeoff, the pilot moves the lever from DOWN to UP and then to OFF position. What's the point of the OFF position? Why not simply have UP/DOWN positions?&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="97" LastEditDate="2015-08-16T18:16:19.713" LastActivityDate="2019-08-29T05:39:26.287" Title="Why does the landing gear control have 3 positions (up/down/off) on Boeing 737-800?" Tags="&lt;landing-gear&gt;&lt;boeing-737&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="18952" PostTypeId="2" ParentId="18951" CreationDate="2015-08-16T18:19:10.393" Score="31" Body="&lt;p&gt;When UP or DOWN is selected, the hydraulics pressurize in the appropriate direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the gear is up and the mechanical locks are keeping the gear locked in place, OFF can be selected to disconnect the hydraulic power.&lt;/p&gt;&#xA;" OwnerUserId="97" LastEditorUserId="11215" LastEditDate="2018-09-19T23:05:36.043" LastActivityDate="2018-09-19T23:05:36.043" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="18953" PostTypeId="1" AcceptedAnswerId="18955" CreationDate="2015-08-16T19:03:19.490" Score="3" ViewCount="2654" Body="&lt;p&gt;Do runways always handle traffic in the same direction? Another question asked how runways were &lt;a href=&quot;https://aviation.stackexchange.com/questions/18943/more-than-one-runway-with-the-same-heading-how-are-they-labelled&quot;&gt;labelled&lt;/a&gt; left and right (8L and 8R, for example). But of course &quot;left&quot; and &quot;right&quot; depend on your perspective. If you were approaching from the opposite direction, then left would be right and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this mean that runways only handle traffic coming from the same direction all of the time? Are there no ambidextrous runways that flip depending on the prevailing winds or whims of ATC? &lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-17T19:00:58.967" Title="Are runways &quot;one-way&quot;?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-16T21:26:08.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="18954" PostTypeId="2" ParentId="17221" CreationDate="2015-08-16T19:04:57.500" Score="2" Body="&lt;p&gt;You can't have a horizontal stabilizer where the engines are mounted. It's either one or the other at this location.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2015-08-16T19:04:57.500" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18955" PostTypeId="2" ParentId="18953" CreationDate="2015-08-16T19:09:58.410" Score="10" Body="&lt;p&gt;As noted in the linked question to the question you linked to (&lt;a href=&quot;https://aviation.stackexchange.com/questions/65/how-are-runways-numbered&quot;&gt;this one&lt;/a&gt;), runways are almost always bidirectional. In your example, the other runway would be simply numbered 18 higher or lower, for 180 degrees off. Thus, the runways would be 26R and 26L - the &quot;L&quot; and &quot;R&quot; would swap, because you are pointed at them the opposite way. You can see this in the diagram of LAX below (&lt;a href=&quot;http://rwsl.ll.mit.edu/Image-Lib/LAX/LAX-diagram.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;src&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Yc9Qr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Yc9Qr.jpg&quot; alt=&quot;LAX&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, generally they flip based on prevailing winds, though I can't imagine they flip based on the &quot;whims&quot; of ATC often. Most airports will have a &quot;calm wind runway&quot;, which is the preferred runway for operations in calm or near-calm winds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to terrain or similar factors, some runways may be only usable one direction, but both directions will still be numbered, as you will takeoff and land pointing different directions (for example, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenzing-Hillary_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lukla airport&lt;/a&gt; in Nepal). Alternatively, as Jan Hudec noted, some will operate one-way, such as &lt;a href=&quot;https://www.airnav.com/airport/TNCM&quot; rel=&quot;nofollow noreferrer&quot;&gt;TNCM&lt;/a&gt;, though again, both runways are numbered. Occasionally, the opposite direction is not numbered, though this is rare.&lt;/p&gt;&#xA;" OwnerUserId="774" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-17T19:00:58.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18956" PostTypeId="2" ParentId="18912" CreationDate="2015-08-16T19:30:31.023" Score="7" Body="&lt;p&gt;Compute maneuvering speed below max gross using the formula &lt;span class=&quot;math-container&quot;&gt;$V_A\sqrt{\frac{W_2}{W_1}}$&lt;/span&gt;, where &lt;span class=&quot;math-container&quot;&gt;$V_A$&lt;/span&gt; is the maneuvering speed at max gross, &lt;span class=&quot;math-container&quot;&gt;$W_2$&lt;/span&gt; is actual weight, and &lt;span class=&quot;math-container&quot;&gt;$W_1$&lt;/span&gt; is max gross.&lt;/p&gt;&#xA;&lt;p&gt;We can derive this relationship — or for any other V-speed such as stall speed of landing speed that varies with weight — from the lift equation. In steady-state flight, weight equals lift so&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$W_1 = \frac{1}{2} C_L \rho v_1^2 S$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;and likewise for &lt;span class=&quot;math-container&quot;&gt;$W_2$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$v_2$&lt;/span&gt;. Dividing the first by the second cancels the coefficients and leaves&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{W_1}{W_2} = \frac{v_1^2}{v_2^2}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Take the square root of both sides and solve for &lt;span class=&quot;math-container&quot;&gt;$v_2$&lt;/span&gt; to arrive at the general formula&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$v_2 = v_1 \sqrt{\frac{W_2}{W_1}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;John Denker provides an intuition for why the relationship works the way it does.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Unlike &lt;span class=&quot;math-container&quot;&gt;$V_{NO}$&lt;/span&gt;, the maneuvering speed varies in proportion to the square root of the mass of the airplane. The reason for this is a bit tricky. The trick is that &lt;span class=&quot;math-container&quot;&gt;$V_A$&lt;/span&gt; is not a force limit but rather an acceleration limit. When the manufacturers determine a value for &lt;span class=&quot;math-container&quot;&gt;$V_A$&lt;/span&gt;, they are not worried about breaking the wing, but are worried about breaking other important parts of the airplane, such as the engine mounts. These items don’t directly care how much force the wing is producing; they just care about the acceleration they are undergoing.&lt;/p&gt;&#xA;&lt;p&gt;By increasing the mass of the airplane, you decrease the overall acceleration that results from any overall force. (Of course, if you increase the mass of cargo, it increases the stress on the cargo-compartment floor — but it decreases the stress on unrelated components such as engine mounts, because the acceleration is less.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Later in the same section, Denker clarifies.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Finally, we should note that there are two different concepts that, loosely speaking, are called maneuvering speeds.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;em&gt;design&lt;/em&gt; maneuvering speed, which we can denote &lt;span class=&quot;math-container&quot;&gt;$V_{A(D)}$&lt;/span&gt;, is primarily of interest to aircraft designers, not pilots. The designer must choose a value for &lt;span class=&quot;math-container&quot;&gt;$V_{A(D)}$&lt;/span&gt; and then build an aircraft strong enough to withstand certain stressful maneuvers at that speed. Higher values of &lt;span class=&quot;math-container&quot;&gt;$V_{A(D)}$&lt;/span&gt; promote safety, by forcing the design to be stronger.&lt;/li&gt;&#xA;&lt;li&gt;The maneuvering speed &lt;em&gt;limitation&lt;/em&gt;, which we can denote &lt;span class=&quot;math-container&quot;&gt;$V_{A(L)}$&lt;/span&gt;, is of interest to pilots. It is an operating limitation. It appears on a placard in the cockpit. Lower values of &lt;span class=&quot;math-container&quot;&gt;$V_{A(L)}$&lt;/span&gt; promote safety, by restricting certain operations to lower, less-stressful airspeeds.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Denker, John S., &lt;em&gt;&lt;a href=&quot;http://www.av8n.com/how/&quot; rel=&quot;nofollow noreferrer&quot;&gt;See How It Flies&lt;/a&gt;&lt;/em&gt;, §2.14.2 “&lt;a href=&quot;http://www.av8n.com/how/htm/aoa.html#sec-maneuvering-speed&quot; rel=&quot;nofollow noreferrer&quot;&gt;Maneuvering Speed&lt;/a&gt;,” accessed 16 Aug 2015.&lt;/p&gt;&#xA;&lt;p&gt;The discussion above pertains to the maneuvering speed limitation, &lt;em&gt;i.e.&lt;/em&gt;, values a pilot would find in a POH or on placards. For example, the humble Cessna 152 POH shows &lt;span class=&quot;math-container&quot;&gt;$V_A$&lt;/span&gt; decreasing with decreasing weight: 104 KIAS at the max gross of 1,670 pounds, 98 KIAS at 1,500 pounds, and 93 KIAS at 1,350 pounds. The reader will also note that these values fit the general relationship given at the beginning of this answer.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-08-06T10:40:36.890" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="18957" PostTypeId="1" CreationDate="2015-08-16T19:34:20.253" Score="5" ViewCount="7716" Body="&lt;p&gt;What is the difference between &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_AH-1Z_Viper&quot; rel=&quot;nofollow&quot;&gt;Bell AH-1Z Viper&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_AH-64_Apache&quot; rel=&quot;nofollow&quot;&gt;Apache AH-64D Block III Longbow&lt;/a&gt; in terms of role? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When does someone use AH-1Z Viper and when does someone use AH-64D Block III?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="1467" LastEditDate="2017-12-20T12:44:11.390" LastActivityDate="2017-12-20T12:44:11.390" Title="What is the difference between Bell AH-1Z Viper and Apache Longbow in terms of role?" Tags="&lt;military&gt;&lt;helicopter&gt;&lt;ah-64&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18958" PostTypeId="2" ParentId="18935" CreationDate="2015-08-16T20:10:52.813" Score="5" Body="&lt;p&gt;Treat a class E or class G tower just as you would Class D. The only differences are Basic VFR minimums, 4nm undepicted area, and IFR procedures &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-08-16T20:59:10.430" LastActivityDate="2015-08-16T20:59:10.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18961" PostTypeId="2" ParentId="18871" CreationDate="2015-08-16T20:40:03.363" Score="1" Body="&lt;p&gt;Not only do copters fly instrument approaches, they are allowed by regulation to halve both the ceiling and visibility minima for a non-Copter approach (but no less than 1200 and 1/4, or as otherwise restricted).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, copters often convert an instrument approach at the Missed Approach Point into a Special VFR clearance, which allows them to fly with 0 visibility (see and avoid) and clear of clouds. For example, this approach into JFK terminated in the middle of NY Harbor at 500 feet, and  shows course lines to the various Manhattan helipads :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vf86Z.jpg&quot; alt=&quot;copter approach&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-16T20:40:03.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18962" PostTypeId="2" ParentId="18950" CreationDate="2015-08-17T01:14:37.173" Score="13" Body="&lt;p&gt;Unfortunately, there is no hard data available (at least in open literature) to back up these claims. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One for the claim may be due to the fact that the Tu-144 was designed to fly higher than Concorde as its primary flight path was over land rather than water. Because of this, the L/D ratio of the Tu-144 was higher than that of Concorde (7 vs 8 in Tu-144D). Also, the Tu-144 was bigger and was meant to carry more passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fMd4t.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fMd4t.gif&quot; alt=&quot;3-view comparison of Concorde and Tu-144&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Photo Courtesy: globalsecurity.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://web.archive.org/web/20190513211049/http://www.tupolev.ru/en/aircrafts/tu-144&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev site&lt;/a&gt; offers an interesting explanation for this claim. Basically, they say that despite the engines and other subsystems being inefficient, the Tu-144 performed similar to the Concorde due to superior aerodynamics of the aircraft. The performance of the Tu-144's RD-36 engines was later brought up to that of Concorde's Olympus 593, at least in fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It should be added that the engines were less perfect (by specific parameters the engines of TU-144 a/c were brought close to “Olympus” only in their last modification). All these negative initial data were compensated in the course of development of the project by high aerodynamic cleanness of TU-144 which was achieved by making the design more complicated and by lowering maintainability of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But without any hard data, it is not possible to compare the two aircraft directly.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="20880" LastEditDate="2019-11-15T21:02:11.370" LastActivityDate="2019-11-15T21:02:11.370" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="18964" PostTypeId="2" ParentId="18875" CreationDate="2015-08-17T01:18:19.640" Score="12" Body="&lt;p&gt;Because many copter autopilots are capable of flying a Cat I ILS to 200AGL, and then descending on autopilot into a hover at a pre-determined altitude above the runway. The pilot can then descend down to the runway surface without any forward visibility. The radar altimeter is used to judge distance to the ground. Because of the unique capabilities of helicopters and their autopilots, Cat II and Cat III are superfluous. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-17T01:18:19.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18968" PostTypeId="1" AcceptedAnswerId="18969" CreationDate="2015-08-17T01:31:13.220" Score="2" ViewCount="748" Body="&lt;p&gt;I have wondered this when looking at pictures of the concorde and sometimes it was down and other times it was up and why cant the commercial airplanes have this system.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-17T01:54:24.390" Title="why does the concorde's nose go up and down" Tags="&lt;airliner&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-08-17T06:16:04.813" ContentLicense="CC BY-SA 3.0" />
  <row Id="18969" PostTypeId="2" ParentId="18968" CreationDate="2015-08-17T01:49:41.443" Score="5" Body="&lt;p&gt;When the Concorde is in supersonic flight, the shape of the fuselage has to be very aerodynamic.  On landing, the attitude of the plane is very nose high, so the nose comes down to allow the pilots to see the runway.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-17T01:49:41.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18970" PostTypeId="2" ParentId="18968" CreationDate="2015-08-17T01:54:24.390" Score="3" Body="&lt;p&gt;For any aircraft, the slower you fly, the more the nose is up. For a delta-wing aircraft like Concorde it's even more so, and supersonic flight requires a very slender fuselage. This means during landing and takeoff the nose will block the view forward, and lowering it allows the pilots to see in front.&lt;/p&gt;&#xA;" OwnerUserId="9826" LastActivityDate="2015-08-17T01:54:24.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18972" PostTypeId="2" ParentId="18934" CreationDate="2015-08-17T09:23:03.470" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any other aircraft that have this configuration?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For a similar engine configuration, see the Britten-Norman Trislander, a development of their successful twin &lt;a href=&quot;https://en.wikipedia.org/wiki/Britten-Norman_Islander&quot; rel=&quot;nofollow noreferrer&quot;&gt;Islander&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/q71ZW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/q71ZW.jpg&quot; alt=&quot;Britten-Norman Trislander&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Britten-Norman Trislander (picture &lt;a href=&quot;http://aircraft.wikia.com/wiki/Britten_Norman_Trislander&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, this configuration is unusual. It was driven by the desire to use existing engines on aircraft which grew too large to work with only two engines. Only one other airliner used this layout, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Tristar&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically, the different location of the engines allows to control pitch with thrust input only. However, the slow response of turbofans makes them unsuitable for maneuvering; only trim support is realistically achievable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-18T09:55:14.483" LastActivityDate="2015-08-18T09:55:14.483" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18973" PostTypeId="2" ParentId="18940" CreationDate="2015-08-17T10:42:15.533" Score="17" Body="&lt;p&gt;I use neodymium magnets in my work as a research scientist and I regularly carry them aboard aircraft in packaging.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are not talking fridge magnets here, these are serious high-field permanent magnets. If two of them get properly stuck together they cannot be separated again easily. (The fields are far too strong to be pulled apart by hand and you can't use any metal tools for obvious reasons. One trick is to use a heavy, non-ferrous plastic-coated mallet to smash one off the other at the edge of a table, but even then it's usually half the day wasted.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is that the strength of the force between two such magnets is not intuitively understood by people unfamiliar with them: for example, your typical customs or security inspector. There might be almost no noticeable force between two magnets when they are some distance apart in the packing box but once they get within 5 to 10 centimetres they will suddenly be attracted together and anything in the way (flaps of skin, fingers) will simply be crushed flat under the force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or if nothing slows the magnets down as they come together, the force of the impact can chip the surface of the metallic protective layer, spraying shrapnel and metal fragments everywhere which poses a risk in particular to eyes. (The alloys used in constructing these magnets are extremely brittle.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the magnets get stuck to other large metal objects it can be a pain to separate them. They also induce weak magnetism in metals you normally expect to be non-magnetic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally if they get wiped across anything like a credit card or ID badge that's usually the end of it (not always actually, it's a bit random).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The magnets are not &lt;em&gt;extremely&lt;/em&gt; dangerous, getting small bones broken or metal fragments in the eye is the worse case scenario on my risk assessment, but they are not toys and there is a risk to those untrained in handling them. So anything like this needs to be identified so that they can be treated with care if someone does want to open my luggage to fish around inside it.&lt;/p&gt;&#xA;" OwnerUserId="8565" LastEditorUserId="8565" LastEditDate="2015-08-17T10:53:14.763" LastActivityDate="2015-08-17T10:53:14.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18974" PostTypeId="1" AcceptedAnswerId="18979" CreationDate="2015-08-17T12:28:50.167" Score="3" ViewCount="311" Body="&lt;p&gt;Until Friday I'd flown only with EasyJet and Alitalia. In the last weekend, however, I took two Vueling flights and felt that the way the aircraft manoeuvred during the flight was very different when compared to EasyJet and Alitalia.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Take off seemed more &quot;brutal&quot;, and we seemed to rotate much earlier, where the EasyJet or Alitalia flights will use more of the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;After take off, the airplanes did a lot of maneuvers during climbing. While EasyJet's planes usually do a variation of &quot;turn, long climb, another turn&quot;, the Vuelings' performed a number of turns during climbing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landings, from the point of view of turning, are the same (as it should be). But after touchdown...it seemed to me the pilot maintained a higher rollout and taxi speed for much much more time, so that in both cases after the gear touching ground the plane reached the apron in a matter of seconds - and in both case the planes were yawing a lot when completing their landing roll and taxi, compared to the EasyJet or Alitalia flights.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general the impression was that pilots were piloting in a more &quot;sporty&quot; manner (to use a motoring analogy), if you'll allow me the expression, and other passengers noticed it too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, question is: was it really just an impression? And if not, is there some kind of &quot;direction&quot; the airlines give to their pilots in how handle the plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I'm NOT criticizing in any way the pilots. I know standards are&#xA;pretty high and is not the kind of job one can improvise or do&#xA;careless; I'm not saying or implying that they did pilot badly.&lt;/li&gt;&#xA;&lt;li&gt;Airplanes are pretty the same, I've flown with EJ's A319 and A320,&#xA;both with winglet fences, and the Vueling's one was a brand new A320&#xA;with sharklets.&lt;/li&gt;&#xA;&lt;li&gt;Air conditions were not extreme. In fact, I usually fly&#xA;Easyjet in winter in north Europe (MXP/LGW/CDG) in bad weather&#xA;conditions, while the Vueling flights were during clear days between MXP&#xA;and BCN.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9830" LastEditorUserId="62" LastEditDate="2015-08-17T15:23:56.093" LastActivityDate="2015-08-17T22:14:33.290" Title="Who decides how to &quot;handle&quot; an aircraft, with regards to severity of manoeuvres etc?" Tags="&lt;airlines&gt;&lt;pilot-technique&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="18975" PostTypeId="1" AcceptedAnswerId="18978" CreationDate="2015-08-17T12:57:00.083" Score="2" ViewCount="6550" Body="&lt;p&gt;The FAA utilizes the ICAO definitions for class A-E airspace as controlled and class G as uncontrolled (class F airspace is unused under the FAA). What are the key differences between controlled and uncontrolled airspace in general?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="62" LastEditDate="2015-08-17T14:23:27.483" LastActivityDate="2015-08-18T03:03:31.070" Title="What are the key differences between controlled and uncontrolled airspace under the FAA jurisdiction?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18976" PostTypeId="2" ParentId="18957" CreationDate="2015-08-17T12:57:51.360" Score="5" Body="&lt;p&gt;In terms of role, there is little difference between these two helicopters. Both are attack helicopters used for close combat and anti-armor. They area also capable of carrying almost similar weapons systems and combat commanders can use either of these for the same mission based on their availability(though this will depend on the compatibility of communication equipment)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bell AH-1Z is development (albeit with significant upgrades) of  Bell AH-1, the first attack helicopter of US army. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After AH-1, the US army decided on a dedicated attack helicopter (AH-1 was developed from UH-1 transport), which led to the AH-64 Apache.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AH-64D Block III Longbow is an advanced version of Apache with the Longbow fire control radar. It is under use by a number of countries apart from US Army.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AH-1Z Viper, however, is used only by the USMC.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="39" LastEditDate="2015-08-17T17:53:55.347" LastActivityDate="2015-08-17T17:53:55.347" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18978" PostTypeId="2" ParentId="18975" CreationDate="2015-08-17T13:40:31.420" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot; rel=&quot;nofollow&quot;&gt;This Document&lt;/a&gt; covers all the regs pretty well. But in short the key point on class G (uncontrolled) is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although &lt;strong&gt;ATC has no authority&#xA;  or responsibility to control air traffic&lt;/strong&gt;, pilots should remember&#xA;  there are visual flight rules (VFR) minimums which apply&#xA;  to Class G airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Class G airspace also holds no specific entry requirements (aside from VFR minimums), no specific aircraft equipment (no radio, no transponder etc) and no minimum pilot certificate requirement (but you still need a license (one of a few varieties) you just don't need anything in addition like the instrument rating requirements for class A). On the contrary glass G airspace (uncontrolled) is not a free for all and you are not free to do as you please in some regards. While ATC has no reach into Class G the FAA does and you are still bound by the regulations the FAA puts forth that apply to class G airspace.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise the definition they provide for controlled is  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Controlled airspace is a generic term that &lt;strong&gt;covers the&#xA;  different classifications of airspace and defined dimensions&#xA;  within which air traffic control (ATC) service is provided&lt;/strong&gt;&#xA;  in accordance with the airspace classification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are wondering what the specific purpose of ATC is they define that as well, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The primary purpose of the ATC system is to prevent a&#xA;  collision between aircraft operating in the system and to&#xA;  organize and expedite the flow of traffic.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-17T14:59:53.257" LastActivityDate="2015-08-17T14:59:53.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18979" PostTypeId="2" ParentId="18974" CreationDate="2015-08-17T13:49:50.323" Score="7" Body="&lt;p&gt;Pilot in command, a.k.a. captain, has the last say in how the aircraft will be handled. However most of their decisions are driven by something:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obviously performance of the aircraft. This is affected by weight (both cargo and fuel; aircraft only take the amount of fuel they need for the route they are flying and it makes a big difference) and weather (mainly temperature and head-wind).&lt;/li&gt;&#xA;&lt;li&gt;Standard operating procedures (SOP). Certain operations can indeed be done in more than one way and each airline may indeed make slightly different choices. These are reflected in the recurrent pilot training.&lt;/li&gt;&#xA;&lt;li&gt;Route flown. Airline flights are carried out under instrument flight rules, so the route is assigned by the air traffic control.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Take off seemed more &quot;brutal&quot;, and from a position slightly more at the beginning of the runways.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is some freedom in choosing the take-off setting and standard operating procedure of different airlines may make different choices. Usually if the runway is long enough the engines are not set to full thrust, but so called “flex” thrust that is calculated sufficient for the take-off to limit wear of the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What thrust and flap setting are possible is determined by weight, runway length, wind and temperature, but within the possible range, different airline may have different preference in their SOP (higher power or less flaps for faster climb v.s. lower power for less engine wear and more flaps for lower gear wear).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noticeable difference might be in using “rolling take-off” where power is added immediately after turning on the runway without stopping there first. Whether it is possible depends on ATC, but some airlines seem to never do it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After take off, the airplanes did a lot of maneuvers during climbing. While EasyJet's planes usually do a variation of &quot;turn, long climb, another turn&quot;, the Vuelings' did &quot;a lot&quot; of turns during climbing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on the departure route assigned by the controller. Note that even if flying the same route, the departure route could be different if different runway was used or if different routing was selected due to congestion (European airspace gets &lt;em&gt;very&lt;/em&gt; busy at times and then the plane may wait or use different route).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Landings, from the point of view of turning, are the same (as it should be).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not necessarily. Arrival routes may differ similarly to how departure routes do. In fact even more so, because on arrival the aircraft are often vectored, that is get ad-hoc headings assigned by controller instead of flying standard route depicted on the chart, to achieve appropriate separation. On take-off the aircraft simply wait on the ground until the previous aircraft is far enough so it's not needed often.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But after touchdown...it seemed to me the pilot kept an higher speed for much much more time, so that in both cases after the gear touching ground the plane reached the apron in a matter of seconds&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again there can be differences in SOP regarding preferred auto-brake setting, but usually every pilot will want to vacate the runway as soon as possible, so it seems more like difference in what exits were available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It &lt;em&gt;might&lt;/em&gt; have also been difference in the aircraft. There was some talk about Airbus implementing “brake to vacate”, where the computer handles the brakes so the aircraft slows down just before the next suitable turn-off, on the new A320, but I found no reference whether they already did.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;and in both case the planes were swinging a lot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The vertical tail acts like a weather-vane and the thrust reversers reduce lateral stability, so the aircraft always needs some directional corrections during landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the air the aircraft turns by banking, so you don't feel any lateral movement. But on the ground it can't and due to the speed you feel even very slight turns.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-17T13:49:50.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18980" PostTypeId="1" CreationDate="2015-08-17T13:52:23.350" Score="8" ViewCount="767" Body="&lt;p&gt;Several years ago we were issued an airport designation number by the FAA. The information was lost when my father died. How do I find out what our designation number is?&lt;/p&gt;&#xA;" OwnerUserId="9833" LastEditorUserId="19" LastEditDate="2016-07-08T09:54:38.767" LastActivityDate="2016-07-08T09:54:38.767" Title="How can I find our FAA airport designation number?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="18981" PostTypeId="2" ParentId="18980" CreationDate="2015-08-17T14:21:00.953" Score="13" Body="&lt;p&gt;What you're looking for is the FAA &lt;a href=&quot;https://en.wikipedia.org/wiki/Airport/Facility_Directory&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport/Facility Directory (A/FD)&lt;/a&gt;. You can search it on the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/advanced/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA A/FD Advanced search page&lt;/a&gt;. If your runway is registered as an airport with the FAA, its airport identifier will be in the A/FD. It will also include the runway numbers (there will be one for each end of the runway,) as well as other information about the runway (surface type, exact heading, altitude, etc.) See &lt;a href=&quot;https://aviation.stackexchange.com/q/65/755&quot;&gt;How are runways numbered?&lt;/a&gt; for more information on runway numbers. Another website available for searching A/FD information is &lt;a href=&quot;http://www.airnav.com/airports/&quot; rel=&quot;nofollow noreferrer&quot;&gt;airnav.com&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to find information on the airport is to look at a &lt;a href=&quot;https://en.wikipedia.org/wiki/Sectional_chart&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sectional Chart&lt;/a&gt;. For most private airports, an 'R' with a circle around it will appear where your runway is located and it will have the name of the airport beside it. You can then use that name to look it up in the A/FD. &lt;a href=&quot;https://skyvector.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skyvector.com&lt;/a&gt; is an easy way to look at sectional charts. It works a lot like Google Maps, except that it shows you the FAA sectional chart for your area rather than a normal map. You can just zoom in on your area to find the airport marker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your airport will look something like the one that I've circled in red on this sectional chart image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4Zp1G.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4Zp1G.png&quot; alt=&quot;Sectional chart showing private airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your runway has a hard surface (i.e. it's paved with asphalt or concrete) and is more than 1,500 feet long, it might look like the airport circled in the picture below rather than having the circled 'R'. In this picture, the purple circle indicates the airport and the white line within the circle indicates the location and orientation of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NUDOI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NUDOI.png&quot; alt=&quot;Sectional chart showing private airport with paved runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-17T15:29:44.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18982" PostTypeId="1" AcceptedAnswerId="18984" CreationDate="2015-08-17T14:22:19.597" Score="3" ViewCount="398" Body="&lt;p&gt;The Wikipedia page for the &lt;a href=&quot;https://en.wikipedia.org/wiki/USS_Wolverine_(IX-64)&quot; rel=&quot;nofollow&quot;&gt;USS Wolverine&lt;/a&gt; says that the low flight deck of that carrier is disadvantageous for warplane landing, but it was 70 years ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming other things (including displacement, length, width and draft of carriers, flight deck length, width and texture.), is it easier to land the latest planes on an aircraft carrier with a high flight deck? &lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="62" LastEditDate="2015-08-17T14:27:09.907" LastActivityDate="2015-08-17T14:49:04.777" Title="Is it easier to land planes on an aircraft carrier with a high flight deck?" Tags="&lt;landing&gt;&lt;aircraft-carrier&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18983" PostTypeId="1" AcceptedAnswerId="18985" CreationDate="2015-08-17T14:24:48.520" Score="3" ViewCount="298" Body="&lt;p&gt;This question is asked in the context of small certified GA aircraft in the US. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TIS-B traffic that is displayed on board is a subset of all the TIS-B traffic in the area. It's often described as a hockey puck surrounding your aircraft where other traffic that is outside the puck is not displayed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is whether the algorithm that filters what does or doesn't get displayed resides on the onboard box or the ground station. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the ground station (which knows your position because of your ADS-B out) send a custom set of traffic suited for your hockey puck? OR... &lt;/li&gt;&#xA;&lt;li&gt;Does the ground station send out all traffic it is aware of and your on-board box filter only the ones in your hockey puck and send them onto your display? OR... &lt;/li&gt;&#xA;&lt;li&gt;Something else?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="340" LastEditorUserId="5517" LastEditDate="2015-08-17T17:30:23.513" LastActivityDate="2015-08-17T20:12:07.960" Title="Is the TIS-B traffic filter on board or on the ground?" Tags="&lt;ads-b&gt;&lt;tis-b&gt;&lt;nextgen&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18984" PostTypeId="2" ParentId="18982" CreationDate="2015-08-17T14:40:50.820" Score="7" Body="&lt;h2&gt;Then&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It used to matter, because aircraft would sometimes approach the carrier at a lower altitude than even the flight deck before pulling up briefly and practically stalling onto the deck, allowing for a lower speed landing. Similarly, the higher flight deck would give an extra couple of metres of acceleration if over-shooting the flight deck and having to go around. As such a high-decked carrier gave a little more margin for error.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Now&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It makes virtually no difference - modern aircraft approach at the same angle and airspeed regardless of the height of the deck (within reason). They also perform approaches significantly more accurately. If anything, the higher deck could be considered a (very) &lt;strong&gt;slight&lt;/strong&gt; disadvantage, as it may display a higher rolling moment than a low deck carrier. This is unlikely to cause any issues, however.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-08-17T14:49:04.777" LastActivityDate="2015-08-17T14:49:04.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18985" PostTypeId="2" ParentId="18983" CreationDate="2015-08-17T14:42:17.720" Score="4" Body="&lt;p&gt;TIS-B is part of the ADS-B system that will be required in class B and C airspace come 2020. The processing of traffic relevant to your aircraft is done on the ground to keep the airwaves &quot;clean&quot; as it would require transmission of much more data to show all aircraft and then have your local device filter it. In order for you to take advantage of your own &quot;hockey puck&quot;, you first need to have installed in your aircraft the appropriate avionics, namely a GPS with WAAS and an ADS-B out or Mode S transponder. Your transponder will broadcast your location and altitude, then the ground station will process which traffic is relevant to you without the 3D boundaries of the &quot;hockey puck&quot; surrounding your aircraft, then it will broadcast that response out to the air. The key is that not only your aircraft can pick up the response - any aircraft with an operable ADS-B In system can read it and thus display traffic/give traffic alerts even if you don't have an ADS-B out. The key though is that without an ADS-B out the traffic information is not customized for you so critical information/traffic may be missing (what is transmitted is might not be in YOUR hockey puck).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; It is also possible for you to pick up signals directly from other ADS-B out equipped aircraft in your proximity without an ADS-B ground station to relay that information and they will display directly on your ADS-B in equipped system.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2015-08-17T20:12:07.960" LastActivityDate="2015-08-17T20:12:07.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18988" PostTypeId="1" AcceptedAnswerId="18990" CreationDate="2015-08-17T15:52:24.380" Score="16" ViewCount="2446" Body="&lt;p&gt;For all runways I've known or seen, they're numbered on both sides, with the number on the opposite direction differ by 18.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there runways that are numbered only on one side? I.e. due to certain constrains, the runway can only be used in one direction and never the other.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: I'm looking for runways where the aircraft is always pointing at the &lt;em&gt;same direction&lt;/em&gt;. E.g. only runway 9 is available, you can never use runway 27 for whatever reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A runway that is blocked on one end will still have two numbers, since you'd land at one direction and takeoff the other.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-08-18T01:07:44.370" LastActivityDate="2019-04-28T00:39:27.300" Title="Are there runways that are numbered only on one side?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="18989" PostTypeId="2" ParentId="18988" CreationDate="2015-08-17T16:04:08.020" Score="2" Body="&lt;p&gt;A mountain can get in the way for example at Lukla airport &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The topography of the place makes any go-around impossible. At the&#xA;  south, the runway is the end of an angled drop of about 2000 feet.&#xA;  This cliff is fenced off as a precautionary measure. At the northern&#xA;  end of the runway there is a huge mountain terrain. It leaves no room&#xA;  for error. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://travel-safety.knoji.com/interesting-facts-on-lukla-airport-the-most-dangerous-airport-in-the-world/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes land on runway 6 and take off on runway 24.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Yx9m0.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt; most information copied from &lt;a href=&quot;https://aviation.stackexchange.com/a/8806/609&quot;&gt;this answer&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-17T16:04:08.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18990" PostTypeId="2" ParentId="18988" CreationDate="2015-08-17T16:09:57.920" Score="26" Body="&lt;p&gt;Yes, there are runways numbered on only one side. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the third runway in the Frankfurt Airport (&lt;strong&gt;18&lt;/strong&gt;, Runway west) is used only for takeoffs (to the south) and not for landings. Hence only number &lt;strong&gt;18&lt;/strong&gt; is used. The other runways are used for both takeoffs and landings and are numbered 07C/25C, 07R/25L and 07L/25R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RFBya.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RFBya.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;Thomas Römer/OpenStreetMap data [&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/2.0&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 2.0&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Frankfurt-Main_Airport_Map_EN.png&quot; rel=&quot;noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This restriction is due to the fact that it will interfere with the traffic in other runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0TXwQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0TXwQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;Number 36 is not painted.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-04-28T00:39:27.300" LastActivityDate="2019-04-28T00:39:27.300" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="18992" PostTypeId="1" AcceptedAnswerId="18993" CreationDate="2015-08-17T16:20:03.873" Score="4" ViewCount="873" Body="&lt;p&gt;On &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_32&quot; rel=&quot;nofollow&quot;&gt;Qantas Flight 32&lt;/a&gt; there was... &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...an undetected fire in the left inner wing fuel tank that eventually&#xA;  &lt;strong&gt;self-extinguished&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does a fire in a nearly full fuel tank self-extinguish?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="62" LastEditDate="2015-08-17T16:44:11.223" LastActivityDate="2015-08-17T16:54:30.210" Title="How does a fuel tank fire self-extinguish in an A380?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="18993" PostTypeId="2" ParentId="18992" CreationDate="2015-08-17T16:37:07.753" Score="7" Body="&lt;p&gt;The &lt;a href=&quot;http://www.atsb.gov.au/media/4173625/ao-2010-089_final.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Australian Transportation Safety Board's Final Report&lt;/a&gt; gives a couple of possible reasons that the reaction was not sustained in Appendix D on page 257:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The flash fire initially consumed the oxygen inside the tank; reducing the oxygen concentration level to below the threshold required for sustained combustion of Jet A-1.  &lt;/li&gt;&#xA;  &lt;li&gt;The general temperature rise associated with the initial combustion was low and insufficient to increase the temperature of the fuel inside the tank to at least the lower flammability limit of Jet A-1. Quenching of the flame by the cool fuel tank walls (evident from the sooting) and the entry of cooling air through the tank perforations may have promoted this.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that Jet-A requires quite a bit of activation energy to vaporize and burn. If the burning of what fuel did burn didn't produce enough energy to provide activation energy for the surrounding fuel, the fire would not be sustained. The fire was likely very brief as the turbine disc fragment passed through the tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I've heard (I haven't tried this myself,) you can drop a lit match in a bucket of Jet-A and it won't ignite. Using fuel that doesn't easily burst into flames in a vehicle designed to carry tens of thousands of gallons of fuel at several hundred miles per hour is desirable and intentional for obvious reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate just how hard it is to burn Jet-A, the fuel tanks in Asiana 214 &lt;em&gt;never ignited&lt;/em&gt;. The entire fuselage was burned out, but the fuel tanks never burned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wk3gw.jpg&quot; alt=&quot;Remnants of Asiana 214&amp;#39;s hull&quot;&gt;&lt;br&gt;&#xA;Remnants of Asiana 214's hull &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:NTSBAsiana214Fuselage2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-08-17T16:54:30.210" LastActivityDate="2015-08-17T16:54:30.210" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18994" PostTypeId="1" AcceptedAnswerId="18999" CreationDate="2015-08-17T16:43:34.213" Score="16" ViewCount="8294" Body="&lt;p&gt;I've never understood the purpose of yawing, i.e., rotating around the vertical axis by activating the rudder. Provided that airplanes have ailerons that allow banking (used for turning), why do they actually need to yaw? Furthermore, I've read that yawing induces an undesired banking because of the different lifts generated by each wing, due to the fact that one wing &quot;feels&quot; a higher airspeed than the other (a similar effect as a car's wheel spinning faster than the other during a turn). So, if yawing is so &quot;useless&quot; or bothering, why do airplanes have rudders? Moreover, could an airplane takeoff, fly and land without rudder?&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="247" LastEditDate="2015-08-17T18:32:18.807" LastActivityDate="2018-11-23T12:21:56.340" Title="What's the purpose of yawing?" Tags="&lt;flight-controls&gt;&lt;rudder&gt;" AnswerCount="6" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18995" PostTypeId="2" ParentId="18994" CreationDate="2015-08-17T17:50:26.317" Score="16" Body="&lt;p&gt;The purpose of yawing is, as you note, to provide a way to rotate the airplane around a vertical axis.  Ailerons can roll the airplane around a longitudinal axis and produce a slipping turn, and turning with the rudder alone produces a skidding turn, but proper turning is a combination of both aileron and rudder inputs and produces a &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight&quot;&gt;coordinated turn&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turning with aileron alone creates &lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw&quot;&gt;adverse yaw&lt;/a&gt; when the rising wing provides more lift and more drag than the lowering wing, causing a yawing moment away from the intended direction of turning.  Additionally, if you want to maintain effective gravity downward in your reference frame, you need a yaw moment and rudder is what provides that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many other situations where rudder is essential to flight&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Correcting for &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot;&gt;p-factor&lt;/a&gt; turning tendencies&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Crosswind_landing#Sideslip&quot;&gt;Takeoff and landing in crosswinds&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/PARE_(aviation)&quot;&gt;Spin recovery&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Stall_(fluid_mechanics)#Symptoms_of_an_approaching_stall&quot;&gt;Controllability in stalls&lt;/a&gt; to prevent spin entry&lt;/li&gt;&#xA;&lt;li&gt;Engine failure in multi-engine airplanes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If rudder were useless, we wouldn't have them.  There are airplanes without rudder &lt;em&gt;pedals&lt;/em&gt;, e.g. the &lt;a href=&quot;https://en.wikipedia.org/wiki/ERCO_Ercoupe&quot;&gt;ercoupe&lt;/a&gt; but this plane still has rudders that act in accordance with the ailerons through turning the yoke to provide the necessary forces for coordinated turns. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-08-17T17:56:44.613" LastActivityDate="2015-08-17T17:56:44.613" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="18996" PostTypeId="1" CreationDate="2015-08-17T18:13:00.033" Score="2" ViewCount="708" Body="&lt;p&gt;In current missile, what is the guidance law used at terminal phase in homing missile guidance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;eg: Proportional navigation, Augumented PN, Optimal Guidance Law, etc&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At what distance the terminal phase guidance engage for Air Interceptor Missile(AIM) { eg: sidewinder, Derby, etc }. This is for active seeker(radar). And what is the terminal phase guidance used for active (radar) seeker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;what are information get from seeker to guidance system at terminal phase using active seeker(radar), other than Line_of_Sight(LOS) and Relative range(R) between missile and target.&lt;/p&gt;&#xA;" OwnerUserId="9834" LastEditorUserId="9834" LastEditDate="2015-08-20T05:28:58.380" LastActivityDate="2015-08-20T05:28:58.380" Title="In current missile, what is the guidance law used at terminal phase in homing missile guidance?" Tags="&lt;missiles&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-08-21T07:01:34.330" ContentLicense="CC BY-SA 3.0" />
  <row Id="18997" PostTypeId="2" ParentId="18983" CreationDate="2015-08-17T18:51:00.800" Score="0" Body="&lt;p&gt;TIS-B transmissions are broadcast (the -B) which mean they are not addressed to individual aircraft. The TIS-B transmitter will not select traffic of interest for your specific aircraft, as it provides the data simultaneously to many TIS-B receiving aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the display system in the aircraft only shows a 'hockey puck' of TIS-B traffic, then some filtering must be done in the ADS-B / TIS-B receiver on board of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information contained in TIS-B transmissions covers a wide area. That is usually the area that the transmissions can be received in and then some buffer. To achieve this, some geographical filtering is done in the TIS-B server which provides data to the TIS-B transmitters. This is needed to protect the radio spectrum from unnecessary transmissions; it is useless to report the position of an aircraft that is a couple of states away. To make efficient use of the radio frequency, TIS-B transmitters may use multiple directional antennas,each broadcasting only the traffic that is relevant to its covered airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summarizing:  there is filtering done on both the transmitter side and the receiver side, but the selection of which traffic is relevant to your aircraft is done on board. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-08-17T18:56:57.537" LastActivityDate="2015-08-17T18:56:57.537" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="18998" PostTypeId="2" ParentId="18996" CreationDate="2015-08-17T18:55:08.277" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.jhuapl.edu/techdigest/td/td2901/palumbo_homing.pdf&quot; rel=&quot;nofollow&quot;&gt;this easy to read brief introduction:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;Optimal Homing Guidance Laws&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Other Optimal Homing Guidance Laws, many modern guidance laws require&#xA;  an estimate of time-to-go (tgo), which is the time it will take the&#xA;  missile to intercept the target or to arrive at the closest point of&#xA;  approach (CPA). The tgo estimate also is a critical quantity for&#xA;  missiles that carry a warhead that must detonate when the missile is&#xA;  close to the target.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-08-17T18:55:08.277" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="18999" PostTypeId="2" ParentId="18994" CreationDate="2015-08-17T19:08:19.820" Score="37" Body="&lt;p&gt;From a totally practical standpoint, let's say you're in a small tricycle gear aircraft with a freely castoring nose wheel (or a tail dragger) and you're starting your takeoff roll in a calm wind. When you bring the power up, the aircraft is going to want to turn left (&lt;a href=&quot;http://wiki.flightgear.org/Understanding_Propeller_Torque_and_P-Factor&quot; rel=&quot;noreferrer&quot;&gt;why is another question&lt;/a&gt;), in other words to yaw about its vertical axis in a counter-clockwise direction, and head for the grass off the left side of the runway. You counteract that adverse yaw by using right rudder to keep the airplane straight. Initially you might have to use some right brake as well until there's sufficient air moving past the rudder. If you had a steerable nose gear, you wouldn't need the right brake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You reach flying speed, apply up elevator, and lift off. As the airplane rotates about its lateral axis, there'll be some additional adverse yaw as a result of that rotation (again another question). Even if you had a steerable nose gear, that would now be useless as the nose gear is no longer on the ground. Your means of continuing to fly straight ahead is to counter the adverse yaw with rudder, and you would continue to use right rudder as you climb out. If you don't, you'll start turning left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You reach the altitude you want, level off, and trim for level flight straight ahead. Then you decide you want to turn left. You start the turn briskly with left aileron, but you forgot to use any rudder. If you were looking at the ball on the bottom of the turn and bank indicator, you would see it shoot left. If you had used left rudder while initiating the turn, that wouldn't have happened. You would have started a coordinated turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you're coming back to the airport, and there's a crosswind from the left. You decide you want to counter that crosswind by slipping into it. In other words, you want the airplane to travel sideways at a speed that matches the crosswind while still having your nose pointing straight down the runway. So, you lower the left wing and to keep the airplane from turning, you use right rudder to keep the airplane aligned with the runway. You match the crosswind by adding or decreasing your bank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other uses of rudder, and especially in aerobatics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I once flew a few loads of skydivers. The jumpmaster sat behind me, and to help him in positioning for the drop zone, he wanted flat turns. In other words, he wanted the airplane turned while keeping the wings level. So, if he wanted a left turn, that meant left rudder and right aileron. Uncomfortable from a pilot's standpoint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, back in the 1960s when I was working on my instrument rating, I had an instructor who taught that the best way to track a localizer in close was to use rudder only for small corrections. Personally, I don't like that method, but it's one way of doing things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A useful thing, the rudder. You need to be able to directly control movement about all three aircraft axes.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="9853" LastEditDate="2015-08-19T00:38:15.397" LastActivityDate="2015-08-19T00:38:15.397" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19000" PostTypeId="2" ParentId="18930" CreationDate="2015-08-17T19:43:27.890" Score="3" Body="&lt;p&gt;The runway edge stripe does not define the runway boundary.  The runway boundary line defines the runway boundary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Runway Boundary Line:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZCC8q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZCC8q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all airports right of way rules are covered in &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;14 CFR 91.113 &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) &lt;em&gt;General.&lt;/em&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When weather conditions permit, regardless of whether an&#xA;  operation is conducted under instrument flight rules or visual flight&#xA;  rules, vigilance shall be maintained by each person operating an&#xA;  aircraft so as to see and avoid other aircraft. When a rule of this&#xA;  section gives another aircraft the right-of-way, the pilot shall give&#xA;  way to that aircraft and may not pass over, under, or ahead of it&#xA;  unless well clear.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) &lt;em&gt;Landing.&lt;/em&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Aircraft, while on final approach to land or while landing,&#xA;  have the right-of-way over other aircraft in flight or operating on&#xA;  the surface, except that they shall not take advantage of this rule to&#xA;  force an aircraft off the runway surface which has already landed and&#xA;  is attempting to make way for an aircraft on final approach. When two&#xA;  or more aircraft are approaching an airport for the purpose of&#xA;  landing, the aircraft at the lower altitude has the right-of-way, but&#xA;  it shall not take advantage of this rule to cut in front of another&#xA;  which is on final approach to land or to overtake that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For controlled airports with clearance from the tower multiple aircraft may back-taxi (usually two at a time) for departure.  The first aircraft will line up.  The second aircraft will wait in the turnaround area for the first aircraft to takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no rule explicitly prohibiting multiple aircraft occupying the same runway.  However the above regulation does provide guidance in answering this question.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Here are some uncontrolled airport scenarios...&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario 1:  Aircraft A is in the turn around area (not in a holding bay) preparing to takeoff.  Aircraft B is on final to land.  Aircraft B has the right of way.  Aircraft A is in violation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario 2:  Aircrafts A and B will depart on a group flight together (they have coordinated with each other prior to operating).  They both taxi to the end of the runway and line up for departure.  Both aircraft could take off in sequence with each other, or one aircraft could wait in the turnaround area while the other takes off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario 3:  Aircraft A is in a holding bay (explained in &lt;a href=&quot;https://aviation.stackexchange.com/questions/18930/in-the-u-s-is-it-ever-legal-for-an-aircraft-to-occupy-the-runway-turnaround-ar/19002#19002&quot;&gt;fooot's answer&lt;/a&gt;).  Aircraft B is on final to land.  Aircraft B has the right of way.  Aircraft A is outside the runway boundary and not in violation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario 4:  Aircraft A is in a turnaround area.  Aircraft B is on take off roll.  Aircraft B has the right of way.  Aircraft A must give way to Aircraft B until there is sufficient room to safely pass or Aircraft B is well clear.&lt;/p&gt;&#xA;" OwnerUserId="651" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-08-18T17:06:11.473" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19001" PostTypeId="2" ParentId="18994" CreationDate="2015-08-17T19:57:58.550" Score="6" Body="&lt;p&gt;A turn performed with just the ailerons and elevator will not be &quot;coordinated&quot;. This is to say, the apparent G force will not go straight &quot;down&quot; through the aircraft's floor, which is desirable for various reasons. Among them is passenger comfort (being pulled down is less unpleasant than being pulled sideways), but there are &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight#Advantages&quot;&gt;other advantages too&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to making coordinated turns, the rudder is useful to correct yaw induced by gusts of wind, to set up and maintain a wing down attitude in a sideslip crosswind landing, to &lt;a href=&quot;https://en.wikipedia.org/wiki/Slip_%28aerodynamics%29#Forward-slip&quot;&gt;quickly lose altitude&lt;/a&gt; without picking up lots of speed (somewhat notably used by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider#Landing_at_Gimli&quot;&gt;Gimli Glider&lt;/a&gt;), and for various aerobatic maneuvers.&lt;/p&gt;&#xA;" OwnerUserId="2194" LastEditorUserId="2194" LastEditDate="2015-08-17T20:03:08.370" LastActivityDate="2015-08-17T20:03:08.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19002" PostTypeId="2" ParentId="18930" CreationDate="2015-08-17T19:59:35.003" Score="9" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/19000/1696&quot;&gt;Jim's answer&lt;/a&gt; is accurate. Unless there is a proper boundary between the turnaround and the runway, an aircraft should not be there while other aircraft are landing or taking off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the FAA's &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5300-13A-chg1-interactive.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC about airport design&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Obstacle Free Zone (OFZ). The OFZ is the three-dimensional airspace along the runway and extended runway centerline that is required to be clear of obstacles for protection for aircraft landing or taking off from the runway and for missed approaches.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The dimensions of the zone are different depending on the aircraft size and approach minimums. Specifically the runway OFZ has widths from 120 to 400 feet. This is the zone typically protected by the hold lines (&lt;a href=&quot;https://aviation.stackexchange.com/a/19000/1696&quot;&gt;pictured in Jim's answer&lt;/a&gt;), which are typically placed to provide adequate separation for the worst anticipated case at that airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the edge markings, they should be parallel to each other and not follow the edge of a turnaround pad. From the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5340_1l.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC on airport markings&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When a taxiway connects to a runway or the runway has turn pads or turnarounds, the runway edge marking remains continuous between the runway and these adjoining infrastructures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the turnaround pad is designed to be occupied while the runway is in use, this is referred to as a holding bay. A proper holding bay would look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lG9Sx.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lG9Sx.png&quot; alt=&quot;Holding bay illustration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This illustration comes from the airport design AC. Notice that the FAA considers this poor, because it provides no guidance such as taxiway center lines for pilots to follow.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-17T19:59:35.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19003" PostTypeId="2" ParentId="3581" CreationDate="2015-08-17T20:49:43.527" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.cbsnews.com/news/commercial-jet-and-drone-had-close-call-over-florida-faa-says/&quot; rel=&quot;nofollow&quot; title=&quot;This one&quot;&gt;This one&lt;/a&gt; in Tallahassee with a regional jet got a lot of attention when it happened but there are many more. The FAA keeps a database, and I expect we'll see about an actual collision with a Part 121 aircraft soon enough as the number of airborne UAVs is increasing rapidly.&lt;/p&gt;&#xA;" OwnerUserId="1847" LastActivityDate="2015-08-17T20:49:43.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19004" PostTypeId="2" ParentId="18996" CreationDate="2015-08-17T21:48:32.407" Score="3" Body="&lt;p&gt;Normally the terminal phase of trajectory will be computed by some specialized algorithm which is specific to the missile, particularly to the type of sensor and processor used as well as the nature of the propulsion and maneuverability characteristics of the vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this is that during the terminal phase only a few measurements are possible. For example, let's imagine the signal train of the weapon's seeker has a 15 millisecond sensor loop time, a 50 millisecond control loop, and the vehicle is traveling 1500 feet per second. In that case you make one measurement every 22 feet and one control change every 75 feet. So, if the weapon is 200 feet away from the target it will get to make only 2 control changes before intercept based on about 8 measurements total. Depending on the type of measurement, there will be a highly specialized algorithm which is designed to optimize the chance of a kill given the limited information available.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-17T21:48:32.407" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19005" PostTypeId="2" ParentId="18994" CreationDate="2015-08-17T22:01:04.357" Score="-2" Body="&lt;p&gt;There are two main reasons: control on the ground and efficiency in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aircraft is rolling on the ground, the only way to control its direction is with the rudder. When a pilot both takes off and lands an aircraft they use the rudder to steer. If the aircraft had no rudder, it would likely roll off the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight, the rudder is used to keep the fuselage parallel to the line of travel. For example, if the pilot makes a turn without using the rudder air will hit the side of the aircraft and the drag on the plane will be significantly higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another cause of inefficiency in propeller aircraft is what is known as &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow&quot;&gt;P-factor&lt;/a&gt;. This is a yawing of the aircraft due to asymmetrical force in the propeller causing drag. The pilot must hold down the rudder constantly to prevent this. It can become quite tiring to do so in long flights.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-17T22:01:04.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19006" PostTypeId="2" ParentId="18974" CreationDate="2015-08-17T22:14:33.290" Score="1" Body="&lt;p&gt;Whoever is pilot in command decides how to fly the plane. Commercial airlines have professional instructors who examine the more junior pilots and give them guidance on how to fly smoothly. In general, pilots with passengers try to avoid flying in a way that would make them uncomfortable. However, it is completely up to the pilot at the end of the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a particular pilot or crew generate a lot of passenger complaints, the airline might warn the pilots or even fire them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that different flights will have very different maneovering requirements depending on the flight path. So, even if you take the exact same flight multiple times, factors like wind direction and traffic can result in much different amounts of maneovering during ascent and landing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-17T22:14:33.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19007" PostTypeId="1" AcceptedAnswerId="19013" CreationDate="2015-08-17T22:29:51.740" Score="5" ViewCount="5734" Body="&lt;p&gt;I've noticed that there is some variation in the location of the wing on airliners: The Boeing 737 has its wing mounted near the midpoint of the fuselage:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PO5ns.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PO5ns.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;while other aircraft like the CRJ or the Airbus concept plane shown below have the wing mounted further aft.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/qkAOi.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qkAOi.png&quot; alt=&quot;CRJ&quot;&gt;&lt;/a&gt;&lt;a href=&quot;https://i.stack.imgur.com/cg4VB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cg4VB.png&quot; alt=&quot;Airbus Concept&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages or disadvantages to these wing locations, and why might a designer pick one over the other.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="64" LastEditDate="2015-08-18T05:35:45.367" LastActivityDate="2018-11-01T17:30:30.453" Title="What are the advantages and disadvantages of have the wing positioned further aft on an airplane?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;wing&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19008" PostTypeId="1" AcceptedAnswerId="19024" CreationDate="2015-08-17T22:43:00.373" Score="6" ViewCount="424" Body="&lt;p&gt;If I fitted an &lt;a href=&quot;https://www.faa.gov/uas/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Unmanned Aircraft System (UAS)&lt;/a&gt; with an operating Mode C transponder and maintained two-way radio contact with ATC, could my UAS be cleared into class B airspace in the USA?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Inspired by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/18849/what-legal-actions-would-be-taken-against-a-drone-pilot-if-they-flew-a-drone-int&quot;&gt;What legal actions would be taken against a drone pilot if they flew a drone into class B airspace?&lt;/a&gt;&#xA;)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-08-19T12:08:19.493" Title="Can an appropriately-fitted UAS (of any size category) be flown in Class B airspace?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;&lt;class-b-airspace&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19009" PostTypeId="1" AcceptedAnswerId="19014" CreationDate="2015-08-17T22:50:07.927" Score="14" ViewCount="2572" Body="&lt;p&gt;At the non-towered airport I fly at, pilots when clear of the runway always say &quot;X Traffic, Skyhawk N123 clear of the active.&quot; Why not say the runway number? At a one-runway airport, I understand that this could be redundant, but wouldn't it be better to get in the habit of saying the runway number so that--should there be more than one runway--it wouldn't be an issue? &lt;/p&gt;&#xA;" OwnerUserId="9418" LastEditorUserId="9418" LastEditDate="2015-08-17T23:49:04.533" LastActivityDate="2015-08-18T05:33:05.920" Title="Why do pilots say &quot;clear of the active&quot; at non-towered airports?" Tags="&lt;phraseology&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19011" PostTypeId="1" AcceptedAnswerId="19012" CreationDate="2015-08-17T23:26:36.727" Score="7" ViewCount="23842" Body="&lt;p&gt;Maybe guys could provide me with a picture I originally thought the anti-shock pads were fuel tanks, but somebody recently told me that they are stored in the wing, so where are they stored at. The aircraft I refer to are like the (b737), (b747-8)(b787)(a-350)&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="7532" LastEditDate="2017-12-13T01:15:54.803" LastActivityDate="2017-12-13T01:15:54.803" Title="Where is the fuel stored on an aircraft’s wing?" Tags="&lt;airliner&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19012" PostTypeId="2" ParentId="19011" CreationDate="2015-08-17T23:32:17.307" Score="12" Body="&lt;p&gt;This depends on the aircraft. In many cases there is a tank inside the wing. In some cases it can be stored in a soft bladder in the wing and in other cases the wing its self is the tank. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an in wing tank &#xA;&lt;a href=&quot;https://i.stack.imgur.com/KFBNA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KFBNA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some in wing fuel bladders. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/st38W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/st38W.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mooney was known for having integrated fuel tanks in their wing designs. &lt;a href=&quot;http://s1284.photobucket.com/user/MartiniMan1/media/ResealwithTopCoat6_zps18e9b3c4.jpg.html&quot; rel=&quot;noreferrer&quot;&gt;Here are some pictures&lt;/a&gt; of the tanks being resealed. They are notorious for needing a reseal every now and again but they do save in weight. Modern composite structures often don't lend to this design as jet fuel or avgas and composites don't really mix.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vqj7A.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vqj7A.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice cutaway of the A330 to show where the tanks are. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/3dKuE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3dKuE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that you can generally pump fuel between the tanks however care must be taken when this is done because it can greatly effect the CG. &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot; rel=&quot;noreferrer&quot;&gt;This podcast&lt;/a&gt; has some really interesting information on how complex it was to manage the fuel weight on the Concorde and how it needed to be pumped around the tanks during various phases of the flight just to keep the plane stable.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-18T01:57:44.490" LastActivityDate="2015-08-18T01:57:44.490" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19013" PostTypeId="2" ParentId="19007" CreationDate="2015-08-17T23:38:59.310" Score="4" Body="&lt;p&gt;The wings produce not only lift, but also a pitching moment. Usually, it is destabilizing in the sense that it causes nose up of the aircraft as the aerodynamic center is in front of the cg (which causes further nose up and so on). This moment is then counteracted by the tail.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CffyN.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CffyN.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Pic: adg.stanford.edu.&lt;/p&gt;&#xA;&lt;p&gt;As we move the wing to the aft, the stability increases and once the wing is behind the c.g, the aircraft becomes stable.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3gDrs.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3gDrs.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Pic: adg.stanford.edu&lt;/p&gt;&#xA;&lt;p&gt;Although this is stable, the configuration causes a nose down moment when lift is increased. However, we also want that the aircraft be trimmed (i.e. at moment equilibrium at the desired c.g).&lt;/p&gt;&#xA;&lt;p&gt;With single wing, this is not easy with a reasonable static margin. Another thing is that as the wing is moved aft, the c.g also shifts aft.&lt;/p&gt;&#xA;&lt;p&gt;It is possible to have wings in the rear. In that case, it becomes necessary to add a canard for controlling at he aircraft. A good example would be the Gyroflung Speed Canard.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E60pd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E60pd.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As already noted, the aircraft has a canard for control.&lt;/p&gt;&#xA;&lt;p&gt;The location of the engine and wing are related. As the engines are moved aft, the c.g. shifts in that direction and the wing is moved aft to reduce the tail surface needed.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-17T23:38:59.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19014" PostTypeId="2" ParentId="19009" CreationDate="2015-08-17T23:42:39.437" Score="29" Body="&lt;p&gt;Honestly? It's probably because they heard someone else do it, and thought it sounded cool (or otherwise just got it stuck in their head).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're 100% right - saying the runway name is, if slightly longer, certainly a bit more informative. It's the kind of thing that can help arriving pilots know which runway is in use, keeping later radio clutter (&quot;Um, uhh, Jeffco Traffic, um, say runway in use?&quot;) to a minimum for pilots already on frequency. Even a 'one runway airport' still has two runways (09/27, for example), and it's nice to know which one you should set up for when winds are light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The preferred terminology is more like &quot;Jeffco Traffic, 3AC, clear 29&quot;. &lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-08-18T05:33:05.920" LastActivityDate="2015-08-18T05:33:05.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19016" PostTypeId="1" AcceptedAnswerId="19033" CreationDate="2015-08-18T01:11:31.177" Score="24" ViewCount="5553" Body="&lt;p&gt;I ask this question because wings are pretty thin overall, but I am curious if you could make them more thin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/90IlN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/90IlN.jpg&quot; alt=&quot;airliner wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="6918" LastEditDate="2015-08-18T10:33:57.870" LastActivityDate="2018-11-02T14:14:25.900" Title="Could airliners' wings be thinner if no fuel were stored in them?" Tags="&lt;airliner&gt;&lt;fuel-tanks&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19019" PostTypeId="2" ParentId="18994" CreationDate="2015-08-18T01:55:23.967" Score="9" Body="&lt;p&gt;The primary purpose of yawing is to &lt;strong&gt;stop yawing&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes with long wings have a tendency called adverse yaw. Adverse yaw causes the plane to yaw away from the direction of turn when attempting to turn using ailerons and elevator. The more you try to turn left, the more the nose point right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big problem with adverse yaw (apart from it being potentially confusing to pilots) is that while the lift from the wings held at a bank angle is trying to turn the plane in one direction, the nose is going in the wrong direction eventually causing the plane to stall. This can make turning impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early aerodynamicists didn't fully appreciate adverse yaw because experiments with model planes tended to have the plane fly straight. It's not until you attempt a turn that you'd encounter adverse yaw. Even early glider pioneers didn't fully appreciate it much because a lot of the early hill hopping glider flights were also in straight lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among the first people to encounter and attempt to solve the problem of adverse yaw was the Wright brothers. Taking inspiration from other early glider pioneers and large kite fliers their early gliders didn't have a rudder. They found that it was unstable when the wings tip to either side (bank). What they experienced was adverse yaw. Their solution was to add a vertical stabilizer and it solved the problem for the most part. Later they made the rudder movable to allow the pilot to further correct for adverse yaw manually. We still teach this &quot;correction&quot; maneuver - it's called the coordinated turn.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-08-18T01:55:23.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19020" PostTypeId="2" ParentId="19016" CreationDate="2015-08-18T02:56:21.403" Score="27" Body="&lt;p&gt;Airplane wings are designed purely from aerodynamic and structural considerations. Supersonic fighters often have much thinner wings (and store fuel in the fuselage) because those are the requirements of supersonic flight. For subsonic (and transonic, which most modern airliners and business jets are -- over some parts of the wing the airflow is actually supersonic) flight, thick wings are fine, are structurally much better, and provide space for fuel tanks and the wheels.&lt;/p&gt;&#xA;" OwnerUserId="9826" LastActivityDate="2015-08-18T02:56:21.403" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19021" PostTypeId="2" ParentId="18975" CreationDate="2015-08-18T03:03:31.070" Score="1" Body="&lt;p&gt;The shortest answer is: in uncontrolled airspace, you fly IFR without a clearance (and no clearance is available); in controlled airspace, you cannot fly IFR without a clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the only real difference. Everything else (like weather minimums for VFR) follows from that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BTW Class E is controlled airspace, and has no specific entry requirements for VFR either.&lt;/p&gt;&#xA;" OwnerUserId="9826" LastActivityDate="2015-08-18T03:03:31.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19022" PostTypeId="2" ParentId="18930" CreationDate="2015-08-18T03:05:17.587" Score="4" Body="&lt;p&gt;For non-towered airports, there is no such regulation. The only actual regulation that might prevent two aircraft from occupying a given runway at the same time is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.7&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.13&lt;/a&gt;, which prohibits the operation of aircraft &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;in a careless or reckless manner so as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Want to line up and wait while someone else is rolling out? Touch down before the previous arrival has cleared the runway? They're not specifically prohibited - but neither is a good idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the size of the turnaround area, I would generally consider a landing while it's occupied unsafe - perhaps even &lt;em&gt;reckless&lt;/em&gt;. However, a takeoff with the turnaround occupied might be comparable to a &lt;a href=&quot;https://aviation.stackexchange.com/q/12031/136&quot;&gt;Line Up and Wait&lt;/a&gt; situation. The closest FAA guidance I can find comes from the Pilot's Handbook of Aeronautical Knowledge, in Appendix 1 - &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Appendix%201.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Runway Incursion Avoidance&lt;/a&gt; (p. 1-10):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTE: Line up and wait/holding in position is not recommended at nontowered airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's good common sense. But &quot;not recommended&quot;, in a document which is not legally binding, is far from an actual prohibition.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-18T03:05:17.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19023" PostTypeId="1" AcceptedAnswerId="19031" CreationDate="2015-08-18T04:29:14.880" Score="5" ViewCount="310" Body="&lt;p&gt;In the answer to this &lt;a href=&quot;https://aviation.stackexchange.com/questions/12610/is-there-any-application-where-the-crescent-wing-would-be-the-best-wing-planform&quot;&gt;question&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;Peter Kampf&lt;/a&gt; stated that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;In the majority of cases it is aerodynamically advantageous to vary sweep with relative thickness, but it is not structurally and economically efficient.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this the case?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-08-21T13:01:05.310" Title="Why is it advantageous to vary sweep angle with relative thickness?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19024" PostTypeId="2" ParentId="19008" CreationDate="2015-08-18T04:44:22.567" Score="5" Body="&lt;h2&gt;In general, no, you can't.&lt;/h2&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Public (Governmental) Use&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The FAA maintains a page on &lt;a href=&quot;https://www.faa.gov/uas/public_operations/&quot;&gt;Public Operations of UASs&lt;/a&gt;. There are a couple of ways governmental organizations (excluding the armed forces) can fly a UAS:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;It can fly in accordance with the limitations set out in &lt;a href=&quot;https://www.faa.gov/uas/media/Sec_331_336_UAS.pdf&quot;&gt;Public Law 112-95 Title I, Subtitle B, Section 334 (c)(2)(C)&lt;/a&gt;, which are that the FAA will:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(C) allow a government public safety agency to operate unmanned aircraft weighing 4.4 pounds or less, if operated—  &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(i) within the line of sight of the operator;&lt;br&gt;&#xA;    (ii) less than 400 feet above the ground;&lt;br&gt;&#xA;    (iii) during daylight conditions;&lt;br&gt;&#xA;    (iv) within Class G airspace; and&lt;br&gt;&#xA;    (v) outside of 5 statute miles from any airport,&#xA;    heliport, seaplane base, spaceport, or other location&#xA;    with aviation activities.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, obviously, that's a no-go for Bravo.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;It can apply for a &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/aaim/organizations/uas/coa/&quot;&gt;Certificate of Waiver or Authorization&lt;/a&gt; from the FAA, which &lt;code&gt;&quot;permits public agencies and organizations to operate a particular aircraft, for a particular purpose, in a particular area.&quot;&lt;/code&gt; &lt;a href=&quot;https://www.faa.gov/uas/public_operations/&quot;&gt;According to the FAA&lt;/a&gt;,&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA works with these organizations to develop conditions and limitations for UAS operations to ensure they do not jeopardize the safety of other aviation operations. The objective is to issue a COA with parameters that ensure a level of safety equivalent to manned aircraft. &lt;strong&gt;Usually, this entails making sure that the UAS does not operate in a populated area&lt;/strong&gt; and that the aircraft is observed, either by someone in a manned aircraft or someone on the ground to ensure separation from other aircraft in accordance with right-of-way rules. Common public uses today include law enforcement, firefighting, border patrol, disaster relief, search and rescue, military training, and other government operational missions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, unless you have a &lt;em&gt;really&lt;/em&gt; convincing argument, it sounds like the FAA is very unlikely to include in your COA authorization for your UAS to enter Class B (or get anywhere near it, for that matter.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Civil, Non-Hobbyist Operation&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The FAA also maintains a page on &lt;a href=&quot;https://www.faa.gov/uas/civil_operations/&quot;&gt;Civil Operations of UASs&lt;/a&gt;. That page summarizes how civil UAS operations can be approved as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are presently two methods of gaining FAA authorization to fly civil (non-governmental) UAS:  &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;a href=&quot;https://www.faa.gov/uas/legislative_programs/section_333/&quot;&gt;Section 333 Exemption&lt;/a&gt; – &lt;strong&gt;a grant of exemption in accordance with Section 333 AND a civil Certificate of Waiver or Authorization (COA)&lt;/strong&gt;; this process may be used to perform commercial operations in &lt;strong&gt;low-risk, controlled environments&lt;/strong&gt;. Instructions for filing a petition for exemption are available &lt;a href=&quot;https://www.faa.gov/uas/legislative_programs/section_333/how_to_file_a_petition/&quot;&gt;here&lt;/a&gt;.  &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Surely, operating in Class B isn't &quot;low risk&quot; (though I suppose you could argue it's &quot;controlled,&quot;) so this certainly seems like a no-go.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/sac/&quot;&gt;Special Airworthiness Certificate (SAC)&lt;/a&gt; – applicants must be able to describe how their system is designed, constructed, and manufactured, including engineering processes, software development and control, configuration management, and quality assurance procedures used, &lt;strong&gt;along with how and where they intend to fly&lt;/strong&gt;.  &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;a. &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/&quot;&gt;SAC in the experimental category&lt;/a&gt; – may be used for civil aircraft to perform research and development, crew training, and market surveys; however, &lt;em&gt;carrying persons or property for compensation or hire is prohibited&lt;/em&gt;. &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1021706&quot;&gt;FAA Order 8130.34&lt;/a&gt; is used by FAA inspectors to issue experimental airworthiness certificates and special flight permits to UAS. For more information, please contact the Airworthiness Certification Service, AIR-113, at 202-267-1575.  &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;If the FAA determines the project does not present an unreasonable safety risk, the local FAA Manufacturing Inspection District Office will issue a Special Airworthiness Certificate in the Experimental Category with operating limitations applicable to the particular UAS.&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;b. A UAS &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/sac/&quot;&gt;type and airworthiness certificate in the Restricted Category&lt;/a&gt; (14 CFR § 21.25(a)(2) and § 21.185) for a special purpose or a type certificate for production of the UAS under 14 CFR § 21.25(a)(1) or § 21.17. For more information, please contact the Los Angeles Aircraft Certification Office at 562-627-5200.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;strong&gt;Bold&lt;/strong&gt; emphasis is mine, &lt;em&gt;italics&lt;/em&gt; emphasis is from the FAA.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For UASs with a Special Airworthiness Certificate, &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1021706&quot;&gt;FAA Order 8130.34C&lt;/a&gt; specifies in Chapter 3, Section 1.3 (Flight Test and Operating Area) that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All proposed flight test and operating areas outside of restricted airspace must be approved by the FAA. Flight test and operating areas will be coordinated with the air traffic component of AFS-80.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The flight test area and operating area must be over open water, or sparsely populated areas, having light air traffic. The FAA is required to evaluate each application to determine that the proposed flight area does not exceed that which is reasonably required to accomplish the program.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Certainly, Class B doesn't qualify as &quot;sparsely populated areas, having light air traffic,&quot; so this, too, seems to be a no-go.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-08-18T04:44:22.567" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19026" PostTypeId="1" AcceptedAnswerId="19032" CreationDate="2015-08-18T06:33:03.553" Score="5" ViewCount="16013" Body="&lt;p&gt;I asked myself a question why are so many ATR involved in accidents in the past years?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ATR-72, 16 October 2013, Lao Airlines Flight 301&lt;/li&gt;&#xA;&lt;li&gt;ATR-42, 19 October 2013, P2-PXY, Air Niugini&lt;/li&gt;&#xA;&lt;li&gt;ATR-72, 23 July 2014, TransAsia Airways Flight 222&lt;/li&gt;&#xA;&lt;li&gt;ATR-72, 02 February 2015, TransAsia Airways Flight 235&lt;/li&gt;&#xA;&lt;li&gt;ATR-42, 16 August 2015, Trigana Air Service Flight 257&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3734" LastActivityDate="2019-02-28T05:21:41.183" Title="Why are so many ATR involved in accidents in the past years`?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;atr-72&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19027" PostTypeId="2" ParentId="19007" CreationDate="2015-08-18T06:53:15.003" Score="5" Body="&lt;p&gt;The overall centre of lift must be coincident (in the horizontal plane) with the centre of gravity, otherwise the plane would tip over forward or backward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since most planes have a large wing that contributes most of the lift and a small horizontal stabilizer that only contributes a little bit, the main wing needs to be close to the centre of gravity. So the wing is mounted further aft if the centre of gravity is further aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the &lt;em&gt;cargo&lt;/em&gt; will always have its centre of gravity near the centre of the fuselage. So if the empty aircraft has aft centre of gravity, loading it will cause larger change of the CG position and for this it needs larger horizontal stabilizer so it can provide enough balancing force.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-18T06:53:15.003" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19028" PostTypeId="2" ParentId="170" CreationDate="2015-08-18T07:20:38.887" Score="2" Body="&lt;p&gt;Spanair Flight 5022 crashed during takeoff because flaps were not deployed and the systems involved in warning the pilots about this event, failed. I'm not an expert and I don't know the chances of this event to happen, but if you are about to take off and see no flaps deployed, then that might be a reason for warning the crew. &lt;/p&gt;&#xA;" OwnerUserId="9745" LastActivityDate="2015-08-18T07:20:38.887" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19029" PostTypeId="1" CreationDate="2015-08-18T07:53:22.967" Score="0" ViewCount="657" Body="&lt;p&gt;Let an aircraft in a steady level flight be trimmed at certain speed. A level and steady flight at a higher speed can be achieved by changing throttle and elevator together ( and not just by changing elevator or throttle alone). How?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastActivityDate="2015-08-18T20:30:31.603" Title="Requirements for Steady Level flight at various speeds" Tags="&lt;aerodynamics&gt;&lt;flight-training&gt;&lt;flight-controls&gt;&lt;throttle&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2015-08-18T22:15:37.097" ContentLicense="CC BY-SA 3.0" />
  <row Id="19030" PostTypeId="1" CreationDate="2015-08-18T07:57:13.570" Score="1" ViewCount="7060" Body="&lt;p&gt;Out of turns, stalls and climbs, which of the basic maneuvers increases the load factor on an airplane as compared to straight and level flight?&lt;/p&gt;&#xA;" OwnerUserId="8547" LastEditorUserId="1696" LastEditDate="2015-08-18T15:45:59.950" LastActivityDate="2015-08-18T15:45:59.950" Title="What types of maneuvers increase the load factor on the aircraft?" Tags="&lt;aerodynamics&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19031" PostTypeId="2" ParentId="19023" CreationDate="2015-08-18T08:14:03.653" Score="5" Body="&lt;p&gt;Here's a high speed reason:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR: They counter each other's effect on the wave drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Thickness versus wave drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, a thicker airfoil has a bigger curvature, and will accelerate the airflow around it more. This leads to more lift for the same speed. However, at cruise speed, closer to M=1, sonic effects will occur. This will lead to increased drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can seen from the figure below, with increasing $t/c$, the value of $c_d$ is higher, and the rapid increase associated to wave drag starts earlier. The value of $M$ at which this occurs is called the Drag Divergence Mach number, $M_{DD}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o0OQT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o0OQT.jpg&quot; alt=&quot;CDW vs t/c&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://soliton.ae.gatech.edu/people/lsankar/AE3903/Harris.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: NASA supercritical airfoils: A matrix of family-related airfoils&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sweep versus wave drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a sweep angle is present, we can decompose the velocity in two components, of which only the one perpendicular to the chordline ($V_\bot$) is effecting lift (and thus wave drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By increasing the sweep, we can reduce the value of $V_\bot$, allowing the airfoil to experience a lower value of $M$, thus delaying the drag rise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9Hmod.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Hmod.jpg&quot; alt=&quot;CDW vs sweep&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://repository.tudelft.nl/assets/uuid:3b1c6432-cfbf-4fec-894b-9f6b870015f5/MSc_Thesis_Mariens.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: Wing Shape Multidisciplinary Design&#xA;Optimization&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Combined effects&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, for wave drag, the two counteract eachother. If you have a certain value of $t/c$ and a certain $\Lambda$, this will lead to a certain $M_{DD}$. If for some reason, you want to increase the value of $t/c$, the wave drag increase will come earlier, leading to a lower $M_{DD}$. To maintain the same $M_{DD}$, you could counteract the effects of a larger $t/c$ by increasing $\Lambda$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is clearly shown by the emperic Korn-Lock-Mason method, which states:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ M_{DD} = \frac{K_A}{cos \Lambda} + \frac{t/c}{cos^2 \Lambda} +\frac{c_l}{cos ^3\Lambda} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This also shows the effects of lift on the value of $M_{DD}$.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-08-21T13:01:05.310" LastActivityDate="2015-08-21T13:01:05.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19032" PostTypeId="2" ParentId="19026" CreationDate="2015-08-18T09:42:24.700" Score="20" Body="&lt;p&gt;&lt;a href=&quot;http://www.mpwt.gov.la/attachments/article/880/028.11.2014_Press%20Release%20on%20the%20final%20Report%20Aircraft%20Accident%20Investigation%20-%20QV%20301_Englis%20version.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATR-72, 16 October 2013, Lao Airlines Flight 301&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The probable cause of this accident were the sudden change of weather&#xA;  condition and the flight crew's failure to properly execute the&#xA;  published instrument approach, including the published missed approach&#xA;  procedure, which resulted in the aircraft impacting the terrain.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aic.gov.pg/pdf/AIC13-1007%20P2-PXY%20Preliminary%20v2.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATR-42, 19 October 2013, P2-PXY, Air Niugini&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to released information this cargo aircraft overran the runway after the crew aborted the take-off above V&lt;sub&gt;r&lt;/sub&gt; after experiencing pitch control problems. The final report of this accident is not yet published but a preliminary report is available.  The investigation focusses on the payload distribution which may have caused imbalance leading to the perceived control problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.asc.gov.tw/main_en/docaccident.aspx?uid=343&amp;amp;pid=296&amp;amp;acd_no=182&quot; rel=&quot;noreferrer&quot;&gt;ATR-72, 23 July 2014, TransAsia Airways Flight 222&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft crashed on final approach in low visibility conditions (800 meters). During the initial approach the crew had requested and ILS approach (precision approach) to runway 02 but then changed their minds and asked for a VOR approach (non-precision approach) to runway 20. During the approach, after deactivation of the autopilot, the aircraft deviated 340 meters to the left and the crew subsequently announced they were going around. Shortly afterwards the aircraft hit tree tops and impacted residential buildings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final report is expected in October 2015. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me it seems the probable cause is the failure of the flight crew to properly execute the published instrument approach including the published missed approach procedure which resulted in the aircraft impacting the trees and buildings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.asc.gov.tw/main_en/docaccident.aspx?acd_no=191&amp;amp;uid=343&amp;amp;pid=296&quot; rel=&quot;noreferrer&quot;&gt;ATR-72, 02 February 2015, TransAsia Airways Flight 235&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The investigation into this accident is still running, only some preliminary information has been published. Preliminary data indicates that about 36 seconds after takeoff the engine no.2 auto-feathered, about 46 seconds subsequent to auto-feather the engine no.1 was shut off by the crew, resulting in loss of all thrust. The aircraft subsequently descended, stalled and crashed into a river. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATR-42, 16 August 2015, Trigana Air Service Flight 257&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This accident occurred just a couple of days ago so there are few facts known yet and no preliminary findings are published. I will not speculate about the probable cause of this accident. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The common thread in the first four accidents seems to be the failure to comply with established procedures resulting in the loss of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In two cases (Lao Airlines Flight 301 and TransAsia Airways Flight 222) the flight crew flew a controllable aircraft into the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the Air Niugini crash improper loading of the aircraft is likely to be the cause, resulting in the aircraft being not trimmed correctly for take-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crash of TransAsia Airways Flight 235 is the only crash that involved an aircraft system malfunction (engine 2 failure). However, the ATR-72 can fly on a single engine so the failure itself should not have been fatal. The crew then shut down the other engine (number 1) which sealed the aircraft's fate. It is too early to conclude that the crew didn't follow the correct procedures here; for example there may have been ambiguous indications from the engine instruments that led them to believe that engine no. 1 had failed. However with the information currently available it seems that the crew did not follow the correct procedures for shutting down a failed engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high number of crashes involving an ATR aircraft seems not to be related to the model itself, but to the safety culture and lack of training within a number of airlines operating the aircraft. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-08-18T20:25:10.587" LastActivityDate="2015-08-18T20:25:10.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19033" PostTypeId="2" ParentId="19016" CreationDate="2015-08-18T09:49:12.393" Score="29" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing thickness is primarily dictated by structural demands. It has to provide an aerodynamic fairing for the wing spar. Making it thinner would drive up the mass of the structure inside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To simplify things, imagine the wing &lt;a href=&quot;https://en.wikipedia.org/wiki/Spar_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;spar&lt;/a&gt; as an I-beam. It has two flanges which carry tension and compression loads, and a web between the flanges to transmit shear loads. The bending moment carried by the spar is the product of the forces in the flanges and the distance between them. If you reduce the distance, the forces need to increase to keep the bending moment constant. Bigger forces will result in bigger flanges to keep the stresses in the material below the &lt;a href=&quot;https://en.wikipedia.org/wiki/Yield_(engineering)&quot; rel=&quot;noreferrer&quot;&gt;yield&lt;/a&gt; stress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Limiting the thickness is the desire to fly at a &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85/11948#11948&quot;&gt;certain Mach number&lt;/a&gt;. A moving wing needs to push the air ahead of it aside, and thicker wings need to do more pushing. This results in a higher acceleration of the flow around the wing, and thicker wings have a lower &lt;a href=&quot;https://aviation.stackexchange.com/questions/11918/is-there-a-surface-of-a-commercial-jet-exposed-to-air-flow-at-speed-near-mach-1&quot;&gt;critical Mach number&lt;/a&gt; (the flight Mach number when local flow reaches Mach 1). This drag penalty is especially severe in supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thicker wings also help with creating higher maximum lift coefficients, up to a point. The plot below (taken from &lt;a href=&quot;http://www.aeronautics.nasa.gov/docs/rpt460/discuss.htm&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; website) shows that an airfoil thickness of 12% gives the best results, which helps to keep the wing area low. A thicker wing also makes it easier to integrate complex high-lift devices, which again helps to reduce wing area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Pk4Ec.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Pk4Ec.gif&quot; alt=&quot;Variation of maximum lift with thickness&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The resulting wing thickness is always a compromise, and the fuel volume is only the result of that compromise. If a wing needs to store more fuel, the designers will choose a lower &lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing/8797?s=12%7C0.1163#8797&quot;&gt;aspect ratio&lt;/a&gt;, but will leave the relative thickness unchanged. If less fuel is required, the tanks will become smaller, and again the thickness will not change.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-18T10:56:26.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19034" PostTypeId="2" ParentId="14509" CreationDate="2015-08-18T11:35:09.350" Score="-1" Body="&lt;p&gt;I don't think it was the engines alone that allowed supercruise (supersonic cruise without reheat). On Concorde, the engines engaged reheat in order to accelerate in level flight from subsonic to supersonic. One of the main reasons why Concorde had so much more range than the TU144 (which had to stay in reheat to stay supersonic), is the design of the wing. The Concorde wing evolved into a more complex shape during its development (I think between the first prototype and the production Concordes) specifically for this reason. If you look at the Concorde from the front the wing tips kind of sweep downwards. See &lt;a href=&quot;http://www.concordesst.com/wing.html&quot; rel=&quot;nofollow&quot;&gt;http://www.concordesst.com/wing.html&lt;/a&gt; for more information. Even the great Kelly Johnson didn't do it this way for the SR-71, which stays in reheat the entire time it is supersonic.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-18T11:35:09.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19035" PostTypeId="2" ParentId="19029" CreationDate="2015-08-18T12:47:00.303" Score="0" Body="&lt;p&gt;I'm not sure if the question is &lt;em&gt;how&lt;/em&gt; or &lt;em&gt;why&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume that the throttle is changed (let's say increased) in level flight. The following things happen:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The speed increases.&lt;/li&gt;&#xA;&lt;li&gt;The increase in speed increases the lift produced by the wing and the aircraft attitude changes (it pitches up) and the aircraft is no longer in level flight.&lt;/li&gt;&#xA;&lt;li&gt;In order to trim this, the elevator correction has to be applied.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;On the other hand, assume that the elevator is used to pitch the aircraft down. Then the following things happen:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The lift (and drag) decreases and the speed increases.&lt;/li&gt;&#xA;&lt;li&gt;In order to maintain the speed, the engine power has to be reduced.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So, its not possible to maintain level flight at a set speed &lt;em&gt;at a given altitude&lt;/em&gt; using only throttle or elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, at different altitudes the aircraft will be trimmed for different power settings for fixed elevator setting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to understand this is that the energy is conserved and if the kinetic energy is changed (by changing the speed), the potential energy (altitude) should also be changed for level flight. Otherwise the aircraft will trim itself at another stable altitude. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-18T12:47:00.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19036" PostTypeId="1" AcceptedAnswerId="19040" CreationDate="2015-08-18T12:59:29.387" Score="9" ViewCount="5405" Body="&lt;p&gt;When a pilot loses radio contact with ATC, there are standard procedures to follow, e.g. squawk 7600, observe the traffic pattern, observe the red / green light gun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other side, if a controller attempts to contact an aircraft and gets no response, what will they do? Assume that radar contact is not lost, or the controller is not equipped with radar.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: Let say a controller spotted a 7600. What's next?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-08-18T13:07:25.240" LastActivityDate="2015-08-18T16:06:56.927" Title="What will air traffic controllers do when radio contact is lost?" Tags="&lt;air-traffic-control&gt;&lt;emergency&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19037" PostTypeId="2" ParentId="19030" CreationDate="2015-08-18T12:59:33.440" Score="1" Body="&lt;p&gt;I'm assuming you mean structural loading, not things like passenger loading.  If you think about it generally, ANY maneuver or change of configuration changes the loads on an aircraft.  I would also contend that any change in loading &quot;increases&quot; the load on at least some of the components of an aircraft.  As an example, &quot;reducing&quot; the G-loading on an aircraft that is in straight-and-level flight by pushing the nose down will increase the load on other parts of the airframe even though the &quot;net&quot; loading on the aircraft has decreased.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to which maneuvers generate more loading, it's completely dependent on the design and behavior of the airplane, as well as how aggressively the pilot has provided control input.  I think many people would think that a stall provides more loading than a climb, but I've stalled a piper cub so gently that you could barely feel it - but if you pull a high performance airplane into a steep climb you can easily exceed 5g or more.  &lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-08-18T12:59:33.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19038" PostTypeId="2" ParentId="19036" CreationDate="2015-08-18T13:15:01.913" Score="3" Body="&lt;p&gt;As you note, there are procedures to follow in lost comm scenarios, and ATC will expect you to follow these procedures.  In turn, they will continue to hand you off to subsequent controllers toward your destination and keep other aircraft out of your way.  They will attempt to establish one-way comms or comms via alternate methods (ACARS, SELCAL, satellite phone).  If comms are impossible, they will work other airplanes to maintain separation with you and the ability to do this easily comes from established lost comm procedures for pilots to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For IFR lost comms, the procedures they expect you to follow are given in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1185&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.195&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in VMC or encounter VMC you will continue flight under VFR land as soon as practical.  If ATC sees you break off of your route and descend toward an airport, they will coordinate to make sure you successfully land and otherwise dispatch S&amp;amp;R to find you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in IMC or cannot comply with continuing under VFR (e.g. your operation is limited to IFR ops) then ATC will expect you to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Follow the route: &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;that you were last cleared for&lt;/li&gt;&#xA;&lt;li&gt;If you were on radar vectors, fly direct to the fix you were being vectored toward&lt;/li&gt;&#xA;&lt;li&gt;If you do not have an assigned route, fly the expected route&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fly at the highest of the following altitudes:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Your assigned flight level or altitude&lt;/li&gt;&#xA;&lt;li&gt;The minimum altitude for your operation&lt;/li&gt;&#xA;&lt;li&gt;The expected flight level or altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The regs basically boil down to &quot;fly your clearance and anything we told you to 'expect'&quot;.  If you lost comms shortly after takeoff while on radar vectors, you'd fly direct to the fix you were being vectored to (e.g. the first fix on your flight plan) while climbing to your expected flight level (e.g. your cruising altitude).  You'll then fly your cleared route to your destination, descending in accordance with your arrival procedure and then flying direct to an approach fix and flying the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC will expect this from you and they will vector / sequence other airplanes out of your way to maintain separation.  They can reliably do this because your behavior is well-defined and as long as you do what is expected of you, you are relatively easy to work around.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-08-18T13:24:48.653" LastActivityDate="2015-08-18T13:24:48.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19039" PostTypeId="1" CreationDate="2015-08-18T13:36:24.113" Score="3" ViewCount="3955" Body="&lt;p&gt;Was wondering if the pilot would faint, could g-force be enough to maybe break the neck bone with the head and weight of a helmet being pulled downwards. Another relay to this is the effects on the inside of the body, more specifically, the brain. Like a boxer, after taking a few too many knockouts. Is there a limit, or an event horizon to permanent brain damage and bone structure deterioration concerning g-force and pilots in aircraft maneuvers?&lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="9105" LastEditDate="2015-08-18T13:50:44.380" LastActivityDate="2015-08-20T14:51:06.760" Title="Can excessive G-force break or dislocate bones during pilot maneuvers?" Tags="&lt;g-forces&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19040" PostTypeId="2" ParentId="19036" CreationDate="2015-08-18T13:53:13.357" Score="13" Body="&lt;p&gt;You didn't mention any specific jurisdiction but for the FAA, the expected actions are in the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC orders&lt;/a&gt;. Section 5-2-8 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When you observe a  Code 7600  display, apply the procedures in para&#xA;  10−4− 4, Communications Failure&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 10-4-4 gives general instructions for comms failure, it's too long to quote in full but the first paragraph summarizes it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the event of lost communications with an aircraft under your&#xA;  control jurisdiction use all appropriate means available to&#xA;  reestablish communications  with the aircraft. These may include, but&#xA;  not be limited to, emergency frequencies, NAVAIDs that are equipped&#xA;  with voice  capability, FSS,  Aeronautical Radio Incorporated (ARINC),&#xA;  etc.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The instructions suggest some specific actions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Broadcast via NAVAID frequencies&lt;/li&gt;&#xA;&lt;li&gt;Ask the aircraft to use its transponder or make turns to acknowledge instructions&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If comms haven't been reestablished within 5 minutes, ATC is instructed to consider it as suspicious:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If radio communications have not been (re) established  with the&#xA;  aircraft after 5 minutes, consider the aircraft’s or pilot’s activity&#xA;  to be suspicious and report it to the FLM/CIC per FAA Order JO 7610.4,&#xA;  Chapter 7, Hijacked/Suspicious Aircraft Reporting and Procedures&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 10-2-5 also says that lost comms are an emergency from the ATC perspective and should be escalated to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_Control_Center&quot;&gt;ARTCC&lt;/a&gt;. If comms aren't restored within 30 minutes then the aircraft is considered overdue, which triggers another set of procedures listed in section 10-3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for clearing airspace or whatever, there are no specific instructions in the orders, it just says that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When an IFR aircraft experiences two-way radio communications failure,&#xA;  air traffic control is based on anticipated pilot actions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, ATC expects IFR pilots to follow lost comms procedures as per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1185&quot;&gt;14 CFR 91.185&lt;/a&gt; and will direct other traffic accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, one 'routine' lost comms scenario is when ATC can't contact an aircraft because of poor radio coverage. This happens a lot with smaller aircraft (which fly relatively low) operating in remote areas and ATC might ask another aircraft, usually a higher-flying airliner if possible, to contact the first aircraft and relay their call: &lt;em&gt;N12345, this is BigAir 123 with relay from Denver Center&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-08-18T16:06:56.927" LastActivityDate="2015-08-18T16:06:56.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19041" PostTypeId="2" ParentId="19030" CreationDate="2015-08-18T14:01:24.280" Score="2" Body="&lt;p&gt;The load factor of an aircraft is given as the ratio of lift to weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. $n = \frac{L}{W}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, an maneuver that changes any of these two forces acting on the aircraft causes a change in the load factor. Usually, it is the lift which is considered the variable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider an aircraft in a &lt;em&gt;level&lt;/em&gt; turn. In addition to the lift and weight, the aircraft experiences centrifugal force, which is counteracted b the horizontal component of the lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/86shc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/86shc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;Courtesy: www.rainierflightservice.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a bank angle of $\theta$, it can be shown that the load factor can be given as,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$n = \frac{1}{cos\theta}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, as the bank becomes 'tighter', the load factor increases. A load factor greater than one will cause the stall speed to increase by the square of the load factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, as the load factor is increased, the aircraft minimum speed should be increased to prevent stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircrafts in &lt;em&gt;steady&lt;/em&gt; climb, the principle is essentially the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oqtwz.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oqtwz.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Picture Source: classicairshows.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here, the weight is less than the lift and as such, the load factor is (slightly) less than one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft stalls in level flight or unaccelerated straight climb, the lift becomes zeros and the load factor also becomes zero.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-18T14:01:24.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19042" PostTypeId="2" ParentId="19039" CreationDate="2015-08-18T14:02:25.950" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Can excessive G-force break or dislocate bones during pilot maneuvers?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the pilot remains conscious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example see &lt;a href=&quot;http://medind.nic.in/iab/t00/i2/iabt00i2p1o.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://medind.nic.in/iab/t00/i2/iabt00i2p1o.pdf&lt;/a&gt; which describes compression fractures suffered by pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EUaiJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EUaiJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-19T07:56:12.390" LastActivityDate="2015-08-19T07:56:12.390" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19043" PostTypeId="1" AcceptedAnswerId="19046" CreationDate="2015-08-18T15:03:45.027" Score="7" ViewCount="2825" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1211&quot;&gt;FAR 91.211(a)&lt;/a&gt; requires supplemental oxygen for all passengers above 15,000 feet.  Are there any health implications of a 5 hour flight at around 14,000 feet on children without any supplemental oxygen?  Obviously the flight crew would be wearing supplemental oxygen as required by the FAA above 12,500 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read that babies under 3 months do not have mature enough lungs for altitude stress, so for the sake of this question, let's assume the children are over 6 months with no existing health conditions to worry about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is for a non-pressurized general aviation aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="64" LastEditDate="2015-08-18T16:52:37.910" LastActivityDate="2015-08-19T11:15:38.833" Title="Is flying at 14,000 MSL safe for children without supplemental oxygen?" Tags="&lt;safety&gt;&lt;medical&gt;&lt;oxygen&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19045" PostTypeId="2" ParentId="19016" CreationDate="2015-08-18T15:45:50.633" Score="8" Body="&lt;p&gt;Possibly, but having no fuel in the wing would likely be an effect of making wings thinner, rather than a driving cause.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the past, thin airfoil theory ruled the day, and designers used external trusses to support two lifting surfaces in a biplane configuration.  Check out the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Dragon&quot;&gt;De Havilland Dragon&lt;/a&gt;, which used the RAF 15 airfoil section (max t/c of 6.5%), as an example.  Compare this to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_247&quot;&gt;Boeing 247&lt;/a&gt;, which was introduced one month later (May vs. April 1933) and also carried ten passengers, but used a single cantilever wing, without external supports.  Its wing section, the Boeing 106 (max t/c of 13.5%), was thick enough to contain an internal support structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main benefit of having all your structural members contained in the wing is the reduced drag.  You get some other benefits as well, like delayed stall due to the rounded leading edge, and room to store your fuel due to the higher enclosed volume.  It's unlikely that any serious airliner design is going to return to a biplane configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, thanks to the wealth of materials and design tools the engineers have, the wing thickness seems to be around 10% based on glancing at a few Airbus/Boeing offerings.  Usually, a modern design will change the airfoil profile from root to tip, so it will be higher in some places and lower in others.  It's possible that if these techniques were applied to biplane designs, we could come up with some really thin wings, but the airplane would have high drag and likely wouldn't sell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, some concepts arrange the wings in ways that might let you get away with this.  In particular, Lockheed Martin has proposed a box-wing concept (for which I couldn't find the name) and Boeing has studied a design with braced wings called Subsonic Ultra Green Aircraft Research (SUGAR).  If one of these designs ends up reducing the amount of stiffness needed in the wing spar, the designers would likely reduce the spar (and thus wing) thickness to save weight.  Depending on how much thickness they shave off, it might no longer be worthwhile to store fuel in the wing.&lt;/p&gt;&#xA;" OwnerUserId="9845" LastActivityDate="2015-08-18T15:45:50.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19046" PostTypeId="2" ParentId="19043" CreationDate="2015-08-18T16:11:27.237" Score="20" Body="&lt;p&gt;Let me start out by saying that Aviation Stack Exchange is not a substitute for medical advice. Most of us aren't doctors (though I have medical training I am certainly not a doctor), and even if we were doctors we are not &lt;em&gt;your&lt;/em&gt; doctor and we don't know your medical history (or your child's medical history).&lt;br&gt;&#xA;If you're going to be flying with your kids in an unpressurized aircraft consult your pediatrician for their recommendation on supplemental oxygen. There are a number of factors at play, and your doctor will be able to consider all of them and give you comprehensive advice.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That said, let's talk about oxygen in general terms.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a lot of good information on supplemental oxygen use out there: &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Pilot-and-Passenger-Physiology/Oxygen-Use-in-Aviation&quot;&gt;AOPA talks about it here&lt;/a&gt;, and &lt;a href=&quot;http://www.dr-amy.com/rich/oxygen/&quot;&gt;this website has a very detailed explanation, written by a doctor&lt;/a&gt; which get into what's going on as altitude increases (and the partial pressure of oxygen in your lungs decreases).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By regulation you are required to provide supplemental oxygen:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;to the flight crew if you're above 12,500 feet for more than 30 minutes.&lt;/li&gt;&#xA;&lt;li&gt;to the flight crew if you're above 14,000 feet for ANY length of time.&lt;/li&gt;&#xA;&lt;li&gt;to everyone onboard if you're above 15,000 feet for ANY length of time. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Using the handy chart in the second website that equates to oxygen saturations (SpO2) of roughly 88%, 82%, and 76%, assuming you're breathing ambient air for an extended period of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put this into perspective if you come to the hospital with an oxygen saturation below 90% you will almost universally be put on supplemental oxygen, and most guidelines call for maintaining SpO2 above 92%. (In aviation terms, the partial pressure of oxygen at 10,000 feet usually results in SpO2 around 90%).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So with that information the question now becomes &quot;What is your standard of care for your passengers?&quot; - the FAA sets &lt;em&gt;minimum requirements&lt;/em&gt; in the regulations, and they are mainly focused on making sure the flight crew does not become impaired (they are less concerned about your passengers getting loopy, as long as the pilot is OK), but you as a pilot are free to set higher standards based on your own understanding of physiology and aeromedical factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't tell you what you should do, but I &lt;em&gt;can&lt;/em&gt; tell you what I do: On any flight above 10,000 feet I carry supplemental oxygen, I use it, and I provide it to my passengers.&lt;br&gt;&#xA;I also carry a &lt;a href=&quot;http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias%3Daps&amp;amp;field-keywords=pulse+oximeter&quot;&gt;pulse oximeter&lt;/a&gt; in the aircraft to check oxygen saturation (SpO2) on myself or my passengers as needed (and I set the oxygen flow rate based on having the worst person in the aircraft above 90%).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="4043" LastEditDate="2015-08-19T11:15:38.833" LastActivityDate="2015-08-19T11:15:38.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19047" PostTypeId="1" AcceptedAnswerId="19062" CreationDate="2015-08-18T16:14:44.913" Score="11" ViewCount="988" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Reduced_gravity_aircraft&quot; rel=&quot;nofollow&quot;&gt;Reduced gravity aircraft&lt;/a&gt; are basically airliners without passengers seats. As airliners, those aircraft were not designed to fly for a long time in zero-G. Specifically engines were not designed to be fed with fuel for several tenth of seconds in reduced gravity conditions. I'm aware that aerobatic aircraft are equipped with devices to feed the engine in negative-G conditions for a limited amount of time, but what about the reduced gravity aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: aerobatics aircraft are equipped with header tanks and/or &lt;a href=&quot;http://science.howstuffworks.com/transport/flight/modern/question252.htm&quot; rel=&quot;nofollow&quot;&gt;flop tube&lt;/a&gt; able to get fuel in tank even if flying inverted (e.g. flop tube's end goes to the bottom of the tank, bottom defined in Earth frame of reference, whatever the attitude of the airplane). This design allow pipes to always be inside the liquid fuel of the fuel tank, and thus pumps can do there job (pump liquid). But when in zero G, liquid is no longer attracted toward one side of the tank (either the bottom or other side) and thus pipes may be fed with a mix of air (or whatever gas or vapor that is inside the fuel tank) and liquid fuel. Pressurized tanks do not change this. Yet, engine must be fed in fuel for several tenth of seconds in those condition, and I doubt fuel contained in pipes can last more than few seconds. Devices to fed a reduced gravity aircraft's engine should be different from the one in aerobatics in at least two way:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;aerobatics are designed to operate in inverted flight (not zero-G) and are in zero-G condition for a small amount of time (less than a couple of aerobatic maneuvers before being again in normal or inverted flight)&lt;/li&gt;&#xA;&lt;li&gt;reduced gravity aircraft are airliners (may be modified, but how?)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="5517" LastEditDate="2016-04-08T13:37:13.857" LastActivityDate="2016-04-08T13:37:13.857" Title="Are engines fed differently in reduced gravity aircraft?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19048" PostTypeId="2" ParentId="19043" CreationDate="2015-08-18T16:17:05.443" Score="7" Body="&lt;p&gt;There are always health implications at higher altitudes, even those approved by the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Legally you are not prevented from flying at this altitude since the FAA does not stipulate an age for that particular FAR. You &lt;strong&gt;SHOULD&lt;/strong&gt; consult a pediatrician on the specifics of you trip and its effects on children of the age you intend to carry. A 3 month old baby and a 4 year old kid are two very different things. If you have not seen it this &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Pilot-and-Passenger-Physiology/Oxygen-Use-in-Aviation&quot;&gt;AOPA article&lt;/a&gt; covers everything nicely. It should also be noted that breathing pure O₂ can also be harmfull when its not needed. You &lt;strong&gt;SHOULD NOT&lt;/strong&gt; assume that a solution to the problem is to provide supplemental 02 to children to counter what ever different effects they see due to their differing bodies. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do intend on this you should read up on the &lt;a href=&quot;http://www.webmd.com/asthma/guide/hypoxia-hypoxemia&quot;&gt;signs of hypoxia&lt;/a&gt; in both adults and children. You should also carry an &lt;a href=&quot;http://www.sportys.com/pilotshop/oxi-plus-pro-pulse-oximeter.html&quot;&gt;O₂ meter&lt;/a&gt; (possibly one for every occupant (Im not sure what the regs are on that)). I would also consider carrying something &lt;a href=&quot;http://www.sportys.com/pilotshop/boost-oxygen-22-oz.html&quot;&gt;like this&lt;/a&gt; as a back up source of O₂. The most important thing that you need to plan for is the ability to divert (or descend substantially) in route should you begin to see signs of hypoxia. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;DISCOLURE:&lt;/em&gt;&lt;/strong&gt; I am not a doctor (or medical professional of any kind) and this information should be used a guidance and not taken as hard and fast fact. You should always consult a medical professional in cases like this. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-18T20:27:26.533" LastActivityDate="2015-08-18T20:27:26.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19049" PostTypeId="2" ParentId="19026" CreationDate="2015-08-18T19:28:34.247" Score="4" Body="&lt;p&gt;More of an issue of pilot training, weather, safety of the airline and the country's regulator in general. ATRs are popular in regions that encompass many islands, hence the application in Southeast Asia. Some of these airlines are &quot;poor&quot; so they cannot afford to operate larger jet aircraft, nor would operating such an aircraft make sense in economical terms for many of the routes they operate. Would say that it is circumstantial and not a problem with ATR aircraft, per se.&lt;/p&gt;&#xA;" OwnerUserId="9279" LastActivityDate="2015-08-18T19:28:34.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19050" PostTypeId="1" CreationDate="2015-08-18T19:54:52.683" Score="5" ViewCount="3139" Body="&lt;p&gt;If a 737-800 has no power ('dead' airplane), is it still possible to set the parking brake on? If so, how?&lt;/p&gt;&#xA;" OwnerUserId="9849" LastEditorUserId="62" LastEditDate="2015-08-18T23:53:27.810" LastActivityDate="2015-08-21T05:06:14.350" Title="Can the parking brake be set on an 737-800 if the aircraft has no power?" Tags="&lt;boeing-737&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19051" PostTypeId="2" ParentId="18980" CreationDate="2015-08-18T19:58:38.273" Score="2" Body="&lt;p&gt;Search &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/&quot; rel=&quot;nofollow&quot;&gt;directly on the FAA page&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2015-08-18T19:58:38.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19052" PostTypeId="2" ParentId="19029" CreationDate="2015-08-18T20:30:31.603" Score="2" Body="&lt;p&gt;From a purely practical standpoint, let's say you're in a Cessna 172 (a common light aircraft often used for training) and you're in economy cruise at 2400 rpm at 6,000 feet on a standard day. According to the cruise performance chart I have here, you would be using 60% power, burning 6.8 gph, and have a true airspeed of 109 kts. You're hand flying the airplane as it has no autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the cute gal that you've talked into taking this trip with you mentions that she's beginning to need a bathroom. You neglected to bring along a urinal (and maybe more than a urinal is needed), so you decide to speed up to the maximum cruise speed for 6,000 feet. You consult the cruise performance chart and see that you can get 75% power at 2600 rpm. That will increase your cruise speed to 120 kts at the cost of burning 8.4 gph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would smoothly increase the rpm to 2600. As the power came up, you would have to hold a little forward pressure on the elevator to keep from climbing. If you're used to the airplane, you might unconsciously reach down to the trim wheel and roll in a little down elevator. In any event, you will eventually want to trim out the down elevator force you're holding on the control wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you set 2600 rpm to start the speed up, you'll notice that the rpm goes a little above 2600 as your speed increases (this is a fixed pitch propeller), so you monitor and adjust the rpm as necessary to settle on 2600 rpm with elevator forces trimmed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an autopilot with an altitude hold function but that doesn't control the power, all you'll have to do is control the power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an autopilot with FADEC, just set what you want and it will do all the work from there.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-08-18T20:30:31.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19053" PostTypeId="1" AcceptedAnswerId="19083" CreationDate="2015-08-18T21:00:54.597" Score="1" ViewCount="582" Body="&lt;p&gt;As title says, which book/web site/etc.. are available for learning proper communication (for Private Pilot License)?&lt;/p&gt;&#xA;" OwnerUserId="7245" LastEditorUserId="19" LastEditDate="2016-11-21T09:12:57.177" LastActivityDate="2016-11-21T09:12:57.177" Title="What are good resources for learning more about communications?" Tags="&lt;radio-communications&gt;&lt;phraseology&gt;&lt;literature-recommendation&gt;" AnswerCount="2" CommentCount="11" ClosedDate="2019-09-09T11:17:27.633" ContentLicense="CC BY-SA 3.0" />
  <row Id="19055" PostTypeId="2" ParentId="19053" CreationDate="2015-08-18T21:37:05.107" Score="-2" Body="&lt;p&gt;&lt;a href=&quot;http://www.westwingsinc.com/vfrcomm.pdf&quot; rel=&quot;nofollow&quot;&gt;VFR Communications for Idiots (West Wings)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radio Mastery for VFR Pilots Workbook (book)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/libview_normal.aspx?id=17272&quot; rel=&quot;nofollow&quot;&gt;FAA safety circular on phraseology&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA holds regular safety seminars on communication&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/115.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO Standard Phraseology&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.atac.ca/web/images/Documents/Phraseology%20Guide%20for%20GA%20Pilot%20in%20Europe.pdf&quot; rel=&quot;nofollow&quot;&gt;Phraseology Guide for GA Pilots in Europe&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-18T21:37:05.107" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19058" PostTypeId="1" AcceptedAnswerId="19059" CreationDate="2015-08-18T22:50:58.537" Score="2" ViewCount="2093" Body="&lt;p&gt;Consider the following hypothetical scenario: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An MQ-1 Predator pilot sees an Su-27 closing in from straight ahead for a kill. &lt;strike&gt;The pilot prepares to write up his 10th loss of the week when he has an idea:&lt;/strike&gt; He targets the Su-27 with the laser designator and fires two &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-114_Hellfire&quot; rel=&quot;nofollow noreferrer&quot;&gt;AGM-114 Hellfire&lt;/a&gt; missiles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would this work? Can Hellfire missiles be used effectively as air-to-air weapons?&lt;/p&gt;&#xA;" OwnerUserId="9852" LastEditorUserId="15311" LastEditDate="2018-06-10T13:02:41.710" LastActivityDate="2018-06-10T13:03:00.850" Title="Can Hellfire missiles be used effectively as air-to-air weapons?" Tags="&lt;military&gt;&lt;missiles&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2015-08-19T04:21:22.090" ContentLicense="CC BY-SA 4.0" />
  <row Id="19059" PostTypeId="2" ParentId="19058" CreationDate="2015-08-18T23:08:12.730" Score="3" Body="&lt;p&gt;While I can't say that I know the too much about Hellfires, the aiming capability appears &lt;em&gt;extremely&lt;/em&gt; limited for any air-to-air combat.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The range is bad: ~8km (compared to ~35km for a 'proper' Sidewinder). Covering this does not take many seconds for jets travelling in opposite directions. I'd imagine you might be able to get a helicopter if you're lucky.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I'm incredibly doubtful that a sensible lock on any aircraft could be achieved from a Predator. Bear in mind that you only have a camera on the bottom, so you've got huge blind spots.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You got a fair bit of satellite/communication lag, in the range of 0.5 seconds either way to get any response. More likely that your opponent has already got you by the time you understand what's going on.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The majority of the Hellfire missiles appear to require a constant lock to seek its target; some can continue on autopilot with limitations if it were to lose it. Again, sustaining a lock with that setup does not have a good outlook.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Remember that the Su-27 has countermeasures (such as flares) to protect itself.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="15311" LastEditDate="2018-06-10T13:03:00.850" LastActivityDate="2018-06-10T13:03:00.850" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="19060" PostTypeId="2" ParentId="19058" CreationDate="2015-08-18T23:15:35.120" Score="3" Body="&lt;p&gt;Actually, hellfire missiles have been used as air-to-air missiles, albeit only once. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On 24 May 2001, an IDAF AH-64 Apache used two hellfire missiles to &lt;a href=&quot;http://edition.cnn.com/2001/WORLD/meast/05/24/israel.plane.02/index.html?_s=PM:WORLD&quot; rel=&quot;nofollow&quot;&gt;shoot down&lt;/a&gt; a Lebanese Cessna 152. This is the only known use of hellfire missile so far as an air-to-air missile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is doubtful if the missile could be employed against a extremely maneuverable target like the Su-27. The AGM 114 is basically a anti-tank missile and not suited for use against aerial targets. The Cessna 152 was piloted by a student pilot and in any case had little maneuverability.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue is that the laser designator has to continuously point at the aircraft through out the guidance phase, which is very difficult in the case of a predator against any fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the range is poor. All in all, unless the pilot is extremely lucky, a predator is not going to get a Su-27. Maybe a helicopter from its blind spot though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-18T23:15:35.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19061" PostTypeId="1" CreationDate="2015-08-18T23:28:37.267" Score="10" ViewCount="383" Body="&lt;p&gt;In the UK, are any certifications or particular checks legally required for a retired aircraft to perform fast taxi runs (only)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it still be possible to do them if the main wing spars have been cut and shut, for transportation purposes (no ferry flight)?&lt;/p&gt;&#xA;" OwnerUserId="9855" LastEditorUserId="1696" LastEditDate="2016-07-05T15:05:36.420" LastActivityDate="2016-09-07T16:45:48.740" Title="What are the requirements for an aircraft to be allowed to perform fast taxi runs?" Tags="&lt;aircraft-certification&gt;&lt;taxiing&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="19062" PostTypeId="2" ParentId="19047" CreationDate="2015-08-18T23:43:12.023" Score="5" Body="&lt;p&gt;Zero 'g' aircraft are basically commercial aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, it is mainly the fluid systems like the fuel and hydraulic systems in the aircraft which are affected by the zero gravity conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of jet engines, the fuel is transferred by pumps operating under pressure and the fuel injection is also under pressure in the combustion chamber. Consequently, the engine fuel system does not need any modification. In a few aircraft, the fuel tanks themselves are pressurized (like C-5) but this is for safety and wouldn't affect operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine oil and lubrication system is also usually pressurized and can operate briefly under reduced gravity conditions.&#xA;&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660014262.pdf&quot; rel=&quot;nofollow&quot;&gt;Work done by NASA&lt;/a&gt; indicates that aircraft can be used in zero gravity conditions without any major modifications to systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The zero 'g' aircraft don't operate in weightless environment for more than 20-30 seconds and the engine systems should be able to cope during that time. The main concern appears to be the training levels of the pilot.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5665" LastEditDate="2015-08-19T08:07:14.317" LastActivityDate="2015-08-19T08:07:14.317" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19063" PostTypeId="2" ParentId="18762" CreationDate="2015-08-18T23:49:20.690" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.cbp.gov/travel&quot; rel=&quot;nofollow&quot;&gt;CBP&lt;/a&gt; has a lot of programs. Government programs are confusing. Regarding the two you mention...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Global Entry basically expedites the Customs process for pre-approved travelers, making use of an automated kiosk. The service is available at &lt;a href=&quot;http://www.cbp.gov/travel/trusted-traveler-programs/global-entry/locations&quot; rel=&quot;nofollow&quot;&gt;approved locations&lt;/a&gt;, generally major aiports. &lt;strike&gt;Clearly&lt;/strike&gt;Normally, this program is meant for the commercial traveler. However, large international GA destinations can have this service as well. Example: FLL, one of the nation's busiest international GA airports. &lt;a href=&quot;http://www.cbp.gov/travel/international-visitors/travel-tourism/fort-lauderdale-hollywood-international-airport-fll&quot; rel=&quot;nofollow&quot;&gt;They have a global entry kiosk at their GA facility&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cbp.gov/travel/pleasure-boats-private-flyers&quot; rel=&quot;nofollow&quot;&gt;Preclearance&lt;/a&gt; means that traveler processing/aircraft inspection are handled &lt;em&gt;before&lt;/em&gt; the flight, rather than upon arrival in the US. But, this isn't very widespread yet. &lt;em&gt;Private aircraft&lt;/em&gt; preclearance processing is only available at Shannon, Ireland and Oranjestad, Aruba. And the list of airports you can fly to, from what I have seen, is smaller than the list of Ports of Entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So no, neither of these programs really helps you out as a Canada/US travelling GA pilot. They aren't for small airports. You have to deal with &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/us_restrictions/airspace/#entry&quot; rel=&quot;nofollow&quot;&gt;Customs, APIS, and Ports of Entry&lt;/a&gt;, and &lt;a href=&quot;https://www.eapisfile.com/Docs/eAPIS/private_flyers_guide.pdf&quot; rel=&quot;nofollow&quot;&gt;everything else&lt;/a&gt; :)&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-08-20T02:06:37.183" LastActivityDate="2015-08-20T02:06:37.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19064" PostTypeId="1" AcceptedAnswerId="19067" CreationDate="2015-08-19T00:17:15.000" Score="4" ViewCount="617" Body="&lt;p&gt;So we are flying on a reservation that flies from LAX to NRT with United then from NRT to BKK on Thai Airways via a United codeshare. This reservation was booked through United's website. When the reservation was confirmed, I noticed that the E-Ticket number was the same for all segments of the flight, across both United and Thai. Is there any central computer system used by airlines that keeps track of information such as these E-Ticket numbers to prevent discrepancies during ticketing? I ask this because I am very curious how exactly each airline's computer system &quot;talks&quot; to each other and if there is some sort of established protocol for doing so.&lt;/p&gt;&#xA;" OwnerUserId="7373" LastActivityDate="2015-08-19T17:31:00.333" Title="Is there a central database for all airline reservation information?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;codeshare&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-08-19T23:34:33.270" ContentLicense="CC BY-SA 3.0" />
  <row Id="19065" PostTypeId="1" CreationDate="2015-08-19T01:04:10.603" Score="4" ViewCount="175" Body="&lt;p&gt;We are considering a project related to drones and in my discussions with people I heard that flying UAVs overhead people (crowds or otherwise) is banned. I also heard this is the case for the USA and EU. I searched and couldn't find the related detailed explanations anywhere. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would be grateful if somebody could shed some light and point me in the right direction.&lt;/p&gt;&#xA;" OwnerUserId="9856" LastEditorUserId="62" LastEditDate="2015-08-19T01:24:20.253" LastActivityDate="2015-08-19T07:57:12.817" Title="What are the regulations on flying UAVs over people on the ground?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19066" PostTypeId="2" ParentId="16461" CreationDate="2015-08-19T01:57:10.403" Score="4" Body="&lt;p&gt;I saw this shockwave and the shockwave shadowgram a few days ago on a flight from JFK to SFO over a grey wing, and managed to &lt;a href=&quot;https://youtu.be/0gOOgrniZWE&quot;&gt;film it with my iPhone&lt;/a&gt;. If I understand it correctly it is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;the shadowgram of the shockwave on the surface of the wing (see how it moves around) &lt;/li&gt;&#xA;&lt;li&gt;later in the video you can see the shockwave itself as looking through the shockwave it distorts the front of the wing (the distortion moves as well, I think depending on where the iPhone focuses). &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9857" LastEditorUserId="1467" LastEditDate="2015-08-19T06:11:51.213" LastActivityDate="2015-08-19T06:11:51.213" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19067" PostTypeId="2" ParentId="19064" CreationDate="2015-08-19T02:34:47.220" Score="5" Body="&lt;p&gt;The simplest answer is that United and Thai have a codeshare arrangement, so United booked a ticket on all 4 segments using its own reservation system. United's reservation system communicated with Thai's to reserve your place, and the ticket was issued by United. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;that being said, there are a number of GDSs (Global Distribution Systems), which are multi-airline reservation systems, all of which communicate with each other. &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Computer_reservations_system&quot; rel=&quot;nofollow&quot;&gt;Complete information on GDSs can be found in Wikipedia. &lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="5568" LastEditDate="2015-08-19T17:31:00.333" LastActivityDate="2015-08-19T17:31:00.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19068" PostTypeId="2" ParentId="19039" CreationDate="2015-08-19T03:49:42.020" Score="4" Body="&lt;p&gt;No, the moment consciousness is lost, the body will go limp and the hands will release the controls and the aircraft will naturally seek 1g flight.  However, several cases exist where pilots have awoke in a supersonic, or near supersonic, dive and sustained massive flail injuries after ejecting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its also important to note that simply jumping in the air will exert your body to instantaneous G-forces well above what you'd experience in a fighter aircraft.  If such G-forces were capable of causing injury then you'd hardly be able to get out of bed without causing grievous injury.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The danger to high G-forces in the vertical axis is that the blood is pulled from the brain to the lower extremities causing a form of hypoxia commonly referred to as GLOC, or G Induced Loss of Consciousness.  For what it's worth, skeletal injuries due to G forces are so rare that they aren't even briefed during training.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-08-19T03:55:38.817" LastActivityDate="2015-08-19T03:55:38.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19070" PostTypeId="2" ParentId="19065" CreationDate="2015-08-19T07:57:12.817" Score="2" Body="&lt;p&gt;The general rule of thumb is &quot;don't do anything hazardous for people or property on the ground&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, &lt;a href=&quot;http://knowbeforeyoufly.org/for-recreational-users/&quot; rel=&quot;nofollow&quot;&gt;do not intentionally fly over unprotected persons or moving vehicles, and remain at least 25 feet away from individuals and vulnerable property&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on whether your project is for recreation or not, how heavy the drone is,... you may not be able to do the same things. The FAA website has a page titled ``&lt;a href=&quot;https://www.faa.gov/uas/what_can_you_do_with_your_uas/&quot; rel=&quot;nofollow&quot;&gt;What Can You Do With Your Unmanned Aircraft?&lt;/a&gt;'' that gives details on what you can and can't do based on these parameters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.easa.europa.eu/system/files/dfu/204696_EASA_concept_drone_brochure_web.pdf#5&quot; rel=&quot;nofollow&quot;&gt;A document published by EASA&lt;/a&gt; states that for low-risk drone operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flights above crowds are prohibited, but flights above people not related to the operation in cities or populated areas is allowed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Refer also to local laws. A number of states and municipalities have passed or are considering limitations on unmanned aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-08-19T07:57:12.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19072" PostTypeId="2" ParentId="17672" CreationDate="2015-08-19T09:53:36.310" Score="7" Body="&lt;p&gt;This answer is a bit of a guess. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this design choice helps the pilot in manually flying in the coffin corner. By ensuring that the direction of movement of the horizon, altitude and speed tape all require the same stick input, less mental workload is needed to fly the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the nose of the aircraft is lowered:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The artificial horizon will move &lt;strong&gt;up&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;The altitude will decrease, hence the altitude tape moves &lt;strong&gt;up&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;The speed will increase, hence the speed tape moves &lt;strong&gt;up&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Any visual clue from the display that involves an upward optical flow can be corrected by pulling the stick. This consistent behaviour reduces the mental workload. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-08-19T09:53:36.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19073" PostTypeId="1" AcceptedAnswerId="19079" CreationDate="2015-08-19T10:03:22.377" Score="11" ViewCount="27072" Body="&lt;p&gt;The wing tips are very different on these airplanes. The wingtip on a Boeing 787 is a sharp triangle, while the wingtip on a Boeing 737-300 is flat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wmEhr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wmEhr.jpg&quot; alt=&quot;British Airways Boeing 787-8 G-ZBJC wingtip | by StephenG88&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;British Airways Boeing 787-8 G-ZBJC wingtip | by StephenG88 (&lt;a href=&quot;https://c3.staticflickr.com/3/2851/10026361263_d67f62b145_b.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is the wingtip on the Boeing 787 different from that of the Boeing 737?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1961" LastEditDate="2015-08-19T11:31:10.017" LastActivityDate="2017-11-08T15:19:27.627" Title="How does the raked wingtip of the Boeing 787 work?" Tags="&lt;airliner&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19074" PostTypeId="1" AcceptedAnswerId="19075" CreationDate="2015-08-19T10:14:28.997" Score="3" ViewCount="1345" Body="&lt;p&gt;There is a small plate sticking out of an A320's engine narcelle with &quot;No Step&quot; written on it. I tried taking a picture of it, which in retrospect didn't turn out as good as I wanted it to be, but I hope it helps:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qXEAX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qXEAX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, I'm wondering what it's used for? It's only on one side towards the aircrafts body and it seems to be too small to be an aerodynamic surface. I suspect it's used during maintenance?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastActivityDate="2015-08-19T10:26:51.443" Title="What is the &quot;No Step&quot; flap thingy used for on an A320 engine?" Tags="&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-19T11:13:54.587" ContentLicense="CC BY-SA 3.0" />
  <row Id="19075" PostTypeId="2" ParentId="19074" CreationDate="2015-08-19T10:26:51.443" Score="4" Body="&lt;p&gt;It's a vortex generator explained in full in &lt;a href=&quot;https://aviation.stackexchange.com/q/13876/609&quot;&gt;this question&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;NO STEP&quot; means don't put your foot on it. It's too weak to hold a person's weight and would get damaged.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-19T10:26:51.443" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19077" PostTypeId="2" ParentId="8272" CreationDate="2015-08-19T11:34:02.730" Score="3" Body="&lt;p&gt;Under Visual Flight Rules (VFR) &quot;See and Avoid&quot; is used. For every 9 seconds spent looking out of the cockpit scanning the sky for other aircraft, the pilot spends 1 second inside the cockpit checking instruments etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An important part of this though is that if the aircraft is equipped with radio then the pilot should talk to an air traffic service, even a procedural service like London Information is useful, because a) the information service will tell the pilot of other known movements in his area and b) by giving out PACER (position, altitude, conditions, estimate request) reports, other VFR aircraft will be able to listen and if necessary change their own altitude in advance if there is any doubt about seeing the other aircraft in time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all VFR aircraft have radios though. There are additional rules like not flying too close to clouds. I believe one reason is that you don't want another aircraft to appear out of a cloud just feet away. Ultimately though, its the MK1 eyeball and the owner of that eyeballs responsibility not to run into other aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-19T11:34:02.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19078" PostTypeId="2" ParentId="19073" CreationDate="2015-08-19T12:07:51.123" Score="19" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device#Raked_wingtip&quot; rel=&quot;noreferrer&quot;&gt;raked wingtip&lt;/a&gt; of the Boeing 787 is now &quot;le denier cri&quot; in wingtip design, but has been &lt;a href=&quot;https://aviation.stackexchange.com/questions/8544/is-wingtip-design-mature/8554?s=1%7C0.0677#8554&quot;&gt;successfully employed by water fowl&lt;/a&gt; for many millennia. The use of composite structures has made the three-dimensional shaping of wingtips much easier, and the first airplanes to use increased sweep at the wingtip were indeed composite gliders such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Discus&quot; rel=&quot;noreferrer&quot;&gt;Schempp-Hirth Discus&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wd8Js.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wd8Js.jpg&quot; alt=&quot;Seagull (left) Schempp-Hirth Discus 2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seagull (left) Schempp-Hirth Discus 2 (right, &lt;a href=&quot;http://www.sailplanedirectory.com/images/discus2.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the times of metal wings, &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Flugzeugwerke&quot; rel=&quot;noreferrer&quot;&gt;Dornier&lt;/a&gt; introduced their TNT (Tragflügel Neuer Technologie, in English: Wing of new technology) on aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_228&quot; rel=&quot;noreferrer&quot;&gt;Do 228&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_328&quot; rel=&quot;noreferrer&quot;&gt;Do 328&lt;/a&gt; and the &lt;a href=&quot;http://www.do-24.com/index.php?home&quot; rel=&quot;noreferrer&quot;&gt;Dornier ATT&lt;/a&gt; flying boat. It used a triangular wingtip with no change in trailing edge sweep, which is easier to manufacture in aluminium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r1GIf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r1GIf.jpg&quot; alt=&quot;An Air Alps Dornier 328-110 landing at Fiumicino Airport, Rome, Italy, viewed from Ostia Antica&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An Air Alps Dornier 328-110 landing at Fiumicino Airport, Rome, Italy, viewed from Ostia Antica. Picture by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Makaristos&quot; rel=&quot;noreferrer&quot;&gt;Makaristos&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can think of the raked wingtip as of a winglet which has been folded down. Increasing the wingspan will involve a bigger mass of air into the creation of lift, and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579?s=6%7C0.0850#8579&quot;&gt;induced drag is reduced&lt;/a&gt;. This explains already most of the effect, but the increased sweep adds some more benefits.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Higher sweep lowers the lift curve slope. This helps to reduce the lift contribution (and, consequently, the bending moment!) of the wingtip at high angles of attack. Therefore, raking the wingtip will result in a lower maximum bending moment.&lt;/li&gt;&#xA;&lt;li&gt;The sweep also shifts the center of pressure of the wingtip backwards, adding a negative torsion moment. This moment lowers the angle of attack over the whole outer wing in gusts and at high load factors, again helping to lower the maximum bending moment at the root.&lt;/li&gt;&#xA;&lt;li&gt;Especially in gliders, it allows to combine a near-elliptical circulation distribution over a wide range of angles of attack with good stall characteristics. The lower lift curve slope of the wingtip lets it stall at a higher angle of attack and reduces its lift contribution relative to its area at increasing angle of attack.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=20140006404&quot; rel=&quot;noreferrer&quot;&gt;aeroelastic tailoring&lt;/a&gt;, together with the low fuel consumption of modern &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;noreferrer&quot;&gt;high-bypass-ratio engines&lt;/a&gt;, allows the Boeing 787 to use a wing of an aspect ratio of 11. Previously, - apart from gliders - only special designs for extreme flying time and range like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_B-24_Liberator&quot; rel=&quot;noreferrer&quot;&gt;B-24 Liberator&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Breguet_Atlantic&quot; rel=&quot;noreferrer&quot;&gt;Breguet Atlantique&lt;/a&gt; sported such high aspect ratios. Older airliner designs &lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing/8797?s=6%7C0.1981#8797&quot;&gt;had to use lower aspect ratios&lt;/a&gt; (between 6 and 8.5) to have enough wing volume for fuel.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-22T20:05:09.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19079" PostTypeId="2" ParentId="19073" CreationDate="2015-08-19T12:17:00.713" Score="10" Body="&lt;p&gt;The purpose of the raked wingtip is same as that of the winglet- to reduce drag by reducing the effect of the wingtip vortices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/L7AW3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/L7AW3.jpg&quot; alt=&quot;Boeing 767-600 Raked Wingtip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.boeing.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircrafts use winglets to improve performance. Basically, they reduce the wingtip vortex by [deflecting the air](and the associated drag by deflecting the air that wants to escape over the tip back down) that wants to escape over the tip back down. This reduces the induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of raked wingtips, the tips of the wings have more sweep compared to the rest of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IR5DY.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IR5DY.png&quot; alt=&quot;Boeing 787 with raked wingtips&quot;&gt;&lt;/a&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:B787-800v1.0.png#/media/File:B787-800v1.0.png&quot; rel=&quot;noreferrer&quot;&gt;B787-800v1.0&lt;/a&gt;&quot; by Julien.scavini - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The raked wingtips also reduce the wingtip  vortex- by redirecting the wingtip vortices further &lt;em&gt;outboard and aft&lt;/em&gt; of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The raked wingtips are more efficient compared to the winglets in cruise and are used in ultra long range aircrafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0WtQs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0WtQs.jpg&quot; alt=&quot;Comparison of drag reduction due to wingtip devices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.boeing.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One problem with the raked wingtips is that they increase the span. This increases the bending moment. Another reason we are not seeing a number of aircrafts with raked wingtips is due to the fact that they can't be retrofitted (Though there was a proposal to retrofit KC135 with raked wingtips).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The photo is not very clear. I'd simply answered about the raked wingtip.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-19T12:17:00.713" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="19081" PostTypeId="1" AcceptedAnswerId="19084" CreationDate="2015-08-19T12:25:39.427" Score="5" ViewCount="4249" Body="&lt;p&gt;In the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/19016/could-airliners-wings-be-thinner-if-no-fuel-were-stored-in-them&quot;&gt;this question&lt;/a&gt; about wing thickness, there were many references to wing thickness as a percentage (ranging from 6.5% to 13.5%).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that a percentage &lt;em&gt;of&lt;/em&gt;?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-19T12:34:14.187" Title="How is &quot;wing thickness&quot; defined?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19082" PostTypeId="2" ParentId="19081" CreationDate="2015-08-19T12:30:01.453" Score="6" Body="&lt;p&gt;From the image in the answer you link to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;thickness in percent of chord&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and the chord (length) is the distance between leading edge and trailing edge of the airfoil of the wing.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-08-19T12:30:01.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19083" PostTypeId="2" ParentId="19053" CreationDate="2015-08-19T12:34:02.883" Score="5" Body="&lt;p&gt;Phraseology is standardized by the ICAO (but countries can notify differences to the standard) in Annex 10 and other documents. The &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/115.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO quick reference guide&lt;/a&gt; presents phraseology examples for various situations (taxi, approach, emergency,...). If you are interested in recommendations concerning radio communications in general (not just what directly concerns the pilot), Eurocontrol released a &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/news/content/documents/nm/safety/agc-action-plan.pdf&quot; rel=&quot;nofollow&quot;&gt;European Action Plan for Air Ground Communications Safety&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many CAAs also have some form of phraseology reference manual available for free. The general procedures and the phraseology will be almost the same from one country to the next, but variations do occur. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;US: &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The AIM has &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf#197&quot; rel=&quot;nofollow&quot;&gt;a section dedicated to radio communications&lt;/a&gt; which details procedures, phraseology and provides general recommendations. Communication examples illustrate the general principles. &lt;/li&gt;&#xA;&lt;li&gt;The FAA also published an &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/atc.pdf&quot; rel=&quot;nofollow&quot;&gt;order prescribing ATC procedures and phraseology&lt;/a&gt; (but this is a very dry read. Not where I would start)&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/FAA-H-8083-16.pdf&quot; rel=&quot;nofollow&quot;&gt;Instrument Procedures Handbook&lt;/a&gt; contains information regarding radio communication procedures specific to instrument flying (e.g. how to receive a clearance at a non-towered airport)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;EU:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Eurocontrol released &lt;a href=&quot;http://www.atac.ca/web/images/Documents/Phraseology%20Guide%20for%20GA%20Pilot%20in%20Europe.pdf&quot; rel=&quot;nofollow&quot;&gt;a guide to phraseology for GA pilots&lt;/a&gt; describing good communication practices, phraseology for different flight phases and aviation acronyms. It also has pictures (picture books are always better ;-) ).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;UK:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The CAA release &lt;a href=&quot;http://www.caa.co.uk/docs/33/CAP41320Editionto4April2013_ISBN9780117928206.pdf&quot; rel=&quot;nofollow&quot;&gt;a radiotelephony manual&lt;/a&gt; describing the phraseology for different flight phases with examples at the end of the manual. It also describes the differences between ICAO and UK radiocommunications procedures (eg FL ONE HUNDRED instead of FL ONE ZERO ZERO). &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;France:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The SIA has a &lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/asp_ssl/texteregle/texteregle-b.asp?ordre_0=3&amp;amp;langu=fr&quot; rel=&quot;nofollow&quot;&gt;phraseology training manual&lt;/a&gt; with phraseology examples for each flight phase and for using different flight services (ATC, AFIS,...)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.sia.aviation-civile.gouv.fr/dossier/texteregle/RADIOTEL_V2.pdf&quot; rel=&quot;nofollow&quot;&gt;The official text for radiotelephony&lt;/a&gt; with phraseology in French and English&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;And many more...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Knowing the phraseology is one thing, but understanding what is being said on the radio can be quite difficult. If you want to practice listening to and understanding radio exchanges, you can find ATC recordings on &lt;a href=&quot;http://www.youtube.com&quot; rel=&quot;nofollow&quot;&gt;YouTube&lt;/a&gt; or go to &lt;a href=&quot;http://www.liveatc.net&quot; rel=&quot;nofollow&quot;&gt;LiveATC&lt;/a&gt; for ATC communications from all over the world.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2015-08-19T12:42:34.300" LastActivityDate="2015-08-19T12:42:34.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19084" PostTypeId="2" ParentId="19081" CreationDate="2015-08-19T12:34:14.187" Score="9" Body="&lt;p&gt;The wing thickness is basically the distance between the upper and lower surface of the wing (or airfoil).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;`&lt;a href=&quot;https://i.stack.imgur.com/98s3Y.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/98s3Y.gif&quot; alt=&quot;Airfoil geometry&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: NASA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing thickness is usually given as a percentage of the wing (or airfoil) chord(the distance between the leading and trailing edge). This is to make it a non-dimensional quantity for ease of comparison across different scales. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-19T12:34:14.187" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19085" PostTypeId="2" ParentId="8272" CreationDate="2015-08-19T13:04:47.460" Score="0" Body="&lt;p&gt;I am also a glider pilot. The Soaring Society of America (SSA) recently published a &lt;a href=&quot;http://www.ssa.org/GeneralNews?show=blog&amp;amp;id=4035&quot; rel=&quot;nofollow&quot;&gt;rather lengthy letter&lt;/a&gt; on collision avoidance, particularly concerning gliders and powered aircraft, in response to the FAA Advance Notice of Proposed Rulemaking.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First and foremost, midair collisions in general are unlikely, due to the vast amount of space available to maneuver vs the relatively small size of (even large) aircraft.  That being said, due to conventions and limitations near airports and air routes, along with the sheer number of aircraft, collision avoidance does become an important concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For gliders, collision avoidance is particularly important because they tend to be restricted in geographic range due to atmospheric or geographic features. The SSA letter particularly references how this is an issue around the space between Las Vegas and Minden, due to the ridge and wave lift available in that area. I have similar experience flying in the ridge due east of the Washington, DC metropolitan area, which also has a heavy amount of commercial jet traffic inbound to the region's three major airports.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some snippets from the SSA's letter which I believe are relevant:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;SSA agrees that expanded use of available forms of anti-collision&#xA;  technology in flying machines of all types – not just in gliders –&#xA;  obviously would make flying safer.  Thus, a large number of US glider&#xA;  pilots have voluntarily added to their cockpits either transponders&#xA;  (which broadcast the position of a glider to ATC and TCAS equipped&#xA;  traffic) or an alternative, effective, lower-cost technology called&#xA;  FLARM (which, in addition to broadcasting location information, also&#xA;  provides collision alert data in the cockpit of gliders, much as TCAS&#xA;  does in the cockpit of larger, more expensive aircraft.) FLARM has&#xA;  been widely accepted worldwide and has the support of the European&#xA;  Aviation Safety Agency (EASA.)  It is so successful and effective that&#xA;  the use of FLARM (rather than transponders) is now mandated for&#xA;  gliders flying in French airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to SSA's research, FLARM is more effective than transponders, because transponders require active involvement from the FAA controllers, and controllers typically clear VFR aircraft (which includes gliders) from their screens. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Transponders are not true collision avoidance devices in that they do&#xA;  not provide any direct information to the pilot.  They may be useful&#xA;  to other pilots who are equipped with a TCAS (or similar) device, but&#xA;  because of very high costs those devices are not in widespread use&#xA;  except by the highest end of the aviation community.  As an additional&#xA;  issue, when air traffic controllers have too many targets on their&#xA;  displays, they may suppress VFR traffic, which would include&#xA;  transponder equipped gliders.  And as a matter of policy, ATC does not&#xA;  necessarily give IFR traffic advisories on uncontrolled VFR traffic in&#xA;  its vicinity even if that traffic is transponder equipped.  (Gliders&#xA;  rarely operate under positive ATC control and are therefore generally&#xA;  “uncontrolled” even when operating a transponder).  Aircraft that fly&#xA;  VFR only and are not in contact with ATC derive essentially no direct&#xA;  safety benefit from equipping with a transponder; doing so only&#xA;  assists ATC in applicable areas and the high end users of the NAS that&#xA;  are equipped with expensive collision avoidance devices like TCAS; or&#xA;  in the case of gliders, with PowerFlarm.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...    &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each FLARM device determines its position and altitude with a highly&#xA;  sensitive state of the art GPS receiver. Based on speed, acceleration,&#xA;  heading, track, turn radius, wind, altitude, vertical speed,&#xA;  configured aircraft type, and other parameters, a very precise&#xA;  projected flight path can be calculated. The flight path is encoded&#xA;  and sent over an encrypted radio channel to all nearby aircraft at&#xA;  least once per second.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;At the same time, the FLARM device receives the same encoded flight&#xA;  path from all surrounding aircraft. Using a combination of own and&#xA;  received flight paths, an intelligent motion prediction algorithm&#xA;  calculates a collision risk for each received aircraft based on an&#xA;  integrated risk model. The FLARM device communicates this, together&#xA;  with the direction and altitude difference to the intruding aircraft,&#xA;  to the connected FLARM display. The pilots are then given visual and&#xA;  aural warnings and can take resolutive action.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Read more from the SSA Letter&lt;/strong&gt; &lt;a href=&quot;http://www.ssa.org/GeneralNews?show=blog&amp;amp;id=4035&quot; rel=&quot;nofollow&quot;&gt;http://www.ssa.org/GeneralNews?show=blog&amp;amp;id=4035&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="809" LastActivityDate="2015-08-19T13:04:47.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19086" PostTypeId="2" ParentId="16862" CreationDate="2015-08-19T14:43:28.330" Score="4" Body="&lt;p&gt;As well as the advances in engineering, it is worth considering the comfort of the passengers. It is often thought that the more natural light in the cabin the better the experience for the passengers. More light increases the feeling of space, and can even reduce the fatigue experienced as a result of air travel. Whether or not there is much science in this I do not know.&lt;/p&gt;&#xA;&lt;p&gt;Some Aircraft manufacturers use the window sizes as a big selling point. Gulfstream aircraft, for example, allow in more light than any comparable aircraft due to their oval shaped windows. In an attempt to compete Dassault are putting more windows on their newer Falcon 8x and Falcon 5x models.&lt;/p&gt;&#xA;&lt;p&gt;Both companies have also introduced windows in the galleys in some models (Dassault famously with the 'sky light') as this is  typically the darkest and narrowest part of the cabin. In the cabin configurations most typical in Europe, the galley is at the very front of the cabin and is the first thing you see when you enter the aircraft. I think it is safe to say that it is much nicer to walk into a bright, airy space than a dark, narrow corridor.&lt;/p&gt;&#xA;&lt;p&gt;Gulfstream 650 window details:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Sixteen large Gulfstream panoramic windows, each 28 by 20.5 inches/71&#xA;by 52 centimeters, allow abundant sunlight into the cabin, even in the&#xA;galley. Every window has been repositioned higher on the fuselage to&#xA;maximize viewing comfort*&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gulfstream.com/aircraft/gulfstream-g650&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.gulfstream.com/aircraft/gulfstream-g650&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Falcon 5X window &amp;amp; 'skylight' details:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Increased natural light does more than improve the view. It elevates&#xA;your mood and enlarges your perspective. The 28 large, expansive&#xA;windows of the 5X provide unbeatable luminosity.&lt;/p&gt;&#xA;&lt;p&gt;The Falcon 5X offers an unprecedented direct view of the sky overhead&#xA;through its skylight ceiling window. This unique window on the sky&#xA;transforms your perception of space while providing natural light from&#xA;above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dassaultfalcon.com/en/Aircraft/Models/5X/Pages/overview.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.dassaultfalcon.com/en/Aircraft/Models/5X/Pages/overview.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9867" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-19T14:43:28.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19087" PostTypeId="1" AcceptedAnswerId="19091" CreationDate="2015-08-19T14:57:13.677" Score="7" ViewCount="451" Body="&lt;p&gt;From what I learn, in large towered airports, the control of who enters and leaves the runways belong to the Control Tower Operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is there any Equipment or System in large airports to warn the tower of something/someone entered or is crossing the runway? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastActivityDate="2018-10-25T17:56:58.780" Title="Is there any System to warn of Runway Incusion?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19088" PostTypeId="1" CreationDate="2015-08-19T15:01:22.027" Score="8" ViewCount="149" Body="&lt;p&gt;What are typical insurance costs for airliners, and how are they arrived at? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Factors that might be relevant are hours flown, number of landings/takeoffs per year, total hours of airframe and engines, hours on type for the pilot in command, etc. - but are they considered, and how?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, are long-haul flights treated differently than short-haul?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, each specific contract is covered by commercial confidentiality, but some baseline estimates should be available somewhere.&lt;/p&gt;&#xA;" OwnerUserId="2176" LastActivityDate="2015-09-18T01:17:55.503" Title="What are typical insurance costs for airliners?" Tags="&lt;insurance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19089" PostTypeId="1" AcceptedAnswerId="19092" CreationDate="2015-08-19T15:28:45.127" Score="5" ViewCount="522" Body="&lt;p&gt;The 787 uses a variety of sound reducing mechanism including engines with characteristic chevrons:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7cGEr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7cGEr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(Source wikimedia commons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be possible for older airplanes to also have this type of quieter engine retrofitted? I'm assuming the engines would have to be recertified of course. &lt;strong&gt;But do the chevrons implicate a particular type of wing or airframe that requires them to be designed in from the beginning?&lt;/strong&gt; &lt;/p&gt;&#xA;" OwnerUserId="2407" LastActivityDate="2016-12-13T18:15:06.730" Title="Could older airplanes be retrofitted with engines with chevrons?" Tags="&lt;engine&gt;&lt;noise&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19090" PostTypeId="2" ParentId="19089" CreationDate="2015-08-19T15:37:07.670" Score="3" Body="&lt;p&gt;Yes. This kind of engine design is independent of the wing and airframe and can be fitted on compatible aircrafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, General Electric &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;nofollow&quot;&gt;GEnx-1B64&lt;/a&gt;, an engine with chevrons is fitted on Boeing 747-8, a variant of Boeing 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the engines (especially civil airliner engines) are developed with compatibility in mind to reduce costs and increase commonality.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-08-19T15:42:46.180" LastActivityDate="2015-08-19T15:42:46.180" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19091" PostTypeId="2" ParentId="19087" CreationDate="2015-08-19T15:46:44.483" Score="16" Body="&lt;p&gt;Yes, there are several systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest are REALLY BIG WINDOWS (and binoculars):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/fZ1kv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fZ1kv.jpg&quot; alt=&quot;ATCT - Interior/Windows&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;When the entire wall in front of you is a big expanse of glass looking out over the runway there's a good chance you'll notice something trying to roll onto the runway.&lt;br&gt;&#xA;Many runway incursions are detected visually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Really big windows don't work as well when you have multiple runways and larger airport complexes though, so we have some technological solutions too. The most common is Automated Surface Detection Equipment (ASDE), the one being deployed today is &lt;a href=&quot;https://en.wikipedia.org/wiki/ASDE-X&quot; rel=&quot;noreferrer&quot;&gt;ASDE-X&lt;/a&gt;.&lt;br&gt;&#xA;This is basically &quot;radar on the ground&quot; which interrogates aircraft transponders and shows the controllers which aircraft are where on the airport surface:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6se6n.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6se6n.jpg&quot; alt=&quot;ASDE-X display, KORD&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are also systems on the ground designed to prevent incursions, but those are mainly for use by pilots.&lt;br&gt;&#xA;These include &lt;a href=&quot;https://www.faa.gov/air_traffic/technology/rwsl/gallery/&quot; rel=&quot;noreferrer&quot;&gt;Runway Status Lights&lt;/a&gt;, &lt;a href=&quot;http://www.skybrary.aero/index.php/Active_Ground_Lighting_Control&quot; rel=&quot;noreferrer&quot;&gt;taxiway guidance lights&lt;/a&gt; (which include &quot;stop bars&quot; that light up on hold-short lines), and &quot;runway guard lights&quot; (which may be mounted either in the pavement or &lt;a href=&quot;https://i.stack.imgur.com/mQc4n.jpg&quot; rel=&quot;noreferrer&quot;&gt;alongside the taxiway/runway intersection&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of these systems can be controlled from the tower, either by automatic systems or manually by the controllers.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="65" LastEditDate="2018-10-25T17:56:58.780" LastActivityDate="2018-10-25T17:56:58.780" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="19092" PostTypeId="2" ParentId="19089" CreationDate="2015-08-19T16:05:34.097" Score="6" Body="&lt;p&gt;The chevrons do not implicate a particular type of wing or airframe. However, the engine does need to be designed around having the chevrons, since they affect the performance as well as noise. And the engine design certainly can affect the design of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, chevrons are more likely to be incorporated in an engine design from the start rather than retrofitted later. And a new engine design will probably be for a new airplane design. This could be a totally new plane like the 787. But it could also be a new derivative, like the 747-8 or the 737 MAX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while chevrons can be added to the engines on an existing aircraft model, it's much more likely that the aircraft model will be upgraded in other ways as well to accommodate the new engines. Adding chevrons is likely to be part of a design change large enough to justify changes to the aircraft as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, these changes are not really specific to the engine having chevrons. Changes to the wing and airframe will be due to the inclusion of a new engine, not just the addition of chevrons.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-08-19T16:05:34.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19093" PostTypeId="1" AcceptedAnswerId="19094" CreationDate="2015-08-19T16:07:40.497" Score="8" ViewCount="3998" Body="&lt;p&gt;I recently saw a movie in which what appeared to be a Lockheed C-130 Hercules was suddenly without occupants. They did not move or exit the craft, they simply vanished. I assume that the craft remained pressurised, and no modifications to controls were made. I assume that any auto-pilot-like features remained either on or off as they were at the time, unless they have some kind of system to automatically engage in certain situations. At the time of the incident, the aircraft appeared to be cruising.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering how long it would take for a cruising aircraft take to crash if everyone spontaneously vanished?&lt;/p&gt;&#xA;" OwnerUserId="2335" LastActivityDate="2015-08-20T00:29:37.773" Title="How long would a cruising aircraft take to crash if everyone spontaneously vanished?" Tags="&lt;theory&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19094" PostTypeId="2" ParentId="19093" CreationDate="2015-08-19T16:31:25.403" Score="13" Body="&lt;p&gt;There is a far more important question (and the real deciding factor) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;How much fuel is on board?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If left unattended a plane will fly until it runs out of gas quite literally, the more gas in the tanks the longer you have. This has happened on occasion before. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot;&gt;Helios Airways Flight 522&lt;/a&gt; is about as close as you can get to this hypothetical situation in real life. The plane may travel farther (since its lighter) but it will go until its out of gas. The same thing applies to &lt;a href=&quot;http://www.pilotfriend.com/aeromed/medical/uncon_landing.htm&quot;&gt;smaller GA planes&lt;/a&gt; as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is all of course assuming that the plane is not intercepted before running out of gas. Helios 522 was intercepted by F-16's before it crashed and they visually established that the crew was incapacitated (although a flight attendant tried to save the plane). I don't know what the procedure is for interceptions like this but if the plane were headed for a highly populated area they may not let it run out of fuel. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-19T16:46:59.290" LastActivityDate="2015-08-19T16:46:59.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19095" PostTypeId="1" AcceptedAnswerId="19098" CreationDate="2015-08-19T16:39:21.127" Score="11" ViewCount="1435" Body="&lt;p&gt;I am a student in mechanical engineering with a passion for aerospace engineering, especially airplane design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, coming from a more mechanical than pure aeronautical background, I feel that even now, doing a masters in what is essentially conceptual airplane design, I am lacking a certain foundation in the methodology of airplane design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To remedy this I have recently obtained the very well-known books on airplane design by Roskam and Raymer and have started working through these books.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: In the modern age of airplane design, where we are starting to get interested in more novel and radical configurations, are the approaches presented by Roskam and Raymer (and I am sure there are others authors) still valid?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarise this design methodology I am talking about:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Determine payload weight    &lt;/li&gt;&#xA;  &lt;li&gt;Guess aircraft maximum takeoff weight&lt;/li&gt;&#xA;  &lt;li&gt;Estimate fuel fractions for different mission segments from historical correlations&lt;/li&gt;&#xA;  &lt;li&gt;Calculate tentative empty weight&lt;/li&gt;&#xA;  &lt;li&gt;Determine allowable empty weight by taking advantage of the fact that, historically, there is a logarithmically linear relationship between maximum takeoff weight and empty weight&lt;/li&gt;&#xA;  &lt;li&gt;Compare tentative empty weight and allowable empty weight, if the values are too different, guess a new value for maximum takeoff weight and continue this iterative process until convergence&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This design procedure uses historical correlations in the fuel fraction determination and through the historical trend in relationships between MTOW and OEW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this approach still valid for novel configurations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most importantly, is it known whether this logarithmically linear relationship between MTOW and OEW independent on configuration?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="1696" LastEditDate="2016-07-05T15:10:55.040" LastActivityDate="2016-07-05T15:10:55.040" Title="Are general relationships between MTOW and OEW valid for novel configurations?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19096" PostTypeId="2" ParentId="19093" CreationDate="2015-08-19T17:53:37.193" Score="9" Body="&lt;p&gt;If the autopilot was on, it's a question of how much fuel is on board as related in another answer (unless high ground was in the way). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the autopilot is off, even if in perfect trim, the aeroplane will usually gradually drop a wing (this process will start within 15-30 seconds) and develop an ever steepening spiral dive and crash at high speed into the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes something different has happened, perhaps if a dead pilot has his hands on the controls, but in most cases there is insufficient stability for it to remain wings level for long without pilot input. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking of an example in the States where an airliner's wing sliced through the cabin of a light aircraft and cut the three occupants into two. That aircraft managed to land itself intact in a school playing field I think it was, with blood covering the fuselage and wings, but no fuselage top and no visible occupants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, in a small plane the trim might be affected by people disappearing (due to a change in CG) but I think the usual result would be to drop a wing as related. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not aware of any systems that would turn an autopilot on automatically if it was off. Finally, many light aircraft only have wing leveller autopilots, so in this case, even if it was out of trim on the elevators, it would take longer (perhaps much longer) to crash, it just might fly long enough to run out of fuel, assuming no mountains were in the way.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="3550" LastEditDate="2015-08-19T20:10:08.947" LastActivityDate="2015-08-19T20:10:08.947" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19097" PostTypeId="1" AcceptedAnswerId="19101" CreationDate="2015-08-19T19:13:52.423" Score="3" ViewCount="3385" Body="&lt;p&gt;Montreal is not large city like Paris and New York, nor a important place in aviation history like &lt;a href=&quot;https://en.wikipedia.org/wiki/Kitty_Hawk,_North_Carolina&quot; rel=&quot;nofollow&quot;&gt;Kitty Hawk&lt;/a&gt;(Wright brothers first flight) or &lt;a href=&quot;https://en.wikipedia.org/wiki/Friedrichshafen&quot; rel=&quot;nofollow&quot;&gt;Friedrichshafen&lt;/a&gt; (Zeppelin airship first flight). Why Montreal is being chosen as the headquarters of 2 biggest aviation organization. &lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-08-19T22:04:46.040" LastActivityDate="2015-08-20T09:42:17.073" Title="Why both ICAO and IATA headquarters are located in Montreal?" Tags="&lt;icao&gt;&lt;iata&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19098" PostTypeId="2" ParentId="19095" CreationDate="2015-08-19T20:15:58.670" Score="13" Body="&lt;p&gt;Many studies and presentations you will encounter about radically different configurations with much higher performance are the aviation equivalent of car commercials. Someone tries to get attention in order to get published, or she/he needs to convince investors to fork over their money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trust me, the aircraft designers of the last century were no idiots. They had the luck of living in a time when it took only a few years for aircraft designs to become obsolete, so they could go through the whole design process many times and apply what they had learned before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone graduating from university today will be lucky if she/he gets the chance to go through every step of a major design process even once. I myself have brought three aircraft into the air and consider myself very lucky. I had colleagues who retired without ever having seen one of their many projects take off (literally).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The consequence of this is a very mature industry which has found an optimum configuration for most purposes already and is only tinkering with the details. Add to this an ever increasing thicket of regulations which have grown on the experience from existing designs. Sure, the progress in computer control is impressive, and engines get better all the time. Manufacturing precision is ever increasing, and materials still become better and more consistent. But overall, we still build aircraft like we did a generation ago, and I do not expect this to change radically in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What impacts the design process most is certainly the incredible precision of simulation software, which allows to see details which remained hidden in a wind tunnel or a strength test. Things which had to be done consecutively can now be done in parallel, and the precision of knowledge at an early stage of a design is much higher than before. But at the same time aircraft become ever more complex, so the advantage of better simulation is eaten up by the increase in complexity. Add to that the fact that mostly beancounters will have the last word, where before engineers could determine how the work was done, and you will understand that the level of preparatory work is shockingly inadequate in modern aircraft companies. Many of the avoidable early mistakes will require late, expensive fixes (but by that time the stingy beancounter has left the company with a huge bonus for the money he bragged to have saved).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design process is still the same, and where before the experience of a few people helped to find an overall optimum, large, integrated teams will together determine this optimum. The inexperience of the participants will only show up in delays, when the iterative design cycle needs to be repeated more often than anticipated, but the result will be of high quality - really bad designs are a thing of the past. But cutting corners will still have consequences, so small annoyances will still plague new designs. Consequently, most of the engineering work will involve ironing out these annoyances or retrofitting new systems to existing airframes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your specific question: Yes, the relation between OEW and MTOW will still hold in the future, and radically new configurations will show an advantage only on paper, before they have been thoroughly designed and test-flown. Better materials and methodologies will help to improve the ratio between OEW and MTOW, but this advantage risks to be eaten up by the desire to add bells and whistles everywhere.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-19T20:35:30.523" LastActivityDate="2015-08-19T20:35:30.523" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19099" PostTypeId="2" ParentId="15042" CreationDate="2015-08-19T20:43:16.843" Score="8" Body="&lt;p&gt;To get a better idea of whether this was possible I looked at the weight and balance for a 737. The &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane Characteristics document&lt;/a&gt; provides the necessary information to estimate how the center of gravity (CG) may shift due to passengers deplaning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information in the document shows between 89% and 96% of the weight on the main landing gear when the aircraft is within the proper CG range for a 737-800. The max landing weight is about 66,000 kg and the max zero fuel weight is about 62,000 kg, so a weight of 60,000 kg when arriving at the gate seems reasonable for a full flight. If 94% of the weight is on the main gear, this puts the CG at about 1m forward of the main gear, which is towards the aft end but within limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I considered the high density layout shown in the document, which is a single-class layout with 175 economy class seats at 32 inch (0.8m) pitch. The first row has just 3 seats and is located about 14m forward of the main gear, with each row of 6 located another 0.8m aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assumed that the aircraft is unloaded from the front, one row at a time, and that each passenger (plus carry-on) weighs &lt;a href=&quot;https://aviation.stackexchange.com/a/16308/1696&quot;&gt;85kg&lt;/a&gt;. For a rough idea of the results, consider that the CG starts with a moment of about 60,000 kgm&lt;sup&gt;1&lt;/sup&gt;, and the rows forward of the main gear are an average of 7m forward, so removing about 8600kg from those rows will move the CG aft of the main gear and tip the plane. This means about 100 passengers, which is within possibility for 18 rows of seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So with a 60,000 kg aircraft, 94% of the weight on the main gear, and 85kg passengers, the plane will tip after row 13 disembarks. This is very sensitive to CG. If the CG starts at 93% of weight on the main gear, the plane won't tip. If the CG starts fully aft (96% weight on main gear), the plane tips at row 7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the plane isn't really unloaded 1 row at a time. Usually there is a line of passengers down the aisle. If there is 1 passenger per row in the aisle, the plane won't tip at 94% weight on main gear, and won't tip until row 11 at 96% weight on main gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A heavier plane will be harder to tip, and heavier passengers will make it easier to tip. Planes that have upper class passengers in the front will be harder to tip, since less weight is removed from the front of the plane. A longer plane (737-900) will actually be slightly harder to tip, as will a shorter aircraft (737-700)&lt;sup&gt;2&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why doesn't this ever happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I mentioned, it's very sensitive to CG. Only an aft CG will be an issue. Also, passengers in the aisle will help balance things out. Many airlines have larger seats with more room in front that will reduce the effect of passengers leaving these rows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another factor is baggage. As soon as the plane stops and shuts down the engines, the ground crew will often start unloading the plane. It will take a bit longer to position the jet bridge or stairs and begin disembarking passengers. Removing weight from the rear will help balance passengers leaving the front.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reference to the post that created this question, it's unlikely that one passenger would make the difference in tipping the aircraft. However, it is entirely possible that fully unloading the seats in front and not the back, and having no one coming down the aisle, is a risk factor that flight attendants would want to avoid.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;1: I know that the typical unit is Nm but we only care about balance here, not forces, so there is no need to complicate things with gravity.&lt;br&gt;&#xA;2: This may seem strange but for the same weight % (which is how I'm comparing) each aircraft will have a different CG location relative to the main gear, due to the distance between the nose and mains changing. Also, different aircraft have different weights and different CG ranges.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-19T20:43:16.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19100" PostTypeId="2" ParentId="9329" CreationDate="2015-08-19T21:34:35.780" Score="17" Body="&lt;p&gt;From the 1990s at two different airlines in 747-100 and -200 aircraft with 3-man crews. Call outs were the same regardless of whether it was the the Captain or the F.O. flying, so PF=Pilot Flying, NFP=Non Flying Pilot, and FE-Flight Engineer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We'll assume a standard takeoff with more than adequate runway length, no runway contamination. The airplane is lined up, flaps at 10 degrees, the PF is on the brakes. The FE has rotated his seat to a position between the pilots and as far forward as possible. The PF has his hand on the top of the thrust levers. The FE has his hands positioned so that he can readily reach the bottom of the thrust levers to retard them should the PF overboost. Both pilots are primarily looking out the front windshield. The FE is watching the fuel flows, EPRs, and EGTs on the front panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When takeoff clearance is given, the PF starts advancing the thrust levers. The first call comes when it's obvious that all engines are powering up:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;set takeoff power&quot; The call is to the FE, but the PF keeps his hands lightly on the thrust levers in case of an abort. The FE moves the thrust levers to the desired power setting using the EPRs. He may need to jockey them a little.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FE: &quot;power set&quot; given when the FE is happy with the setting, although he will continue to monitor and adjust as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;80 knots&quot; Used by only one of the airlines I flew for. They had an ops specs requirement that if you didn't have full direction control at 80 knots, you were to abort the takeoff. It was in my opinion an unneeded call, and that call plus the actions of a captain very much concerned with following the rules resulted in putting an airplane off a runway at KJFK. The airplane was totaled, only minor injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;V1&quot; The PF takes his hands off the thrust levers since an abort is no longer an option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;rotate&quot; The PF starts raising the nose to a pre-determined pitch attitude, more often than not 12 or 13 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;positive rate&quot; Given by the NFP when he observes the vertical speed go positive. There were also operational noises caused by the removal of the locks that kept the gear lever from being positioned to UP when the aircraft was on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;gear up&quot; The NFP positions the gear lever to the UP position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;V2&quot; Given when the airplane has accelerated to that speed. The PF will maintain that speed until a clean-up height, typically 1000 -1500 feet AGL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFP: &quot;transition&quot; The PF lower the nose to around 5 degrees to start accelerating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;climb power&quot; The FE brings the thrust levers back to climb power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FE: &quot;power set&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;flaps 5&quot; Given when the aircraft has accelerated to the minimum safe airspeed for that configuration. The NFP sets the flaps&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;flaps 1&quot; Again, given when the aircraft has accelerated. At flaps 1 the trailing edge flaps are up, but the leading edge devices are still out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PF: &quot;flaps up&quot; This gives you a clean wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bear in mind that the speeds vary with runway altitude, ambient temperature, and weight of the aircraft. Back in the dark ages of the 1990s these speeds were grease-penciled in on a plastic card by the FE. The card was then handed to the F.O. for verification, and then placed at the front of the thrust level console in easy view. Then the two pilots would position 5 plastic bugs around the perimeter of the airspeed indicator to those speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also bear in mind that this is an 76 year-old man relating from memory that which he last did 16 years ago. He did do it a lot of times, though.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-08-19T21:40:09.763" LastActivityDate="2015-08-19T21:40:09.763" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19101" PostTypeId="2" ParentId="19097" CreationDate="2015-08-19T21:55:43.660" Score="8" Body="&lt;p&gt;ICAO is headquartered in Montreal because that was the &lt;a href=&quot;http://www.icao.int/secretariat/PostalHistory/1946_montreal_confirmed_as_capital_of_international_civil_aviation.htm&quot;&gt;result of a vote&lt;/a&gt; by the founding members (PICAO is Provisional ICAO):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why was Montreal selected? While insisting on the excellent&#xA;  hospitality offered since of the beginnings of PICAO by the federal,&#xA;  provincial and municipal authorities, the delegates described Montreal&#xA;  like a roundabout of the international means of communication and a&#xA;  strategic centre with a formidable economic, scientific, technical and&#xA;  aeronautical expansion being felt for a few years. One insisted on the&#xA;  vast spaces of the Canadian territory, offering unlimited&#xA;  possibilities for the scientific and practical experiments in the&#xA;  field of aviation. Moreover, PICAO was to be established as close as&#xA;  possible to the central head office of the United Nations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And IATA is in Montreal because its founding statutes said that &lt;a href=&quot;http://www.icao.int/secretariat/postalhistory/iata_international_air_transport_association.htm&quot;&gt;it must be in the same location as ICAO&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Article II of the IATA 1945 Statutes states that “The Head Office of&#xA;  this Association shall be maintained in the city in which the&#xA;  headquarters of the International Civil Aviation Organization is&#xA;  located.”; this article was later amended to leave an opening for a&#xA;  possible other place as determined by the General Meeting&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-19T21:55:43.660" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19102" PostTypeId="1" AcceptedAnswerId="21231" CreationDate="2015-08-19T22:33:23.637" Score="14" ViewCount="8806" Body="&lt;p&gt;I understand why JetBlue's IATA code isn't JB since that belongs to a pre-existing helijet service in Canada, but why is it B6?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some history behind the B6 moniker?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastActivityDate="2018-08-11T01:08:58.770" Title="Why is JetBlue's IATA code B6?" Tags="&lt;airline-operations&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19103" PostTypeId="1" AcceptedAnswerId="19105" CreationDate="2015-08-19T22:34:46.973" Score="5" ViewCount="2767" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GXHHb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GXHHb.jpg&quot; alt=&quot;Photo of right side of cockpit, above and below wind screen&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I came across this photo but it doesn't have any other info. What type of plane is it? Also, is it some sort of seaplane perhaps? I say seaplane because it was tagged with the word &quot;seaplane&quot;. Seems Cessna-ish to me but I'm clueless beyond that. Is it possible to identify the exact model?&lt;/p&gt;&#xA;" OwnerUserId="870" LastEditorUserId="1696" LastEditDate="2015-12-15T16:27:18.397" LastActivityDate="2015-12-15T16:27:18.397" Title="What type/model of plane is this?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19104" PostTypeId="1" AcceptedAnswerId="19106" CreationDate="2015-08-19T23:15:37.797" Score="11" ViewCount="5823" Body="&lt;p&gt;I understand how wing tip vortices be effected under a headwind or crosswind. However, what are the differences in effect between tailwind and light quartering tailwind? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it most dangerous when there is a light quartering tailwind?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="5517" LastEditDate="2015-08-20T12:46:45.187" LastActivityDate="2017-01-05T00:02:09.993" Title="Why do wing tip vortices tend to be most dangerous when there is a light quartering tailwind?" Tags="&lt;wing-tip-vortex&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19105" PostTypeId="2" ParentId="19103" CreationDate="2015-08-19T23:16:15.997" Score="7" Body="&lt;p&gt;It looks like a Cessna 208 Caravan to me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/loF5S.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/loF5S.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NNkFX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NNkFX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are single-engine high-wing turboprops, useful for a variety of cargo and passenger-hauling tasks. Here's what a 208 in seaplane configuration looks like on the outside:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QA1aF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QA1aF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your photo looks like an older plane with the original radio stack and no glass, unlike these newer cockpits. In addition, somewhat startlingly, the right-hand control column and yoke have been removed, but they bothered to keep the copilot's 6-pack. That's odd, from my sensibilities, and it tells me the plane was altered in the cheapest possible way for use as a pure short-range passenger ferry. The right-hand seat can now accomodate an extra passenger (and becomes the best in the house for enjoying the view), without the possibility of that non-flier binding up the pilot's controls.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-19T23:59:06.620" LastActivityDate="2015-08-19T23:59:06.620" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19106" PostTypeId="2" ParentId="19104" CreationDate="2015-08-19T23:54:18.623" Score="9" Body="&lt;p&gt;According to the FAA's &lt;a href=&quot;https://www.faa.gov/training_testing/training/media/wake/04SEC2.PDF&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Pilot and Air Traffic Controller Guide to Wake Turbulence&lt;/em&gt;&lt;/a&gt; (section 2.4.5) it's because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Light&lt;/strong&gt;: in light winds the vortices stay around longer; if the wind is greater than 5 knots then the vortices move out of the way quickly and break up&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Quartering&lt;/strong&gt;: crosswinds blow the vortices across the aircraft's flight path, which means that if you're landing next then one vortex might still be over the runway. With no crosswind at all, the vortices will dissipate on each side of the runway, out of your way.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Tailwind&lt;/strong&gt;: the vortices are blown in the same direction as the aircraft, which means that the vortices from a landing aircraft will be blown down the runway rather than away from it. Again, that's an issue for the next aircraft landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;They have a handy diagram to illustrate the vortex paths from an aircraft at 0, 3 and 6 knots. You can see that a light, 3-knot crosswind causes one vortex to still be in the flightpath after 20 seconds, whereas with 0 or 6 knots of wind the vortex is out of the flightpath completely. You can't see tailwind on this diagram, of course, but the principle is the same: it blows the vortex down the runway (flightpath) rather than away from it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Me01x.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Me01x.png&quot; alt=&quot;Crosswind effect&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-19T23:54:18.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19107" PostTypeId="2" ParentId="19104" CreationDate="2015-08-19T23:57:20.307" Score="9" Body="&lt;p&gt;The wing tip vortices cause significant problems for (small) aircraft taking off after a large aircraft. the FAA Advisory circular &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=9&amp;amp;ved=0CD8QFjAIahUKEwiWld-ipbbHAhXCWhoKHaujBtk&amp;amp;url=http%3A%2F%2Fwww.faa.gov%2FdocumentLibrary%2Fmedia%2FAdvisory_Circular%2FAC_90-23G.pdf&amp;amp;ei=DxDVVdbRO8K1aavHmsgN&amp;amp;usg=AFQjCNHVHzPJkcprFQoyK-5Dx8yHkL0ceg&amp;amp;bvm=bv.99804247,d.d2s&amp;amp;cad=rja&quot; rel=&quot;nofollow noreferrer&quot;&gt;90-23G&lt;/a&gt; deals with this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aircraft takes off, the the vortices sink behind the aircraft and move laterally over the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uXlCP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uXlCP.jpg&quot; alt=&quot;Vortices sink during takeoff&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: FAA Advisory Circular 90-23G &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of no crosswind, the vortices simply move laterally away from the runway at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wnfdf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wnfdf.jpg&quot; alt=&quot;Vortices&amp;#39; movement in zero crosswind&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: FAA Advisory Circular 90-23G&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume that the aircraft is landing after another one. However, if there is a tailwind, the trailing vortices of the preceding aircraft can be moved into the final approach of the landing aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case there is a crosswind, the lateral movement of the upwind vortex is decreased while that of the downwind vortex is increased. This means that the upwind vortex remains in the runway longer than it would be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/H1uEr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H1uEr.jpg&quot; alt=&quot;Vortex movement with crosswind&quot;&gt;&lt;/a&gt;&#xA;Source: FAA Advisory Circular 90-23G&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus a quartering tailwind presents the worst of both worlds: It move the upwind vortex right in the path of the incoming aircraft and keeps it there longer than usual. The situation is similar for takeoffs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zFyqS.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zFyqS.gif&quot; alt=&quot;Quartering Tailwind&quot;&gt;&lt;/a&gt;&#xA;Source: www.gleim.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason it is considered to be the most dangerous situation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-19T23:57:20.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19108" PostTypeId="2" ParentId="19104" CreationDate="2015-08-19T23:59:52.210" Score="1" Body="&lt;p&gt;Very simply:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A strong tailwind would break up the vortices more quickly.&lt;/li&gt;&#xA;&lt;li&gt;Quartering, as in not straight on, means the upwind vortex is blown into the path of the next aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-19T23:59:52.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19109" PostTypeId="1" AcceptedAnswerId="19112" CreationDate="2015-08-20T00:02:10.733" Score="2" ViewCount="5358" Body="&lt;p&gt;Most commercial airplanes have the wings on the bottom of the aircraft to lift the body better, but what about the sugar volt concept that has the wing on the top&lt;a href=&quot;https://i.stack.imgur.com/c69Zf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c69Zf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-20T07:13:15.103" Title="What are some advantages and disadvantages of have the wing on top of the airplane?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;lift&gt;" AnswerCount="3" CommentCount="1" ClosedDate="2015-08-21T00:00:41.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="19110" PostTypeId="2" ParentId="2198" CreationDate="2015-08-20T00:02:11.160" Score="0" Body="&lt;p&gt;Some 400 aircraft already do this via the AFIRS system, which uses Iridium satellite constellations to communicate.  It costs some $100K to install.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that Inmarsat has a free tracking offer, free as in customers that are paying for services from third-party providers.  Doesn't have complete worldwide coverage.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to why it hasn't been mandated, I do believe it has to do with necessity with cost benefit analysis / risk management vectors until recently not requiring it.  With the search costs of AF447 reaching 100M and the at least $80M spent on the MH370 search, the risk profile may now provide some impetus to install such technology.  If only to reduce cost exposure in the event of a loss and to gain the advantages provided by real-time monitoring of aircraft systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is that it hasn't been seen as a necessity, but it is technological a reality already with some aircraft already carrying the systems.&lt;/p&gt;&#xA;" OwnerUserId="8375" LastActivityDate="2015-08-20T00:02:11.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19111" PostTypeId="2" ParentId="19093" CreationDate="2015-08-20T00:29:37.773" Score="0" Body="&lt;p&gt;I remember reading about another one--GA aircraft, a drug runner, the pilot jumped once he was intercepted.  The plane continued on until it ran out of fuel.  Someone involved (it's been too long since I read about it to remember who) was trying to get permission to shoot it down as it was heading for a city.  It was not shot down, it flew over the city and went down at sea when the fuel ran out.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-08-20T00:29:37.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19112" PostTypeId="2" ParentId="19109" CreationDate="2015-08-20T00:42:19.053" Score="4" Body="&lt;p&gt;In smaller aircraft, a high wing is less likely to naturally enter a spiral dive; the low CG (center of gravity) relative to the CL (center of lift) means the plane tends to return to a wings-level attitude instead of staying in a bank if a thermal kicks a wing up. This isn't as much a concern with something as big as your pictured airliner concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger high-wings mean there isn't a big wing spar and fuel systems running across or just underneath your cargo deck. This is a major reason military transports are high-wing, so the deck can be flat without taking up usable cargo volume raising the entire deck above the wing spar (the high wing also keeps the engines safe from the hazards of &quot;unimproved&quot; landing strips in forward bases). However, in a commercial airliner, it means that spar is now running through your passenger cabin, which is why you don't see it much on jet airliners (the Dash 8 and other turboprops use it by necessity, and typically require a &quot;camel hump&quot; to get the spar up out of the cabin). This concept seems to split the difference, using a thin brace underneath the fuselage to reinforce a thinner high-wing spar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High wings, especially swept wings on high-mass planes, have an increased tendency to Dutch roll. This is a &quot;stable instability&quot; where one wing gains lift due to a slight crosswind or yaw/sideslip, lifting that wing and inducing a bank, which creates a sideslip toward the other side which lifts &lt;em&gt;that&lt;/em&gt; wing and induces a sideslip in the other direction. This ultimately results in a circular or figure-8 rocking motion of the fuselage not unlike the rolling of a ship, which can make passengers queasy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;High-wing aircraft tend to be more susceptible to this because their center of gravity is below their center of lift, and so their natural tendency is to return to wings-level, but on large heavy aircraft this settling takes time, during which the plane develops the sideslip that lifts the opposing wing, causing the overcorrection that continues the rolling motion. To counteract this, large high-wing aircraft are usually designed with some anhedral (downward) angle in the wing. This first lowers the center of lift, as some of the wing is now closer to the center of mass. More importantly, the lift vector of each wing now points outward from the fuselage instead of directly up in opposition to gravity. These two changes combine to relax the plane's natural tendency to self-level, and thus the tendency to Dutch roll, at the cost of keeping the pilot a little busier making small inputs to keep the plane level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low-wing aircraft tend to avoid Dutch roll in the opposite way; their center of gravity is above the wings' center of lift. Because of this, the plane will tend to remain in a banked angle, similar to a high-wing with anhedral but for different reasons. Because this can lead to instabilities like spiral departures including the dreaded spiral dive, low aircraft wings are typically given a dihedral (upward) angle, which gives the aircraft some self-stabilizing characteristics at low bank angles while still avoiding Dutch roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, as illustrated by aeroalias's answer, high wings have high engine mounts. Most modern airliner designs have under-wing engines which can be accessed from very near the ground (either standing or on a simple stepladder), and removed from the aircraft while supported with fairly simple cradles on casters. Engines mounted high on the airframe (such as on high-wing aircraft but also the fuselage-mounted engines of T-tails and the centerline engine of tri-engines like the DC-10 and 727) can require a cherrypicker to get to, and powerful accordion lifts to support the engine as it's being removed. This increases maintenance costs and reduces the opportunity for meaningful inspections at the gate.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-20T02:20:58.580" LastActivityDate="2015-08-20T02:20:58.580" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19113" PostTypeId="2" ParentId="19109" CreationDate="2015-08-20T00:53:26.587" Score="2" Body="&lt;p&gt;The position of the wing is determined by the required stability, the necessity to land in unprepared runways, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the high wing aircraft have more lateral stability compared to the low wing design. In case of low wing design, the desired stability is achieved by dihedral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The low wing has the advantage of easy maintenance as they are near to the ground. In case of high wing, it usually requires specialized equipment for servicing the engine etc.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/E2apA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E2apA.jpg&quot; alt=&quot;737 Engine maintenance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source: www.aviation-news.co.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RX89B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RX89B.jpg&quot; alt=&quot;C17 maintenance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.robins.af.mil&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage of high wing is that the aircrafts can be landed on unprepared and semi-prepared runways as the high wing (and engine position) offers some protection against debris.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cGfIt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cGfIt.jpg&quot; alt=&quot;C17 landing in unprepared runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:www.saairforce.co.za&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, in case of high wing aircraft, the ground effect is lower. This prevents the smaller aircrafts from 'floating' and improves the landing characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Form structural point of view, the high wing aircrafts can have a flat floor for easy loading/unloading and using standard pallets. In case of low wing, the spar will run through that section of the fuselage. On the other hand, a high wing design limits the cabin height for the same reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of civil aircraft, the ease of maintenance is one the main reasons for using low wing. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-20T00:53:26.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19114" PostTypeId="1" AcceptedAnswerId="19116" CreationDate="2015-08-20T01:13:17.660" Score="27" ViewCount="12798" Body="&lt;p&gt;I would like to know if a prop plane, for example the P-51, could be able to fly backward. Is it possible through some trick like changing blade angle or reverse the prob rotation direction? It would have been hard for piloting, but is this theoretically possible?&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="9126" LastEditDate="2015-08-21T04:17:51.923" LastActivityDate="2015-12-23T23:34:52.097" Title="Can a plane fly backward if its propeller is in reverse?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="8" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19115" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T01:51:26.810" Score="4" Body="&lt;p&gt;There is a relation between the thrust provided by the engine and the lift created by the profile of the wings. Usually this relation is not the same backwards, so it will not fly backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller planes like the P-51 has an asymmetric aerodynamic profile that cannot provide the same lift moving backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is some aerodynamic profiles that are near to be symmetric, but requires a power plant much greater than a propeller. Usually this power plant cannot provide the same thrust backwards than forward.&lt;/p&gt;&#xA;" OwnerUserId="9876" LastActivityDate="2015-08-20T01:51:26.810" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19116" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T02:10:57.727" Score="41" Body="&lt;p&gt;Fly? No.&lt;br&gt;&#xA;Wings generally only produce enough lift to keep an aircraft aloft when air is flowing over them in their intended direction. If you reverse the airflow over the wing (by moving backwards in the air, for example) the wing would no longer be producing the necessary lift, and the aircraft would &quot;descend at an extremely rapid rate&quot; until a normal airflow over the wings was restored. (That's the polite way of saying &quot;the darn thing falls out of the sky like a rock!&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Move? Yes. At least on the ground.&lt;br&gt;&#xA;This has been demonstrated on more than one occasion by &lt;a href=&quot;https://youtu.be/2C6tu9LNMs0?t=8m10s&quot; rel=&quot;nofollow&quot;&gt;Fat Albert&lt;/a&gt;, the C-130 that supports the Blue Angels.  While the propellers themselves do not reverse, the blade pitch is changed to produce reverse thrust (slowing the aircraft the same way thrust reversers do on a jet engine, and in this case &lt;em&gt;reversing&lt;/em&gt; its direction of travel).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that there is one notable exception to the &quot;airplanes can't fly backwards&quot; rule, &lt;a href=&quot;/questions/19114/can-a-plane-fly-backward-if-its-propeller-is-in-reverse#comment43813_19114&quot;&gt;which the article Ethan linked to alludes to&lt;/a&gt;: If the wind velocity exceeds the aircraft's stall speed it's possible for an aircraft to &quot;fly&quot; at its minimum airspeed, but be moving backwards relative to the ground.&lt;br&gt;&#xA;This is a bit of a cheat though: The airplane still thinks it's flying forward (the relative velocity of the wind over the wings is in the &quot;normal&quot; direction, and the &lt;em&gt;airspeed&lt;/em&gt; is fast enough to create enough lift to sustain flight). It just happens the the airspeed includes a headwind component sufficient to give the aircraft a net &quot;negative&quot; &lt;em&gt;groundspeed&lt;/em&gt;.&lt;br&gt;&#xA;The hypothetical P-51 in your question would require sustained winds of about 83 knots to make this trick work (we generally call that a hurricane), but something like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_J-3_Cub&quot; rel=&quot;nofollow&quot;&gt;Piper Cub&lt;/a&gt; can do it at much more reasonable wind speeds.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="4474" LastEditDate="2015-12-23T23:34:52.097" LastActivityDate="2015-12-23T23:34:52.097" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="19117" PostTypeId="1" AcceptedAnswerId="19118" CreationDate="2015-08-20T02:22:14.383" Score="2" ViewCount="1052" Body="&lt;p&gt;In my mind this seems like a bad idea for a lot of reasons, like the dumped fuel lighting on fire itself, or perhaps leaving fuel vapor in the wing tanks (which may be even worse than regular liquid fuel) or even just because if you do put the fire out you would now have a new emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, I've been wrong before.  Perhaps it would actually help put out the fire and being forced to glide would be an improvement over an engine fire, right?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I thought I'd simply ask the experts.  Might a large commercial jet (like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow&quot;&gt;B747&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;nofollow&quot;&gt;A380&lt;/a&gt;, etc) dump it's fuel if an engine caught on fire in order to starve the fire of fuel?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;PS- For the sake of this thought experiment, pretend the fire had robbed the engine of the ability to cease fuel flow to it...  Unless that really makes no sense, in which case please feel free to call me on it and that can be the answer.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-09-04T16:23:06.433" Title="Might a large commercial jet dump fuel if an engine were on fire?" Tags="&lt;safety&gt;&lt;fire&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19118" PostTypeId="2" ParentId="19117" CreationDate="2015-08-20T02:37:42.750" Score="12" Body="&lt;p&gt;An airliner experiencing an engine fire might dump fuel, but not to starve the engine. That is much more easily accomplished by simply shutting down the fuel pumps to that engine, which would be a first-line firefighting technique as it's the most economical and the most likely to allow for a restart (less maintenance is required on an engine that's simply shut down versus one that's been doused with chemical suppressors, and those same chemical suppressors might extinguish the fire but would also inhibit relighting it). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several redundant fuel shutoff systems in most airliners, from the fuel pumps themselves to actual shutoff valves in the fuel lines in case the pumps themselves are the failure point. Any failure that would completely prevent the crew shutting off the fuel supply to a damaged engine would likely create much more immediate problems, like severe structural damage to the wing or fuselage of the aircraft. All of these shutoffs in addition to active fire suppression systems such as chemical extinguishers are under the flight crew's manual control; an engine on fire is usually still producing at least some thrust, which may be more important than extinguishing the fire in certain critical phases of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane is more likely to dump fuel if it's close to its departure airport when the emergency occurs. In such a scenario, the aircraft is likely above its maximum landing weight (which is less than the max takeoff weight as the forces on the landing gear and the runway are less on takeoff than for landing and the plane is expected to burn most of its fuel weight by the time it gets where it's going), and therefore the fuel dump is simply to reduce the aircraft's weight for an emergency landing, so the landing gear doesn't collapse on touchdown. Additionally, if anything else goes wrong during the landing, dumping fuel would leave the plane with as little fuel as possible to minimize the spread or intensity of a fire on the ground, which can impede or prevent escape from the plane. However, fuel dumps from commercial aircraft are rare, used in situations where the necessity of dumping fuel to land safely and spare the passengers outweighs the financial costs of losing the fuel and the environmental costs of cleaning up the spill.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-04T16:23:06.433" LastActivityDate="2015-09-04T16:23:06.433" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19119" PostTypeId="2" ParentId="19095" CreationDate="2015-08-20T03:14:34.230" Score="5" Body="&lt;p&gt;To add to @PeterKämpf's answer: the basic design methodology will be unchanged so long as the laws of physics remain unchanged. But the &lt;em&gt;method of application&lt;/em&gt; of the methodology is changing very fast, and will continue to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a mech eng student, the OP is unlikely to have any real-world experience of the engineering environment in which Roskam's 8-volume set of books were first published, in 1985-1990 (according to Wikipedia). That is 25 to 30 years ago. As just one example, the fastest computer in the world back then (the Cray-2) had a clock speed slower than any modern PC except for cheap laptops or tablets, and less RAM than an top-of-the range modern cellphone. And with a price tag of around $20m, that computing resource would be shared between hundreds or perhaps thousands of users, not sitting on an engineer's desk for his or her exclusive personal use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today you don't need to &quot;estimate fuel fractions for different mission segments from historical correlations&quot;. You can look at the accurate real-time data being collected automatically by every modern aircraft that your company has built, and look at it for negligible marginal cost. You don't need to approximate from a &quot;historical log-lin correlation&quot; - again, you can look at the actual data, in as much detail as you need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This accelerating rate of change presents educators with some serious challenges. The university engineering departments don't have access to all that real-time data, and even if they did they are (correctly, IMO) trying to teach some general principles, not the specifics of what Company X does this week. But the danger is that the students work through the case studies in an excellent collection of 25-year-old books, and without any other input, they get the wrong idea that those case studies still represent the current state of the art. &lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-08-20T03:14:34.230" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19120" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T04:01:57.530" Score="18" Body="&lt;p&gt;In short, no. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the wing of an aircraft is designed to produce lift in only one direction. Airflow moving backwards over the airfoil would not be directed around it properly; the air coming across what's supposed to be the trailing edge would be divided too cleanly (so it could stall too easily) and wouldn't be accelerated as quickly by the gentler slope on what's supposed to be the back side of the wing, thus reducing lift. The leading edge, now the trailing edge, would increase drag and further reduce lift as the boundary layer would separate too soon along its curve. In other words, a wing moving backward produces very little lift and much more drag, both bad for an airplane trying to stay in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, most propeller-driven aircraft have their wing chords angled slightly upward from the thrust vector of the engine, which provides a nonzero angle of attack in level flight. This provides more lift at the cost of slightly higher drag, and allows a plane to maintain altitude more easily at cruising speeds with the nose level. In reverse &quot;flight&quot;, this would end up a negative angle of attack, reducing lift even further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, the horizontal stabilizer is designed to provide downforce in forward flight to counteract a slightly forward center of gravity (this basic design causes desirable stall behavior, causing the plane to nose down to restore normal airflow). This is accomplished in low wings with a slight downward angle of the horizontal stabilizer (or a slight up-angle to canards), and in high-wings by using the downwash from the wing to push on the tail. Moving backward, there's no downwash to balance the weight at the nose, and a downward cant would actively push the tail up as the wind moved past it, in either case flipping the plane into a nose-down attitude (also a desirable recovery behavior if you find yourself hanging by your prop).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a stellar engineering choice by aircraft designers, they orient the curve of the wings and trim the horizontal stabilizers to produce lift and balancing trim force when the aircraft is moving in the direction its occupant(s) would call &quot;forward&quot;, i.e. the direction the pilot's seat is facing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few aircraft, notably late Soviet designs like the MiG-29 and Su-27, that were engineered for desirable &quot;post-stall&quot; behavior. These aircraft are capable of remaining stable and controllable in extreme angles of attack (exceeding 90° off-chord) and are the best examples of an aircraft that can &quot;fly backward&quot;, at least for a couple of seconds. The maneuvers involved include the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tailslide&quot; rel=&quot;nofollow&quot;&gt;tailslide&lt;/a&gt; (pull in to the vertical, stall nose-up, and fall back to earth tail-first, then pull back on the stick to kick your tail out behind you and drop the nose to recover) and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pugachev%27s_Cobra&quot; rel=&quot;nofollow&quot;&gt;cobra&lt;/a&gt; (from full throttle, cut the engine and pitch up &lt;em&gt;hard&lt;/em&gt; to intentionally stall the aircraft and rotate nose-up, then center the stick to allow the plane to nose-down). Most counterpart U.S. aircraft are incapable of these maneuvers as they're engineered to avoid stalling, following the &quot;energy management&quot; theory of Western combat maneuvering (where stalling, regardless of airspeed, means you're out of energy to maneuver, as you either have insufficient forward airspeed to maintain your turn, or you've just turned your plane's wings into air brakes).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="4474" LastEditDate="2015-12-23T23:29:43.670" LastActivityDate="2015-12-23T23:29:43.670" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19121" PostTypeId="2" ParentId="19109" CreationDate="2015-08-20T07:13:15.103" Score="5" Body="&lt;p&gt;The SUGAR Volt and SUGAR Freeze concepts use a high wing purely to make effective bracing possible. It is a design for a world where oil costs $200 per barrel and above. Mainly, two things make its aerodynamics much more efficient than current designs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A very high aspect ratio of its wing, enabled by the bracing, and&lt;/li&gt;&#xA;&lt;li&gt;A lower flight Mach number, which in turn makes the wing more efficient by requiring less sweep. Boeing doesn't give a Mach number in their &lt;a href=&quot;http://www.boeing.com/aboutus/environment/environment_report_14/2.3_future_flight.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;web page&lt;/a&gt;, but I would bet it is somewhere around 0.75. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/15375/d8-double-bubble-aircraft-by-nasa/15392?s=1%7C0.2643#15392&quot;&gt;here&lt;/a&gt; for a discussion of a very similar design.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Todays airliners use a low wing to enable them to stow away their long landing gears and to put the wing spar below the passenger deck. Long gears make it possible to stretch the fuselage and still be able to rotate during take-off. Large high-wing aircraft, with their low fuselage position, are easier to load and unload, at the price that the fuselage taper has to start shortly aft of the landing gear, so no stretching is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both concepts use rather speculative engine designs, in case of the SUGAR Volt even one with hybrid natural gas / electric propulsion with onboard batteries. The SUGAR Freeze uses a less speculative engine burning liquefied natural gas. In the SUGAR study, &lt;a href=&quot;https://www.youtube.com/watch?v=oz3tzG9RxKI&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing set the goal&lt;/a&gt; to reduce fuel consumption by 70%.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-20T07:13:15.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19122" PostTypeId="1" AcceptedAnswerId="19125" CreationDate="2015-08-20T07:55:39.807" Score="26" ViewCount="3831" Body="&lt;p&gt;Could an aerofoil be designed to give reasonably good lift for both flow directions?&lt;/p&gt;&#xA;&lt;p&gt;I was motivated by this related question on Aviation SE: &lt;a href=&quot;https://aviation.stackexchange.com/questions/19114/can-a-plane-fly-backward-if-its-props-in-reverse&quot;&gt;Can a plane fly backward if its propeller is in reverse?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;It seems that in practice most wings are indeed optimized for one direction of travel. And that makes sense in the context of the use case they are designed for.&lt;/p&gt;&#xA;&lt;p&gt;But hypothetically, had a designer to design a wing profile for an aircraft that wanted to be able to fly both ways could it be done? The means of flow reversal could be varied e.g. reversible pitch propellers etc.&lt;/p&gt;&#xA;&lt;p&gt;Any examples of such profiles?&lt;/p&gt;&#xA;&lt;h3&gt;Why Would You Want To Do This?&lt;/h3&gt;&#xA;&lt;p&gt;I don't have a good answer here. Maybe just curiosity.&lt;/p&gt;&#xA;&lt;p&gt;More speculation: It could give a fighter or acrobatic aircraft some special manouveres? The ability to reverse without stalling at the end of a steep climb etc.?&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Modified Question:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;What about an aerofoil that's primarily optimized for forward flow but still has sufficient lift to not perform abyssmally in reverse? i.e. Not strictly symmetric performance. With good lift to drag ratios in forward flight but somewhat draggy in reverse.  Say, a use case where 99% of the flight time is in forward motion but for the other 1% you don't want absolute crap lift in reverse motion.&lt;/p&gt;&#xA;&lt;p&gt;Perhaps this flexibility can bring out more creativity in the designs?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-02-29T12:39:57.130" Title="Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward?" Tags="&lt;aerodynamics&gt;&lt;theory&gt;&lt;airfoil&gt;" AnswerCount="8" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19123" PostTypeId="1" CreationDate="2015-08-20T08:37:50.960" Score="6" ViewCount="1531" Body="&lt;p&gt;The answer to &lt;a href=&quot;https://aviation.stackexchange.com/a/15538/3775&quot;&gt;another question&lt;/a&gt; mentions the rather unusual &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_AD-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;pivot wing&lt;/a&gt;. From an aerodynamical standpoint, what are the benefits of an oblique wing compared to a delta, a trapezoid or a forward swept wing? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any other differences?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that I am asking about the oblique wing when it is oblique. The advantages of variable-sweep aircraft have already been &lt;a href=&quot;https://aviation.stackexchange.com/questions/1726/why-do-some-military-aircraft-use-variable-sweep-wings/3699#3699&quot;&gt;discussed at length&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="22726" LastEditDate="2019-09-29T01:44:30.980" LastActivityDate="2019-09-29T01:44:30.980" Title="What are the benefits of a pivot wing?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;wing-sweep&gt;&lt;oblique-wing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19124" PostTypeId="2" ParentId="19123" CreationDate="2015-08-20T09:18:53.453" Score="0" Body="&lt;p&gt;I think the main difference between a swept and a straight wing is that the straight wing has a lower landing speed, whereas the swept wing can fly closer to the speed of sound without compressibility problems. So a pivot wing gives the benefit of both, the disadvantage being extra weight of the pivot mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Peter Garrison explains the benefits of a swept wing here: &lt;a href=&quot;http://www.flyingmag.com/why-are-wings-swept&quot; rel=&quot;nofollow&quot;&gt;http://www.flyingmag.com/why-are-wings-swept&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-08-20T09:37:39.687" LastActivityDate="2015-08-20T09:37:39.687" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="19125" PostTypeId="2" ParentId="19122" CreationDate="2015-08-20T09:19:14.960" Score="26" Body="&lt;p&gt;There is no airfoil with good lift in both flow directions, but one with some lift is conceivable. However, the lift-to-drag ratio will be nothing to write home about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reasonable candidate would be created if we use the forward half of the venerable NACA 66(2)-415 and copy it again for the last half. Like that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4fy2Z.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4fy2Z.png&quot; alt=&quot;NACA 66415 with mirrored front half&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you might recognize from the plot, this was done with &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;noreferrer&quot;&gt;XFOIL&lt;/a&gt;. However, the iteration does not converge. But when real air hits this thing, it will create lift, much like a cambered plate will do. Its inviscid zero angle lift coefficient is already 0.5, however, viscous effects will reduce this lift coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a good airfoil, the pointed trailing edge defines the point for flow separation, while the rounded nose leaves it to the flow to find a suitable stagnation point. Here we have a rounded contour on both ends, so the separation point widens to a separation area, and this will creep up on the top side once the flow develops some suction at the top. Hence, lift will be poor and drag will be high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a little trick, XFOIL can be convinced that this is a regular airfoil with a really blunt trailing edge. Then this is the result at a Reynolds number of 5 million and Mach 0.3:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ymzuG.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ymzuG.png&quot; alt=&quot;XFOIL plot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, now the separation at the trailing edge is prescribed and will not as easily move up, so the results might be too positive. It seems that L/D exceeds 70 (which surprises me! The original 66(2)-415 has a lower L/D at the same flow conditions, which is a strong hint that we are misusing XFOIL here). Compare that to a good glider airfoil L/D of over 200 at this Reynolds and Mach number.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Applicability&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I cannot think of a good reason to do this. The consequences of flying backwards include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What was stable previously will become unstable - in all directions! Remember that the neutral point is at the quarter chord, measured in flow direction. If the flow direction is reversed, the distance between neutral point and center of gravity will suddenly be more than half the wing chord - in the wrong direction! The same goes for the vertical, which is now destabilizing.&lt;/li&gt;&#xA;&lt;li&gt;This includes all control surfaces: They will run into their stops and stay at maximum deflection. A manual control system will become unusable, and even a hydraulic, computer-controlled one will experience extreme loads which overpower conventional actuators. When combined with &lt;a href=&quot;https://en.wikipedia.org/wiki/Gurney_flap&quot; rel=&quot;noreferrer&quot;&gt;Gurney flaps&lt;/a&gt; or directed blowing on both sides, the control issues should become manageable.&lt;/li&gt;&#xA;&lt;li&gt;If done with reversing a variable-pitch propeller, most of the propeller will not work anymore, because the blade twist runs now opposite to how it should. You could, however, create enough thrust if you use a VJ-101 style propulsion where the engine gondolas swivel through 180°.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QVwCw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QVwCw.jpg&quot; alt=&quot;VJ-101 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VJ-101 (picture &lt;a href=&quot;http://www.wind-tunnel-models.com/Avions_VJ-101_C.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: @Marius mentioned in a comment below the &lt;a href=&quot;https://www.helis.com/70s/h_s72.php&quot; rel=&quot;noreferrer&quot;&gt;S-72 X-Wing&lt;/a&gt;, an attempt to make a helicopter go faster by stopping the rotor above a certain forward speed. The &lt;a href=&quot;https://sites.google.com/site/stingrayslistofrotorcraft/sikorsky-s-72-rsra--x-wing&quot; rel=&quot;noreferrer&quot;&gt;X-Wing&lt;/a&gt; actually used an elliptical airfoil and forced the Kutta condition by directed blowing. This enabled it also to use a rigid wing and to adjust blade lift for cyclic and collective control by blowing. This is indeed the only sensible application of an airfoil that works in both directions.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;ANOTHER EDIT: I just found &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=dbln526-il&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; on Airfoiltools.com: The Sikorsky DBLN-526 double ended rotorcraft airfoil. It was most likely used on the S-72, and its 26% would only work with directed blowing, anyway. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-06-22T00:46:30.527" LastActivityDate="2018-06-22T00:46:30.527" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="19126" PostTypeId="5" CreationDate="2015-08-20T09:31:38.307" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-08-20T09:31:38.307" LastActivityDate="2015-08-20T09:31:38.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19127" PostTypeId="4" CreationDate="2015-08-20T09:31:38.307" Score="0" Body="Angle of a line from root to tip, 25% of the way back from the leading edge, measured from the perpendicular to the longitudinal axis of the aircraft. " OwnerUserId="3775" LastEditorUserId="1961" LastEditDate="2015-08-20T10:47:44.423" LastActivityDate="2015-08-20T10:47:44.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19128" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T09:34:39.440" Score="7" Body="&lt;p&gt;When, as a youngster, I made model planes, I tried this. The result is very unstable and usually the tail lifts on launch causing the aircraft to flip over. I think that, with the use of computer control to counteract the inherent instability and a specially made propeller it might be possible but the development time and expense means that no-one would ever try to do it..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is that the tail assembly of a standard configuration acts like a weather vane. It naturally wants to turn away from the direction of airflow.&lt;/p&gt;&#xA;" OwnerUserId="9417" LastActivityDate="2015-08-20T09:34:39.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19129" PostTypeId="2" ParentId="19097" CreationDate="2015-08-20T09:42:17.073" Score="2" Body="&lt;p&gt;In addition to Pondlife's answer, it may be worth noting that Montreal is an important place in aviation history as the Convention for the Unification of Certain Rules for International Carriage by Air (now known as the Montreal Convention) was signed there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Montreal_Convention&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Montreal_Convention&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.iata.org/policy/pages/mc99.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.iata.org/policy/pages/mc99.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9867" LastActivityDate="2015-08-20T09:42:17.073" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19130" PostTypeId="1" AcceptedAnswerId="19138" CreationDate="2015-08-20T10:02:25.117" Score="13" ViewCount="8072" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/19123/what-are-the-benefits-of-a-pivot-wing#19124&quot;&gt;This question&lt;/a&gt; asks about the benefits of an oblique wing over a delta wing, but I am more interested in the benefits of an &lt;a href=&quot;https://en.wikipedia.org/wiki/Oblique_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;oblique wing&lt;/a&gt; compared to a &lt;a href=&quot;https://en.wikipedia.org/wiki/Variable-sweep_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;swing wing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Oblique_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This is a variation on the classic swing-wing design, intended to simplify construction and retain the center of gravity as the sweep angle is changed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But I'm pretty sure there are a lot more advantages or disadvantages, in terms of stalling behavior (forward swept side inboard first, aft swept side outboard first), aircraft control etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/2360/what-are-the-advantages-of-a-forward-swept-wing-over-a-rearward-swept-wing&quot;&gt;What are the advantages of a forward-swept wing over a rearward-swept wing?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="22726" LastEditDate="2019-09-29T01:44:42.170" LastActivityDate="2019-09-29T01:44:42.170" Title="What are the advantages and disadvantages of an oblique wing over a swing wing?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing-sweep&gt;&lt;oblique-wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19132" PostTypeId="5" CreationDate="2015-08-20T11:20:38.403" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-08-20T11:20:38.403" LastActivityDate="2015-08-20T11:20:38.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19133" PostTypeId="4" CreationDate="2015-08-20T11:20:38.403" Score="0" Body="Next Generation Air Transportation System. A national airspace system proposing to transform America’s air traffic control system from a ground-based system to a satellite-based system." OwnerUserId="3775" LastEditorUserId="15733" LastEditDate="2016-07-12T00:43:56.033" LastActivityDate="2016-07-12T00:43:56.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19134" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T11:30:13.467" Score="3" Body="&lt;p&gt;If reverse thrust was generated (you couldn't do this simply by reversing the prop) then a plane &lt;strong&gt;could&lt;/strong&gt; fly backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the wings are shaped to generate lift as they pass through the air in the forward direction, by using angle of attack and enough thrust you can generate lift in any direction. Angle of attack changes the apparent profile of the wing. The same principle allows planes to fly upside down or sideways in knife edge. The simplest example is how a paper plane can still glide with completely flat wings.&lt;/p&gt;&#xA;" OwnerUserId="1717" LastEditorUserId="1717" LastEditDate="2015-08-20T11:45:04.930" LastActivityDate="2015-08-20T11:45:04.930" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19135" PostTypeId="1" CreationDate="2015-08-20T11:31:45.450" Score="7" ViewCount="9727" Body="&lt;p&gt;Can someone clearly explain the advantages and disadvantages of ruddervators? I cannot find the answer anywhere else. &lt;/p&gt;&#xA;" OwnerUserId="9884" LastEditorUserId="64" LastEditDate="2015-08-20T16:13:50.787" LastActivityDate="2015-08-21T07:59:41.200" Title="What are the advantages and disadvantages of ruddervators?" Tags="&lt;aircraft-design&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19136" PostTypeId="2" ParentId="838" CreationDate="2015-08-20T11:34:42.243" Score="8" Body="&lt;p&gt;Not only the 787 with CFRP has this, all wings flex a lot as shown by the lower part of this image.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/igVdz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/igVdz.jpg&quot; alt=&quot;B52 deformation&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;https://books.google.nl/books?id=KG3xCAAAQBAJ&amp;amp;pg=PA479&amp;amp;lpg=PA479&amp;amp;dq=rigid%20wing%20jig%20shape&amp;amp;source=bl&amp;amp;ots=54tuX6YSa5&amp;amp;sig=SffFn609gMWysb_gXRltY9-Bf28&amp;amp;hl=nl&amp;amp;sa=X&amp;amp;ved=0CDoQ6AEwA2oVChMIkIjYssS3xwIVTLwaCh1zwA9_#v=onepage&amp;amp;q=rigid%20wing%20jig%20shape&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;Introduction to Transonic Aerodynamics &lt;/a&gt; by R. Vos and S. Farokhi&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These days, designers incorporate the flexing into the design, making sure that the shape in cruise is exactly as they want it.&#xA;But the two graphs above show some interesting facts. On het left you can see the pressure distribution on different locations on a flexible wing, and on the right the same, but then for a rigid wing (thus, not deformed)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that on the right image (around x/c=0.3), there are sharp jumps in the graphs, these indicate shocks, and lead to wave drag. On the flexible side, the gradients are less steep, meaning the shock wave is less strong. As a consequence the wave drag will be less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, based on these graphs, we can conclude that the flexible wing will have less wave drag, than the same wing that would not deform.  &lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-08-20T11:34:42.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19137" PostTypeId="2" ParentId="19123" CreationDate="2015-08-20T12:01:53.430" Score="4" Body="&lt;p&gt;The pivot wing, also called oblique wing is a type of wing design that tries to minimize the drag over the entire speed range of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low speeds, the main concern is the induced drag, which can be reduced by increasing the aspect ratio. That is why low speed aircrafts like gliders have very long slender wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the speed increases, the induced drag falls off quickly and the wave drag comes to dominate at supersonic speeds. This is the reason why supersonic aircrafts have highly swept wings with very small aspect ratios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to reduce the drag at high speeds is to sweep the wing. The velocity component perpendicular to the wing is reduced, reducing the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The delta wing is a highly swept wing used in supersonic combat aircrafts. A good example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt;, which is a tailless delta. The delta wing provides excellent supersonic performance and has a high stall angle. However, the wing 'bleeds' energy rapidly during turns and the requires high takeoff and landing angles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZoXfw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZoXfw.png&quot; alt=&quot;Eurofighter Typhoon&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Eurofighter_Typhoon_line_drawing.svg#/media/File:Eurofighter_Typhoon_line_drawing.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter Typhoon line drawing&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Inductiveload&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Inductiveload&quot;&gt;Inductiveload&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trapezoidal wing is a  version of high speed wing with small aspect ratio. The most famous example of the use of trapezoidal wing was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-104 Starfighter&lt;/a&gt;, which had excellent high speed performance. However, the aircraft had high takeoff and landing speeds and comparatively less low speed performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/arg5g.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/arg5g.png&quot; alt=&quot;F 104 Starfighter&quot;&gt;&lt;/a&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Lockheed_F-104C_Starfighter.svg#/media/File:Lockheed_F-104C_Starfighter.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-104C Starfighter&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Kaboldy&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Kaboldy&quot;&gt;Kaboldy&lt;/a&gt; - Own work. Licensed under GFDL via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all the swept wings in use are swept towards the rear. One disadvantage of this kind of wing is the th airflow is from the root to the tip and as a consequence, the (outboard) ailerons stall before the inboard portion of wing and this results in loss of roll control in high angles of attack. This can be prevented by sweeping the wing forward. However, the bending stress in the wing root is increased due to aeroelastic twisting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aLfQl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aLfQl.jpg&quot; alt=&quot;X 29&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source: NASA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue with fixed sweep wings is that what is efficient in one regime will not be so in the other. One way to reduce the drag in all speeds is to change the sweep and aspect ratio of the wing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The variable sweep wings change the aspect ratio by rotating a part of the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5vuLj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5vuLj.jpg&quot; alt=&quot;F111&quot;&gt;&lt;/a&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Three_F-111s_with_different_wing_configurations.jpg#/media/File:Three_F-111s_with_different_wing_configurations.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Three F-111s with different wing configurations&lt;/a&gt;&quot; by Jason B from Australia - 3 Configs. Licensed under CC BY 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pivot wing is an extreme version of the swept wing where the entire wing is rotated. So far, it has only been implemented in one aircraft, the &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_AD-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA SD-1&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C92FO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C92FO.jpg&quot; alt=&quot;AD 1&quot;&gt;&lt;/a&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:AD-1_ObliqueWing_60deg_19800701.jpg#/media/File:AD-1_ObliqueWing_60deg_19800701.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;AD-1 ObliqueWing 60deg 19800701&lt;/a&gt;&quot; by NASA - &lt;a href=&quot;http://www1.dfrc.nasa.gov/Gallery/Photo/AD-1/HTML/ECN-15846.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www1.dfrc.nasa.gov/Gallery/Photo/AD-1/HTML/ECN-15846.html&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main aerodynamic advantage of the oblique wing is that by adjusting the sweep progressively, the aircrafts can be optimized for drag reduction over a wide range of Mach numbers. Also, the AD-1 was designed with &lt;a href=&quot;https://en.wikipedia.org/wiki/Elliptical_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;elliptical wing&lt;/a&gt; for minimizing induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, on the downside, as the entire wing is rotated, one side of the wing is swept forward, while the other side is swept towards the rear. This means that their stalling characteristics are entirely different. On one side (forward swept side), the inboard region stalls first, while its the opposite on the other side. This makes controlling the aircraft difficult. A follow on project of AD-1, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_Switchblade&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop Grumman Switchblade&lt;/a&gt; was canceled over control difficulties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft also exhibited aeroelastic and pitch-roll coupling effects that adversely affected the aircraft's handling qualities at over 45 degrees sweep.&#xA;Also, the aircraft exhibited unusual trim requirements and inertial coupling. For instance, it was reported tha the &lt;a href=&quot;http://web.archive.org/web/20070614015156/http://www.obliqueflyingwing.com/OWhistory.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AD-1 required&lt;/a&gt; about 10° of bank in order to trim the aircraft with no sideslip at 60° wing sweep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though the pivot wing aircraft had excellent aerodynamic characteristics, its poor and unusual control characteristics prevented further development.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-20T12:01:53.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19138" PostTypeId="2" ParentId="19130" CreationDate="2015-08-20T12:04:14.153" Score="9" Body="&lt;p&gt;Advantages of an oblique wing over swing wings:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Low wave drag due to favorable volume distribution over length.&lt;/li&gt;&#xA;&lt;li&gt;Lower structural mass. The hinge of a swing wing is heavy!&lt;/li&gt;&#xA;&lt;li&gt;No shift in the center of lift (if the sweep angle is higher than the Mach angle). A swing wing experiences a severe shift in the center of lift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Disadvantages of an oblique wing over a swing wing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One wing is swept forward, the other aft. This is no problem in straight flight, but when maneuvering, it will behave in odd ways because the axes of its inertial system are not aligned with the direction of flight.&lt;/li&gt;&#xA;&lt;li&gt;Aeroelasticity: Gust response when flying oblique will include a roll answer, because the forward-swept wing will twist to a higher angle of attack in a positive gust, increasing lift, whereas the backward swept wing will twist to a lower angle of attack (aeroelastic washout).&lt;/li&gt;&#xA;&lt;li&gt;Wing-airframe integration is complex, and the wing needs to be on top of the fuselage (unless you have a flying wing; then the disadvantage is a really small payload volume). The swing wing needs much space for the hinge, spar carry-through and actuation, but can be placed anywhere you like.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that all other effects which plague the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2360/what-are-the-advantages-of-a-forward-swept-wing-over-a-rearward-swept-wing/12855?s=7%7C0.2143#12855&quot;&gt;forward-swept wing&lt;/a&gt; apply here, too, but only on one side. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitch-up&quot; rel=&quot;nofollow noreferrer&quot;&gt;effect of boundary layer thickening&lt;/a&gt; will only happen on the backward-swept side, so changing the angle of attack will already create a rolling moment. The oblique wing will only behave normally when set at a sweep angle of 0°.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-20T12:13:12.290" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19139" PostTypeId="2" ParentId="19130" CreationDate="2015-08-20T12:57:51.583" Score="10" Body="&lt;p&gt;The oblique wing and the swing wing aim to reduce the drag over a wide range of speeds by changing the wing sweep. While the swing wing rotates a part of the wing to achieve this, the oblique wing rotates the whole wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first production aircraft with variable sweep wings was the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;nofollow noreferrer&quot;&gt;F111 Aardvark&lt;/a&gt;, while the most famous one is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_F-14_Tomcat&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-14 Tomcat&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uwpxa.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uwpxa.jpg&quot; alt=&quot;F 14 prototypes in flight&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-14_Tomcat_prototypes_in_flight_c1972.jpg#/media/File:F-14_Tomcat_prototypes_in_flight_c1972.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-14 Tomcat prototypes in flight c1972&lt;/a&gt;&quot; by U.S. Navy - U.S. Navy National Museum of Naval Aviation photo No. 2011.003.301.027. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the only full sized aircraft to be produced with an oblique or pivot wing was the &lt;a href=&quot;https://en.wikipedia.org/wiki/NASA_AD-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA AD-1&lt;/a&gt;, which was strictly an experimental aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6nkh2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6nkh2.jpg&quot; alt=&quot;AD 1&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:AD-1_ObliqueWing_60deg_19800701.jpg#/media/File:AD-1_ObliqueWing_60deg_19800701.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;AD-1 ObliqueWing 60deg 19800701&lt;/a&gt;&quot; by NASA - &lt;a href=&quot;http://www1.dfrc.nasa.gov/Gallery/Photo/AD-1/HTML/ECN-15846.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www1.dfrc.nasa.gov/Gallery/Photo/AD-1/HTML/ECN-15846.html&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A comparison between the two can be made like this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Aerodynamics:&lt;/strong&gt; The oblique wing is much more refined aerodynamically compared to the swing wing and had lesser drag. In fact the AD-1 was designed to be as close to the optimal for all the flight regimes. Also, the aircraft was designed to have an elliptical lift distribution to reduce induced drag. on the other hand, the variable geometry aircraft did not offer any significant advantages over fixed wing baseline aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;However, the asymmetric stall of the oblique wing aircraft would cause problems as one side of the wing is swept forwards and the other side is swept towards the rear.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;strong&gt;Structure:&lt;/strong&gt; The hinge was arguably the most critical structural part in variable sweep wing aircraft. The hinge should not only have a very high reliability, but also have the capacity to bear the high aerodynamic loads. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vTkky.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vTkky.jpg&quot; alt=&quot;Panavia Tornado Hinge&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Tornado_variable_sweep_wing_Manching.JPG#/media/File:Tornado_variable_sweep_wing_Manching.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tornado variable sweep wing Manching&lt;/a&gt;&quot; by Sovxx - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the swing wing aircraft are better off compared to the oblique wing aircraft as the amount of load on the hinge is significantly lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the oblique wing hinge has to take not only the weight of the entire aircraft wing (the swing wing aircraft typically rotate only a part of the wing), but also the entire fuel load (the amount of fuel carried in the variable part of the wing is significantly small). Also, the hinge should take the load of the control system too.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;&lt;strong&gt;Handling and Controls:&lt;/strong&gt; The handling of the swing wing aircraft have been brought closer to the fixed wing aircraft over time. However,the handling qualities of AD-1 was found to be poor, with unusual trim requirements and inertial coupling affecting the &lt;a href=&quot;http://web.archive.org/web/20070614015156/http://www.obliqueflyingwing.com/OWhistory.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft negatively&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;For instance, the AD-1 required about 10° of bank in order to trim the aircraft with no sideslip at 60° wing sweep.The aircraft also experienced pitch-roll coupling and the associated aeroelastic effects made for unpleasant handling qualities above 45 degrees sweep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One advantage of the oblique wing aircraft is that the center of lift and mass doesn't move as the wings are swept. This happens in the swing wing aircraft and the control system is complicated &lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;4&quot;&gt;&#xA;&lt;li&gt;&lt;strong&gt;Engine and payload&lt;/strong&gt; In case of swing wing aircraft, the engines can be mounted in the fuselage (like F-14) or in the (fixed part of) wing itself (like B-1). In case of the oblique wing aircraft, locating the engines anywhere except the fuselage is effectively ruled out.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In case of military aircraft, use of hardpoints in the variable point of the wing is limited (for one thing, this will increase the load on the hinge). This is a much more serious problem for oblique wing aircraft as this limits the payload that could be carried.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the main reason for the lack of further development of oblique wing aircraft is their unusual and unpleasant control qualities.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-09-03T20:26:53.043" LastActivityDate="2015-09-03T20:26:53.043" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19140" PostTypeId="1" AcceptedAnswerId="19146" CreationDate="2015-08-20T13:03:29.740" Score="10" ViewCount="2986" Body="&lt;p&gt;It is my understanding that these aircraft rarely fly at supersonic speeds anyway—the ordnance they carry, the increased fuel burn (even with supercruise), and the increased chance of detection make supersonic flight either hard to maintain or seem unnecessary. In addition, it would seem more beneficial to perform subsonic evasive maneuvers against an incoming missile than to try to outrun it (many air-to-air missiles fly at Mach 3 or higher). Finally, the subsonic Sea Harrier even downed a supersonic-capable Mirage III and many supersonic-capable IAI Daggers to no losses during the Falklands War. Though this can be attributed to the superior pilot training and offensive technology of the Harriers, how come many other aircraft were/are produced with a supersonic requirement?&lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="1696" LastEditDate="2018-04-13T23:49:37.717" LastActivityDate="2020-04-28T11:14:09.943" Title="Why are many military fighter aircraft designed to fly supersonic?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;supersonic&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19141" PostTypeId="2" ParentId="19135" CreationDate="2015-08-20T13:21:45.243" Score="5" Body="&lt;p&gt;The main advantages of the ruddervators (or V-tails are)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They are typically lighter and have less wetted surface area compared to the conventional tail configuration as it has one control surface less (though this reduction is not as simple as reducing one third). As a result the drag is reduced.&lt;/li&gt;&#xA;&lt;li&gt;They are used in some cases to increase stealth. The canted surfaces reflect the radar away from the source, aiding in stealth. They also allow the engine to be mounted above the fuselage (like &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_RQ-4_Global_Hawk&quot; rel=&quot;noreferrer&quot;&gt;Global Hawk&lt;/a&gt;), reducing the infrared signature from below.&lt;/li&gt;&#xA;&lt;li&gt;In &lt;a href=&quot;http://cirrusaircraft.com/aircraft/vision-sf50/&quot; rel=&quot;noreferrer&quot;&gt;Cirrus SJ50&lt;/a&gt;, the 'V' tail is used to allow engine placement above and outside the fuselage,which is claimed to improve safety and reduce cabin noise.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main disadvantages are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They require a much more complex control system compared to the conventional aircrafts as both the surfaces have to be move together.&lt;/li&gt;&#xA;&lt;li&gt;They are required to be structurally more robust compared to the conventional system due to the increased load involved. This reduces the advantage gained by eliminating a control surface.&lt;/li&gt;&#xA;&lt;li&gt;The amount of control forces required for operating the ruddervators are higher compared to the conventional ones and in some cases, it may be more.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-20T13:21:45.243" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19142" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T13:23:53.193" Score="8" Body="&lt;p&gt;In theory, yes, inefficient, very very unstable, with the control surfaces facing the airflow rather than behind it so a big risk of the airflow snatching the controls and forcing them over to full travel - with very bad results. The aeroplane would want to flick round and fly in the opposite direction because of the way its designed to fly forwards.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-20T13:23:53.193" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19143" PostTypeId="5" CreationDate="2015-08-20T13:31:14.660" Score="0" Body="&lt;p&gt;The see-and-avoid method requires that pilots actively search for other traffic by visually scaning outside the aircraft, gather information relative to other aircraft from radio transmissions and take proper action to avoid other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When weather conditions permit, regardless of whether an operation is conducted under instrument flight rules or visual flight rules, vigilance shall be maintained by each person operating an aircraft so as to see and avoid other aircraft. When an other aircraft has the right-of-way, the pilot shall give way to that aircraft and may not pass over, under, or ahead of it unless well clear.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2015-08-20T13:44:29.300" LastActivityDate="2015-08-20T13:44:29.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19144" PostTypeId="4" CreationDate="2015-08-20T13:31:14.660" Score="0" Body="A method for avoiding collision in VMC." OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2015-08-20T13:44:35.730" LastActivityDate="2015-08-20T13:44:35.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19145" PostTypeId="2" ParentId="19135" CreationDate="2015-08-20T13:49:23.223" Score="6" Body="&lt;p&gt;&lt;strong&gt;More induced drag&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A disadvantage (especially critical during landing) is that there is more induced drag to make certain movements.&#xA;The image below helps to understand this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TB6x5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TB6x5.jpg&quot; alt=&quot;Ruddervator movements&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/emp.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To yaw, you have to use both ruddervators (contrary to just a single rudder movement for a normal tail). This is done in order to compensate the unwanted vertical component. This leads to increased induced drag, which is a big problem during take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Less interference drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number of intersections goes down. In the case of a conventional tail you have three intersections (fuselage - left elevator, fuselage - rudder, fuselage - right elevator), whereas for a V-tail you only have two (fuselage - left ruddervator, fuselage - right ruddervator). This reduces the interference drag.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-08-21T07:59:41.200" LastActivityDate="2015-08-21T07:59:41.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19146" PostTypeId="2" ParentId="19140" CreationDate="2015-08-20T14:02:16.407" Score="14" Body="&lt;p&gt;One reason is interception (with interceptor, not missiles).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Defence is probably more important. Defence with fighters is still important for three reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There are relatively effective counter-measures against surface-to-air missiles. A fighter pilot can adjust the strategy to the counter-measures encountered, missile can't.&lt;/li&gt;&#xA;&lt;li&gt;In peace or limited conflict situations it is often not known whether a suspicious target is hostile at all and the only way to identify it is to have a fighter fly to it and have the pilot identify it with their eyes.&lt;/li&gt;&#xA;&lt;li&gt;Fighter can also do other things than use lethal force. In peace time you generally don't want to shot down an intruding military aircraft of another country straight away. Fighter can chase it away from your territory or can try to arrest it (force it to land on your own airbase). And fighters are also used to identify and possibly navigate to safety civil aircraft that lost radio contact.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So when a potentially hostile aircraft is detected entering your territory, fighters are sent to intercept it and help it, arrest it or shot it down depending on what it turns out to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the fighters are slower than the intruder, they may not be able to intercept it at all (they don't usually know where it is flying so they can't wait for it). The faster they are, the larger area they can defend. In this case the interceptors take off without external fuel tanks (as they won't be flying very far) and with only relatively small air-to-air missiles, so they can fly fast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely if you try to penetrate the enemy territory, flying faster limits the number of fighters that can intercept you. However in this case it is more useful to rely on stealth or flying low to evade detection, so attack aircraft often are either not supersonic or have lower maximum speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-08-21T08:40:52.237" LastActivityDate="2015-08-21T08:40:52.237" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19147" PostTypeId="2" ParentId="18725" CreationDate="2015-08-20T14:05:55.937" Score="8" Body="&lt;p&gt;&lt;strong&gt;Reflector Sight:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Me 262 &lt;em&gt;Schwalbe&lt;/em&gt;, introduced in 1944 as the world's first operational jet fighter aircraft, did not have a full-blown HUD. Instead, like many fighters of WWII, it had a reflector sight which used lenses and reflecting glass to display a reticle. &lt;a href=&quot;http://www.strangemilitary.com/images/content/173673.jpg&quot; rel=&quot;noreferrer&quot;&gt;This sort of thing&lt;/a&gt; [all of the bright yellow lines you see in the image are fixed together. Although you only really needed a dot and a circle (like the Spitfire), some pilots liked the extra lines to help line up targets that were not dead-ahead. They were favored by pilots over iron-sights because the pilot was not required to position his head in order to see where the guns would fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Simple HUD&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MiG-21, introduced in 1959, used a combination of reflector sight and HUD. Though it didn't display the altitude, speed, heading, or attitude in a way that modern fighter pilots may take for granted, it had some ability to track targets with radar and to display predicted target positions for gun or missile use. Here is a &lt;a href=&quot;http://s50.radikal.ru/i129/0912/2f/7f7c5d1d1a46.jpg&quot; rel=&quot;noreferrer&quot;&gt;guide&lt;/a&gt; on how to aim your guns using its sight. Also, &lt;a href=&quot;http://s56.radikal.ru/i153/0912/49/ed4ef515cad4.jpg&quot; rel=&quot;noreferrer&quot;&gt;explanations&lt;/a&gt; of the displays. The following image was posted on a &lt;a href=&quot;http://combatace.com/topic/42961-mig-23-cockpit-series-almost-finished-with-working-mig-23hud/&quot; rel=&quot;noreferrer&quot;&gt;forum thread&lt;/a&gt; related to the MiG-23, which came after the MiG-21, but this &lt;a href=&quot;http://backfiretu-22m.tripod.com/sitebuildercontent/sitebuilderpictures/f117.jpg&quot; rel=&quot;noreferrer&quot;&gt;image&lt;/a&gt; looks much like those from the MiG-21 manual. A different &lt;a href=&quot;http://farm2.static.flickr.com/1240/1223858504_701158d1d5.jpg&quot; rel=&quot;noreferrer&quot;&gt;image&lt;/a&gt; from another &lt;a href=&quot;http://www.flickriver.com/photos/53995653@N00/popular-interesting/&quot; rel=&quot;noreferrer&quot;&gt;author&lt;/a&gt; shows you how simple the display could get. Finally, an &lt;a href=&quot;http://www.militaryimages.net/photopost/data/520/F-161.jpg&quot; rel=&quot;noreferrer&quot;&gt;F-16 in the sights of a MiG-21&lt;/a&gt;. You can tell this is a MiG because of the distinctive &lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/101-200/awa153-Mig21MF/images%20Percy%20Olson/MiG-21J_Intake_and_pitot_tube.jpg&quot; rel=&quot;noreferrer&quot;&gt;pitot tube&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Full HUD&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-14 first flew in 1970. Its &lt;a href=&quot;http://www.topedge.com/panels/aircraft/sites/mats/f14-detail-cp-d-hud.gif&quot; rel=&quot;noreferrer&quot;&gt;HUD&lt;/a&gt; was equipped with an artificial horizon, altitude, speed, heading, gun data, missile data, and much more. &lt;a href=&quot;http://www.pushing-pixels.org/wp-content/uploads/2012/06/mig-29_f_18_gun_camera.jpg&quot; rel=&quot;noreferrer&quot;&gt;This&lt;/a&gt; is from the F/A-18, which first flew almost a decade later.&lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="9875" LastEditDate="2015-08-21T17:55:48.440" LastActivityDate="2015-08-21T17:55:48.440" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19148" PostTypeId="2" ParentId="19039" CreationDate="2015-08-20T14:38:49.563" Score="0" Body="&lt;p&gt;Yes, there have certainly been cases in which fighter pilots break bones while performing high-G turns. Unfortunately, the bone most susceptible to injury is the &lt;a href=&quot;https://books.google.com/books?id=LXuMaPb0RAIC&amp;amp;pg=PA79&amp;amp;lpg=PA79&amp;amp;dq=air+combat+maneuvering+injuries&amp;amp;source=bl&amp;amp;ots=eBiU0rR0X4&amp;amp;sig=fq2_ckB_UEwYYvyqG_P6TtVeSyw&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0CFEQ6AEwCGoVChMI0cXa2e63xwIVUA-SCh3sQAP2#v=onepage&amp;amp;q=air%20combat&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;spine&lt;/a&gt; because that is the one of the few structures supporting real weight other than itself.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...pilots of high-performance aircraft frequently sustained cervical spine injuries due to their exposure to high gravitational forces (5), these investigators measured accelerations about the head of an F-16 fighter pilot during simulated air combat maneuvers. With the aid of a spine model, they calculated the forces on the lower cervical spine and noted that the forces were of the same order of magnitude as failure loads of cervical vertebrae and estimations of maximum cervical spine muscle forces.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In one miraculous instance, a USAF pilot was able to land after pulling a 9G turn and breaking his back. I currently cannot find a source for this but I remember listening to my dad's friends (USN) talk about visiting the pilot. I believe he was disabled in a leg or maybe both but he did not fly again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Less severe maneuvering will not break bones very easily, but they can produce &lt;a href=&quot;http://www.ncbi.nlm.nih.gov/pubmed/9184740&quot; rel=&quot;nofollow&quot;&gt;neck injuries&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many safety features built into aircraft that can maneuver into such high-G turns, however. The earliest example of this is the G-suit, which pushes blood that pools in the lower half of the body back up to the brain using air pressure lines and sacs. In addition, some aircraft set artificial limits on how tight a pilot can turn to prevent pilot injury and airframe stress (The F-14 could survive much more than 6-7Gs but that limit was set on the controls to reduce wing stress and failure). More recently aircraft have adopted digital systems that will right an aircraft if the pilot fails to respond to an alarm within a certain period of time. If a pilot is in blackout or prolonged greyout, the aircraft ignores pilot input and tries to fly straight and level. This is mainly to prevent unconscious crashes into terrain, but it also prevents pilots from entering tighter and tighter turns that they cannot leave.&lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="9875" LastEditDate="2015-08-20T14:51:06.760" LastActivityDate="2015-08-20T14:51:06.760" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19149" PostTypeId="1" AcceptedAnswerId="19150" CreationDate="2015-08-20T14:39:16.117" Score="7" ViewCount="1333" Body="&lt;p&gt;When using a runway, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8812/what-determines-in-which-direction-a-runway-is-used&quot;&gt;many factors are taken into account to choose the landing direction&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lake can be used in almost any direction by seaplanes. I imagine wind is prevalent, but I guess other elements such as waves, form of the body of water surface, water flow should also be taken into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the elements taken into account when choosing the direction to land a seaplane onto a body of water, and how do thoses elements influence the direction?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-20T15:00:51.073" Title="How is the direction chosen when landing a seaplane on water?" Tags="&lt;landing&gt;&lt;seaplane&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19150" PostTypeId="2" ParentId="19149" CreationDate="2015-08-20T15:00:51.073" Score="6" Body="&lt;p&gt;Here is a &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/seaplanes/landings.htm&quot;&gt;nice little article&lt;/a&gt; on it. But in general the small waves on the water will curl with the wind and can even be used as a wind indicator. For calm water you can obviously chose your direction based largely on wind (but if the water is very calm there is likely little wind). Obstructions will play into choosing direction as well and it is advised to overfly the intended landing area before touching down. As for rough water landings the article states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is impractical to describe an ideal rough water procedure because of the varying conditions of the surface. In most instances, though, the approach is made the same as for any other water landing. It may be better however, to level off just above the water surface and increase the power sufficiently to maintain a rather flat attitude until conditions appear more acceptable&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Your elements are (in no particular order)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstacles &lt;/li&gt;&#xA;&lt;li&gt;Wind&lt;/li&gt;&#xA;&lt;li&gt;Landing Area (you need enough distance to actually land same as a paved strip)&lt;/li&gt;&#xA;&lt;li&gt;Possible Rough Conditions &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You must also keep in mind where you &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2008/April/3/New-SPA-Water-Landing-Directory-is-seaplane-friendly&quot;&gt;can actually land a seaplane&lt;/a&gt;. Not every body of water is legal to land a sea plane in (emergencies aside). You may want to check out &lt;a href=&quot;http://generalaviationnews.com/2015/08/20/new-book-commemorates-anniversary-of-floatplane-odyssey/&quot;&gt;this recently released book&lt;/a&gt; on arguable the first guy that flew a seaplane around the world. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-08-20T15:00:51.073" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19151" PostTypeId="1" AcceptedAnswerId="19155" CreationDate="2015-08-20T15:25:22.107" Score="1" ViewCount="1288" Body="&lt;p&gt;The A320neo has a 16% higher market share, 1022 more orders, 316 more MoU's and $122.1 bn greater estimated value than the B737Max. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though both were released at almost the same time (231 days gap) with identical features and price (rather B737Max is  $15 mn cheaper), why is the A320 flying past the B737?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Data source : &lt;a href=&quot;http://www.pdxlight.com/neomax.htm&quot; rel=&quot;nofollow&quot;&gt;PDXLight&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-08-21T16:07:50.043" LastActivityDate="2015-08-21T16:07:50.043" Title="Why is the A320neo considerably ahead of B737Max?" Tags="&lt;airbus-a320&gt;&lt;boeing-737&gt;&lt;aircraft-order&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19152" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T15:43:38.390" Score="2" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try riding your bicycle backwards down a steep hill if you are not sure what other writers here mean by passive pitch stability and yaw stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason why the big tail and elevators are well behind the middle of the wings is to make sure that when flying forward, they will tend to straighten any wobble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Go to the pub and have a look at how darts fly if you want.  You can try throwing one of those backwards too. &lt;/p&gt;&#xA;" OwnerUserId="9889" LastActivityDate="2015-08-20T15:43:38.390" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19153" PostTypeId="2" ParentId="19151" CreationDate="2015-08-20T15:57:23.180" Score="2" Body="&lt;p&gt;The 231 days gap is a big factor. Some airlines will want their planes sooner rather than later, which means the first one to the market will have an advantage. There is more than 231 days of gap between their entries into service. So if airlines are ordering planes out to, say, 2020, then naturally the type introduced earlier will have more orders. A graph from the linked source shows the number of orders based on days since launch. The A320 still comes out ahead of the 737, but the difference is not as dramatic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the list prices are similar, no one will actually pay those prices. Both Boeing and Airbus will negotiate heavily with their customers to secure sales at much lower prices. The prices actually agreed to are typically not published, but it's possible that one factor is that Airbus is willing to give more of a discount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Features are also not really identical. They may be very similar on the outside, but each manufacturer will tell you about the features that distinguish their product from the competition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important factor is where the orders are coming from. Asia is a rapidly growing market, and the map shows that Airbus has received far more orders there. &lt;a href=&quot;http://www.airbus.com/innovation/proven-concepts/in-manufacturing/final-assembly-lines/&quot; rel=&quot;nofollow&quot;&gt;Airbus has an assembly line in China&lt;/a&gt;, which could be another factor working in their favor.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-08-20T15:57:23.180" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19155" PostTypeId="2" ParentId="19151" CreationDate="2015-08-20T18:06:17.880" Score="4" Body="&lt;p&gt;I certainly would not say that the 737 MAX is &quot;losing heavily&quot; to the A320neo. The A320neo is entering service in the next couple of months (October 2015.) The 737 MAX isn't entering service for another 2 years (2017.) I don't think many aircraft manufacturers would be upset with having &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Boeing_737_MAX_orders&quot; rel=&quot;nofollow&quot;&gt;2,727 orders&lt;/a&gt; for an aircraft that is still 2 years from even entering service. It should further be noted that the A320neo was right around the same total when it was 2 years from entering service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some additional factors that come into play:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The A320 line tends to be more popular in the low-budget Asian market, which is growing significantly right now.&lt;/li&gt;&#xA;&lt;li&gt;The U.S. Dollar is currently relatively strong compared to the Euro, due to lots of economic problems in the Eurozone. This means that products exported by European manufacturers are relatively cheaper than products exported by American manufacturers compared to their usual price difference. Obviously, that's an advantage for Airbus, as it means that it's cheaper than normal right now for customers to buy Airbus vs. buying Boeing. This is, again, especially important to the cost-sensitive low-budget markets.&lt;/li&gt;&#xA;&lt;li&gt;Airbus' Chinese assembly line allows them to make A320s for the Asian market quite a bit cheaper than Boeing can make 737s for that market, due to the major differences in labor costs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-08-20T18:06:17.880" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19156" PostTypeId="1" AcceptedAnswerId="19159" CreationDate="2015-08-20T18:39:23.907" Score="4" ViewCount="5334" Body="&lt;p&gt;While in cruise, without GPS how does a pilot know the wind direction? The airspeed sensors only register forward speed. Is it a matter of reaching waypoints sooner or later? And if flying on a compass heading how do they know what their ground track is and whether or not they're being blown off course? Especially with no visual reference.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-21T01:08:19.760" Title="How does a pilot know if he has headwind, tailwind or crosswind?" Tags="&lt;navigation&gt;&lt;sensors&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19157" PostTypeId="1" AcceptedAnswerId="19158" CreationDate="2015-08-20T18:48:04.140" Score="18" ViewCount="17186" Body="&lt;p&gt;In some multi seat fighters, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;F-111 Aardvark&lt;/a&gt; the pilots sit next to each other, like so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LKZPf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LKZPf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While in other multi seat fighters (most of them it seems) the pilots sit with one in front of the other, like this &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15E_Strike_Eagle&quot; rel=&quot;noreferrer&quot;&gt;F-15E&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VEawu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VEawu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do some fighters have the pilots in a line like that?  Is there an aerodynamic or performance advantage that comes with having them in a line?  Or maybe it's so they can have a bubble canopy, which perhaps affords a better view? It seems it would be easier to work together when they are side by side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why do some multi seat fighters have side by side seating, and others are in a line?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="7532" LastEditDate="2017-05-15T19:36:35.763" LastActivityDate="2020-11-07T10:54:00.247" Title="Why do some 2 seat fighters have side by side seating, while others have the pilots inline with each other?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;seats&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19158" PostTypeId="2" ParentId="19157" CreationDate="2015-08-20T19:28:16.817" Score="22" Body="&lt;p&gt;The tandem arrangement (one behind the other) is used on aircraft that have single seat variants. The F-15, F-16, and F/A-18 are all primarily single seat aircraft. It's much easier to stretch the nose out a bit to add a second position than to make it wider. This arrangement is also more aerodynamic, requiring less frontal area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter aircraft designed for a crew of two will often choose the tandem arrangement for aerodynamics. If both seats need forward visibility, &lt;a href=&quot;http://www.sr-71.org/photogallery/blackbird/17956/&quot;&gt;there are compromises available&lt;/a&gt;. Some aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15E_Strike_Eagle&quot;&gt;F-15E&lt;/a&gt; can be flown from both seats even though there is less visibility from the back. It's possible to have a bubble canopy in side-by-side configuration (this is particularly seen in &lt;a href=&quot;https://en.wikipedia.org/wiki/AMD_Zodiac&quot;&gt;aircraft kits&lt;/a&gt;), though it will create more drag than a tandem canopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the crew sit next to each other can be helpful for crew interaction and sharing instrumentation. &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot;&gt;The F-111 is one such special case&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The USAF wanted a tandem-seat aircraft for low-level penetration ground-attack, while the Navy wanted a shorter, high altitude interceptor with side-by-side seating to allow the pilot and RIO to share the radar display.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This may have also been easier to design the escape capsule. Of course the Navy changed their mind and went with the F-14 instead for better maneuverability.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-08-21T15:05:34.203" LastActivityDate="2015-08-21T15:05:34.203" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19159" PostTypeId="2" ParentId="19156" CreationDate="2015-08-20T19:33:10.313" Score="7" Body="&lt;p&gt;With no visual or instrument references you &lt;em&gt;don't&lt;/em&gt; know if you have a headwind, tailwind, or crosswind.&lt;br&gt;&#xA;You also don't particularly care because &lt;em&gt;you're flying a plane with no way to navigate&lt;/em&gt; and therefore have more imperative concerns.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;With visual references it's something you can determine with a little thinking and some intentional oversimplification:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Headwinds&lt;/strong&gt; mean your ground speed is &lt;em&gt;lower&lt;/em&gt; than your airspeed.&lt;br&gt;&#xA;If your airspeed is 100 miles per hour and you're flying a 25 mile leg it should take you 15 minutes. If it takes you 18 minutes you know you've got a headwind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Tailwnds&lt;/strong&gt; mean your gound speed is &lt;em&gt;higher&lt;/em&gt; than your airspeed.&lt;br&gt;&#xA;If you're flying the same 25 mile leg at 100 miles per hour and it only takes you 12 minutes you have a tailwind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Crosswinds&lt;/strong&gt; are a bit more difficult: The easiest way to tell you have a crosswind is if you know what your magnetic heading &lt;em&gt;should&lt;/em&gt; be in order to fly toward a given point and you have to point the nose at a different compass heading in order to maintain the desired ground track you have a crosswind. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that you almost never have a &lt;em&gt;direct&lt;/em&gt; headwind, tailwind, or crosswind, but rather some wind at an angle to your direction of travel which will have both a crosswind component and a headwind/tailwind component. The wind speed and direction can be computed using &lt;a href=&quot;https://en.wikipedia.org/wiki/E6B&quot;&gt;an E6B flight computer&lt;/a&gt; with relatively little effort.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you have instrument references the problem gets easier:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;GPS&lt;/strong&gt; is the ultimate solution -- it can display your ground speed and ground track, from which you can derive the winds. GPS systems that know your airspeed can even calculate the winds for you so you don't need the E6B anymore (unless the GPS breaks).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;VORs&lt;/strong&gt; provide a magnetic heading reference, which simplifies the crosswind calculation (and largely eliminates the need to do one to figure out your crosswind correction angle: Just keep the needle centered and you have your desired crosswind correction).&lt;br&gt;&#xA;It doesn't give you the wind speed and direction without some additional data (how long it takes you to cross some waypoint or fix), because you still need that information in order to determine how much of the wind speed is acting as a headwind, tailwind, or crosswind component.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;DME systems&lt;/strong&gt; can give you your groundspeed. In combination with the VOR this gives you the same information as the GPS and makes determining the wind speed pretty simple.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;ADFs&lt;/strong&gt; can be used for this kind of calculation in the same way as you would for a visual waypoint: If you expect to be flying due north to head toward an ADF beacon and you're flying 010 degrees to keep the pointer needle where you want it then you know you're dealing with some crosswind component.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-20T19:33:10.313" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19161" PostTypeId="2" ParentId="19114" CreationDate="2015-08-20T20:19:40.477" Score="2" Body="&lt;p&gt;You don't need reverse thrust to do this. Just pull the nose way up, and let the speed bleed off until your vertical speed is zero. Then you &lt;em&gt;tailslide&lt;/em&gt;.&#xA;Most planes are designed to make this not very easy to do, but if you move the CG far enough back, by putting bricks in the tail, you can do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trouble with that is, unless your plane is specially made, and you are specially trained, you will have a very difficult time not just sliding all the way to the ground (and voiding the warranty).&lt;/p&gt;&#xA;" OwnerUserId="395" LastEditorUserId="395" LastEditDate="2015-08-21T00:52:41.143" LastActivityDate="2015-08-21T00:52:41.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19162" PostTypeId="1" AcceptedAnswerId="19163" CreationDate="2015-08-20T23:14:06.233" Score="0" ViewCount="187" Body="&lt;p&gt;I was wondering if anyone knows how I can get flight data in mass.  Specifically, I'm looking for price, time, and airports involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you know where Google, Expedia, and the likes get their flight information from?&lt;/p&gt;&#xA;" OwnerUserId="9893" LastActivityDate="2015-08-20T23:24:18.703" Title="Where does Google Flights get its pricing information?" Tags="&lt;datasets&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-21T03:38:02.437" ContentLicense="CC BY-SA 3.0" />
  <row Id="19163" PostTypeId="2" ParentId="19162" CreationDate="2015-08-20T23:24:18.703" Score="3" Body="&lt;p&gt;Google bought an airline pricing optimization &#xA;company called ITA Software that has interfaces with the GDS systems.  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-20T23:24:18.703" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19164" PostTypeId="2" ParentId="19157" CreationDate="2015-08-20T23:29:53.577" Score="9" Body="&lt;p&gt;The main reason for having tandem seating in fighter aircrafts is that it offers better performance compared to the side by side version. This is why most of the high performance fighters have tandem seating arrangement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wqxTT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wqxTT.jpg&quot; alt=&quot;Su 30&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Sukhoi_Su-30LL_demonstrator_flying_along_the_runway_at_Zhangjiajie_Hehua_Airport_less_than_1_metre_off_the_ground.jpg#/media/File:Sukhoi_Su-30LL_demonstrator_flying_along_the_runway_at_Zhangjiajie_Hehua_Airport_less_than_1_metre_off_the_ground.jpg&quot; rel=&quot;noreferrer&quot;&gt;Sukhoi Su-30LL demonstrator flying along the runway at Zhangjiajie Hehua Airport less than 1 metre off the ground&lt;/a&gt;&quot;&lt;br&gt;by Xu Zheng - &lt;a href=&quot;http://www.airliners.net/photo/Russia---Air/Sukhoi-Su-30LL/1025605/L/&quot; rel=&quot;noreferrer&quot;&gt;http://www.airliners.net/photo/Russia---Air/Sukhoi-Su-30LL/1025605/L/&lt;/a&gt;. Licensed under CC BY-SA 4.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage in tandem seating arrangement is that conversion from single to double seat (and vice-versa) variant is relatively easy and requires minimal design change compared to the side by side configuration.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/bCX0a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bCX0a.jpg&quot; alt=&quot;Su 27&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Su-27_05.jpg#/media/File:Su-27_05.jpg&quot; rel=&quot;noreferrer&quot;&gt;Su-27 05&lt;/a&gt;&quot; by Unknown - DefenseImagery.mil ID DD-ST-88-09314. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of the side-by-side seating arrangement is that it allows for better work sharing between the crew and reduces the need for duplication of flight instruments. The crew comfort is also (comparatively) better for long range flights, reducing fatigue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RNeNG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RNeNG.jpg&quot; alt=&quot;Su 34&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Sukhoi_Su-34_at_the_MAKS-2013_(03).jpg#/media/File:Sukhoi_Su-34_at_the_MAKS-2013_(03).jpg&quot; rel=&quot;noreferrer&quot;&gt;Sukhoi Su-34 at the MAKS-2013 (03)&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Doomych&quot; rel=&quot;noreferrer&quot; title=&quot;User:Doomych&quot;&gt;Doomych&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the customers (Air Force/Navy) may also decide which arrangement to use. For example, the initial postwar British trainers used side by side seating as RAF preferred this arrangement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of B-52, the prototypes (and even the initial production aircraft) had a tandem seating arrangement.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Eve92.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eve92.jpg&quot; alt=&quot;YB 52&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;br&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:YB-52sideview.jpg#/media/File:YB-52sideview.jpg&quot; rel=&quot;noreferrer&quot;&gt;YB-52sideview&lt;/a&gt;&quot; by Original uploader was Sf46 at en.wikipediaLater version(s) were uploaded by Nobunaga24 at en.wikipedia.(Original text: U.S. Air Force) - Transferred from en.wikipedia; Transfer was stated to be made by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Nobunaga24&quot; rel=&quot;noreferrer&quot; title=&quot;User:Nobunaga24&quot;&gt;User:Nobunaga24&lt;/a&gt;.(Original text: USAF Museum Website). Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Gen. LeMay decided that a aside by side arrangement utilizes the copilot better and improved instrumentation and the arrangement was changed from tandem to side by side.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/e1uMj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e1uMj.jpg&quot; alt=&quot;B 52&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;br&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Boeing_B-52D-40-BW_(SN_56-0695)_and_GAM-72_Quail_decoy_missile_and_trailer_061127-F-1234S-010.jpg#/media/File:Boeing_B-52D-40-BW_(SN_56-0695)_and_GAM-72_Quail_decoy_missile_and_trailer_061127-F-1234S-010.jpg&quot; rel=&quot;noreferrer&quot;&gt;Boeing B-52D-40-BW (SN 56-0695) and GAM-72 Quail decoy missile and trailer 061127-F-1234S-010&lt;/a&gt;&quot; by US Goverment. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-21T13:39:16.317" LastActivityDate="2015-08-21T13:39:16.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19165" PostTypeId="1" AcceptedAnswerId="19170" CreationDate="2015-08-20T23:58:39.277" Score="2" ViewCount="1088" Body="&lt;p&gt;&lt;a href=&quot;https://flightaware.com/live/flight/AWE685&quot; rel=&quot;nofollow&quot;&gt;Flight AWE685&lt;/a&gt; goes from Seattle to Philadelphia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is that AWE685 identifier called?  Every flight seems to have a unique name.  I'm trying to learn more about flight data but it's tough when you don't know what terms to Google for more in-depth results.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Apologies if this question doesn't have a simple answer.  I'm trying to learn about HTTP requests, so I'm teaching myself by pulling flight data from websites.  Also, aviation data is new to me, so I don't realize how easy/difficult of a question this is.&lt;/p&gt;&#xA;" OwnerUserId="9893" LastEditorUserId="755" LastEditDate="2015-08-21T00:42:04.100" LastActivityDate="2018-02-27T23:27:40.173" Title="How do I get flight numbers?" Tags="&lt;airline-operations&gt;&lt;datasets&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19166" PostTypeId="2" ParentId="19165" CreationDate="2015-08-21T00:15:03.360" Score="2" Body="&lt;p&gt;It is the 'call sign' of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this particular instance, the first three characters 'AWE' refers to the airline call sign (telephony designator) of the airline, America West Airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next three number refers to the flight number, which is assigned by the airline, usually based on the route. Combined together, these two form an unique identifier and is used in radio transmissions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The list of airline codes can be seen &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airline_codes&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. However, the flight number is decided by the airlines and their website might be a good place to start.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-21T00:15:03.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19170" PostTypeId="2" ParentId="19165" CreationDate="2015-08-21T00:35:41.660" Score="4" Body="&lt;p&gt;These are colloquially called &quot;flight numbers,&quot; though technically that term refers to just the numerical portion. Pretty much all travelers will use this name for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Wikipedia&lt;/a&gt;, the International Air Transport Association (IATA) officially uses the name &quot;flight code&quot; to refer to the whole portion. Unfortunately, &lt;a href=&quot;http://www.iata.org/publications/Pages/ssim.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;the cited IATA document&lt;/a&gt; is behind a paywall, so I can't independently verify that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, the type of flight code in your example is of the ICAO variety and is also being used as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Call_sign&quot; rel=&quot;nofollow noreferrer&quot;&gt;callsign&lt;/a&gt; for that particular flight for radio communication purposes. In the U.S., it is customary to use the airline's callsign plus the flight number as the callsign for a particular flight. Some other countries use the &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_registration&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Registration Code&lt;/a&gt; (commonly called the &quot;tail number&quot;) of the aircraft instead of the airline flight number as the radio callsign. General aviation aircraft (which don't have airline flight numbers) will also normally use their tail number as their callsign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When used as a call sign, a flight code will use the ICAO code for the airline. However, for purposes of airline reservation systems, it's common to see the flight number listed with the airline's (2-letter) IATA code rather than its (3-letter) ICAO code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a flight number is used as a callsign and is spoken on the radio, the airline's callsign will be spoken instead of the letters in the flight number. For example, your example of AWE685 will be pronounced &quot;Cactus Six Eight Five&quot; on the radio, since &quot;Cactus&quot; is the callsign for U.S. Airways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, the use of &quot;AWE&quot; and &quot;Cactus&quot; for U.S. Airways is a relic of when U.S. Airways merged with America West Airlines. They kept the name of U.S. Airways, but the ICAO code and callsign of America West (whose main hub was in Phoenix, AZ, hence the &quot;cactus&quot; callsign.)&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2018-02-27T21:59:03.000" LastActivityDate="2018-02-27T21:59:03.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19172" PostTypeId="2" ParentId="19156" CreationDate="2015-08-21T01:08:19.760" Score="0" Body="&lt;p&gt;In addition to the other answer (which is great) some of this planning happens before the flight leaves the ground. In the flight planning process you can get both &lt;a href=&quot;https://aviationweather.gov/products/nws/winds/&quot; rel=&quot;nofollow&quot;&gt;winds aloft&lt;/a&gt; and winds at various airports in your route via the &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service&quot; rel=&quot;nofollow&quot;&gt;ATIS&lt;/a&gt;. While it is true that winds will change over time (if you are on a long flight) headings are pre calculated with the known winds at the time of departure. If you are planning a very long flight you can check the outlook forecasts (which may not end up being accurate) and plan your headings with those. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once in the air you can listen to the ATIS along your routes to get live winds below you. This is of course assuming you know which airport is beneath (or near) you at a given time. You may also be able to get weather from a &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_service_station&quot; rel=&quot;nofollow&quot;&gt;Flight Service Station&lt;/a&gt; in route or &lt;a href=&quot;http://www.avweb.com/news/avtraining/183268-1.html&quot; rel=&quot;nofollow&quot;&gt;Flight Following&lt;/a&gt; if its provided. Again this is reliant on you knowing where you are, aside from flight following which will actually tell you where you are if its provided. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all assumes you have a functioning 2 way radio. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-08-21T01:08:19.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19173" PostTypeId="1" AcceptedAnswerId="19178" CreationDate="2015-08-21T01:11:23.403" Score="10" ViewCount="1661" Body="&lt;p&gt;I have seen pictures of World War I-era airplanes that have rudders much smaller than today. When did the first rudder come out?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="22726" LastEditDate="2019-09-27T21:26:48.347" LastActivityDate="2019-09-28T17:44:35.767" Title="When was the first rudder on an aircraft used?" Tags="&lt;aviation-history&gt;&lt;rudder&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="19174" PostTypeId="2" ParentId="19173" CreationDate="2015-08-21T01:24:48.253" Score="3" Body="&lt;p&gt;The Wright Flyer had two rudders.  That flew in 1903.  Some of the wright bros. earlier gliders also had rudders ... To test the technology and to determine the optimum size.&lt;/p&gt;&#xA;" OwnerUserId="9823" LastActivityDate="2015-08-21T01:24:48.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19176" PostTypeId="2" ParentId="19140" CreationDate="2015-08-21T02:35:57.870" Score="11" Body="&lt;p&gt;The answer, &lt;em&gt;speed is life&lt;/em&gt;.  While that may seem abbreviated, superior speed gives fighter aircraft far more options to attrite the enemy or to survive another day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following is a limited subset of general reasons why having superior speed would be an advantage, but unfortunately, specifics are beyond the scope of this discussion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pure Speed&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Offensively, speed is necessary to consummate an intercept, although, it often does not require superior speed, as geometry is a far more useful intercept tool.  However, offensively, speed becomes more useful when chasing down a fleeing aircraft, or when flowing to multiple targets.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Defensively, speed can help targeted aircraft bug out, as well as simply increase time to kill so that other friendlies can swoop in and save the day.  You burn far more gas exploding in a fireball than you do dumping fuel into the afterburners!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Power&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the power to go fast is often just as important, if not more important that the ability to go fast.  Those afterburning, fuel guzzling, engines allow fighters to have enormous rates of climbs, and to sustain airspeed through much more dynamic maneuvers than slower, less powerful, aircraft.  Thrust to weight ratio is paramount in a turn rate fight, and, in BFM, the ability to suddenly add a fist full of knots may be the deciding factor between missile giver and missile taker.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-08-21T02:35:57.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19177" PostTypeId="1" CreationDate="2015-08-21T02:38:37.913" Score="4" ViewCount="4882" Body="&lt;p&gt;(Not &lt;a href=&quot;https://aviation.stackexchange.com/q/7568/6886&quot;&gt;company call-signs&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; gives the following guidelines&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Eastbound and northbound flights are traditionally assigned even numbers, while westbound and southbound flights have odd numbers.&lt;/li&gt;&#xA;  &lt;li&gt;Other airlines will use an odd number for an outbound flight and use the next even number for the reverse inbound flight.&lt;/li&gt;&#xA;  &lt;li&gt;For destinations served by multiple flights per day, numbers tend to increase during the day.&lt;/li&gt;&#xA;  &lt;li&gt;Flight numbers of less than three digits are often assigned to long-haul or otherwise premium flights.&lt;/li&gt;&#xA;  &lt;li&gt;Flight number 1 is often used for an airline's &quot;flagship&quot; service.&lt;/li&gt;&#xA;  &lt;li&gt;Four-digit numbers in the range 1000 to 4999 typically represent regional affiliate flights.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;but doesn't give any references (anybody have any?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming these are (generally) true, are there common strategies for how airlines number flights in a 'class'? For example, is there any significance between DAL310 and DAL342? AAL4569 and AAL4135?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is the standard method generating a (bounded) random number?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-21T16:28:58.417" Title="How do airlines assign flight numbers?" Tags="&lt;airline-operations&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-08-21T17:44:40.250" ContentLicense="CC BY-SA 3.0" />
  <row Id="19178" PostTypeId="2" ParentId="19173" CreationDate="2015-08-21T03:29:05.297" Score="6" Body="&lt;p&gt;Planes as early as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_Glider&quot; rel=&quot;nofollow noreferrer&quot;&gt;wright glider (1902)&lt;/a&gt; had a rudder, it appears from pictures that the 1900 and 1901 variants did not have rudders but its hard to tell from the photos. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZIGT5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZIGT5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on your definition if you are talking about powered flight the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_Flyer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wright Flyer (1903)&lt;/a&gt; had 2 rudders much like its earlier glider predecessor. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1ouUj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1ouUj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the lighter than air category, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Giffard_dirigible&quot; rel=&quot;nofollow noreferrer&quot;&gt;Giffard Dirigible (1852)&lt;/a&gt; had a sail like rudder in the aft of the ship. So that may take the cake if you have consider it a true rudder.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FRMNl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FRMNl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side Note: Patented in &lt;a href=&quot;https://en.wikipedia.org/wiki/V-tail&quot; rel=&quot;nofollow noreferrer&quot;&gt;1930 the V-Tail design&lt;/a&gt; could be argued as the first design that &lt;em&gt;did not&lt;/em&gt; (as far as I know) employ a rudder. The earlier &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beechcraft Bonanza's&lt;/a&gt; are the most common plane of that design in commercial production. There is quite a bit of &lt;a href=&quot;http://karlenepetitt.blogspot.com/2013/09/v-tail-bonanza-debate-is-on.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;debate&lt;/a&gt; as to the safety of ruddervators and the general theme seems to be that they are not perfect and do require some care to fly properly. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-21T13:29:28.597" LastActivityDate="2015-08-21T13:29:28.597" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19179" PostTypeId="2" ParentId="19050" CreationDate="2015-08-21T05:06:14.350" Score="11" Body="&lt;p&gt;This function is provided by the parking brake valve which is an electrically-operated hydraulic valve that, when the parking brake is commanded to be set, closes and traps hydraulic pressure in the brake lines. You set the parking brake by pushing both brake pedals all the way down, and then pulling up on a separate lever that locks the pedals in the applied position and at the same time commands the parking brake valve to close and trap the hydraulic fluid. You can then take your feet off the brake pedals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's no electrical power, that valve can't close. If there's electrical power, but no hydraulic power from the pumps, that valve can close, and the hydraulic pressure to hold the brakes is then supplied by the accumulator. But that's not as reliable as having the hydraulic pumps operating, and you're not assured that the pressure supplied by the accumulator is sufficient to prevent airplane movement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, closing the parking brake valve doesn't ensure a perfectly sealed system. Over time, internal leakage will mean that, if hydraulic power isn't constantly supplied, the trapped brake pressure will gradually leak to the point that the brakes can't hold the airplane, even though the parking brake lever and the brake pedals in the flight deck are still locked.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastActivityDate="2015-08-21T05:06:14.350" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19180" PostTypeId="2" ParentId="18951" CreationDate="2015-08-21T05:19:17.150" Score="38" Body="&lt;p&gt;With the gear handle in the UP position, the retraction side of the landing gear actuators remain pressurized. The gear will stay in the full up position, however they will not be hanging on the mechanical locks designed to hold them in the up position. They've simply hit the full up mechanical stop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the handle is placed in the OFF position, hydraulic pressure is removed from the retract side of the gear actuators, allowing the gear to settle down and onto the mechanical uplocks, which are essentially hooks that just hold the gear up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a couple reasons why it's beneficial to select OFF. One is that if they remained pressurized, then the gear are essentially hanging in space, at a mechanical stop provided by the actuator. Hydraulic actuators are delicate components, and these weren't designed to hold landing gear for an extended time in the retracted position. Imagine the loads imposed on the actuator in turbulence for example, as the gear are loaded vertically with each bump. Removing hydraulic pressure allows the gear to hang on the mechanical uplocks that were specifically designed to hold them, without putting additional wear on the actuators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other reason is that gear actuators are major users of hydraulic fluid volume, and the actuators and the lines that supply them are a potential for leakage. If they were to remain pressurized for a several hours long flight, that increases the amount of pressurized lines and components that can leak and cause a complete loss of the hydraulic system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that if you look at more recent Boeing airplanes such as the 777, 787, and 747-8, you will not see an OFF position on the gear handle, only DN and UP. The OFF function is done automatically on these models. After you select UP and the gear are all fully retracted, there's a short time delay and the system automatically depressurizes the retract side of the actuators. It removes one After Takeoff checklist item for the pilots to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer some of the questions posed in the comments:&#xA;If you selected OFF while the gear were still in transit in some intermediate position between up and down, they would simply freefall into the down position since you've removed the retraction power.&#xA;If there's a leak in the landing gear actuator or its associated hydraulic lines, it would cause a loss of that hydraulic system, and all other users of that system would be failed. The 737 has two (and a half) hydraulic systems. The half is a standby hydraulic system that's very limited in its function, but I digress.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastEditorUserId="9171" LastEditDate="2015-08-21T05:25:11.900" LastActivityDate="2015-08-21T05:25:11.900" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19181" PostTypeId="2" ParentId="391" CreationDate="2015-08-21T05:54:09.410" Score="2" Body="&lt;p&gt;What you're asking about is essentially a Class E compartment. See this other question/answer for more info: &lt;a href=&quot;https://aviation.stackexchange.com/questions/16331/consideration-of-pets-in-a-cargo-fire-indication/16617#16617&quot;&gt;Is the life of pets considered when dealing with a cargo fire indication?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short answer, yes you can manually depressurize the cabin to try to suppress the fire. But it's a matter of effectiveness. The Class E compartments are used for freighters where the normal &quot;cabin&quot; area is carrying cargo, not passengers. There are three problems with using a Class E method for suppressing a fire in the cabin of a passenger airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the passengers need oxygen. The oxygen masks given to passengers were only designed to give them oxygen in a concentration and duration long enough to keep them alive in the event of a depressurization, and the several minutes it'll take to make an emergency descent to 10,000' where supplemental oxygen isn't needed. The supply of oxygen isn't sufficient for a hours long, or even 30 minute long diversion in the event of a fire/smoke situation. Even if the decision was made to allow the passengers to become hypoxic by not providing them any oxygen because of the fire, that's not possible because the masks will drop automatically once the cabin altitude exceeds 14,000'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, those cheap &quot;dixie cup&quot; masks are not fully sealing. If you look at any oxygen mask that the flight crew uses for example (&lt;a href=&quot;http://aviationoxygen.com/aviation-masks.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://aviationoxygen.com/aviation-masks.html&lt;/a&gt;), you'll see the difference between those and the yellow passenger masks. The flight crew ones are designed to fully seal the mask around the pilot's face so that the pure oxygen being supplied to the pilot doesn't leak into the surrounding environment where there may be a fire. Fire + pure oxygen = bigger fire. So the last thing you would want is the passenger oxygen system to be activated if there's an active fire in the cabin. This, by the way, is the reason why you won't see commercial pilots with beards or extremely long mustaches. Significant amounts of facial hair interfere with the sealing capability of those masks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, and probably biggest reason, is that the Class E method of depressurizing does not extinguish the fire, it simply suppresses it. This has been proven in a couple recent accidents, most notably the UPS6 747-400 that crashed in Dubai (&lt;a href=&quot;https://en.wikipedia.org/wiki/UPS_Airlines_Flight_6&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://en.wikipedia.org/wiki/UPS_Airlines_Flight_6&lt;/a&gt;). Boeing and the industry as a whole, has been re-evaluating the (lack of) effectiveness of depressurization as a fire protection method, not to mention the carriage of lithium ion batteries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most effective way to deal with a fire in the cabin is to attack it directly with fire extinguishers, even if that means cutting into the interior structure and paneling to access the fire. In general, flight crew are provided with the tools and training to do that. The quality and extent of the training provided obviously varies widely depending on the airline, regulatory authority, country, culture, etc.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-08-21T06:01:49.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19182" PostTypeId="1" AcceptedAnswerId="19183" CreationDate="2015-08-21T08:22:37.900" Score="6" ViewCount="1375" Body="&lt;p&gt;I have the following climb performance chart:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/cUrOc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cUrOc.png&quot; alt=&quot;Climb performance chart&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;and I need to evaluate the maximum rate of climb in different flight conditions.&#xA;The problem is, this chart is valid only for 85KIAS. Is there a way to evaluate the maximum rate of climb for other flight speeds, given the RoC and climb gradient @ 85KIAS?&lt;/p&gt;&#xA;&lt;p&gt;edit: The zero-lift drag coefficient and aspect ratio of the aircraft are given. And it is not important if it is an optimum climb or not, I simply need to predict the maximum achievable rate of climb, given flight speed, altitude and aircraft mass.&lt;/p&gt;&#xA;" OwnerUserId="6859" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-22T20:11:34.433" Title="How to determine climb performance for various flight speeds?" Tags="&lt;aircraft-performance&gt;&lt;climb&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19183" PostTypeId="2" ParentId="19182" CreationDate="2015-08-21T08:40:31.707" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/13129/what-are-the-meanings-of-various-reference-lines-and-sections-in-a-take-off-dist/13130#13130&quot;&gt;Aircraft performance charts&lt;/a&gt; all work the same way. Unfortunately, this one only gives the climb speed at 85 knots indicated airspeed (KIAS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To find the climb speed at different speeds needs more knowledge about the airframe. Then you can apply a simple approximation following &lt;a href=&quot;https://aviation.stackexchange.com/questions/420/how-can-i-calculate-maximum-rate-of-climb/12727#12727&quot;&gt;this procedure&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chart does not tell where on the polar the aircraft is. Will it climb better when flying faster or not? This is impossible to tell. Since you have only one speed and one power setting, but a range of masses, the aircraft will not be at its optimum climb setting for most points. We can make an assumption and declare the reference mass of 1700 kg as the point where the cited conditions are at the optimum. But then I would need at least the zero-lift drag and the aspect ratio to make further assumptions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the previous answer we take the climb speed equation $$v_z = \frac{v}{C}\cdot sin\gamma = \frac{v}{C}\cdot\frac{T-D}{m\cdot g}$$&#xA;and set the correction factor C = 1 for now. The resulting error is small at low speeds. Now we need drag and thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First drag: The drag coefficient $c_D$ is approximately&#xA;$$c_D = c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$$&#xA;with the known aspect ratio $AR$ and an assumed Oswald factor $\epsilon$ of 0.85. To arrive from here at the drag we need to multiply this with the dynamic pressure $q = ½\rho\cdot v^2$ and the reference area $S$:&#xA;$$D = ½\rho\cdot v^2\cdot S\cdot c_{D0} + \frac{(1700\cdot g)^2}{½\rho\cdot v^2\cdot S\cdot\pi\cdot AR\cdot\epsilon} = ½\rho\cdot v^2\cdot S\cdot c_{D0} + \frac{(1700\cdot g)^2}{½\rho\cdot v^2\cdot\pi\cdot b^2\cdot\epsilon}$$&#xA;when we substitute $AR = b^2/S$ with $b$ the span of your airplane. As I said before, &lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing/8797?s=3%7C0.1454#8797&quot;&gt;induced drag depends on span, not on aspect ratio&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the thrust. In a propeller aircraft power is constant and thrust is inverse with airspeed. Not indicated, but true airspeed, so we need to be careful. At sea level both are equal, and then thrust is straightforward: $$T = \left(½\rho\cdot v_{ref}^2\cdot S\cdot c_{D0} + \frac{(1700\cdot g)^2}{½\rho\cdot v_{ref}^2\cdot\pi\cdot b^2\cdot\epsilon} + \frac{5.5}{v_{ref}}\cdot1700\cdot g\right)\cdot\frac{v_{ref}}{v}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with $v_{ref}$ = 43.7278 m/s, which is 85 kts in sane units. The first two terms in the bracket look familiar: They are the drag contribution. The third term accounts for the climb speed of 5.5 m/s at the reference point in sea level altitude, so this accounts for the change in potential energy. If you need the thrust at higher altitudes, please correct $v_{ref}$ with the square root of the density ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If those equations look daunting, continue solving for the climb speed:&#xA;$$v_z = \frac{v}{C}\cdot\frac{\left(D + \frac{v_{z_{ref}}}{v_{ref}}\cdot m\cdot g\right)\cdot\frac{v_{ref}}{v} - D}{m\cdot g}$$&#xA;$$v_z = \frac{1}{C}\cdot\left(\frac{D\cdot\left(v_{ref}-v\right)}{m\cdot g} + v_{z_{ref}}\right)$$&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-22T20:11:34.433" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19184" PostTypeId="2" ParentId="17343" CreationDate="2015-08-21T11:56:41.037" Score="3" Body="&lt;p&gt;I am a retired aircraft painter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For electrostatic painting: ensure that the aircraft is grounded; ensure that you are grounded to the gun; use compatible electrostatic paint, this is a must.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My suggestion is, unless you are greatly concern about overspraying, to use a normal system on small aircraft, such as suction fed or gravity fed, as it will do the same job. Application is the same for all systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps&lt;/p&gt;&#xA;" OwnerUserId="9898" LastEditorUserId="1467" LastEditDate="2015-08-21T12:25:16.870" LastActivityDate="2015-08-21T12:25:16.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19187" PostTypeId="1" AcceptedAnswerId="19192" CreationDate="2015-08-21T17:14:53.807" Score="4" ViewCount="987" Body="&lt;p&gt;I was looking at the image of the A 10 and saw that its air frame looks far more stronger than the air frame of the F 15 or the F-16.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eqiMb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eqiMb.jpg&quot; alt=&quot;A 10&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realized that the A 10 is used for undertaking low-level flights for deep interdiction. Apart from the A 10, the French Rafale fighter is also used for low level flights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nenw5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nenw5.jpg&quot; alt=&quot;Rafale&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is it necessary to strengthen the air frame of such aircraft or are they built from scratch with a material that is different from the ones used to design aircraft like F 15 and F 16?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard of designers strengthening high stress areas of air frames with fiberglass,Coffee filters etc. However, increased weight will translate into higher wing loading which means more landing and flying stresses.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sustained low level flights are associated with more structural failures in fighter aircraft. This is why a number of Air Force the world over have mission specific aircraft. Basically what I need to know is whether the airframe  of a fighter aircraft that is generally used for low level flight(A 10, Rafale, Su 34) any different from the airframe of other fighters like F 15, F 16 or Typhoon? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be sure, I got the answer from the posts below, but just wanted to clarify as this question is on hold.   &lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="9142" LastEditDate="2015-08-22T09:08:58.550" LastActivityDate="2015-08-25T21:20:15.740" Title="Is it necessary to strengthen the airframe of an aircraft that is used for sustained low level flight?" Tags="&lt;aircraft-design&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19188" PostTypeId="2" ParentId="19187" CreationDate="2015-08-21T18:26:52.177" Score="3" Body="&lt;p&gt;&quot;Strength&quot; is not really something you can deduce from simply looking at an aircraft. That being said, in a manner of speaking the A-10 may be &quot;Stronger&quot; than its &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Overview&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt; counterpart but they fill different roles so you are comparing apples to oranges. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-10 does have &lt;a href=&quot;http://www.airforce-technology.com/projects/a-10/&quot; rel=&quot;nofollow noreferrer&quot;&gt;titanium armor&lt;/a&gt; plating around the cockpit which I don't think the F-16 has&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The single-seat [...A-10] cockpit is protected by all-round armor, with a titanium 'bathtub' structure.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are also of course stores that must be taken in context like &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A-10's durability was shown on 7 April 2003 when Captain Kim Campbell, while flying over Baghdad during the 2003 invasion of Iraq, suffered extensive flak damage. Iraqi fire damaged an engine and crippled the hydraulic system, requiring the aircraft's stabilizer and flight controls to be operated via the 'manual reversion mode'. Despite this damage, Campbell flew the aircraft for nearly an hour and landed safely.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which of course can be turned into people thinking the A-10 is &quot;Stronger&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there are pics like this that make it look like the plane can take quite a beating (which apparently it can) &#xA;&lt;a href=&quot;https://i.stack.imgur.com/X5cTv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X5cTv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets look at some airframe specs  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.simhq.com/_air/air_052a.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-10 load limits&lt;/a&gt; are &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The maximum G-loads for the A-10 with a weight around 30,000 pound is +7.33/-3.0 G symmetrical and +5.80/-1 G asymmetric.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt; racks in at &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;F-16 was the first fighter aircraft purpose-built to pull 9-g maneuvers and can reach a maximum speed of over Mach 2&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;so in that regard you may be able to argue that the F-16 is stronger due to its maximum load limit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth the exterior of a plane sheds little light on the airframe inside. Here is an example, this nice little single seat Mooney Looks pretty strong, but its made of plywood and fabric mainly.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iDqVt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iDqVt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-08-21T18:26:52.177" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19190" PostTypeId="1" CreationDate="2015-08-21T19:40:27.323" Score="1" ViewCount="883" Body="&lt;p&gt;More specifically: in Canada what are reasons and protocols of keeping a logbook?&lt;/p&gt;&#xA;" OwnerUserId="870" LastActivityDate="2015-08-21T21:08:42.690" Title="What exactly is the purpose of a pilot keeping a logbook?" Tags="&lt;logging&gt;&lt;canada&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19191" PostTypeId="1" AcceptedAnswerId="19575" CreationDate="2015-08-21T20:03:40.950" Score="9" ViewCount="1371" Body="&lt;p&gt;Some other questions about HUDs and how they work got me thinking. Military aircraft have had reflector sights since before WWII, and full HUDs since the mid-70s. The very same display layout, sans targeting recticles, is fairly familiar to pilots of glass-cockpit aircraft, the primary difference being the representation of the artificial horizon (which, because the display is &lt;em&gt;not&lt;/em&gt; a HUD and so not transparent, uses the blue/brown background from the analog instrument). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;True HUD systems are starting to make their way into commercial airliners, and the technology is even seen in various cars (primarily luxury brands) as a situational awareness tool. So the question is, what types of reflector-sight flight display systems are available for light singles? I would assume a glass cockpit is a prerequisite to generate the digital display, but given that concession, it seems fairly straightforward to have a monochrome version of the PFD projected onto a glass plate instead of or in addition to the display on the LCD monitor. Has anyone marketed this? Are there disadvantages of having a HUD in a GA aircraft that I'm not thinking about? This sounds like a natural next step now that even entry-level LSAs are foregoing the traditional analog 6-pack for glass displays.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="69" LastEditDate="2015-09-01T21:41:47.677" LastActivityDate="2015-09-02T13:05:30.913" Title="Are HUD systems available for light GA aircraft?" Tags="&lt;general-aviation&gt;&lt;glass-cockpit&gt;&lt;hud&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19192" PostTypeId="2" ParentId="19187" CreationDate="2015-08-21T20:18:03.953" Score="9" Body="&lt;p&gt;Since the question you're ostensibly asking is &quot;Do you need to strengthen the airframes of aircraft used for sustained low-level flight&quot; let's leave aside the military aircraft in your question and just look at &quot;sustained low-level flight&quot; in general.&lt;br&gt;&#xA;But first let's bear in mind two concepts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first concept is that all aircraft (indeed, all structures) have a finite fatigue life: through normal use, vibration, operating stresses from takeoffs/landings/maneuvers, etc. an aircraft accumulates a certain amount of &lt;em&gt;fatigue&lt;/em&gt;, and at some point that fatigue will lead to failures (bending or cracking) in the aircraft's structures.&lt;br&gt;&#xA;Aircraft are engineered to withstand a certain amount of fatigue (the &quot;fatigue life&quot; of the airframe) based on a number of factors, and when the fatigue life limit is reached the airframe is either retired (scrapped) or rebuilt/reinforced to extend the fatigue life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second concept is something in fluid dynamics called a &lt;em&gt;boundary layer&lt;/em&gt; - the region of a fluid in contact with (and most influenced by) some surface.&lt;br&gt;&#xA;For purposes of flight we can consider air (the atmosphere) to be a fluid in contact with the Earth's surface. This means down close to the Earth's surface there's a boundary layer with associated meteorological phenomena.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.nws.noaa.gov/om/aviation/front/14feb-front.pdf&quot;&gt;The first article in this NOAA piece talks about some of them&lt;/a&gt;, but for purposes of this discussion let's just reduce it to &quot;It's really bumpy and gusty in the boundary layer. Once you climb above the boundary layer the air is smoother.&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Bearing these two concepts in mind, an aircraft that spends most of its time operating down load (near the surface of the Earth) is also spending most of its time &lt;em&gt;inside the boundary layer&lt;/em&gt;, where it gets bounced around and shaken up more by the turbulence in the boundary layer, and thus accumulates fatigue at an accelerated rate.&lt;br&gt;&#xA;Because of this aircraft that spend a lot of time in the boundary layer are usually &quot;overbuilt&quot; to handle a greater degree of fatigue/stress, or have reduced service/fatigue life limits to ensure the aircraft is inspected and repaired/retired before fatigue can lead to a failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accelerated fatigue from spending a lot of time in the boundary layer can also be dealt with by inspections rather than engineering changes. &lt;a href=&quot;https://bsd-box.net/~mikeg/N8031W/SB_SL/SB%20886.pdf&quot;&gt;Piper Service Bulletin 886&lt;/a&gt; highlights a particularly dramatic case:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On March 30, 1987, a PA-28 engaged in pipeline patrol operations suffered an in-flight wing separation resulting in a fatal accident. Investigation revealed the wing failure was due to propagation of a fatigue crack, which originated in the wing lower main spar cap.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Piper then goes on to describe &quot;Normal&quot; and &quot;Severe&quot; usage of the PA-28 family of aircraft, broadly speaking &lt;strong&gt;Normal&lt;/strong&gt; is flying &quot;normally&quot; (Take off, climb to an altitude generally above the boundary layer, fly to your destination, and land), while &lt;strong&gt;Severe&lt;/strong&gt; usage involves spending a lot of time in the boundary layer (&quot;below 1000 feet AGL&quot;). They then recommend inspection intervals based on the type of usage the aircraft is seeing (around 60,000 hours for &quot;normal&quot; usage, and roughly half that for &quot;severe&quot; usage due to the accelerated fatigue accumulation).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;TL ; DR&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Most aircraft that spend most of their time at low altitudes (close to the ground) are &quot;overbuilt&quot; structurally because there is more turbulence down low, so they accumulate fatigue at an accelerated rate.&lt;br&gt;&#xA;Plenty of &quot;normal&quot; aircraft also spend a lot of their life at low altitudes, and this is usually handled by inspecting them for signs of fatigue damage more frequently than their higher-altitude counterparts.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-08-21T20:32:39.643" LastActivityDate="2015-08-21T20:32:39.643" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19193" PostTypeId="2" ParentId="19187" CreationDate="2015-08-21T20:46:24.823" Score="3" Body="&lt;p&gt;First, I disagree that the A-10 airframe &quot;...looks stronger than...&quot; that of the F-16.  But that's a personal opinion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to emphasize the concept mentioned by others:  Each of these aircraft is designed and built to execute a role on (above?) the modern battlefield.  Almost by definition each is strong enough to fulfill that role.  Mistakes have been made (see the re-design and reinforcement of the C-5 cargo plane's wings as one example) but that is what happens when the designers push the envelope to produce a state of the art aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer to your question is &quot;yes, the planes are purpose built for their role.&quot;  Also true, however, is that the engineers are always learning from the successes and failures of engineers on other planes.  And incorporate the good ideas and good new applications of technology on the next plane to be designed and built.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-08-21T20:46:24.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19194" PostTypeId="1" AcceptedAnswerId="19196" CreationDate="2015-08-21T21:07:22.903" Score="2" ViewCount="8482" Body="&lt;p&gt;After finding out how well the variable swept wing design served the F-14, why hasn't it been used more often (outside of a select few)? Almost all of the fighters after the cold-war era haven't used variable swept wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: is there any significance to the way the F22/F35 wings are shaped almost like triangles?&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/4/46/Lockheed_Martin_F-22A_Raptor_JSOH.jpg&quot; alt=&quot;f22&quot;&gt;&#xA;&lt;img src=&quot;https://a57.foxnews.com/global.fncstatic.com/static/876/493/F35.jpg?ve=1&amp;amp;tl=1&quot; alt=&quot;f35&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9907" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.493" LastActivityDate="2017-07-28T04:38:51.133" Title="Why aren't variable swept wings being used in newer military aircraft?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-08-21T22:39:12.030" ContentLicense="CC BY-SA 3.0" />
  <row Id="19195" PostTypeId="2" ParentId="19190" CreationDate="2015-08-21T21:08:42.690" Score="2" Body="&lt;p&gt;Almost everything in flying is measured in hours, including your experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To start with, in most places you need to have trained a certain number of hours before taking your flying skills test, regardless of how good you are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then it continues, want to do an instrument rating, you need x hours. Want to be an instructor, you need y hours. Want to be a Captain on a 747, well you'll need z hours as First Officer first and to be First Officer, you'll need....guess what!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, many countries place restrictions on what you can and can't do based on your recent experience. For example, in the UK, to take passengers you must have performed three landings on type within 90 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then it carries on outside of legislation, too - if you want to rent a plane most places will place some sort of hour requirement, whether it be your total hours or hours on type etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And so it follows that you need somewhere to log this. As a pilot your log book is sacrosanct - its a legal document forming a factual record of your flying experience.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-08-21T21:08:42.690" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19196" PostTypeId="2" ParentId="19194" CreationDate="2015-08-21T21:50:09.607" Score="6" Body="&lt;p&gt;The main advantage of variable sweep wings is that they reduce drag over a wide range of Mach numbers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the variable sweep wings are not being used in present day aircraft for a variety of reasons.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The variable sweep wings are heavy and mechanically complex, affecting performance and maintenance.&lt;/li&gt;&#xA;&lt;li&gt;The swing mechanism takes up too much space inside the wing that could be used for fuel.&lt;/li&gt;&#xA;&lt;li&gt;It is difficult to position hard-points in the swinging part of the wing, affecting payload.&lt;/li&gt;&#xA;&lt;li&gt;Advances in aerodynamics and better engines mean that the drag reduction using varying the wing sweep is not so critical anymore.&lt;/li&gt;&#xA;&lt;li&gt;Also, the newer combat aircraft are not trying to outdo each other in speed, trying to gain the edge using better situational awareness, stealth etc.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;However, the most important reason for variable sweep wings falling out of favor is that they are nearly impossible to be made stealthy. One way to make the aircraft stealthy is to reflect the Radar energy away from the source. In order to achieve this, the wings of stealth aircraft are designed in a specific way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if the aircraft have a variable sweep wing, this condition is all but impossible to achieve. If stealth is still required, it has to be through more Radar absorbent materials, which further increases weight and maintenance requirements. The last variable sweep aircraft, &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;noreferrer&quot;&gt;B-1B&lt;/a&gt;, for example is designed to be a low level penetrator, unlike B2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of these reasons, the variable sweep wings have fallen out of favor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the second question, the wings of F22/F35 has basically a &lt;a href=&quot;https://en.wikipedia.org/wiki/Trapezoidal_wing&quot; rel=&quot;noreferrer&quot;&gt;trapezoidal wing&lt;/a&gt; configuration, which gives a high performance at high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the main reason for using this type of wings is the excellent stealth characteristics they provide compared with other type of wings. One disadvantage of this type of wings is that their low speed performance is not up to the mark, but this has mostly been overcome by the use of improved control surfaces (like flaps, slats etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, USN considered a variable sweep F22 for carrier operations, but the project was ultimately dropped.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2017-07-28T04:38:51.133" LastActivityDate="2017-07-28T04:38:51.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19197" PostTypeId="1" AcceptedAnswerId="19199" CreationDate="2015-08-21T21:54:51.403" Score="-2" ViewCount="5631" Body="&lt;p&gt;I know the q400 is one of few airliners that has a turboprop engines. I know that some military airplanes use turboprop engines so why don't many airliners use them?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9875" LastEditDate="2015-08-22T02:51:46.933" LastActivityDate="2015-08-22T02:51:46.933" Title="Why don't airliners have turboprop engines instead of jet engines?" Tags="&lt;airliner&gt;&lt;turboprop&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-08-22T13:29:34.580" ContentLicense="CC BY-SA 3.0" />
  <row Id="19198" PostTypeId="1" AcceptedAnswerId="19200" CreationDate="2015-08-21T22:14:58.463" Score="6" ViewCount="1930" Body="&lt;p&gt;If you know the 787 wing flex is much greater than the 747-8's wing why can't the 747-8 have a greater wing flex&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="19" LastEditDate="2017-08-14T08:44:17.447" LastActivityDate="2017-08-14T08:44:17.447" Title="Why does the boeing 747-8 have less wing flex than the 787?" Tags="&lt;boeing-747&gt;&lt;boeing-787&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19199" PostTypeId="2" ParentId="19197" CreationDate="2015-08-21T22:20:51.453" Score="6" Body="&lt;p&gt;Turboprop engines are used in ATR aircraft too. The main reason the airlines are not using turboprop engines are,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;They are not as efficient as jet engines for high altitude long distance flights. This is why all the turboprop aircraft are used of short haul flights.&lt;/li&gt;&#xA;&lt;li&gt;Their efficiency decreases as the speed increases above Mach 0.6~0.7.In comparison, Boeing 747-8 cruises at around Mach 0.85.(Their efficient (cruise) speed is less compared to jet aircraft(~700-750 kmph versus ~880-840 kmph). This adds quite a bit of travel time to long haul flights.&lt;/li&gt;&#xA;&lt;li&gt;The cabin (and outside) is significantly quieter in case of turbofan engines when compared turboprop engines. This is an important issue in case of civil aircraft where the noise (and vibrations) affect passenger comfort. &lt;/li&gt;&#xA;&lt;li&gt;The turbofan engines produce a lot more thrust compared to turboprop engines, for a given size(the turboprop engine output is measured in shaft power though). This makes them unsuitable for large aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The huge propellers in the large turboprop aircraft require long landing gears which increase the weight and complicate the maintenance.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The largest (and fastest) turboprop powered civil aircraft, flew slower and lower than jet aircraft from comparable era. It wasn't known for its comfort either.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3825" LastEditDate="2015-08-21T23:10:47.230" LastActivityDate="2015-08-21T23:10:47.230" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19200" PostTypeId="2" ParentId="19198" CreationDate="2015-08-21T23:12:09.040" Score="14" Body="&lt;p&gt;The reason is twofold: The materials used and the high aspect ratio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747-8 primarily uses advance aluminum alloys, while the 787 uses carbon composites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The carbon composites flex more compared to the aluminum alloys. This can be achieved because the carbon fibers are anisotropic and their properties can be &lt;em&gt;tailored&lt;/em&gt; in each direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The yield strain of the aluminum alloys used in aerospace is ~1%, while that of the &lt;a href=&quot;http://machinedesign.com/materials/basics-aerospace-materials-aluminum-and-composites&quot; rel=&quot;nofollow noreferrer&quot;&gt;carbon composites&lt;/a&gt; is about 50% higher, ~1.5%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These material characteristics mean that the carbon spar can flex more compared to the aluminum one. This effect is magnified by the high aspect ratio of the Boeing 787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aspect ratio of the 787 is about &lt;a href=&quot;http://galexander.org/dreamliner.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;11&lt;/a&gt; while that of the 747-8 is about &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;8.5&lt;/a&gt;. This means that the wings are more slender and flex more for the same load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787 wings are able to take this flexing in part because of the excellent fatigue properties of the Carbon composites used. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/838/what-are-the-effects-of-the-boeing-787s-very-flexible-wings&quot;&gt;this question&lt;/a&gt; for a very good discussion on the causes and effects of wing flexing in 787.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-08-24T15:31:51.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19201" PostTypeId="2" ParentId="19187" CreationDate="2015-08-21T23:52:52.927" Score="8" Body="&lt;p&gt;The A-10 looks the way it does because it is a plane designed not just to fly low, but to fly low, slow, and fully-loaded over terrain containing a lot of people who want to shoot that aircraft down, because they know if they don't do it quickly, they're dead. Every aspect of the A-10's design is intended to facilitate the aircraft's use in such an environment and give it the highest chance of coming back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-10 is actually not intended for deep interdiction; that mission is more often given to the F-15E, F-16, or the B-1B, depending on range, payload requirements and availability. The A-10, especially the newer C variant which has an onboard laser designator for smart bombs, can go bunker-busting behind enemy lines if it has to, but its maximum speed and service ceiling are too low for real penetration work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-10 was built for a single purpose: close air support (or CAS). It was designed to take a lot of weapons into the sky over the front lines, supplementing and supporting friendly infantry and armor by taking out enemy armor and artillery. Most of those enemies would be able to shoot back, using anything from AK-47s and shoulder-fired Stingers to MPAT shells and mobile AAA/SAM launchers like the SA-13 or ZSU-23. To that end, it was built for a high payload capacity, good close-quarters maneuverability, long loiter times, extreme durability, and an on-board cannon capable of engaging armored targets (these last three elements being totally absent from Vietnam-era F-105 and F-4 ground attack aircraft, while Marine Hueys and Cobras had insufficient armor-piercing capability to engage the NVA's Soviet-supplied tanks). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These elements also make the aircraft good for other shorter-range ground missions, such as BAI (Battlefield Air Interdiction; destroying ground forces behind the front lines on their way to make trouble) and SEAD (Suppression of Enemy Air Defenses; this task is more often given to F-16s which can carry the HARM anti-radar missile, but if the A-10 can see a SAM launcher, it can kill it). While not designed for the task, the A-10 is more than a match for enemy helicopters, typically carrying a pair of Sidewinders under one wing (a 30MM burst from the GAU-8 will also do the trick).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was also built on a budget; with the F-14 and F-15 air superiority programs costing over \$30 million a plane, getting the additional money for a dedicated small ground attack plane through Congress was difficult, so the winner of the AX program had to have a unit cost less than \$1 million. That meant that researching radically new wing planforms and fuselage design concepts just wasn't in the budget; both the A-10 and the YA-9 that lost to it were built very simply using proven design elements hearkening back to the first generation of jet fighters and even to WWII-era light bombers. The A-10A variant originally cost just \$450,000; modern A-10Cs, with glass cockpits and more advanced targeting systems for smart weapons, are still &lt;em&gt;only&lt;/em&gt; \$11 million in more recent dollar figures. Compared to the F-15E's \$31 million unit cost, and the A-10's replacement the F-35 costing \$98 million each, the A-10C is still an unbelievable bargain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result of all these design requirements, the A-10 has straight wings with a much thicker cross-section, generating more lift at lower speeds and a smaller target area than the F-15's tennis-court-sized planform. Those thick wings are also designed for 6g maneuvering with up to 16,000 pounds of ordnance hanging from them. An additional reason for so much lift and wing volume is that the aircraft is designed to fly with half a wing missing (in addition to an engine and half its tail), and has dual redundant hydraulic loops to all control surfaces plus a set of good old-fashioned cable controls should the main hydraulic or electrical system fail (the core components for both of these being housed in the &quot;titanium tub&quot; that protects the pilot and core avionics).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design considerations for the F-15 were different. The requirements for the Eagle favored high speed and maneuverability (the MiG-25 and its purported capabilities had really scared the USAF top brass; it turned out to be fast, but really heavy, and so it wasn't the dogfighter NATO feared it would be when they saw its wings in recon pictures), a high ceiling (it's called the Eagle for a reason) and &quot;not a pound for air to ground&quot;, focusing on BVR aerial engagements using Sidewinders and Sparrows (now AMRAAMs) with the additional ability to mix it up at visual range with Sidewinders and guns. In short, the USAF wanted the best pure air-to-air fighter money could buy, and for its day they spared no expense; the F-15C has a unit cost around \$30 million, figured primarily in late 1970s dollars (the equivalent of $133 million a plane today, not that much less than the Raptor program).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16, and its runner-up in the LWF competition the YF-17 (which the Navy would develop into the F/A-18), had a slightly different purpose; to be the best dogfighter that $16 million would buy, that could also drop bombs. The idea was to supplement the ridiculously expensive F-15 with something the USAF could afford to lose a few of in establishing air superiority and suppressing ground-based air defenses. The program emphasized a small, nimble, affordable fighter capable of attacking any target the USAF would be assigned, air or ground.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="4474" LastEditDate="2015-08-25T21:20:15.740" LastActivityDate="2015-08-25T21:20:15.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19202" PostTypeId="1" CreationDate="2015-08-22T01:38:16.257" Score="7" ViewCount="7289" Body="&lt;p&gt;The Airbus A380 has a wing with aspect ratio between 7 and 8.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot;&gt;Reference here&lt;/a&gt;.  The lift to drag ratio is somewhere between 19 and 20, which is comparable to aircraft with higher aspect ratios and superior to aircraft with similar aspect ratios.  A reference to the lift/drag number is &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/333428/&quot;&gt;here&lt;/a&gt;.  How can the A380 achieve this?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-08-24T13:40:00.227" Title="How can the Airbus A380 have such a high lift/drag with a relatively low aspect ratio wing?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19203" PostTypeId="1" AcceptedAnswerId="19205" CreationDate="2015-08-22T02:57:30.910" Score="0" ViewCount="529" Body="&lt;p&gt;Wings are pretty smooth these days and air travels over the wing easier, so what is the smoothest material&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="13197" LastEditDate="2016-04-25T10:27:49.117" LastActivityDate="2016-04-25T10:27:49.117" Title="What material is the smoothest for air to travel over the wing?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ClosedDate="2015-08-22T13:28:38.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="19204" PostTypeId="1" CreationDate="2015-08-22T04:04:32.307" Score="3" ViewCount="169" Body="&lt;p&gt;Is there an equivalent? Googling I didn't learn much.&lt;/p&gt;&#xA;" OwnerUserId="870" LastEditorUserId="870" LastEditDate="2015-08-22T08:39:26.797" LastActivityDate="2015-08-23T13:40:44.283" Title="What's the Canadian equivalent of a Biennial Flight Review?" Tags="&lt;canada&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19205" PostTypeId="2" ParentId="19203" CreationDate="2015-08-22T04:41:18.343" Score="5" Body="&lt;p&gt;Well first let's dispel the rumor that wings are &quot;pretty smooth&quot; - ideally (in the dreams of aircraft designers and the mathematical perfection of fluid dynamics modeling) they would be, and they certainly are from a distance, but when you get up close and personal most aircraft wings are ugly, bumpy things (as you'll see below). Modern composite wings are a notable exception to this general rule, but there are a few other exceptions in the history of aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;material&lt;/em&gt; is, for the most part, not relevant: We usually paint aircraft, so the smoothness of the underlying material contributes less to the surface than the paint preparation, clear coat, and wax.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does matter are the &lt;em&gt;construction techniques&lt;/em&gt; used. A few examples (in rough order of decreasing smoothness):  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A modern composite wing can have an almost completely smooth surface (with no rivets or seams in the airflow) - for example a 787 wing, or this SR-20 wing:&lt;br&gt;&#xA;&lt;a href=&quot;http://philip.greenspun.com/flying/cirrus-sr20&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PjMTd.jpg&quot; alt=&quot;Cirrus SR-20 Composite Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some aluminum designs use &quot;bonded construction&quot; (glue) with fewer disruptions of the wing surface. One example are the Grumman AA-1 and AA-5 series aircraft, which has a smooth wing except for the fuel caps and contoured seam lines:&lt;br&gt;&#xA;&lt;a href=&quot;http://www.grumman581.sh-cs.net/main/aviation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ztijE.jpg&quot; alt=&quot;Grumman Tiger Bonded Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Conventional aluminum wings can be assembled with flush rivets, which once primed and painted give a very smooth surface with only slight irregularities around each rivet:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WBufM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WBufM.jpg&quot; alt=&quot;RV-14 flush-riveted wing&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Please ignore the blue protective film, and open rivet holes. This is from &lt;a href=&quot;http://rv-14a.blogspot.com/2013/07/wings-fuel-tank-stiffeners-riveting.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;an RV-14 under construction&lt;/a&gt; &amp;amp; was the best photo I could find.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fabric wings - one of the oldest wing coverings - are actually pretty smooth. They have &quot;rib stitching&quot; to attach them to the substructure, and are stretched taught over the frame (using heat &amp;amp; dope to shrink the fabric), but the overall result is a very smooth surface between the ribs, with some irregularity over them from the stitches:&lt;br&gt;&#xA;&lt;a href=&quot;http://wingandawhim.blogspot.com/2010/09/left-wing-finished.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lz9OE.jpg&quot; alt=&quot;Fabric Wing with stitching&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Typical aluminum aircraft wing is attached with typical rivets - the head of which protrudes into the airflow slightly. You can see some rivet (and screw) shadows in this image:&lt;br&gt;&#xA;&lt;a href=&quot;https://www.flickr.com/photos/jayjerry/3956556078/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TJhXa.jpg&quot; alt=&quot;Conventional aluminum wing rivets&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that I've only considered the &lt;strong&gt;&lt;em&gt;TOP surface&lt;/em&gt;&lt;/strong&gt; of the wing (where airflow and smoothness is most critical). The underside of a wing usually has many other things sticking out into the airflow (fuel tank vents, access/inspection panels, hinges &amp;amp; tracks for control surfaces, etc.) which are a much greater disturbance to the airflow than whatever fasteners are attaching the skin to the rest of the structure of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="4197" LastEditDate="2015-08-22T08:26:04.563" LastActivityDate="2015-08-22T08:26:04.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19206" PostTypeId="2" ParentId="19202" CreationDate="2015-08-22T07:42:55.113" Score="8" Body="&lt;p&gt;The aspect ratio of the aircraft is usually kept as high as possible to reduce the induced drag. However, it forms only one part of the total drag acting one the body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The L/D ratio can be improved by either increasing the (coefficient of) lift or decreasing the (coefficient of) drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While no data is available in open sources, it is likely that the wing airfoil was designed for high lift in cruise conditions. Also, the wing has a number of high-lift-devices to increase lift like the flaps, droop nose etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in order to improve the L/D ratio during initial takeoff and climb, the A380 incorporated a &lt;a href=&quot;https://en.wikipedia.org/wiki/Droop_%28aeronautics%29&quot; rel=&quot;noreferrer&quot;&gt;droop nose device&lt;/a&gt; in the inboard leading edge. This improved the lift by around 5%. The figure below shows A380 deploying droops during landing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jsbjb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jsbjb.jpg&quot; alt=&quot;A380 with droops deployed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A380_F-WWEA_LEGT.jpg#/media/File:A380_F-WWEA_LEGT.jpg&quot; rel=&quot;noreferrer&quot;&gt;A380 F-WWEA LEGT&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Keta&quot; rel=&quot;noreferrer&quot; title=&quot;User:Keta&quot;&gt;User:Keta&lt;/a&gt; - Own work. Licensed under CC BY-SA 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic drag on a body is a combination of a large number of components like&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Induced Drag&lt;/li&gt;&#xA;&lt;li&gt;Parasitic Drag&lt;/li&gt;&#xA;&lt;li&gt;Wave Drag.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The (lift) induced drag is lesser for aircrafts with higher aspect ratio. In designing the A380 however, the &lt;a href=&quot;http://leehamnews.com/2014/02/03/updating-the-a380-the-prospect-of-a-neo-version-and-whats-involved/&quot; rel=&quot;noreferrer&quot;&gt;limitations of airport operations&lt;/a&gt; meant that the wingspan was limited. This resulted in a rather low aspect ratio of 7.8. However, the same effect(of higher aspect ratio) can be achieved using wingtip devices such as winglets. A380 uses wingtip fences to reduce induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sJ2zd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sJ2zd.jpg&quot; alt=&quot;A380 wingtip fence&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:British_Airways_Airbus_A380-841_F-WWSK_PAS_2013_10_Wingtip_device.jpg#/media/File:British_Airways_Airbus_A380-841_F-WWSK_PAS_2013_10_Wingtip_device.jpg&quot; rel=&quot;noreferrer&quot;&gt;British Airways Airbus A380-841 F-WWSK PAS 2013 10 Wingtip device&lt;/a&gt;&quot; by Julian Herzog. Licensed under CC BY 4.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the speed increases, the induced drag reduces and the parasitic drag (of which the form drag is a component) comes to dominate the drag produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K6Je4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K6Je4.jpg&quot; alt=&quot;Drag Curve&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Drag_Curve_2.jpg#/media/File:Drag_Curve_2.jpg&quot; rel=&quot;noreferrer&quot;&gt;Drag Curve 2&lt;/a&gt;&quot; by Original uploader was GRAHAMUK at en.wikipedia - Transferred from en.wikipedia; transferred to Commons by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Sfan00_IMG&quot; rel=&quot;noreferrer&quot; title=&quot;User:Sfan00 IMG&quot;&gt;User:Sfan00_IMG&lt;/a&gt; using CommonsHelper.. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major part of the parasitic drag is the form drag, caused by the movement of aircraft through the air. The A380 design reduces this by reducing the control surface areas through the use of Fly by wire system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is also achieved by reducing the drag caused refining the aerodynamics of the aircraft, such as by using improved flap track fairings and increased size of the belly fairing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QRcLn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QRcLn.jpg&quot; alt=&quot;A380 flap track fairings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lHFvc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lHFvc.jpg&quot; alt=&quot;A380 belly fairing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Singapore_Airlines_A380_9V-SKH.jpg#/media/File:Singapore_Airlines_A380_9V-SKH.jpg&quot; rel=&quot;noreferrer&quot;&gt;Singapore Airlines A380 9V-SKH&lt;/a&gt;&quot; by Simon_sees - Singapore Airlines A380 9V-SKH. Licensed under CC BY 2.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The overall aircraft configuration and not just the individual components were analyzed using CFD, which led to further optimization of the aerodynamics design and reduction of drag by changing the spanwise distribution of camber and twist from root to tip (around 2%).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airfoil used was most probably optimized for reducing wave (transonic) drag, though no data is available in open literature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though all these improvements were only marginal individually, put together, they have a significant impact on the overall L/D ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One more thing to note is that though the L/D ratio might appear high, the value is actually comparable (and even less than) the aircrafts that enter service after A380. So in a way, there is nothing surprising about the L/D ratio of A380 except that it illustrates the steady progress being made in civil airliner aerodynamic design.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-22T07:42:55.113" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19207" PostTypeId="2" ParentId="19173" CreationDate="2015-08-22T11:16:14.980" Score="4" Body="&lt;p&gt;Rudder itself was used before the Wright. It was just the idea of a rudder on a boat. &lt;a href=&quot;https://en.wikipedia.org/wiki/Otto_Lilienthal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Otto Lilienthal&lt;/a&gt; flew a glider which had a tail with a modern look in 1894:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1cRXJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1cRXJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://fr.wikipedia.org/wiki/Otto_Lilienthal#/media/Fichier:Planeur_de_Lilienthal_musee_du_Bourget_P1010381.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually the whole airplane has a modern look, like the cambered wing, Lilienthal was an aerodynamicist, he invented the &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_curve_(aerodynamics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;polar curve&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The rudder is not meant to control the aircraft direction --this is done by rolling the wing,-- but to counteract the adverse yaw which develops when the wing is rolled (more drag on the upper half of the wing). This effect can be obtained even with a fixed rudder (the turn will not be &lt;em&gt;coordinated&lt;/em&gt;, but this tends to prevent a spiral dive).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LER4h.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LER4h.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Adverse yaw in a roll (&lt;a href=&quot;http://cargocollective.com/ford/ICON-Aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;, more in &lt;a href=&quot;https://aviation.stackexchange.com/a/24102/3201&quot;&gt;this answer&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the size of the rudder is proportional to this force, which is smaller on small wings.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-09-28T08:41:28.110" LastActivityDate="2019-09-28T08:41:28.110" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="19208" PostTypeId="1" AcceptedAnswerId="19211" CreationDate="2015-08-22T15:39:17.943" Score="3" ViewCount="6328" Body="&lt;p&gt;I ask this because the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747#747-200&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-236&lt;/a&gt; had the engines close together while the 747's have them spread apart. Does it have anything to do with the amount of thrust of the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at how spread apart the engines are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vjnME.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vjnME.jpg&quot; alt=&quot;747 in hangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now look at how close together those engines are on the Boeing 747-236:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KS7FZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KS7FZ.jpg&quot; alt=&quot;747-268B used as movie prop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-08-23T00:22:03.733" LastActivityDate="2015-08-23T22:14:45.890" Title="Why are the Boeing 747-8 engines on the wings spread apart?" Tags="&lt;boeing-747&gt;&lt;engine-placement&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ClosedDate="2015-08-22T23:47:03.090" ContentLicense="CC BY-SA 3.0" />
  <row Id="19209" PostTypeId="2" ParentId="19208" CreationDate="2015-08-22T15:49:19.720" Score="21" Body="&lt;p&gt;That picture of the 747-200 you have with the engines in a pod together like a B-52 is a movie prop. &lt;a href=&quot;http://www.airliners.net/photo/Boeing-747-236B/1070481/&quot;&gt;http://www.airliners.net/photo/Boeing-747-236B/1070481/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All real 747s from the -100 through the -8 have their engines positioned like the first picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT - Federico's response reminded me of another aspect of the engine position, and to answer your original question of why they're spread apart. Spacing between the 747s engines is important due to the need to maintain sufficiently clean airflow into the inlet. If the engines are too close together, they're essentially competing for the same amount of air, and at high power settings, the interaction between the two fans will disrupt their operation, potentially causing engine stall/surge. Additionally, the 747 uses thrust reversers, and the spacing between the engines helps ensure that the reverse flow from each engine doesn't impact an adjacent engine, for the same inlet distortion reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume, though I don't know the details of this, that the B-52 can have them that close together because they've shown that the inlet geometry, airflow required by each engine, whatever other magic of fluid dynamics that I know nothing about, prevents the engines from distorting each other's airflow enough to cause an issue. The 747 engines require a lot more air, and generate a lot more thrust, and are potentially more sensitive to inlet disruption than the engines on the B-52. This last paragraph is mostly a guess on my part as I'm not an aerodynamicist, but it's inferred from issues we've had to deal with on the 747 and other related airplanes.&lt;/p&gt;&#xA;" OwnerUserId="9171" LastEditorUserId="9171" LastEditDate="2015-08-22T16:08:04.690" LastActivityDate="2015-08-22T16:08:04.690" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19210" PostTypeId="2" ParentId="19208" CreationDate="2015-08-22T15:54:13.873" Score="9" Body="&lt;p&gt;In addition to what &lt;a href=&quot;https://aviation.stackexchange.com/a/19209/1467&quot;&gt;Stickhog's answer&lt;/a&gt; says, the fact that all 747s (and A380s) have their engines spread apart has to do with the &quot;single point of failure&quot; concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider for a moment &lt;a href=&quot;https://i.stack.imgur.com/KS7FZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;the picture of the movie prop&lt;/a&gt; you posted, if one of the pylons suffer any kind of mechanical failure, you lose 2 engines. The same with one of the engines suffering explosive failure or uncontained fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having the engines separated from each other reduces the risk that a failure that renders one engine inoperative will affect also another engine.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-08-22T15:54:13.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19211" PostTypeId="2" ParentId="19208" CreationDate="2015-08-22T18:17:30.327" Score="6" Body="&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It's the vastly different flow conditions from static to cruise which demand a separate placing of high-bypass-ratio jet engines. They would produce less thrust and more drag when paired.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why were there paired engines at all?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The early jets had their engines mounted directly beneath or in the wing, and comparisons between separately mounted and twinned engines showed a slight advantage for the latter due to lower wetted surface area and less impact on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arado built two four-engined prototypes of their &lt;a href=&quot;http://en.wikipedia.org/wiki/Arado_Ar_234&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ar-234&lt;/a&gt; jet, one with separate engines (V6, see directly below) and one with paired engines (V8, further down).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/7l3im.jpg&quot; alt=&quot;Arado 234 V6&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/y9yop.jpg&quot; alt=&quot;Arado 234 V8&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This twinned arrangement works well with turbojets and low-bypass-ratio turbofans. The Boeing &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-47_Stratojet&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-47&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-52&lt;/a&gt; bombers, and among airliners the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-62&quot; rel=&quot;nofollow noreferrer&quot;&gt;Illyushin 62&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_VC10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vickers VC-10&lt;/a&gt; all had paired engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, with the increasing airflow of high-bypass-ratio engines the interference between both will turn pairing into a disadvantage. In cruise, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose/9433#9433&quot;&gt;only the central stream tube flowing towards the engine will be ingested&lt;/a&gt;, and the rest will spill over the intake lip. Placing a second engine directly next to the first will block the flow of spilled air on that side and will increase spill flow on the opposite side. This will most likely cause massive separation there if the intake is not heavily modified, leading to noticeable drag increase. Also, the now asymmetric flow in the intake would reduce the efficiency of the fan - it needs very homogenous flow over the full cross section in today's engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, at low speed the engine &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;sucks in air from all around&lt;/a&gt; and will face competition from a second engine, such that both will not be able to ingest as much air as when mounted separately. The consequence of pairing would be reduced thrust during take-off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial disadvantage of separate engines, their collective impact on wing aerodynamics, is now greatly reduced by &lt;a href=&quot;https://aviation.stackexchange.com/questions/12109/why-do-we-use-pylons-to-mount-engine-on-jet-airliners&quot;&gt;mounting them on pylons&lt;/a&gt;, so they are ahead and below the wing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-08-23T22:14:45.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19212" PostTypeId="2" ParentId="19208" CreationDate="2015-08-22T19:01:12.723" Score="1" Body="&lt;p&gt;As well as the issues relating to the aerodynamics of the engine intakes and single-point-failures, the distance of the engines from the aircraft center-line affects the vibration frequencies of the wing and hence the flutter stability margin of the aircraft. That turned out to be a significant problem on the first version of the B747, to find a compromise position which could use three different engine types from the three engine manufacturers on a common wing design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first commercial jet airliner design addressed those problems by &quot;twinned engines&quot; buried in the wing root. For pictures see &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/De_Havilland_Comet&lt;/a&gt;. That design persisted in the derivative Nimrod military surveillance aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod&lt;/a&gt; until its recent retirement. The problems of trying to shoehorn a modern engine into that airframe configuration, and meeting modern safety standards (as opposed to 1950s era standards) was one of the problems which resulted in the proposed upgrade of the Nimrod MR2 to the MR4 to be abandoned (The MR2s were retired from service in 2011).&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-08-22T19:01:12.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19213" PostTypeId="1" CreationDate="2015-08-22T22:22:32.577" Score="6" ViewCount="193" Body="&lt;p&gt;Class B and Class C airspace has multiple rings where each ring can be a custom polygon shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mi6j8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mi6j8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to extract following data into text:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;the shape of these polygon rings in lat/long (ideally a geoJson object)&lt;/li&gt;&#xA;&lt;li&gt;distance between the rings and&lt;/li&gt;&#xA;&lt;li&gt;high / low limit for each ring&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Is this data available for free or purchase?&lt;/p&gt;&#xA;" OwnerUserId="9911" LastActivityDate="2015-11-18T19:06:41.493" Title="Class B and C Airpsace Ring Data in Text" Tags="&lt;airspace&gt;&lt;datasets&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2015-11-19T01:03:08.600" ContentLicense="CC BY-SA 3.0" />
  <row Id="19214" PostTypeId="1" AcceptedAnswerId="19223" CreationDate="2015-08-23T00:10:36.093" Score="51" ViewCount="19396" Body="&lt;p&gt;Looking at some videos and photos of &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;F/A-18 Hornets&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_F/A-18E/F_Super_Hornet&quot; rel=&quot;noreferrer&quot;&gt;Super Hornets&lt;/a&gt; taking off from carriers and from airfields, I recognised that the left rudder is pointing right, and the right rudder pointing left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JtYhn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JtYhn.jpg&quot; alt=&quot;Enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why is that? Are there any aerodynamic advantages?&lt;/li&gt;&#xA;&lt;li&gt;Is it also used as an airbrake to slow the plane down at landings?&lt;/li&gt;&#xA;&lt;li&gt;At which point of the flights are the rudders in this position and why? (Takeoff, landing, cruising, or both?)&lt;/li&gt;&#xA;&lt;li&gt;Does the pilot steer them or is the work done by a computer?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="14897" LastEditDate="2019-09-10T20:01:40.980" LastActivityDate="2020-06-19T19:37:47.623" Title="Why are the F/A-18 rudders deflected in opposing directions during takeoff?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;takeoff&gt;&lt;rudder&gt;&lt;f-18&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="19215" PostTypeId="1" CreationDate="2015-08-23T00:15:14.533" Score="2" ViewCount="6410" Body="&lt;p&gt;Are there 3 x AOA-sensors on all the Airbus family planes? In the Airbus flight manual there is one AOA-sensor called 'stand-by'. What does that mean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are all 3 AOA-sensors heated and can the actuall temperature of these sensors be monitored live by the pilots during flight?&lt;/p&gt;&#xA;" OwnerUserId="9912" LastEditorUserId="19" LastEditDate="2016-08-05T16:16:57.263" LastActivityDate="2016-08-05T16:16:57.263" Title="How many angle-of-attack sensors does the Airbus A 320 NEO have?" Tags="&lt;airbus&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19216" PostTypeId="2" ParentId="19214" CreationDate="2015-08-23T00:24:36.310" Score="5" Body="&lt;p&gt;It's the rudders acting like a ruddervator to assist in pitching up. This is possible because they lean outwards a bit.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-08-23T00:24:36.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19217" PostTypeId="1" AcceptedAnswerId="21050" CreationDate="2015-08-23T00:47:02.980" Score="14" ViewCount="9492" Body="&lt;p&gt;I am a computer programmer and student pilot. I want to make a computer program I can use to store my logs. Can I legally do this? Can I legally store Logbook endorsements with this? Are there any rules I need to be aware of? For the signatures can I use a pilot's certificate number instead?&lt;/p&gt;&#xA;" OwnerUserId="9619" LastEditorUserId="97" LastEditDate="2015-08-24T12:33:49.720" LastActivityDate="2020-09-04T04:37:56.190" Title="Is it legal to use an online logbook?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;&lt;software&gt;&lt;logbook-endorsements&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19218" PostTypeId="1" AcceptedAnswerId="19221" CreationDate="2015-08-23T01:20:06.903" Score="4" ViewCount="2157" Body="&lt;p&gt;I imagine certain fees from flight boarding sales are paid to the FAA, but who is responsible for paying fees for passenger flights?&lt;/p&gt;&#xA;" OwnerUserId="2245" LastActivityDate="2015-08-23T02:02:21.583" Title="Who pays for Air Traffic Control services?" Tags="&lt;faa-regulations&gt;&lt;passenger&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19220" PostTypeId="2" ParentId="19214" CreationDate="2015-08-23T01:38:20.517" Score="26" Body="&lt;p&gt;The rudders are deflected inwards during takeoff of the F/A-18E to help in raising the nose of the aircraft as it leaves the ship. As the vertical fins are canted outwards, deflecting both the rudders inwards generates a downforce, which, due to its location aft of the center of gravity, creates a pitch-up moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This position of rudders during takeoff is common to all F-18s, including the Canadian CF-18s, which are not used in carrier operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BTeWG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BTeWG.jpg&quot; alt=&quot;CF 18 takeoff&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: mybirdie.ca&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all aircraft with a canted tail (&lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor#Operational_history&quot; rel=&quot;noreferrer&quot;&gt;F22&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;noreferrer&quot;&gt;F35&lt;/a&gt;, etc.) can (and do) use their rudders for pitching in concert with elevators. The rudders are used during landing too. The principle is not much different and the FBW computer handles all these control surface operations usually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MhrhO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MhrhO.jpg&quot; alt=&quot;F-18 landing&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: reddit.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rudders are also used as airbrakes. The F18 had an airbrake, which was removed in F/A-18E/F, and the control surfaces are used as airbrakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/S0rup.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S0rup.jpg&quot; alt=&quot;F18 tailhook&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:FA-18_Trap.jpg#/media/File:FA-18_Trap.jpg&quot; rel=&quot;noreferrer&quot;&gt;FA-18 Trap&lt;/a&gt;&quot; by Original uploader was E2a2j at en.wikipedia - Transferred from en.wikipedia; transferred to Commons by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Mo7amedsalim&quot; rel=&quot;noreferrer&quot; title=&quot;User:Mo7amedsalim&quot;&gt;User:Mo7amedsalim&lt;/a&gt; using CommonsHelper.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rudders are in this position during takeoff/landing and once the aircraft is cruising, they become inline with the vertical tail to reduce drag. However, they can be used for decelerating the aircraft in flight, if required. Again, it is the computer which does the work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nLdMc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nLdMc.jpg&quot; alt=&quot;F22 speedbraking?&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: www.f-16.net/forum/&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2171" LastEditDate="2016-06-30T18:16:02.967" LastActivityDate="2016-06-30T18:16:02.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19221" PostTypeId="2" ParentId="19218" CreationDate="2015-08-23T02:02:21.583" Score="7" Body="&lt;p&gt;FAA Funding is currently a mix of General Fund(taxes everyone pays) and Airway Trust Fund(ticket taxes and fuel taxes) money. The breakdowns are shown in: &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/apl/aatf/media/AATF_Fact_Sheet.pdf&quot;&gt;https://www.faa.gov/about/office_org/headquarters_offices/apl/aatf/media/AATF_Fact_Sheet.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-08-23T02:02:21.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19222" PostTypeId="2" ParentId="19215" CreationDate="2015-08-23T02:34:18.593" Score="1" Body="&lt;p&gt;'#1 sensor data is displayed on the pilot's display by default, #2 sensor data is displayed on the co-captain's display by default, #3 sensor (stnd by) data is not displayed but is waiting for one of the other two to fail and it will display in the failed ones place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are all heated and active at all times and the pilot's can choose which ones to use on any display or flight control interface.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-08-23T02:34:18.593" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19223" PostTypeId="2" ParentId="19214" CreationDate="2015-08-23T03:10:23.017" Score="66" Body="&lt;h2&gt;Living Wing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Super Hornet has a living wing, that is to say, the shape of the wing is constantly in motion throughout every regime of flight. Trailing edge flaps, leading edge flaps, stabs, rudders, and ailerons all move in concert to give the pilot the greatest control during particular phases of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is evident by the use of the flaps switch. The three flap positions are, Auto (Up), Half, and Full. Up auto means that the flight control system (FCS) will dynamically change the wing based on what it thinks the pilot is trying to do. However, when the flaps switch is placed in the half and full positions the FCS switches to landing mode, and all flight control inputs will be interpreted as such. Even though the flaps switch has been placed to half/full, the pilot has only changed the FCS logic, he has not actually commanded the flaps to a fixed position. There are no fixed gains (flaps positions) like there are in typical commercial aircraft. Instead, the computer adjusts the flaps position to mimic a flaps half/full position, while also giving the pilot the most stable platform it can for landing. The logic has its limits though and if the pilot exceeds 14 AoA in a landing mode (flaps half or full), the FCS may accidently depart the jet. This is obviously bad 200&amp;nbsp;ft above the ground.  This switch commands the FCS to make flight control decisions and is the toggle between the tactical, and landing modes of flight.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Rudder Toe-In&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The particular effect you are referencing is called rudder toe-in. At slower speeds, particularly during high angles of attack, the stabilators may not provide sufficient nose authority to crisply rotate the nose. The massive wing area of the Rhino tends to block the airflow over the stabs. To remedy this problem the Rhino's rudders will automatically bias to the inside and create a downward force, which pitches the nose upwards. While the rudder is toed-in, the pilot can still use the rudders to yaw the aircraft. The FCS selectively moves the rudder position to generate the yawing motion, even while retaining the fared-in position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Take-off and Landing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During takeoff the rudder will remain in the toe-in position for a fixed 10 seconds after it detects weight off the wheels. This prevents the aircraft from accidentally faring the rudders (and losing nose authority) during one of the most critical phases of flight (AoA probe failures will actually cause the rudders to automatically fare, and this problem is removed by a fixed timing.) During the landing portion of flight, the rudders will also be fared in to give the aircraft more nose authority, and this is handled automatically by the FCS once the pilot commands the aircraft into landing mode by placing the flaps switch out of up auto.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Other Functions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the Rhino does have small speed brakes that extend during full speedbrake deployment, the primary method of increasing drag to rapidly slow the aircraft is through the use of the control surfaces. The FCS will increase the drag by lowering the flaps, toeing-in the rudders, lowing the ailerons, and deflecting the stabs, all while still giving the pilot a stable platform to fly the aircraft--it's an impressive aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During high alpha maneuvering, the Rhino will again deflect the rudders to the toed-in position while the flaps switch is in up auto. With the FCS logic in auto, the computers will attempt to retain control of the aircraft during max performance maneuvers, and will automatically schedule the flaps and rudders to compensate for high AoA and slow speed flight. Because the nose is cocked up and the airflow is disrupted over the stabs, the rudders will again create that pitching force that will assist the pilot in maintaining nose authority through any regime of flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Emergencies&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated before, there are times when the rudders may suddenly fare themselves which can have devastating effects during the final portion to land. Rudder failures are serious problems and should be treated as such.  Higher landing speeds and extra caution will be used, and the pilot should understand that wave offs may be impossible due to lack of nose authority in close to the ramp.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastEditorUserId="4215" LastEditDate="2015-08-24T03:10:04.060" LastActivityDate="2015-08-24T03:10:04.060" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19225" PostTypeId="1" AcceptedAnswerId="19230" CreationDate="2015-08-23T03:19:18.313" Score="21" ViewCount="4235" Body="&lt;p&gt;I know that go-arounds are pretty rare: somewhere around 2 per 1000 approaches. In large commercial aircraft the rate is probably even lower due to crew quality, instrumentation, conservative decisions etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But are there instances of multiple go-arounds having to be initiated by a flight crew on one flight? I'm just curious to hear of any such stories. Two GAs? Three GAs? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose if the reason is Weather related or equipment related the chance of a multiple go around might exist? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A related question is after how many weather related go-arounds would the crew decide to divert to the alternate. Either by rule, company procedure or plain heuristics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. Let's restrict this to non-training flights by scheduled airlines. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-11-14T08:51:02.497" LastActivityDate="2019-05-30T04:09:36.837" Title="Do multiple go-arounds on the same flight happen in commercial aviation?" Tags="&lt;commercial-aviation&gt;&lt;go-around&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19226" PostTypeId="2" ParentId="19215" CreationDate="2015-08-23T03:21:10.620" Score="2" Body="&lt;p&gt;I think there are three angle of attack sensors in all Airbus planes using fly-by-wire systems. The first two, which are arranged symmetrically near the nose are the main ones and the third one in the aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angle of attack data is not typically displayed to the pilot. The computer, on the other hand displays only stall warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angle of attack sensors are heated and active at  all times. The data from the sensors is received by the computer, compared (voted on) and displayed in the cabin.  The computer needs two values to agree for display.In case one fails or no two agree, the stall warning is lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main use of the angle of attack sensors is their use by the computers in calculating the characteristic speeds and for providing stall warning. I don't think the pilots can monitor. let alone control the heating of the AoA sensors.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-23T03:21:10.620" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19227" PostTypeId="2" ParentId="19225" CreationDate="2015-08-23T03:37:59.723" Score="4" Body="&lt;p&gt;Yes an aircraft occasionally perform multiple go-arounds. Sometimes weather(windshear the most common culprit) to ATC trying to squeeze out another departure or getting too close to the aircraft in front, necessitating a go around. General rule for multiple approaches, would be 2 or 3 before diverting to an alternate. A problem if you try to shoot too many approaches, is you start getting anxious and have a &quot;get there-its&quot; where you get so focused on getting on the ground you end up causing a major accident.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-08-23T03:37:59.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19228" PostTypeId="2" ParentId="19225" CreationDate="2015-08-23T03:42:20.513" Score="9" Body="&lt;p&gt;Multiple go-arounds are pretty rare, as already stated. However they do happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think &lt;a href=&quot;http://epaperbeta.timesofindia.com/Article.aspx?eid=31807&amp;amp;articlexml=Close-shave-Flight-lands-on-7th-attempt-with-22082015001080&quot;&gt;this&lt;/a&gt; takes the cake in go arounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the pilots of Boeing 737-800 (VT-JFA), flight 9W 555 from Doha to Kochi tried to land (and failed) for six times in two different airports (Kochi and Thiruvananthapuram) before finally landing in Thiruvananthapuram on the seventh attempt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.asianage.com/india/2-jet-airways-pilots-suspended-low-fuel-landing-504&quot;&gt;reports&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Despite the pilot having listed Bengaluru airport as the alternate airport to land, he instead chose to head for Thiruvanathapuram where he again made a “go-around” thrice over that airport which was also facing bad weather. Finally, left with not much of fuel, the pilot declared a fuel emergency and landed the aircraft at the airport there. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The flight was diverted from Kochi (after three landing attempts) due to bad weather. Reportedly, the flight has a reserve fuel of only 270kg (of the minimum requirement of 1500kg) at that point. Both the pilots ended up suspend by the regulatory authorities.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-23T03:42:20.513" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19229" PostTypeId="1" CreationDate="2015-08-23T04:17:08.027" Score="4" ViewCount="5164" Body="&lt;p&gt;In theory, if all 3 pitot tubes and all 3 AOA-sensors would fail simultaneously for a period of time, could the PFD still deliver correct roll angle and horizontal displays? How would the plane calculate the actual airspeed?&lt;/p&gt;&#xA;" OwnerUserId="9912" LastEditorUserId="1696" LastEditDate="2016-01-05T15:22:20.880" LastActivityDate="2019-03-29T06:41:32.387" Title="How would the Airbus A320 PFD respond to failure of all pitot and AOA sensors?" Tags="&lt;flight-instruments&gt;&lt;airbus&gt;&lt;sensors&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19230" PostTypeId="2" ParentId="19225" CreationDate="2015-08-23T04:17:08.497" Score="42" Body="&lt;p&gt;None of four airlines I worked for (two commuters, two Part 121) had specific guidance as to the max number of go-arounds. However, as mentioned in the other answers, 2 or 3 was believed to be a good rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only time I did multiple go-arounds, all missed approaches, was trying to get into Pullman, WA during a snowstorm in the late 1980s in an SA-227 Metroliner. I tried the VOR approach 3 times. Each time when we got down to the MDA, we did not have the forward visibility to descend further. Each of the 3 times the station personnel saw us pass over, and each time passengers looking out the windows saw the runway below us when we were overhead. That, of course, resulted in our being criticized when we arrived at our alternate by some passengers for not having landed at Pullman. I had explained en route to the alternate the problem with forward visibility, but when you've disrupted people's travel plans, they don't want to listen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I briefly considered the feasibility, when we were over the runway, of entering a tight left turn to see if I could keep the runway in sight, but I rejected that. And, yes, I considered descending below the MDA before catching sight of the runway. That would have been doable as I was very familiar with the airport and knew that the gently rolling fields around the airport topped out well below the MDA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem was that with all the snow on the ground and the snow in the air, we couldn't determine our altitude above the ground visually until we were actually over the runway. The fields around the airport had no trees, they were wheat fields in season. Even if I had chosen to bust the MDA, I still would have been too high for any kind of a normal landing when I caught sight of the runway end. If getting down was an emergency, we could have done it. It wasn't technically legal, but you could go into beta with the props and really drop out of the sky, then as you flared come out of beta. But it wasn't an emergency, so we went to our alternate, which was actually our next stop anyway, so all of the passengers weren't unhappy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage of multiple approaches is that conditions might get better while you're doing them, and you can get in. The disadvantage is that the nervous energy you're expending is telling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our SA-227s had no-autopilots, no radar altimeters, and, of course, no GPS. I imagine that these days that airport has one or more GPS approaches that would make landing in those conditions a piece of cake.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="12679" LastEditDate="2017-09-16T20:22:46.310" LastActivityDate="2017-09-16T20:22:46.310" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19231" PostTypeId="1" CreationDate="2015-08-23T04:34:50.490" Score="1" ViewCount="767" Body="&lt;p&gt;Direct Flight Law:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does the following characteristics exactly mean regarding sidestick input at a very low airspeed (let us assume near stall speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;'control sensitivity depends on airspeed'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Btw. is direct flight law only achievable with gear down and both FACs off?&lt;/p&gt;&#xA;" OwnerUserId="9912" LastEditorUserId="1696" LastEditDate="2016-05-25T14:17:59.937" LastActivityDate="2016-05-26T23:13:09.853" Title="In Airbus flight control laws what does it mean that &quot;control sensitivity depends on airspeed&quot;?" Tags="&lt;airbus&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19232" PostTypeId="1" CreationDate="2015-08-23T05:06:42.157" Score="11" ViewCount="4362" Body="&lt;p&gt;Is there any airspeed limit for deploying a ram air turbine? Can airspeed be determined from the rate of its propeller rotation? Could that data be used to determine altitude?&lt;/p&gt;&#xA;" OwnerUserId="9912" LastEditorUserId="22726" LastEditDate="2019-09-28T01:50:49.143" LastActivityDate="2019-09-30T19:05:11.970" Title="Is there a maximum airspeed to deploy a ram air turbine?" Tags="&lt;aircraft-systems&gt;&lt;emergency&gt;&lt;airspeed&gt;&lt;rat&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19233" PostTypeId="1" CreationDate="2015-08-23T05:16:17.433" Score="1" ViewCount="244" Body="&lt;p&gt;Do pitch control correction symbols exist in 'alternate law' and in 'direct law' mode (if planes angle of attack exceeds dangerously)?&lt;/p&gt;&#xA;" OwnerUserId="9912" LastEditorUserId="19" LastEditDate="2016-08-05T16:17:44.653" LastActivityDate="2016-08-05T16:17:44.653" Title="Does Airbus provide pitch control correction symbols outside &quot;normal law&quot;?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19234" PostTypeId="2" ParentId="19229" CreationDate="2015-08-23T05:17:27.370" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2317/1467&quot;&gt;AoA (Angle of Attack) vanes&lt;/a&gt;, as the name says, only measure the angle of attack, i.e. the angle between the velocity vector and the x-axis of the aircraft reference system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is used neither for roll angle measurements (the inertial units do that) nor for airspeed measurements (it is taken care of by the pitot tubes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if all 3 AoA sensors should fail simultaneously, the PDF could still display the artificial horizon and the airspeed correctly.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-08-23T05:17:27.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19235" PostTypeId="1" AcceptedAnswerId="19236" CreationDate="2015-08-23T09:31:23.447" Score="0" ViewCount="766" Body="&lt;p&gt;I heard that when an airplane is flying, air speed or air pressure is higher under the wings. Is it true?&lt;/p&gt;&#xA;" OwnerUserId="9915" LastEditorUserId="1467" LastEditDate="2015-08-23T13:04:36.157" LastActivityDate="2015-08-23T13:04:36.157" Title="Is the airspeed different between above and under the wings?" Tags="&lt;aerodynamics&gt;&lt;wind&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-08-24T10:56:42.027" ContentLicense="CC BY-SA 3.0" />
  <row Id="19236" PostTypeId="2" ParentId="19235" CreationDate="2015-08-23T10:29:35.737" Score="2" Body="&lt;p&gt;In case of a subsonic attached flow over the cambered airfoil (or a symmetric one at an angle of attack), the airflow speed is higher over the wing and pressure is lower. It is the other way around on the lower surface. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N51Sw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N51Sw.jpg&quot; alt=&quot;Airflow over the wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: virtualskies.arc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this is just the mechanics of the flow over the wing. This is &lt;em&gt;not&lt;/em&gt; an explanation of lift.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-23T10:29:35.737" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19237" PostTypeId="2" ParentId="19229" CreationDate="2015-08-23T11:02:17.627" Score="9" Body="&lt;p&gt;The primary flight display¹:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.oaviao.com/pesquisa_codigo_empresas/manuais_voo/performance_airbus/images/11.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nBu0s.gif&quot; alt=&quot;primary flight display&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;is a single display, but it shows &lt;strong&gt;five separate instruments&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On the left, the speed tape. This shows the value from the pitot probe.&lt;/li&gt;&#xA;&lt;li&gt;In the middle the attitude indicator. This shows attitude from gyroscopes. All gyroscopes are grouped in the “inertial reference unit”.&lt;/li&gt;&#xA;&lt;li&gt;On the right the big tape is altitude. This shows the value from the static port.&lt;/li&gt;&#xA;&lt;li&gt;The smaller tape at very right is vertical speed. It is normally taken from the inertial navigation system, which is part of the inertial reference unit, but can fall back to the static port.&lt;/li&gt;&#xA;&lt;li&gt;On the bottom is compass. This shows the value from the inertial reference unit, which has drift automatically compensated by reference to magnetometer.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The angle of attack is not displayed anywhere. It is only used for stall warning, as part of the alpha-protection logic and for checking the weight set in FMGC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all the instruments, each instrument shows value from &lt;em&gt;one&lt;/em&gt; input. The three pitot probes, static ports and inertial reference units each feed one of the three displays in the cockpit: captain's PFD, copilot's PFD and the standby instrument (which in the modern version looks like smaller PFD and is placed between captain's (left) displays and the centre display.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When any of the input fails, the computer will generate a warning (accompanied with the annoying cricket sound) stating that the values do not match, but it leaves it up to the pilots to determine which one is wrong. The pilots can then switch the displays to show the one they determined as trustworthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If all pitot probes failed, the speed would show nonsensical values, but the attitude, altitude and heading would remain operational. The system would fall back to alternate law. There is an unreliable airspeed procedure where the aircraft is kept in safe speed range by reference to attitude and vertical speed. Failure to execute that procedure properly was an important part in the accident sequence of &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;Air France flight 447&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;If the angle-of-attack vanes fail, the stall warning and alpha floor protection will not work, but all displays would work. However, the system may actually not notice that they failed as evidenced by the accident of &lt;a href=&quot;https://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T&quot; rel=&quot;noreferrer&quot;&gt;XL Airways Germany flight 888T&lt;/a&gt;. This was a test flight where they intentionally tried to activate the alpha-floor and it did not activate without any prior indication because the AoA-vanes froze due to improper wash.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ The image shown clearly is supposed to be Airbus PFD, but some elements like the protection indicators and the Mach number are missing. I just didn't quickly find better as this one is very readable.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-23T11:02:17.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19238" PostTypeId="2" ParentId="19231" CreationDate="2015-08-23T11:34:30.580" Score="4" Body="&lt;p&gt;In aircraft with mechanical controls, the position of the control column corresponds to position of the control surfaces and the force on the control column corresponds to the force on the control surfaces. At higher speeds, the same deflection generates larger force and correspondingly stronger response from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in Airbus the forces are not carried and the side-stick is spring-loaded. In normal law the side-stick deflection commands specific wing loading (which mostly corresponds to pitch rate) in pitch and roll rate in roll. So you get the same rate or pitch/roll with the same deflection independent of speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in direct law, the &lt;em&gt;position&lt;/em&gt; of the side-stick corresponds to the &lt;em&gt;position&lt;/em&gt; of the control surfaces. Because the same deflection causes larger aerodynamic forces, it leads to higher pitch/roll rate at higher speed. Significantly higher, because the control forces grow with &lt;em&gt;square&lt;/em&gt; of speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-23T11:34:30.580" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19239" PostTypeId="2" ParentId="19204" CreationDate="2015-08-23T13:40:44.283" Score="3" Body="&lt;p&gt;There is a requirement to &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/general-personnel-current-1810.htm&quot; rel=&quot;nofollow&quot;&gt;complete a flight review every two years&lt;/a&gt;. I guess it's technically just a 'FR' but for all intents and purposes it is a BFR! &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-08-23T13:40:44.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19241" PostTypeId="1" AcceptedAnswerId="19244" CreationDate="2015-08-23T17:43:04.617" Score="8" ViewCount="20505" Body="&lt;p&gt;To start off, &lt;a href=&quot;https://aviation.stackexchange.com/questions/14327/what-is-the-mechanism-by-which-condensation-forms-above-wings/&quot;&gt;yes this question was asked before&lt;/a&gt;, yet I don't find the answers satisfying and here is why:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to me that &lt;strong&gt;this phenomenon only appears during the approach phase&lt;/strong&gt; of a flight and during low speed turns, or rather when the &lt;strong&gt;angle of attack is rather high&lt;/strong&gt;. Also, usually the flaps are deployed when it happens, yet I'm not sure if that makes a difference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering this, &lt;a href=&quot;https://aviation.stackexchange.com/questions/14327/what-is-the-mechanism-by-which-condensation-forms-above-wings/14488#14488&quot;&gt;the answers&lt;/a&gt; wouldn't necessarily answer my question. They all talk about how there is a lower pressure above the wing, which causes the dewpoint to drop and thus makes the water condense. But is there a &quot;lower&quot; lower pressure when the angle of attack is higher and therefore making this phenomenon occur more often? Or is the point at which the laminar airflow gets turbulent (which moves forward as the aoa is increased) an important factor here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture to show what condensation I mean:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ch95S.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ch95S.jpg&quot; alt=&quot;shallow yet clearly visible clouds form on the wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a more extreme one:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Q78za.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q78za.jpg&quot; alt=&quot;This 757 (I think) is doing it right!&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2018-07-23T03:22:10.950" Title="Why does condensation form on the wing especially during take-off and landing?" Tags="&lt;aerodynamics&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19242" PostTypeId="1" AcceptedAnswerId="19247" CreationDate="2015-08-23T18:10:45.527" Score="11" ViewCount="2798" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2890/why-cant-an-airplane-stall-at-zero-g&quot;&gt;This question&lt;/a&gt; makes me wonder what happens at -1G.&lt;/p&gt;&#xA;&lt;p&gt;When the load factor of an aircraft increases above 1, the stall speed increases. As the load factor comes closer to 0, stall speed decreases and becomes &amp;quot;infinitely&amp;quot; low (basically 0 kts) as an aircraft can not stall at 0G. But what happens at a negative load factor?&lt;/p&gt;&#xA;&lt;p&gt;For example, during inverted flight the airfoil is still producing lift when the angle of attack is negative (enough).  Thus the stall speed should change and as the efficiency of a inverted wing is (almost definitely) not as high, I am assuming that the stall speed decreases.&lt;/p&gt;&#xA;&lt;p&gt;But is a negative G maneuver necessarily to be done in inverted flight? No!&lt;/p&gt;&#xA;&lt;p&gt;As a glider pilot,  I can refer to negative Gs during winch launches, or rather when they fail. You often practice cable fails, where your instructor disconnects you from the winch. To maintain speed and prevent a stall you push the nose down, ideally flying a small Zero-G parabola (as this will prevent a stall). But what if you push even more? Where is the stall speed going to be at?&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="7532" LastEditDate="2020-11-04T03:36:14.183" LastActivityDate="2020-11-04T03:36:14.183" Title="Is the stall speed different at -1G?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19243" PostTypeId="2" ParentId="19241" CreationDate="2015-08-23T18:12:02.273" Score="1" Body="&lt;p&gt;Let's remember for a second that on the upper side of the wings there is lower pressure than the free stream (air far from the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is travelling through humid air, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Adiabatic_process&quot; rel=&quot;nofollow&quot;&gt;adiabatic process&lt;/a&gt; (which all packets of air that end up near the wing have to &quot;suffer&quot;) dictates that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$P_{\infty} ^{(1-\gamma)} \cdot T_{\infty} ^\gamma = P_{wing} ^{(1-\gamma)} \cdot T_{wing} ^\gamma $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and since we just remembered that $P_{wing} &amp;lt; P_{\infty}$, it means that $T_{wing} &amp;lt; T_{\infty}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still from the wikipedia link above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Adiabatic cooling occurs when the pressure on an adiabatically isolated system is decreased, allowing it to expand, thus causing it to do work on its surroundings. When the pressure applied on a parcel of air is reduced, the air in the parcel is allowed to expand; as the volume increases, the temperature falls as internal energy decreases.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the initial $T_{\infty}$ was already low enough, or if there was enough umidity in the air, the packets of air above the wings finds themselves below the dew point, producing the condensation that prompted your question.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But is there a &quot;lower&quot; lower pressure when the angle of attack is higher and therefore making this phenomenon occur more often?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, higher angles of attack mean higher lift, that is generated by higher differential pressure between upside and underside of the wing. Remember that the lift is roughly &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L \propto \alpha \cdot V^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and since the weight of the aircraft is not reduced, to keep the lift constant at lower speeds (such as the speeds just before landing) you need an higher $\alpha$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To prevent the need of extreme angle of attacks, the effect of the flaps is to increase the $C_{l\alpha}$, meaning that for the same angle of attack you get more lift, changing the proportional relationship above.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-08-24T12:36:58.977" LastActivityDate="2015-08-24T12:36:58.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19244" PostTypeId="2" ParentId="19241" CreationDate="2015-08-23T18:12:38.330" Score="7" Body="&lt;p&gt;Yes, speed and flaps do make a difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift created by the wings is approximately constant over the duration of a flight. With full tanks, it is higher at the beginning of the flight, and when the aircraft banks, it is again higher to create the centripetal force for changing its course. But the difference is small¹.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is &lt;a href=&quot;https://aviation.stackexchange.com/questions/13957/does-the-downwash-created-by-induced-drag-increase-or-decrease-lift/13978?s=15%7C0.0855#13978&quot;&gt;caused by a pressure difference&lt;/a&gt; between the two sides of the wing. In cruise, this difference is low but extends over much of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5005/what-is-the-chord-of-a-wing&quot;&gt;wing's chord&lt;/a&gt;. At low speed, however, the suction on the top surface has a peak right aft of the leading edge, so the maximum suction is bigger than it is in cruise. Exactly this changed pressure distribution causes the humidity to condense, because it lets the air's relative humidity rise above the condensation point. In cruise, the pressure change is lower and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dew_point&quot; rel=&quot;nofollow noreferrer&quot;&gt;dew point&lt;/a&gt; is not exceeded. Also, since the airplane flies slower when close to the ground, the air has more time for the condensation to develop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See below for a color-coded plot of the speed distribution over a typical airliner airfoil in the landing configuration. Red symbolizes the lowest speed (highest pressure), while purple stands for the highest speeds with the lowest pressure. Such suction peaks must be avoided in cruise to enable the aircraft to fly at a high cruise Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MpcSd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MpcSd.jpg&quot; alt=&quot;Airliner airfoil with high lift devices in landing configuration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliner airfoil with high lift devices in landing configuration (picture &lt;a href=&quot;http://docs.desktop.aero/appliedaero/airfoils2/highlift.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;¹ The &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_fraction&quot; rel=&quot;nofollow noreferrer&quot;&gt;fuel fraction&lt;/a&gt; of airliners rarely exceeds 40%, and the added lift in a 30° bank is only 15%.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-24T07:25:41.037" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19245" PostTypeId="2" ParentId="19241" CreationDate="2015-08-23T18:16:35.350" Score="6" Body="&lt;p&gt;As the angle of attack increases, the pressure on the upper surface of the wing becomes lower. The following figure shows this. Note that the pressure on top is suction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DGyxl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DGyxl.jpg&quot; alt=&quot;Pressure change with AoA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: avstop.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the landing phase, the angle of attack of the aircraft is higher compared to to other regimes. This is the reason condensation clouds are formed during the landing phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the clouds are formed during any subsonic maneuver that reduced pressure over the upper surface of the wings, like high-g turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9LRdb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9LRdb.jpg&quot; alt=&quot;F 18 Condensation Cloud&quot;&gt;&lt;/a&gt;&#xA;Source:www.telegraph.co.uk&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-23T18:16:35.350" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19246" PostTypeId="2" ParentId="19231" CreationDate="2015-08-23T18:27:54.853" Score="2" Body="&lt;p&gt;As to the second part of your question, AFAIK the aircraft will only go into Direct Law or Alternate Law in the case of a malfunction, either in the physical control systems, sensors or computer systems. In the case of Direct Law all flight envelope protections are lost. Since the controls are not connected with cables in a FBW system you still need the FAC's since they are actually making your control inputs happen.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-23T18:27:54.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19247" PostTypeId="2" ParentId="19242" CreationDate="2015-08-23T19:31:54.063" Score="12" Body="&lt;p&gt;Only in aerobatic aircraft is the inverted stall speed identical to the upright stall speed in level flight. Airplanes registered in the Normal and Utility classes have cambered airfoils which have a higher positive maximum lift coefficient. In inverted flight, their stall speed is higher than their upright stall speed. The same goes for gliders and airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I had my last aborted winch launch in a ASK-13, I involuntarily checked how well the cockpit had been cleaned last time. I had to briefly close my eyes to avoid getting sand and dust into them. I can confirm that it is fully possible to fly a negative maneuver in upright position, albeit only briefly. However, the negative acceleration had as much to do with the rate of rotation and my position ahead of the cg as with negative lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I had pushed a lot more, I could had stalled the wing by undershooting the negative lift minimum. But this would had just limited the downward acceleration, and the negative lift would not had been sufficient for inverted flight, because the inverted stall speed in level inverted flight was most likely higher than the speed at the time of the tow line rupture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The negative stall speed is just your flight speed, and the possible negative gs grow with the square of speed. Stall is a matter of angle of attack, not of speed. A negative stall in upright attitude is rather uneventful - the aircraft will be at a high rate of rotation and will just hit the limit of downward acceleration.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-23T17:08:41.603" LastActivityDate="2016-05-23T17:08:41.603" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19248" PostTypeId="1" AcceptedAnswerId="19251" CreationDate="2015-08-23T19:47:00.483" Score="11" ViewCount="2669" Body="&lt;p&gt;Considering the delays and mishaps in super-projects (e.g. the new airport in Berlin), wouldn't it be rational to standardize airports in the same ways aircraft are: Building them all according to the same designs and not in a &quot;one-off&quot; fashion? Why is this not done?&lt;/p&gt;&#xA;" OwnerUserId="935" LastActivityDate="2015-10-05T23:18:06.430" Title="Why aren't airports built identically (like aircraft)?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19249" PostTypeId="2" ParentId="19248" CreationDate="2015-08-23T20:19:57.037" Score="12" Body="&lt;p&gt;You can standardize a procedure to determine the optimal airport, but this wont produce a constant shaped airport.  The biggest factors in airport construction are the runways.  Runways are influenced by&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;prevailing winds&lt;/li&gt;&#xA;&lt;li&gt;anticipated operations (volume and type) &lt;/li&gt;&#xA;&lt;li&gt;surrounding terrain&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If there is only one dominant prevailing wind direction you can get away with runways in one direction.  If you have a significant secondary prevailing direction, you'll need a crosswind runway.  If you want to handle lots of operations, you need multiple runways in the same direction.  To maximize operations you want them to be widely spaced apart.  If you want to handle large airplanes you need longer runways.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of those factors (and more) will determine an optimal runway layout, but practical considerations (mostly finite available space) will turn the optimal layout into something else.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This procedure means a one-airport-fits-all solution isn't very realistic.  This also only applies to new construction (see: KDEN).  Many airport construction projects are also limited by the existing airport they are expanding and the development around them.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-08-23T20:39:29.000" LastActivityDate="2015-08-23T20:39:29.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19250" PostTypeId="2" ParentId="16690" CreationDate="2015-08-23T20:24:23.710" Score="2" Body="&lt;p&gt;&lt;strong&gt;5. &quot;Travel-agent&quot; airline&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Travel-agent&quot; airline stands for airlines owned and operated by the travel agents. It often refers as &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_charter&quot; rel=&quot;nofollow noreferrer&quot;&gt;charter airline&lt;/a&gt;, but in this case the lessee and lessor are same company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The business model of &quot;Travel-agent&quot; airline looks like LCC. They usually provides homogeneous seats; their ticket are only available through their companies; their routes mainly focus on short/medium distance, but with some long tourist cities (like Bangkok) in busy seasons (Summer holiday/Christmas).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, they often provide free checked luggage allowance and sometimes free meal. Their seats are generally wider and larger; personal entertainment system may be installed for each passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thomas_Cook_Airlines&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thomas Cook airlines&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Thomson_Airways&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thomson Airways&lt;/a&gt; are tow largest &quot;Travel-agent&quot; airline in UK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ov6Si.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ov6Si.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-08-23T20:24:23.710" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19251" PostTypeId="2" ParentId="19248" CreationDate="2015-08-23T21:05:53.877" Score="29" Body="&lt;p&gt;&lt;strong&gt;1. Terrain and land use&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several new airports are build on landfill island or coast next to mountains, their shape is influenced by the terrain and their size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Hong_Kong_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Hong Kong International Airport&lt;/a&gt; runways and shape are influenced by the terrain. Its curved east bank looks like the Chek Lap Kok island, which the airport is built on there. Both HKIA runways are parallel to the hill of Lantau island, south of the airport island.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HKIA is on the north of Lantau island (largest green shape), the grey colour stands for reclamation land and the green colour is the originally &lt;a href=&quot;http://www.amo.gov.hk/en/oe_lantau_island.php&quot; rel=&quot;noreferrer&quot;&gt;Chek Lap Kok&lt;/a&gt; island.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1L29z.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1L29z.png&quot; alt=&quot;Map of Lantau island showing reclaimed land&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. Prevailing wind&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Prevailing winds influence the runway heading. Since takeoffs and landings are usually done as close to headwind as possible, wind direction generally determines the active runway. If the prevailing wind is uncertain, multiple runways with different directions will be built, &lt;a href=&quot;https://en.wikipedia.org/wiki/Logan_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Boston Logan airport&lt;/a&gt; is a extreme example.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/7kVhC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7kVhC.jpg&quot; alt=&quot;Aerial view of Boston Logan airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. Terminal building and bargaining power of airport management&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This factor largely influences the terminal layout. In USA the airport management is largely influenced by the airlines, sometimes the terminal buildings are managed by airlines themselves, like &lt;a href=&quot;https://en.wikipedia.org/wiki/John_F._Kennedy_International_Airport#Terminals&quot; rel=&quot;noreferrer&quot;&gt;New York JFK&lt;/a&gt;. The airlines prefer the terminal building which can minimize the taxiing time, passengers transfer time and maximize the perimeter (and hence the number of gates), &lt;a href=&quot;https://en.wikipedia.org/wiki/Hartsfield%E2%80%93Jackson_Atlanta_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Atlanta Hartsfield airport&lt;/a&gt; is one good example. Its linear shape can minimize the taxiing time and increase the number of gates available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RicDS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RicDS.jpg&quot; alt=&quot;Map of terminals at Atlanta Hartsfield&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, for main airports outside USA and Europe, the airport owner has strong marginal power of the airport management. They will choose the terminal building which can best fit for their strategy. Some airports owned by the government prefer a massive size of airport as an image of the country/cities; and some airports prefer large commons which can maximize the shopping experience (and hence rental income). Pictured below is Beijing Capital International Airport.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aGKma.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aGKma.jpg&quot; alt=&quot;Nighttime aerial view of Beijing Capital International Airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4. Historical factor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several airports were built before World War II and some even existed before World War I. At that time the airport was just a new concept. A full development and operation methodology for airport had not been developed. Many full airport layouts, which nowadays seem to be &quot;inefficient&quot;, were developed. And since the layout with the buildings were built, it is costly and time-consuming for reconstruction, especially at the busiest airports. Airport managers tends to expand the existing building with new gates and other facilities, rather than total reconstruction. Pictured below is a master plan for O'Hare International Airport from 1948.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nXWCm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nXWCm.jpg&quot; alt=&quot;Master plan for O&amp;#39;Hare International Airport from 1948&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heathrow airport is reconstructing Terminals 1-3, replaced by linear buildings like Terminal 5. It will take 5 years to destroy the old Terminal 2 and phase one was just completed last year. Terminal 3 will be rebuilt after 2019 and the whole project will take more than a decade.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZKnuu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZKnuu.jpg&quot; alt=&quot;Illustrated aerial view showing Heathrow expansion plans&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;5. Airport operation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operations of the airport are influencing the airport layout. For airports have more flights for both general aviation and airlines, they tend to have more runways, like &lt;a href=&quot;https://en.wikipedia.org/wiki/Dallas/Fort_Worth_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Dallas DFW&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Amsterdam_Airport_Schiphol&quot; rel=&quot;noreferrer&quot;&gt;Amsterdam Schiphol&lt;/a&gt;. On the other hand, in most parts of the world there are only 1 or 2 runways even for the most busiest airports where most of the flights are from airliners, like Dubai and Hong Kong, ranking for 6th and 10th busiest airport in terms of total passengers.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Hyq56.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hyq56.jpg&quot; alt=&quot;Aerial view of Dubai International Airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;6. Reversal: Experience&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, huge number of airports has been built in the half century, several airport design has been well developed. We can see the latest airport may share similar terminal shape, runway plan and airport layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hong Kong international airport and Hamad International airport&#xA;&lt;a href=&quot;https://i.stack.imgur.com/t6fHT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t6fHT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chongqing airport (Far future) and New Lisbon airport proposal&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9GfK0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9GfK0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sum up, there is not one optimal conclusion of airport layout. The airports are built related to physical limitation, historical constraints, stakeholders opinions, and, of course, the architects' designs. No airport will be identical, regardless the layout, terminal shape and style. On the other hand, the experience from airport planner will create a similar airport.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-10-05T23:18:06.430" LastActivityDate="2015-10-05T23:18:06.430" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19252" PostTypeId="1" AcceptedAnswerId="19253" CreationDate="2015-08-23T21:21:37.293" Score="3" ViewCount="7252" Body="&lt;p&gt;I've recently started studying for my Air Law and Meteorology exam and am trying to get my head around some of the basic literature / legal documentation structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it the Chicago Convention outlined a series of ICAO Articles that are available in detail as Annexes. These are introduced into law in the UK via the Air Navigation Order.&#xA;I'm having some confusion understanding the AIP and how this relates back to the ANO, if at all. Not only this but also what the main differences between an AIP, AIC and NOTAM are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is anyone able to help by concisely explaining how these entities relate to one another and how they differ so that I can build a mental image before studying each further, I would greatly appreciate it.&lt;/p&gt;&#xA;" OwnerUserId="9920" LastEditorUserId="3201" LastEditDate="2015-08-24T07:30:46.913" LastActivityDate="2018-06-28T09:31:07.400" Title="AIP, AIC, NOTAM, ANO (UK): How do they relate to Annex 15 of Chicago Convention?" Tags="&lt;general-aviation&gt;&lt;notam&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19253" PostTypeId="2" ParentId="19252" CreationDate="2015-08-24T06:34:08.257" Score="4" Body="&lt;p&gt;Annex 15 of ICAO Chicago convention describes the required information for safe conduct of flights, and which aeronautical information is to be provided by ICAO members. Each country needs to provide an aeronautical information service (AIS) in a standardized form, comprising static and dynamic data.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Static: Aeronautical information publication (AIP), AIP amendments and charts. AIP is generally updated each 28 days.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dynamic: Notam, AIP supplements.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Explanatory information doesn't fit well in the previous categories, and is grouped in aeronautical information circulars (AIC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;AIP: Authoritative information issued by an ICAO member containing long lasting aeronautical information essential to air navigation.&lt;br&gt;&lt;a href=&quot;http://gis.icao.int/gallery/ONLINE_AIPs.html&quot; rel=&quot;nofollow&quot;&gt;AIP list by country&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;AIP amendment:  Permanent change to AIP.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;AIP supplement: Temporary change to AIP.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Notam (and Snowtam): Notice distributed by a telecommunication system, concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations. Also associated with Notam: pre-flight information bulletin (PIB), a presentation of current Notam information of operational significance, prepared prior to flight.&lt;br&gt;&lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/noticesAction.do?queryType=ALLTFR&amp;amp;formatType=ICAO&quot; rel=&quot;nofollow&quot;&gt;Notams in US&lt;/a&gt;.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;AIC: Information that doesn't qualify for inclusion in AIP or Notams but which relates to flight safety, air navigation, technical, administrative or legislative matters. This could include mid-term prevision for changes in the regulatory or technical frameworks, results of safety investigations, scientific discovery related to how weather impacts aviation...&lt;br&gt;&lt;a href=&quot;http://www.navcanada.ca/EN/products-and-services/Pages/AIP-part-5-current.aspx&quot; rel=&quot;nofollow&quot;&gt;List of Canada AIC&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Full aeronautical information contains: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;AIP, including amendments  &lt;/li&gt;&#xA;&lt;li&gt;Supplements to the AIP&lt;/li&gt;&#xA;&lt;li&gt;Notams&lt;/li&gt;&#xA;&lt;li&gt;AIC&lt;/li&gt;&#xA;&lt;li&gt;Checklists and lists of valid Notams. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Source for the above definitions: &lt;a href=&quot;http://www.aai.aero/public_notices/AIS.pdf&quot; rel=&quot;nofollow&quot;&gt;Manual of Aeronautical Information Services, India&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Regarding The Air Navigation Order (ANO), specific to UK&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;On 7 December 1944, the majority of the world's nations became&#xA;  signatories to the &quot;Chicago Convention&quot;, the aim of which was to&#xA;  assure the safe, orderly and economic development of air transport.&#xA;  ICAO sets out, in the terms of the convention, the rules, regulations&#xA;  and requirements to which each signatory must adhere. The Civil&#xA;  Aviation Act 1982 is the UK's means of discharging its ICAO&#xA;  responsibilities. This legislation required the creation of the CAA.&#xA;  The Air Navigation Order (ANO) is the law that empowers us to carry&#xA;  out our duties.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.caa.co.uk/default.aspx?catid=1404&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ANO is the legal framework valid for UK, to empower aeronautical agencies and their publications, in accordance with Annex 15.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-08-24T06:34:08.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19254" PostTypeId="1" CreationDate="2015-08-24T09:31:14.183" Score="6" ViewCount="1952" Body="&lt;p&gt;Are engine failures practiced normally? What exactly are the reasons? Is there a particular type of failure that is required training for all pilots worldwide?&lt;/p&gt;&#xA;" OwnerUserId="870" LastEditorUserId="487" LastEditDate="2015-08-26T01:17:00.150" LastActivityDate="2017-03-31T17:51:57.980" Title="Does one have to practice engine failures in flight training?" Tags="&lt;flight-training&gt;&lt;engine-failure&gt;" AnswerCount="3" CommentCount="15" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19255" PostTypeId="2" ParentId="19202" CreationDate="2015-08-24T10:01:43.860" Score="3" Body="&lt;p&gt;A benefit that the A380 has in terms of drag is its size.&#xA;As the aircraft is very large, the Reynolds numbers appearing on the wing are larger. &#xA;For a turbulent boundary layer on a hydraulically smooth plate, Schlichting$^{[1]}$ proposes the following approximate relation for the Turbulent friction coefficient, $C_f$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ C_f=\frac{0.0472}{(log_{10} Re)^{2.58}} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shows that for increasing the value of $Re$, the value of $C_f$ decreases.&#xA;As such, a larger wing will lead to a lower friction coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that the total friction drag might still increase with increasing wing size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1] Schlichting, H., Gestern, K.: Boundary Layer Theory, 8th edn. Springer, Berlin (1999)&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-08-24T13:40:00.227" LastActivityDate="2015-08-24T13:40:00.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19256" PostTypeId="1" AcceptedAnswerId="19263" CreationDate="2015-08-24T11:51:54.700" Score="2" ViewCount="1367" Body="&lt;p&gt;Most airliners have 3 or 4 shock bodies to reduce wave drag. But why can't there be more anti-shock bodies per wing?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1467" LastEditDate="2015-08-24T11:56:30.210" LastActivityDate="2017-08-01T08:39:49.057" Title="Why can't there be more than 4 anti-shock bodies on each wing?" Tags="&lt;airliner&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19257" PostTypeId="1" CreationDate="2015-08-24T12:00:30.967" Score="8" ViewCount="2566" Body="&lt;p&gt;I know the B747-8 uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Electro-hydraulic_actuator&quot; rel=&quot;noreferrer&quot;&gt;electro-hydraulic actuators&lt;/a&gt; as does the 787, but what about the 737 MAX?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1289" LastEditDate="2015-08-24T13:33:06.527" LastActivityDate="2019-03-12T00:11:34.047" Title="Does the Boeing 737 MAX use electro-hydraulic actuators?" Tags="&lt;boeing-737&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19259" PostTypeId="2" ParentId="19225" CreationDate="2015-08-24T12:34:28.090" Score="3" Body="&lt;p&gt;I once had a flight in region NSW (Australia) in bad weather. We had 3 go arounds at destination, then diverted to another, 2 go arounds then diverted again, 2 more go arounds and eventually went back to original airport and landed first attempt. We were very late and they had to get another plane to take us on to sydney... long time ago though&lt;/p&gt;&#xA;" OwnerUserId="9929" LastActivityDate="2015-08-24T12:34:28.090" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19260" PostTypeId="1" AcceptedAnswerId="19262" CreationDate="2015-08-24T12:40:25.000" Score="10" ViewCount="1037" Body="&lt;p&gt;Based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/19214/f-a-18-rudder-position-during-takeoff&quot;&gt;this&lt;/a&gt; question about the rudder position of the F/A-18 Fighter Jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quote from the user Rhino Driver:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The logic has its limits though and if the pilot exceeds 14 AoA in a landing mode (flaps half or full), the FCS may accidently depart the jet. This is obviously bad 200 ft above the ground.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As stated before, there are times when the rudders may suddenly fare themselves which can have devastating effects during the final portion to land. Rudder failures are serious problems and should be treated as such.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Are there any known incidents where the pilot (as example) exceeded 14 AoA in landing mode and the FCS accidently departed the jet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FCS has to play a certain role in the incident (like in the example) or like the incident No. 3 from the user aeroalias.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-08-05T16:19:02.200" Title="Are there any incidents caused by rudder failure in Military jets?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;military&gt;&lt;rudder&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19261" PostTypeId="2" ParentId="19233" CreationDate="2015-08-24T13:54:50.000" Score="2" Body="&lt;p&gt;You may be confusing the operation of the autopilot, the envelope protections and the flight director.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AIUI, the job of the flight director is to indicate the required roll angle and pitch to achieve a new compass heading and/or new altitude that the pilot has selected on the FD. If the AP is engaged, the FD will cause the AP to make the appropriate control movements, otherwise the pilot has to make the control inputs suggested on the FD display.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has nothing to do with flight envelope protections AFAIK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Alternate Law the Flight Director can still be visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The BEA identified misuse of the FD as a possible factor in the loss of AF447 &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;as the flight control law switched from normal to alternate, the flight director’s crossbars disappeared. But they then reappeared several times. ... PF may have trusted the flight director so much that he was verbally agreeing to the other pilot’s pitch-down instructions, while still actually pitching up.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ainonline.com/aviation-news/2012-07-08/final-af447-report-suggests-pilot-slavishly-followed-flight-director-pitch-commands&quot; rel=&quot;nofollow&quot;&gt;AIN online&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Disconnection of the flight director is normally part of the &quot;unreliable airspeed&quot; procedure. But after the A330 lost its airspeed information, and the autopilot and autothrust automatically disconnected, the crew left the flight directors engaged.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flightglobal.com/news/articles/airbus-reviews-instrument-logic-in-aftermath-of-af447-374484/&quot; rel=&quot;nofollow&quot;&gt;FlightGlobal&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-24T14:18:45.183" LastActivityDate="2015-08-24T14:18:45.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19262" PostTypeId="2" ParentId="19260" CreationDate="2015-08-24T14:10:10.563" Score="5" Body="&lt;p&gt;There are certainly a large number of incidents/accidents in military jets involving rudders. I've listed a few cases, not necessarily in takeoff/landing.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A Block 25 F-16C suffered structural failure during flutter tests with the AMRAAM missile. The rudder delaminated and tore off, and the pilot managed to land the aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rkRbj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rkRbj.jpg&quot; alt=&quot;F-16 with rudder and flaperon damage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: f-16.net&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;B-52 vertical stabilizers were prone to failure during operation at low altitudes. While under testing, a B-52H suffered catastrophic failure of vertical stabilizer. The pilots managed to land the aircraft with help from Boeing test engineers.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KriFx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KriFx.jpg&quot; alt=&quot;B-52 with most vertical fin missing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Boeing_B-52_with_no_vertical_stabilizer.jpg#/media/File:Boeing_B-52_with_no_vertical_stabilizer.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing B-52 with no vertical stabilizer&lt;/a&gt;&quot; by United States Air Force - USAF. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in other &lt;a href=&quot;https://en.wikipedia.org/wiki/1963_Elephant_Mountain_B-52_crash&quot; rel=&quot;nofollow noreferrer&quot;&gt;cases&lt;/a&gt;, the same failure caused fatal crashes.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;A USAF investigation blamed &lt;a href=&quot;http://archives.starbulletin.com/2008/05/07/news/story06.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;rudder failure&lt;/a&gt; for the loss of an F-15 near Hawaii in 2008. The investigation concluded that most probably both rudders in the jet failed due to failure of the aileron-rudder interconnect.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;F-14 suffered from rudder hardover &lt;a href=&quot;http://www.flightglobal.com/news/articles/us-navy-works-on-f-14-rudder-problem-137251/&quot; rel=&quot;nofollow noreferrer&quot;&gt;incidents&lt;/a&gt;, one of which lead to loss of the aircraft. &lt;a href=&quot;http://oai.dtic.mil/oai/oai?verb=getRecord&amp;amp;metadataPrefix=html&amp;amp;identifier=ADA393597&quot; rel=&quot;nofollow noreferrer&quot;&gt;Investigations&lt;/a&gt; found the reason was due to mechanical failure of a stop plate attached to the hydraulic actuator.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-08-24T15:52:33.053" LastActivityDate="2015-08-24T15:52:33.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19263" PostTypeId="2" ParentId="19256" CreationDate="2015-08-24T14:24:58.830" Score="13" Body="&lt;p&gt;There is no reason to limit the number of anti-shock bodies to 3 or 4. In most modern aircraft, the anti-shock bodies are the flap track fairings which usually house the flap mechanisms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such, their number is determined by among other things, the wingspan, the size of control surfaces and the number of actuators required for their actuation etc. This usually limits their number to around 4 due to weight and other considerations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there is no reason there should only be 3 or 4 of them. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-225_Mriya&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-225 Mriya&lt;/a&gt; has a whole lot of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AejqR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AejqR.jpg&quot; alt=&quot;http://i.stack.imgur.com/AejqR.jpg&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source:www.avioners.net&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-24T20:49:03.660" LastActivityDate="2015-08-24T20:49:03.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19264" PostTypeId="2" ParentId="19256" CreationDate="2015-08-24T15:07:09.110" Score="7" Body="&lt;p&gt;There can be, as aeroalias already demonstrated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it would not be better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transsonic flow behaves strangely. It cares more about the total cross-section than its distribution. So for the wave-drag reduction it does not matter much whether there are two larger or many smaller anti-shock bodies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However more anti-shock bodies with the same total cross-section have more surface area and higher surface area causes more friction drag. So more anti-shock is not advantageous.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-24T15:07:09.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19265" PostTypeId="1" AcceptedAnswerId="19269" CreationDate="2015-08-24T16:13:21.300" Score="17" ViewCount="4648" Body="&lt;p&gt;I was up this past weekend on my first solo cross country and decided to request VFR flight following and was a bit confused at what happened. For this question I will set up the actual situation as an example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was over the &lt;a href=&quot;http://www.pilotnav.com/navaid/faa-2046&quot;&gt;Pottstown VOR (PTW)&lt;/a&gt; heading to &lt;a href=&quot;https://www.airnav.com/airport/KLNS&quot;&gt;Lancaster (KLNS)&lt;/a&gt; on the 269 radial. I decided to call &lt;a href=&quot;https://www.airnav.com/airport/KRDG&quot;&gt;Reading (KRDG)&lt;/a&gt; approach for flight following as they were the closest approach or so I thought. They informed me that I was still in the Philadelphia airspace and advised to contact them. Now in the past (with my instructor) on the same flight in just about the same location we had taken flight following from Reading approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do you know who to hail for flight following?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was in the Philadelphia Mode C veil, is that why they sent me to Philly Approach?     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-24T17:03:48.660" LastActivityDate="2018-12-27T23:44:11.267" Title="Who to call for flight following?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19266" PostTypeId="1" AcceptedAnswerId="19268" CreationDate="2015-08-24T18:22:00.990" Score="8" ViewCount="9850" Body="&lt;p&gt;Is it recommended to intercept the ILS glideslope from above? Are there any special considerations like unstable approaches or GPWS warnings?&lt;/p&gt;&#xA;" OwnerUserId="9458" LastEditorUserId="3386" LastEditDate="2019-09-03T09:14:36.383" LastActivityDate="2019-09-03T09:14:36.383" Title="Can the ILS glideslope be intercepted from above?" Tags="&lt;instrument-procedures&gt;&lt;pilot-technique&gt;&lt;ils&gt;&lt;glideslope&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="19267" PostTypeId="2" ParentId="19266" CreationDate="2015-08-24T19:28:46.843" Score="3" Body="&lt;p&gt;If you mean the glide slope (vertical guidance) rather than the localiser (horizontal guidance), then you should capture from below.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is because if you capture from above, you must be descending and there is a risk, particularly if you capture the glide slope late, that you will descend below it.  This is a Bad Thing™.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approach, if followed, or ATC vectoring will bring you onto the localizer (horizontal guidance) at an angle, typically 30 degrees or so. You capture the localizer signal first, then then fly at a fixed altitude until you capture the glide slope, at which point you start descending.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="64" LastEditDate="2015-08-24T20:02:42.473" LastActivityDate="2015-08-24T20:02:42.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19268" PostTypeId="2" ParentId="19266" CreationDate="2015-08-24T20:22:39.423" Score="21" Body="&lt;p&gt;Assuming that you're asking about intercepting the glideslope from above rather than the localizer, the answer is that it is definitely NOT recommended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are at least two significant problems if you do this. First, is the fact that at high vertical angles there can be false glideslopes. Looking at the diagram below, if you're coming at the glideslope from above and the needle starts to move, are you intercepting the real 3&amp;deg; glideslope or the false 9 &amp;deg; glideslope?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KLqiQ.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KLqiQ.gif&quot; alt=&quot;False glideslope image&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The diagram above is the best I could find, but it has one error. It shows a &quot;Flag no signal&quot; at 6&amp;deg;. Actually what you'll have there is another false glideslope, but one which has reverse sensing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can, of course, do a reasonability check if you know your distance from the runway, or you could compare your vertical speed if following it with what you know your vertical speed should be, or on the 6&amp;deg; line a command to go up when you know you should go down would be a hint, but it's unwise in my opinion to put yourself in a situation that increases your work load that much during an instrument approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You asked about GPWS warnings. None of the aircraft I flew that had GPWS would sound a GPWS warning just from receiving a false glide slope. However, all of them would have sounded the GPWS if you followed a false glideslope and were close to the ground because doing so would give you an excessive sink rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second problem with approaching from above is that the vertical angular width of the glideslope as measured from needle full down to needle full up is very small. As I remember only about one degree. Whatever it is, though, the point is that if you descend into the glideslope with a vertical speed of only a few hundred feet per minute greater than the glideslope itself is descending, the needle is going to go from full down to full up very quickly. Without working it out, I'd guess that if you're inside the outer marker you might well miss its movement if your instrument scan had you away from the needle more than a second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the late 1970s a friend of mine was flying a charter in a Cessna 310. He unwisely decided to intercept the glideslope at Salem, Oregon from above. The aircraft hit the ground in the vicinity of the outer marker, killing all aboard. During the accident investigation, the NTSB found from radar data that he had a descent rate greater than 1,000 fpm going through the glideslope.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-08-25T21:02:41.120" LastActivityDate="2015-08-25T21:02:41.120" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="19269" PostTypeId="2" ParentId="19265" CreationDate="2015-08-24T21:05:01.383" Score="17" Body="&lt;p&gt;When you request flight following generally you contact the facility (either approach or center) responsible for the airspace you're in, so your real question is &lt;strong&gt;&quot;How the heck do I know whose airspace I'm in?!&quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer can usually be found on the charts, or in other FAA publications.&lt;br&gt;&#xA;Let's look at your example (&lt;em&gt;I was over the Pottstown VOR (&lt;code&gt;PTW&lt;/code&gt;) heading to Lancaster (&lt;code&gt;KLNS&lt;/code&gt;) on the 269 radial.&lt;/em&gt;) in detail with some convenient visual aids.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Preflight Planning and the A/FD&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You don't tell us what airport you took off from, but I'm going to assume &lt;code&gt;KPTW&lt;/code&gt; (Heritage Airport) as a convenient starting point.&lt;br&gt;&#xA;If we have a look in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/&quot; rel=&quot;noreferrer&quot;&gt;Airport/Facility Directory&lt;/a&gt; for &lt;code&gt;KPTW&lt;/code&gt; we'll get an answer very quickly from the &quot;Communications&quot; section:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4pDJY.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4pDJY.png&quot; alt=&quot;KPTW A/FD entry&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;&lt;pre&gt;&lt;code&gt;PHILADELPHIA APP/DEP CON 126.85 (800-354-9884)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if we're planning a flight out of KPTW and intend to pick up flight following our call to ATC should be made to Philadelphia Approach, on 126.85 (and if we're going IFR and need to talk to them on the ground there's a convenient phone number).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have an application like Foreflight or Garmin Pilot this information is readily available to you in the cockpit as well, so if you're unsure who to contact you can always pull up the A/FD information for the nearest airport and use that as a starting point.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;In-Flight - Using the Charts&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Let's say you didn't remember to look in the A/FD to see who you needed to talk to while you were on the ground, and the battery in your iPad is dead so Foreflight is out of the picture in the air. You can pull out your paper charts and get most of the same information in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we plot &lt;code&gt;PTW ... KLNS&lt;/code&gt; it puts you on the very bottom of the New York Sectional Chart, and on the Philadelphia Terminal Area Chart for part of the flight, so let's take a closer look at the route on each of those.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First the New York Sectional:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/E4kgc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E4kgc.jpg&quot; alt=&quot;New York Sectional&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Not much help here - or at least nothing glaringly obvious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the Philadelphia TAC:&lt;br&gt;&#xA; &lt;a href=&quot;https://i.stack.imgur.com/qgIhf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qgIhf.jpg&quot; alt=&quot;Philadelphia TAC&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;AHA! There are helpful white boxes with blue text on this chart that tell you &lt;code&gt;CTC PHILADELPHIA APP ON&lt;/code&gt; and list frequencies, altitudes, and active runways.&lt;br&gt;&#xA;This looks promising: Since the little box says to contact Philadelphia Approach that's who you should probably call first.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your case there happen to be &lt;em&gt;two&lt;/em&gt; helpful boxes, one above your route of flight and one below it. Both boxes are roughly equidistant from the route of flight, so it's not obvious which one you should pay attention to.   In cases like this you can call on either frequency (at least you're calling the right &lt;em&gt;facility&lt;/em&gt; - they may make you call on a different frequency and talk to another controller, but you're in the right neighborhood at least.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/o45cU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o45cU.jpg&quot; alt=&quot;Philadelphia TAC with both boxes shown&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also go to the Airport/Facility Directory (A/FD) as a tie-breaker (though you're probably less likely to pull the book out mid-air, and if you &lt;em&gt;did&lt;/em&gt; you'd probably use the nearest airport like I described above).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blue boxes are talking about the Philadelphia Class B airspace, so if we look at the entry for the Class B airport (Philadelphia International - &lt;code&gt;KPHL&lt;/code&gt;) we'll get more details on which radio frequencies we should use:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/IhucP.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IhucP.png&quot; alt=&quot;A/FD Clipping&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;If you're flying along the 269 radial from &lt;code&gt;PTW&lt;/code&gt; you're somewhere &quot;northwest of the airport&quot;, so you would call Philadelphia Approach on 124.35 / 128.4 if you're above 5,000 feet, or 126.85 (the same frequency we got from the A/FD entry for &lt;code&gt;KPTW&lt;/code&gt;)if you're below 5,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;I'd Like To Phone A Friend&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There's one final way to figure out who you should talk to, and that's to call someone else and ask. If you're opening your flight plan with Flight Service over the radio they will usually sign off with &quot;For flight following try Philadelphia Approach on 126.85&quot; and the usual plea for PIREPS, and if they don't offer a frequency you can always ask them. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-24T21:05:01.383" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19270" PostTypeId="1" AcceptedAnswerId="19272" CreationDate="2015-08-24T21:05:43.540" Score="3" ViewCount="2334" Body="&lt;p&gt;Let's show what I mean on an example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying towards a VOR (not knowing the distance), HSI course pointer pointing&lt;br&gt;&#xA;   towards the VOR. Let's say the plane is really far from the VOR and we turn&#xA;   the course pointer 5 degrees (no matter what way) CDI will move to one side&#xA;   (far because of the distance). If the plane was close to the VOR and we turned&#xA;   the course pointer 5 degrees CDI would not move as much (or should not because the &#xA;   deviation is really small).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;based on this example CDI needs to know distance from VOR to work properly, yet it works without knowing the distance. How?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If I'm wrong about something, quickly correct me)&lt;/p&gt;&#xA;" OwnerUserId="9938" LastEditorUserId="13197" LastEditDate="2016-04-25T10:26:58.330" LastActivityDate="2016-04-25T10:26:58.330" Title="How does CDI work when flying to VOR without DME?" Tags="&lt;vor&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19271" PostTypeId="1" AcceptedAnswerId="19297" CreationDate="2015-08-24T21:48:20.107" Score="9" ViewCount="34059" Body="&lt;p&gt;I'd like to know how safe the Boeing 737-800 is during takeoff and landing when it's windy. What are the maximum wind speeds for cases of tail, head and cross winds? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've found this resource &lt;a href=&quot;http://www.b737.org.uk/limitations.htm#Wind_Limits&quot; rel=&quot;noreferrer&quot;&gt;http://www.b737.org.uk/limitations.htm#Wind_Limits&lt;/a&gt;, but I'm quite unable to understand the data:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/24nSo.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/24nSo.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the table (which only shows x-wind data), the max wind speed depends on the so called &quot;braking action&quot;, but I don't know what exactly is nor what it depends on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 2&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same resource points out the max tailwind speed, as well as other info: &#xA;&lt;a href=&quot;https://i.stack.imgur.com/xpMz2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xpMz2.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="9745" LastEditDate="2015-08-25T10:06:03.937" LastActivityDate="2021-03-27T23:52:09.897" Title="What is the maximum wind speed a Boeing 737-800 can deal with during takeoff and landing?" Tags="&lt;boeing-737&gt;&lt;wind&gt;&lt;crosswind&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19272" PostTypeId="2" ParentId="19270" CreationDate="2015-08-24T21:49:31.073" Score="4" Body="&lt;p&gt;The VOR and ILS CDI indicates difference, in degrees, between the radial selected and the radial sensed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the plane was far from the VOR and we turn the course pointer 5 degrees, the CDI will move to one side. If the plane was close to the VOR and we turned the course pointer 5 degrees, the CDI would &lt;strong&gt;move exactly as much&lt;/strong&gt;, because it indicates the angular difference in degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is in contrast to a CDI slaved to GPS, which indeed indicates lateral distance from the selected track in miles (en-route; GPS approach has to simulate ILS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOR does nothing with DME. DME is completely independent piece of equipment that was introduced later than VOR. The only relation is that there is a standard correspondence between VOR and DME channels and the DME receiver automatically tunes to the DME frequency corresponding to the VOR or ILS frequency tuned on your VOR/ILS receiver.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-24T21:49:31.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19273" PostTypeId="2" ParentId="19266" CreationDate="2015-08-24T22:02:27.567" Score="3" Body="&lt;p&gt;Another important factor in intercepting a glideslope from above is speed. This is particularly relevant for faster jet aircraft. Jets will typically be able to descend or slow down, but will have a hard time doing both at the same time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the jet needs to intercept the glideslope from above before slowing down enough to extend flaps and landing gear, the spoilers may not provide enough drag to slow down much. If the aircraft does manage to intercept the correct glideslope, the aircraft may be traveling faster than usual while still descending on the glideslope. Going too fast at this point can qualify as an unstable approach, and increases the risk of a late touchdown and a runway overrun due to the excess speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is intercepting from above with flaps and gear extended, and engines at idle, the pilots should take care that when the glideslope is intercepted or a go-around is performed, the aircraft is not pitched up too far before the engines are allowed to develop sufficient power to overcome the high drag of this configuration.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-08-24T22:02:27.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19274" PostTypeId="1" CreationDate="2015-08-24T22:43:37.367" Score="6" ViewCount="552" Body="&lt;p&gt;What would it take to have a new large civil aircraft manufacturer besides Boeing and Airbus, that is not state sponsored (C919, MC-21)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, what are the chances a new company would break into the market? What would it take?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the US past aircrafts, there is an abundance of companies producing large civil aircraft: Boeing, Convair, Douglas, Lockheed, Martin. Then there were the French, the British and the Russian manufacturers. Now there is Boeing and Airbus. Embraer and Bombardier are producing rather small planes for today's standards, even if they are impressive compared to historic planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regional jet market is a lot more competitive, with the CRJs and ERJs under pressure from MRJ, SJ-100 and ARJ. Could one of those companies successfully grow into Boeing and Airbus market?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the chances a start-up, with no state money, will come to market with a new 100+ seats plane in the next 20-30 years? Could a SpaceX type of company be successful in the airplane manufacturing industry?&lt;/p&gt;&#xA;" OwnerUserId="9939" LastEditorUserId="1467" LastEditDate="2015-08-25T06:45:56.140" LastActivityDate="2015-09-04T03:27:13.507" Title="What would it take to have a new large civil aircraft manufacturer?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19275" PostTypeId="2" ParentId="19270" CreationDate="2015-08-24T23:02:56.827" Score="4" Body="&lt;p&gt;The change in &quot;sensitivity&quot; of the CDI needle as you approach a VOR has nothing to do with the DME distance - it depends on your &lt;em&gt;lateral distance&lt;/em&gt; from the VOR.&lt;br&gt;&#xA;You could be 5 miles straight up from the VOR (showing 5 miles on the DME), but the VOR receiver's sensitivity will depend on your lateral distance from the VOR.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is because the VOR is displaying a difference in angular position: how many &lt;em&gt;degrees of arc&lt;/em&gt; you are away from the desired course. The OBS knob on your CDI is selecting a roughly one-degree wide &lt;em&gt;corridor&lt;/em&gt; that you want to be within, which is a pie-shaped wedge around the radial you've selected.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That wedge extends out from the VOR, getting wider as you get further from the station.&lt;br&gt;&#xA;To illustrate, look at the 50-degree wide corridor highlighted in yellow below:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AtJSp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AtJSp.png&quot; alt=&quot;Degres of Arc, with corridor&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has two practical sets of effects on VOR navigation:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The CDI needle sensitivity varies inversely with distance from the station&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Far&lt;/strong&gt; from the VOR station the CDI needle has low sensitivity: A large variation in position (miles) is a small number of degrees of arc away, so you could be a mile off the centerline of your selected course with the needle still nearly centered.  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Close&lt;/strong&gt; to the VOR station the CDI needle is extremely sensitive and &quot;twitchy&quot; - a tenth of a mile left or right could be full-scale deflection, because it represents being several degrees of arc off course.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;VERY Close&lt;/strong&gt; to the VOR station the CDI needle twitches erratically to the point of being nearly unusable because the VOR decoder in your aircraft can't determine which radial you're actually on. (Shortly after this you will usually fly past the station, and eventually the needle will calm down again.)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The OBS knob sensitivity &lt;em&gt;appears&lt;/em&gt; to vary directly with distance from the station&lt;/strong&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/a/19272/64&quot;&gt;As Jan noted&lt;/a&gt; an ideal VOR (transmitter and receiver) would vary the same number of &lt;em&gt;dots of deflection&lt;/em&gt; for the same number of &lt;em&gt;degrees dialed on the OBS&lt;/em&gt;, whether you're 10 miles from the station or 10 feet. With real world hardware though the OBS knob's sensitivity is also affected by distance from the VOR, but in the opposite way from the CDI needle.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Very Close&lt;/strong&gt; to the VOR station the distance between each radial gets small enough that they are practically overlapping, and your radio may wind up decoding the VOR signal as indicating any one of those overlapping radials. Spinning the OBS knob appears to have less of an effect here, particularly with mechanical meter-movement CDIs, because the needle is twitching enough that what you're seeing is an average of what's being decoded. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Far&lt;/strong&gt; from the station - far enough that the VOR receiver can &lt;em&gt;definitively&lt;/em&gt; decode which radial it thinks you're on - the CDI &lt;em&gt;appears&lt;/em&gt; to be more sensitive: The signal is definitely 065 degrees, and when you change the OBS value to 070 the needle will move to reflect the difference between the selected and detected value, with no erroneous decodings to mess it up. At these distances the VOR behaves more-or-less ideally, as Jan described.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-24T23:02:56.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19277" PostTypeId="2" ParentId="19274" CreationDate="2015-08-24T23:52:48.910" Score="2" Body="&lt;p&gt;This question is much more about economics than about aviation. What would it take to have a new large civil aircraft manufacturer? It is a question of economics, and the analysis is essentially indifferent to the industry, per se.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No surprise that the regional market is more competitive, in the sense that there are more aircraft manufacturers. Generally, as aircraft increase in size they become more difficult to produce while the market for them grows smaller. &lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-09-04T03:27:13.507" LastActivityDate="2015-09-04T03:27:13.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19278" PostTypeId="2" ParentId="19248" CreationDate="2015-08-25T00:31:41.597" Score="8" Body="&lt;p&gt;It's not that airports are not standardized -- in the US, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1f13ee6233ac3b576e6087a53e65fea4&amp;amp;mc=true&amp;amp;node=pt14.3.139&amp;amp;rgn=div5&quot;&gt;FAR part 139&lt;/a&gt; describes the standards that your typical significant airport must meet.  It's that they must be tailored to fit the local conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;usage mix (business GA, flight training, cropdusters, heavy jets, military fighters, aircraft factories, and more)&lt;/li&gt;&#xA;&lt;li&gt;topography (runways have the most stringent standards on topography of &lt;em&gt;any&lt;/em&gt; transportation facility found on land, even more stringent than rail lines, and also can't bend around corners)&lt;/li&gt;&#xA;&lt;li&gt;wind direction (especially important if you are in an area with variable weather and/or handling small planes with poor crosswind capability)&lt;/li&gt;&#xA;&lt;li&gt;weather of other sorts (do you need extra long runways due to &quot;hot and high&quot; problems such as Mexico City? Do you need to be able to keep runways clear of extreme snow and ice fall?)&lt;/li&gt;&#xA;&lt;li&gt;operational capacity (multiple primary and even multiple parallel crosswind runways, accompanied by complex taxiway networks, are needed at large airports in order to keep them from becoming total bottlenecks, see SAN or LHR for what happens when you can't put more runways in)&lt;/li&gt;&#xA;&lt;li&gt;obstacle clearance (instrument approaches need significant swathes of clear airspace in straight lines unless you are willing to limit your customers to Part 121, 135, 91K, and business 91 operators with &lt;em&gt;very&lt;/em&gt; recent avionics capable of flying Radius-to-Fix (RF) legs, and these requirements become more and more stringent as the weather gets worse.  Phoenix can get away with having obstacle issues because the weather doesn't exactly turn rotten there very often, but say Chicago O'Hare, Heathrow, or St. John's needs to be able to get planes in even in truly terrible conditions of thick fog, swirling snow, and driving rain)&lt;/li&gt;&#xA;&lt;li&gt;and landside connectivity (major passenger facilities will need gobs of parking and major highway connections, as well as hooks into public transit, while a cargo hub or aircraft factory will need the ability to handle heavy trucks or even shipments by freight rail, and there's also the need for fuel...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As a result, the standards in part 139 and the various documents that implement it must be quite flexible to adapt to the varying needs of the NAS' airports.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-08-25T00:31:41.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19279" PostTypeId="1" AcceptedAnswerId="19311" CreationDate="2015-08-25T01:19:31.243" Score="5" ViewCount="2908" Body="&lt;p&gt;A bigger cockpit window would increase the pilot's vision of a runway. So why can't they be bigger?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;https://aviation.stackexchange.com/questions/16862/what-are-the-factors-behind-increasing-aircraft-window-sizes&quot;&gt;this question&lt;/a&gt; covers cabin window size already, but this question is about cockpit windows specifically.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-07T14:33:23.877" Title="Why don't airliners have bigger cockpit windows?" Tags="&lt;airliner&gt;&lt;cockpit&gt;&lt;windows&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="19280" PostTypeId="1" AcceptedAnswerId="19288" CreationDate="2015-08-25T01:23:31.177" Score="3" ViewCount="8186" Body="&lt;p&gt;I have known that when you climb, you push the throttle to maximum and adjust the vertical speed with the commands (elevator) and the trim. Then when you reach the desired altitude you pull the throttle to cruise RPM setting (2350 for example) and it will maintain level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For descents you pull the throttle to decrease RPM and you adjust your vertical speed with the commands and the trim again. Then when you reach the desired altitude you push the throttle to cruise RPM setting again and it will maintain level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, using the carb heat (hot when lowering down the RPM and cold when increasing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this correct? Is there a better way to perform this maneuvers?&#xA;Thanks, and sorry for the noob question.&lt;/p&gt;&#xA;" OwnerUserId="9941" LastActivityDate="2015-08-25T07:24:15.197" Title="How to perform climbs and descents?" Tags="&lt;maneuver&gt;&lt;climb&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19281" PostTypeId="1" AcceptedAnswerId="19282" CreationDate="2015-08-25T02:05:26.463" Score="7" ViewCount="1984" Body="&lt;p&gt;lets say an airplane needs to get to a certain route but doesnt have the fuel to do and it needs to store in the anti-shock bodies. Is it possible?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="64" LastEditDate="2015-08-25T02:50:22.577" LastActivityDate="2019-08-16T21:04:09.080" Title="Can fuel be stored in the anti-shock bodies?" Tags="&lt;fuel-tanks&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19282" PostTypeId="2" ParentId="19281" CreationDate="2015-08-25T02:49:58.357" Score="7" Body="&lt;p&gt;Fuel is stored in fuel tanks, which typically have two requirements:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;They must be sealed so as to contain the fuel in all probable flight attitudes.&lt;br&gt;&#xA;(Ideally they will keep it contained in a few  &lt;em&gt;improbable&lt;/em&gt; ones too.)&lt;/li&gt;&#xA;&lt;li&gt;They must have appropriate plumbing to get the fuel to the engines.&lt;br&gt;&#xA;(There are some exceptions to this, but &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/January/27/Cirrus-chute-deployment-videotaped-by-Coast-Guard&quot; rel=&quot;noreferrer&quot;&gt;fuel in a tank you can't use is not helpful in flight&lt;/a&gt;.)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Anti-Shock bodies are typically not fuel tanks - they meet neither requirement as they are not watertight (fuel will just pour out of them), and there's no plumbing to get the fuel out of, or for that matter &lt;em&gt;into&lt;/em&gt; them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &quot;Exhibit A&quot;, take a look at the anti-shock bodies around the 787 flap tracks &amp;amp; actuators- Note that the anti-shock body is hollow, but unsealed. Any fuel (or water) in here would simply pour out the trailing edge when the flaps are extended.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/YLtJi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YLtJi.jpg&quot; alt=&quot;Anti-shock bodies for 787 flap track, open with flaps extended&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-25T02:49:58.357" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19283" PostTypeId="2" ParentId="19274" CreationDate="2015-08-25T03:03:50.873" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the chances a start-up, with no state money, will come to market with a new 100+ seats plane in the next 20-30 years?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you count Bombardier, the chances are roughly 100%. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CSeries#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bombardier C-Series&lt;/a&gt;, which will seat 140 (160 max,) is scheduled to enter service within this year (2015.) However, Bombardier is hardly a 'start-up' in the normal sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8SQp1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8SQp1.jpg&quot; alt=&quot;Bombardier C-Series&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Bombardier C-Series Mock-Up (Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Bombardier_CSeries_mockup.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a real start-up (e.g. a SpaceX-style company,) the chances will be much more slim. It takes billions of dollars worth of investments to design a modern commercial airliner before you will ever see the first dime of revenue. Start-ups generally won't have access to that kind of money until they have had time to mature and developed a steady revenue stream from other successful products (which is how Bombardier is doing it.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Could a SpaceX type of company be successful in the airplane manufacturing industry?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That depends greatly on the type of airplanes in question. Undoubtedly, this is possible in the light general aviation market. Several such companies have come and gone over the years. One interesting start-up that is planning to enter production soon is &lt;a href=&quot;https://en.wikipedia.org/wiki/Terrafugia&quot; rel=&quot;nofollow noreferrer&quot;&gt;Terrafugia&lt;/a&gt;, a start-up from MIT, which is building &lt;a href=&quot;https://en.wikipedia.org/wiki/Terrafugia_Transition&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft that fold up into street-legal cars&lt;/a&gt; that can just drive away from the airport and park in your garage. However, the larger airliner market is a completely different ballgame, involving development costs that are orders of magnitude higher. Start-ups have a difficult time getting started in markets with such huge barriers to entry.&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-08-25T03:03:50.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19285" PostTypeId="1" CreationDate="2015-08-25T07:01:14.173" Score="6" ViewCount="204" Body="&lt;p&gt;I have tried to ask this &lt;a href=&quot;http://chat.stackexchange.com/transcript/message/23628550#23628550&quot;&gt;in chat&lt;/a&gt; and I have been invited to ask a full fledged question here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it true that an old (say about between the two world wars) take-off technique, to compensate for the p-factor experienced at high throttle settings, was to put the aircraft misaligned to the runway and let the p-factor align the aircraft to the center-line?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: take an aircraft with a p-factor that makes it yaw to the left, the pilot would have placed the aircraft on the left side of the center-line, with the nose to the right (so, looking at the center-line).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1289" LastEditDate="2015-08-25T09:47:35.657" LastActivityDate="2015-08-25T09:47:35.657" Title="Did old propeller aircraft begin takeoff off-center to counter p-factor?" Tags="&lt;aviation-history&gt;&lt;p-factor&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19286" PostTypeId="2" ParentId="19281" CreationDate="2015-08-25T07:10:29.770" Score="14" Body="&lt;p&gt;Yes, and there have been cases of this. Tip tanks of the period when aircraft flew already supersonic and jet engines were still very thirsty are a good example. Below you see the area-ruled tip tank of the F-5.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NjrmM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NjrmM.jpg&quot; alt=&quot;F-5 tip tank&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-5 tip tank (picture &lt;a href=&quot;http://www.panoramio.com/photo/39560832&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that @voretaq7 got me thinking, I should also mention the &quot;Doppelreiter&quot; fuel tanks (slipper fuel tanks) which were used on some German fighter airplanes in WW II. They were mounted above and behind the wing, and to everyones surprise they had little impact on the top speed of the airplanes, and in case of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_309&quot; rel=&quot;nofollow noreferrer&quot;&gt;Me-309&lt;/a&gt; helped to increase it slightly. They were the first practical application of &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule/7454#7454&quot;&gt;Küchemann carrots&lt;/a&gt; and worked much like the flap track fairings of today's airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qHj9Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qHj9Z.jpg&quot; alt=&quot;FW-190 A with Doppelreiter tanks&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FW-190 A with Doppelreiter tanks.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-25T20:52:06.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19287" PostTypeId="2" ParentId="19285" CreationDate="2015-08-25T07:21:33.470" Score="2" Body="&lt;p&gt;Why ask in past tense? The &lt;a href=&quot;https://en.wikipedia.org/wiki/Akaflieg_M%C3%BCnchen_M%C3%BC23_Saurier&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mü-23 motor glider&lt;/a&gt; has a central wheel and would need someone to hold a wingtip during take-off. Sometimes, a different technique is used: The aircraft is parked at a right angle to the (grass) runway, with the wingtip pointing into the intended take-off direction on the ground. When the pilot opens the throttle, he steps on the rudder, causing the aircraft to swerve into the desired direction and rotating into a horizontal attitude thanks to the centrifugal force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SF7P3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SF7P3.jpg&quot; alt=&quot;Akaflieg München Mü-23&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Akaflieg München Mü-23 (picture &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Akaflieg_Mue_23.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-08-25T07:21:33.470" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19288" PostTypeId="2" ParentId="19280" CreationDate="2015-08-25T07:24:15.197" Score="8" Body="&lt;p&gt;To enter the climb, it's power, attitude, trim. That is, start by setting climb &lt;strong&gt;power&lt;/strong&gt;, as you already know. Remember to compensate for adverse yaw with the rudder. Immediately raise the nose to the climb &lt;strong&gt;attitude&lt;/strong&gt;. Your instructor will teach you to recognise what this looks like in your aircraft: e.g. there might be a part of the dash that lines up with the horizon. Your airspeed will drop away to the desired airspeed for the climb: usually the best-climb speed. Once you're stable and balanced, at the correct airspeed, use the elevator &lt;strong&gt;trim&lt;/strong&gt; to remove the need for pressure on the stick (or yoke).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To level off from the climb, it's attitude, power, trim. Start by lowering the nose to a level &lt;strong&gt;attitude&lt;/strong&gt;. You need to start doing this before you reach the desired height, as it takes a few seconds to level off. Once you're level, the airplane will speed up. When you reach cruise speed, reduce the &lt;strong&gt;power&lt;/strong&gt; to cruise power, and compensate for adverse yaw. Again, once you're stable at the correct speed, &lt;strong&gt;trim&lt;/strong&gt; away any constant pressure on the stick.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A gliding or powered descent is similar. Power, attitude, trim to enter the descent. First set the reduced or idle &lt;strong&gt;power&lt;/strong&gt;, and wait for your airspeed to decay to the correct airspeed for your descent. When you reach this airspeed, lower the nose to the glide &lt;strong&gt;attitude&lt;/strong&gt;. Once the attitude and speed are stable, &lt;strong&gt;trim&lt;/strong&gt; the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To level off from the descent, it's power, attitude, trim again. Anticipate reaching the height you want, just like when climbing. Raise the throttle to cruise &lt;strong&gt;power&lt;/strong&gt;. Adding power will naturally cause a pitch-up tendency in most airplanes, so let the nose come up to the level &lt;strong&gt;attitude&lt;/strong&gt;, and then you'll need forward pressure on the stick to keep it there. Once you're stable and level, &lt;strong&gt;trim&lt;/strong&gt; away that forward pressure.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So for most of these attitude changes, the sequence of events is power, attitude, trim (&lt;strong&gt;PAT&lt;/strong&gt; as a mnemonic). Leaving a climb is different: there it's &lt;strong&gt;APT&lt;/strong&gt;, because lowering the nose first lets the speed increase to the cruising speed before you need to touch the throttle. Whenever you change power, you'll need to use rudder to compensate for adverse yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, you maintain the correct rate of climb or descent by keeping the correct airspeed, not by looking at the vertical speed indicator. Usually you just want the best rate of climb or descent, and you'll already know what airspeed achieves this, so it's easy to just check the airspeed indicator every so often and pitch up if you're too fast, or down if you're too slow. There are circumstances where you need to keep a particular rate of climb or descent, but that's not the norm so it's not what's taught first to student pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Pilots' Operating Handbook for the aircraft you're flying will tell you when carb heat is needed. In general, you should have it &lt;strong&gt;hot&lt;/strong&gt; when you're at idle or low power (i.e. in the descent), and &lt;strong&gt;cold&lt;/strong&gt; the rest of the time.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-08-25T07:24:15.197" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19289" PostTypeId="1" AcceptedAnswerId="19296" CreationDate="2015-08-25T07:33:38.947" Score="23" ViewCount="23175" Body="&lt;p&gt;The Boeing 777 has an optional folding wing mechanism to fit into tighter spaces, but it has never been ordered by airlines, according to &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;. Why is this option so unpopular?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now with the Boeing 777X, Boeing is again offering a smaller, less complex wing folding option. Has this been ordered, and are other airliner models planned to incorporate folding wingtips?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="22726" LastEditDate="2019-02-23T05:28:00.723" LastActivityDate="2019-11-20T15:44:46.027" Title="Why has the folding wing option of the Boeing 777 never been ordered?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;folding-wings&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19290" PostTypeId="2" ParentId="19289" CreationDate="2015-08-25T08:27:39.330" Score="14" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;why cant this apply to all airliners?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h3&gt;It can&lt;/h3&gt;&#xA;&lt;p&gt;It can apply to any new or redesigned airliner. It's probably not something you'd need, want or be economically feasible to retrofit to existing in-service airliners.&lt;/p&gt;&#xA;&lt;h3&gt;Disadvantages&lt;/h3&gt;&#xA;&lt;p&gt;Whether the manufacturer or operators want the associated disadvantages is another matter.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;additional expense,&lt;/li&gt;&#xA;&lt;li&gt;complexity,&lt;/li&gt;&#xA;&lt;li&gt;weight and&lt;/li&gt;&#xA;&lt;li&gt;safety/maintenance burden&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Reliability is critical. A 777X may be unable to vacate a runway if a wingtip fails to fold, and it has to do this in a short time (of the order of 20 seconds).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Should the wingtips not fold up and lock into place correctly after the aircraft lands, it could effectively paralyze an airport by delaying both departures and arrivals&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;- &lt;em&gt;&lt;a href=&quot;https://runwaygirlnetwork.com/2015/06/17/why-flawless-777x-folding-wing-functionality-is-important-to-paxex/&quot; rel=&quot;noreferrer&quot;&gt;Liebherr-Aerospace senior executive Heiko Lütjens&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;h3&gt;It's just the tips&lt;/h3&gt;&#xA;&lt;p&gt;Note that only the tips fold, otherwise there would be many more problems in catering for hydraulic, electrical, structural and fuel systems.&lt;/p&gt;&#xA;&lt;h3&gt;Competition&lt;/h3&gt;&#xA;&lt;p&gt;The 777X has a wingspan of 71m. Only &lt;em&gt;when folded&lt;/em&gt; are it's wings about the same width, 64-65m, as its competitor, the A350-1000.&lt;/p&gt;&#xA;&lt;h3&gt;Airport gate width&lt;/h3&gt;&#xA;&lt;p&gt;Wingspan matters when designing an aircraft to operate into existing terminal gates at the specific airports used by the makers' customers.&lt;/p&gt;&#xA;&lt;p&gt;Boeing wants their 777X to be able to fit where the old 777 and its newer competitors can fit.&lt;/p&gt;&#xA;&lt;pre&gt;&lt;code&gt;Aircraft    Wingspan   Passengers&#xA;747-400     60m        345†&#xA;777-300     61m        299†&#xA;A350-1000   65m        369&#xA;777X        71m        350‡&#xA;A380-800    80m        469†&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;p&gt;† Most of the passenger numbers are from British Airways for 4-class operation. They don't represent anywhere near max capacity but are probably closer to typical?&lt;/p&gt;&#xA;&lt;p&gt;‡ Typical 3-class operation.&lt;/p&gt;&#xA;&lt;p&gt;Airbus had to put serious effort in getting airports to accommodate the A380. I guess Boeing really doesn't want the 777X to be competing with the higher-capacity superheavies for space at the bigger gates.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;if the tech already exists&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The notion of folding wings has been around a long time. Since before &lt;a href=&quot;https://en.wikipedia.org/wiki/Short_Folder&quot; rel=&quot;noreferrer&quot;&gt;1913&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9h5TC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9h5TC.jpg&quot; alt=&quot;Short S.64 with folded wings being hoisted aboard a ship&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/qxZ8t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qxZ8t.jpg&quot; alt=&quot;Dewoitine D.371 with folded wings&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xQwqp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xQwqp.jpg&quot; alt=&quot;Douglas A-1 with folded wings&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;It has mostly been used on small aircraft that operate from facilities where space is severely limited.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Boeing's ideas in this area have been known since at least &lt;a href=&quot;http://www.secretprojects.co.uk/forum/index.php?topic=287.0&quot; rel=&quot;noreferrer&quot;&gt;2006&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3mweQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3mweQ.jpg&quot; alt=&quot;&amp;quot;Beaker&amp;quot; aircraft concept with folding wings&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-11-20T15:44:46.027" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="19291" PostTypeId="1" AcceptedAnswerId="19300" CreationDate="2015-08-25T10:46:18.093" Score="7" ViewCount="3584" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the pressure (in bar) in the fuselage at flight ceiling of large passenger airliners?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is this pressure the reason for the difficulty in having large windows? If so, how can the window size be increased?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9946" LastEditorUserId="1696" LastEditDate="2015-10-07T14:40:00.477" LastActivityDate="2019-11-20T22:42:08.517" Title="What is the pressure in a civil aircraft fuselage at flight ceiling?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19292" PostTypeId="1" CreationDate="2015-08-25T11:00:22.723" Score="7" ViewCount="6586" Body="&lt;p&gt;It is for years that I ask myself as a frequent flyer why there is no Airport using a system, like built-in electrical resistances on Runways to avoid Delays/Cancellations and even closing Airfields during winter? The costs of such a system would be for sure less than closing an Airfield for one day.&lt;/p&gt;&#xA;" OwnerUserId="9947" LastEditorUserId="19" LastEditDate="2016-10-31T12:02:09.430" LastActivityDate="2017-09-08T20:28:02.030" Title="Why don't airport have heated runways to deal with winter conditions?" Tags="&lt;commercial-aviation&gt;&lt;airport&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19293" PostTypeId="2" ParentId="19289" CreationDate="2015-08-25T11:13:13.430" Score="2" Body="&lt;p&gt;The B777x share most of the characteristic of B777. However, &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/faqs/aircraftdesigngroup.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;while B777 is Code E(ICAO)/Group V(FAA)&lt;/a&gt;, due to b777x wingspan, it falls into Code F(ICAO)/Group VI(FAA) catalog.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently only A380 and b748 is in  Code F/Group VI catalog, which the fleet size is limited (317+123), only a few airliners has such planes and not many airport can parking place and other infrastructures for those plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When B777x provides wing folding option, it can feet the code E/Group V parking place. The B777x can be served for most of the airport and reduce the cost.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Wing fold is not new idea.It appears after WWI, when aircraft carrier has been developed, because of the limited hangar size, most of the naval aircraft are designed as wing folded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_E-2_Hawkeye&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-2 Hawkeye&lt;/a&gt; with wings folded:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/kYgDm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kYgDm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-18C&lt;/a&gt; with wings folded:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sIpBx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sIpBx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="1467" LastEditDate="2019-07-06T05:06:14.757" LastActivityDate="2019-07-06T05:06:14.757" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19294" PostTypeId="2" ParentId="19291" CreationDate="2015-08-25T11:13:48.180" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the pressure (bar) in the fuselage at flight ceiling of large&#xA;  passenger airliners?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft are typically pressurised to an equivalent altitude of 1800m (0.815 bar) to 2400m (0.750 bar). Be aware this is absolute and not relative to the atmosphere around the plane.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this pressure the reason for the difficulty of having large&#xA;  windows?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is the most important reason. When stuff is not pressurised you can pull off fairly decent stunts, like the huge mirror on the SOFIA aircraft for instance.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What advancement would be a game changer and allow large windows?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Composite materials are currently the big deal and bringing considerable benefits (See &lt;a href=&quot;https://aviation.stackexchange.com/questions/1992/how-are-virgin-galactics-spaceshiptwos-windows-so-large&quot;&gt;this question&lt;/a&gt;). If you can skip the material change entirely, by using a thing such as transparent composites, then you can make them any size you please.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-08-25T11:13:48.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19295" PostTypeId="1" AcceptedAnswerId="19301" CreationDate="2015-08-25T11:38:20.353" Score="21" ViewCount="5126" Body="&lt;p&gt;My understanding is that aircraft use GPS systems for navigation (maybe not the only way to navigate). I would like to understand what would happen if the GPS system fails.  Are there any other navigation systems to fall back on? What would happen if all of them fail? Could all the navigation systems fail?&lt;/p&gt;&#xA;" OwnerUserId="9948" LastEditorUserId="62" LastEditDate="2015-08-25T16:02:23.390" LastActivityDate="2020-07-29T17:01:14.883" Title="What will happen if satellite navigation fails?" Tags="&lt;navigation&gt;&lt;gnss&gt;" AnswerCount="6" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19296" PostTypeId="2" ParentId="19289" CreationDate="2015-08-25T11:50:45.633" Score="28" Body="&lt;p&gt;The folding wingtips are found mostly in naval aviation. The reason is the space constraint inside the hangar of the aircraft carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JjmEd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JjmEd.jpg&quot; alt=&quot;USS Ronald Reagan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:US_Navy_070128-N-9712C-003_Aircraft_fill_the_hanger_bays_on_board_USS_Ronald_Reagan_(CVN_76)_after_recently_embarking_Carrier_Air_Wing_One_Four_(CVW-_14).jpg#/media/File:US_Navy_070128-N-9712C-003_Aircraft_fill_the_hanger_bays_on_board_USS_Ronald_Reagan_(CVN_76)_after_recently_embarking_Carrier_Air_Wing_One_Four_(CVW-_14).jpg&quot; rel=&quot;noreferrer&quot;&gt;US Navy 070128-N-9712C-003 Aircraft fill the hanger bays on board USS Ronald Reagan (CVN 76) after recently embarking Carrier Air Wing One Four (CVW- 14)&lt;/a&gt;&quot; by U.S. Navy Photo by Mass Communication Specialist 2nd Class John P. Curtis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen from the photo, folding the wings offers the only practical way of fitting fighter aircraft inside the cramped hangar space. For example, the F/A-18C/D had a wing span of 11.43m; this was reduced to 8.38m with the wings folded, a 26% reduction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the price to pay is an increase in complexity, weight, price and increased maintenance. The figure shows the wing folding mechanism of a F 18.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UVnHt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UVnHt.jpg&quot; alt=&quot;F 18 Wing fold&quot;&gt;&lt;/a&gt;&#xA;Source:polepositionimagery.com.au&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major drawbacks of folding wings are,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The increased weight and complexity due to the folding mechanism. The folding mechanism takes time to operate and there are safety concerns if they get stuck in a position.&lt;/li&gt;&#xA;&lt;li&gt;The folding of wings limits the fuel capacity and as a result, the range of the aircraft, as fuel is usually not carried on the folding part of the wings.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HPbCb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HPbCb.jpg&quot; alt=&quot;F-18 Overview&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: zarco-macross.wikidot.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen, the F/A doesn't carry fuel in the folding part of the wing. In fact, after the airlines didn't take up its folding concept in 777, Boeing added fuel tanks to that area and increased range of the 777-200/300. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has previously been no reason for airliners to fold their wings, as airports offered enough space for operations and ground movement. However, as the size of aircraft and their aspect ratios grow (to reduce drag), designers are finding it more and more difficult to keep the wingspan below the 80m 'box' which airlines believe is the maximum they can cope up economically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first major program to be affected by this limitation was the A380, which limited the wingspan of the aircraft to less than 80m and reduced its aspect ratio.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rrOS6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rrOS6.png&quot; alt=&quot;Comparison of aircraft&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Giant_planes_comparison.svg#/media/File:Giant_planes_comparison.svg&quot; rel=&quot;noreferrer&quot;&gt;Giant planes comparison&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Ctillier&quot; rel=&quot;noreferrer&quot; title=&quot;User:Ctillier&quot;&gt;Clem Tillier&lt;/a&gt; (clem AT tillier.net) - Original Work. Licensed under CC BY-SA 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, Boeing is facing the same problem. The proposed 777x is the largest-wingspan aircraft Boeing has ever produced. However, in the case of the A380, Airbus managed to reduce induced drag through the use of wingtip fences, among other design decisions. The 777x is expected to have a raked wingtip, which is not as space effective as the wingtip fence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8caQq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8caQq.jpg&quot; alt=&quot;777x Wingspan&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Flightglobal.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, Boeing is considering folding wingtips. However, there are important differences between the original plan in 777 and the proposed plan in 777x.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the original plan, Boeing proposed to fold 21' of the wingtip. However,the new plans call for folding only 10'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tA6js.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tA6js.gif&quot; alt=&quot;777 Wing Folding&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Original Wing folding plan in Boeing 777. Source:www.seattletimes.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lVbLg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lVbLg.jpg&quot; alt=&quot;777x folding tips.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image:Boeing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen from the figure, the folding plan is much more modest. This is not expected to have the drawbacks associated with the the original plan, as,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The end of the wing will not house controls.&lt;/li&gt;&#xA;&lt;li&gt;As the size of the wing to be folded is smaller, the folding mechanism will not be as heavy and complicated.&lt;/li&gt;&#xA;&lt;li&gt;That part probably will not carry fuel.&lt;/li&gt;&#xA;&lt;li&gt;Advances in actuation systems since the original 777 will reduce the weight penalty.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To put things into perspective, the 747-400's winglets were 6' feet tall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines have already placed orders for 777x and it is their operational record that will determine if other aviation manufacturers (Airbus, that is.) will follow suit.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-02-23T05:31:50.470" LastActivityDate="2019-02-23T05:31:50.470" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19297" PostTypeId="2" ParentId="19271" CreationDate="2015-08-25T11:59:22.333" Score="13" Body="&lt;p&gt;As your source shows, the maximum tail wind is fixed and fairly simple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting slightly more complex, there is technically no maximum headwind I'm aware of, although most airports will close when the wind gets much above 50 knots, and even with the wind coming almost straight down the runway, you still get some crosswind component, which factors in. Expect to see many pilots divert in winds much above 40 knots even if the airport is open, especially if gusting to above 50.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crosswinds are a little different as they depend on the braking action - basically how grippy the runway is. Simplified, you can think of it as a scale from dry weather, through slightly and very wet, then slush and ice. The grippier the runway, the more the tyres will grip and the higher crosswind the aircraft can deal with. The higher numbers in the chart you show are for a dry runway (good on your chart) the lower numbers for wet or icy (poor on your chart) runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although it's written in terms of 'braking action', it's really a measure of grippiness, and it's important both when braking, but also for the ability of the tyres to prevent the aircraft sliding laterally off the runway. This job doesn't solely come down to the tyres, but they're part of it. This is also a large part of the reason why landings and takeoff have different maximum crosswinds on some aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-08-25T14:50:08.017" LastActivityDate="2015-08-25T14:50:08.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19298" PostTypeId="2" ParentId="19295" CreationDate="2015-08-25T12:25:04.090" Score="0" Body="&lt;p&gt;There's a bunch of alternatives for the case that GPS fails. I guess that they would first resort to VOR-navigation ( &lt;a href=&quot;http://www.pyrochta.ch/flash/start_vor.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.pyrochta.ch/flash/start_vor.htm&lt;/a&gt; ). And if all else fails you'd still have a compass, a map and a clock for timing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I think that, if all communication failed as well, at some point some fighters would guide you to the next airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will be never in a situation where you don't know anymore where you are and where you're going.&lt;/p&gt;&#xA;" OwnerUserId="3916" LastActivityDate="2015-08-25T12:25:04.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19299" PostTypeId="2" ParentId="19295" CreationDate="2015-08-25T12:27:36.280" Score="6" Body="&lt;p&gt;The probability of the entire GPS system to fail is quite low. Individual satellites may fail, however that can be detected by the GPS receiver itself. Usually there are more satellites in view than minimally needed so the faulty satellite will be excluded from the position calculations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If no GPS position can be calculated, for example because of a failure of the GPS receiver, the aircraft has a number of alternative navigation systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In no case GPS will be used as the sole means of navigation. There are always other navigation systems used in parallel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are equipped with VOR receivers, which uses signals from ground based navigation beacons to determine their direction. These VOR stations have a range of up to 200 NM. This isn't of much use of the oceans of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inertial Navigation Systems calculate the position by keeping track of all accelerations and rotations of the aircraft. The accuracy degrades over time but it is good enough to find your way over the oceans. The good thing about INS is that it is totally independent of external systems. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-08-25T12:27:36.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19300" PostTypeId="2" ParentId="19291" CreationDate="2015-08-25T12:37:54.230" Score="8" Body="&lt;p&gt;The pressure inside the cabin is usually more than the outside pressure at the cruise altitude. The pressure altitude (ISA altitude with the same pressure) inside the cabin of civil aircraft is called the equivalent effective cabin altitude or normally cabin altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft climbs, the cabin altitude is gradually raised so that it reaches around 8000 ft for the aircraft cruising altitude of ~40000 ft. This level is maintained at flight ceiling too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nYf8E.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nYf8E.jpg&quot; alt=&quot;A320 Pressurization Diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.flyertalk.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure is around 0.75 bar inside the cabin. The outside pressure at this point is around 0.2 bar, resulting in a pressure differential of 0.56 bar. This pressure differential causes stresses on the aircraft body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TIeeu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TIeeu.jpg&quot; alt=&quot;Pressure on Aircraft Fuselage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:ecnmag.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the stresses, pressurization - de-pressurizatoin cycle can cause fatigue in the windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As reducing the cabin altitude will improve the passenger comfort, newer aircraft tend to have lower cabin altitudes. For example, the Boeing 787 has a pressure altitude of around 6000 ft and the Bombardier Global Express jet has a cabin altitude of around 4500 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is achieved by the use of advanced composite materials, which allow a higher pressure differential have excellent fatigue properties compared to the metals. As a result, the windows of newer aircrafts are considerably larger than their predecessors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZD6Y1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZD6Y1.jpg&quot; alt=&quot;A380 787 window comparision&quot;&gt;&lt;/a&gt;&#xA;Image: Boeing&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-25T12:37:54.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19301" PostTypeId="2" ParentId="19295" CreationDate="2015-08-25T12:55:43.217" Score="30" Body="&lt;p&gt;It only takes 3 satellites for a GPS fix (4 if you want altitude). There are &lt;a href=&quot;https://www.gps.gov/systems/gps/space/&quot; rel=&quot;nofollow noreferrer&quot;&gt;31 operational satellites&lt;/a&gt; currently in orbit and at any given time you can most likely receive a signal from half a dozen of them at least. That being said the chances of them failing completely is almost 0%. But of course what if they did, well...&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FKupv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FKupv.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;There is always the Russian version of GPS known as &lt;a href=&quot;https://en.wikipedia.org/wiki/GLONASS&quot; rel=&quot;nofollow noreferrer&quot;&gt;GLONASS&lt;/a&gt; so there is effectually an entire redundant global navigation system in space. While not all aircraft are equipped with GLONASS receivers it is of course becoming more common. Even the &lt;a href=&quot;http://gps.dualav.com/explore-by-product/xgps160/&quot; rel=&quot;nofollow noreferrer&quot;&gt;little tiny receiver&lt;/a&gt; I use for GA flights has it now. So there is that redundancy.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s4Lmo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s4Lmo.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In controlled airspace you have ATC there to help you. They can effectively watch you on radar and tell you what to do which is basically what &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying IFR&lt;/a&gt; is. For this you will need an operational altitude encoding transmitter so that ATC knows your altitude along with position. If you are flying VFR and require assistance you could call for Flight Following here in the US, load permitting. They can offer limited guidance but if you tell them you are lost they will generally help.&lt;/p&gt;&#xA;&lt;p&gt;If there is no ATC you can hone in on &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR stations&lt;/a&gt;, or some of the older &lt;a href=&quot;https://en.wikipedia.org/wiki/Radio_direction_finder#Automatic_direction_finder_.28ADF.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;radio direction finders&lt;/a&gt; like ADF systems assuming your aircraft is equipped with such equipment. Some modern handheld radios can also hone in on VOR stations&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lW26s.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lW26s.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;If all that fails you have your good old magnetic compass and hopefully some way of keeping time. With close track of your airspeed, a clock, and a compass you can navigate pretty accurately even in the blind (although I don't recommend that).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YRHW9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YRHW9.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;No compass, no problem, you always have your ground reference points to get where you need to be. Basic VFR navigation which every pilot know how to do is learned this way. This will require you have a VFR map of the area which most GA planes will carry. Note the roads, power lines and other large things marked on the map that are easily identified from the sky.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RQaK7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RQaK7.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Outdated/less popular systems:&lt;/strong&gt;&#xA;Inertial navigation systems are still used in plenty of places however they are not as accurate as other systems available in modern aircraft but they work by knowing how fast you have gone and in what direction you have accelerated to that speed. Thus position can be calculated. INS systems suffer from &lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;integration drift&lt;/a&gt; which can add up over time and make the margin of error pretty big.&lt;/p&gt;&#xA;&lt;p&gt;There was once a time in history when you could get a navigators rating on your license. These people were trained in many times of navigation including celestial navigation. Older planes were even outfitted with a sextant for that very reason.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ygdu9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ygdu9.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Loran-C&quot; rel=&quot;nofollow noreferrer&quot;&gt;LORAN C&lt;/a&gt; was officially shut down here in the US/Canada in 2010 but there are still active chains elsewhere in the world. Some planes out there still have the units in them (one of the Cherokees I fly still has it sitting there). So depending on where you are you may be able to use it.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;What Time Is It:&lt;/strong&gt;&#xA;The US GPS network is synced up via the &lt;a href=&quot;https://en.wikipedia.org/wiki/United_States_Naval_Observatory&quot; rel=&quot;nofollow noreferrer&quot;&gt;USNO master clock&lt;/a&gt; and while it is unlikely that all the satellites will fail simultaneously or fall out of the sky, or be shut down. The master clock does provide a central point of failure for the system. While I am not up to date on the full function of the system I would imagine that a downed clock could introduce a margin of error into the system. Worse so an incorrect value fed from the master system may cause an erroneous reading.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="14661" LastEditDate="2020-07-29T17:01:14.883" LastActivityDate="2020-07-29T17:01:14.883" CommentCount="18" ContentLicense="CC BY-SA 4.0" />
  <row Id="19302" PostTypeId="2" ParentId="19292" CreationDate="2015-08-25T13:11:12.270" Score="13" Body="&lt;p&gt;Removing snow from runways is not the biggest problem. Snow can be ploughed from the runways pretty quickly. The problems occur:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When it is snowing, especially in snow storms with strong winds and poor visibility. The wind and visibility are bigger problem than the snow laying on the runway and when the snow fall rate is such that the snow becomes a problem itself, the heating system would not be able to keep up melting it anyway.&lt;/li&gt;&#xA;&lt;li&gt;Due to snow and ice accumulating on aircraft preparing for take-off. Obviously heating runways would not help in this regard.&lt;/li&gt;&#xA;&lt;li&gt;Due to fog, which is much more common in winter. Again, heating runways would not help in this regard.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So runway heating would probably not help very often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the runway has to be extremely strong, because aircraft have much higher weight on each tire than cars. A heating system with adequate durability would therefore be really expensive.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-08-25T13:11:12.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19303" PostTypeId="2" ParentId="19292" CreationDate="2015-08-25T13:12:22.177" Score="8" Body="&lt;p&gt;I don't know how to calculate it, but I am sure that heating a runway will use a lot of electricity. Imagine yourself on that runway with a 2Kw electric fire in snowy conditions. You would still be freezing, and the fire would have no effect on the runway surface. Even if you could do this, the heating might create fog above the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think runway conditions are the biggest problem in winter, because as long as it isn't snowing continuously, snow ploughs can clear a runway (salt isn't used because it would be damaging/corrosive to aircraft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problems in winter often are the other weather conditions such as strong crosswinds, poor visibility, low cloud base, because unless AutoLand is being used (available only on some aircraft/some airports), the pilot generally has to be able to see the runway when coming into land from an height typically of 200 feet.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-25T13:12:22.177" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19304" PostTypeId="1" AcceptedAnswerId="20887" CreationDate="2015-08-25T13:27:57.213" Score="30" ViewCount="6137" Body="&lt;p&gt;The image is extracted from this Airbus A350 &lt;a href=&quot;https://www.youtube.com/watch?v=0gzxgA3zogw&amp;amp;t=219&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; (at 3m40s, when taking off)&lt;a href=&quot;https://i.stack.imgur.com/nZWzs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nZWzs.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;I circled in purple the strange pattern formed by few black straight lines. I'm quite puzzled as I have no idea of what it is or what purpose it can serve.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: I would like to sum up the ideas in comments as there is interesting guess and discussions in the comments. It is a strange &lt;em&gt;device&lt;/em&gt; which can be:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a kind of gauge useful as the windscreen seems to be a completely new one and the aircraft presented is one of the test aircraft&lt;/li&gt;&#xA;&lt;li&gt;part of some windscreen heating device&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2021-04-21T16:31:19.320" LastActivityDate="2021-04-21T16:31:19.320" Title="What is this pattern on the windshield of aircraft?" Tags="&lt;feature-identification&gt;&lt;windscreen&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="19305" PostTypeId="2" ParentId="19254" CreationDate="2015-08-25T14:07:21.153" Score="8" Body="&lt;p&gt;From a general aviation standpoint here in the US, yes. Engine out landings and general procedures are practiced during your PPL training. No particular failure is trained for because there are really only 2 situations, the engine is running or the engine is not running. The procedures for different planes vary but generally you set for best glide, pick a touchdown point (airstrip if you can) and head for it. Once in route you can attempt a restart if you can identify the problem and solve it. on some planes you can feather the propellor and such. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said that generally applies to single engine planes, in a twin engine plane there are a few more situations depending on the design of the plane. In a twin you may have a &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Critical_engine&quot; rel=&quot;noreferrer&quot;&gt;critical engine&lt;/a&gt;&quot; as such engine outs are practiced with that in mind and the procedures are adjusted appropriately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the why... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lots of things that can take out an engine like a bird strike, a mechanical failure, a fire etc. The fact of the matter is that it &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;does happen&lt;/a&gt;  all be it not that often, you would be a fool not to prepare. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdote: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I started my training I got curious about piston engines cutting out so I began to ask around. Youtube videos aside, I was only able to actually find one guy who knew a guy that once lost an engine. Engine manufacturing has come a long way since the advent of airplanes and engines are simply more reliable than they once were. Here is a great article that touches on some of the &lt;a href=&quot;http://www.flyingmag.com/what-happened-piston-twin&quot; rel=&quot;noreferrer&quot;&gt;twin engine points&lt;/a&gt; about reliability. While it does happen and you should never assume &quot;this wont happen to me&quot; engines are much better than they were 50 years ago when some of the requirements were made for the tests and training standards. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-08-25T14:07:21.153" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19306" PostTypeId="1" CreationDate="2015-08-25T14:13:19.057" Score="0" ViewCount="6318" Body="&lt;p&gt;Recently someone on another thread recommended the following video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=we4G_X91e5w&quot; rel=&quot;nofollow&quot;&gt;Andrew Godwin - What can programmers learn from pilots? - PyCon 2015&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where the speaker, at about ~3:14, talking about pilots mentions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;not to the point where we can replace them with computers, because we're not there yet&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;which got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How close are we to replacing pilots with computers? (like totally)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5642" LastActivityDate="2015-08-25T16:29:40.223" Title="How close are we to replacing pilots with computers?" Tags="&lt;pilots&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2015-08-25T16:00:38.683" ContentLicense="CC BY-SA 3.0" />
  <row Id="19307" PostTypeId="2" ParentId="19306" CreationDate="2015-08-25T14:31:37.273" Score="1" Body="&lt;p&gt;This is a complex question and one that involves both a technical aspect as well as a legal aspect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From one standpoint there is nothing stopping the FAA from requiring that a human pilot remain in the plane should anything go wrong (or simply to create jobs). Lobbying power should not be underestimated here, there are lots of pilots (and a union behind them) that would be out of work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But lets talk machine take over for a minute. In some regards &lt;strong&gt;&lt;em&gt;parts&lt;/em&gt;&lt;/strong&gt; of the systems do exist. Obviously autopilot to an &lt;strong&gt;&lt;em&gt;extent&lt;/em&gt;&lt;/strong&gt; can fly a plane but this generally involves some human interaction and generally holds speed/altitude/heading a change in any one of those may require physical control changes. In a similar vain &lt;a href=&quot;https://en.wikipedia.org/wiki/Autoland&quot; rel=&quot;nofollow&quot;&gt;auto-land&lt;/a&gt; systems do exist and they do work. HOWEVER they are complex to set up and require human interaction to currently be used. As far as I know there is no automated system that can currently control takeoff (i could be wrong about that though). Do we possess the pieces to assemble a self flying plane, possibly... To do so, and to get it FAA certified is a very big topic.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other issue that arises is updating the whole ATC system. If you have not been following the news this is already a mess. But lets say you had a plane that had no one flying it. If ATC needed to reroute the plane, or issue a change in course it would need a system to do so. Currently that is handled via a radio and person to person communication. You would need to dispatch some kind of command to the plane via a data link to do it in an automated system. Then again you can automate ATC etc. etc. (lets not go down that road.        &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-08-25T14:31:37.273" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19308" PostTypeId="2" ParentId="19306" CreationDate="2015-08-25T14:32:09.907" Score="5" Body="&lt;p&gt;As a person that &quot;tries to replace pilots with computers&quot; I personally say: not even close.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The processing power (certified for flight, not the latest pentium sitting under your desk) is too behind, in particular concerning the point here below.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Synthetic vision is still extremely lacking. This is currently the biggest hurdle to overcome. While pilots can look out of the windows and assess the situation (with some limits, admittedly), computers still have several problems with it, starting from a general lack of cameras and going all the way to the daunting level of processing power required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ability to adapt is still a long way to come. Computers are &quot;fundamentally stupid&quot;, they do what they are told (programmed) to do, they are not capable of adapting to an unforeseen (and never experienced before) emergency. There are several people working in machine learning and the field has advanced significantly in the latest years, but good luck &lt;a href=&quot;https://aviation.stackexchange.com/a/3411/1467&quot;&gt;certifying&lt;/a&gt; those programs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-25T16:29:40.223" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19310" PostTypeId="2" ParentId="19306" CreationDate="2015-08-25T15:24:48.093" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;How close are we to replacing pilots with computers?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In some ways, this has already happened in some limited areas.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flight Engineers and Navigators&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As a precursor to replacing pilots, we have already replaced non-pilot crew on the flight deck. The flight engineer role has been replaced largely by computerized engine systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A significant problem for the remaining pilots can be maintaining their skills during their time in the cockpit when they spend long hours mostly monitoring systems rather than doing hands-on piloting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect, a lot of what commercial and military pilots do boils down to issuing commands to computers, rather than manually (if indirectly) moving control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Bomber pilots&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In the first gulf war, 297 missions were flown by autonomous aircraft. Many explosive payloads were delivered to targets by small aircraft that flew hundreds of km. These navigated and flew without any on-board or remote human pilot controlling them. Cruise missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The alternative would presumably have been greater numbers of human pilots in conventional bombers dropping smart bombs over the target.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Ground attack pilots&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some jobs that would have been carried out by a pilot inside a ground-attack aircraft are now carried out by a UCAV with a remote pilot. These UCAVs have increasing amounts of autonomy. Some are intended to have full autonomy. It isn't hard to envisage a not too distant scenario where the main human interaction with the aircraft is not piloting it, but authorizing firing of weapons.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Helicopter pilots&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Jobs like power-line inspection are, in some remote areas, mostly carried out from helicopters with human pilots but we seem to be on the brink of replacing some of those pilots with drones. That seems a few technically short steps from using autonomous drones. The main time-consuming barrier is probably regulatory change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, to operate a drone for this purpose, you don't need to be a licensed pilot. Is such a drone operator a pilot. Have they replaced one?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;(like totally)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As others have answered, nowhere near.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-25T15:46:17.967" LastActivityDate="2015-08-25T15:46:17.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19311" PostTypeId="2" ParentId="19279" CreationDate="2015-08-25T15:43:10.500" Score="13" Body="&lt;p&gt;The reason is that bigger windows really aren't necessary. They are plenty big for the crew to see the runway just fine. Pilots have more than 180 degrees of visibility, and plenty of vertical visibility as well. Traffic routes and patterns are designed to make it easy for the pilots to see the runway as well. If the runway is behind you, then you need to turn around. If it's below what you can see out the window, you are too high anyway. And if it's above what you can see out the window, you probably have more important issues than finding the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger windows can help spot danger like other aircraft, but airliners are almost always flown under Instrument Flight Rules (IFR) where ATC is responsible for keeping them clear of conflicting traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the past, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot; rel=&quot;noreferrer&quot;&gt;some airliners&lt;/a&gt; did have larger window area. This was more important in an era where instrument navigation was more limited, and the pilots relied much more on their view outside. It was also more common on aircraft with military heritage, where it was more likely for pilots to find themselves relying on visual references instead of navigational aids.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, modern navigation systems have made larger windows even less useful. The instruments can tell pilots just about anything they need to know about anything they can't see out the windows. The 737 actually started with &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737#Flight_systems&quot; rel=&quot;noreferrer&quot;&gt;eyebrow windows&lt;/a&gt;&quot; above the main row of windows. Modern systems have made those less useful, and the extra holes in the fuselage can cause cracks over time. Most 737's delivered today don't have them, and some of the old planes even get those windows plugged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from the functional reasons for not increasing window size, &lt;a href=&quot;https://aviation.stackexchange.com/questions/16862/what-are-the-factors-behind-increasing-aircraft-window-sizes&quot;&gt;the same structural concerns of cabin windows&lt;/a&gt; will apply here as well.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-08-25T15:43:10.500" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19312" PostTypeId="1" CreationDate="2015-08-25T15:43:15.177" Score="1" ViewCount="675" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Top DGCA officials say they do not recall any other instance of this kind where a plane tried to land unsuccessfully six times and then finally touched down in the seventh attempt — whether in India or abroad. (&lt;a href=&quot;http://timesofindia.indiatimes.com/india/DGCA-suspends-two-Jet-pilots-who-landed-in-seventh-attempt-with-fuel-running-dangerously-low/articleshow/48579284.cms&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A better written &lt;a href=&quot;http://avherald.com/h?article=48b217ed&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;report&lt;/a&gt; of the incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming to the question, what has been the maximum number of failed landing attempts for any fully loaded commercial airliner?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-08-25T23:19:48.730" Title="What has been the maximum number of failed landing attempts for any commercial flight yet?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;landing&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19313" PostTypeId="1" AcceptedAnswerId="19315" CreationDate="2015-08-25T15:49:28.697" Score="19" ViewCount="3417" Body="&lt;p&gt;This is actually a tricky question, because it's not just about gross weight, but about how much weight each individual tire imparts into the ground.  This, of course, depends on the design of the suspension and the number of wheels.  Thus a really big craft, with a well designed undercarriage, can land on grass just fine (like a &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=7&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CDUQtwIwBmoVChMI57_K08nExwIVgl6SCh0FnQfk&amp;amp;url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DK85RYSGF1CQ&amp;amp;ei=Qo3cVeeWGYK9yQSFup6gDg&amp;amp;usg=AFQjCNFQDAPfrJmSuc5rOXwAl1LoCtabFA&amp;amp;sig2=_tGF3-uxUIYmIXGi8umZvg&quot;&gt;C-130&lt;/a&gt; for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point being, &quot;how heavy is too heavy&quot; has more to do with specific weight supported by each wheel during landing, and less to do with total landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, kind of a two parter.  Firstly, how much weight can a grass field generally support when an aircraft is landing?  Secondly, how do aircraft designers make landing gear that can land on a grass field without plowing into the ground and ripping off?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="62" LastEditDate="2015-08-25T21:07:54.267" LastActivityDate="2021-04-30T19:34:42.140" Title="How heavy is too heavy to land on a grass strip?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;runways&gt;&lt;grass-field&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19314" PostTypeId="2" ParentId="19295" CreationDate="2015-08-25T16:08:38.483" Score="4" Body="&lt;p&gt;If your GPS receiver (or the entire GPS system) fails, what you have left depends on what you have to begin with. Many GA aircraft that have been upgraded with a GPS receiver (and quite a few that came stock will full glass) still also have a good old navigation radio stack with at least one Omni Bearing Indicator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5m8p2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5m8p2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This indicator works with a radionavigation system called VOR (VHF Omnidirectional Range). Ground stations at known locations broadcast a two-part signal; an omnidirectional radio beacon that identifies the station, and a sweeping, phase-shifting transmission of the same modulated signal that the nav radio compares with the omni signal. The amount of phase difference between the omni and sweeping signal is the same as the compass direction or radial from the station to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots can use this system to fly &quot;Victor routes&quot; between major cities by selecting the VOR radio station they want to fly toward or away from, then dialing in the desired radial they want to approach along (which may be important to avoid obstacles or restricted/controlled airspace), then flying diagonally to that course to intercept the radial before turning toward or away from the station As they approach or pass one station, they can tune in to the next VOR station and radial indicated on the chart. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using two radios, they can also triangulate their location based on the readings from two VOR stations; fly along one radial until you intercept another radial of a different station, and now you know you're at the intersection of those two radials on the map.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOR (and other radionavigation methods like the military equivalent TACAN) are not quite as accurate as GPS, nor quite as reliable in all scenarios (many of these systems require line of sight which is more difficult in mountainous terrain or at very low altitude) but it's been the system that U.S. civil aviation has depended on since the 1960s, and if you know how to use it properly it works quite well.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-25T16:35:55.367" LastActivityDate="2015-08-25T16:35:55.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19315" PostTypeId="2" ParentId="19313" CreationDate="2015-08-25T16:58:20.323" Score="22" Body="&lt;p&gt;Your second question is really easy to answer:&lt;br&gt;&#xA;&lt;strong&gt;Q:&lt;/strong&gt; &lt;em&gt;How do aircraft designers make landing gear that can land on a grass field without plowing into the ground and ripping off?&lt;/em&gt;&lt;br&gt;&#xA;&lt;strong&gt;A:&lt;/strong&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Tundra_tire&quot; rel=&quot;noreferrer&quot;&gt;Big Fat Low-Pressure Tires.&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EEyXd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EEyXdm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;a href=&quot;https://i.stack.imgur.com/Exggh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Exgghm.jpg&quot; alt=&quot;Tundra Tire size comparison (8.5 inch vs 6 inch)&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;A wide, low-pressure tire has a larger contact patch with the ground, spreading the aircraft's weight over that larger area helps prevent the tire from digging into the ground, and lets the aircraft roll more easily on rough or soft surfaces.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Your first question - &lt;em&gt;How much weight can a grass strip support?&lt;/em&gt; is a much tougher one.  The bearing strength of an unimproved surface depends on a number of factors (some big ones: The composition of the runway bed, its drainage, and what kind of surface cover - turf, rocks, etc. - it has).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at aerial photos of &lt;a href=&quot;https://en.wikipedia.org/wiki/Edwards_Air_Force_Base&quot; rel=&quot;noreferrer&quot;&gt;Edwards Air Force Base&lt;/a&gt; you'll notice part of the runway complex includes a dry lake bed:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4Xm80.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4Xm80.jpg&quot; alt=&quot;Edwards AFB with part of Lake Rogers visible&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Some pretty heavy stuff has taken off from and landed on those runways - &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_sites#Edwards_Air_Force_Base&quot; rel=&quot;noreferrer&quot;&gt;space shuttles have landed there&lt;/a&gt;.&lt;br&gt;&#xA;Similarly &lt;a href=&quot;https://en.wikipedia.org/wiki/TACA_Flight_110#Investigation_and_recommendations&quot; rel=&quot;noreferrer&quot;&gt;TACA Airlines Flight 110&lt;/a&gt;, a Boeing 737, landed on a levee at NASA's Michoud Assembly Facility (and was subsequently repaired and took off again, though they used an access road for the takeoff rather than the grass levee). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely if you tried to land a Cub on a grass strip that's saturated with water after a rainy month there's a chance your tires might sink into the mud.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.team-eagle.ca/wp-content/uploads/2012/10/CBR_Tech_Presentation_SWIFT_2012.pdf&quot; rel=&quot;noreferrer&quot;&gt;CBR Technologies has a nice presentation on unpaved runways&lt;/a&gt;, which includes some discussion of how their bearing strength (and thus maximum landing weights, tire pressure limits, etc.) can be calculated, but each unimproved runway will be different, and the values will likely change over time.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-25T16:58:20.323" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19316" PostTypeId="1" AcceptedAnswerId="19321" CreationDate="2015-08-25T17:54:48.700" Score="6" ViewCount="653" Body="&lt;p&gt;Is there a public and current (AIRAC-cycle 1509)  &lt;strong&gt;list&lt;/strong&gt; of all worldwide victor- and jetairways (including the pertaining intersections)? I'm not searching for a graphical map of the airways, but more for a text file listing all items.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sorry for the poor tagging, I couldn't find any suitable tag (there isn't one for &quot;airway&quot; or &quot;intersections&quot;).&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="9945" LastEditorUserId="22726" LastEditDate="2020-06-03T21:27:34.050" LastActivityDate="2020-06-03T21:27:34.050" Title="Is there a list of all airways?" Tags="&lt;navigation&gt;&lt;aeronautical-charts&gt;&lt;flight-path&gt;&lt;airways&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19319" PostTypeId="2" ParentId="17440" CreationDate="2015-08-25T20:15:05.050" Score="7" Body="&lt;p&gt;The B-2's pitot plate has actually been &lt;a href=&quot;https://sma.nasa.gov/docs/default-source/safety-messages/safetymessage-2009-01-01-usafb2mishap.pdf?sfvrsn=4&quot; rel=&quot;nofollow noreferrer&quot;&gt;the cause of an accident&lt;/a&gt; in conditions that may or may not have had the same effect on aircraft with pitot tubes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitot plates work much like pitot tubes; they measure the pressure of incoming air. The main difference is just how they measure it: pitot tubes measure the ram force of air while pitot plates measuring how much air is constricted by an obstruction. Pitot plates direct air through a &quot;plate&quot; with a hole that impedes the flow almost like how a Venturi tube accelerates fluids. Pictured: Pitot/Orifice plate&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gEiq5.gif&quot; alt=&quot;Orifice Plate&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitot tubes are easier to maintain, inspect, and install. Some of their main problems that you might not encounter with a pitot plate, such as icing, are countered with tested and approved safety systems (like heating). In addition, pitot tubes are not the only instrument to measure airspeed; most commercial and GA aircraft use pitot-static systems in which other pressure sensors are used to get a better and more reliable reading. Pitot plates are advantageous in that they reduce air pressure about 5:1 rather than the pitot tube's 10:1 (meaning yes, less drag in some sense) but on such a tiny scale it makes barely any difference. On the flip side, pitot plates have very inaccurate readings at lower speeds (though so low that it probably would not matter for any jet aircraft). Also, it is to my knowledge that pitot plates are used mainly for fluid research, sometimes not even related to aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since pitot tubes are relatively small compared to the size of an aircraft and are streamlined anyway, there would be little to no noticeable improvement in aerodynamics. You would think that jetliners have completely clean surfaces, but guess again:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/wmLP5.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Removing a pitot tube won't make a difference. Note: the gray circles outlined in dotted red boxes are pitot-static ports, which, combined with an aircraft's pitot tubes, make up the pitot-static system. They can measure air pressure for both airspeed and altitude among other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Final thing I wanted to clear up: flat surfaces are generally less aerodynamic than curved surfaces. Someone got too much of that idea when designing this plane... /s&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.kinja-img.com/gawker-media/image/upload/s--NN8W_sig--/c_fit,fl_progressive,q_80,w_636/sgo8y89son1tglbmf9oa.jpg&quot; alt=&quot;&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="8282" LastEditDate="2019-01-31T12:13:46.963" LastActivityDate="2019-01-31T12:13:46.963" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19320" PostTypeId="2" ParentId="19312" CreationDate="2015-08-25T21:57:38.653" Score="2" Body="&lt;p&gt;As far as I know, nobody actually maintains a register of go around. A go around is not a failure, nor a fault.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However each missed approach reduces the fuel quantity which may become insufficient. The crew will not continue to try to land at the same airport if the likelihood of better conditions at the alternate airport are high.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-08-25T23:19:48.730" LastActivityDate="2015-08-25T23:19:48.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19321" PostTypeId="2" ParentId="19316" CreationDate="2015-08-25T22:47:01.430" Score="8" Body="&lt;p&gt;Airway data is published in each country by their respective regulatory authority. This is published as a part of AIP(Aeronautical Information Publication).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeronautical_Information_Publication&quot;&gt;page&lt;/a&gt; contains links to some of the sites having electronic AIPs. The relevant data can be found in Part 2- Enroute(ENR). For example, &lt;a href=&quot;http://www.ead.eurocontrol.int/eadbasic/eais-2C49EA3CFCE624721786D2DB28A07346/3QDXTD5E6YWTY/EN/2015-08-20-AIRAC/html/index-ead-en-GB.html?target=eAIP/EG-GEN-0.1-en-GB.html&quot;&gt;this&lt;/a&gt; gives the details for UK airways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think there is a worldwide list as the airways of each country is controlled by the respective government through regulatory body and this information is updated periodically (in cycles of 28 or 56 days).   &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-25T22:47:01.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19322" PostTypeId="2" ParentId="19316" CreationDate="2015-08-25T22:51:39.713" Score="4" Body="&lt;p&gt;If it's not for real-world use, navigraph.com publishes a regular database of  worldwide airways, navaids, airports, SIDs and STARS, etc.  &lt;/p&gt;&#xA;" OwnerUserId="9957" LastActivityDate="2015-08-25T22:51:39.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19323" PostTypeId="1" AcceptedAnswerId="19348" CreationDate="2015-08-25T23:22:03.753" Score="4" ViewCount="2549" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JdAdL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JdAdL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in this picture the bottom of the fuselage curves upwards to form the nose.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="4197" LastEditDate="2015-08-26T12:36:26.243" LastActivityDate="2019-02-01T21:53:55.117" Title="Why does the bottom part of an aircraft nose curve upwards?" Tags="&lt;aerodynamics&gt;&lt;airliner&gt;&lt;nose&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19324" PostTypeId="1" AcceptedAnswerId="19328" CreationDate="2015-08-25T23:30:06.300" Score="4" ViewCount="1418" Body="&lt;p&gt;I wonder this because I'm not too sure glass is easier for air to travel over than metal.&lt;a href=&quot;https://i.stack.imgur.com/TEYex.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TEYex.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2017-12-04T15:55:52.957" Title="Do windows on the side of the fuselage increase drag?" Tags="&lt;airliner&gt;&lt;windows&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19326" PostTypeId="2" ParentId="7485" CreationDate="2015-08-25T23:57:15.690" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.airforce.mil.nz/nr/exeres/c041d639-84d0-48bf-afa7-9e030ff6bcf8.htm&quot; rel=&quot;nofollow&quot;&gt;The RNZAF have in recent years flown 757's to and from a permanent ice runway in Antartica&lt;/a&gt; . The runway is 10,000 feet long and has lights etc but I thought it might qualify as a &quot;rough runway&quot;. There are lot of better pictures than the one I've linked to if you use an image search.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationweek.com/commercial-aviation/engineering-judgment-key-757-forced-landing-antarctica&quot; rel=&quot;nofollow&quot;&gt;They had a difficult flight in October 2013&lt;/a&gt; which &lt;a href=&quot;http://www.3news.co.nz/nznews/boeing-757-antarctica-flights-review-needed--taic-2015012910#axzz3jsG2Lvmb&quot; rel=&quot;nofollow&quot;&gt;has put into question&lt;/a&gt; the future of these operations. The difficultly was not related to the nature of the runway but to the lack of landing alternatives in the event the weather goes the wrong way.&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="4007" LastEditDate="2015-08-26T00:10:41.093" LastActivityDate="2015-08-26T00:10:41.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19328" PostTypeId="2" ParentId="19324" CreationDate="2015-08-26T00:01:25.450" Score="11" Body="&lt;p&gt;The simple answer is yes, but it is not the material that makes the difference in drag production.  The difference between painted aluminum or composite surfaces and glass is negligible.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where there are windows, there are likely to be seams, transitions and other variations in the skin of the aircraft.  These variations can cause turbulence in the air flowing over the skin which can induce drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why gliders have such smooth surfaces and contours.  The airflow remains attached to the surface in laminar flow which minimizes drag.  Even bugs stuck to the leading edge of the wing can degrade performance.&lt;/p&gt;&#xA;" OwnerUserId="1694" LastActivityDate="2015-08-26T00:01:25.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19329" PostTypeId="1" AcceptedAnswerId="19337" CreationDate="2015-08-26T00:39:19.677" Score="14" ViewCount="5708" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KfL8g.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KfL8g.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image shows the A350 first takeoff high in the air and the landing gear is still down. Why didn't they retract it?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="21128" LastEditDate="2020-02-03T14:27:25.350" LastActivityDate="2020-02-03T14:27:25.350" Title="Why doesn't the landing gear get raised on the first flight of a new airplane?" Tags="&lt;airliner&gt;&lt;landing-gear&gt;&lt;new-airplane&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="19331" PostTypeId="1" AcceptedAnswerId="19334" CreationDate="2015-08-26T02:40:59.280" Score="-1" ViewCount="200" Body="&lt;p&gt;On snowy days the pilots well say to put on the de-icing on both engines how does this work?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-26T05:08:39.840" Title="How does de-icing work in an airliners engine" Tags="&lt;airliner&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-08-26T05:46:12.873" ContentLicense="CC BY-SA 3.0" />
  <row Id="19333" PostTypeId="1" AcceptedAnswerId="19418" CreationDate="2015-08-26T04:43:32.133" Score="8" ViewCount="1669" Body="&lt;p&gt;The B-52 and other big aircraft often fly long missions.&#xA;What does the crew eat or drink?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a list of recommended things to eat, or of specific foodstuff to avoid?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is it stored onboard?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="15311" LastEditDate="2018-01-02T07:16:45.657" LastActivityDate="2018-01-02T07:16:45.657" Title="What does the crew of a long range miltary aircraft eat during a mission?" Tags="&lt;military&gt;&lt;bomber&gt;" AnswerCount="2" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="19334" PostTypeId="2" ParentId="19331" CreationDate="2015-08-26T05:08:39.840" Score="2" Body="&lt;p&gt;In simple terms, hot bleed air from the engine is ducted around the engine to prevent ice from forming. It is also directed through valves and ducting to the leading edges of the wings.&lt;/p&gt;&#xA;" OwnerUserId="9961" LastActivityDate="2015-08-26T05:08:39.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19335" PostTypeId="2" ParentId="19313" CreationDate="2015-08-26T05:28:09.783" Score="22" Body="&lt;p&gt;If you have &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot; rel=&quot;nofollow noreferrer&quot;&gt;24 wheels&lt;/a&gt; to spread the load out, even 400 tons might not be too heavy. Especially when the tire pressure can be adjusted from the cockpit (however, reducing tire pressure quickly lowers the MTOW of the An-124). See &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2842157/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; for some hearsay on the issue.&lt;/p&gt;&#xA;&lt;p&gt;The aircraft designers keep &lt;a href=&quot;https://aviation.stackexchange.com/a/7496/1696&quot;&gt;tire pressure&lt;/a&gt; low to enable this. Everything below 80 psi should have no problem on a dry grass strip. Gliders have around 50 psi and use grass strips (and the next available field, if needed) routinely. When tire pressure exceeds 100 psi, I would look more closely at the grass strip - if the soil is hard enough, why not land there? The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-130&lt;/a&gt; has a tire pressure of 125 psi (8.6 bar) and routinely operates from unpaved strips.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4CcNi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4CcNi.jpg&quot; alt=&quot;Polish Air Force C-130E with serial 1502 during grass strip take-off and landings on 4 April 2014&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Polish Air Force C-130E with serial 1502 during grass strip take-off and landings on 4 April 2014&#xA;(Image © Capt. Włodzimierz Baran / Dowódca Generalny Rodzajów Sił Zbrojnych)&lt;/p&gt;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=4ivH7tLiFLY&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; of an Illyushin 62 landing in a field. Note that it was not anywhere near its maximum flight mass at this event. It was the last flight of this bird; now it sits idle as a tourist attraction in the German countryside.&lt;/p&gt;&#xA;&lt;p&gt;However, I once landed an &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASW_20&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASW-20 C&lt;/a&gt; on a muddy field soaked after days of rainfall. The wheel immediately dug in and the aircraft slid for 20 meters along the bottom of the forward fuselage. It took me a week to repair the cracks - the ASW-20 has a great landing gear, but is poorly suited to plough like this through a muddy field.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="22871" LastEditDate="2021-04-29T13:35:36.357" LastActivityDate="2021-04-29T13:35:36.357" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19336" PostTypeId="2" ParentId="19295" CreationDate="2015-08-26T06:56:08.037" Score="1" Body="&lt;p&gt;A fail of the GPS system wouldn't cause any issue to properly trained pilots. Remember that aviation started in the early twentieth century! However if you have no visibility and all the navigation systems (or, more probably, just the pilots) fail, then you are in trouble and you can eventually crash. Just a couple of examples from the top of my head:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If you get completely lost at night in the middle of the Amazon forest you will probably run out of fuel and crash (see Varig Flight 254). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you think that your navigation system is guiding the plane while it's accidentally off, you may end up on a nearby hill instead of the runway (see First Air Flight 6560 - note that even the GPS was working correctly but the pilots were confused).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2345" LastEditorUserId="8112" LastEditDate="2015-08-26T09:06:26.693" LastActivityDate="2015-08-26T09:06:26.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19337" PostTypeId="2" ParentId="19329" CreationDate="2015-08-26T07:14:32.983" Score="30" Body="&lt;p&gt;Test flying is thoroughly planned, and of the many things to test during development, the landing gear is just a minor part. In the first flight the goal is to check out basic functionality and how well the low-speed performance was predicted. The landing gear can wait for one of the later flights. You can see in the photo of the A350 that the slats are extended and the flaps are in take-off position. The pilots are busy testing handling in take-off configuration, and for that the gear must be down. You can be sure that they also tested the landing configuration at altitude before going down to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the tested &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_envelope&quot;&gt;envelope of the aircraft&lt;/a&gt; will be expanded step by step. Since every flight will contain a take-off segment, it is prudent to check out this part of the envelope first. Once the low-speed regime is tested, consecutive flights will take the aircraft to higher speeds, and only then will it be necessary to retract the gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the first flight of a newly developed aircraft has become a ceremonial affair. After having spent hundreds of millions of dollars or euro, and with all the media attention, nobody wants to live through the embarrassement of a gear failure on occasion of the first flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was not always the case. The &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot;&gt;F-100&lt;/a&gt; went supersonic on its second flight; taking this kind of risk would be unimaginable today without the pressure of an arms race.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-26T12:08:03.937" LastActivityDate="2015-08-26T12:08:03.937" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19338" PostTypeId="1" CreationDate="2015-08-26T07:54:46.710" Score="19" ViewCount="2872" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/7486/1467&quot;&gt;this answer&lt;/a&gt; gravel kits are mentioned. I then looked at the &lt;a href=&quot;http://en.wikipedia.org/wiki/Gravelkit&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia page&lt;/a&gt; and I noticed that they are quite different from what I was expecting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gravelkit#/media/File:737-200_Gravelkit.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oyMrZ.jpg&quot; alt=&quot;Gravel kit tube in front of engine intake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was expecting some kind of &quot;shield&quot;, plate or extended inlet on the bottom side of the engine.&#xA;Wikipedia says that these instead are&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;vortex dissipators, using compressor bleed air&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How do they work? How does a beam and a sidewise jet of air prevent FOD ingestion?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-07-05T15:01:22.383" Title="What is the working principle of gravel kits?" Tags="&lt;jet-engine&gt;&lt;inlet&gt;&lt;vortex&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19339" PostTypeId="1" CreationDate="2015-08-26T08:11:59.160" Score="3" ViewCount="167" Body="&lt;p&gt;The classic book is awesome but I do know some of the terminology is outdated and perhaps some other things.  Is there a site etc. that keeps track of what's outdated in the book &quot;Stick and Rudder&quot; and what the newest equivalent terms?&lt;/p&gt;&#xA;" OwnerUserId="870" LastActivityDate="2015-08-31T10:43:25.543" Title="Is there a resource that lists what's outdated in &quot;Stick and Rudder&quot;?" Tags="&lt;books&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19340" PostTypeId="2" ParentId="19338" CreationDate="2015-08-26T09:09:13.823" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Vortex Dissipators&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Prevent vortices forming at the engine intakes which could cause gravel to be ingested by engine. These consist of a small forward projecting tube which blows pressure regulated (55psi) engine bleed air down and aft from 3 nozzles at the tip to break up the vortices.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.b737.org.uk/unpavedstripkit.htm&quot;&gt;Source&lt;/a&gt;&#xA;&lt;br&gt;&#xA;So basically it works by blowing air out of the tube to prevent vortices from forming. It is the vortex that sucks the stones up. No vortex = no FOD. The 'shield' kind of protection is installed on nose gear to prevent damage to the under belly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;**note main gear is behind engines so no FOD from main gear affect engines.&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="679" LastEditDate="2015-08-26T12:08:28.503" LastActivityDate="2015-08-26T12:08:28.503" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19341" PostTypeId="2" ParentId="19339" CreationDate="2015-08-26T09:25:17.520" Score="4" Body="&lt;p&gt;I'm not aware of such a list although I would say 99.99% of this book is not outdated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe some of the terminology is outdated when it talks about the &quot;gaits&quot; of the aeroplane for example which is an horse term apparently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wouldn't say anything else is though certainly not the concepts, because the air is the same, the laws of physics are the same and human nature the same as it was 70 years ago. Its a very insightful book that should be every pilots reading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe it goes on more about tail-wheel aircraft and there are fewer of these aeroplanes around today but this only applies on the ground and is still very interesting even for nose dragger pilots like me.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-26T09:25:17.520" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19342" PostTypeId="2" ParentId="19254" CreationDate="2015-08-26T11:17:27.990" Score="3" Body="&lt;p&gt;Possible reasons of failure include (in no particular order):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Running out of fuel&lt;/li&gt;&#xA;&lt;li&gt;Not having the fuel turned on - the engine might fail just after you have lifted off - so don't change tanks after your power checks&lt;/li&gt;&#xA;&lt;li&gt;Fuel pump failure (many low wing aircraft have two pumps)&lt;/li&gt;&#xA;&lt;li&gt;Mechanical failure of the engine&lt;/li&gt;&#xA;&lt;li&gt;A propeller blade flying off - you want to stop the engine immediately so that the engine doesn't shake itself out of the aeroplane - if this happened, the aircraft would not be controllable and the end result very bad&lt;/li&gt;&#xA;&lt;li&gt;In Flight Engine Fire. Not only would you want to stop the engine, you might like to do an emergency descent, which gets the aircraft on the ground as quickly as possible without excess airspeed&lt;/li&gt;&#xA;&lt;li&gt;Ignition system failure that causes either a full power loss or partial (back firing, rough running)&lt;/li&gt;&#xA;&lt;li&gt;A passenger touching the throttle or mixture control&lt;/li&gt;&#xA;&lt;li&gt;Failure of the exhaust system - leaking exhaust is hot and in the engine compartment could cause a fire or failure.&lt;/li&gt;&#xA;&lt;li&gt;Broken throttle cable leaving the engine at the last power setting (could be too high or too low for a safe landing and/or continued flight).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I am sure there are many more. There might be also other reasons such as lack of daylight, bad weather, or a problem with the aircraft where you may prefer to carry out a forced landing in a field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you do about a sudden failure depends how close to the ground you are. You must fly the aircraft first - Aviate - Navigate - Communicate. So if the engine fails at 100 feet you must look where you are going and aim to reach the ground under control, even if that means hitting something. Much better than to lose control, stall or spin and hit the ground out of control - this will likely kill you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If its an engine failure just after take off. Have your own limits as to when it is safe to turn back. Remember you might be turning back into oncoming traffic so its not always the best option even if you do have enough height. My personal limits are that if I have already turned 90 degrees in the circuit and my height is 500 feet AGL or above then I might consider a turn back. This is something you can practice at altitude with an instructor to get it clear in your mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have enough height, the first thing to see is if the propeller has stopped turning. Airflow will normally keep it turning so if it has stopped the engine might have a mechanical problem that means it will never re-start. If the propeller is still turning, fly the aircraft first and foremost but it is worthwhile memorising the emergency checklist. This might include (from my memory, i.e. not to be relied upon):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carb Heat - On&#xA;Mixture - Rich (you may have leaned it out too much and caused a failure, or descended with lean mixture making it even leaner)&#xA;Fuel Pump - on (maybe the engine driven pump has failed)&#xA;Change Tanks in case one is empty or blocked&#xA;Throttle position - check it hasn't vibrated to an idle setting (your hand should be on the throttle during take off to prevent this)&#xA;Magnetos - maybe one has failed the engine may run well on one or the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't forget your pre landing checks if it still doesn't start!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you get closer to the ground close the throttle and forget about it - your attention must be flying the aircraft and landing as safely as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a twin is harder, because you must learn how to fly it on one engine safely (it will pull one way or another) and this takes experience and currency. Otherwise, rather than you flying the aircraft, the live engine will take you to the scene of the accident. Many twins have single engine safety airspeeds (blue line) which if you go below, you cannot have the live engine on full power otherwise you will lose control due to lack of airflow over the control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some pilots don't touch the engine controls after takeoff until at 500 feet, because there is a slightly increased chance of failure if you do change the power setting for example, or pull the mixture instead of the throttle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A difficult situation can be one where the engine is producing partial power - not quite enough to fly with. You might be tempted to try so you can reach an airport rather than land in a field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Despite writing all this I feel sure I have missed something, hope this helps anyway.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-08-26T12:50:15.857" LastActivityDate="2015-08-26T12:50:15.857" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19344" PostTypeId="2" ParentId="19323" CreationDate="2015-08-26T12:04:12.040" Score="4" Body="&lt;p&gt;The RAF's &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Nimrod&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawker Siddeley Nimrod&lt;/a&gt; does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iRsoF.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iRsoF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Hawker_Siddeley_Nimrod_MR1_(801),_UK_-_Air_Force_AN1047063.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But only because it is an anti-submarine aircraft; its radar is designed to point at the sea, not the air. Of course you could still put weather radar in a downward-pointing nose, but that would be a waste of space and engineering. Commercial aircraft strive for efficiency, and in this case it makes more sense in terms of balanced aerodynamics and instrument placement for a jetliner to have a nose that curves both upwards and downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also take a look at another view:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Gx8He.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gx8He.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://www.airliners.net/photo/UK-Air-Force/Hawker-Siddeley-Nimrod-MR2-801/1688598&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where would you put the baggage? &lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="14897" LastEditDate="2019-02-01T21:53:55.117" LastActivityDate="2019-02-01T21:53:55.117" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="19345" PostTypeId="2" ParentId="19329" CreationDate="2015-08-26T12:04:24.943" Score="7" Body="&lt;p&gt;Aircraft flight testing a rigorous and elaborate affair, with the aircraft first tested at low dynamic pressures and as the performance data is received and analyzed, the flight envelope is expanded slowly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the first flight of test aircraft, the approach is to take minimal risk. Keeping the landing gear extended serves two functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landing gear systems are very complex in themselves and it serves no purpose to check them in the first flight. There is a possibility that they may not retract or may not extend after retracting. As Peter pointed out, this is not a good thing to happen in first flight.&lt;/li&gt;&#xA;&lt;li&gt;Also, in case the aircraft has to land in case of any emergency, it is better to keep the landing gear in extended position.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are a few cases in which the landing gear malfunctioned during the first flight. In the first flight of YF-22, which went on to become the F-22, the landing gear retraction was not planned. However, when it was tried in subsequent flights, the gear did not retract due to software issues. However, it has to be noted that the while retraction was software controlled, extension was hardwired for safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another case of landing gear failure is the NASA dream chaser plane, which suffered landing gear malfunction in its first free flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B4GJa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B4GJa.jpg&quot; alt=&quot;Dream Chaser Landing gear mlalfunction&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft approached the runway, the left landing gear failed to deploy, and the aircraft skidded off the runway and was damaged.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5568" LastEditDate="2015-08-26T22:21:06.307" LastActivityDate="2015-08-26T22:21:06.307" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19347" PostTypeId="1" AcceptedAnswerId="19356" CreationDate="2015-08-26T12:17:12.993" Score="5" ViewCount="2750" Body="&lt;p&gt;If I wish to downgrade my software's design assurance level (DAL) from Level A to Level C, what do I need to do? What are the benefits and drawbacks of doing this?&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="7359" LastEditDate="2015-08-26T14:54:06.273" LastActivityDate="2015-08-26T17:22:14.863" Title="What do I do if I wish to move my software from DAL Level A to DAL Level C?" Tags="&lt;aircraft-systems&gt;&lt;software&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19348" PostTypeId="2" ParentId="19323" CreationDate="2015-08-26T12:25:12.470" Score="6" Body="&lt;p&gt;Having the tip of the nose in the centre gives best combination of aerodynamic performance, weight and internal volume. If you move the tip down, the slope above it will either be steeper, leading to higher drag, or longer, leading to greater length and thus weight; or you don't extend the plane, but then the longer sloped part will provide less internal volume. Only the cockpit windows, which need to be on the sloping part, shift the nose a bit down, to the centre of the cross-section just before cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cars are different. For a car you want the bottom surface flat, because you don't want to push and compress air in the gap between the vehicle and the ground. But aircraft has air all around and it is most efficient for it to push air equally to all sides, so a circularly symmetrical shape works best.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that lift is yet another thing. Lift requires a sharp, downward-sloped &lt;em&gt;trailing&lt;/em&gt; edge.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-08-26T12:32:24.587" LastActivityDate="2015-08-26T12:32:24.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19349" PostTypeId="2" ParentId="572" CreationDate="2015-08-26T12:33:35.787" Score="8" Body="&lt;p&gt;I think one has to abandon the idea of shock cooling as a single event which will cause a cylinder immediately to crack. Instead one has to think about it as cyclic thermal fatigue where material damage will be accumulated incrementally through a number of such cyclic events. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thermal cycles are an inherent part of the normal wear &amp;amp; tear that any IC engine has to endure and which in the end results in a  finite TBO instead of infinite engine life.  Start up of a cold engine, shut down of a hot engine or major changes in power setting belong to a normal operation cycle.  The specified TBO of an engine implicitely contains a certain number of thermal cycles of these kinds that can be sustained without premature failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbine manufacturers who are dealing with similar life limiting problems take a more sophisticated approach and explicitely include both the number of cycles and the number of (continous duty) operating hours into their maintenance interval (=TBO) considerations. Furthermore the severity of different events is considered by applying respective weight factors. A cold start e.g. costs more engine life than a warm startand therefore has a higher weight factor. &#xA;Now the analogy to the shock cooling issue should become apparent. In general each power reduction of a hot engine after a climb under fully power represents a thermal fatigue cycle for certain parts of the engine but the amount of incremental damage caused by this fatigue cycle is determined by a number of factors: How hot is the engine and how fast the is power being reduced. If it is done aggressively then the incremental damage will be significantly bigger than the damage caused by a gentle and gradual power reduction. Thus the engine will consume a disproportionate amount of its total life compared to a more careful handling. A crack will not form immediately but an engine that is treated in such a harsh manner on a regular basis will for sure not reach the full TBO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few words regarding the physics of thermal fatigue and cracking: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not the cooling rate per se that counts but the temperature gradients that are built up during cooling, i.e. the inhomogeneity of the temperature field. Thermal stresses are caused by regions within a structure where free thermal expansion (or shrinkage) is constrained by strong temperature gradients. Strong temperature gradients are either caused by rapid heating or rapid cooling. In both cases high heat transfer coefficients are required. In case of rapid cooling high heat transfer coefficients are e.g. caused by a strong airflow inside the cowling as a direct consequence of a high air speed.&#xA;The situation is aggravated in regions where materials with different thermal expansion coefficients are mating (AL and steel) or at locations with high stress concentrations (notches, sharp corners).&#xA;On the other hand the susceptibility of a metal to fatigue damage  depends on the absolute temperature level at which the thermal stresses occur. The same temperature gradient in a hot piece of metal is significantly more damaging than if the metal is in a colder state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we have all ingredients to get a better understanding of what shock cooling really means: &#xA;An engine that is very hot after a prolonged period of climbing under full power undergoes a rapid power reduction and simultaneously the plane is accelerated to a  high airspeed (imagine the descent of a tug plane after an aero tow). The airflow inside the cowling is significantly increased and the engine is cooled down rapidly (and inhomogeneously). The resulting heat flux induces temperature gradients and consequential thermal stresses in the structure. While for most of the structure these thermal stresses are insignificant there are a few life limiting spots like exhaust valve seats etc. where a certain amount of fatigue damage is evolving due to these stresses. The actual amount of fatigue damage is determined by the severity of the event, i.e. the hotter the engine, the more aggressive the power reduction after the climb and the faster the acceleration of the plane, the more damage will be induced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming to my initial statement: I don't believe in shock cooling as a single event that could cause cylinder head cracking in one go but I do definitely believe that such events as described above consume a disproportionate amount of engine life and premature cracking is very likely if this sort of  mission profile is repeated too frequently.&lt;/p&gt;&#xA;" OwnerUserId="9968" LastActivityDate="2015-08-26T12:33:35.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19350" PostTypeId="2" ParentId="19338" CreationDate="2015-08-26T13:00:01.660" Score="18" Body="&lt;p&gt;Notice the path of condensation leading up from below this engine into it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/roEbj.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/roEbj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That image was taken from &lt;a href=&quot;https://www.youtube.com/watch?v=VUDu9n2bsjQ&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt;, and it clearly demonstrates that there exists a path of air which flows from ground level up into the engine. Any debris on the ground is liable to be sucked up in that vortex. The nozzle is designed to break up the flowing air on that specific, well-known path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that even when there is no condensation to make the vortex visible and obvious, it still might exist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice &lt;a href=&quot;https://youtu.be/cEgiqCZLJqQ?t=3m11s&quot; rel=&quot;noreferrer&quot;&gt;intake vortex video&lt;/a&gt;, and here you can see the &lt;a href=&quot;https://www.youtube.com/watch?v=jGl39IEnTuY&quot; rel=&quot;noreferrer&quot;&gt;vortex swirling on the ground&lt;/a&gt;. This video really shows off a &lt;a href=&quot;https://www.youtube.com/watch?v=QIZcTVz60rA&quot; rel=&quot;noreferrer&quot;&gt;C-17's huge vortex during landing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="3727" LastEditDate="2015-08-26T18:12:40.503" LastActivityDate="2015-08-26T18:12:40.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19351" PostTypeId="2" ParentId="18796" CreationDate="2015-08-26T13:01:35.360" Score="2" Body="&lt;p&gt;On inland bodies of water (lakes, ponds, etc.), as the wind blows across the ground the water will be calm on the side where the wind blows from. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SnZrn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SnZrn.jpg&quot; alt=&quot;Small lake at sunset showing wind direction&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to get a good photo with an iPhone at 10,000 feet, but this shows a pond with calm water on the left and waves on the right. The wind blows from the left. This photo was taken close to sunset so the difference in surface characteristics of the water is pretty dramatic, but this can be seen in just about any light. &lt;/p&gt;&#xA;" OwnerUserId="800" LastActivityDate="2015-08-26T13:01:35.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19352" PostTypeId="2" ParentId="19292" CreationDate="2015-08-26T13:25:18.533" Score="5" Body="&lt;p&gt;It seems to have been done on runways, taxiways and parking stands, though not by using electric resistors, as you suggest. See the following articles from the interwebz:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.icax.co.uk/Solar_Runways.html&quot; rel=&quot;noreferrer&quot;&gt;Interseasonal Heat Transfer&lt;/a&gt; implemented by the company ICAX in Toddington.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://jdasolutions.aero/news-events/news/interest-warms-up.pdf&quot; rel=&quot;noreferrer&quot;&gt;Heated runway concept trials, funded by the FAA&lt;/a&gt;. This includes a portion of a taxiway at O'Hare.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-08-26T13:25:18.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19353" PostTypeId="2" ParentId="19347" CreationDate="2015-08-26T13:39:42.267" Score="7" Body="&lt;p&gt;If you are following &lt;a href=&quot;https://en.wikipedia.org/wiki/DO-178B&quot;&gt;DO-178B&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/DO-178C&quot;&gt;DO-178C&lt;/a&gt;, you can't assign your software a design assurance level (DAL). That is the responsibility of the certification authority, such as the FAA in the US, Transport Canada in Canada, or EASA in Europe. There are analysis methods that are used to determine the appropriate level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a certification authority does downgrade your design assurance level, you will need to meet fewer objectives and fewer objectives satisfied with independence. An objective satisfied with independence means that the development processes and the verification and validation processes are carried out independently. Lower design assurance levels always have fewer objectives and fewer objectives with independence than the higher levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have software that is designed and certified at DAL Level A, then it can be used in place of software certified at any lower DAL level.&lt;/p&gt;&#xA;" OwnerUserId="7359" LastActivityDate="2015-08-26T13:39:42.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19354" PostTypeId="1" AcceptedAnswerId="19355" CreationDate="2015-08-26T14:14:37.670" Score="4" ViewCount="445" Body="&lt;p&gt;Airbus test their plane on &lt;a href=&quot;https://en.wikipedia.org/wiki/Toulouse%E2%80%93Blagnac_Airport&quot; rel=&quot;nofollow&quot;&gt;Toulouse Airport&lt;/a&gt;, and Boeing test on &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Field&quot; rel=&quot;nofollow&quot;&gt;Boeing field&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about Russian airliners Ilyushin &amp;amp; Tupolev and Chinese Airliners &lt;a href=&quot;http://Comac&quot; rel=&quot;nofollow&quot;&gt;Comac&lt;/a&gt; ?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="1961" LastEditDate="2015-08-26T16:00:42.210" LastActivityDate="2015-08-26T22:27:38.487" Title="Where do Russian and Chinese airliner manufacturers test their airliners?" Tags="&lt;airliner&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19355" PostTypeId="2" ParentId="19354" CreationDate="2015-08-26T15:06:38.927" Score="9" Body="&lt;p&gt;Almost all Russian (Soviet) aircrafts were tested in the Zhukovsky Airfield (Ramenskoye Airport) near Moscow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Comac is building a Flight Test center at Dongying, Shandong province near the Dongying Shengli Airport. The flight test of aircrafts are expected to be carried out from here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Peter noted, Antonov test their aircrafts at Kiev Airport, including An 225, the largest aircraft in world.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-08-26T22:27:38.487" LastActivityDate="2015-08-26T22:27:38.487" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19356" PostTypeId="2" ParentId="19347" CreationDate="2015-08-26T17:22:14.863" Score="17" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If I wish to downgrade my software's design assurance level (DAL) from Level A to Level C, what do I need to do? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;DAL level A software is software which, if it fails, may have &lt;em&gt;&quot;catastrophic&quot;&lt;/em&gt; results, defined as &lt;em&gt;&quot;Failure may cause multiple fatalities, usually with loss of airplane.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DAL level C, &lt;em&gt;&quot;Failure significantly reduces the safety margin or significantly increases crew workload. May result in passenger discomfort (or even minor injuries).&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to move your software from DAL level A to DAL level C, you'll have to reduce the responsibility of your software.  Your software's operation or failure to operate cannot:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;result in passenger major injury or fatality&lt;/li&gt;&#xA;&lt;li&gt;produce a large negative impact on safety or performance of the aircraft&lt;/li&gt;&#xA;&lt;li&gt;reduce the ability of the crew to operate the aircraft due to physical distress or higher workload (though significant increases in workload is acceptable at Level C)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At most, your software's operation or failure to operate may:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Significantly reduce safety margins&lt;/li&gt;&#xA;&lt;li&gt;Significantly increase crew workload&lt;/li&gt;&#xA;&lt;li&gt;Result in passenger discomfort or minor injury&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you can change your software, or change your customer's use of the software (ie, cannot be used or installed as part of a safety critical control system), then the certifying authorities may allow your software to be certified at Level C.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the benefits and drawbacks of doing this?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are only 62 objectives that have to be met, and of those only 8 have to be verified by someone independent of the person who implemented the code that falls under that objective. While the number of objectives is only reduced a little (71 vs 62), the number requiring independent verification is cut by over 75% from 33 to 8. This significantly reduces the amount of work required to meet certification requirements, mostly in traceability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major drawback is that your software cannot be used or incorporated into systems which require a higher level of compliance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if your software is designed to control actuators and is currently certified to Level A, you might find that it's being used to control flight surfaces on some planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The move to Level C may, in that case, not require any software changes at all.  If you stop performing the full traceability, tests, and meeting objectives with independence at Level A, and only perform those necessary for Level C, then your release under this new system will necessarily only be certified under Level C.  The software can no longer be used to control flight surfaces, but if a new plane comes out with electronically adjustable air nozzles in the passenger compartment, it may be eligible for inclusion there where failure would, at worst, cause passenger discomfort and increase crew workload managing complaints about air vents being misdirected or opened/closed when the opposite is desired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your software is an autopilot, though, then it will never be used if it doesn't meet Level A.  In this case, there's no way to change your software or process to a lower level and expect it to be used - the usage of the software defines the level to which it must comply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most cases, the usage will drive which level the software must be certified to, and there's no real way (or reason) for you to change your level.  It would cease to be useful software at the wrong level.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2015-08-26T17:22:14.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19357" PostTypeId="2" ParentId="19329" CreationDate="2015-08-26T18:57:37.717" Score="4" Body="&lt;p&gt;The simple and easy answer is that the first of any new aircraft design, no matter how well-engineered, well-constructed and/or derivative of earlier designs, is a complete unknown. The first flight is always gear-down because if there's any problem, the test pilot/crew needs to be able to get the plane back down on the ground without having to deal with any additional issues (like not being able to get the gear back down). Gear extension, retraction and emergency release are all thoroughly tested many, many times with the aircraft on a lift prior to the first flight, but still, anything can happen, and better safe than sorry (especially in a civilian aircraft design without an ejection system).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-26T18:57:37.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19358" PostTypeId="2" ParentId="19323" CreationDate="2015-08-26T20:55:09.947" Score="0" Body="&lt;p&gt;Just to add to other answers, evenly sloped fuselage on the top and bottom in the front of the aircraft would create lift and drag somewhat equally in top and bottom direction, thus rendering fuselage aerodynamically neutral like BillOer mentioned in comments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were to design fuselage like the vehicle below, downforce generated by the upper part of the fuselage would push the whole assembly downwards - this is desirable for road vehicles as the more planted on the road they are, the better. For aircrafts however, balance is the key:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DGnAg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DGnAg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9146" LastEditorUserId="755" LastEditDate="2015-08-26T21:04:06.273" LastActivityDate="2015-08-26T21:04:06.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19360" PostTypeId="1" AcceptedAnswerId="22555" CreationDate="2015-08-26T21:28:03.087" Score="5" ViewCount="8597" Body="&lt;p&gt;The diagram shows the B777-200LR Payload/Range for 0.84 Mach Cruise (P.41 of &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/777_2lr3er.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9Afsa.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Afsa.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum payload range is around 7600 nmi, and after that payload have to be reduced in order to increase range. &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777#Specifications&quot; rel=&quot;noreferrer&quot;&gt;While the Operating empty weight of 777-200LR is 320Klbs&lt;/a&gt;, the horizontal-coordinate(range) of the diagram is around 10500nmi at 350Klbs, and there is a gap of 30Klbs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does that mean B777-200LR has theoretical maximum range over 10500 nmi if OEW plus payload is below 350Klbs? And how far can it fly potentially?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-08-26T21:34:48.810" LastActivityDate="2017-01-11T16:03:48.333" Title="How far can Boeing 777-200LR fly?" Tags="&lt;boeing-777&gt;&lt;range&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19361" PostTypeId="1" AcceptedAnswerId="19362" CreationDate="2015-08-26T22:18:26.003" Score="15" ViewCount="12167" Body="&lt;p&gt;The first airplane by the Wright brothers had a double wing. This concept continued through World War 1 and into the 1930s - why was this concept popular?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kZUsE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kZUsE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="6886" LastEditDate="2015-08-26T22:54:00.653" LastActivityDate="2020-10-22T20:44:05.040" Title="Why do older airplanes have a wing on both the top and the bottom of the aircraft?" Tags="&lt;aviation-history&gt;&lt;biplane&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19362" PostTypeId="2" ParentId="19361" CreationDate="2015-08-26T22:38:39.733" Score="27" Body="&lt;p&gt;Mainly for strength. Up to about 1920, wings used very thin airfoils and were mainly made of fabric stretched over a wooden frame. The main spar was too thin and would have been prone to bending if it had had to support the whole weight of the aircraft in a single span. Only by using two wings, the upper as the compression member and the other as the tension member of a truss, the needed strength was possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0xkNt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0xkNt.jpg&quot; alt=&quot;Airfoil thickness comparison by D.R. Kirk, Florida Institute of Technology&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airfoil thickness comparison by D.R. Kirk, Florida Institute of Technology (picture &lt;a href=&quot;http://slideplayer.com/slide/3520095/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your photo, you can just about see the wires running from the top wing (near the outboard struts) to where the bottom wing joins the fuselage. These wires take most of the strain in flight, spreading the load on the wings. It's the same principle as using triangles in the construction of electricity pylons or bridges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Monoplanes of that time needed even more wire bracing. Look at the picture of a replica of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Etrich_Taube&quot; rel=&quot;noreferrer&quot;&gt;Etrich Taube&lt;/a&gt;, a very popular plane of the pre-WW I period.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EGdAc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EGdAc.jpg&quot; alt=&quot;Etrich Taube in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Etrich Taube in flight. Note the truss below the wing and the many wires keeping it in shape (picture &lt;a href=&quot;http://www.bredow-web.de/ILA_2004/Traditionsflugzeuge/Etrich_Taube/Flug-Taube/flug-taube.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shorter wingspan of a biplane also reduces the load on the wings. Biplanes tend to have a lot of lift (for their size) because of the large wing area, but also a lot of drag, so they're quite inefficient overall. There were also triplanes, with three mainplanes for even more lift in the same wingspan. WW I pilots demanded the highest rate of roll, which could best be achieved with biplanes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the time between the World Wars, the use of high-strength aluminium for aircraft and the monocoque airframe both allowed airframes to become stronger. This meant that monoplane designs became more practical, even though the older aviators didn't believe a monoplane could be strong enough. As soon as monoplanes were practical, the improvements in efficiency and flight performance saw them replace bi- and tri-planes.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="1961" LastEditDate="2015-08-28T12:55:17.793" LastActivityDate="2015-08-28T12:55:17.793" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19363" PostTypeId="2" ParentId="19323" CreationDate="2015-08-26T22:50:54.990" Score="4" Body="&lt;p&gt;The nose of the aircraft has to satisfy a number of requirements, some of them contradictory, like&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The nose shape should produce the least drag&lt;/li&gt;&#xA;&lt;li&gt;The pilots should have good visibility&lt;/li&gt;&#xA;&lt;li&gt;It should house the weather radar and related avionics&lt;/li&gt;&#xA;&lt;li&gt;The cockpit noise should be minimal&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For example, the aerodynamic design of Concorde meant that the nose had to droop during takeoff/landing for good pilot visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircrafts flying in transonic regime, some of the best nose shape from aerodynamic standpoint would be to have a symmetric body of evolution based on Haack series of curves. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/05C3d.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/05C3d.png&quot; alt=&quot;Haack Curves&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Nose_Cone_Haack_Series.svg#/media/File:Nose_Cone_Haack_Series.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nose Cone Haack Series&lt;/a&gt;&quot; by Andersenman - Created with Gnuplot using the Haack series formula and a selection of input values for C relevant to the article. Values are 0, 0.333, 0.667, 1 and 1.333.. Licensed under CC0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, due to fact that the cockpit is on the upper part of the nose region, this arrangement increases the complexity of cockpit windows (they will have to be curved in two axes, atleast) if the pilot has to have good visibility. As a result, center of the the nose is usually moved downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason for the common profile seen in aircraft noses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the disadvantage of this profile is that the pressure is high in the windshield region compared to the flat profile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/D7Lff.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D7Lff.png&quot; alt=&quot;Curved Vs Flat Cabin&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source:AGARD LS-67, Paper-4&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main problem with (dual) curved cockpit windshield is the tighter quality control required and the associated costs. However, in 787, Boeing has achieved a continuous surface variation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Nn7Sm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nn7Sm.jpg&quot; alt=&quot;787 Nose&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: airliners.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is to be noted that the aerodynamics is only one of the criteria for nose design. For example, a nose with similar profile to that of 787 was proposed for A350. However, it was later changed to accommodate other considerations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ijKvi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ijKvi.jpg&quot; alt=&quot;A350 nose profile change&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: airliners.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Didier Evrard, executive vice-president A350 programme,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There have been a number of trade-offs in the nose area, enabling us to maximise the volume of the cockpit and avionics bay while optimising aerodynamics and the positioning of the nose landing gear&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I7q3a.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I7q3a.png&quot; alt=&quot;A350 nose&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A350xwb_nose_2009B.png#/media/File:A350xwb_nose_2009B.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;A350xwb nose 2009B&lt;/a&gt;&quot; by Luis E. Contreras. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-27T12:09:53.550" LastActivityDate="2015-08-27T12:09:53.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19364" PostTypeId="1" AcceptedAnswerId="19367" CreationDate="2015-08-26T23:04:31.870" Score="4" ViewCount="295" Body="&lt;p&gt;The V-22 has blades that are larger than blades on most helicopters. Could you make them smaller and still have the vertical takeoff effect?&lt;a href=&quot;https://i.stack.imgur.com/LotH0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LotH0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus: Does the V-22 get some of its thrust from the exhaust?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9731" LastEditDate="2015-08-26T23:15:39.953" LastActivityDate="2015-08-27T00:02:22.997" Title="Can the V-22 carryout vertical takeoffs with shorter blades?" Tags="&lt;v-22&gt;&lt;hover&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19365" PostTypeId="1" CreationDate="2015-08-26T23:06:16.660" Score="1" ViewCount="213" Body="&lt;p&gt;What are the major differences (if any) between the air traffic control service in Europe vs. USA vs. Canada?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-08-27T03:21:13.370" Title="Are there differences in air traffic services between western nations?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19366" PostTypeId="2" ParentId="19361" CreationDate="2015-08-26T23:40:33.800" Score="14" Body="&lt;p&gt;The main reason for having multiple wings in the initial years of the aviation was the lack of availability of materials with sufficient strength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of the biplane is that the wings could be shorter for a given lift. During the initial stages of aviation, the materials available for manufacture of aircrafts were timber, doped fabric etc. The structural members made of these did not have enough strength, limiting the wing size. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The early aircraft also had less powerful engines, resulting in lower speed. In this case, the lower stall speed of the biplanes was advantageous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biplanes had very good maneuverability (better roll rate) compared to the monoplanes. This is the reason &lt;a href=&quot;https://en.wikipedia.org/wiki/Triplane&quot; rel=&quot;noreferrer&quot;&gt;triplanes&lt;/a&gt; were developed during the WWWI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fzJAd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fzJAd.jpg&quot; alt=&quot;Sopwith Camel&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:SopTri3.jpg#/media/File:SopTri3.jpg&quot; rel=&quot;noreferrer&quot;&gt;SopTri3&lt;/a&gt;&quot; by &lt;a href=&quot;http://www.earlyaviator.com/archive/a/images/tripe_peggy.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://www.earlyaviator.com/archive/a/images/tripe_peggy.jpg&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&#xA;&lt;/sup&gt;&#xA;However, with the advent of better materials like Aluminum alloys, the aerodynamic disadvantages of biplanes became apparent and monoplanes rapidly became the preferred design choice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the material strength improved, the aspect ratios have become ever bigger, with civil aircrafts facing operational (airport) limitations rather than strength limitations in wing length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the biplanes are still used. The better maneuverability and low stall speed make them popular aerobatic aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-27T13:38:35.583" LastActivityDate="2015-08-27T13:38:35.583" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19367" PostTypeId="2" ParentId="19364" CreationDate="2015-08-27T00:02:22.997" Score="5" Body="&lt;p&gt;The rotor size helicopter (or a tiltrotor, in this case) is determined by its aerodynamic requirements, most importantly, its hover characteristics. The main constraint is the weight that has to be lifted by the helicopter at a give a altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this context, it can be seen that the blades of V-22 are actually &lt;em&gt;smaller&lt;/em&gt;. For example, V22 has a Max. TOW(Take-off Weight) of 27,400 kg. For achieving this, the V22 twin rotors of 11.6 m diameter, giving a rotor disc area of 212 m². A CH47, which has a Max TOW of 22,680 kg has a rotor disc area of 520 m² using twin rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we take single rotor helicopters, the CH 53 Super stallion has a 24 m dia. rotor having a disc area of  460 m² to lift a max TOW of 33,300 kg.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This lesser blade disc area of V22 limits is ability to hover at higher altitudes. The V22 rotor blades will have been optimized for required performance parameters. So, if the blade length is reduced (assuming airfoil is kept the same), vertical takeoff is possible though other performance characteristics will be severely affected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The V 22 uses two Rolls-Royce Allison T406/AE 1107C-Liberty &lt;a href=&quot;https://en.wikipedia.org/wiki/Turboshaft&quot;&gt;turboshafts&lt;/a&gt;, which do not produce any thrust.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-27T00:02:22.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19368" PostTypeId="1" AcceptedAnswerId="19389" CreationDate="2015-08-27T01:38:47.743" Score="6" ViewCount="2408" Body="&lt;p&gt;There are a couple airplanes out there that use the winglet as the rudder, but why doesn't the winglet have a rudder on it to increase the turn of the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oMO8t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oMO8t.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="4197" LastEditDate="2015-08-27T11:15:16.180" LastActivityDate="2016-12-03T19:05:11.493" Title="Why don't airliners have rudders on the winglets?" Tags="&lt;airliner&gt;&lt;rudder&gt;&lt;winglets&gt;&lt;control-surfaces&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19369" PostTypeId="1" AcceptedAnswerId="19371" CreationDate="2015-08-27T01:40:25.070" Score="4" ViewCount="1803" Body="&lt;p&gt;Why do airlines require that phones remain in airplane mode during the final taxi to the gate after landing? As far as I can tell, it does not affect the airplane or anything else negatively or at all. Is this true? If so, then what is the point in keeping the phone in airplane mode until the cabin doors open? Is it just for the sake of convention?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks a lot in advance for any responses!&lt;/p&gt;&#xA;" OwnerUserId="9973" LastEditorUserId="19" LastEditDate="2016-11-03T12:53:33.123" LastActivityDate="2016-11-03T12:53:33.123" Title="Why are passenger required to put their phones in Airplane Mode during taxi to gate?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;commercial-aviation&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19370" PostTypeId="2" ParentId="556" CreationDate="2015-08-27T01:56:16.810" Score="2" Body="&lt;p&gt;Get a smoke hood...Its an extreme No Brainer: read on.&#xA;In a special program Sixty Minutes I believe,  it was explained that most fatalities occur on the ground...Fires, smoke, and were survivable. that is  if you could see, breathe, and your hair was not on fire. You can always use the smoke hood in your hotel as well.  There are a few approved &amp;quot;passive&amp;quot; types that cover your head completely, seal at the neck, and have filtration to give you a couple of minutes to evacuate. The hood portion is Kapton fire retardant material so the dripping flaming plastic from the ceiling will be less likely to set your hair on fire. The acidic fumes will not get to your eyes so you will be better equipped to find the door in the dense smoke.  better to have and not need than to need and not have.&lt;/p&gt;&#xA;&lt;p&gt;From Canada's TSB &lt;a href=&quot;http://www.tsb.gc.ca/eng/rapports-reports/aviation/etudes-studies/sa9501/sa9501.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Safety Study SA9501&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;2.3 The Cabin Environment&lt;/p&gt;&#xA;&lt;p&gt;The presence of fire, smoke, or toxic fumes created evacuation difficulties in 11 of the evacuations reviewed. (This issue is discussed further in Section 3.)&lt;/p&gt;&#xA;&lt;p&gt;In 3 of these 11 evacuations, there were 89 deaths and 25 serious injuries.&lt;/p&gt;&#xA;&lt;p&gt;Visibility was severely restricted or totally obscured in four evacuations where a cabin fire existed.&lt;/p&gt;&#xA;&lt;p&gt;The combination of fire, smoke, and/or toxic fumes was lethal in three of four occurrences where fatalities were incurred.&lt;/p&gt;&#xA;&lt;p&gt;3.0 FIRE, SMOKE, AND TOXIC FUMES&lt;/p&gt;&#xA;&lt;p&gt;Fire, smoke, and/or toxic fumes were present in three of four fatal&#xA;accidents examined in this study and caused serious injuries to many&#xA;of the survivors.&lt;/p&gt;&#xA;&lt;p&gt;The following excerpts from the report of the occurrence at Calgary&#xA;help to illustrate the severe conditions that can exist during an&#xA;evacuation when fire, smoke, and/or toxic fumes are present.&lt;/p&gt;&#xA;&lt;p&gt;Shortly after the evacuation commenced, fire melted windows along the&#xA;left side of the aircraft. When the windows melted through, heat and&#xA;smoke entered the aircraft, and the cabin environment quickly&#xA;deteriorated. Substantial quantities of smoke also entered through the&#xA;right over-wing exit and right rear service door.&lt;/p&gt;&#xA;&lt;p&gt;Those passengers who had been seated beside the windows nearest the&#xA;fire experienced some singeing of hair and clothing. Smoke obscured&#xA;visibility almost totally during the latter stages of the evacuation.&lt;/p&gt;&#xA;&lt;p&gt;Smoke conditions were worse in the aft section of the cabin.&#xA;Passengers who exited via the rear exit reported that they were unable&#xA;to see the exit and were required to follow the person ahead to locate&#xA;it. By the time most had reached this exit, the smoke had lowered to&#xA;about knee height. The bottom portion of the door and the slide were&#xA;all that was visible. The passenger who was the last one to exit via&#xA;the over-wing exit reported he had to drop to his knees to breathe&#xA;fresh air before he was able to reach the exit. Only when he neared&#xA;the exit, did it become visible through the smoke. (A84H0003)&lt;/p&gt;&#xA;&lt;p&gt;The presence of fire, smoke, and/or toxic fumes presented the greatest&#xA;risk to a successful evacuation by restricting visibility, limiting&#xA;communications, reducing the number of available exits, affecting&#xA;passenger behaviour, and decreasing occupants' mental and physical&#xA;capacities. Fire, smoke, and/or toxic fumes were identified as hazards&#xA;in 11 evacuations and were present in three of four fatal occurrences.&lt;/p&gt;&#xA;&lt;p&gt;Thick black smoke severely restricted or totally obscured visibility&#xA;in four occurrences where a cabin fire existed. As a result,&#xA;passengers were unable to see the exits. In Cincinnati, the location&#xA;of two passengers' bodies indicated that, in their attempt to get out&#xA;of the aircraft, they had unknowingly passed an available exit.5&lt;/p&gt;&#xA;&lt;p&gt;In the same occurrence, cabin attendants who were exposed to smoke and&#xA;toxic fumes experienced great difficulty communicating orally. As a&#xA;result, some passengers were unable to hear the emergency briefing.&lt;/p&gt;&#xA;&lt;p&gt;A reduction in the number of available exits was recorded in nine&#xA;occurrences. Fire and smoke also blocked egress in those occurrences&#xA;where breaks in the fuselage were avenues of escape.&lt;/p&gt;&#xA;&lt;p&gt;In three occurrences, it was found that burns and inhalation of smoke&#xA;and toxic fumes limited passengers' mental and physical abilities,&#xA;thereby obstructing or prohibiting their attempts to reach, operate,&#xA;and negotiate emergency exits or egress through breaks in the&#xA;fuselage.&lt;/p&gt;&#xA;&lt;p&gt;Existing Risk Mitigation&lt;/p&gt;&#xA;&lt;p&gt;There are several regulatory provisions which are designed to protect&#xA;aircraft occupants from the risks associated with the presence of&#xA;fire, smoke, and toxic fumes and thus increase the chances for a&#xA;successful evacuation. As well, the industry has developed operating&#xA;procedures to reduce or eliminate the effects of these hazards to crew&#xA;and passengers. In the light of the high risks associated with the&#xA;presence of fire and smoke as evidenced by the Canadian experience,&#xA;the Board examined two areas of risk mitigation related to fire,&#xA;smoke, and toxic fumes, namely protective breathing equipment for both&#xA;crew members and passengers, and fire hardening of aircraft interiors.&#xA;These areas were examined in the context of their potential to limit&#xA;the risks encountered during the evacuation process.&lt;/p&gt;&#xA;&lt;p&gt;3.1 Protective Breathing Equipment&lt;/p&gt;&#xA;&lt;p&gt;She [the flight attendant] saw light grey smoke had filled the&#xA;lavatory from the floor to the ceiling, but she saw no flames. The&#xA;flight attendant closed the door but not before she had become dizzy&#xA;from inhaling the smoke. (A83F0006)&lt;/p&gt;&#xA;&lt;p&gt;Twenty-three passengers died from smoke and toxic fume inhalation as a&#xA;result of an in-flight fire in the rear lavatory of a DC-9. (A83F0006)&#xA;The lavatory was completely filled with smoke that severely restricted&#xA;visibility and impaired breathing. As a result, the cabin attendant&#xA;in-charge was unable to locate the source and exact nature of the fire&#xA;or to fight it effectively. In the investigation report of this&#xA;occurrence, the National Transportation Safety Board (NTSB) stated;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;... had an oxygen bottle with a full-face smoke mask been available&#xA;and used, it might have encouraged and enabled him to take immediate&#xA;and aggressive actions to fight the fire, as set forth in the company&#xA;manual.&amp;quot;6&lt;/p&gt;&#xA;&lt;p&gt;Canadian Industry Practice&lt;/p&gt;&#xA;&lt;p&gt;In addition to the protective breathing equipment (PBE) provided for&#xA;the flight crew, some air carriers provide at least one portable PBE&#xA;unit for crew members who may be required to fight cabin fires on&#xA;non-combi aircraft. Such units are normally located on the flight&#xA;deck. Portable PBE is carried either to fulfil operating requirements,&#xA;as specified in the type certification of some aircraft, or as a&#xA;result of a particular carrier's desire to enhance cabin attendants'&#xA;capabilities to fight fires. The TSB has been advised that some air&#xA;carriers do carry PBE units in the cabin.&lt;/p&gt;&#xA;&lt;p&gt;Regulations in the United States and United Kingdom&lt;/p&gt;&#xA;&lt;p&gt;PBE for flight crews has been a mandatory requirement in the United&#xA;States for over 45 years. In 1987, partly as a result of the DC-9&#xA;occurrence at Cincinnati, the FAA amended Federal Aviation Regulation&#xA;(FAR) 121-337, Protective Breathing Equipment, such that air carriers&#xA;operating transport category aircraft must provide PBE, not only to&#xA;flight crew, but also to other crew members who are responsible for&#xA;fighting fires on board the aircraft. One portable PBE unit is&#xA;required at each hand-held extinguisher station. There is no&#xA;requirement to provide passengers with any form of PBE; indeed, there&#xA;are regulations which specifically prohibit passengers from bringing&#xA;PBE which contains compressed oxygen on board air transport aircraft.&lt;/p&gt;&#xA;&lt;p&gt;In the United Kingdom, PBE is mandatory for both flight and cabin&#xA;crew. Such equipment must be provided for each cabin attendant&#xA;required to be carried under safety regulations and must be readily&#xA;accessible to them at their assigned stations. Supernumerary cabin&#xA;attendants would not figure in the number of PBE units required. PBE&#xA;is not required for passengers.&lt;/p&gt;&#xA;&lt;p&gt;Transport Canada Regulations&lt;/p&gt;&#xA;&lt;p&gt;ANO Series II, No. 9, the Oxygen Equipment Order, stipulates PBE&#xA;requirements for operation of large commercial aircraft. PBE is&#xA;defined in the Order as &amp;quot;... equipment to cover the eyes, nose and&#xA;mouth, or the nose and mouth if accessory equipment is provided to&#xA;protect the eyes, that will protect the wearer from the effects of&#xA;smoke, carbon dioxide or other harmful gases.&amp;quot; In accordance with the&#xA;Order, air carriers operating pressurized aircraft in a commercial air&#xA;service must provide &amp;quot;each flight crew member on duty at his station&#xA;protective breathing equipment.&amp;quot; There is no regulatory requirement to&#xA;provide cabin attendants, other than those working on combi aircraft,&#xA;with PBE.7 Nevertheless, ANO Series VII No. 2, Section 45, &amp;quot;Emergency&#xA;Procedures Training&amp;quot; clearly implies that all cabin attendants are&#xA;expected to fight cabin fire.&lt;/p&gt;&#xA;&lt;p&gt;Similarly, there is no regulatory requirement to provide passengers&#xA;with PBE. Several years ago, Transport Canada participated in an&#xA;international feasibility study addressing the safety benefit of&#xA;providing &amp;quot;smoke hoods&amp;quot;8 for passengers. The results of the study were&#xA;published by the CAA in 1987.9 It was concluded that the number of&#xA;lives saved by smoke hoods each year would be &amp;quot;modest&amp;quot; (179 lives over&#xA;20 years, or approximately 9 lives per year world-wide) and that the&#xA;time required to don the apparatus might increase the time required to&#xA;evacuate an aircraft, thereby causing a greater loss of life.&#xA;Mandatory carriage of smoke hoods as passenger safety equipment was&#xA;not recommended. Neither Transport Canada nor any of the other&#xA;countries who participated in the study (United Kingdom, United States&#xA;and France) have subsequently proposed any regulatory amendments to&#xA;require PBE for passengers.10&lt;/p&gt;&#xA;&lt;p&gt;There remains the question of voluntary carriage of passenger PBE, by&#xA;carriers&lt;/p&gt;&#xA;&lt;p&gt;or by individuals. In accordance with The Transportation of Dangerous&#xA;Goods Act, passengers travelling on Canadian commercial air carriers&#xA;are prohibited from bringing on board passenger transport aircraft&#xA;those smoke hoods which provide oxygen from a cylinder of compressed&#xA;gas. Introduction of oxygen into the cabin environment, other than the&#xA;oxygen found in the emergency overhead oxygen-mask system, which is&#xA;designed for passenger use during an in-flight depressurization, is&#xA;currently viewed as a hazard in the event of an in-flight fire.&#xA;However, small, gaseous oxygen or air cylinders required by passengers&#xA;for medical use are accepted as carry-on baggage or, with the&#xA;operator's approval, as checked baggage. Canada has recently asked&#xA;ICAO to examine, from a dangerous goods perspective, the issue of&#xA;smoke hoods containing a cylinder of compressed gas.&lt;/p&gt;&#xA;&lt;p&gt;Passengers are permitted to carry filtration-type smoke hoods on board&#xA;Canadian aircraft but current filtration-type smoke hoods would not be&#xA;as effective as smoke hoods which have a self-contained source of&#xA;breathable oxygen.&lt;/p&gt;&#xA;&lt;p&gt;Recommendations&lt;/p&gt;&#xA;&lt;p&gt;In the context of the actual evacuation process, there is no direct&#xA;evidence that a lack of PBE for cabin crew resulted in fatalities or&#xA;injuries during evacuations. Yet, there is a paradox in that cabin&#xA;attendants are expected to fight cabin fires, but, in many cases, they&#xA;are not provided with PBE in the aircraft cabin. Ready access to&#xA;portable PBE could improve their ability to fight fires and have the&#xA;effect of reducing the risks faced by occupants during an evacuation.&#xA;Therefore, the Board recommends that:&lt;/p&gt;&#xA;&lt;p&gt;The Department of Transport require that sufficient portable&#xA;protective breathing equipment units with full-face masks be carried&#xA;in the passenger cabins of transport aircraft for cabin crew. A95-01&lt;/p&gt;&#xA;&lt;p&gt;In the light of the number of fatalities that occur when fire, smoke,&#xA;and/or toxic fumes are present, the Board believes that further&#xA;research is required to determine whether passengers should be given&#xA;the opportunity to carry appropriate protective breathing equipment.&#xA;Accordingly, the Board recommends that:&lt;/p&gt;&#xA;&lt;p&gt;The Department of Transport re-evaluate research regarding protective&#xA;breathing equipment (PBE) for passengers with a view to determining&#xA;the feasibility of the carriage of appropriate protective breathing&#xA;equipment, on a voluntary basis. A95-02&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9974" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-07-21T21:37:40.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19371" PostTypeId="2" ParentId="19369" CreationDate="2015-08-27T02:09:05.983" Score="8" Body="&lt;p&gt;In general, they don't. U.S. airlines generally allow you to use your phones as soon as the plane lands.&lt;/p&gt;&#xA;&lt;h3&gt;Southwest:&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Effective today, Southwest Customers with cell phones onboard may begin using them after the flight attendant gives permission to do so upon landing at the destination and taxi to the airport gate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://swamedia.com/releases/Southwest-Relaxes-Cell-Phone-Use-Policy-Airline-Adds-Convenience-of-Cell-Phone-Use-During-Taxi-to-Gate-for-Customers&quot; rel=&quot;noreferrer&quot;&gt;Southwest Press Release from Sept 2, 2003&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;Delta:&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Use of cellular devices prior to takeoff is not allowed per Delta policy so that flight attendants may properly prepare the cabin for departure and conduct safety demonstrations uninterrupted. Cellular devices may be used upon landing as instructed by the cabin crew.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://skift.com/2013/10/31/everything-you-need-to-know-about-using-devices-on-u-s-airlines/&quot; rel=&quot;noreferrer&quot;&gt;Everything You Need to Know About Using Devices on U.S. Airlines&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Perhaps of interest, the rule against using cell phone during flight in the U.S. &lt;strong&gt;is not&lt;/strong&gt; an FAA Federal Aviation Regulation. It is instead an FCC (Federal Communications Commission) regulation designed to prevent interference to the cell network as a result of thousands of phones flying around at 600 mph hitting hundreds of cell stations at once. In general, the FCC acknowledges that this rule is outdated and that this is no longer an issue for the current cell network. As such, &lt;a href=&quot;https://www.fcc.gov/guides/wireless-devices-airplanes&quot; rel=&quot;noreferrer&quot;&gt;the FCC has issued a proposal to remove this regulation&lt;/a&gt;. However, some airlines (including Delta and Southwest) have &lt;a href=&quot;http://aviationblog.dallasnews.com/2013/12/no-phones-on-our-planes-say-two-airline-ceos.html/&quot; rel=&quot;noreferrer&quot;&gt;publicly stated that they will continue to not allow cell phone use for voice calls during flight even if it is legal&lt;/a&gt;, as the majority of their customers have indicated that they don't want to listen to their neighbors chatting on a cell phone for hours on end.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Delta will not allow cellular calls or internet-based voice communications onboard Delta or Delta Connection flights. Our customer research and direct feedback tell us that our frequent flyers believe voice calls in the cabin would be a disruption to the travel experience.&lt;/p&gt;&#xA;&lt;p&gt;In fact, a clear majority of customers who responded to a 2012 survey said they felt the ability to make voice calls onboard would detract from – not enhance – their experience. Delta employees, particularly our in-flight crews, have told us definitively that they are not in favor of voice calls onboard.&lt;/p&gt;&#xA;&lt;p&gt;-&lt;a href=&quot;http://aviationblog.dallasnews.com/2013/12/no-phones-on-our-planes-say-two-airline-ceos.html/&quot; rel=&quot;noreferrer&quot;&gt;Delta CEO Richard Anderson&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-08-27T02:19:15.433" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19376" PostTypeId="2" ParentId="6285" CreationDate="2015-08-27T03:10:26.330" Score="0" Body="&lt;p&gt;Part of the reason for using an anhedral wing on cargo aircraft is that at speed, the wings lift and are straight out. If you look at the B-52, the wings are so long that even though they need the outriggers when on the ground, the wings flare up while in flight.&lt;/p&gt;&#xA;" OwnerUserId="9977" LastActivityDate="2015-08-27T03:10:26.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19377" PostTypeId="2" ParentId="19365" CreationDate="2015-08-27T03:11:39.893" Score="0" Body="&lt;p&gt;Very, very few. We (not just the West, but most of the world) all follow ICAO document 4444.    &lt;/p&gt;&#xA;" OwnerUserId="9957" LastActivityDate="2015-08-27T03:11:39.893" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19378" PostTypeId="2" ParentId="19365" CreationDate="2015-08-27T03:21:13.370" Score="1" Body="&lt;p&gt;One of the big differences between regions is how aircraft operators pay for the service. In the US, the FAA is funded by taxpayers and fuel levies. In New Zealand (for example), aircraft operators are billed for use of air traffic control services. I don't know what the billing situation is in Europe.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-08-27T03:21:13.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19379" PostTypeId="2" ParentId="19369" CreationDate="2015-08-27T05:30:48.473" Score="-1" Body="&lt;p&gt;Though all systems are gone through series of electro magnetic Tests in the Lab. The mobile phone signal may contribute enough electro magnetic interference in the real world. Due to this electro magnetic interference the systems may start behaving differently and erroneously. Take off and Landing are the crucial stages of flight phases, it is always better to avoid the chances of taking risks. If 1 mobile phone can produce this, you could just imagine about the all passengers turning on their mobile phones and contribute the interference. &lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-08-27T05:30:48.473" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19381" PostTypeId="2" ParentId="19333" CreationDate="2015-08-27T06:14:28.103" Score="1" Body="&lt;p&gt;Even military operations carried for long mission would carry the dried food items which can be stored for long time, light in weight and heavy rich nutrients/calories. B-52 Bomber might carry these items which are approved by Authority and it's government.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-08-27T06:14:28.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19382" PostTypeId="2" ParentId="19368" CreationDate="2015-08-27T07:31:28.687" Score="6" Body="&lt;p&gt;It is possible, but just not that useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Controllability&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to maximize the moment incuded by the rudder (or keep the rudder as small as possible to provide this moment), you want to place the rudder as far (in longitudinal sense) from the center of gravity. This increases the moment induced, and thus the effectiveness of the rudder. In a normal airliner, you'll have a tube with wings in the middle, and thus the most aft part to place the rudder is at the end of the tube. On the aircraft in your picture, the most aft part is the wing tip, so it makes sense to put the rudder there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Structural reasons&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you place the rudder at the end, this will mean there will be substantial forces induced at the tip of the wing if you use the rudder. This means that you will have a substantial bending moment added to the wing, making it much heavier.&#xA;This is further discussed in &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;Winglet vs span extension&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-27T10:59:16.583" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19383" PostTypeId="2" ParentId="7639" CreationDate="2015-08-27T08:31:59.923" Score="10" Body="&lt;p&gt;I've found some useful research here: &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930085000.pdf&quot; rel=&quot;noreferrer&quot;&gt;E.C. Polhamus. Some factors affecting the variation of pitching moment with sideslip of&#xA;aircraft configurations. Technical report, NACA T.N. 4016, 1958.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image shows the situation for high angles of $\beta$:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At large angles of sideslip with swept horizontal&#xA;  tails, the loading will probably not be antisymmetrical mainly because&#xA;  of the difference in lift effectiveness of the leading and trailing portions&#xA;  of the horizontal tail caused by the difference in their effective&#xA;  sweep angles. This would result in a net lift induced on the horizontal&#xA;  tail which is a function of sideslip and tail height. This possible&#xA;  effect of tail height is illustrated in sketch 9 for large positive sideslip&#xA;  angles: &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KGVdF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KGVdF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zrtQf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zrtQf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interesting to see is that the model has no wings, so we can rule out any causes related to wings, in case people were thinking in this direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I putsome more thought into it, and I drew these diagrams, which helped me understand the things being said in the paper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blue pluses and minuses are the resulting velocities caused by the horizontal velocity as a function of the sideslip ($V_{\beta}$).&#xA;The red distributions are the forces on the elevator as consequence of this $V_{\beta}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This component creates an increased velocity over the left side of the rudder, and a decreased velocity over the right side of the rudder.&#xA;If there's no sweep, the effects are equally strong, and no effect on the lift is present (denoted by the top two images)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if there's sweep, the effect on the left side is less strong, whereas it is stronger on the right side (indicated by the two tails in the bottom row).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a T-tail, this stronger influence is acting on the lower side of the tail. As it is a minus (meaning a relative reduction in velocity), it will lead to a reduction in suction on the lower side, or an upward force, causing a pitch down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a normal tail, the minus will act over the upper surface. It causes a deceleration of the flow over the elevator, thereby reducing the lift it generates. This causes a pitch up movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/18jx4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/18jx4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-09-03T12:02:56.740" LastActivityDate="2015-09-03T12:02:56.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19384" PostTypeId="1" CreationDate="2015-08-27T09:12:04.367" Score="6" ViewCount="645" Body="&lt;p&gt;For &lt;a href=&quot;http://www.cenipa.aer.mil.br/cenipa/paginas/relatorios/pdf/3054ing.pdf&quot; rel=&quot;nofollow&quot;&gt;the accident&lt;/a&gt;, why did the aircraft veer off the runway near the end of the runway, instead of the moment it touched down (where the left engine went into reverse thrust and the right engine powered up to climb throttle)?&#xA;The aircraft managed to maintain a (relatively) straight path for most of the runway length. I thought asymmetrical thrust that significant would immediately send it off course&lt;/p&gt;&#xA;" OwnerUserId="9983" LastEditorUserId="19" LastEditDate="2016-11-11T13:31:37.380" LastActivityDate="2016-11-11T13:31:37.380" Title="Why did the crashed TAM Airlines Flight 3054 veer off the runway only near the end?" Tags="&lt;landing&gt;&lt;accidents&gt;&lt;engine-failure&gt;&lt;thrust-reverser&gt;&lt;tam3054-accident&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19385" PostTypeId="2" ParentId="19361" CreationDate="2015-08-27T09:16:52.043" Score="27" Body="&lt;p&gt;In the early days, it really looks as if people hadn't really worked out what worked best&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iKgmR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iKgmR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Horatio_Frederick_Phillips&quot; rel=&quot;noreferrer&quot;&gt;Horatio Frederick Phillips, 1904 Multiplane. Longest flight 50 feet (15 metres)&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3VBzl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3VBzl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Caproni_Ca.60&quot; rel=&quot;noreferrer&quot;&gt;Gianni Caproni, Ca.60. 1921. Crashed on second flight&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wire-braced box girder structure can probably provide better strength and rigidity than a single, and much longer, wooden spar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An advantage of multiple wings is that you can have shorter wings, and this can improve maneuverability in combat&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8uTUS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8uTUS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Fokker_Dr.I&quot; rel=&quot;noreferrer&quot;&gt;Fokker triplane. 1917&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe a better question is why people opted for only two wings when they could have had twenty?&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2019-09-17T14:36:15.640" LastActivityDate="2019-09-17T14:36:15.640" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="19386" PostTypeId="1" CreationDate="2015-08-27T09:59:23.307" Score="9" ViewCount="239" Body="&lt;p&gt;I'm particularly interested in Approach procedures, but I guess it applies for RNAV procedures in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On one side, the national Air Navigation Service Provider (ANSP) is responsible for the design of the procedure. The procedure charts are usually available as PDF files through AIP website (e.g. the terminal procedures available at &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/&quot;&gt;FAA&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other side, the RNAV procedure is coded in binary format inside aircraft's FMS. The airborne databases that can be directly loaded to the FMS are provided by external companies (Jeppesen, Lufthansa, Navigraph).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens between those two points is kind of puzzling for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know of ARINC-424 standard for aircraft navigation data that is used for &quot;preparation and transmission of data&quot;. Then there is AIRAC cycle which as I understand provides fixed dates for any changes to become effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Who takes responsibility that the database being sold to airline or any user reflects the original procedure published by ANSP?&lt;/li&gt;&#xA;&lt;li&gt;How does the coding process look like. Is it based on PDF charts or there is another exchange format available (e.g. AIXM)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9982" LastEditorUserId="19" LastEditDate="2017-08-14T08:05:37.247" LastActivityDate="2017-08-14T08:05:37.247" Title="What happens with RNAV procedures on the way from AIP publication to FMS database?" Tags="&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19388" PostTypeId="1" AcceptedAnswerId="19399" CreationDate="2015-08-27T11:00:14.377" Score="28" ViewCount="136312" Body="&lt;p&gt;I have just started learning some aerospace concepts, and I am not able to understand the difference between the three terms &lt;a href=&quot;https://en.wikipedia.org/wiki/Center_of_pressure_%28fluid_mechanics%29&quot;&gt;centre of pressure&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerodynamic_center&quot;&gt;aerodynamic centre&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Longitudinal_static_stability#Neutral_point&quot;&gt;neutral point&lt;/a&gt;. What are their functional differences?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would be an example that distinguishes these three?&lt;/p&gt;&#xA;" OwnerUserId="9986" LastEditorUserId="849" LastEditDate="2015-08-27T18:43:45.157" LastActivityDate="2019-04-10T07:41:02.503" Title="What is the difference between centre of pressure, aerodynamic centre and neutral point?" Tags="&lt;aerodynamics&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="19389" PostTypeId="2" ParentId="19368" CreationDate="2015-08-27T11:16:24.320" Score="10" Body="&lt;p&gt;The purpose of the rudder is to control the heading of the aircraft. It turns the aircraft by creating an aerodynamic moment about the vertical axis of the aircraft. The moment is product of the aerodynamic force and the arm. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/S9v16.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S9v16.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;image: NASA&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic force is the the side force on the rudder, the arm is the distance between the rudder and the centre of gravity of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the rudder would be on the winglets, the side force of the rudder would act at a short distance behind the centre of gravity, reducing the effectiveness very much. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be possible the have airbrakes on the winglets / wingtips and use differential braking to create the rotating moment. This is done for example on the B2 which doesn't have a vertical stabilizer. The added complexity and weight increase makes it an unattractive option for conventional aircraft.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-08-27T11:16:24.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19390" PostTypeId="2" ParentId="19295" CreationDate="2015-08-27T11:21:16.177" Score="1" Body="&lt;p&gt;In modern aircraft, this would happen (FMC intern uses these on priority basis 1. GPS 2. DME 3. VOR 4. IRS). In old aircraft their order remains same without FMS in place.&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_management_system#Position_determination&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Flight_management_system#Position_determination&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="9966" LastEditDate="2015-08-27T11:52:29.860" LastActivityDate="2015-08-27T11:52:29.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19391" PostTypeId="1" AcceptedAnswerId="19432" CreationDate="2015-08-27T11:29:49.850" Score="15" ViewCount="4313" Body="&lt;p&gt;In the 80s and 90s, regulation increased to prohibit smoking in passenger planes. Was smoking ever identified as the cause for serious accident in flight (for example the cabin caught fire as a result of a stray cigarette on the carpeting or seats)?&lt;/p&gt;&#xA;" OwnerUserId="9987" LastActivityDate="2017-12-11T21:17:00.093" Title="Was there ever an accident from in-flight smoking?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19394" PostTypeId="2" ParentId="19388" CreationDate="2015-08-27T12:19:43.700" Score="10" Body="&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/cp.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Center of pressure&lt;/a&gt;:&lt;/strong&gt; the net force of air on a body/surface/wing. The center of pressure changes as an aircraft maneuvers because different parts of the aircraft stick into the airflow as the angle of attack changes. Notice how the center of pressure moves forward as the angle of attack increases (the airflow is right-to-left):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TJIpo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TJIpo.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://images.prepware.com/ASA-PPT-11/PPT-1-19.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;prepware.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/ac.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerodynamic center&lt;/a&gt;:&lt;/strong&gt; the location at which the moment does not change regardless of the angle of attack. Wings tend to produce a rotational force due to the way they push air around, and this is the location at which the rotational force stays constant at any angle of attack. It is often easier to consider the aerodynamic center for where you want to place your wings and mass because its location is constant, unlike the center of pressure. For now, think of M&lt;sub&gt;trim&lt;/sub&gt; as equivalent to the rotational force the elevators must impart in order to achieve level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kl1v5.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kl1v5.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.charlesriverrc.org/articles/asfwpp/lelke_fig9.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;charlesriverrc.org&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://people.rit.edu/pnveme/EMEM682n/StaticStab/Neutral_point.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Neutral Point&lt;/a&gt;:&lt;/strong&gt; the position of center of mass where the aircraft would be &lt;a href=&quot;http://qph.is.quoracdn.net/main-qimg-a9ed8f26b0eda2feb3935b8e85c5d10f?convert_to_webp=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;neutrally stable&lt;/a&gt;. If you put your center of mass behind (aft) of this point, you will get an unstable aircraft that will increasingly turn with any maneuver the pilot makes. At low speeds, this may be tolerable, but computers are needed to fly unstable aircraft at higher speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R7Q8o.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R7Q8o.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://adamone.rchomepage.com/np.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;rchomepage.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;tl;dr:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;CoP&lt;/em&gt; = where the wings push&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;AC&lt;/em&gt; = where the wings rotate&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;NP&lt;/em&gt; = where the center of mass should be to make an aircraft that does not tend to pitch up or down&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="8282" LastEditDate="2019-04-10T07:41:02.503" LastActivityDate="2019-04-10T07:41:02.503" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="19395" PostTypeId="5" CreationDate="2015-08-27T12:41:59.127" Score="0" Body="&lt;p&gt;The &lt;em&gt;Airbus A330&lt;/em&gt; is a widebody twinjet airliner produced by Airbus since 1992, which entered commercial service in 1994; however, its development process (along with that of its four-engined sister model, the &lt;a href=&quot;/questions/tagged/airbus-a340&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a340&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a340&lt;/a&gt;) dates back to the mid-1970s, when it was first conceived of as a larger, longer-range derivative of the earlier &lt;a href=&quot;/questions/tagged/airbus-a300&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a300&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a300&lt;/a&gt;.  Competing twinjets include the &lt;a href=&quot;/questions/tagged/boeing-767&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-767&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-767&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt;, and &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are four major civilian versions of the A330 (two &quot;Current Engine Option&quot;, or &quot;ceo&quot;, and two &quot;New Engine Option&quot;, or &quot;neo&quot;), plus one military version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The civilian versions, ordered by date of introduction into service, are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A330ceo (Current Engine Option) versions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;[These versions use General Electric CF6-80E, Pratt &amp;amp; Whitney PW4000, or Rolls-Royce Trent 700 engines.]&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;strong&gt;A330-300&lt;/strong&gt; is the original version, which entered service in January 1994; it has a range of up to 11,750 km (6,350 nmi), and typically carries from 277 to 335 passengers (with an absolute upper limit of 440 in an 'economy-only' configuration).  As of December 2019, 770 A330-300s have been delivered, with a further 15 on order.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;A330-200&lt;/strong&gt; is a shortened version (typical capacity 253 passengers) with a range of up to 13,400 km (7,240 nmi); in addition to the shortened fuselage (which requires a larger &lt;a href=&quot;/questions/tagged/vertical-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vertical-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;vertical-stabilizer&lt;/a&gt;), it achieves this longer range by adding a center fuel tank and strengthening the wings to allow them to carry the increased fuel load.  The A330-200 entered service in 1998; 640 have been delivered, with 20 more orders pending.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The A330-200 also has a dedicated &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt; variant, the &lt;strong&gt;A330-200F&lt;/strong&gt; (&quot;F&quot; for &quot;Freighter&quot;).  The main difference between the vanilla -200 and the -200F is that the latter's nose &lt;a href=&quot;/questions/tagged/landing-gear&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;landing-gear&amp;#39;&quot; rel=&quot;tag&quot;&gt;landing-gear&lt;/a&gt; is mounted on a distinctive bulge on the aircraft's lower front fuselage; this was done to make loading and unloading of cargo easier, as a vanilla A330 sits at a slight nose-down angle when on the ground, and the -200F's bulge raises the aircraft's nose just enough for the floor of the main cargo deck to be level rather than slanted.  38 have been delivered so far, with three still to go.  Airbus also offers cargo conversions of passenger A330s (currently restricted to the two ceo models); these aircraft, designated the &lt;strong&gt;A330-300P2F&lt;/strong&gt; and &lt;strong&gt;A330-200P2F&lt;/strong&gt; (&lt;strong&gt;P&lt;/strong&gt;assenger-&lt;strong&gt;to&lt;/strong&gt;-&lt;strong&gt;F&lt;/strong&gt;reight[er]), do &lt;em&gt;not&lt;/em&gt; have the nose bulge of the -200F, the slanted floor instead being dealt with by an improved cargo-loading system.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A330neo (New Engine Option) versions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;[These versions use Rolls-Royce Trent 7000 engines.]&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;strong&gt;A330-900&lt;/strong&gt; is intended to replace the A330-300.  It shares the fuselage structure of the -300, but has new, more efficient engines and tweaked wing aerodynamics, which combine to give it a lower fuel consumption and greater range (up to 13,300 km [7200 nmi]) than the -300; the -900 also has a new cabin interior, intended to make flying on the A330 more pleasant for the passengers.  The A330-900 first flew in October 2017; as of December 2019, 44 have been delivered to customers, and 279 ordered but not yet delivered.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;A330-800&lt;/strong&gt; is intended to replace the A330-200.  It features the same changes as the A330-900, but applied to the A330-200 rather than the A330-300; the combination of these improvements with the -200's already-long range gives the -800 the longest range of any A330 yet, up to 15,100 km (8,150 nmi).  The A330-800 first flew in November 2018, but has received a total of only 14 orders (and no deliveries thus far), being as expensive to operate as the A330-900 while carrying fewer passengers, and with its market niche eroded by the -900's increased range.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The military version is the &lt;strong&gt;A330 MRTT (Multi-Role Tanker/Transport)&lt;/strong&gt;, which, as the name indicates, serves both as a &lt;a href=&quot;/questions/tagged/tanker&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tanker&amp;#39;&quot; rel=&quot;tag&quot;&gt;tanker&lt;/a&gt; aircraft for &lt;a href=&quot;/questions/tagged/mid-air-refueling&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;mid-air-refueling&amp;#39;&quot; rel=&quot;tag&quot;&gt;mid-air-refueling&lt;/a&gt; of military aircraft and as a troop and/or materiel transport.  Although mostly based on the A330-200, it uses the wings of the A340, which are stronger than those of the civilian A330; its engines are mounted on the wing's inboard pylons, while the outboard pylons (those that would carry the #1 and #4 engines on an A340) hold pods for refueling &lt;a href=&quot;/questions/tagged/fighter&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fighter&amp;#39;&quot; rel=&quot;tag&quot;&gt;fighter&lt;/a&gt; aircraft.  41 A330 MRTTs have been delivered so far, with another 19 firm orders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A330 is the base for the second-generation version of the &lt;a href=&quot;/questions/tagged/airbus-beluga&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-beluga&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-beluga&lt;/a&gt; (known as the &lt;em&gt;Beluga XL&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see Wikipedia's articles on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A330 in general (but primarily the ceo variants)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330neo&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A330neo&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330_MRTT&quot; rel=&quot;nofollow noreferrer&quot;&gt;the A330 MRTT&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="22726" LastEditDate="2020-01-18T06:16:29.323" LastActivityDate="2020-01-18T06:16:29.323" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19396" PostTypeId="4" CreationDate="2015-08-27T12:41:59.127" Score="0" Body="A medium- to long-range twin-engine widebody jetliner made by Airbus since 1992." OwnerUserId="3775" LastEditorUserId="22726" LastEditDate="2019-01-10T06:20:23.897" LastActivityDate="2019-01-10T06:20:23.897" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19397" PostTypeId="1" AcceptedAnswerId="19400" CreationDate="2015-08-27T13:12:43.640" Score="4" ViewCount="168" Body="&lt;p&gt;Is it possible for three-letter ICAO airline designators to get reassigned?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, I'm trying to find out if &lt;code&gt;BKL&lt;/code&gt; was previously used for &lt;a href=&quot;https://en.wikipedia.org/wiki/Baikal_Airlines&quot; rel=&quot;nofollow&quot;&gt;Baikal Airlines&lt;/a&gt; (ceased to exist in 2001) and reassigned to &lt;a href=&quot;https://en.wikipedia.org/wiki/Barkol_Airlines&quot; rel=&quot;nofollow&quot;&gt;Barkol Airlines&lt;/a&gt; (founded 1996, although it's unclear when they received their ICAO code).&lt;/p&gt;&#xA;" OwnerUserId="3393" LastActivityDate="2015-08-27T15:17:06.417" Title="Can ICAO airline designators be reassigned to a new airline?" Tags="&lt;airlines&gt;&lt;icao&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19398" PostTypeId="1" CreationDate="2015-08-27T13:40:59.470" Score="8" ViewCount="323" Body="&lt;p&gt;I rode a smaller twin-tail-engined jetliner for a few short hops last month, and I noticed that their airport approaches are much rougher than the widebody airliners I am used to. I believe that it was an &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/1/15/Iberia.md-88.ec-foz.arp.jpg/300px-Iberia.md-88.ec-foz.arp.jpg&quot;&gt;MD-80&lt;/a&gt; with United Airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As soon as the pilot began the descent, it seems like the he/she was going wild with the throttle; the engines would appear to idle for 10 seconds, then suddenly and audibly power to full for another 10 seconds, and the cycle would repeat until we were right above the runway. I know that this was not crew specific because I took the commercial flight on 6 different occasions on three different routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt; Why did the pilots increase and decrease the throttle so rapidly and so many times on descent to the runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;edit: Terrain: flat, Atlanta area; Meteorological conditions: heavy cumulus, twice during the night and the other four during dusk, light to moderate rain under and in the clouds. The clouds had no breaks and often had a strange formation where in some areas they would rise much higher than others. Imagine a series of mountains and valleys with several&lt;sup&gt;?&lt;/sup&gt; miles of distance between cloud peaks and cloud dips.&lt;/p&gt;&#xA;" OwnerUserId="9875" LastEditorUserId="19" LastEditDate="2016-08-05T16:26:48.840" LastActivityDate="2016-09-07T17:01:35.617" Title="What could cause a rear twin-jet's throttle to oscillate on descent?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;approach&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19399" PostTypeId="2" ParentId="19388" CreationDate="2015-08-27T14:05:39.570" Score="30" Body="&lt;p&gt;Any body moving in a fluid experiences pressure forces over its surface. The concepts of center of pressure, aerodynamics center and neutral point are useful in understanding the effects of these forces. Let's take an airfoil moving in air with subsonic flow attached to the body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Center of Pressure&lt;/strong&gt; The center of pressure is the point where the total sum of a pressure field acts on a body. In aerospace, this is the point on the airfoil (or wing) where the resultant vector (of lift and drag) acts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/12uJP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/12uJP.jpg&quot; alt=&quot;Center of Pressure&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: avstop.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the airfoil angle of attack changes, the pressure field changes. Due to this, the &lt;em&gt;center of pressure changes with variation in the angle of attack&lt;/em&gt;. In the airplane's normal range of flight attitudes, if the angle of attack is increased, the center of pressure moves forward; and if decreased, it moves rearward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nt19h.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nt19h.jpg&quot; alt=&quot;Movement of Center of Pressure&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.flightlearnings.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the center of gravity (the point where the weight of the body acts) is fixed, this movement of center of pressure affects the  stability of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aerodynamic Center&lt;/strong&gt; The resultant (or the pressure forces) also cause a moment on the airfoil. As the angle of attack increases, the pitching moment at a point (for example, the center of gravity) also changes. However, the pitching moment remains constant at a particular point, which is called the aerodynamic center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/09cSD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/09cSD.jpg&quot; alt=&quot;Aerodynamic Center&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.theairlinepilots.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For symmetric airfoils in subsonic flight the aerodynamic center is located approximately 25% of the chord from the leading edge of the airfoil. This point is described as the quarter-chord point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus the &lt;em&gt;aerodynamic center does not change with variation in angle of attack&lt;/em&gt;. Due to this, the aerodynamic center, rather than the center of pressure is used in the analysis of longitudinal stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Neutral Point&lt;/strong&gt; Consider the whole aircraft. The lift of the wing acting through the center of pressure is in front of the center of gravity of the aircraft. This causes a destabilizing motion (increase in lift to increase in angle of attack causes a nose up moment, further increasing angle of attack). This is counteracted by the moment produced by the lift of the horizontal stabilizer (which is a small wing), acting behind the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q9B8d.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q9B8d.png&quot; alt=&quot;Forces on aircraft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:AirStability.svg#/media/File:AirStability.svg&quot; rel=&quot;noreferrer&quot;&gt;AirStability&lt;/a&gt;&quot; by User_A1 - SVG derivative of Public Domain work by G J Vigurs. Licensed under GFDL via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the center of gravity is moved forward, the stability of the aircraft increases (as the main wing lift arm is reduced) and the aircraft is &lt;em&gt;statically stable&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BBdGx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BBdGx.jpg&quot; alt=&quot;Statically Stable&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: quest.arc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the center of gravity is moved aft, the main wing lift moment arm increases and the aircraft stability decreases. The aircraft is said to be &lt;em&gt;statically unstable&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cXHMM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cXHMM.jpg&quot; alt=&quot;Statically Unstable&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: quest.arc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft is stable when center of gravity is in the nose and unstable when center of gravity is in the tail, there is a position in the middle where the aircraft is neither stable nor unstable i.e the stability is neutral. This point is called the neutral point. The neutral point is fixed for a particular aerodynamic configuration of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/um1IQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/um1IQ.jpg&quot; alt=&quot;Neutrally Stable&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: quest.arc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Center of pressure of an aircraft is the point where the Lift acts. &lt;/li&gt;&#xA;&lt;li&gt;Aerodynamic center is the point in the wing where the pitching moments are constant.&lt;/li&gt;&#xA;&lt;li&gt;The neutral point is where the center of gravity of the aircraft is neutrally stable &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="31244" LastEditDate="2018-12-31T05:21:08.800" LastActivityDate="2018-12-31T05:21:08.800" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="19400" PostTypeId="2" ParentId="19397" CreationDate="2015-08-27T14:22:09.700" Score="7" Body="&lt;p&gt;Yes. As per &lt;a href=&quot;http://www4.icao.int/3LD/Home/Rules&quot;&gt;rules&lt;/a&gt; ICAO can reassign the three letter airline designators after a period of 60 days. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When a designator is no longer required, ICAO should be informed immediately. Any such designator so released will not be reassigned until a period of at least 60 days has elapsed. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The designator BKL was used by Baikal Airlines and is currently used by Aircompany Barcol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is the airline designator WOW, which was used by &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Southwest&quot;&gt;Air Southwest&lt;/a&gt;  and is currently used by &lt;a href=&quot;http://wowair.com/&quot;&gt;WOW air&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-08-27T15:17:06.417" LastActivityDate="2015-08-27T15:17:06.417" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19401" PostTypeId="2" ParentId="19324" CreationDate="2015-08-27T14:25:19.150" Score="16" Body="&lt;p&gt;The long length of an airliner fuselage ensures turbulent flow at the station of the cabin windows, so their only contribution to friction drag are the gaps between metal and polycarbonate. The &lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956?s=2%7C0.0519#16956&quot;&gt;transition from a laminar to a turbulent boundary layer&lt;/a&gt; happens before the windows start. In Sighard Hoerner's classic Fluid Dynamic Drag we find in Chapter V these figures on the drag of surface imperfections:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KspPJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KspPJ.png&quot; alt=&quot;Hoerner Fluid Dynamic Drag Chapter V Fig. 22&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The size of the gaps and the dynamic pressure at their location drives their drag contribution. Let's assume the windows are 0.4&amp;nbsp;m high, the grooves 2.5&amp;nbsp;mm (0.1&quot;) wide and shallow enough to have a drag coefficient of 0.008. Let's further assume we talk of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747#747-200&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-200&lt;/a&gt; with 100 such windows per side and restrict the drag calculation to the crossflow over the vertical part of the gaps. The full opening area of all gaps is $2\cdot100\cdot2\cdot0.4\cdot0.0025$ = 0.4&amp;nbsp;m² or 0.078% of the reference area of the 747. Wikipedia gives the parasitic drag coefficient of the Boeing 747 as 0.022, so the windows contribute &lt;strong&gt;one threethousandfivehundreth&lt;/strong&gt; of that drag. Negligible, in other words.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there is another source of drag: The windows are &lt;a href=&quot;https://aviation.stackexchange.com/questions/12359/what-is-the-weight-saving-of-windowless-fuselage-for-cargo-aircraft/12362#12362&quot;&gt;heavier than the metal which they replace&lt;/a&gt;, and to carry them around will increase induced drag. If we again assume 200 windows for a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747#747-200&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-200&lt;/a&gt; at 7 kg each (these are from pre-polycarbonate times!), they weigh a total of 1.4 tons. This is 0.8% of its empty mass and &lt;a href=&quot;http://www.icao.int/Meetings/STA10/Documents/Sta10_Wp005_en.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;equivalent to 12-14 passengers&lt;/a&gt;. To find the impact of this mass on a long-range flight over 6000 NM, we can use the &lt;a href=&quot;https://en.wikipedia.org/wiki/Range_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Breguet equation&lt;/a&gt;; once with and once without the 1.4&amp;nbsp;tons of additional mass. The empty mass of the Boeing 747-200 plus 50&amp;nbsp;tons of payload is 228,100&amp;nbsp;kg, its L/D is 16, the specific fuel burn of its JT-9D-7 engines is $b_f$ = 0.0000184&amp;nbsp;kg/Ns and the cruise speed is Mach&amp;nbsp;0.84, which equates to $v$ = 250&amp;nbsp;m/s in FL 350:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$m_1 = m_2\cdot e^{\frac{R\cdot g\cdot b_f}{v\cdot L/D}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we use $R$&amp;nbsp;=&amp;nbsp;11,112 km and run this once with landing masses $m_2$&amp;nbsp;=&amp;nbsp;228,100 kg and again with $m_2$&amp;nbsp;=&amp;nbsp;226,700 kg, the difference in $m_1$ is bigger by a factor of 1.65 (the take-off masses $m_1$ are 376,584&amp;nbsp;kg with and 374,237&amp;nbsp;kg without windows), so carrying the windows around costs the Boeing 747-200 911&amp;nbsp;kg of fuel or 0.61% of the total fuel mass per flight. This is &lt;strong&gt;one onehundredsixtythird&lt;/strong&gt; of the total drag - still not much, but &lt;strong&gt;fourty times as much&lt;/strong&gt; as the absolute contribution of the windows to friction drag (if we assume that the 747 flies at the &lt;a href=&quot;https://aviation.stackexchange.com/questions/4967/how-can-you-find-the-best-altitude-for-range-or-speed/4970#4970&quot;&gt;polar point for optimum range&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This explains why &lt;a href=&quot;http://www.nycaviation.com/2015/02/anatomy-freighter/#.Vd-DVbRDJC4&quot; rel=&quot;nofollow noreferrer&quot;&gt;conversions of airliners to freighters&lt;/a&gt; almost always replace the windows by metal plates but don't care that much about the gaps they leave. In the case of the 747 pictured below they are certainly big enough to be visible from afar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g7juj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g7juj.jpg&quot; alt=&quot;A Japan Airlines Boeing 747 passenger-to-freighter conversion featuring aluminum window plugs. (Photo credit: Flickr)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Japan Airlines Boeing 747 passenger-to-freighter conversion featuring aluminum window plugs. (Photo credit: Flickr)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-12-04T15:55:52.957" LastActivityDate="2017-12-04T15:55:52.957" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19402" PostTypeId="2" ParentId="17474" CreationDate="2015-08-27T14:36:45.263" Score="0" Body="&lt;p&gt;The empennage height is the distance from the ground to the top of the tailfin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It determines the minimum clearance the aircraft needs to taxi under an obstruction.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-08-27T14:36:45.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19403" PostTypeId="1" CreationDate="2015-08-27T14:43:57.577" Score="6" ViewCount="2080" Body="&lt;p&gt;To obtain a private pilot certificate in the US you need a minimum of 40 flying hours. Is there a minimum of ground school hours? Or is it just however long you need to pass the test?&lt;/p&gt;&#xA;" OwnerUserId="9990" LastEditorUserId="1696" LastEditDate="2015-08-27T14:56:11.283" LastActivityDate="2015-08-27T15:04:40.487" Title="Does a private pilot certificate require a certain number of ground school hours?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19404" PostTypeId="2" ParentId="19403" CreationDate="2015-08-27T14:47:10.473" Score="5" Body="&lt;p&gt;For training conducted under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61&lt;/a&gt; there is no requirement for groundschool.  The only requirements are that you take and pass written tests, but how you prepare for them (formal groundschool, self-study, etc) is completely up to you.  You will need a recommendation from a flight instructor to take a written test, so your preparation method and readiness for the test will be evaluated before you are allowed to take it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only exception to the above statement is knowledge tests for airline transport pilot certificates with airplane multi-engine class ratings taken after 31 July 2014.  These written tests do require specific groundschool training minimums, which are specified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1156&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.156&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you are instead training under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=51306a881979b899ed1c2b46a332516e&amp;amp;mc=true&amp;amp;node=pt14.3.141&amp;amp;rgn=div5&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 141&lt;/a&gt;, your school has a specific curriculum and examination authority approved by the FAA.  The specifics of your program will dictate what groundschool is required to take the relevant written exams.  The groundschool aeronautical knowledge baseline requirements are specified in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=51306a881979b899ed1c2b46a332516e&amp;amp;mc=true&amp;amp;node=sp14.3.141.f&amp;amp;rgn=div6&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 141 Subpart F&lt;/a&gt;.  For a private pilot certificate with an airplane category rating, these requirements are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;35 hours groundschool training in&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Applicable Federal Aviation Regulations for private pilot privileges, limitations, and flight operations;&lt;/li&gt;&#xA;  &lt;li&gt;Accident reporting requirements of the National Transportation Safety Board;&lt;/li&gt;&#xA;  &lt;li&gt;Applicable subjects of the “Aeronautical Information Manual” and the appropriate FAA advisory circulars;&lt;/li&gt;&#xA;  &lt;li&gt;Aeronautical charts for VFR navigation using pilotage, dead reckoning, and navigation systems;&lt;/li&gt;&#xA;  &lt;li&gt;Radio communication procedures;&lt;/li&gt;&#xA;  &lt;li&gt;Recognition of critical weather situations from the ground and in flight, windshear avoidance, and the procurement and use of aeronautical weather reports and forecasts;&lt;/li&gt;&#xA;  &lt;li&gt;Safe and efficient operation of aircraft, including collision avoidance, and recognition and avoidance of wake turbulence;&lt;/li&gt;&#xA;  &lt;li&gt;Effects of density altitude on takeoff and climb performance;&lt;/li&gt;&#xA;  &lt;li&gt;Weight and balance computations;&lt;/li&gt;&#xA;  &lt;li&gt;Principles of aerodynamics, powerplants, and aircraft systems;&lt;/li&gt;&#xA;  &lt;li&gt;If the course of training is for an airplane category or glider category rating, stall awareness, spin entry, spins, and spin recovery techniques;&lt;/li&gt;&#xA;  &lt;li&gt;Aeronautical decision making and judgment; and&lt;/li&gt;&#xA;  &lt;li&gt;Preflight action that includes—&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;How to obtain information on runway lengths at airports of intended use, data on takeoff and landing distances, weather reports and forecasts, and fuel requirements; and&lt;/li&gt;&#xA;  &lt;li&gt;How to plan for alternatives if the planned flight cannot be completed or delays are encountered.&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-08-27T15:04:40.487" LastActivityDate="2015-08-27T15:04:40.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19405" PostTypeId="1" CreationDate="2015-08-27T15:13:26.873" Score="5" ViewCount="2226" Body="&lt;p&gt;How many different versions of the P-51 Mustang DFF are there?&lt;/p&gt;&#xA;" OwnerUserId="9976" LastEditorUserId="14897" LastEditDate="2017-12-30T17:41:27.613" LastActivityDate="2017-12-31T00:12:29.740" Title="How many versions of the P-51 dorsal fin fillet are documented?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;p-51&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19406" PostTypeId="2" ParentId="19405" CreationDate="2015-08-27T16:03:13.597" Score="5" Body="&lt;p&gt;A quick search of Google Images seems to show only three major variations on the tail for production P-51 variants:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Razorback (all P-51A, B, and C variants; no dorsal strake and a higher rear fuselage line):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JnYuy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JnYuy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bubble canopy without the strake (seen on early D-variants)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0XFCo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0XFCo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the strake (seen on later production D variants, integrated fully into K and H models and retrofitted to earlier Ds, sometimes to the Razorback B/Cs):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jjUxn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jjUxn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XmJIg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XmJIg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N6rB5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N6rB5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is some difference in the prominence and exact shape of the fin fillet as the design continued to be developed; for all B/C/D variants it was a thin piece essentially bolted onto the strakeless frame. For the H variant in the bottom picture, it was integrated more fully into the fairing of the vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's one more I've seen and I'm not sure if there's just the one example, but there is a P-51 &quot;XR&quot; variant, &quot;Precious Metal&quot;, with dual counter-rotating props and further aerodynamic refinement, including a fairing behind the modified bubble canopy that narrows into a continuous strake along the aircraft's rear spine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WVIre.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WVIre.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other custom racing variants have existed over the years, all heavily modified from USAF production variants.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-27T16:03:13.597" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19407" PostTypeId="2" ParentId="19384" CreationDate="2015-08-27T16:18:39.393" Score="7" Body="&lt;h2&gt;Right Engine thrust&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The engine takes about 12 seconds to spool up from idle to full thrust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Auto-throttle had held both engines near idle during the approach to touchdown. The throttle levers should both be retarded from &quot;climb&quot; to &quot;idle&quot; position prior to touchdown. But only in the last two seconds before touchdown, after the aircraft emitted a warning, was the left throttle retarded - but the right throttle lever was not moved from the &quot;climb&quot; position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the left throttle lever was retarded, this disengaged auto-throttle, so  the right engine started to spool up to &quot;climb&quot; power setting as commanded on the right throttle lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So immediately after landing the right engine wasn't producing any thrust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust only developed gradually during the following 12 seconds as the aircraft traveled down the runway.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Rudder authority&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At landing the aircraft might be travelling at 140 knots. At this speed, deflection of the rudder by the pilot can still have significant effect and can counteract asymmetric engine thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft traveled down the runway, airspeed would have reduced and rudder authority gradually diminish at the same time as the right engine was spooling up to CL (climb) power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft ran off the runway at about 90 knots.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Nosewheel steering&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When using the rudder pedals for nose wheel steering, the steering angle starts to reduce at 40 knots and progressively reduces to zero degrees at 130 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the accident report,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the accident happened, the volume of precipitation was 0.6 mm. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So a combination of speed and a wet runway may have reduced the effectiveness of nosewheel steering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know, but I suspect that nosewheel steering may not be able to fully compensate for the yawing effect of left engine at idle and right engine at climb power.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Differential braking&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FDR also recorded the use of the rudder and the differential braking by the pedals as the aircraft veered to the left (probably in an attempt to maintain the plane on the runway and stop it). &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems that the crew &lt;em&gt;really&lt;/em&gt; needed to shutdown or idle the right engine to complete a landing within the boundary of the runway. &lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-10-31T16:22:58.933" LastActivityDate="2015-10-31T16:22:58.933" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19408" PostTypeId="2" ParentId="3853" CreationDate="2015-08-27T17:29:02.467" Score="1" Body="&lt;p&gt;The purpose of the cross feed valve or cross feed circuit in the airplanes is to separate the fuels in different tanks, especially in the wings (both left and right wings and fuselage) so that one tank will not affect another in terms of leakage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other purpose is for the emergency use. If left fuel pump encounters a problem, the right fuel pump will pump fuel from right tank and supply fuel to both engine one and two, through the crossfeed that is automatically opened. Vice versa to right fuel pump.&lt;/p&gt;&#xA;" OwnerUserId="9992" LastEditorUserId="1696" LastEditDate="2015-08-27T17:58:54.307" LastActivityDate="2015-08-27T17:58:54.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19409" PostTypeId="2" ParentId="19368" CreationDate="2015-08-27T17:56:40.607" Score="7" Body="&lt;p&gt;Short answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Vertical tails create more yawing moment per unit of drag.&lt;/li&gt;&#xA;&lt;li&gt;Vertical tails create less adverse rolling moment for a given yawing moment.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The rudder works by creating a side force, just like a wing creates lift. This incurs a small amount of drag (about a tenth of the side force).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even on a swept wing their lever arm in lengthwise direction is small compared to the wingspan. If the winglets would be used as rudders, they would be most efficient as drag devices, because then their force will act on a longer lever. This has been done on flying wings (note that the SB-13 tailless glider has a maximum rudder deflection of 70° in order to create drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cs5Gk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cs5Gk.jpg&quot; alt=&quot;SB-13 in flight with Hans-Jürgen Berns at the controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SB-13 in flight (picture &lt;a href=&quot;http://www.akaflieg-braunschweig.de/prototypen/sb13/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This makes the use of a rudder vastly more efficient for creating a yawing moment than using winglets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deflection of winglet rudders will also change the lift distribution on the wing, so they do not only create a yawing moment, but also a rolling moment. Vertical tails wich are high above the roll axis also add a rolling moment, but this is comparatively small to the rolling moment of a winglet with rudder on a high aspect ratio wing. In both cases, the rolling moment acts against the desired roll direction, so it is preferable again to create the yawing moment with the vertical tail.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-08-27T17:56:40.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19410" PostTypeId="1" CreationDate="2015-08-27T18:17:16.593" Score="11" ViewCount="2661" Body="&lt;p&gt;When holding at or below 14,000 feet, the time for each leg is 1 minute. However, above that altitude, the legs are flown for 2 minutes, and the turns for 1 minute and half.&#xA;Are these differences due to airspeed, or any other recommendation? &lt;/p&gt;&#xA;" OwnerUserId="9458" LastEditorUserId="1696" LastEditDate="2015-09-01T15:03:49.613" LastActivityDate="2017-03-13T02:46:39.153" Title="Why do holds at or below 14,000 feet have different procedures?" Tags="&lt;holding&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19411" PostTypeId="1" AcceptedAnswerId="19413" CreationDate="2015-08-27T18:18:41.783" Score="22" ViewCount="9330" Body="&lt;p&gt;I've been reading a lot about the Soviet and Russian military aircraft, and it seems a lot of them are built to work on dirt runways, or modified to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this accomplished? Is it a simple thing to modify aircraft in this way? Is it just a matter of strengthening the undercarriage and upgrading the tires for more stress? Or is something harder involved, like maybe strengthening the fuselage frame?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTE: let's exclude worries about foreign objects going into the engines. Right now I'm only interested in the difference between paved and dirt runways as far as landing gear and strength are concerned.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2019-04-08T17:03:09.800" Title="How are modern jets modified to takeoff/land on a dirt runway?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;landing-gear&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19413" PostTypeId="2" ParentId="19411" CreationDate="2015-08-27T20:36:11.570" Score="43" Body="&lt;p&gt;Just to roll around on &quot;unimproved&quot; airfields (grass/dirt/gravel strips), the biggest thing planes need is simply a decent set of tires:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/4/4f/Mig-29_on_landing.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/4/4f/Mig-29_on_landing.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This MiG-29UN trainer shows off the fairly beefy main tires put on these planes specifically to allow them to more easily roll over minor imperfections in the runway/taxiway surface, including dirt/gravel/grass strips (though here it's landing on a traditional asphalt/concrete surface). Compare these to the relatively small gear wheels and low-aspect rubber on the similarly-sized F-16:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rlLvO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rlLvO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.f-16.net/g3/var/resizes/f-16-photos/album39/album32/6676.jpg?m=1371907365&quot; rel=&quot;noreferrer&quot;&gt;f-16.net&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, your question oversimplifies things, because &quot;foreign object debris&quot; or FOD is in fact a primary danger of unpaved airstrips for jets, and this danger has to be accounted for in the design. Here's the main reason the MiG-29 can take off from dirt:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c73AL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c73AL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FAls1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FAls1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MiG-29s and similarly-minded Su-27s, and their variants, have special doors to close off the lower intakes normally used in flight, instead drawing in air through the gill-like ports over the top of the wing strakes. This prevents the engine from ingesting dust, rocks, birds, rodents, etc on takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This engine protection system, while effective, adds mechanical complexity and weight which U.S. designers and military brass have generally thought unnecessary given that requirements rarely include the ability to operate from unimproved strips. Most U.S. fighters in the jet age, therefore, have had to operate from airbases with some form of paved runway surface (and the U.S. military actually has higher standards for runway surface quality than most international airports). The U.S. arsenal does, however, have several aircraft that are specifically designed to operate from rudimentary airstrips at forward bases. These designs avoid FOD damage primarily by keeping the engines up as high as the design will allow. For instance, the A-10's two engines are on pods angled up on the fuselage between the wings and tail for a variety of reasons including FOD avoidance: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VP6no.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VP6no.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the other designs in the Western arsenal that can do this are high-wing designs with wing-mounted engines, which keep them out of the dust produced by takeoff and landing in a similar fashion. Here are a C-130 and C-17 landing at an Afghanistan forward base:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9uN92.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9uN92.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VvJVG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VvJVG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Harrier is a notable exception to this general strategy by Western designers of just keeping the engines out of any debris cloud. While it's probably not done routinely, a Harrier can set down just about anywhere, and as this picture shows, it ingests no small amount of dust in the process:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lP3qp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vuxCC.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-04-08T16:27:54.177" LastActivityDate="2019-04-08T16:27:54.177" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="19414" PostTypeId="1" CreationDate="2015-08-27T21:28:08.607" Score="6" ViewCount="1374" Body="&lt;p&gt;The 787 active gust alleviation system, similar to the system used on the B-2 bomber, improves ride quality during turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ride quality in a B2 bomber means a more stable weapons platform.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ride quality in a 787 means passenger comfort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I must add that I have never flown in a 787.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the 787 more comfortable than a normal plane of similar size?&lt;/p&gt;&#xA;" OwnerUserId="9993" LastEditorUserId="22726" LastEditDate="2019-02-16T22:31:24.017" LastActivityDate="2019-02-16T22:31:24.017" Title="Does the 787 gust alleviation system make a more comfortable ride or for a more stable aircraft?" Tags="&lt;boeing-787&gt;&lt;fly-by-wire&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="19415" PostTypeId="1" AcceptedAnswerId="19421" CreationDate="2015-08-27T21:59:10.570" Score="5" ViewCount="11197" Body="&lt;p&gt;I know that helicopters blades are like rotating wings that generate lift in the same way, but how does this make a helicopter hover?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other question; how does the tail rotor help with the balance of the helicopter and why does it have to be on the left side of the vertical stabilizer instead of in the center?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-08-27T22:18:16.137" LastActivityDate="2015-08-28T16:42:59.713" Title="How do helicopters hover?" Tags="&lt;helicopter&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19416" PostTypeId="2" ParentId="19414" CreationDate="2015-08-27T22:10:09.007" Score="7" Body="&lt;p&gt;Both, but the improved comfort and stability are only side effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/11336/what-is-a-gust-alleviation-system/11337?s=3%7C0.0676#11337&quot;&gt;gust alleviation system&lt;/a&gt; uses trailing edge flaps (ailerons, elevators and sometimes spoilers) to counteract local lift changes caused by flying through up- or downdrafts. The flap is deflected to change the local incidence and camber of the wing in order to reduce the change in lift due to gusts. This helps to lower the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9409/how-strong-is-the-a380-fuselage-wing-joint/9418?s=1%7C0.1116#9418&quot;&gt;collective cyclic loads the structure has to endure over time&lt;/a&gt; and allows to use a lighter, less strong structure, or it allows to stretch out the inspection intervals for the same structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the structure will experience smaller deviations from the average load factor, you, the passenger, will experience a smoother ride in gusty air. In calm air the system will not make any difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also pitch changes are smaller since the flight will be less bouncy and the tail surface lift can be smoothed out over time in the same way. Therefore, a gust alleviation system works similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on/8061?s=4%7C0.0525#8061&quot;&gt;artificially enhanced stability&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A major problem is the unavoidable lag in reaction. If the bending moment in the wing spar is measured, a computer has to calculate the appropriate response, has to command changes in hydraulic pressure and flight control surfaces need be moved. By the time the flow around the wing is affected by the flaps, the gust has long passed. Therefore, it needs instruments like &lt;a href=&quot;https://en.wikipedia.org/wiki/Laser_Doppler_velocimetry&quot; rel=&quot;nofollow noreferrer&quot;&gt;laser anemometers&lt;/a&gt; to measure the wind ahead of the airplane so the reaction can be timed correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to your last question would primarily be based on opinion, so I leave answering it to you.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-27T22:10:09.007" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19418" PostTypeId="2" ParentId="19333" CreationDate="2015-08-27T22:19:43.210" Score="15" Body="&lt;p&gt;It's not just the big bombers flying long missions; you'd be surprised how many of the sorties flying over Afghanistan, Iraq, Syria, Libya etc originate from airbases in Northern Europe with refueling stops over the Mediterranean (because closer airbases aren't available or are congested with aircraft from other forces or that have shorter ranges).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short and simple answer is, aircraft crews eat whatever they can bring with them, that won't make a huge mess in the process. A bigger plane like a B-52 has some room to get up and move, so the pilot may take 15 minutes during ingress or egress, duck out to the entryway and eat a box lunch, then come back and relieve the co-pilot so he can do the same thing. Radar, nav and weapons systems officers typically have a little room behind or between seats to step away and eat, or they'll duck into the entryway as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In smaller aircraft, space is more limited, but the pilot's flight suit will still have plenty of pockets to carry food and drink pouches. There are some considerations as to the exact type of food, especially in one- and two-seat jets. A crewman has to prevent &quot;foreign object damage&quot; to the switches and displays in his cockpit, or else his crew chief (and his CO) will be all over him about it. Good choices include pre-wrapped bar-type snacks; granola, protein, energy, some types of candy bars, whatever. Depending on what's available in the mess hall, pilots may be able to assemble simple tortilla wraps with lunch meats and cheese, which are edible with one hand and fewer crumbs than a bread sandwich. Anything that can be put in a drink pouch, like broth or tomato soup, is also a possibility. Bad choices include things like trail mix, peanuts, M&amp;amp;Ms etc, as well as anything too loose to reliably keep together with one hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bigger concern is, what to do when it comes back out? The B-52 has a rudimentary &quot;head&quot;, with what amounts to a camping toilet (a bucket with a plastic bag liner and a toilet seat over the top) called the &quot;honeypot&quot;. However, if it's used, the crewman who used it is often tasked by the crew chief with cleaning it, so it's considered a last resort. Crew of smaller aircraft have no such luxury, and unlike NASA astronauts, they wouldn't be caught dead wearing a diaper. Most fighter pilots eat a &quot;low-residue&quot; meal for the two or three meals before a very long mission or ferry flight, to reduce the chance they'll have to BM during the flight (some take an anti-diarrheal like Immodium as a preventive measure). Urination is a little easier to deal with, for men at least; pilots carry packets with an absorbent powder (not unlike what's in diapers) called &quot;piddle packets&quot;. The difficulty is typically in... &quot;maneuvering&quot;. You have to get the equipment out of your flight suit, when you're strapped down to the point of suffocation in a 6-point harness, then be able to aim into the piddle pack. Finally, you have to store this bag of piss somewhere until you get back to base, and as Rhino Driver is fond of explaining, if that base is a carrier, you have to make sure it's extra-secure, or on capture it'll go zooming forward toward the firewall and explode in a shower of damp absorbent crystals. Even if your squadron-mates don't see you getting out of the plane covered in this stuff, your crew chief will be sure to tell them all about it.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-08-27T22:19:43.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19420" PostTypeId="1" AcceptedAnswerId="19423" CreationDate="2015-08-27T23:17:26.067" Score="4" ViewCount="2134" Body="&lt;p&gt;I know there are ways turbulence can be reduced, but what are these ways that keep the ride comforting and also with better stability.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="62" LastEditDate="2015-08-28T01:38:08.030" LastActivityDate="2020-11-12T08:46:31.470" Title="What are some ways to decrease turbulence?" Tags="&lt;airliner&gt;&lt;turbulence&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19421" PostTypeId="2" ParentId="19415" CreationDate="2015-08-27T23:18:26.810" Score="12" Body="&lt;p&gt;To understand how a helicopter works (and in fact the mechanics of other aircraft too), it's helpful for you to be familiar with a key concept in physics, called Newton's Third Law of Motion. It says, in general terms, &quot;for every action, there is an equal and opposite reaction&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a simple thought experiment. Picture yourself wearing a pair of rollerskates, standing up, holding a basketball. Now, throw the basketball out in front of you using a two-hand pass (bring it to your chest and push it out in front of you). You'll find yourself moving backwards on the skates. You won't be moving as fast backwards as the ball will be moving forwards, because you have more mass than the ball, but you'll move, because the force of you pushing the ball out forward created an equal force moving you in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A helicopter, and in fact most powered aircraft, work the same way. when a helicopter's rotor moves through the air, it pushes air downwards through a combination of its airfoil design, which moves air downwards as it passes over the top of the rotor, and an upward angle to the blade relative to the oncoming air that pushes the air with the underside of the rotor. By Newton's Third Law, the force pushing the air downward creates an equal and opposing force pulling the rotor, and the helicopter attached to it, up into the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vckn0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vckn0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To hover, all that's required is for this force pulling the helicopter up (you can consider it as either &quot;lift&quot; or &quot;thrust&quot;) to equal the force of gravity on the helicopter, which is its weight. If these forces balance, the helicopter will remain the same distance off the ground. If lift is greater then weight, it will rise into the air, while if weight it greater, it will sink or fall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, normal aircraft have to move forward through the air in order for their wing to get the airflow needed to generate lift. A helicopter, by rotating its wing, can produce the airflow over the lift surface without the entire helicopter having to move forward (or backward or sideways for that matter). So, it can rise straight up into the air and truly hover over a single spot on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vhbor.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vhbor.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail rotor of a helicopter is necessary to counter another force produced by the helicopter; torque. Torque is similar to force - really it is a force - but it's being produced in a circular direction instead of a straight line. The helicopter's engine uses torque to spin its rotor. Again, by Newton's Third Law, if the rotor of the helicopter is being spun clockwise by the engine, the helicopter itself will begin to spin counter-clockwise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To counteract this torque, most helicopters have a second, smaller rotor which works the same way as the big one, but directs the force of its thrust sideways in the opposite direction to the way the helicopter's body wants to spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8zHWT.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8zHWT.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sideways rotor doesn't necessarily have to be on the tail, but it works best if it's on the end of a long lever arm, such as the tail boom of the helicopter. The closer it is to the main rotor's shaft, the more thrust it has to produce in order to counteract the torque of the main rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't have to be on the side of the tail either; many modern helicopter designs have the tail rotor spinning inside an aerodynamic duct in the middle of the tail:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GBCwf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GBCwf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters also don't necessarily have to have a tail rotor at all; all that's required is equal, opposing torque to that of the main rotor. A common substitute for a tail rotor is a second, counter-rotating main rotor:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Russian_Air_Force_Kamov_Ka-50.jpg/1280px-Russian_Air_Force_Kamov_Ka-50.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/0c/Russian_Air_Force_Kamov_Ka-50.jpg/1280px-Russian_Air_Force_Kamov_Ka-50.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Inbound_Choppers_in_Afghanistan_2008.jpg/1280px-Inbound_Choppers_in_Afghanistan_2008.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Inbound_Choppers_in_Afghanistan_2008.jpg/1280px-Inbound_Choppers_in_Afghanistan_2008.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-08-28T16:42:59.713" LastActivityDate="2015-08-28T16:42:59.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19422" PostTypeId="2" ParentId="19415" CreationDate="2015-08-27T23:26:42.767" Score="7" Body="&lt;p&gt;The major forces acting on the helicopter are the same as that of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The helicopter wings generate lift which is perpendicular to the rotor plane (the planes in which the rotor rotates).&lt;/li&gt;&#xA;&lt;li&gt;This lift vector is rotated to the forward to get the thrust.&lt;/li&gt;&#xA;&lt;li&gt;The weight of the helicopter acts vertically downwards.&lt;/li&gt;&#xA;&lt;li&gt;The drag is opposite to the direction of movement of the helicopter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xKySm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xKySm.jpg&quot; alt=&quot;Forces on Helicopter&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:www.danubewings.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At hover, this lift is simply equal to the weight of the helicopter. There is no forward movement and thrust is equal to zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft, the forward motion of the aircraft creates airflow over the wings, which in turn generate lift. In helicopters, the blades are rotated to generate airflow over the blades. However, the rotation of the blades causes a torque to act on the helicopter, which has to be balanced to prevent the rotation of the helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various ways to counteract this torque. In one of the most widely used methods, introduced successfully by Igor Sikorsky in VS-300, this balancing moment is provided by the tail rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YRGTc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YRGTc.png&quot; alt=&quot;Helicopter anti-torque&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Heli_tail_rotor_dia.png#/media/File:Heli_tail_rotor_dia.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heli tail rotor dia&lt;/a&gt;&quot; by FAA - FAA - H808321 Rotorcraft Flying Handbook. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no need for the tail rotor to be in any particular side of the vertical fin. For example, the Mi-8 had it on the starboard (right) side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ru2fn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ru2fn.jpg&quot; alt=&quot;Mi-8&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.military-today.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mi-17, which was developed from Mi-8, had the tail rotor shifted to the port side of the vertical fin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0xxzZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0xxzZ.jpg&quot; alt=&quot;Mi-17 V5&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:www.forceindia.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helicopters like the EC-145 has the tail rotor in the middle of the vertical fin, an arrangement called the fenestron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BO0Di.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BO0Di.jpg&quot; alt=&quot;EC- 145&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: blogs.star-telegram.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the helicopters need not even have a tail rotor for hover, The necessary anti torque can be generated by multiple ways, like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tandem rotors in case of CH 47&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qz1aX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qz1aX.jpg&quot; alt=&quot;CH 47&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.helis.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coaxial rotors in case of Ka 50&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O2koZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O2koZ.jpg&quot; alt=&quot;Ka 50&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Russian_Air_Force_Kamov_Ka-50.jpg#/media/File:Russian_Air_Force_Kamov_Ka-50.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Russian Air Force Kamov Ka-50&lt;/a&gt;&quot; by Dmitriy Pichugin - &lt;a href=&quot;http://www.airliners.net/photo/Russia---Air/Kamov-Ka-50/0920728/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airliners.net/photo/Russia---Air/Kamov-Ka-50/0920728/L/&lt;/a&gt;. Licensed under GFDL 1.2 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intermeshing rotors like K-Max&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iLC85.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iLC85.jpg&quot; alt=&quot;K- MAX&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.ainonline.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NOTAR system like MD 520N&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4vylp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4vylp.jpg&quot; alt=&quot;MD 520N&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Md500n.g-smac.arp.jpg#/media/File:Md500n.g-smac.arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Md500n.g-smac.arp&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Arpingstone&quot;&gt;Adrian Pingstone&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hiller HOE-1 used a tipjet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UCEzx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UCEzx.jpg&quot; alt=&quot;Hiller HOE-1&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.aerospaceweb.org&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-28T12:37:54.310" LastActivityDate="2015-08-28T12:37:54.310" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19423" PostTypeId="2" ParentId="19420" CreationDate="2015-08-28T00:08:22.873" Score="4" Body="&lt;p&gt;There is no way to really decrease turbulence per-se since its a factor of the air around you. There are ways to mitigate its effects and some are. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Climb:&lt;/strong&gt; In some cases the air higher up is less turbulent or you can climb over the weather system causing the turbulent air. In this case climbing to a higher altitude may help &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Divert:&lt;/strong&gt; Similar to the climb situation you can divert around the turbulent air if you know where its occurring.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Timing:&lt;/strong&gt; This is the one you may have the least control over if you are talking about commercial flying and its not always true but generally speaking the winds and thermal activity tend to be calmer in the early morning and evening. Flying around these times may allow you to find smoother air. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Size:&lt;/strong&gt; Again this one is hard to control but there is some truth to the fact that big planes will be less effected by turbulent air than small planes. By this I mean that a 777 is going to bump around less than a Piper Cherokee. But it holds more or less true across the board. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="595" LastEditDate="2015-08-28T05:44:58.290" LastActivityDate="2015-08-28T05:44:58.290" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19424" PostTypeId="1" AcceptedAnswerId="19426" CreationDate="2015-08-28T00:29:26.437" Score="34" ViewCount="5937" Body="&lt;p&gt;In looking at European-designed fighters of the 4th and 4.5th generation, I keep seeing a common design feature; a box-like structure built into the tail, often in the top half or third. Some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Saab Gripen&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/foBMA.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/foBMA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mirage 2000&lt;/strong&gt; (this one's more complex and less box-like but the arrangement is very similar)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QbJXX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QbJXX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Rafale&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MgVG6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MgVG6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Eurofighter Typhoon&lt;/strong&gt; (this one looks markedly different, much lower and more like an intake)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kXII1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kXII1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Panavia Tornado&lt;/strong&gt; (this one has two main protrusions from the tail, one much like the Typhoon's, the other more like the Gripens or Rafales)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sqMHl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sqMHl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SEPECAT Jaguar&lt;/strong&gt; (you know what you're looking at by now)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Gtjie.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gtjie.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What is this box? My best guess is some sort of avionics/sensor package, maybe RWR/missile warning. What's odd to me is that this box-in-tail arrangement is not seen on any relatively late-model U.S. or Soviet fighter; you'd think if the Europeans were onto something with this placement, the U.S. or Soviets would have tried it out at least once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15 has what I think is an RWR probe on top of the left tail, but the tail itself is pretty clean:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0JJbU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0JJbU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16 does have a boxy construction flaring out at the top of the tail, but the front is clean:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2Nvo1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Nvo1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F/A-18 has some trailing-edge bulges but again very clean:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/isiUa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/isiUa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Su-27, ditto to the F-18 (it does have that big probe between the engines though):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sxY1s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sxY1s.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MiG-29, same thing:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/X4iJ8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X4iJ8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could go on but you get the point, Soviet and U.S fighters seem to have passed on whatever this package is in the tail. So, what is it, why is the arrangement limited to European fighters (for the most part) and how do other regional designers accomplish whatever these do?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="15311" LastEditDate="2018-06-10T13:01:49.690" LastActivityDate="2018-06-10T13:01:49.690" Title="What are these boxes built into the tails of some fighters?" Tags="&lt;military&gt;&lt;avionics&gt;&lt;fighter&gt;&lt;feature-identification&gt;&lt;sensors&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="19425" PostTypeId="2" ParentId="19411" CreationDate="2015-08-28T00:30:07.070" Score="22" Body="&lt;p&gt;The two main issues faced by aircraft landing on rough runways are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Ingestion of &lt;a href=&quot;https://en.wikipedia.org/wiki/Foreign_object_damage&quot; rel=&quot;noreferrer&quot;&gt;FOD&lt;/a&gt; in the engines, and&lt;/li&gt;&#xA;&lt;li&gt;Damage to the landing gear.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In case of the rough landing, one of the best ways is to distribute weight using larger and higher number of tyres. For example, compare the landing gear of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_C-17_Globemaster_III&quot; rel=&quot;noreferrer&quot;&gt;C-17&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EBTj6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EBTj6.jpg&quot; alt=&quot;C 17 landing gear&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A_U.S._Air_Force_Airman_inspects_the_landing_gear_of_a_C-17_Globemaster_III_aircraft,_July_1,_2014,_on_the_flight_line_at_Joint_Base_Charleston,_S.C._The_maintainers_performed_checks_and_maintenance_around_140701-F-EV310-009.jpg#/media/File:A_U.S._Air_Force_Airman_inspects_the_landing_gear_of_a_C-17_Globemaster_III_aircraft,_July_1,_2014,_on_the_flight_line_at_Joint_Base_Charleston,_S.C._The_maintainers_performed_checks_and_maintenance_around_140701-F-EV310-009.jpg&quot; rel=&quot;noreferrer&quot;&gt;A U.S. Air Force Airman inspects the landing gear of a C-17 Globemaster III aircraft, July 1, 2014, on the flight line at Joint Base Charleston, S.C. The maintainers performed checks and maintenance around 140701-F-EV310-009&lt;/a&gt;&quot; by A1C Clayton Cupit - &lt;a href=&quot;http://www.defenseimagery.mil/imageRetrieve.action?guid=18df79c5d609dbaa0679ab32d9e6aea6e76200c6&amp;amp;t=2&quot; rel=&quot;noreferrer&quot;&gt;http://www.defenseimagery.mil/imageRetrieve.action?guid=18df79c5d609dbaa0679ab32d9e6aea6e76200c6&amp;amp;t=2&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with that of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;Boeing 777&lt;/a&gt;, which has about the same &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_gross_weight#Maximum_takeoff_weight_.28MTOW.29&quot; rel=&quot;noreferrer&quot;&gt;maximum takeoff weight&lt;/a&gt; (MTOW).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LeO0E.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LeO0E.jpg&quot; alt=&quot;777 Landing gear&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft like &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-27&quot; rel=&quot;noreferrer&quot;&gt;Su-27&lt;/a&gt; use a FOD deflector in their wheels to reduce the damage due to FOD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X9aXH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X9aXH.jpg&quot; alt=&quot;Su 27&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: maybach300c.blogspot.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to keep the engines clear of FOD is to have them mounted high on the wing, where the FOD ingestion is reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DcTi4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DcTi4.jpg&quot; alt=&quot;C 17&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.defense.gov&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, the engines can be mounted high on the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2LblO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2LblO.jpg&quot; alt=&quot;A 10&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: theaviationist.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case this is not possible in the case of a high-performance combat aircraft, the inlet design has to be modified. The Russians used this extensively as their operational doctrine demanded it. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot; rel=&quot;noreferrer&quot;&gt;MiG-29&lt;/a&gt; main engine inlets could be closed for operation from rough runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7rInv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7rInv.jpg&quot; alt=&quot;Mig 29 inlets&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.reddit.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the main inlets are closed, the air for engine is obtained through inlets on the top of the wings, which are shielded from the debris below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/q7vG5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/q7vG5.jpg&quot; alt=&quot;Mig 29&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-31T12:39:40.793" LastActivityDate="2015-08-31T12:39:40.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19426" PostTypeId="2" ParentId="19424" CreationDate="2015-08-28T00:57:10.617" Score="30" Body="&lt;p&gt;You're right. It's the ECM/EW antenna/equipment (fairing) in all the aircrafts except Typhoon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This photo shows the details of EW/ECM suite in Gripen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lQvy5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lQvy5.jpg&quot; alt=&quot;Gripen&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.w54.biz&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Typhoon, it is the engine bleed air heat exchanger. The part is in detail here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YYkFJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YYkFJ.jpg&quot; alt=&quot;Typhoon Heat exchanger&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: b-domke.de&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-28T00:57:10.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19427" PostTypeId="1" AcceptedAnswerId="19428" CreationDate="2015-08-28T01:39:51.377" Score="6" ViewCount="2696" Body="&lt;p&gt;&lt;a href=&quot;https://www.google.co.uk/search?es_sm=93&amp;amp;biw=1366&amp;amp;bih=599&amp;amp;tbm=isch&amp;amp;sa=1&amp;amp;q=%E7%AB%B9%E3%81%A8%E3%82%93%E3%81%BC&amp;amp;oq=%E7%AB%B9%E3%81%A8%E3%82%93%E3%81%BC&amp;amp;gs_l=img.3..0l9j0i4i37.212324.212324.0.212643.1.1.0.0.0.0.175.175.0j1.1.0....0...1c.1.64.img..0.1.174.75kOga4_3xM#tbm=isch&amp;amp;q=%E3%82%BF%E3%82%B1%E3%82%B3%E3%83%97%E3%82%BF%E3%83%BC&quot; rel=&quot;nofollow noreferrer&quot;&gt;Takekoputa(タケコプター)&lt;/a&gt; is one of the most famous and common gadget in the Japanese manga series &lt;strong&gt;Doraemon&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless the power issue, Can it be used to fly in real world, as like as in the animation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4mWwY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4mWwY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-08-28T17:35:54.300" LastActivityDate="2015-08-28T17:35:54.300" Title="Can Somebody use Takekoputa to fly?" Tags="&lt;helicopter&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ClosedDate="2015-08-29T15:53:39.917" ContentLicense="CC BY-SA 3.0" />
  <row Id="19428" PostTypeId="2" ParentId="19427" CreationDate="2015-08-28T01:58:36.980" Score="12" Body="&lt;p&gt;In a manner of speaking yes (although its highly unlikely). If the propellor on his head can generate enough lift to get his mass off the ground there is nothing to say he cant fly. That does not mean that the flight will be very stable or controllable but it may lift off. Since the animal does not have the equivalent of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tail_rotor&quot; rel=&quot;noreferrer&quot;&gt;tail rotor&lt;/a&gt; the torque effect generated from the propellor may spin him around. It does appear there may be flyable toy versions &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FWyCI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FWyCI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although for what its worth there is no identifiable power plant that is spinning this head propellor...  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-08-28T13:11:54.577" LastActivityDate="2015-08-28T13:11:54.577" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19429" PostTypeId="2" ParentId="19427" CreationDate="2015-08-28T01:58:54.260" Score="6" Body="&lt;p&gt;I assume that the thing on his head is a propellor&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, then in theory yes, it could fly. If the propellor rotates fast enough, and the rest of him is light enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that his body, however, would rotate in the opposite direction to the propellor, likely making him uncontrollable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory he could lift off the ground, in practice he would almost certainly be uncontrollable&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-08-28T01:58:54.260" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19430" PostTypeId="2" ParentId="19420" CreationDate="2015-08-28T02:20:09.250" Score="1" Body="&lt;p&gt;You're not going to reduce the actual turbulence, but you can smooth out the ride a little bit.  Slowing down certainly helps.  If you are doing 230KIAS and you hit some bumps it is going to hurt more than at 180KIAS.  The PC12 is notorious for this in my experience.  I found in the Navajo that dropping the gear made the airplane a little more stable in rough weather in the mountains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I heard an old-timer tell me that pushing the props forward helped because the props work like a gyroscope and remain &quot;rigid in space.&quot;  I tried it on a particularly rough day where I was making a round trip in SE Alaska in a PA32 and noticed no difference, maybe someone with a physics background could chime in and explain how the guy is right, but in practice, it was just as rough on the way over as on the way back.&lt;/p&gt;&#xA;" OwnerUserId="9822" LastActivityDate="2015-08-28T02:20:09.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19431" PostTypeId="1" AcceptedAnswerId="19435" CreationDate="2015-08-28T03:47:08.977" Score="3" ViewCount="318" Body="&lt;p&gt;Could this be used in place of or in addition to a pitot-static system?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-28T08:46:37.010" Title="Can a laser Doppler anemometer be used to measure airspeed?" Tags="&lt;sensors&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19432" PostTypeId="2" ParentId="19391" CreationDate="2015-08-28T04:00:24.580" Score="21" Body="&lt;p&gt;24 December 1982; CAAC Ilyushin 18B; Canton (Guangzhou), China: The aircraft was on a scheduled domestic flight when an onboard fire broke out as a result of a carelessly discarded cigarette. The aircraft landed and the passengers and crew evacuated, but 25 of the 50 passengers were killed. All 11 crew members survived. &lt;a href=&quot;http://www.airsafe.com/events/airlines/prc.htm&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-28T04:00:24.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19434" PostTypeId="1" AcceptedAnswerId="19438" CreationDate="2015-08-28T05:11:45.340" Score="4" ViewCount="2107" Body="&lt;p&gt;I'm curious about the aircraft manufacturer names who still interested in including the VSD on lower part of Nav Display (I read about Boeing 737 only). Are there any other guys on this filed still? I know this would be useful during the landing and takeoff.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="14897" LastEditDate="2019-04-11T16:48:48.670" LastActivityDate="2019-04-11T19:32:38.750" Title="Which aircraft manufacturers still include Vertical Situation Displays (VSD) feature in their cockpits?" Tags="&lt;navigation&gt;&lt;avionics&gt;&lt;display&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19435" PostTypeId="2" ParentId="19431" CreationDate="2015-08-28T05:19:19.193" Score="7" Body="&lt;h1&gt;In place of pitot-static system&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;No, because it measures different physical quantity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Laser Doppler anemometer measures velocity of the stream¹. But pitot-static system does &lt;em&gt;not&lt;/em&gt;. Pitot-static system measures &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamic_pressure&quot;&gt;&lt;em&gt;dynamic pressure&lt;/em&gt;&lt;/a&gt; and expresses it as airspeed at which that dynamic pressure would occur at sea level on an &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Standard_Atmosphere&quot;&gt;ISO standard day&lt;/a&gt;².&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since lift and control effectiveness depend on dynamic pressure, that is exactly the quantity the pilot needs to see. Laser Doppler anemometer does not provide it, therefore it cannot replace pitot-static system.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;In addition to pitot-static system&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Anything can be used in addition to what we have. But the question is whether there is a reason to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For flying the aircraft, true airspeed is not needed and for determining the wind speed by comparing true airspeed and ground speed the airspeed can be estimated well enough from indicated airspeed, pressure and temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However a laser anemometer has the advantage of being able to measure the wind speed &lt;em&gt;ahead&lt;/em&gt; of the aircraft. This could be used for load alleviation (the system needs to know about the gusts a bit in advance so it can move the control surfaces in advance) and it could perhaps be used for detecting wind shear, though I am not sure how feasible such anemometer measuring wind speed hundreds of metres ahead is.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ A.k.a. true airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² That quantity is called &lt;a href=&quot;https://en.wikipedia.org/wiki/Equivalent_airspeed&quot;&gt;equivalent airspeed&lt;/a&gt;. That is intended quantity, but the measurement is subject to various errors. The raw output of the pitot tube is called &lt;a href=&quot;https://en.wikipedia.org/wiki/Indicated_airspeed&quot;&gt;indicated airspeed&lt;/a&gt; and the value corrected for positional errors (due to the air-stream impacting the pitot tube at an angle) is called &lt;a href=&quot;https://en.wikipedia.org/wiki/Calibrated_airspeed&quot;&gt;calibrated airspeed&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-08-28T08:46:37.010" LastActivityDate="2015-08-28T08:46:37.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19436" PostTypeId="1" CreationDate="2015-08-28T07:56:24.897" Score="5" ViewCount="224" Body="&lt;p&gt;I know that the two large aviation regulatory authorities are the FAA and EASA, but every country also has its own civil aviation authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Focusing on airliners that need to operate all over the world, are they designed to meet FAA and EASA requirements only or are they subject to the regulations of every country in which they operate's regulatory authority?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, where does ICAO come into the picture?&lt;/p&gt;&#xA;" OwnerUserId="2355" LastActivityDate="2015-08-28T10:26:35.643" Title="How are aviation regulations treated on a global stage?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19438" PostTypeId="2" ParentId="19434" CreationDate="2015-08-28T10:04:53.340" Score="6" Body="&lt;h1&gt;VSD&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Boeing have a &lt;a href=&quot;http://www.google.com/patents/US7783393&quot; rel=&quot;noreferrer&quot;&gt;patent&lt;/a&gt; on a VSD (Vertical Situation Display), which is part of the &lt;a href=&quot;https://aerospace.honeywell.com/news/vertical-situation-display-capable-egpws-available-for-737ng-retrofit&quot; rel=&quot;noreferrer&quot;&gt;Honeywell EGPWS&lt;/a&gt; (Enhanced Ground Proximity Warning System) which first appeared as an option on 737s about twelve years ago I think.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The system will be offered by early &lt;strong&gt;2003&lt;/strong&gt; as a customer option on in-production 737s and by retrofit on 737-600/-700/-800/-900 airplanes already in service. Implementation of the system on other Boeing models is under consideration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;- Boeing &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_20/vsd_story.html&quot; rel=&quot;noreferrer&quot;&gt;&quot;Aero&quot; magazine&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a6Zhz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a6Zhz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if Boeing offer licences at acceptable terms to their competitors, or if Honeywell make available, to other aircraft makers, products that incorporate features licensed from those patents.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;CFIT&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It is possible that other manufacturers have equivalent options for alerting pilots of potential CFIT (Controlled Flight Into Terrain).&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;TAWS &amp;amp; EGPWS&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The FAA, for example, requires aircraft be fitted with systems that comply with &lt;a href=&quot;https://en.wikipedia.org/wiki/Terrain_awareness_and_warning_system&quot; rel=&quot;noreferrer&quot;&gt;TAWS (Terrain Awareness Warning Systems)&lt;/a&gt; requirements. EGPWS systems satisfy that requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TAWS requires a terrain awareness display but I dont think it requires something specifically like Boeing's VSD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus for example, on at least their A350 and A380 models, have a navigation display that incorporates &quot;vertical flightpath data&quot;. I guess they don't call it a VSD. They also have what I think is a fairly common type of terrain display showing &quot;peaks&quot; ahead of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f2Es5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f2Es5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;&lt;a href=&quot;https://i.stack.imgur.com/zYLTx.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zYLTx.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;- Sources: &lt;a href=&quot;http://www.flightglobal.com/news/articles/airbus-hopes-a350-flightdeck-offers-best-of-both-worlds-with-a380-technology-and-high-205721/&quot; rel=&quot;noreferrer&quot;&gt;FlightGlobal&lt;/a&gt; and Airbus&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;RNP&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It may be that some of the issues addressed by the VSD are, for many airports in mountainous terrain, taken care of by &lt;a href=&quot;https://en.wikipedia.org/wiki/Required_navigation_performance&quot; rel=&quot;noreferrer&quot;&gt;RNP (Required Navigation Performance)&lt;/a&gt; which prescribes the required navigational accuracy of the aircraft's navigation systems. Generally the aircraft is required to be able to follow an approach path that consists of a sequence of curved three-dimensional paths to the runway that avoids terrain. I imagine this path is pre-programmed into the navigation systems along with the go-around paths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/noml1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/noml1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-08-28T11:00:56.217" LastActivityDate="2015-08-28T11:00:56.217" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19439" PostTypeId="2" ParentId="19436" CreationDate="2015-08-28T10:26:35.643" Score="4" Body="&lt;p&gt;I'm going to answer this from an aviation safety regulation viewpoint only. There are many broader considerations, such as criminal juristictions, employment, and environmental laws, which will have differing answers. I'll also add that my experience is with the Australian situation, but I don't think it varies too much around the world - happy to be corrected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So with all that considered, the answer is... sort of both! The short answer is that they must follow the direct operating procedures of the country they are flying in, but some &quot;back office&quot; regulations do not apply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly to ICAO. This organisation isn't really concerned about individual airlines. Their primary purpose is to set international standards for the individual regulators to implement. But these Standards and Recommended Practices (SARPs) are not enforceable - individual states can simply lodge a 'difference' and continue to do their own thing. Another important job of ICAOs is to basically regulate the regulator, giving them a rating on how safe they are. The FAA and EASA also conduct their own audits for the same purpose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each airline needs to be certified in its home country with an Air Operators Certificate (or Part 121 Certification, or the many other variants around the world). Part of this process involves approving pretty much every single procedure the aircraft would ever do in normal operations - including the procedures at international ports. That means that for an Australian airline wanting to fly to LAX, the Australian regulator CASA has to inspect the port and approve it for use, checking that what the airline has proposed complies with the local airport procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, once the operations at LAX have been approved by CASA, the airline then approaches the FAA for a Foreign AOC/Part 121 approval etc (I'm not certain of the US naming convention). This certification process for a foreign certificate is almost always no way near as thorough as the full version. A lot of it depends on the home countries regulator and their status with ICAO or the FAA/EASA. If the FAA knows that the oversighting country is up to scratch, issuing the foreign certificate might just be a tick and flick exercise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This 'foreign' status of this approval is key to your question, because many regulations are written like &quot;the Part 121 operator must...&quot; and NOT necessarily &quot;the Foreign Part 121 operator must...&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a breath now and try to follow this. In the majority of occasions, the foreign approval says that the airline must operate in accordance with what has been approved by CASA. But, the procedures which CASA has approved are already tailored to LAX-specific operations! So you can see that the Australian airline has to obey the conditions of its FAA approval, which is to follow the operations set by CASA, which is to follow the US procedures!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what if CASA and the FAA have differing regulations? We do have different requirements for things like fatigue management. Pilots who get a medical clearance here might not get one from the FAA. These 'risks' are pretty much just accepted by the regulators as being extremely unlikely to bring down a plane in their territory given the handful of flights a week they will be making. In extreme circumstances the FAA could place some sort of condition on the approval to further mitigate the risk of differing regulations. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-08-28T10:26:35.643" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19440" PostTypeId="1" AcceptedAnswerId="19449" CreationDate="2015-08-28T11:57:33.433" Score="5" ViewCount="964" Body="&lt;p&gt;The chevrons on a 787 are there exactly to decrease a type of drag that makes the engine louder, but the chevrons form vortices causing more drag. How much thrust is lost from the vortices on the chevrons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KQHtR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KQHtR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1467" LastEditDate="2015-08-28T11:58:48.780" LastActivityDate="2015-08-28T16:41:28.363" Title="How much thrust do you lose by putting chevrons on a engine?" Tags="&lt;airliner&gt;&lt;boeing-787&gt;&lt;chevrons&gt;&lt;boeing-747&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19441" PostTypeId="1" AcceptedAnswerId="19442" CreationDate="2015-08-28T12:03:02.770" Score="-3" ViewCount="291" Body="&lt;p&gt;NASA actually did studies that say that it does increase the thrust. Air moves faster on top of the wing than the bottom, so could this have an effect on the engine's performance if there is more intake of air into the engine if the engine was mounted on top of the wing instead of the bottom?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1961" LastEditDate="2015-11-01T23:37:24.477" LastActivityDate="2015-11-01T23:37:24.477" Title="Would an engine have more thrust if it was mounted on top of the wing?" Tags="&lt;efficiency&gt;&lt;engine-placement&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-08-28T12:57:23.557" ContentLicense="CC BY-SA 3.0" />
  <row Id="19442" PostTypeId="2" ParentId="19441" CreationDate="2015-08-28T12:29:26.350" Score="4" Body="&lt;p&gt;First, we need to agree what thrust is. The simplest definition would be to measure the pressure in the intake and the nozzle, as described in the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/9144/how-is-engine-thrust-measured-in-flight&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this gets you only so far. It would be more complete to use the difference in horizontal forces acting on the plane between idle and full thrust for the definition, because that is really what interests the pilot. Imagine that your engine will cause massive separation around the intake at idle (&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/inleth.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;spill drag&lt;/a&gt;), or that the exhaust jet will help the flow over the deflected flaps to stay attached, avoiding the drag of separated flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we can agree to include the change in drag into our thrust measurement, the next question is what flight segment is used? In cruise, the flow around wings and fuselage is nearly completely attached, and the engine can only spoil the orderly flow. Next, since the speed of flow is higher on the upper side of the wing and the intake needs to decelerate the flow, a top-mounted engine would need to decelerate its intake flow more than one below the wing. This leads to higher intake losses and less net thrust. Conversely, if the engine is below the wing, the wing will already decelerate the flow somewhat before it is ingested by the intake, which makes the work of the intake easier and reduces losses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the landing configuration, however, a deflected flap blown by the engine exhaust will create a much better L/D than one without. In this case, it is better placed on top of the wing. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_YC-14&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing YC-14&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-72&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antonov 72&lt;/a&gt; are examples of such configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the cruise segment is much longer, most designs prefer to place the engines below the wing, but quite a bit ahead of the aerodynamically ideal position to shift the center of gravity of the wing ahead of its axis of elasticity, thereby helping to dampen flutter.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-08-28T12:29:26.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19443" PostTypeId="1" AcceptedAnswerId="20686" CreationDate="2015-08-28T13:05:56.597" Score="16" ViewCount="2472" Body="&lt;p&gt;I'm under the impression that some large craft are rated for &quot;unpaved strips&quot;, which appear to be either some sort of gravel or perhaps dirt.  The 727, and this runway, being a good example of this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CmMbd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CmMbd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;Picture taken from &lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/can-jet-airplanes-operate-on-rough-airfields&quot;&gt;this question&lt;/a&gt;, which is also a good reference on how large airplanes can operate on &quot;rough&quot; fields.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm wondering is how these fields are prepared?  I assume the ground is required to be able to hold up a certain amount of weight, and I also assume that ability &lt;em&gt;must&lt;/em&gt; be uniform, or you'd be risking a wheel poking into the runway and basically ruining everyones day...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do they prepare/create these runways?  And how do they ensure that they maintain the ability to be used for operations with craft that are rated for &quot;unpaved&quot; but probably not rated for &quot;random, somewhat grassy field.&quot;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-04T18:42:57.637" Title="How are unpaved strips created and maintained?" Tags="&lt;runways&gt;&lt;airport-design&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19445" PostTypeId="2" ParentId="19443" CreationDate="2015-08-28T13:43:19.270" Score="6" Body="&lt;p&gt;First off all pilots are trained for &lt;a href=&quot;http://flighttraining.aopa.org/students/maneuvers/skills/shortsoftlanding.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;soft field landings&lt;/a&gt; and I assume the procedures for large craft are not all that different from small craft. The main goal is to keep weight off the nose wheel as much as possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How the field is prepared will depend on where it is geographically. In the desert or other dry hard areas this is not really that hard for obvious reasons. In a grassy area you will need to mow the grass and possibly clear some trees or other low brush. The area of PA I fly in is littered with private grass strips that are hard to differentiate from the fields next to them. Many of them look like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/W4bAH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/W4bAH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the uniformity of the ground beneath them, as far as I know they are not altered in any way. This factor is mainly altered by the weather. If it has just  rained the ground is going to be muddy and slick, possibly not useable. Check out &lt;a href=&quot;https://aviation.stackexchange.com/questions/19313/how-heavy-is-too-heavy-to-land-on-a-grass-strip&quot;&gt;this question&lt;/a&gt; for more info on that.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-08-28T13:43:19.270" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19446" PostTypeId="1" AcceptedAnswerId="27532" CreationDate="2015-08-28T14:07:41.113" Score="31" ViewCount="12663" Body="&lt;p&gt;I noticed that some Mig-29 Fighter Jets have a little mirror-like-thing over the cockpit. I can't imagine a possible usage from it (If it's really a mirror).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a picture from &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/c/cd/Mig-29UB.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3sYWu.jpg&quot; alt=&quot;Mig-29&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see on the following picture, not every Mig-29 has this thing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sSB5P.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sSB5P.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is this &quot;Mirror&quot;-like-thing supposed to do?&lt;/li&gt;&#xA;&lt;li&gt;Why can't I find it on every Mig-29?&lt;/li&gt;&#xA;&lt;li&gt;When is this thing used? In combat, training etc.?&lt;/li&gt;&#xA;&lt;li&gt;How does it help the pilot / trainer in flight?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="15311" LastEditDate="2017-12-24T11:32:01.523" LastActivityDate="2019-02-03T14:04:53.947" Title="What is the purpose of the &quot;Mirror-Thing&quot; over the Mig-29 Cockpit?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;cockpit&gt;&lt;fighter&gt;&lt;mig-29&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19447" PostTypeId="1" AcceptedAnswerId="19465" CreationDate="2015-08-28T14:29:55.480" Score="3" ViewCount="7669" Body="&lt;p&gt;I'm building a quadcopter as my bachelor's degree thesis. I'm having trouble finding a reliable equation for calculating the static thrust for a quadcopter. The equations I have found give me ridiculous results. I know that it's difficult to derive such an equation and I know that there are online calculators (like &lt;a href=&quot;http://www.ecalc.ch/xcoptercalc.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt;). But how do these calculators calculate static thrust? There has to be an approximate equation somewhere. This is what I'm asking. I don't mind the equation(s) that lead me to there, I would just like to know them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: More information&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following snapshot is taken from Mathcad software. It's various equations i have gathered from supposed trustworthy websites. These equations lead me to the calculation of static thrust. I think the equations are pretty self explanatory. Thank you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G5T1A.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G5T1A.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Components of the quadcopter: &lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=7636&quot; rel=&quot;nofollow noreferrer&quot;&gt;Battery&lt;/a&gt;, &lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/__2161__TURNIGY_Plush_12amp_2A_BEC_BESC.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;ESC's&lt;/a&gt;, &lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/__66424__Turnigy_Multistar_1704_2300Kv_12_Pole_Multi_Rotor_Outrunner_V2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Motors&lt;/a&gt;, &lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/__68702__Gemfan_5040_Multirotor_Propellers_One_Pair_CW_CCW_5X4_Green_.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Propellers&lt;/a&gt;, &lt;a href=&quot;http://www.hobbyking.com/hobbyking/store/__56212__HobbyKing_FPV250L_Long_Frame_Quad_Copter_A_Mini_Sized_FPV_Multi_Rotor_kit_.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;frame&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Various useful websites that i've found most equations: &lt;a href=&quot;http://www.rcgroups.com/forums/showthread.php?t=393251&quot; rel=&quot;nofollow noreferrer&quot;&gt;1&lt;/a&gt;, &lt;a href=&quot;https://quadcopterproject.wordpress.com/static-thrust-calculation/&quot; rel=&quot;nofollow noreferrer&quot;&gt;2&lt;/a&gt;, &lt;a href=&quot;http://www.stefanv.com/rcstuff/qf200204.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;3&lt;/a&gt;, &lt;a href=&quot;http://oddcopter.com/2012/02/06/choosing-quadcopter-motors-and-props/&quot; rel=&quot;nofollow noreferrer&quot;&gt;4&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10001" LastEditorUserId="19" LastEditDate="2016-07-11T09:07:02.060" LastActivityDate="2020-04-25T08:38:36.507" Title="What is the equation for calculating static thrust?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;rotorcraft&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19448" PostTypeId="2" ParentId="12832" CreationDate="2015-08-28T16:09:33.043" Score="10" Body="&lt;p&gt;The main purpose of the chevrons in the engines is to reduce the engine noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the civil airliners use high bypass turbofan engines, which produce significant amount of noise especially at high thrust conditions. Aircraft (engine) noise is especially critical during the takeoff and approach phases as it affects the people in the area around the airport and also the ground crew. Reduction of jet noise has been one of the focus areas of civil aircraft manufacturers since the (failed) SST program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cm3UB.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cm3UB.gif&quot; alt=&quot;Sources of Takeoffnoise&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen, the engine noise is perhaps the most important contributer for the total aircraft noise.Thus reduction of engine noise becomes paramount. Most of the high bypass turbofan engines have two flow regions- the central core and the surrounding fan. These regions normally don't mix with each other in the short nozzle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jPjUi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jPjUi.jpg&quot; alt=&quot;GP 7200&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Airbus_Lagard%C3%A8re_-_GP7200_engine_MSN108_(1).JPG#/media/File:Airbus_Lagard%C3%A8re_-_GP7200_engine_MSN108_(1).JPG&quot; rel=&quot;noreferrer&quot;&gt;Airbus Lagardère - GP7200 engine MSN108 (1)&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Dr_Brains&quot; rel=&quot;noreferrer&quot; title=&quot;User:Dr Brains&quot;&gt;Dr Brains&lt;/a&gt; - Own work. Licensed under CC0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The schematic below shows the operation a typical high bypass turbofan engines used in civil airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NNcOe.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NNcOe.png&quot; alt=&quot;Turbofan Operation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Turbofan_operation.svg#/media/File:Turbofan_operation.svg&quot; rel=&quot;noreferrer&quot;&gt;Turbofan operation&lt;/a&gt;&quot; by K. Aainsqatsi - Own work. Licensed under CC BY 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, high bypass ratios reduce noise. The main source of the jet noise is the turbulent mixing of the shear layers in the engine exhaust. These shear layers contain instabilities that lead to highly turbulent vortices that generate the pressure fluctuations responsible for sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LmhiQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LmhiQ.jpg&quot; alt=&quot;Mixing Layer Visualization&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[2012, V. Parezanovic] Source: &lt;a href=&quot;http://www.berndnoack.com/&quot; rel=&quot;noreferrer&quot;&gt;http://www.berndnoack.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the was to reduce noise is to mix the core and bypass gases effectively. NASA carried out research in this area and evaluated a number of different configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oUUFn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oUUFn.jpg&quot; alt=&quot;Chevrons&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: NASA- Innovations in Aeronautics&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These studies revealed that though the lobed mixers reduced noise better, the associated thrust loss was more and the chevrons offered the optimal solution. Two solutions, tabbed and chevrons were then (simulated flight) tested in various configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These test showed that the configuration with chevrons in fan nozzles only caused the least reduction in thrust coefficient. This probably was the reason this was selected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to this, research was carried out in developing systems which would optimize the chevron 'immersion' into the jet flow based on the flight condition. Shape memory alloys activated by heat were developed which would allow for full chevron immersion in jet flow during high thrust requirements (for e.g. during takeoff) and not immersing it during cruise where the thrust efficiency is of greater importance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zQIQP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zQIQP.jpg&quot; alt=&quot;Variable Geometry Chevrons&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Variable geometry chevrons for immersion control (AIAA 2006-2546) (Boeing image)&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-28T16:09:33.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19449" PostTypeId="2" ParentId="19440" CreationDate="2015-08-28T16:41:28.363" Score="4" Body="&lt;p&gt;The main purpose of the Chevrons is the reduction of engine noise. During research into this, NASA tested a number of configurations under simulated flying conditions and measured the nozzle thrust coefficient given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_{T_{r}} = \frac{F^{d}_{g}}{F^{i}_{g}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F^{d}_{g}$ is the measure gross thrust and &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F^{i}_{g}$ is the ideal gross thrust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F^{i}_{g}$ = .{m}$_{c} v_{i,c}$ + .{m}$_{f} v_{i,f}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where .{m}$_{c}$ is mass flow rate of core, .{m}$_{f}$ is mass flow rate of fan and $v_{i,c}$ and $v_{i,f}$ are core and fan ideally expanded jet velocities respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reduction in nozzle thrust coefficient was compared with baseline (no modifications) configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C6Roh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C6Roh.jpg&quot; alt=&quot;Chevron in fan only&quot;&gt;&lt;/a&gt;&#xA;Source: NASA/TM—2000-209948&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The configuration used in engine (Chevrons in the fan and nothing in the nozzle produced the lowest loss of thrust coefficient, 0.18.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the noise reduction was lesser in this configuration compared to the others. Further modifications have been carried out in the chevrons used in production engines (they are rounded, for one). So, the noise reduction has been obviously improved, though the minimal loss of thrust would've been maintained. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: All data from &lt;em&gt;Acoustics and Thrust of Separate-Flow Exhaust Nozzles With Mixing Devices for High-Bypass-Ratio Engines&lt;/em&gt;, Naseem H. Saiyed, Kevin L. Mikkelsen and James E. Bridges, Prepared for Prepared for the&#xA;Sixth Aeroacoustics Conference and Exhibit, Lahaina, Hawaii, June 12–14, 2000&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-28T16:41:28.363" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19451" PostTypeId="1" AcceptedAnswerId="19453" CreationDate="2015-08-28T19:33:57.213" Score="3" ViewCount="6281" Body="&lt;p&gt;I am wondering whether or not it is possible for an air plane to fly through a rainbow, and, if so, does anyone have any pictures or experiences of what you can see? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always been intrigued by this.&lt;/p&gt;&#xA;" OwnerUserId="10007" LastActivityDate="2015-08-28T21:06:28.387" Title="Can Air planes fly through rainbows?" Tags="&lt;commercial-aviation&gt;&lt;general-aviation&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ClosedDate="2015-08-28T22:26:38.557" ContentLicense="CC BY-SA 3.0" />
  <row Id="19453" PostTypeId="2" ParentId="19451" CreationDate="2015-08-28T20:01:27.233" Score="12" Body="&lt;p&gt;A rainbow is created by refraction of sunlight so you have to be in the right position to see it. The effect is only created at some distance. A rainbow that you see from the ground may appear to be in a particular place in the sky. An airplane could fly through that space and it might appear to &lt;em&gt;you&lt;/em&gt; that it is passing through it The occupants of the airplane, however, would not see a rainbow there.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-08-28T20:01:27.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19454" PostTypeId="1" AcceptedAnswerId="19455" CreationDate="2015-08-28T20:39:44.460" Score="13" ViewCount="8210" Body="&lt;p&gt;Since more and more airlines are dropping the 747 for the 777 or equivalent due to fuel efficiency, a theoretical question came to mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do you think is preventing Boeing from creating a 747 twinjet (two engines instead of 4).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know there are probably design/engineering issues associated with such a conversion, but I reckon that if it was done it may increase sales to go up against the A380? Not sure the math as well, but perhaps the engine from the 777 could be used or configured for higher thrust?&lt;/p&gt;&#xA;" OwnerUserId="9567" LastEditorUserId="14897" LastEditDate="2017-05-18T22:27:35.827" LastActivityDate="2017-05-18T23:11:37.453" Title="Can the 747 be re-engined as a twin?" Tags="&lt;aircraft-design&gt;&lt;boeing&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ClosedDate="2015-08-29T13:36:16.337" ContentLicense="CC BY-SA 3.0" />
  <row Id="19455" PostTypeId="2" ParentId="19454" CreationDate="2015-08-28T20:58:59.953" Score="22" Body="&lt;p&gt;Currently, the 777 has engines that have a max thrust of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;115,000 lbf&lt;/a&gt;, for a total of 230,000 lbf of thrust. The 747-8 has engines with a max thrust of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;noreferrer&quot;&gt;66,500 lbf&lt;/a&gt;, each, for a total of 266000. And just to throw in for comparison, the A380, currently has engines each producing &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;noreferrer&quot;&gt;72,000 lbf&lt;/a&gt; of thrust, and a total of 288,000 lbf.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right now the 777 has some of the highest thrust producing engines in commercial service. This does not take into account the extra thrust that is required for engine out issues. With a 2 engine design you have to have enough extra thrust for loss of engine during take-off at max take off weight. Whereas with a 4 engine design, you only have to have enough thrust to account for loss of 1 engine. So for a 747 twin engine aircraft, as a rough estimate you'd need to have each engine produce at least 150,000 lbf of thrust if not more.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="14897" LastEditDate="2017-05-18T23:11:37.453" LastActivityDate="2017-05-18T23:11:37.453" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19456" PostTypeId="2" ParentId="19451" CreationDate="2015-08-28T21:06:28.387" Score="5" Body="&lt;p&gt;Running into a rainbow is hard, whether walking, driving, or flying.  The reason is that rainbows are not objects - they are an optical illusion that only exists in the eye of the observer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trying walking toward a rainbow.  You'll find it moves away, and eventually disappears.  This is one reason why you'll hear people say there's a pot of gold at the end of the rainbow to describe wishful thinking.  You can never get to with end of the rainbow - the more you move, the more it moves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being an optical illusion, it has absolutely no impact on other physical objects.  So if you are on the ground, you could observe an airplane flying through a rainbow that you see.  The pilots on the flight would not see the same rainbow you see, and would not be able to tell that they are flying through the optical illusion you are experiencing. They would, however, encounter the water that is creating the illusion for you.  Fortunately most planes have no problem flying through mist or rain, and thus there is no problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason you rarely see photos of planes flying through rainbows is that few pilots enjoy flying through the weather that creates these illusions, and try to avoid them by flying over or around the situation that would create a rainbow.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2015-08-28T21:06:28.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19457" PostTypeId="1" AcceptedAnswerId="19472" CreationDate="2015-08-28T22:46:21.523" Score="9" ViewCount="5573" Body="&lt;p&gt;On a VFR flight, what frequency should be used to talk to somebody on the ground in USA?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In another word, if I am overflying my house and I would like to talk to the people on the ground, what frequency should I be using? Is it even legal to do something like this? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="64" LastEditDate="2015-08-29T05:45:37.677" LastActivityDate="2015-08-29T15:29:59.503" Title="What frequency should be used for air-to-ground communication other than airport ground operation?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19458" PostTypeId="1" AcceptedAnswerId="19466" CreationDate="2015-08-28T22:59:09.077" Score="6" ViewCount="2508" Body="&lt;p&gt;I am looking at a simulation engine (&lt;a href=&quot;http://jsbsim.sourceforge.net/&quot;&gt;jsbsim&lt;/a&gt;). Their turbine engine simulation requires a function, given by table, of thrust at Mach number and density altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine definitions generated by their &lt;a href=&quot;http://jsbsim.sourceforge.net/aeromatic2.html&quot;&gt;initial configuration generator&lt;/a&gt; and all existing configurations I found use the same function that is based on data for [Rolls-Royce/Snecma Olympus 593]. Since that is a turbo&lt;strong&gt;jet&lt;/strong&gt; with supersonic intake duct that increases performance at transsonic and supersonic speeds, I somehow doubt the function is appropriate for high-bypass turbofans with simple pitot inlet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, the table looks like:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;     |  -10000       0   10000   20000   30000   40000   50000&#xA;-----+--------------------------------------------------------&#xA;0.0  |  1.2600  1.0000  0.7400  0.5340  0.3720  0.2410  0.1490&#xA;0.2  |  1.1710  0.9340  0.6970  0.5060  0.3550  0.2310  0.1430&#xA;0.4  |  1.1500  0.9210  0.6920  0.5060  0.3570  0.2330  0.1450&#xA;0.6  |  1.1810  0.9510  0.7210  0.5320  0.3780  0.2480  0.1540&#xA;0.8  |  1.2580  1.0200  0.7820  0.5820  0.4170  0.2750  0.1700&#xA;1.0  |  1.3690  1.1200  0.8710  0.6510  0.4750  0.3150  0.1950&#xA;1.2  |  1.4850  1.2300  0.9750  0.7440  0.5450  0.3640  0.2250&#xA;1.4  |  1.5941  1.3400  1.0860  0.8450  0.6280  0.4240  0.2630&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;where rows are Mach number, columns are density altitude in feet and the values are fractions of rated thrust at zero speed at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust decreases with altitude, which is OK. But with Mach number it only decreases initially and at M0.8 it is already more than static thrust. I had the impression that this requires high exhaust speed and therefore isn't, and can't, be true for turbofans with their low exhaust speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'd like to know whether:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;how appropriate or inappropriate those values are for high-bypass turbofans, especially the recent types with bypass ratio up to 11:1 and&lt;/li&gt;&#xA;&lt;li&gt;where I could get any better data.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I understand the actual data for new engines will be proprietary. I just hope to do better than using data for old and very different engine designed for different operating range.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="64" LastEditDate="2016-07-07T21:05:31.290" LastActivityDate="2016-07-07T21:05:31.290" Title="How does turbofan engine performance depend on speed and density altutude?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19460" PostTypeId="2" ParentId="18865" CreationDate="2015-08-29T02:01:56.530" Score="43" Body="&lt;p&gt;Just spoke to the farmer that owns Graham Farms Airport (SN72), a grass strip in a cornfield near the sprawling metropolis of Harris, Kansas. Here it is on the sectional:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/k9eDH.jpg&quot; alt=&quot;Google Earth&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And Google Earth:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/57Iu1.jpg&quot; alt=&quot;Google Earth&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He has a Cessna 182 there. He told me he had it registered as an airport back in the 1970's, like Dave said, in case someone had an engine failure or something, atc could vector them there. He also occasionally allows people from nearby Garnett Municipal Airport (K68) to practice grass strip landings there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He got an unexpected benefit from having it registered with the FAA several years back when the power company was planning to run a high tension line right across his landing strip. The power company refused to work with him on it so he called the FAA. Since it is officially an airport federal regulations forced them to run their line around it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/rN4aM.jpg&quot; alt=&quot;Picture showing power line path&quot;&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation trumps power company profits!&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="2171" LastEditDate="2015-08-29T02:08:37.237" LastActivityDate="2015-08-29T02:08:37.237" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19461" PostTypeId="1" AcceptedAnswerId="19471" CreationDate="2015-08-29T04:12:31.147" Score="2" ViewCount="574" Body="&lt;p&gt;In a scene from &lt;a href=&quot;https://en.wikipedia.org/wiki/Spider-Man_2&quot; rel=&quot;nofollow&quot;&gt;Spider-Man 2 (2014)&lt;/a&gt;, which you can see in &lt;a href=&quot;https://www.youtube.com/watch?v=xW7aiIfwx1I&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt;, two jumbos almost collided. At the last possible moment, the pilots were able to save their planes, but both planes came to within 100 feet apart from each other (I guessed the distance). Both planes survived.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder in real life with real science and no Hollywood involvement, could any plane survive this close encounter with another jet? &lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="62" LastEditDate="2015-09-01T18:35:58.060" LastActivityDate="2015-09-01T18:35:58.060" Title="Would turbulence created by two jumbos less than 100ft apart cause both of them to crash?" Tags="&lt;safety&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19462" PostTypeId="1" AcceptedAnswerId="19463" CreationDate="2015-08-29T04:53:10.057" Score="-1" ViewCount="202" Body="&lt;p&gt;Lockheed Martin &lt;strong&gt;C-130J&lt;/strong&gt; Super&#xA;Hercules&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing &lt;strong&gt;C-17&lt;/strong&gt; Globemaster III&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cessna &lt;strong&gt;C172&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike A and B, why is C used by various manufacturers? Are there any copyrights for such alphabets used in aircraft model name?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-08-29T10:20:56.507" Title="Why is the C-xx aircraft series used by multiple manufacturers?" Tags="&lt;aircraft-manufacturer&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19463" PostTypeId="2" ParentId="19462" CreationDate="2015-08-29T05:41:11.093" Score="10" Body="&lt;p&gt;Trademark law is a tricky thing: Two companies can use the same mark (name) as long as they are in different areas of business - like Apple (the computer company) &amp;amp; Apple (the  record label that published The Beatles) (which got &lt;em&gt;incredibly&lt;/em&gt; complicated when iTunes happened and the computer company entered the music business).&lt;br&gt;&#xA;Even within the same business area commonly-used names can overlap. A good example of this is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_140&quot;&gt;Cessna 140&lt;/a&gt; and Piper's &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot;&gt;Cherokee 140&lt;/a&gt;: they're both referred to as &quot;a 140&quot; in their respective pilot communities, but their manufacturer model numbers are different (Cessna's model number is &lt;code&gt;140&lt;/code&gt;/&lt;code&gt;140A&lt;/code&gt;, Piper's is &lt;code&gt;PA-28 140&lt;/code&gt;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;None of that applies in this case though, because the names you're looking at don't come from the manufacturer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;code&gt;C&lt;/code&gt; in US military aircraft models (C-130, C-17, C-5, etc.) specifies it as a Cargo aircraft (Similarly &lt;code&gt;F&lt;/code&gt; is used for fighters, &lt;code&gt;A&lt;/code&gt; for attack aircraft, and &lt;code&gt;B&lt;/code&gt; for bombers).  Combined designations also exist (e.g. the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_AC-130&quot;&gt;&lt;code&gt;AC-130&lt;/code&gt; Spectre&lt;/a&gt;, a Lockheed C-130, which is subsequently converted to a weapons platform by Boeing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft designations in these cases are assigned by the military, not the manufacturer, and they may not match the manufacturer's designation (though for aircraft designed exclusively for military service they may).&lt;br&gt;&#xA; Several manufacturers produce aircraft in each category (e.g. the F-14 was a Grumman aircraft, while the F-16 is made by Lockheed/General Dynamics), and many manufacturers produce aircraft in multiple categories (Lockheed for example).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The US Military Trainer version of the Cessna 172 is designated as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_T-41_Mescalero&quot;&gt;T-41 Mescalero&lt;/a&gt;, but it is clearly recognizable as a (mostly-standard) Cessna 172.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The use of &lt;code&gt;C172&lt;/code&gt; for the Cessna 172 is also not the manufacturer's model designation: It is the &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_ICAO_aircraft_type_designators&quot;&gt;ATC aircraft type code&lt;/a&gt; and is used as a matter of convenience when talking about a generic aircraft (e.g. &quot;Your typical Cessna 172&quot;). Cessna light aircraft models are generally designated by the family number (150, 152, 162, 172, 182...) and a variant letter or letters (&lt;code&gt;172S&lt;/code&gt;, &lt;code&gt;172RG&lt;/code&gt;, etc.), which indicate a specific set of aircraft within the general 172 family that share some common characteristics.  &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-29T05:41:11.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19464" PostTypeId="2" ParentId="19458" CreationDate="2015-08-29T05:51:24.067" Score="3" Body="&lt;p&gt;Your impression seems to be right based on one source I could find:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;For high bypass turbofans the thrust seems to monotonically fall with increasing Mach numbers&lt;/li&gt;&#xA;&lt;li&gt;For low bypass turbofans the thrust falls initially but then rises again with Mach number increase&lt;/li&gt;&#xA;&lt;li&gt;For both engines the Thrust falls with increasing altitude&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;See plots below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing you could do is to use empirical equations to scale up the ground level, at rest thrust to various altitudes and Mach numbers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Uy4lC.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uy4lC.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;High bypass Turbofan&lt;/strong&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/omiWx.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/omiWx.png&quot; alt=&quot;High bypass Turbofan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low bypass Turbofans&lt;/strong&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zDfIi.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zDfIi.png&quot; alt=&quot;Low bypass Turbofans&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-08-29T06:12:55.977" LastActivityDate="2015-08-29T06:12:55.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19465" PostTypeId="2" ParentId="19447" CreationDate="2015-08-29T06:48:28.410" Score="3" Body="&lt;p&gt;By now you should have found &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;this answer on static thrust&lt;/a&gt;. It explains how to arrive at this equation for static thrust $T_0$:&#xA; $$T_0 = \sqrt[3]{P^2\cdot\eta_{Prop}^2\cdot\eta_{el}^2\cdot\pi\cdot \frac{d_P^2}{2}\cdot\rho}$$&#xA;Your P is at most 11.1 V × 4.5 A = 49.95&amp;nbsp;W. Your prop efficiency $\eta_{Prop}$ must be guessed; let's take 60%. The electric efficiency should be higher; let's use 95% for now. The prop diameter $d_P$ is 3 or 5&amp;nbsp;inches (depends if your comments or the picture in your question is more reliable), so I use 0.127&amp;nbsp;m for now. Air density is given with 1.18&amp;nbsp;kg/m³.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I plug in the numbers, I get 2.894&amp;nbsp;N. One propeller can lift approximately 295&amp;nbsp;g of quadcopter, and all four will produce thrust equivalent to the weight of 1.18&amp;nbsp;kg in Earth's gravitation. Looks about right for a quadcopter of 500&amp;nbsp;g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't assume that the motor delivers all the power the propeller can absorb. Also, don't assume that the RPM of the isolated motor can be maintained when it is driving a propeller.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-08-29T18:08:25.267" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19466" PostTypeId="2" ParentId="19458" CreationDate="2015-08-29T07:18:33.087" Score="4" Body="&lt;p&gt;The dependence on density is straightforward: Thrust depends on the mass of air pushed out at the back, and this is changing linearly with density if the speeds don't change.&#xA;$$T \propto \frac{1}{\rho}$$&#xA;The dependency on speed has two factors, the intake precompression and the speed difference between flight speed and exhaust speed. First intake precompression:&#xA;$$T \propto \left(\frac{\kappa-1}{2}\cdot Ma^2\cdot\left(1-\left(\frac{Ma_{intake}}{Ma_{\infty}}\right)^2\right) + 1\right)^{\frac{\kappa}{\kappa-1}}$$&#xA;or, if we insert $\kappa = 1.405$ for diatomic gasses:&#xA;$$T \propto \left(0.2025\cdot Ma^2 \cdot\left(1-\left(\frac{Ma_{intake}}{Ma_{\infty}}\right)^2\right) + 1\right)^{3.469}$$&#xA;The term which captures the thrust proportionality to the speed difference looks like this:&#xA;$$T \propto \frac{v_{nozzle} - v_{\infty}}{v_{nozzle}}$$&#xA;Please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717#14717&quot;&gt;this answer&lt;/a&gt; for an explanation of the variables. The plot below shows how little the intake precompression matters at subsonic speed, but how much it does at higher Mach numbers. Note that the plot sets the pressure at the engine face to 1 when flight speed equals the assumed intake speed of Mach 0.5. This pressure recovery lets thrust climb above the static value once Concorde flies supersonic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/dtaIi.png&quot; alt=&quot;pressure recovery ratio over Mach number&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Explanation of the plot: This shows relative ideal intake pressure over speed, assuming that the speed at the compressor face is Mach 0.5. Note that in static conditions the air needs to be accelerated, so the intake pressure is only 84% of ambient pressure, and at Mach 0.85, the maximum speed of airliners, the intake pressure is 1.37 times higher than ambient pressure. But at supersonic speed things take really off: Pressure recovery for the Concorde was already 6 at Mach 2.0, and for the SR-71 it was 40 at Mach 3.2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the engine has no variable nozzle, it is fair to assume that the nozzle speed will not change over the flight speed if the throttle setting is constant. If the nozzle speed is low (= high bypass ratio), the drop over speed is steeper, which explains the difference between turbojets and turbofans.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-04T09:09:17.113" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="19467" PostTypeId="2" ParentId="19461" CreationDate="2015-08-29T09:00:48.987" Score="2" Body="&lt;p&gt;Wake turbulence is a serious problem if flying too close to another aircraft, for example if a light aircraft follows a larger aircraft, the sheer amount of air and wind speeds involved could cause a loss of control and possible subsequent damage to the aircraft if not rated for aerobatics (or if close to the ground). You have to stay quite a long way behind a larger aircraft when approaching to land to be sure of not encountering it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if encountering wake turbulence from an aircraft of a similar size, while you would most definitely feel it, I don't think it would cause a loss of control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even so, when flying in formation aircraft stay away from the others wake turbulence because although I don't think it would cause them to crash it would be uncomfortable and the formation wouldn't look smooth if at an airshow for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the other part of your question - would it affect the aircraft in front? Only if the aircraft behind lost control and hit it, as was thought to happen to Joe Walker who was flying a F104 and hit the aircraft he was chasing causing both to go down &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/fCORwUxlNQo?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;, it was suspected that the F104 was caught wake turbulence from the large aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-08-29T11:26:55.503" LastActivityDate="2015-08-29T11:26:55.503" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19468" PostTypeId="2" ParentId="19462" CreationDate="2015-08-29T10:20:56.507" Score="2" Body="&lt;p&gt;The reason 'C' is in the names of C-17 Globemaster III and C-130J Super Hercules is because US DoD follws the &lt;a href=&quot;http://www.dtic.mil/whs/directives/corres/pdf/412015l.pdf&quot; rel=&quot;nofollow&quot;&gt;1962 United States Tri-Service aircraft designation system&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per this system, all aircrafts are assigned a Basic mission code, here 'C' for Cargo(Transport). This is given by the DoD and bears no resemblance to the civil aircraft (Company) name.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the USAF and US Army operate a variant of Cessna 172, which is called &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_T-41_Mescalero&quot; rel=&quot;nofollow&quot;&gt;T-41 Mescalero&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cessna 172 may be called C172 by some users, thought there is no 'official' name as such for the Cessna 172 Skyhawk. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-29T10:20:56.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19469" PostTypeId="2" ParentId="19454" CreationDate="2015-08-29T12:50:39.590" Score="5" Body="&lt;p&gt;For a wing design it's better to have more engines because the loads evenly spread along the wing. This allows a lighter wing design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition you must provide a minimum yaw control ability at one engine in-operating during take-off. This means you have to enlarge the vertical stabilizer. This enlarges the drag during normal operation. &lt;/p&gt;&#xA;" OwnerUserId="10015" LastActivityDate="2015-08-29T12:50:39.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19470" PostTypeId="1" AcceptedAnswerId="19474" CreationDate="2015-08-29T13:02:22.327" Score="-4" ViewCount="253" Body="&lt;p&gt;I know that the swept wing decreases lift and the winglet increases lift. Is it better to have a winglet or a swept wing.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-08-29T15:46:41.840" Title="Is a swept wing the better option against the winglet" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-08-29T16:24:08.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="19471" PostTypeId="2" ParentId="19461" CreationDate="2015-08-29T14:22:17.247" Score="5" Body="&lt;p&gt;The probability of two jets surviving such a close encounter are extremely remote.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Setting aside the fact that it is difficult to imagine two aircraft flying in the same altitude in opposite directions (commercial aircraft are separated by 3 miles laterally and 1000 ft. vertically) ,if the scenario unfolds as in the movie and the horizontal separation between the aircraft on approach is as shown, the pilots would not have time to react and take the necessary evasive actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that the jets are cruising towards each other at 900 kmph, the combined speed is around 1800 kmph, or half a kilometer per second.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the TCAS is not working and the aircraft come within five km (the distance in the video is considerably lower, less than a km) of each other, the pilots have less than 10 seconds to get out of each other's way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The civil aircrafts are not designed for such rapid roll rates. The inertia of the aircraft (especially the 747) will limit it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing to note is that the modern flight control systems will not allow airline pilots to carry the maneuvers shown in the flight. The pilot can override the Flight control Computer.However,in this case, they would not have time to react.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If by some miracle the aircrafts cross each other, they will fly right into the other aircraft's wake turbulence, which will have disastrous consequences, especially for the smaller aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pEdJp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pEdJp.jpg&quot; alt=&quot;Effect of Vortices&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Sources: airpower.maxwell.af&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of small aircraft flying behind a heavy jet, FAA regulations require a minimum separation of 5 miles, lesser than which the effect of the wake turbulence (wingtip vortices) can have serious consequences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mOYPf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mOYPf.png&quot; alt=&quot;AIM&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: Aeronautical Information Manual&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA conducted &lt;a href=&quot;https://www.youtube.com/watch?v=s6K1ArSyiuI&quot; rel=&quot;nofollow noreferrer&quot;&gt;a test&lt;/a&gt; on the effects of wake turbulence by flying a 737 behind a 727, which shows the loss of control associated with flying in the wake of another aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once (if) the aircraft pass each other, they should be brought to level flight as quickly as possible (whether it is possible or not is another question) to prevent stall. In this critical juncture, if the aircraft wings encounter wake turbulence, the control of the aircraft will be loss, resulting in stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, in case two aircraft do approach each other in the same altitude in opposite directions, there are laid down procedures to follow. None of them involve the stunt shown in the movie.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When two aircraft are flying head on, each must move to their right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hZYyy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hZYyy.jpg&quot; alt=&quot;Head On&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: planefinder.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If two aircraft are at the same height and on converging courses, the aircraft with the other on its starboard side has to give way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FkThW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FkThW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: planefinder.net&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-31T13:08:34.400" LastActivityDate="2015-08-31T13:08:34.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19472" PostTypeId="2" ParentId="19457" CreationDate="2015-08-29T14:37:45.460" Score="6" Body="&lt;p&gt;Radio frequencies in the USA are assigned by the &lt;a href=&quot;https://www.fcc.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FCC&lt;/a&gt;, not the FAA. There's no 'private' air-to-ground frequency mentioned in the AIM but &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;section 4-1-11&lt;/a&gt; does say that the FCC has assigned 122.900 as a MULTICOM frequency for:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Activities of a temporary, seasonal, emergency nature or search and&#xA;  rescue, as well as, airports with no tower, FSS, or UNICOM&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Arguably your fly-by is &quot;temporary activity&quot;, however the definition of MULTICOM is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A mobile service not open to public correspondence used to provide&#xA;  communications essential to  conduct the activities being performed by&#xA;  or directed from private aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if your fly-by is &quot;essential&quot; (and safe!) then I guess you could use 122.9. There are &lt;a href=&quot;https://www.faa.gov/about/initiatives/airshow/media/Air_Show_Freq_Request_Guidance.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;procedures&lt;/a&gt; for requesting temporary air-to-ground frequencies for air shows, but that's obviously a special case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for legality, it seems that &lt;a href=&quot;http://wireless.fcc.gov/services/index.htm?job=operations&amp;amp;id=aircraft_stations&quot; rel=&quot;nofollow noreferrer&quot;&gt;you need an FCC license&lt;/a&gt; to use an aviation handheld radio on the ground:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You may only use your hand-held aircraft VHF radio in your aircraft&#xA;  under the terms of your aircraft license. You are required to have a&#xA;  separate Ground Station license to operate your radio on the ground.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But because this is more about FCC regulations than FAA ones, I suggest that you ask on &lt;a href=&quot;https://ham.stackexchange.com/&quot;&gt;ham.SE&lt;/a&gt;; they'll probably know a lot more about how it all works.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:20.767" LastActivityDate="2015-08-29T14:37:45.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19473" PostTypeId="2" ParentId="19457" CreationDate="2015-08-29T15:29:59.503" Score="-1" Body="&lt;p&gt;Some people use &quot;fingers&quot; 123.45 for non-standard radio communications. I don't think it conflicts with any existing radio stations and its legality is in in doubt. Sometimes you will hear on a busy frequency &quot;BOB! FINGERS&quot; which is never acknowledge either by the intended recipient or by ATC, but it means t come up on 123.45&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-08-29T15:29:59.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19474" PostTypeId="2" ParentId="19470" CreationDate="2015-08-29T15:46:41.840" Score="3" Body="&lt;p&gt;Both ideas are dealing with different physical phenomena, so there is no &quot;better or worse&quot; as they are, actually, sometime complementary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swept wing is used in high subsonic (Mach &gt; 0.7) airplanes, and the idea is to reduce the effective incidence Mach on the airfoil, reducing the negative effect of compressibility on the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the winglet tries to reduce the negative effect of having a finite wing as the air in the tail generates a vortex which increase resistance. In summary reduces what is called &quot;induced drag&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So... low subsonic airplanes might have winglet and not a swept wing (notice that this one is trapezoidal):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OOtfg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OOtfg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2015-08-29T15:46:41.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19475" PostTypeId="1" AcceptedAnswerId="19477" CreationDate="2015-08-29T16:02:27.437" Score="19" ViewCount="67525" Body="&lt;p&gt;I remember reading that there are four common wing planforms:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rectangular&lt;/li&gt;&#xA;&lt;li&gt;Eliptical&lt;/li&gt;&#xA;&lt;li&gt;Tapered&lt;/li&gt;&#xA;&lt;li&gt;Sweptback&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are more. What are the different types of planform out there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each must have its own advantages and disadvantages. What are those?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's a good example of each?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2018-02-02T17:00:41.823" Title="What are the different wing planforms? What are each's advantages? Where are they commonly used?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19476" PostTypeId="2" ParentId="19475" CreationDate="2015-08-29T16:29:32.220" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://history.nasa.gov/SP-367/f13b.htm&quot; rel=&quot;nofollow&quot;&gt;Here&lt;/a&gt; is a pictorial list of planforms.  The different planforms are designed to produce the highest &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift-to-drag_ratio&quot; rel=&quot;nofollow&quot;&gt;lift:drag ratio&lt;/a&gt; at various speeds while still being producible.  Swept and delta wings are for speeds &lt;a href=&quot;https://en.wikipedia.org/wiki/Transonic&quot; rel=&quot;nofollow&quot;&gt;approaching&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Supersonic_speed&quot; rel=&quot;nofollow&quot;&gt;exceeding&lt;/a&gt; the speed of sound.  Elliptical, tapered, and rectangular are for subsonic speeds.  At these speeds, the major issue is &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift-induced_drag&quot; rel=&quot;nofollow&quot;&gt;induced drag&lt;/a&gt;.  The rectangular wing is the easiest to build.  The elliptical wing has the lowest induced drag.  Tapered is a compromise between the two.  There are other factors such as stall behavior that influence choice of planform.  Too much taper and a stall at the tips can result in a spin.  The link &lt;a href=&quot;http://www.dauntless-soft.com/PRODUCTS/Freebies/Library/books/FLT/Chapter17/WingPlanform.htm&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; has more.  &lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-08-29T16:29:32.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19477" PostTypeId="2" ParentId="19475" CreationDate="2015-08-29T18:11:27.863" Score="46" Body="&lt;p&gt;The wing planform (which is the shape and layout of wing) for each aircraft is mainly based on the aerodynamic requirements. There are other considerations like stealth, controllability etc. The basic terminology in the wing geometry is given in the figure below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vZbSP.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vZbSP.gif&quot; alt=&quot;Wing Geometry&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: grc.nasa.gov&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the wing platforms in use (or have been used) fall under one of these categories. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Elliptical&lt;/strong&gt; Aerodynamically, the elliptical planform is the most efficient as elliptical spanwise lift distribution has the lowest possible induced drag (as given by thin airfoil theory). However, the most important disadvantage of the elliptical wing is that its manufacturability is poor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the most famous aircraft with elliptical planform is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire&quot; rel=&quot;noreferrer&quot;&gt;Supermarine Spitfire&lt;/a&gt;, used in Battle of Britan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/POS6W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/POS6W.jpg&quot; alt=&quot;Supermarine Spitfire&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Spitfire_mark19_ps853_planform_arp.jpg#/media/File:Spitfire_mark19_ps853_planform_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;Spitfire mark19 ps853 planform arp&lt;/a&gt;&quot; by Adrian Pingstone (&lt;a href=&quot;//commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;noreferrer&quot; title=&quot;User:Arpingstone&quot;&gt;Arpingstone&lt;/a&gt;) - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the elliptical wing was not decided to minimize induced drag, but to house the retractable landing gear along with guns and ammunition inside a wing that had to be thin. As per designer Beverly Shenstone,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ellipse was simply the shape that allowed us the thinnest possible wing with room inside to carry the necessary structure and the things we wanted to cram in. And it looked nice.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Seversky_P-35&quot; rel=&quot;noreferrer&quot;&gt;Seversky P-35&lt;/a&gt; had a semi elliptical wing, with only the leading or trailing edge elliptical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nrvsB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nrvsB.jpg&quot; alt=&quot;Seversky P 35&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Seversky_SEV-DS.jpg#/media/File:Seversky_SEV-DS.jpg&quot; rel=&quot;noreferrer&quot;&gt;Seversky SEV-DS&lt;/a&gt;&quot; by Unknown - &lt;a href=&quot;http://www.flickr.com/photos/sdasmarchives/8392339249/in/set-72157631292290354&quot; rel=&quot;noreferrer&quot;&gt;http://www.flickr.com/photos/sdasmarchives/8392339249/in/set-72157631292290354&lt;/a&gt;. Licensed under CC0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Rectangular&lt;/strong&gt; Arguably the simplest wing planform from a manufacturing point of view, the rectangular wing is a straight, untapered wing. A good example would be the light general aircraft like &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-38_Tomahawk&quot; rel=&quot;noreferrer&quot;&gt;Piper PA 38&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CUZmz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CUZmz.jpg&quot; alt=&quot;Piper PA 38&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Piper_pa-38-112_g-bppf_arp.jpg#/media/File:Piper_pa-38-112_g-bppf_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;Piper pa-38-112 g-bppf arp&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantage of this wing is that it is aerodynamically inefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tapered Wing&lt;/strong&gt; This is a modification of the rectangular wing where the chord is varied across the span to approximate the elliptical lift distribution. While not as efficient as the elliptical lift distribution, it offers a compromise between manufacturability and efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very good example of aircraft using this type of wing is the North American &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot; rel=&quot;noreferrer&quot;&gt;P-51 Mustang&lt;/a&gt;, which became the premier USAAF escort fighter against the Luftwaffe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tFNRr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tFNRr.jpg&quot; alt=&quot;North American P-51 Mustang&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:P51-d_mustang_472216_arp.jpg#/media/File:P51-d_mustang_472216_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;P51-d mustang 472216 arp&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Constant Chord with Tapered Outer&lt;/strong&gt; This is midway between the rectangular and the tapered wing, with the inner part having constant chord and the outer part having a taper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very good example of this type of wing is the &lt;a href=&quot;https://en.wikipedia.org/wiki/English_Electric_Canberra&quot; rel=&quot;noreferrer&quot;&gt;English Electric Canberra&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U1qPc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U1qPc.jpg&quot; alt=&quot;English Electric Canberra&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all of the wings seen so far are used in subsonic aircraft due to the large drag caused by them in the transonic regime. Most of the wings used in supersonic aircraft fall under one of the following categories.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Delta&lt;/strong&gt; The delta is a very low aspect ratio wing used in supersonic aircraft, most notably in the European designs. The main advantages of the delta wing is that is efficient in all the flight regimes (subsonic, transonic and supersonic). Also, the wing offers a large wing area for the shape, reducing wing loading and improving maneuverability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The delta wing design is also very strong structurally, offering large volume for internal fuel. The delta wings are also quite simple to build and maintain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantages are that they have high induced drag due to low aspect ratio and also that they should have high angle of attack at low speeds (takeoff and landing), mainly due to fact that at these speeds, lift is generated by vortices. To compensate for this, they have high stall angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very good example for this wing is the Dassault &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Mirage_2000&quot; rel=&quot;noreferrer&quot;&gt;Mirage 2000&lt;/a&gt;, which is an example of tailless delta i.e. without horizontal stabilizers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wMOHM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wMOHM.jpg&quot; alt=&quot;Mirage 2000F&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.aircraftrecognition.co.uk&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A variant of the delta wing used in some aircraft is the one with horizontal stabilizer (tailed delta), the most famous of them being the Russian &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21&quot; rel=&quot;noreferrer&quot;&gt;Mikoyan-Gurevich MiG-21&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mYG1l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mYG1l.jpg&quot; alt=&quot;Mikoyan Grevich Mig 21&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: hdwallpapers.cat&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another variant is the one used by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt;, the so called cropped delta, where the tips of the delta are 'cut off' to reduce drag at high angles of attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ROa8j.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ROa8j.jpg&quot; alt=&quot;Eurofighter Typhoon&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Eurofighter_9803_2.jpg#/media/File:Eurofighter_9803_2.jpg&quot; rel=&quot;noreferrer&quot;&gt;Eurofighter 9803 2&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Kogo&quot; rel=&quot;noreferrer&quot; title=&quot;User:Kogo&quot;&gt;Kogo&lt;/a&gt; - Own work. Licensed under GFDL via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet another variant of the delta wing (this planform is very popular in combat aircraft), is the so called double delta, where the leading edge angle is not constant, but has two different values. One good example of this is the &lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;noreferrer&quot;&gt;Light Combat Aircraft&lt;/a&gt; 'Tejas' under development in India.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XrwoN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XrwoN.jpg&quot; alt=&quot;LCA Tejas&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:LCA_Tejas.jpg#/media/File:LCA_Tejas.jpg&quot; rel=&quot;noreferrer&quot;&gt;LCA Tejas&lt;/a&gt;&quot; by Rinju9 - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Trapezoidal&lt;/strong&gt; The trapezoidal wing is a high performance configuration such that the leading edge sweeps back and the trailing edge sweeps forward. This is mostly found in combat aircraft from the US. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This wing configuration offers efficient supersonic flight and has very good stealth characteristics. However, the wing loading is quite high, resulting in reduced maneuverability, especially instantaneous turn rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This wing configuration is used most notably in the Lockheed Martin F-22 Raptor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0QYwN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0QYwN.jpg&quot; alt=&quot;Lockheed Martin F-22 Raptor&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F_22_raptor_bomb_bay_display_2014_Reno_Air_Races_photo_D_Ramey_Logan.jpg#/media/File:F_22_raptor_bomb_bay_display_2014_Reno_Air_Races_photo_D_Ramey_Logan.jpg&quot; rel=&quot;noreferrer&quot;&gt;F 22 raptor bomb bay display 2014 Reno Air Races photo D Ramey Logan&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:WPPilot&quot; rel=&quot;noreferrer&quot; title=&quot;User:WPPilot&quot;&gt;WPPilot&lt;/a&gt; - Own work. Licensed under CC BY-SA 4.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Ogive&lt;/strong&gt; The Ogive is a type of supersonic wing used in high speed aircraft. This is a complex mathematical shape derived for minimizing drag, especially at supersonic speeds. They offer excellent supersonic performance, with minimal drag. However, they are extremely complex and manufacturing is difficult while their subsonic performance is poor in comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important aircraft using this wing is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Aérospatiale-BAC Concorde&lt;/a&gt;, one of the two supersonic commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ucdWl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ucdWl.jpg&quot; alt=&quot;Concorde&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.wired.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing planforms can also be classified on their sweep and variability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Swept Back wings&lt;/strong&gt; The leading edges of these wings are swept back. This is done order to reduce drag in transonic speeds, which is determined by the velocity normal to the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This planform is used in almost all high speed commercial airliners. A good example would be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;noreferrer&quot;&gt;Boeing 787 Dreamliner&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1OUtR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1OUtR.jpg&quot; alt=&quot;Boeing 787 Dreamliner&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Boeing_787-8_Dreamliner_N787FT_KBFI.jpg#/media/File:Boeing_787-8_Dreamliner_N787FT_KBFI.jpg&quot; rel=&quot;noreferrer&quot;&gt;Boeing 787-8 Dreamliner N787FT KBFI&lt;/a&gt;&quot; by redlegsfan21 - Flickr: N787FT. Licensed under CC BY-SA 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Swept Forward Wings&lt;/strong&gt; One disadvantage of the swept back wings is that due to the flow characteristics, the ailerons stall before the flaps (i.e. outboard wings stall first), which can lead to controllability issues. In order to overcome this, swept forward wings were used  in a few (experimental) aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The man problem with swept forward wing is that it produces wing twisting as it bends under load, resulting in greater stress on the wing root than for a similar straight or swept back wing. One of the few aircraft to use this wing is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-47&quot; rel=&quot;noreferrer&quot;&gt;Sukoi Su-47 Berkut&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yf5jH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yf5jH.jpg&quot; alt=&quot;Sukoi Su 47&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: tom-clancys-hawx.wikia.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Variable Sweep Wings&lt;/strong&gt; For high speeds (transonic and supersonic), the swept wing is most suitable while for low speed (subsonic) flight, unswept wings are better. Varaible sweep wings were used to optimize the wing planform over a wide range of speeds. The main problem with this type of wing is the mechanical complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first aircraft to enter service with the variable sweep wing was the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;General Dynamics F-111 Aardvak&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ncBlb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ncBlb.jpg&quot; alt=&quot;F-111 Aardvak&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:F-111A_Wing_Sweep_Sequence.jpg#/media/File:F-111A_Wing_Sweep_Sequence.jpg&quot; rel=&quot;noreferrer&quot;&gt;F-111A Wing Sweep Sequence&lt;/a&gt;&quot; by Unknown. - &lt;a href=&quot;http://www.nationalmuseum.af.mil/factsheets/factsheet_media.asp?fsID=2321&amp;amp;page=3&quot; rel=&quot;noreferrer&quot;&gt;http://www.nationalmuseum.af.mil/factsheets/factsheet_media.asp?fsID=2321&amp;amp;page=3&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;//en.wikipedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though most of the aircraft have used these planform, a number of other wing shapes have also been tried.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_Victor&quot; rel=&quot;noreferrer&quot;&gt;Handley Page Victor&lt;/a&gt; used a Crescent shaped wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xqSWy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xqSWy.jpg&quot; alt=&quot;Handley Page Victor&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 XL used a cranked-arrow double delta wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/skbgr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/skbgr.jpg&quot; alt=&quot;F-16 XL&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.nasa.gov&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One point to note is that most of the aircraft in operation or development use wing planforms which are a combination of the above rather than any one of them.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-08-31T15:07:17.787" LastActivityDate="2015-08-31T15:07:17.787" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19478" PostTypeId="1" AcceptedAnswerId="19532" CreationDate="2015-08-29T19:12:53.713" Score="6" ViewCount="1970" Body="&lt;p&gt;&lt;em&gt;Revision 3. Clarifications, as required by moderators, added. The main reason for asking the question provided.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Regarding the reverse command regime of a plane&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming a plane hovers (ground speed $V_{g,1}=0)$ against a headwind with a velocity $V_{w,1}$, is it possible for this plane to start moving ($V_{g,2}$ &gt; 0) just because the wind intensifies increasing its speed from $V_{w,1}$ to $V_{w,2}$ &gt; $V_{w,1}$?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is known that once the plane hovers against the $V_{w,1}$ wind all its control surfaces and the power delivered to the propeller remain locked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a further clarification, the plane is not restricted to always stay at the same altitude. It can rise. However the power must remain unchanged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, I am interested to find out if a plane can fly faster and faster as the headwind speed increases in the particular case the plane is in the reverse command regime (see definition: &lt;a href=&quot;http://aviationglossary.com/region-of-reverse-command/&quot;&gt;http://aviationglossary.com/region-of-reverse-command/&lt;/a&gt; ). For the direct command regime I understand that this behavior is not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why do I ask this apparently strange question?&lt;/strong&gt; Because it appears that a plane, in certain conditions which are not clear for me, can gain some ground speed only from the intensity of the headwind, as long as two aviation pioneers noticed this effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1904, the Wright Brothers started to test a new plane, Flyer II, somewhere near Dayton, Ohio where they managed to get permission to use a flat pasture for their experiments. The winds were light there and, in the beginning, they had no catapult to quickly accelerate their machine and throw it into the air. They simply started the engine of the airplane which began to move along a track (a runway) while a headwind of moderate intensity was blowing and finally they got into the air and flew slower if the headwind speed was lower and faster if the headwind was stronger (see letters 1 and 2).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Letter 1&lt;/strong&gt;:&#xA;Fragment from a letter addressed by Wilbur Wright to Octave Chanute, on August 8, 1904: &#xA;&quot;&lt;em&gt;One of the Saturday flights reached 600 ft. ... We have found great difficulty in getting sufficient initial velocity to get real starts. While the new machine lifts at a speed of about 23 miles, it is only after the speed reaches 27 or 28 miles that the resistance falls below the thrust. We have found it practically impossible to reach a higher speed than about 24 miles on a track of available length, and as the winds are mostly very light, and full of lulls in which the speed falls to almost nothing, we often find the relative velocity below the limit and are unable to proceed. ... It is evident that we will have to build a starting device that will render us independent of wind.&lt;/em&gt;&quot;&#xA;Source: Page 52 of Octave Chanute Papers: Special Correspondence--Wright Brothers, 1904 | Library of Congress&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Letter 2&lt;/strong&gt;:&#xA;Fragment from the letter written by Wilbur Wright to Octave Chanute on August 28, 1904: &#xA;&quot;&lt;em&gt;Dayton, Ohio, August 28, 1904. Dear Mr Chanute ... ... Since the first of August we have made twenty five starts with the #2 Flyer. The longest flights were 1432 ft., 1304 ft, 1296, ft. and 1260 ft. These are about as long as we can readily make on over present grounds without circling. &lt;strong&gt;We find that the greatest speed over the ground is attained in the flights against the stronger breezes&lt;/strong&gt;. We find that our speed at startup is about 29 or 30 ft per second, the last 60 ft of track being covered in from 2 to 2 1/4 seconds. The acceleration toward the end being very little. When the wind averages much below 10 ft per second it is very difficult to maintain flight, because the variations of the wind are such as to reduce the relative speed so low at times that the resistance becomes greater than the thrust of the screws. Under such circumstances the best of management will not insure a long flight, and at the best the speed accelerates very slowly. In one flight of 39 1/4 seconds the average speed over the ground was only 33 ft per second, a velocity only about 3 ft per second greater than that at startup. The wind averaged 12 ft per second. In a flight against a wind averaging 17 ft per second, the average speed over the ground was 42 ft per second, an average relative velocity of 59 ft per second and an indicated maximum velocity of 70 ft per second. We think the machine when in full flight will maintain an average relative speed of at least 45 miles an hour. This is rather more than we care for at present. Our starting apparatus is approaching completion and then we will be ready to start in calms and practice circling. Yours truly Wilbur Wright.&lt;/em&gt;&quot;&#xA;Source: Page 55 of Octave Chanute Papers: Special Correspondence--Wright Brothers, 1904 | Library of Congress&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-08-29T23:08:55.533" LastActivityDate="2015-09-02T20:12:36.540" Title="The stronger the headwind the faster the plane flies if it is in the reverse command regime?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="19480" PostTypeId="2" ParentId="15734" CreationDate="2015-08-29T23:33:23.167" Score="3" Body="&lt;p&gt;I little off base, but when I flew air ambulances in Southern Louisiana, where helicopter traffic is extremely heavy because of oil field and offshore use, I used the personal call sign &quot;Savior 6&quot; as a personal moniker. I was an RN and Paramedic. Helicopter call signs were known to be Aircare and Acadian Ambulance's AIRMED. &lt;/p&gt;&#xA;" OwnerUserId="10020" LastActivityDate="2015-08-29T23:33:23.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19482" PostTypeId="2" ParentId="15954" CreationDate="2015-08-30T03:52:55.113" Score="3" Body="&lt;p&gt;First, &quot;adverse yaw&quot; refers to the increased drag of a down aileron (and reduced drag on an up aileron) -- which mean that as you deflect the ailerons to roll left (in order to turn left), the adverse yaw makes the nose yaw right -- exactly the opposite of what you want. Therefore you balance any application of aileron with just the right amount of rudder to counteract the adverse yaw. This is called &quot;coordination&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For any control surface (like rudder or aileron) there is a small &quot;dead zone&quot; around neutral, where movement of the surface does not have an appreciable aerodynamic effect. Those narrow strips reduce the size of that dead zone and improve control. Therefore they help, not hurt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you're talking about is what the FAA (and others) call &quot;left-turning tendency&quot;. When flying straight and level, the engine power affects the amount of rudder required, and significantly so. At high power more right rudder is required, and especially so at low speeds like climbing. At low power settings less right rudder is required, especially at high speeds -- so in a descent many aircraft require &lt;em&gt;left&lt;/em&gt; ruder to straight. (Of course this is most applicable to single-engine airplanes where the fin is in the propwash.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To help the pilot with the forces required, surfaces have trim tabs -- see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2025/why-pitch-trim-up-down-roll-left-right-switches-on-yoke-or-control-stick&quot;&gt;Why Pitch Trim Up/Down &amp;amp; Roll Left/Right switches on yoke or control stick?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Incidentally, many older small English engines like the dh Gipsy engine, &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Gipsy_Major&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://en.wikipedia.org/wiki/De_Havilland_Gipsy_Major&lt;/a&gt;, turn the opposite direction so airplanes like the Tiger Moth that use that engine have a right-turning tendency and require left rudder.)&lt;/p&gt;&#xA;" OwnerUserId="9826" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-08-30T03:52:55.113" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19485" PostTypeId="1" AcceptedAnswerId="19487" CreationDate="2015-08-30T07:54:18.433" Score="4" ViewCount="2271" Body="&lt;p&gt;There are a lot of links which give the shape of the airfoil for any given set of camber thickness, position and max. thickness values, but I would like to know if it is possible to get the Lift vs. Angle of attack graph, i.e., in turn lift curve slope, and also Cl/Cd values for every NACA airfoil specified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, I needed the values to begin the designing of a basic propeller blade for my project.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have tried searching a lot. It would be really helpful if anyone could help me proceed.&lt;/p&gt;&#xA;" OwnerUserId="3029" LastActivityDate="2016-09-03T11:49:56.127" Title="Is it possible to get a list of Cl/Cd values for various NACA Airfoils?" Tags="&lt;propeller&gt;&lt;blade&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19486" PostTypeId="1" CreationDate="2015-08-30T09:49:28.123" Score="9" ViewCount="1759" Body="&lt;p&gt;High altitude atmosphere has lower oxygen level. How do aircraft, especially the military ones, prevent engine flameout?&lt;/p&gt;&#xA;" OwnerUserId="10024" LastEditorUserId="1696" LastEditDate="2015-08-31T15:36:47.407" LastActivityDate="2015-08-31T15:36:47.407" Title="What keeps an aircraft engine from flaming out at high altitude?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;&lt;high-altitude&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19487" PostTypeId="2" ParentId="19485" CreationDate="2015-08-30T11:36:10.023" Score="5" Body="&lt;p&gt;Perhaps the most important resource for airfoil data is the NACA (the predecessor of NASA) Report No.824 &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19930090976&quot;&gt;&lt;em&gt;Summary of Airfoil Data&lt;/em&gt;&lt;/a&gt; by Abbott, Von Doenhoff and Stivers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This report contains the description, generation and experimental data like variation of lift, drag and moment coefficients with angles of attack for a number of NACA airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see NACA report No. 460 &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19930091108&amp;amp;hterms=460&amp;amp;qs=Ntx%3Dmode%2520matchallpartial%26Ntk%3DAll%26N%3D4293947576%26Ntt%3D460&quot;&gt;&lt;em&gt;The Characteristics of 78 Related Airfoil Sections from the Tests in the Variable Density Wind Tunnel&lt;/em&gt;&lt;/a&gt; by Jacobs, Ward and Pinkerton.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19930090937&amp;amp;qs=Nm%3D4293947576|Author|Jacobs%2C%2520Eastman%2520N||4293947575|Author|Pinkerton%2C%2520Robert%2520M||4293947504|Author|Ward%2C%2520Kenneth%2520E||4294957998|Subject%2520Terms|AIRFOILS%26N%3D0&quot;&gt;&lt;em&gt;Aerodynamic characteristics of a large number of airfoils tested in the variable-density wind tunnel&lt;/em&gt;&lt;/a&gt; by     Pinkerton and Greenberg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are similar to the first report, but older.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-30T11:36:10.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19488" PostTypeId="2" ParentId="19486" CreationDate="2015-08-30T12:49:47.797" Score="9" Body="&lt;p&gt;The oxygen level at high altitude is the same as at sea level, namely &lt;a href=&quot;https://en.wikipedia.org/wiki/Atmosphere_of_Earth&quot; rel=&quot;nofollow&quot;&gt;20.95%&lt;/a&gt;. What is lower is the oxygen pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To avoid flameout, pilots must avoid to throttle the engine down too much, so a minimum pressure in the combustors can be maintained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designers can increase the altitude performance by building longer combustors. The speed of ignition is pressure dependent, and with lower pressure it takes longer for the fuel-air-mixture to ignite. More length allows more mixing and leaves the mixture more time to react. Also, they can add flame holders which leave pockets of burning fuel close to the injection nozzles, so the mixture is heated more rapidly and ignites more reliably. Normally, flame holders create drag and are reduced to the minimum necessary.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-08-31T06:24:18.350" LastActivityDate="2015-08-31T06:24:18.350" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19489" PostTypeId="2" ParentId="19486" CreationDate="2015-08-30T13:19:05.113" Score="7" Body="&lt;p&gt;At high altitude, aircraft engines have a number of built in safeguards to prevent flameout, like,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The engine igniter is on continuously. This continuous ignition is set automatically by the FADEC if flameout conditions are detected.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case flameout occurs, the FADEC tries to restart the engine automatically (in response to loss of thrust, for example).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The engines also have compressor bleed valves, which serve to prevent compressor stall in case a sudden increase in thrust is demanded from the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Also, as Peter says, at high altitude, the percentage of oxygen remains the same, but the partial pressure is less.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-30T13:19:05.113" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19490" PostTypeId="1" AcceptedAnswerId="19499" CreationDate="2015-08-30T17:30:15.280" Score="2" ViewCount="1062" Body="&lt;p&gt;Under the FAA jurisdiction flight school operations can be conducted under the provisions of part 61 or part 141. If a flight instructor wanted to become a chief instructor at a part 141 flight school, what would they need to be qualified?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-08-30T23:31:16.953" Title="What qualifications are required to become chief instructor at a 141 flight school (FAA)?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;cfi&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19492" PostTypeId="1" CreationDate="2015-08-30T21:11:42.047" Score="1" ViewCount="143" Body="&lt;p&gt;I feel guilty when I chuckle at &lt;a href=&quot;http://www.independent.co.uk/travel/news-and-advice/flight-from-britain-to-turkey-delayed-by-7-hours-after-champagne-cork-damages-ceiling-10478135.html&quot; rel=&quot;nofollow&quot;&gt;this incident.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know what system(s) might be contained in the cabin ceiling which when struck by a high speed champagne cork could lead to deployment of the passenger oxygen masks?&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-08-30T22:53:42.713" Title="What systems, in the cabin ceiling, when damaged could cause the masks to deploy?" Tags="&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19493" PostTypeId="1" CreationDate="2015-08-30T21:29:30.360" Score="2" ViewCount="2285" Body="&lt;p&gt;Other questions on this site say that go-arounds are roughly 1-3 per 1,000 landings. But in many of them, as described by passengers, the wheels don't actually touch the ground. Recently I had a touch-and-go (at Nuka Hiva, a small airstrip on a cliffy island in the Pacific) where our wheels most definitely touched the ground but we immediately accelerated and went around. The brief announcement said it was due to wind shear - we were safely on the ground on the second try so all's well that ends well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious as to whether a true touch-and-go when a pilot is not practicing touch-and-go, on a commercial flight, is a significant rarity. By coincidence, this very same flight started with my first ever aborted takeoff, because a fuel overfill on one side had left us unbalanced; we returned to the gate and span one prop for 10-15 minutes then took off without incident. Am I in lottery-ticket territory?&lt;/p&gt;&#xA;" OwnerUserId="3827" LastActivityDate="2015-08-31T20:51:13.843" Title="How frequent are touch-and-gos?" Tags="&lt;go-around&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19496" PostTypeId="2" ParentId="19492" CreationDate="2015-08-30T22:53:42.713" Score="2" Body="&lt;p&gt;The scenario where ALL the masks drop, which the article somewhat implies but doesn't outright say, sounds fanciful to me.  A cork striking an individual mask unit might cause that individual unit to drop its masks (so if the unit was for one side of a 3/3 seating arrangement, the 4 masks it contains would all drop), but the masks in Boeing airplanes at least are electrically activated, so physical damage to the cabin ceiling seems unlikely to cause a mass deployment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if the cork happened to hit the switch in the COCKPIT, then perhaps all the masks could deploy then.  Normally the masks drop only when the system senses a cabin altitude in the range of 15,000' MSL, but there is a switch the pilot can use to drop the masks if you get the rapid depressurization up high and the automatic system failed.  Typically this switch is safety wired shut for obvious reasons, but if some operator didn't use safety wire and the cork hit the switch JUST RIGHT, then this scenario might work.  (We're talking a one-in-a-million shot here, but it might be possible.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are stories of hard landing sometimes dropping one or a few rows of masks -- this happens when the latch on the container isn't quite as secure as it is supposed to be, and as long as nobody reaches up &amp;amp; activates the flow of O2, it's a pretty simple maintenance procedure to repack and restow the masks.  (If somebody DOES pull down &amp;amp; activate the O2, then the oxygen generator canister for that unit has to be replaced, and that's a more lengthy process -- especially if the generator isn't on hand at that airport!)  So a physical shock from a flying champagne cork being enough to drop the masks from ONE unit isn't too far fetched, but unless you're talking about a really old design where the signal to all units went out mechanically instead of electrically, I have a hard time believing this scenario. (Please note, I'm not claiming that even in the oldest designs a mechanical linkage connecting all the units would necessarily be present -- just that modern designs are NOT mechanical until you get to the latch on an individual unit.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And noting that the plane isn't allowed to fly with masks hanging sounds right... but 7 hours just for repacking one unit seems rather lengthy.  I'd suspect that the paper took the facts of ONE unit deploying, and artfully crafted it to sound like lots or all of the masks dropped.  Sensational writing?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-08-30T22:53:42.713" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19497" PostTypeId="1" CreationDate="2015-08-30T23:21:51.220" Score="3" ViewCount="2996" Body="&lt;p&gt;When parking two airplanes in the hangar, what is minimum safe distance between them?&lt;/p&gt;&#xA;" OwnerUserId="10030" LastEditorUserId="1696" LastEditDate="2017-08-14T15:41:12.527" LastActivityDate="2017-08-14T15:41:12.527" Title="What is the minimum distance between two civil airplanes parked in a hangar?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-storing&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19498" PostTypeId="2" ParentId="19434" CreationDate="2015-08-30T23:23:22.280" Score="3" Body="&lt;p&gt;There are similar vertical profile displays available on Boeing 787, Airbus A380 and Airbus A350 aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an image of the 787's flight deck showing the VSD on the copilot's side:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wYsIQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wYsIQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://www.airliners.net/photo/Boeing/Boeing-787-8-Dreamliner/2112928&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10025" LastEditorUserId="14897" LastEditDate="2019-04-11T16:38:32.757" LastActivityDate="2019-04-11T16:38:32.757" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="19499" PostTypeId="2" ParentId="19490" CreationDate="2015-08-30T23:31:16.953" Score="2" Body="&lt;p&gt;The requirements are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=193036e5e57cba2af1a052c85a8415dd&amp;amp;mc=true&amp;amp;node=pt14.3.141&amp;amp;rgn=div5#se14.3.141_135&quot; rel=&quot;nofollow&quot;&gt;14 CFR 141.35&lt;/a&gt;, &lt;em&gt;Chief instructor qualifications&lt;/em&gt;. They're too long to quote here in full and the exact requirements depend on the type of instruction, but in summary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hold a commercial or ATP certificate&lt;/li&gt;&#xA;&lt;li&gt;Hold a CFI certificate&lt;/li&gt;&#xA;&lt;li&gt;Pass knowledge and proficiency tests&lt;/li&gt;&#xA;&lt;li&gt;Meet minimum flight time requirements (depending on the type of instruction, e.g. 1000 hrs PIC time is required for private pilot instruction)&lt;/li&gt;&#xA;&lt;li&gt;Meet minimum flight training time requirements&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For training pilots for an instrument rating, the chief instructor also needs an instrument rating, instrument flight time and instrument training experience.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-08-30T23:31:16.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19500" PostTypeId="1" AcceptedAnswerId="19502" CreationDate="2015-08-30T23:34:47.667" Score="9" ViewCount="20473" Body="&lt;p&gt;The FAA regulates logging time in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=40760189a03dfea0b501608f33820a45&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 61.51&lt;/a&gt;. There are &lt;a href=&quot;https://aviation.stackexchange.com/search?q=PIC%20Time%20is%3Aquestion&quot;&gt;plenty of questions&lt;/a&gt; about logging PIC time, as well as &lt;a href=&quot;https://aviation.stackexchange.com/q/8969/136&quot;&gt;SIC time&lt;/a&gt;. Another type remains: what can be logged as total time? It's only mentioned once:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Total flight time or lesson time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is clear that any time logged as dual, PIC, or SIC can be logged as total time. Is total time merely the sum of those, minus any overlap, or is there a situation where total time can be logged but none of the others?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, two situations arise:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;I'm at the controls of an aircraft I'm not rated for (i.e. an ASEL pilot in the right seat of a multi-engine aircraft, where the other pilot is appropriately rated and not a CFI). I can't log PIC, SIC, or dual - but can I log total time?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In a plane I'm rated for, I pass the controls to a non-certificated passenger. I'm not a CFI. I cannot log PIC, SIC, or dual while my passenger is the sole manipulator of the controls, but I am acting as the PIC for this portion of the flight. Can I log this as total time?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2021-04-09T20:43:22.273" Title="What can be logged as Total Time?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;&lt;far-61&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19501" PostTypeId="2" ParentId="19500" CreationDate="2015-08-31T00:13:44.573" Score="-2" Body="&lt;p&gt;The interpretation of &quot;Total Time&quot; I've always seen is the sum of all the other categories. That is, your &quot;total time&quot; should be the sum of your PIC/SIC/Instruction (not as PIC/SIC) time. That said, it's your logbook, you can log whatever you want as &quot;total time&quot; (e.g. if your airline co-pilot has the fish &amp;amp; you get called up to sit right seat you can log that as &quot;total time&quot; if you wish - just not as one of the categories that &quot;counts&quot; under the regs: PIC/SIC/Instruction Received etc.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that your second example is a different situation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In a plane I'm rated for, I pass the controls to a non-certificated passenger. I'm not a CFI. I cannot log PIC, SIC, or dual while my passenger is the sole manipulator of the controls, but I am acting as the PIC for this portion of the flight. Can I log this as total time?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You &lt;strong&gt;are&lt;/strong&gt; acting as PIC in this situation. Who is manipulating the controls is irrelevant: As your passenger is not rated to act as PIC of airplane carrying passengers you must be filling that role. You would therefore log PIC time in this case (you &lt;em&gt;cannot&lt;/em&gt; however log it as &quot;dual given&quot;, nor can your passenger log it as &quot;dual received&quot;, because you are not a CFI).&lt;br&gt;&#xA;This is also true if your passenger holds a student pilot certificate, or a certificate for a different category/class of aircraft (e.g. if they have a rotorcraft certificate they still can't be PIC of an airplane - they are not rated for that category of aircraft).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-31T00:13:44.573" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19502" PostTypeId="2" ParentId="19500" CreationDate="2015-08-31T00:34:47.987" Score="5" Body="&lt;p&gt;&quot;Total time&quot; isn't an officially defined term as far as I know. Most people seem to use it to mean &quot;total flight time&quot;, i.e. the total of their PIC, SIC and flight training time (excluding simulator training).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, you can log and count whatever you want in your logbook provided that you log at least the items required in &lt;a href=&quot;https://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.51(a)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;em&gt;Training time and aeronautical experience&lt;/em&gt;. Each person must&#xA;  document and record the following time in a manner acceptable to the&#xA;  Administrator:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Training and aeronautical experience used to meet the requirements&#xA;  for a certificate, rating, or flight review of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The aeronautical experience required for meeting the recent flight&#xA;  experience requirements of this part.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, the bottom line is that &quot;total time&quot; is whatever you want it to be, and if you want to log 'fun time' in aircraft that you aren't qualified to fly then go ahead; the time just won't count for anything as far as the FAA is concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your two scenarios:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You can't log any 'FAA time' because you're not certified to fly the&#xA;aircraft as PIC or SIC, and you aren't receiving training. You might note it in your logbook for your own reasons but you can't count it towards anything for the FAA's purposes.&lt;/li&gt;&#xA;&lt;li&gt;You can't log 'FAA time' here either, for the reasons you mentioned. You're acting PIC for the entire flight, of course, but &lt;em&gt;acting&lt;/em&gt; as PIC doesn't automatically let you &lt;em&gt;log&lt;/em&gt; PIC unless other conditions are met. 61.51(e) lists all the ways you can log PIC time, e.g. sole manipulator, acting as PIC when more than one crewmember is required.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-11-05T01:40:35.057" LastActivityDate="2018-11-05T01:40:35.057" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="19503" PostTypeId="1" CreationDate="2015-08-31T00:39:28.887" Score="8" ViewCount="836" Body="&lt;p&gt;My friend landed at &lt;a href=&quot;https://en.wikipedia.org/wiki/Richard_Pearse_Airport&quot;&gt;Timaru Airport&lt;/a&gt; and when he put the aircraft into the hangar the altimeter reading was approximately 100ft [airport elevation is 89ft]. When he got back to go flying two weeks later the altimeter reading was over 4000ft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He replaced the altimeter with a new one and now the same thing has happened again. Has anybody got any idea about what has happened?&lt;/p&gt;&#xA;" OwnerUserId="10032" LastEditorUserId="62" LastEditDate="2015-08-31T00:43:46.780" LastActivityDate="2015-09-07T01:41:07.897" Title="Why might an altimeter read incorrectly by 4000ft after sitting on the ground for some time?" Tags="&lt;aircraft-systems&gt;&lt;altimeter&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19505" PostTypeId="1" AcceptedAnswerId="19508" CreationDate="2015-08-31T07:38:56.443" Score="4" ViewCount="689" Body="&lt;p&gt;Following on from &lt;a href=&quot;https://aviation.stackexchange.com/questions/12458/why-are-first-business-class-seats-at-the-front-of-aircraft-where-it-is-the-leas&quot;&gt;Why are first/business class seats at the front?&lt;/a&gt;, in which part of a large commercial jet cabin would I experience the least turbulence? On the one hand I would have said that sitting near the wings (near the centre of gravity) is best, but subjectively it feels like the ride near the front is &quot;smoother&quot;. Can anyone give me some more solid information? I imagine it also depends on the aircraft type?&lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-02T06:26:23.720" Title="Where should I sit to experience the least turbulence?" Tags="&lt;turbulence&gt;&lt;seats&gt;&lt;comfort&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19506" PostTypeId="2" ParentId="19497" CreationDate="2015-08-31T07:50:45.533" Score="7" Body="&lt;p&gt;If you look at some civil-aircraft hangars, you will see that the planes are almost touching each other, as you can see here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Lzrim.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lzrim.jpg&quot; alt=&quot;Civil aircraft hangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The planes are so close to each other to fit a maximum amount of planes into a hangar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are different types of hangars. Some are built just to store aircraft when they aren't used, some are built for aircraft-maintenance-operations and can even contain robots. Hangars can be simple buildings with a big and open space or they can be very complex facilities. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want more infos about aircraft hangars take a look &lt;a href=&quot;https://www.wbdg.org/design/aviation_hangar.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find the minimum separation distances between aircraft and minimum distances between the aircraft and other obstructions &lt;a href=&quot;https://www.wbdg.org/ccb/browse_doc.php?d=3591&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at this table from &lt;a href=&quot;http://wbdg.org/ccb/AF/AFH/ARCHIVES/32_1084.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; document (page 30):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/orbfA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/orbfA.png&quot; alt=&quot;Minimum safe distance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the minimum distance between the wings from two parked aircraft is not always the same.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dimensions vary for different models and configurations of aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you want to find out the min. distance of an A380, you need to take a look at the documents provided by Airbus. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;, there is no basic rule. The safe distance is determined by the aircraft-type, configuration and the hangar (owner).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airliners are stored in the hangar, they can be pretty close to each other. However, maintenance of a big airliners takes up a lot of space:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b2c2h.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b2c2h.jpg&quot; alt=&quot;A380 Maintenance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="7532" LastEditDate="2017-08-14T15:36:36.400" LastActivityDate="2017-08-14T15:36:36.400" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="19507" PostTypeId="2" ParentId="19505" CreationDate="2015-08-31T08:45:04.763" Score="2" Body="&lt;p&gt;The seats over the wings should have the least turbulence as they are near to the center of mass and center of pressure(over which the lift acts).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The front and rear should experience more (with slightly more in the aft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thought I'm not able to find any scientific studies into this, see &lt;a href=&quot;http://www.usatoday.com/story/travel/flights/2014/07/10/5-myths-about-air-turbulence/12301043/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://getawaytips.azcentral.com/place-sit-airplane-less-turbulence-3999.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-08-31T08:45:04.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19508" PostTypeId="2" ParentId="19505" CreationDate="2015-08-31T09:07:14.767" Score="9" Body="&lt;p&gt;The elasticity of the fuselage does indeed dampen the load factors from gusts somewhat. Therefore, gust-induced accelerations are a little higher over the wing than in the forward or rear fuselage. If the gust causes a pitching motion, this creates its own accelerations which adds to the bumps from the vertical accelerations. Elevator deflections cause similar pitching motions, and their accelerations are more pronounced in the rear fuselage since the aircraft will pivot around a point ahead of the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main factor, however, is the location of the axis of rotation of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8488/why-is-the-dutch-roll-called-so&quot;&gt;Dutch roll eigenmotion&lt;/a&gt; of airliners. This is a weakly damped oscillation which creates lateral accelerations which are bigger the more aft you sit in the fuselage. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_880&quot; rel=&quot;nofollow noreferrer&quot;&gt;Convair 880&lt;/a&gt; was hurriedly test-flown with nobody sitting in the back, and the pilots were happy with its comfort level. The first passengers, however, got seasick from the Dutch roll motion, which was only detected when the passengers sitting in the rear of the cabin complained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern airliners offer better comfort thanks to artificially enhanced stability, but even there you are better off sitting in front. I once flew on an &lt;a href=&quot;https://en.wikipedia.org/wiki/EgyptAir&quot; rel=&quot;nofollow noreferrer&quot;&gt;Egypt Air&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 777&lt;/a&gt; from Cairo to Frankfurt, and the captain flew through the tops of &lt;a href=&quot;https://aviation.stackexchange.com/questions/16700/why-is-the-cumulonimbus-cloud-formation-so-dangerous&quot;&gt;Cumulus clouds&lt;/a&gt; sitting over the Alps. Soon the obvious sounds and smell told me that people in the back were filling their air sickness bags. Maybe half of the rear third of the seats was affected, while the forward two thirds had only a few cases of airsick passengers. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-02T06:26:23.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19509" PostTypeId="1" AcceptedAnswerId="19512" CreationDate="2015-08-31T10:04:03.390" Score="6" ViewCount="2742" Body="&lt;p&gt;Why are ARINC labels reversed before transmitting them to destination and the LSB (less significant bit) is transmitted first:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Actual label = 0x58: &lt;code&gt;0101 1000&lt;/code&gt;&lt;/li&gt;&#xA;&lt;li&gt;Transmitted as label = 0x1A: &lt;code&gt;0001 1010&lt;/code&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is there any particular advantage over formal transmission and label reversed transmission?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also all systems are designed for odd parity. Why is that?&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="3201" LastEditDate="2015-08-31T13:14:05.383" LastActivityDate="2021-02-03T14:35:49.120" Title="Why are ARINC labels are transmitted LSB first?" Tags="&lt;aircraft-design&gt;&lt;software&gt;&lt;aircraft-subsystem&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19512" PostTypeId="2" ParentId="19509" CreationDate="2015-08-31T13:23:55.970" Score="10" Body="&lt;p&gt;&lt;strong&gt;Revised answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ARINC 429 frame is composed of 4 bytes (32 bits numbered by convention 1 to 32 from right to left). Bits 11 to 29, which are the payload of the frame, can represent data using different formats, e.g. binary or BCD data. The label is used to indicate the content of the data field, and which format is used, and is necessary to convert data bits into useful information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kr6Cm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kr6Cm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;ARINC 429 frame used in BCD format (&lt;a href=&quot;http://leonardodaga.insyde.it/Corsi/AD/Documenti/ARINCTutorial.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The label is usually spelled as an octal quantity (rather than decimal or hexadecimal), e.g. &lt;code&gt;01010110&lt;/code&gt;&lt;sub&gt;2&lt;/sub&gt; will be spelled as 126&lt;sub&gt;8&lt;/sub&gt; (&lt;code&gt;01 010 110&lt;/code&gt;) rather than 56&lt;sub&gt;16&lt;/sub&gt; (&lt;code&gt;0101 0110&lt;/code&gt;) or 86&lt;sub&gt;10&lt;/sub&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way bits are numbered somehow makes the label the &quot;least significant byte&quot; and bit 1 the &quot;least significant bit&quot;. However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The format above is for naming and ordering information, but doesn't tell how bits are really stored in components memory.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In digital engineering, bits are usually numbered from 0 to 31, as the number actually indicates the weight of the bit: 0 is 2&lt;sup&gt;0&lt;/sup&gt; (1), 4 is 2&lt;sup&gt;4&lt;/sup&gt; (16). In this convention bit 0 is indeed less significant than bit 31.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The ARINC 429 data bus is composed of 2 wires and the ground reference. When an ARINC frame is transmitted on the bus, it must be serialized, which means sending bits one at a time. The transmission order is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The label byte transmitted first, &quot;MSB&quot; first: 8-7-6-5-4-3-2-1.&lt;/li&gt;&#xA;&lt;li&gt;The other bits are then transmitted &quot;LSB&quot; first: 9-10-11 ... 30-31-32.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, back to your question, why not using the left to right order for the whole frame? Or at least the left to right order for the label if it's sent first?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Like &lt;a href=&quot;https://en.wikipedia.org/wiki/CAN_bus&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAN Protocol&lt;/a&gt; Identifier Fields, ARINC 429 label fields are&#xA;  transmitted most significant bit first. [...] This notional reversal&#xA;  also reflects historical implementation details.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So let's assume there is no reason to reverse the label bits, other than historical implementations that wanted to mimic the behavior of CAN. In the French version of this Wikipedia article, it is stated that this reversal helped to read the label when looking at a frame using an oscilloscope. The MSB arriving first also appears on the left of the display (the signal on an oscilloscope generally enters on the right of the screen and scroll towards the left side as a function of the time):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VdOtM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VdOtM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;ARINC 429 bit stream on a datascope (&lt;a href=&quot;https://fr.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a bit baffled by this explanation, as engineers working with binary representations are used to read them is both directions quite easily after a short time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still according to Wikipedia, hardware used to serialize and de-serialize the ARINC word were actually insensitive to the order of the label bits:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ARINC 429 transceivers have been implemented with 32-bit shift&#xA;  registers. Parallel access to that shift register is often&#xA;  octet-oriented. As such, the bit order of the octet access is the bit&#xA;  order of the accessing device, which is usually LSB 0; and serial&#xA;  transmission is arranged such that the least significant bit of each&#xA;  octet is transmitted first. So, in common practice, the accessing&#xA;  device wrote or  read a &quot;reversed label&quot; (for example, to transmit a&#xA;  Label 2138 [or 8B16] the bit-reversed value D116 is written to the&#xA;  Label octet). Newer or &quot;enhanced&quot; transceivers may be configured to&#xA;  reverse the Label field bit order &quot;in hardware.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;About odd parity&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is usual in digital serial communication to use data value changes (0 to 1 or 1 to 0) to derive a clocking clue in order to ensure the receiver samples the line voltage at the right time. This is less expensive than transmitting the clock signal on a separate wire. As each bit lasts the same time, the receiver uses a local clock that is roughly in sync with the transmitting clock. To actually maintain the synchronization in the long term, the receiver uses the raising and falling edges of the signal to detect bit borders and phase-align its clock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rgJm8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rgJm8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Resynchronization of receiver clock on front and rear edges of the signal&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That works well if the delay between edges is short. This means avoiding sending long series of 0 or 1. The parity bit can help. For data containing only 0 bits (or 1 bits) the odd parity bit will be 1 (or 0), preventing long edgeless streams to occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some uses of ARINC 429, the parity bit is not transmitted, and is used for data, but nevertheless it seems superfluous for sync in this case since the link protocol is 3-level with return to zero, ensuring two edges for each bit of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0cTAs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0cTAs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Return to zero coding (&lt;a href=&quot;https://electronics.stackexchange.com/questions/181715/different-wave-form-of-rs485&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:33:10.950" LastActivityDate="2016-03-31T15:07:25.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19513" PostTypeId="1" CreationDate="2015-08-31T13:35:41.887" Score="19" ViewCount="3080" Body="&lt;p&gt;Why do the civil aviation authorities of Turkey (&lt;a href=&quot;http://www.mondaq.com/turkey/x/277124/Aviation/Lmtaton+On+Arcraft+Ages+In+Turksh+Avaton+Industry&quot;&gt;15 years civil, 25 years cargo&lt;/a&gt;) and United Arab Emirates (20 years) limit the age of aircraft flying over their territory? I think if an old plane receives good maintenance and doesn't have too many cycles, it's still a safe plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, see this news article of a leased Kabo 747-200 that is being refused clearance by the UAE because it is older than 20 years.(&lt;a href=&quot;http://www.aerotelegraph.com/boeing-b747-747-leasing-biman-bangladesh-kabo-air-nicht-erlaubt-saudi-arabien-alter&quot;&gt;German&lt;/a&gt;/&lt;a href=&quot;http://bdnews24.com/bangladesh/2013/09/07/aircraft-too-old-for-saudi-clearance&quot;&gt;English&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3734" LastEditorUserId="1696" LastEditDate="2015-08-31T22:23:51.430" LastActivityDate="2015-09-01T03:53:54.990" Title="Why do Turkey and UAE limit the age of aircraft flying over their territory?" Tags="&lt;regulations&gt;&lt;airworthiness&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19514" PostTypeId="1" CreationDate="2015-08-31T13:45:50.687" Score="3" ViewCount="12139" Body="&lt;p&gt;Often when approaching landing, I feel the aircraft slow down considerably, it hasn't landed yet, but kind of hovers around waiting for clearance to land. Thus I was wondering, is there any defined minimum cruise speed for airliners.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2018-04-15T04:54:42.617" Title="What's the minimum cruise speed of modern airliners?" Tags="&lt;airspeed&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19515" PostTypeId="2" ParentId="19493" CreationDate="2015-08-31T13:53:34.153" Score="1" Body="&lt;p&gt;In larger aircraft you may not be able to execute a go around once you have touched down but its not always because of weather. This mainly has to do with the fact that once a plane touches down (situation depending) it may have already committed to the landing and will no longer be able to get airborne with the remaining runway. There is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/15335/when-a-large-commercial-jet-touches-down-is-it-committed-to-stopping&quot;&gt;discussion here&lt;/a&gt; on the topic and an &lt;a href=&quot;http://www.propilotmag.com/archives/2008/Dec08/A4_Pilot_techniques_p1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;article here&lt;/a&gt; that covers it as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It generally takes more distance to take off than land and a considerable amount of speed is bleed off during the flair and subsequent touch down. If a plane touches down at the proper touch down point on a runway it may not have enough distance to accelerate and become airborne again by the other end of the runway. Further more you can complicate the situation with things like thrust reversers which, once deployed force you to commit to the landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airport in question has a 5578 x 98 feet runway which is a solid size but chances are you were flying a plane on the smaller side. Generally the smaller the plane the less runway you need to land and take off so go arounds after touchdown are possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To directly answer your question, in some instances they do happen but they will be recorded as an aborted landing. In other cases (heavy crosswinds) you may have only one side of the mains touch (does that count as a touch down?). The runway length and aircraft size/performance are the main factors and there are so many combinations of that.      &lt;/p&gt;&#xA;&#xA;&lt;p&gt;--Edit-- &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you have provided the make and model of the plane we can extrapolate a bit more. You can find the &lt;a href=&quot;http://www.atraircraft.com/products_app/media/pdf/Fiche_72-600_Juin-2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;full specs here&lt;/a&gt; but lets take the the At TOW for 300 Nm - Max pax - 3,000 ft - ISA +10 - situation which is quoted at 4,626 ft. Take off speed at max load is 116 Kts (and you were landing so you were on the lower end of the fuel which means you were below max load even with full passengers). Likewise approach speed is 113 Kts. Some of this depends on the pilots precision but It should be (and obviously was) possible to touch down, full power, and get airborne again in enough distance on the strip. Sine you would only need to make up 3 Kts assuming he came in on the mark at 113. They would lose speed in the touch down but if they were on the throttles fast enough it would work.     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-08-31T20:51:13.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19516" PostTypeId="2" ParentId="19513" CreationDate="2015-08-31T14:00:20.050" Score="24" Body="&lt;p&gt;Sounds like a market protectionist move by the nations. i.e. The airlines of UAE and Turkey are relatively new. At least their current expansion to a scale that is competitive with the major international airlines is relatively recent. Their airports have also undergone fairly recent expansions to capitalize on their geographical location as hubs between N. America / EU to Asia-Pacific nations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose they give their own airlines a competitive advantage by restricting older aircraft. The US / European carriers can only allocate the fraction of their fleet that is new to flights to Turkey / UAE which constrains their activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The average fleet age of some airlines in 2013:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Delta  16 years&lt;/li&gt;&#xA;&lt;li&gt;United  13 years&lt;/li&gt;&#xA;&lt;li&gt;American + US 13 years&lt;/li&gt;&#xA;&lt;li&gt;Lufthansa 13 years&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now compare with&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Turkish  8 years&lt;/li&gt;&#xA;&lt;li&gt;Emirates 6 years&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Basically, international trade treaties have made it difficult for nations to overtly engage in protectionist measures. So bureaucrats figure out indirect means under the guise of technology, quality etc. that are ostensibly  not favoring domestic industry but are effectively a discriminatory measure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take the numbers with a pinch of salt because airline fleets are continuously upgraded so the average age of a fleet can change pretty rapidly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Caveat:&lt;/strong&gt; The average fleet age may not be representative of the equipment flying international sectors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PS.&lt;/strong&gt; I don't think the regulation has much to do with real safety because safety is concerned with many other factors outside of aircraft age. The safety aspects are better regulated by adopting the FAA safety watch-list based on national assessments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At best, this sounds safety theater. Not safety. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-09-01T03:53:54.990" LastActivityDate="2015-09-01T03:53:54.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19517" PostTypeId="2" ParentId="19514" CreationDate="2015-08-31T14:01:45.490" Score="11" Body="&lt;p&gt;It's called the stall speed. Below which the wings won't give enough lift to stay airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another minimal speed to adhere to is the minimal control speed. Below that the controls surfaces won't be able to counteract suddenly losing an engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However slowing down before landing has nothing to do with waiting on their turn/clearance. If they need to wait they go around in a circle instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The slowing down is so they touch down with as low speed as possible to limit the braking distance needed on the runway.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-08-31T14:01:45.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19518" PostTypeId="2" ParentId="19446" CreationDate="2015-08-31T14:02:10.673" Score="22" Body="&lt;p&gt;It's a mirror for a periscope used by the instructor (sitting in the back seat) to see the runway on landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As reported &lt;a href=&quot;http://forums.eagle.ru/showthread.php?t=30371&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, two-seater versions of MiG-21 and MiG-23 also have the same feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this picture, the periscope is, in fact, clearly visible on the back seat's canopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0o0Lq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0o0Lq.jpg&quot; alt=&quot;Image of MiG, showing mirror over canopy&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image courtesy of &lt;a href=&quot;http://www.airvectors.net/avmig23_2_5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airvectors.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="14897" LastEditDate="2019-02-03T14:04:53.947" LastActivityDate="2019-02-03T14:04:53.947" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19520" PostTypeId="2" ParentId="19514" CreationDate="2015-08-31T14:17:04.687" Score="5" Body="&lt;p&gt;The lift a wing is able to generate is proportional to square of speed¹. If the aircraft is moving through the air too slowly, it will stall², pitch down and start to descend rapidly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a fixed-wing aircraft³ must move at least some speed, called &lt;em&gt;stall speed&lt;/em&gt; or $V_S$. And normally some margin error should be left, so the aircraft never flies slower than about $1.3×V_S$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the $V_S$ is depends on the aircraft and the &lt;em&gt;weight&lt;/em&gt;. Because lift is needed to balance weight, less weight means less lift is needed and thus less air flow to generate it. For jet airliners the stall speeds may range from around 100 knots when light (~185 km/h, ~115 mph) to maybe 130 knots (~240 km/h, ~150 mph) when loaded⁴.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, at altitude below 10,000 ft, &lt;em&gt;maximum&lt;/em&gt; speed of 250 knots (~463 km/h, ~288 mph) is usually defined so the pilots have enough time to see each other when flying near the airports under visual flight rules or in case the controller makes a mistake.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ It is actually proportional to &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamic_pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;dynamic pressure&lt;/a&gt;, which is proportional to pressure and square of speed, so as the aircraft climbs, the minimum speed increases. Modern airliners fly very high (usually 32,000 to 42,000 ft) where the lower pressure and corresponding lower drag allows flying much faster, but the minimum speed is also higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² Lift is proportional to dynamic pressure and angle of attack. At slower speed the wing flies at higher angle of attack, which is how the nose of the aircraft still points up when it is approaching to landing. The wing is able to provide more lift up to &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall&quot;&gt;critical angle of attack&lt;/a&gt; above which it stalls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;³ Rotorcraft (helicopters) create the air flow by rotating their wings instead and therefore don't need any forward speed. In fact they stall when flying too fast instead when the retreating blade is no longer moving aft fast enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;⁴ These are values for &lt;a href=&quot;https://en.wikipedia.org/wiki/High-lift_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;high lift devices (flaps and slats)&lt;/a&gt; deployed. With them retracted, the stall speed is higher. The stall speed also depends on the relative wing area of particular aircraft. For example A318, A319, A320 and A321-200 all have the same wing and therefore the same stall speed at the same weight, but they have different size and therefore different typical weights. There is similar difference between say B737-700, B737-800 and B737-900.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-08-31T14:17:04.687" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19523" PostTypeId="2" ParentId="19513" CreationDate="2015-08-31T15:51:54.930" Score="6" Body="&lt;p&gt;I don't believe there's been a stated reason, but we can surmise several&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newer aircraft have newer, more efficient engines meaning typically lower noise and less pollution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newer aircraft are typically better maintained. Obviously this isn't always true, and some older aircraft can be very well maintained, but it's easier to just put a blanket cut-off policy in place, rather than waste time on a case-by-case basis. It also gives the perception to the public that a safety policy has been put in place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if they aren't better maintained, newer aircraft are less likely to have developed faults. Again, there is no guarantee, but it provides a lower risk profile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as stated in another answer, there is possibly a degree of protectionism - local airlines in that part of the world tend to be fairly young with modern fleets, whereas some of the larger carriers elsewhere have older fleets. I'm not convinced this would be an effective tactic, however, as the likes of Lufthansa, British Airways etc have enough new planes to service routes to the UAE etc&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And finally, older aircraft tend to be snapped up by less.... Conscientious... Airlines. Age limits are a good way to force these types of low-cost, potentially 'iffy' airlines out of contention if you don't want them flying your people in and out of your airlines.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-08-31T17:28:45.903" LastActivityDate="2015-08-31T17:28:45.903" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19524" PostTypeId="1" CreationDate="2015-08-31T17:02:24.450" Score="1" ViewCount="976" Body="&lt;p&gt;As air flows over the top of an aerofoil the pressure drops. Compared to the high / normal pressures on the underside, a pressure gradient is formed with higher pressure further above the wing. You get:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;less pressure = less particles = less density &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sketch summarizes what I know so far:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xFfmL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xFfmL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Does lower air density above the wing mean the air weighs less compared to the weight of the air underneath the wing? If the difference is negligible then it's OK, we can forget it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What forces act on the air particles causing them to speed up?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="10037" LastEditorUserId="10037" LastEditDate="2015-09-02T09:13:26.383" LastActivityDate="2015-09-02T09:13:26.383" Title="What really causes a low-pressure gradient over the top of an aerofoil?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="12" ClosedDate="2015-08-31T17:45:22.833" ContentLicense="CC BY-SA 3.0" />
  <row Id="19525" PostTypeId="2" ParentId="19497" CreationDate="2015-08-31T17:10:06.503" Score="3" Body="&lt;p&gt;&quot;Don't hit the other planes. Don't hit the walls. Don't hit anything else in the hangar.&quot; - that's the minimum safe distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other requirements (e.g. by fire code: the number of aircraft stored in a hangar may be restricted by the amount of fuel each aircraft holds, and by the hangar's fire suppression capabilities).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly in a hangar where active maintenance is happening the space between each aircraft may be larger to allow maintenance personnel access to each aircraft.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-08-31T17:10:06.503" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19528" PostTypeId="2" ParentId="19524" CreationDate="2015-08-31T17:31:18.130" Score="0" Body="&lt;p&gt;This is my understanding: A combination of the shape, angle of attack and movement of the wing creates high pressure on the front side of the wing and low pressure on the back side. By front and back I mean the part that is facing the oncoming air and the part that cannot &quot;see&quot; the oncoming air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The low pressure is there because of this. This is the pressure difference which causes lift. Some lift also comes from the downdraft caused by air moving downwards at the trailing edge of the wing due to the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This article has a video that shows airflow over a wing.&#xA;&lt;a href=&quot;http://www.cam.ac.uk/research/news/how-wings-really-work&quot; rel=&quot;nofollow&quot;&gt;http://www.cam.ac.uk/research/news/how-wings-really-work&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-08-31T17:31:18.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19529" PostTypeId="2" ParentId="19514" CreationDate="2015-08-31T18:07:59.370" Score="4" Body="&lt;p&gt;The minimum speed at which the aircraft can fly (cruise) is called the &lt;em&gt;stall speed&lt;/em&gt;. At this speed, the lift is equal to the aircraft weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift L is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L = \frac{1}{2}C_{L} \rho S V^{2}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_{L}$ is the lift coefficient, $\rho$ is the density at that altitude and $S$ is the wing planform area. During level, unaccelerated flight, the lift is equal to weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L = W = \frac{1}{2}C_{L} \rho S V^{2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This gives the stalling speed as,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V_{s} = \sqrt{\frac{2 W}{\rho C_{L_{max}} S}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the minimum speed at which the aircraft can fly. Note that it depends on three things: the Weight of the aircraft, the density of the air and the $C_{L_{max}}$ of the wing section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During landing, two things happen: the weight is lesser (compared to takeoff weight), and the flaps are deployed, which increases the $C_{L_{max}}$, which in turn reduces the minimum speed required for flight. This is the reason you're feeling a reduction in speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ISQyb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ISQyb.jpg&quot; alt=&quot;Boeing 777 Flaps&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: assets.decodedscience.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yzt5p.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yzt5p.png&quot; alt=&quot;Boeing 747-200 Lift&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: Stall Speed, Prof. Dr. Mustafa Cavcar&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, aircraft are flown well over the stall speed. If the margin (between flight speed and stall speed) is maintained, then your flight speed will reduce when the stall speed is reduced.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-09-01T13:30:50.460" LastActivityDate="2015-09-01T13:30:50.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19530" PostTypeId="1" CreationDate="2015-08-31T20:15:42.207" Score="10" ViewCount="1239" Body="&lt;p&gt;I noticed on an American Airline flight a gap of about 4 inches between the floor of the bridge and the airplane. Wide enough that if the passenger is not paying attention to the floor the foot may slip in between or at  least get stuck.  The flight attendant said there's always a gap. I've seen a gap but not that wide. Is there a maximum acceptable gap? &lt;/p&gt;&#xA;" OwnerUserId="10041" LastEditorUserId="19" LastEditDate="2017-01-09T11:08:24.803" LastActivityDate="2019-01-07T12:15:02.040" Title="What is the maximum acceptable gap between the jet bridge and airplane door?" Tags="&lt;safety&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19531" PostTypeId="1" CreationDate="2015-08-31T21:32:17.947" Score="4" ViewCount="1431" Body="&lt;p&gt;How many volts does the typical airliner CSD (Constant Speed Drive) produce?  I've read the CSD's output is typically 3-phase 115 V&lt;sub&gt;AC&lt;/sub&gt; @ 400 Hz. Is that correct?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also read the typical airliner generator puts out &quot;in-phase 28 V&lt;sub&gt;AC&lt;/sub&gt;&quot;. Is that correct?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the CSD provide more voltage than the generator needs and the generator reduces the voltage via a transformer?&lt;/p&gt;&#xA;" OwnerUserId="10042" LastEditorUserId="-1" LastEditDate="2016-11-11T15:07:55.337" LastActivityDate="2016-11-12T17:59:19.987" Title="What is the typical voltage and frequency of the electrical generator in an airliner?" Tags="&lt;airliner&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19532" PostTypeId="2" ParentId="19478" CreationDate="2015-08-31T21:37:36.507" Score="1" Body="&lt;p&gt;The question is not valid as asked because of a couple of factors. First, an aircraft in flight operates within a given airmass, and is unaffected by the 'wind'. Second, the 'reverse command regime' refers to an angle of attack beyond which (given constant thrust) increasing the angle of attack results in decreased net lift. In other words, the aircraft will begin to descend (or rate of descent will increase) when the stick is pulled back, i.e. the reverse of the 'commanded' climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there were a wind-shear (relatively rapid increase in wind-speed), there would be a temporary increase in aircraft performance (lift and/or airspeed) due to the inherent increase in airspeed, but this will only be sustained for the duration of of the change in wind-speed. This does not appear to be what you are describing, but rapid changes in wind velocity are the only phenomena that would affect aircraft performance. In no case would airspeed be affected by a constant wind, regardless of the velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine an airplane flying at 100mph within an airmass that's moving at 200mph in the opposite direction; that aircraft is traveling backward (relative to the ground) at 100mph. Meanwhile, another aircraft is also flying at 100mph in the opposite direction (with the wind), resulting in a ground speed of 300mph. Both aircraft have the same airspeed; they both 'feel' the same 100mph relative wind. The movement of the airmass within which they operate is not relevant to their performance.&lt;/p&gt;&#xA;" OwnerUserId="10043" LastActivityDate="2015-08-31T21:37:36.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19533" PostTypeId="2" ParentId="19478" CreationDate="2015-08-31T21:42:23.967" Score="4" Body="&lt;h2&gt;How was the Flyer II launched into the air?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The first thing to consider is the take-off method used by the Wrights when flying on &lt;a href=&quot;http://www.thewrightbrothers.org/1904.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Huffman Prarie in 1904&lt;/a&gt;. The plane was set on a wheeled dolly which moved along a single wooden rail, the end of which was slightly elevated to give the aircraft more pitch angle and some vertical speed upon leaving the rail. &lt;a href=&quot;https://aviation.stackexchange.com/questions/11330/how-did-the-wright-plane-takeoff-land&quot;&gt;This answer&lt;/a&gt; has some details on the rails, but centers on the catapult which was added later in 1904.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Drag components&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The next is the general composition of drag in subsonic aircraft. Two main components can be distinguished, one growing with the square of airspeed and caused by friction (called zero-lift drag), and one dropping with the square of airspeed, caused by the downward acceleration of air when lift is created (called &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=4%7C0.0488#8882&quot;&gt;induced drag&lt;/a&gt;). The plot below shows them and the total drag as a green line. The drag minimum is attained at some intermediate speed. As long as the aircraft flies slower than at the speed of minimum drag, speeding up will lower the total drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xUgU3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xUgU3.png&quot; alt=&quot;Plot of the drag components over speed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that I took the liberty of adding some extra drag at the slow end of both drag curves to simulate the additional pressure drag caused by the beginning flow separation at low speed. When looking at wind tunnel data from tests on models of the 1903 Flyer (taken from &lt;a href=&quot;http://authors.library.caltech.edu/21217/1/CULaiaawfp84.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fred Culicks paper&lt;/a&gt;), the flow separation is apparent by the gradual decline of the lift curve slope shortly before maximum lift is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/81eqZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/81eqZ.png&quot; alt=&quot;Lift and Drag of the 1903 Wright Flyer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I added a red line on the drag curve on the left. It shows at which lift coefficient the ratio between lift and drag is minimized, and this again confirms that the lowest drag is possible at some intermediate lift coefficient. The lift coefficient of an airplane is proportional to the inverse of the airspeed squared, so this shows again that the lowest drag is attained at some intermediate speed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Drag increase after launch&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The attitude of the airplane on the track was approximately 0°. Note that the polar above gives an angle of attack between 2° and 5° for the flight condition. This means that the aircraft produced less lift while resting on the dolly and consequently less induced drag at the same airspeed. The friction drag of the dolly should be an order of magnitude smaller than the saving in induced drag due to the reduced angle of attack during acceleration. Only when the Flyer II pitched up at the end of the track it gained the lift needed to stay it in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another effect to consider is &lt;a href=&quot;https://aviation.stackexchange.com/questions/311/what-is-ground-effect&quot;&gt;ground effect&lt;/a&gt;. It lowers the induced drag component, and this effect should have helped to accelerate the Wright Flyer more while it was running along the track. Once it was airborne and had climbed some feet into the air, the speed would drop due to the climb and drag would increase due to the decreasing ground effect.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Propeller thrust over speed&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The second important force is the propeller thrust, of course. In case of the Flyer II, two pusher propellers were driven by an internal combustion engine of maybe 16 HP. The power output of an IC engine is constant regardless of the speed of the aircraft and increases linearly with RPM. When driving two large, fixed-pitch propellers, the engine speed will settle at the point where the torque output equals the torque to drive the propellers. This should give the Flyer II engine a tendency to run at higher RPMs the faster the aircraft flies. However, at some point the increased aerodynamic drag of the propellers will limit this RPM increase. Around this point, the propeller thrust will change with the inverse of airspeed, since propeller thrust is power divided by speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot below is pure guesswork, but should look similar to what the Flyer II was capable of. Thrust was marginal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hz1mg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hz1mg.png&quot; alt=&quot;Drag and Thrust over speed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generic plot of drag and thrust over speed with fixed propellers. The plane has two trim points, one unstable point close to stall and one stable point beyond the drag minimum. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Wind speed&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The last effect to consider is wind speed. When launching the Flyer II into a headwind, the airplane will have a higher airspeed at every point along the track and leave it at a higher speed than when being launched in calm wind. After launch, the aerodynamic drag increases suddenly as soon as the Flyer flies, and will increase again a little when it climbs. At these speeds, the thrust produced by the propellers will be roughly constant over airspeed - the details depend on the gearing and the engine characteristics. This means that the Flyer would be launched into the air at a point of its drag polar where drag in absolute terms was lower the more headwind was available, and the propeller thrust was not sufficient in calm air to sustain level flight. Only with the added speed possible in a headwind the Flyer could produce enough thrust to overcome the now lower drag and stay airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the lower headwind of 12 ft/s the plane lifted off with an airspeed of around 42 ft/s, just a bit above the slow trim point, and when it landed at the end of the field half a minute later, it had only accelerated to 48 ft/s, and the average speed over ground was only 33 ft/s. On another day with 17 ft/s headwind, the plane accelerated on the rail to maybe 47 ft/s and was well above the lower trim point at launch, so it could accelerate to the fast trim point reasonably quickly, which was maybe at 65 ft/s. Now the average speed over ground was 42 ft/s, giving the illusion that headwind made the aircraft faster. Had the flights taken longer, the speed difference between both days would had been smaller because the transient effect of the launch speed would had been smaller.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-02T20:12:36.540" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19535" PostTypeId="1" CreationDate="2015-08-31T23:22:41.920" Score="2" ViewCount="1373" Body="&lt;p&gt;How is rain that is encountered ABOVE the freezing level (altitude) not always &quot;freezing rain&quot;?  And how commonly does this occur? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Situation: Light rime ice in forecast (approximately 10-15K MSL(?)), so freezing level about 10K.  Climbout through forecast light rime and did not get any ice at all.  None.  Kept climbing, initially VMC but then encountered IMC somewhere around FL180(?) and then encountered rain.  (Been in snow once and this didn't look like snow.....BTW, no snow in forecast at all.  No freezing rain in forecast, either).  Smooth ride/no turbulence.  Kept climbing to get above rain due to altitude being above freezing level.  NO ice formation/accumulation at all.  Climbed all the way to FL280 before broke out of IMC/rain.  NO/ZERO ice accumulation.  How is this possible?   &lt;/p&gt;&#xA;" OwnerUserId="10042" LastEditorUserId="19" LastEditDate="2017-01-09T10:35:09.187" LastActivityDate="2017-01-13T11:10:46.783" Title="Why is rain above freezing level (altitude) not always &quot;freezing rain&quot;?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19536" PostTypeId="2" ParentId="19410" CreationDate="2015-09-01T00:01:23.450" Score="11" Body="&lt;p&gt;The reason for a different turn rate at higher altitude is because of the physics of Indicated (IAS) and True (TAS) airspeed. Many aircraft would find it impossible to do a standard rate turn at high altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A standard rate turn is 3° per second. This is also known as a two-minute turn because it would take 2 minutes to make a full 360, or 1 minute for a  180°, like each end of a holding pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bank angle required to make a 3°/sec turn is a function of TAS and bank angle. The formula is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$bank\,angle =\frac{turn\,rate\cdot TAS}{1091}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a standard rate turn at 170kn TAS requires a bank angle of 25°. As bank angle increases so do load factor and stall speed. A 25° bank yields a 10% increase in load factor and a 5% increase in stall speed. For this reason FAA and ICAO regulations require holding patterns to be standard rate, but not to exceed a 25° bank angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's where the altitude enters the equation. The relationship between TAS and IAS is dependent on air pressure and density. At 5000 feet in standard atmosphere an IAS of 160kn yields a TAS of 170kn. A standard turn at 170 KTAS would require the maximum bank angle of 25°. But in the thinner air at 14,000 that same 25° bank at 170 KTAS is only 142 KIAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So as altitude increases, a standard rate turn requires a slower IAS and a higher bank angle. At higher altitudes it would become impossible for many aircraft to make a standard rate turn without stalling. So at 14,000 feet the required turn rate is decreased to 2°/sec, which is a three minute turn (thus 90 seconds for a 180°). Where a standard turn at 14,000 IAS is limited to 142 KIAS, a 3 min turn can be performed up to 212 KIAS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason turn rate must be lowered at higher altitudes.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2017-03-13T02:46:39.153" LastActivityDate="2017-03-13T02:46:39.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19538" PostTypeId="1" AcceptedAnswerId="19549" CreationDate="2015-09-01T01:23:16.780" Score="16" ViewCount="40496" Body="&lt;p&gt;I have noticed for a while the A340 has four engines and the Boeing 777 only has two engines and they are about the same size. So why can't an A340 have two engines instead of four?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lmrYA.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lmrYA.png&quot; alt=&quot;A340&quot;&gt;&lt;/a&gt;&#xA;A340&lt;/p&gt;&#xA;&#xA;&lt;p&gt;.&lt;a href=&quot;https://i.stack.imgur.com/SZ6n6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SZ6n6.png&quot; alt=&quot;Boeing 777&quot;&gt;&lt;/a&gt; B777&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gyhBo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gyhBo.jpg&quot; alt=&quot;B747-8&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a jumbo jet like the B747-8 four engines are a requirement.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9276" LastEditDate="2015-09-01T11:32:19.447" LastActivityDate="2020-01-30T22:59:04.457" Title="Why does the A340 have 4 engines instead of 2?" Tags="&lt;airliner&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19539" PostTypeId="1" CreationDate="2015-09-01T01:31:20.840" Score="0" ViewCount="100" Body="&lt;p&gt;I am having a little trouble figuring out what these strange clouds are. You have a cloud forming off of a fighter jet when it breaks the sound barrier, but this is a different situation.&lt;a href=&quot;https://i.stack.imgur.com/4EQIz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4EQIz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1467" LastEditDate="2015-09-10T05:23:10.343" LastActivityDate="2015-09-10T05:23:10.343" Title="What are these strange clouds on the wing and how do they form?" Tags="&lt;airliner&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-09-01T03:30:24.230" ContentLicense="CC BY-SA 3.0" />
  <row Id="19540" PostTypeId="1" AcceptedAnswerId="19544" CreationDate="2015-09-01T01:35:56.677" Score="7" ViewCount="19489" Body="&lt;p&gt;Most aircraft contain systems which are used to mitigate problems which could be caused by ice. This includes everything from a heated pitot tube to a wing leading edge heated by bleed air. These systems are usually referred to as either deice or anti-ice systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between deice and anti-ice?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2015-09-01T15:30:06.440" LastActivityDate="2020-05-11T09:33:05.997" Title="What is the difference between deice and anti-ice?" Tags="&lt;aircraft-systems&gt;&lt;anti-ice&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19541" PostTypeId="1" CreationDate="2015-09-01T01:40:28.097" Score="5" ViewCount="272" Body="&lt;p&gt;My guess would be no because it does not reflect the air as well.&lt;a href=&quot;https://i.stack.imgur.com/5W1tt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5W1tt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Wingtip fence&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eUJ3D.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eUJ3D.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Winglet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I am basically asking is does the wing tip fence have the same amount of drag reduction (wing tip vortex) as the winglet?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-01T01:40:28.097" Title="Is the wingtip fence as effective as the winglet?" Tags="&lt;airliner&gt;&lt;winglets&gt;&lt;wing-tip-vortex&gt;" AnswerCount="0" CommentCount="1" FavoriteCount="1" ClosedDate="2015-09-01T05:35:03.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="19542" PostTypeId="2" ParentId="19535" CreationDate="2015-09-01T01:51:25.703" Score="4" Body="&lt;p&gt;The freezing altitude or $0\,^{\circ}\mathrm{C}$ isotherm is the altitude at which the temperature is $0\,^{\circ}\mathrm{C}$ in free atmosphere. This altitude varies and is usually only temporary as it depends on a number of factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sxACA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sxACA.png&quot; alt=&quot;Zero degree isotherm&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Iso0.png#/media/File:Iso0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Iso0&lt;/a&gt;&quot;. Licensed under CC BY-SA 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Freezing rain is a condition in which the water droplets become super-cooled (i.e. in liquid condition while below the freezing point of water) and freeze on coming to contact with cold surfaces. This condition happens when snow formed at altitude completely melts and supercools into large droplets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b5IEO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b5IEO.png&quot; alt=&quot;Freezing Rain&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.srh.noaa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be seen that, to form freezing rain, both warm and cold layers are required. One reason for not encountering freezing rain above the freezing line is that the temperature does not rise above the freezing point of water. In this case, we get snow or sleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rS9z1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rS9z1.png&quot; alt=&quot;Types of rain&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Ice_Storm_Chart.svg#/media/File:Ice_Storm_Chart.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ice Storm Chart&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:RicHard-59&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:RicHard-59&quot;&gt;RicHard-59&lt;/a&gt; based on image by J.R. Carmichael - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thought the above figure is for ground level, it applies for other altitudes also. The phenomenon of freezing rain is dangerous for airliners as the water droplets freeze on coming into contact with aircraft surfaces and can cause loss of lift among other problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O6p6x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O6p6x.jpg&quot; alt=&quot;SLD Ice&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Post-flight image shows ice contamination as a result of encountering Supercooled Large Droplet (SLD) conditions near Parkersburg, WV. Source: icebox.grc.nasa.gov&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="946" LastEditDate="2017-01-13T11:09:42.713" LastActivityDate="2017-01-13T11:09:42.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19543" PostTypeId="2" ParentId="19538" CreationDate="2015-09-01T01:57:02.820" Score="26" Body="&lt;p&gt;If it had only 2 engines, it would be an A330. The &lt;em&gt;main&lt;/em&gt; difference between the two models is that the A340 has four engines, and it was designed and produced specifically for airlines that needed that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the time the A330/A340 series was designed, having more than two engines was an operational benefit because a two-engined plane needs to stay within a certain range of diversion airfields, which made the A330 unsuitable for some routes. This benefit has since become smaller due to improved reliability of engines (or improved &lt;em&gt;trust&lt;/em&gt; in the reliability), since the maximal distance from nearest landing opportunity is determined mainly by how long time you dare to need a plane to stay aloft after an engine failure enroute, before the risk that the remaining engine will randomly fail too becomes unacceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A340s that are already built keep flying until they reach the end of their operational life, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only large quadjets still in production are the 747 and the A380. The A380 needs more than two engines because of its size, in order to produce enough takeoff thrust. The 747 might conceivably have ended up with two engines if it was designed from scratch today.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2015-09-01T01:57:02.820" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19544" PostTypeId="2" ParentId="19540" CreationDate="2015-09-01T02:11:00.927" Score="8" Body="&lt;p&gt;De-ice is a system that removes ice that has formed on a part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anti-ice is a system that prevents ice from forming on a part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A heated leading edge(bleed air) is an example of an anti-ice system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A inflatable boot on a leading edge is an example of a de-ice system.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-09-01T02:11:00.927" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19545" PostTypeId="2" ParentId="19531" CreationDate="2015-09-01T02:30:34.693" Score="5" Body="&lt;p&gt;A constant speed drive (CSD) converts the rotation from the accessory gearbox to a predetermined constant rotation rate.  The rate of the accessory gearbox is directly related to the high pressure spool (N2) rate and changes with power adjustments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CSD will ensure its rotation rate is constant.  The Challenger 604 CSD rotates at 12,000 RPM and outputs 115 V&lt;sub&gt;AC&lt;/sub&gt; @ 400 hertz.  Its max output is something like 30 kVA or kilovolts-amps.  Since we are talking AC power, it is not appropriate to call that watts.  The AC power is converted to 28 V&lt;sub&gt;DC&lt;/sub&gt; by the way of transformers called transformer rectifier units (TRU).&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="17780" LastEditDate="2016-11-12T17:59:19.987" LastActivityDate="2016-11-12T17:59:19.987" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19547" PostTypeId="2" ParentId="19500" CreationDate="2015-09-01T03:01:22.140" Score="3" Body="&lt;p&gt;There is a difference between total flight time and total time.  The FARs do not define total time but they do define a term called pilot time.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;61.1: Pilot time means that time in which a person—&#xA;      (i) Serves as a required pilot flight crewmember;&#xA;      (ii) Receives training from an authorized instructor in an aircraft, flight simulator, or flight training device; or&#xA;      (iii) Gives training as an authorized instructor in an aircraft, flight simulator, or flight training device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Total flight time is defined as&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.1: Flight time means:&#xA;  (1) Pilot time that commences when an aircraft moves under its own power for the purpose of flight and ends when the aircraft comes to rest after landing; or&#xA;  (2) For a glider without self-launch capability, pilot time that commences when the glider is towed for the purpose of flight and ends when the glider comes to rest after landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;61.51 deals with logging time.  In your first example, the airplane is type certificated for a single pilot, you are not performing any operation requiring more than one pilot (i.e. safety pilot) so you cannot log PIC, SIC.  I might log pilot time but not total flight time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your second example, while the non rated friend is flying you cannot log PIC or total flight time but may be able to log pilot time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You only need to worry about total time when applying for an ATP certificate as that certificate calls for total time not total flight time.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-09-01T03:01:22.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19548" PostTypeId="2" ParentId="19540" CreationDate="2015-09-01T03:16:48.160" Score="5" Body="&lt;p&gt;As the name indicates, anti-icing systems prevent the formation of ice (aircraft surfaces) while the de-icing systems remove the ice after it is formed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anti-icing systems can be active or passive. In general, most of the active anti-icing systems are thermal, which use the engine bleed air routed through the pipes in wings, engine intakes etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wyaOf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wyaOf.jpg&quot; alt=&quot;Anti icing system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: navyaviation.tpub.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another method of anti-icing is to have resistive circuits in wings, which can be generate heat when current is passed, preventing ice formation. This can be used also in de-icing mode to remove ice, which is more energy efficient compared to the anti-icing  mode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the oldest de-icing method was the pneumatic one, which uses an inflatable rubber boot to remove accumulated ice from leading edges of wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DSABZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DSABZ.png&quot; alt=&quot;Deicer Boots&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Deicer_(PSF).png#/media/File:Deicer_(PSF).png&quot; rel=&quot;noreferrer&quot;&gt;Deicer (PSF)&lt;/a&gt;&quot; by Pearson Scott Foresman - Archives of Pearson Scott Foresman, donated to the Wikimedia Foundation→This file has been extracted from another file: &lt;a href=&quot;//commons.wikimedia.org/wiki/File:PSF_D-240001.png&quot; rel=&quot;noreferrer&quot; title=&quot;File:PSF D-240001.png&quot;&gt;PSF D-240001.png&lt;/a&gt;.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-01T03:16:48.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19549" PostTypeId="2" ParentId="19538" CreationDate="2015-09-01T03:28:09.620" Score="29" Body="&lt;p&gt;The A340 was designed at a time when ETOPS (Extended-range Twin-engine Operational Performance Standards) had not been developed. Some airlines preferred two engines which reduced operational costs, while others preferred four engines with increased reliability at an additional cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus decided to split the development into distinct aircraft having the same wing and airframe - A330 with two engines and A340 with four engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as time has passed, ETOPS has become the norm with improved engine reliability, and A340 production has been stopped. Almost all the civil airliners under development now have two engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing 777, on the other hand, was developed with twin engine operation in mind. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9276" LastEditDate="2015-09-01T11:32:22.757" LastActivityDate="2015-09-01T11:32:22.757" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19550" PostTypeId="2" ParentId="19530" CreationDate="2015-09-01T04:00:12.537" Score="5" Body="&lt;p&gt;In general, there is a gap between the jet bridge (also called Passenger Boarding Bridges or PBB) and the aircraft. This is due to various reasons like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To prevent damage to the fuselage&lt;/li&gt;&#xA;&lt;li&gt;The jet bridge may not fit all the aircraft similarly as their fuselage dimensions are different.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;According to FAA Advisory Circular 150/5220-21C,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The PBB should be equipped with sensors to safely prevent&#xA;  dangerous contact with the aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The jet bridges at most airports are designed for larger passenger aircraft that are higher off the ground. When a small aircraft utilizes these jet bridges they must use a &quot;ramp&quot; to bridge the gap between the jet bridge and the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the same Circular, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The maximum horizontal gap allowable along the path to the aircraft can be no&#xA;  greater than 1.25 in (32 mm)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, I guess that a 4 inch gap is not allowed. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-01T04:00:12.537" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19552" PostTypeId="1" AcceptedAnswerId="19553" CreationDate="2015-09-01T10:59:11.733" Score="8" ViewCount="4576" Body="&lt;p&gt;When the emergency doors over the wings are opened do the wings automatically lower themselves, to allow passengers to slide and reach the ground? Or does the pilot have to do it from the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="3945" LastEditDate="2015-09-01T17:38:43.853" LastActivityDate="2015-09-02T09:36:19.040" Title="Does opening of emergency doors over wings, lead to automatic lowering of the aircraft's wings?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="19553" PostTypeId="2" ParentId="19552" CreationDate="2015-09-01T11:01:24.100" Score="18" Body="&lt;h2&gt;Wings are static.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The wings do not move in response to emergency door opening. There is no requirement regarding position of flaps, in most cases involving an emergency evacuation after landing, flaps are likely to be extended, but I don't think this is guaranteed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Evacuation assistance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;On commercial transport aircraft, there are marked routes on the wing for passengers and, if the exit point is more than 6ft from the ground, there are self-inflating slides that allow passengers to reach the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TclAx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TclAx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;https://www.youtube.com/watch?v=4Xu9XRHyGNc&quot; rel=&quot;noreferrer&quot;&gt;video by &quot;Airline_Alex&quot;&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Evacuation on water&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The inflated slides also work as life-rafts in the event that the aircraft comes to rest in water and has to be evacuated. Generally this applies only to slides at main exits, over-wing exits have slides that are not designed to be used in this way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F8jTW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F8jTW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;sup&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;US 1549&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Regulations&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=9ddb4757a29c0e7ab8c4dcfacc93c21b&amp;amp;r=APPENDIX&amp;amp;n=14y3.0.1.1.8.13.3.6.26&quot; rel=&quot;noreferrer&quot;&gt;regulations in the USA&lt;/a&gt; say&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each passenger-carrying landplane emergency exit (other than over-the-wing) that is more that 6 feet from the ground with the airplane on the ground and the landing gear extended must have an approved means to assist the occupants in descending to the ground. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The manufacturer must demonstrate that they can evacuate all passengers and crew to the ground within 90 seconds using only half the emergency exits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This applies to aircraft capable of carrying more than 44 passengers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Variations in arrangements by aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Not all aircraft need overwing exits and slides. Here are some B757 variants&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PbF0C.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PbF0C.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/TMRFs.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TMRFs.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AoMFs.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AoMFs.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;From &lt;a href=&quot;http://www.crjresets.ca/z-Mcon/Hard2Find/B757/757_rr/airplane_general/doors_and_windows.htm&quot; rel=&quot;noreferrer&quot;&gt;CRJ Resets&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Boeing 737&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As commenters have noted, the 737 does not have self-inflating slides for its over-wing exits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WcCI4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WcCI4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.psafetycards.com/qs.htm&quot; rel=&quot;noreferrer&quot;&gt;Pessini&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 system does not always work very well&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passengers climbed onto both wings, which&#xA;  were slippery due to the rain, but were able to see&#xA;  the markings indicating the direction of movement. It&#xA;  was difficult to see the ground in the dark and some&#xA;  passengers were not aware that they should slide down&#xA;  the flap surfaces. Others expected to find an escape&#xA;  slide. On the left wing, some passengers slid down&#xA;  onto the ground and assisted others. On the right&#xA;  wing, fewer people slid down to the ground, while&#xA;  others re‑entered the cabin and exited it using door&#xA;  escape slides when it was apparent that there were no&#xA;  visible signs of danger.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;- from &lt;a href=&quot;https://www.gov.uk/aaib-reports/boeing-737-804-g-gdfj-19-october-2012&quot; rel=&quot;noreferrer&quot;&gt;AAIB report&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-09-02T09:36:19.040" LastActivityDate="2015-09-02T09:36:19.040" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="19554" PostTypeId="1" AcceptedAnswerId="19564" CreationDate="2015-09-01T11:30:41.980" Score="11" ViewCount="1641" Body="&lt;p&gt;I have just seen a 707 depart from HTDA Dar es Salaam that has the tail painted with the Boeing colors. Any idea of who the plane belongs to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Livery like this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FS3Rg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FS3Rg.jpg&quot; alt=&quot;777 in Boeing colors&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously 707 instead of 777 painted on it.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="22726" LastEditDate="2018-05-25T18:28:48.423" LastActivityDate="2018-05-25T18:28:48.423" Title="Who operates a 707 with Boeing factory livery?" Tags="&lt;livery&gt;&lt;boeing-707&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19555" PostTypeId="1" CreationDate="2015-09-01T11:33:51.373" Score="2" ViewCount="512" Body="&lt;p&gt;Should one maintain a constant attitude if he wants to hold a constant speed or does the attitude vary depending upon the wind direction?&lt;/p&gt;&#xA;" OwnerUserId="10047" LastEditorUserId="595" LastEditDate="2015-09-01T11:37:11.247" LastActivityDate="2017-06-04T22:33:59.790" Title="For the same airspeed does the attitude of an airplane change with varying wind directions?" Tags="&lt;aerodynamics&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19556" PostTypeId="2" ParentId="19555" CreationDate="2015-09-01T11:48:02.700" Score="0" Body="&lt;p&gt;If the change is in direction, the airplane will change its yaw (also known as heading) angle, so that the track angle (the direction along which it is travelling) does not change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more informations about the differences between heading, track and similar angles, you can read &lt;a href=&quot;https://aviation.stackexchange.com/q/8000/1467&quot;&gt;this other question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-01T11:48:02.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19557" PostTypeId="2" ParentId="19555" CreationDate="2015-09-01T11:52:17.067" Score="1" Body="&lt;p&gt;The lift generated is proportional to the airspeed and the angle of attack (amongst other factors).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the wind direction changes, the aircraft will maintain a constant airspeed, by increasing or decreasing power.  To maintain level flight, by maintaining the same lift, the angle of attack, for the given weight and altitude, will remain constant therefore there is no attitude change.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-01T12:38:56.597" LastActivityDate="2015-09-01T12:38:56.597" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19558" PostTypeId="1" CreationDate="2015-09-01T11:54:14.927" Score="4" ViewCount="139" Body="&lt;p&gt;Do you know of any real life cases, when invalid FMS data affected somehow the flight operations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By invalid FMS data I mean a case, when the procedure coding does not reflect properly the original procedure as published by state's AIP service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/19386/what-happens-with-rnav-procedures-on-the-way-from-aip-publication-to-fms-databas&quot;&gt;What happens with RNAV procedures on the way from AIP publication to FMS database&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9982" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-11-11T13:32:47.470" Title="Are there any examples (real life cases) of invalid FMS data affecting flight operations?" Tags="&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19559" PostTypeId="2" ParentId="8168" CreationDate="2015-09-01T12:00:30.913" Score="2" Body="&lt;p&gt;Pressure-altitude is defined in ICAO Chicago Convention, &lt;a href=&quot;http://www.icao.int/Meetings/anconf12/Document%20Archive/an02_cons%5B1%5D.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;annex 2 - Rules of the Air&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pressure-altitude. An atmospheric pressure expressed in terms of&#xA;  altitude which corresponds to that pressure in the Standard&#xA;  Atmosphere.*&#xA;  * As defined in Annex 8&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.spilve.lv/library/airlaw/Annex%208.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Annex 8 - Airworthiness of Aircraft&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NoHY3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NoHY3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;......&lt;a href=&quot;https://i.stack.imgur.com/JjRSc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JjRSc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-09-01T12:00:30.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19560" PostTypeId="2" ParentId="19558" CreationDate="2015-09-01T12:39:49.860" Score="2" Body="&lt;p&gt;Here is some old material used in Europe to prepare for the transition from AIS to AIM: &lt;a href=&quot;http://www.icao.int/safety/information-management/Transition%20Library%20for%20AIM/Documentation/Legal%20and%20Institutional%20Issues.pdf&quot; rel=&quot;nofollow&quot;&gt;AIS to AIM: Enabling the Net-Centric Information Environment&lt;/a&gt; by Roderick van Dam, Head of Eurocontrol Legal Service. The document references two legal cases where navigational data and hardware were involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pakistan International Airlines&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Bejon v. Pakistan International  Airlines (Toulouse Court of &#xA;  Appeal, 1998) Liability of Jeppesen raised.  Jeppesen argued that&#xA;  approach map  was based on map provided by States.  Court concluded&#xA;  that map was  technically acceptable This case confirmed  the risk&#xA;  related to  the publication of Aeronautical data.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More: &lt;a href=&quot;https://en.wikipedia.org/wiki/PIA_Flight_268&quot; rel=&quot;nofollow&quot;&gt;PIA Flight 268&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;American Airlines&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;American Airlines v. Jeppesen- Anderson and Honeywell (US Federal &#xA;  Court, 2000) The Accident Report had concluded: the probable causes&#xA;  of the accident were  related to failures of  the flight crew; &#xA;  contributing factor was related to FMS-generated navigational&#xA;  information; AA blamed the Jeppesen software in the  Honeywell&#xA;  computer; alleged that products  helped caused the crash; A Federal&#xA;  Jury found  that Jeppesen was  17% at fault and Honeywell 8 % at&#xA;  fault.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;More: &lt;a href=&quot;https://en.wikipedia.org/wiki/American_Airlines_Flight_965&quot; rel=&quot;nofollow&quot;&gt;American Airlines Flight 965&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-09-01T12:39:49.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19561" PostTypeId="2" ParentId="19555" CreationDate="2015-09-01T13:02:28.723" Score="2" Body="&lt;p&gt;If by attitude you mean pitch attitude or angle of attack (which is how I automatically understood this), no it does not change as this is related to the aircraft's airspeed through the air. So an aircraft flying downwind will have the same AOA as the same aircraft at the same airspeed flying upwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to fly at the same groundspeed upwind as downwind, then you would have to vary your airspeed, which means varying you pitch attitude or AOA. This might not be possible if say you were in a light aircraft in a 40 knot wind at altitude which cruises at 100 knots.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-09-01T13:02:28.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19562" PostTypeId="1" AcceptedAnswerId="19563" CreationDate="2015-09-01T14:27:29.403" Score="4" ViewCount="242" Body="&lt;p&gt;If the &lt;a href=&quot;https://aviation.stackexchange.com/questions/17548/what-areas-of-a-commercial-airliner-are-pressurized-besides-the-cabin&quot;&gt;baggage compartment is always pressurized&lt;/a&gt;, why pets can be brought only to select flights and not all flights?&lt;/p&gt;&#xA;" OwnerUserId="2560" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-01T14:57:41.963" Title="Why pets are allowed only on select flights?" Tags="&lt;airliner&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19563" PostTypeId="2" ParentId="19562" CreationDate="2015-09-01T14:57:41.963" Score="5" Body="&lt;p&gt;The USDOT has a list off things related to this &lt;a href=&quot;http://airconsumer.ost.dot.gov/publications/animals.htm&quot; rel=&quot;noreferrer&quot;&gt;matter here&lt;/a&gt; but there are many factors.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;International Travel:&lt;/strong&gt; Since flights often go between countries that also means they cross jurisdictions. Many countries have varying laws on importing and exporting different animals. As such airlines may not always allow you to carry animals since it may not be legal.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Contamination:&lt;/strong&gt; Animals can carry a wide variety of disease and other things. An airline my chose to not carry animals to avoid any potential issues. Even if in the cargo hold it can not be guaranteed that the animals fur wont come in contact with another passengers baggage. If that passenger had an allergy to that type of fur they may later have an issue.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Food:&lt;/strong&gt; Placing an animal in the baggage hold prevents anyone from effectively feeding the animal which the DOT does seem to have some regulations on for longer flights.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Temperature:&lt;/strong&gt; Although it is pressurized the baggage compartment is by no means warm. This prevents a potentially dangerous situation for animals as well.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;As for bringing an animal on the plane (aside from service animals which are not considered animals). It would seem that the FAA leaves this specific matter up to the airlines. According to &lt;a href=&quot;https://www.faa.gov/passengers/fly_pets/cabin_pets/&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt; when it comes to&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;What are the FAA rules regarding traveling with pets in the passenger cabin?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The Federal Aviation Administration (FAA) allows each airline to decide if they will allow you to travel with your pet in the passenger cabin. If an airline does allow you to bring your pet into the cabin, we consider your pet container to be carry-on baggage and you must follow all carry on baggage rules (14 CFR part 121, section 121.589):&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-01T14:57:41.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19564" PostTypeId="2" ParentId="19554" CreationDate="2015-09-01T15:16:00.877" Score="15" Body="&lt;p&gt;&lt;strong&gt;Official airplane of Democratic Republic of Congo&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Democratic_Republic_of_the_Congo&quot; rel=&quot;nofollow noreferrer&quot;&gt;Democratic Republic of Congo&lt;/a&gt; uses a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;nofollow noreferrer&quot;&gt;B707-138B&lt;/a&gt;, registered 9Q-CLK: LK for Laurent Kabila.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Laurent-D%C3%A9sir%C3%A9_Kabila&quot; rel=&quot;nofollow noreferrer&quot;&gt;Laurent Kabila&lt;/a&gt; has been Congo's President until his assassination (he was succeeded by his son).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an airplane with a &lt;a href=&quot;http://www.adastron.com/707/qantas/VH-EBG.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;long history&lt;/a&gt; (and some controversy). She has now &lt;code&gt;707&lt;/code&gt; painted on the tail, but not the &lt;code&gt;Boeing&lt;/code&gt; markings. Thanks to our friends at &lt;a href=&quot;http://www.airliners.net/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt; several pictures are available:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UiO5t.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UiO5t.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(source: &lt;a href=&quot;http://www.airliners.net/photo/Boeing-707-138B/2532333/&amp;amp;sid=2cb052bc2441fd592494c5145153691e&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net, Mark. Szemberski&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once this a/c had no logo at all, here in 2008:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rOFYT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rOFYT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(source: &lt;a href=&quot;http://www.airliners.net/photo/Boeing-707-138B/1384256/&amp;amp;sid=2cb052bc2441fd592494c5145153691e&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net, Weimeng&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Youtube too: &lt;a href=&quot;https://www.youtube.com/watch?v=8rrC3Zwn5vs&quot; rel=&quot;nofollow noreferrer&quot;&gt;B707 9Q-CLK &lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Qantas in the past&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back in 1959 when it entered service at Qantas as &lt;a href=&quot;http://www.aussieairliners.org/b-707q/vh-ebg/vhebg.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;VH-EBG&lt;/a&gt;, the first B707 with a 5th engine in a pod-pak:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i2uXj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i2uXj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(source: &lt;a href=&quot;http://www.aussieairliners.org/b-707q/vh-ebg/4605.234.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Qantas Heritage Collection&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More on the curious &lt;a href=&quot;https://aviation.stackexchange.com/questions/19566/what-is-a-pod-pak&quot;&gt;engine exhaust and the pod-pak&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-03-03T12:54:28.217" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="19566" PostTypeId="1" AcceptedAnswerId="19567" CreationDate="2015-09-01T17:00:27.787" Score="18" ViewCount="2306" Body="&lt;p&gt;The following image, from the Qantas Heritage Collection (via &lt;a href=&quot;http://www.aussieairliners.org/b-707q/vh-ebg/4605.234.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;aussieairliners.org&lt;/a&gt;), shows the flight crew inspecting the 'Pod-Pak' prior to departure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z6Eji.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z6Eji.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the angle of their heads, I'd assume it's the engine-looking device to the right of frame. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what are the rocket engine-like tubes at the left of frame?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2017-05-30T19:51:51.547" LastActivityDate="2017-05-30T19:51:51.547" Title="What is a &quot;Pod-Pak&quot;?" Tags="&lt;airliner&gt;&lt;boeing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19567" PostTypeId="2" ParentId="19566" CreationDate="2015-09-01T17:18:57.067" Score="22" Body="&lt;p&gt;A Pod-Pak is a aerodynamically shaped enclosure to transport an extra engine under the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://books.google.nl/books?id=G1ujXqwsDcUC&amp;amp;pg=PA14&amp;amp;lpg=PA14&amp;amp;dq=pod%20pak%20engine&amp;amp;source=bl&amp;amp;ots=VoF_L-4wNM&amp;amp;sig=PP5E7s9cwvdCdXGTGIIwtRmrL3Q&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0CCcQ6AEwAWoVChMI2MG57qnWxwIVaZrbCh1MqQC5#v=onepage&amp;amp;q=pod%20pak%20engine&amp;amp;f=false&quot;&gt;'Flying Magazine', Nov 1959:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Spare engine in “Pod Pak” is the airlines' modern method of&#xA;  transporting extra engines to maintenance points. Nine major airlines&#xA;  flying Boeing 707s have ordered Pod-Paks. This spare suspended below&#xA;  the wing of a Qantas Airline's 707 shows the Pod Pak suspended from&#xA;  the airplane's front wing spar by means of two fittings and to the&#xA;  landing geard support rib by four bolts. Fairings streamline ends of&#xA;  the engine and normal engine cowls enclose the sides. No structural&#xA;  changes are required in the airplane's wing and, when not needed,&#xA;  Pod-Pak can be removed completely.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The exhaust pipes of the Pratt &amp;amp; Whitney JT3C turbojet engine on the left of the picture are an attempt to reduce the noise of the engine. They should aid in the mixing of the core exhaust stream and the freestream air which is quite a noisy process. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The successor to the JT3C, the JT3D, was a turbofan. In a turbofan there is a layer of bypass air between the core exhaust stream and the freestream which reduces the noise and increases the efficiency. Later B707s fitted with the JT3D engines did have not have the 20 pipes exhaust. Most of the aircraft which were originally fitted with the JT3C where later retrofitted with the JT3D. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-01T19:30:23.577" LastActivityDate="2015-09-01T19:30:23.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19568" PostTypeId="1" AcceptedAnswerId="19570" CreationDate="2015-09-01T18:39:00.003" Score="37" ViewCount="18627" Body="&lt;p&gt;Every time I pass by Munich I have to pay a visit to the Deutsches museum, in particular to the aviation wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among the other aircraft on display, there is a &lt;a href=&quot;http://www.deutsches-museum.de/sammlungen/verkehr/luftfahrt/propellerflugzeuge/ab-1918-bis-1945/junkers-ju-52/&quot; rel=&quot;noreferrer&quot;&gt;Junkers Ju-52&lt;/a&gt;. A different photo taken from &lt;a href=&quot;http://wellisntthisabitglorious.com/?attachment_id=308&quot; rel=&quot;noreferrer&quot;&gt;a different website&lt;/a&gt; illustrates well what caught my attention:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aMlGT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aMlGT.jpg&quot; alt=&quot;Lufthansa Ju-52&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are the external surfaces of both wing and fuselage corrugated?&#xA;Were the designers hoping to achieve some performance improvement through this choice? Are there any papers/documents about this?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="9276" LastEditDate="2015-09-02T13:29:24.970" LastActivityDate="2017-09-29T15:00:00.473" Title="Why did the Junkers Ju-52 have corrugated external surfaces?" Tags="&lt;aerodynamics&gt;&lt;aviation-history&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19569" PostTypeId="1" CreationDate="2015-09-01T18:40:57.600" Score="21" ViewCount="26777" Body="&lt;p&gt;Reading about the Airbus E-Fan and it's &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_E-Fan#Specifications&quot;&gt;dual 30 kW thrust fans&lt;/a&gt; caused me to wonder: assuming the need for four electric fans, how many kilowatts would be required to power each fan with enough thrust to get a Boeing 747-8 airborne?&lt;/p&gt;&#xA;" OwnerUserId="10049" LastActivityDate="2019-09-17T06:58:11.017" Title="How many kilowatts to get an electric 747-8 airborne?" Tags="&lt;electric-engine&gt;&lt;boeing-747&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="19570" PostTypeId="2" ParentId="19568" CreationDate="2015-09-01T18:47:24.963" Score="28" Body="&lt;p&gt;It was largely a structural decision. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Ford_Trimotor&quot;&gt;Ford Tri-Motor&lt;/a&gt; which was designed to mimic many things the Junkers plane designs included, including the corrugated metal. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...all of which were constructed of aluminum alloy, which was corrugated for added stiffness, although the resulting drag reduced its overall performance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Corrugated metal is common for roof panels and ironically, hangars, these days. You can find some info on the strength and flex properties of it when related to those topics. Here is an &lt;a href=&quot;http://www.eng-tips.com/viewthread.cfm?qid=394085&quot;&gt;interesting thread&lt;/a&gt; on increased drag (and load) on corrugated roofs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the availability of the material vs sheet aluminum I would argue that it had little effect on the design choice. Keep in mind all corrugated aluminum starts out as sheet aluminum at some point in the line so its hard to say there is more than one or either material. On top of that it takes more corrugated material to cover a specific square area than flat sheet material which would drive the price up. At that time period in aviation a lot of experimenting was going on and anything that made a plane a bit stronger or a bit faster was considered quite an achievement. Keep in mind we are coming of the tails of the fabric plane era so a design like this would have seemed revolutionary. The Ju-52/3m (the one you have pictured) came out in 1932 (work began in '28), by that time other makers were already looking at and working on smooth aluminum body planes. There is of course a large social aspect to the availability of materials at this time in history especially in Germany. I will refrain form a full history lesson here but you can read up on &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers&quot;&gt;Junkers history here&lt;/a&gt; and about the man him self &lt;a href=&quot;https://en.wikipedia.org/wiki/Hugo_Junkers&quot;&gt;Hugo Junkers here&lt;/a&gt; which include some of his political views and his involvement (and issues with) the Nazi party. His work in all metal designs is credited with inspiring many passenger planes in the post WW1 and WW2 eras of design.      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1467" LastEditDate="2015-09-02T18:38:17.823" LastActivityDate="2015-09-02T18:38:17.823" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19571" PostTypeId="2" ParentId="19569" CreationDate="2015-09-01T18:53:00.657" Score="7" Body="&lt;p&gt;Well, the GEnx-2B67 engines with which the 747-8 is fitted each produce a maximum of $ 284 \mathrm{kN}$ thrust (according to its Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx#General_characteristics&quot; rel=&quot;noreferrer&quot;&gt;page&lt;/a&gt;). This translates to a total of $1136\mathrm{kN}$, since it has 4 engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power, which has the units Watt, is the product of force (thrust) and velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747 has a takeoff speed of about $290 \mathrm{km/h}$, according to &lt;a href=&quot;http://www.aerospaceweb.org/question/performance/q0088.shtml&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; page.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the 747 requires all its available thrust for takeoff, the power it requires can be found by multiplying its velocity by the force pushing it forward (in the case of an airplane, its thrust).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First convert these to SI units:&#xA;$$1136 kN = 1136000 N$$&#xA;$$290 km/h = 80.55 m/s$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We now multiply these to get the power:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ P = 1136000 \cdot 80.55 = 91504800 W = 91.5 MW $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, for takeoff, the 747-8 will require approximately $91.5 \mathrm{MW}$ of power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a very crude estimate. Firstly, the maximum thrust listed on the engine's Wikipedia page is likely its maximum static thrust, when it is standing still. When it is moving forward at $290 \mathrm{km/h}$ at takeoff, this thrust will be slightly less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if you want to provide this power with electric motors and fans, there are inefficiencies associated with both the electric motors and the fans, which will mean that the actual motors used will in total need to be able to produce quite a bit more than $91.5 \mathrm{MW}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The weight of such motors will be monumental. And these motors will need to be fed by an energy source, batteries or hydrogen fuel cells come to mind, and the weight of these will be just as large.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electric motors are quite efficient in converting energy, but the energy storage devices that will feed them have very low energy densities (read energy per weight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Internal combustion engines are quite inefficient in converting energy, but the fossil fuels that they use have an extremely high energy density.&lt;/p&gt;&#xA;" OwnerUserId="2355" LastEditorUserId="4197" LastEditDate="2015-09-02T07:53:47.307" LastActivityDate="2015-09-02T07:53:47.307" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="19572" PostTypeId="2" ParentId="19568" CreationDate="2015-09-01T18:53:12.277" Score="23" Body="&lt;p&gt;The corrugated skins on the JU-52 are a strengthening/stiffening measure: Corrugated skins are less prone to bending when loaded along the corrugation (the same reason we use &lt;a href=&quot;https://en.wikipedia.org/wiki/Corrugated_fiberboard#Properties&quot; rel=&quot;noreferrer&quot;&gt;corrugated boxes&lt;/a&gt; for shipping).&lt;br&gt;&#xA;While there are likely some aerodynamic penalties as a result of this, small corrugations could be within the boundary layer and the overall trade-off between weight (to brace and stiffen the skin internally) versus aerodynamics may be favorable in some designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of corrugated aluminum skins is not exclusive to the JU-52: &lt;a href=&quot;https://en.wikipedia.org/wiki/Ford_Trimotor&quot; rel=&quot;noreferrer&quot;&gt;the Ford Trimotor&lt;/a&gt; also used corrugated skin.&#xA;In modern designs the flight control surfaces of Piper's PA-28 family of aircraft are also corrugated - though far less dramatically, with stamped indentations to provide stiffness in lieu of internal bracing:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/yuF6a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yuF6a.jpg&quot; alt=&quot;PA-28 Tail &amp;amp; flap corrugation visible&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-01T18:53:12.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19573" PostTypeId="2" ParentId="19552" CreationDate="2015-09-01T20:14:47.213" Score="8" Body="&lt;p&gt;There are &lt;em&gt;no transport aircraft where the wings would be movable&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if you meant &lt;em&gt;flaps&lt;/em&gt;, the question would make sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most aircraft the overwing exits are equipped with inflatable slides that inflate aft over the wing trailing edge (see the image in the other answer). However in some aircraft it is indeed intended that the escaping persons will slide down the flaps, most notably on Boeing 737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZS0bG.jpg&quot; alt=&quot;Boeing 737-800 evacuation procedures&quot;&gt;&lt;br&gt;&#xA;(copied from &lt;a href=&quot;https://aviation.stackexchange.com/a/2461/524&quot;&gt;this answer&lt;/a&gt;, the original &lt;a href=&quot;http://flight72.storenvy.com/collections/132463-safety-cards/products/120964-delta-airlines-boeing-737-800-safety-card&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt; seems unfortunately dead)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, the flaps &lt;em&gt;don't move automatically&lt;/em&gt;. The pilots have to extend them. Worse, the flaps require power to move and they move rather slowly, so they may not extend all the way due to lack of time or failure of the necessary systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen some incident report involving evacuation where it was mentioned that the flaps were not extended all the way down due to lack of time, but I don't remember enough details to find the reference now. &lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-01T20:14:47.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19574" PostTypeId="2" ParentId="19568" CreationDate="2015-09-01T21:32:41.060" Score="26" Body="&lt;p&gt;The corrugated surfaces helped to save weight and drag, and they were readily available at the time. Today we would probably use sandwich panels for the same reasons, but 100 years ago those were not available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the world's first all-metal airplane used already corrugated panels for the wing, while Junkers' first all-metal design was made from sheet steel. The aluminum panels for the wing and elevator of the Reissner-Ente were made in Junkers' factory and delivered to his colleague, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hans_Reissner&quot; rel=&quot;noreferrer&quot;&gt;Prof. Reissner&lt;/a&gt;, in 1912.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ppMFl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ppMFl.jpg&quot; alt=&quot;Reissner-Ente&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Reissner-Ente from 1912. Flying direction is to the right.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the war broke out, Junkers felt he needed to contribute and started to build monoplanes with cantilever wings from 0.2mm steel sheets with corrugated panels welded below the smooth outer skin. The corrugated substructure worked much like the core in corrugated cardboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HTUOU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HTUOU.jpg&quot; alt=&quot;Junkers J-1&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Junkers J-1 from 1915 (picture &lt;a href=&quot;http://www.junkers.de/flugzeuge/flugzeugbau/flugzeuge_des_ersten_weltkrieges&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unsurprisingly, this lead to flyable, but very heavy aircraft. To lower the weight of his designs, Junkers reduced the skin to the corrugated panels and did away with the smooth skin on top, and he switched from steel to aluminum, a material which he initially avoided to reduce cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The low power of the engines of that time demanded low wing loadings, and surface friction was a minor contribution to the overall drag of aircraft of this time. Junkers monoplanes were the fastest fighters around, since they had no bracing wires. An additional benefit in the war for independence of the Baltic states during 1919 was their robustness - the fast shifting front lines made solid hangars impossible, and wooden airplanes were unusable after rain, so on many days only Junkers airplanes could take to the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xBoJa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xBoJa.jpg&quot; alt=&quot;Junkers J-9&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Junkers J-9 (picture by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Threecharlie&quot; rel=&quot;noreferrer&quot;&gt;Threecharlie&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If Junkers had wanted to reduce drag more, he would had made the landing gear retractable. But that would had added weight, just like a smooth layer on top of the corrugated one, and would had increased induced drag and had made the aircraft more expensive. The best compromise was to leave the corrugated surface exposed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By 1932, when the Ju-52 flew first, this technique was already past its prime: Engine performance, construction techniques and wing loading had improved to a point that the better solution was to rivet stiffeners on the inside of a load-carrying skin. Junkers airplanes were very innovative first, but once the company had found a good way of producing robust, low-cost aircraft, it stuck to what it knew. However, Junkers' concept of a steel or aluminum truss plus the corrugated skin was heavier than the smooth monocoque skin which we still use on today's airplanes, and once aerodynamic drag could be reduced to a point where the drag increase due to the larger wetted surface of the corrugated skin could not be overlooked, even Junkers switched over. The Ju-52 was the last (and most successful) of the traditional Junkers aircraft, and the next one, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_86&quot; rel=&quot;noreferrer&quot;&gt;Ju-86&lt;/a&gt;, used the more expensive, but lighter monocoque design. Note that it had a retractable landing gear, but kept the Junkers Doppelflügel (the offset flaps and ailerons).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z2aEi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z2aEi.jpg&quot; alt=&quot;Ju-86 airliner of South African Airways&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Ju-86 airliner of South African Airways (picture by Etienne du Plessis / &lt;a href=&quot;https://www.flickr.com/photos/8270787@N07/3545139363&quot; rel=&quot;noreferrer&quot;&gt;Flickr.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-11-09T20:37:45.667" LastActivityDate="2016-11-09T20:37:45.667" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19575" PostTypeId="2" ParentId="19191" CreationDate="2015-09-01T21:33:19.707" Score="3" Body="&lt;p&gt;It looks like there have been several attempts at coming up with viable HUDs for light singles but none have, well, taken off (business jets are a &lt;a href=&quot;http://www.embraerexecutivejets.com/en-us/jets/legacy-500/pages/technology.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;different story&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The VirtualHUD company mentioned in &lt;a href=&quot;http://www.gizmag.com/virtualhud-propeller-projector-hud/12065/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt; doesn't exist any more&lt;/li&gt;&#xA;&lt;li&gt;The G-HULP exists and &lt;a href=&quot;http://www.aircraftspruce.com/categories/avionics_instruments/av/menus/in/hud.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;you can buy it&lt;/a&gt; but I couldn't find any useful information about it or even the manufacturer's website&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since there's really nothing much out there, it suggests that HUDs for light singles are too expensive for typical pilots and/or just not useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cost is always relative, but the standalone G-HULP &lt;a href=&quot;http://www.aircraftspruce.com/catalog/inpages/patavionghulp2.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;costs USD 6,000&lt;/a&gt; and that has to be compared to other, potentially more useful things like avgas (i.e. flying time!), avionics upgrades, ADS-B or just general maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even if a GA pilot has nothing better to spend his money on, it isn't clear that HUDs are actually as useful as you might think. &lt;a href=&quot;http://www.flyingmag.com/pilots-places/pilots-adventures-more/going-direct-hud-vs-combined-vision&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; looks at a new Honeywell system for business jets that overlays a HUD view on the PFD, and they compared the landing precision of 'heads-up' (traditional HUD) vs. 'heads-down' (HUD on the PFD) pilots:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A chart that showed landing points at the end of approaches flown by&#xA;  pilots using the two systems showed scattershot points with no&#xA;  apparent bias toward either system. Both systems allowed their pilots&#xA;  to fly very accurate approaches.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This result, Ververs says, surprised the pilots in the study who had a&#xA;  lot of HUD time going into the testing. They had all assumed, she&#xA;  says, that the HUD would be the better technology. As far as the&#xA;  testing experience could show, it wasn’t better [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course that's only one specific testing scenario, but it's a very critical one because landings are when you really need to see and react quickly. Personally, I'm not convinced that focusing my eyes &lt;em&gt;on&lt;/em&gt; the HUD for airspeed and then &lt;em&gt;through&lt;/em&gt; the HUD to the runway would be any quicker or easier than just flicking my eyes between the airspeed indicator and the runway centerline. (Jan Hudec made the &lt;a href=&quot;https://aviation.stackexchange.com/questions/19191/are-hud-systems-available-for-light-ga-aircraft/19575#comment45091_19575&quot;&gt;comment&lt;/a&gt; that focusing shouldn't be an issue with a &quot;good&quot; HUD, so this may not be an issue at all, at least in theory.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And there are probably other issues with a HUD too, like making an instrument scan more complex; making the pilot focus his vision on the HUD rather than into the distance; or just being a general distraction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an interesting alternative concept to a fixed HUD, by the way: &lt;a href=&quot;http://glass.aero/&quot; rel=&quot;nofollow noreferrer&quot;&gt;wearable tech&lt;/a&gt;. Whether it's any more successful remains to be seen.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-02T13:05:30.913" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19576" PostTypeId="1" CreationDate="2015-09-01T22:06:15.567" Score="12" ViewCount="14174" Body="&lt;p&gt;When an aircraft is being stored in a hangar between flights, are there any requirements to have the aircraft connected to an earth ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that there is (although I'm looking for the reference), and if so, why and how should this be accomplished?  Is attaching a cable to the metal structure of the hangar an accepted practice?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="19" LastEditDate="2016-07-14T08:43:36.120" LastActivityDate="2019-07-09T08:18:38.433" Title="What are the requirement for electrical grounding of aircraft in hangar storage?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;ground-operations&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19577" PostTypeId="1" AcceptedAnswerId="19583" CreationDate="2015-09-01T22:51:31.220" Score="4" ViewCount="274" Body="&lt;p&gt;I want to double check if my first step in obtaining a sport, recreational, or private license is to obtain a student license.  I'm assuming student license always comes first, but want to make sure.  :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to make sure that isn't a less expensive way to go than this -- jumping into a more intensive program to go &quot;straight&quot; to the higher level licenses.  Want to make sure getting a student license first doesn't financially waste some of the classes, training, or flight hours you pay for -- by them not counting toward the higher level licenses -- where if you had done it differently you would have saved money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not talking about less learning, just how it's done.  (Making sure high enough licensed instructors, right classes, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an addition... Do you jump through student, sport, recreational, to private?  Or, do you go from student which whichever of these you want?&lt;/p&gt;&#xA;" OwnerUserId="10052" LastEditorUserId="3386" LastEditDate="2015-09-03T04:20:54.317" LastActivityDate="2015-09-03T04:20:54.317" Title="Am I required to obtain a student license before a sport, recreational, or private one?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19578" PostTypeId="1" AcceptedAnswerId="19580" CreationDate="2015-09-01T23:22:54.657" Score="5" ViewCount="1062" Body="&lt;p&gt;How long does training for student, sport, recreational, or private licenses &quot;count&quot; toward your license, before it's considered outdated/expired?  Can you start the process, intending to spread out the expense over something like 5 years, or in that situation, do you need to &quot;save up&quot; and do it all within a year or two?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question - My luck that I'm just starting to look into this, and there's a private pilot ground school course starting tomorrow nearby.  Is it premature for me to take this class, not having taken any other steps?  Would it be over my head, or would I need to take it again if I don't get the private license within a certain amount of time taking the class?&lt;/p&gt;&#xA;" OwnerUserId="10052" LastEditorUserId="62" LastEditDate="2015-09-03T02:09:46.747" LastActivityDate="2015-09-03T02:09:46.747" Title="Can I obtain a license over several years?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19579" PostTypeId="2" ParentId="19577" CreationDate="2015-09-01T23:33:08.287" Score="2" Body="&lt;p&gt;Yes. In order to get other type of licenses, you need to have a student pilot license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After getting a student pilot license, you can apply for a sport, recreational or a private license. For a commercial pilot license, you need a private pilot license (or should be a military or former military pilot with some conditions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These eligibility requirements can be found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2&quot; rel=&quot;nofollow&quot;&gt;Code of Federal Regulations Title 14 ID Part 61&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-01T23:33:08.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19580" PostTypeId="2" ParentId="19578" CreationDate="2015-09-01T23:48:06.777" Score="10" Body="&lt;p&gt;I'm assuming you're asking about the US, since you mentioned sport/recreational licenses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can take as long as you like to learn to fly, although spreading it out over multiple years will actually cost more, not less. The reason is that you forget things and take a lot longer to develop the right reactions, muscle memory and feel for the aircraft. So try to fly as much as possible and do your license as &lt;a href=&quot;https://aviation.stackexchange.com/q/14275/62&quot;&gt;quickly as possible&lt;/a&gt;, within whatever time and budget limits you have; I know that not everyone has the time and &lt;a href=&quot;https://aviation.stackexchange.com/q/627/62&quot;&gt;money&lt;/a&gt; to learn to fly in one month or even one year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for a ground school course, they're often planned to end with you taking the &lt;a href=&quot;https://www.faa.gov/pilots/become/knowledge/&quot; rel=&quot;nofollow noreferrer&quot;&gt;knowledge test&lt;/a&gt; required for private pilots and that test might even be included in the price. When you take the test it's valid for two years. If you don't pass your final checkride within those two years then you'll have to do the knowledge test again first. But that doesn't mean you have to do a ground school course again, you can work with an instructor and by yourself to refresh your knowledge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you're not sure about how/when to start training then the best thing you can do is talk to an &lt;a href=&quot;https://aviation.stackexchange.com/q/9869/62&quot;&gt;instructor&lt;/a&gt; about your situation and expectations. Any good flight school will be happy to have someone sit down with you and answer whatever questions you have. An &lt;a href=&quot;https://aviation.stackexchange.com/q/2045/62&quot;&gt;introductory flight&lt;/a&gt; would be a great way to start, if you haven't already done that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-09-01T23:48:06.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19582" PostTypeId="1" AcceptedAnswerId="19594" CreationDate="2015-09-02T00:53:38.020" Score="7" ViewCount="11658" Body="&lt;p&gt;I am having trouble understanding how this type of propeller generates thrust:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lHVHv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lHVHv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is so much different than a propeller on a Cessna and thrust would be provided differently. I am also confused of how the turbofan blades in a jet engine provide thrust: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dyESr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dyESr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doesn't the turbofan push the bypass air back really fast providing thrust?  How do each of the these propellers (turbo prop and turbofan) produce thrust?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="5517" LastEditDate="2015-09-02T15:47:03.440" LastActivityDate="2020-03-19T04:32:38.637" Title="How do the blades on a propeller generate thrust?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19583" PostTypeId="2" ParentId="19577" CreationDate="2015-09-02T01:51:01.157" Score="6" Body="&lt;p&gt;A student pilot certificate is just a medical certificate printed on yellow paper instead of white paper and with endorsement templates for soloing printed on the back.  Other than that presentation difference it is no different than the medical exam a certificated pilot takes for whatever class medical you apply for.  The fee for this varies by examiner and may set you back $75 or so, but that (and being able to pass a medical) is the only barrier to entry.  There is no flight training or knowledge requirement to get this certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you have a student pilot certificate / medical you have one of the requirements to solo and can train directly for any of the sport, recreational or private pilot certificates.  You'll want to focus on sport or private training, as pretty much no one pursues recreational certificates.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-02T01:51:01.157" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19584" PostTypeId="2" ParentId="19578" CreationDate="2015-09-02T02:03:16.287" Score="4" Body="&lt;p&gt;You can take as long as you want to train with the caveat that the longer you take the more money you will spend and the less progress you'll make for each hour of training undertaken.  Aside from all the minimum times, which you are sure to meet and exceed with an extended training schedule, they only time-based requirements when you take the checkride are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A knowledge test passing certificate dated within the preceding 24 calendar months (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=479d1cc6eef14d929e063c7f4b0bf6b4&amp;amp;mc=true&amp;amp;n=pt14.2.61&amp;amp;r=PART&amp;amp;ty=HTML#se14.2.61_139&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.39(a)(1)(i)&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;3 hours flight training with an instructor in the preceding 2 calendar months (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=479d1cc6eef14d929e063c7f4b0bf6b4&amp;amp;mc=true&amp;amp;node=sp14.2.61.e&amp;amp;rgn=div6#se14.2.61_1109&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.109(a)(4)&lt;/a&gt; for private pilot single engine)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It would be rare to not have at least 3 hours with an instructor before your checkride to do final training and a mock checkride, so this requirement should be easily met.  As long as you take your written test when you can envision taking your practical test within the next 2 years, you are fine to take your time training.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-09-02T02:09:51.787" LastActivityDate="2015-09-02T02:09:51.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19585" PostTypeId="2" ParentId="19576" CreationDate="2015-09-02T02:21:46.523" Score="2" Body="&lt;p&gt;There is a requirement to have the aircraft grounded to an approved grounding point in the hangar under certain conditions. This is for a number of reasons including the skin of the aircraft is the return path as we only use one wire in aircraft circuits and the return path is the aircraft skin itself. &#xA;Also the grounding points must be approved. When the tarmac or hangar is built the grounding bars or points are tested to make sure they are within specs. The resistance must be low enough to ensure they are the path of least resistance. &#xA;The first thing we do when an airplane enters the hangar is ground it. Every spot usually has its own grounding spot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are times that the airplane is not grounded, but typically for maintenance it is. Maintenance usually requires ground power to be applied to the airplane. Also when large aircraft and especially helicopters return from flight, they sometimes can have a large buildup of static electricity and this has caused some serious injuries in the past. This static electricity has to be dissipated and is done via a grounding wire to an approved grounding point.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AC21.99 Advisory Circular&#xA;  Electrical bonding of aircraft to earth has generally &#xA;  been aimed at protecting aircraft and personnel from the &#xA;  hazards associated with static electrical discharge. &#xA;  However, with utilisation of external power sources, &#xA;  electrical bonding to earth must also protect aircraft and &#xA;  personnel from the potential hazards associated with the &#xA;  electrical ground power supplies. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/rules/1998casr/021/021c99s2c14.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/rules/1998casr/021/021c99s2c14.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8774" LastEditorUserId="1467" LastEditDate="2019-07-09T08:18:38.433" LastActivityDate="2019-07-09T08:18:38.433" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="19586" PostTypeId="2" ParentId="19503" CreationDate="2015-09-02T02:32:13.963" Score="2" Body="&lt;p&gt;This is how it works and I am surprised you switched the altimeter, unless I am missing something in your question. The altimeter reads the barometric pressure and should be set before you go flying. The airport will report the elevation and the knob on the altimeter can be turned till the altimeter is set to the correct altitude. You can confirm there is no blockage and the altimeter works correctly by getting the barometric pressure for the airport from the control tower or weather station, and it should match the barometric pressure numbers in the corner of the altimeter. Pressure changes on a daily basis and must be set each time. When we do a B check before flight, this is the exact procedure we do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is more information needed to properly diagnose this problem. With the lack of information I will continue on a couple of assumptions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The altimeter has been bench tested and is serviceable&#xA;2) The altimeter system when installed in the plane does not match the local barometric pressure with the corresponding elevation&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was stated that the altimeter was replaced with a known good one. When this occurs the whole system must be pressure checked with a pitot-static test kit. This is a requirement since the system was opened up by replacing the altimeter. If this is not done the system is considered unserviceable. It appears this was not done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be complete I would check out the lowest point in the system for moisture and drain it if present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally the procedures including connecting the tester to the pitot static system and taping (covering) all ports not connected. Then pressure is applied to the system, simulating different elevations. The airplane altimeter should match the testers simulated elevation within a certain + or -, for all specified elevations. Additionally, the rate of change of elevation is monitored for any abnormalities that may indicate a problem with any internal mechanisms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the pitot-static tester is an absolute requirement in this situation.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastEditorUserId="8774" LastEditDate="2015-09-03T19:59:50.387" LastActivityDate="2015-09-03T19:59:50.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19587" PostTypeId="2" ParentId="19582" CreationDate="2015-09-02T02:38:27.023" Score="14" Body="&lt;p&gt;The picture of the turboprop is probably confusing you because you are looking at a shutdown engine.  For a multi-engine propeller airplane a desirable feature is that the propeller with auto-feather when shutdown, so that an in-flight engine failure will cause the prop to be in a minimal drag configuration.  This minimal lift, minimal drag configuration is what you posted, and this is not producing thrust.  When the engine is started and system pressure (oil, hydraulic, whatever controls the adjustable pitch prop for that particular engine) will drive the propellor pitch angle into lift-producing regimes.  Turboprops also typically feature &quot;Beta&quot; propellor pitch, which allows the propellor pitch to be adjustable past zero-lift into negative-lift and is used for landing rollout and (in some airplanes, perhaps not many) slowing down in-flight or steep descents.  During normal flight the turboprop propellor is producing lift just like the propeller on the cessna you are familiar with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The N1 fan in a turbofan (the big one you see when you look at the front of the engine) is a ducted fan.  The individual blades of the N1 fan are angled to push air backwards.  This works the same way as a big box fan you can buy at walmart.  The key difference is the N1 fan rotates an order of magnitude faster than a box fan.  The bypass air is accelerated by this fan and exits through the rear of the engine to produce thrust.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="511" LastEditDate="2015-09-02T15:07:35.373" LastActivityDate="2015-09-02T15:07:35.373" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19588" PostTypeId="1" CreationDate="2015-09-02T07:04:16.887" Score="4" ViewCount="348" Body="&lt;p&gt;What's holding equipment manufacturers from going into multicore, RTOS- based equipment?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recently, Rockwell Collins certified its display systems based on RTOS:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lynx Software Technologies, &lt;a href=&quot;http://www.lynx.com/lynxos-178-rtos-deployed-by-rockwell-collins-in-pro-line-fusion-series-of-flight-deck-systems/&quot; rel=&quot;nofollow noreferrer&quot;&gt;LynxOS-178 RTOS Deployed by Rockwell Collins in Pro Line Fusion Series of Flight Deck Systems&lt;/a&gt;, November 27, 2012.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why are major players not moving into these segments like RTOS, multicore processor? Is it because of certification difficulties?&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="15311" LastEditDate="2018-05-29T11:46:35.077" LastActivityDate="2018-05-29T11:46:35.077" Title="What's holding equipment manufacturers from going into multicore, RTOS-based equipment?" Tags="&lt;aircraft-systems&gt;&lt;avionics&gt;&lt;equipment&gt;&lt;software&gt;&lt;faa-approval&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="19589" PostTypeId="2" ParentId="19568" CreationDate="2015-09-02T07:43:02.437" Score="2" Body="&lt;p&gt;If you look up &quot;monocoque&quot;(external supported) structures, you will learn more about why the corrugated metal was used. It has extremely high &quot;shear&quot; strength. If you look at the PA-28 piper's horizontal stabilizer center panel with its corrugations, if that same piece were to be made of standard aluminum, it would bend if you pressed your hand from the top center to the bottom.&lt;/p&gt;&#xA;" OwnerUserId="10056" LastEditorUserId="1467" LastEditDate="2015-09-02T12:16:27.697" LastActivityDate="2015-09-02T12:16:27.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19590" PostTypeId="1" CreationDate="2015-09-02T07:56:09.417" Score="11" ViewCount="7867" Body="&lt;p&gt;Weird as it might seem, I'm not 100% sure what airplanes I can fly&#xA;with an EASA PPL(A) license. During the training the instructors would&#xA;tell me that I can fly airplanes up to 2000 kg MTOW and 5 passengers&#xA;or so, but I think they are wrong and this applies only to the (old)&#xA;national rules (Germany in this case).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The license states that I have a &lt;em&gt;SEP (land)&lt;/em&gt; class rating. I have&#xA;searched through the EASA rules (a cumbersome task on its own) and&#xA;nowhere could I find a weight or passenger limit, nor a specific&#xA;definition of what exactly qualifies as a SEP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, what aircraft am I entitled to fly with my PPL(A)&#xA;license? Do aircraft with specificities such as a retractable&#xA;gear fall into the same category? Please also point to the &lt;strong&gt;source&lt;/strong&gt;&#xA;of the applicable legislation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the same token, may I/may I not fly light aircraft such as e.g. a&#xA;K-10 Swift?&lt;/p&gt;&#xA;" OwnerUserId="9788" LastActivityDate="2020-01-19T20:37:42.343" Title="What airplanes can I fly with an EASA PPL license?" Tags="&lt;easa-regulations&gt;&lt;ppl&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19591" PostTypeId="2" ParentId="2359" CreationDate="2015-09-02T08:06:37.140" Score="1" Body="&lt;p&gt;While scrolling through the prices of aircrafts which cost’s more than the GDP of many countries, it seems logical to take aircrafts on lease rather than see one’s balance sheets drooping health. Well, this might not be the only reason why many airlines pick leasing options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By taking leased aircraft the airlines are able to maintain a fuel efficient and latest designs fleet, have better survival options at the time of geo – economic crises and traffic fluctuations. So this becomes a very company specific and situation specific decision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft leasing market is a very capital intensive business with high risks and higher returns. Since last few years this market is expanding –with Asia- Pacific region fuelling this growth. Asia-Pacific region is becoming the hub of emerging economies -China, Hong Kong, Japan to name some. Among these China is moving fast and is growing its fleet at a humongous rate. Boeing projected in its 2014 annual report that China will buy about six thousand aircraft worth 870 billion U.S. dollars by 2033.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multiple financing options, reduced lease and interest rates, bulk orders, growing Low Cost Carriers are all amplifying the growth of Global Aircraft Leasing Market&lt;/p&gt;&#xA;" OwnerUserId="10058" LastEditorUserId="3945" LastEditDate="2015-09-02T09:42:03.610" LastActivityDate="2015-09-02T09:42:03.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19592" PostTypeId="2" ParentId="19576" CreationDate="2015-09-02T09:41:14.657" Score="4" Body="&lt;p&gt;In general any aircraft parked in hangar should be electrically grounded. The grounding should be done from basic aircraft structure to a low resistance ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Grounding of the aircraft is usually done to,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Protect aircraft and personnel against hazards from lightning discharge.&lt;/li&gt;&#xA;&lt;li&gt;Provide current return paths&lt;/li&gt;&#xA;&lt;li&gt;Protect personnel from shock hazard&lt;/li&gt;&#xA;&lt;li&gt;Prevent accumulation of static charge&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;During de-fueling or refueling, the aircraft is grounded to the fuel truck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the aircraft are grounded to a point where the impedance is less than 10,000 ohms referenced to earth for &lt;em&gt;static&lt;/em&gt; grounding. For power grounding, it should be less than 10 ohms to power systems neutral.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are not grounded to the hangar structure as the external power supply, when connected, is grounded to that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best reference, if you ask me, would MIL- HDBK-274(AS)- Electrical Grounding for Aircraft Safety.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2016-03-12T01:05:26.453" LastActivityDate="2016-03-12T01:05:26.453" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19594" PostTypeId="2" ParentId="19582" CreationDate="2015-09-02T14:14:07.633" Score="14" Body="&lt;p&gt;The cross section of propeller blade is an airfoil. As the propeller rotates through the air, it generates lift, which becomes thrust as the it is directed forwards rather than vertically upwards as in aircraft wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m4D94.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m4D94.jpg&quot; alt=&quot;Propeller and airfoil forces&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: recreationalflying.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;relative airflow&lt;/em&gt; on the blade section (airfoil) is the resultant vector of two things - the forward motion of the propeller (the aircraft) and the rotational velocity of the propeller blade itself. Most of the propellers in use today are fixed speed variable pitch propellers. So, velocity experienced by the propeller blade is maximum at the tip (where the rotational speed is maximum) and minimum at the hub.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/059nH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/059nH.jpg&quot; alt=&quot;Propeller speed&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: americanflyers.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, at any RPM, different parts of the propeller are at different angles of attack. To remedy this, the airfoil sections are varied along the propeller. So the propeller is practically &lt;em&gt;twisted&lt;/em&gt; along its length, with the root at higher angle of attack. Also, in some cases, the airfoils are changed along the length (thinner ones are near tip).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xvfii.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xvfii.jpg&quot; alt=&quot;Airfoil sections along propeller&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.pilotfriend.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As already noted, the pitch of the propeller blades can be varied in flight. What the photo shows is a &lt;em&gt;feathered&lt;/em&gt; propeller i.e. a propeller that is set parallel to the airflow. This is done usually in order to reduce drag in case of engine failure. During normal operation, the blades will not be in feathered position. For example, in the figure below, the propeller of engine 1 feathered while the next one is not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BY3Z6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BY3Z6.jpg&quot; alt=&quot;A400 feathered propeller&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;From wikimedia commons, work by Julian Herzog&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aircraft, propeller pitch is changed with speed, with fine pitch at low speeds and strong acceleration (like takeoff) and a coarse pitch for high speed (cruise).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pFgKf.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pFgKf.gif&quot; alt=&quot;Propeller pitch settings&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:forum.warthunder.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most aircraft, the propeller pitch settings are adjusted automatically by a governor according to requirements. The following figure shows the pitch variation in flight for a similar propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MHXGR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MHXGR.jpg&quot; alt=&quot;ATR 72 propeller pitch variation&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Propeller_pitch_on_an_ATR_72.jpg#/media/File:Propeller_pitch_on_an_ATR_72.jpg&quot; rel=&quot;noreferrer&quot;&gt;Propeller pitch on an ATR 72&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Ariadacapo&quot; rel=&quot;noreferrer&quot; title=&quot;User:Ariadacapo&quot;&gt;Olivier Cleynen&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Thrust&lt;/strong&gt; The thrust in both turboprop and turbofan is provided by accelerating air through fans. In a turboprop, it the propeller, while it is the bypass fan in case of the turbofan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust produced, T is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T = \dot {m} * (v_{f} - v_{0})$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\dot{m}$ the mass flow rate of air and $v_{f}$ and $v_{0}$ are the final and initial (unaccelerated) velocities of the air respectively. Usually case of propellers, the mass flow rate $\dot {m}$ is higher, while in case of turbofans, the variation in velocity is comparatively higher.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-09-02T15:52:11.223" LastActivityDate="2015-09-02T15:52:11.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19595" PostTypeId="1" AcceptedAnswerId="19598" CreationDate="2015-09-02T15:43:33.100" Score="6" ViewCount="766" Body="&lt;p&gt;How much drag does a RAT deployment add? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was watching a simulator video of an A320 dual engine failure at low height during climb out and one step in the protocol was the pilot manually deploying the RAT. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/djd7f_azfiI&quot; rel=&quot;noreferrer&quot;&gt;Simulator Video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since he doesn't manage to make it back to the runway from his 2000 ft engine flameout run I was wondering if not deploying the RAT would make any difference due to reduced drag?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would the on-board batteries and windmilling engines be able to provide sufficient power for control surfaces?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, are there real life incidents of a 2000 ft (or lower) dual engine failure that made a safe return to the runway? Sully Sullenberger's A320 had reached approx. 3,000 ft, yet he was forced to ditch rather than return. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the energy management differ drastically from type to type? i.e. Among dual engined aircraft would some be easier to land from a 2000 ft dual engine failure than others? For typical climb profiles, weights etc. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-09-02T17:17:19.733" LastActivityDate="2015-09-02T19:07:40.717" Title="How much drag does a RAT deployment add?" Tags="&lt;engine-failure&gt;&lt;flight-simulator&gt;&lt;rat&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19596" PostTypeId="2" ParentId="19569" CreationDate="2015-09-02T17:03:50.053" Score="24" Body="&lt;p&gt;First, let's figure out how much power a 747 needs to takeoff:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine thrust = 284 kN&lt;/li&gt;&#xA;&lt;li&gt;Takeoff speed = 170 knots&lt;/li&gt;&#xA;&lt;li&gt;Takeoff power = 90% max power&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Using &lt;span class=&quot;math-container&quot;&gt;$P=Fv$&lt;/span&gt;, converting the variables to SI units, we get&#xA;&lt;span class=&quot;math-container&quot;&gt;$$Power=88,948,800 W$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, in other words, around &lt;span class=&quot;math-container&quot;&gt;$90MW$&lt;/span&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;EDIT: This calculation is only correct if the engine efficiency is 100%, because it is based on work done. For a realistic estimation, see &lt;a href=&quot;https://aviation.stackexchange.com/a/33711/3386&quot;&gt;Jan Hudec's answer&lt;/a&gt;. I'll leave the rest of this answer based on 90MW as I'm too lazy to update the numbers.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;But just &lt;strong&gt;&lt;em&gt;exactly how much is 90 megawatts&lt;/em&gt;&lt;/strong&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An average laptop computer consumes 20W on daily use. You can power &lt;strong&gt;4.44 million laptops&lt;/strong&gt; with this power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high-end desktop consumes 300W under heavy load. You can power &lt;strong&gt;300,000 desktop computers&lt;/strong&gt;. If you stack 20 of them in a server tower and put 100 towers on each floor, you need a data center with 150 floors to fit those machines in.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Let us take this a step further and evaluate the total energy needed for a flight. Assume all required energy comes from onboard energy storage (i.e. no solar panels / windmills). Let's also assume a full power climb to cruise altitude of 15 minutes, 50% power cruise for 4 hours, and a completely idle descent which does not consume any power at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using &lt;span class=&quot;math-container&quot;&gt;$E=\int P dt$&lt;/span&gt;, we get the total energy needed for a flight is &lt;span class=&quot;math-container&quot;&gt;$$720,485,280,000 J$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that amount of energy, you can pull a 735 kiloton object up 100m. If all those weights are water, that's close to &lt;strong&gt;300 Olympic swimming pools&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you power the whole plane with batteries, you'd need &lt;strong&gt;47 million AA batteries&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of course, if you manage to get 14 of these electrical 747s together, you can generate 1.21 gigawatts and get &lt;a href=&quot;https://www.youtube.com/watch?v=f-77xulkB_U&quot; rel=&quot;nofollow noreferrer&quot;&gt;Back to the Future&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2019-09-17T06:58:11.017" LastActivityDate="2019-09-17T06:58:11.017" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="19597" PostTypeId="1" AcceptedAnswerId="19599" CreationDate="2015-09-02T17:45:06.583" Score="14" ViewCount="23658" Body="&lt;p&gt;I'm a student pilot who has just begun dual cross-country with my instructor. However, he has not been explicit when I've asked him about radio comm with tower/approach/radio during the flight. If I enter an airspace (say, Class D) and contact the tower, but I do not intend to land there, what would my initial call to the tower be? And what are the differences in requests for approach/departure and tower? &lt;/p&gt;&#xA;" OwnerUserId="10066" LastEditorUserId="1696" LastEditDate="2015-09-02T19:50:16.807" LastActivityDate="2021-04-26T18:42:23.490" Title="What do I request when contacting tower of an airspace I'm transiting over?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;&lt;student-pilot&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19598" PostTypeId="2" ParentId="19595" CreationDate="2015-09-02T18:23:23.447" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Since he doesn't manage to make it back to the runway from his 2000 ft engine flameout run I was wondering if not deploying the RAT would make any difference due to reduced drag?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, because it deploys automatically. Note that in the video in the first attempt the step is not done because there is less time. It is probably included in the checklist just in case the automation didn't do it's job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, let's try to estimate the drag. All I could quickly find about the RAT is that the attached electric generator provides 5 kW, but that should be enough. We need to take into account the hydraulic pump and power losses, but the generator wouldn't be insignificant part of the load, so we could guess that the turbine does not have more than 50 kW of drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now potential energy is $E_p = mhg$, differentiating by time we get $P = v_{vert}mg$ and solving for vertical speed $v_{vert} = \frac{P}{mg}$. Taking some “median” weight of 60 t (A320 has MZFW 62.5 t and MLW 66 t) and substituting we get:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_{vert} = \frac{50\ \mathrm{kW}}{6\cdot10^4\ \mathrm{kg}\cdot 9.8\ \mathrm{ms}^{-2}} \approx 0.085\ \mathrm{ms}^{-1} \approx 17\ \mathrm{ft/min}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the deployed RAT increases the rate of descent by less than 20 ft/min.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the video mentions the best glide speed would be 205 knots (I suppose it is for the 1+F configuration; for clean it sounds too low, though I don't have a reference for this). Since the L/D ratio is around 18, that would give the total descent rate about:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_{vert} = \frac{205 \mathrm{knot}}{18} \approx 11 \mathrm{knot} \approx  1150 \mathrm{ft/min}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except, well, 18 is &lt;em&gt;clean&lt;/em&gt; L/D. The L/D at 1+F is a bit lower. I don't have reference for that either, but something like 10–12 sounds right, so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_{vert} = \frac{205 \mathrm{knot}}{12} \approx 17 \mathrm{knot} \approx  1730 \mathrm{ft/min}$$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is about 100 times more. So the RAT might increase drag by 1%. It was very rough estimate, so it may be 2% or 0.5%, but it definitely isn't that significant.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Would the on-board batteries and windmilling engines be able to provide sufficient power for control surfaces?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The training manual mentions that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If engine wind milling is sufficient, additional hydraulic power may be recovered.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;without saying at what speeds that would be, but generally the speed for wind milling engine restart are significantly higher that the best glide speed. I'd say the necessary speed would be more than 250 knots.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, are there real life incidents of a 2000 ft (or lower) dual engine failure that made a safe return to the runway? Sully Sullenberger's A320 had reached approx. 3,000 ft, yet he was forced to ditch rather than return.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can't find &lt;em&gt;any&lt;/em&gt; other incidents involving dual engine failure on A320-family aircraft besides US Airways 1549. And I am not aware of any incidents on any other aircraft that would fit that criteria either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should however be noted, that flight 1549 likely had enough altitude to return to the runway—if the manoeuvre was executed perfectly. A small mistake and they'd crash into populated area since the airport is in the middle of a city. &lt;em&gt;The&lt;/em&gt; Sullenberger's great airmanship was in that he chose the worse option that he was certain he can make over the better option where he was not.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does the energy management differ drastically from type to type? i.e. Among dual engined aircraft would some be easier to land from a 2000 ft dual engine failure than others?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Principally it's the same for any type. But since turn radius increases drastically with speed, slower aircraft can turn faster and thus could return from lower altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a related question that discusses the manoeuvre; and it's dangers: &lt;a href=&quot;https://aviation.stackexchange.com/questions/786/is-it-even-remotely-feasible-to-turnback-a-single-engine-aircraft-with-an-engine&quot;&gt;Is it even remotely feasible to turnback a single engine aircraft with an engine failure?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-09-02T19:07:40.717" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19599" PostTypeId="2" ParentId="19597" CreationDate="2015-09-02T18:25:44.157" Score="9" Body="&lt;p&gt;It's the standard initial contact: who you are talking to, who you are, where you are, what you want.  &quot;Madison Approach, Cessna 123AB, 15 miles south at 3000 feet, request to transition your airspace to the north.&quot;  If it's class B, C, or a TRSA your call will be to Approach and they will give you a squawk code and the local altimeter.  For class D, there is no approach so call the tower with the same request.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2015-09-02T18:25:44.157" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19601" PostTypeId="2" ParentId="19597" CreationDate="2015-09-02T18:57:11.197" Score="13" Body="&lt;p&gt;This will vary for every airspace so lets go over them in descending order.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Class B (Bravo):&lt;/strong&gt; First off, keep in mind for your future solos that as a student pilot you are not allowed to fly solo in class B airspace unless your instructor has given you training and a logbook endorsement for that specific class B (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_195&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.95&lt;/a&gt;). But if your instructor is in the plane then technically they are accepting the clearance, not you. For Bravo airspace a clearance is explicitly required and a typical exchange will go something like this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;PIC: &amp;quot;1234XY 5 miles south west of KPHL at 4000 heading to KPNE requesting transition through the airspace.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;ATC: &amp;quot;1234XY squak 3425 and ident, altimeter 29.92&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;PIC: &amp;quot;1234xy 3425 29.92&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;ATC: &amp;quot;Ident received, you are cleared through to KPNE on your current heading at 4000&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;En route you may get traffic advisories or other instructions while in the space so you need to stay on the frequency.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Class C (Charlie):&lt;/strong&gt; For Charlie airspace you only need to establish 2-way radio communication. A response containing your call sign will allow you into the space. Lets look at an example&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;PIC: &amp;quot;Allentown approach 1234XY 20 miles to the southeast of Queen City at 3000 in bound for landing at Queen City&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;ATC: &amp;quot;1234XY standby&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Anytime you hear your call sign, it is considered to be the establishment of 2-way radio communication, if you hear &amp;quot;aircraft calling Allentown, standby&amp;quot;, you have not established 2-way communication and must remain out of the space since they did not respond with your call sign. Likewise you may be explicitly instructed that you must remain out of the space.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Class D (Delta):&lt;/strong&gt; Delta airspace typically  extends up to 2500AGL, and you can often climb over it flying VFR. You do not need to hail the tower when doing so but many people do so out of courtesy. If you intend to enter Class D, follow the same procedure as Class C.&lt;/p&gt;&#xA;&lt;p&gt;You can find the &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=42&amp;amp;sID=505&amp;amp;preview=true&quot; rel=&quot;nofollow noreferrer&quot;&gt;whole breakdown here&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Flight Following:&lt;/strong&gt; Where available and workload permitting you may be able to pick up flight following while in route. You can also coordinate a hand off from them to the airspace you are entering.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-03T17:42:05.743" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19603" PostTypeId="2" ParentId="19597" CreationDate="2015-09-02T19:06:09.367" Score="8" Body="&lt;p&gt;First, you should contact the tower &lt;em&gt;before&lt;/em&gt; you enter their airspace. Class B (around big international airports) requires explicit clearance to enter, while C/D airspaces around smaller commercial, military and GA airfields require two-way communication with the controller prior to entry (clearance is implied if not expressly denied; you'll hear &quot;remain outside&quot; or &quot;remain clear&quot; if you shouldn't enter).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To initiate communication for any purpose, you usually start by saying the name of the ATC station you are calling, including the type of controller you need to talk to. Let's assume you're flying into Franklin Regional Airport (no clue whether such an airport exists or where it is, just an example). Most Delta towers have a single team of controllers handling every aspect of traffic control, and &quot;Franklin Tower&quot; will suffice. Depending on the airport, they may prefer you use more phase-specific controller names like &quot;ground&quot; (for taxi instructions), &quot;tower&quot; (for takeoff/landing clearance), &quot;departure&quot; (for routing from the runway to the edge of their airspace) or &quot;approach&quot; (for any initial contact where you start outside and want to come in), even if the same small team of controllers in or near the control tower handle all of these things. Since you want to transit, &quot;Franklin Approach&quot; is normally also acceptable. To be friendly (they are human after all) and also to indicate this is an initial transmission with a callsign they don't know about yet, you can start with a salutation, but it's optional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You then immediately follow this with your callsign (usually the make and tail number of your aircraft, for instance &quot;Piper 342 Lima&quot;), followed by your approximate range and compass radial from the facility, and then your flight mode (VFR, IFR, VFR-On-Top), and finally what you want (in this case to transit their airspace).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, your initial transmission would go something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Good afternoon Franklin Approach, Piper Three Four Two Lima, five miles northwest, VFR, request transit to the southwest.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The response you'll get depends on several things. Usually, you will hear something along these lines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper Three Four Two Lima, squawk 2451 and read altimeter tape.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is their acknowledgement that you wish to enter and pass through their space, and for you to do so, they need to be able to identify you on their radar using your transponder, and know what your indicated altitude is (your Mode C transponder will tell them the same, but not all aircraft have Mode C reporting and it can take a few seconds for their display to update). You comply by setting your transponder and replying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper Three Four Two Lima squawking 2451, altitude two thousand five hundred.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The tower's next move will usually then be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper Three Four Two Lima, radar contact, proceed on course.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They are telling you that they can now identify your plane on their screens, and that you are clear to continue flying along your present course at your current altitude. They can, since they control the airspace, instruct you to turn to a different heading, or to climb or descend to a different altitude, in order to accommodate the normal traffic pattern or to route you around another transiting aircraft. If you need to turn, climb or descend without being instructed by the tower, it's usually good to request a heading or altitude change so the tower can make sure you're still going to stay clear of other traffic they control, especially IFR flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tower can respond in other ways to your initial transmission. A critical distinction is that the controller &lt;em&gt;must&lt;/em&gt; respond using your callsign in order for two-way communication to be established. If they respond to your transmission in any other way, communications are &lt;em&gt;not&lt;/em&gt; established, and therefore you &lt;em&gt;cannot&lt;/em&gt; enter their airspace. A common reason they wouldn't acknowledge you by callsign is that your transmission got garbled by other radio traffic or noise interference:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft calling Franklin Tower, say again.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;... or you don't have your mike plugged in:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft calling, carrier only no modulation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;... or they're too busy to deal with you:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft calling Franklin Tower, standby.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also keep in mind that if they heard you loud and clear and respond to you by callsign, they can still keep you out:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper Three Four Two Lima, remain clear, expect further instruction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even though two-way comms are established, you cannot enter their airspace if they tell you to keep out. If you hear this, their airspace is likely too full to accomodate an additional plane, even transiting. In such a case, if you can get where you're going without crossing their airspace, it's probably a good idea:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper Three Four Two Lima copies, cancel request, we will fly around your Delta.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you can and wish to terminate communications with the tower at this point (since you're going to stay outside their airspace there's not much reason to keep talking to them), you can indicate this by ending your transmission with your callsign instead of beginning with it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Copy Franklin Tower, cancel request, we will fly around your Delta, good day Piper Three Four Two Lima.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The tower then knows you have likely switched off their frequency and will not respond to further transmissions. If they need to contact you again, they'll likely try on the surrounding MULTICOM or UNICOM frequency, or on GUARD, but as long as you stay outside their airspace there would be little reason for them to try.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2018-11-13T19:55:22.123" LastActivityDate="2018-11-13T19:55:22.123" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19604" PostTypeId="1" AcceptedAnswerId="19611" CreationDate="2015-09-02T19:56:35.840" Score="6" ViewCount="7415" Body="&lt;p&gt;Reading the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow&quot;&gt;Wikipedia page&lt;/a&gt;, I see that the F-16 began production in 1973. That seems pretty old to me. So I ask, why is the F-16 still in service in many countries around the world? Is it that a superior fighter has been not been designed yet, or are there other reasons?&lt;/p&gt;&#xA;" OwnerUserId="10068" LastEditorUserId="1696" LastEditDate="2018-04-13T16:25:27.267" LastActivityDate="2018-04-13T16:25:27.267" Title="Why is the F-16 still in service?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;f-16&gt;" AnswerCount="6" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19605" PostTypeId="2" ParentId="19604" CreationDate="2015-09-02T20:41:06.473" Score="7" Body="&lt;p&gt;It fulfills the role it was designed for adequately, a replacement is not needed so why would they stop using it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot;&gt;B-52 Stratofortress&lt;/a&gt; was introduced in the 1950s and is still in service.&lt;br&gt;&#xA;The airframes are older than their flight crews and have undergone extensive refits over the decades, but the basic design is 60 years old.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-02T20:41:06.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19606" PostTypeId="1" AcceptedAnswerId="19608" CreationDate="2015-09-02T20:47:23.550" Score="5" ViewCount="1142" Body="&lt;p&gt;During flight from one country to another, can I use my hand held radio during flight to listen to ATC?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastActivityDate="2015-09-02T22:15:50.150" Title="As a passenger, can I use my handheld radio in commercial flights?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19607" PostTypeId="2" ParentId="19604" CreationDate="2015-09-02T20:47:50.770" Score="6" Body="&lt;p&gt;The F-16, is a fairly cheap fighter to buy and to operate. Despite its age, it is still a very capable fighter if fitted with the right systems. It is not suitable for every theater. It depends on the level of sophistication of the enemies weapons. If they are too modern, it's better to have a different fighter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not every country is able to afford more expensive fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recently read that in a one to one dogfight between an F-16 and the new F-35, the F-16 is still the master. &lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-09-02T20:47:50.770" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19608" PostTypeId="2" ParentId="19606" CreationDate="2015-09-02T20:49:26.343" Score="2" Body="&lt;p&gt;This actually varies from country to country. You can use it in the US (but I cant promise people wont look at you funny). In the UK its actually illegal to do so you can see a full discussion &lt;a href=&quot;https://aviation.stackexchange.com/questions/3264/is-it-illegal-for-joe-public-to-listen-to-atc-in-the-uk&quot;&gt;here on that topic&lt;/a&gt;. If you intend on doing this I would advise checking the local laws on what you can and cant do.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-09-02T20:49:26.343" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19609" PostTypeId="1" CreationDate="2015-09-02T21:17:30.313" Score="12" ViewCount="2412" Body="&lt;p&gt;Occasionally I come across the diesel-electric (DE) design for submarines and freight trains. They say something like &quot;a diesel engine powering an electric drive lets the two operate at their most efficient RPMs, and the electric drive has very little losses in efficiency.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question hit me: Has there even been a DE helicopter? Is there something about the DE system that makes it bad for the aviation industry? Weight maybe? But note we do not need a bunch of batteries like on a submarine. We don't need to store the power, we just convert it to electricity which goes immediately into the electric drive for the rotors.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2019-02-23T04:10:42.563" Title="Has there ever been a diesel-electric helicopter?" Tags="&lt;aircraft-design&gt;&lt;helicopter&gt;&lt;aviation-history&gt;&lt;engine&gt;" AnswerCount="5" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19611" PostTypeId="2" ParentId="19604" CreationDate="2015-09-02T22:05:08.043" Score="24" Body="&lt;p&gt;The simplest answer to your question is that the F-16 has not yet been retired because, for its cost, there's nothing better being built in enough numbers to replace the nearly 4500 Falcons produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16 was designed on the trailing edge of a surge in technological development by the U.S. military in the wake of Vietnam. The U.S. had fought that war with an air force primarily designed for a standoff engagement with the Soviet Union directly, thus emphasizing interceptor-style fighters targeting bombers at extreme range using missiles. Robert McNamara, U.S. SecDef for the Johnson and Nixon administrations, also emphasized a &quot;one-size-fits-all&quot; approach to aircraft design, requiring the USAF and Navy to collaborate on common aircraft designs that covered a multitude of mission profiles. This created the F-4, a fast but heavy plane that was a handful to fly, weaknesses that were exploited by pilots of technologically-inferior MiG-19 and MiG-21 aircraft in close combat engagements that the Phantom was ill-prepared to fight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lesson &quot;dogfighting isn't dead&quot; prompted a renaissance in jet fighter design in the 70s, producing the F-14 and F-15 long-range air superiority fighters, and the smaller F-16 and F/A-18 multirole fighters. Maneuverability, a wide range of weapons from guns to long-range missiles, and high pilot situational awareness by reducing workload and integrating flight and fire control systems, were all emphasized strongly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Soviets were taken somewhat by surprise at this surge; as of when the F-16 first flew, the Soviet air force and those of its allies had nothing that could compete. They answered a few years later with the MiG-29, a smaller twin-engine design similar to the larger Su-27 which was in pre-production to answer the F-15. These six fighters - F-14, F-15, F-16, F/A-18, MiG-29 and Su-27 - represented the cutting edge of fighter design as of the collapse of the Soviet Union in 1991. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new U.S. designs to enter production since, the F-22 Raptor and F-35 Lightning II, are themselves fairly old; the first production F-22 was built in in 1996 and flew in 1997, almost 20 years ago, the result of a design competition with planes flying back in 1990, and the initial RFP originating in the 1980s. The F-35 first flew in 2006, itself derived from the X-35 JSF testbed which first flew in 2000, so that design is between 10 and 15 years old now depending on how you count. Their protracted development times are a direct result of the reduction in pace of the U.S.-Russian arms race since 1991; with no other technologically-advanced military adversary on the horizon, there simply hasn't been the impetus to get these planes out to the front lines (there is some civilian talk of restarting the F-22 production line to bolster Raptor numbers, as the Sukhoi PAK-FA and Chengdu J-20 are very close to production and the F-35 is way behind projections and proving a disappointment so far, but another 100 new Raptors are projected to cost a ludicrous $225 million each due to increased costs of restarting the line and producing them in parallel with the F-35).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35 also had the handicap of being a return to the &quot;one-size-fits-all&quot; design mentality, being intended as a replacement for practically everything besides the Raptor in the U.S. air arsenal, Air Force, Navy and Marines, with an F or A in its designation. That's caused a lot of technological headaches, since any replacement for the Marines' AV-8B Harrier is going to need STOVL capability, and the Navy and Air Force have always had a different though overlapping set of requirements relating to the Navy's basic need to operate aircraft from a ship at sea that's maybe a fifth as long as the USAF's &lt;em&gt;minimum&lt;/em&gt; runway length requirements for its airbases. The resulting design is big, heavy, and relies on the most powerful single engine the U.S. has ever put in a fighter, which pushes the boundaries of the stress limits of the materials we use to make jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, military spending in the last 10 years or so has been preoccupied with developing and fielding technology to fight a low-tech insurgency; our enemies know they can't beat us in a toe-to-toe fight, so they don't fight that way, instead targeting our multi-million-dollar military hardware with Vietnam-era milsurp RPGs and oil-drum IEDs costing maybe $100 a shot. On this kind of battlefield, stealth air-superiority aircraft are kind of redundant as the enemy doesn't even have radar, much less an air force to exercise superiority over. That's why the F-22 has never seen real combat; the U.S. has enjoyed &quot;air supremacy&quot; by default in its primary combat theaters, as its enemies have never fielded an air force to speak of.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2016-04-05T15:58:18.623" LastActivityDate="2016-04-05T15:58:18.623" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19612" PostTypeId="1" AcceptedAnswerId="19617" CreationDate="2015-09-02T22:13:11.257" Score="-3" ViewCount="6067" Body="&lt;p&gt;I was reading a article &lt;a href=&quot;http://www.brookings.edu/blogs/techtank/posts/2015/08/06-engine-design-fuel-costs&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link &lt;/a&gt;It stated that lower bypass ratio jet engines have higher thrust than high bypass ratio engines, but the boeing 707 has 4 of these low bypass ratio engines and only travels about 600mph. Most modern high bypass ratio engines travel at about 514mph(push boeing 737-800 aircraft at an average of this speed) and only have 2 of these high bypass ratio engines &lt;a href=&quot;https://i.stack.imgur.com/zGJiv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zGJiv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; Boeing 737-800 engine.I am having trouble understanding how this works. &lt;a href=&quot;https://i.stack.imgur.com/RO4LB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RO4LB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="22726" LastEditDate="2018-05-25T18:28:41.377" LastActivityDate="2018-05-25T18:28:41.377" Title="How does a boeing 707 have 4 engines instead of 2?" Tags="&lt;jet-engine&gt;&lt;airliner&gt;&lt;boeing-707&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ClosedDate="2015-09-03T02:22:01.897" ContentLicense="CC BY-SA 3.0" />
  <row Id="19613" PostTypeId="2" ParentId="19606" CreationDate="2015-09-02T22:15:50.150" Score="3" Body="&lt;p&gt;I don't know if you are &quot;authorized&quot; to... but I can tell you that it likely won't work.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've tried a &lt;a href=&quot;https://www.sportys.com/pilotshop/sporty-s-sp-400-handheld-nav-com-aviation-radio.html&quot; rel=&quot;nofollow&quot;&gt;handheld aviation radio&lt;/a&gt; in a commercial cabin, and was unable to hear the ATC side of transmissions at all.  This was likely due to having a very short antenna inside a large metal cylinder, a long way from the source of the transmission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was nearly impossible to follow the communications when I could only hear my flight crew's side of the conversation.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-09-02T22:15:50.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19615" PostTypeId="1" AcceptedAnswerId="72242" CreationDate="2015-09-02T23:23:55.583" Score="8" ViewCount="1058" Body="&lt;p&gt;Takeoff and landing efficiency at an airport seems to depend on a number of factors, like number of runways and gates, infrastructure maintenance, weather, or even notorious traffic congestion in some areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mQM3Q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mQM3Q.jpg&quot; alt=&quot;Busy approach at Heathrow&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Busy approach at Heathrow, &lt;a href=&quot;https://www.youtube.com/watch?v=pw5Om1zLBIA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Youtube&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some process to prevent airlines to schedule more flights than the destination airport capacity? e.g. some coordination between ATC, airlines, and airports management. If so, how are airlines requests handled, is there some rule for fair sharing of the most demanded time slots?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-12-04T00:56:05.913" LastActivityDate="2019-12-04T16:37:24.217" Title="Can airlines schedule more flight arrivals than the destination airport capacity?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;flight-schedules&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="19616" PostTypeId="2" ParentId="19615" CreationDate="2015-09-03T00:01:24.240" Score="5" Body="&lt;p&gt;I'll answer for the US. As long as there's no official slot program, airlines can schedule however much they want to an airport, beyond what it should be capable of handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that doesn't mean ATC lets a free-for all happen. Hopefully, various traffic management units are on it and aware of how much demand is scheduled and already airborne into the airport/region/area that there's too much demand, and will implement various flow control programs to moderate the volume to what can be accepted into a specific sector(Certain airways can get super busy and require these types of actions), or airport. These control programs will either slow aircraft farther out from their destination, hold, or give small to longer delays on the ground, depending on how over scheduled or limitations of weather at the destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Begin edit poriton]&#xA;Since the other part of the question wasn't there when I first answered, I'll answer now.&#xA;Slot controls vary heavily from airport to airport. In the US, LGA, LGB, DCA, SNA, and at times JFK are slot controlled, with a few others threatened to go to slots due to how many delays they impact the system(SFO, EWR, and ORD). How each airport deals with the slot allocation is different due to how they got slot controls. DCA is controlled partly through congress, LGA and SNA are restricted due to noise controls. In the US, once an airline gets a slot, often times it's considered transferable property, so airlines can sell them to each other if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if a slot isn't used and goes back to the airport, the airport can put it up for bid, or allow applications for it, again depending on how their program is structured. AT DCA, some slots are transferable, some require an act of congress to change or modify, and some can only be used for certain routes or types of cities.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="3386" LastEditDate="2017-01-16T10:02:56.723" LastActivityDate="2017-01-16T10:02:56.723" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19617" PostTypeId="2" ParentId="19612" CreationDate="2015-09-03T00:03:56.680" Score="4" Body="&lt;p&gt;Boeing 707 was initially designed to use the P&amp;amp;W JT3C &lt;em&gt;turbojet&lt;/em&gt; engine.&#xA;Early versions of the '707 (like the one in the first picture of your question) and C-135 (including KC-135A) used those engines.&#xA;Wikipedia reports a &lt;strong&gt;maximum thrust&lt;/strong&gt; of &lt;strong&gt;12,030 lbf&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The JT-3D is one of the firsts &lt;em&gt;early low-bypass ratio turbofans&lt;/em&gt; (1958/59). It's based on the JT3c and, according to &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT3D#Specifications_.28JT3D-1.29&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, has a &lt;strong&gt;bypass ratio&lt;/strong&gt; of &lt;strong&gt;1.42:1&lt;/strong&gt; and a &lt;strong&gt;maximum thrust&lt;/strong&gt; of about &lt;strong&gt;17,000 lbf&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CFM-56 first run was in 1974, more than 15 years later. The CFM-56 is a &lt;em&gt;high-bypass ratio turbofan&lt;/em&gt;, with a &lt;strong&gt;bypass ratio&lt;/strong&gt; of &lt;strong&gt;5.5:1&lt;/strong&gt; and a &lt;strong&gt;maximum thrust&lt;/strong&gt; of &lt;strong&gt;19,500 lbf&lt;/strong&gt; for the CFM56-7B18 model that powers the Boeing 737-600 as reported on &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56#Specifications_.28CFM56-7B18.29&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer to your question is that at the time the Boeing 707 was designed, the only available engines were turbojets with a limited (for today standards) thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article you're asking about refers to &lt;em&gt;modern&lt;/em&gt; jet engines. Today low-bypass ratio turbofans are used mainly in military supersonic aircrafts, were fuel efficiency is less important than thrust and supersonic efficiency.&#xA;The opposite applies on modern civil aircrafts.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="9656" LastEditDate="2015-09-03T00:13:38.463" LastActivityDate="2015-09-03T00:13:38.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19619" PostTypeId="1" CreationDate="2015-09-03T01:05:41.143" Score="1" ViewCount="207" Body="&lt;p&gt;If a large jet aircraft is holding short of runway 28L while I am landing a single-engine aircraft on runway 28R, how should I proceed with such a landing?&lt;/p&gt;&#xA;" OwnerUserId="10069" LastEditorUserId="19" LastEditDate="2017-01-25T10:36:04.543" LastActivityDate="2017-01-25T10:36:04.543" Title="How should wake turbulence from aircraft on the ground be avoided during landing?" Tags="&lt;general-aviation&gt;&lt;student-pilot&gt;&lt;cessna-172&gt;&lt;wake-turbulence&gt;&lt;cessna-152&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19620" PostTypeId="1" AcceptedAnswerId="19630" CreationDate="2015-09-03T01:26:52.290" Score="4" ViewCount="1392" Body="&lt;p&gt;I have been understanding more about engines lately, but I can't figure out what the section in the middle of a turbofan is for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nIzxCm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nIzxCm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What benefit does this part provide to rotating the air? Is it some kind of separate fan or something?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="39" LastEditDate="2015-09-03T02:36:36.830" LastActivityDate="2015-09-03T06:18:50.623" Title="What is the thing in the middle of the turbofan?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19621" PostTypeId="2" ParentId="19619" CreationDate="2015-09-03T01:31:18.207" Score="10" Body="&lt;p&gt;Wake turbulnce occurs when an aircraft is creating lift.  Since, the airliner is on the ground, there is no wake turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are worried about jet blast from the airliner holding short between the runways, then I would land past the airliner by about 1000 ft.  With the airliners engines at idle, there will be minimal jet blast but if the increase power that jet blast increases significantly.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="3386" LastEditDate="2015-09-03T04:23:14.143" LastActivityDate="2015-09-03T04:23:14.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19623" PostTypeId="1" AcceptedAnswerId="19628" CreationDate="2015-09-03T02:10:42.397" Score="-5" ViewCount="832" Body="&lt;p&gt;I was reading something about jet engines and it stated that the exhaust comes out of the exhaust nozzle at about 1,300mph, and it also said that the compressors help reduce the speed of the air flowing into the core, so is this true? &lt;a href=&quot;http://www.explainthatstuff.com/jetengine.html&quot; rel=&quot;nofollow&quot;&gt;Link for the website it is on&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-03T06:42:16.420" Title="If you removed the compressors in an airlines engine would it have more thrust?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-09-03T10:06:27.057" ContentLicense="CC BY-SA 3.0" />
  <row Id="19624" PostTypeId="2" ParentId="19612" CreationDate="2015-09-03T02:12:41.807" Score="2" Body="&lt;p&gt;Engine technology has improved tremendously since the days of the Boeing 707. Today's engines are larger, more powerful, more efficient and quieter than their predecessors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines used in first production Boeing 707s (from 1958), the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney JT3C&lt;/a&gt; &lt;em&gt;turbojet&lt;/em&gt;, developed a thrust of 50KN (11200 lbf). This engine was the first one (in US) to develop more that 10000 lbf. The same engine (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney J57&lt;/a&gt;) was used in the B-52B stratofortress. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This engine was selected as it was the best available (in fact, the J57 designers won the &lt;a href=&quot;https://en.wikipedia.org/wiki/Collier_Trophy&quot; rel=&quot;nofollow noreferrer&quot;&gt;Collier trophy&lt;/a&gt; for their efforts). In fact, the engine was so successful that aircrafts were designed around it- half of the century series USAF fighters used them, as did 707's competitor, the Douglas DC-8. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for Boeing 737, which had its first flight around 10 years later, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT8D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney JT8D&lt;/a&gt; used was a low bypass &lt;em&gt;turbofan&lt;/em&gt; engine, having a bypass ratio of 0.96:1. Again, it was developed from a military engine, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J52&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney J52&lt;/a&gt; (which powers Northrop Grumman EA-6B Prowler, among others). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One pattern we can see clearly is that most of the early civil aircraft engines were developed from military turbojets. The reason was that only these powerplants could generate the required thrust at that time and today's high bypass turbofans were not even in the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as the airliners became fuel conscious and noise became a major issue, high bypass turbofans were developed exclusively for civil use and the development of civil and military engines diverged. With time, the bypass ratios have increases with decreases in fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WLCu7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WLCu7.jpg&quot; alt=&quot;Bypass ratio increase&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: compositesworld.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a comparison, the Rolls Royce Trent-1000 engines used in Boeing 787 can generate 350KN (78000 lbf) of thrust, more than 6 times that of JT3C. So, for meeting the thrust requirement of the four engined Boeing 707, you don't even need a single 787 engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the context, it is more useful if you compare the engines used in the same aircraft over the years. The most powerful engine used in the 707, the Pratt &amp;amp; Whitney JT3D-7 increased thrust over JT3C by over 50%. In case of 737, the 737 MAX uses &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_LEAP&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM International LEAP&lt;/a&gt;, which doubles the thrust on the PW JT8D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the article, what I get is this: For a given power available to the bypass fan, it can be used in either the two ways- take less air and increase the pressure of it more or take more air and have a lesser increase in pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the military turbofans have a lower bypass and higher thrust to weight ratio. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_F119&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney F119&lt;/a&gt; used in F-22 Raptor has a bypass ratio of 0.3:1 and a thrust to weight ratio in excess of 9, while the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;nofollow noreferrer&quot;&gt;General Electric GenEx&lt;/a&gt; used in Boeing 787 has a bypass ratio of 9.6:1 and a thrust to weight ratio of 5. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-03T02:12:41.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19625" PostTypeId="2" ParentId="19620" CreationDate="2015-09-03T02:31:34.427" Score="6" Body="&lt;p&gt;That's called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Spinner_(aeronautics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;spinner&lt;/a&gt;, and it's not that weird! You see them on propellers and turbofans alike. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinners are a streamlined shape, and provide aerodynamic drag reduction to what would otherwise be a very draggy, complex part of the powerplant. Here's how a propeller looks underneath:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Propeller_(aeronautics)#/media/File:Propeller_diagram.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dCMIzm.jpg&quot; alt=&quot;Cutaway of controllable pitch prop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps that can explain why streamlining the middle of a propeller (whether a turbofan disc or not) might be beneficial to performance. PeterKämpf would better be able to address the aerodynamics, but I am under the impression that cleaning up the airflow at the center of the propeller or fan improves efficiency of the blades as they are encountering less turbulent airflow.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-09-03T02:37:09.030" LastActivityDate="2015-09-03T02:37:09.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19626" PostTypeId="2" ParentId="19623" CreationDate="2015-09-03T02:46:44.493" Score="1" Body="&lt;p&gt;If you remove the compressor stages entirely, you no longer have an engine.  You will have a combustion flamefront that expands in both directions and will not provide enough flow to power the turbines.  Lack of cooling flow provided by normal airflow will result in the metals in the engine core melting and likely damage the engine beyond repair.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, removing the compressor yields an expensive paperweight that turns into scrap metal if you ever turn it on.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-03T02:46:44.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19628" PostTypeId="2" ParentId="19623" CreationDate="2015-09-03T03:56:55.917" Score="4" Body="&lt;p&gt;In case of jet engines, compressor increases the pressure of the incoming air, which carries out two functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pressurised air aids in the combustion with increased effeciency. If the air is not compressed, especially at high altitudes, the combustion process will grind to a stop.&lt;/li&gt;&#xA;&lt;li&gt;If there is no compressor, and by by some miracle combustion happens in combustion chamber, the low pressure in front means that the flame will exit in all the directions. This will stop the turbine.&lt;/li&gt;&#xA;&lt;li&gt;If the compressor is not there, the engine cooling will not be there and combustion chamber and possibly the turbine blades will melt.&lt;/li&gt;&#xA;&lt;li&gt;If the compressor doesn't reduce the air velocity, combustion process will become extremely difficult, the problem faced in scramjet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, if there is no compressor, there will not be an engine as we know it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest engine comes to having no compressor is during a &lt;a href=&quot;https://en.wikipedia.org/wiki/Compressor_stall&quot; rel=&quot;nofollow noreferrer&quot;&gt;compressor stall&lt;/a&gt;, when all the above things happen- the engine flames out and loses thrust while flames exit all over the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cdvUi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cdvUi.jpg&quot; alt=&quot;C-17 engine compressor stall&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, the engine is damaged beyond economical repair.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a type of engine without compressor- the &lt;em&gt;Ramjet&lt;/em&gt; engine. However, even here, the incoming air is compressed by the inlet. This engine has no turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qybJt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qybJt.png&quot; alt=&quot;Ramjet Engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Ramjet_operation.svg#/media/File:Ramjet_operation.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ramjet operation&lt;/a&gt;&quot; by Vector image made by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Cryonic07&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Cryonic07&quot;&gt;Cryonic07&lt;/a&gt;. Sourcepng-drawing was made by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Emoscopes&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Emoscopes&quot;&gt;Emoscopes&lt;/a&gt; and later slighlymodified by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Wolfkeeper&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Wolfkeeper&quot;&gt;Wolfkeeper&lt;/a&gt; - Based on &lt;a href=&quot;//commons.wikimedia.org/wiki/File:Ramjet_operation.png&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;File:Ramjet operation.png&quot;&gt;Image:Ramjet operation.png&lt;/a&gt;&lt;a href=&quot;//commons.wikimedia.org/wiki/File:Inkscape_to_text.svg&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;File:Inkscape to text.svg&quot;&gt;&lt;/a&gt;This vector image was created with &lt;a href=&quot;//commons.wikimedia.org/wiki/Help:Inkscape&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Help:Inkscape&quot;&gt;Inkscape&lt;/a&gt;, and&amp;nbsp;then&amp;nbsp;manually&amp;nbsp;edited.. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the ramjet engine cannot start by itself and can operate only at supersonic speeds. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-03T03:56:55.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19629" PostTypeId="2" ParentId="14379" CreationDate="2015-09-03T05:43:19.560" Score="0" Body="&lt;p&gt;I don't expect realism from Google Flight Simulator, but in providing a reasonable simulation of real world scenery I haven't seen anything nearly as good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Takeoff scenarios aren't always true to typical flying conditions.  Maybe one or two weeks out of a whole year, planes head east to take off at LAX; at all other times they face west, over the beach and out over the ocean as soon as they take off.  But in Flight Simulator you always fly east from LAX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Google Earth Flightsim works on the Moon and on Mars. Apparently atmospheric conditions are modeled the same as they would be on Earth, since the aircraft seem to behave the same with regard to maximum altitudes and so forth.&lt;/p&gt;&#xA;" OwnerUserId="10071" LastEditorUserId="1696" LastEditDate="2015-09-04T22:22:18.523" LastActivityDate="2015-09-04T22:22:18.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19630" PostTypeId="2" ParentId="19620" CreationDate="2015-09-03T06:18:50.623" Score="10" Body="&lt;p&gt;egid is right. It is called spinner. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The spinner basically covers the part of the hub where the compressor blades are attached and reduces drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nAPr3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nAPr3.jpg&quot; alt=&quot;CFM56 Spinner&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: b737.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also serves other purposes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Diverting the airflow efficiently in the center of the engine so that the airflow is smooth over the compressor blade hub&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KKlgc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KKlgc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;More importantly, the spinner serves to divert the rain and (more importantly) hail impinging on it towards the bypass fan and away from the 'core' of the engine, reducing chances of engine flameout.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The second point an important design parameter for the spinner. According to AGARD-AR-332, &lt;em&gt;Recommended Practices for the Assessment of the Effects of&#xA;Atmospheric Water Ingestion on the Performance and Operability of Gas Turbine Engines&lt;/em&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An effective way to remove a sizable amount&#xA;  of hail from the core is to optimize the spinner shape&#xA;  to deflect hail upon impact directly towards the fan&#xA;  duct.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The spinner of the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56 engine&lt;/a&gt; was modified in response to the engine flameout experienced in &lt;a href=&quot;https://en.wikipedia.org/wiki/Garuda_Indonesia_Flight_421&quot; rel=&quot;nofollow noreferrer&quot;&gt;Garuda Indonesia Flight 421&lt;/a&gt;. The shape was changed into a conelliptical profile.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-03T06:18:50.623" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19634" PostTypeId="1" CreationDate="2015-09-03T08:41:37.980" Score="3" ViewCount="2694" Body="&lt;p&gt;I really want to work in the aviation industry. Is there any way I can put my computer science degree to use in this industry.&lt;/p&gt;&#xA;" OwnerUserId="10075" LastEditorUserId="3775" LastEditDate="2015-09-03T10:12:11.813" LastActivityDate="2015-09-03T10:12:11.813" Title="Really love aviation but have a computer science degree. What kind of jobs could I possibly get which involve aviation?" Tags="&lt;career&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ClosedDate="2015-09-03T13:41:52.723" ContentLicense="CC BY-SA 3.0" />
  <row Id="19635" PostTypeId="2" ParentId="19634" CreationDate="2015-09-03T09:05:21.993" Score="2" Body="&lt;p&gt;I'm not sure if this question comes within the scope of this site the way it is phrased. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, Aviation industry is highly interdisciplinary and has a lot of scope for computer science engineers like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Design of aircraft subsystems&lt;/li&gt;&#xA;&lt;li&gt;Development of programs for design and analysis of aircraft components (CAD, CFD etc).&lt;/li&gt;&#xA;&lt;li&gt;Instrumentation and testing of aircraft systems&lt;/li&gt;&#xA;&lt;li&gt;Development of aircraft control systems (e.g fly by wire)&lt;/li&gt;&#xA;&lt;li&gt;Aircraft testing and telemetry.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft maintenance, which is becoming software intensive.&lt;/li&gt;&#xA;&lt;li&gt;Software for Airborne (avionics) and Ground based systems (e.g. Air traffic Management).&lt;/li&gt;&#xA;&lt;li&gt;Development of aircraft display systems.&lt;/li&gt;&#xA;&lt;li&gt;Software for communication systems for UAVs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This list is by no means exhaustive. In most parts of aviation, there is a requirement for computer science engineers. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-03T09:05:21.993" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19636" PostTypeId="1" AcceptedAnswerId="19640" CreationDate="2015-09-03T09:29:38.583" Score="52" ViewCount="11388" Body="&lt;p&gt;&lt;em&gt;There is &lt;a href=&quot;https://aviation.stackexchange.com/questions/8986&quot;&gt;another question&lt;/a&gt; about airliners and if someone not qualified could land them. My question is about the steps I should take to stay alive in a small GA plane.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Let say a friend of mine invites me aboard a small aircraft (like Cessna 172 or equivalent).&lt;br&gt;&#xA;At some point my pilot friend passes out for some reason. What should I do considering the following:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I'm not a pilot.&lt;/li&gt;&#xA;&lt;li&gt;I'm seated in the co-pilot seat.&lt;/li&gt;&#xA;&lt;li&gt;I spent hundreds of hours on Flight Simulator (a few years ago).&lt;/li&gt;&#xA;&lt;li&gt;I've been initiated to fly a small aircraft (1 session covering the very basics), but no take-off/landing exercises.&lt;/li&gt;&#xA;&lt;li&gt;The weather is good.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft is in good condition.&lt;/li&gt;&#xA;&lt;li&gt;The tank is full.&lt;/li&gt;&#xA;&lt;li&gt;Area has ATC and I know how to operate the radio.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;This is my guess:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Hold the plane's level and heading&lt;/li&gt;&#xA;&lt;li&gt;Slap my friend to try to wake him up&lt;/li&gt;&#xA;&lt;li&gt;Send &quot;Mayday&quot; asking for assistance and technical guidance&lt;/li&gt;&#xA;&lt;li&gt;Try to follow ATC instructions as well as I can&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Does this look good? What should be done differently?  &lt;/p&gt;&#xA;" OwnerUserId="10076" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2019-01-04T13:26:14.833" Title="Pilot passed out in a small GA plane. What can a passenger do?" Tags="&lt;emergency&gt;&lt;general-aviation&gt;" AnswerCount="9" CommentCount="12" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="19637" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T09:40:17.273" Score="5" Body="&lt;p&gt;Here's my guess as a non pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'd probably have to ask your friend in advance how exactly to do 3. I suspect doing 1 and 3 simultaneous will be taxing for anyone who hasn't flown a real aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might want to know how to set the transponder (if present) and what code it should &quot;squawk&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot passed out immediately after take-off before reaching cruise altitude, you might not want to maintain that flight level - there might be trees or hills ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the pilot's order of priorities is aviate, navigate, communicate.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-09-03T09:40:17.273" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19638" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T09:53:35.313" Score="26" Body="&lt;p&gt;This has happened before and it usually ends ok, the most important thing is to keep calm. One suggestion I would have is instead of flying straight and level I would fly a box over the current location while you speak to ATC. This will keep you in range of the ATC station you are talking to and keep you out of trouble. If you fly straight and level the terrain may come up to meet you, you could fly out to sea, or you could blunder into O'Hare's airspace with all the fun that would ensue. Try to maintain the same altitude as if you are at cruise the mixture should be set for that altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few things to add to your list:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You need to apply carburetor heat about every 15 minutes unless the aircraft is fuel injected. If you don't do this your carb could ice up and you could lose power. This is done by pulling the carb heat knob (or lever, depending on the AC) for 20 seconds or so and then pushing it back in&lt;/li&gt;&#xA;&lt;li&gt;Fuel management: depending on the aircraft you may need to switch tanks. A C172 (and most high-wing airplanes) is generally set to both tanks in which case it's not an issue but in low-wing airplanes you will need to regularly switch tanks (say every half an hour) to keep the fuel balanced, otherwise you could run out of fuel in a tank and down you go with a full tank in the other wing. On a PA-28 the fuel selector is by the pilot's left knee which would make things interesting. Make sure you don't accidentally switch the fuel off! &lt;/li&gt;&#xA;&lt;li&gt;Slapping someone isn't the best way to wake them up, pinch their earlobe as hard as you can with as much fingernail as possible, or push a pen into it. It's very painful, if anything will wake him/her that's it&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="4197" LastEditDate="2015-09-03T13:40:24.227" LastActivityDate="2015-09-03T13:40:24.227" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="19639" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T10:23:19.170" Score="4" Body="&lt;p&gt;The feel of the controls is one of the things that you will really have to get your head round really quickly if this is the first time you have touched them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You don't move the controls you just apply a little bit of pressure, unlike a flight sim which has a totally unrealistic feel on the controls, and this alters with the airspeed of the aircraft. You have to be able to handle the aircraft quite precisely to be able to safely land, whereas most people even with flight sim experience take quite a few hours of instruction to be safe enough to go solo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read about a crash in the UK where the pilot was incapacitated and the passenger had been shown how to bail out. He couldn't get the hood open because it was heavy and the aircraft hit the ground with him clawing at the hood. All he needed to do was pull the stick back and he would have had more time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would say, feeling the controls, just try to get the aircraft level and under control and at a constant speed, will be more difficult than you think it might be, and also to stay calm so you can think and relate to what air traffic are saying. This is a lot easier said than done given that you are just about to die if you do something wrong. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just a small thing like not already talking to air traffic and not knowing the emergency frequency (or not knowing where the transmit button is) could panic you and ruin your whole day, or pulling the mixture back instead of the throttle. There are loads of things that could go wrong in real life even though you can fly the sim through a keyboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand if you can reach the ground under control at the correct (slowest safe) speed - about 1.2 - 1.3 times the stall speed, you don't need to speak to anyone or do anything else, the chances are you could live, especially if you reach the ground on an airport where there are emergency services to extract you from the aircraft. But then, you might know the stall speed in the sim, how do you really know it in the real aircraft you are in at the time? None of this is as easy as you think!&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-09-03T11:00:25.690" LastActivityDate="2015-09-03T11:00:25.690" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="19640" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T10:48:38.943" Score="44" Body="&lt;p&gt;Best case scenario: You're straight and level, on frequency with some form of human being, there's no immediate danger and you have the know-how to transmit. In that case, that human will provide you with everything they possibly can to help you. Most important thing for you to do is keep the aircraft away from clouds, away from terrain and not panic. You'll probably be in an aircraft that is more-or-less easy to fly in this situation. Most GA aircraft are quite stable and will not be a beast to control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once talking to ATC they will tell you to set your transponder to a number. You should find somewhere a 4-digit readout with a knob below/above each digit. Set the number indicated to help ATC identify you easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, look around you for big landmarks (Mountains, Lakes, even a large Church/Cathedral) as one of the first things ATC will want to do is work out where you are.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That's best case; let's look at some alternatives. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;You're out of range of the tuned frequency on the radio, or there is no response&lt;/em&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tune 121.5MHz, this is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/809/is-there-a-dedicated-emergency-frequency&quot;&gt;emergency frequency&lt;/a&gt;. Someone will be monitoring this channel and be able to give you further advice - if nothing else a local ATC channel to tune. Failing this see if your pilot has a chart handy, he may have drawn his intended route on it - look along that route for anything that looks like a frequency to tune into the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Aircraft is climbing, or descending&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Get the aircraft into safe, level flight. Remember controls work in the opposite sense to what you might expect (probably not if you've ever played any flight simulator). If the engine is roaring reduce power slightly. If you appear to be losing altitude with the nose on the horizon increase power slightly. Do everything with tiny incremental changes. Try not to fiddle too much with controls, only what is necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Aircraft is heading directly for a cloud/out to the sea/towards a heavily built up area/a big airport&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turn 180 degrees - don't try to turn too quickly, it should take roughly 30 seconds to 1 minute to complete this turn.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are courses which are aimed at non-pilots who regularly fly in the right hand seat. Here's some interesting reading:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/safety/183023-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.avweb.com/news/safety/183023-1.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2019-01-04T13:26:14.833" LastActivityDate="2019-01-04T13:26:14.833" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="19642" PostTypeId="2" ParentId="19609" CreationDate="2015-09-03T11:54:51.323" Score="14" Body="&lt;p&gt;Helicopters currently use lightweight but fairly inefficient gas turbines. Diesel-electric engines have great energy efficiency, in terms of mechanical energy delivered per kilo of fuel. However, they're quite heavy. This means that you need more lift, which in turn means more power is needed. This negates the initial advantage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the advent of lightweight materials, the latter effect decreases so this situation might change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Diesel engines can throttle up and down quite a bit, unlike gas turbines,  but this capacity is irrelevant to helicopters. Note that helicopters need a pretty constant amount of lift. &lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-09-03T11:54:51.323" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19643" PostTypeId="1" AcceptedAnswerId="19644" CreationDate="2015-09-03T12:24:24.943" Score="16" ViewCount="2927" Body="&lt;p&gt;Sometimes in wind tunnel tests, models are suspended upside-down:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/RYkcK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RYkcK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dnw.aero/Skills-and-specialities/Measurement-techniques/Interference-corrections.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image obtained from DNW - Interference corrections&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pFsfw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pFsfw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=Y0GKqp9Lmy0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image obtained from this Youtube video of testing at AEDC&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iRbdI.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iRbdI.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.uwal.org/uwalinfo/techguide/modelsupport.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image obtained from UWAL - Model Support Effects&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And sometimes they are in the normal flying position:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zzNzS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zzNzS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.trimodels.com/testing.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image obtained from TRI models - wind tunnel testing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the specific reason for putting wind tunnel models upside-down?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought it had something to do with minimizing the influence of the support, but putting the plane upside down doesn't change much about the location of the support.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-09-04T08:48:43.327" LastActivityDate="2015-09-04T10:11:11.073" Title="Why are wind tunnel models sometimes placed upside down?" Tags="&lt;wind-tunnel&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19644" PostTypeId="2" ParentId="19643" CreationDate="2015-09-03T12:56:54.210" Score="22" Body="&lt;p&gt;In the times before strain gauges and electronic transducers, the forces on the wind tunnel model were measured with scales. To avoid interference as much as possible, the model was hung on strings, the scales being mounted above the measurement area of the tunnel. Since the forces in upright flight were of the highest interest, gravity plus lift would make sure that the strings were always taut. If the model were hung upright, the lift might grow bigger than the weight, and the model would move towards the scales.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, the orientation of the model can be either way, and only in exceptional cases there is a strong reason for placing it upside down. This might be when unusual attitudes together with the supporting sting (the long spike on which the model sits) would block one part of the wind tunnel cross section too much, or if movement restrictions of the sting force a certain orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is flow visualization techniques: Sometimes it helps to put a coat of a mixture of petroleum and pigments on the surface and to watch where the pigments are blown by the flow (this is called an Anstrichbild). Obviously, it helps to place the surface of interest on top.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="9276" LastEditDate="2015-09-04T10:11:11.073" LastActivityDate="2015-09-04T10:11:11.073" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="19645" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T12:58:56.050" Score="2" Body="&lt;p&gt;This is a good question and your guesses make sense. I’m not a pilot but here is what I’d do (if the plane is small like you say):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A non pilot would definitely be overwhelmed by the controls and buttons and all their meanings. But if you have had some training you could manage. First thing to do would be to establish communications with ATC and explain to them that you are a non pilot who is now in charge. For this you’ll have to put on the pilot’s headset and use the mic button. Say something like &lt;strong&gt;“MAYDAY MAYDAY our pilot has passed out”&lt;/strong&gt;, anyone hearing this would definitely assist (training on a simulator is a plus in this situation.) Gaining a little altitude to get good a good reception is also a good idea.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could also try dialing 121.5 (aircraft emergency frequency ) and call for some help.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The &lt;strong&gt;&lt;em&gt;aircraft emergency frequency&lt;/em&gt;&lt;/strong&gt; (also known as &lt;strong&gt;&lt;em&gt;guard&lt;/em&gt;&lt;/strong&gt;) is a frequency&#xA;  used on the aircraft band reserved for emergency communications for&#xA;  aircraft in distress. The frequencies are &lt;em&gt;121.5 MHz&lt;/em&gt; for civilian, also&#xA;  known as &lt;strong&gt;&lt;em&gt;International Air Distress&lt;/em&gt;&lt;/strong&gt; (IAD) or VHF Guard, and 243.0 MHz&#xA;  for military use, also known as &lt;em&gt;Military Air Distress&lt;/em&gt; (MAD) or UHF&#xA;  Guard. &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_emergency_frequency&quot; rel=&quot;nofollow&quot;&gt;(Wikipedia)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But remember it all happens very fast I'm sure. If the person flying doesn’t screw up completely like touch down at 120 kt or stalling etc. landing would be survivable with minimum injuries to everyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also take the help of five C's that have been devised for the pilots in distress:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In order to circumvent the effects of panic, the five C’s of aviation&#xA;  have been devised. &lt;em&gt;The five C’s are: Confess, climb, conserve fuel,&#xA;  communicate and comply.&lt;/em&gt; &lt;a href=&quot;http://www.golfhotelwhiskey.com/getting-lost/&quot; rel=&quot;nofollow&quot;&gt;(Source)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can try keeping the aircraft clear of terrain, obstructions and densely populated area. Even if you couldn’t reach the ATC flying towards an open terrain or open water is the next best option (God forbid!). &lt;/p&gt;&#xA;" OwnerDisplayName="user10079" LastActivityDate="2015-09-03T12:58:56.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19648" PostTypeId="2" ParentId="15727" CreationDate="2015-09-03T14:41:55.663" Score="2" Body="&lt;p&gt;Every airline pilot is required to maintain currency. In a 2nd officers case most of this will probably be in a full motion simulator.&lt;/p&gt;&#xA;" OwnerUserId="10080" LastActivityDate="2015-09-03T14:41:55.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19649" PostTypeId="1" AcceptedAnswerId="19652" CreationDate="2015-09-03T14:55:12.330" Score="11" ViewCount="2968" Body="&lt;p&gt;After all the media coverage about people pointing lasers at commercial aircraft, I started to wonder what was so special about lasers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to me that the amount of distraction that could be done with a 5mW laser is significantly less than what could be done with something else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if I bought/borrowed &lt;a href=&quot;https://en.wikipedia.org/wiki/Luxor_Las_Vegas#Luxor_Sky_Beam&quot;&gt;the light beam from the Luxor hotel&lt;/a&gt;, put it in my backyard, turned it on, and pointed it at the planes flying out of a major airport, I would expect that pilots might have some more issues with a 4.3 Billion candela beam than with a 5mW laser (right?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I can't find any laws against it, so would this technically be legal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, what if I just wanted to swing that beam around in the sky, and it accidentally crossed the path of a plane?  Are there different laws regarding unintentionally hitting a plane with something like this?&lt;/p&gt;&#xA;" OwnerUserId="987" LastEditorUserId="64" LastEditDate="2015-09-03T16:17:33.527" LastActivityDate="2018-10-17T23:33:57.040" Title="What is the effect of non-LASER light sources on pilots?" Tags="&lt;faa-regulations&gt;&lt;accidents&gt;&lt;regulations&gt;&lt;hypotheticals&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19650" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T16:24:12.437" Score="1" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;As much as possible, keep your hands off of the controls.  A properly trimmed airplane will maintain straight and level flight.  A human likely will not.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tune the radio to 121.5 and call mayday.  121.5 will be monitored everywhere there is any ATC activity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Follow the instructions of ATC.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Use the trim and throttle to descend.  During landing, the elevator (pull back and push forward on the wheel) controls airspeed, the throttle controls altitude.  Trim the airplane and use the throttle to control descent.  More/less trim may be required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="10081" LastActivityDate="2015-09-03T16:24:12.437" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="19651" PostTypeId="2" ParentId="19649" CreationDate="2015-09-03T16:29:19.943" Score="3" Body="&lt;p&gt;The comment by @mins is right on the money by indicating that lasers require much less power to damage and distract than typical lights (whose power density falls off with the square of the distance).  An additional consideration is that, while a Luxor-style beam shining from your yard will certainly get the attention of pilots, it will likely be much easier to trace to its source than a laser beam.  You will likely be contacted.  They may ask you to turn it off, and they may ask you to leave it on, because, while it may be obnoxious, such things are often labeled on the chart because they are uniquely identifiable visual checkpoints.  Such visual checkpoints are named, recorded in the FAA database, and depicted on Terminal charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking of the Luxor, I believe there was a visual approach procedure that actually used the Luxor as a visual fix, although I do not see it published with the current procedures.&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="22726" LastEditDate="2018-10-17T23:33:57.040" LastActivityDate="2018-10-17T23:33:57.040" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="19652" PostTypeId="2" ParentId="19649" CreationDate="2015-09-03T16:45:27.340" Score="12" Body="&lt;p&gt;The short answer is &quot;If you intentionally pointed the Luxor beam at an aircraft (flying low enough for it to constitute a hazard) you would probably be arrested&quot;.  The real question is &lt;em&gt;What would they charge you with?&lt;/em&gt;, and the &lt;em&gt;FAA&lt;/em&gt; regulations aren't where you want to look for that: You need to look in the &quot;United States Code&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/USCODE-2012-title18/html/USCODE-2012-title18-partI-chap2-sec39A.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;18 U.S.C. 39A&lt;/a&gt; makes it an offense to aim a laser pointer at an aircraft. It goes on to define &quot;laser pointer&quot; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;any device designed or used to amplify electromagnetic radiation by stimulated emission that emits a beam designed to be used by the operator as a pointer or highlighter to indicate, mark, or identify a specific position, place, item, or object.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Luxor beam certainly isn't that, so you're safe there.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead you will probably be charged under a creative application of &lt;a href=&quot;http://www.gpo.gov/fdsys/pkg/USCODE-2011-title18/html/USCODE-2011-title18-partI-chap2-sec32.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;18 U.S.C. 32(a)(5)&lt;/a&gt;, which says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Whoever willfully … interferes with or disables, with intent to endanger the safety of any person or with a reckless disregard for the safety of human life, anyone engaged in the authorized operation of such aircraft or any air navigation facility aiding in the navigation of any such aircraft … shall be fined under this title or imprisoned not more than twenty years or both.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While this law was originally conceived to deal with in-person threats (kicking down the cockpit door and clobbering the captain with a frying pan) it would not take a very creative US Attorney to make the argument that shining a 40 billion candela light at an aircraft's cockpit would &quot;interfere with or disable&quot; the flight crew, and shows a &quot;reckless disregard for the safety of human life&quot;.&lt;br&gt;&#xA;Similarly it would not take much creativity to argue that swinging such a beam around in the sky in an area where it may interfere with aircraft operations would also show a &quot;reckless disregard for the safety of human life&quot;, unless you took the time to file an appropriate hazard NOTAM.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that in my initial statement I said that you would be charged if the aircraft were flying &quot;low enough for it to constitute a hazard&quot; -- as has been pointed out non-coherent light source intensity falls off &lt;a href=&quot;https://en.wikipedia.org/wiki/Inverse-square_law&quot; rel=&quot;nofollow noreferrer&quot;&gt;according to the inverse square law&lt;/a&gt;, and with sufficient altitude the Luxor beam is just a bright spot on the ground and doesn't have anywhere near the effects of &lt;a href=&quot;https://aviation.stackexchange.com/questions/2817/why-is-laser-illumation-of-a-cockpit-an-emergency&quot;&gt;laser illumination&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Luxor's beam was in fact &lt;a href=&quot;http://www.laserpointersafety.com/LPSFiles/files/TNO-DV%202009%20C264.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;part of a study on the effect of lasers and high intensity lights in relation to air traffic safety&lt;/a&gt;. That section of this report (and indeed the entire thing) makes for interesting reading.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="22726" LastEditDate="2018-10-17T23:30:54.207" LastActivityDate="2018-10-17T23:30:54.207" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="19654" PostTypeId="2" ParentId="19643" CreationDate="2015-09-03T18:44:58.823" Score="6" Body="&lt;p&gt;The main reason for placing the wind tunnel models upside down was that it was &lt;a href=&quot;http://history.nasa.gov/SP-440/ch2-6.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;easier to measure lift&lt;/a&gt; that way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first wind tunnels faced two main problems while measuring body forces:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How to avoid interference- This was overcome by either suspending the model on wires or placing the model on a metal pole called stinger that projected to the rear side of the model.&lt;/li&gt;&#xA;&lt;li&gt;How to measure the forces accurately. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The forces on the initial wind tunnels were mostly measured using force balance. In case of the models suspended on wires, 'tare' weight can then be set and any additional balance weight required is the lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/euJpt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/euJpt.jpg&quot; alt=&quot;Wind tunnel Mass Balance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though the wind tunnels became more sophisticated,the models were mounted upside down both as force of habit and as measuring equipments were designed for that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the lift could be measured the other way too and some wind tunnels followed that. There is no fundamental difference between the two. Certain wind tunnel tests like separation studies require the models be mounted in a particular (usually right way up) orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In today's wind tunnels using strain gages among other things, the models can be mounted in any required orientation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-03T18:44:58.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19655" PostTypeId="2" ParentId="17535" CreationDate="2015-09-03T18:51:24.680" Score="1" Body="&lt;p&gt;The nose design can have an effect on the aircraft but that depends on the type of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small single engine GA aircraft the nose area behind the propellor is critical. Generally known as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cowling&quot; rel=&quot;nofollow noreferrer&quot;&gt;cowling&lt;/a&gt; over the years it has has many different designs. The varying designs have had drastic effects on engine cooling and drag depending on the plane. &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/1997/July/1/Modding-Mooneys&quot; rel=&quot;nofollow noreferrer&quot;&gt;Early Mooney's&lt;/a&gt; suffered from a less than idea cowling and mods gained them a lot of speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For jets like the ones you have pictured there are few things to  consider in &lt;a href=&quot;https://en.wikipedia.org/wiki/Nose_cone_design&quot; rel=&quot;nofollow noreferrer&quot;&gt;nose cone design&lt;/a&gt;. First off (although this has no aerodynamic effect). There is equipment housed behind the nose cone. Often radar and other things so the nose generally needs to able to accommodate that. Drag is a consideration when designing the nose as well, here is a nice chart regarding the drag on various designs.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YZ6jP.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YZ6jP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a pretty &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a548461.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;lengthy paper on missile design&lt;/a&gt; that covers nose cones a bit as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For supersonic planes there are other considerations as well such as the shock wave produced and other things that are out of my body of knowledge but Im sure someone here can weigh in. One very interesting nose is that of the Concorde. On one hand it had its &lt;a href=&quot;http://www.concordesst.com/nose.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;awesome moveable system&lt;/a&gt; which allowed for greater visibility on takeoff and landing and a more streamline (and heat treated glass) for super sonic flight. But perhaps more interestingly the plane had a serious nose heat issue. They solved this by pumping fuel through the nose as a form of coolant.       &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-09-03T19:09:49.160" LastActivityDate="2015-09-03T19:09:49.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19656" PostTypeId="2" ParentId="19636" CreationDate="2015-09-03T19:25:39.030" Score="22" Body="&lt;p&gt;Just thought I'd add an answer about &quot;aviate&quot;, &quot;navigate&quot;, &quot;communicate&quot; which is discussed somewhat in the comments and is a big part of what you should do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's simply a matter of dealing with the most important things in order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviate - fly the aircraft (keep it flying) - if you fail to do this, it will almost certainly kill you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigate - fly where you want to go.  In this case, do as little as you have to to avoid obstacles, terrain and clouds.  Don't worry about bimbling into controlled airspace - someone else will take care of it.  Don't try to be clever and fly circuits or boxes or whatever.  Without at least a few hours proper training, trying to navigate could well lead to you forgetting or failing to aviate.  Not navigating away from clouds, obstacles etc is the second most likely thing to kill you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Communicate - tell someone about it.   Not doing this won't kill you but could stop you getting help with one and two not killing you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mayday on the frequency already tuned.  Use the mnemonic &quot;Rest In Peace Louis Hoy&quot; if you can remember it.  R for reason, I for intent.  P for position, L for level (altitude), H for heading.  If you can't handle it, a simple &quot;mayday&quot; will start the ball rolling.  If all you say is the word &quot;mayday&quot; or &quot;emergency&quot;, if anyone hears you, they will reply &quot;station calling, say again&quot; or &quot;station calling, pass your message&quot; or similar.  This just means they got it, but don't know who you are.  The conversation has started, let the person you're talking to do the work and ask questions as needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If no-one replies, and you can remember the frequency, tune 121.5 - the international distress frequency for VHF.  Someone will hear that and quite likely be able to triangulate your position.  Tuning the transponder to 7700 will also get a lot of attention.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not communicate, even if someone is calling you, if it takes your attention away from aviating and navigating.  If you can, a simple &quot;standby&quot; in response will tell the caller all they need to know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sadly far too many people have died because they failed to follow this simple advice which has been proven over many, many years and 10s of thousands of urgent situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember.  In the ongoing battle between the Earth and aircraft arriving in other than controlled conditions, the Earth has yet to lose.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-04T11:12:52.257" LastActivityDate="2015-09-04T11:12:52.257" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="19657" PostTypeId="1" CreationDate="2015-09-03T20:09:34.513" Score="6" ViewCount="7947" Body="&lt;p&gt;There are how many I.C.A.O. PANS? What are their basic contents? I have tried a lot in internet, but could not find out.&lt;/p&gt;&#xA;" OwnerUserId="9221" LastEditorUserId="595" LastEditDate="2015-09-03T20:17:18.500" LastActivityDate="2017-11-04T14:43:36.140" Title="What are the ICAO PANS? What are their contents?" Tags="&lt;icao&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19659" PostTypeId="2" ParentId="19232" CreationDate="2015-09-03T20:18:30.690" Score="18" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a maximum airspeed to deploy a ram air turbine?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The ram air turbine (RAT) can be extended and used at any speed above a minimum speed, because under this minimum speed, power is difficult to generate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generated power may be decreased below 130 knots, and extension is prevented below 100 knots because of additional drag produced for nearly no power obtained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RAT can be extended automatically (loss of engines or pressure) and manually, e.g. logic for RAT extension on A330 (note the inhibition by airspeed below 100 kt and by on-the-ground sensor:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V2kPy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V2kPy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=A330-Hydraulic.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A330 FCOM - Hydraulics&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Can airspeed be determined from the rate of its propeller rotation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, the RAT turns at constant speed to produce a constant AC frequency or hydraulic pressure or both. The rotational speed is stabilized by a governor which adjusts the angle of attack of the blades according to airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the governor fails to maintain the speed, there is a security to prevent overspeed and blade damage/release.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ieee.rackoneup.net/rrvs/06/Emergency%20RATs%20Presentation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Emergency Airplane RATs&lt;/a&gt;, Michael J. Zolidis, Hamilton Sundstrand, 2006.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A ram air turbine from Hamilton Sundstrand has a mechanical speed governor to vary the RAT blades angle according to the airspeed, and maintain a constant rotational speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At low speed, the blade angle is maintained near-perpendicular to the airflow to extract the most energy possible. When the ram speed increases, the angle is progressively reduced.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;HS seems to measure the RAT power at 130 KEAS (Knots Equivalent Air Speed), e.g. &lt;em&gt;the A380 RAT is 62” (1.57 m) diameter and delivers 85 HP (63 kW) at 130 KEAS&lt;/em&gt;. This mean at 130 KEAS or above, the full power is delivered.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.vertoonbaar.nl/arb/wp-content/uploads/Uncommanded-RAT-extensions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Uncommanded Ram Air Turbine (RAT) extensions&lt;/a&gt; - Airbus&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The RAT auto-deploys when both engines fail, or manually from a panel overhead. It's prevented to deploy on the ground, and below 100 KCAS&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The speed value is provided by the ADIRU.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The RAT is able to be extended in all flight envelope conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://fsbrasil.files.wordpress.com/2009/01/e190_airplane-operations-manual-aom-1502-017-rev-04_apr-30-2010.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Embraer 190 - Airplane Operations Manual&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is no maximum altitude or speed for RAT deployment&lt;/li&gt;&#xA;&lt;li&gt;Deployment occurs whenever AC buses are not powered or manually.&lt;/li&gt;&#xA;&lt;li&gt;RAT deployment takes 8 seconds.&lt;/li&gt;&#xA;&lt;li&gt;RAT has its full capacity at 130 KEAS or above.&lt;/li&gt;&#xA;&lt;li&gt;Below 130 KEAS, only the AC bus is powered. DC buses are powered by the batteries, as well as the standby AC bus through a DC/AC converter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.caa.co.uk/docs/33/CAP513.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ETOPS CAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For ETOPS, three electrical power sources are required. If the RAT is one of them, it must be demonstrated as reliable (extension and generation).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The extension mustn't rely on engine power :-)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The most popularized RAT use may be for &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC143 &lt;em&gt;Gimli Glider&lt;/em&gt;&lt;/a&gt;, with a dual engine loss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;RAT article&lt;/a&gt; on Wikipedia.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=1OYsFCjusps&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320 RAT extension and retraction&lt;/a&gt; on Youtube.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tGcsX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tGcsX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Bombardier BD700-1A11 Global 5000 (&lt;a href=&quot;http://gvabizjets.blogvie.com/2013/08/06/bombardier-bd700-1a11-global-5000-m-cccp-cn-9418-gva-august-4-2013-photos-jean-luc/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320 Flight test (&lt;a href=&quot;http://thaiflight.com/mach/modules.php?name=Forums&amp;amp;file=viewtopic&amp;amp;t=53052&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Bombardier CRJ700 (&lt;a href=&quot;http://aeronantesspotters.forumactif.com/t729-spotting-du-01-10-2011&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;US Navy T-45A (&lt;a href=&quot;https://www.flickr.com/photos/james_orear/3985649356&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Airbus A330 (&lt;a href=&quot;http://www.elakiri.lk/forum/showthread.php?t=1614534&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Boeing B747-8 (picture by Gregor Schläger, &lt;a href=&quot;http://www.gregorschlaeger.de/Bilddaten/Catalogs/120514_B747_800/120514_RAT1463.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Boeing B777, RAT extension switch (&lt;a href=&quot;http://www.pilote-virtuel.com/viewtopic.php?pid=611958&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-09-30T19:05:11.970" LastActivityDate="2019-09-30T19:05:11.970" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="19660" PostTypeId="1" AcceptedAnswerId="19663" CreationDate="2015-09-03T20:39:38.920" Score="0" ViewCount="579" Body="&lt;p&gt;I'm reading the &lt;a href=&quot;http://uavsar.jpl.nasa.gov/science/documents/polsar-format.html&quot; rel=&quot;nofollow&quot;&gt;UAVSAR data format&lt;/a&gt; and in &lt;strong&gt;File Naming Convention&lt;/strong&gt; section is said that if we take a typical file name:  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Dthvly_34501_08038_006_080731_L090HH_XX_01.slc  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;as the name that follows  &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Dthvly_34501_08038_006_080731_L  (090)  HH_XX_01.slc  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The three digits that are in parentheses, is the &lt;strong&gt;steering angle&lt;/strong&gt;.&lt;br&gt;&#xA;And for the above file name, we have:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dthvly is the site name, 345 degrees is the heading of UAVSAR in&#xA;  flight, with a counter of 01, the flight was the thirty-eighth flight&#xA;  by UAVSAR in 2008, this data take was the sixth data take during the&#xA;  flight, the data was acquired on July 31, 2008 (UTC), the frequency&#xA;  band was L-band, &lt;strong&gt;pointing at perpendicular to the flight heading (90&#xA;  degrees counterclockwise)&lt;/strong&gt;, this file contains the HH data, this is the&#xA;  first interation of processing, cross talk calibration has not been&#xA;  applied, and the data type is SLC.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is &lt;strong&gt;steering angle&lt;/strong&gt;?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please explain very simply because I'm not very familiar with aviation concepts. I just want to have a sense and intuition about of the aircraft &lt;strong&gt;steering angle&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="10087" LastActivityDate="2015-09-03T21:28:19.350" Title="What does steering angle mean?" Tags="&lt;navigation&gt;&lt;flight-planning&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2015-09-03T23:05:15.097" ContentLicense="CC BY-SA 3.0" />
  <row Id="19662" PostTypeId="1" AcceptedAnswerId="20670" CreationDate="2015-09-03T21:22:37.840" Score="6" ViewCount="5352" Body="&lt;p&gt;The Boeing 747-8 has a new airfoil design much different than a Boeing 737's airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737 airfoil:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uZRJ5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uZRJ5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://haadbinhasan.blogspot.fr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;How Airplanes Fly?&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-8 airfoil:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x1iWl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x1iWl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2010_q3/2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a little confused of why it is shaped like this. What are the advantages of this new profile?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also more thin, wouldn't that reduce the amount of fuel stored in the wings?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="19" LastEditDate="2016-10-17T13:27:10.083" LastActivityDate="2016-10-17T13:27:10.083" Title="What are the advantages of the B747-8 airfoil over B737's airfoil?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;airfoil&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="19663" PostTypeId="2" ParentId="19660" CreationDate="2015-09-03T21:28:19.350" Score="1" Body="&lt;p&gt;Steering angle, according to the text you bolded:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;pointing at perpendicular to the flight heading (90 degrees counterclockwise)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;means the steering angle &lt;code&gt;090&lt;/code&gt; is the angle, relative to the flight heading counterclockwise, that the data sample was taken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the flight heading was 345 degrees, 90 degrees counter clockwise (CCW) is 255 degrees.  This steering angle has no aviation context and is just a relative offset from the aircraft heading for data acquisition (which in this case sounds like a radar sample).&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-03T21:28:19.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19664" PostTypeId="1" AcceptedAnswerId="19666" CreationDate="2015-09-03T21:32:17.960" Score="8" ViewCount="1268" Body="&lt;p&gt;It looks like a second fan or something. &lt;img src=&quot;https://i.stack.imgur.com/6LfFd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="5517" LastEditDate="2015-09-04T12:25:37.463" LastActivityDate="2015-09-04T12:25:37.463" Title="What are these strange blades behind the N1 fan in a Boeing 747-8 engine?" Tags="&lt;boeing-747&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19666" PostTypeId="2" ParentId="19664" CreationDate="2015-09-03T21:43:07.743" Score="16" Body="&lt;p&gt;Those are Outlet Guide Vanes / Fan Exit Guide Vanes. They prevent the flow (bypass flow in this case) from rotating. The these vanes do not rotate, they are fixed to the housing. They also provide structural support. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because there is no energy lost on the rotation of the flow the efficiency is increased. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-03T22:22:52.127" LastActivityDate="2015-09-03T22:22:52.127" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="19667" PostTypeId="2" ParentId="19657" CreationDate="2015-09-03T22:15:06.580" Score="7" Body="&lt;p&gt;ICAO Procedures for Air Navigation Services (PANS) are documents approved by the ICAO counsel and recommended to states for worldwide application. As such they attempt to make air navigation services uniform across the world. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are five PANS:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;h3&gt;Procedures for Air Navigation Services - Air Traffic Management&lt;/h3&gt; (ICAO document 4444, a.k.a. PANS-ATM) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifies the actual procedures to be used by air traffic service units in providing the various air traffic services to air traffic.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;h3&gt;Procedures for Air Navigation Services - Aircraft Operations&lt;/h3&gt;  (ICAO document 8168, a.k.a. PANS-OPS)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lays down rules for designing instrument approach and departure procedures. Such procedures are used to allow aircraft to land and take off when instrument meteorological conditions (IMC) impose instrument flight rules (IFR).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;h3&gt;Procedures for Air Navigation Services - Abbreviations and Codes&lt;/h3&gt;  (ICAO document 8400, a.k.a. PANS-ABC)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is a list of abbreviations and codes commonly used in aviation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;h3&gt;Procedures for Air Navigation Services - Aerodromes&lt;/h3&gt;  (ICAO document 9981, a.k.a. PANS-ADR)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This details aerodrome licensing and Aerodrome Manuals &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Finally there is the PANS Training which details ISD (instructional Systems Deisgn and Systems Approach to Training (SAT) which enables criterion based and material dependent methodical learning&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2017-02-20T14:39:18.443" LastActivityDate="2017-02-20T14:39:18.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="19669" PostTypeId="1" AcceptedAnswerId="19670" CreationDate="2015-09-03T23:20:42.193" Score="15" ViewCount="4689" Body="&lt;p&gt;GE (General Electric) flies Boeing 747s equipped with new engines that are being tested. Why can't they equip the test airplane with all 4 of the new engines? Wouldn't the thrust be imbalanced by replacing only 1 engine? As you can see, it may have 1 big engine and 3 smaller ones:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gDZfam.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gDZfam.jpg&quot; alt=&quot;747 with GE-90 engine fitted for testing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other times, smaller engines are being tested. Would the smaller engine provide enough thrust for a large, heavy airplane like the 747?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BbrLVm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BbrLVm.jpg&quot; alt=&quot;747 with CFM LEAP engine fitted for testing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-09-04T16:36:39.743" LastActivityDate="2015-09-04T16:36:39.743" Title="Why doesn't GE replace all 4 engines for on their flying test bed instead of just 1?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;boeing-747&gt;&lt;flight-testing&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="19670" PostTypeId="2" ParentId="19669" CreationDate="2015-09-03T23:26:57.580" Score="45" Body="&lt;p&gt;They only change one, because that one is a new engine that is being tested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are testing a new engine you change 1 at first so if it fails you have 3 others.  If you change all 4 and there is a systematic defect in the design, now you have 0 good engines instead of 3.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You will also see that the test engine isn't always one suitable for a 747.  This is because they may be testing a new design or a new alternative fuel and it is safer to test an unknown with 3 good engines (e.g. a 747) rather than with just 1 good engine (any two-engine airplane).  This increases the safety margin if the test engine fails.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Running a different engine with a different thrust rating requires some thought about asymmetric thrust.  Doing this on a 4-engine airplane simplifies this greatly over a 2-engine airplane.  Ways to accommodate different thrust from the odd engine:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;De-rate the new engine so it only produces thrust equivalent to the normal engine&lt;/li&gt;&#xA;&lt;li&gt;Run the new engine at reduced thrust&lt;/li&gt;&#xA;&lt;li&gt;If the new engine is inboard, reduce the outboard engine thrust to balance the total yawing moment from that wing with the other side.&lt;/li&gt;&#xA;&lt;li&gt;Don't worry about it and trim the airplane to compensate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The other advantage to doing this on a 747 is that a 4th engine is technically not really needed as a 747 can takeoff, fly and land with only 3 operating engines. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-09-04T14:33:15.467" LastActivityDate="2015-09-04T14:33:15.467" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="19671" PostTypeId="1" CreationDate="2015-09-04T00:35:50.710" Score="10" ViewCount="7749" Body="&lt;p&gt;Where can a civilian get high g-force training/testing in a centrifuge?  (Likely by paying.)  Preferably with and without a g-suit.  Preferably based in the US, maybe Canada.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm betting the US Air Force centrifuge in San Antonio, Texas, and Canada's military centrifuge in Toronto would laugh and/or hang up the phone if asked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crossing my fingers there's a private or educational facility that would be an option.&lt;/p&gt;&#xA;" OwnerUserId="10052" LastEditorUserId="62" LastEditDate="2015-09-04T00:38:28.140" LastActivityDate="2019-02-23T02:06:48.227" Title="Where can a civilian obtain centrifuge training/testing?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;g-forces&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="20669" PostTypeId="2" ParentId="19662" CreationDate="2015-09-04T01:14:33.067" Score="4" Body="&lt;p&gt;Some things to keep in mind when comparing two very different planes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737NG is the latest version of the 737, and it was designed in the 90's. The design changes included a &lt;a href=&quot;http://www.b737.org.uk/flightcontrols.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;new wing&lt;/a&gt;. The 737 is designed for short flights, with a top range of about 3,000 nmi. The 737 has a design cruise speed of about M0.78.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747-8 is the latest version of the 747, and it was designed in the 2000's. The design changes also included a new wing. The 747 is designed for long flights, with a typical max range of 7,700 nmi. The 747 has a design cruise speed of about M0.85, and is much larger than the 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the two planes span at least a decade, and are optimized for very different profiles. The 747 will be optimized more for cruise, and at a higher speed. The 737 will be optimized less for cruise and more for shorter segments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point is that the airfoil is not uniform along the wingspan. As the 737 link shows, the airfoil shape will change along the span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the two flight profiles include cruise speeds of around M0.8, which means that both planes will be optimized with a supercritical airfoil, as is explained in &lt;a href=&quot;https://aviation.stackexchange.com/a/20670/1696&quot;&gt;another answer&lt;/a&gt;. Therefore both airfoils will have much more in common with each other than compared to, for example, an aerobatic plane. I'm not sure where you got the idea that your first image is a 737 airfoil. The source site just says it is typical for a &quot;stunt plane&quot;, which the 737 is not.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-04T14:20:03.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20670" PostTypeId="2" ParentId="19662" CreationDate="2015-09-04T02:57:01.030" Score="11" Body="&lt;p&gt;The airfoil profile you've shown is called a &lt;em&gt;supercritical&lt;/em&gt; airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical airfoil sections are curved on the top and the bottom. The airflow over the top of the airfoil is accelerated i.e. the airspeed over the top of the airfoil is more compared to the free stream velocity. The associated reduced pressure helping to create lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3MhOL.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3MhOL.png&quot; alt=&quot;Laminar flow over NACA airfoil&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.symscape.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the figure, two things can be inferred:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The pressure over the upper surface is lower compared to the lower surface&lt;/li&gt;&#xA;&lt;li&gt;The pressure gradient is favorable in the forward section of the airfoil (where most of the lift is produced), while the gradient is &lt;em&gt;adverse&lt;/em&gt; in the rear half, which can cause boundary layer transition and possibly separation, if the gradient is too severe.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IiPev.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IiPev.png&quot; alt=&quot;Adverse pressure gradient&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: code7700.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For low speeds (and low angles of attack), this causes no problem in lift generation. However, most of commercial airliners fly at in the transonic regime (with speeds ~ Mach 0.9), the flow over the top of the wing may reach supersonic speeds even when the aircraft itself is flying at subsonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rqy0M.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rqy0M.gif&quot; alt=&quot;Transonic flow over an airfoil&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source:fluid.mech.ntua.gr&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The speed at which this happens (flow over wings becomes supersonic) is called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Critical_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;critical Mach number&lt;/a&gt;. The flow decelerates through a normal shock wave, resulting in a severe adverse pressure gradient over the rear of the airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2lo5C.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2lo5C.gif&quot; alt=&quot;NACA 0012 in transonic flow- Pressure&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: fluid.mech.ntua.gr&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This causes serious problems like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The adverse pressure gradient over the shock wave causes flow separation, decreasing lift and increasing drag. The speed above which the drag increases significantly is called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;drag divergence Mach number&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gQHOe.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gQHOe.jpg&quot; alt=&quot;Schileren photo of flow seperation&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: history.nasa.gov&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;As the speed increases, the shock wave moves to the rear, as does the lift producing region. This causes a nose down pitching moment and stability issues.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LNUcn.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LNUcn.png&quot; alt=&quot;Transonic flow patterns&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Transonic_flow_patterns.svg#/media/File:Transonic_flow_patterns.svg&quot; rel=&quot;noreferrer&quot;&gt;Transonic flow patterns&lt;/a&gt;&quot; by U.S. Federal Aviation Administration - Airplane Flying Handbook. U.S. Government Printing Office, Washington D.C.: U.S. Federal Aviation Administration, p. 15-7. FAA-8083-3A.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The supercritical airfoils are designed to overcome (or delay) these problems. Designed by &lt;a href=&quot;https://en.wikipedia.org/wiki/Richard_T._Whitcomb&quot; rel=&quot;noreferrer&quot;&gt;Richard Whitcomb&lt;/a&gt;, the main characteristics of these airfoils are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;'flattened' upper surface&lt;/li&gt;&#xA;&lt;li&gt;highly cambered aft section&lt;/li&gt;&#xA;&lt;li&gt;smaller leading edge radius compared to the traditional airfoils (that is why they are so thin)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ifql3.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ifql3.gif&quot; alt=&quot;Supercritical airfoil&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: aerospaceweb.org&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantages of supercritical airfoils are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It increases the drag divergence Mach number. For example, in the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;F-111&lt;/a&gt;, the drag divergence Mach number was increased from 0.76 to 0.88, a 16% increase.&lt;/li&gt;&#xA;&lt;li&gt;The shock waves are developed further aft when compared to the normal airfoils&lt;/li&gt;&#xA;&lt;li&gt;They greatly reduce the shock induced boundary layer separation, reducing drag&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The figure below shows a supercritical airfoil in a transonic flow. Note the location of the normal shock compared to the 'normal' airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rhL0a.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rhL0a.png&quot; alt=&quot;Supercritical airfoil&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: space.bas.bg&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The supercritical airfoils were not available when the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737&lt;/a&gt; was first designed. However, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;noreferrer&quot;&gt;737 NG&lt;/a&gt; airfoil incorporates elements of supercritical design,as does the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;noreferrer&quot;&gt;Boeing 747-8&lt;/a&gt; airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The supercritical airfoils reduce the fuel required, as they allow the aircraft to cruise at higher speeds with lesser drag. Additionally, the Boeing 747-8 has a wing span of ~68 m, which gives plenty of storage space for fuel. Also, improvements in engines and airfoils means that the 747-8 has nearly 50% more range compared to the original &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;noreferrer&quot;&gt;747-100&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-09-04T12:15:31.840" LastActivityDate="2015-09-04T12:15:31.840" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20671" PostTypeId="2" ParentId="19649" CreationDate="2015-09-04T03:22:16.250" Score="0" Body="&lt;p&gt;A simple pointer-type laser will not be as bright as a search light, however, there are more powerful lasers, such as those used in light shows that can be quite dangerous. High power lasers at 500 mW are 100x stronger than a 5mW laser pointer and can seriously dazzle a cockpit, filling it with sparkling light so that nothing else can be seen. Lasers of this power can also burn the retina of the eye if the aircraft is flying low enough.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-09-04T03:22:16.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20672" PostTypeId="2" ParentId="19568" CreationDate="2015-09-04T04:55:55.583" Score="3" Body="&lt;p&gt;Short answer: &lt;a href=&quot;https://books.google.com/books?id=eJ7oCAAAQBAJ&amp;amp;pg=PA270&amp;amp;lpg=PA270&amp;amp;dq=Junkers+patent+corrugated+skin&amp;amp;source=bl&amp;amp;ots=YAoWRhfQtb&amp;amp;sig=wU6j8duORW3mTuKhdoyfQ34Dr5o&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0CCUQ6AEwAWoVChMIveLB1KjhxwIVjTyICh1usAcD#v=onepage&amp;amp;q=Junkers%20patent%20corrugated%20skin&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;To stiffen the skin in the direction of the corrugations&lt;/a&gt;, also the direction of flight, &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers&quot; rel=&quot;nofollow noreferrer&quot;&gt;without adding internal structure or assembling multiple pieces that would increase weight&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flat metal sheet was rolled to profile and bent to 3 dimensional form. The corrugations held the form along their length. Flat sheet would have required ribs, stringers or other formers to hold the shape. Corrugations have material in shear in the depth of one dimension, as well as across the length and width of the sheet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This technique was used in other contemporary aircraft as well: The 1930s Polish PZL-7..11..24 family of fighters had corrugated skin on wings and tail surfaces, but not the large, rounded corrugations Junkers used.  Pulawski's designs made use of the Wibault-patented all metal construction that was licensed to build Wibault 7s and 72s in Poland. Vickers also licensed Wibault's patents and &lt;a href=&quot;https://www.google.com/patents/US1760332&quot; rel=&quot;nofollow noreferrer&quot;&gt;their US patent shows and explains how a corrugated skin with smaller corrugations works.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-11/YF-12/SR-71 family have corrugated skin in their wings. In their case, the corrugation allows the whole air frame to expand and contract with heating and cooling. As with Junkers, PZL, Piper, etc, Lockheed's corrugations are chordwise, stiffening the skin fore and aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some post-WWII designs had a sandwich of corrugated inner skin and smooth outer skin, like Junker's early steel-skin airplanes.  Inspection/maintenance/corrosion protection must require focused attention and cost more in later years. But rolling and laminating constant gauge sheet has to cost less than integrally machined skins...&lt;/p&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="64" LastEditDate="2016-11-09T20:14:33.050" LastActivityDate="2016-11-09T20:14:33.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20673" PostTypeId="2" ParentId="19671" CreationDate="2015-09-04T05:02:19.013" Score="4" Body="&lt;p&gt;This is a tough one. I don't know of any civilian facilities (but it does not mean they don't exist). This is a bit of a shot in the dark but in my opinion you may want to contact NASA about the &lt;a href=&quot;http://www.nasa.gov/ames/research/space-biosciences/20-g-centrifuge&quot; rel=&quot;nofollow&quot;&gt;Ames Research Center 20-G centrifuge&lt;/a&gt;. If for no other reason than this is the only non military one that seems to exist. For what its worth high speed centrifuges are not that simple despite just being something that spins in a circle. The speeds that the unit spin at are extremely high to say the least, to do this with out ripping the whole thing apart requires careful balancing and construction so they are not exactly something you can build at home. Here is at least &lt;a href=&quot;http://www.amst.co.at/en/training-simulation-products/human-training-centrifuge/&quot; rel=&quot;nofollow&quot;&gt;one company&lt;/a&gt; that is building them and installing them elsewhere in the world. They list a bunch of installs for other militaries that might be more open to a civilian coming in but who knows.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-04T05:02:19.013" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20674" PostTypeId="2" ParentId="19669" CreationDate="2015-09-04T06:38:25.290" Score="9" Body="&lt;p&gt;They are not testing that the engine works, that's already been proven with hundreds of hours of regulated and rigorous ground running.  They are testing the &quot;on wing&quot; systems and behaviours in various flight conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The on wing systems will also have been tested in ground runs before the first flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, only one engine is needed.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-04T06:44:08.473" LastActivityDate="2015-09-04T06:44:08.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20676" PostTypeId="2" ParentId="19669" CreationDate="2015-09-04T10:09:00.390" Score="6" Body="&lt;p&gt;Although you already have a correct answer and it is accepted too but i would add another point to the mix. They are testing a new engine which uses a new technology and is uncertified/unproven. Why should they make 4 of that version and then find out a number of things to fix and go back to all 4 of them first before moving on to produce more models? That costs a lot of money and time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One is enough.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wouldn't the thrust be imbalanced?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Even on our R/C Aircrafts we can have different engine RPMs for different engines (on a multi engine model), let alone a Jumbo Jet! They can all operate at different turbine speeds and different thrust levels to balance as and when needed.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="1048" LastEditDate="2015-09-04T13:15:39.867" LastActivityDate="2015-09-04T13:15:39.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20682" PostTypeId="1" AcceptedAnswerId="20683" CreationDate="2015-09-04T13:00:57.087" Score="10" ViewCount="1288" Body="&lt;p&gt;Most accidents are referred to by flight number, for instance MH17 or MH370 to name a few recent ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight numbers are &lt;em&gt;usually&lt;/em&gt; but not always retired after a crash. So why isn't referred to the registration number instead?&lt;/p&gt;&#xA;" OwnerUserId="2556" LastEditorUserId="2556" LastEditDate="2018-12-10T07:27:12.870" LastActivityDate="2018-12-10T07:27:12.870" Title="Why is an accident referred to by flight number instead of registration number of the airframe?" Tags="&lt;accident-investigation&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="20683" PostTypeId="2" ParentId="20682" CreationDate="2015-09-04T13:37:20.047" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Most accidents are referred to by flight number&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It depends who it is that is referring to the accident, and on who they are addressing.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;News media and the general public&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Newpapers and other media use flight numbers because that is the number known to friends and relatives of the individuals concerned and because most members of the public who have flown as passengers are very familiar with  the concept of flight numbers but not really familiar with aircraft registration numbers.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Investigators&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Investigating authorities have their own numbering schemes for accidents they investigate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft registration numbers change when an aircraft is sold to a purchaser based in another country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only number that stays with an aircraft for its entire life is the manufacturer's serial number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All these numbers can appear in official accident investigations reports. The registration number is usually prominent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.gov.uk/aaib-reports/2-1990-boeing-747-121-n739pa-21-december-1988&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g0goM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;AAIB&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20020123X00106&amp;amp;key=1&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qHkaU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;NTSB&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/49ED2.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;BEA&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-09-04T16:28:34.363" LastActivityDate="2015-09-04T16:28:34.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20684" PostTypeId="5" CreationDate="2015-09-04T14:06:43.770" Score="0" Body="&lt;p&gt;A Russian aerospace and defense company founded in 1922 by Andreï Tupolev. The company designs and manufactures military, commercial and experimental aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev started out as a research group to equip the Soviet military with metal-body aircraft. It produced over 18,000 planes for the USSR since its foundation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the end of the Cold War, Tupolev has done research on aircraft operations using alternative fuels.&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2015-09-04T14:25:08.257" LastActivityDate="2015-09-04T14:25:08.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20685" PostTypeId="4" CreationDate="2015-09-04T14:06:43.770" Score="0" Body="A Russian aerospace and defense company that designs and manufactures military, commercial and experimental aircraft." OwnerUserId="3775" LastEditorUserId="3775" LastEditDate="2015-09-04T14:24:56.787" LastActivityDate="2015-09-04T14:24:56.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20686" PostTypeId="2" ParentId="19443" CreationDate="2015-09-04T15:59:33.587" Score="9" Body="&lt;p&gt;&lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/managementservices-referencecentre-acs-300-300-004-1497.htm&quot; rel=&quot;noreferrer&quot;&gt;Advisory Circular (AC) 300-004&lt;/a&gt; from Transport Canada has detailed information regarding the maintenance of unpaved runways.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The purpose of this document is to outline methodologies for the&#xA;  measurement and reporting of surface shear strength for unpaved&#xA;  runways.  In addition, the document outlines recommended practices for&#xA;  condition inspection, maintenance and repair of airport gravel&#xA;  surfaces and turf landing strips.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Runways should be designed with consideration for drainage (slope, crown, etc), susceptibility to frost heave, vegetation, roughness, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintenance can be based on surface hardness measurements made with a &lt;em&gt;penetrometer&lt;/em&gt;. A schedule for periodic inspection is created when the runway is new. The AC recommends a maximum of three years between hardness measurements. One type of penetrometer measurement is described as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Boeing High Load Penetrometer (Reference Boeing Document No. D6-24555 - High Load Penetrometer Soil Strength Tester) consists of a hydraulic cylinder with a cone point test probe mounted at the rod end.  The hydraulic cylinder is normally positioned against the frame of a heavy vehicle which serves as a reactive load.  In the test procedure, the probe is driven at a steady rate to a 100 mm (4 inch) depth into the surface by the application of pressure through a hand pump.    Generally a pressure reading is taken about 30 seconds or less after movement of the penetrometer has stopped at the 100 mm (4 inch) depth.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Once maintenance is deemed to be required... &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Gravel pavement surface maintenance primarily involves periodic&#xA;  grading to remove the surface irregularities developing with time and&#xA;  to re-establish grades for drainage purposes. Occasionally, new gravel&#xA;  has to be added to replace lost material.  Dust suppression measures&#xA;  may also be needed during the summer months.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The recommended aggregate sizes are shown in this table from the AC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zf9VP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zf9VP.jpg&quot; alt=&quot;Gravel sizes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recommended grading method is shown here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BlIkU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BlIkU.jpg&quot; alt=&quot;Grading method&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note a wealth of information in the reference documents listed in section 2.1 of the AC.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.team-eagle.ca/wp-content/uploads/2012/10/CBR_Tech_Presentation_SWIFT_2012.pdf&quot; rel=&quot;noreferrer&quot;&gt;This presentation&lt;/a&gt; (.pdf link) from a company that provides airport maintenance services has additionl useful information and photos.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2015-09-04T18:42:57.637" LastActivityDate="2015-09-04T18:42:57.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20687" PostTypeId="2" ParentId="20682" CreationDate="2015-09-04T16:10:56.043" Score="2" Body="&lt;p&gt;The flight number is more readily available than the aircraft's registration number. With a simple call to the departure/arrival airport's information office (or even from the airport's website) anyone can get the flight number.&#xA;Sometimes the aircraft is not ready and another one is used for the scheduled flight so the registration number could be difficult to obtain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, a flight number uniquely identifies a route, a departure airport and time, a destination and an airline.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-09-04T16:10:56.043" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20688" PostTypeId="1" CreationDate="2015-09-04T19:55:33.343" Score="6" ViewCount="2330" Body="&lt;p&gt;I'm a student pilot. My homework this week is to plan a cross country flight from point A-&gt;B using dead reckoning and on the way back B-&gt;A using GPS and flight following.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, do I put on my NavLog the dead reckoning (course heading, estimate time established, estimated fuel burn, etc... for each leg) only for the A-&gt;B route? What do I put in for B-&gt;A (GPS flight). I assume: basic estimation of fuel burn for the whole flight, straight line distance; how about take off and top of climb, things like that...? How do you usually do this?&lt;/p&gt;&#xA;" OwnerUserId="9783" LastActivityDate="2015-09-07T21:04:58.107" Title="Cross Country Planning: What do I put in the NavLog for the GPS route?" Tags="&lt;flight-planning&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20689" PostTypeId="2" ParentId="20688" CreationDate="2015-09-04T20:23:13.867" Score="3" Body="&lt;p&gt;In the end of the day what you put on your flight log is your choice (although your particular instructor may require some things). You may want to elaborate a bit on your GPS course. Are you mapping point to point on the way back (flying directly from B-&gt;A or are you using GPS along with nav aids on the ground. For that matter what kind of GPS are you using, A handheld&gt; An in cockpit like a Garmin 430? iPad with Foreflight or the such?. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a big user of Foreflight and really like the moving maps it has but when flying VFR you should always have multiple ways of navigating ready should a give method cut out (like an iPad crash midflight etc). Lets say you are using the GPS to fly direct from B-&gt;A in that case you still know the distance and can calculate your fuel burn (climb out included). Since its point to point you are in theory flying a single heading the whole time. As such your log should have that single heading on it and you should be using your GPS to make sure you are maintaining your course. Keep in mind GPS will read out your ground track not the heading of the aircraft. In other words if you have a cross wind your compass/heading indicator will not be the same as your GPS track.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-04T20:23:13.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20691" PostTypeId="2" ParentId="20688" CreationDate="2015-09-04T21:38:34.617" Score="11" Body="&lt;p&gt;I can't tell you what specifically to include on your navlog (that's a judgement call you make as a pilot - you determine what has to go on the paper to satisfy yourself that you can complete the flight), but I can give you a crash course in my theory of navigation, and a practical example of how I decide what to put on my navlogs.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;What's the point of the Navlog?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At its core a navlog is a list of waypoints such that you could find your way from Point A to Point B via the listed route by using some navigational system.&lt;br&gt;&#xA;&lt;em&gt;Ideally&lt;/em&gt; the navlog should be usable with at least two independent navigational systems in case one breaks, and for a VFR flight one of those navigational systems should &lt;em&gt;always&lt;/em&gt; be &quot;Looking Out The Darn Window!&quot; (the window rarely breaks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For purposes of this discussion I'm going to focus on &lt;em&gt;waypoint selection&lt;/em&gt; and a few other housekeeping tasks. I'm ignoring stuff like calculating headings because while that stuff is important it's also just mechanical math: The waypoint selection requires you to exercise some judgment as a pilot.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;A Practical Example: KGON to KMGJ and back.&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;This is a nice 100 mile flight to use as an example. Let's plot the outbound trip using pilotage and dead reckoning, and the return trip using the GPS. (This is going to get photo-heavy, so I'm burying them in links.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing you do is &lt;a href=&quot;https://i.stack.imgur.com/2Q9Zn.jpg&quot; rel=&quot;noreferrer&quot;&gt;draw the straight line between the two airports on the chart&lt;/a&gt;. Then follow the line from Point A to Point B and mark off convenient landmarks. &lt;a href=&quot;https://i.stack.imgur.com/EuDDm.jpg&quot; rel=&quot;noreferrer&quot;&gt;I chose Chester Airport, the New Haven railroad/highway/river, abeam the Waterbury-Oxford Airport, the lake &amp;amp; prison north of Danbury (also abeam the Danbury airport), and the Hudson River (you can't miss it!).&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Pilotage Tip:&lt;/strong&gt; Airports (at least the larger ones) make great landmarks. They're also convenient landing places if you have a problem, so including them as waypoints is a double win.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Almost all of these legs can be completed by pilotage (you can always see the next waypoint/landmark), but one of the legs (Danbury to the Hudson) is about 24 nautical miles and on a hazy summer day you might not be able to see that far. You should therefore be prepared to fly at least this leg by dead reckoning (point the nose in the right general direction based on the heading you calculated, and fly until you see a big river).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navlog that Skyvector generates for this is &lt;a href=&quot;https://i.stack.imgur.com/k36rA.png&quot; rel=&quot;noreferrer&quot;&gt;somewhat unfriendly-looking, with lots of latitude/longitude fixes in it&lt;/a&gt;, and automatically generated ones from Foreflight and similar tools will look about the same. When you write up your navlog you can give each waypoint a descriptive name like I did above so you can remember what you're looking for in case your sectional blows out the window mid-flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So that takes care of the outbound trip with visual waypoints - what about the return trip using the GPS?&lt;br&gt;&#xA;GPS systems have convenient databases of airports, intersections, and navaids, so we draw the same straight line, then look at the chart and find the waypoints between our two airports that the GPS will know about. &lt;a href=&quot;https://i.stack.imgur.com/1VBHB.jpg&quot; rel=&quot;noreferrer&quot;&gt;The result looks like this&lt;/a&gt; and produces &lt;a href=&quot;https://i.stack.imgur.com/DscFq.png&quot; rel=&quot;noreferrer&quot;&gt;a navlog with nice waypoint names&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;GPS Tip:&lt;/strong&gt; I avoided using Lat/Long fixes in the GPS plan in favor of fixes that you can type in on any GPS, so this is fast and easy to enter on a Garmin 430/530 for example. Newer GPS systems like the touchscreen Garmins let you do &quot;rubber-band flight planning&quot; where you can drag your route of flight around and easily create waypoints wherever you want - you could even set up the same track I did for the outbound flight if you want.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Since you're flying under &lt;strong&gt;Visual&lt;/strong&gt; Flight Rules you're going to want to note down &lt;strong&gt;Visual&lt;/strong&gt; references to go with this navlog&lt;/em&gt; (because again if your instructor is anything like mine was your GPS is going to suddenly fail on the return trip while you're merrily following the magenta line).&lt;br&gt;&#xA;For this return trip the visual references would be Stewart Airport (and the Hudson River beyond it, even though it doesn't have a dot on this plan), the city of Brewster (which doesn't have a dot, but is identifiable as a city that has power lines, railroad tracks, and a highway immediately east of it), the Danbury airport (KDXR), abeam the Bridgeport airport (at TRUDE), and from there on you can cheat and use the shoreline (even if the entire electrical system died you can still find your way back to Groton by following the shore until you recognize &quot;home&quot;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;What about that other stuff? (Airspace, ToC/ToD, ETE, fuel burn, etc.)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are a few important things you don't get by picking out the waypoints the way I did it above.  The most obvious one is &lt;em&gt;Airspace&lt;/em&gt; -- you'll notice the course I've plotted cuts right through the Stewart (KSWF) Class D airspace, and Orange County is really close to the Class D ring. Unless you're in a helicopter there is no way you could fly above the Stewart airspace and then descend into Orange County along the plotted route without exceeding V&lt;sub&gt;NE&lt;/sub&gt;, so you're going to have to plan on talking to Stewart's tower and requesting a transition. Note the tower and ATIS frequencies and pick a spot along your course to call the tower up to request the transition. (Same goes for the return trip - we plan to cut through right over the airport so we need to call them and ask.)&#xA;Similarly you want to note the tower frequency of any airport you're passing so you can monitor it, and so you can call them up if something goes wrong. This information is on the chart, but printing it in big letters on your navlog makes it easier to find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Something else most flight instructors want to see you including are Top of Climb and Top of Descent (along with a calculation of fuel used in the climb or descent) - you get this the day of the flight by determining what altitude you want to climb to (based on the wind data you got in your pre-flight briefing) and referencing the aircraft's performance charts. You'll add a little mark to the course line on your chart for &lt;code&gt;TOC&lt;/code&gt; and &lt;code&gt;TOD&lt;/code&gt;, and I usually put it in a &quot;notes&quot; area on my navlog (&lt;code&gt;TOC xx minutes elapsed&lt;/code&gt; and if there's a convenient visual reference I note what it is).  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;General Tip:&lt;/strong&gt; I try to include some waypoint that will be at or near top-of-climb/top-of-descent on my flight plans - if you have a reasonable idea of how your plane performs you can usually pick something within a few miles for most reasonable wind conditions. Doing that makes it easier because I can use the time-fuel-distance charts in the POH to fill in the estimated time enroute to that waypoint (or waypoints if it's a long climb) and the fuel burn: One less thing to calculate.&lt;br&gt;&#xA;  I did not go out of my way to do this on the charts above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You should also be calculating an estimated time enroute between each waypoint based on your calculated groundspeed (again you'll work this out before you depart based on forecast winds - you'll see that Skyvector computed it for us based on a 100-knot airspeed and the wind data available as I was typing this).&lt;br&gt;&#xA;This seems a litle crazy for 10 to 30 mile legs like this (about 6 to 20 minutes enroute between each waypoint, but if we go back to the idea of using this navlog over a wide-open desert we may have an hour or more between waypoints, and cross-checking estimated time versus actual time lets you know if the winds are significantly different from the forecast values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The estimated time enroute in turn gives you your fuel burn for each leg: You know your engine burns a certain number of gallons per hour, and you know how many hours (or fractions of an hour) each leg will take - multiply to get your fuel burn.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Don't Run Out Of Gas Tip:&lt;/strong&gt; Plan conservatively: Round fuel consumption numbers up to the next half-gallon or gallon.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Finally every navlog has at least one other key element: &lt;em&gt;The heading you should be flying&lt;/em&gt;: &lt;code&gt;True Course ± Magnetic Variation ± Wind Correction Angle ± Compass Deviation = Magnetic Heading&lt;/code&gt; - What you steer on the compass. Skyvector calculated this for us (with the exception of the Compass Deviation which it can't know) but if you're doing the flight plan manually you need to do this math yourself.&lt;br&gt;&#xA;Again you would do this right before your flight, with the most current wind data.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-09-04T21:43:42.950" LastActivityDate="2015-09-04T21:43:42.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20692" PostTypeId="1" AcceptedAnswerId="20699" CreationDate="2015-09-04T22:48:26.750" Score="2" ViewCount="1826" Body="&lt;p&gt;Here is an example of a bypass ratio 9:6:1. 9kg goes around the core and 6kg goes into the core, but what is the 1 for.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-05T01:45:06.527" Title="What is this number in the bypass ratio?" Tags="&lt;bypass-ratio&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20693" PostTypeId="1" AcceptedAnswerId="20713" CreationDate="2015-09-04T23:03:12.160" Score="11" ViewCount="1372" Body="&lt;p&gt;For the pilot of a Cessna or Piper 4 seater, what techniques and other considerations should be given before operating on a gravel/dirt airstrip? &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="19" LastEditDate="2016-07-14T08:19:08.690" LastActivityDate="2016-07-14T08:19:08.690" Title="What considerations should be taken into account for landing on gravel airstrips?" Tags="&lt;landing&gt;&lt;flight-training&gt;&lt;general-aviation&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20694" PostTypeId="1" AcceptedAnswerId="20714" CreationDate="2015-09-04T23:16:46.850" Score="3" ViewCount="3567" Body="&lt;p&gt;How come, for example, the average cruising altitude of let's say the Westjet Boeing 737-600 from CYWG to CYVR flies at an altitude of 38,000 feet-40,000 feet, yet the Air Transat Airbus 330-200 flying from CYVR to Man EGCC flies between 33,000 feet and 35,000 feet?&#xA;Why is the air transat one flies lower when you'd think that with the Vancouver to Manchester route being more of a long-range flight than the Winnipeg to Vancouver one, it'd want to fly above the regional/domestic flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this so?&#xA;to illustrate, here are flightaware records for two recent flights: &#xA;Westjet: &lt;a href=&quot;https://flightaware.com/live/flight/WJA307/history/20150903/1210Z/CYWG/CYVR&quot; rel=&quot;nofollow&quot;&gt;https://flightaware.com/live/flight/WJA307/history/20150903/1210Z/CYWG/CYVR&lt;/a&gt;&#xA;Air Transat: &lt;a href=&quot;http://flightaware.com/live/flight/TSC284&quot; rel=&quot;nofollow&quot;&gt;http://flightaware.com/live/flight/TSC284&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="9281" LastEditorUserId="9731" LastEditDate="2015-09-05T03:11:48.353" LastActivityDate="2015-09-05T15:59:03.593" Title="why are regional cruising altitudes higher than those of international much longer flights?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20695" PostTypeId="2" ParentId="20692" CreationDate="2015-09-04T23:22:25.883" Score="10" Body="&lt;p&gt;It is &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx&quot;&gt;9.6:1&lt;/a&gt;  not 9:6:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;9.6 parts air are bypassed for each part that goes through the core.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-09-04T23:22:25.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20696" PostTypeId="1" AcceptedAnswerId="20704" CreationDate="2015-09-04T23:25:05.583" Score="4" ViewCount="5360" Body="&lt;p&gt;So I was doing some research on the Boeing 747-8/4 engines. I discovered that the PW4056/62 (747-400) has a much lower bypass ratio and weighs a lot less, and it is much smaller than the GEnx-2B67 (747-8). So it really seems the PW4084 is the more efficient engine. If it is not true than what improvements have been made on the  GEnx-2B67 to make it the more efficient engine? &lt;a href=&quot;https://i.stack.imgur.com/wLCKp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wLCKp.jpg&quot; alt=&quot;GEnx-2B67 engines on 747-8I&quot;&gt;&lt;/a&gt;GEnx-2B67 engines&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EsIBa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EsIBa.jpg&quot; alt=&quot;PW4084 engines on 747-400&quot;&gt;&lt;/a&gt;PW4056/62 engines&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-09-05T14:46:36.110" LastActivityDate="2019-10-02T18:53:05.277" Title="Are the Boeing 747-8 engines more efficient than the 747-400 engines?" Tags="&lt;boeing-747&gt;&lt;efficiency&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20697" PostTypeId="2" ParentId="20696" CreationDate="2015-09-05T00:03:31.350" Score="16" Body="&lt;p&gt;Yes. &lt;a href=&quot;http://www.geaviation.com/commercial/engines/genx/&quot; rel=&quot;noreferrer&quot;&gt;According to GE&lt;/a&gt;, the GEnx-2B consumes 15% less fuel than the CF6, which was contemporary to the PW4084 on the 747-400.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bypass ratio of a jet engine makes it &lt;a href=&quot;https://aviation.stackexchange.com/q/11586/1696&quot;&gt;more efficient, not less&lt;/a&gt;. A higher bypass ratio provides more thrust from the fan air, which means the core section can use less air and therefore less fuel to provide less thrust. This increase in efficiency is the reason turbojets evolved into turbofans and have been increasing in bypass ratio as technology improves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One consequence of a higher bypass ratio means the engine does get larger and heavier. However, the increase in efficiency is more than enough to offset these costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides increasing the bypass ratio, there have been many internal improvements in the GEnx line of engines, discussed in the GE link above. These changes include composite fan blades and fan case, which can be lighter than the metal alternatives. Throughout the engine there are also aerodynamic improvements to increase the efficiency of air flow through the engine, as well as more new materials and manufacturing technology.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-05T00:03:31.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20698" PostTypeId="2" ParentId="20694" CreationDate="2015-09-05T00:11:33.917" Score="11" Body="&lt;p&gt;Flight altitudes have relatively little to do with whether a flight is regional or international per se. More important factors include the winds aloft and the individual aircraft capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the Winnipeg to Manchester flight, they were probably using the North Atlantic Track System (NATS). The winds aloft over the North Atlantic are generally out of the west. The routes of the tracks are arranged each day to take advantage of the those winds. The track system puts the eastbound aircraft on tracks and at altitudes that would maximize the tailwinds, and westbound aircraft on tracks and at altitudes that minimize the headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the winds aloft in the northern hemisphere are more often than not westerly, the Winnipeg to Vancouver flight might well have been fighting a headwind, but the strongest winds aloft tend to occur in the mid 30s, which can mean that you can lessen the headwind by climbing higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft capability also plays a major role, and aircraft vary widely in what they can do altitude wise. For example, a 747-200 up against its max takeoff weight of 800,000+ lbs can initially climb to only about 31,000 feet (FL310), but towards the end of the flight can reach FL390 and above.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-09-05T00:11:33.917" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20699" PostTypeId="2" ParentId="20692" CreationDate="2015-09-05T01:45:06.527" Score="6" Body="&lt;p&gt;The bypass ratio of a turbofan engine is the ratio of the mass flow rate of the air that bypasses the engine core (i.e. it doesn't undergo combustion),$\dot{m_{f}}$ to the mass flow rate of the air that passes through the core $\dot{m_{c}}$ and undergoes combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bypass ratio is usually given as the mass flow of fan by the mass flow of core i.e. $\frac{\dot{m{f}}}{\dot{m_{c}}}:1$. In some cases, it is given as the ratio of cold air to hot air, $\frac{\dot{m{c}}}{\dot{m_{h}}}:1$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sJo5I.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sJo5I.gif&quot; alt=&quot;Bypass Ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, a bypass ratio of 9.6:1 means that 9.6 kg of air passes through the bypass fan for every 1 kg of air passing through the core.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-05T01:45:06.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20700" PostTypeId="1" AcceptedAnswerId="20702" CreationDate="2015-09-05T03:48:48.893" Score="11" ViewCount="1807" Body="&lt;p&gt;Forgive me if my question sounds more like a rule of engagement for aerial combat than aviation technique. I was wondering that is it ok, in a dogfight, for a victorious pilot to shoot a defeated pilot's parachute to kill him. Are there any records of this type of event?&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="1467" LastEditDate="2017-02-08T14:42:27.320" LastActivityDate="2017-02-08T14:42:27.320" Title="In a dogfight, can a pilot shoot down a parachute?" Tags="&lt;dogfighting&gt;&lt;fighter&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ClosedDate="2015-09-05T11:55:39.930" ContentLicense="CC BY-SA 3.0" />
  <row Id="20701" PostTypeId="2" ParentId="20693" CreationDate="2015-09-05T03:54:55.287" Score="-6" Body="&lt;p&gt;Gravel and dirt are two totally different things. Gravel can damage or ruin a propeller. With gravel you normally try to take off as gradually as possible, rather than ramp it up to full throttle immediately. Also, you do not do the run up on the gravel if at all possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With dirt or grass you do what are called soft field take offs and landings. This should have been covered in your instruction. If you have a pilot's license and do not know how to properly take off on a grass strip then something went wrong.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-09-05T03:54:55.287" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20702" PostTypeId="2" ParentId="20700" CreationDate="2015-09-05T04:01:00.803" Score="23" Body="&lt;p&gt;You question &lt;em&gt;is&lt;/em&gt; a question of rules of engagement. Shooting down a downed pilot in a dogfight is not only &lt;em&gt;not OK&lt;/em&gt;, but also &lt;em&gt;illegal&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.icrc.org/applic/ihl/ihl.nsf/Article.xsp?action=openDocument&amp;amp;documentId=0E0BF3B27E4F4E8EC12563CD0051DB78&quot;&gt;Article 42 of Geneva Conventions&lt;/a&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person parachuting from an aircraft in distress shall be made the object of attack during his descent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course, war is war and this kind of attacks &lt;a href=&quot;https://en.wikipedia.org/wiki/Attacks_on_parachutists&quot;&gt;have been practiced&lt;/a&gt; by pilots of almost all air forces, though it should be noted that in most cases, this practice was specifically prohibited by their high commands. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-05T04:01:00.803" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20703" PostTypeId="2" ParentId="19615" CreationDate="2015-09-05T04:18:04.070" Score="3" Body="&lt;p&gt;Yes, in the U.S. each metered airport (major airport) has what we call an AAR (Arrival Acceptance Rate) which varies sometimes hourly depending on weather and runways in use. One day the scheduled flights might get in with no delays, and the next many could be delayed by hours if the AAR goes down. This is managed by our flow control system which takes the current AAR for each airport and looks at pending departures for that airport and spaces out the departure times so that the AAR isn't exceeded. We call this the &quot;EDCT&quot; time (expected departure clearance time) and it shows up on the flight strip for ATC and is sent to the airline's dispatch office. A flight might be scheduled to depart at 12 noon, but their EDCT time might be 12:37 and they're supposed to plan their pushback and taxi so they're &quot;wheels up&quot; at that time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the standard AAR's at &lt;a href=&quot;http://www.fly.faa.gov/ois/&quot; rel=&quot;nofollow&quot;&gt;http://www.fly.faa.gov/ois/&lt;/a&gt; (click on east or west directory, then the appropriate Center and airport). LAX for example in VMC conditions using 25L/24L and R for approach has a 74 aircraft-per-hour AAR, but if it's foggy (low IMC) and they're using only 25L and 24R, the AAR drops to 58 per hour. If 70 are scheduled to arrive in some given hour, on a first-come-first-serve basis the computer will put out EDCT times to spread them out so only a max 58 will arrive in that hour, and the rest get bumped out to the next (and on and on). &lt;/p&gt;&#xA;" OwnerUserId="9957" LastActivityDate="2015-09-05T04:18:04.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20704" PostTypeId="2" ParentId="20696" CreationDate="2015-09-05T05:19:59.763" Score="16" Body="&lt;p&gt;In most of the engine performance parameters, the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GEnx&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE GEnx-2B67&lt;/a&gt; is a better and more efficient engine compared to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW4000&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney 4084&lt;/a&gt;. There are multiple reasons for this.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Fuel Consumption&lt;/strong&gt;: This is the parameter of the engine airlines are most interested in, as it affects their bottom lines. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thrust Specific fuel consumption&lt;/a&gt; gives the fuel consumed by the engine for unit thrust produced. In this case, the GEnx has over 20% improvement over the PW 4000 series (&lt;a href=&quot;http://adg.stanford.edu/aa241/propulsion/largefan.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.27&lt;/a&gt; versus &lt;a href=&quot;http://adg.stanford.edu/aa241/propulsion/sfc.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.348&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Bypass Ratio&lt;/strong&gt;: In general, a &lt;a href=&quot;https://aviation.stackexchange.com/questions/11586/what-is-a-high-bypass-geared-turbofan-and-why-is-it-so-much-more-efficient&quot;&gt;higher bypass ratio means a more efficient&lt;/a&gt; engine. The GEnx has a much better bypass ratio compared to the PW 4084 (8.6:1 versus 5.3:1).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Engine Noise&lt;/strong&gt;: The GEnx engines are specifically designed for reduced noise levels, incorporating the Chevrons.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Thrust to Weight Ratio&lt;/strong&gt;: This is a much better parameter compared to the weight alone for engine performance as the weight increases due to larger bypass fans, for example. In this case, both the engines have almost the same values (5.5 and 6).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Thrust&lt;/strong&gt;: Higher thrust means improved aircraft performance. The PW 4062 produces a maximum of 62,000lb thrust while the GEnx produces over 67,000 lbs of thrust.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;ETOPS&lt;/strong&gt;: Another advantage of GEnx engine is that it is certified for Extended-range Twin-engine Operational Performance Standards (ETOPS), (in Boeing 747-8) which indicates that the reliability of engine is high. The PW 4062 engines used in 747-400 does not have this certification (Engine is only a part, albeit important of ETOPS certification though)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The engine used in the 747-400 is the PW 4056 and 4062. PW 4084 is used exclusively in Boeing 777.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="11215" LastEditDate="2019-10-02T18:53:05.277" LastActivityDate="2019-10-02T18:53:05.277" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="20706" PostTypeId="1" AcceptedAnswerId="20707" CreationDate="2015-09-05T06:50:22.273" Score="12" ViewCount="1029" Body="&lt;p&gt;Is there a switch on the instrument panel that will set the thrust reversers to activate on touchdown like the autobrake? Or is using the thrust levers the only way to activate them?&lt;/p&gt;&#xA;" OwnerUserId="9173" LastEditorUserId="9173" LastEditDate="2015-09-05T07:38:51.457" LastActivityDate="2015-09-06T02:32:49.200" Title="Can thrust reversers be set to automatically activate on touchdown?" Tags="&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20707" PostTypeId="2" ParentId="20706" CreationDate="2015-09-05T09:10:52.510" Score="14" Body="&lt;p&gt;&lt;em&gt;Can&lt;/em&gt; it be done? Yes. &lt;em&gt;Is&lt;/em&gt; it done? No. The consequences of unintended operations are serious.&#xA;To the best of my knowledge, &lt;em&gt;no&lt;/em&gt; aircraft has the option set automatic thrust reverser. Using the levers are the only way to operate them. In fact, most of the design efforts have gone the other way- to ensure that thrust reversers are not deployed inadvertently.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In most aircraft, the Reverse Thrust Levers can be raised only when the Forward Thrust Levers are in the idle position. The thrust reversers have separate levers in front of the engine controls, which are prevented mechanically from operating otherwise.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xhDtg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xhDtg.jpg&quot; alt=&quot;Boeing 787 Thrust reversers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: bloginblack.de&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There are sensors installed in the engines which auto-stow the thrust reversers in flight.&lt;/li&gt;&#xA;&lt;li&gt;The design philosophy of thrust reversers is that it is better to not deploy them when needed rather than deploy them when not needed i.e. they are designed to fail.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main reason for such a design philosophy is safety. Any uncommanded deployment of thrust reversers in any phase of flight can have serious consequences.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Takeoff- If the trust reversers are deployed in one engine before $V_{1}$, the aircraft will veer off the runway. If it is deployed after $V_{1}$ and before $V_{2}$,the aircraft cannot achieve $V_{r}$ required to initiate rotation.&lt;/li&gt;&#xA;&lt;li&gt;Flight- Deployment of thrust reversers during flight can lead to &lt;a href=&quot;https://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow noreferrer&quot;&gt;controllability issues&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Landing- Deployment of thrust reversers during landing &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_India_Express_Flight_812&quot; rel=&quot;nofollow noreferrer&quot;&gt;practically eliminates&lt;/a&gt; the option of rejected landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Because of these reasons and reliability issues with thrust reversers, there is no option for automatic deployment of thrust reversers.  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-06T02:32:49.200" LastActivityDate="2015-09-06T02:32:49.200" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20709" PostTypeId="2" ParentId="17015" CreationDate="2015-09-05T11:57:10.773" Score="0" Body="&lt;p&gt;An annex is quite literary what it says.  It is a document that is annexed (or &quot;appended' or &quot;attached&quot;) to the ICAO convention (where &quot;convention&quot; means a document). An &quot;annex&quot; states the Standards and Recommend practices (SARPs) expected from State signatories to the ICAO convention. The documents expand on the SARPS explaining and/or nominating how and what a State  has to do to achieve the SARPs. In essence in simplistic terms an annex is the chapter heading of a book and the documents are the content of the chapter.&lt;/p&gt;&#xA;" OwnerUserId="11104" LastActivityDate="2015-09-05T11:57:10.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20710" PostTypeId="2" ParentId="19636" CreationDate="2015-09-05T15:04:34.997" Score="3" Body="&lt;p&gt;Having spent a lot of time on flight simulator, and having done an intro lesson, is a big factor in your favor, because you know how to steer, ascend, descend, and &lt;em&gt;especially&lt;/em&gt; trim for speed. What you may not know is how to work the radio, how to tune to 121.5 and how to press the talk button (and most importantly, release it). Then the only other thing that might be new to you is landing. So if they guide you to a long, wide strip, aligned with the wind, all you have to do is &quot;ride the slide&quot;, and pull the throttle when you get to the ground.&lt;/p&gt;&#xA;" OwnerUserId="395" LastActivityDate="2015-09-05T15:04:34.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20711" PostTypeId="2" ParentId="9323" CreationDate="2015-09-05T15:30:43.673" Score="2" Body="&lt;p&gt;If your aircraft is certified under Part 23 as opposed to CAR3, it would be obligated to abide by the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;§23.1441   Oxygen equipment and supply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(a) If certification with supplemental oxygen equipment is requested, or the airplane is approved for operations at or above altitudes where oxygen is required to be used by the operating rules, oxygen equipment must be provided that meets the requirements of this section and §§23.1443 through 23.1449. &lt;strong&gt;Portable oxygen equipment may be used&lt;/strong&gt; to meet the requirements of this part if the portable equipment is shown to comply with the applicable requirements, &lt;strong&gt;is identified in the airplane type design,&lt;/strong&gt; and its stowage provisions are found to be in compliance with the requirements of §23.561&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I added the boldness to the text.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what portable oxygen is identified in an aircraft's type design? What is a &quot;type design&quot; anyway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One &lt;a href=&quot;http://aviationglossary.com/type-design/&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt; says Type design is this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) The drawings and specifications, and a listing of those drawings and specifications, necessary to define the configuration and the design features of the product shown to comply with the requirements applicable to the product; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Information on dimensions, materials, and processes necessary to define the structural strength of the product; and &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) The Airworthiness Limitations section of the ICA as required by Parts 23, 25, 27, 29, 33, and 35, or as otherwise required by the Administrator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do you get from needing it to be &lt;strong&gt;identified in the type design&lt;/strong&gt; to its ok to use it? Unless you find where it is identified... you can't connect them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But CAR3 was more lenient on this and portable oxygen systems do not violate it. I find no mention of Oxygen requirements in CAR3.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-09-05T15:30:43.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20712" PostTypeId="1" CreationDate="2015-09-05T15:35:17.470" Score="7" ViewCount="254" Body="&lt;p&gt;It seems with electric control of the multi engine configuration, such as with NASA's new leap tech technology, that there should be a way to use multiple motors in the LSA category. Is there anything in the works regarding regulations for this type of aircraft in the LSA category?&lt;/p&gt;&#xA;" OwnerUserId="3366" LastActivityDate="2020-01-22T06:01:45.227" Title="Are there any future regulations planned for electric multi-motor LSAs?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;light-sport-aircraft&gt;&lt;electric-engine&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20713" PostTypeId="2" ParentId="20693" CreationDate="2015-09-05T15:57:50.407" Score="8" Body="&lt;p&gt;Standard soft-field landing and take-off techniques work on dirt, gravel or grass. The differences are more in ground operations, and even then they aren't really big differences: it comes down to being aware of what's around you and what condition the surface is in. That includes taxi and parking areas, not just the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With gravel, the main risk is damage to the aircraft (especially the prop) or nearby people, vehicles or objects caused by gravel being thrown up by the prop. With dirt, you're more likely to have to worry about drag or even getting stuck, especially if the surface is wet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some specific considerations for gravel are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you're parked on gravel, be careful where the aircraft is pointed when you start up. You don't want to spray some unfortunate person, vehicle or building behind you. Re-position the aircraft before starting up if you have to, and you could also brush gravel away from the prop.&lt;/li&gt;&#xA;&lt;li&gt;For the same reason, pick your runup spot carefully&lt;/li&gt;&#xA;&lt;li&gt;Keep back pressure on the controls all the time while taxiing, to keep the prop as far away from the surface as possible. Don't feel you have to taxi in a straight line: taxi wherever the gravel is lightest and the surface is smoothest.&lt;/li&gt;&#xA;&lt;li&gt;Open the throttle smoothly for takeoff or runups to avoid suddenly throwing up gravel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Dry, well-packed dirt usually isn't much of an issue (apart from visibility), but wet dirt - i.e. mud - is potentially tricky:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If conditions are very dry then you can throw up a lot of dust. That may not be as dangerous as spraying gravel around, but it's still unpleasant for anyone nearby and there is a safety risk if people can't see you or other aircraft/vehicles because of it.&lt;/li&gt;&#xA;&lt;li&gt;If conditions are wet then there's a risk of getting stuck in mud. Once you're moving, try not to stop unless absolutely necessary. Consider doing a 'rolling runup' if you're confident you can do it safely (practice on tarmac first!).&lt;/li&gt;&#xA;&lt;li&gt;Calculate your required takeoff roll carefully and know exactly where you have to abort. Mud will create a lot of drag, and you don't want to push your luck on what is most likely a short runway.&lt;/li&gt;&#xA;&lt;li&gt;If you take off from wet dirt you'll leave ruts behind you. When the dirt dries out those will still be there, and they could be a hazard to other aircraft using the runway (some dirt becomes very hard when it dries). Try to find someone who can smooth them out after you depart.&lt;/li&gt;&#xA;&lt;li&gt;If you do get mud on your aircraft, clean it off if at all possible before taking off. As well as decreasing performance, it could clog up pitot-static ports or otherwise affect airworthiness.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-09-08T15:16:24.273" LastActivityDate="2015-09-08T15:16:24.273" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20714" PostTypeId="2" ParentId="20694" CreationDate="2015-09-05T15:59:03.593" Score="8" Body="&lt;p&gt;It seems you looked at flights which had begun shortly before. Since intercontinental flights require a higher &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_fraction&quot; rel=&quot;nofollow noreferrer&quot;&gt;fuel fraction&lt;/a&gt; to carry enough fuel for the trip, the airplane cannot climb as high initially as one with little fuel onboard. Note that the maximum range of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 737-700 is 6230&amp;nbsp;km&lt;/a&gt;, while the flight you chose to take as the basis for your question covered only 1936&amp;nbsp;km. The tanks were probably less than half full, and depending on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Passenger_load_factor&quot; rel=&quot;nofollow noreferrer&quot;&gt;passenger load factor&lt;/a&gt;, the airplane was probably well below its maximum take-off mass, hence it had &lt;a href=&quot;https://aviation.stackexchange.com/questions/12541/why-are-many-jet-aircraft-designed-to-cruise-around-fl350-370/12569#12569&quot;&gt;no problem to climb so high&lt;/a&gt; early in the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Had you included intercontinental flights close to their destination, your question would had been different. Note that TSC284 flew in &lt;a href=&quot;http://de.flightaware.com/live/flight/TSC284/history/20150904/0020Z/CYVR/EGCC/tracklog&quot; rel=&quot;nofollow noreferrer&quot;&gt;FL390&lt;/a&gt; shortly before descending. At this point, the tanks held only a fraction of the fuel at take-off, and for a flight of 7526&amp;nbsp;km it had probably taken off close to its maximum take-off mass. The fuel load of long-range aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330&quot; rel=&quot;nofollow noreferrer&quot;&gt;A330-200&lt;/a&gt; can be more than 40% of the take-off mass, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/8652/how-can-i-calculate-the-fuel-consumption-of-an-airbus-320-200-at-various-loads/8654#8654&quot;&gt;using up most of the initial fuel load&lt;/a&gt; can make a lot of difference in the maximum possible flight altitude.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-09-05T15:59:03.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20715" PostTypeId="1" AcceptedAnswerId="20740" CreationDate="2015-09-05T20:11:41.343" Score="3" ViewCount="1085" Body="&lt;p&gt;I had assumed that all flights between western Europe and North America would use the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot; rel=&quot;nofollow noreferrer&quot;&gt;North Atlantic Tracks&lt;/a&gt; (NATs) but &lt;a href=&quot;https://aviation.stackexchange.com/a/8278/946&quot;&gt;this answer&lt;/a&gt; says that, actually, only about half do.  What reasons might a flight have for not using the tracks?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia says that Concorde didn't use the tracks because it flew above them but I'd expect all commercial transatlantic flights these days to be within the band covered by the tracks (FL290&amp;ndash;410).&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2017-05-18T14:17:41.850" Title="Why don't all flights use the North Atlantic Tracks (NATs)?" Tags="&lt;navigation&gt;&lt;oceanic&gt;&lt;transatlantic&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20716" PostTypeId="1" CreationDate="2015-09-05T20:58:51.463" Score="5" ViewCount="202" Body="&lt;p&gt;This question might be a little bit off-topic, but I'll give a try.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Me and many people are aeronautics &quot;aficionados&quot; that would love to know about flying data during flight. Today we all have smartphones that run apps for everything: why couldn't airplanes have an internal WIFI for &lt;strong&gt;only&lt;/strong&gt; broadcasting flight data for being displayed in our smartphones (i.e. as if they were cockpit simulators) as well as video streaming from external cameras? Of course this kind of internal network's purpose would be to broadcast data, so security wouldn't be an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anybody know if aircraft manufacturers plan to develop such kind of project?&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="1696" LastEditDate="2015-09-06T00:22:29.677" LastActivityDate="2015-09-07T00:28:49.653" Title="Is there any plan to make flights more interactive using smartphones?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20717" PostTypeId="1" CreationDate="2015-09-05T21:16:23.340" Score="1" ViewCount="100" Body="&lt;p&gt;Since thrust reversers take time to deploy and stow are you committed to the landing once you engage them?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-09-05T21:16:23.340" Title="Is it possible to reject a landing after the thrust reversers have been deployed?" Tags="&lt;landing&gt;&lt;thrust-reverser&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-09-05T21:57:58.717" ContentLicense="CC BY-SA 3.0" />
  <row Id="20718" PostTypeId="1" CreationDate="2015-09-05T21:18:11.973" Score="16" ViewCount="1418" Body="&lt;p&gt;This aircraft is sitting at YCW, with no visible registration numbers.  Can you identify it? &lt;a href=&quot;https://i.stack.imgur.com/Whetj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Whetj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11106" LastEditorUserId="19" LastEditDate="2016-07-06T08:47:20.940" LastActivityDate="2016-07-06T08:47:20.940" Title="Can you identify this aircraft at Chilliwack(YCW)?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20719" PostTypeId="2" ParentId="20718" CreationDate="2015-09-05T21:24:46.050" Score="30" Body="&lt;p&gt;It's a &lt;a href=&quot;http://jetphotos.net/showphotos.php?regsearch=N4913V&quot;&gt;De Havilland DH104 Dove&lt;/a&gt;. It did have a registration of &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?nNumberTxt=N4913V&quot;&gt;N4913V&lt;/a&gt; but it was cancelled in 2012.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Dove&quot;&gt;The Dove&lt;/a&gt; is an airliner that can seat 8 passengers, and 542 were produced from 1946 to 1967.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-09-05T21:24:46.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20720" PostTypeId="2" ParentId="847" CreationDate="2015-09-05T23:58:19.420" Score="8" Body="&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/gNbDY.jpg&quot; alt=&quot;Evektor SportStar MAX is optionally IFR equipped&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry to reanimate this rather old question, but I'm surprised none of the previous answers mentioned the Evector SportStar MAX, which has a model that is IFR equipped and which was available several years before this question was asked. From its POH (section 1.2):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Certification basis&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;SportStar MAX complies with the ASTM F2245-07a Standard Specification for Design and Performance of a Light Sport Airplane, issued by ASTM International Committee F37.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;IFR version complies with FAR 91.205 requirements, ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here's a &lt;a href=&quot;http://www.planeandpilotmag.com/aircraft/pilot-reports/evektor/evektor-sportstar-max-an-lsa-for-all-seasons.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Plane &amp;amp; Pilot&lt;/em&gt; review&lt;/a&gt; of the IFR version, and here's a &lt;a href=&quot;http://www.businesswire.com/news/home/20090616006250/en/Evektor-Aircraft-Announces-Major-Flight-School-Incentive&quot; rel=&quot;noreferrer&quot;&gt;Press Release from Evector&lt;/a&gt; about this model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Evektor followed the MAX model with the Harmony, and at least one place on their website suggests it too is available in an IFR equipped version.&lt;/p&gt;&#xA;" OwnerUserId="11107" LastEditorUserId="11107" LastEditDate="2015-09-06T00:05:16.453" LastActivityDate="2015-09-06T00:05:16.453" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20721" PostTypeId="2" ParentId="20716" CreationDate="2015-09-05T23:59:32.377" Score="7" Body="&lt;p&gt;Actually some airline did it already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many Airways including &lt;a href=&quot;http://www.qantas.com.au/travel/airlines/wireless-inflight-entertainment/au/en&quot; rel=&quot;nofollow&quot;&gt;Qantas&lt;/a&gt;, &lt;a href=&quot;http://crankyflier.com/2011/09/19/virgin-americas-wireless-inflight-entertainment-isnt-quite-what-you-might-think/&quot; rel=&quot;nofollow&quot;&gt;Virgin American&lt;/a&gt;, &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/onboard-experience/entertainment/delta-studio.html&quot; rel=&quot;nofollow&quot;&gt;Delta&lt;/a&gt;, &lt;a href=&quot;http://www.lhsystems.com/solutions-services/inflight-entertainment/boardconnect.html&quot; rel=&quot;nofollow&quot;&gt;Lufthansa&lt;/a&gt; and &lt;a href=&quot;http://www.dragonair.com/ka/en_HK/travel-information/inflight/entertainment/wireless-inflight-entertainment-system.html&quot; rel=&quot;nofollow&quot;&gt;DragonAir&lt;/a&gt; (but Cathay not) has installed Wireless inflight entertainment system which allows passengers to access entertainment system and track flight via their mobile/tablet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surprisingly some LCC like &lt;a href=&quot;http://www.virginaustralia.com/au/en/experience/on-board-the-flight/in-flight-entertainment/wireless/&quot; rel=&quot;nofollow&quot;&gt;Virgin Australia&lt;/a&gt; and &lt;a href=&quot;https://www.southwest.com/html/air/products/wifi-access.html?clk=GFOOTER-PRODUCTS-WIFI&quot; rel=&quot;nofollow&quot;&gt;Southwest&lt;/a&gt; also provides wireless on-flight entertainment system, though some contents is not free of charge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, several airline use Tablet to replace the original inflight entertainment system in upper class like &lt;a href=&quot;http://www.celebrityradio.biz/review-la-compagnie-airlines-paris-london-new-york/&quot; rel=&quot;nofollow&quot;&gt;La Compagnie&lt;/a&gt; (All business class airline), as well as some paid onboard entertainment services in LCC.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-09-07T00:28:49.653" LastActivityDate="2015-09-07T00:28:49.653" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20722" PostTypeId="1" CreationDate="2015-09-06T02:14:21.313" Score="8" ViewCount="1090" Body="&lt;p&gt;In the USA, a pilot can obtain an &lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v05%20airman%20cert/chapter%2009/05_009_002rev1.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;AEA (authorized experimental aircraft) rating to fly demilled surplus military turbojet-powered aircraft under FAA 5-1580(A)&lt;/a&gt;.  Part of its requirements are to have logged a minimum of 1,000 hours pilot flight time, including 500 hours as pilot in charge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8966/is-it-possible-to-log-ifr-currency-in-a-flight-simulator-without-an-instructor&quot;&gt;A student pilot can NOT log hours in a FAA-aproved AATD or BATD simulator, unless an instructor is present.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, AFTER someone has their private pilot's license, are they then able to log some hours in an FAA-approved AATD or BATD solo (without instructor) toward their 1,000 and/or 500 hours required for the experimental rating?  (Perhaps even using a simulation of the surplus military aircraft they want to have authorization for?)  Or, is that level of distrust from un-verifiability still there after someone has their private pilot's license?&lt;/p&gt;&#xA;" OwnerUserId="10052" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-11-03T18:51:54.037" Title="Does FAA simulator (AATD/BATD) count toward experimental rating 1,000 hours requirement?" Tags="&lt;flight-training&gt;&lt;usa&gt;&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20723" PostTypeId="2" ParentId="20716" CreationDate="2015-09-06T02:22:11.493" Score="5" Body="&lt;p&gt;Many airlines have done this already.  It's much cheaper for the airline to provide a wifi network within the airplane that passenger devices can use than to run a screen and the corresponding hardware to each seat.  The screens and all the cabling required to make them work have a significant cost in weight, space, maintenance, and complexity -- all things which airlines hate because it costs them money.  A wifi access point capable enough to stream video to a couple hundred devices and a small server with enough storage to store music and TV programs and movies can probably be done with less than 20 kilos of additional weight, so this is a big gain for the airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you combine that with either a satellite or a terrestrial receiver for internet type data, you have a relatively complete system for people to use smartphones, tablets, computers, etc.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much the airlines charge for this, or whether they offer some of the services for free becomes more of a business / pricing decision than a technical one.  For any local (meaning &quot;stored on the airplane&quot;) content, the onboard wifi is more than enough bandwidth for the users.  For anything that has to communicate via the satellite or terrestrial data link, the cost to the airline will almost always be high enough that they will want to pass those costs on to the passengers.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of this writing (Sept 2015) I've been on a number of United Airlines flights where the local cached content (streaming movies and TV shows) are free for people to use, and you can also get to a selected set of webpages which are locally generated and show things like the aircraft location, the ground speed, the estimated time of arrival, etc.&lt;/p&gt;&#xA;" OwnerUserId="8031" LastActivityDate="2015-09-06T02:22:11.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20724" PostTypeId="2" ParentId="1436" CreationDate="2015-09-06T03:33:38.890" Score="2" Body="&lt;p&gt;The confusing ones are twin-engined, wide or narrow bodied. &#xA;Narrow body, (single-aisle): 737, A-320, 757, (Also Embraier Em-170...195, Sukhoi 100, Bombardier C class, Tu-204..)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Nose shape is useful. Boeings tend to be more pointed, as shown above.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airbus had little 'winglets' that go both above and below the wing on their older products. Boeing winglets are much taller, with curved transitions from wing to winglet. The latest 737 options are double-diagonal winglets that extend above and below the wing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;737s have very short main landing gear, so their engines are mostly ahead of the wing. Their main gear have 2 wheels (as shown above) and the outside of the outer wheel and tire are visible from below, no doors over them. Lots were built without winglets, but retrofits and new airplanes have tall winglets that curve up above the wing. The latest 737 winglets are inclinded, above and below the wing, like half an &quot;X&quot;.&#xA;Exclusive operators include Southwest (USA) and Ryan Air (Ireland). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A-318, A-319, A-320, A-321, are different lengths, short to long, narrow bodied, similar in size to the 737 family, but have longer landing gear legs, and their engines are under their wings. Almost all built with with small, flat, winglets, above and below the wings. Exclusive operators include Jet Blue, Virgin America&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;757 family are narrow-bodied twin engined, with unusual cockpits. They share the cockpit design of the wide-body 767, higher numbered but designed earlier. 757s have deeper fuselages aft of the wing than in front of the wing. Many are being retrofitted with large winglets.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Wide body, (double-aisle): A-300, A-310, A-330, 767, 777, 787.&#xA;more later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Three or four engine airplanes are really pretty easy:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A-380s, with two decks, full length, are Airbus products.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;747s, with small to medium upper decks behind the cockpit, are Boeings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;727s, with three skinny, low-bypass, engines, are Boeings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tu-134 and 154 are three-skinny-engined, narrow bodied, with distinctive fairings on the trailing edge of the wings into which the main landing gear retract.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;DC-10 / MD-10 / MD-11 Are wide-bodied, have high-bypass engines, with the middle one mounted in the middle of the vertical fin/rudder. FedEx operate them, but not exclusively. The USAF use some as tankers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;L-1011 are wide bodied, have high bypass engines, with the middle one mounted inside the back of the fuselage, like a 727, Tu-154, etc. Orbital Sciences operate one as a carrier for satellite launches. The RAF used some as tankers, nearly all are retired now.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="1897" LastEditDate="2015-09-06T03:40:34.833" LastActivityDate="2015-09-06T03:40:34.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20725" PostTypeId="1" AcceptedAnswerId="20728" CreationDate="2015-09-06T06:49:37.517" Score="16" ViewCount="28372" Body="&lt;p&gt;Just seen a C17 Globemaster painted in civilian Qatar Airlines livery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sFLpL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sFLpL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea for the reason? Is this aircraft for civilian or a military use?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="167" LastEditDate="2015-09-07T03:13:39.887" LastActivityDate="2019-06-14T03:22:09.333" Title="Why would a C-17 Globemaster be painted in Qatar Airways livery?" Tags="&lt;plane-spotting&gt;&lt;livery&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20726" PostTypeId="2" ParentId="20725" CreationDate="2015-09-06T06:59:37.137" Score="9" Body="&lt;p&gt;It is for military use. As you can see from your photo, the registration code is &amp;quot;MAB&amp;quot; and this site links that aircraft to the &lt;a href=&quot;http://www.planespotters.net/Airline/Qatar-Emiri-Air-Force&quot; rel=&quot;noreferrer&quot;&gt;Qatar Emiri Air Force&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Current fleet:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A7-MAA&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;A7-MAB&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;A7-MAC&lt;/li&gt;&#xA;&lt;li&gt;A7-MAE&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-06T06:59:37.137" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20727" PostTypeId="1" CreationDate="2015-09-06T15:26:56.270" Score="26" ViewCount="8530" Body="&lt;p&gt;I have watched Live ATC tons of time. But I still don't know which airline is called &quot;Top 1%&quot;. Ex: Delta 81 right Bravo right Kilo give way to company A380 and follow the Top 1%&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just wanna know what &quot;Top 1%&quot; means. Or that is only for JFK?&lt;/p&gt;&#xA;" OwnerUserId="11112" LastEditorUserId="62" LastEditDate="2015-09-06T23:25:55.550" LastActivityDate="2018-08-31T01:08:52.137" Title="What does Top 1% mentioned by ATC refer to?" Tags="&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20728" PostTypeId="2" ParentId="20725" CreationDate="2015-09-06T15:28:34.860" Score="15" Body="&lt;p&gt;It is a military C-17 of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Qatar_Air_Force&quot; rel=&quot;noreferrer&quot;&gt;Qatar Air Force&lt;/a&gt;, one of the four in operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is in this livery as it is being operated by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Qatar_Amiri_Flight&quot; rel=&quot;noreferrer&quot;&gt;Qatar Amiri Flight&lt;/a&gt;, a VIP airline owned and operated by the government of Qatar. The vast majority of the Qatar Amiri Flight fleet is painted in the standard livery of Qatar Airways, like this A340 below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E3dsZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E3dsZ.jpg&quot; alt=&quot;Airbus A340&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is only operated by the Qatar Amiri Flight, not owned by it. The picture below shows the Qatar Air Force roundel on the underside of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wH6Ra.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wH6Ra.jpg&quot; alt=&quot;C 17&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.youtube.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-06T15:52:31.753" LastActivityDate="2015-09-06T15:52:31.753" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20729" PostTypeId="2" ParentId="19636" CreationDate="2015-09-06T15:58:13.777" Score="8" Body="&lt;p&gt;Step 1 not mentioned so far: keep the unconscious pilot from slumping forward into the controls.  Their body pushing the yoke in would be a bad thing at this juncture.  Cinch up on the shoulder harness and hang the flight bag strap or something similar on the pilot's forehead, with the bag hanging behind the seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then do all the other things in the excellent answers here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many years ago I had my wife take a one-day course on exactly this scenario, called the Non-Pilot Pinch Hitters course.  I don't know if it's still offered anywhere, but I found that AOPA has a &lt;a href=&quot;http://flash.aopa.org/asf/pinch_hitter/swf/flash.cfm?keycode=FX07CRS&amp;amp;offercode=FX07CRS&quot; rel=&quot;noreferrer&quot;&gt;flash version online&lt;/a&gt;.  It is most important to familiarize your flying companion ahead of time (assuming it's not a dog) with the radio and how to keep the wings level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the checklist from the AOPA course:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7J3vx.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7J3vx.png&quot; alt=&quot;pinch hitter checklist&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="554" LastEditorUserId="554" LastEditDate="2015-09-06T18:31:59.143" LastActivityDate="2015-09-06T18:31:59.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20730" PostTypeId="1" AcceptedAnswerId="20738" CreationDate="2015-09-06T17:48:34.187" Score="7" ViewCount="374" Body="&lt;p&gt;Lets say that you were in a floatplane (whether it be Terry's floating Cub or a big ol' Martin Mars) and the only otherwise-reasonably-suitable landing spot in the waterway where you are trying to go, or the taxi route from your landing site to your destination dock for that matter, is crossed by a movable bridge (aka drawbridge) that will not clear your aircraft when the drawspan is closed.  How would you, the floatplane pilot, signal the bridgekeeper to open the bridge so you can land/taxi through the navigable channel provided, especially considering you don't have a foghorn to signal the keeper with, and the keeper only has a marine VHF radio, which you may not have?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume that the drawspan can clear your plane when open (always true for bascule and swing spans; landing under a liftspan would be rather challenging though), and that the bridge is operated by a local bridgetender 24/7 (lesser-used drawspans often require prior notice, and there are also remote-control drawbridges out there that use sensors and/or CCTV to indicate the presence of marine traffic to a bridge operator sitting far away).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-09-06T18:47:14.040" LastActivityDate="2017-07-29T11:38:35.717" Title="Operating a floatplane/seaplane on water through a drawspan?" Tags="&lt;landing&gt;&lt;taxiing&gt;&lt;seaplane&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20731" PostTypeId="2" ParentId="20727" CreationDate="2015-09-06T18:23:52.013" Score="36" Body="&lt;p&gt;I'm guessing you're referring to a clip such as &lt;a href=&quot;https://youtu.be/JNUL-jX8IeE?t=1m46s&quot;&gt;this one&lt;/a&gt;. JFK ground is just being a bit informal and fun (as you can tell from the rest of the clip) with their instructions. Although it isn't mentioned, the controller is probably referring to a business jet flight, such as &lt;a href=&quot;http://flightaware.com/live/fleet/EJA&quot;&gt;ExecJet&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;top 1%&quot; refers to a ranking based on income, specifically those not in &lt;a href=&quot;https://en.wikipedia.org/wiki/We_are_the_99%25&quot;&gt;the lower 99%&lt;/a&gt;. The controller is basically telling them to follow the rich people in their fancy private jet. JustSid found &lt;a href=&quot;https://youtu.be/_0qLshYMKys?t=1m25s&quot;&gt;another video&lt;/a&gt; where the controller explains it as &quot;someone richer than both you and me.&quot;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-09-06T22:42:23.677" LastActivityDate="2015-09-06T22:42:23.677" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20733" PostTypeId="1" CreationDate="2015-09-06T21:05:51.050" Score="6" ViewCount="9669" Body="&lt;p&gt;In my understanding turbofan engines usually have 2 stages of compressors:    &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;one low pressure compressor    &lt;/li&gt;&#xA;&lt;li&gt;followed by a high pressure compressor&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But it looks like the high pressure compressor cancels the job done by the low pressure compressor, doesn't it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the point of decreasing pressure in the first compressor if you then increase it in the second compressor?  Why not using only the high pressure compressor?&lt;/p&gt;&#xA;" OwnerUserId="11114" LastEditorUserId="330" LastEditDate="2015-09-07T12:23:37.550" LastActivityDate="2019-03-25T22:59:06.193" Title="Why do turbofan engines have low pressure compressors?" Tags="&lt;turbofan&gt;&lt;compressor&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20734" PostTypeId="2" ParentId="20733" CreationDate="2015-09-06T21:10:37.643" Score="10" Body="&lt;p&gt;The low pressure compressor does &lt;strong&gt;not&lt;/strong&gt; reduce pressure. It increases it, but operates at a lower pressure than the high pressure compressor.  Some engines also have an intermediate pressure (IP) stage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_turbine_engine_compressors&quot;&gt;https://en.wikipedia.org/wiki/Gas_turbine_engine_compressors&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/compress.html&quot;&gt;https://www.grc.nasa.gov/www/k-12/airplane/compress.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each stage increases the pressure as the air is forced back into the flame tubes.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-07T06:33:16.190" LastActivityDate="2015-09-07T06:33:16.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20735" PostTypeId="1" CreationDate="2015-09-06T21:41:26.020" Score="4" ViewCount="657" Body="&lt;p&gt;From my brief Wikipedying, if &lt;a href=&quot;https://en.wikipedia.org/wiki/Counter-rotating_propellers&quot; rel=&quot;nofollow&quot;&gt;counter-rotating props' tops go towards each other, each has a reduced P-factor&lt;/a&gt; so the loss of either engine won't yaw the aircraft as hard as if the bottoms come together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I don't really care about safety of my aircraft's occupants (usually a couple ants after it sits on the grass) or reliability, I'd prefer to &lt;em&gt;increase&lt;/em&gt; the P-factor for fun and flat spin potential. Out of curiosity, does the direction of counter-rotating props (rather, counter- or similar- in a twin) affect the efficiency?&lt;/p&gt;&#xA;" OwnerUserId="1032" LastEditorUserId="258" LastEditDate="2015-09-07T00:03:48.587" LastActivityDate="2015-09-07T15:25:49.617" Title="Does the direction of counter-rotating props affect efficiency?" Tags="&lt;propeller&gt;&lt;efficiency&gt;&lt;model-aircraft&gt;&lt;p-factor&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20737" PostTypeId="2" ParentId="20733" CreationDate="2015-09-07T02:03:15.553" Score="9" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/11956/do-any-manufacturers-have-plans-to-use-turbojets-in-future-aircraft-what-is-the/11957?s=1%7C0.2475#11957&quot;&gt;Early jet engines&lt;/a&gt; had only one set of compressor disks which were sitting on the same shaft and spinning at the same speed. More modern designs use two or even three concentric spools, each spinning at its own speed. All spools have several compressor discs at the forward and one or a few turbine discs at the rear end, and allowing them to run at different speeds allows each compressor-turbine combination to run more efficiently. Note that all compressor components &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;increase pressure downstream&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gas turbines must be able to run efficiently not only at full thrust, but also at &lt;a href=&quot;https://aviation.stackexchange.com/questions/1858/at-what-point-during-a-long-flight-do-commercial-airliners-have-the-best-gas-mil/1860#1860&quot;&gt;intermediate thrust settings&lt;/a&gt;. Especially in cases where the airplane is not fully loaded, airlines prefer to reduce thrust somewhat, because this stresses the engine less. Enabling different speeds allows to adapt the engine better to the operating conditions. Adding a spool adds complexity and &lt;a href=&quot;https://aviation.stackexchange.com/questions/16709/why-should-jet-engine-throttles-be-moved-smoothly/16726?s=3%7C0.0796#16726&quot;&gt;introduces new failure modes&lt;/a&gt;, but the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13837/given-the-same-engine-why-install-a-gearbox-on-a-turboprop-but-not-on-a-turbofa/13839?s=1%7C0.2296#13839&quot;&gt;difference in speeds between the components&lt;/a&gt; makes obvious how much benefit they bring. In case of the &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/EASA-TCDS-E.002_(IM)_General_Electric_GE90_series_engines-02-16032004.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE-90&lt;/a&gt;, the low pressure spool runs at 2261.5 RPM when N1 is 100%, and the high pressure spool runs more than four times faster at 9332 RPM when N2 is 100%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Holdings&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce&lt;/a&gt;'s success in the engine market is largely due to its ability to tailor its &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Trent&quot; rel=&quot;nofollow noreferrer&quot;&gt;Trent engine&lt;/a&gt; to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9339/what-is-the-difference-between-boeing-777-31h-and-boeing-777-31her/9345#9345&quot;&gt;many variants of aircraft&lt;/a&gt; which are sold by Boeing and Airbus. This tailoring is done by adapting the low speed components while leaving the core identical between models. By having three components to tinker with while its competitors &lt;a href=&quot;https://en.wikipedia.org/wiki/GE_Aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;General Electric&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney&lt;/a&gt; have only two, Rolls-Royce has an advantage in the business of offering tailor-made engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason for having two independent rotating assemblies can be found on vertical take-off jets: By &lt;a href=&quot;https://aviation.stackexchange.com/questions/700/uniform-turbine-rotation-direction/7425?s=17%7C0.0484#7425&quot;&gt;spinning the low- and the high-pressure components in different directions&lt;/a&gt;, their gyro forces can be greatly reduced. While this is not relevant to regular airplanes, hovering a vertical take-off jet is much simpler when its engine does not add a pitch motion to every yawing motion and vice versa.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-03-25T22:59:06.193" LastActivityDate="2019-03-25T22:59:06.193" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="20738" PostTypeId="2" ParentId="20730" CreationDate="2015-09-07T02:13:54.443" Score="10" Body="&lt;p&gt;When I sail we use simple air horns to signal the local drawbridges. Something like &lt;a href=&quot;http://www.uline.com/Product/Detail/S-13530/Traffic-Safety/Air-Horns?pricode=WY840&amp;amp;gadtype=pla&amp;amp;id=S-13530&amp;amp;gclid=Cj0KEQjwyK-vBRCp4cymxermx-EBEiQATOQgh-CkjUK2ghv7DLGjpfpqTKTm3el8aLKbax5agShvhDoaAjWG8P8HAQ&amp;amp;gclsrc=aw.ds&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt; is usually kept on the boat. I see no reason not to keep one in your float plane if you anticipate need to hail a draw bridge or just for general marine hailing. If memory serves, it's one long blast (4-6 seconds) followed by a quick one. Similarly you could opt to carry a hand held &lt;a href=&quot;http://www.westmarine.com/buy/west-marine--vhf160-floating-6w-handheld-vhf-radio--14078562&quot; rel=&quot;nofollow noreferrer&quot;&gt;marine radio&lt;/a&gt; in your plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now all of that is assuming you knew you were going to encounter a bridge. If you did not plan for it then you have a few options. If memory serves some (if not all) of the bridges have land lines and if you have a cell phone you may be able to call them (provided you can find the number). If you are flying a float plane you may (should?) have a PFD on board. Many PFDs have whistles attached. This, in theory should suffice to hail the bridge. The bridge attendant may see you floating there and open the bridge as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can always try, um, yelling at the guy... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now what if the bridge is broken, there is a long train stuck on it and the attendant stepped out for a cigar break and has no intention of returning for a while? You are in the end of the day in a float plane and you have a unique ability that most ships don't have, you can go over the bridge... &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="8282" LastEditDate="2017-07-29T11:38:35.717" LastActivityDate="2017-07-29T11:38:35.717" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20739" PostTypeId="1" CreationDate="2015-09-07T06:42:40.017" Score="10" ViewCount="24781" Body="&lt;p&gt;Out of curiosity at what temperatures are the exhaust gasses are expelled from jet engines? A normal reciprocating engine from what I recall should be in the 700 - 1100 degrees Celsius range. Does this apply to turbofans/turboprops/turbojet engines also since the fuel properties should be similar? Or are the temperatures much lower as the engine is being used mostly at high altitudes?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-10-01T18:00:17.467" LastActivityDate="2015-10-01T18:00:17.467" Title="What is a normal EGT range of a jet engine?" Tags="&lt;jet-engine&gt;&lt;egt&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20740" PostTypeId="2" ParentId="20715" CreationDate="2015-09-07T08:11:59.057" Score="8" Body="&lt;p&gt;The answer doesn't state that half of the flights between western Europe and North America use the North Atlantic Oceanic Track System (OTS). It states that half of the flights over the North Atlantic use the OTS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the flights over the North Atlantic don't cross between western Europe and North America and they don't use the tracks. Examples are flights to/from Iceland or the Azores. Also flights crossing between Ireland and the North Western point of Spain are entering the North Atlantic Region.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also part of the flights that do cross between western Europe and North America and vice versa may use random routing for various reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On some days the winds are such that favourable tracks to North America are within the Reykjavik control area, which allows for random routings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some combinations of origin / destination are better served by avoiding the OTS area at all. For example flights between the Iberian peninsula and Florida are generally South of the OTS. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-07T08:27:43.553" LastActivityDate="2015-09-07T08:27:43.553" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20741" PostTypeId="2" ParentId="20739" CreationDate="2015-09-07T09:04:18.283" Score="11" Body="&lt;h2&gt;Turbofan without afterburner&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In non-afterburning engines the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;exit temperature inside the nozzle is around 600°C&lt;/a&gt; at full continuous thrust. If the ambient temperature is low, less heating is needed for the same thrust, and exit temperatures are lower. The maximum temperature for a given engine is, however, independent of altitude and given by the materials inside the engine. In flight the continuous maximum can be higher than on the ground, when the cooling by the external flow is less effective.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Temperature profile at a distance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.chemtrailplanet.com/PDF/JETEXHAUST.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This report&lt;/a&gt; gives results of ground measurements on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT8D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney JT8D&lt;/a&gt; of the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-9&quot; rel=&quot;nofollow noreferrer&quot;&gt;Douglas DC-9&lt;/a&gt; and shows how quickly the temperature drops behind the aircraft due to mixing and radiation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7X8iz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7X8iz.png&quot; alt=&quot;Jet temperature behind a DC-9 at take-off power&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Jet temperature behind a DC-9 at take-off power. Picture &lt;a href=&quot;http://www.chemtrailplanet.com/PDF/JETEXHAUST.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bY2EI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bY2EI.png&quot; alt=&quot;Jet temperature behind a DC-9 at idle power&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Jet temperature behind a DC-9 at idle power. Picture &lt;a href=&quot;http://www.chemtrailplanet.com/PDF/JETEXHAUST.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;With afterburner&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;With full afterburner the engine uses approximately five times as much fuel as when running dry, and it shows in the exhaust gas temperature. &lt;a href=&quot;http://www.nasa-usa.de/centers/dryden/pdf/88068main_H-1375.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This report&lt;/a&gt; details measurements of nozzle pressures and temperatures on one of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_F404&quot; rel=&quot;nofollow noreferrer&quot;&gt;General Electric F-404&lt;/a&gt; engines used in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_X-29&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-29 program&lt;/a&gt;. The plot below is taken from the report and shows exhaust-jet temperature summaries in the horizontal centerline for various power settings (PLA = power level angle; 120° is full afterburner and 87° is military thrust).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nhxDQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nhxDQ.png&quot; alt=&quot;Nozzle temperature survey of the GE F-404 afterburning engine&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Nozzle temperature survey of the GE F-404 afterburning engine. &lt;a href=&quot;http://www.nasa-usa.de/centers/dryden/pdf/88068main_H-1375.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The test conditions were 30.000 ft altitude and Mach 0.3, simulated in an altitude chamber. The temperatures were measured with a rake just a few inches aft of the engine nozzle. Note that the temperatures are given in &lt;a href=&quot;https://en.wikipedia.org/wiki/Rankine_scale&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rankine&lt;/a&gt;; the maximum of 3800°R is 1838°C. The wake of the engine's center body causes lower temperatures in the center of the jet at XSRL&amp;nbsp;=&amp;nbsp;0. The nozzle edge is at 12.7 inches from the center; due to symmetry only one half of the jet temperature profile is shown.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-08T17:37:21.010" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20743" PostTypeId="1" CreationDate="2015-09-07T13:50:11.277" Score="38" ViewCount="29259" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/news/press_releases/news_story.cfm?newsId=14838&quot; rel=&quot;noreferrer&quot;&gt;The FAA requires 1500 hours as a pilot&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The rule requires first officers — also known as co-pilots — to hold an Airline Transport Pilot (ATP) certificate, requiring 1,500 hours total time as a pilot. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I am just interested in how can you get 1500 hours? This number is super huge unless you fly a trans-continental airliner. But you cannot fly an airliner without 1500 hours. Even having a private airplane, 1500 hours I assume will cost a lot - probably more than €500,000 in Europe. What is so specific about the USA? I fly gliders and a tug plane. I fly every weekend without exception and even sometimes after work. But I won't reach even 100 hours during the season. So to reach 1500 hours will take 20+ years. What about if you fly aerobatics...? Well of course there are some people who have these numbers but they are in their fifties and have spent all their lives in aviation! They don't even think about starting afresh in a first officer's career. So I am just curious how do young people log 1500 hours in the USA?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="9276" LastEditDate="2017-04-27T12:08:18.340" LastActivityDate="2021-01-29T12:53:16.377" Title="How do young pilots in the USA accumulate 1500-hours to become a first officer?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20744" PostTypeId="2" ParentId="19458" CreationDate="2015-09-07T14:02:25.017" Score="1" Body="&lt;p&gt;I also found a link to &lt;a href=&quot;http://adg.stanford.edu/aa241/propulsion/engmodel.html&quot; rel=&quot;nofollow&quot;&gt;this (poorly working) Java applet&lt;/a&gt; for calculating the values. It is part of &lt;a href=&quot;http://adg.stanford.edu/aa241/AircraftDesign.html&quot; rel=&quot;nofollow&quot;&gt;Aircraft Design course on Stanford&lt;/a&gt; which will hopefully list the formulas used.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-09-07T14:02:25.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20745" PostTypeId="1" AcceptedAnswerId="20750" CreationDate="2015-09-07T14:32:05.327" Score="15" ViewCount="21721" Body="&lt;p&gt;As per subject, what is the lifespan of a jet engine? Do they have a fixed hours which they can be used and regardless of the state have to be exchanged or are they serviced and maintained until they are deemed not good for use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they do have a lifespan, I suppose also that different types of airliner engines and models will have different lifespans. &lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2019-07-27T21:06:19.293" Title="What is the lifespan of an airline engine?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20746" PostTypeId="2" ParentId="20743" CreationDate="2015-09-07T15:17:14.487" Score="31" Body="&lt;p&gt;1 word: Instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I learned to fly in the US, and all but one of the 10-15 instructors at the school were young guys who had a Commercial license and were just building hours while doing their exams and applying to airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This meant they were actually getting paid (not particularly well, I hasten to add!) to build hours, rather than spending money on an airplane, or rental.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They say you don't become a pilot for the money, you do it because you love it. Nothing could be closer to the truth IMO.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-09-07T15:17:14.487" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="20747" PostTypeId="2" ParentId="20743" CreationDate="2015-09-07T15:22:54.573" Score="18" Body="&lt;p&gt;I think the most common answer will be, instructing. You'll build hours much faster doing that, since it sounds like you're only getting about 100 hours / year now, which isn't much.  Of course, the difference between a good instructor job and a bad one can be huge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other routes, which are not necessarily incompatible with instructing, would be things like traffic watch flying and banner tow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point, most pilots probably start flying for somebody in a job that doesn't require ATP minimums -- night cargo, tour flying, etc. These jobs aren't entry level so they'll require some amount of experience, but not 1500 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One pilot I know started doing right seat work at SimuFlight, filling the seat &amp;amp; reading the checklist for pilots who came in for the course without their own copilot. Eventually got an offer to start flying right seat for one of the pilots that came through for refresher training.  That's hardly common, but one-off stuff like that is out there.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="4269" LastEditDate="2015-09-08T07:16:56.810" LastActivityDate="2015-09-08T07:16:56.810" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20748" PostTypeId="2" ParentId="20735" CreationDate="2015-09-07T15:25:49.617" Score="5" Body="&lt;p&gt;It might. Depending on how close to the wingtips your props are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you put the props right at the wingtips, then the conventional rotation to minimize precession and torque actually decreases efficiency by promoting tip vortex (the direction of the prop is the same as tip vortex thereby adding to tip vortex). This reduces lift for the same amount of airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, rotating it the other way round - away from each other - reduces tip vortex by twisting the slipstream the opposite direction as the tip vortex. This increases lift (technically, it reduces the reduction of lift due to tip vortex) for the same amount of airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One plane that exploited this was the Vought XF5U - the Flying Pancake. The direction of prop rotation is fairly obvious in this picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FlQEG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FlQEG.jpg&quot; alt=&quot;Vought XF5U&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The interesting result of this was that even though the XF5U had very short wingspan it could do short take-offs.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-09-07T15:25:49.617" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20749" PostTypeId="2" ParentId="9315" CreationDate="2015-09-07T16:38:30.090" Score="0" Body="&lt;p&gt;Flaps and spoilers(airbrakes) have a similar affect by creating more drag. However, they have the opposite affect when it comes to creating lift. A great way to think of this is the car analogy. There are two ways to slow down a car: the hydraulic brakes and the engine brakes. Hydraulic brakes, analogous to spoilers/airbrakes, decreases revs as it slows down the vehicle. On a standard transmission, applying the brakes without hitting the clutch will eventually cause revs to go to low and stall the car. Similarly on an aircraft, using spoilers will increase the angle of attack(decrease lift) and of course increase stall speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, flaps work like engine brakes. If I'm cruising at 50 mph(80 km/h) and my revs are at 1500 rpm in 6th, and I put my car in 5th while maintaining the same speed, I will have to increase the power I put and my revs will jump to about 2000. SAME CONCEPT IN AN AIRCRAFT! If I'm cruising at 180 knots IAS and my angle of attack is 10 degrees, and I apply flaps from up to 10 degrees, the engine will have to use more power to maintain 180 knots IAS, but my angle of attack will decrease, and I'll get more lift. Just like a car has speed limits for its gears, aircrafts have maximum speeds to use every level of flaps. Using engine brakes can help you slow down just like flaps can help you fly at a lower speed and eventually land at an optimal speed. &lt;/p&gt;&#xA;" OwnerUserId="11126" LastActivityDate="2015-09-07T16:38:30.090" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20750" PostTypeId="2" ParentId="20745" CreationDate="2015-09-07T16:46:18.867" Score="13" Body="&lt;p&gt;In general, the engine life is measured in terms of two things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight hours&lt;/li&gt;&#xA;&lt;li&gt;Flight cycles&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A takeoff and a landing counts as a flight cycle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important concept in engine life is the Time Between Overhaul(TBO), which is basically the manufacturer recommended time period after which the engine is stripped down,checked thoroughly and required parts replaced. After overhaul, the engine is usually cleared till the next TBO. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An overhauled engine is theoretically as good as a new one and comes with the same life (TBO) and warranty, if applicable. Airline engines (for example the Rolls Royce Trent series) usually have TBOs of over 15000 hours. The record for maximum time for an engine on wing (i.e. use in aircraft before removal for overhaul) is well over 40,000 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The life of an engine is given by the manufacturer and are different for different engines. However, the engine life depends on a number of parameters and is usually different for various engine components. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The rotating components have life limits which are less than the engine and are replaced periodically, mostly during the TBO.&lt;/li&gt;&#xA;&lt;li&gt;For example, the turbine blades are replaced after a set number of turbine cycles and/or after a set number of hours, which are lesser than the others.&lt;/li&gt;&#xA;&lt;li&gt;In addition, most rotating components (compressors, turbines) are periodically subjected to checks, and are replaced if found damaged.&lt;/li&gt;&#xA;&lt;li&gt;In case of abnormal operations, some parts are required to be replaced. For example, if one engine is required to give excessive thrust (for example in case of One Engine Inoperative), the engine is subjected to thorough checks similar to TBO.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Airline engines are usually serviced (Overhauled at TBOs) and maintained till they are deemed not good to use or not economical to (service/repair and) operate anymore. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the engine manufacturers employ condition based health monitoring programs, which helps them to plan when to service and repair the engine. As a result, the engine life varies based on its condition.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="679" LastEditDate="2015-09-08T02:21:32.430" LastActivityDate="2015-09-08T02:21:32.430" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20751" PostTypeId="1" CreationDate="2015-09-07T17:04:32.547" Score="-3" ViewCount="282" Body="&lt;p&gt;From Aviation Herald, A320s have reported 6 issues in just last three days.  What are some possible reasons for such bugs ,like AI 405 had a hydraulic leak, and B6-907 had a hydraulic failure. Are the airline engineering teams to be blamed for such incidents?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2015-09-07T17:39:23.317" Title="Why are A320s around the world reporting so many problems these days?" Tags="&lt;safety&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-09-07T19:15:42.630" ContentLicense="CC BY-SA 3.0" />
  <row Id="20752" PostTypeId="2" ParentId="20739" CreationDate="2015-09-07T17:13:33.757" Score="7" Body="&lt;p&gt;The exhaust gas temperature of a jet engine depends on a number of parameters like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The operating conditions&lt;/li&gt;&#xA;&lt;li&gt;Whether afterburner is used or not&lt;/li&gt;&#xA;&lt;li&gt;The condition of the engine&lt;/li&gt;&#xA;&lt;li&gt;Type of the engine (whether low or high bypass turbofan etc)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Without after burner, the exhaust gas temperature is around 600-650 $^{\circ}$ C, which goes upto 1500 $^{\circ}$C with after burner. The figure below shows the data for General Electric J79 low bypass turbofan engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ToMeu.jpg.&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ToMeu.jpg.&quot; alt=&quot;GE J79&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.aircraftenginedesign.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of high bypass turbofan engines, the exhaust gas temperature is slightly lower, usually around 500-600 $^{\circ}$ C. For example, the figure shows the temperature variation in PW 4000 engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ghnkw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ghnkw.jpg&quot; alt=&quot;PW 4000&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: web.mit.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature of the engine is determined by the materials used, especially the turbine temperatures (and method of cooling), and not much on outside conditions. As such, the turbine gas temperature is the highest temperature in jet engines and the limiting factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Exhaust gas temperature is a parameter to measure engine health. A high EGT for a given thrust (by a engine) is a sign that the engine required more fuel for the same thrust, due to wear out of rotating components, etc, and the engine may require inspection.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-07T17:13:33.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20753" PostTypeId="2" ParentId="20751" CreationDate="2015-09-07T17:39:23.317" Score="9" Body="&lt;p&gt;A statement like &quot;model X has reported Y failures in Z days&quot; is not relevant in aviation. In aviation what is relevant is the mean time between failures [meaning &lt;em&gt;the same type of failure&lt;/em&gt;] (in short MTBF): it is the mean time, &lt;strong&gt;fleet-wise&lt;/strong&gt;, between two failures (example, two engine failure concerning the same component). The relevant part, is the &quot;fleet-wise&quot;: if there would be only 1 A320 in operation, 2 issues a day would bee too many indeed, with hundreds (thousands?) of A320s in service, flying hundreds of hours each day all over the world, I would say that 2 issues a day is a quite decent record.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-09-07T17:39:23.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20754" PostTypeId="2" ParentId="9315" CreationDate="2015-09-07T19:51:34.997" Score="2" Body="&lt;p&gt;It's bad to compare flaps and speed brakes and use flaps as brakes. They are meant for different things. To slow down and to make stall speed slower. Of course it's possible to use flaps as speed brakes but it's a bad practice. Boeing 737 flight manual warn's pilots not to use flaps to slow down. High performance aircraft usually has both. Another important think is that speed brakes doesn't have speed limit. Flaps have speed schedule and are meant only for slow speed. For example you want to descent fast you maintain maximum speed and extend brakes. &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-09-07T19:51:34.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20755" PostTypeId="2" ParentId="20688" CreationDate="2015-09-07T21:04:58.107" Score="2" Body="&lt;p&gt;When my planned route is GPS-direct (no intermediate waypoints), my route of flight looks something like &quot;KXYZ Direct KABC&quot;. In that case, I create two quasi-waypoints on my NavLog: TOC (top-of-climb) and DP (descent point). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I calculate time, distance, and fuel burn for the climb based on appropriate table(s) in the POH (adjusted for winds as necessary), and enter those for the TOC waypoint (marking the calculated point on my chart). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I calculate my descent profile based on my planned descent airspeed, rate-of-descent, cruise altitude, and predicted winds; I want to be stabilized at pattern altitude (or appropriate overflight altitude) before I reach the airport. I enter the DP based on those calculations (and mark the calculated point on my chart). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then it's a simple matter of subtracting the Climb and Descent legs from the total distance to derive the Cruise leg distance with appropriate time and fuel-burn based on the POH (adjusted for predicted winds, of course). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The resulting NavLog has four waypoints: Departure Airport, TOC, DP, and Destination Airport.&lt;/p&gt;&#xA;" OwnerUserId="10043" LastActivityDate="2015-09-07T21:04:58.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20756" PostTypeId="2" ParentId="17621" CreationDate="2015-09-07T21:44:46.143" Score="1" Body="&lt;p&gt;In general aviation applications, navigation database and software updates are downloaded over the internet from the avionics manufacturer, and stored on an SD card, which is later inserted into an SD card slot in the bezel of the avionics in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Downloads are restricted to registered subscribers.&lt;/p&gt;&#xA;" OwnerUserId="10043" LastActivityDate="2015-09-07T21:44:46.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20757" PostTypeId="2" ParentId="17621" CreationDate="2015-09-07T22:41:58.613" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://www.rockwellcollins.com/Services_and_Support/Database_and_Software_Updates/Navigation_Databases.aspx&quot; rel=&quot;nofollow&quot;&gt;Rockwell Collins FMS&lt;/a&gt; units found in many large airliners are updated via USB stick. you can find a nice video &lt;a href=&quot;https://www.youtube.com/watch?v=g4TA3Or6bDU&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; on how its done. Most GA planes use SD cards (or other similar card formats) these days. Some people chose to use apps like ForeFlight on their iPad which is updated via the internet.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the &quot;chain of trust&quot; Rockwell Collins requires a &lt;a href=&quot;http://www.rockwellcollins.com/Services_and_Support/Database_and_Software_Updates/~/link.aspx?_id=96E76623B4854FC3AD1A8741902542AF&amp;amp;_z=z&quot; rel=&quot;nofollow&quot;&gt;subscription&lt;/a&gt; to their FMS database downloads however they are downloaded straight from the internet. There is a list of &lt;a href=&quot;http://www.rockwellcollins.com/Services_and_Support/Database_and_Software_Updates/Navigation_Databases/Database_Alerts_and_Certifications.aspx&quot; rel=&quot;nofollow&quot;&gt;addendum and alterations&lt;/a&gt; which some airlines apparently have. In reality the medium is not &quot;secure&quot; as you mention but tampering with it would be in violation of some FAR (I'll try and find the one) since you would potentially create a hazardous situation. I'm sure airlines and A&amp;amp;P shops are diligent about these updates the same way they are about any maintenance. I'm not sure if there is any software level encryption on the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For apps like ForeFlight and some of the more GA directed markets (that are not using full FMS systems) the FAA makes all of their charts available in &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/&quot; rel=&quot;nofollow&quot;&gt;digital form for free&lt;/a&gt;. I would assume this is where places like ForeFlight get their data and then, as a user, you download it from the ForeFlight servers. Again you pay a subscription to ForeFlight to guarantee that these things are on line and up to date. Again this is all not very secure (in a manner of speaking) and you are relying on ForeFlight to not tamper with the maps. When talking about updating the maps in a GA plane chances are it's &lt;em&gt;your&lt;/em&gt; plane and you are responsible to ensure its &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/continued_operation/ad/gen_resp/&quot; rel=&quot;nofollow&quot;&gt;safe operation&lt;/a&gt;. Garmin seems to make their downloads &lt;a href=&quot;http://www8.garmin.com/support/collection.jsp?product=010-G1000-00&quot; rel=&quot;nofollow&quot;&gt;available right on their site&lt;/a&gt;.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-04-27T15:43:09.480" LastActivityDate="2016-04-27T15:43:09.480" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20758" PostTypeId="1" CreationDate="2015-09-08T03:20:47.500" Score="5" ViewCount="2331" Body="&lt;p&gt;Why are &lt;a href=&quot;https://en.wikipedia.org/wiki/Combi_aircraft&quot;&gt;combi&lt;/a&gt; airliners no longer being built?  Is the reason structural, economic or regulatory?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2020-06-07T19:22:22.083" Title="Why are combi airliners no longer being built?" Tags="&lt;aircraft-design&gt;&lt;airline-operations&gt;&lt;regulations&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20759" PostTypeId="2" ParentId="20758" CreationDate="2015-09-08T04:03:48.437" Score="2" Body="&lt;p&gt;I think the term is being slightly misused :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A combi aircraft is not a type of aircraft to be &lt;strong&gt;built&lt;/strong&gt;, but rather an aircraft that is simply &lt;strong&gt;configured&lt;/strong&gt; to transport both passengers and freight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.alaskaair.com/content/travel-info/our-aircraft/737-400-combi.aspx&quot; rel=&quot;nofollow&quot;&gt;Alaska&lt;/a&gt; is an example of an airline that uses aircraft configured in this fashion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason they aren't more widespread is that they inhibit &lt;a href=&quot;https://en.wikipedia.org/wiki/Economies_of_scale&quot; rel=&quot;nofollow&quot;&gt;economies of scale&lt;/a&gt;. They are more difficult to use effectively - you need a special purpose for them.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-09-08T04:03:48.437" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20760" PostTypeId="2" ParentId="20758" CreationDate="2015-09-08T04:34:51.907" Score="5" Body="&lt;p&gt;While combi configurations are rare, they do have a place -- for instance, when operating narrowbodies into remote locations which have a demand for cargo that exceeds what can be put in the belly, but also need pax transport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most recent combi configuration I can find a source for is the &lt;a href=&quot;http://www.atl.aero/ironmaiden&quot; rel=&quot;nofollow&quot;&gt;2008 work done by Aviation Traders to configure Iron Maiden's touring plane&lt;/a&gt;.  In this case, they used the existing seat rails to mount pallet fittings in order to avoid structural changes to the floor, and also are taking special steps (such as firebagging of cargo) to mitigate against a main deck cargo compartment fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to why they aren't made otherwise?  It clearly isn't operating economics, at least for Alaska Airlines, Canadian North, First Air, and other current combi operators -- otherwise they'd have retired their combis by now.  The main issue, I strongly suspect, is actually the unsolved problem of fire suppression in large, main deck class B cargo compartments, such as those found on combi aircraft.  Aviation Traders' work on Class F is intended to solve this problem, made famous by the crash of &lt;a href=&quot;https://en.wikipedia.org/wiki/South_African_Airways_Flight_295&quot; rel=&quot;nofollow&quot;&gt;SAA 295&lt;/a&gt; after its main deck class B bay experienced a fire of unknown origin that proved catastrophic.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-09-08T16:13:25.953" LastActivityDate="2015-09-08T16:13:25.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20761" PostTypeId="1" AcceptedAnswerId="20762" CreationDate="2015-09-08T04:40:47.073" Score="5" ViewCount="899" Body="&lt;p&gt;Apparently, the Aviation Traders folks worked with EASA to define a special type of cargo compartment, known as a class F, during their work on &lt;a href=&quot;http://www.atl.aero/ironmaiden&quot;&gt;Iron Maiden's touring airplane&lt;/a&gt;.  Just what is a Class F cargo compartment, and how does it differ in safety properties from the large class B compartments used on earlier combi configured aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-09-08T07:58:12.077" Title="What's a Class F cargo compartment?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;easa-regulations&gt;&lt;aircraft-certification&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20762" PostTypeId="2" ParentId="20761" CreationDate="2015-09-08T07:58:12.077" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://easa.europa.eu/system/files/dfu/NPA%202008-10.pdf&quot; rel=&quot;nofollow&quot;&gt;Here in this amendment to the EASA CS-25&lt;/a&gt; it says on page 4:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... for a new Class B cargo&#xA;  compartment definition as well as design criteria for a new Class F cargo compartment&#xA;  type. This latter class of compartment was introduced because whilst it was concluded&#xA;  that manual fire fighting was not feasible for larger compartments, alternatives other&#xA;  than just the existing Class C were identified. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And a bit further on page 5 (emphasis mine) :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... Further, a new Class F cargo&#xA;  compartment definition is added, &lt;strong&gt;which is not limited in size and which provides the&#xA;  means to control or extinguish a fire without requiring a crewmember to enter the&#xA;  compartment.&lt;/strong&gt; This proposed Class F compartment standard accommodates the carriage&#xA;  of large amounts of baggage and cargo loads on Combi aeroplanes as well as in&#xA;  compartments of smaller sizes exceeding the new Class B definition. New aeroplanes&#xA;  designs can take advantage from the variable solutions under the Class F definitions to&#xA;  ensure an acceptable level of fire protection. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And more concrete:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The AMC further provides guidance for usage of other fire&#xA;  protection means in the new Class F compartment such as Fire Containment Covers&#xA;  (FCC) or Containers rather than having a liner installed to contain a fire and to protect&#xA;  the critical systems and structure of the aeroplane. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess it's meant to allow storage of cargo in non-cargo areas (which do not have the adequate fire protection measures such as liners) if other non-traditional measures are installed (such as the Fire Containment Covers)&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-09-08T07:58:12.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20763" PostTypeId="2" ParentId="20743" CreationDate="2015-09-08T09:00:05.310" Score="12" Body="&lt;p&gt;Instructing is the most common route, however you can also fly as a commercial pilot in part 135 operations, which would be anything 30 seats or under charter, or 9 seats or less as a scheduled flight, and &amp;lt;= 7500 lbs payload. &lt;a href=&quot;http://www.researchintegrations.com/components/com_wordpress/wp/wp-content/uploads/2013/09/unravelling-op-req-applicabilty-table-1.jpg&quot;&gt;This link&lt;/a&gt; helps explain the differences. This would be small commuter airplanes, cargo, and air taxi operations. Also, experience does not have to come from US regulated air operations, you could go elsewhere in the world where the 1500 hour rule does not apply and get experience as a first officer and it should still count.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-09-08T15:49:54.733" LastActivityDate="2015-09-08T15:49:54.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20764" PostTypeId="1" CreationDate="2015-09-08T13:24:13.933" Score="2" ViewCount="673" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Bristol_Brabazon&quot; rel=&quot;nofollow&quot;&gt;According to Wikipedia&lt;/a&gt;, 6 million pounds were spent developing the Bristol Brabazon, and the only prototype was scrapped for 10,000 pounds, that is a 0.17% loss recoup. There was a lot more value in keeping that plane intact than scrapping it, maybe for future projects, or special assignments, or further testing, like an An-225. It held more value as a museum piece, or a &quot;sculpture&quot; in Bristol, than the value from the scrap metal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was there a reason for being scrapped, other than the 10k in scrapped metal? &lt;/p&gt;&#xA;" OwnerUserId="9939" LastEditorUserId="1696" LastEditDate="2015-09-08T20:56:33.113" LastActivityDate="2015-09-09T07:27:10.147" Title="Why was the Bristol Brabazon scrapped?" Tags="&lt;commercial-aviation&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20765" PostTypeId="2" ParentId="20764" CreationDate="2015-09-08T13:55:10.597" Score="1" Body="&lt;p&gt;You should also consider maintenance costs. Keeping the airplane will surely cause some kind of cost and the maintaining party has to cover them somehow. Even if you have museum admissions or the like you still must have it running well enough to cover the quite high costs of keeping your airplane together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That they did not keep it for further research indicates IMHO that the plane was simply not seen as a good fundament for further research.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am very sure that the people in charge back then did consider carefully what they do with it. For some reason they would rather write off almost 6 mio and get the money for the scrap metal. Even though mistakes happen a lot, I think that they knew what they did :)&lt;/p&gt;&#xA;" OwnerUserId="3916" LastActivityDate="2015-09-08T13:55:10.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20766" PostTypeId="1" CreationDate="2015-09-08T14:25:34.830" Score="22" ViewCount="5883" Body="&lt;p&gt;How do the Boeing aircraft taxi to &lt;a href=&quot;https://www.airnav.com/airport/KPAE&quot; rel=&quot;noreferrer&quot;&gt;Paine Field (KPAE)&lt;/a&gt; from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Everett_Factory&quot; rel=&quot;noreferrer&quot;&gt;Everett Factory&lt;/a&gt;? It looks like a 'road' connecting the airport and the factory. Do they use this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Everett_Factory#/media/File:Aerial_Boeing_Everett_Factory_October_2011.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T1pVl.jpg&quot; alt=&quot;Boeing Everett Factory from Wikipedia&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11133" LastEditorUserId="39" LastEditDate="2015-09-08T21:25:02.820" LastActivityDate="2017-12-31T08:47:32.887" Title="Where is the taxiway between the Boeing factory and Paine Field airport?" Tags="&lt;airport&gt;&lt;taxiing&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20767" PostTypeId="2" ParentId="20758" CreationDate="2015-09-08T14:45:33.333" Score="5" Body="&lt;p&gt;Combi aircrafts are basically modified airliners that carry passengers and/or cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though there are multiple reasons for not combi aircrafts not in use nowadays, the main reason is economic. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of mixed passenger/cargo operations, the cargo is usually one directional. The aircraft will be half empty in the return flight.&lt;/li&gt;&#xA;&lt;li&gt;The conversion of passenger aircrafts involve some significant structural changes like cutting open a cargo loading door.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/304xw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/304xw.jpg&quot; alt=&quot;787 Cargo door&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.airtransport.cc&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air cargo is highly seasonal, while the passenger traffic is not (Except for some spikes during festive occasions). It makes little economic sense to operate combi aircraft while passenger and cargo aircrafts can be operated separately more economically. &lt;/li&gt;&#xA;&lt;li&gt;The conversion of he aircraft to carry cargo is not one of simply removing seats. it involves modification/installation of cargo handling systems, fire extinguishing systems etc. For example, air cargo pallets are standardized and cannot be transferred through cabin doors. The figure shows the work involved in the conversion of a Boeing 757&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/syKEX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/syKEX.jpg&quot; alt=&quot;757 modification&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: staero.aero &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The airline passenger traffic has grown enormously through th years, while the air cargo has not seen such robust growth. So it makes sense to concentrate on only a single sector.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sqGjZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sqGjZ.png&quot; alt=&quot;Air passenger and cargo volumes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: centreforaviation.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only places combi aircraft are used are those in which operating such aircraft is necessary. Simply put, combi aircrafts belong to another age of air transportation, while in the present (and near future), it makes more economic sense to operate specialized passenger and freight aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-08T14:45:33.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20768" PostTypeId="1" AcceptedAnswerId="20769" CreationDate="2015-09-08T14:58:42.680" Score="18" ViewCount="985" Body="&lt;p&gt;I've seen ATCs use little slides with flight numbers for tracking arrivals and departures - is there a term for them and are they still used today with modern ATC terminals?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/acqUj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/acqUj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11134" LastActivityDate="2015-09-08T15:10:31.063" Title="What are the slides that ATCs use for tracking departures and arrivals?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20769" PostTypeId="2" ParentId="20768" CreationDate="2015-09-08T15:02:54.837" Score="17" Body="&lt;p&gt;Yes they are called &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_progress_strip&quot;&gt;flight progress strips&lt;/a&gt; or simply strips. They are still in use, though they tend to be replaced more and more by the electronic strip or e-strip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also used by en-route controllers (not only terminal as you mentioned). From my experience from Athens ACC, PALLAS supports e-strips, but there is also a printer that prints them in some intervals (I don't remember what triggers the print). Note that some time ago, during the procedural control era, those were manually completed by the ATCOs. I guess they are still manually completed in TMAs and ACCs that use procedural control as primary method and lack RADAR service.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2015-09-08T15:10:31.063" LastActivityDate="2015-09-08T15:10:31.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20770" PostTypeId="2" ParentId="20766" CreationDate="2015-09-08T16:39:11.287" Score="36" Body="&lt;p&gt;That &quot;road&quot; is in fact a taxilane, and marked as such on the Paine Field side (note the yellow lead lines marked at the bottom of the image below, you would find on a taxiway). It connects the Boeing plant to Paine Field's &quot;Boeing Ramp&quot; where final prep can be completed before the aircraft are flown off to wherever they're going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XWZ1l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XWZ1l.jpg&quot; alt=&quot;Boeing bridge lead-lines&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The terminology is important here: The bridge acts as a &lt;em&gt;taxilane&lt;/em&gt; (a non-movement area not under the control of ATC which connects various aircraft parking areas to the &lt;em&gt;taxiways&lt;/em&gt;). Boeing coordinates their own movements between the main plant (north) and Paine Field's Boeing Ramp (south). (The bridge is also not depicted &lt;a href=&quot;https://i.stack.imgur.com/vdHBA.png&quot; rel=&quot;noreferrer&quot;&gt;on the airport diagram&lt;/a&gt; and may not even have &quot;taxilane&quot; status - as far as ATC is concerned. It's just sort of &quot;there&quot;.) &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-08T16:39:11.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20771" PostTypeId="2" ParentId="20766" CreationDate="2015-09-08T17:45:40.427" Score="24" Body="&lt;p&gt;The aircraft are moved from the factory to the airfield and paint shops on the airfield side over the bridge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The photo shows a 787 Dreamliner being moved across the bridge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/k8RuX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k8RuX.jpg&quot; alt=&quot;Boeing 787&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airlinereporter.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2032" LastEditDate="2015-09-08T19:01:20.357" LastActivityDate="2015-09-08T19:01:20.357" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20772" PostTypeId="1" AcceptedAnswerId="20782" CreationDate="2015-09-08T17:52:50.823" Score="3" ViewCount="2967" Body="&lt;p&gt;(GA Pilot)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a C-172 (G1000 Avionics), what would be the AutoPilot minimums OR at what altitude would one need to disengage the auto-pilot and take controls for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Precision Approaches&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Non-Precision Approaches&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Visual Approaches ..?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="1968" LastEditDate="2015-09-08T21:49:01.917" LastActivityDate="2015-09-08T21:49:01.917" Title="What are the Autopilot Minimums for a C-172 G1000?" Tags="&lt;general-aviation&gt;&lt;autopilot&gt;&lt;cessna-172&gt;&lt;g1000&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20773" PostTypeId="1" AcceptedAnswerId="20776" CreationDate="2015-09-08T18:08:39.437" Score="5" ViewCount="316" Body="&lt;p&gt;If you are in a modern GA aircraft, you may have a flight director and/or autopilot that can be coupled to your ILS receiver.  (Certainly, this is true of GA glass...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some ILS approaches provide a clause (marked by the * on the minimums and in the notes box on the plate shown below) which allows the RVR minimums to be reduced from 2400 to 1800 if you are using a flight director, HUD, or coupled autopilot to fly the approach to the decision altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E4wNb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E4wNb.png&quot; alt=&quot;KLNK ILS or LOC RWY 18&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Does this clause apply to light GA aircraft with the appropriate hardware (say a C172 with a G1000 in it), or is it limited to use by transport category/multi-crew operations?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="64" LastEditDate="2015-09-08T19:38:49.793" LastActivityDate="2015-09-08T19:38:49.793" Title="Can light GA aircraft with FDs or couplers use the RVR reduction clause on an ILS?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20776" PostTypeId="2" ParentId="20773" CreationDate="2015-09-08T19:31:19.090" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8400_13C.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Order 8400.13C&lt;/a&gt; outlines these procedures. Section 7 c outlines the requirements for this procedure. Most of these affect the airport facilities or procedures themselves, and section 5 b outlines the IAP requirements for aircraft:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft equipped with an operable FD, or AP with an approach coupler, or HUD which is certified for operation to a minimum of 200 feet HAT are eligible for this operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is also a note under 9 b:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Single pilot operators are prohibited from using the FD to reduced CAT I landing minimums without accompanying use of an AP with an approach coupler or HUD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it would appear that having a FD is not entirely sufficient; a pilot with a FD can use the reduced minimums if they also have one of the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;AP with approach coupler&lt;/li&gt;&#xA;&lt;li&gt;HUD&lt;/li&gt;&#xA;&lt;li&gt;Copilot&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-09-08T19:31:19.090" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20778" PostTypeId="1" AcceptedAnswerId="20780" CreationDate="2015-09-08T19:57:29.733" Score="6" ViewCount="672" Body="&lt;p&gt;Cuba and the US have long had &quot;frosty&quot; relations.&#xA;With some limited easing of restrictions, there are now direct flights between Miami, FL (controlled by ZMA) and Havana, Cuba.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does Cuba have an ARTCC?  Do they coordinate with ZMA for passing off flights?&lt;br&gt;Has this been an ongoing system even before the recent easing of sanctions, or is it relatively new?&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-09-19T15:38:29.030" Title="How does traffic handoff between ZMA and Cuba work?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20779" PostTypeId="2" ParentId="20764" CreationDate="2015-09-08T20:23:08.983" Score="8" Body="&lt;p&gt;You're right, as an exhibition piece it would had been quite an attraction. But it was not up to the Bristol company to decide her fate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During and after the war, most British aviation development was managed by the government. The Brabazon was the result of a committee which set the goal to develop a transatlantic airliner with 1943 technology, not by a company and its technological visionaries. If you had asked people like &lt;a href=&quot;https://en.wikipedia.org/wiki/Willy_Messerschmitt&quot; rel=&quot;noreferrer&quot;&gt;Willy Messerschmitt&lt;/a&gt; in 1943 how the future airliner would look like, he would had basically described a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;noreferrer&quot;&gt;Boeing 707&lt;/a&gt;: Swept wings, turbojet engines, pressurized cabin for about 100 passengers. But Government bureaucrats put the goal for the Brabazon quite differently, and the result was technically obsolete by the time it took to the air. Even before the Brabazon flew first on September 4, 1949, the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;noreferrer&quot;&gt;de Havilland Comet&lt;/a&gt; had already flown on July 27, 1949 and was on its way to revolutionize air travel. Its development had started later and was directed by engineers, not bureaucrats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When that became obvious, the bureaucracy felt too embarrassed to keep the Brabazon around. The situation was similar to &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft&quot; rel=&quot;noreferrer&quot;&gt;Beechcraft&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Starship&quot; rel=&quot;noreferrer&quot;&gt;Starship&lt;/a&gt;: Burt Rutan's 85% scale prototype was cut into pieces out of spite when it became eventually clear even for Beechcraft's board just what a turkey it was. The same fate befell the Brabazon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But its legacy for Bristol is still very positive - without the Brabazon, it would certainly not employ as many people in aerospace as it does up to this day. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-09T07:27:10.147" LastActivityDate="2015-09-09T07:27:10.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20780" PostTypeId="2" ParentId="20778" CreationDate="2015-09-08T20:39:54.093" Score="3" Body="&lt;p&gt;After some searching, I found a &lt;a href=&quot;https://www.wikileaks.org/plusd/cables/09HAVANA698_a.html&quot; rel=&quot;nofollow&quot;&gt;paper from Wikileaks&lt;/a&gt; from November 19th, 2009, that reads in part:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;(SBU) SUMMARY:  Miami and Havana air traffic controllers &#xA;  signed a letter of agreement (LOA) on November 12 updating &#xA;  procedures for the coordination of flights between Cuban and &#xA;  U.S. controlled airspace.  Both sides stressed the excellent &#xA;  working relationship between the Miami Air Route Traffic &#xA;  Control Center (ARTCC) and the Havana Area Control Center &#xA;  (ACC).  The U.S. delegation agreed to review information to &#xA;  be provided by the Cuban delegation regarding flights &#xA;  operating under the rules of &quot;due regard&quot; that could pose a &#xA;  safety risk.  Both sides also agreed to discuss switching &#xA;  from verbal to electronic flight data sharing, on the margins &#xA;  of a regional aviation meeting in Miami in May 2010. END &#xA;  SUMMARY &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apparently handoff procedures have been a regular occurrence for a long time, and are cooperated on extensively.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-09-08T20:39:54.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20781" PostTypeId="1" CreationDate="2015-09-08T21:23:30.447" Score="3" ViewCount="1738" Body="&lt;p&gt;I don't mean how much is the list price. I am asking how much does it cost for Boeing to buy the engine, wing, etc. and put it together and ship it. What is the total cost of ordering everything and putting it together?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1467" LastEditDate="2015-09-08T21:43:20.670" LastActivityDate="2015-09-08T21:43:20.670" Title="How much does it cost to build a Boeing 737 NG?" Tags="&lt;airliner&gt;&lt;boeing-737&gt;" AnswerCount="0" CommentCount="8" ClosedDate="2015-09-09T12:39:38.567" ContentLicense="CC BY-SA 3.0" />
  <row Id="20782" PostTypeId="2" ParentId="20772" CreationDate="2015-09-08T21:26:29.553" Score="6" Body="&lt;p&gt;Typically, the aircraft flight manual will identify this. In your particular case (Cessna 172 G1000), it is &lt;strong&gt;200 feet AGL&lt;/strong&gt; for all approach types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-172 can be fitted with either a Garmin GFC 700, or a Bendix/King KAP 140.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the GFC 700, it is listed in the aircraft operating limitations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/svk7B.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/svk7B.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the KAP 140, it is listed in the autopilot supplement:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WuqtM.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WuqtM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-09-08T21:40:12.463" LastActivityDate="2015-09-08T21:40:12.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20783" PostTypeId="2" ParentId="14405" CreationDate="2015-09-08T21:31:17.353" Score="6" Body="&lt;p&gt;So according to EASA, it is the &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/agency-measures-docs-opinions-2013-11-AMC-&amp;amp;-GM-to-Part-ATCO,-Part-ATCO.AR-&amp;amp;-Part-ATCO.OR.pdf&quot; rel=&quot;nofollow&quot;&gt;AMCs/GM for Regulation 2015/340, Part ATCO.OR (Annex III to Decision 2015/10/R)&lt;/a&gt; and specifically in &lt;code&gt;AMC1.ATCO.OR.C015(b)(b)&lt;/code&gt; where is specifies 11 criteria regarding STD standards, among them being accuracy of aircraft performance, voice recognition realism, equipment, data displays, etc:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;STD criteria&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If  a  synthetic  training  device  (STD)  is  used  for  training, it should&#xA;  be approved by the competent authority as part of the course approval process &#xA;  for  any  training  plan.  Training  organisations  should  demonstrate  how  the STD  will  provide  adequate  support  for the  intended training,  in  particular, how  the  STD  will  meet  the  stated  objectives  of  the  practical  training exercises and enable the performance objectives to be assessed to the level determined in the training programme.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This  demonstration  and  the  related  documentation  should  include  the &#xA;  following relevant criteria:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) the  general  environment,  which  should  provide  an  environment  in &#xA;  which  STD  exercises  may  be  run  without  undue  interference  from unrelated activities;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) the STD layout;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) the equipment provided;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) the  display  presentation,  functionality,  and  updating  of operational information;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) data displays, including strip displays, where appropriate;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) coordination facilities;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) aircraft   performance   characteristics,   including   the   availability   of manoeuvres,   e.g.   holding   or instrumental landing system   (ILS) operation, required for a particular simulation;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(8) the availability of real-time changes during an exercise;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(9) the  processes  by  which  the  training  organisation can be assured that staff associated with the training conducted with the use of an STD are &#xA;  competent;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(10) the degree of realism of any voice recognition system associated with &#xA;  the STD;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(11) where  a  simulator  is  an  integral  part  of  an  operational  ATC&#xA;  system, the  processes  by  which  the  training  organisation  is  assured  that interference  between  the  simulated  and  operational  environments  is prevented.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The  extent  to  which  the  STD  achieves  the above criteria  will  be  used  to determine  the  adequacy  of  the  STD  for  the  proposed  use.  As  a  general principle,  the  greater  the  degree  of  replication  of  the  operational  position being  represented  the  greater  the  use  will  be  possible  for  any  particular training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="878" LastEditorUserId="6886" LastEditDate="2015-09-22T03:32:44.457" LastActivityDate="2015-09-22T03:32:44.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20785" PostTypeId="1" AcceptedAnswerId="20787" CreationDate="2015-09-08T21:45:56.627" Score="1" ViewCount="1437" Body="&lt;p&gt;For the N1 fan and N2 compressor to move, the turbine needs to spin in an airliners engine. How does energy from the ignited gas spin this turbine? Do the blades on the turbine generate lift just like a wing and spin to spin the N1 fan and N2 compressor?&lt;a href=&quot;https://i.stack.imgur.com/kjq0J.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kjq0J.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-09-08T22:07:06.317" LastActivityDate="2015-09-16T08:41:28.663" Title="How does ignited gas spin the turbine?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;&lt;turbine&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20786" PostTypeId="1" CreationDate="2015-09-08T22:51:08.470" Score="43" ViewCount="5181" Body="&lt;p&gt;I spotted this recently. The distance and poor camera makes it really hard to determine what it is. Any help appreciated. Thanks.&lt;a href=&quot;https://i.stack.imgur.com/LyYt9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LyYt9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11143" LastEditorUserId="167" LastEditDate="2015-09-09T03:47:31.690" LastActivityDate="2015-09-10T10:24:32.937" Title="What is this delta-winged aircraft?" Tags="&lt;aircraft-identification&gt;&lt;plane-spotting&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20787" PostTypeId="2" ParentId="20785" CreationDate="2015-09-08T23:13:01.637" Score="3" Body="&lt;p&gt;I will attempt to answer the question though I'm not an engineer. Each spool (N1, N2 etc) has a compressor in the front and a turbine in the rear. Compressor is a set of rotor blades followed by stator vanes. This is a compression stage. Turbine has the opposite setup: stator vanes followed by rotor blades. They are either pure impulse turbines or impulse/reaction turbines. You may have a look in &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbine&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia&lt;/a&gt; to see the turbine working principle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the high speed combusted air that comes out of the combustion chambers put the turbine in motion. The turbine moves the shaft, the shaft moves the compressor, the compressor feeds the combustion chamber with compressed air and that cycle goes on and on for as long as there is fuel going in the chambers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a diagram of how is the turbine &quot;set to motion&quot;. Red arrows show how the airflow is guided from the nozzles to an impulsive turbine blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E5hoq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E5hoq.png&quot; alt=&quot;Impulsive turbine plan view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image source: own work&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stator vanes are convergent and the air coming through the resulting nozzles is accelerated. As the accelerated air impacts the curved rotor blades, they cause aerodynamic forces on them, similar to those caused on a wing (as others already said). These forces set the turbine to motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; Added image and corrected compressor and turbine stages description&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2015-09-16T08:41:28.663" LastActivityDate="2015-09-16T08:41:28.663" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20788" PostTypeId="2" ParentId="20786" CreationDate="2015-09-08T23:45:46.003" Score="78" Body="&lt;p&gt;&lt;em&gt;Took a fair bit of trial and error on the very vague registration on the port wing :)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;F-PDHV (D-Plane 1)&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Verhees_D-Plane_1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Verhees D-Plane 1&lt;/a&gt; is a Belgian homebuilt flying wing,&#xA;  designed by Verhees Engineering and supplied as plans for amateur&#xA;  construction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Picture from below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WcXtP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WcXtP.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.wingsovereurope.com/verhees_delta.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0DcKR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0DcKR.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;David Osborne/ Aeroprints &lt;a href=&quot;https://www.flickr.com/photos/aeroprints/9705932877/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="4067" LastEditDate="2015-09-10T10:24:32.937" LastActivityDate="2015-09-10T10:24:32.937" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="20790" PostTypeId="2" ParentId="20785" CreationDate="2015-09-09T00:27:20.997" Score="5" Body="&lt;p&gt;A turbine is a machine that extracts energy from a moving fluid and converts it into work. In the turbine blades, the air is expanded, which produces work. In many ways, the turbines are the opposite of compressors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/y1vd4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/y1vd4.jpg&quot; alt=&quot;Reaction turbine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Two_stage_reaction_turbine.jpg#/media/File:Two_stage_reaction_turbine.jpg&quot; rel=&quot;noreferrer&quot;&gt;Two stage reaction turbine&lt;/a&gt;&quot; by S.M.Yahya - Turbomachinery. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbines used in the aircrafts are axial flow turbines, which employ multiple stages to extract work from the air coming out of combustion chamber.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbines have two parts- the stationary nozzles (or stators) and  the moving rotors. The purpose of the nozzles is to turn the incoming flow so that that it impinges on the rotors at the correct angle, while the actual work is extracted out from fluid by the rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bnTLH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bnTLH.jpg&quot; alt=&quot;Velocity triangles&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Velocity_triangle_for_an_axial_turbine_stage.jpg#/media/File:Velocity_triangle_for_an_axial_turbine_stage.jpg&quot; rel=&quot;noreferrer&quot;&gt;Velocity triangle for an axial turbine stage&lt;/a&gt;&quot; by S.M.Yahya - Turbomachinery. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the rotors are 'turned' by the incoming fluid as shown above which produces work to rotate the shaft (which runs the compressor). In case of turbojet engines (and to some extent turbofan), the air pressure decreases, while the velocity increases. This provides the required thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main mechanism by which the turbine blades spin is that the flow &lt;em&gt;turns&lt;/em&gt; the rotor blades by hitting them, rather than any lift being produced.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-09T00:27:20.997" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20791" PostTypeId="1" AcceptedAnswerId="20797" CreationDate="2015-09-09T04:49:13.563" Score="3" ViewCount="2052" Body="&lt;p&gt;Can any variant of the HAL Lca Tejas (either the naval variant, the mark 1, mark 2 or later) perform &lt;a href=&quot;https://en.wikipedia.org/wiki/Pugachev&amp;#39;s_Cobra&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pugachev's Cobra&lt;/a&gt;?  If not, why?&lt;/p&gt;&#xA;" OwnerUserId="11145" LastEditorUserId="1696" LastEditDate="2018-04-13T16:25:39.060" LastActivityDate="2021-05-28T21:48:56.387" Title="Can the HAL Lca Tejas perform Pugachev's Cobra maneuver?" Tags="&lt;aircraft-performance&gt;&lt;fighter&gt;&lt;jet&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20792" PostTypeId="1" AcceptedAnswerId="20795" CreationDate="2015-09-09T04:54:09.337" Score="8" ViewCount="3446" Body="&lt;p&gt;I've heard (&lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/piperpa28.htm&quot;&gt;and read&lt;/a&gt;) that the PA-28 series has a laminar flow wing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Piper had a very thick airfoil that used laminar flow to assure that lift would be lost very slowly up to the stall. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;People &lt;a href=&quot;https://www.youtube.com/watch?v=h8AV7iH6HWk&quot;&gt;seem to pitch the Cherokee's wing as some sort of amazing safety and performance improvement&lt;/a&gt;. I've always understood that laminar flow wings had an abrupt, harsh stall, but offered reduced drag in cruise. I have a ton of early-Cherokee time on the 'Hershey Bar' wing, and its stall behavior is gentle and predictable, while its cruise speed is almost knot-for-knot on par with a Cessna 172 of comparable power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the PA-28 laminar flow wing just a marketing gimmick? &lt;strong&gt;If one were to put a Cherokee wing in a wind tunnel, would we see laminar flow?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-09-09T05:01:53.267" LastActivityDate="2015-09-12T10:50:05.140" Title="Does the Piper PA-28 Cherokee wing have laminar flow behavior?" Tags="&lt;aerodynamics&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20793" PostTypeId="2" ParentId="19590" CreationDate="2015-09-09T06:05:19.840" Score="1" Body="&lt;p&gt;You can fly any airplane with PPL even B737 if you own one. Well to fly B737 you will need IR, ATPL exams as it's multi crew airplane, MCC and TR. I don't know if it makes sense but you can put everything on PPL if you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You only have SEP so you only can fly SEP airplane. SEP is just any airplane with single piston engine. But CAA can decide to require TR for any aircraft if they consider it to be complex...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you get IR and TR and you can fly private jets without problem with PPL. But you see that to get everything you will need to know the same theory as for ATPL license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for K-10 Swift it's Ultra Light aircraft. Regulations differ by country I think. In my country CAA doesn't issue ultralight licenses but ultralight planes association.  General rule is that you will need difference training.  &lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="572" LastEditDate="2015-09-10T11:06:38.317" LastActivityDate="2015-09-10T11:06:38.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20794" PostTypeId="2" ParentId="20764" CreationDate="2015-09-09T06:20:42.947" Score="1" Body="&lt;p&gt;why would there be more value in keeping it than in scrapping it? That's simply not true.&lt;br/&gt;&#xA;The ONLY value would be for a few aviation enthousiasts who might be willing to pay the entrance fees for a museum where it would be put on display.&lt;br/&gt;&#xA;But at the time there was a glut in aircraft to put in museums. And of course most British museums at the time (and many even today) didn't charge admittance, they were run as public services for educational purposes.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;In a country with massive debt, recovering from a long and costly war, where raw materials are scarce, and aircraft to show off to the public are a dime a dozen, scrapping something that has no purpose and contains tons of valuable metals and other materials is the best thing to do, aviation buffs 70 years later who'd like to look at it and marvel at the folly of designers long ago to think something like that would be the future be darned.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-09-09T06:20:42.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20795" PostTypeId="2" ParentId="20792" CreationDate="2015-09-09T09:25:06.277" Score="14" Body="&lt;p&gt;Short answer: Yes. You would see laminar flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: It depends. In case of the wind tunnel it depends on the laminarity of the wind tunnel: Older designs had too much turbulence to allow for much laminarity. &lt;a href=&quot;http://history.nasa.gov/SP-4103/app-f.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;It was precisely for that reason that laminar flow was not well understood in the first decades of aviation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airfoil on the &lt;a href=&quot;http://www.basicaircraft.com/piper-aircraft.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cherokee&lt;/a&gt; is the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=naca652415-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA $65_2415$&lt;/a&gt;, and its Reynolds number in normal operation is in the single digit millions. The laminar bucket is ideally between the lift coefficients from 0.2 to 0.6, and the Reynolds number is low enough to allow for laminar flow. When you approach stall, however, the upper side has a pronounced suction peak near the nose which lets the flow rapidly transition to turbulent flow right after the peak. Laminar flow can only be found on the lower side (if surface roughness is low enough).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure distribution over the rear 50% of the airfoil shows a constant pressure rise, so the onset of stall is marked by flow separation which starts at the trailing edge and slowly marches forward with increasing angle of attack. This leaves the suction area in the forward part unperturbed and keeps lift nearly constant around stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrast this with the stall behavior of the 5-digit NACA series, which can only be described as nasty. Stall is marked by flow separation right past the suction peak at the nose, and the lift coefficient suddenly drops by at least 0.2 counts when the airfoil stalls. Only some laminar airfoils have a similarly harsh stall behavior; this happens mostly when their designers were too ambitious and achieved the pressure rise with a &lt;a href=&quot;http://www.cfd-online.com/Wiki/Stratford&amp;#39;s_separation_criterion&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stratford pressure distribution&lt;/a&gt;. This is a distribution which keeps the separation margin constant along its length, and at stall it is exceeded everywhere at once, creating a sudden, large separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956?s=24%7C0.0620#16956&quot;&gt;well-designed laminar airfoil&lt;/a&gt; has a gentle stall behavior. Its lift coefficients with laminar flow are normally quite a bit away from stall, and its stall characteristics can be tailored independently from the region with laminar flow. Using a NACA $65_2415$ instead of a NACA 23015 is not a marketing gimmick, but a sound choice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the performance: As long as the plane has a fixed landing gear, the laminarity of the wing will have little effect on top speed - the parasitic drag of all those things sticking out from the airframe will dominate drag. In addition, &lt;a href=&quot;http://wp1113056.server-he.de/ABL/20-forschung/laminarfluegel/laminarfluegel_en.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;the higher the Reynolds number in flight is, the shorter the laminar flow will be before it transitions to turbulent flow&lt;/a&gt;, so the effect is much reduced at higher speed. Also, the way the wing is built makes a lot of difference, because every rivet head and every gap will create a wedge of turbulent flow behind it.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-12T10:50:05.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20797" PostTypeId="2" ParentId="20791" CreationDate="2015-09-09T11:32:35.880" Score="13" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&lt;p&gt;With that delta wing shape it will have pitch control problems at higher angles of attack. The Cobra maneuver requires a small pitch-down moment over the post-stall region up to 110° angle of attack. I very much doubt that this wing planform will have such pitch characteristics, and without thrust vector control a docile pitch behavior is a prerequisite for the Cobra maneuver.&lt;/p&gt;&#xA;&lt;p&gt;In the development of the LCA a high lift coefficient without leading edge devices was the main goal of the wing design. It should be able to operate in the vicinity of flocks of birds - birdstrike is a real risk on many Indian Air Force bases. At the same time, the small aircraft should be able to fly supersonically, which lead to the double-delta wing as the best way to achieve both goals, and poor post-stall pitch response had to be accepted.&lt;/p&gt;&#xA;&lt;p&gt;When HAL switched from MBB to Dassault for technical support, leading edge devices were added in order to fulfil the take-off and landing requirements. Post-stall flight was not seriously considered at any point in the development.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-05-28T21:48:56.387" LastActivityDate="2021-05-28T21:48:56.387" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="20798" PostTypeId="1" AcceptedAnswerId="20832" CreationDate="2015-09-09T13:48:10.583" Score="14" ViewCount="16301" Body="&lt;p&gt;I know that &lt;a href=&quot;https://en.wikipedia.org/wiki/National_Advisory_Committee_for_Aeronautics&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA&lt;/a&gt; is famous for its ducts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3e/Ferrari_F40_in_IMS_parking_lot.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3e/Ferrari_F40_in_IMS_parking_lot.jpg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3e/Ferrari_F40_in_IMS_parking_lot.jpg&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Gratuitous Ferrari F-40 from &lt;a href=&quot;https://en.wikipedia.org/wiki/NACA_duct&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;. Mmmm... pretty...&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also well known for its airfoils, and many planes in the early years of aviation used NACA designed airfoils for their wings (for example the Piper Cherokee referenced &lt;a href=&quot;https://aviation.stackexchange.com/questions/20792/does-the-piper-pa-28-cherokee-wing-have-laminar-flow-behavior&quot;&gt;here&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f9/PiperPA-28-236DakotaC-GGFSPhoto4.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f9/PiperPA-28-236DakotaC-GGFSPhoto4.JPG&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f9/PiperPA-28-236DakotaC-GGFSPhoto4.JPG&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Piper PA-28 also courtesy of &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do current aircraft manufacturers still use stock NACA airfoil designs, start with a NACA standard design then modify it to meet needs, or are the airfoils completely &lt;a href=&quot;https://en.wikipedia.org/wiki/Bespoke&quot; rel=&quot;nofollow noreferrer&quot;&gt;bespoke&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking about the major airliner manufacturers like &lt;a href=&quot;http://www.boeing.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt; &amp;amp; &lt;a href=&quot;http://www.airbus.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus&lt;/a&gt;, regional jet builders like &lt;a href=&quot;http://www.embraer.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Embraer&lt;/a&gt;, as well as private/GA companies like &lt;a href=&quot;http://cessna.txtav.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna&lt;/a&gt;, &lt;a href=&quot;http://www.gulfstream.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gulfstream&lt;/a&gt;, and, of course &lt;a href=&quot;http://www.piper.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper&lt;/a&gt;. Information on the (few, dozens, hundreds?) of other aircraft manufacturers (and kit designers) that don't pop to the top of my head is also welcome and appreciated.&#xA;&lt;hr&gt;&#xA;Thinking about this further, I realize it could quickly devolve into a very broad &lt;code&gt;this aircraft uses a NACA standard wing&lt;/code&gt;, &lt;code&gt;that one doesn't&lt;/code&gt; list. That's not really my intent. A simple &lt;code&gt;yes, this aircraft/wing from 5-10 years ago uses a NACA standard&lt;/code&gt; would answer the question completely, as would a &lt;code&gt;the last one I'm aware of is from 35+ years ago&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the use of &quot;modern&quot; is rather vague as the Boeing 757 certainly &lt;em&gt;feels&lt;/em&gt; &quot;modern&quot; (having been launched in 1982) but has been out of production since 2004, while the 747 started production in 1969 and is still being built. If someone wants to jump in to help define &quot;modern&quot;, I'd take no offense.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-09-10T12:46:55.770" Title="Are NACA airfoils used in modern aircraft design?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;airfoil&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20799" PostTypeId="1" AcceptedAnswerId="30675" CreationDate="2015-09-09T13:56:43.823" Score="27" ViewCount="10659" Body="&lt;p&gt;We all know what &quot;taxi&quot; means to general public -- a car which carries you from A to B in exchange for your paying a fare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Taxi&quot; also means &lt;em&gt;to drive an aircraft on the ground&lt;/em&gt;. Why do we call it that? What's the reason &amp;amp; history behind the term?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="97" LastEditDate="2015-09-09T18:40:57.533" LastActivityDate="2016-08-12T13:17:45.430" Title="Why do we call moving an aircraft on the ground &quot;taxi&quot;?" Tags="&lt;aviation-history&gt;&lt;terminology&gt;&lt;taxiing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20800" PostTypeId="2" ParentId="20799" CreationDate="2015-09-09T14:08:08.443" Score="12" Body="&lt;p&gt;This &lt;a href=&quot;http://www.etymonline.com/index.php?term=taxi&quot;&gt;online etymological site&lt;/a&gt; suggests that an airplane moves slowly across the field in a similar fashion to how a taxi-cab driver would slowly make his way down a block looking for fares, and the term is borrowed from that behavior.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-09-09T14:08:08.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20801" PostTypeId="2" ParentId="20798" CreationDate="2015-09-09T14:17:28.523" Score="7" Body="&lt;p&gt;NACA airfoils are used still used in aircraft, though most of the airfoils used are modified in some way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the Cessa uses either pure or modified NACA airfoils in most of its Cessna Citation jets, though newer models tend to use Cessna's own airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_Citation_V&quot; rel=&quot;nofollow noreferrer&quot;&gt;Citation V&lt;/a&gt; uses modified NACA 23014 airfoil at the root and modified NACA 23012 at the tip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R1jU6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R1jU6.jpg&quot; alt=&quot;Cessna Citation&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Cessna_uc-35a_citation_560_ultra_v_arp.jpg#/media/File:Cessna_uc-35a_citation_560_ultra_v_arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna uc-35a citation 560 ultra v arp&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Arpingstone&quot;&gt;Adrian Pingstone&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recent ones, like the 750 Citation X uses Cessna's own Cessna 7500 airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing, on the other hand has been mostly using its own airfoil designs from day one, though it has 'borrowed' ideas from NACA series (like supercritical design)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the military side, the F22 Raptor uses a modified NACA 6 series airfoil. According to &lt;a href=&quot;http://www.pdas.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Public Domain Aeronautical Software&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;F-22 uses a uncambered 64A section with 5.92 percent thickness at the root and 4.29 percent thickness at the tip&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For a detailed list please see &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/aircraft.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Incomplete Guide to Airfoil Usage&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-10T12:46:55.770" LastActivityDate="2015-09-10T12:46:55.770" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20802" PostTypeId="2" ParentId="20799" CreationDate="2015-09-09T15:02:46.643" Score="3" Body="&lt;p&gt;I'll throw a thought in the mix although the term most likely pre-dates this: When you are running a plane on the tarmac the &quot;meter&quot; is literally running since the engines are on. Much like the meter that starts running when you get in a taxi cab. There is no worse feeling than renting a plane for a nice day of flying and getting stuck in a departure line watching the Hobbs slowly tick on while you sit there hopelessly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly the history of the word &quot;taxi&quot; as we use it for cars dates from the word &lt;a href=&quot;https://en.wikipedia.org/wiki/Taximeter&quot; rel=&quot;nofollow&quot;&gt;taximeter&lt;/a&gt; the device installed in taxicabs to measure fare. Which comes from the french taxer-mètre. The evolution may come from the fact that the ground operations of the aircraft are part of the ticket which you paid for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Its a long shot but its worth a thought) &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-08-12T13:17:45.430" LastActivityDate="2016-08-12T13:17:45.430" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20803" PostTypeId="1" AcceptedAnswerId="20807" CreationDate="2015-09-09T15:54:54.127" Score="32" ViewCount="8014" Body="&lt;p&gt;Runway 18 at &lt;a href=&quot;https://en.wikipedia.org/wiki/Frankfurt_Airport&quot; rel=&quot;noreferrer&quot;&gt;Frankfurt Airport&lt;/a&gt; is one example of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/18988/are-there-runways-that-are-numbered-only-on-one-side?rq=1&quot;&gt;runway which is numbered on only one side&lt;/a&gt;. Aircraft can only takeoff in the 18 direction, and cannot takeoff in the 36 direction, nor land in any direction except in an emergency situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason behind it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PMr4H.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PMr4H.jpg&quot; alt=&quot;Diagram of Frankfurt Airport&quot;&gt;&lt;/a&gt;&lt;BR&gt;Thomas Römer/OpenStreetMap data [&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/2.0&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 2.0&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File%3AFrankfurt-Main_Airport_Map_DE.png&quot; rel=&quot;noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="14897" LastEditDate="2017-05-02T14:27:08.200" LastActivityDate="2019-04-22T14:06:08.377" Title="Why can't runway 18 at Frankfurt Airport accept takeoffs or landings in the opposite direction?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20804" PostTypeId="2" ParentId="20791" CreationDate="2015-09-09T16:04:52.370" Score="5" Body="&lt;p&gt;No known variant of the &lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;noreferrer&quot;&gt;HAL Tejas&lt;/a&gt; can perform the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pugachev%27s_Cobra&quot; rel=&quot;noreferrer&quot;&gt;Cobra Maneuver&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is for the simple reason that the aircraft was not designed nor was it expected to perform such a maneuver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a Cobra, the plane suddenly raises the nose to the veritical position (or beyond, usually 90$^{\circ}$ to 120$^{\circ}$) before dropping it back to the normal flight, maintaining more or less the same altitude through the entire maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CtBp5.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CtBp5.png&quot; alt=&quot;Cobra Maneuver&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.saddahaq.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cobra maneuver is a dynamic maneuver to a high angle of attack, beyond any equilibrium or trim point. Pitching angular momentum carries the aircraft to a peak angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;em&gt;Airplane Stability and Control&lt;/em&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Cobra is started from unstalled flight with a rapid application of full nose-up control, which is held up to the maximum angle of attack point, about 90 degrees. Control is neutralized for the recovery, assuming that the airplane has a negative or nose-down pitching moment at that point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As can be seen from above, the performance of this maneuver requires control (and a pitch down moment at high aoa) in the high angle of attack region, though it can be done with conventional controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tejas is not designed with such characteristics. The main thrust in designing of Tejas was to get a 4(+) generation aircraft with relaxed static stability. Tejas is basically a replacement for Mig-21 (a process which is not going very well), and as such the main design goals were to produce a small, supersonic aircraft to excel in interception/air superiority role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Towards this, the compound delta wing was chosen because it was small and lightweight compared to other designs available. Though the wing has good high-alpha characteristics and aircraft has good maneuverability, post-stall maneuvering was never considered for this fighter. As such, no variant of Tejas has the capability to do post-stall maneuvering and there are no plans to include them in the future.  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-09T16:04:52.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20805" PostTypeId="2" ParentId="20803" CreationDate="2015-09-09T16:13:22.927" Score="5" Body="&lt;p&gt;looking at the chart, you can see buildings right past the treshold on the opposite end. Taking off to the north (or landing from the north) would put you dangerously low over those buildings, not a safe situation at all.&lt;br/&gt;&#xA;Also, there are no doubt very strict noise restrictions in place which ban overflights of the towns and city districts just north of the airport, further restricting the usefulness of maintaining navigation aids and other things needed to make it an operational runway in both directions.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-09-09T16:13:22.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20806" PostTypeId="2" ParentId="20803" CreationDate="2015-09-09T16:15:39.367" Score="3" Body="&lt;p&gt;If you see the runway orientation, it is clear that any landing in the runway 18 (Runway West) will interfere with air traffic in the other runways (Runways North, 07C/25C  and South, 07R/25L).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same thing goes for takeoffs to the north in that runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason the runway is used only for takeoffs in southbound direction.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-09T16:15:39.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20807" PostTypeId="2" ParentId="20803" CreationDate="2015-09-09T16:33:57.613" Score="38" Body="&lt;p&gt;Let us consider the operations other than takeoff on runway 18.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Takeoff Runway 36&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are buildings not far off the departure end and directly after the end of the runway is a movement area and ramp.  To safely takeoff they would have to clear that area and probably replace all the concrete with crushable concrete (more on this later).  The buildings probably post obstacle clearance issues for engine out climb performance.  The east-west runway north of 36 would have conflicting traffic and would have to be carefully sequenced.  Lastly, that purple area to the north of the runway is probably a noise sensitive area you aren't allowed to fly over at low altitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landing Runway 18&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You approach over a noise sensitive area, cross over operations on the northern east-west runway, overfly a building at extremely low levels (wheels on the roof) and have to make sure there are not airplanes on the ramp between the building and runway.  Landing short would be nothing short of disastrous and every landing would be a risky operation with the close proximity of airplanes and buildings.  Glideslope services would probably not be available due to ground obstacles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landing Runway 36&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the least problematic approach.  The problem is in missed approaches and long landings.   There is no safety area at the end of 36 and a runway excursion past the end of the runway would be catastrophic.  To mitigate this they could re-pour the ramp concrete with crushable safety concrete, but that would probably make using ramp and building unsuitable.  If traffic goes around they conflict with aircraft on the northern east-west runway and have a noise sensitive area to deal with.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In comparison to the above, taking off to the south only requires a blast fence just north of the runway to protect the ramp and building from jet blast.  There are no logistic issues in aircraft movement on the ramp and the building is not in danger of being hit.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-09T16:33:57.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20808" PostTypeId="1" AcceptedAnswerId="20814" CreationDate="2015-09-09T18:47:17.833" Score="7" ViewCount="447" Body="&lt;p&gt;I know the crew usually decides ahead of time which pilot is to be PF for each phase of the flight. If, when they arrive at their destination they discover a considerable crosswind component, does that ever change that decision? It seems that the upwind seat would have a considerable visual advantage. (or maybe that isn't true?) Also, do airlines have guidelines on things of that sort requiring that the PIC fly the landing?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="19" LastEditDate="2017-08-10T09:55:20.297" LastActivityDate="2017-08-10T09:55:20.297" Title="Do crosswinds affect which pilot lands the plane?" Tags="&lt;landing&gt;&lt;regulations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20809" PostTypeId="1" AcceptedAnswerId="20810" CreationDate="2015-09-09T19:37:48.327" Score="14" ViewCount="5185" Body="&lt;p&gt;The NTSB recently released its final report of &lt;a href=&quot;http://www.bostonglobe.com/metro/2015/09/09/ntsb-hold-hearing-wednesday-hanscom-crash/rljZVKb0wPh13xpQKzck7M/story.html&quot;&gt;a crash at Hanscom field&lt;/a&gt; (KBED) in Bedford, MA. The short of it is that the pilot tried to rotate with the gust lock engaged, preventing the plane from lifting off. It rolled past the runway and finally crashed into a ditch, where it burst into flame, killing everyone on board. (I should say that although I've flown in a small 4-seater a few times, I'm not a pilot &amp;mdash; so please forgive me if I misused some terminology.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thought I had is that if the landing gear had been destroyed at the end of the runway, the crash could have been a lot less severe. In particular, I was thinking that a small wall could have been designed to knock the gear out, making the plane start skidding on its belly and presumably coming to a stop much sooner. It wouldn't be exactly &lt;em&gt;safe&lt;/em&gt;, but it seems like it would be safer than relying on just the gear's braking power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does such a device exist at any airports? And if not, has it been considered and rejected for some reason?&lt;/p&gt;&#xA;" OwnerUserId="7793" LastEditorUserId="5517" LastEditDate="2015-09-10T15:36:07.293" LastActivityDate="2015-09-10T20:23:37.100" Title="Could a runway include a safety device to destroy a plane's landing gear?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20810" PostTypeId="2" ParentId="20809" CreationDate="2015-09-09T19:47:03.717" Score="37" Body="&lt;p&gt;There is indeed such a system installed at some airports. It is called an &lt;a href=&quot;https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system&quot; rel=&quot;noreferrer&quot;&gt;engineered materials arrestor system (EMAS)&lt;/a&gt;. Incidents such as &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=4&amp;amp;LLID=56&amp;amp;LLTypeID=2&quot; rel=&quot;noreferrer&quot;&gt;Southwest 1248&lt;/a&gt; have shown the potential safety issues of runway overruns, as you have pointed out. The EMAS solution uses a pad of special material at the end of the runway, designed to allow landing gear to sink into the material. The landing gear is not ripped off, but as the gear travels through the material, the plane is slowed down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Destroying the gear is not a desirable option. Although the gear on airliners is designed to safely separate from the aircraft, there is still the potential for damaging fuel tanks or other structure. The aircraft will also be even less controllable after the loss of landing gear. If a small aircraft is not going very fast, a small wall could cause it to flip over, worsening the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the crash you referenced, the aircraft was traveling very fast at the end of the runway, and an EMAS may not have been sufficient to stop the plane. An EMAS typically has a max entry speed of &lt;a href=&quot;http://www.skybrary.aero/index.php/Engineered_Materials_Arresting_System_%28EMAS%29&quot; rel=&quot;noreferrer&quot;&gt;70 knots&lt;/a&gt;, so in incidents like the one linked from the question, this kind of system may not completely prevent a fatal incident. Since the aircraft's gear must break through the material, lighter aircraft may not be stopped as effectively. However, &lt;a href=&quot;http://articles.latimes.com/2006/oct/14/local/me-burair14&quot; rel=&quot;noreferrer&quot;&gt;small aircraft have been stopped&lt;/a&gt; with such a system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RnHjI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RnHjI.jpg&quot; alt=&quot;Landing gear in EMAS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=13754&quot; rel=&quot;noreferrer&quot;&gt;The FAA is looking&lt;/a&gt; at places where these systems could be useful, with a focus on runways that cannot have the recommended 1,000 foot safety area at the end. The runway safety area (RSA) is the best option for a safety buffer at the end of a runway, providing extra distance for an aircraft to stop. The article above notes that the EMAS at Burbank airport took $4 million to install, and that is a fairly small airport that doesn't usually see anything larger than a 737. Any overrun will incur certain recovery costs, but an EMAS will need to be repaired after any overrun or accidental damage, possibly closing the runway, and will be less effective until repairs are completed. Airports must weigh all of their options for providing a safe facility.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-09-10T14:50:43.037" LastActivityDate="2015-09-10T14:50:43.037" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20811" PostTypeId="2" ParentId="11936" CreationDate="2015-09-09T19:47:39.980" Score="6" Body="&lt;p&gt;More or less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is the &quot;critical Mach number&quot; of the wing planform. Most wings have a curved upper surface, which forces the air moving over that side of the wing to move faster, lowering its pressure, producing lift. At a forward airspeed of the entire airfoil near but less than Mach 1, the airflow over the top of the airfoil exceeds Mach 1 as it passes over the wing's leading edge, then slows again to subsonic speeds around the crest of the wing. This &quot;transsonic&quot; airflow increases drag on the aircraft at airspeeds between the critical Mach number and the speed at which all airflow over every surface of the aircraft is supersonic (when transsonic airflow is no longer a problem, but other leading-edge and wake drag forces come to dominate total drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial airliners sometimes exceed the critical Mach number of their wings, producing a shockwave that is visible either as a mirage-like optical disturbance, or if conditions are just right, a vapor plume:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aJG6E.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aJG6E.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter jets accelerating past Mach 1 commonly create &quot;vapor cones&quot; beginning at the transsonic border of their airflow, caused when the high variance in air pressure at this transsonic shockwave border forces water vapor to condense:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iWSCg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iWSCg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The critical Mach number is determined by the design of the planform. Wings with thicker cross-sections produce more lift for less area (and more induced drag from that lift) and generally also have a higher angle of attack (meaning, all other things being equal, a lower stall speed), but the tradeoff is a lower critical Mach number. The converse is true for a thinner cross-section; critical Mach number is increased, while lift, drag and critical AoA are reduced.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-09-09T19:47:39.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20812" PostTypeId="2" ParentId="20809" CreationDate="2015-09-09T20:22:16.290" Score="15" Body="&lt;p&gt;The short answer is yes; EMAS and other arresting systems up to and including nets are in place at many airfields of varying sizes. The most common AFAIK is a gravel pit, aka the litterbox; it's filled with sugar sand, a lightweight gravel like pumice rock or a manufactured alternative, that yields and/or crushes much like EMAS panels under the weight of landing gear to increase rolling resistance and stop a plane that rolls off the end of the runway. They are not designed to damage the plane such as by snapping the gear off (though such damage is often par for the course), as that would actually take away the plane's most effective stopping method, its brakes and rubber tires, instead forcing the plane to skid to a stop on its slick underbelly. They're also definitely not designed or intended to stop a plane barreling off the end of the runway under full engine power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no safety mechanism in existence that can 100% replace the human brain in ensuring safe performance of inherently dangerous tasks. In the accident you refer to, several basic yet critical checklist steps were skipped that would have indicated the presence of a gust lock, among them visually inspecting and checking for free movement of control surfaces during the walkaround, and the stick/rudder movement check during runup to ensure the flight controls are unhindered and properly manipulate the control surfaces. The NTSB places the blame for this accident squarely on the failure to perform basic preflight checks prior to the attempted takeoff. Preflight checks exist for this exact reason; to prevent pilots attempting to fly a plane they will not be able to operate safely due to some mechanical defect or hindrance, whether that's a gust lock, water in the fuel tanks, a bird nesting in the engine cowling, or a bullet hole in the rudder. The walkaround is literally the first thing a new civilian pilot learns on their first flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There really is no such thing as a foolproof system; fools are too ingenious. The pilot(s) of an aircaft are ultimately responsible for the safe operation of that aircraft, because it's ultimately their lives depending on a safe flight. That's why it's part of their job to do the preflight checks. If a pilot doesn't value his own life enough to do something as basic as this, he shouldn't be anywhere near an aircraft, because when his lack of regard leads to the loss of his life, it's very unlikely his life will be the only one lost.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-10T20:23:37.100" LastActivityDate="2015-09-10T20:23:37.100" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20813" PostTypeId="2" ParentId="20808" CreationDate="2015-09-09T20:25:29.320" Score="0" Body="&lt;p&gt;There is almost always some crosswind component on every landing if there is any wind at all.  Therefore the pilot who is making the landing, either left or right applies the necessary corrections to make a successful landing. &#xA;Crosswind landings is taught to the beginning pilot early in his initial training to cope with the problem.  Each class of aircraft has different approach and touchdown methods to cope with the cross wind problem. &lt;/p&gt;&#xA;" OwnerUserId="11154" LastActivityDate="2015-09-09T20:25:29.320" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="20814" PostTypeId="2" ParentId="20808" CreationDate="2015-09-09T21:01:19.713" Score="3" Body="&lt;p&gt;Never ask a question with &quot;ever&quot; in it - because the answer will very rarely be no!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example - if one pilot is training, then while they may have planned to do the landing reality might dictate that they have to hand over the controls to the instructor. I'm sure the same will apply to type ratings or differences training - nobody is going to let you have a crack at a severe crosswind landing during your first front-seat flight in an A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, flying schools will often have strict crosswind limits and some may not grant you full &quot;As Pilot Operating Handbook&quot; privileges until you have [x] number of hours AFTER your test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words - you may have two qualified pilots, but only one of which is allowed to land the plane!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I'm being deliberately pedantic - I suspect you're focussing more on commercial, multi-crew operations rather than two pilots who happen to be in one aircraft and I'm not qualified to answer that bit!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not aware of any requirement to take seat position into account, however.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-09-09T21:01:19.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20815" PostTypeId="1" AcceptedAnswerId="20839" CreationDate="2015-09-09T21:36:00.057" Score="8" ViewCount="11294" Body="&lt;p&gt;From watching planes land at DIA on Flightradar24, none seem to ever land on 16R (longest runway in the US at a length of 16,000 ft), but instead land on a runway 4,000 ft shorter such as runway 16L (12,000ft). So why do even large planes like the 747 not land on the longer runway to have an easier landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dEQ2p.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dEQ2p.jpg&quot; alt=&quot;Airport diagram showing location of 16R/34L&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="2" LastEditDate="2015-09-14T16:06:03.533" LastActivityDate="2019-02-14T02:30:05.050" Title="Why is Denver International Airport runway 16R/34L rarely used?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20816" PostTypeId="1" AcceptedAnswerId="20833" CreationDate="2015-09-09T23:27:10.217" Score="16" ViewCount="3292" Body="&lt;p&gt;The first airliner to ever break the sound barrier was the DC-8, doing so in a &lt;a href=&quot;http://www.airspacemag.com/history-of-flight/i-was-there-when-the-dc-8-went-supersonic-27846699/?no-ist&quot;&gt;semi-famous dive from 52,000' to 35,000'&lt;/a&gt; over the Edwards test range on August 21, 1961.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could this supersonic dive be planned and reproduced by a suitable flight test crew in a more modern jet transport aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2021-04-05T16:09:16.730" Title="Could a test crew replicate the 1961 DC-8 supersonic dive in a more modern airliner?" Tags="&lt;airliner&gt;&lt;supersonic&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20818" PostTypeId="1" AcceptedAnswerId="20822" CreationDate="2015-09-09T23:37:36.130" Score="2" ViewCount="344" Body="&lt;p&gt;Assume you have a large airliner such as a 747, and you're taking off from a place, such as &lt;a href=&quot;https://aviation.stackexchange.com/questions/7853/can-a-747-land-at-ovda&quot;&gt;Ovda&lt;/a&gt;, where you can't load enough fuel to make it to your destination without stopping somewhere along the way.  From all the airports along the route to your destination, what criteria are used to determine what a suitable &quot;somewhere&quot; to stop at for fuel is, assuming that runway size and fuel availability have already been filtered for?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-09-10T09:49:33.183" Title="What criteria make an airport suitable for a technical stop for a large airliner?" Tags="&lt;airport&gt;&lt;flight-planning&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20819" PostTypeId="2" ParentId="8488" CreationDate="2015-09-09T23:40:12.127" Score="2" Body="&lt;p&gt;An early use of &quot;Dutch rolls&quot; in aeroplaning is 1910:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Fancy aeroplaning was on the programme at the Harvard Aviation Field the next day, with Ralph Johnstone and Walter Brookins as the star performers. They demonstrated their skill with the biplanes until Wilbur Wright feared for their safety and ordered them to desist. Johnstone's favorite stunt was to indulge in steep volplanes, shutting his engine almost completely off and  floating lazily for a moment on an even keel, then suddenly shooting down through space until het almost touched the ground. Then would follow a &lt;strong&gt;series of Dutch rolls&lt;/strong&gt; as he swooped up and down close to earth.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conquest of the Air by Airships and Other Flying Machines, Jay Henry Mowbray, 1910. &lt;a href=&quot;https://books.google.nl/books?id=pp5BAAAAYAAJ&amp;amp;q=%22Dutch%20rolls%22&amp;amp;dq=%22Dutch%20rolls%22&amp;amp;hl=nl&amp;amp;sa=X&amp;amp;ved=0CC4Q6AEwAmoVChMI7I2IqIzrxwIVriPbCh0cegSx&quot; rel=&quot;nofollow&quot;&gt;(Link)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11156" LastEditorUserId="11157" LastEditDate="2015-09-10T00:01:12.523" LastActivityDate="2015-09-10T00:01:12.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20822" PostTypeId="2" ParentId="20818" CreationDate="2015-09-10T00:20:22.647" Score="5" Body="&lt;p&gt;Some factors might be: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Price of fuel at the various airports?&lt;/li&gt;&#xA;&lt;li&gt;Landing fees?&lt;/li&gt;&#xA;&lt;li&gt;Are any of the airports so busy that you might have to hold waiting for landing clearance? (You don't want to plan a fuel stop at LHR).&lt;/li&gt;&#xA;&lt;li&gt;Can you expect long taxis in some places? (All other things being equal, a single runway with a ramp next to it is better news than something like Schiphol or O'Hare).&lt;/li&gt;&#xA;&lt;li&gt;If you're carrying passengers, are some of the airports in countries with significantly more cumbersome immigration rules applying to technical stops than others? Some may want airport transit visas from passengers of certain nationalities even if they don't disembark.&lt;/li&gt;&#xA;&lt;li&gt;Political considerations such as the ones mentioned by Terry in the comment.&lt;/li&gt;&#xA;&lt;li&gt;And, of course, the total expected fuel burn for the two legs, which will depend on your refueling points. Your operations department will make concrete calculations for a number of likely stops, and weather has an influence on top of geography. If you have several possible airports that all happen to be right on the shortest path between your origin and destination, the math will tend to favor a refueling stop roughly in the middle -- this will minimize the total cost-of-lifting-enough-fuel-for-the-rest-of-the-leg.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Finally, if you're planning a recurring scheduled flight, will any of the options provide a business opportunity to take on some extra passengers on days where the demand from the actual origin is low?&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-09-10T09:49:33.183" LastActivityDate="2015-09-10T09:49:33.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20823" PostTypeId="2" ParentId="20815" CreationDate="2015-09-10T00:29:34.497" Score="4" Body="&lt;p&gt;What time are you usually watching radar?&lt;br&gt;&#xA;Just a guess, but the following paragraph from &lt;a href=&quot;http://www.flydenver.com/sites/default/files/rules/210_noise.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; would suggest noise abatement procedures. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Runways 34L and 34R :  Aircraft will be assigned headings of  355 to 010 degrees.   Intersection departures on  Runway 34L permitted if  user has  signed an agreement with the City and County of  Denver regarding terms of use .  The City may request that FAA stop allowing  intersection  departures if  the City determines that use of the procedure is resulting in detrimental noise impacts   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://business.flydenver.com/community/noise/reports/landuse_contours.pdf&quot; rel=&quot;nofollow&quot;&gt;This map&lt;/a&gt; shows you might not want to buy a house off the north end of the runway!&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-09-10T00:29:34.497" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20824" PostTypeId="1" CreationDate="2015-09-10T01:26:35.693" Score="10" ViewCount="691" Body="&lt;p&gt;I thought of this while coming in on a bumpy flight into Memphis, TN. The pilot of the airliner brought in the aircraft nicely, despite having to fight it quite a bit during the slowest portion of the approach. Now, Memphis is fairly flat, and the airport isn't near any large buildings so this isn't too much of a problem, but how do pilots practice bad weather approaches and takeoffs? It's kind of dicey to drop a newbie pilot into swirling bad weather, and I know as the aircraft gets smaller handling rough weather becomes harder. Is it done purely through simulators or do they use training flights where they intentionally fly during really rough weather? How does this training differ between general aviation and airline pilots? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd imagine flight simulators are good up to a point, but may not simulate all of the bad emergencies that could happen in bad weather (choppy crosswinds, hail, rain, lightning, etc.) so to train properly one would have to go up on training flights. However, I know that is very dangerous, and probably expensive, so it wouldn't be preferable. What platforms do current pilots use to get proficient at bad weather flying?&lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2015-09-10T03:06:23.270" Title="How does one train for making landings and takeoffs in bad weather?" Tags="&lt;flight-training&gt;&lt;general-aviation&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20825" PostTypeId="1" AcceptedAnswerId="20836" CreationDate="2015-09-10T01:41:53.473" Score="6" ViewCount="538" Body="&lt;p&gt;I was reading that in India regulators have specified certain airports at which the FO is not allowed to take off or land.    &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Pilot-in-Command shall not authorise a Co-pilot to effect supervised take-off or landing when TODA/LDA is  marginal. A margin of at least 1000 feet must be ensured.  Critical airfields,  [Mangalore, Port Blair, Leh, Agartala, Lengpui, Shimla &amp;amp; Kullu airports]  are specifically excluded for supervised take off and landing.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a matter of fact they have &lt;a href=&quot;http://dgca.nic.in/aic/aic09_07.pdf&quot;&gt;several limits&lt;/a&gt; in place where 'supervised takeoffs and landings' are not allowed and the PIC must fly the plane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this unique to India or are limits on FO's common?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-06-17T03:45:18.947" Title="How common are regulations limiting when the FO can be PF?" Tags="&lt;regulations&gt;&lt;crew&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20827" PostTypeId="2" ParentId="20824" CreationDate="2015-09-10T02:33:46.983" Score="8" Body="&lt;p&gt;Your question has two components: 1) how do pilots train for adverse conditions and 2) how do pilots stay fresh on adverse conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you said, smaller airplanes (really, slower airplanes) are hardest, because the wind speed is a larger percentage of the airplane's flying speed. There are no real simulators for small airplanes: we learn by going out and doing. When you first learn to fly, your instructor makes sure you can handle crosswinds and gusts. With the Instrument Rating comes more adverse weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you have learned the techniques (and stay proficient by practicing regularly), faster airplanes and higher winds are not really a problem -- the same techniques apply, and in any case you will have a more experienced pilot or instructor helping you along.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I must call out your use of &quot;newbie pilot&quot; -- I hope you're not implying that airline pilots are newbies in any sense of the word. Before you can even hope to get an airline job you've already experienced bad weather in marginal airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, staying proficient: this is where transport airplanes (airlines) are very different from the small airplanes. The airlines' pilots practice regularly on simulators that really can duplicate just about any kind of weather you'd fly in. Pilots of small airplanes though... the simulators can't do that, and we practice in the real world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that said, a passenger's idea of what makes a good landing is very different from a pilot's! A passenger thinks a smooth touchdown is what makes a good landing. For a pilot, a good landing means a stable and controlled approach followed by an appropriate touchdown that maximizes safety -- in gusty crosswinds a firm touchdown is much safer than a greaser.&lt;/p&gt;&#xA;" OwnerUserId="9826" LastActivityDate="2015-09-10T02:33:46.983" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20828" PostTypeId="2" ParentId="20824" CreationDate="2015-09-10T03:06:23.270" Score="1" Body="&lt;p&gt;Besides simulator, pilots usually pair up with one another in airline operations. There is the Captain and the First Officer, the Captain (most of the time) being more experienced. The First Officer can observe the decision making process of the Captain, e.g. why do we use a certain flaps setting, why is it ok to pass through that storm or should we abort the landing, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Storms, or snows, while not uncommon, are not something you see everyday. That's how experienced is passed onto new pilots: by flying with a more experienced pilot who has seen these weather many times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as skills is concerned, there aren't many new flying skills in an airliner compared to a small aircraft, except for maybe a few tips or tricks dependent on that specific model. Simulators can provide some quite extreme weather for training; but unless you've been super lucky, you are likely to have encountered unfavorable weather on your way to becoming an airline pilot.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-09-10T03:06:23.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20829" PostTypeId="2" ParentId="20798" CreationDate="2015-09-10T03:16:10.817" Score="1" Body="&lt;p&gt;The Cessna 172R uses a modified NACA 2412 airfoil and has been in production since 1956 to the present. This also substantiates the excellent points raised by aeroalias (&lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Cessna_172&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This airfoil guide also specifies the airfoils used for wing root and wing tip for a large range of aircraft and helicopters (&lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/aircraft.html&quot; rel=&quot;nofollow&quot;&gt;http://m-selig.ae.illinois.edu/ads/aircraft.html&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this airfoil guide, you can also check out any &quot;modern&quot; aircraft you are interested in and determine if the NACA airfoils or any other type of airfoils are used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. I just saw that aeroalias also referenced the airfoil guide. Do check it out, it's a fantastic resource.&lt;/p&gt;&#xA;" OwnerUserId="9425" LastEditorUserId="9425" LastEditDate="2015-09-10T06:09:07.267" LastActivityDate="2015-09-10T06:09:07.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20830" PostTypeId="1" CreationDate="2015-09-10T03:48:00.550" Score="-1" ViewCount="1638" Body="&lt;p&gt;Why is the below true when mobile devices such as mobile phones and designer watches with emergency beacons work without Line of sight?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most commercial aircraft transmit their GPS-based position twice per&#xA;  second. This is part of their ADS-B broadcasts. The problem with&#xA;  providing world-wide receiver coverage for this system is that the&#xA;  frequency it uses only travels line via line of sight, so it won't&#xA;  travel past the horizon.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Providing coverage over large bodies of water would require a network&#xA;  of buoys, which would be quite expensive.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Another possibility is to put ADS-B receivers on satellites. This&#xA;  concept is being developed by Thales Alenia Space and Iridium (Aireon)&#xA;  at the moment. The first satellites will launch next year, the system&#xA;  is expected to be operational in 2018.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From: &lt;a href=&quot;https://aviation.stackexchange.com/questions/2198/why-dont-all-commercial-aircraft-transmit-gps-data-in-real-time&quot;&gt;Why don&amp;#39;t all commercial aircraft transmit GPS data in real time?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11163" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2018-02-09T05:48:47.910" Title="Why do planes need line of sight for GPS to work?" Tags="&lt;gnss&gt;" AnswerCount="3" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20831" PostTypeId="2" ParentId="20830" CreationDate="2015-09-10T05:28:02.883" Score="10" Body="&lt;p&gt;&lt;strong&gt;tl;dr:&lt;/strong&gt; Mobile devices and designer watches with (RF) emergency beacons &lt;strong&gt;don't&lt;/strong&gt; work without line-of-sight to &lt;em&gt;some kind of receiver&lt;/em&gt;. Most types of RF communication signals require a close approximation of line-of-sight between the transmitter and receiver to work.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All GPS receivers require line-of-sight to fix their position. However, this line of sight is up (because the satellites are in orbit,) which is usually not obstructed unless you're inside a building, under water, under a bridge, under ground, etc. Any GPS receiver will stop working under those circumstances. Airplanes are very rarely in situations where their GPS receivers don't have a working signal, except when they're in a hangar. Since they're normally above ground and outside, they normally have no problem getting a GPS signal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the problem comes in is transmitting their location back to someone who's listening for it. This requires either radio communication to some ground-based system (or another aircraft,) such as the ADS-B receivers mentioned in the question. (Roughly) line of sight is required for this. The same is true of mobile devices. They also must be in range (which is often less than line-of-sight) of a receiver that is listening for their location transmission. In the case of cell phones, these receivers will just be cell towers. This is why, for example, we can't just track down the position of some crew or passenger's phone when looking for a boat or aircraft that has gone missing at sea (where there aren't any cell towers in range.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that radio-frequency signals (such as ADS-B or cellular communications) can penetrate some objects, but this ability is very limited, especially as you move to higher frequencies. Thick, dense objects (like concrete parking garages, overpasses, and tunnel roofs) will reduce (&lt;a href=&quot;https://en.wikipedia.org/wiki/Attenuation#Electromagnetic&quot;&gt;attenuate&lt;/a&gt;) the signal faster and conductive objects (such as water or metals like copper or aluminum) will nearly eliminate the signal with only rather thin layers. Also, in general, higher-frequency RF signals will be attenuated much more quickly than lower-frequency ones. This is why your home Wi-Fi or a cell phone works through perhaps a few walls, but the new 60 GHz wireless networks wouldn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of cell phones, the broadcast range is also intentionally limited so that more towers using the same channel can be packed into a smaller area to serve more people. If they didn't do this, there wouldn't be enough bandwidth to handle all of the cellular communication needs in densely-populated areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Earth's surface happens to be composed primary of rather dense soil and water, so radio signals don't travel through the Earth much at all. In general, any form of radio communication must either have no land or water between the transmitting and receiving antennas or else cause the signal to reflect off of higher layers of the atmosphere or curve around the Earth. Neither of those things works well in the frequency bands used by cell phones. It does work at some of the lower frequencies used by amateur radio operators and such, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Communications systems that need to work far away from land or otherwise in remote places where receivers can't reasonably be located within line-of-sight range on the surface will normally use satellites. This is because Earth is not between you and a satellite that is above you and, thus, isn't blocking your signal. Even connections to satellites don't normally work when the satellite is below the horizon (again, due to the Earth attenuating the signal,) but satellite communication systems are normally set up in &lt;a href=&quot;https://en.wikipedia.org/wiki/Satellite_constellation&quot;&gt;constellations&lt;/a&gt; that are designed to keep at least a certain number of satellites above the horizon in coverage areas at all times or else are set up in &lt;a href=&quot;https://en.wikipedia.org/wiki/Geostationary_orbit&quot;&gt;geostationary orbit&lt;/a&gt; where they will always remain directly above the same surface position.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-09-10T05:33:48.153" LastActivityDate="2015-09-10T05:33:48.153" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20832" PostTypeId="2" ParentId="20798" CreationDate="2015-09-10T07:10:10.973" Score="10" Body="&lt;p&gt;Just three data points: The tail surfaces of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-12&quot; rel=&quot;noreferrer&quot;&gt;Pilatus PC-12&lt;/a&gt; still use the venerable NACA 0012, even though a better alternative (from the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=fx71120-il&quot; rel=&quot;noreferrer&quot;&gt;Wortmann FX 71 L&lt;/a&gt; series) was proposed. It did not help that the Wortmann airfoil is used on many small airplanes, has more lift &lt;strong&gt;and&lt;/strong&gt; less drag and an abundance of data exists on it: The (mainly British) engineers at Pilatus were too conservative to use anything newer than an airfoil from the 1920s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YqOHl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YqOHl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilatus PC-12 (picture &lt;a href=&quot;http://www.aircraftcompare.com/aircraft_images/1532.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Seastar&quot; rel=&quot;noreferrer&quot;&gt;Dornier Seastar&lt;/a&gt;, designed by a group of old Dornier engineers in the early 1980s, used the same airfoils as the venerable &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_17&quot; rel=&quot;noreferrer&quot;&gt;Do-17&lt;/a&gt; of the 1930s, namely the NACA 23012. Later flight tests showed the need to add a leading edge droop on the outer wing, a modification that cost several knots in top speed and would have been entirely avoidable with better airfoils and/or the use of washout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F7O9l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F7O9l.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dornier Seastar. Picture by &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?title=User:Rschider&amp;amp;action=edit&amp;amp;redlink=1&quot; rel=&quot;noreferrer&quot;&gt;Rschider&lt;/a&gt; (own work).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The excellent Polish aerobatic glider &lt;a href=&quot;https://en.wikipedia.org/wiki/Swift_S-1&quot; rel=&quot;noreferrer&quot;&gt;Swift S-1&lt;/a&gt; uses indeed a NACA 6-digit airfoil, the $64_1412$. As Jerzy Makula explained to me, it gives excellent snap roll and spin control, and when flying the prototype, I could control the exit direction from a spin within ±15° with very little practice. Jerzy simply took &lt;a href=&quot;https://en.wikipedia.org/wiki/SZD-21_Kobuz&quot; rel=&quot;noreferrer&quot;&gt;what had worked before&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vrkfq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vrkfq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swift S-1. Picture by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:TSRL&quot; rel=&quot;noreferrer&quot;&gt;TSRL&lt;/a&gt; (own work).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, small companies or experimental airplane builders still rely sometimes on the NACA series, but in general better alternatives exist. Big companies use custom-made airfoils, helped by computer codes which model not only the two-dimensional flow around the isolated airfoil, but can optimize the specific wing section by including the influence of engine nacelles, pylons and the fuselage. Well-designed wing roots do not use one single airfoil, but a three-dimensional shape which minimizes interference drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is true even for glider companies. While &lt;a href=&quot;https://en.wikipedia.org/wiki/Wolf_Lemke&quot; rel=&quot;noreferrer&quot;&gt;Wolf Lemke&lt;/a&gt; used his own creations for the early LS series of gliders on the basis of their good looks (and with good success), todays gliders are designed in the computer, helped by &lt;a href=&quot;http://www.lr.tudelft.nl/nl/&quot; rel=&quot;noreferrer&quot;&gt;university departments&lt;/a&gt; which relish the chance to let students work on real-world designs.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-10T07:39:37.370" LastActivityDate="2015-09-10T07:39:37.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20833" PostTypeId="2" ParentId="20816" CreationDate="2015-09-10T08:14:20.267" Score="15" Body="&lt;p&gt;Why not?&lt;/p&gt;&#xA;&lt;p&gt;There have been &lt;a href=&quot;http://articles.chicagotribune.com/1992-12-20/travel/9204250793_1_passenger-plane-freighters-test-pilots&quot; rel=&quot;nofollow noreferrer&quot;&gt;several cases&lt;/a&gt; of near-sonic and even &lt;a href=&quot;http://everything2.com/user/archiewood/writeups/airliners+that+have+gone+supersonic+and+survived&quot; rel=&quot;nofollow noreferrer&quot;&gt;supersonic&lt;/a&gt; dashes by the Boeing 747, and the damage to the &lt;a href=&quot;https://en.wikipedia.org/wiki/China_Airlines_Flight_006&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines Flight 006&lt;/a&gt; elevator was done by landing gear doors which ripped off when the main gear was extended and its doors hit the elevator.&lt;/p&gt;&#xA;&lt;p&gt;There have been a few unintentional supersonic dives, and in those cases the actions taken by the crew to decelerate caused damage to the aircraft. &lt;a href=&quot;https://en.wikipedia.org/wiki/TWA_Flight_841_(1979)&quot; rel=&quot;nofollow noreferrer&quot;&gt;TWA Flight 841&lt;/a&gt;, a Boeing 727 which rolled into a dive, and China Airlines Flight 006 overstressed the airframe, but both aircraft returned to service after repairs.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.chicagotribune.com/news/ct-xpm-1992-12-20-9204250793-story.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;IAI experience&lt;/a&gt; tells me it needs a dive with a nose-down angle of 18° to get a Boeing 747 to Mach 0.98. Since almost all surfaces experience already supersonic flow at this speed, going the step to Mach 1.01 would need not much more, maybe 25°. Pulling up from such a dive by means of the stabilizer should entirely be possible without exceeding g limits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-04-05T16:09:16.730" LastActivityDate="2021-04-05T16:09:16.730" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="20836" PostTypeId="2" ParentId="20825" CreationDate="2015-09-10T14:03:02.517" Score="2" Body="&lt;p&gt;All the airports listed in the AIC are quite tricky to takeoff/land in. For example, the Lengpui airport runway is a classic example of &lt;a href=&quot;https://en.wikipedia.org/wiki/Tabletop_runway&quot; rel=&quot;nofollow noreferrer&quot;&gt;tabletop runway&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DRoN1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DRoN1.jpg&quot; alt=&quot;Lengpui runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.misual.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Leh runway is surrounded by steep hills.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/32q0x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/32q0x.jpg&quot; alt=&quot;Leh runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: geolocation.ws&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The kullu airport runway has a river in both its ends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SsGNr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SsGNr.jpg&quot; alt=&quot;Kullu runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.airportsindia.org.in&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason for these restrictions. I'm not aware of any such &lt;em&gt;regulatory&lt;/em&gt; restrictions in case of other countries. However, the operating airlines &lt;a href=&quot;http://www.pprune.org/tech-log/398057-first-officer-limitations.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;can have their own rules&lt;/a&gt; about (&lt;a href=&quot;http://airfieldcharts.com/airportcategorisation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Category C&lt;/a&gt;) airports.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-10T14:03:02.517" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20837" PostTypeId="1" AcceptedAnswerId="20843" CreationDate="2015-09-10T15:21:36.563" Score="16" ViewCount="1950" Body="&lt;p&gt;I know that restrictions do not always apply and ATC can cancel them or pilots can request for speed restriction being canceled. But &lt;em&gt;why&lt;/em&gt; is there such a speed restriction in first place? Are there any reasons other than noise abatement?&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="9716" LastEditDate="2015-09-11T05:21:35.007" LastActivityDate="2015-09-11T05:21:35.007" Title="Why are speed restrictions imposed for flights flying below 10,000 ft?" Tags="&lt;air-traffic-control&gt;&lt;airspeed&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20838" PostTypeId="1" AcceptedAnswerId="20842" CreationDate="2015-09-10T15:29:08.747" Score="20" ViewCount="15661" Body="&lt;p&gt;The situation is as following - I requested flight following at approach, got a squawk and instructed to maintain VFR with heading and altitude at my discretion. My route is through class D and class C airspace for the altitude I chose. The question is - should I establish additional communications or report to the approach controller about flying through the class C and D airspace, or I am already permitted to do this?&lt;/p&gt;&#xA;" OwnerUserId="1054" LastEditorUserId="1696" LastEditDate="2015-09-10T22:26:16.173" LastActivityDate="2021-04-12T23:39:36.677" Title="Does Flight Following automatically include permission to fly through class C or D airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;class-c-airspace&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20839" PostTypeId="2" ParentId="20815" CreationDate="2015-09-10T15:40:03.547" Score="8" Body="&lt;p&gt;KDEN has a lot of runways, so they have the option of not always using some of them. &lt;a href=&quot;https://aviation.stackexchange.com/questions/20815/why-is-denver-international-airport-runway-16r-34l-rarely-used#comment46806_20815&quot;&gt;As FreeMan pointed out&lt;/a&gt;, 12,000 feet is plenty for just about any aircraft flying in or out, even at 5,300 feet elevation. Being such a long runway, it may also be good to leave it open so that no aircraft need to be moved in case an aircraft declaring emergency would need the extra length. Runway use will depend on the wind and traffic, so depending on when you are observing, you may not often see conditions where it is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;North flow: arrivals on 34L could interfere with runway 7/25, and for departures it is further from the terminal than 34R. &lt;a href=&quot;https://aviation.stackexchange.com/a/20823/1696&quot;&gt;TomMcW also points out&lt;/a&gt; potential noise abatement concerns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;South flow: departures on 16R could interfere with runway 7/25, and for arrivals it is further from the terminal than 16L.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with 17L/35R currently closed it is not always necessary to use 16R/34L. 8/26 and 7/25 can be used for east/west departures and arrivals, and 17R/35L can be used as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runway 16R/34L can still be used as a secondary runway though. It can certainly be used as 16R for parallel approaches with 16L, or departures as 34L with approaches on 34R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put things in perspective, Denver has more runways than both KLAX and KATL, which see more aircraft movements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, while far from authoritative, the &lt;a href=&quot;http://www.denartcc.org/docs/tiki-index.php?page=SOP%3A%20KDEN&amp;amp;structure=Standard%20Operating%20Procedures&quot; rel=&quot;nofollow noreferrer&quot;&gt;virtual Denver ARTCC&lt;/a&gt; lists 16R/34L as a secondary runway in all situations.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-09-10T15:40:03.547" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20841" PostTypeId="2" ParentId="20838" CreationDate="2015-09-10T16:15:24.617" Score="1" Body="&lt;p&gt;Since you are already in radio contact with the ATC agency that controls the Charlie airspace (aka Approach), you are already allowed to enter it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If Approach doesn't want you in their Charlie, they'll say so: &quot;N12345, remain outside the Charlie&quot;.)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-09-10T16:15:24.617" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20842" PostTypeId="2" ParentId="20838" CreationDate="2015-09-10T16:18:56.293" Score="18" Body="&lt;p&gt;Lets back up a minute and discuss what is required to enter C and D airspace.&lt;/p&gt;&#xA;&lt;p&gt;For C and D airspace you must establish 2 way radio communications with tower or approach controller. Let's first discuss how this works if you are not taking Flight Following. As you approach Class C airspace you hail them and wait for a response, for example,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;You: &amp;quot;Allentown Approach Piper 1234J @ 3000 en route to Queen City Municipal&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Controller: &amp;quot;1234J Squawk 1-3-5-2 and Ident&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Since the controller responded with your tail number you may enter the Charlie airspace (Delta has the same requirements).&lt;/p&gt;&#xA;&lt;p&gt;Now when you are under Flight Following, ATC will coordinate a handoff to the Approach or Tower for the airspace you are about to enter, or ATC will say &amp;quot;radar services terminated,&amp;quot; and you must contact the controller/tower yourself before entering.&lt;/p&gt;&#xA;&lt;p&gt;You &lt;strong&gt;SHOULD NOT&lt;/strong&gt; change frequencies until you are told to do so, since ATC may be trying to give you a traffic advisory. You can however tune your second radio (if you have one) to the approach/tower you are approaching, and begin to monitor traffic.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-25T15:24:14.490" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20843" PostTypeId="2" ParentId="20837" CreationDate="2015-09-10T16:29:40.723" Score="13" Body="&lt;p&gt;The speed limits were set by FAA in the early days of jet age for better control of the aircraft and safety where the air traffic (in VFR) is the densest and have little to do with noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR § 91.117 states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;TWA Flight 553, a DC 9 &lt;a href=&quot;https://en.wikipedia.org/wiki/TWA_Flight_553&quot;&gt;collided with&lt;/a&gt; a Beechcraft Baron, killing 26 people on March 9, 1967. NTSB investigation determined that due to the high rate of descent of the DC-9, its pilots were not able to see the other plane in time to avoid a collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following this accident the FAA issued Advisory Circular 90-32 titled 'Air traffic control and general operations, radar capabilities and limitations' in Aug 1967.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.airdisaster.com/reports/ntsb/AAR68-AI.pdf&quot;&gt;NTSB report&lt;/a&gt; on the accident, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA has adopted a rule establishing that all aircraft flying below 10,000ft m.s.l will be limited to a maximum speed of 250kts effective December 15, 1967... (to) provide a more realistic 'see and avoid' environment in the airspace below 10,000 feet mean sea level (MSL) where the traffic congestion is greatest .... &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-10T16:53:44.910" LastActivityDate="2015-09-10T16:53:44.910" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20844" PostTypeId="2" ParentId="20830" CreationDate="2015-09-10T16:31:00.257" Score="4" Body="&lt;p&gt;You are asking about two very different, unrelated technologies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS is the technology that determines the receiver's position based on signals from satellites.  Those satellites are overhead, so line-of-sight is pretty easy. &lt;br&gt;&lt;em&gt;(airplanes usually don't fly in caves, buildings or other places where the overhead view is blocked)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B is the technology that broadcasts the position determined by GPS to other airplanes and ground receivers at regular intervals.  It also requires line-of-site between the sender and receiver. (more-or-less: slightly indirect routes will work if the signal is not degraded too much)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also claim that cell phones and other devices don't require line-of-sight.  That is only true to the extent that the direct line-of-sight isn't terribly obstructed, which is usually related to how nearby and how powerful the transmitter is.  You don't always get cell phone signals in the interior of large concrete and metal buildings, or deep in parking garages.  It is also why cell-towers are mounted up high and in locations where they can see a lot of terrain.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2015-09-10T16:31:00.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20847" PostTypeId="1" CreationDate="2015-09-10T23:54:02.477" Score="7" ViewCount="13410" Body="&lt;p&gt;From time to time I land at &lt;a href=&quot;https://en.wikipedia.org/wiki/Wellington_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Wellington Airport&lt;/a&gt; in an A-320. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway has sea at either end and is 2,081m (6,827ft) long.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's never been a problem but I find landing there a bit nerve wracking (the frequent high winds in the area means just getting the plane over the fence is sometimes a little more exciting that most would prefer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine that getting the wheels onto the runway as soon as possible is a priority so you can start braking but I wonder in a flat out emergency how much runway does an A-320 need (full of passengers/cargo but not much fuel) to stop if nothing else matters but stopping ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: I meant to say I do appreciate that wet/dry runway and head wind strength would influence this quite strongly but I'm just looking a ballpark figure.&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="62" LastEditDate="2015-09-11T00:25:33.303" LastActivityDate="2020-05-24T16:49:39.427" Title="In an emergency, how much runway does an A320 need to stop safely?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;airbus-a320&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="20849" PostTypeId="2" ParentId="20847" CreationDate="2015-09-11T01:49:29.910" Score="10" Body="&lt;p&gt;Airbus's charts for the A320 suggest that it requires approximately 4,500ft for a sea-level landing at typical landing weight. I've extracted this from &lt;a href=&quot;http://www.aircraft24.com/images/aircraftpics/76/attach_115976_1.pdf&quot;&gt;this Airbus document&lt;/a&gt; (the A320 landing chart is on page 49), which is admittedly more of a promotional brochure than an operating manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wellington's runway is 5,955 ft between thresholds, and 6,827ft overall, so there is some room for error. However, depending on the nature of the 'flat-out emergency' a pilot may approach faster implying a longer landing roll, or choose a firm landing and significant abuse of the brakes to shorten it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Christchurch and Auckland airports both offer much longer runways at 10,787ft and 11,925ft respectively, so I'd speculate that a pilot faced with a known problem with brakes or thrust reversers might elect to divert there if range permitted.&lt;/p&gt;&#xA;" OwnerUserId="11179" LastEditorUserId="11179" LastEditDate="2015-09-11T01:57:47.080" LastActivityDate="2015-09-11T01:57:47.080" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20850" PostTypeId="1" AcceptedAnswerId="20851" CreationDate="2015-09-11T05:17:08.260" Score="-1" ViewCount="387" Body="&lt;p&gt;I know generally it is about 170mph. But what is the actual speed in mph that an airliner has to reach before it takeoff's.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-11T06:26:26.740" Title="What is the typical speed an airliner has to reach before lifting in the air" Tags="&lt;airliner&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-09-11T14:43:46.337" ContentLicense="CC BY-SA 3.0" />
  <row Id="20851" PostTypeId="2" ParentId="20850" CreationDate="2015-09-11T05:54:23.647" Score="8" Body="&lt;p&gt;It depends on what type of an airliner you are talking about. Even then, take off or rotation speed in every flight is different. Pilots need to consider many variables like air density, aircraft gross weight, lift coefficient (aerodynamics of the plane), and aircraft configuration (flap or slat position, as applicable), according to &lt;a href=&quot;https://en.wikipedia.org/wiki/Takeoff#Speed_required&quot;&gt;Wikipedia&lt;/a&gt;. This is a few examples from the &lt;a href=&quot;http://www.aerospaceweb.org/question/performance/q0088.shtml&quot;&gt;Aerospaceweb.org&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 737 at 100,000 lb, rotation speed is 150 mph / 130 KIAS.&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320 at 155,000 lb, rotation speed is 170 mph / 150 KIAS.&lt;/li&gt;&#xA;&lt;li&gt;Boeing 747 at 800,000 lb, rotation speed is 180 mph / 155 KIAS.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Each plane has a set of calculations which pilots use to determine a specific speed (V&lt;sub&gt;1&lt;/sub&gt;, V&lt;sub&gt;R&lt;/sub&gt; - rotation, and V&lt;sub&gt;2&lt;/sub&gt;) for each flight. Modern airliners come equipped with their own software and/or computer designed for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="9126" LastEditorUserId="572" LastEditDate="2015-09-11T06:26:26.740" LastActivityDate="2015-09-11T06:26:26.740" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20852" PostTypeId="1" AcceptedAnswerId="20853" CreationDate="2015-09-11T06:26:43.003" Score="0" ViewCount="197" Body="&lt;p&gt;I don't know what they are called. In case of emergency like smoke they deploy, but where do this oxygen come from.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-11T08:11:12.673" Title="Where does the oxygen come from in the deployable breathing masks?" Tags="&lt;emergency&gt;&lt;oxygen&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-09-11T08:22:32.000" ContentLicense="CC BY-SA 3.0" />
  <row Id="20853" PostTypeId="2" ParentId="20852" CreationDate="2015-09-11T06:30:07.433" Score="2" Body="&lt;p&gt;The oxygen is provided through &lt;a href=&quot;http://www.skybrary.aero/index.php/Chemical_Oxygen_Generators&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chemical Oxygen Generators&lt;/a&gt;. Oxygen masks are triggered either automatically given certain conditions or by the flight crew.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Oxygen generators are usually installed in above each seat row. If the cabin altitude reaches a predetermined height (14,000' is standard) or if the system is activated by the flight crew, overhead panels open and oxygen masks drop out. To put the mask on, it is necessary for the intending user to pull it down and this action releases the firing pin and activates the generator.&lt;/p&gt;&#xA;&lt;p&gt;The oxidizer core of an oxygen generator usually consists mainly of Sodium Chlorate (NaClO&lt;sub&gt;3&lt;/sub&gt;) mixed with &amp;lt;5% Barium Peroxide (BaO&lt;sub&gt;2&lt;/sub&gt;) and &amp;lt;1% Potassium Perchlorate (KClO&lt;sub&gt;4&lt;/sub&gt;). This core is activated by the application of heat generated usually generated by a mixture of lead styphnate and tetracene which itself is activated by a small explosive charge in a percussion cap are a mixture. This explosive charge is set off by the release of a spring-loaded initiation mechanism which is restrained until released by a pull on the lanyard which is visible when oxygen masks are released from overhead panels. Once activated, the chemical reaction and production of oxygen will continue until the generator has been exhausted which is typically in the range 12 to 20 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-11T08:11:12.673" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20856" PostTypeId="1" AcceptedAnswerId="20857" CreationDate="2015-09-11T08:05:41.217" Score="22" ViewCount="27549" Body="&lt;p&gt;I was wondering if there are regulations for when a flight requires both a pilot and copilot.&lt;br&gt;&#xA;I always assumed a copilot is required once civilian passengers are aboard, but when I recently was a passenger in South-African and South-American sight seeing flights, the pilot was always flying alone. Flights in europe however always had a pilot and copilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this regulated by laws or can the pilot / airline company decide it on their own?&lt;/p&gt;&#xA;" OwnerUserId="11183" LastActivityDate="2019-04-10T16:25:09.647" Title="When does a flight require a copilot?" Tags="&lt;pilots&gt;&lt;regulations&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20857" PostTypeId="2" ParentId="20856" CreationDate="2015-09-11T08:31:14.517" Score="24" Body="&lt;p&gt;A flight requires pilot &amp;amp; copilot when the aircraft being flown requires it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A multi-crew aeroplane is one that requires a flight crew of at least two pilots. One of them is the pilot-in-command (the captain) and the other is the co-pilot (or first officer). All jet air transport aeroplanes and the vast majority of turbine powered air transport aircraft and business jet are multi-crew aeroplanes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The definition in &lt;a href=&quot;http://www.icao.int/safety/airnavigation/nationalitymarks/annexes_booklet_en.pdf&quot;&gt;Annex 1 — Personnel Licensing&lt;/a&gt; states that it is: &quot;an aircraft required to be operated with a co-pilot as specified in the flight manual or by the air operator certificate.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the secondary answer is no, it cannot be decided by a pilot or an operator, it is a statutory requirement.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="524" LastEditDate="2015-09-11T11:46:34.060" LastActivityDate="2015-09-11T11:46:34.060" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="20858" PostTypeId="1" AcceptedAnswerId="20860" CreationDate="2015-09-11T08:52:23.810" Score="6" ViewCount="216" Body="&lt;p&gt;When air-crash investigation completes, either NTSB/FAR/other investigating agency finds some issue with instruments/equipments. What is the minimum timeline given to instrument/equipment manufacturer to fix the issue? (May be based on the severity of the issue).&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="19" LastEditDate="2016-12-05T11:33:04.313" LastActivityDate="2016-12-05T11:33:04.313" Title="What's the minimum timeline for fixing the issues/finding from NTSB/FAR?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;aircraft-subsystem&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20859" PostTypeId="2" ParentId="20858" CreationDate="2015-09-11T09:48:06.557" Score="1" Body="&lt;p&gt;It would depends on various factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First is the severity of the issue. If it can cause a accident then the entire fleet of affected aircraft will be &lt;em&gt;grounded&lt;/em&gt; until the fix has been certified and installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the issue is not that severe then it will depend on how hard the fix is to install. The harder/more time consuming it is the more time is given. Some fixes can be put in during the normal pre-flight check. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then they will give enough time for the fleet to get cycled through the scheduled &lt;a href=&quot;https://aviation.stackexchange.com/a/13085/609&quot;&gt;more extensive A or B checks&lt;/a&gt; where the fix will get installed.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-09-11T09:48:06.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20860" PostTypeId="2" ParentId="20858" CreationDate="2015-09-11T12:07:34.910" Score="6" Body="&lt;p&gt;That is up to the &lt;em&gt;civil aviation authority&lt;/em&gt;, which in most countries is distinct agency from the investigation board (in USA this is FAA), to decide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They will take into consideration how likely the problem is to repeat, how big risk it would be if it does¹ and as secondary criteria how much work the fix is and how much it will cost. What must be done will be published in an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airworthiness_Directive&quot; rel=&quot;nofollow&quot;&gt;airworthiness directive&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the problem is serious, they will prohibit any further flights except for testing purposes until fix is installed. And remember the fix may not be known yet. For example after the 787 battery fires, FAA published airworthiness directive that prohibited operations until “approved fix is installed” couple of days after the third incident when they just started to discuss what the fix should be with Boeing and whole fleet remained grounded for almost half a year until the modified batteries were ready.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other end of the scale a problem may not necessarily result in mandatory change at all. Many issues simply result in mandating additional inspections, shortening intervals between inspections or shortening maximum service life of some component, which may be relaxed again &lt;em&gt;if&lt;/em&gt; the manufacturer develops an improved version of the component &lt;em&gt;and&lt;/em&gt; the operator installs it, neither of which is mandatory. Even quite severe problems may just be solved with inspections, because most components have inherently limited life and the problem just indicated higher wear then originally anticipated.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ It is important to remember that the investigators don't only investigate crashes, but they get reports of all &lt;em&gt;incidents&lt;/em&gt;, which means any failure where there was elevated risk. They then investigate those where they consider the risk significant or that are more common then expected. So often things are investigated where the probability of fatal outcome is low. In such cases the investigators will only consider safety and will publish a safety recommendation, but the aviation authority has to also consider other practical aspects and may choose not to enforce it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-09-11T13:47:50.027" LastActivityDate="2015-09-11T13:47:50.027" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20862" PostTypeId="1" AcceptedAnswerId="20863" CreationDate="2015-09-11T16:13:26.617" Score="16" ViewCount="2191" Body="&lt;p&gt;There is a related question about when regulations require a co-pilot. This question is about which airplanes cannot be &lt;strong&gt;physically&lt;/strong&gt; flown without at least two people operating it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any airplanes currently in existence with such a requirement?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be because there are controls or systems that must (as in fall-from-the-sky-must, not FAA-must) be controlled or monitored by people in different stations. And by &quot;flight,&quot; I mean taking off, controlled flight, and landing (in one piece) - and not any mission specific, tactical or navigational requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/20856/when-does-a-flight-require-a-copilot&quot;&gt;When does a flight require a copilot?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-09-12T17:34:17.427" Title="Which airplanes require two (or more) pilot/operators?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20863" PostTypeId="2" ParentId="20862" CreationDate="2015-09-11T16:18:16.690" Score="21" Body="&lt;p&gt;The question boils down to, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Are there any critical flight controls that are out of reach of the&#xA;  Pilot In Command?&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some older aircraft that required a &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_engineer&quot; rel=&quot;noreferrer&quot;&gt;Flight Engineer&lt;/a&gt; in the third seat (not the copilot) and controls at that station that were not available to the pilot or copilot. Some older variants of the 747 (pre 400 series, not sure if any are still in service in their original config) had a required 3 man crew. The Concorde (when it flew) had its fuel system controls at the FE station and those had to manned in flight as the fuel had to be moved around during different stages. You may be more likely to find these older airframes/configurations in cargo service these days. For these planes the legal requirement is often 3 people (not 2) but from a pure &quot;get it off the ground, fly it, land it&quot; case you need at least 2 people to operate it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FE station looks something like this in most planes (747 in this pic) &#xA;&lt;a href=&quot;https://i.stack.imgur.com/75tnB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/75tnB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.hoppie.nl/pic/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde had a pretty daunting panel as well &#xA;&lt;a href=&quot;https://i.stack.imgur.com/welMt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/welMt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that being said you would need at least a Pilot and FE to physically fly the plane since the pilot cant reach all the controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern avionics controls (glass cockpits mainly) have allowed more information to be presented directly to the pilot in a more condensed manner and allows displays to have multiple functions unlike gauges which tend to display only a single datum.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-09-11T16:55:33.123" LastActivityDate="2015-09-11T16:55:33.123" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20865" PostTypeId="1" AcceptedAnswerId="20867" CreationDate="2015-09-11T17:02:34.837" Score="8" ViewCount="342" Body="&lt;p&gt;Looking over the comments and answers in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3915/in-what-cases-does-it-make-sense-to-buy-a-plane-before-you-begin-pilot-training&quot;&gt;this question&lt;/a&gt; got me to thinking: How does a new pilot get familiar with the large variety of GA aircraft when contemplating a purchase?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initially there's a vast number of aircraft to even be aware of—for example, I'd never heard of a &lt;a href=&quot;https://en.wikipedia.org/wiki/American_Champion_Citabria&quot; rel=&quot;nofollow noreferrer&quot;&gt;Citabria&lt;/a&gt; before today. So I suspect it would be easy to overlook the perfect aircraft by virtue of simply never having a chance encounter with it. I suppose the answer to this is to attend airshows and fly-ins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then obviously some considerations can be satisfied with light research, such as seating and performance characteristics. But outside of that, once you have a short list, how does a pilot go about getting a &quot;test drive&quot;..?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like so many before, I'm presently learning in a 172. Afterwards, though, I'd be interested in getting endorsed for a low-wing. A nearby FBO offers training in Piper Arrows—but what if I was curious about flying a Mooney, or a V-tailed Bonanza ..or a ..Citabria?? :) How do the Mooney pilots get their first flight in one??&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly interested in light, single-engine models, and I realize this question is rather conversational, but I'll appreciate any insights.&lt;/p&gt;&#xA;" OwnerUserId="9850" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2017-03-03T08:12:52.327" Title="What are the strategies for getting familiar with a GA aircraft before considering a purchase?" Tags="&lt;aircraft-purchase&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20866" PostTypeId="1" AcceptedAnswerId="20868" CreationDate="2015-09-11T17:06:49.943" Score="14" ViewCount="3875" Body="&lt;p&gt;Let's say the weather is a little above VFR minimums (let's say it is 1700ft and 3SM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approach controller vectors me on to the final, and then clears me for a visual approach. For some reason (such as bad crosswinds), I feel like aborting my approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point, am I allowed to &quot;go around&quot; or do I have to execute a missed approach procedure (if so, which one?) unless advised otherwise by tower?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what if it was an uncontrolled airport whereby I'd have to make this decision myself before contacting approach again?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastActivityDate="2017-06-12T18:22:06.797" Title="On a &quot;Visual Approach&quot;, do I execute a &quot;missed approach&quot; or do I go around?" Tags="&lt;approach&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20867" PostTypeId="2" ParentId="20865" CreationDate="2015-09-11T17:27:18.217" Score="6" Body="&lt;p&gt;There are lots of ways to go about this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Rent:&lt;/strong&gt; as you have mentioned nearby FBO's have various planes although they are almost always Pipers (Warriors, Arrows, occasionally a Saratoga or Lance) or Cessnas since those are common trainers. You may also find a light twin here and there as well as a Grumman or something like that. In this case you can rent what you want to try and go up with an instructor. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Friends:&lt;/strong&gt; As you fly more you will meet people at the airport. Often times these are plane owners and they have a whole variety of stuff. Eventually people may offer to take you out for a flight in their plane (which will be way better maintained than a lot of trainers). If you tell someone you are interested in purchasing the same make and model they have, they may be more inclined to take you up. You may also meet other people who are training in a different plane than you. For example, I fly the Warrior and Archer at my school and another student who I have become friendly with flies the 172. Since we are not check out in the other planes respectively and we are about at the same point (close to our check rides) Im sure we will fly with each other in the respective planes in the future. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Clubs:&lt;/strong&gt; A lot of local airports have flight clubs that sometimes own a nice variety of stuff and you may be able to meet a member and have them take you up to show you around what ever it is they have, you may even be able to join the club and get checked out in their planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Internet:&lt;/strong&gt; The internet is abuzz with forums for just about every big maker out there. Some are free and others are super cheap to join if they cost anything at all. You can often times find local owners on these forums who may be willing to take you up or at least show you their plane. You would be surprised how hard it can be to find people to fly with sometimes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dealers:&lt;/strong&gt; Much like cars new planes come from dealers. You can always try your local dealer (although Im not sure if they will take you up) I would think they would at least let you sit in the plane. There are dealers spread across the country but if you can rent a plane now you can always fly to them (&lt;a href=&quot;http://www.piper.com/locate-dealer/&quot; rel=&quot;noreferrer&quot;&gt;Piper&lt;/a&gt;, &lt;a href=&quot;http://www.vanbortel.com/&quot; rel=&quot;noreferrer&quot;&gt;Cessna&lt;/a&gt;, &lt;a href=&quot;http://www.lasar.com/&quot; rel=&quot;noreferrer&quot;&gt;Mooney&lt;/a&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;When You Buy:&lt;/em&gt; When (if) you buy a plane you will need to insure it. Generally insurance companies will require time in type to get the insurance. You can sometimes agree upon mandatory instructor time in the plane you just bought before you fly it solo. This allows you to be able to buy just about any plane and not have a ton (if any) time in it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Finding Strange Planes:&lt;/em&gt; When (if) you go to buy a plane you will define your mission. After doing so you will begin to talk to people about what you want and you will get plenty of suggestions on what to buy that fits your mission. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Strange Planes Are Strange For A Reason:&lt;/em&gt; I can only assume you are training (or have your PPL) and are thinking about getting a plane. To this I will offer some advice I have been given. Planes are no small item to own, fiscally, legally, and simply physically, they require a lot of space. There is a reason the common models are common. They fit a lot of missions, are generally reliable, easy to fix and get parts for as well as easy to fly. While I lust for a Mooney M20 Acclaim Type S the truth is (money aside) I am no where near ready for a 200+ knot plane that is nothing but slippery. Remember to respect the machine.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-09-11T19:15:50.220" LastActivityDate="2015-09-11T19:15:50.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20868" PostTypeId="2" ParentId="20866" CreationDate="2015-09-11T19:52:26.930" Score="17" Body="&lt;p&gt;First, a caution: IFR procedures can (and do) vary between countries. It is incumbent on the pilot to study the respective authority's Aeronautical Information Publication (AIP) to understand local procedures before flight. When asking questions about instrument flight procedures, it is helpful to know which countries you are specifically traveling through. While the vast majority of countries simply adopt ICAO procedures, many have significant deviations (the United States included).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.navcanada.ca/EN/media/Publications/ICAO-Doc-4444-EN.pdf&quot;&gt;ICAO Doc 4444 (PANS/ATM)&lt;/a&gt;, section 6.5.3 discusses instrument flight that terminates into a visual approach. Interestingly, the document is silent on what happens if the approach is aborted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the United States, the FAA is more explicit. In the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;Aeronautical Information Manual&lt;/a&gt;, section 5-4-23 visual approaches are specifically addressed. Paragraph (e) details what should happen if a visual approach is terminated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A visual approach is not an IAP and therefore &lt;strong&gt;has no missed approach segment&lt;/strong&gt;. If a go around is necessary for any reason, aircraft operating at controlled airports will be issued an appropriate advisory/clearance/instruction by the tower. At uncontrolled airports, aircraft are expected to remain clear of clouds and complete a landing as soon as possible. If a landing cannot be accomplished, the aircraft is expected to remain clear of clouds and contact ATC as soon as possible for further clearance. Separation from other IFR aircraft will be maintained under these circumstances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-09-11T19:52:26.930" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20869" PostTypeId="1" AcceptedAnswerId="20873" CreationDate="2015-09-11T21:42:51.963" Score="4" ViewCount="5070" Body="&lt;p&gt;This is a picture of the supposed SR-72 Aurora. What kind of advantages would this have over the SR-71, in terms of its triangle design? Paper airplanes have the same shape, and fly really well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SFwcg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SFwcg.jpg&quot; alt=&quot;Views of &amp;quot;Aurora&amp;quot; aircraft with A340 for scale&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZNIJj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZNIJj.jpg&quot; alt=&quot;SR-71 top planform view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SR-71 design that I am comparing it to.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="755" LastEditDate="2015-09-15T17:51:17.177" LastActivityDate="2016-10-25T15:06:28.613" Title="What advantages would a triangular shaped spy plane have over a an SR-71?" Tags="&lt;aerodynamics&gt;&lt;sr-71&gt;&lt;sr-72&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20870" PostTypeId="1" CreationDate="2015-09-11T21:44:24.077" Score="10" ViewCount="1248" Body="&lt;p&gt;I am browsing the planespotters.net database, and I see plenty of planes in their twenties. Delta, for example, has 117 MD-88 with an average age of 25 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While other planes are scrapped with no apparent reason when they are not even 10 years old: when Malev went bust, all its B736s were scrapped, 6 planes that were around 8 years old. &lt;a href=&quot;https://www.planespotters.net/production-list/search?fleet=Malev-Hungarian-Airlines&amp;amp;manufacturer=Boeing&amp;amp;subtype=737-600&amp;amp;fleetStatus=historic&quot;&gt;https://www.planespotters.net/production-list/search?fleet=Malev-Hungarian-Airlines&amp;amp;manufacturer=Boeing&amp;amp;subtype=737-600&amp;amp;fleetStatus=historic&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not the only example, there are plenty of aircrafts not older than 15 years that are scrapped, while other planes are still flying in the late twenties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the reasons?  &lt;/p&gt;&#xA;" OwnerUserId="9939" LastEditorUserId="1467" LastEditDate="2015-09-11T21:54:47.720" LastActivityDate="2015-09-11T23:32:43.667" Title="Why some planes are scrapped way sooner than others?" Tags="&lt;commercial-aviation&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20871" PostTypeId="2" ParentId="20870" CreationDate="2015-09-11T23:01:54.373" Score="7" Body="&lt;p&gt;What it boils down to is, does the value of all its parts greater than the value of keeping the aircraft whole and trying to sell or lease it. With your mentioned B736s and I'll add Frontier Airlines A318s which also went to be parted out and scrapped, their parts were far more valuable on the parts market than the owners could get in terms of sales prices or leasing prices. Those types in particular are less economical than many other types, and there is a great demand for spare parts, such that when the airlines went belly up, or decided they no longer wanted the type, the lessors couldn't find anyone who was willing to pay enough to make it worth it, and they decided to scrap them and make their money back from the value of the parts.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-09-11T23:01:54.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20872" PostTypeId="2" ParentId="20870" CreationDate="2015-09-11T23:32:43.667" Score="10" Body="&lt;p&gt;In general, the retirement age of aircraft is around 25 years and most of the aircraft fleet in operation is well over 15 years old.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vllwy.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vllwy.png&quot; alt=&quot;Aircraft retirement&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airfinancejournal.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various reasons for scrapping the aircrafts rather than selling them to other airlines (or other buyers, in general). &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Availability of Buyers- People should be ready to buy the aircraft on offer. In this case, the aircrafts were probably offered for sale at a time when tn the economy was in a bad shape and the airlines would've found it difficult to sell them.&lt;/li&gt;&#xA;&lt;li&gt;Condition of the aircraft- Though the aircraft may be new, it has to be seen if it is properly maintained. In case the aircraft are not maintained properly or had the parts been cannibalized for spares, it would be difficult to find buyers as it takes a lot of money to put the aircraft back into operation.&lt;/li&gt;&#xA;&lt;li&gt;Sum of Parts- In some cases, the sum of parts of the aircraft may be more valuable than the aircraft itself. Cost of operating an aircraft is quite high and the aircraft parts like engines etc are quite valuable. It would've made more economic sense to scrap the aircraft and sell the parts rather than (trying to) sell the aircraft itself.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-11T23:32:43.667" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20873" PostTypeId="2" ParentId="20869" CreationDate="2015-09-11T23:55:10.653" Score="13" Body="&lt;p&gt;The 'triangle' wing design that you refer to is pretty common. It is called the &lt;em&gt;delta&lt;/em&gt; wing design and is used in a number of high speed aircraft, for example, the North American XB70 Valkyrie.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QUlbz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QUlbz.jpg&quot; alt=&quot;XB 70&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, the SR 71 wing planform is also a delta, if one removes the engines. One of the reasons is that the wings of the aircrafts are kept inside the Mach cone formed by the aircraft. The Mach angle is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\mu = sin^{-1} \frac{1}{M}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where M is the Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft speed increases, the Mach angle decreases, which means that the aspect ratio should become smaller and smaller. At hypersonic speeds, the delta wing (or a modified one) is the best option as the wing needs to be pretty short for aerodynamics and structural reasons while able to carry the required fuel and generate lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage of the SR-71 Blackbird is its speed, which was about Mach 3.3. It is logical that its replacement should have better speed characteristics. SR 71 used a ramjet during its high speed dash, while its (rumored) successor is expected to use a scramjet engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JdKqD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JdKqD.png&quot; alt=&quot;Engine types&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Turbo_ram_scramjet_comparative_diagram.svg#/media/File:Turbo_ram_scramjet_comparative_diagram.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turbo ram scramjet comparative diagram&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:GreyTrafalgar&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:GreyTrafalgar&quot;&gt;GreyTrafalgar&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first one(a) is a turbojet engine, the second one(b) is ramjet, and the third one(c), a scramjet. The ramjet and scramjet engines are similar, though the combustion happens at supersonic speeds in the scramjet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA has a hypersonic aircraft for experimental purposes called the X43,which uses a scramjet engine, though the aircraft size is pretty small compared to the A340.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ITcWX.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ITcWX.gif&quot; alt=&quot;X 43&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: hapb-www.larc.nasa.gov&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest actual aircraft have come to the shape of the 'Aurora' are the experimental aircraft like the X-37, which has short wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lIjHb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lIjHb.jpg&quot; alt=&quot;X 37&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Boeing_X-37B_inside_payload_fairing_before_launch.jpg#/media/File:Boeing_X-37B_inside_payload_fairing_before_launch.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing X-37B inside payload fairing before launch&lt;/a&gt;&quot; by US Air Force - &lt;a href=&quot;http://www.af.mil/News/Photos.aspx?igphoto=2000374856&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.af.mil/News/Photos.aspx?igphoto=2000374856&lt;/a&gt; (direct link). Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of aircraft with triangular wings, most notably almost all European combat aircraft have delta wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And by the way, the Lockheed Martin SR 72 Aurora concept looks like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZF3Dt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZF3Dt.png&quot; alt=&quot;SR 72&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Lockheed_Martin_SR-72_concept.png#/media/File:Lockheed_Martin_SR-72_concept.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin SR-72 concept&lt;/a&gt;&quot; by Source (WP:NFCC#4). Licensed under Fair use of copyrighted material in the context of Lockheed Martin SR-72&quot; href=&quot;//en.wikipedia.org/wiki/File:Lockheed_Martin_SR-72_concept.png&quot;&gt;Fair use via &lt;a href=&quot;//en.wikipedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-14T16:30:03.067" LastActivityDate="2015-09-14T16:30:03.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20874" PostTypeId="1" CreationDate="2015-09-12T00:52:30.697" Score="5" ViewCount="1933" Body="&lt;p&gt;I was going through the air crash record and found out that a lot of them happened when the aircraft stalled at a low enough altitude where the pilots couldn't get enough speed to pull back out. I was curious to see why this was the case when I learned about flow separation hysteresis where to reattach the flow the wing needs to pitch down further than the static stall angle. Reading that and the crash record brought up a question in my mind:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How could an aircraft be engineered to have safe low altitude stall recovery? (aside from having a VERY low wing loading, ballistic parachutes, or a computer to prevent pilots from entering low altitude stalls) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a cursory analysis, this situation seems ideal for some form of emergency engine, either electrically powered fans or a few solid rocket motors to right the aircraft and provide enough power to at least make the touchdown not a crash. Or the wing and stabilizers have some form boundary layer acceleration to reduce the amount of time needed to recover from a stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious to see what approaches have been tried to try and solve this problem or if the newer aircraft have some other technology incorporated. &lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2021-05-07T01:24:34.967" Title="How can an airliner have low altitude stall recovery?" Tags="&lt;safety&gt;&lt;emergency&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20875" PostTypeId="1" AcceptedAnswerId="20881" CreationDate="2015-09-12T01:11:47.157" Score="11" ViewCount="1011" Body="&lt;p&gt;I've asked around, and it seems all flight training programs use a combination of flight simulators and aircraft flights to train pilots. This works well for most pilots who fly airliners which don't spend much time in turbulent air or close to obstacles, and the flight simulator aerodynamics are very close to what is experienced in actual flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is where do the flight simulator aerodynamics models breakdown? I was wondering this in relation to rough air flying skills, where the aircraft or helicopter flow field interacts with surrounding environment (like inside a convective storm or near obstacles like trees and buildings) I would imagine these are situations that are hard to model since it depends on accurately modelling the interactions, which are difficult to run quickly enough for running a flight simulator. Fixing this by only doing flight training seems dangerous, especially for newbie pilots since the margin for error is very slim. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, even though its more expensive than a flight simulator, a first person view drone would be a good intermediate step between the flight simulator and full scale training, with the response characteristics and control interface being the same as the full scale aircraft or helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, I don't know where the flight simulator aerodynamics begin to diverge from what is actually is experienced in real life, so the drone might be completely unnecessary. I'd love to see how this problem is resolved now. &lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2017-05-25T07:45:17.260" Title="What are the limitations of the aerodynamics modelling used in flight simulators?" Tags="&lt;flight-simulator&gt;&lt;fluid-mechanics&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20876" PostTypeId="2" ParentId="20874" CreationDate="2015-09-12T01:18:05.573" Score="8" Body="&lt;p&gt;The most important reason for aircraft stalls is due to high angle of of attack, which causes flow separation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usual stall recovery procedures consist of reducing the aircraft angle of attack (pitch angle) and increasing power so that the stalled wing starts producing lift and the aircraft forward speed is increased to the required amount. Then the controls are applied in such a way to return to level flight as soon as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with low altitude stall is that stall recovery usually involves some loss of altitude and if the altitude is low enough, recovery from stall &lt;em&gt;may not be possible&lt;/em&gt; before contact with ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However,the recovery altitude may be decreased to a certain extent by incorporating the following technologies in civil aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Use of high lift devices- Use of high lift devices like slats and flaps increases the lift coefficient and also delays the onset of stall. In case the slats have not been deployed before stall, they can be deployed to get the airfoil (wing) produce lift again.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g5a37.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g5a37.gif&quot; alt=&quot;High lift devices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: zenithair.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Increasing the power- In general, greater the power applied, the less the loss of altitude. In this case, the engines usually have excess emergency power that can be applied for reducing the loss of altitude.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, it is better not to enter into a stall and most of the technologies are geared up towards prevention of stall than recovery due to a number of reasons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of civil aircraft, below a certain altitude, stall recovery is usually not possible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Addition of systems to ensure a soft landing in case of stall increases the cost and complexity and in any case may be impracticable in case of large aircraft. As such, it is better to train the pilots to prevent entering into a stall in first place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-12T01:18:05.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20877" PostTypeId="1" CreationDate="2015-09-12T01:26:43.283" Score="7" ViewCount="7489" Body="&lt;p&gt;Can you please give me some examples of warning and restricted areas?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can an aircraft enter these areas? What are the procedures you have to follow before entering them?&lt;/p&gt;&#xA;" OwnerUserId="11193" LastEditorUserId="167" LastEditDate="2015-09-12T16:21:37.043" LastActivityDate="2019-03-29T04:33:38.447" Title="What are some examples of warning areas and restricted areas?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;notam&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20878" PostTypeId="1" CreationDate="2015-09-12T01:44:36.163" Score="4" ViewCount="1130" Body="&lt;p&gt;I'm aware that I can look at the Wikipedia entry for an aircraft and discover specifications like the MTOW, length, cruise speed, etc. However, I was wondering whether there is a (preferably free) source of all this data combined for most aircraft. Does such a data source exist? &lt;/p&gt;&#xA;" OwnerUserId="558" LastEditorUserId="167" LastEditDate="2015-09-12T16:40:24.840" LastActivityDate="2019-03-29T13:49:08.223" Title="Is there a comprehensive source for aircraft specification data for most of the aircraft in the world?" Tags="&lt;aircraft-performance&gt;&lt;datasets&gt;" AnswerCount="4" CommentCount="11" ClosedDate="2019-03-29T15:20:09.957" ContentLicense="CC BY-SA 3.0" />
  <row Id="20879" PostTypeId="2" ParentId="20878" CreationDate="2015-09-12T02:14:18.327" Score="7" Body="&lt;p&gt;You can find a lot of information about aircraft in their Type Certificate Data Sheet that is available from the FAA or other certificating authorities. The FAA's is located &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/Frameset?OpenPage&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. It takes a bit of time to find certain things, and other things aren't included like range, or sometimes dimensions.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-09-12T02:14:18.327" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20881" PostTypeId="2" ParentId="20875" CreationDate="2015-09-12T10:07:29.107" Score="11" Body="&lt;p&gt;Size matters here. Big aircraft have more inertia and take much longer to respond, but can equal out small-scale turbulence better. Your drone idea for training will not be representative of the big airplane at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbulence can be modeled quite faithfully - you just need to fly once through rough air, collect all the data and replay it in the simulator. The changes due to different pilot responses can be added on top without much loss in accuracy against a real flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where models for airliner crew training break down is when the linear range of aerodynamics is left. Their post-stall and spin behavior is most likely not suitable for training, but that is not what they are designed for. Military aircraft simulators can even model the post-stall regime well, but need a lot of aerodynamic data, and most of that data is from &lt;a href=&quot;http://www.bihrle.com&quot;&gt;wind tunnel models&lt;/a&gt; and not from real flight test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the simulation does is to plug the actual values of angle of attack, angle of sideslip, airspeed, power level angle and control deflections into matrices of coefficients and calculate the result from linear addition. That works well as long as the forces vary linearly of the flow angles, and correction factors will give you still good agreement with reality well into a stall. The coefficients are a mixture of &lt;a href=&quot;https://en.wikipedia.org/wiki/Computational_fluid_dynamics&quot;&gt;CFD&lt;/a&gt;, wind tunnel data and flight test data. Gust loads can be modeled with &lt;a href=&quot;https://en.wikipedia.org/wiki/Stochastic_matrix&quot;&gt;Markov matrices&lt;/a&gt; which produce a realistic distribution of gust intensities, so even external, stochastic factors can be modeled faithfully.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have less knowledge of helicopter simulators, and I would assume that flying near tall buildings can only be modeled in general terms, but not well enough to train a pilot for a specific location and weather condition.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-12T10:12:36.703" LastActivityDate="2015-09-12T10:12:36.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20882" PostTypeId="2" ParentId="20874" CreationDate="2015-09-12T11:29:05.557" Score="5" Body="&lt;p&gt;The main solution to speed up stall recovery has been to install more powerful engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stall is a total energy problem. If the aircraft is low, it has little potential energy left to top up its kinetic energy, and a stall is exactly when the kinetic energy drops below the value needed for staying in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you correctly note, the boundary layer needs some time to recover, and the further back on the wing you look, the more the boundary layer is shaped by what went on before. This helps to &lt;a href=&quot;https://aviation.stackexchange.com/questions/14236/is-there-always-a-stall-if-you-exceed-a-specific-angle-of-attack/14257#14257&quot;&gt;delay stall when the pitch rate is sufficiently high&lt;/a&gt;, but makes recovery take longer. Boundary layer suction would certainly help, but all cases of suction which I know of were either installed to &lt;a href=&quot;https://aviation.stackexchange.com/questions/13762/is-there-a-maximum-lift-to-drag-ratio/13767#13767&quot;&gt;keep the flow laminar for longer&lt;/a&gt; or to delay separation at high angle of attack. The suction volume needed to speed up stall recovery is a magnitude above that needed for delaying stall, so even when suction was installed, it would have been insufficient for shortening the stall recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea of quickly adding kinetic energy is much more promising, and your proposal of a rocket engine will certainly help. If it points slightly upwards, it can compensate for the lift loss during stall and speed up the airplane so it returns quickly to the linear flight regime. The same can be achieved with sufficiently powerful engines, and since they are much more fuel efficient than rockets, they have been preferred over rockets to make fighter and aerobatic aircraft essentially unstallable if their &lt;a href=&quot;http://www.gforceaerobatics.com/about/aircraft/&quot; rel=&quot;nofollow noreferrer&quot;&gt;thrust-to-weight ratio approaches one&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, a benign lift curve slope at stall can be engineered into the wing by using a big nose radius, a linear &lt;a href=&quot;https://aviation.stackexchange.com/questions/20792/does-the-piper-pa-28-cherokee-wing-have-laminar-flow-behavior/20795?s=1%7C0.2219#20795&quot;&gt;pressure recovery gradient&lt;/a&gt; and washout, so the outer wing still has attached flow when the inner wing stalls. The first two factors help to keep lift fairly constant well into the stall, so vertical acceleration is low. The third factor ensures proper aileron response and low roll moments due to flow separation, so the aircraft will not divert and stays controllable. The drag increase due to separation, however, will decelerate the aircraft and lead to a loss of lift if the stall is not ended quickly. The benign lift curve slope of the wing made the stall in case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;AF447&lt;/a&gt; so uneventful that the copilot never realized that he had pulled the aircraft into a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, most aircraft are flown such that they never enter into a stall. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2317/how-does-an-alpha-aoa-vane-work&quot;&gt;Instrumentation&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/9268/how-reliable-are-stick-shakers&quot;&gt;warning devices&lt;/a&gt; will prevent even incompetent pilots from stalling the aircraft unless they intend to do so, eliminating the need for emergency rockets or oversized engines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-12T12:37:29.290" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20883" PostTypeId="2" ParentId="20875" CreationDate="2015-09-12T11:31:27.690" Score="11" Body="&lt;p&gt;There are two aspects to simulation error: the aerodynamic model error and less commonly known, integration algorithm numerical error. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerodynamic models tend to break down in the transonic and post stall regime of flight for two reasons: lack of data due to safety or cost, and poor predictability created by non-linear response in turbulent flow/shockwave formation. That is, the risk to reward would prohibit the conduct of full post stall(spin) test program on a wide body airliner. There is no justifiable reason to do so in relation to the aircraft's role or certification requirements. Contrast this to a fighter jet that might require this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Buffet, ground effect, external turbulence, and wake turbulence can all be simulated with reasonable accuracy according to the requirements and complexity of the sim, which is dictated by the aircraft role. Note that buffet can occur prestall. Despite the difficulties in predicting post stall handling qualities using tools such a CFD analysis, it is possible to collect reasonable data in relation to handling characteristics with detailed and thorough flight test. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simulators are usually hamstrung by model complexity and realtime computing power.  For that reason,  integration algorithms are chosen to best suit the simulation application. Airliner sims tend to use forward predictive algorithms such as Adams-Bashforth-Moulton predictors, as the flight envelope is limited to regions where strong linearity exists. Conversely  this algorithm would induce significant errors even if reasonable aerodynamic data existed in post stall, spinning flight. Other algorithms do exist and are better suited for this application. Brute force may also be an option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a drone could be beneficial, however it would be difficult to accurately mimic moments of inertia characteristics, and post stall handling due to Reynolds effects. Ok for generic simulation, but not ok when replicating larger scaled aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8030" LastActivityDate="2015-09-12T11:31:27.690" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20884" PostTypeId="2" ParentId="20877" CreationDate="2015-09-12T13:07:14.107" Score="9" Body="&lt;p&gt;I'll provide information for the US airspace. However many countries, ICAO members, will have similar concepts and procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are not required to follow any procedure for entering a warning area or an &lt;em&gt;inactive&lt;/em&gt; restricted airspace. In the latter case, you need to ensure the area is actually inactive. A safe practice is to contact the controlling agency of the area prior to enter any warning or restricted one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer answer below develops a bit around &lt;em&gt;special use airspaces&lt;/em&gt; which encompass &lt;em&gt;warning&lt;/em&gt; and &lt;em&gt;restricted&lt;/em&gt; airspaces among other. You'll also find two examples of these areas.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Context&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airspace over the US is open to navigation, &lt;a href=&quot;https://en.wikipedia.org/wiki/Controlled_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;a part of this airspace&lt;/a&gt; benefit from services provided by air traffic control (ATC), e.g. safe separation and traffic information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This controlled airspace includes airport areas and airways, and other areas of interest. It is is ruled by air regulations relative to &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspace_class&quot; rel=&quot;nofollow noreferrer&quot;&gt;airspace classes&lt;/a&gt;. In the US these regulations are found in document &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&quot; rel=&quot;nofollow noreferrer&quot;&gt;94 CFR 91&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rs2H4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rs2H4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://community.infinite-flight.com/t/class-alpha/1698&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some limited areas, that may be permanent or temporary, can be prohibited or restricted. Together they constitute the &lt;a href=&quot;https://en.wikipedia.org/wiki/Special_use_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;special use airspaces&lt;/a&gt; (SUA)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Special use airspaces&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SUA (&lt;a href=&quot;https://en.wikipedia.org/wiki/Special_use_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Special use airspace includes: restricted airspace, prohibited&#xA;  airspace, military operations areas (MOA), warning areas, alert areas,&#xA;  temporary flight restriction (TFR), national security areas, and&#xA;  controlled firing areas.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The SUA are repertoried by the FAA: &lt;a href=&quot;http://sua.faa.gov/sua/siteFrame.app&quot; rel=&quot;nofollow noreferrer&quot;&gt;SUA Web site&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may search by name or scan the map. R denotes a restricted airspace, and W a warning area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/52GnV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/52GnV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g12No.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g12No.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More on SUA: &lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/42/565/Airspace,%20Special%20Use%20Airspace%20and%20TFRs%20-%20Text%20Only.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Course Notes, Dennis Seals, FAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question is limited to warning areas and &lt;a href=&quot;https://en.wikipedia.org/wiki/Restricted_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;restricted&lt;/a&gt; airspace.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Restricted airspace&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Restricted_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Restricted areas denote the existence of unusual, often invisible,&#xA;  hazards to aircraft such as artillery firing, aerial gunnery, or&#xA;  guided missiles. Penetration of restricted areas without authorization&#xA;  from the using or controlling agency may be extremely hazardous to the&#xA;  aircraft and its occupants.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also chapter 3−4−3. Restricted Areas of the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA-AIM&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Entry: Forbidden when active, subject to ATC clearance on a case by case basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For areas that have a scheduled activity, times of activation are published in the AIP. When inactive, a R-area is just a like any other location of the surrounding airspace class. When active it is just forbidden to enter it (albeit FAA may deliver specific clearances if solicited).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For VFR flights, contacting ATC prior to entering an inactive restricted area is not mandatory per regulations, but is a good practice regarding safety. IFR flights under monitoring of the ATC, will not be authorized to enter an active restricted area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Restricted_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Restricted airspace zones may not be active at all times; in such&#xA;  cases there are typically schedules of local dates and times available&#xA;  to aviators specifying when the zone is active, and at other times,&#xA;  the airspace is subject to normal VFR/IFR operation for the applicable&#xA;  airspace class.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Activity time may happen unscheduled for some R-areas. A schedule cannot be published, in this case a &lt;a href=&quot;https://en.wikipedia.org/wiki/NOTAM&quot; rel=&quot;nofollow noreferrer&quot;&gt;NOTAM&lt;/a&gt; is used to inform airspace users.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Restricted_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A few zones are activated by NOTAM; an example is R-2503D over Camp&#xA;  Pendleton in southern California, between San Diego and Los Angeles.&#xA;  This particular zone, beginning at 2000ft above sea level over most of&#xA;  southern Camp Pendleton, can only be active for a certain number of&#xA;  days per year, thus allowing small planes to fly a direct route over&#xA;  land between the two metro areas instead of being diverted offshore or&#xA;  into mountainous terrain further inland.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Example: Restricted areas R-2501 around the &lt;a href=&quot;http://www.29palms.marines.mil/Portals/56/Docs/G5/special%20use%20airspace.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Twentynine Palms Marine Corps Air Ground Combat Center&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/REqRM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/REqRM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.globalsecurity.org/military/facility/moa-29palms.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;GlobalSecurity.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Twentynine Palms Complex is located in the Southern California&#xA;  desert approximately 115 NMI northeast of Los Angeles, CA. The&#xA;  Twentynine Palms Complex provides a vast land and restricted airspace&#xA;  (R-2501) area for live ordnance employment and combined arms training&#xA;  of infantry units, armored vehicles, artillery, and air support.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The complex includes the following instrumented area: R-2501E&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The following are training, and Military Operating Areas (MOAs)&#xA;  associated with the Twentynine Palms complex:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;R-2501N&lt;/li&gt;&#xA;  &lt;li&gt;R-2501W&lt;/li&gt;&#xA;  &lt;li&gt;R-2501S&lt;/li&gt;&#xA;  &lt;li&gt;Bristol MOA&lt;/li&gt;&#xA;  &lt;li&gt;Sundance MOA&lt;/li&gt;&#xA;  &lt;li&gt;Range Training Areas (RTA)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Description of R-2501N from &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400.8SBasic.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Order JO 7400.8S&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R-2501N Bullion Mountains North, CA &#xA;Boundaries.&#xA;Beginning at lat. 34°30'00&quot;N., lon g. 116°26'23&quot;W.;&#xA;to lat. 34°36'00&quot;N., long. 116°28'03&quot;W.;&#xA;to lat. 34°40'30&quot;N., long. 116°29'43&quot;W.;&#xA;to lat. 34°43'00&quot;N., [...]&#xA;Designated altitudes. Unlimited.&#xA;Time of designation. Continuous.&#xA;Controlling agency. FAA, Los Angeles ARTCC.&#xA;Using agency. Commanding General, Marine Corps Base, Twentynine Palms, CA.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This area around a large military complex is active (restricted) 24x7, at any altitude. A pilot who wants to enter this area for some reason needs to contact either the controlling agency (Los Angeles ARTCC) or the using agency (Marine Corps Base).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Warning area&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chapter 3−4−4. Warning Areas of the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA-AIM&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A warning area is airspace of defined dimensions, extending  from&#xA;  three nautical miles outward from the coast of the U.S., that contains&#xA;  activity that may be hazardous to nonparticipating aircraft. The&#xA;  purpose of such warning areas is to warn nonparticipating pilots  of&#xA;  the potential danger. A warning area may be located  over domestic or&#xA;  international waters or both.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Entry without specific clearance, but can be hazardous. Contacting ATC prior to entering a warning area is not mandatory per regulations, but is a good practice regarding safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: Pacific Missile Range Facility (PMRF) NS Barking Sands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vc6rX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vc6rX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.globalsecurity.org/military/facility/pmrf.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;GlobalSecurity.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The area surrounding Kauai is divided into warning areas with W-186&#xA;  and W-188 controlled by PMRF. The Fleet Area Control and Surveillance&#xA;  Facility (FACSFAC) controls W-187, 189, and 190. Space, air, and&#xA;  surface tracking are accomplished from PMRF precision-tracking radar&#xA;  sites at elevations of 75 ft., 1700 ft., and 3800 ft. These are&#xA;  supported by radar systems operated by agencies external to PMRF.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Description of W-188 from &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400.8SBasic.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Order JO 7400.8S&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;W-188 Hawaii, HI &#xA;Boundaries. Beginning at lat. 21°58'19&quot;N., long. 159°48'45&quot;W.;&#xA;to lat. 21°58'27&quot;N., long. 159°59'50&quot;W.; [...]&#xA;Altitudes. Surface to unlimited. &#xA;Times of use. Continuous. &#xA;Controlling agency. FAA, FAA, Honolulu Control Facility. &#xA;Using agency. Commander, Pacific Missile Range Facility, HI. &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;More:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Related question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/13234/can-a-pilot-fly-through-a-restricted-area-while-flying-on-a-victor-airway&quot;&gt;Can a pilot fly through a restricted area while flying on a Victor Airway?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2018-02-09T19:49:23.107" LastActivityDate="2018-02-09T19:49:23.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20887" PostTypeId="2" ParentId="19304" CreationDate="2015-09-12T16:09:20.113" Score="30" Body="&lt;h3&gt;Short answer&lt;/h3&gt;&#xA;&lt;p&gt;These are the three redundant temperature sensors for the windscreen anti icing and defogging system. The design is similar to what is found on the A330 and A340, and most large aircraft. The sensors are used to control the electric current in the heating film(s) sandwiched in the windscreen ply. Usually three temperatures are monitored:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Outer windscreen layer must be above freezing point, e.g. 1.8°C.&lt;/li&gt;&#xA;&lt;li&gt;Film mustn't overheat, depends on film used.&lt;/li&gt;&#xA;&lt;li&gt;Inner layer must be below some threshold, e.g. 50°C.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/mzostudio/videos/2763004477259722/&quot; rel=&quot;nofollow noreferrer&quot;&gt;This video&lt;/a&gt; shows how windscreen heating works on an ATR42. Extract related to the sensors:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yMlMn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yMlMn.jpg&quot; alt=&quot;ATR42 windscreen temperature sensors and film bus bars&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;ATR42 windscreen temperature sensors and film bus bars&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The heating film(s) is/are used both to prevent icing and failure of the outer panel (air temperature can be as low as -60°C) and fogging on the inner panel. This can be obtain using a single film, but sometimes there are two distinct films:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dMMBf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dMMBf.png&quot; alt=&quot;Structure of the windscreen on a Boeing 787&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Structure of the windscreen on a Boeing 787. &lt;a href=&quot;https://thepointsguy.com/news/what-are-airplane-windows-made-of/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;On the A350&lt;/h3&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.scribd.com/doc/269894568/30-Ice-and-Rain-Protection-pdf#scribd&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-350 Technical Training Manual&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KeFwS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KeFwS.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Windows Anti Icing/Defogging Function, Description and Interfaces&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The windows anti icing/defogging system is divided into two&#xA;sub-systems (F/O and CAPT). Each sub-system is comprised of one&#xA;windshield, one FWD lateral window, one AFT lateral window and a&#xA;Window Heat Computer (WHC). [...]&lt;/p&gt;&#xA;&lt;p&gt;The anti icing and defogging function of the cockpit&#xA;windshields is ensured by the heating of one resistive/heating ﬁlm. Each&#xA;windshield's resistive heating ﬁlm is powered by 230 VAC, provided by&#xA;the WHC.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;There are three temperature sensors near the heating ﬁlm&lt;/strong&gt; that&#xA;continually send information to the WHC for the heating regulation and&#xA;the overheat protection functions. [...]&lt;/p&gt;&#xA;&lt;p&gt;The WHC regulates the temperature of the cockpit windows (35 degrees C to&#xA;42 degrees C) based on the temperature value it receives from one of the three temperature sensors. The other two temperature sensors are&#xA;in standby mode. [...]&lt;/p&gt;&#xA;&lt;p&gt;If the temperature of the cockpit windows reaches a specific&#xA;temperature level (+60 degrees C), the WHC will stop supplying the&#xA;specific window. [...] For each window, the WHC uses temperature&#xA;values from the three temperature sensors to detect an overheat.&lt;/p&gt;&#xA;&lt;p&gt;The WHCs interface and exchange data via CRDCs with the&#xA;AFDX network.The two WHCs are located in the cockpit: WHC1 is located&#xA;next to the fourth occupant console behind the Captain. WHC2 is&#xA;located next to the coat stowage behind the First Ofﬁcer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For this test aircraft:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sensors are larger than usual.&lt;/li&gt;&#xA;&lt;li&gt;They may be stuck on the glass instead of being built-in.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This setting might be specific for flight test purposes. Someone may bring additional elements.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Another example, on a &lt;a href=&quot;http://www.planes.cz/cs/photo/1123348/pilatus-pc-12ng-ok-pca-private-mimo-letiste&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilatus PC12-NG&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vw8Ww.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vw8Ww.jpg&quot; alt=&quot;Pilatus PC12-NG temperature sensors and bus bars on the windscreen&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Pilatus PC12-NG temperature sensors and bus bars on the windscreen&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-06-28T10:38:47.330" LastActivityDate="2020-06-28T10:38:47.330" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="20888" PostTypeId="2" ParentId="20878" CreationDate="2015-09-12T16:37:14.337" Score="5" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m6zBE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m6zBE.jpg&quot; alt=&quot;Jane&amp;#39;s All The World&amp;#39;s Aircraft - Cover Photo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0710629559&quot; rel=&quot;noreferrer&quot;&gt;Jane's All The World's Aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not free (Amazon lists it for between \$500 and \$1,000 USD) and it's not machine-readable, but yes, the data is out there.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-09-12T16:37:14.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20890" PostTypeId="1" AcceptedAnswerId="20891" CreationDate="2015-09-12T18:09:52.617" Score="10" ViewCount="1217" Body="&lt;p&gt;Specifically, I'm a little confused about Sec 91.175(c)(3)(i) which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The approach light system, except that the pilot may not descend below&#xA;  100 feet above the touchdown zone elevation using the approach lights&#xA;  as a reference unless the red terminating bars or the red side row&#xA;  bars are also distinctly visible and identifiable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From what I understand, I'm allowed to descend up to 100ft above the touch down zone elevation (TDZE) if I'm able to see and identify the red terminating bars on the approach light systems (ALS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what happens when the ALS does not have the red terminating bars (for e.g. MALSR and MALSF)? Do I maintain my MDA even if I have part of the ALS in sight?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="19" LastEditDate="2017-01-25T10:31:58.063" LastActivityDate="2017-01-25T10:31:58.063" Title="When can I descent below the MDA if the approach light system does not have red terminating bars?" Tags="&lt;faa-regulations&gt;&lt;approach&gt;&lt;far-91&gt;&lt;descent&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20891" PostTypeId="2" ParentId="20890" CreationDate="2015-09-12T20:11:07.520" Score="10" Body="&lt;p&gt;You can descend down to 100ft above TDZE if you have &lt;em&gt;any&lt;/em&gt; ALS in sight. You need an ALS with red lights (ALSF I &amp;amp; II) to go below that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Red terminating bars/red side row bars help you find the threshold. Think of an ALS with red lights as being in the same category as Runway/lights/markings, Threashold/lights/markings, Touchdown Zone/lights/markings, VASI/PAPI, and REIL. Any other type of ALS (MALSR, MALSF, etc.) has the 100ft above TDZE restriction put on it when it is the only thing you can see.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@mins linked to a couple of helpful articles in the comments.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-09-12T20:11:07.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20892" PostTypeId="2" ParentId="568" CreationDate="2015-09-12T23:03:23.533" Score="14" Body="&lt;p&gt;The most direct answer to your question has little to do with physics and a lot to do with a typical pilot's understanding of how a piston engine works.  The manufacturers specify ROP because it's &amp;quot;easy.&amp;quot;  Most pilots (myself included, over the course of 2900 hrs of flying) were not exposed to the &lt;em&gt;whys&lt;/em&gt; of proper engine operation during training.  We were all taught the &amp;quot;LOP = burned valves&amp;quot; which simply isn't true.  The manufacturers compensate for this lack of understanding by oversimplifying engine operation directions to keep us safe from ourselves.&lt;/p&gt;&#xA;&lt;p&gt;Contrary to popular belief, LOP is not bad for piston engines.  What &lt;em&gt;is&lt;/em&gt; bad is mixture setting within what is commonly referred to as the &amp;quot;red box.&amp;quot;  Running LOP safely requires you to lean further than what most standard fuel injectors can support.  Leaning with unbalanced (&amp;quot;standard&amp;quot;) injectors will eventually lead to a rough running engine that would otherwise run just fine ROP.  This is where Gami or Continental balanced injectors become necessary.  They are precision injectors that allow you to lean far enough LOP while still delivering even amounts of fuel to each cylinder to keep the engine running smoothly (oversimplified).  Google &amp;quot;mixture setting redbox&amp;quot; to get started.  Note that you can be ROP and still inside the red box.  ROP alone is no guarantee that you're running the engine properly.&lt;/p&gt;&#xA;&lt;p&gt;There is a TON of research out there that will lead you to the conclusion that LOP is not bad when set properly (just as ROP is fine when set properly).  In fact, in most cases the engine will run cooler and cleaner LOP than an identical engine run ROP.  Mine does.&lt;/p&gt;&#xA;&lt;p&gt;I strongly recommend that you read the following several times:&lt;br /&gt;&#xA;&lt;a href=&quot;https://www.avweb.com/features/avweb-classics/pelicans-perch/pelicans-perch-63where-should-i-run-my-engine-part-1/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pelican’s Perch #63: Where Should I Run My Engine? (Part 1)&lt;/a&gt;&lt;br /&gt;&#xA;&lt;a href=&quot;https://www.avweb.com/features/avweb-classics/pelicans-perch/pelicans-perch-64where-should-i-run-my-enginepart-2-the-climb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pelican’s Perch #64: Where Should I Run My Engine? (Part 2 – The Climb)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;There is a third article in the series but the site won't let me post it...need more reputation!&lt;br /&gt;&#xA;(edit: &lt;a href=&quot;https://www.avweb.com/features/avweb-classics/pelicans-perch/pelicans-perch-65where-should-i-run-my-enginepart-3-cruise/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pelican’s Perch #65: Where Should I Run My Engine? (Part 3 – Cruise)&lt;/a&gt;) +&lt;br /&gt;&#xA;(edit: &lt;a href=&quot;https://www.avweb.com/features/avweb-classics/pelicans-perch/pelicans-perch-66where-should-i-run-my-enginepart-4-descent/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pelican’s Perch #66: Where Should I Run My Engine? (Part 4 – Descent)&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;I fly my IO-520 LOP in cruise (waaaay ROP in the climb) and see about 1.5gph savings compared to my POH fuel burn.  It costs three or four knots but that's a fair trade!  My 1470 hour Continental clyinders hold great compression and I burn very little oil.  I use an EDM700 engine monitor and Gamis.  Do not be afraid of LOP, just learn how to do it correctly!&lt;/p&gt;&#xA;&lt;p&gt;Happy flying!&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="19560" LastEditDate="2020-09-05T15:30:39.960" LastActivityDate="2020-09-05T15:30:39.960" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="20896" PostTypeId="2" ParentId="9722" CreationDate="2015-09-13T03:36:55.977" Score="1" Body="&lt;p&gt;I don't know about civilian aircraft, but it's true that military aircraft have specific patterns. Each aircraft role flashes differently. Ill use F-18s as an example because they are multirole. An F-18 tanker might flash &lt;strong&gt;*, where an F-18 strike fighter might flash like *-&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both same aircraft but different jobs, hence different patterns&lt;/p&gt;&#xA;" OwnerUserId="11203" LastActivityDate="2015-09-13T03:36:55.977" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20897" PostTypeId="1" CreationDate="2015-09-13T09:37:25.260" Score="-5" ViewCount="6873" Body="&lt;p&gt;How can a plane withstand the safety factor of 2.5?&lt;/p&gt;&#xA;" OwnerUserId="11204" LastEditorUserId="1289" LastEditDate="2015-09-14T10:23:06.797" LastActivityDate="2015-09-14T10:23:06.797" Title="Safety factor in aircraft design" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-09-13T12:02:12.750" ContentLicense="CC BY-SA 3.0" />
  <row Id="20898" PostTypeId="2" ParentId="20897" CreationDate="2015-09-13T10:11:46.283" Score="5" Body="&lt;p&gt;Safety factor describes the structural capacity of a system beyond the expected loads or actual loads. So, safety factor gives how much the system is stronger (i.e. how much load it can take before failure) compared to the expected load on the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ Safety \ Factor = \frac {Maximum \ load \ before \ failure}{Design \ load}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Design load, sometimes called the limit load is the maximum amount of load the part is expected to face in service. In aviation, the FAR Part 25 deals with safety in §25.303   Factor of safety, which says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Unless otherwise specified, a factor of safety of 1.5 must be applied to the prescribed limit load which are considered external loads on the structure. When a loading condition is prescribed in terms of ultimate loads, a factor of safety need not be applied unless otherwise specified. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As can be seen, the safety factor is the structural load for which the system has been &lt;em&gt;designed&lt;/em&gt;, not a load that &lt;em&gt;actually acts on the system&lt;/em&gt;. The main reasons for having a factor of safety are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Loads may be high in certain unexpected situations (like emergency)&lt;/li&gt;&#xA;&lt;li&gt;The structure may undergo wear and tear and my degrade over time.&lt;/li&gt;&#xA;&lt;li&gt;The structure may be loaded beyond the expected loads inadvertently.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Except in unusual circumstances, the aircraft &lt;em&gt;will not to withstand&lt;/em&gt; any safety factor; rather is is &lt;em&gt;designed to withstand&lt;/em&gt; safety factor times the maximum expected load. The figure of 2.5 is too high for safety factor in aviation and has not been used in any aircraft to the best of my knowledge due to the exorbitant weight penalty involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term used for withstanding of load is called &lt;em&gt;load factor&lt;/em&gt;, which is given as the ratio of aerodynamic load perpendicular to longitudinal axis to the aircraft weight.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-13T10:11:46.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20899" PostTypeId="1" AcceptedAnswerId="20908" CreationDate="2015-09-13T11:35:35.523" Score="16" ViewCount="2990" Body="&lt;p&gt;In my understanding, &quot;F&quot; stands for &quot;fighter&quot; (air-to-air) and &quot;A&quot; for &quot;attack&quot; (air-to-ground). E.g.,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;the F/A-18 Hornet can attack air &lt;em&gt;and&lt;/em&gt; ground targets, which is why it's called &lt;strong&gt;F/A&lt;/strong&gt;-18.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the A-10 Warthog is used as an attack aircraft, which is why it's called &lt;em&gt;A&lt;/em&gt;-10. However, it's also capable of attacking air targets using IR missiles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15E_Strike_Eagle&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-15E Strike Eagle&lt;/a&gt; is also capable of attacking air &lt;em&gt;and&lt;/em&gt; ground targets. So why is the Strike Eagle still called F-15E and not F/A-15?&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="1696" LastEditDate="2018-04-12T14:19:14.143" LastActivityDate="2018-04-12T19:37:40.097" Title="Why isn't the F-15E called F/A-15?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;&lt;aircraft-naming&gt;&lt;f-15&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20902" PostTypeId="2" ParentId="20899" CreationDate="2015-09-13T13:39:38.877" Score="7" Body="&lt;p&gt;The F-15A and F-15B came along first, and they were pure air-to-air.  (The B model is two-seat so an instructor or observer could ride along.)  Then the F-15C and F-15D were built, also as pure air-to-air platforms.  (Again, the D model has the back seat while the C is single-seat.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then they got the idea for the &quot;E&quot; model, which has the second seat for the WSO and all the various equipment for ground attack.  But it's still a model of the F-15.  This far into production, it wasn't thought to be necessary to change the designation from F-15 to F/A-15.  Maybe if the &quot;E&quot; had been first and the air-to-air variants had come along later, they might have called it &quot;F/A-15,&quot; but not necessarily.  The F-117 was pure ground attack, and it's an &quot;F&quot; not an &quot;A&quot; like the A-10.  The F-16 has lots of ground attack capability, but it's an &quot;F&quot; not an &quot;F/A&quot; designation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The honest answer is, the Air Force places a low priority on the &quot;purity&quot; of only using the &quot;F&quot; designation on air-to-air platforms and nothing else.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-09-13T13:39:38.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20903" PostTypeId="1" AcceptedAnswerId="20905" CreationDate="2015-09-13T13:44:00.853" Score="13" ViewCount="3708" Body="&lt;p&gt;In a smaller airport which still handles large commercial aircraft (i.e. Princess Juliana Int. Airport (TNCM), Robert L. Bradshaw Int. Airport (TKPK), etc.), what are the taxi instructions given? I don't want to just assume that an airliner would be given a taxi and hold short, but that is what I would expect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a diagram of Bradshaw Airport,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/luaCe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/luaCe.jpg&quot; alt=&quot;Image Copyright Acronautic&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Copyright, &lt;a href=&quot;http://www.acronautic.com/st-kitts-private-jet-terminal/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Acronautic&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say our commercial airliner is taking off from Runway 07. They get a Taxi To and Hold Short instruction preparatory to Cleared To Takeoff. Do they taxi to the end of ramp A and hold short? or do they go all the way to the turn around at the end of 07?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's the end of A, what instruction allows then to enter and use the runway as a taxiway?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2017-01-16T14:07:59.867" LastActivityDate="2017-01-16T14:07:59.867" Title="How are taxi to and hold instructions given on an airport without taxiways to the runway end?" Tags="&lt;airport&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20904" PostTypeId="2" ParentId="20903" CreationDate="2015-09-13T14:04:31.730" Score="14" Body="&lt;p&gt;If they're given a &quot;hold short&quot; instruction, then they &lt;strong&gt;don't&lt;/strong&gt; enter the runway.  That's sacrosanct, since it's what protects the runway from an incursion if an aircraft will soon be using the runway to land or take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instruction to enter the runway but not take off is &quot;line up and wait,&quot; and to go back the length of Runway 7 and turn around is to &quot;back taxi&quot; (FAA term) or &quot;backtrack&quot; (ICAO term, same meaning) on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let's say that an inbound aircraft has landed, and is past (northeast of) taxiway A but is still on the runway.  The aircraft ready to depart can be cleared onto runway 7 to back taxi (or &quot;backtrack&quot;), line up and wait -- but the tower wouldn't issue a takeoff clearance until the entire runway is clear.  But this clearance gets the departing aircraft moving toward the position he wants to be in, and by the time the back taxi is complete, the runway will probably be clear, so a takeoff clearance can be issued at that point.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-09-14T15:56:15.943" LastActivityDate="2015-09-14T15:56:15.943" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20905" PostTypeId="2" ParentId="20903" CreationDate="2015-09-13T14:17:02.293" Score="15" Body="&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; is a taxiway, not the ramp. It will have stop bars and signs at the end. &lt;a href=&quot;http://image.slidesharecdn.com/ar10x96barricadehowtoforconstructionpersonnel-13256200459753-phpapp02-120103135526-phpapp02/95/runway-construction-safety-17-728.jpg?cb=1364820838&quot;&gt;Here&lt;/a&gt;, the double solid lines are on the taxiway side and must not be crossed without clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the instruction is hold short, you hold at the end of Alpha.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NB.  An active runway is never a taxiway.  The clearances and instructions are for runways, even when backtracking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial clearance will likely be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxi via Alpha, hold short runway 07.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Followed by&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Line up runway 07 via backtrack and wait.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then finally:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;cleared for take-off runway 07&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The initial clearance might combine the first 2.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxi via alpha, line up runway 07 via backtrack and wait&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the runway designator is always the departure runway so &lt;code&gt;enter 25 and backtrack&lt;/code&gt; would not be used.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1931" LastEditDate="2015-09-14T09:44:47.623" LastActivityDate="2015-09-14T09:44:47.623" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20908" PostTypeId="2" ParentId="20899" CreationDate="2015-09-13T16:46:31.243" Score="21" Body="&lt;p&gt;The aircraft you are mentioning are completely different from each other and some of them are not even named according to the US &lt;a href=&quot;https://en.wikipedia.org/wiki/1962_United_States_Tri-Service_aircraft_designation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tri service Naming System&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the aircraft retain their original designation given even though the later versions have little in common with their predecessors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F 15 was a direct result of the studies that followed the Vietnam war and the a response to new generation Soviet aircraft like the Mig-25. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rJvG3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rJvG3.jpg&quot; alt=&quot;F-15A&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:McDonnell_Douglas_F-15A_USAF.jpg#/media/File:McDonnell_Douglas_F-15A_USAF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;McDonnell Douglas F-15A USAF&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15 was designed purely as a air superiority fighter, with full emphasis on maneuverability and agility with &quot;Not a pound for air-to ground!&quot;. The first to variants of the F-15 were called F-15 (single seat) and TF-15 (two seat), which were retrospectively named F-15A nd F-15B after the introduction of F-15C. The F-15E was a strike variant; however, it could defend itself against enemy aircraft and thus retained the 'F' title.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QAHp3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QAHp3.jpg&quot; alt=&quot;F-15E&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-15E_Strike_Eagle.jpg#/media/File:F-15E_Strike_Eagle.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-15E Strike Eagle&lt;/a&gt;&quot; by Gerry Metzler - IMG_214. Licensed under CC BY-SA 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The case of F/A-18 is different. The initial plan was to purchase three different version of the aircraft, F-18A (Fighter), A-18A (Attack) and TF-18A (Trainer). However developments in avionics and some design changes led to the &#xA;first two versions joined together as F/A-18A and the trainer version being named F/A-18B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yH8eG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yH8eG.jpg&quot; alt=&quot;F/A-18B&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:%20An_F-A-18B_Hornet,_assigned_to_the_U.S._Naval_Test_Pilot_School,_folds-up_its_landing_gear_after_taking_off_for_a_training_flight_from_Naval_Air_Station_Patuxent_River,_Md.jpg#/media/File:US_Navy_050803-N-0295M-148_An_F-A-18B_Hornet,_assigned_to_the_U.S._Naval_Test_Pilot_School,_folds-up_its_landing_gear_after_taking_off_for_a_training_flight_from_Naval_Air_Station_Patuxent_River,_Md.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;US Navy 050803-N-0295M-148 An F-A-18B Hornet, assigned to the U.S. Naval Test Pilot School, folds-up its landing gear after taking off for a training flight from Naval Air Station Patuxent River, Md&lt;/a&gt;&quot; by U.S. Navy photo by Photographer’s Mate 2nd Class Daniel J. McLain &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the aircraft in service today are multirole and their names mostly reflect what their &lt;em&gt;intended&lt;/em&gt; purpose is rather than their &lt;em&gt;actual&lt;/em&gt; purpose. With modern avionics and high precision weapon systems, almost any aircraft could be made a strike aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is to be noted that the naming convention is followed only loosely in some cases. A good example is the F-117 Nighthawk, which is not a fighter aircraft in any sense of the word.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2018-04-12T19:37:40.097" LastActivityDate="2018-04-12T19:37:40.097" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20909" PostTypeId="1" CreationDate="2015-09-13T21:08:19.880" Score="3" ViewCount="2377" Body="&lt;p&gt;What cancels the rolling moment produced from the rotation of the engine?&lt;/p&gt;&#xA;" OwnerUserId="9201" LastEditorUserId="62" LastEditDate="2016-10-17T19:07:45.297" LastActivityDate="2016-10-17T19:07:45.297" Title="How do propeller-driven, fixed-wing UAVs counter negative torque from engine rotation?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20910" PostTypeId="2" ParentId="20909" CreationDate="2015-09-13T23:38:24.557" Score="2" Body="&lt;p&gt;The design considerations for UAVs are the same as that of other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The torque applied by the motor (or engine) to the propeller causes an equal and opposite torque applied by the propeller to the UAV body. This torque, $T$ is opposite to the propeller rotation and is proportional to the square of propeller angular velocity ${\Omega}$, given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T = -K_{T_{P}} * {\Omega}^{2}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with $K_{T_{P}}$ being an experimental constant. The effects of this torque are relatively small for small UAVs. In case of large UAVs, these effects are nullified by the same control inputs(aileron) as in other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of multi-propeller UAVs, it may be desirable to use counter-rotating propellers so that the net torque generated by the propellers as they rotate is canceled to zero. Using of contra rotating propellers is also an option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fbjwb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fbjwb.jpg&quot; alt=&quot;Quadcopter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.unmannedtech.co.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A unique case for UAVs is the quadcopter, where two propellers (rotors) spin clockwise and two spin counter-clockwise, canceling the net torque on the aircraft. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="595" LastEditDate="2015-09-14T04:30:21.987" LastActivityDate="2015-09-14T04:30:21.987" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20911" PostTypeId="1" AcceptedAnswerId="20914" CreationDate="2015-09-14T00:23:10.183" Score="3" ViewCount="5478" Body="&lt;p&gt;I mean if you rotated the propeller the other way would it result in reverse thrust.&lt;a href=&quot;https://i.stack.imgur.com/bj017.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bj017.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;I wonder this because the propeller has to rotate in a certain direction to produce thrust, but would putting it in reverse cause a force to help stop the airplane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And does this system exist with planes that have propellers?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-14T07:16:31.173" Title="If engine rotation was in reverse would it result in some kind of thrust reverser?" Tags="&lt;propeller&gt;&lt;thrust-reverser&gt;" AnswerCount="3" CommentCount="1" ClosedDate="2015-09-14T10:47:32.210" ContentLicense="CC BY-SA 3.0" />
  <row Id="20912" PostTypeId="2" ParentId="20911" CreationDate="2015-09-14T00:34:28.883" Score="4" Body="&lt;p&gt;The propeller spinning in reverse would be like flying a wing backwards... it wouldn't be efficient, and it probably wouldn't accomplish much of anything.  (Ceiling fans CAN be spun backwards to generate a breeze in the opposite direction, but they aren't exactly sophisticated airfoils!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spinning an engine backwards doesn't happen because you'd have to stop and then reverse direction of a lot of mass --- way too much momentum to reverse the direction of rotation unless you took a long time to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When props go into reverse thrust, the engine &amp;amp; propeller continue to spin in the same direction, but the angle of the blades is changed so that the thrust vector is now in the opposite direction.  That process CAN happen pretty quickly, so you have reasonably immediate reverse thrust available.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-09-14T00:34:28.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20913" PostTypeId="2" ParentId="20911" CreationDate="2015-09-14T00:34:48.533" Score="10" Body="&lt;p&gt;The propellers are like airfoils. Just as the airfoils do not produce useful lift if flown backwards, the propellers don't produce thrust if spun in opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VBYDK.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VBYDK.gif&quot; alt=&quot;Propeller thrust&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.quora.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, it is possible to obtain reverse thrust from propellers by setting a &lt;em&gt;negative pitch&lt;/em&gt;, similar to the airfoil being flown upside down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XPkzA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XPkzA.jpg&quot; alt=&quot;Propeller reverse thrust&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: 12charlie.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-14T01:07:41.100" LastActivityDate="2015-09-14T01:07:41.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20914" PostTypeId="2" ParentId="20911" CreationDate="2015-09-14T06:01:25.367" Score="7" Body="&lt;p&gt;Absolutely, but as others have said it would be a very inefficient brake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's much more effective to simply rotate (or &quot;pitch&quot;) the blades into a beta (zero-thrust -or- &quot;flat pitch&quot;) or into a negative-pitch (reverse-thrust) condition.  This is a common feature on virtually every turboprop engine and many large, powerful radial engines.  It seems to be an emerging feature for small piston aircraft, although it is still rare to see a small piston airplane with a reversing propeller.  They do exist though but they are mostly sea planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the picture that you provided, the silver dome thing from where the propeller blades sprout is the hub of the propeller.  The bases of blades &quot;plug&quot; into this hub and can rotate through a certain range dictated by a device called a &quot;governor.&quot;  The pilot can adjust a propeller control (usually part of throttle or power lever) that tells the governor to rotate the blades forwards or backwards.  During take-off, the pilot pushes the power forward which tells the engine to speed up and tells the propellers to push A LOT of air backwards for thrust.  When the pilot pulls this engine lever all the way back (on the runway during landing), he's telling the propeller blades to rotate in their sockets and push air forward instead of backwards.  Passengers hear this happen on landing as a loud roar for a few seconds as the plane slows down on the runway.  It feels like the pilot slams on the brakes but it's mostly the propeller blades reversing in their hub sockets and pushing air forward to slow the plane down.  You can also hear the pilots adjusting the propeller blade pitch to control taxi speed as you taxi around the airport but this isn't as noticeable as the landing noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's important to realize that the engine will ALWAYS spin the propeller in the same direction.  It does not stop and then spin another direction.  The only thing that changes is the &quot;pitch&quot; of the blades in their hub sockets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2015-09-14T06:01:25.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20915" PostTypeId="1" CreationDate="2015-09-14T06:39:06.833" Score="-5" ViewCount="611" Body="&lt;p&gt;I've been &lt;a href=&quot;http://www.yankee-dreamer.com/3dradar.htm&quot; rel=&quot;nofollow&quot;&gt;thinking&lt;/a&gt; about how ATC displays present information to operators and it seems that colour isn't used, at least for critical information like altitude. Since our eyes can recognize colour more quickly than they can read numbers, using colour to display altitudes seems like it would be helpful for operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any existing ATC displays use colour to encode altitude?&lt;/p&gt;&#xA;" OwnerUserId="11211" LastEditorUserId="62" LastEditDate="2015-09-16T23:01:46.467" LastActivityDate="2015-09-17T03:21:36.300" Title="Do any ATC displays use colours to indicate altitude?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;&lt;display&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20917" PostTypeId="1" AcceptedAnswerId="20941" CreationDate="2015-09-14T07:33:32.430" Score="13" ViewCount="2508" Body="&lt;p&gt;As originally designed, the DH.82 Tiger Moth had unpredictable spin characteristics. Many aircraft were lost because spin recovery took too long (i.e. too much loss of height). Many examples of the type have been retrofitted with anti-spin strakes, which extend forward along the top of the fuselage from the empennage. It's shown here on two DH.82a's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/na9hg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/na9hg.jpg&quot; alt=&quot;Two Tiger Moths, showing the anti-spin strakes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The anti-spin strakes don't prevent spinning completely, but they make the spin more manageable and more predictable. Some operators of the type nowadays haven't added the strakes, because they have found their aircraft to behave itself in the spin even unmodified. There's a theory that the unpredictability of the type was the result of variations in material and construction quality in wartime.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do the strakes help? What aerodynamic effect causes them to help spin recovery?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-09-15T22:22:21.900" Title="How do the Tiger Moth's anti-spin strakes work?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;spins&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20918" PostTypeId="2" ParentId="20915" CreationDate="2015-09-14T07:54:59.547" Score="7" Body="&lt;p&gt;That isn't a &quot;three-dimensional radar display&quot;. It is a two-dimensional display with altitude encoded as color.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current ATC radar is two-dimensional, with altitude encoded as a number:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1zaQU.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1zaQU.gif&quot; alt=&quot;ATC Target example&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A true Three-Dimensional Radar would look something like this:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4jzmr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4jzmr.jpg&quot; alt=&quot;3D Radar Tank&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Photo liberally thieved from a &lt;em&gt;1956&lt;/em&gt; edition of &lt;a href=&quot;http://www.rfcafe.com/references/popular-electronics/electronic-inventions-needed-january-1956-popular-electronics.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Popular Electronics&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as 2D radar goes, I don't believe color-coding the targets as described in the linked implementation would provide an improvement over the existing system: It's based on &quot;bands of interest&quot;, which means you need to &lt;em&gt;define what you're interested in&lt;/em&gt;, which means keystrokes - the controller is typing in what altitude they're working with to change the colors so they can see any conflicts, then they will need to change to the next altitude of interest, etc. - a lot of work versus &quot;This number is within 10 of that number. There may be a conflict if these aircraft get too close to each other.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition color-coding the targets as described forecloses other possible uses of color in the system, and doesn't eliminate the need to display the altitude (controllers still need to know the precise altitude of an aircraft to determine how far off its assigned altitude it is -- in fact &lt;em&gt;that&lt;/em&gt; may be a more apt use of color coding).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-14T07:54:59.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20919" PostTypeId="2" ParentId="20917" CreationDate="2015-09-14T08:49:57.047" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/2855-anti-spining-strake.html&quot;&gt;On this homebuilt aircraft site&lt;/a&gt; I found the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are several mechanisms available for improving controllability in a spin. One is as described above, where a triangular surface is&#xA;  placed (in a horizontal attitude) at the root of the horizontal stab.&#xA;  Practical examples of this can be seen on BD-5s and the Glastar. As&#xA;  was surmised above, for local angles of attack higher than normal, the&#xA;  strake creates a vortex which provides the airplane with additional&#xA;  stab and elevator control, helping the airplane maintain a nose low&#xA;  attitude for recovery.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A similar and more common addition is the dorsal fin - a triangular&#xA;  strake placed in front of the vertical stab. This was an effective fix&#xA;  (although not a cure) for the spin characteristics of the Grumman line&#xA;  of airplanes, which also tended to flatten out. As the plane spins,&#xA;  this strake also generates a vortex flow that is imposed onto the stab&#xA;  and rudder, thus providing a force counter to the spin direction.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The last option is rarely used but it is the addition of ventral fins&#xA;  at the aft end of the body. They serve two functions - they provide&#xA;  more aft body area thus resulting in slightly better yaw damping and&#xA;  stability and also, when in a spin they create countering lift,&#xA;  similar to that of the dorsal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;None of these are fixes - they are aids for better control and for&#xA;  providing the pilot with more control authority for getting out of an&#xA;  established spin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although it's not really an authoritive source, it sounds like a sound explanation to me. I can image that the vortex coming from the strake helps to maintain yaw authority with the rudder. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such it's an alternative to the dorsal fin, which you can still see on current aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-511795.html&quot;&gt;Here&lt;/a&gt; the user pontifex mentions from first hand experience that there's hardly any difference:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have been lucky enough to fly and teach on many training aircraft and have spun them all many, many times. I have never had any problems in recovering when using the advertised technique. Some had strakes, some didn't. Never noticed any difference. That also goes for the Chipmunk of which I have flown both versions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-09-14T08:56:03.663" LastActivityDate="2015-09-14T08:56:03.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20920" PostTypeId="1" AcceptedAnswerId="20938" CreationDate="2015-09-14T09:49:13.800" Score="25" ViewCount="7747" Body="&lt;p&gt;Based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/20899/why-isnt-the-f15e-called-f-a15&quot;&gt;this&lt;/a&gt; question, I learned that the F and A-Letters in the naming of (military) aircraft reflects what their intended purpose is.&#xA;A: Attack (Air-to-ground)&#xA;F: Fighter (Air-to-air)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;their names mostly reflect what their intended purpose is rather than their actual purpose.&lt;/p&gt;&#xA;&lt;p&gt;It is to be noted that the naming convention is followed only loosely in some cases. A good example is the F-117 Nighthawk, which is not a fighter aircraft in any sense of the word.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;from &lt;strong&gt;aeroalias&lt;/strong&gt; answer from &lt;a href=&quot;https://aviation.stackexchange.com/questions/20899/why-isnt-the-f15e-called-f-a15&quot;&gt;this&lt;/a&gt; question.&lt;/p&gt;&#xA;&lt;p&gt;The F117 isn't capable of attacking Air-Targets, it's only used as an attack aircraft. But the name of the Nighthawk is &lt;strong&gt;F&lt;/strong&gt;-117 (Fighter).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Was the idea behind the Nighthawk originally a stealth-fighter&#xA;(Air-to-Air) aircraft but was later changed to a stealth-attack&#xA;aircraft? That would explain the name '&lt;strong&gt;F&lt;/strong&gt;-117'.&lt;/li&gt;&#xA;&lt;li&gt;Are there other attack-aircraft with the &lt;strong&gt;F&lt;/strong&gt; in the name?&lt;/li&gt;&#xA;&lt;li&gt;Are there fighter-aircraft with an &lt;strong&gt;A&lt;/strong&gt; in the name?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dsTTP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dsTTP.jpg&quot; alt=&quot;F-117 Nighthawk&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-09-04T18:13:46.793" Title="Was the intended purpose of the F-117 Nighthawk originally a stealth-fighter?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;stealth&gt;&lt;aircraft-naming&gt;&lt;f-117&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20921" PostTypeId="1" CreationDate="2015-09-14T10:56:35.473" Score="3" ViewCount="1558" Body="&lt;p&gt;I am researching about ground power units for aircrafts and I need the power rating requirements (kW/kVA rating) of ground power units to supply electrical power to Bombardier Dash 8 Q400 and Embraer E145.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that aircraft need 115VAC and 28VDC, but I need the power rating of the GPU in kW or kVA like an Airbus aircraft needs a minimum of 90kVA GPU.&lt;/p&gt;&#xA;" OwnerUserId="11212" LastEditorUserId="3201" LastEditDate="2015-09-14T11:36:41.433" LastActivityDate="2016-03-07T01:33:46.653" Title="What is the power rating of the ground power unit for Bombardier Dash 8 Q400?" Tags="&lt;ground-operations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20922" PostTypeId="1" CreationDate="2015-09-14T11:13:32.057" Score="-6" ViewCount="254" Body="&lt;p&gt;I've been &lt;a href=&quot;http://www.yankee-dreamer.com/airportsensorsystem.htm&quot; rel=&quot;nofollow&quot;&gt;thinking&lt;/a&gt; about the possibility of using a buried cable to detect aircraft or other vehicles moving on the ground at an airport. The military already uses this technology for other purposes and it would avoid some issues with radio- or radar-based solutions, like ground clutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are buried-cable systems already in use for tracking surface movements at airports?  &lt;/p&gt;&#xA;" OwnerUserId="11211" LastEditorUserId="62" LastEditDate="2015-09-16T22:57:21.643" LastActivityDate="2015-09-17T05:24:17.497" Title="Do airports use buried cables to detect planes or vehicles moving?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20923" PostTypeId="1" CreationDate="2015-09-14T11:52:27.387" Score="8" ViewCount="2089" Body="&lt;p&gt;With the recent increase in laser incidents reported by pilots, why don't airliner manufacturers shield airliner cockpit glass from lasers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Abrams tank is shielded, protecting the crew from lasers. Why could a similar process not be employed in airliners?&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="878" LastEditDate="2015-09-14T11:59:33.633" LastActivityDate="2018-05-25T19:34:52.527" Title="Why are airliner cockpits not shielded from lasers?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;airliner&gt;&lt;laser-illumination&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20924" PostTypeId="1" AcceptedAnswerId="20926" CreationDate="2015-09-14T11:59:28.713" Score="3" ViewCount="2422" Body="&lt;p&gt;I get confused sometimes because I hear different theories of how propellers generate thrust.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;One is that the propeller pushes air back to provide thrust.&lt;/li&gt;&#xA;&lt;li&gt;Another is the blades generate lift creating a high pressure behind the blade pushing the aircraft forward.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is it just one of these true or is it both? For you guys its the same way of generating thrust, but to me its two ways thats my confusion. And why does a propeller need to generate lift if it just accelerates air backwards to provide thrust. That question is my main confusion. &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-09-14T21:34:09.640" LastActivityDate="2015-09-14T21:34:09.640" Title="How is thrust generated by a propeller?" Tags="&lt;propeller&gt;&lt;lift&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="0" ClosedDate="2015-09-14T21:45:26.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="20925" PostTypeId="2" ParentId="20923" CreationDate="2015-09-14T12:08:46.927" Score="8" Body="&lt;p&gt;Cynicism ensues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because it costs money, there is no regulation requiring it and airline companies probably do not feel it as being an issue because there still hasn't been a hull loss due to it (and thus do not look for it in the aircraft they buy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is said that &lt;a href=&quot;https://aviation.stackexchange.com/q/13081/1467&quot;&gt;aviation regulations are written in blood&lt;/a&gt;, so I am afraid that either we will see a hull loss somewhere, prompting EASA, FAA and similars to update the regulations, or we won't see shielded cockpits in the near future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that I refer to &quot;hull loss&quot; for a reason, there have been already &lt;a href=&quot;http://avherald.com/h?article=48189254&quot; rel=&quot;nofollow noreferrer&quot;&gt;events leading to injuries&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="7532" LastEditDate="2018-05-25T14:36:21.713" LastActivityDate="2018-05-25T14:36:21.713" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="20926" PostTypeId="2" ParentId="20924" CreationDate="2015-09-14T12:15:02.847" Score="15" Body="&lt;p&gt;It's the same thing, it changes only the point of view, see &lt;a href=&quot;https://en.wikipedia.org/wiki/Newton&amp;#39;s_laws_of_motion#Newton.27s_third_law&quot;&gt;Newton's third law&lt;/a&gt;: for each action there is an equal and opposite reaction, i.e. to create thrust, the engine has to push air backwards. Pushing the air backwards means that the air is pushing you forward and this, in the reference system of the propeller blade, is lift.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-09-14T12:15:02.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20927" PostTypeId="2" ParentId="20909" CreationDate="2015-09-14T12:41:42.927" Score="9" Body="&lt;h2&gt;In exactly the same way as any conventional, single-prop aircraft does&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Which is to say, by using stabilizer and aileron/rudder trim, and the natural resistance that wings/stabilizers give.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings/stabilizers will naturally resist rolling forces to some extent, particularly at flight speed. At lower speeds (eg when taking off or landing) the control surfaces can counter the force quite easily - a little opposite rudder and aileron is all that's required.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-09-14T12:41:42.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20928" PostTypeId="2" ParentId="20923" CreationDate="2015-09-14T13:30:20.617" Score="9" Body="&lt;p&gt;Money aside there is a bit of a practical reason as well. One of the simplest ways to protect against lasers is by filtering it using glass of a particular color, depending on the laser we are talking about red or green glass (and some other colors here and there as well). Generally they look something like this &#xA;&lt;a href=&quot;https://i.stack.imgur.com/8MRIt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8MRIt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coating an airplane windshield in glass of this tint, or a green tint would potentially impair the pilots ability to properly view PAPI or VASI lights which require red/white or red/green differentiation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vmjYo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vmjYo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also cause the pilot to perceive all lights (during a night landing) differently. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-14T13:30:20.617" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="20929" PostTypeId="2" ParentId="20922" CreationDate="2015-09-14T13:42:41.887" Score="3" Body="&lt;p&gt;Airport ground support vehicles, like the aircraft they support, are outfitted with transmitters that broadcast thier GPS position to ATC ground controllers (ADS-B). That infrastructure is already in place and implementation is ramping up rapidly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that may solve the problem you are addressing unless you are thinking of a security issue.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="340" LastEditDate="2015-09-14T13:50:25.793" LastActivityDate="2015-09-14T13:50:25.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20930" PostTypeId="2" ParentId="18747" CreationDate="2015-09-14T14:08:22.903" Score="5" Body="&lt;p&gt;They would have to work from the nose back to ensure there was no other damage but the first thing they would look at is the nose its self. As mentioned that cone is not metal as it houses the aircrafts weather radar behind it. Specifically a Honeywell unit like &lt;a href=&quot;http://www.ce560xl.com/files/Honeywell_Radar_I.pdf&quot; rel=&quot;noreferrer&quot;&gt;this one&lt;/a&gt;. By the looks of it the element was damaged and most likely needs replacing. From there you would come to the forward pressure bulkhead which, considering the damage would need to be closely inspected. Here is a pic of one from a Boeing for reference.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mWqrY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mWqrY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Degraded or improperly fixed bulkheads have lead to issues in the past. While this is happening they will also work on the windshield and check the struts around it for damage. They would also look over all forward facing surfaces, just a guess but they would check the wings leading edges for damage, engines, leading edges of the horizontal and vertical stabilizer as well as whole airframe for possible damage along its axis'. The question of will the plane ever fly again is more a question of cost than mechanical issues. For what its worth just about anything can be fixed, if and airline will fix it mainly depends on if its cheaper to fix or simply buy a new plane.      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-14T14:08:22.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20931" PostTypeId="2" ParentId="20920" CreationDate="2015-09-14T14:14:25.243" Score="18" Body="&lt;p&gt;&lt;strong&gt;a&lt;/strong&gt;. No. The F-117 Nighthawk was intended to be a stealth &lt;em&gt;attack&lt;/em&gt; aircraft from day zero. At no point was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Have_Blue&quot; rel=&quot;noreferrer&quot;&gt;Have Blue program&lt;/a&gt;,  which led to F-117, intended to produce a fighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9zwtX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9zwtX.png&quot; alt=&quot;Have Blue&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:DARPA_USAirForce_HaveBlue.png#/media/File:DARPA_USAirForce_HaveBlue.png&quot; rel=&quot;noreferrer&quot;&gt;DARPA USAirForce HaveBlue&lt;/a&gt;&quot; by &lt;a href=&quot;http://www.darpa.mil/WorkArea/DownloadAsset.aspx?id=2580&quot; rel=&quot;noreferrer&quot;&gt;US Air Force Photo&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It came to be known as the F-117 as a result of a number of unrelated reasons. The aircraft was assigned a radio call sign '117' during testing in the range of the &lt;a href=&quot;https://en.wikipedia.org/wiki/4477th_Test_and_Evaluation_Squadron&quot; rel=&quot;noreferrer&quot;&gt;Soviet aircraft being tested in US&lt;/a&gt; and the number stuck. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the 'F' in the designation appears to have been allowed by the USAF in order to confuse the Soviet intelligence. Technically, the aircraft should've had the number F-19, which was never used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;b&lt;/strong&gt;. Another very good example of an attack aircraft having the 'F' moniker is the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot; rel=&quot;noreferrer&quot;&gt;F-111 Aardvark&lt;/a&gt;, which was developed in the same time period. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bzpos.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bzpos.jpg&quot; alt=&quot;F-111&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-111F_dropping_high-drag_bombs.jpg#/media/File:F-111F_dropping_high-drag_bombs.jpg&quot; rel=&quot;noreferrer&quot;&gt;F-111F dropping high-drag bombs&lt;/a&gt;&quot; by Service Depicted: Air ForceCommand Shown: F3253Camera Operator: STAFF SGT. DAVID S. NOLAN - &lt;a href=&quot;http://www.dodmedia.osd.mil/Assets/1987/Air_Force/DF-ST-87-11197.JPEG&quot; rel=&quot;noreferrer&quot;&gt;ID:DFST8711197&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps more confusingly, after the F-111 was retired, its duties were taken up by the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15E_Strike_Eagle&quot; rel=&quot;noreferrer&quot;&gt;F-15E strike Eagle&lt;/a&gt;, among others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;c&lt;/strong&gt;. Most of the current aircraft are multirole and are capable of carrying out the strike role to varying extents. As such, they have the 'F/A' designation, like &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;noreferrer&quot;&gt;F/A-18 Hornet&lt;/a&gt; or they may have only the 'F' designation like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;noreferrer&quot;&gt;F-35 Lightning II&lt;/a&gt; in spite of the fact that it was designed to replace (among others) the A-10, an attack aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/v81ga.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/v81ga.jpg&quot; alt=&quot;F-35&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:CF-1_flight_test.jpg#/media/File:CF-1_flight_test.jpg&quot; rel=&quot;noreferrer&quot;&gt;CF-1 flight test&lt;/a&gt;&quot; by Andy Wolfe - This Image was released by the United States Navy with the ID &lt;a href=&quot;http://www.navy.mil/view_image.asp?id=97631&quot; rel=&quot;noreferrer&quot;&gt;110211-O-XX000-001&lt;/a&gt; Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-09-14T19:51:53.863" LastActivityDate="2015-09-14T19:51:53.863" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20932" PostTypeId="2" ParentId="20924" CreationDate="2015-09-14T14:20:52.787" Score="5" Body="&lt;p&gt;Both the methods you are describing are the &lt;a href=&quot;https://aviation.stackexchange.com/questions/19582/how-do-the-blades-on-a-propeller-generate-thrust?rq=1&quot;&gt;same&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The propeller pushes the air behind if you are viewing from the aircraft (or propeller).&lt;/li&gt;&#xA;&lt;li&gt;The propeller generates lift by creating a high pressure if you are in a frame of reference out of the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both are equivalent and can be used to describe what is going on.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-14T14:20:52.787" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20933" PostTypeId="1" AcceptedAnswerId="20936" CreationDate="2015-09-14T14:26:13.150" Score="20" ViewCount="1614" Body="&lt;p&gt;A &lt;a href=&quot;http://www.washingtonpost.com/news/morning-mix/wp/2015/09/13/american-airlines-accidentally-flew-the-wrong-plane-from-l-a-to-hawaii-last-month/?postshare=5661442201806293&quot; rel=&quot;nofollow&quot;&gt;recent AA flight to Hawaii&lt;/a&gt; was not &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow&quot;&gt;ETOPS rated&lt;/a&gt;.&lt;bR&gt;&#xA;(&lt;em&gt;&lt;a href=&quot;http://www.cnn.com/2015/09/13/politics/american-airlines-hawaii-airbus-a321s/&quot; rel=&quot;nofollow&quot;&gt;alternate article&lt;/a&gt;&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently the failures that led to this mistake occurred on multiple levels, including the schedulers who scheduled this equipment, and the dispatcher who may have prepped the flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is if the crew had a means and responsibility to know if the plane was ETOPS certified?   Would there be a placard for similar indicator in the cockpit stating &quot;ETOPS allowed&quot; (or perhaps &quot;No ETOPS allowed&quot;)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are parts of the checklist different for ETOPS/non-ETOPS aircraft?&#xA;Can the crew reasonably expect to fly whatever plane they're assigned without checking over every piece of the certification, maintenance, and dispatch?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="946" LastEditDate="2016-02-09T22:06:20.583" LastActivityDate="2018-01-23T09:34:38.417" Title="Are ETOPS rated planes denoted by a placard or other indicator?" Tags="&lt;safety&gt;&lt;etops&gt;&lt;dispatch&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20934" PostTypeId="2" ParentId="20920" CreationDate="2015-09-14T14:44:20.820" Score="12" Body="&lt;p&gt;The F-117 name is unusual in two ways. Not only does it use the letter F, but it continues a numbering scheme which had been abandoned long before. The &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Century_Series&quot; rel=&quot;noreferrer&quot;&gt;century series&lt;/a&gt;&quot; fighters were designed in the 1950s, and in 1962 the US introduced the &lt;a href=&quot;https://en.wikipedia.org/wiki/1962_United_States_Tri-Service_aircraft_designation_system&quot; rel=&quot;noreferrer&quot;&gt;Tri-Service aircraft designation system&lt;/a&gt;, which re-started the numbering. The first of those produced in sizable numbers was the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot; rel=&quot;noreferrer&quot;&gt;McDonnell Douglas F-4 Phantom II&lt;/a&gt;, which was initially named F-110 by the US Air Force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the fighter designation and the numbering were used as means of obfuscation. While the early work on &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Have_Blue&quot; rel=&quot;noreferrer&quot;&gt;Have Blue&lt;/a&gt; was made public, all work after 1976 was highly classified. Similar tricks were played before: The &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_163&quot; rel=&quot;noreferrer&quot;&gt;Me-163&lt;/a&gt; was initially a competing design for a call by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ministry_of_Aviation_(Nazi_Germany)&quot; rel=&quot;noreferrer&quot;&gt;RLM&lt;/a&gt; for a short-takeoff airplane which was won by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fieseler_Fi_156&quot; rel=&quot;noreferrer&quot;&gt;Fieseler 156&lt;/a&gt;. Only when design on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet&quot; rel=&quot;noreferrer&quot;&gt;rocket-powered interceptor&lt;/a&gt; started was the number re-used to divert attention away from it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-117 was intended as a strike aircraft from the outset. To be used as a fighter, any modern aircraft would need a powerful radar and external stations to carry air-to-air missiles. Both would had completely nullified the low signature of the F-117. Note that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;noreferrer&quot;&gt;F-22&lt;/a&gt; carries a special version of the &lt;a href=&quot;https://en.wikipedia.org/wiki/AIM-9_Sidewinder#AIM-9M&quot; rel=&quot;noreferrer&quot;&gt;AIM-9M Sidewinder&lt;/a&gt;, called Boxoffice, with shorter span fins to enable them to be carried internally, thus preserving the low-observable characteristics until shortly before the missile is launched.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-14T19:44:06.763" LastActivityDate="2015-09-14T19:44:06.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20935" PostTypeId="2" ParentId="20933" CreationDate="2015-09-14T15:33:59.033" Score="6" Body="&lt;p&gt;ETOPS aircraft usually will have an indication on the front nose gear doors like this picture.&lt;img src=&quot;https://i.stack.imgur.com/ZY8kZ.jpg&quot; alt=&quot;&quot;&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that an indication is given in the cockpit also on some type of aircraft info placard but I have no image to back this up. I am certain that the airlines dispatch computer system will have some sort of tag as to whether an aircraft is ETOPS rated.&lt;/p&gt;&#xA;" OwnerUserId="7373" LastEditorUserId="7373" LastEditDate="2015-09-14T15:44:16.417" LastActivityDate="2015-09-14T15:44:16.417" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20936" PostTypeId="2" ParentId="20933" CreationDate="2015-09-14T16:15:03.663" Score="12" Body="&lt;p&gt;According to FAA §25.1535 Appendix K,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane flight manual must contain the following information applicable to the ETOPS type design approval:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Required markings or placards.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) This statement: “The type-design reliability and performance of this airplane-engine combination has been evaluated under 14 CFR 25.1535 and found suitable for (identify maximum approved diversion time) extended operations (ETOPS) when the configuration, maintenance, and procedures standard contained in (identify the CMP document) are met. The actual maximum approved diversion time for this airplane may be less based on its most limiting system time capability. This finding does not constitute operational approval to conduct ETOPS.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It does not require any identification marking on the aircraft itself, though as @woakley5 noted above, a number of aircraft do have them identifying the aircraft as ETOPS certified, like below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/H4ViM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H4ViM.jpg&quot; alt=&quot;777 ETOPS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.thaiflight.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about if any indications are there in cockpit (there are no regulatory requirements, till today that is), but won't be surprised if it is available (in some aircraft, at least).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ETOPS do have some additional checks. According to Appendix G to Part 135,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(This) This ETOPS maintenance program must include the following elements:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) ETOPS pre-departure service check. The certificate holder must develop a pre-departure check tailored to their specific operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The certificate holder must complete a pre-departure service check immediately before each ETOPS flight.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) At a minimum, this check must:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Verify the condition of all ETOPS Significant Systems;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Verify the overall status of the airplane by reviewing applicable maintenance records; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Include an interior and exterior inspection to include a determination of engine and APU oil levels and consumption rates.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure how the AA Flight 31 Flight and ground crew missed these checks.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-14T16:26:41.773" LastActivityDate="2015-09-14T16:26:41.773" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20937" PostTypeId="2" ParentId="20815" CreationDate="2015-09-14T16:21:18.687" Score="4" Body="&lt;p&gt;Twelve thousand feet is a &lt;strong&gt;&lt;em&gt;really&lt;/em&gt;&lt;/strong&gt; long runway; during clear &amp;amp; dry conditions the extra four thousand feet of 16R isn't any added value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where the extra length becomes really valuable is takeoff during winter ops when the runways have enough snow on them that braking action (i.e. in the event of an aborted takeoff) is degraded, and the anti-ice systems on the aircraft are all running (reduces engine performance), and you have some really heavy aircraft.  At that point, given the high altitude at KDEN, then the extremely long runway DOES become more advantageous than the others -- especially for those heavy weight &amp;amp; performance limited aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for landings on good weather days when the airport has 6 strips of concrete (actually 5 at the moment, as 17L/35R is closed for repairs for some length of time) to choose from, you simply don't need them all.  Departing on 16R probably won't happen, because it's such a long taxi from the terminals, but departing on 34L seems fairly common... depending on where you're starting from, it's no more of a taxi than runway 8 or 25.  I've also landed (fairly recently, in fact) on 16R during good weather summer ops: arrivals from the west were getting 16R and arrivals from the east were getting 16L.  Departures were using 17R (not an ideal runway for arrivals anyway, given the taxi back north to the terminals), and the east/west runways were either being inspected or temporarily shut down so they could reverse the flow (i.e. switching from landing 26 to departing on 8, and/or landing on 7 to departing 25, or vice versa).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I've landed on 16L enough times with traffic for the parallel 16R close by, that I don't think I agree with the premise of the question.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-09-14T16:21:18.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20938" PostTypeId="2" ParentId="20920" CreationDate="2015-09-14T18:16:09.510" Score="27" Body="&lt;p&gt;The short of it is that the &quot;A&quot; designation for a ground-attack aircraft has historically been a Navy distinction. The USAF/USAAF/USAAC has not traditionally differentiated between an aircraft designed for tactical ground strikes versus a dogfighter/interceptor. Most WWII-era Air Force planes were capable of both, and would be called &quot;multirole fighters&quot; in today's parlance (including the famous P-38, P-40, P-47 and P-51). Between WWII and the adoption of the 1962 Tri-Service Aircraft Designation System, the USAF used &quot;F&quot; almost exclusively for any one- or two-man aircraft performing either the air-to-air or tactical air-to-ground role (using &quot;B&quot; for aircraft intended for larger-scale strategic bombing). Thus, the &quot;Century Series&quot; aircraft, many of which were primary ground attack aircraft, all got the &quot;Fighter&quot; designation even when their mission profile was exclusively air-to-ground, such as the F-105 and F-111.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tri-Service Aircraft Designation System was patterned most closely to the Air Force's pre-existing system, but resetting all the counters (the Navy's system involved much lower numbers, many of which were grandfathered into the new system) and adding mission designations common in the other branches, including the Navy's Attack designation. The Air Force has more or less ignored many of the finer points of this system when designating its own aircraft; the A-10, and its A-X competitor the YA-9, are the sole airframes designed primarily for the USAF to carry the Attack designation (which is fitting as both planes were designed from the ground up to kill tanks and other armor). The other A-designated aircraft to enter service with the Air Force were Navy planes first (including the A-1 Skyraider and A-7 Corsair II). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15E should, by tri-service rules, be designated AF-15E (emphasizing its modified mission of tactical strikes over its air-superiority pedigree). &quot;F/A&quot; as used for the Hornet is also non-compliant, and stems from an original desire to have separate fighter and attack variants of the Hornet which ended up being rolled into one plane. &quot;FA&quot; or &quot;AF&quot; would suffice not only for the Hornet, but also the F-16 Falcon and the F-35 Lightning II (yet another aberration, this time in the numbering, keeping the number from the X-35 tech demonstrator instead of being the F-24 as expected).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-117 is a very special case. The airframe received its designation after 1962 and so should have been designated either A-14 (as its mission has always been tactical ground strikes) or F-19 (keeping with the USAF's tendency to label any light offensive aircraft a &quot;fighter&quot;). Development of the F-117 from the Have Blue project was an open secret, and it is widely believed that the Nighthawk is the missing &quot;F-19&quot; in the U.S. numbering system (the F-20, a variant of the F-5 powered by a single larger turbofan, having been announced and demonstrated long before the F-117's existence was officially acknowledged), with the pre-1962 designation intended as misinformation.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-14T21:25:02.207" LastActivityDate="2015-09-14T21:25:02.207" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="20939" PostTypeId="2" ParentId="18747" CreationDate="2015-09-14T20:01:54.700" Score="5" Body="&lt;p&gt;All forward-facing parts need to be inspected and replaced if they show signs of damage. This includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The radome, obviously, the surrounding structure and the weather radar below it.&lt;/li&gt;&#xA;&lt;li&gt;The windshields and the surrounding structure.&lt;/li&gt;&#xA;&lt;li&gt;All leading edges and the high-lift devices attached to them. This includes all tail surfaces.&lt;/li&gt;&#xA;&lt;li&gt;The fan blades of the engines, the cowl lips and the central cone. Even though the engines look undamaged superficially, I would suspect that the fan blades have suffered multiple impacts and have developed cracks as a consequence.&lt;/li&gt;&#xA;&lt;li&gt;All instrumentation, antennas and probes which are not flush with the airframe.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To get an aircraft certified for scheduled service after this kind of damage will take several weeks if done properly. It may be flown after a thorough check and quick fixes, not for passenger service, but to transfer it to a better location to repair the damage. You probably wouldn't believe what can be made flightworthy again with the &lt;a href=&quot;http://solutions.3m.com/wps/portal/3M/en_US/Adhesives/Tapes/Products/~/Foil-Tape?N=5472880&amp;amp;rt=r3&quot; rel=&quot;noreferrer&quot;&gt;right sort of sticky tape&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-09-14T20:01:54.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20940" PostTypeId="2" ParentId="20924" CreationDate="2015-09-14T20:23:39.063" Score="1" Body="&lt;p&gt;If you imagine one of the propeller blades as a wing it can help you understand. It spins around, moving air over both sides of its blade. It is producing thrust the SAME way a wing produces lift. Airflow over the top surface, which is in front of the airplane, causes lower pressure. That negative pressure sucks the airplane forward the same way negative pressure over a wing has the effect of lifting the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thinking of it this way also helps with understanding P-factor. &lt;/p&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2015-09-14T20:23:39.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20941" PostTypeId="2" ParentId="20917" CreationDate="2015-09-14T20:37:56.470" Score="9" Body="&lt;p&gt;The vertical tail of the Tiger Moth is located a bit aft of the horizontal tail due to its sweep, such that the vertical will be in the wake of the root of the horizontal in a typical spin attitude (around 45° angle of attack). I would strongly recommend to fit the aluminium anti-spin strakes - those pilots who had no problem without them flew the Moth at a forward location of the center of gravity, which helps to end the spin. A lighter forward passenger/pilot will make the aircraft behave a lot differently; in spins &lt;a href=&quot;https://aviation.stackexchange.com/questions/1507/do-two-of-the-same-model-of-aircraft-feel-different-to-fly/13182?s=5%7C0.1764#13182&quot;&gt;small differences can translate in a markedly changed spin behavior&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UfoFh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UfoFh.png&quot; alt=&quot;de Havilland Tiger Moth cut-away drawing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cut-away drawing of the Tiger Moth's tail. The anti-spin strakes are the parts marked 16.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A spin can be ended in two ways: Either the rotation rate is stopped by neutral rudder or a rudder deflection against the spin, or the separated flow on the wing is reduced by pitching down. The first way works better for aircraft with long fuselages and low wing span, and the second is preferred in aircraft with big wings like gliders. In the end, a combination of both works best and &lt;a href=&quot;https://aviation.stackexchange.com/questions/11246/what-is-the-beggs-mueller-emergency-spin-recovery-technique?s=1%7C1.0389&quot;&gt;some aircraft need their own technique&lt;/a&gt; to end a spin safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, it helps to have as much of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin/8590?s=2%7C0.1251#8590&quot;&gt;vertical tail exposed to undisturbed airflow&lt;/a&gt; as possible. Ventral fins are a tremendous help in upright spins but useless in inverted spins. Strakes or &lt;a href=&quot;https://aviation.stackexchange.com/questions/19405/how-many-versions-of-the-p-51-dorsal-fin-fillet-are-documented&quot;&gt;fillets&lt;/a&gt; ahead of the vertical tail are very effective, especially in fast spins when the angle of sideslip at the tail is high. In the 1930s, &lt;a href=&quot;https://en.wikipedia.org/wiki/Arado_Flugzeugwerke&quot; rel=&quot;nofollow noreferrer&quot;&gt;Arado&lt;/a&gt; in Germany built a range of airplanes where the vertical tail was positioned ahead of the horizontal tail, for the express purpose of making spins easier to end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R4g9D.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R4g9D.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Arado 79 in flight (picture &lt;a href=&quot;http://www.d-eqax.de/Galerie/fullsize/Arado1_fs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The anti-spin strakes produce a vortex at high angle of attack, similar to that on a delta wing. This increases the dynamic pressure on the vertical tail and makes it more effective. Since every bit helps and the spinning characteristics can vary strongly with c.g. position, it would be careless to leave them off. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-15T22:22:21.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20942" PostTypeId="2" ParentId="20924" CreationDate="2015-09-14T20:52:42.110" Score="1" Body="&lt;p&gt;When I think of fluids and pressure gradients, I go back to Newton's first and second laws. A fluid can only accelerate in the presence of a pressure gradient, and if there is a pressure gradient then there must be acceleration (ignoring gravity for the moment). So your propeller accelerating air past it only occurs because the propeller induces a pressure gradient in the air (high pressure behind the propeller, low pressure in front), or the pressure gradient occurs because the propeller accelerates the air.  They are essentially one and the same fenomenon, either side of the equation F=MA.&lt;/p&gt;&#xA;" OwnerUserId="11218" LastActivityDate="2015-09-14T20:52:42.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20943" PostTypeId="1" AcceptedAnswerId="20949" CreationDate="2015-09-14T22:25:35.373" Score="15" ViewCount="4522" Body="&lt;p&gt;In the next picture, corresponding to a GEnx engine, what is the item circled in red?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NQmQf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NQmQf.jpg&quot; alt=&quot;Aft end of GEnx engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you very much again.&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="1696" LastEditDate="2015-09-14T22:29:27.157" LastActivityDate="2015-09-16T15:46:15.950" Title="What is this on the aft end of this GEnx engine?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20944" PostTypeId="2" ParentId="20899" CreationDate="2015-09-14T22:34:07.553" Score="7" Body="&lt;p&gt;First off, &quot;F/A&quot; is a non-standard designation under the tri-service designation system. &quot;FA&quot; or &quot;AF&quot; would be standard; the second letter would, according to the system, be the &quot;primary mission&quot; of the aircraft, whichever of those the top brass felt the design was better at. The Hornet would probably have been designated &quot;FA&quot; as its primary goal was to replace the aging A-4 Skyraider as well as to supplement the F-14.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F/A-18 has that designation because the Hornet was originally supposed to be two planes, the F-18 and the A-18, which would differ only in the required avionics and in minor differences to the weapons hardpoints. &quot;F/A-18&quot; became the internal shorthand for the project as a whole. When it was demonstrated that avionics improvements allowed a single airframe to satisfactorily perform both mission profiles, the &quot;F/A&quot; designator was applied to the production design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15E should, most accurately, be designated AF-15E, adding a &quot;modified mission&quot; designation for ground attack (similar to other modified mission designations such as the RF-4 reconnaissance variant of the Phantom, or the current EA-18G &quot;Growler&quot; variant of the Super Hornet). Its parent design was a pure air superiority fighter which was modified to produce the Strike Eagle, mainly by strengthening the wings, improving engine output, adding CFTs for better range without droptanks, and replacing practically everything under the skin forward of the intakes (avionics, radar, etc). The Strike Eagle retains much of the air superiority prowess of its lineage, and has been tasked with &quot;Combat Air Patrol&quot; missions often in addition to a primary strike mission (along the lines of &quot;go here, drop your bombs, refuel at this tanker and then stay on station for an hour before heading back&quot;), but its primary mission is ground attack (interdiction, deep strikes, SEAD, etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason why the mission designation of the Strike Eagle was not changed is that the USAF has rarely made the distinction between an air-to-air fighter and a light air-to-ground strike aircraft. Pre-1962, any one- or two-man aircraft developed for the Air Force was a &quot;fighter&quot; (evolved from the older &quot;Pursuit&quot; designation in use through WWII) regardless of its specific mission profile. After 1962 with the tri-service system in place, if the aircraft is designed with air-to-air engagements in mind, it is a &quot;fighter&quot; in the USAF's eyes no matter what else it does. The A-10 is the sole production aircraft designed for USAF use to be given that designation (which is fitting as it's designed from the ground up to kill armor, and typically carries only a pair of Sidewinder-Ms for basic self-defense); all other &quot;A&quot;-designated designs in the Air Force arsenal since 1962 have been Navy planes first, with the Air Force having to adopt the pre-existing designation under the tri-service rules. As the Navy's never really been interested in any variant of the F-15 since fairly early in the VFX program, it's only to be expected that the Air Force top brass would ignore the attack designation here.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-12-14T18:49:29.460" LastActivityDate="2015-12-14T18:49:29.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20945" PostTypeId="1" CreationDate="2015-09-14T22:34:18.843" Score="7" ViewCount="4015" Body="&lt;p&gt;When viewed from the &lt;em&gt;Z axis&lt;/em&gt; (above or below), why are modern aircraft wings often pointed as they get towards the wingtips instead of maintaining the same surface area for their entire length?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems to be a design change in the last 50-60 years, as earlier designs typically featured more rectangular wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extra points if you can explain why some rectangular wings feature rounded tips, with the maximum protrusion halfway between fore and aft of the wing.  This design was very common for biplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5nwk6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5nwk6.jpg&quot; alt=&quot;Wing narrows towards wingtip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4095" LastEditorUserId="4095" LastEditDate="2015-09-14T22:58:49.043" LastActivityDate="2015-09-17T21:33:41.587" Title="Why are modern aircraft wings often pointed instead being more rectangular?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;&lt;aircraft-structures&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20947" PostTypeId="2" ParentId="20945" CreationDate="2015-09-14T23:10:07.743" Score="1" Body="&lt;p&gt;Another reason for the &amp;quot;pointy&amp;quot; design on modern wings is the incorporation of &amp;quot;winglets&amp;quot;. Instead of ending in a stubby rectangle, the wing extends to a near point, which arcs upwards.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bcANK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bcANK.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Winglets basically reduce the drag by keeping the air smoothly running over the wing, even near the tip. It can increase fuel efficiency by around 5%, which is pretty astounding.&lt;/p&gt;&#xA;&lt;p&gt;You can read more about it here: &lt;a href=&quot;http://www.nytimes.com/2013/10/24/business/eye-catching-wingtips-but-they-arent-for-show.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.nytimes.com/2013/10/24/business/eye-catching-wingtips-but-they-arent-for-show.html&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;This paired with the general use of swept wings leads to a more &amp;quot;pointy&amp;quot; wing design that you might be referring to.&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-14T23:10:07.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20949" PostTypeId="2" ParentId="20943" CreationDate="2015-09-14T23:48:57.853" Score="20" Body="&lt;p&gt;The pipe is the center vent tube which vents air from the oil sump. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From airliners.net (User MD11Engineer):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All gas turbine engines use pressurized seals for their shaft bearing compartments to keep the oil in. The result is that the scavenge oil returning to the oil tank via the scavenge pump, chip detectors and scavenge filter contains a lot of air, it is more a foam than a liquid.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Engines use a centrifugal oil / air separator in the circuit to remove the air from the oil and to vent the system to the ambient to avoid overpressure.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;PW and RR use centrifuges attached to their main gear box, which vent overboard through a hole in the cowling.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GE and CFM use the hollow N1 shaft as a centrifuge. The heavier oil sticks to the inside of the shaft and gets returned into the circuit via holes, while the lighter air stays in the center and gets blown out through the pipe in the back.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The air blown out is not completely free of oil, so when the engine has just been shut down, you´ll see some oil vapor coming out from this pipe.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ofGds.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ofGds.png&quot; alt=&quot;Center vent&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar vent is found in other GE engines, like the GE90.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AwYsx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AwYsx.jpg&quot; alt=&quot;GE 90&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airwaysnews.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rOFxv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rOFxv.png&quot; alt=&quot;Air System Schematic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: CFM56-3 Training Manual, thanks to mins. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the actual part in GE90-100:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Tgv5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Tgv5.jpg&quot; alt=&quot;GE90-100 Central vent tube assembly&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:standardaerocomponents.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-16T15:46:15.950" LastActivityDate="2015-09-16T15:46:15.950" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20950" PostTypeId="2" ParentId="20945" CreationDate="2015-09-15T00:07:17.710" Score="2" Body="&lt;p&gt;The wings are pointed towards the wing tips because most of the aircraft flying today use swept wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The swept wing, where the wing is swept or the wing chord reduces towards the wingtip is to reduce the wave drag. This is mainly seen in the aircraft flying in transonic (civil airliners) and supersonic (combat aircraft), while rectangular wings are used in low speed general aviation aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sweeping the wing has the effect of reducing the normal velocity of the airflow as seen by the wing, by the cosine of the angle of sweep. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8DHsv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8DHsv.jpg&quot; alt=&quot;Swept wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: history.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This has the effect of increasing the critical Mach number, above which the wave drag increases significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DH5da.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DH5da.jpg&quot; alt=&quot;Wing sweep drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: history.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some rectangular wing tips are rounded off for the same reason- to reduce drag, though in this case ,they are there to reduce induce drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2tLpj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2tLpj.jpg&quot; alt=&quot;Types of Wing tips&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Sport Aviation&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the effect is marginal, so quite a few aircraft go without it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rPXIL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rPXIL.jpg&quot; alt=&quot;Comparison of wingtips&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Sport Aviation&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason for airliner wings becoming 'pointed' towards the tip is structural- The wing is practically like a cantilever beam, and reducing the cross section (of the large and long wings) towards the tip reduces the root end bending moments.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4197" LastEditDate="2015-09-15T11:18:34.220" LastActivityDate="2015-09-15T11:18:34.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20951" PostTypeId="1" AcceptedAnswerId="20955" CreationDate="2015-09-15T00:42:17.623" Score="7" ViewCount="2711" Body="&lt;p&gt;What I mean by the 7x7 series is the 707, 717, 727, etc. I took this picture at the Pima Air and Space Museum in Tucson, Arizona.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Qixr6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Qixr6m.jpg&quot; alt=&quot;Aircraft at Pima Air and Space Museum&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What type of aircraft is this? Was it an airliner? I know that no 7x7 series aircraft was that small, so were there other airliners made by Boeing besides the 7x7 series? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9IwVW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9IwVWm.jpg&quot; alt=&quot;Closeup of previous aircraft at Pima Air and Space Museum&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="39" LastEditDate="2015-09-15T04:07:13.397" LastActivityDate="2019-05-13T19:59:13.040" Title="Did Boeing build airliners other than the 7x7 series?" Tags="&lt;airliner&gt;&lt;boeing&gt;&lt;aircraft-identification&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20952" PostTypeId="2" ParentId="20951" CreationDate="2015-09-15T00:59:35.253" Score="4" Body="&lt;p&gt;All the Boeing civil &lt;em&gt;jet&lt;/em&gt; aircraft (which are the only ones under production/operation) are named in the 7x7 series. The military aircraft follow the US DoD designations, like C-17 Globemaster III, K-46 Pegasus (which is a modified 767) etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sud Aviation SE 210 Caravelle&lt;/a&gt;, produced by the French firm Sud Aviation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8o3Gu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8o3Gu.jpg&quot; alt=&quot;Sud Caravelle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Finnair_Caravelle_Basle_Airport_-_April_1976.jpg#/media/File:Finnair_Caravelle_Basle_Airport_-_April_1976.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Finnair Caravelle Basle Airport - April 1976&lt;/a&gt;&quot; by Eduard Marmet - &lt;a href=&quot;http://www.airliners.net/open.file/0101623/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airliners.net/open.file/0101623/L/&lt;/a&gt;Transferred from en.wikipedia. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was the first short/medium-range jet airliner. It first flew in 1955 and was operated till 2004, with around 282 numbers built.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-15T00:59:35.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20953" PostTypeId="2" ParentId="20951" CreationDate="2015-09-15T01:03:22.377" Score="10" Body="&lt;p&gt;To start with that picture from Pima Air and Space Museum:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a &lt;strong&gt;Sud SE-210 Caravelle VI-R&lt;/strong&gt; - the world's first medium-range jet airliner (source: Wikipedia). This particular airplane has nothing to do with Boeing. I believe it's in the Museum due to the fact that it was the world's first medium-range airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UzNpk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UzNpk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read all about it at &lt;a href=&quot;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question about whether or not Boeing had anything apart from the 700-series: it does. Not to forget the purchase of MD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A list of ALL airplanes under Boeing can be found at: &lt;a href=&quot;https://en.wikipedia.org/wiki/Category:Boeing_aircraft&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Category:Boeing_aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="-1" LastEditDate="2015-09-15T03:20:34.707" LastActivityDate="2015-09-15T03:20:34.707" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20954" PostTypeId="2" ParentId="19604" CreationDate="2015-09-15T01:04:21.333" Score="1" Body="&lt;p&gt;The F-16 has a thrust-weight ratio of greater than 1, so it is a great dogfighter, it is cheaper than an F-22 or an F-35, and it is being upgraded with faster computers and better engines. Also, the F-16CJ/DJs are the Wild Weasels right now, and when the A-10s are retired, the F-16s will make a decent CAS replacement.&lt;/p&gt;&#xA;" OwnerUserId="11222" LastActivityDate="2015-09-15T01:04:21.333" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20955" PostTypeId="2" ParentId="20951" CreationDate="2015-09-15T01:27:44.560" Score="17" Body="&lt;p&gt;&lt;strong&gt;Yes, Boeing built other airliners, with different numbering&lt;/strong&gt;, although none of them were jet-powered. Three iconic designs come to my mind right away, although there were others:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_247&quot; rel=&quot;noreferrer&quot;&gt;Boeing 247&lt;/a&gt; predated the DC-3 into service, and was a highly advanced twin-engine, monoplane cabin design. It was a pioneering aircraft, introducing all-metal construction, a cantilever wing, and retractable landing gear. It was later surpassed by the DC-3, as the 247's cabin was too small for serious airline service.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ap7Ywm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ap7Ywm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_314_Clipper&quot; rel=&quot;noreferrer&quot;&gt;Boeing 314 &quot;Clipper&quot;&lt;/a&gt; was a large four-engine flying-boat transport from just before World War II. Not quite as pioneering as the 247D, it nonetheless was massive for its time and heavily influenced later large Boeing designs.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EFesam.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EFesam.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot; rel=&quot;noreferrer&quot;&gt;Boeing 377 &quot;Stratocruiser&quot;&lt;/a&gt; was a post-World War II design based on the B-29 bomber, with a double-deck (double-bubble) fuselage and four piston engines. It was large, pressurized, and technologically advanced, but relatively unsuccessful in sales compared to contemporary designs like the Lockheed Constellation.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4dUIMm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4dUIMm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have mentioned, the aircraft in your question is a &lt;a href=&quot;http://www.airvectors.net/avcomet.html#m4&quot; rel=&quot;noreferrer&quot;&gt;Sud Caravelle&lt;/a&gt;, which was designed to solve the same problem as the later Boeing 737: it was a shorter-range airliner meant for smaller routes. You point out how much the Caravelle's nose looks like the Boeing 787, and you're right - but it is even more similar to the &lt;a href=&quot;http://www.airvectors.net/avcomet.html&quot; rel=&quot;noreferrer&quot;&gt;De Havilland Comet&lt;/a&gt;; Sud licensed the design from De Havilland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;em&gt;All photos from Wikipedia.&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-09-15T01:42:32.247" LastActivityDate="2015-09-15T01:42:32.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20956" PostTypeId="1" AcceptedAnswerId="20958" CreationDate="2015-09-15T01:51:21.607" Score="13" ViewCount="3706" Body="&lt;p&gt;During my Private Pilot's Licence days out in San Francisco, we often flew a &quot;Bay Tour&quot;: a sightseeing flight northbound from San Jose through SFO's Class B , over the city and Golden Gate Bridge, then east to Oakland and south to return to SJC. Local approach controllers were familiar with this route, and a pilot could file a flight plan for a Bay Tour with everyone knowing what he was talking about. In addition, the tower at SFO would often go out of their way to give aircraft on a Bay Tour a better view of A380's and 787's out of SFO. However, I can't find any official information on it. Is it a published procedure, or just something that everyone out there has come to know about? Do similar flight plans exist for other cities and if so, where can I find information on them?&lt;/p&gt;&#xA;" OwnerUserId="1736" LastActivityDate="2015-09-19T01:09:09.947" Title="Is the &quot;Bay Tour&quot; flight path documented, or is it a more informal route? Are there similar flight paths for other cities?" Tags="&lt;general-aviation&gt;&lt;flight-planning&gt;&lt;class-b-airspace&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20957" PostTypeId="1" CreationDate="2015-09-15T03:11:50.720" Score="6" ViewCount="383" Body="&lt;p&gt;Let's take ILS, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As stated in the FARs, the minimum RVR for a CAT I ILS approach would be 2400ft (1/2 SM) for a runway that does not have TDZ and Centerline Lighting. So, that is one limitation for such a scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple more would be the limitation to the visual references available under 91.175 of the FARs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you think of any other disadvantages if one were to conduct a precision approach on a non-precision runway?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastActivityDate="2015-09-15T04:33:06.070" Title="Conducting a Precision Approach on a Non-Precision Runway - What are my limitations?" Tags="&lt;runways&gt;&lt;approach&gt;&lt;ils&gt;&lt;far-91&gt;&lt;non-precision-approach&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20958" PostTypeId="2" ParentId="20956" CreationDate="2015-09-15T03:51:49.610" Score="11" Body="&lt;p&gt;There certainly are similar routes - the &lt;strong&gt;Niagara &lt;em&gt;Scenic Falls&lt;/em&gt; route&lt;/strong&gt;, given in FAR &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/C119237853E17565862571650050AE28?OpenDocument&quot;&gt;93.71&lt;/a&gt; comes to mind.  (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A2.0.1.3.11&quot;&gt;FAR 93 has plenty of these, by the way&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Comply with the following procedures when conducting flight over the&#xA;  area described in paragraph (a) of this section:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Fly a clockwise pattern;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Do not proceed north of the Rainbow Bridge;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Prior to joining the pattern, broadcast flight intentions on&#xA;  frequency 122.05 Mhz, giving altitude and position, and monitor the&#xA;  frequency while in the pattern;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Use the Niagara Falls airport altimeter setting. Contact Niagara&#xA;  Falls Airport Traffic Control Tower to obtain the current altimeter&#xA;  setting, to facilitate the exchange of traffic&#xA;  advisories/restrictions, and to reduce the risk of midair collisions&#xA;  between aircraft operating in the vicinity of the Falls. If the&#xA;  Control Tower is closed, use the appropriate Automatic Terminal&#xA;  Information Service (ATIS) Frequency;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Do not exceed 130 knots;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) Anticipate heavy congestion of VFR traffic at or above 3,500 feet&#xA;  MSL; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) Use caution to avoid high-speed civil and military aircraft&#xA;  transiting the area to or from Niagara Falls Airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="167" LastEditorUserId="64" LastEditDate="2015-09-15T06:21:42.217" LastActivityDate="2015-09-15T06:21:42.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20959" PostTypeId="2" ParentId="20957" CreationDate="2015-09-15T04:33:06.070" Score="4" Body="&lt;p&gt;Your limitations are exactly the same regardless of runway -- you cannot descend below the published DH without the published flight visibility minimum and the visual references required by 91.175.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the limited runway markings and lights change is the number of visual cues you have to be able to descend below MDA and land, which affects the likelihood of a successful approach in minimum weather.  Whether this is a disadvantage or not depends on the actual weather and your preparation.  If you know what lighting and markings are available (and you should), then you know what to look for.  If you are looking for lights that don't exist, you won't find them and worst case you may mis-identify other lights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only other disadvantages I can think of relate to ground movement and ILS critical area protection.  If there are no centerline lights on the runway there probably aren't lighted runway turnoff lead lines either and extra care needs to be taken when taxiing.  If the runway is located at an non-towered field and the ILS critical area has a hold short line on the taxi way, it may not be protected properly.  This is mitigated, however, by taxiway placement which probably avoids the critical area at non-towered fields (not universally true though).&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-15T04:33:06.070" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20960" PostTypeId="2" ParentId="20951" CreationDate="2015-09-15T05:44:20.153" Score="5" Body="&lt;p&gt;There was also Boeing 720, a shorter, smaller version of the Boeing 707. Wikipedia article here: &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_720&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Boeing_720&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8156" LastActivityDate="2015-09-15T05:44:20.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20963" PostTypeId="1" AcceptedAnswerId="20966" CreationDate="2015-09-15T12:35:20.270" Score="24" ViewCount="12988" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/11266/which-airliners-could-survive-an-emp-pulse#comment21207_11269&quot;&gt;this&lt;/a&gt; comment, it is postulated that even fly-by-wire aircraft (Airbus) are demonstrated to fly without any electrical systems.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All Airbus aircraft are demonstrated controllable with complete electrical failure. They would be pretty difficult to land if the electronics didn't at least partially recover (because the backup only allows controlling pitch and yaw and roll only via yaw-roll stability), but it would still be possible. [...] Jan Hudec Dec 21 '14 at 21:38 &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My question, assuming &lt;strong&gt;complete&lt;/strong&gt; electrical failure, how exactly is this done? What controls have mechanical linkage (pitch trim? engines? flaps/slats?) Would it be possible, in theory, to land the plane in such a way that some passengers could walk away? (Perfect weather, miles of flat tarmac runways everywhere, cinematic pilot capabilities)&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="21128" LastEditDate="2020-01-10T13:21:51.227" LastActivityDate="2020-01-10T13:21:51.227" Title="How are fly-by-wire airliners controlled in case of complete electrical failure?" Tags="&lt;emergency-procedures&gt;&lt;electrical-system&gt;&lt;fly-by-wire&gt;&lt;hypotheticals&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20964" PostTypeId="2" ParentId="20945" CreationDate="2015-09-15T12:44:14.513" Score="7" Body="&lt;p&gt;Rectangular wings are easy to build: You need just one rib size and can repeat making it several times, using the same jig. Early airplanes needed a lot of manual assembly by semi-skilled workers, and it made sense to simplify the task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wObue.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wObue.jpg&quot; alt=&quot;SE5a wing under construction&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SE5a wing under construction (picture &lt;a href=&quot;http://thevintageaviator.co.nz/projects/se-5a-reproduction/vintage-aviator-se-5as&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, to produce the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;least amount of induced drag&lt;/a&gt;, the downwash behind the wing should have the same angle over the whole wingspan. This can be achieved with washout, but then the washout needs to be tuned to one angle of attack. Change the angle of attack and your lift distribution over span is producing more drag than necessary. To overcome this problem, elliptic wing planforms were used, but they are complicated to build and prone to tip &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall&quot;&gt;stall&lt;/a&gt;. This is when the wing tip loses lift first during a stall and causes the aircraft to roll violently. If this happens close to the ground, a crash is inevitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, designers soon settled for something wich resembles the elliptic planform, but leaves more area at the tip such that it has less loading and more stall margin. Especially when this wing is covered with sheet metal, it makes sense to have only one direction of curvature, thus trapezoidal planforms soon became the preferred way of building wings once aluminium became the primary structural material for aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QKa0y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QKa0y.jpg&quot; alt=&quot;SB-11 side view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SB-11 glider uses a rectangular inner wing and a trapezoidal outer wing. This way, the mould for the inner wing could be used for the left and right side, making construction easier (picture &lt;a href=&quot;https://idaflieg.wordpress.com/2014/08/26/samstag-und-sonntag-23-24-08-2014-bergfest/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trapezoidal wing is also helpful in another respect: Cantilever designs have high bending moments at the wing root. If the root has more &lt;a href=&quot;https://aviation.stackexchange.com/questions/5005/what-is-the-chord-of-a-wing&quot;&gt;chord&lt;/a&gt;, the spar can be made thicker, and if the area at the tips is smaller, less bending moment is created for the same lift. The bracing of biplanes takes care of root bending moment, but when monoplanes emerged, the rectangular wing lost most of its benefits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the rounded wingtips: They are an attempt to get the wing closer to the ideal elliptic planform without losing the benefit of a constant-chord wing over most of the span. Much of the wingtip design is also about aesthetics, and some people hold quasi-religious beliefs about the benefits of a particular wing tip shape. For metal wings, wingtips can be made by pressing the aluminium sheets for the top and bottom part in shape and riveting them together since the aerodynamic loads on the wing tip are low. Wingtips and fairings were also among the first parts on aircraft to be made with composite materials, which make three-dimensional shaping much easier. Closer to the root the wing needs much more strength, and here the trapezoidal planform is still the best compromise today.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-17T21:33:41.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20965" PostTypeId="1" AcceptedAnswerId="20970" CreationDate="2015-09-15T13:31:34.570" Score="2" ViewCount="1178" Body="&lt;p&gt;The crash of the concorde resulted in many deaths, but the crash was never caused by the concorde but by a plane that took off before it. Also airliners like the Boeing 737,747,and 777 have had accidents resulting in all deaths of the passengers and crew and was caused by the airplane, but are still in service today, so why are those airplanes still in service after the accidents and the concorde not in service after its accident that wasn't even caused by the concorde?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2016-05-15T09:39:27.417" LastActivityDate="2016-05-15T09:39:27.417" Title="Why is Concorde no longer in service?" Tags="&lt;concorde&gt;" AnswerCount="3" CommentCount="1" ClosedDate="2015-09-15T14:47:52.233" ContentLicense="CC BY-SA 3.0" />
  <row Id="20966" PostTypeId="2" ParentId="20963" CreationDate="2015-09-15T13:33:44.250" Score="21" Body="&lt;p&gt;For the &lt;em&gt;complete&lt;/em&gt; electrical failure in the aircraft, the following systems have to fail:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The onboard power generation system, usually a synchronous generator has to fail in &lt;em&gt;all&lt;/em&gt; the engines.&lt;/li&gt;&#xA;&lt;li&gt;The APU (Auxiliary Power Unit) has to fail.&lt;/li&gt;&#xA;&lt;li&gt;The RAT (Ram Air Turbine) should fail to deploy.&lt;/li&gt;&#xA;&lt;li&gt;The batteries and static inverters should fail (this won't help in controlling the aircraft, just added for sake of completeness).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The probability of this happening is &lt;em&gt;very very&lt;/em&gt; low, and can be discounted. It is more probable that some other system (for e.g, hydraulics) fail before this happening. So far, to the best of my knowledge, no complete power loss has been reported in &lt;em&gt;any&lt;/em&gt; fly by wire aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason the Airbus aircrafts are controllable in case of electrical failure is due to the fact that the fly-by-wire system has multiple redundancies that offer layered protection:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Normal Law&lt;/strong&gt; offers all the protections (like stall, load factor etc). This is the system in operation during normal flights.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Alternate Law&lt;/strong&gt; offers limited protection including stability, load factor and stall protections&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Abnormal Alternate Law&lt;/strong&gt; limits the load factors and offers yaw damping only&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Direct Law&lt;/strong&gt; is the lowest level of fly-by-wire system and directly transmits the pilot inputs to control surfaces, while still giving stall and load factor warnings&lt;/li&gt;&#xA;&lt;li&gt;In case all these fail, the system reverts to &lt;em&gt;mechanical backup&lt;/em&gt;, where pitch control is achieved through the horizontal stabilizer and lateral control is accomplished using the rudder pedals. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case of mechanical backup, the system will operate as long as hydraulic power is available. In case of electrical failure, as long as hydraulics are OK, the pilot should be able to control the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, usually, if there is no power, there is no hydraulic pressure (except reservoir, maybe) and the control is lost. In case of the &lt;a href=&quot;https://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shootdown_incident&quot; rel=&quot;noreferrer&quot;&gt;Baghdad DHL aircraft&lt;/a&gt;, only hydraulics was lost and power was available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some more points to consider in case of &lt;em&gt;total&lt;/em&gt; electrical failure.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case the control surfaces are moved by electric power (like 787), power loss means loss of control.&lt;/li&gt;&#xA;&lt;li&gt;Power loss implies that the engine thrust cannot be controlled (of course, the engines won't be operational in that case anyway).&lt;/li&gt;&#xA;&lt;li&gt;Some fly-by-wire aircrafts are unstable by design. In these cases, any power loss will lead to loss of control and crash.&lt;/li&gt;&#xA;&lt;li&gt;I'm not sure there is &lt;em&gt;any&lt;/em&gt; direct mechanical linkage in civil airliners. The amount of force required to operate such a system would be enormous.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Bottom-line is, in case of &lt;em&gt;complete&lt;/em&gt; power failure, the aircraft is as good as dead. One example is a Fairchild Swearingen Metroliner (which was not fly-by-wire), that &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19880208-2&quot; rel=&quot;noreferrer&quot;&gt;lost complete electrical power&lt;/a&gt; due to a lightning strike. The aircraft entered into a uncontrolled flight, which loaded the aircraft beyond limit, resulting in its disintegration.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="753" LastEditDate="2019-08-15T11:26:58.890" LastActivityDate="2019-08-15T11:26:58.890" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="20967" PostTypeId="2" ParentId="20965" CreationDate="2015-09-15T13:46:25.000" Score="1" Body="&lt;p&gt;Mainly for three reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Increased maintenance costs.&lt;/li&gt;&#xA;&lt;li&gt;Low number of passengers after the accident of July 25, 2000.&lt;/li&gt;&#xA;&lt;li&gt;The decline in air travel following the September 11, 2001.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="11221" LastEditDate="2015-09-15T14:05:19.690" LastActivityDate="2015-09-15T14:05:19.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20968" PostTypeId="2" ParentId="20965" CreationDate="2015-09-15T13:46:36.607" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot; rel=&quot;nofollow&quot;&gt;This podcast&lt;/a&gt; covers the topic pretty closely and is a great interview with one of the old pilots of the Concorde. From his accounts the Air France Concorde crash was the last straw that lead to its shut down but was not the only factor. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde itself was, in its prime, a very profitable airplane and made BA and Air France loads of money when they flew it. However the plane was extremely costly to operate. Due to its supersonic nature the air frame saw a great deal more fatigue than a subsonic plane and it became not only expensive but time consuming to maintain the aircraft. All the while regular jets got bigger while the Concorde did not. Consider that the plane had a 100 person capacity while jumbos kept getting bigger. In turn the smaller margins jumbos made per person were beginning to catch up to that of Concorde (for what it's worth it's a pretty old plane). Much of this lead to its demise. Along with that, the down turn in air travel after 2001 lead to a big passenger slump which did not help keep the very expensive and rapidly aging plane in the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an interesting (and similar side note) check out the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_2707&quot; rel=&quot;nofollow&quot;&gt;Boeing SST&lt;/a&gt; which was a similar plane that never made it to production for similar reasons.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2015-09-15T14:10:00.400" LastActivityDate="2015-09-15T14:10:00.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20969" PostTypeId="1" AcceptedAnswerId="20980" CreationDate="2015-09-15T13:59:29.090" Score="3" ViewCount="7471" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tTz03.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tTz03.jpg&quot; alt=&quot;Left wing of 737 from the cabin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the picture above:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the parts numbered &quot;1&quot; and and &quot;3&quot;?&#xA;Is &quot;2&quot; maybe the reinforcement of the pylon?&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="4197" LastEditDate="2015-09-16T07:39:05.207" LastActivityDate="2015-09-16T07:39:05.207" Title="What are these parts on the wing of a Boeing 737?" Tags="&lt;wing&gt;&lt;boeing-737&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20970" PostTypeId="2" ParentId="20965" CreationDate="2015-09-15T14:01:00.817" Score="4" Body="&lt;p&gt;The crash was only one of the (albeit an important) reason for the grounding of Concorde. Actually, the aircraft was retired around three years after the crash. The main reason was that not enough people were flying it to keep it profitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde as a technological marvel, but it had a number of disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft was costly- The program cost over $3B and produced 20 aircraft, of which 14 were used in commercial service.&lt;/li&gt;&#xA;&lt;li&gt;Maintenance costs- The small number of aircraft and technological sophistication meant that the cost of spares was high and options limited.&lt;/li&gt;&#xA;&lt;li&gt;Operating costs- The Concorde consumed nearly three times per passenger fuel when compared to the Boeing 747-100. Still, the aircraft made operational profit due to the high cost of tickets.&lt;/li&gt;&#xA;&lt;li&gt;Recession- After 9/11 attacks exacerbated the global downturn in aviation due to recession, there was an enormous drop in first class air travel, on which Concorde was dependent on.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While announcing the retirement, British Airways cited&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;commercial reasons, with passenger revenue falling steadily against a backdrop of rising maintenance costs for the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-15T14:01:00.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20971" PostTypeId="2" ParentId="20969" CreationDate="2015-09-15T14:10:28.120" Score="6" Body="&lt;p&gt;Numbers 1 and 3 are exhaust gates to prevent damage to flaps due to engine exhaust (thanks to Peter Kämpf). Here they are in deployed condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IuB3X.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IuB3X.jpg&quot; alt=&quot;737 Exhaust Gates Deployed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: britmodeller.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Number 2 is the flap track fairing. it contains the flap operating mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same thing, from bottom:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dTuxe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dTuxe.jpg&quot; alt=&quot;Flap fairings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.b737.org.uk&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-15T22:42:58.647" LastActivityDate="2015-09-15T22:42:58.647" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="20973" PostTypeId="1" AcceptedAnswerId="20977" CreationDate="2015-09-15T15:07:24.597" Score="3" ViewCount="521" Body="&lt;p&gt;The &lt;a href=&quot;http://www.extremetech.com/extreme/170463-lockheed-unveils-sr-72-hypersonic-mach-6-scramjet-spy-plane&quot; rel=&quot;nofollow&quot;&gt;Extreme Tech website&lt;/a&gt; reports that &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Lockheed Martin’s Skunk Works has confirmed that it is developing the SR-72 spy plane. The successor to the SR-71 Blackbird, which was capable of Mach 3.5, the SR-72 will be a hypersonic unmanned aircraft capable of Mach 6, or just over 4,500 mph.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article goes on to say it will be unmanned, with the full scale vehicle built &amp;amp; tested by 2030.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not that I would &lt;strong&gt;&lt;em&gt;ever&lt;/em&gt;&lt;/strong&gt; doubt Extreme Tech or the author of this story (&lt;em&gt;cough, cough&lt;/em&gt;), but it seems odd that news of an SR-72 project isn't being far more widely reported.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any other sources reporting this new project, or is Extreme Tech the only one?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="6886" LastEditDate="2015-09-22T03:52:29.827" LastActivityDate="2015-09-22T03:52:29.827" Title="Is there an &quot;SR-72&quot; under development?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;sr-71&gt;&lt;sr-72&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20974" PostTypeId="2" ParentId="20973" CreationDate="2015-09-15T15:26:05.307" Score="0" Body="&lt;p&gt;&lt;strong&gt;Lockheed Martin is developing a lot of stuff&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's kind of the point of the skunkworks - do lots of R&amp;amp;D in lots of areas (even if you don't finish most/all projects) so that you're ready to respond quickly to whatever challenge comes up next.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, an SR-72 is pretty unlikely - who needs a high speed, stealthy recon aircraft when you have satellites?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It &lt;strong&gt;is&lt;/strong&gt; in development/under research, as a response to potential anti-satellite weapons. But it is almost certainly a top-secret, classified project....why would it be widely reported on? There will be very little information available, and any reports would likely be shut down rapidly at source if they contained much more than speculation. The project exists, we know that, but we're unlikely to get any more information, and therefore there's nothing much to say in a report&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-09-15T15:38:46.040" LastActivityDate="2015-09-15T15:38:46.040" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="20976" PostTypeId="2" ParentId="20956" CreationDate="2015-09-15T15:31:10.047" Score="5" Body="&lt;p&gt;There is not one official &quot;Bay Tour&quot; flight route. However, there are general guidelines to follow. &lt;a href=&quot;http://sjflight.com/BayTour.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;This local flight instructor's site&lt;/a&gt; explains this and offers suggestions of where you can get a map. &lt;a href=&quot;http://www.wvfc.org/request-information/newsletters/pilot-decision-making-3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is a flight briefing for one possible route&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, there are &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/productcatalog/planningcharts/VFRFlyway/&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR Flyway Planning Charts&lt;/a&gt; that you can use in certain areas of the country. &lt;a href=&quot;https://skyvector.com/?ll=37.652928397184645,-122.26654453333488&amp;amp;chart=156&amp;amp;zoom=5&quot; rel=&quot;nofollow noreferrer&quot;&gt;San Francisco has one of these&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flyway Planning Charts depict flight paths and altitudes recommended for use to by-pass areas heavily traversed by large turbine-powered aircraft. Ground references on these charts provide a guide for visual orientation. VFR Flyway Planning charts are designed for use in conjunction with TACs and are not to be used for navigation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Example section of a VFR Flyway Chart:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/imUHC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/imUHC.jpg&quot; alt=&quot;Portion of a VFR Flyway Chart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-09-15T15:36:15.117" LastActivityDate="2015-09-15T15:36:15.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20977" PostTypeId="2" ParentId="20973" CreationDate="2015-09-15T15:32:31.407" Score="6" Body="&lt;p&gt;Yes, the SR-72 project has indeed been officially announced. Lockheed &lt;a href=&quot;http://aviationweek.com/technology/skunk-works-reveals-sr-71-successor-plan&quot; rel=&quot;nofollow noreferrer&quot;&gt;confirmed it to Aviation Week&lt;/a&gt; back in 2013. Apparently it actually did get quite a bit of attention at the time, enough to actually &lt;a href=&quot;http://aviationweek.com/blog/day-spy-plane-broke-aviation-week&quot; rel=&quot;nofollow noreferrer&quot;&gt;cause Aviation Week's servers to go down for a while after the announcement.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The source quoted in the question is correct that Lockheed's announcement did confirm that the SR-72 would be hypersonic:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But now Lockheed Martin believes it has the answer. “The Skunk Works has been working with Aerojet Rocketdyne for the past seven years to develop a method to integrate an off-the-shelf turbine with a scramjet to power the aircraft from standstill to Mach 6 plus,” says Brad Leland, portfolio manager for air-breathing hypersonic technologies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, from &lt;a href=&quot;http://www.lockheedmartin.com/us/news/features/2015/sr-72.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin's own website&lt;/a&gt;, confirming both the Mach 6 capability and the intention for it having at least the option of flying unmanned:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Envisioned as an unmanned aircraft, the SR-72 would fly at speeds up to Mach 6, or six times the speed of sound.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationweek.com/technology/skunk-works-reveals-sr-71-successor-plan&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Lockheed&lt;/a&gt;, a technology demonstrator aircraft may be flying by 2018:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Lockheed has run scaled tests on components. “The next step would be to put it through a series of tests or critical demonstrations,” Leland says. “We are ready for those critical demonstrations, and we could be ready to do such a demonstration aircraft in 2018. That would be the beginning of building and running complete critical demonstrations. As of now, there are no technologies to be invented. We are ready to proceed—the only thing holding us back is the perception that [hypersonics] is always expensive, large and exotic.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here's a rendering of the proposed design from &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_SR-72&quot; rel=&quot;nofollow noreferrer&quot;&gt;the SR-72 Wikipedia page&lt;/a&gt;:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BU543.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BU543.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Lockheed_Martin_SR-72_concept.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, which apparently took it from &lt;a href=&quot;http://www.lockheedmartin.com/us/news/features/2015/sr-72.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed's website&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed was &lt;a href=&quot;https://www.fbo.gov/index?s=opportunity&amp;amp;mode=form&amp;amp;tab=core&amp;amp;id=91410a244647775c646ac3224c94395d&quot; rel=&quot;nofollow noreferrer&quot;&gt;recently awarded a grant from NASA&lt;/a&gt; to study the viability of their proposed combination turbine/ramjet engine solution for the SR-72.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Task Order No.NNC15TA03T provides for a parametric design study to establish the viability of a Turbine Based Combined Cycle (TBCC) Propulsion system consisting of integrating several combinations of near-term turbine engine solutions and a very low Mach ignition Dual Mode RamJet (DMRJ) in the SR-72 vehicle concept. Task Order NNC15TA03T is issued under Contract NNC10BA08B on a firm fixed price basis. Firm fixed price is $892,292.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-09-15T18:03:34.623" LastActivityDate="2015-09-15T18:03:34.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20978" PostTypeId="1" AcceptedAnswerId="20979" CreationDate="2015-09-15T17:12:53.627" Score="7" ViewCount="6568" Body="&lt;p&gt;Turbojet and turbofan engines have just one control lever that controls the thrust by setting the amount of fuel injected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But most turboprop aircraft have &lt;em&gt;three&lt;/em&gt; levers. One adjusts the fuel flow, one adjusts the propeller speed, but what does the third one do? Does it only act as an on-off switch as simulators tend to present it?&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-09-15T17:23:27.053" Title="What does the condition lever in turboprops control?" Tags="&lt;turboprop&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20979" PostTypeId="2" ParentId="20978" CreationDate="2015-09-15T17:21:09.613" Score="7" Body="&lt;p&gt;Shamelessly quoting from &lt;a href=&quot;http://www.skybrary.aero/index.php/Condition_Lever&quot; rel=&quot;noreferrer&quot;&gt;Skybrary&lt;/a&gt;: (emphasys mine)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Condition Lever is a pilot actuated control which is located within&#xA;  the throttle quadrant of a turboprop engine equipped aircraft. It is&#xA;  utilised to control some functions of both the propeller and the&#xA;  engine. &lt;strong&gt;These functions vary from installation to installation.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Functions of the condition lever can include any of the following: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Fuel cut-off.&lt;/li&gt;&#xA;  &lt;li&gt;Propeller feathering.&lt;/li&gt;&#xA;  &lt;li&gt;Propeller un-feathering.&lt;/li&gt;&#xA;  &lt;li&gt;Low idle/high idle selection.&lt;/li&gt;&#xA;  &lt;li&gt;Propeller speed control.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2015-09-15T17:23:27.053" LastActivityDate="2015-09-15T17:23:27.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20980" PostTypeId="2" ParentId="20969" CreationDate="2015-09-15T22:00:44.010" Score="9" Body="&lt;p&gt;I try to improve on the guesswork of @aeroalias. Here we go:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parts 1 and 3 are the two exhaust gates on either side of the aft engine fairing, which is part number 2. For a reference, see The Boeing 737 Technical Guide, page 116, by Chris Brady (&lt;a href=&quot;https://books.google.de/books?id=J6wnCQAAQBAJ&amp;amp;pg=PA116&amp;amp;lpg=PA116&amp;amp;dq=Boeing%20737%20flaps&amp;amp;source=bl&amp;amp;ots=wuFUZV47RX&amp;amp;sig=NpOF5uNX8V1OGoPBCs0NMF_9ZXo&amp;amp;hl=de&amp;amp;sa=X&amp;amp;ved=0CGMQ6AEwCDgKahUKEwjFz5-ngPrHAhVHNxQKHa_oBd8#v=onepage&amp;amp;q=Boeing%20737%20flaps&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;Google Books link&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flap &lt;a href=&quot;http://www.skytronicsinc.com/ca_product_sheets/Boeing%20737%20TEF%20Ball%20Screw%20Assembly.pdf&quot; rel=&quot;noreferrer&quot;&gt;actuation mechanism&lt;/a&gt; is quite a bit ahead of the flaps, and the same goes for the spoilers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine on the Boeing 737 is placed very close to the wing, so the flaps would sink into the jet blast when lowered to the landing position. This would cause high vibrational and thermal loads on the flaps next to the engine exhaust, especially when the pilot increases thrust in landing configuration for a go-around. To protect the flaps, the exhaust gates were added so this part of the flap does not extend down as much as the rest of the wing flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OVHOr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OVHOr.jpg&quot; alt=&quot;Boeing 737 flap detail&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drawing of the inboard wing flap of the Boeing 737-300/400/500. The inboard flap track sits within the wing root fairing, and the outer track sits in the aft engine fairing (picture &lt;a href=&quot;http://imageshack.com/f/45b737flapexhaustgateor2j&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-09-15T22:00:44.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20981" PostTypeId="1" AcceptedAnswerId="20984" CreationDate="2015-09-15T23:08:07.443" Score="3" ViewCount="1660" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zE2mY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zE2mY.jpg&quot; alt=&quot;Pilatus PC-12 parked&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Pilatus PC-12 (source: www.what2fly.com)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iXIMM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iXIMM.png&quot; alt=&quot;King Air C90 parked&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;King Air C90 (source: www.ok-aircraft.cz)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering this because of the blades on the propellers on both of the planes. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-12&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilatus PC-12&lt;/a&gt; can travel up to 360mph with its 4 blades on the propeller. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_King_Air&quot; rel=&quot;nofollow noreferrer&quot;&gt;King Air C90&lt;/a&gt; has 2 engines with 4 blades each, is around the same size and can travel at a slower speed of just 300mph. Why is this when the King Air has 2 engines instead of 1 with 4 blades and travels slower, and the Pilatus only needs one engine with 4 blades to go 360mph?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9269" LastEditDate="2017-06-14T03:08:09.227" LastActivityDate="2017-06-14T03:08:09.227" Title="Why does the Pilatus PC-12 go faster than the King Air C90?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20982" PostTypeId="1" AcceptedAnswerId="20986" CreationDate="2015-09-15T23:23:58.103" Score="1" ViewCount="272" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2kCPc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2kCPc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Piaggio_P.180_Avanti_Foxair_hl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikimedia.org&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this feature on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piaggio P.180&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe it's called a dolphin tail, but why is it exactly there and what is it for and why don't all airplanes have this?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="14897" LastEditDate="2019-02-13T20:19:36.397" LastActivityDate="2019-02-13T20:19:36.397" Title="What is this feature on a Piaggio P.180?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-09-16T04:12:54.913" ContentLicense="CC BY-SA 4.0" />
  <row Id="20983" PostTypeId="1" AcceptedAnswerId="20985" CreationDate="2015-09-16T00:25:08.800" Score="0" ViewCount="335" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nV82z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nV82z.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;I have never noticed these on any boeing planes before, so why are these on airbus a320 series and not on the boeing 737 and also what are they for?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="62" LastEditDate="2016-07-05T15:01:43.423" LastActivityDate="2016-07-05T15:01:43.423" Title="What are static discharges for on an airliner?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-09-16T01:54:19.290" ContentLicense="CC BY-SA 3.0" />
  <row Id="20984" PostTypeId="2" ParentId="20981" CreationDate="2015-09-16T00:25:13.513" Score="10" Body="&lt;p&gt;The speed of an aircraft is not only dependent on the number of propellers. It is a function of (among other things),&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Excess power available- The Pilatus PC-12 has more powerful engines compared to the King Air C90. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PT6&quot;&gt;PW PT6&lt;/a&gt; engine used in the Pilatus produces 895 kW, while (a different variant of) the same engine used in King Air produces 410 kW each. The power available for the PC-12 is more.&lt;/li&gt;&#xA;&lt;li&gt;Propeller efficiency- The PC-12 uses a different propeller compared to the C90, which may have more efficiency at high speeds. Also, the PC-12 propeller diameter is more compared to the C90.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft design- The PC-12 flew around 30 years after the C90. The aircraft design has improved in many ways during the intervening years in aerodynamics, materials etc. These improvements can be used to increase the cruise speed.&lt;/li&gt;&#xA;&lt;li&gt;Power to weight ratio- The PC-12 has a better power-to-weight ratio compared to the C90, which translates into better speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is difficult to pinpoint any single reason for increased speed. However, the increased (cruise) speed in PC-12 can be explained using a combination of the above reasons.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-09-16T14:34:58.333" LastActivityDate="2015-09-16T14:34:58.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20985" PostTypeId="2" ParentId="20983" CreationDate="2015-09-16T00:57:55.203" Score="1" Body="&lt;p&gt;It is difficult to tell by the picture, but they look like &lt;code&gt;static wicks.&lt;/code&gt; See &lt;a href=&quot;https://aviation.stackexchange.com/questions/2720/what-are-these-things-hanging-off-the-trailing-edge-of-the-wing?lq=1&quot;&gt;this&lt;/a&gt; question.&lt;/p&gt;&#xA;" OwnerUserId="3048" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-09-16T00:57:55.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="20986" PostTypeId="2" ParentId="20982" CreationDate="2015-09-16T02:24:44.413" Score="2" Body="&lt;p&gt;The airfoils shown are delta fins.  They provide lateral stability during higher speed flight.  It helps to reduce dutch rolling tendencies and to prevent deep stall characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So much so that on the Learjets I fly, there is no need for an operable yaw damper.  There is also no stick pusher or stick puller system.  Older Learjets without delta fins are required to have those two systems installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;nofollow&quot;&gt;https://en.m.wikipedia.org/wiki/Piaggio_P.180_Avanti&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2015-09-16T02:36:11.910" LastActivityDate="2015-09-16T02:36:11.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20987" PostTypeId="1" AcceptedAnswerId="20988" CreationDate="2015-09-16T02:41:58.843" Score="4" ViewCount="648" Body="&lt;p&gt;I read a book about WW2&lt;sup&gt; 1&lt;/sup&gt; and saw a couple of planes with a giant jet engine on top of them, e.g. the &lt;a href=&quot;https://en.wikipedia.org/wiki/Heinkel_He_162&quot; rel=&quot;nofollow&quot;&gt;Heinkel He 162 Salamander&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize jet engines had to have been invented before WW2 for that kind of technology to be used, so when were the first aircraft jet engines around? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sup&gt;1&lt;/sup&gt; Aircraft of World War II: 300 of the World's Greatest Aircraft. Chris Chant.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3201" LastEditDate="2015-09-16T12:00:44.747" LastActivityDate="2017-07-03T12:58:34.470" Title="When were the first jet engines used?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20988" PostTypeId="2" ParentId="20987" CreationDate="2015-09-16T03:56:02.513" Score="8" Body="&lt;p&gt;The first &lt;em&gt;aircraft&lt;/em&gt; jet engine was ground tested by Frank Whittle in April 1937. In September of the same year, Hans von Ohain (ground) tested his jet engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first jet aircraft, He 178 flew in August 1939.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-16T04:03:39.047" LastActivityDate="2015-09-16T04:03:39.047" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20989" PostTypeId="1" AcceptedAnswerId="20990" CreationDate="2015-09-16T05:44:31.403" Score="23" ViewCount="3462" Body="&lt;p&gt;I enjoy taking the time to try and visualize how fictional aircraft might actually work in reality. Unfortunately there are some that seem &lt;em&gt;highly&lt;/em&gt; impractical from an engineering student's point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One in particular is the &lt;em&gt;Bella Ciela&lt;/em&gt; from &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/The_Place_Promised_in_Our_Early_Days&quot; rel=&quot;noreferrer&quot;&gt;The Place Promised in Our Early Days&lt;/a&gt;.&quot; It features a set of blade-like wings that protrude out front and deploy into contra-rotating propellers, sustaining flight after its jet-assisted takeoff. The blades spin much slower than a conventional propeller as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gy1RS.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gy1RS.png&quot; alt=&quot;An oddball aircraft indeed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can get by the closed-loop wing. The V-tail has no issues as far as I can see. My main concern is the large rotating blades that extend far beyond the wingspan of the plane. Taking the Bella Ciela's design out of the equation and focusing on concepts alone..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QciSs.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QciSs.png&quot; alt=&quot;crude design&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How feasible is it to use a propeller larger than the wingspan? Is there any law of physics that prevent this configuration?&lt;/li&gt;&#xA;&lt;li&gt;What immediate consequences would be seen in the airflow behind such a large propeller? Would the wings aft of the flow still be able to produce stable lift?&lt;/li&gt;&#xA;&lt;li&gt;The blades remain flat when stowed and act as an additional lifting surface; but I assume one could position them so that their loss of lift doesn't affect the balance of the plane (like in the sketch, with them centered)?&lt;/li&gt;&#xA;&lt;li&gt;Without twist, can a propeller still provide efficient thrust? Could you reproduce the twist's effect by instead varying the length of the blade's chord from root to tip?&lt;/li&gt;&#xA;&lt;li&gt;Are there standard equations for calculating thrust and drag of a propeller that does not have twist? Or of a propeller in general?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can already see how drag would be a huge issue with spinning something so big. Is there a limit to how long propeller blades can get?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My apologies if I am asking [too many] questions that do not fit this board's criteria. This is just a concept that has had me Googling around for the past few hours. It's neat, and I hate dismissing things as just art without at least trying to justify them.&lt;/p&gt;&#xA;" OwnerUserId="11233" LastEditorUserId="22726" LastEditDate="2019-02-10T04:31:25.890" LastActivityDate="2019-02-10T04:31:25.890" Title="Would an aircraft with contra-rotating propellers longer than the plane's wingspan be able to fly?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;&lt;lift&gt;&lt;theory&gt;&lt;experimental-aircraft&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="20990" PostTypeId="2" ParentId="20989" CreationDate="2015-09-16T06:54:54.070" Score="38" Body="&lt;p&gt;Short answer: This design will probably work, but it will &lt;a href=&quot;https://aviation.stackexchange.com/questions/3428/do-box-wings-suffer-from-induced-drag-the-same-way-as-normal-wings/3467?s=1%7C0.2436#3467&quot;&gt;not be very efficient&lt;/a&gt;. It can be tweaked into flying, but when you start tweaking, you would continue such that the outcome would look differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's look at your questions one by one:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How feasible is it to use a propellor larger than the wingspan? Is&#xA;  there any law of physics that prevent this configuration?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no law which forbids such a large propeller. In order to create thrust, you need to accelerate a mass of air backwards. The larger the propeller, the smaller the acceleration needs to be for a given thrust, since a higher mass flow is available. This makes &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383?s=1%7C0.2221#15383&quot;&gt;large propellers inherently more efficient&lt;/a&gt;, but larger blades are heavier and also produce more friction drag, so the sweet spot is at propellers which are quite a bit smaller than the wings of the aircraft they are attached to.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What immediate consequences would be seen in the airflow behind such a&#xA;  large propellor? Would the wings aft of the flow still be able to&#xA;  produce stable lift?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the acceleration provided by the propeller to the air mass is small, the wings behind them would fly in &lt;a href=&quot;https://aviation.stackexchange.com/questions/9543/how-is-lift-provided-by-a-wing-affected-by-propeller-wake/9553?s=1%7C0.3743#9553&quot;&gt;almost undisturbed air&lt;/a&gt;. The lift will wobble a little over time, because the boundary layer flowing off the propeller blades will produce a cyclic variation in dynamic pressure on the rear wings. This will, however, not impede their general capacity to create lift.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The blades remain flat when stowed and act as an&#xA;  additional lifting surface; but I assume one could position them so&#xA;  that their loss of lift doesn't affect the balance of the plane? (Like&#xA;  the sketch with them centered)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;At slow speed it helps to have more wing area for lift creation. Note how much the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13584/why-do-airfoils-trailing-edges-point-downward/13597?s=7%7C0.1118#13597&quot;&gt;fowler flaps&lt;/a&gt; of an airliner move backwards to increase not only the wings camber, but also its area. Using two wings flying in formation would allow to give the rear wing a much higher angle of attack and to use the gap between them to refresh the rear wing's boundary layer like it is done in &lt;a href=&quot;https://aviation.stackexchange.com/questions/1128/when-boeing-designed-the-737ng-what-factors-influenced-the-change-in-the-flap-s/1168?s=2%7C0.2347#1168&quot;&gt;slotted flaps&lt;/a&gt;, so in combination their lift would be higher than that of one wing of the same area. The long, narrow propeller blades of this fictional aircraft look too flimsy, however, to be of much use in adding lift: They would break off at a fraction of their potential lift if built with existing materials.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Without twist, can a propellor still&#xA;  provide efficient thrust? Could you reproduce the twist's effect by&#xA;  instead varying the length of the blade's chord from root to tip?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Good that you added &quot;efficient&quot;; this changes the answer from a &quot;yes&quot; to a &quot;no&quot;. Only with twist would the local angle of attack be close to the optimum, but even without twist, thrust will be possible. Then the goal should be to pitch the whole propeller blade optimized for the outer 30% of its span. The thrust from this will create a strong root bending moment, however, and I doubt again that the slender prop blade will not break off. If you try to create thrust closer to the center, the outer part, which is flying at the highest dynamic pressure, will create substantial drag, requiring lots of torque, and again the propeller will break off, but in a different direction.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there standard equations for calculating thrust and drag of a&#xA;  propellor that does not have twist? Or of a propellor in general?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes. The first good ones were published by &lt;a href=&quot;http://webdoc.sub.gwdg.de/univerlag/2010/GKSM3.pdf&quot; rel=&quot;noreferrer&quot;&gt;A. Betz and L. Prandtl in 1919&lt;/a&gt;, and the latest substantial improvements were added by &lt;a href=&quot;http://de.scribd.com/doc/82049292/Minimum-Induced-Loss-Propeller-E-Larrabee&quot; rel=&quot;noreferrer&quot;&gt;Larabee&lt;/a&gt;. Incidence can be prescribed, and so can be set constant over the whole span. If you can run a copy of &lt;a href=&quot;https://aviation.stackexchange.com/questions/7651/is-there-an-equation-which-allow-us-to-perfectly-match-a-helix-propeller-and-an/7657#7657&quot;&gt;Mark Drela's XROTOR&lt;/a&gt;, you can try for yourself.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-03-13T06:34:33.603" LastActivityDate="2018-03-13T06:34:33.603" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20991" PostTypeId="1" CreationDate="2015-09-16T09:11:07.870" Score="1" ViewCount="152" Body="&lt;p&gt;On my last vacation, I took lots of photos from landing aircraft, and here are two showing the engine of two B737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/A2jw2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/A2jw2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;a href=&quot;https://i.stack.imgur.com/xpuVJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xpuVJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is that pipe on the cone of the exhaust for?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also saw them on other, larger aircraft. &#xA;Often, the exhaust looks like a large, black hole where you don't see anything inside. Maybe, those engines have such pipes, too, but you can't see them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is it's for cooling of the shaft or similar, as the exhaust gases should create a vacuum in the pipe.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2015-09-16T09:11:07.870" Title="What's that pipe at the exhaust of this engines?" Tags="&lt;jet-engine&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-09-16T09:31:24.820" ContentLicense="CC BY-SA 3.0" />
  <row Id="20993" PostTypeId="1" AcceptedAnswerId="20998" CreationDate="2015-09-16T13:03:22.177" Score="21" ViewCount="18647" Body="&lt;p&gt;Fighter jets like the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot;&gt;F-16&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle&quot;&gt;F-15&lt;/a&gt;, etc. have wings smaller than the length of the fuselage and can perform great maneuvers very quickly while an airliner with a long wingspan takes a lot of time to perform these kind of maneuvers. How does a short wingspan on a fighter jet perform such great maneuvers?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2018-04-12T14:18:58.620" LastActivityDate="2018-04-12T14:18:58.620" Title="How does a fighter jet perform good and quick maneuvers with such small wings?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;wing&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="7" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="20994" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T13:32:31.757" Score="1" Body="&lt;p&gt;Acceleration = force/mass&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighters have greater accelration (whether linear or rotational), because their force-to-mass ratio is greater than for an airliner. Simple physics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a rotational acceleration, moment of inertia takes the place of mass in the above equation. Shorter wings reduce the moment of inertia.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="849" LastEditDate="2015-09-16T18:11:46.290" LastActivityDate="2015-09-16T18:11:46.290" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="20995" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T13:59:39.153" Score="4" Body="&lt;p&gt;Fighters and aerobatic aircraft have large control surfaces (ailerons, elevators, rudders, elvons, stabilators, etc) as it is control surfaces and not the wings themselves which cause the attitude changes which maneuver the airplane. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-09-17T07:40:37.177" LastActivityDate="2015-09-17T07:40:37.177" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="20996" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T14:08:19.903" Score="9" Body="&lt;p&gt;Wingspan and maneuverability are not necessarily closely linked. Important factors that affect maneuverability are mass and thrust, which can be combined into a &lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust-to-weight_ratio&quot;&gt;thrust to weight ratio&lt;/a&gt;, and also &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot;&gt;wing loading&lt;/a&gt;, which does relate to the size of the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust to weight ratio of a 737-500 is around &lt;a href=&quot;http://www.b737.org.uk/techspecsdetailed.htm&quot;&gt;0.32&lt;/a&gt;, for an F-15 it can exceed &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle&quot;&gt;1.1&lt;/a&gt;, which is a huge difference (larger is better).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An F-15 has a nominal wing loading of 358 kg/m², compared with 497.05 for a 737-500 (lower is better).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The combined effect of increased thrust to weight ratio and reduced wing loading means a fighter jet is a very different kind of plane from a passenger liner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, regarding wing loading, on many fighter jets starting in the 1970s, the body also partly acts as part of the wing area. Notice that modern fighter fuselages do not have the cylindrical or ellipsoidal cross-sections that you see on a passenger liner. This design style further separates wingspan from maneuverability.&lt;/p&gt;&#xA;" OwnerUserId="8848" LastActivityDate="2015-09-16T14:08:19.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20997" PostTypeId="2" ParentId="20989" CreationDate="2015-09-16T14:17:23.160" Score="3" Body="&lt;p&gt;Let's talk about the propeller size for a minute and ignore the aerodynamics of the rest of the vehicle as they have been covered in another answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember that the tips of a propeller spin faster than the roots. Even though the whole propeller spins at the RPM the tips must cover more distance the roots and are thus moving faster. This can create a supersonic tip situation which can be a problem in and of itself. You can find some coverage on that in &lt;a href=&quot;https://aviation.stackexchange.com/questions/18789/can-turboprop-blades-break-the-sound-barrier/18790#18790&quot;&gt;this question&lt;/a&gt;. To keep the tips subsonic in this craft you would need to spin the propeller slowly which may not create enough thrust to fly the plane.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-09-16T17:41:07.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="20998" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T14:27:54.373" Score="34" Body="&lt;p&gt;Fighter (combat) aircraft are &lt;em&gt;designed&lt;/em&gt; to perform quick maneuvers in order to get into a position quickly to engage and shoot down an enemy aircraft or evade incoming threats (like missiles, etc.). Civil aircraft like airliners are designed with other things in mind like comfort, safety, reduced fuel consumption, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings are only a part of the story in performing maneuvers like those performed in air combat maneuvering, which depends on a number of aircraft characteristics like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Power&lt;/strong&gt; - For carrying out most of the maneuvers (like wingover), the excess power available matters. Fighter aircraft have more excess power, which translates into more acceleration. That allows it it enter into maneuvers quickly compared to the civil aircraft. In case of emergencies, the combat aircraft can use their afterburners to gain significant extra power.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Thrust-to-Weight Ratio&lt;/strong&gt; - Most of the modern fighters have high &lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust-to-weight_ratio&quot; rel=&quot;noreferrer&quot;&gt;thrust-to-weight&lt;/a&gt; ratios, usually more than 1 (which allows them to accelerate in vertical climb). This allows the fighters to accelerate far faster compared to the civil aircraft. For example, F-15 (&gt;1) had a thrust-to-weight ratio more the three times that of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; (~0.33).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2pXma.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2pXma.jpg&quot; alt=&quot;Vertical Climb&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: strategypage.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Stability&lt;/strong&gt; Most of the fighter aircraft today are designed to be unstable. This makes the aircraft respond to control inputs much more quickly compared to the airliners (which are usually not unstable in the roll axis). This means that the combat aircraft are capable of maneuvering much more quickly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Inertia&lt;/strong&gt; In case of large wings, the roll inertia is very high. This prevents them from performing quick maneuvers. Also, the damping of the large wings is also to be considered. In case of fighters, however, the short wings, having smaller inertia helps in achieving high roll rates.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Wing Loading&lt;/strong&gt; The smaller the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot; rel=&quot;noreferrer&quot;&gt;wing loading&lt;/a&gt;, the better the turn performance. Most of the combat aircraft employ a blended wing-fuselage design, that reduces the load on the wings. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt; (~300&amp;nbsp;kg/$m^{2}$) has about half the wing loading of &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;noreferrer&quot;&gt;A380&lt;/a&gt; (&gt;600&amp;nbsp;kg/$m^{2}$). In fact, an F-15 produced enough lift &lt;a href=&quot;https://en.wikipedia.org/wiki/1983_Negev_mid-air_collision&quot; rel=&quot;noreferrer&quot;&gt;with half a wing gone&lt;/a&gt; to perform a successful landing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o2Oib.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o2Oib.jpg&quot; alt=&quot;T 50 blended wing body&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:www.armchairgeneral.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Control Surfaces&lt;/strong&gt;- In general, the combat aircraft have more number of control surfaces like canards (in addition to primary control surfaces) compared to the civil aircraft. This enables the pilot to maneuver the aircraft much more quickly compared to airliners.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T1sWA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T1sWA.jpg&quot; alt=&quot;Fighter aircraft Control surfaces&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.blokeish.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to these reasons, the fighter aircraft are able to perform maneuvers much better and faster compared to airliners.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="39" LastEditDate="2015-09-16T18:01:05.430" LastActivityDate="2015-09-16T18:01:05.430" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="20999" PostTypeId="2" ParentId="5065" CreationDate="2015-09-16T15:49:57.597" Score="2" Body="&lt;p&gt;I don't believe it can be done. The area of a tandem wing isn't large enough. With solar power at 1kW per square meter that will be 15 horse power but the conversion efficiency is not 100%. It is more like 20% so you are looking at 3 horse power. A typical trike needs a minimum of a 25 horse power motor. For example the electric Icaro uses a 10kW motor and it's not even Tandem. The wing area would only be enough to provide 20% of the needed power.&lt;/p&gt;&#xA;" OwnerUserId="11237" LastActivityDate="2015-09-16T15:49:57.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21000" PostTypeId="1" AcceptedAnswerId="21003" CreationDate="2015-09-16T16:07:43.240" Score="16" ViewCount="9287" Body="&lt;p&gt;While browsing this Stack Exchange, I regularly come across mentions of &lt;em&gt;canards&lt;/em&gt;. I am not familiar with this term, and Google only gives information about ducks when I search for &quot;canard&quot;. So, what is a canard?&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="15311" LastEditDate="2017-12-07T13:53:01.170" LastActivityDate="2017-12-07T13:53:01.170" Title="What is a canard?" Tags="&lt;terminology&gt;&lt;canard&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21001" PostTypeId="2" ParentId="21000" CreationDate="2015-09-16T16:16:58.427" Score="4" Body="&lt;p&gt;The expression is shorthand for canard wing(s), small lifting surfaces mounted in front of the main wings on certain planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, many (all?) current European fighter jets have this configuration, and you may therefore occasionally see references to &quot;Euro-canards&quot; as a general group of European-developed fighter jets, such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;nofollow noreferrer&quot;&gt;SAAB Gripen&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassault Rafale&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture below shows the configuration clearly on a SAAB Gripen (&lt;a href=&quot;https://www.flickr.com/photos/stee/2748431055/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JWL7K.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JWL7K.jpg&quot; alt=&quot;SAAB Gripen with clearly visible canard wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2176" LastEditorUserId="2176" LastEditDate="2015-09-16T16:27:25.670" LastActivityDate="2015-09-16T16:27:25.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21002" PostTypeId="2" ParentId="21000" CreationDate="2015-09-16T16:20:11.140" Score="15" Body="&lt;p&gt;Your Google search has apparently had too much wine and can only speak French :)&lt;br&gt;&#xA;The relevant &lt;a href=&quot;http://dictionary.reference.com/browse/canard&quot; rel=&quot;noreferrer&quot;&gt;dictionary definition&lt;/a&gt; is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Aeronautics.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;an airplane that has its horizontal stabilizer and elevators located forward of the wing. Also called canard wing.&lt;/li&gt;&#xA;  &lt;li&gt;One of two small lifting wings located in front of the main wings.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A picture, however, is worth all of dictionary.com: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XWAgf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XWAgf.jpg&quot; alt=&quot;Eurofighter Typhoon showing canard wing&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="1563" LastEditDate="2015-09-17T08:57:37.520" LastActivityDate="2015-09-17T08:57:37.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21003" PostTypeId="2" ParentId="21000" CreationDate="2015-09-16T16:22:05.927" Score="16" Body="&lt;p&gt;In aeronautics, a canard is a small wing that is located in front of the main wing of the aircraft. This is similar to the elevator, but is located in front of the wing, instead of behind it. The configuration,and in some cases, the aircraft itself may be called a canard. From Merriam- Webster dictionary:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;an airplane with horizontal stabilizing and control surfaces in front of supporting surfaces&lt;/p&gt;&#xA;&lt;p&gt;also :  a small airfoil in front of the wing of an aircraft that can increase the aircraft's performance&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The reason why it is called a canard (French for duck) has to do with the wing location. From &lt;em&gt;Flying Magazine Jan 1982&lt;/em&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This is called a canard, from the French word for duck; with its long neck, a duck appears to have set its wing towards the rear of the fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The photo below shows the canard in front of the main wing of &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-30MKI&quot; rel=&quot;noreferrer&quot;&gt;SU 30 MKI&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rhfp0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rhfp0.jpg&quot; alt=&quot;SU 30 MKI&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source: defence.pk&lt;/p&gt;&#xA;&lt;p&gt;The canards have been used in aircraft for a long time. infact, the first aircraft, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_Flyer&quot; rel=&quot;noreferrer&quot;&gt;Wright Flyer&lt;/a&gt; was a canard biplane.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yehYW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yehYW.jpg&quot; alt=&quot;Wright Flyer&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Kitty_hawk_gross.jpg#/media/File:Kitty_hawk_gross.jpg&quot; rel=&quot;noreferrer&quot;&gt;Kitty hawk gross&lt;/a&gt;&amp;quot; by Attributed to Wilbur Wright (1867–1912) and/or Orville Wright (1871–1948). Most likely taken by Orville Wright. - &lt;a href=&quot;//commons.wikimedia.org/wiki/File:Wilbur_Wright_after_unsuccessful_flight_trial.jpg&quot; rel=&quot;noreferrer&quot; title=&quot;File:Wilbur Wright after unsuccessful flight trial.jpg&quot;&gt;File:Wilbur Wright after unsuccessful flight trial.jpg&lt;/a&gt; (itself from Library of Congress). Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The period from WWI to WWII saw the 'conventional' configuration with horizontal tail dominate the aircraft design. The canard configuration was not revived until the jet age by the European manufacturers, starting with &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_37_Viggen&quot; rel=&quot;noreferrer&quot;&gt;Saab Viggen&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R9rL8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R9rL8.jpg&quot; alt=&quot;Saab Viggen&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Saab_AJS-37_Viggen_37098_52_(SE-DXN)_(9256079273).jpg#/media/File:Saab_AJS-37_Viggen_37098_52_(SE-DXN)_(9256079273).jpg&quot; rel=&quot;noreferrer&quot;&gt;Saab AJS-37 Viggen 37098 52 (SE-DXN) (9256079273)&lt;/a&gt;&amp;quot; by Alan Wilson - Saab AJS-37 Viggen '37098/ 52' (SE-DXN)Uploaded by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:High_Contrast&quot; rel=&quot;noreferrer&quot; title=&quot;User:High Contrast&quot;&gt;High Contrast&lt;/a&gt;. Licensed under CC BY-SA 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The canard configuration is used in almost all European fighter Designs, as they have more or less exclusively turned towards tailless delta configurations.&lt;/p&gt;&#xA;&lt;p&gt;Also, a number of super-maneuverable aircraft use canards as the control authority is larger for unstable canard aircraft at high &lt;span class=&quot;math-container&quot;&gt;$C_{L}$&lt;/span&gt; than for unstable aft-tail designs. The photo below shows the canards in &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_STOL/MTD&quot; rel=&quot;noreferrer&quot;&gt;F-15 ACTIVE&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RnS00.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RnS00.jpg&quot; alt=&quot;F-15 ACTIVE&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source: tom-clancys-hawx.wikia.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-16T17:07:09.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21004" PostTypeId="2" ParentId="21000" CreationDate="2015-09-16T16:23:45.520" Score="9" Body="&lt;p&gt;A canard can mean both, the horizontal control surface placed at the forward end of an airplane and the whole airplane of this configuration itself. Also, the term canard configuration is used to distinguish it from a conventional configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term comes indeed from the French word for ducks, since they also have a relatively rear wing location when they stretch out their necks in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tksns.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tksns.jpg&quot; alt=&quot;White duck in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;White duck in flight (picture &lt;a href=&quot;https://c1.staticflickr.com/5/4016/4518477010_3411f5b80c.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airplanes built by the Wright Brothers were canards, as was the &lt;a href=&quot;https://aviation.stackexchange.com/questions/19568/why-did-the-junkers-ju-52-have-corrugated-external-surfaces/19574#19574&quot;&gt;first all-metal airplane&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LZbHq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LZbHq.jpg&quot; alt=&quot;Wright glider&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(picture &lt;a href=&quot;http://anthonymychal.com/wp-content/uploads/2012/05/north-carolina4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4Oq0u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4Oq0u.jpg&quot; alt=&quot;Reissner Ente in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reissner Ente, the first all-metal airplane, in flight (picture &lt;a href=&quot;http://alternathistory.org.ua/files/users/user675/Reissner%20Ente-02.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more modern example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gyroflug_Speed_Canard&quot; rel=&quot;nofollow noreferrer&quot;&gt;Speed Canard&lt;/a&gt;, which even uses this term in its name. Flying direction is to the right:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8UawQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8UawQ.jpg&quot; alt=&quot;Speed canard in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(picture &lt;a href=&quot;http://photos.plane-mad.com/5/large/5898.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-16T16:31:56.707" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21005" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T17:42:01.907" Score="2" Body="&lt;p&gt;Lift is proportional to wing area, not just wingspan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter jets typically have narrow wings (as you noted), but they run most of the length of the fuselage (low aspect ratio).  Larger slower-moving planes typically have long skinny wings.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Low aspect ratio wings are usually used on fighter aircraft, not only&#xA;  for the higher roll rates, but especially for longer chord and thinner&#xA;  airfoils involved in supersonic flight.&lt;br&gt;&#xA;  -- &lt;a href=&quot;https://en.wikipedia.org/wiki/Aspect_ratio_%28aeronautics%29&quot; rel=&quot;nofollow&quot;&gt;wikipedia's Aspect Ratio article&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Many jet fighters, esp. the F15 as noted in several answer, generate lift from the fuselage, significantly increasing effective wing area.  The entire wingtip-to-wingtip span is wing, because there's no non-wing fuselage in the middle.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So even though the premise of the question is somewhat flawed, there are reasons:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if fighter jets have more or less wing area per mass than larger craft.  It's reasonable to assume they have less area per nose-to-tail length, though, because mass increases with the size&lt;sup&gt;3&lt;/sup&gt;, while surface area increases with size&lt;sup&gt;2&lt;/sup&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to a big plane, 1/2 length -&gt; 1/8th mass, requiring only 1/8th wing surface area, not the 1/4 area you'd have from a proportional scale-model.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To turn, you need to get the entire mass of the plane moving in a different direction.  To pull into a loop, you not only need to change attitude quickly (large control surfaces); you also need lift from the increased angle of attack to change the plane's motion vector.  (With large control surfaces but not enough lift, you pitch up but keep moving horizontally, and stall).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Enough lift&quot; depends on the mass of the plane, because $F = m a$.  Keeping proportions the same, a larger plane would have less lift per mass, because of the cube vs square issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important factor is speed.  The faster a plane is moving, the more extra lift for you gain from pitching up.  The faster you're going, the more air you can push on per wing area.  At high speed, you don't need as much wing area to produce the max ~9G of acceleration a pilot can handle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of turning-radius, this is more than cancelled out by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Centripetal_force&quot; rel=&quot;nofollow&quot;&gt;centripetal force&lt;/a&gt; needed for a constant-radius turn increasing quadratically with speed.  (Thanks @Todd for catching this).  Degrees-per-second (angular velocity, ω) is similarly not helped by moving faster, once you're going fast enough to make a max-G-force manoeuvre.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F = lift-factor * v = ma.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$m \omega^2 r = mv^2/r = F$&lt;br&gt;&#xA;$\omega^2 r = v^2/r  = F/m = a = 9G$&lt;br&gt;&#xA;$\omega^2 = v^2 / r^2$&lt;br&gt;&#xA;$\omega = v/r$.  But for constant $a$, $r$ is proportional to $v^2$.&lt;br&gt;&#xA;$\omega = v / (v^2/a) = a/v$  (where $a$ is constant)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So at speeds fast enough for max acceleration to be the limiting factor, turn rate ~= 1/v.  At lower speeds, where achievable $a$ increases ~linearly with speed, ω is about the same at any speed up to $a = 9G$.  High thrust is needed to overcome the high drag of high lift / high angle-of-attack turning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small planes also make it easier to make wings strong enough to not snap them off at a high angle of attack (difference between heading and facing, whether it's in the vertical plane, or turning horizontally after rolling to near 90 degrees.)  Low aspect ratio wings spread the load over a longer attachment point with the fuselage, helping with this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a high angle-of-attack, the engines are contributing some of the necessary centripetal force to bend the plane's momentum vector, because they're pushing the plane in the new direction, not just along its current trajectory.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So combining all these factors, fighter jets get a lot out of their wings by moving fast, having sturdy wings that can take high loads, and by being light so the wings don't have as much mass to turn.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appropriately sized control surfaces are obviously a requirement, to hold a figher jet in a high-angle-of-attack turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think vectored thrust contributes mostly in this area.  In a (non-inverted) loop, a jet would have its thrust vectored upward, along with the elevators, pushing the tail down.  This means less thrust is contributing to centripetal force; instead it's helping to hold the plane in a higher angle of attack so the wings can pull the plane in a tighter loop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure there are some mistakes here, since I don't actually design airplanes, or even fly them outside of video games.  I'm just applying simple physics and making stuff up.  It looks like a lot of what I said is pretty much what &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot; rel=&quot;nofollow&quot;&gt;wing loading&lt;/a&gt; is.&lt;/p&gt;&#xA;" OwnerUserId="7767" LastEditorUserId="7767" LastEditDate="2015-09-16T19:46:01.253" LastActivityDate="2015-09-16T19:46:01.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21006" PostTypeId="1" CreationDate="2015-09-16T18:16:33.940" Score="8" ViewCount="2952" Body="&lt;p&gt;This &lt;a href=&quot;https://www.facebook.com/OfficialPilotsLounge/videos/764127507046469/&quot; rel=&quot;nofollow noreferrer&quot;&gt;clip&lt;/a&gt; now circulating on Facebook (&lt;a href=&quot;https://youtu.be/BjFkIgusOnY?t=3s&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube link&lt;/a&gt;) shows two pilots playing a game of Pong on the Fokker 70/100 Flight Management System (FMS). The manufacturer is presumably Honeywell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this feature really exist?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I would have hoped they had better code review to catch this, but then again I'm not sure how these work. A few veteran old employees who know ADA or whatever sitting in a dark room down the corridor when the new intern shows up?&lt;/li&gt;&#xA;&lt;li&gt;The hardware is fairly old with corresponding limitations. As much as the flight displays (EICAS) can do decent graphics, the FMC seems pretty 'paginated' and slow to react to button presses.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Update: Thanks for the input. I was fairly certain it was fake but couldn't find the error. It also provoked some interesting software debate :)&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="22726" LastEditDate="2019-03-11T03:11:19.393" LastActivityDate="2019-03-11T03:11:19.393" Title="Does the Fokker 70/100 Flight Management Computer really contain the ability to play Pong?" Tags="&lt;fms&gt;&lt;fokker-100&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21007" PostTypeId="2" ParentId="20993" CreationDate="2015-09-16T18:44:54.103" Score="3" Body="&lt;p&gt;Wingspan and maneuverability are definitely not related. Thrust to weight ratio and wing loading plays a vital role. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Traditional aircraft &lt;em&gt;maneuvering&lt;/em&gt; is accomplished by altering the flow&#xA;  of air passing over the control surfaces of the aircraft—&lt;em&gt;the ailerons,&#xA;  elevators, flaps, air brakes and rudder.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is a picture of &lt;em&gt;supermaneuverability&lt;/em&gt; of a jet fighter:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/W3Esf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/W3Esf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Supermaneuverability&quot; rel=&quot;nofollow noreferrer&quot;&gt;Supermaneuverability&lt;/a&gt;&lt;/em&gt; is the ability of aircraft to have control and do&#xA;  maneuvers in situations and in the ways exceeding that which is&#xA;  possible by pure aerodynamic mechanisms. This ability&#xA;  was first introduced in the Russian Sukhoi Su-27 and Mikoyan MiG-29&#xA;  fighter aircraft in the 1980s, which has since become a standard in&#xA;  their advanced 4th and 5th generation aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user10079" LastActivityDate="2015-09-16T18:44:54.103" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21008" PostTypeId="1" AcceptedAnswerId="21009" CreationDate="2015-09-16T22:26:18.947" Score="13" ViewCount="4294" Body="&lt;p&gt;I've found pictures and videos of jets rotating 90 degrees so that one wing points straight down to the ground and the other is straight up, then they suddenly turn away from their course while remaining in that position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=znkTGh07Mng&amp;amp;t=2m10s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here's a video of that maneuver&lt;/a&gt; (link goes to 2:10).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the aerodynamics that can make this kind of turn possible? In a lot of YouTube videos this type of turn happens after aerial refueling. Is this type of turn possible on a large airliner, and if it is, when do pilots of this airliner ever use this method in flight?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2019-04-27T16:19:48.163" LastActivityDate="2019-04-27T16:19:48.163" Title="What is this turn called and how is it performed?" Tags="&lt;airliner&gt;&lt;fighter&gt;&lt;maneuver&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="21009" PostTypeId="2" ParentId="21008" CreationDate="2015-09-16T23:13:44.423" Score="17" Body="&lt;p&gt;The maneuver is called a &quot;breakaway maneuver&quot; or simply a &quot;break&quot;, it's also sometimes colloquially referred to as &quot;peeling off&quot; in the context of aircraft leaving formation. You can see it more clearly in this video:&lt;br&gt;&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/PEfL7BgEwiY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a standard maneuver used when &lt;a href=&quot;https://www.faa.gov/news/safety_briefing/2015/media/Intercept-Procedures.pdf&quot;&gt;disengaging from a intercepted target&lt;/a&gt;, or as a way to safely exit formation flight ensuring that the departing aircraft is clear of the rest of the formation group.&lt;br&gt;&#xA;It also has tactical advantages as seen in the photo you posted (when being tracked by an infra-red/heat-seaking missile, dropping flares and a hard breakaway is one technique used to convince the missile that the flare is actually your engine, by getting your real heat source out of its &quot;line of sight&quot; quickly).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aerodynamically the breakaway maneuver is nothing more than a steep turn: Roll the aircraft into the desired bank, setting power and pitch up to maintain your altitude and airspeed in the turn as desired.&lt;br&gt;&#xA;&lt;a href=&quot;https://youtu.be/RxFvwKu9JRM&quot;&gt;A Cessna 152 flying in formation could break away using the same maneuver&lt;/a&gt;, though the bank angle and airframe loading (G forces) would need to be maintained within the aircraft's limitations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary difference with fighters and attack aircraft is that the bank angle is dramatically steeper (in the extreme, a 90-degree &quot;knife-edge&quot; bank) and the turn much tighter because these aircraft have the excess power (thrust) required to sustain flight in that configuration and are sturdy enough to withstand the G loading induced by a &quot;hard pull&quot; in the breakaway maneuver. The abrupt wings-up turn along with the nice roar you get advancing the throttles makes the maneuver an impressive one for airshow crowds to watch.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-16T23:13:44.423" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21010" PostTypeId="1" AcceptedAnswerId="21011" CreationDate="2015-09-16T23:21:50.343" Score="1" ViewCount="1214" Body="&lt;p&gt;I can never find information about the length of the horizontal stabilizer all I can find is the height of the vertical stabilizer.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-09-17T14:23:20.327" LastActivityDate="2015-09-17T14:23:20.327" Title="How long is the horizontal stabilizer on a Boeing 737?" Tags="&lt;boeing-737&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21011" PostTypeId="2" ParentId="21010" CreationDate="2015-09-16T23:31:02.307" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737sec2.pdf&quot; rel=&quot;nofollow&quot;&gt;this Boeing pdf (page 39)&lt;/a&gt;, the total length of the horizontal stabilizer on a 737-800 is 47 ft 1 in.&lt;/p&gt;&#xA;" OwnerUserId="11246" LastEditorUserId="11246" LastEditDate="2015-09-16T23:36:25.660" LastActivityDate="2015-09-16T23:36:25.660" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21012" PostTypeId="1" AcceptedAnswerId="21015" CreationDate="2015-09-17T00:30:17.567" Score="3" ViewCount="742" Body="&lt;p&gt;If they do then what aircraft are they installed in? This stabilizer is not a T-tail shaped stabilizer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0obTB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0obTB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see there are 2 v-shaped vertical stabilizers with a horizontal stabilizer hanging on the each of the vertical stabilizers. So different from a V tailed. And what advantages would this design have over a t-tail for example?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="4197" LastEditDate="2015-09-18T08:19:25.300" LastActivityDate="2015-09-18T12:47:55.513" Title="Does this type of stabilizer exist?" Tags="&lt;aircraft-design&gt;&lt;v-tail&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21013" PostTypeId="2" ParentId="20993" CreationDate="2015-09-17T01:09:44.033" Score="0" Body="&lt;p&gt;In the glider community it's been known since the early ages that a longer wingspan &lt;em&gt;decreases&lt;/em&gt; maneuverability: gliders with a larger wingspan are more &quot;lazy&quot; with the ailerons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course it is not the only factor, and as wing design has evolved into more sophisticated airfoils, the effect is less noticeable than it used to be in the past. &lt;/p&gt;&#xA;" OwnerUserId="690" LastActivityDate="2015-09-17T01:09:44.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21014" PostTypeId="2" ParentId="21006" CreationDate="2015-09-17T02:19:53.040" Score="12" Body="&lt;p&gt;The 'clip' is obviously a fake. Standards for avionics software development and testing are rigorous, with development of flight critical software being done by separate (independent) groups and legally required to be reviewed by another (independent) group.&lt;/p&gt;&#xA;&lt;p&gt;After that testing is done by another group/person who's certified by the regulatory authority. It is very very difficult and downright dangerous to have this kind of codes in flight critical system software.&lt;/p&gt;&#xA;&lt;p&gt;Also, as BowlOfRed says, there is a point in the video where the finger (of copilot?) goes behind the screen.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0N9eT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0N9eT.png&quot; alt=&quot;Screenshot&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Also, from the clip, it appears that the two 'players' predict each other's moves pretty accurately. I'm not very sure if that's the way it is played, but I doubt it.&lt;/p&gt;&#xA;&lt;p&gt;Of course, to &lt;em&gt;prove&lt;/em&gt; that something is impossible is not possible, but I'm quite certain that the clip is a fake.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-17T02:19:53.040" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21015" PostTypeId="2" ParentId="21012" CreationDate="2015-09-17T03:35:38.697" Score="8" Body="&lt;p&gt;I don't know if such a structure actually exists, but I find it difficult to see why anybody would build one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, placing the horizontal stabilisers at the top of two separate tail fins will require that each fin is strengthened to support the extra weight and the aerodynamic loads,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, there will probably be any number of aerodynamic issues around the joints between the components, each of which will be doubled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thirdly, in a real aeroplane you will have introduced substantial complexity into the control systems that have to manage all of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other issues, but I see very little benefit aerodynamically or structurally to such a layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A conventional V-tail involves some control complexity, but does away with the weight of the vertical stabiliser. A T-tail retains the vertical stabiliser, but avoids control complexity, aerodynamic issues that may occur close to the engines, and can use the extra length to improve the leverage available to the horizontal stabiliser.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that said, aircraft design is about compromise and utility. There may exist some powerful reason for adopting a sub-optimal layout to fulfil some specific purpose. You can see such an example in the design of the AN-225 Mriya which was originally built to transport the Soviet Buran spacecraft. The vertical stabilisers were moved to the ends of the horizontal stabilisers to keep the clear of the wake from the spacecraft riding piggy back. The 747 used to transport the US Space Shuttle had a similar modification, but retained the original vertical stabiliser.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Soviet Buran spacecraft during transport:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CioX3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CioX3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;US Space Shuttle &lt;em&gt;Atlantis&lt;/em&gt; during transport (&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Atlantis_on_Shuttle_Carrier_Aircraft.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;image source: Wikipedia/NASA&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B1dDD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B1dDD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11248" LastEditorUserId="753" LastEditDate="2015-09-18T11:40:51.430" LastActivityDate="2015-09-18T11:40:51.430" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21016" PostTypeId="1" AcceptedAnswerId="21018" CreationDate="2015-09-17T05:00:08.470" Score="7" ViewCount="2844" Body="&lt;p&gt;Are slats only used when there is a short runway or on all occasions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PusnI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PusnI.jpg&quot; alt=&quot;aircraft slats&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9173" LastEditorUserId="9173" LastEditDate="2015-09-17T06:03:07.280" LastActivityDate="2015-09-17T09:15:49.193" Title="How often are slats used on airliners?" Tags="&lt;airliner&gt;&lt;landing&gt;&lt;takeoff&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21017" PostTypeId="1" CreationDate="2015-09-17T06:05:12.583" Score="85" ViewCount="46860" Body="&lt;p&gt;High-end mechanical wristwatches from Swiss and German manufacturers (e.g. Breitling, Rolex etc.) are often marketed as &quot;pilot's watches&quot;, and have chronometer features to supposedly help pilots perform flight-related computations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I know next to nothing about aviation, I find it difficult to imagine that such a mechanical watch (which, for example, simply stops working if it is not moved for a few days) would be preferable to a modern quartz and/or digital watch, which keeps running for years on a single battery, self-adjusts with millisecond precision based on radio signals and even without that signal maintains time an order of magnitude more accurately than any mechanical watch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarize: What kind of watches do modern commercial pilots actually wear? Or do they nowadays just use their cellphones for timekeeping tasks like everyone else?&lt;/p&gt;&#xA;" OwnerUserId="11250" LastActivityDate="2018-05-17T13:59:52.790" Title="Do pilots really wear &quot;pilot's watches&quot;?" Tags="&lt;pilots&gt;&lt;equipment&gt;" AnswerCount="11" CommentCount="7" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21018" PostTypeId="2" ParentId="21016" CreationDate="2015-09-17T07:05:35.663" Score="9" Body="&lt;p&gt;On all occasions when flaps are deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slats are a necessity when the wing uses slotted flaps or Fowler flaps for maximum lift. Those flaps cannot reach over the whole span of the wing to leave room near the wingtips for ailerons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the flaps are extended, they increase the incidence of the wing along the flap span. This leaves the outer wing at a lower incidence, but in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/16193/how-do-wings-generate-lift/16202?s=7%7C0.0395#16202&quot;&gt;vortex field of the inner wing&lt;/a&gt;. This vortex field induces a high local angle of attack over the whole wingspan, which would produce a &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375?s=2%7C0.1485#6375&quot;&gt;local stall&lt;/a&gt; at the wingtip, where the ailerons &lt;a href=&quot;https://aviation.stackexchange.com/questions/13584/why-do-airfoils-trailing-edges-point-downward/13597#13597&quot;&gt;prevent the use of slotted flaps&lt;/a&gt;. This stall would in most cases be asymmetric: One wing tip loses lift while the other barely manages to get along with the high angle of attack. The result is a strong rolling moment which will even increase once the aircraft starts to roll, because the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620?s=1%7C0.2265#3620&quot;&gt;local angle of attack&lt;/a&gt; at the down-moving wing will increase further. At this condition, the ailerons are of little help, so the roll cannot be controlled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6HM7v.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6HM7v.png&quot; alt=&quot;Angle of attack change due to movement&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Angle of attack change due to movement (own work)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider when flaps are used most often: Close to the ground, during take-off and landing. Then imagine what happens when the airplane rolls over one wing uncontrollably. To avoid this, slats are very helpful: They give the wing an extra stall margin by shifting the stall angle up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the Airbus in your picture uses slats over the whole wing, they are strictly needed only at the outer wing. Adding them ahead of the slotted flaps will increase the maximum lift and reduce the minimum speed over what is possible with flaps alone, so full-span slats (sometimes combined with &lt;a href=&quot;https://en.wikipedia.org/wiki/Krueger_flap&quot; rel=&quot;nofollow noreferrer&quot;&gt;Krüger flaps&lt;/a&gt; on the inner part of the wing) are now standard.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-17T09:15:49.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21019" PostTypeId="1" CreationDate="2015-09-17T07:54:43.657" Score="3" ViewCount="1318" Body="&lt;p&gt;I have a major exam in school tomorrow and I still don't get how to get the turning error of an aircraft magnetic compass. For example, if given an initial heading of 120 degrees and final heading of the Northern and Southern hemisphere, how to calculate the overshoot and the level off? I know the UNOS and ONUS but still don't get the concept of it. Please help me. &lt;/p&gt;&#xA;" OwnerUserId="11252" LastEditorUserId="19" LastEditDate="2016-10-31T12:04:36.783" LastActivityDate="2016-10-31T12:04:36.783" Title="How is the the turning error of an aircraft magnetic compass calculated?" Tags="&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21020" PostTypeId="2" ParentId="21017" CreationDate="2015-09-17T08:17:59.387" Score="64" Body="&lt;p&gt;High end mechanical pilots watches are very little use in the cockpit whether you are in a commercial airplane or a cessna 152. I love watches and I've searched for years for a watch that was a) very cool looking and b) actually useful when flying and I haven't found one yet. They usually fail on b) because their analogue chronometer and/or timer functions are very hard to interpret, and cannot be read at night. The digital readouts on the analogue/digital types are often small and rarely have lights for night flying. Some have lights that will only work when in calendar mode, which is about as useful as a chocolate teapot. Often the functions are hard to use and require a fair amount of fiddling to get them to work, which is not good when you have a high workload. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial airplanes are usually so full of technology that a watch is completely redundant anyway, so for commercial pilots it's a matter of style. I'm not a commercial pilot, I fly older light aircraft with less technology, so having a watch with timer and chrono functions is handy. For this I wear a Casio G-Shock as it has a large and easily readable face, a light activated by its own button, simple to use, and very rugged. Digital kitchen timers also work very well. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-09-17T08:17:59.387" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="21021" PostTypeId="2" ParentId="21016" CreationDate="2015-09-17T08:19:36.950" Score="6" Body="&lt;p&gt;The slats are high lift devices which allow the wings to operate at higher angles of attack. In most of the aircraft, the slats are deployed automatically when the flaps are deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flaps are deployed to increase the camber of the airfoil seaction, which increases the lift coeffecient (and reduces the stall speed). However, the flaps also reduce the stall angle, so the wings stall earlier (at lesser angles of attack). Better the flaps are in increasing lift coeffecient, more this reduction in stall angle is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ASo8Z.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ASo8Z.png&quot; alt=&quot;Flap configurations&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: code7700.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During landing and takeoff, when the flaps are deployed, are the conditions when the angle of attack is high. The addition of slats increases the stall angle, so that the wing angle of attack can be high without any danger of stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ziwCy.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ziwCy.gif&quot; alt=&quot;Slat and Flap&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.recreationalflying.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this reason, the slats are used in &lt;em&gt;all&lt;/em&gt; occasions when the flaps are deployed (during takeoffs and landings). Actually, the flap/slats are controlled by the same lever so that the slats are deployed whenever the flaps are extended. For example, the Embraer 190 flap/slat control lever looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LJrZW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LJrZW.jpg&quot; alt=&quot;Flap/Slat control&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.woodward.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.embraercommercialaviation.com/Pages/Ejets-190.aspx&quot; rel=&quot;noreferrer&quot;&gt;Embraer 190&lt;/a&gt; Flight control System Summary,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Slat and flap motion is sequenced such that slats extend first and flaps retracts first when the motion command requires both surfaces to move.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-17T08:42:52.307" LastActivityDate="2015-09-17T08:42:52.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21023" PostTypeId="2" ParentId="21017" CreationDate="2015-09-17T11:25:40.210" Score="1" Body="&lt;p&gt;Many do, but not for a different reason: many (not all) pilots are very well paid but have limited possibilities (time constraints, limited vacation, location and so on) to spend the earned money. Hence the expensive watches, regardless of their merit to the actual piloting.&lt;/p&gt;&#xA;" OwnerUserId="4291" LastActivityDate="2015-09-17T11:25:40.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21024" PostTypeId="2" ParentId="21017" CreationDate="2015-09-17T11:41:13.153" Score="36" Body="&lt;p&gt;Watches in today's cockpits really aren't a tool the way they were in the past. We aren't using our wristwatch as a chronograph to manage dead reckoning the way that was required before such modern luxuries as Loran &lt;em&gt;gasp&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wristwatches are more about expressing your style. It is more about jewelry. With the exception of a 24 hour Zulu hand, and a 24 hour bezel to be able to quickly reference three timezones, they mainly just look nice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have met some pilots that actually use the E6B on their watch, but most just like how it looks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation does have a very identifiable look, which is mainly what pilots are attracted to. Everyone likes to purchase things that are related to their passion, and flying is no different. Flight watches often resemble instrumentation and bring that part of the pilot's life to their wrist wherever they go. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;edit&lt;/strong&gt;&#xA;In fact, the first wristwatch was &lt;em&gt;invented&lt;/em&gt; just for pilots. One of the first wristwatches ever made was named &quot;Santos&quot; by Louis Cartier, which was made for a famous pilot at that time who complained about having to check his pocket watch while flying. (Source: &lt;a href=&quot;http://theaviationist.com/2013/12/25/aviation-wrist-watches/&quot;&gt;http://theaviationist.com/2013/12/25/aviation-wrist-watches/&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the two things are incredibly closely identified with one another. &lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2015-09-17T11:59:19.940" LastActivityDate="2015-09-17T11:59:19.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21025" PostTypeId="2" ParentId="20963" CreationDate="2015-09-17T13:27:37.377" Score="7" Body="&lt;p&gt;Which controls have mechanical linkage differs between models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In A320 the pitch trim and rudder have mechanical linkage. There is no mechanical backup for roll control; roll control is only possible via yaw-roll coupling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, that mechanical link really means hydraulic. Without hydraulic pressure the aircraft is not controllable. However at least in A320 the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;noreferrer&quot;&gt;RAT&lt;/a&gt; drives a hydraulic pump for the blue system directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanical backup is meant for the case of total failure of the flight computers rather than complete failure of electrical power, but that is well in line with what the question on which the commend was made asked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As aerolinas already mentioned, complete electric failure is extremely unlikely with all the backups there are. But then, complete failure of all the flight computers is not much more likely and as far as I can tell never happened in practice.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-09-17T13:27:37.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21026" PostTypeId="2" ParentId="21017" CreationDate="2015-09-17T13:47:40.140" Score="41" Body="&lt;p&gt;Disclosure: I am both a watch enthusiast and a Pilot but on any note...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to your question is generally no, but that varies by personal taste as well as personal choice. There are lots of threads on the various watch forums discussing this very topic &lt;a href=&quot;http://forums.watchuseek.com/f2/what-watches-do-pilots-really-wear-799468.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://forums.watchuseek.com/f7/do-pilots-wear-pilot-watches-1366353.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.askcaptainlim.com/general-propilot-76/21-are-breitling-watches-worn-by-many-pilots.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. The consensus is basically a few things. First off pilots no longer make the kind of money the once did and swiss watches have only shot up in price since say the 70's. If you are talking about an entry level professional &lt;a href=&quot;http://www.forbes.com/sites/johngoglia/2013/07/31/what-do-entry-level-regional-pilots-and-mcdonalds-workers-have-in-common/&quot; rel=&quot;noreferrer&quot;&gt;pilot making in the very low 5 figures&lt;/a&gt; the chances they are going out and buying a $5,000+ watch is low. Now lets talk function. When you are in the cockpit a watch can be useful (provided you can read it). If your heading indicator fails you can use a watch and your turn coordinator to time your turns which can save your life in the clouds. I generally start my chronograph (omega speedmaster) when I take off, this gives me not only en route time but markers of the half hour blocks when I need to switch my tanks (on a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Aircraft-Ownership/Aircraft-Fact-Sheets/Piper-Warrior&quot; rel=&quot;noreferrer&quot;&gt;piper warrior&lt;/a&gt;). For what its worth there is a clock in the plane as well as a timer so I don't need a watch but I enjoy wearing one. When I fly &lt;a href=&quot;https://en.wikipedia.org/wiki/Dead_reckoning&quot; rel=&quot;noreferrer&quot;&gt;dead reckoning&lt;/a&gt; I carry an all mechanical &lt;a href=&quot;http://www.onthedash.com/Guide/_Stopwatches/f.60-Minute_Stopwatches/&quot; rel=&quot;noreferrer&quot;&gt;Heuer Stop watch&lt;/a&gt; to time my legs. Again these things are in the plane but I find the hand held stop watch easier to use. Some fancy aviation watches provide flight computers on the bezels like breitlings but there is no way you are reading that in the air unless its really smooth up there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KX9tM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KX9tM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;           &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The consensus around the internet and from what I have seen is that commercial pilots generally wear digital stuff or nothing at all (most casio and the like). Military fighter pilots where GShock's or what ever is issued if any thing is even issued. Some pilots may wear Rolex-GMT's or the such but that seems to be those that either really like watches or were gifted it etc. However Pan Am had a &lt;a href=&quot;http://rolexpassionreport.com/15149/the-unique-pan-am-rolex-cosmograph-daytona/&quot; rel=&quot;noreferrer&quot;&gt;long standing relationship with Rolex over the years&lt;/a&gt;. Pan Am pilots may have sported an albino GMT or a special Pan Am Daytona depending on the era. &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolex_GMT_Master_II&quot; rel=&quot;noreferrer&quot;&gt;The GMT Master was even designed in partnership with Pan Am&lt;/a&gt; and issued to long haul pilots.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note there is a group of pilots that &lt;strong&gt;&lt;em&gt;ALWAYS&lt;/em&gt;&lt;/strong&gt; wear fancy swiss watches. Since the early days of the space program Omega has been the watch maker of choice for NASA and the &lt;a href=&quot;https://www.hodinkee.com/blog/a-vintage-watch-nerds-critical-dissection-of-the-new-omega-s&quot; rel=&quot;noreferrer&quot;&gt;Speedmaster&lt;/a&gt; has been the watch of choice as seen here on Buzz Aldrin  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rolex_GMT_Master_II&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/twjQd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some even say that the Speedmaster was used to time the engine burn on apollo 13 which may have in turn saved their lives. It is also reported that Neil Armstrongs Speedmaster Broke on the apollo 11 mission. Here is a comprehensive list of where all the &lt;a href=&quot;https://www.hq.nasa.gov/alsj/omega.html&quot; rel=&quot;noreferrer&quot;&gt;watches reside now.&lt;/a&gt; The watches were worn on a NATO style velcro band that was a double wrap size so it could fit over the suits for EVA. The Speedmaster is still worn in space to this day however modern space suits have a flap covering it, making it hard to see in photos. The official Speedmasters (moon watches) are certified for maned space flight and stamped as such.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/twjQd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6EjyB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also like to expand on your statement &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...which, for example, simply stops working if it is not moved for a few days&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They do not stop working, the spring winds down and they will stop ticking however as soon as they are picked up again (and the rotor is spun if its automatic) they will start ticking again. That being said if you wear the watch every day, un like a digital that may die, a mechanical watch will tick perpetually until a component physically breaks.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a bit of a tangent, some watch makers did make flight instruments (clocks) for aircraft over the years this is where much of the inspiration for the watches comes from. Elgin made a clock that was used in a few WW2 fighters, &#xA;&lt;a href=&quot;https://www.hq.nasa.gov/alsj/omega.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2YCwN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heuer even had an &lt;a href=&quot;http://www.onthedash.com/Guide/_DashMounted/Other_Models/IFR/&quot; rel=&quot;noreferrer&quot;&gt;IFR stop watch&lt;/a&gt; &#xA;&lt;a href=&quot;https://i.stack.imgur.com/2YCwN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DS5gx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2017-03-07T13:30:26.763" LastActivityDate="2017-03-07T13:30:26.763" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21027" PostTypeId="1" AcceptedAnswerId="21032" CreationDate="2015-09-17T14:12:27.950" Score="54" ViewCount="44566" Body="&lt;p&gt;What is the advantage of the F4U Corsair's gull wing design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B7rMQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B7rMQ.jpg&quot; alt=&quot;F4U CORSAIR&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there also a disadvantage to this? The wing design just seems odd, and as far as I know it is one of the only planes to use this design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this because the technology advanced so fast, or because the wing design was flawed?&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="14897" LastEditDate="2019-08-13T10:46:02.687" LastActivityDate="2019-08-13T10:46:02.687" Title="What's the advantage of the F4U Corsair's gull wing design?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;vought-f4u-corsair&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21028" PostTypeId="2" ParentId="21027" CreationDate="2015-09-17T14:33:12.410" Score="22" Body="&lt;p&gt;It is mainly related to the folding nature of the wing and the need to accommodate the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vought_F4U_Corsair#Landing_gear_and_wings&quot; rel=&quot;noreferrer&quot;&gt;landing gear&lt;/a&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...it was difficult to make the landing gear struts long enough to provide ground clearance for the large propeller. Their solution was an inverted gull wing, which considerably shortened the required length of the main gear legs.[20]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HHTvq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HHTvq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;note how the landing gear has to be pre fold. The wing design uses the wing to add height to the gear which in turn allows for shorter struts that are easier to fit in the wing. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-17T14:33:12.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21029" PostTypeId="2" ParentId="21019" CreationDate="2015-09-17T15:06:17.113" Score="2" Body="&lt;p&gt;First of all, in real life the overshoot will depend on the bank angle, so it is not really practical to do calculations unless you are doing some kind of special, precision flying or acrobatics. Normally you just get a feel for the overshoot and compensate intuitively. Exact calculations can be useful if you are doing precise figure-8's or something like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To actually do the calculation (which is based on a shallow turn 15-degrees to 20-degrees):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Target heading:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;270 or 090 no correction necessary&lt;BR&gt;&#xA;northerly -- need to overshoot&lt;BR&gt;&#xA;southerly -- need to undershoot&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Amount of correction (as variation from East/West parallel):&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;90-degree difference (eg heading 000) -- use 30-degree correction&lt;BR&gt;&#xA;60-degree difference (eg heading 330 or 030) -- use 20-degree correction&lt;BR&gt;&#xA;30-degree difference (eg heading 300 or 060) -- use 10-degree correction&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Example 1:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are on a 110 heading and want to turn to 030. You need a 20-degree overshoot. Turn left and roll out when you reach heading 010.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Example 2:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are on a 335 heading and want to turn to 240. You need a 10-degree undershoot. Turn left and roll out when you reach heading 250.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-09-17T15:19:21.307" LastActivityDate="2015-09-17T15:19:21.307" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21030" PostTypeId="2" ParentId="21027" CreationDate="2015-09-17T15:43:56.040" Score="19" Body="&lt;p&gt;This &quot;inverted gull wing&quot; design is not flawed, it just shows that the designers arrived at a different solution in their desire to reduce drag and weight, and to make the result easy enough to build.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This wing shape is not so unusual - the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_87&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ju-87 &quot;Stuka&quot;&lt;/a&gt; (below, right) used it, and so did the &lt;a href=&quot;https://en.wikipedia.org/wiki/Klemm_Kl_35&quot; rel=&quot;nofollow noreferrer&quot;&gt;Klemm 35&lt;/a&gt; (below, left), a litte sports plane from the 1930s. In both cases the idea was to have a shorter gear with lower drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jVoPc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jVoPc.jpg&quot; alt=&quot;Klemm 35 and Ju-87&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(picture sources: &lt;a href=&quot;http://www.airventure.de/oppenheim07/op07_2/Opp07_Klemm35.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Left&lt;/a&gt; and &lt;a href=&quot;http://www.kheichhorn.de/assets/images/ju_87_03.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Right&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from the obvious benefit of a &lt;a href=&quot;http://4.bp.blogspot.com/-E3R3NiS6IUo/UC-f0Xe8SNI/AAAAAAABaSw/iPsg5xZrcJo/s1600/Ha137-bia.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;shorter landing gear&lt;/a&gt;, the angle at which the wing meets the fuselage in a low-wing configuration is increased (closer to 90°), so that interference drag should be smaller. The added complexity in manufacture, however, outweighed the benefit of lower drag in most cases. Both of my examples used fixed gears, and using an inverted gull wing on them was a trick to reduce the drag of the gear leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of carrier-borne aircraft like the F4U, the lower height of the folded wingtips allows to fit the aircraft into lower hangar decks; or the airplane can afford to have a higher wing span for a given hangar deck height.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Heinkel_He_70&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heinkel He-70&lt;/a&gt; did have a retractable gear and an inverted gull wing, and here the motivation for the inverted gull wing was reduced interference drag, but its superb aerodynamic quality was mostly due to it being the first aircraft to employ countersunk rivets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3SI6U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3SI6U.jpg&quot; alt=&quot;Heinkel He-70&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heinkel He-70 (picture &lt;a href=&quot;http://www.militaryfactory.com/aircraft/imgs/heinkel-he70-blitz_4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sum it up:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Advantages:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;shorter, lighter landing gear with less drag.&lt;/li&gt;&#xA;&lt;li&gt;Less interference drag between wing root and fuselage and between gear strut and wing&lt;/li&gt;&#xA;&lt;li&gt;In case of carrier aircraft like the F4U lower height of the folded wingtips.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Disadvantages:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;More wing area needed for the same lift, since both inner and outer wing have a sizable sideways component of lift …&lt;/li&gt;&#xA;&lt;li&gt;… which also causes more friction and inducded drag&lt;/li&gt;&#xA;&lt;li&gt;Wing construction becomes more difficult and expensive&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-09-16T20:52:58.180" LastActivityDate="2017-09-16T20:52:58.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21031" PostTypeId="2" ParentId="21017" CreationDate="2015-09-17T15:57:55.117" Score="7" Body="&lt;p&gt;Watches are extremely important for a pilot, especially small aircraft that do not have sophisticated instrument clusters. Everything is time-based and generally it is much better to trust your own watch than one built into the instrument cluster (unless it is a high-precision, calibrated clock on a large aircraft). Also, if anything happens that disrupts the aircraft functions or your visibility of the instruments, a watch is critical. For example, a fire or power failure can make a panel clock unlighted or obscured. Also, you may not be in the cockpit/flight deck and need to know what time it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key factors for a &quot;pilot's watch&quot; are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;illuminated/visible in darkness &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;large numerals, clear and highly readable&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ability to manage multiple time zones easily&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;24-hour (military/zulu) display capability&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;day of the month indicator&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;rugged and water resistant, tough crystal, good quality construction&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Currently I use a Torgoen T05101. It is a good watch, but uses phosphorescence. My next watch will use tritium illumination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been known to use an egg timer in the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-09-17T17:09:33.933" LastActivityDate="2015-09-17T17:09:33.933" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21032" PostTypeId="2" ParentId="21027" CreationDate="2015-09-17T15:59:23.403" Score="63" Body="&lt;p&gt;The wing shape in the F4U Corsair is called the inverted gull wing. The main reasons for use of this is the large propeller used in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Corsair design was in response to the US Navy RFP (Request for Proposal) in 1938, which mandated the following things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It should have maximum attainable speed&lt;/li&gt;&#xA;&lt;li&gt;The stall speed should be 70 mph&lt;/li&gt;&#xA;&lt;li&gt;Minimum range of 1000 miles&lt;/li&gt;&#xA;&lt;li&gt;Bombs should be carried under the wing (this was supposed to be dropped on aircraft formations from above, which didn't work out)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In order to achieve this, the Vought engineers used the largest available engine, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-2800_Double_Wasp&quot; rel=&quot;noreferrer&quot;&gt;Prat and Whitney R2800 Double Wasp&lt;/a&gt; radial engine (this was done as the Navy, in a change of heart, vowed to consider designs with liquid-cooled engines, in contradiction with a policy settled in 1927 that required air-cooled engines for shipboard aircraft). Also, the wing area of F4U was the largest naval aircraft of its time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During design, the oil cooler and supercharger inlets were moved to wing leading edges. In order to extract power from the engine, a large (~4m dia) propeller was chosen. This large propeller caused problems with ground clearance, which necessitated an increase in the landing gear length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Vought team overcame this by choosing an inverted gull wing, which starts out with a strong anhedral, and then curved upwards to strong dihedral, with landing gear at the lowest point in the bend. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/swGYo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/swGYo.jpg&quot; alt=&quot;F4U landing gear&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F4U-Corsair_OE-EAS_OTT_2013_04_main_landing_gear.jpg#/media/File:F4U-Corsair_OE-EAS_OTT_2013_04_main_landing_gear.jpg&quot; rel=&quot;noreferrer&quot;&gt;F4U-Corsair OE-EAS OTT 2013 04 main landing gear&lt;/a&gt;&quot; by Julian Herzog. Licensed under CC BY 4.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantages of this configuration are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Shortened landing gear&lt;/li&gt;&#xA;&lt;li&gt;Elimination of the need for wing fillets, and reducing drag as the wing and fuselage were perpendicular.&lt;/li&gt;&#xA;&lt;li&gt;Simplified wing folding (the wings were folded at the lowest point), with the folded wings nearly at the height of the propellers. This enabled simple automatic mechanism for folding/unfolding, unlike the F6F Sto-wing which was manual, as the hydraulic mechanism added too much weight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bm29T.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bm29T.jpg&quot; alt=&quot;F4U folded wing&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.airport-data.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantages were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The design added weight compared to straight wing.&lt;/li&gt;&#xA;&lt;li&gt;(To some people) It was ugly&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This design has been used in a number of other aircraft too, mostly to reduce the length of the landing gear and carry large external stores, the most famous being the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_87&quot; rel=&quot;noreferrer&quot;&gt;Junkers Ju-87 Stuka&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lllOV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lllOV.jpg&quot; alt=&quot;Ju 87 Stuka&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Bundesarchiv_Bild_101I-646-5184-26,_Russland,_Flugzeug_Junkers_Ju_87_edit_1.jpg#/media/File:Bundesarchiv_Bild_101I-646-5184-26,_Russland,_Flugzeug_Junkers_Ju_87_edit_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Bundesarchiv Bild 101I-646-5184-26, Russland, Flugzeug Junkers Ju 87 edit 1&lt;/a&gt;&quot;. Licensed under CC BY-SA 3.0 de via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inverted gull wings were also used in &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairey_Gannet&quot; rel=&quot;noreferrer&quot;&gt;Fairey Gannet&lt;/a&gt;, an ASW aircraft of Royal Navy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4SyyC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4SyyC.jpg&quot; alt=&quot;Fairey Gannet&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: www.maritimequest.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was also used in some twin engined aircraft like the Caproni Ca.331.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Hoxhf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hoxhf.jpg&quot; alt=&quot;Ca 331&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: flickr.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in some books, this design is called the gull wing instead of inverted gull wing.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2015-09-17T16:45:09.520" LastActivityDate="2015-09-17T16:45:09.520" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21033" PostTypeId="2" ParentId="16659" CreationDate="2015-09-17T18:34:14.947" Score="-1" Body="&lt;p&gt;They send you up in a small airplane and turn off the engine. Just kidding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no formal training, except in the use of standard emergency equipment such as evacuation slides and the emergency oxygen system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every aircraft has an elaborately detailed set of emergency procedures which are kept in binders (although this is shifting to iPads). When something bad happens, you are supposed to turn to the relevant section of the binder (there are quick reference tabs) and follow the instructions. In theory, you are supposed to memorize all the procedures, but in practice most pilots just know the critical ones, like fires and engine failures. Even if you think you have the procedure memorized, you are still supposed to use the checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One problem with simulating emergencies is that it is dangerous. For example, the FAA used to mandate spin training for all pilots. Then, years later, they found out more people were getting killed in the spin training, than were getting killed in real, actual spins. That put an end to the spin training.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-09-17T18:34:14.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21035" PostTypeId="1" AcceptedAnswerId="21041" CreationDate="2015-09-17T19:05:48.977" Score="17" ViewCount="6703" Body="&lt;p&gt;What is the stall angle in an inverted flight configuration? How does it relate to the stall angle in normal flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;As visible in the image below, in upright flight the lower pressure is on the extrados of the wing. In inverted flight the lower pressure is on the intrados.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MQQ60.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MQQ60.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://hyperphysics.phy-astr.gsu.edu/hbase/fluids/airfoil.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air stream separation at the stall will occur on a side with different characteristics. One could expect the stall will happen differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;Equivalent representation, where the gravity is inverted and the wing orientation remains in the same direction. Flying inverted implies flying at a negative angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qIbrX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qIbrX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The values taken into account are the airflow direction and the chord line, reflected in the angle of attack value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;As commented, while the two previous images suggest a wing in horizontal flight, the situation can be extrapolated to any stable linear trajectory with a negative AoA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I2BJN.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I2BJN.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal plan or the pitch angle are not necessary to determine the stall angle (though they influence the stall &lt;em&gt;speed&lt;/em&gt;). &lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="22726" LastEditDate="2018-10-16T03:00:49.617" LastActivityDate="2018-10-19T04:31:01.663" Title="Does stall angle of attack in inverted flight change due to the camber of an asymmetric airfoil?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;&lt;aerobatics&gt;&lt;inverted-flight&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21038" PostTypeId="2" ParentId="21035" CreationDate="2015-09-17T20:01:08.680" Score="3" Body="&lt;p&gt;You are basically comparing a situation with positive $\alpha$ (above) with a situation with negative $\alpha$ (below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could obtain the same situation by pitching down: see how in the second picture your flow direction arrives from above the chord line (in the reference frame of the wing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your airfoil would have been symmetrical, the critical positive and negative $\alpha$ would have the same absolute value, only opposite sign, but you show a cambered airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I currently do not have my aerodynamics book at hand, but &lt;a href=&quot;https://books.google.de/books?id=JBTlucgGdegC&amp;amp;pg=SA43-PA5&amp;amp;lpg=SA43-PA5&amp;amp;dq=camber%20effect%20on%20lifting%20coefficient&amp;amp;source=bl&amp;amp;ots=auU1XlpUBe&amp;amp;sig=dU3LARygL2x0XK-1aUofNYJlKAQ&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0CEoQ6AEwCWoVChMIrLOxr-v-xwIVxgssCh1wvwKW#v=onepage&amp;amp;q=camber%20effect%20on%20lifting%20coefficient&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;google helps us&lt;/a&gt;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KWXVR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KWXVR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in the image, adding camber to an airfoil shifts its $C_{L\alpha}$ line towards negative values.&#xA;This is desirable because in this way you can have lift even when the angle of attack is 0 (and with no or little drag increase). Another consequence it that the maximum positive $\alpha$ will be smaller than the uncambered case and the negative one will be even more negative (but with some limitations, the Runge-Kutta condition at the trailing edge will affect the shape of the negative $C_{L\alpha}$ curve)&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-09-17T20:01:08.680" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21040" PostTypeId="1" AcceptedAnswerId="21042" CreationDate="2015-09-17T21:25:56.783" Score="11" ViewCount="5336" Body="&lt;p&gt;Here is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot; rel=&quot;noreferrer&quot;&gt;B-2 Spirit&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q0JL9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q0JL9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;a href=&quot;http://www.flugzeuginfo.net&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bczm7.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bczm7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;a href=&quot;http://www.the-blueprints.com&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many different things can get in the way with a design like a B-2. Although it has really good stealth and looks, does it have any disadvantages that come with the good stealth and looks?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What kind of disadvantages would this aircraft have of an&#xA;airliners design or another bombers design like the B-52 or B-1?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What system does this aircraft use to overcome not having&#xA;stabilizers?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Why have only 22 ever been built?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="15311" LastEditDate="2018-06-03T18:49:28.653" LastActivityDate="2020-10-14T22:53:02.530" Title="What are some disadvantages that come with a design like a B-2 spirit bomber?" Tags="&lt;military&gt;&lt;bomber&gt;&lt;strategic-bomber&gt;&lt;blended-wing&gt;&lt;b-2&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21041" PostTypeId="2" ParentId="21035" CreationDate="2015-09-17T21:26:59.800" Score="9" Body="&lt;p&gt;Short answer: Asymmetric airfoils have different positive and negative stall angles, the largest absolute value of the two depends on factors like nose shape and camber. With positive camber (normal and utility aircraft), the negative stall angle can be the largest (in absolute values) but the maximum negative lift available before stall will be smaller than for the positive stall. Larger Reynolds numbers push the stall further away in both directions&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on the airfoil. With symmetric airfoils, the stall angle is the same for positive and negative stalls. Positively cambered airfoils (the sort mostly used) have their negative stall at a smaller absolute value of the lift coefficient compared to their positive stall, but the stall angle can well be at a higher absolute value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see a polar plot for a supercritical airfoil which I used for &lt;a href=&quot;https://aviation.stackexchange.com/questions/13257/how-come-planes-can-endure-more-positive-than-negative-gs-i-e-how-come-v-n-di/13258?s=1%7C0.2157#13258&quot;&gt;this answer&lt;/a&gt;. The positive stall angle of attack is 8°, while the negative one is around -10°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/UAOmg.png&quot; alt=&quot;Polar plot of the R2A airfoil at Mach 0.6&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Polar plot of the R2A airfoil at Mach 0.6 (own work)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall angle depends on details of the nose contour and the camber: Positive camber means that the zero lift angle is shifted to negative values, so there is some bias to negative values in the polar. However, if the lower part of the nose has very high curvature, it will create a high suction peak which leads to flow separation just aft of the nose already at a small negative angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One extreme case would be the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=goe417-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;Göttingen 417a&lt;/a&gt; airfoil. Airfoiltools unfortunately plots only a range of Reynolds numbers suitable for model airplane enthusiasts, but the plot below should get the point across. The positive stall angle is 12° at the highest Reynolds number, while the negative stall angle is only around -8°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B81Bw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B81Bw.png&quot; alt=&quot;Gö 417 lift over angle of attack&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gö 417 lift over angle of attack. The lowest Reynolds number (blue line) is 50,000 and the highest is 1,000,000 (olive green line). Note that all curves are &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;nofollow noreferrer&quot;&gt;XFOIL&lt;/a&gt; predictions - real-world data might look differently.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-09-18T05:47:06.563" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21042" PostTypeId="2" ParentId="21040" CreationDate="2015-09-17T22:56:13.467" Score="9" Body="&lt;p&gt;The main problem with the B-2 Spirit (or any flying wing aircraft, for that matter) is that they are statically unstable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Hc1Y2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hc1Y2.jpg&quot; alt=&quot;Flying wing stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;a href=&quot;http://rdl.train.army.mil&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the lift vector of the wing acts before the center of gravity (as is the usual case when only wings are considered), any perturbation which results in an increase in angle of attack results in a positive moment about the center of gravity, which further increases the angle of attack an so on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only way to control such an aircraft is through computers, which continuously detect any changes in the aircraft attitude and apply corrections as required, as it is near impossible (or incredibly taxing) for human pilots to fly the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the method used in order to 'fly' the B-2 Spirit in the absence of a horizontal stabilizer. If there is any problem with the flight computer (which is remote) or with the sensors supplying data to it, the aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/2008_Andersen_Air_Force_Base_B-2_accident&quot; rel=&quot;nofollow noreferrer&quot;&gt;will become unflyable and crash&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another control issue with the B-2 is that the aircraft has little directional stability with no vertical tail. The swept wing offers some stability, though not in the same level as a vertical tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/boVdK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/boVdK.jpg&quot; alt=&quot;Aircraft Directional stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;a href=&quot;http://history.nasa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, only 21 of these were built, for the following reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The B-2 is costly; by costly I mean probably the most expensive aircraft ever built. With a total program cost of over 45b USD, each aircraft costs a whopping 2.1b USD (which was caused due to reduction in numbers from the initial 132). Also, the (hourly) operating costs of B-2 are twice that of other bombers in the USAF fleet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With the dissolution of the Soviet Union, the B-2 had effectively become an aircraft without a mission, as it was primarily designed to penetrate Soviet air defence systems.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="15311" LastEditDate="2018-06-03T17:40:29.033" LastActivityDate="2018-06-03T17:40:29.033" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="21043" PostTypeId="2" ParentId="19588" CreationDate="2015-09-17T23:06:12.093" Score="3" Body="&lt;p&gt;Development costs, complexity and need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a system that has to be hard real time multi-core is a pain(think expensive) and most things that need to be hard real time are not that complex. Things that don't need to be hard real time don't need to be RTOS, so you have one system that handles all the hard real time stuff and one that runs Linux and handles the other stuff. &lt;/p&gt;&#xA;" OwnerUserId="6854" LastActivityDate="2015-09-17T23:06:12.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21044" PostTypeId="1" AcceptedAnswerId="21048" CreationDate="2015-09-17T23:24:48.393" Score="-5" ViewCount="345" Body="&lt;p&gt;What is the reasoning for telling the public about an aircraft like the f-22 for example.&lt;a href=&quot;https://i.stack.imgur.com/j8zkL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j8zkL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;source:(commons.wikimedia.org)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Isn't the point of keeping an aircraft top secret so other countries won't know about this new technology this company came up with? Revealing this kind of technology to the public would allow other countries to know about it and design something better. The f-22 was released to the public in 2005, which gave China a good amount of time to try to design something better called the J-20.(better in certain areas)&lt;a href=&quot;https://i.stack.imgur.com/TSTZL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TSTZL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;source:(www.globalsecurity.org)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2015-09-19T10:31:35.593" LastActivityDate="2015-09-19T10:31:35.593" Title="Why are some aircraft finally announced to the public?" Tags="&lt;fighter&gt;" AnswerCount="3" CommentCount="4" ClosedDate="2015-09-18T03:44:56.130" ContentLicense="CC BY-SA 3.0" />
  <row Id="21046" PostTypeId="2" ParentId="21044" CreationDate="2015-09-17T23:43:21.527" Score="-3" Body="&lt;p&gt;The purpose of an aircraft like the F22 is to make your own people feel good about having the world's best fighter (or so you claim) and to sell it to your allies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was never really a secret from a serious superpower enemy.&lt;/p&gt;&#xA;" OwnerUserId="1576" LastEditorUserId="7532" LastEditDate="2015-09-18T15:37:35.033" LastActivityDate="2015-09-18T15:37:35.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21047" PostTypeId="2" ParentId="21044" CreationDate="2015-09-18T00:33:23.960" Score="4" Body="&lt;p&gt;There are a few reasons you disclose a project like this: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Intimidation:&lt;/strong&gt; You may want your adversaries to know that you have a weapon like this and exactly what its capable of. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Tax Payers:&lt;/strong&gt; To some extent you may want to keep your tax payers happy. While not every citizen pours over the budget of their government, considering what was spent on the F-22 or current F-35 it would be hard to not show people at least a bit of what you are working on for all that money. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now on a similar note you may not really be concerned about disclosing something like this. Keep in mind they are not disclosing the blueprints or through documentation on how the plane works. Seeing something and knowing what it can do are a far cry from designing and then physically constructing a bird like this. Take the SR-71 for example, it was in many regards not a secret but in the end of the day it was simply faster and more sophisticated than anything anyone threw at it and in its entire service history not a single one was lost and even when the enemy knew how fast it could go they still couldn't build anything to take it down.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-18T00:33:23.960" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21048" PostTypeId="2" ParentId="21044" CreationDate="2015-09-18T00:38:31.620" Score="4" Body="&lt;p&gt;An aeroplane is a large, highly visible object. Unless you're going to fly it only at night from remote airfields and can guarantee radar invisibility, the world will find out about it sooner or later. (Note that the F-117 Nighthawk is rumoured to have been in service for several years before it became public knowledge, flying under exactly these restrictions)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will also be large holes in public finance where funds have been used to pay for development, so anyone with an interest in seeing what a government has been up to can find out about such projects from public records (yes - we know that black projects can be hidden, but there is a limit to what one can get away with)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also easier to keep really important secrets if they're relatively small. Tell the world you have a bright shiny new aeroplane, with a whizz-bang rocket system, and the world won't look for the fancy gadget on the instrument panel that vaporises enemy jets electronically at a range of 500 miles. (Any resemblance to a real weapon is purely coincidental.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, anyone with a real interest in this new weapon system, such as a super-power enemy, has a pretty good idea what's going on anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Footnote: The J20 is a Chinese aeroplane, not Japanese. &lt;/p&gt;&#xA;" OwnerUserId="11272" LastActivityDate="2015-09-18T00:38:31.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21049" PostTypeId="2" ParentId="19088" CreationDate="2015-09-18T01:17:55.503" Score="1" Body="&lt;p&gt;for personal airplanes(like a Cessna),&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Expect to pay anywhere from $600 per year and up depending on the airplane, your time in type and total hours.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;source (&lt;a href=&quot;http://www.planeviz.com/cost-of-aircraft-ownership-ep-9/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.planeviz.com/cost-of-aircraft-ownership-ep-9/&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;while there are no estimates (that i can find) about the really big commercial airplanes like the 747, there are estimates available for smaller airplanes like the G650 ( &lt;a href=&quot;https://i.stack.imgur.com/1uvti.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1uvti.jpg&quot; alt=&quot;G650&quot;&gt;&lt;/a&gt; )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;the estimate for this plane in insurance is 60,000 USD per year&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source (&lt;a href=&quot;https://www.quora.com/What-are-the-yearly-maintenance-and-total-overhead-charges-for-a-65-million-Gulfstream-G650&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.quora.com/What-are-the-yearly-maintenance-and-total-overhead-charges-for-a-65-million-Gulfstream-G650&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastActivityDate="2015-09-18T01:17:55.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21050" PostTypeId="2" ParentId="19217" CreationDate="2015-09-18T01:40:33.820" Score="13" Body="&lt;p&gt;Short answer: an electronic logbook is legal; the FAA will accept almost anything as an endorsement; it's often most practical to collect endorsements on paper but electronic versions are also fine.&lt;/p&gt;&#xA;&lt;p&gt;First, the fundamental point about logbook formats is that the FAA defines &lt;em&gt;what&lt;/em&gt; you have to log (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.51&lt;/a&gt;), but not &lt;em&gt;how&lt;/em&gt; you log it. And &lt;a href=&quot;https://www.google.com/search?q=electronic%20pilot%20logbook&amp;amp;ie=utf-8&amp;amp;oe=utf-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;clearly&lt;/a&gt; electronic logbooks are &amp;quot;legal&amp;quot; in the sense that there's no law against using them.&lt;/p&gt;&#xA;&lt;p&gt;However, I suspect that the main question you're asking is, how can I gather endorsements in an electronic logbook? &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_61-65e.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 61-65E&lt;/a&gt; is essentially the FAA's practical guide to 14 CFR 61, and Appendix 1 lists recommended sample endorsements, with this comment:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The following examples are recommended sample endorsements for use by&#xA;authorized instructors when endorsing logbooks for airmen applying for&#xA;a knowledge or practical test, or when certifying accomplishment of&#xA;requirements for pilot operating privileges. Each endorsement must be&#xA;legible and include the instructor's signature, date of signature,&#xA;certificated flight instructor (CFI) or certificated ground instructor&#xA;(CGI) certificate number, and certificate expiration date, if&#xA;applicable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So it's clear that you need a &amp;quot;signature&amp;quot; from your instructor and for most people that means paper. But you might start questioning what a &amp;quot;signature&amp;quot; really is and if you can substitute something else. Fortunately the FAA has an entire AC &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_120-78_final.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;(AC 120-78)&lt;/a&gt; on electronic signatures that applies to part 61 and it says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;An electronic signature may be in the following forms.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A digital signature&lt;/li&gt;&#xA;&lt;li&gt;A digitized image of a paper signature&lt;/li&gt;&#xA;&lt;li&gt;A typed notation&lt;/li&gt;&#xA;&lt;li&gt;An electronic code&lt;/li&gt;&#xA;&lt;li&gt;Any other unique form of individual    identification that can be used as a means of authenticating a    record, record entry, or&#xA;document&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;That's a &lt;em&gt;very&lt;/em&gt; broad definition of an electronic signature, although it seems clear that the FAA wants it to be &amp;quot;individual&amp;quot; and non-repudiation is a requirement:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;An electronic signature should prevent a signatory from denying that&#xA;he or she affixed a signature to a specific record, record entry, or&#xA;document&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;However, there's also the practical question of how you collect endorsements. If you demand that your CFI creates an account in your logbook software, or generates his own digital certificate, or whatever else will make your electronic life easy, he may simply refuse. And how do get his endorsement when you're at that grass strip in the middle of nowhere with no cell signal or WiFi? How do you explain AC 120-78 to a skeptical DPE or FBO owner who's never heard of it before?&lt;/p&gt;&#xA;&lt;p&gt;In the end, the simplest solution is often to just to get a physical signature on a piece of paper with all the necessary information as per AC 61-65E. If you then want to go digital and shred the paper, you can always scan it and add it to your electronic logbook as per AC 120-78.&lt;/p&gt;&#xA;&lt;p&gt;But, if you want an electronic endorsement or signature and your CFI is willing to provide it, that's also fine. I use &lt;a href=&quot;https://myflightbook.com/logbook/Default.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;MyFlightbook&lt;/a&gt; for logging (no other connection and I'm not endorsing it) and their FAQ addresses whether electronic signatures are valid (links not preserved from the original):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The FAA does accept digital signatures, and outlines the criteria for&#xA;doing so in FAA circular AC No: 120-78A. While we believe MyFlightbook&#xA;is compliant with this AC (and we explain why we believe MyFlightbook&#xA;is compliant here), the FAA has thus far not indicated willingness to&#xA;even evaluate, much less certify, online logbook systems for&#xA;compliance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;My personal experience so far has been that DPEs have no problem with accepting electronic logbook printouts and endorsements. If something seemed suspicious then I assume they would investigate and ask some questions.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2020-09-04T04:37:56.190" LastActivityDate="2020-09-04T04:37:56.190" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21051" PostTypeId="1" CreationDate="2015-09-18T02:10:28.447" Score="7" ViewCount="293" Body="&lt;p&gt;I've my Sport Pilot licence and I've got logged hours with a sport pilot instructor that isn't a private pilot instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I use my logged instruction hours in order to upgrade to private pilot?&lt;/p&gt;&#xA;" OwnerUserId="11274" LastEditorUserId="1696" LastEditDate="2015-09-18T16:57:03.347" LastActivityDate="2015-09-18T16:57:03.347" Title="Do logged hours with a Sport Pilot instructor count towards a private pilot certificate?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21052" PostTypeId="2" ParentId="21051" CreationDate="2015-09-18T02:55:55.910" Score="6" Body="&lt;p&gt;No.  Sport pilot instructors are not authorized instructors with respect to private pilot certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8f2d411d76869d0aa65b96fa7fa5aa50&amp;amp;mc=true&amp;amp;node=se14.2.61_1109&amp;amp;rgn=div8&quot;&gt;61.109(a)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has issued a legal interpretation on the matter.  See the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/kern%20ink%20-%20(2009)%20legal%20interpretation.pdf&quot;&gt;Kern Ink interpretation&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-09-18T02:55:55.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21053" PostTypeId="1" CreationDate="2015-09-18T03:02:47.530" Score="3" ViewCount="257" Body="&lt;p&gt;I am Taiwanese and I have an FAA ATPL, but I don't have an FAA CPL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I fly commercial operations in the US? &lt;/p&gt;&#xA;" OwnerUserId="11276" LastEditorUserId="167" LastEditDate="2015-09-19T18:22:43.923" LastActivityDate="2015-09-19T18:22:43.923" Title="Can I fly in the USA with an FAA ATP, if I don't have a commercial certificate?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21054" PostTypeId="2" ParentId="21053" CreationDate="2015-09-18T03:18:20.780" Score="4" Body="&lt;p&gt;Yes.  If you have an ATP in the US it comes with all the privileges of a commercial license including flying for a 121 / 135 operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8f2d411d76869d0aa65b96fa7fa5aa50&amp;amp;mc=true&amp;amp;node=se14.2.61_1167&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;61.167&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;em&gt;Privileges&lt;/em&gt;. (1) A person who holds an airline transport pilot&#xA;  certificate is entitled to the same privileges as a person who holds a&#xA;  commercial pilot certificate with an instrument rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="62" LastEditDate="2015-09-18T13:03:04.330" LastActivityDate="2015-09-18T13:03:04.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21055" PostTypeId="1" CreationDate="2015-09-18T04:11:30.830" Score="18" ViewCount="1441" Body="&lt;p&gt;There was a &lt;a href=&quot;http://avherald.com/h?article=48c6c1aa&amp;amp;opt=0&quot;&gt;story&lt;/a&gt; in the news recently that an Air Canada 787-8, enroute from Tel Aviv (TLV) to Toronto (YYZ), diverted to Frankfurt (FRA) when the pilots discovered a problem with the cargo heat.  There was a live dog in the cargo hold, and the diversion potentially saved it from freezing to death.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The narrative has been that the pilots diverted &lt;em&gt;specifically&lt;/em&gt; in order to save the dog.  But I am wondering whether a cargo heat malfunction might require a diversion, as a matter of standard operating procedure, regardless of whether live animals are on board.  After all, even if there are no live animals, there might be other valuable temperature-sensitive cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, according to airline policies or procedures, under what circumstances would cargo heat failure warrant a diversion?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any major airline would be of interest; if you want a specific one, let's say Air Canada.&lt;/p&gt;&#xA;" OwnerUserId="2546" LastEditorUserId="100" LastEditDate="2020-05-11T09:47:41.510" LastActivityDate="2020-05-11T09:47:41.510" Title="Does cargo heat failure require a diversion? What about if there are live animals in cargo?" Tags="&lt;emergency-procedures&gt;&lt;cargo&gt;&lt;diversion&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21057" PostTypeId="2" ParentId="21006" CreationDate="2015-09-18T10:39:15.930" Score="6" Body="&lt;p&gt;It's probably fake but there's no reason why it couldn't be in and why it couldn't be approved like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An (The!) acceptable means of compliance to FAR/CS 23/25.1309 is DO-178. Airborne software is developed to meet a Design Assurance Level (DAL) which is derived from the aircraft level Functional Hazard Analysis and Preliminary System Safety Assessment (see SAE ARP 4761).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every FMC/FMS I've every worked on has been DAL C which means that the failure is 'Major' defined as the &quot;failure is significant, but has a lesser impact than a Hazardous failure (for example, leads to passenger discomfort rather than injuries) or significantly increases crew workload (safety related)&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For DAL C development, independence is only required for meeting the Software QA aspect. The software verification activity does not have to independent of the developer. However, for DAL C code, there is a requirement to complete full statement structural coverage, i.e. structure has to be tested at least once during the formal verification testing (i.e a decision has to be tested true OR false, not true AND false).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore the Software Verification Cases and Procedures (SVCP) would have to have had a test for the pong game in or else structural coverage would have shown the code to be 'Dead Code' and it would have to be removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The certification authority (FAA, EASA or otherwise) would not typically review the SVCP or the results (SVR).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The unit will also, most likely, have a Technical Standard Order (TSO) approval but as long as the performance requirements are met for the applicable TSO (e.g. TSO-C115c) the approval will be granted.&lt;/p&gt;&#xA;" OwnerUserId="11277" LastEditorUserId="6" LastEditDate="2015-09-30T17:27:54.033" LastActivityDate="2015-09-30T17:27:54.033" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21058" PostTypeId="2" ParentId="21012" CreationDate="2015-09-18T12:47:55.513" Score="1" Body="&lt;p&gt;As far as I know, and my searching for weird/unusual/concept aircraft has yet to reveal this type of design in use or proposed... even if it appears familiar or should have been proposed. The kicker here is the V-component. You can get tandem rudders, in various configurations, inverted V, V, split Vs, or V and elevators. The design here is V, split, with a T-top&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Hopefully someone that can explain the aerodynamics better will come along] Generally, this type of design would be considered redundant and too much extra weight for no general gain. A V type configuration will generally replace both the Rudder and Elevator into a single component. To then re-add an horizontal stabilizer would be redundant. Additionally you'd have to have more support structure in the V to be able to support the horizontal stabilizer and the forces it'd experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the image, it looks like a paper airplane, and if that type of design works, it's probably more due to the addition of more lifting surfaces that give aid towards better stability.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-09-18T12:47:55.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21059" PostTypeId="2" ParentId="21053" CreationDate="2015-09-18T13:09:20.190" Score="6" Body="&lt;p&gt;Maybe. Your ATP certificate does give you commercial privileges, as per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1167&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.167&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;em&gt;Privileges&lt;/em&gt;. (1) A person who holds an airline transport pilot&#xA;  certificate is entitled to the same privileges as a person who holds a&#xA;  commercial pilot certificate with an instrument rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But, that doesn't authorize you to work in the USA or even to enter the USA, which is an entirely different question about immigration law. As a foreigner, you'll need an appropriate visa or a green card in order to be legally employed and paid. You can ask more about that on &lt;a href=&quot;https://expatriates.stackexchange.com/&quot;&gt;another site&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:50:18.700" LastActivityDate="2015-09-18T13:09:20.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21061" PostTypeId="1" CreationDate="2015-09-18T17:30:49.243" Score="9" ViewCount="1434" Body="&lt;p&gt;How exactly does this equipment convert the F-16 into an unmanned aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to use this equipment on any other fighter (like the F/A-18 Hornet for example) in order to convert it into an unmanned aircraft? &lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="1467" LastEditDate="2018-02-15T14:19:06.343" LastActivityDate="2018-02-15T14:19:06.343" Title="What equipment is used by Boeing to convert the F-16 into an unmanned aircraft (QF-16)?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;fighter&gt;&lt;f-16&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21062" PostTypeId="2" ParentId="21061" CreationDate="2015-09-18T19:08:48.510" Score="5" Body="&lt;p&gt;I doubt it would be possible to give you a detailed and specific answer to this question (with a components list and such) - the US government and military contractors generally don't divulge complete plans and schematics for aircraft/modifications in active service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In basic theory however, I can tell you that &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Negative_stability_and_fly-by-wire&quot; rel=&quot;noreferrer&quot;&gt;the F-16 is a fly-by-wire aircraft&lt;/a&gt;. Much like an Airbus aircraft, all flight controls are actually manipulated by the on-board computers, and the pilot is just telling the computer what they would like the plane to do.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because it's a fly-by-wire aircraft all that's really needed to turn it into an &lt;em&gt;unmanned&lt;/em&gt; aircraft is to change the source of the &quot;pilot input&quot; from a control stick and throttle handle to a radio receiver that's getting commands from the ground, effectively turning it into the world's most expensive RC aircraft. Presumably there are also failsafes in the event the control uplink is lost, and at least some &lt;em&gt;basic&lt;/em&gt; security protocols to prevent someone else from sending commands to the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the &lt;a href=&quot;http://www.boeing.com/defense/support/qf-16/index.page&quot; rel=&quot;noreferrer&quot;&gt;QF-16&lt;/a&gt; (which is designed to serve as a target drone for aerial combat training) not much more needs to go into the design - it doesn't need extensive fire control capability for example. It also gets some other features added which are designed to aid in scoring training exercises (determining the accuracy of the aircraft attacking the target drone).&lt;br&gt;&#xA;If it were to go into a combat role it would require those features as well, and probably substantially more work in securing the control uplink so an enemy can't disrupt (or worse, hijack) control of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As to what would have to go into another aircraft to make it unmanned, that depends on the aircraft. Obviously the control uplink has to be installed so you can communicate with it from the ground. Control system modifications may be required as well, particularly if the aircraft is not &quot;fly-by-wire&quot; computer-controlled (the QF-4, which was the QF-16's immediate predecessor based on the F-4 phantom, likely required servos to operate the throttle and other flight controls).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-18T19:08:48.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21063" PostTypeId="1" AcceptedAnswerId="21064" CreationDate="2015-09-18T21:47:21.023" Score="10" ViewCount="4643" Body="&lt;p&gt;I noticed this picture yesterday of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Bird_of_Prey&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bird of Prey&lt;/a&gt; and wondered about the wing design and what advantages would come with this unique wing design compared to other aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BGkCq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BGkCq.jpg&quot; alt=&quot;Bird of Prey&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:(www.wired.com)&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-09-18T21:49:41.080" LastActivityDate="2016-07-16T12:47:29.170" Title="What advantages come with the wing on the Boeing Bird of Prey?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21064" PostTypeId="2" ParentId="21063" CreationDate="2015-09-18T23:58:58.823" Score="14" Body="&lt;p&gt;The Boeing Bird of Prey is indeed a unique aircraft, wahich was an internal project rather than an X-Project funded by the government. It was primarily used as a technology demonstrator for low observable technologies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Bird of Prey is rather unusual for a wing only aircraft (in the sense that it had no stabilizer) that it was statically stable and required no correcting inputs from a computer. This stability was achieved by the lift generated by the chines in front of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is  closer look at the chines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y9GEY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y9GEY.jpg&quot; alt=&quot;Bird of Prey front close&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.freerepublic.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chines produce lift by generating vortices (similar to the delta wing). Basically, the chines produce seperated vortices on either side of the fuselage, which produces lift. According to adg.stanford.edu,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rather than reducing the lift of the wing, the leading edge vortices, increase the wing lift in a nonlinear manner. The vortex can be viewed as reducing the upper surface pressures by inducing higher velocities on the upper surface&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/u15if.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/u15if.png&quot; alt=&quot;Nose chine vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Effects of Vertical Tail and Inlet/Strake Geometry on Stability &#xA;of a Diamond-Wing Fighter Configuration&lt;/em&gt; by Mitchell E. Fossum et al., accessed through &lt;a href=&quot;http://enu.kz/&quot; rel=&quot;noreferrer&quot;&gt;http://enu.kz/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To compare how the chine generates lift similar to a delta wing, it is instructive to see the vortex flow patterns on a slender (cropped) delta wing with a chine forebody.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X6BJH.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X6BJH.png&quot; alt=&quot;Chine- Delta Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;On the Nonlinear Aerodynamic and Stability Characteristics of&#xA;a Generic Chine-Forebody Slender-Wing Fighter - Configuration&lt;/em&gt; by Gary E. Erickson and Jay M. Brandon, NASA Technical Memorandum 89447, labeling mine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a delta wing with a chine forebody shows the two vortices being generated from the chines and the highly sweptback wing, similar to the Bird of Prey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kWQGJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kWQGJ.png&quot; alt=&quot;Chine- Delta CFD&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aerodynamic Analysis of a Generic Fighter with a Chine &#xA;Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation&lt;/em&gt; by Tiger L. Jeans et al, accessed through calpoly.edu &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The forces acting on the longitudinal axis of the aircraft look something like this (I'm not sure of the exact values or locations), leading to a statically stable aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IXQeg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IXQeg.jpg&quot; alt=&quot;Bird of prey stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Profile from bj-o23.deviantart.com, others own work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chines also help in reducing the radar cross section, according to dictionary.sensagent.com (attributed to &lt;em&gt;The Radar Game&lt;/em&gt; by Rebecca Grant):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A standard leading edge extension joins to the fuselage at an angle while a chine is an extension of the curvature of the fuselage. Therefore chines avoid presenting corner reflectors or vertical sides to radars.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This design has since become standard in (Boeing) UAVs like X-45 etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another feature is that the fuselage sides are parallel to each other, helping in reducing the Radar Cross section by reflecting the radar waves away from source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XytXM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XytXM.jpg&quot; alt=&quot;Boeing Bird of Prey&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: gizmodo.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing design is rather unusual, a polyhedral section with dihedral (upwardly angled) inboard sections and anhedral (downwardly angled) outboard sections, which helped in stealth and stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ehw39.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ehw39.jpg&quot; alt=&quot;Bird of Prey front&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: soldiersystems.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing has a rather high sweep angle (~65 degrees) for a low speed aircraft, in order to improve stealth.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-19T11:17:49.100" LastActivityDate="2015-09-19T11:17:49.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21065" PostTypeId="2" ParentId="21061" CreationDate="2015-09-19T00:25:32.660" Score="10" Body="&lt;p&gt;THE USAF has had a program for converting manned aircraft into unmanned ones for decades. The aircraft used so far include,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;QF- 104 (from F-104 Starfighter)&lt;/li&gt;&#xA;&lt;li&gt;QF- 102 (from F-102 Delta Dagger)&lt;/li&gt;&#xA;&lt;li&gt;QF- 100 (from F-100 Super Sabre)&lt;/li&gt;&#xA;&lt;li&gt;QF- 106 (from F-106 Delta Dart)&lt;/li&gt;&#xA;&lt;li&gt;QF- 4 (from F-4 Phantom II)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mae2l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mae2l.jpg&quot; alt=&quot;QF-16 and F-4&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that both aircraft are piloted. According to fencecheck.com,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(QF-4s are)..almost always flown with a pilot aboard, unless a weapons launch will occur. Usually he does not touch the controls but stands ready to take over if ground control is lost or the aircraft departs. The pilots fly the aircraft themselves on chase missions and to maintain proficiency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The QF-16 replaces the QF-4. The conversion of (retired) F-16 to QF-16 involves the &lt;a href=&quot;http://www.f-16.net/f-16_versions_article29.html&quot; rel=&quot;noreferrer&quot;&gt;following steps&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Removal of non essential items like the Vulcan cannon and the radar (in previous versions like QF-4, the radar was simply deactivated)&lt;/li&gt;&#xA;&lt;li&gt;Modification of the FCS (Flight Control System) so that &lt;em&gt;both manned and unmanned&lt;/em&gt; flights are possible (previous drones were remotely flown)&lt;/li&gt;&#xA;&lt;li&gt;Installation of Flight termination system to destroy drone in case of flight path deviation, which results in this:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JEbZL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JEbZL.jpg&quot; alt=&quot;QF- 16 destroyed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: f-16.net&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Installation of onboard telemetry systems to control the aircraft from the ground.&lt;/li&gt;&#xA;&lt;li&gt;Installation of a scoring system to measure the missile success rate. This is required as most of the missiles are launched with dummy warheads or the flight path is programmed to evade the missiles, so that the costly aircraft could be reused. Only in a few cases are lethal missiles used.&lt;/li&gt;&#xA;&lt;li&gt;The self protection suite (flares, chaffs etc.) are usually left on the aircraft to provide a realistic engagement scenario.&lt;/li&gt;&#xA;&lt;li&gt;New paint job :), which looks like this:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zdZiY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zdZiY.jpg&quot; alt=&quot;QF- 16&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.wired.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to convert (any) other aircraft into drones. For fly by wire aircraft like F/A-18, only the software portion will change, but it is a minor thing.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-09-21T14:55:54.733" LastActivityDate="2015-09-21T14:55:54.733" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21066" PostTypeId="2" ParentId="20956" CreationDate="2015-09-19T01:09:09.947" Score="6" Body="&lt;p&gt;As a Bay Area pilot, I've wondered this too.  It appears to be an &lt;strong&gt;unofficial but widely-understood local custom&lt;/strong&gt;, similar to the not-always-charted VFR reporting points commonly in use at many local airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, it seems there isn't just one &quot;Bay Tour&quot;.  Instead, I think that phrase generally tells the controllers that you're on a sightseeing flight rather than simply trying to get from point A to point B. &lt;/p&gt;&#xA;" OwnerUserId="8461" LastActivityDate="2015-09-19T01:09:09.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21068" PostTypeId="2" ParentId="21063" CreationDate="2015-09-19T08:53:19.190" Score="14" Body="&lt;h2&gt;Background&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Since @aeroalias' answer just reproduces what is said in Wikipedia, I will add a few more thoughts (albeit without the pictures, there are already plenty in the other answer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, the design is meant for transsonic flight, but the development was privately funded by &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas&quot; rel=&quot;nofollow noreferrer&quot;&gt;McDonnell-Douglas&lt;/a&gt; and had to keep cost down. As a consequence, the demonstrator aircraft used a 3000 lb thrust class engine (&lt;a href=&quot;http://www.pwc.ca/en/engines/jt15d&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney Canada JT15D5C&lt;/a&gt;) which is used more in military trainers and business jets than in combat aircraft. This kept the aircraft's top speed and the aerodynamic forces low, which helped in keeping the systems simple and the structure small. A production aircraft would be much bigger and use a much more powerful engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When McDonnell-Douglas was not selected for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Advanced_Tactical_Fighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATF program&lt;/a&gt; in the late Eighties, they decided to put themselves on the map by building a demonstrator which should show off their low-observables expertise. They had founded their own design office for black programs, called &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Phantom_Works&quot; rel=&quot;nofollow noreferrer&quot;&gt;Phantom Works&lt;/a&gt;, mirroring the approach of Lockheed with their &lt;a href=&quot;https://en.wikipedia.org/wiki/Skunk_Works&quot; rel=&quot;nofollow noreferrer&quot;&gt;Skunk Works&lt;/a&gt; branch.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The aircraft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Roughly half of the lift in level flight is produced by the forward fuselage. Wikipedia says it is the chines, but they only provoke the generation of a pair of vortices just like those on a delta wing, and the low pressure caused by the speeds of this vortex creates lift on the forward fuselage. In a way, the Bird of Prey is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21000/what-is-a-canard&quot;&gt;canard aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other half of lift is contributed by the wings, which again create vortex lift due to the high leading edge sweep angle. The dihedral of the inner wing was chosen to&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;get the tips up, so the winglets/fins have enough space to point downwards. Note that the tips of the winglets are cut back to provide enough clearance for rotation. This cutback angle also indicates the rotation angle and the angle of attack at low speed.&lt;/li&gt;&#xA;&lt;li&gt;provide a negative rolling moment due to sideslip, reducing the winglets' effect.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Regular, upward-pointing winglets have a number of disadvantages, one of them their &lt;a href=&quot;https://aviation.stackexchange.com/questions/19368/why-dont-airliners-have-rudders-on-the-winglets/19409?s=2%7C0.2184#19409&quot;&gt;induction of lift on the wing when their rudders are deflected&lt;/a&gt;, which produces an undesired rolling moment and prevents rolling the aircraft into the intended turn. Downward-pointing winglets helped to make the aircraft flyable without computer control, because they help with&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;directional stability, possible by their rear position due to the high wing sweep angle&lt;/li&gt;&#xA;&lt;li&gt;rolling moment with rudder deflection, rolling the aircraft into the direction of the turn commanded by the rudders.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The high sweep angle was chosen for the high-subsonic flight regime of any production version and for deflecting the returning radar signal away from the sender. The Bird of Prey is a two-lobe design (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/1798/do-similar-angles-on-a-plane-make-it-more-stealthy/12652?s=1%7C0.1647#12652&quot;&gt;this answer&lt;/a&gt; for more details)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-07-16T12:47:29.170" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21069" PostTypeId="1" AcceptedAnswerId="21072" CreationDate="2015-09-19T11:19:59.307" Score="28" ViewCount="16024" Body="&lt;p&gt;In a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21063/what-advantages-come-with-the-wing-on-the-boeing-bird-of-prey&quot;&gt;recent question&lt;/a&gt; I asked, I was given an answer by &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;Peter Kämpf&lt;/a&gt; and he described something about lift being created by a vortex used on delta wings and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Bird_of_Prey&quot; rel=&quot;noreferrer&quot;&gt;Bird of Prey&lt;/a&gt; wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How exactly does vortex lift form to generate lift and on what other types of wing is it used on?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-09-20T07:01:27.637" Title="What is vortex lift?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21070" PostTypeId="1" AcceptedAnswerId="21073" CreationDate="2015-09-19T13:12:56.717" Score="10" ViewCount="1878" Body="&lt;p&gt;Spins cannot occur without stalls. To enter a spin, a pilot would hold the elevator up and let speed bleeds off. This is how you'd approach a stall. Just as the stall starts to develop, apply full rudder; now the world is spinning around you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, how does one enter an inverted spin? How do you stall an aircraft while it is inverted?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="22726" LastEditDate="2019-09-25T02:44:17.137" LastActivityDate="2019-09-25T23:03:06.483" Title="How to enter an inverted spin?" Tags="&lt;aerobatics&gt;&lt;spins&gt;&lt;inverted-flight&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21071" PostTypeId="2" ParentId="21069" CreationDate="2015-09-19T13:15:21.220" Score="21" Body="&lt;h2&gt;What it is&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Vortex lift needs two conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High leading edge sweep (ideally 60° and above)&lt;/li&gt;&#xA;&lt;li&gt;High angle of attack, the more sweep, the smaller the angle when vortex lift becomes effective.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Vortex lift is caused by flow separation at the leading edge. While this indicates a severe stall on unswept wings, the separated flow along a highly swept edge will roll up and will produce a conical, stable vortex. The speeds due to this helical movement of air cause air pressure over the wing to drop, which provides the suction that produces the lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the angle of attack is increased further, the vortex becomes unstable and bursts. If this happens while it is still over the wing, the aircraft becomes unstable - the bursting of the vortex is a highly dynamic process, leading to buffet and an unstable, self-reinforcing rolling motion.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Where else is vortex lift used?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Vortex lift is helpful when lift is needed at high angles of attack or sideslip. Besides on &lt;a href=&quot;https://aviation.stackexchange.com/questions/4994/why-delta-wings-are-not-commonly-used-in-commercial-airliners/5002#5002&quot;&gt;delta wings&lt;/a&gt;, it is used in:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15637/stall-delay-by-using-leading-edge-root-extensions/16372#16372&quot;&gt;Strakes or leading edge extensions ahead of the wing&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14786/what-is-the-purpose-of-a-dorsal-fin-such-as-on-the-boeing-737&quot;&gt;Strakes or fillets ahead of the vertical tail surface&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12659/which-type-of-control-gives-a-more-agile-missile-tail-or-canard/12666?s=1%7C0.1170#12666&quot;&gt;highly swept canards or fins&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Pretty pictures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/pu23e.jpg&quot; alt=&quot;CFD simulation of high alfa flight&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of CFD simulations on the F-18, taken from &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;this Aerospaceweb&lt;/a&gt; page.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The grey ribbons show how the flow curls up past the leading edge of the strake and stays close to the upper surface of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LSeJ9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LSeJ9.jpg&quot; alt=&quot;Flow visualtsation on delta wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow visualisation on a delta wing (picture &lt;a href=&quot;http://www.network54.com/Forum/211833/thread/1209515870/Delta+canard+formula&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). This picture was taken in a water tunnel, and dyes were injected at the leading edge to make the streamlines visible. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-19T13:31:06.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21072" PostTypeId="2" ParentId="21069" CreationDate="2015-09-19T13:55:46.933" Score="25" Body="&lt;p&gt;The vortex lift is the method by which highly swept wings (like delta wings) produce lift at high angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of wings having sharp, highly swept leading edges like delta wings, the leading-edge separation vortex phenomenon occurs at subsonic speeds. However, the separation does not destroy the lift as in the case of low sweep wings; instead, it forms two vortices which are (nearly) parallel to the wing edges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mIuVd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mIuVd.jpg&quot; alt=&quot;Vortex over Delta Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortices over a delta wing with a sweep angle of 70°, &lt;em&gt;Separation in three-dimensional steady flow&lt;/em&gt;, ONERA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of Concorde, the vortices look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uMsTO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uMsTO.jpg&quot; alt=&quot;Concorde Wing Vortices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortices over the Concorde wing, &lt;em&gt;Separation in three-dimensional steady flow&lt;/em&gt;, ONERA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cross-section of the vortices looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HqwPb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HqwPb.jpg&quot; alt=&quot;Flow above Concorde Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow above the Concorde Wing, &lt;em&gt;Separation in three-dimensional steady flow&lt;/em&gt;, ONERA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike the (bound) vortex of the conventional wing, these are real in the sense that they represent an actual mass of air rotating at high speed compared to the air in front of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vortices form 'vortex sheets' along the wing. Air is sucked into the vortex sheets and accelerated downward. As the airspeed in the vortex is high, the pressure is low. This low presssure on the upper surface produces lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;em&gt;Low Aspect Ratio Wings at High Angles of Attack&lt;/em&gt; at adg.stanford.edu:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the leading edge vortices, increase the wing lift in a nonlinear manner. The vortex can be viewed as reducing the upper surface pressures by inducing higher velocities on the upper surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/auIYi.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/auIYi.gif&quot; alt=&quot;Lift due to Vortices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the vortices increase the lift from the baseline (potential flow) values, with the extra force being equal to the loss of leading edge suction associated with the separated flow in high angle of attack highly swept wings. This analogy gives the same result as before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qvqSa.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qvqSa.png&quot; alt=&quot;Vortex lift in delta wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A Concept of the Vortex Lift of Sharp-Edge Delta Wings based on a Leading-Edge suction Analogy&lt;/em&gt;, Edward C. Polhamus, NASA Technical note D-3767&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A major advantage of vortex lift generation is that it is effective at high angles of attack, over which the wings would normally stall. Actually, that Concorde used this method of lift generation is the reason for the high AoA during landing and its droop down nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Rx67Y.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rx67Y.jpg&quot; alt=&quot;Lift cure comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://soliton.ae.gatech.edu&quot; rel=&quot;noreferrer&quot;&gt;http://soliton.ae.gatech.edu&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to be noted is that vortex lift generation happens at high angles of attack or in case the wings are designed to generate separated flow (with sharp edges as in Concorde) in normal conditions. Otherwise the lift generation is by conventional means. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same mechanism is responsible for lift generation in:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Strakes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O0h2f.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O0h2f.jpg&quot; alt=&quot;F-18 Strake Vortices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By U.S. Navy photo by Mass Communication Specialist 2nd Class James R. Evans [Public domain], via Wikimedia Commons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Chines&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yzbue.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yzbue.png&quot; alt=&quot;Nose Chine Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Effects of Vertical Tail and Inlet/Strake Geometry on Stability of a Diamond-Wing Fighter Configuration&lt;/em&gt; by Mitchell E. Fossum et al., accessed through &lt;a href=&quot;http://enu.kz/&quot; rel=&quot;noreferrer&quot;&gt;http://enu.kz/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Canards&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tQyks.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tQyks.png&quot; alt=&quot;Su 30 Canard Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: forum.keypublishing.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9276" LastEditDate="2015-09-20T07:01:27.637" LastActivityDate="2015-09-20T07:01:27.637" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21073" PostTypeId="2" ParentId="21070" CreationDate="2015-09-19T14:24:01.817" Score="13" Body="&lt;p&gt;When inverted, cut power. As speed bleeds off, gradually move stick forward keep your flight level, the nose will come up quite a bit over the horizon. It is important not to start sinking here as that will prevent the speed coming down low enough. When the stick hits the forward stop, kick in full rudder either way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Enjoy!&lt;/p&gt;&#xA;" OwnerUserId="7892" LastActivityDate="2015-09-19T14:24:01.817" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21074" PostTypeId="2" ParentId="20778" CreationDate="2015-09-19T15:38:29.030" Score="2" Body="&lt;p&gt;As an early active air traffic controller in cuba I can tell that MIA ARTCC people were the best to work with,and jamaica the other end, meaning the worst ones,all guys in MIA had a great relationship with us ,of course havana had some bad apples regarding supervisor coordinations but other than everything was fine,they were our model to imitate  actualy met couple of controllers that went to Cuba and had a great time with them.&lt;/p&gt;&#xA;" OwnerUserId="11292" LastActivityDate="2015-09-19T15:38:29.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21075" PostTypeId="5" CreationDate="2015-09-19T16:35:06.183" Score="0" Body="&lt;p&gt;Regions on the Earth's surface (or in its atmosphere) that are high above mean sea level (MSL) are referred to as high altitude. High altitude is sometimes defined to begin at 2,400 meters (8,000 ft) above sea level. Altitude sickness commonly occurs above this level.&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastEditorUserId="22726" LastEditDate="2019-09-07T03:58:17.207" LastActivityDate="2019-09-07T03:58:17.207" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21076" PostTypeId="4" CreationDate="2015-09-19T16:35:06.183" Score="0" Body="Regions on or above the earth's surface located at least 2,400 meters (8,000 ft) above sea level." OwnerDisplayName="user8732" LastEditorUserId="22726" LastEditorDisplayName="user8732" LastEditDate="2019-09-07T03:58:01.523" LastActivityDate="2019-09-07T03:58:01.523" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21077" PostTypeId="1" AcceptedAnswerId="21078" CreationDate="2015-09-19T18:37:26.603" Score="14" ViewCount="8800" Body="&lt;p&gt;I understand that blocks of transponder codes are assigned to different area controls. I am curious if the block 7701 to 7777 is in use anywhere? Maybe the emergency code 7700 needs some extra protection?&lt;/p&gt;&#xA;" OwnerUserId="7892" LastActivityDate="2019-07-12T02:36:25.243" Title="Are transponder codes 7701 - 7777 ever used?" Tags="&lt;emergency&gt;&lt;transponder&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21078" PostTypeId="2" ParentId="21077" CreationDate="2015-09-19T20:31:42.393" Score="12" Body="&lt;p&gt;Yes these codes are used. Only 7700 is used to denote emergencies, and usually only if you aren't in contact with ATC, or can't get their attention(frequency is packed). Codes in this range are allocated according to the National Beacon Assignment Plan in the US. There are other codes that are assigned for various issues, 7777 as mentioned in the comments is assigned, and I've assigned others in that range before, same with the 7600 and 7500 ranges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're already in contact with ATC, and they have you tagged, it is very easy to mark you as an emergency and have it light up on everyone in the facility's scope.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-09-19T20:31:42.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21080" PostTypeId="1" CreationDate="2015-09-19T21:11:10.070" Score="1" ViewCount="988" Body="&lt;p&gt;I wish to buy a single engine light aircraft. I have a FAA ppc. I wish to buy an N reg plane and use it outside the US. I believe I need to have a trust set up any info would be appreciated. I am not a US citizen&lt;/p&gt;&#xA;" OwnerDisplayName="user11295" LastEditorDisplayName="user11295" LastEditDate="2015-09-19T21:16:10.670" LastActivityDate="2015-09-20T15:03:10.273" Title="How does a non US pilot buy a N reg plane?" Tags="&lt;faa&gt;&lt;aircraft-purchase&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2015-09-21T16:02:04.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="21081" PostTypeId="1" AcceptedAnswerId="21091" CreationDate="2015-09-19T21:18:51.880" Score="10" ViewCount="9883" Body="&lt;p&gt;The F-22 has square nozzles, while the Russian Sukhoi PAK FA has circular nozzles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are both 5th generation planes, but with different nozzles, why?&lt;/p&gt;&#xA;" OwnerUserId="11256" LastEditorUserId="1467" LastEditDate="2018-02-15T14:16:26.283" LastActivityDate="2019-08-10T13:26:47.237" Title="Advantages of square over circular engine nozzle?" Tags="&lt;jet-engine&gt;&lt;fighter&gt;&lt;f-22&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21082" PostTypeId="1" AcceptedAnswerId="21084" CreationDate="2015-09-19T21:39:51.263" Score="12" ViewCount="3559" Body="&lt;p&gt;Why do VTOL aircraft (F-35 or Harrier) have only one engine? Is it because it is simpler and less expensive? Or what are the reasons?&lt;/p&gt;&#xA;" OwnerUserId="11256" LastEditorUserId="1467" LastEditDate="2017-02-08T14:42:52.843" LastActivityDate="2017-12-05T01:41:39.837" Title="Why do VTOL aircraft (F-35 or Harrier) have only one engine?" Tags="&lt;engine&gt;&lt;jet&gt;&lt;fighter&gt;&lt;vtol&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21084" PostTypeId="2" ParentId="21082" CreationDate="2015-09-20T02:44:52.120" Score="19" Body="&lt;p&gt;VTOL aircraft can have more than one engine. It is just that the design process of the Harrier and F-35 led to a situation where only one engine was required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main challenge in any VTOL aircraft is to have the engine produce thrust in two different phases of flight: during cruise and during takeoff/landing. This basically requires the powerplant on the aircraft to have two different characteristics at those two phases, because&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The direction of the thrust vector is different in TO/Landing and cruise&lt;/li&gt;&#xA;&lt;li&gt;Amount of thrust required is different; for vertical TO, the thrust should be more than the weight while in cruise, the required thrust is (comparatively) pretty low.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A number of approaches have been tried to solve this problem: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Takeoff the aircraft vertically (aka the tail sitter), like &lt;a href=&quot;https://en.wikipedia.org/wiki/Ryan_X-13_Vertijet&quot; rel=&quot;noreferrer&quot;&gt;Ryan X-13 Vertijet&lt;/a&gt;, and then transition to horizontal flight. However, one major problem is the pilot has severe disorientation problems during transition&lt;/li&gt;&#xA;&lt;li&gt;Put extra fans, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ryan_XV-5_Vertifan&quot; rel=&quot;noreferrer&quot;&gt;Ryan XV-5 Vertifan&lt;/a&gt;. The problem was the large (wing) area taken up by the fan and weight penalties. Ironically, a similar concept has been used in F-35&lt;/li&gt;&#xA;&lt;li&gt;Put extra engines specifically for vertical lift (aka the 'Rolls Royce Concept'), used in &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Balzac_V&quot; rel=&quot;noreferrer&quot;&gt;Dassault Mirage Balzac&lt;/a&gt;. Though this offered (theoretically) better safety, the weight penalty was too much.&lt;/li&gt;&#xA;&lt;li&gt;Optimise the main engine for cruise and deflect the thrust for takeoff and augment with (small) lift engines (aka the tiltjet concept), like the German &lt;a href=&quot;https://en.wikipedia.org/wiki/EWR_VJ_101&quot; rel=&quot;noreferrer&quot;&gt;EWR VJ 101&lt;/a&gt;. This reduced the weight penalty and complexity, but reduced safety in the event of an engine failure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In order to avoid the weight penalty, the best approach is to have no extra engines at all, with the thrust deflected down at take off and landing. This was called 'vectored thrust' (a term attributed to Theodore Von Karman). This concept was tested in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_X-14&quot; rel=&quot;noreferrer&quot;&gt;Bell X-14&lt;/a&gt;, which had fixed eingines and thrust vectoring vanes that deflected the exhaust to achieve vertical lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9TOKB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9TOKB.jpg&quot; alt=&quot;Bell X-14&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: history.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the Harrier, the engine, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Pegasus&quot; rel=&quot;noreferrer&quot;&gt;Bristol Siddeley Pegasus&lt;/a&gt; was first developed (as BE.53) and the Hawker aircraft decided to develop an aircraft around it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the design proces, the aircraft was redesigned around the Hawker modified BE 53 which the rear jet was split into two, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Sea_Hawk&quot; rel=&quot;noreferrer&quot;&gt;Hawker Sea Hawk&lt;/a&gt;, which had a similar arrangement. This lead to the 'four poster' thrust vectoring system in the  Harrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SXzxO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SXzxO.jpg&quot; alt=&quot;Four poster thrust vectoring system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.aerospaceweb.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason, the Harrier had a single engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The case of F-35 is different. The F-35 was designed to replace aircraft operated by a number of US services, and as such had conflicting design requirements. At one end, the USAF wanted a conventional fighter while the USMC wanted a VTOL aircraft. The USN requirements were somewhere in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed designers decided that the best way to meet these requirements is to have a separate fan for lifting the aircraft in VTOL, which can simply be eliminated in the USAF and USN variants. This led to the lift fan arrangement (eerily similar to the Vertifan arrangement).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vapnl.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vapnl.png&quot; alt=&quot;F-35 Lift fan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-35B_Joint_Strike_Fighter_(thrust_vectoring_nozzle_and_lift_fan).PNG#/media/File:F-35B_Joint_Strike_Fighter_(thrust_vectoring_nozzle_and_lift_fan).PNG&quot; rel=&quot;noreferrer&quot;&gt;F-35B Joint Strike Fighter (thrust vectoring nozzle and lift fan)&lt;/a&gt;&quot; by Tosaka - Own work. Licensed under CC BY 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in case of F-35 the use of a single engine was the best way to meet the requirements. The engine used, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney F135&lt;/a&gt; is the most powerful fighter jet engine in service, which helps in making F-35 the first supersonic VTOL aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="598" LastEditDate="2016-09-30T10:39:00.800" LastActivityDate="2016-09-30T10:39:00.800" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21085" PostTypeId="2" ParentId="1682" CreationDate="2015-09-20T03:10:28.840" Score="11" Body="&lt;p&gt;Yes and no.  Gimbal lock is a physical AND mathematical phenomenon.  Physically, gimbals sharing the same axis can cause a lock, and mathematically, a representation of a multi-axis rotation can be in a condition which is singular, depending on how it is represented and calculated internally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, we discuss and think about aircraft attitude intuitively as set of angles: roll, pitch and heading.  In mathematical circles, this is known as a set or 3-2-1 Euler angles.  If you look into the boring (or exciting, if you are that kind of person) &lt;a href=&quot;http://malcolmdshuster.com/Pub_1993h_J_Repsurv_scan.pdf&quot;&gt;math&lt;/a&gt;, you can see a vector-matrix equation relating the change in Euler angles given a set of angular rates given in the frame of the aircraft, by common convention these are referred to as p, q and r for roll rate, pitch rate, and yaw rate respectively.  The way these rates affect the change in the angles depends on the current state of the the angles, e.g. when the aircraft is pitched, a body-frame yaw rate will alter the pitch angle.  Mathematically, this means that the &quot;state matrix&quot; is state-dependent and must be constantly updated using the freshest set of states available.  Any set of Euler angles will have a set of states which causes the state matrix to become poorly conditioned, resulting in numerical instability at those conditions.  For the roll-pitch-heading set of angles, this happens when pitch is + or - 90 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way that we escape the singularities when writing the software for an AHRS is by representing the attitude in a non-singular form.  This done by using more numbers to create the representation, then adding constraints which preserve uniqueness.  A 3x3 direction cosine matrix (DCM) can do this,  It has constraints which cause it's eigenvalues to lie on a unit circle in the complex plane.  My favourite representation, however, is a quaternion constrained to have unit length.  The quaternion can be thought of in terms of &lt;a href=&quot;https://en.wikipedia.org/wiki/Euler&amp;#39;s_rotation_theorem&quot;&gt;Euler's rotation theorem&lt;/a&gt;.  There's that Euler guy again, he must have been some kind of genius.  Anyhow, the idea is that you can define an axis of rotation with three numbers, and use a fourth to represent an angle about that axis to rotate.  This gives you a system free of &quot;mathematical gimbal lock&quot;  The state matrix remains adequately conditioned under all states.  All you need to do to keep things friendly is to normalize the quaternion from time to time, and you always have a &quot;background&quot; state that you can translate into aviator-friendly Euler angles.&lt;/p&gt;&#xA;" OwnerUserId="182" LastActivityDate="2015-09-20T03:10:28.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21087" PostTypeId="1" CreationDate="2015-09-20T06:13:29.367" Score="4" ViewCount="144" Body="&lt;p&gt;I don't know if this is the right place for this question, but I guess it's related to aviation right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My grand uncle was a pilot in the South Vietnam Air Force. He served from 1964 to 1968. He flew F-5s and A-37s and crashed on a A-37.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being I student pilot now, I very much want to look back and find out what really caused his crash. My family fled Vietnam from the Communists when I was too young. I only remember seeing his Air Force Death Certificate in English which I didn't understand a word in it back then. I was told from multiple sources that his A37 blew up before taking off, and that he crashed soon after take-off... But I always wanted to see the actual result of an investigation if any.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do you think it is even possible to look up records for those dead ones who served for the South of Vietnam? (since I know they are considered forgotten in the history of the Vietnam War)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information about the accident that I can remember:&#xA;Date and time of the accident: 12/10/1968 9AM&#xA;Location: Pleiku Airbase, Vietnam&#xA;Aircraft: A-37&#xA;Name of pilot: Hai, Le Nguyen (Lê Nguyên Hải)&#xA;Pilot's rank: Lieutenant&#xA;Pilot's DOB: 12/09/1941&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks.&lt;/p&gt;&#xA;" OwnerUserId="9783" LastEditorUserId="9783" LastEditDate="2015-11-17T19:58:28.910" LastActivityDate="2015-11-17T19:58:28.910" Title="Where can I find records about accidents in the South Vietnam Air Force?" Tags="&lt;accidents&gt;&lt;accident-investigation&gt;&lt;ntsb&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-09-21T23:16:27.593" ContentLicense="CC BY-SA 3.0" />
  <row Id="21089" PostTypeId="2" ParentId="21080" CreationDate="2015-09-20T15:03:10.273" Score="3" Body="&lt;p&gt;The ownership requirements for registering an N-reg aircraft are discussed in &lt;a href=&quot;https://aviation.stackexchange.com/q/9375/62&quot;&gt;this question&lt;/a&gt;. The current &lt;a href=&quot;http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/register_aircraft/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA information&lt;/a&gt; says that the only options open to a non-resident foreigner are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A corporation or association:&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;organized under the laws of the U.S. or a State, the District of Columbia, or a U.S. territory or possession,&lt;/li&gt;&#xA;  &lt;li&gt;of which the president and at least two-thirds of the board of directors and other managing officers are U.S citizens, and&lt;/li&gt;&#xA;  &lt;li&gt;in which at least 75% of the voting interest is owned or controlled by persons that are U.S. citizens,&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;A non-U.S. citizen corporation organized and doing business under the laws of the U.S. or one of the States as long as the aircraft is&lt;br&gt;&#xA;  based and primarily used in the U.S. (60% of all flight hours must be &#xA;  from flights starting and ending within the U.S.)&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you either need a corporation that's majority controlled by US citizens, in which case there are no restrictions on flight activities; or, you can use a non-US citizen corporation but then most of the flight hours have to be in (or to/from) the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ideal way to go about this would be to find someone near you who's already done it. Many flight schools and individuals outside the US operate N-registered aircraft so you might be able to find someone who can tell you how they did it. You'll need to do this research anyway, because if you're basing an N-reg aircraft outside the US then you'll need to find an FAA mechanic near you who can legally perform maintenance on it. If your country has some kind of GA or pilot's association then you could ask them too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also look for companies (usually law firms) who specialize in doing this and get their advice and/or retain them to actually set up the ownership structure that you need. That's going to cost some money - and many firms are focused on business jets, not light singles - but it could be a minor cost compared to the aircraft and maintenance, depending on what you plan to buy. I found a few by Googling but a personal reference from someone near you would be a lot more useful. &lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-20T15:03:10.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21090" PostTypeId="1" AcceptedAnswerId="21110" CreationDate="2015-09-20T16:28:43.210" Score="9" ViewCount="1434" Body="&lt;p&gt;Today, I flew on a commercial airline European flight. Upon arrival, as I was walking from the airplane to the arrivals gate (across tarmac, no jetways), a yellow car labelled &quot;Airside inspection&quot; sped up to the plane with blue lights and sirens wailing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eHxgS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eHxgS.jpg&quot; alt=&quot;yellow car&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An officer ran out and blocked people from exiting the plane (some had already gotten out and were allowed to leave). Then, other two people in orange jackets followed him into the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Google searches for airside inspection don't produce a lot of material, but from what I could understand these people are charged with checking that the runways etc. conform to safety standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What reason would they have to approach a plane, sirens on, and block the passengers?&lt;/p&gt;&#xA;" OwnerUserId="3206" LastEditorUserId="3206" LastEditDate="2015-09-21T19:28:47.260" LastActivityDate="2015-09-21T19:45:14.913" Title="What is &quot;airside inspection&quot;?" Tags="&lt;airport&gt;&lt;security&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21091" PostTypeId="2" ParentId="21081" CreationDate="2015-09-20T18:32:05.603" Score="16" Body="&lt;p&gt;Circular nozzles have these advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They can be swiveled in any direction, so both pitch and yaw moments can be produced. Square nozzles only allow to create pitch forces, because their panels can only be moved around one axis. When moved differently in two-engined aircraft, limited roll moments are also possible.&lt;/li&gt;&#xA;&lt;li&gt;Round nozzles are lighter. As long as exhaust gas pressure is higher than outside pressure, a square nozzle will be subject to bending loads across the width of its panels. This will make a square nozzle much heavier than a round nozzle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Actually, square thrust vectoring nozzles have just one advantage: They can be made to reflect radar waves in a few well-defined directions, while round nozzles will scatter them all around. This makes square nozzles the preferred choice for stealth aircraft, regardless of thrust vectoring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UTxed.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UTxed.jpg&quot; alt=&quot;Engine nozzles of the F-22&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Engine nozzles of the F-22 (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/2/22/F22_Parked.jpg/800px-F22_Parked.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the serrated rear edges of the thrust vectoring panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ga81f.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ga81f.jpg&quot; alt=&quot;Engine exhausts of the B-2&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Engine exhausts of the B-2. Since the B-2 uses four non-afterburing engines, fixed nozzles are used. Their location helps to protect the airplane from detection by infrared (IR) sensors, but makes thrust vectoring impracticable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/D6i99.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D6i99.jpg&quot; alt=&quot;Engine nozzles of the YF-23&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Engine nozzles of the YF-23 (picture &lt;a href=&quot;http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=7152&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). The lower part is longer to shield the hot exhaust against IR sensors from below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the goal is to mostly reduce radar reflections in the forward hemisphere of the aircraft, round nozzles can be tolerated. Only when the aircraft needs to be protected from radar-guided missiles fired from behind will the square nozzles give a clear advantage. It seems that the people behind the Sukhoi PAK FA (and other stealth fighters like the &lt;a href=&quot;http://www.fastcompany.com/1716168/chinas-stealth-fighter-flies-does-it-work-ripping-us-tech&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chinese J-20&lt;/a&gt;) do not worry so much about this detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Zyv30.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zyv30.jpg&quot; alt=&quot;Sukhoi T-50&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Sukhoi T-50 (prototype for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_PAK_FA&quot; rel=&quot;nofollow noreferrer&quot;&gt;PAK FA program&lt;/a&gt;) from below (picture by &lt;a href=&quot;http://www.airliners.net/photo/Russia---Air/Sukhoi-T-50/1970458/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dmitry Pichugin&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iX1An.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iX1An.jpg&quot; alt=&quot;Chengdu J-20 rear view&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Chengdu J-20 rear view (picture &lt;a href=&quot;http://pic2.xilu.com/xilupic/20120112040234642.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, even Lockheed-Martin and Pratt &amp;amp; Whitney now place maneuverability and weight over stealth in their nozzle design for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_F135&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-135&lt;/a&gt; engine of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-35&lt;/a&gt; strike aircraft. Note the serrated edges on all contour steps. This helps to reduce radar returns, but is much less effective than a square nozzle. The benefit is less weight and better maneuverability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/faUYh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/faUYh.jpg&quot; alt=&quot;F-135 nozzle&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;F-35 with the F-135 nozzle visible (Picture &lt;a href=&quot;https://arcturus415.files.wordpress.com/2013/08/sdd_f35testc_049.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2019-08-09T11:12:14.640" LastActivityDate="2019-08-09T11:12:14.640" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="21092" PostTypeId="1" AcceptedAnswerId="21094" CreationDate="2015-09-20T21:44:12.420" Score="2" ViewCount="9943" Body="&lt;p&gt;I am studying a text entitled &lt;em&gt;Unmanned Aircraft Systems&lt;/em&gt;. How can we simplify the instruction in quotes so that it is more understandable and can be understood by a nontechnical. Please note I am not seeking to know all technical jargon of routing aircraft, rather to get what a pilot is told with this instruction to do.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ideally, the communication process includes three parts: the&#xA;  initial call, readback, and hearback. For example, an ATCO would issue an instruction “American 755, turn right, heading 320.” Pilots onboard the aircraft would respond, or readback the message “Right, heading 320, American 755.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11255" LastEditorUserId="6886" LastEditDate="2015-09-21T06:10:28.213" LastActivityDate="2017-03-24T16:44:08.007" Title="What is the meaning of “American 755, turn right, heading 320&quot;?" Tags="&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21093" PostTypeId="2" ParentId="21092" CreationDate="2015-09-20T21:54:06.890" Score="6" Body="&lt;p&gt;The basic answer is that the controller is instructing American 755 to turn right in order to point the airplane a direction which is 320 degrees clockwise from due north (basically northwest)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the specifics of what a &quot;heading&quot; is, &lt;a href=&quot;https://aviation.stackexchange.com/a/8947/167&quot;&gt;see this excellent answer (with pictures!)&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-20T21:54:06.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21094" PostTypeId="2" ParentId="21092" CreationDate="2015-09-20T22:29:37.967" Score="10" Body="&lt;p&gt;It is quite simple if you look into the answer linked by Steve V. to understand what the headings are. Here is a simple example: aircraft flies at 290. Controller instructs right turn to 320. The image below shows how should the aircraft turn. Heading is on top and on the orange &quot;bug&quot;. (Needle shows track but you can safely ignore it for this example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E0oka.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E0oka.png&quot; alt=&quot;Short turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But here is a subtle case: if the aircraft flies on a heading of let's say 030 and the crew is instructed to turn &lt;em&gt;right&lt;/em&gt; heading 320, then they should perform a 290 degrees turn to the right to meet heading 320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/u0Tto.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/u0Tto.png&quot; alt=&quot;Long turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might not be obvious at first sight as it seems awkward, but it's critical in air traffic control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Notes for the images:&lt;/strong&gt; Compass is set to show &quot;head up&quot; ie the current heading of the aircraft on top and not &quot;north up&quot;. Also the compass rose for brevity does not depict degrees but tens of degrees. So &quot;15&quot; stands for 150 degrees. Images source: own work.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2015-09-20T22:49:02.323" LastActivityDate="2015-09-20T22:49:02.323" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21095" PostTypeId="2" ParentId="21092" CreationDate="2015-09-20T23:05:24.793" Score="15" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;American 755, turn right, heading 320.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aviation phraseology is direct, specific, and concise. The three items here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The controller is instructing the aircraft identified as &lt;code&gt;American 755&lt;/code&gt;&lt;/li&gt;&#xA;&lt;li&gt;to &lt;code&gt;make a right turn&lt;/code&gt; &lt;/li&gt;&#xA;&lt;li&gt;such that they &lt;code&gt;maintain a heading (direction) of 320 degrees (5 degrees north of north-west)&lt;/code&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Though you may not be interested right now, at some level you might have to get technical, as communication involves defining terms :) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case you are interested, for references and further reading &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot;&gt;see this page from the FAA&lt;/a&gt;. Especially of note:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilot/Controller Glossary - contains definitions for radio communications.&lt;/li&gt;&#xA;&lt;li&gt;Aeronautical Information Manual - contains instructions for pilots.&lt;/li&gt;&#xA;&lt;li&gt;JO 7110.65 - (more technical) the handbook for controllers. Everything they say should be in there.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="6886" LastEditDate="2015-09-21T06:07:19.507" LastActivityDate="2015-09-21T06:07:19.507" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21096" PostTypeId="2" ParentId="21081" CreationDate="2015-09-21T01:11:46.213" Score="4" Body="&lt;p&gt;The type of nozzle used in the aircraft depends on the design decisions taken. In short, the designers of F-22 chose stealth over manuverability, while the Sukhoi PAK FA designers went the other way around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Circular thrust vectoring nozzles have been used in Sukoi aircraft for quite some time. The main advantages and disadvantages of the two types of thrust vectoring nozzles are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The circular thrust vectoring nozzles allow control in all the three axes. For example, the PAK FA's engines have a deflection of of 15 (or 16) degrees in pitch axis and 8 in yaw axis, and through differential movement, in roll as well.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/l5Idb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l5Idb.jpg&quot; alt=&quot;Su 35 TVC&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: defencyclopedia.files.wordpress.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 'flat' thrust vectoring nozzles used in F-22 allows control only in the pitch (and roll) axis. However, they do allow higher deflection compared to the axisymmetric nozzles, with the F-119 engine used in F-22 allows deflections upto 20 degrees.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2Imrq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Imrq.jpg&quot; alt=&quot;F 119 Engine thrust vectoring&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: pw.utc.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Another point is that the PAK FA uses a variant of the engine used in Su-30, the AL-41F1. A new engine is still under development. So the final configuration can very well be different, though I doubt it as Russians seem to value maneuverability above stealth.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The main disadvantage of using a axisymmetric nozzle is that it is inherently unstealthy. As far as stealth goes, the circular (or spherical) section is one of the worst design choices. The F-22's nozzle design is optimized for stealth, especially  the edges of the thrust vectoring nozzles are carefully aligned to prevent radar reflection. This is clearly visible in the planform views of the two aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0EdOU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0EdOU.jpg&quot; alt=&quot;PAK FA F-22 Planform Comparison&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://manglermuldoon.blogspot.in&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://manglermuldoon.blogspot.in&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There have been efforts to reduce the RCS of axisymmetric nozzles by incorporating design choices like serrated edges, geometrical shaping (like very low curvature nozzle petals), advanced cooling system, and special coatings on internal and external structures. These were first tested on the F-16 Low Observable Axisymmetric Nozzle (LOAN) program and the resuls were applied to the F-35, another stealth aircraft with thrust vectoring nozzles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n7gsM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n7gsM.jpg&quot; alt=&quot;F-16 LOAN&quot;&gt;&lt;/a&gt;&#xA;Rear view of a standard P&amp;amp;W F-100-200 in F-16 and the LOAN nozzle in the foreground (LMTAS photo), Source: F-16.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, according to ausairpower.net analysis of J-20 which uses an engine similar to PAK-FA, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The tail aspect sector is largely degraded in RCS performance by the use of axi-symmetric nozzles which introduce strong specular and diffraction returns&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In general, a square nozzle provides improved stealth behind and below the aircraft. The F-22 nozzle has serrated shaping similar to that in LOAN nozzles, which further help in reducing RCS.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/daf30.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/daf30.jpg&quot; alt=&quot;Serrated edges in F-22 Nozzle&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://defence.pk&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://defence.pk&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="34686" LastEditDate="2019-08-10T13:26:47.237" LastActivityDate="2019-08-10T13:26:47.237" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21097" PostTypeId="1" AcceptedAnswerId="21107" CreationDate="2015-09-21T03:38:15.997" Score="33" ViewCount="5738" Body="&lt;p&gt;In recent news, &lt;a href=&quot;http://news.sky.com/story/1554989/ba-engine-fire-pilot-criticises-passengers&quot;&gt;the pilot of an aircraft that caught fire&lt;/a&gt; was chastising passengers for taking their luggage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the major concerns behind his criticism? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to put this in context:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;All passengers and crew survived. &lt;/li&gt;&#xA;&lt;li&gt;There were no injuries. &lt;/li&gt;&#xA;&lt;li&gt;Crew reported that the evacuation was very orderly and efficient. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So what could be the reason for the pilot speaking out so critically? So critical, in fact, that he argues that overhead-compartment doors should lock between takeoff and landing. My guesses include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;another passenger cohort could have been less orderly, and pushing with luggage resulted in injuries or people becoming trapped. &lt;/li&gt;&#xA;&lt;li&gt;sliding down &lt;em&gt;inflatable&lt;/em&gt; exit slides with luggage could cause the slides to puncture and trap other passengers. &lt;/li&gt;&#xA;&lt;li&gt;the inflatable exit slides are not rates to carry the weight of an adult + luggage (seems unlikely unless the adult is massively obese). &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Would appreciate hearing a list that is not just educated guessing. &lt;/p&gt;&#xA;" OwnerUserId="57" LastActivityDate="2015-09-23T17:09:05.427" Title="What risks come from passengers taking baggage during emergency evacuation?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;passenger&gt;&lt;evacuation&gt;" AnswerCount="6" CommentCount="11" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21098" PostTypeId="1" AcceptedAnswerId="21105" CreationDate="2015-09-21T07:18:30.170" Score="0" ViewCount="210" Body="&lt;p&gt;Let's say some country intends to introduce a new aviation policy that conflicts with ICAO regulations, like only aircraft certified and approved by our government can fly in our airspace. Can they do that unilaterally? Has it ever happened?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, Russia may declare a country as enemy country and it may use its equipment (e.g reconnaissance aircraft) to spy on this enemy country. In this case enemy country may start defining its own policies and make sure that defense or civil aviation equipment/software are used in compliance with these new policies.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="3775" LastEditDate="2015-09-23T09:09:54.520" LastActivityDate="2015-09-23T13:49:27.957" Title="Can countries introduce new aviation policies unilaterally?" Tags="&lt;regulations&gt;&lt;aircraft-certification&gt;&lt;international&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21099" PostTypeId="2" ParentId="21097" CreationDate="2015-09-21T08:50:36.070" Score="17" Body="&lt;p&gt;Remember the &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airtours_Flight_28M&quot;&gt;Manchester airport fire&lt;/a&gt;... a major fire on the ground which led to the loss of over fifty passengers, partly due to smoke inhalation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These days a fire on board has to be taken very seriously. Just because you're on the ground doesn't mean you're safe!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in your request for a list, there can only be one item on that list... that slowing down the evacuation can result in very heavy losses. I'm sure every commercial pilot has been briefed on past fires and knows how quickly they can become disasters. The fact that no-one received fire related injuries on a particular occasion is irrelevant.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-09-21T08:50:36.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21100" PostTypeId="1" AcceptedAnswerId="21102" CreationDate="2015-09-21T09:20:08.203" Score="13" ViewCount="10770" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KqVcv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KqVcv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do these numbers signify?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can pilots see them while landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do they matter while taking off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do Control Tower mention these while guiding planes on runway?&lt;/p&gt;&#xA;" OwnerUserId="11311" LastEditorUserId="3322" LastEditDate="2015-09-21T13:27:29.943" LastActivityDate="2015-09-21T16:24:25.157" Title="What are the lettered and numbered signs next to airport runways and taxiways?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21101" PostTypeId="2" ParentId="21100" CreationDate="2015-09-21T09:38:31.897" Score="8" Body="&lt;p&gt;Yes they signify &lt;a href=&quot;https://en.wikipedia.org/wiki/Taxiway&quot;&gt;taxiways&lt;/a&gt; (yellow and black markings) and &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway&quot;&gt;runways&lt;/a&gt; (red and white markings)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While landing no, you are too busy to look at taxiway/runway markings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sure they do matter while taking off. Or to be more specific, they matter for taxi and a &lt;em&gt;safe&lt;/em&gt; takeoff. Check out what happened to Singapore Airlines &lt;a href=&quot;https://en.wikipedia.org/wiki/Singapore_Airlines_Flight_006&quot;&gt;flight 006&lt;/a&gt; for not watching the runway markings and taking off from wrong runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When ATC clears a plane for taxi, they mention the taxiways the crew should follow. Though the airport charts have the taxiways marked, they should keep an eye out to make sure they didn't take the wrong turn.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-09-21T09:38:31.897" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21102" PostTypeId="2" ParentId="21100" CreationDate="2015-09-21T10:16:29.057" Score="19" Body="&lt;p&gt;From left to right in your image&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;16 CAT II / III&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Refers to the runway number, and also the &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot;&gt;ILS Category&lt;/a&gt; that particular runway supports. However that is just secondary information. The primary purpose and position of this sign is actually to indicate the hold-short position for the numbered runway.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;E6 34/16&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Refers to the taxiway designation (E6) and the runway(s) it leads to (34/16 being the same runway 34 one way and 16 the other)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;{Unreadable} and E6 L→ 10→&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Both of these signs are the same, one is pretty much unreadable the other is again on taxiway E6 and points that Taxiway Lima (L) is to the right as is runway 10.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pilots are unable to see these signs on landing, signs like this on taxiways are almost exclusively for ground operations - not just the aircraft but the variety of vehicles that operate on the apron of an airfield.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;These signs are equally not useful at the point of takeoff, none of the information presented on them is relevant for that phase of operation.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pilots will have a &quot;map&quot; of an airfield with them which will indicate the same information as presented on these signs. Ground controllers will typically mention which taxiways to use when guiding aircraft (and other vehicles) using the apron and taxiways. For example, at the airfield pictured the ground controllers may have instructed the pilot that they were cleared to &quot;hold short of Runway 10 via Taxiway Echo 6&quot; or may have told a landing aircraft that they should &quot;clear the active runway at Taxiway Lima&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a graphic that many websites use a variation of:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.americanflyers.net/aviationlibrary/pilots_handbook/images/chapter_12_img_11.jpg&quot; alt=&quot;&quot;&gt;&#xA;&lt;sub&gt;Source: &lt;a href=&quot;https://www.americanflyers.net/aviationlibrary/pilots_handbook/chapter_12.htm&quot;&gt;americanflyers.net&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-09-21T16:24:25.157" LastActivityDate="2015-09-21T16:24:25.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21103" PostTypeId="1" AcceptedAnswerId="21104" CreationDate="2015-09-21T10:35:45.747" Score="9" ViewCount="1811" Body="&lt;p&gt;Runway signs show the &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS category&lt;/a&gt; next to the runway designation. But if you flew and didn't drive to the airport, you already know (hopefully). Either way, you are taking off, so you don't really much care. One might say that you will have to land again in case of emergency, but ATC might not give you the same runway. So what's the reason of showing ILS category on runway signs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Note&lt;/strong&gt;: I changed &quot;markings&quot; to &quot;signs&quot; in this question since markings are painted on the ground, signs are the red ones I am asking for.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; The linked question is not exactly the same:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;What is the purpose of several &lt;strong&gt;mandatory stops&lt;/strong&gt; (RWY AHEAD) at busy airports?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are mandatory stops? How are they several? (I never noticed that). I didn't know all these until I asked about the &quot;runway signs&quot;. The other question presumes that you are familiar with some terminology. And it doesn't mention ILS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it looks like a &lt;a href=&quot;https://aviation.meta.stackexchange.com/questions/317/arent-these-two-duplicate/319#319&quot;&gt;similar case&lt;/a&gt;. I vote for reopening.&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="-1" LastEditDate="2017-03-16T15:52:28.310" LastActivityDate="2015-09-22T09:11:50.363" Title="What's the point of having ILS on runway signs?" Tags="&lt;runways&gt;&lt;ils&gt;&lt;airport-markings&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21104" PostTypeId="2" ParentId="21103" CreationDate="2015-09-21T11:10:58.800" Score="15" Body="&lt;p&gt;These markings designate the hold-short point during different runway operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runway hold-short points are marked by white text on a red background. They designate a point which any aircraft must not cross without an explicit clearance from ATC. Note that in the below picture, there are two markings:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xhAIk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xhAIk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cat II or III ILS is used during low visibility operations. In the case of an auto-land, the autopilot literally lands the plane on the runway. To do this, the aircraft systems need a very precise signal from the ILS antenna. Any aircraft on the ground crossing the line of sight between the ILS antenna and the landing aircraft will interfere the signal, sending the landing plane off course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a plane is landing on Cat II or III, other planes on the ground need to stay further back the runway. This has an undesirable side effect - the airport capacity is reduced. If somebody is doing a visual approach on a clear day, you can move a bit closer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=0rn-iI7wX-Y&quot; rel=&quot;noreferrer&quot;&gt;This&lt;/a&gt; is what happened to a Singapore Airlines Boeing 777 when it used auto-land without informing ATC. Since no one is aware they're using auto-land, the standard hold-short procedure (rather than the low visibility procedure) applies. They drifted off the runway pretty much like a racecar!&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-09-21T13:17:19.853" LastActivityDate="2015-09-21T13:17:19.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21105" PostTypeId="2" ParentId="21098" CreationDate="2015-09-21T12:18:14.850" Score="3" Body="&lt;p&gt;Aircrafts need to be certified to operate under FAA/European/Russian... regulations in terms of safety, noise, etc.&#xA;For instance, in Europe &lt;a href=&quot;https://en.wikipedia.org/wiki/European_Aviation_Safety_Agency#Certification&quot; rel=&quot;nofollow&quot; title=&quot;EASA - Certification&quot;&gt;EASA&lt;/a&gt; is the authority &quot;for the airworthiness and environmental certification of all aeronautical products[..]&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes countries actually want to introduce new policies.&#xA;One of the most famous was in 1971, when &quot;The US, India, and Malaysia all ruled out Concorde supersonic flights over the noise concern[..]&quot; as reported here on &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde#Testing&quot; rel=&quot;nofollow&quot; title=&quot;Concorde - Testing&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another one about aircraft noise was in 1999, when &quot;The EU's proposed noise ordinances effectively prevented the use of &lt;a href=&quot;https://en.wikipedia.org/wiki/Hush_kit&quot; rel=&quot;nofollow&quot;&gt;hush-kit&lt;/a&gt; outfitted aircraft in Europe[..]&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So every country already has its own regulation.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="1467" LastEditDate="2015-09-21T15:38:22.830" LastActivityDate="2015-09-21T15:38:22.830" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21106" PostTypeId="2" ParentId="21097" CreationDate="2015-09-21T12:28:16.203" Score="2" Body="&lt;p&gt;As highlighted by these two points of view (&lt;a href=&quot;http://www.airlinereporter.com/2015/09/airline-evacuations-passengers-opinion-taking-bag-not-evil/&quot; rel=&quot;nofollow&quot;&gt;pros&lt;/a&gt; and &lt;a href=&quot;http://www.flightglobal.com/news/articles/opinion-time-to-tackle-baggage-threat-to-aircraft-e-416640/&quot; rel=&quot;nofollow&quot;&gt;cons&lt;/a&gt;), there is no clear answer.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, in case of evacuation, the aircraft must be empty of passengers in less than 90 seconds, not using all exits (because some may be obstructed by fire). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the fact that any luggage in an evacuation process may be lost anywhere from the seat to the tarmac, including the small escape hatches and the middle of the escape slides and cannot be retrieved until the end of the evacuation process, it may constitute a potential obstacle for the other passengers. An obstacle in such a critical phase may lead to at least injuries (broken leg while reaching the end of the escape slide), and in the worst case to passengers not able to evacuate in time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that there are emergency services on the runway, and insurance if you lost luggage in the process. Therefor, the only thing you should think of is to evacuate to stay alive.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="561" LastEditDate="2015-09-23T03:01:38.837" LastActivityDate="2015-09-23T03:01:38.837" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21107" PostTypeId="2" ParentId="21097" CreationDate="2015-09-21T12:32:10.890" Score="58" Body="&lt;p&gt;As soon as there's a fire on board, the absolute top priority is &lt;strong&gt;getting everybody out as soon as possible&lt;/strong&gt;. Aircraft are designed in such a way that, even after a crash landing (or other serious malfunction), the passengers will have a minute or two to evacuate before conditions in the cabin become toxic (fire, smoke, etc); this is done by using flame-retardant material and burn-through protection, but in an intense fire these won't protect the cabin for long, and once they fail no-one will be able to survive inside the aircraft for much longer than that. Smoke inhalation and oxygen deprivation kill just as effectively as being burned. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore everyone has to be able to evacuate from the plane within 90 seconds, even assuming the plane is packed to the gills with passengers, and half the exits are inoperative. Given that the aircraft may be damaged after  a rough/crash landing, some of the doors may be unusable (due to fire or smoke just outside them), it may be dark in the cabin, and people may be injured and/or panicking, it's vital that nothing slows down the evacuation. To get an idea of what a 90-second evacuation of a fully-loaded aircraft looks like, see the video of the &lt;a href=&quot;http://www.youtube.com/watch?v=_gqWeJGwV_U&quot; rel=&quot;nofollow noreferrer&quot;&gt;A380 evacuation test&lt;/a&gt; - and these passengers were calm, uninjured, and prepared. If passengers take hand luggage with them this is slowed down:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The time it takes to get it out of the overhead bins (with everyone else crushing against you to get out).&lt;/li&gt;&#xA;&lt;li&gt;Carrying the luggage down the aisle (without tripping, hurting yourself or anyone else - again, look at the A380 video, and imagine trying to do that with a suitcase). If you lose your luggage, everyone behind you will have to climb over it to get to the exit.&lt;/li&gt;&#xA;&lt;li&gt;Maneuvering your suitcase around the corner to the door, not getting it stuck on the door frame, with people behind you literally shoving you out the door.&lt;/li&gt;&#xA;&lt;li&gt;Plunging down a &lt;em&gt;very&lt;/em&gt; steep slide the height of a two-storey building (or more, in case of the A380's upper deck) at high speed, with your suitcase flailing around. At best it whacks you on the head, at worst it punctures and deflates the slide, which given the crush of passengers behind you will probably lead a few people to plummet from the aircraft doors straight to the ground.&lt;/li&gt;&#xA;&lt;li&gt;Assuming you've made it to the ground, there is someone else plunging down the slide right behind you. If your suitcase slows you down even a little, they will plow right into you, and soon you'll have a crush of people at the foot of the slide.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In this specific case, the fire was fortunately not serious enough to defeat the cabin fire protection before the last passengers had evacuated&lt;/strong&gt; - but as &lt;a href=&quot;https://aviation.stackexchange.com/users/8417/andy&quot;&gt;@Andy&lt;/a&gt; said, there are unfortunately other examples where the passengers were not so lucky. To illustrate the risk of fire after landing: &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_358&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air France Flight 358&lt;/a&gt; ran off the runway at landing, and despite having little fuel on board, the resulting fire completely destroyed the aircraft; luckily, everyone evacuated in time. &lt;strong&gt;Once there's been a major malfunction, there is no way to tell how much time you have left to get out&lt;/strong&gt; - fire can spread very very quickly - and so you have to get out as quickly as possible. Taking luggage with you endangers your life and that of your fellow passengers. &lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-09-21T12:32:10.890" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21108" PostTypeId="2" ParentId="21097" CreationDate="2015-09-21T12:51:44.190" Score="19" Body="&lt;p&gt;Just one angle I would like to add to these excellent answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers might be slow to get off because they want to retrieve their passports, driving licences, phones etc. This could well result in people at the back losing their lives as explained in the other answers on this post.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But consider this: if people are on the aircraft, the fire service can't properly attack the fire, because covering the aircraft with foam might SUFFOCATE the passengers still on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if passengers are quick to get off, the fire service can then deal with the fire as quickly as possible, and it might well result in your driving licence being saved as well, rather than you die along with your driving licence.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-09-22T20:13:32.033" LastActivityDate="2015-09-22T20:13:32.033" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="21109" PostTypeId="2" ParentId="21098" CreationDate="2015-09-21T16:10:54.833" Score="2" Body="&lt;p&gt;Technically, yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of national regulations barring specific aircraft, for example there are several African airlines that may not operate in Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in general there is mutual agreement that other countries' certification agencies are equally capable of assuring the airworthiness of planes, so there is no safety issue here, and the remaining question for a bureaucracy is whether to burden oneself with extra paperwork.&lt;/p&gt;&#xA;" OwnerUserId="3333" LastActivityDate="2015-09-21T16:10:54.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21110" PostTypeId="2" ParentId="21090" CreationDate="2015-09-21T19:45:14.913" Score="4" Body="&lt;p&gt;As the comments have explained, &quot;airside inspection&quot; is tasked with addressing issues &quot;airside,&quot; which means pretty much everything inside the airport perimeter, and outside of the terminals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just about anything airside will affect the safety of aircraft operating at the airport. For this reason, there are generally many regulations and rules that apply to operations here. Airside inspection involves making sure all of these rules and regulations are followed. This can be anything from addressing security issues to removing FOD (foreign object debris) and ensuring markings and signage are in working order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they are responsible for managing activity on the airport apron, they absolutely have the authority to stop anyone that is in the wrong place at the wrong time. Although there may not have been any apparent issue, there could be regulations or dangers that not everyone is aware of. If the flight crew sends passengers out onto the apron when they shouldn't, this is an issue that the airside employees would want to address.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;//agency.governmentjobs.com/portoakland/default.cfm?action=viewclassspec&amp;amp;ClassSpecID=961397&quot; rel=&quot;nofollow&quot;&gt;various&lt;/a&gt; &lt;a href=&quot;//www.corkairport.com/gns/about-us/doing-business-with-us/Airside_Operations.aspx&quot; rel=&quot;nofollow&quot;&gt;descriptions&lt;/a&gt; available for positions that involved airside inspection, including some of the duties involved.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Maintains safety and security on airport premises; ensures TSR 1542 compliance; patrols,inspects, searches and escorts as necessary; conducts identification checks and permits access only to authorized individuals; provides security training as necessary.&lt;/li&gt;&#xA;  &lt;li&gt;Patrols and inspects airport operational areas for potential hazards; ensures compliance with FAR 139 and other federal and local rules; monitors and controls vehicle traffic on taxiways and runways; patrols all airport facilities, airside and landside.&lt;/li&gt;&#xA;  &lt;li&gt;Monitors and controls vehicular traffic on taxiways and runways and public roadways and parking lots; checks for proper ID on vehicles and personnel entering the Airport Air Operations Areas (AOA).&lt;/li&gt;&#xA;  &lt;li&gt;Ensuring compliance with all safety/security regulations and standards within our activities and ground handling operations.&lt;/li&gt;&#xA;  &lt;li&gt;The management of a safe and efficient airside operation by carrying out Airside Inspection Audits and Flight Turnaround Audits. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-09-21T19:45:14.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21111" PostTypeId="2" ParentId="21097" CreationDate="2015-09-21T21:35:56.747" Score="6" Body="&lt;p&gt;If I were in an airplane crash (and when I fly I generally have my young children with me), I wouldn't want people to think that it was OK to stop and take their luggage with them.  First, not only does it slow the evacuation (the goal is get everyone out within 90 seconds), but it puts other people at risk if getting the luggage &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;slows you and the people behind you from getting to the slides, &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;could harm others if you open it and bags coming raining down, &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;could cause an obstruction if it gets caught in the aisles under or in front of someone&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;could damage the slides, and &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;could cause an obstruction at the bottom of the slide as people are coming out of the plane. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the BA flight in LV that caught fire wasn't full.  In an emergency, on a completely full flight, on a larger airplane, do you really want people thinking &quot;those other people on other flights took their luggage and everyone survived!&quot; when you and your loved ones are trying to just get out and get to safety? The pilot of the BA flight has a right to also have strong words, as the flight crew is always the last to evacuate.  Delaying an evacuation could prove particularly harmful to them as they can't get out until everyone else does.  &lt;/p&gt;&#xA;" OwnerUserId="11320" LastEditorUserId="1478" LastEditDate="2015-09-22T07:50:41.553" LastActivityDate="2015-09-22T07:50:41.553" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21112" PostTypeId="1" AcceptedAnswerId="21120" CreationDate="2015-09-21T21:54:27.650" Score="29" ViewCount="19667" Body="&lt;p&gt;When you throw a paper airplane, it flies for a couple of seconds before losing speed and stalling. With a glider, it has a very long wingspan, but you take off with another plane or winch tow pulling it and then it is released on its own. Shouldn't the glider lose all speed and stall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2z82c.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2z82c.jpg&quot; alt=&quot;Glider in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="7611" LastEditDate="2016-01-19T17:48:42.090" LastActivityDate="2019-03-04T03:10:24.007" Title="Why can gliders fly for so long?" Tags="&lt;glider&gt;&lt;theory&gt;" AnswerCount="11" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21113" PostTypeId="1" AcceptedAnswerId="21115" CreationDate="2015-09-21T22:00:28.313" Score="8" ViewCount="724" Body="&lt;p&gt;The whole purpose of an ER model is to increase range and by doing that you need to increase the amount of fuel stored in the wings. EX: Boeing 737-900, Boeing 737-900ER. Is the wing area increased or is their another way to increase fuel capacity.&lt;a href=&quot;https://i.stack.imgur.com/QB2ym.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QB2ym.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:(&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation#/media/File:Lionair_737-900_ER_first_flight.jpg&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation#/media/File:Lionair_737-900_ER_first_flight.jpg&lt;/a&gt;) &lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-22T04:57:19.283" Title="How do ER models store more fuel?" Tags="&lt;range&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21114" PostTypeId="1" AcceptedAnswerId="21130" CreationDate="2015-09-21T22:08:08.497" Score="10" ViewCount="9158" Body="&lt;p&gt;I have noticed that the horizontal stabilizers on some fighter jets move up and down to increase and decrease the angle of attack, but on some airliners they use elevators to adjust the angle of attack. Why isn't this kind of system used on airliners?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="20401" LastEditDate="2018-05-31T15:28:27.133" LastActivityDate="2018-05-31T15:28:27.133" Title="Why do some fighter jets have movable horizontal stabilizer instead of elevators installed on the stabilizers?" Tags="&lt;stability&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="21115" PostTypeId="2" ParentId="21113" CreationDate="2015-09-21T22:09:32.760" Score="15" Body="&lt;p&gt;Not all fuel is stored in the wings. Some is also stored in the fuselage. The ER variants have a larger, or additional, centre (fuselage) tanks at the expense of cargo bays volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The centre tank is located between the wings to minimize the change in centre of gravity as the fuel is consumed. The wing spar, which must go through to provide sufficient structural strength, does not allow the cargo bay to be continuous in most designs anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ER models may be also fitted with more powerful engines to increase the maximum take-off weight (engine out performance is usually the limiting factor), so the plane can still take reasonable amount of payload when the tanks are full.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-09-22T04:57:19.283" LastActivityDate="2015-09-22T04:57:19.283" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21117" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T22:16:19.903" Score="9" Body="&lt;p&gt;In order to keep an aircraft flying, you need to keep adding energy. In an aircraft with an engine, the energy is primarily in the form of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a glider, the additional energy comes from the lifting action of rising air. Glider pilots will find areas of rising air (they have sensitive instruments to assist with this), and circle in that area to increase altitude. Once they have enough altitude, they will fly in a more or less straight line toward their destination, stopping along the way to circle again and gain more altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rising air may come from &quot;thermals&quot; (warm air bubbling up through the atmosphere), &quot;ridge lift&quot; (air rising up a slope), &quot;wave lift&quot; (produced by mountains), and others. You can read more about lift at &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_%28soaring%29&quot;&gt;Lift (soaring)&lt;/a&gt;. There are different flying techniques required to best take advantage of each kind of lift.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-09-21T22:16:19.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21118" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T22:16:55.777" Score="6" Body="&lt;p&gt;You compare 2 different things, the paper plane and the glider. Gliders take weather into advantage to increase their altitude and sustain flight. Paper planes do not experience the same weather phenomena as gliders do. And of course they lack pilot and control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_(soaring)&quot;&gt;Wikipedia&lt;/a&gt; mentions 4 ways to gain energy:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Thermals (where air rises due to heat),&lt;/li&gt;&#xA;  &lt;li&gt;Ridge lift, where air is forced upwards by a slope,&lt;/li&gt;&#xA;  &lt;li&gt;Wave lift, where a mountain produces a standing wave,&lt;/li&gt;&#xA;  &lt;li&gt;Convergence, where two air masses meet&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-09-21T22:16:55.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21119" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T22:17:44.557" Score="5" Body="&lt;p&gt;From the moment the tow or winch is released, a glider starts descending.  If the atmosphere were completely still, apart from trading speed for height, it will soon have to land.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders are designed with very high lift/drag ratios.  40:1, 50:1 even 60:1 or higher.  They stay aloft for long periods because of this and their ability to take advantage of, and the pilots skill in finding, thermals and upward air currents caused by turbulence off ridges, mountains etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paper aircraft have a completely different design (you could not build a glider like the one you show from paper) and &lt;a href=&quot;https://www.youtube.com/watch?v=XHqFDw_94W4&quot;&gt;can fly for a lot longer&lt;/a&gt; than a couple of seconds.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-09-21T22:17:44.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21120" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T22:19:54.350" Score="37" Body="&lt;p&gt;A glider and a paper airplane operate on the same principle: Exchanging whatever potential energy (altitude) they have for the kinetic energy (airspeed) required to keep air moving over the wings so they produce lift, giving a stable, controlled descent (glide).&lt;br&gt;&#xA;In both cases &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed&quot;&gt;the airfoil will not stall unless it exceeds its critical angle of attack&lt;/a&gt; which is independent of the airspeed. You can continue to fly (with the wing not stalled and producing lift) as long as you still have altitude to trade for that airspeed, and if you do it right you will eventually run out of both altitude and airspeed fairly close to the ground, where you can have a soft landing at a speed where the aircraft is not damaged. In the case of a manned glider hopefully this happens on a runway where you can get another tow plane to take you up again.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Both aircraft can extend their glide time by finding &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_(soaring)&quot; rel=&quot;nofollow noreferrer&quot;&gt;other sources of  lift&lt;/a&gt; - thermals, ridge lift, etc. - to carry the vehicle to a higher altitude, providing more potential energy.  Gliders are better at this for one major reason: They have a pilot &lt;a href=&quot;https://www.youtube.com/watch?v=m1tAOmN4ou8&quot; rel=&quot;nofollow noreferrer&quot;&gt;who can keep the aircraft in an area of rising air longer&lt;/a&gt; to gain the most altitude possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A paper aircraft can similarly be made to fly for a longer period of time if given an adequate source of lift (equal to or exceeding its minimum sink rate). There's a rather famous video of the &quot;infinity paper plane&quot; which is a paper airplane circling over an electric stovetop, but I'll spoil it for you and tell you that one is a hoax (the general consensus is the plane was on a string).&lt;br&gt;&#xA;&lt;a href=&quot;https://www.youtube.com/watch?v=Ad1Sjw6bi-k&quot; rel=&quot;nofollow noreferrer&quot;&gt;This one, however, can be replicated fairly easily&lt;/a&gt;: The result is more similar to a helicopter in autorotation or an autogyro in a glide than a traditional fixed-wing glider, but it's a good demonstration of the principles involved.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-21T22:19:54.350" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21121" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T22:52:17.527" Score="2" Body="&lt;p&gt;Basically, the Aerodynamic shape and wing shape along with the power of lift working together to keep the glider up for long periods of time.&lt;/p&gt;&#xA;" OwnerUserId="11321" LastActivityDate="2015-09-21T22:52:17.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21122" PostTypeId="1" AcceptedAnswerId="21127" CreationDate="2015-09-21T22:54:11.793" Score="5" ViewCount="7187" Body="&lt;p&gt;I was reading this article about the &lt;a href=&quot;http://www.gizmag.com/boeing-737-max-final-assembly-winglet/39471/&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737 MAX final assembly&lt;/a&gt; and it was saying something about the new winglet generating lift and increasing efficiency. Can you explain to me how this works, and what other changes to the new winglet are made to make it more efficient?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o2Ces.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o2Ces.jpg&quot; alt=&quot;737 AT Winglets&quot;&gt;&lt;/a&gt;&lt;br&gt;source:&lt;a href=&quot;http://www.gizmag.com/boeing-737-max-final-assembly-winglet/39471/&quot; rel=&quot;noreferrer&quot;&gt;Gizmag&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2015-09-22T03:01:22.787" LastActivityDate="2015-09-22T03:01:22.787" Title="What are some differences that make the new 737 MAX winglets more efficient than a conventional winglet?" Tags="&lt;boeing-737&gt;&lt;winglets&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ClosedDate="2015-09-22T15:18:30.697" ContentLicense="CC BY-SA 3.0" />
  <row Id="21123" PostTypeId="2" ParentId="21114" CreationDate="2015-09-21T22:59:50.437" Score="6" Body="&lt;p&gt;The all movable horizontal tailplane is usually called a &lt;em&gt;stabilator&lt;/em&gt; (stabilizer + elevator) or all moving tail plane or in some cases tail slab. This is mostly used in combat aircraft for a few reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Enhanced Maneuverability.&lt;/strong&gt; The all moving tailplane offers higher maneuverability compared to the stabilizer + elevator found in civil aircraft. Basically, the stabilator gives wider range of pitch control over a larger range of speeds. Also, the stabilator is also hinged about the &lt;em&gt;aerodynamic center&lt;/em&gt;, requiring comparatively lesser control input from the pilot for operation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vYeJC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vYeJC.jpg&quot; alt=&quot;F 22 Raptor Tail plane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F_22_Raptor_Tail_Feathers_photo_D_Ramey_Logan.jpg#/media/File:F_22_Raptor_Tail_Feathers_photo_D_Ramey_Logan.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;F 22 Raptor Tail Feathers photo D Ramey Logan&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:WPPilot&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:WPPilot&quot;&gt;WPPilot&lt;/a&gt; - Own work. Licensed under CC BY-SA 4.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Weight and Drag.&lt;/strong&gt; The stabilator construction is simple compared to the stabilizer + elevator, having practically only a plate, and having no control linkages inside. This makes it lighter and produces lesser drag.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Stability.&lt;/strong&gt; The stabilator design helps in eliminating the Mach tuck. Mach tuck is nose down tendency due to a change in the position of the centre of pressure. This is caused by a rearward movement of the shock wave which occurs in an aircraft in transonic flight. As the aircraft accelerates beyond its limiting Mach number or critical Mach number (the maximum Mach number it can operate), the elevator authority required to control the aircraft (to prevent a dive) increases beyond that of the elevator. The stabilator design prevents this.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Stealth.&lt;/strong&gt; The stabilator design, with its clean lines and no discontinuities, offers more stealth compared to the stabilizer and elevator design. The design can also be optimised for stealth with edges etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some GA aircraft do use all moving tail planes for e.g. &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper Cherokee&lt;/a&gt;. However, there are a couple of reasons this system is not usually used in civil aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Control Power.&lt;/strong&gt; As already noted, the stabilator is hinged about the aerodynamic center, which means that the moment (and the pilot power) required is constant. In case of civil aircraft, the airplane must show an increasing resistance to an increasing pilot input. When they are used, the stabilators in GA aircraft have an anti-servo tab to provide more resistance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Axsea.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Axsea.jpg&quot; alt=&quot;Piper Cherokee Stabilator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: avstop.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Requirements.&lt;/strong&gt; There is no requirement in civil aircrafts for higher maneuverability or supersonic flight. In case of Concorde, the trim problem in transonic range was overcome by shifting fuel between the fuel tanks, thereby changing the center of gravity of the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="20401" LastEditDate="2018-05-31T15:14:21.877" LastActivityDate="2018-05-31T15:14:21.877" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21124" PostTypeId="2" ParentId="21112" CreationDate="2015-09-21T23:34:49.303" Score="9" Body="&lt;p&gt;The glider and a paper aircraft are designed and operated in different ways which affects their stalling characteristics. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Both aircraft trade one form of energy (potential energy or altitude) in order to gain another (Kinetic energy or forward speed). In general, the gliders are in (a controlled) descent unless they encounter thermals or rising air. This is what causes their gliding. The same happens with any unpowered aircraft; however, the gliders have a lot of altitude to expend compared to the paper aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The gliders are designed to be highly aerodynamically efficient, with extremely high lift to drag ratios, usual in the range of 50:1 or more. That means that they can glide for extremely long distances, left to their own devices. The paper airplanes are not like this. However, with proper design, they can be made to fly longer.&lt;/li&gt;&#xA;&lt;li&gt;The gliders are usually flown by (skilled) pilots, who know how to find and make use of the aforementioned thermals, upward air currents etc, which helps in increasing altitude and keeping the aircraft in air longer.&lt;/li&gt;&#xA;&lt;li&gt;Most of the gliders are extremely stable compared to the paper aircraft (which usually has only a wing and no stabilizer), which prevents them from stalling when left alone. In fact, in some gliders, the best way to recover control is to let go of the controls. It basically means that the glider returns to level flight when no control inputs are given.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9716" LastEditDate="2015-09-21T23:43:21.993" LastActivityDate="2015-09-21T23:43:21.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21125" PostTypeId="1" CreationDate="2015-09-21T23:54:12.633" Score="12" ViewCount="844" Body="&lt;p&gt;Can a US president use a personally owned jet with the call sign AF1? Would the Air Force be obligated to add security and defense measure to this aircraft if the president refused to fly in the VC-25?&lt;/p&gt;&#xA;" OwnerUserId="6998" LastEditorUserId="14897" LastEditDate="2019-04-06T12:07:26.733" LastActivityDate="2019-04-06T12:07:26.733" Title="Can a U.S. President have a non-government owned aircraft that would routinely be given the call sign AF1?" Tags="&lt;military&gt;&lt;usa&gt;&lt;call-sign&gt;&lt;head-of-state-transport&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21126" PostTypeId="2" ParentId="21125" CreationDate="2015-09-22T00:15:15.350" Score="17" Body="&lt;p&gt;Air Force One is the &lt;em&gt;call sign&lt;/em&gt; of whatever USAF aircraft (see @slookabill's comment below) the US President travels in. Once he boards another aircraft, the call sign AF1 is transferred to that aircraft (for a dramatic example of this, see the climax of &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Force_One_%28film%29&quot;&gt;Air Force One&lt;/a&gt; movie).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a president were to fly in their own aircraft (or commercially) the appropriate ATC call sign would be &lt;a href=&quot;https://en.wikipedia.org/wiki/Executive_One&quot;&gt;&lt;em&gt;Executive One&lt;/em&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as fitting out a personal aircraft, the VC-25s are USAF assets (operated by 89 AW) and are highly customised and specifically configured for the job of transporting the president (and support staff), costing over $300 million. I doubt any president is going to get the option of flying their favorite aircraft on a regular basis instead of the state aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not likely that the government would pay to configure another (non-USAF) aircraft for the president to the same specifications as the VC-25s serving as Air Force One. After all no US President's personal car has been configured as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Presidential_state_car_%28United_States%29&quot;&gt;Presidential State Car&lt;/a&gt; so far.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="64" LastEditDate="2015-09-22T05:28:30.447" LastActivityDate="2015-09-22T05:28:30.447" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21127" PostTypeId="2" ParentId="21122" CreationDate="2015-09-22T02:15:17.830" Score="4" Body="&lt;p&gt;The 737 MAX winglet is the latest develpment in the 'winglet war' going in between the Boeing and Airbus. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it has been described how winglets work and its advantages, I will not go into those. Most of the wingtip devices in use today are there simply to reduce the effect of wingtip vortices i.e. they are more or less vertical to the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the 737-200 winglets produce little lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XQJ01.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XQJ01.jpg&quot; alt=&quot;737-200 winglet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: .b737.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same goes for 737-800 variants, which use blended winglets which do produce a little lift (redistributing the spanwwise loading).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fwGUU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fwGUU.jpg&quot; alt=&quot;737-800 winglet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A_Garuda_Indonesia_Winglets_Boeing_737-800_NG.JPG#/media/File:A_Garuda_Indonesia_Winglets_Boeing_737-800_NG.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;A Garuda Indonesia Winglets Boeing 737-800 NG&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:FathirLeone&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:FathirLeone&quot;&gt;FathirLeone&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And also the 737 NG 'Split Scimitar' wingtips (where do they get these names?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gURVh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gURVh.jpg&quot; alt=&quot;737 NG Split Scimitar Winglet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This adds some weight to the aircraft. For example, the 737 winglet weighs arounf 180 lbs and the total structutal weight increase due to it is around 480 lbs. Obviously, the winglets more than compensate for this increase, that's why we see them used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With modificaitons, the wintip devices can be used to produce lift and this is the path being taken today with new wingtip device designs, especially with the blended winglet. Boeing took this to the extreme in 787 raked wingtips, which is basically in the horizontal plane, which increased the actual aspect ratio of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sq3Eg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sq3Eg.jpg&quot; alt=&quot;787 raked wingtip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: malaysianwings.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another idea is to use them to generate lift by changing their angle of installation. This makes the 737 MAX winglet somewhere in between the legacy 737 and 787 winglets. The 737 MAX Advanced Technilogt (AT) winglet has two parts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An upper part which is at an angle, resulting in some lift being produced.&lt;/li&gt;&#xA;&lt;li&gt;A lower strake.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The idea is that the winglets also produce some lift in addition to drag reduction. According to Boeing,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The AT winglet further redistributes the spanwise loading, increasing the effective span of the wing. The AT winglet balances the effective span increase uniquely between the upper and lower parts and therefore generates more lift and reduces drag. This makes the system more efficient without adding more weight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AT winglets distribute spanwise loading like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZhTlL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZhTlL.jpg&quot; alt=&quot;AT winglets spanwise loading&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: b737.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: the first one is the baseline aircraft with no winglet. The second one has the 'blended' winglet, while the third one gives the AT winglet. As can be seen above, some of the lift is generated by the winglets itself.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-22T02:15:17.830" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21128" PostTypeId="1" AcceptedAnswerId="21141" CreationDate="2015-09-22T05:35:28.393" Score="5" ViewCount="1474" Body="&lt;p&gt;As science and engineering keep inventing new technologies like flying cars &lt;a href=&quot;http://www.iflscience.com/technology/are-flying-cars-finally-becoming-reality&quot; rel=&quot;nofollow&quot;&gt;http://www.iflscience.com/technology/are-flying-cars-finally-becoming-reality&lt;/a&gt;, air space may become heavily overcrowded. Will flying cars be considered &quot;aviation&quot; or are there (will there be) some rules like flying with particular altitude will be considered as aviation? (As the concept is becoming reality soon or later it has to be decided.)&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="5517" LastEditDate="2015-09-29T15:01:22.313" LastActivityDate="2015-09-30T09:15:36.417" Title="Will flying cars fall under aviation regulations?" Tags="&lt;air-traffic-control&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21130" PostTypeId="2" ParentId="21114" CreationDate="2015-09-22T06:43:08.517" Score="17" Body="&lt;p&gt;All parts of an airliner's horizontal surface move, not just the rear part. The rear part, called an elevator, can move much faster and is for maneuvering. The forward part, called a (trimmable) stabilizer, is for trimming and moves slowly. It is moved in response to changes in loading, speed or flap settings and positions the tail surface such that only small continuous elevator deflections are needed. It doesn't need to move fast - high load factors would upset the passengers and overload the structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DDUVM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DDUVM.jpg&quot; alt=&quot;A330 port tailplane root&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A330 port tailplane root (picture &lt;a href=&quot;http://www.airlinercafe.com/Walkarounds/a333/Tailplane%20root%20Port.JPG&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the markings which show the range of incidence angles covered by the trimmable stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Benefits of a stabilizer-elevator configuration:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Camber: The elevator deflection changes the camber of the airfoil of the tail surface and makes the production of the intended lift change &lt;strong&gt;more efficient&lt;/strong&gt;. If the elevator deflection is supposed to create a downforce, negative camber is produced and vice versa. This &lt;strong&gt;reduces&lt;/strong&gt; the drag which is created in order to maneuver the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Lower control forces: By moving a smaller surface, &lt;strong&gt;less&lt;/strong&gt; hydraulics power, and on small aircraft, &lt;strong&gt;less&lt;/strong&gt; muscle power is needed for the same moment change than with a full-flying tail or all-moving surface. Makes sense, right?&lt;/li&gt;&#xA;&lt;li&gt;Better tailoring of the hinge moment derivatives: Two effects are important for getting the control forces right: The change in hinge moment over deflection angle ($c_{r\eta}$), and the change in hinge moment over angle of attack ($c_{r\alpha}$). With tabs, the right elevator hinge position, nose shape and control horns, both can be tailored individually, while a full-flying tail or all-moving surface will give the designer less freedom to manipulate both independently. Note that full-flying tails only emerged with hydraulic controls, because only those systems can manage the control forces of all-moving control surfaces at high speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/42Dgv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/42Dgv.jpg&quot; alt=&quot;Balance and hinge line position&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horn balance and overhang balance on control surfaces (picture &lt;a href=&quot;http://www.pilotfriend.com/training/flight_training/fxd_wing/images2/56.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Benefits of a full-flying tail surface&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;By avoiding a contour break due to a flap deflection, all-moving control surfaces can avoid the shocks which would otherwise occur &lt;strong&gt;at high subsonic speed&lt;/strong&gt;. This is their main benefit for combat aircraft.&lt;/li&gt;&#xA;&lt;li&gt;At supersonic speed, the uncambered surface will produce less drag, so for supersonic speed the all-moving control surface is more efficient.&lt;/li&gt;&#xA;&lt;li&gt;By moving all of the tail surface at high speed, an all-moving control surface will produce the highest rate of moment change over time possible. To produce also the highest sustained moment change, however, it needs to be larger than a comparable stabilizer-elevator combination because it forfeits the benefits of variable camber.&lt;/li&gt;&#xA;&lt;li&gt;The all-moving control surface has no gaps which could add radar reflections, allowing for a more stealthy design.&lt;/li&gt;&#xA;&lt;li&gt;Lower mechanical complexity. This is somewhat offset by the need for much beefier hydraulics.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-04-06T15:50:29.973" LastActivityDate="2016-04-06T15:50:29.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21131" PostTypeId="1" AcceptedAnswerId="21132" CreationDate="2015-09-22T06:43:11.783" Score="2" ViewCount="646" Body="&lt;p&gt;what are the different ways to avoid skidding off the runway apart from thrust reversers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do crew have any option if thrust reversers are not available and the ground is too slippery which is making the vessel skids off the runways sideways?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2016-06-14T16:57:30.743" LastActivityDate="2016-06-14T16:57:30.743" Title="what are the ways to avoid skidding off the runway apart from thrust reversers?" Tags="&lt;braking&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ClosedDate="2015-09-22T19:54:47.880" ContentLicense="CC BY-SA 3.0" />
  <row Id="21132" PostTypeId="2" ParentId="21131" CreationDate="2015-09-22T07:54:32.140" Score="9" Body="&lt;p&gt;Your question appears to assume that thrust reversers are an acceptable way of keeping an aircraft from sliding off a slippery runway. While this may be true in rare cases, generally speaking you would NOT want to use reverse thrust to avoid skidding off a runway as that typically would exacerbate the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the following scenario: you have an icy runway and a strong crosswind from the right. As you start the takeoff roll, the airplane begins drifting left. You apply right rudder to correct, and the aircraft heading moves to the right of the runway direction. If you resolve the engines thrust vector into it's components relative to the runway centerline, you have most of the thrust propelling you down the runway, a much lesser amount propelling you toward the right side of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets say the left drift continues in spite of the engine thrust vector driving the aircraft to the right side of the runway, and you decide to abort the takeoff using reverse thrust. Thus, the thrust vector relative to the runway centerline will slow the aircraft. However the thrust vector 90&amp;deg; to the runway centerline will be toward the left side of the runway, which when added to your leftward drift will likely put you off the left side of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you Google &quot;tower air 747 crash&quot; you'll see a number of entries concerning just such a scenario and the result. I found &lt;a href=&quot;http://flightsafety.org/ap/ap_mar97.pdf&quot;&gt;http://flightsafety.org/ap/ap_mar97.pdf&lt;/a&gt; to be the most instructive, although I do not wholly agree with the conclusions or with the narrative of what happened (a friend of mine was in the jumpseat right behind the captain, and I flew as a f.o. with that captain).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An obvious answer to your question is to never get yourself into such a serious situation. Can you wait for better conditions? Is another runway available? But if you MUST use a slippery runway for either takeoff or landing (or have already foolishly committed yourself), remember that if a runway is that slippery, it's feasible to continue down the runway in a manner that your course (the runway direction) doesn't match your heading. If the captain of the Tower Air flight had elected to do that, he might not have had the accident he did, or he might have had a much more serious accident. Tough call!&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-09-22T07:54:32.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21133" PostTypeId="1" CreationDate="2015-09-22T08:12:50.877" Score="19" ViewCount="18025" Body="&lt;p&gt;Reading about 737-900ER take off roll (3000 meters) from another question, I would like to know what this means.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it intended that the aircraft needs 3000 meters before it can pitch up to take off or at 3000 meters is has acquired sufficient height and should be airborne?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-09-22T20:58:03.383" Title="What is a take off roll?" Tags="&lt;takeoff&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21134" PostTypeId="2" ParentId="21133" CreationDate="2015-09-22T08:39:17.883" Score="7" Body="&lt;p&gt;Take Off Roll is &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.629_Takeoff_Roll.pdf&quot;&gt;defined&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The process whereby an aircraft is aligned with the runway centerline and the aircraft is moving forward with the intent to take off. For helicopters, this pertains to the act of becoming airborne after departing a takeoff area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-09-22T08:39:17.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21135" PostTypeId="2" ParentId="21133" CreationDate="2015-09-22T09:11:13.660" Score="19" Body="&lt;p&gt;The take-off roll, also called ground roll, is the roll distance before the aircraft becomes airborne. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the 737-900ER, it will be in the order of 2000 meter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quoted 3000 meter is probably the take-off distance required (TODR) or take-off run required (TORR) at maximum take off weight. That assumes a full throttle acceleration to about half of the runway (1500 m), then an engine failure, continued acceleration on a single engine, rotation and take-off at 3000m. In case of TODR, the climb to a height of 35 ft is included as well (for FAR Part 23 aircraft it is 50 ft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means the 737-900ER requires a runway of 3000 meter length to take-off with an engine failure or to stop when the failure happens before the decision speed (V&lt;sub&gt;1&lt;/sub&gt;). Since engine failures are unpredictable this is the minimum runway length required for take-off planning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all assumes ICAO standard atmosphere conditions. For runways at higher altitude ( &gt; MSL) / higher temperature (&gt; 15 deg C) the TORR will be even higher.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-22T20:58:03.383" LastActivityDate="2015-09-22T20:58:03.383" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21136" PostTypeId="2" ParentId="21112" CreationDate="2015-09-22T10:08:15.360" Score="2" Body="&lt;p&gt;One way or another, a flying object has to push down on the air to keep flying.  Given that air is fluid, we have to make the change in momentum of the air at least as big as the weight of the aircraft. Now:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;force = difference in (mass * velocity)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;But the change in energy required to do this alone goes as&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;change in energy = change in (mass * velocity &lt;em&gt;squared&lt;/em&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So for efficient flight, we want to push down on a large mass of air with a small change in vertical velocity, rather than a small mass of air with a large velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders, with their long skinny wings, are optimized to do this: they fly relatively slowly intercepting a relatively large mass of air and pushing down on it gently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the other extreme, vertical take-off jets, like the Harrier, have to take the opposite approach. They need to fly fast, so in hover they push down a relatively small mass of air very quickly.  This is horribly inefficient so a Harrier can not hover for very long before its fuel is exhausted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to this, a glider is relatively light as it does not have to carry fuel or an engine.  It also is made a smooth an slippery as possible to reduce air resistance.&lt;/p&gt;&#xA;" OwnerUserId="11327" LastEditorUserId="-1" LastEditDate="2015-09-22T11:53:27.070" LastActivityDate="2015-09-22T11:53:27.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21137" PostTypeId="2" ParentId="21131" CreationDate="2015-09-22T12:15:55.117" Score="0" Body="&lt;p&gt;The aerodynamic controls (ailerons, elevators and mainly the rudder for this question) still have an effect when the aircraft is on the ground but is still at speed. So even if the plane slides or aquaplanes a little bit at high speed it is generally controllable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is at lower speeds when these controls don't work as well / at all. You could be in a situation where the aerodynamic controls don't work and you are going to fast for the wheels to grip, or even you are stopped and a crosswind blows you sideways off the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the wind is down the runway hopefully you can get down, but taxying might be another matter. Possibly there are reduced cross wind limits on icy runways... I don't know I only fly light aircraft and generally not in those conditions.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-09-22T12:15:55.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21138" PostTypeId="1" CreationDate="2015-09-22T13:21:00.807" Score="5" ViewCount="3145" Body="&lt;p&gt;Is it possible to convert McDonnell Douglas/BAe Systems AV-8B Harrier II Plus into an effective and usable supersonic aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;May be, by changing the engine or applying some modifications on the air-frame...&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="9656" LastEditDate="2015-09-22T14:17:18.553" LastActivityDate="2020-09-30T12:23:37.673" Title="Is it possible to modify an AV-8B Harrier II to a supersonic aircraft by applying some modification?" Tags="&lt;airspeed&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21139" PostTypeId="2" ParentId="21138" CreationDate="2015-09-22T14:17:05.400" Score="10" Body="&lt;p&gt;There was actually a plan to convert the Harrier into a supersonic aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The original plan that lead to the development of the Harrier actually had a supersonic variant, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_P.1154&quot; rel=&quot;noreferrer&quot;&gt;Hawker Siddeley P.1154&lt;/a&gt;. The P.1154 was supposed to be a supersonic aircraft using the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bristol_Siddeley_BS100&quot; rel=&quot;noreferrer&quot;&gt;Bristol Siddeley BS100&lt;/a&gt; engine, which used Plenum Chamber Burning(PCB).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the BS100 engine, cold bypass and hot core turbine airflows are split between two sets of nozzles, front and rear, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Pegasus&quot; rel=&quot;noreferrer&quot;&gt;Rolls Royce Pegasus&lt;/a&gt; engine which powered the Harrier. The PCB called for additional fuel and afterburning applied to the front cold air nozzles only, increasing thrust. The PCB increased the thrust from 116 kN to 160 kN.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6Ursj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Ursj.jpg&quot; alt=&quot;Plenum Chamber Burning&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: aeromodelbasic.blogspot.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the P.1154 never saw the light of the day due to various reasons and the subsonic Hawker P.1127 was developed into the AV-8 Harrier. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, Hawker and McDonnel Douglas joined to develop the AV-16 concept, basically a plan to double the range and payload of the Harrier. One version of the AV-16 called for supersonic flight too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some modifications that were considered in the study for supersonic aircraft were,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A more powerful engine (called Pegasus 15) which used PCB&lt;/li&gt;&#xA;&lt;li&gt;A bigger fuselage for the bigger engine&lt;/li&gt;&#xA;&lt;li&gt;A larger 'supercritical' wing&lt;/li&gt;&#xA;&lt;li&gt;A lengthier, more slender fuselage&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This version was called HS.1185, as shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KJPsC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KJPsC.jpg&quot; alt=&quot;AV 16&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: harrier.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in March 1975, Hawker pulled out due to budget cuts and other reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, Rolls Royce (ground) tested Plenum Chamber Burning in the Pegasus engine and made some progress in the 1980s. This was supposed to be used in yet another (supersonic) variant of Harrier. One of the versions was the HS. 1205, which had redsigned F-16 type inlets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PPMwv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PPMwv.jpg&quot; alt=&quot;HS 1025&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: harrier.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this also came to nothing and the project was shelved. For a full list, see &lt;a href=&quot;http://www.harrier.org.uk/history/projects.htm&quot; rel=&quot;noreferrer&quot;&gt;Harrier site&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question, it would be possible to make the Harrier go supersonic using more powerful engines and modifications to airframe (listed above).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-22T14:17:05.400" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21140" PostTypeId="2" ParentId="14567" CreationDate="2015-09-22T14:30:58.067" Score="7" Body="&lt;p&gt;From &lt;a href=&quot;https://www.iata.org/contentassets/04c5400c2dcd4b05a520330672b13ef6/iata-passenger-glossary-of-terms.xlsx&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA passenger glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;Leg:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The operation between a departure station and the next arrival&#xA;station.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Segment:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A leg or a group of legs from boarding point of a passenger to a&#xA;deplaning point on a given flight.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sometimes referred to as &amp;quot;City Pair&amp;quot;.  The operation between board&#xA;point and any subsequent off point within the same flight number.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Leg vs Segment in layman terms:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A leg stops when the plane lands.&lt;/li&gt;&#xA;&lt;li&gt;A segment stops either when you change flight number of when you&#xA;arrive at one city where you want to spend time.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;One segment includes one or more legs from the same flight number. Sometimes a plane lands to refuel or to load other passengers but is technically the same flight number. Every ticket's coupon represent a segment.&lt;/p&gt;&#xA;&lt;p&gt;It is the first time I have heard the slice term.&lt;/p&gt;&#xA;" OwnerUserId="1019" LastEditorUserId="1019" LastEditDate="2020-09-21T21:20:43.587" LastActivityDate="2020-09-21T21:20:43.587" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="21141" PostTypeId="2" ParentId="21128" CreationDate="2015-09-22T14:39:59.257" Score="6" Body="&lt;p&gt;Flying cars will need to be regulated by both the FAA and the DOT as per current laws here in the US. For what its worth flying cars are really more like road capable airplanes. When the car is airborne it will be subject to the regulations set fourth by the FAA for the airspaces it passes through and maneuvers it makes. When the car is on the road it will be subject to vehicular laws that any other car would see. That being said there is room for change here and who knows what rules may be passed in the future. There is also some grey area around things like landing in a parking lot, folding up your wings and driving away as well as the reverse case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rules that currently govern aviation are more than capable of handling flying cars, even if they start taking off from peoples driveways. The larger issue is licensing the pilots. A drivers license is pretty easy to come by here in the states while a PPL or sport pilots license takes quite a bit of time. Everyone that currently would want a flying car would need both a drivers license and a pilots license of some form. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know the FAA makes the rules for any and all altitudes. While some airspaces (class G) may be unregulated they are still considered from the ground up. There is no minimum altitude at which FAA regulations don't apply and its far from a free for all in the skys the way it is on the roads in a manner of speaking. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying cars could potentially cause an increase in air traffic however the advantage of a plane (over driving) is generally speed. Until someone can build a car that can do 80MPH consistently on the road and a formidable 130Kts (and thats the slow end of planes) through the air the use case is pretty small. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the biggest preventers in the whole flying car situation is the engine its self. Car engines fit quite a different role than aircraft engines. The similarities end basically at the fact they are both piston engines. Some car engines have been put in planes (Mooney/Porsche PFM 3200) and in the end they are generally not great planes. You can find a &lt;a href=&quot;https://aviation.stackexchange.com/questions/11527/what-are-some-of-the-differences-between-piston-engines-used-in-aircraft-and-aut&quot;&gt;full discussion on this here&lt;/a&gt;. You also need to keep in mind that anyone who will be fixing these vehicles will need to be an A&amp;amp;P licensed mechanic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few companies with some cool animations of future products and even a few test rigs that have been built but to date the engineering is just not really there. Chances are it will be &lt;a href=&quot;http://www.digitaltrends.com/cars/hang-onto-your-honda-why-the-terrafugia-transition-wont-make-flying-cars-mainstream/&quot; rel=&quot;nofollow noreferrer&quot;&gt;some time before flying cars are even on the road&lt;/a&gt; let alone creating major air traffic issues. For the 279,000 a Terrafugia will cost you, you could buy a Used Piper Arrow (in great shape) and a Porsche and still have 79,000 left over for a hanger to keep them in...      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-09-22T18:03:08.753" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21142" PostTypeId="2" ParentId="21112" CreationDate="2015-09-22T16:29:36.930" Score="1" Body="&lt;p&gt;Other people have already mentioned the use of weather to keep the glider afloat longer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think you are asking, &quot;How do wings work?&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft wings are modeled after what we have seen in nature. The basic shape is the wing is flat on the bottom and curved on the top. This curve is similar to a curve found on part of an egg with the bulk of the width located in front of the wing. (You can google up more optimized shapes.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Forward motion will compress the air above the leading portion of the wing but will also create some drag in the process. The following portion of the wing slowly thins to the trailing edge. This portion of the wing is the area that has the negative air space (lift). It is this negative space that all aircraft rely on. Helicopter blades and engine propellers also make use of this basic shape. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A gliders initial propulsion is a tow, but after that they rely on gravity for propulsion and the lift created by the wing shape, in addition to weather assists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparatively, [without using specialized measurement tools or going into a higher math explanation, the flatness of] a paper airplane has [only negligible] lift [when comparing to an optimized man made wing or wing found in nature] and relies solely on you for a one time propulsion [unless you are lucky enough to find an exhaust grate or the like to fly over]. &lt;/p&gt;&#xA;" OwnerUserId="11337" LastEditorUserId="11337" LastEditDate="2015-09-22T21:13:31.777" LastActivityDate="2015-09-22T21:13:31.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21143" PostTypeId="2" ParentId="21112" CreationDate="2015-09-22T16:35:45.460" Score="16" Body="&lt;p&gt;The primary difference between a glider and a paper airplane is that most folded paper airplanes have very bad aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most folded paper airplanes have short stubby wings. This in itself makes it very draggy. The ideal wing with absolute minimum drag has a wingspan of infinity. Obviously it's not possible to build that ideal wing (we don't have infinite number of atoms in the universe). But generally, all else being equal, the longer the wingspan the less the drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, paper airplanes have very poor airfoils compared to real gliders. They're not even flat plates (which would actually be a fairly good airfoil at the Reynolds Number they fly). The folds typically add uneven thickness to the airfoil making it a bit wedge shaped. This adds a lot of drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, you mention that the paper airplanes you're used to flying tend to lose speed and stall. Stalling definitely reduces glide time. Stalling wastes energy. A smooth glide will tend to stay aloft longer. A real glider is trimmed to glide smoothly and not stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Toy gliders need not suffer the weaknesses of paper airplanes. A good toy glider should be able to fly for at least 10 seconds per flight on average (or at least 3 seconds if you throw it level instead of up). Really well designed toy gliders can fly for more than 20 seconds and competition gliders should be able to fly for around 1 minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you've never seen a balsa glider fly before you'd think that it's flying for a very long time. Here's one example (it was the video that introduced me to hand-launched gliders): &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/zYzXhgI1RaI?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;. And here's a more recent example: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/TOT4WwDrONA?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The world record for hand-launched gliders is almost 2 minutes: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/a7S08d99UZI?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These gliders fly longer than the typical paper airplane because they're well designed and are aerodynamically more efficient. Note that most of these balsa gliders (including the world record glider) have eyeballed, imperfect airfoils. Sometimes they're even triangular or just have the leading and trailing edges beveled. So the airfoil is not as important as the design, trim and balance (CG) of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paper airplanes need not suck. Here's a clip of the world record (duration) flight of a paper airplane: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/YBQezzTovZY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;. If you google around for the design of that plane you'll find that it has a lot of nose weight (good balance/CG) and bent up trailing edges (good trim).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the key lessons are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Balance your plane (adjust the CG). This is true for paper airplanes, RC planes and even real airplanes of all sizes. Bad CG is the number one reason planes stall. There are formulas and rules of thumb to calculate the correct CG for your plane but for a paper airplane I'd suggest just experimenting with adding and removing nose weight (that's what people do with balsa gliders).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduce drag. For paper airplanes you can try creasing the fold better so that the folded part is as thin as possible. Gliders can increase wingspan and choose low drag airfoils to reduce drag but that's not quite applicable to paper airplanes. Then again, there are paper gliders that have relatively long wingspans (compared to typical paper airplanes) that can glide very well: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/ko7beLCkScQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;. But that's entering into the scissors and tape category.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-09-22T16:35:45.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21144" PostTypeId="2" ParentId="19609" CreationDate="2015-09-22T16:48:52.923" Score="10" Body="&lt;p&gt;The main advantage of diesel-electric is that it offers &lt;a href=&quot;https://www.physicsforums.com/threads/why-do-electric-motors-have-high-torque.388750/&quot;&gt;a great deal of torque at low motor rpm&lt;/a&gt; [from Physics Forums]. In effect, the torque curve of an electric motor is &lt;em&gt;highest&lt;/em&gt; at 0 rpm, and has a very flat decrease as rpms increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is of great value for vehicles that have to pull a great deal of weight, and to overcome the inertia of moving it from a standing start. It is of little or negative value for aircraft because it is much less efficient. Anytime you generate power from one medium and then use that power to drive another medium, a lot of power is wasted. So converting diesel oil to mechanical energy, then further converting it to electrical energy, is far too wasteful and unnecessary for a helicopter, where every erg counts. With helicopters, which these days mainly use gas turbine engines, as much of the power as possible gained by burning fuel is converted directly into rotary motion. Note also that massive torque at low rpm is useless for rotor aircraft, since it is only at high rpm that such craft are able to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Important, too, is the fact that dual-power systems like diesel-electric add a lot of weight, since you are dealing with two different types of engine. For any aircraft, especially the helicopter, that may even be a bigger drawback than wasted energy—though these things may be viewed as two sides of the same coin.&lt;/p&gt;&#xA;" OwnerUserId="11336" LastEditorUserId="11336" LastEditDate="2015-09-22T17:01:00.447" LastActivityDate="2015-09-22T17:01:00.447" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21145" PostTypeId="1" AcceptedAnswerId="21149" CreationDate="2015-09-22T17:51:03.300" Score="5" ViewCount="951" Body="&lt;p&gt;In cases such as a low altitude stall the quick application of power might get a pilot out of a sticky situation, but turbofan engines are fairly sluggish in increasing thrust. If throttle is applied to quickly it can even cause a surge. I'm assuming the problem is the inertia of the fan and compressor. What things do engine manufacturers do to make the engines more responsive? What are the tradeoffs? Do other types of engine (turboprop, turbojet, etc.) suffer from the same problem of delayed response?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2015-09-22T20:06:20.370" LastActivityDate="2015-09-23T06:50:05.380" Title="What methods are used to make a turbofan engine spool up quicker?" Tags="&lt;turbofan&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-09-23T09:16:36.240" ContentLicense="CC BY-SA 3.0" />
  <row Id="21146" PostTypeId="2" ParentId="21133" CreationDate="2015-09-22T18:23:19.513" Score="-1" Body="&lt;p&gt;737's typically take off in 3000 to 4000 feet depending on cargo and configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TORR and other statistics are runway length guidance figures that are much longer than the actual distance the aircraft rolls before it leaves the ground.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-09-22T18:23:19.513" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21147" PostTypeId="2" ParentId="21131" CreationDate="2015-09-22T19:01:30.857" Score="0" Body="&lt;p&gt;Thrust reversers are not used to steer an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground the rudder is used to steer during landing and takeoff. The main wheel brakes can be used to make tight turns when taxing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-09-22T19:01:30.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21148" PostTypeId="1" AcceptedAnswerId="21152" CreationDate="2015-09-22T19:13:04.827" Score="26" ViewCount="955" Body="&lt;p&gt;Most aprons of international airports are vast areas paved with asphalt or concrete. However, I noticed this structures in the south of Köln/Bonn airport (CGN) (&lt;a href=&quot;https://www.google.de/maps/@50.8591262,7.139143,1848m/data=!3m1!1e3?hl=de-DE&quot; rel=&quot;noreferrer&quot;&gt;Google maps link&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wW9eQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wW9eQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know what's the reason behind this unusual shapes?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just found the &lt;a href=&quot;https://www.google.de/maps/place/Br%C3%BCggen/@51.1966762,6.1254354,2350m/data=!3m1!1e3!4m2!3m1!1s0x47c75220581e7b27:0x42760fc4a2a7670!6m1!1e1&quot; rel=&quot;noreferrer&quot;&gt;Royal Airforce Base Brüggen&lt;/a&gt; with lots of dispersal areas. Some with hangars, some with banks of earth like in the black/white picture in aeroalias' answer. It's also a perfect example for the conceptional layout. (And between the areas in the south, there are even typical bunkers for explosives)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/qtjfJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qtjfJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-10-06T07:22:06.520" LastActivityDate="2015-10-06T07:22:06.520" Title="What's the reason for this frog finger shaped parking lots at Köln/Bonn airport (CGN)?" Tags="&lt;airport-design&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21149" PostTypeId="2" ParentId="21145" CreationDate="2015-09-22T19:39:56.183" Score="7" Body="&lt;p&gt;Several things come to mind, but they will all reduce efficiency and/or cost money, so they will not be popular with engine users:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For turbofans: Reduce the &lt;a href=&quot;https://en.wikipedia.org/wiki/Inertia#Rotational_inertia&quot; rel=&quot;nofollow&quot;&gt;rotational inertia&lt;/a&gt; of the spinning parts by reducing the bypass ratio. Inertia is mass times distance, so making the engine diameter smaller should have the biggest effect.&lt;/li&gt;&#xA;&lt;li&gt;Increase temperature margins for the turbine. Today, the electronic control (called &lt;a href=&quot;https://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;FADEC&lt;/a&gt; for Full Authority Digital Engine Control) will limit the amount of fuel that can be injected into the combustion chamber to limit the temperature in the turbine. By running the turbine hotter for a few seconds the turbine torque can be increased, at the cost of a reduction in the lifetime of the turbine.&lt;/li&gt;&#xA;&lt;li&gt;For turboprops: Reduce blade pitch momentarily to unload the propeller, so more torque is available for spooling up the engine core. This, however, reduces thrust when it is needed most.&lt;/li&gt;&#xA;&lt;li&gt;Reduce secondary loads by disconnecting generators and closing bleed valves. This is already done by todays engine control, however.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The best way of dealing with the slow engine response is operational: Avoid situations where the need for a rapid spool-up might arise or enter those situations not with engines set to idle, but to some medium power setting. Carrier pilots do this routinely by spooling up the engine shortly before touchdown, so they will have the required thrust at their disposal if the tail hook fails to catch any of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Arresting_gear&quot; rel=&quot;nofollow&quot;&gt;arrestor cables&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to RalphJ for pointing out that turboprops use the same tactic. Helicopters never let the engine run in idle while in flight. If less thrust (turboprops) rsp. lift (helicopters) is needed, both adjust pitch to set the desired thrust/lift and keep engine RPM up. Now the mass flow through the engine core is the same as at full thrust, only the amount of heating in the combustion chamber is reduced to adjust the power output of the engine. When more thrust/lift is needed, the pilot adjusts pitch and fuel flow to set the desired thrust/lift level. Since the engine is already running at top speed, the change is not delayed by inertial effects.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-23T06:50:05.380" LastActivityDate="2015-09-23T06:50:05.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21151" PostTypeId="2" ParentId="16881" CreationDate="2015-09-22T22:13:53.127" Score="0" Body="&lt;p&gt;In addition to many other things listed in answers, the biggest thing that pilots can't control from cockpit are &quot;tools&quot; like drunk passengers, cell-phone during flight users, loud passenger groups. And excluded from &quot;tools&quot; category, but still uncontrollable are babies. :)&lt;/p&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2015-09-22T22:13:53.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21152" PostTypeId="2" ParentId="21148" CreationDate="2015-09-22T23:46:52.397" Score="35" Body="&lt;p&gt;@Simon is right. The 'parking lots' are actually dispersal areas in the (previous) military airfield at that place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cologne Bonn Airport started out as an airfield for Luftwaffe in 1938 in what was a former artillery shooting range. After war, RAF took over the airfield, with the first civilian flights in September 1950. The airfield was converted for full civilian use only in 1957.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WniJs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WniJs.jpg&quot; alt=&quot;Koln/Bonn airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Koeln-Bonn-Airport14.jpg#/media/File:Koeln-Bonn-Airport14.jpg&quot; rel=&quot;noreferrer&quot;&gt;Koeln-Bonn-Airport14&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Borsi112&quot; rel=&quot;noreferrer&quot; title=&quot;User:Borsi112&quot;&gt;Borsi112&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The original 1886m (32L/14R) runway is near the bottom of the image (near the dispersal area). The top runway, 3800m in length (32R/14L), was opened in 1961.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In military sirfileds, the parked aircrafts are usually dispersed in order to reduce vulnerability in case of an air raid. According to US Army Field Manual 5-430-00-2 (accessed via globalsecurity.org)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If dispersal of aircraft is possible and consistent with active defense measures, varied parking patterns provide fewer lucrative targets for indirect-fire weapons. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also gives some (conceptual) layouts for aircraft dispersal:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/osQHi.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/osQHi.gif&quot; alt=&quot;Dispersal Area&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: globalsecurity.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft are parked in such a way as to reduce the probability that more than one aircraft is hit simultaneously. These dispersal areas have banks of earth or small walls around them to reduce the aircrafts’ susceptibility to the effects of bombs landing nearby and to reduce collateral damage in case one of them blow up. It might've looked like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pBK89.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pBK89.jpg&quot; alt=&quot;Aircraft shelter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: portalnews.gq&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-23T11:33:24.343" LastActivityDate="2015-09-23T11:33:24.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21154" PostTypeId="1" AcceptedAnswerId="21155" CreationDate="2015-09-23T02:05:36.393" Score="-7" ViewCount="1726" Body="&lt;p&gt;I do know that the blades on a propeller generate lift to provide a force pushing back on the air based on newton's law the 2nd. What I am having trouble understanding is how the blades generate thrust by cutting through the air? I know that helicopter hover because they push air downwards, but on a propeller the angle of the blades is much different than of a helicopters blades. Also I don't understand a zero lift configuration. I am having a lot of trouble understanding how helicopters push air downwards, as you can see in this picture&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PlvWp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PlvWp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airfoil doesn't look at all like it can push air downwards. I hope you guys can understand my confusion with this subject. Also I have looked this up on google and was provided answers that were way too confusing for me to understand, so can you give me an answer that is easy to understand. Thanks.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="675" LastEditDate="2015-09-23T02:42:04.620" LastActivityDate="2015-09-23T11:49:00.140" Title="How do the propeller blades accelerate air resulting in thrust to push an aircraft forward?" Tags="&lt;helicopter&gt;&lt;propeller&gt;&lt;lift&gt;&lt;airfoil&gt;&lt;blade&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-09-23T06:17:50.017" ContentLicense="CC BY-SA 3.0" />
  <row Id="21155" PostTypeId="2" ParentId="21154" CreationDate="2015-09-23T04:37:45.380" Score="3" Body="&lt;p&gt;Propeller blades or rotor blades are like wings: They move through the air, and when they have &lt;a href=&quot;https://aviation.stackexchange.com/questions/16193/how-do-wings-generate-lift/16202?s=7%7C0.0395#16202&quot;&gt;the right angle of attack&lt;/a&gt;, they bend the air back- (in case of a propeller) or downwards (in case of the helicopter). On a wing, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=4%7C0.0506#8882&quot;&gt;this causes downwash&lt;/a&gt;, on a propeller this causes prop blast. &lt;strong&gt;Both are really the same&lt;/strong&gt;. Air gets a kick in a direction orthogonal to the movement of the airfoil, be it on a wing, a propeller or a rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make sure the angle of attack is right, a helicopter rotor uses a mechanism called &lt;a href=&quot;https://aviation.stackexchange.com/questions/16060/how-are-helicopter-cyclic-and-collective-jacks-connected/16159?s=1%7C0.4564#16159&quot;&gt;collective pitch control&lt;/a&gt; to vary the angle of attack on all blades simultaneously. In addition, the rotor airfoil is carefully trimmed to have no chordwise shift in the center of pressure over angle of attack. Note that the rotor blade in the picture attached to your question has a small vane at the trailing edge: This is bent slightly upwards to trim the whole rotor such that it will not be twisted by aerodynamic loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please do yourself a favor and follow all the links to other answers here on Aviation SE (it's only three links), and read them carefully. This should help to cure your confusion.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-23T11:49:00.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21156" PostTypeId="2" ParentId="21112" CreationDate="2015-09-23T08:33:31.530" Score="5" Body="&lt;p&gt;Many people mentioned the difference in the shape of the wings and airfoils. But even if you just simply downscale a real glider to a 5 cm wingspan it won't fly as well as the big one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number&lt;/a&gt; for the small scale plane is very small and the viscous drag becomes large. Turbulence will not be strong enough to prevent flow separation at angles of attack which are still OK for the real plane, because the laminar boundary layer is more susceptible to separation. The separation strongly reduces the generated lift and may lead to stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't mean your paper plane will always stall, but you must be careful with the angle of attack and play with the centre of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small models have to use special low &lt;a href=&quot;http://m-selig.ae.illinois.edu/pubs/Selig-2003-VKI-LRN-Airfoil-Design-Lecture-Series.pdf&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number airfoils&lt;/a&gt;, but will never be as efficient as larger gliders, because the skin friction drag is so important. Even typical radio controlled glider models are usually much larger than typical paper planes.&lt;/p&gt;&#xA;" OwnerUserId="3189" LastEditorUserId="3189" LastEditDate="2015-09-23T08:38:38.463" LastActivityDate="2015-09-23T08:38:38.463" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21160" PostTypeId="1" AcceptedAnswerId="21166" CreationDate="2015-09-23T11:13:30.720" Score="26" ViewCount="4181" Body="&lt;p&gt;I've seen the &lt;a href=&quot;http://www.youtube.com/watch?v=_gqWeJGwV_U&quot;&gt;video of the A380 evacuation test&lt;/a&gt; and similar ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the fast evacuation is impressive, a criticism often heard (and read in the comments on YouTube) is that these people were prepared and (roughly) knew what was about to happen. Also, people in the back of the queue were not in fear of their lives, so they just waited on their turn.&lt;br&gt;&#xA;No one tried to go against the stream to look for loved ones seated in different rows, no one tried to get at their personal belongings to try and take those with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What measures are taken to make evacuations tests as realistic as possible?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard that incentives are offered to passengers to get out as fast as possible, for instance $100 for the first &lt;em&gt;X&lt;/em&gt; passengers to get out. Is that true? If not, anything else?&lt;br&gt;&#xA;I of course appreciate the conflicting interests that while ideally the test should be as realistic as possible, the test passengers can't be endangered.&lt;/p&gt;&#xA;" OwnerUserId="2556" LastEditorUserId="2556" LastEditDate="2015-09-23T11:53:55.270" LastActivityDate="2015-09-24T19:30:09.553" Title="How are evacuation tests made as realistic as possible?" Tags="&lt;evacuation&gt;" AnswerCount="5" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21161" PostTypeId="2" ParentId="21160" CreationDate="2015-09-23T11:41:07.140" Score="6" Body="&lt;p&gt;IIRC, the passengers that were interviewed in the video you linked to explicitly said that they did &lt;em&gt;not&lt;/em&gt; know exactly what was about to happen. They only knew they were going to have to evacuate in the dark with debris on the floor with half of the exits inoperable. They did &lt;em&gt;not&lt;/em&gt; know &lt;em&gt;when&lt;/em&gt; the evacuation was going to happen; they sat around in a dark plane for an indeterminate amount of time. If your airplane is crashing, you pretty much also know all of that in advance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likewise, in a real evacuation, there is an even bigger incentive than a stack of dollar bills to get out fast: your life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the A380 evacuation certification test actually &lt;em&gt;did&lt;/em&gt; lead to one injured test passenger. The most unrealistic part is the vast number of people helping with the evacuation on the ground outside of the airplane. However, those do not affect the speed of the evacuation, only prevent serious injuries (e.g. by getting people off the slides more quickly than in a real evacuation, preventing a possible &quot;pile-up&quot; with passengers slamming into one another at high speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of them look pretty well disoriented to me in the IR videos.&lt;/p&gt;&#xA;" OwnerUserId="3721" LastEditorUserId="3721" LastEditDate="2015-09-23T15:59:56.150" LastActivityDate="2015-09-23T15:59:56.150" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21162" PostTypeId="2" ParentId="21160" CreationDate="2015-09-23T11:41:46.357" Score="0" Body="&lt;p&gt;May be paid too, in mock drill aircraft manufacturer/airliner wants to show this as added advantage for how fast evacuation can be done in that particular model of aircraft. If they have not paid for this activity, then passengers might not be as quick as you can observe them in video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in software companies, when they do Fire mock drill, you can see employees coming out of the company slowly and record the time with very slowest evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming to point &quot;test should be as realistic as possible&quot; - you may really need to simulate the evacuation (may be accident/emergency) to continue this evacuation&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;In case if accidents &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For passengers, it might not be easy to cross all the possible hurdles created by accident&lt;/li&gt;&#xA;&lt;li&gt;Passengers near the evacuation doors are not giving up the way&lt;/li&gt;&#xA;&lt;li&gt;Emergency Doors might not be opening as quick as you will able to do it in mock drill&lt;/li&gt;&#xA;&lt;li&gt;Accidents will not cause same damage/scenario each time it occurs&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With all these reasons you will not be able to evacuate passengers as fast as you do it in mock drills.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how (on what basis) this particular equipment is certified.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="9966" LastEditDate="2015-09-23T11:45:41.150" LastActivityDate="2015-09-23T11:45:41.150" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21163" PostTypeId="1" AcceptedAnswerId="21172" CreationDate="2015-09-23T12:33:17.690" Score="3" ViewCount="793" Body="&lt;p&gt;Charles de Gaulle airport (CDG/LFPG) in Paris had great expansion in the new century, including new runways and terminal 2 buildings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What was the airport layout before the great expansion?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="2171" LastEditDate="2015-09-23T14:24:51.060" LastActivityDate="2015-09-24T06:27:15.920" Title="What did Paris' de Gaulle airport look like before the t2 expansion?" Tags="&lt;airport&gt;&lt;aviation-history&gt;&lt;france&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21164" PostTypeId="2" ParentId="21097" CreationDate="2015-09-23T12:58:54.957" Score="2" Body="&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt; : This answer doesn't answer OP's request for the reasons why... However, some people looking for an answer such as the one asked by OP already knows the rules, and agree with it &lt;strong&gt;only&lt;/strong&gt; when there is a &lt;em&gt;critical risk of death&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you see that slide deploying, just assume one simple principle, even if you don't smell any fuel fume nor see any flame or smoke. Slides aren't deployed for fun. They are deployed because the situation is so critical that the evacuation cost is probably less than any other of the remaining outcome (injured people, deaths ?)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Rules are there for a reason !&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's only &lt;strong&gt;one thing&lt;/strong&gt; that can put an end to the internet bashing over people (if that's the problem) who bring their stuff with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because you can't educate 7 trillion different people the same way (&gt;80% doesn't listen carefully to emergency guidelines) and make all of them suddenly understand their 20,000&lt;code&gt;$&lt;/code&gt; camera is not worth risking one single live (prepare to be sued and you'll spend at least 100,000&lt;code&gt;$&lt;/code&gt; if one died - simple math)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cabin luggage :&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;less than 4Kg (8lbs)&lt;/li&gt;&#xA;  &lt;li&gt;under 0.40m x 0.20m x 0.30m (100in x 50in x 76in)&lt;/li&gt;&#xA;  &lt;li&gt;without any sharp component&lt;/li&gt;&#xA;  &lt;li&gt;and with a safe and strong handle.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then, no problem, everyone can bring his stuff with him upon evac. Simple rule, no possible sueing. You have your (critical) medication, your passport, business documents, credit card or cash, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This answer doesn't really addresses the asked question; however, the asked question is an open and endless debate (pros and con) and have precise answer from the airline industry (NO ! There is no possible compromise when it comes to safety concerns), while mitigated answers from passengers point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you're not in the industry, never experienced a fullpanic emergency situation and lucky enough to get out alive or unharmed, you can't measure the importance of safety rules. That happens everyday : you can repeat passing that red stop until the day you have an accident. In similar cases, the only thing that works in a certain extent is strengthening the rules by removing the problem &lt;strong&gt;at the source&lt;/strong&gt;, instead of trying to fix a design flaw at a later stage : disallows those large luggages in cabin ! Not the most seducing solution, but working (if correctly applied)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note : I may blame the crew for their severity, but I won't because I understand. I may blame some passengers with their huge bags (putting those behind at rish because that plane full of fuel CAN explode) but I won't because I understand, they are in panic, or not knowing the rules and aren't aware of anything else than themselves (my point is everyone has his own limit when put in extreme situations - you can't expect from everyone to get 100% prepared for the 987 possible scenarios on each flight while thinking of others)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I'm just both happy noone were injured on this case&lt;/em&gt; - &lt;strong&gt;EDIT: Wrong ! there were injuries&lt;/strong&gt; -, and sad the practice has taken a so wide and careless proportion. If that continues, statistically, one big bad thing will happen sometime in the future, for sure.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="3879" LastEditDate="2015-09-23T17:09:05.427" LastActivityDate="2015-09-23T17:09:05.427" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21165" PostTypeId="2" ParentId="21160" CreationDate="2015-09-23T13:45:57.110" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What measures are taken to make evacuations tests as realistic as possible?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The maximum possible number of &quot;crew&quot; and &quot;passengers&quot; are used.&lt;/li&gt;&#xA;&lt;li&gt;There are rules about the mix of ages and sexes.&lt;/li&gt;&#xA;&lt;li&gt;The &quot;passengers&quot; are not briefed or trained in advance.&#xA;They must not have participated ina similar exercise in the last 6 months&lt;/li&gt;&#xA;&lt;li&gt;The aisles and exit routes are strewn with luggage&#xA;I think it is typical carry-on luggage. About half the&#xA;likely contents of overhead storage in a full plane.&lt;/li&gt;&#xA;&lt;li&gt;Half the exits are declared inoperative&lt;/li&gt;&#xA;&lt;li&gt;There are financial incentives to get out quickly&lt;/li&gt;&#xA;&lt;li&gt;Passengers are prevented from seeing what is happening outside (I think)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-09-23T13:45:57.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21166" PostTypeId="2" ParentId="21160" CreationDate="2015-09-23T14:04:26.183" Score="48" Body="&lt;p&gt;The only ‘realistic’ way of carrying out a full scale evacuation of an aircraft would be to put people in it and set it on fire. That said, FAA takes some efforts to keep the evacuation tests as realistic as possible without seriously endangering the safety of the 'passengers'. The FAA Advisory Circular &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1019850&quot; rel=&quot;noreferrer&quot;&gt;25.803-1A - Emergency Evacuation Demonstrations&lt;/a&gt; lays out some rules regarding this.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Only &lt;em&gt;half&lt;/em&gt; the exits are used for evacuation by a representative mix of passengers, with some debris (luggage, pillows etc) strewn in the path.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft is to have the maximum number of passengers and flight crew, with a representative mix of age and genders with dolls for children.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Not training &lt;em&gt;any&lt;/em&gt; of the participants in the test, i.e. both the flight crew and the participants are not trained to evacuate the (that particular) aircraft. According to the Advisory Circular,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The flight attendants should not be trained for specific demonstration conditions, except that specific training should be given which relates to the safety of the participants prior to and during the demonstration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The participants are clearly told what they are going to do.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The prospective participants should be informed of the purpose of the demonstration and the expected duration of their participation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Though the participants know 'why' they are there, they are not supposed to know 'when' demonstration is going to start.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Neither the crew nor passengers should hear or otherwise receive any indication that the demonstration is about to begin. The first indication to participants should be the extinguishing of the normal cabin lighting.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The participants should not know about the evacuation plan beforehand.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If safety devices or any other equipment external to the airplane could indicate to the test participants which exits are to be used in the demonstration, passengers and crew should enter the airplane through a tunnel or other means that will prevent them from seeing that indication. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The participants are more than likely paid (employees with previous knowledge of the system are not allowed), though there is no mention of any 'prize' for first getting out. The regulations simply state, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Prospective participants should be informed of any direct benefits to them (e.g., pay, meals, etc.) and of benefits to society&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The participants are prevented from interacting with outside and to recieve any information from outside the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...exterior windows should be obscured from the outside to prevent both viewing of the outside conditions and any ground lighting from shining into the airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is intense debate over how 'realistic' the evacuation tests are. For example, the evacuation of &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airtours_Flight_28M&quot; rel=&quot;noreferrer&quot;&gt;British Airtours Flight 28M&lt;/a&gt;, a Boeing 737 took more than 5 minutes (resulting in the deaths of more than 50 people), though the aircraft had passed the test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;em&gt;&lt;a href=&quot;http://ota.fas.org/reports/9306.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Evacuation Testing: Research and Technology Issues&lt;/a&gt;&lt;/em&gt;, there are multiple problems with this type of testing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is only one data point (Full scale evacuation tests are costly; each one costs nearly $1m)&lt;/li&gt;&#xA;&lt;li&gt;The conditions do not reflect the actual ones experienced (for example, fire, smoke etc.)&lt;/li&gt;&#xA;&lt;li&gt;The participants know why they are there (Employees of the manufacturer are not barred, though they may not sit near the exits).&lt;/li&gt;&#xA;&lt;li&gt;The participants do not reflect the actual demographics of the flying public, and if considered, increased the evacuation time significantly (obviously, disabled people and kids are not there in demonstration).&lt;/li&gt;&#xA;&lt;li&gt;The participants do not experience any trauma. Of course adding smoke or fire is not an option as already around 4-5 percent people are getting hurt.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j7hog.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j7hog.png&quot; alt=&quot;Evacuation Graph&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aircraft Evacuation Testing: Research and Technology Issues&lt;/em&gt;&#xA;September 1993 OTA-BP-SET-121 NTIS order #PB94-107620&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result of the aforementioned BA28M accident, UK's, Cranfield Institute of Technology (CIT) carried out a number of tests which included a case where financial incentives were offered to foster competitive behavior among&#xA;test participants. The study determined that, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the presence of a competitive element had a significant impact on egress&#xA;  rates for evacuations through the bulkheads, but did not affect the rate of evacuation through the Type III exit&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note: According to FAA, This type is a rectangular opening of not less than 20 inches wide by 36 inches high, with corner radii not greater than one-third the width of the exit, and with a step-up inside the airplane of not more than 20 inches. If the exit is located over the wing, the step-down outside the airplane may not exceed 27 inches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US Department of Transportation also carried out studies, which resulted in similar conclusions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ij3sC.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ij3sC.png&quot; alt=&quot;Clear Air versus smoke&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aircraft Evacuations Onto Escape Slides and Platforms I: Effects of Passenger Motivation&lt;/em&gt;, DOT/FAAAM-96/18&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The study found that the introduction of smoke did not have much effect, but noted, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although this research design biased against revealing any deleterious effects of smoke on egress, previous studies using smoke had shown robust reductions in egress speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Giving monetary incentives to participants reduced the time required for egress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IKMh8.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IKMh8.png&quot; alt=&quot;Incentive&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aircraft Evacuations Onto Escape Slides and Platforms I: Effects of Passenger Motivation&lt;/em&gt;, DOT/FAAAM-96/18 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this study, the 'competitive' group were offered a financial bonus of $50 to be among the first 25% passengers to evacuate the arcraft. However, the passengers in the competitve trials&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...(became) more aggressive and climbing over seats, outmaneuvering other passengers, etc. to get out quickly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;resulting in broken over seat backs, among others. I suspect participant safety is the main reason FAA doesn't offer any incentives duing demonstration. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of these reasons, simulations are being increasingly used in modelling evacuations which include variables like crowd behavior, state (of the person), mobility, etc.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1372" LastEditDate="2015-09-24T19:30:09.553" LastActivityDate="2015-09-24T19:30:09.553" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21168" PostTypeId="1" AcceptedAnswerId="21175" CreationDate="2015-09-23T16:11:56.053" Score="13" ViewCount="1691" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/a/21126/2556&quot;&gt;the answer to another question&lt;/a&gt; I learned that the call sign &lt;em&gt;Air Force One&lt;/em&gt; (or &lt;em&gt;Marine One&lt;/em&gt;, &lt;em&gt;Navy One&lt;/em&gt; or &lt;em&gt;Executive One&lt;/em&gt;) is transferred &lt;em&gt;immediately&lt;/em&gt; to the aircraft currently carrying the president of the USA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When president Obama visited the Netherlands (and probably on other occasions as well), I remember him arriving in one of two identical helicopters, to not give away his aircraft to would-be attackers. Using the call sign &lt;em&gt;Marine One&lt;/em&gt; for either would defeat that purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So are additional call signs used in such a situation?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2556" LastEditorUserId="15311" LastEditDate="2019-04-06T12:52:58.407" LastActivityDate="2019-04-06T12:52:58.407" Title="Do presidential aircraft use additional call signs?" Tags="&lt;call-sign&gt;&lt;air-force-one&gt;&lt;head-of-state-transport&gt;&lt;marine-one&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21169" PostTypeId="2" ParentId="21168" CreationDate="2015-09-23T17:42:27.623" Score="3" Body="&lt;p&gt;When the president travels, a TFR (VIP Movement) is issued. This ensures that other non-authorized airplanes are not in the vicinity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The president generally does not travel to places where there is a chance of such insecurity. Although sometimes they take precautionary measures like &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Force_One#Other_presidential_aircraft&quot; rel=&quot;nofollow&quot;&gt;as mentioned here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 8 March 2000, President Clinton flew to Pakistan aboard an unmarked&#xA;  Gulfstream III while another aircraft with the call sign &quot;Air Force&#xA;  One&quot; flew on the same route a few minutes later.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Executive_One&quot; rel=&quot;nofollow&quot;&gt;Executive One&lt;/a&gt; is also used as a call sign for the president.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-09-23T17:42:27.623" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21170" PostTypeId="1" AcceptedAnswerId="21179" CreationDate="2015-09-23T17:54:34.263" Score="9" ViewCount="58101" Body="&lt;p&gt;In the operating handbooks for GA aircraft, there are often weight and balance limitations listed for both &lt;strong&gt;Normal&lt;/strong&gt; and &lt;strong&gt;Utiltity&lt;/strong&gt; category operation.  If I restrict the loading to the Utility category envelope, I want to know what regulations and prudence allow me to do over the Normal category envelope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am guessing that there are a set of regulatory certification standards for each category, as well as a list of specific restrictions for each type certificate.  What are these definitions and where are they found?&lt;/p&gt;&#xA;" OwnerUserId="182" LastEditorUserId="1696" LastEditDate="2018-04-23T02:07:32.377" LastActivityDate="2018-04-23T02:07:32.377" Title="What are the differences between Normal and Utiltiy Categories" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;&lt;aircraft-operations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ClosedDate="2015-09-23T23:09:08.457" ContentLicense="CC BY-SA 3.0" />
  <row Id="21171" PostTypeId="1" AcceptedAnswerId="21204" CreationDate="2015-09-23T19:02:01.207" Score="4" ViewCount="406" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/21149/5517&quot;&gt;this answer&lt;/a&gt; to a question about reducing engine spool-up time, &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%c3%a4mpf&quot;&gt;Peter Kämpf&lt;/a&gt; said:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When more thrust/lift is needed, the pilot adjusts pitch and fuel flow to set the desired thrust/lift level. Since the engine is already running at top speed, the change is not delayed by inertial effects.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems to me that &lt;code&gt;landing mode&lt;/code&gt; or &lt;code&gt;critical mode&lt;/code&gt; switch for the engines which would cause the FADEC to spin-up the engine and control power by fuel flow instead would eliminate the lag and increase the likelihood of survival during critical flight regimes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, encountering a micro-burst during landing will leave the plane wanting power as it flys out of the burst and has a tail-wind, often at low power and low altitude. If, in that situation, the pilot applying additional throttle increased the fuel flow and gave immediate power instead of having to wait for the engines to spool, it seems that would be very advantageous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have I understood the concepts correctly, and, if so, what drawbacks to this system might I be missing?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-24T17:25:33.280" Title="Would this work to reduce turbine engine spool times?" Tags="&lt;safety&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21172" PostTypeId="2" ParentId="21163" CreationDate="2015-09-23T19:14:23.810" Score="3" Body="&lt;p&gt;You will hardly find anything complete on the web as :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;at the time of the expansion a bunch of years ago, you didn't have that much computer assisted medias to produce representative documents.&lt;/li&gt;&#xA;&lt;li&gt;most accurate documents are inside old books you can only access at specialized libraries, rare copies owned privately or museums.&lt;/li&gt;&#xA;&lt;li&gt;Because Charles de Gaulle is a french airport, you'll likely to find what you're looking for in french !&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I do have an Air France magazine with Charles de Gaulle history til 2002, and another dedicated to the Terminal 2F extension, but because those are copyrighted materials, I can't post them here. Sorry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though, you can head to the following sites :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.entrevoisins.org/paris-charles-de-gaulle-de-1945-1975.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.entrevoisins.org/paris-charles-de-gaulle-de-1945-1975.aspx&lt;/a&gt;&#xA;(video - if you don't mind quality of the era)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aeroportsdeparis.fr/groupe/presse/40-ans-paris-cdg/photographies&quot; rel=&quot;nofollow&quot;&gt;http://www.aeroportsdeparis.fr/groupe/presse/40-ans-paris-cdg/photographies&lt;/a&gt;&#xA;(a couple pictures)&#xA;&lt;a href=&quot;http://airinfo.org/2014/03/07/paris-charles-de-gaulle-fete-ses-40-ans-video-photos/&quot; rel=&quot;nofollow&quot;&gt;http://airinfo.org/2014/03/07/paris-charles-de-gaulle-fete-ses-40-ans-video-photos/&lt;/a&gt; (dedicated copy of the above)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.goussainlivres.com/librairie/librairie/aeroport-roissy-charles-de-gaulle=198.html&quot; rel=&quot;nofollow&quot;&gt;http://www.goussainlivres.com/librairie/librairie/aeroport-roissy-charles-de-gaulle=198.html&lt;/a&gt;&#xA;(one small cropped overview from a book - bear in mind that most relevant structures of the airport is inside that picture and everything around are empty areas)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, you only had the Terminal 1, and one runway. Airport name was &quot;Paris Nord&quot; before becoming &quot;Roissy-en-France&quot;, then finally called &quot;Charles de Gaulle&quot; just before inauguration (8 of March, 1974). And initial planned extensions were identical copies of the Terminal 1 all other the place including where T2 and T3 are today. Sorry, I can't post a plan from the Air France book, but it's rather similar to the one you can spot in the video above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also rare documents you could retrieve from old magazines issued at the time (Air &amp;amp; Cosmos to name the one I know of) or magazines like EntreVoisins (used to collect them at Maison de l'Environnement, Athis-Mons, near Delta Museum) which sometimes raises issues about noise pollution from Paris Airport platforms (comparative maps of the airport through the years)&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="3879" LastEditDate="2015-09-24T06:27:15.920" LastActivityDate="2015-09-24T06:27:15.920" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21173" PostTypeId="1" AcceptedAnswerId="21176" CreationDate="2015-09-23T19:21:54.810" Score="14" ViewCount="912" Body="&lt;p&gt;Consider Homestead Airport, a fictional paved, non-towered airfield in the exurbs of Bigtown, USA that has become popular as a home field for recreational pilots. The airport's busy enough that addressing &quot;Homestead traffic&quot; on MULTICOM any given daylight hour isn't just talking to yourself; there will be at least one other plane in the pattern and a couple more on the ground, however there isn't enough traffic yet to justify hiring ATCOs to run the field. The sole runway is 13/31.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Saturday in question, there's a southeasterly wind at sunrise and so traffic starts the day using runway 13. However, the wind suddenly changes just after noon as a norther blows through, such that the five or six aircraft currently in the traffic pattern now need to use runway 31.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the standard procedure, if any, to establish the new traffic pattern at the airfield given the wind change? I'm especially curious as to how traffic already in a pattern for the now-downwind runway would be expected to maneuver to establish the new pattern, especially if the segmented circle or AFD indicate traffic should stay to one side of the airport regardless of runway direction (for instance a left-hand pattern on runway 13 but a right-hand on 31, to keep traffic away from a developed neighborhood to the southwest).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus question: At the time a transition to the new runway direction is needed, there is an aircraft holding short for runway 13, with another behind him. These aircraft need to taxi down to the other end of the airfield, and quickly, or they'll be staring at the nosecones of exiting planes. There is a single taxiway, too narrow to 180 on especially with other aircraft using it, and the nearest runway exit is halfway down the field, so aircraft on the ground must taxi down the runway in the opposite direction to get to the correct end. What radio comms are recommended/required to advise traffic in the pattern that the runway has taxiing traffic?&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-23T21:26:32.253" LastActivityDate="2015-09-23T21:26:32.253" Title="How do pilots &quot;turn an airport around&quot; at nontowered fields?" Tags="&lt;radio-communications&gt;&lt;non-towered-airport&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21174" PostTypeId="2" ParentId="21173" CreationDate="2015-09-23T20:36:09.337" Score="4" Body="&lt;p&gt;This is complex and unfortunately can create a dangerous situation. I fly out of KDYL and have seen a similar situation occur. Generally what I see is not that the wind changes but that there is no wind so both directions are used. The fact of the matter is, at an untowered airport the runway choice is up to you unless specific conditions are specified in the AF/D. The problem is that many people forget that or simply do whats easiest. At DYL the calm wind runway 05 which is great if you are departing to the east or north but I have seen plenty of people use 23 on calm days to depart to the south and west. Landings are generally justified similarly and people will enter the patter that best fits the flight path they are on. That being said when I fly in and I hear people calling legs of a particular pattern I will go for that as its the assumed pattern at the field. Remember it is your job to observe the flow of traffic as you would if you lost radio communications. If you feel the wind favors the pattern that is not being used you can wait until everyone is on the ground and announce your intentions for the other pattern. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In regards to your bonus question if you decide to taxi back (go down the runway to the other end) on the active you should not do so unless there are no approaching planes. Likewise once you have stated you have entered the active for a taxi back (and announced as such) no one else should be taking the active from the other end to take off. You should not be entering the active for taxi back if anyone is on approach unless the taxiway at the other end is free to leave the active in time. Thus you &lt;strong&gt;SHOULD NOT&lt;/strong&gt; encounter other aircraft but people are people so that does not mean you &lt;strong&gt;WILL NOT&lt;/strong&gt; encounter them. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-23T20:36:09.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21175" PostTypeId="2" ParentId="21168" CreationDate="2015-09-23T20:44:49.433" Score="20" Body="&lt;p&gt;When multiple U.S. military aircraft are operating in formation, they do so as a &quot;flight&quot;. This flight has a callsign, and in the case of Presidential transport flights, this callsign is the Presidential one, such as Air Force One or Marine One.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For POTUS transport using a fixed-wing aircraft, the flight typically consists of a single aircraft, usually one of the VC-25s specifically built for the purpose. Its fighter escort, if any (typically there is one), is a different &quot;flight&quot; that operates in tandem with Air Force One as the escort &quot;element&quot; of the complete transportation &quot;package&quot;. Therefore, for Air Force One and for Navy or Executive fixed wing equivalents, the aircraft is the flight and has the callsign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the &quot;Marine One&quot; helicopters must be used, however, a very sophisticated &quot;shell game&quot; is played, as you already know. Not only are multiple helicopters used (I've seen up to 6 in use at the same time), they are externally identical in appearance, and they change position in the flight formation constantly. The Secret Service has even gone so far as to use body doubles that would make positive ID of the helicopter the actual President has entered difficult, even if an enemy faction had spotters in place to track each individual helicopter's position in the flight the whole time it's in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This entire flight of multiple helicopters is what carries the &quot;Marine One&quot; callsign. Individual aircraft within the flight, if typical military radio procedures are followed, would be identified by adding a craft number suffix: &quot;Marine One-One&quot;, &quot;Marine One-Two&quot;, etc. I don't know whether the aircraft change craft numbers during flight to match formation position, or if the pilots just keep track of which chopper's where as they juggle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, a potential assassin would either have to take a 50-50 shot (or worse) at one of the choppers in the flight, or he'd have to coordinate with multiple launchers to attack all the choppers simultaneously (and the larger the effort, the more communication is required to plan and execute it, which increases the group's exposure and the potential for detection). If there is any reliable intel that the President would be targeted with this level of sophistication during a visit, he usually doesn't go; he has a VP, a Secretary of State and a cadre of ambassadorial representatives whose job it is to personally represent the President anywhere in the world the President himself cannot be, for any reason.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-23T21:06:57.777" LastActivityDate="2015-09-23T21:06:57.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21176" PostTypeId="2" ParentId="21173" CreationDate="2015-09-23T21:02:53.320" Score="10" Body="&lt;p&gt;Your example is too specific to be useful to others, so let's consider the general case instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At an untowered field there is no &quot;active&quot; runway - they're &lt;em&gt;all&lt;/em&gt; active.&lt;br&gt;&#xA;There is usually a &quot;preferred&quot; runway - the one best aligned into the wind - but any runway can be used by any aircraft at any time, subject to whatever safety considerations the pilots mutually agree on. (At untowered fields with intersecting runways that have a lot of training on the field it's not uncommon to have traffic on the crosswind runway intersecting the preferred runway when students need to practice crosswind landings. It can be coordinated safely with a little cooperation between the pilots involved.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway is &quot;changed&quot; by pilots announcing they're using a different runway.  There may also be a unicom operator at the field who announces a change in the preferred runway and lets incoming aircraft know about it.&lt;br&gt;&#xA;Usually pilots who are already in the pattern for the &quot;old&quot; runway will complete their circuit and land, clearing the runway as expeditiously as possible.&lt;br&gt;&#xA;Similarly pilots waiting at the threshold when the wind shifts may elect to either make their takeoff from where they are, or taxi around to the new preferred runway.  (In a case where the aircraft must enter the runway to turn around, or where they must back-taxi on the runway this obviously needs to be coordinated with the other pilots. The standard phraseology to use for this is &quot;&lt;em&gt;N12345 back-taxiing on runway XX&lt;/em&gt;&quot; )&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To your specific example, the directions of traffic patterns don't really matter much: As I mentioned aircraft already in the pattern will probably complete their circuit and land on the runway they were lined up for. Even in the case of Left Traffic for 13 and Right Traffic for 31 and two aircraft maneuvering to enter the pattern for opposite runways the &lt;em&gt;standard pattern entry&lt;/em&gt; (45-to-downwind) will tend to keep airplanes apart (they won't ever be heading &lt;em&gt;at&lt;/em&gt; each other in the downwind leg if they enter it on the 45, and it should at least ensure they see each other in the opposite-direction 45 and can coordinate to ensure they're never flying &lt;em&gt;at&lt;/em&gt; each other). One airplane will probably have to extend their pattern to allow the other to clear the runway safely before they can land, however.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Traffic really should not really be arriving to both downwinds simultaneously anyway, particularly in your example with a single runway: Inbound aircraft should coordinate to arrive in the pattern for the &lt;em&gt;preferred runway&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft already in the pattern have two choices: Land downwind if safe, or depart the pattern and re-enter it to land on the new preferred runway.  A downwind landing must obviously be coordinated with aircraft which may be preparing to depart in the opposite direction.&lt;br&gt;&#xA;If landing downwind is unsafe (due to wind speed) or otherwise undesirable (e.g. due to other traffic) climbing above pattern altitude, leaving the area, and returning via a standard pattern entry for the opposite runway is usually the safest course of action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft waiting to depart also have two choices: Depart downwind (which must be coordinated with aircraft arriving to the preferred runway), or taxi to the preferred runway end for takeoff. In cases such as you've described where back-taxiing is necessary this must be coordinated with pilots landing (in either direction) as the back-taxiing aircraft will be occupying the runway they need for landing.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The major complicating factor you didn't specifically mention, but which is implied by multiple aircraft &quot;in the pattern&quot; is closed traffic (aircraft making touch-and-go or full-stop/taxi-back landings and immediately taking off again).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Full-Stop/Taxi-Back landings are not a problem: Much like &quot;regular&quot; landing traffic they can land downwind, and upon exiting the runway taxi back to the preferred runway end for their next takeoff.&lt;br&gt;&#xA;Touch-and-Go aircraft have two main choices: Land downwind as a full-stop and taxi around to the preferred runway end (which is probably the safest and most considerate thing to do), or complete a touch-and-go with the intention of departing the pattern and returning to set up for circuits to the new preferred runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another important consideration are &lt;em&gt;aircraft without radios&lt;/em&gt; (NORDO)- yes, these do exist). A visual scan of the traffic pattern is required at any uncontrolled field at any time to ensure you are not conflicting with NORDO aircraft.&lt;br&gt;&#xA;These are often slower planes, so having one in the pattern landing &quot;the wrong way&quot; may require you to wait a while for them to complete their circuit before you can begin operations on the new preferred runway.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-23T21:02:53.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21178" PostTypeId="1" AcceptedAnswerId="21180" CreationDate="2015-09-23T21:21:12.600" Score="3" ViewCount="7476" Body="&lt;p&gt;I know that winglets and swept wings are ways to reduce the vortex that are currently in use on many aircraft. Are there any aircraft design concepts out there that completely eliminate the vortex effect? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XeDWl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XeDWl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="6886" LastEditDate="2015-09-23T22:56:51.640" LastActivityDate="2015-09-23T23:20:56.810" Title="How could it be possible to fully prevent wing tip vortex formation?" Tags="&lt;wing-tip-vortex&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-09-24T11:40:06.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="21179" PostTypeId="2" ParentId="21170" CreationDate="2015-09-23T21:36:15.810" Score="11" Body="&lt;p&gt;From a regulatory standpoint the governing regulation is FAR 23 (airworthiness standards for what we'd generally call &quot;small&quot; airplanes - Normal, Utility, Acrobatic, and Commuter category). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.3.10.1.59.3&quot; rel=&quot;noreferrer&quot;&gt;FAR 23.3&lt;/a&gt; is probably what you're interested in, and tells us:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Normal Category&lt;/strong&gt; is limited to airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for nonacrobatic operation.&lt;br&gt;&#xA;They go on to specify that nonacrobatic operation includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any maneuver incident to normal flying&lt;br&gt;&#xA;(for very vanilla definitions of &quot;normal&quot; - they expect you to use some common sense here!)&lt;/li&gt;&#xA;&lt;li&gt;Stalls (except &lt;a href=&quot;https://aviation.stackexchange.com/questions/18859/what-is-a-whip-stall&quot;&gt;&quot;whip stalls&quot;&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;What most pilots recognize as the &quot;commercial flight test maneuvers&quot;: Lazy eights, chandelles, and steep turns, but with an angle of bank not greater than 60 degrees in any of these maneuvers.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Utility Category&lt;/strong&gt; is the same type and size of airplane, but approved for &quot;limited acrobatic operations&quot; - this &lt;em&gt;may&lt;/em&gt; include intentional spins, as well as the &quot;commercial maneuvers&quot; with higher bank angles (greater than 60 degrees, up to 90 degrees).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Acrobatic Category&lt;/strong&gt; is the same type and size of airplane, but approved for acrobatics  without any restrictions &quot;other than those shown to be necessary as a result of required flight tests&quot; -- basically &quot;airplanes that can go upside-down&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The commuter category is boring: It's basically the normal category, but with more engines (at least 2) and more seats (up to a maximum of 19). Commuter category aircraft can also have a higher maximum takeoff weight (up to 19,000 pounds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft can be certificated in any combination of the Normal, Utility, and Acrobatic categories if the aircraft meets the requirements of the appropriate category (as specified later in FAR 23).  An aircraft certificated in the Commuter category may not be certificated in any of the other categories however.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Generally the restrictions you find on aircraft are not regulatory ones (from the FARs) but Operating Limitations (in the POH or placarded on the aircraft) which you must comply with (per Part 91 of the FARs).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the Cessna 172 and the Piper Warrior are both dual-category aircraft (Normal and Utility), and specify a &quot;Utility Category CG Envelope&quot; in their weight and balance charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Piper Warrior is &lt;em&gt;not&lt;/em&gt; approved for spins in the utility category (they are placarded with &lt;code&gt;SPINS PROHIBITED&lt;/code&gt;). they also have other restrictions for utility category operations which are found in the POH and on aircraft placards (e.g. &lt;code&gt;UTILITY CATEGORY - NO BAGGAGE OR AFT PASSENGERS&lt;/code&gt;, and maximum entry speeds for other acrobatic maneuvers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most Cessna 172s &lt;em&gt;are&lt;/em&gt; approved for spins in the utility category and are not placarded against them. (Certain aircraft with specific STOL kits installed are &lt;em&gt;disapproved&lt;/em&gt; as a result of the kit, and have placards prohibiting them).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-23T21:36:15.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21180" PostTypeId="2" ParentId="21178" CreationDate="2015-09-23T22:18:23.523" Score="3" Body="&lt;p&gt;Wingtip vortices are an unavoidable side effect of producing lift with an airfoil of finite length (thus having &quot;wingtips&quot;). The wing is designed first to have relatively high pressure underneath the wing and lower pressure above it. Second, air passing over the top of the airfoil is directed downwards as it leaves the wing (thus &quot;pulling&quot; the wing upwards by Newton's Third Law). These two characteristics of an airfoil combine to make air around the wingtip want to &quot;spin&quot;; high-pressure air below the wing will &quot;leak&quot; upwards over the wingtip, then be directed back downwards along with the rest of the air, creating the wingtip vortex:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ykpUN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ykpUN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing the pressure differential between air above and below the wing will by definition reduce lift, because it is this pressure differential producing lift. By the same token, reducing the &quot;downwash&quot; off the back of the wing will reduce lift because the force creating the downwash is also lifting the wing. Therefore, conventional wings will produce wingtip vortices by definition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretical ways to reduce this vortex include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Make it harder for air to &quot;leak&quot; upward over the wingtip.&lt;/strong&gt; This is the principle behind the &quot;winglets&quot; you see on many airliners; they prevent air iunderneath the wing being able to move over the top of it, thus reducing the severity of the rotation of the vortex (which reduces drag, which saves the airlines fuel):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Pum5E.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Pum5E.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even small aircraft, like this PiperSport light sport, often have little blended winglets to reduce vortex drag, saving as much available power as possible from the limited-horsepower engines of this class:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WAoLU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WAoLU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A-10's wingtip has a similar idea implemented the opposite way; a slight downward curve to the wingtip holds the &quot;cushion&quot; of higher-pressure air under the wing, reducing the amount of leakage around the wingtip, which lowers the wing's stall speed and also reduces tip vortices:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SIn9Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SIn9Z.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Don't have a wingtip.&lt;/strong&gt; &quot;Nonplanar&quot; wing designs, including ring wings, reduce (but do not eliminate) vortex drag compared to conventional wing planforms simply by not providing a single border between lifting and nonlifting surfaces:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZiaVE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZiaVE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a concept drawing, but the idea of a tipless closed-loop wing has been incorporated into production small planes, like this Belarussian small single:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/orPsV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/orPsV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortex drag is not totally eliminated because there is still a downwash behind the wings relative to the undisturbed air to either side of the plane, but the intensity of the vortex (and thus the energy lost producing it which counts as drag) is reduced considerably. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Reduce the pressure differential at the wingtip.&lt;/strong&gt; This is a major way that swept, delta and double-delta wing planforms reduce tip vortices. Very simply, most modern wings on high-speed or high-performance jets have a smaller chord length and a thinner cross-section at the wingtip than the wing root. This provides less lift at the wingtip (and the wingtip stalls more easily and thus tends to stall first) than a straight wing with a relatively constant cross-section, but the reduction in pressure differential and downwash right at the wingtip reduces the two primary contributors to wingtip vortices:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0cJuX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0cJuX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-09-23T22:18:23.523" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="21181" PostTypeId="1" AcceptedAnswerId="21185" CreationDate="2015-09-23T22:30:01.303" Score="-1" ViewCount="1502" Body="&lt;p&gt;This is a subject I have been very confused with lately about thrust coming from downwash on a propeller and helicopter, but to understand how the downwash increases thrust is to know how it forms and works on a regular aircraft wing. A picture of downwash on a wing would be helpful. And also how does downwash make thrust on a propeller and helicopter wing?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-23T23:14:26.297" Title="What is downwash on a wing and how does it form?" Tags="&lt;wing&gt;&lt;propeller&gt;&lt;lift&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-09-24T01:32:06.923" ContentLicense="CC BY-SA 3.0" />
  <row Id="21182" PostTypeId="1" CreationDate="2015-09-23T22:36:58.853" Score="5" ViewCount="776" Body="&lt;p&gt;The definition of the acrobatic category in FAR 23.3 reads as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) The acrobatic category is limited to airplanes that have a seating configuration, excluding pilot seats, of nine or less, a maximum certificated takeoff weight of 12,500 pounds or less, and intended for use without restrictions, other than those shown to be necessary as a result of required flight tests.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Considering that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop T-38&lt;/a&gt; is a two-seat, twin-engined supersonic jet trainer aircraft with a USAF service maximum takeoff weight of 12,093 lbs (from their factsheet), what traits of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_T-38_Talon&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-38&lt;/a&gt; would have &lt;em&gt;prohibited&lt;/em&gt; Northrop from applying for a civil Type Certificate for the T-38 in the &lt;em&gt;acrobatic&lt;/em&gt; category?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="15311" LastEditDate="2017-12-11T08:58:44.647" LastActivityDate="2019-02-27T17:08:03.787" Title="What would prohibit a T-38 Talon from being certified in the Acrobatic category?" Tags="&lt;faa-regulations&gt;&lt;aerobatics&gt;&lt;aircraft-certification&gt;&lt;t-38&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21184" PostTypeId="2" ParentId="21178" CreationDate="2015-09-23T23:03:01.237" Score="3" Body="&lt;p&gt;Wingtip vortices are unavoidable in a three dimensional lift producing wing. The vortices are a result of the pressure difference that causes the lift. The only ways to eliminate the vortices are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Make the wing two dimensional- i.e. make its span infinite, like an airfoil.&lt;/li&gt;&#xA;&lt;li&gt;Don't produce lift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, neither of these help us much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some points to note are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Winglets and other wingtip devices &lt;em&gt;reduce&lt;/em&gt; the intensity of the vortices, not eliminate them.&lt;/li&gt;&#xA;&lt;li&gt;'Closing' the wing or wing tip &lt;em&gt;does not&lt;/em&gt; eliminate the trailing vortex wake or induced drag. From aero.stanford.edu:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wings that form closed loops ... do not eliminate the &quot;tip vortices&quot; or trailing vortex wakes even though the wing has no tips.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The figure below shows the CFD simulation of wings with different wingtip devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zUtK0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zUtK0.png&quot; alt=&quot;Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aerodynamic Efficiency Study of Modern Spiroid Winglets&lt;/em&gt;, by Tung Wan Hung-Chu Chou Kuei-Wen Lien, Figure numbers removed for proper fit.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-23T23:20:56.810" LastActivityDate="2015-09-23T23:20:56.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21185" PostTypeId="2" ParentId="21181" CreationDate="2015-09-23T23:03:57.547" Score="0" Body="&lt;p&gt;Having in mind a typical flow around an airfoil, the flow over the wing flows much faster than the one under the wing. This faster particles arrive first to the trailing edge and are &quot;projected&quot; against the rest of the flow, creating that additional thrust.&#xA;Moreover, the difference between the free stream and the flow after the trailing edge is the downwash angle. I hope it helped.&lt;/p&gt;&#xA;" OwnerUserId="11121" LastActivityDate="2015-09-23T23:03:57.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21186" PostTypeId="2" ParentId="21160" CreationDate="2015-09-24T00:09:09.610" Score="1" Body="&lt;p&gt;In addition to the other excellent answers, the simulator is equipped with speakers, extra lights, and a fog machine - or at least one airline has such a simulator and I expect others do also. I have done one simply for fun, we were not being timed, and the sound effects, including screaming and weird roaring whooshing noises, plus the orange fire-like light from an unexpected direction and the presence of &quot;smoke&quot; that luckily doesn't smell of smoke all got the adrenaline going and made things more challenging (and therefore realistic) than they otherwise would have been. And we knew exactly what we were doing, we had been offered the treat of experiencing a simulated evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the thing about going backwards - an airline could always instruct someone to misbehave like that, but one of the reasons the target time is set to 90 seconds with only half the exits in use is so that even if such misbehaviours double the exit time, you still get everyone out in 3 minutes. And in real life you have staff who could tell people not to do that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Or other passengers: 30 years ago news reports about &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Canada_Flight_797&quot; rel=&quot;nofollow&quot;&gt;an evacuation from a soon-to-be-burning plane&lt;/a&gt; included tales of the man with the big deep voice who called people over to the exits and urged them to leave during the 90 seconds they got before the smoke turned to flames and those still on board all died, including the folksinger famous for his big deep voice. Two bodies were found far from the exits even though all passengers had moved close to the exits during the descent; it was concluded they had gone past the exits in panic. This is why some airlines instruct you to count rows to the exit from your seat. This flight is also why there are smoke detectors in the lavs.)&lt;/p&gt;&#xA;" OwnerUserId="3827" LastEditorUserId="3827" LastEditDate="2015-09-24T14:25:55.247" LastActivityDate="2015-09-24T14:25:55.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21187" PostTypeId="2" ParentId="21182" CreationDate="2015-09-24T00:15:56.763" Score="9" Body="&lt;p&gt;That an aircraft is &lt;em&gt;eligible&lt;/em&gt; for a category is not a basis to say that the aircraft &lt;em&gt;should&lt;/em&gt; be certified in that category. In other words, though there is nothing prohibiting T-38 being certified in acrobatics category, FAA will not certify it unless someone approaches it for that reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The T-38 would come under military surplus aircraft, which is covered by &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/391918&quot; rel=&quot;noreferrer&quot;&gt;FAA Advisory Circular 20-169&lt;/a&gt; for Military and Special Mission Modifications and Equipment for Commercial Derivative Aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are some &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/AcftRef_Results.aspx?Mfrtxt=&amp;amp;Modeltxt=T-38&amp;amp;PageNo=1&quot; rel=&quot;noreferrer&quot;&gt;T-38s being operated by civilians&lt;/a&gt; in US, which are type certified under FAA Experimental Category (most are used by NASA, Boeing etc for research). &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=938TC&quot; rel=&quot;noreferrer&quot;&gt;One of the aircraft&lt;/a&gt; owned by Thornton Corp. is certified under the 'Exhibition' category, which permits the user,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;to exhibit an aircraft’s flight capabilities, performance, or unusual characteristics for air shows, motion pictures, television, and similar productions, and for the maintenance of exhibition flight proficiency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if this aircraft has been used in that manner though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-24T00:46:07.070" LastActivityDate="2015-09-24T00:46:07.070" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21188" PostTypeId="1" AcceptedAnswerId="21191" CreationDate="2015-09-24T03:05:55.093" Score="28" ViewCount="9919" Body="&lt;p&gt;Without a tail rotor, how does a &lt;a href=&quot;https://en.wikipedia.org/wiki/Coaxial_rotors&quot; rel=&quot;noreferrer&quot;&gt;coaxial rotor helicopter&lt;/a&gt; achieve yaw control? Does a coax have to bank in order to turn?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The link goes to wikipedia's article, and down a ways it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rotational maneuvering, yaw control, is accomplished by increasing the collective pitch of one rotor and decreasing the collective pitch on the other. This causes a controlled dissymmetry of torque.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, I cannot understand what it's saying. AFAIK both rotors always spin at the same RPM because the mechanical engine links are built that way and it's set in stone (correct me if I'm wrong). So I can't see how one rotor makes more torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: related, is this kind of yaw, however it's achieved, slower or faster than yawing in a conventional tail helicopter?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2015-09-24T23:13:55.573" LastActivityDate="2021-03-26T19:06:21.770" Title="How does a coaxial rotor helicopter achieve yaw?" Tags="&lt;helicopter&gt;&lt;engine&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21189" PostTypeId="1" CreationDate="2015-09-24T03:36:30.020" Score="1" ViewCount="442" Body="&lt;p&gt;As the picture below, what are these triangle components for? I find these normally installed under the Flaps. Thanks!!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M9YEU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M9YEU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11354" LastActivityDate="2015-09-24T03:36:30.020" Title="What are these things under Airliners wing?" Tags="&lt;wing&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-09-24T04:13:24.453" ContentLicense="CC BY-SA 3.0" />
  <row Id="21190" PostTypeId="1" AcceptedAnswerId="21192" CreationDate="2015-09-24T04:23:24.220" Score="13" ViewCount="2551" Body="&lt;p&gt;I'm an airplane guy, but I've got a quick helicopter question. I've seen a few helicopters with what seems to be a fin shaped antenna on the middle of the fuselage just above the windshield. I've also seen them just below the cockpit. And sometimes there's two antennas, one above, and one below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PCQLb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PCQLb.jpg&quot; alt=&quot;Items pointed out on a Bell 412 above and below cockpit&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.rth.info/news/news.php?id=450&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just curious what its purpose is?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;antenne balise de detresse&lt;/em&gt; is the one I'm curious about:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rNfBg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rNfBg.jpg&quot; alt=&quot;Antennes de l&amp;#39; EC 145&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11356" LastEditorDisplayName="user33537" LastEditDate="2018-09-04T12:49:32.157" LastActivityDate="2018-09-05T08:17:48.937" Title="What is the purpose of this helicopter fin antenna?" Tags="&lt;helicopter&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21191" PostTypeId="2" ParentId="21188" CreationDate="2015-09-24T04:42:56.233" Score="46" Body="&lt;p&gt;In a conventional helicopter the lift generated by the rotor is controlled by the collective pitch. Raising the collective pitch increases the Angle of Attack of the the rotor blades and consequently the lift, and inevitably increases drag. The drag is overcome by increasing the &lt;em&gt;torque&lt;/em&gt; from the engine. Vertical movement is achieved by balancing the collective pitch against the torque while &lt;em&gt;maintaining a relatively constant rotor speed&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The torque from the engine pushing the rotor one way results in a tendency of the fuselage to rotate in the opposite direction. This is conventionally countered by a tail rotor or other similar device, and varying the force generated by this rotor controls the yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far, so good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a helicopter with coaxial rotors there is no tail rotor, but the torque issue remains. Here, it's resolved by applying equal but opposite torque to each rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift overall is controlled by changing the Angle of Attack of both rotors. If the same inputs are applied to both rotors then the torque remains balanced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the Angle of Attack of one rotor can be increased while that Angle of Attack of the second is decreased, leaving lift overall unchanged. This will increase the drag on the first rotor, and hence the torque required to maintain rotor speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simultaneously, the lift, drag and torque on the second rotor has been reduced, producing an imbalance in the direction of torque between the two rotors, and a consequent yaw moment around the axis of rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this can be achieved without a significant change in rotor speed. In fact, the exact rotor speed doesn't play a part in yaw control.&lt;/p&gt;&#xA;" OwnerDisplayName="user11357" LastActivityDate="2015-09-24T04:42:56.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21192" PostTypeId="2" ParentId="21190" CreationDate="2015-09-24T05:43:52.027" Score="12" Body="&lt;p&gt;It can be quite difficult to see as the big fin in the first photo is a wire cutter and it seems that the arrow points to that.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second photo shows it a little more clearly.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Wire_strike_protection_system&quot; rel=&quot;noreferrer&quot;&gt;It is a wire cutter.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1467" LastEditDate="2018-09-05T08:17:48.937" LastActivityDate="2018-09-05T08:17:48.937" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21193" PostTypeId="2" ParentId="14495" CreationDate="2015-09-24T06:10:16.773" Score="0" Body="&lt;p&gt;Based on the country you are looking for the certification, rules may be slightly changed. For India following syllabus is applicable (Source: atcguild.com)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At present it is a year-long ab-initio training (Under revision to make it in two sections of six months each)&#xA;Modules:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Air Traffic Services&lt;/li&gt;&#xA;&lt;li&gt;Aerodromes and Ground Aids&lt;/li&gt;&#xA;&lt;li&gt;Air Legislation&lt;/li&gt;&#xA;&lt;li&gt;Meteorology&lt;/li&gt;&#xA;&lt;li&gt;Communication Procedures&lt;/li&gt;&#xA;&lt;li&gt;Technical&lt;/li&gt;&#xA;&lt;li&gt;Search and Rescue&lt;/li&gt;&#xA;&lt;li&gt;Air Navigation&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The selection shall be made on the basis of a&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Written test&lt;/li&gt;&#xA;&lt;li&gt;50% questions on subjects relating to educational qualifications&#xA;prescribed&lt;/li&gt;&#xA;&lt;li&gt;50% on General Knowledge, General Intelligence, General Aptitude,&#xA;English etc. Voice test&lt;/li&gt;&#xA;&lt;li&gt;Personal Interview&lt;/li&gt;&#xA;&lt;li&gt;Medical fitness as per ICAO Annex-1&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I Googled for the subject, but didn't find much information on the paper patterns or example papers.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-09-24T06:10:16.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21194" PostTypeId="1" AcceptedAnswerId="21195" CreationDate="2015-09-24T10:58:27.107" Score="16" ViewCount="5079" Body="&lt;p&gt;The following table shows the operating temperature of Jet fuels (Source &lt;a href=&quot;http://www.skybrary.aero/&quot; rel=&quot;noreferrer&quot;&gt;http://www.skybrary.aero/&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know a lot of flights will be cancelled during bad weather conditions including the cold. How is the Engine fuel kept from freezing when the flight is operated at the mentioned fuel freezing temperature?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nz3Br.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nz3Br.png&quot; alt=&quot;Fuel Operational Temperature&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="100" LastEditDate="2015-09-24T11:01:42.170" LastActivityDate="2015-09-27T18:09:19.423" Title="How is engine fuel kept from freezing?" Tags="&lt;jet-engine&gt;&lt;general-aviation&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2015-09-27T07:58:07.190" ContentLicense="CC BY-SA 3.0" />
  <row Id="21195" PostTypeId="2" ParentId="21194" CreationDate="2015-09-24T11:12:29.260" Score="24" Body="&lt;p&gt;There are multiple ways for preventing fuel freezing in aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In large aircraft, the fuel tanks have heating systems.&lt;/li&gt;&#xA;&lt;li&gt;Fuels with low freezing point, like Jet A-1 can be used. In really cold conditions (like Canada, Alska, Russia etc) Jet B (with freezing point -60$^{\circ}$) can be used, though this has higher flammability. The military equivalent of Jet B is the JP-4.&lt;/li&gt;&#xA;&lt;li&gt;An anti-freezing compound, called the the Fuel System Icing Inhibitor (FSII) is added to the fuel to prevent icing. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The problem in aircraft is not the fuel itself freezing, but the free water in aviation fuels freezing. All aviation fuels contain some (small) amount of water, which cannot be extracted. At (high) flight altitudes, the fuel cools and its capacity to retain dissolved water is reduced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the dissolved water separates out as discrete water that can form into ice crystals, blocking filters or form supercooled liquid which can crystallize and form ice crystals when it comes into contact with fuel lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FSII dissolves sparingly in fuel, but more easily in water. Any water present will extract FSII from the fuel; the additive then acts to reduce the freezing point of the free water, preventing the formation of solid ice crystals which could block the fuel supply system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FSII is usually ethylene glycol  monomethyl ether (EGME) or diethylene glycol monomethyl ether (DiEGME). These fuel icing inhibitor additives are mandatory in all military aircraft fuels (like JP8) and are optional in world-wide  commercial aviation fuels depending on route, flight length, and season.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3386" LastEditDate="2015-09-24T12:44:57.397" LastActivityDate="2015-09-24T12:44:57.397" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21196" PostTypeId="2" ParentId="21194" CreationDate="2015-09-24T11:36:41.727" Score="28" Body="&lt;p&gt;In regions and weather conditions where this is likely to be a problem, other fuels are used instead of Jet-A.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Jet-B has a freezing point of -60C and is used during the winter in some parts of Russia and other very cold places.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For information about fuel freezing in flight, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/2185/how-do-aircraft-keep-the-temperature-of-the-fuel-tanks-above-freezing-point&quot;&gt;this previous question/answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-27T18:09:19.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21197" PostTypeId="1" AcceptedAnswerId="21199" CreationDate="2015-09-24T11:48:19.883" Score="11" ViewCount="7007" Body="&lt;p&gt;Related to this question&#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9525/why-did-the-ju-87-stuka-have-a-siren&quot;&gt;Why did the Ju-87 Stuka have a siren?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to know the reasons why they have not changed the engine of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_87&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stuka&lt;/a&gt; when they realised it was easy prey for Hurricanes and Spitfires in 1942/43.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Couldn't they have replaced the engine with a bigger one? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a heavy aircraft, but certainly could have gone through some improvements in order to increase its speed and manoeuvrability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok it is a bomber, not a fighter, but still... &lt;/p&gt;&#xA;" OwnerUserId="11358" LastEditorUserId="22726" LastEditDate="2020-02-22T22:52:56.753" LastActivityDate="2020-02-22T22:52:56.753" Title="Why was the engine of the Ju-87 Stuka not replaced with a more powerful one?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;engine&gt;&lt;wwii&gt;&lt;ju-87&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21198" PostTypeId="1" AcceptedAnswerId="21201" CreationDate="2015-09-24T12:17:42.963" Score="2" ViewCount="1214" Body="&lt;p&gt;I heard that a friend of mine experienced an engine failure in a Jabiru 2200. Does this happen very often and are there other common failures in the Jabiru family of aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2015-09-24T13:49:41.817" LastActivityDate="2015-09-24T15:12:50.263" Title="Do Jabiru aircraft have a long history of engine failures or other technical issues?" Tags="&lt;safety&gt;&lt;engine-failure&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21199" PostTypeId="2" ParentId="21197" CreationDate="2015-09-24T12:30:36.197" Score="19" Body="&lt;p&gt;The Ju-87 Stuka &lt;em&gt;did&lt;/em&gt; undergo engine change during its life. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial Ju-87A version used the &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Jumo_210&quot; rel=&quot;noreferrer&quot;&gt;Junkers Jumo 210&lt;/a&gt; A engine, which produced 602 hp. This was almost immediately replaced with Jumo 210D, which produced around 661 hp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first production version, the Junkers Ju-87 B-1 used a &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Jumo_211&quot; rel=&quot;noreferrer&quot;&gt;Junkers Jumo 211&lt;/a&gt;D generating 1,184 hp. Note this version had the fuselage and landing gear redesigned from 87A.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next major version, the Ju-87D, used a Jumo 211J delivering 1,401 hp, after briefly dabbling with Daimler-Benz DB 603 engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final operational version of Stuka, the Ju-87G, used the Jumo 211J engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is more or less the same path followed by other combat aircraft of the era. For example the Hawker Hurricane MkI used a Merlin III engine producing 1,310 hp, while the last major version, the MkIV used the Merlin 24 (or 27) engines, producing 1,620 hp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the main thrust in engine change in Ju-87 was increasing the payload, rather than increased speed or maneuverability like the Hurricanes. For example, Bomb carrying ability was nearly quadrupled from 500 kg in the B-version to 1,800 kg (max load) in the D-version. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason was the aircraft design itself. It was designed to be a rigged dive bomber, and increase in speed would've done it no good (it is to be noted that the fixed landing gear added a lot of drag, though it was study enough to mount a cannon) and it had limited maneuverability at the best of times when loaded (though it had good turn performance at low altitudes). The airframe had reached its limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason the Stuka served till the end of the war though its limitations had become apparent by the Battle of Britan was simply because no better replacements were avilable (though the process started in early 1940's), though the &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_190#Ground_attack_versions&quot; rel=&quot;noreferrer&quot;&gt;Focke Wulf 190&lt;/a&gt; took over some of the duties of Ju-87.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-25T08:29:32.250" LastActivityDate="2015-09-25T08:29:32.250" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21200" PostTypeId="2" ParentId="21197" CreationDate="2015-09-24T12:55:39.047" Score="18" Body="&lt;p&gt;The engine was replaced when newer versions were introduced: The first production model (Ju-87&amp;nbsp;A) used a &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Jumo_210&quot; rel=&quot;noreferrer&quot;&gt;Jumo 210&lt;/a&gt; with 690&amp;nbsp;HP takeoff power. This was raised in the B version to 1200&amp;nbsp;HP by switching to the improved &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Jumo_211&quot; rel=&quot;noreferrer&quot;&gt;Jumo 211&lt;/a&gt;. From 1941 the D version with the more powerful Jumo 211&amp;nbsp;J (1420&amp;nbsp;HP) was introduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that is all besides the point. No powerplant would had made it faster than the contemporary fighters, not even a jet engine. The design placed ruggedness first, and as a consequence had a fixed landing gear which could be used on unprepared fields. The airplane had a lower wing loading than fighters, had the very effective Junkers Doppelflügel (offset flaps) and could turn much better, so it was not easy to shoot down. The downside was an inherently higher drag which could not be overcome with a bigger engine (which would had made the aircraft heavier).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dys8L.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dys8L.jpg&quot; alt=&quot;Detail of the Ju-87 wing flaps&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detail of the Ju-87 wing flaps from the operating manual (picture &lt;a href=&quot;http://www.rc-network.de/forum/attachment.php?attachmentid=72180&amp;amp;d=1177566185&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). By using those, a Ju-87 could fly much slower and turn much tighter than contemporary fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea was to optimize the Ju-87 for ground support and let the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_109&quot; rel=&quot;noreferrer&quot;&gt;Bf-109&lt;/a&gt;s and &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_190&quot; rel=&quot;noreferrer&quot;&gt;Fw-190&lt;/a&gt;s take care of the fighters. This worked well during the Blitzkrieg of 1940 and on the Eastern Front when the airplane was used as designed. This is the same strategy the US Air Force uses for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II&quot; rel=&quot;noreferrer&quot;&gt;Fairchild A-10&lt;/a&gt; attack airplane. Being designed as a dive bomber, the Ju-87 airframe was very sturdy and robust. There are many stories of Ju-87 pilots returning with heavily damaged planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iujwV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iujwV.jpg&quot; alt=&quot;Battle damage on a Ju-87&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Battle damage on a Ju-87 (picture &lt;a href=&quot;http://www.ww2incolor.com/forum/showthread.php/4184-The-Junkers-Ju-87-Stuka-topic/page3&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DQJQz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DQJQz.jpg&quot; alt=&quot;Damaged Ju-87 wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Damaged Ju-87 wing (picture &lt;a href=&quot;http://www.ww2incolor.com/forum/showthread.php/4184-The-Junkers-Ju-87-Stuka-topic/page3&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially &lt;a href=&quot;https://en.wikipedia.org/wiki/Hans-Ulrich_Rudel&quot; rel=&quot;noreferrer&quot;&gt;Hans-Ulrich Rudel&lt;/a&gt; used the Ju-87 with great effect. If you read his &lt;a href=&quot;http://www.amazon.de/Stuka-Pilot-Memoirs-Hans-Ulrich-Rudel/dp/1847680003&quot; rel=&quot;noreferrer&quot;&gt;memoirs (Amazon link)&lt;/a&gt;, you will learn that he once was surprised by fog and could not fly back to his base. So he landed on a road and taxied the 70 km back. He almost made it back to base; only an impassable railroad crossing could stop him from taxiing all the way home.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At several occasions, he landed next to a shot-down Ju-87 and took the crew onboard. Try that with a Hurricane or a Spitfire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1944 he was chased by a Russian fighter pilot. His observer, sitting in the rear seat, facing backwards, could tell him every time what his opponent was up to, so he could evade the attacks successfully, flying close to the ground and at minimum speed, flaps down. Suddenly, the Russian fighter was gone: Unable to fly as slowly as the Ju-87, he had stalled and crashed. Later, Rudel learned that this had been one of the most highly decorated Russian aces. The Ju-87 with a skilled crew was more than a match for him.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the war, he consulted Fairchild during the development of the A-10. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-25T09:44:20.973" LastActivityDate="2015-09-25T09:44:20.973" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21201" PostTypeId="2" ParentId="21198" CreationDate="2015-09-24T13:48:11.083" Score="6" Body="&lt;p&gt;I don't know about a &quot;long history&quot;, but the Australian aviation authorities (Jabiru is an Australian company) did introduce &lt;a href=&quot;https://www.casa.gov.au/standard-page/precautions-jabiru-powered-aircraft-0?WCMS%3ASTANDARD%3A%3Apc=PC_102352&quot; rel=&quot;nofollow&quot;&gt;operating restrictions&lt;/a&gt; because of what they considered to be a high rate of engine failures. Note that Jabiru makes their own engines, unlike most other aircraft manufacturers, and as well as using them in their own aircraft they sell them for use in &lt;a href=&quot;https://en.wikipedia.org/wiki/Light-sport_aircraft&quot; rel=&quot;nofollow&quot;&gt;LSAs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.casa.gov.au/&quot; rel=&quot;nofollow&quot;&gt;CASA&lt;/a&gt; mentioned 45 incidents in one year:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These precautionary limitations follow a high number of Jabiru engine&#xA;  failures and power loss incidents, some of which resulted in aircraft&#xA;  forced landings.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;More than 45 Jabiru engine failures or in-flight engine incidents have&#xA;  been reported in 2014, with CASA recently becoming aware of incidents&#xA;  in previous years.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Problems with Jabiru engines include failures of through bolts,&#xA;  flywheel bolts and valve train assemblies, as well as cylinder&#xA;  cracking.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The failures affect a range of Jabiru engine models and have occurred&#xA;  in aircraft used in different flying activities, although many have&#xA;  been reported in aircraft used for flying training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;By itself, the number 45 doesn't mean much without considering more information about the number of aircraft, the number of hours flown, maintenance performed etc. and Wikipedia says that Jabiru didn't agree with CASA's decision (which isn't surprising). But presumably CASA did think about those things and still decided that there should be restrictions in place.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-09-24T15:12:50.263" LastActivityDate="2015-09-24T15:12:50.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21202" PostTypeId="1" AcceptedAnswerId="21207" CreationDate="2015-09-24T14:47:29.980" Score="5" ViewCount="509" Body="&lt;p&gt;Are the computer screens used by ATC generic across different countries? I.e., do ATCs around the world simply purchase the same software from a few companies, or do each of them develop their own system and end up with different user interfaces?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an analogy of aircrafts, most of the controls and instruments are universal across pretty much all aircrafts, be it Cessna, Piper, Airbus, Boeing, CRJ etc. Any trained pilot would likely recognize the important controls (e.g. throttle, flap lever, attitude indicator) right away; certain colors and symbols are also expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this the same for the computer systems used by ATC? E.g. if a controller from the US goes to Australia, is he expected to understand and know how to operate the equipment right away?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-09-24T14:54:30.897" LastActivityDate="2015-09-24T20:26:40.187" Title="Is the user interface design of ATC equipment generic across countries?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21203" PostTypeId="2" ParentId="21202" CreationDate="2015-09-24T14:58:43.150" Score="1" Body="&lt;p&gt;Like anything it varies from place to place and even within countries. This is mainly because not every ATC facility is built at the same time. You are more likely to find equipment from the same era as the building or the last time it had a major over haul. For what its worth you are correct that there are only a handful of companies making ATC equipment (radar etc.) but through out the course of time the models vary. Some less economically profitable countries may even buy units second hand from others. In the end of the day Radar is Radar and most if not all radar screens will look at least generally similar.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FWIW airplanes have highly varying control designs. While Boeing employs a yoke Airbus is partial to the side stick. Cessna's typically use push/pull throttles that are rod style as well as electric flaps while Piper uses lever throttles and Johnson bar flaps, Older Mooneys even sport johnson bar landing gear... So not all planes are made the same shy of the instruments which are generally the same aside from older Russian attitude indicators which appear reversed from the ones typically found in other planes. I will agree that any pilot should be able to identify the controls they are of highly varying design.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-09-24T14:58:43.150" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21204" PostTypeId="2" ParentId="21171" CreationDate="2015-09-24T17:25:33.280" Score="5" Body="&lt;p&gt;Short answer: &lt;strong&gt;no&lt;/strong&gt;, none of what you describe is possible with current jet engines. You need more fuel &lt;strong&gt;because&lt;/strong&gt; the angle of attack for your prop is increased, not the other way round.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's first go into some (simplified) detail how the turboprop works. A turboprop is basically a gas turbine engine with a propeller stuck on the axle. The propeller is the bit that converts the torque and rpm of the engine shaft into a forward thrust. The amount of forwards force is determined by RPM and blade pitch. This means that, even though you're at high RPM, you can 'feather' your propeller so that it doesn't produce any forward thrust (blades flat). At the same RPM, you can just put your blades so that they produce a lot of thrust. Of course, this comes at the cost of increased drag, so the engine has to 'work harder' to maintain RPM. This, in turn, is achieved by injecting more fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to a turbojet. For a turbojet, the thing that produces thrust is exhaust gas going backwards &lt;em&gt;real fast&lt;/em&gt;. This is achieved by burning fuel so that the gas gets hot and expands, so that it wants to get out of there as fast as possible. For this, a jet engine needs &lt;strong&gt;a lot of air&lt;/strong&gt;. It sucks in this air by a series of compressors at the front of the engine. Then, some fuel is injected, and after that there are some turbines that make sure the compressors can, and after that there's a nozzle that converts the leftover energy into backwards gas velocity. Now, we want to increase the thrust. This means that gas has to get out of the back faster. Since the nozzle is generally fixed, this means that you just have to get &lt;strong&gt;more&lt;/strong&gt; air out of the back (just like a garden hose with the tap half open or full open). This means that we'll have to suck in some more air from the front, burn some more fuel to make sure the engine keeps spinning, and more air will come out of the back. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simply increasing the fuel flow doesn't work. Jet engines operate 'lean' (more air than necessary), and the extra fuel you suddenly inject will burn up with all the excess air, which might blow up your engine. If your engine doesn't blow up, you're left with too little air to burn all the fuel, and you'll get a lot of nasty things like soot, carbon monoxide and unburnt fuel coming out of your exhaust. This means you just inject some extra fuel, wait for the engines to 'spool up' so they suck in more air, and like that gradually increase your engine RPM and linked to that the gas velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two things remain: why use fixed nozzles? This is because physics dictate that, for engines to be efficient, the exhaust velocity needs to be as high as possible; in practice, the exhaust velocity will be as close as possible to the speed of sound in the hot flue gas. Using a variable nozzle would mean that your engine never works efficiently at half power. Furthermore, it adds complexity, weight and thus costs more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing: I discussed turbojets, not turbofans. In theory, one could have variable blade pitch on a jet engine. However, remember that the fan is not just for thrust (even though high-bypass engines are generally more efficient), but also to make sure enough air enters the compressors; 'feathering' them would mean that your engine might not get enough air. However, your engine would need a lot of air, because it needs to operate very lean to make sure it can handle the extra fuel flow for when you increase the blade pitch. Furthermore, a variable pitch on all blades would mean a lot of complex engineering, which would make the engine a lot heavier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long story short: one &lt;em&gt;could&lt;/em&gt; design jet engines with variable pitch, but the above wall of text is only the beginning of why that is an engineering nightmare. Without variable blade pitch or nozzles.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2015-09-24T17:25:33.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21205" PostTypeId="2" ParentId="21188" CreationDate="2015-09-24T17:41:13.287" Score="17" Body="&lt;p&gt;In addition to @Airsick's excellent answer, some coaxial helicopters, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gyrodyne_RON_Rotorcycle&quot; rel=&quot;noreferrer&quot;&gt;Gyrodyne Rotorcycle&lt;/a&gt;, use tip brakes to achieve yaw authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below are a couple examples of tip brakes, found at &lt;a href=&quot;http://www.gyrodynehelicopters.com/xron_history.htm&quot; rel=&quot;noreferrer&quot;&gt;this website&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eeRdb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eeRdb.jpg&quot; alt=&quot;http://www.gyrodynehelicopters.com/images/GCA_Rotor_Blade_PROBE_TYPE_Tip_Brake-ProgressivelyL5.jpg&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NFX3Z.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NFX3Z.jpg&quot; alt=&quot;http://www.gyrodynehelicopters.com/images/QH-50_Rotor_Blade__Flag-Type_Tip_Brake_Open.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tip brake is a drag-inducing device on the end of the blade, that can be extended or retracted to increase or decrease drag.  To yaw in one direction, the tip brakes would be extended on one set of blades, but not the other, generating a net torque due to increased drag in that rotor.&lt;/p&gt;&#xA;" OwnerUserId="7165" LastActivityDate="2015-09-24T17:41:13.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21207" PostTypeId="2" ParentId="21202" CreationDate="2015-09-24T20:26:40.187" Score="5" Body="&lt;p&gt;Most ATC software systems are developed by a few large companies. Companies that produce such software include Lockheed Martin, Thales, Raytheon, Indra, Comsoft, Adacel (and maybe a few others). It's not a big market since there are only a limited number of customers (countries) and safety critical software is very expensive to develop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One interesting offering is the &lt;a href=&quot;http://www.albatross.aero/&quot;&gt;Albatross&lt;/a&gt; open source ATC software. This isn't a complete system (yet?) but some parts are available now. I'm not sure whether this software is actually used in operations anywhere at this point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most ATC providers (which are usually run or owned by their government, though not always) do not do their own software development. They buy a system from one of the established vendors, who may do some amount of customisation work ranging from none to extensive, perhaps with a support contract for future fixes or enhancements. There are a few exceptions though, for example Airways New Zealand uses software originally developed by a large vendor but also has an in-house software development group who maintains, enhances, and extends the existing software.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each system has the same general operating concept - an ASD (Air Situation Display) which shows the locations of aircraft, plus auxiliary windows that may contain all kinds of other things used for communication and coordination. Like any sophisticated computer software, the general idea of two different systems might appear the same, but be completely different to actually operate (think of Photoshop vs. Gimp, or Microsoft Word vs. Apple Pages). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A qualified controller from the US would not be expected to be able to operate in Australia straight away. Not only will the software be different (different mouse clicks, or different key commands), but also the rules of air traffic control can be different between countries. Furthermore, a controller must become familiar with the local airspace and operating procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, the general skills of air traffic controllers &lt;em&gt;are&lt;/em&gt; portable between countries. On moving from one country to another, a controller would be expected to go through a certain amount of training in their new country, which could range from brief familiarisation to more rigorous retraining. &lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-09-24T20:26:40.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21208" PostTypeId="2" ParentId="21188" CreationDate="2015-09-24T21:21:23.443" Score="3" Body="&lt;p&gt;In simple terms, you increase the drag on the rotors going one way, and reduce it on the rotors going the other way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally you increase the pitch of one rotor (meaning more lift and more drag), and decrease it on the other (meaning less lift and less drag). The lift balances out, but the difference in drag causes yaw.&lt;/p&gt;&#xA;" OwnerUserId="2483" LastActivityDate="2015-09-24T21:21:23.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21211" PostTypeId="2" ParentId="19590" CreationDate="2015-09-24T21:35:47.543" Score="0" Body="&lt;p&gt;With an EASA PPL(A) you can fly single engine piston aircraft, for example the Cessna 172 or the tiger moth&lt;/p&gt;&#xA;" OwnerUserId="11349" LastActivityDate="2015-09-24T21:35:47.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21212" PostTypeId="1" AcceptedAnswerId="21213" CreationDate="2015-09-24T21:41:38.050" Score="11" ViewCount="993" Body="&lt;p&gt;I know that aircraft generate wake turbulence and wingtip vortices, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/11916/what-type-of-commercial-aircrafts-generate-strong-wake-turbulence&quot;&gt;the strength of those phenomena are related to the size of the aircraft&lt;/a&gt;, but how powerful are wingtip vortices in terms a non-pilot would understand?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if a human were standing inside of a wingtip vortex would it have the strength to knock them off their feet?  If the wingtip vortex were turned vertical like a tornado would it be an EF1, or an EF5?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-25T11:36:32.340" Title="How &quot;powerful&quot; is a wing tip vortex?" Tags="&lt;wing-tip-vortex&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21213" PostTypeId="2" ParentId="21212" CreationDate="2015-09-25T01:46:09.850" Score="10" Body="&lt;p&gt;If we're talking about large aircraft the answer is &lt;em&gt;Powerful enough that you want to stay out of them.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I refer you to &lt;a href=&quot;https://youtu.be/WXjbVLgK-fU?t=8m52s&quot;&gt;this delightful FAA video&lt;/a&gt; in which a Cessna (looks like a 172) was flown into the wake of a C-5 Galaxy. The Cessna was rolled through 360 degrees by the vortex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-14-DFRC.html&quot;&gt;NASA research&lt;/a&gt; has shown that the rotational speed of wake vortices can exceed 150 miles per hour (130 knots).&lt;br&gt;&#xA;While the &lt;a href=&quot;https://en.wikipedia.org/wiki/Enhanced_Fujita_scale&quot;&gt;Enhanced Fujita Scale&lt;/a&gt; rates tornadoes based on damage a 150 mile per hour wind speed is in the range estimated for an EF3 tornado (&quot;Severe Damage&quot;, defined as &lt;em&gt;Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations are badly damaged.&lt;/em&gt;) - This should reduce your desire to be anywhere near the wake vortex of a large aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If we're talking about smaller aircraft (say two Cessnas flying in trail, and the trailing aircraft somehow gets below the lead) it's strong enough to be unpleasant - the wake from the leading aircraft will shake and rock the wings of the trailing aircraft, but it &lt;em&gt;probably&lt;/em&gt; won't flip the trailing aircraft over.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many pilots are familiar with encountering their own wake at some point in flight training: &lt;a href=&quot;http://www.avweb.com/news/airman/183095-1.html&quot;&gt;It can happen when practicing steep turns in calm air&lt;/a&gt;.&lt;br&gt;&#xA;If the weather and timing of the turn are &quot;just right&quot; and you produced a circle rather than an oval yo will hit the descending wake from your outside wing as you roll level at the 360 degree mark. This produces a slight &quot;bump&quot; at the end of the maneuver (&lt;a href=&quot;https://youtu.be/t-NJAoCAqqY&quot;&gt;visible in this video&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-09-25T01:52:09.717" LastActivityDate="2015-09-25T01:52:09.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21216" PostTypeId="1" AcceptedAnswerId="21225" CreationDate="2015-09-25T04:33:03.073" Score="5" ViewCount="1602" Body="&lt;p&gt;I'm wondering if radio waves are reflected by the sea. If so then the usual radar altimeter would work. If not, then is there any other fallback besides barometric altimeter?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;noreferrer&quot;&gt;wiki article&lt;/a&gt;, for some reason radar altimeter uses &lt;strong&gt;radio waves&lt;/strong&gt; (instead of microwaves like usual radar). This is why I put in the radio tag.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2015-09-25T07:05:12.683" Title="Does radar altimeter work over the ocean?" Tags="&lt;radio&gt;&lt;altimeter&gt;&lt;oceanic&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21219" PostTypeId="1" AcceptedAnswerId="21230" CreationDate="2015-09-25T05:55:13.040" Score="20" ViewCount="15901" Body="&lt;p&gt;I have seen this in a picture once online and thought it was very strange and wondered about the formation of this vortex and how could it happen.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NUQCP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NUQCP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://cerebrovortex.files.wordpress.com/2013/12/vortex-water-4237677428.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not everyday do you see this happening. So how does this happen, and why does it not happen very often?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/u9AZW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/u9AZW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://rob.com/pix/var/albums/oops/c17vortex.jpg?m=1289692857&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another picture of this strange occurrence. This generally happens with thrust reversal.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="4197" LastEditDate="2015-09-25T07:05:37.967" LastActivityDate="2019-08-19T17:18:11.227" Title="How does this vortex form inside a jet engine?" Tags="&lt;turbofan&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21221" PostTypeId="1" AcceptedAnswerId="21228" CreationDate="2015-09-25T06:03:37.797" Score="2" ViewCount="139" Body="&lt;p&gt;The first flight of a new aircraft is a major aviation milestone for the company and the industry.  What departments or organizations (within a parent organization), and what individuals, are invited to the pre-flight review of a First Flight of a new aircraft?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What kind of stake holders are invited?&lt;/li&gt;&#xA;&lt;li&gt;How many Technical guys are invited?&lt;/li&gt;&#xA;&lt;li&gt;Is there any regulation by FAA to include a particular parties?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="1696" LastEditDate="2018-01-04T19:11:31.607" LastActivityDate="2018-01-04T19:11:31.607" Title="Which organizations and individuals are invited for a review before the first flight of a new aircraft?" Tags="&lt;aircraft-certification&gt;&lt;flight-testing&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-09-25T09:06:54.747" ContentLicense="CC BY-SA 3.0" />
  <row Id="21222" PostTypeId="1" CreationDate="2015-09-25T06:15:35.910" Score="18" ViewCount="7560" Body="&lt;p&gt;From my &lt;a href=&quot;https://aviation.stackexchange.com/questions/19609/has-there-ever-been-a-diesel-electric-helicopter&quot;&gt;related question&lt;/a&gt; comes this idea of electrically controlled blade pitch in helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Control linkages in helicopter rotors seem to be pretty complex. This surely incurs a lot of friction, especially if you realize that blades have to &quot;flap&quot; back and forth as they rotate around (in order to compensate for retreating blade stall and/or dissymmetry of lift during forward flight). So the swashplate and linkages must surely undergo a lot of friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ao8JO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ao8JO.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So why not replace all this with electric motors that control blade pitch?&lt;/strong&gt; They would be small, inside the rod connecting the blade to the hub. No need for any pitch control to be mechanically connected to any other blade(s), so no friction. A computer would control what the pitch should be given the blade's position during its rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This does &lt;strong&gt;not&lt;/strong&gt; mean the main rotor has to be electrically driven. The turboshaft engines can drive the main rotors mechanically as normal. But there would be an electric generator for the blade pitch motors. Note: I'm pretty sure &lt;strong&gt;there's already an electric generator&lt;/strong&gt; on these engines as the computers and radars and stuff have to get their electric power from somewhere.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2021-05-10T14:08:04.637" Title="In helicopters, why not have electric motors controlling blade pitch?" Tags="&lt;helicopter&gt;&lt;engine&gt;&lt;electric-engine&gt;&lt;blade&gt;" AnswerCount="7" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21223" PostTypeId="1" AcceptedAnswerId="21227" CreationDate="2015-09-25T06:45:36.293" Score="1" ViewCount="1525" Body="&lt;p&gt;I have seen some MEMS micro engines and some micro turbines and I would guess they can be attached to some payload to fly. Is it possible for commercial/military radars to detect those micro flying devices?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5517" LastEditDate="2016-07-05T12:48:49.780" LastActivityDate="2016-07-05T12:48:49.780" Title="Can radar detect a small flying device with MEMS microengines?" Tags="&lt;radar&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21225" PostTypeId="2" ParentId="21216" CreationDate="2015-09-25T07:05:12.683" Score="7" Body="&lt;p&gt;Yes.  In the Navy, our primary source of altitude indication under 5,000ft is the radar altimeter.  The AGL over the ocean conveniently also happens to be the MSL as well.&lt;/p&gt;&#xA;" OwnerUserId="4215" LastActivityDate="2015-09-25T07:05:12.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21226" PostTypeId="2" ParentId="21222" CreationDate="2015-09-25T07:14:41.963" Score="24" Body="&lt;p&gt;How would you communicate with (and power) these motors?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main rotor is spinning constantly - Wires won't work, they would wrap around the shaft and be shredded. A slip ring and brushes (&lt;a href=&quot;http://www.airmasterpropellers.com/products/type/view/id/20/ap332-system-overview&quot;&gt;as used in some electically-actuated propellers&lt;/a&gt;) would work, but would also wear away quickly and require frequent maintenance as losing control of a helicopter's main rotor blade pitch is a much more serious situation than losing control of a fixed-wing aircraft's propeller pitch (I believe &lt;a href=&quot;https://youtu.be/G1IMM5XOwaM?t=1m14s&quot;&gt;this captures the consequences pretty well&lt;/a&gt;).&lt;br&gt;&#xA;Because of the rotor speed balance is critical, so any motors, brushes, etc. would need to be balanced around the rotor hub (either by duplicating the equipment, which also provides redundancy, or by adding dummy weight) - get it wrong and the rotor starts vibrating and may come apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The motor would also have to be &lt;em&gt;constantly moving&lt;/em&gt;: &lt;a href=&quot;https://www.youtube.com/watch?v=83h6QK-oJ4M&quot;&gt;The swashplate adjusts blade pitch through the full 360 degrees of rotation&lt;/a&gt;, smoothly changing the pitch of each rotor blade as they rotate. Duplicating this would require the motor(s) to make constant adjustments as the rotor turns, moving and reversing very rapidly). The level of precision required and the forces involved would likely require high-torque stepper motors and a computerized control system of some kind would be needed to drive them and make the necessary blade pitch adjustments at &quot;rotor speed&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So far the motorized solution has added at least one motor, a slip ring &amp;amp; brush system to communicate with it, and a fly-by-wire computer to read the flight control positions and appropriately adjust the blade pitch through 360 degrees of rotation (at whatever speed the rotor is operating).&lt;br&gt;&#xA;That is already a &lt;em&gt;lot&lt;/em&gt; of complexity and a substantially increased chance of failure versus the (relatively) simple mechanical solution of a swash plate, and I'm not even going out of my way to think of failure modes (actual engineers designing these things are far more paranoid, and could probably imagine all sorts of failure scenarios which eventually result in a helicopter plunging to the ground).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-25T07:14:41.963" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21227" PostTypeId="2" ParentId="21223" CreationDate="2015-09-25T07:33:32.107" Score="6" Body="&lt;p&gt;Obviously the MEMS engine itself is not going to be detected: they're only a few millimetres across. The question entirely depends on what you attach it to.&#xA;Conventional radars have trouble detecting UAVs less than a couple of metres long, and replacing their power plants with micro turbines won't change that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My neighbours at &lt;a href=&quot;http://www.aveillant.com/&quot;&gt;Aveillant&lt;/a&gt; already have a holographic radar system that can detect smaller targets such as UAVs more accurately. Again, changing the power plant technology won't change that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Micro-turbines are not intended to replace propulsion systems, but to replace batteries, allowing them to use denser hydrogen, methane, or methanol fuel. As far as I've been able to find, they don't produce break-even power yet, but it's envisioned that they will become commercially relevant once they can produce more than 10 W (about .01 hp), in a few years' time. For comparison, a current, small, military UAV might generate tens of horsepower, and some experimental super-lightweight UAVs need as little as 5 hp, but with no payload or cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TL;DR: (a) MEMS turbines aren't going to be relevant for UAVs for some years, and they'll have to be much bigger than they are now; (b) replacing the power plant won't make much difference to the radar signature.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-09-25T07:33:32.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21228" PostTypeId="2" ParentId="21221" CreationDate="2015-09-25T07:40:54.830" Score="6" Body="&lt;p&gt;The level of contribution is your potential contribution to the particular flight test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several levels:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Who gets a place in the aircraft?&lt;/strong&gt; This should be test pilot(s) and maybe an engineer or two if the aircraft has enough space to carry them.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Who gets a place in the control room?&lt;/strong&gt; This is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_test_engineer&quot; rel=&quot;noreferrer&quot;&gt;flight test engineer&lt;/a&gt; and systems engineers (experts for the engine, the control system, the landing gear and so on), also engineers familiar with the aerodynamics and flight mechanics of the plane. Generally, the number of people in the room should be kept small.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Who gets a place at the ceremony and press conference afterwards?&lt;/strong&gt; Now only the test pilot is invited, and maybe the flight test engineer and the development project leader, but otherwise you will find mostly board members and PR people at the press conference. The engineers will be busy clearing the buffet at this time, anyway.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The responsibility to select who will get into the control room rests primarily with the flight test engineer and the test pilot. However, the whole aircraft development will already be observed by the FAA. From the &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/design_approvals/media/CPI_guide_II.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA and Industry Guide to Aircraft Certification&lt;/a&gt; about the implementation of the planned flight test:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During this Phase the Applicant and FAA work closely in managing, refining, and achieving their agreed PSCP to ensure that all agreed upon product specific certification requirements are met.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;PSCP = Project Specific Certification Plan &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, FAA engineers are reviewing the planning, but do not get into the details such as who exactly will participate in the first flight. The company developing the aircraft prepares a plan and FAA will approve it without much hassle if the company has a record of conducting flight tests. If the company is a startup, however, closer scrutiny must be expected.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-09-25T07:40:54.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21229" PostTypeId="2" ParentId="21219" CreationDate="2015-09-25T08:25:00.107" Score="12" Body="&lt;p&gt;The inlet vortices shown form in the case of turbine engines and in propellers during operation near ground where there is a little or no crosswind. In standard atmospheric conditions, the vortex is invisible; however, with enough humidity, condensation occurs inside the vortex core (as temperature falls below the dew point temperature), and the vortex becomes invisible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T2QSs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T2QSs.jpg&quot; alt=&quot;C 130 propeller vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: wpi.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the engine is started, the engine ingests air whose cross sectional area is greater than the engine frontal area. Near ground, this includes ground as well and induces a flow there. As air nears the engine, it is accelerated and if some amount of vorticity is already present, it forms an inlet vortex, which become visible under some conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E8X6T.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E8X6T.png&quot; alt=&quot;Ground Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from patent application of &lt;em&gt;Active ground vortex suppression system for an aircraft engine&lt;/em&gt; EP 1413721 B1&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inlet vortex forms between the engine (or propeller) and a stagnation point on the ground. This is usually not formed far away from the ground as the vortex lines cannot start or end in a fluid according to &lt;a href=&quot;https://en.wikipedia.org/wiki/Helmholtz%27s_theorems&quot; rel=&quot;noreferrer&quot;&gt;Helmholtz's theorems&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, one end of the vortex is attached to the engine (or propeller) and the other end extends and attaches itself to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two mechanisms for this inlet formation have been proposed,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ambient vorticity (upstream) is amplified by the engine and stretched and drawn into the engine.&lt;/li&gt;&#xA;&lt;li&gt;Without upstream vorticity (i.e. in an irrotational flow), the vortices form in the presence of crosswind. In case of high crosswinds, the inlet vortex is bent around the inlet and for very high crosswinds, the vortex does not form at all.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The study of engine inlet vortex formation is an important research topic as the inlet vortex can cause a number of problems such as,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FOD ingestion&lt;/li&gt;&#xA;&lt;li&gt;Compressor surge &lt;/li&gt;&#xA;&lt;li&gt;If there is a crosswind, the inlet vortex can cause separation in the inlet lip region, causing performance losses.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the inlet vortices to form, there should be usually some sort of rotation flow in the far field, which is usually given by the crosswind as it interacts with the fuselage; In case there is no crosswind, inlet vortices still form, though a pair are formed, which rotate in &lt;em&gt;opposite&lt;/em&gt; directions. This is probably the vortices in simulation which @sweber showed in answer..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2xzGC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2xzGC.jpg&quot; alt=&quot;Twin inlet vortices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: gallery.ensight.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason for the presence of vortices when reverse thrusters are engaged is that they cause air flow with sufficient vorticity in the vicinity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;em&gt;An Experimental Study of the Formation and Unsteady Characteristics of Inlet Vortices&lt;/em&gt; by Wang and Gursul, accessed via enu.kz&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The vortex suppression system in the patent described above injects fluid near the inlet, which disrupts the flow structure of a ground vortex, thus mitigating ground vortex. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qnBAj.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qnBAj.png&quot; alt=&quot;Vortex mitigation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from patent application of &lt;em&gt;Active ground vortex suppression system for an aircraft engine&lt;/em&gt; EP 1413721 B1&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-25T14:14:54.017" LastActivityDate="2015-09-25T14:14:54.017" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21230" PostTypeId="2" ParentId="21219" CreationDate="2015-09-25T08:54:24.477" Score="17" Body="&lt;p&gt;Whenever there is under-pressure in air, the air flows along the gradient of this under-pressure, i.e. into the direction of the source of the under-pressure. (In first order.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's a wall (or the ground) in the way, air will flow along the surface of this obstacle and will change its direction at some point, as shown in this sketch:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ui1pe.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ui1pe.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, imagine the whole air around the engine is rotating slowly for some reason around the symmetry axis in the sketch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From physics, you may know the conservation of momentum, or in this case, of angular momentum. It says that the product of distance to rotation axis times RPM of this rotation is constant for a certain particle. If a particle reduces its distance to the axis, its RPM increases.&lt;br&gt;&#xA;This is like the spinning ice skater, who rotates faster when he pulls his arms to his body (to the axis).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This law also applies to packets of air, which are sucked to the axis, though internal friction brakes the air to some extent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fast rotating air near the axis encounters a centrifugal force, i.e. the air is pulled away from the axis, forming a region of strong under-pressure. In this region, the air expands and so, cools down. This can cause condensation of water, if the humidity of the air is high enough. And that's what you can see on your pictures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's still one question unanswered: I wrote, this happens if the surrounding air is rotating slowly. This usually happens, because the wind is deflected from the aircraft itself, which means it changes its direction, which is some kind of rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And of course, a strong, non-uniform air flow from the rear, as generated by the reverse thrusters, can cause more / stronger rotating air, which results into stronger vertices. So, it's no wonder when they appear (or better: become more visible) in this case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a nice picture of a simulation, which also shows that the fuselage can be the wall where the vortex is created.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JqwYJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JqwYJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Source: &lt;a href=&quot;http://gallery.ensight.com/keyword/aerospace/&quot; rel=&quot;noreferrer&quot;&gt;http://gallery.ensight.com&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems the wind comes from the camera position, or a bit more right of it. It gets deflected by the fuselage and flows along it, which explains the straight lines coming from the rear and the curved ones coming from the front left of the aircraft. If you imagine the air flow along / under the fuselage, you may also understand why the two vertices are rotating in different orientations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the strong under-pressure inside the vortex, it may also suck in dust or even larger objects, which can damage the engine. For aircraft landing on unpaved airfields, &lt;em&gt;unpaved strip kits&lt;/em&gt; may be available, which can contain a vortex dissipator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oycDA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oycDA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Source: &lt;a href=&quot;http://www.b737.org.uk/unpavedstripkit.htm&quot; rel=&quot;noreferrer&quot;&gt;http://www.b737.org.uk&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a nozzle blowing bleed air into the region where vortices could apper, reducing the under-pressure and so the risk of ingesting objects from the ground.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Notes:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You can see something similar in the sink of your bathtub. As soon as there is a little rotation, it is amplified above the sink, the centrifugal force pushes the water aside, and forms this fast rotating vortex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tornado is a giant version of an inlet vortex. The air is moving along ground over far distances, until it moves upwards at some point, and a slight rotation leads to this fast rotating hose sticking to the ground and sucking in everything due to the strong under-pressure inside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a bit off-topic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes, you can see vortices at the wing tips or at the edges of engaged flaps of aircraft flying through humid air. The reason is similar: The air is put into rotation due to the higher pressure below and the lower above the wings. (But that's not exactly the same as inlet vortices.) And sometimes, you also see fog forming above the wing just because of the under-pressure.&lt;br&gt;&#xA;On this picture, you see both, and may imagine the rotation for the second vortex from the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qccDf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qccDf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Source: &lt;a href=&quot;http://avioners.net/wp-content/uploads/blogger/-oNkgIgSJCMA/UMZ-nXMWpAI/AAAAAAAANcg/c3MBXbSTw74/s1600/md11_vortex.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://avioners.net&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-09-25T10:50:34.563" LastActivityDate="2015-09-25T10:50:34.563" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21231" PostTypeId="2" ParentId="19102" CreationDate="2015-09-25T09:53:32.930" Score="13" Body="&lt;p&gt;I don't know, but ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the &lt;a href=&quot;http://www.iata.org/services/Documents/codes-designator-form.pdf&quot;&gt;IATA application form&lt;/a&gt; you will see there is nowhere for the airline to indicate the code it would like to receive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine many new airlines might indicate a preference in an accompanying letter (e.g. they would like a code starting with a specific letter)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the allocated codes you can see that, initially, some attempt was made by IATA to make the two-character codes mnemonic &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;AA = American Airlines&#xA;BA = British Airways&#xA;etc&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;However if JB was already allocated, it is reasonable that the IATA&#xA;staff would look for an available code starting with either J or B.&#xA;Since the Blue of JetBlue is more distinguishing than the Jet part of the name, the IATA employee may have started with B and noticed that the following were already &lt;a href=&quot;http://www.iata.org/publications/Pages/code-search.aspx&quot;&gt;allocated&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;B1 Bravo Passenger Solution Pte., Ltd. &#xA;B2 Belavia &#xA;B3 Bhutan Airlines dba Tashi Air Pvt L &#xA;B4 ZanAir Limited &#xA;B5 East African Safari Air Express Ltd.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;(note I have not checked dates these codes were allocated but the hypothesis seems plausible to me)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last two are puzzling but perhaps they changed their names (perhaps as part of a takeover, merger or split). Airline codes do get reused. For example, B5 was used by FlightLine before it went out of business.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then B6 would be the next available code.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-09-25T10:21:24.433" LastActivityDate="2015-09-25T10:21:24.433" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21232" PostTypeId="2" ParentId="21222" CreationDate="2015-09-25T10:21:52.647" Score="15" Body="&lt;p&gt;Because it would be too complicated (and failure prone) compared to the present system and would offer no great advantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, for all the complexity in the helicopter upper controls, the principle is pretty simple- Align the rotor plane with the (rotating) swash plate, and tilt (or rise) it according to requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gWjAR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gWjAR.jpg&quot; alt=&quot;Helicopter upper controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: helistart.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This system is used in almost all helicopters, and have operated for millions of flight hours under a variety of conditions and has proven itself over a wide range of helicopter weights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to replace it, the electric motor system should have the following characteristics.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The electric motor, if used should be highly robust, with extremely low failure rate as it (failure of any one) would jeopardize flight safety. Also, it should be able to deliver significant changes in torque in a rapid manner.&lt;/li&gt;&#xA;&lt;li&gt;The power supply to the motor would be critical and the only thing I could think of is the slip-ring system. This would require frequent inspection as power supply (and signal transmission) is absolutely critical for operation. The power supply required would make the electrical system of the helicopter heavier and more complicated (due to redundancy).    &lt;/li&gt;&#xA;&lt;li&gt;New control algorithms and a flight computer (a fly-by-wire system) has to be developed for this system as it is completely incompatible with the present ones and there is no way to directly transmit the pilot control inputs to the rotor blades as it is done at present. I'm not sure if anyone is going to develop a complicated system (it has to be operational at every point of the rotor rotation as pitch is varying constantly) to replace a system that has been operating well.&lt;/li&gt;&#xA;&lt;li&gt;The components should be balanced (i.e. their weights should be balanced) across all the bales as it would lead to vibrations otherwise.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The rotor would have to be hinged at some point anyway. Then the question becomes how to transmit the rotary motion from the hub side to the blade side. This can be done either by&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pitch link, which is practically the same as a mechanical linkage, or &lt;/li&gt;&#xA;&lt;li&gt;Torque transmission through a rotating shaft. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In either case, the system should be able to flex both in up-down direction (due to blade flapping) or in forward-aft direction(due to blade lead-lag movement).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One instance where electric motors are actually used for pitch control is in active vibration control, were individual rotor blades are controlled using piezoelectric actuators for vibration control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotor pitch control you are describing would require control forces which are orders of magnitude above that of Individual Blade Control system used and would require a completely new system. Even in this case (where power requirements are modest), &lt;a href=&quot;http://www.southampton.ac.uk/aerospace/research/aerospace/autonomousandadvancedsystems/energy_efficient_avtive_vibration_control_of_helicopters.page&quot; rel=&quot;noreferrer&quot;&gt;University of Southampton&lt;/a&gt; notes,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the dependency of active control on external energy supply can limit its practical applications, particularly in hostile environments, where energy is scarce or unreliable, or where it is impractical to route a power supply.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, using of electric motors would actually have the effect of increasing cost, weight and complexity of an already working system which is not a good idea in an (critical) aircraft system. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-25T10:21:52.647" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21233" PostTypeId="2" ParentId="21212" CreationDate="2015-09-25T11:25:35.893" Score="6" Body="&lt;p&gt;Depending on the size of the aircraft, &lt;em&gt;very&lt;/em&gt; powerful. One way of thinking about his would be that the velocities in the wake are directly related to the lift produced. So, heavier the aircraft, larger the lift and greater the velocities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A human being inside a vortex of a large would feel like he's inside a tornado. For all practical purposes, it is a mini-tornado.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum vortex strength occurs when the aircraft is heavy, slow and clean (with low wingspan). Wind speeds upto 240-&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_90-23G.pdf&quot; rel=&quot;noreferrer&quot;&gt;300&lt;/a&gt; kmph has been recorded in certain cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the main reason for having separation intervals between two aircraft taking off, especially after a 'heavy' aircraft. The best examples of what happens when someone is inside these wingtip vortices comes from incidents where (smaller) aircraft gets caught up in the wake of (larger) aircraft and it doesn't make for very happy reading.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In November 2008, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_340&quot; rel=&quot;noreferrer&quot;&gt;SAAB 340B&lt;/a&gt; got caught in the wake of an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;noreferrer&quot;&gt;Airbus 380&lt;/a&gt; conducting a parallel approach. During this incident, the &lt;a href=&quot;http://www.atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-077.aspx&quot; rel=&quot;noreferrer&quot;&gt;ATSB report&lt;/a&gt; shows that the SAAB 340(which is not a small plane by any mens, having a wingspan of over 20m), &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...experienced an uncommanded 52° roll to the left, in conjunction with an 8° nose-down pitching motion. Immediately after, the aircraft rolled through wings level to a 21° right bank angle. The aircraft also experienced an altitude loss of 300 to 400 ft in the 9 to 15-second period during which the crew regained control of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In the same year, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Learjet_45&quot; rel=&quot;noreferrer&quot;&gt;Learjet-45&lt;/a&gt; flew into the wake turbulence of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_767-300&quot; rel=&quot;noreferrer&quot;&gt;767-300&lt;/a&gt; (separated by 4nm),lost control, &lt;a href=&quot;https://en.wikipedia.org/wiki/2008_Mexico_City_plane_crash&quot; rel=&quot;noreferrer&quot;&gt;killing everyone&lt;/a&gt; on board.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From these incidents, it is pretty clear that getting into the vortices, especially the large one is a very bad idea.  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-25T11:36:32.340" LastActivityDate="2015-09-25T11:36:32.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21235" PostTypeId="2" ParentId="19609" CreationDate="2015-09-25T11:35:20.333" Score="4" Body="&lt;p&gt;Advantages of using electric drivetrain with diesel engines are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;High torque from zero RPM. This is extremely important for trains, because trains have much higher rolling friction in the first few feet before the wheel-driven oil pumps manage to sufficiently lubricate the bearings. Diesel trains that use mechanical drive train even often have additional short-term power sources like steam turbines to help with that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this reason does translate even to cars, which use diesel engines, but with mechanical drive trains. And for helicopters, they don't even need a gear box, because they run the rotor at constant RPM anyway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Batteries can be easily included. This is important for submarines, because they can't run diesel engine below periscope depth, because it needs a lot of oxygen (at periscope depth they can use snorkel). But this is specific to submarines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other vehicles may have use for that as well, for example hybrid cars use it to get higher peak power with smaller engine that can run more efficiently. But helicopters need fairly constant power, so they don't have much use for that either.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So helicopters with diesel engine are possible, and at least Airbus Helicopters are working on it, but the electric part simply has no use. They did not exist so far, because diesel engines were too heavy, but they are becoming light enough that they should be usable in future.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-09-30T04:43:28.227" LastActivityDate="2015-09-30T04:43:28.227" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21236" PostTypeId="2" ParentId="21223" CreationDate="2015-09-25T11:54:08.810" Score="2" Body="&lt;p&gt;It does not matter what type of engine is used; if the Radar is powerful enough and the flying object is near enough (making allowances for any low observable design) i.e. based on the Radar Cross Section, it will be detected by the Radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of small flying objects, the main problem is not in detection (Radars usually &lt;a href=&quot;http://www.weather.com/science/news/radar-birds-bugs-bats-smoke-20130506#/1&quot; rel=&quot;nofollow&quot;&gt;pick up&lt;/a&gt; bugs and such) but in recognizing the object in background clutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the military Radars have an edge as they are more powerful and are optimized for detection of small targets in ground clutter.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-25T11:54:08.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21237" PostTypeId="1" CreationDate="2015-09-25T13:17:57.733" Score="1" ViewCount="896" Body="&lt;p&gt;I am making a report and how does EGT of an aircraft, either turbo or piston engine, work? Can you please give me the procedures... Like where it starts and being transferred to where and stuff. Thank you!&lt;/p&gt;&#xA;" OwnerUserId="11252" LastEditorUserId="1696" LastEditDate="2015-10-01T17:53:38.403" LastActivityDate="2015-10-01T17:53:38.403" Title="How does EGT work?" Tags="&lt;engine&gt;&lt;temperature&gt;&lt;egt&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-09-29T18:17:59.863" ContentLicense="CC BY-SA 3.0" />
  <row Id="21238" PostTypeId="2" ParentId="21223" CreationDate="2015-09-25T13:28:53.683" Score="3" Body="&lt;p&gt;Radar detection depends on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Scattering&quot; rel=&quot;nofollow noreferrer&quot;&gt;scattering&lt;/a&gt; of radar waves on objects. If we use the common &lt;a href=&quot;https://en.wikipedia.org/wiki/X_band&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-band&lt;/a&gt; (8-12 GHz frequency) as an example, the wavelength $\lambda$ of the radar waves is in the order of 3&amp;nbsp;cm. Now the size of the target comes into play, expressed as a ratio α, defined as $$\alpha = \frac{\pi\cdot D}{\lambda}$$&#xA;with $D$ the diameter of the object to be detected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;α ≪ 1: Rayleigh scattering (small particle compared to wavelength of light)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;α ≈ 1: Mie scattering (particle about the same size as wavelength of light, valid only for spheres)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;α ≫ 1: geometric scattering (particle much larger than wavelength of light).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only for large α you will get a return signal which can be used for detection. Then we speak no longer of scattering, but of &lt;a href=&quot;https://en.wikipedia.org/wiki/Geometrical_optics&quot; rel=&quot;nofollow noreferrer&quot;&gt;reflection&lt;/a&gt;. If your MEMS engine is just a few mm across and attached to a plastic airframe (which should be transparent to radar waves), it should be impossible to detect with conventional radars. Since the atmosphere is rather opaque for microwave radiation above 20 GHz, infrared or optical detectors will be needed to detect such an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the software driving the radar display is an important factor. Common aviation radars will &lt;a href=&quot;https://aviation.stackexchange.com/questions/16722/would-a-homemade-lawn-chair-balloon-be-visible-on-atc-and-collision-avoidance-ra&quot;&gt;filter out small, slow-moving objects&lt;/a&gt;, so even a metallic or carbon-composite airframe several centimeters across will not be detected.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-25T13:49:12.780" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21240" PostTypeId="1" AcceptedAnswerId="21241" CreationDate="2015-09-25T14:59:18.180" Score="39" ViewCount="33685" Body="&lt;p&gt;As a kid I distinctly remember seeing aircraft like the bright blue KLM MD-11 having the prominent third engine on the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EITgo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EITgo.jpg&quot; alt=&quot;https://en.wikipedia.org/wiki/KLM#/media/File:KLM_MD_11_AMS.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:KLM_MD_11_AMS.jpg&quot; rel=&quot;noreferrer&quot;&gt;https://commons.wikimedia.org/wiki/File:KLM_MD_11_AMS.jpg&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I don't think I've seen a plane in the past few years (besides maybe a few smaller private jets) that has a engine on the tail - let alone a trijet configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's with their disappearance?&lt;/p&gt;&#xA;" OwnerUserId="1824" LastEditorUserId="14897" LastEditDate="2018-01-11T17:44:25.640" LastActivityDate="2020-11-05T19:38:29.400" Title="Why don't passenger aircraft use the trijet configuration anymore?" Tags="&lt;aviation-history&gt;&lt;engine-placement&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21241" PostTypeId="2" ParentId="21240" CreationDate="2015-09-25T15:22:31.787" Score="44" Body="&lt;p&gt;The fewer engines an aircraft has, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9760/why-does-the-bae-146-have-higher-maintenance-costs-than-other-comparable-jet-air&quot;&gt;the lower are its operating cost&lt;/a&gt;. Engines are the most maintenance-intensive part of an aircraft, and doing a hot section inspection on two large engines &lt;a href=&quot;https://www.conklindd.com/t-guaranteedenginemaintenanceprograms.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;costs less&lt;/a&gt; than doing it on three somewhat smaller engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the &lt;a href=&quot;https://en.wikipedia.org/wiki/Trijet&quot; rel=&quot;nofollow noreferrer&quot;&gt;tri-jets&lt;/a&gt; were developed, no sufficiently large and powerful engines were available. They were already cheaper to operate than the four-engined aircraft, and too large to have sufficient power with just two. Now, with engines which can deliver a static thrust of &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow noreferrer&quot;&gt;more than 100,000 pounds&lt;/a&gt;, everything below a Jumbo Jet or an A380 can be powered with just two engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is increased engine reliability: With three or four engines, an engine failure is less of a problem than with just two engines per airplane. Previously, route planning had to keep a maximum distance of 60 flight minutes to a diversion airport. In 1964, this was waived for three-engined aircraft, but twins were still bound to this restriction. With more experience and better engines, this rule &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;has been relaxed for twins&lt;/a&gt; gradually to 120 (1985), then 180 (1988), and now 370 (2014) minutes for the Airbus A350 XWB, and twins have become much more versatile for their airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the old tri-jet designs were quite popular with operators: The last &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-154&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev Tu-154&lt;/a&gt; was built only in 2013. But besides the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Falcon_900&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassault Falcon 900&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Falcon_7X&quot; rel=&quot;nofollow noreferrer&quot;&gt;7X&lt;/a&gt; business jets, I don't know of any trijet which is still in production.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-04-28T04:44:10.573" LastActivityDate="2019-04-28T04:44:10.573" CommentCount="20" ContentLicense="CC BY-SA 4.0" />
  <row Id="21242" PostTypeId="2" ParentId="21240" CreationDate="2015-09-25T16:24:49.500" Score="23" Body="&lt;p&gt;The main reason for selecting three engines was reliability issues with gas turbine engines used in the dawn of the jet age. The FAA Operating Requirements §121.161 &lt;em&gt;Airplane limitations: Type of route&lt;/em&gt; says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... no certificate holder may operate a turbine-engine-powered airplane over a route that contains a point—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Farther than a flying time from an Adequate Airport (at a one-engine-inoperative cruise speed under standard conditions in still air) of 60 minutes for a two-engine airplane or 180 minutes for a passenger-carrying airplane with more than two engines&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most of the initial tri-jets were configured for long range operations as twin engined aircraft could not be operated in most transatlantic routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as the engine reliability has improved, the regulatory authorities have certified a number of twin engined aircraft for ETOPS (Extended Range Twin Engined Operations). As airlines prefer as few engines as possible (which translates into lower upfront and operating costs), tri-jets have become a relic of the past. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintaining the third engine on top of the fuselage is a major headache compared to the other two. Also, the placing the third engine has been a design trade-off between aerodynamic efficiency on the one hand and easier installation (and lesser cost) on the other hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same reasons, we are not seeing any four engined aircraft and every aircraft under development is twin-engined. Also, improvements in engine power (777's GE-90 produces nearly twice the thrust of MD-11's GE CF-6) and fuel economy (today's aircraft burn around 10% less fuel compared to the aircraft from 1980s) mean that the necessary thrust (and range) can be generated by lesser number of engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another (minor) point is that the bypass ratios have increased in the recent decades and this might present difficulties in placement of the center engine.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-25T16:35:21.000" LastActivityDate="2015-09-25T16:35:21.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21244" PostTypeId="1" AcceptedAnswerId="21247" CreationDate="2015-09-25T18:34:01.330" Score="14" ViewCount="9084" Body="&lt;p&gt;According to the FAA's &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_00-45G_CHG_1-2.pdf&quot; rel=&quot;noreferrer&quot;&gt;AC 00-45G&lt;/a&gt; section 3.1, a METAR is defined:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aviation Routine Weather Report (METAR) is the primary observation code used in the U. S. to&#xA;  satisfy World Meteorological Organization (WMO) and International Civil Aviation Organization&#xA;  (ICAO) requirements for reporting surface meteorological data. A METAR report includes the&#xA;  airport identifier, time of observation, wind, visibility, runway visual range, present weather&#xA;  phenomena, sky conditions, temperature, dew point, and altimeter setting. Excluding the airport&#xA;  identifier and the time of observation, this information is collectively referred to as “the body of the&#xA;  report.” As an addition, coded and/or plain language information elaborating on data in “the body&#xA;  of the report” may be appended to the end of the METAR in a section coded as&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;“Remarks.” The contents of the “Remarks” section vary with the type of reporting station. The&#xA;  METAR may be abridged at some designated stations only including a few of the mentioned&#xA;  elements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What doesn't appear to be defined is exactly what area the METAR covers. It's understood that a METAR is a reporting for a particular station's current conditions at a particular time, but is there a more discrete definition for where the METAR's conditions can be expected?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The definition of a TAF specifically states that the forecast conditions are expected in an area around the reporting station with a radius of 5 statute miles. The METAR has no such specification that I can find.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="14957" LastEditDate="2020-03-02T14:04:27.700" LastActivityDate="2020-03-02T14:05:52.593" Title="What geographical area does a METAR cover?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21245" PostTypeId="1" AcceptedAnswerId="21253" CreationDate="2015-09-25T18:36:23.987" Score="17" ViewCount="2888" Body="&lt;p&gt;In this photo of N46L, a Beech A200 Super King Air owned by Dynamic Aviation, there is a large pod attached to the belly with what looks like two largish ports or windows on the underside.  What is it, exactly?  It looks similar to a synthetic aperture radar pod or video surveillance package, but I was curious if anyone could ID it precisely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HFYW3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HFYW3.jpg&quot; alt=&quot;Pod on underside of King Air&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full photo is available at &lt;a href=&quot;http://www.jetphotos.net/viewphoto_new.php?id=7118680&quot; rel=&quot;noreferrer&quot;&gt;http://www.jetphotos.net/viewphoto_new.php?id=7118680&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3037" LastEditorUserId="3037" LastEditDate="2015-09-26T20:55:21.330" LastActivityDate="2018-04-08T20:06:40.903" Title="What is the belly pod on this Beech A200 Super King Air?" Tags="&lt;military&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21246" PostTypeId="1" AcceptedAnswerId="21266" CreationDate="2015-09-25T18:55:10.843" Score="7" ViewCount="530" Body="&lt;p&gt;What parameters and types of performance are designers trying to maximize when building an air dominance fighter plane rather than a ground support fighter? What are the trade offs between them - what do I sacrifice to make a great fighter aircraft vs. a great ground support aircraft?&lt;/p&gt;&#xA;" OwnerUserId="9576" LastEditorUserId="1467" LastEditDate="2018-02-15T14:14:21.893" LastActivityDate="2018-02-15T14:14:21.893" Title="What are the differences in design considerations for ground attack and air dominance aircraft?" Tags="&lt;fighter&gt;&lt;fixed-wing&gt;&lt;bomber&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21247" PostTypeId="2" ParentId="21244" CreationDate="2015-09-25T19:19:17.727" Score="14" Body="&lt;p&gt;Geographically METARS are for a single specific location (the station identified in the report).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An automated METAR with no human supervision covers the conditions within approximately 6 inches of the weather station reporting it (for example, a badly positioned AWOS/ASOS station may be shielded from wind in some directions which affects what it reports).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A manual (or manually augmented) METAR covers the conditions the weather observer can physically see (clouds, precipitation, visibility, etc.) in addition to the ones they can measure (temperature, dew point, barometric pressure), which are valid for the point of measurement. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Practically speaking&lt;/em&gt; if the weather station is positioned well a METAR (like a TAF) is probably fairly representative of conditions within 5 miles, assuming there are no geographic features such as mountains which may mess with the weather. The data is still still &quot;useful&quot; within about 20 miles (e.g. &lt;code&gt;KMTP&lt;/code&gt; uses the weather reported by &lt;code&gt;KHTO&lt;/code&gt;, about 17 miles away), though you should obviously cross-check it - in that example the winds at Montauk (right on the water) can be noticeably different from the winds at East Hampton (further inland).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some information is broadly useful over a wider area. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1121&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 91.121&lt;/a&gt; requires you to set your altimeter to the value reported by a station &quot;within 100 nautical miles&quot; of your position when you're operating below 18,000 feet because things like barometric pressure tend to affect relatively large areas.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="14957" LastEditDate="2020-03-02T14:05:52.593" LastActivityDate="2020-03-02T14:05:52.593" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21248" PostTypeId="2" ParentId="19609" CreationDate="2015-09-25T20:28:08.097" Score="6" Body="&lt;p&gt;One thing I don't see addressed yet in other answers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for diesel-electric systems is that diesel engines (in fact, all ICE engines) are only efficient at certain RPM values. For road vehicles that accelerate and decelerate a lot, this means that most of the time, your directly linked engine is not working efficiently. To alleviate this problem, you can either have a fancy gearbox (for example, dual-clutch or CVT - or even a normal gearbox will do), or have an generator and an electric motor: this is a very handy 'gearbox' since electrons are so easy to manipulate. Some (prototype) hybrid cars also use this system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters almost invariably operate at a &lt;strong&gt;fixed RPM&lt;/strong&gt; set by the governor. This means that whatever engine is employed, you can just let it run at the best RPM using a simple fixed geared transmission. Actual variations in lift are done with blade pitch, not motor RPM. The whole point of having an electric system, (which is just a very fancy transmission like some sort of CVT), is then negated, which is why this system will never be used in both propeller fixed-wings and helicopters alike.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2015-09-25T20:28:08.097" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21249" PostTypeId="2" ParentId="21240" CreationDate="2015-09-25T21:28:45.863" Score="13" Body="&lt;p&gt;Other (great) answers have already covered most reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Business Jets side, you can do this : &lt;a href=&quot;http://www.airteamimages.com/dassault-falcon-7x_CS-DTS_masterjet_176224.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.airteamimages.com/dassault-falcon-7x_CS-DTS_masterjet_176224.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But not that often with airliners. :P&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, joking put aside...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cost&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A third (or second) engine on/below the tail adds specific parts/components, that have to be manufactured, maintained, and spare parts have to be made available for the entire lifetime of the type. Just like the reason why &quot;eyebrows&quot; were removed from the 737 line, and not a single airliner has purchased the 777 with folding wings (and the idea dropped on A380-like projects), reducing costs is a relevant reason to not manufacture &quot;special&quot; parts whenever possible. Best sellers are aircraft that are &lt;em&gt;cheap&lt;/em&gt; to handle and maintain. If you can use larger engines to get two instead of three, then...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar reasons for unmounting the #2 engine. On a relatively small jet, you can unmount the engine just like it was on the Boeing 727. However, to make that possible with engines the class (and size) of a GE90, you need strengthened structures (increased weight: bad!) around the tail cone, special lifters, a tail cone large enough to contain that engine, compliant with regulation in case of a fan blade failure. Hydraulics and other electrical wiring must be secured. That adds many more special components that have to be checked for airworthiness on a regular basis. When your aircraft is stuck at an airport without the appropriate equipment, you must ferry them there, with the replacement engine. Cost!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's highly unlikely we'll see a tail mounted engine on airliners the size of a 777 in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Noises and vibrations&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small engines are OK. Large engines not that much. Even with the incredible progress we have made in reducing engine noise, vibrations are still a major factor, and engine pylons are the best way we have to reduce them. A tail mounted engine doesn't really have a pylon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aerodynamics&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Brutally pitching up the aircraft can reduce or disturb the #2 engine intake airflow, with sometimes noticeable issues. This is a major concern for pilots operating on hot and high conditions. This also happens during stall and deep stall. Tail mounted engines requires larger or extra tail surfaces to stabilize the aircraft and reduce drag (weight + more parts to maintain)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aircraft behaviour&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the engines are not mounted in line with the other two (DC10/MD11, Tristar), the center engine produces some specific pitching behaviours depending on loading, thrust and flight phases. It's worse in the case of one inoperative engine. While this behaviour has saved the life of many in the past, it was also a factor in some crashes or close calls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: aircraft behaviour varies greatly between a short version of the frame to a longer one. Stretching a three engined aircraft requires much more research, development and testing than a twin engine one. Having optimized types meeting airlines requirements in your catalog is not that easy with three engined aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Safety concerns&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a component failing at a high rotation speed, a fuel leak, or a fire, mounting the engine in the fuselage is obviously not the most seducing option. The not so distant Qantas A380, Air Transat A330, Concorde in Gonnesse... Fighting a fire on the engine #2 of a Tristar is not the same as fighting the fire on the BA 777 at Las Vegas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can't conduct a fan blade overview upon walk around on engine #2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Reengining&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can create new nacelles for more powerful, quieter and more fuel saving engines for a 737 (100/200 &gt; Classics &gt; NG &gt; Max &gt; ...) or an A32x (Neo), avoiding the need to develop an entirely new air frame. Reengining the 727 had mitigated results. All KC135 have been reengined and the 747 with the 8I/F. A330 and 777s... Going from the DC10 to the final version of the MD11 (which is basically a reengined and stretched DC10) wasn't that easy. Many retrofits were made available several years after the MD11 entered commercial service. As we don't clearly know what the future is made of, a three engined aircraft may fail to comply with future technologies, which disallows lengthening the lifetime of the type, unless designed from the start to be upgraded, like the Falcon 7X (larger/heavier versions in the plans).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;However, having three engines is not a bad thing. It all depends on the purpose of the aircraft. One extra engine can reduce take off roll, allow the selection of smaller and quieter engines (in some rare cases), increase ETOPS certification, give access to hot and high airports, etc. If those reasons are relevant enough to cancel the extra cost required by the extra engine, then you can manufacture a three engined aircraft (or a six engined, like the An225).&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="5517" LastEditDate="2015-09-28T19:18:07.877" LastActivityDate="2015-09-28T19:18:07.877" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21250" PostTypeId="1" AcceptedAnswerId="21251" CreationDate="2015-09-25T21:57:57.927" Score="19" ViewCount="22838" Body="&lt;p&gt;The abbreviation for a condition of mist is &lt;code&gt;BR&lt;/code&gt; on METAR and TAF reports. How did mist end up getting abbreviated as BR?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2015-09-25T22:13:35.407" LastActivityDate="2015-09-26T09:44:13.863" Title="Why is mist abbreviated BR on METARs and TAFs?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21251" PostTypeId="2" ParentId="21250" CreationDate="2015-09-25T22:07:40.653" Score="22" Body="&lt;p&gt;&lt;a href=&quot;http://www.cfidarren.com/r-metarmystery.htm&quot;&gt;According to a CFI's lesson plan on the internet&lt;/a&gt;, it comes from the French word for mist, &lt;strong&gt;&lt;a href=&quot;https://en.wiktionary.org/wiki/brume&quot;&gt;&lt;em&gt;brume&lt;/em&gt;&lt;/a&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-09-25T22:07:40.653" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21252" PostTypeId="2" ParentId="21222" CreationDate="2015-09-25T22:36:54.387" Score="12" Body="&lt;p&gt;I went on a little search on my university library database, and found a review paper. I'm not sure if you can access it without paying.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Active rotor control for helicopters: individual blade control and swashplateless rotor designs&lt;/strong&gt; by Ch. Kessler. Link: &lt;a href=&quot;http://dx.doi.org/10.1007/s13272-011-0001-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://dx.doi.org/10.1007/s13272-011-0001-0&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;There, I extracted three sources relevant to your question:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Kretz, M.: Research in multicyclic and active control of rotary&#xA;wings. Vertica 1(2), 95–105 (1976)&lt;/li&gt;&#xA;&lt;li&gt;Guinn, K.F.: Individual blade control independent of a swashplate.&#xA;J. AHS 27(3), 25–31 (1982)&lt;/li&gt;&#xA;&lt;li&gt;Arnold, U.T.P., Fuerst, D., Neuheuser, T., Bartels, R.: Development&#xA;of an integrated electrical swashplateless primary and&#xA;individual blade control system. In: 32nd ERF, Maastricht, The&#xA;Netherlands, September 12–14, 2006&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;If you're lucky, you can find a way to access these papers - however, my university didn't seem to have subscriptions to the relevant journals (either way, they weren't in the database).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;In all these papers, the main motivation was to reduce vibrations caused by aeroelastic effects.&lt;/strong&gt; This means that the interaction between blade elasticity and airflow causes unwanted vibrations which cannot be solved by a swashplate, since a swashplate can only actuate frequencies at the number of blades times the RPM. &lt;strong&gt;Friction from the swashplate configuration is of minor importance&lt;/strong&gt;. A swashplate is generally just a set of ball bearings, which have the nice property that the forces on them are always at a right angle, i.e. a centripetal force which does not cause energy losses. The only energy loss is due to rolling friction, which is extremely small (I found friction coefficients of 0.005 in a paper on lubrications) for properly designed bearings. All in all, very minor compared to the massive power needed to lift a helicopter up.&lt;/p&gt;&#xA;&lt;p&gt;Note that electronic actuators are not particularly efficient in all situations. &lt;strong&gt;(following part revised to clear up some confusion:)&lt;/strong&gt; Imagine lifting a heavy box off a high shelf. Even though strictly speaking, you're doing negative work on the box, you still feel tired afterwards because for human muscles and (simple) electric actuators alike, it costs energy to apply a force. In other words, an electric motor also has to provide the negative work on a system, unless there are energy recovery systems integrated. This was actually proposed in one paper to overcome overheating issues. Furthermore, for a constant force (no work), a constant current flow is still needed in an electronic actuator.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Perhaps I best quote Kessler in his conclusion (shortened):&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Individual blade control can alleviate a lot of typical&#xA;helicopter problems:&lt;/p&gt;&#xA;&lt;p&gt;• reduce the cabin vibration by 80% or even more,&lt;/p&gt;&#xA;&lt;p&gt;• reduce component loads and power required, [...]&lt;/p&gt;&#xA;&lt;p&gt;That is the good news. And now the bad:&#xA;About 58 years of research and development on HHC and&#xA;IBC have passed by. And no helicopter is equipped with&#xA;such a system. [...] But even for customers it might be difficult to see an advantage of IBC and a payback. [...] An IBC system would surely&#xA;raise the purchase price.[...] On the other side,&#xA;designs get more and more complex, the swashplateless&#xA;concepts are the far end of this complexity. It should be&#xA;questioned if this is still reasonable. The advice would be,&#xA;‘‘make one step after the other; do not try to do two at the&#xA;same time.’’&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2021-05-10T14:08:04.637" LastActivityDate="2021-05-10T14:08:04.637" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="21253" PostTypeId="2" ParentId="21245" CreationDate="2015-09-25T23:15:32.913" Score="21" Body="&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&lt;p&gt;It seems to be a US Army CEASAR pod, a communication intercepting and jamming system for electronic warfare, which has been flown in Iraq and Afghanistan. CEASAR is derived from AN/ALQ-227 EA used by US Navy on the &lt;a href=&quot;http://www.naval-technology.com/projects/ea-18g-growler/&quot; rel=&quot;noreferrer&quot;&gt;EA-18G Growler&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The aircraft is equipped with missile detection and countermeasures. Two sensors are below the cockpit windscreen, two other on the aft fuselage. The chaff is released by a dispenser aft of the pod.&lt;/p&gt;&#xA;&lt;p&gt;N40R is N46L's sister aircraft, and it also carries a CEASAR pod. The A200 variant used may be a C12-A or a C-12C (this is the model number visible on N40R fuselage). They are also known as &lt;em&gt;Huron&lt;/em&gt; and &lt;em&gt;HC-12&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;p&gt;High definition photo of N46R:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/txgAU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/txgAU.jpg&quot; alt=&quot;High definition photo of N46R&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Photo by &lt;a href=&quot;http://s261.photobucket.com/user/keithnewsome/profile/&quot; rel=&quot;noreferrer&quot;&gt;Keith Newsome&lt;/a&gt; on photobucket (&lt;a href=&quot;http://s261.photobucket.com/user/keithnewsome/media/DSC_3106.jpg.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Detailed answer below.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;About CEASAR&lt;/h2&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.stripes.com/news/new-technology-can-jam-intercept-insurgent-transmissions-1.174720#&quot; rel=&quot;noreferrer&quot;&gt;Stars and Stripes&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The CEASAR, which stands for communications electronic attack with&#xA;surveillance and reconnaissance, is a rectangular metal box that holds&#xA;technology capable of both knocking out cell phones and radios and&#xA;intercepting transmissions, while an electronic warfare officer&#xA;onboard speaks directly to troops on the ground. It’s precise enough&#xA;to cover friendly soldiers while jamming insurgents, but not knocking&#xA;out communications for an entire village near a given operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z3DBy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z3DBy.jpg&quot; alt=&quot;Air crew disembarking the aircraft&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.matthewaid.com/post/84445892216/contractors-continue-flying-ceasar-sigint-aircraft&quot; rel=&quot;noreferrer&quot;&gt;matthewaid.com&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Contractors Continue Flying CEASAR SIGINT Aircraft in Afghanistan&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;The CEASAR system mounted in these contractor-owned and&#xA;government-operated (COGO) aircraft is based on the Raytheon&#xA;AN/ALQ-227 EA system as fitted to the US Navy’s (USN’s) Boeing EA-18G&#xA;Growler electronic warfare (EW) aircraft. It is designed to provide&#xA;both a communications jamming and an intercept/monitoring capability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hNwJc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hNwJc.jpg&quot; alt=&quot;Manoeuvring aircraft&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h2&gt;CEASAR UAV replacement&lt;/h2&gt;&#xA;&lt;p&gt;Flying CEASAR on a modified A200 was already very much cheaper than using a pod on a fighter. However like for other functions, military are looking at using unmanned aircraft. The NERO pod has been designed for this purpose.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://defensesystems.com/articles/2014/07/17/army-nero-electronic-warfare-drones.aspx&quot; rel=&quot;noreferrer&quot;&gt;Defense Systems&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;NERO jams aboard a drone in Army test&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;The Army recently tested a jammer called the Networked Electronic&#xA;Warfare Remotely Operated, or NERO, attached to a Gray Eagle unmanned&#xA;combat aircraft at the Great Salt Lake Desert at Dugway Proving&#xA;Ground, Utah.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uLc57.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uLc57.png&quot; alt=&quot;NERO drone on the ground&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Missile Warning System AN/AAR-47&lt;/h2&gt;&#xA;&lt;p&gt;Closer view (N40R):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0q7Qa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0q7Qa.jpg&quot; alt=&quot;Aircraft cockpit exterior, showing the sensor stalks&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;It detects infrared or radio sensing from a missile and commands a response, e.g. release of chaff or flare using the countermeasures dispensing system aft of the pod.&lt;/p&gt;&#xA;&lt;p&gt;Two other sensors are located &lt;a href=&quot;http://www.jetphotos.net/viewphoto_new.php?id=7118680&quot; rel=&quot;noreferrer&quot;&gt;on the aft fuselage&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Sensor detail on another aircraft:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gIjWt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gIjWt.jpg&quot; alt=&quot;Close-up of sensor&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(&lt;a href=&quot;http://vpk.name/news/127491_ssha_postavyat_indii_stancii_preduprezhdeniya_o_raketnom_napadenii.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;About the aircraft&lt;/h2&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=FSB%20BE-200&quot; rel=&quot;noreferrer&quot;&gt;FAA&lt;/a&gt;, King Air A200, CN &lt;code&gt;BC-1&lt;/code&gt; thru &lt;code&gt;BC-61&lt;/code&gt; are variant C-12A used by US Army.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://jetphotos.net/showphotos.php?regsearch=N46L&quot; rel=&quot;noreferrer&quot;&gt;JetPhotos.net&lt;/a&gt; this aircraft is used under call-sign Grizzly 23:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Registration: N46L&lt;br /&gt;&#xA;CN: BC-56&lt;br /&gt;&#xA;'Grizzly 23' taxies for departure to Wick.this is one of a number of&#xA;aircraft owned by Dynamic that operate on behalf of the US Army.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There are two C-12 aircraft equipped with CEASAR. The other is registered N40R, with call-sign &lt;em&gt;Grizzly 12&lt;/em&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xnzdn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xnzdn.jpg&quot; alt=&quot;N46L and N40R on the ground&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(&lt;a href=&quot;http://www.fightercontrol.co.uk/forum/viewtopic.php?f=16&amp;amp;p=472631&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;Huron are &lt;a href=&quot;http://www.militaryaerospace.com/articles/2013/11/army-dash8-comint.html&quot; rel=&quot;noreferrer&quot;&gt;seconded or being replaced by Dash 8&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-17T14:53:59.153" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21254" PostTypeId="1" AcceptedAnswerId="21261" CreationDate="2015-09-26T00:04:12.007" Score="8" ViewCount="929" Body="&lt;p&gt;I was watching the news and, just now, learned that the Russians used a &quot;trick&quot; by flying a fighter plane under a cargo plane to Syria and successfully avoided radar detection for the fighter plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wanted to learn more about this method (a Wiki article, for instance) but failed to find anything. So do the experts here know what this term is called, if there even is one?&lt;/p&gt;&#xA;" OwnerUserId="11391" LastEditorUserId="1467" LastEditDate="2018-01-25T09:29:15.117" LastActivityDate="2018-01-25T09:29:15.117" Title="What is the official term of a plane flying under another plane to avoid radar?" Tags="&lt;radar&gt;&lt;flying-in-formation&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21255" PostTypeId="2" ParentId="21244" CreationDate="2015-09-26T00:56:49.323" Score="7" Body="&lt;p&gt;A metar report is good within 5 NM of the station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;VC&quot; or vicinity of the airport is defined as between 5-10NM from the station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;DSNT&quot; or Distant is used beyond 10NM from the station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ofcm.gov/fmh-1/pdf/FMH1.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://www.ofcm.gov/fmh-1/pdf/FMH1.pdf&lt;/a&gt; page 42.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-09-26T00:56:49.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21256" PostTypeId="1" AcceptedAnswerId="21263" CreationDate="2015-09-26T01:03:22.293" Score="6" ViewCount="1584" Body="&lt;p&gt;I happened to be walking past a small outdoor fair today, and saw someone flying a paramotor. The craft took off and started a steep ascending turn losing speed rapidly, seemed almost to come to a stop (relative the ground, but the flags nearby didn't show much wind, either) before the pilot brought it back to more level flight and got some way again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not a pilot, but I'm roughly aware of the mechanism of stalls and the consequent danger of high angle of attack, low speed maneuvers and I was briefly worried that there was going to be a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In hindsight, the craft clearly has a very low stall speed (not much more than walking speed, I guess) but it did leave me wondering. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these craft are more or less at risk of stalling than conventional fixed wing aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1039" LastEditorUserId="167" LastEditDate="2015-09-26T02:32:45.083" LastActivityDate="2015-09-27T21:09:12.730" Title="How does stall risk in paramotors differ from that of conventional fixed-wing aircraft?" Tags="&lt;stall&gt;&lt;fixed-wing&gt;&lt;ultralight&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21257" PostTypeId="1" AcceptedAnswerId="21259" CreationDate="2015-09-26T03:54:40.653" Score="9" ViewCount="1759" Body="&lt;p&gt;I've seen these (note the parts pointed to by the red arrows in the image) on the landing gear struts of Super Cubs and plenty of other STOL bush planes with large tundra tires. It looks like maybe just an aerodynamic fairing on the gas tube/strut of the landing gear but I'm wondering why on every example I've seen of this, the aerodynamic shapes are angled differently (one is more &quot;up&quot; than the other). What is this if I'm wrong about what it is and most of all why are they always angled differently? Is this to try and help with adverse yaw or something?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see them in this video here (note that they, too, like all I've seen, are angled differently): &lt;a href=&quot;https://youtu.be/KEF7s5tKXpA?t=5m30s&quot; rel=&quot;noreferrer&quot;&gt;FlightChops Super Cub&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IQuqk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IQuqk.jpg&quot; alt=&quot;Sweet Super Cub&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="14897" LastEditDate="2018-06-04T17:53:47.893" LastActivityDate="2018-06-04T17:53:47.893" Title="What are these parts on STOL/bush planes?" Tags="&lt;landing-gear&gt;&lt;feature-identification&gt;&lt;bush-flying&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21258" PostTypeId="2" ParentId="8665" CreationDate="2015-09-26T04:19:09.453" Score="38" Body="&lt;p&gt;Three reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The B-52 stayed useful by taking on &quot;easier&quot; roles as it aged.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It actually started life as a high-performance penetrator, relying on speed and altitude to stay safe. Think Early Cold War, shortly after WWII.&lt;/li&gt;&#xA;&lt;li&gt;When ground-launched missiles improved, the B-52 was forced into flying low-altitude penetration underneath radars (a role for which it was NOT designed and rapidly wore out the airframe) accompanied by a host of other aircraft to protect it and help it penetrate defenses. Despite their escorts, we lost low-dozens of B-52s in Vietnam.&lt;/li&gt;&#xA;&lt;li&gt;Later in the Cold War, the B-52 was completely outmatched by air defenses (fighters, SAMs, etc), and had little hope of penetrating defenses (at either low or high altitude) to drop nuclear bombs. Instead, it was relegated to flying in friendly/neutral airspace, lobbing &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-129_ACM&quot; rel=&quot;noreferrer&quot;&gt;long-range&lt;/a&gt; nuclear &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-86_ALCM&quot; rel=&quot;noreferrer&quot;&gt;cruise missiles&lt;/a&gt; into the Soviet heartland (a tactic they feared more, as it turned out, than manned low-level penetrators). It was basically a missile bus.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.reddit.com/r/CredibleDefense/comments/3cbgs5/the_gulf_war_air_power_survey_1993_with_figures/&quot; rel=&quot;noreferrer&quot;&gt;In the Gulf War&lt;/a&gt;, the B-52 only flew after air defenses had &lt;em&gt;already&lt;/em&gt; been defeated by other aircraft (F-16s, F-15s, F-111s, etc). It was basically a bomb truck.&lt;/li&gt;&#xA;&lt;li&gt;During ALLIED FORCE (1999), &lt;a href=&quot;https://www.reddit.com/r/CredibleDefense/comments/3jhcm4/the_2018_bomber_the_case_for_accelerating_the/cup6dir?context=3&quot; rel=&quot;noreferrer&quot;&gt;&quot;B-1Bs and other conventional (non-stealthy) aircraft could not survive in the face of double digit SAMs, even when employing advanced decoys and other countermeasures.&quot;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;The B-1 program, btw, went through a similar progession, starting out as a high-performance penetrator,  then forced into even lower-altitude penetration, then also relegated to bomb/missile trucking, pushed back by AAA, MANPADS, SAMs, look-down shoot-down radar, improved Soviet interceptors, and Soviet AWACS. In fact, the B-1 and B-52 fly largely* the same missions today. &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;*There are some important differences. The &lt;a href=&quot;https://www.military.com/daily-news/2017/07/12/start-lanced-the-b-1s-nukes-but-bomber-will-still-get-new-bombs.html&quot; rel=&quot;noreferrer&quot;&gt;B-1 is no longer nuclear capable&lt;/a&gt; (START compliance), leaving that mission to the 20 B-2s and &lt;a href=&quot;http://www.airforce-technology.com/uncategorised/newsusaf-converts-b-52h-bomber-fleet-to-conventional-only-capability-4674701/&quot; rel=&quot;noreferrer&quot;&gt;~40&lt;/a&gt;+ &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-86_ALCM&quot; rel=&quot;noreferrer&quot;&gt;ALCM&lt;/a&gt;-armed B-52s. The B-1 can also reposition more quickly, &lt;a href=&quot;http://aviationweek.com/site-files/aviationweek.com/files/uploads/2015/03/CloseAirSupport_chart2B.jpg&quot; rel=&quot;noreferrer&quot;&gt;lending it to CAS role&lt;/a&gt;: it dropped &lt;a href=&quot;https://www.armytimes.com/resizer/vqYVIyli4eSdJGxCqlpWTzVKncE=/600x0/filters:quality(100)/arc-anglerfish-arc2-prod-mco.s3.amazonaws.com/public/A3XREGD4AFDDJFGA52IL3PPBII.jpg&quot; rel=&quot;noreferrer&quot;&gt;37% of the then-total ordnance&lt;/a&gt; on ISIS (&lt;a href=&quot;https://i1.wp.com/fightersweep.com/wp-content/uploads/2016/03/635944267989121579-AIR-WEB-Air-Force-Missions-against-ISIS-04-04-16.jpg?w=540&amp;amp;ssl=1&quot; rel=&quot;noreferrer&quot;&gt;2x that of the A-10&lt;/a&gt;)(see &lt;a href=&quot;https://fightersweep.com/4850/oir-f-16s-fly-most-b-1s-drop-most/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) in OIR before they returning stateside for upgrades and were relieved by B-52s. (And, yes, &lt;a href=&quot;https://breakingdefense.com/2014/05/sen-mccain-b-1s-really-do-cas/&quot; rel=&quot;noreferrer&quot;&gt;the B-1 does CAS&lt;/a&gt;.)&lt;/li&gt;&#xA;&lt;li&gt;Overall, the B-1s fly ~330-450 hours/yr, the B-2 ~230-290 hours/yr, and the B-52s ~200-220 hours/yr (2008-2012). The B-1 and B-52 cost roughly the same per hour (the B-1 has higher fixed costs but lower operational CPFH). &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In 40 years, the B-52 went from being the US' primary strategic tool against another superpower to being outclassed by small nations. &lt;/li&gt;&#xA;&lt;li&gt;Bomb/missile trucking is an &quot;easy&quot; job, but &lt;a href=&quot;https://www.reddit.com/r/CredibleDefense/comments/3g4kgk/why_doesnt_long_range_strike_split_off_into_a/ctuxa02?context=3&quot; rel=&quot;noreferrer&quot;&gt;far from ideal&lt;/a&gt;. You can't bomb your targets until the air defenses have &lt;em&gt;already&lt;/em&gt; been defeated---after the &quot;first week&quot; of a war, the most critical phase, when you need them the most. In other words, the B-52 (and B-1) are relatively easy to shoot down, so they're not nearly as useful as they used to be. You can't fly them unless many of the toughest enemies are already dead. So you can't use them as often as you want.&lt;/li&gt;&#xA;&lt;li&gt;@MSalters phrased it quite nicely: the reason the B-52 (and B-1) hasn't changed is because other aircraft are doing the hard work for them (tearing down enemy defenses), and such aircraft have advanced &lt;em&gt;immensely&lt;/em&gt;. But that amount of support is quite resource intensive, so if you wanted to fly B-52s in the &quot;first week&quot; when enemy defenses are still effective, you'll need a lot of help:&lt;br&gt;&lt;a href=&quot;https://i.stack.imgur.com/QGbs8.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGbs8.png&quot; alt=&quot;value of stealth&quot;&gt;&lt;/a&gt;&lt;br&gt; &lt;sup&gt;(Image source: &lt;a href=&quot;https://higherlogicdownload.s3.amazonaws.com/AFA/def574d3-a429-454b-a3e8-e5073c93ca6b/UploadedImages/MI%20DD%20Bomber%20final.pdf&quot; rel=&quot;noreferrer&quot;&gt;Beyond the &quot;Bomber&quot;: The New Long-Range Sensor-Shooter Aircraft and United States National Security&lt;/a&gt; - Lieutenant General David A. Deptula, USAF (Ret.), 2015.)&lt;/sup&gt;&lt;br&gt; The same was true with strike packages during Desert Storm, eg only a third of the aircraft dropped bombs while the rest provided support (jamming, anti-radiation, top cover, etc).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;We didn't build enough B-1s and B-2s to replace it, so we kept some B-52s to fill in the gaps (we don't have any other suitable heavy bombers in inventory, this is the &lt;em&gt;only&lt;/em&gt; choice).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 100 B-1Bs were just a stopgap until the B-2 showed up, of which we meant to build 132 (cut to 21 airframes). Had the Cold War continued, the B-2 would have comprised the bulk of today's bomber force.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;We were busy buying new fighters and cargo planes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The official, stated goal is to recapitalize the entire bomber fleet (less the B-2) because it's increasingly obsolete. That's worth repeating: &lt;em&gt;the B-1 and B-52 are near obsolete&lt;/em&gt;. They're not nearly capable enough. The next bomber isn't another B-1, B-52, or modded 747 because we don't want to maintain the &lt;em&gt;same&lt;/em&gt; capabilities. We want &lt;em&gt;more&lt;/em&gt; capability--much more--than what we currently have. We've only waited this long because &lt;a href=&quot;http://www.northropgrumman.com/AboutUs/AnalysisCenter/Documents/pdfs/The_2018_Bomber_the_case_for_a.pdf&quot; rel=&quot;noreferrer&quot;&gt;replacing the airlift and fighter fleets took priority&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The LRS-B (new stealth bomber; formerly NGLRS) will replace the B-52 starting around next decade. The contract is expected to be awarded very soon. The Pentagon &lt;a href=&quot;http://www.defensenews.com/story/breaking-news/2015/09/02/new-air-force-bomber-testing-stealth-wind-test/71572050/&quot; rel=&quot;noreferrer&quot;&gt;briefed a select group earlier this month&lt;/a&gt;. Looks very promising---well managed, on budget, very capable, and surprisingly mature. &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;: The B-21 (ex-LRS-B, ex-NGLRS) was indeed awarded 27 Oct 2015, a month and a half after this post was originally written. Very little is known, but it is indeed a stealthy bomber (the official render closely resembles the outer mold line of early B-2 iterations before the redesign). And it is indeed on time and under budget by ~9% (APUC = &lt;a href=&quot;http://www.af.mil/News/Article-Display/Article/626131/air-force-awards-lrs-b-contract/&quot; rel=&quot;noreferrer&quot;&gt;\$511M&lt;/a&gt; vs. the \$550M requirement, FY10\$).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In short, we still fly the B-52 today because we don't have a choice, not because we want to.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Parting thoughts&lt;/strong&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I want to emphasize that the B-52 did &lt;em&gt;not&lt;/em&gt; remain effective in its intended role (penetrating the USSR on Day 1), upgrades notwithstanding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, the B-52 survived multiple replacements (eg XB-70, B-1A), but not because it was more capable (it wasn't; the B-70/1A went higher/faster/lower/with more payload), but because those potential replacements couldn't outpace Soviet defenses &lt;em&gt;either&lt;/em&gt; and so were cancelled in favor of ballistic missiles and cruise missiles... except the B-2, which &lt;em&gt;could&lt;/em&gt; outpace Soviet defenses but was curtailed when those Soviet defenses disappeared. The B-52 survived basically because of luck: against the XB-70 and B-1A, it was the incumbent, already bought and paid for; against the B-2, history smiled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the B-52 did not &quot;survive&quot; the B-1B. The B-1B was never meant to replace all B-52s in the first place. The B-1B was meant to fill an urgent requirement as a stopgap from ~1985-1995 until the B-2 could enter service. Unlike previous B-52 would-be replacements, B-1B production was not cut short: 100 were ordered, and all 100 were delivered, essentially on time and on budget (&lt;a href=&quot;https://www.rand.org/pubs/notes/N3616.html&quot; rel=&quot;noreferrer&quot;&gt;though that was actually partly the problem&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully the B-52's range and payload kept it productive during its long service.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some background.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The USAF operates ~160 bombers:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;76 B-52s&lt;/li&gt;&#xA;&lt;li&gt;63 B-1s&lt;/li&gt;&#xA;&lt;li&gt;20 B-2s  &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2017-12-10T11:45:06.423" LastActivityDate="2017-12-10T11:45:06.423" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21259" PostTypeId="2" ParentId="21257" CreationDate="2015-09-26T04:27:34.983" Score="9" Body="&lt;p&gt;Those are not specifically STOL hardware, they are bungee covers that happen to have an airfoil shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft like the one in your picture use bungees (also called &quot;shock cords&quot;) to absorb the force of landing: As weight is transferred to the gear the bungees are stretched. The installed bungees look like this:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PFyVy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PFyVy.jpg&quot; alt=&quot;J3 Cub Bungee installation/removal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bungees are literally just &quot;aviation-grade&quot; &lt;a href=&quot;https://en.wikipedia.org/wiki/Bungee_cord&quot; rel=&quot;noreferrer&quot;&gt;bungee cords&lt;/a&gt;, and would be quickly deteriorated by weather if left exposed, so they are usually covered. The most basic covering is a leather or plastic boot:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ASgKd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ASgKd.jpg&quot; alt=&quot;&amp;quot;Bungee boots&amp;quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The boots are not much more aerodynamic than the exposed bungees however, so some aircraft (including many with STOL kits) have a cover with an aerodynamically favorable shape to reduce the drag caused by the bungee bulge. That style of cover is what's shown in your picture.&lt;br&gt;&#xA;Here's a closer look:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/061jN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/061jN.jpg&quot; alt=&quot;Airfoil bungee covers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-26T04:27:34.983" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21261" PostTypeId="2" ParentId="21254" CreationDate="2015-09-26T11:40:02.830" Score="8" Body="&lt;p&gt;My copy of &quot;EW 101: A First Course in Electronic Warfare&quot; calls it &quot;&lt;strong&gt;formation jamming&lt;/strong&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/05SHX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/05SHX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mind you, an operator of a radar with non-cooperative threat recognition capability will at least suspect something is wrong (although not from all aspects and ranges). &lt;/p&gt;&#xA;" OwnerUserId="337" LastEditorUserId="337" LastEditDate="2015-09-26T11:46:19.533" LastActivityDate="2015-09-26T11:46:19.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21262" PostTypeId="1" CreationDate="2015-09-26T11:56:51.803" Score="18" ViewCount="4199" Body="&lt;p&gt;I was reading about &lt;a href=&quot;https://en.wikipedia.org/wiki/TACA_Flight_110&quot; rel=&quot;noreferrer&quot;&gt;TACA Flight 110&lt;/a&gt; that amde a successful emergency landing on a New Orleans levee and I found out that the Pilot in Command was blind in one eye.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just curious, under current FAA rules would such a pilot be able to get the Airman's Medical Certificate needed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a &lt;a href=&quot;https://aviation.stackexchange.com/q/9497/62&quot;&gt;related question&lt;/a&gt;, but that only discusses getting a PPL and even there the responses are quite skeptical. And here we're talking about a CPL, or more accurately a type-certified ATPL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have regulatory regimes become stricter? Even if the rules allowed it, would risk-averse/litigation-averse airline companies allow it? Are there other cases known?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-26T17:49:04.943" Title="Can one become a scheduled airline pilot with just one functional eye?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21263" PostTypeId="2" ParentId="21256" CreationDate="2015-09-26T12:09:32.443" Score="7" Body="&lt;p&gt;I suppose with &lt;a href=&quot;https://en.wikipedia.org/wiki/Paramotor&quot; rel=&quot;nofollow noreferrer&quot;&gt;paramotor&lt;/a&gt; you mean a powered paraglider, as pictured below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qLx9n.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qLx9n.jpg&quot; alt=&quot;Paramotor&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paramotor (picture &lt;a href=&quot;http://footflyer.com/Articles/News/2009/PalmBayPilotFlying.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since they obey the same laws of physics, they also stall, just like a fixed-wing aircraft does. There are, however, some peculiarities which should be mentioned:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The shape of the wing is produced by ram air filling the &lt;a href=&quot;https://en.wikipedia.org/wiki/Parafoil&quot; rel=&quot;nofollow noreferrer&quot;&gt;parafoil&lt;/a&gt;, so speed will help to keep the wing inflated and in shape. At low speed and in gusty winds the risk of the parafoil collapsing (severe deflation) is higher. This was the reason for several fatal accidents in the early times of paragliders, when the aspect ratio of high-performance parafoils was increased beyond safe limits. Today's designs will normally quickly recover from a deflation event, but not without a substantial loss of altitude.&lt;/li&gt;&#xA;&lt;li&gt;The pressure forces on the parafoil will change its shape depending on its angle of attack. At low speed the angle of attack is higher, resulting in a suction peak close to the leading edge which in turn will increase the local camber of the foil. This leads to severe lift loss in a stall, and recovery needs some altitude. A fixed-wing aircraft, on the other hand, can employ an airfoil with only little lift loss in a stall, so recovery needs less altitude. This is by no means universal - there are also fixed-wing aircraft with less benign stall characteristics.&lt;/li&gt;&#xA;&lt;li&gt;If the stall on a fixed wing starts near the wing tip, the aircraft might enter an uncontrollable roll. This can happen in steep turns and with badly designed aircraft. This is not possible in a parafoil; it might instead slide sideways with a partially collapsed parafoil, but stay upright due to its low center of gravity. If the pilot panics and pulls his brake lines on one side during a stall, the parafoil can enter a spin. Similarly, if the pilot of a fixed-wing aircraft insists on applying rudder when stalled, the aircraft can also enter a spin.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Generally, due to their low wing loading and the drag of the raiser lines, paramotors fly at much lower speeds than aircraft, so accidents involve less energy, but the pilot has no protection around her/him, so fatal accidents do occur more regularly than with fixed-wing aircraft. For paragliders, Wikipedia gives a number of 2 fatalities per year for 10.000 pilots.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-09-27T21:09:12.730" LastActivityDate="2015-09-27T21:09:12.730" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21264" PostTypeId="1" AcceptedAnswerId="24072" CreationDate="2015-09-26T14:13:47.547" Score="3" ViewCount="410" Body="&lt;p&gt;I'm doing a problem on Flight Mechanics in which a banked turn is performed. The center of gravity of the aircraft is always within an horizontal plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to write the dynamic equations, I have to assume some simplifications and conditions. One of them is the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The thrust’s sideslip angle is equal and with opposite sign than the aeroplane’s sideslip angle, that is: &#xA;  ($\nu = −\beta$).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Side slip angle ($\beta$) is defined as the angle made by the velocity&#xA;  vector to longitudinal axis of the vehicle at the center of gravity in&#xA;  an instantaneous frame.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Thrust side slip angle ($\nu$) is defined as the angle made by the&#xA;  thrust vector to longitudinal axis of the vehicle at the center of&#xA;  gravity in an instantaneous frame.&#xA;  &lt;a href=&quot;https://en.wikipedia.org/wiki/Slip_(aerodynamics)#Sideslip_angle&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Slip_(aerodynamics)#Sideslip_angle&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Then, I have to write the dynamic equations for the symmetric flight and for the non-symmetric flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In my opinion, the condition written above should not be accounted for the &lt;strong&gt;symmetric flight&lt;/strong&gt;, so $(\beta = \nu = 0)$. Is this affirmation correct?&lt;/li&gt;&#xA;&lt;li&gt;For the non-symmetric case, I have drawn the following scheme of velocity and thrust. But I'm not sure if it's correct because it doesn't make sense, despite that is what the condition says: $(\nu=-\beta)$. &lt;strong&gt;Is the scheme correct according to the condition?&lt;/strong&gt; (The scheme is the top view of the aircraft.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GJUhs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GJUhs.jpg&quot; alt=&quot;Thrust-speed scheme.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="22726" LastEditDate="2019-10-08T03:58:06.773" LastActivityDate="2019-10-08T03:58:06.773" Title="In a non-symmetric turn, how do the side slip angle and thrust side slip angle affect the equations of motion?" Tags="&lt;aircraft-physics&gt;&lt;sideslip&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="21265" PostTypeId="1" CreationDate="2015-09-26T14:23:08.793" Score="9" ViewCount="401" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XsP7N.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XsP7N.png&quot; alt=&quot;Tumanosky R-13 casing treatment&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The images show a kind of casing treatment used in Russian aero-engines.&lt;br/&gt;&#xA;From what I have found out the first engine featuring this kind of casing treatment was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tumansky_R-13&quot; rel=&quot;noreferrer&quot;&gt;Tumansky R-13&lt;/a&gt;. Since then it was used in numerous Russian jet-engines (e.g. &lt;a href=&quot;https://en.wikipedia.org/wiki/Tumansky_R-29&quot; rel=&quot;noreferrer&quot;&gt;Tumansky R-29&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Klimov_RD-33&quot; rel=&quot;noreferrer&quot;&gt;Klimov RD-33&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bzjfT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bzjfT.png&quot; alt=&quot;Tumanosky R-13 casing treatment&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8mF2p.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8mF2p.png&quot; alt=&quot;Tumanosky R-13 casing treatment&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6h8e2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6h8e2.png&quot; alt=&quot;Tumanosky R-13 casing treatment&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Casing treatments are usually used to increase the operating range of compressors. And there exists a wide range of different types/geometries of casing treatments:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jl01q.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jl01q.png&quot; alt=&quot;Hathaways VKI Lecture Series talk&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was not able to find any documentation or publication on the working principle of the Russian casing treatments and how they were designed. Since they were designed in the 1950s their design was likely done by correlations. The interesting thing is that the design of the 1970s looks very comparable so the advances in 1. computing power and 2. operating experience did not change them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone have information on:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The design rules for these casing treatments (stagger angle, skew angle, axial position)?&lt;/li&gt;&#xA;&lt;li&gt;The working principle or intent (recirculation, blowing, sucking)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11294" LastActivityDate="2016-04-01T20:26:41.367" Title="What is the purpose of those casing treatments and how were they designed?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;engine&gt;&lt;jet&gt;&lt;propulsion&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21266" PostTypeId="2" ParentId="21246" CreationDate="2015-09-26T14:45:04.780" Score="7" Body="&lt;p&gt;One thing to note is that 'pure' air dominance fighter or ground attack aircraft is not being developed anymore. Most of the combat aircraft developed recently/under development are multirole (or 'omnirole') aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of air dominance (or air superiority) fighters, which have the task of eliminating enemy air defense system especially fighters and securing aerial control for operation of friendly forces without harassment, the following are important design objectives:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High thrust to weight ratio, as it helps in maneuvers.&lt;/li&gt;&#xA;&lt;li&gt;Stealth, as the enemy can't shoot what he/she can't see.&lt;/li&gt;&#xA;&lt;li&gt;High maneuverability, for close combat situations and evasion. &lt;/li&gt;&#xA;&lt;li&gt;High weapons load, as it enables engagement of a large number of enemy aircraft at once.&lt;/li&gt;&#xA;&lt;li&gt;A good range, as it is better to engage enemy aircraft in their area rather than in friendly territory.&lt;/li&gt;&#xA;&lt;li&gt;A powerful radar to track and engage enemy aircraft, as it enables them to shoot first.&lt;/li&gt;&#xA;&lt;li&gt;Communication links to transfer data between the aircraft and between the AEWACS aircraft, as most of the aircraft today operate in an integrated battlefield.&lt;/li&gt;&#xA;&lt;li&gt;Speed is also a very important parameter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case of ground support (or attack) aircraft, whose primary task is the destruction of enemy logistics and/or support for ground troops under fire, the designers look for similar yet a bit different set of characteristics. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ruggedness, as the aircraft should be able take some amount of punishment and return home.&lt;/li&gt;&#xA;&lt;li&gt;High endurance and Time on Target, as the ground troops may require support for an extended period of time, with corresponding weapons load.&lt;/li&gt;&#xA;&lt;li&gt;Communication links between aircraft and ground troops for obvious reasons.&lt;/li&gt;&#xA;&lt;li&gt;Precision targeting systems for situations where friendlies are in close contact with the enemy troops.&lt;/li&gt;&#xA;&lt;li&gt;Ability to operate from forward operating bases is desirable.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most of the present generation aircraft carry out their ground support duties using precision weaponry rather than any fundamental design decisions. Though there are still trade-offs, as in any aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The weapon load of stealth aircraft is lesser their non-stealthy counterparts as external weapons carriage increases the radar signature of the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;For ground attack aircraft, a high subsonic speed is more than enough unlike the supersonic air dominance fighters.&lt;/li&gt;&#xA;&lt;li&gt;Low altitude maneuverability is important for ground attack aircraft for quick ingress and egress from the combat area. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;One aspect of aircraft design is that combat aircraft optimized for high altitude operations can face higher stresses when operating in lower altitudes (i.e. near ground). For example, when USAF switched B-52s from high altitude bombing role to low altitude penetration tactics, it caused increased stress in the airframe. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-26T14:45:04.780" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21268" PostTypeId="2" ParentId="14088" CreationDate="2015-09-26T16:04:10.023" Score="5" Body="&lt;p&gt;I fly for a commercial airline, which is different, bit I also fly light planes and as a CFI I flight instructed in them for hundreds of hours. In a nutshell, I taught if you were in flatland areas with no terrain/obstacles to clear, retract the flaps at 300-500 feet AGL in the climbout, as long as you have adequate airspeed and are accelerating. You then have to trim nose up a bit to keep the climb rate up due to the loss of flap lift. No need to over complicate this. In mountainous terrain, or in a canyon, or on very short fields with obstacles nearby or at high altitudes where performance is degraded, pilots often elect to delay flap retraction and gain better slow speed climb performance. Depends on the situation. Hope that helps!  Fly safe and have fun!&lt;/p&gt;&#xA;" OwnerUserId="11397" LastActivityDate="2015-09-26T16:04:10.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21269" PostTypeId="2" ParentId="21254" CreationDate="2015-09-26T16:53:20.930" Score="2" Body="&lt;p&gt;If two aircraft are flying one above the other, they are flying in &lt;em&gt;stacked&lt;/em&gt; formation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WKuH2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WKuH2.jpg&quot; alt=&quot;12 Aircraft stacked formation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;12 Aircraft stacked formation SOP of 303 Bombardment Group, from 303rdbg.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, it is about flying, with nothing said about radar deception. This technique was used in B-17 combat boxes in WWII, where aircraft squadrons were stacked at multiple altitudes. One advantage of this tight box like formations was that they presented the anti-aircraft gunners with smaller target.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-26T17:01:15.730" LastActivityDate="2015-09-26T17:01:15.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21270" PostTypeId="1" AcceptedAnswerId="21274" CreationDate="2015-09-26T16:56:09.060" Score="10" ViewCount="997" Body="&lt;p&gt;Pilots flying under the FAA jurisdiction have many official sources of weather information available to them. Specifically as it relates to icing conditions, what official sources of weather information can pilots refer to in order to avoid or mitigate the risk of flying in icing conditions?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="19" LastEditDate="2015-09-27T07:38:27.303" LastActivityDate="2016-02-04T18:09:07.527" Title="What FAA sources of weather information can pilots use to mitigate the risk of flying in icing conditions?" Tags="&lt;weather&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21271" PostTypeId="2" ParentId="21270" CreationDate="2015-09-26T17:30:31.383" Score="4" Body="&lt;p&gt;You can get it from Airmen's Meteorological Information or Significant Meteorological Information, a compiled graphical version of which can be found at &lt;a href=&quot;https://www.aviationweather.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Weather Center&lt;/a&gt;. FAA Advisory Circular 91-74A, &lt;em&gt;Pilot Guide: Flight In Icing Conditions&lt;/em&gt;, notes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aviation meteorologists at the NWS Aviation Weather Center (AWC), local NWS&#xA;  Field Offices, major airlines, and private companies prepare icing forecasts. In addition, guidance products are available on the Web. Icing AIRMETs, prepared at AWC, cover a 6-hour forecast window and are updated four times daily.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also it notes the importance of Pilot Reports (PIREP), &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PIREPs remain the major source of information for icing location and severity&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that FAA requires the weather sources to be &lt;a href=&quot;https://aviation.stackexchange.com/questions/1648/what-sources-of-weather-are-approved-by-the-u-s-national-weather-service?rq=1&quot;&gt;approved by US National Weather Service&lt;/a&gt;. As far as icing conditions go, to the best of my knowledge FAA doesn't mandate any particular source.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-09-26T17:42:24.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21272" PostTypeId="2" ParentId="21262" CreationDate="2015-09-26T17:45:31.750" Score="16" Body="&lt;p&gt;Under &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/et/31-34/mv/&quot; rel=&quot;nofollow noreferrer&quot;&gt;current FAA medical regulations&lt;/a&gt; a pilot with one functional eye (called &lt;em&gt;monocular vision&lt;/em&gt;) can get any class of medical, including the class 1 required for airline pilots:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An individual with one eye, or effective visual acuity equivalent to&#xA;  monocular, &lt;strong&gt;may be considered for medical certification, any class&lt;/strong&gt;,&#xA;  through the special issuance section of part 67 (14 CFR 67.401)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As the same page says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;it has been repeatedly demonstrated that binocular vision is not a&#xA;  prerequisite for flying&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Incidentally, one of aviation's most famous pioneers, &lt;a href=&quot;https://en.wikipedia.org/wiki/Wiley_Post&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wiley Post&lt;/a&gt;, had only one eye. As for today, it's legal and possible to get any class of FAA medical with only one eye and therefore in principle you could fly for any US airline. Whether or not an airline would hire you is a different question, but if you're legal and qualified then why not? Blindness in one eye isn't even &lt;a href=&quot;http://www.ssa.gov/pubs/EN-05-10052.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;considered a disability&lt;/a&gt; by the US government if the other eye is fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also possible that if an airline declined to hire you because of your monocular vision even if you hold an ATP and class 1 medical, you might have a case for suing them for discrimination. But that's speculation, and you would need to ask &lt;a href=&quot;https://law.stackexchange.com/&quot;&gt;another site&lt;/a&gt; about that. In any case, there may be more pilots out there than you think with physical limitations (for want of a better word), including ones with &lt;a href=&quot;http://avherald.com/h?article=478cc9e4&quot; rel=&quot;nofollow noreferrer&quot;&gt;prosthetic limbs&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T13:00:26.903" LastActivityDate="2015-09-26T17:45:31.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21273" PostTypeId="2" ParentId="9526" CreationDate="2015-09-26T20:07:03.063" Score="8" Body="&lt;p&gt;The relationship: non-linear. I know that at least for early jet engines (yes, I am that old.) 90% of the thrust was in the last 10% of RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These engines also spooled up slowly. We were told to fly approaches at 70% RPM, because at that RPM, there was essentially no thrust. To go from idle to 100% took about 5 -6 seconds: most of that time getting to about 70%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving the throttle forward fast meant watching the fuel flow go up, TIT increase and watch the RPM increase on time lapse photography.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Go-arounds had to be planned well in advance.&lt;/p&gt;&#xA;" OwnerUserId="11400" LastActivityDate="2015-09-26T20:07:03.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21274" PostTypeId="2" ParentId="21270" CreationDate="2015-09-26T22:09:10.300" Score="8" Body="&lt;p&gt;Here's a list of official FAA weather information sources that pilots can analyze to avoid or mitigate icing risks:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;AIRMET Zulu&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;An AIRMET Zulu will be issued for areas where icing conditions are forecast to be light or moderate.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;SIGMET&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;A SIGMET will be issued for icing conditions forecast to be severe.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;PIREPs&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;PIREPs are the best source of icing information. Unlike weather information sources which are forecasts, PIREPs are reports from pilots flying in the actual conditions and should be considered the most accurate source of icing information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example of a PIREP where a pilot of a TBM-700 was descending into Atlanta. He reported a cloud layer topping at 7900 feet down to 500 feet AGL and picking up light rime ice between 7900 and 5000 feet.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;UA /OV ATL /TM 1200 /FLUNKN /TP TBM7 /SK OVC015-TOP079 /IC LGT RIME 050-079 /RM DURD&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;h3&gt;Significant Weather Prognostic Charts&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The top two panes of a prog chart help pilots visualize the freezing level. A zig zag line shows when freezing level is at the surface and height contours for the highest freezing level are drawn at 4000 foot intervals with dashed lines. This information gives pilots a forecast of temperatures which when combined with known precipitation can predict ice and help to avoid it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/ruVgs8M.gif&quot; alt=&quot;prog chart&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Area Forecast (FA)&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;An FA is an additional source of information about where cloud tops and bottoms are. If you know that along with the freezing level you can get a better idea of where icing conditions are most likely.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2016-02-04T18:09:07.527" LastActivityDate="2016-02-04T18:09:07.527" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21275" PostTypeId="1" AcceptedAnswerId="21276" CreationDate="2015-09-26T23:40:48.517" Score="11" ViewCount="1691" Body="&lt;p&gt;For what reasons would a pilot want to file a PIREP? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot wanted to file a PIREP, how would he/she go about filing one?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-09-27T00:13:07.043" Title="How does a pilot file a PIREP?" Tags="&lt;weather&gt;&lt;pirep&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21276" PostTypeId="2" ParentId="21275" CreationDate="2015-09-27T00:13:07.043" Score="9" Body="&lt;p&gt;I'll tackle the &quot;How&quot; first - you call up Flight Service (either on the radio or on the phone after you land) and tell them you have a pilot report.  There's a &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/alaska/fai/inflight/media/PIREP_FORM.pdf&quot;&gt;standard format for pilot reports&lt;/a&gt;, and if you give all the information in the order it appears on that form it's faster for you and the person taking the report.&lt;br&gt;&#xA;If you're filing a pilot report on the ground for conditions you encountered enroute you need to specify the (Zulu) time of your observation (or tell the briefer &quot;20 minutes ago&quot;). In the air it's generally assumed your report is for &quot;now&quot;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pilots are requested to provide pilot reports for significant deviations from the forecast weather, or for hazardous conditions. Basically we provide them as a courtesy and service to our fellow pilots (like flashing your lights at other cars on the highway if you know there's a speed trap).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some pilot reports you may want to file in flight are if the Winds Aloft differ from the forecast. If the forecast told you you should have a 10 knot tailwind and you actually have a 5 knot headwind that's pretty significant, and if you tell Flight Service they will pass it along to the weather forecasters and they'll factor it in to their next Winds Aloft calculation. It will also appear in the next pilot's briefing so they'll know the winds in the forecast aren't correct.&lt;br&gt;&#xA;Another example is turbulence: If you're encountering continuous moderate chop at 7,000 feet but smooth air at 9,000 feet providing that information could be useful to the next pilot flying through the same area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A classic example of a PIREP you file after you're on the ground is icing: If there was no icing in the forecast but you've encountered some you should report these conditions. If you're under ATC control you'll obviously tell them, but when you're on the ground you should call Flight Service and file a formal pilot report. Again, the information will be passed to the weather forecasters and the icing AIRMET will be updated, and your PIREP will be passed along to other folks in their briefings to keep them out of the ice. &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-27T00:13:07.043" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21277" PostTypeId="1" AcceptedAnswerId="21278" CreationDate="2015-09-27T03:12:28.760" Score="10" ViewCount="4245" Body="&lt;p&gt;Wikipedia's &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-24&quot;&gt;Mi-24 Hind&lt;/a&gt; article (a Soviet helictoper) says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Heat dissipaters were also fitted to exhausts to decrease the Mi-24's heat signature.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's no citation. What exactly is a heat dissipater and how does it work?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2015-09-27T05:16:41.180" Title="What is a heat dissipater and how does it work?" Tags="&lt;military&gt;&lt;helicopter&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21278" PostTypeId="2" ParentId="21277" CreationDate="2015-09-27T04:38:57.383" Score="12" Body="&lt;p&gt;The heat dissipaters  are used to reduce the infra-red signature of the helicopter engine exhaust. They are also used in other helicopters, like the 'black hole ocarina' (BHO) infra-red suppression device used in AH-64 Apache.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5n9g3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5n9g3.jpg&quot; alt=&quot;Black hole infrared suppression system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: b-domke.de&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main purpose of the IR suppressors in use today is twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reduce the IR signature by reducing the exhaust temperature&lt;/li&gt;&#xA;&lt;li&gt;'Shield' the hot engine from view.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The infra-red suppression systems in service today usually work by&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;'Bending' the exhaust, usually upwards, and shielding the exhaust from view by an insulating cowl. In these IR suppressors in Mi- 35 (export version of Mi-24), the exhaust is turned almost 90°.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/atf6J.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/atf6J.jpg&quot; alt=&quot;Mi- 35 IR suppressors&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: mamboccv.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Mixing the hot engine exhausts with the cool air, effectively reducing the exhaust temperature. In the Black Hole IR suppression system, the exhaust temperature is reduced from ~600 °C to ~300 °C .&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The RAH-66 Comanche had the infra-red suppression system integrated into the airframe (the exhaust was routed through the tail boom), though the principle is the same- mixing of engine exhaust with ambient cool air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mZJvC.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mZJvC.png&quot; alt=&quot;RAH 66 IR suppression system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: sikorskyarchives.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In some cases, the special high emissivity coatings are applied to the engine exhausts for reducing the IR signature. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most of the present IR suppressors focus on achieving a thorough mix of the cool ambient air and the exhaust to reduce temperature and uneven mixing, in order to prevent 'hot spots'. Cooling of the exhaust pipe itself is achieved in some cases by using film cooling. In most helicopters, the infra red suppression system (IRSS) is optional and can be added separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The figure shows the schematic of the infrared suppression system used in AH- 64 Apache and the associated reduction in IR signature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XntUU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XntUU.jpg&quot; alt=&quot;Working of IR suppression System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Progress in helicopter infrared signature suppression&lt;/em&gt; by Jingzhou Zhang et al., Chinese Journal of Aeronautics, Volume 27, Issue 2&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-27T05:16:41.180" LastActivityDate="2015-09-27T05:16:41.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21280" PostTypeId="2" ParentId="9526" CreationDate="2015-09-27T07:53:19.010" Score="2" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;How does the engine RPM vary in this process?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is safe to say that in most operating conditions the shaft-speed will increase with higher thrust settings. Here is why:&lt;br/&gt;&#xA;When we look at a very simplified version of the processes in a jet-engine, increasing fuel-flow will increase temperature in the combustor. This will push point 4 to a higher T.&lt;br/&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9UMKY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9UMKY.png&quot; alt=&quot;https://www.grc.nasa.gov/www/K-12/airplane/brayton.html&quot; /&gt;&lt;/a&gt;&lt;br/&gt;&#xA;At first the turbine will consume the same amount of energy. This means the »distance« between point 4 and 5 will stay the same. Finally, this means the »distance« between point 5 and point 8 is bigger. In a T-S-diagram the distance is a measure of energy stored in the air, so there is more energy in the air exiting the nozzle so the jet will be faster and this will increase the airspeed. BUT, another thing is happening as well, actually it is happening simultaneously but a bit slower: since the air is hotter at the turbine entry the turbine will also extract more energy from the hot air and will therefore speed up. Which leads to a higher speed in the compressor as well, which leads to your second question.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Is there an equation which binds together spool RPM to the thrust?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The short answer is: No&lt;br/&gt;&#xA;But, actually it is not that easy. There exits no single equation for the engine but a system of equations. The character of this system is non-linear an holds a large number of parameters (e.g. compressor- and turbine-efficiency curves) which are sometimes unknown and need to be measured during an experiment.&lt;br/&gt;&#xA;However, it is possible to perform experiments and reduce the number of parameters and build correlations. Which is done regularly in order to model engine performance or control the engine.&lt;br/&gt;&#xA;I am not entirely sure what kind of »equations« you were referring to in your question. Because in principle correlations are equations as well but one needs to fit those correlations based on experiments to determine the parameters which you cannot know in advance.&lt;/p&gt;&#xA;&lt;p&gt;The above is a very simplified view on a jet-engine. Depending on the type on jet-engine there are a lot more settings which influence the engine-behaviour: for example the Variable-Guide-Vane-Actuation-Law, or the Bleed-Air-Schedule, or the Cooling-Sytem of the casing. They all contribute to the complexity which make a »simple equation« impossible.&lt;/p&gt;&#xA;" OwnerUserId="11294" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-27T08:00:10.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21281" PostTypeId="1" CreationDate="2015-09-27T10:48:30.613" Score="6" ViewCount="711" Body="&lt;p&gt;On a lot of aircraft, the model number / aircraft name is clearly marked somewhere on the fuselage, e.g. &quot;Airbus A320&quot;. Is there any rule or mandate, that all aircraft must bear the model number at some designated place on its body, to help others identify them?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="946" LastEditDate="2015-09-27T20:33:38.680" LastActivityDate="2019-04-14T02:40:58.640" Title="Are commercial aircraft required to have the model number painted on them?" Tags="&lt;regulations&gt;&lt;fuselage&gt;&lt;livery&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21282" PostTypeId="1" AcceptedAnswerId="21287" CreationDate="2015-09-27T13:25:58.163" Score="2" ViewCount="546" Body="&lt;p&gt;I was watching this video &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/D30oGBj08Vs?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; and just curious about the legality. Would it just fall under 91.119(a) operation of an aircraft 'anywhere' &lt;/p&gt;&#xA;" OwnerUserId="11356" LastEditorUserId="946" LastEditDate="2015-12-31T10:21:32.143" LastActivityDate="2015-12-31T10:21:32.143" Title="Would the flyby in this video be illegal under 91.119(a)?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21283" PostTypeId="2" ParentId="21237" CreationDate="2015-09-27T15:30:29.210" Score="1" Body="&lt;p&gt;From all the NASA reports I could find they mostly use &lt;a href=&quot;https://en.wikipedia.org/wiki/Thermocouple&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thermocouples&lt;/a&gt;. They also use &lt;a href=&quot;https://en.wikipedia.org/wiki/Resistance_thermometer&quot; rel=&quot;nofollow noreferrer&quot;&gt;RTDs&lt;/a&gt; which sometimes are called &lt;em&gt;PT100&lt;/em&gt;. I am not sure if termistors are used.&#xA;There is research on optical measurement, but right now I would say that &lt;em&gt;Thermocouples&lt;/em&gt; and &lt;em&gt;RTDs&lt;/em&gt; are the common way to measure EGT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MhEZS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MhEZS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800014827.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://ntrs.nasa.gov/archive/&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.grc.nasa.gov/WWW/sensors/PhySen/docs/AIAA3923_JPC2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.grc.nasa.gov/WWW/sensors/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11294" LastActivityDate="2015-09-27T15:30:29.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21284" PostTypeId="1" CreationDate="2015-09-27T15:35:49.607" Score="2" ViewCount="85" Body="&lt;p&gt;I was watching a commercial jet and the vapor trail was moving and disappearing very quickly. I should note that it is currently 61 F on the ground, but the morning has been cool. (Min 34 F) I don't know what vapor trails do under certain conditions, but I would assume that in warmer weather the vapor trail would completely disappear more quickly, but that doesn't seem to be the case in the summer. Anyway, the weird part was when the vapor trail completely disappeared or cut off. The plane stopped producing a trail for about 15 seconds and the plane was hard to see during this period. After that the trail reappeared and resumed as normal. I also noticed that the trail hung around much longer and dispersed more than all the other trails from planes that recently flew by. Perhaps the plane entered an area of air that was different in temperature than the air around it. Has anyone seen or heard of this and have any idea why this would happen?&#xA;Thanks&lt;/p&gt;&#xA;" OwnerUserId="8450" LastActivityDate="2015-09-27T15:35:49.607" Title="Vapor trail disappears then reappears" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;weather&gt;&lt;jet&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-09-28T15:57:31.617" ContentLicense="CC BY-SA 3.0" />
  <row Id="21285" PostTypeId="2" ParentId="19604" CreationDate="2015-09-27T15:37:09.757" Score="1" Body="&lt;p&gt;Well F-16s are old but will fly till 2045 here's how:&#xA;USAF loves those fighter that are fast,agile,advanced and cheap F-16 has all of them but not advanced so USAF is planning a new production line for F-16&#xA;Which is known the F-16V&#xA;Prototype will be completed in 2016 but F-16 will be even advanced than F-35. Lockheed has given these words&#xA;In addition F-16V will be supermanueverable like sukoi and F-22 without thrust vectoring nozzles &lt;/p&gt;&#xA;" OwnerUserId="11409" LastActivityDate="2015-09-27T15:37:09.757" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21286" PostTypeId="1" AcceptedAnswerId="21291" CreationDate="2015-09-27T15:56:41.093" Score="0" ViewCount="244" Body="&lt;p&gt;As I know, passangers on most international airports aren't allowed to take any fluid with them into the deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, for example, I can't remember for any deeper examination for nitrate- or peroxide compounds. Although they had been much dangerous, as a glass of water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it so?&lt;/p&gt;&#xA;" OwnerUserId="7794" LastEditorUserId="57" LastEditDate="2015-09-27T19:54:45.303" LastActivityDate="2015-09-27T19:54:45.303" Title="Why fluids are forbidden in flights, while nitrate- and peroxide compounds aren't?" Tags="&lt;commercial-aviation&gt;&lt;terrorism&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-09-28T16:43:26.657" ContentLicense="CC BY-SA 3.0" />
  <row Id="21287" PostTypeId="2" ParentId="21282" CreationDate="2015-09-27T16:02:57.657" Score="8" Body="&lt;p&gt;This depends how you look at it but there are definitely some FARs this guy is in breach of. First one that comes to mine is 91.119 on minimum altitudes, it's pretty straightforward (assuming this is an area other than congested area)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Except when necessary for takeoff or landing, no person may operate an aircraft below the following altitudes:&lt;/p&gt;&#xA;&lt;p&gt;(a) Anywhere. An altitude allowing, if a power unit fails, an emergency landing without undue hazard to persons or property on the surface.&lt;/p&gt;&#xA;&lt;p&gt;(c) Over other than congested areas. An altitude of 500 feet above the surface, except over open water or sparsely populated areas. In those cases, the aircraft may not be operated closer than 500 feet to any person, vessel, vehicle, or structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;He is pretty clearly within 500 ft of that person...&lt;/p&gt;&#xA;&lt;p&gt;You can see that there is a case for sparsely populated areas but I would argue that if there is a backyard party going on this is not a sparsely populated area.&lt;/p&gt;&#xA;&lt;p&gt;Then as mentioned there is the catch all in.13&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§91.13   Careless or reckless operation.&#xA;(a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I'd say that's reckless but of course that's up for debate. Then again it's impossible to say where this happened so we can't know what type of airspace this is in and if there were possible issues there. I would go on to say that at an altitude that low I would turn on my landing light to increase awareness and enable me to see the ground better.&lt;/p&gt;&#xA;&lt;p&gt;If you really want to push it you could even go as far as saying that maneuver is aerobatic flight since it's an abnormal attitude (at the altitude it's being performed) and most likely not seen in normal flight. For the record that attitude looks to be about around 30 degrees which would be a standard steep turn (something I would never attempt that close to the ground).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you think it fits under this definition the pilot is also in breach of 91.303&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No person may operate an aircraft in aerobatic flight—&lt;/p&gt;&#xA;&lt;p&gt;(b) Over an open air assembly of persons;&lt;/p&gt;&#xA;&lt;p&gt;(e) Below an altitude of 1,500 feet above the surface;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I would consider a backyard party (as described in the video description) as an open air assembly of persons and he is clearly below 1500 ft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;The Counter Point:&lt;/strong&gt; While the above points make a pretty solid case for the FAR's broken in the video, in theory if the maneuver is pre agreed upon, planned out, and executed as planned it may not be considered reckless. In the end of the day as a pilot you live at the mercy of the FAA and their decisions. In this case I would be most worried about that guy running into the propellor. I'm sure things like this happen more often than not.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditorDisplayName="user5664" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-31T06:22:07.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21289" PostTypeId="1" AcceptedAnswerId="21297" CreationDate="2015-09-27T17:42:02.133" Score="30" ViewCount="31960" Body="&lt;p&gt;In the event of a total failure of the tail rotor, is it possible to maneuver a helicopter to an emergency landing spot that is within, say, 30 minutes flying time? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the maneuvers required for a pilot to fly reasonably straight, and how do the aerodynamics work?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="62" LastEditDate="2019-05-24T04:53:01.777" LastActivityDate="2020-04-16T11:36:32.633" Title="If a helicopter's tail rotor fails, is it possible to perform an emergency landing?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;helicopter&gt;" AnswerCount="11" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21290" PostTypeId="2" ParentId="21289" CreationDate="2015-09-27T18:25:44.663" Score="31" Body="&lt;p&gt;Yes, but you certainly could not fly for 30 minutes since to do so, you would need power and if you use power, you will spin with no way of stopping it. Apart from a catastrophic failure, this is probably the hardest thing to get right.  A tail rotor failure on approach or &lt;a href=&quot;https://www.youtube.com/watch?v=5kXUZQYFu18&quot;&gt;in a high hover&lt;/a&gt; or with speed close to the ground is probably not going to end well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The correct recovery is to enter auto rotation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this removes the torque from the rotor, the fuselage will not spin apart from that caused by drag in the transmission system which can be countered by keeping speed up and using a little opposite cyclic. The tail boom and vertical stabiliser will tend to keep the aircraft straight whilst there is significant forward speed.  Any tendency to spin is opposed by the air flow striking the tail boom and fin on the side opposite to the spin and correcting it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=z3oVw6_0MEU&quot;&gt;The problem comes from the landing&lt;/a&gt; since you cannot balance torque as you raise collective and increase lift (and therefore drag which increases torque) to arrest the descent.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution is to tweak the throttle to control torque.  However, a high speed run on landing is inevitable.  Hope for a strong wind that you can land into since this will reduce the touch down speed and help to keep the approach and touchdown straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a hover, roll off the throttle and keep it there then perform a hovering autorotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both cases, keeping the throttle rolled off is the key.  If you bring significant power from the engine back into the rotor system, you will spin uncontrollably.  Small amounts of throttle, rolled rapidly on and off can be used to control torque as can use of collective during the descent of an autorotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this one never happens to me.  Engine failure doesn't particularly worry me, nor do &quot;stuck pedals&quot; but a tail rotor failure would not put a smile on my face.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-27T19:30:16.790" LastActivityDate="2015-09-27T19:30:16.790" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21291" PostTypeId="2" ParentId="21286" CreationDate="2015-09-27T18:57:15.853" Score="9" Body="&lt;p&gt;First of all, your statement, that it's not allowed to bring any liquid (gels, spray cans, ...) with you on most airports is simply not true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the EU, any liquid must be in containers of not more volume than 100ml, and all containers must be in a transparent, close-able plastic bag of not more than 1000ml.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, the rule is the same, but the limits are a bit lower for smoother numbers, like 3 fluid ounces (~90ml) and 30 fluid ounces (~900ml). (&lt;em&gt;I'm not absolutely sure about this values...&lt;/em&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason behind this is... not very clear. There is a big anti-terrorism stamp on this rule, but if you question the rule, there is no reasonable answer. You can bring enough toxic substance in that bag to kill everyone on board, or even explosives to put the aircraft down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ask me, the entire rule is there because the authorities wanted to make a rule to demonstrate that they are taking action. Remember that liquid baby food and personal medicine is excluded from the rule. Do you think terrorists would not abuse these exceptions? I still think this was the biggest coup ever of cosmetics and plastic bag sellers... (The latter could advertise explosion-proof bags... )&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Sorry, I went a bit off-topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, it's easy to check carry-on luggage for liquids, as they (or their cans) are clearly visible on X-rays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Explosive or oxidative material like your nitrate- or peroxide compounds are also in general banned from aircraft, from carry-on as well as from checked baggage.&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, they are hard to see on X-rays, especially if you put them into a less obvious shape. Manual inspection of your luggage would be the only way to search for these substances. In case of doubt, the staff at the safety check can do a wipe test, which means they wipe a small, special card over your carry-on (also from inside, and may be, they also check you). The card is then inserted into an analysis device, which can identify traces of forbidden substances, like explosives and drugs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture of a wipe test, with the analyzer in the background:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Iu7gN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Iu7gN.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Demonstration of wipe test. Source: &lt;a href=&quot;http://noe.orf.at/news/stories/2724009/&quot; rel=&quot;noreferrer&quot;&gt;http://noe.orf.at&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember flying from Zürich with a bag full of electronics. (Laptop, Laptop charger, mouse, another mouse, headphones, camera, camera charger, camera-to-laptop-cable, custom PCB, ...) and they did a very, very, really very careful wipe test.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2015-09-27T18:57:15.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21293" PostTypeId="1" CreationDate="2015-09-27T19:33:14.833" Score="15" ViewCount="3292" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Coaxial_rotors&quot;&gt;Coaxial Helicopters&lt;/a&gt; have two main rotor sets, one on top of the other, spinning in different directions to eliminate the need for a tail rotor. I've heard it said they're also more maneuverable, all else being equal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how is auto-rotation different (if anything) for these kinds of helicopters? Is it any easier? Do you get longer range and/or slower (safer) descent speed?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2016-03-18T23:54:44.737" Title="How is auto-rotation different in coaxial rotor helicopters?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21294" PostTypeId="2" ParentId="16314" CreationDate="2015-09-27T19:56:53.407" Score="0" Body="&lt;p&gt;I have learned of an organization that calls itself the &lt;a href=&quot;https://www.iac.org/&quot; rel=&quot;nofollow&quot;&gt;International Aerobatics Club&lt;/a&gt;.  It seems to be a US-based competition group, which prepares teams for international competitions.&lt;/p&gt;&#xA;" OwnerUserId="57" LastActivityDate="2015-09-27T19:56:53.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21295" PostTypeId="2" ParentId="21281" CreationDate="2015-09-27T20:25:29.237" Score="1" Body="&lt;p&gt;No. It's easy enough to find photographs online of aircraft that don't have the model number written on them in an obvious way. If there were any regulatory requirement to have the model number painted on the plane for recognition purposes, it would have to be obviously visible or there'd be no point.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2015-09-27T20:25:29.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21296" PostTypeId="1" AcceptedAnswerId="21298" CreationDate="2015-09-27T22:52:23.950" Score="7" ViewCount="2568" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/21270/8730&quot;&gt;This question&lt;/a&gt; was asked yesterday about sources of wx info. The answers focused on sources for pre-flight planning. As weather changes constantly pilots need current wx info en route, especially on long flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wx radar aircraft are equipped with can show what they are approaching for the next several miles, but often pilots need to know what is in their path much further ahead than what onboard radar can show.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1481/8730&quot;&gt;This question&lt;/a&gt; asks about in-flight wx info via cellular connection. The answers all allude to the unreliability and possible illegality of cellular use. However, in the comments several people suggested sources available through satellite and FIS-B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was reading &lt;a href=&quot;http://blog.foreflight.com/2015/08/14/oh-hail-cockpit-weather-delta-1889/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this blog post&lt;/a&gt; relating to the recent &lt;a href=&quot;http://www.cnn.com/2015/08/08/us/delta-emergency-landing-hail/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Delta flight&lt;/a&gt; which suffered severe hail damage after flying into a storm. The author decries the lack of weather info sources available to commercial pilots in-flight. He says, &quot;a pilot flying a single engine Cessna 172 can have significantly more weather information available to them in the cockpit than the crew of this A320 had.&quot; The author of the blog post is advocating for airlines to provide this info.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With many airliners now equipped with wifi it seems a pilot could have access to any number of ground-based NEXRAD radar services through a tablet or their EFB. What is there preventing commercial pilots from using these services? Is there an FAA rule that prohibits this or do airlines have rules as to where they can get their weather info?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-09-27T23:45:21.607" Title="What in-flight weather info is available to commercial pilots?" Tags="&lt;weather&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21297" PostTypeId="2" ParentId="21289" CreationDate="2015-09-27T23:11:42.200" Score="37" Body="&lt;p&gt;Although I used to think this was impossible, I now believe this can be done using weathervaning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a fast enough forward speed, the airflow will naturally keep the helicopter facing in that direction. For an example of someone doing this in reality, for an almost identical time period that OP requested, see this link:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&amp;amp;objectid=10493099&quot;&gt;http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&amp;amp;objectid=10493099&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the link, he needed to maintain 80 knots forward speed to prevent it from rotating out of control. Note whether this is possible may well depend on the weathervaning charactistics of the particular helicopter.&lt;/p&gt;&#xA;" OwnerUserId="11415" LastActivityDate="2015-09-27T23:11:42.200" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21298" PostTypeId="2" ParentId="21296" CreationDate="2015-09-27T23:45:21.607" Score="8" Body="&lt;h3&gt;Air Traffic Control&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Air Traffic Control (ATC) are often a major source of weather information for pilots. Modern ATC radars often overlay weather radar over the screen so ATC can assist pilots in avoiding weather. In terminal areas ATC may be equipped with additional systems such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Terminal_Doppler_Weather_Radar&quot; rel=&quot;nofollow noreferrer&quot;&gt;terminal doppler weather radar&lt;/a&gt; (TDWR) or &lt;a href=&quot;https://en.wikipedia.org/wiki/Low_level_windshear_alert_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;low-level windshear alert system&lt;/a&gt; (LLWAS). If able, ATC will impart any weather information they have to pilots to assist them in choosing the safest course. That's an ideal scenario of course and sometimes ATC isn't helpful.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;En Route Flight Advisory Service (EFAS or Flight Watch)&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A service specifically designed to provide timely en route&#xA;  weather information upon pilot request is known as the en&#xA;  route flight advisory service (EFAS), or Flight Watch. EFAS&#xA;  provides a pilot with weather advisories tailored to the type&#xA;  of flight, route, and cruising altitude. EFAS can be one of&#xA;  the best sources for current weather information along the&#xA;  route of flight.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A pilot can usually contact an EFAS specialist from 6 a.m. to 10&#xA;  p.m. anywhere in the conterminous United States and Puerto&#xA;  Rico. The common EFAS frequency, 122.0 MHz, is established&#xA;  for pilots of aircraft flying between 5,000 feet above ground&#xA;  level (AGL) and 17,500 feet mean sea level (MSL).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h3&gt;Hazardous Inflight Weather Advisory (HIWAS)&lt;/h3&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hazardous Inflight Weather Advisory (HIWAS) is a national&#xA;  program for broadcasting hazardous weather information&#xA;  continuously over selected navigation aids (NAVAIDs). The&#xA;  broadcasts include advisories such as AIRMETS, SIGMETS,&#xA;  convective SIGMETS, and urgent PIREPs. These broadcasts&#xA;  are only a summary of the information, and pilots should&#xA;  contact a FSS or EFAS for detailed information. NAVAIDs&#xA;  that have HIWAS capability are depicted on sectional charts&#xA;  with an “H” in the upper right corner of the identification&#xA;  box.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;img src=&quot;https://i.imgur.com/2Udo0k8.png&quot; alt=&quot;hiwas&quot;&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h3&gt;XM&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Many modern avionics systems receive &lt;a href=&quot;https://en.wikipedia.org/wiki/NEXRAD&quot; rel=&quot;nofollow noreferrer&quot;&gt;NEXRAD&lt;/a&gt; over XM as well as a myriad of other weather sources. Avionics suites such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Garmin_G1000&quot; rel=&quot;nofollow noreferrer&quot;&gt;Garmin G1000&lt;/a&gt; give pilots access to NEXRAD overlay over a map as well as a visual display of METARs, TAFs, FDs, PIREPs and many other weather information sources. There were a lot of acronyms there, but they can all be referenced in the two references provided at the bottom of this answer.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;On-board Radar&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Many aircraft are equipped with radar on-board. This provides a major step up from NEXRAD for making specific choices. Some pilots may disagree, but I view NEXRAD as a way to make &quot;overview&quot; choices about weather. NEXRAD is often too far delayed or affected by errors to make fine-grain choices. On-board radar can be directed at the airplane's altitude and provides an immediate picture of what's happening.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/BnSEvJv.jpg&quot; alt=&quot;on board radar&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I also read the article from ForeFlight about the Airbus that got into hail. It's true that many general aviation aircraft have more in the cockpit that airliners. I'm not sure if airline pilots are allowed to use additional sources from things like ADS-B receivers they bring with them, but my guess is that while it's probably not forbidden, it's a risk to the pilot. If a situation arose where a pilot made a decision based on information from an unofficial source and it lead to a bad result it could be detrimental for the pilot and the airline. Most pilots probably stick to their official sources.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For pilots flying under the FAA, two good sources for the answer are the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; (PHAK) Chapter 13 and &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/215166&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 00-45G&lt;/a&gt;. Chapter 13 of the PHAK is dedicated to aviation weather services, many of chich are available in flight. AC 00-45G is dedicated to the same, it just tends to be updated a little more often and goes into greater detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking though I have found that FAA materials haven't done the best job in keeping up with the fast pace of technology and its modernizing effects on avionics. Then again, the modern technologies are usually repackaging existing weather services and providing them in a better interface.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-09-27T23:45:21.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21299" PostTypeId="1" AcceptedAnswerId="21303" CreationDate="2015-09-28T00:37:33.340" Score="16" ViewCount="32071" Body="&lt;p&gt;I recently watched a movie and in the movie it stated that the helicopter could not fly to the top of mt.everest to rescue the person stuck on the top. So why can't helicopters fly at such high altitudes?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1360" LastEditDate="2020-01-05T19:30:50.873" LastActivityDate="2020-01-06T16:42:14.877" Title="Why can't helicopters fly at high altitudes?" Tags="&lt;aircraft-performance&gt;&lt;helicopter&gt;&lt;high-altitude&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21301" PostTypeId="2" ParentId="21299" CreationDate="2015-09-28T02:15:02.777" Score="10" Body="&lt;p&gt;The helicopter flies as long as the blades produce lift. Now,the lift is proportional to the density at a particular altitude. However, as altitude increases, the density goes down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, the helicopter compensates for this by increasing the lift coefficient by increasing the blade pitch (as the blade rotational speed, and hence V is constant). However, at a certain altitude, the maximum lift coefficient of the blades is reached and no further increase in lift is possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, the helicopter cannot fly beyond this altitude. This is the absolute ceiling of the helicopter.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-28T02:15:02.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21303" PostTypeId="2" ParentId="21299" CreationDate="2015-09-28T02:49:53.873" Score="31" Body="&lt;p&gt;Don't believe everything you see in the movies. Doubly so if the movie originated in Hollywood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The world altitude record for a helicopter is 40,814ft (12440m), some 11,000 feet (3353m) higher then Everest, set in 1972 &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_altitude_record#Rotorcraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reference: Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2005 Didier DelSalle famously touched down on the summit of Everest in an AS350 Squirrel &lt;a href=&quot;https://en.wikipedia.org/wiki/Didier_Delsalle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reference: Wikipedia&lt;/a&gt;. See below for a video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both feats involved specially prepared aircraft and highly experienced crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/WXNXSvnCtKA?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has already been pointed out, a helicopter, just like any other aircraft, has a ceiling above which they cannot fly. Since it's clear that it is possible to fly helicopters to the required altitude &lt;strong&gt;in certain conditions&lt;/strong&gt;, this is just a red herring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real reason helicopters don't routinely fly to those altitudes is that they're not designed to. As with everything in aviation, performance is a trade off between engineering, aerodynamics and commercial pressures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a big market for helicopters that can fly up to, say, 12-15,000ft (3600-4500m). The market for helicopters capable of rescuing climbers from the top of Everest is, at best, limited, and the technical demands of building a craft routinely capable of such a flight will push the costs up dramatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, they don't because nobody will pay for it.&lt;/p&gt;&#xA;" OwnerUserId="11417" LastEditorUserId="45359" LastEditDate="2020-01-06T16:42:14.877" LastActivityDate="2020-01-06T16:42:14.877" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="21305" PostTypeId="1" AcceptedAnswerId="21311" CreationDate="2015-09-28T08:44:37.810" Score="20" ViewCount="19733" Body="&lt;p&gt;In flight, engines provide all the needed energy (bleed air, hydraulic and electrical power). So the APU can be shut down shortly after engines are running. But I imagine that starting the APU in midair is a well known procedure because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I understand that starting the APU while the engines are still running is common given the answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12852/how-are-apus-started&quot;&gt;this question&lt;/a&gt; (even if done when the aircraft has landed)&lt;/li&gt;&#xA;&lt;li&gt;In the US Airways 1549, the APU was started in midair [1]&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How is the APU used in midair? When is it started/shut down while the aircraft is not on the ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If needed, the answers can be restricted to airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1] &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf&quot; rel=&quot;noreferrer&quot;&gt;NTSB report p.19&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2019-10-11T16:08:59.563" Title="In what conditions is the APU used in midair?" Tags="&lt;apu&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21306" PostTypeId="1" AcceptedAnswerId="21320" CreationDate="2015-09-28T08:59:35.240" Score="10" ViewCount="24510" Body="&lt;p&gt;As the APU (Auxiliary Power Unit) can be turned off when the engines are running, a functional APU may not be needed given you are able to start at least one engine. This question is in two parts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it technically feasible to operate an airliner without APU (with the necessary ground support)?&lt;/li&gt;&#xA;&lt;li&gt;If so, in what conditions is it legal (number of passengers transported, &lt;a href=&quot;http://www.skybrary.aero/index.php/Minimum_Equipment_List_%28MEL%29&quot; rel=&quot;noreferrer&quot;&gt;MEL&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_test&quot; rel=&quot;noreferrer&quot;&gt;test flight&lt;/a&gt;,...)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This question focuses on airliners. If needed, it can be narrowed to best-sellers (B737 and A320).&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1696" LastEditDate="2015-09-28T19:13:28.893" LastActivityDate="2015-09-29T03:31:02.747" Title="Can airliners operate without an operating APU?" Tags="&lt;airliner&gt;&lt;engine&gt;&lt;apu&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21307" PostTypeId="1" AcceptedAnswerId="21319" CreationDate="2015-09-28T09:44:51.683" Score="9" ViewCount="2238" Body="&lt;p&gt;I was talking with a friend about what things would happen if you experienced engine problems in cruise. We were wondering the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What things would need to be changed to arrive in the optimal configuration for range?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://search.informit.com.au/documentSummary;dn=352836499760151;res=IELENG&quot;&gt;Here&lt;/a&gt; I found that the speed is reduced to approximately 80% of the normal cruise value, but I can image that more things change, perhaps the altitude?&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-09-28T12:17:38.287" LastActivityDate="2015-09-28T16:14:53.423" Title="What is the one-engine-inoperative maximum range flight configuration?" Tags="&lt;aircraft-performance&gt;&lt;etops&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21309" PostTypeId="2" ParentId="21306" CreationDate="2015-09-28T10:24:13.123" Score="9" Body="&lt;p&gt;Yes it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the APU the airconditioning and electronics also won't work when the engines are shut down, so a &lt;a href=&quot;https://aviation.stackexchange.com/q/9676/609&quot;&gt;ground power unit&lt;/a&gt; is connected to provide the electricity and enough compressed air to run the air-conditioning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting the engines will need a &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_support_equipment#Air_Start_Unit_.28ASU.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;air start unit&lt;/a&gt; to start one of the engines using compressed air provided by hoses. After that the bleed air from the first engine is enough to start the second.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-09-28T19:47:16.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21310" PostTypeId="1" AcceptedAnswerId="21313" CreationDate="2015-09-28T10:45:38.580" Score="4" ViewCount="917" Body="&lt;p&gt;Although &lt;a href=&quot;https://aviation.stackexchange.com/questions/615/what-is-the-security-policy-for-getting-into-a-control-tower/619#619&quot;&gt;the question has been asked for pilots&lt;/a&gt;, how does a civilian get access to a ATC facility? I regularly listen to Live ATC, and I'm incredibly curious as to what the inner-workings of a tower look like. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even at that, is there a live video feed of ATCs? &lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-09-28T11:07:47.877" Title="How does a (non-pilot) arrange a tour of an ATC facility?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-09-29T03:16:36.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="21311" PostTypeId="2" ParentId="21305" CreationDate="2015-09-28T10:48:10.033" Score="40" Body="&lt;p&gt;This answer applies to the AVRO RJ (BAe 146), because this is the aircraft I've flown. Other aircraft may or may not have similar features/issues/restrictions.&lt;/p&gt;&#xA;&lt;h3&gt;Reasons for APU use in mid-air&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;For takeoff&lt;/strong&gt;, the APU bleed-air can be used to supply the cabin air pressure system to reduce load on engines. This leads to a significant reduction in runway length required. This is routinely used on short runways.&lt;/li&gt;&#xA;&lt;li&gt;Similar reason &lt;strong&gt;for the landing&lt;/strong&gt;, where, for the missed approach/go-around phase, a high climb gradient is required. For example in mountainous areas or combined with icing conditions, where use of engine bleed air is limited, the APU bleed air can feed the cabin pressurization.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;During flight&lt;/strong&gt;, when in icing conditions. Similar reason as above. The air-frame anti icing system uses that much bleed-air, there is not much left for cabin pressurization (or the other way round). If the APU bleed-air is used to pressurize the cabin, the (already low) climb gradient is improved.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;During flight&lt;/strong&gt;, in the event of a generator failure. The generator of the APU can replace one failed generator of an engine.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;To save engine life&lt;/strong&gt;. If APU bleed air (- to pressurize cabin) is used for normal takeoff, the peak engine temperatures will be lower during takeoff. This increases engine life as the peak engine temperature is the main factor of engine life. It's significantly cheaper to replace an APU than an engine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In all of the above cases, there are restrictions on the operation of the APU. It may not light-up above 15'000 ft or operation above 25'000 ft is not allowed or not recommended. General operating rules for the APU (common sense when using turbines) recommend to use bleed air only after couple of minutes warm-up after startup. Likewise, on shutdown, it should be left running without load to cool down for a few minutes before switching off. The exact timings differ greatly between APU models.&lt;/p&gt;&#xA;&lt;h3&gt;Procedures&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Before Takeoff,&lt;/strong&gt; If the APU is not used during climb, the APU is normally shut down during taxi checks. If the pilots decide to use the APU during climb, it is started during normal engine start. In this case the APU bleed air is used to feed the cabin pressurization.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;After Takeoff&lt;/strong&gt; depending on the model of the APU (and following airline procedures), the APU usage is limited to a specified time or altitude. Before reaching this limit, the APU has to be shut down. (cabin air changeover to the engine bleed air, cool-off period of the APU, switching off)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;During Flight&lt;/strong&gt; In case of a technical problem or emergency, the Abnormal Checklist will suggest or dictate the use of the APU for the remainder of the flight. For example: A generator problem, the APU generator replace the failed generator. This may impose limits to flight altitude and duration.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Before Landing&lt;/strong&gt; Usually after passing 10'000 feet, the APU is started and before the final checks, the cabin pressurization system is switched to the APU.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9999" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-10-11T16:08:59.563" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21312" PostTypeId="2" ParentId="21305" CreationDate="2015-09-28T10:49:01.273" Score="3" Body="&lt;p&gt;If there is a generator failure in one engine (or an engine problem), the APU can be started to provide electrical power if total demand exceeds the capacity of the remaining engines generators.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-09-28T10:49:01.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21313" PostTypeId="2" ParentId="21310" CreationDate="2015-09-28T11:07:47.877" Score="4" Body="&lt;p&gt;For tours, call the facility and say you're interested in aviation, and would like a tour, same as pilots. Depending on the facility, business hour tours are preferred, though others will let you come any time they have available staffing to escort you around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, there are no video feed of any ATC facilities.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-09-28T11:07:47.877" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21314" PostTypeId="2" ParentId="21305" CreationDate="2015-09-28T11:18:08.247" Score="11" Body="&lt;p&gt;Auxiliary Power Units (APUs) are small gas turbine engines used primarily during aircraft ground operation to provide electric power, air conditioning etc and to start the main engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight, the APUs can be used for the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The APUs can be used to provide backup electric power during in-flight operation, in case the main supply fails (or is unable to meet the demand) &lt;/li&gt;&#xA;&lt;li&gt;They can also be used to reduce load on the main engines when power requirements are high (for e.g. in hot and high conditions).&lt;/li&gt;&#xA;&lt;li&gt;In case of an emergency in flight, they can be used to start the engines (Note: The engines can be started in mid air using either cross bleed air or windmilling)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Another thing is that even if the APU fails, most aircraft can operate without any issue using the Ram Air Turbines (RAT).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-28T11:18:08.247" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21315" PostTypeId="2" ParentId="21306" CreationDate="2015-09-28T12:05:02.037" Score="5" Body="&lt;ul&gt;&#xA;&lt;li&gt;Is it technically feasible ?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Yes. Most aircraft switch off their APUs in flight. Also, APU is not mandatory for ground operations if external (Ground) power unit is available. Engine start can be done with an external unit or (in some cases) battery.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In what conditions is it legal?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That depends on a number of factors. In most airline operations, APU is not mandatory. In ETOPS operations, FAA requires that the APU be present if it is required for the aircraft for complying with ETOPS requirements. Also, APU should have in-flight starting capability, whether it is required for operations or not as long as APU is required by aircraft type certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some extreme (for e.g., hot and high) conditions, the airliners should have a functional and operational APU as required by the regulatory authorities. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-28T12:05:02.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21316" PostTypeId="2" ParentId="21307" CreationDate="2015-09-28T12:44:25.117" Score="6" Body="&lt;p&gt;Your guess is right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://commons.erau.edu/cgi/viewcontent.cgi?article=1007&amp;amp;context=jaaer&quot; rel=&quot;nofollow&quot;&gt;In this article&lt;/a&gt; you can read about engine-out procedures.&#xA;Because you can't maintain a certain altitude without sufficient thrust, losing an engine means you can't maintain the same cruising altitude without all the engines running.&#xA;This is, of course, based on the fact that you're flying around the maximum altitude you can fly with both the engines operative given a certain aircraft weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's worth nothing that when losing an engine on modern twin-engines airliners, usually the APU is started to provide electric power and pneumatic pressure (also, hydraulic pressure via electric pumps that runs on electric power produced by the only remaining engine's generator), but usually APUs can't be started and/or run over a certain altitude (20.000 - 25.000 ft, depending from the aircraft), so descending to lower altitudes is somewhat mandatory.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="9656" LastEditDate="2015-09-28T16:14:53.423" LastActivityDate="2015-09-28T16:14:53.423" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21317" PostTypeId="1" AcceptedAnswerId="21328" CreationDate="2015-09-28T12:50:59.430" Score="7" ViewCount="1341" Body="&lt;p&gt;I'm interested in characterizing the radio signatures of magnetrons that appear to be installed in most large aircraft, some examples appearing on this list:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mpdcomponents.com/pdfs/FAA-PMA.pdf&quot;&gt;http://www.mpdcomponents.com/pdfs/FAA-PMA.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that these magnetrons were the first form of radar, but other technologies have largely supplanted them. However, they still seem to appear in the parts lists of modern Boeing and Airbus jumbo jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is what are these magnetrons used for, and when they are used, how they are used? Do pilots still use these regularly?&lt;/p&gt;&#xA;" OwnerUserId="3373" LastActivityDate="2016-11-11T02:31:54.153" Title="What are magnetrons installed on aircraft used for?" Tags="&lt;radar&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21319" PostTypeId="2" ParentId="21307" CreationDate="2015-09-28T14:07:52.160" Score="10" Body="&lt;p&gt;The optimization problem is unchanged from the all engines operative (AEO) cruise optimization. You should still:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Climb as high as practical (&lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983?s=26%7C0.0403#4983&quot;&gt;colder&lt;/a&gt;, thinner air is better for range)&lt;/li&gt;&#xA;&lt;li&gt;Set the lift coefficient such that drag is minimized for propeller aircraft ($c_{Di} = c_{D0}$). For turbojets, minimize energy per flight time ($c_{Di} = \frac{1}{3}\cdot c_{D0}$). For turbofans, pick a value between those two extremes.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the computation of the theoretical optimum polar point please see &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623?s=1%7C0.1071#3623&quot;&gt;this answer&lt;/a&gt; for a complete derivation including wind, or &lt;a href=&quot;https://aviation.stackexchange.com/questions/12541/why-are-many-jet-aircraft-designed-to-cruise-around-fl350-370/12569#12569&quot;&gt;this answer&lt;/a&gt; for a shorter explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your flight altitude will certainly be lower, because you need to generate more thrust on the remaining engine (requiring higher density), which in turn will result in a lower TAS (true air speed). The CAS (calibrated airspeed) should stay about the same, however. The configuration (flaps, gear) should stay unchanged, only rudder deflection will be added for &lt;a href=&quot;https://aviation.stackexchange.com/questions/5062/how-does-an-engine-failure-affects-the-flight-of-an-airplane/5063#5063&quot;&gt;asymmetric thrust&lt;/a&gt; compensation. The resulting sideslip will increase the zero-lift drag of the airplane a little, so a slightly lower speed than in the AEO case would result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the unlikely case that the required density will result in an altitude below ground level, you will need to slow down and need to set flaps to stay airborne, and now the new optimum with flaps will result in a markedly higher lift coefficient because deploying flaps will increase the zero-lift drag quite a bit. If you have the flaps-down polar, the optimum is easy to find.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-09-28T14:20:09.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21320" PostTypeId="2" ParentId="21306" CreationDate="2015-09-28T14:12:30.813" Score="12" Body="&lt;p&gt;Yes, you can operate without an APU.  If the APU is inoperative you will need to write it up and coordinate with maintenance and dispatch to operate under the stipulations of the MEL.  This may restrict certain kind of operations but if we assume a route completely over land this has no effect other than needed ground services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirements for no-APU is simply a &lt;a href=&quot;https://www.youtube.com/watch?v=XxLPl7v7zgE&quot;&gt;ground start &quot;huffer&quot;&lt;/a&gt; cart at your departure airport.  Ideally you want one at the destination as well but if not available you can possibly coordinate leaving an engine running during the turn.  More generally though, if the destination does not have access to a huffer cart you will get an aircraft swap and the non-APU aircraft will be assigned to a route that does have those ground services available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general process of a non-APU flight is keeping ground power and ground air conditioning hooked up to the airplane for pre-flight activity and boarding.  Once the airplane is closed up the ground crew will coordinate with you to provide air via the ground start cart and you'll start one or both of your engines.  After you have an engine running, you'll disconnect all of the ground equipment and push back.  During the taxi, if you only started one engine earlier you'll perform a crossbleed start to start the other engine.  The takeoff engine bleed and pack configuration may be different for a non-APU takeoff but once you are airborne and set the bleeds and packs for post-takeoff you will be operating exactly the same way you would normally operate and the differences cease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On arrival the only differences are to make sure you keep an engine running at the gate until ground power is hooked up.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest downside to operating without an APU is the lack of decent air conditioning during taxi and ground operations.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Other considerations for operating without an APU are airplane specific.  For example, the EMB-145 has two generators per engine and one on the APU for a total of five generators.  The airplane will revert to &quot;essential&quot; power if less than 3 generators are available which means you will lose certain displays and systems that become unpowered.  This means if you had an engine failure during flight without an APU you will be in essential power and have to land in that condition because you cannot start the APU to get back up to 3 generators operating. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-09-28T14:49:05.670" LastActivityDate="2015-09-28T14:49:05.670" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21321" PostTypeId="1" CreationDate="2015-09-28T14:28:42.863" Score="6" ViewCount="864" Body="&lt;p&gt;The image comes from a 1956 Nestle, a chocolate maker, sticker album. 'Maravillas del Universo', serie 1. Chapter has 3 pages, and is entitled: 'The sound barrier', signed by the woman test pilot: Jacqueline Cochran. It indicates it's a Lippisch L-13, but it's not, Lippisch L-13 was a rearwards swept Delta design, with a thick Vertical Fin that included the pilot's cabin, it was tested as a glider. Final version had to use a Ramjet, fueled by burning coal in a rotating basket. YouTube &lt;a href=&quot;https://youtu.be/MvtxjSrImHw&quot; rel=&quot;nofollow noreferrer&quot;&gt;video link&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CrC8Fm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CrC8Fm.jpg&quot; alt=&quot;Drawing from a 1956 Nestle album&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="14897" LastEditDate="2018-01-12T23:07:48.780" LastActivityDate="2021-01-02T22:49:00.750" Title="If this is not a Lippisch L-13, what is it?" Tags="&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21323" PostTypeId="1" AcceptedAnswerId="21324" CreationDate="2015-09-28T14:52:17.260" Score="4" ViewCount="3059" Body="&lt;p&gt;Context: The landing skills of commercial airline pilots vary widely -- ranging from the ability to routinely make feather-touch landings and taxi and almost imperceptible deceleration on the one hand, to habitually landing with a medium-heavy thud and decelerating abruptly, even under normal flying conditions. One guesses that the landing forces on various parts of the landing gear (and also other parts) would momentarily vary by a factor of three or four, or even greater, on some key parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Please elaborate on the stress tolerances built into various parts of the landing gear of common commercial aircraft, such as the Airbus A320 and Boeing 737?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) What kind of stress testing is done on crucial parts of the landing gear, such as tyres, wheels, axles and hydraulic parts?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) What are the backups and fail-safe measures designed into such landing gear?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="11411" LastEditDate="2015-09-28T15:46:05.557" LastActivityDate="2015-09-29T15:58:39.433" Title="What is the stress tolerance of landing gear of commercial aircraft?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21324" PostTypeId="2" ParentId="21323" CreationDate="2015-09-28T16:21:53.493" Score="7" Body="&lt;p&gt;First off, the thud and deceleration may be more related to the conditions as well as the runway length than pilot skill, but lets discuss some of your questions. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;1) Please elaborate on the stress tolerances built into various parts of the landing gear of common commercial aircraft, such as the Airbus&#xA;  A320 and Boeing 737?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is a complex question to answer simply as airplane gear sees lost of loads and some compromises are made for simplicity of operation. For one the rubber used on the tires is quite thick since some of it does wear away on every landing since the gear is not spinning when the plane touches down (you can &lt;a href=&quot;https://aviation.stackexchange.com/questions/3702/why-are-aircraft-tires-not-pre-spun-prior-to-landing-to-preserve-them&quot;&gt;read more on why not here&lt;/a&gt;) The tradeoff here is weight (you need to haul the tires around with you) but they can be used for many cycles. The vertical load is generally handled by an &lt;a href=&quot;https://en.wikipedia.org/wiki/Oleo_strut&quot; rel=&quot;nofollow noreferrer&quot;&gt;Oleo Strut&lt;/a&gt; these allow for a margin of error but they (or the gear system) can be bottomed out and a &lt;a href=&quot;https://www.youtube.com/watch?v=54OSe17RUhc&quot; rel=&quot;nofollow noreferrer&quot;&gt;hard enough landing can result in a bounce&lt;/a&gt;. The last serious load that gear sees is usually side loads when a crosswind landing is made. These are tough to mitigate and its generally the job of the pilot to reduce these loads they will manifest them selves as tire wear and mechanical wear. Perhaps the coolest solution to this was the B-52's full rotating gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NykHM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NykHM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;https://www.flickr.com/photos/my_public_domain_photos/4522579233&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the more interesting non Oleo designs for GA gear is the rubber disks used on Mooneys. These are said to require less maintenance and are easier to replace but are far less forgiving than Oleo struts.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Fy86K.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fy86K.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.ravenware.com/factand/nofic/mooneytrans.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the vertical force is absorbed by the tire its self when the plane touches down the tire does ballon out a bit. As such it is of vital importance that the tire pressure is within a small margin since low pressure can cause excessive ballooning which would lead to side wear depending on gear design.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;2) What kind of stress testing is done on crucial parts of the landing&#xA;  gear, such as tyres, wheels, axles and hydraulic parts?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These parts are generally made by different manufactures and are designed to comply with the aircrafts specs as set fourth by the builder (Boeing etc). Like everything else on a plane these parts have a cycle life (TO/LD) and are replaced when necessary. Since they are high impact I would assume the life is on the shorter side generally speaking. Here is &lt;a href=&quot;http://www.goodyearaviation.com/resources/tirecare.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;some info from Goodyear&lt;/a&gt; on how to care and maintain tires for aircrafts. Heres some good info on &lt;a href=&quot;http://www.avweb.com/news/savvyaviator/192153-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Oleo struts&lt;/a&gt; as well. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3) What are the backups and fail-safe measures designed into such&#xA;  landing gear?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on the plane, bigger planes generally need to spread the load out over more axles/tires which gives them greater redundancy a plane like a 747 has 2 sets of twin axle main gear on each side of the plane so you could lose an axle and still be ok (relatively speaking)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/faajY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/faajY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;compare this with a 737 and you will see that the main gear is less redundant as its a single axle only system. In this case losing one of two tires would be less catastrophic than losing all the gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K2E1N.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K2E1N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.sunvair.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this all to a smaller GA plane where you generally have a single wheel situation &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4mbNw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4mbNw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.youtube.com/watch?v=y-Z78rVN0VA&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one thing all these planes have in common is that the nose wheel is the most delicate part of the landing gear. Hard landings on the nose wheel can collapse the gear or cause porpoising both of which are bad. This is what happens if the gear does not &lt;a href=&quot;https://www.youtube.com/watch?v=c-Lmfcma0ZI&quot; rel=&quot;nofollow noreferrer&quot;&gt;rotate properly&lt;/a&gt; in other words that nose gear saw complete side loads. Planes have be successfully landed with collapsed nose gear or nose gear that wont come down. Its a sight but generally speaking its not the worst thing to happen.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sensors: The only sensor I know of on the gear (and this is plane dependent) is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9456/how-does-the-squat-switch-work&quot;&gt;squat sensor&lt;/a&gt; which is a simple on off for being on the ground or not. The FDR will record 3-axis acceleration but that will be of the airframe which is behind the Oleo struts so the gear its self may see higher loads. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-29T15:58:39.433" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21325" PostTypeId="1" AcceptedAnswerId="21364" CreationDate="2015-09-28T18:08:43.560" Score="7" ViewCount="736" Body="&lt;p&gt;On Air France flight 447 the captain was on rest break and the a/c was being flown by two first officers. Most other instances I know of on long flights there is a relief crew of both a captain and an FO. How common is it to have two FO's and no captain in the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="19" LastEditDate="2015-10-31T14:23:35.873" LastActivityDate="2017-07-01T00:28:39.740" Title="How often are aircraft flown by two FO's?" Tags="&lt;crew&gt;&lt;af447-accident&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21326" PostTypeId="1" AcceptedAnswerId="21327" CreationDate="2015-09-28T18:14:37.303" Score="7" ViewCount="1036" Body="&lt;p&gt;LAAS (Local Area Augmentation System) is a ground-based GPS augmentation system, intended to be placed at airports to get position accuracy down to around 3m (~10ft) from WAAS's 10m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read that it has been installed at a few airports, but can't track them down; I've also heard, anecdotally, that installation has ceased as WAAS is more than sufficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is LAAS still being installed, and if so, where can one fly a LAAS approach?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-09-28T18:26:25.543" Title="What US airports have approaches with LAAS?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;gnss&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21327" PostTypeId="2" ParentId="21326" CreationDate="2015-09-28T18:26:25.543" Score="7" Body="&lt;p&gt;The Local Area Augmentation System was the FAA term for the Ground Based Augmentation System (GBAS), which is an International Civil Aviation Organization (ICAO) standardized system for local area differential systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has migrated to the ICAO term GBAS, though Several historical FAA documents still retain the LAAS terminology.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/faq/laas/&quot;&gt;FAA GBAS FAQ&lt;/a&gt; page,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Currently, two U.S. locations have obtained operational approval for public GBAS use and support revenue airline traffic. These stations are located at Newark Liberty International Airport (EWR) and Houston George Bush Intercontinental Airport (IAH). &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to FAA, development of GBAS continues and,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA and other States are in the process of validating proposed ICAO GBAS standards to support Category III (CAT-III) precision approach operations. The FAA expects ICAO will approve GAST-D Standards and Recommended Practices in 2015&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA continues to validate the GBAS CAT-III requirements as part of the Next Generation Air Transportation System (commonly known as NextGen). The FAA has currently deferred any Federal acquisition decision on GBAS. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, though GBAS and WAAS are mutually exclusive at present, some future aircraft like A350 are expected to support both GBAS and WAAS.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-28T18:26:25.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21328" PostTypeId="2" ParentId="21317" CreationDate="2015-09-28T18:27:35.603" Score="11" Body="&lt;p&gt;The magnetron is a high-powered vacuum tube, that works as self-excited microwave oscillator. They are used mainly in radar transmitters as either pulsed or cw oscillators at frequencies. In (civil) aircraft, they are mostly used in weather radars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They have relatively simple construction but have been replaced in almost all aircraft due to their disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They can usually work only on a constructively fixed frequency.&lt;/li&gt;&#xA;&lt;li&gt;They have poor reliability.&lt;/li&gt;&#xA;&lt;li&gt;They have high power consumption and have noise issues.&lt;/li&gt;&#xA;&lt;li&gt;They have finite life, considerably lesser than solid state devices.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most of the aircraft operating today use solid state devices in their Radars. It may be still used in some older aircraft and helicopters, but they are becoming increasingly rare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weather radars are regularly used by pilots to detect the weather conditions in front of them. According to Airbus &lt;em&gt;Flight Operations Briefing Notes: Optimum Use of the Weather Radar&lt;/em&gt; The weather radar only detects:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rainfall&lt;/li&gt;&#xA;&lt;li&gt;Wet hail and wet turbulence&lt;/li&gt;&#xA;&lt;li&gt;Ice crystals, dry hail and dry snow. However, these three elements give small reflections compared to water droplets. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It does not detect clouds, fog or clear air turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the aircraft in the list were designed 25+ years ago and have (mostly) switched over to solid state devices. Aircrafts are rarely used after 30 years as maintenance becomes expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However magnetrons are still used in some aircraft due to their simple construction and high power output. For example, the WU-880 Radar Receiver Transmitter Antenna in Honeywell Primus 880 radar used in Falcon 2000EX uses magnetron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Almost all commercial aircraft use convection ovens to heat food (they won't have aluminum foils if they microwave ovens were being used); however, microwave ovens are available for aircraft and are used in some executive aircraft. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-28T18:27:35.603" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21329" PostTypeId="1" AcceptedAnswerId="21334" CreationDate="2015-09-28T18:41:03.343" Score="9" ViewCount="2405" Body="&lt;p&gt;You see a lot of experimental canard GA aircraft, and their performance characteristics seem great. Why don't we see any production canard designs? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For clarification. I'm asking about small airplanes, competitors to the Cessna 172 or Piper Archer in size. I'm also asking about airplanes that you can purchase from a manufacturer, like the above aircraft. An example of a company attempting to eventually make a small canard style production GA aircraft is &lt;a href=&quot;http://www.raptor-aircraft.com&quot; rel=&quot;noreferrer&quot;&gt;Raptor Aircraft&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4509" LastEditorUserId="4509" LastEditDate="2015-09-28T19:58:25.050" LastActivityDate="2015-09-29T02:35:52.877" Title="why are there no production canard GA aircraft?" Tags="&lt;general-aviation&gt;&lt;canard&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21330" PostTypeId="1" AcceptedAnswerId="21353" CreationDate="2015-09-28T18:43:32.693" Score="7" ViewCount="2226" Body="&lt;p&gt;Let's say that there is an aircraft with more than one main wing and each of these wings have elevators. Would it be necessary to have a horizontal stabilizer? The figure below shows an example of what I'm thinking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eRpKe.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eRpKe.png&quot; alt=&quot;Tandem Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9731" LastEditDate="2015-09-28T23:25:05.720" LastActivityDate="2017-08-14T22:46:12.870" Title="Is a horizontal stabilizer necessary on an aircraft with a tandem wing?" Tags="&lt;stability&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21331" PostTypeId="1" AcceptedAnswerId="21333" CreationDate="2015-09-28T19:02:28.727" Score="4" ViewCount="909" Body="&lt;p&gt;How did the &lt;a href=&quot;https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_141&quot; rel=&quot;nofollow noreferrer&quot;&gt;BV 141&lt;/a&gt; fly? It looks like it has very uneven weight distribution and the overall design is asymmetric. I'm surprised that it could even take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RMG9u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RMG9u.jpg&quot; alt=&quot;this is a picture of the BV-141&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11428" LastEditorUserId="62" LastEditDate="2015-09-28T20:10:49.763" LastActivityDate="2015-09-28T20:21:10.923" Title="How airworthy was the BV 141?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21332" PostTypeId="1" AcceptedAnswerId="21336" CreationDate="2015-09-28T19:10:07.710" Score="0" ViewCount="1643" Body="&lt;p&gt;1) What are the materials that international airport runways are made of? If runways consists of several layers, what are they made of, and what is their depth and other specifications?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) What are the surface specifications/properties required of such runways?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) What kind of routine maintenance drills do such runways require?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastActivityDate="2015-09-29T21:32:46.467" Title="What are the specs for runways at international airports?" Tags="&lt;runways&gt;&lt;airport-design&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-09-29T03:34:02.180" ContentLicense="CC BY-SA 3.0" />
  <row Id="21333" PostTypeId="2" ParentId="21331" CreationDate="2015-09-28T20:15:25.783" Score="10" Body="&lt;p&gt;Why would you think the weight was not correctly distributed? If the center of pressure and the center of gravity coincide, there is no problem. Every pilot needs to bring the center of pressure right above or below the center of gravity when flying; this is commonly known as &lt;a href=&quot;https://aviation.stackexchange.com/questions/2025/why-pitch-trim-up-down-roll-left-right-switches-on-yoke-or-control-stick&quot;&gt;trimming&lt;/a&gt; the aircraft. Almost all aircraft have small asymmetries which need to be counteracted by small control surface deflections or trim tab settings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the fuselage of the BV-141 is offset to the left and the cockpit is offset to the right. This keeps the spanwise center of gravity location near the center of the wing, so any resulting rolling moment is small. What remains (maybe due to an unusual high or low loading of the cockpit) can be trimmed away with the ailerons. A yawing moment due to asymmetric thrust can also be corrected by rudder trim, and the engine was placed on the left so the &lt;a href=&quot;https://aviation.stackexchange.com/questions/312/whats-p-factor-and-why-does-it-occur&quot;&gt;p-factor of the propeller&lt;/a&gt; (which creates more yawing moment at low speed) would counteract the yawing moment due to its out-of-center position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The BV-141 was designed as an observer platform with an unrivaled field of vision. By using an offset fuselage, only the left side was obstructed by an engine or tailboom. If you compare the BV-141 with its competitor for the same tender, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_189&quot; rel=&quot;nofollow noreferrer&quot;&gt;Focke-Wulf 189&lt;/a&gt;, the advantage should become obvious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rwkv6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rwkv6.jpg&quot; alt=&quot;Focke-Wulf Fw-189&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Focke-Wulf Fw-189 (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_189#/media/File:Focke_Wulf_Fw189.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the BV-141 was a private entry in this contest and was not selected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar aircraft with an &lt;a href=&quot;https://en.wikipedia.org/wiki/Asymmetrical_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;asymmetrical&lt;/a&gt; mass distribution was the &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Flyer_I.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flyer I&lt;/a&gt; of the Wright Brothers. Here, the right wing was 4 inches wider than the left to create additional lift for the heavy engine which was positioned to the right of the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KO2Fc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KO2Fc.jpg&quot; alt=&quot;Front view of the 1903 Flyer I&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Front view of the 1903 Flyer I (picture &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Airplanes/Wright_Airplane_images/1903_Flyer_I/1903_Flyer_Front.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the offset engine position.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-28T20:21:10.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21334" PostTypeId="2" ParentId="21329" CreationDate="2015-09-28T20:45:49.917" Score="13" Body="&lt;p&gt;Why would you fly with a &lt;a href=&quot;https://aviation.stackexchange.com/questions/15316/canard-control-surfaces-vs-tail-control-surfaces/15334#15334&quot;&gt;deployed spoiler&lt;/a&gt; when you can have a clean aircraft? Sure, there are many canard kit plane designs, but when you look closer at their performance, its is not improved by the location of the elevator. &lt;a href=&quot;https://en.wikipedia.org/wiki/Burt_Rutan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Burt Rutan&lt;/a&gt; would always choose a higher wing loading than required to fulfill the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.23#se14.1.23_149&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR part 23 requirements for low speed&lt;/a&gt;, so his designs could cruise faster. When asked about this, his usual response was &quot;**ck the FAA!&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you look closely, canards will give you:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With natural pitch stability a higher lift coefficient on the forward wing which also needs to have some margin for control surface deflections. Consequently, the big, rear wing is operating at a fraction of its potential when the aircraft stalls.&lt;/li&gt;&#xA;&lt;li&gt;The vorticity from the front wing creates a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=40%7C0.0348#8882&quot;&gt;downwash&lt;/a&gt; at the mid section of the rear wing and an upwash at the outer sections. The strength of these induced speeds varies with speed, so the main wing can produce an elliptic circulation at only one angle of attack. At other angles, its induced drag is higher than what is possible with a conventional configuration.&lt;/li&gt;&#xA;&lt;li&gt;The center of gravity is ahead of the main wing, so the landing gear needs to retract into the fuselage, taking space away from the cockpit. To move the wing center section forward, so it can accommodate the landing gear, the wing needs to be swept (&lt;a href=&quot;https://aviation.stackexchange.com/questions/15349/optimal-wing-sweep-angle-for-passenger-airliner/15362?s=1%7C0.3768#15362&quot;&gt;which creates a host of problems of its own&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;There is no good position to put a vertical surface, so again sweep is used to shift some part of the airframe backwards and combine the vertical with winglets. Those need to point upwards, so they do not hit the ground during take-off and landing when the &lt;a href=&quot;https://aviation.stackexchange.com/questions/19368/why-dont-airliners-have-rudders-on-the-winglets/19409#19409&quot;&gt;better winglet would point downwards&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Canards start to make sense when they are &lt;a href=&quot;https://aviation.stackexchange.com/questions/12657/what-advantages-are-provided-by-an-unstable-canard-configuration-for-fighters/12661#12661&quot;&gt;unstable&lt;/a&gt;, but this is not a good approach for a GA aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-09-28T20:45:49.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21335" PostTypeId="1" AcceptedAnswerId="21349" CreationDate="2015-09-28T20:47:54.007" Score="3" ViewCount="1073" Body="&lt;p&gt;Is the ILS CAT III the most technologically sophisticated navigation / landing  system available for helping commercial pilots land a commercial passenger aircraft in severe and extremely low visibility weather conditions. Does the airport require special compatible equipment for this system to work properly? &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="8247" LastEditDate="2015-09-29T19:06:13.853" LastActivityDate="2020-12-07T07:39:35.117" Title="Is the ILS CAT III system the most complex landing system available?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21336" PostTypeId="2" ParentId="21332" CreationDate="2015-09-29T01:25:25.537" Score="-2" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Runways for international airports are usually man made, which means that they are made up of asphalt or concrete and sometimes are a mixture of both. The depth for the runways are 29cm to 33cm.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Runways are usually around 150ft wide. For an international airport will have a runway around 6,000ft long, but depending on the size of the aircraft that land there a runway will need to be 8,000ft or more.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Runway_Maintenance&quot; rel=&quot;nofollow&quot;&gt;I found this link&lt;/a&gt; which should give you information on runway maintenance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="755" LastEditDate="2015-09-29T21:32:46.467" LastActivityDate="2015-09-29T21:32:46.467" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21339" PostTypeId="1" AcceptedAnswerId="21343" CreationDate="2015-09-29T02:10:33.653" Score="-3" ViewCount="2666" Body="&lt;p&gt;A propeller generates lift, which results in prop-wash for thrust(same as helicopters), but when you look at the N1 fan it looks much different than propeller blades. Do turbofan blades generate lift like propeller blades to generate thrust? And why are the blades curved on a turbofan? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://d2t1xqejof9utc.cloudfront.net/screenshots/pics/7c98783e0932a545be8451ac60f296a7/medium.jpg&quot; alt=&quot;Turbofan curved blades&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="675" LastEditDate="2015-09-29T18:57:04.073" LastActivityDate="2015-09-29T18:57:04.073" Title="How does the shape of the blades on N1 fan on a turbofan generate thrust?" Tags="&lt;turbofan&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21340" PostTypeId="2" ParentId="21329" CreationDate="2015-09-29T02:35:52.877" Score="2" Body="&lt;p&gt;The Piaggio P-180 is a GA aircraft with a canard. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-09-29T02:35:52.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21341" PostTypeId="2" ParentId="21281" CreationDate="2015-09-29T02:44:21.707" Score="5" Body="&lt;p&gt;Every aircraft I have flown had a data plate mounted somewhere in the outside, showing the make, model, serial number, and the year of manufacture. You probably can't see it unless you're 3 feet away, but it's there.&lt;/p&gt;&#xA;&lt;p&gt;The relevant regulation in the US is:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§ 45.11 Marking of products.&lt;/p&gt;&#xA;&lt;p&gt;(a) Aircraft. A manufacturer of aircraft&#xA;covered under § 21.182 of this chapter must mark each aircraft by&#xA;attaching a fireproof identification plate that—&lt;/p&gt;&#xA;&lt;p&gt;(1) Includes the&#xA;information specified in § 45.13 using an approved method of fireproof&#xA;marking;&lt;/p&gt;&#xA;&lt;p&gt;(2) Must be secured in such a manner that it will not likely&#xA;be defaced or removed during normal service, or lost or destroyed in&#xA;an accident; and&lt;/p&gt;&#xA;&lt;p&gt;(3) Except as provided in paragraphs (d) through (h)&#xA;of this section, must be secured to the aircraft fuselage exterior so&#xA;that it is legible to a person on the ground, and must be either&#xA;adjacent to and aft of the rear-most entrance door or on the fuselage&#xA;surface near the tail surfaces.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§ 45.13 Identification data.&lt;/p&gt;&#xA;&lt;p&gt;(a) The identification required by § 45.11 (a) through (c) must&#xA;include the following information:&lt;/p&gt;&#xA;&lt;p&gt;(1) Builder's name.&lt;/p&gt;&#xA;&lt;p&gt;(2) Model designation.&lt;/p&gt;&#xA;&lt;p&gt;(3) Builder's serial number.&lt;/p&gt;&#xA;&lt;p&gt;(4) Type certificate number, if any.&lt;/p&gt;&#xA;&lt;p&gt;(5) Production certificate number, if any.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here's an example from a &lt;a href=&quot;https://en.wikipedia.org/wiki/Stinson_108&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stinson 108&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3bcQ6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3bcQ6.jpg&quot; alt=&quot;Stinson 108 data plate&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-01T20:47:12.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21342" PostTypeId="2" ParentId="21306" CreationDate="2015-09-29T03:31:02.747" Score="5" Body="&lt;p&gt;For non-ETOPS the APU is not required if engine generators operate normally. Here's the excerpt from the 767 MMEL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WnS9p.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WnS9p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the carrier doesn't have a spare APU, it can be removed for repairs and the airplane operated if the MEL requirements are in-place and appropriate weight and balance changes are made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LguS3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LguS3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2341" LastActivityDate="2015-09-29T03:31:02.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21343" PostTypeId="2" ParentId="21339" CreationDate="2015-09-29T04:31:18.647" Score="0" Body="&lt;p&gt;Fan blades, propeller blades, rotor blades and wings are all aerofoils and work in much the same way. Variations in shape are just optimisations for each particular use case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the number of times you have asked this question (at least three here and two on &lt;a href=&quot;http://physics.stackexchange.com&quot;&gt;http://physics.stackexchange.com&lt;/a&gt; ) I thought you would have grasped that by now.&lt;/p&gt;&#xA;" OwnerUserId="11430" LastActivityDate="2015-09-29T04:31:18.647" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21344" PostTypeId="1" AcceptedAnswerId="21345" CreationDate="2015-09-29T05:16:22.283" Score="29" ViewCount="8322" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_AC-130&quot; rel=&quot;noreferrer&quot;&gt;Lockheed AC-130&lt;/a&gt; gunship is a heavily armed ground-attack aircraft variant of the C-130 Hercules transporter. The plane is manufactured by Lockheed and converted by Boeing.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/q5lrL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/q5lrL.jpg&quot; alt=&quot;AC-130 in flight releasing flares&quot;&gt;&lt;/a&gt;&#xA;Why are most of the guns in AC-130 installed on the left-hand side (but not right)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://wall.alphacoders.com/by_sub_category.php?id=210553&quot; rel=&quot;noreferrer&quot;&gt;Picture Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="15311" LastEditDate="2017-12-05T19:15:44.730" LastActivityDate="2017-12-05T19:17:59.940" Title="Why are most weapons in AC-130 on the left-hand side?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;c-130&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21345" PostTypeId="2" ParentId="21344" CreationDate="2015-09-29T05:25:12.383" Score="61" Body="&lt;p&gt;It is not designed to strafe, it is designed to loiter over a target or, to apply suppression fire or support fire for a sustained period of time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It often circles a target area and a counter clockwise orbit (circling to the left) makes sense since the captain sits on the left and can keep the area in view at all times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, the weapons are mounted on the left.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-09-29T05:32:27.943" LastActivityDate="2015-09-29T05:32:27.943" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21346" PostTypeId="2" ParentId="21339" CreationDate="2015-09-29T05:49:35.703" Score="0" Body="&lt;p&gt;Think that lift is just the result of pushing air in some direction: downwards for wings or rotors, rearwards for propellers, or in any suitable direction for compressor stages. Anything that moves air in any proportion or direction creates a force in reaction and tends to be moved in the opposite direction, and it moves unless the force is not sufficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RTw6P.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RTw6P.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing that is often not so easy, because in addition of creating this force, let's name it &lt;em&gt;lift&lt;/em&gt;, the process also creates unwanted effects, collectively named &lt;em&gt;drag&lt;/em&gt;. Drag has numerous negative aspects: it increases fuel consumption and often reduces lift created.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anybody can create a device which generates lift, but the role of the aerospace engineer is to increase lift while decreasing drag, and to take into account the technical feasibility, and the limits of materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design will also try to minimize the fuel quantity required to produce the lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this optimization the shape of the device is carefully selected and adjusted, based on result of previously performed tests, and new ones. This leads to different shapes according to conditions of lift creation: desired amount of lift, energy available for this creation, permitted volume and weight, speed of surrounding air, temperature, etc. This is a reason why a compressor blade is not shaped like a helicopter rotor blade, or B737 vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Curiosity and insistence are good drivers, but they need to be guided by some methodology, else you get exhausted soon. What you may lack is a general &lt;em&gt;overview&lt;/em&gt; of aerodynamics. Asking isolated questions is valid, but not the most efficient way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To understand the all aspects you need to dig into the engineer manuals or at least into good vulgarization books. There are many online for free.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way lift, whatever the name is used (e.g. thrust for an engine and propulsive power for a propeller), is really any force created by moving air, so when you open a door you create unwanted lift and vortex without knowing.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-09-29T07:39:54.130" LastActivityDate="2015-09-29T07:39:54.130" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="21349" PostTypeId="2" ParentId="21335" CreationDate="2015-09-29T08:07:21.207" Score="2" Body="&lt;p&gt;Yes ILS equipment for CATIII is the most sophisticated across ILS systems. As people mentioned in comments there are another types of landing systems, which could be more complex.&#xA;No it is not auto landing system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It self CATIII is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot; rel=&quot;nofollow noreferrer&quot;&gt;category of a landing conditions&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also take a look here &lt;a href=&quot;https://aviation.stackexchange.com/questions/14629/what-is-different-between-a-cat-iiia-cat-iiib-and-cat-iiic-ils-approach&quot;&gt;What is different between a Cat IIIA, Cat IIIB, and Cat IIIC ILS approach?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11262" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-09-29T08:30:42.827" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21350" PostTypeId="1" AcceptedAnswerId="21360" CreationDate="2015-09-29T08:39:07.570" Score="12" ViewCount="3292" Body="&lt;p&gt;I know that the maximum angle of climb is reached at maximum specific excess thrust (S.E.T.) for jet airplanes, or minimum drag or maximum $\frac{L}{D}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true, and if yes, is this valid also for propeller airplanes, or is $\gamma_{max}$ reached at another condition for props?&lt;/p&gt;&#xA;" OwnerUserId="6859" LastEditorUserId="6859" LastEditDate="2018-05-17T08:21:26.440" LastActivityDate="2020-02-10T17:45:06.533" Title="Under what conditions can the maximum angle of climb be achieved for jet and propeller aircraft?" Tags="&lt;aircraft-performance&gt;&lt;climb&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="21352" PostTypeId="1" AcceptedAnswerId="21355" CreationDate="2015-09-29T10:31:10.127" Score="27" ViewCount="18424" Body="&lt;p&gt;The US Military's use of drones has become commonplace, and widely known at this point. Although these vehicles are operated from nearby bases during these attacks, it seems like the latency (time of transmission) would be problematic as far as flying goes. Are these vehicles typically flown 100% by autopilot, where there's very little real-time reaction? &lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="1696" LastEditDate="2015-09-29T19:15:09.667" LastActivityDate="2015-09-30T22:01:35.250" Title="How do drones overcome latency?" Tags="&lt;military&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21353" PostTypeId="2" ParentId="21330" CreationDate="2015-09-29T11:30:37.590" Score="10" Body="&lt;p&gt;Is horizontal stabilizer necessary for tandem wing aircraft? not if the main wings are capable of carrying out the functions of the tailplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reasons for horizontal stabilizer are twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To provide stability for the aircraft, as the wing alone configuration is unstable.&lt;/li&gt;&#xA;&lt;li&gt;To provide pitching moment as the long moment arm enables enough moment to be produced by small changes in the lift (via the elevators).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It provides other benefits too (like damping), but these are the main ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft having tandem wings (i.e. having two wings one behind the another), horizontal stabilizer may or may not be present depending on various factors.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the two wings are able to provide stability and provide pitch moment by differential control of the control surfaces (elevators) on them, the tandem wing has no horizontal stabilizer, like the Scaled Composites Proteus.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2kEc7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2kEc7.jpg&quot; alt=&quot;Proteus&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Scaled_Composites_Proteus_in_flight_1.jpg#/media/File:Scaled_Composites_Proteus_in_flight_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Scaled Composites Proteus in flight 1&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In some cases, the above objectives may not be met with the wings alone and a horizontal tail may be required, like the Scaled Composites Advanced Technology Tactical Transport. Interestingly, the aircraft was flown in two configurations. The initial configuration had a cruciform tail.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/k40Q3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k40Q3.jpg&quot; alt=&quot;ATTT&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image Courtesy of Scaled Composites, LLC&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to DARPA report AD-A227- 498, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Analysis of the flight test results of the &quot;Cruciform Tail&quot; configuration disclosed a significant deficiency in the directional stability and engine-out minimum control speed of the airplane as well as some perceived loading difficulties due to low clearance of the aft cargo door.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a result, the configuration was changed into a twin boom 'bronco' tail and flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gRiKh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gRiKh.jpg&quot; alt=&quot;ATTT&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image Courtesy of Scaled Composites, LLC&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some advantages with the tandem wing configuration, like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For same weight, the tandem wings are more compact (i.e. have less wingspan) as both the wings produce lift (This was one of the reasons given by Burt Rutan). They have less frontal area and less parasite drag.&lt;/li&gt;&#xA;&lt;li&gt;In case of tandem wings, both the wings produce lift, on either side of the center of gravity and produce moments about the c.g. in opposite directions. So, for stability, the c.g. is shifted forwards (for e.g. by having the power-plant forward). As the Angle of attack (aoa) increases, the lift force shift towards the rear and as the center of pressure shifts to the rear of c.g., the tail has to produce higher downward force to produce the required counteracting moment. As higher aoa is used mostly in landings, where more lift is required at lower speeds, this is not ideal. However, in case of tandem wings, at higher aoa, lift force of &lt;em&gt;both&lt;/em&gt; the wings move to the rear, resulting in the rear wing having longer moment arm, and by extension, larger moment. So to compensate, the lift produced by the front wing has to be larger, which produces more lift, not less. For this reason, the front wing is set at a higher incidence (so as to produce higher lift) compared to the rear one.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kGExV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kGExV.jpg&quot; alt=&quot;Tandem wing at high angle of attack&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: nurflugel.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In general, the c.g. of a tandem wing aircraft is towards the main forward wing with the rear wing at a smaller incidence compared to the forward one. This means that the forward wing will have higher wing loading and stall first. However, as the rear wing is still producing lift, the nose drops and the front wing starts to produce lift again, giving the pilot some time to react and control the aircraft, unlike the conventional configuration.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As the wingspan is less, the induced drag is more though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-29T11:30:37.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21354" PostTypeId="1" AcceptedAnswerId="21357" CreationDate="2015-09-29T11:49:10.497" Score="26" ViewCount="7227" Body="&lt;p&gt;Refer the image for counterbalanced single blade (Source &lt;a href=&quot;http://www.aviastar.org/helicopters_eng/bo-103.php&quot; rel=&quot;noreferrer&quot;&gt;http://www.aviastar.org/helicopters_eng/bo-103.php&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ground school, they took us for aircraft inspection at end of our ground school classes. The instructor told us that &quot;counterbalanced single blade engines&quot; are efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have 2 questions here&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Why development under these fields are stopped (Bo-102/103)?&lt;/li&gt;&#xA;&lt;li&gt;How Single blade will be efficient than 2 blades rotor-craft engines?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4aQQf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4aQQf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="19" LastEditDate="2016-11-23T13:02:36.730" LastActivityDate="2017-05-04T14:42:30.283" Title="Is it possible to fly with counterbalanced single blade engines?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;engine&gt;&lt;rotorcraft&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21355" PostTypeId="2" ParentId="21352" CreationDate="2015-09-29T12:05:59.680" Score="26" Body="&lt;p&gt;There are multiple ways to fly and control Unmanned Aerial Vehicles (UAV), or drones, for e.g. the Predator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UOQ3X.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UOQ3X.gif&quot; alt=&quot;Predator System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: science.howstuffworks.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some UAVs (like the Global Hawk) can perform the entire mission (from takeoff to landing) autonomously, negating the need for a pilot.&lt;/li&gt;&#xA;&lt;li&gt;Most of the UAVs, like Predator can perform (i.e. fly in) some simple missions (like reconnaissance) autonomously.&lt;/li&gt;&#xA;&lt;li&gt;In case a geostationary satellite is used for communication with the UAV, the latency is around 300 ms (The electromagnetic waves have to travel ~70000 km). In case of other delays (like equipment etc.) this will not be greater than 500 ms or around half a second. This is not significant in case of slow moving systems like Predator (they are not dog-fighting, after all) and the 'pilot' can effectively control the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The only situation where this is a problem is when the UAV is taking off/landing and in this case, the control is handed over to local LoS operators. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The Predator is reported to have a 'latency' of around two seconds, which causes problems during takeoff/landing. According to the &lt;a href=&quot;http://www.telegraph.co.uk/news/uknews/defence/9552547/The-air-force-men-who-fly-drones-in-Afghanistan-by-remote-control.html&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;telegraph&lt;/em&gt;&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But the two-second delay between a pilot moving a joystick in Nevada and an aircraft responding in Afghanistan is enough to cause a crash during take-off and landing. Crews in Afghanistan control 'launch and recovery’ through direct contact with antennae on the aircraft. Half an hour after take-off, control of the Reaper is handed to a crew in Nevada; half an hour before landing, it returns to the crews on the ground in Kandahar. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the RAF also does things the same way. According to the report on &lt;a href=&quot;http://www.bbc.com/news/uk-england-20039085&quot; rel=&quot;noreferrer&quot;&gt;formation of 'drone' squadron' at RAF Waddington&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although the personnel will be permanently based at RAF Waddington, some will go to Afghanistan to control the take-off and landing of the drones locally.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-29T12:05:59.680" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="21356" PostTypeId="2" ParentId="21352" CreationDate="2015-09-29T12:10:58.057" Score="7" Body="&lt;p&gt;The aerodynamic surfaces of a drone are controlled by computers, not by humans. When a human makes a control input this input is broadcast to the UAV, and the computers on the UAV make the appropriate changes to the flight surfaces to carry that input out. It's not direct control of the drone by humans via radio.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-09-29T12:10:58.057" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21357" PostTypeId="2" ParentId="21354" CreationDate="2015-09-29T13:07:41.760" Score="26" Body="&lt;p&gt;Both Bo-102 and 103 were experimental aircraft, with Bo-102 more of a jig than an actual aircraft. They were used a testbed for various technologies and the single blade rotor is only one of them , with the main thrust being in the development of (hinge-less) rigid rotor and (glass fiber reinforced) composite blades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The single blade rotor offers some advantages over the (normal) multi-blade configurations like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The blade passes through 'clean' air and is thus more efficient compared to the multi-blade configurations, where the (following) blade passes through the turbulent (wake) air from the previous blade, at-least in hover.&lt;/li&gt;&#xA;&lt;li&gt;The single blade propeller is compact and for this reason, is used in some self launching gliders which fold their propellers inside their fuselage,like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Alisport_Silent_2_Targa&quot; rel=&quot;noreferrer&quot;&gt;Alisport Silent 2 Targa&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/e298a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e298a.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are significant problems associated with this design,which makes it (mostly) unsuitable for widespread use.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For reducing vibrations, the blade has to be counterbalanced by a mass, which is practically dead weight. While this may be acceptable for small and lightweight propellers used in gliders, this is a major problem in helicopter blades, which are significantly heavier. For example, the Mi-17 Main Rotor Blade weighs ~140 kg.&lt;/li&gt;&#xA;&lt;li&gt;If the mass is  kept low, the lever arm is huge and this increases drag.&lt;/li&gt;&#xA;&lt;li&gt;Though the blade may be  balanced at the pitch axis (to reduce vibrations), torque induced in the rotor blade (due to lift) will cause significant vibrations. As the torque is increased, if the weight is fixed, the rotor will tend to rotate the engine and rip it off. The only way to prevent this is to balance the blade, both aerodynamically and centrifugally, which is easier said than done.&lt;/li&gt;&#xA;&lt;li&gt;The same problem arises as the drag of the blade is different from that of the mass arm, with a torque being created parallel to the axis of rotation. &lt;/li&gt;&#xA;&lt;li&gt;The rotor blades usually 'cone' in flight; this means that the lift vector is slightly tilted &lt;em&gt;towards&lt;/em&gt; the center, not concentric with the rotor plane.&lt;/li&gt;&#xA;&lt;li&gt;The blade has aerodynamic forces acting on it while the balance weight does not. Due to this, the precess differently, which causes unbalance and vibration. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-30T12:45:45.753" LastActivityDate="2015-09-30T12:45:45.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21358" PostTypeId="2" ParentId="21354" CreationDate="2015-09-29T13:17:07.553" Score="12" Body="&lt;p&gt;The number of blades determine the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13545/why-dont-aeroplanes-use-propellers-with-more-blades-like-the-intake-on-a-fanjet/13549#13549&quot;&gt;solidity ratio&lt;/a&gt; of a propeller. If you need to limit tip speed and propeller diameter, the propeller will have a high solidity ratio by using many, short blades. Take &lt;a href=&quot;https://aviation.stackexchange.com/questions/8907/why-are-there-so-many-different-propeller-shapes/8909#8909&quot;&gt;a ship's propeller&lt;/a&gt;: It needs to work in the space between the draft of the ship and the waterline, so it will have many stubby blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If space allows, a bigger propeller has a &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383?s=6%7C0.0610#15383&quot;&gt;better efficiency&lt;/a&gt; because it  can use a larger mass of air for lift creation. If the propeller has a low &lt;a href=&quot;https://aviation.stackexchange.com/questions/16519/what-is-the-difference-between-types-of-propeller/16521?s=1%7C0.1589#16521&quot;&gt;advance ratio&lt;/a&gt;, the wake of one blade might interfere with the next, so packing more blades will increase the risk of interference. The fewer blades you need for lift (or thrust) creation, the better. Efficiency generally runs inverse to the number of blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A single bladed propeller or rotor needs a counterbalance, which in effect is a dead weight. When the interference between two blades is low enough and the disc loading of the rotor is not too low, a two-bladed rotor will be the better choice. Disc loading is the lift relative to the area of the rotor disc and dictates the chord of the rotor blade(s) once their number is defined. Only when structural limits will make the chord of an ideal two-bladed rotor too short will a single-bladed rotor be attractive.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-05-04T14:42:30.283" LastActivityDate="2017-05-04T14:42:30.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21359" PostTypeId="2" ParentId="21350" CreationDate="2015-09-29T15:23:13.943" Score="10" Body="&lt;p&gt;The maximum angle of climb for all aircraft is achieved when the specific excess thrust available is maximum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$sin \ \gamma_{max} \ = \frac{(T-D)_{max}}{W}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the thrust varies differently with speed in case of propeller and jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8MZPK.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8MZPK.jpg&quot; alt=&quot;Climb Performance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: code7700.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;em&gt;turbojet&lt;/em&gt; aircraft, the thrust is approximately constant with speed. So, $(T-D)_{max}$ (and maximum angle of climb) occurs are $D_{min}$. This velocity is the $V_{min_{T_{R}}}$, the velocity of minimum thrust (drag) required and also the velocity for maximum angle of climb, $V_{\gamma_{max}}$. i.e. for jet aircraft, $V_{min_{T_{R}}}$ = $V_{\gamma_{max}}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of propeller aircraft, the thrust varies with speed. In general, thrust &lt;em&gt;decreases&lt;/em&gt; with speed. As a result, the maximum excess thrust (i.e. the maximum SET) does not occur at the speed of minimum drag, but usually &lt;em&gt;before&lt;/em&gt; it. As a result, for propeller aircraft, $V_{\gamma_{max}}$ &amp;lt; $V_{min_{T_{R}}}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The condition is the same (max. excess thrust), but the speeds are different.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-29T15:23:13.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21360" PostTypeId="2" ParentId="21350" CreationDate="2015-09-29T15:57:36.600" Score="16" Body="&lt;p&gt;What you say is true only for turbojets and aircraft with fixed-pitch propellers. Generally, all optimum points for variable-pitch propeller driven aircraft are at lower speeds than those of jet aircraft. The reason is the variation of thrust with speed: For propellers, thrust is inverse to speed, while it is roughly constant over speed for turbojet aircraft in the subsonic speed range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, the optimum angle of climb condition can be expressed as &lt;span class=&quot;math-container&quot;&gt;$$\frac{\delta \gamma}{\delta c_L} = 0$$&lt;/span&gt;&#xA;If we assume a quadratic polar, constant propeller efficiency over speed (which means a variable-pitch propeller) and an expression for thrust which lets us model an exponential variation of thrust over speed (&lt;span class=&quot;math-container&quot;&gt;$T = T_0·v^{n_v}$&lt;/span&gt;), we can write this condition as &lt;span class=&quot;math-container&quot;&gt;$$\frac{\delta \gamma}{\delta c_L} = -\frac{n_v}{2}·c_L^{-\frac{n_v}{2}-1}·\frac{T_0·(m·g)^{\frac{n_v}{2}-1}}{\left(\frac{\rho}{2}·S_{ref}\right)^{\frac{n_v}{2}}}+\frac{c_{D0}}{c_L^2}-\frac{1}{\pi·AR·\epsilon}$$&lt;/span&gt;&#xA;The general solution is &lt;span class=&quot;math-container&quot;&gt;$$c_{L_{{\gamma_{max}}}} = -\frac{n_v}{4}·\frac{T·\pi·AR·\epsilon}{m·g}+\sqrt{\frac{n_v^2}{16}·\left(\frac{T·\pi·AR·\epsilon}{m·g}\right)^2+c_{D0}·\pi·AR·\epsilon}$$&lt;/span&gt;&#xA;For jets and fixed-pitch propeller aircraft (&lt;span class=&quot;math-container&quot;&gt;$n_v = 0$&lt;/span&gt;) the solution is quite simple, because the thrust terms are proportional to the thrust coefficient &lt;span class=&quot;math-container&quot;&gt;$n_v$&lt;/span&gt; and disappear: &lt;span class=&quot;math-container&quot;&gt;$$c_{L_{{\gamma_{max}}}} = \sqrt{c_{D0}·\pi·AR·\epsilon}$$&lt;/span&gt;&#xA;For turbofan and variable-pitch propeller aircraft, we have less luck and get a much longer formula. This is the one for propellers (&lt;span class=&quot;math-container&quot;&gt;$n_v = -1$&lt;/span&gt;):&#xA;&lt;span class=&quot;math-container&quot;&gt;$$c_{L_{{\gamma_{max}}}} = \frac{T·\pi·AR·\epsilon}{4·m·g}+\sqrt{\left(\frac{T·\pi·AR·\epsilon}{4·m·g}\right)^2+c_{D0}·\pi·AR·\epsilon}$$&lt;/span&gt;&#xA;To arrive from here at a flight speed, I recommend to look up the speed in a polar. Solving this analytically will get messy. Below I have plotted a generic climb speed over air speed chart for different thrust loadings of a typical turbofan. The blue lines show thrust (right Y-axis) and the green lines the resulting climb speed. The two black lines show how the optimum flight speed for best climb speed and best climb angle (steepest climb) vary over thrust loadings. They are easy to find graphically: Pick the tops of the green curves for best climb and the steepest tangent from the origin of the coordinate system to the green lines for best climb angle. Note that they cross when moving from positive to negative climb speeds. With a propeller, the results will look similar, however, the best climb speed line would be vertical. This will collect all optima at the low speed range of the plot - using a turbofan makes the effects easier to see because the optima are spread out more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B2BV1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B2BV1.png&quot; alt=&quot;Climb speeds for different thrust loadings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Climb optima for different thrust loadings (own work)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The optimum climb speed (which is proportional to &lt;span class=&quot;math-container&quot;&gt;$\frac{1}{c_L^2}$&lt;/span&gt;) varies inversely with the square of the thrust loading (&lt;span class=&quot;math-container&quot;&gt;$\frac{T_{ref}}{m·g}$&lt;/span&gt;)² of the aircraft. With lots of excess thrust, the optimum is limited by the stall speed (the black line bends into a vertical trend), while with no excess thrust both optimum speeds &lt;span class=&quot;math-container&quot;&gt;$v_x$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$v_y$&lt;/span&gt; converge. This makes sense: If thrust is just sufficient to keep the airplane from descending at one speed, this speed will both give the best flight path angle and the best vertical speed (unfortunately, both will be 0 at this point). It also helps to reduce induced drag, so aircraft with a high aspect ratio wing will climb steepest at a higher lift coefficient (= lower speed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The steepest climb optimum looks a little more compact if we use the induced drag coefficient directly: &lt;span class=&quot;math-container&quot;&gt;$$c_{L_{\gamma_{max}}} = \frac{2·m·g·(c_{D0}-c_{Di})}{T}$$&lt;/span&gt;&#xA;but since the lift coefficient is hidden again in the induced drag term, and so sits on both sides of the equation, it is much harder to draw conclusions from this version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_L \:\:\:$&lt;/span&gt; lift coefficient&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$n_v \:\:\:$&lt;/span&gt;  thrust exponent, as in &lt;span class=&quot;math-container&quot;&gt;$T \sim v^{n_v} $&lt;/span&gt;&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$T \:\:\:\:$&lt;/span&gt;  thrust&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$m \:\:\:\:$&lt;/span&gt;  mass&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$g \:\:\:\:\:$&lt;/span&gt;  gravitational acceleration&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$\pi \:\:\:\:\:$&lt;/span&gt;  3.14159&lt;span class=&quot;math-container&quot;&gt;$\dots$&lt;/span&gt;&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$AR \:\:$&lt;/span&gt;  aspect ratio of the wing&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$\epsilon \:\:\:\:\:$&lt;/span&gt;  the wing's Oswald factor&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_{D0} \:$&lt;/span&gt;  zero-lift drag coefficient&lt;br&gt;&#xA;    &lt;span class=&quot;math-container&quot;&gt;$c_{Di} \:\:$&lt;/span&gt;  induced drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-02-10T17:45:06.533" LastActivityDate="2020-02-10T17:45:06.533" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21361" PostTypeId="2" ParentId="21352" CreationDate="2015-09-29T18:45:56.953" Score="2" Body="&lt;p&gt;Source: Acquaintances who worked on avionic software and hardware development&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Latency matters for anything mechanical that flies !&lt;/li&gt;&#xA;&lt;li&gt;On-board equipments are developed to handle sub-second interactions. Any interaction from ground is assumed to take many 100s of milliseconds to reach the flight (anything that flies). Humans operating the flight are trained to be quick and anticipate rather than react !&lt;/li&gt;&#xA;&lt;li&gt;To minimize the impact of latency, a series of information keeps flowing thereby converting latency problem into throughput problem. Throughput problems can be handled using multiple beacons / transmitting sources. This does not reduce latency but pre-loads onboard systems with accurate data to anticipate next 500 mS or so.&lt;/li&gt;&#xA;&lt;li&gt;To understand the solutions for latency, look for 2 businesses that are latency sensitive - gaming and high frequency trading. To put things in perspective, in HFT, a market event is detected by software and it generates an order and sends it - all under 1 micro-sec. Further latencies in network stack is not measured here but it gives you a sense of what operates here.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11446" LastActivityDate="2015-09-29T18:45:56.953" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21362" PostTypeId="2" ParentId="19588" CreationDate="2015-09-29T19:08:03.877" Score="0" Body="&lt;p&gt;Multi core systems means at the processor level, there has to be an interconnect bus that shares data. This interconnect brings some level of indeterminism at nano-second levels - what if the data requested is in the cache of core 1 and the process is in core 2? What if contention arises?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when RTOS starts the micro-kernel how will it leverage multiple cores - as separate units? Will it meet stringent safety guidelines if it shares L3 cache but has separate L1 / L2 cache?&lt;/p&gt;&#xA;" OwnerUserId="11446" LastActivityDate="2015-09-29T19:08:03.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21364" PostTypeId="2" ParentId="21325" CreationDate="2015-09-29T19:16:13.870" Score="8" Body="&lt;p&gt;I'd say this is quite common on flights that require at least 3 pilots due to length.  The third pilot is almost assuredly going to be qualified as a first officer and this is the common staffing strategy with the US carriers that I am familiar with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Three pilots (by US flag rules) are going to be required for 8-12 hour flights and you'll find that US carriers often will staff a third pilot even on the shorter US east coast &amp;lt;-&gt; western Europe flights.  But what must the three pilot composition be?  Lets examine &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d788b7bd70a82066d8acc951f38916e0&amp;amp;mc=true&amp;amp;node=se14.3.121_1543&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 121.543&lt;/a&gt; the requirement to relieve a PIC (excepted):   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§121.543   Flight crewmembers at controls.&#xA;  (a) Except as provided in paragraph (b) of this section, each required flight crewmember on flight deck duty must remain at the assigned duty station with seat belt fastened while the aircraft is taking off or landing, and while it is en route.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) A required flight crewmember may leave the assigned duty station—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) If the crewmember is taking a rest period, and relief is provided—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) In the case of the assigned pilot in command during the en route cruise portion of the flight, &lt;strong&gt;by a pilot who holds an airline transport pilot certificate not subject to the limitations in §61.167 of this chapter and an appropriate type rating, is currently qualified as pilot in command or second in command, and is qualified as pilot in command of that aircraft during the en route cruise portion of the flight&lt;/strong&gt;. A second in command qualified to act as a pilot in command en route need not have completed the following pilot in command requirements: The 6-month recurrent flight training required by §121.433(c)(1)(iii); the operating experience required by §121.434; the takeoffs and landings required by §121.439; the line check required by §121.440; and the 6-month proficiency check or simulator training required by §121.441(a)(1);&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The limitations of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d788b7bd70a82066d8acc951f38916e0&amp;amp;mc=true&amp;amp;node=pt14.2.61&amp;amp;rgn=div5#se14.2.61_1167&quot; rel=&quot;noreferrer&quot;&gt;61.167&lt;/a&gt; mentioned above mean those under the age of 23 are not eligible to relieve the PIC. What does it mean to be &quot;qualified as pilot in command of that aircraft during the en route cruise portion of the flight?&quot;  The closest I can find to answer that is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d788b7bd70a82066d8acc951f38916e0&amp;amp;mc=true&amp;amp;node=se14.3.121_1436&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;121.436&lt;/a&gt; which says to be act as a PIC you must have an ATP and be at least 23 years old, have a type rating and have at least 1000 hours combined from part 121 SIC, part 91.1053(a)(2)(i) PIC, part 135.243(a)(1) PIC time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means practically, is that a second in command who &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;holds an ATP, &lt;/li&gt;&#xA;&lt;li&gt;is at least 23 years old,&lt;/li&gt;&#xA;&lt;li&gt;is type rated in the airplane,&lt;/li&gt;&#xA;&lt;li&gt;is qualified as a second in command, and&lt;/li&gt;&#xA;&lt;li&gt;has at least 1000 hours SIC time with any airline&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;may relieve a PIC during en-route flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is further reinforced by the remainder of the quoted portion of 121.543 that says an SIC qualified as PIC need not have any of the required checks a PIC must have (line check, 6 month sim check, etc).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a major airline it is likely that SIC have ATPs and are type rated during initial training and most major new-hires will be older than 23.  It is also likely they have prior airline experience to give them 1000 hours SIC.  Even if they don't have that experience, they'll have it in a 18 months or less after being hired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that pretty much any FO at the airline and surely any FO who has been there for a year or two is going to be qualified to relieve a PIC.  Because an FO can relieve the PIC and can also relieve an SIC, the third pilot need only be an FO.  This means our crew of three will be one captain and two first officers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the economics involved and the behavior of US airlines when it comes to costs, they will staff an FO wherever they can versus staffing a captain.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To bring this full circle, back to our 8-12 hour flights to/from the US by US carriers that require 3 pilots they will almost always be flown by two first officers during the en-route portion of the flight.   &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'm not familiar with non-US regs, so this might not apply.  Given that air carrier rules by the FAA are compatible with ICAO though, I'd guess that this is the common case in other jurisdictions as well.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-09-29T19:16:13.870" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21366" PostTypeId="1" CreationDate="2015-09-29T20:13:59.340" Score="16" ViewCount="3447" Body="&lt;p&gt;On the F-14 as you can see from a picture there is some exhaust like thing in between engines. What is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WA4c2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WA4c2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11451" LastEditorUserId="3386" LastEditDate="2018-07-27T08:09:41.143" LastActivityDate="2021-02-02T04:54:11.550" Title="What is this thing between the engines on the F-14 Tomcat?" Tags="&lt;feature-identification&gt;&lt;f-14&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21367" PostTypeId="2" ParentId="21366" CreationDate="2015-09-29T20:23:00.073" Score="19" Body="&lt;p&gt;This is the line for &lt;a href=&quot;https://books.google.de/books?id=J-8cAgAAQBAJ&amp;amp;pg=SA1-PA52&amp;amp;lpg=SA1-PA52&amp;amp;dq=F-14%20fuel%20dump%20line&amp;amp;source=bl&amp;amp;ots=7WP8SFkTeO&amp;amp;sig=6uCoMgffd4mbTfbfbbDTFZXXTqg&amp;amp;hl=de&amp;amp;sa=X&amp;amp;ved=0CCEQ6AEwAGoVChMIyfbN-ImdyAIVRMUUCh3Zhwj5#v=onepage&amp;amp;q=F-14%20fuel%20dump%20line&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;dumping fuel&lt;/a&gt; in an emergency. If the F-14 needs to land quickly but is too heavy for landing, fuel can be pumped overboard through this pipe. To the left of it is an antenna, and the rod below the fuselage is the arrestor hook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/9116/why-does-the-f-111-sometimes-squirt-a-giant-fire-plume-behind-it-not-afterburn?s=1%7C1.8557&quot;&gt;Australian F-111s&lt;/a&gt; use the same arrangement to great effect during flight displays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the F-14 &lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/101-200/awa169-tomcat/00.shtm&quot; rel=&quot;noreferrer&quot;&gt;Walk-Around Photo Index Page&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YDHJQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YDHJQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Back end of the &quot;beaver tail&quot;.  The red hole is the fuel dump point.&#xA;  The beige item is the rear ALQ-126 antenna, paired to the ones on the&#xA;  wing glove area.  This antenna, like the forward ones, was introduced&#xA;  with block 110 F-14As and all subsequent aircraft.  Also visible is&#xA;  the hook portion of the arresting hook.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-09-29T20:29:04.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21368" PostTypeId="1" CreationDate="2015-09-29T20:56:44.830" Score="7" ViewCount="243" Body="&lt;p&gt;I am just about to (&lt;em&gt;hopefully&lt;/em&gt;) embark on a short internship at the maintenance department of a medium-sized european airline (i.e. under EASA framework). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the internship has been pushed towards being practical, one thing that bothers me is that I am absolutely clueless what I could be allowed to do (and I'd like to know so I could negotiate to get the most of the time with the carrier).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For instance:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Would I be allowed to handle anything flight-wise with supervision? Could I be allowed to interact with the aircraft or only watch and observe?&lt;/li&gt;&#xA;&lt;li&gt;Would I be allowed to even loosen a bolt on a wheel, or do you legally need maintenance certification for that? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2015-09-29T21:06:27.193" LastActivityDate="2019-01-16T10:50:03.947" Title="What can I be allowed to do as a engineering/ maintenance intern at a european airline?" Tags="&lt;easa-regulations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21370" PostTypeId="1" CreationDate="2015-09-29T22:27:14.330" Score="7" ViewCount="1067" Body="&lt;p&gt;Here is a picture of a B-52 located at the Pima air and space museum.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/lvlam.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lvlam.jpg&quot; alt=&quot;B-52&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source:(&lt;a href=&quot;http://www.airplaneexhibits.com&quot; rel=&quot;noreferrer&quot;&gt;www.airplaneexhibits.com&lt;/a&gt;)&lt;/sup&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see in the picture on the right wing next to one of the engines there is some kind of missile carrier, but the left wing has no missile carrier. Wouldn't the weight of the aircraft be very unbalanced with a missile on the right side, but no missile on the left side. I have noticed this in a lot of pictures of B-52's where they are carrying a missile on the right wing, but no missile on the left one.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="39" LastEditDate="2015-09-30T15:42:14.373" LastActivityDate="2016-03-08T13:04:49.473" Title="Why does this B-52 carry a payload only on its right wing?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21371" PostTypeId="1" AcceptedAnswerId="21372" CreationDate="2015-09-29T22:47:27.590" Score="-6" ViewCount="271" Body="&lt;p&gt;Source:(en.wikipedia.org)&lt;a href=&quot;https://i.stack.imgur.com/zcIlB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zcIlB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;They look like fighter jets attached to both wings, but can't really tell what they are. What are these objects on the wings?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-09-29T23:50:49.037" Title="What is this B-52 carrying?" Tags="&lt;missiles&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21372" PostTypeId="2" ParentId="21371" CreationDate="2015-09-29T22:57:37.443" Score="4" Body="&lt;p&gt;They are &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_D-21&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed D-21&lt;/a&gt; drones, an an American Mach 3+ reconnaissance drone. Here is a close photo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/H8GEX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H8GEX.jpg&quot; alt=&quot;D-21 Drone&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:B-52_with_D-21.jpg#/media/File:B-52_with_D-21.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-52 with D-21&lt;/a&gt;&quot; by US Air Force - &lt;a href=&quot;http://roadrunnersinternationale.com/d-21/D-21_historial.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://roadrunnersinternationale.com/d-21/D-21_historial.html&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The D-21s were initially launched from &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_A-12&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed A-12&lt;/a&gt;, the predecessor of SR-71, but were switched over to B-52 after a fatal accident. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-29T23:50:49.037" LastActivityDate="2015-09-29T23:50:49.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21373" PostTypeId="2" ParentId="21370" CreationDate="2015-09-29T23:17:13.820" Score="15" Body="&lt;p&gt;@Peter is right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft in question is the &quot;The High and Mighty One&quot; a NB-52A serial number 52-0003, which was used as a launch aircraft for the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot; rel=&quot;noreferrer&quot;&gt;North American X-15&lt;/a&gt;, a hypersonic rocket powered aircraft. The 'missile carrier' (pylon) is used for carrying the X-15.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a view of the carrier itself, just after launching.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oMzSH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oMzSH.jpg&quot; alt=&quot;X- 15 release&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:X-15_launched_bw.jpg#/media/File:X-15_launched_bw.jpg&quot; rel=&quot;noreferrer&quot;&gt;X-15 launched bw&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was used as the X-15 was not designed to takeoff under its own power; it was rather designed to be carried aloft and drop launched from under the wing of a NASA B-52 'mother ship'. As of March 2016, the X-15 holds the official world record for the highest speed ever reached by a manned, powered aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gZdih.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gZdih.jpg&quot; alt=&quot;X-15 mounting&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://www.air-and-space.com&quot; rel=&quot;noreferrer&quot;&gt;air-and-space.com&lt;/a&gt;; Photo courtesy North American Rockwell.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft underwent &lt;a href=&quot;http://air-and-space.com/nb-521.htm&quot; rel=&quot;noreferrer&quot;&gt;significant modifications&lt;/a&gt; for installation of the pylon, including removal of the wing (no. 3) fuel tank, disabling the inboard flaps in the starboard wing and cutting a notch to accommodate the X-15's vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The heaviest weight the aircraft carried on the pylon was ~53,100 lb, for X-15 with external fuel tanks. A number of tests were carried out and it was found that the carrier aircraft were capable of trimming out the unbalance of the B-52/X-15 combination. So this caused few problems in flight in the operational range.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4197" LastEditDate="2016-03-08T13:04:49.473" LastActivityDate="2016-03-08T13:04:49.473" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21375" PostTypeId="1" CreationDate="2015-09-29T23:48:38.050" Score="5" ViewCount="12330" Body="&lt;p&gt;I can never find any information about the height of the landing gear on any airliner(can you put it into feet and inches).And Is the height of the 747-8 landing gear around the same height as the 737 or airbus a320.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-10-01T21:54:56.597" Title="What is the height of the Boeing 747-8 landing gear?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21376" PostTypeId="2" ParentId="21375" CreationDate="2015-09-30T00:15:35.177" Score="3" Body="&lt;p&gt;In general, the landing gear height is defined as the distance between the ground and the conjunction between main gear strut and the aircraft structure (fuselage, wing, nacelles, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The landing gear height of any aircraft varies depending the loading conditions and where you measure it (nose or main landing gear). This info is from the &lt;em&gt;747-8 Airplane Characteristics for Airport Planning&lt;/em&gt; document by Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dQBEg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dQBEg.png&quot; alt=&quot;747 Dimesions&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;747-8 Airplane Characteristics for Airport Planning&lt;/em&gt; by Boeing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here, 'E' gives the height of the (main) landing gear attached to the fuselage.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-30T00:25:20.850" LastActivityDate="2015-09-30T00:25:20.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21377" PostTypeId="1" AcceptedAnswerId="21379" CreationDate="2015-09-30T00:52:46.593" Score="2" ViewCount="4374" Body="&lt;p&gt;I'm new to flying and I have this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose I'm ascending to 2000 ft. at 67 kts and 2450 RPM. When I reach 2000 ft. maybe the plane wants to keep going up, even after I lower the RPM TO 2200, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do I make the plane flight straight and level at 2000 ft? With the trim and keeping 2200 RPM, or lowering the RPM to, for example, 2100?&lt;/p&gt;&#xA;" OwnerUserId="9941" LastActivityDate="2018-10-23T09:23:09.773" Title="How to maintain straight and level flight after a climb?" Tags="&lt;climb&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21378" PostTypeId="1" CreationDate="2015-09-30T00:55:29.743" Score="0" ViewCount="32" Body="&lt;p&gt;There are many weather products available on AviationWeather.gov and many other sites. What do you use for preflight planning? &lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-09-30T00:55:29.743" Title="What weather products do you use to determine whether or not a flight is safe?" Tags="&lt;weather&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-09-30T01:27:48.687" ContentLicense="CC BY-SA 3.0" />
  <row Id="21379" PostTypeId="2" ParentId="21377" CreationDate="2015-09-30T01:26:08.253" Score="2" Body="&lt;p&gt;It all depends...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will be some minimum power required to maintain level flight at any given altitude. If you're applying more power than that then you can trim for level flight at any power setting. More power means faster flight, higher fuel consumption and less range, while less power will save fuel and take longer. It's really your call, but I'm sure your flying school will opt for economy every time!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also find that some light aircraft have prohibited ranges for RPM. Some Robin aircraft, for example, prohibit continuous operation in a band just above 2000rpm (don't remember the exact details) so you'd have to trim at a power setting below or above that band.&lt;/p&gt;&#xA;" OwnerUserId="11455" LastActivityDate="2015-09-30T01:26:08.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21380" PostTypeId="1" AcceptedAnswerId="21385" CreationDate="2015-09-30T01:42:49.110" Score="23" ViewCount="79086" Body="&lt;p&gt;When landing, what exactly do the phrases &quot;approaching minimums&quot; and &quot;minimums&quot; mean in a commercial jet aircraft,  when heard from the onboard cockpit voice.&lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="572" LastEditDate="2015-09-30T07:04:36.527" LastActivityDate="2017-12-16T11:26:55.580" Title="What do the callouts &quot;approaching minimums&quot; and &quot;minimums &quot; mean?" Tags="&lt;landing&gt;&lt;approach&gt;&lt;phraseology&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21381" PostTypeId="2" ParentId="21380" CreationDate="2015-09-30T01:53:23.160" Score="17" Body="&lt;p&gt;&quot;Approaching Minimums&quot; you are about at your minimum descent altitude (MDA) or decision altitude (DA).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Minimums&quot; means you've arrived at that altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots use those phrases to alert the pilot flying when he us getting close to the ground.  At minimums he will either have the runway environment in sight and decide to continue and land on the runway or he will not have the runway environment in sight and decide to go around.  &lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="572" LastEditDate="2015-09-30T09:49:03.127" LastActivityDate="2015-09-30T09:49:03.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21382" PostTypeId="2" ParentId="21377" CreationDate="2015-09-30T01:57:07.913" Score="0" Body="&lt;p&gt;You need to reduce power or lower the nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most likely you will want to travel faster than 67kts so you will need to lower the nose and allow the airplane to accelerate.  As it accelerates, you will need to trim the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Proper trim technique requires you set the pitch and power for phase of flight and hold that with yoke pressure.  You will then trim off that pressure with the trim wheel.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="753" LastEditDate="2018-10-23T09:23:09.773" LastActivityDate="2018-10-23T09:23:09.773" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21383" PostTypeId="1" CreationDate="2015-09-30T02:12:08.860" Score="6" ViewCount="4764" Body="&lt;p&gt;When filing an IFR flight plan, what information might go in the &quot;Remarks&quot; section?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="12720" LastEditDate="2016-01-12T20:28:11.477" LastActivityDate="2017-11-07T17:14:43.477" Title="What information might go in the remarks section of an IFR flight plan?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;" AnswerCount="6" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21384" PostTypeId="2" ParentId="21377" CreationDate="2015-09-30T02:31:35.080" Score="7" Body="&lt;p&gt;Attitude + Power = Performance&#xA;Performance is your airspeed, climb/descend rate, and rate of turn.&#xA;Attitude is pitch, bank, and yaw. &#xA;Power is RPM, if you have fixed pitch prop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do you transition from climb to level flight? When you reach 2000ft, or maybe 1950, push forward on the yoke or control stick to about level pitch, check the altimeter to make sure you're at 2000ft, not climbing or descending.  Your airspeed will start going up. Maintain forward pressure, it is going to increase as the speed increases (you can put some trim in to help).  Once you reach the desired airspeed, reduce throttle to keep the airspeed constant.  Then use trim to take out the pressure on the yoke.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now this will give you a workout, because if you don't know exact RPM that you need to maintain desired speed, you will be chasing it and working the yoke to keep constant altitude.  So I would lower the nose after the climb, let it accelerate, then lower RPM to 2200 and keep the plane in level flight with the yoke and trim.  After a few minutes when everything is stabilized, I would note the airspeed.  Then I would reduce RPM to 2100, retrim nose up to keep level, wait a few more minutes and note the airspeed for 2100 RPM.  And so forth.  You can build a table of RPM and airspeed.  Then, next time you fly, you will just set the correct RPM for desired airspeed.&lt;/p&gt;&#xA;" OwnerUserId="11456" LastActivityDate="2015-09-30T02:31:35.080" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21385" PostTypeId="2" ParentId="21380" CreationDate="2015-09-30T02:56:21.030" Score="27" Body="&lt;p&gt;The &quot;Approaching Minimums&quot; callout is made by the Pilot Monitoring (or, in some cases equipment, the GPWS -- Ground Proximity Warning System) as the aircraft is descending on an instrument approach and has reached an altitude 100 feet above the minimums for that approach -- the Decision Altitude (DA -- typically used for a Cat I ILS, and set as XXX' MSL) or Decision Height (DH -- typically used for a Cat II or Cat III ILS and set as XXX' or XX' on the Radio Altimeter) or Minimum Descent Altitude (MDA -- typically used for a nonprecision approach and set as XXX' MSL).  The response by the Pilot Flying is usually standardized and indicates he is looking outside in order to acquire the visual references he'll need to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;Minimums&quot; callout is made at the minimum altitude, and this is the point that the Pilot Flying has to make a decision -- continue or go around.  His response at this point is again standardized so that the other pilot is entirely clear on the course of action.  His response is usually something like &quot;Landing&quot; or &quot;Continue&quot;, or else &quot;Go Around.&quot;  Often, the autopilot comes off at this point as well &amp;amp; you hear the horn indicating such on the CVR as well.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="524" LastEditDate="2015-09-30T08:57:30.637" LastActivityDate="2015-09-30T08:57:30.637" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21386" PostTypeId="2" ParentId="21352" CreationDate="2015-09-30T03:10:53.297" Score="0" Body="&lt;p&gt;A significant number of these devices use &quot;top/level&quot; control. The operator may have a camera to see what is in front of the device but the main screen they are looking at is a top view of the landscape (including height map) of where it is flying. The altitude is set to &lt;em&gt;x&lt;/em&gt; meters/yards above ground/sea level. The device maintains height and direction based on this input. As the drone isn't in live action and dodging anything - the delays and adjustments do not impact the route of the machine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g. A 90 degree turn only requires 2 signals. One to initiate the turn and the other back to base to confirm the turn is complete and the drone's current positioning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would rarely find a full scale drone needing manual adjustment of anything less than 500 meters. Also the video footage from the drone is usually only uploaded at full quality once it has returned home.&lt;/p&gt;&#xA;" OwnerUserId="11457" LastEditorUserId="11457" LastEditDate="2015-09-30T22:01:35.250" LastActivityDate="2015-09-30T22:01:35.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21387" PostTypeId="2" ParentId="21383" CreationDate="2015-09-30T03:26:54.430" Score="5" Body="&lt;p&gt;No SID/STAR if flying a small airplane and can't make the required climb gradients.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-09-30T03:26:54.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21388" PostTypeId="2" ParentId="21383" CreationDate="2015-09-30T03:29:13.267" Score="5" Body="&lt;p&gt;Put anything that you believe would be relevant for the controllers to know, but not recorded in other fields.  For example, you are filing from XYZ to XYZ to shoot practice approaches.  You can put that in the remarks, noting airports where you want to practice.  This will help ATC handle your flight.&lt;/p&gt;&#xA;" OwnerUserId="11456" LastActivityDate="2015-09-30T03:29:13.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21390" PostTypeId="1" CreationDate="2015-09-30T06:35:33.940" Score="3" ViewCount="440" Body="&lt;p&gt;I need the most simple lift equation that once solved with Mathcad gives a realistic vertical speed of a plane and implicitly the altitude h(t).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the drag eq. (1) leads to a good solution, a Vh(t) that increases and finally reaches a limit (the maximum horizontal speed) and stays there during the duration of the flight, the lift eq. (2) stabilizes at a Lift(t) - m * g = ct. &gt; 0 and in consequence Vh(t) keeps growing indefinitely because an eq. of the type m * dVv(t)/dt = ct. leads to a solution Vv(t) that rises linearly with time.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt;&#xA;&lt;em&gt;It is quite clear that the vertical speed of a plane, Vh(t), can not grow indefinitely. How can I stabilize it to o constant value. What do I have to add in the lift eq.?&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Drag eq.&lt;/strong&gt;: m * dVh(t)/dt = T - Drag(t) (1),&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag(t) = 0.5 * Cd * r * S * ( Vh(t) + Vw(t) )^2,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Lift eq.&lt;/strong&gt;: m * dVv(t)/dt = Lift(t) - m * g (2),&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift(t) = 0.5 * Cl * r * S * ( Vh(t) + Vw(t) )^2,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Vh(t) = horizontal speed, Vv(t) = vertical speed, both of them have to be determined being unknown functions.&lt;/li&gt;&#xA;&lt;li&gt;known parameters: m = the mass of the plane, r =  air density, S = the wing surface, T = thrust = ct., Cd, Cl are the drag and lift coefficients, g = 9.81 m/s^2, Vw(t) = the wind speed, that is usually a known constant but can have other forms given as functions of time, t. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="19" LastEditDate="2016-11-11T13:18:26.890" LastActivityDate="2016-11-11T13:18:26.890" Title="What is the most simple plane lift equation that gives realistic solutions?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21391" PostTypeId="1" AcceptedAnswerId="21394" CreationDate="2015-09-30T06:50:23.547" Score="15" ViewCount="27754" Body="&lt;p&gt;By flat plate I mean this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kHr6r.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kHr6r.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://physics.stackexchange.com/a/182842/37995&quot;&gt;Physics.SE&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low performance indeed, but how much low? How would:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The angle of attack,&lt;/li&gt;&#xA;&lt;li&gt;The speed range,&lt;/li&gt;&#xA;&lt;li&gt;The turn capability,&lt;/li&gt;&#xA;&lt;li&gt;The fuel consumption,&lt;/li&gt;&#xA;&lt;li&gt;Or other significant characteristic&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;compare to the ones of some reference foil, e.g. a &lt;a href=&quot;http://www.aeronautics.nasa.gov/docs/rpt460/airfoils.htm&quot; rel=&quot;noreferrer&quot;&gt;NACA &lt;code&gt;00xx&lt;/code&gt;&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Link to related benchmarks appreciated.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-10-08T12:29:02.817" LastActivityDate="2018-01-16T04:19:02.940" Title="What is the performance of a flat plate wing?" Tags="&lt;aerodynamics&gt;&lt;fixed-wing&gt;&lt;airfoil&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21392" PostTypeId="2" ParentId="21344" CreationDate="2015-09-30T06:54:51.293" Score="9" Body="&lt;p&gt;Traditionally, the doors most used on an aircraft (including civilian ones) are on the left (captain's) side. Often weapons are mounted in door apertures so that additional holes do not have to be introduced into the fuselage. It follows that there are more, more accessible, pre-existing holes on that side of the fuselage.&lt;/p&gt;&#xA;" OwnerUserId="11460" LastActivityDate="2015-09-30T06:54:51.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21393" PostTypeId="2" ParentId="21383" CreationDate="2015-09-30T07:10:41.443" Score="6" Body="&lt;p&gt;The remarks field, also called &lt;strong&gt;ITEM 18 field&lt;/strong&gt; on ICAO flightplans can take a lot of information that you as the pilot deem necessary for controllers or authorities to know about your IFR flight.&lt;/p&gt;&#xA;&lt;p&gt;The list of possible items in an ICAO flightplan ITEM 18 field is available over at the &lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Plan_Filling#Item_18&quot; rel=&quot;noreferrer&quot;&gt;Skybrary&lt;/a&gt;, but here are a few examples that are commonly used:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(c) “TYP/” followed by type(s) of aircraft, proceeded if necessary by number(s) of aircraft, if “ZZZZ” is inserted in Item 9&lt;/p&gt;&#xA;&lt;p&gt;Example: TYP/2 DE HAVILLAND HERON. Up to 60 characters may be used.&lt;/p&gt;&#xA;&lt;p&gt;(e) “ALTN/” followed by the name of alternate aerodrome(s) or bearing and distance to navaid/navigation point closest to alternate point, if “ZZZZ” is inserted in Item 16. Up to 100 characters may be used.&lt;/p&gt;&#xA;&lt;p&gt;Example: ALTN/MEDIUM AIRPORT&lt;/p&gt;&#xA;&lt;p&gt;(k) “OPR/” followed by name of the operator, if not obvious from the aircraft identification in Item 7.&lt;/p&gt;&#xA;&lt;p&gt;Example: OPR/BIG COMPANY&lt;/p&gt;&#xA;&lt;p&gt;(o) “RMK/” followed by any other, plain language, remarks when required by the appropriate ATS authority or deemed necessary. There is no limit in number of characters to be used.&lt;/p&gt;&#xA;&lt;p&gt;Example:RMK/TRAINING ILS APPROACH AT SMALL AIRPORT&lt;/p&gt;&#xA;&lt;p&gt;RMK/STUDENT SOLO FLIGHT&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-09-30T08:23:07.083" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21394" PostTypeId="2" ParentId="21391" CreationDate="2015-09-30T07:50:20.693" Score="15" Body="&lt;p&gt;I cannot answer all your questions, but maybe point you to some facts to come closer to an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most important is the thickness of your &lt;a href=&quot;https://en.wikipedia.org/wiki/Parallelepiped&quot; rel=&quot;noreferrer&quot;&gt;parallelepiped&lt;/a&gt; - more than a few percent will just increase drag, without benefiting performance. It should be as thin as structurally possible. There are lots of model airplanes using flat plates for lift. The most popular are flying discs like that below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tsvQT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tsvQT.jpg&quot; alt=&quot;Flying disc with witch-on-broom motive being launched&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Parallelepiped&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Lift&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The lift curve slope of a flat plate is the same as that of regular airfoils, complete with stall. They have a zero-lift angle of attack of 0° (obviously) and separated flow on the suction side. The maximum lift coefficient of 0.7 to 0.8 is reached at moderate angles of attack - &lt;a href=&quot;https://aviation.stackexchange.com/questions/14508/calculating-a-finite-wings-lift-from-its-sectional-airfoil-shape/14559#14559&quot;&gt;details depend on the aspect ratio&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nfc8F.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nfc8F.png&quot; alt=&quot;lift curve slope comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your typical four-digit NACA airfoil will have a maximum lift coefficient of 1.2 to 1.6, depending on camber and Reynolds number (picture &lt;a href=&quot;http://www.boundvortex.com/images/flat_plate.png&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Due to the missing nose thrust, the aerodynamic force vector will stand almost perpendicular to the plate's plane. It will be slanted slightly backwards due to friction, but the separated flow on the suction side means that friction will mostly happen on the pressure side. As a rough approximation, the drag coefficient of the flat plate is $$ c_D = c_L \cdot \sin\alpha + \frac{0.43}{log\left(\frac{100}{R}\right)^{2.56}} + 0.3 \cdot\delta\cdot\cos\alpha$$&#xA;with $R$ the relative surface roughness, $\delta$ the relative thickness and $\alpha$ the angle of attack. The first part is caused by the direction of the lift vector, the second part is the friction contribution and will be dwarfed by the pressure part, and the third part is an approximation for the suction along the thick trailing edge. At $\alpha$ = 5° and a lift coefficient of 0.5, the drag coefficient will already be around 0.05.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regular NACA airfoils will have a $c_{D0}$ of 0.004 to 0.01, depending on Reynolds number, and their $c_D$ at stall is normally between 0.02 and 0.025.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Performance&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;From the above it is fair to assume that drag in cruise condition will easily be 4 times higher (induced drag is not affected), and the optimum cruise condition will be at a lower speed due to the higher zero-lift drag. On top, the airplane will need a bigger engine to stay airborne, which will reduce its useful load. Expect fuel consumption to increase in line with the drag increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall speed of an aircraft with a flat plate wing will be approx. 50% higher than with a proper airfoil on the wing, and drag will increase much more at high lift coefficients than usual, which translates into very low sustained turn rates and load factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only the angle of attack range will stay similar. All other parameters will be markedly affected.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-09-30T19:21:40.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21395" PostTypeId="1" AcceptedAnswerId="21410" CreationDate="2015-09-30T09:09:19.507" Score="9" ViewCount="8589" Body="&lt;p&gt;Three letter combinations gives $26^3=17576$ possible codes. Some airports have multiple codes (ARN = STO, for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I’m just going to guess that there are more than 17576 airports in the world. Are we reusing these codes?&lt;/p&gt;&#xA;" OwnerUserId="8159" LastEditorUserId="8000" LastEditDate="2015-09-30T14:33:27.453" LastActivityDate="2015-09-30T14:33:27.453" Title="Will IATA codes run out?" Tags="&lt;iata&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21396" PostTypeId="1" AcceptedAnswerId="21415" CreationDate="2015-09-30T09:19:22.417" Score="34" ViewCount="7137" Body="&lt;p&gt;I was curious to know, are there (or were there) any aircraft that regularly carry spare parts to be used for replacement or repairing the aircraft itself? If so, what are those spare parts?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not talking about built-in redundant systems like a second radio, but rather actual physical spare parts. For example, a car carries a spare tyre.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="62" LastEditDate="2015-09-30T19:44:13.683" LastActivityDate="2017-08-22T19:55:02.083" Title="Do any aircraft carry spare parts for making repairs?" Tags="&lt;commercial-aviation&gt;&lt;aircraft-maintenance&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21397" PostTypeId="1" AcceptedAnswerId="21411" CreationDate="2015-09-30T09:59:02.090" Score="12" ViewCount="5028" Body="&lt;p&gt;In airliners, safety demonstrations are performed when the aircraft is leaving the gate. I understand it cannot be done latter as an aircraft incident including an evacuation may occur at take off roll. But I think it could be done earlier (e.g. in waiting area before boarding). This way, if any passenger has any question (e.g. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2528/why-shouldnt-you-inflate-your-life-vest-until-youre-outside-the-airplane&quot;&gt;this one&lt;/a&gt;), this passenger has plenty of time to ask flight attendants before takeoff. This time may also be used to explain why safety demonstration include all those items (life vest inflated outside the airplane is not the only item that could raise questions). Moreover it could be a good use of waiting time before boarding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: As highlighted by &lt;a href=&quot;https://aviation.stackexchange.com/a/21425/3394&quot;&gt;one answer&lt;/a&gt;, some airliners use video to do this demonstration. In this case, the generic items (i.e. not aircraft specific) of the video could be played on screen in waiting area in addition to the actual briefing.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-10-02T00:21:49.163" Title="Why are safety demonstrations done while taxiing?" Tags="&lt;safety&gt;&lt;airliner&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21399" PostTypeId="1" CreationDate="2015-09-30T10:04:09.720" Score="4" ViewCount="2805" Body="&lt;p&gt;In the past I have had instructors suggest that I use COM1 in the air and COM2 on the ground. The rationale was that most aircraft have the COM1 antenna on the belly making it favorable for air to ground when in the air and COM2 on the roof making it favorable for ground to ground when on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can definitely be helpful to &lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/special/antenna.html&quot; rel=&quot;nofollow&quot;&gt;use the top antenna for ground communications and the belly antenna for air&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I frequently fly a late model PA-32 and I haven't found documentation on which communications antenna is which.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also frequently fly Cessna aircraft which usually have all comms antennas on the roof.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I sometimes fly an SR-22 and my instructor suggested using COM1 on the ground and COM2 in the air. This is reverse from what I thought was usual, but indeed the &lt;a href=&quot;http://servicecenters.cirrusdesign.com/techpubs/pdf/AMM/SR20/pdf/23-10.pdf&quot; rel=&quot;nofollow&quot;&gt;SR-22 AMM&lt;/a&gt; shows that the COM1 antenna is on the roof with COM2 on the belly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there really a rule of thumb here or does it vary so much from one aircraft to another that no rule of thumb is possible to say?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-09-30T11:23:17.307" LastActivityDate="2015-09-30T14:51:45.330" Title="Where are the communications antennas normally located on general aviation aircraft?" Tags="&lt;aircraft-design&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21400" PostTypeId="2" ParentId="21397" CreationDate="2015-09-30T10:08:59.463" Score="42" Body="&lt;p&gt;Many passengers don't reach the gate until seconds before the gate closes for a variety of reasons. They won't get the pre-boarding briefing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxiing is the only time before takeoff where the crew knows for sure that all passengers that will be on the plane are there. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-09-30T10:08:59.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21402" PostTypeId="1" AcceptedAnswerId="21412" CreationDate="2015-09-30T10:25:49.083" Score="15" ViewCount="4062" Body="&lt;p&gt;One thing you're repeatedly told as a student pilot is to fly with the stick (or yoke), not the trimmer. To select a new pitch attitude, fly to it with the stick, wait for the aircraft to settle, and then trim away constant forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the position of the elevator trimmer is roughly the same for the same cruise configuration. It would be a lot easier to mark the trimmer with &quot;level flight at 80&quot;, &quot;gliding descent&quot;, and &quot;best climb&quot; positions, and just move it to those positions (before or after setting the throttle appropriately) directly. The trimmer would be the primary means of setting attitude, with the front-back axis of the stick or yoke for temporary adjustments (e.g to bring the nose up a little in a turn).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why aren't controls designed to be used that way, and why do we fly with the stick?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-09-30T13:03:33.970" Title="Why don't we use elevator trim as the primary flight control?" Tags="&lt;flight-controls&gt;&lt;trim&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21403" PostTypeId="2" ParentId="21397" CreationDate="2015-09-30T10:44:56.210" Score="20" Body="&lt;p&gt;The waiting area is a poor choice of place to give a safety briefing. Passengers are talking amongst themselves, fiddling about with hand luggage, or listening to music on earphones, and may not respond well to being interrupted for the briefing. There are often disturbances (e.g. passengers on other flights passing the gate). As ratchet freak pointed out, not all the passengers will arrive early, and if everything is running to schedule, there shouldn't be a wait between the announced boarding time and the actual boarding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, before boarding (most of) the cabin crew is on the aircraft getting ready for the boarding. They don't have spare time to go to the gate to perform the demonstration, so it would mean having extra staff who just do briefings, with an extra risk of briefing for the wrong aircraft. In addition, it's only possible to point out the overhead panels and emergency exits when you're in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the aircraft immediately before take-off, every passenger is in their seat, with no headphones in (in case of an emergency), and the cabin crew are spread out with nothing else to do. It can be an anxious time for passengers and crew alike. It's not only a suitable free period: the briefing makes an important activity to keep passengers and cabin crew alike busy during this time. Finally, even if passengers don't listen to the briefing, it gives them a minute to picture the exit routes in relation to their actual seat location, and mentally plan for an emergency.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-09-30T16:11:03.440" LastActivityDate="2015-09-30T16:11:03.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21404" PostTypeId="1" AcceptedAnswerId="21407" CreationDate="2015-09-30T10:49:13.133" Score="11" ViewCount="29730" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Note that this is more of a Physics question than an Aviation one.&lt;br&gt;&#xA;  &lt;a href=&quot;https://physics.stackexchange.com/questions/32269/what-will-happen-if-a-plane-trys-to-take-off-whilst-on-a-treadmill&quot;&gt;This topic has been extensively covered on the Physics Stack Exchange site&lt;/a&gt;, and the answers there are recommended reading for anyone curious about the forces and physics involved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you had a giant treadmill that was an infinite plane, had an infinitely adjustable speed, and could tread along any of its dimensions, could an airplane take off from it?&lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2015-10-02T18:47:01.237" Title="Can planes take off from a treadmill?" Tags="&lt;theory&gt;&lt;aircraft-physics&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21405" PostTypeId="2" ParentId="21404" CreationDate="2015-09-30T10:57:57.580" Score="15" Body="&lt;p&gt;Yes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes get their thrust by using the air. The wheels are not powered. The drag from the wheels will limit how fast the treadmill can go before the plane won't be able to take off anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's simpler to understand if you pick a different frame of reference. Assume the treadmill is standing still but the air is moving around it in any direction with any speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice I just described a windy day.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-09-30T10:57:57.580" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21406" PostTypeId="2" ParentId="21395" CreationDate="2015-09-30T11:14:15.247" Score="6" Body="&lt;p&gt;As of June 2015, fewer than 2500 IATA codes have been assigned. Codes can be reassigned over time. According to the Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Air_Transport_Association_airport_code&quot;&gt;IATA codes&lt;/a&gt; there have been several IATA codes that have been reassigned. IATA has a mechanism for assigning these airport codes that's available &lt;a href=&quot;http://www.iata.org/publications/Pages/coding.aspx&quot;&gt;online&lt;/a&gt;. Although your original calculation came to some 17000 possible codes, there's a wide variety of reserved codes, and prefixes, so it's actually less than 17500.&lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-09-30T11:14:15.247" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21407" PostTypeId="2" ParentId="21404" CreationDate="2015-09-30T11:19:58.133" Score="30" Body="&lt;p&gt;Everyone collectively went &quot;Oh god, not this one&quot; because this same question has sparked some intense debates in the past. Aircraft rely on airflow over the airfoil (wings/tail etc) to produce lift - which is independent of the movement of the tires. This means that with enough air going over the wing, the aircraft will fly &lt;em&gt;even if it isn't moving forward at all&lt;/em&gt; relative to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why aircraft on ramps at airports need to be tethered to the ground. This isn't only to prevent them from rolling around, but from taking off should the air flow get fast enough over the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested in an entertaining segment, the MythBusters did a &lt;em&gt;fairly&lt;/em&gt; scientific experiment of this. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/YORCk1BN7QY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; Although it isn't perfect, I think it does a good job of explaining the concepts.&lt;/p&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2015-09-30T11:19:58.133" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21408" PostTypeId="2" ParentId="21404" CreationDate="2015-09-30T11:27:36.237" Score="1" Body="&lt;p&gt;This question is at the best, ambiguous. There can be both yes and no answers based on what is being done with the aircraft and treadmill. The point is that for an airplane to lift off, there should be sufficient &lt;em&gt;airspeed&lt;/em&gt;. If there is no wind, there airspeed is equal to the &lt;em&gt;ground speed&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that there is no wind (into or against the aircraft), there are two possible solutions.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the airplane is stationary relative to the ground, it won't take off (as wind speed is zero).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the airplane moves relative to the ground (with sufficient speed), it will take off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Assume that we have a jet airplane (just for sake of argument) and some one pushes the throttle and it begins to move forward. Now, as the treadmill has an infinitely adjustable speed, we can have three conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the treadmill speed is zero, the airplane will eventually generate sufficient lift and take off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the treadmill speed is adjusted such that the airplane is kept stationary &lt;em&gt;relative to the treadmill&lt;/em&gt;, the airplane will take off (as it is moving with respect to ground, and so has some airspeed).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the treadmill speed is adjusted so that the airplane is kept stationary &lt;em&gt;relative to the ground&lt;/em&gt;, the airplane cannot takeoff, as the ground and air speeds are both zero. Note that in this case, the aircraft speed relative to the treadmill is twice that of the speed at which the treadmill is being operated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If there is a wind, the required ground speed can be adjusted accordingly, but the principle remains the same. For example, if the wind speed is equal to the airspeed required for take off, the airplane will lift off even though it is stationary with respect to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, the important concept here is airspeed. It does not matter if the aircraft is on a treadmill, train track or runway.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-30T11:27:36.237" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21409" PostTypeId="2" ParentId="21402" CreationDate="2015-09-30T11:34:34.963" Score="7" Body="&lt;p&gt;The trim will behave differently with different loads, so you cannot use fixed trim settings on each flight, as each flight will be different from a load factor and center of gravity perspective. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While my trim setting for a solo flight with half full tanks will make me us best climb, the same trim setting with 3 additional passengers and full tanks will produce a different result. (Speaking from a GA/SEP perspective).&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-09-30T11:34:34.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21410" PostTypeId="2" ParentId="21395" CreationDate="2015-09-30T11:46:12.080" Score="15" Body="&lt;p&gt;In short, the people sitting over the nose wheel use the ICAO codes, and the people in the back use the IATA codes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The IATA is the International Airline Transport Association. The ICAO is the  International Civil Aviation Organization. While you are correct, the IATA does not have more than 17500 codes, their primary concern isn't creating codes for every airport including grass strips and private airfields. It is easy to think of IATA codes as being concerned essentially with identifiers that the passengers will need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as ICAO is concerned, they contain a country identifier in their codes. They can even be more than 4 digits, as in the case of RU-2244 (Ukrainka Air Base). The vast majority are 4 digit or 5 digit, with the first 1 or 2 as the country code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This allows ICAO to be available for every airport in the world. It is very common to refer to the IATA codes when flying locally, let's say within the USA, and refer to the ICAO if flying internationally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a database structure of all airports in the world (or at least all known ones). This includes any grass/water/helipad/paved runways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a total of: 46,465 airport/airfields including those that have been closed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://ourairports.com/data/&quot;&gt;http://ourairports.com/data/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2015-09-30T11:46:12.080" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21411" PostTypeId="2" ParentId="21397" CreationDate="2015-09-30T11:52:50.067" Score="16" Body="&lt;p&gt;A very simple answer to this question is that the FAA (and international agencies) require it to be so to ensure that all passengers are available to hear/see the briefing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other more robotic/pilot-like answer to this is because it is on the taxi checklist. Haha :)&lt;/p&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2015-09-30T11:52:50.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21412" PostTypeId="2" ParentId="21402" CreationDate="2015-09-30T11:55:05.847" Score="22" Body="&lt;p&gt;Proper trim control technique involves exerting control pressure to attain the desired attitude then using the trim to alleviate the requirement of holding that pressure. There can be a temptation for pilots to make small adjustments using trim alone. Resist the temptation and use the proper procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We use the proper technique because it's the most precise way to use trim. If adjustments are made with the trim directly we'll end up over-controlling and chasing the correct trim position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trim isn't just a convenience. Especially for pilots flying in instrument conditions, alleviating the load of holding control pressure and ensuring that if the pilot lets go of the controls the airplane maintains its attitude are a matter of safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-2of7.pdf&quot;&gt;Airplane Flying Handbook&lt;/a&gt; explains Trim Control starting on 3-6. It lists the proper technique in greater detail and provides a complete rationale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also the matter of doing things the same way every time. Once we've established the right procedure, we should always use it to enforce the habit. This also benefits the pilot when things get busy. Proficient instrument pilots are experts in using trim effectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Predefined trim positions are impractical because they vary based on weight, CG, airspeed and other factors. These factors change the amount of downforce required on the elevator and therefore the trim position. Situations like &quot;level at 8000&quot; or &quot;gliding descent&quot; won't always result in the same trim position. For other control surfaces there are similar factors. We do have predefined trim positions for takeoff, but loading often makes those undesirable and trimming is required immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During flight training, good trimming technique becomes especially important during instrument training. There's a lot of good information about trim and its importance in the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot;&gt;Instrument Flying Handbook&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-09-30T13:03:33.970" LastActivityDate="2015-09-30T13:03:33.970" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21413" PostTypeId="2" ParentId="21402" CreationDate="2015-09-30T12:05:24.117" Score="8" Body="&lt;p&gt;The main reason for having trim is to modify the forces felt by the pilot to relieve strain, or as you say, 'trim away' the constant forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various reason for not using the trim as the primary control or have fixed trim positions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The forces on the stick and by extension the trim varies with the weight and balance of the aircraft. Though the position of the trim may be roughly same for same configuration, what if the configuration changes? What will happen if the number of passengers or luggage changes? By extension, as the fuel is consumed and the aircraft balance changes, the trim position changes. So you cannot have a fixed trim setting.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The trim position will change depending on whether the wing configuration is different for e.g if the flaps are extended.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The trim setting is affected by speed variations. For example, in trimmed condition, if the speed of aircraft is reduced, the stick will push the pilot's hand forward to lower the aircraft angle of attack. This is opposite of the requirement- we need higher angle of attack to maintain level flight at lower speed. The opposite happens as the aircraft is accelerated. This means that adjustment has to be made to trim,and the pilot will end up making more or less continuous adjustments to the trim.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-30T12:05:24.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21414" PostTypeId="1" AcceptedAnswerId="21484" CreationDate="2015-09-30T13:03:50.930" Score="5" ViewCount="1199" Body="&lt;p&gt;A few weeks ago I did an experiment with a model aircraft that has a motorized propeller. I turned on the propeller and it turned at a constant speed. Then I turned on a desk fan and put it in front of the propeller (see the picture below) and I saw an increase in propeller rpm and an increase in noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this also happen to a propeller when a headwind hits it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jf6QI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jf6QI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3386" LastEditDate="2015-10-01T11:44:56.450" LastActivityDate="2015-10-01T15:44:06.753" Title="Would a headwind result in a faster propeller rpm?" Tags="&lt;propeller&gt;&lt;crosswind&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21415" PostTypeId="2" ParentId="21396" CreationDate="2015-09-30T13:05:08.043" Score="43" Body="&lt;p&gt;South African Airways flights to 'less developed' locations in Africa often carry a mechanic and some spares on board. If there are no suitable repair facilities, supplies or maintenance personnel available at the destination, then their own guy can fix any minor mechanical issues. If there's a major problem then they would have to fly in additional repair supplies and staff (and fly out the stranded passengers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found this out on a flight from Johannesberg to Lilongwe (Malawi). A seat was broken in the passenger cabin and SAA's on-board mechanic was able to fix it after a short delay. The captain explained briefly why he was on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that other airlines or operators who operate in undeveloped areas would do the same. It's a lot cheaper to carry a mechanic and a few spares than it is to have an aircraft, crew and passengers stranded. If anything on the &lt;a href=&quot;https://aviation.stackexchange.com/q/12070/62&quot;&gt;MEL&lt;/a&gt; is broken then an airliner isn't airworthy so even a 'minor' issue can ground it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess that the military might do the same for similar reasons, but I have no idea at all about that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-09-30T13:05:08.043" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21416" PostTypeId="2" ParentId="21399" CreationDate="2015-09-30T13:56:01.883" Score="2" Body="&lt;p&gt;In general, while choosing the antenna locations the following considerations are taken into account:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstruction of the signal by the aircraft (components).&lt;/li&gt;&#xA;&lt;li&gt;Interference &lt;/li&gt;&#xA;&lt;li&gt;Structural issues like vibration and flutter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, if the aircraft being operated from a towered airport is fitted with two radios, it is advisable to have the antenna for COM1 on top of the aircraft and COM2 on the bottom, with a separation of at-least one meter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, usually, the top antenna is used in ground and the bottom antenna is used for air to ground communication as VHF (or UHF, for that matter) is line of sight. Note that it does not matter whether the COM1 antenna is on top or bottom; the top antenna is usually used for on-ground communication (sometimes, this doesn't work, as the tail plane might obstruct the signal). Another reason for using top antenna is that the bottom antenna could be damaged in case of hard landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as the antennae don't suffer from 'shadowing' of the aircraft, it can be located anywhere. A good example is the location of antennae in case of homebuilt aircraft from kits, where the both the antenna could be on top or bottom or even have a single antenna for the same model. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the other extreme, the (avionics) manufacturer may prescribe a particular installation location for the antenna (usually for COM1 on top). Also, in some aircraft, the VHF radios will use both the upper and lower antenna. The signal is switched between the upper and lower antennas with coaxial relays, with the top antenna used while on ground, while the bottom one is used in air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the HF antenna is usually on the vertical tail and GPS antenna on top of the fuselage (for satellite signal reception). The antenna are mounted on the aircraft plane of symmetry or symmetrically to the either side of it (like Cessna 150). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a short answer to your question, in general aviation aircraft, the location of com antenna is immaterial as long as there are no communication issues.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-30T13:56:01.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21419" PostTypeId="2" ParentId="21399" CreationDate="2015-09-30T14:51:45.330" Score="6" Body="&lt;p&gt;Honestly? That AOPA article overstates the issue of airframe shadowing (at least for light GA singles): Both antennas will usually work fine on the ground, and will probably work without any issues in the air as well.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airframe shadowing can cause issues, but if it were as big an issue as people like to make of it there would be no aircraft with single-radio installations (because they would either not be able to talk to people on the ground, or not be able to talk to people in the air).&lt;br&gt;&#xA;There are plenty of aircraft flying around with only one radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're concerned about whether your transmissions are readable pick a nice quiet time of the day and ask the tower for a radio check on Com #1, then repeat the process on Com #2. (Because we're talking about AM radio the results of this test are valid for your aircraft's position and heading when you did the test, and in weather conditions similar to those the test was conducted.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The general rule of thumb is that each radio will be connected to a separate antenna (this is necessary if you want them to work independently). Some avionics shops have a preference of which way they wire things, and I'm sure manufacturers have a standard they use in their shops (either the POH or the maintenance manual for your aircraft &lt;em&gt;MAY&lt;/em&gt; tell you what the manufacturer's standard is; it may also be noted on the FAA Form 337 for the avionics installation if one was filed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen varying combinations of which radio is connected to which antenna (&quot;Single radio - Antenna on top&quot; ; &quot;Single radio - Antenna on bottom&quot; ; &quot;#1 Left Wing, #2 Right Wing&quot; ; &quot;#1 Top-Front, #2 Top-Rear&quot;, &quot;#1 Top/Ground, #2 Bottom/Air&quot; ; &quot;#1 Bottom/Air, #2 Top/Ground&quot;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-09-30T14:51:45.330" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21420" PostTypeId="2" ParentId="21396" CreationDate="2015-09-30T15:03:05.280" Score="21" Body="&lt;p&gt;I've heard what you're describing called a &quot;Fly Away Kit&quot; or FAK.  After some brief googling, it seems the exact contents vary depending on the aircraft, operator, and the manufacturer of the FAK, but most seem to contain tools, spare tires, and other items for simple repairs.  Smaller kits are designed to fit behind a panel in the main cabin, while some larger ones are designed to fit in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;Unit Load Device&lt;/a&gt; in the cargo hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a brief description &lt;a href=&quot;http://www.airliners.net/forum/viewtopic.php?f=5&amp;amp;t=771293&amp;amp;p=11127033&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A fly away kit is a bunch of small spare parts and some tools and&#xA;  fluids to get the plane out of a place you don't have any support for&#xA;  the airplane. We have one on all of our 727's because we operate into&#xA;  remote places that would take forever and a day to get a simple part&#xA;  to us that is a show stopper for the flight, it allows us to swap the&#xA;  part and fly away. Things like spare landing light bulbs, radar&#xA;  altimeters, instruments, gyros, gauges and things like that are&#xA;  generally what I have seen and used from in there. In addition we&#xA;  usually have a spare tire and sometimes a brake assembly somewhere in&#xA;  the belly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Example of kit from &lt;a href=&quot;http://www.airliners.net/photo/Iran-Air/Airbus-A300B4-605R/2211822&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wTQ5h.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wTQ5h.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3337" LastEditorUserId="14897" LastEditDate="2017-08-22T19:55:02.083" LastActivityDate="2017-08-22T19:55:02.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21421" PostTypeId="2" ParentId="21396" CreationDate="2015-09-30T15:29:58.903" Score="27" Body="&lt;p&gt;All of the 747-100/200 freighters I flew in the 1990s had FAKs (Fly Away Kits) aboard. I just checked a couple of the weight &amp;amp; balance data sets I still have from having done weight &amp;amp; balance work for one of them up until 2013, and the weights were 1967 and 1939 lbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft was a nose loader, the FAK was usually along the side of the in the vicinity of the retractable ladder used to get from the main deck to the upper deck. If the aircraft was not a nose loader, the FAK was always up against the main deck forward bulkhead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAKs were constructed of heavy duty plywood and opened from the top. One of the airlines had two BOW configurations for each aircraft, one with its FAK, one without, to expedite weight and balance calculations with or without its FAK.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-09-30T15:40:54.137" LastActivityDate="2015-09-30T15:40:54.137" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21422" PostTypeId="1" CreationDate="2015-09-30T15:41:40.057" Score="15" ViewCount="3891" Body="&lt;p&gt;I'm not even in the realm of knowledge of aircraft so don't chew me out on lack of terminology please.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My objective is to fly myself and a 300-pound motorcycle to destinations to ride from there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I weigh 185 lbs, the motorcycle weighs 300-400 lbs, any secondary seating and other interior furnishings would most likely be removed to reduce weight, and, obviously, all the necessary components would stay. As a side note, the aircraft needs sufficient enough door to get a small motorcycle in. Let's not even talk about how unsafe this might be; this is all hypothetical. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How large, or what class, of an aircraft would be needed for such a task to be completed?&lt;/p&gt;&#xA;" OwnerUserId="11472" LastEditorUserId="22726" LastEditDate="2019-09-22T00:20:15.373" LastActivityDate="2019-09-22T00:20:15.373" Title="What size/engine/payload aircraft would be needed for carrying two passengers and a motorcycle?" Tags="&lt;aircraft-performance&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="21423" PostTypeId="2" ParentId="21422" CreationDate="2015-09-30T16:24:03.080" Score="6" Body="&lt;p&gt;The question is what small light GA aircraft has a payload of &lt;/p&gt;&#xA;&#xA;&lt;p&gt;185 + 400 + 185 (ball park for the second passenger) = 770LBS &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second question is how far you want to fly and thirdly getting the bike into the plane. The list may include&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-32R&quot; rel=&quot;nofollow&quot;&gt;Piper Saratoga&lt;/a&gt; (nice loading doors with the seats removed, rumor has it you can get a &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2002/August/1/Piper-Saratoga-II-TC&quot; rel=&quot;nofollow&quot;&gt;piano through the loading doors of a saratoga&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;nofollow&quot;&gt;Beechcraft Bonanza&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;nofollow&quot;&gt;Cessna Caravan&lt;/a&gt; (with type cert) or &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_206&quot; rel=&quot;nofollow&quot;&gt;Cessna 206&lt;/a&gt; on the smaller side of their offerings &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-34_Seneca&quot; rel=&quot;nofollow&quot;&gt;Piper Seneca&lt;/a&gt; (if you have a twin rating) &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://beechcraft.txtav.com/en/baron-g58&quot; rel=&quot;nofollow&quot;&gt;Beechcraft Barron&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and the list goes on (these are just the common ones). Remember that you can always take a gain in useful load if you sacrifice fuel but this is highly dependent on how far you want to go. Removing the seats will buy you back some useful load but here in the US that will require a new weight and balance to be prepared for you by and A&amp;amp;P. This is a pretty common task but need to be done for the plane to be legal without seats. On top of that since most motorcycle weight is in the engine I would be very cautious when doing your W&amp;amp;B for the flight. I can only assume you will strap the bike in, in which case I would measure engine to CG for calculation purposes. You can also take a bit of a gain by draining the gas from the bike before flying. Since you are presumably going to an airport you will be able to gas it up again (possibly with 110LL...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Continuing on from the above list you get into turbo-prop land, depending on cost that may be doable or not for you. Can you further define your mission to include both distance and budget, that will make a big difference. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-09-30T17:59:00.163" LastActivityDate="2015-09-30T17:59:00.163" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21424" PostTypeId="2" ParentId="21422" CreationDate="2015-09-30T16:30:51.473" Score="8" Body="&lt;p&gt;The question is incomplete without information about the range this aircraft should have. &lt;a href=&quot;http://www.pilatus-aircraft.com&quot; rel=&quot;noreferrer&quot;&gt;Pilatus&lt;/a&gt; in Switzerland is always fond to tell of one of their customers who bought not one, but three &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-12&quot; rel=&quot;noreferrer&quot;&gt;PC-12&lt;/a&gt;s for exactly this purpose, and has one plus a Harley-Davison motorcycle stationed on each continent of interest. The size of a PC-12 allows the installation of a crane, so loading and unloading of the motorcycle are simplified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LeMPD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LeMPD.jpg&quot; alt=&quot;PC-12 side view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PC-12 side view, with open cargo door (picture &lt;a href=&quot;http://iflymat.com/picts/pc12%20side%20view.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, even a PC-12 does not have the intercontinental range to go anywhere, but if you plan to stay within one continent, range is not an issue. Alternatives in this class are the Czech &lt;a href=&quot;https://en.wikipedia.org/wiki/Aero_Ae_270_Ibis&quot; rel=&quot;noreferrer&quot;&gt;Aero 270&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_208_Caravan&quot; rel=&quot;noreferrer&quot;&gt;Cessna 208 Caravan&lt;/a&gt;. All use a PT-6 turboprop engine, and you will need professional maintenance to keep them flying, so using them does not come cheap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more reasonable alternative would be piston-engined, and here the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_206&quot; rel=&quot;noreferrer&quot;&gt;Cessna 206 or 207&lt;/a&gt; (which @Terry already suggested) would be a candidate. However, fitting the bike in will be a challenge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want more internal space and are not afraid of antique taildragger airplanes, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-2&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-2&lt;/a&gt; or the Canadian &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-3_Otter&quot; rel=&quot;noreferrer&quot;&gt;DHC-3 Otter&lt;/a&gt; would also be a good and reasonably priced choice - however, maintaining one (and especially its radial engine) will also burn a hole in your pocket. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fWWhH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fWWhH.jpg&quot; alt=&quot;DHC-3 Otter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DHC-3 in Pensacola (picture &lt;a href=&quot;http://www.flickr.com/photos/37467370@N08/7362744582&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-09-30T16:30:51.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21425" PostTypeId="2" ParentId="21397" CreationDate="2015-09-30T16:33:36.783" Score="3" Body="&lt;p&gt;This simplest answer is a matter of economy. If the airline gave the briefing in the terminal or wherever &lt;em&gt;before&lt;/em&gt; loading the passengers, then the airline would have to allocate resources (personnel, demo gear, logistical planning, and policies) to preform this task. It could be done but the cost (monetary and intrinsic) would be high and the ROI would be little to none.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, they choose to do it while taxiing because it is the most economical time to do so as the flight attendants have little to do (as opposed to during flight where passengers are unpredictable in their needs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, interesting to note is how some flights (Delta at least) have switched to a fully automated system for the safety briefings. Note that this procedure actually saves money by freeing up resources previously committed (as well as potential ad revenue).&lt;/p&gt;&#xA;" OwnerUserId="3699" LastActivityDate="2015-09-30T16:33:36.783" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="21426" PostTypeId="1" CreationDate="2015-09-30T17:21:27.380" Score="32" ViewCount="13845" Body="&lt;p&gt;I was &lt;a href=&quot;http://archive.defensenews.com/article/20130118/DEFREG02/301180020/F-35B-Flights-Suspended-Following-Fueldraulic-Failure&quot;&gt;reading&lt;/a&gt; about how the F-35 is having trouble with the &quot;fueldraulic&quot; system. This made me wonder:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;Why don't aircraft use pneumatic systems instead of hydraulic/fueldraulic systems?&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are several advantages of pneumatic (compressed air) over hydraulic (pressurised liquid) or fueldraulic (pressurised fuel) systems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No need to carry hydraulic liquid. That saves weight and maintenance cost.&lt;/li&gt;&#xA;&lt;li&gt;Half as much piping, as there is no need to return hydraulic liquid to the pump - compressed air can be released after use. That saves more weight.&lt;/li&gt;&#xA;&lt;li&gt;Leaks are less dangerous. There is no danger of running out of hydraulic liquid or of leaking fueldraulic liquid catching fire.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are disadvantages too: less pressure -- which means less power per unit of gas/liquid -- and less precision, as gas is compressible. But I feel like these problems should be solvable in a modern computer-controlled aircraft. So what's the problem?&lt;/p&gt;&#xA;" OwnerUserId="11475" LastEditorUserId="1696" LastEditDate="2015-09-30T18:04:02.120" LastActivityDate="2018-02-17T00:24:15.117" Title="Why do aircraft use hydraulics instead of pneumatics?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;" AnswerCount="7" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21427" PostTypeId="1" CreationDate="2015-09-30T17:59:25.857" Score="13" ViewCount="808" Body="&lt;p&gt;When in aerotow in a glider, I thought the correct way to get the towplane to turn right (say) was to move gently to the left. That would gently nudge the towplane’s tail to the left, which would then point the nose to the right and be a good signal that the glider pilot wants to turn right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA glider flying handbook displays the opposite technique in a diagram:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/T7rWU.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T7rWU.png&quot; alt=&quot;towplane turning instructions for a glider&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don’t understand this. If you move right to ask the towplane to turn right, doesn’t that put the glider on the inside of the turn, and put you in the wrong place to follow the towplane around?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is the correct direction?&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="19" LastEditDate="2016-07-14T08:18:31.300" LastActivityDate="2016-07-18T12:48:09.513" Title="How should a glider pilot signal turns to the towplane?" Tags="&lt;glider&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21428" PostTypeId="2" ParentId="21426" CreationDate="2015-09-30T18:07:32.147" Score="15" Body="&lt;p&gt;One of the first reasons that comes to mind is air volume. Remember that a plane may be sitting on the ground on an 80&amp;nbsp;°F (27&amp;nbsp;°C) day, and take off and climb to 35,000&amp;nbsp;ft where temperatures of -50&amp;nbsp;°F (-46&amp;nbsp;°C) may be present. The air in the system would lose volume as it cooled off and would alter the position of the control surface (let's say flaps) with out any control input. Fluids are less susceptible to this problem. Granted this could be controlled, but it would still require a regulation system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Leaks can also be easier to find in a hydraulic system since you can either&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;see fluid leaking out&lt;/li&gt;&#xA;&lt;li&gt;put additives in that can be illuminated under certain lights&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Pneumatic leaks are often found by rubbing soapy water on a joint and watching for bubbles (at least that's how I find them). Sometimes they can be hard to track if they are in awkward places.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="849" LastEditDate="2015-10-01T15:59:50.957" LastActivityDate="2015-10-01T15:59:50.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21429" PostTypeId="2" ParentId="21426" CreationDate="2015-09-30T18:39:01.803" Score="76" Body="&lt;p&gt;The big disadvantage here is the loss of precision due to the high compressibility of gas compared to liquid. Because gases are highly compressible, they provide a buffer to changes in pressure commanded by the operator to move the piston in the cylinder. That poses two problems; first, it means that the pneumatic cylinder doesn't respond instantly to pressure differentials, because the differential must first overcome the cylinder gasket's static friction. Second, it means that the movement of the cylinder is more easily opposed as long as whatever force opposes the gas pressure can overcome said pressure without causing whatever the pneumatic system is controlling to fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To overcome these shortcomings, most pneumatic systems run at very high pressures, so that the pressure differential between the two halves of the cylinder readily overcomes static friction and any other opposing forces. However, that creates another precision problem; high-pressure pneumatic cylinders are essentially two-state systems; the piston or actuator is typically at one or the other of its extremes of movement, and transitions between them very quickly as gas pressure is applied to one side or other of the cylinder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of these behaviors are desirable for aircraft controls; instructors labor daily to teach their students not to ham-fist the controls, instead using a bit of finesse to get the plane to do what they want in a smooth, controlled fashion. Why then, would you want to undo all that finesse with a control system that can only move the surface to the extremes of its travel?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydraulics, by contrast, allow a much higher degree of finesse. Because liquids don't readily change density, the pressure changes within a hydraulic cylinder require much more force to oppose, but by the same token, as the volume changes the pressure on the side being supplied with fluid decreases rapidly. This allows a hydraulic cylinder to be positioned much more accurately, regardless of any external forces acting on the system. The disadvantage is hauling a fairly heavy liquid up into the air, and having only limited capacity to replace it if any of it leaks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Electrical actuators are a common solution to that disadvantage, especiually in light aircraft. Electrical actuators use an electric motor or servo to provide the mechanical action. These actuators can be controlled with a high degree of precision, and their &quot;supply system&quot; is just an electrical circuit, no heavy and complex hydraulic lines and cylinders. Their disadvantages are a tradeoff between speed of movement and maximum applied force while moving; you can either make an actuator that moves very quickly, or an actuator that will move no matter how much force is opposing the movement, but you really can't do both. They're still useful in light aircraft to control flaps (with a cable system used for the main surfaces), because they allow for precise amounts of extension or retraction, and don't have to instantly respond to input like the primary control surfaces do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is something on the horizon that could make pneumatics feasible for aircraft. Hydraulics systems were recently improved with the development of the electrohydraulic servo valve. This system uses a variable electrical potential (voltage) to move a hydraulic cylinder by a prescribed amount proportional to the voltage applied. Pure electrical servos have been around for decades, but the maximum amount of force available from a servo is insufficient for large airliners, while for smaller aircraft the servo motor's relatively high weight compared to simple cable controls is a disadvantage. The electrohydraulic servovalve concept is used in newer large aircraft to replace pure hydraulic or cable/hydraulic hybrid control systems, because the hydraulic system can now be controlled by an electrical circuit instead of hydraulic lines or tensioned cables coupled to the control column. This allows for &quot;fly-by-wire&quot; aircraft such as most Airbus airliners as well as most fighter jet designs of the last 40 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar concept is under development for pneumatics, allowing the precise placement of an actuator using pressurized gas in response to an electrical voltage. This would provide all the advantages of an electrohydraulic system, with considerably lighter weight and faster response, but still having the disadvantage that a significant opposing force could prevent movement of the actuator especially as it approaches the desired position. Whether that will be an issue in a large aircraft remains to be seen, and the weight savings of losing the hydraulic fluid might not be worth it, but if the tradeoff is acceptable, it would further increase range or payload of the next generation of passenger aircraft, with the added safety/reliability feature of being able to compensate for a slow leak in a pneumatic system by simply adding more air with a compressor pump.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-26T18:53:41.587" LastActivityDate="2015-10-26T18:53:41.587" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21430" PostTypeId="2" ParentId="21404" CreationDate="2015-09-30T18:46:06.027" Score="0" Body="&lt;p&gt;Yes. It does not actually matter much which direction and how fast the treadmill would rotate; the aircraft will take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only requirement for generating lift is to move through the &lt;code&gt;air&lt;/code&gt; sufficiently fast. The speed is created by thrust. And the thrust of the aircraft engine does not depend on the ground speed (&quot;ground&quot; would be the surface of the treadmill for this case). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The treadmill can only affect the ground speed so would have no effect on the engine thrust. Hence it would not have significant effect on the air speed either, unless through the friction forces in the bearings of the wheels. I assume that these forces are small in comparison the power of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only chance, as the aircraft chassis is the designed for the limited ground speed only, the treadmill may prevent take off by rotating in the opposite direction fast enough to cause the chassis to collapse. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2015-10-01T08:43:35.553" LastActivityDate="2015-10-01T08:43:35.553" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21431" PostTypeId="1" CreationDate="2015-09-30T18:53:37.593" Score="1" ViewCount="493" Body="&lt;p&gt;Is it possible to obtain the mass flow through the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tumansky_R-25#Specifications_.28R-25-300.29&quot; rel=&quot;nofollow&quot;&gt;Tumansky R-25&lt;/a&gt; turbojet engine mounted on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21#Specifications_.28MiG-21-93.29&quot; rel=&quot;nofollow&quot;&gt;MiG-21&lt;/a&gt; during its various &lt;em&gt;standard&lt;/em&gt; operating (&lt;strong&gt;cruise&lt;/strong&gt;) Mach numbers?&lt;br&gt;&#xA;Note: &lt;em&gt;standard&lt;/em&gt; as in older planes where there were just 3 positions of the inlet cone - upto Mach 1.5, between 1.5-1.9 and above 1.9.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what should be the cruise condition for this plane, given that it is capable of flying at various Mach numbers and thus speeds?&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorDisplayName="user12485" LastEditDate="2015-12-14T13:46:46.180" LastActivityDate="2019-08-10T06:02:51.310" Title="Is it possible to determine the mass flow rate through the engine of MiG-21 during its various cruise Mach no. operations?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;airframe-and-powerplant&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21432" PostTypeId="2" ParentId="21390" CreationDate="2015-09-30T19:41:09.790" Score="3" Body="&lt;p&gt;First, you need to add the effect of density $\rho$: Air density changes with altitude, and this affects both lift and drag (at least if you model airbreathing engines).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For lift $L$, use $$L = c_L\cdot\rho\cdot\frac{v_h^2+v_v^2}{2}\cdot S$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For drag $D$, you should only simplify the equation as much as possible. Your equation is simpler still and doesn't model the increase in drag with more lift. The simplest practical equation will look like this: $$D = \left(c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}\right)\cdot\rho\cdot\frac{v_h^2+v_v^2}{2}\cdot S$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More lift will need more thrust and will limit the upward acceleration. Climbing higher will reduce thrust in proportion with density and limit the possible speed range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient (normally between 0 and 1.5)&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing (ratio of span to mean chord)&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor (use 0.8 when in doubt)&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient (use 0.02 when in doubt)&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-09-30T19:41:09.790" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21433" PostTypeId="2" ParentId="8344" CreationDate="2015-09-30T20:10:24.027" Score="3" Body="&lt;p&gt;It would not be impossible for a Su-25 &quot;Frogfoot&quot; carrying AA-8s to down an airliner, but it's very unlikely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off, let's get something out of the way; neither the R-95Sh engines on early variants, not the improved R-195 on the Su-25T variant, has an afterburner. The Su-25's primary mission profile requires it to fly low and slow over the battlefield to acquire and engage ground targets (it's the Russian answer to the A-10), and its low amount of wing sweep prohibits supersonic flight, so an afterburner is not only completely unnecessary, it's downright dangerous to try to use in a design like this. So, the idea that a Su-25 used afterburners to exceed its service ceiling is pure bunk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Su-25, flying at its mission ceiling of 16,000 feet (which would require the pilot to be on oxygen, which would be available), targeting a 777 at 33,000 feet, would be about 3.5 miles away, vertically, from the airliner. That's well within the range of the R-60 Molniya/Vympel, aka the AA-8 Aphid. However, it would require the pilot to point the aircraft directly upward at the airliner, which would very likely cause the Su-25 to stall before the pilot could get a good lock-on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum targeting range of the AA-8 is believed to be 5 miles; it can fly 6 miles after launch, but keep in mind the missile has to get to where the target aircraft &lt;em&gt;was&lt;/em&gt; when launched, then cover the additional distance the aircraft has covered in that time (the missile would also have to climb 3 miles against gravity and would get none of that energy back &quot;falling&quot; toward the target as many air-to-air missiles do). Given the 3.2 mile vertical separation, the minimum angle the Su-25 pilot would be required to maintain assuming a &quot;boresight&quot; lock-on is required (the aircraft's nose has to point right at the target) is $\sin^{-1} \dfrac{3.2}{5} = 40^o$, and so the 777 could be no further in any horizontal direction from the Su-25 than $\cos (40) * 5 = 3.8$ miles. Some sources claim the R-60 can lock on at up to 45 degrees off-boresight, which would mean the Su-25, if it got a clean &quot;uncaged&quot; IR lock on the 777, could fire from level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in theory, a Su-25, at its service ceiling and closer than 3 miles horizontally from MH-17, could have shot it down. However, there are no reports from civilian or military sources that an Su-25 was anywhere near that close to MH-17, and make no mistake, a Su-25 flying at 16,000 feet would be highly visible on any radar system for a hundred miles in any direction; the Frogfoot has exactly zero radar stealth features.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The German/American intelligence reports on the incident, stating that Russian-allied rebels in the Donetsk Oblast area used an SA-11 Gadfly launcher to bring it down, are more consistent with reality. This self-propelled SAM system is perfectly capable of reaching 33,000 feet (its vertical range is over 80,000 feet; it was designed with the CIA's U-2 Dragon Lady in mind) and can target an aircraft up to 20 miles away at that altitude. In addition, a Ukranian An-26 operating in the area was shot down by a similar launcher, according to the same rebel militia's own statements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why anyone would have targeted the civilian airliner is not known. There are several theories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The separatists may have mistaken MH17 for another Ukrainian transport plane; a UAF An-26 light transport was shot down in the same area by an SA-11 just three days prior to MH17.&lt;/li&gt;&#xA;&lt;li&gt;The Ukrainians might have fired on the plane, believing it to be &quot;Board One&quot;, Putin's personal VIP transport which would have been on its way back from Brazil around that time, and which has reportedly used routes overflying Ukraine before. The Russians state the president's Il-96 was nowhere near Ukraine at the time and there were no plans to overfly the airspace during the trip to Brazil. At any rate, the Ukranians of course deny targeting any civil transport, Russian or otherwise.&lt;/li&gt;&#xA;&lt;li&gt;The separatists may have believed it to be the same plane and fired on it, thinking that an assassination, pinned on the Ukrainians, would spark a full-scale Russian invasion of Ukraine thus accomplishing their goals.&lt;/li&gt;&#xA;&lt;li&gt;The separatists may have intended to implicate Ukraine in the downing of a civilian airliner, weakening international support of the Ukrainian government.&lt;/li&gt;&#xA;&lt;li&gt;The separatists may have deliberately targeted the civilian airliner as a message to keep civilian air traffic away from Ukraine. If they're in possession of more SAMs (highly likely; even the one launcher would have had 3 on the rails and been accompanied by a supply truck with more), ensuring no civilians are in the area means any aircraft in sight from then on is Ukrainian.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-09-30T20:16:46.620" LastActivityDate="2015-09-30T20:16:46.620" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21434" PostTypeId="2" ParentId="21396" CreationDate="2015-09-30T20:53:18.113" Score="9" Body="&lt;p&gt;Yes. If a US-registered aircraft is to be operated at night, it must carry:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.205&quot;&gt;§91.205&lt;/a&gt;(c)(6) One spare set of fuses, or three spare fuses of each kind required, that are accessible to the pilot in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now, as far as other types of spares go - no clue! But &lt;em&gt;some&lt;/em&gt; spares must be carried if certain requirements are met - eg, your airplane has fuses accessible from the cockpit. In the event of an electrical problem, the flight crew can replace the fuse as required.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-09-30T20:53:18.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21435" PostTypeId="1" CreationDate="2015-09-30T20:58:40.453" Score="4" ViewCount="1196" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iF4VD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iF4VD.jpg&quot; alt=&quot;4 pictures of aircraft in black and white&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are several photos of older aircraft I'd like help in naming. Year, Model, &amp;amp; Manufacturer.&#xA;Thanks so much.&#xA;Ron&lt;/p&gt;&#xA;" OwnerUserId="11478" LastEditorUserId="11478" LastEditDate="2015-09-30T22:14:15.840" LastActivityDate="2019-06-07T02:08:57.903" Title="What are the types of these 3 single-engine aircraft and one Multi engine aircraft?" Tags="&lt;aircraft-identification&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21436" PostTypeId="2" ParentId="21240" CreationDate="2015-09-30T21:11:27.327" Score="1" Body="&lt;p&gt;The major reason for going away from trijet was a series of total hydraulic failures following an uncontained engine failure. This happened in both the L1011 and the MD-10 (but not the 727)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an engine failed, high speed debris from the failed engine would cut the hydraulic system and control cables. The result was an airplane without conventional controls. For the most part the result was a total loss. In the case of the Souix City event, &lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;four pilots were able to land the plane (almost) and the resulting crash only killed about 1/3 of the passengers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not a good idea, three engines.&lt;/p&gt;&#xA;" OwnerUserId="11479" LastActivityDate="2015-09-30T21:11:27.327" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21437" PostTypeId="1" CreationDate="2015-09-30T21:22:14.727" Score="6" ViewCount="8694" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oE3CM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oE3CM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On this RNAV approach plate, what is the missed approach point for the LNAV MDA approach? How do you arrive at this answer?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2019-06-08T20:48:51.567" Title="How to determine the MAP for an RNAV MDA approach?" Tags="&lt;non-precision-approach&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21438" PostTypeId="2" ParentId="21435" CreationDate="2015-09-30T21:23:41.453" Score="1" Body="&lt;p&gt;The lower left picture shows a Beech 18 Twin Beech, built in the 1930's. &#xA;On the tail the markings N and 15 are visible. Since all other aircraft show registrations starting with NC and they all feature the same control tower (apart from the top left picture) I assume all photo's are from the same year. It is likely the registration of the Beech 18 starts with NC too. The only Beech 18 Twin Beech in &lt;a href=&quot;http://www.warbirdsdirectory.goodall.com.au/beech18-production/beech18-part-1.pdf&quot; rel=&quot;nofollow&quot;&gt;this production list&lt;/a&gt; with a NC registration is the first ever built, with registration NC15810.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower right picture shows a North American Texan Yale, registration NC61032. It is listed in &lt;a href=&quot;http://www.goodall.com.au/warbirds-directory-v6/north-american-texan-yale.pdf&quot; rel=&quot;nofollow&quot;&gt;this production list&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-09-30T21:39:37.973" LastActivityDate="2015-09-30T21:39:37.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21440" PostTypeId="2" ParentId="21435" CreationDate="2015-09-30T21:27:40.867" Score="5" Body="&lt;p&gt;From left to right, top to bottom, and from memory I'm guessing a Fairchild PT-19, a BT-13, a Beech D18, and a North American AT-6. The BT-13 had a 450 horse P&amp;amp;W. which they'd pull off that airplane and put on Stearman to make a duster/spray plane out of. All of these airplanes were really cheap after WW2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I remember, AT-6s sold after the war for as little as 500 USD, but then when the Korea War came along, the government wanted them back and were paying up to 30,000 for them.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-09-30T22:19:29.440" LastActivityDate="2015-09-30T22:19:29.440" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21441" PostTypeId="2" ParentId="21435" CreationDate="2015-09-30T21:37:57.327" Score="8" Body="&lt;p&gt;The upper left one looks like a Fairchild PT-19-family monoplane trainer. Production on these started in 1939 and served through the end of the war as a basic trainer. Yours might just be the PT-19B variant, which has a hood over the front cockpit and was used for instrument training:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Nqeq0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nqeq0.jpg&quot; alt=&quot;PT-19&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The upper right one looks like a Vultee BT-13 or BT-15 &quot;Valiant&quot; basic trainer, which were used as Air Force and Navy basic trainers from 1940 to 1944:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/z9xle.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z9xle.jpg&quot; alt=&quot;BT-13&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower left is actually a twin-engine plane, not a single, looks like a variant of the Beechcraft Model 18, or &quot;Twin Beech&quot;. These were built beginning around 1937 and continued well into the Vietnam years. Military designations include the C-45 Expeditor, AT-7 Navigator, and AT-11 Kansan, but your specific example appears to be civilian:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/yjUI3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yjUI3.jpg&quot; alt=&quot;Beech Model 18&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower right is a North American T-6 or AT-6 Texan. Production on these began in 1933 and they were only retired from all air forces in 1996 (though the last operator, South Africa, only kept them as basic trainers because a military embargo related to its Apartheid policy prevented them buying anything newer):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DSfOL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DSfOL.jpg&quot; alt=&quot;T-6&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as exact build dates of these aircraft, you might be able to look up the tail numbers of each airplane, but these craft were so common and so varied during their production that exactly when a specific airframe was built is difficult to determine by looking at it. All of these aircraft, in addition, seem to have been &quot;civilianized&quot; after service with the USAAC/USAAF, so their full history may be very hard to trace without their logbooks.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="22726" LastEditDate="2019-06-07T02:08:57.903" LastActivityDate="2019-06-07T02:08:57.903" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="21442" PostTypeId="2" ParentId="21435" CreationDate="2015-09-30T21:40:21.163" Score="0" Body="&lt;p&gt;The first is a Fairchild PT-19 trainer (~1940). The second looks like a Vultee BT-13 or BT-15 (~1940). The third looks like an AT-11 (~1937), and the forth is an early T-6 or AT-6A (~1937). &lt;/p&gt;&#xA;" OwnerUserId="11481" LastActivityDate="2015-09-30T21:40:21.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21445" PostTypeId="2" ParentId="21427" CreationDate="2015-09-30T23:01:01.900" Score="2" Body="&lt;p&gt;The turning radius R is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R \ = \frac{V^{2}}{11.26 \  tan \theta}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;V is the true airspeed in knots&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;R is turning radius in feet and&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;θ is the bank angle in degrees&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the glider is turning at a radius greater than the tow plane, i.e. it is in the outside of the turn, it must be flying at a higher speed in order to complete each circle in the same time. For glider in the inside turn, the opposite is true i.e. the glider is flying at lower speed compared the tow plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wkhL5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wkhL5.png&quot; alt=&quot;Turning inside towplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;FAA Glider Flying Handbook&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also for outside turn, the bank angle of the glider should be higher than the  tow aircraft to compensate for the higher speed. The reverse is true &#xA;for an inside turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YPOGR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YPOGR.png&quot; alt=&quot;Turning outside towplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;FAA Glider Flying Handbook&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, the only way the two aircraft can fly coordinated with the same bank angle is if they have the same speed and turning radius.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying the glider in inside of a turn is preferred because it is easy to give corrections (to have same speed and turning radius) compared to outside turn. The glider bank angle can be reduced till it returns to the correct position. Since the glider is flying at a lower airspeed (than the tow plane) it will accelerate as its turn radius increases so there will be no tendency for slack to develop in the tow line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For gliders in outside turn, the bank angle has to be increased to reduce the turn radius. However, as the glider is flying faster compared to the tow plane, it (glider) will tend to overtake it as turn radius is reduced, developing slack in the line unless airspeed is also reduced (usually by yawing the glider away from the towplane). In this case, the correction process is more difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason, &lt;a href=&quot;http://www.5c1.net/Aerotowing.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;it is advisable to&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...match the tow plane bank angle and point the nose of the glider at the tow plane's outer wing tip. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;at-least for small bank angles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, it is better to be &lt;a href=&quot;http://www.scottishairsports.co.uk/html/aerotowing.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;in the inside of turn rather than outside&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you have to err on one side or the other, it is better to err on the inside – especially when at a low altitude. This way, you’re not in as much danger of locking out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;as long as you are not too far inside so as to sink and stall.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-30T23:07:45.950" LastActivityDate="2015-09-30T23:07:45.950" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21446" PostTypeId="1" AcceptedAnswerId="21451" CreationDate="2015-09-30T23:06:16.040" Score="9" ViewCount="3074" Body="&lt;p&gt;Here is the picture  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ldZzP.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ldZzP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source:(brians-travels.com)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This looks like a photoshopped picture, but I believe it isn't. Is this some kind of strange occurrence that occurs only with the human eye? The blade on the top looks bent downwards. I can't figure out what happened in this picture. And will your picture look like this every time you take a picture of a fast moving propeller?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3201" LastEditDate="2015-10-02T10:23:50.560" LastActivityDate="2015-10-04T18:32:48.977" Title="What happened to the blades in this picture?" Tags="&lt;propeller&gt;" AnswerCount="3" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="21447" PostTypeId="1" CreationDate="2015-09-30T23:12:04.527" Score="2" ViewCount="16304" Body="&lt;p&gt;I don't mean carry on bags. What I mean is where are the locations of the non carry on bags on an airliner. Also does it depend on the airliner of where the bags are stored.&lt;a href=&quot;https://i.stack.imgur.com/Nf6Y7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nf6Y7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:(gokaysarioz.com)&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2020-05-16T21:15:21.490" Title="Where are the bags generally stored on an airliner?" Tags="&lt;baggage-handling-system&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21448" PostTypeId="2" ParentId="21446" CreationDate="2015-09-30T23:15:03.810" Score="1" Body="&lt;p&gt;This is an effect produced by the digital camera that took the picture. The CMOS sensor &quot;scans&quot; the picture from one edge to another, possibly bottom to top in this example. Each line of the photo is taken at a slightly different time, and the prop moves fast enough that it moves a little bit in between each scan line. After the camera puts all the scan lines together into an image, you can get the effect you see here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read more about this effect at &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolling_shutter&quot; rel=&quot;nofollow&quot;&gt;Rolling shutter&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-09-30T23:15:03.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21449" PostTypeId="2" ParentId="21446" CreationDate="2015-09-30T23:15:21.073" Score="6" Body="&lt;p&gt;This is a result of the way the camera shutters operate. Usually, the cameras don't capture images in the same way as human eye i.e. they don't take image of the whole scene simultaneously but rather 'scans' horizontally or vertically. In normal cases, this &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolling_shutter&quot; rel=&quot;nofollow noreferrer&quot;&gt;rolling shutter&lt;/a&gt; method is not a problem, but can cause issues when the object is moving at high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quote from user &lt;a href=&quot;http://theaviationist.com/2011/01/17/photo-flying-with-bent-propeller-blades-or-mobile-phones-camera-oddity/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FGK&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The plenomenon is due to Rolling shutter (also known as line scan) is a method of image acquisition in which each frame is recorded not from a snapshot of a single point in time, but rather by scanning across the frame either vertically or horizontally. In other words, not all parts of the image are recorded at exactly the same time, even though the whole frame is displayed at the same time during playback. This in contrast with global shutter in which the entire frame is exposed for the same time window. This produces predictable distortions of fast-moving objects or when the sensor captures rapid flashes of light.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3fAMQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3fAMQ.jpg&quot; alt=&quot;Rolling shutter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: ephotozine.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, it is due to camera rather than the propeller blades themselves. The effect of a simulated rolling shutter on a spinning disc shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GUt8Q.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GUt8Q.png&quot; alt=&quot;Rolling shutter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Rolling_shutter_effect.svg#/media/File:Rolling_shutter_effect.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolling shutter effect&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Cmglee&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Cmglee&quot;&gt;Cmglee&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-09-30T23:24:03.907" LastActivityDate="2015-09-30T23:24:03.907" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21451" PostTypeId="2" ParentId="21446" CreationDate="2015-09-30T23:15:45.923" Score="27" Body="&lt;p&gt;It's an artifact of how a digital camera downloads captures the image from the sensor called &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolling_shutter&quot; rel=&quot;nofollow noreferrer&quot;&gt;rolling shutter&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially the image is captured a single line at a time and the fast moving propeller changes location between each line captured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Rolling_shutter_effect.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia has a nice diagram&lt;/a&gt; showing what happens step by step:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Rolling_shutter_effect_animation.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9oiTb.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On our sister site photography.SE has &lt;a href=&quot;https://photo.stackexchange.com/a/9528&quot;&gt;a question asking about it.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:44:06.937" LastActivityDate="2015-09-30T23:29:30.930" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21452" PostTypeId="1" AcceptedAnswerId="21456" CreationDate="2015-09-30T23:17:07.613" Score="8" ViewCount="3071" Body="&lt;p&gt;Given that during acrobatics, extreme G-forces may be impressed upon the fuel tank, wouldn't it make it somewhat difficult for fuel to get to the fuel pump while it's being pushed against a specific direction for the duration of the stunt? Is the solution just not to do the stunt long enough to starve the engine of fuel?&lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-10-02T23:27:20.183" Title="How does fuel get to the engine during acrobatics?" Tags="&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21453" PostTypeId="2" ParentId="21447" CreationDate="2015-09-30T23:28:52.597" Score="6" Body="&lt;p&gt;On a modern large airliner (particularly for long haul), the bags are loaded into a &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;ULD (Unit Load Device)&lt;/a&gt; which are the big silver boxes that you see on airport ramps. These ULDs are then loaded into the cargo hold of the aircraft, which is located directly below the passenger deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a photo of the empty cargo hold of an A320 &lt;a href=&quot;https://www.atsb.gov.au/publications/investigation_reports/2009/aair/ao-2009-034.aspx&quot; rel=&quot;noreferrer&quot;&gt;(source)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q1L0G.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this is what it looks like in cross-section after loading (this is an A300) &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Airbus_A300_cross_section.jpg&quot; rel=&quot;noreferrer&quot;&gt;(source)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gUuZL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gUuZL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="675" LastEditDate="2015-10-01T00:18:22.333" LastActivityDate="2015-10-01T00:18:22.333" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21454" PostTypeId="2" ParentId="21452" CreationDate="2015-09-30T23:46:37.713" Score="2" Body="&lt;p&gt;There are a few different types of acrobatic fuel systems but there are specialized fuel systems for acrobatic planes for this very mater. The FAA has a nice &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_ch14.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;document covering it here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For acrobatic category airplanes, excessive loss of fuel during&#xA;  acrobatic maneuvers, including short periods of inverted&#xA;  flight, must be prevented. It must be impossible for fuel to&#xA;  siphon from the vent when normal flight has been resumed&#xA;  after any acrobatic maneuver for which certification is&#xA;  requested.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-flying-upside-down-27746739/?no-ist&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; cites at least one way of doing it. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To ensure the flow from fuel tank to fuel injector, aerobatic aircraft with the fuel tank in the fuselage have a “flop tube,” a flexible hose with a weight in the free end, plugged into the fuel tank&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And here is another question on how &lt;a href=&quot;https://aviation.stackexchange.com/questions/1183/do-fighter-jets-have-a-traditional-inverted-fuel-system&quot;&gt;fighter jets do it&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-01T00:45:19.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21455" PostTypeId="2" ParentId="21447" CreationDate="2015-09-30T23:46:49.497" Score="9" Body="&lt;p&gt;In smaller aircraft, the baggage is put directly inside the cargo hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bizI8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bizI8.jpg&quot; alt=&quot;Baggage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: jacksonville.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of larger aircraft, the baggage is put inside the conformal cargo container or the unit load device, which is then placed inside the cargo hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GGqsB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GGqsB.jpg&quot; alt=&quot;Baggage container&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: roger-wilco.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xOkus.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xOkus.jpg&quot; alt=&quot;Cargo hold&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: supath.net&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-09-30T23:46:49.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21456" PostTypeId="2" ParentId="21452" CreationDate="2015-10-01T00:16:18.980" Score="13" Body="&lt;p&gt;The basic problem is that no matter how the aircraft's fuel tanks are designed, if there is an air gap in the tank, then there is an attitude and/or a g-loading that puts that air gap over the inlet to the fuel line running to the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a lot of solutions to this problem. The first is exactly as you say; don't sustain any maneuver that starves the fuel pump (and by extension the engine) for a longer period than you have fuel in the lines to feed the engine. You can actually do a lot without the fuel system seeing a single hiccup in supply; the fuel tanks are designed to feed while under positive G-load (otherwise you couldn't get any fuel to the engine just sitting on the tarmac), so hard turns, rolls, loops etc that keep a force on the aircraft and its contents acting downward towards the floor of the cockpit will keep the fuel flowing into the engine. Spins and high negative-G maneuvers tend to be the things that starve the engine; if the tanks are in the wings, a hard spin, snap roll or zero-g parabola will push the fuel out away from the inlets at the wing roots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most fuel systems except on the lightest aircraft have at least two fuel pumps per engine; one electric pump on the tank side to shove fuel into the line, and one crankshaft-powered pump that draws fuel out of the lines into the carb chamber or other fuel delivery system. The checklist often involves turning on the electric fuel pumps just before startup to prime the fuel lines, then turning them off once the engine is running smoothly, but you can keep the electric pump on if you plan on really twerking the aircraft in flight. The line between these two pumps actually holds a fair amount of fuel, plenty for a minute or more of sustained operation with the inlet at the tank totally starved, and coupled with a bleed valve on the engine side to release any air that's entered the line, the two pumps running together can usually keep an uninterrupted flow of fuel into the engine by having the electric pump shove fuel down the line as fast as it can whenever the inlet is under the liquid level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For mild aerobatic maneuvers, a &quot;flop tube&quot; is put into the fuel tank. This is simply a flexible hose with a weight, that keeps the hose under the liquid level, no matter what forces are acting to move the mass of liquid around in the tank. This is a simple and very effective way to keep fuel flowing to the engine while the aircraft is under load in any direction, but because the flop tube requires a significant volume of fuel to sink underneath and draw from, flop tubes can increase the &quot;unusable fuel&quot; capacity of the aircraft (fuel that exists in the tank, but the fuel system can't draw out in some normal circumstance). However, there's a tradeoff; the heavier the weight on the end of the flop tube, the more reliably it will stay under the fuel level regardless of attitude, but the more force with which it will impact the sides of the tank in violent maneuvers (and padding the weight further increases unusable fuel).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the real aerobatic nuts, though, the maneuvers are so violent and so long that even a flop tube, redundant fuel pumps and bleed valves might get starved as the fuel sloshes and churns and there isn't a real &quot;liquid level&quot; to draw from. Many of these aircraft go one step further; a bladder-style fuel container. Within the fuel tank is a flexible polymer vessel that actually holds the fuel (typically in either wingtip tanks or a fuselage tank; it's usually impractical to try this with in-wing tanks). This bladder keeps the liquid and gas in the tank shell separate as the tank empties, and may also keep the fuel under some static pressure. If there's no air to draw into the fuel lines, then no matter how the aircraft is oriented or how many Gs it's pulling in any direction, the fuel lines can't be starved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the fuel lines are only one consideration. Most &quot;normal&quot;-rated aircraft have float-type carburetors, which hold a reservoir of fuel with another air gap, and the fuel level in the reservoir is controlled by a float that opens the inlet from the fuel pump (this system also deals with small hiccups in the fuel flow from the tanks; the air just forms part of the air gap and the float keeps the inlet open until fuel flows in to raise the level). This type of carb will starve the engine during any maneuvers involving less than 1g of force acting towards the &quot;floor&quot; of the float chamber, as the float will keep the inlet closed and the reservoir will starve the fuel feed tube that allows fuel to dribble into the throttle body at the throat. For aerobatics, either a diaphragm-chamber carb (which has a flexible wall on one side of the reservoir chamber that is connected to the fuel inlet) or a fuel injection system must be used to avoid dependence on gravity to get fuel into the engine. The downside of these systems are increased complexity, and in the case of the diaphragm-chamber carb, intolerance of air this far along the fuel system (requiring an air bleed to purge any bubbles in the line before the fuel enters the reservoir).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-01T22:34:20.703" LastActivityDate="2015-10-01T22:34:20.703" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21458" PostTypeId="2" ParentId="12212" CreationDate="2015-10-01T01:21:04.713" Score="3" Body="&lt;p&gt;In most cases, only if he is not on-duty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most transoceanic flights have flight times exceeding the amount of time a pilot is allowed by most aviation regulators to be at the yoke in one stretch. In the U.S., the FAA mandates a maximum of 8 hours in one continuous block, which can be extended by a few hours if the pilot is then allowed to rest for a longer-than-normal time afterward. Qantas Flights 7 and 8 between Dallas and Sydney are in the air for &lt;em&gt;sixteen and a half hours&lt;/em&gt; in one continuous flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these situations, the aircraft has multiple flight crews, and one crew will relieve the other in mid-flight. While not on duty, pilots may do almost anything the confines of the plane allow, including retiring to a special pilots' quarters, usually tucked in an out-of-the-way place on the plane, not obvious to passengers. These quarters, while not exactly palatial, are still of a level that even first class passengers would envy:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oW8WM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oW8WM.jpg&quot; alt=&quot;787 Pilot&amp;#39;s Rest Cabin&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://s3files.core77.com/blog/images/2014/08/0airplanecrc-004.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;core77.com&lt;/a&gt;)&lt;/sub&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin crew also have an hours limit that is exceeded by most long-hauls, and they also have their own space to get away from their jobs, though it's slightly more spartan:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/otxCE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/otxCE.jpg&quot; alt=&quot;A380 Crew Rest Cabin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While on-duty, the FAA regs used to allow for &quot;in-seat rest&quot;, allowing the &quot;pilot not flying&quot; to rest his eyes for a while if nothing interesting was going on. However, an incident with Northwest Airlines Flight 188 in 2009 was the final nail in the coffin for any allowance for sleeping in the cockpit. ATC lost all communication with this flight for almost two hours while it was heading to Minneapolis. By the time contact was re-established, the plane was 150 miles past the airport and still at cruising altitude. In the interim, F-16s were readied to intercept (but never launched) as the plane had been feared hijacked. While the pilots insist they were using laptops to go over airline schedules (a breach of Northwest's parent Delta's cockpit policies, not to mention basic flight fundamentals), other theories suggest they simply fell asleep. Unfortunately, the CVR only had the last 30 minutes of the flight in its data buffer, while the critical time to determine what they'd been doing before radio contact was re-established would have been at least an hour prior to landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;British Airways and Qantas as well as a few other airlines do allow pilots on duty to sleep in the cockpit, as long as one crew member is awake and at the controls. However, they cannot do so while flying in U.S.-controlled airspace.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-04-13T08:40:59.723" LastActivityDate="2019-04-13T08:40:59.723" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21459" PostTypeId="2" ParentId="21396" CreationDate="2015-10-01T02:27:14.843" Score="0" Body="&lt;p&gt;Normally planes don't have major spare parts. Instead of parts they have redundancy in almost every flight system, which under certain circumstances an experienced pilot can take advantage of in order to keep operating the plane safely. Have in mind that the weight issue in a plane is very important. That's why a popular phrase between pilots says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Every takeoff is optional, but landing is&lt;/em&gt; &lt;strong&gt;mandatory&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11490" LastEditorUserId="4379" LastEditDate="2015-10-01T17:55:32.377" LastActivityDate="2015-10-01T17:55:32.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21460" PostTypeId="1" AcceptedAnswerId="21465" CreationDate="2015-10-01T03:54:52.347" Score="4" ViewCount="840" Body="&lt;p&gt;Then have been three incidents (UAL232, JAL123 and DHL 00-DLL) where damage to an aircraft resulted in complete loss of hydraulics. Only one of them managed to make it down safely using differential thrust. Each plane was from a different manufacturer. All three aircraft had triple or quadruple redundant systems. This seems like plenty of redundancy, but the Achilles heel is that, regardless of how the systems are piped around the aircraft they all have to converge at each of the control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is why did damage in one part of each hydraulic system result in loss of the entire system? For example in the DHL incident the left wingtip was damaged with all three lines. Is there not a way to isolate that wing and cut off hydraulic flow to protect the integrity of the rest of the system? You would lose control surfaces on that wing, but still have elevator, rudder and the other wing. Do any aircraft have a way of preventing this?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2019-03-14T08:38:27.400" Title="Why could these aircraft not prevent total hydraulic failure?" Tags="&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21461" PostTypeId="1" AcceptedAnswerId="21462" CreationDate="2015-10-01T05:39:07.593" Score="5" ViewCount="391" Body="&lt;p&gt;We all know certain weather can cause ice to form on an aircraft, and the danger it poses. Obviously the best way is to avoid flying near these areas in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I happen to fly into one. Aircrafts have de-ice equipment such as de-icing boots, pitot heat, engine de-ice etc; but sitting there and flying through the ice-cold cloud does not seem to be a good idea. So &lt;em&gt;something&lt;/em&gt; must be done to get the aircraft out of icing conditions asap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best course of action? Should I descend at normal speed? Or descend and pick up speed? Climb? Perform a 180? Would a weather radar (which reflects precipitations) help?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-10-01T06:09:47.810" Title="How to get out of icing conditions asap?" Tags="&lt;safety&gt;&lt;weather&gt;&lt;icing&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21462" PostTypeId="2" ParentId="21461" CreationDate="2015-10-01T06:09:47.810" Score="3" Body="&lt;p&gt;well, you'd have to fly in whatever is the shortest route out of the icing conditions, obviously.&lt;br/&gt;&#xA;What that would be depends on your speed, wind, climb/descent performance, and how you entered icing conditions.&lt;br/&gt;&#xA;If you entered icing by climbing, diving may well get you out of it (but if you were climbing to avoid terrain...).&lt;br/&gt;&#xA;If you were turning left, turning right might do it (but were you turning left to avoid collisions?).&lt;br/&gt;&#xA;Etc. Etc.&lt;br/&gt;&#xA;IOW there's no universal answer, it's way too situational.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-10-01T06:09:47.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21463" PostTypeId="2" ParentId="21437" CreationDate="2015-10-01T06:11:54.050" Score="5" Body="&lt;p&gt;The Missed Approach Point (MAPt) is at the runway threshold. The other reference you will see on this RNAV chart is the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/#ifpprofileview&quot; rel=&quot;noreferrer&quot;&gt;Visual Descent Point&lt;/a&gt; (VDP), at 1.1NM RWY05R, which is at the Minimum Descent Altitude (MDA).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The concept of VDP was developed by the FAA to encourage pilots to decide to initiate a missed approach prior to reaching the MAP, in a situation where the runway or its environment is not visible at a normal descent angle. Conversely, if the runway is visible at the VDP, the pilot may continue descent, following a standard descent angle to the runway, while being assured terrain and obstacle clearance.[5] The VDP is always located prior to reaching the MAP, and is a more useful checkpoint for making the decision whether to continue on the approach or to go around than the MAP itself.&lt;br&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Missed_approach_point&quot; rel=&quot;noreferrer&quot;&gt;WikiPedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the MAPt is intended to be elsewhere, it will be assigned its own identifier.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The missed approach waypoint is assigned a pronounceable name when it is not located at the runway threshold.&quot; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: AIM 5-4-5.d.5(d))&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Uwkz4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uwkz4.jpg&quot; alt=&quot;RNAV Approach Plate&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/#ifpprofileview&quot; rel=&quot;noreferrer&quot;&gt;www.faa.gov&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-10-01T06:30:23.717" LastActivityDate="2015-10-01T06:30:23.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21464" PostTypeId="1" CreationDate="2015-10-01T06:50:41.730" Score="12" ViewCount="2431" Body="&lt;p&gt;Apparently jet engines can take several seconds, up to ten or fifteen seconds, to go from full power to idle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? Can't a simple fuel valve shut off fuel flow? Or reduce it to whatever flow rate corresponds to idle? Either of these, if done with a valve, should happen almost instantly as far as I can tell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would surely cut thrust, regardless if the engine still spins for a while. Is there something dangerous about this idea? To me it seems like a fuel valve can close and open again as many times as it wants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I'm interested in turbojets and turbofans. And I care about throttling &lt;strong&gt;down&lt;/strong&gt; only.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2017-12-23T18:20:27.337" Title="Why do jet engines take a long time to throttle down?" Tags="&lt;jet-engine&gt;&lt;military&gt;" AnswerCount="3" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="21465" PostTypeId="2" ParentId="21460" CreationDate="2015-10-01T06:52:11.753" Score="9" Body="&lt;p&gt;There is no general answer, but the closest one would be bad luck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the DC-10-10, the aircraft of &lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow noreferrer&quot;&gt;UAL232&lt;/a&gt;, all three hydraulic lines went through one hole in the tail bulkhead which was damaged when the engine failed. This is no real redundancy, and it was bad luck that this particular spot had been hit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Tristar&lt;/a&gt;, the same accident would had damaged probably just one line. There, the three hydraulic lines are separated as much as possible in the tail section (one on top, one on the left side and one of the right side of the fuselage). Lockheed has more experience with military design than Douglas, so the Lockheed engineers were more aware of redundancy issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the A300 involved in the &lt;a href=&quot;https://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shootdown_incident&quot; rel=&quot;nofollow noreferrer&quot;&gt;Baghdad attempted shoot-down incident&lt;/a&gt;, the same bad luck happened. Normally, each aileron is powered by two out of three hydraulic circuits, so one would remain if the other two are hit. Note that the green and yellow circuits were lost immediately, while the blue circuit failed only &lt;a href=&quot;https://www.google.de/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=3&amp;amp;ved=0CDEQFjACahUKEwil8Z2D1qDIAhWFXBoKHay7COM&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DBaghdad_A300_Incident.pdf&amp;amp;usg=AFQjCNE3hfi1kbSw4JjnuvZ4GoyQ_hJFtw&amp;amp;bvm=bv.104226188,d.d2s&quot; rel=&quot;nofollow noreferrer&quot;&gt;20 seconds later&lt;/a&gt;. But in this case the damage extended to the spoilers, so all three circuits were affected in the end. There is only so much damage you can protect against.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also for &lt;a href=&quot;https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot; rel=&quot;nofollow noreferrer&quot;&gt;JAL123&lt;/a&gt; the damage was just too extensive to not involve all four hydraulic circuits. The rear pressure bulkhead burst and blew most of the vertical tail surface away. It can be argued that the real culprit, however, was the chief pilot's refusal to don his oxygen mask. But the aircraft was only marginally stable and &lt;a href=&quot;https://aviation.stackexchange.com/questions/13728/what-alternative-methods-are-there-for-controlling-a-plane-when-flight-control-s/13731#13731&quot;&gt;very hard to control&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydraulic fluid needs to be pumped continuously to heat it so its viscosity stays low. If you add shutoff valves, this pumping could be impeded. Note that the spoilers of the Baghdad A300 were not sucked open because non-return valves blocked the lines to the spoilers, helping in keeping the aircraft flyable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you put shutoff valves along the hydraulic lines, you open up a new avenue for failures. The idea of hydraulics is that you use just one pump and can create the maximum force at any point, since rarely would you need to move several actuators at maximum load in parallel. Splitting up the circuitry to enable the pilot to isolate parts of the airplane will take away this advantage, resulting in a more complex, heavier hydraulic system. And who knows if those added parts would not malfunction or be mishandled, resulting in a new class of entirely avoidable accidents.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-03-14T08:38:27.400" LastActivityDate="2019-03-14T08:38:27.400" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="21466" PostTypeId="1" CreationDate="2015-10-01T07:31:56.203" Score="9" ViewCount="25928" Body="&lt;p&gt;I have some questions on interpreting Exhaust Gas Temperature (EGT) readings.  Can you give me some input on:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What appears on EGT Gauge if the mixture is lean or rich?&lt;/li&gt;&#xA;&lt;li&gt;what is the normal range, high range, and low range for EGT?&lt;/li&gt;&#xA;&lt;li&gt;What is the relationship between the EGT and rich or lean&#xA;mixture?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="11494" LastEditorUserId="64" LastEditDate="2015-10-01T18:58:10.827" LastActivityDate="2020-06-09T11:54:21.230" Title="What appears on EGT Gauge if the mixture is rich or lean?" Tags="&lt;engine&gt;&lt;piston-engine&gt;&lt;temperature&gt;&lt;egt&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21467" PostTypeId="1" AcceptedAnswerId="21471" CreationDate="2015-10-01T07:54:39.763" Score="4" ViewCount="1650" Body="&lt;p&gt;This image had me intrigued:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jTC4R.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jTC4R.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;It looks like two semi-circles, the upper part for passengers and the lower part for cargo.&lt;/p&gt;&#xA;&lt;p&gt;I was wondering, for short haul flights, could the lower part be converted like the upper part, so the plane could carry more passengers, like a basement stuff, no windows and lower fares. We could do away with cabin luggage and stuff to take care of maximum takeoff weight, and anyways my thought was towards short haul flights.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-06-22T19:20:38.310" Title="Could the cargo hold of an aircraft be re-designed to carry passengers?" Tags="&lt;cabin-design&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21469" PostTypeId="1" AcceptedAnswerId="21475" CreationDate="2015-10-01T08:46:15.697" Score="1" ViewCount="382" Body="&lt;p&gt;Reading this article about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_E-8_Joint_STARS&quot; rel=&quot;nofollow&quot;&gt;Northrop Grumman E8&lt;/a&gt; it says the the aircraft will be able to fly higher after engine upgrades. Wouldn't the max service ceiling be limited by the fuselage design too?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="5517" LastEditDate="2016-02-18T20:59:14.033" LastActivityDate="2016-02-18T20:59:14.033" Title="Is it the engines or the fuselage that limits service ceiling?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-10-01T15:26:09.530" ContentLicense="CC BY-SA 3.0" />
  <row Id="21470" PostTypeId="1" AcceptedAnswerId="21587" CreationDate="2015-10-01T08:49:17.253" Score="2" ViewCount="585" Body="&lt;p&gt;On airliners, the safety demonstration includes many items (seat belt, life vest, evacuation, etc.) and each of those items may raise questions from the passengers (&lt;a href=&quot;https://aviation.stackexchange.com/questions/2528/why-shouldnt-you-inflate-your-life-vest-until-youre-outside-the-airplane/&quot;&gt;when to inflating the life vest&lt;/a&gt;, how to unlocking the seat belt, ...) and thus need more time to explain why those items are detailed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the following elements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the safety demonstration should begin &lt;a href=&quot;https://aviation.stackexchange.com/questions/21397/why-are-safety-demonstrations-done-while-taxiing/21425&quot;&gt;while leaving the gate&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;an average passenger may not pay attention for more than few minutes&lt;/li&gt;&#xA;&lt;li&gt;the briefing should be finished before take-off (I hardly see flight attendants moving and manipulating life vest, seat belts and other objects in the middle of the aisle while taking off)&lt;/li&gt;&#xA;&lt;li&gt;many items may need a better (and longer) explanation&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I have several questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Are there any regulations about the timing of the safety demonstrations?&lt;/li&gt;&#xA;&lt;li&gt;Is it up to the airline (automated videos are quite easy to time)? &lt;/li&gt;&#xA;&lt;li&gt;What if the safety demonstration are not finished when the aircraft is ready to take off (on the runway with all clearances)?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-05T16:17:50.170" Title="What are the safety demonstration time-constraints?" Tags="&lt;safety&gt;&lt;airliner&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21471" PostTypeId="2" ParentId="21467" CreationDate="2015-10-01T10:01:09.053" Score="12" Body="&lt;p&gt;In principle, yes. The cargo hold is &lt;a href=&quot;https://aviation.stackexchange.com/questions/8252/are-cargo-holds-pressurised-these-days&quot;&gt;pressurised&lt;/a&gt; and (depending on the aircraft and the installed options) reasonably temperature-controlled. However, it's probably not feasible; there are three major issues to be worked out that I can think of off the top of my head:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cargo hold height and windows. It's a bit hard to tell from your picture, but even on a large widebody plane the cargohold is not that high (the cabin floor is lower than halfway). The A330 (as an example) carries &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device#Types&quot; rel=&quot;noreferrer&quot;&gt;LD3 containers&lt;/a&gt; in its cargohold, which are about 160cm tall; the cargohold is not much taller than that. Most passengers cannot walk upright inside it; the cargo hold on smaller aircraft is even lower (the one on the A320 is designed to carry LD3-46 containers, which have a height of about 115cm). Also, the lack of windows would bother passengers in the lower deck. &lt;/li&gt;&#xA;&lt;li&gt;Emergency exits. In an emergency, passengers must be able to get out of the plane within 90 seconds. At best you would need to install additional doors in the cargo hold; at worst, you will not be able to meet this requirement (because of the low ceiling, people can't move as quickly) &lt;/li&gt;&#xA;&lt;li&gt;In a crash landing, the lower fuselage may buckle, which serves to cushion the impact for the people in the passenger cabin. You would need to show that the passengers in the lower deck can survive a crash landing. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that some airlines use part of their lower deck for galleys, crew rests and even &lt;a href=&quot;http://www.airliners.net/photo/0686097/M/&quot; rel=&quot;noreferrer&quot;&gt;lavatories&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-10-01T10:01:09.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21472" PostTypeId="2" ParentId="21469" CreationDate="2015-10-01T10:15:37.573" Score="4" Body="&lt;p&gt;The only 2 problems of the fuselage is pressure and temperature. Pressure is not that much a problem, because the pressure difference will never be more than 1 atm. (The pressure at 50k ft is not that much lower than at 30k ft, in absolute numbers.) The temperature shouldn't pose a problem either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the motors, they need oxygen to operate, and the higher you go, the less oxygen you get.&lt;/p&gt;&#xA;" OwnerUserId="802" LastActivityDate="2015-10-01T10:15:37.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21473" PostTypeId="1" AcceptedAnswerId="21481" CreationDate="2015-10-01T10:32:27.077" Score="7" ViewCount="594" Body="&lt;p&gt;When aircraft are detected by radar and their transponders 'ping' back to the radar site, this data is passed over data network cables to the air traffic controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there typically any specialist equipment (high safety certification?) to send the data from the radar site on to the data network? Or is it something as simple as a server/PC with a network card?&lt;/p&gt;&#xA;" OwnerUserId="11499" LastEditorUserId="19" LastEditDate="2016-07-28T16:32:42.113" LastActivityDate="2016-07-28T16:32:42.113" Title="How does a Secondary Surveilliance Radar send data?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;radar&gt;&lt;security&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21475" PostTypeId="2" ParentId="21469" CreationDate="2015-10-01T10:54:39.947" Score="7" Body="&lt;p&gt;Service ceiling is defined as the maximum altitude at which the aircraft can maintain a specified rate of climb (typically 500 feet/minute for jets).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The service ceiling is dependent on a number of design factors like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine power&lt;/li&gt;&#xA;&lt;li&gt;Engine efficiency at high altitudes&lt;/li&gt;&#xA;&lt;li&gt;Wing design&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The service ceiling is usually limited by a number of factors, and engine is important among them.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Thrust (or power) decreases with altitude (density) and at some point the aircraft reaches an altitude where even at the 'maximum rate of climb' speed, the engine will not be able to produce enough (excess) thrust to get the required rate of climb. This will be the service ceiling. Usually this is the limiting factor for GA aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of very powerful engines, the wings may stop producing enough lift, though this is rarely the case.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of transport aircraft, the service ceiling may sometimes be limited by the maximum altitude from which they can descend to 14,000 ft in less than a specified time (4 min). Commercial airliners are usually limited by this certification altitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In commercial airliners, the cabin pressure altitude is held constant (usually ~8000 ft ISA) and the &lt;em&gt;differential pressure&lt;/em&gt; will cause stresses on the fuselage, but this is usually not the primary concern as fuselage design incorporates elements (for e.g. relief valves) to relieve pressure when this differential pressure goes beyond a limit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, usually it is the engine, rather than the fuselage that limits the service ceiling.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-01T10:54:39.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21476" PostTypeId="2" ParentId="21473" CreationDate="2015-10-01T10:59:51.243" Score="2" Body="&lt;p&gt;While I think that DeltaLima is the most suitable to answer that question, I will make an attempt from my experience in Hellenic airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The territory you want to controll has several RADAR installations. They may be primary, secondary or both. Each of these RADARs are connected to the ACC with a leased line (leased from National Telecomunications Organization in the case of Greece). I don't know of any specific protocols used (ASTERIX maybe? And I think X.25 on the data link layer). Then radar data from each individual RADAR is processed by the RDP (RADAR Data Procesor). RDP is a computer (maybe more than one) but you can't easily call it PC. The end result (containing position, ground speed, direction and altitude and Mode A code for the case of secondary radar covered track) is sent to the controller positions using a LAN protocol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can say that while the concept is similar to &quot;one PC with a network card&quot; the reality is much more complex, and has to do with safety, redundancy and very ofter with old hardware (you can't change RADARs or any other ATM equipment every 1 or 2 years just to have the latest of them).&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2015-10-01T10:59:51.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21477" PostTypeId="1" AcceptedAnswerId="21478" CreationDate="2015-10-01T11:18:48.953" Score="6" ViewCount="3774" Body="&lt;p&gt;An aircraft flying over a densely populated area–far away from the sea and mountains–declares an emergency, request fuel dump, and a landing as soon as possible. How does an air traffic controller know where it is safe/possible to dump fuel?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If this is regulated, then by whom or what is it regulated?&lt;/li&gt;&#xA;&lt;li&gt;If it's not regulated, by what criteria does an ATC use to determine an area for dumping?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2448" LastEditorUserId="878" LastEditDate="2015-10-01T11:38:38.660" LastActivityDate="2017-05-10T03:56:06.760" Title="What factors determine where an aircraft can dump fuel?" Tags="&lt;air-traffic-control&gt;&lt;fuel-dumping&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21478" PostTypeId="2" ParentId="21477" CreationDate="2015-10-01T12:03:13.930" Score="6" Body="&lt;p&gt;Fuel dumping &lt;em&gt;was&lt;/em&gt; regulated by FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/13937&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;Order 7110.65P - Air Traffic Control&lt;/em&gt;&lt;/a&gt;, which was canceled in 2006. FAA &lt;a href=&quot;http://www.faa.gov/airports/airport_development/omp/FAQ/General_Concerns/#q23&quot; rel=&quot;nofollow&quot;&gt;has the following to say&lt;/a&gt; regarding fuel dumping:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...If the need arises, aircraft are instructed by Air Traffic Control to dump fuel at high altitudes as far away from the airport or any populated areas as possible.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;At present, there are no hard and fast rules (at-least in US, for other countries, see below) regarding fuel dumping and it is left to the air-traffic controllers to guide the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main criteria in determining an are for fuel dumping are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-&lt;strong&gt;Altitude&lt;/strong&gt; In general, fuel jettisoned above 5000 ft will vaporize before reaching the ground. Due to this, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/AERO_Q307_article3.pdf&quot; rel=&quot;nofollow&quot;&gt;some manufacturers&lt;/a&gt; recommend fuel dumping above 5000 ft. In general, the ATC will guide the aircraft to an altitude where it can dump fuel so that it vaporises before reaching the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-&lt;strong&gt;Atmospheric conditions&lt;/strong&gt; The evaporative characteristics of the fuel dumped depends on the altitude and the atmospheric temperature. The aircraft fuel tends to vaporise faster in a warm day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-&lt;strong&gt;Aircraft separation&lt;/strong&gt; The ATC will try to keep a minimum lateral separation (~5 miles) between the aircraft dumping fuel and other aircraft and also some vertical separation (~2000 ft, according to Order 7110.65P).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except in case of safety emergency, the fuel dumping is carried out at high altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Some countries do have fuel dumping regulations, like &lt;a href=&quot;http://www.zurich-airport.com/~/media/flughafenzh/dokumente/das_unternehmen/laerm_politik_und_umwelt/2012_fuel_dumping_en.pdf&quot; rel=&quot;nofollow&quot;&gt;Switzerland&lt;/a&gt;, which says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The choice of the dumping area is determined by the urgency of the incident, the actual flight path, meteorological conditions and the general air traffic situation. The aircraft is led to a selected area by the air traffic control to dump fuel. At the minimum speed of 250 knots at an altitude of 6,000 ft, but usually with 350 knots at 14,000-16,000 ft fuel is dumped ... There exist no predefined dumping areas ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-01T14:14:58.417" LastActivityDate="2015-10-01T14:14:58.417" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21481" PostTypeId="2" ParentId="21473" CreationDate="2015-10-01T13:15:58.830" Score="7" Body="&lt;p&gt;I'll describe the typical Mode-S radar system based on my mostly European experience. Details will vary but the general concept applies world wide. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radio signal received from the aircraft is digitized, CRC checked,  compared to and combined with data from earlier transmissions from the aircraft. This data is usually encoded in ASTERIX format (typically &lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/service/content/documents/nm/asterix/cat048-asterix-tmtr-part4-v1.21-20120701.pdf&quot; rel=&quot;nofollow&quot;&gt;category 048&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;) and transmitted over a datalink to a surveillance data processing system (SDPS) in the ATC centre. From the SDPS the data is further distributed to various client systems, among which the air traffic controller display system is one.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radar processing itself is partly dedicated hardware and partly COTS (commercial-off-the-shelf) infrastructure. This is housed in a standard server cabinet. Network components are typically COTS high quality systems and duplicated for redundancy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The datalink from the radar site to the ATC facilities can take many forms. Every country has its own regulator and local telecom market peculiarities, leading to a variety of implementations. Often a dedicated line will be used, usually with a backup line as well. Sometimes two telecom providers are used that have to provide fully independent data paths to the ATC centre. In a few cases radio links are used to connect surveillance systems, I know of surveillance systems (not radars) that use satellite links. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Within the ATC centre usually duplicated or triplicated networks are used for redundancy. These can be &lt;a href=&quot;https://en.wikipedia.org/wiki/Twisted_pair#Unshielded_twisted_pair_.28UTP.29&quot; rel=&quot;nofollow&quot;&gt;UTP&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Fiber-optic_communication&quot; rel=&quot;nofollow&quot;&gt;glassfibre&lt;/a&gt; networks. These are again based on COTS high availability/integrity components.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="4474" LastEditDate="2015-10-01T18:58:13.767" LastActivityDate="2015-10-01T18:58:13.767" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21482" PostTypeId="2" ParentId="21414" CreationDate="2015-10-01T13:29:23.327" Score="4" Body="&lt;p&gt;A propeller is always facing a headwind, it's called &quot;airspeed&quot;. I don't really know what to tell you, the wind relative to the ground doesn't matter to the airplane or the propeller, the wind hitting it head on does, and yes, as the airspeed increases the load on the prop is reduced and the RPM increases unless you have a constant speed propeller (and thus a governor that changes the pitch of the blade when the RPM increases to combat this).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wind shear does indeed change the airspeed momentarily (more so for larger aircraft with more momentum), but so does pitching over and diving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The net effect is that a &quot;headwind&quot; (as measured relative to the earth) will only affect your ground speed, and thus the time it takes to get to your destination. The headwind, as measured relative to the aircraft, is called airspeed, and is usually kept at some set value appropriate for the aircraft in cruise. If the airspeed increases abruptly, the RPM will increase slightly as the load decreases (air doesn't have to be accelerated as much), which is countered by the prop governor (if you have one) and the fact that the airplane will slow down to match the new headwind since you're not feeding it any more power to maintain the new higher airspeed.&lt;/p&gt;&#xA;" OwnerUserId="2" LastEditorUserId="2" LastEditDate="2015-10-01T13:35:10.357" LastActivityDate="2015-10-01T13:35:10.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21483" PostTypeId="2" ParentId="21477" CreationDate="2015-10-01T13:31:20.417" Score="4" Body="&lt;p&gt;In an emergency, pilots can dump fuel where and when they need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is preferred that dumping occur&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Above 10000 feet&lt;/li&gt;&#xA;&lt;li&gt;Clear of towns and cities&lt;/li&gt;&#xA;&lt;li&gt;Over water&lt;/li&gt;&#xA;&lt;li&gt;Away from areas where thunderstorms are expected&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://www.caa.co.uk/docs/33/CAP493%20Edition%206%20Amendment%201%20Corrigendum%20(April%202015).pdf&quot; rel=&quot;nofollow&quot;&gt;CAA Manual (MATS) Part 1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;13&quot;&gt;&#xA;  &lt;li&gt;Fuel Jettisoning&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;13.1 Pilots of aircraft in flight are permitted to jettison fuel in an emergency. The decision to jettison rests solely with the pilot but he may request guidance from ATC.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;13.2 When an aircraft in controlled airspace needs to dump fuel, ATC should co-ordinate with the flight crew:&lt;br&gt;&#xA;  (1) the route to be flown which, if possible, should be clear of cities and towns, preferably over water and away from areas where thunderstorms have been reported or are expected;&#xA;  (2) the level to be used;&#xA;  (3) the estimated duration of the fuel dumping; and&#xA;  (4) the frequency to be monitored whilst the aircraft is dumping fuel.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;13.3 Controllers are to recommend to flight crew that jettisoning of fuel should be carried out above 10,000 feet agl. Exceptionally, if fuel dumping at this level, or over water, is operationally impracticable or inconsistent with safety, fuel may be jettisoned above 7000 feet agl in winter and above 4000 feet agl in summer. For fuel to be jettisoned below these levels the situation must be unavoidable.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;13.4 A vertical separation of at least 1000 feet between aircraft should be maintained.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;13.5 Adjacent ATC units and control sectors should be informed of the fuel dumping taking place, including co-ordination with units providing services outside controlled airspace where the aircraft’s track is near to the boundary of controlled airspace (both laterally and vertically).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-10-01T13:31:20.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21484" PostTypeId="2" ParentId="21414" CreationDate="2015-10-01T13:58:24.493" Score="8" Body="&lt;p&gt;The problem is you're holding the aircraft with your hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine a windmill. It has no power at all, it spins freely. What happens when wind is blowing at it? It turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now imagine a propeller with no power connected to it, so it acts like a windmill. If wind is blowing at it, it will turn just the same. Why? Because a propeller pushes wind backward when it turns. When it is facing a headwind, the propeller &lt;em&gt;wants&lt;/em&gt; to turn such that it is pushing air at the same speed as the arriving air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your case, I suppose the fan is blowing air at a faster speed, compared to the propeller is pushing air on its motor. Say the motor pushes air backward at 1 m/s. The fan blows air at 2 m/s. That's why it spins faster with the fan on.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;But that's only true as long as you're holding the aircraft with your hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight, nothing is holding the aircraft at a constant ground speed. For example, assume in a no wind condition, an aircraft is flying at 80 knots. Suddenly it encounters a 10 knots headwind, and continues to fly into this headwind for the remainder of the flight. What happens?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the moment of encountering the headwind, the airspeed indicator in the cockpit &lt;em&gt;jumps&lt;/em&gt; from 80 to 90. The propeller rpm will also suddenly jump to a higher value. But that is not going to last. The aircraft is getting pushed backward by the wind, the airspeed is going to slowly drop back to 80. &lt;strong&gt;&lt;em&gt;There is not enough power to keep the propeller at the higher rpm which pushes air at 90, it can only to 80.&lt;/em&gt;&lt;/strong&gt; After a while, it is flying at 80 knots relative to the air, and 70 knots relative to the ground.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-10-01T13:58:24.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21485" PostTypeId="1" AcceptedAnswerId="31255" CreationDate="2015-10-01T14:29:48.527" Score="1" ViewCount="745" Body="&lt;p&gt;A way to reduce the pressure drag of bluff bodies is to apply a tapering of the tail (so called boat tailing)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know some (extreme) examples of this method of drag reduction applied to cars:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/wZIzT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wZIzT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wired.com/images_blogs/autopia/2009/12/boat-tail-geo-metro.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I know that this a feature of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Very-low-drag_bullet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Very low drag bullet&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gX1my.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gX1my.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Very-low-drag_bullet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I was wondering if there are any aerospace applications?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2016-09-04T21:26:04.833" Title="Are there any aerospace examples of applying a boat tail?" Tags="&lt;drag&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21486" PostTypeId="2" ParentId="21485" CreationDate="2015-10-01T14:40:14.583" Score="2" Body="&lt;p&gt;Almost all plane designs are made in wind tunnels and have a tapering empennage. Some notable exceptions which only taper in one dimension are rear-loading cargo planes like the C-130 and the Shorts Sky Van. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x2B4t.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x2B4t.jpg&quot; alt=&quot;C-130 empennage&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nhTz3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nhTz3.jpg&quot; alt=&quot;Shorts Sky Van rear door&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-10-01T15:34:56.253" LastActivityDate="2015-10-01T15:34:56.253" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21487" PostTypeId="2" ParentId="21485" CreationDate="2015-10-01T14:55:54.070" Score="5" Body="&lt;p&gt;This depends on the mission the plane is built to fit. Some planes need the cargo space so the tail is less tapered but most planes have at least some taper. Diamond Aircraft have very tapered tail sections &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s4gr3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s4gr3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.diamondaircraft.com/aircraft/da20/gallery.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the older GA designs like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_Aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper Seminole&lt;/a&gt; have a good deal of tail taper &#xA;&lt;a href=&quot;https://i.stack.imgur.com/Uc06j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uc06j.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_Aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger planes have some tail taper as well however sometimes there is less as there are often systems in the tail like the APU or there is storage space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cTrV9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cTrV9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://ourairports.com/aircraft/735/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-01T14:55:54.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21488" PostTypeId="2" ParentId="21404" CreationDate="2015-10-01T15:12:28.003" Score="0" Body="&lt;p&gt;Theoretically yes. In reality it depends.&lt;/p&gt;&#xA;&lt;h3&gt;Theoretically&lt;/h3&gt;&#xA;&lt;p&gt;We don't account for friction in the landing gear wheel bearings or between the treadmill and the wheels. This would mean that with the plane just sitting idle, if the treadmill moves the plane will remain still. You can try this by putting a toy car on a piece of paper. If you jerk the paper back and forth the car doesn't really move. The only reason the car moves is because of friction. If you eliminated friction in the wheels the car wouldn't move at all. We've now established that the moving runway has no influence over the plane. The pilot is free to start the engine and take off.&lt;/p&gt;&#xA;&lt;h3&gt;In reality&lt;/h3&gt;&#xA;&lt;p&gt;The real answer depends on the design and limits of the plane/treadmill:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In real life there is friction in the landing gear. There are limits to how fast the wheels can spin before they fail. But, there would also be a limit to how fast the treadmill could go.&lt;/li&gt;&#xA;&lt;li&gt;There are limits to how fast the treadmill and plane can accelerate and change directions. A pilot may be able to get the treadmill going in one direction then turn around and take off in the other.&lt;/li&gt;&#xA;&lt;li&gt;A very large treadmill moving at high speed would create wind. A strong enough wind can allow a plane to take off even though it's standing still. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/TlEKiSwttsc?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; The amount of wind generated would depend on exactly how smooth the surface is and how large it is.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7859" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-01T15:12:28.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21489" PostTypeId="2" ParentId="21414" CreationDate="2015-10-01T15:44:06.753" Score="0" Body="&lt;p&gt;Surprisingly, the answer is yes for geared engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With geared engines, the propeller has enough mechanical advantage to drive the gearbox (rather than the engine driving the gearbox). This can hurt the gearbox and the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Rotax engine employs a built-in 2.4:1 reduction gearbox. When descending, you are not supposed to reduce power, otherwise the propeller will push on the gearbox and the engine (rather than the engine turning the gearbox and then the prop). &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-10-01T15:44:06.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21490" PostTypeId="1" AcceptedAnswerId="21493" CreationDate="2015-10-01T16:05:37.337" Score="3" ViewCount="1808" Body="&lt;p&gt;An aircraft carrier is the largest type of warship and is used to transport, operate, and maintain military aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The staff which support aircraft in the carrier can be divided into 2 groups. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some &quot;variable&quot; staff are directly related to the aircraft operation like Pilots, the number of those staff is proportion to the number of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand the number of the &quot;fixed&quot; staff is fixed, regardless the number of aircraft, like Air Traffic Control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How many of the 2 different types of staffs are employed? To simplify the answer, please use the biggest Nimitz-class as example.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="5517" LastEditDate="2015-10-02T13:38:17.023" LastActivityDate="2015-10-02T13:38:17.023" Title="How many staff are needed to support aviation on an aircraft carrier?" Tags="&lt;aircraft-carrier&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21492" PostTypeId="1" CreationDate="2015-10-01T17:47:57.230" Score="4" ViewCount="568" Body="&lt;p&gt;I have a retired 747 pilot saying that a catastrophic jet engine failure could be restarted. I have little or no training, but I believe that the word &quot;catastrophic&quot; means that there is no recovery. My reference is the &lt;a href=&quot;http://www.smithsonianchannel.com/shows/747-the-jumbo-revolution/0/3407070&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;747: The Jumbo Revolution&lt;/em&gt;&lt;/a&gt; documentary which is on youtube.com and cable TV.&lt;/p&gt;&#xA;" OwnerUserId="11514" LastEditorUserId="62" LastEditDate="2015-10-01T17:59:18.413" LastActivityDate="2015-10-01T18:41:43.367" Title="Can a jet engine be restarted after a catastrophic failure?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-10-01T20:48:28.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="21493" PostTypeId="2" ParentId="21490" CreationDate="2015-10-01T18:36:00.397" Score="8" Body="&lt;p&gt;The ship's complement for a Nimitz class carrier is 3200. That is the crew required to maintain ship operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A further 2480 crew comprise the Air Wing - everyone needed to perform duties directly associated with flying activities, including maintenance, ordnance handling, emergencies, etc. It's treated as a separate entity because any one of ten Air Wings could be embarked on a carrier at any given time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is a total crew of 5680.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find a breakdown of specific trades or ranks for either entity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Nimitz-class_aircraft_carrier&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the newer Gerald R. Ford class carriers make extensive use of automation, and so have several hundred fewer crew members in the ship's complement.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-01T18:42:27.450" LastActivityDate="2015-10-01T18:42:27.450" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21494" PostTypeId="2" ParentId="21492" CreationDate="2015-10-01T18:41:43.367" Score="14" Body="&lt;p&gt;I have no desire to dispute what a fellow retired 747 captain said, so I'm wondering if there was some miscommunication between you and the captain. &#xA;Or perhaps his definition of catastrophic is different than mine. My understanding of catastrophic would preclude any attempt to restart the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During my time on the 747 I had three engine failures. One simply quit during descent, and I had the flight engineer restart it. One we shut down when the oil pressure started dropping precipitously. There was no thought of trying to restart it as that could well have trashed the engine. Neither of these two shutdowns was catastrophic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, on one occasion, shortly after takeoff from Lima, Peru, the #1 engine failed with a loud report, shaking the entire airplane. We were told later that the boom had been heard throughout Lima. The tower reported fire flaring out of both the front and rear of the engine for a few seconds. &#xA;After dumping fuel and landing, an inspection of the engine showed a lot of re-solidified melted metal on the inside of the tail cone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That was a catastrophic failure.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-10-01T18:41:43.367" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21495" PostTypeId="2" ParentId="21293" CreationDate="2015-10-01T18:43:14.370" Score="5" Body="&lt;p&gt;There's one major difference between a coaxial helicopter and a conventional single main rotor -- single tail rotor helicopter during autorotation: yaw control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A conventional helicopter has a main rotor which produces a torque. The tail rotor thrust, applied at the end of the tail boom, provides a counter-acting &quot;anti-torque&quot; to keep the helicopter pointing when the pilot wants it.  As the pilot, when I change the collective pitch of the main rotor, to go into a climb or a descent, the torque required to drive the main rotor goes up or down, and the pilot counters by raising or lowering the tail rotor collective to change the tail rotor thrust to match.  Additionally, if I want to yaw the nose to the left or right, I can use the pedals to raise or lower the tail rotor thrust in order to temporarily upset the balance between the main and tail rotor torques and steer the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, consider how yaw control works for a coaxial helicopter.  The torque of the upper rotor is now counter-balanced by the torque of the lower rotor.  To yaw the helicopter, the pedal inputs are set up to upset the balance of torques by raising the torque on one rotor (by increasing the collective) and lowering it on the other (decreasing collective), while maintaining the same thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, when I increase my rate of descent to autorotation, the engines are no longer providing torque to drive the main rotor--the rotor is being driven by the relative wind.  In a conventional helicopter, the tail rotor is still being driven by torque transmitted from the main rotor through the drive shafts--so while there's no main rotor torque to balance, I can still use the pedals to change the tail rotor thrust and control my yaw.  However, in a coaxial helicopter, when the  torque on the rotors is low, differential collective does not have very much control authority: depending on the collective setting, pedal inputs can have a weak effect, no effect, or most surprisingly, a negative effect!  To counter-act this, most coaxial helicopters have very large vertical fins to provide good low-speed directional stability and many have rudders to augment control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, here's a picture showing the empennage of the Kamov Ka-25 (from &lt;a href=&quot;http://www.aviastar.org/helicopters_eng/ka-25.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;aviastar.org&lt;/a&gt;).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/p2nhu.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p2nhu.gif&quot; alt=&quot;Kamov Ka-25 via aviastar.org&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More modern machines also have control systems that reverse the effect of pedal inputs on differential collective at the very low collective stick settings where control reversal can occur.  Flight manuals for coaxial helicopters advise against reducing forward speed too quickly during autorotation, since the directional stability is provided primarily by the body and tail.&lt;/p&gt;&#xA;" OwnerUserId="9015" LastActivityDate="2015-10-01T18:43:14.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21496" PostTypeId="2" ParentId="21466" CreationDate="2015-10-01T18:56:39.877" Score="7" Body="&lt;p&gt;The exact number on an EGT gauge is usually meaningless: The Alcor EGT gauge you'll find on many aircraft has no temperature markings on it - just 25-degree divisions, and a yellow &quot;reference pointer&quot; which the pilot sets to the maximum observed EGT:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Q01D1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q01D1m.jpg&quot; alt=&quot;Alcor EGT gauge&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The notable exception to this is turbocharged engines which have a Turbine Inlet Temperature (TIT) limit to protect the turbocharger. For engines with exhaust gas / turbine inlet temperature limits these limits will be specified in the aircraft's Pilot Operating Handbook, and usually marked with green/yellow/red arcs on the relevant gauges.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Exhaust Gas Temperature (EGT) provides pilots a way of monitoring the fuel/air mixture in the engine. It uses the stoichiometric mixture (where Fuel and Air are perfectly balanced so that there is no unburned fuel and no unburned oxygen at the end of the combustion event) as a reference: At this mixture the EGT is at its hottest (&quot;Peak EGT&quot;). Making the mixture richer or leaner will reduce the EGT, and all other mixture settings are described in terms of &quot;Degrees &lt;em&gt;Rich of Peak&lt;/em&gt;&quot; or &quot;Degrees &lt;em&gt;Lean of Peak&lt;/em&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Refer to the handy chart from Lycoming below for the remainder of this discussion:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/tJAao.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tJAao.png&quot; alt=&quot;EGT/CHT/Power/Fuel Consumption Chart - Lycoming O-360&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;EGT and Mixture&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;When we talk about mixture in piston aircraft engines we're generally interested in one of two things: &lt;strong&gt;&lt;em&gt;Best Economy&lt;/em&gt;&lt;/strong&gt; - getting the most power from the engine for the least amount of fuel, or &lt;strong&gt;&lt;em&gt;Best Power&lt;/em&gt;&lt;/strong&gt; - Getting the most power from the engine regardless of fuel burn.  We're also interested in something called &lt;em&gt;Detonation Margin&lt;/em&gt;, which in simple terms means &quot;how likely is this mixture to explode rather than burn nicely?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see on the Lycoming chart above the EGT provides us a way of finding those mixtures.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Best Economy Mixture&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &quot;Best Economy&quot; range begins at peak EGT, and continues on the lean side until the engine won't run smoothly anymore (usually the limit is about 100-150 degrees &lt;em&gt;Lean of Peak&lt;/em&gt;).&lt;br&gt;&#xA;Operating the engine at Best Economy mixture provides the most power for the least amount of fuel, and thus the longest endurance. It comes at the cost of a reduced detonation margin on the fuel/air mixture - operating at high power settings with a best economy mixture increases the chance of detonation.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most aircraft/engine manufacturers recommend Best Economy mixture for power settings below 75%, in part to reduce the risk of detonation. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;The Red Box - Where you &lt;em&gt;don't&lt;/em&gt; want to run your engine.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The area of the chart from peak EGT to about 100 degrees &lt;em&gt;Rich of Peak&lt;/em&gt; is often referred to as &quot;The Red Box&quot; -- in this range the fuel/air mixture has a low detonation margin, and the combustion event is producing the most internal stress on the engine components (cylinders, pistons).&lt;br&gt;&#xA;As you can see from the Lycoming chart the Cylinder Head Temperature (CHT) peaks in this range, and there is a risk of exceeding the CHT limits and seriously damaging your engine by operating in this range for extended periods of time, particularly at high power settings.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Best Power Mixture&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;From approximately 100 degrees &lt;em&gt;Rich of Peak&lt;/em&gt; to 200 degrees &lt;em&gt;Rich of Peak&lt;/em&gt; is the &quot;best power&quot; range - in this mixture range you can safely run the engine at high power settings (from 75% of rated power to full rated power) with limited risk of detonation. The engine is producing the most power it can in this range, which is useful if you need to climb over an obstacle in your flight path.&lt;br&gt;&#xA;For simple aircraft with fixed-pitch propellers the &quot;Best Power&quot; mixture can also be found by adjusting the mixture to obtain maximum RPM for a given throttle setting.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Operating in the &quot;Best Power&quot; range is not without risks - in particular, detonation is still possible at high power settings. The same Lycoming manual that I pulled the chart above from advises monitoring CHTs when using Best Power mixture settings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Less Interesting Mixtures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are two ranges on the chart I did not discuss above - they are what I call the &quot;Less Interesting Mixures&quot;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Leaner than Best Economy&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;As you continue to lean the engine past the &quot;Best Economy&quot; range you will notice a sharp drop-off in power. This drop is so precipitous that you will no longer be saving fuel as you leave the Best Economy range: You will be burning more fuel per unit of horsepower produced than you were in the economy range.&lt;br&gt;&#xA;Eventually the engine will run rough as the mixture becomes too lean to burn, and at the very extreme end the engine will quit, starved of fuel.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Richer than Best Power&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;Mixtures richer than Best Power don't produce the same precipitous drop in horsepower, but they consume &lt;em&gt;substantially&lt;/em&gt; more fuel per unit of horsepower produced. They also have other negative side effects, like producing black sooty exhaust that will get all over the belly of the aircraft.&lt;br&gt;&#xA;As the mixture gets richer it will eventually become too rich to burn, and the engine will begin to run rough as it did being leaned. At the far extreme the engine will become flooded, and cease to run.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Recommended Reading / Viewing&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Your engine manufacturer's operating instructions&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.avweb.com/features_old/pelicans-perch-18mixture-magic/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mixture Magic (John Deakin)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.avweb.com/ownership/the-savvy-aviator-59-egt-cht-and-leaning/&quot; rel=&quot;nofollow noreferrer&quot;&gt;EGT, CHT, and Leaning (Mike Busch)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eaavideo.org/video.aspx?v=2274677932001&quot; rel=&quot;nofollow noreferrer&quot;&gt;Leaning Basics (EAA/Mike Busch)&lt;/a&gt; (video)  &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eaavideo.org/video.aspx?v=2534345030001&quot; rel=&quot;nofollow noreferrer&quot;&gt;Leaning: The Advanced Class (EAA/Mike Busch)&lt;/a&gt; (video)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="19560" LastEditDate="2020-06-09T11:54:21.230" LastActivityDate="2020-06-09T11:54:21.230" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="21498" PostTypeId="2" ParentId="104" CreationDate="2015-10-01T19:39:20.007" Score="6" Body="&lt;p&gt;The FAA has recently come out with an InFO 15012 describing in detail what constitutes a loggable approach.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2015/InFO15012.pdf&quot;&gt;Logging Instrument Approach Procedures&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;h2&gt;Portions of InFo 15012&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Discussion: Section 61.57(c)(1-5) permits a pilot to use one of four&#xA;  methods to conduct and then log IAPs:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Actual instrument flight conditions flown in an aircraft;&lt;/li&gt;&#xA;  &lt;li&gt;Simulated instrument flight conditions, using a view-limiting device, flown in an aircraft with a safety pilot;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Simulated instrument flight conditions conducted in any FAA approved:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Flight Simulator/Full Flight Simulator (FFS), Flight Training Device (FTD), or Aviation Training Device (ATD),&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;A combination of methods 1 through 3 as prescribed by § 61.57(c)(4), or (5).&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;hr&gt;&#xA;  &#xA;  &lt;p&gt;A pilot may log an IAP for currency or training when the pilot&#xA;  accomplishes the IAP in accordance with the following conditions:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must operate that&#xA;  aircraft or authorized training device solely by reference to&#xA;  instruments [§ 61.51(g)(1)];&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, flight simulator, flight training device, or aviation training device, the pilot must be established on&#xA;  each required segment of the IAP to the minimum descent altitude (MDA)&#xA;  or decision altitude/decision height (DA/DH);&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft simulating instrument flight conditions, a flight simulator, a flight training device, or an&#xA;  aviation training device, the simulated instrument meteorological&#xA;  conditions (IMC) must continue to MDA or DA/DH; and&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft, the flight must be conducted under actual or simulated instrument flight conditions [§ 61.51(g)(1)].&lt;/li&gt;&#xA;  &lt;li&gt;When conducted in an aircraft maneuvering in IMC, and the aircraft transitions from IMC to visual flight conditions on the final approach&#xA;  segment of the IAP prior to or upon reaching MDA or DA/DH.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2015-10-01T19:43:53.440" LastActivityDate="2015-10-01T19:43:53.440" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21499" PostTypeId="1" CreationDate="2015-10-01T19:43:21.083" Score="3" ViewCount="5805" Body="&lt;p&gt;What phenomenon causes aerodynamic tail-down force? Why will there be more downforce on the tail when an aircraft picks up speed? What happens if the aircraft goes too slow - does this means less downforce on the tail? Do the center of lift and center of gravity play any part in determining the downforce on the tail?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="62" LastEditDate="2015-10-02T00:53:27.510" LastActivityDate="2017-12-23T15:40:11.957" Title="What causes tail-down force?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21500" PostTypeId="1" CreationDate="2015-10-01T20:41:25.477" Score="5" ViewCount="1233" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_38&quot; rel=&quot;nofollow&quot;&gt;British Airways Flight 38&lt;/a&gt; experienced a loss of power during approach to Heathrow and ended up crashing 270m short of the runway.&#xA;The aircraft was on glideslope when it lost power. The name &quot;glideslope&quot; suggests it should be able to glide to a safe landing. So why didn't it?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;Suppose a commercial aircraft (e.g. 7X7, A3X0) lost all engines (say, due to birdstrike) shortly before landing. How likely would a safe landing on the planned runway be?&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It would make sense for the approach angle to be such that a safe landing is very likely. So if not, why not?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: To clarify (due to @rbp's comment): I want to know how far is the typical approach angle from being able to glide in? And why is the approach angle not chosen so that gliding is possible?&lt;/p&gt;&#xA;" OwnerUserId="11521" LastEditorUserId="11521" LastEditDate="2015-10-01T21:01:23.560" LastActivityDate="2015-10-02T13:28:23.867" Title="Can a plane land safely if it loses power during approach?" Tags="&lt;landing&gt;&lt;engine-failure&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21501" PostTypeId="2" ParentId="21499" CreationDate="2015-10-01T20:42:37.040" Score="1" Body="&lt;p&gt;On a conventional wing and tail configuration the center of lift is normally behind the center of gravity. This causes a pitch-down force, which is counteracted with the stabilizer's downward lift.&#xA;As speed increases, the wing produces more lift, thus more tail-down -force is required to maintain attitude.&#xA;On a rear-wing configuration the same is accomplished with a canard. The only difference is that the canard provides upward lift and so it adds to the total lift, contrary to a conventional tail just increasing drag.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-10-01T20:42:37.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21502" PostTypeId="2" ParentId="21499" CreationDate="2015-10-01T20:48:40.867" Score="0" Body="&lt;p&gt;The tail is a lifting surface just like the wings. Downforce is just the phenomenon of lift directed in the opposite direction. You can also see examples of downforce in things like the spoilers on a Formula 1 car. Going faster produces more lift and so more downforce.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's unique about the tail is that it can be affected by the downwash of the wings themselves which comes into play when looking at design choices like a T-tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Zooming out more broadly, the reason you want downforce is longitudinal stability. On some planes and in certain configurations the tail produces positive lift instead of downforce, all in the name of balancing the plane, though those designs tend to be harder to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may notice that the tail is usually much smaller than the wings. This allows for better longitudinal stability as the tail experiences larger relative changes in lift (downforce) compared to the wings which provides a negative feedback loop that brings the plane back to equilibrium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The location of the center of gravity relative to the center of lift matters because it produces a certain pitching moment that then needs to be counteracted by the force produced by the tail.&lt;/p&gt;&#xA;" OwnerUserId="11520" LastEditorUserId="11520" LastEditDate="2015-10-01T21:50:11.443" LastActivityDate="2015-10-01T21:50:11.443" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21503" PostTypeId="2" ParentId="21470" CreationDate="2015-10-01T20:51:11.773" Score="3" Body="&lt;p&gt;I haven't heard of any regulations about the length of the safety demo, just the content, which is pretty much as you described. However it's in the airline's interest to keep it as short as possible. The aircraft cannot take-off before the chief of cabin notifies the cockpit that the cabin is ready for take-off. The cabin is ready after all passengers are on their seats, safety demo completed, galleys secured and hand luggage stowed away.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-10-01T20:51:11.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21504" PostTypeId="2" ParentId="21500" CreationDate="2015-10-01T20:55:43.307" Score="3" Body="&lt;p&gt;On &quot;glideslope&quot; doesn't mean the aircraft can glide to a safe landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The glideslope is a 3-degree approach path, which is considered the &quot;normal&quot; landing path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders, which don't have engines, and many warbirds are flown such that they can glide to the runway from any point on the approach.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-10-01T20:55:43.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21505" PostTypeId="2" ParentId="21500" CreationDate="2015-10-01T21:07:16.010" Score="1" Body="&lt;p&gt;The approach path of an airplane making powered vs unpowered (gliding) approach would be very different - normal powered approach is around 3 degrees steep, unpowered approach will be much steeper.  While a small piston engine plane can perform power-off approach and still be agile enough to power up on short final for a go-around, a big commercial jet can't do it.  Furthermore, the chance of a complete engine failure in a multiengine airplane is fairly small.  So it is much safer for multiengine aircraft to execute fairly shallow powered approaches (3 deg).&lt;/p&gt;&#xA;" OwnerUserId="11456" LastEditorUserId="11456" LastEditDate="2015-10-01T21:13:04.363" LastActivityDate="2015-10-01T21:13:04.363" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21506" PostTypeId="2" ParentId="21375" CreationDate="2015-10-01T21:54:56.597" Score="3" Body="&lt;p&gt;To compare:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_4.pdf&quot; rel=&quot;nofollow&quot;&gt;747-400&lt;/a&gt; gear is 1.91-2.47 meters tall, depending on model and loading, so it sits slightly higher in general than the 747-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A320_May2014.pdf&quot; rel=&quot;nofollow&quot;&gt;A320&lt;/a&gt; (including neo) sits at 1.79-1.95 meters, so basically the same as the 747-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot; rel=&quot;nofollow&quot;&gt;737&lt;/a&gt; sits lower than the other two models, at 1.1 meters for the classic models, and 1.2-1.4 meters for the NG models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is interesting to note the similarities and differences. Designers want to keep the gear as short as possible to save weight, as well as to make maintenance or emergency evacuation easier. The gear still needs to be high enough to allow the aircraft to rotate on takeoff without striking the tail. Other aspects can be adjusted to maintain clearance for the engines. So even though the A320 and 747 are very different in size, they have the same gear height.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 is different when it comes to gear length. The original 737 had engines that required much less height to clear the ground. The new engines on the classics and NG series needed more room, resulting in longer landing gear. However, the gear is still shorter than the other examples.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-10-01T21:54:56.597" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21508" PostTypeId="2" ParentId="21500" CreationDate="2015-10-01T23:42:32.493" Score="1" Body="&lt;p&gt;I think a main difference between piston engines and jet engines is the time it takes for the jet engine to spool up.  Where a piston engine has near instantaneous power; a jet engine will take several seconds to produce full power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is this reason why a jet pilot prefers to have power in the mid range during an approach somthat if they have to perform a go-around the time it takes to spool up and produce full power is reduced.  If the angle was such that the engines were at glide power during the approach a go-around would be a much more dangerous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the glideslope were increased so its engine can be at idle during the dedcent, any failure that would cause the jet to land with less than full drag will inherently cause the jet to increase speed during the descent.  The pilots would be forced to use a shallower descent angle to keep the speed under control.  If the approach wasn't designed for a shallower approach it could cause the jet to get dangerously to terrain.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-01T23:42:32.493" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21509" PostTypeId="2" ParentId="21500" CreationDate="2015-10-01T23:45:36.380" Score="3" Body="&lt;p&gt;This varies for every plane and in every situation. Generally speaking every plane has a &quot;Best Glide&quot; speed. This is the speed through the air at which you will gain the largest ground cover for a given vertical distance traveled. Most planes have a published glide chart like this one for a &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow noreferrer&quot;&gt;PA-28&lt;/a&gt;. The published glide ratio is usually achieved at the best glide speed or or specified rates may be achived at a specific air speed.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ToQUx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ToQUx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.pprune.org/private-flying/415672-glide-speeds-pa28r-versions.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see that this chart is specifically for 0 flaps, gear up, and 0 wind. All of those factors will decrease the distance you can travel while gliding as they increase drag. The very need of flaps is to increase the approach angle without increasing the speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The glide slope is generally around 3 Degrees but more precisely it is at an angle which guarantees clearance from all obstructions that may be in the approach path so it may actually vary. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are on slope and you plane has a glide ratio that allows for an at or better angle you may be able to make the runway. However the term does not imply that it allows you to &quot;glide&quot; to a landing should the plane lose power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of all that you will generally be landing into the wind, with that in mind if you have a strong head wind down the runway and you lose power you may may fall short due to an altered ground speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a nice &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/1621604/&quot; rel=&quot;nofollow noreferrer&quot;&gt;debate on it here&lt;/a&gt; but smaller planes like a &lt;a href=&quot;http://www.diamondaircraft.com/media/27/DA20%20Australian%20Aviation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Diamond DA-20 has a glide ratio of 11:1&lt;/a&gt; and a Cessna 172 has a glide ratio of 9:1 if memory serves. Various places around the internet seem to say bigger jets have in the 17:1 - 20:1 ratio range so they may even glide better than smaller planes. One difference with bigger jets is that they have larger speed ranges and if best glide speed is at 300KT the plane may be well below that on short final and by the time it pitches down to gain the speed it will be on the ground. Compare this to a Piper Warrior that has a 73KT best glide speed and a 70KT approach speed (sometimes I even come in at 75KT on a long runway in a warrior). It can be far easier to come to best glide in a smaller plane than a big jet. Keep in mind that on final approach you will have flaps down, gear down, and possibly slats down if your plane has them. That will greatly change what this chart would look like.  I These charts are mainly published so you know how far you can go if you lose an engine in flight. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-02T13:28:23.867" LastActivityDate="2015-10-02T13:28:23.867" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21510" PostTypeId="2" ParentId="21397" CreationDate="2015-10-02T00:21:49.163" Score="0" Body="&lt;p&gt;While the above are certainly good reasons how this came to be, today the answer is very simple and is the same for almost all commercial aviation questions starting with &quot;why&quot;: because there is an FAA regulation and changing an FAA regulation needs monumental effort and thus needs an extremely compelling reason first.&lt;/p&gt;&#xA;" OwnerUserId="11524" LastActivityDate="2015-10-02T00:21:49.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21511" PostTypeId="1" AcceptedAnswerId="21515" CreationDate="2015-10-02T00:26:04.877" Score="8" ViewCount="615" Body="&lt;p&gt;On a wing, a wing tip vortex is unavoidable no matter what configuration you use, but does a vertical stabilizer form a wing tip vortex? I noticed this picture and saw two vortices coming off of the vertical stabilizers, so was this a result of moving the rudder or does the vertical stabilizer generate lift just like an aircraft wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bAWHz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bAWHz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://media.dma.mil/2005/May/13/2000582877/-1/-1/0/050512-F-2295B-280.JPG&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="62" LastEditDate="2015-10-02T00:49:35.153" LastActivityDate="2015-10-02T02:14:58.587" Title="Do vertical stabilizers create vortices like wingtips do?" Tags="&lt;aerodynamics&gt;&lt;wing-tip-vortex&gt;&lt;vertical-stabilizer&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21513" PostTypeId="1" AcceptedAnswerId="21514" CreationDate="2015-10-02T00:50:28.430" Score="19" ViewCount="10809" Body="&lt;p&gt;This is a JetBlue A320:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/443sN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/443sN.jpg&quot; alt=&quot;JetBlue A320 with items on fuselage top/bottom indicated&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always wondered what these are for, but could never find the answer. I'm guessing a few of them are for receiving information from satellites. &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="14897" LastEditDate="2020-04-18T12:21:34.497" LastActivityDate="2020-04-18T12:21:34.497" Title="What are these antenna-like protrusions for on an airliner?" Tags="&lt;airliner&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21514" PostTypeId="2" ParentId="21513" CreationDate="2015-10-02T01:40:27.030" Score="31" Body="&lt;p&gt;They are the various communication and navigation antennas of the aircraft. This figure shows the location of antennas in A320, the type of aircraft in picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jOVFC.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jOVFC.png&quot; alt=&quot;A320 antenna location&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: pprune.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some antenna (the ones with *) are optional and the installation varies with customer. The communication antenna location in A320 can be seen in this image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YLBBk.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YLBBk.png&quot; alt=&quot;Comm antenna&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airbus training course from airbus.altervista.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the navigation antenna location in this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0MYqO.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0MYqO.png&quot; alt=&quot;Nav antenna&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airbus training course from airbus.altervista.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dome (2 in the picture) is the radome for the &lt;a href=&quot;http://www.nycaviation.com/2013/09/a320-finally-certified-for-livetvs-wi-fi-coming-soon-to-jetblue/&quot; rel=&quot;noreferrer&quot;&gt;wi-fi system introduced by Jetblue&lt;/a&gt;, dubbed Fly-Fi.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QeZgW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QeZgW.jpg&quot; alt=&quot;Wi Fi radome&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: nycaviation.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;1,3,4 - VHF&lt;/li&gt;&#xA;&lt;li&gt;2 - Wifi&lt;/li&gt;&#xA;&lt;li&gt;6 - ELT&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-02T05:12:02.837" LastActivityDate="2015-10-02T05:12:02.837" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="21515" PostTypeId="2" ParentId="21511" CreationDate="2015-10-02T01:54:07.320" Score="5" Body="&lt;p&gt;In general, the vertical stabilizer and rudder create a symmetric airfoil. As there is no pressure difference between the two surfaces of the vertical stabilizer, vortices doesn't form, unlike the wing, which is designed to produce lift at normal angles of attack (it is usually cambered, producing lift at zero angle of attack).&lt;/p&gt;&#xA;&lt;p&gt;You're correct that the vortices are generated due to the movement of rudder. Usually, vertical stabilizer doesn't create vortices unless rudder is deflected.&lt;/p&gt;&#xA;&lt;p&gt;Note: Though I can't be sure, I think the F-22 is braking (the F-22 does not have a dedicated surface for braking like F-15 and uses the normal flight control surfaces). A similar thing happens in the following figure&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sNHMY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sNHMY.jpg&quot; alt=&quot;F 22 braking&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source: f-16.net&lt;/p&gt;&#xA;&lt;p&gt;Only one F-22 (second from top) is using its control surfaces, probably for braking, resulting in vortices from the vertical stabilizer.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-02T02:14:58.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21516" PostTypeId="2" ParentId="21404" CreationDate="2015-10-02T03:47:58.773" Score="0" Body="&lt;p&gt;I had a thought here:  If we are considering a perfect treadmill and perfect wheels/bearings on the plane it doesn't take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane starts to roll.  The treadmill matches the wheel's speed, but this simply spins the wheels faster--so long as the plane is rolling the treadmill is in a never-ending race against the wheel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since we are looking at a perfect system this proceeds without limit and infinitely fast--the treadmill (and wheel's outer edge) is going to be approaching lightspeed.  The mass grows without limit, the plane is too heavy to take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the real world with imperfect systems something has to give.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1)  The wheels have a maximum speed.  Exceed that by too much and your landing gear explodes.  The plane pancakes onto the treadmill, the friction is too great for it to overcome, it's tossed backwards and then stops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2)  The treadmill has a maximum speed.  If the wheels can survive takeoff velocity plus this speed the plane takes off, else #1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3)  The treadmill has a finite acceleration rate.  The plane very well might take off before the treadmill has built up serious velocity.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-10-02T03:47:58.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21517" PostTypeId="2" ParentId="21426" CreationDate="2015-10-02T04:22:20.710" Score="0" Body="&lt;p&gt;Yeah, precision would be the deal breaker.  This is why excavators, for instance, use hydraulics because you can deliver a lot of power with very minute movements.  Good operators could pick up a quarter then knock over a tree.  So while in flight, control surfaces are subject to enormous pounds of air pressure but must move only a few inches and with a within a rapid response time.  A liquid is going to have the viscosity for more &quot;fluid&quot; movements which is more susceptible to instantaneous responses.  You'll see pneumatic systems a lot in plants for valve applications which will be fully open or fully closed.  Because air is so light is just can't deliver the same power and precision.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides fly by wire makes any of this talk rather obsolete.  You can get all the electrical power you need to extremely high HP/torque actuators that will deliver just as much force with even more precision and greater response time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure but I wouldn't doubt the wheel braking system might be pneumatic like over-the-road 18 wheelers.  Otherwise the only pressurized air you're ever going to see on a airliner will be cabin pressure and oxygen delivery.&lt;/p&gt;&#xA;" OwnerUserId="11528" LastActivityDate="2015-10-02T04:22:20.710" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21518" PostTypeId="1" AcceptedAnswerId="21536" CreationDate="2015-10-02T06:10:53.713" Score="15" ViewCount="2651" Body="&lt;p&gt;Espresso makers work by bringing water to a certain temperature (typically 198-202°F / 92-95°C), and then extract it at a high pressure (~9 bar). Given that the FAA requires that cabins are pressurized to ~7,500 ft, this results in a few problems I can see.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The pressure differential between the boiler and the cabin would be very large. I fear that this would result in the espresso machine being compromised.&lt;/li&gt;&#xA;&lt;li&gt;Water would boil at a much lower temperature (198°F / 92°C) resulting in the machinery not working correctly. &lt;/li&gt;&#xA;&lt;li&gt;A sudden depressurization of the vessel could certainly result in a dangerous pressure differential resulting in explosive decompression. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Although, a Boeing 787 has a higher pressure cabin, in a typical airplane, could you safely brew espresso? Are there any FAA, or other safety regulations preventing you from doing so? &lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="19" LastEditDate="2015-10-02T13:00:18.663" LastActivityDate="2015-10-03T13:29:21.370" Title="Can espresso be made at cruising altitude?" Tags="&lt;safety&gt;" AnswerCount="4" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21519" PostTypeId="2" ParentId="21500" CreationDate="2015-10-02T06:38:49.173" Score="5" Body="&lt;p&gt;A standard “glide-slope” is 3–3.3°. 3° is 5.2% or 1:19, 3.3° is 5.8% or ~1:17.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A modern airliner will have lift to drag ratio between 17:1 and 20:1 in clean configuration and at best glide speed, which is usually somewhere in range 220–250 knots indicated, possibly even a bit more depending on weight. So it would be just barely able to follow the glide-slope if it was configured for best glide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on final approach it will at least need gear down and that increases the drag considerably. It will also already be slower than the best glide speed and have some flaps deployed and retracting them and accelerating to the best glide speed will take some altitude. Therefore if all engines quit on final, the aircraft is definitely landing short of the intended point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small aircraft I've read advice that if the runway is long enough, you should normally plan to use the &lt;a href=&quot;http://www.av8n.com/how/htm/landing.html#sec-touchdown-point&quot; rel=&quot;noreferrer&quot;&gt;middle part of the runway&lt;/a&gt; exactly so that you have a margin when engine quits on short final, accompanied with account of incident where it proved useful right there and &lt;a href=&quot;http://www.av8n.com/how/htm/emerge.html#sec-configure-glide&quot; rel=&quot;noreferrer&quot;&gt;another in the next chapter&lt;/a&gt;. However airliners need more runway, so they can't afford leaving much reserve on the near end, plus they usually follow the ILS or at least PAPI and those lead to fixed spot 1000 ft past threshold.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-10-02T06:38:49.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21520" PostTypeId="2" ParentId="21518" CreationDate="2015-10-02T06:43:52.990" Score="8" Body="&lt;p&gt;The high pressure in the modern &lt;a href=&quot;https://en.wikipedia.org/wiki/Espresso_machine&quot;&gt;espresso machine&lt;/a&gt; is not created by the highly pressurized boiler. It is created by the pump pushing hot water under pressure. Many models do heave the boiler to foam the milk, for instance, but this is not required for making the coffee itself. This pump can even be hand operated. &lt;a href=&quot;https://www.kickstarter.com/projects/uniterra-nomad/nomadtm-the-go-everywhere-espresso-machinetm/description&quot;&gt;Some&lt;/a&gt; machines even need no electricity, just a hot water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If exactly boiling water is required, it can be kept only slightly pressurized. However water under cabin pressure is also quite hot; maybe it is enough just to add more coffee or increase the brewing duration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not competent to issue &quot;airworthiness certificates&quot; for espresso machines, but as a passenger I can say that the idea may be worth exploring; coffee as it is served now is never the best part of the flight experience. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2015-10-02T06:55:36.080" LastActivityDate="2015-10-02T06:55:36.080" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21522" PostTypeId="1" CreationDate="2015-10-02T07:27:10.487" Score="9" ViewCount="1551" Body="&lt;p&gt;Tiger Airways Singapore's IATA code is TR while Tiger Airways Australia's one is TT, but the ICAO code for both is TGW. I thought that the ICAO codes are meant to be unique from one airline to another, not the other way around. Is this the only case?&lt;/p&gt;&#xA;" OwnerUserId="11530" LastEditorUserId="62" LastEditDate="2015-12-03T19:10:29.020" LastActivityDate="2016-05-18T20:11:02.787" Title="Are airline ICAO codes unique?" Tags="&lt;airline-operations&gt;&lt;icao&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21523" PostTypeId="1" AcceptedAnswerId="21526" CreationDate="2015-10-02T08:00:21.563" Score="30" ViewCount="17369" Body="&lt;p&gt;Consider the &lt;a href=&quot;https://i.stack.imgur.com/gUuZL.jpg&quot; rel=&quot;noreferrer&quot;&gt;fuselage of an A300&lt;/a&gt;. I have noticed this not only with airliners, but also for private jets and turboprops: why is the fuselage circular-shaped? Why don't aircraft have square-shaped fuselage? Does it have to do with too much drag?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="849" LastEditDate="2015-10-02T18:26:00.377" LastActivityDate="2021-03-28T05:03:59.090" Title="Why is the fuselage on an airliner circular-shaped?" Tags="&lt;fuselage&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21524" PostTypeId="2" ParentId="21523" CreationDate="2015-10-02T08:07:28.240" Score="13" Body="&lt;p&gt;Drag has little to nothing to do with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary reason why the fuselage is circular (or &lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/601-700/awa628-A380-McGehee/21.jpg&quot;&gt;elliptical&lt;/a&gt;) shaped is that the cabin is pressurised.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that, mostly during cruise, the interior of the fuselage has an higher pressure than the outside atmosphere. The circular (or roughly circular) shape allow the fuselage to avoid blowing up like a baloon with minimal amount of material, minimizing the overall weight of the aircraft. A square fuselage would break apart at the corners due to &lt;a href=&quot;https://en.wikipedia.org/wiki/Stress_concentration&quot;&gt;stress concentration&lt;/a&gt;. A circular shape do not have corners were the tensile stress can concentrate.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-10-02T08:07:28.240" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21525" PostTypeId="2" ParentId="21523" CreationDate="2015-10-02T08:13:51.527" Score="40" Body="&lt;p&gt;If you pressurize any hollow structure, it will try to assume a round shape. If you want to create a lightweight pressure vessel, again a sphere will be the most efficient result, because there the stresses in the skin will be equal at every point. Blow up a party balloon if you are in doubt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A sphere is not the most efficient shape for aerodynamics, so fuselages are elongated spheres with a nice fairing at the end. If you make them cylindrical in the middle, you can build most bulkheads on the same jig and can interchange sections of the internal fairings. Plus, if you need a longer or shorter fuselage for the next version of the plane, you can easily add or remove sections - the parts will still fit after the modification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the fuselages of unpressurized aircraft don't follow this logic A &lt;a href=&quot;https://en.wikipedia.org/wiki/Short_SC.7_Skyvan&quot; rel=&quot;noreferrer&quot;&gt;Short Skyvan&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_228&quot; rel=&quot;noreferrer&quot;&gt;Dornier 228&lt;/a&gt; have fuselages with a rectangular cross section, so large cargo can fit in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, some fuselages are combinations of cylinders. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot; rel=&quot;noreferrer&quot;&gt;Boeing 377 Stratocruiser&lt;/a&gt; used the lower fuselage of the B-29 and had an upper, larger cylinder on top to give the passengers more room.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NyKDR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NyKDR.jpg&quot; alt=&quot;Boeing 377 cross section&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 377 cross section (picture &lt;a href=&quot;http://2.bp.blogspot.com/_eqb8qL2GKZc/S7JNujnPOSI/AAAAAAAADl0/iz9rQRjHNYc/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same reason, rocket stages are cylindrical, too. They also need to be aerodynamic, have to tolerate high internal pressure and need to be lightweight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-04T08:01:55.137" LastActivityDate="2015-10-04T08:01:55.137" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21526" PostTypeId="2" ParentId="21523" CreationDate="2015-10-02T08:42:10.727" Score="34" Body="&lt;p&gt;The fuselages are circular (or nearly circular) in shape for two &lt;a href=&quot;http://adg.stanford.edu/aa241/fuselayout/fusesection.html&quot; rel=&quot;noreferrer&quot;&gt;main reasons&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The main reason is that for a circular cross section, the pressure loads are resisted by tension, rather than by bending loads in non-circular sections. Also, the non-circular sections have stress concentrations when pressurized, which may lead to failure.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of a circular design, the flow will not separate under small (to moderate) angles of attack and in sideslip.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case of non-pressurized aircraft, the fuselages are dictated by volume constraints and are usually rectangular in shape as it is more efficient in space utilization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7gkD5.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7gkD5.gif&quot; alt=&quot;Commuter cabin cross sections&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of pressurized aircraft, the best option structurally is to have a circular fuselage, but in order to have a useful internal space, an elliptical or 'double bubble' design is used, with an outer circular section and divided internal sections, like the A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rVpNC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rVpNC.jpg&quot; alt=&quot;A380 fuselage cross section&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-10-02T18:20:59.853" LastActivityDate="2015-10-02T18:20:59.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21527" PostTypeId="2" ParentId="17485" CreationDate="2015-10-02T09:10:14.267" Score="3" Body="&lt;p&gt;According to this &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/f-22-stealth.htm&quot; rel=&quot;nofollow&quot;&gt;article&lt;/a&gt; and this &lt;a href=&quot;https://books.google.com/books?id=k8skNF7RZVkC&amp;amp;lpg=PA34&amp;amp;ots=9d8JbvLFce&amp;amp;dq=ceramic%20matrix%20ram%20wide-band%20structural%20RAM&amp;amp;pg=PA34#v=onepage&amp;amp;q=ceramic%20matrix%20ram%20wide-band%20structural%20RAM&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;book&lt;/a&gt;, they use a greater amount of wide-band structural RAM on the wing's edges, whereas they use a ceramic-matrix RAM on the exhaust nozzles. Not only is that the case, but the actual edges have proprietary material designed to be stronger, and have a different radar signature. Although, what you're seeing is probably a combination of the paint job as well as the material, considering the F-22's stealth is not only an aspect of radar, but also visibility. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the stealth of the F-22 comes from the physical shape of the F-22, and reducing its radar cross-section. There are also specialized materials that assist in obscuring its infrared signature. The topcoat, a type of paint, assists in reducing the infrared signature, especially. &lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="11423" LastEditDate="2015-10-06T21:13:25.730" LastActivityDate="2015-10-06T21:13:25.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21528" PostTypeId="2" ParentId="21523" CreationDate="2015-10-02T09:34:21.907" Score="20" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why don't [airliners] have square shaped fuselage?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YgFJm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YgFJm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Shorts Skyvan photo from &lt;a href=&quot;http://www.wingsovereurope.com/skyvan_light_transport.html&quot; rel=&quot;noreferrer&quot;&gt;Wings over Europe&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ec4v4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ec4v4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Shorts Skyvan diagram from &lt;a href=&quot;http://atallguy.com/Simple-Multi-View-Plans/S.html&quot; rel=&quot;noreferrer&quot;&gt;A Tall Guy&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airliners are pressurized. If you inflate a rubber balloon you'll notice that the most economical and strongest shape for a pressurized container is one with a circular cross-section. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll also notice, when you inflate an &lt;a href=&quot;http://www.origami-instructions.com/origami-water-balloon.html&quot; rel=&quot;noreferrer&quot;&gt;Origami water bomb&lt;/a&gt; (you should stop reading this and make an origami water bomb now), that the flat sides buckle and bulge - flat sheets are not good at resisting pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spherical airliners would have too many disadvantages but cylindrical ones have a good balance between strength, weight, drag and space-efficiency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see above, in some circumstances, aircraft manufacturers do beleieve that the advantages of a  rectangular cross-section are worthwhile.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-10-02T09:42:52.053" LastActivityDate="2015-10-02T09:42:52.053" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21529" PostTypeId="2" ParentId="21500" CreationDate="2015-10-02T10:22:28.417" Score="2" Body="&lt;p&gt;Many aircraft are able to do an unpowered glide at the 3$^\circ$ angle that the typical (ILS) glideslope is. However that requires the aircraft to be in clean configuration (no flaps, no gear) and at a speed well above landing speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft is configured for landing (flaps + gear down) it requires a fair amount of power to maintain on the glideslope. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It would make sense for the approach angle to be such that a safe&#xA;  landing is very likely. So if not, why not?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the glideslope was steep enough to support an unpowered approach, then there would no margin to slow down the aircraft if it were approaching fast (one can't apply less power). It becomes difficult to stabilize the aircraft before landing. Also turbine aircraft need to be above idle power during the approach to ensure a fast response in case of a missed approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of a steep approach at near idle power, additional drag would be required to slow down. Most aircraft can only provide this by extending the spoilers. Unfortunately this also reduces the lift produced by the wing, something which is usually avoided on approach. A few transport aircraft such as the BAe 146/ RJ70 / RJ85 / RJ100 and Fokker F70/F100 are equipped with air brakes. They aid in slowing down the aircraft on steep approaches without compromising the lift. Steep approach modifications to the Airbus A318 includes changes to the spoiler logic such that they will extend only to 30% to prevent loss of lift. Propeller aircraft usually have less difficulty with steep approaches since the propeller can be used as an effective air brake. For these reasons the diversity of aircraft at London City airport (glideslope 5.5$^\circ$) is limited to a few models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently there is an experiment running on Heathrow airport that features a increased glideslope (3.2$^\circ$ instead of 3$^\circ$) to reduce noise. Due to the steeper approach the aircraft require less power to maintain speed which relieves people living nearby of some noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This small increase in glideslope angle does not require special training for the flight crew or changes to aircraft but it may have a negative effect on the airport's capacity. Since the steeper slope reduces the deceleration capability of aircraft it might lead to an increase in go-arounds (e.g. because the aircraft's speed isn't stabilized at 1000ft, or the separation between successive aircraft is compromised).&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-10-02T10:22:28.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21530" PostTypeId="2" ParentId="21222" CreationDate="2015-10-02T10:36:33.823" Score="6" Body="&lt;p&gt;Development is in progress, just a matter of time:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oaa1B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oaa1B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://translate.google.com/translate?sl=de&amp;amp;tl=en&amp;amp;js=y&amp;amp;prev=_t&amp;amp;hl=de&amp;amp;ie=UTF-8&amp;amp;u=https%3A%2F%2Fwww.bundesregierung.de%2FContent%2FDE%2FArtikel%2F2015%2F06%2F2015-06-23-hubschrauber.html&amp;amp;edit-text=&quot; rel=&quot;nofollow noreferrer&quot;&gt;Helicopters are quieter (translation by Google)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11537" LastEditorUserId="3201" LastEditDate="2016-03-05T21:40:06.100" LastActivityDate="2016-03-05T21:40:06.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21531" PostTypeId="2" ParentId="21396" CreationDate="2015-10-02T10:44:16.497" Score="1" Body="&lt;p&gt;When I flew C-130 transporters in the RAF, we always carried a FAK and a 'Ground Engineer', but then the extra weight was of little consequence compared to the delay of the mission in some remote location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I now fly Business Jets, where there is significantly less room, less available (spare) payload weight, and certainly no-one qualified to make the repairs on board, so the only thing carried is a small set of wheel chocks, a couple of cans of oil and clamps for the trust-reversers.&lt;/p&gt;&#xA;" OwnerUserId="11538" LastEditorUserId="1467" LastEditDate="2015-10-02T11:02:48.053" LastActivityDate="2015-10-02T11:02:48.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21532" PostTypeId="1" AcceptedAnswerId="21533" CreationDate="2015-10-02T11:18:13.693" Score="15" ViewCount="9095" Body="&lt;p&gt;If a 777 ER has to immediately land after takeoff on a planned 14,594 km trip (in the case of a fire, e.g.), the landing will be executed with a very heavy aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are the major concerns of doing such a landing?&lt;/li&gt;&#xA;&lt;li&gt;What will, on average, be the consequences of this overweight landing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2448" LastActivityDate="2020-08-25T06:56:37.270" Title="What are the concerns and consequences of an overweight landing?" Tags="&lt;landing&gt;&lt;fuel&gt;&lt;weight&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21533" PostTypeId="2" ParentId="21532" CreationDate="2015-10-02T11:33:39.413" Score="20" Body="&lt;p&gt;Two things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/7889/how-much-force-does-a-747-land-with&quot;&gt;Loads on the landing gear&lt;/a&gt;. This can be alleviated by carefully touching down, but you never know what exactly will happen in the next landing, so better don't count on it to be smooth&lt;/li&gt;&#xA;&lt;li&gt;Deceleration distance: The higher mass requires a higher approach and touch down speed (higher by the square root of the mass ratio between your actual mass and the maximum certified landing mass). Now you have more mass &lt;strong&gt;and&lt;/strong&gt; more speed, but the landing strip and the airliner's brakes are still the same. The risk is that you overshoot the runway with an airplane full of fuel or that you overheat the brakes (which will result in their failure, and again an overshoot). Since the kinetic energy is proportional to mass times speed squared, the energy which needs to be absorbed by the brake goes up with the square of the mass increase.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the selected runway for your overweight landing is long enough and the weather is calm (so a smooth landing is easier), an overweight landing is not such a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's look at the 777-300ER in detail. I use the figures from &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, because the &lt;a href=&quot;http://www.boeing.com/commercial/777/&quot; rel=&quot;noreferrer&quot;&gt;manufacturer's site&lt;/a&gt; is trying much harder to hide the relevant data. The MTOW (maximum take-off weight, which is actually a mass) is 351,534 kg, and the maximum landing weight is 251,290 kg, about 100 tons less. Now let's assume that &lt;a href=&quot;https://aviation.stackexchange.com/questions/14099/how-much-fuel-does-it-take-to-start-land-an-aircraft-compared-to-normal-flight&quot;&gt;taking off&lt;/a&gt; and returning to the airfield uses 5 tons of fuel, so the mass ratio is 1.379. Therefore, the approach speed has to be 17.4% higher and the total kinetic energy at touchdown is higher by a factor of 1.9 compared to the case at maximum allowable landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we now assume that speed is reduced linearly during the landing run and that the wheel brakes will just absorb as much energy over time as in the case at maximum landing weight, the deceleration needs to be lower by the mass ratio, so the aircraft decelerates with only 72.5% of the deceleration at maximum landing weight. To shed its kinetic energy, the landing run will take longer by the increase in kinetic energy, i.e. 1.9. Since the average speed is also higher by 17.4%, the landing distance will be higher by a factor of 2.233 or 223% of the landing distance at maximum landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This neglects that the heating of the brakes is an instationary process, so you cannot simply brake with the same intensity for more than twice the time they were designed for. But this little estimation should illuminate what impact a higher landing mass has on the energy and distance involved.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-03T20:22:31.327" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="21534" PostTypeId="2" ParentId="21532" CreationDate="2015-10-02T11:37:49.920" Score="9" Body="&lt;p&gt;The major issue with landing a plane that is overweight is over-running the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are trying to land a plane that is over it's rated landing weight, you will need to be going faster to keep enough airflow over the wings to generate the lift required to keep the plane in the air. This, of course, has the consequence that it will take longer to stop when on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another factor that contributes to it taking longer to stop when on the runway is that the extra weight of the plane adds to the momentum. The calculation for momentum is p=mv where m is mass and v is velocity (for this example we can think of it as speed.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So not only are we now landing with a higher mass (m) we are also landing with a higher speed (v) so our momentum increases very quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if we had a plane that was 660,000 pounds, and needed to travel at (lets say) 290km/h (156 knots) to keep giving enough lift, it's momentum would be:&#xA;191400000 pounds km/h&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at a normal landing weight and speed of a 777 524,000 pounds landing at a normal speed of 250km/h then the momentum would be: &#xA;135500000 pounds km/h&lt;/p&gt;&#xA;&#xA;&lt;p&gt;you can see that even a small increase in speed causes the momentum to increase significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other issue is the load put on the landing gear which have the potential damage them, although I think that the deceleration speed is the bigger factor here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I am not a mathematician, my calculations may be wrong so feel free to edit the answer if I did get them wrong)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: One other thing I forgot to mention was that most larger airports have a special kind of surface at the end of the runway that serve to slow planes. They are constructed (iirc) out of some sort of very strong foam like material that is very effective at slowing a plane. I don't remember exactly what it was made out of though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned by NoviceInDisguise and ChrisW, this is actually called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Engineered_materials_arrestor_system&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Engineered materials arrestor system&quot;&gt;Engineered materials arrestor system&lt;/a&gt; and is made out of lightweight, crushable concrete blocks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see an image of the effect here where the plane's wheels have dug through the soft layer which helps slow the plane.:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n0Bhe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n0Bhe.jpg&quot; alt=&quot;Aircraft overrun&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11363" LastEditorUserId="11363" LastEditDate="2015-10-03T19:08:14.930" LastActivityDate="2015-10-03T19:08:14.930" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21535" PostTypeId="1" AcceptedAnswerId="21588" CreationDate="2015-10-02T12:23:56.147" Score="5" ViewCount="197" Body="&lt;p&gt;&lt;em&gt;another edit&lt;/em&gt;&#xA;To clarify - I'm programming an application for logbook tracking and want to automate turbine time calculations to help people fill in insurance firms easily. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;edit&lt;/strong&gt;: I guess a more general way to ask this is do &lt;em&gt;you&lt;/em&gt; consider turbo shaft to count towards turbine time? Do insurance companies have a standard opinion?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;original question&lt;/strong&gt;:&#xA;For insurance forms, when you are asked your turbine time, do you include all of the following in that hour calculation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Turboprop &lt;/li&gt;&#xA;&lt;li&gt;Turbojet &lt;/li&gt;&#xA;&lt;li&gt;Turboshaft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I want to make sure I'm not short changing my time, but don't want to put some helicopter specific turbine in my time if that isn't correct. As far as I'm concerned they &lt;em&gt;should&lt;/em&gt; count, right? It is, after all, only asking about the source of thrust not category of aircraft...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2015-10-03T00:57:04.873" LastActivityDate="2015-10-04T15:35:05.650" Title="Time Tracking: Does Turboshaft count towards Turbine time?" Tags="&lt;turbine&gt;&lt;insurance&gt;&lt;time&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21536" PostTypeId="2" ParentId="21518" CreationDate="2015-10-02T12:30:29.470" Score="19" Body="&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The pressure differential between the boiler and the cabin would be very large. I fear that this would result in the espresso machine being compromised.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pressure in the espresso machine is 9 bars, 14 in a good one. The difference in outside pressure is 0.3 bars. That is comparably tiny value that does not make any practical difference.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Water would boil at a much lower temperature (198°F / 92°C) resulting in the machinery not working correctly.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Coffee should not be made with boiling water anyway. 198°F / 92°C is sufficient for making coffee.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides, if the boiler was pressurized, the water would not boil until way higher temperature (it isn't, but it does not heat the water above boiling point at that pressure).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A sudden depressurization of the vessel could certainly result in a dangerous pressure differential resulting in explosive decompression.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pressurized content is water, not vapour, so it would not significantly expand if the machine cracked. After all, its pressure is relieved as part of normal operation (when the coffee drips to the pot) and it does not expand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And its amount is tiny compared to the total volume of the aircraft anyway. Very tiny, because the pressure is only in the pipe from the pump to the ground coffee.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;But that all assumes the coffee machine is espresso, which most of them are &lt;em&gt;not&lt;/em&gt;. Usually they will be just filter machines where the water flows by gravity at ambient pressure or perhaps at some pressure, but much lower than in a real espresso machine. I believe some airlines do advertise they serve true espresso though.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-10-02T23:01:20.893" LastActivityDate="2015-10-02T23:01:20.893" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21537" PostTypeId="2" ParentId="21532" CreationDate="2015-10-02T12:51:52.727" Score="5" Body="&lt;p&gt;An overweight landing is defined as a landing made at a gross weight in excess of the maximum design (i.e., structural) landing weight for a particular model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, landing overweight (though not desirable) is safe. &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_07/article_03_2.html&quot; rel=&quot;noreferrer&quot;&gt;FAA has stated&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There has been no adverse service experience with airplanes certificated under Part 25 involved in overweight landings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The major concerns for overweight landing are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Loads on the Landing Gear&lt;/strong&gt; The touchdown rates are higher in case of overweight landings. Touchdown at higher-than-normal sink rates may result in structural limits being exceeded. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, unless the pilot does a very hard landing, this should not be a problem. This is because regulatory requirements for landing gear design are based on a sink rate of 6 feet per second at the &lt;em&gt;maximum design takeoff weight&lt;/em&gt;, while the usual sink rate is nearly half of that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the wheel, brake and tire design is based on the most severe landing stop conditions at maximum wear out or a rejected landing at maximum take off weight, whichever is worse.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Landing Field Length&lt;/strong&gt; This becomes an issue only when the selected runway is smaller than the requirements. As the landing weight increases, the approach and touchdown speeds increases and the aircraft require more distance to decelerate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The landing length required is more as the weight increases and the aircraft field lengths are calculated for landing at MTOW. For example, for 777, according to Boeing, excess field length is available even for landing at MTOW.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fucoE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fucoE.png&quot; alt=&quot;Landing at maximum TOW&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Overweight Landing? Fuel Jettison? What to Consider&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Performance&lt;/strong&gt; Higher weight involves performance penalties as the control forces required are more.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Control&lt;/strong&gt; In most aircraft, for example in Boeings, the autopilot is not certified for overweight landings. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case an overweight landing has been carried out, there are some inspections required to be carried out:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Phase I&lt;/strong&gt; The aircraft is inspected for obvious signs of structural distress, such as wrinkled skin, popped fasteners, or bent components in areas which are readily accessible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Phase II&lt;/strong&gt; This is a much more detailed inspection required in case the Phase I inspection shows signs of excessive stress and requires opening access panels to examine critical structural components.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In general, overweight landings should pose no problems as long as the landing is performed correctly. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-02T12:51:52.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21539" PostTypeId="1" CreationDate="2015-10-02T15:28:57.587" Score="2" ViewCount="192" Body="&lt;p&gt;Have all the B-52s that are no longer in service already been &quot;guillotined,&quot; i.e. chopped in two to make them no longer flyable?&lt;/p&gt;&#xA;" OwnerUserId="11541" LastActivityDate="2015-10-02T16:09:24.227" Title="B-52s that are not in service demolished?" Tags="&lt;military&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21540" PostTypeId="1" AcceptedAnswerId="21541" CreationDate="2015-10-02T15:37:09.573" Score="6" ViewCount="14266" Body="&lt;p&gt;I'm playing Prepar3D and when coming in for a landing I'm usually told something like &lt;code&gt;Make left traffic, runway 19L&lt;/code&gt;. I'm not sure how to interpret this because I'm not a pilot.&lt;br&gt;&#xA;Should I go to the left of 19L for my downwind leg so the runway is to my right, or should I go to the right, with the runway on my left?&lt;br&gt;&#xA;Also with parallel runways should I go to the left of 19L exactly or is it the left of 1R? I'm very confused!&lt;/p&gt;&#xA;" OwnerUserId="11540" LastEditorUserId="64" LastEditDate="2015-10-02T16:46:29.610" LastActivityDate="2015-10-02T16:46:29.610" Title="What does the ATC instruction &quot;Make left traffic, runway 19L&quot; mean?" Tags="&lt;air-traffic-control&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21541" PostTypeId="2" ParentId="21540" CreationDate="2015-10-02T15:44:05.997" Score="8" Body="&lt;p&gt;'Left' or 'right' traffic means that when you are flying the traffic pattern, all turns are to that direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Airfield_traffic_pattern&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia article on traffic patterns&lt;/a&gt; isn't bad, and has some decent graphics, including this one from the FAA's Handbook of Aeronautical Knowledge:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tkX1i.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tkX1i.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The top pattern is left traffic, while the bottom pattern is right traffic.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-10-02T15:44:05.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21542" PostTypeId="2" ParentId="21539" CreationDate="2015-10-02T15:49:11.413" Score="1" Body="&lt;p&gt;Not necessarily, according to this picture of the &lt;a href=&quot;http://www.cnn.com/2012/06/08/travel/aviation-enthusiast-destinations/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boneyard&lt;/a&gt; there are still some intact full airframes (I believe those are B-52's)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eikUA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eikUA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.cnn.com/2012/06/08/travel/aviation-enthusiast-destinations/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth chopping an airframe in half only makes it no longer flyable in its current state. While it may sound crazy that is actually not an impossible thing to repair as long is its done properly. You can see some of the planes chopped up in the photo but I would assume that was done to either transport them to the boneyard (they were un-flyable) or they are going to be shipped out to fix another plane. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-02T15:51:51.747" LastActivityDate="2015-10-02T15:51:51.747" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21543" PostTypeId="2" ParentId="21539" CreationDate="2015-10-02T15:52:27.380" Score="3" Body="&lt;p&gt;No, some B-52H's in long term storage at the &lt;a href=&quot;https://en.wikipedia.org/wiki/309th_Aerospace_Maintenance_and_Regeneration_Group&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerospace Maintenance and Regeneration Group&lt;/a&gt; are in Type 1000 storage, which means,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft stored in near-flyaway condition. Can be stored without re-preservation for a period of 4 years. Aircraft stored under this category may be downgraded to Type 2000.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b7QIG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b7QIG.png&quot; alt=&quot;B-52s in AMRG&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: This screengrab is from Google Maps and I'm not sure when it was taken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USAF is under the process of &lt;a href=&quot;https://medium.com/war-is-boring/i-ll-be-damned-these-boneyard-b-52s-can-still-fly-4eec4c8bf5cf&quot; rel=&quot;nofollow noreferrer&quot;&gt;reclaiming a B-52H&lt;/a&gt; from the Boneyard as a replacement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AA0fm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AA0fm.jpg&quot; alt=&quot;B 52H Ghost Rider&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: foxtrotalpha.jalopnik.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;a href=&quot;http://www.militarytimes.com/article/20131228/NEWS04/312280002/Last-B-52G-eliminated-under-nuclear-arms-treaty&quot; rel=&quot;nofollow noreferrer&quot;&gt;all the B-52G models have been destroyed&lt;/a&gt; in compliance with the &lt;a href=&quot;https://en.wikipedia.org/wiki/New_START&quot; rel=&quot;nofollow noreferrer&quot;&gt;New START&lt;/a&gt; treaty.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-02T16:09:24.227" LastActivityDate="2015-10-02T16:09:24.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21544" PostTypeId="1" AcceptedAnswerId="21557" CreationDate="2015-10-02T16:15:10.333" Score="4" ViewCount="1209" Body="&lt;p&gt;I am a new aircraft designer, and work for a small company (which doesn't have the enormous resources of a Boeing or Lockheed) so we have to work with limited resources to get good at our trade. I've been looking over different approaches for becoming a master designer, and for learning the shortcuts and tips all great designers pickup over the years of practicing their art. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From reading, it seems most good designers got their experience by essentially apprenticing with great engineers, or having the freedom to try stuff and see if it worked or not. I was thinking how a designer could get good in a small company like mine and came up with the following options:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Leave the company for a larger, better funded company like Boeing and come back&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros: Have freedom to try stuff since company has the budget to absorb mistakes, and get to interact and learn from experienced engineers at company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cons: From all the people I talk to, nobody can take an aircraft (even a model) to full completion since the big companies compartmentalize the skills they pick up, meaning they good at making their widget or subsystem, but never work on integrating everything together to make the whole system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Build a lot of R/C models to learn the fundamentals by flying, crashing, and repairing the aircraft &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros: Get a ton of flight experience and building experience so will quickly learn what works, what doesn't work, and learn how to take aircraft from design to flight fully. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cons: Aerodynamics do not fully scale unless the R/C models are somewhat large (around the 10-15 kg mass), which means crashes, even minor ones, cause a LOT of damage, which gets costly quickly. Replacing busted motors, shafts, wings, and the time that is needed to do this can quickly eat into any real experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) Use a digital flight simulator like X-Plane or Kerbal Space Program to learn what flies and doesn't &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros: This is the ultimate for cheapness. I can design and crash an infinite amount of times at no additional cost, as well as fly the aircraft at full scale and see all of the response characteristics in a variety of conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cons: Building the aircraft in the physical world does not mirror how its built in the software, meaning a lot of new factors (like weight gain, manufacturing inaccuracies) come into change how the actual aircraft flies compared to the simulator aircraft. Also, the simulator has limitations in its physics model, so things like stall behavior or transsonic drag will differ significantly between simulator and real life. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) Use a hybrid system, using 3D printing, modular parts, R/C aircraft, and flight simulators&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros: This will teach me how to take a design to completion by first designing/flying aircraft in simulator using modular parts (like in Kerbal Space Program), then print those modular parts (wing sections, fuselage sections, wing/fuselage joints, etc.) in real life using 3D printers, and assemble the aircraft at small R/C scale to fly, before finally going to full scale using the same modular parts, only scaled up. It lets me make mistakes and learn without bankrupting the project since I learn how to avoid the big mistakes while the consequences are still small. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cons: I will need to design and build modular blocks light enough with the same performance as that in the simulator at both R/C and full scale. Also, while somewhat easy for airframe components, building engines this way would still be costly, as some combustion engines have different performance at small scales than large scales (heat leakage and manufacturing tolerances become more important at the small scale than at large scale) meaning it might cost too much to build the system of modular parts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What option did designers like Burt Rutan use for getting good at aircraft design?&lt;/p&gt;&#xA;" OwnerUserId="11161" LastEditorUserId="11161" LastEditDate="2015-10-02T17:01:29.670" LastActivityDate="2015-10-02T21:07:00.670" Title="What do aircraft designers like Burt Rutan do to cheaply practice geting good at designing aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-development&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ClosedDate="2015-10-02T21:03:29.190" ContentLicense="CC BY-SA 3.0" />
  <row Id="21545" PostTypeId="1" AcceptedAnswerId="21566" CreationDate="2015-10-02T16:34:30.307" Score="4" ViewCount="1178" Body="&lt;p&gt;I have heard a lot about keeping the centre of gravity (CG) behind the aerodynamic centre (AC)will give better performance than keeping CG ahead of AC (for UAVs require high performance). However, I could not find any example UAV/glider/sailplane which operates with CG behind AC. Can some one tell me whether there are any existing UAV/glider/sailplane with CG behind AC position? &lt;/p&gt;&#xA;" OwnerUserId="11544" LastEditorUserId="19" LastEditDate="2016-07-08T09:24:46.463" LastActivityDate="2019-09-06T00:42:10.270" Title="What is the effect of moving the centre of gravity ahead or behind the aerodynamic centre for HALE UAVs?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;cg&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21546" PostTypeId="1" AcceptedAnswerId="21548" CreationDate="2015-10-02T17:09:39.200" Score="4" ViewCount="5682" Body="&lt;p&gt;When flying IFR under the FAA the departure procedure starts with copying an IFR clearance from ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, how long before departure is it okay to go ahead and copy down the clearance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes clearances include void times. The context of my question is for clearances delivered, for example, be clearance delivery at a towered airport. These clearances don't include void times. What't the time limit on these clearances?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-02T18:03:41.667" Title="How long before departure can an IFR clearance be copied?" Tags="&lt;radio-communications&gt;&lt;instrument-flight-rules&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21547" PostTypeId="2" ParentId="21546" CreationDate="2015-10-02T17:31:39.260" Score="4" Body="&lt;p&gt;You can generally get your clearance 30 minutes prior to the departure time you listed on your flight plan.  If you call clearance delivery prior to that they likely won't have it and will tell you to call back 30 minutes prior to departure.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-10-02T17:31:39.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21548" PostTypeId="2" ParentId="21546" CreationDate="2015-10-02T18:03:41.667" Score="3" Body="&lt;p&gt;You kind of have two questions in one - &lt;strong&gt;When can I call Clearance Delivery to get my clearance?&lt;/strong&gt; and &lt;strong&gt;How long is that clearance good for?&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/21547/64&quot;&gt;Casey covered the first part&lt;/a&gt; - the local controllers will usually have your clearance 30 minutes before your scheduled departure.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sometimes&lt;/em&gt; you can get this information a little earlier yourself - the new Flight Service tools like &lt;a href=&quot;http://1800wxbrief.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;1800WXBRIEF.com&lt;/a&gt; can give you expected clearance and flight plan routing information based on what you filed, if the ATC computer already knows what it's going to do with your flight. &lt;a href=&quot;http://blog.foreflight.com/2014/04/14/cleared-as-filed-with-amend/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here's a few words about it from the Foreflight folks&lt;/a&gt;, and you can do the same thing yourself with the Lockheed-Martin tools with a few more manual steps.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You still need to talk to the controllers but if you know what they're going to say it makes that conversation faster!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The second part can go one of two ways: The point of the &quot;void time&quot; is that the ATC system is reserving a spot in the system for you up until that specific time. After that ATC is going to let other aircraft use the airspace they were holding for you (they may allow someone to make an instrument approach to the airport you're leaving from, for example).&lt;br&gt;&#xA;This is used a lot for non-towered fields where you have no local controller to talk to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearances from Clearance Delivery at a towered field &lt;em&gt;can&lt;/em&gt; include a void time, but they generally don't because they assume you're in the plane and ready to go at or around the time you call in, and you have local controllers to talk to if you have a problem during the run-up or something which delays your departure. Basically the clearance is good until someone tells you otherwise in that situation.&lt;br&gt;&#xA;The tool that gets used at towered fields more often is &lt;code&gt;Hold for release&lt;/code&gt;: You've been issued a clearance, but you can't execute it until the tower has coordinated you a spot in the airspace. This is generally more efficient than reserving airspace with a clearance and void time when there are controllers to talk to, and if everything is working well your release should be ready right around the time you're ready to take the runway for departure.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-02T18:03:41.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21549" PostTypeId="2" ParentId="9063" CreationDate="2015-10-02T18:19:52.480" Score="-4" Body="&lt;p&gt;A takeoff clearance cannot be revoked. Once you issue a clearance the aircraft is CLEARED for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the tower realizes that something that will obstruct or threaten an aircraft taking off is present, all they can do is inform the PIC of the situation. At that point it is up to the PIC to figure out what to do. They might try to abort the takeoff or perform an evasive maneuver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To clarify you this for you: a tower cannot tell an aircraft to abort a takeoff because they are not qualified to make that determination. The guy in the tower neither is qualified nor can see the instruments of the aircraft so they have absolutely no idea whether it is safe to abort a takeoff or not. Therefore, they will never tell a pilot to abort a takeoff once it is underway. All they can do is cancel the clearance (See Section 9. Departure Procedures and Separation in FAA ATC guidelines). The phraseology is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Call sign] Cancel Takeoff Clearance [state reason]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course, if the aircraft has reached V1 it will not abort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In situations I have been in where something bad has happened is that the tower will just tell the pilot what to do. Like if some plane tries to land the wrong way on a runway when you are taking off, the tower will say &quot;[call sign] Bear right immediately, traffic dead ahead!&quot; So, you basically try to veer to the right to avoid the head on collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your specific questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Exactly what happens in the control room?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a crisis scenario, the tower guy will say whatever he/she thinks is necessary to avoid a collision. Once I had a near collision because another guy was not where he supposed to be, but I was the one with comm, so she moved me by screaming &quot;TURN LEFT RIGHT NOW !!!&quot; Phraseology goes out the window when you are 0.5 seconds away from a huge fireball with multiple fatalities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What does the ATC do and how does he/she make sure pilots understand the cancellation?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I gave the phraseology above.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How do the pilots in the aircraft taking off respond? Are they trained for this scenario?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can safely abort, you abort and slam on the brakes. If not, you keep going and try to maneuver around whatever it is, moose, truck, whatever. Pilots are trained to never abort when they reach V1. Other than that it is experience and nerves that count, no more training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is a takeoff cancelled even after V1?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cancelling is what the tower does. Aborting is what the pilot does. The tower cannot &quot;cancel after V1&quot; because they have no way of knowing if the plane is at V1 or not. A pilot will almost never abort after V1 because the consequences of going 100 miles an hour off the runway are almost always worse than the consequences of going 100 mph in the air. If an unavoidable obstruction occurs, like a plane rolls onto the runway in front of you, and you are at V1 you still takeoff, you just try to do it sooner. &lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-02T18:41:18.677" LastActivityDate="2015-10-02T18:41:18.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21552" PostTypeId="2" ParentId="21518" CreationDate="2015-10-02T18:52:09.003" Score="3" Body="&lt;p&gt;As the boiling point of water at 0.7bar absolute is 90C, there would be one small difference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The specific enthalpy of water at these conditions is 376.783kJ/kg and the specific enthalpy of vaporization is 2282.81kJ/kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the machine heats the water to 95C, it will reach a specific enthalpy of 398.017kJ/kg, an excess of 398.017-376.783 = 21.234kJ/kg. There will therefore be flash boiling of 21.234/2282.81 x 100 = 0.93% of the coffee by mass. Although that doesn't sound much, water expands 2461 times when boiled under these conditions. So the volume of steam produced will be 2461 x 0.0093 = 22.89 times the volume of the coffee.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, the water in an espresso machine is boiled under pressure at 9 bar and then forced through the coffee and released at ambient pressure. If this is done without adjusting the thermostat on the boiler, significant boiling will occur due to the pressure drop, possibly causing over-agitation of the coffee and / or vapour lock (inability of water to enter due to the volume of steam.) I can't drink coffee for medical reasons so I'm no expert on coffee, but neither of these sounds like a good thing. The thermostat on the water boiler should be adjusted below the boiling point of water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand good quality espresso machines have an independent boiler for generating steam. That should be fine and can be left untouched.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have said, the difference between 1 bar and 0.7 bar ambient is of no consequence for the boiler if it normally operates at 9 bar. There is some possibility of erosion of water valves if superheated water flashes to steam within them due to the drop in pressure.&lt;/p&gt;&#xA;" OwnerUserId="1952" LastActivityDate="2015-10-02T18:52:09.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21553" PostTypeId="2" ParentId="17485" CreationDate="2015-10-02T19:22:13.727" Score="2" Body="&lt;p&gt;acturally, the colour change is not acurally RAM coating, but sensors to indicate what a a incoming object (such as a misslile) are coming at a plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To avoid radar the f22 actually used &lt;a href=&quot;https://en.wikipedia.org/wiki/Stealth_technology#Vehicle_shape&quot; rel=&quot;nofollow&quot;&gt;PLANFORM ALIGNMENT&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user8732" LastActivityDate="2015-10-02T19:22:13.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21554" PostTypeId="1" AcceptedAnswerId="21558" CreationDate="2015-10-02T20:17:28.460" Score="5" ViewCount="1014" Body="&lt;p&gt;I recently flew from a small airport under a Bravo shelf into the nearby Bravo airspace above. When I advised the ground controller that I was doing as such, he cleared me to taxi, then added the frequencies for the Bravo approach control and said &quot;code on request&quot;. A moment later he came back with a discrete squawk code. I'm assuming &quot;code on request&quot; meant he had requested a squawk code from approach control and was waiting for the reply, am I correct? Is any response required by me? I got my PPL at a smaller airport and had never heard that before.&lt;/p&gt;&#xA;" OwnerUserId="1736" LastActivityDate="2015-10-02T21:26:39.027" Title="What is meant by the term &quot;Code on request&quot;?" Tags="&lt;air-traffic-control&gt;&lt;general-aviation&gt;&lt;clearance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21556" PostTypeId="1" CreationDate="2015-10-02T20:35:35.310" Score="2" ViewCount="341" Body="&lt;p&gt;&lt;strong&gt;Regarding the 1902 Wright glider. Why is the airspeed, Va, calculated adding the ground speed, Vg, and wind speed, Vw?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In August 1903, Octave Chanute published in L'Aerophile a table (see attached) showing the measured quantities: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) distance traveled along the ground (col. 2), &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) flight time (col. 3), &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) wind speed (col. 5),&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(4) glide angle (col. 7),&lt;/p&gt;&#xA;&#xA;&lt;p&gt;corresponding to a few flights performed on Oct. 8, 1902. From these parameters and the total mass of the machine and pilot, O. Chanute calculated that the 1902 glider lifted about 62 kg/hp (see the last column).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not quite clear for me why Va = Vg + Vw (see col. 6). The airspeed should be constant, independent of the headwind speed, as long as the glide angle is the same because the thrust is the same. It is true Va = Vg + Vw but if Vg added to Vw does not give always a constant Va, for the same glide angle, then something is wrong with the measurements.&#xA;The water speed of a boat traveling upstream depends only on its thrust and is independent of the river speed.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift in the table (~62 kg/hp) is quite big in comparison to the lift of the best gliders of the time, mentioned by O. Chanute a few lines below the table, that lifted only 45 kg/hp.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The precise value of the airspeed, Va, is essential in calculating the lift. If ones takes it only 1-2 m/s lower, due to miscalculations, then the evaluated lift grows artificially.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wFmPp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wFmPp.jpg&quot; alt=&quot;1903/08, O. Chanute, &amp;quot;Table parameters glided flights, Kitty Hawk, 8 Oct. 1902&amp;quot;, L&amp;#39;Aerophile, pag. 180&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://gallica.bnf.fr/ark:/12148/bpt6k65534693/f190.item.r=wright&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://gallica.bnf.fr/ark:/12148/bpt6k65534693/f190.item.r=wright&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Update&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few sources of errors that could have altered substantially the results in the table. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) O. Chanute wrote, above the table (see the link), the Wrights did not drift, more than 1/4 in a arc of a circle from the straight line, to always have good headwinds. This drift increases the traveled distance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) The glider was first lifted as a kite to a few meters above the ground with the help of two men. This height made the glide angle to be higher than that of the slope, which can be estimated from a picture (see the attached image where the glide angle appears to be 9.01 deg). &#xA;If instead of 7 deg 20' the slope angle was 9.01 deg and the 1902 machine started from a few meters above the ground then instead of 58.1 kg / hp it would have lifted less than 114.4 kg / (114.4 kgf * sin(9 deg 20 minutes) * (54.7 m/12 s + 5.68 m/s) ) = 47.4 kg/hp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) The third factor of incertitude is the wind speed that varies with altitude being stronger a few meters in the air than close to the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yJQLi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yJQLi.jpg&quot; alt=&quot;Wright glider 1902&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;Wright glider, 1902. Undated picture.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;: Do you know a modern replica of the 1902 glider that lifts ~62 kg/hp?&#xA;If such a thing exists then the 1902 machine could have lifted 62 kg/hp.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-03T11:57:05.987" LastActivityDate="2015-10-03T11:57:05.987" Title="Regarding the 1902 Wright glider. Why is the airspeed, Va, calculated adding the ground speed, Vg, and wind speed, Vw?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21557" PostTypeId="2" ParentId="21544" CreationDate="2015-10-02T21:07:00.670" Score="9" Body="&lt;p&gt;Let's look at every of your concepts:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Joining a large company: As you noticed yourself, you won't get a broad range of skills, but a deep understanding of a narrow field, unless you rotate between departments every few years. This will be hard to pull off, and will take time. If you are good at what you do, your boss will try to keep you (they always try to promote the duds away in big companies, and the good people get stuck. Really!)&lt;/li&gt;&#xA;&lt;li&gt;Building RC models is great if you want to become a configuration expert at low speed aerodynamics. You will gain no experience in transsonic aerodynamics, structure, systems - 90% of the needed knowledge cannot be gained from model aircraft. But after 20 models you will be great at understanding flight mechanics and the pros and cons of different configurations.&lt;/li&gt;&#xA;&lt;li&gt;Forget flight simulators. Things only get interesting once you leave the realm of attached flow. Stalls, spins, flutter, oscillating shocks - that is what you need to understand when you want to do good work, and flight simulators will not teach you this. At all. Also important is to understand the effect of single failures on the whole aircraft, and designing for robust response. Again, no simulator will give you anything even resembling a realistic response.&lt;/li&gt;&#xA;&lt;li&gt;Hybrid: Now we are talking: Keep your eyes and ears open! Visit conferences, museums, exhibitions and talk to the people. Get a pilot's license and fly yourself! Read books and technical reports. Be open to all things, be it metallurgy, fuel chemistry or whatever. Try to do stints in workshops and flying clubs. Volunteer for workshop duty and do maintenance and repairs. Don't be shy to ask, and if you see something strange, don't stop until you have arrived at a convincing explanation. Do this 10 hours a day for 10 years, and you will collect the necessary all-around knowledge.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The best way will be to participate in as many aircraft design projects as possible, from start to finish. This has become extremely hard, and some engineers will spend their whole professional life working on just one design. Let's face it, the golden days where you would work on a new design every year were maybe 80 years ago. On the other hand, the Internet can bring you an incredible wealth of information and past experiences from which to learn. Like this site. Use it!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-02T21:07:00.670" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21558" PostTypeId="2" ParentId="21554" CreationDate="2015-10-02T21:09:46.293" Score="4" Body="&lt;p&gt;Yes, I think you're correct although the phrasing is unusual. The usual phrase is &quot;clearance on request&quot;, which is used for IFR departures as explained nicely in &lt;a href=&quot;http://flighttraining.aopa.org/magazine/1998/September/199809_Flying_Safe_Checkride.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this AOPA article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Experienced instrument pilots know that when they call to request&#xA;  their clearance, the controller may not yet have received it.&#xA;  &quot;Clearance on request&quot; is ATC's way of politely saying &quot;I don't have&#xA;  it - I've requested it - you'll be the first to know when I get it!&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The only FAA reference for the phrase that I could find is buried in the glossary of the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Appendix-Glossary-Index.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Clearance on request.&lt;/strong&gt;  An IFR clearance not yet received  after filing a flight plan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But as RalphJ &lt;a href=&quot;https://aviation.stackexchange.com/questions/21554/what-is-meant-by-the-term-code-on-request/21558?noredirect=1#comment48981_21558&quot;&gt;commented&lt;/a&gt;, if this is a VFR scenario and you needed a class B clearance and transponder code then I assume that the controller said &quot;code on request&quot; to let you know that he was waiting for a transponder code for you, as you assumed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It wasn't an instruction as such so you could just acknowledge it with &quot;Roger&quot; or whatever. See &lt;a href=&quot;https://aviation.stackexchange.com/q/279/62&quot;&gt;this question&lt;/a&gt; for more information on that.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-02T21:26:39.027" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21559" PostTypeId="2" ParentId="21556" CreationDate="2015-10-02T21:09:59.237" Score="4" Body="&lt;p&gt;The gliders had no instruments of any kind, let alone an airspeed indicator. Thus the only way to measure airspeed was to measure the windspeed and add that to the speed over the ground, itself calculated from distance flown and time aloft for each flight.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-02T21:09:59.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21560" PostTypeId="1" CreationDate="2015-10-03T02:29:20.957" Score="4" ViewCount="1680" Body="&lt;p&gt;Many aircraft accidents have been caused by downbursts. A downburst is basically a strong downward wind that forces the aircraft toward the ground and causes it to crash. Is it possible for an airliner to escape the downburst and land safely with this much force pushing down on an aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a downburst illustration: &lt;a href=&quot;https://i.stack.imgur.com/k5BpU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k5BpU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:(www.mikesmithenterprisesblog.com) &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="6886" LastEditDate="2015-10-05T06:34:24.937" LastActivityDate="2015-10-05T06:34:24.937" Title="Can an airliner fly out of a downburst?" Tags="&lt;airliner&gt;&lt;accidents&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21561" PostTypeId="2" ParentId="21560" CreationDate="2015-10-03T02:42:29.417" Score="6" Body="&lt;p&gt;&lt;em&gt;'this much force'&lt;/em&gt; - how much force? Down bursts vary in size, location and intensity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airliner encountering an intense downburst just off the end of the runway will almost certainly crash as there will be insufficient time for the crew to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same aircraft encountering a less intense event some distance from the threshold at, say, 2000' may give the passengers an exciting ride but may be able to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It all depends...&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-03T02:42:29.417" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21562" PostTypeId="2" ParentId="21560" CreationDate="2015-10-03T03:32:06.393" Score="16" Body="&lt;p&gt;First take a look &lt;a href=&quot;http://www.erh.noaa.gov/cae/svrwx/downburst.htm&quot;&gt;http://www.erh.noaa.gov/cae/svrwx/downburst.htm&lt;/a&gt; for info on downbursts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft encountering a microburst (the more localized form of a downburst and that which airline crews train for) can counter it in two basic ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;establish, if possible, a climb rate through the descending air that is greater than the downward vertical speed of the air.&lt;/li&gt;&#xA;&lt;li&gt;fly through the column of descending air to air that is not descending or is at least descending at a lesser rate&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;And, of course, do this without stalling the airplane, especially as you come out of the burst. A practical scenario is that your max climb rate through the descending air can at least reduce your descent rate toward the ground enough that you will be able to transit the burst before hitting the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was never in a full blown microburst for real, but I practiced recovering from them many times in simulators. For 747-100/200 aircraft in the 1990s the procedure was:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;thrust levers all the way forward&lt;/li&gt;&#xA;&lt;li&gt;raise the nose until you get the stick shaker&lt;/li&gt;&#xA;&lt;li&gt;fly the aircraft straight ahead while keeping the speed solidly in the stick shaker range.&lt;/li&gt;&#xA;&lt;li&gt;do not change the aircraft configuration, in other words don't mess with the flaps or the gear.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In simulators it's a wild ride. You can tell how far into the stick shaker range you are by the frequency of the shaker by feel and by its noise. The closer you get to an actual stall, the faster the stick shaker will go, so the idea was to keep the shaker on but not too fast. Since the airspeed will be varying rapidly, you have to do that with large pitch changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was controversy back in the 1990s as to whether what we were trained to do was actually the best way, especially as to not changing the aircraft configuration and how deep to go into the stick shaker. Perhaps now the thinking is different.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-10-03T03:32:06.393" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21563" PostTypeId="2" ParentId="21518" CreationDate="2015-10-03T11:11:14.477" Score="3" Body="&lt;p&gt;Unfortunately, the accepted answer is off the mark. :-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Espresso is extracted at 9 bars, even in so called &quot;good&quot; or &quot;decent&quot; espresso machines. The source of this misunderstanding is that most manufacturers state the rated pressure the pump inside the machine is capable of delivering (and consumers are often led to believe that bigger is better). The pressure is regulated to 9 bars when the espresso is actually brewed (with slight differences possible depending on the individual service setting of the machine in question). There is a pressure relief valve that simply sends the excess back to the water tank. Espresso coffee extraction is an equilibrium of many factors, including quantity, temperature and time. It's actually not even desirable to have a higher pressure than the traditional, tried and tested 9 bars, together with all the other standard parameters used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's more important in the context of the question is that &lt;strong&gt;an espresso machine is not a pressurized container of hot water.&lt;/strong&gt; The 9 bars are created by a pump that only operates while the machine is actually pushing the water through the ground coffee. The amount of water is rather small (a serving of espresso is 30 ml, it's usual to have two-cup sprouts, meaning 60 ml). In any event of breach of pressure (eg. the portafilter accidentally knocked off), the pressure will fall immediately because it is only built up against the ground and packed coffee, nothing else inside the machine. With no resistance, the pump simply continues to deliver hot water, like a tap. So, the result could be a small amount of scalding hot water for anybody standing close, which &lt;em&gt;is&lt;/em&gt; a nasty thing but certainly no risk to general aircraft safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, it could be added that using a boiler to keep any amount of hot water is more characteristic of the traditional espresso machines used in catering and by connoisseurs at home. The kind of machine more likely to be used on board of an aircraft, the so-called superautomatic type (this is the combined machine that grinds the beans and brews the espresso at the touch of a button) tend to use heaters that simply heat the water flowing through them during the brewing process. This reduces the startup time of the machine and requires less electricity, although it produces espresso of lesser quality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of this setup, the pump would deliver the same pressure at any flying altitude. It's the pressure relief valve that actually decides the pressure, not the pump. If it stays set at 9 bars, that's what will be used during the brewing process. What the altitude would influence is the temperature we can heat the water to before it starts to boil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Espresso brewing needs to avoid boiling water at the usual ground level primarily because of the temperature limit of 100°C. It's not the boiling itself that would ruin the espresso (apart from the fact that steam, being compressible, would not work in a pump set up to send high pressure water through the coffee puck) but the high temperature: the aromatic ingredients in the coffee bean can only be extracted, exactly as the OP has stated, in a rather narrow temperature range and going near or above 100°C simply ruins the taste. In this respect, if ambient pressure differences would decrease the usable temperature range at higher altitudes (say, 92°C being the highest temperature of water that can be achieved before boiling), this would only require a different selection of coffee on board, one that tastes good when extracted at that temperature (probably meaning that both the composition of the blend and the roasting process should be adjusted accordingly but this task would be simply left to the supplier).&lt;/p&gt;&#xA;" OwnerUserId="11549" LastEditorUserId="11549" LastEditDate="2015-10-03T13:29:21.370" LastActivityDate="2015-10-03T13:29:21.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21564" PostTypeId="1" AcceptedAnswerId="21565" CreationDate="2015-10-03T11:15:56.227" Score="15" ViewCount="4465" Body="&lt;p&gt;I saw this plane yesterday:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uzHkm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uzHkm.jpg&quot; alt=&quot;What is this plane?&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this plane? And what is the reason for it's odd-looking nose?&lt;/p&gt;&#xA;" OwnerUserId="8623" LastActivityDate="2015-10-03T11:47:03.560" Title="What is this oddly-shaped plane?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21565" PostTypeId="2" ParentId="21564" CreationDate="2015-10-03T11:18:02.113" Score="25" Body="&lt;p&gt;It is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_Beluga&quot; rel=&quot;noreferrer&quot;&gt;Airbus A300-600ST (Super Transporter) Beluga&lt;/a&gt;, which is a version of the A300 wide-body airliner modified to carry aircraft parts and oversized cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SHDrc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SHDrc.jpg&quot; alt=&quot;Airbus Beluga&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: berlin-aviation-forum.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose is shaped like that as the upper portion is basically a cargo hold and is used to transport oversize cargo, especially aircraft parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bzs3w.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bzs3w.jpg&quot; alt=&quot;Airbus Beluga&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-GSTB_-_2_Airbus_A.300B4-608ST_Beluga_Airbus_(8634655670).jpg#/media/File:F-GSTB_-_2_Airbus_A.300B4-608ST_Beluga_Airbus_(8634655670).jpg&quot; rel=&quot;noreferrer&quot;&gt;F-GSTB - 2 Airbus A.300B4-608ST Beluga Airbus (8634655670)&lt;/a&gt;&quot; by aeroprints.com. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpit was lowered below the cargo deck so that the cargo area could be loaded without having to disconnect any of the vital electric and hydraulic lines running to the rest of the plane. However the A300’s lower fuselage, wings and landing gears were retained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the changes that were made in the nose section from A300 to the Beluga.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rrheZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rrheZ.jpg&quot; alt=&quot;Nose change&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: allaboutguppys.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-03T11:47:03.560" LastActivityDate="2015-10-03T11:47:03.560" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21566" PostTypeId="2" ParentId="21545" CreationDate="2015-10-03T12:41:58.693" Score="3" Body="&lt;p&gt;Glider pilots in a competition will try to place the center of gravity at the most rearward position possible, sometimes even further back than permitted. This will make the glider statically unstable, but the performance will not be much improved - this is more psychological than real. Don't discount psychology in competitions: Pilots who feel that they fly an inferior plane will take bigger risks to get ahead and have a much higher chance of spoiling their chances by doing something stupid. Therefore, everyone tries to tweak their plane, even if the tweaking only helps to give a good feeling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the physics: If the center of gravity (CG) is right above or below the aerodynamic center (AC), the aircraft's longitudinal static stability is indifferent. Move it forward and stability increases, move it further back and the plane becomes unstable. The aerodynamic center is where the angle-of-atttack-dependent lift forces act, and in an indifferent configuration the lift coefficient on wing and tail will be equal. Since the aspect ratio of the wing is normally larger than that of the tail, an indifferent configuration will already produce slightly more induced drag for the same lift than a slightly stable configuration. Details depend on the lift loss at the center of the wing due to the fuselage and the combined vorticity of wing and tail, but as a first approximation the above is valid. Moving the CG further aft only makes matters worse. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it can be argued that the rear CG location helps in maneuvering the aircraft. This might even be helpful with gliders, since they need to maneuver quickly into the center of a thermal, but HALE (high altitude long endurance) UAVs fly mostly straight, so maneuvers will be few, slow and deliberate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In essence, moving the CG back in a very stable configuration helps, but the optimum is reached already before the CG reaches the AC. Moving it back even further is detrimental to performance and runs the risk of stalling the tail first due to its high loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know of any HALE which flies in a statically unstable configuration, and the glider pilots who do will not openly talk about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only application of static instability (CG behind AC) which boosts performance can be found in supersonic aircraft. And the performance improvement is most pronounced in supersonic flight because it reduces the losses from stability of a highly stable configuration. When incorporated from the start, subsonic instability &lt;a href=&quot;https://aviation.stackexchange.com/questions/34458/is-the-sepecat-jaguars-design-aerodynamically-inferior-to-more-modern-jets/34460#34460&quot;&gt;enables the aircraft to use smaller wing and tail surfaces&lt;/a&gt; because both will work less against each other at supersonic speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-09-06T00:42:10.270" LastActivityDate="2019-09-06T00:42:10.270" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="21567" PostTypeId="2" ParentId="21499" CreationDate="2015-10-03T13:02:01.457" Score="2" Body="&lt;p&gt;The phenomenon is called trimming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the process by which the pilot adjusts the lift at the tail surface to shift the center of pressure right above or below the center of gravity and removes any stick force so the airplane will keep this attitude unaided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the center of gravity (CG) is right above or below the aerodynamic center (AC), the aircraft's longitudinal static stability is indifferent. Move it forward and stability increases, move it further back and the plane becomes unstable. The aerodynamic center is where the angle-of-atttack-dependent lift forces act, and in an indifferent configuration the lift coefficient on wing and tail will be equal. Increasing stability thus means to reduce lift at the rear surface, and if a lot of stability is desired, lift at the rear surface will become negative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the airplane is hit by a gust (change in vertical wind speed), the angle of attack at both wing and tail will change by the same amount. Now it is important how much lift changes relative to the lift before the gust. If the lift coefficient on the wing is larger than on the tail, the same amount of angle of attack change will cause a relatively smaller change of lift on the wing than on the tail, and the center of pressure will move such that it causes a correcting pitch moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By selecting the proper center of gravity location, the pilot can adjust the level of stability he/she desires. To stay at the desired attitude in flight, he/she now has to move the incidence of the empennage (or the elevator deflection) to a point where any pitch moment disappears. The consequence is a downforce on the tail if that is what it needs to trim the aircraft with the given center of gravity location.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-12-23T15:40:11.957" LastActivityDate="2017-12-23T15:40:11.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21568" PostTypeId="1" CreationDate="2015-10-03T13:24:34.097" Score="13" ViewCount="14439" Body="&lt;p&gt;I've heard many articles about crosswind correction in VOR holding pattern. They mainly tell the outbound leg=correction times three things for slow speed aircraft. I notice all of them require wind information in holding pattern. What if somehow under some circumstances the pilot doesn't have the wind information whatsoever in holding pattern? Like the wind may change unexpectedly. Is there any method to maintain precise 4 minutes holding pattern in such condition?&lt;/p&gt;&#xA;" OwnerUserId="9078" LastEditorUserId="19" LastEditDate="2016-07-28T16:31:54.580" LastActivityDate="2018-03-25T03:46:48.837" Title="How to correct for crosswind in VOR holding pattern without wind information?" Tags="&lt;instrument-procedures&gt;&lt;crosswind&gt;&lt;holding&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21569" PostTypeId="2" ParentId="9466" CreationDate="2015-10-03T14:04:50.303" Score="1" Body="&lt;p&gt;Barnes Wallis asked this question in the 1940s. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The loss of life in the Dams Raid deeply affected him and he was adamant that he would not risk human life on his more experimental post-war designs until their basic concepts were proven through unmanned flight. (&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0711011192&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt; for this and details below)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These included the revolutionary Wild Goose and later Swallow designs, where variable geometry wings were used, not just to improve wing efficiency across a range of flight conditions (as in the much later F-111 and Tornado) but to eliminate the tail and its associated weight and drag penalties altogether. Wild Goose flew (remotely controlled) in January 1950. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However testing seems to have been slow and remote control techniques of the time didn't help. Without onboard cameras, at least one model was crashed by a pilot misjudging its position from a distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Swallow (in the form of a rocket propelled model) is reported to have flown stably at Mach 2.5 in 1955.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither progressed to manned prototypes, thanks in part to financial difficulties in post-war Britain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case the intent was to prove the basic concepts rather than perform all testing in unmanned form, experimental manned planes were to be built along proven aerodynamic lines.&lt;/p&gt;&#xA;" OwnerUserId="4068" LastActivityDate="2015-10-03T14:04:50.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21570" PostTypeId="2" ParentId="18847" CreationDate="2015-10-03T14:27:34.280" Score="6" Body="&lt;p&gt;Part of the reason is that large engines tend to be thermodynamically more efficient than small ones, and this isn't specific to any one type of engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretical engine cycle is understood in terms of compressing, heating, expanding volumes of gas in an ideal environment. The closer the engine approximates to that environment the closer the engine can get to its ideal efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Relatively cool metal surfaces like combustion chamber walls, or pistons and cylinder liners, detract from this, so the further you can keep the gas from the metal, (i.e. the larger the engine) the more efficient (for the same theoretical cycle).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Off-topic, large marine diesels can exceed 50% thermodynamic efficiency while small diesels may reach 40% &lt;a href=&quot;https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption#Examples_of_values_of_BSFC_for_shaft_engines&quot; rel=&quot;noreferrer&quot;&gt;as seen here&lt;/a&gt;. The same table shows this applies to gas turbines too, comparing a 36 MW gas turbine (Trent, 39.8%) to a 2.20MW one (P&amp;amp;W PW127, 27%) but these are just example numbers, not a really fair comparison. (It would be nice to see like-for-like-but-bigger comparisons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So larger engines tend to have higher thermodynamic efficiency, it just so happens you also need fewer of them.&lt;/p&gt;&#xA;" OwnerUserId="4068" LastEditorUserId="4068" LastEditDate="2015-10-03T15:56:22.983" LastActivityDate="2015-10-03T15:56:22.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21571" PostTypeId="2" ParentId="21568" CreationDate="2015-10-03T15:34:32.847" Score="8" Body="&lt;p&gt;When holding, it is true that you should take then inbound wind correction and multiply it by three and use that for the outbound correction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question centers on what happens if you don't know the correct wind information and obstacle clearance.  Fortunately for us, the FAA has given us a wide obstacle clearance area for the holds.  While it is important to stay on the protected side of the hold, if you find yourself on the unprotected side of the hold, you are still &quot;protected&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture taken from &lt;a href=&quot;http://forums.jetcareers.com/threads/holding-pattern-protected-area.80377/&quot; rel=&quot;noreferrer&quot;&gt;http://forums.jetcareers.com/threads/holding-pattern-protected-area.80377/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WrO44.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WrO44.png&quot; alt=&quot;Holding Pattern Obstacle Clearance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is to fly the correct entry procedure and it will help to ensure you stay within the obstacle clearance protected area.  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A direct entry requires passing the holding point and immediately turning to the outbound leg.  You may not know the wind correction so fly the outbound heading.  Upon turning inbound get back onto your inbound course and try to determine your wind correction angle&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;A parallel entry requires passing the holding point and tracking outbound on the radial.  You should be able to figure out your wind correction.  Turn 180° + 45° to re-intercept the inbound course.  At this point, you should have a good idea where the wind is coming from.&lt;/li&gt;&#xA;&lt;li&gt;A teardrop entry requires passing the holding point and turning 30° into the protected side.  When you turn inbound, there should be enough time to figure out what the winds are doing.&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If the winds are constantly changing, do your best to stay on the protected side of the hold, if you venture a little to the unprotected side, you are still covered.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-03T15:34:32.847" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21572" PostTypeId="2" ParentId="21568" CreationDate="2015-10-03T15:44:30.447" Score="9" Body="&lt;p&gt;One you are established inbound on the VOR radial note the heading you are flying to maintain that course. The difference between that and the radial is your wind correction angle. Multiply it by 3 and apply it to the outbound course heading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To do this you don't need to know anything about the wind.  You just need to be able to intercept and track the inbound radial. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can repeat this every inbound leg so if the winds are changing you can update your correction every 4 minutes and you always know you are on course one of ever four minutes. With the generous obstacle protection area even small errors will not compromise safety. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-10-03T15:44:30.447" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21574" PostTypeId="2" ParentId="8471" CreationDate="2015-10-03T19:12:08.870" Score="-5" Body="&lt;p&gt;The &quot;line&quot; about needing full power for takeoffs and landings is true. I was taking courses for an Airframe &amp;amp; Powerplant certification for airplane mechanics. According to professors at what used to be the Northrop Rice School of Aviation Technology in Los Angeles, California, all power in an airliner is diverted to the engines for maximum thrust on takeoff. That means the lights are turned off or dimmed and even the air conditioning is turned off until after takeoff. As we all know, the airplanes are getting bigger and bigger. However, the length of the airport runways has not changed much at most of the airports. That means that the pilots of these jumbo jets have to get up to their airplane's noted speed for takeoff faster (before they run out of runway). So all &quot;redundant&quot; systems on an aircraft are shut down so that power can be used to get that airplane off the ground safely in the distance they have to get lift. Flying is all about the power to weight ratio on any aircraft. But the jumbo jets require a much higher speed to be able to take off.&lt;/p&gt;&#xA;" OwnerUserId="11558" LastActivityDate="2015-10-03T19:12:08.870" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21577" PostTypeId="1" AcceptedAnswerId="44188" CreationDate="2015-10-04T02:54:14.367" Score="8" ViewCount="12358" Body="&lt;p&gt;I'm trying to understand the differences here between an autopilot that is &quot;coupled&quot; into a GPS/NavCom like a Garmin 530W and what GPSS and altitude hold (like in an S-TEC 50 autopilot) have to do with this. Can anyone explain this to me? Maybe there is no difference, I really need this explained. &lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="19" LastEditDate="2017-01-25T10:39:42.887" LastActivityDate="2017-12-31T22:07:38.857" Title="What are the differences between a GPS coupled autopilot and a GPSS autopilot?" Tags="&lt;navigation&gt;&lt;instrument-flight-rules&gt;&lt;autopilot&gt;&lt;gnss&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21578" PostTypeId="1" CreationDate="2015-10-04T03:26:15.000" Score="5" ViewCount="752" Body="&lt;p&gt;So the 1500 hour legislation was set to expire on the 30th of September 2015. Anyone know the outcome of the expiration. Did congress extend the rule, or is it no longer in effect. I tried searching the web but couldn't find any info. &lt;/p&gt;&#xA;" OwnerUserId="11356" LastEditorUserId="1696" LastEditDate="2017-01-20T15:54:26.490" LastActivityDate="2017-01-20T15:54:26.490" Title="Did the 1500 hour rule expire?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21579" PostTypeId="2" ParentId="21577" CreationDate="2015-10-04T03:33:39.977" Score="4" Body="&lt;p&gt;An autopilot in NAV mode, using GPS as a source (GN*430+), will do the same thing as an autopilot using GPSS directly from a GPS (for example, KLN89/90 or GPS155XL).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPSS is, as I understand it, a holdover from the time when panel-mount IFR-approved GPS units were standalone. GPSS was the way to feed your autopilot course correction data from that dedicated device. When the Garmin GNS430 hit the market and utterly destroyed the competition, GPS/NAV/COM became the standard, and the GPS or CDI control determined what the data was going to the autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft you get into odd situations where a newer panel is paired with an older autopilot. I have a fair bit of time in an &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2005/November/1/Tiger-Aircraft-AG-5B-Tiger&quot; rel=&quot;nofollow&quot;&gt;AG-5B Tiger with G1000&lt;/a&gt;, and it has the S-Tec System 30 autopilot with a GPSS module. I never understood this setup, as the System 30 has low/high VOR/LOC/GPS tracking built in. The GPSS module was completely redundant and seemed to be a holdover from the pre-G1000 model of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Source: personal experience, made more certain via &lt;a href=&quot;http://forums.avidyne.com/forum_posts.asp?TID=290&amp;amp;title=dfc90-gpss-vs-nav-mode&quot; rel=&quot;nofollow&quot;&gt;this thread on the Avidyne forums&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2015-10-04T03:40:01.250" LastActivityDate="2015-10-04T03:40:01.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21580" PostTypeId="2" ParentId="21578" CreationDate="2015-10-04T04:15:50.963" Score="3" Body="&lt;p&gt;&lt;strong&gt;The 1500 hour rule is still in effect.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule wasn't set to expire on the 30th of September; &lt;strong&gt;technically &lt;em&gt;the entire FAA was going to expire&lt;/em&gt;.&lt;/strong&gt; Congress &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/July/01/FAA-reauthorization-bill-delayed&quot; rel=&quot;nofollow&quot;&gt;votes on the authorization for the FAA to regulate air transportation&lt;/a&gt;; that authorization was set to expire 30 September, 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/September/28/House-passes-FAA-funding-extension&quot; rel=&quot;nofollow&quot;&gt;The House voted to authorize funding on 28 September&lt;/a&gt; while the Senate &lt;a href=&quot;http://www.postbulletin.com/news/politics/congress-votes-to-renew-faa-authority-for-months/article_0ddbf55a-c615-56ad-bb2d-b2c7453ebff1.html&quot; rel=&quot;nofollow&quot;&gt;passed a 6-month extension on 29 September&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Expect to see similar discussions in 6 months.&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-10-04T04:15:50.963" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21581" PostTypeId="2" ParentId="12109" CreationDate="2015-10-04T06:51:18.063" Score="3" Body="&lt;p&gt;The passenger jet engine mounts (pylons) are designed to break away due to excessive vibration (a type of engine failure) because you would rather drop an engine than have your wing break off and drop like a brick.&lt;/p&gt;&#xA;" OwnerUserId="11565" LastEditorUserId="1467" LastEditDate="2015-10-04T06:59:38.040" LastActivityDate="2015-10-04T06:59:38.040" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21583" PostTypeId="2" ParentId="17206" CreationDate="2015-10-04T11:25:58.730" Score="3" Body="&lt;p&gt;I assume you talk about the airfoil's nose, not the fuselage nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pointed nose will cause flow separation in subsonic flow if the angle of attack is only slightly different from the angle of the leading edge. This flow separation will mightily increase drag because now no suction peak at the nose will develop. This suction peak is causing what is sometimes called &quot;&lt;a href=&quot;http://www.pdas.com/refs/tp1500.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;leading edge thrust&lt;/a&gt;&quot; (PDF!). Without it, the aerodynamic forces will act in a direction orthogonal to the wing's surface and not (almost) orthogonal to the flow direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In pure supersonic flow the pointed leading edge is superior, because it causes less wave drag. However, it is preferable to &lt;a href=&quot;https://aviation.stackexchange.com/questions/4992/why-are-swept-wings-better-for-breaking-the-sound-barrier&quot;&gt;sweep the wing&lt;/a&gt; such that the flow around the leading edge will stay subsonic even in supersonic flight, precisely because it still allows leading edge thrust to manifest itself.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-04T11:25:58.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21584" PostTypeId="1" AcceptedAnswerId="21585" CreationDate="2015-10-04T12:21:01.063" Score="7" ViewCount="1199" Body="&lt;p&gt;When I was young my father opened a ship equipment shop. He purchased the broken airliners wheel and resell to the ship operators as anti-crash barrier on ship or in the pier like in the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J1pwB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J1pwB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the other parts in airliners be used after life cycle?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-10-04T13:51:27.840" Title="How are different parts of airliners handled after the end of life-cycle?" Tags="&lt;airliner&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-05T16:46:46.970" ContentLicense="CC BY-SA 3.0" />
  <row Id="21585" PostTypeId="2" ParentId="21584" CreationDate="2015-10-04T13:37:48.593" Score="10" Body="&lt;p&gt;Various parts of the airliners face different fates once it has been &lt;a href=&quot;http://aviationweek.com/blog/photos-what-happens-all-those-airliners-when-they-retire-see-tear-down-747-400&quot; rel=&quot;noreferrer&quot;&gt;decided to breakup the aircraft&lt;/a&gt;. Most of the parts are &lt;a href=&quot;http://jalopnik.com/5569874/how-to-recycle-an-airplane/&quot; rel=&quot;noreferrer&quot;&gt;reused in one way or the another&lt;/a&gt;. The dismantling of the aircraft starts after removal of hazardous liquids and radioactive components.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engines- Usually, the aircraft and engines will be at different stages of their lives. The engines are removed and sold for operating in other aircraft. In case the engine life is also considered over, either its components will be used for spare parts or it too will be scrapped for materials.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yEetX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yEetX.jpg&quot; alt=&quot;Engine removal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: jalopnik.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Avionics- The avionics components are usually valuable and are removed for use in other aircraft. Since they are line replaceable units anyway, this should pose no problem.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1yyRR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1yyRR.jpg&quot; alt=&quot;Stripped 747-400 Cokpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stripped down cockpit of 747-400; Image from aviationweek.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Interior- The interior of the aircraft, like the seats, entertainment systems are stripped and sold off. Items in the galley (like coffee makers), the air-conditioning systems also face the same fate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qWIny.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qWIny.jpg&quot; alt=&quot;747-400 cabin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stripped cabin of 747-400; Image from aviationweek.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Some items like the APU, actuators, landing gear, pipings, etc, if they have life are removed and sold for use in other aircraft (after appropriate checks and certification).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case the aircraft has removable winglets, they are removed as well, for re-use.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Any hazardous materials like composites, depleted Uranium (used as counterweights in 747s, 727s etc.) are removed and disposed off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft (structure) is then cut to pieces and metal parts are melted and reforged for reuse in industries, with unusable parts finding its way to landfill.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PuHvH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PuHvH.jpg&quot; alt=&quot;Cut-down aircraft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: tarmacaerosave.aero&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following figure from ICAO report Aircraft End-of-Life: Scrapping and Recycling shows how the materials are reused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/15OwY.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/15OwY.png&quot; alt=&quot;Aircraft material re-use&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;What's new in aircraft materials recycling?&lt;/em&gt; ICAO workshop presentation&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, stripping down and recycling of aircraft involves millions of dollars and is highly efficient, with over 90% reuse of materials being quoted. It remains to bee seen what happens to material reclamation as more and more aircraft components are made from composites.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-04T13:51:27.840" LastActivityDate="2015-10-04T13:51:27.840" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21587" PostTypeId="2" ParentId="21470" CreationDate="2015-10-04T15:28:12.927" Score="2" Body="&lt;p&gt;On top of &lt;a href=&quot;https://aviation.stackexchange.com/a/21503/9999&quot;&gt;Samis answer&lt;/a&gt; above, I'd like to add that there are also different requirements for the content (at least in europe): &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The life-vest demo is only required if extended portions of the flight are over water and/or climb and approach routes lead over water. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The safety demo has to be finished before take-off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I remember quite a number of flights where we had to wait at the holding point because the cabin was not yet ready.&lt;/p&gt;&#xA;" OwnerUserId="9999" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-10-04T15:28:12.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21588" PostTypeId="2" ParentId="21535" CreationDate="2015-10-04T15:35:05.650" Score="2" Body="&lt;p&gt;Turbine is turbine.  If you burn fuel to spin a turbine that drives a compressor, it's turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I counted all turboshaft time as &quot;turbine&quot; when reviewing resumes for pilot applicants.  Understanding the theory behind turbine engine operation is what everyone cares about, whether is was a turbo-this or a turbo-that is not as important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contact a few insurance brokers just to be sure.  Falcon Insurance, AOPA, TrueCourse just to name a few.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2015-10-04T15:35:05.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21589" PostTypeId="1" AcceptedAnswerId="21596" CreationDate="2015-10-04T15:57:36.423" Score="6" ViewCount="1003" Body="&lt;p&gt;A friend of mine owns a flight school in the states.  A Designated Pilot Examiner (DPE) has informed his staff that a new TSA regulation will require all new prospective flight students to meet with a DPE prior to starting any flight training.  That is, every new student will need permission from a government agent prior taking a flight lesson from any flight school (61 or 141).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would typically dismiss this as nonsense but, considering he source of the info is a DPE, I'm curious to know if there is any truth behind this rumor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the TSA plan to implement rules that require every prospective student to seek pre-approval from a government agent (not just a flight school) prior to beginning flight training?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current regulations require the flight school, or independent CFI as the case may be, to verify citizenship and retain records.  This can be done in minutes.  The DPE indicates that appointments are required and additional fees assessed for the new layer of government approval.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say it ain't so!&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="19" LastEditDate="2017-03-03T08:20:52.157" LastActivityDate="2017-03-03T13:19:37.727" Title="Is a new type of TSA pre-approval required before commencing flight training?" Tags="&lt;faa-regulations&gt;&lt;security&gt;&lt;tsa&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21590" PostTypeId="1" AcceptedAnswerId="21591" CreationDate="2015-10-04T16:00:00.223" Score="0" ViewCount="378" Body="&lt;p&gt;The current record for &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_distance_record#Commercial_aircraft&quot; rel=&quot;nofollow&quot;&gt;longest commercial flight&lt;/a&gt; is 21,602.22km by Boeing 777-200LR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the designed maximum range for B777-200LR is &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777#Specifications&quot; rel=&quot;nofollow&quot;&gt;15,800 km&lt;/a&gt;. So how is this possible?&lt;/p&gt;&#xA;" OwnerUserId="1416" LastActivityDate="2015-10-04T18:21:20.083" Title="How can a plane fly far longer than designed?" Tags="&lt;commercial-operations&gt;&lt;range&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2015-10-04T19:28:07.053" ContentLicense="CC BY-SA 3.0" />
  <row Id="21591" PostTypeId="2" ParentId="21590" CreationDate="2015-10-04T16:13:30.090" Score="4" Body="&lt;p&gt;The design range is fully loaded.  This flight had 35 passengers, no cargo, full fuel and was run as a project and flown by a test pilot.  It was not a commercial flight in the meaning that most people would recognise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They had to wait for weeks until the winds aloft, especially the jet stream, were at their most advantageous.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-10-04T16:13:30.090" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21592" PostTypeId="2" ParentId="13037" CreationDate="2015-10-04T16:14:27.103" Score="48" Body="&lt;p&gt;Some very spot-on comments, some comments that are totally ignorant of the job. I am a retired ATC, 32 years.  I worked at one of the world's busiest and most complex US facilities (as described by many independent sources).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have you ever:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Heard a family on the other end of the radio screaming just moments before they were obliterated in the air by a military fighter flying VFR? &lt;/li&gt;&#xA;&lt;li&gt;Tried in vain to find a way to contact the occupants of Payne Stewart's jet only to watch helplessly as it finally crashes after several hours of flight?&lt;/li&gt;&#xA;&lt;li&gt;Had 30+ airliners in your sector which happens to be dotted with Level 5 thunderstorms?  The amount of airspace you now have has decreased substantially and the aircraft all need to deviate. They all want to either go in different directions, or they all want to head towards the few clear spots left. You sit there for 2 hours directing aircraft to basically thread a needle at 500mph and pulling out every trick in your book to ensure that there is enough space to ensure all 30+ aircraft (and more, because those aircraft never stop coming) make it through your airspace without encountering the dangers of severe weather or coming into physical contact with another aircraft. Aircraft that are often executing movements that they don't have clearance for, which requires quick and accurate reaction from the controller.&lt;/li&gt;&#xA;&lt;li&gt;Dealt with one of the times when a corporate jet &quot;flames out&quot; at 43,000 feet and immediately descends through a dozen or more jets flying the same path, requiring the controller to immediately clear all of those aircraft out of the path of that corporate jet.&lt;/li&gt;&#xA;&lt;li&gt;Had a small twin prop lose all electronics and be unable to navigate properly while in a thick cloud layer.  His portable radio is not working properly, so radio communications must be short and accurate. (Remember, you have another sector full of aircraft that you are also providing services to). Finally, his portable radio fail.  Right before that, you ask the pilot if he has a cell phone. He does.  You give him a phone number and you and he are able to communicate via telephone to finally guide him to a safe landing at Newport News Airport.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I could write a book about many specific events that controllers have experienced.  The &quot;pucker factor&quot; events.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the real stress is the long term chronic stress that the job presents.&#xA;Certainly, there are facilities that are both low traffic and have uncomplicated operations. If you are lucky enough to work at one of these (and willing to accept the low end of the pay scale) then stress is probably much lower and stressful events infrequent.  But for the majority of controllers (who work at a number of very high traffic facilities; air traffic in the US is higher and more complicated than the next 29 countries' air traffic, combined) the stress is a chronic, continuous level (not the big adrenalin-pumping situations) from being attached to your position for several hours, trying to maintain a constant &quot;big picture&quot;, maintaining situational awareness, issuing control instructions to ensure that SAFETY is always the first product of your efforts.  Many, if not most, controllers will most likely retire with high blood pressure, diabetes, sleep disorders, etc. that despite best efforts to exercise and live a healthy lifestyle will probably affect a controller for the remainder of their life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certainly, other jobs are stressful, and I would never try to compare one as &quot;more stressful&quot; than the other.  The top ones are all stressful.  But those that try to downplay the stress of air traffic control would only need to visit a busy air traffic control facility for a day and they would see and probably feel the stress themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a very good friend that is an FBI field agent in Washington, DC.  He has worked on some very high-profile cases.  We were talking one day and he said something about the stress of air traffic control.  I chuckled saying that at least I wasn't being faced by some of the most dangerous people in the country. But his response was that in his job they have detailed plans for what they do.  His raids were in the middle of the night when these people were asleep and unsuspecting.  He had a well-trained team that each had specific responsibilities.  They had plenty of firepower and protective equipment.  He said that most of his operations were quite easy and they experienced little resistance. He did have moments of intensity, but he (who had visited an air traffic facility) did not think the stress he experienced was anywhere near to what he saw at the air traffic control facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I still would not want to be a law enforcement officer, nor a school teacher for that matter!  My personality was a good match for the job of air traffic control.  But now that I am retired, I take blood pressure medicine, am borderline diabetic despite a regular exercise program and am within a healthy weight and eat very healthy.  I also still have sleep apnea and other sleep issues that I see a sleep doctor several times a year for.  All of my present health issues, which are well-controlled, are according to the doctors a direct effect of the stresses of being an air traffic controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air traffic control IS stressful.  Is it more stressful than other jobs? I doubt it. And to argue about whose job is more stressful is a silly exercise. The trick is having a personality that meshes with the job.  If you are in a job that is not a good match, that is stressful.&lt;/p&gt;&#xA;" OwnerUserId="11571" LastEditorUserId="69" LastEditDate="2017-05-17T15:14:22.180" LastActivityDate="2017-05-17T15:14:22.180" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21593" PostTypeId="1" CreationDate="2015-10-04T16:15:13.097" Score="4" ViewCount="734" Body="&lt;p&gt;Is there any study showing how probabilities of various kinds of aviation (e.g. crash-landings, fatal crashes, mid-air collisions) accidents have increased or reduced over time?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="11411" LastEditDate="2015-10-05T18:11:25.153" LastActivityDate="2015-10-05T18:11:25.153" Title="What are the statistical probabilities of commercial aircraft accidents?" Tags="&lt;aviation-history&gt;&lt;accident-statistics&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21594" PostTypeId="1" CreationDate="2015-10-04T17:04:24.103" Score="4" ViewCount="3050" Body="&lt;p&gt;This is a questions about fixed-wing aircraft in general -- commercial planes and smaller. I have seen on &lt;a href=&quot;https://www.youtube.com/watch?v=YKax-31UCQM&quot; rel=&quot;nofollow&quot;&gt;a video&lt;/a&gt; that planes are capable of flying in a holding pattern with an nose-down attitude &quot;for greater passenger comfort&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what are the advantages and disadvantages of level flight (not descent) with a nose down attitude? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And for what reasons do pilots fly like this?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="11411" LastEditDate="2015-10-04T18:37:47.053" LastActivityDate="2015-10-04T18:37:47.053" Title="What are the advantages and disadvantages of level flight with a nose-down attitude?" Tags="&lt;fixed-wing&gt;&lt;attitude&gt;&lt;pitch&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-10-04T22:59:31.247" ContentLicense="CC BY-SA 3.0" />
  <row Id="21595" PostTypeId="2" ParentId="21593" CreationDate="2015-10-04T17:24:06.047" Score="5" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Air_Transport_Association&quot; rel=&quot;nofollow noreferrer&quot;&gt;International Air Transport Association&lt;/a&gt; (IATA) publishes each year a report about aircraft accidents in the world. The latest one indicates these average figures:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There are 3.3 billion passengers per year.&lt;/li&gt;&#xA;&lt;li&gt;There are 100,000 flights per day.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Over the last four years the accident rate decreased from 94 to 73 accidents per year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2014, among these 36,500,000 flights:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There has been a total of 73 accidents&lt;/li&gt;&#xA;&lt;li&gt;12 accidents had fatalities (641 fatalities).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Extracts from &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/3049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA 2015 report&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gxVIP.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gxVIP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/3049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA report&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Period 2010-2014&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/avlDl.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/avlDl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/3049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA report&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Type and fatalities&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zw5U0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zw5U0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/3049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA report&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Geographical distribution&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EoEyy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EoEyy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/3049.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA report&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-10-05T05:34:49.093" LastActivityDate="2015-10-05T05:34:49.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21596" PostTypeId="2" ParentId="21589" CreationDate="2015-10-04T17:55:28.377" Score="8" Body="&lt;p&gt;(Answer completely rewritten based on new information)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Does the TSA plan to implement rules that require every prospective student to seek pre-approval from a government agent (not just a flight school) prior to beginning flight training?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not exactly. US citizens can still start flight training whenever they want. But from April 1, 2016 pre-approval from &quot;a government agent&quot; (the TSA) is required prior to soloing. Foreigners will still need TSA approval before starting flight training.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The final rule on this has now been &lt;a href=&quot;https://www.gpo.gov/fdsys/pkg/FR-2016-01-12/pdf/2016-00199.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;published in the Federal Register&lt;/a&gt; and the TSA will indeed vet all student pilots, as of 1 April 2016 (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This action requires  applicants to apply for a student pilot &#xA;  certificate through a Flight Standards  District Office, designated&#xA;  pilot  examiner, airman certification  representative associated with&#xA;  a pilot  school, or certified flight instructor.  Aviation Medical&#xA;  Examiners will no  longer issue a combination medical  certificate and&#xA;  student pilot certificate.  Student pilot certificates will be issued &#xA;  on the same medium as other pilot  certificates and will have no&#xA;  expiration  date. All student pilot certificates issued  before the&#xA;  effective date of this final rule  will expire according to their&#xA;  terms  unless they are replaced by another  pilot certificate. &lt;strong&gt;This&#xA;  final rule responds  to section 4012 of the Intelligence  Reform and&#xA;  Terrorism Prevention Act  and facilitates security vetting by the &#xA;  Transportation Security Administration  of student pilot applicants&#xA;  prior to  certificate issuance&lt;/strong&gt;. This action  withdraws the proposal&#xA;  for pilot  certificates to include a photograph of  the individual&#xA;  pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But note that a student pilot's license is still not required in order to start training, it's only required in order to solo. So under this new rule, a US citizen can start flight training as usual, but can't solo until he gets TSA approval for his student pilot application:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;IRTPA [the Intelligence Reform and &#xA;  Terrorism Prevention Act] required that security vetting  of all individuals, including&#xA;  pilots, must  be successfully completed by TSA  before the FAA issues&#xA;  a certificate.  Therefore, applicants for student pilot  certificates&#xA;  must be vetted to receive  their certificates and operate an aircraft &#xA;  as pilot in command.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This also means that AMEs will no longer issue student certs, only medical certificates. The FAA expects that processing will take several weeks, which may be an issue for accelerated training programs that aim to get you a full pilot's license in a month or less:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA estimates that the  turnaround time for student pilot &#xA;  certificates can be reduced to an average  of 3 weeks or less,&#xA;  provided that initial  security vetting by TSA indicates that  the&#xA;  applicant is eligible for the  certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There was also some concern that it wouldn't be possible for pilots to solo on their 16th birthday any more because of the processing time, but the FAA &lt;a href=&quot;http://fsims.faa.gov/wdocs/notices/n8900_371.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;specifically addressed that point&lt;/a&gt;, essentially by asking students to submit their application well in advance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the 'plus' side, the new regulation specifically says that pilots licenses will still not have a photograph (at least for now), which would have added more time and costs to the whole process. And the new student certificates will be plastic, not paper.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2017-03-03T13:19:37.727" LastActivityDate="2017-03-03T13:19:37.727" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21597" PostTypeId="2" ParentId="21594" CreationDate="2015-10-04T18:07:01.060" Score="12" Body="&lt;p&gt;Generally, a slight nose-up attitude gives the best performance. This allows the fuselage to create some lift without producing too much drag, thus filling the drop in the spanwise lift distribution created by the interruption of the wing by the fuselage. However, in passenger aircraft this will make the job of attendants much harder because their trolleys need to be pushed uphill and will roll away when not secured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, a neutral attitude is preferred in cruise. When the aircraft slows down, it needs to increase its angle of attack, so the nose-up attitude results. When flaps are deflected, the zero-lift angle of attack is reduced, so a smaller angle of attack will again be possible. The precise attitude is a side effect of speed, air density and flap settings, and is not deliberately controlled when flying a holding pattern. By this time the flight attendants have returned to their jump seats, anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that some aircraft will fly a nose-down attitude by design. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot; rel=&quot;noreferrer&quot;&gt;Boeing B-52&lt;/a&gt; has powerful flaps which are designed to allow it to lift off without rotating, and when the aircraft accelerates during the initial climb after take-off or flies its approach, the fuselage will have a nose-down attitude. See the picture below of the B-2, the B-1B and the B-52 all flying at the same speed, each with its own fuselage attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xgkHo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xgkHo.jpg&quot; alt=&quot;B-2, B-1B and B-52 flying at the same speed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-2, B-1B and B-52 flying at the same speed (picture &lt;a href=&quot;http://fimv.narod.ru/misc/04163bombrs.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-04T18:07:01.060" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21598" PostTypeId="2" ParentId="21590" CreationDate="2015-10-04T18:21:20.083" Score="0" Body="&lt;p&gt;The designed maximum range is just a number, it is affected by a number of constrained factor like fuels and payload as wells as unconstrained factor like jet-steam. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9Afsa.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Afsa.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-10-04T18:21:20.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21599" PostTypeId="1" CreationDate="2015-10-04T19:43:09.803" Score="4" ViewCount="6660" Body="&lt;p&gt;Statistically speaking, how reliable are Lycoming and Continental general aviation piston engines? What I'd really like to either find or build is a table showing the probability of experiencing engine failure on a properly-maintained piston engine for most of the common models of engine. Is the data out there?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-06T06:00:26.433" Title="How reliable are Lycoming and Continental general aviation piston engines?" Tags="&lt;piston-engine&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21600" PostTypeId="1" AcceptedAnswerId="21605" CreationDate="2015-10-04T20:51:13.403" Score="4" ViewCount="2540" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/asbYtm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/asbYtm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/fEr7Mm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fEr7Mm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://materialsengineeringconsultant.com&quot; rel=&quot;noreferrer&quot;&gt;materialsengineeringconsultant.com&lt;/a&gt; and &lt;a href=&quot;http://initious.blogspot.com&quot; rel=&quot;noreferrer&quot;&gt;initious.blogspot.com&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the engines are circular except for some that are oval. The oval shape provides a better ground clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why aren't the intakes square-shaped? Is there some aerodynamic reason for the circular / oval intake shape?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="14897" LastEditDate="2018-06-27T16:16:31.730" LastActivityDate="2018-06-27T16:19:19.970" Title="Why are turbofan inlets circular- or oval-shaped instead of square-shaped?" Tags="&lt;turbofan&gt;&lt;engine-design&gt;&lt;inlet&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21601" PostTypeId="2" ParentId="21600" CreationDate="2015-10-04T22:09:52.433" Score="13" Body="&lt;p&gt;Airliner jet intakes are round because the engines are round, and for subsonic flight that's all you need - it's easy and cheap to engineer, provides a clean airflow for the engine and unlike some other shape doesn't present unnecessary frontal area that will only cause drag. You've already identified ground clearance as the reason for a flattened shape on some installations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ah, you say, what about Concorde or the Tu144?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oWtnj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oWtnj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.hitechweb.genezis.eu&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.hitechweb.genezis.eu&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that I specified 'subsonic'. Once one reaches supersonic speeds the requirements change. The intake is crucial in controlling airflow into the engine, reducing it's speed to a subsonic level so that the engine can operate efficiently. It's far easier to engineer the required flaps and baffles around a rectangular intake than to do the same with a circular one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the different intake configurations for Concorde at (A) Take-off, (B) Supersonic cruise and (C) Reverse Thrust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sS3yy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sS3yy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By Nubifer (Own work) [CC0], via Wikimedia Commons)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is just as true of air intakes on supersonic military aircraft. You'll notice that almost all supersonic military aircraft use some variation of rectangular intakes for this reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with all things aeronautical, there are exceptions. The English Electric Lightning,  Mig-21 and the SR-71 (and numerous others) use circular intakes with the geometry adjusted by a movable inlet cone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll find a more detailed discussion of supersonic intakes in &lt;a href=&quot;https://aviation.stackexchange.com/a/13109/11516&quot;&gt;this answer&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kZMKEm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kZMKEm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sa9vqm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sa9vqm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;MiG-21 RB23&quot;. Licensed under CC BY-SA 3.0 via Commons - &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MiG-21_RB23.JPG#/media/File:MiG-21_RB23.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/wiki/File:MiG-21_RB23.JPG#/media/File:MiG-21_RB23.JPG&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Lockheed SR-71 Blackbird&quot; by Judson Brohmer/USAF - NASA Website Licensed under Public Domain via Commons - &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Lockheed_SR-71_Blackbird.jpg#/media/File:Lockheed_SR-71_Blackbird.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/wiki/File:Lockheed_SR-71_Blackbird.jpg#/media/File:Lockheed_SR-71_Blackbird.jpg&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorUserId="14897" LastEditorDisplayName="user11516" LastEditDate="2018-06-27T16:19:19.970" LastActivityDate="2018-06-27T16:19:19.970" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21602" PostTypeId="1" CreationDate="2015-10-04T22:46:36.977" Score="1" ViewCount="959" Body="&lt;p&gt;I am C++ enthusiast and I like to design and architecture my software with latest C++ features specially with &lt;em&gt;templates&lt;/em&gt;,  but I have been struggling hard to find a way.&lt;/p&gt;&#xA;&lt;p&gt;The compiler we use for LynxOS-DO178 RTOS with PowerPC architecture is more than decade old, with poor optimization, lack of several features, and often times just ending up in &amp;quot;internal compiler error&amp;quot;. Code bloating occurs with simple template instantiations, which could be easily remove with latest compilers.&#xA;All ideas and innovative improvements are simply stopped by the fact that our compiler cannot support &lt;em&gt;this&lt;/em&gt; and &lt;em&gt;that&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;p&gt;I believe I could get a tool chain for my cross-platform development supporting somewhat latest versions of GNU GCC/G++. But not sure if that can be ever certified for DAL A SW.&lt;/p&gt;&#xA;&lt;p&gt;We have now C++14, approaching to C++17, still I have this question do we have anything modern yet from C++ that sees &amp;quot;light of sun&amp;quot; on a critical SW ?&#xA;What are the risks, cons, etc for a flight critical SW ?&lt;/p&gt;&#xA;&lt;p&gt;Bjarne Stroustrup recently announced &lt;a href=&quot;https://github.com/isocpp/CppCoreGuidelines&quot; rel=&quot;nofollow noreferrer&quot;&gt;core C++ guidelines&lt;/a&gt;, that resolves around use of modern C++11/14 and templates, but can we ever use those on Flight DAL A SW ?&lt;/p&gt;&#xA;&lt;p&gt;&lt;sub&gt;&lt;em&gt;Not sure if this a right platform to discuss this, if someone knows a better platform please direct me to that.&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="3354" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-03-14T09:49:14.940" Title="Is there's any risk using modern C++ compiler on DAL A Display Application Flight Software?" Tags="&lt;software&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ClosedDate="2015-10-05T12:55:05.397" ContentLicense="CC BY-SA 3.0" />
  <row Id="21603" PostTypeId="1" AcceptedAnswerId="21606" CreationDate="2015-10-04T22:48:17.493" Score="6" ViewCount="4458" Body="&lt;p&gt;I was listening to some &lt;a href=&quot;https://youtu.be/biDnVJ6EqA8?t=8m41s&quot; rel=&quot;nofollow&quot;&gt;[REAL ATC] MD-80 DELTA CRASH at LaGuardia Airport&lt;/a&gt; and noticed something just after 8:41. My question isn't about the accident, but actually about a request to the LaGuardia Tower from Tug1 (or Truck1, it's not clear, although the CC calls it Tug1 it sounds like Truck1) where the tug asks &quot;Tug1 at company, we can cross Papa?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the term &lt;em&gt;company&lt;/em&gt; is used during ATC communications to tell one plane of a company (such as American Airlines) that they are talking about another airplane from the same company.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But how can a Tug/Truck be referring to a place as company?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="1696" LastEditDate="2018-04-10T02:50:33.693" LastActivityDate="2018-04-10T02:50:33.693" Title="How can a tug be referred to as company?" Tags="&lt;air-traffic-control&gt;&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21604" PostTypeId="2" ParentId="17024" CreationDate="2015-10-04T22:52:51.430" Score="0" Body="&lt;p&gt;What about 'Iron Bridge'?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Sunset_at_Ironbridge.jpg/1280px-Sunset_at_Ironbridge.jpg&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Sunset_at_Ironbridge.jpg/1280px-Sunset_at_Ironbridge.jpg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/9/98/Sunset_at_Ironbridge.jpg/1280px-Sunset_at_Ironbridge.jpg&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/The_Iron_Bridge&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;joints were similar to what a carpenter would use.  So using traditional method for a new material, iron.  They seem to be doing the same with carbon fiber. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bbc.co.uk/history/british/victorians/iron_bridge_01.shtml&quot; rel=&quot;nofollow&quot;&gt;http://www.bbc.co.uk/history/british/victorians/iron_bridge_01.shtml&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time lapse videos of 787 show riveting for the main fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/SJZk9vNS8NE?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="11576" LastEditorUserId="5517" LastEditDate="2015-10-05T17:16:55.703" LastActivityDate="2015-10-05T17:16:55.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21605" PostTypeId="2" ParentId="21600" CreationDate="2015-10-04T22:58:44.333" Score="12" Body="&lt;p&gt;The main purpose of having a square inlet is to have an oblique shock at the entrance so as to decelerate the air to subsonic speed before reaching the compressor. Also, the square inlet ramps are adjustable to produce optimum shock systems over a wide speed ranges. However, they are quite complicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbofans used in civil airliners operate at subsonic speeds and don't require any shocks for flow deceleration. The circular shape is the best for getting maximum amount of undisturbed airflow into the engine, especially the bypass section. The inlets of high bypass turbofan engines are simple, straight and short with a thick lip.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-04T22:58:44.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21606" PostTypeId="2" ParentId="21603" CreationDate="2015-10-05T00:15:44.890" Score="8" Body="&lt;p&gt;I just saw BowlOfRed's comment, and listened to it again and I could make it out this time as &quot;Tug 1 and Company&quot;. So, basically, when used with vehicles, using &quot;and company&quot; will often indicate that there's more than one vehicle in the group(or possibly aircraft in tow), and whoever's being addressed is in charge of talking for them. Just like when a flight of aircraft is flying or taxing, whoever's talking for the flight, that callsign is used for the whole group.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For other examples of &quot;and company&quot;: During snowplow operations, usually you'll just have 1 driver in a group talking to Ground/Tower for that group, and they're also in charge of reporting when all their group is clear of runways or other movement areas. Other times, it's when airport operations is escorting(via vehicle) other vehicles on the airport, from survey crews to construction crews.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-10-05T00:15:44.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21607" PostTypeId="1" AcceptedAnswerId="21610" CreationDate="2015-10-05T00:53:16.693" Score="3" ViewCount="5773" Body="&lt;p&gt;Is it permissible for an aircraft to fly without red, green, and white strobe position lights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible for any aircraft to legally fly with only a solid white or solid red light on the underbelly?&lt;/p&gt;&#xA;" OwnerUserId="2016" LastEditorUserId="19" LastEditDate="2016-10-31T11:57:14.507" LastActivityDate="2016-10-31T11:57:14.507" Title="Is it legal to fly an aircraft with no navigation beacons, and only solid lighting?" Tags="&lt;usa&gt;&lt;aircraft-lighting&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21608" PostTypeId="2" ParentId="21607" CreationDate="2015-10-05T01:05:41.213" Score="0" Body="&lt;p&gt;I'm not sure if aircraft has any navigational beacon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The red and white (strobe)  lights are anti collision lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/#manuals&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Information Manual(AIM)&lt;/a&gt;, 4−3−23. Use of Aircraft Lights,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft anti−collision light system can use one or more rotating beacons and/or strobe lights, be colored either red or white, and have different (higher than minimum) intensities when compared to other aircraft. Many aircraft have both a rotating beacon and a strobe light system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Usually, the anti-collision/position lights are to be operated during night flying. From the same manual: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft position lights are required to be lighted on aircraft operated on the surface and in flight from sunset to sunrise. In addition, aircraft equipped with an anti−collision light system are required to operate that light system during all types of operations&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, the pilot can turn them off if there are safety concerns.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, during any adverse meteorological conditions, the pilot−in−command may determine that the anti−collision lights should be turned off when their light output would constitute a hazard to safety&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In your case, the pilot may have turned off the anti-collision lights and operated only the position lights.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-05T01:05:41.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21609" PostTypeId="2" ParentId="17374" CreationDate="2015-10-05T01:12:26.220" Score="1" Body="&lt;p&gt;Great question.  A380 and B-747 had nearly equal number of orders for the first 10 years.  Thereafter, for the B-747, orders jumped dramatically.  Will the A380 follow the pattern?  Probably not.  First, Boeing kept improving the 747 following its launch, delivering it in several models.  (In fact, its all-time best-seller, the 747-400, was still in the future.)  The A380 design has been stagnant.  Second, the B-747 had a huge advantage over its nearest competitors at the time (DC-10 and L-1011) in range - nearly 10,000 km for the initial version, v. 6000 for Douglas and 5000 for Lockheed (albeit numbers increased considerably for all over time.)  Simply put, the B-747 could fly routes that no-one else could.  While the A380 has superb range, it is not unmatched.  Studies have shown that number of seats per plane is largely unchanged over the past decade (or more), so capacity by itself doesn't sell planes.  Finally, Boeing designed the 747 from the beginning to be usable as a front-loading freighter.  Airbus has never mastered the concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer - I have never owned or operated an airline.  Just interested in market dynamics.&lt;/p&gt;&#xA;" OwnerUserId="11579" LastEditorUserId="11579" LastEditDate="2015-10-05T01:23:27.817" LastActivityDate="2015-10-05T01:23:27.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21610" PostTypeId="2" ParentId="21607" CreationDate="2015-10-05T01:50:30.067" Score="3" Body="&lt;p&gt;This answer assumes that the question is in the context of the FAA's jurisdiction.&lt;/p&gt;&#xA;&lt;p&gt;The red, green and white lights are &lt;strong&gt;position lights&lt;/strong&gt;. They are required from sunset to sunrise by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1209&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.203&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) During the period from sunset to sunrise (or, in Alaska, during the period a prominent unlighted object cannot be seen from a distance of 3 statute miles or the sun is more than 6 degrees below the horizon)—&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(1) Operate an aircraft unless it has lighted position lights;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A solid red or solid white light on the underbelly doesn't correspond to a configuration that I am familiar with and doesn't meet the legal requirements.&lt;/p&gt;&#xA;&lt;p&gt;I have, however, seen some older varieties of rotating beacons that if broken may become a solid red light mounted on the underbelly. Some older models actually have a motor that actuates rotation. If one had a failed motor it could appear as a solid red light.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/rMI6Tp2.jpg&quot; alt=&quot;rotating beacon&quot; /&gt;&lt;/p&gt;&#xA;&lt;p&gt;The strobes are &lt;strong&gt;anticollision lights&lt;/strong&gt;. The answer is also in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1209&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.203&lt;/a&gt; . If anticollision lights are installed, they must be used unless the pilot turns them off in the interest of safety. The most common reason for this is if the aircraft is flying in the clouds and the diffuse strobing lights are a distraction or cause of disorientation such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Flicker_vertigo&quot; rel=&quot;nofollow noreferrer&quot;&gt;flicker vertigo&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) During the period from sunset to sunrise (or, in Alaska, during the period a prominent unlighted object cannot be seen from a distance of 3 statute miles or the sun is more than 6 degrees below the horizon)—&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(b) Operate an aircraft that is equipped with an anticollision light system, unless it has lighted anticollision lights. However, the anticollision lights need not be lighted when the pilot-in-command determines that, because of operating conditions, it would be in the interest of safety to turn the lights off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1205&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.205&lt;/a&gt; is also relevant. Parts of it deal with the FAA requirements for both position and anticollision light systems. It states that aircraft may not be operated without position lights. It also states that aircraft may not be operated without anticollision lights installed with some exceptions.&lt;/p&gt;&#xA;&lt;p&gt;There are some provisions by which a flight may be conducted legally with broken lights so that it may be repaired. One such provision is also found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1205&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.205&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(11) For small civil airplanes certificated after March 11, 1996, in accordance with part 23 of this chapter, an approved aviation red or aviation white anticollision light system. In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If you're really interested, and I mean &lt;strong&gt;really really&lt;/strong&gt; interested, the FAA released &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-74.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 20-74&lt;/a&gt; which contains a lot of technical data on exactly how these lights are to be built in terms of intensity, color and position. Delving into this document should be reserved for the truly bored and those who manufacture aircraft lighting.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-05T02:00:18.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21612" PostTypeId="1" AcceptedAnswerId="39469" CreationDate="2015-10-05T02:10:08.217" Score="13" ViewCount="6614" Body="&lt;p&gt;What are the dimensions of the protected space provided by a holding pattern? Where and how does the FAA define this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While &lt;a href=&quot;https://aviation.stackexchange.com/questions/21568/how-to-correct-for-crosswind-in-vor-holding-pattern-without-wind-information&quot;&gt;this question&lt;/a&gt; may contain the answer, this question concisely asked something that is a valid aviation question and it warrants its own answer.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2020-09-24T02:02:30.757" Title="What are the dimensions of the protected space provided by a holding pattern?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21613" PostTypeId="2" ParentId="21602" CreationDate="2015-10-05T02:27:57.897" Score="4" Body="&lt;p&gt;The issue with many things in flight safety is that the status quo is well understood. Changing something introduces a whole body of unknowns, and considerable circumspection will be applied by the people charged with ensuring safety. This is why piston engines in many light planes are almost identical to those used half a century ago - they're known to work - and why there is considerable inertia when it comes to updating your software tools.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, the only way things are likely to move is when somebody builds a case for updating the tools that shows sufficient commercial benefit to overcome the additional cost of certifying the final product. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It won't be enough to simply argue that a new compiler has this or that set of new features. You'll need to demonstrate that using the new compiler will allow you to provide a set of new features that you can't provide with the old one, and that this will lead to a tangible increase in sales.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck!&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-05T02:27:57.897" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21614" PostTypeId="1" AcceptedAnswerId="21617" CreationDate="2015-10-05T02:34:58.723" Score="9" ViewCount="5034" Body="&lt;p&gt;I was listening to some RealATC this evening and came to &lt;a href=&quot;https://youtu.be/biDnVJ6EqA8&quot;&gt;this one&lt;/a&gt; about an accident at LaGuardia airport. This question is not about the accident in any way, but I am using this video because it has an example of what I mean and has a labelled diagram as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the clip advances, it becomes clear that at that time, planes were landing via ILS Runway 13. However, planes were being directed to takeoff from Runway 4.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under what circumstances might a major commercial airport have planes landing and departing via crossing runways, instead of on the same, or at least parallel?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="1696" LastEditDate="2018-04-10T02:51:01.863" LastActivityDate="2018-04-10T02:51:01.863" Title="Why would an airport use crossing runways for takeoff and landings?" Tags="&lt;landing&gt;&lt;airport&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21615" PostTypeId="2" ParentId="21614" CreationDate="2015-10-05T02:46:58.120" Score="9" Body="&lt;p&gt;Any time the winds and traffic permit an airport may chose to use intersecting runways. You can read some interesting info on it &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.652_Converging_Runway_Operations.pdf&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/publications/media/Runway_Safety_Best_Practices_Brochure.pdf&quot;&gt;here&lt;/a&gt;. In some cases when both runways are in use they may have the aircraft execute &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Land-and-Hold-Short-Operations-LAHSO&quot;&gt;Land And Hold Short&lt;/a&gt; procedures. The pilot has the final say in a LAHSO situation and you can call no joy if you think you cant complete the maneuver as requested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports may only have 2 runways set up in an intersecting layout and may not have the luxury of parallel runways. Depending on terminal layout at commercial airports using both runways may aid in traffic flow on the ground as well as getting planes in the air.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winds permitting generally have to do with the maximum cross wind component of a given airplane. Although generally speaking you will see this done in calm wind situations. The other cause I have seen for this is instrumentation, some airports may have intersecting runways that are not equipped the same or of the same length. As lets say the favorable runway is is 5000ft visual approach only strip and you need 6000ft to land. Luckily the airport has another intersecting runway that is a 7000ft strip (and has an ILS approach not that you need it (its nice out)). They may have you come into the other runway while they sequence small visual traffic on to the short strip (possibly having them land short if need be).   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-05T02:58:44.733" LastActivityDate="2015-10-05T02:58:44.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21617" PostTypeId="2" ParentId="21614" CreationDate="2015-10-05T03:09:23.190" Score="8" Body="&lt;p&gt;&lt;strong&gt;They need the throughput.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Got to use what you have. They utilize their crossing runways to the full under any conditions that allow it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Major commercial airports try to have as many parallel runways as possible, as crossing runways are a hassle. (See DFW, ATL, LAX, many other examples of new or remodelled major airports using almost exclusively parallel runways). But sometimes (for any number of reasons, a main one at LGA being space) parallel runways haven't been built, so they can't be used.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-10-05T03:09:23.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21618" PostTypeId="1" CreationDate="2015-10-05T04:49:39.970" Score="1" ViewCount="224" Body="&lt;p&gt;I have seen the shape of the A320s engine and for example the B737 engine, its different, I want to know why its different? is it just for designing? &lt;/p&gt;&#xA;" OwnerUserId="11581" LastActivityDate="2015-10-05T04:49:39.970" Title="Why jet engines can differ in shape?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-performance&gt;&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2015-10-05T06:12:50.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="21619" PostTypeId="1" AcceptedAnswerId="21621" CreationDate="2015-10-05T06:58:02.503" Score="76" ViewCount="29711" Body="&lt;p&gt;In the answer to &lt;a href=&quot;https://aviation.stackexchange.com/q/21594/8730&quot;&gt;this question&lt;/a&gt; it is noted that the B-52 takes off without &lt;a href=&quot;https://en.wikipedia.org/wiki/Rotation_%28aeronautics%29&quot; rel=&quot;noreferrer&quot;&gt;rotating&lt;/a&gt; and climbs out in a nose-down attitude. Why was it designed this way?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="15311" LastEditDate="2017-12-08T08:36:09.773" LastActivityDate="2020-06-08T01:53:33.043" Title="Why does the B-52 take off without rotating?" Tags="&lt;takeoff&gt;&lt;angle-of-attack&gt;&lt;attitude&gt;&lt;b-52&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21620" PostTypeId="1" AcceptedAnswerId="22703" CreationDate="2015-10-05T07:03:49.827" Score="12" ViewCount="590" Body="&lt;p&gt;This weekend I was on a Airbus A319, and I noticed that the flaps have small extensions at the location of the shockbodies (indicated in the picture with the red circles)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;I was wondering what the reason is for these extensions?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;My guess is that it could be to compensate for the lower local lift generation caused by the presence of the shock bodies, but I'm not sure. I'm also interested in knowing why they have different sizes at different locations.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uM1OS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uM1OS.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-05T16:46:07.663" Title="What's the reason for the local flap extensions at the shockbody locations?" Tags="&lt;flaps&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21621" PostTypeId="2" ParentId="21619" CreationDate="2015-10-05T07:34:37.860" Score="79" Body="&lt;p&gt;The reason was to give the bombs the place close to the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing sweep (for high cruise Mach numbers) in combination with a high aspect ratio of the wing (for low induced drag) made it impossible to place the landing gear in the wing, so it had to be integrated into the fuselage. The main landing gear normally needs to be &lt;a href=&quot;https://aviation.stackexchange.com/questions/16447/landing-gear-position-on-caravan/16455?s=1%7C0.3305#16455&quot;&gt;close to the center of gravity&lt;/a&gt; (slightly behind for a tricycle gear, slightly ahead for a taildragger), but this space was needed for the massive bomb bay. Since the bombs will be dropped somewhere along a bombing mission, dropping them should not upset the balance of the aircraft, so no compromise was possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r1hD4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r1hD4.jpg&quot; alt=&quot;B-52 cutaway drawing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-52 cutaway drawing showing the two bomb bays in the center of the fuselage (picture &lt;a href=&quot;http://www.combatreform.org/B52cutaway.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This problem existed already during the development of the 6-engined &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-47_Stratojet&quot; rel=&quot;noreferrer&quot;&gt;B-47&lt;/a&gt; a few years before. In both designs, two pairs of landing gears were chosen, one pair ahead and one pair aft of the bomb bay, and the aircraft lost its ability to rotate for takeoff. Due to the powerful fowler flaps the attitude in cruise and at slow speed could be made identical. The downside is more drag during the take-off run, since the wing produces more lift, but this could be tolerated in a strategic bomber with air refueling capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zwfKo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zwfKo.jpg&quot; alt=&quot;B-47 on approach with drag chute deployed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-47 on approach with gear down and drag chute deployed (picture &lt;a href=&quot;http://www.wattflyer.com/forums/attachment.php?attachmentid=132255&amp;amp;stc=1&amp;amp;d=1279601028&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the outriggers between the inner pair of engines - those were needed to keep the aircraft level on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ogFn2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ogFn2.jpg&quot; alt=&quot;B-52 in flight with gear down&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B-52 in flight with gear down (picture &lt;a href=&quot;http://www.air-and-space.com/edw98/b52ha%20l.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Here the forward and aft gear of the B-47 have been replaced by pairs of gears to distribute the load over eight wheels and the outriggers are positioned outside of the outer engine pair, but the general gear configuration is fairly similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Russian design bureau Myasishchyev found a different solution for their &lt;a href=&quot;https://en.wikipedia.org/wiki/Myasishchev_M-50&quot; rel=&quot;noreferrer&quot;&gt;M-50 supersonic bomber&lt;/a&gt; in the mid-50s. They also had to put the bomb bay into the center fuselage and the main gear had to be placed so far aft that the M-50 could not be rotated the usual way with the elevator. To solve the problem, the engineers devised what they called the &quot;galloping bicycle&quot;. When the aircraft reached 300 km/h, the forward gear rapidly extended to rotate it to 10°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a73yI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a73yI.jpg&quot; alt=&quot;Myasishchyev M-50 with extended front gear strut&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Myasishchyev M-50 with extended front gear strut (picture &lt;a href=&quot;http://www.testpilot.ru/russia/myasishchev/m/50/images/m50-12.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The two open doors under the cockpit were for the pilot and navigator: Their downward-ejecting seats would be lowered on cables for the crew to be strapped in at ground level, then winching themselves into place.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-12-08T05:29:43.860" LastActivityDate="2017-12-08T05:29:43.860" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21622" PostTypeId="1" AcceptedAnswerId="21629" CreationDate="2015-10-05T10:14:56.980" Score="2" ViewCount="4421" Body="&lt;p&gt;I've gone through the following questions on Stack Exchange and other few questions too:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3902/why-is-managing-cg-centre-of-gravity-important-for-aircraft&quot;&gt;Why is managing CG (centre of gravity) important?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15180/how-are-the-limits-of-the-center-of-gravity-chart-established&quot;&gt;How are the limits of the center of gravity chart established?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I still do have 2 questions in mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How do they adjust the fuel quantity/weight based on the passengers' weight on the plane? (was there any situation where few fat guys have been asked to move to front or back because I never saw any airliner weighing their passengers before boarding)&lt;/li&gt;&#xA;&lt;li&gt;As the fuel starts burning, the pilot will fill/empty/exchange it from wing to wing or other storage location to balance CG, Will this cause imbalance (moving out of defined tolerances) in CG based on the passengers' weight?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="28025" LastEditDate="2018-01-05T02:45:40.500" LastActivityDate="2018-01-05T02:45:40.500" Title="How Centre of Gravity (CG) is adjusted?" Tags="&lt;passenger&gt;&lt;fuel&gt;&lt;cg&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21623" PostTypeId="1" AcceptedAnswerId="21631" CreationDate="2015-10-05T11:07:26.357" Score="0" ViewCount="139" Body="&lt;p&gt;As we know we set the flight path etc in FMC but can it be pre programmed to do high speed maneuvering and shoot the ammo as per the preset conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It could be kind of self moving UAV with the pre stated path, waypoints, targets to hit and the return path along with the type of ammo to hit depending upon the kind of target.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="62" LastEditDate="2016-07-05T15:01:23.530" LastActivityDate="2016-07-05T15:01:23.530" Title="Can FMC be programmed to do fast maneuvering in fighter jets?" Tags="&lt;military&gt;&lt;autopilot&gt;&lt;maneuver&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21624" PostTypeId="1" AcceptedAnswerId="21625" CreationDate="2015-10-05T11:20:57.330" Score="17" ViewCount="5344" Body="&lt;p&gt;Normally, it seems all the stealth designs dont use podded engines like others. Is this just to avoid the radar cross-section?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="-1" LastEditDate="2015-10-05T13:34:40.603" LastActivityDate="2015-12-27T15:11:05.873" Title="Why don't stealth aircraft designs use podded engines?" Tags="&lt;stealth&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21625" PostTypeId="2" ParentId="21624" CreationDate="2015-10-05T11:28:35.977" Score="26" Body="&lt;p&gt;Yes. From the PoV of stealth aircraft, the podded engine has significant disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engine pod has a high Radar Cross Section; In fact, stealth aircraft bury the engine inside their fuselages to minimize radar cross section. For example, the B2 Spirit engines were located inside the fuselage, as shown in the schematic below.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GwyhR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GwyhR.jpg&quot; alt=&quot;B-2 Engine schematic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The exposed compressor blades in the podded engine reflects radar waves, which is not good. For example, in Boeing X-32, the location of the engine meant that the compressor blades will be exposed to the Radar and baffles were (proposed to be) added to reduce the Radar cross section. On the other hand, it can be seen that it is practically impossible to see the F-22 compressor blades from any angle of the inlet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mYA1W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mYA1W.jpg&quot; alt=&quot;F-22 intake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: f-16.net&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of podded engine, it is difficult to shield the exhaust thermal signature. Compare the infrared signature of the typical airliner in the following picture with that of the B-2 Spirit in the next picture.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tHlUS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tHlUS.jpg&quot; alt=&quot;Civil aircraft Infrared&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: laserfocusworld.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z0wT8.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z0wT8.gif&quot; alt=&quot;B2 IRST&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: bestfighter4canada.blogspot.in&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, contemporary combat aircraft don't use podded engines at all (with the exception of the A-10, which is a ground attack aircraft). &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-05T11:52:44.660" LastActivityDate="2015-10-05T11:52:44.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21626" PostTypeId="1" AcceptedAnswerId="21627" CreationDate="2015-10-05T11:52:47.823" Score="4" ViewCount="3337" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dvK54.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dvK54.jpg&quot; alt=&quot;Wing Vortex Prop&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: www.airliners.net)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These circles I believe are the wing tip vortex formed by the propeller tips or is it just due to the rotation of the propeller. How does this occur?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2015-10-05T14:21:52.820" LastActivityDate="2019-02-25T20:22:50.277" Title="What are these circles around the propeller?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21627" PostTypeId="2" ParentId="21626" CreationDate="2015-10-05T12:02:08.937" Score="10" Body="&lt;p&gt;They are tip vortices formed by the propeller, just like the wing tip vortices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propeller produces thrust, just like the normal wing produces lift. As any wing of &lt;em&gt;finite length&lt;/em&gt; produces vortices, the propeller also produces them and that is what you see in the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not only limited to propellers. The helicopter rotors also do the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QEQmO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QEQmO.jpg&quot; alt=&quot;Propeller vortices&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-05T12:02:08.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21628" PostTypeId="2" ParentId="21622" CreationDate="2015-10-05T12:11:46.177" Score="1" Body="&lt;p&gt;In the majority of airplanes fuel is stored in the wings and tanks which are positioned at or near the center of gravity at empty. This limits the forward-back moment arm of the fuel so as fuel is used up the center of gravity does not shift forward or back that much. Balancing fuel weight is therefore more of a question of lateral CG, a pilot (or automatic onboard system) can pump fuel or switch tanks to balance fuel load. The seating configuration of passengers does not have much impact on lateral CG as their moment arm is very small. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In light aircraft passenger weight and position is a big concern, however passengers are actually one of the smallest weight components on a commercial airliner compared to the plane itself, fuel and cargo. You won't see overweight people being asked to move to balance a commercial aircraft. Seating systems deal with numbers and are designed to spread the load evenly across CG. Even if all the passengers of a half-empty commercial jet sat at the back there would still be enough trimming power to keep the airplane in balance. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-10-05T12:11:46.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21629" PostTypeId="2" ParentId="21622" CreationDate="2015-10-05T12:20:34.053" Score="4" Body="&lt;p&gt;The main issue is what is referred to as the Weight and Balance of the aircraft. When an aircraft is in flight, its weight and balance needs to be within a controllable range in order to ensure the plane can both recover from a stall condition and rotate on takeoff. This is visualized by the weight and balance &quot;envelope:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qEjxv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qEjxv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, there are limits where the aircraft is not fit for flight. We must stay inside the drawn lines in the center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your detailed questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;On airlines, a &quot;Magic&quot; number was used to approximate all weight for passengers and baggage. This caused at least one  notable accident: &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Midwest_Flight_5481&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Midwest Flight 5481&lt;/a&gt;. As a result of this accident, policies were changed to get more accurate baggage and passenger weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In GA flight, it is not uncommon for pilots to ask for passenger weights. Usually, as a rule, we add a bit to that in case people are embarrassed (10%). It is very common for pilots to assign seating on smaller aircraft with heavier people sitting in a location where the distance to the datum is smallest (near the front).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Weight and balance can be moved out of limits by fuel burn. In fact, a few questions on the private pilot written exam deal with this exact scenario. Most planes have tanks near the CG, so they don't experience problems with fuel burn. In planes with an aft belly tank, the CG can move forward significantly and out of limits. This would cause the aircraft to be unable to pitch up as desired. Swept wing jets that use horizontal stabilizer tanks in the tail of the aircraft have computers and pumps to move the fuel as desired to keep their CG in the desired place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots of smaller/less traditional airplanes need to be conscious of this, and plan accordingly. Especially those with a-typical fuel tank positions. Pilots of larger commercial style aircraft are less concerned with the exact position of 1 or 2 large people or heavier bags because their aircraft has a much bigger capacity and less &quot;sensitive&quot; envelope. They still are affected by the physics, though, just like everyone else.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2015-10-05T12:26:46.563" LastActivityDate="2015-10-05T12:26:46.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21630" PostTypeId="2" ParentId="21619" CreationDate="2015-10-05T13:16:43.983" Score="54" Body="&lt;p&gt;Adding to the excellent Peter's answer who explained why for this particular model the wheels are placed far behind the centre of gravity (CG), I would like to clarify why this makes impossible to rotate at take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A standard aircraft takes off right after the rotation, increasing the angle of attack and the lift. Before and while performing the rotation the lift produced by the wings is not enough to raise the position of the CG. Still, with the wheels placed right behind the CG, a small raise of the CG is required during the rotation. This is accomplished with the down force produced by the elevator and its big leverage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6X31n.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6X31n.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the wheels are moved backwards, then such lever becomes much less advantageous: the force produced by the tail on the CG is weaker, because the fulcrum is closer to it and farther from the CG. The maximum elevator down force and the structural strength can then make the rotation impossible.&lt;/p&gt;&#xA;" OwnerUserId="2345" LastEditorUserId="2345" LastEditDate="2015-10-05T14:28:29.383" LastActivityDate="2015-10-05T14:28:29.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21631" PostTypeId="2" ParentId="21623" CreationDate="2015-10-05T13:19:48.963" Score="1" Body="&lt;p&gt;Pre-programmed high speed maneuvering is already being done in the case of target drones derived from fighter aircraft like the QF-16 (which is derived from F-16). According to &lt;a href=&quot;http://www.aviationtoday.com/av/issue/feature/QF16-Unmanned-Viper-Takes-Flight_81908.html&quot; rel=&quot;nofollow&quot;&gt;multiple reports&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The QF-16 ... is capable of pre-programmed maneuvers such as high-G turns, barrel rolls, split-S, etc.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While some research has been carried out on fully autonomous weapons systems, at present there is always a human being in the loop (at-least) for pressing the 'kill switch'. A few of the problems in a fully autonomous system operating in enemy airspace are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Operating the UAV in hostile area and responding to threats. Though the QF-16 drones can fire chaff and flares to escape from incoming missiles, drones that can operate in hostile environment are still in their infancy. This requires significant improvements in ability of the UAVs to detect, differentiate and prioritize the threats and respond to them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The UAVs should have the ability to search/track, acquire and engage the target while not ignoring friendlies or neutrals. Though some tests have been carried involving automated target tracking and some missile do have the ability to discriminate between the target and surrounding buildings (based on prior information),the technology is still some way off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are significant political, legal and ethical issues in using automated killing machines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some missiles like the &lt;a href=&quot;http://www.ausairpower.net/Tomahawk-Subtypes.html&quot; rel=&quot;nofollow&quot;&gt;Tomahawk&lt;/a&gt; has the ability to navigate along a predetermined path and hit targets, though they cannot do high speed maneuvers (or return, obviously).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-05T13:19:48.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21633" PostTypeId="1" AcceptedAnswerId="21655" CreationDate="2015-10-05T14:31:15.877" Score="13" ViewCount="13196" Body="&lt;p&gt;Is it possible for a passenger to determine the aircraft's altitude and or speed or location using any mobile apps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all airlines have displays with constant info about this. I had tried using Google maps, but it did not work, maybe because there was no internet/wifi on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any simple method?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="7532" LastEditDate="2015-11-17T04:19:36.413" LastActivityDate="2015-11-17T16:58:21.177" Title="How to determine aircraft altitude and speed, as a passenger?" Tags="&lt;airspeed&gt;&lt;altitude&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21634" PostTypeId="1" CreationDate="2015-10-05T16:18:05.240" Score="1" ViewCount="1324" Body="&lt;p&gt;When does a person &lt;em&gt;first&lt;/em&gt; hear a plane, flying faster than the speed of sound, as it flies directly overhead? Yes, I know there is a sonic boom and I also know the plane will produce sound as it flies away from that person. But what about the sound that the plane produces as it's flying &lt;em&gt;towards&lt;/em&gt; the person? Will the sound be different from the sound heard after the plane has passed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My dad and I have discussed this and looked at a partial explanation on Youtube, but there wasn't anything - as far as we could find - on the sound produced when the plane was coming &lt;em&gt;towards&lt;/em&gt; a person.&lt;/p&gt;&#xA;" OwnerUserId="11587" LastEditorUserId="62" LastEditDate="2015-10-05T16:54:42.973" LastActivityDate="2015-10-05T16:54:42.973" Title="When will I hear the sonic boom from a plane flying towards me?" Tags="&lt;supersonic&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-10-05T18:36:54.607" ContentLicense="CC BY-SA 3.0" />
  <row Id="21635" PostTypeId="2" ParentId="21599" CreationDate="2015-10-05T16:26:50.707" Score="3" Body="&lt;p&gt;That data may not be directly available but you may be able to piece it together. &lt;a href=&quot;http://blog.aopa.org/opinionleaders/2014/03/13/do-tbos-make-sense/&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; has some of the only numbers I have ever seen (although they may not be 100% accurate). &lt;a href=&quot;http://4vfr.com/?goto=view_article&amp;amp;section=articles&amp;amp;article_key=296&quot; rel=&quot;nofollow&quot;&gt;Here are some random facts on engine failures&lt;/a&gt; that have no sources quoted so take it for what you will. There is some interesting info on why the engines fail &lt;a href=&quot;http://www.avweb.com/news/maint/182849-1.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://blog.aopa.org/opinionleaders/2014/04/09/how-do-piston-aircraft-engines-fail/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. Your best bet for piecing the information together is to look over the actual &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Pages/aviation.aspx&quot; rel=&quot;nofollow&quot;&gt;NTSB reports&lt;/a&gt;. For this you are going to want to pull them and have a way to comprehensively sort and filter them (which is really a computer science question not an aviation question). Since the plane is listed you should be able to extrapolate the engine from the report that way. You can also find some &lt;a href=&quot;http://www.supercub.org/forum/showthread.php?46407-Engine-failure-how-common-are-they&quot; rel=&quot;nofollow&quot;&gt;discussion on the matter here&lt;/a&gt; as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue with building a chart like this is there are many many variables and generally speaking (at least from the NTSB reports I have read) engine failures are often linked to improper maintenance or improper use more than they are related to an engine component simply breaking. In many cases it only takes one failure for an AD to be issued and the problem to be solved. Engines like the more common Lycomings and Continentals you find in GA planes today have been around for some time and proven to be reliable and simple. Mechanics know them through and through and there are years of validation to support TBO numbers and things like that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.vansairforce.com/community/showthread.php?t=28452&quot; rel=&quot;nofollow&quot;&gt;This thread&lt;/a&gt; seems to provide real numbers pulled from NTSB reports (at least thats what the guy claims). Its an interesting read if the numbers are correct. The fact remains that engine failures are rare (in the grand scheme of things) but do occur and should always be prepared for. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-05T16:26:50.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21636" PostTypeId="2" ParentId="21634" CreationDate="2015-10-05T16:41:14.257" Score="0" Body="&lt;p&gt;In case a supersonic aircraft (flying faster than the speed of sound) flies directly over a person, that person (the observer) will not hear anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The (supersonic) aircraft produces sound throughout its flight (i.e. while flying towards as well as away from you). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sonic boom you hear is the sound produced by the aircraft when it was coming towards you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For how this works, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/14783/what-is-the-simplest-way-to-explain-a-sonic-boom-that-is-still-technically-corre&quot;&gt;this question&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sonic_boom&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia page&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-05T16:41:14.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21637" PostTypeId="2" ParentId="21599" CreationDate="2015-10-05T17:55:27.643" Score="4" Body="&lt;h2&gt;Short (pilot's) Answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&quot;Reliable enough for you to fly behind one, flaky enough that you should always expect them to fail at the least convenient moment.&quot;&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Short (Mechanic's) Answer&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&quot;More reliable than the pilot!&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h3&gt;Longer Answer&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;You can't really know the &lt;em&gt;failure rate&lt;/em&gt;, but you can know the &lt;em&gt;accident rate attributable to engine failures&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/aviation-special-studies/AAS72-10.pdf&quot; rel=&quot;nofollow&quot;&gt;The NTSB looked at this back in 1972&lt;/a&gt; and Embry-Riddle still has the report available. It's very interesting reading, and goes into great detail on the specific &lt;em&gt;causes&lt;/em&gt; of engine failure.&lt;br&gt;&#xA;Totaling up everything they classified as &quot;engine failure&quot; gave a failure-related-accident rate of just under 18 per 100,000 hours (i.e. &quot;Assuming proper maintenance you could theoretically fly 5,000 hours in piston GA aircraft before you'd have an engine-failure-related accident.&quot;)&lt;br&gt;&#xA;There may be a more current NTSB study on this, I honestly didn't look too hard as I expect the numbers to be broadly similar today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Accident-Analysis/Joseph-T-Nall-Report&quot; rel=&quot;nofollow&quot;&gt;24th Nall report&lt;/a&gt; shows 61 &quot;powerplant&quot; accidents (all engine types, and including the propeller and associated systems) - the number is not broken down per 100,000 hours but doing a little extrapolation from their other figures it works out to about 0.4 accidents per 100,000 flight hours (or &quot;Assuming proper maintenance you could theoretically fly 200,000 hours in piston GA aircraft before you'd have an engine-failure-related accident.&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanic's answer of &quot;More reliable than the pilot!&quot; comes into play when you look at the pilot-related accident numbers: In the 1972 NTSB report I cited engine failures made up 13% of the total accident figure. In the 24th Nall report &lt;em&gt;all mechanical accidents&lt;/em&gt; were 14% of non-commercial fixed-wing accidents (17% of commercial accidents) - that includes a number of other systems (e.g. landing gear) which are unrelated to the engine.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-05T17:55:27.643" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21638" PostTypeId="2" ParentId="21396" CreationDate="2015-10-05T18:13:07.923" Score="-3" Body="&lt;p&gt;Google '747 5th engine'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The early days of the 747 program did not have spare parts readily available at remote locations.  The 747 was originally designed to externally carry a 5th engine under the left wing in the event one 747 had to ferry an engine to a grounded 747 somewhere remote.&lt;/p&gt;&#xA;" OwnerUserId="11593" LastActivityDate="2015-10-05T18:13:07.923" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21640" PostTypeId="2" ParentId="21624" CreationDate="2015-10-05T20:32:25.837" Score="5" Body="&lt;p&gt;In addition to aeroalias's very detailed answer, I think a good point to start with this question is: &quot;Why would any aircraft not use podded engines?&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few advantages of having an engine in a separate pod, commonly it comes down  to a simple lack of room in your fuselage. Either your thrust requirements would require too many or too large of engines to fit streamlined in a body that fulfills your other specifications. So, we see these on things with massive thrust requirements, which are almost exclusively cargo/transport or bomber aircraft. There are a few other bonuses too, like accessibility for maintenance or removing the sound and heat from the body of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, they also present massive, super-hot, and exposed targets. So for any combat aircraft that has the option, they will be onboard. The only combat aircraft I know of with podded engines, the A-10, has to push a very heavy airframe around with high mission loads. The main body is kept remarkably thin, thanks to the lack of internal weapon bays, so it makes more sense to mount these two large engines in pods then to grossly swell the body to fit them. It also gives more freedom in the placement and alignment of these engines, which are a bit particular for the A-10 given its unique lift and weight distribution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are additional reasons why you would avoid mounting these on a stealth aircraft, but for airframes like the F-22 or F-35, it wouldn't have made sense anyway. Large stealth aircraft like the SR-71 and B-2 are sleek enough that the requisite engines can fit rather comfortably within the design of the wing as well, so podding them would only hamper the design.&lt;/p&gt;&#xA;" OwnerUserId="11595" LastActivityDate="2015-10-05T20:32:25.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21641" PostTypeId="1" CreationDate="2015-10-05T20:41:16.877" Score="4" ViewCount="675" Body="&lt;p&gt;I'm working on a budget for operating an aircraft and trying to better understand the hourly operating costs.  What factors should be included that are often forgotten?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although this is partially discussed &lt;a href=&quot;https://aviation.stackexchange.com/questions/77/what-are-the-typical-facets-of-ownership-costs-for-a-single-engine-aircraft&quot;&gt;here&lt;/a&gt; I'm interested in distinguishing between general cost of ownership (hangar, insurance costs, etc.) with items specific to hourly costs. And I'm not looking for actual numbers - just the categories to consider.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously this list will depend upon the type of aircraft, but to keep the question somewhat general, I'm interested in a light single-engined piston aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far my categories include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cost of fuel per hour&lt;/li&gt;&#xA;&lt;li&gt;Engine reserve per hour&lt;/li&gt;&#xA;&lt;li&gt;Prop reserve per hour&lt;/li&gt;&#xA;&lt;li&gt;Oil cost per hour&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-05T21:35:51.133" Title="What factors should be included when calculating hourly aircraft operating cost?" Tags="&lt;general-aviation&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ClosedDate="2015-10-06T02:55:49.247" ContentLicense="CC BY-SA 3.0" />
  <row Id="21642" PostTypeId="2" ParentId="21641" CreationDate="2015-10-05T20:54:36.893" Score="2" Body="&lt;p&gt;Unless you have a private airstrip and have no intention of insuring the craft you need to include the fixed costs as well. Generally you can do this yearly, then divide by the number of expected hours a year. Some fixed costs are &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Storage (hanger or tie down)&lt;/li&gt;&#xA;&lt;li&gt;Insurance (highly variable)&lt;/li&gt;&#xA;&lt;li&gt;Annual (this will vary depending on whats broken but there is generally a minimum situation to expect assuming the mechanic finds nothing wrong.&lt;/li&gt;&#xA;&lt;li&gt;Anything that has less than a 50 hour life time, if you are in this for ownership or renting you are going to fly more than 50 hours a year (I would hope) so you should budget in things like spark plugs, break pads and other high wear parts that get replaced often) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other reserves may be &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Repaint Reserve, this will vary depending on storage and use &lt;/li&gt;&#xA;&lt;li&gt;Landing Gear Reserve this includes but is not limited to, breaks, tires, shocks, rotors, etc. Budget more if its a complex plane, less if its a Mooney... &lt;/li&gt;&#xA;&lt;li&gt;Fluid Reserve (not oil) you may also have hydraulic fluid and break fluid.  &lt;/li&gt;&#xA;&lt;li&gt;&quot;Toys&quot; this is money you may chose to add on to your reserve so that you can (down the line) upgrade aging components that may not be broken. For example adding a 430 in place of a radio pair or moving to a full or partial glass cockpit. &lt;/li&gt;&#xA;&lt;li&gt;Interior, if you are renting this plane and expect it to see heavy use you may want to set some cash aside for the interior. Don't underestimate the difference a warn seat will make vs a fresh seat.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Emergency Fund&lt;/strong&gt;: This is not a reserve to add to as much as it is cash on hand. If you are renting this plane or even relying on it for heavy personal use you may want to have a budget for emergencies. Especially if you are renting and a down plane means lost rentals. What are you going to do if you need a new fuel tank, or you have a bird strike, or something hits the windshield and cracks it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Odds and Ends Budget&lt;/strong&gt;: Nuts and bolts, interior finish screws, that dinky little plastic knob, repainting your yoke, a pitot tube cover (for the 10th time because you lost all the other ones...) &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-05T20:54:36.893" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21644" PostTypeId="2" ParentId="21633" CreationDate="2015-10-05T22:20:25.450" Score="10" Body="&lt;p&gt;There's a great app for that info called &lt;a href=&quot;https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&amp;amp;feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5lY2xpcHNpbS5ncHNzdGF0dXMyIl0.&quot;&gt;GPS Status &amp;amp; Toolbox&lt;/a&gt; It gives you speed, altitude, longitude and latitude from your GPS. It will also give you pitch, roll, heading and acceleration data. None of this needs a data connection, just a view of GPS satellites. Never tried to get GPS from inside a plane, though. Not sure how well that works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to see your location on a map, if the plane doesn't have wifi, you'll have to download an offline map app. There's several of them available. The Google maps offline feature wouldn't work, really, because it only lets you download a certain size of tile. It took four such tiles to include the entire metro area of my home city (KC). It's pretty data heavy. Rural areas with less data can get a somewhat bigger tile, but if you're flying very far it would take forever, a lot of effort and memory space to download enough tiles to cover the whole trip offline.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-05T22:20:25.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21645" PostTypeId="1" CreationDate="2015-10-05T23:36:19.170" Score="8" ViewCount="576" Body="&lt;p&gt;I once found a video of a single engine, piston and propeller, high wing plane that had been built, or modified by a US college/university. They added a 200 HP turbine engine behind the baggage compartment up high in the fuselage and it drove a turbine compressor. Pretty much like a airliner starter turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high pressure air from the compressor went out to the flaps pivot axle and then into the flaps inner space. The flaps pivoted &lt;em&gt;at the trailing edge&lt;/em&gt;, and so folded out by hinging down and back. Then, the edge that had been buried in the wing's underside &lt;em&gt;forward&lt;/em&gt; of the pivot point was now the trailing edge. This trailing edge was a rounded tube of about 1.4 inches to 2.5 inches in OD. It had a jet flap blowing along the top surface and caused entrained air fom the top of the wing to go down 90 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It cruised around 150 to 200 mph, but landed around 30 MPH. Pretty incredible. I can't for the life of me find it again in Google or Youtube. Does anybody know about this project? I'd love to save that video down to my hard drive. Even better, I'd love to go see the plane.&lt;/p&gt;&#xA;" OwnerUserId="11597" LastEditorUserId="19" LastEditDate="2016-11-11T13:19:30.113" LastActivityDate="2016-11-11T13:19:30.113" Title="Where can I find that video of a college built blown wing aircraft?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;usa&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21646" PostTypeId="1" CreationDate="2015-10-05T23:57:23.883" Score="16" ViewCount="2030" Body="&lt;p&gt;I was reading some literature on stalls and spins (which are almost always preceded by a stall) of aircraft when a thought hit me. Why can't a model aircraft (1/4 scale of manned aircraft) be used to inexpensively explore the stall and spin behavior of manned aircraft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(One disclaimer for this, I know this can't be done at ALL speed ranges or all scales. Airliners are too big to make inexpensive 1/4 scale R/C aircraft, and aircraft that cruise at transsonic speeds will not benefit from this since the effects seen there only happen at that particular reynolds and mach number combination) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I was thinking more for aircraft that spend a lot of time at fairly low speed (below Mach 0.3) such as ultralight or light sport aircraft. Here the air is effectively incompressible, meaning flow physics wise, the reynolds number is dominant in determining flow separation. And because of that, all a 1/4 scale model has to do is fly four times faster to get the same flow separation characteristics as the full scale aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So for an ultralight aircraft, which is speed capped at 30 m/s, a 1/4 scale model would have to fly at 120 m/s to see similar stall behavior, which is at the bottom end of where the flow starts to become compressible, meaning most of the flow structures seen at full scale will be seen at the model scale. Accounting for the lower moment of inertia of the model, the spin behavior of the model should predictably scale to reveal the behavior of the full scale aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, what am I getting wrong in my reasoning? Why can't this work?&lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2017-02-25T11:57:46.110" Title="Why can't model aircraft be used to discover spin and stall behavior of manned aircraft designs?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21647" PostTypeId="1" CreationDate="2015-10-06T00:06:28.090" Score="12" ViewCount="1255" Body="&lt;p&gt;X-Plane is built on something called blade element theory. From my understanding, it says the aircraft performance can be found if the performance of 2D cross sections are calculated and integrated in real time. Laminar Research (the maker of X-Plane) uses that as a selling point for X-Plane, saying it can be used to help aircraft designers try out their designs in flight on the computer before building prototypes. However, as commentators on this forum have written before (Peter Kampf), most flight simulators are bad at predicting the performance of the airframe at high angles of attack without using a table of force coefficients generated through windtunnel data or detailed CFD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, what in the flow physics drives this? What part of the physics is modeled incorrectly to give garbage data at high angles of attack? &lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2017-04-30T04:27:43.440" Title="Why are flight simulators bad at predicting drag and lift values at high angles of attack? (the nonlinear flow regime)" Tags="&lt;flight-simulator&gt;&lt;fluid-mechanics&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21648" PostTypeId="2" ParentId="21645" CreationDate="2015-10-06T00:21:53.087" Score="9" Body="&lt;p&gt;FINALLY found it! IT was named using the technical name for blown flaps, 'Circulation Control'. I found it using the search 'state name' stol aircraft. Just so happened I chose the nearly right name first off, 'Virginia'. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/bi3WljC-Rsc?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="11597" LastActivityDate="2015-10-06T00:21:53.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21649" PostTypeId="2" ParentId="21646" CreationDate="2015-10-06T01:15:10.410" Score="10" Body="&lt;p&gt;Scaled models are being used to determine spin characteristics of manned aircraft. For example, see this image from &lt;em&gt;Modeling Flight- The Role of Dynamically Scaled Free-Flight Models in Support of NASA’s Aerospace Programs&lt;/em&gt; by Joseph R. Chambers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x19Uo.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x19Uo.png&quot; alt=&quot;Spin models&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are significant difficulties in correctly modeling the spin characteristics of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a model to properly simulate a full scale aircraft, both should be dynamically similar- i.e. the flight path and angular displacements of the &#xA;model and the aircraft will be identical (geometrically)though the timescale will usually vary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the model faithfully reproducing the aircraft spin characteristics, the (balance of) aerodynamic and inertial parameters should be similar. The model should be scaled (in addition to the geometrical parameters) in the mass, moment of inertia, linear and angular velocity etc. For example, the scaling factors in case of incompressible flow are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1UJvx.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1UJvx.png&quot; alt=&quot;Incompressible Scale&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Modeling Flight- The Role of Dynamically Scaled Free-Flight Models in Support of NASA’s Aerospace Programs&lt;/em&gt; by Joseph R. Chambers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of compressible flow, still more scaling is required:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OQ5ve.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OQ5ve.png&quot; alt=&quot;Compressible Scaling&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Modeling Flight- The Role of Dynamically Scaled Free-Flight Models in Support of NASA’s Aerospace Programs&lt;/em&gt; by Joseph R. Chambers&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue is faithfully duplicating all this scaling is not possible; you are correct that the Reynolds number is the most significant issue involved. Spin involves (partially or fully) separated flows, which are significantly affected by the Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above mentioned report concludes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The data show significant increases in the magnitude and angle of attack for maximum lift as Reynolds number increases from model conditions to the full-&#xA;  scale value. Such results can significantly affect the prediction of flight characteristics of the airplane near and above stall.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another issue is the cost of creating a model; There are significant costs involved in correctly modeling and testing (at-least drop-testing) these systems, the resources for which are not available for all but the most expensive programs. For example, &lt;em&gt;The Spinning of Aircraft- A Discussion of Spin Prediction Techniques&lt;/em&gt;, Report no AD- A216- 200 concludes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The drop-model technique using approximately 1/4 scale-models ... has the potential to cover all phases of the spin. However, because of cost and substantial manpower requirements it only&#xA;  becomes viable for major projects.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These are the reasons we don't see scale models being used to model the spin characteristics of GA and ultralight aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-06T10:32:48.287" LastActivityDate="2015-10-06T10:32:48.287" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21650" PostTypeId="2" ParentId="21647" CreationDate="2015-10-06T03:41:47.197" Score="0" Body="&lt;p&gt;I cannot answer for which CFD model (or strategy/mix thereof) is used by any of the flight simulators.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can say that CFD, in general, is more limited by available resources (FLOPS, and time) than it is about precision. At least, this is the case for a variety of situations in which most flight simulation occurs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Realtime flight simulation (today) must make use of shorthand 'parameterizations' of the simulation grid, in order to resolve model forces at the FPS of the user experience. If the COU (and potentially the GPU) could perform more ops, then the simulation grid could use boxes that are smaller – thus higher resolution and more accurate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Higher spatial resolution simulation grids, along with higher temporal resolution grids, are able to better capture small flow defects. These lead to changes in the flow topology, compression waves, boundary layer separations, and other more complex nonlinearities. &lt;/p&gt;&#xA;" OwnerUserId="57" LastActivityDate="2015-10-06T03:41:47.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21651" PostTypeId="2" ParentId="2065" CreationDate="2015-10-06T03:42:26.387" Score="2" Body="&lt;p&gt;Balked Landing is a very low altitude Go-Around. Not a term you would use with ATC, they don't care. It's a term found in certain aircraft flight manuals and requires a slightly different procedure than a normal go-around, similar to a rejected landing. Usually wheel touchdown is likely and you must verify airspeed increasing past a certain point (safe flap retract speed) and positive rate of climb before de-configuring, otherwise you risk touching down with the gear in transit or slamming down because of loss of lift from flaps/slats. &lt;/p&gt;&#xA;" OwnerUserId="11600" LastActivityDate="2015-10-06T03:42:26.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21652" PostTypeId="2" ParentId="12782" CreationDate="2015-10-06T04:34:40.237" Score="1" Body="&lt;p&gt;The first step would be a BWB military transport.&#xA;The X48B / X48C scaled drones helped understand many issues associated with control.&#xA;The B2 bomber cost was mostly a result of early stealth materials, early large scale usage of composites. If a B2 were to be re-engineered with current stealth materials and reduced composite costs it would cost a fraction of that value to build.&#xA;The remaining substantial challenge with large BWB aircraft is pressurization.&#xA;The tube and wing shape is much easier to pressurize (wing isn't pressurized tube is one of the easiest shapes to pressurize).&#xA;BWB aircraft appears to have larger surface, but that's not true compared to an aircraft with the same cargo/pax capacity. Also what matters isn't total surface area but rather total lift vs total drag. A high lift body with less drag : lift ratio allows for higher altitude cruising which would greatly reduce fuel requirements.&#xA;BWB airliner proposed is about the same as a A380, with a much shorter length, much wider cabin, ability to carry cargo further out into the wing.&#xA;An A380 has 4 fairly large turbofan engines. A BWB the same size would have 3 similarly sized turbofans in the aft fuselage.&lt;/p&gt;&#xA;" OwnerUserId="11604" LastActivityDate="2015-10-06T04:34:40.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21653" PostTypeId="1" CreationDate="2015-10-06T05:02:00.423" Score="6" ViewCount="2129" Body="&lt;p&gt;Do aircraft designers look at the ratio of how much fuselage surface area can be loaded onto a given unit of wing and tail surface area including elevator, aileron, rudder etc? (Possibly, the surfaces of propellers and internal parts of jets, may be excluded while making such calculations.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there such a parameter, and if so, what are the normal values?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is for normal fixed-wing and rotary-wing aircraft, and mostly commercial aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is NOT about fighter jets, space-shuttles, canard-wing designs, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flying_wing&quot; rel=&quot;nofollow&quot;&gt;flying wings&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lifting_body&quot; rel=&quot;nofollow&quot;&gt;lifting body&lt;/a&gt; and other cutting-edge-technology stuff.&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="14897" LastEditDate="2020-01-12T13:31:49.560" LastActivityDate="2020-01-12T13:31:49.560" Title="Is there a parameter that links the areas of the fuselage and control surfaces?" Tags="&lt;aircraft-design&gt;&lt;fuselage&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2015-10-06T14:58:24.217" ContentLicense="CC BY-SA 4.0" />
  <row Id="21655" PostTypeId="2" ParentId="21633" CreationDate="2015-10-06T07:04:22.650" Score="19" Body="&lt;p&gt;I always track my flights, so here is my experience:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;App using offline maps&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As it has been said, you will need an app which can download maps prior to the flight. I never had a flight with onboard wifi, but I guess, there's usually a data volume constraint, which could make it expensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I use &lt;a href=&quot;https://play.google.com/store/apps/details?id=com.mapfactor.navigator&amp;amp;hl=en&quot; rel=&quot;noreferrer&quot;&gt;Mapfactor Navigator&lt;/a&gt; (Android), which is an offline navigation system for cars etc. &#xA;The maps can be obtained from within the app, the user has the choice between free maps from the &lt;a href=&quot;http://www.openstreetmap.org/&quot; rel=&quot;noreferrer&quot;&gt;OpenStreetMaps&lt;/a&gt; project and TomTom maps, which you have to pay.&#xA;The maps can be downloaded per country, and big maps are subdivided into smaller pieces. For example, the very detailed map for Germany is divided into four parts, together about 0.8GB of data. The entire USA can be downloaded per state, all together 1.7GB.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible to configure several fields at the bottom of the screen to display speed, altitude, GPS coordinates, distance to destination and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mainly use this app to explore a country (e.g. by car) on vacation, but it's also fun to use it on board to see what's that location below us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may switch off speed camera warning. I once got a warning over Switzerland. The 840km/h were well above the max speed limit of 120km/h, and the fine should have been in the order of seizing all property of the airline. For some reason, the pilot didn't care...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OK, lots of advantages, but there's also a drawback: The app can not just record your flight, though a menu for tracking exists. Nor can it display your currently covered track. It can only record a track when it's navigating you, but you don't want to hear &quot;turn around! turn around!&quot; all the time...&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Tracking app&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Again, there should be thousands of apps out there. I'm using &lt;a href=&quot;https://play.google.com/store/apps/details?id=nl.sogeti.android.gpstracker&amp;amp;hl=en&quot; rel=&quot;noreferrer&quot;&gt;Open GPS Tracker&lt;/a&gt;, which can also display your position / track on an &lt;em&gt;online&lt;/em&gt; map. So, you just see a point moving on a gray screen while flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this app allows to record your track, with up to one point per second, and at the end, you can export it as GPX file, which is &lt;em&gt;the&lt;/em&gt; standard. It can be opened by many map tools, also by googles MyMaps or what it's called. The file contains coordinates, precision, time, altitude, speed, number of satellites and course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One hint: This app makes a sanity check between speed reported by the GPS module and speed calculated from recorded points. If this fails, it doesn't display/record any speed. This often happens onboard, so switch this check off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a flight from Düsseldorf (DUS) to Las Palmas, Gran Canaria (LPA), including altitude profile, drawn with Marble (Linux KDE program):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/XdBFU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XdBFU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Precision&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An airliner is usually made of aluminum, which makes it a huge faraday's cage. The reception of any radio waves is very limited (through the windows), and so is GPS. &#xA;And as GPS needs a line of sight to several satellites spread as much as possible over the entire sky, the only chance is to have a window seat. There, I usually get a very good GPS signal, while it's already very bad to unusable on the next seat, and don't even think about it on the aisle seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having a window seat, I usually get a good signal. While taxiing, the precision is quite good, as on this flight from Frankfurt (FRA):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mFUe9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mFUe9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the strength and accuracy of the GPS signal relies on the quality of the GPS module of your phone. My last phone wasn't so good, I often had jumps of several 100m sidewards, or from 7000m to 10000m altitude. This is just because accuracy comes with the number of satellites, which usually increases with altitude. And: The first aim of GPS is to locate your position, the altitude usually is less important. With my current phone, I don't see such problems. No sudden steps aside, and altitude and speed were quite the same as displayed on the entertainment system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, not entirely. I noticed my phone showing an altitude about 50m too high when landing on my last flight. The 20m shown by the entertainment system were plausible, as the airport was nearly on sea level / in the sea. But the too high altitude was still there, even at the beach. Keep in mind the earth isn't a sphere, it's an ellipsoid, though even that's not correct, it's more like a potato. So, sea level isn't the same everywhere. High quality/price GPS receivers know this and contain data to compensate it, but cheap ones just use the ellipsoid model. (However, 50m is nothing during flight, and what do you expect from a phone inside the cabin...)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;More hints&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For a working GPS, the receiver needs a list of all GPS satellites and their precise orbits (&quot;almanach&quot;), current time and its rough position. If it does not have its rough position, it takes much more time to get a fix (first GPS position). And if it doesn't have a recent almanach, it has to listen to the satellites for a while, as they slowly broadcast it.&lt;br&gt;&#xA;As reception of radio signals is quite difficult inside the cabin, it may be very hard to get a fix, and even impossible to get the almanach.&lt;br&gt;&#xA;So, it's good practice to prepare your phone before the flight, as reception will be better, and assisted-GPS allows to retrieve the almanach and current position via the mobile network.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally: The battery.&lt;br&gt;&#xA;Running my two apps on a 4.5h flight takes about 80% battery, and I have a laaarge battery. Of course, this also depends on display-on time. But the endurance could by tested before the flight, and if it's too short, a power bank my help.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2015-10-06T07:04:22.650" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21656" PostTypeId="1" CreationDate="2015-10-06T07:56:17.433" Score="9" ViewCount="3685" Body="&lt;p&gt;I have visited and flown out of Harare International Airport, Zimbabwe a number of times and the thing that always baffles me is: Why do aircraft use runway 23 to depart, but runway 05 to land?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first I've thought that it may be a wind change, but it appears it's not the case. Is it because wind is limited at the airport and therefore direction does not matter? Or is there some special procedure for 'hot/high' airports?&lt;/p&gt;&#xA;" OwnerUserId="11606" LastEditorUserId="572" LastEditDate="2015-10-06T13:41:24.320" LastActivityDate="2018-08-07T18:58:39.577" Title="Why would aircraft take-off in the opposite direction as landing despite wind direction?" Tags="&lt;landing&gt;&lt;airport&gt;&lt;takeoff&gt;&lt;runways&gt;&lt;wind&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21657" PostTypeId="2" ParentId="21653" CreationDate="2015-10-06T07:58:27.607" Score="6" Body="&lt;p&gt;The engineer strives to give the aircraft a positive $c_{n_{\beta}}$ by adjusting the size of the vertical tail. A good value is $c_{n_{\beta}} = 0.1$ when the reference length is the wingspan, or $c_{n_{\beta}} = 0.2$ when the half span is used as reference length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is just a fancy way of saying that the aircraft should have natural weathervane stability and correct sideslip angles by turning into the wind. A fuselage by itself is mostly unstable, because the &lt;a href=&quot;https://aviation.stackexchange.com/questions/6302/how-to-find-the-location-of-the-aerodynamic-centre/6338?s=1%7C0.1449#6338&quot;&gt;aerodynamic center of slender bodies&lt;/a&gt; is located close to their tip. Any side force on the fuselage will thus act ahead of the center of gravity. A compensating force acting behind the center of gravity is needed. Since not the forces themselves, but rather their moments around the center of gravity count, you cannot simply compare areas, but the product of area, lever arm and &lt;a href=&quot;https://aviation.stackexchange.com/questions/14508/calculating-a-finite-wings-lift-from-its-sectional-airfoil-shape/14559?s=1%7C0.2933#14559&quot;&gt;lift curve slope&lt;/a&gt;, which in turn is determined by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056?s=4%7C0.0652#5056&quot;&gt;aspect ratio&lt;/a&gt; of the area concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher aspect ratio of a vertical tail surface (higher at least when compared to the fuselage) will allow to make the tail smaller, but causes an earlier stall of the vertical tail. As a consequence, the stabilizing side force on the tail stops to increase at a sideslip angle where the destabilizing side force on the fuselage will still blithely increase with sideslip angle. To improve stability at high sideslip angles, &lt;a href=&quot;https://aviation.stackexchange.com/questions/11808/why-do-some-airplanes-have-vertical-strakes/11812?s=3%7C0.1708#11812&quot;&gt;strakes&lt;/a&gt; are added ahead of the vertical tail. Their surface will do little at small sideslip angles, but be very important at higher angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, comparing areas is not enough. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-10-07T22:54:26.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21658" PostTypeId="2" ParentId="21653" CreationDate="2015-10-06T08:05:56.617" Score="8" Body="&lt;p&gt;I do not know a method that relates the fuselage area to empennage sizes, but there is rule that can be used to estimate the size of the vertical and horizontal tail. It is using the so called tail volume coefficient. For the horizontal tail given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ V_h = \frac{S_h \cdot l_h}{S c} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With $V_h$, the horizontal tail volume coefficient, $S_h$ the horizontal tail surface, $l_h$ the horizontal distance between the c.o.g. and the tail, $S$ the wing area and $c$ the average wing chord.&#xA;Basically, this coefficient says that the moment induced by the wing scales with $S$ and $c$, whereas the counteracting moment given by the tail scales with the area of the horizontal wing multiplied by the distance to the c.o.g., and that there should a certain ratio between the two. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A well behaved aircraft typically has a $V_h$ which falls in the following range $^{[1]}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_h = 0.30 ... 0.60$$&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If $V_h$ is too small, the aircraft’s pitch behavior will be very&#xA;  sensitive to the CG location. It will also show poor tendency to&#xA;  resist gusts or other upsets, and generally “wander” in pitch&#xA;  attitude, making precise pitch control difficult. $^{[1]}$&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We can check the values for some commercial aircraft &lt;a href=&quot;http://booksite.elsevier.com/9780340741528/appendices/data-a/table-1/table.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; (I chose Airbus, but it should hold for others as well) :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{array}{|c|c|} \hline&#xA; \text{Model} &amp;amp; \text{$V_h$} \\ \hline&#xA;\text{A330-200} &amp;amp; 0.957 \\ \hline&#xA;\text{A330-300} &amp;amp; 0.791 \\ \hline&#xA;\text{A340-200} &amp;amp; 0.733 \\ \hline&#xA;\text{A340-300} &amp;amp; 0.791 \\ \hline&#xA;\text{A340-500} &amp;amp; 0.729 \\ \hline&#xA;\text{A340-600} &amp;amp; 0.729 \\ \hline&#xA;\end{array}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that the values are already higher than given by the guideline, showing the issue of the generalization.&#xA;Another fact that causes the deviations, is the fact that the Airbus aircraft are designed in families. Thus, they design an aircraft, and then add some extra fuselage length to generate a larger family member. This will possibly drive the tail volume coefficient away from the ideal case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the vertical tail there is an equivalent form:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V_v = \frac{S_v l_v}{S b}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With $V_v$, the horizontal tail volume coefficient, $S_v$ the horizontal tail surface, $l_v$ the vertical distance between the c.o.g. and the tail, $S$ the wing area and $b$ the average wing span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A well behaved aircraft typically has a $V_v$ which falls in the following range $^{[1]}$&#xA;$$V_v = 0.02 ... 0.05$$&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If $V_v$ is too small, the aircraft will tend to oscillate or “wallow” in yaw as the pilot gives rudder&#xA;  or aileron inputs. This oscillation, shown in Figure 5, is called Dutch Roll, and makes precise&#xA;  directional control difficult. A Vv which is too small will also give poor rudder roll authority in an&#xA;  aircraft which uses only the rudder to turn. $^{[1]}$&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again checking the values:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{array}{|c|c|} \hline&#xA; \text{Model} &amp;amp; \text{$V_v$} \\ \hline&#xA;\text{A330-200} &amp;amp; 0.057 \\ \hline&#xA;\text{A330-300} &amp;amp; 0.059 \\ \hline&#xA;\text{A340-200} &amp;amp; 0.055 \\ \hline&#xA;\text{A340-300} &amp;amp; 0.059 \\ \hline&#xA;\text{A340-500} &amp;amp; 0.049 \\ \hline&#xA;\text{A340-600} &amp;amp; 0.049 \\ \hline&#xA;\end{array}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here the values are quite close to the general guideline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another interesting plot is shown by &lt;a href=&quot;http://adg.stanford.edu/aa241/stability/taildesign.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;This tail design page by Stanford&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here it shows that the tail volume correlates quite nicely to fuselage height and length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bqLUT.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bqLUT.gif&quot; alt=&quot;Correlation&quot;&gt;&lt;/a&gt;&#xA;Image showing correlation of aircraft vertical tail volume as a function of fuselage maximum height and length.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted that aircraft aren't really designed by these guidelines anymore, all the control surfaces are designed such that they provide the control authority necessary, not to match a general rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$^{[1]}$: Lab 8 Notes – Basic Aircraft Design Rules &lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-01-unified-engineering-i-ii-iii-iv-fall-2005-spring-2006/systems-labs-06/spl8.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2017-01-03T09:43:07.870" LastActivityDate="2017-01-03T09:43:07.870" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21659" PostTypeId="2" ParentId="21656" CreationDate="2015-10-06T09:11:14.443" Score="5" Body="&lt;p&gt;Wind direction does matter! Just to make that clear from the start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Harare Airport is located at an elevation of 1490m MSL, and Zimbabwe is in tropical region, which classify the Airport in hot and high conditions. That's also why Harare has one of the longest runways in Africa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I understand it, pilots are required to follow standard procedures, but on some specific conditions, they are able to submit a request for special ones (or suggested by controllers). To list a few :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;start take off roll from runway entry instead of from one end of runway (to save time when late on schedule, to ease traffic flow, to avoid a runway backtrack when no taxiway leads to runway start while an aircraft is on an approach pattern, etc.)&lt;/li&gt;&#xA;&lt;li&gt;downwind take off (similar to above, or last take off(s) after a wind change, etc.)&lt;/li&gt;&#xA;&lt;li&gt;take off from the runway that shortens flightplan length/duration (there are specific paths you must follow (waypoints) to exit the area of an airport, and reach the air routes toward destination. There are also forbidden areas like cities or military/restricted zones you have to avoid). Obviously, taking off direction matters.&lt;/li&gt;&#xA;&lt;li&gt;on a calm day with clear visibility and nearly no wind, on an airport with not that much traffic, you have much more opportunity to select a preferred runway depending on the flightplan.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are also some cases where you can land from one runway end and take off from the other. I don't know whether Harare suits those cases, but there are several airports in the world which are. Obviously the ones that have closed runway on one end like Lukla (VNLK) or Courchevel, but you also have Nosy Be (FMNN) and Antsiranana (FMNA) in Madagascar which aren't, to name those I know well, and another one that is closed: Kai Tak (VHHH) in Hong Kong. Reasons vary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Terrain. When you have mountains right in the take off path.&lt;/li&gt;&#xA;&lt;li&gt;Winds, likely to come from one side along the year, that you can neglect on landing on calm days, but not on take off.&lt;/li&gt;&#xA;&lt;li&gt;Lack of Navigation support from one end of the runway (ILS/PAPI/VASI/VOR/DME...)&lt;/li&gt;&#xA;&lt;li&gt;Restricted area (City, Military bases, highly secured facilities, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Gates/parking spots location: when they are near the end of one runway, take offs are likely to start there, and landing to occur from the other end, when possible.&lt;/li&gt;&#xA;&lt;li&gt;noise abatement : landings can be tolerated from one end, but not take offs.&lt;/li&gt;&#xA;&lt;li&gt;etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, sum the above for Harare:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you have such a long runway that sometimes, not all aircraft are required to take off from one end. Reciprocally, you have to taxi longer to reach Rwy23 for take of, and taxi back longer to reach the terminal if you landed on Rwy05.&lt;/li&gt;&#xA;&lt;li&gt;you have many airlines operating there, but there is not that much activity as on platforms like JFK, Manchester, Singapore Changi or Sydney.&lt;/li&gt;&#xA;&lt;li&gt;you have airliners, commuters, general aviation and military; large, medium and small aircraft. Depending on their flightplans and the weather condition, you can expect to have take offs and landings from both directions, anytime.&lt;/li&gt;&#xA;&lt;li&gt;you're in Africa, where rules are less strict than anywhere else (good or bad ? I don't know)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, when winds are calm, visibility clear enough, runway long enough for a given aircraft to take off from a specific point, you can expect pilots to select the best runway that fits their flightplans. This does not happen only in Harare, it happens on a daily basis, like on my home airport as well, Antananarivo Ivato (FMMI/TNR):&lt;br&gt;&#xA;Due to winds direction mostly coming from east, take off are expected to occur from Rwy11. But, small airliners like ATR or some 737/ERJs doesn't backtrack Rwy11 at all. Only &quot;visitors&quot; backtrack the runway. Medevac small aircraft (Cessna 206B, Learjet 31, King Air) usually land from the runway that suits their flightplans. A few minutes later, a DHC6 takes off downwind (Rwy29) because the destination is to the west. Then a 777F of Air France lands on Rwy11. And so on while the terminal is right in the middle between the two ends of the runway, and it's only 3100m long.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;By the way, pilots or controllers don't just do what they want. Every decision is taken with the uttermost professionalism and care, and whenever that is required, this is registered in log books, or a clearance is requested, and granted beforehand. That means almost all, if not all, activity you may spot on Harare are known and defined procedures. It's highly unlikely a pilot would perform a procedure not written anywhere (the agency/organization in charge of navigation safety in the country is responsible for providing standard procedures).&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="28837" LastEditDate="2018-08-07T18:58:39.577" LastActivityDate="2018-08-07T18:58:39.577" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21660" PostTypeId="2" ParentId="21647" CreationDate="2015-10-06T10:21:35.137" Score="0" Body="&lt;p&gt;I'm sorry, I can't answer the physics part. It may be a good question on &lt;a href=&quot;https://physics.stackexchange.com/&quot;&gt;Physics StackExchange&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a programming point of view (SuperUser ?):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Floating points calculations are among the most CPU intensive.&lt;/li&gt;&#xA;&lt;li&gt;Precision matters when you talk about physics behaviour. Without enough precision, some parameters may jump from one value to an exaggerated one, even to the opposite value (stackoverflow), even if it's the next available value that can be stored in bits. All a computer can do are approximations.&lt;/li&gt;&#xA;&lt;li&gt;Cycle update/refresh cycle, or interval duration between states changes in physics parameters. 10 milliseconds may look really small and good at simulating physics properties. However, bring the aircraft in stall conditions and you realize that 10ms is not enough to accurately resolve all surface components efficiency on a normal computer. That's why on some simulator, especially the old ones, you have unexpected aircraft behavior like brutal rolls/pitches/yaws.&lt;/li&gt;&#xA;&lt;li&gt;Race condition. This is a situation of concern on parallel tasks made by the computer. Simply put, one task is to calculate vector forces applied on the aircraft. Another parallel task is user or autopilot inputs. And another task is to generate new airflow conditions, like gusts and turbulences. Those are not synchronized. The more the tasks, the othen asyncronuous computations occur.&lt;/li&gt;&#xA;&lt;li&gt;A computer just does what it has been taught to do. The aircraft can break if the value of one parameter goes beyoud a certain limit, and a brutal overreaction is induced by one miscalculated parameter (due to the refresh cycle above, or obsolete parameters due to the async multi tasks) Some damping fallbacks checks can be added in the code (like on computer driven pilots inputs), but this also add more computations to perform on user computer where the simulator is installed.&lt;/li&gt;&#xA;&lt;li&gt;Random update. To make turbulences for instance, you have to create dynamic random parameters whose bounds changes depending on weather conditions, altitude, geographic locations, etc. This adds to the overall computations to perform.&lt;/li&gt;&#xA;&lt;li&gt;By the way, the simulator has to render graphic datas on screen and handle thousands objects with millions of parameters. That's also why, unlike X-Plane of FSX/P3D, real professional simulators doesn't care much about sceneries objects (traffic) and other eye candy like clouds beautifulness or sun glare. Because physics computations are prioritized.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's not that the datas are corrupted or miscalculated. They are 1) approximations as results of very simplified formulas or lookup tables/matrices to speed up computation time, and 2) are not always updated at the very moment they are most required (high AOA) because of excessive task to perform to update them. Adding a parameter (like an extra wing fence above the wing) and computations to perform on each update may increase linearly or exponetially. The physics model is not incorrect, but is not the most accurate one either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, one can get near to the best possible approximation, but at the cost of computation time. We often hear a computer took x weeks to calculate y trillions decimals of Pi, or z days to display an accurate overview of our galaxy colliding with M31 Andromeda. Getting there is possible, but not yet through mass public simulators like X-Plane, FSX or P3D. Common computers are not powerfull, fast and precise enough yet, to reproduce realtime physics behaviors that complex like aerodynamics or gravity.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2015-10-06T10:21:35.137" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21661" PostTypeId="2" ParentId="21647" CreationDate="2015-10-06T10:28:10.780" Score="11" Body="&lt;p&gt;Laminar flow is &lt;strong&gt;easy&lt;/strong&gt;. While there is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Navier%E2%80%93Stokes_equations&quot; rel=&quot;noreferrer&quot;&gt;complete set of differential equations&lt;/a&gt; that describes any fluid flow, there is a wealth of simplifications and assumptions that you can use on laminar flow. This means that X-Plane doesn't need to model all the air around the wing, but can do the calculations based on wing profile and local velocities. Everything is relatively linear, so you can just change some variables and use predetermined parameters. Furthermore, it's completely time-invariant in steady state. You can now easily solve the equations, integrate the calculated pressure profile along the wing, and done!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For turbulent flow, none of that holds. The current way of simulating turbulent flow is to do a &lt;a href=&quot;https://en.wikipedia.org/wiki/Finite_element_method&quot; rel=&quot;noreferrer&quot;&gt;Finite Element&lt;/a&gt; analysis or similar (e.g., &lt;a href=&quot;https://en.wikipedia.org/wiki/Finite_difference_method&quot; rel=&quot;noreferrer&quot;&gt;FDM&lt;/a&gt;). Basically, you will need to consider &lt;strong&gt;all&lt;/strong&gt; the air in a large volume around the wing, divide it up in a small grid and simulate it. For a good calculation, this takes in the order of seconds to minutes for a single 2D cross-section on my pretty decent laptop. And then we're neglecting the 3D influences. Furthermore, turbulent flow changes w.r.t. time. For example, open your car window on the highway - you will hear the wind roar and pulsate. This means that you will need to get your previous pressure- and velocity field, and use that as a starting point for your next FEM/FDM analysis. Finally, turbulent flow is extremely hard to predict correctly, even with above methods: a slightly rougher surface, a small bolt or a small wind gust can delay flow separation for a few inches, completely invalidating your results. Perhaps &lt;a href=&quot;https://www.youtube.com/watch?v=nzNx0NRk7-8&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; YouTube video (note: this is &lt;strong&gt;not&lt;/strong&gt; simulated in real time!) might shed some light on the vast complexity and time-dependency of turbulent flow - and remember that your horizontal stabilizer will see disturbed air in stall conditions, making it necessary to simulate the &lt;strong&gt;entire&lt;/strong&gt; flow field around the airplane for a correct simulation, not just the wing sections. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, X-plane has a framerate measured in frames per second, not frames per hour. This means that they use a bunch of assumptions to calculate the wing lift. I'm guessing they just have some values for location of flow separation and turbulent pressure for some fixed velocities and angles, and interpolate to the actual values. My guess is that they also have some parameters that aren't actually calculated, but are chosen such that some very basic maneuvers are possible like spin recovery, regardless whether these values correspond to any actual physical phenomena - it's a game, after all.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2017-04-26T08:36:29.237" LastActivityDate="2017-04-26T08:36:29.237" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21662" PostTypeId="2" ParentId="21646" CreationDate="2015-10-06T10:30:31.690" Score="18" Body="&lt;p&gt;Who says scale models cannot be used for spin modeling?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key information is that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;noreferrer&quot;&gt;Reynolds number&lt;/a&gt; does not affect the behavior of separated airflow as much, so you do not need to increase speed to compensate for the smaller dimensions. Only when the stall behavior is studied would the Reynolds number matter, but here also meaningful results are possible at lower speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Models are routinely used in &lt;a href=&quot;http://crgis.ndc.nasa.gov/historic/20-Foot_Spin_Tunnel&quot; rel=&quot;noreferrer&quot;&gt;spin tunnels&lt;/a&gt;. Here both the speed and the dimensions are smaller, but the results can be transferred to the original aircraft. There are two sorts of spin tunnels:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Free tunnels with an open, divergent section in which the model has to be thrown by a skilled operator so it will settle in a spin within the upwards flowing air stream. The section is divergent, so the speed changes with height and allows the model to find a matching speed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pRKWO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pRKWO.jpg&quot; alt=&quot;Spin tunnel test in 1959&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture from spin tests on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_E-2_Hawkeye&quot; rel=&quot;noreferrer&quot;&gt;Grumman E-2&lt;/a&gt; model in the NACA 20 foot spin tunnel (picture &lt;a href=&quot;http://crgis.ndc.nasa.gov/historic/File:L-59-6221.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Closed tunnels in which the model is mounted on a sting. The sting is connected to a rotating balance, which can be set at different roll and yaw rates. The resulting matrix of coefficients over angle of attack, angle of sideslip and over the three rotation speeds is fed into a computer model which computes the equilibrium points.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The models used in free tunnels must be scaled both geometrically and inertially, so their mass distribution matches that of the original. If the spin tunnel uses a rotating balance, not even the dynamic scaling of masses and inertias is needed, and a regular tunnel model can be used. However, if the resulting spin is of an oscillating nature, the free spin tunnel is at an advantage, because this becomes readily apparent in the test. In a closed tunnel you just get two equilibrium points and must make the connection yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A third way are free-flight tests of models, but they are much more expensive and allow less observations than wind tunnels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall characteristic is a little harder to predict using models, but again you can draw conclusions from what can be seen in the tunnel. To arrive at the maximum lift coefficient starting from the measured value at Re = 1,000,000, you may use this scaling: $$\Delta c_{L_{max}} = \frac{log_{10}\left(Re^{\frac{1}{6}}\right)}{3.5}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plot below shows the difference in lift coefficient between a small model and a full-scale airplane. The biggest differences are around stall, and at the high angles of attack seen in spins both show fairly similar behavior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zM2W2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zM2W2.png&quot; alt=&quot;Lift coefficient over angle of attack&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift coefficient over angle of attack for model and full-scale aircraft, taken from Joseph Chambers' monograph on testing with models (&lt;a href=&quot;http://www.nasa.gov/pdf/483000main_ModelingFlight.pdf&quot; rel=&quot;noreferrer&quot;&gt;Modeling flight : the role of dynamically scaled free-flight models in support of&#xA;NASA’s aerospace programs&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small aircraft, the relative expense of a tunnel test is normally inadequate. Instead, the real thing is used. Since the speeds involved are small, spin tests are carried out with a spin chute or a releasable mass at the tail of the aircraft. On modern designs, even a full-aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/Ballistic_parachute&quot; rel=&quot;noreferrer&quot;&gt;ballistic parachute&lt;/a&gt; system can be employed to prevent a crash if the spin test ends in an unrecoverable situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5aZkF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5aZkF.jpg&quot; alt=&quot;Spin chute installation on a Columbia 400&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spin chute installation on a Columbia 400 (picture &lt;a href=&quot;http://www.caro-engineering.com/PastProj_files/image059.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="556" LastEditDate="2017-02-25T11:57:46.110" LastActivityDate="2017-02-25T11:57:46.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21663" PostTypeId="2" ParentId="21656" CreationDate="2015-10-06T11:03:44.647" Score="12" Body="&lt;p&gt;Apparently, only the &lt;a href=&quot;http://airportguide.com/airport/Zimbabwe/Harare/Harare-FVHA-HRE/runways.php&quot;&gt;05 runway&lt;/a&gt; has &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway#Runway_markings&quot;&gt;precision approach markings&lt;/a&gt; and (Medium Intensity) &lt;a href=&quot;http://code7700.com/approach_lighting_system.html&quot;&gt;Approach Lighting System&lt;/a&gt; (MALS). Runway 23 has non-precision approach markings and no Approach Light System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the aircraft only land on runway 05. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-06T11:03:44.647" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21664" PostTypeId="1" AcceptedAnswerId="21685" CreationDate="2015-10-06T11:07:24.857" Score="45" ViewCount="11161" Body="&lt;p&gt;I'm currently studying for my PPL and one of the accepted textbooks contains the following disclaimer at the end of the Principles of Flight section on lift:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is important to note that the forgoing explanation of lift, and its reliance on Bernoulli's theorem, is very much the 'classical' theory of lift production and the one on which the exam questions are usually based. There are differences of opinion amongst scientists on the subject....[snip]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same book previously also describes the venturi theory which NASA discredits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, one of my previous CFI's told me that during a previous successful job interview he had been asked to explain lift and had merely responded with &quot;Which theory would you like me to cover?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary - we must have an excellent understand of some components because of the way we're able to design and build such stable (and unstable when we want) aircraft. Plus, I see some absolutely incredible mathematics described on this website which seek to accurately answer complex questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question isn't how is lift generated -it's how complete is our understanding? Which bits are still in dispute, and which bits are fully accepted?&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2020-10-30T12:33:13.460" Title="How complete is our understanding of lift?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="8" CommentCount="18" FavoriteCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="21665" PostTypeId="1" AcceptedAnswerId="22111" CreationDate="2015-10-06T12:07:53.257" Score="23" ViewCount="1315" Body="&lt;p&gt;When entering waypoints into an FMS, the FMS calculates bearing and distance between them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it use &quot;normal&quot; spherical trigonometry equations, or go for the more accurate &lt;a href=&quot;https://en.wikipedia.org/wiki/Vincenty&amp;#39;s_formulae&quot;&gt;Vincenty algorithm&lt;/a&gt; which takes the earth to be an oblate spheroid?&lt;/p&gt;&#xA;" OwnerUserId="8681" OwnerDisplayName="user11612" LastEditorUserId="572" LastEditDate="2015-10-06T13:39:56.360" LastActivityDate="2017-11-09T07:49:47.183" Title="Which trigonometric algorithm does an FMS use to determine distance between waypoints?" Tags="&lt;fms&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21666" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T12:30:45.977" Score="18" Body="&lt;p&gt;From &lt;a href=&quot;http://home.comcast.net/%7Eclipper-108/lift.pdf&quot; rel=&quot;noreferrer&quot;&gt;this paper&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The principle of&#xA;equal transit times holds only for a wing with zero lift. [!!]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The air passes over the wing and is bent down. Newton’s&#xA;first law says that them [sic] must be a force on the air to bend it down (the action). Newton’s third&#xA;law says that there must be an equal and opposite force (up) on the wing (the reaction). To&#xA;generate lift a wing must divert lots of air down.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;So how does a thin wing divert so much air? When the air is bent around the top of the wing, it&#xA;pulls on the air above it accelerating that air downward. Otherwise there would be voids in the&#xA;air above the wing. Air is pulled from above. This pulling causes the pressure to become lower&#xA;above the wing. It is the acceleration of the air above the wing in the downward direction that&#xA;gives lift.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;We (those of us reading this) can conlude the following about our (humanity's in general) understanding of lift:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;We certainly understand it well enough to design aircraft, and there may be overlap with this knowledge in other areas, such as maybe wind-powered generator design.&lt;/li&gt;&#xA;&lt;li&gt;Many &lt;em&gt;believe&lt;/em&gt; we have a fairly complete understanding of lift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The second bullet is not at all in impune the excellent (and challenging!) work done through history in fluid dynamics, aeronautical physics, and aeronautical engineering. It is merely to allow for the possibility of future paradigm shifts in our understanding of those topics, even if those shifts do not affect common design practice or practical discussions of lift. A historical example of that last point would be General Relativity as a paradigm shift in our understanding of gravity, while Newtonian gravitational theory was still used for the moon program and is still widely taught and used for situations not requiring extreme precision.&lt;/p&gt;&#xA;&lt;p&gt;In addition to links in Frederico's comment, see also: &lt;a href=&quot;https://physics.stackexchange.com/questions/290/what-really-allows-airplanes-to-fly&quot;&gt;https://physics.stackexchange.com/questions/290/what-really-allows-airplanes-to-fly&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Edit:&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/bernnew.html&quot; rel=&quot;noreferrer&quot;&gt;This NASA page&lt;/a&gt; discusses the controversy of &amp;quot;Bernoulli versus Newton&amp;quot; and concludes that &lt;strong&gt;both&lt;/strong&gt; explanations of lift are &amp;quot;correct&amp;quot; and that there is even more to it. The Euler Equations and the Navier-Stokes Equations are mentioned. &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/lift1.html&quot; rel=&quot;noreferrer&quot;&gt;This page in the same series on NASA's site&lt;/a&gt; suggest that lift is fairly well understood by experts, but is poorly explained in the majority of popular sources:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;There are many explanations for the generation of lift found in encyclopedias, in basic physics textbooks, and on Web sites. Unfortunately, many of the explanations are misleading and incorrect. Theories on the generation of lift have become a source of great controversy and a topic for heated arguments. To help you understand lift and its origins, a series of pages will describe the various theories and how some of the popular theories fail.&lt;/p&gt;&#xA;&lt;p&gt;Lift occurs when a moving flow of gas is turned by a solid object. The flow is turned in one direction, and the lift is generated in the opposite direction, according to Newton's Third Law of action and reaction. Because air is a gas and the molecules are free to move about, any solid surface can deflect a flow. For an aircraft wing, both the upper and lower surfaces contribute to the flow turning. Neglecting the upper surface's part in turning the flow leads to an incorrect theory of lift.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8848" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-06T12:46:58.890" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21667" PostTypeId="1" CreationDate="2015-10-06T12:51:53.243" Score="9" ViewCount="704" Body="&lt;p&gt;&lt;strong&gt;Where can I find reliable figures about the best glides of Lilienthal and the Wright Brothers (1902 - 1903)?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the sources below it would appear that Lilienthal's most advanced glider was far superior to that built by the Wright brothers in 1902 as the German apparatus was able to fly 1148 ft while the machine made by the Wrights only 600 ft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like the wind tunnel tests done by the Wright brothers in 1901-1902 to find optimal wings did not lead to improvements in lowering the glide angle and so increasing the flight distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1)&lt;em&gt;&quot;Finally Lilienthal become so skilled that he could make his glides in air velocities of 33 feet per second ... Lilienthal carried out more than 1,000 glides and attained distances of 1,148 ft. at a gliding angle of 4 degree from the hill.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://books.google.ca/books?id=Z8PaTOr-jxYC&amp;amp;lpg=PA75&amp;amp;ots=9EEqCSsosJ&amp;amp;dq=lilienthal%20glide%20angle&amp;amp;pg=PA77#v=onepage&amp;amp;q&amp;amp;f=false&quot;&gt;Source&lt;/a&gt;: John H. D. Blanke, &quot;Pioneers in Gliding&quot;, Popular Aviation, pag. 74 - 77, May 1928 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) &lt;em&gt;&quot;World Record Holders&lt;br&gt;&#xA;The improved performance of the 1902 glider finally enabled the Wright brothers to gain extensive practice in the air. During September and October, they made between 700 and 1,000 glides. Flights of 500 feet were common, and a few topped 600 feet. Orville enthusiastically wrote home of their success, “we now hold all records!”&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1902/worldrecord.cfm&quot;&gt;Source&lt;/a&gt;: Inventing a Flying Machine &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking about which glider that had better glide ratio because the Lift/Drag ratio is essential: the higher it is the longer the glide and the less powerful and lighter an engine is needed to make the glider fly horizontally.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-06T14:36:49.887" LastActivityDate="2016-01-22T09:27:02.403" Title="Comparing the Lilienthal and Wright gliders, which one had a better glide ratio?" Tags="&lt;aerodynamics&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21668" PostTypeId="2" ParentId="11967" CreationDate="2015-10-06T14:44:48.953" Score="1" Body="&lt;p&gt;I am told that the hourly and calendar service life of many military helicopters are established by the OEM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under certain circumstances, that can be extended when scheduled &quot;rework events&quot; are accomplished by the manufacturer or a certified facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The military uses industrial rework facilities &quot;depots&quot; to ensure many fuselages remain airworthy beyond established service life. &lt;/p&gt;&#xA;" OwnerUserId="11616" LastActivityDate="2015-10-06T14:44:48.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21670" PostTypeId="1" CreationDate="2015-10-06T14:59:09.660" Score="4" ViewCount="415" Body="&lt;p&gt;I'm sorry if I'll be not so accurate in my description but, please, try to understand &quot;core&quot; of my question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;F-22&lt;/strong&gt;, ignoring high cost of each aircraft, &lt;strong&gt;appear to be a successful project&lt;/strong&gt;, developed and delivered in almost desired timeranges respecting requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I sincerely don't understand &lt;strong&gt;why F-35, that initially was thought to have almost same stealth performances of F-22 but at an individual cheaper cost, is running into troubles, difficulties, risk of abandoment since years&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Develop is still ongoing and reliability and performances are still not satisfied. I thought that experience based on first stealth high perfromance fighter jet could help and speed up an aircraft like f-35 that should have lighter requirements but facts are demonstrating the opposite&lt;/p&gt;&#xA;" OwnerUserId="11089" LastActivityDate="2015-10-06T14:59:09.660" Title="Why developing F-35 is harder than F-22?" Tags="&lt;aircraft-design&gt;&lt;f-22&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-10-06T21:02:38.547" ContentLicense="CC BY-SA 3.0" />
  <row Id="21671" PostTypeId="1" AcceptedAnswerId="21676" CreationDate="2015-10-06T15:00:04.957" Score="2" ViewCount="2045" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The higher aspect ratio of a vertical tail surface (higher at least when compared to the fuselage) will allow to make the tail smaller, &lt;em&gt;but causes an earlier stall&lt;/em&gt;.&#xA;  &lt;br&gt;&lt;sup&gt;-Peter Kämpf said so &lt;a href=&quot;https://aviation.stackexchange.com/a/21657/5517&quot;&gt;here&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How does the &lt;em&gt;vertical&lt;/em&gt; tail, and more specifically, the aspect ratio of the vertical tail, impact stall?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-10-07T14:52:15.437" Title="How does the aspect ratio of the vertical stabilizer affect stall speed?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21672" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T15:07:42.210" Score="14" Body="&lt;p&gt;The problem here is that &quot;correlation does not imply causation&quot;. Neither Bernouilli's principle nor Newton's laws of motion &lt;em&gt;explain&lt;/em&gt; lift. Both of them give valid methods of &lt;em&gt;calculating&lt;/em&gt; the lift force from the air flow pattern around the wing, but neither of them explain &lt;em&gt;why the flow pattern is what it is&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideas like &quot;equal transit time&quot; at least &lt;em&gt;try&lt;/em&gt; to give a reason &quot;why,&quot; but experiments which visualize the flow pattern with smoke demonstrate that is just &lt;em&gt;wrong&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best &quot;one-word explanation&quot; of what causes lift is the &lt;strong&gt;viscosity&lt;/strong&gt; of the air. Viscosity is the reason why there can't be any &lt;em&gt;discontinuities&lt;/em&gt; in the overall flow pattern*. In particular, the air velocities on either side of the relatively sharp trailing edge of the wing have to be the same, otherwise the effect of viscosity at that point would propagate &lt;em&gt;upstream&lt;/em&gt; through the air (at the speed of sound) and change the global flow pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there were no viscosity, no wing of any shape would produce any lift, or any drag force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Let's limit this discussion to subsonic flows. Introducing shock waves into the airflow makes a &quot;hand-waving&quot; non-mathematical discussion more complicated, but it doesn't invalidate the essential point I'm trying to make.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-10-06T15:07:42.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21673" PostTypeId="2" ParentId="21619" CreationDate="2015-10-06T15:24:42.243" Score="3" Body="&lt;p&gt;The B52 does &quot;rotate&quot; on takeoff just not to the degree of what seems normal for such a large jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All airplanes must produce lift that is greater than the opposing force of gravity/its weight for it to leave the runway. When lift = weight/gravity the airplane is in a stable state, which means the rate of climb or descent will be constant. This means unless the lift exceeds the weight an airplane will never leave the ground. Once in flight the airplane's rate of climb stabilizes, or becomes constant when lift = gravity/weight (the opposing force).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is it only appears the B52 is not rotating. The pilots are applying &quot;up&quot; elevator and increasing the angle of attack of the wing, thus increasing lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will throw a correction to an answer given above:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CG, center of gravity, is fixed and unless a weight/load moves within the airplane it never changes. Examples of things which would change an airplanes CG are fuel burn off, bomb dropped, or a cargo shift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the elevator is moved the airplane &quot;pitches&quot; up, because the tail (horizontal) stabilizer is producing &quot;negative&quot; lift (it pushes down on the tail), and rotates the airplane along the CG. The placement of the landing gear actual opposes the rotation of the airplane in most designs. The change in &quot;angle of attack&quot; of the wing due to the pitching up increases the lift produced by the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The placement of the landing gear is a compromise based on the design of the airplane. The B52 and its tandem wheel set is a compromise because of the wing and body design of the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add one more thing to prevent confusion:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airplane &quot;rotates&quot; for takeoff the force (or weight) of the horizontal stabilizer must be greater than the weight of the airplane in front of the rear most wheels for the airplane to &quot;pitch up.&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most (if not all) large transport type large airplanes the whole horizontal stabilizer (compared to just the elevator on smaller airplanes) is trimmed for take off to provide a &quot;neutral&quot; force for the desired takeoff speed. If the stabilizer trim is set incorrectly there may not be enough &quot;elevator&quot; to either pitch up or to prevent a spontaneous un-commanded pitch up of the airplane. Both are disastrous and the results of which can be found on youtube.&lt;/p&gt;&#xA;" OwnerUserId="11618" LastEditorUserId="11618" LastEditDate="2015-10-06T15:52:35.330" LastActivityDate="2015-10-06T15:52:35.330" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21674" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T15:32:48.640" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How complete is our understanding?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Complete enough to design and fly a number of complex aircraft of varying sizes, shapes and applications.&lt;/li&gt;&#xA;&lt;li&gt;Complete enough to extract power using it.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On a basic level, lift is the force generated as solid body 'turns' fluid while satisfying the conservation laws. The issue is not that we don't know &lt;em&gt;what&lt;/em&gt; lift is, but there is no consensus about &lt;em&gt;how&lt;/em&gt; to explain it. Most of the 'theories' of lift are just models try to explain the same thing based on the points of view of the people involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way the pilot views the lift is different from that of an engineer or a mathematician. For the pilot, the lift is a force that keeps the aircraft in the air (and proportional to $\rho V^{2} S$ and angle of attack, at-least till stall), while a mathematician can say that lift 'follows naturally' by solving Navier-Stokes Equation (whether it can realistically solved or not is another matter) for some conditions. Of course, this is of no practical use to either the engineer or the pilot. Both can claim (rightfully) that they are correct, while a physicist can object that NS assumes that the fluid is a continuum, while it is not the case in realty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason for so many theories of lift. As the fluid flow is extremely complex, some simplification is done in each theory (like omitting viscosity in the Euler or potential flow theory). Based on the simplification, the theory is either useful in some (or most) of the situations or is outright wrong.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Which bits are still in dispute, and which bits are fully accepted?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Almost all 'theories' of lift accept that lift is a force and its requirements. As far as engineering goes, the issue is which bits of are necessary for the problem in hand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the potential flow theory can predict the lift as long as we are not approaching stall. After that all bets are off. There is no point in arguing about a result from a theory after using it in a situation for which it was not designed for in the first place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason for arguments about lift. Some theories are developed to describe a particular situation (for example inviscid flow) and then applied in general, which obviously leads to confusion and dispute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as engineering is considered we have enough understanding of lift to create the flying machines we need though not as much as to explain everything that happens with accuracy.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-06T15:32:48.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21675" PostTypeId="2" ParentId="1486" CreationDate="2015-10-06T16:33:58.407" Score="14" Body="&lt;p&gt;I ejected from an FJ-4 at 17,000 ft at 410 kts IAS. I was very briefly unconscious.&#xA;When I woke up I was head down and looking up between my legs at an object drifting away from me which I saw as my parachute back pack. I could see the tabs down each side side of the pack as well as the pin attached to the D ring. I fell  about 13,000 feet before I looked at the D ring. I occurred to me that I might as well pull it even though I still thought I had somehow lost my chute. I felt a minor shock and looked up to see my parachute open. Then it dawned on me that the object I thought was my back pack was the ejection seat. As I remember separating from the seat was simply a matter of the pilots body and the ejection seat having differing response to the wind experienced after ejecting.This incident took place in July of 1957. My back will probably quit hurting before many more years.&lt;/p&gt;&#xA;" OwnerUserId="11619" LastActivityDate="2015-10-06T16:33:58.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21676" PostTypeId="2" ParentId="21671" CreationDate="2015-10-06T18:19:26.167" Score="2" Body="&lt;p&gt;Peter Kämpf would be the one to answer this definitively, but in the context of his full answer it's clear that he is referring to the function of the vertical stabiliser during sideslip. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft is slipping the flow will have some component perpendicular to the vertical tail fin, and thus the fin will have some angle of attack. Sideslip too steeply and the fin will stall, just like any other aerofoil.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-06T18:19:26.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21677" PostTypeId="1" CreationDate="2015-10-06T18:38:43.710" Score="1" ViewCount="67" Body="&lt;p&gt;In both the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow&quot;&gt;Tenerife accident&lt;/a&gt; in 1977 and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Florida_Flight_90&quot; rel=&quot;nofollow&quot;&gt;Air Florida accident&lt;/a&gt; in 1982, the first officer (FO) in the cockpit opposed the decision of the captain to take off. What should the FO do if the captain is determined to do the wrong - possibly even the fatal - thing? &lt;/p&gt;&#xA;" OwnerUserId="11620" LastEditorUserId="62" LastEditDate="2015-10-06T18:43:42.273" LastActivityDate="2015-10-06T18:43:42.273" Title="How is control of the airplane passed from one pilot to another?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;pilots&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="1" ClosedDate="2015-10-06T19:44:41.647" ContentLicense="CC BY-SA 3.0" />
  <row Id="21679" PostTypeId="1" CreationDate="2015-10-06T18:56:29.507" Score="5" ViewCount="14437" Body="&lt;p&gt;If the control system in an Airbus is fly-by-wire, then what is the control system in Boeings? How does it work? What are its general differences from the fly-by-wire?&lt;/p&gt;&#xA;" OwnerUserId="11620" LastEditorUserId="62" LastEditDate="2015-10-06T19:34:27.030" LastActivityDate="2015-10-07T03:41:08.057" Title="Airbus is to fly-by-wire as Boeing is to...?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-systems&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ClosedDate="2015-10-07T07:24:44.927" ContentLicense="CC BY-SA 3.0" />
  <row Id="21680" PostTypeId="1" AcceptedAnswerId="21730" CreationDate="2015-10-06T19:09:16.563" Score="4" ViewCount="1092" Body="&lt;p&gt;&quot;White-tail airliners&quot; refers to either airliners without any customer order (like the beginning of A300 production), or those where the order was cancelled after/during production and where no new purchaser has been found (like the &lt;a href=&quot;http://www.bloomberg.com/news/articles/2015-01-28/skymark-said-to-file-for-bankruptcy-after-airbus-a380-deal-flops&quot; rel=&quot;nofollow&quot;&gt;Skymark A380 deal&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do the manufacturers handle the white-tail airliners?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-10-09T10:03:01.513" LastActivityDate="2017-01-14T23:42:17.527" Title="What do airliner manufacturers do with aircraft for which have no buyers?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;economics&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21681" PostTypeId="2" ParentId="21679" CreationDate="2015-10-06T20:07:16.440" Score="5" Body="&lt;p&gt;Boeing uses a more direct approach to control (but both systems have warnings). In short it boils down to who has final authority of control surface actuation. Fly by wire does not just mean that control surfaces are controlled electronically (even the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;Cessna 172&lt;/a&gt; has electric flaps) but that a computer in some way takes the pilot (or pilots) inputs and generates a control surface output. In the airbus case the computer has the final say, so if the pilot commands the plane to do something it should not, the computer will not move the control surfaces and allow it to enter such an attitude or speed. Boeing takes the reverse view and gives the pilot final authority so what ever control inputs are made translate to control surface movements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in mind Boeing does have things like a yoke shaker in the event of approaching a stall and a yaw damper etc. Airbus will allow full control surface actuation with &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_modes&quot; rel=&quot;nofollow&quot;&gt;Direct Law&lt;/a&gt; however the plane is not normally in this mode. Boeings &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_modes#cite_note-Boeing_B-777:_Fly-By-Wire_Flight_Controls-8&quot; rel=&quot;nofollow&quot;&gt;Standard protections and augmentations&lt;/a&gt; is similar but will allow the pilot to enter the conditions &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;...to inform the pilot that the command being given would put the&#xA;  aircraft outside of its normal operating envelope, but the ability to&#xA;  do so is not precluded.&quot;&#xA;  (&lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the contrary vertical stick motion in an airbus in flight actually controls load factor and not necessarily pitch directly. So its always some form of proportion to the aircrafts speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If memory serves Boeing control surfaces are set up such that movement of one yoke will move the other yoke in tandem, likewise they can not be simultaneously moved in opposite directions while airbus controls can be moved in opposite direction and the computer will summate the inputs (although an override button is present on each stick to disconnect the others should something be improperly acting on it).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-07T03:27:48.483" LastActivityDate="2015-10-07T03:27:48.483" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21682" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T21:31:17.257" Score="-5" Body="&lt;p&gt;The principles of aerodynamics and fluid dynamics are what you would call &quot;well understood.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ambiguity is around what so-called &quot;lift&quot; is, which can be a nebulous concept. For example, if you drop a piece of paper it will drift slowly to the ground, essentially a form of gliding; this same air resistance is the basic force keeping a plane aloft. Would you consider this &quot;lift&quot;? Once you get into these arguments about semantics, things get vague.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just as one example of the craziness, the FAA test, the same one you are taking, requires you to know the &quot;four forces of flight&quot; in which the so-called &quot;lift&quot; is the force that keeps the aircraft aloft. The only problem is that &lt;em&gt;you can compute lift&lt;/em&gt; by equations that are in every book on aerodynamics and if you actually do this (like I did) you will find that the force generated is nowhere near enough to keep a plane in the sky. If &quot;lift&quot; were the force keeping a plane up, it would fall like a rock, so the FAA guidelines are simply completely wrong. It's just a huge semantic hairball that is not going to go away anytime soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The worst part of it is that EVERY pilot (or wannabe pilot) I have ever known thinks they know exactly what &quot;lift&quot; is and, even worse, their beliefs generally fall into one of 5 or 6 different categories with contradictory principles. This leads to huge arguments whenever the subject comes up. After 15 years of this, I just try to stay out of it, other than to tell the beginners not to make the same mistake (like I am telling you now).&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-07T02:52:31.680" LastActivityDate="2015-10-07T02:52:31.680" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21683" PostTypeId="1" AcceptedAnswerId="21700" CreationDate="2015-10-06T21:53:15.363" Score="15" ViewCount="6133" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Republic_XF-84H&quot;&gt;Republic XF-84H&lt;/a&gt;, known as the &quot;Thunderscreech&quot; was an experimental version of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Republic_F-84F_Thunderstreak&quot;&gt;F-84F Thunderstreak&lt;/a&gt;. It was intended to be a supersonic turboprop fighter.  Even at idle, the prop tips rotated at supersonic speeds and the plane is often claimed to be the loudest ever built, supposedly audible 25 miles away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most sources describe a continuous sonic boom due to the supersonic prop tips. However, a &lt;a href=&quot;https://www.google.co.uk/search?q=thunderscreech+900+sonic+booms+per+minute&quot;&gt;fairly common claim on the internet&lt;/a&gt; is that they caused &quot;900 sonic booms per minute.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there any truth to the claim that the plane caused 900 sonic booms per minute?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One's first thought should be, &quot;no&quot;: because the prop tips are continuously above the speed of sound, they emit a continuous sonic boom (as most sources claim), not 900 separate ones per minute.  However, since the prop tips were supersonic and the roots were not, it follows that a section of the prop's length would be in the transonic range. Any change to the wind or propeller RPM would cause more or less of the propeller to be moving supersonically.  I suppose that, say, an appropriate oscillation in the turbine engine could cause the continuous boom to be modulated by some 15Hz (900-per-minute) component.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2019-02-28T02:42:14.387" Title="Did the XF-84H Thunderscreech really cause &quot;900 sonic booms per minute&quot;?" Tags="&lt;military&gt;&lt;supersonic&gt;&lt;turboprop&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21684" PostTypeId="2" ParentId="3070" CreationDate="2015-10-06T22:04:51.003" Score="10" Body="&lt;p&gt;Airbus recently filed a patent for a two-level seating that looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4PjKa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4PjKa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mH4zk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mH4zk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Both of these images came from Airbus and the European Patent Office)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this is just a patent application there's no indication how this might be certified, or whether it will enter production at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not clear to me whether this is a way to pack in more passengers, or a way to persuade them to pay a premium fare for more room.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One patent application relating to this is &lt;a href=&quot;http://worldwide.espacenet.com/publicationDetails/biblio?DB=worldwide.espacenet.com&amp;amp;II=0&amp;amp;ND=3&amp;amp;adjacent=true&amp;amp;locale=en_EP&amp;amp;FT=D&amp;amp;date=20151001&amp;amp;CC=US&amp;amp;NR=2015274298A1&amp;amp;KC=A1&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; - there may be others.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-06T22:04:51.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21685" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T22:04:55.753" Score="35" Body="&lt;p&gt;&lt;strong&gt;Short answer:&lt;/strong&gt; Yes, our understanding of lift is complete, but solving the equations for some practical cases needs more resources than what is technically sensible.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Lift is a matter of definition&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First of all, lift is only one part of the aerodynamic forces. It is the component normal to the direction of airflow. Since the aircraft will distort the local flow around itself, this direction is taken ideally at an infinite distance where the air is undisturbed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other component is, of course, drag. It is defined as the part of the aerodynamic forces parallel to the direction of airflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic forces are the sum of all local pressures, which act orthogonally on the local surface of the airplane, and the shear forces, which act parallel to the local surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aerodynamics was researched first, electric fields were new and exciting, and the same equations which help to calculate electromagnetic forces could be used to calculate aerodynamic forces. Therefore, abstract concepts like &lt;a href=&quot;https://en.wikipedia.org/wiki/Potential_flow&quot; rel=&quot;noreferrer&quot;&gt;sources or sinks&lt;/a&gt; were used to explain aerodynamics. This made it not easier to understand, and many authors tried to find simpler explanations. Unfortunately, they were mostly too simple and not correct, but the next generation of authors would mostly copy what had been written before, so the wrong concepts were still bandied about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get to the bottom of it, it might help to look at lift at a molecular level:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every air molecule is in a dynamic equilibrium between inertial, pressure and viscous effects:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Inertial means that the mass of the particle wants to travel on as before and needs force to be convinced otherwise.&lt;/li&gt;&#xA;&lt;li&gt;Pressure means that air particles oscillate all the time and bounce into other air particles. The more bouncing, the more force they exert on their surroundings.&lt;/li&gt;&#xA;&lt;li&gt;Viscosity means that air molecules, because of this oscillation, tend to assume the speed and direction of their neighbors.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All three contributions are well understood, and with the Navier-Stokes equations they can be completely mathematically expressed. What is still improving is our ability to solve these equations, and in turbulent flow the characteristic length required to capture all effects is so small that it is practically impossible to solve those equations fully with finite time and resources.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flow over the upper side of the wing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now to the airflow: When a wing approaches at subsonic speed, the low pressure area over its upper surface will suck in air ahead of it. See it this way: Above and downstream of a packet of air we have less bouncing of molecules (= less pressure), and now the undiminished bouncing of the air below and upstream of that packet will push its air molecules upwards and towards that wing. The packet of air will rise and accelerate towards the wing and be sucked into that low pressure area. Due to the acceleration, the packet will be stretched lengthwise and its pressure drops in sync with it picking up speed. Spreading happens in flow direction - the packet is distorted and stretched lengthwise, but contracts in the direction orthogonally to the flow. Once there, it will &quot;see&quot; that the wing below it curves away from its path of travel, and if that path would remain unchanged, a vacuum between the wing and our packet of air would form. Reluctantly (because it has mass and, therefore, inertia), the packet will change course and follow the wing's contour. This requires even lower pressure, to make the molecules overcome their inertia and change direction. This fast-flowing, low-pressure air will in turn suck in new air ahead and below of it, will go on to decelerate and regain its old pressure over the rear half of the wing, and will flow off with its new flow direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that lift can only happen if the upper contour of the wing will slope downwards and away from the initial path of the air flowing around the wing's leading edge. This could either be camber or angle of attack - both will have the same effect. Since camber allows for a gradual change of the contour, it is more efficient than angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flow over the lower side of the wing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A packet of air which ends up below the wing will experience less uplift and acceleration, and in the convex part of highly cambered airfoils it will experience a compression. It also has to change its flow path, because the cambered and/or inclined wing will push the air below it downwards, creating more pressure and more bouncing from above for our packet below the wing. When both packets arrive at the trailing edge, they will have picked up some downward speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/V7Ujo.png&quot; alt=&quot;Airfoil in wind tunnel with smoke trails indicating flow&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Behind the wing, both packets will continue along their downward path for a while due to inertia and push other air below them down and sideways. Above them, this air, having been pushed sideways before, will now fill the space above our two packets. Macroscopically, this looks like two big vortices. But the air in these vortices cannot act on the wing anymore, so it will not affect drag or lift. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;here for more on that effect&lt;/a&gt;, including pretty pictures.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Lift can be explained in several, equivalent ways&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Following the picture of a pressure field outlined above, lift is the difference of pressure between upper and lower surface of the wing. The molecules will bounce against the wing skin more at the lower side than at the upper side, and the difference is lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or you look at the macroscopic picture: A certain mass of air has been accelerated downwards by the wing, and this required a force to act on that air. This force is what keeps the aircraft up in the air: Lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the wing as a black box and only pay attention to the impulse of the inflowing and outflowing air, the wing will change the impulse by adding a downward component. The reaction force of this impulse change is lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, you will arrive at the same result. By the way: Most of the directional change happens in the forward part of the airfoil, not at the trailing edge!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/AGhZF.png&quot; alt=&quot;streamlines around a wing and direction of impulses&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Supersonic flow&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When the aircraft moves faster than pressure changes propagate through air, the changes in pressure are no longer smooth, but sudden. The aircraft will push the air molecules aside, producing a compression shock. Behind the shock front pressure, temperature and density are higher than ahead of it, and the increase is proportional to the local change in flow direction. The incremental pressure change $\delta p$ due to the aircraft hitting air with an incremental angle of $\delta\vartheta$, expressed in terms of the undisturbed flow with the index $\infty$, is proportional to the change in the streamlines:&#xA;$$\delta p = -\frac{\rho_{\infty}\cdot v^2_{\infty}}{\sqrt{Ma^2_{\infty} - 1}}\cdot\delta\vartheta$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Pressure&quot; rel=&quot;noreferrer&quot;&gt;Gas pressure on a molecular level is the number and severity of particle collisions&lt;/a&gt;. The air molecules experience more collisions on the downstream side of the shock, since air pressure is higher there. The average  direction of the additional collisions is indeed orthogonal to the shock, because it is the boundary between blissfully unaware molecules at ambient pressure ahead of the shock and their bruised brethren downstream which have just crossed that boundary. Once a molecule has passed the shock, the collisions are coming again equally from all sides and its speed does not change any more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the surface curves away from the local flow direction, the air produces an &lt;a href=&quot;https://en.wikipedia.org/wiki/Prandtl%E2%80%93Meyer_expansion_fan&quot; rel=&quot;noreferrer&quot;&gt;expansion fan&lt;/a&gt; which re-sets the old pressure and density values when the air flows again in its original direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pure supersonic lift is only a matter of the angle of incidence, and any local curvature of the wing will not change overall lift (but increase drag). Now the total aerodynamic force is normal to the wing, and drag will become proportional to the angle of incidence. In hypersonic flow you will get good results with the venerable impact theory first formulated by Isaac Newton.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Separated flow&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This happens when the air molecules are &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;no longer able to follow the contour of the aircraft&lt;/a&gt;. Instead, you get a chaotic, oscillating flow pattern which is very hard to compute exactly. This is really the only part of aerodynamics which cannot be predicted precisely, even though the effects are well understood. Separated flow will produce lift, too, but less than attached flow. In delta wings, this separation is produced on purpose to create what is called &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift/21071?s=1%7C0.4663#21071&quot;&gt;vortex lift&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-10-07T05:40:20.923" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="21686" PostTypeId="2" ParentId="21664" CreationDate="2015-10-06T22:15:26.193" Score="4" Body="&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt;: we can very precisely model aerodynamic forces at the micro level; we can reasonably predict behavior at the macro level by aggregating micro-level models (CFD). We don't have a universally-applicable story for &lt;em&gt;why&lt;/em&gt; the macro level behavior is what it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuller explanation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the risk of being a bit pedantic, I'm going to back up a couple of steps of abstraction in order to provide a more-complete picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The overall aerodynamic force on a body is decomposed into vectors normal to the direction of travel and parallel to the direction of travel, which are labeled 'lift' and 'drag' respectively; they are not distinct forces in &amp;amp; of themselves. Aerodynamic force itself is often decomposed at a different scale into pressure &amp;amp; friction; for the most part, friction only contributes to the 'drag' component while pressure contributes to both the 'lift' &amp;amp; 'drag' components.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trying to tell a stylized story about why the integrated pressure &amp;amp; friction across the entire body result in a particular net force is challenging at best, since it is affected by the idiosyncrasies of each body; various models (such as Venturi, downwash, &amp;amp; circulation) really just provide designers &amp;amp; analysts with rough rules of thumb within particular flight regimes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This last point is more important than it appears. As soon as you enter transonic flight (a mix of subsonic &amp;amp; supersonic flow at the surface of the body), drag increases precipitously (standing shocks creating adverse pressure gradients). Passing through to fully-supersonic flight you find yet another set of behaviors (because the leading shock radically alters the pressure distribution on the body). Don't even get me started on hypersonic flow (where the temperature change across the shocks is enough to decompose the N2 &amp;amp; O2 from the air itself).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt; Peter Kampf's answer covered most of the same topics as mine, with pictures, so I'll just add this for completeness: &lt;a href=&quot;https://i.stack.imgur.com/NYg6k.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NYg6k.jpg&quot; alt=&quot;diagram of supersonic lift &amp;amp; drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="169" LastEditorUserId="169" LastEditDate="2015-10-06T22:20:54.090" LastActivityDate="2015-10-06T22:20:54.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21687" PostTypeId="2" ParentId="21683" CreationDate="2015-10-06T22:40:16.030" Score="6" Body="&lt;p&gt;No, because that isn't how it works&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A plane doesn't 'make' sonic booms, a sonic boom is the result of an aircraft overtaking the sound it is making, meaning that you're hearing the aircraft now, and several seconds ago, all at once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not an actual object, more a kind of fictional line of where the sound has reached. Any aircraft therefore produces one constant sonic boom, or infinite individual sonic booms, depending on your perspective &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 900 per minute is just internet silliness. As opposed to Internet seriousness, which is to be avoided at all costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now in theory as you say, props passing the sound barrier could make lots of individual sound points, IE you hear the blades pass multiple times as they move towards and away from you vertically (around the propellor hub) - this would be significantly higher than 900 per minute, I'd have thought. So from that perspective you could hear the propellor create a staccato of boom-silence-boom.... But it wouldn't be as loud as the plane itself, and would only be heard as part of the plane passing. The propellor are still moving with the plane, remember.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-10-06T22:40:16.030" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21688" PostTypeId="1" AcceptedAnswerId="21901" CreationDate="2015-10-06T22:42:12.337" Score="26" ViewCount="2419" Body="&lt;p&gt;Every time I deplane a Virgin America A320, I notice that they grab something from the jet bridge, and stuff it between the jump seats. I haven't seen any other commercial airlines with things like this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XUG1O.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XUG1O.jpg&quot; alt=&quot;item in square&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="14897" LastEditDate="2017-07-29T00:47:13.620" LastActivityDate="2020-03-06T11:58:17.777" Title="What is this device they bring on board from the jet bridge when we park?" Tags="&lt;commercial-aviation&gt;&lt;ground-operations&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21689" PostTypeId="2" ParentId="21679" CreationDate="2015-10-06T22:47:27.963" Score="1" Body="&lt;p&gt;Boeing is to fly by wire as Airbus is to fly by computer, would probably be closer to the mark.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both are fly by wire, but Boeing is closer to direct input - I move the yoke halfway to the limit, the controls move halfway to their limit&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While Airbus is a suggestion to the aircraft as to what you'd like it to do - I move the side stick halfway to the limit, and the plane performs that action at something like half the rate the performance envelope should allow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sort of.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-10-06T22:47:27.963" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21690" PostTypeId="1" CreationDate="2015-10-06T23:00:33.183" Score="6" ViewCount="20377" Body="&lt;p&gt;What exactly does the term &quot;fly-by-wire&quot; mean? Where did it originate? I understand that it refers to control systems. If an aircraft is not fly-by-wire, what is it? That is, what are the alternatives?&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2019-11-25T21:10:41.360" Title="What is fly-by-wire?" Tags="&lt;flight-controls&gt;&lt;terminology&gt;&lt;fly-by-wire&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21691" PostTypeId="2" ParentId="21690" CreationDate="2015-10-06T23:09:22.010" Score="6" Body="&lt;p&gt;Fly-by-wire means that the control commands travel by wire to the control surfaces. There, either electric motors or hydraulic actuators do the physical work of moving the surfaces. The pilot has either a conventional control column or a side stick with transducers which will encode the commands of the pilot into electric signals. Optionally, a computer can be employed to modify the signals such that overload conditions or dangerous maneuvers are avoided.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other control systems can be summed up as mechanical: Some pushrod or steel cable runs all the length to the control surface. To relief the pilot of the mechanical work, those pushrods can be boosted by hydraulics, so the mechanical movement of the control column or stick will become a command for the hydraulic actuator, similar to the electric signals in a fly-by-wire system. Early systems used a variety of &lt;a href=&quot;https://aviation.stackexchange.com/questions/15673/what-is-the-working-principle-of-trim-tabs-on-the-elevators/15674#15674&quot;&gt;aerodynamic means&lt;/a&gt; to lighten control forces, and small aircraft have low enough control forces that they can be flown with a direct, unboosted mechanical linkage. In some cases, it is even necessary to artificially increase control forces to give the pilot enough feedback.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Russian combat aircraft prefer to use pairs of steel cables over pushrods because they will be more resilient when hit by a bullet. Also, most early aircraft used cables for weight reasons. Today, pushrods are preferred because they allow a stiffer linkage and less friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the history of fly-by-wire, I could just copy the Wikipedia entry, but I prefer to &lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire#History&quot; rel=&quot;nofollow noreferrer&quot;&gt;link to it here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-06T23:15:23.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21692" PostTypeId="2" ParentId="21690" CreationDate="2015-10-06T23:10:48.223" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Fly-by-wire (FBW)&lt;/strong&gt; is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires (hence the fly-by-wire term), and flight control computers determine how to move the actuators at each control surface to provide the ordered response. The fly-by-wire system also allows automatic signals sent by the aircraft's computers to perform functions without the pilot's input, as in systems that automatically help stabilize the aircraft, or prevent unsafe operation of the aircraft outside of its performance envelope.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Light aircraft use a direct mechanical linkage using cables and/or push rods. Larger aircraft, and aircraft manufactured before the introduction of FBW use hydraulic actuators slaved directly to the controls in the cockpit.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorUserId="39" LastEditDate="2015-10-07T03:45:37.463" LastActivityDate="2015-10-07T03:45:37.463" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21693" PostTypeId="2" ParentId="21690" CreationDate="2015-10-06T23:12:27.627" Score="3" Body="&lt;p&gt;The irony is that airplanes that are not fly-by-wire are fly by wires... Steel cables that is. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Earlier planes (and many smaller GA planes to this day) typically use steel control cables that directly connect the control surfaces to the joke or stick. Such as can be seen running to the tail section of this plane &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vONPS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vONPS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://eaa670.wordpress.com/page/2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not limited to small planes by any means, many larger planes use control cables as well. You can also use control rods which is common place on Mooney aircraft however those generally come at the cost of weight but may provide a more tactile feel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dHrR1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dHrR1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fly-By-Wire&lt;/a&gt; generally means that the control inputs are translated via electronic cables to a set of hydraulic actuators to move the control surface. To expand on that, FBW systems also decide &lt;em&gt;what&lt;/em&gt; movements the control surfaces will make and often do not allow the surfaces to move such that it will put the plane in a dangerous attitude. Simple electric signal control of actuators is not necessarily FBW and even planes as simple as the Cessna 172 have electronically controlled flaps that are not considered FBW.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2019-11-25T21:10:41.360" LastActivityDate="2019-11-25T21:10:41.360" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21694" PostTypeId="2" ParentId="21690" CreationDate="2015-10-06T23:40:51.200" Score="9" Body="&lt;p&gt;The fly-by-wire means that in the aircraft, the (pilot or autopilot) control inputs are fed to the (flight) computer, which processes them and determines the required control surface movements and transmits this by electrical signals (through wires, hence the term fly-by-wire) to the appropriate actuators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is in contrast with the mechanical system, where the pilot control inputs are directly transmitted to the flight control actuators, through push-pull rods or cables. The following figure shows the schematic of a mechanical and fly-by-wire system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J51vL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J51vL.jpg&quot; alt=&quot;Fly-by wire&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: euroaviasevilla.es&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first aircraft to use this mode of control was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Avro_Canada_CF-105_Arrow&quot; rel=&quot;noreferrer&quot;&gt;Avro Arrow&lt;/a&gt;, which used a dual-channel fly-by-wire system made of analog circuits. The flight control mechanism on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Apollo_Lunar_Module&quot; rel=&quot;noreferrer&quot;&gt;Apollo Lunar Module&lt;/a&gt; was fly-by-wire, the Primary Guidance, Navigation, and Control System, which was referred to as PGNCS, pronounced 'pings'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, NASA tested the fly-by-wire system in a F-8 aircraft, a schematic of which is shown below. Note that it uses Apollo flight computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oBXFc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oBXFc.png&quot; alt=&quot;F8 Fly-by-wire&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Computers Take Flight- A history of NASA's Pioneering Fly-by-wire Project&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In civil aviation Concorde and A320 (which had a digital-fly-by-wire system) introduced fly-by-wire systems, while in military, it was the F-16. At present, almost all combat aircraft and large airliners use fly-by-wire systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an extension, the system is called fly-by-light (or fly-by-optics) is the signals are transmitted through optical cables. If the wires are eliminated altogether, it is called &lt;a href=&quot;https://www.newscientist.com/article/dn9176-fly-by-wireless-plane-takes-to-the-air/&quot; rel=&quot;noreferrer&quot;&gt;fly-by-wireless&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-06T23:55:22.290" LastActivityDate="2015-10-06T23:55:22.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21695" PostTypeId="1" AcceptedAnswerId="21697" CreationDate="2015-10-07T02:43:52.187" Score="2" ViewCount="306" Body="&lt;p&gt;I was recently flying my rc helicopter and I would sometimes turn it around and move it forward and sometimes I lost control of the helicopter while doing that a few times and crashed it everywhere (accidently crashed it into my poor cat). Every time I fly this helicopter it randomly starts turning to the left uncontrollably. Also I have had where I kept the thrust at the same level and then I would fly it into a different room and it would start raising in altitude uncontrollably. So can a helicopter or aircraft fly into its own wake and was it the wake of the helicopter that caused these problems with my helicopter?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="13197" LastEditDate="2016-02-14T02:28:13.803" LastActivityDate="2016-02-14T02:28:13.803" Title="Can an aircraft or helicopter run into its own wake vortex?" Tags="&lt;aircraft-performance&gt;&lt;helicopter&gt;&lt;wing-tip-vortex&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21696" PostTypeId="1" AcceptedAnswerId="21701" CreationDate="2015-10-07T02:54:04.103" Score="9" ViewCount="356" Body="&lt;p&gt;In some technology areas, there are &quot;standard&quot; texts - for GA type aircraft design, I think of Stinton's &quot;Design of the Airplane&quot;. For radar, Skolnik's &quot;Radar Handbook&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an equivalent text for parachute / para-airfoil design?&lt;/p&gt;&#xA;" OwnerUserId="9927" LastEditorUserId="19" LastEditDate="2016-11-23T13:02:58.013" LastActivityDate="2016-11-23T13:02:58.013" Title="Is there a standard text for parachute design?" Tags="&lt;parachute&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21697" PostTypeId="2" ParentId="21695" CreationDate="2015-10-07T03:15:14.430" Score="6" Body="&lt;p&gt;Helicopters are not easy to fly - whether full-scale manned aircraft or RC models. I would bet that your issues are more related to pilot error than any fault of the machine (other than the fact that it is a helicopter, and inherently unstable).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, almost any aircraft can be maneuvered in such a way as to encounter its own wake, and the helicopter is no exception. In fact it's much easier do to this in a helicopter than in a fixed-wing aircraft: A condition known as &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_ring_state&quot;&gt;&quot;settling with power&quot;&lt;/a&gt; (or &quot;vortex ring state&quot;) can occur when a helicopter descends into its own rotor wash, e.g. by descending directly vertically in calm air. The results of such an encounter can be &quot;unpleasant&quot; - a number of helicopter accidents have been attributed to this sort of encounter.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-07T03:15:14.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21698" PostTypeId="2" ParentId="21679" CreationDate="2015-10-07T03:41:08.057" Score="4" Body="&lt;p&gt;Using a pure definition of &lt;em&gt;fly-by-wire&lt;/em&gt;, &lt;strong&gt;both Boeing and Airbus airliners can be considered &lt;em&gt;fly-by-wire&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;tl;dr:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing has built some FBW airliners (777, 787) and some that aren't (707/720, 737, 747, 757, 767).&lt;/li&gt;&#xA;&lt;li&gt;Airbus has built some FBW airliners (A320 series, A330, A340, A350, A380) and some that aren't (A300, A310).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;long version:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires [...], and flight control computers determine how to move the actuators at each control surface to provide the ordered response.&lt;br&gt;&#xA;  &lt;sub&gt;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;nofollow&quot;&gt;Fly-by-wire, Wikipedia&lt;/a&gt;&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;With that description in mind, both manufacturers build FBW aircraft. Pilots' control inputs are translated into aircraft flight control surface movements by a set of redundant computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing's first FBW airliner was 1994's &lt;strong&gt;777&lt;/strong&gt;, and their only other pure-FBW design is the &lt;strong&gt;787&lt;/strong&gt;. The 748 is a partial-FBW design. Both the 777 and 787 have some computer-enforced limits in place to keep the aircraft within the flight envelope, but those limits can be overridden, and the aircraft generally are said to 'feel like a normal airplane'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus's first FBW airliner was the 1987's &lt;strong&gt;A320&lt;/strong&gt;, and all their subsequent designs are FBW. &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_modes#Normal_law&quot; rel=&quot;nofollow&quot;&gt;Airbus's control logic is much less direct than Boeing's&lt;/a&gt;, containing full flight envelope protection in the 'Normal Law' configuration, and correspondingly less protection if the aircraft reverts to 'Alternate Law' mode (which is roughly comparable to Boeing FBW). None is provided in what is called 'Direct Law', where the computers simply pass commands directly to the flight control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, &lt;strong&gt;both manufacturers build fly-by-wire airliners&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2015-10-07T03:41:08.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21699" PostTypeId="2" ParentId="21664" CreationDate="2015-10-07T03:55:03.437" Score="5" Body="&lt;p&gt;Scientifically speaking, lift is perfectly understood. Lift is merely the vertical component of force generated by a body moving through a fluid. And we know perfectly well how to calculate forces on a body moving through a fluid since the Navier-Stokes equations was published in 1822. That is to say, we know the physics of it and it has to do with the viscosity of fluids (in the case of aircraft, air).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But using the Navier-Stokes equations to design a wing is like trying to use &lt;a href=&quot;https://en.wikipedia.org/wiki/Quantum_electrodynamics&quot; rel=&quot;noreferrer&quot;&gt;Quantum-Electrodynamics (QED)&lt;/a&gt; to cook the perfect steak. Since gravity isn't involved in the perfectionness of steak, all you need to formulate a perfect steak is QED.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Navier-Stokes equations calculate forces on a single point on the wing. Therefore you have to repeat the calculations over the whole wing to calculate lift. Over the last 190+ years mathematicians and engineers have formulated simpler algorithms to calculate the result of the Navier-Stokes equations and over the last 30 or so years we've used computers to calculate lift. However, you can see how this doesn't tell you the ideal shape to generate the aerodynamic characteristics you want. You can also see how this doesn't explain &quot;lift&quot; in terms a human can understand. It's all just large arrays of numbers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to explain lift in terms a human can understand? Maybe. We've certainly given names to how certain shapes generate certain output when subjected to the Navier-Stokes equations. Names such as &quot;Coanda effect&quot; and &quot;Bernoulli Principle&quot; etc. In the end, nature/physics doesn't care what name we give to our interpretation of the result of the Navier-Stokes equations - if calculating the equations result in a vertical force vector upwards you have lift. Maybe, like quantum physics, we'll never get a complete intuitive understanding of what lift is. But we certainly have the complete theory to explain it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Additional note: Apart from not being helpful in helping us formulate a theory of wing design, the Navier-Stokes equations are also problematic because it's computationally expensive. For example, it's often not practical to use the Navier-Stokes equations to simulate turbulence (even though it's possible in theory). So we often take shortcuts for certain forms of simulations using other simpler but less perfect equations.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-10-07T03:55:03.437" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21700" PostTypeId="2" ParentId="21683" CreationDate="2015-10-07T05:17:25.640" Score="22" Body="&lt;p&gt;I think it is a matter of where you stand (literally).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the front or the rear the shock waves from the propeller tips would hit your ears continuously, and the result would be constant noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When standing laterally, the propeller tips would move towards and away from you and produce a variation of noise intensity of the frequency produced by the product of propeller RPM and blade count.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that the &lt;a href=&quot;https://web.archive.org/web/20160928082751/http://www.enginehistory.org/Allison/XF-84Propulsion.html&quot; rel=&quot;noreferrer&quot;&gt;design RPM of the XF-84H propeller&lt;/a&gt; was 3000, and since the propeller had three blades, the frequency should have been 9000 per minute, not 900. The airframe could be split ahead of the cockpit to allow the installation of several nose sections with their own gearbox and propeller. Several gearboxes and propellers were prepared with propeller design speeds between 2100 RPM and 3000 RPM, but the test program was ended prematurely, so most of the planned variations were never flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only judge from the little information available online and count myself lucky not to have witnessed a power-up of the XF-84H (for me personally, the loudest aircraft is still a &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-17&quot; rel=&quot;noreferrer&quot;&gt;Sukhoi 22M-4&lt;/a&gt; &amp;ndash; you think &quot;man, this afterburner is loud!&quot; and only then the pilot switches the afterburner on), and it seems that the 900 per minute figure must have lost a zero on its way of becoming an internet meme.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that I only speak of a variation of noise &amp;ndash; as Jon Story writes, a sonic boom is what arrives at your ear, not what is produced by the propeller.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-07-02T18:34:53.363" LastActivityDate="2018-07-02T18:34:53.363" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="21701" PostTypeId="2" ParentId="21696" CreationDate="2015-10-07T05:28:31.203" Score="8" Body="&lt;p&gt;Some useful texts are &lt;a href=&quot;http://ftp.rta.nato.int/public//PubFullText/AGARD/AG/AGARD-AG-295///AGARDAG295.pdf&quot;&gt;The Aerodynamics of Parachutes&lt;/a&gt; by Cockrell, &lt;a href=&quot;https://info.aiaa.org/tac/AASG/ADSTC/RamAir%20Parachute%20Design/Forms/AllItems.aspx&quot;&gt;Ram Air Parachute Design&lt;/a&gt; by Lingard, and the Parachute Recovery Systems Design Manual by Knacke.  The Lingard and Cockrell papers both have extensive references that are worth pursuing.  The Knacke manual is, as far as I know, only available in hardcopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that the designers of modern sport ram-air parachutes and paragliders are more concerned with protecting trade secrets than they are in publishing research.  The paragliding side of the aisle is a bit more willing to share.  There is an online &lt;a href=&quot;http://laboratoridenvol.com/paragliderdesign/index.html&quot;&gt;paraglider design handbook&lt;/a&gt;, and there are several open source paraglider CAD software packages available.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2015-10-07T05:28:31.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21702" PostTypeId="1" CreationDate="2015-10-07T05:51:47.757" Score="2" ViewCount="75" Body="&lt;p&gt;Why don't airplane include a satellite technology to upload the critical (Voice/Engine etc) data recorded in FDR to satellite. This would be very useful, in case of missing FDR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any technology/Equipment existing on this issue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: FDR can just to start transmitting the very latest data first followed by old data in sequence before aircraft gets into crashing mode. Probably we do have some specification/limits to determine the aircraft crashing probabilities. Even if FDR is missing from the crash site we will have some limited data(might not be complete data) which got stored after crash trigger.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="9966" LastEditDate="2015-10-07T06:20:19.933" LastActivityDate="2015-10-07T06:20:19.933" Title="Why Black Boxes are not capable of transmitting its Critical Data directly to satellite?" Tags="&lt;radio-communications&gt;&lt;flight-data-recorder&gt;&lt;datasets&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-10-07T07:12:05.220" ContentLicense="CC BY-SA 3.0" />
  <row Id="21703" PostTypeId="1" AcceptedAnswerId="21710" CreationDate="2015-10-07T07:06:50.187" Score="16" ViewCount="10715" Body="&lt;p&gt;Most airplanes fly at &gt;30k feet, way into the stratosphere / mesosphere where sun's UV rays aren't filtered by lower atmosphere layers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the windows of the plane are open and the sun is shinning right on a passenger, will the UV rays be more harmful than those on the earth's surface?&#xA;Are there any long term effects if a passenger is exposed frequently?&lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="1696" LastEditDate="2015-10-07T14:42:23.263" LastActivityDate="2016-10-01T12:49:31.010" Title="Are sun's UV rays more harmful on an airplane at high altitude?" Tags="&lt;weather&gt;&lt;windows&gt;&lt;high-altitude&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21704" PostTypeId="2" ParentId="21703" CreationDate="2015-10-07T07:37:45.873" Score="2" Body="&lt;p&gt;As per &lt;a href=&quot;https://en.wikipedia.org/wiki/Ozone_layer&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ozone_layer&quot; rel=&quot;nofollow&quot;&gt;ozone layer&lt;/a&gt; is from approximately 20 to 30 kilometres (12 to 19&amp;nbsp;mi) above Earth. 30,000 feet is 9.1&amp;nbsp;km which is below the ozone layer, hence the UV rays passing below this range would have been filtered already.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some side effects on skin (cancer) and eye - &lt;a href=&quot;http://www.theozonehole.com/uvrays.htm&quot; rel=&quot;nofollow&quot;&gt;refer&lt;/a&gt; for more details. If this is causing severe problems, then FAA/FAR would have had the regulations to fly below a certain altitude. I don't think there will be any severe effects on the skin as well on the eyes from the UV rays below the ozone layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also per &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=42&amp;amp;sID=505&amp;amp;preview=true&quot; rel=&quot;nofollow&quot;&gt;FAA Safety&lt;/a&gt;, all civil aircraft cannot cross Class A (flying under IFR) airspace cannot exceed FL 600 (~60k ft) which is almost below the ozone layer, so no to the question of exposing to direct UV under these altitudes.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="849" LastEditDate="2015-10-07T20:46:01.097" LastActivityDate="2015-10-07T20:46:01.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21705" PostTypeId="2" ParentId="21703" CreationDate="2015-10-07T07:41:21.383" Score="0" Body="&lt;p&gt;The material of the windows will filter most or all of the UV radiation from the incoming light. That's the reason as well why you don't get a tan driving your car with the windows rolled up (yes, car windows are made of different materials, but the effect is the same).&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Yes, the level of UV radiation at high altitude is more intense than at low altitude, which is why wearing eye protection and protecting the skin against exposure at high altitude is important. &lt;br/&gt;&#xA;But unless you were to fly at 30.000 feet in an open aircraft without windows there's no reason to worry about that when flying. And if your window were to blow out at that altitude you have more serious problems than getting a bit of a sunburn :)&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-10-07T07:41:21.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21707" PostTypeId="2" ParentId="21703" CreationDate="2015-10-07T07:55:11.593" Score="7" Body="&lt;p&gt;You're right. According to the WHO&lt;sup&gt;1&lt;/sup&gt; at 30,000+ feet, UV rays are more intense. They're around 90% more intense, which is enough to cause some pretty nasty skin, and eye damage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot's do have a higher risk of skin cancer&lt;sup&gt;2&lt;/sup&gt;. Although, the jury is out on why this is the case. Most cockpits themselves are made of a different set of materials. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA itself does not have any requirement&lt;sup&gt;3&lt;/sup&gt; specifically on the opacity to UV rays for windows. Though, they point out that typically passenger cabin windows have a protective layer, and typically use some acrylic or polycarbonate. The regulations themselves state the the material must be tolerant to UV exposure itself. Polycarbonate&lt;sup&gt;4&lt;/sup&gt; absorbs most of the UV spectrum. Acrylic on the other hand absorbs UVB, and UVC, the most harmful type of UV radiation&lt;sup&gt;5&lt;/sup&gt;. It, unfortunately, allows some component of the UVA portion of the through (less than 50%&lt;sup&gt;6&lt;/sup&gt;). On top of this, most airlines glaze their windows, blocking even more light. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some modern aircraft utilize electronics in the windows to dim them. The materials that are involved in this allow for better filtering of light, and in addition, allow for the cabin crew to dim the entire cabin in high light situations&lt;sup&gt;7&lt;/sup&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In conclusion, you're a pilot, there may be some higher risk in exposure to UV rays, and you should take appropriate precautions, such as wearing sunscreen. If you're a passenger that flies often, it's probably okay, and no worse than taking a walk in the sun, but if you have very sensitive skin, wearing sunscreen will be an effective way to prevent the little damage that can occur. Fortunately, airplanes are getting more advanced every day, and the risks are becoming fewer, and fewer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sources&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.who.int/uv/faq/whatisuv/en/index3.html&quot;&gt;http://www.who.int/uv/faq/whatisuv/en/index3.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nytimes.com/2012/08/12/travel/faq-frequent-airline-questions.html&quot;&gt;http://www.nytimes.com/2012/08/12/travel/faq-frequent-airline-questions.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25-775-1.pdf&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25-775-1.pdf&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Polycarbonate&quot;&gt;https://en.wikipedia.org/wiki/Polycarbonate&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ultraviolet&quot;&gt;https://en.wikipedia.org/wiki/Ultraviolet&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eplastics.com/Plexiglass_Acrylic_Sheet_UV_Filter&quot;&gt;http://www.eplastics.com/Plexiglass_Acrylic_Sheet_UV_Filter&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/AERO_Q406_article4.pdf&quot;&gt;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/AERO_Q406_article4.pdf&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-10-07T07:55:11.593" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21708" PostTypeId="2" ParentId="21671" CreationDate="2015-10-07T08:02:06.873" Score="3" Body="&lt;p&gt;Generating lift creates downwash. Downwash reduces the effective angle of attack:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/vG1sg.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vG1sg.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.onemetre.net/Design/Downwash/Momentum/AlphaEff.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high aspect ratio reduces the downwash and thus also its reducing effect on the effective angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore a high aspect ratio wing will experience a higher $\alpha_{eff}$ than a low aspect ratio wing at the same angle, and thus stall earlier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same happens with the rudder, but then with $\beta$ instead of $\alpha$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT: clarifying alpha - beta similarity&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in the case of sideslip, we have the following situation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4PZCA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4PZCA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://lib.ugent.be/fulltxt/RUG01/001/805/314/RUG01-001805314_2012_0001_AC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the similarity between the $\alpha$-image above, and the $\beta$-image.&#xA;The mass flow changes direction, and leaves the end of the rudder (more or less) parallel to the rudder chord line. This deviation in airflow direction causes the force to the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So for a normal wing ($\alpha$-image), flow enters straight, leaves going down (downwash) and as a consequence the wings give a force up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the rudder ($\beta$-image), the flow enters straight, leaves going to the right (downwash, but then sideways) and as a consequence the rudder give a force to the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;About the stalling, stalling is not limited to the wings, also rudders can stall if the maximum effective angle they experience is above stalling angle ,and the force generated suddenly drops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we compare two rudders both with the same airfoil and the same $\beta_{eff_{stall}}$, say 10°.&#xA;The $\beta_{stall}$ will be given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ \beta_{stall} - \beta_{downwash} = 10° $$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the $\beta_{downwash}$ is 4° for the low AR wing, and 2° for the high AR wing, it will mean the low AR wing will stall at a $\beta$ of 14° and the wing with the high AR will have a $\beta_{stall}$ of 12°.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-10-07T14:52:15.437" LastActivityDate="2015-10-07T14:52:15.437" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21709" PostTypeId="2" ParentId="21695" CreationDate="2015-10-07T09:02:44.877" Score="6" Body="&lt;p&gt;I've certainly run into my own wake turbulence when doing steep turns in a Cessna 172. In fact, it's the mark of a well-executed 360 degree steep turn that you do feel the bump of running over your own wake after coming full around. :-)&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-10-07T09:02:44.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21710" PostTypeId="2" ParentId="21703" CreationDate="2015-10-07T09:05:12.333" Score="25" Body="&lt;p&gt;Hmmm, opening the window at 30.000ft, where the air temperature is about -40°C/-40°F, air speed is extreme, you can't survive without oxygen, and you want to put your arm outside???&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, if you really do, you'll get a sunburn quite fast. I got a sun burn within an hour in an altitude of 3500m / 12000ft, though I was tanned due to two weeks at the beach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ozone did already absorb a large fraction of the UV-C radiation, but as most of the air mass is already below you, the rest of the sun light will not have been filtered so much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, let's close the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my knowledge, side windows and canopies are made of some kind of polycarbonate &lt;s&gt;like&lt;/s&gt; or Plexiglass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CERN measured the transmission of light through a 2mm sheet of plexigas and came to the result that no light below ~350nm, passes this sheet. Depending on source, the UV region starts below 380-400nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r9XWu.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r9XWu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Source: &lt;a href=&quot;https://cds.cern.ch/record/1214725/files/PH-EP-Tech-Note-2009-003.pdf&quot; rel=&quot;noreferrer&quot;&gt;https://cds.cern.ch&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that the windows are usually thicker, which makes this step in the diagram much steeper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, there isn't much UV left which can cause a sun burn, but let's take the data from &lt;a href=&quot;http://rredc.nrel.gov/solar/spectra/am1.5/&quot; rel=&quot;noreferrer&quot;&gt;rredc.nrel.gov&lt;/a&gt; to calculate how much light you get and compare it to the light at ground. I found a function describing the data from CERN quite well, and applied it to the sun spectrum data (without atmosphere) twice, to get a Plexiglass window of 4mm thickness. So, this is the worst-case, with no air above the aircraft pre-filtering the sunlight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the result, which shows that sunlight is much more intense, and its color is heavily shifted to blue. But the intensity drops to zero, just where the UV-A range starts. Even, if you put the beginning of the UV-A range to 400nm, the intensity is still lower than at the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ofSHs.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ofSHs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind shields of larger aircraft are usually a quite thick composite material of glass and some plastics, which should absorb UV the same way as polycarbonate does, if not better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, I don't see any evidence that you get more UV light in an aircraft than on ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you should not underestimate cosmic radiation, which is absorbed by our atmosphere quite well on the ground, but not at high altitude. A transatlantic flight is equal to an X-ray photography of your chest. Flying staff is an occupation group exposed to much higher radiation doses than any other group and it's dose usually is supervised.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @PeterKämpf pointed out, Plexiglass is only one material used, and it is &lt;em&gt;not&lt;/em&gt; a polycarbonate, which I didn't notice. But polycarbonates don't differ much concerning UV transmission, as the following diagram shows. However, I also read that polycarbonates - in contrast to plexiglass - are not UV hard and need an UV blocking coating when used outside.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ElV3b.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ElV3b.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;Source: &lt;a href=&quot;http://www.plasticgenius.com/2011/05/infrared-and-ultraviolet-transmission.html&quot; rel=&quot;noreferrer&quot;&gt;www.plasticgenius.com&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2015-10-08T08:55:39.310" LastActivityDate="2015-10-08T08:55:39.310" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21711" PostTypeId="1" AcceptedAnswerId="21810" CreationDate="2015-10-07T09:08:36.167" Score="4" ViewCount="401" Body="&lt;p&gt;Is there any way we can predict a crash from the system inputs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question arises &lt;a href=&quot;https://aviation.stackexchange.com/questions/21702/why-black-boxes-are-not-capable-of-transmitting-its-critical-data-directly-to-sa&quot;&gt;from this discussion&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-09T16:11:31.500" Title="Is there any way we can predict an air crash?" Tags="&lt;aircraft-design&gt;&lt;airline-operations&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21712" PostTypeId="1" AcceptedAnswerId="21741" CreationDate="2015-10-07T09:09:05.597" Score="8" ViewCount="1374" Body="&lt;p&gt;I know that for the wing, the Reynolds number is based on the MAC. This makes sense to me, as the boundary layer develops along the length of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what kind of Reynolds number needs to be used if there is a flap behind the main wing and there is flow pattern like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/se61u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/se61u.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aerospaceengineeringblog.com/page/4/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the air particles  will have streamed along the wing before hitting the flap, so I would say then you should use the wing Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, on the flap, also a new boundary layer will start. Particles coming through the gap will only see the flap, and will thus experience a flow with a lower Reynolds number (based on the flap length).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If I'm talking about flow phenomena on the flap, should I be using the global Reynolds number (based on the wing chord), or the local Reynolds number?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="19" LastEditDate="2016-11-23T13:05:32.297" LastActivityDate="2016-11-23T13:05:32.297" Title="When should I use the global Reynolds number and when the local Reynolds number?" Tags="&lt;flaps&gt;&lt;high-lift-device&gt;&lt;reynolds-number&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21713" PostTypeId="2" ParentId="21711" CreationDate="2015-10-07T09:27:22.813" Score="10" Body="&lt;p&gt;Yes, many aircraft are fitted with &lt;a href=&quot;https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TCAS&lt;/a&gt; which predicts one type of crash - an aerial collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many aircraft are fitted with &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_proximity_warning_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;GPWS&lt;/a&gt; which predicts another type of crash - controlled flight into terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ground based ATC have systems that predict a loss of separation, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Short-term_conflict_alert&quot; rel=&quot;nofollow noreferrer&quot;&gt;Short-Term Conflict Alert [STCA]&lt;/a&gt;. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/13090/how-is-a-conflict-between-aircraft-predicted-and-determined&quot;&gt;this question&lt;/a&gt; about separation and conflicts. In terms of predictions this would constitute a very high rate of false positives. But that is good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the predictions, many crashes are avoided.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-09T13:08:15.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21714" PostTypeId="1" AcceptedAnswerId="21736" CreationDate="2015-10-07T10:01:15.433" Score="20" ViewCount="2910" Body="&lt;p&gt;I find myself thinking often, if the seatbelts in airlines are designed just to keep the passengers in seat or to really act as a safety belt like in cars, because in cars which go at 300kmph speed, you have the 5 point seat belt. Why isn't similar approach used for airlines, where the risk is too high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plus articles like &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2141297/Fat-passengers-blast-seat-belts-Scientists-warn-aircraft-safety-failing-American-bellies.html&quot;&gt;these&lt;/a&gt;, suggest heavier / obese passengers are at more risk.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="64" LastEditDate="2015-10-07T15:36:44.897" LastActivityDate="2018-07-18T14:47:29.013" Title="Are the current seat belts used in commercial airlines safe enough?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;seats&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21715" PostTypeId="1" CreationDate="2015-10-07T10:05:25.610" Score="0" ViewCount="191" Body="&lt;p&gt;I know commercial airplanes are gradually becoming safer thanks to the development of systems that are able to &lt;strong&gt;avoid&lt;/strong&gt; the conditions that would lead to a fatality. But is anybody developing systems for minimizing deaths if a plane crashes? For example, cars have airbags and airfighters can eject the pilot's seat in critical situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a little bit disappointing to see that an aircraft's cabin still breaks into pieces when it crashes during takeoff or landing, causing deaths or injuries. Isn't there any way to make the cabin structure more break resistant at landing/takeoff speeds? Wouldn't airbags prevent people hitting their heads against the cabin's walls?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now the probably naivest question: couldn't giant parachutes be installed on airplanes to prevent them from falling in case of stall or engines failure?&lt;/p&gt;&#xA;" OwnerUserId="9745" LastEditorUserId="19" LastEditDate="2016-07-04T15:24:32.200" LastActivityDate="2016-07-04T15:24:32.200" Title="What safety systems are currently being developed for crash situations?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-10-07T11:36:37.700" ContentLicense="CC BY-SA 3.0" />
  <row Id="21717" PostTypeId="1" CreationDate="2015-10-07T10:14:34.550" Score="0" ViewCount="178" Body="&lt;p&gt;I know that in many of the fighter jets, there are canard configurations like in F16, SAAB Gripen etc and heard they increase the aircraft's maneuverability. Can anyone explains how a canard helps in increasing it?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1467" LastEditDate="2018-01-25T09:27:16.427" LastActivityDate="2018-01-25T09:27:16.427" Title="How can the canard configuration increase the aircraft's maneuverability?" Tags="&lt;fighter&gt;&lt;canard&gt;&lt;maneuverability&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2015-10-07T14:23:23.090" ContentLicense="CC BY-SA 3.0" />
  <row Id="21718" PostTypeId="1" AcceptedAnswerId="21720" CreationDate="2015-10-07T10:22:32.690" Score="9" ViewCount="3958" Body="&lt;p&gt;Do stealth-focused aircraft have canard configuration? I believe canards have a negative impact on the radar cross section.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="29026" LastEditDate="2019-02-14T19:33:31.130" LastActivityDate="2019-02-14T19:33:31.130" Title="Do stealth designs have canard configuration?" Tags="&lt;stealth&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21719" PostTypeId="1" AcceptedAnswerId="21723" CreationDate="2015-10-07T10:26:58.673" Score="6" ViewCount="1337" Body="&lt;p&gt;What are the advantages of a variable-incidence wing as used in F-8?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do weight and other issues outweigh the advantages and that's why it's not found in many (any?) other aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="33692" LastEditDate="2020-03-10T08:47:53.667" LastActivityDate="2020-03-10T08:47:53.667" Title="What are the advantages of a variable-incidence wing as used in the F-8?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;vought-f8-crusader&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21720" PostTypeId="2" ParentId="21718" CreationDate="2015-10-07T11:02:02.810" Score="8" Body="&lt;p&gt;So far, no &lt;em&gt;operational&lt;/em&gt; stealth aircraft has had a canard wing as the canards do affect the radar cross section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a few experimental and under development under development aircraft have canards, like the Chengdu J-20.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wgQNL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wgQNL.jpg&quot; alt=&quot;J 20&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:J20_2.jpg#/media/File:J20_2.jpg&quot; rel=&quot;noreferrer&quot;&gt;J20 2&lt;/a&gt;&quot; by V587wiki - Own work. Licensed under CC0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_PAK_FA&quot; rel=&quot;noreferrer&quot;&gt;Sukoi PAK-FA&lt;/a&gt;, on the other hand uses movable Leading Edge Root eXtensions(LERX), which are much more stealthy and are shown drooping down in the following figure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dLmV5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dLmV5.jpg&quot; alt=&quot;PAK-FA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: defenceindustrydaily.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few major drawbacks with the traditional canard designs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Planform alignment&lt;/em&gt; Most of the canards are in aircraft for stability and aerodynamics requirements an as such are not amenable to planform alignment, as their characteristics are sensitive to their shapes and sizes. For example, compare the planform alignment in case of F-22 and Eurofighter Typhoon.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8SZjj.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8SZjj.gif&quot; alt=&quot;Planform alignment&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: forum.keypublishing.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some low observable aircraft, like the Boeing X-36 did  have planform alignment, it is simply that it is difficult to achieve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QjepW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QjepW.jpg&quot; alt=&quot;X 36&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:McDonnell_Douglas_X-36_planform.jpg#/media/File:McDonnell_Douglas_X-36_planform.jpg&quot; rel=&quot;noreferrer&quot;&gt;McDonnell Douglas X-36 planform&lt;/a&gt;&quot; by NASA/Dryden Flight Research Center - &lt;a href=&quot;http://www.dfrc.nasa.gov/gallery/photo/X-36/HTML/EC97-44165-151.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.dfrc.nasa.gov/gallery/photo/X-36/HTML/EC97-44165-151.html&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Canard Angle&lt;/em&gt; Most (not all) of the canards have an anhedral or dihedral due to aerodynamics requirements, which means that they are not in the same plane as the wing and reflect radar waves in other directions, increasing RCS. The following image shows the (mis)alignment of canards with the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xL19P.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xL19P.gif&quot; alt=&quot;Canard alignment&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: forum.keypublishing.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;More reflecting surfaces&lt;/em&gt; Having canards basically means there are two extra surfaces to reflect the radio waves and increase RCS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Interaction with fuselage and wings&lt;/em&gt; The diffracted (radio) waves from the canards can impact on the wings and fuselage and get reflected back, which can increase the radar cross section.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-07T11:47:32.750" LastActivityDate="2015-10-07T11:47:32.750" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21722" PostTypeId="2" ParentId="21719" CreationDate="2015-10-07T12:06:16.507" Score="5" Body="&lt;p&gt;The Vought F-8 Crusader had a variable incidence wing because of the role it was designed to fulfill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vought_F-8_Crusader#Specifications_.28F-8E.29&quot;&gt;F-8&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter#Specifications_.28F-104G.29&quot;&gt;F-104&lt;/a&gt; had comparable performances, but the F-104 was designed to operate from long runways on land, while the F-8 was a naval fighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Higher take-off, approach and landing speed were not an issue on the F-104, so the angle of attack (AoA) was not critical. On landing the '104 could also make use of a drogue chute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand on the F-8 the AoA was critical because of the short, cable-arrested landings on the deck of the aircraft carriers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the relatively small clearance under the fuselage of the F-8, an high AoA during landing could lead to an in-flight engagement of the hook (something definitely undesirable), hence the necessity to keep the fuselage as horizontal as possible.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-10-07T12:06:16.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21723" PostTypeId="2" ParentId="21719" CreationDate="2015-10-07T12:06:24.663" Score="6" Body="&lt;p&gt;The main reason for having variable incidence wing in the F-8 was that it allowed the production of increased lift due to a greater angle of attack without reducing pilot visibility as the fuselage stayed level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft with high angle of attack TO/landings (like delta winged aircraft), pilot visibility is a problem in low speed landings, as the nose will obstruct the runway (or carrier, for that matter) in extreme cases. There are two ways to solve this problem:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Droop the nose, like the Concorde or&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Make the wings variable incidence, like the F-8.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The first option is usually preferred (same thing was done in Tu-144) as the weight penalty is (significantly) less. However, this wasn't possible in the F-8 as the engine air intake was in the nose; so the incidence of wings was changed. The variable incidence wing had the added advantage of reducing the length of landing gear required and improved the low speed characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of Martin XB-51, the variable incidence wings were used to reduce take off distance as it was expected to be operated from forward airfields.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-07T12:22:44.577" LastActivityDate="2015-10-07T12:22:44.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21724" PostTypeId="2" ParentId="21719" CreationDate="2015-10-07T12:08:39.080" Score="3" Body="&lt;p&gt;Tail clearance on take-off and landing and visibility from cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft needed rather high angle of attack on take-off and landing. The resulting attitude would:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;require long gear,&lt;/li&gt;&#xA;&lt;li&gt;provide poor visibility to the pilot and&lt;/li&gt;&#xA;&lt;li&gt;make arrested landings harder, because the centre of gravity would be higher when the hook engages the cable.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So they chose this method of reducing the pitch.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-10-07T12:08:39.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21725" PostTypeId="1" AcceptedAnswerId="21755" CreationDate="2015-10-07T12:59:04.557" Score="18" ViewCount="32747" Body="&lt;p&gt;Looking at the specifications for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330neo#Specifications&quot;&gt;A330neo&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A350_XWB#Specifications&quot;&gt;A350 XWB&lt;/a&gt;, it strikes me that the two under-development models of the A330neo are relatively similar in specification to the A350-800, one slightly shorter and one slightly longer, with corresponding variances in passenger numbers. List pricing (for what little it's worth) is approximately the same, as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, it seems like having two distinct models competing for essentially the same market segment should just increase costs for Airbus, and it's not clear to me what the gains are. Is it easier to sell the A330neo to airlines because of it's relative similarity with the existing A330? Is the A330neo cheaper to operate than the A350 (this seems dubious given cost of operation is one of the big selling points of the A350)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's been some rumours about the A350-800 getting cancelled and customers pushed towards A330neo or larger A350 models; this still counterintuitive to me. Surely having a smaller range of aircraft families (i.e., A320, A350, A380) simplifies a lot (manufacturing, certification, etc.), so why increase the number of families instead of a smaller A350 model?&lt;/p&gt;&#xA;" OwnerUserId="2198" LastEditorUserId="2198" LastEditDate="2015-10-07T15:40:52.607" LastActivityDate="2017-08-22T15:56:11.203" Title="Why is Airbus proceeding with both the A330neo and A350 XWB?" Tags="&lt;airbus-a350&gt;&lt;airbus-a330&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21726" PostTypeId="2" ParentId="21725" CreationDate="2015-10-07T13:17:51.340" Score="9" Body="&lt;p&gt;Actually the A330neo is already eating up into the A350-800 orders so much that &lt;a href=&quot;https://web.archive.org/web/20150316042447/http://www.bloomberg.com/news/articles/2014-07-14/airbus-goes-ahead-with-a330-engine-upgrade-in-787-challenge-1-&quot; rel=&quot;noreferrer&quot;&gt;they have abandoned it&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;“Their A350 strategy has failed -- they’re really down to one successful model,” Boeing Marketing Vice President Randy Tinseth told reporters at the Farnborough expo near London. “If they didn’t make this choice, they’d be headed for a 30 to 35 percent share in the 200- to 400-seat market.”&lt;/p&gt;&#xA;&lt;p&gt;Customer feedback about the A350-800 spurred Airbus’s decision to abandon the plane, said Fabrice Bregier, who leads the airliner unit at the Toulouse, France-based company. Stopping work on that jet will let Airbus focus on the more successful and larger -900 model and respond to some airlines’ concerns for fixes to the biggest version, the -1000.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-08-22T15:55:21.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21727" PostTypeId="2" ParentId="77" CreationDate="2015-10-07T15:28:58.627" Score="3" Body="&lt;p&gt;I have been looking into this recently and have some numbers on hand from people I have spoken to,&lt;/p&gt;&#xA;&lt;p&gt;I now fly out of KDYL but was perviously flying out KPNE, I always asked around for costs at both and this is what I found out. KDYL is a typical small strip in suburban PA, KPNE is a big airport in the northeast corner of Philadelphia (its not Philly international)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Hanger&lt;/strong&gt;: I met a guy at KPNE who co-rented a hanger with 2 other guys from the major FBO there. They were paying 2800 a month (split 3 ways, so just about 940 each). The hanger fit 3 GA planes but was made for a larger regional jet. A tie down at KPNE was a but north of $150 a month from what I heard. Up at KDYL there is a 9 year waiting list for a Hanger (if you can even ever get one) so the thought of renting one there is out. I have yet to get a price on them since they are so hard to come by. Tie downs seem to be under 100 a month there.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Insurance&lt;/strong&gt;: This is highly based on you and your time in type and time over all. Its hard to ballpark&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Annual&lt;/strong&gt;: Most of the Cherokee/172 people I talk to (fixed gear simple stuff) say their annual can be as low or lower than 1500 if nothing is wrong, up to 3000 if a few issues are found and the sky is the limit after that. I have been told by many people at KDYL to find an A&amp;amp;P that will allow owner assisted annuals (you open up and close the plane) which greatly reduces the cost. I have also heard that folding gear can almost double the annual cost but this seems mainly to be when comparing planes like an Arrow and Archer (almost the same plane with the exception of the gear).&lt;/p&gt;&#xA;&lt;p&gt;My buddy has a beautiful '95 Saratoga HP he likes to say that any time anything on the plane breaks its a thousand bucks no matter what it is...&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Engine&lt;/strong&gt;: Most people in the 172/Cherokee world seem to put aside about 10-15 for engine maintenance but more importantly most of these planes actually make it to published TBO numbers. You can read up on it &lt;a href=&quot;http://realcostofownership.blogspot.com/2013/09/engine-overhauls.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; but how much you set aside depends on when you buy the plane. Think about it like this, the idea is to set aside enough for a full overhaul when the engine needs it so a nice equation is&lt;/p&gt;&#xA;&lt;p&gt;(TBO time - Time On Engine at Purchase)/(Cost of Overhaul) = Hourly Engine Set Aside&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Other Maintenance&lt;/strong&gt;: Some people set aside a prop reserve much like an engine reserve. Other things like breaks, spark plugs, tires wear out predictably and may need replacing. You should always have an emergency reserve for when that strange thing breaks that you didn't anticipate.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;IFR&lt;/strong&gt;: there is a nice checklist &lt;a href=&quot;http://flash.aopa.org/asf/ifrinsights_regs/downloads/7-4-RegsCard.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and the full regs &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=ae21a142e1d5d86d12a58b1472c62fa2&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10.3.7.3&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; but the general aircraft IFR requirements are&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;24 Calendar Months&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Static pressure system&lt;/li&gt;&#xA;&lt;li&gt;Altimeter&lt;/li&gt;&#xA;&lt;li&gt;Encoder&lt;/li&gt;&#xA;&lt;li&gt;Transponder&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;30 Days&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;VOR check&lt;/em&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airborne +/- 6 degrees&lt;/li&gt;&#xA;&lt;li&gt;Ground +/- 4 degrees&lt;/li&gt;&#xA;&lt;li&gt;Dual VORs w/i 4 degrees of each other&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;28 Days&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GPS database&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-12T14:09:19.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21728" PostTypeId="2" ParentId="16266" CreationDate="2015-10-07T15:30:35.820" Score="3" Body="&lt;p&gt;This answer is only applicable to civil airline type operations. Military systems do have significantly different requirements which I cannot address.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quick Answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No, they don't have &quot;blind spots&quot; in the sense of areas with no data available.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A TAWS system works differently: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the airline I've worked for, I was &quot;exposed&quot; to Honeywell Mark V EGPWS systems, but I assume that other systems are similar. These systems have a &lt;strong&gt;world-wide&lt;/strong&gt; terrain database. That database and the algorithms take a normal terrain clearance into account as well as the performance of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Holes&quot; or &quot;Corridors&quot; are &quot;cut&quot; into this &quot;terrain clearance carpet&quot; to avoid nuisance warnings when an aircraft &lt;em&gt;needs&lt;/em&gt; to descent below the normal margins. I.e. during landing and takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, these aircraft can safely operate world-wide unless there are new mountains growing (which actually happens with volcanos) or large man-made obstacles are built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with all databases on board of an aircraft, they are updated on a regular basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except for &lt;a href=&quot;https://aerospace.honeywell.com/en/products/safety-systems/enhanced-ground-proximity-warning-system/mk-v-egpws&quot; rel=&quot;nofollow noreferrer&quot;&gt;this link&lt;/a&gt;, I was not able to find an awful lot of information from manufacturers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/98x8p.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/98x8p.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9999" LastActivityDate="2015-10-07T15:30:35.820" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21729" PostTypeId="2" ParentId="21714" CreationDate="2015-10-07T16:13:27.220" Score="-4" Body="&lt;p&gt;Aircrafts' seatbelts are for security reason. And yes, security while flying is &quot;just to keep the passengers in seat&quot; in case of a void or, on ground, in case of a bump or the plane leaning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from that cases, there is no need for a complicate 2/5/10k point system in an impact against a mountain: you will be just plain dead anyway.&lt;/p&gt;&#xA;" OwnerUserId="9830" LastActivityDate="2015-10-07T16:13:27.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21730" PostTypeId="2" ParentId="21680" CreationDate="2015-10-07T16:17:25.317" Score="9" Body="&lt;p&gt;New airliners without a buyer will be handled on a case-by-case basis. Of course manufacturers prefer to not be in such a situation, and there is no standard system for handling this. However, there are some typical ways that this is handled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One option it to &lt;a href=&quot;https://aviation.stackexchange.com/q/10089/1696&quot;&gt;store the aircraft at the manufacturing site&lt;/a&gt;. This is the same (and pretty much only) option that is used for aircraft without engines. This has the advantage of being easier to work in and deliver, but will of course take up valuable space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To save space at the factory, the aircraft can be moved somewhere else. &lt;a href=&quot;https://aviation.stackexchange.com/q/14894/1696&quot;&gt;Storage areas already exist primarily for older aircraft being stored or scrapped&lt;/a&gt;, but &lt;a href=&quot;https://aviation.stackexchange.com/q/2842/1696&quot;&gt;new aircraft can go there as well&lt;/a&gt;. &lt;a href=&quot;http://aviationweek.com/blog/stored-boeing-747-8s-and-other-incredible-photos-mroam&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing has done this with some 747-8 aircraft&lt;/a&gt;, &lt;a href=&quot;http://blog.forecastinternational.com/wordpress/c-17-white-tails-down-to-five/&quot; rel=&quot;nofollow noreferrer&quot;&gt;as well as C-17's&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the manufacturer has spent money assembling the aircraft, and it is costing money to have it sit somewhere, so they will be eager to cut their loss as much as possible. These aircraft will probably be offered at a significant discount compared to placing a new order. However, buyers may prefer to wait and receive an aircraft straight from the factory, rather than one that has been sitting in storage for a while. There may also be issues with customized options applied for an original buyer that would need to be refurbished or accepted by a new buyer. &lt;a href=&quot;http://blogs.wsj.com/corporate-intelligence/2014/07/29/skymark-move-adds-white-tails-to-airbuss-a380-woes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Looking for new buyers&lt;/a&gt; and &lt;a href=&quot;http://www.seattletimes.com/business/boeing-aerospace/boeing-parking-jets-around-puget-sound-the-desert-as-buyers-struggle/&quot; rel=&quot;nofollow noreferrer&quot;&gt;rearranging deliveries&lt;/a&gt; is not unheard of and is part of the business of making aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be that no one is willing to buy an aircraft, or the aircraft would otherwise not be economical to put in service. The aircraft may in this case be sent to a museum, as with the RJX. In a similar case, the first three 787 aircraft were not deemed economical to put into commercial service after the test program, and &lt;a href=&quot;http://www.bizjournals.com/seattle/morning_call/2015/03/tucsons-pima-museum-gets-boeings-unsellable.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;were sent to museums&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last resort would be to &lt;a href=&quot;https://aviation.stackexchange.com/q/20764/1696&quot;&gt;scrap the aircraft&lt;/a&gt;. This is certainly disappointing for a new aircraft, but in some cases it is the only option left to regain any value.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2017-01-14T23:42:17.527" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21731" PostTypeId="2" ParentId="21714" CreationDate="2015-10-07T17:16:55.193" Score="12" Body="&lt;p&gt;&lt;em&gt;Are the current seat belts used in commercial airlines safe enough?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not really, the current seat belt standard is aimed mostly to protect against aircraft movements encountered in flight, not during impact which are very uncommon, contrary to automotive industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25.562-1b.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Current FAA regulations&lt;/a&gt; impose the seat and seat restraints to protect from 16g deceleration using a complex test scenario and simpler 9g test (only the latter before 2009). Some seat belts are fitted with &lt;a href=&quot;http://www.wsj.com/public/article/SB116363703266924532-fbAu94MHDp0pHVgCe6DeZkLsJoE_20061123.html?mod=blogs&quot; rel=&quot;nofollow noreferrer&quot;&gt;an airbag&lt;/a&gt; that expands forwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Why?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a passenger not keen on taking time to understand and adjust a harness, and not willing to remain restrained by a harness for a long time, the compromise is to have a simple belt for flight turbulence, and use the brace position against impact, albeit:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This combination has been proven effective mostly in frontal collision (e.g. in the &lt;a href=&quot;http://flightsafety.org/aerosafety-world-magazine/august-2010/landing-on-the-hudson&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hudson ditching&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Lap belt have shown vertebrae problems in car accidents due to the rapid deceleration of the lumbar region:&#xA;&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rvQgs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rvQgs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.mirus-as.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;).&lt;/sup&gt;&#xA;&lt;BR&gt;&#xA;Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Seat_belt&quot; rel=&quot;nofollow noreferrer&quot;&gt;seat belt&lt;/a&gt;:&lt;br&gt;&lt;br&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Evidence of the potential of lap belts to cause separation of the&#xA;  lumbar vertebrae and the sometimes associated paralysis, or &quot;seat belt&#xA;  syndrome&quot;, led to progressive revision of passenger safety regulations&#xA;  in nearly all developed countries to require 3-point belts first in&#xA;  all outboard seating positions and eventually in all seating positions&#xA;  in passenger vehicles. [...] Besides regulatory changes, &quot;seat belt&#xA;  syndrome&quot; has led to tremendous liability for vehicle manufacturers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Three-point diagonal seat belts, which don't have this problem, are used for helicopters and light aircraft, but are not seen in airliners because the upper anchoring point is not easily available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Better protection used in commercial aviation&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torso restraints are mandatory for the attendants in the US, but attendants are trained to make them effective and are expected to take the time to adjust them correctly so that actual additional benefits over the lap belt can be obtained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qLDjI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qLDjI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2025.785-1B.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC No. 25.785-1B&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In accordance with § 121.311(g), each seat occupied by a flight&#xA;  attendant required by § 121.391(a) must have torso restraint (a&#xA;  combined pelvic restraint and double strap upper torso restraint with&#xA;  a single point release) that meets the requirements of § 25.785,&#xA;  except that any combined safety belt and shoulder harness approved and&#xA;  installed before March 6, 1980, may continue to be used.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;also:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passenger seats occupied by required flight attendants must fully&#xA;  comply with § 25.785(h), including the combined pelvic restraint and&#xA;  upper torso restraint.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-09-04T09:28:01.730" LastActivityDate="2016-09-04T09:28:01.730" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21732" PostTypeId="1" AcceptedAnswerId="21743" CreationDate="2015-10-07T17:29:55.920" Score="5" ViewCount="8610" Body="&lt;p&gt;How do commercial aircraft windshear alert  warning systems work?&lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="8247" LastEditDate="2015-10-07T18:34:57.260" LastActivityDate="2017-11-30T23:48:43.767" Title="How do windshear warning systems work?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21733" PostTypeId="2" ParentId="21732" CreationDate="2015-10-07T18:36:25.190" Score="2" Body="&lt;p&gt;Wind shear warning systems essentially augment the pitot-static system with a radar altimeter and/or GPS. The system bounces radar waves off the ground beneath it to get a true AGL altitude. The system also knows the topology of the region if it's given a GPS fix (GPS can also indicate AGL altitude but it's less precise than a radar altimeter). The warning will sound when the radar altimeter indicates a change in descent rate that isn't matched by the pitot-static system (the VSI will either indicate no change or it will be erratic, as the plane is essentially flying straight and level through a downward-moving mass of air), and not accounted for by known ground elevation changes. This same system can also warn of any dangerous descent rate (descending below a threshold altitude with gear up, at too high a speed, at too great a rate for landing, etc).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-10-07T18:36:25.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21734" PostTypeId="2" ParentId="21714" CreationDate="2015-10-07T18:45:55.070" Score="5" Body="&lt;p&gt;I would postulate (but have no firm evidence to prove the point) that the &lt;em&gt;brace&lt;/em&gt; position is actually safer than a 5-point harness would be for passengers in an aircraft accident. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 5-point harness would hold your body snugly against the seat, but leave your head bobbing around as a 5-pound ball on a weak tether (your neck). The same issue would happen to you in your family car with a 3-point harness, and that's one of the reasons it has airbags installed.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;em&gt;brace&lt;/em&gt; position has your head fairly firmly planted in the furthest forward position already, so your head doesn't whip forward during that sudden stop. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why do race drivers wear a 5- or 6-point harness then? They also wear a &lt;a href=&quot;https://en.wikipedia.org/wiki/HANS_device&quot; rel=&quot;nofollow noreferrer&quot;&gt;HANS&lt;/a&gt; device which effectively &quot;seat belts&quot; their head to the car, as well. The HANS device leaves their head with 1-2 inches of  forward movement and absorbs the stress of impact&lt;sup&gt;*&lt;/sup&gt; with tethers designed for it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;*&lt;/sup&gt;One recent F1 accident saw impact forces upwards of 25G. The driver unbuckled himself and got out of the car while the track marshals were still on their way. I'm sure he was sore, but was really no worse for the wear.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="1467" LastEditDate="2018-07-18T14:47:29.013" LastActivityDate="2018-07-18T14:47:29.013" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="21735" PostTypeId="2" ParentId="21714" CreationDate="2015-10-07T19:05:25.237" Score="4" Body="&lt;p&gt;The short answer is that current airline seats and seatbelt systems are pretty safe when used in accordance with their design criteria. They are not merely decorative - they are tested and proven safety devices.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The longer answer requires looking at the regulations and understanding what the seat/seatbelt/aircraft interior design &lt;em&gt;as an overall system&lt;/em&gt; is intended to do for passengers in the event of an incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current seat belts on FAA-certificated transport-category (airliner) aircraft are governed by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1785&quot; rel=&quot;nofollow&quot;&gt;FAR 25.785&lt;/a&gt;.&lt;br&gt;&#xA;I've excerpted a few relevant bits of that regulation below.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each seat, berth, safety belt, harness, and adjacent part of the airplane at each station designated as occupiable during takeoff and landing must be designed so that a person making proper use of these facilities will not suffer serious injury in an emergency landing as a result of the inertia forces specified in §§&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1561&quot; rel=&quot;nofollow&quot;&gt;25.561&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1562&quot; rel=&quot;nofollow&quot;&gt;25.562&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Straightforward enough: &quot;If we crash people sitting in the seats shouldn't suffer serious injury.&quot;&lt;br&gt;&#xA;The loads the seats and seat belts must withstand are, in part, described in FAR 25.561 and 25.562 which deal with emergency landing conditions - among the requirements are for the seat and seat belt to handle a 9 G forward load with FAA-Standard 170-pound adults.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 170-pound adult certification criteria is why you will find discussions about how larger/heavier individuals are &quot;less safe&quot; -- a heavier individual will impose more load on the seats, seat belts, and attachment points, and may exceed the ultimate limit load of an approved seat/seat belt design.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each occupant of a seat … must be protected from head injury by a safety belt and an energy absorbing rest that will support the arms, shoulders, head, and spine, or by a safety belt and shoulder harness that will prevent the head from contacting any injurious object.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In plain English:&#xA; &quot;Either you need to be secured with a shoulder harness so you can't hit anything, or the seat in front of you needs to be soft and padded so it won't crack your skull open and kill you when you're in the brace position.&quot;&lt;br&gt;&#xA;(This is the same logic used in school busses: Rather than strapping every passenger down with a 5-point restraint we make sure they'll stay in their seat and everything they can hit from a seated position is soft enough that it probably won't kill them.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each seat or berth, and its supporting structure, and each safety belt or harness and its anchorage must be designed for an occupant weight of 170 pounds, considering the maximum load factors, inertia forces, and reactions among the occupant, seat, safety belt, and harness for each relevant flight and ground load condition&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;i.e. &quot;In a worst-case crash a FAA-Standard 170 pound adult shouldn't break the seat or rip the seat belt out of the attachment points.&quot; as I described earlier.  In practice the regulation sets a minimum standard, and most seats will withstand more force than that.  &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-07T19:05:25.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21736" PostTypeId="2" ParentId="21714" CreationDate="2015-10-07T19:09:30.457" Score="16" Body="&lt;p&gt;For a proper answer we first need to define what &quot;safe enough&quot; is. If you want a significant reduction in risk over current standards, improving the restraint &lt;a href=&quot;https://aviation.stackexchange.com/questions/16545/even-after-years-of-research-why-are-planes-unable-to-keep-passengers-alive-in/16553#16553&quot;&gt;will not be enough&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your observation is absolutely correct: The lap belt is the minimum the airlines get away with, and you would be much better protected in some kinds of accident by a proper 5-point harness. But fitting the harness alone will not achieve much: To stay in place in a crash, all seats need to be reinforced, so they can tolerate the increased loads at the shoulder belt attachment points. This will add weight and cut into the profits of airlines, so it will only happen when it is mandated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please read &lt;a href=&quot;https://aviation.stackexchange.com/questions/13793/would-a-roll-cage-plus-a-safety-harness-make-a-small-ga-aircraft-accident-more-s/13800?s=1%7C0.1977#13800&quot;&gt;this answer&lt;/a&gt; for more details. It concerns GA aircraft, but much applies to airliner seats as well. The better the restraints are, the more deceleration load can be survived. Note that the points in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/6411/does-a-prone-position-for-the-pilot-minimize-g-force-effects/6418#6418&quot;&gt;Eiband diagrams shown in this answer&lt;/a&gt; are from tests with additional leg, chest and arm restraints. If all you have is a lap belt, you might probably be able to tolerate only half as many gs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The better alternative to a 5-point harness would be to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11476/why-are-passenger-seats-not-facing-backward-on-an-airplane/11479?s=2%7C0.2051#11479&quot;&gt;turn around all seats&lt;/a&gt;. This would help most to reduce injuries and improve chances of survival in a crash landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I have to contradict @FreeMan: While the brace position will put all the load on a small strip around a person's hips and lets the arms flail forward, a properly secured torso can take 10g for a duration of more than a second and up to 40g momentarily without ripping the head off. See below the famous sequence of Dr. John Stapp in a ride on his rocket sled &quot;&lt;a href=&quot;https://www.youtube.com/watch?v=ob78CkgpcgY&quot; rel=&quot;noreferrer&quot;&gt;Sonic wind&lt;/a&gt;&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CKZQw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CKZQw.jpg&quot; alt=&quot;Dr. John Stapp in a deceleration test&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dr. John Stapp in a deceleration test (picture &lt;a href=&quot;http://www.pbs.org/wgbh/nova/space/gravity-forces.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He clearly had his head bobbing about, but even though he lost dental fillings and suffered hemorrhage in his eyes, the head stayed intact. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, all what the lap belt is really good for is to keep you in your seat with negative acceleration due to gusts. This is by far the most common situation when a restraint is needed. The classical brace position (torso over legs, head down) is impossible anyway in economy class due to the ever reducing seat pitch.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-10-08T05:37:03.283" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="21737" PostTypeId="2" ParentId="12657" CreationDate="2015-10-07T20:36:45.843" Score="0" Body="&lt;p&gt;A canard surface operates in 'clean' air, not 'shadowed' by the wing, so maneuverability has priority over lift.&lt;/p&gt;&#xA;" OwnerUserId="11268" LastActivityDate="2015-10-07T20:36:45.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21738" PostTypeId="2" ParentId="1152" CreationDate="2015-10-07T21:08:11.043" Score="1" Body="&lt;p&gt;'Newtonian' lift is the upward reaction of the wing to its downward deflection of the air-stream.  The most efficient way to deflect the airstream is a gradual acceleration, accomplished by a concave lower surface.  The upper surface shape must prevent premature 'separation' (chaotic vacuum eddies) of the upper airflow.  A symmetric wing can still deflect the air-stream, depending on its angle-of-attack; it has the same lift and drag whether right-side-up or inverted, which is not as efficient as a right-side-up normal wing, but better than an inverted normal wing.&lt;/p&gt;&#xA;" OwnerUserId="11268" LastActivityDate="2015-10-07T21:08:11.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21739" PostTypeId="2" ParentId="21725" CreationDate="2015-10-07T21:56:34.693" Score="3" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;As the years go by more people travel which means bigger aircraft are&#xA;required. The &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a350xwbfamily/a350-800/&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;a350-800&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt; is too small and yes it will probably be&#xA;canceled. Airbus has a lot of customers for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;a330&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt; and they want to&#xA;sell more and if they make the &lt;strong&gt;&lt;em&gt;a330&lt;/em&gt;&lt;/strong&gt; more efficient then the more&#xA;customers want this aircraft. Thats why the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;737MAX&lt;/a&gt;,&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow&quot;&gt;a320NEO&lt;/a&gt;,&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A330neo&quot; rel=&quot;nofollow&quot;&gt;a330NEO&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_E-Jet_E2_family&quot; rel=&quot;nofollow&quot;&gt;E-(75,90,95) e-2,&lt;/strong&gt;&lt;/a&gt;( &lt;strong&gt;and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777X&quot; rel=&quot;nofollow&quot;&gt;777x&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt; are in development&#xA;because of the amount of customers that aircraft has and more&#xA;costumers are going to want the more efficient version.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The &lt;strong&gt;&lt;em&gt;a330NEO&lt;/em&gt;&lt;/strong&gt; design is to directly compete with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;787&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_767&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;767&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt;  The &lt;strong&gt;&lt;em&gt;a350&lt;/em&gt;&lt;/strong&gt; design is against the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;&lt;em&gt;777&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt; and so their goal is to improve thrust and efficiency over the &lt;strong&gt;&lt;em&gt;777&lt;/em&gt;&lt;/strong&gt; with the new &lt;strong&gt;a350&lt;/strong&gt;.&#xA;Thats why they designed both&#xA;aircraft &lt;strong&gt;(&lt;em&gt;a330NEO, a350&lt;/em&gt;).&lt;/strong&gt; Its pricey, but they make a lot of money&#xA;designing both of the aircraft. The &lt;strong&gt;&lt;em&gt;a330&lt;/em&gt;&lt;/strong&gt; is already a very popular&#xA;aircraft and making a version that is more efficient will draw in&#xA;more customers. So in conclusion you can sell many different families&#xA;of aircraft that are popular and increasing efficiency in the&#xA;aircraft will draw in more customers, although it would be very&#xA;pricey Airbus would still make a lot of money from both the &lt;strong&gt;&lt;em&gt;a330NEO&lt;/em&gt;&lt;/strong&gt;&#xA;and the &lt;strong&gt;&lt;em&gt;a350&lt;/em&gt;.&lt;/strong&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-10-07T22:17:26.263" LastActivityDate="2015-10-07T22:17:26.263" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21740" PostTypeId="1" AcceptedAnswerId="21742" CreationDate="2015-10-07T22:24:01.907" Score="3" ViewCount="626" Body="&lt;p&gt;So at the time the A350 didn't exist so I will list the aircraft not including the A350. So it goes A300, A310, A318, A319, A320, A320, A321, A330, A340 then it skips to the A380. So why did Airbus skip a few numbers?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3201" LastEditDate="2015-10-08T07:47:01.307" LastActivityDate="2015-10-08T07:47:01.307" Title="Why did Airbus skip a few numbers when developing the A380?" Tags="&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-10-08T01:55:55.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="21741" PostTypeId="2" ParentId="21712" CreationDate="2015-10-07T23:04:00.677" Score="4" Body="&lt;p&gt;Definitely use the local Reynolds number on each of the flaps! The flap will only work properly if it is allowed to produce its own, fresh boundary layer. If instead it inherits the slow, thick boundary layer of the wing or flap ahead of it, the flow would soon separate and the flap would loose most of its effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that a Reynolds number is always a local phenomenon. At 2 m from the leading edge, the Reynolds number is twice as large as at 1 m. Only when you compare total coefficients for the whole airfoil would the Reynolds number at the trailing edge be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the distance between your bodies is more than a few centimeters, the boundary layers will not interact, so again the local length should be used for the Reynolds number reference length.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-07T23:04:00.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21742" PostTypeId="2" ParentId="21740" CreationDate="2015-10-07T23:27:48.663" Score="7" Body="&lt;p&gt;The question of aircraft name variants &lt;a href=&quot;https://aviation.stackexchange.com/questions/17354/where-do-airplane-variant-numbers-come-from&quot;&gt;have already been discussed&lt;/a&gt;, but I just want to add that other reasons have also been proposed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The '8' in the 380 resembles the double decker configuration of A380.&lt;/li&gt;&#xA;&lt;li&gt;It was named A380 &lt;a href=&quot;https://en.wikipedia.org/wiki/Talk%3AAirbus_A380/Archive_4&quot; rel=&quot;nofollow noreferrer&quot;&gt;because it is twice the size of A340&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;And of course, it is the lucky number for Chinese.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-07T23:36:06.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21743" PostTypeId="2" ParentId="21732" CreationDate="2015-10-08T00:31:25.580" Score="9" Body="&lt;p&gt;Modern commercial airliners have 2 different wind shear protection system:&#xA;1) predictive wind shear warning system&#xA;2) reactive wind shear warning system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These systems work independently. PWS (predictive wind shear) works with weather radar. Reactive wind shear works with FAC ( Flight augmentation computer) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basicly PWS can be switched ON and OFF from the WX-Radar  panel and it has some prerequisite for working : &#xA;Ground speed should be above 30 KTS, WX-Radar should be ON, At least one engine working etc. (may differ with different types).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PWS scans 5 NM ahead from 0-2300 ft and 1500 ft below according to phase of the flight. It works like a doppler radar. It scans the movement of air mass in front of you and &quot;predicts&quot; something goes wrong and warns you according to how bad is the situation. Doppler frequency will shift significantly in case of a microburst so PWS will catch this shift and warn pilots with amber or red cautions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reactive Wind shear system works with on board computers that takes real time data from all sources. This system will be active generally from 50 ft 1300 ft. (may differ) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reactive Wind Shear basiclly monitors aircrafts energy level. For Airbus; FAC is responsible for that. &#xA;In computing the energy level FACs use different data from different sources: ADIRS - air, ground speed, vertical speed , slope. from other sources - wind gradient, vertical wind etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will be active when the a/c energy level goes below predetermined threshold. It will alter from amber to red if your energy losing trend is faster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read this document from airbus includes many general aviation information for more details : &#xA;&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf&quot;&gt;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope it helps. &lt;/p&gt;&#xA;" OwnerUserId="9809" LastActivityDate="2015-10-08T00:31:25.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21744" PostTypeId="1" AcceptedAnswerId="21746" CreationDate="2015-10-08T03:59:16.170" Score="11" ViewCount="8874" Body="&lt;p&gt;I've read about many aircraft systems having redundancies. For example, both Boeing's 787, and Airbus's A380 have a triple-redundant FCS. In this case, it makes sense to act upon the majority's decision. If all three components disagree, how is it decided which one wins? Is there any record of disagreement amongst redundant systems in airplanes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary differences I have compared to the question about Airbus's control systems (&lt;a href=&quot;https://aviation.stackexchange.com/questions/15234/how-does-the-airbus-flight-computers-voting-system-work&quot;&gt;How does the Airbus flight computer&amp;#39;s voting system work?&lt;/a&gt;), is verification for non-deterministic systems, as well as optics for visibility. Given that the entire systems run in parallel up until the verification component (from sensor input, onwards), there will be some, obvious delta in their &quot;decisions.&quot; -- Although, most of the time, this isn't perceivable, is there any visibility into what's going on with the FCS?&lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2017-06-27T21:11:38.640" Title="How do redundancies work in aircraft systems?" Tags="&lt;software&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21745" PostTypeId="1" CreationDate="2015-10-08T04:29:16.917" Score="3" ViewCount="1885" Body="&lt;p&gt;What material are GE engine High Pressure Compressor (spools) made of ? i.e. aluminum, titanium ?&lt;/p&gt;&#xA;" OwnerUserId="11646" LastEditorUserId="3386" LastEditDate="2016-11-23T18:52:36.773" LastActivityDate="2017-05-25T19:49:33.910" Title="What material are High Pressure Compressors made of?" Tags="&lt;jet-engine&gt;&lt;aerospace-materials&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2017-05-26T07:36:27.877" ContentLicense="CC BY-SA 3.0" />
  <row Id="21746" PostTypeId="2" ParentId="21744" CreationDate="2015-10-08T05:53:53.577" Score="11" Body="&lt;p&gt;Triple-redundant systems have four independent members, so if one fails, a two-to-one vote of the remaining three is still possible.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;One system    = No redundancy.&#xA;Two systems   = Simple redundancy.&#xA;Three systems = Double redundancy.&#xA;Four systems  = Triple redundancy.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;However, often the term &quot;triple redundant&quot; is used when the system has only three members. And if all three disagree, two of them must be faulty already, so this is a case of multiple failures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of Airbus, besides the three main FCS computers two backup systems are available to help isolate the faulty one. Inside, each has two channels which run software written by a different team, run on a processor different to the one in the other channel and which are supplied by two different suppliers.  This helps to reduce systematic errors, when all together would fail because of a common malfunction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4UlJy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4UlJy.jpg&quot; alt=&quot;Airbus FCS diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus flight control system diagram (picture &lt;a href=&quot;http://de.slideshare.net/sommerville-videos/airbus-fcs&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Only the first system of each is expanded; the boxes for system 2 and 3 look the same on the inside. Input is from the side sticks, and output goes to the hydraulic valves at the control surfaces. The voting happens first in the comparator step (between the two channels) and again in the filters (between the single systems).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-08T15:13:22.637" LastActivityDate="2015-10-08T15:13:22.637" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21748" PostTypeId="2" ParentId="15269" CreationDate="2015-10-08T08:16:55.977" Score="1" Body="&lt;p&gt;Others have already provided many details on the uses for two-seat fighters, US names and practices, etc. but note that for the Rafale specifically, the two-seat variant is not merely a training version. In fact, some users, including the French Air Force, have more two-seat than single-seat planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The person seating in the second seat is often a “navigator” who assists the pilot and operates the weapon systems but I think that their controls are exactly the same so that the plane could be piloted from the back seat. Note that the Rafale was not designed as a fighter but as “multirole” aircraft, doing everything including reconnaissance, ground attack, close-air support, and nuclear strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some missions benefit from a two-man crew while others do not, hence the two variants. On the other hand, the reason why some planes only have one seat is that the single-seat variant has a lower cost, lower weight and extra fuel tanks.&lt;/p&gt;&#xA;" OwnerUserId="3018" LastEditorUserId="3018" LastEditDate="2015-10-08T17:21:48.083" LastActivityDate="2015-10-08T17:21:48.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21749" PostTypeId="2" ParentId="21744" CreationDate="2015-10-08T10:14:14.940" Score="2" Body="&lt;p&gt;Your question also makes the implicit assumption that redundancy involves multiple systems trying to come up with the same answer.  This isn't necessarily the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've worked on a multiply-redundant hybrid electric vehicle controller.  These things are drive-by-wire as far as go/stop are concerned, so a lot of the same safety principles apply.  A primary control system ran the whole thing, managed emissions, best driver response, and all that good stuff.  A secondary system had a simpler model of how things should behave, checking for when the primary system was outside some tolerance of its simpler model for some time.  Because it was a simpler model, testing could be more complete.  And a tertiary system checked that the primary and secondary systems were coming up with valid behaviour, using an even simpler (and hence even-easier-to-validate) model.  For added fun, the secondary and tertiary systems periodically injected spurious faults and checked their fault-reporting mechanisms were detecting them correctly, so they knew a real fault would trigger correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case the fallback behaviour was simply to pull the plug on the car if the primary system went dodgy, because for a car that's reasonable.  In principle though the secondary system could have been the basis of a perfectly competent fallback strategy if we'd thought it was necessary.&lt;/p&gt;&#xA;" OwnerUserId="11648" LastActivityDate="2015-10-08T10:14:14.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21750" PostTypeId="1" AcceptedAnswerId="21751" CreationDate="2015-10-08T12:03:07.207" Score="9" ViewCount="3336" Body="&lt;p&gt;Some big military cargo carriers carry tanks and other heavy equipment and I am not sure if they have some kind of special locks or tie-downs in the cargo space to manage those heavy loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are these very heavy loads secured?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5517" LastEditDate="2015-10-08T16:12:46.030" LastActivityDate="2020-10-30T02:22:31.883" Title="How is heavy cargo secured in military cargo carriers?" Tags="&lt;cargo&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21751" PostTypeId="2" ParentId="21750" CreationDate="2015-10-08T12:20:40.230" Score="13" Body="&lt;p&gt;The cargo in a military aircraft are secured in the cargo hold using chains, straps etc. connected to stowage tie-down devices, which go into tie-down rings . The following image shows a M1 Abrams tank secured in C-17 Globemaster III using tie-down devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/D2x2R.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D2x2R.jpg&quot; alt=&quot;M1 Abrams tiedown&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;USAF uses three different types of devices to secure cargo in aircraft, which vary in their load capacity:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;MB-1 tie-down device with 10,000 lb rated capacity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;MB-2 tie-down device with 25,000 lb rated capacity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CGU-1/B tie-down device with 5,000-pound rated capacity&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The MB-1 and MB-2 are similar in their form and function, with the only difference being their load capacity.This image shows a close-up of the MB-1 and MB-2 tie-down devices:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TUL5F.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TUL5F.jpg&quot; alt=&quot;C-17 tie-down devices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:C-17_Globemaster_III_no._5139_stowage_tiedown_devices.JPG#/media/File:C-17_Globemaster_III_no._5139_stowage_tiedown_devices.JPG&quot; rel=&quot;noreferrer&quot;&gt;C-17 Globemaster III no. 5139 stowage tiedown devices&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:BrokenSphere&quot; rel=&quot;noreferrer&quot; title=&quot;User:BrokenSphere&quot;&gt;BrokenSphere&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hook goes into the tie-down ring, while on the other end, straps or chains (from the cargo) go. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CGU-1/B is a 20-foot nylon web strap with two metal hooks at both ends. While one hook is stationary, the other hook has a ratchet device and can be moved and tightens the device when it is being used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7sKEb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7sKEb.jpg&quot; alt=&quot;CGU-1/B&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Apparently, &lt;a href=&quot;http://www.designation-systems.net/usmilav/asetds/u-c.html#_CGU&quot; rel=&quot;noreferrer&quot;&gt;Military designation system&lt;/a&gt; refers to MB-1 and MB-2 as CGU-3/E and CGU-4/E respectively.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-08T12:38:59.923" LastActivityDate="2015-10-08T12:38:59.923" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21752" PostTypeId="1" AcceptedAnswerId="21754" CreationDate="2015-10-08T13:11:50.563" Score="13" ViewCount="41049" Body="&lt;p&gt;ETOPS stands for Extended-range Twin-engine Operational Performance Standards, a rule which permits twin engine aircraft to fly routes which, at some point, are more than 60 minutes flying time away from the nearest airport suitable for emergency landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it does not mean that a non-ETOPS plane &lt;em&gt;physically&lt;/em&gt; cannot fly an ETOPS route, as American Airlines proved when they &lt;a href=&quot;http://www.theverge.com/2015/9/13/9320061/american-airlines-accidentally-used-the-wrong-plane-to-fly-to-hawaii&quot;&gt;accidentally used&lt;/a&gt; a non-ETOPS certified plane to operate ETOPS-required LAX-HNL route. Everything went well except the cancelled return flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;strong&gt;what is the difference between an ETOPS certified plane and a non-ETOPS certified plane when they are the same model?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="5517" LastEditDate="2015-10-08T13:20:46.463" LastActivityDate="2018-10-17T23:24:56.043" Title="What is the main difference between an ETOPS certified and non-ETOPS certified plane?" Tags="&lt;airliner&gt;&lt;regulations&gt;&lt;etops&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21753" PostTypeId="2" ParentId="21744" CreationDate="2015-10-08T13:12:35.930" Score="0" Body="&lt;p&gt;In general, the number of redundancy indicates the number of independent members i.e. triple redundancy indicates three independent members, while a quadraplux redundancy indicates four independent members. A triple redundant system used in Flight Control Systems would look something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j78wf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j78wf.png&quot; alt=&quot;Triple redundant system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;A Novel Family of Weighed Average Voters for Fault-tolerant Computer Control Systems&lt;/em&gt; by Latif-Shabgahi et.al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two ways the 'Voter' can determine the output from redundant systems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Agreement based&lt;/em&gt; voting system produces an output only if a certain number (e.g. majority) of the voter inputs agree. This is usually the method used in Flight Control Systems (like Airbus).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The other system produces an output even if there is no agreement between the redundant systems, usually by 'combining' (for e.g. averaging) selecting one of them based on some metric (for e.g. median).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Consider the air data input in case of Airbus: there are three &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_data_inertial_reference_unit#Air_data_reference&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Data and Inertial Reference Unit&lt;/a&gt;s. The input of the 'voter' (&lt;em&gt;each&lt;/em&gt; flight computer) comes from all three ADIRUs. The FCS needs two matching (with some allowed variation) values to generate output. The Flight computers degrade to alternate law or direct law under two circumstances:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;More than one unit fails.&lt;/li&gt;&#xA;&lt;li&gt;No two units agree.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air France flight 447&lt;/a&gt;, the FCS reverted to alternate law due to temporary inconsistency between the measured speeds (likely due to obstruction of the pitot tubes by ice crystals) of two ADRIUs. The another one had already been diagnosed as faulty and excluded from consideration. This and the consequent pilot actions resulted in the crash.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-08T13:12:35.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21754" PostTypeId="2" ParentId="21752" CreationDate="2015-10-08T14:02:12.643" Score="11" Body="&lt;p&gt;The FAA ETOPS certification requires certain standards from &lt;em&gt;both&lt;/em&gt; the airline (the operator) and the aircraft (the manufacturer). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the manufacturers are concerned, the ETOPS certification is given for a particular &lt;em&gt;aircraft-engine combination&lt;/em&gt; satisfying certain requirements. The &lt;a href=&quot;http://frwebgate.access.gpo.gov/cgi-bin/getpage.cgi?dbname=2007_register&amp;amp;position=all&amp;amp;page=1873&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA ETOPS Rules&lt;/a&gt; Section A deals with the Airplane-Engine Type Design Approval. According to the document, the type approval involves a two step process:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First, the FAA determines that airplane systems meet certain design standards for safe operations during an airplane diversion.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some of these requirements are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft should have at least three independent electrical generators.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The auxiliary power unit (APU) (when required) can start after the airplane has been cold-soaked for several hours and can run reliably for the remainder of the flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;System safety analyses have to show that expected system failures will not prevent safe landing at a diversion airport. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Systems with time-limited capabilities (typically cargo fire suppression) need to have the capacity to support a maximum-length diversion,&#xA;including a 15-minute allowance for a hold or go-around at the diversion&#xA;airport&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The second part of the approval process is an evaluation of engine in-&#xA;  flight shutdowns and other significant airplane system failures that have&#xA;  occurred while the airplane-engine combination has been in service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aircraft-engine combination should have at least 250,000 engine-hours for evaluation, though this can be reduced with compensating factors. The airplane-engine combination should maintain a target IFSD (In Flight Shut Down, defined as &quot;When an engine ceases to function (when the airplane is airborne) and is shut down, however briefly, whether self induced, flightcrew initiated or caused by an external influence.&quot;) rate at or below 0.02 per 1,000 engine-hours for 180min ETOPS approval.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer should also demonstrate that flying with OEI doesn't cause undue stresses to the aircrew and is safe for the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ETOPS design approval has to be &lt;em&gt;applied for&lt;/em&gt; with the FAA and obtained after the relevant processes. Thus, the same aircraft will not have ETOPS approval if the engine is different or even the same aircraft-engine combination won't have ETOPS approval if used by another airline or if no certification was sought.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another method of getting ETOPS approval called the 'early' ETOPS approval which &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...takes a systems approach to the development of an airplane and engine. ... an applicant must demonstrate that the design flaws on previously designed airplanes are not present in the new airplane. The applicant must also consider how the maximum length flight and diversion affect the design and function of airplane systems to ensure that they have the capability and reliability for safe ETOPS flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After being ETOPS certified, the airplane-engine combination and the operator are under continuous monitoring with the certificate being withdrawn in case of lapses or if the IFSD rate goes above the target rate and the manufacturer's corrective action does not eliminate the unsafe condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the LAX-Hawaii incident is concerned, according to &lt;a href=&quot;http://www.theguardian.com/us-news/2015/sep/14/american-airlines-wrong-plane-hawaii-flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;American Airlines Spokesman&lt;/a&gt;, both aircraft (the 'correct' ETOPS airplane, A321H and the wrong one sent, A321S) had the same configuration, but&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are two small differences in terms of equipment to allow ETOPS certification. Since you can’t divert for medical [on a Hawaii bound flight], you’re required to carry extra medical oxygen on board and an extra fire suppression canister&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are also reports that the (ETOPS certified) A321H &lt;a href=&quot;http://www.flyertalk.com/forum/american-airlines-aadvantage-pre-consolidation/1583923-2-class-airbus-a321s-32s-32b-sharklets-service-aug-2014-consolidated.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;has extra fuel tanks&lt;/a&gt;, which the (non ETOPS certified) A321S didn't have, though the AA spokesperson had said that the fuel tanks and range were the same.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2018-10-17T23:24:56.043" LastActivityDate="2018-10-17T23:24:56.043" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="21755" PostTypeId="2" ParentId="21725" CreationDate="2015-10-08T14:59:00.820" Score="7" Body="&lt;p&gt;Mainly because of customer concerns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus, or any other aircraft manufacturer can propose a bunch of variants in its catalog, but it's the airlines that defines what aircraft are to be developed next. (On a timeline of 10 years up to 30 years - I don't recall the link, but that's Lufthansa Group's explanation.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the decline of the A340s and 747s, and the success of A330s and 777s (mainly fuel saving and engine maintenance), airlines were in a rush to go twin engined while avoiding mass qualification trainings for a new type as long as possible (A350 and 787). Replacing type for the latest generation counterpart is relevant when a) investment is less than predicted gain, and b) the new type matches traveling volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deal is to attract as much customers as possible from a manufacturer's point of view. The way it is now, you can expect Airbus beating Boeing &lt;em&gt;at that game of both new types and neo ones&lt;/em&gt; as a kind of revenge over the 777 beating the A340. The only market where Boeing is still strong is on aircraft the size of the 767-300ER, and therefore doesn't need a re-engined neo-like, nor a new type, as long as no other manufacturer is capable of building a next gen version on that market. On any other Boeing vs. Airbus market, they are roughly on a draw (737s vs A320s, 777s vs A330s).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;People like to say that the 787 is the successor of the 767. That can be true between the 767-300ER/400ER and a &lt;strong&gt;lightweight&lt;/strong&gt; version of the 787-8, but the comparison stops there, and the 787-9 is likely to get more orders than -8 anyway. In terms of size, the 767-300ER/400ER and 787-8 are very similar. But when you have a look over payload, range, cabin width and fuel consumption, there's a huge gap, and that's what matters for airlines, not size or overall shape. Remember, the 777 was also supposed to be the successor of the 767, but ended on a completely different market.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, because Boeing already has the 777-200ER/LR, it doesn't make sense to launch a successor while the 777 is still strong. That's also why the future 777-X are larger, to make room for the 787-9 and -10, and also why the -10 is supposed to be launched as late as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus, on the other hand, had to drop the A340 program earlier than expected, despite the launching of the -500 and -600 versions. A330s cannot be upgraded like the A340 without heavy structural changes, that's where the A350 enters the stage, and why the A330 is still a good candidate at being re-engined and improved in terms of payload and range. We can say that Airbus were always late to take the lead over Boeing, but that's the result of being as diverse as the countries involved, and the absolute need of a success in bringing the first full length double-decker widebody airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing also made some weird decisions, like the 747-8I (not the freighter), the 767-400ER and the 787-3 (now cancelled). The 747-8I were supposed to seduce Chinese market, and airlines that were historical customers of the 747 production line. But by the time the 747-8I entered service, twin engined long range airliners already took the lead, were proven more fuel efficient, cheaper in maintenance costs and much more versatile, which match with Boeing philosophy towards the point-to-point theory. Filling the gap between the 777-300ER and the A380 wasn't that good of a move. The 767-400ER was neither much more profitable than the 767-300ER, nor the 777-200ER on their respective routes. The 787-3 obviously aimed the Japanese market (and Chinese domestic routes) where 737s/A320s and 767s were still going well. Initially postponed after 787-9 development, it was finally cancelled. Actually, the current Airbus position about the A350 &lt;strong&gt;-800&lt;/strong&gt; is quite the same as Boeing's back then with the 787-3. Difference is, the A350-800 is larger than the 787-3, and is the direct competitor of the 787-8 and -9, and depending on travel trends, probably a strong opponent to the 767-300ER.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing all that, Airbus wouldn't risk shorter or longer versions of the A330, and opted both for one type that can be stretched (A350) to fill the void created by the demise of the A340, and current A330 by increasing the operational service lifetime with the neo version. Next is up to travel trends, which is the most difficult part to estimate...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Having the latest iPlane is seducing, but not everyone can afford it.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3879" LastEditorUserId="14897" LastEditDate="2017-08-22T15:56:11.203" LastActivityDate="2017-08-22T15:56:11.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21758" PostTypeId="1" CreationDate="2015-10-08T16:40:39.290" Score="5" ViewCount="2941" Body="&lt;p&gt;I have been wondering how the mass flow rate is determined by the area of the engine air intake surface and the incoming speed of the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In still air, it is understandable that a stationary engine takes in air at the same rate as it is exhausting based on the preservation of the momentum of the air. Then, the mass flow rate through the engine intake surface can be easily calculated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in still atmosphere with the same engine solely mounted to an aircraft cruising straight, level, and at constant speed $v$, it is not obvious to me how to determine the mass flow rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, keeping the air intake surface area unity, can we determine the mass flow rate based on $v$ alone?&lt;/p&gt;&#xA;" OwnerUserId="11656" LastEditorUserId="5517" LastEditDate="2015-10-08T16:49:42.927" LastActivityDate="2015-10-09T07:11:18.690" Title="How is mass flow rate computed?" Tags="&lt;propeller&gt;&lt;engine&gt;&lt;jet&gt;&lt;propulsion&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21759" PostTypeId="5" CreationDate="2015-10-08T16:50:12.283" Score="0" Body="&lt;p&gt;In regular operations, a twin-engine aircraft must stay within 60 minutes' single-engine flying time of an &lt;a href=&quot;/questions/tagged/airport&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airport&amp;#39;&quot; rel=&quot;tag&quot;&gt;airport&lt;/a&gt; suitable for an emergency landing. This makes certain places in the world (the blue parts of the following map) unreachable for a twin-engine aircraft: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IQrkC.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IQrkC.png&quot; alt=&quot;Areas of the globe unreachable by a twin-engine aircraft without ETOPS are in blue.&quot;&gt;&lt;/a&gt;&#xA;(Image source: &lt;a href=&quot;http://www.boeing.lu/assets/pdf/commercial/airports/faqs/etopseropsenroutealt.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ETOPS (originally &lt;strong&gt;E&lt;/strong&gt;xtended-range &lt;strong&gt;T&lt;/strong&gt;win-engine &lt;strong&gt;O&lt;/strong&gt;perations, now often simply &lt;strong&gt;E&lt;/strong&gt;x&lt;strong&gt;t&lt;/strong&gt;ended &lt;strong&gt;O&lt;/strong&gt;perations, colloquially &lt;strong&gt;E&lt;/strong&gt;ngines &lt;strong&gt;T&lt;/strong&gt;urn &lt;strong&gt;O&lt;/strong&gt;r &lt;strong&gt;P&lt;/strong&gt;assengers &lt;strong&gt;S&lt;/strong&gt;wim) is a rule which permits twin-engine aircraft satisfying certain conditions to fly routes which, for part of their length, are more than 60 minutes' single-engine flying time away from the nearest airport suitable for an emergency landing.  These are primarily long-distance overwater routes (hence the &quot;or passengers swim&quot;), but also include routes over areas of very-sparsely-populated land, such as much of Siberia and parts of the Sahara Desert and &lt;a href=&quot;/questions/tagged/australia&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;australia&amp;#39;&quot; rel=&quot;tag&quot;&gt;australia&lt;/a&gt;'s Outback.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oYzQq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oYzQq.jpg&quot; alt=&quot;etops diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The conditions for an airline to benefit from ETOPS are related to the design, operation and maintenance of certain airplanes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The airframe and engine combination must satisfy ETOPS requirements during certification. &lt;/li&gt;&#xA;&lt;li&gt;The pilots and staff must be trained for ETOPS.&lt;/li&gt;&#xA;&lt;li&gt;Additional flight crew procedures and special engineering must be put in place by the aircraft operator.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;ETOPS approvals are issued with a number denoting how far the aircraft is allowed to be from the nearest diversion airport; for instance, an aircraft with ETOPS-240 approval, such as the &lt;a href=&quot;/questions/tagged/airbus-a330&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a330&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a330&lt;/a&gt;, is allowed to fly routes with segments as far as 240 minutes' single-engine flying time from the nearest diversion airport.  The longest-range ETOPS currently in use is ETOPS-370, held by the &lt;a href=&quot;/questions/tagged/airbus-a350&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a350&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a350&lt;/a&gt;, although &lt;a href=&quot;/questions/tagged/airbus&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus&lt;/a&gt; is shooting for ETOPS-420 (which would allow the A350 to fly as far as seven hours' single-engine flying time from the nearest diversion airport).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first ETOPS flights (not yet referred to as such at the time) were ETOPS-90 flights made by the &lt;a href=&quot;/questions/tagged/airbus-a300&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-a300&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-a300&lt;/a&gt; starting in 1976.  ETOPS-120 was introduced in 1985, followed by ETOPS-180 in 1988 (nowadays, these are often extended by 15%, to ETOPS-138 and ETOPS-207, respectively, to allow these routes to be flown even if one of the diversion airports is closed); ETOPS-240 (first used by the aforementioned A330) was introduced in 2007, ETOPS-330 in 2011 (although the first actual ETOPS-330 revenue flights, by the &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt; and select models of the &lt;a href=&quot;/questions/tagged/boeing-777&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-777&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-777&lt;/a&gt;, did not begin until 2015), and ETOPS-370 in 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;For more information, see Wikipedia.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="22726" LastEditDate="2019-09-19T10:07:03.997" LastActivityDate="2019-09-19T10:07:03.997" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21760" PostTypeId="4" CreationDate="2015-10-08T16:50:12.283" Score="0" Body=" ETOPS (Extended-range Twin-engine Operations, or simply Extended Operations) are a system of rules allowing twin-engine aircraft to fly routes passing further away from the nearest diversion airport than would otherwise be permissible." OwnerUserId="3775" LastEditorUserId="22726" LastEditDate="2019-09-18T23:46:27.200" LastActivityDate="2019-09-18T23:46:27.200" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="21761" PostTypeId="1" AcceptedAnswerId="21764" CreationDate="2015-10-08T17:10:23.137" Score="1" ViewCount="2180" Body="&lt;p&gt;How far are we / Is it even viable to think of a scenario where a drone gets employed to counter a conventional manned fighter? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can see several benefits: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Free of the G-restrictions of a human the drone is free to undergo far more severe manouveres&lt;/li&gt;&#xA;&lt;li&gt;Cheaper testing costs since a drone crash isn't as expensive / as unpalatable as the death of a test pilot&lt;/li&gt;&#xA;&lt;li&gt;More risk appetite during actual combat since a human life is not at stake&lt;/li&gt;&#xA;&lt;li&gt;The removal of the cockpit and life support / protective systems (e.g. No O2 tanks / No pressurization / No ejector seats) leading to a weight reduction, performance improvement and design flexibility. Perhaps allowing greater munitions loads etc. &lt;/li&gt;&#xA;&lt;li&gt;The possibility of undertaking some version of suicidal yet mutually destructive manouveres that are out of question in conventional dogfights. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On the other hand, several limitations I can think of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Poorer field of vision &amp;amp; situational awareness of a remote drone operator operating via cameras and sensors&lt;/li&gt;&#xA;&lt;li&gt;The lag between control and reaction inherent to today's drone remote operator systems. Though how much of this could be improved via better technology is a crucial question. The current generation seems to use Ku band satellite signals. Could some form of ground network (but beyond enemy reach) provide more responsive controls? How close have we approached the fundamental physics latency limits even with existing satellite transmission technology. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;As a totally different alternative, is the possibility of an unmanned, autonomous drone realistic? How far are we on the AI / sensors side where a autonomous decision engine can realistically be a good match for a human adversary in a dogfight. The autonomous option would make the control lag issue redundant.&lt;/strike&gt;  (Redacted to focus the question on manned drones)&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-10-09T14:07:58.803" LastActivityDate="2015-10-09T14:07:58.803" Title="Unmanned Drone vs Conventional Manned Fighter in Combat: How realistic?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;dogfighting&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-10-09T00:17:43.860" ContentLicense="CC BY-SA 3.0" />
  <row Id="21762" PostTypeId="1" CreationDate="2015-10-08T17:51:58.127" Score="1" ViewCount="225" Body="&lt;p&gt;Is there a way to estimate the maximum effective range of a naval radar for air traffic control functionality, based on the radar's stated overall max range?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if a naval radar that has targeting functionality states that it can detect artillery fire at a maximum range of 75NM, is there a way to estimate its range for air traffic control purposes (e.g., a max range of 75NM translates to about a max functional range of 25NM for air traffic control?&lt;/p&gt;&#xA;" OwnerUserId="11658" LastEditorUserId="19" LastEditDate="2016-07-05T09:10:07.970" LastActivityDate="2016-07-05T09:10:07.970" Title="How can the radar range for ATC be estimated based on stated maximum radar range?" Tags="&lt;air-traffic-control&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21763" PostTypeId="1" CreationDate="2015-10-08T18:19:39.893" Score="5" ViewCount="1142" Body="&lt;p&gt;Who invented the canard wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that early planes like those built by Santos Dumont and the Voisin brothers used canard wings but who invented the canard wing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Update&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane built by Hiram Maxim and tested in 1894 had a canard wing for pitch control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Poplf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Poplf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.ctie.monash.edu.au/hargrave/images/maxim_1894_side_elev_1000.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pt0Uy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pt0Uy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://flyingmachines.ru/Images7/Putnam/Pioneers/46-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Hiram Maxim's plane&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it is quite evident that this type of wing was not invented by the Wright brothers as some people believe.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="14897" LastEditDate="2019-02-07T17:43:51.040" LastActivityDate="2019-02-07T18:36:48.533" Title="Who invented the canard wing?" Tags="&lt;aviation-history&gt;&lt;canard&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="21764" PostTypeId="2" ParentId="21761" CreationDate="2015-10-08T18:21:33.260" Score="4" Body="&lt;p&gt;We're nowhere near good enough with our AI for a computer simulant to best a human pilot in a dogfight unless the odds are further stacked against the human (computer flies a superior aircraft, computer has enhanced knowledge of &amp;quot;reality&amp;quot;, computer has advantage in numbers, computer ignores physical limitations of plane or pilot without consequence). Most computer pilot AIs in combat sims are some combination of the very simplistic &amp;quot;locate your opponent, put your lift vector on him and pull up hard&amp;quot; and the more complex &amp;quot;human is doing this, so the best counter-move is this&amp;quot;. There's also no small amount of &amp;quot;I am a game, the purpose of my existence is to be enjoyable for the human, so while I must present a challenge, I must not require my human to attend a year of combat flight school before he stands a chance&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;These are the basics of ACM taught to every fighter pilot, however these strategies will get you shot down against a competent human pilot every time, for two reasons:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&amp;quot;Line up and pull up&amp;quot; tends to settle you into a horizontal &amp;quot;one-circle&amp;quot; turning fight to conserve energy. In that fight, the first pilot to realize it's happening and pull vertical can tighten the turning radius by trading speed for altitude, getting inside and cutting across his opponent's turning circle for a good if somewhat high-offset firing chance. If the opponent sticks with &amp;quot;line up and pull up&amp;quot; he will do just the opposite, trading altitude for speed, increasing his turning radius and putting his tailpipe in front of his opponent's nose.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Moves and countermoves in air combat are a fluid dance that computers are plain bad at. Computers can beat humans in chess because the number of valid moves is fairly low, so the computer can calculate the most advantageous chain of several dozen moves quickly. However, computers are relatively bad at Go, because both the total game tree complexity and the available moves on each player-turn are massive.&lt;/p&gt;&#xA;&lt;p&gt;Air combat is similar; while there are a few basic strategies, there are infinite possibilities, and because air combat, though &amp;quot;turn-based&amp;quot;, involves a different kind of &amp;quot;turn&amp;quot; from those in chess or Go, the computer doesn't get to sit there and think about its move for several seconds; it has to make the best move it can think of in a fraction of a second or else the human will get to make several &amp;quot;moves&amp;quot; before the computer reacts to the first one, and the way computers think, making it decide quickly usually boils down either to simplifying the decision-making or deciding in a random way.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Prioritization is still an area where computer AI is weak. Against one opponent, where your objective is to shoot that opponent down, a computer could do quite well. Facing the primary mission objective of completing a bombing run, with potentially hundreds of aircraft in the sky and thousands of military (and civilian) ground vehicles and people in a combat theater, making the decision of what object deserves your primary attention any given second is something even human pilots don't always do well. Most AIs in combat sims are fairly scripted; either the purpose of an enemy's existence is to shoot down the player, or it focuses on its mission until it cannot ignore the player. Real combat is somewhere in between, especially when your mission is something like CAS or BARCAP where your job isn't one fixed point on the ground or one plane in the air.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Now, computers have some advantages that are considered &amp;quot;cheating&amp;quot; in combat sims but would apply to an unmanned fighter against a manned one. First is the ability to sustain maneuvers in excess of a human's G-limit. As long as the airframe can handle it, the computer can pull 12g turns, or -12g, whatever. Second is that the weight of a human, plus the &amp;quot;man-machine interface&amp;quot; of the cockpit systems, is greater than the mass of a computer directly connected to the instrumentation. The computer is also much faster at working with the aircraft's systems than a human could ever be, so a computer pilot, within a couple seconds of seeing a &amp;quot;blip&amp;quot; on the radar, could have the target locked up, while a human, given the same blip at the same time, would still be slewing tracking gates in the B-scope.&lt;/p&gt;&#xA;&lt;p&gt;A third big advantage is 720* visibility. Humans have about a 170* &amp;quot;cone&amp;quot; of visual response, and a fairly poor 5-10* window of actual focus and acuity. With an unmanned craft, we can install cameras covering virtually 360* around the aircraft in the horizontal and vertical, and have the computer monitor and track objects within the full field of vision, as well as in IR or other non-visible light spectrums, much more efficiently than a human could do the same with the same camera systems.&lt;/p&gt;&#xA;&lt;p&gt;Therefore, the first fully unmanned combat aircraft is very unlikely to look or work like a manned one, because its designers will have done things that would be bad decisions in a manned craft, but will give the computer a maneuverability, speed or visibility advantage that could compensate for more simplistic decision-making of the AI.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-08T18:21:33.260" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21765" PostTypeId="2" ParentId="21758" CreationDate="2015-10-08T18:22:17.110" Score="7" Body="&lt;p&gt;The short answer is: No. One cannot calculate the inlet mass-flow based on the velocity alone. However in order to &quot;know&quot; the velocity ( $v$ ) you most likely would have measured everything you need (see below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your confusion with regards to the in- and outlet mass-flow might be based on the fact that the intake does not &quot;collect&quot; all air upstream depending of the flight-velocity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key is not to think of the geometric area of the intake but the area of stream tube around the air entering the intake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The velocity upstream of the intake is not equal to the air-speed (subsonic flight) because the potential field of the intake decelerates (or accelerates) the flow upstream of the intake and expands (or contracts) the stream tube (from &lt;a href=&quot;https://en.wikipedia.org/wiki/Components_of_jet_engines&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;):&lt;br/&gt; &#xA;&lt;a href=&quot;https://i.stack.imgur.com/yHPN0.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yHPN0.png&quot; alt=&quot;Intake Stream Tubes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to calculate the mass-flow we need to determine the speed and the properties of the air.&lt;br/&gt;&lt;em&gt;(please observe that the air-speed ( $u$ ) at the intake is not equal the free-stream-spped ( $v$ ) )&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually the measured properties are:&lt;br/&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Total Pressure, $p_\mathrm{t}$ (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot_tube&quot; rel=&quot;noreferrer&quot;&gt;Pitot Tube&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Static Pressure, $p_\mathrm{s}$ (&lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot-static_system#Static_pressure&quot; rel=&quot;noreferrer&quot;&gt;Static Pressure Port&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Total Temperauter, $T_\mathrm{t}$ (&lt;a href=&quot;https://en.wikipedia.org/wiki/Total_air_temperature&quot; rel=&quot;noreferrer&quot;&gt;info&lt;/a&gt;, &lt;a href=&quot;http://www.unitedsensorcorp.com/images/TEMPER1.jpg&quot; rel=&quot;noreferrer&quot;&gt;examples&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Relative Humidity, $\varphi$ (for simplicity not used below. Humidity changes the &lt;a href=&quot;https://en.wikipedia.org/wiki/Heat_capacity&quot; rel=&quot;noreferrer&quot;&gt;heat capacity&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The following equations are used to calculate the mass-flow ( $\dot{m}$ ). Simplifications are commonly made for slow speeds unnecessarily excepting a 5% error. The following approach does not use these simplifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equation which needs to be solved in the end is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\dot{m} = A \cdot \rho \cdot u$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neglecting blockage effects and non-uniformities, the density ( $\rho$ ) and the velocity at the inlet ( $u$ ) are unknown and need to be derived from the measured values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First&lt;/strong&gt; the Mach-Number is calculated by solving the following equation &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/isentrop.html&quot; rel=&quot;noreferrer&quot;&gt;(see Nasa)&lt;/a&gt; for the Mach-Number, $M$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{p_\mathrm{s}}{p_\mathrm{t}} = \left( 1 + \frac{\gamma - 1}{2} M^2\right)^{\frac{\gamma}{\gamma-1}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here $\gamma$ is the &lt;em&gt;isentropic coefficient&lt;/em&gt; which is around $1.4$ for air depending on the humidity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second&lt;/strong&gt;, with the Mach-Number, $M$, we can use another isentropic relation to calculate the static temperature, $T_\mathrm{s}$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{T_\mathrm{s}}{T_\mathrm{t}} = \left( 1 + \frac{\gamma - 1}{2} M^2\right)^{-1}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third&lt;/strong&gt;, using the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ideal_gas_law&quot; rel=&quot;noreferrer&quot;&gt;ideal gas law&lt;/a&gt; the density ( $\rho$ ) can be calculated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\rho = \frac{p_\mathrm{s}}{RT_\mathrm{s}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here $R$ is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_constant#Specific_gas_constant&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Specific Gas Constant&lt;/em&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Forth&lt;/strong&gt;, using the equation for &lt;a href=&quot;https://en.wikipedia.org/wiki/Speed_of_sound&quot; rel=&quot;noreferrer&quot;&gt;speed of sound&lt;/a&gt;, $a$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$a = \sqrt{\gamma R T_\mathrm{s}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally &lt;strong&gt;Fifth&lt;/strong&gt;, utilising the definition of the Mach-Number, $M$, the air-speed ( $u$ ) can be calculated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$M = \frac{u}{a}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now all missing values are available to compute the mass-flow.&#xA;This approach can easily expanded to cover humid air by adjusting $R$ and $\gamma$ with respect to the relative humidity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in other answers: The inlfuence of non-uniformity of the flow caused by boundary layers or inlet distortions (e.g. inlet-ducting) need to be corrected using a calibration.&lt;/p&gt;&#xA;" OwnerUserId="11294" LastEditorUserId="11294" LastEditDate="2015-10-09T05:10:59.113" LastActivityDate="2015-10-09T05:10:59.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21766" PostTypeId="1" AcceptedAnswerId="21769" CreationDate="2015-10-08T18:50:48.960" Score="66" ViewCount="28875" Body="&lt;p&gt;Military drones, such as the Predator drone or the Global Hawk, tend to have a weird shape with a whale-like head, and engines concentrated at the back. The wings tend to be of very high aspect ratio, and v-shaped tails seem to be popular:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5ufvW.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5ufvW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NwxJY.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NwxJY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Hwtng.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hwtng.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why aren't there, say, Cessna-shaped drones? If Cessna 172s work fine for human pilots, why not for computer pilots? The Cessna 172's low speed and stability also seems like a good asset for military recon drones.&lt;/p&gt;&#xA;" OwnerUserId="8357" LastActivityDate="2019-03-07T06:34:24.560" Title="Why are military drones shaped so strangely?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="8" CommentCount="5" FavoriteCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="21767" PostTypeId="2" ParentId="21763" CreationDate="2015-10-08T18:54:12.853" Score="3" Body="&lt;p&gt;Short answer? The Wright Brothers. The term was coined to describe the Santos-Dumont 14-bis, as its design with a box-like array of forward control surfaces looked like a duck in flight, but the very first successful powered aircraft was a similar canard biplane with a pusher engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As planes developed after the Wrights' first flight, this design fell out of favor for a number of reasons. To save weight, the horizontal and vertical stabilizers were grouped together so a single set of braces could support them, and when this arrangement was forward of the wings in the most logical pusher configurations of the day, the planes had a general tendency to nose away from the relative wind, which caused issues with takeoff and landing as well as unrecoverable deep stalls as the plane kept its nose high or even swapped ends in a stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These behaviors led to the concept that's familiar to us today, of a central barrel fuselage with the engine and prop in front, the pilot behind that and an &quot;empennage&quot; of horizontal and vertical surfaces in the rear. This arrangement allows for better stability and easier recovery from stalls by having the empennage point the nose into the relative wind, much like a weathervane. The downwash of air over the horizontal stabilizers also allowed that stabilizer to have a reduced pitch angle, reducing drag. These and other advantages led to the arrangement becoming dominant in aircraft design as of WWI (with a couple notable derivations in the early war, like the D.H.2 &quot;pusher&quot; which allowed a machine gun to be mounted along the pilot's line of sight before the invention of the synchronization gear) and continued into the second and third generations of the jet era. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The return to a &quot;pusher&quot;-style powerplant with the modern turbojet led to a revisit of the idea of a forward horizontal control surface. The design has a few advantages, especially in combination with a delta wing which became common on the second-generation supersonic jet fighters. Canards provide a lift force in the direction the pilot wishes the nose to go, instead of opposite that direction, so when pulling up, the canard adds to total lift. Canards also allow the primary pitch surfaces to encounter relatively undisturbed air, as opposed to a tail-mounted stabilizer, which increases the effectiveness of the surface. The larger rearward delta wing acts as the &quot;empennage&quot; of a traditional plane would, helping keep its nose in the wind, and the vertical stabilizer remains at the rear of the plane, avoiding the shortcomings of early canard designs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several experimental designs were tried as early as the war years, but the Saab Model 37 &quot;Viggen&quot; was the first aircraft of the modern era to use a canard-delta planform configuration, in 1967. This design has since become a favorite of European designers, with the Gripen, Typhoon and Rafale all following this basic configuration. The Russians have incorporated canards into a few of their fighters like the Su-30 to augment a traditional all-moving tail elevator, and the PAK FA has a similar concept with movable &quot;leading edge root extensions&quot;. American designers have played with it, in programs like the F-15 ACTIVE tech demonstrator and the XB-70 prototype hypersonic bomber, but the sole production U.S. aircraft to use canards does so mainly for stability; the B-1B Lancer has a small pair of canards linked to the FBW system which dampens oscillations in the forward fuselage.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-08T19:32:39.797" LastActivityDate="2015-10-08T19:32:39.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21768" PostTypeId="2" ParentId="21766" CreationDate="2015-10-08T19:09:18.023" Score="26" Body="&lt;p&gt;Who says they are weird shaped? Maybe the 172 is weird... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is that it's the best design for the mission and the specific application. The 172 is designed to carry people and train young pilots so its characteristics reflect being a good fit of that mission. Drones are required to carry computers and surveillance equipment and often a weapons payload and very specifically, not people. Drones can be of a different shape than a GA plane since pilot ergonomics don't really matter. For what it's worth there are planes that are shaped like the drone you mention. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Bonanza had a long run with the V tail design: &#xA;&lt;a href=&quot;https://i.stack.imgur.com/FthNB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FthNB.jpg&quot; alt=&quot;photo of Bonanza&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://airfactsjournal.com/2012/06/tail-tale-what-was-wrong-with-v-tail-bonanza-pilots/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The new Cirrus Jet has a V tail and a bubble airframe much like the drones you pictured:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/e0PbV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e0PbV.jpg&quot; alt=&quot;photo of Cirrus Jet&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://cirrusaircraft.com/aircraft/vision-sf50/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line is that planes are designed for specific applications and some airframe aspects lend themselves to a given mission better than others. Planes will reflect these constraints over looks 100% of the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side note: low speed is by no means necessary for good recon. The SR-71, which was arguably one of the most successfully spy planes, did plenty of &lt;a href=&quot;https://aviation.stackexchange.com/questions/16320/how-did-sr-71-spy-flying-at-80-000-ft-and-3500-km-h&quot;&gt;recon from 80000ft at Mach 3 with out any problems&lt;/a&gt;.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-10-09T16:06:31.470" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21769" PostTypeId="2" ParentId="21766" CreationDate="2015-10-08T19:21:12.753" Score="113" Body="&lt;p&gt;The whale-shaped forward fuselage covers a parabolic antenna for a high-bandwidth datalink. The operators want to receive the reconnaissance data in real time, and by giving the antenna the best place in the aircraft, it will be able to connect to communications satellites even when they are just above the horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gl8xP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gl8xP.jpg&quot; alt=&quot;Global Hawk cut-away drawing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Global Hawk cut-away drawing (picture &lt;a href=&quot;http://media.defenceindustrydaily.com/images/AIR_UAV_RQ-4_Global_Hawk_Cutaway_lg.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The V-tail of the Predator is an inheritance from its origins as a Navy drone which could be folded to fit into a torpedo tube. Read all about it &lt;a href=&quot;https://aviation.stackexchange.com/questions/7444/does-the-predator-drones-design-make-a-tail-strike-more-likely-on-takeoff-and-l/9929?s=9%7C0.0981#9929&quot;&gt;in this answer&lt;/a&gt;. If you want more info on the benefits of an inverted V-tail, make sure you read KeithS's answer, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Global Hawk the V-tail was chosen to mount the engine above the fuselage for better IR shielding from below. The two tail surfaces also shield the exhaust from the side without affecting aerodynamics negatively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Aerosonde's configuration was chosen after Tad McGeer had experienced in 1990 from the 1/5th scale RC model of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12413/uav-project-in-aerospace-department/12415#12415&quot;&gt;Perseus UAV&lt;/a&gt; of &lt;a href=&quot;http://www.aurora.aero&quot; rel=&quot;noreferrer&quot;&gt;Aurora&lt;/a&gt; that a tail-mounted propeller would &lt;a href=&quot;https://aviation.stackexchange.com/a/3320&quot;&gt;stabilize the aircraft&lt;/a&gt; to the point that it became practically uncontrollable. A &lt;a href=&quot;https://aviation.stackexchange.com/questions/3306/why-are-push-propellers-so-rare-yet-they-are-still-around/3320#3320&quot;&gt;pusher propeller is more efficient&lt;/a&gt; than a tractor propeller, which also explains the propeller location on the Predator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it strikes you how many of the UAVs have V-tails: This allows to use fewer components (surfaces, connectors, actuators), and since all are moved by computer control, the issue of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/3741/how-do-the-beech-bonanzas-ruddervators-work/3744#3744&quot;&gt;mechanical mixer&lt;/a&gt; does not exist. The &lt;a href=&quot;https://aviation.stackexchange.com/questions/9504/what-is-the-difference-between-the-v-shape-tail-and-the-straight-tail-on-the-bee/9509#9509&quot;&gt;lower damping of V-tails&lt;/a&gt; can also be easily tolerated, since the FCS can react much more quickly and commensurately to disturbances than any human pilot. The lower maneuverability possible with V-tails is also not an issue - reconnaissance UAVs fly mostly straight and level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high aspect ratio wings are helping in extending the range and especially the flying time of observation drones. Similar to glider wings, the long and slender wing will offer the lowest drag for a given lift at subsonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, each detail has been chosen deliberately and can be well explained. There is no conspiracy to make UAVs look different from Cessnas.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2019-03-07T06:34:24.560" LastActivityDate="2019-03-07T06:34:24.560" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="21770" PostTypeId="2" ParentId="21762" CreationDate="2015-10-08T19:31:32.543" Score="2" Body="&lt;p&gt;A radar system designed to track artillery shells is likely to be entirely useless as an air traffic control system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To improve their utility radar systems reject signals outside their design parameters. This means that stationary elements (buildings, landscape features, etc.) are ignored, as are objects with velocities well outside the target range. There may be other optimisations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The muzzle velocity of an artillery piece is typically well in excess of the speed of sound (&lt;a href=&quot;http://hypertextbook.com/facts/2003/GabrielaBis.shtml&quot; rel=&quot;nofollow&quot;&gt;Reference&lt;/a&gt;) A radar system designed to handle artillery shells may reject many subsonic traces, and thus ignore most aircraft that you might want to have some control over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, you could reprogram or repurpose the electronics, but then you wouldn't really have a naval radar anymore.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-08T22:11:09.143" LastActivityDate="2015-10-08T22:11:09.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21771" PostTypeId="2" ParentId="21758" CreationDate="2015-10-08T19:50:11.167" Score="3" Body="&lt;p&gt;You need pressure sensors, temperature sensors and flow speed sensors. All three together allow you to calculate the mass flow. Initially, this is done with arrays of sensors to find out about &lt;a href=&quot;https://en.wikibooks.org/wiki/Jet_Propulsion/Intakes#Distortion_avoidance&quot; rel=&quot;nofollow&quot;&gt;intake distortion&lt;/a&gt; and flow inhomogeneity. Once the intake has been calibrated, one discreet sensor of each type will do.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-09T07:11:18.690" LastActivityDate="2015-10-09T07:11:18.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21772" PostTypeId="2" ParentId="21766" CreationDate="2015-10-08T23:40:23.007" Score="52" Body="&lt;p&gt;The biggest reason UAVs look like they do is because they don't need to carry a human, or the life support and avionics displays that human would need. The designs, therefore, are built around what the aircraft does need, mainly communications and viewing/recon equipment in addition to the standard stuff any combat aircraft needs (fuel, weapons, propulsion, lift/control surfaces). The use of a V-tail in practically all of them is for drag reduction; the aircraft doesn't have to be as maneuverable as a manned fighter, so a twin tail with separate all-moving elevators is superfluous, and the lower drag increases flight time for more range or loitering capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A key design consideration in any aircraft is weight balance. The 172, a fairly conventional aircraft design, is designed for a high degree of flexibility in its payload and distribution; the high wing keeps the center of gravity below the center of lift for stability, and by the same token the cockpit and cargo area are under the wing so changes in CG don't cause quite as drastic a change in handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an unmanned aircraft, weight distribution is fairly static; any ordnance is right under the wings and thus the center of lift (fuel is also placed similarly), while the contents of the fuselage besides fuel load hardly change at all between flights. That allows the aircraft designer to allow form to follow function; the front of the aircraft has most of the avionics and communications, counterbalancing the propulsion system at the rear, with the fuel in the middle. The relative size and shape of these three elements is at the designer's discretion, and then the wings are simply placed at or slightly behind the balance point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RQ-1/MQ-1 Predator is probably the weirdest-looking, because in addition to having a V-tail for the weight and drag reasons, the tail is inverted:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pEMSc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pEMSc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inverted V-tail has several advantages in a plane the Predator's size and with the complexity of the total flight system:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A rudder surface placed beneath the CG, as on the Predator, will roll the plane toward the direction of yaw instead of away from it as a top-mounted rudder would, which allows for coordinated turns using only the rudder.&lt;/li&gt;&#xA;&lt;li&gt;This &quot;rolling rudder&quot; behavior is also pretty much all the RQ-1/MQ-1 needs in terms of roll control, so the rudder surfaces can be the only control surfaces on the plane, dramatically simplifying the control layout of the craft. Theoretically the lack of ailerons allows the wings to be removed or folded easily, but the MQ-1 has weapons pylons with firing circuits that complicate this. Larger drones with longer wings have higher MOI in the roll axis, more than the rudders could overcome by themselves, so these designs have ailerons (either wing-warping or hinged), which allows the V-tail to be upright for better ground clearance on landing.&lt;/li&gt;&#xA;&lt;li&gt;A crosswind on an inverted V-tail will cause the plane to pitch up and roll into the wind instead of pitching down and rolling away from it with an upright V-tail. Given the high comms latency between Nevada and Kandahar, this is an advantage, as the plane usually has plenty of room above it to fly while the pilot notices and reacts to the disturbance, but can only fly downward for so long before it runs out of air. Again, larger planes have higher MOIs and so disturbances are more minor.&lt;/li&gt;&#xA;&lt;li&gt;The inverted tail masks a little of the plane's engine noise in flight from specific forward angles. Not much, but every bit helps when you're trying to stay hidden.&lt;/li&gt;&#xA;&lt;li&gt;Lastly, the inverted tail protects the more expensive propeller if the pilot scrapes the back end on the ground. The larger Reaper has more ground clearance to allow for the weapons pylons, and so it can flare more on landing without involving the prop.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The RQ-2 Global Hawk actually doesn't look that farfetched; it bears some resemblance to the A-10 Warthog:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hYCLD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hYCLD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/6Rd0e.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Rd0e.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two aircraft have vastly different mission profiles (the Global Hawk is intended as the U-2's replacement for high-altitude surveillance and reconnaissance while the A-10 is a venerable armor-killer close air support craft), but there's some common design elements, such as the high engine masked by the tail surfaces to reduce IR signature, and the big low wings producing a lot of lift (for a high ceiling in the GH's case, for payload and survivability in the A-10's).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's not similar between the two is program costs; the original A-10As had a unit cost of just \$450k in the '70s, and with new wings and a glass cockpit upgrade the A-10Cs are still just \$11 million a frame. Unit costs of the Global Hawk, including R&amp;amp;D, make the program the most expensive small aircraft to date at \$222 million per unit, eclipsing the &quot;cost is no object&quot; F-22 (\$182m). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other drones are much more cost-efficient; the Predator is just \$4 million each while the larger and more sophisticated Reaper is \$16 million. Losing one still hurts, and the USAF has lost plenty, mainly to operator error (the communications latency inherent in piloting one of these remotely from a ground station half a world away is considerable), but the total costs of these programs is still a pittance compared to any manned airframe in service today, with dramatically reduced maintenance to flight hour ratios and total costs per flight hour. The A-10 is again the cheapest manned combat aircraft in service, costing about \$18,000 per flight hour to operate (no word on what all that price includes; likely some combination of fuel, pilot pay, parts, maintenance and ordnance). The Predator costs just \$3,600 per flight hour, and the Reaper about \$4,800. Again, the Global Hawk program is fairly expensive to operate (about \$49,000 a flight hour) and that's a big reason the U-2 Dragon Ladies that Global Hawk was supposed to replace are still flying (the U-2 is only about \$30,000 a flight hour).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="-1" LastEditDate="2015-10-12T12:10:09.820" LastActivityDate="2015-10-12T12:10:09.820" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="21773" PostTypeId="1" CreationDate="2015-10-09T00:02:15.313" Score="8" ViewCount="5255" Body="&lt;p&gt;An F-22's wing is much different than a wing like the one on the F-16.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This an F-16 wing design:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KUjMY.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KUjMY.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;http://www.aviastar.org&quot; rel=&quot;noreferrer&quot;&gt;www.aviastar.org&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an F-22 wing:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bWxhr.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bWxhr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;http://s3.zetaboards.com&quot; rel=&quot;noreferrer&quot;&gt;s3.zetaboards.com&lt;/a&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a great difference between the 2 wing designs. The F-22 is a very maneuverable aircraft and can out perform almost all the current fighter jets. The YF-23 has a very similar wing design and is considered to be one of the most maneuverable aircraft of all time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why does this wing design give the F-22 and YF-23 such good maneuverability?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The YF-23:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9zuOD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9zuOD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23&quot; rel=&quot;noreferrer&quot;&gt;en.wikipedia.org&lt;/a&gt;) &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="3201" LastEditDate="2015-10-09T16:47:39.847" LastActivityDate="2019-05-08T15:51:13.497" Title="Why does the F-22's wing give it such great maneuverability?" Tags="&lt;wing&gt;&lt;f-22&gt;&lt;f-16&gt;&lt;yf-23&gt;&lt;delta-wing&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21774" PostTypeId="2" ParentId="21773" CreationDate="2015-10-09T00:25:05.867" Score="11" Body="&lt;p&gt;The wing design is different between F-16 and F-22 (which is similar to YF-23) because the requirements were different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing of F-22 (and that of F-23) were designed with stealth in mind, with the wing (and control surface) edges parallel to each other. There was no such design requirement in case of F16.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 is a highly maneuverable aircraft in its own right. However, there are some reasons the F-22 is more maneuverable (i.e. it is super maneuverable) compared to the F-16, most of which are unrelated to wing design.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In general, lesser the wing loading, higher the performance. F22 has a lesser wing loading compared to F-16 (377 kg/m² vs 431 kg/m²). Though this figure will vary depending on various conditions, the F-22 has a lower value, helping in maneuverability.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The F22 has thrust vectoring, which basically acts to increase the control authority and also helps in controlling in high alpha region where the conventional controls would've become unusable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The F22 is maneuverable in the post-stall region, something the F-16 is not capable of. This helps the F-22 in performing maneuvers like the Cobra and Kulbit, which is not possible in F-16.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As a side note, the F-16 VISTA technology demonstrator (which had thrust vectoring) is considered super-maneuverable on par with THE F-22, though it had the same wing. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4197" LastEditDate="2015-10-09T07:10:28.123" LastActivityDate="2015-10-09T07:10:28.123" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21775" PostTypeId="1" CreationDate="2015-10-09T00:27:28.890" Score="5" ViewCount="2115" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23&quot; rel=&quot;noreferrer&quot;&gt;YF-23&lt;/a&gt; was one of the most stealthy aircraft of all time and had a range capability of 2,000 miles (that's more than some airliners can travel) but never entered service. The F-22, has high maneuverable, and is considered to be the second option compared the to YF-23 stealth and speed. So why did the YF-23 never enter service? &lt;a href=&quot;https://i.stack.imgur.com/4Nh1s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4Nh1s.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Image source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Northrop_YF-23_DFRC.jpg&quot; rel=&quot;noreferrer&quot;&gt;NASA/DFRC&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-10-09T18:43:35.723" LastActivityDate="2020-02-05T17:02:46.557" Title="Why did the YF-23 never enter service?" Tags="&lt;experimental-aircraft&gt;&lt;yf-23&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21776" PostTypeId="2" ParentId="21775" CreationDate="2015-10-09T00:36:12.747" Score="10" Body="&lt;p&gt;Because the YF-23 &lt;em&gt;lost&lt;/em&gt; the &lt;a href=&quot;https://en.wikipedia.org/wiki/Advanced_Tactical_Fighter&quot;&gt;Advanced Tactical Fighter&lt;/a&gt; program to YF-22, from which F-22 was developed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, the YF-22 had thrust vectoring and was the more agile of the two.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-09T00:36:12.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21778" PostTypeId="1" AcceptedAnswerId="21780" CreationDate="2015-10-09T01:31:53.933" Score="12" ViewCount="2299" Body="&lt;p&gt;The FARs require a check of the VOR receiver before IFR flight:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1171&quot; rel=&quot;noreferrer&quot;&gt;§91.171&lt;/a&gt;   &lt;strong&gt;VOR equipment check for IFR operations.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless the VOR equipment of that aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;...has been checked using a procedure described immediately following.&lt;/p&gt;&#xA;&lt;p&gt;Does this apply to an ILS approach? Specifically, consider a flight conducted entirely using GPS, except that it terminates in an ILS approach. In most (or all?) aircraft, the ILS and VOR receivers are one and the same. However, the mechanism of how an ILS and VOR work are very different.&lt;/p&gt;&#xA;&lt;p&gt;The FARs speak of &amp;quot;the VOR system of radio naviation&amp;quot;. Is that specifically for actual VORs, or does it encompass the ILS by virtue of being the same receiver and CDI?&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-19T16:53:58.990" Title="Is a VOR check required to legally fly an ILS approach under IFR?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21779" PostTypeId="2" ParentId="21778" CreationDate="2015-10-09T02:11:57.460" Score="3" Body="&lt;p&gt;The VOR receiver check is verifying that the needle can interpret the correct radial within a specified tolerance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears you know how the two separate systems work so a bad VOR check won't affect the accuracy of the localizer system.  Hence, there is no regulation prohibiting it.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-09T02:11:57.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21780" PostTypeId="2" ParentId="21778" CreationDate="2015-10-09T02:18:40.443" Score="7" Body="&lt;p&gt;&lt;strong&gt;This regulation does not apply to an ILS approach.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right is saying that &quot;the VOR system of radio navigation&quot; refers to actual VORs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the flight is conducted using GPS to an ILS approach then you aren't using VOR for navigation. It does not matter that ILS uses the same instrument display.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intuitively, though ILS and VOR use the same display and frequency band, they are functionally different. The VOR beacon sends out a &lt;em&gt;omnidirectional&lt;/em&gt; signal, from which a bearing (0-359 degrees) is calculated. The ILS sends out a focused, directional signal, which the receiver centers on.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-10-09T02:18:40.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21781" PostTypeId="1" AcceptedAnswerId="21792" CreationDate="2015-10-09T03:00:41.343" Score="2" ViewCount="6181" Body="&lt;p&gt;I have taken several flights (in and out) from LAX (Los Angeles International Airport), both domestic and international and have flown in variety of commercial planes (727, 737, 747, 757, 777, 787, A319, A320, A330, A380, turboprops, etc). at various times of day but have always landed/taken off from runway 24L. According to Wikipedia, LAX airport has the following runways.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Runway     Length       Surface&#xA;          ft      m&#xA;6L/24R  8,926   2,721   Concrete&#xA;6R/24L  10,285  3,135   Concrete&#xA;7L/25R  12,091  3,685   Concrete&#xA;7R/25L  11,095  3,382   Concrete&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I'm sure other runways are also used but why does 24L seem most preferred?&lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="1696" LastEditDate="2015-10-09T16:04:17.620" LastActivityDate="2018-06-10T14:06:25.827" Title="Why do my flights always use runway 24L at LAX airport?" Tags="&lt;landing&gt;&lt;airport&gt;&lt;takeoff&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21782" PostTypeId="2" ParentId="21766" CreationDate="2015-10-09T03:10:21.017" Score="10" Body="&lt;p&gt;Another factor:  Cessnas, like virtually all manned aircraft are optimized to get to the destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military drones, however, are more interested in dwell time over the area of interest than in how fast they get there.  This results in a very different optimization than for manned aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also have a very different view of safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have an aircraft that costs \$500k.  There's a safety measure that has a 5% chance of saving the airframe over it's expected life but which costs \$50k.  On a manned plane that's almost certainly going to be done.  On a drone it wouldn't make sense in most cases.&lt;/p&gt;&#xA;" OwnerUserId="2897" LastActivityDate="2015-10-09T03:10:21.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21783" PostTypeId="1" AcceptedAnswerId="21794" CreationDate="2015-10-09T03:10:48.357" Score="12" ViewCount="13947" Body="&lt;p&gt;Perusing through the A/FD in the United States I see that some runways have declared distances while others do not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the meaning of:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;TODA&lt;/li&gt;&#xA;&lt;li&gt;TORA&lt;/li&gt;&#xA;&lt;li&gt;ASDA&lt;/li&gt;&#xA;&lt;li&gt;LDA&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/D22CU.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D22CU.png&quot; alt=&quot;KFMG A/FD Insert&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="1696" LastEditDate="2018-04-19T21:16:42.263" LastActivityDate="2020-07-09T20:13:42.983" Title="What are Runway Declared Distances?" Tags="&lt;aircraft-performance&gt;&lt;aeronautical-charts&gt;&lt;declared-distances&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21784" PostTypeId="2" ParentId="21781" CreationDate="2015-10-09T03:14:34.567" Score="1" Body="&lt;p&gt;Runway 24L appears to be closest to the terminals.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was heard, don't know if it's true), that LAX uses the inner runways (24L / 25R, 06R / 07L) to land and the outer runways to takeoff from (24R / 25L, 06L / 07R)&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-09T03:14:34.567" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21785" PostTypeId="1" AcceptedAnswerId="21786" CreationDate="2015-10-09T03:15:44.677" Score="2" ViewCount="1406" Body="&lt;p&gt;I often play a flight simulator game Infinite Flight (&lt;a href=&quot;http://www.infinite-flight.com&quot; rel=&quot;nofollow&quot;&gt;http://www.infinite-flight.com&lt;/a&gt;) on my iPhone. The game lets you choose the following suffixes with your call sign.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Heavy&lt;/li&gt;&#xA;&lt;li&gt;Super&lt;/li&gt;&#xA;&lt;li&gt;Flight of 2&lt;/li&gt;&#xA;&lt;li&gt;Flight of 4&lt;/li&gt;&#xA;&lt;li&gt;Flight of 5&lt;/li&gt;&#xA;&lt;li&gt;Flight of 6&lt;/li&gt;&#xA;&lt;li&gt;Flight of 7&lt;/li&gt;&#xA;&lt;li&gt;Flight of 8&lt;/li&gt;&#xA;&lt;li&gt;Flight of 9&lt;/li&gt;&#xA;&lt;li&gt;Flight of 10&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I am aware what &quot;Heavy&quot; means but now aware about the rest. Can someone let me know?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks&lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="1696" LastEditDate="2015-10-09T16:08:29.280" LastActivityDate="2015-10-09T16:08:29.280" Title="What are these suffixes used after the call sign?" Tags="&lt;air-traffic-control&gt;&lt;call-sign&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21786" PostTypeId="2" ParentId="21785" CreationDate="2015-10-09T03:23:04.370" Score="6" Body="&lt;p&gt;Heavy - all aircraft with maximum take-off weight greater than 300,000lbs (whether or not they're operating at that weight) It's to highlight to the controller that wake turbulence could be a problem for a following aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Super - Airbus A380: As for 'Heavy', but more so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight of X - All the rest relate to groups or formations containing that number of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These originate in the FAA regulations and are summarised on &lt;a href=&quot;https://en.wikipedia.org/wiki/Call_sign#FAA_aircraft_identification_regulations&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of other unusual suffixes including 'Concorde' (used only by British Airways for the now retired Concorde), Lifeguard (for medical flights), and others&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-09T03:28:28.693" LastActivityDate="2015-10-09T03:28:28.693" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="21787" PostTypeId="1" AcceptedAnswerId="21791" CreationDate="2015-10-09T03:24:06.393" Score="12" ViewCount="966" Body="&lt;p&gt;I sometimes open &quot;Live ATC&quot; app on my iPhone and listen to the &quot;status&quot; of my airplane when I'm taking off until my plane reaches the runway (I know the phone have to be turned off but its exciting to listen to ATC communicating with your pilot). In order to know the status, I have to know the call sign of the plane. If I'm taking off from a small airport, I kinda guess the call sign based on the conversation between the ATC and the pilots and the position of my plane (for example if the ATC says United 220 hold short of Juliet and if my plane is on Juliet, I know my plane is United 220). There have been times when the pilot announces the call sign of the plane before pushback. &#xA;My question is, Is it okay or weird for me to ask the call sign of the plane to the pilots / flight crew during boarding. &lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="19" LastEditDate="2017-03-02T16:14:37.100" LastActivityDate="2017-03-02T16:14:37.100" Title="Is it okay to ask the Call Sign of the plane to Pilots / Flight crew during boarding?" Tags="&lt;call-sign&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21788" PostTypeId="1" AcceptedAnswerId="21826" CreationDate="2015-10-09T03:28:55.057" Score="7" ViewCount="579" Body="&lt;p&gt;See my previous question&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/21783/9491&quot;&gt;What are Runway Declared Distances?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Jeppesen 10-9 or 10-9A charts, there is a section dealing with &lt;strong&gt;Additional Runway Information&lt;/strong&gt;.  Does these distances correspond to the declared distances in the A/FD?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Moi2r.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Moi2r.png&quot; alt=&quot;KFMN 10-9 Chart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="1696" LastEditDate="2018-04-19T21:16:01.747" LastActivityDate="2018-04-19T21:16:01.747" Title="What does the runway distance mean under &quot;Additional Runway Information&quot; on Jeppesen plates?" Tags="&lt;aeronautical-charts&gt;&lt;declared-distances&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21789" PostTypeId="2" ParentId="21781" CreationDate="2015-10-09T03:33:21.970" Score="3" Body="&lt;p&gt;ATC has a very specific flight path that they keep traffic inbound to LAX on.  If you are arriving/departing from/to a northerly direction then you will typically use the north runways.  The opposite is true for the south runways.  They also typically use the inner runways for departures and the outer runways for arrivals.  During less busy times they will allow aircraft to use a runway that is closer to their gate.&lt;/p&gt;&#xA;" OwnerUserId="11662" LastActivityDate="2015-10-09T03:33:21.970" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21791" PostTypeId="2" ParentId="21787" CreationDate="2015-10-09T03:54:55.167" Score="13" Body="&lt;p&gt;Mostly you wouldn't need to ask. Most commercial flights use the airline's standard call sign and the flight number printed on your ticket. Sometimes the call sign can be confusing - British Airways use 'Speedbird'; PAN AM used to use 'Clipper'. There's a list of common callsigns on &lt;a href=&quot;http://www.pilotcareercenter.com/Search-Air-Carrier-By-Name-Region-Aircraft-Type-Radio-Callsign#callsign&quot;&gt;http://www.pilotcareercenter.com/Search-Air-Carrier-By-Name-Region-Aircraft-Type-Radio-Callsign#callsign&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight number should be enough - just listening for calls referring to 'two-two-zero' will almost certainly identify United 220. Code-sharing flights, however, will generally use the flight number of the operating airline. Your ticket might say 'United 220', but if the flight is operated by, say,  American Airlines so the call sign might be 'American 406'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All that said, if you're using your phone when you have been explicitly asked to turn it off the airline is within its rights to confiscate your phone or remove you from the flight.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-09T03:54:55.167" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="21792" PostTypeId="2" ParentId="21781" CreationDate="2015-10-09T03:58:30.110" Score="9" Body="&lt;p&gt;Two words: sample size. Eventually, you will use another one :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are only 4 runways, and they are all used heavily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LAX normally has a westerly traffic flow, with aircraft landing/taking off toward the ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How the airport operates:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At all times, the inboard runways shall be preferred to the outboard &#xA;  runways for departures&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;well over 90% of all operations use the preferred runways&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Quotes from &lt;a href=&quot;https://www.lawa.org/uploadedFiles/LAX/noise/PDF/Final%20LAX%20Preferential%20Runway%20Use%20Policy%20Report%20041114_Web.pdf&quot;&gt;this document&lt;/a&gt;. Nice graphics can be found in there, too.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-10-09T03:58:30.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21793" PostTypeId="1" AcceptedAnswerId="21796" CreationDate="2015-10-09T04:40:58.667" Score="0" ViewCount="338" Body="&lt;p&gt;Why do airlines name themselves for example &quot;Cathay Pacific&quot; or &quot;Virgin Atlantic&quot;. Aren't they indirectly limiting themselves to always fly over &quot;Pacific&quot; or &quot;Atlantic&quot;? It would be weird if Virgin Atlantic flies over Pacific and vice versa. &lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="289" LastEditDate="2015-10-09T06:42:07.307" LastActivityDate="2015-10-09T11:09:58.310" Title="Why do airlines have geographical names in them?" Tags="&lt;airlines&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2015-10-09T14:08:37.303" ContentLicense="CC BY-SA 3.0" />
  <row Id="21794" PostTypeId="2" ParentId="21783" CreationDate="2015-10-09T04:42:31.843" Score="12" Body="&lt;p&gt;From the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM&lt;/a&gt;, 4-3-6 (c)(2):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;All 14 CFR Part 139 airports report declared distances for each runway. Other airports may also report declared distances for a runway if necessary to meet runway design standards or to indicate the presence of a clearway or stopway. Where reported, declared distances for each runway end are published in the Airport/Facility Directory (A/FD). For runways without published declared distances, the declared distances may be assumed to be equal to the physical length of the runway unless there is a displaced landing threshold, in which case the Landing Distance Available (LDA) is shortened by the amount of the threshold displacement.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Now for definitions. These terms are defined by the FAA/ICAO in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/PCG_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;PCG&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;TODA - Takeoff Distance Available.&lt;/strong&gt; The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;TORA - Takeoff run available.&lt;/strong&gt; The runway length declared available and suitable for the ground run of an airplane taking off.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;ASDA - Accelerate-Stop Distance Available.&lt;/strong&gt; The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;LDA - Landing Distance Available.&lt;/strong&gt; The runway length declared available and suitable for a landing airplane.&lt;/p&gt;&#xA;&lt;p&gt;(also &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway#Declared_distances&quot; rel=&quot;noreferrer&quot;&gt;Declared Distances&lt;/a&gt; from wikipedia)&lt;/p&gt;&#xA;&lt;p&gt;which lead to other definitions...&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Stopway&lt;/strong&gt; - An area beyond the takeoff runway no&#xA;less wide than the runway and centered upon the&#xA;extended&#xA;centerline of the runway, able to support the&#xA;airplane during an aborted takeoff, without causing&#xA;structural damage to the airplane, and designated by&#xA;the airport authorities for use in decelerating the&#xA;airplane during an aborted takeoff.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Clearway&lt;/strong&gt; - An area beyond the takeoff runway&#xA;under the control of airport authorities within which&#xA;terrain or fixed obstacles may not extend above&#xA;specified limits. These areas may be required for&#xA;certain turbine-powered operations and the size and&#xA;upward&#xA;slope of the clearway will&#xA;differ depending on&#xA;when the aircraft was certificated.&lt;/p&gt;&#xA;&lt;p&gt;then for those &lt;code&gt;specified limits&lt;/code&gt; of the clearway, in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.1.1&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Part 1&lt;/a&gt; we find&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Clearway means:&lt;/p&gt;&#xA;&lt;p&gt;(1) For turbine engine powered airplanes certificated after August 29, 1959, an area beyond the runway, not less than 500 feet wide, centrally located about the extended centerline of the runway, and under the control of the airport authorities. &lt;em&gt;&lt;strong&gt;The clearway is expressed in terms of a clearway plane, extending from the end of the runway with an upward slope not exceeding 1.25 percent, above which no object nor any terrain protrudes.&lt;/strong&gt;&lt;/em&gt; However, threshold lights may protrude above the plane if their height above the end of the runway is 26 inches or less and if they are located to each side of the runway.&lt;/p&gt;&#xA;&lt;p&gt;(2) For turbine engine powered airplanes certificated after September 30, 1958, but before August 30, 1959, an area beyond the takeoff runway extending no less than 300 feet on either side of the extended centerline of the runway, at an elevation no higher than the elevation of the end of the runway, clear of all fixed obstacles, and under the control of the airport authorities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-09T14:05:35.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21795" PostTypeId="2" ParentId="21793" CreationDate="2015-10-09T05:52:23.153" Score="2" Body="&lt;p&gt;The naming of an airline completely left to the investor(founder) who is registering the airline name. Reason behind the naming for the one you are referring &quot;Cathy Pacific&quot; is Cathay, the ancient name given to China and Pacific because Roy Farrell (one of the founding member of airline) speculated that they would one day fly across the Pacific. More on this can be found &lt;a href=&quot;https://en.wikipedia.org/wiki/Cathay_Pacific&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be a reason behind the name or may not be. I feel that it is not necessary to have a particular reason behind the airline naming or even other naming convention.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-10-09T05:52:23.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21796" PostTypeId="2" ParentId="21793" CreationDate="2015-10-09T06:10:23.620" Score="4" Body="&lt;p&gt;&lt;strong&gt;In a lot of cases it's because they started serving a specific region.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lucky tells the story of Cathay Pacific. &lt;a href=&quot;https://en.wikipedia.org/wiki/Virgin_Atlantic&quot; rel=&quot;nofollow&quot;&gt;Virgin Atlantic was started specifically to fly from Britain across the Atlantic&lt;/a&gt;. Lots of US airlines started in a specific region, like Southwest. &lt;a href=&quot;https://en.wikipedia.org/wiki/WestJet&quot; rel=&quot;nofollow&quot;&gt;Westjet&lt;/a&gt; started serving the west of Canada.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't make sense to change a well-known name just because the reach of the airline is extended.&lt;/p&gt;&#xA;" OwnerUserId="289" LastActivityDate="2015-10-09T06:10:23.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21798" PostTypeId="1" AcceptedAnswerId="21805" CreationDate="2015-10-09T10:34:12.963" Score="12" ViewCount="3657" Body="&lt;p&gt;A landing in Costa Rica has recently caught some attention in media, for example &lt;a href=&quot;http://www.dailymail.co.uk/news/article-3265088/Passenger-jet-misses-motorists-just-yards-nail-biting-footage-grazes-perimeter-fence-landing-Costa-Rica.html&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flight from Madrid to San Jose allegedly experienced difficult winds and the pilots changed the descent pattern accordingly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They approached the runway at a very low altitude, scaring both passengers and people on the ground. And considering the footage available in the article, I don't blame them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The authorities however claim that this was a normal and controlled landing, and that there are no limits how low the approach is allowed to be over the area close to the runway. They admitted, though: &quot;Sure it could have been a little higher, but the altitude and angle of the plane was fine.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the authorities right about this, or should the media's, the passengers' and the locals' concerns be taken seriously?&lt;/p&gt;&#xA;" OwnerUserId="11665" LastEditorUserId="11665" LastEditDate="2015-10-09T10:42:12.800" LastActivityDate="2015-10-09T21:50:14.337" Title="Costa Rica landing in the news, concerns to be taken seriously?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21799" PostTypeId="1" AcceptedAnswerId="21803" CreationDate="2015-10-09T11:09:38.540" Score="7" ViewCount="6641" Body="&lt;p&gt;According to potential flow theory, we know that the lift generated by the wings is due to the vortex it creates. In case of a 3D finite wing, there is also a span wise flow due to tip leakage from bottom to upper surface. So if suppose the wing is moving towards left, then the direction of vortex should be clockwise, which in turn should produce an &lt;strong&gt;upwash rather than downwash&lt;/strong&gt;. This should cause an increase in angle of attack rather than decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the downwash generated should be valid for a wing travelling behind the original wing, but we say that there is downwash on the original wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So where is it that I am making a mistake, vortex direction. If yes, what is the correct explanation. Please explain.&lt;/p&gt;&#xA;" OwnerUserId="3029" LastActivityDate="2019-02-23T19:57:39.830" Title="Why does the vortex created by wing affects its own angle of attack?" Tags="&lt;aerodynamics&gt;&lt;wing-tip-vortex&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21800" PostTypeId="2" ParentId="21793" CreationDate="2015-10-09T11:09:58.310" Score="0" Body="&lt;p&gt;The name of a business is the business's brand name so people can identify it easily. It is totally separate from what the business does, or in the case of airlines where it flies. Its just a name and it is up to the owner to decide what the business is called and when (if ever) to change it. The names of airlines often come from the place that the airline started operations but there is no rule saying this must be so. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no rule stating you have to call the airline by the places it actually flies over. Generally changing names of businesses can confuse customers, so it is not done very often. I would think also that airlines are proud of their history so that's another reason not to rename just because they created a new route.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-10-09T11:09:58.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21801" PostTypeId="2" ParentId="21798" CreationDate="2015-10-09T11:10:41.793" Score="68" Body="&lt;p&gt;Please don't link to media articles in the general press, but especially not the Daily Mail who generally don't worry too much about facts and have no-one on staff who has a clue about aviation (&amp;quot;activate their tyres in time&amp;quot;, &amp;quot;With its landing gear ejected, the plane comes perilously close to hitting ground level too early&amp;quot;).&lt;/p&gt;&#xA;&lt;p&gt;Just look at the rhetoric in the wording of the article body.  It ticks all the boxes:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...within a few feet of terrified drivers...&lt;/p&gt;&#xA;&lt;p&gt;...Shocked passengers on board...&lt;/p&gt;&#xA;&lt;p&gt;...eye-catching video...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The Daily Mail tries to get at least one of these a month as clickbait and for comments.&lt;/p&gt;&#xA;&lt;p&gt;Some critical thinking.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...grazed perimeter fence...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;No evidence presented.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...why so many photos...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Because the road is right at the end of the runway and spotters gather there to take such photos.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...passengers shocked...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;No evidence presented and most passengers are the worst possible judges of a good approach or not. How would they know?&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...how low was it at the threshold?...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;No evidence presented.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;...airport authorities insist it was a normal and 'controlled landing'...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;What evidence is there that it was not?&lt;/p&gt;&#xA;&lt;p&gt;SJO is known for its tricky and low approaches.  &lt;a href=&quot;https://www.youtube.com/watch?v=x5ay8C3rvsI&quot; rel=&quot;noreferrer&quot;&gt;Nothing to see here.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-09T21:50:14.337" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21802" PostTypeId="1" AcceptedAnswerId="21806" CreationDate="2015-10-09T11:18:30.867" Score="15" ViewCount="19508" Body="&lt;p&gt;What kind of materials is being used for Fighter jets glass shields and is that different from what they use for commercial jets?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="12220" LastEditDate="2016-06-08T14:48:15.650" LastActivityDate="2017-04-24T19:35:52.730" Title="What kind of materials is being used for Fighter jets glass shields?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21803" PostTypeId="2" ParentId="21799" CreationDate="2015-10-09T11:20:33.450" Score="9" Body="&lt;p&gt;The wingtip vortices create both upwash and downwash; The downwash lies within the wingspan and affects the wing angle of attack while the upwash region lies outside the wingspan and can be utilized by another aircraft (or bird) flying behind and above the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flow induced by the downwash reduces the effective angle of attack of the (finite) wing and causes the induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See if this image clarifies your doubt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WEBH6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WEBH6.jpg&quot; alt=&quot;trailing edge vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: aerospaceweb.org&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Consider the upwash before the wing and downwash after the wing (section).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Znlb2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Znlb2.jpg&quot; alt=&quot;Upwash and downwash&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: theairlinepilots.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it can be seen, the airflow in front of the wing is slightly directed &lt;em&gt;upwards&lt;/em&gt; by the upwash. Now, the angle the wing makes with the horizontal datum (i.e. relative airflow) is the same. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the airflow is slightly turned upwards and the wing &lt;em&gt;sees&lt;/em&gt; the air coming at it at a different angle compared to the relative airflow. As a result, the effective angle of attack (defined as the angle of attack that lies between the chord of an airfoil and the effective airflow) is &lt;em&gt;reduced&lt;/em&gt;, so that the relative and effective airflow looks something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6Fpra.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Fpra.jpg&quot; alt=&quot;Effective airflow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: theairlinepilots.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This difference between the relative and effective airflows is what that causes the induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FHNMm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FHNMm.jpg&quot; alt=&quot;Induced drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: theairlinepilots.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-09T18:03:38.967" LastActivityDate="2015-10-09T18:03:38.967" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21804" PostTypeId="2" ParentId="21802" CreationDate="2015-10-09T11:44:36.787" Score="17" Body="&lt;p&gt;The fighter jet canopies usually are &lt;a href=&quot;http://www.sae.org/aeromag/techupdate_6-00/04.htm&quot; rel=&quot;noreferrer&quot;&gt;made of (special) acrylic plastics&lt;/a&gt; or polycarbonate, with special coatings for RCS reduction in some cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, different fighter canopies differ in their material and construction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 canopy is the largest piece of monolithic polycarbonate material being formed today. It has no canopy bow (frame) which helps in having superior optics throughout the canopy (not just in the front) and also offers the requisite low-observable features.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/reFGc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/reFGc.jpg&quot; alt=&quot;F 22 canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.abovetopsecret.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The canopy is 3/4&quot; thick and is actually made of two 3/8&quot; thick sheets that are heated and fusion bonded (the sheets actually meld to become a single-piece article) and then drape forged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, F-16's canopy, is made up of laminated polycarbonate-acrylic canopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m6j63.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m6j63.jpg&quot; alt=&quot;F-16 canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: designer.home.xs4all.nl&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, a laminated canopy offers better birdstrike protection; however, lamination also adds weight as well as reduced optics. Some aircraft have gold tinted canopies like the EA6B Prowler.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8zwcH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8zwcH.jpg&quot; alt=&quot;EA6B Canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:EA-6B_Prowler_takes_off_from_Eielson_AFB.jpg#/media/File:EA-6B_Prowler_takes_off_from_Eielson_AFB.jpg&quot; rel=&quot;noreferrer&quot;&gt;EA-6B Prowler takes off from Eielson AFB&lt;/a&gt;&quot; by Camera Operator: SSGT CHERIE A. THURLBY, USAF - ID: DFSD0405331 / 020423F7203T025]. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gold tinting performs two different functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;On an EA-6B it serves to protect the crew from the radiation emitted by their own jamming pods (EA6B can carry upto 5 jamming pods). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On other aircraft like F-16 and F-22, it prevents radiation (from Radar) from reflecting off the interior cockpit structure, reducing RCS. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/673/what-materials-are-plane-windows-made-of&quot;&gt;Commercial jets use Plexiglas or Poly(methyl methacrylate) (PMMA)&lt;/a&gt; in their windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources: &lt;a href=&quot;http://www.ppgaerospace.com/About-Us/History.aspx&quot; rel=&quot;noreferrer&quot;&gt;PPGaerospace&lt;/a&gt;, &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/f-22-cockpit.htm&quot; rel=&quot;noreferrer&quot;&gt;globalsecurity.org&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-10-09T15:51:15.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21805" PostTypeId="2" ParentId="21798" CreationDate="2015-10-09T11:59:12.773" Score="21" Body="&lt;p&gt;I would like to point out a few things in your source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, look at the bottom right picture. It shows an altitude of about 30 feet, guessing that an average airport fence is about 9 feet high (forgive me if I'm a little bit off, I usually use SI units). Then, if you look more closely, you see that the plane is not actually right above the fence at that point, but quite a bit past it, which means that it was higher when it passed the fence. So, no big problem there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then the pictures of the bottom of the airplane. You notice how the airplane looks very distorted, like it has a massive nose. This is because smartphone cameras generally have wide-angle lenses - an extreme example would be a fish-eye lens. They &lt;strong&gt;severely&lt;/strong&gt; distort the intuitive concept of distances (closer looks VERY close, further away looks VERY far away)- if you try to inspect it a little bit more carefully, suddenly you realize the plane is about 4-5 times the height of the quite large tree in the center of the picture. Again, no big problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there's the picture of the plane going over the road. This is shot with a narrow angle lens (probably a good zoom lens or even a telephoto lens). This has the opposite effect of a wide-angle lens: things that are in reality separated a lot look really close to each other - my favorite example being &lt;a href=&quot;http://1.bp.blogspot.com/-ARrUx58VlWU/UMyvaxVe2zI/AAAAAAAAC48/N6lfpnW1ins/s640/fighter-jet-fly-by-10149-1247770113-7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; picture. So, while it looks like it's directly at the top of the hill, in reality it's probably much further away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, finally: even if &lt;strong&gt;all of the above were false&lt;/strong&gt;, it still wouldn't be a big problem. A stabilized approach is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1271/what-is-a-stabilized-approach&quot;&gt;stabilized approach&lt;/a&gt;. A lower glide angle makes some things quite a bit easier: your engines are spooled up higher which makes them more reactive, and your touchdown will be smoother than Mick Jagger's moves. Downsides: more fuel consumption, more noise and usually more turbulent winds, which was specifically not the case according to the story (indeed, they went low to &lt;em&gt;avoid&lt;/em&gt; those winds).&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-09T11:59:12.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21806" PostTypeId="2" ParentId="21802" CreationDate="2015-10-09T12:41:53.437" Score="24" Body="&lt;p&gt;Today, the canopy is a multi-layer structure. In case of the F-16, it consists of three layers:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The innermost layer is 0.5 inch thick polycarbonate and drape-molded into the compound curvature shape.&lt;/li&gt;&#xA;&lt;li&gt;The center layer is 0.05 inch polyurethane to bond the inner to the outer layer.&lt;/li&gt;&#xA;&lt;li&gt;The outer layer is a 0.125 inch layer of acrylic (PMMA).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The canopy is bolted to a metal frame for assembly. Some canopy also use &lt;a href=&quot;https://aviation.stackexchange.com/questions/12821/what-are-these-wavy-lines-on-fighters-canopy&quot;&gt;explosive cord&lt;/a&gt; on the outer layer to fracture the material shortly before the ejection seat fires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fa1NS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fa1NS.jpg&quot; alt=&quot;F-16 canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 canopy (picture &lt;a href=&quot;http://s1160.photobucket.com/user/MyF16Sim/media/F-16Canopy.jpg.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For less fast aircraft, a single layer of acrylic is sufficient. Funnily, the &lt;a href=&quot;http://www.mecaplex.ch/mecaplex.asp?s=925&amp;amp;l=en&quot; rel=&quot;noreferrer&quot;&gt;company which produces most of those canopies&lt;/a&gt; doesn't even have a page in Wikipedia. They use flat PMMA sheets and drape-mold them over a mandrel. The secret of their process is the grease they put on the mandrel so the acrylic flows easily into shape.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-10-09T14:13:52.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21807" PostTypeId="1" AcceptedAnswerId="21808" CreationDate="2015-10-09T13:39:51.177" Score="1" ViewCount="399" Body="&lt;p&gt;Is it is possible in real life to make a aircraft carriers size ships to fly in the sky like the flying things we seen in avengers movie?&lt;/p&gt;&#xA;" OwnerUserId="11668" LastEditorUserId="11668" LastEditDate="2015-10-09T17:18:19.003" LastActivityDate="2015-10-09T17:18:19.003" Title="Is it possible to lift a ship sized vehicle into the sky by following modern day aerodynamics and aircraft design?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21808" PostTypeId="2" ParentId="21807" CreationDate="2015-10-09T13:57:02.583" Score="6" Body="&lt;p&gt;Possible: Yes &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can in theory lift anything. To do this you will simply need to generate an equal or exceeding amount of lift than the weight of the object. You will also need to generate enough thrust to achieve said situation. The closest thing I can think of to this was &lt;a href=&quot;https://en.wikipedia.org/wiki/Hughes_H-4_Hercules&quot; rel=&quot;nofollow&quot;&gt;Howard Hughes Spruce Goose&lt;/a&gt; which did actually fly. If you are talking about the kind of vertical hovering that the ship in the movie does you would need to generate an amazing amount of thrust to achieve that. A US &lt;a href=&quot;https://en.wikipedia.org/wiki/Nimitz-class_aircraft_carrier&quot; rel=&quot;nofollow&quot;&gt;Nimitz-Class aircraft carrier&lt;/a&gt; displaces 100,000 long tons (224,000,000 LBS) so you would need to generate at least that much thrust but in reality you would need to generate more to overcome drag and to actually accelerate the craft vertically. For a point of comparison the &lt;a href=&quot;https://en.wikipedia.org/wiki/Saturn_V&quot; rel=&quot;nofollow&quot;&gt;Saturn V rocket&lt;/a&gt; weighed 3270 tons (6,540,000 pounds).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we work through a quick example (these are very very lose numbers), lets take the Nimitz at 224,000,000LBS and the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow&quot;&gt;GE90 jet engine&lt;/a&gt; (currently the biggest turbo fan jet). The GE90 generates about 115,000 lbf of thrust. So it would take just under 2000 GE90s to generate enough thrust. But lets round it off at 2000 for ease of use and a bit of extra power. The diameter of the engine is 3.429m and the Nimitz is 332.8m long. You would need arms with 10 engines a piece just to make all 2000 engines fit down the length of the side. If they were stacked directly next to each other the arms would be about 35m in length. The bigger issue here is fuel flow/mass. You would need to lift enough fuel to actually power these engines for a useable amount of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the more sifi side of things, you could use the Nimitz's nuclear reactor to power ducted fans which overcomes the fuel problem to an extent but I dont have any numbers on that.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-09T15:01:35.600" LastActivityDate="2015-10-09T15:01:35.600" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="21809" PostTypeId="1" CreationDate="2015-10-09T15:41:55.387" Score="3" ViewCount="4214" Body="&lt;p&gt;For the leading edges of aircraft's flight surfaces, there are a few more common deice and anti-ice methods available. What are the most common systems? What are the alternatives? Is there any research going into alternatives where new technology might provide better or more cost effective solutions?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-09T17:48:39.490" Title="What common forms of deice and anti-ice exist and what future alternatives are being researched?" Tags="&lt;icing&gt;&lt;anti-ice&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21810" PostTypeId="2" ParentId="21711" CreationDate="2015-10-09T16:07:32.530" Score="4" Body="&lt;p&gt;In addition to the systems listed by RedGrittyBrick, it is also possible to let the aircraft detect itself, from its sensors, potential crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This problem has been studied, and is pretty well documented in a report made by the BEA (the French equivalent of the NTSB) after the crash of the flight AF447. The full report is available in &lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/transmission.declenchee.de.donnees.de.vol.pdf&quot; rel=&quot;nofollow&quot;&gt;French&lt;/a&gt; and in &lt;a href=&quot;http://www.bea.aero/en/enquetes/flight.af.447/triggered.transmission.of.flight.data.pdf&quot; rel=&quot;nofollow&quot;&gt;English&lt;/a&gt;. I made a summary of their work in this answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The solution proposed in this report is a triggered transmission of flight data. The aircraft transmits them only if it detects a potentially dangerous situation from its sensors (this reduces the load on communication systems).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two types of triggering criterion are proposed :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;One base on binary logic&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One based on Fuzzy logic&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;They both take into account several parameters (speed, pitch angle, pilot's inputs...) and verify some relations about them. For example, if &lt;code&gt;roll &amp;gt; 50° for more than 2s&lt;/code&gt;, something is probably wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The criterion have been check against a database of real flight data recovered from crashed aircrafts, in order to assess their performances : &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The robustness of the triggering criteria was evaluated using the following metrics:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;False detection rate (or nuisance trigger rate): out of all the normal flights, how many are considered as containing an emergency situation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;Nuisance transmission time that the nuisance triggers generate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;Emergency situation detection rate: out of all the accident/incident flights, how many are considered as containing an emergency situation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;For flights with a correctly detected emergency situation, what is the warning time between the time of detection and the time of impact with the surface&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The conclusion of these tests is that accidents were almost always predicted (binary logic failed in only one case out of 44, fuzzy logic detected every case).  On average, the problem was raised about 350s before the actual crash (the median is around 33s, minimum at 3s and maximum at 10,019s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second half of the report discusses different system to transmit these triggered alarms to infrastructures on the ground. It is also interesting and well written, but outside the scope of this question.&lt;/p&gt;&#xA;" OwnerUserId="6818" LastActivityDate="2015-10-09T16:07:32.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21811" PostTypeId="1" AcceptedAnswerId="21813" CreationDate="2015-10-09T17:13:21.800" Score="1" ViewCount="151" Body="&lt;p&gt;If any modern day aerodynamic scholars by chance  gone through rig vedas of hindu mythology. It has been described like below.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;jumping into space speedily with a craft using fire and water ...&#xA;  containing twelve stamghas (pillars), one wheel, three machines, 300&#xA;  pivots, and 60 instruments.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reference from: &lt;a href=&quot;https://en.wikipedia.org/wiki/Vimana&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Vimana&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any scientifical proofs that those aerodynamic principles would have worked for them or just a myth?&lt;/p&gt;&#xA;" OwnerUserId="11668" LastEditorUserId="11668" LastEditDate="2015-10-09T17:25:48.560" LastActivityDate="2015-10-09T17:40:04.060" Title="Areodynamics of ancient flying machines. Did they really worked for them?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ClosedDate="2015-10-09T19:34:30.017" ContentLicense="CC BY-SA 3.0" />
  <row Id="21812" PostTypeId="2" ParentId="21809" CreationDate="2015-10-09T17:16:50.430" Score="3" Body="&lt;p&gt;This depends on the plane but generally speaking there are, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;De-Ice Boots&lt;/strong&gt; which work by allowing ice to build up and then they are inflated, thus cracking the ice off the leading edge. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/luUWi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/luUWi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(source)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Heated Leading Edge&lt;/strong&gt; Relatively self explanatory but it simply heats the leading edge either electrically or via hot engine bleed air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UmGfr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UmGfr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.quora.com/What-is-aircraft-deicing&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weeping Wing (Chemical)&lt;/strong&gt; is a technique used on some small planes where de-ice fluid is pumped through small holes in the wing leading edge to prevent the ice from building up. This presents 2 separate problems that the other systems don't suffer from. Aside from the weight toll you take for the system its self de-ice fluid is heavy and imparts another useful load toll. You also run the risk of using up all your fluid while in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m749R.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m749R.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://weepingwings.wordpress.com/tag/tks/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has a nice &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch15.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;briefing on it you can find here&lt;/a&gt; which outlines all the various types of systems and the risks that come from icing. Their official list of icing prevention is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Heating surfaces with hot air&lt;/li&gt;&#xA;  &lt;li&gt;Heating by electrical elements&lt;/li&gt;&#xA;  &lt;li&gt;Breaking up ice formations, usually by inflatable boots&lt;/li&gt;&#xA;  &lt;li&gt;Chemical application&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-09T17:24:57.987" LastActivityDate="2015-10-09T17:24:57.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21813" PostTypeId="2" ParentId="21811" CreationDate="2015-10-09T17:31:30.910" Score="5" Body="&lt;p&gt;Just a few points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You are yourself conceding that these are from mythology. If something is from mythology, it is (almost) certainly a myth.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Description of a fictional flying machine and explaining their principles of operation are completely different. To the best of my knowledge, none of these texts even try to explain the principle of operation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Actually, there was a &lt;a href=&quot;http://cgpl.iisc.ernet.in/site/Portals/0/Publications/ReferedJournal/ACriticalStudyOfTheWorkVaimanikaShastra.pdf&quot;&gt;study carried out on one of these texts&lt;/a&gt;, which thoroughly debunked the claims made and concluded,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the planes described above are (at) the best poor concoctions, rather than expressions of something real.None of the planes has properties or capabilities of being flown; the geometries are unimaginably horrendous from the point of view of flying; and the principles of propulsion make then  resist rather than assist flying. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-09T17:40:04.060" LastActivityDate="2015-10-09T17:40:04.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21814" PostTypeId="2" ParentId="21809" CreationDate="2015-10-09T17:39:53.863" Score="3" Body="&lt;p&gt;There are four common forms, and not all are available to all aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Heating the leading edge of all surfaces. This is done either by bleed air or electrically, and both will reduce engine thrust. Due to the high energy demand, electrical heating is mostly used on air intakes or propeller roots.&lt;/li&gt;&#xA;&lt;li&gt;Inflatable rubber boots. They are more economical, but must be operated correctly. If activated too early, the thin ice will not break off, if activated too late, the thick ice will prevent them from inflating.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://books.google.de/books?id=5L-uA7irM14C&amp;amp;pg=PA100&amp;amp;lpg=PA100&amp;amp;dq=Beech%20Starship%20anti-ice&amp;amp;source=bl&amp;amp;ots=RW2ohYGXr2&amp;amp;sig=MaYt9yuj1IcpG12XjXcfsMf6oHU&amp;amp;hl=de&amp;amp;sa=X&amp;amp;ved=0CC8Q6AEwA2oVChMIx8bzvPS1yAIVAsRjCh3NFgOL#v=onepage&amp;amp;q=Beech%20Starship%20anti-ice&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;De-icing fluid&lt;/a&gt;: This requires fine holes in the leading edge through which a de-icing fluid is squeezed to break the bond between ice and structure. Some &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Starship&quot; rel=&quot;nofollow&quot;&gt;Beech Starships&lt;/a&gt; used titanium leading edges with laser-cut holes. Earlier systems, like that on the &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Aerospace_125&quot; rel=&quot;nofollow&quot;&gt;BAe-125&lt;/a&gt;, used sintered metal sheets which had tiny pores.&lt;/li&gt;&#xA;&lt;li&gt;Fly faster: Military jets don't need anti-ice, they use the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stagnation_temperature&quot; rel=&quot;nofollow&quot;&gt;stagnation heat&lt;/a&gt; generated by a higher flight Mach number. Generally, flying Mach 0.9 or above is enough to avoid trouble in light icing conditions.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Concerning future means: &lt;a href=&quot;http://quoteinvestigator.com/2013/10/20/no-predict/&quot; rel=&quot;nofollow&quot;&gt;It is difficult to make predictions, especially about the future&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-09T17:46:14.973" LastActivityDate="2015-10-09T17:46:14.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21815" PostTypeId="2" ParentId="21809" CreationDate="2015-10-09T17:48:39.490" Score="5" Body="&lt;p&gt;In general, deicing (removal of ice after it had formed) and anti icing (prevention of ice formation) methods used are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ki0L4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ki0L4.png&quot; alt=&quot;De-icing and Anti-icing systems&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;GKN Technology: Leading the way toward more efficient aircraft&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Mechanical&lt;/em&gt; which simply pushes the ice off the leading edges. An example is the pneumatic deicing boots, which is the oldest method used where an inflatable rubber boot is used for removing accumulated ice from the leading edges.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KGWYp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KGWYp.jpg&quot; alt=&quot;Pneumatic deicing boots&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: quora.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Deicer_(PSF).png#/media/File:Deicer_(PSF).png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Deicer (PSF)&lt;/a&gt;&quot; by Pearson Scott Foresman - Archives of Pearson Scott Foresman, donated to the Wikimedia Foundation→This file has been extracted from another file: &lt;a href=&quot;//commons.wikimedia.org/wiki/File:PSF_D-240001.png&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;File:PSF D-240001.png&quot;&gt;PSF D-240001.png&lt;/a&gt;.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Heating&lt;/em&gt; In large aircraft, the wing (and tail) leading edges are heated by engine bleed air (electro-thermal heaters in case of Boeing 787) for anti-icing and de-icing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1YBPQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1YBPQ.png&quot; alt=&quot;Anti Icing System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Aircraft Anti-Icing Systems&lt;/em&gt; by Leslie Mehl and Annie Parsons&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Chemical&lt;/em&gt; de-icing systems use dry or liquid chemicals designed to lower the freezing point of water (various salts or brines, alcohols, glycols); or by a combination of these different techniques.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Fluid de-icing systems&lt;/em&gt; which use de-icing fluid from a storage tank and fed through micro-filters to a number of porous metal distributor panels. As the fluid escapes, it breaks the adhesion between the ice and the wing and the airflow carries it away, creating the so called 'weeping wing'&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are a number of other de- and anti- icing methods are also available/under development, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Electro-impulse method&lt;/em&gt; used high-voltage capacitors, which are rapidly&#xA;discharged through the coils installed just inside the skin of the aircraft leading edge, resulting in a electromagnetic repulsive force (on the aircraft skin), throwing ice in all directions. However, the electromagnetic interference and structural fatigue associated with this method limits its application.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Electro- Expulsive Separation System&lt;/em&gt; An electric current runs through parallel layers of flat, copper ribbon. When a large pulse of current is passed, a repelling magnetic field is created, causing the upper conductor to jump less than a twenty-thousandth of an inch. The resulting high acceleration causes the the ice to break into tiny particles that fall from the airplane's surface.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T7D3e.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T7D3e.gif&quot; alt=&quot;Electro Expulsive system in operation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Electro-Expulsive Separation System shatters and ejects ice from a wing model in a wind tunnel test&lt;/em&gt; from ipp.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Electro-Mechanical Expulsion Deicing System&lt;/em&gt;, whose principle of operation is given by the developer as,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A microsecond duration high current electrical pulse delivered to the actuators in timed sequences generates opposing electro-magnetic fields that cause the actuators to change shape rapidly. This change of the actuator shape is transmitted to the erosion shield of the LEA causing it to flex and vibrate at a very high frequency. This rapid motion results in acceleration-based debonding of accumulated ice on the erosion shield.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vIZ0Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vIZ0Z.jpg&quot; alt=&quot;Electro Mechanical Expulsing Deicing system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;An Overview of the Deicing and Antiicing Technologies with prospects for the Future&lt;/em&gt; by Zdobyslaw Goraj&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Ultrasound&lt;/em&gt; Some research is also going on into vibrating the wings using ultrasound to remove ice formed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Shape memory Alloys&lt;/em&gt; have also been proposed to be utilized for deicing and anti icing, with their shape changing properties being used for ice removal when required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VdRFT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VdRFT.jpg&quot; alt=&quot;Shape memory alloy anti-icing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;An Overview of the Deicing and Antiicing Technologies with prospects for the Future&lt;/em&gt; by Zdobyslaw Goraj&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has also been some research into usage of carbon nanotubes for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-09T17:48:39.490" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21816" PostTypeId="1" CreationDate="2015-10-09T18:25:12.350" Score="2" ViewCount="806" Body="&lt;p&gt;How to separate the stability derivatives: $C_{M\dot \alpha}$ and $C_{Mq}$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can imagine a $q=const, \dot \alpha=0$ movement like this&#xA; &lt;a href=&quot;https://i.stack.imgur.com/mbn2m.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mbn2m.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what a $\dot\alpha=const, q=0$ movement would be look like?&lt;/p&gt;&#xA;" OwnerUserId="11676" LastActivityDate="2015-10-09T21:49:12.970" Title="How to calculate the stability derivative of Pitch Moment with respect to AOA rate?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21817" PostTypeId="2" ParentId="21816" CreationDate="2015-10-09T18:50:30.047" Score="2" Body="&lt;p&gt;$q = 0$ means no change of pitch angle. You also have a constant rate change in AoA ($\dot{\alpha} = const$). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between the pitch angle ($\theta$) and AoA ($\alpha$) is the flight path angle ($\gamma$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\theta = \alpha + \gamma$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this it follows that the flight path angle changes opposite to the change of change of AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\dot{\gamma}=-\dot{\alpha}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not a manoeuvre that will happen in real life. An approximation of such a situation can happen when after a brief but strong pull-up the pitch angle is kept constant while the path angle of the aircraft is still increasing. The rate of change of the AoA will not be constant in such a manoeuvre.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="1467" LastEditDate="2015-10-09T19:42:50.383" LastActivityDate="2015-10-09T19:42:50.383" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21818" PostTypeId="2" ParentId="21766" CreationDate="2015-10-09T18:52:58.267" Score="7" Body="&lt;p&gt;For single engine pushers with a canopy, when a pilot bails out of a manned aircraft they might hit the prop or intake at the rear of the aircraft. This requires either special provisions for ejecting, like falling out the bottom or side of the aircraft, or the installation of an ejection seat powerful enough to guarantee the pilot clears the propeller. This all adds weight and cost. A lot of pilots don't like this idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An unmanned drone has no such problem, aircraft designers are free to choose designs without considering how a human will get out of it.&lt;/p&gt;&#xA;" OwnerUserId="1444" LastActivityDate="2015-10-09T18:52:58.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21819" PostTypeId="2" ParentId="21816" CreationDate="2015-10-09T21:49:12.970" Score="2" Body="&lt;p&gt;If you add wind (a gust), the sought-after situation would be flying into a vertical gust. If the vertical wind speed changes linearly with the distance flown and the aircraft has sufficient inertia and/or low static stability, you get no pitch movement and a constant angle-of-attack rate, albeit only for a short time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-09T21:49:12.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21820" PostTypeId="1" AcceptedAnswerId="21831" CreationDate="2015-10-09T22:33:13.277" Score="6" ViewCount="17293" Body="&lt;p&gt;When Boeing introduced the 747-100 in 1969, its &lt;a href=&quot;http://www.flugzeuginfo.net/acdata_php/acdata_7471_en.php&quot;&gt;maximum ceiling was 45,100 feet&lt;/a&gt;; half a century later, when Boeing introduced the 777x, its &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777X#Specifications&quot;&gt;maximum ceiling was 43,100 feet.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, the maximum ceiling of the Airbus A300, introduced in 1972, is &lt;a href=&quot;http://www.flugzeuginfo.net/acdata_php/acdata_a300_en.php&quot;&gt;40,000 feet&lt;/a&gt;, while the ceiling of the A350, introduced 2 years ago, is &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A350_XWB#Specifications&quot;&gt;43,100 feet&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the all the other advances in aircraft design between the past and current generation of airliners, why has the ceiling remained unchanged?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="167" LastEditDate="2015-10-09T23:58:49.617" LastActivityDate="2015-10-10T04:51:29.080" Title="Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years?" Tags="&lt;aircraft-design&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ClosedDate="2015-10-10T06:58:26.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="21821" PostTypeId="1" CreationDate="2015-10-09T22:50:10.463" Score="4" ViewCount="344" Body="&lt;p&gt;In &lt;a href=&quot;http://wrightbrothers.altervista.org/Wrights/WB_various_doc/1903-06-18--Letter-W-Wright-to-O-Chanute--Dayton-Ohio-pp-1-4.pdf&quot; rel=&quot;nofollow&quot;&gt;a letter written by Wilbur Wright and addressed to Octave Chanute, dated 1903/06/18&lt;/a&gt;, I have found two things that I do not quite understand.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Our engine develops at the brake 15.6 horse power and we are convinced that this is very close to what we will be able to reach as a maximum. It furnishes in foot pounds at the brake, energy equivalent to 23 percent of the heat units&#xA;  contained in the fuel, so its efficiency is some twenty percent higher than the usual efficiency of gasoline engines which ranges from 14 to 18 percent of the total power contained in the fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How did the two brothers make such a revolutionary improvement?&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Engine_efficiency&quot; rel=&quot;nofollow&quot;&gt;Modern gasoline engines have a maximum thermal efficiency of about 25% to 30%&lt;/a&gt;. The Wright brother's motor had an efficiency of 23% in 1903.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Dumont motor may develop more than 10 horsepower but it is with me a case of seeing before believing. The screw of the airship was 4 meters in diameter and had a pitch of 4 meters, and the engine at 1200 revolutions (which is the speed of maximum power of motors of this size) drove it 200 turns per minute and gave a thrust of 154 to 165 lbs. Now if you multiply the thrust, by the pitch divided by the circumference of the screw, and multiply this by the travel per minute of the center of pressure (which is about 5/6 of the circumference of the screw) you will find that the result is about 10 horse power.” &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is evident that the Wrights used the relation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Power = Thrust x (5/6) x pitch x (RPM/60 sec)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where does this formula come from?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly is that &quot;&lt;em&gt;center of pressure (which is about 5/6 of the circumference of the screw)&lt;/em&gt;&quot;?&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-10T12:35:29.687" LastActivityDate="2015-10-10T12:35:29.687" Title="How did Wilbur Wright create and use the formulas he mentions in his letter to Octave Chanute?" Tags="&lt;propeller&gt;&lt;aviation-history&gt;&lt;propulsion&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21822" PostTypeId="2" ParentId="21820" CreationDate="2015-10-09T23:17:36.460" Score="6" Body="&lt;p&gt;The aircraft are optimized to fly at a particular altitude, which has not changed over the years. There are multiple reasons for this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The higher you go, the less denser air becomes; So, for flying at higher altitude (i.e. for same lift), the aircraft has to fly at higher angle of attack (increasing drag; the wing will stall at some altitude anyway) or greater speed (requiring more thrust due to increased drag).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the altitude increases, the thrust produced by the engine falls, and at some point, the thrust produced isn't just enough for flight. This is the most important limitation for service ceiling.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In commercial airliners, the cabin pressure altitude is held constant (usually ~8000 ft ISA) and the differential pressure will cause stresses on the fuselage; As the air density decreases with altitude, this stress increases and strengthening the structure will increase weight, resulting in poor performance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of transport aircraft, the service ceiling may sometimes be limited by the maximum altitude from which they can descend to 14,000 ft in less than a specified time (4 min). Commercial airliners are usually limited by this certification altitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even if the engine thrust is increased and the aircraft can fly at higher altitudes (at more speed), at some point another limitation will manifest itself- The air being accelerated over the wing will reach supersonic speeds and form shock waves, leading to a paradoxical situation where you can neither increase the speed (which will increase drag due to shock waves) nor decrease speed (which will stall the aircraft).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, some aircraft have flown at higher altitudes where their design was  optimal. For example, Concorde flew at ~55,000 ft due to lower drag and consequential heating of the airframe from supersonic speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an interesting (and unrelated) side note, any aircraft, however powerful, cannot fly above certain altitude as the atmosphere becomes too thin and it would have to fly faster than orbital velocity to generate necessary lift. This is taken as the point where outer space begins and is called the &lt;a href=&quot;https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line&quot;&gt;Kármán line&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-10T00:15:39.583" LastActivityDate="2015-10-10T00:15:39.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21823" PostTypeId="1" CreationDate="2015-10-09T23:43:39.830" Score="2" ViewCount="947" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OsbGs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OsbGs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Image source &lt;a href=&quot;http://www.datwiki.net/images2/Symmetrical-Airfoil.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;datawiki.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this to slow down airspeed. I know that the high pressure and low pressure above and below the wing both contribute to downwash, but how does this airfoil form downwash?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="5517" LastEditDate="2015-10-12T13:48:25.393" LastActivityDate="2015-10-12T13:48:25.393" Title="Why is this airfoil curved upwards on the bottom part of the airfoil?" Tags="&lt;lift&gt;&lt;airfoil&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21824" PostTypeId="2" ParentId="21775" CreationDate="2015-10-09T23:44:40.727" Score="11" Body="&lt;p&gt;The YF-23 lost the &lt;a href=&quot;https://en.wikipedia.org/wiki/Advanced_Tactical_Fighter&quot;&gt;Advanced Tactical Fighter&lt;/a&gt; program to the YF-22, however it has not been made public why. The ATF evaluation is still classified and details about the YF-23's performance are not easy to come by. They are both excellent aircraft, performed similarly, and there is much speculation why the YF-22 won.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/f-23.htm&quot;&gt;Global Security states that&lt;/a&gt;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to the Air Force, factors in the selection for production of the F-22 were a better designed for maintainability, greater potential for future development, and slightly lower cost. Secretary of the Air Force Donald B. Rice stated that the choice was based on confidence in the ability of the Lockheed team and Pratt &amp;amp; Whitney to produce the aircraft and its engine at projected costs. Emphasizing the importance of the Lockheed team's management and production plans, he denied that either prototype was significantly more maneuverable or stealthy. A popular view is that the decision reflected a preference for maneuverability over stealth &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23#Possible_revival&quot;&gt;A derivative of the YF-23 was proposed&lt;/a&gt; for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Next-Generation_Bomber&quot;&gt;2018 Bomber&lt;/a&gt;, but that idea died when the program was cancelled in 2006.&lt;/p&gt;&#xA;" OwnerUserId="1444" LastEditorUserId="1444" LastEditDate="2015-10-09T23:51:19.907" LastActivityDate="2015-10-09T23:51:19.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21825" PostTypeId="2" ParentId="21823" CreationDate="2015-10-09T23:56:21.163" Score="7" Body="&lt;p&gt;Downwash is simply the deflection of air due to airfoil (or wing etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Symmetric airfoils don't produce downwash (or lift) at zero angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ztMCG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ztMCG.png&quot; alt=&quot;Airfoil Zero angle of attack&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: oppositelock.kinja.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as the angle of attack is increased, the (symmetric) airfoil produces both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4IplN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4IplN.jpg&quot; alt=&quot;Airfoil positive angle of attakc&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;em&gt;Effect of angle of attack on flow field and body forces&lt;/em&gt; by Paul Nathan from youtube.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Symmetrical airfoils are used in rotary wing applications, vertical tail (and rudder) etc.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-10T10:49:41.863" LastActivityDate="2015-10-10T10:49:41.863" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21826" PostTypeId="2" ParentId="21788" CreationDate="2015-10-10T00:50:15.570" Score="4" Body="&lt;p&gt;From page AIRPORT-3 (page 3 overall) of &lt;a href=&quot;http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/intro-USA.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Jeppesen legend&lt;/a&gt; (site jump-off page &lt;a href=&quot;http://ww1.jeppesen.com/aviation/business/additional-info-ifr-paper-services.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1fiOX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1fiOX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-10-10T00:50:15.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21827" PostTypeId="2" ParentId="21775" CreationDate="2015-10-10T01:28:42.150" Score="8" Body="&lt;p&gt;The Advanced Tactical Fighter (ATF) competition was different than some of the other fighter competitions.  The planes never squared off in any kind of mock combat.  The pilots who flew the YF-22 never flew the YF-23 so there was no way to directly compare the 2 in that way.  The competition focused on whether or not the planes met the requirements.  Both aircraft met the requirements so the decision is said to have come down to assessments of the ability of the competing contractors to deliver the aircraft.  Northrop was busy with the B-2 and the YF-22 was thought to be more fully developed and more ready to turn into the F-22.  &lt;a href=&quot;https://www.youtube.com/watch?v=Vpkv1ErWIf8&quot;&gt;Some have claimed&lt;/a&gt; that Lockheed made a better sales pitch.  It should be noted that the YF-23 could carry 4 AMRAAM internally while the YF-22 could carry 6, which may have factored into the Air Force decision.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-10-10T01:28:42.150" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21828" PostTypeId="1" AcceptedAnswerId="21830" CreationDate="2015-10-10T01:35:15.267" Score="6" ViewCount="616" Body="&lt;p&gt;Flying from KPRB to KKIC, in a straight route shown on &lt;a href=&quot;https://skyvector.com/?ll=36.00822843917754,-120.98515319461453&amp;amp;chart=301&amp;amp;zoom=3&amp;amp;fpl=%20KPRB%20undefined%20KKIC&quot; rel=&quot;nofollow&quot;&gt;SkyVector&lt;/a&gt;, except keeping slightly to the East of R-2504A&amp;amp;B, holding an altitude of 3500MSL, except for normal takeoff and descent rates, am I correct in the following?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Taking off from KPRB, you're in Class E airspace within the dashed magenta lines.&lt;/li&gt;&#xA;&lt;li&gt;Once you're out of KPRB's dashed magenta lines, all the way to landing at KKIC, you're in Class G airspace.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm watching a video from &lt;a href=&quot;https://www.youtube.com/watch?v=msfxcx3vUsc&amp;amp;index=2&amp;amp;list=PLPT_UgYDSwmeLFNALMNa0UDSq7F4wi0JV&quot; rel=&quot;nofollow&quot;&gt;PilotEdge&lt;/a&gt;, and at 47:33 he roughly says &quot;We know we're going to be in Echo as we take off.  We're going to be in Echo for the rest.  We know we're in Echo by default, because there's nothing else around.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the &quot;We're going to be in Echo for the rest&quot; part is wrong.  Am I correct here?  If I'm wrong, can you please explain why it's Class E?  It's not within a fuzzy blue or magenta line, and we're flying at 3500MSL, so obviously never going above the Class G 14500AGL ceiling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think he's just simplifying things because in another video said VFR pilots in the air can practically treat all Class G airspace as Class E, not using the less restrictive weather minimums, and be safer.  But, starting to learn aeronautical charts and flight planning, I want to know if I'm fundamentally starting with a misunderstanding or not.  The YouTube video has no comments about this statement.&lt;/p&gt;&#xA;" OwnerUserId="10052" LastEditorUserId="10052" LastEditDate="2015-10-10T03:51:14.367" LastActivityDate="2015-10-10T16:52:37.950" Title="Is airspace above KKIC class G at 3,500’ MSL?" Tags="&lt;class-e-airspace&gt;&lt;class-g-airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21829" PostTypeId="2" ParentId="21828" CreationDate="2015-10-10T03:39:52.373" Score="3" Body="&lt;p&gt;The whole flight is in Class E airspace once above 1,200 FT AGL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is that the Blue shaded line is so hard to find. It's easier to find Class G airspace upto 14,5000 FT MSL on a IFR low enroute chart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this excerpt from Skyvector.  Notice the brown shaded area.  Click on the Phoenix sectional and see the blue shaded line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skyvector.com/?ll=33.2676277850092,-115.22790527580197&amp;amp;chart=302&amp;amp;zoom=2&amp;amp;fpl=undefined&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://skyvector.com/?ll=33.2676277850092,-115.22790527580197&amp;amp;chart=302&amp;amp;zoom=2&amp;amp;fpl=undefined&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6G59j.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6G59j.png&quot; alt=&quot;IFR Low Enroute chart showing Class G airspace&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/FTp4V.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FTp4V.jpg&quot; alt=&quot;VFR Sectional chart showing Class G airspace&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2015-10-10T16:52:37.950" LastActivityDate="2015-10-10T16:52:37.950" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21830" PostTypeId="2" ParentId="21828" CreationDate="2015-10-10T03:48:29.913" Score="5" Body="&lt;p&gt;As long as the flight climbs above 1,200’ AGL before exiting the area where class E begins at the surface, the whole flight is conducted in class E airspace until descending below 1,200’ AGL on the approach to the KKIC airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point of confusion I think is where you've read that class G airspace goes up to 14,500 MSL.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class G Airspace within the United States extends up to 14,500’ MSL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But first you must consider the following.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class E Airspace exists at 1,200’ AGL unless designated otherwise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We can see to the west that there are areas where there are exceptions to the 1,200’ AGL specification, but this flight plan does not go through them. This means that the en route phase of the flight, if conducted above 1,200’ AGL is conducted in class E airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can reference all this using the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-10T14:00:04.907" LastActivityDate="2015-10-10T14:00:04.907" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21831" PostTypeId="2" ParentId="21820" CreationDate="2015-10-10T04:51:29.080" Score="12" Body="&lt;p&gt;Mainly, the optimum cruise altitude is where thrust and lift requirements for both take-off and cruise balance well. An additional benefit is the colder air which increases the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;efficiency of heat engines&lt;/a&gt;. Since this helpful drop in temperature ceases once the aircraft climbs above the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tropopause&quot; rel=&quot;nofollow noreferrer&quot;&gt;tropopause&lt;/a&gt;, the benefits of flying higher increase most below the tropopause.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With increasing flight altitude, the airliner needs:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Bigger engines to create the needed thrust in thinner air&lt;/li&gt;&#xA;&lt;li&gt;Bigger wings to create the needed lift&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With the wings, the size of the tailplanes will also grow; this effect alone likely will weigh more than the beefing up of the fuselage structure for the increased cabin pressure. Flying higher will make almost all parts bigger and heavier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85/11948#11948&quot;&gt;Mach 0.85 is a hard limit&lt;/a&gt; for efficient flight; airliners cannot compensate for lower density by flying faster. The only way to allow higher flight levels is to attach bigger wings and tails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another consideration is Breguet's formula: Jet aircraft have their &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;optimum cruise lift coefficient&lt;/a&gt; at a value of $c_L = \sqrt{0.6\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}$, if we assume the thrust of high-bypass-ratio engines to vary with speed proportional to $v^{-0.5}$, which is a reasonable assumption. This means the airliner cannot fly higher by flying at a higher lift coefficient: This would decrease efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Nomenclature: $c_{D0}$ = zero-lift drag, $AR$ = wing aspect ratio, $\epsilon$ = span efficiency)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the wing size and the engines needed for flight at Mach 0.82 in the tropopause (Mach 0.85 is really not as efficient; follow &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85/11948#11948&quot;&gt;the link&lt;/a&gt; to find out why this is the quoted cruise speed for long-range airliners), the take-off distance is quite reasonable and approximately matches the airports which had been defined by NATO during the cold war. Flying any higher into the stratosphere would increase the aircraft's mass due to bigger engines and wings, but would not incur the efficiency gains of increasing cruise altitude in the troposphere, where temperature drops with altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, picking a lower design cruise altitude would allow to make both wings and engines smaller, but this would translate into:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Higher take-off and landing speeds, and critical speeds during take-off due to the smaller wing,&lt;/li&gt;&#xA;&lt;li&gt;Lower take-off acceleration due to smaller engines,&lt;/li&gt;&#xA;&lt;li&gt;For twins: Not enough thrust during take-off when one engine fails,&lt;/li&gt;&#xA;&lt;li&gt;Lower climb speeds, so it would take longer to reach cruise altitude, and&lt;/li&gt;&#xA;&lt;li&gt;Not fully taking advantage of the cold air up in the tropopause.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Designing for a lower cruise altitude would translate into much longer runways and less efficient flight overall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Designing for cruise in the tropopause is simply the sweet spot for airliner designers where all conditions match well and produce a balanced outcome.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-10T04:51:29.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21832" PostTypeId="1" AcceptedAnswerId="21851" CreationDate="2015-10-10T05:04:23.150" Score="1" ViewCount="191" Body="&lt;p&gt;Do any aircraft have a device which can be pre-set or can be controlled from the ground in order to prevent the aircraft from exceeding a speed limit? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These could be similar to what they have for buses in many places so the bus driver can't go beyond a speed limit.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="167" LastEditDate="2015-10-10T05:43:20.463" LastActivityDate="2015-10-10T23:21:17.933" Title="Are there technical means to enforce aircraft speed limits as well as regulatory means?" Tags="&lt;aircraft-design&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21833" PostTypeId="1" AcceptedAnswerId="21834" CreationDate="2015-10-10T06:29:47.547" Score="10" ViewCount="2207" Body="&lt;p&gt;I know there are VTOL craft meant to take off and land with a vertical trajectory. But, under the perfect wind conditions, could a normal airplane ever land (safely) with a vertical or nearly vertical trajectory?&lt;/p&gt;&#xA;" OwnerUserId="6759" LastEditorUserId="595" LastEditDate="2015-10-10T07:06:38.370" LastActivityDate="2015-10-13T20:44:20.560" Title="Could a plane land vertically in a strong headwind?" Tags="&lt;wind&gt;&lt;vtol&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21834" PostTypeId="2" ParentId="21833" CreationDate="2015-10-10T06:53:51.380" Score="14" Body="&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that you do not have a good understanding of aerodynamics.  I apologise if that is not the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way to think about these sort of questions is to ask &quot;does the aircraft know that it's moving in relation to the Earth&quot;.  The answer to this is &quot;no&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing that matters, and the only thing that the aircraft cares about is airflow (wind) over the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ignore all sorts of little side effects and imagine an aircraft needs 70 kph of wind over the wings to generate lift and stay afloat, straight and level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, imagine the aircraft is flying along and you could somehow make the Earth disappear but leave behind gravity and the atmosphere.  What would happen to the plane?  Nothing!  It still has 70 kph of wind over the wings and it keeps flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now put the Earth back.  It still keeps flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot reduces the power to 69 kph (&quot;thrust X&quot;), the force generated by lift pushing the aircraft up is a little less than that generated by gravity pulling the aircraft down and the craft will start to descend.  Eventually, it will land (assuming that you remembered to put the Earth back!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So two scenarios.  First, one where the air is perfectly still and the thrust from the engine (&quot;thrust Y&quot;) is pushing the aircraft forward at 70 kph.  Second, where the wind is blowing at 70 kph and thrust Y is such that the &lt;a href=&quot;https://www.youtube.com/watch?v=2B65Rgp2PnM&quot; rel=&quot;noreferrer&quot;&gt;aircraft is stationary with respect to the Earth&lt;/a&gt;.  Again, the aircraft does not know, or care, that it is stationary with respect to the Earth, just that it has 70 kph of wind over the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modify the second scenario slightly so that the wind is now 69 kph. The aircraft moves forward at 1 kph. Again, the aircraft does not know, or care, that it is going fowards with respect to the Earth. The wind over the wings is still 70 kph (speed of wind, 69, plus speed of aircraft 1). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reduce the thrust to X again and the aircraft will start to descend, and also become stationary.  Eventually, it will land with no forward or backward speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, this would be almost impossible since the wind is never of a constant speed from a constant direction so little movements would always be taking place.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen a video, which I can no longer find, of a bi-plane which took off into a strong wind, flew backwards down the runway and landed on a spot before the one it took off from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=yzqkSx9d1_8&quot; rel=&quot;noreferrer&quot;&gt;This comes very close&lt;/a&gt;.  With just a little more wind, a vertical landing would have been possible.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-10-13T20:44:20.560" LastActivityDate="2015-10-13T20:44:20.560" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21835" PostTypeId="2" ParentId="21832" CreationDate="2015-10-10T07:34:09.440" Score="0" Body="&lt;p&gt;Short answer, no.&lt;br&gt;&#xA;Speed control is somewhat more complicated in an aircraft. Surely it would be technically possible to install a device that would limit engine power, but it cannot control speed.&lt;br&gt;&#xA;Once airborne, you can always increase speed by pitching the nose down or decrease speed by pitching up. Similar effect can alter speed when flying through strong up- or downdrafts while maintaining level flight.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-10-10T07:34:09.440" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21836" PostTypeId="1" AcceptedAnswerId="21841" CreationDate="2015-10-10T07:37:12.783" Score="11" ViewCount="6067" Body="&lt;p&gt;Can a fighter jet travelling at fast speed be brought down by a weapon like an M134 Minigun or any machine gun?&lt;/p&gt;&#xA;" OwnerUserId="11683" LastEditorUserId="1467" LastEditDate="2018-01-23T09:19:36.717" LastActivityDate="2018-06-28T05:05:30.617" Title="Can a fighter jet be hit by guns?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;jet&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21837" PostTypeId="2" ParentId="21836" CreationDate="2015-10-10T07:58:06.500" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/List_of_aviation_shootdowns_and_accidents_during_the_Iraq_War#Summary_per_type&quot; rel=&quot;nofollow&quot;&gt;Records&lt;/a&gt; suggest that jet fighters are not brought down by hand-aimed bullet-firing weapons.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-10-10T08:04:16.087" LastActivityDate="2015-10-10T08:04:16.087" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21838" PostTypeId="2" ParentId="21836" CreationDate="2015-10-10T08:12:34.727" Score="2" Body="&lt;p&gt;During the Falklands War the British naval ships came under close attack by Argentine Mirage III jets. The ships' crews would fire any weapons they could into the air to create a curtain of fire that the attacking jets had to fly through. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The attackers typically flew lower than fifty feet to avoid radar, so they were definitely in range. In fact, they were so low on the flight across the South Atlantic that their visibility was hampered by spray flying up off the waves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reputedly, at least one aircraft was brought down this way, but I haven't yet found confirmation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, it's perfectly possible that with enough lead or a lucky shot one could hit some vital component (like the pilot) and garner a kill.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-10T08:20:44.307" LastActivityDate="2015-10-10T08:20:44.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21839" PostTypeId="2" ParentId="21836" CreationDate="2015-10-10T08:54:46.643" Score="9" Body="&lt;p&gt;&lt;em&gt;Can a fighter jet traveling at fast speed be brought down by a weapon like an M134 Minigun? or any machine gun?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are machines guns designed to bring down cruise missiles and jet fighters but they look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fx4de.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fx4de.jpg&quot; alt=&quot;Phalanx CIWS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;see: &lt;a href=&quot;https://en.wikipedia.org/wiki/Phalanx_CIWS&quot; rel=&quot;noreferrer&quot;&gt;The Phalanx CIWS close-in weapon system for defense against anti-ship missiles.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-10T08:54:46.643" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21840" PostTypeId="2" ParentId="21833" CreationDate="2015-10-10T09:14:19.233" Score="14" Body="&lt;p&gt;&lt;em&gt;Under the perfect wind conditions, could a normal airplane ever land (safely) with a vertical or nearly vertical trajectory?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, watch this video: &lt;a href=&quot;https://www.youtube.com/watch?v=f7u1jzjFL8s&quot;&gt;Alaska Super Cub, 10 foot landing, 10 foot take off&lt;/a&gt;. Had the wind been a bit stronger the plane would have landed at a null horizontal speed.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-10T09:14:19.233" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21841" PostTypeId="2" ParentId="21836" CreationDate="2015-10-10T09:19:25.143" Score="14" Body="&lt;p&gt;They're called &lt;a href=&quot;https://en.wikipedia.org/wiki/Self-propelled_anti-aircraft_weapon&quot; rel=&quot;noreferrer&quot;&gt;SPAAG's&lt;/a&gt; -- Self Propelled Anti-Aircraft Guns. Older systems tended to fire 23 mm shells. Newer systems tend to fire 30 mm shells augmented by short range missiles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are equipped with radars and high-speed elevation and traverse motors for the turreted guns, so they can react quickly to fast a/c flying low ahead. They're also useful against attack helicopters, which also hug the ground (see below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are &lt;em&gt;short range&lt;/em&gt; weapon systems, typically only effective under 10,000 ft, the guns at much less than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're still useful even today. Medium and long-range SAM's have forced a/c to fly low, below their search and fire control radars, but within range of the guns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was standard NATO doctrine during the late Cold War---&lt;code&gt;low level penetration&lt;/code&gt;---and gave rise to the F-111 (for example), which was designed to fly fast and low, hugging the bumpy terrain of Central Europe. This would have worked very well had the Soviets not fielded SPAAG's (basically modern AAA) and developed their own MANPADS (shoulder-fired SAM's). Soviet AWACS and look-down shoot-down radar also contributed to the decline of this tactic. These systems denied the use of low-level airspace so effectively that during Desert Storm, the Coalition air forces basically gave up low-level operations within the first week and switched to bombing from medium altitude exclusively (above the reach of AAA and MANPADS). Not even the A-10 with its titanium armor could long survive in that environment. Afterward, they did occasionally venture below 10,000 ft, but typically with special permission and enthusiastic support. Even after the first week, when Iraqi air defenses were ineffective, few a/c still flew below 10,000 ft because the AAA and MANPADS were too numerous to be eliminated entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NATO air forces are getting around this problem by buying stealth fighters, namely the F-35A, which can hide from SAM radars, allowing it to fly at medium/high altitudes, far above MANPADS and AAA. But that's for another question/answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an older Shilka (Vitaly V. Kuzmin - &lt;a href=&quot;http://vitalykuzmin.net/?q=node/306&quot; rel=&quot;noreferrer&quot;&gt;http://vitalykuzmin.net/?q=node/306&lt;/a&gt;):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Pwejp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Pwejp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A later Tunguska (Leonid Dzhepko / Л.П. Джепко):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dtdYP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dtdYP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a modern Pantsir (Vitaly V. Kuzmin - vitalykuzmin.net): &lt;a href=&quot;https://i.stack.imgur.com/sfUUf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sfUUf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(All images taken from their respective wikipedia pages.)&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2017-04-17T01:38:27.930" LastActivityDate="2017-04-17T01:38:27.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21843" PostTypeId="2" ParentId="21821" CreationDate="2015-10-10T10:34:34.580" Score="1" Body="&lt;p&gt;I do not have first-hand knowledge of this formula, so what I write below is speculation. But the Wrights used sound physical reasoning, and I will try do do the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power in physics is the product of force and speed. The formula does indeed contain a force (thrust) and a speed (pitch times rotation speed) if the terms used by Wilbur are interpreted in a certain way. Pitch today is an angle, but I would think Wilbur meant with pitch what is termed distance D in the picture below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LamTT.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LamTT.gif&quot; alt=&quot;Propeller advance ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller advance ratio (picture &lt;a href=&quot;http://content.answcdn.com/main/content/img/McGrawHill/Aviation/f0012-01.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is consistent with his earlier sentence where he gives a length for the term pitch. The term pitch * RPM/60 is actually the flight speed in m/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the term 5/6: I would expect that Wilbur calculated the pitch from the incidence of his propeller. Since the propeller blade needs some angle of attack to produce thrust, the actual distance traveled through air is a little smaller than what Wilbur got. Therefore, I think the term 5/6 accounts for that slippage and had been determined empirically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the revolutionary increase in efficiency: I do not know what engines Wilbur used for comparison, but the low number he cites suggests that he used exceptionally poor specimens . &lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-10T10:34:34.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21844" PostTypeId="1" CreationDate="2015-10-10T12:38:08.823" Score="4" ViewCount="2777" Body="&lt;p&gt;Does every Safety–of–Flight Test (SOFT) include full testing of each and every equipment with the full EMC or is it just a basic quality test for some of the affected systems?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="595" LastEditDate="2015-10-10T12:49:20.310" LastActivityDate="2019-10-05T01:08:40.960" Title="Does every Safety–of–Flight Test (SOFT) include full testing of each and every equipment?" Tags="&lt;flight-testing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21845" PostTypeId="1" CreationDate="2015-10-10T12:58:42.443" Score="14" ViewCount="3910" Body="&lt;p&gt;With the new-age technologies and cutting-edge composite materials etc available currently, is it possible that biplane and triplane designs will make a comeback in the near future?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastActivityDate="2020-05-02T11:59:32.190" Title="Can biplane or triplane designs be revived with modern materials?" Tags="&lt;aircraft-design&gt;&lt;aviation-history&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21846" PostTypeId="2" ParentId="21845" CreationDate="2015-10-10T13:25:08.993" Score="24" Body="&lt;p&gt;Biplanes (and triplanes) became (nearly) extinct not because high strength materials (like composites) were not available, but because they became available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the major reasons for use of biplanes in the early days of aviation was that the materials available were of insufficient strength for the (wing) designs used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major disadvantage of biplanes (or triplanes) is aerodynamic- it produces a lot of drag compared to the monoplane and the wings interfere with each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the biplane was an (aerodynamically) inefficient solution to a structural problem. As higher strength materials like Aluminum became widespread, the biplanes fell out of favor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While they &lt;em&gt;can&lt;/em&gt; be revived, I don't see why someone would do that, except for nostalgia (or some special uses, like aerobatics).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some companies who &lt;a href=&quot;http://www.wacoaircraft.com/about/&quot;&gt;manufacture&lt;/a&gt; or &lt;a href=&quot;http://www.retrotec-ltd.co.uk/&quot;&gt;restore&lt;/a&gt; biplanes, but they usually don't use (modern materials like) composites, though modern avionics are used.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-10T13:25:08.993" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21850" PostTypeId="2" ParentId="21845" CreationDate="2015-10-10T22:00:28.923" Score="19" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Biplanes were the best way to take to the air in the early days because people had not wrapped their minds around the concept of a thick wing. All early aircraft used very thin airfoils, and a biplane produced a very lightweight and strong wing. &lt;a href=&quot;https://aviation.stackexchange.com/questions/19361/why-do-older-airplanes-have-a-wing-on-both-the-top-and-the-bottom-of-the-aircraf/19362#19362&quot;&gt;Materials, by the way, had nothing to do with this, so the use of modern composite materials will not change the situation.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But a biplane does have advantages: If you&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9981/what-special-handling-characteristics-or-techniques-do-biplanes-have/9986?s=2%7C0.0907#9986&quot;&gt;want the fastest possible roll rate&lt;/a&gt;,&lt;/li&gt;&#xA;&lt;li&gt;a compact airframe,&lt;/li&gt;&#xA;&lt;li&gt;want to fly slowly,&lt;/li&gt;&#xA;&lt;li&gt;have little need for payload,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;a biplane will be the right solution. However, as soon as the plane is used to earn revenue by transporting goods or people quickly and efficiently over long distances, the monoplane is by far the better solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contraptions like the Blériot type 67 will never be built again (except maybe for entertainment).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PMIBU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PMIBU.jpg&quot; alt=&quot;Blériot type 67&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blériot type 67 bomber (picture &lt;a href=&quot;http://www.1000aircraftphotos.com/Contributions/BregeriePierre/9589.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the very thin wing airfoils.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, for flying fun an &lt;a href=&quot;https://en.wikipedia.org/wiki/EAA_Biplane&quot; rel=&quot;noreferrer&quot;&gt;EAA Biplane&lt;/a&gt; is hard to beat. And it is super easy to build.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/soqXl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/soqXl.jpg&quot; alt=&quot;EAA Biplane P2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EAA Biplane P2 (picture &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/9/5/4/1300459.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). This design is possible with any aviation-rated materials.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-10T22:16:53.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21851" PostTypeId="2" ParentId="21832" CreationDate="2015-10-10T23:14:39.983" Score="5" Body="&lt;p&gt;Some aircraft have flight envelope protections which, among other things, aim to prevent the aircraft exceeding a predefined maximum airspeed.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;High Speed Protection:&lt;/p&gt;&#xA;&lt;p&gt;Prevents exceeding VMO or MMO by introducing a pitch up load factor demand.&lt;br /&gt;&#xA;The pilot can NOT override the pitch up command.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;- &lt;a href=&quot;http://www.airbusdriver.net/airbus_fltlaws.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirbusDriver.net&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Note that these are structural safety limits, people on the ground cannot use this feature to impose arbitrary speed limits by geographic area, time of day etc.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-10T23:21:17.933" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21852" PostTypeId="1" AcceptedAnswerId="21854" CreationDate="2015-10-10T23:54:48.903" Score="7" ViewCount="181" Body="&lt;p&gt;The following paragraph is from Wikipedia &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airport#Environmental_concerns&quot; rel=&quot;noreferrer&quot;&gt;Airport&lt;/a&gt;&quot; page with no citation.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The construction of airports has been known to change local weather patterns. For example, &lt;strong&gt;because they often flatten out large areas, they can be susceptible to fog in areas where fog rarely forms&lt;/strong&gt;. In addition, they generally replace trees and grass with pavement, they often change drainage patterns in agricultural areas, leading to more flooding, run-off and erosion in the surrounding land&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is that bold statement true&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="1696" LastEditDate="2015-10-11T01:00:57.783" LastActivityDate="2015-10-11T02:52:32.613" Title="Can construction of an airport lead to more foggy weather?" Tags="&lt;airport&gt;&lt;weather&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21854" PostTypeId="2" ParentId="21852" CreationDate="2015-10-11T02:52:32.613" Score="7" Body="&lt;p&gt;The statement is apparently from the &lt;a href=&quot;http://catsr.ite.gmu.edu/SYST460/IntroAirportsWorkbook.pdf&quot;&gt;Introduction to Airports Design and Operations&lt;/a&gt; of &#xA;&lt;a href=&quot;http://catsr.ite.gmu.edu/&quot;&gt;Center for Air Transportation Systems Research&lt;/a&gt; at George Mason University.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One form of fog that is formed in airports usually is radiation (or ground) fog. As the flat open surfaces in airport are prone to cooling overnight due to thermal radiation, the air close to the surface is also cooled to the dew point. This reduces the ability of the air to hold moisture, allowing condensation and fog to occur. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason for the statement may be that open areas in the airport give up their heat much quicker than urban heat islands, which does not have flat surfaces prone to thermal radiation. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-11T02:52:32.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21855" PostTypeId="1" AcceptedAnswerId="21856" CreationDate="2015-10-11T06:32:05.370" Score="3" ViewCount="502" Body="&lt;p&gt;Cockpits are at the front of the airplane, and they have pretty limited visibility. &lt;a href=&quot;https://www.youtube.com/watch?v=NQZzTPd1HJw&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot windows can actually open to help with some of this&lt;/a&gt;. We know that there are a ton of tricks that are done to assist pilots in navigating their aircraft with &lt;a href=&quot;https://aviation.stackexchange.com/questions/3316&quot;&gt;the limited visibility that the cockpit provides&lt;/a&gt;. The A380 has multiple cameras to assist in visibility. On the ground, there are people to assist in taxing the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has there ever been any research into a flight engineer, or pilot flying an airplane with a VR headset?&lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-11T21:34:36.657" Title="Is the aft position the ideal place to fly a large aircraft from?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21856" PostTypeId="2" ParentId="21855" CreationDate="2015-10-11T07:37:39.370" Score="3" Body="&lt;p&gt;The only direction a (fixed wing) aircraft can move using the flight controls  is forward. So, it is the forward visibility that is important. The front of the aircraft is the best place for this purpose. The limited visibility in other cases are reasonably over come by using extra cameras or &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_marshalling&quot; rel=&quot;nofollow noreferrer&quot;&gt;marshalers&lt;/a&gt; and markings in the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Airbus A80, for example, has three cameras, one each in the nose, belly and the tail,which can be viewed in the screen by the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K3r6W.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K3r6W.jpg&quot; alt=&quot;A380 Cameras&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: onemileatatime.boardingarea.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest any aircraft has come to be flown using a VR headset is the  AN/AAQ-37 electro-optical Distributed Aperture System (DAS) which is being used in the Lockheed Martin F-35 Lightning II. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EO/DAS consists of six high resolution Infrared sensors  flush-mounted around the aircraft to afford 360-degree, spherical (4$\pi$ steradian) coverage, basically &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/the-f-35-s-x-ray-vision-is-the-future-of-naval-and-all-1636711504&quot; rel=&quot;nofollow noreferrer&quot;&gt;allowing the pilot to see through the airframe&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kg9Ve.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kg9Ve.png&quot; alt=&quot;DAS location&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: alternathistory.org.ua&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each of these sensors collect data in different directions and the on-board computer 'stitches together' these images (and data from EOTS and Radar) and projects them onto the pilot's Helmet Mounted Display System (HMDS), making it the only modern combat aircraft without a HUD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4kJYs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4kJYs.jpg&quot; alt=&quot;F 35 HMDS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: brucesterling.tumblr.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are issues with using these in a commercial airliner:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They are costly- around $400,000 (&lt;a href=&quot;http://www.ecnmag.com/blog/2015/03/f-35s-helmet-mounted-display-system-will-cost-small-fortune&quot; rel=&quot;nofollow noreferrer&quot;&gt;some reports say ~700,000&lt;/a&gt;) apiece and non-interchangeable; while this (situation awareness) could be priceless in combat scenarios, I don't see commercial airliners shelling out this amount of money to replace a system that works pretty well.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The amount of computing power required is enormous. Reportedly, the DAS system collects about a terabyte of data per hour. For aircraft which fly most of their time in a predetermined altitude and heading, this amount of data flow and computing power is not required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Note that the system is not yet fully operational. There are &lt;a href=&quot;https://www.washingtonpost.com/news/checkpoint/wp/2015/04/01/meet-the-most-fascinating-part-of-the-f-35-the-400000-helmet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;issues with the helmet&lt;/a&gt; like latency, 'green' glow, jittery image, resolution issues etc.- reportedly solved, though some pilots say they &lt;a href=&quot;http://theaviationist.com/2015/07/13/f-35-pilot-about-flight-helmet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;don't use this system very often&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-11T07:37:39.370" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21858" PostTypeId="1" AcceptedAnswerId="21943" CreationDate="2015-10-11T09:06:48.700" Score="7" ViewCount="394" Body="&lt;p&gt;Let's say I'm flying a GA aircraft VFR, and I don't have TCAS or similar. I see another aircraft on a converging course, and it must give way to me. (Suppose it has me on its right.) It doesn't appear to be changing course to avoid, so what should I do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously I shouldn't just wait for us to collide, but at the same time, I don't want to take action that will negate its avoiding action. (e.g. If I climb to avoid, and he climbs to avoid because he was expecting me to hold course, we will both still collide.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question seems to relate mostly to uncontrolled airspace, but I'd appreciate an answer that also covers controlled airspace possibilities.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-10-13T17:40:17.003" Title="What if traffic should give way to me but doesn't appear to be?" Tags="&lt;visual-flight-rules&gt;&lt;see-and-avoid&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21859" PostTypeId="1" AcceptedAnswerId="21872" CreationDate="2015-10-11T09:17:57.383" Score="5" ViewCount="598" Body="&lt;p&gt;In the UK, aerodrome weather information includes not only QNH (the air pressure at mean sea level), but also &lt;em&gt;QFE&lt;/em&gt;, the air pressure at runway level. To arrive at an aerodrome, normally one obtains and sets the altimeter to QFE, so that it reads height above aerodrome level. Then if the circuit (traffic pattern) height is 1000 ft (which it usually is), you just read 1000 ft on the altimeter all the way around the circuit; for a standard overhead join it says 2000 ft; and so on. At any aerodrome the altimeter reads the same thing, because you always set QFE.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard that QFE is not used in the US. Do you just have to work out the circuit height in your head by adding 1000 ft to the published aerodrome level? Or are circuit heights given amsl?&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="62" LastEditDate="2015-10-11T13:01:41.920" LastActivityDate="2015-10-12T08:12:34.130" Title="How do pilots in the US identify the circuit (pattern) height?" Tags="&lt;usa&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2016-02-11T20:09:17.787" ContentLicense="CC BY-SA 3.0" />
  <row Id="21860" PostTypeId="1" AcceptedAnswerId="21875" CreationDate="2015-10-11T09:50:17.650" Score="12" ViewCount="4759" Body="&lt;p&gt;Browsing this website, I found &lt;a href=&quot;https://aviation.stackexchange.com/questions/9890/does-huge-rotating-awacs-radar-affect-flight-characteristics&quot;&gt;this question&lt;/a&gt; dealing with torque due to the huge piece in motion, and its answers also speak of drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotodome is located above the aircraft and at the aft of the aircraft. For me it would have been logical to put this huge mass as closely as possible to the CG for stability reasons. For this aircraft, the CG is located close to the main gear, a little in front of them. When I look at an AWACS, I can see that the rotodome is located well behind the main gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/middle/5/9/7/1471795.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sVzML.jpg&quot; alt=&quot;https://i.stack.imgur.com/sVzML.jpg&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;AWACS image courtesy of &lt;a href=&quot;http://www.airliners.net/photo/Luxembourg---NATO/Boeing-E-3A-Sentry/1471795/&amp;amp;sid=b60b4ba662d71f84930009cf686a3338&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, it seems logical to put the rotodome under the aircraft. Its mission is to observe airspace under the aircraft to detect hostiles flying low enough to avoid detection by ground radar. By mounting the rotodome above the fuselage, the aircraft's wings may disturb the radar mounted above them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This position is also shared with other airborne radar such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Beriev_A-50EI_Mainstay2009.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-50&lt;/a&gt; or the &lt;a href=&quot;http://www.airliners.net/photo/USA---Navy/Grumman-E-2C-Hawkeye/2714903/&amp;amp;sid=50f3dda7c5f8b673b1a254cbf3138be1&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-2C&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="8282" LastEditDate="2019-02-05T14:24:40.163" LastActivityDate="2019-02-05T14:24:40.163" Title="Why is the AWACS' rotodome located at the back and over the aircraft?" Tags="&lt;radar&gt;&lt;cg&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21861" PostTypeId="1" AcceptedAnswerId="21866" CreationDate="2015-10-11T10:29:19.980" Score="67" ViewCount="17511" Body="&lt;p&gt;Has there ever been an airplane where the pilot, or cockpit were not located near the nose of the airplane? &lt;/p&gt;&#xA;" OwnerUserId="11423" LastEditorUserId="97" LastEditDate="2015-10-18T17:47:37.480" LastActivityDate="2015-10-18T17:47:37.480" Title="Has there ever been a plane not controlled from the nose?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;" AnswerCount="14" CommentCount="2" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21862" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T10:44:43.740" Score="79" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_DH.83_Fox_Moth&quot; rel=&quot;noreferrer&quot;&gt;de Havilland DH.83 Fox Moth&lt;/a&gt; put the passenger cabin and engine in front of the pilot&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ek79p.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ek79p.jpg&quot; alt=&quot;de Havilland Fox Moth&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Author: &lt;a href=&quot;https://commons.m.wikimedia.org/wiki/User:RuthAS&quot; rel=&quot;noreferrer&quot;&gt;RuthAS&lt;/a&gt;, source: &lt;a href=&quot;https://commons.m.wikimedia.org/wiki/File:DH.83_Fox_Moth_ZK-AGM_Sywell_05.09.15R.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;, licensed under &lt;a href=&quot;https://creativecommons.org/licenses/by/3.0/&quot; rel=&quot;noreferrer&quot;&gt;Creative Commons Attribution 3.0 Unported licence&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorUserId="2171" LastEditDate="2015-10-13T12:10:41.320" LastActivityDate="2015-10-13T12:10:41.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21863" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T10:49:45.453" Score="48" Body="&lt;p&gt;Most of the (single engined) piston aircraft had the cockpit after the engine, This resulted in the cockpit being aft of the wing, like the Supermarine Spitfire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XpFvp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XpFvp.jpg&quot; alt=&quot;Spitfire&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Ray_Flying_Legends_2005-1.jpg#/media/File:Ray_Flying_Legends_2005-1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Ray Flying Legends 2005-1&lt;/a&gt;&quot; by Original uploader was Bryan Fury75 at fr.wikipedia - Transferred from fr.wikipedia; transferred to Commons by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Padawane&quot; rel=&quot;noreferrer&quot; title=&quot;User:Padawane&quot;&gt;User:Padawane&lt;/a&gt; using CommonsHelper.. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F4U Corsair's cockpit was set so far aft that it caused visibility problems for pilots landing in carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hsKOd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hsKOd.jpg&quot; alt=&quot;F4U Corsair&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-11T10:49:45.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21864" PostTypeId="1" CreationDate="2015-10-11T10:50:18.403" Score="5" ViewCount="1538" Body="&lt;p&gt;Suppose a commercial jetliner (say an Airbus A320 or Boeing 737) were scaled down into  a remote-controlled drone, so that its wingspan were two feet wide. My questions regarding this scale-model are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Would jet engines work if scaled-down to such proportions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Would the wings, tailplane, ailerons, flaps etc. work if exactly scaled down in the same ratio as the fuselage? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) At what velocity should the scale-model taxi in order to take off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) At what speeds should the scale-model fly to achieve stable flight, if the length and breadth of the wings etc. are made correctly to scale? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;5) Is it possible that the flight speed of a scale model of a commercial airliner can be scaled down to the extent that it can realistically be remote-controlled by a person on the ground in a city environment, such as a park?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;6) One of the things I am asking here is: can the plane shown in &lt;a href=&quot;https://www.facebook.com/SubiSureshOfficial/videos/356860991172408/&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt; be genuine? Or is it necessarily a hoax, made with computer graphics?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="11411" LastEditDate="2015-10-11T13:26:05.530" LastActivityDate="2015-10-12T01:37:18.610" Title="What is the minimum speed for a scale-model of a modern commercial aircraft to fly?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21865" PostTypeId="2" ParentId="21858" CreationDate="2015-10-11T11:46:25.363" Score="7" Body="&lt;p&gt;You use your PIC authority and best judgment to do whatever is safest. There are so many possible variables that a single answer isn't possible: aircraft types, closing speed, altitude, airspace, ATC instructions etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously you can't do nothing, as you said, but unless you're a mind reader then you have no way to know what the other pilot will do. Or would do: it's possible that he hasn't seen you at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that, if you have limited time and distance to react then your best bet is probably a vertical movement: aircraft at different altitudes can't collide, and if you're on different headings then you'll pass each other very quickly. Maintaining lateral separation at the same altitude is a lot more difficult, that's why formation flying needs special training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether climbing or diving is best depends on the situation and you have to make that call. The only guidance I ever got from an instructor was about birds: he said their instinct if a collision is imminent is to dive, so you should climb to avoid them. But that won't help much with another aircraft :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-10-11T11:46:25.363" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21866" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T11:52:56.467" Score="62" Body="&lt;p&gt;&lt;strong&gt;NASA added a second cockpit to their Boeing 737-100, located in the forward cabin.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;History is a bit patchy, but I believe this was initially to see if it was possible to fly the plane by camera. This might be required by a supersonic design where windows would be impossible (also known as a 'virtual cockpit'). I understand it has been used for all sort of experiments since then.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NASA 515 is the first B-737 built. First used by Boeing to qualify the 737 for airline service, the prototype 737 has since been heavily modified by NASA. It has two separate cockpits - a conventional B-737 forward cockpit providing operational support and safety backup, and an operational research flight deck positioned behind in what was the aircraft's first-class cabin section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.nasa.gov/centers/langley/news/factsheets/B-737.html&quot; rel=&quot;noreferrer&quot;&gt;full list of projects&lt;/a&gt; involving this aircraft are listed on their website.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rgPrE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rgPrE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Credits: NASA&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ItTp4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ItTp4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Credits: Museum of Flight&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="2171" LastEditDate="2015-10-13T12:24:01.960" LastActivityDate="2015-10-13T12:24:01.960" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21867" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T11:58:25.520" Score="41" Body="&lt;p&gt;Many civil and military aircraft between 1920 and 1950 had their pilot in the center of the aircraft, or further aft. Random selection:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bR82o.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bR82o.jpg&quot; alt=&quot;1922: De Havilland&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;1922: De Havilland &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_DH.37&quot; rel=&quot;noreferrer&quot;&gt;DH37&lt;/a&gt; (&lt;a href=&quot;http://www.edcoatescollection.com/ac1/austu/G-AUAA.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not really aft, but interesting offset from the longitudinal axis:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Rv6uI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rv6uI.jpg&quot; alt=&quot;1938: Blohm and Voss BV 141&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;1938: &lt;a href=&quot;https://en.wikipedia.org/wiki/Blohm_%26_Voss_BV_141&quot; rel=&quot;noreferrer&quot;&gt;Blohm and Voss BV 141&lt;/a&gt; (&lt;a href=&quot;http://nonsei2gm.blogspot.fr/2011/05/los-10-aviones-mas-raros-de-la-segunda.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/W8wZW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/W8wZW.jpg&quot; alt=&quot;1939: SAI Ambrosini SS.4&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;1939: &lt;a href=&quot;https://en.wikipedia.org/wiki/Ambrosini_SS.4&quot; rel=&quot;noreferrer&quot;&gt;SAI Ambrosini SS.4&lt;/a&gt; (&lt;a href=&quot;http://www.aviastar.org/air/italy/ambrosini_ss-4.php&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LaPhd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LaPhd.jpg&quot; alt=&quot;1942: F4U-1&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;1942: &lt;a href=&quot;https://en.wikipedia.org/wiki/Vought_F4U_Corsair&quot; rel=&quot;noreferrer&quot;&gt;F4U-1&lt;/a&gt; (&lt;a href=&quot;https://en.wikipedia.org/wiki/Vought_F4U_Corsair&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/241oU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/241oU.jpg&quot; alt=&quot;1944: Spitfire&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;1944: Spitfire &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire_%28Griffon-powered_variants%29#Mk_XIX_.28Mk_19.29_.28types_389_and_390.29&quot; rel=&quot;noreferrer&quot;&gt;Mk 19&lt;/a&gt; (&lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire_%28Griffon-powered_variants%29&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="2171" LastEditDate="2015-10-13T12:37:37.543" LastActivityDate="2015-10-13T12:37:37.543" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21868" PostTypeId="2" ParentId="21864" CreationDate="2015-10-11T12:42:41.050" Score="6" Body="&lt;p&gt;If you scale down the structure of a modern airplane, it would work nicely. Since volume scales with the third power of length, but area scales with the second power, the wing loading would decrease with the scaling factor. Therefore, the dynamic pressure required to fly would also decrease with the scaling factor, as would all aerodynamic pressures. This means that all stresses within the structure will also come down, so the structural safety margin increases with the scaling factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What scales less nicely are the flow phenomena. The Reynolds number will come down with the 1.5th power of the scaling factor (1 power for the length and 0.5 power for the reduced speed), so the boundary layer would be relatively thicker. This would reduce the maximum lift coefficient and would make the gaps between the high lift devices of the wings (slats, flaps) too small to work properly. A &lt;a href=&quot;https://aviation.stackexchange.com/search?q=Who%20says%20scale%20models%20cannot%20be%20used%20for%20spin%20modeling%3F&quot;&gt;simple logarithmic scaling law&lt;/a&gt; works well only over small changes and can not be applied here. After all, the scaling factor is close to 60. I would guess that the maximum lift coefficient is only half of what it is for the real aircraft, so the take-off speed is reduced by a factor of $\sqrt{0.5\cdot scaling\;factor}$. If the &lt;a href=&quot;http://www.aerospaceweb.org/question/performance/q0088.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;take-off speed&lt;/a&gt; of the original is 260 km/h, the model could take off at maybe 45 or 50 km/h.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is quite a bit lower than the speed of the original aircraft, but still too high to fly it comfortably in a park. A wide open field would be more suitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, the relatively thicker boundary layer means the drag of the scaled aircraft is relatively higher, so the L/D of the aircraft comes down. Unfortunately, the flow inside the scaled gas turbines will also be negatively affected by the Reynolds number, so they will produce little thrust. In all, I am quite sure that the scaled Airbus or Boeing would not be able to accelerate to the required take-off speed since both drag increase and thrust loss due to scaling will make this impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I saved the hardest part for the end. The flow in the tiny hydraulic lines would be thick as honey (but you could increase the hydraulic pressure by the scaling factor before the lines burst!), and scaling all control circuitry would result in electronic components which would cease to work completely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, my answer would be a clear no. It will require a lot of adaptions, and only then a scale model could be made to fly.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-10-11T12:50:16.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21869" PostTypeId="2" ParentId="21860" CreationDate="2015-10-11T13:56:13.197" Score="8" Body="&lt;p&gt;Not all AEW&amp;amp;C control aircraft have a huge radome on top of the fuselage. For example, the Chilean EB-707 'Condor' has the radars mounted on the sides and front.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JkxaW.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JkxaW.jpg&quot; alt=&quot;EB 707&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:EB-707_Condor,_Chilean_Air_Force_(FACh)_v2.jpg#/media/File:EB-707_Condor,_Chilean_Air_Force_(FACh)_v2.jpg&quot;&gt;EB-707 Condor, Chilean Air Force (FACh) v2&lt;/a&gt;&quot; by Hippocamelus - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are multiple considerations in deciding the location of the radome/rotodome in an AWACS aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The AEW platform must be able to fly at high altitude such that the radio horizon remains beyond the range expected for a target flying at low altitude; at the high altitudes of operation, the detection of objects at the expected detection range near ground depends on the target discrimination software, rather than putting radar on the belly as the line of sight of the radar would be the same whether it is above or below fuselage. Also, it will be extremely difficult to position the huge rotodome (~30' dia. in E3) under the fuselage. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The range (which determines the power and coverage requirements of the radar) and coverage (the radar needs to cover 360$^{\circ}$) means that there are three options to mount the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;on a radome on top of the fuselage (like EA-3 sentry), high enough to avoid masking effects of the wing etc. This as the best option, as the range is the same in all directions and it gives 360$^{\circ}$ with a single (rotating) radar, In the rotating Mechanically Scanned Array (MSA) radar used in the beginning, this was the only option and is used in modern AESA too as it eliminates the requirement radars at multiple locations.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dygeZ.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dygeZ.jpg&quot; alt=&quot;Triangular&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;State-of-the-Art in Active Electronically-Steered Array Surveillance Radar: Indian Value Addition&lt;/em&gt; by S. Christopher&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;on conformal antennas on the sides and in front of the aircraft, like EB-707. This reduces drag, but requires atleast four antennae as the side antennae provide only 120$^{\circ}$ coverage each and two more antennae are required in the nose and the tail for covering the remaining portion.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WDHPT.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WDHPT.jpg&quot; alt=&quot;Conformal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;State-of-the-Art in Active Electronically-Steered Array Surveillance Radar: Indian Value Addition&lt;/em&gt; by S. Christopher&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;on dorsal antenna on top of the fuselage (Boeing 737 AEW&amp;amp;C)which gives 150$^{\circ}$ coverage on both sides; this again requires multiple radars. In Boeing 737 AEW&amp;amp;C, there is a radar on top for ensuring 360$^{\circ}$ coverage. Also, this is possible only for modern AESA radars.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PJRqG.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PJRqG.jpg&quot; alt=&quot;Dorsal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;State-of-the-Art in Active Electronically-Steered Array Surveillance Radar: Indian Value Addition&lt;/em&gt; by S. Christopher&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The rotodome itself has a stabilizing influence on the aircraft due to its orientation and location.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One of the most important factors is that mounting the radar outside the aircraft enables the use of existing aircraft with minimal modifications compared to conformal radars. As the number of AEW radar operated is pretty low, this is important as commercial aircraft can be utilized.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The radar systems, sensors, operators and consoles weigh much more than the radar itself and can be located in the front to reduce any effect in the center of gravity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-11T13:56:13.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21870" PostTypeId="1" AcceptedAnswerId="21877" CreationDate="2015-10-11T14:24:23.797" Score="14" ViewCount="3079" Body="&lt;p&gt;I've heard rumors about airplanes being on the horizon with &quot;boomless sonic&quot; technology, or the ability to fly supersonic without creating that hazardous shockwave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be very valuable for business travelers who want to cover populated areas at high speed. These aircraft would presumably be certified to fly at supersonic speeds where it is now forbidden due to the damage of sonic booms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this technology exist? Is anyone on the trail to making this work? Is it even possible?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2017-03-07T13:34:03.357" Title="Is there a boomless sonic technology in any state at this time?" Tags="&lt;aircraft-design&gt;&lt;supersonic&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21871" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T14:30:43.230" Score="10" Body="&lt;p&gt;Cheating a bit: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-24B (a lifting body test craft that helped validate the concept for the space shuttle):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NTCXi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NTCXi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Credit: NASA)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cheating quite a bit more:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-82_Twin_Mustang&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Credit: United States Air Force - Dean, Jack&quot;&gt;F-82 Twin Mustang&lt;/a&gt;:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xmf1s.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xmf1s.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Credit: USAF, Jack Dean.)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;White Knight II:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/o0kDp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o0kDp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Credit: D. Miller. &lt;a href=&quot;http://www.flickr.com/photos/fun_flying/3820887625/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.flickr.com/photos/fun_flying/3820887625/&lt;/a&gt;.)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="2171" LastEditDate="2015-10-13T12:42:55.340" LastActivityDate="2015-10-13T12:42:55.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21872" PostTypeId="2" ParentId="21859" CreationDate="2015-10-11T14:40:07.883" Score="7" Body="&lt;p&gt;The Airport/Facility Directory (AFD) has that info. It lists the Traffic Pattern Altitude (TPA) in both MSL and AGL, as well as circuit direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;QFE is not used in the US. So yes, you have to make the correction for field elevation. For example, an airport at 1200 MSL would have a pattern altitude of 2200 ft. (1000 AGL for props. 1500 AGL for Jets) and would be flown using that altitude on the altimeter.&lt;/p&gt;&#xA;" OwnerUserId="11701" LastEditorUserId="572" LastEditDate="2015-10-12T06:14:19.267" LastActivityDate="2015-10-12T06:14:19.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21875" PostTypeId="2" ParentId="21860" CreationDate="2015-10-11T15:11:03.157" Score="10" Body="&lt;p&gt;It's mounted dorsally in large part because it's simply too large to fit beneath the fuselage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotodome has to be that large because inside is actually a planar array. The radar itself isn't round, nor aerodynamic, so it's wrapped in a smooth fairing that presents the same profile regardless of which direction the array is facing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HHKby.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HHKby.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Caption: &lt;em&gt;The Northrop Grumman AN/APY-1/2 AWACS multi-mode radar inside the E-3D rotodome.&lt;/em&gt; (Credit: Scott Carson. &lt;a href=&quot;https://twitter.com/scottcarson1957/status/510531735700779008/photo/1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Twitter&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airborne radars do &lt;em&gt;not&lt;/em&gt; rotate and can indeed be mounted below the fuselage, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_E-8_Joint_STARS&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-8 JSTARS&lt;/a&gt;' APY-7 (primarily a ground surveillance radar): &#xA;&lt;a href=&quot;https://i.stack.imgur.com/jrEku.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jrEku.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(Credit: USAF. &lt;a href=&quot;http://www.af.mil/News/Photos.aspx?igphoto=2000384126&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pave Mover, an APY-7 prototype:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/lI5xt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lI5xt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(Credit: Daderot. &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Daderot&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cancelled E-10 (planned E-3 Sentry and E-8 JSTARS successor) also had a similar under-nose longitudinal array.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dKwl7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dKwl7.jpg&quot; alt=&quot;E-10 DID&quot;&gt;&lt;/a&gt;&#xA;(Credit: Defense Industry Daily. &lt;a href=&quot;https://www.defenseindustrydaily.com/e10a-shes-dead-jim-03139/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, most larger, non-rotating arrays are mounted dorsally and longitudinally, like the Boeing 737 AEW&amp;amp;C:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/OgoUp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OgoUp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(Credit: Seattle Aviator. &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Seattle_Aviator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Link&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Question:] Moreover, it seems logical to put the rotodome under the aircraft. Its&#xA;  mission is to observe airspace under the aircraft to detect hostiles&#xA;  flying low enough to avoid detection by ground radar. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not exclusively. Low-altitude penetrators aren't the only targets. AWACS is also tasked with finding medium to high altitude aircraft, both watching for enemies (eg firing &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Novator_KS-172&quot; rel=&quot;nofollow noreferrer&quot;&gt;AWCAS killers&lt;/a&gt;&quot;) and keeping track of friendlies.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Question:] By mounting the&#xA;  rotodome above the fuselage, the aircraft's wings may disturb the&#xA;  radar mounted above them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You don't need a lot of depression to observe things at medium to long range. At 30,000 ft, the horizon sits just a few degree below level, and even at 30 miles (which is very close) a low-altitude target is just -10 degrees. There's also a fair bit of clearance between the elevated dome and the fuselage/wings, which reduces how much of the ground is masked (roughly -20 degrees from radar to wingtip). Together, there's probably fairly little that an E-3 wouldn't be able to see. You'd have to be practically underneath it at close range. And then you'd have to deal with the fighter escorts... &lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2018-04-09T01:43:11.473" LastActivityDate="2018-04-09T01:43:11.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21876" PostTypeId="2" ParentId="21766" CreationDate="2015-10-11T15:18:52.250" Score="3" Body="&lt;p&gt;A big part of the reason for the bubble shaped head is reduced drag. The area does hide a parabolic antenna but the could be done with many shapes. This shape is designed to have the smallest flat surface area possible to allow the air to flow smoothly across the front of the aircraft instead of becoming disrupted and turbulent by striking a flat surface. This leads to reduced drag and a longer flight time per gallon of fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cessna's and similar aircraft have a windscreen that is basically a large flat plate for the wind to slam against, and while they work great for seeing through, they actually add quite a bit of drag to the aircraft. The cessna's designed mission, however, makes this acceptable.&lt;/p&gt;&#xA;" OwnerUserId="11704" LastActivityDate="2015-10-11T15:18:52.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21877" PostTypeId="2" ParentId="21870" CreationDate="2015-10-11T15:39:29.810" Score="23" Body="&lt;p&gt;Shock wave is a physical phenomenon and as such is unavoidable. The best we can do is to reduce their intensity and reduce their effects on ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A method to eliminate the shock wave (theoretically) was proposed by &lt;a href=&quot;https://en.wikipedia.org/wiki/Adolf_Busemann&quot; rel=&quot;noreferrer&quot;&gt;Adolf Busemann&lt;/a&gt;. His airframe, called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Busemann&amp;#39;s_Biplane&quot; rel=&quot;noreferrer&quot;&gt;Busemann's Biplane&lt;/a&gt; which consists of two triangular cross-section plates a certain distance apart (so that choking is prevented) with the flat sides parallel to the fluid flow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iAAwB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iAAwB.png&quot; alt=&quot;Busemann&amp;#39;s Biplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Supersonic biplane—A review&lt;/em&gt; by Kazuhiro Kusunose et al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is that the shock waves are formed internally between the two (triangular) 'airfoils' and cancel each other out at design condition, shown in the first case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iwDdx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iwDdx.jpg&quot; alt=&quot;Shock Cancellation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Supersonic biplane—A review&lt;/em&gt; by Kazuhiro Kusunose et al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At off design conditions, shock waves are produced. However, this doesn't produce any lift at zero angle of attack, as is obvious. As &lt;a href=&quot;http://news.mit.edu/2012/supersonic-biplane-0319&quot; rel=&quot;noreferrer&quot;&gt;researchers explain&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the design lacks lift: The two wings create a very narrow channel through which only a limited amount of air can flow. When transitioning to supersonic speeds, the channel ... could essentially “choke,” creating incredible drag. While the design could work beautifully at supersonic speeds, it can’t overcome the drag to reach those speeds. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Research is being carried out to overcome this issue- One method proposed is to &lt;a href=&quot;http://www.ifs.tohoku.ac.jp/edge/publications/ifs-biplane.pdf&quot; rel=&quot;noreferrer&quot;&gt;have the wings 'morph' shapes&lt;/a&gt;- so that they are efficient at all speeds. Another group is working to optimize the shape of the airfoils in Busemann's Biplane so that the shock-wave is reduced at all stages of supersonic flight. However, all these studies are in conceptual stage and no experiments have been carried out so far.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA carried out the &lt;a href=&quot;http://www.nasa.gov/aero/sonic_boom_takes_shape.html&quot; rel=&quot;noreferrer&quot;&gt;Shaped Sonic Boom Demonstration&lt;/a&gt;(SSBD), in which the fuselage of a Northrop -5E was modified (kind of like pelican's beak) so as to change the pattern of shock waves formed in supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gxypu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gxypu.jpg&quot; alt=&quot;Shaped Sonic Boom demonstration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-5E_Shaped_Sonic_Boom_Demonstration_aircraft.jpg#/media/File:F-5E_Shaped_Sonic_Boom_Demonstration_aircraft.jpg&quot; rel=&quot;noreferrer&quot;&gt;F-5E Shaped Sonic Boom Demonstration aircraft&lt;/a&gt;&quot; by NASA/Carla Thomas - &lt;a href=&quot;http://www.dfrc.nasa.gov/Gallery/Photo/SSBD/HTML/EC03-0210-1.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.dfrc.nasa.gov/Gallery/Photo/SSBD/HTML/EC03-0210-1.html&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA reported that the modifications were able to reduce the intensity of the shock wave by a considerable amount, as shown in the image below (the 'flat' pressure line is from the SSB demonstrator).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I6mwy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I6mwy.jpg&quot; alt=&quot;Sonic boom signature&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Quieting the Boom- The Shaped Sonic Boom demonstrator and the Quest for Quiet Supersonic Flight&lt;/em&gt; by NASA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active research is still being carried out by various organizations in this field.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-11T15:45:37.193" LastActivityDate="2015-10-11T15:45:37.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21878" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T16:38:38.790" Score="58" Body="&lt;p&gt;Some of the Gee Bee racing planes are obvious candidates. In fact, in one of them the pilot was &lt;em&gt;right next to the tail&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gee_Bee_Model_R&quot; rel=&quot;noreferrer&quot;&gt;Gee Bee Model R&lt;/a&gt;&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VXvNS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VXvNS.jpg&quot; alt=&quot;Gee Bee Model R&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Image Credit&lt;/em&gt;: Wikimedia Commons&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It needs no guessing that the Gee Bee planes were explicitly attempts at shoving the most powerful engine into the smallest and lightest possible air-frame, with the pilot tucked in somewhere. This philosophy, their handling characteristics, and several serious injuries and deadly accidents meant that the models acquired a reputation for being death traps.&lt;/p&gt;&#xA;" OwnerUserId="11705" LastEditorUserId="2171" LastEditDate="2015-10-13T12:30:13.817" LastActivityDate="2015-10-13T12:30:13.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21879" PostTypeId="2" ParentId="21870" CreationDate="2015-10-11T17:15:37.130" Score="13" Body="&lt;p&gt;Yes, there is this technology already. By using the fact that the speed of sound is proportional to the square root of the air temperature, you can fly at a low supersonic speed at altitude and no shock wave would hit the ground. If the Mach number is low enough, your speed will be subsonic in the air at ground temperature, so the shock waves will dissipate on their way down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z6Ta0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z6Ta0.jpg&quot; alt=&quot;Threshold Mach number&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Graphical explanation of the threshold Mach number (picture &lt;a href=&quot;http://www.airpower.maxwell.af.mil/airchronicles/aureview/1971/jul-aug/roberds.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the speed gain would be low and the whole endeavor not very economical. Once the flight speed is increased such that it is also supersonic at ground conditions, audible shock waves will be hard to avoid. They can be mitigated, but not completely avoided.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-17T19:14:25.793" LastActivityDate="2015-10-17T19:14:25.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21881" PostTypeId="1" AcceptedAnswerId="21889" CreationDate="2015-10-11T19:30:43.953" Score="16" ViewCount="10056" Body="&lt;p&gt;At what point during flight would Concorde go supersonic? Would it climb to cruising altitude first? Does altitude affect the transsonic difficulties (buffet, need for extra thrust, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="3394" LastEditDate="2019-12-10T09:04:24.820" LastActivityDate="2019-12-10T09:04:24.820" Title="At what altitude did Concorde go supersonic?" Tags="&lt;supersonic&gt;&lt;concorde&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21882" PostTypeId="1" AcceptedAnswerId="21883" CreationDate="2015-10-11T20:25:22.560" Score="21" ViewCount="4988" Body="&lt;p&gt;There was a &lt;a href=&quot;https://www.youtube.com/watch?v=Q1nYTUQdG7Y&quot;&gt;video&lt;/a&gt; posted to Reddit of pilots waving back from their commercial jetliners. What followed was a &lt;a href=&quot;https://www.reddit.com/r/videos/comments/3oa2ug/will_pilots_wave_back/cvvlha2&quot;&gt;discussion&lt;/a&gt; of whether or not this was a violation of the sterile cockpit rule. Given that waving back is non-essential communication, is this a violation of the FAA sterile cockpi rule? &lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-10-12T09:37:47.583" Title="If a pilot waves back, does it violate the sterile cockpit rule?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21883" PostTypeId="2" ParentId="21882" CreationDate="2015-10-11T20:56:02.837" Score="33" Body="&lt;p&gt;From &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/dd19266cebdac9db852566ef006d346f!OpenDocument&quot;&gt;rgl.faa.gov&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 121.542&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Flight crewmember duties.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) [I omitted this, it's about noncritical (company) procedures]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b)&#xA;  No flight crewmember may engage in, nor may any pilot in command&#xA;  permit, &lt;strong&gt;any activity during a critical phase of flight which could&#xA;  distract any flight crewmember&lt;/strong&gt; from the performance of his or her&#xA;  duties or which could interfere in any way with the proper conduct of&#xA;  those duties [...] such as [...] engaging in&#xA;  nonessential conversations within the cockpit [...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) For the purposes&#xA;  of this section, critical phases of flight includes all ground&#xA;  operations &lt;strong&gt;involving taxi&lt;/strong&gt;, takeoff and landing, and all other flight&#xA;  operations conducted below 10,000 feet, except cruise flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One could argue that waving could distract the pilot taxiing, so according to the letter of the law, &lt;strong&gt;yes&lt;/strong&gt;, you would violate the rule. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I think in the spirit of the rule it's fine, since it just means that the pilot not taxiing is paying attention to the surroundings as well. Reading between the lines, it basically says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) During critical phases of flight, all crew should focus on flying, not selling cooked cardboard&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Also, don't read the paper with a croissant while asking help with a crossword during said phases.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Critical phases of flight are when you're likely to read the bumper sticker on another jet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't think a quick wave is quite as severe a violation as e.g. reading the paper (or, as the FAA calls it, &lt;em&gt;reading publications not related to the proper conduct of the flight&lt;/em&gt;) during take-off. Compare it with a bus driver waving to a fellow driver or one reading the paper while driving. But then, if you do park your plane in a ditch while trying to wave to your mom, don't be surprised to be held fully liable.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2015-10-12T09:37:47.583" LastActivityDate="2015-10-12T09:37:47.583" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21884" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T21:38:03.640" Score="23" Body="&lt;p&gt;&lt;strong&gt;More classes of aeroplane that meet the brief:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All these are remotely piloted vehicles - the pilot is nowhere near the aeroplane, let alone the nose.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Unmanned Aerial Vehicles (UAV)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FHLja.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FHLja.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;MQ-3 Reaper (Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MQ-9_Reaper_CBP.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, US Government, Public Domain)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a8hpH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a8hpH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;RQ-4 Global Hawk (Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Global_Hawk_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, USAF, public domain)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Target Drones&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gZqjv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gZqjv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;QF-4 Phantom (Source: &lt;a href=&quot;https://flic.kr/p/84XFWa&quot; rel=&quot;noreferrer&quot;&gt;Flickr&lt;/a&gt;, user Theo Van Vliet)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9QDuj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9QDuj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;QF-16 drone (Source: USAF, public domain)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Experimental or research RPV&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nasa crashed a Boeing 720 to investigate the properties of Anti-misting Kerosene (AMK)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/feQxYXHXewY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some years later, a Boeing 727 was crashed into the Mexican desert to investigate cabin forces and survivability&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/oYmaP5OKWBQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorUserId="2171" LastEditDate="2015-10-13T12:41:01.697" LastActivityDate="2015-10-13T12:41:01.697" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21885" PostTypeId="2" ParentId="21861" CreationDate="2015-10-11T22:42:07.917" Score="17" Body="&lt;p&gt;Adding to the excellent existing answers, flipping through my copy of The World's Worst Aircraft (because we've learned putting the pilot anywhere but the nose is a terrible idea), I find some... umm... interesting and unique pilot arrangements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Royal_Aircraft_Factory_B.E.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;B.E.9&lt;/a&gt; placed the pilot behind a large protruding pod where the gunner sat &lt;em&gt;in front of&lt;/em&gt; the propeller. As you can imagine, gunners were not thrilled with this arrangement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N7W23.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N7W23.jpg&quot; alt=&quot;B.E.9&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;Boeing&quot; (actually a US Army design, Boeing just built it) &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_GA-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;GA-2&lt;/a&gt; had the pilot in an armored housing in the middle of and on top of the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6OtdM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6OtdM.jpg&quot; alt=&quot;Boeing GA-2 photo from the Ray Wagner Collection&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Loening_PW-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Loening PW-2&lt;/a&gt; was a &quot;high&quot;-wing monoplane with the pilot sitting under a wing mounted so low they had no forward visibility. And this was a pursuit fighter! That's ok, the pilot could see fine when the poorly attached wing tore itself off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R8Dad.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R8Dad.jpg&quot; alt=&quot;Loening PW-2 photo from the Ray Wagner Collection&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1444" LastActivityDate="2015-10-11T22:42:07.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21887" PostTypeId="1" CreationDate="2015-10-11T23:09:25.933" Score="9" ViewCount="6172" Body="&lt;p&gt;I've noticed that when it comes to non-towered airports, some are in class G airspace and others have class E airspace starting from the surface. At first I thought the airports with class E at the surface might be in that configuration because they have precision approaches, but then I found exceptions where the airport has class G at the surface along with a precision approach. Is there a particular reason some non-towered airports are in class E while other are in class G?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1968" LastEditDate="2015-10-12T04:18:07.530" LastActivityDate="2017-09-01T23:50:29.390" Title="Why do some non-towered airports have class E airspace from the surface up?" Tags="&lt;faa&gt;&lt;airspace&gt;&lt;non-towered-airport&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21888" PostTypeId="1" AcceptedAnswerId="21898" CreationDate="2015-10-11T23:13:20.000" Score="12" ViewCount="13058" Body="&lt;p&gt;Let's say an IFR flight was planned to depart from a non-towered airport with class G airspace extending from the surface to 700 feet AGL. The flight visibility and ceiling both go down to 0. Can the pilot get an IFR clearance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the airport had class E airspace from the surface up it would be in controlled airspace from the ground and I'm positive that an IFR clearance could be issued allowing IFR flight in that class E airspace right from takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of class G airspace from the ground, the airspace is uncontrolled. Could an IFR clearance be issued that allows IFR flight and waives the basic VFR weather minimums for class G airspace?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="572" LastEditDate="2015-10-12T08:22:02.863" LastActivityDate="2020-05-13T23:56:12.013" Title="Can an IFR clearance be issued and flown through IMC in class G airspace?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;airspace&gt;&lt;non-towered-airport&gt;" AnswerCount="7" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21889" PostTypeId="2" ParentId="21881" CreationDate="2015-10-11T23:53:57.643" Score="12" Body="&lt;p&gt;Concorde went supersonic during its climb phase to the cruising altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude at which the Concorde can go supersonic was limited by the regulations. For example, the aircraft was only allowed to go at 400 knots during the climb phase between 6,000 and 32,000 ft; also, the aircraft was allowed to go supersonic only after it has crossed the coastline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the air gets thinner during climb, the Mach number increases for same IAS, reaching around 0.93 at 25,000 ft and 0.95 at 28,000 ft. After this, the afterburners are engaged and autopilot is set to the cruising altitude (~ 60,000 ft). During this climb phase to the cruising altitude, the aircraft goes supersonic, settling at around Mach 2 at over 50,000 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight envelope limitations of Concorde (at one configuration) is shown in this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2cX4g.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2cX4g.jpg&quot; alt=&quot;Concorde limitations&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: pprune.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitude affected the thrust requirements, as more thrust is required for the same speed at lower altitudes due to density. This is one of the reasons for Concorde flying at altitude far above that of subsonic airliners.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-11T23:53:57.643" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21892" PostTypeId="2" ParentId="21861" CreationDate="2015-10-12T00:58:44.977" Score="21" Body="&lt;p&gt;The 1906 plane of Santos-Dumont was controlled from the rear side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V2YqF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V2YqF.jpg&quot; alt=&quot;Alberto Santos-Dumont&amp;#39;s 1906 plane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The plane of Santos Dumont&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-12T01:11:24.603" LastActivityDate="2015-10-12T01:11:24.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21893" PostTypeId="2" ParentId="931" CreationDate="2015-10-12T01:01:37.747" Score="0" Body="&lt;p&gt;For every 1% reduction in fuel weight there is a .75% reduction in fuel burn, &quot;it takes fuel to carry fuel&quot;&lt;/p&gt;&#xA;" OwnerUserId="11716" LastActivityDate="2015-10-12T01:01:37.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21895" PostTypeId="2" ParentId="21888" CreationDate="2015-10-12T01:22:48.370" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's say an IFR flight was planned to depart from a non-towered airport with class G airspace extending from the surface to 700 feet AGL. The flight visibility and ceiling both go down to 0. Can the pilot get an IFR clearance?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.  The ATC clearance will use the words &quot;when entering controlled airspace&quot;...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it legal to takeoff from a Class G airport with less than 1 sm visibility?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't know. Here is an interesting ALJ decision from one pilot who did that.  Although, his specifics are just a little different.  An excerpt from the decision.  &lt;a href=&quot;http://www.ntsb.gov/legal/alj/OnODocuments/Aviation/3935.pdf&quot; rel=&quot;nofollow&quot;&gt;Case 3935&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Respondent has appealed from the oral initial decision&#xA;  issued by Administrative Law Judge Joyce Capps at the close of an&#xA;  evidentiary hearing held in this matter on July 8, 1991. In&#xA;  that decision the law judge found that respondent's takeoff from&#xA;  an uncontrolled airport into clouds without a clearance or&#xA;  release from air traffic control (ATC) was not a violation of 14 C.F.R. 91.155(a), but was in violation of 14 C.F.R. 91.13(a).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="1968" LastEditDate="2015-10-12T03:30:22.263" LastActivityDate="2015-10-12T03:30:22.263" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21897" PostTypeId="1" AcceptedAnswerId="21899" CreationDate="2015-10-12T03:16:29.617" Score="5" ViewCount="790" Body="&lt;p&gt;From the news of &lt;a href=&quot;http://www.channelnewsasia.com/news/singapore/singapore-airlines-plane/2184022.html&quot; rel=&quot;noreferrer&quot;&gt;Singapore Airline A330 nose gear collapse&lt;/a&gt; at Changi, I notice an equipment is under the nose part of aircraft and somewhat damage the radome when nose gear collapse. It looks like some ladder. What is it and what is it used for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: it is during routine airline operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iWv36.jpg&quot; alt=&quot;picture of equipment&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="8730" LastEditDate="2015-10-12T04:47:49.820" LastActivityDate="2015-10-13T07:40:48.847" Title="What is this equipment under nose of aircraft?" Tags="&lt;airline-operations&gt;&lt;equipment&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21898" PostTypeId="2" ParentId="21888" CreationDate="2015-10-12T03:22:38.020" Score="13" Body="&lt;p&gt;The key point is in your last sentence: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the case of class G airspace from the ground, the airspace is uncontrolled.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Uncontrolled airspace is, well, uncontrolled. An appropriately rated, current pilot, in an appropriately equipped aircraft, may fly IFR in class G airspace without either a clearance or a flight plan. There are no clearances to waive VFR minima in class G, because the flight is conducted under IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an entire flight is flown in class G airspace, a pilot does not need to talk to a controller at all. When class G airspace is overlaid by controlled airspace, like class E, the pilot will need a clearance before entering controlled airspace. The controller will provide a clearance (&lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order  7110.65&lt;/a&gt;, p. 4-3-2):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;WHEN ENTERING CONTROLLED AIRSPACE &lt;em&gt;(instruction)&lt;/em&gt;, FLY HEADING &lt;em&gt;(degrees)&lt;/em&gt; UNTIL REACHING &lt;em&gt;(altitude, point, or fix)&lt;/em&gt; BEFORE PROCEEDING ON COURSE.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Once the pilot is released for departure, they would depart IFR in class G, where they would be responsible for their own terrain and traffic clearance (using tools like an &lt;a href=&quot;https://aviation.stackexchange.com/a/21895/136&quot;&gt;Obstacle Departure Procedure&lt;/a&gt;). As soon as they climb into class E airspace, they receive the benefits and responsibilities of flying in the ATC system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An interesting &lt;a href=&quot;http://www.ntsb.gov/legal/alj/OnODocuments/Aviation/3935.pdf&quot; rel=&quot;noreferrer&quot;&gt;border case&lt;/a&gt; is raised &lt;a href=&quot;https://aviation.stackexchange.com/a/21895/136&quot;&gt;by wbeard52&lt;/a&gt;. In this case, a pilot departed a class G airport with class E starting at 700 AGL, and broke out of the clouds before entering controlled airspace. The ruling basically said that taking off in this situation &lt;em&gt;without a clearance&lt;/em&gt; is not explicitly illegal, but falls under &quot;careless or reckless operation&quot; prohibited by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.1.4.7&quot; rel=&quot;noreferrer&quot;&gt;FAR 91.13&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-12T03:22:38.020" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21899" PostTypeId="2" ParentId="21897" CreationDate="2015-10-12T03:36:11.340" Score="7" Body="&lt;p&gt;The report says the aircraft was undergoing a landing gear system check. The equipment looks like a trolley-mounted inspection ladder that could well have been used during such a check.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-12T03:36:11.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21900" PostTypeId="2" ParentId="21887" CreationDate="2015-10-12T03:48:41.533" Score="13" Body="&lt;p&gt;This answer is specific to the United States (heck, I don't know if this is an even an issue elsewhere in the world).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airspace classification actually has nothing to do with whether or not a particular airport has a precision approach. It is based on two factors: communications capability and weather observations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a non-towered airport to have Class E (surface) airspace, ATC must have communications capability with aircraft down to the runway surface. Second, weather observations must be provided by a Federally certificated observer and/or Federally commissioned weather observing system. Reference: &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400.2K_w_Chg1_dtd_7-24-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA JO 7400.2K&lt;/a&gt;, paragraphs 18-1-1 and 18-1-2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one (or both) of these conditions are not satisfied, the surface airspace will be class G with a class E floor of 700 ft. AGL if there is an instrument approach into the airport and 1200 ft. AGL if not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, here's a twist: if the airport has a part-time control tower, the airspace may become Class G when the tower is closed, even if both communication and weather reporting requirements are satisfied. Be sure to check the Chart Supplement (fka A/FD).&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2017-09-01T23:50:29.390" LastActivityDate="2017-09-01T23:50:29.390" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21901" PostTypeId="2" ParentId="21688" CreationDate="2015-10-12T05:05:33.290" Score="34" Body="&lt;p&gt;It is a temperature probe for the preconditioned air (PC air) unit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bleed air is required in order to operate the air conditioning packs on an aircraft*. Thus, either an engine or the auxiliary power unit (APU) must remain running, burning jet fuel.  PC air pumps heated or cooled air into the aircraft and allows the pilot to shut down the engines and APU to conserve fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what the system looks like from the outside:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zqubg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zqubg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A probe (located in the passenger loading bridge) is inserted into the cabin to regulate the air temperature while PC air is hooked up and running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Upon parking, ground crews will typically hook up both ground electrical power and PC air, especially if the aircraft will be parked for any length of time. Since the air hose takes some time to unroll and roll, PC air may not be used if the flight is a &quot;quick turn&quot; and the APU will be left running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;* Except for the Boeing 787, which has a no-bleed system.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2018-07-20T01:06:08.563" LastActivityDate="2018-07-20T01:06:08.563" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="21902" PostTypeId="1" AcceptedAnswerId="21942" CreationDate="2015-10-12T05:31:27.560" Score="7" ViewCount="11671" Body="&lt;p&gt;I have some understanding on g-force. But never come across how much g-force acts on a passenger who is traveling in a plane, especially when taking off.&lt;/p&gt;&#xA;" OwnerUserId="11668" LastEditorUserId="1696" LastEditDate="2015-10-13T17:51:23.033" LastActivityDate="2015-10-13T17:51:23.033" Title="What level of G-force does our body experience when we are traveling in a passenger plane?" Tags="&lt;g-forces&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21903" PostTypeId="1" AcceptedAnswerId="21911" CreationDate="2015-10-12T06:18:09.963" Score="2" ViewCount="1009" Body="&lt;p&gt;I was going through Helios crash and learned that Boeing was blamed for having similar sounding alarms for different alarm conditions. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On a given aircraft, can two different warning alarms have the same sound?&lt;/li&gt;&#xA;&lt;li&gt;If so, what other aircraft have the same sound for different kinds of alarms?&lt;/li&gt;&#xA;&lt;li&gt;Has Boeing changed their alarm systems post that incident?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="5517" LastEditDate="2015-10-12T16:44:52.237" LastActivityDate="2015-10-12T17:57:47.860" Title="Do aircraft use the same or similar warning alarms for different alarm conditions?" Tags="&lt;cockpit&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21904" PostTypeId="1" AcceptedAnswerId="21906" CreationDate="2015-10-12T06:21:15.700" Score="16" ViewCount="2440" Body="&lt;p&gt;Do cockpit panels have an indication that oxygen masks in cabin have been deployed for Pilot information?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="3201" LastEditDate="2015-10-12T07:33:16.907" LastActivityDate="2015-10-12T07:55:53.000" Title="Do cockpit panels have an indication that oxygen masks in cabin have been deployed?" Tags="&lt;oxygen-mask&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21905" PostTypeId="2" ParentId="21902" CreationDate="2015-10-12T06:32:57.763" Score="6" Body="&lt;p&gt;I can't find solid references, hopefully someone will come along who can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 30 degree bank, the most you will normally experience, exerts a force of 1.15g, or 0.15 greater than normal acceleration you feel when motionless.  The autopilot is generally designed to begin descents and climbs with no more than 0.25g and are generally calibrated to manoeuvre in 0.25g increments.  A solid rotate or a firm landing might generate a bit more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's reasonable to work on a range of around 0.75 to 1.25gs. Anything more than that would be uncomfortable for many people.  You should only experience g outside that sort of range in heavy or severe turbulence.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-10-12T06:39:53.640" LastActivityDate="2015-10-12T06:39:53.640" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21906" PostTypeId="2" ParentId="21904" CreationDate="2015-10-12T07:34:24.777" Score="13" Body="&lt;p&gt;Yes, there is an indicator for passenger oxygen status.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bgXN0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bgXN0.jpg&quot; alt=&quot;B737 Passenger Oxygen&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.b737.org.uk)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-10-12T07:34:24.777" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21907" PostTypeId="2" ParentId="21904" CreationDate="2015-10-12T07:52:06.307" Score="11" Body="&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/21906/572&quot;&gt;SentryRaven answer&lt;/a&gt;, this is the same for Airbus (A320):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gzFIG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gzFIG.png&quot; alt=&quot;A320 FCOM Panel&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.smartcockpit.com/docs/A320-Oxygen.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FCOM A320&lt;/a&gt; at SmartCockpit.com)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-10-12T07:55:53.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21908" PostTypeId="2" ParentId="21859" CreationDate="2015-10-12T08:12:34.130" Score="2" Body="&lt;p&gt;The same basically applies to Europe. QFE is mostly used by glider pilots, whereas powered aircraft use QNH settings. Most visual approach charts or airport charts have the pattern altitude indicated at the visual representation of the pattern, at airports where no pattern altitude is provided or depicted, you use the rule of thumb to add 1000ft to the airport elevation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below image shows the pattern altitude at Cottbus-Drewitz, where the airport elevation is 274ft but the pattern altitude is 1100ft MSL and the other image the pattern at Lauenbrück, where the airport elevation is 76ft, but no pattern altitude is given. The calculated pattern altitude would be 1100ft (76ft rounded to 100ft + 1000ft).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/735em.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/735em.jpg&quot; alt=&quot;Flugplatz Drewitz Pattern&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://fotos.verwaltungsportal.de/seitengenerator/gross/k800_cottbus-drewitz_edcd_1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.flugplatz-drewitz.de&lt;/a&gt; - Pattern with Altitude in MSL)&lt;/sup&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8Pu76.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Pu76.jpg&quot; alt=&quot;Flugplatz EDHU Pattern&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.edhu.de/images/AIPVFR_EDHU.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.edhu.de&lt;/a&gt; - Pattern without Altitude - Airport ELEV 98ft)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-10-12T08:12:34.130" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21909" PostTypeId="1" AcceptedAnswerId="21910" CreationDate="2015-10-12T08:41:43.123" Score="8" ViewCount="629" Body="&lt;p&gt;GA aircraft use a squat switch to prevent accidental retraction on the ground. Do airliners use a similar system? I've heard some reference to a manual pin, I'd appreciate clarification on that.&lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2019-02-27T17:45:14.017" Title="How do airliners prevent raising the gear on the ground?" Tags="&lt;landing-gear&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21910" PostTypeId="2" ParentId="21909" CreationDate="2015-10-12T08:54:41.210" Score="11" Body="&lt;p&gt;Most airliners have a protection system for this which is based on Weight-on-Wheels (WoW): sensors which detect load on the wheels (which implies that the aircraft is in contact with ground). For safety reasons this can be bypassed and there's usually a small lever in connection to the gear lever to do this. This image illustrates the 737 gear lever where you can clearly see a &quot;lock override&quot; which fills this functionality (red part) &lt;a href=&quot;https://i.stack.imgur.com/2iMuZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2iMuZ.jpg&quot; alt=&quot;lock override&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1344" LastEditorUserId="1344" LastEditDate="2015-10-12T11:34:13.900" LastActivityDate="2015-10-12T11:34:13.900" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21911" PostTypeId="2" ParentId="21903" CreationDate="2015-10-12T09:02:16.760" Score="1" Body="&lt;p&gt;&lt;em&gt;Has boeing changed their alarm systems post that incident?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The story of &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;nofollow&quot;&gt;Helios Airways flight 522&lt;/a&gt; is complicated. It is not clear that a misidentified alarm was the cause of the crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Update:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are talking about the cabin altitude warning horn, that was allegedly misidentified as a take-off configuration, then nothing has been changed, at least up to May 2015 (see: &lt;a href=&quot;https://books.google.ca/books?id=J6wnCQAAQBAJ&amp;amp;pg=PA50&amp;amp;lpg=PA50&amp;amp;dq=cabin+altitude+warning+horn+sound&amp;amp;source=bl&amp;amp;ots=wuFW0U3eSW&amp;amp;sig=xMsIlDX_nU-tA_a_5Zvhtqtfvfw&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0CDwQ6AEwBWoVChMI1ODDkdK8yAIVQqA-Ch2WTQJb#v=onepage&amp;amp;q=cabin%20altitude%20warning%20horn%20sound&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;The Boeing 737 Technical Guide, Version 70, May 2015&lt;/a&gt;, bottom of the page 50).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;&lt;em&gt;As the aircraft climbed, the pressure inside the cabin gradually decreased. As it passed through an altitude of 12,040 feet (3,670 m), &lt;strong&gt;the cabin altitude warning horn sounded&lt;/strong&gt;. The warning should have prompted the crew to stop climbing, but it was misidentified by the crew as a take-off configuration warning, which signals that the aircraft is not ready for take-off, and can only sound on the ground.&#xA;  In the next few minutes, several warning lights on the overhead panel in the cockpit illuminated. One or both of the equipment cooling warning lights came on to indicate low airflow through the cooling fans (a result of the decreased air density), accompanied by the master caution light. The passenger oxygen light illuminated when, at an altitude of approximately 18,000 feet (5,500 m), the oxygen masks in the passenger cabin automatically deployed.&lt;/em&gt;&quot;m, Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;nofollow&quot;&gt;Helios Airways Flight 522&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-12T10:04:56.140" LastActivityDate="2015-10-12T10:04:56.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21912" PostTypeId="2" ParentId="21870" CreationDate="2015-10-12T09:02:24.207" Score="2" Body="&lt;p&gt;I recently saw something like this in a document about a supersonic concept plane (by boeing or airbus, I don't remember)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main part here was that it isn't really the airplane that is &quot;boomless&quot; but rather that it is capable of flying a &quot;boomless&quot; (note the quotes i'll come back to it) flight profile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;boomless&quot; profile they described incuded transitioning to supersonic in near vertical flight (under the power of rockets/ramjets), spreading the shockwave in the horizontal plane, giving it time enough to dissipate energy before it comes near the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cruise altitude of this plane was of sufficient hight to prevent boom issues on the ground (enough hight so that the shock wave would be dissipated by the time it reaches the ground)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically it comes down to a near vertical climb and high altitude flight.&lt;/p&gt;&#xA;" OwnerUserId="11722" LastActivityDate="2015-10-12T09:02:24.207" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21914" PostTypeId="2" ParentId="16449" CreationDate="2015-10-12T10:54:52.073" Score="5" Body="&lt;p&gt;For me, it was a question of how close you were to your 6 monthly Sim check. The closer you were the more handling practice you gave yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, on a normal line flight, I agree, around 400 feet on acceleration and as the BAe 146 had no Autothrust I generally hand flew most of the approach from decelerating, taking flap 18 and putting the gear down. It was my feeling that a human pilot coped better with configuration changes than the autopilot and with no autothrust I wanted to be completely in the loop and therefore, completely flying the aircraft rather than having the autopilot take care of 3 axes and juggling the thrust manually.&lt;/p&gt;&#xA;" OwnerUserId="11724" LastActivityDate="2015-10-12T10:54:52.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21916" PostTypeId="1" AcceptedAnswerId="21923" CreationDate="2015-10-12T12:46:42.057" Score="1" ViewCount="45504" Body="&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/17365/should-landing-light-be-off-during-line-up-and-wait-position#comment40874_17367&quot;&gt;comment&lt;/a&gt; on this website along with an &lt;a href=&quot;https://aviation.stackexchange.com/a/17369/3394&quot;&gt;answer&lt;/a&gt; for the same question added confusion to my mind. Before reading this, I thought taxi lights and landing lights were the same, which seems to be true is some cases. I thought those lights were used for approach, taxiing, and take off and were strong lights designed to light the floor in front of the aircraft in the darkest night. Moreover, the answer linked above speaks of exterior lighting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I got a serie of questions to clarify the role of those &quot;exterior lighting&quot;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are the difference between them (landing lights, taxi lights, other exterior lights I never heard of)? &lt;/li&gt;&#xA;&lt;li&gt;What purpose do they serve and when are they used? (Perhaps it is the same question)&lt;/li&gt;&#xA;&lt;li&gt;Are all aircrafts equipped with?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2019-04-06T11:55:16.187" LastActivityDate="2019-04-06T11:55:16.187" Title="What is the diffference between landing lights, taxi lights and external lights?" Tags="&lt;aircraft-external-lights&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ClosedDate="2015-10-12T15:20:03.023" ContentLicense="CC BY-SA 3.0" />
  <row Id="21917" PostTypeId="1" CreationDate="2015-10-12T13:07:27.730" Score="5" ViewCount="1128" Body="&lt;p&gt;The Wright brothers and the 1 pound crow that flies at 37 km/h expending just 7.68 W &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an 1905 letter to Octave Chanute, Wilbur Wright evaluated the power, used by a 1 lb bird to fly at 34 ft/s, utilizing a relation that can be rewritten as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;eff x Power = Thrust X Speed = Drag x Speed&lt;/strong&gt;,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where: eff (the efficiency of the crow) = 75%, Drag/Lift = Drag/(mg) = 1/8 and mg = 1 lbf.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In consequence, Power = (1 lbf x (1/8) x 34 ft/s ) / 75% = 7.68 W.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The power consumed by any bird or flying machine may be figured from the formula wv/ac, in which w = weight, v = velocity, 1/a = ratio of drift to lift, and 1/c = efficiency of the screws or wings as propellers. In the case of the crow flying at 34 ft. per second, or 2,100 ft. per minute, I would fix the value of l/a at 1/8, and 1/c at 1/.75; when we have (1 x 2100)/(8 x .75) = 350 ft. lbs. per pound of weight.1 The minimum value of l/a may be rendered independent of velocity by regulating the size of the wings. The value of 1/c is about the practical limit of the efficiency of screws under usual conditions, and I see no reason for believing that wings are more efficient than screws, as propellers. It is quite incredible that, when flapping, the wing can be kept at the optimum angle at every point, as in soaring; and there are losses due to the fact that the pressure is not vertical throughout the stroke. Although I think 25 percent a fair estimate of the probable loss from both sources.&#xA;  Birds unquestionably develop power many times greater than is consumed by our Flyer, per pound weight. if you will fix in your mind the distance within which a small bird acquires full speed, say 30 miles an hour, and then figure the power necessary to accelerate its weight to this velocity, I think you will be astonished. I know I was almost dumbfounded, especially in view of the fact that the power available for acceleration is over and above that used in flying. I shall be curious to know what distance you fix upon as that within which a sparrow acquires full speed.&quot;,&lt;br&gt;&#xA;  &lt;a href=&quot;http://invention.psychology.msstate.edu/inventors/i/Wrights/library/Chanute_Wright_correspond/1905/Mar11-1905.html&quot; rel=&quot;nofollow&quot;&gt;Letter of Wilbur Wright to Octave Chanute, Dayton, March 11, 1905&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;7.68 W/lb seems a quite low figure as long as, &lt;em&gt;it's generally accepted that any model plane with less than 50W/lb is going to struggle&lt;/em&gt; (see &lt;a href=&quot;http://www.rc-airplane-world.com/watts-per-pound.html&quot; rel=&quot;nofollow&quot;&gt;The Watts Per Pound rule&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does a crow only expend 7.68 W/lb or at least it is possible to build a model plane able to fly at 37.3 km/h (34 ft/s) developing just 7.68 W/lb shaft power?&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="167" LastEditDate="2015-10-13T00:02:01.693" LastActivityDate="2017-09-12T00:05:02.763" Title="Does a 1lb crow expend only 7.68 Watts to fly at 37 km/h?" Tags="&lt;aerodynamics&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21918" PostTypeId="1" AcceptedAnswerId="21919" CreationDate="2015-10-12T13:15:24.370" Score="2" ViewCount="546" Body="&lt;p&gt;I'm considering the airspeed velocity of an unladen swallow because the swallow may present an opportunity for the observation of nature to lead to better design in aviation. Many technologies built by humans are inspired by designs in nature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one were to set out to determine the airspeed velocity of an unladen swallow, how might they go about this?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-12T13:31:20.947" Title="What is the airspeed velocity of an unladen swallow?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="15" FavoriteCount="2" ClosedDate="2015-10-12T13:41:26.347" ContentLicense="CC BY-SA 3.0" />
  <row Id="21919" PostTypeId="2" ParentId="21918" CreationDate="2015-10-12T13:31:20.947" Score="5" Body="&lt;p&gt;In general, the method of getting the airspeed of any bird is pretty much the same:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Measure the ground speed of the bird.&lt;/li&gt;&#xA;&lt;li&gt;Measure the wind speed in the area.&lt;/li&gt;&#xA;&lt;li&gt;Calculate the airspeed of the bird from these two values.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The following excerpt from &lt;a href=&quot;http://rsif.royalsocietypublishing.org/content/10/86/20130419&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory&lt;/em&gt;&lt;/a&gt; by C. J. Pennycuick et al. published by the Royal Society details one such method:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We measured the bird's air speed, for comparison with the predictions of theory, in two stages. First, we measured the ground speed vector, consisting of the bird's speed relative to the observer's position on the shore and its track direction, i.e. the direction in which the bird was moving over the ground, measured clockwise from true north. We also measured the wind vector consisting of the wind speed and the direction from which the wind was blowing, and then obtained the air speed vector (air speed and heading direction) by vector subtraction of the wind vector from the ground speed vector &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Other researchers have used  Doppler radar for the same purpose and in case of high flying birds, one can simply fly along with the birds at the same speed and measure the airspeed.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-12T13:31:20.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21920" PostTypeId="1" CreationDate="2015-10-12T13:32:35.563" Score="5" ViewCount="2325" Body="&lt;p&gt;At 42.21 minutes of &lt;a href=&quot;https://www.youtube.com/watch?v=tptOpJKFb1w&quot;&gt;this video&lt;/a&gt; about the crash of Helios' Flight 522 (a Boeing 737) caused by cabin depressurization, it was established that a major cause of the crash was a design flaw -- the main wire and the backup of a wire running from the cockpit to the depressurization valve runs through the same channel. So, if one wire burns up and fails, they both do. This is evidently contrary to safe design practices. Also, it seems that the cockpit instruments in the cockpit do not give sufficient indication during the preflight and takeoff checks that this problem exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this video, it appears that this problem has not been addressed by Boeing. Is this still the position on current date?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastActivityDate="2017-08-27T13:53:24.460" Title="Has the design-flaw with the Boeing 737's cabin-pressure switch been fixed yet?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;flight-instruments&gt;&lt;accident-investigation&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21921" PostTypeId="2" ParentId="21916" CreationDate="2015-10-12T13:42:53.110" Score="0" Body="&lt;p&gt;The difference between taxi and landing lights is similar to low and high beam lights in car. Landing lights are much brighter, which is needed to give sufficient visibility during high-speed take-off and landing roll and to make the plane visible from several miles away when in flight, but they would be blinding when used on the apron, so less powerful taxi lights are used when taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultra-light aircraft may not be equipped with any lights at all, so not all aircraft have them, but all aircraft that may be operated at night do. Small aircraft (like Cessna 172) often have the taxi and landing light installed together under one cover, but in most cases there are still two bulbs with different brightness.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-10-12T13:42:53.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21922" PostTypeId="2" ParentId="21916" CreationDate="2015-10-12T13:42:59.517" Score="0" Body="&lt;h2&gt;Landing light&lt;/h2&gt;&#xA;&lt;p&gt;Typically the brightest light on an aircraft. It is like a giant headlight, illuminating the front.&lt;/p&gt;&#xA;&lt;h2&gt;Taxi light&lt;/h2&gt;&#xA;&lt;p&gt;Also a headlight, but not as strong as landing light.&lt;/p&gt;&#xA;&lt;h2&gt;Logo light / Wing light&lt;/h2&gt;&#xA;&lt;p&gt;These lights illuminate the wing or vertical tail surface of an aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DnwUZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DnwUZ.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Landing light is &lt;em&gt;very, very&lt;/em&gt; bright. You turn it on when you want to see what's in front of the aircraft, or you want everybody to notice you. On a clear night you can easily spot an aircraft heading towards you with its landing light some 10 miles away. When you enter a runway, you turn on the landing lights as a way to shout &amp;quot;&lt;em&gt;I'm here. Don't collide on me&lt;/em&gt;&amp;quot; to everybody. If every pilot turns on the landing light at the gate, some ground crews will sure get blinded sooner or later.&lt;/p&gt;&#xA;&lt;p&gt;If you're on a runway, turn on everything.&lt;/p&gt;&#xA;&lt;p&gt;If you're on a taxiway, turn off your landing light but keep your taxi light on. Lights like logo &amp;amp; wing light are optional.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Many aircrafts, especially the smaller ones, do not have wing lights. Some aircraft use the same light as landing &amp;amp; taxi light, in which case you should turn it on during taxi as well unless you want to taxi in the dark.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-12T13:42:59.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21923" PostTypeId="2" ParentId="21916" CreationDate="2015-10-12T14:02:08.687" Score="2" Body="&lt;p&gt;There are basically two types of (exterior) lights in an aircraft- the navigational lights, which are required to be switched on from sunset until sunrise and other forms of exterior lights, which can be switched off at the pilot or operated only at some parts of the aircraft operation, like the landing/taxi lights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A (non-exhaustive) &lt;a href=&quot;http://www.aerospaceweb.org/question/electronics/q0263.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;list of aircraft lights&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Navigation lights&lt;/strong&gt; All aircraft are equipped with a steady light near the leading edge of each wingtip. The starboard light is green while that on the port wing is red. The different colors make it possible for an outside observer, such as the pilot of another aircraft, to determine which direction the plane is flying. These are required to be on during operation (in night).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Navigation or Position lights&lt;/strong&gt; In addition to the red and green lights, most large planes like airliners are also fitted with other steady white navigation lights in various locations like the trailing edges of each wingtip, horizontal tail and top of the vertical tail. The main purpose is to increase the visibility of aircraft from behind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Anti-Collision Beacon lights&lt;/strong&gt; These are are flashing (or strobe) light assemblies installed on the upper and lower fuselage of aircraft,used to improve visibility of the aircraft. These can be switched off at the discretion of the pilot under some conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Strobe lights&lt;/strong&gt; High-intensity strobe lights that flash a white-colored light are located on each wingtip. These flashing lights are very bright and intended to attract attention during flight. They are sometimes also used on the runway and during taxi to make the plane more conspicuous.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Logo lights&lt;/strong&gt; These steady white lights on the surface of or at the tips of the horizontal stabilizer are used to illuminate the company's logo painted on the vertical tail. These are usually switched off in airports to improve the visibility of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7Dnsc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Dnsc.png&quot; alt=&quot;Aircraft Lights&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Navigation lights 2) Aft light 3) Anti-collision strobe lights 4) Logo light&#xA;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Jet-liner%27s_lights_1_N.PNG#/media/File:Jet-liner%27s_lights_1_N.PNG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jet-liner's lights 1 N&lt;/a&gt;&quot; by CC BY 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Wing lights&lt;/strong&gt; Many airliners feature lights along the root of the wing leading edge that can be used to illuminate the wing and engine pylons in flight. These lights may be used to make the plane more visible during takeoff and landing or to inspect the wings for damage in flight. Pilots can also use the wing lights to inspect the wings and slats for any ice accretion that might build up when flying through clouds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Taxi lights&lt;/strong&gt; A bright white lamp is located on the nose landing gear strut of most planes. This light is typically turned on whenever the aircraft is in motion on the ground for greater visibility during taxi, takeoff, and landing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Landing lights&lt;/strong&gt; Typically the brightest light in the aircraft, these are fitted on most planes (and helicopters) for enhanced visibility during the landing approach. These lights can also be used to illuminate the runway at poorly lit airports. They can be located in the wing root, in the outboard wing, or somewhere along the forward fuselage (the usual location incase of helicopters), with some aircraft having them in more than one location.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Hp5Fp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Hp5Fp.jpg&quot; alt=&quot;Boeing 787 lights&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 787 Lights; Source: captalk.net&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Runway Turnoff lights&lt;/strong&gt; Usually located in the leading edge of the wing root, these bright white lamps are intended to provide side and forward lighting during taxi and when turning off the runway. These lights are most useful at poorly lit airports but are usually unnecessary. The lights can also be used in flight if greater visibility is required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Wheel Well lights&lt;/strong&gt; Some planes are equipped with additional lights in the nose and main gear wheel wells. These lights are provided primarily to assist ground personnel in making pre-flight inspections of a plane at night. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The image below shows the lights in a Boeing 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Am1j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Am1j.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from staticflickr.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-12T14:02:08.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21924" PostTypeId="1" AcceptedAnswerId="21926" CreationDate="2015-10-12T15:46:49.290" Score="2" ViewCount="2089" Body="&lt;p&gt;I would like to figure out the service ceiling for Cessna 172N and I couldn't find it anywhere in the POH. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where can I find it? In POH or somewhere else? If in POH, please post a snapshot of it. &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="8000" LastEditDate="2015-10-12T16:00:32.993" LastActivityDate="2015-10-12T16:41:13.187" Title="Where can find Service Ceiling of an aircraft?" Tags="&lt;aircraft-performance&gt;&lt;aircraft-limitations&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21925" PostTypeId="2" ParentId="21924" CreationDate="2015-10-12T15:57:57.210" Score="5" Body="&lt;p&gt;It is in the pilot handbook, &lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;before the title page [PDF]&lt;/a&gt;, under &quot;performance-specifications&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t3Wss.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t3Wss.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2015-10-12T15:57:57.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21926" PostTypeId="2" ParentId="21924" CreationDate="2015-10-12T16:01:10.297" Score="3" Body="&lt;p&gt;It is in the &lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilots Operating Handbook&lt;/a&gt; allright.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PsqQg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PsqQg.png&quot; alt=&quot;Pilots Operating Handbook&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @Dave pointed out, this value can change depending on configuration and other limitation/alterations.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-12T16:41:13.187" LastActivityDate="2015-10-12T16:41:13.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21927" PostTypeId="2" ParentId="21920" CreationDate="2015-10-12T16:19:46.687" Score="11" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot;&gt;Wikipedia article on Helios Airways Flight 522&lt;/a&gt; also mentions this wiring issue, and cites a &lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/5422f090ed915d1374000323/dft_avsafety_pdf_029046.pdf&quot;&gt;separate report regarding a May 2003 incident&lt;/a&gt; in which a 737 had issues with pressurization. During the investigation it was discovered that wiring had shorted and burned in a particular bundle of wires, called a loom, which was important for control of pressurization. The AAIB issued a safety recommendation regarding this issue:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Safety Recommendation 2004-33&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;It is recommended that in order to prevent failure of the cabin pressure control system in the event of damage to wiring loom W298, the Boeing Commercial Airplanes should consider, on the Boeing 737-436 and similarly configured models, separating or protecting the wiring associated with the different modes of operation of this system, which connects the cabin pressure controller to the rear outflow valve, such that any single point failure of the loom would not result in effective failure of the pressurisation control system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In their &lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/548738b8ed915d4c100002b3/Progress_Report_2006.pdf&quot;&gt;2006 progress report&lt;/a&gt;, the AAIB followed up on this recommendation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After a review of the issue and the service history of the pressurization system for the 737-100 thru - 500 model airplane, Boeing felt that modifications of the wiring with the intent of separating the outflow valve functions consistent with the subject safety recommendation &lt;strong&gt;would not significantly contribute towards a reduction in the overall rate of depressurization events.&lt;/strong&gt; Their rationale was based on the basic design philosophy and concept of the original system which includes:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1) A single, mechanical outflow valve which is controlled by a single multi-mode analog pressure controller and driven by independent AC or DC powered electrical motors. Each motor can also be manually commanded open and closed via separate switch on the pressure control panel.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2) In the event of a complete power/control loss (e.g. - electrical interruption or damaged wiring) either motor will remain in last commanded position. The airplane is equipped with an independent aural warning system (cabin above 10,000 feet) and visual cues (cabin above 14,000 feet) should this condition lead to a cabin pressure loss.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;3) The airplane is equipped with both fixed and portable oxygen supply systems for passengers and&#xA;  crew.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;4) If pressure cannot be reliably controlled/restored within a short period of time, the flight crew will utilize procedures (such as rapid reduction in altitude, declaration of emergency and landing at nearest suitable airport) which mitigate the exposure time to low pressure.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Status - Rejected - closed&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the rationale is that if the system fails, the crew is alerted and may take appropriate action. Note &lt;a href=&quot;http://avherald.com/h?article=43778c6b&quot;&gt;the following&lt;/a&gt; regarding an AD published in 2011 with a deadline of March 2014:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA released Airworthiness Directive AD-2011-03-14 requiring all Boeing 737-100, -200, -300, -400 and -500 types to install two additional warning lights, one for takeoff configuration and one for cabin altitude warning, and introduce updated documentation within 36 months following March 14th 2011.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-10-12T16:19:46.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21928" PostTypeId="2" ParentId="21917" CreationDate="2015-10-12T17:04:01.687" Score="6" Body="&lt;p&gt;The number cited by Orville looks quite reasonable. The crow is just cruising along, not banking, accelerating or climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now add a climb speed of just 1 meter (3.3 feet) per second, and the additional power is 5,93 W. Let it circle with 60° bank angle, which would double the required lift, and the power for staying aloft increases to 15.36 W.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next comes the flight speed, which goes up with the root of the wing loading. The &lt;a href=&quot;https://en.wikipedia.org/wiki/American_crow&quot; rel=&quot;noreferrer&quot;&gt;American crow&lt;/a&gt; has a wing chord between 25 and 33 cm and a wing span between 85 and 100 cm. Taking the average puts their wing area at maybe 0.25 m² (it is almost rectangular, after all), and their wing loading at 1.8 kg/m². I would expect that a battery-powered model would have a higher wing loading, maybe 5 kg/m². The required power goes up with the third power of speed, and the speed itself increases with the square root of the wing loading. This makes the model of the crow fly at 62 km/h and consume a power of 35.5 W - just for straight and level flight. Add some margin for acceleration, banking flight and climbing, and the 50W/lb rule looks quite reasonable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-12T19:14:57.407" LastActivityDate="2015-10-12T19:14:57.407" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21929" PostTypeId="2" ParentId="21861" CreationDate="2015-10-12T17:27:06.010" Score="14" Body="&lt;p&gt;It's not &lt;em&gt;technically&lt;/em&gt; an airplane, but I thought I might mention the BV-347, which was an experimental variant of the CH-47 Chinook that Boeing built in the late 60's. Changes included a longer fuselage, retractable wheels, and a pair of rotatable wings. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/rE2RQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rE2RQ.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, one of its weirdest features was a gondola that could be lowered which faced the rear of the helicopter. It had a set of controls and the helicopter could be flown from there. The gondola is the mesh structure below the nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5wtBK.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5wtBK.jpg&quot; alt=&quot;The gondola is the mesh structure below the nose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So not only could the BV-347 be flown from a position that wasn't the nose, it wasn't even facing forward! &lt;/p&gt;&#xA;" OwnerUserId="11727" LastEditorUserId="5517" LastEditDate="2015-10-12T18:37:44.080" LastActivityDate="2015-10-12T18:37:44.080" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="21930" PostTypeId="2" ParentId="1609" CreationDate="2015-10-12T17:45:41.643" Score="1" Body="&lt;p&gt;The engine of an airliner is designed to be as efficient as possible over a journey containing a take-off, a climb, and most of its time at 35000 to 40000 feet where air pressure is about 1/4 to 1/5 of ground level.  The engine has a few extra compression stages to work efficiently at normal cruise at the expense of overheating if flown for long at full power near ground level due to too much compression at the intake.  Look up water injection for an interesting way to get take-off boost in a medium altitude engine in the 707.&lt;/p&gt;&#xA;" OwnerUserId="9889" LastActivityDate="2015-10-12T17:45:41.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21931" PostTypeId="2" ParentId="21903" CreationDate="2015-10-12T17:57:47.860" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If so, what other aircraft have the same sound for different kinds of alarms?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On older LR-JET typed learjets (31, 35, etc) the overspeed and cabin altitude warning sounds are eerily similar.  It hard to tell which one it is without verifying both airspeed indicators.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-12T17:57:47.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21932" PostTypeId="1" CreationDate="2015-10-12T18:29:11.487" Score="8" ViewCount="2647" Body="&lt;p&gt;Assume that an airplane is flying level. If I understood correctly in this situations there are four forces acting on it: weight, thrust, drag and lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift depends on air density, airspeed, wing area and lift coefficient. In the situation described above all of these parameters are constant with the exception of airspeed which can be changed by pilot. So when increasing airspeed lift increases too which makes sense because that seems to be how planes take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However when you watch footage of airplanes accelerating (for instance when a fighter turns the afterburners on) they seem to be able maintain altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this point I see three possibilities:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The airplane doesn't climb or climbs very little because the pilot simultaneously compensates.&lt;/li&gt;&#xA;&lt;li&gt;I have the wrong impression and the airplane does climb.&lt;/li&gt;&#xA;&lt;li&gt;My reasoning above was wrong and there's actually no reason for the airplane to climb further.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So which one is it?&lt;/p&gt;&#xA;" OwnerUserId="11728" LastEditorUserId="4197" LastEditDate="2015-10-13T12:04:06.513" LastActivityDate="2015-10-13T12:04:06.513" Title="Does an accelerating airplane also start climbing?" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21933" PostTypeId="2" ParentId="21932" CreationDate="2015-10-12T18:39:15.023" Score="10" Body="&lt;p&gt;Your (a) assumption is correct -- the aircraft can accelerate without climbing because the pilot compensates.  As the speed increases, an aircraft that was stable &amp;amp; in trim &lt;strong&gt;&lt;em&gt;would&lt;/em&gt;&lt;/strong&gt; naturally tend to climb to maintain airspeed, if the pilot didn't intervene.  To counter this tendency, the pilot applies a slight nose-down input (i.e. elevator down, raises the tail &amp;amp; lowers the nose -- control stick forward).&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-10-12T18:39:15.023" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21935" PostTypeId="2" ParentId="21932" CreationDate="2015-10-12T19:59:08.593" Score="11" Body="&lt;p&gt;You assume that three of the four forces are constant. This is not quite right: Only the mass is given, all the other forces are variable.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thrust $T$: Changes with throttle setting. Also, thrust can vary with flight speed $v$ in a way that can be expressed as $T \propto v^{n_v}$.&lt;/li&gt;&#xA;&lt;li&gt;Lift $L$: Depends on speed and on angle of attack $\alpha$, as in $L \propto v^2 \cdot (\alpha - \alpha_0)$. The accelerating airplane is held level by gradually reducing the angle of attack, such that lift exactly equals weight. The elevator is the instrument for controlling angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;Drag $D$: Like lift, drag depends also on speed and angle of attack: $D \propto v^2\cdot (\alpha - \alpha_0)^2$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Your option a is the correct one: The pilot compensates by adjusting the angle of attack by gradually pushing the stick forward. If he would keep the stick (and consequently the elevator) unchanged, the airplane would climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it might be opportune to introduce the concept of specific excess power ($SEP$). This is the extra power available to the pilot, related to the aircraft weight to make it comparable between airplanes. $$SEP = \frac{P_{eff}-D\cdot v}{m\cdot g}$$&#xA;where $P_{eff}$ is the effective power: $P_{eff} = T\cdot v$. When the pilot commands more thrust than needed for level flight, the excess thrust can be either converted into kinetic energy (speed) or potential energy (altitude). If you look at the units, $SEP$ is a speed. It tuns out that it is the possible climb speed available if flight speed stays constant: $$SEP = v_z$$&#xA;In reality, the practical climb speed is smaller because the airplane needs to speed up when climbing to &lt;a href=&quot;https://aviation.stackexchange.com/questions/420/how-can-i-calculate-maximum-rate-of-climb/12727#12727&quot;&gt;compensate for the decreasing air density&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The possible acceleration is almost as easy to calculate from the specific excess power: $$\ddot x = SEP\cdot\frac{g}{v}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, a mixture of both is also possible, as is trading in one for the other. By adjusting the elevator and with it the flight path, the pilot decides what happens.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-13T06:22:00.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21936" PostTypeId="2" ParentId="21861" CreationDate="2015-10-12T21:00:57.890" Score="9" Body="&lt;p&gt;In a similar vein to the BV-347 example the Erikson Air Crane company operates a Sikorsky S-64 Air Crane with a rear facing cockpit that allows a pilot to fly the aircraft with a less restricted view than they would have from the cockpit - especially helpful when trying to precisely place an item it is carrying/delivering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Black arrows denotes where the cockpit is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hcKdS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hcKdS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="2097" LastEditDate="2015-10-13T20:23:32.143" LastActivityDate="2015-10-13T20:23:32.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21937" PostTypeId="1" CreationDate="2015-10-12T21:12:57.187" Score="4" ViewCount="327" Body="&lt;p&gt;Do airlines trust the common sense of the responsible employee, when it comes down to NOT making certain movies available? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides excluding movies not appropriate for minors, are movies like &lt;a href=&quot;http://www.imdb.com/title/tt0475276&quot; rel=&quot;noreferrer&quot;&gt;United 93&lt;/a&gt;, &lt;a href=&quot;http://www.imdb.com/title/tt0417148&quot; rel=&quot;noreferrer&quot;&gt;Snakes on a plane&lt;/a&gt; or &lt;a href=&quot;http://www.imdb.com/title/tt0106246/&quot; rel=&quot;noreferrer&quot;&gt;Alive&lt;/a&gt; officially a no-no? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Otherwise, without an official directive against these movies, aren't airlines risking a blunder and sparking an Internet storm?&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="595" LastEditDate="2015-10-12T22:31:54.477" LastActivityDate="2015-10-12T23:28:42.273" Title="Do airlines black-list certain movies on their inflight entertainment system?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-10-13T01:51:17.747" ContentLicense="CC BY-SA 3.0" />
  <row Id="21938" PostTypeId="1" CreationDate="2015-10-12T21:17:37.680" Score="1" ViewCount="1543" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow noreferrer&quot;&gt;de Havilland Comet&lt;/a&gt; had pressure leaks inside the square windows which resulted in 3 incidents of the aircraft breaking apart in mid-air. A cockpit window has a similar square window and should be susceptible to pressure leaks.&lt;a href=&quot;https://i.stack.imgur.com/GA1r0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GA1r0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:(prosim-ar.com) Here is a Boeing 737 cockpit outer view. As you can see the windows are square which makes them susceptible to pressure leaks because of their square shape like the de Havilland Comet. So why doesn't the Boeing 737 cockpit windows suffer pressure leaks? And what modern methods do engineers use to reduce pressure leaks and why aren't square windows used on airliners any more?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-10-12T21:27:22.290" LastActivityDate="2015-10-12T22:45:09.743" Title="Why don't cockpit windows suffer pressure leaks?" Tags="&lt;airliner&gt;&lt;cockpit&gt;&lt;windows&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2015-10-13T02:04:56.663" ContentLicense="CC BY-SA 3.0" />
  <row Id="21939" PostTypeId="2" ParentId="21938" CreationDate="2015-10-12T22:28:23.943" Score="14" Body="&lt;p&gt;The Comet did not have pressure leaks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The original structure of the Comet, which had a pressurised cabin (a new technology in airliners at the time), featured rectangular windows with sharp 90-degree corners. This concentrated the stresses in the aircraft skin at these points resulting in accelerated fatigue, cracking and finally catastrophic failure of the fuselage starting at a window corner. This first happened to &lt;a href=&quot;https://en.wikipedia.org/wiki/BOAC_Flight_781&quot; rel=&quot;noreferrer&quot;&gt;BOAC Flight 781&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gF7Pt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gF7Pt.jpg&quot; alt=&quot;The first prototype de Havilland DH106 Comet at Hatfield.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first prototype de Havilland DH106 Comet at Hatfield. Note the square windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(From the Imperial War Museum collection, public domain)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hWfCR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hWfCR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A later Comet 4 which now has rounded windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By Ian Dunster (Own work) [CC BY-SA 2.0 uk (&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/2.0/uk/deed.en)]&quot; rel=&quot;noreferrer&quot;&gt;http://creativecommons.org/licenses/by-sa/2.0/uk/deed.en)]&lt;/a&gt;, via Wikimedia Commons)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The photograph you have posted is not a 737. It's a wooden cockpit mock-up intended for a flight simulator. It will never be pressurised, and the builders are more concerned with the overall shape than detail around the windows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at a &lt;strong&gt;real&lt;/strong&gt; 777 cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zTcTI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zTcTI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Source: Chris Sloan, &lt;a href=&quot;http://airwaysnews.com/blog/2013/04/25/speciaal-delivery-flight-event-american-airlines-boeing-777-300er-part-one-vip-tour-of-737-and-777-factory/&quot; rel=&quot;noreferrer&quot;&gt;AirwaysNews.com&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that the corners at the ends of the widows are rounded, as are all the other corners around the window frame. There is one panel (second from left) that appears not to have this treatment. This panel can be opened (although not when the cabin is pressurised) and is built into its own frame that is fitted into the cockpit window structure. A failure in this frame will not propagate to the rest of the aircraft.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-12T22:45:09.743" LastActivityDate="2015-10-12T22:45:09.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21940" PostTypeId="2" ParentId="21920" CreationDate="2015-10-12T23:17:11.143" Score="7" Body="&lt;p&gt;I would like to add that the linked video deviates in major ways from the truth - or at least from the Greek accident board's assessment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, the &lt;a href=&quot;http://www.aaiasb.gr/imagies/stories/documents/11_2006_EN.pdf&quot; rel=&quot;noreferrer&quot;&gt;final report&lt;/a&gt; of the Air Accident Investigation  &amp;amp; Aviation Safety Board (AAIASB) does not mention the wiring problems at all. Nor does it mention anyone noticing a &quot;burning smell&quot; as is said in the video. If they ever considered it a possibility it had obviously been ruled out before the final report was issued. In fact the report &lt;em&gt;does&lt;/em&gt; reference several prior 737 pressurization incidents, each of which were attributed to failures in the &lt;em&gt;operation of the controls&lt;/em&gt; and not any malfunction. Their recommendations all pertain to changes in the wording of procedures and changes in the cockpit warnings, i.e. a different warning horn and more noticeable indicators on the panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;strong&gt;firm&lt;/strong&gt; conclusion of the investigation was that the pressurization switch had been left in the &lt;em&gt;manual&lt;/em&gt; position and the pilots misinterpreted the warning horn. This was evidenced by &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) the position of the switch as it was found in the wreckage&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The cabin  pressure mode  selector was confirmed  to  be  in  the MAN (manual)  position  by  physical witness marks  on the  mode  selector input  shaft  and by electrical continuity  checks in  the mode select  circuitry. *&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;2) the Non-Volatile Memory (NVM) chip inside the controller &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NVM recording  showed  that on  the  accident flight, the cabin  pressure  control  system was being operated  in  the  manual mode. *&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;3) conversations with ground personnel&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Helios  Dispatcher  reported  that the  Captain  referred  to  the  Takeoff  Configuration horn,  and  then the Equipment  Cooling lights. *&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The video also said that the the F-16 pilots saw two people struggling in the cockpit when they arrived. I have no idea where they got this (made it up maybe?) because the investigation states, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When  the flight HCY522 was intercepted  by the F-16s,  the F-16 lead  pilot reported that there  was no  visible  damage to the Boeing  737 aircraft, that the Captain’s  seat was vacant,  the person  in  the  First  Officer’s seat  was not wearing  an  oxygen mask  and  was  slumped  over  the controls,  and some  seated passengers in the cabin were observed wearing oxygen  masks. *&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It appears to me that the linked video, which is titled &quot;Aircrash Unsolved: The mystery of Helios 522&quot; is taking a lot of liberties with reality to make a dramatic &quot;mystery&quot; where no real mystery exists. The fact that the YouTube account that posted it misrepresents it as an episode of &quot;Air Crash Investigation&quot; is bothersome. The latter show usually does a much better job of being accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;* Taken from the AAIASB final report.&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I realize this is really not an &lt;em&gt;answer&lt;/em&gt; to the actual question. Fooot's answer covers the question very well. This should really be placed as a comment but it is way too long for comments.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-12T23:17:11.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21941" PostTypeId="2" ParentId="21937" CreationDate="2015-10-12T23:28:42.273" Score="3" Body="&lt;p&gt;The specific policies relating to in-flight entertainment are a matter for individual airlines. They will tailor content to the demographic of their typical passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air crashes and similar themes are almost universally avoided, but there are significant regional differences leading to films being more or less heavily censored, or simply not offered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example - airlines based in Muslim countries will censor references to pork and pork products, either by deleting the scenes, or editing the dialog, or both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Europeans are tolerant of some nudity, but dislike excessive violence, while the Middle East will censor all sexual language and bare skin, but permit a much higher level of blood and gore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other, lower-level censorship may also occur. Logos of competing airlines can be pixelated or deleted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is important to airlines. In February 2013 a United Airlines flight was diverted because of a 'passenger incident' originating when parents complained about 'inappropriate content' for their young children (&lt;a href=&quot;http://www.telegraph.co.uk/travel/travelnews/9973766/Sexually-explicit-in-flight-film-causes-plane-diversion.html&quot; rel=&quot;nofollow&quot;&gt;http://www.telegraph.co.uk/travel/travelnews/9973766/Sexually-explicit-in-flight-film-causes-plane-diversion.html&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much of this information was sourced from &lt;a href=&quot;http://edition.cnn.com/2014/08/12/travel/secrets-of-in-flight-movies/&quot; rel=&quot;nofollow&quot;&gt;CNN&lt;/a&gt;. Apply your own judgement when assessing the veracity of such a source.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-12T23:28:42.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21942" PostTypeId="2" ParentId="21902" CreationDate="2015-10-13T01:28:42.877" Score="2" Body="&lt;p&gt;There are two basic classes of G-load; static and dynamic. The difference is time; static loads are those placed on the airframe and its contents during relatively sustained maneuvers like climbing, banked turns, etc. Dynamic loads are transient; turbulence and touchdown are the two big ones. Which one we're talking about is very germane to the question; most maneuvers deal primarily with a static load caused by the change in direction of travel over a sustained turn or pitch-up, however dynamic loads from turbulence while maneuvering must also be accounted for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also very relevant is the weight of the aircraft at the time of a g-loading event; g-forces are always a multiple of this mass relative to the force of gravity on that mass. The weight used for rating purposes is usually the aircraft's max take-off weight, because this is the heaviest that a plane is expected to be while flying (and thus subject to maneuvering loads), and so the most pessimistic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For static G-forces, the 737 class operating G-range is between +2.5g to -1.0g at MTOW in &quot;clean&quot; configuration (reduced to between 2.0-0.0g under full flap). Multiplied by the 737-800's MTOW of 79,000 kg (174,165 lbs), we get a critical number when talking about such things, which is known as the &quot;design load limit&quot;, which for the 738 is 197,500 kg (435,412 lbs). The aircraft's combination of mass and G-loading should not exceed this number. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means the aircraft can, theoretically, withstand much higher g-forces on a ferry flight when there are no passengers or cargo; at the 738's operating empty weight of 41,145 kg (90,710 lbs), the DLL represents a maneuvering of 4.8g. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are unlikely ever to get anywhere close on the average passenger flight in a sustained maneuver; such a banked turn would be hard even for the pilots to sustain. A &quot;steep turn&quot;, using wing bank in the 20-40* range, is about the steepest maneuver you're likely to experience on a commercial airliner, when ATC asks for a &quot;nonstandard turn&quot; during approach or departure to fit the plane through a gap in traffic. Even in this maneuver, you're unlikely to feel more than about 1.25g of force pushing you more firmly in your seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft, however, can take even more. The DLL is the &quot;safe working load limit&quot; of the aircraft under normal conditions, which pilots and airlines shouldn't exceed. To prove the airframe can handle that load, every flying airframe is &quot;proofed&quot; to 1.125x the DLL (representing a 2.8g load at MTOW) which it must survive without structural compromise (&quot;bending&quot;). A sacrificial example of the airframe is also failure-tested to the &quot;Design Ultimate Load&quot;, a static load of 1.5 times the DLL (representing a 3.75g load at MTOW); it must withstand at least this load for 3 seconds without structural failure (&quot;breaking&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA regs (Title 14 Part 25) state that any &quot;Transport&quot;-category aircraft (encompassing virtually all commercial airliners) must be demonstrated to withstand a loading of at least 2.5g at MTOW, but do not have to be able to withstand more than 3.8g at MTOW. In addition, there is a general requirement that the aircraft must be able to withstand any vibration, buffeting or turbulent forces that could occur at any speed up to the &quot;design diving speed&quot; V&lt;sub&gt;D&lt;/sub&gt;, and must withstand any additional forces that could be imparted to the aircraft by a failure or malfunction of any part of the flight control system at speeds up to the airframe's &quot;design cruising speed&quot;, V&lt;sub&gt;C&lt;/sub&gt;. So, all airliners from the little Bombardier narrow-bodies up to the A380 have to be able to at least match the 737 in their g-loading capabilities.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-13T17:48:13.377" LastActivityDate="2015-10-13T17:48:13.377" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21943" PostTypeId="2" ParentId="21858" CreationDate="2015-10-13T04:02:22.393" Score="15" Body="&lt;p&gt;Whether you have the ROW or not, it is your responsibility to &quot;see and avoid&quot; even if the other pilot isn't. This is the aviation analog to defensive driving; call it &quot;defensive flying&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no hard-and-fast rules for collision avoidance maneuvers. You basically have six options and their combinations, any of which will put you at a different point than you would be at the expected intercept (collision) point: climb, descend, turn left, turn right, speed up, slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a study conducted by students at the University of Illinois at Urbana-Champaign, results available &lt;a href=&quot;http://www.aviation.illinois.edu/avimain/papers/research/pub_pdfs/techreports/00-01.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, which might be helpful. The primary purpose of the study was to determine the usefulness of a computer traffic display in aiding the pilot to spot and avoid the traffic, but a secondary goal was to determine the most likely (and safest) collision avoidance maneuvers when presented with &quot;intruders&quot; on a collision course in each of 12 basic intercept paths (overtaking, crossing, or approaching, from the left or the right side, and climbing, level or descending). Among the lessons learned were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots (CFIs were used) were most likely to maneuver purely in the vertical to avoid traffic, moving opposite the vertical direction of the plane in sight and preferring to climb if the intruding traffic was holding altitude.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Despite the pilots' preference for the vertical, the maneuvers that cleared the &quot;conflict&quot; in the shortest time were in the horizontal plane, either turning opposite the plane's relative direction of travel to move behind, or slowing to let the traffic pass in front.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots tended to do what was &quot;easiest&quot; at the time the conflict arose, especially if the intruder was sighted late (because the traffic didn't appear on the computer display; another of the variables they tested). Thus, single-axis maneuvers were most common (not counting the use of throttle to adjust power while performing a maneuver, such as cutting power to dive or increasing it to climb or turn).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Taking all this under advisement, the maneuver most likely to avoid a collision with another plane in otherwise clear skies is a level 30-45° turn in the direction of the intruding aircraft's tail, coupled with a reduction in airspeed if the intruder is on a crossing or approaching route (if he's coming up behind you, maintain airspeed). If the other pilot sees you and reacts at the same time, his most likely move will be a climb, which is fine; if he doesn't see you or react at all, you'll pass safely behind him at the same altitude hopefully avoiding his wake (if he's bigger than you).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there's some interesting game theory here. Any maneuver I tell you to make, except one, will keep you on a potential collision course if the other pilot reacts in the same way at the same time. As you supposed in your question, If you both climb, or dive, or speed up, or slow down, or try to turn behind each other, you'll crash (or at least get way too close for comfort). So, anything I tell you to do because it's unlikely the other pilot will do the same will be self-defeating, because eventually other pilots will do the same thing because it works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one move that won't result in a collision if mirrored is a 90° turn in the &lt;em&gt;same&lt;/em&gt; direction as the intruder's movement across your vision. If he's on your left moving right, turn right 90°. If he's on your right, turn left. If the other pilot mirrors your maneuver, worst-case (an aircraft overtaking you directly from behind who turns the same way as you) you'll end up on parallel flight paths at whatever distance you first noticed each other. Best-case, you'll be heading away from each other and after a couple of minutes you can both reverse your turn and continue along your original heading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, this move is the &lt;em&gt;worst&lt;/em&gt; thing you can do in several scenarios if the other plane holds its course. In high-offset crossing routes (close to 90°), turning away from the intruder will keep you out in front of him and probably too close for comfort, especially if he's faster than you (turning the crossing-route collision course into an overtaking collision).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, any formulaic maneuver we dream up in a two-plane scenario is going to break down when you add more planes, or restricted airspace, or weather. The maneuver may work in cross-country flight, but when dealing with merging Victor airways near a population center, there will be too many aircraft for any single avoidance maneuver to guarantee you'll get out of trouble without getting into more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, ultimately, your call.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-13T17:40:17.003" LastActivityDate="2015-10-13T17:40:17.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21944" PostTypeId="1" CreationDate="2015-10-13T06:35:50.907" Score="6" ViewCount="435" Body="&lt;p&gt;I am aware of the advantages that codesharing has on airlines such as &#xA;- allowing airline to expand operations without physically flying to that destination &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;creating perception of large flight network&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;reduced operation costs from seat transfers e.g KLM &amp;amp; Kenya Airways on the NBO-AMS route&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However my concern is ;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;are there any other further benefits ?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;do codeshares reduce competition?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;can codesharing airlines compete ? (e.g Star Alliance members, Lufthansa &amp;amp; Thai Airways)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;do alliances reduce competition ?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;can airlines of the same alliance compete ? (e.g Oneworld members, British Airways &amp;amp; American Airlines)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="11606" LastActivityDate="2015-10-13T07:01:17.523" Title="Do codeshare &amp; alliances conflict with competition?" Tags="&lt;commercial-aviation&gt;&lt;airlines&gt;&lt;codeshare&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21945" PostTypeId="2" ParentId="21897" CreationDate="2015-10-13T06:44:30.200" Score="3" Body="&lt;p&gt;As per the report published in the website:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In response to queries, SIA said the nose gear of the aircraft retracted while the aircraft was at Gate A17 undergoing a landing gear system check at around 8am on Sunday morning. At the time of the incident, there were no passengers or crew on board, but an engineer was on the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aircraft was undergoing on a landing gear system check, so engineer is using the ladder to reach out the complete system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, it is ladder. Also you can see some other picture which shows the door tore apart due to air bridge because of landing gear crashing.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="9966" LastEditDate="2015-10-13T07:40:48.847" LastActivityDate="2015-10-13T07:40:48.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21946" PostTypeId="1" AcceptedAnswerId="21950" CreationDate="2015-10-13T06:57:21.313" Score="5" ViewCount="11309" Body="&lt;p&gt;I've noticed in some videos,that there are two IRS switches on the 737NG. Why is that so and what is the primary purpose of IRS? Also, what is the alignment of the IRS mean? &lt;/p&gt;&#xA;" OwnerUserId="8346" LastActivityDate="2017-07-01T09:01:15.833" Title="Why are there two IRS switches on the 737NG?" Tags="&lt;boeing&gt;&lt;boeing-737&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21947" PostTypeId="2" ParentId="19241" CreationDate="2015-10-13T06:58:34.530" Score="1" Body="&lt;p&gt;When you next snap open a can of fizzy drink watch carefully at what first comes out of the hole.  A tiny cloud of condensation that quickly disperses.  This is your personal adiabatic decompression demonstrator.  It's exactly the same Physics as what's going on in the photos above.&lt;/p&gt;&#xA;" OwnerUserId="11737" LastActivityDate="2015-10-13T06:58:34.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21948" PostTypeId="2" ParentId="21944" CreationDate="2015-10-13T07:01:17.523" Score="9" Body="&lt;p&gt;Alliances are the airline industry's way of corporate mergers. Since national airlines are still regarded as a symbol of national pride and often are part-owned by the respective governments, eradicating the proud name from the industry would be too hard to swallow. Therefore, alliances are formed in which tariffs and schedules are harmonized. The effect for you, the customer, is the effective removal of competition, resulting in monopoly pricing on routes which are served exclusively by carriers of the same alliance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can be compared to the car industry: Chevrolet is not competing with Pontiac or Cadillac, regardless of what the advertisements say. You might think that the wider choice of brands is a benefit, but in the end the benefits are mainly on the side of the industry.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-13T07:01:17.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21950" PostTypeId="2" ParentId="21946" CreationDate="2015-10-13T07:27:06.617" Score="11" Body="&lt;p&gt;&lt;strong&gt;I&lt;/strong&gt;nertial &lt;strong&gt;R&lt;/strong&gt;eference &lt;strong&gt;S&lt;/strong&gt;ystem is a solid state set of &lt;a href=&quot;https://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;nofollow noreferrer&quot;&gt;3 ring gyros&lt;/a&gt; which navigate using &lt;a href=&quot;https://en.wikipedia.org/wiki/Dead_reckoning&quot; rel=&quot;nofollow noreferrer&quot;&gt;dead reckoning&lt;/a&gt;.  The system measures accelerations in  and rotation around each of the 3 axis so can calculate where it is by adding how much it has moved to the initial position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple example:&#xA;The aircraft is stationary pointing North.  Over a 10 minute period, it measures the accelerations in the X and Y axis and calculates that is has moved +100 kms in the X axis (i.e. North) and +100 kms in the Y axis (i.e. West).  By simple trigonometry, we can calculate that the aircraft is approximately 141.4 kms on a bearing of 45 degrees from it's initial position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gyros must be aligned with the aircraft frame of reference when it is stationary.  This is the &quot;alignment&quot; process and generally must be completed before the aircraft moves.  It may also take inputs of the current position from a manual keyboard or from some other system, e.g. GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More modern IRS fits can align when the aircraft is moving, taking an updated position from GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 2 systems on the 737, simply for redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.slideshare.net/theoryce/b737ng-irs&quot; rel=&quot;nofollow noreferrer&quot;&gt;This slide show gives a good overview.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2017-07-01T09:01:15.833" LastActivityDate="2017-07-01T09:01:15.833" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21951" PostTypeId="2" ParentId="21932" CreationDate="2015-10-13T07:28:14.207" Score="1" Body="&lt;p&gt;A basic &lt;a href=&quot;https://en.wikipedia.org/wiki/Longitudinal_static_stability&quot; rel=&quot;nofollow noreferrer&quot;&gt;stability requirement&lt;/a&gt; for (most) a/c requires the plane to pitch down when speed decreases and pitch up when speed increases. It's called positive speed stability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you decelerate the nose of the plane will point down and the plane will pick up some speed as it begins to descend. It will do so until it picks up a little too much speed and the nose now starts to point a little up, in doing so slowing down a little bit and so on. It's called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Phugoid&quot; rel=&quot;nofollow noreferrer&quot;&gt;phugoid&lt;/a&gt; oscillation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The very same thing will happen when you floor the throttles: speed increases, airplane wants to point the nose towards the sky, plane slows down a little bit, that makes the aircraft want to point the nose a bit below. It wobbles a little bit and then it settles in a nice gentle climb at the very same speed you had before you have pushed the throttle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not the increased lift that makes the a/c climb(in fact you will have &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb&quot;&gt;less lift as you are climbing&lt;/a&gt; and a reduced AoA), it is the stability momentum that pitches the nose up and that makes that extra power from the engines point up. That is what makes you climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how do pilots maintain level flight while accelerating? Pushing the control forward will instruct the tailplane to create less downlift, raising the tail, lowering the nose and counterbalancing the nose up intentions of the plane. You are now still flying level, a bit faster, and a bit more &quot;nose down&quot; mind you: because of the extra speed you now have a lower AoA than before, so your nose is a few minute degrees lower than before when you were slower.&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-13T07:28:14.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21952" PostTypeId="2" ParentId="21946" CreationDate="2015-10-13T08:19:59.907" Score="11" Body="&lt;p&gt;&lt;strong&gt;IRS panel&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are 2 selectors, one for each unit. There are 2 units for redundancy and certification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9Qz1E.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Qz1E.jpg&quot; alt=&quot;B737 NG IRS panel&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.b737.org.uk/navigation.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Purpose of the IRS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The IRS (inertial reference system) function is to provide the aircraft location/attitude in flight, computed from the position/attitude sensed during its alignment and rotation/acceleration variations accumulated since the alignment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An IRS provides a reference to the &lt;em&gt;true&lt;/em&gt; north (and often the &lt;em&gt;magnetic&lt;/em&gt; north equivalence by reading in a table).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airliners, inertial references are generally included in a broader computing chain, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_data_inertial_reference_unit&quot; rel=&quot;noreferrer&quot;&gt;ADIRU&lt;/a&gt;, which also provides air references calculated from air probes (a.g. airspeed and angle of attack).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How it works&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An IRS is composed of 3 &lt;a href=&quot;https://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;noreferrer&quot;&gt;gyro-lasers&lt;/a&gt; (while INS are based on &lt;a href=&quot;https://en.wikipedia.org/wiki/Gyroscope&quot; rel=&quot;noreferrer&quot;&gt;mechanical gyroscopes&lt;/a&gt;) to sense rotation movements, and of 3 &lt;a href=&quot;https://en.wikipedia.org/wiki/Accelerometer&quot; rel=&quot;noreferrer&quot;&gt;accelerometers&lt;/a&gt; to detect linear accelerations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TybM7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TybM7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.authorstream.com/Presentation/bryan7337-1347864-adv-chapter-08-ins-irs-new/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Alignment&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of the IRS alignment is to detect the starting latitude and attitude, by sensing the Earth acceleration. It must be done when the a/c is at rest. To minimize the sensor error, the values sensed are integrated over a period of time (10 mn or so).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longitude which cannot be sensed using Earth acceleration is provided through other means (like GPS or last position).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rBX9O.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rBX9O.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.authorstream.com/Presentation/bryan7337-1347864-adv-chapter-08-ins-irs-new/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Attitude only mode&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the IRS is restarted in flight, then only the attitude can be sensed again. The location reference will be lost (this is what means the ATT mode on the selectors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Use of IRS&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IRS are a complement of the GPS, but IRS has the advantage of being independent of any ground or space equipment. This is why there are still found in the avionics of modern aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Accuracy&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sensing and integration errors accumulates with time after the alignment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Precision of IRS compared to other systems:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5w1ni.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5w1ni.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-10-16T06:18:00.763" LastActivityDate="2015-10-16T06:18:00.763" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="21953" PostTypeId="1" AcceptedAnswerId="21955" CreationDate="2015-10-13T08:24:38.803" Score="8" ViewCount="1643" Body="&lt;p&gt;I wanted to know the number of times a pilot has to refer to his/her checklist for the entire flight (before startup to engine shutdown).&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="62" LastEditDate="2015-10-13T18:02:58.120" LastActivityDate="2016-04-07T21:19:57.267" Title="How many checklists are there for a commercial pilot for the entire flight?" Tags="&lt;commercial-aviation&gt;&lt;checklist&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21954" PostTypeId="2" ParentId="21861" CreationDate="2015-10-13T08:24:49.097" Score="9" Body="&lt;p&gt;Since you didn't specify the type of aircraft, here is one type not controlled by nose :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is what we do all weekend (Although that is not me)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dy3cD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dy3cD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image source:  &lt;a href=&quot;https://cdn.gardenidea.us/medium/4/jet%20rc%20airplanes.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://cdn.gardenidea.us/medium/4/jet%20rc%20airplanes.jpg&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="2171" LastEditDate="2015-10-13T12:43:56.213" LastActivityDate="2015-10-13T12:43:56.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21955" PostTypeId="2" ParentId="21953" CreationDate="2015-10-13T10:24:11.690" Score="10" Body="&lt;p&gt;Typically, the checklists in normal operations are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;External walk around and preflight &lt;/li&gt;&#xA;&lt;li&gt;Before start &lt;/li&gt;&#xA;&lt;li&gt;Before taxi &lt;/li&gt;&#xA;&lt;li&gt;Before take-off &lt;/li&gt;&#xA;&lt;li&gt;After take-off &lt;/li&gt;&#xA;&lt;li&gt;Cruise&lt;/li&gt;&#xA;&lt;li&gt;Descent &lt;/li&gt;&#xA;&lt;li&gt;Approach &lt;/li&gt;&#xA;&lt;li&gt;Landing &lt;/li&gt;&#xA;&lt;li&gt;Shutdown  &lt;/li&gt;&#xA;&lt;li&gt;Secure&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This list is pretty much the same for all aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, each checklist is only used once at the appropriate time but a wise pilot would re-run a checklist if interrrupted.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, you are cleared to start and complete the before start checklist but there is then an unexpected delay before you actually start.  You wait for 30 minutes.  No need to redo the before start checklist because you did it earlier?  No, do it again.  Something might have changed.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="3504" LastEditDate="2016-04-07T17:23:21.427" LastActivityDate="2016-04-07T17:23:21.427" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="21956" PostTypeId="1" AcceptedAnswerId="21958" CreationDate="2015-10-13T10:51:36.293" Score="11" ViewCount="3078" Body="&lt;p&gt;To reduce noise in the London urban area, Heathrow airport has announced plans to trial a steeper approach for aircraft landing - changing from 3 to 3.2 degrees. If this is successful, they will further steepen the landing approach to 3.5 degrees. Moreover, London City airport uses a 5.5 degree landing approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the requirements of higher angle landing approaches and how do they affect flight safety?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="572" LastEditDate="2015-10-15T07:14:32.573" LastActivityDate="2020-04-09T16:08:48.120" Title="What is the requirement of a higher glidepath/approach angle and is this a flight safety issue?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;airport&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21957" PostTypeId="2" ParentId="21956" CreationDate="2015-10-13T11:16:46.487" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the requirement of higher angle landing approach?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is basically requiring the aircrafts to stay at higher altitudes for longer and approaching the ground faster. The normally used term is &quot;&lt;a href=&quot;https://aviation.stackexchange.com/search?q=glideslope%20is%3Aquestion&quot;&gt;glideslope&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;how does it affect flight safety?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The airport authorities will have performed a safety assestment and decided that this change would not sensibly affect flight safety. What will change is how the pilots will have to perform the flare manoeuver (a bit more sharply than before) and for unexperienced students might lead to a higher rate of hard landings, but I doubt that there are many student pilots landing with airliners at those airports.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-13T11:16:46.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21958" PostTypeId="2" ParentId="21956" CreationDate="2015-10-13T11:50:47.660" Score="8" Body="&lt;p&gt;The most important sources of noise in an aircraft (especially during landing) are the engines, the slats/flaps and the gear. An aircraft’s angle of descent has an effect on the noise experienced by people below. Steeper the angle, the less time an aircraft spends at low altitudes, which means that fewer people should be affected by higher levels of noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reduction in noise (as &lt;a href=&quot;http://icana.umwelthaus.org/fileadmin/files/Icana/Dokumentation_ICANA_2013_Teil_2.pdf&quot; rel=&quot;noreferrer&quot;&gt;experienced in Frankfurt airport&lt;/a&gt;) due to steeper (3.2$^{\circ}$) landing approaches are due to the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft is higher (compared to the 3$^{\circ}$ landing angle), and as a result, less noise is heard by the people below.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The deployment of flaps before intercept may also be 0.7 nm closer to the airport as the ILS intercept occurs 0.7 nm closer to the airport.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thrust increase for a/c stabilization 0.3 nm closer to the airport; this results in lower noise. The thrust required was also reportedly lower.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landing gear deployment is 0.4 nm closer to the airport (at the same height of 2000 ft)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The differences due to changing the glideslope to 3.2$^{\circ}$from the present 3$^{\circ}$ is shown in the following image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BlvDz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BlvDz.png&quot; alt=&quot;Effect of change in glideslope&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Experience with the steeper approach angle of 3.2 degrees - Presentation by DLR&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for safety, this system is expected to pose no problems as most aircraft and pilots are easily capable of doing this. As an added measure, the trial is only being carried out when visibility is good (Cat I) and the trial is optional (for aircraft using ILS anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports (like London City) have very steep landing approaches for clearing obstructions and may require special certifications and aircraft modifications.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-13T11:50:47.660" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="21959" PostTypeId="1" CreationDate="2015-10-13T12:31:26.840" Score="6" ViewCount="242" Body="&lt;p&gt;I've researched a bit, and found that entire load of meals may be discarded if a flight is delayed. I've also seen some posts that say first/business class meals are stocked at 110% of capacity. Additionally, some posts say that meals are based on the actual passenger count, rather than the seat count. I'm curious as to the actual practice for determining how many meals make it aboard a commercial flight.&lt;/p&gt;&#xA;" OwnerUserId="11741" LastActivityDate="2015-10-13T12:31:26.840" Title="How does the airline decide how many meals to load aboard a flight?" Tags="&lt;passenger&gt;" AnswerCount="0" CommentCount="3" FavoriteCount="1" ClosedDate="2015-10-13T14:44:27.467" ContentLicense="CC BY-SA 3.0" />
  <row Id="21960" PostTypeId="1" CreationDate="2015-10-13T13:35:16.107" Score="7" ViewCount="432" Body="&lt;p&gt;Has a bad financial situation, or simply being greedy, impacted negatively the safety of an airline or even caused lethal accidents?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that this is &lt;strong&gt;not necessarily a question about low-budget airlines&lt;/strong&gt; like  Ryanair and EasyJet, JetBlue, or Spirit. Low ticket price does not imply the company is in a tight financial situation. No frills does not imply cutting costs at the wrong end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although regulations are the same for all, there are certain scenarios where this seems to matter. No airline will be allowed to skimp on safety issues, but wouldn't having less resources imply:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hiring cheaper pilots, which fulfill minimal requirements, and not much else.&lt;/li&gt;&#xA;&lt;li&gt;Flying routes that are open, but less safe, like Ukraine until recently.&lt;/li&gt;&#xA;&lt;li&gt;Putting more pressure on pilots to fly against their judgment.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="914" LastEditorUserId="1696" LastEditDate="2015-10-15T03:35:58.113" LastActivityDate="2015-10-15T08:07:24.927" Title="Has the financial situation of an airline ever negatively impacted safety?" Tags="&lt;safety&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21961" PostTypeId="1" AcceptedAnswerId="49480" CreationDate="2015-10-13T15:47:17.153" Score="10" ViewCount="3824" Body="&lt;p&gt;I have just acquired an aerobatic aircraft fitted with a Lycoming HIO-360 A1A. Reading the specs on the engine I see it has the higher (8.7:1) compression of the 200hp IO-360 engines, which seem mainly to make that power at 2 700 rpm, but this one actually makes the same power (180 hp) of the 8.5:1 carburetter engines, but at higher rpm (2 900) than they turn. This was a helicopter engine originally which I think accounts for the higher rpm rating, but it seems to me wholly counter-intuitive that an engine with the same swept volume, fuel injection for greater efficiency AND more revs would make - relatively - so little power. Can anyone explain this?&lt;/p&gt;&#xA;" OwnerUserId="11743" LastEditorUserId="1696" LastEditDate="2018-04-17T20:46:05.903" LastActivityDate="2018-10-13T15:08:06.933" Title="Why do the Lycoming HIO-360 A1A and IO-360 engines produce different power?" Tags="&lt;piston-engine&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21962" PostTypeId="1" AcceptedAnswerId="21966" CreationDate="2015-10-13T22:43:10.063" Score="0" ViewCount="6390" Body="&lt;p&gt;At angles of attack like this an airliner would stall very easily. The 787 wing would stall at an angle of 30 degrees. The plane would have been flying at speeds of around 200mph(more likely less) at this angle and speed the aircraft would be very susceptible to stalling? How is this even possible to perform this without stalling?&lt;a href=&quot;https://i.stack.imgur.com/qobSB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qobSB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; Source:&lt;a href=&quot;https://www.youtube.com/watch?v=B5_8D8HCnS4&quot; rel=&quot;nofollow noreferrer&quot;&gt;youtube&lt;/a&gt; The a380 also performed this near vertical takeoff.&lt;a href=&quot;https://i.stack.imgur.com/Y2SSZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y2SSZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:&lt;a href=&quot;https://www.youtube.com/watch?v=a2dcbj488iQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Youtube&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-10-13T23:25:58.803" LastActivityDate="2015-10-13T23:43:01.640" Title="How did this Boeing 787 perform this near vertical takeoff?" Tags="&lt;stall&gt;&lt;angle-of-attack&gt;" AnswerCount="2" CommentCount="8" ClosedDate="2015-10-13T23:33:48.893" ContentLicense="CC BY-SA 3.0" />
  <row Id="21963" PostTypeId="2" ParentId="21962" CreationDate="2015-10-13T22:45:24.333" Score="2" Body="&lt;p&gt;The plane is likely extremely lightly loaded, and it is not flying at 30 degrees AoA. The angle the plane is making with the ground is very high, but the angle it makes with the freestream (i.e. the AoA) is probably still quite small (10-15 degrees at most, I'd expect).&lt;/p&gt;&#xA;" OwnerUserId="11231" LastActivityDate="2015-10-13T22:45:24.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21964" PostTypeId="1" AcceptedAnswerId="21967" CreationDate="2015-10-13T22:49:38.810" Score="12" ViewCount="6696" Body="&lt;p&gt;I've read some documents and articles that reference the FAA's new Airman Certification Standards (ACS) that will soon replace Practical Test Standards (PTS). What is different about ACS and when does it take effect?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="19" LastEditDate="2015-10-14T11:01:59.700" LastActivityDate="2016-04-21T16:03:55.490" Title="How is ACS different from PTS and when does it replace PTS for FAA certification?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21965" PostTypeId="2" ParentId="77" CreationDate="2015-10-13T23:02:48.613" Score="1" Body="&lt;p&gt;Impossible answer...but I'll try.  I owned a 1976 V35B and it cost between 15k-17k per year to own and fly 50-80hrs/yr.  This range included some non-standard repair items and if I REALLY tried I could have been sub-14k but that would have required some serious owner-assisted maintenance that I just didn't have time for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hangar rent can range between 100 and 1000 per month.  Outdoor parking can range from 0 to 200.  It all depends on where you live.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Insurance is the big hurdle for many new pilots.  I'd expect to pay no more than 500-800/yr for a mid range 172 and really good coverage.  The 12k cited in the Mooney example for a new pilot in a medium twin is an extreme example.  You won't see that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 172 should cost no more than 1000 for just the annual inspection. Parts and additional repairs can put you over 1k, but the inspection itself shouldn't be a bear.  Most 172 owners I know escape with sub-1k bills.  Shoot for 55-80/hr for labor.  Now, extra parts and other uncommon (but necessary) maintenance may add to the total cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Budget fuel at 50hrs/yr AS AN ABSOLUTE MINIMUM.  Plan for 75-100hrs/yr if you live in a humid environment (like the gulf coast or mid west).  Consider this a maintenance expense.  You MUST FLY the plane.  Letting it sit sounds cheaper...it's not.  Parts dry out, corrosion sets in, maintenance cost sky rocket.  A flying plane is a happy plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Cessna 172 engine (Continental 300, Lycoming 320/360) will cost a pretty penny to overhaul.  18k cited in the Mooney example is a bargain!  Count on 25k minimum including removal and replacement of the engine.  Spread that cost out over 2000hrs for cost planning.  It's reasonable to expect a well maintained engine to run happily beyond the overhaul recommendation number (called TBO)...which is mostly just a BS number.  Flying beyond TBO is standard practice; I planned to run my IO-520 up to 2500hrs if it let me.  TBO for my engine was 1700hrs.  Every now and then a low time engine goes bad and needs an overhaul.  Ya' pays your money and ya' takes yer chances!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fixed pitch prop is a low-maintenance item.  Maybe plan a few grand for an overhauled prop if yours becomes unservicable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DO NOT fall for the glitzy avionics.  There is nothing wrong with a pair of King or Collins radios and an older GPS unit.  The fancy cockpit panels are nice, but are more for show than function in my opinion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question...I'd budget 12-15k per year to own a decent Cessna 172.  High cost areas (like NYC, San Francisco, Chicago) may see that bleed into the 18k-20k range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My planning:&lt;br&gt;&#xA;-2400 per yr hangar (not covered parking)&lt;br&gt;&#xA;-800 per yr insurance (1m smooth)&lt;br&gt;&#xA;-1200/annual (plan for minor maint issues)&lt;br&gt;&#xA;-2000 per yr fuel - 5 dollars/gal at 8gph&lt;br&gt;&#xA;-800 per yr engine &amp;amp; prop (added some padding)&lt;br&gt;&#xA;-1000 per yr for misc work&lt;br&gt;&#xA;-2400 per yr (assuming a 200 per mo payment)&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...and we're about 11,000/yr without breaking a sweat!  Toss in an unplanned maintenance event, like a starter or battery or alternator or magneto or cylinder or (insert component) and you're crossing 13k real quick.  Now, that does include 50hrs of flying, so you got that going for you...which is nice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please note I only pay 200/mo for a hangar (large city of about 1m people).  I'm absurdly fortunate.  The same hangar at a nearby airport is 450.  Might be over 700 in the bay area.  Needless to say, plan the budget with real numbers from shops, fuel providers, and hangar providers at the airport you intend to fly from.  Call a few insurance brokers and get real quotes, too.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2015-10-13T23:13:07.733" LastActivityDate="2015-10-13T23:13:07.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21966" PostTypeId="2" ParentId="21962" CreationDate="2015-10-13T23:17:12.907" Score="7" Body="&lt;p&gt;First of all, it was nowhere near vertical. It is basically an optical illusion created by the camera angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, and most importantly, what you are seeing is the &lt;em&gt;pitch angle&lt;/em&gt; and not angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it can be readily seen from the following image, the angle of attack and pitch angle can be significantly different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DzJHQ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DzJHQ.png&quot; alt=&quot;Aircraft attitude&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;What is Angle of Attack?&lt;/em&gt; by Boeing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Angle of attack (AOA) is the angle between the oncoming air or relative wind and a reference line (usually fuselage centerline or longitudinal axis in commercial aircraft) on the airplane or wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitch angle (attitude) is the angle between the longitudinal axis (where the airplane is pointed) and the horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight path angle is the angle between the flight path vector (where the airplane is going) and the local atmosphere. In other words, it is the angle&#xA;between the flight path vector and the horizon, as far as a commercial airliner is concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When referenced to the atmosphere, the angle of attack (AOA) is the difference between pitch angle and flight path angle. Depending on the aircraft atitude, they can be &lt;em&gt;very&lt;/em&gt; different. During climb, usually the pitch is increased at constant angle of attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in a steep descent, an aircraft could reach very high angle of attack if the nose is below horizon. While flying upside down (not something that happens in an airliner, I might add) , both differ by around 180 $^{\circ}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the angle of attack in this takeoff is surely well below the stalling angle of 787.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-13T23:43:01.640" LastActivityDate="2015-10-13T23:43:01.640" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21967" PostTypeId="2" ParentId="21964" CreationDate="2015-10-13T23:42:10.943" Score="8" Body="&lt;p&gt;The Airman Certification Standards (ACS) is basically an 'enhanced' version of the Practical Test Standards (PTS). According to &lt;a href=&quot;https://www.faa.gov/training_testing/testing/media/acs_briefing.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA briefing on ACS&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It (ACS) adds task-specific knowledge and risk management elements to each&#xA;  PTS Area of Operation and Task.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general, while the PTS concentrates on what the applicant must 'do', the ACS specifies what he/she must 'know' and 'consider' (in addition to the 'do' part) to qualify for a given airman certificate or rating. The differences (in draft) are shown in this slide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QyjbD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QyjbD.jpg&quot; alt=&quot;ACS Vs PTS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Update on the ACS&lt;/em&gt; by FAA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the FAA briefing,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;• The “skills” section of the ACS covers the flight proficiency performance&#xA;  metrics in today’s PTS.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• For each PTS Area of Operation/Task, the ACS lists the elements of&#xA;  aeronautical knowledge that support that skill.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• In addition, for each PTS Area of Operation/Task, the ACS lists the risk&#xA;  management elements or behaviors associated with it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The ACS is still under development, but FAA is targeting a June 2016 implementation (for airplane) depending on results of prototype (there is one running at the Embry-Riddle Aeronautical University) and some other factors.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-13T23:50:30.897" LastActivityDate="2015-10-13T23:50:30.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21969" PostTypeId="1" AcceptedAnswerId="21971" CreationDate="2015-10-14T01:04:54.123" Score="-2" ViewCount="3873" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UIjBg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UIjBg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; I can never find information for the length of each of these areas. For the cockpit length is the nose to the bathroom and the back of the airplane is the coffee symbol to the tail of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-10-14T01:39:40.693" Title="How long is this part of the Boeing 737 and cockpit?" Tags="&lt;cockpit&gt;&lt;tail&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="21971" PostTypeId="2" ParentId="21969" CreationDate="2015-10-14T01:35:42.100" Score="3" Body="&lt;p&gt;Working from the scale images in the Boeing &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Characteristics for Airport Planning&lt;/a&gt; document:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the 737 models are covered, but as an example, for a 737-800 we see this drawing giving general dimensions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1YGsL.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1YGsL.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scale is given at the foot of the document: 4m per square.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From your illustration the forward dimension looks to be about the first two squares, i.e. 8m, or 26ft 3in, approximately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly the rear dimension is about 2.5 squares, or 10m (32ft 10in.)&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-14T01:39:40.693" LastActivityDate="2015-10-14T01:39:40.693" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21972" PostTypeId="2" ParentId="15671" CreationDate="2015-10-14T03:39:32.103" Score="0" Body="&lt;p&gt;For commercial flights run by carriers or charter companies, the company makes the checklists. These will be based on the manufacturer-recommended checklists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots working for small companies or flying individually make their own standard operation checklists. Usually when a pilot starts flying a type they will use either a manufacturer checklist or a commercially published checklist. Then, at some point the pilot may make minor changes for various reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For non-normal operations (emergencies), the manufacturer checklists are used verbatim.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-10-14T03:39:32.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21974" PostTypeId="1" AcceptedAnswerId="21976" CreationDate="2015-10-14T05:49:34.517" Score="8" ViewCount="1251" Body="&lt;p&gt;KLM has 3 flights daily from BLQ to AMS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do all of the crews handle the flight plans? Do the make a plan for every flight every day or do they have a database in which preset and stored flight plans are available and are ready to be extracted?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-10-15T02:21:08.510" Title="Are airliner flight plans/routes preset?" Tags="&lt;flight-planning&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21975" PostTypeId="2" ParentId="21974" CreationDate="2015-10-14T05:53:46.127" Score="3" Body="&lt;p&gt;Most airlines will have predefined plans, which can be modified as needed (for example when there are NOTAMs).&lt;br/&gt;&#xA;And newer aircraft may even have a standard list of plans preprogrammed in their FMCs, again modifiable of course.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-10-14T05:53:46.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21976" PostTypeId="2" ParentId="21974" CreationDate="2015-10-14T06:01:59.470" Score="15" Body="&lt;p&gt;Airlines have an own department that is solely responsible for their flights and flight plans: &lt;strong&gt;Dispatch&lt;/strong&gt;. Since single airways can have different availability or just direction for different days or even times of the day, there will be a preset pool of routes for recurring flights, which can then be adapted for anything out of the ordinary, like NOTAMS, weather forecasts, operational requirements like airspace closure, etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight plan is usually submitted by the dispatchers and not the aircrew.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-10-14T06:01:59.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21979" PostTypeId="1" AcceptedAnswerId="21991" CreationDate="2015-10-14T11:27:18.977" Score="9" ViewCount="1357" Body="&lt;p&gt;I have noticed at a local airport the AWOS METAR oftentimes is missing visibility measurements. In talking with other more experienced pilots, they tell me this isn't an isolated thing. They indicated that they read between the lines of the other data on the report (or other reports) to get an idea of what weather to expect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&#xA;KTPF 132055Z AUTO 29004KT SCT080 30/22 A2991 RMK AO2 PWINO&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recording always states &quot;VISIBILITY MISSING&quot; meaning it has a sensor and is just... not working?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is it &lt;em&gt;really&lt;/em&gt; normal to see reports without viz?&lt;/li&gt;&#xA;&lt;li&gt;Why does this happen so often for AWOS when ATIS doesn't have problems with it?&lt;/li&gt;&#xA;&lt;li&gt;Should this be reported to some entity (NOAA/FAA) to get these systems repaired or exchanged?&lt;/li&gt;&#xA;&lt;li&gt;The fact that it is missing visibility information does not mean that visibility is unobstructed, right? I have heard people assume this.&lt;/li&gt;&#xA;&lt;li&gt;If the recording says &quot;VISIBILITY MISSING&quot;, is it indicated in the METAR somewhere?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="1696" LastEditDate="2015-10-15T03:34:55.320" LastActivityDate="2015-10-15T19:01:50.717" Title="Is it normal for visibility to be missing from the METAR?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21981" PostTypeId="1" AcceptedAnswerId="23889" CreationDate="2015-10-14T13:01:21.127" Score="61" ViewCount="29694" Body="&lt;p&gt;Yesterday, my little brother asked me to help him build his new &lt;a href=&quot;http://e.fastcompany.net/multisite_files/fastcompany/imagecache/1280/fc_files/2011/1772209-lego-brand-hijacks-the-space-shuttle-takes-over-the-news-rotator.jpg&quot; rel=&quot;noreferrer&quot;&gt;Space Shuttle Lego set&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kv5IH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kv5IH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we finally finished building it, he started to play with his new toy and asked me to be the &quot;Mission Control&quot;. After some time playing, he told me that he had to re-entry and land, so I gave him &quot;permission to re-entry&quot;. Then he started to play as if he was coming back to Earth and told me that the Space Shuttle was too hot and moving too fast to land. And that got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How does the Space Shuttle reduce speed during the re-entry process? &lt;/li&gt;&#xA;&lt;li&gt;Does the Space Shuttle have flaps, spoilers and reverse thrust capabilities?&lt;/li&gt;&#xA;&lt;li&gt;Can the Space Shuttle make a go-around? &lt;/li&gt;&#xA;&lt;li&gt;Where does it land?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I know that when it is on the ground the Space Shuttle can deploy parachutes to reduce speed.&lt;/p&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="15311" LastEditDate="2017-12-10T15:28:58.523" LastActivityDate="2018-07-30T06:20:24.857" Title="How does the Space Shuttle slow down during re-entry, descent, and landing?" Tags="&lt;aircraft-design&gt;&lt;space-shuttle&gt;" AnswerCount="7" CommentCount="12" FavoriteCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="21982" PostTypeId="2" ParentId="21981" CreationDate="2015-10-14T13:18:41.337" Score="5" Body="&lt;ol&gt;&#xA;&lt;li&gt;The space shuttle slows during re-entry using its underside, flying at a very steep angle of attack.. &lt;a href=&quot;https://www.google.ca/search?hl=en&amp;amp;site=imghp&amp;amp;tbm=isch&amp;amp;source=hp&amp;amp;biw=1600&amp;amp;bih=1115&amp;amp;q=space%20shuttle%20reentry&amp;amp;oq=space%20shuttle%20reentry&amp;amp;gs_l=img.3..0l6j0i30l4.1821.5605.0.5913.21.13.0.8.8.0.89.835.12.12.0....0...1ac.1.64.img..1.20.853.SW2owQDp3FQ#imgrc=-YCrOEShLCY7PM%3A&quot; rel=&quot;nofollow&quot;&gt;Here are some images that illustrate what it looks like.&lt;/a&gt;  The re-entry generates a lot of heat and the underside has special heat-resistant tiles to cope with this.&lt;/li&gt;&#xA;&lt;li&gt;During re-entry the shuttle isn't really 'flying' so much using its underside to slow down. At that stage the usual flaps, spoilers and  reverse thrust wouldn't do much. Re-entry refers normally only to the portion where the shuttle is coming into the atmosphere. After a while, when the speed is reduced sufficiently, the shuttle starts to fly more like a normal plane, and uses normal controls. That phase isn't normally called re-entry. When it has actually landed it has a parachute that slows it down, as well as normal wheel brakes, that help slow it down. The engines are nor working during landing, so there is no reverse thrust.&lt;/li&gt;&#xA;&lt;li&gt;The shuttle has no way to make a go-around. &lt;/li&gt;&#xA;&lt;li&gt;The shuttle usually lands at Kennedy Space Center, while early missions and some later ones landed at Edwards Air Force base in California. One missions landed at White Sands base in New Mexico. &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_sites&quot; rel=&quot;nofollow&quot;&gt;Wikipedia has more information&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2015-10-15T13:58:03.267" LastActivityDate="2015-10-15T13:58:03.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21983" PostTypeId="2" ParentId="21981" CreationDate="2015-10-14T13:22:46.817" Score="4" Body="&lt;p&gt;A quick glance at the &lt;a href=&quot;https://en.wikipedia.org/wiki/Space_Shuttle&quot; rel=&quot;nofollow&quot;&gt;Space Shuttle's page on Wikipedia&lt;/a&gt; will answer all your questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, Space Shuttle (more specifically, the &lt;strong&gt;orbiter&lt;/strong&gt; was (last flight was in 2011) no different from any other spaceship/capsule/orbital vehicle/etc.: during re-entry, aerodynamic drag was used to slow down the vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Orbiter was a &lt;a href=&quot;https://en.wikipedia.org/wiki/Lifting_body&quot; rel=&quot;nofollow&quot;&gt;lifting body&lt;/a&gt;, with ailerons/elevators and a rudder that also worked as speedbrake.&#xA;The Orbiter was a &quot;glider&quot; during re-entry, with no propulsion, so a Go-Around was out of question.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-10-14T13:22:46.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21984" PostTypeId="2" ParentId="21981" CreationDate="2015-10-14T13:31:00.010" Score="13" Body="&lt;p&gt;To initiate the landing process, the shuttle executes a deorbit burn&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When it is time to return to Earth, the orbiter is rotated tail-first into the direction of travel to prepare for another firing of the orbital maneuvering system engines. This firing is called the deorbit burn. Time of ignition (TIG) is usually about an hour before landing. The burn lasts three to four minutes and slows the shuttle enough to begin its descent.&lt;br&gt;&lt;sub&gt;&lt;sup&gt;All quotes sourced from &lt;a href=&quot;http://www.nasa.gov/mission_pages/shuttle/launch/landing101.html&quot;&gt;NASA&lt;/a&gt;&lt;/sup&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To reduce speed once in the atmosphere&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To use up excess energy, the orbiter performs a series of four steep banks, rolling over as much as 80 degrees to one side or the other, to slow down. The series of banks gives the shuttle's track toward landing an appearance similar to an elongated letter &quot;S.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To control the shuttle within the Earth's atmosphere&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Early in reentry, the orbiter's orientation is controlled by the aft steering jets, part of the reaction control system. But during descent, the vehicle flies less like a spacecraft and more like an aircraft. Its aerosurfaces -- the wing flaps and rudder -- gradually become active as air pressure builds. As those surfaces become usable, the steering jets turn off automatically.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To make a go-around&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During reentry and landing, the orbiter is not powered by engines. Instead, it &lt;strong&gt;flies like a high-tech glider&lt;/strong&gt;, relying first on its steering jets and then its aerosurfaces to control the airflow around it. &lt;sup&gt;Emphasis mine&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;i.e. it's a glider, no go around available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where does it land:  On the ground, of course!&lt;br&gt;More seriously, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The primary landing site for most shuttle missions was the &lt;a href=&quot;https://www.airnav.com/airport/KTTS&quot;&gt;Shuttle Landing Facility&lt;/a&gt; at &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Landing_Facility&quot;&gt;Cape Canaveral&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Edwards_Air_Force_Base&quot;&gt;Edwards Air Force Base&lt;/a&gt; on the &lt;a href=&quot;http://www.airnav.com/airport/kedw&quot;&gt;Rogers Dry Lake Runways&lt;/a&gt; was an alternate. Edwards was also the primary landing site for the first several (10 or more?) shuttle missions. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_sites&quot;&gt;alternate landing sites&lt;/a&gt; included:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_sites#White_Sands&quot;&gt;White Sands Missile Range&lt;/a&gt; (the only other site to be used)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Vandenberg_Air_Force_Base&quot;&gt;Vandenberg Air Force Base&lt;/a&gt; &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lincoln_Airport_(Nebraska)&quot;&gt;Lincoln Airport/Lincoln Air National Guard Base&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;li&gt;Other locations were emergency abort destinations for use before the shuttle left the Earth's atmosphere.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2015-10-14T14:29:26.773" LastActivityDate="2015-10-14T14:29:26.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="21985" PostTypeId="2" ParentId="21981" CreationDate="2015-10-14T13:33:33.057" Score="9" Body="&lt;p&gt;Source: &lt;a href=&quot;http://science.howstuffworks.com/space-shuttle7.htm&quot;&gt;http://science.howstuffworks.com/space-shuttle7.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When a mission is finished and the shuttle is halfway around the world from the landing site (Kennedy Space Center, Edwards Air Force Base), mission control gives the command to come home, which prompts the crew to:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Close the cargo bay doors. In most cases, they have been flying nose-first and upside down, so they then fire the RCS thrusters to turn the orbiter tail first.&lt;/li&gt;&#xA;  &lt;li&gt;Once the orbiter is tail first, the crew &lt;strong&gt;fires the OMS engines to slow the orbiter down&lt;/strong&gt; and fall back to Earth; it will take about 25 minutes before the shuttle reaches the upper atmosphere.&lt;/li&gt;&#xA;  &lt;li&gt;During that time, the crew fires the RCS thrusters to pitch the orbiter over so that the bottom of the orbiter faces the atmosphere (about 40 degrees) and they are moving nose first again.&lt;/li&gt;&#xA;  &lt;li&gt;Finally, they burn leftover fuel from the forward RCS as a safety precaution because this area encounters the highest heat of re-entry.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What's happening here is that the speed with which the Shuttle is flying around the Earth, which is the speed that keeps it in orbit, is reduced by firing rockets in the opposite direction. Once the speed is reduced enough, the Shuttle starts to fall out of orbit and back to the Earth. It has not yet started to encounter a significant amount of atmosphere at step 4. above.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Because it is moving at about 17,000 mph (28,000 km/h), the orbiter &lt;strong&gt;hits air molecules and builds up heat from friction&lt;/strong&gt; [sic] (approximately 3000 degrees F, or 1650 degrees C).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the next phase of &quot;slowing down&quot;. At this point, keeping in mind step 4. above, the Shuttle has no fuel and no way to power itself. It is now a glider falling down from space. As the Shuttle starts to hit air molecules, compression of the air generates heat (moreso than the friction - an error in the quoted passage), which we can view as a transfer of energy from kinetic to thermal. The loss in kinetic energy is a reduction in the speed of the Shuttle, so the Shuttle is now slowing down to atmospheric speeds. It's a bit tricky because the Shuttle needs air to slow it down, but hitting too much air too fast could cause a rapid heat buildup and destroy the Shuttle. The correct angle of incidence with the atmosphere is key to controlling the rate of heating versus slowing. This is how all manned spacecraft have gone from orbital speed to atmospheric speed since the very first manned missions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When re-entry is successful, the orbiter encounters the main air of the atmosphere and is able to fly like an airplane [sic]. The orbiter is designed from a lifting body design with swept back &quot;delta&quot; wings. With this design, the orbiter can generate lift with a small wing area. At this point, flight computers fly the orbiter. &lt;strong&gt;The orbiter makes a series of S-shaped, banking turns to slow its descent speed&lt;/strong&gt; as it begins its final approach to the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The orbiter is really a glider at this point, not an airplane. It does not have control surfaces as sophisticated as many airplanes do, so the S-turns are used to slow it down.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the orbiter is 2,000 ft (610 m) above the ground, &lt;strong&gt;the commander pulls up the nose to slow the rate of descent&lt;/strong&gt;. The pilot deploys the landing gear and the orbiter touches down. &lt;strong&gt;The commander brakes the orbiter and the speed brake on the vertical tail opens up. A parachute is deployed from the back to help stop the orbiter. The parachute and the speed brake on the tail increase the drag on the orbiter.&lt;/strong&gt; The orbiter stops about midway to three-quarters of the way down the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So while the Shuttle has an airbrake system in the tail, it is generally not used until after touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted elsewhere, there is no ability to go-around. Once the de-orbit burn is past a certain point, the re-entry and landing are fully committed. Given that fact, and the fact that the whole speed management process, line up for landing, flare, touchdown, and roll to a stop have to happen correctly the first time with not a very wide margin of error, we can be impressed at how we've never lost a Shuttle in the landing process, and only one Shuttle during re-entry.&lt;/p&gt;&#xA;" OwnerUserId="8848" LastEditorUserId="8848" LastEditDate="2015-10-14T17:26:01.763" LastActivityDate="2015-10-14T17:26:01.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21986" PostTypeId="2" ParentId="21981" CreationDate="2015-10-14T14:20:13.103" Score="50" Body="&lt;p&gt;The procedure for the space shuttle for re-entering the earth's atmosphere is roughly as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The shuttle is usually flying upside- down, with the vertical tail facing the earth and nose in the direction of flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The shuttle first de-orbits by turning 180$^{\circ}$ (in the yaw axis) and firing the thrusters, thus reducing speed, a procedure called retrofiring (or de-orbit burn).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Then, the shuttle 'flips' ~140$^{\circ}$ (in the pitch axis), so that it enters the atmosphere at around 40$^{\circ}$.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At this point, the atmosphere starts to thicken and the bottom of the space shuttle heats up. Due to the very high angle of attack, the shuttle generates a lot of drag, which helps in reducing speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Then, a series of steep 'S' shaped banking turns at up to 70$^{\circ}$ of bank are performed, while still maintaining the 40$^{\circ}$ angle of attack. This is done in order to reduce the speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;After the completion of the final (banking) turn, the shuttle control is taken over by the commander (it is under pilot control till now), who 'flies' the shuttle (at a negative angle of attack before leveling off) and touches down on the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JbUZB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JbUZB.jpg&quot; alt=&quot;Space shuttle re-entry&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: zlutykvet.cz&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight control system of the shuttle consists of the following components:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Maneuvering engines&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Elevons&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Body Flaps&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Split rudder (which acted as a speed brake).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FRuPq.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FRuPq.gif&quot; alt=&quot;Controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: quest.arc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were no reverse thrusters. The shuttle usually landed at the Kennedy Space Center in Florida or its backup landing site at Edwards Air Force Base in California; Re-entry was a one way trip. There was no go-around as the space shuttle was essentially a very high-tech albeit inefficient glider during the reentry and landing sequence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After touchdown, the pilot chute is deployed after a second, which opens the main (drag) chute, which slows the shuttle down. After the shuttle stops, the drag chute is jettisoned. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JofzZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JofzZ.jpg&quot; alt=&quot;After touchdown&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: spaceshuttleguide.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-15T00:05:19.633" LastActivityDate="2015-10-15T00:05:19.633" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="21987" PostTypeId="1" AcceptedAnswerId="21988" CreationDate="2015-10-14T15:07:10.347" Score="110" ViewCount="34257" Body="&lt;p&gt;While reading about the characteristics of the newest fighter aircraft, I observed that their maximum speed is lower than of the aircraft in the same roles half a century ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the iconic F-14 and Mig-25 have a higher maximum speed than their modern equivalents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the Cold War ended, the major air forces are only engaged in ground support and bombing against low-tech opponents who use asymmetrical warfare, and no modern scenario would see the top fighter aircraft directly engaging each other any time soon. However, for any fighter aircraft in the interceptor role, I would expect speed should be an important characteristic. Also, military aircraft are designed and introduced over a long time period, and are expected to be used for many decades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why did maximum speed become less important? Wouldn't it be easier to design even faster fighters now than with the technology available 50 years ago?&lt;/p&gt;&#xA;" OwnerUserId="1307" LastEditorUserId="1467" LastEditDate="2018-01-23T09:18:56.093" LastActivityDate="2018-01-23T09:18:56.093" Title="Why is the maximum speed of current fighter aircraft lower than those from the 1960's and 1970's?" Tags="&lt;military&gt;&lt;fighter&gt;" AnswerCount="4" CommentCount="16" FavoriteCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="21988" PostTypeId="2" ParentId="21987" CreationDate="2015-10-14T15:26:04.487" Score="188" Body="&lt;p&gt;Speed was life in air combat until the jet age. The pilots who became Air Force generals in the Fifties had learned their trade in the Thirties when speed was the most-desired quality in a fighter. Naturally, the ability to be faster than any adversary was very important to them. When the requirements for new fighter aircraft were written in the Fifties, those generals made sure that a higher top speed was part of the specification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When those supersonic-capable aircraft were used in real conflicts, something very surprising and unforeseen happened: They did hardly ever fly supersonic. When the Air Force in the late Sixties accumulated the flight data from several years of Vietnam war air combat, they found that all aircraft had accumulated just minutes at Mach 1.4 and only seconds at Mach 1.6 out of more than 100,000 combat sorties¹. Never was even Mach 1.8 flown in aircraft which had been optimized for Mach 2.4 (F-104, F-105, F-106A, F-4D/E and F-111).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To cite from this study why speed stayed mostly subsonic:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The first of these reasons lies in the shape of the turn rate vs Mach number relationship for an aircraft. […] In combat, each pilot has the tendency to to fly his aircraft so as to maximize his turn rate. He thus gains angular position on the enemy which, in turn, may permit a missile launch or a gun firing. […] It can be seen that the pilot's urge to maximize his turn rate will unfailingly drive his Mach number to about 0.7. Thus, if the pilot is going to join in combat, […] his speed will inevitably drop to subsonic speeds. […]&#xA;  Note also, that even if the turn rate is held constant while increasing the speed, […] the turn radius and load factor increase, bringing with it increasing problems of keeping the enemy in sight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The second reason given in the study is the dramatically smaller &lt;a href=&quot;https://en.wikipedia.org/wiki/Combat_radius&quot; rel=&quot;noreferrer&quot;&gt;combat radius&lt;/a&gt; (the maximum distance the airplane can travel from its base, accomplish an objective and return) once the aircraft starts to fly at supersonic speeds. Even for flying into the combat arena supersonic speed was rarely advantageous. Northrop studied a multitude of intercept cases and found that speeds above Mach 1.1 were almost never helpful because they curtailed the combat radius severely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need to know that the top speed is an important driver in airframe design. Flying at Mach 2+ requires &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=5%7C0.1494#9222&quot;&gt;heavy and complex intakes&lt;/a&gt;, a heat-resistant structure, high wing sweep and &lt;a href=&quot;https://aviation.stackexchange.com/questions/17706/how-does-a-supersonic-jet-engine-differ-from-a-subsonic-jet-engine/18729?s=12%7C0.2316#18729&quot;&gt;heavy, low-bypass engines&lt;/a&gt;. This all degrades the combat qualities at high subsonic speed, which was where those aircraft were used the most. Building into them the capacity for Mach 2+ made them worse for what they were actually used for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the late Sixties on this lesson was incorporated into the newer designs like the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;noreferrer&quot;&gt;F-16&lt;/a&gt;. Stealth again decreased the importance of supersonic capability, and the maximum sustained speed of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;noreferrer&quot;&gt;F-22&lt;/a&gt; was actually reduced from Mach 1.8 to Mach 1.6 to reduce the heat load on the composite wing leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;¹ Source: &lt;a href=&quot;https://books.google.de/books/about/Northrop_F_5_case_study_in_aircraft_desi.html?id=0Z9TAAAAMAAJ&amp;amp;redir_esc=y&quot; rel=&quot;noreferrer&quot;&gt;Northrop F-5 case study in aircraft design&lt;/a&gt;, AIAA Professional Study Series&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-10-15T14:24:58.140" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="21989" PostTypeId="2" ParentId="21861" CreationDate="2015-10-14T16:06:16.673" Score="7" Body="&lt;p&gt;&lt;strong&gt;Neither the &lt;a href=&quot;https://en.wikipedia.org/wiki/Otto_Lilienthal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lilienthal glider&lt;/a&gt; nor the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_Flyer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wright Flyer&lt;/a&gt; were &quot;nose-controlled&quot;.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Depending on how you define &quot;aircraft&quot;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the early days, the weight of the pilot pretty much &lt;em&gt;defined&lt;/em&gt; the center of gravity, which had to be near the center of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y7rZO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y7rZO.jpg&quot; alt=&quot;Lilienthal glider, picture from Wikipedia (Public Domain)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lilienthal glider, picture in the Public Domain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FmJiJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FmJiJ.jpg&quot; alt=&quot;Wright Flyer, picture by D Ramey Logan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wright Flyer picture &lt;a href=&quot;http://creativecommons.org/licenses/by-sa/4.0&quot; rel=&quot;nofollow noreferrer&quot;&gt;CC BY-SA 4.0&lt;/a&gt; by D Ramey Logan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Others have given answers with lots of examples and pictures. I wanted to point out the historic angle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aircraft didn't &lt;em&gt;become&lt;/em&gt; &quot;nose-controlled&quot; until rather recently. In the beginning, the pilot was nearer to the center than the nose.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="2401" LastEditorUserId="2401" LastEditDate="2015-10-16T07:26:40.007" LastActivityDate="2015-10-16T07:26:40.007" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21990" PostTypeId="2" ParentId="21987" CreationDate="2015-10-14T16:30:08.143" Score="50" Body="&lt;p&gt;Because while speed is one of the important characteristics, it is not the only important characteristic (or today, not the most important one) of a combat aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One important thing to note is that the conditions where top speed is reached is pretty restrictive conditions - high altitude, clean configuration, and afterburners - which are rarely if ever available together in combat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The evolution of the speeds of combat aircraft in general and combat aircraft in particular were a direct result of the experiences of various air-forces in combat situations over the years.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The main reason for the stress on speed of combat aircraft (at least in initial cases) was due to the lessons learned in the WWII, where extra speed can make the difference between life and death.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;After the jets went supersonic, the main reason to have high speeds is for the purpose of interception of enemy aircraft. Speed was the most important requirement in case of combat aircraft (interceptors) half a century ago as the interceptor had to bring the intruder under its range (whether guns or guided missiles). However, the (interceptor) aircraft rarely flew supersonic and as the radars and missiles became advanced, the importance of speed diminished.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another important reason was to escape from the missiles, especially the surface to air missiles. The idea was that the aircraft can outrun the missile, at least at an altitude. However this was a lost cause from the beginning as the missiles flew far faster than the aircraft. For example, the S300 missiles have a top speed of &gt; Mach 7, more than 2 times that of the aircraft it was designed to shoot down. While the combat aircraft are required to be in service for decades, the missile systems can be developed and fielded much more quickly, erasing any speed gains made. As a result, most of the aircraft initially configured for high speed-high altitude attacks switched over to low altitude penetration tactics.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the USAF absorbed the lessons learned in the sixties, it became painfully obvious that the combat aircraft were spending less and less time at very high speeds (&gt; Mach 1.5), while most of the combat devolved into close quarter dogfights (in part due to rules of engagement), where maneuverability, rather than speed is more important. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, the experiences of the Vietnam and Yom-Kippur Wars, where the western aircraft went against sophisticated Soviet Air defense systems reinforced the fact that the suppression of enemy air defenses is more important than speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Designing the aircraft for speed adds significant penalties in the aircraft design- the need for complex air intakes (which adds weight), high temperature materials (which increases cost and maintenance requirements), high powered low-bypass engines (which are usually not fuel efficient). This degrades the other performance parameters of the aircraft in low speed (high subsonic) regime, where most of the operations take place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As it became clear that the combat aircraft are not going to defeat an air defense system by virtue of speed (or maneuverability for that matter), the strategy again changed- not getting detected by the system in the first place. This emphasis on stealth further reduced the importance of speed (you can only heat the composite airframe so much and afterburners for speed are like lighting a torch in the dark for IR sensors) and enhanced that of the avionics and sensors. Today, the stress is on finding the enemy before getting detected and firing the first shot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another reason for high speed is that combat aircraft were also used for reconnaissance, where speed is important (again, for escaping from missiles). However, satellites have taken over most of these duties, further reducing the need for speed. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The epitome of fast combat aircraft is the Soviet Mig-25, which could reach speeds in excess of Mach 3. However, this speed came at a cost- the high temperatures experienced (~300°C) meant that steel had to be used for airframe, requiring complex insulation and cooling systems for avionics and the aircraft rarely flew at this speed due to engine overheating and control issues. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The results (of training and simulation) so far seem to indicate that the modern (fifth generation) aircraft (like F-22) perform better than their fourth generation counterparts (like F-15) in most situations, 'shooting' them down before even getting detected.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-10-14T20:57:58.877" LastActivityDate="2015-10-14T20:57:58.877" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="21991" PostTypeId="2" ParentId="21979" CreationDate="2015-10-14T16:33:45.077" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;My questions are:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Is it really normal to see reports without viz?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes!  Well, maybe not &quot;normal&quot;, but it does happen.  Automated weather stations are like another piece of equipment and components fail from time to time, including the components which measure the visibility.  The other components also fail from time to time (I've see ASOS/AWOS reports without temperature, barometric pressure, etc.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why does this happen so often for AWOS when ATIS doesn't have problems&#xA;  with it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You shouldn't see this at all with ATIS, because a human is involved, and if the equipment which measures visibility is inoperative, a trained observer (often the same person that is manually recording the ATIS) can look out the window and record the visibility themselves.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Should this be reported to some entity (NOAA/FAA) to get these systems&#xA;  repaired or exchanged?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would let the airport manager know just in case they weren't aware.  They are responsible for notifying the FAA.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The fact that it is missing visibility information does not mean that&#xA;  visibility is unobstructed, right? I have heard people assume this. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the visibility is missing, it means just that.  It is missing.  It might be 1/4 SM or it might be 20 SM. Some people may make assumptions that if there is no precipitation, that the temperature / dew point spread is high, etc. that the visibility is good, but that is a potentially dangerous assumption because visibility can be influenced by many different things.  There could even be a dust storm coming through when everything else looks good!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the recording says &quot;VISIBILITY MISSING&quot;, is it indicated in the metar&#xA;  somewhere?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sort of.  It's just &quot;missing&quot; (i.e. the entire wind block from the METAR will not be there), so if you don't see it then, well, it's missing. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-10-15T19:01:50.717" LastActivityDate="2015-10-15T19:01:50.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21992" PostTypeId="1" AcceptedAnswerId="22471" CreationDate="2015-10-14T16:39:17.497" Score="1" ViewCount="230" Body="&lt;p&gt;Does anybody know where to find documentation or someone to ask questions about the SAA database provided by the National Flight Data Center? I have some questions about the ambiguity of some of the data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or better yet, is there a better source for the boundaries and meta data for special-use airspace?&lt;/p&gt;&#xA;" OwnerUserId="87" LastActivityDate="2015-10-28T18:35:14.633" Title="Where to get information on FAA AIXM 5.0 versions of Special Activity Airpace (SAA) files?" Tags="&lt;datasets&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21993" PostTypeId="1" AcceptedAnswerId="21995" CreationDate="2015-10-14T18:28:31.830" Score="10" ViewCount="10760" Body="&lt;p&gt;When is a fuel pump needed on GA aircraft? I am a flight simmer and have noticed that you can leave the fuel pump off and start/fly the aircraft. When would you use the fuel pump?&lt;/p&gt;&#xA;" OwnerUserId="11758" LastEditorUserId="572" LastEditDate="2015-10-14T20:37:20.397" LastActivityDate="2018-10-23T20:07:17.287" Title="When is a fuel pump needed on GA aircraft?" Tags="&lt;general-aviation&gt;&lt;fuel&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21994" PostTypeId="2" ParentId="21993" CreationDate="2015-10-14T18:36:52.963" Score="4" Body="&lt;p&gt;Refer to the POH for the aircraft but in the PA-28-161 I fly the electric fuel pump is used on take off, landing, and while practicing maneuvers like steep turns and stalls. Most GA planes are configured with either a gravity feed fuel system (like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;Cessna 172&lt;/a&gt;) or an engine driven fuel pump (&lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow&quot;&gt;Piper Cherokees&lt;/a&gt;) that can be supplemented with an electric fuel pump should it quit or become partially inoperative. The FAA has a nice &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_ch14.pdf&quot; rel=&quot;nofollow&quot;&gt;document on it here&lt;/a&gt; (see &lt;em&gt;pump feed systems&lt;/em&gt;) their opinion is, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The engine-driven fuel pump acts as the primary&#xA;  pump. The electric pump can supply fuel should the other fail.&#xA;  The electric pump also supplies fuel pressure while starting&#xA;  and is used to prevent vapor lock during flight at high altitude. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The switch you see in the cockpit controls the electric pump. As far as I know there is no way to turn off the mechanical pump (not that you would really want to).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general startup procedure for carbureted PA-28's (low wing mono planes (fuel tank below engine)) often involves turning the fuel pump on, checking for fuel pressure, then turning the pump off. This can also help to prime the lines with fuel, if the lines are dry you will need a few extra cranks of the engine to draw fuel in with the mechanical pump which drains battery power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you claim you can fly with out the pump running we can assume it is an engine pump driven plane however smaller turbine planes that still fall under the GA header may require an electric fuel pump to feed the engine. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-14T20:21:03.227" LastActivityDate="2015-10-14T20:21:03.227" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21995" PostTypeId="2" ParentId="21993" CreationDate="2015-10-14T18:39:17.363" Score="7" Body="&lt;p&gt;On a low wing monoplane you'll need a pump all the time. There will be a mechanical pump fitted to the engine for the purpose. On a high-wing monoplane the engine is often gravity feed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, during critical phases of flight (specifically take-off and landing) you wouldn't want to have that fail so a second auxiliary electric pump is fitted that the pilot switches on beforehand and can switch off once that phase is over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Pilot's Operating Manual will give specific recommendations for use on any given type.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-14T18:39:17.363" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="21997" PostTypeId="2" ParentId="21987" CreationDate="2015-10-14T19:47:26.683" Score="25" Body="&lt;p&gt;One important factor is that the threat model changed as ICBM's replaced bombers as the primary delivery mechanism for nuclear weapons over the course of the 1960s. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being a few seconds late in intercepting a bomber carrying several tons of conventional bombs isn't good and could easily result in a few hundred deaths.  There's a huge difference between that and being a few seconds late in stopping a bomber carrying nuclear weapons where a single bomb can kill tens or hundreds of thousands of people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of particular relevance to the your question the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25&quot;&gt;MiG-25&lt;/a&gt;'s mach 3.2 speed was driven by the threat of the mach 3.0 &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot;&gt;B-70&lt;/a&gt; nuclear penetration bomber program. The US cancelled plans to mass produce and deploy B-70 bombers but the Soviets kept the MiG25 alive.  While the MiG25 was first deployed a few years after the XB70 program was cancelled; the USA continued to build two XB-70's and used them for research purposes throughout the 60s.  The threat of a future supersonic bomber based on the research could not be counted out; and an interceptor significantly faster than the Mach 2 &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_B-58_Hustler#Specifications_.28B-58A.29&quot;&gt;B58&lt;/a&gt; would have remained a valuable part of their nuclear  defense plans until the B58 was retired in 1970.&lt;/p&gt;&#xA;" OwnerUserId="1396" LastActivityDate="2015-10-14T19:47:26.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="21998" PostTypeId="1" CreationDate="2015-10-14T21:03:57.647" Score="2" ViewCount="479" Body="&lt;p&gt;When flying outside the US it is advisable to follow the FAA rules when they are stricter than ICAO, and when it does not violate the local flight governing body's rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you still be fined or get into trouble or does the FAA only have jurisdiction in USA airspace?&lt;/p&gt;&#xA;" OwnerUserId="11761" LastEditorUserId="1696" LastEditDate="2015-10-15T03:31:53.503" LastActivityDate="2015-10-15T03:31:53.503" Title="Is breaking a FAR an issue when flying outside of FAA jurisdiction?" Tags="&lt;faa-regulations&gt;&lt;regulations&gt;&lt;icao&gt;&lt;far-61&gt;&lt;icao-sarps&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="21999" PostTypeId="2" ParentId="21998" CreationDate="2015-10-14T21:44:15.960" Score="2" Body="&lt;p&gt;The FAA only has Jurisdiction over US airspace and you must follow the rules of the airspace you are flying in/through. If you are talking about N registered airplanes they must follow FAA rules for airworthiness etc. even if they are kept outside the country.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is in interesting question on &lt;a href=&quot;https://aviation.stackexchange.com/questions/2358/which-country-is-responsible-for-prosecution-if-a-crime-is-committed-over-intern&quot;&gt;breaking laws on a plane in general&lt;/a&gt; (sort of applicable here)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side Note: Although the FAA does not have jurisdiction outside US airspace if there is an accident involving a US built aircraft (mainly Boeings at this point) the NTSB will send a representative to compile their own report (and aid in the investigation). I know this happens for commercial accidents I am unaware if they send representatives for US build GA plane accidents outside the country. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side Note 2: US pilots licenses are valid elsewhere in the world and allow you to fly elsewhere in the world certain actions elsewhere in the world (if caught/reported) may lead to the revocation of your US issued license. There is some info &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Flight-Training-Ratings-and-Proficiency/Foreign-Pilot-Certification&quot; rel=&quot;nofollow noreferrer&quot;&gt;on that here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-14T21:51:51.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22000" PostTypeId="2" ParentId="21998" CreationDate="2015-10-14T21:58:41.730" Score="2" Body="&lt;p&gt;In international flying you are the servant of many masters.&lt;br&gt;&#xA;Off the top of my head you would be answerable to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The country in whose airspace you are flying.&lt;/strong&gt;&lt;br&gt;&#xA;If the country you're flying in requires you to walk backwards around the aircraft three times while singing &lt;em&gt;Hakuna Matata&lt;/em&gt; prior to takeoff you best start warming up your singing voice.&lt;br&gt;&#xA;In a more practical example some countries &lt;em&gt;require&lt;/em&gt; flight plans for all flights (including VFR flights) - if you're a US pilot flying a US-registered aircraft under visual flight rules in one of those countries you would still need to file a flight plan with the appropriate authorities, even though that's not required under US regulations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The country in which your aircraft is registered.&lt;/strong&gt;&lt;br&gt;&#xA;A US-registered aircraft is subject to US airworthiness requirements, regardless of where it is being operated. If you ignore an airworthiness directive your airworthiness certificate is invalid (and thus you likely can't operate that aircraft anywhere, as the various reciprocal agreements and treaties which would let you operate that aircraft in other countries are contingent upon the airworthiness certificate being &quot;valid&quot;).&lt;br&gt;&#xA;In addition to airworthiness requirements there may be other requirements or restrictions imposed on your aircraft by its nation or registry.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The country which issued your pilot's certificate / air carrier certificate.&lt;/strong&gt;&lt;br&gt;&#xA;A certificated entity is obligated to comply with the regulations of the agency/country issuing that certificate. So a US scheduled airline is still obligated to comply with Part 121 of the FARs, and US pilots are obligated to comply with relevant sections of Part 61 and Part 91.&lt;br&gt;&#xA;For example, if you somehow find a country with no restriction on alcohol use and flying you're still bound by the 8-hour rule in 91.17 - your US (US-issued) pilot certificate could be suspended or revoked for violating that restriction, even if the country you're in doesn't care.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So in order for you flight to be legal you would need to comply with the most restrictive set of applicable laws, regulations, and guidelines.&lt;br&gt;&#xA;Most aviation regulations are broadly similar (thanks to ICAO), so this is not usually a problem, but it's something you would need to be aware of prior to any flight in another country's airspace.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-14T21:58:41.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22003" PostTypeId="1" AcceptedAnswerId="22007" CreationDate="2015-10-14T22:41:12.307" Score="5" ViewCount="401" Body="&lt;p&gt;Reading &lt;a href=&quot;http://www.airlinereporter.com/2015/10/handling-smoke-aircraft/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; regarding an Alaska Airlines 737 Flight that had to turn around back to the gate. There was a following statement:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At the gate, passengers were unloaded five rows at a time, to minimize the risk that the plane would tip under extra weight of fuel. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My general understanding is that the fuel tanks are usually placed near the COG (wings, cargo tanks). Assuming the tanks are still full, why would unloading of passengers all at one time possibly cause the plane to tip? Or is this bad reporting?&lt;/p&gt;&#xA;" OwnerUserId="9567" LastEditorUserId="167" LastEditDate="2015-10-14T23:55:09.570" LastActivityDate="2020-04-01T19:54:57.760" Title="Could improper deplaning of a flight with full fuel tanks cause the plane to tip?" Tags="&lt;airline-operations&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22004" PostTypeId="2" ParentId="22003" CreationDate="2015-10-14T23:02:16.197" Score="5" Body="&lt;p&gt;The 737 had a tendency to tail tip as can be &lt;a href=&quot;https://www.youtube.com/watch?v=JLWxD0gY__A&quot; rel=&quot;noreferrer&quot;&gt;seen here&lt;/a&gt; and &lt;a href=&quot;https://www.youtube.com/watch?v=x0T6jwllAsM&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. They were just being diligent and of loading people in a timely and organized manner to avoid that. You can &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/312494&quot; rel=&quot;noreferrer&quot;&gt;read up on it here&lt;/a&gt; as well. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-14T23:07:28.127" LastActivityDate="2015-10-14T23:07:28.127" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22007" PostTypeId="2" ParentId="22003" CreationDate="2015-10-14T23:09:03.493" Score="6" Body="&lt;p&gt;The 737-900ER has (two) auxiliary fuel tanks in the aft cargo compartment, behind the wing (and center of gravity) with ~3400l capacity for increasing range (from 2800nm to 3,200nm). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In usual conditions, unloading of passengers wouldn't be a problem as the fuel would've been used up; However, as this was an overweight landing with full fuel tanks (the auxiliary fuel tanks weigh ~ 3t), the crew are just being cautious to prevent any incidents.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2020-04-01T19:54:57.760" LastActivityDate="2020-04-01T19:54:57.760" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="22008" PostTypeId="2" ParentId="21960" CreationDate="2015-10-14T23:52:06.580" Score="1" Body="&lt;p&gt;To discuss some of your points directly,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;hiring cheaper pilots, which fulfill minimal requirements, and not&#xA;  much else&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Patrick Smith touches on this in his book &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/1402280912&quot; rel=&quot;nofollow&quot;&gt;Cockpit Confidential&lt;/a&gt; (in regards to cheaper airlines but the same idea applies) and basically comes to the conclusion that PIC time has little to do with anything and the statistical differences are small. He mainly points to the fact that the deadliest accident in aviation the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow&quot;&gt;Tenerife Airport Disaster&lt;/a&gt; occurred not only on the ground but the pilot at the controls was the airlines chief 747 type instructor &lt;a href=&quot;https://en.wikipedia.org/wiki/Jacob_Veldhuyzen_van_Zanten&quot; rel=&quot;nofollow&quot;&gt;Jacob Veldhuyzen van Zanten&lt;/a&gt; and extremely experienced both in type and as a pilot overall.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;flying routes that are open, but less safe, like Ukrania until&#xA;  recently&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The most unsafe thing in this case seems to be commercial planes either intentionally or accidentally being shot down, &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airliner_shootdown_incidents&quot; rel=&quot;nofollow&quot;&gt;you can find a list here&lt;/a&gt;.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;putting more pressure on pilots to fly anyway&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA regulates the hours a pilot must rest for (and an airline cant short cut this) as for departure or not the end call (as far as I know) lies with the pilot. Your takeaway point here is mainly about management putting pressure on employees to do things that may not be safe or may be out of the machines capability. This is not all that dissimilar what some say the cause of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Space_Shuttle_Challenger_disaster&quot; rel=&quot;nofollow&quot;&gt;Challenger disaster&lt;/a&gt; were. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may be able to argue that an airline strapped for cash may put their pilots in poorer accommodations which in turn could lead to a lesser nights sleep and degraded performance but I do not know of that causing any accidents. It did take many years for the FAA to change required rest regulations and you can see &lt;a href=&quot;https://www.faa.gov/news/press_releases/news_story.cfm?newsId=13272&quot; rel=&quot;nofollow&quot;&gt;some of them here&lt;/a&gt;, this was considered a big win for pilots.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-14T23:52:06.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22011" PostTypeId="2" ParentId="738" CreationDate="2015-10-15T01:24:23.150" Score="3" Body="&lt;p&gt;I believe so. Although it is not 100% as accurate as a real flight simulator, it does help you understand a basic concepts which can help you get a boost in starting your understanding in an aviation career&lt;/p&gt;&#xA;" OwnerUserId="11772" LastActivityDate="2015-10-15T01:24:23.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22012" PostTypeId="2" ParentId="21987" CreationDate="2015-10-15T02:02:45.017" Score="15" Body="&lt;p&gt;Maximum speed is not the best speed to fight. Two major factors in a fighter must be taken into account:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot;&gt;Wing loading&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust-to-weight_ratio&quot;&gt;Thrust-to-weight ratio&lt;/a&gt; (T/W ratio).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Wing loading is the weight of the airplane distributed across the total area of the wing. This tells the aircraft's ability to turn sustained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The T/W ratio is the amount of thrust developed by the engine divided by the weight of the aircraft, and this will tell the acceleration the aircraft is able to achieve in level flight. When both things are taken into account, you get a second parameter that is the aircraft ability to climb (&lt;a href=&quot;https://en.wikipedia.org/wiki/Rate_of_climb&quot;&gt;climb rate&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When air war developed in the &lt;a href=&quot;https://en.wikipedia.org/wiki/World_War_I&quot;&gt;WW1&lt;/a&gt;/&lt;a href=&quot;https://en.wikipedia.org/wiki/World_War_II&quot;&gt;2&lt;/a&gt;, one rule of thumb for fighter pilots was that speed/altitude was life. If you examine the aircraft as a physical system of energy, you have two kinds of energy at your disposal: Kinetic energy (the actual rate of aircraft movement) and potential energy, the altitude of the aircraft. When you dive, you convert potential energy into kinetic energy. When you climb you turn kinetic energy into potential energy, until the point where your engine is the only thing that is inputting energy into the system (so you reach the stage where instantaneous climb rate ends and you start to see the sustained aircraft climb rate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When your aircraft turns, it will be slowed a little bit, and the increase in induced drag generated by the turn will decrease your speed slowed. In the fighter pilot jargon, you are burning energy. There are two (again) kinds of turn, instantaneous and sustained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fighting styles where divided into two kinds: &lt;em&gt;Turn and Burn&lt;/em&gt; and &lt;em&gt;Boom and Zoom&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turn and burn means that both fighters try to outturn each order in order to get into their six o'clock position in order to fire, it's a horizontal fight in circles. Boom and Zoom is a climb fight where the higher positioned aircraft dives into the other in order to make a pass, fire and then climb again in order to not lose airspeed (and thus energy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quickly the boom and zoom style was adopted. Experienced pilots only entered combat when sure to have higher altitude than their enemies, because altitude was a reservoir of energy to be exploited in combat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A turn and burn styled fighter/pilot would quickly slow down and be unable to either attack or flee from a higher positioned aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far so good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the war, all efforts went on to produce ever faster aircraft and aircraft able to reach high altitudes quickly. This has dual advantage of giving a better high altitude position and allowing such fighters to engage incoming bombers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All changed when better missiles and onboard radars became available. Not that current fighters don't need to be able to dogfight, but because the missile became the major combat element. Two kinds of missiles come to my head at this stage. &lt;a href=&quot;https://en.wikipedia.org/wiki/Air-to-air_missile&quot;&gt;AAMs&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Surface-to-air_missile&quot;&gt;SAMs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The increasingly powerful radars (even onboard) meant that aircraft might very well attack things that are above it, meaning that the boom and zoom tactics might go wrong. Secondly, a radar allows one to see the enemy way before visual contact is made, giving more time to climb to a similar altitude, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying very high, you will be seen on enemy radar far away, and missiles directed by those radars will come from various directions. To enter enemy airspace, you need to stay low, where air resistance is bigger and most aircraft can't reach the stated figures of speed. (See &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark&quot;&gt;F-111&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-24&quot;&gt;Su-24&lt;/a&gt; for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bombers won't be flying at stratospheric levels like &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress&quot;&gt;B-29&lt;/a&gt; anymore, due to the same reasons. They need to enter enemy airspace at low altitude in order to have a chance of surviving. If they use standoff weapons, those will fly low too. So, if you are escorting a bunch of bombers in a mission, or you are trying to intercept those, they will not be very high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a onboard radar tries to lock against a low flying aircraft, there is a problem. Earlier radars where not able to do so at all. More modern versions (called look-down/shot-down) are able to lock a target against terrain, but not with the same performance as when they are looking up. Clutter (false echoes) is removed via software. Infrared detectors work better at high altitude (where air is colder and a hot fighter is more visible), than against the hot ground below, and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, all in all, fighter combat in intensive theaters will be going to be done at middle or low level, where speed is slower due to higher drag. Even then, all fighter aircraft have something called corner velocity, where the aircraft is able to sustain their most tight turns, and those speeds are usually far from being top speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another factor is engine consumption. Only recently did supercruising aircraft came to be operational. Forth-generation aircraft where not able to break the sound barrier without using afterburns, which both increase aircraft detectability (due to increased heat signature) and fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same aircraft that might travel 1000&amp;nbsp;km without using afterburners, might very well be unable to do more than 300&amp;nbsp;km while afterburning all along.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All things taken into account, an aircraft with more missiles, better radar and longer loiter time is preferred above fighters like the British &lt;a href=&quot;https://en.wikipedia.org/wiki/English_Electric_Lightning&quot;&gt;Lightning&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot;&gt;F-104&lt;/a&gt; which had a very high speed and climb rate, but were short-legged and lugged only a pair of missiles.&lt;/p&gt;&#xA;" OwnerUserId="7265" LastEditorUserId="849" LastEditDate="2015-10-17T11:43:49.807" LastActivityDate="2015-10-17T11:43:49.807" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22013" PostTypeId="2" ParentId="21974" CreationDate="2015-10-15T02:21:08.510" Score="3" Body="&lt;p&gt;They are called company routes. They are customised for an airline and added to a section of the monthly Navigation Database the FMS manufacturer sells to each airline. Flight plans can also be uplinked by the airline operation center to the FMS. Both of these the pilot can select into the active/primary flight plan.&lt;/p&gt;&#xA;" OwnerUserId="11773" LastActivityDate="2015-10-15T02:21:08.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22014" PostTypeId="2" ParentId="2023" CreationDate="2015-10-15T05:24:31.100" Score="11" Body="&lt;p&gt;The recommended phraseology depends on the airport. If it's tower controlled then you're encouraged to use ATC's phraseology per &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;JO 7110.65V&lt;/a&gt;&#xA;(3−10−11):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PHRASEOLOGY− LEFT/RIGHT (if required) &lt;strong&gt;CLOSED TRAFFIC&lt;/strong&gt; APPROVED. REPORT&#xA;  (position if required),&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For uncontrolled airports we see this in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; (4-1-5):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Recommended UNICOM phraseologies:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Outbound PHRASEOLOGY− FREDERICK TRAFFIC CESSNA EIGHT ZERO ONE&#xA;  TANGO FOXTROT DEPARTING RUNWAY ONE NINER. “&lt;strong&gt;REMAINING IN THE&#xA;  PATTERN&lt;/strong&gt;” OR “DEPARTING THE PATTERN TO THE (direction) (as&#xA;  appropriate)” FREDERICK.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern are defined in both JO 7110.65V and the AIM as &lt;em&gt;Closed Traffic&lt;/em&gt;. However, the recommended phraseology for UNICOM is to say &quot;remaining in the pattern&quot;, whereas for towered operations ATC will always use &quot;Closed Traffic&quot;. In practice, pilots and ATC will know what you mean either way.&lt;/p&gt;&#xA;" OwnerUserId="9012" LastActivityDate="2015-10-15T05:24:31.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22015" PostTypeId="2" ParentId="21956" CreationDate="2015-10-15T05:32:59.647" Score="4" Body="&lt;p&gt;Since the forward speed is determined by required lift, steeper approach path means higher vertical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering approach speed of 130 knots:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;at 3.0°, which is 5.2% or 1:19.1, the vertical speed is 690 ft/min,&lt;/li&gt;&#xA;&lt;li&gt;at 3.2°, which is 5.6% or 1:17.3, the vertical speed is 736 ft/min,&lt;/li&gt;&#xA;&lt;li&gt;at 3.5°, which is 6.1% or 1:16.3, the vertical speed is 805 ft/min and&lt;/li&gt;&#xA;&lt;li&gt;at 5.5°, which is 9.6% or 1:10.4, the vertical speed is 1268 ft/min.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since normally the criteria for stabilized approach is that vertical speed does not exceed 1000 ft/min, the 5.5° requires different procedure with different criteria.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical speed equals power (&lt;span class=&quot;math-container&quot;&gt;$P = mgv_v$&lt;/span&gt; where &lt;span class=&quot;math-container&quot;&gt;$m$&lt;/span&gt; is mass, &lt;span class=&quot;math-container&quot;&gt;$g$&lt;/span&gt; is gravitational acceleration and &lt;span class=&quot;math-container&quot;&gt;$v_v$&lt;/span&gt; is vertical speed) and to maintain speed, the engines have to develop less power by this amount, or drag has to be increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is usually not a problem for propeller aircraft, especially those with variable pitch propellers (which turboprop requires and larger piston-engined aircraft have as well). With maximum RPM selected the propeller produces quite a lot of drag at idle, but since everything is already spinning fast, adding power has immediate effect if needed to go around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may, however, be problem for jet aircraft. Jet engines need to spool up to increase thrust and from very low power settings that can take several seconds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The normal glide-slope is well below the gliding angle with no power (with flaps and gear), so the engines are still running at considerable power. In the slightly steeper approaches the power is less, but the difference is not as big, so it usually isn't a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the 5.5° steep approach is getting close to the unpowered glide angle even with full flaps and gear and is steeper than unpowered glide angle with lower flaps settings. This means the engines will react more slowly and pilots have to consider it. Also in some aircraft an engine-out approach can't be flown at full flaps, because the remaining engine(s) would not have enough power for go-around at that drag, which means such aircraft can't fly steep approaches with failed engine. And some aircraft may not be permitted to do these steep approaches at all, because even at full flaps the engines would run too slow and take too long to spool up.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2020-04-09T16:08:48.120" LastActivityDate="2020-04-09T16:08:48.120" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="22016" PostTypeId="2" ParentId="21981" CreationDate="2015-10-15T07:44:42.017" Score="5" Body="&lt;p&gt;To give a less scientific version of what was already stated: there is no need to significantly reduce speed before re-entry as the re-entry &lt;strong&gt;is&lt;/strong&gt; the way to reduce speed. And the Shuttle won't be hot before the re-entry, but rather the re-entry heats it up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some more detail: Yes, the Shuttle needs to slow down before landing. But the reason for its high speed is not that its falling down from such a high altitude. Rather, it's really not that high: AFAIK a typical Shuttle orbit is about 150km above ground. If you compare that to the diameter of Earth at more than 13000km, the Shuttle orbit is actually kind of close to the ground. The reason for its high speed (about 5 miles per &lt;strong&gt;second&lt;/strong&gt;) relative to the ground is that it needs that velocity to &lt;strong&gt;stay&lt;/strong&gt; in orbit and not fall down. That's why the Space Shuttle's sits on such a huge rocket on launch: it is necessary not so much to lift the Shuttle high up, but rather to give it that huge speed needed to stay in orbit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But you can't land a Shuttle at that velocity, so the Shuttle needs to slow down before landing. How do you do it? Using another rocket booster would be an idea. But that would mean carrying huge amount of rocket fuel into orbit. And that in turn would require far bigger rockets at launch to lift and speed up the mass added to the Shuttle by those &quot;brake&quot; rockets. Instead, the Shuttle uses another approach: It is  slowed down only slightly (the &quot;de-orbit burn&quot; explained in other good answers) using its thrusters. This way it cannot maintain its orbit and gets closer to Earth and its atmosphere. The de-orbiting burn does not significantly reduce the Shuttle's velocity, but in the atmosphere its velocity causes significant drag. And its that drag on re-entry that at the same time slows down the Shuttle and heats up its hull.&lt;/p&gt;&#xA;" OwnerUserId="4097" LastActivityDate="2015-10-15T07:44:42.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22019" PostTypeId="1" CreationDate="2015-10-15T07:53:11.060" Score="7" ViewCount="1715" Body="&lt;p&gt;What kind of damage does the ejection process do to the inside of a cockpit or to the aircraft in general? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ejection were accidentally triggered on the ground (i.e. the ejection wouldn't be followed by a hull damaging/destroying crash), would the damage be minimal enough that it could be flown again by simply installing a new seat and canopy, or would it have to go through a major inspection to ensure no additional damage was done to instruments, wiring, etc?&lt;/p&gt;&#xA;" OwnerUserId="9338" LastEditorUserId="5517" LastEditDate="2015-10-15T20:47:16.830" LastActivityDate="2015-10-16T12:51:10.163" Title="Can an aircraft be controlled after an ejection?" Tags="&lt;ejection-seat&gt;" AnswerCount="5" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22020" PostTypeId="2" ParentId="21960" CreationDate="2015-10-15T08:07:24.927" Score="11" Body="&lt;p&gt;Pan American World Airways declared bankruptcy in January 1991. In the year previously they were doing everything they could to to avoid that. To help their cash flow, Pan Am sold five of their 747s for cash to Evergreen International Airlines. The deal was that EIA would immediately lease the five back to Pan Am, which they did. Unfortunately, Pan Am soon defaulted on the lease payments and EIA began repossessing the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EIA gave Pan Am fair warning on the repossession of the first aircraft, at which time Pan Am swapped out good components for crap components before surrendering the aircraft. Not to be taken again, when EIA repossessed the second aircraft, they did so without warning at the gate when the aircraft arrived in JFK from Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was the f.o. on the crew that was sent to get the aircraft. We were in the cockpit setting up when one of our maintenance guys came in and said that they had just received orders to boroscope the engines, which they did while we waited in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After an hour or so, one of our JFK managers came into the cockpit and told us that we wouldn't be going anywhere, that the airplane was not flyable as three of the four engines were significantly below required tolerances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if flying a plane load of passengers across the North Atlantic with three out of four engines below required minimum maintenance standards constitutes a negative impact on safety, then, yes, a bad financial situation did indeed, at least once, cause such.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-10-15T08:07:24.927" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22022" PostTypeId="1" AcceptedAnswerId="22038" CreationDate="2015-10-15T08:32:15.280" Score="3" ViewCount="700" Body="&lt;p&gt;During the testing phase as well as during transport of the Space Shuttle on top of a 747, a boat tail was used:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kIuUi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kIuUi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://static4.businessinsider.com/image/4f919ffb69bedd294400000a-400-300/following-retirement-of-the-space-shuttle-program-nasa-905a-has-been-busy-transporting-space-shuttles-to-the-cities-of-their-final-display-sites.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://books.google.nl/books?id=DiiGdVp1eS0C&amp;amp;pg=PA14&amp;amp;lpg=PA14&amp;amp;dq=space%20shuttle%20boat%20tail%20aerodynamic%20turbulence&amp;amp;source=bl&amp;amp;ots=_ZcMVhI4E2&amp;amp;sig=DzPAwLF50NGQ47fk43RNAPCOPgQ&amp;amp;hl=nl&amp;amp;sa=X&amp;amp;ved=0CCAQ6AEwAGoVChMIu5mls4fEyAIVS70UCh3xLAw2#v=onepage&amp;amp;q=space%20shuttle%20boat%20tail%20aerodynamic%20turbulence&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here&lt;/a&gt; I found that this was mainly to reduce the turbulence that would strike the tail of the 747, thus increasing yaw authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I can also imagine that the boat tail would reduce the base drag of the Space Shuttle, thereby reducing the fuel penalty of carrying the Space shuttle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is there any research that shows that the boat tail also reduced the drag, rather than just providing a cleaner flow to the vertical tail?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-10-15T13:27:58.240" Title="Did the Space Shuttle boat tail used in the transport configuration save fuel?" Tags="&lt;space-shuttle&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22023" PostTypeId="1" CreationDate="2015-10-15T08:41:28.603" Score="3" ViewCount="1289" Body="&lt;p&gt;On the electric panel of the Airbus A340 there are three battery buttons (BAT 1, BAT 2 and APU BAT, indicated by (3) and (4) in the diagram) controlling battery charge limiters. When the aircraft is on the ground, below 50kts and batteries are the only power sources (as FCOM states) batteries 1 and 2 should be connected to the DC-Battery bus (DC_BAT_BUS) and the DC-Essential bus (DC_ESS_BUS). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0Yqmm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0Yqmm.png&quot; alt=&quot;A340 overhead electrical panel&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;source: Airbus A340 FCOM 1.24.20 P1 REV08&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should both of battery buttons 1 and 2 be pressed to Auto mode to have these connections? Or it is possible to connect battery 1 separately from 2 to DC_BAT_BUS? Seems that both buttons should be pressed to have such connection to DC_ESS_BUS, but for DC_BAT_BUS it is not so obvious.&lt;/p&gt;&#xA;" OwnerUserId="11783" LastEditorUserId="19" LastEditDate="2015-10-15T09:12:49.833" LastActivityDate="2015-11-14T10:50:28.667" Title="How is the battery power on the Airbus A340's electric system switched?" Tags="&lt;airbus&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22024" PostTypeId="2" ParentId="22019" CreationDate="2015-10-15T09:33:49.700" Score="10" Body="&lt;p&gt;I'm going to interpret safely as meaning successfully. Ejections mean safety has gone out the window - literally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a case in the Vietnam War where a pilot continued to fly his heavily damaged F-4 after his RIO (back seat radar operator) ejected. He managed to keep it together long enough to get back over friendly territory before ejecting himself. Note, this was an interview I saw some years ago, I haven't been able to find a link to post. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case the airplane had been hit badly enough that landing was not going to happen, however if the RIO had ejected accidentally or the airplane less damaged then a safe landing would have been possible. So yes, flying has been done and landing is entirely possible after someone has ejected. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-10-15T09:33:49.700" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22025" PostTypeId="2" ParentId="22019" CreationDate="2015-10-15T09:48:21.447" Score="7" Body="&lt;p&gt;The fighter can remain airworthy (in the technical sense not in the regulatory sense) after ejecting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cornfield_Bomber&quot;&gt;cornfield bomber&lt;/a&gt; made a belly landing onto a field after the pilot ejected.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-10-15T09:48:21.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22026" PostTypeId="2" ParentId="22023" CreationDate="2015-10-15T10:12:58.050" Score="2" Body="&lt;p&gt;From A340 FCOM 1.24.20 P2 (REV 8):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;BAT 1 (2) pb sw&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Controls the operation of the corresponding Battery Charge Limiter&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;AUTO&lt;/em&gt;: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Battery Charge Limiter controls automatically the connection&#xA;  and the disconnection of the corresponding battery tot the DC BAT BUS&#xA;  by closing and opening of the battery line contactor. &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The batteries&#xA;  are connected to the DC BAT BUS in the following cases:&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Battery voltage below 26.5 Volts (battery charge). The charging cycle ends when battery charge current goes below 4 Amperes (for 10 seconds on ground 30 minutes is flight)    &lt;/li&gt;&#xA;  &lt;li&gt;On the&#xA;  ground (with speed below 50 knots) when batteries only are supplying&#xA;  the aircraft. &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My understanding is that for the DC BAT BUS this means when a button is set to &lt;em&gt;AUTO&lt;/em&gt; the corresponding battery is connected when that battery needs to be charged &lt;strong&gt;or&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The aircraft has a speed below 50 knots &lt;strong&gt;AND&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;The only power source is batteries (i.e. no generators, APU or external power supply are connected to the electrical network)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;A note further down mentions that the batteries are disconnected  when the voltage drops below 23 Volts for more than 16 seconds, in order to protect the battery from discharging completely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the DC ESS BUS it states: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The batteries are connected to the DC ESS BUS when batteries only are&#xA;  supplying&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;in flight&lt;/li&gt;&#xA;  &lt;li&gt;on the ground (speed below 50 knots) provided they are&#xA;  both selected auto&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That clearly states that &lt;strong&gt;both&lt;/strong&gt; push button switches need to be set to &lt;em&gt;AUTO&lt;/em&gt; in order for the DC ESS BUS to be powered from the batteries on the ground.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-15T10:20:32.660" LastActivityDate="2015-10-15T10:20:32.660" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22028" PostTypeId="2" ParentId="22019" CreationDate="2015-10-15T10:31:15.110" Score="4" Body="&lt;p&gt;Martin Baker uses (or used, it may have been retired) a modified Gloster Meteor to test ejection seats. The aircraft is piloted, with the seat being in a separate area behind the cockpit.&lt;br/&gt;&#xA;This aircraft is definitely reusable, it's been used to test ejection systems many times.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;So yes, it is possible to design an aircraft in such a way that it can be flown after an ejection of (one of) its ejection seat.&lt;br/&gt;&lt;br/&gt;&#xA;Of course in case of operational ejections these are usually done after the aircraft has sustained enough damage that it can't be flown anyway, so having it flyable after ejection isn't a high priority. And without the crew on board it becomes even less of a priority, as the crew are the ones flying it in the first place.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-10-15T10:31:15.110" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22029" PostTypeId="2" ParentId="22019" CreationDate="2015-10-15T10:39:18.583" Score="8" Body="&lt;p&gt;The first test with ejection seats were performed in 1942 in Sweden with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_17&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 17&lt;/a&gt; and in Germany in 1941 with a Junkers 87 and in 1943 with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Heinkel_He_219&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heinkel 219&lt;/a&gt; and Heinkel's pneumatic seat. Of course, then it was not the pilot who ejected but his back seater, but the aircraft did not need much modification for the tests. In each case, the pilot performed an uneventful landing after the test flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7a1pr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7a1pr.jpg&quot; alt=&quot;Saab 17 ejection sequence&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SJ1ba.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SJ1ba.jpg&quot; alt=&quot;Heinkel 219 during ejection seat trials&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Saab 17 (above, &lt;a href=&quot;http://www.deutscheluftwaffe.de/Ausrustung/Teile/Schleudersitz/He219schleudersitz.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) and Heinkel 219 (below, &lt;a href=&quot;http://www.starduststudios.com/uploads/1/8/3/4/18340833/1541985_orig.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) during ejection seat trials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To enable someone to fly the aircraft home after an ejection requires two conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The second seat must be equipped with flight controls&lt;/li&gt;&#xA;&lt;li&gt;The ejection sequencing is switched off, so the seats can be activated independently. Normally, triggering the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12823/could-someone-really-die-in-the-way-that-goose-did-in-the-movie-top-gun/12826#12826&quot;&gt;sequence&lt;/a&gt; from either seat will eject all occupants.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is exceedingly rare that both conditions are true in a modern combat aircraft. There have been a few cases where &lt;a href=&quot;https://www.youtube.com/watch?v=tPGcOSvxv5Y&quot; rel=&quot;nofollow noreferrer&quot;&gt;a crew member flew an aircraft to a successful landing&lt;/a&gt; after the pilot bailed out, but I know only a single case where the bail-out was done by ejection seat. It was a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-47_Stratojet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing B-47&lt;/a&gt;, and the &lt;a href=&quot;https://www.youtube.com/watch?v=tPGcOSvxv5Y&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube link&lt;/a&gt; is to a re-enactment of this B-47 flight in which one observer, who was also a trained pilot, took over after the crew had bailed out due to a fire in the electrical installation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read the last of the stories from &lt;a href=&quot;http://www.ejectionsite.com/estories.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt; for one accident in which everyone but the pilot ejected from an S-3 with a stuck nose wheel, and the pilot later performed a safe landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess you are concerned about the damage done by an ejection. The firing of the rockets happens in the rear part of the now very well ventilated cockpit and is a very brief event, so the flight controls and instrumentation should be in working order after an ejection. However, after the event nobody will be there to take over, and there is no way another crew member will be able to take over unless he/she has his/her own set of controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There &lt;a href=&quot;http://steveblank.com/2010/05/24/ejection-seats/&quot; rel=&quot;nofollow noreferrer&quot;&gt;have been cases of inadvertent ejection seat activations&lt;/a&gt; by mechanics on the ground. When this happens, a new ejection seat is needed, the shear pins and in most cases the canopy need replacement. After that, the cockpit area needs to be checked and cleared. But the airplane will return to service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fun fact: The &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;nofollow noreferrer&quot;&gt;XB-70&lt;/a&gt; had &lt;a href=&quot;http://www.ejectionsite.com/xb70caps.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;ejection capsules&lt;/a&gt; to make ejection at supersonic speed possible and to protect the pilots in case of pressure loss. Life support systems and a minimum set of flight controls were duplicated inside the capsule, and the pilot could continue to fly the aircraft down to a safer altitude after initiating the encapsulation sequence. Only then he would trigger the ejection.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-15T20:17:02.173" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22030" PostTypeId="1" AcceptedAnswerId="22034" CreationDate="2015-10-15T10:56:58.723" Score="0" ViewCount="7213" Body="&lt;p&gt;I tried to look for this answer but I was unable to find a complete one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the differences between &lt;strong&gt;Winglets&lt;/strong&gt;, &lt;strong&gt;Sharklets&lt;/strong&gt; (used for example on A350 XWB), and &quot;&lt;strong&gt;Blended wingtips&lt;/strong&gt;&quot; (used only on 787)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially firt two seems very similar. Anyway, more in general, what are differences/PROs/CONs of these different solutions?&lt;/p&gt;&#xA;" OwnerUserId="11089" LastActivityDate="2015-10-15T14:22:04.777" Title="Winglets vs Sharklets vs Blended wingtips" Tags="&lt;winglets&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ClosedDate="2015-10-15T12:16:40.533" ContentLicense="CC BY-SA 3.0" />
  <row Id="22031" PostTypeId="1" AcceptedAnswerId="22037" CreationDate="2015-10-15T11:12:14.627" Score="6" ViewCount="1556" Body="&lt;p&gt;Flying close to the ground is really dangerous and yet needed to land and take off. ILS is designed to keep the adequate trajectory close to the ground with (almost) no visibility. Is there a similar system for take off, e.i. a system helping pilots to maintain the adequate trajectory near the ground with almost no visibility at take off?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="1467" LastEditDate="2015-10-15T11:39:40.360" LastActivityDate="2016-07-15T01:01:48.580" Title="Is there any &quot;instrument take-off system&quot;?" Tags="&lt;takeoff&gt;&lt;instrument-flight-rules&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22033" PostTypeId="2" ParentId="22031" CreationDate="2015-10-15T11:24:32.767" Score="4" Body="&lt;p&gt;As Simon mentions, there are the Standard Instrument Departure procedures. They need not be that precise. Remember that in landing, 50 ft verctial or in lateral (left/right) deviation can easily lead to a disaster. This is not true for departure once you are airborne; 50 ft make no difference, the separation of the used routes is much much larger. Before you are airborne, you see the runway below you, and you just double-check it's the correct runway and you've got enough length of it; but neither of these directly depends on the visual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last but not least, if the runway has an ILS in your direction or the opposite one, you can use its horizontal part to navigate yourself straight out of the airport; you can't use the vertical part of course, since the desired climb angle rarely coincides with the glide slope.&lt;/p&gt;&#xA;" OwnerUserId="802" LastEditorUserId="802" LastEditDate="2016-07-15T01:01:48.580" LastActivityDate="2016-07-15T01:01:48.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22034" PostTypeId="2" ParentId="22030" CreationDate="2015-10-15T12:07:56.553" Score="2" Body="&lt;p&gt;&lt;strong&gt;Winglet advantages&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With a winglet you see a 3-5% reduction in drag which helps increase efficiency in aircraft by reducing something called a wing tip vortex which forms by the high pressure(under the wing) wraps around the top part of the wing which has the low pressure and results in a wing tip vortex. A winglet works by deflecting the air so less high pressure wraps the wing tip.&lt;/li&gt;&#xA;&lt;li&gt;Increases lift(the winglet generates lift also like an aircraft wing)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device&quot; rel=&quot;nofollow&quot;&gt;Winglet&lt;/a&gt; disadvantages&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Adds about 300 lbs of weight to the aircraft depending on the winglet&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduces maneuverability which is why you don't see a winglet on a fighter jet&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now a sharklet and a winglet are essentially the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bts: Its called a raked wing tip&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device&quot; rel=&quot;nofollow&quot;&gt;Raked wing tip&lt;/a&gt; advantages&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the same thing as a winglet by deflecting the air. With a raked wing tip you actually see a greater drag reduction than a winglet can give you which leads to great efficiency in aircraft&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Raked wing tip advantages&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You actually loose a little bit of lift due to the raked wing&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://sharklet.com/&quot; rel=&quot;nofollow&quot;&gt;Sharklet&lt;/a&gt;&lt;/strong&gt;- The sharklet deflects air just like a winglet and acts in the same way and is a winglet, but Airbus just named it differently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A350_XWB&quot; rel=&quot;nofollow&quot;&gt;A350 design&lt;/a&gt;&lt;/strong&gt;- The a350 uses a sharklet and a raked wing. You see great numbers of efficiency in the design because you include a raked wing and a sharklet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between the 3 you mentioned there is a big difference and all 3 have different advantages and disadvantages. They all act in the same way by deflecting the air the design is just different for each one. I hope this helped you understand a little bit more about these devices.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="9716" LastEditDate="2015-10-15T14:22:04.777" LastActivityDate="2015-10-15T14:22:04.777" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22035" PostTypeId="1" AcceptedAnswerId="22036" CreationDate="2015-10-15T12:10:54.743" Score="14" ViewCount="1760" Body="&lt;p&gt;This may be confirmation bias on my part, this might be impatient passengers pressing the call button, and it might be me imagining things, but it's one of those I've wondered about. I'll try to describe as best I can.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of all the times I've flown recently on an airliner, of which most of the time it's a short haul carrier often flying smaller Boeing/Airbus aircraft*, I have been aware that there is an audible chime which can be heard throughout the cabin (ie, not only when sat in the vicinity of crew seats) very soon (30-45 seconds) after take-off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is heard well before the passenger seat-belt signs are switched off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone describe what I am hearing and what its purpose is? Who is this a signal for, and who is sending the signal?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;* the two times I've flown on an Embraer I don't recall hearing it&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="13197" LastEditDate="2018-11-02T21:12:06.460" LastActivityDate="2019-08-11T14:26:15.987" Title="What is the chime that can be heard roughly 30 seconds after takeoff?" Tags="&lt;airliner&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="22036" PostTypeId="2" ParentId="22035" CreationDate="2015-10-15T12:30:48.770" Score="20" Body="&lt;p&gt;It's signalled from the cockpit (the cabin chime) to let the &lt;strong&gt;cabin crew&lt;/strong&gt; know it's OK to move around.  If you watch, this happens before the seat belt sign goes off which at the earliest, is at 10,000 feet.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-10-15T12:30:48.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22037" PostTypeId="2" ParentId="22031" CreationDate="2015-10-15T12:32:29.893" Score="6" Body="&lt;p&gt;While there is not a specific physical system dedicated to instrument departures per se, there are procedures that rely upon instrument flight rules (IFR) navigation equipment that ensure obstacle clearance when departing from an airport in instrument meteorological conditions (IMC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Information Manual&lt;/a&gt; 5-2-8.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Instrument departure procedures are preplanned instrument&#xA;  flight rule (IFR) procedures which provide&#xA;  obstruction clearance from the terminal area to the&#xA;  appropriate en route structure. There are two types of&#xA;  DPs, Obstacle Departure Procedures (ODPs), printed&#xA;  either textually or graphically, and Standard Instrument&#xA;  Departures (SIDs), always printed graphically.&#xA;  All DPs, either textual or graphic may be designed using&#xA;  either conventional or RNAV criteria. RNAV&#xA;  procedures will have RNAV printed in the title,&#xA;  e.g., SHEAD TWO DEPARTURE (RNAV). ODPs&#xA;  provide obstruction clearance via the least onerous&#xA;  route from the terminal area to the appropriate en&#xA;  route structure. ODPs are recommended for obstruction&#xA;  clearance and may be flown without ATC&#xA;  clearance unless an alternate departure procedure&#xA;  (SID or radar vector) has been specifically assigned&#xA;  by ATC. Graphic ODPs will have (OBSTACLE)&#xA;  printed in the procedure title, e.g., GEYSR THREE DEPARTURE (OBSTACLE), or, CROWN ONE&#xA;  DEPARTURE (RNAV) (OBSTACLE). Standard Instrument&#xA;  Departures are air traffic control (ATC)&#xA;  procedures printed for pilot/controller use in graphic&#xA;  form to provide obstruction clearance and a transition&#xA;  from the terminal area to the appropriate en route&#xA;  structure. SIDs are primarily designed for system enhancement&#xA;  and to reduce pilot/controller workload.&#xA;  ATC clearance must be received prior to flying a SID.&#xA;  All DPs provide the pilot with a way to depart the airport&#xA;  and transition to the en route structure safely.&#xA;  Pilots operating under 14 CFR Part 91 are strongly&#xA;  encouraged to file and fly a DP at night, during marginal&#xA;  Visual Meteorological Conditions (VMC) and&#xA;  Instrument Meteorological Conditions (IMC), when&#xA;  one is available. The following paragraphs will provide&#xA;  an overview of the DP program, why DPs are&#xA;  developed, what criteria are used, where to find them,&#xA;  how they are to be flown, and finally pilot and ATC&#xA;  responsibilities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are many details involved in actually using these procedures to make safe departures in IMC. The &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;Instrument Procedures Handbook Chapter 1&lt;/a&gt; is an excellent resource for pilots who want to review these procedures, what they provide and how to use them correctly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example of an ODP from my home airport, KCRG. There are some very tall towers less than 10 nautical miles from the airport. They are enormous and easy to avoid under visual conditions, but when IMC prevails these procedures are absolutely life-saving with such large obstructions nearby. They are taken from this &lt;a href=&quot;http://155.178.201.160/d-tpp/1511/SE3TO.PDF&quot; rel=&quot;noreferrer&quot;&gt;takeoff minimums document&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/hD0DSau.png&quot; alt=&quot;ODP&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example of a SID. These are always graphically depicted and will usually be found at larger airports. Here are pages &lt;a href=&quot;http://155.178.201.160/d-tpp/1511/00026ATLANTA.PDF&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt; and &lt;a href=&quot;http://155.178.201.160/d-tpp/1511/00026ATLANTA_C.PDF&quot; rel=&quot;noreferrer&quot;&gt;2&lt;/a&gt; of the full SID.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/Dzk8oCi.png&quot; alt=&quot;SID&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-15T12:32:29.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22038" PostTypeId="2" ParentId="22022" CreationDate="2015-10-15T13:27:58.240" Score="4" Body="&lt;p&gt;I have always been under the impression that it was mainly installed to protect the engines. However &lt;a href=&quot;http://science.nationalgeographic.com/science/space/space-panorama/gigapan-discovery-tail-cone/&quot; rel=&quot;nofollow&quot;&gt;this blurb (and cool photo)&lt;/a&gt; claim it did reduce drag. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...reduces both drag and turbulence created by the piggy-backing spacecraft while also protecting the engines&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-15T13:27:58.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22039" PostTypeId="1" CreationDate="2015-10-15T13:29:35.097" Score="3" ViewCount="1393" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/22007/5517&quot;&gt;This answer&lt;/a&gt; to &lt;a href=&quot;https://aviation.stackexchange.com/questions/22003/could-improper-deplaning-of-a-flight-with-full-fuel-tanks-cause-the-plane-to-tip&quot;&gt;the question&lt;/a&gt; about an emergency landing very early in a trans-continental flight indicated that the fuel in the aft auxiliary tanks could cause the plane to tip on its tail if the passengers weren't unloaded carefully. The cabin crew seems to have kept everyone calm and orderly, and they deplaned with no further incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question is &lt;em&gt;how&lt;/em&gt; did the orderly disembarkation prevent the plane from tipping?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the thoughts that ran through my head as I read the story:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Were the pilots busy moving fuel out of those aft tanks while the pax were deplaning?&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If so would they have started the rebalancing as soon as the firefighters cleared the plane to move? &lt;/li&gt;&#xA;&lt;li&gt;Would that have taken the hour it took to get the plane to a gate for them to shift all the fuel? &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;What else would be involved?&lt;/li&gt;&#xA;&lt;li&gt;If the fuel in the tail would cause the plane to tip, unloading the pax slowly would still leave it with an aft CG, and it would still tip once the critical number of people were off.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-15T14:30:22.453" Title="How does passenger unloading order prevent plane tipping?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;&lt;ground-operations&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22040" PostTypeId="1" CreationDate="2015-10-15T13:39:41.840" Score="6" ViewCount="1113" Body="&lt;p&gt;What is the angle of incidence of a propeller in the terminology of the Wright Brothers and how did they obtain it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Feb. 1903 (see &lt;a href=&quot;http://www.loc.gov/resource/mwright.01006/?sp=5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Screw Test 1903, page 8&lt;/a&gt;), using a 0.58 hp engine, the Wright brothers tested a propeller characterized by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Diameter, D = 8.5 ft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitch = 15 deg&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Surface, $S = 2\ ft^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RPM = 245&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They measured what appears to be the static thrust and got:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust = 18.75 lbf&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the assumption that the propeller can be modeled by a wing (Pitch = 15 deg, Surface = $2\ ft^2$, Lift = 18.75 lbf) having its entire area concentrated in a single point (called  the Center of Pressure, C.P.) traveling at RPM = 245 on a circle with the diameter 0.824 x D, $V_{wing} = RPM \times \pi \times 0.824 \times D$, the Wright brothers evaluated its Drag and from Lift, Drag and Pitch using trigonometric relations they obtained the Normal (perpendicular to the chord) and Axial or Tangential (along the chord) components of Lift + Drag (the resultant force) and some angles related to them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now comes something I do not quite understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two brothers calculated a reference force defined as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total Normal = $k \times S \times V_{wing}^2$ = 24.8 lbf,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V_{wing} = RPM \times \pi \times 0.824 \times D = 61\ \mathrm{mph}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$k =$ Smeaton’s coefficient $= 0.0033\ \mathrm{lbf} \cdot \mathrm{ft}^{-2} \cdot \mathrm{mph}^{-2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, the Wrights divided the Lift by the Total Normal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{\mathrm{Lift}}{\mathrm{Total\ Normal}} = 0.756$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and &lt;strong&gt;from this 0.756 they drew the conclusion that the angle of incidence is 7¼ deg&lt;/strong&gt;. The question is why? What is this angle of incidence and how can it be calculated?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Update&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The correspondence between the percentage 0.756 and the angle of incidence, 7¼, comes likely from a table like this (which is for a slightly different wing curvature):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Percentage of air pressure at various angles of incidence&lt;/em&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/731Kz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/731Kz.jpg&quot; alt=&quot;Percentage of air pressure at various angle of incidence&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as the propeller did not move, the incidence angle of its equivalent wing appears to be identical with the pitch of the same wing and they are not. Why?&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="2143" LastEditDate="2016-08-21T03:52:14.153" LastActivityDate="2018-01-13T14:57:27.803" Title="What is the incidence angle of a propeller in the terminology of the Wright Brothers and how did they obtain it?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;aviation-history&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22041" PostTypeId="2" ParentId="22039" CreationDate="2015-10-15T14:03:21.473" Score="1" Body="&lt;p&gt;Generally Planes are unloaded from the front to the back. In this case its likely they unloaded the aft passengers first to keep the CG forward biased. You are also assuming that they had some place to pump the fuel from the aft tanks. Since the plane diverted from Newark to Buffalo (a short hop relatively speaking) its likely the main tanks did not have enough space to allow pumping the aft tank into the mains. You would need to look over fuel burn charts for the plane to figure that out number for number someone here may have those figures for you.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-15T14:03:21.473" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22042" PostTypeId="2" ParentId="22039" CreationDate="2015-10-15T14:23:51.357" Score="2" Body="&lt;p&gt;Apparently, there have been a number of incidents with 'tail tipping' in case of Boeing 737-900s and 900ERs. In these situations, the plane 'tipping' on its tail can be prevented by two methods:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Unloading the passengers starting from rear to front.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.briansumers.com/home/2015/7/27/united-airlines-has-had-some-tail-tip-problems-with-the-boeing-737-900&quot; rel=&quot;nofollow&quot;&gt;Unloading the (baggage from) aft cargo hold&lt;/a&gt; before passengers were allowed off the aircraft. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is also &lt;a href=&quot;http://www.pprune.org/archive/index.php/t-249021.html&quot; rel=&quot;nofollow&quot;&gt;some indication&lt;/a&gt; that the 737-900s are loaded in the front rows (1-17) first followed by aft rows, while the unloading takes place in the opposite way. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-15T14:30:22.453" LastActivityDate="2015-10-15T14:30:22.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22044" PostTypeId="1" AcceptedAnswerId="22049" CreationDate="2015-10-15T15:06:37.903" Score="9" ViewCount="2606" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/22034/4197&quot;&gt;In this answer&lt;/a&gt; Ethan makes the following statement concerning winglets on fighter jets:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[Winglets] reduce maneuverability which is why you don't see a winglet on a fighter jet&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I could image that adding more weight at the end of the wings increases inertia, reducing maneuverability, but I'm not sure if this is the only reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps there is some aerodynamic phenomenon at play as well?&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="1467" LastEditDate="2018-01-22T13:03:34.127" LastActivityDate="2020-03-17T13:37:42.487" Title="Why do winglets reduce maneuverability (of fighter jets)?" Tags="&lt;aerodynamics&gt;&lt;fighter&gt;&lt;winglets&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22045" PostTypeId="1" AcceptedAnswerId="22047" CreationDate="2015-10-15T15:40:30.053" Score="13" ViewCount="91416" Body="&lt;p&gt;I was having a discussion with some friends about general aviation aircraft with cabin-class seating. We were discussing cruise speeds and there were some &quot;shop talk opinions&quot; flying around about what the fastest single-engine turboprop in general aviation is. I'm curious to know who holds the title.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="14897" LastEditDate="2018-06-16T12:29:57.137" LastActivityDate="2018-06-16T12:29:57.137" Title="What is the fastest single-engine civil turboprop aircraft with cabin seating?" Tags="&lt;aircraft-performance&gt;&lt;turboprop&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="22046" PostTypeId="2" ParentId="22045" CreationDate="2015-10-15T15:42:32.990" Score="1" Body="&lt;p&gt;The &lt;a href=&quot;http://www.evolutionaircraft.com/aircraft/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lancair Evolution&lt;/a&gt; comes to mind coming in at 300Kts &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/psRQg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/psRQg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://aerospaceblog.wordpress.com/2010/05/27/lancair-evolution/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-21&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilatus PC-21&lt;/a&gt; comes in at 370Kts but those are mainly military training planes so it may not fall under the GA space. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2017-09-01T04:29:12.913" LastActivityDate="2017-09-01T04:29:12.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22047" PostTypeId="2" ParentId="22045" CreationDate="2015-10-15T15:47:54.383" Score="12" Body="&lt;p&gt;The TBM 900 holds the title of &lt;a href=&quot;https://www.eaa.org/en/airventure/eaa-airventure-news-and-multimedia/eaa-airventure-news/eaa-airventure-oshkosh/2014-07-31-TBM_900_is_the_Worlds_Fastest_Certified_Single-engine_Turboprop&quot;&gt;fastest single engine turboprop&lt;/a&gt; for &lt;a href=&quot;http://hartzellprop.com/flying-magazine-names-fastest-aircraft/&quot;&gt;civilian planes&lt;/a&gt;. It has a top cruise speed of 330 knots at FL280.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rcxx3.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rcxx3.jpg&quot; alt=&quot;TBM 900&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-10-15T15:47:54.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22048" PostTypeId="2" ParentId="22045" CreationDate="2015-10-15T15:54:55.610" Score="13" Body="&lt;p&gt;In civil GA aircraft, &lt;a href=&quot;https://en.wikipedia.org/wiki/SOCATA_TBM&quot;&gt;TBM 900&lt;/a&gt; is the fastest one with a top cruise speed of 330 knots (at 28000 ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EOg8Q.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EOg8Q.jpg&quot; alt=&quot;TBM 900&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: flightclub.jalopnik.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if one considers &lt;a href=&quot;http://www.flyingmag.com/aircraft/fastest-aircraft-top-performers-their-class?page=0,4&quot;&gt;&lt;em&gt;all&lt;/em&gt; single engined turboprop aircraft&lt;/a&gt;, the fastest is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilatus_PC-21&quot;&gt;Pilatus PC-21&lt;/a&gt;, with a top speed of 370 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cyaie.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyaie.jpg&quot; alt=&quot;Pilatus PC 21&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Pilatus_pc-21_hb-hzc_lands_arp.jpg#/media/File:Pilatus_pc-21_hb-hzc_lands_arp.jpg&quot;&gt;Pilatus pc-21 hb-hzc lands arp&lt;/a&gt;&quot; by Adrian Pingstone (&lt;a href=&quot;//commons.wikimedia.org/wiki/User:Arpingstone&quot; title=&quot;User:Arpingstone&quot;&gt;Arpingstone&lt;/a&gt;) - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-15T15:54:55.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22049" PostTypeId="2" ParentId="22044" CreationDate="2015-10-15T15:55:03.283" Score="12" Body="&lt;p&gt;Your observation about roll inertia is correct: Winglets add proportionally more roll inertia for their small increase in L/D, and this increase exists only for the higher range of lift coefficients. At low lift coefficients (think cruise), when the induced drag is low, they add more friction drag and reduce the L/D overall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three aspects to maneuverability:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How quickly can you accelerate into a roll? Here the added inertia of winglets reduces roll acceleration&lt;/li&gt;&#xA;&lt;li&gt;How high is the maximum sustained turn rate? This is determined by the maximum lift at zero sink rate, and here winglets are helping. Especially when mounted to low aspect ratio wings.&lt;/li&gt;&#xA;&lt;li&gt;How high is the maximum turn rate? Now only lift counts, and the increased drag is compensated by an increased sink rate. Again, winglets help a little, but less than with the sustained turn rate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now look at the time any fighter will spend around 1g (hint: Something close to 100%) and how much is spent at high lift coefficients, like when turning tightly in air combat. Winglets would help in the turn (and I think Ethan's opinion is wrong), but be a source of drag for the rest of the mission. Adding winglets would require to increase the fuel volume to prevent a reduction in flight time and range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, winglets are only used on highly loaded, high-aspect ratio wings when their L/D at a rather high lift coefficient needs to be pushed up even more. Highly maneuverable configurations are less concerned with single-percentage increases in L/D for a small part of the flight, and in order to improve turn performance, increasing wing span is much more effective. But that increases roll inertia and roll damping, so fighters use low-aspect ratio wings and compensate their higher drag in a turn with more powerful engines. Note that the trend in fighter aspect ratios went down with the improving thrust-to-weight ratio of jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that is the reason why you don't see winglets on fighter jets: They would lower L/D for most of the flight. To perform the same mission, the fighter without winglets can be made smaller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But let's make no mistake: Low aspect ratio configurations gain the most from winglets: They were essential on the &lt;a href=&quot;https://falsesteps.wordpress.com/2012/12/02/hermes-the-european-spaceplane/&quot;&gt;Hermes re-entry vehicle project&lt;/a&gt; to give it enough L/D for a successful flare.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-15T16:04:55.417" LastActivityDate="2015-10-15T16:04:55.417" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22050" PostTypeId="2" ParentId="22044" CreationDate="2015-10-15T16:27:57.407" Score="7" Body="&lt;p&gt;The effects of winglets on the maneuverability of aircraft is not straightforward, with different effects on various maneuverability parameters.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In the simplest sense, the winglets have the effect of increasing the aspect ratio of the wing. This results in lower roll angular acceleration as a higher moment of inertia needs to be overcome before the movement begins.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The roll rate (at maximum aileron deflection) is slightly greater with winglets, as they increase the local span loading near the wing tips, thereby augmenting aileron effectiveness. This means that smaller aileron deflections are required for a given rolling moment; meaning less drag for a given roll rate and a higher maximum roll rate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the winglets increase the L/D ratio, the climb performance is improved.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are other reasons for the absence of winglets in combat aircraft, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Winglets are optimized for a particular configuration of wing, flight speed and profile and are usually ineffective, and may even have adverse effects on aircraft performance in other situations. For example, the winglet increases profile drag while reducing induced drag; in conditions where profile drag is a major contributor to the total drag, this is a disadvantage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The winglets will have disastrous effect in supersonic flight due to the added drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The thin winglets are prone to flutter problems.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Winglets will add considerably to the radar signature from the most critical angles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-15T16:46:17.520" LastActivityDate="2015-10-15T16:46:17.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22052" PostTypeId="1" CreationDate="2015-10-15T17:38:32.877" Score="23" ViewCount="2694" Body="&lt;p&gt;One of the inherent risks in flying an aircraft is a controlled flight into terrain (CFIT) incident. CFIT occurs when a flight impacts terrain while under positive control. Aside from incidents of suicide, this means the terrain impact came as a surprise to the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controlled Flight Into Terrain Awareness is a special emphasis area in the Federal Aviation Administration's (FAA) practical test standards (PTS). The FAA felt it necessary to include this as a special emphasis area because of the prevalence of this type of incident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What steps can pilots take to mitigate the risk of CFIT?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-16T00:12:31.717" LastActivityDate="2015-10-16T09:34:55.547" Title="What steps can pilots take to mitigate the risk of controlled flight into terrain (CFIT)?" Tags="&lt;safety&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22054" PostTypeId="2" ParentId="22052" CreationDate="2015-10-15T18:01:04.537" Score="20" Body="&lt;p&gt;There are a few things you can do to help mitigate it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Get An Instrument Rating&lt;/strong&gt;: Some CFIT accidents happen during a nasty mix of mountain flying, scud running and an inevitable flight into IMC, which ends with hitting the side of a mountain, an instrument rating here can be a truly valuable thing in these situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Plan Your Routes and Minimums Carefully&lt;/strong&gt;: This takes place in the preflight and you should always check your charts for minimum altitudes as well as man made obstructions that may be in your flight path. Once you have your minimum altitude selected, stick to it. If weather does not permit that altitude either alter your course or scrub the flight. There is some good info from &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2004/July/1/Terrain-Avoidance-Plan-TAP-br&quot; rel=&quot;noreferrer&quot;&gt;AOPA on it here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/l4IIQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l4IIQ.jpg&quot; alt=&quot;Chart showing minimum altitude&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Synthetic Vision&lt;/strong&gt;: Apps like &lt;a href=&quot;http://foreflight.com/&quot; rel=&quot;noreferrer&quot;&gt;ForeFlight&lt;/a&gt; are quickly becoming common place in aviation as are glass cockpits, and these have proven invaluable in terms of terrain awareness and avoidance as many of them now include synthetic vision with terrain maps. Good preflighting is still key and you should always inform your self of all potential terrain before a flight, while technology can aid in avoidance you should always have a backup plan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Avoid The Mountains&lt;/strong&gt;: This is sometimes not an option but if you as the PIC feel uncomfortable you should always choose a route around terrain if possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Practice Mountain Flying&lt;/strong&gt;: Just as you would with any other aspect of aviation you can always get an instructor and practice mountain flying. The FAA has &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/tips_on_mountain_flying.pdf&quot; rel=&quot;noreferrer&quot;&gt;some tips here&lt;/a&gt; but mountain flying carries its own risks and unique cases that you should be ready for. Mountains can have turbulent airflow and you should make an effort to understand how wind flows over them, you can find a &lt;a href=&quot;http://www.blincmagazine.com/forum/showthread.php?t=67138&quot; rel=&quot;noreferrer&quot;&gt;discussion on it here&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vo6wF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vo6wF.jpg&quot; alt=&quot;Risk of turbulence associated with mountain flying&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Get a FIS-B Weather Receiver&lt;/strong&gt;: As mentioned above winds can be important when flying. It's worth it to have an &lt;a href=&quot;https://www.foreflight.com/products/stratus/&quot; rel=&quot;noreferrer&quot;&gt;FIS-B weather&lt;/a&gt; in receiver so that you always have the most up to date information. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="19" LastEditDate="2015-10-15T21:38:59.723" LastActivityDate="2015-10-15T21:38:59.723" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22055" PostTypeId="2" ParentId="22052" CreationDate="2015-10-15T18:26:14.773" Score="13" Body="&lt;p&gt;OK, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/22052/what-steps-can-aircraft-pilots-take-to-mitigate-the-risk-of-controlled-flight-in#comment50286_22052&quot;&gt;my rather flippant comment&lt;/a&gt; aside, avoiding controlled flight into terrain is largely an exercise in common sense (many FAA &quot;Special Emphasis Areas&quot; could be rolled up into a special emphasis on common sense).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It basically boils down to three things:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Knowing where the terrain / obstacles are.&lt;/li&gt;&#xA;&lt;li&gt;Knowing where your aircraft is.&lt;/li&gt;&#xA;&lt;li&gt;Ensuring your aircraft doesn't get too close to terrain or obstacles.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So how do we do that?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Charts and Elevation Figures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For many pilots there's a simple and practical way to do this printed right on your VFR sectional chart: The Maximum Elevation Figure (MEF):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/lUvDN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lUvDN.jpg&quot; alt=&quot;Maximum Elevation Figure&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;The MEF indicates the tallest feature (terrain or obstacle) in a given quadrangle on the sectional. If you are flying with a healthy margin (500-1000 feet or more) between you and the Maximum Elevation Figure you will not hit terrain or obstacles - they will be below you. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The MEF is one reason charts expire: As new obstacles are constructed (buildings, radio towers, etc.) the MEF in each quadrangle will be updated appropriately. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;ATC Information (and More Charts)&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;ATC deals with an altitude which is useful for all pilots to know: Minimum Instrument Altitude (MIA). This altitude provides a guaranteed obstacle/terrain clearance (1,000 feet, or 2,000 feet in designated mountainous areas) for instrument flights.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Operating at or above the Minimum Instrument Altitude for a region gives you similar protections to operating at or above the MEF altitude from the VFR sectional, and also usually ensures that ATC will have radar contact with you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Minimum Instrument Altitude (and another useful one, the Minimum Vectoring Altitude) are charted for center and TRACON facilities. Most pilots haven't ever seen these charts (they're &quot;Not For Navigation&quot; and not particularly useful unless you know the ground over which the sectors are drawn), but &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/mva_mia/&quot; rel=&quot;nofollow noreferrer&quot;&gt;they are available from the FAA&lt;/a&gt; as supplemental information.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Aircraft Performance and Common Sense&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Unfortunately some pilots don't have the option of flying &lt;em&gt;over&lt;/em&gt; all the terrain they may have to deal with - pilots in mountainous areas have to use mountain passes to cross ridges, and may be flying between peaks that are above their altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's here that common sense and aircraft performance play into things: You know your aircraft has a given rate of climb given its current altitude and loading, and that terrain is rising at a given slope below you.  It is then the pilot's responsibility to ensure that they can out-climb the terrain, and to ensure that there is an &quot;out&quot; (either another pass to divert to or enough room to safely make a 180-degree turn if the terrain is out-climbing the aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This applies for man-made obstacles as well as terrain - &lt;a href=&quot;https://en.wikipedia.org/wiki/2006_New_York_City_plane_crash&quot; rel=&quot;nofollow noreferrer&quot;&gt;misjudging the turning radius of your aircraft in flight can be fatal if you're relying on that to get you out of trouble&lt;/a&gt;.&lt;br&gt;&#xA;Common sense dictates that you don't enter a pass (either a canyon/valley or a corridor surrounded by tall buildings) unless you know you can safely fly through or turn around.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Fancy Electronic Tools&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Electronic flight planning applications have made terrain avoidance much easier: programs like ForeFlight and Garmin Pilot include &quot;Hazard Advisor&quot; and &quot;Altitude Advisor&quot; functions that will show where your planned route will intersect terrain or obstacles.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/UWZIs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UWZIs.png&quot; alt=&quot;ForeFlight - Hazard Advisor / Altitude Advisor&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many electronic flight bag / flight planning programs also include limited synthetic vision capabilities, and some glass-cockpit aircraft also include these capabilities. The virtual terrain presentation available using synthetic vision systems can be helpful if flying in IMC or marginal VFR weather:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3eiLi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3eiLim.jpg&quot; alt=&quot;Foreflight Hazard Advisor &amp;amp; Synthetic Vision&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/ueJgh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ueJghm.jpg&quot; alt=&quot;Garmin Synthetic Vision&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-15T18:26:14.773" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22056" PostTypeId="2" ParentId="673" CreationDate="2015-10-15T19:31:04.263" Score="1" Body="&lt;p&gt;There is a term called Tg, glass transition temperature. In PC this is around 150C. Therefore the mobility in the PC molecular chains at RT are unmobile, which in most amorphous polymers would cause them to be brittle. However due to the chemical bonding of PC this does not occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, upon an impact, the stress energy resulting from a certain point will be transferred across many of the Polycarbonate chains. Induced impacts can cause large amounts of stress, especially at the speeds we are talking about. Therefore the holes are not only there as people have already said, for the equalisation of pressure differences, but it also a stress relieving point for the material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources: I am a MEng Materials Engineer with experience in this field&lt;/p&gt;&#xA;" OwnerUserId="11798" LastActivityDate="2015-10-15T19:31:04.263" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22057" PostTypeId="1" CreationDate="2015-10-15T19:41:52.827" Score="4" ViewCount="431" Body="&lt;p&gt;Has anyone ever heard of a geared turbofan in which the axis of rotation of the fan is offset from (i.e. not the same as) the axis of rotation of the turbine? In all the current geared turbofans I've encountered, the input shaft from the turbine to the gearbox is co-axial with the output shaft to the fan.&lt;/p&gt;&#xA;" OwnerUserId="11799" LastEditorUserId="6886" LastEditDate="2015-10-15T19:59:20.587" LastActivityDate="2015-10-16T20:56:06.327" Title="Off-center fan in geared turbofan - does this exist?" Tags="&lt;turbofan&gt;&lt;geared-turbofan&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22060" PostTypeId="2" ParentId="17439" CreationDate="2015-10-15T22:35:41.453" Score="0" Body="&lt;p&gt;They know the debris is from a 777 because the parts have part numbers on them which are unique to that model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since all other 777s are accounted for and no other 777s have crashed in the Indian Ocean, the flaperon ccould only be from MH370.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-10-15T22:35:41.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22061" PostTypeId="1" AcceptedAnswerId="22063" CreationDate="2015-10-15T23:07:35.610" Score="3" ViewCount="1036" Body="&lt;p&gt;I have been doing a lot of reading into IFR navigation, and have been looking at the various instruments and systems that are used.  I am going to exclude GPS here, as I have been focussing on some of the more 'old-school' methods.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, if a private pilot decided to fly their GA aircraft from A to B, lets say a distance of 500nm, what IFR systems would they use to navigate? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My first answer myself would be VOR, but the range seems to be a limiting factor.  For example, high altitude VORs have a maximum range of roughly 130nm (&lt;a href=&quot;http://flighttraining.aopa.org/magazine/2000/December/200012_Features_The_ABCs_Of_VORs.html&quot; rel=&quot;nofollow&quot;&gt;http://flighttraining.aopa.org/magazine/2000/December/200012_Features_The_ABCs_Of_VORs.html&lt;/a&gt;).  If we were flying between two major cities, this wouldn't be an issue, as I would expect plenty of stations to track to on the way, but what if I was flying between two airports where the VOR stations were positioned 300nm apart?  Is this sort of IFR navigation only possible with GPS?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance.&lt;/p&gt;&#xA;" OwnerUserId="8476" LastActivityDate="2015-10-16T07:29:57.207" Title="What is the primary means of IFR navigation for private pilots?" Tags="&lt;navigation&gt;&lt;instrument-flight-rules&gt;&lt;vor&gt;&lt;ifr-navigation&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22062" PostTypeId="2" ParentId="22061" CreationDate="2015-10-15T23:15:19.557" Score="1" Body="&lt;p&gt;You can use Automatic Direction Finder (ADF) along with Non Directional Beacon (NDB).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, VOR/DME, GPS/GNSS and radar (by ATC) can also be used.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-15T23:15:19.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22063" PostTypeId="2" ParentId="22061" CreationDate="2015-10-15T23:42:14.113" Score="6" Body="&lt;p&gt;There are numerous options, and it depends highly on your route. But there are generally enough VORs scattered across the country such that you should be in range of a couple of them pretty much everywhere. As mentioned in another answer, there are NDBs, but in the continental US, generally, the ones not on an approach are getting fewer, as the FAA has followed a path of not repair them once they break. Other parts of the world, still use them and there are also NDB based airways(AIM has examples for how they can be charted on US charts).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you had to plan a  flight from a field that doesn't have a navigational fix, and you don't have GPS, you'd start by looking for airways near where you are. Once you find some that go in the general direction you want to go, you start figuring out intersections near that or how you plan to intercept the airway. Then you end up most likely planning a zig-zag course following airways towards your destination.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-10-15T23:42:14.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22064" PostTypeId="2" ParentId="13600" CreationDate="2015-10-16T00:09:50.843" Score="2" Body="&lt;p&gt;Small arms fire absolutely can take down aircraft: &lt;a href=&quot;http://www.lonesentry.com/articles/defga/&quot; rel=&quot;nofollow&quot;&gt;http://www.lonesentry.com/articles/defga/&lt;/a&gt; (WW2)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In one instance in Africa, an eye-witness reported the destruction of three Italian planes in 5 minutes by small-arms fire. In another case, the Germans claim to have brought down a Soviet plane with an automatic pistol. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://fas.org/man/eprint/sad.pdf&quot; rel=&quot;nofollow&quot;&gt;United States Army Air Defense Artillery School &quot;Small Arms Defense&quot;&lt;/a&gt; describes tactical doctrine: saturate the region in front of the plane aircraft with lead and hope that enough hits are made to critically damage it.&lt;/p&gt;&#xA;" OwnerUserId="7776" LastActivityDate="2015-10-16T00:09:50.843" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22065" PostTypeId="2" ParentId="13600" CreationDate="2015-10-16T00:59:22.300" Score="0" Body="&lt;p&gt;If the bullet is able to damage a tire, such that chunks of the tire fly off, those chunks could cause even more damage than just the bullet alone.  That was enough to bring down a Concorde (Flight 4590).&lt;/p&gt;&#xA;" OwnerUserId="11802" LastActivityDate="2015-10-16T00:59:22.300" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22066" PostTypeId="2" ParentId="22019" CreationDate="2015-10-16T02:48:15.180" Score="2" Body="&lt;p&gt;There was a case when Soviet MiG-23 was flying for more than 500 miles after ejection of pilot.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/1989_Belgian_MiG-23_crash&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/1989_Belgian_MiG-23_crash&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11805" LastEditorUserId="5517" LastEditDate="2015-10-16T12:51:10.163" LastActivityDate="2015-10-16T12:51:10.163" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22067" PostTypeId="1" CreationDate="2015-10-16T06:04:38.463" Score="14" ViewCount="5237" Body="&lt;p&gt;Every time before landing or take off, the cabin crews continuously remind passengers to pull up the window shades, straighten their seats and what not. My question is why can't pilots be given control of these things, at a flick of a button they can open / close all window shades and upright all seats. It's 2015 not 1980.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1678" LastEditDate="2015-10-16T10:05:04.180" LastActivityDate="2015-10-16T12:37:03.027" Title="Why don't pilots control window shades &amp; seat recliners?" Tags="&lt;cabin-design&gt;" AnswerCount="4" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22068" PostTypeId="2" ParentId="22067" CreationDate="2015-10-16T06:15:02.177" Score="50" Body="&lt;p&gt;Adding all those actuators and associated wiring will add weight and cost to each flight, but the cabin crew have to be there for safety reasons, so they may as well have something to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides, how would you feel if your seat suddenly jolted you upright without warning?&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-16T06:15:02.177" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22069" PostTypeId="2" ParentId="22061" CreationDate="2015-10-16T07:29:57.207" Score="4" Body="&lt;p&gt;In the UK I generally use VORs where possible, then NDBs, then good old dead reckoning. GPS spoils the fun!... and besides the planes I regularly hire are at a flight school and each has a different GPS installed (or in one case no GPS at all). You &quot;program&quot; a VOR radio in pretty much the same way in all planes (or at least all of the ones I fly), but I reckon trying to remember what random combination of buttons, twists and presses I need to enter a route on each system is far more likely to end in a mistake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example to get from my local field to our nearest GA-friendly airport with an ILS is 2 VORs then an NDB (located at the ILS airport, and forms part of the procedural ILS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I only use for dead reckoning for short legs, like getting through gaps in airspace around London - e.g. track outbound on from VOR to 8DME, then heading x for 7 minutes, then heading y until you intercept the z track onto an NDB]. I guess if you're in an area with very sparse VOR coverage you probably have less airspace issues, so less need for accuracy (terrain issues notwithstanding - but the higher you are the further the reception). In that case longer-distance dead-reckoning may get you between VORs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also have an app on my iphone which warns if I'm about to bust controlled airspace, but that breaches your &quot;no GPS&quot; question :).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically you can use &quot;VDF&quot; too in the UK (i.e. some airports can tell you your bearing from radio transmissions), although I've not tried that myself.&lt;/p&gt;&#xA;" OwnerUserId="11809" LastActivityDate="2015-10-16T07:29:57.207" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22070" PostTypeId="2" ParentId="22067" CreationDate="2015-10-16T08:53:59.203" Score="28" Body="&lt;p&gt;Adding to @Airsick's answer there's an important psychological component, which is the illusion of control. Passengers in an airplane have very little they have control of, they are told when they can go to the bathroom and when they have to stay in their seat, they are given their meals rather than choosing when to eat, etc. Passengers have the option to control seat position, tray tables, shades, lights, and entertainment systems to suit their comfort. These things are important as they make people feel better about being shut up in an aluminum tube for hours, even if they make no ultimate difference as to what happens. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you take control of these things away people would feel they are an intrusion into their personal space, and would not like it at all. People like doing things themselves, even if they have no choice ultimately. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-10-16T08:53:59.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22072" PostTypeId="2" ParentId="22067" CreationDate="2015-10-16T09:02:23.850" Score="33" Body="&lt;p&gt;On the Boeing 787, the mechanical window shades have been replaced with glass panes which can be made more opaque or transparent by applying electric current to them. &lt;a href=&quot;http://gizmodo.com/5829395/how-boeings-magical-787-dreamliner-windows-work&quot;&gt;(source)&lt;/a&gt; The passengers can control their own window's opacity through buttons, but the cabin purser can also control them centrally. &lt;/p&gt;&#xA;" OwnerUserId="1478" LastActivityDate="2015-10-16T09:02:23.850" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22073" PostTypeId="2" ParentId="22052" CreationDate="2015-10-16T09:34:55.547" Score="6" Body="&lt;p&gt;The most important thing for the safety of any flight happens before you leave the ground, and that is &lt;strong&gt;planning&lt;/strong&gt;. Know your route, have contingencies, and set limits on deviations. Set conditions on when you will abandon your plans and turn back, and stick to them regardless of peer pressure. Try making a good decision while you're being bounced around in turbulence, the visibility is rapidly worsening, and you have a bunch of people who know nothing about flying telling you to just go for it and you'll see why it is better to have a plan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many CFIT accidents happen because pilots fly into poor weather and elect to go on rather than turn back, which is sometimes called get-there-itis. You've flown 2 hours and the destination is only 30 minutes ahead, surely this cloud bank is only a mile or two thick and I'm instrument rated. Oops - where'd that mountain come from?! Flying through clouds is not safe without planning, even if with an instrument rating. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other accidents happen because pilots decide to fly below weather. The weather keeps getting lower so they go lower until they are too low to avoid terrain. They didn't set a limit on how low the weather has to get before they turn back, or if they set a limit they don't stick to it because of wishful thinking or get-there-itis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the fancy tools in the world are no substitute for a map and good planning. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-10-16T09:34:55.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22074" PostTypeId="1" AcceptedAnswerId="22363" CreationDate="2015-10-16T10:55:35.733" Score="5" ViewCount="882" Body="&lt;p&gt;Wikipedia's article on the &lt;a href=&quot;http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15&quot; rel=&quot;nofollow&quot;&gt;MiG-15&lt;/a&gt; only states a basic number of 12,000 produced natively, with up to 6,000 more produced in other countries. But it does not list any years for this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When did mass-production start and end for the MiG-15 in the Soviet Union? This would at least let us divide 12,000 by the total years to get an average production rate. Ideally I'm looking for the number built each year, as this will surely vary year to year.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="22726" LastEditDate="2019-09-12T21:04:00.150" LastActivityDate="2019-09-12T21:04:00.150" Title="What was the yearly number of MiG-15's produced?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;aircraft-manufacturer&gt;&lt;mig-15-17&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22076" PostTypeId="2" ParentId="22057" CreationDate="2015-10-16T12:36:38.130" Score="3" Body="&lt;p&gt;There are no off-centered turbofan engines in service today. However, United Technologies Corporation (UTC), has patented an engine with an angled core (Pratt &amp;amp; Whitney is a part of UTC).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RqZ1r.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RqZ1r.png&quot; alt=&quot;Angled Engine&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from US patent &lt;em&gt;Gas turbine engine with separate core and propulsion unit&#xA;US 8789354 B2&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air from the fan is ducted around the side and back of the core to enter from the opposite direction. The hot gas will be discharged forward through a power (low-pressure) turbine connected to the fan via a gear system. The turbine, gearbox and fan will be connected through a short shaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LdUAq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LdUAq.jpg&quot; alt=&quot;Angled engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: aviationweek.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design is expected to have some advantages due the unconventional layout adopted, like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;As the core and fan are separate, core can be easily removed for maintenance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the compressors (in cores) are at an angle to each other, the possibility that uncontained failure in one engine will damage another engine is reduced (when the engines are installed in the &lt;a href=&quot;https://www.nasa.gov/content/the-double-bubble-d8-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;double bubble D8&lt;/a&gt; configuration)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-16T12:36:38.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22077" PostTypeId="2" ParentId="22067" CreationDate="2015-10-16T12:37:03.027" Score="2" Body="&lt;p&gt;It would also be something else to cause a flight to be cancelled.  If the window blind system failed and the blinds couldn't be operated manually then the aircraft would be grounded.&lt;/p&gt;&#xA;" OwnerUserId="11817" LastActivityDate="2015-10-16T12:37:03.027" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="22078" PostTypeId="1" AcceptedAnswerId="22092" CreationDate="2015-10-16T13:02:40.587" Score="16" ViewCount="3716" Body="&lt;p&gt;An unmanned aerial vehicle (UAV) was shot down by Turkish aircraft, which made me wonder, whether the Turkish pilots faced any defending moves from the UAV, or once they found it, taking down was a piece of cake?&lt;/p&gt;&#xA;" OwnerUserId="8887" LastEditorUserId="3386" LastEditDate="2018-04-21T14:35:49.667" LastActivityDate="2018-12-26T07:45:27.607" Title="Can a UAV defend itself?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;unmanned-aerial-vehicle&gt;&lt;dogfighting&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22080" PostTypeId="2" ParentId="22078" CreationDate="2015-10-16T13:42:31.250" Score="12" Body="&lt;p&gt;&lt;em&gt;Can a UAV defend itself?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were attempts to install defense systems on drones but such weapons have not proved effective, at least up to Nov. 2012 (see the article below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;em&gt;In 2002 the Air Force fitted some of its early-model Predator drones with short-range Stinger air-to-air missiles. But even with the right weaponry the robots were likely a poor match for enemy fighters, and the Air Force ultimately stripped them of the missiles.&#xA;...&#xA;The one instance of an air-to-air-armed Predator fighting back against an attacking aircraft resulted in the drone’s destruction.&lt;/em&gt;&quot;, Source: &lt;a href=&quot;http://www.wired.com/2012/11/predator-defenseless/&quot;&gt;Predator Drones Once Shot Back at Jets…, authour: DAVID AXE, 11.09.12&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-16T13:54:03.930" LastActivityDate="2015-10-16T13:54:03.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22081" PostTypeId="2" ParentId="22078" CreationDate="2015-10-16T13:43:37.293" Score="11" Body="&lt;p&gt;Short answer: No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drone needs sensors, and if the designers were preoccupied with outfitting it for its main mission and did not include anything to detect an incoming threat, a drone is a sitting duck. But even with complete situational awareness it still is close to a sitting duck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with sensors onboard, the options are limited. If you have IR sensors which can spot the cooled IR seeker of an incoming missile, the drone can throw out flares and hope to confuse the missile seeker. However, modern missiles don't go for the hottest target in the sky, but can use the flares to better find their source. This is called &quot;climbing up the stairs&quot; in the vernacular of missile engineers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propeller driven drones are a difficult target for IR seekers which are optimized for the hot section of a jet exhaust, so the chances of being hit by an IR guided missile are low. Therefore, it makes sense not to include anti-IR measures - they cost weight and money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the threat is another aircraft, radar helps. But putting a radar transmitter on a drone will make it advertise its presence to all suitably tuned receivers. Better to use passive detection, then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be optical or IR sensors which scan the sky and look for rapidly moving patterns. Once found, the drone can fly evasive maneuvers to get away from the threat. But since it is optimized to loiter in a target area, its lift and thrust reserves are most likely much smaller than those of a fighter aircraft. Consequently, maneuvering will only delay the inevitable contact with the enemy. And since the enemy can maneuver faster, he will be first to be able to shoot a missile or a salvo from his gun. Therefore, adding a missile to the drone will also not help. Without onboard radar, this can only be a short-range IR missile, and this needs to be pointed in the right direction before launch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, the drone will not benefit much from detecting a threat. Yes, it can transmit footage of the enemy closing in, which might help in identifying what happened and could be used in a political dispute, but then drones are built for flying where you don't want to send manned aircraft, so the value of that footage is most likely limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the price you pay for using low-cost drones instead of fully developed combat aircraft. Once the drone is detected, a determined adversary has little problem taking it out.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-17T04:28:04.357" LastActivityDate="2015-10-17T04:28:04.357" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22083" PostTypeId="1" AcceptedAnswerId="22102" CreationDate="2015-10-16T13:59:44.447" Score="15" ViewCount="677" Body="&lt;p&gt;In addition to passenger flight and charter flight, Concorde has been used for astronomical observations, including &lt;a href=&quot;http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-82-5105&quot; rel=&quot;noreferrer&quot;&gt;the longest solar eclipse observation on 30th June 1973&lt;/a&gt;(PDF) and &lt;a href=&quot;http://articles.sun-sentinel.com/1986-03-16/news/8601160604_1_air-france-concorde-british-airways-concorde-two-concorde&quot; rel=&quot;noreferrer&quot;&gt;observation of Halley's Comet on April 1986.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;How was Concorde modified for astronomical observations?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How is safety ensured with equipment installed when flying at supersonic speed and at 60,000 feet?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="1696" LastEditDate="2015-10-16T20:51:42.477" LastActivityDate="2015-10-16T20:51:42.477" Title="How were astronomical observations performed from Concorde?" Tags="&lt;concorde&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22085" PostTypeId="1" AcceptedAnswerId="22088" CreationDate="2015-10-16T14:04:41.187" Score="38" ViewCount="6029" Body="&lt;p&gt;Randall Munroe (author of XKCD and What If), once wrote a What If about how fast one would have to drive a car in order to have &lt;a href=&quot;http://what-if.xkcd.com/93/&quot;&gt;rain water shatter the windshield&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the post he mentions that water hitting a windshield at supersonic speeds has the &lt;em&gt;potential&lt;/em&gt; to shatter the glass.**&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The article, unfortunately, is only talking about automobile glass.  And while I'm sure it's true that automobile glass would shatter if rain hit it at super sonic speeds, it's pretty clear to me that the glass on supersonic aircraft is not shattering when it flies through precipitation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what is done to a super sonic aircraft's windshield to keep it from shattering when flying through precipitation?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;** &lt;em&gt;Here's a block quote of all the pertinent text in the post from Munroe.  I figured I'd post it for those who are Too Lazy™ to go read the article.  (Though, honestly, you ought to.  It's informative and entertaining.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Here's what happens when a raindrop hits a glass surface at high speed:&#xA;  When the droplet makes contact with the surface, a shockwave travels back up through the droplet...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...Normally, this shockwave would move at the speed of sound within the liquid—about 1300 m/s, four times faster than in air. However, at high impact speeds, this shockwave actually moves substantially faster than the speed of sound in water.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The water is squeezed between the incoming drop and the glass surface, which makes it squirt sideways in all directions. These jets of water can move even faster than the original (already supersonic) droplet, and even faster than the shockwaves we mentioned...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...The sharp pulse from the shockwave can crack glass...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...In addition to the direct downward pressure, the water jetting sideways can cause damage, too. If the material has any microscopic holes, cracks, or bumps, those jets can strike them and create new cracks or widen existing ones.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;source&lt;/em&gt;: &lt;a href=&quot;http://what-if.xkcd.com/93/&quot;&gt;What If #93&lt;/a&gt;, Randall Munroe&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="511" LastEditorUserId="1696" LastEditDate="2016-07-05T19:42:41.463" LastActivityDate="2016-09-27T23:01:40.937" Title="How do aircraft windshields not crack when flying at supersonic speeds through precipitation?" Tags="&lt;weather&gt;&lt;windows&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22086" PostTypeId="1" AcceptedAnswerId="22168" CreationDate="2015-10-16T14:32:32.560" Score="11" ViewCount="19925" Body="&lt;p&gt;Is there a place where past METARs are logged?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose I want all the METAR for a given airport from October 1st to October 15th 2015. Where can I find them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it matters, I'm looking in particular for METARs from French airports. &lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2020-12-04T18:22:30.333" Title="Where can I get a history of METARs?" Tags="&lt;datasets&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ClosedDate="2015-10-19T19:11:20.827" ContentLicense="CC BY-SA 3.0" />
  <row Id="22087" PostTypeId="1" AcceptedAnswerId="22091" CreationDate="2015-10-16T14:33:29.230" Score="16" ViewCount="2548" Body="&lt;p&gt;Most aircraft maintain longitudinal stability by balancing three forces:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The down force acting through the center of gravity (CG)&lt;/li&gt;&#xA;&lt;li&gt;The lifting force acting through the center of lift&lt;/li&gt;&#xA;&lt;li&gt;The down force acting through the center of pressure on the horizontal stabilizer.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pgyAm.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pgyAm.png&quot; alt=&quot;Forces of flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, what are some aircraft designs that deviate from this basic principle? Are there aircraft we see all the time that don't work this way? As a side note, how would weight and balance be affected if this principle isn't used?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="34686" LastEditDate="2020-04-04T15:42:49.227" LastActivityDate="2020-04-04T17:57:24.567" Title="Do any airplane designs exist that don't involve a flight surface that provides downforce?" Tags="&lt;aircraft-design&gt;&lt;aircraft-physics&gt;&lt;stability&gt;&lt;flight-dynamics&gt;&lt;flight-mechanics&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22088" PostTypeId="2" ParentId="22085" CreationDate="2015-10-16T14:34:38.483" Score="38" Body="&lt;p&gt;The Concorde had &lt;a href=&quot;http://www.concordesst.com/nose.html&quot;&gt;2 discrete windshields&lt;/a&gt; for different stages of flight. During subsonic flight (mainly take off and landing) the nose was drooped and the inner windshield was exposed. For supersonic flight the Concorde would raise its drop nose which also contained an outer windshield that would cover the inner windows. This outer windshield was made of special heat resistant glass that was also tinted. It can be assumed that this outer windshield could also withstand any pressure exerted during supersonic flight. The bigger problem in the Concorde was heat: the nose had to have fuel pumped through it just to keep it cool enough. For what it's worth the Concorde flew at about 50,000ft when it was supersonic; this is well above most weather systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drooped&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9wRMM.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9wRMM.jpg&quot; alt=&quot;Nose in lower position&quot;&gt;&lt;/a&gt; &#xA;&lt;br&gt;&lt;sub&gt;(&lt;a href=&quot;http://www.concordesst.com/nose.html&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Place &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Js0DA.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Js0DA.jpg&quot; alt=&quot;Nose in upper position&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sub&gt;(&lt;a href=&quot;http://www.concordesst.com/nose.html&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested, there is an &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/p003228.pdf&quot;&gt;old paper you can find here&lt;/a&gt; that covers windshield failures and lists the Concorde as the #2 aircraft for it (747 comes in at #1) over the years the paper covers. Interestingly enough here is a table of causes:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WfYi4.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WfYi4.png&quot; alt=&quot;Table of causes for windshield failures&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heat fatigue and manufacturing defects (what I assume they mean by saying the windshield itself is the issue) are the primary cause of the issue according to this data. Here is &lt;a href=&quot;http://www.google.com/patents/US3477667&quot;&gt;one of the patents filed&lt;/a&gt; for what appears to be the Concorde windshield; it's an interesting read!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going further, if we look at the most extreme case of supersonic planes, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot;&gt;SR-71 Blackbird&lt;/a&gt;, the inside of the windshield was in excess of 120&amp;deg;C and the exterior of the nose area would be closer to 260&amp;deg;C during supersonic flight. This would turn any water into vapor if it came into contact with the surface. While I don't know the specifics of that, the Blackbird flew at close to 80,000ft, so it too was above most (if not all) weather. I can't yet find an official quote of what that windshield was made of, but heat was still a larger issue than hitting rain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T7hLd.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T7hLd.jpg&quot; alt=&quot;Diagram of in-flight surface temperatures of SR-71&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sub&gt;(&lt;a href=&quot;http://www.migflug.com/jetflights/remarkable-airplanes-of-the-world-part-1-the-fastest.html&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aem.umn.edu/people/faculty/joseph/archive/docs0/96_2.pdf&quot;&gt;Here is an interesting paper&lt;/a&gt; on what happens to water droplets when they suddenly encounter a high-speed airstream. It might suggest that such an impact with an aircraft would also cause vaporization, aside from the heat of the surface causing it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even subsonic aircraft windshields are extremely strong; they can take continuous hits from solid hail chunks and not shatter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BzEhm.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BzEhm.jpg&quot; alt=&quot;Heavy hail damage to airliner windshields&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sub&gt;(&lt;a href=&quot;http://kdvr.com/2015/08/08/delta-plane-makes-emergency-landing-in-denver-after-windshield-is-shattered-by-hail/&quot;&gt;source&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-17T02:17:12.593" LastActivityDate="2015-10-17T02:17:12.593" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22089" PostTypeId="2" ParentId="22085" CreationDate="2015-10-16T14:51:42.977" Score="26" Body="&lt;p&gt;The first trick to make windshields stronger is used also in aerodynamics: Sweep reduces the effects of speed. Giving the windshield an inclination both back- and sideways will reduce the impact energy of whatever hits it in flight direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n4SU1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n4SU1.jpg&quot; alt=&quot;X-15 supported on B-52&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-15 carried by a B-52 (picture &lt;a href=&quot;http://www.aviationexplorer.com/x-15_jet_facts.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the angled windows: They were oriented at 75° to the air stream, so an object hitting them at 2,000 m/s (Mach 6.65 at altitude) would &quot;feel&quot; like an impact at 500 m/s against a surface at right angle. Not that it would rain at 80 km up, so this was mostly for aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the second trick is used always if things are at the risk of breaking: Make them thicker! The thickness of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21802/what-kind-of-materials-is-being-used-for-fighter-jets-glass-shields/21806?s=1%7C0.4091#21806&quot;&gt;supersonic fighter canopy&lt;/a&gt; is approximately 20 mm and that of an airliner even 50 mm, whereas your average car glass is only 4 to 6 mm thick. Also, windshields are multi-layered: In airliners as in cars, they are made from tempered glass and polyvinyl butyrate, and the spherical canopies of fighter jets made from polycarbonate, polyurethane and acrylic. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the goal of the engineers is only to make the structure withstand the impacts over a certain time, which can be only minutes for supersonic flight. Birdstrikes are one-time events, but rain impact is an ongoing process which erodes any surface over time. The single raindrop or hail impact will only cause local, microscopic damage, but enough of them over time will wear down any structure.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-10-18T07:50:08.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22090" PostTypeId="2" ParentId="22087" CreationDate="2015-10-16T14:53:03.803" Score="12" Body="&lt;p&gt;Of course, just put the center of gravity back to its rear limit and fly slowly. Then all of them will produce positive lift on their tails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stability is &lt;strong&gt;not&lt;/strong&gt; produced by a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21499/what-causes-tail-down-force&quot;&gt;downforce at the tail&lt;/a&gt;. The newest book I read which claimed this was from 1911 (I happened to read the 1913 edition). Stability is produced by making the lift per area of the forward parts higher than that of the rear parts. If the lift on the forward wing is high enough, the rear wing can provide stability with a positive lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Canards should be the easiest to prove this: Their main wing produces positive lift, and still they can be made to fly stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking for a design which seems to deviate from this basic principle, maybe the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fauvel_AV.36&quot; rel=&quot;noreferrer&quot;&gt;Fauvel AV.36&lt;/a&gt; will do:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3lyl1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3lyl1.jpg&quot; alt=&quot;Fauvel AV.36&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fauvel AV.36 in flight (picture by &lt;a href=&quot;http://orig14.deviantart.net/8186/f/2014/209/7/8/fauvel_av36_by_namelessfaithlessgod-d7sm550.jpg&quot; rel=&quot;noreferrer&quot;&gt;Daniel-Wales-Images&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Charles_Fauvel&quot; rel=&quot;noreferrer&quot;&gt;Charles Fauvel&lt;/a&gt; designed several flying wing gliders, of which the AV.36 is the most popular. All of them had positive, natural pitch stability. There is only one wing, and it &lt;strong&gt;must&lt;/strong&gt; produce lift, or the plane couldn't fly, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only way to really do away with this principle is to give up natural longitudinal stability. Weight and balance would be affected such that the center of gravity is behind the neutral point, where the angle-of-attack-dependent lift force acts. This kind of airplane, however, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8049/are-fighter-jets-designed-to-be-so-inherently-unstable-that-a-human-cant-fly-on/8061#8061&quot;&gt;would be very hard to fly manually&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-10-16T19:43:07.200" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22091" PostTypeId="2" ParentId="22087" CreationDate="2015-10-16T14:57:01.643" Score="16" Body="&lt;p&gt;There are multiple configurations which are possible with tail or canard, which based on their locations and whether they produce lift or down-force, results in a stable or unstable aircraft (taking the aircraft center of gravity into account). The figures below show some of the possible configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Oy28z.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Oy28z.jpg&quot; alt=&quot;Stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: f-16.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the most general case, there is no need for even a canard or a horizontal tail as long as a (down or up) force is produced in some way. A good example is the Boeing Bird of Prey, where the chines produced (vortex) lift and thus a stabilizing force. The forces acting on the longitudinal axis of the aircraft look something like this, leading to a statically stable aircraft without any lifting surface except the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zDcrU.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zDcrU.jpg&quot; alt=&quot;Boeing Bird of Prey&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Profile from bj-o23.deviantart.com, others own work.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-16T15:03:37.317" LastActivityDate="2015-10-16T15:03:37.317" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22092" PostTypeId="2" ParentId="22078" CreationDate="2015-10-16T15:00:25.360" Score="16" Body="&lt;p&gt;The existing answers are, of course, correct that most current UAVs do not have much in the way of options for defending themselves against attacks by fighters. This, however, is due primarily to the design missions of most current UAVs, which are reconnaissance and attacking lightly-defended ground targets. Their mission is literally to be an expendable recon or attack aircraft, therefore it doesn't make a lot of sense to invest millions upon millions of dollars in giving them defensive capabilities. Even most normal manned recon aircraft will be short work for a modern jet fighter, with the typical use case being using actual fighters to keep enemies away from them. With a UAV, there's much less incentive to invest heavily in defending it, since they're generally much cheaper aircraft and losing them doesn't mean losing personnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said all of this, there's nothing inherent about being unmanned that makes an aircraft unable to defend itself. It's just a matter of most current UAVs being designed for use cases where they don't care all that much about defending it, so it's not worth equipping them with lots of excess available lift and thrust, extra sensors, weapons, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's nothing to say you can't design an unmanned fighter aircraft. For example, if the drone you're trying to shoot down happens to be a &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon_variants#QF-16&quot; rel=&quot;noreferrer&quot;&gt;QF-16&lt;/a&gt;, then you're probably going to have a &lt;a href=&quot;http://www.boeing.com/features/2014/08/bds-qf16-08-26-14.page&quot; rel=&quot;noreferrer&quot;&gt;significantly more challenging mission ahead of you&lt;/a&gt;. The QF-16 is exactly what it sounds like - an F-16 that has been modified to act as a UAV. As such, it has the full range of evasive options available to it that you would expect from a normal 4th generation fighter aircraft, since it is one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The U.S. armed forces use the 'Q' designator to mean that an aircraft is a UAV. This is a 'vehicle type' designator in the &lt;a href=&quot;https://en.wikipedia.org/wiki/1962_United_States_Tri-Service_aircraft_designation_system#Vehicle_type&quot; rel=&quot;noreferrer&quot;&gt;1962 United States Tri-Service aircraft designation system&lt;/a&gt;. It is added to the F-16 designation for the unmanned F-16s, but it's also used for all military UAVs, such as the MQ-1 Predator, the MQ-9 Reaper, or the RQ-4 Global Hawk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;QF-16 flying without a pilot:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dJVMW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dJVMW.jpg&quot; alt=&quot;QF-16 flying sans pilot&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-10-16T19:23:15.103" LastActivityDate="2015-10-16T19:23:15.103" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22093" PostTypeId="2" ParentId="22074" CreationDate="2015-10-16T15:09:21.810" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://news.google.com/newspapers?id=U4MTAAAAIBAJ&amp;amp;sjid=TwAEAAAAIBAJ&amp;amp;pg=6024%2C426187&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; from 1952 states an annual production of 5,500 to 6,200 aircraft. Even if this represented the peak production, that seems a bit high compared to the total production number of over 18,000. Some details of how these sorts of estimates were made is available in &lt;a href=&quot;http://www.foia.cia.gov/sites/default/files/document_conversions/89801/DOC_0000381319.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-10-16T15:09:21.810" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22094" PostTypeId="1" CreationDate="2015-10-16T15:14:35.930" Score="0" ViewCount="482" Body="&lt;p&gt;After viewing the movie &quot; Flight&quot;, I was wondering if extended inverted flight was possible with any of the current larger commercial jet aircraft? &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="22726" LastEditDate="2018-10-16T03:00:21.007" LastActivityDate="2018-10-16T03:00:21.007" Title="Is sustained inverted flight possible with any of today's commercial jet aircraft?" Tags="&lt;aircraft-design&gt;&lt;inverted-flight&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ClosedDate="2015-10-16T15:40:42.533" ContentLicense="CC BY-SA 3.0" />
  <row Id="22095" PostTypeId="1" CreationDate="2015-10-16T15:15:02.480" Score="0" ViewCount="228" Body="&lt;p&gt;I understand from &lt;a href=&quot;https://aviation.stackexchange.com/questions/11555/instrument-landing-why-do-all-electronic-devices-need-to-be-shut-off&quot;&gt;discussions such as these&lt;/a&gt;, that it is crucial that to avoid electronic interference with flight instruments, all electronic devices should be shut off during takeoff and landing. And yet, in my experience, there are always rebels getting away with brazenly keeping their instruments on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, given the critical nature of possible interference (tiny probability but catastrophic consequences), why aren't airlines looking at more stringent measures than a routine announcement/request by the pilot? For example manual checks, frisking? &lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-16T15:47:49.880" Title="Why aren't there more stringent checks for switching off electronic devices during takeoff-landing?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-16T15:44:04.533" ContentLicense="CC BY-SA 3.0" />
  <row Id="22096" PostTypeId="2" ParentId="22094" CreationDate="2015-10-16T15:30:37.773" Score="1" Body="&lt;p&gt;&lt;em&gt;Theoretically&lt;/em&gt;, it is possible to fly an aircraft upside down. Good examples are the barrel roll done by Alvin &quot;Tex&quot; Johnson in Dash-80 (the predecessor of Boeing 707) and the actions of Pilot Flying James Tucker during the &lt;a href=&quot;https://en.wikipedia.org/wiki/Federal_Express_Flight_705#Hijacking&quot; rel=&quot;nofollow&quot;&gt;hijacking of Federal Express 705&lt;/a&gt;. However, the question is whether the maneuver can be sustained for and reasonable periods of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this matter, the &lt;a href=&quot;http://edition.cnn.com/2013/01/10/travel/flight-movie-united-232/&quot; rel=&quot;nofollow&quot;&gt;statement of Boeing&lt;/a&gt; (manufacturer of MD-80 after merger with McDonnell Douglas) is instructive:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The MD-80 cannot sustain inverted flight,...The MD-80, as with all commercial airliners, was designed to fly upright. Commercial airliners are only tested and certified for upright flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The pilots of &lt;a href=&quot;https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261&quot; rel=&quot;nofollow&quot;&gt;Alaska Airlines Flight 261&lt;/a&gt;, a MD-83, tried to fly their aircraft upside down for recovery, but were unsuccessful.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-16T15:30:37.773" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22097" PostTypeId="2" ParentId="22095" CreationDate="2015-10-16T15:47:49.880" Score="1" Body="&lt;p&gt;There are some problems with this as electronic equipment are not banned in aircraft per se, but only during some (critical) phases of flight.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;First, how to determine if someone is operating electronic instruments. It'll be difficult, considering that everyone is seated. The only way is to put a lot of cameras (who's going to monitor them?) or by asking everyone to check their fellow passengers, hardly a good option.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even if someone operating an electronic equipment is detected, what to do? During takeoff and landing, seat belts are mandatory and the only option (except announcing the seat number over PA) is to ask the person in nearby seat to snatch the offending equipment; again not a good solution. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As most of the electronic equipment (like camera or music players) emit little radiation and no air crash has been attributed to use of electronic devices, I doubt airlines will do something to physically to prevent passengers from using electronics.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-16T15:47:49.880" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22098" PostTypeId="2" ParentId="9931" CreationDate="2015-10-16T16:12:01.443" Score="5" Body="&lt;p&gt;As for the TAM flight, that does not sound like a High Altitude weather balloon.  That sounded like an unmanned hot air balloon carrying a big banner.  I am guessing, based on the article that it was designed to stay at a lower altitude so people could see the banner.  High altitude weather balloons are like giant party balloons, very thin latex usually.  They generally rise at 1000 ft/min and are out of busy airspace quite quickly.  The payloads are limited to 12 lbs, but usually much lighter.  Mine was just over 2 lbs. If the regulations are followed there is very little risk.   &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/u_Xj0FVdVrE?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; Good luck, do your research, and have fun.    &lt;/p&gt;&#xA;" OwnerUserId="11823" LastActivityDate="2015-10-16T16:12:01.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22099" PostTypeId="2" ParentId="22085" CreationDate="2015-10-16T16:18:57.637" Score="10" Body="&lt;p&gt;&lt;em&gt;How do aircraft windshields not crack when flying through precipitation at supersonic speeds?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are talking about a phenomenon called rain erosion at supersonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See: &lt;a href=&quot;http://oai.dtic.mil/oai/oai?verb=getRecord&amp;amp;metadataPrefix=html&amp;amp;identifier=AD0482638&quot;&gt;INVESTIGATION OF THE PHENOMENA OF RAIN EROSION AT SUBSONIC AND SUPERSONIC SPEEDS&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just because a small steel ball of mass m, traveling at supersonic speeds, can crack a windshield, it does not mean a water droplet of the same mass and velocity will produce the same effect even if it has the same energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple explanation can be given based on elastic and inelastic collisions theory, you know from school. The steel ball hitting the glass is in the elastic collision case characterized by high interaction forces, at least up to the moment the glass breaks. The water drop is in the inelastic situation, the impact forces being lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are in the case of a soft ball and a stone of the same mass hitting a window with the same speed. In the first case the glass survives in the second breaks.  &lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-16T16:18:57.637" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22101" PostTypeId="2" ParentId="14782" CreationDate="2015-10-16T16:43:51.950" Score="0" Body="&lt;p&gt;There is a rule in the FAA part 101 regulations that has been interpreted to mean that you cannot launch anything from a high altitude balloon... &#xA;   &quot;(b) No person operating any moored balloon, kite, unmanned rocket,&#xA;   or unmanned free balloon may allow an object to be dropped&#xA;   therefrom, if such action creates a hazard to other persons or&#xA;   their property.&quot;&lt;br&gt;&#xA;That seems to be for security, keeping people with bad intentions from launching bombs on rockets, etc. Same with most GPS devices being limited to 20,000 ft. However, it you obtain permission to do it, please post a video!  Good luck.&lt;/p&gt;&#xA;" OwnerUserId="11823" LastActivityDate="2015-10-16T16:43:51.950" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22102" PostTypeId="2" ParentId="22083" CreationDate="2015-10-16T16:47:59.340" Score="12" Body="&lt;p&gt;The Concorde was first used for observing solar eclipse in 1973. The aircraft used was Concorde 001, piloted by André Turcat with a scientific team of 8 people from US, UK and France. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason for using Concorde was that the eclipse can be observed above the clouds for far longer than on ground by literally 'chasing the moon'. Multiple instruments were used for observing the eclipse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Institut Astrophysique de Paris used cameras to capture images of the eclipse using a telescope mounted on anti-vibration mounts, which looked out of the aircraft through one of five silica quartz windows installed in the Concorde's roof. The equipment is shown in the image below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FBg3s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FBg3s.jpg&quot; alt=&quot;Telescope&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: xjubier.free.fr&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Queen Mary College's InSb Far-Infrared Detector experiment consisted of an interferometer that used a tracking mirror to view the solar eclipse via a quartz window fitted into the roof of the cabin, as shown in this image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tn50D.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tn50D.jpg&quot; alt=&quot;Far Infrared Detector&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: jcgl.orpheusweb.co.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dark opening in the roof holds the quartz window of the cabin, which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SSwos.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SSwos.jpg&quot; alt=&quot;Roof Opening&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: xjubier.free.fr&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was the most important (structural) modification made in the Concorde (BAC was supposed to provide Concorde 002 for this flight, but they backed out when they realized that some holes were to be made in the roof).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Los Alamos Scientific Laboratory (LASL, later to become Los Alamos National&#xA;Laboratory) used a specially-designed 3-inch telescope which looked out of the&#xA;aircraft through a silica quartz windows installed in the Concorde's roof. One objective of the research was to look for oscillations in the sun's corona that occurred on a time scale of about five minutes (the eclipse was visible for ~74 minutes from Concorde).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instruments were checked both in ground and air before the experiment.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Before installation of the instruments on the aircraft, they were tested on a low speed trolley, perhaps to check its sensitivity to movement.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;After the ground test, they were installed on the aircraft and connected to the aircraft power system and checked.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Before the actual experiment, the aircraft were flight tested at supersonic speed with the instruments on board.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The Concorde was chartered for viewing Halley's Comet in 1986 and for viewing solar eclipse in 1999. These were chartered sightseeing flights (using unmodified aircraft), not scientific ones.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-16T16:47:59.340" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22103" PostTypeId="2" ParentId="22085" CreationDate="2015-10-16T17:36:24.573" Score="6" Body="&lt;p&gt;Because aircraft don't regularly fly at such speeds at altitudes where this might be a concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quoted problem (hitting a drop of water faster then the speed of sound in water) is &lt;strong&gt;never faced by any real aircraft&lt;/strong&gt;. Even if because of the shock-wave there was no windshield in existence that would survive that impact, it wouldn't pose a problem, because no aircraft flies at Mach 4 at an altitude where it can encounter rain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, no aircraft was ever capable of cruising at Mach 4. Besides some experimental prototypes, no aircraft could even fly at Mach 4.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even the handful of aircraft which can reach about Mach 3, can only do it high in the stratosphere, where the air is much thinner and there is no rain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, hitting a raindrop at Mach 4 is not an issue, because no aircraft can fly that fast. Actually, no aircraft flies much faster than Mach 1 at altitudes where rain is possible. &#xA;Even the planned future aircraft which will be capable of sustained flight over Mach 4, will fly at that speed only when high above the clouds, because they would not be able to fly that fast where the air is thicker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the problems would arise at Mach 1, aircraft regularly fly supersonic only in the stratosphere, where there is no rain. Actually, very few aircraft fly supersonic: airliners (except for the Concorde) are all subsonic, and even the Concorde only flew supersonic when it was flying high enough. Military aircraft, although many of them capable of supersonic flight, &lt;a href=&quot;https://aviation.stackexchange.com/a/21988/1307&quot;&gt;rarely ever fly supersonic&lt;/a&gt;, and even then only for short bursts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, summarized:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;supersonic aircraft fly usually not much above the speed of sound and so they can easily slow down to subsonic speeds when encountering rain. (maybe someone can help out whether there was anything in the Concorde flight manual about the maximum allowed speed in rain)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;aircraft rarely (if ever) fly supersonic at altitudes where rain is a concern. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1307" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-16T20:55:49.950" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22105" PostTypeId="2" ParentId="22087" CreationDate="2015-10-16T20:02:57.160" Score="10" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Tandem_wing&quot;&gt;tandem wing&lt;/a&gt; airplane has two sets of wings, each providing upward lift. One is near the front of the plane, one is near the back, and the center of gravity is between them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qnPYA.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qnPYA.jpg&quot; alt=&quot;tandem wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(source: &lt;a href=&quot;http://www.nurflugel.com/Nurflugel/n_o_d/oldstuff/html/weird/tandem.htm&quot;&gt;nurflugel.com&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Rutan_Quickie&quot;&gt;Rutan Quickie&lt;/a&gt; is one such plane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M0I6T.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M0I6T.jpg&quot; alt=&quot;Rutan Quickie&quot;&gt;&lt;/a&gt;&#xA;(souce: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/d/de/Rutan_quickie_q2.jpg&quot;&gt;wikimedia&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This design is actually fairly old; it even predates (successful) heavier-than-air flight, as it was used on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Langley_Aerodrome&quot;&gt;Langley Aerodrome&lt;/a&gt;, an experimental attempt at manned flight in the 1890s.&lt;/p&gt;&#xA;" OwnerUserId="7793" LastEditorUserId="7793" LastEditDate="2015-10-16T20:52:10.210" LastActivityDate="2015-10-16T20:52:10.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22106" PostTypeId="1" AcceptedAnswerId="22110" CreationDate="2015-10-16T20:28:53.403" Score="6" ViewCount="1991" Body="&lt;p&gt;Rocket engines typically employ a cooling jacket of sorts, usually dual-purposing the fuel as a liquid coolant before it flows into the injectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example turbojet using a bypass. As you can see, the bypass air is far cooler in temperature than the air combustion chamber:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PlqNh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PlqNh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://en.citizendium.org/images/thumb/8/85/Turbofan.png/450px-Turbofan.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are there no designs that use an air bypass (similar to a turbojet) to cool the engine/nozzle? Obviously once the rocket has escaped the atmosphere, a bypass would be of little use. However usually by that stage in a rocket, thrust has been greatly reduced and therefore generated heat as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't a bypass cooling system make a rocket engine a tad less complex (especially for the first stage)?&lt;/p&gt;&#xA;" OwnerUserId="2294" LastEditorUserId="5517" LastEditDate="2017-04-14T11:53:05.680" LastActivityDate="2018-07-25T23:49:14.883" Title="Could bypass air be used to cool a rocket engine like in turbofans?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;engine&gt;" AnswerCount="4" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22107" PostTypeId="2" ParentId="22106" CreationDate="2015-10-16T20:38:53.523" Score="6" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Air-augmented_rocket&quot;&gt;air augmented rocket&lt;/a&gt; uses air from the freestream to provide extra thrust (and potentially) cool the motor. Two of the main issues with trying to add 'extra' air into the rocket stream are: drag over the rocket body (pretty much the main one) and disruption of the high-temperature flow (especially if you are trying to introduce air somewhere around the nozzle). &lt;/p&gt;&#xA;" OwnerUserId="11231" LastActivityDate="2015-10-16T20:38:53.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22109" PostTypeId="2" ParentId="22057" CreationDate="2015-10-16T20:56:06.327" Score="2" Body="&lt;p&gt;In case you're interested, US Patent 7,752,834 has what I was looking for. &lt;img src=&quot;https://patentimages.storage.googleapis.com/US7752834B2/US07752834-20100713-D00000.png&quot; alt=&quot;US-7752834&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="11799" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.530" LastActivityDate="2015-10-16T20:56:06.327" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22110" PostTypeId="2" ParentId="22106" CreationDate="2015-10-16T22:15:44.140" Score="11" Body="&lt;p&gt;Air cooling is not going to contribute much here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Shuttle engines were cooled by liquid hydrogen (-253°C) from the fuel supply being pumped up cooling ducts inside the nozzle. Typical nozzle temperature in operation was around 54°C. Yes, fifty-four Celsius. (BBC Engineering Connections - see &lt;a href=&quot;https://www.youtube.com/watch?v=FH_iiX8nA5M&quot;&gt;this Youtube clip&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The top speed of the SR-71 (about Mach 3.2) was limited by the temperature of the air arriving at the engines which, after being compressed in the inlet ducts, reached temperatures around 400°C. (&lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird#Engines&quot;&gt;Wikipedia: SR-71&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shuttle passes Mach 4 about 2 minutes after launch.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastEditorDisplayName="user11516" LastEditDate="2015-10-16T22:56:46.463" LastActivityDate="2015-10-16T22:56:46.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22111" PostTypeId="2" ParentId="21665" CreationDate="2015-10-16T22:16:18.150" Score="31" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aeronautical data (fixes, waypoints, navaids, instrument procedures) are delivered to aircraft operators and avionics manufacturers referenced to the WGS-84 ellipsoid. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make is simple the ellipsoid is the volume enclosed by the revolution of an ellipse which best approximates the shape of the Earth, generally &lt;em&gt;in a given region&lt;/em&gt; only. WGS ellipsoid is a global one which approximates the whole Earth shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Rf4RN.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rf4RN.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA provides rules for designing procedures, and algorithms to use to compute various elements, including the distance between two fixes and their relative azimuths. This is described in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.54A.pdf&quot; rel=&quot;noreferrer&quot;&gt;Order 8260.54&lt;/a&gt; The United States Standard for Area Navigation (RNAV), Appendix 2. TERPS Standard Formulas for Geodetic Calculations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.0 Purpose&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The ellipsoidal formulas contained in this document must be used in&#xA;  determining  RNAV flight path (GPS, RNP, WAAS, LAAS) fixes,&#xA;  courses, and distance between fixes. Notes: Algorithms and methods&#xA;  are described for calculating geodetic locations (latitudes and &#xA;  longitudes) on the World Geodetic System of 1984 (WGS-84)&#xA;  ellipsoid, resulting from intersections of geodesic and non-geodesic &#xA;  paths. These algorithms utilize existing  distance and azimuth&#xA;  calculation methods to compute intersections and tangent points &#xA;  needed for area navigation procedure construction. The methods apply&#xA;  corrections to  an initial spherical approximation until the error is&#xA;  less than the maximum allowable error, as specified by the user.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3.4 Direct and Inverse Algorithms.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Direct and Inverse cases utilize formulae from T. Vincenty’s,&#xA;  Survey Review XXIII, No. 176, April 1975: Direct and Inverse Solutions&#xA;  of Geodesics on the Ellipsoid with Application of Nested Equations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FMS use &lt;a href=&quot;https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid&quot; rel=&quot;noreferrer&quot;&gt;ellipsoid geometry&lt;/a&gt; to compute distances and angles, in order to match aeronautical data. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A visible consequence is that, except for meridians and equator, prlongating a geodesic on an ellipsoid doesn't draw a closed curve, as if it were a great circle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RQkp9.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RQkp9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Detailed answer: Need for WGS-84&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;New modes of navigation have emerged with a significantly better accuracy than using VOR-DME and inertial:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;RNAV (area navigation) generally uses GNSS (global navigation satellite system, one GNSS being the US GPS),&lt;/li&gt;&#xA;&lt;li&gt;RNP (required navigation performance),&lt;/li&gt;&#xA;&lt;li&gt;and more generally performance-based navigation (PBN).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At the same time these new direct modes of navigation (compared to a navaid-to-navaid paths) can define paths extending to thousands of NM, and commonly crossing different geodetic reference systems where latitude, longitude, height and vertical can have significantly different values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an illustration, the measure of &quot;height&quot; used to be referenced to local MSL (mean sea level):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h5Ms6.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h5Ms6.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://cct.gfy.ku.dk/publ_cct/cct1721.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But a GPS receiver, which is now the main instrument to locate a point, can only provide the height above an ellipsoidal simplified Earth model. Latest receivers also provide the height above the simplified sea level model (&lt;a href=&quot;https://en.wikipedia.org/wiki/Geoid&quot; rel=&quot;noreferrer&quot;&gt;geoid&lt;/a&gt;), but only as the result of a transformation of the ellipsoidal height, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gRbTt.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gRbTt.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.beg.utexas.edu/coastal/poster/vertdataadjustmnt.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As visible above, the direction of the local vertical is impacted by the transformation, creating another problem for airborne vehicles navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can &lt;a href=&quot;http://kartoweb.itc.nl/geometrics/reference%20surfaces/body.htm&quot; rel=&quot;noreferrer&quot;&gt;quickly become a nightmare&lt;/a&gt; with differences for the same point up to 100m depending on the reference used:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For these reasons, it appeared very early that all elements involved in mapping, navigation and ATC must use the same datum, in all countries. ICAO has selected WGS-84.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/NACC/Documents/Meetings/2014/ECARAIM/REF08-Doc9674.pdf&quot; rel=&quot;noreferrer&quot;&gt;ICAO Doc9674&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Council [...] on 28 February 1994, adopted Amendment 28 to Annex 15,&#xA;  introducing the provisions concerning the promulgation of WGS-84-related&#xA;  geographical coordinates. [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;WGS-84 on &lt;a href=&quot;https://en.wikipedia.org/wiki/World_Geodetic_System&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The WGS 84 datum surface is an oblate spheroid (ellipsoid) with major&#xA;  (equatorial) radius a = 6378137 m at the equator and flattening f =&#xA;  1/298.257223563. The polar semi-minor axis b then equals a times&#xA;  (1−f), or 6356752.3142 m.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Current country compliance with ICAO selected datum: See &lt;a href=&quot;http://ww1.jeppesen.com/company/publications/wgs-84.jsp&quot; rel=&quot;noreferrer&quot;&gt;Jeppesen WGS-84 Status Report&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aeronautical databases&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FMS uses aeronautical data (fixes, procedures) in the &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC_424&quot; rel=&quot;noreferrer&quot;&gt;ARINC 424&lt;/a&gt; format, where legs are WGS-84 paths.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SvuhS.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SvuhS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Processing of aeronautical data&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've had difficulty to get the exact authoritative document making mandatory the use of ellipsoid geometry in a FMS, however, from FAA &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/nd/8260_52.pdf&quot; rel=&quot;noreferrer&quot;&gt;Order 8260.52&lt;/a&gt; related to RNP, FMS are part of the so called GPN means which are referenced to WGS-84:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Geographic Positioning Navigation (GPN).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Navigation based on geodetic&#xA;  calculation of geographic position referenced to the WGS-84 ellipsoid.&#xA;  Global positioning system (GPS), wide area augentation system  (WAAS),&#xA;  local area augmentation system (LAAS), flight management system (FMS),&#xA;  RNP, and area navigation (RNAV) are examples of GPN.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When calculating distances between fixes, or angles, a FMS computes geodesics which are shortest paths between fixes. On a sphere this would be a great circle. On an ellipsoid this has &lt;a href=&quot;https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid&quot; rel=&quot;noreferrer&quot;&gt;to be adjusted&lt;/a&gt;, Vincenty's formulas are one of the methods that can be used for approximation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additional details on how geodesic calculations are done can be found in FAA &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FAA_Order_8260.58.pdf&quot; rel=&quot;noreferrer&quot;&gt;Order 8260.58&lt;/a&gt; related to Performance Based Navigation.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-11-09T07:49:47.183" LastActivityDate="2017-11-09T07:49:47.183" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22112" PostTypeId="1" AcceptedAnswerId="22113" CreationDate="2015-10-16T23:42:38.353" Score="8" ViewCount="1394" Body="&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/j_D8tcnL2uQ?start=1526&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This video says (&lt;a href=&quot;https://www.youtube.com/watch?v=j_D8tcnL2uQ&amp;amp;t=25m06s&quot; rel=&quot;nofollow noreferrer&quot;&gt;at 25:06&lt;/a&gt;) that you should do it as soon as possible.&#xA;but I just learned in class that you should wait for an ice build up then turn it on vs just turning it on. This would prevent an ice bridge to form: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gkUTJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gkUTJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in the clip it says modern de-ice boots don't have the problem mentioned in the picture. &lt;/p&gt;&#xA;" OwnerUserId="11761" LastEditorUserId="19" LastEditDate="2015-10-17T10:20:55.213" LastActivityDate="2015-10-17T10:20:55.213" Title="When to turn on deice boots?" Tags="&lt;aircraft-design&gt;&lt;anti-ice&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22113" PostTypeId="2" ParentId="22112" CreationDate="2015-10-17T02:00:16.457" Score="10" Body="&lt;p&gt;There was a belief that activating de-icing boots too early could result in an ice bridge forming over the boot and rendering it ineffective. This led to a recommendation that de-icing boots should not be activated until a significant build-up of ice had occurred.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F1xZV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F1xZV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: FAA)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recent testing has established that modern de-icing boots are not susceptible to this problem, and advice from the FAA has been changed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2009/inFO09007.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;InFO9007&lt;/a&gt; (dated 5th May 2009) the specific advice given is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots should follow the boot activation and operating procedures&#xA;  specified in the AFM or FAA approved operator’s manual for the&#xA;  airplane they are flying&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And further:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the AFM does not have specific boot operation procedures or if ice&#xA;  thickness is difficult to judge, pilots should not be reluctant to&#xA;  cycle modern boots at the first sign of ice accretion and then as&#xA;  needed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A 'modern boot' is defined in the same publication as having &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;less than 1.75 inch diameter tubes, operating pressures of 15 psig or&#xA;  greater, and fast inflation/deflation times&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also suggest that any aircraft built later than 1960 is likely to have modern boots.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Essentially, for most cases that you might encounter the video clip is correct, and your class instructor is wrong. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, the definitive guide should always be the Pilot's Operating Handbook for the aircraft you are flying.&lt;/p&gt;&#xA;" OwnerDisplayName="user11516" LastActivityDate="2015-10-17T02:00:16.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22114" PostTypeId="1" AcceptedAnswerId="22124" CreationDate="2015-10-17T09:24:52.997" Score="4" ViewCount="1829" Body="&lt;p&gt;Given how rare airplane component failures have become today, I'm curious, are there still any components which are commonplace on aircraft, but still see a high failure rate? If so, why are these components used? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not, are there any specific regulations to prevent this kind of thing?&lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-10-19T07:58:22.577" Title="What component of an aircraft is most likely to fail?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22115" PostTypeId="1" CreationDate="2015-10-17T11:25:48.347" Score="1" ViewCount="37" Body="&lt;p&gt;Just like in buses on road, we feel more shaky when we sit in the back seats than the driver and other sitting in front. Is it the same for flights when we are in clouds?&lt;/p&gt;&#xA;" OwnerUserId="11840" LastEditorUserId="1467" LastEditDate="2015-10-17T11:50:30.303" LastActivityDate="2015-10-17T11:50:30.303" Title="Do we shake more if we are seated towards the tail rather than in the middle or the front?" Tags="&lt;passenger&gt;&lt;turbulence&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-10-17T13:20:05.137" ContentLicense="CC BY-SA 3.0" />
  <row Id="22116" PostTypeId="1" CreationDate="2015-10-17T12:04:01.553" Score="5" ViewCount="575" Body="&lt;p&gt;Four months ago I travelled to US (my 3rd time visit) from India. I always have that aerophobia just before and during flying but it has grown exponentially when the American Airlines flight took-off from UK (connecting flight) that shook a lot on runway and making lot of noise from inside (probably the cabinet doors). This made me very scare because I never had such experience and after it tookoff into the air it was shaking a lot and moving slightly up and down, may be because of heavy wind. I was so scared and thinking there could be something wrong. My BP raised when I saw lady sitting next to me. While I was trying to stay calm and act like normal, looking at her facial expressions it gave me strong feeling that something is wrong and I was watching outside from the window and then flight took a sudden turn to the left which I felt like the plan going to crash and again that body language of women sitting next to me multiplied my anxiety.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It took me nearly one hour for me to settle down. I drunk 4 pegs of whisky and went to semi-sleep for around 6 hours. Every time plane shook I said to my self &quot;If flight crashes, I am not going to get injuries or handicapped, I will only die&quot;. I could not forget this experience even after I reached home in US, for nearly 1 month I use to get nervous about thinking of flying back. I even avoided Dallas-Vegas-Dallas trip by flight by convincing my friends that it would be fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I managed to settle my self only after I half-travelled back to India and said &quot;Nothings gonna happen, thousands of flights fly everyday&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any techniques people adopt for controlling this fear? While travelling back I noticed a crew member closed her eyes at the time of takeoff and landing. Does it help anyway? Was that bad experience for sitting on the last second row?&lt;/p&gt;&#xA;" OwnerUserId="11840" LastEditorUserId="62" LastEditDate="2015-10-17T14:38:19.330" LastActivityDate="2015-10-17T14:38:19.330" Title="How to control fear of flying?" Tags="&lt;safety&gt;&lt;passenger&gt;&lt;medical&gt;&lt;turbulence&gt;" AnswerCount="0" CommentCount="12" ClosedDate="2015-10-17T15:15:58.077" ContentLicense="CC BY-SA 3.0" />
  <row Id="22118" PostTypeId="2" ParentId="12930" CreationDate="2015-10-17T16:01:18.943" Score="0" Body="&lt;p&gt;It is the Shorts SC-7. You can see the short nose compared to the C-23 Sherpa. I too thought C-23 because I worked on them in the US Air Force.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3YNjW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3YNjW.jpg&quot; alt=&quot;Kingsman_SC-7_vs_C-23&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11847" LastActivityDate="2015-10-17T16:01:18.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22120" PostTypeId="1" AcceptedAnswerId="22122" CreationDate="2015-10-17T20:01:07.067" Score="14" ViewCount="16893" Body="&lt;p&gt;I want to know the difference between CAN and ARINC, I'm confused about their usage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the communication between the cockpit and the controllers is done using ARINC protocols. And the data transmitted by probes to the controllers goes over CAN. Why use a different protocol in each case? When is each protocol used?&lt;/p&gt;&#xA;" OwnerUserId="11850" LastEditorUserId="19" LastEditDate="2016-10-17T07:59:44.467" LastActivityDate="2019-03-18T20:26:09.367" Title="What is the difference between CAN and ARINC?" Tags="&lt;avionics&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22122" PostTypeId="2" ParentId="22120" CreationDate="2015-10-17T20:52:41.157" Score="17" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;the communication between the cockpit and the controllers is done by using Arinc protocols. And the data transmitted by probes to the controllers is done by CAN.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That depends very much on the aircraft type. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And when can we use each one of them (Arinc and CAN)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When you design your own aircraft you get to choose.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;CAN stands for &lt;a href=&quot;https://en.wikipedia.org/wiki/CAN_bus&quot;&gt;Controller Area Network&lt;/a&gt;. CAN is a bus standard designed to allow microcontrollers and devices to communicate with each other in applications without a host computer. It has its origins in the automotive industry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ARINC stands for &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC&quot;&gt;Aeronautical Radio&lt;/a&gt;, Incorporated. ARINC is an organisation that amongst other activities produces technical standards for avionics and provides services to aircraft operators. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Amongst the ARINC standards there are a number addressing data communications between avionics components. Most widely used is the &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC_429&quot;&gt;ARINC 429&lt;/a&gt; standard which describes an avionics data bus. ARINC 429 allows a single transmitter to communicate data to up to 20 receivers over a single bus. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparing CAN bus to ARINC 429:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cable&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CAN: STP or UPT, possible to implement on fiberoptic cable&lt;/li&gt;&#xA;&lt;li&gt;ARINC 429: STP&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Speed&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CAN: 1 Mbit/s (high speed) / 125 Kbit/s (low speed)&lt;/li&gt;&#xA;&lt;li&gt;ARINC 429 100Kbit/s (high speed) / 10-14 Kbit/s (low speed)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Directionality&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CAN: bi-directional, connected units can send and receive on the same cable. &lt;/li&gt;&#xA;&lt;li&gt;ARINC 429: uni-directional, a unit either transmits or receives from a cable.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Number of units on a single bus&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CAN: unlimited, although in practice no more than about 32 units will be sharing a bus to avoid data collisions.&lt;/li&gt;&#xA;&lt;li&gt;ARINC 429: one transmitter can serve at most 20 receiving units on a single cable.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since ARINC 429 has only a single transmitter, timely data arrival is guaranteed, while CAN has to incorporate transmission collision detection &amp;amp; correction which incurs non deterministic time overhead. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, ARINC 429 only uses a parity bit for bit level error detection whilst CAN allows for various methods including CRC checks&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of this data is obtained from an article on CAN bus in &lt;a href=&quot;http://www.aviationtoday.com/av/issue/feature/CAN-Bus-in-Aviation_31468.html#.ViKwKZekU_s&quot;&gt;avionics magazine&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newer ARINC busses like 629 or &lt;a href=&quot;https://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet&quot;&gt;664 (AFDX)&lt;/a&gt; allow for higher speeds and bi-directional communication. These may eventually replace ARINC 429 (but never underestimate how slow progress in aviation is)&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-17T21:26:13.547" LastActivityDate="2015-10-17T21:26:13.547" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22123" PostTypeId="2" ParentId="22074" CreationDate="2015-10-17T21:15:36.127" Score="4" Body="&lt;p&gt;My reference is the &lt;a href=&quot;https://ospreypublishing.com/the-osprey-encyclopedia-of-russian-aircraft-1875-1995-hb&quot; rel=&quot;nofollow&quot;&gt;Osprey Encycopledia of Russian Aircraft&lt;/a&gt;, but even here no yearly figures are listed. But it gives a little more details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MiG OKB started work on type S (for strelovidnost = swept) in March of 1946 and based it on German work which had determined that a backward-swept midwing configuration with central intake was the best compromise. The first prototype S-01 flew first on Dec. 30, 1947, followed by S-02 on May 27, 1948. The third prototype S-03 had numerous changes applied (many of them diligently listed in the book) and flew first on June 17, 1948. In August 1948 it was selected for mass production as the MiG-15. Initial production started at &lt;a href=&quot;https://en.wikipedia.org/wiki/GAZ&quot; rel=&quot;nofollow&quot;&gt;GAZ&lt;/a&gt;-1 with the first aircraft delivered to service units on October 8, 1948. The Politburo decided on March 20, 1949, to increase production, so the plants that were building the La-15, Li-2, Yak-17 and -23 were all switched over to the MiG-15. Until 1956 12,000 units were built in 17 versions, more than half of them (6,500) as two-seater trainers (MiG-15UTI), built from the second half of 1950 on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Czech license-built S-102 are given with 853 units, built between 1953 and 1955 and the Polish LIM-1 with 54 units.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MiG-15bis is listed separately and started production from early 1952 on. In Czechoslovakia 620 were license-built as the S-103 and in Poland as LIM-2 (no numbers given).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The book is clearly more for engineers than for production people. Would you know that the MiG-15 ejection seat needed different cartridges in winter than in summer, or that the MiG-15 Burlak was equipped with a harpoon to catch a cable towed behind the wing of a bomber, so it could fly in tow to be available as fighter cover over the target area? Since the engine was shut down for cruise, the pilot froze abjectly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MiG-17 started deliveries from October 1952 on, so it is fair to assume that the bulk of MiG-15 were built between the second half of 1949 and 1952. If you split those three years evenly, the yearly production figure would be 4,000. Now subtract a few hundred for the initial production and some more for the later production years (mostly MiG-15UTI), and I would expect that the highest yearly production was maybe 3,000, with many of the 6,500 MiG-15UTI built between 1953 and 1956.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the production numbers listed in the book I have a hard time to reach anything close to those 18,000 given in Wikipedia. Many of the MiG-15s flown in East Bloc countries were produced in Russia and exported. The number of exported MiG-15UTI is given as over 1,960 alone.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-17T21:15:36.127" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22124" PostTypeId="2" ParentId="22114" CreationDate="2015-10-17T21:19:59.583" Score="13" Body="&lt;p&gt;Aside from the obligatory &lt;a href=&quot;https://aviation.stackexchange.com/questions/8292/&quot;&gt;&quot;The Pilot&quot;&lt;/a&gt; answer, there are some components on an aircraft that will certainly fail at a higher rate than other components.&lt;br&gt;&#xA;From the Piston GA side of the equation I can name a few (some of which are also applicable to turbine aircraft).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Incandescent Light Bulbs&lt;/strong&gt;&lt;br&gt;&#xA;A lightbulb is a supremely unreliable device: A delicate bit of wire is suspended in a thin glass envelope and heated until it glows - then subjected to vibration (from the engines, turbulence, etc.) in flight. We use them &lt;em&gt;all over the airplane&lt;/em&gt; -- Position lights, landing lights, cockpit instrument lighting, etc. If you think about how often incandescent light bulbs burn out in your house it's probably not surprising that they fail quite often on aircraft. &lt;a href=&quot;https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401&quot; rel=&quot;nofollow noreferrer&quot;&gt;One such failure lead to a famous crash&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We still use incandescent lightbulbs because they're cheap: A $0.25 light bulb can be replaced multiple times before its cost even approaches the capital investment in a better solution.&lt;br&gt;&#xA;  Modern aircraft are incorporating an increasing number of LEDs to replace incandescent lightbulbs - these solid-state devices have a lower failure rate (and other benefits).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Batteries&lt;/strong&gt;&lt;br&gt;&#xA;Much like your car aircraft rely on batteries for some functions (like starting the engines or the APU). Batteries have a finite service life and will eventually fail to hold a charge and need to be replaced.&lt;br&gt;&#xA;Sometimes &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems&quot; rel=&quot;nofollow noreferrer&quot;&gt;battery failures can be rather dramatic&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We still use batteries because hand-propping aircraft can be dangerous, and getting the APU turbine up to speed without a battery would be nearly impossible. Also if the engine-driven generators fail the battery is a useful source of electricity to help you get to a safe landing site.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Spark Plugs&lt;/strong&gt;&lt;br&gt;&#xA;Piston engines are spark-ignition, and spark plugs have a variety of failure modes (they can become fouled with lead or carbon deposits, the internal resistor can fail, or the electrodes can simply wear out).&lt;br&gt;&#xA;These failures are not uncommon: Statistically if you fly piston aircraft long enough you'll probably encounter at least one of them.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We use spark plugs for obvious reasons: Unless the fuel is ignited it doesn't generate any power. Without power the propeller doesn't turn (at least not very fast), so there's no thrust. No thrust means no flying.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Tires&lt;/strong&gt;&lt;br&gt;&#xA;Tires are another aircraft component with multiple failure modes. Interesting ones include leaks (air leaving the tire at a rate fast enough to be a problem), &quot;catastrophic&quot; failures where the tire explodes or disintegrates while rolling, and &quot;self-protective&quot; failures (where the tire reaches a temperature that melts the fusible plug and causes it to deflate to prevent it from exploding).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tires are also used for an obvious reason: Aircraft that constantly belly-land require expensive maintenance (to say nothing of the damage they do to the airport), and the alternatives - skis, pontoons, or flying boats - are limited in the areas from which they can operate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Air Filters&lt;/strong&gt;&lt;br&gt;&#xA;On piston engines there is normally an intake air filter which is designed to keep dust and grit out of the engine. These filters can fail by becoming clogged (which I suppose isn't really a failure: The filter is doing its job), and certain paper filters can fail by disintegrating and being ingested into the engine (the FAA has issued &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/2BA8EAB12B8CE12186256A380049C63B?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;airworthiness directives&lt;/a&gt; on this subject).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We still use air filters - even the paper kinds that can disintegrate - because ingesting dirt into a piston engine greatly accelerates wear. The required maintenance on the air filter costs less than increased overhaul frequency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-10-19T07:58:22.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22126" PostTypeId="1" AcceptedAnswerId="22131" CreationDate="2015-10-17T23:43:31.243" Score="8" ViewCount="2135" Body="&lt;p&gt;A retired pilot I know told me about his time flying a Cessna 441 Conquest II. He said that after shut down he'd have to go out and motor the props. What engines require this procedure and what is the purpose?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2017-09-21T09:27:56.543" Title="Why do some turboprop engines require motoring after shut down?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22127" PostTypeId="1" AcceptedAnswerId="22129" CreationDate="2015-10-18T00:20:36.990" Score="4" ViewCount="404" Body="&lt;p&gt;I was listening to Gander Radio on HF at 5616 kHz today and I've noticed that operator at Gander would often start transmitting reply before the airplane finished transmission, as if trying to interrupt radio operator on the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me, this was very unusual behavior. From what I've heard and from what I concluded after listening to frequencies, it seems that HF radios in aeronautical mobile service work in traditional simplex mode, so crew normally crew wouldn't be able to hear the part of transmission send before they stop keying their radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this brings me to these questions: &#xA;Are aviation HF radios capable of receiving while transmitting? If so, how?&lt;br&gt;&#xA;Or if not, what's the point of Gander stepping on the plane's transmission? &lt;/p&gt;&#xA;" OwnerUserId="2998" LastActivityDate="2019-03-05T18:45:51.333" Title="Can aviation HF radios receive while transmitting?" Tags="&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22128" PostTypeId="1" AcceptedAnswerId="22130" CreationDate="2015-10-18T02:11:09.260" Score="8" ViewCount="1850" Body="&lt;p&gt;I noticed that the frequency of this VOR-DME is covered by crosshatching. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/3hw4m.jpg&quot; alt=&quot;detail of sectional&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA chart guide says this &quot;indicates shutdown status.&quot; &#xA;&lt;img src=&quot;https://i.stack.imgur.com/EZfyP.jpg&quot; alt=&quot;chart guide detail&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does this mean? Is this navaid being decommissioned?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-18T03:08:30.663" Title="What does the crosshatching mean on this VOR-DME?" Tags="&lt;navaids&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22129" PostTypeId="2" ParentId="22127" CreationDate="2015-10-18T02:36:13.437" Score="4" Body="&lt;p&gt;In general, the HF radios in aviation work in simplex mode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;em&gt;Annex 10 to the Convention on International Civil Aviation- Aeronautical Telecommunications Volume V Aeronautical Radio Frequency Spectrum Utilization&lt;/em&gt; Chapter 3, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3.1.1 In the aeronautical mobile service, single channel simplex shall be used in radiotelephone communications utilizing radio frequencies below 30 MHz in the bands allocated exclusively to the aeronautical mobile (R) service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though some aviation radios are capable of semi-duplex operation, virtually all aviation services operate on simplex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea why the operator was stepping on the aircraft's transmission though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-18T02:36:13.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22130" PostTypeId="2" ParentId="22128" CreationDate="2015-10-18T02:55:25.373" Score="7" Body="&lt;p&gt;You're right. From &lt;em&gt;FAA Aeronautical Chart User’s Guide&lt;/em&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NAVAIDS in a shutdown status have the frequency and channel number  crosshatched. Use of the NAVAID status “shutdown” is only used when a facility has been decommissioned but cannot be published as such because of pending airspace actions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/imbxJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/imbxJ.png&quot; alt=&quot;Shutdown Status&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;FAA Aeronautical Chart User’s Guide&lt;/em&gt;, 12th Ed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA is in the process of reducing the VOR based navigation network to minimum levels so as to provide only an alternate means of navigation in case of Global Navigation Satellite System (GNSS) outage. This VOR Minimum Operational Network (MON) is expected to be in place by the year 2020, which will permit non-GNSS guidance to an airport within 100 nautical miles (nm) that has an ILS or VOR approach procedure.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-18T03:08:30.663" LastActivityDate="2015-10-18T03:08:30.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22131" PostTypeId="2" ParentId="22126" CreationDate="2015-10-18T04:13:21.360" Score="12" Body="&lt;p&gt;Rotating the propeller of the Cessna 441 Conquest II is to cool the &lt;a href=&quot;https://en.wikipedia.org/wiki/Garrett_TPE331&quot;&gt;Garrett TPE331&lt;/a&gt; engine in the aircraft. From &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/14639&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On the Garrett TPE331's we were trained to spin the props after shutdown to get cooling air flowing through the engine, this was done right after shutdown. Half an hour after we did the prop spins we had go back out to the aircraft and rotate the propellers one blade width. Moving the prop one blade width rotated the engine one half turn, this was to prevent the shaft from sagging as the engine cooled causing turbine blades to rub.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The reason is given as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Direct drive turbo prop engines sometimes require this to remove residual heat from the engine because once the prop stops turning, so does the engine. When the pilot turns the prop, depending on the gear ratio, he is actually spinning the engine very fast. This helps move some of the heat out of the engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-18T04:13:21.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22132" PostTypeId="2" ParentId="21870" CreationDate="2015-10-18T08:20:47.123" Score="2" Body="&lt;p&gt;Now, these are really just a collection of stuff I have read and I am not an expert and I am writing these from vague recollection, so errors can be expected. Corrections welcome. Still thought it makes sense for me to write these, as it seems to me this type of concepts is what the question was about. These are what is usually meant when &quot;boomless supersonic&quot; is talked about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simplest way is to fly high. Lower air density means lower energy density in the boom. And greater distance means more energy will be dissipated before ground. People are always making concepts about sub-orbital shuttles that would be some where between Concorde and a ballistic missile. Would generally require a new type of engine to be practical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to attach a boom ahead of the fuselage which will have its own smaller sonic boom. This will reduce the intensity of the sonic boom of the fuselage and the sum would be smaller than without the boom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use the sonic boom and thus absorb a part of its energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use it to create compression for the engines. Basically you would trap the shock wave with the engine intakes. There would be drag and hard to imagine the same engines working well subsonic. And it would be hard to combine with generating useful lift. Also while using compression from the fuselage is normal, actually capturing the sonic boom would require the intakes to be close to the front, which would cause problems with engine design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use the energy of the shock wave to generate lift. More lift you generate, less will be left to annoy people on the ground. Basically you shape fuselage to generate more of the shock to the sides and attach to the wings a surface at an angle that reflect the shock wave downwards. Reflecting energy down will create lift. You can also have a fuselage that directly generates downwards shock waves, but in several steps for greater lift and less noise. A downside of such waverider concepts is that they only really work in supersonic, I think even a specific range of supersonic. So until you reach correct velocity you'll only have more drag.&lt;/p&gt;&#xA;" OwnerUserId="4472" LastActivityDate="2015-10-18T08:20:47.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22133" PostTypeId="2" ParentId="21861" CreationDate="2015-10-18T12:45:22.720" Score="3" Body="&lt;p&gt;In the Boeing 747 the pilots sit quite far behind the lower deck of (usually) first class seats downstairs. Quite noticeable in row 1 when the plane passes through hail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qbmsw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qbmswm.png&quot; alt=&quot;747 cutaway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11865" LastEditorUserId="97" LastEditDate="2015-10-18T17:47:03.110" LastActivityDate="2015-10-18T17:47:03.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22134" PostTypeId="1" AcceptedAnswerId="22135" CreationDate="2015-10-18T16:42:18.400" Score="9" ViewCount="33724" Body="&lt;p&gt;Some fairly busy airports that you would expect to have Class B or C airspace have class D airspace at the airport and normal class E and G airspace around that. In addition, they have an area drawn on the chart with similar dimensions to a class B or class C airspace area but they are labeled as Terminal Radar Service Area (TRSA). What is a Terminal Radar Service Area (TRSA) and what are its operational requirements?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/2hgCR.jpg&quot; alt=&quot;TRSA&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2017-01-29T22:50:09.343" LastActivityDate="2018-04-29T22:12:27.507" Title="What is a Terminal Radar Service Area (TRSA) and what are its operational requirements?" Tags="&lt;airspace&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22135" PostTypeId="2" ParentId="22134" CreationDate="2015-10-18T16:45:23.133" Score="7" Body="&lt;p&gt;A good explanation of a Terminal Radar Service Area (TRSA) can be found in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Information Manual 3-5-6&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TRSAs were originally established&#xA;  as part of the Terminal Radar Program at&#xA;  selected airports. TRSAs were never controlled&#xA;  airspace from a regulatory standpoint because the&#xA;  establishment of TRSAs was never subject to the&#xA;  rulemaking process; consequently, TRSAs are not&#xA;  contained in 14 CFR Part 71 nor are there any TRSA&#xA;  operating rules in 14 CFR Part 91. Part of the Airport&#xA;  Radar Service Area (ARSA) program was to&#xA;  eventually replace all TRSAs. However, the ARSA&#xA;  requirements became relatively stringent and it was&#xA;  subsequently decided that TRSAs would have to&#xA;  meet ARSA criteria before they would be converted.&#xA;  TRSAs do not fit into any of the U.S. airspace classes;&#xA;  therefore, they will continue to be non−Part 71&#xA;  airspace areas where participating pilots can receive&#xA;  additional radar services which have been redefined&#xA;  as TRSA Service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These airports can't be redrawn as class B or class C airspace so they became TRSAs. The airspace at the airport is class D and the airspace in the TRSA is usually class E. The operational requirements are no different than any other class E or class D airspace, but aircraft are encouraged to avail themselves and participate in the TRSA when inside its bounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should also be noted that many TRSAs have their own approach control.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-19T01:53:55.930" LastActivityDate="2015-10-19T01:53:55.930" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22136" PostTypeId="2" ParentId="22085" CreationDate="2015-10-18T17:37:22.380" Score="4" Body="&lt;p&gt;Also bear in mind that when a droplet of water approaches a supersonic airplane windshield, it first encounters a supersonic skin layer of air, which would tend to buffer and deflect some component of the force before it hit the windshield itself.  That is not to say that objects are prevented from hitting the glass...they do it all the time...but rather to say that much of the force will be dissipated, diminishing the urgency of the problem.&lt;/p&gt;&#xA;" OwnerUserId="9782" LastActivityDate="2015-10-18T17:37:22.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22137" PostTypeId="1" CreationDate="2015-10-18T17:48:16.583" Score="8" ViewCount="1274" Body="&lt;p&gt;In the case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603&quot;&gt;Aeroperu Flight 603&lt;/a&gt;, a fatal crash was caused by duct tape that was accidentally left over some or all of the static ports on the underside of the fuselage after the aircraft was cleaned. As the static ports are critical to the operation of virtually all of those flight instruments that provide aerodynamic data regarding airspeed, altitude and vertical speed to the pilots and to the aircraft's computers, this bit of duct-tape caused the total failure of multiple basic flight instruments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another crash was caused for a similar reason: pitot tubes that were blocked by an insect led to flight instrument failure, and later, a tragic crash. This was &lt;a href=&quot;https://en.wikipedia.org/wiki/Birgenair_Flight_301&quot;&gt;Birgenair Flight 301&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These accidents happened in the mid-1990s. Today, two decades on, are there better systems in place to ensure that static ports or pitot tubes don't get blocked, causing instrument failure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 1: In both these flights, the pre takeoff checks missed out on the blocked static ports/pitot tubes. Human error clearly happened at this stage. Question is, have an steps been taken to make the flight instruments proof to this particular human error?&lt;/p&gt;&#xA;" OwnerUserId="11411" LastEditorUserId="3386" LastEditDate="2017-05-11T16:37:27.543" LastActivityDate="2017-05-11T16:37:27.543" Title="What steps have been taken to rule out instrument failure due to blocked static ports or pitot tubes?" Tags="&lt;safety&gt;&lt;accidents&gt;&lt;flight-instruments&gt;&lt;accident-investigation&gt;&lt;pitot-static&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22138" PostTypeId="2" ParentId="22137" CreationDate="2015-10-18T18:29:47.940" Score="2" Body="&lt;p&gt;A clogged static port is a little bit more difficult to recognize on takeoff than a pitot port being cligged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pitot was clogged, during takeoff there would be either no indication of airspeed or an extremely low value.  The pilot monitoring should recognize this during takeoff and call for an abort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If &lt;strong&gt;all&lt;/strong&gt; the static ports are clogged, the pilots would only recognize it after takeoff.  Without accurate altitude info, it would be difficult to land safely in IMC conditions.  The transponder altitude and altitude input to a non-WAAS GPS would inaccurate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all the airplanes I fly, each Air Data Computer has a static port on each side of the airframe to preclude a simple piece of tape of causing disaster.  Not only that, there is usually another static port that is just for the standby instruments, airspeed and altimeter.  Making something that happened before less likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @Freeman states, a thorough preflight should catch those issues.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-18T18:29:47.940" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22139" PostTypeId="1" AcceptedAnswerId="22142" CreationDate="2015-10-18T19:36:02.567" Score="19" ViewCount="2746" Body="&lt;p&gt;This might be &quot;yet another lost comms questions&quot;, but I've tried to read a lot and there are different answers everywhere. Here's the scenario:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The flight plan as filed is - &lt;strong&gt;KSSI SSI V441 MONIA GNV OCF V581 DADES KTPA&lt;/strong&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm taking off from an uncontrolled airport - &lt;strong&gt;KSSI&lt;/strong&gt; to fly to &lt;strong&gt;KTPA&lt;/strong&gt; (&lt;em&gt;ICAO IDs&lt;/em&gt;). The current weather at KSSI is &lt;strong&gt;003 OVC and 2 SM&lt;/strong&gt;. I call MACON FSS for my clearance on 121.5, and here's what I get -&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MACON FSS: &quot;ATC clears N123CW to KTPA Direct SSI and then as filed, climb and maintain 4000 expect 8000 two-zero minutes after departure, departure control will be 126.75, squawk 1234. Released for departure, clearance void if not off by 20:45, time now 20:30, frequency change to advisory approved.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After read back, I take off exactly at 20:35 and after a couple minutes I contact Jax Center on 126.75 as I'm crossing 1300ft. I hear no other traffic on the frequency, and I try to contact them 2 more times while I'm heading direct to the SSI VOR. I try to contact MACON FSS with whom I'd just spoken a few minutes ago - and I hear nothing back. I try a couple of other frequencies that I can get from charts - no luck anywhere. I'm in complete IMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I know that I've lost my radio communications capabilities and hence squawk 7600, and figure out my route and altitude to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was cleared direct to the SSI VOR, and then as filed. Looking at &quot;AVEF&quot;, ATC expects me to fly the route I filed. Looks good - no problems here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was asked to climb and maintain 4000ft, and expect 8000ft 20mins after departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at &quot;MEA&quot;, ATC expects me to be at 8000ft since it's the highest amongst the Minimum En-route Altitude, the expected altitude (which is n/a) and the assigned altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm still at 2400ft, climbing to 4000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) When should I start my climb to 8000ft? Should I level off at 4000ft and wait until 20:55 (which is 20 minutes after my departure time) before initiating my climb, or does ATC expect me to be at 8000ft by 20:55?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Along my route (not immediately after departure, but after a while), for e.g. at the GNV VOR, if I briefly enter VMC, should I go ahead and land at the nearest airport as practicable or should I still continue through my route? I do know that the regulations advise to land as practicable when you're in VMC, but if the airspace ahead is being cleared for you when you're under IFR, is it advised to try and land into VFR traffic who have no idea that you're coming-in out of nowhere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Appreciate all the answers. Thank you!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS - Here's the Low-Enroute chart for quick reference:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vbVRL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vbVRL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11136" LastActivityDate="2018-07-22T15:29:06.127" Title="Lost radio communication after take-off in IMC - what are my options?" Tags="&lt;radio-communications&gt;&lt;instrument-flight-rules&gt;&lt;lost-communications&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22141" PostTypeId="1" AcceptedAnswerId="22154" CreationDate="2015-10-19T00:00:12.610" Score="13" ViewCount="4063" Body="&lt;p&gt;I am a student pilot, and would like to record my training flights to look back on. I do not have a Go-Pro, and do not want to fork over the money for one. I do however, own an iPhone 6, that has a pretty good camera. I was wondering if anyone had some ideas as to how I could mount my phone in order to record my flights? I thought maybe a suction mount would be best, as I could mount it behind my shoulder on the back of the glass cockpit (Cessna 152)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If possible, it would be better if it could record my control inputs throughout the flight. Please let me know if anyone has found a working solution in the past.&lt;/p&gt;&#xA;" OwnerUserId="11873" LastEditorUserId="167" LastEditDate="2016-02-10T01:59:46.427" LastActivityDate="2017-09-04T14:45:14.730" Title="How can I mount my iPhone 6 in the cockpit to record my flights?" Tags="&lt;cessna-152&gt;&lt;modifications&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22142" PostTypeId="2" ParentId="22139" CreationDate="2015-10-19T01:51:55.313" Score="15" Body="&lt;p&gt;The answers to these questions can be found in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM&lt;/a&gt; in section 6-4-1. All quotes are from that page.&lt;/p&gt;&#xA;&lt;p&gt;To the first question, you should expect to receive a clearance to 8,000 feet twenty minutes after departure; therefore, don't climb above 4,000 until that time. If you are still in radio contact after 20:55, the &amp;quot;expect&amp;quot; portion of the clearance expires:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If the pilot received an “expect further clearance” containing a higher altitude to expect at a specified time or fix, maintain the highest of the following altitudes until that time/fix:&lt;/p&gt;&#xA;&lt;p&gt;(1)   the last assigned altitude; or&lt;/p&gt;&#xA;&lt;p&gt;(2)  the minimum altitude/flight level for IFR operations.&lt;/p&gt;&#xA;&lt;p&gt;Upon reaching the time/fix specified, the pilot should commence climbing to the altitude advised to expect. If the radio failure occurs after the time/fix specified, the altitude to be expected is not applicable and the pilot should maintain an altitude consistent with 1 or 2 above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For the second question, the answer comes down to the definition of &amp;quot;briefly&amp;quot;. Is your hole big enough for you to get under the clouds, and is the ceiling high enough that you can remain VMC to land? If so, you should do so. But if you just briefly see the ground, or aren't confident that you could safely fly VFR to a suitable airport, then you should maintain IFR and continue flying your clearance. You may inconvenience a few controllers, but if you leave your cleared route only to discover that your intended airport is socked in, getting back to your route to resume your original destination puts you potentially low to the ground, and not along the route that ATC is expecting you:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Pilots should recognize that operation under these conditions may unnecessarily as well as adversely affect other users of the airspace,&#xA;since ATC may be required to reroute or delay other users in order to&#xA;protect the failure aircraft. However, it is not intended that the requirement to “land as soon as practicable” be construed to mean “as soon as possible.” Pilots retain the prerogative of exercising their best judgment and are not required to land at an unauthorized airport, at an airport unsuitable for the type of aircraft flown, or to land only minutes short of their intended destination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;That said, VFR traffic should always be looking for other aircraft - with and without radio contact. Radios are not required equipment, at least at non-towered airports, so landing among VFR traffic without a radio should not be a big deal.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-19T01:51:55.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22143" PostTypeId="2" ParentId="18760" CreationDate="2015-10-19T05:42:52.280" Score="8" Body="&lt;p&gt;As @reirab explained, &quot;N&quot; registration numbers are generally used for civilian aircraft.  However, there are some notable exceptions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_Dash_7&quot; rel=&quot;noreferrer&quot;&gt;de Havilland DHC-7&lt;/a&gt; (aka &quot;Dash-7&quot;, variously nomenclatured O-5A, EO-5B/C, or RC-7B) is used by the United States Army as its &lt;a href=&quot;http://www.globalsecurity.org/intell/systems/arl.htm&quot; rel=&quot;noreferrer&quot;&gt;Airborne Reconnassaince-Low&lt;/a&gt; manned aerial imagery intelligence platform.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NAYFo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NAYFo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Akradecki&quot; rel=&quot;noreferrer&quot;&gt;Alan Radecki&lt;/a&gt; / &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/8/84/Arl-dash7-N158CL-010515-01.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Foundation&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another de Havilland, this one a &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter&quot; rel=&quot;noreferrer&quot;&gt;DHC-6&lt;/a&gt;, is used by the Air Force Academy's parachuting team:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mbsAe.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mbsAe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: &lt;a href=&quot;https://www.flickr.com/photos/ian_tate/&quot; rel=&quot;noreferrer&quot;&gt;Ian Tate&lt;/a&gt; / &lt;a href=&quot;https://www.flickr.com/photos/ian_tate/16027885459&quot; rel=&quot;noreferrer&quot;&gt;Flickr&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dover AFB's 436 Force Support Squadron employs several Cessnas at their Aero Club, used for &lt;a href=&quot;http://www.doverafb436fss.com/pages/main-website/leisure-activities/aero-club/rates.php&quot; rel=&quot;noreferrer&quot;&gt;flight training&lt;/a&gt;.  One of them made the news when it made an emergency landing &lt;a href=&quot;http://www.flyingmag.com/technique/accidents/air-force-cessna-ends-delaware-highway&quot; rel=&quot;noreferrer&quot;&gt;onto a local highway&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pnrNO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pnrNO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: Adrian R. Rowan / &lt;a href=&quot;http://www.dover.af.mil/shared/media/photodb/photos/2012%5C07%5C120329-F-MM982-002.jpg&quot; rel=&quot;noreferrer&quot;&gt;Dover AFB&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are just a start.  Getting creative with search queries, you can also find &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/Name_Results.aspx?Nametxt=DEPARTMENT%20OF%20THE%20ARMY&amp;amp;sort_option=1&amp;amp;PageNo=1&quot; rel=&quot;noreferrer&quot;&gt;hundreds&lt;/a&gt; of &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/Name_Results.aspx?Nametxt=DEPARTMENT%20OF%20DEFENSE&amp;amp;sort_option=1&amp;amp;PageNo=1&quot; rel=&quot;noreferrer&quot;&gt;other&lt;/a&gt; &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/Name_Results.aspx?Nametxt=DEPARTMENT%20OF%20THE%20NAVY&amp;amp;sort_option=1&amp;amp;PageNo=1&quot; rel=&quot;noreferrer&quot;&gt;aircraft&lt;/a&gt; &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/Name_Results.aspx?Nametxt=UNITED%20STATES%20ARMY&amp;amp;sort_option=1&amp;amp;PageNo=1&quot; rel=&quot;noreferrer&quot;&gt;listed&lt;/a&gt; in the &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/name_inquiry.aspx&quot; rel=&quot;noreferrer&quot;&gt;FAA registration database&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Virtually all of these are very special-purpose aircraft, with no munitions or other armament (aside from chaff/flare as in the case of the Dash 7).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;And although not technically military (yet), it is common for developmental aircraft to be given civilian registration numbers during flight testing phases prior to final delivery.  This prototype &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_KC-46_Pegasus&quot; rel=&quot;noreferrer&quot;&gt;KC-46A&lt;/a&gt;, painted mostly in military-style &quot;livery&quot;, has registration number N461FT.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4I3dw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4I3dw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image credit: Ken Fielding / &lt;a href=&quot;https://en.wikipedia.org/wiki/File:N461FT_4_Boeing_767-2C%282LK%29-KC-46A_Boeing_Aircraft_Co_%28USAF%29_PAE_29JUL15.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="6919" LastActivityDate="2015-10-19T05:42:52.280" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22144" PostTypeId="1" AcceptedAnswerId="22292" CreationDate="2015-10-19T07:37:16.690" Score="10" ViewCount="875" Body="&lt;p&gt;For a while now I've noticed an exclamation mark on the ACARS inflight page of the B737NG at the beginning of a flight. It is located in the top left corner of the page and it just disappears after a while. I've been searching high and low what it means but can't find it.&#xA;Any ideas?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oNYKX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oNYKX.jpg&quot; alt=&quot;ACARS page with !&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11876" LastEditorUserId="19" LastEditDate="2016-07-07T16:34:58.357" LastActivityDate="2016-07-07T16:34:58.357" Title="What is the significance of the exclamation mark (!) on ACARS page of a Boeing 737?" Tags="&lt;boeing-737&gt;&lt;acars&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22145" PostTypeId="2" ParentId="12644" CreationDate="2015-10-19T07:53:54.550" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can Russian-built tankers refuel NATO probe-and-drogue receivers, and&#xA;  vice versa?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Russian system is called UPAZ and its manufacturer Zvezda states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;The nozzle assemblies are adapted to the refueling pods of foreign aircraft&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://777.zvezda-npp.ru/engl/zaprav.html&quot; rel=&quot;noreferrer&quot;&gt;http://777.zvezda-npp.ru/engl/zaprav.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically this means a bog-standard Russian Mig/Sukhoi cannot plug into a Western tanker aircraft without some change in the configuration. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Say, a US Navy F/A-18E getting a helping hand from an Indian Air Force&#xA;  Il-78MKI&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Indian IL-78s have Israeli-made refuelling equipment so I can't say whether it's compatible with F/A-18E. However, from what I know, India has been using this Israeli equipment to refuel its MiGs and Sukois just fine.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2015-10-19T08:19:03.853" LastActivityDate="2015-10-19T08:19:03.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22146" PostTypeId="1" AcceptedAnswerId="22147" CreationDate="2015-10-19T08:01:05.607" Score="4" ViewCount="147" Body="&lt;p&gt;I remember hearing about a British airport that had two approaches that were used on alternating weeks. They implemented this pilot project (no pun intended) so that different houses would be overflown each week, giving residents the impression that noise from the airport was reduced. What airport was this?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastEditorUserId="19" LastEditDate="2016-07-29T08:40:19.513" LastActivityDate="2016-07-29T08:40:19.513" Title="Which UK airport uses different approaches for noise reduction?" Tags="&lt;airport&gt;&lt;approach&gt;&lt;noise-reduction&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22147" PostTypeId="2" ParentId="22146" CreationDate="2015-10-19T09:24:14.960" Score="5" Body="&lt;p&gt;Apparently it's called Runway Alteration. The only hits I got were referring to &lt;a href=&quot;http://www.heathrow.com/noise/heathrow-operations/runway-alternation&quot; rel=&quot;nofollow&quot;&gt;Heathrow airport&lt;/a&gt;, so my guess is this is the only airport that uses this procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, the alternation is in two ways: per part of the day, and per week.&#xA;During week 1, from 06:00 to 15:00 runway 27L is used, and from 15:00 until last departure 27R is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The week after this, the things are reversed:&#xA;From 06:00 to 15:00 runway 27R is used, and from 15:00 until last departure 27L is used.&#xA;So the people living under the approach of 27L will have noise in the first part of the day in week 1, and during the second part of the day in week 2.&#xA;See the full programme &lt;a href=&quot;http://www.heathrow.com/file_source/HeathrowNoise/Static/Runway_Alternation_Programme-2015.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is influenced by the six factors below (taken from the same source):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Daytime patterns of runway alternation are different to night-time    patterns: at night there are only a handful of landings and very few take-offs.&lt;/li&gt;&#xA;  &lt;li&gt;Aircraft land and take off    into the wind, so the &lt;a href=&quot;http://www.heathrow.com/noise/heathrow-operations/wind-direction&quot; rel=&quot;nofollow&quot;&gt;wind direction&lt;/a&gt; has a big effect on flight patterns.&lt;/li&gt;&#xA;  &lt;li&gt;Government policy currently favours aircraft taking off    towards the west. Even when the wind blows from the east, aircraft    could&#xA;  still fly in from east and take off towards the west. This is because we have a &lt;a href=&quot;http://www.heathrow.com/noise/heathrow-operations/cranford-agreement&quot; rel=&quot;nofollow&quot;&gt;westerly preference&lt;/a&gt;.&lt;/li&gt;&#xA;  &lt;li&gt;A historical restriction means    that aircraft cannot take off towards the east from the northern    runway. This is because of the &lt;a href=&quot;http://www.heathrow.com/noise/heathrow-operations/cranford-agreement&quot; rel=&quot;nofollow&quot;&gt;Cranford Agreement&lt;/a&gt;. &lt;/li&gt;&#xA;  &lt;li&gt;The hour between    06:00 and 07:00 is the busiest time of the day for arrivals so we are   able to use both runways for landings.&lt;/li&gt;&#xA;  &lt;li&gt;Occasionally we have to suspend    runway alternation for airfield maintenance, in response to bad    weather or when air-traffic control&#xA;  want to avoid a build-up of    arriving aircraft.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Actually, alternation also occurs for night flights, but then in 4 one-week periods.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2015-10-19T14:18:40.520" LastActivityDate="2015-10-19T14:18:40.520" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22148" PostTypeId="1" AcceptedAnswerId="22160" CreationDate="2015-10-19T10:31:55.333" Score="18" ViewCount="2766" Body="&lt;p&gt;Do current composite materials handle bird strikes better than their predecessors? Or they are not part of forward-facing components/areas? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the Boeing Dreamliner or the Airbus A350-XWB.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="15311" LastEditDate="2020-04-12T12:59:38.493" LastActivityDate="2020-04-12T12:59:38.493" Title="Are composite materials, which are being widely used in newer aircraft, better at handling bird strikes?" Tags="&lt;aerospace-materials&gt;&lt;bird-strike&gt;&lt;composite-materials&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="22149" PostTypeId="2" ParentId="22148" CreationDate="2015-10-19T11:27:38.957" Score="4" Body="&lt;p&gt;May be it's better to answer the question the other way around. There are regulations which need to be followed. This also includes bird-strikes. In order to get certified all the requirements have to be accomplished.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason new materials are used is because they feature desirable attributes (they are for example lighter or maybe cheaper) while achieving the requested properties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not only a specific property of the material which makes it sustaining a bird strike but also the way the whole part was designed by the engineers. Depending on the material this design process might be different and might contain certain challenges. However, the final part will only be as strong as the regulations require. This will be true for aluminium, titanium or composite materials.&lt;/p&gt;&#xA;" OwnerUserId="11294" LastActivityDate="2015-10-19T11:27:38.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22150" PostTypeId="2" ParentId="22148" CreationDate="2015-10-19T12:21:03.173" Score="19" Body="&lt;p&gt;Out of the box, no. They are worse at handling birdstrikes. But with some thought they can be made much better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All materials have an elastic range of deformation, and if that is not exceeded, they will assume their original shape without damage. Composites fail if this range is exceeded. First the fibers with the highest elongation fail, which enables the other fibers to take more load, but at some point too few fibers remain, and the part fails catastrophically. This is audible: The first small failures cause a faint crackling, and the eventual failure a loud bang.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Metals add a plastic deformation before ultimate failure, and this enables them to absorb a lot of energy in the process. Since energy is force times distance, the small elastic deformation will not absorb much energy. However, the plastic deformation is magnitudes bigger and makes metals the much better energy absorbers. Even a deformed structure can take a sizable fraction of the load it took before deformation. A birdstrike will cause a dent, but the rest of the structure will not see much of the load since the dent-forming could absorb a lot of energy. However, the changed contour can provoke changed aerodynamic loads, so new failure modes might result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Impact loads on composites have a second disadvantage: The impact creates shockwaves which travel through the structure and cause &lt;a href=&quot;https://en.wikipedia.org/wiki/Delamination&quot;&gt;delamination&lt;/a&gt; (separation between fibers and resin matrix) when they hit a boundary. Therefore, the biggest damage occurs on the opposite side of the impact. A birdstrike might not leave a visible dent on the outside, but can shatter the material on the opposite side such that the structure will break at a fraction of the load it would have carried without the bird strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, some composite wings use metallic leading edges to protect the composite structure from birdstrikes. But also the composite structure itself can be improved: If very tough fibers like &lt;a href=&quot;http://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/fibers/brands/kevlar.html&quot;&gt;Kevlar&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Ultra-high-molecular-weight_polyethylene#Fiber&quot;&gt;Spectra&lt;/a&gt; are added, the impact energy will not break those fibers, and the load will be distributed over much more of the resin matrix. This will delay delamination, and when it happens, it will be spread over a bigger area and cause the fibers to break at multiple locations. The energy needed for the widespread delamination and the multiple fiber failures will increase the energy absorption dramatically. This structure must be designed as a protective armor, so the load-carrying structure below is not affected. Proper crashworthy design with composites allows to make the structure even tougher than a comparable metallic structure.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="4474" LastEditDate="2015-10-19T18:08:57.493" LastActivityDate="2015-10-19T18:08:57.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22151" PostTypeId="1" CreationDate="2015-10-19T12:24:27.303" Score="5" ViewCount="13999" Body="&lt;p&gt;As far as I know, all turboprop engines have mechanical continuity between the engine and the propeller except for the Pratt &amp;amp; Whitney Canada PT6 family of engines. What is the correct term for the setup the PT6 uses to power the propellor and how does the PT6's design differ from other turboprop engines?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-19T14:52:00.020" LastActivityDate="2017-03-15T12:54:22.717" Title="How does the Pratt &amp; Whitney Canada PT6 differ from other turboprop engines?" Tags="&lt;turboprop&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22153" PostTypeId="1" AcceptedAnswerId="22159" CreationDate="2015-10-19T12:56:51.237" Score="6" ViewCount="1804" Body="&lt;p&gt;When a composite structure is hit, the impact causes shockwaves which travel through the structure, and cause delamination. Delamination reduces the strength of the composite structure and may cause the structure to break at a fraction of the load it would have carried before the impact. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delamination and its ill-effects can be reduced, for instance by adding metal at strategic points of the aircraft. But once delamination occurs, how can it be detected? What measure (if any) have been implemented to detect delamination on aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3775" LastActivityDate="2015-10-19T14:50:52.557" Title="Can delamination be detected early?" Tags="&lt;safety&gt;&lt;aircraft-structures&gt;&lt;composite-materials&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22154" PostTypeId="2" ParentId="22141" CreationDate="2015-10-19T12:59:17.203" Score="17" Body="&lt;p&gt;&lt;strong&gt;UPDATE  9/4/2017&lt;/strong&gt;&#xA;I'm thrilled this post has been so helpful for so many people. As such, I wanted to  update it with more details and more current links in case people are interested. Enjoy!&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;You could have a lot of fun, and get a lot out of reviewing the footage of your lessons. I'd look into a suction cup mount as you are already considering. When buying a suction cup mount, make sure you get one that is &amp;quot;beefier&amp;quot; than you expect you need. Whatever you do, make sure you share your videos online, your video might even get someone else interested in aviation!&lt;/p&gt;&#xA;&lt;p&gt;Below are the details of doing what you asked. You might be able to buy a used, older model gopro for a comparable price - but I'd actually argue your phone is probably a better option.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;What to buy:&lt;/strong&gt;&#xA;(this all actually gets kind of expensive, but is &lt;em&gt;still&lt;/em&gt; cheaper than buying a go pro and accessories)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Must have:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;To get GoPro functionality from your iphone&lt;/strong&gt;, you'd need a mount and a case:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://amzn.to/1ZQDx7q&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/1ZQDx7q&lt;/a&gt; (Optrix Super Sucker Mount)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://amzn.to/1MyN1uc&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/1MyN1uc&lt;/a&gt; (Case)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;This is a mount that mimics the functionality of a go-pro mount. It also let's you know if pressure is dropping in the suction cup as you climb.&lt;/p&gt;&#xA;&lt;p&gt;If you ever feel brave enough you could even stick this to your wing!&lt;/p&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/1GmeYbU&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/1GmeYbU&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;The view angle probably is not wide enough. This inexpensive kit will apply a wide angle to your iphone. I'd make sure your case/mount doesn't preclude using one of these.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Best alternative camera to GoPro:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2vZsQEx&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2vZsQEx&lt;/a&gt; (Garmin Ultra Virb 30)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;I love the aviation data overlay of this camera. It works very well and helps debriefing a lot. I personally prefer this over my GoPro because it includes that data.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Best GoPro options:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2xJKn67&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2xJKn67&lt;/a&gt; (GoPro Hero5 Black)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;4k resolution @ 30FPS, 12MP quality is great. I use this mainly for wing mounted shots.&lt;/p&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2eDiQi3&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2eDiQi3&lt;/a&gt; (GoPro Hero5 Session)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;The nice thing about the session series is they are small and super simple to operate. I use this camera to point inside the cabin, on the side windows. It is nice because it doesn't block as much of my view outside, even in a mount on suction cups.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Important Accessories:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/1ZQERqT&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/1ZQERqT&lt;/a&gt; (Zoom H1)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;I use this to record ATC/Headset audio. It is easy to have it recorded to its own device and lets me have better control over the audio recordings than if it was part of a video file. The audio is oftentimes more useful than the video alone, especially with your instructor explaining things to you. Having a separate device also reduces your point of failure risk if you have a camera battery die.&lt;/p&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2wAg29z&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2wAg29z&lt;/a&gt; (Headset cable to record audio)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;You need this cable to &amp;quot;grab&amp;quot; audio from your headset jack to record it to a camera or external recorder. (&lt;em&gt;Note- the Garmin Virb 30 Aviation bundle includes this&lt;/em&gt;)&lt;/p&gt;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2wAo1Uh&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2wAo1Uh&lt;/a&gt; (External Battery)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;You will be running out of battery fast if you record HD video for any length of time. This external charger will keep you from running out of battery.&lt;/p&gt;&#xA;&lt;ol start=&quot;4&quot;&gt;&#xA;&lt;li&gt;ND (Prop) Filters (remove the weird prop strobing from your footage)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;(&lt;em&gt;Note- the Garmin Virb 30 Aviation bundle includes this&lt;/em&gt;)&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2xJhxm9&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2xJhxm9&lt;/a&gt; (GoPro Hero5 Black ND Filter)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://amzn.to/2exTIFG&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/2exTIFG&lt;/a&gt; (GoPro Hero5 Session ND Filter)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;Placement:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The best place to put it would be between the seats on the ceiling pointing landscape style towards the instrument panel. This would give you a view of all of your instruments and maybe even a bit of the horizon. At first, we all struggle to use the horizon as a reference instead of instruments, so putting the camera close to head level might help develop a good sight picture.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ivv1m.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ivv1m.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://youtu.be/ApG1hOnDqBc?t=23m1s&quot; rel=&quot;noreferrer&quot;&gt;Here's a video using the angle I am referring to.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Unless you set up a second camera, you are unlikely to get rudder input on film. This video shows a good example of that angle, but might be impossible while getting dual instruction.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4dNhd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4dNhd.jpg&quot; alt=&quot;&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://youtu.be/dfXT38YIO6g?t=4m39s&quot; rel=&quot;noreferrer&quot;&gt;Video showing rudder control input on takeoff&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Words of caution:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Make sure your filming doesn't distract you. This is really serious and not something to shrug off. Remember, you don't want the FAA to have footage to shove in your face of you being reckless.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;&lt;strong&gt;Make sure you don't damage the aircraft with the mount.&lt;/strong&gt;&lt;/em&gt; The windshields in particular are vulnerable to being squeezed out of shape from the pressure in the suction cup, especially if they are hot. I have seen some indented windshields recently due to gopro mounts, which makes it very hard to get a normal sight picture (imagine looking through a fun house mirror).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;&#xA;Another issue I recently saw was a result of someone using this camera: &lt;a href=&quot;http://amzn.to/1oos68G&quot; rel=&quot;noreferrer&quot;&gt;http://amzn.to/1oos68G&lt;/a&gt;. The camera has a built in rare earth magnet which made mounting it very easy. The problem was, it was impacting the magnetic compass - so be aware if you get a magnetic mount to make sure your compass is not affected by it being placed in the cockpit! When attached to the overhead speaker we saw no visible impact on the compass, but worth keeping an eye on.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Take a look on youtube at some popular pilot channels to see how they record. From there, you can pick your favorite angles and splice a film together.&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-09-04T14:45:14.730" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22155" PostTypeId="1" AcceptedAnswerId="22156" CreationDate="2015-10-19T13:00:07.610" Score="27" ViewCount="3600" Body="&lt;p&gt;I get alerts whenever a plane squawks &lt;code&gt;7700&lt;/code&gt;, using a popular flight tracker application. It happens quite frequently that the aircraft, reported to squawk &lt;code&gt;7700&lt;/code&gt;, in actuality squawks &lt;code&gt;7550&lt;/code&gt; or some other &lt;em&gt;benign&lt;/em&gt; number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would cause this? Are the instruments such that it starts on &lt;code&gt;0000&lt;/code&gt;, and allows setting each digit with a dial you can turn both left and right?&lt;/p&gt;&#xA;" OwnerUserId="2448" LastEditorUserId="167" LastEditDate="2015-10-20T03:00:55.740" LastActivityDate="2019-02-09T11:33:40.897" Title="What could cause an inadvertent squawking of 7700?" Tags="&lt;radio-communications&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22156" PostTypeId="2" ParentId="22155" CreationDate="2015-10-19T13:17:37.717" Score="34" Body="&lt;p&gt;A transponder in most planes look something like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JB0iq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JB0iq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.bendixking.com/Products/Discontinued/KT-76A&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The code is changed by turning the knobs beneath the numbers. Lets say you are assigned 5700 as your code but your previous code was 7456. If you are careless or start from the right most knob your transponder will briefly be set in 7700 until the most significant digit is changed. If the radar does a pass (&lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_transponder_interrogation_modes&quot; rel=&quot;nofollow noreferrer&quot;&gt;interrogation&lt;/a&gt;) at that time ATC will momentarily receive a 7700. Some people say you should put your transponder in standby (SBY) mode when changing codes to avoid this happening.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some GA planes (and even some larger planes) have newer digital interface transponders like this one, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tZmqY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tZmqY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.avionicslist.com/articles/garmin_gtx_330.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These make it a bit harder to pass through the codes since you are not turning knobs but in bumpy air you could accidentally double tap a number. For example lets say you are assigned 7003 in bumpy air. You go to hit the 7 and accidentally double tap the button. Then you type in the 00 and your code is complete by the time you hit the 3. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some looking it seems that larger aircraft user a transponder like this one,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oBelM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oBelM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://web.archive.org/web/20151020073519/http://www.cpflight.com/sito/prodotti.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case you will see a similar case to the first transponder listed. If its not in STBY while switching you inevitable have to pass over 7700, 7600 or 7500 to get to some codes. If an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_transponder_interrogation_modes&quot; rel=&quot;nofollow noreferrer&quot;&gt;interrogation&lt;/a&gt; happens at that time it may cause the results you mention. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of switching to STBY mode, the only documentation I can find about keeping the transponder in altitude reporting mode is &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2015/SAFO15006.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this document&lt;/a&gt; which states &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;operators and pilots of the need to ensure that transponders are in the&#xA;  altitude reporting mode whenever their aircraft is on an airport movement area at all airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This was issued in May of 2015 and seems to be related to the ground surveillance systems being installed at airports. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA FAR touches on transponder operation in &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.215&quot; rel=&quot;nofollow noreferrer&quot;&gt;S91.215&lt;/a&gt; and part C reads &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Transponder-on operation. While in the airspace as specified in paragraph (b) of this section or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with Sec. 91.413 of this part shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This section simply states that you must &quot;operate&quot; the transponder on the code assigned while in required airspace. That seems a little vague and does not completely exclude putting it in STBY mode to switch codes.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="753" LastEditDate="2017-10-12T11:13:14.760" LastActivityDate="2017-10-12T11:13:14.760" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22157" PostTypeId="2" ParentId="22151" CreationDate="2015-10-19T13:52:14.370" Score="6" Body="&lt;h2&gt;Split Shaft&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Several turboprop engines, including the PT6 turboprop engine, use an &lt;a href=&quot;https://en.wikipedia.org/wiki/Epicyclic_gearing&quot; rel=&quot;noreferrer&quot;&gt;epicyclic&lt;/a&gt; gearbox only, many other turboprop engines use a multishaft &lt;a href=&quot;https://en.wikipedia.org/wiki/Gearbox&quot; rel=&quot;noreferrer&quot;&gt;gearbox&lt;/a&gt;. The latter usually results in the propeller axis being offset from the turbine axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In common with some other engines, the PT6 turbine is also reversed. This facilitates the &lt;strong&gt;split-shaft&lt;/strong&gt; arrangement where the engine and propeller are driven by separate (but in-line) shafts, each connected to their own turbine wheel.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;PT6&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IYbxb.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IYbxb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image: P&amp;amp;W&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4d1Ii.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4d1Ii.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image:&lt;a href=&quot;http://12charlie.com/&quot; rel=&quot;noreferrer&quot;&gt;12Charlie&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;A contrasting and common design&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Khg3X.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Khg3X.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image:&lt;a href=&quot;http://12charlie.com/&quot; rel=&quot;noreferrer&quot;&gt;12Charlie&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-10-19T16:01:18.730" LastActivityDate="2015-10-19T16:01:18.730" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22158" PostTypeId="2" ParentId="22153" CreationDate="2015-10-19T13:54:58.187" Score="5" Body="&lt;p&gt;There are multiple non-destructive methods to detect delamination in composite materials.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case the delamination occurs on the surface, it can be easily found by visual inspection. This is the easiest method to detect delaminations; however, this is useful only if the delaminations are visible from the outside (i.e. they are on the surface), which is rarely the case, at-least in aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ultrasonic testing- In this method, ultrasonic waves are passed through the surface of the material and the response is monitored. Depending on the condition of the material (whether it has defect or not), the ultrasonic waves behave differently. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QGpf7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGpf7.jpg&quot; alt=&quot;Ultrasonic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: cnde.iastate.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ultrasonic method used can be through scan (with the transmitter and reciever on the opposite sides of the part) or pulse echo method, where the transmitter/reciever 'listens' to the ultrasonic sound reflected back from the defect or the other end of the part. There are three main methods of ultrasonic scanning in use:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The A-scan presentation displays the amount of received ultrasonic energy as a function of time. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The B-scan presentations is a profile (cross-sectional) view of the part. Here, the travel time of the sound energy is displayed along the vertical axis and the linear position of the transducer is displayed along the horizontal axis.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The C-scan presentation provides a plan-type view of the location and size of defects. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tap test, using a coin or an instrumented hammer- This is the most widely used method in the field as it requires minimal instrumentation. However, it requires a trained operator, who can distinguish between the normal and delaminated composite from the sound. Instrumented hammers are also available, where the frequency response of the part can be analyzed for identifying defects.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KtaOt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KtaOt.png&quot; alt=&quot;Tap Test&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: amumagazine.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Thermography- Here, an energy source is used to produce thermographic contrast between tthe defect on the part. This is useful in detecting shallow subsurface defects, but is rarely used in field operations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Knon9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Knon9.jpg&quot; alt=&quot;Thermography&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Infrared thermography Source: seattleinfrared.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;X-Ray radiography (or CT scan in some cases)- This is a very accurate method for detecting internal defects; however, the equipment requirements mean that it is usually used in the place of the OEM, though some field equipment is available for military uses.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0r2U9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0r2U9.jpg&quot; alt=&quot;Fatigue Crack under X ray&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fatigue crack under X-Ray, Source: vidisco.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some other methods like the acoustic emission and lasers, which also can be used for detecting delamination. The table below gives some of the methods used for detecting defects &lt;em&gt;in a manufacturing environment&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iDZN4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iDZN4.png&quot; alt=&quot;Comparison chart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: amumagazine.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-19T14:50:52.557" LastActivityDate="2015-10-19T14:50:52.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22159" PostTypeId="2" ParentId="22153" CreationDate="2015-10-19T14:08:27.647" Score="5" Body="&lt;p&gt;The most obvious way is to de-assemble the structure and look inside. This leaves the least amount of doubt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there are many ways to do this without destruction.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ultrasonic: The echo of the ultrasonic ping comes back early (reflection at an inner layer) and in multiple echoes (due to the many boundaries inside the delaminated area). This is easy to do and needs access only from one side, but the interpretation of the signal needs some training.&lt;/li&gt;&#xA;&lt;li&gt;X-ray, but now you need a receiver at the other side.&lt;/li&gt;&#xA;&lt;li&gt;Knocking on the surface will help with massive delamination&lt;/li&gt;&#xA;&lt;li&gt;Eigenfrequency Testing of resonant structures. If the structure is damaged, its stiffness is reduced and so is its eigenfrequency.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And there are even ways to monitor the structure in flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You can install microphones internally and let them monitor the crackling due to damage. This allows to spot damage quite precisely when the signal is run through suitable computer software.&lt;/li&gt;&#xA;&lt;li&gt;Or you put optical fibers into the structure and test whether they still transmit light. This needs quite a lot of fibers and optical terminals, though. When a crack interrupts the transmission, you can time the return of the reflected light pulses and determine the location of the damage quite precisely.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Sorry, @aeroalias, but optical inspection from the outside will only work when damage is extensive. Most damage can &lt;strong&gt;not&lt;/strong&gt; be spotted from the outside with the naked eye.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-19T14:08:27.647" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22160" PostTypeId="2" ParentId="22148" CreationDate="2015-10-19T15:09:55.647" Score="14" Body="&lt;p&gt;In general, the composite materials are poor compared to metals in impact resistance (in general, composites are not good in resisting compressive loads). This is because the metals and composites respond to impact in different ways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of metals , most of the impact energy is absorbed by the metals through plastic deformation. As the plastic region is pretty large compared to the elastic region, this means that they have a good impact resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/43ybH.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/43ybH.png&quot; alt=&quot;Plastic Range&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.spaceflight.esa.int&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the (fiber reinforced) composites undergo little plastic deformation. The response of the composites in case of impact depends on a number of characters like the speed of impact, fiber orientation etc. In case of low intensity impact, elastic deformations may appear near the impact area. A high speed impact, however, causes deteriorations of the material, which includes separation of the fibers from the matrix, matrix cracking and fiber&#xA;breaking. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zaVPn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zaVPn.jpg&quot; alt=&quot;Composite versus metal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparison of stress- strain curves of composites and metals. Image from &lt;em&gt;Circular and Square Concrete Columns Externally Confined by CFRP Composite: Experimental Investigation and Effective Strength Models&lt;/em&gt; by Riad Benzaid et. al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The absorbed energy consequent to the impact depends, among others parameters, on the fiber – resins link resistance. If this link is strong, a continuous crack may spread along the material. In the case of a weak link, the generated crack may have an irregular form, leading to a rapid separation of the fibers from the matrix and to a considerable absorption energy. However, the adhesion between the fibers and the matrix shouldn't be too weak as a low shear resistance also influences the impact behavior in  a negative manner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary mechanism is that the fibers are subjected to bending, which breaks them, consequent to which the load is transferred to the resin base, which usually cracks. The the load is transferred to the other fibers, which get damaged. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some ways to make the composites better impact resistant, like using materials like Kevlar, which has higher impact resistance. These tough materials have higher failure loads,which helps in absorbing the impact load and transferring to to the resin matrix (which carries the compressive load).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z52i0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z52i0.jpg&quot; alt=&quot;Impact Strength&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Impact strength of various composites, from &lt;em&gt;The Impact Behaviour of Composite Materials&lt;/em&gt; by Chircor Mihael et. al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The composites can also be tailored to have a better impact resistance. Also, the places where the impacts are expected, like the leading edges can be made from metals. Interestingly, both A350XWB and Boeing 787 use metals in the wing leading edges, though I'm not sure how much of this is attributable to impact resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rVPiW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rVPiW.jpg&quot; alt=&quot;B787 Composite&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.1001crash.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-19T15:44:20.303" LastActivityDate="2015-10-19T15:44:20.303" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22161" PostTypeId="1" AcceptedAnswerId="22163" CreationDate="2015-10-19T16:44:00.563" Score="16" ViewCount="4790" Body="&lt;p&gt;Two questions regarding ferry flights:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When an aircraft has to be delivered, who flies it to the destination airport? Does the manufacturer have a dedicated crew for this or is it up to the airline to send someone over?&lt;/li&gt;&#xA;&lt;li&gt;When an aircraft is sent to Victorville (Southern California Logistics Airport), who flies the plane? Is it a dedicated airline crew or is it a contracted-out service?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="1696" LastEditDate="2015-10-19T17:04:52.197" LastActivityDate="2017-11-12T16:19:37.250" Title="Who flies planes on ferry flights?" Tags="&lt;ferry-flight&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22163" PostTypeId="2" ParentId="22161" CreationDate="2015-10-19T16:54:25.447" Score="28" Body="&lt;p&gt;Ferry flights encompass much more than delivery and retirement flights.  Any time an airplane has a problem that can't be fixed on-site they can generally obtain a ferry permit to get it to an airport that the maintenance can be completed at.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the airline I worked for, all flights, including initial delivery, were conducted by pilots on our seniority list and other airlines I'm familiar with have the same requirements in their contract language.  Our airplanes were manufactured in Brazil and a crew would be take an airline flight down to the Embraer factory, accept the airplane and fly it to a US customs station and then on to our main maintenance airport.  These flights were fairly uncommon and often went to very senior and management pilots.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal ferry flights for aircraft repositioning or maintenance needs were generally done by low-seniority reserve crews because those tended to be non-scheduled activity and show up with short notice.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all cases though, at my airline, ferry flights were conducted by company pilots.  This can vary by airline and there probably isn't a universal definitive procedure common to every airline.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-10-19T16:54:25.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22164" PostTypeId="1" AcceptedAnswerId="22167" CreationDate="2015-10-19T17:02:00.243" Score="3" ViewCount="3195" Body="&lt;p&gt;For most of the newly built airport terminals I've seen, the arrival halls are located on the lower level and the departure halls are on the upper level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the benefit and disadvantage when:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Departure halls are above arrivals.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Arrival halls are above departures.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Arrivals and departures are on same level but in different places.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;How do arrival/departure locations inside the airport impact the placement of airliners at the gates?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="6886" LastEditDate="2015-10-20T03:17:25.240" LastActivityDate="2015-10-20T03:17:25.240" Title="Why have different departure hall and arrival hall locations?" Tags="&lt;airport&gt;&lt;airport-design&gt;" AnswerCount="2" CommentCount="5" ClosedDate="2015-10-20T08:02:01.553" ContentLicense="CC BY-SA 3.0" />
  <row Id="22165" PostTypeId="2" ParentId="22161" CreationDate="2015-10-19T17:05:24.030" Score="13" Body="&lt;p&gt;Usually, ferry and delivery flights have different meanings. It differs from aircraft to aircraft.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of new commercial aircraft, the delivery team from the airlines are sent to the manufacturer, where they accept and bring the aircraft to the airline location. The &lt;a href=&quot;http://www.airbus.com/company/aircraft-manufacture/how-is-an-aircraft-built/delivering-to-the-customer/&quot; rel=&quot;noreferrer&quot;&gt;delivery procedure of Airbus&lt;/a&gt; is as follows:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The delivery phase is spread over four or five days on average, dependent upon the aircraft programme. A standard delivery procedure takes place as follows:&lt;/p&gt;&#xA;&lt;p&gt;1st day: ground checks: external surfaces, bays and cabin visual inspection, static aircraft system and cockpit checks, engine tests.&lt;/p&gt;&#xA;&lt;p&gt;2nd day: acceptance flight: checks during flight of all aircraft systems (including cabin systems) and aircraft behavior in the whole flight envelope.&lt;/p&gt;&#xA;&lt;p&gt;3rd day: physical rework or provision of solutions for all technical and quality snags open in delivery.&lt;/p&gt;&#xA;&lt;p&gt;4th day: completion of technical acceptance. Technical closure of the aircraft and all associated documents attesting the aircraft’s compliance to the type certificate and conformity to the technical specification allowing the issuance of the Certificate of Airworthiness.&lt;/p&gt;&#xA;&lt;p&gt;5th day: transfer of the aircraft's title deeds to the customer airline: the aircraft changes owner. Preparation of the aircraft for the ferry flight to its home base.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For GA, ferrying is &lt;a href=&quot;http://www.bbc.com/news/magazine-34484972&quot; rel=&quot;noreferrer&quot;&gt;done by ferry pilots&lt;/a&gt;. There are also &lt;a href=&quot;http://www.worldairops.com/flights.html&quot; rel=&quot;noreferrer&quot;&gt;some companies&lt;/a&gt; that perform these services for small airlines etc.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A ferry flight usually refers to the positioning of aircraft for maintenance, repair etc. This is done by the pilots of the airlines usually, with a special permit (i.e. the aircraft is not airworthy, but is flyable). As noted before, this can also be contracted out.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;For military aircraft, it is done by the service pilots.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-19T17:05:24.030" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22166" PostTypeId="1" AcceptedAnswerId="22170" CreationDate="2015-10-19T17:26:29.367" Score="4" ViewCount="377" Body="&lt;p&gt;Six weeks ago, roughly, a &lt;em&gt;Corsair&lt;/em&gt; charter flight landed at Lamezia Terme International Airport (SUF), in Southern Italy. It was a Boeing 747-422, registration F-HSEA. It carried 500 tourists from Liege Airport (LGG), Belgium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question&lt;/strong&gt;: when a flight like this is headed to an airport which is not an usual landing spot for wide-bodies, how does the ATC figure out a wide-body is coming? Do they figure this out by just communicating with the pilots when airborne or do they receive an official note beforehand?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cyhtp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyhtp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="1696" LastEditDate="2015-10-19T17:49:41.647" LastActivityDate="2015-10-19T20:47:28.423" Title="Does ATC handle non-regular widebody flights differently?" Tags="&lt;air-traffic-control&gt;&lt;boeing-747&gt;&lt;dispatch&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22167" PostTypeId="2" ParentId="22164" CreationDate="2015-10-19T17:28:57.123" Score="2" Body="&lt;p&gt;I'm not sure if 'most' airports have this design. I've seen both cases (i.e. departures below arrivals and the other way around). Atleast for small airports, a few reasons come to mind for having departures above arrivals:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If arrivals is on ground floor, the baggage can come easily from the aircraft. This reduces complexity, especially in small airports.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Most of the aircraft are boarded using jet bridge- makes sense if they are boarded from first floor (or above); of course, jet bridges can also be used for disembarking, so this is questionable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The upper floor offers a good view to enjoy while shopping or eating. This maybe the reason as more time is spent in departure. Also, if the arrival is in ground floor, one can simply 'walk out' as no checks are there (international flights are a different case).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;None of these arguments are convincing, I guess.  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-19T17:28:57.123" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22168" PostTypeId="2" ParentId="22086" CreationDate="2015-10-19T18:06:15.697" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.ogimet.com/metars.phtml.en&quot; rel=&quot;nofollow noreferrer&quot;&gt;OgiMet&lt;/a&gt; &lt;code&gt;Professional information about meteorological conditions in the world&lt;/code&gt; is such a site that offers 30-day history for METARs/SPECIs and TAFs reports.&lt;/p&gt;&#xA;&lt;p&gt;The coverage is said to be worldwide. Here is a glance at the query interface:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oMflc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oMflc.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The site states these conditions of use for the reports:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;About all the codified met. reports (SYNOPS, METAR ...), the copyright&#xA;are from every country or source institution. To use them,&#xA;read &lt;a href=&quot;http://www.nws.noaa.gov/im/wmocovr.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;WMO resolution 40&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(essentially it says it's free for use.)&lt;/p&gt;&#xA;&lt;p&gt;The site accepts requests for up to 31 days at once.&lt;/p&gt;&#xA;&lt;p&gt;Example: METARs for month of September 2020 for &lt;a href=&quot;http://www.ogimet.com/display_metars2.php?lang=en&amp;amp;lugar=lfpo&amp;amp;tipo=ALL&amp;amp;ord=DIR&amp;amp;nil=SI&amp;amp;fmt=html&amp;amp;ano=2020&amp;amp;mes=09&amp;amp;day=01&amp;amp;hora=00&amp;amp;anof=2020&amp;amp;mesf=09&amp;amp;dayf=31&amp;amp;horaf=18&amp;amp;minf=59&amp;amp;send=send&quot; rel=&quot;nofollow noreferrer&quot;&gt;Orly / LFPO&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o1FeI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o1FeI.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-12-04T18:22:30.333" LastActivityDate="2020-12-04T18:22:30.333" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="22169" PostTypeId="1" CreationDate="2015-10-19T18:30:13.840" Score="2" ViewCount="330" Body="&lt;p&gt;As a non-A&amp;amp;P, am I allowed to fabricate and install hydraulic fluid lines as part of preventive maintenance on an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="11750" LastEditorUserId="62" LastEditDate="2015-10-19T21:20:43.930" LastActivityDate="2015-10-20T14:51:38.233" Title="Can a non-A&amp;P fabricate and install his own hydraulic lines?" Tags="&lt;general-aviation&gt;&lt;aircraft-maintenance&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22170" PostTypeId="2" ParentId="22166" CreationDate="2015-10-19T18:52:57.723" Score="9" Body="&lt;h3&gt;No, ATC does not handle these flights differently from regularly scheduled ops&lt;/h3&gt;&#xA;&lt;p&gt;ATC isn't concerned with why an airplane wants to go to an airport or whether they regularly operate there or even if there are ground services available for them at the destination.&lt;/p&gt;&#xA;&lt;p&gt;Whether the flight is regularly scheduled or not may fall under different regulations but ATC services do not vary.  The charter flight will be operated under instrument flight rules (IFR) and will have a flight plan filed with ATC prior to departure.  The controllers at the departure airport will receive information about the flight prior to that planes departure and will service the flight to its filed destination.  This works exactly the same way as normal scheduled service by that same (or any other) airline.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-19T20:47:28.423" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22171" PostTypeId="2" ParentId="22166" CreationDate="2015-10-19T20:17:20.407" Score="3" Body="&lt;p&gt;Flight plan aside (if you are going VFR) here in the US you identify your make/type when hailing the tower. For example  if you enter the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspace_class_(United_States)#Class_D&quot; rel=&quot;nofollow&quot;&gt;Delta Airspace&lt;/a&gt; around an airport your hail may be &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Northeast tower; Piper N347G4 At 3000 with information Mike requesting clearance to land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this case the tower will know you are a piper and may (if available) assign you to a smaller runway if they have say two parallel runways of differing lengths or ask if &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Land-and-Hold-Short-Operations-LAHSO&quot; rel=&quot;nofollow&quot;&gt;Land And Hold Short&lt;/a&gt; is possible for you. I have even had the tower ask what type I was (&quot;Arrow&quot;, &quot;Cherokee&quot;, &quot;Warrior&quot; etc.). This will allow the tower to sequence traffic with any special needs as may be required. If a large jumbo is coming in followed by a small Cherokee 140 they may have the Cherokee extend its downwind to help avoid wake turbulence (they will also warn the Cherokee of possible wake turbulence).      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-19T20:36:21.903" LastActivityDate="2015-10-19T20:36:21.903" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22172" PostTypeId="2" ParentId="22169" CreationDate="2015-10-20T01:27:20.743" Score="3" Body="&lt;p&gt;Generally speaking someone who does not hold a mechanic's certificate may not fabricate their own hardlines or hoses, nor may they replace hardlines. This work must be done by someone holding the appropriate Airframe and/or Powerplant mechanic rating.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An owner/operator with a private pilot certificate may install prefabricated flexible fluid carrying hoses (&lt;em&gt;with the specific exception of hydraulic hoses&lt;/em&gt;) as preventive maintenance,as allowed under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=ap14.1.43_117.a&amp;amp;rgn=div9&quot; rel=&quot;nofollow&quot;&gt;FAR 43 Appendix A&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are three notable exceptions to the above general statements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;An owner of a Special Light Sport aircraft may acquire a repairman certificate, enabling them to perform this kind of work on their aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The builder of an Experimental Amateur-Built aircraft (&quot;homebuilt&quot;) may perform this work on aircraft they have built, as FAR 43 does not govern maintenance on aircraft with an Experimental airworthiness certificate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If working under the supervision of an A&amp;amp;P mechanic you are authorized to perform any work your supervisor is authorized for (per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=se14.1.43_13&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;FAR 43.3 (d)&lt;/a&gt;, and subject to some specific requirements).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-20T01:27:20.743" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22173" PostTypeId="2" ParentId="22164" CreationDate="2015-10-20T01:38:09.677" Score="0" Body="&lt;p&gt;It has something to do about terminal design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equipements, handlings and airport services has to operate at ground level. That's where departures and arrivals at an upper level came from. There is not always the necessary room to lay everything at ground level. Though, thousand of smaller airports are not multilevel, mainly because they don't have that much passengers and cargo movements to justify the amount of investment to do for such extensions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why, when cost is not an issue, departures are usually above arrivals ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cost is always an issue. Pragmatic and practical reasons :&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elevators, speedwalks, escalators... works with electricity and must be maintained. The more you add those in the design, the more it costs. You can avoid them when you were able, by default, to bring most things at an higher level, and let them move with the help of gravity, or at least, reduce energy consumption by limiting the cases where something or someone has to go at an upper level. This doesn't explain why departures are usually above arrivals, but is the start of some explanations below...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;as I said, luggages can be moved with the help of gravity. Let's assume departures are at ground level and arrival upstairs. Passengers's luggages go straight through checkings upon departure, then are loaded in the aircraft. Arriving luggages are unloaded from the plane, then goes upstair (move up). If it was the other way around, departing passengers's luggages goes downstair (move down). At this stage, the only difference is the move up/move down. When it comes about cost, it's better to move down only.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;But, upon departure, you not only have to check-in. There are control checks, and in case of international flights, extra checks. That is available space concern. Plus, you add boarding area with benches/chairs, duty free, lounges, and other goodies that consumes space. Obviously, you ought to have a lot of available space for your terminal to have both departure flow and equipement services at the same level. That's why, on some terminals, arrivals are on the same level as those equipement services as they require less formalities than departures, and can be designed to fit on the same level as services. =&gt; departures on the upper level.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Parking lots. By design, it cost less to set parking lots at ground level. It's much more expensive to place them underground. While raising them above ground can be much more or less expensive than underground ones depending on the circumstances, it's usually assumed it would cost much more. Most frequent practice is to bring departing passengers in front of the checkings (few steps to do) then park the car. Reciprocally, arriving passengers has to bring their luggage on their own to the parking lot, as it's uncommon to let hundreds of car peacefully wait in front of arrivals. If most parkings lots are at ground level or underground because of design cost, it's more practical to align arrivals with parking lots, or at least, narrow the difference in levels, both reducing elevators or alike usage/congestion, and amount of effort required from the passengers to reach their vehicle. (also note that on some airports, you can't bring luggage trolleys outside the terminal, meaning, you have to pull your 40lbs bag all the way to the car)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's better to wait in a roomy area than a narrow one. Think of the difference between waiting for boarding upon departure, and waiting for your luggage upon arrival. Even if it's usually wrong, it's assumed that you spend more time waiting for boarding upon departure, than waiting for your luggage upon arrival :P Well; in fact, to help you stay in a good mood and be open to spend some $$, departure areas are usually rooooooomy and beautiful ! You can only take advantage of that on the uppermost floor. People don't buy that much things upon arrival. They just want to have a rest, or get on time at their meeting or connection.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On a passenger's point of view, what matters is the distance one has to walk with that 40 lbs bag (even without) than anything else, no matter it's departure or arrival. Stairs are poor designs and not practical for trolleys. Elevators are known to be prone for traffic jams. The departure above arrivals is the design that best suits this requirement, and doesn't cost too much.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastActivityDate="2015-10-20T01:38:09.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22174" PostTypeId="2" ParentId="14596" CreationDate="2015-10-20T02:46:05.113" Score="1" Body="&lt;p&gt;Weather Underground is a great site, although finding the specific link for archived METAR reports is more difficult than it should be. The following link is an example that gives all METAR reports for a given airport on a given day; you can either use the fields given on the page to find other dates &amp;amp; other stations, or you could edit the URL itself to find what you want (and perhaps even automate that into a screen-scraping app):&#xA;&lt;a href=&quot;http://www.wunderground.com/history/airport/KJFK/2015/10/12/DailyHistory.html?req_city=Kennedy%20International&amp;amp;req_state=NY&amp;amp;req_statename=New%20York&amp;amp;reqdb.zip=11499&amp;amp;reqdb.magic=4&amp;amp;reqdb.wmo=99999&amp;amp;theprefset=SHOWMETAR&amp;amp;theprefvalue=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weather Underground Link&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also get the same data in a CSV file with &lt;a href=&quot;http://www.wunderground.com/history/airport/KJFK/2015/10/12/DailyHistory.html?req_city=Kennedy%20International&amp;amp;req_state=NY&amp;amp;req_statename=New%20York&amp;amp;reqdb.zip=11499&amp;amp;reqdb.magic=4&amp;amp;reqdb.wmo=99999&amp;amp;theprefset=SHOWMETAR&amp;amp;theprefvalue=1&amp;amp;MR=1&amp;amp;format=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;a separate link&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't mind doing a little bit of coding, you can also subscribe to their API, which allows you to get historical data with some fairly straightforward calls to their API.  The &quot;developer&quot; subscription is free but limited in how many calls you can make; more expensive subscriptions allow more calls.  The following link is &lt;a href=&quot;http://www.wunderground.com/weather/api/&quot; rel=&quot;nofollow noreferrer&quot;&gt;where you can start learning about their API.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;((This answer is as much an answer to &lt;a href=&quot;https://aviation.stackexchange.com/questions/22086/where-can-i-get-a-history-of-metars&quot;&gt;this question&lt;/a&gt;, which is now closed and marked as a duplicate of this one.  It is a slightly different question, and this answer is really more aimed at that question, but it addresses this question as well.))&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-10-20T02:46:05.113" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22175" PostTypeId="1" AcceptedAnswerId="22178" CreationDate="2015-10-20T03:28:57.280" Score="4" ViewCount="2966" Body="&lt;p&gt;I'm considering flying in a Spanish-speaking country and would like to have a passing familiarity with how to communicate with ATC in Spanish. Is there an ATC English-to-Spanish dictionary?&lt;/p&gt;&#xA;" OwnerUserId="2124" LastEditorUserId="2124" LastEditDate="2015-10-20T04:49:53.377" LastActivityDate="2018-05-12T16:02:21.657" Title="Where can I get an list of ATC phraseology terms in Spanish?" Tags="&lt;phraseology&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22176" PostTypeId="2" ParentId="22175" CreationDate="2015-10-20T03:52:50.610" Score="0" Body="&lt;p&gt;ICAO's official language is English, and they have introduced a &lt;a href=&quot;http://www.icao.int/safety/lpr/Pages/Language-Proficiency-Requirements.aspx&quot; rel=&quot;nofollow&quot;&gt;Language Proficiency Requirement&lt;/a&gt; aimed at raising proficiency for pilots and Air Traffic Controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Licensing for both ATC and Pilot licence holders has a requirement for proficiency at ICAO Level 4 or above&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO in Spanish is, therefore, something of a contradiction in terms. You should be able to get by just fine in English, but if you actually need to speak Spanish then you're probably not going to hear much ICAO phraseology.&lt;/p&gt;&#xA;" OwnerDisplayName="user11892" LastEditorDisplayName="user11892" LastEditDate="2015-10-20T05:12:10.290" LastActivityDate="2015-10-20T05:12:10.290" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22177" PostTypeId="2" ParentId="22126" CreationDate="2015-10-20T06:00:48.370" Score="8" Body="&lt;p&gt;The TPE331 in all of its flavors is susceptible to &quot;shaft bow,&quot; a condition in which the shaft connecting the compressors and turbines actually bends enough to seize the engine.  Even a tiny amount of bow will seize an engine.  Pilots of planes with the TPE331 (like the Conquest II, Merlins/Metroliner, MU2, etc) are trained to spin the engine through to remove residual heat from the engine core.  Spinning the prop through a few rotation causes the compressor/turbine sections to spin, expelling the heat (...or so pilots are taught!).  With a gear ratio of approximately 23:1, spinning the propeller all the way through once spins the core 23 times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The primary concern is &lt;strong&gt;not&lt;/strong&gt; heat removal.  No amount of manual spinning will &quot;cool&quot; the engine after it has just shut down!  It's really, &lt;em&gt;really&lt;/em&gt; hot inside of a freshly run engine and to think a few rotations of a propeller can exhaust that heat is silly.  Also, as the moment the engine is shut off, it spins freely for hundreds of rotations until it comes to a stop.  That free spinning as the engine winds down is sucking in more cool air than a pilot could possibly move through the engine manually!  The reason pilots are told to spin the prop (whether they know it or not) is to simply reorient the shaft so that it doesn't start to sag.  In reality, after all of that free spinning at shutdown, the propeller only needs to be moved a few blade widths to prevent shaft bow.  At a 23:1 gear ratio, rotating the prop a mere 7.8 degrees reorients the turbine shaft 180 degrees. That measly 7.8 degrees is what &lt;em&gt;really&lt;/em&gt; prevents shaft bow!  Operators of TPE331 equipped plane train their pilots to spin props many times just to make sure that the pilots actually move the prop enough to reorient the shaft.  Adjusting the prop 7.8 degrees or spinning it through 1000 times won't hurt the engine...only &lt;strong&gt;not&lt;/strong&gt; rotating the shaft will cause damage...over time...maybe...if you're really unlucky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Realistically, a pilot exiting a TPE331 equipped aircraft need only give the prop a playful nudge in the normal direction of rotation to prevent shaft bow.  Spinning though X-number of times won't hurt anything, but it's not necessary either.  Also, no need to go out 30 minutes later for another spin session.  These engines aren't made of glass...they just require a moment of attention after they've been run.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A certain company I worked for wanted me to spin the prop through 30 blades after each shutdown.  That procedure did not change between the 3 and 4 blade props...so, exactly &lt;em&gt;why&lt;/em&gt; were 30 blades chosen? Never got an answer to that!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TPE331 is a wonderful engine.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="14897" LastEditDate="2017-09-21T09:27:56.543" LastActivityDate="2017-09-21T09:27:56.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22178" PostTypeId="2" ParentId="22175" CreationDate="2015-10-20T06:31:48.913" Score="5" Body="&lt;p&gt;ICAO has defined in their Annexes that English is only one of the available langauges to ICAO and that ATS should either use the language specified in the country's AIP or use English.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.2.9    Language proficiency   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1.2.9.1    Aeroplane, airship, helicopter and powered-lift pilots, air traffic controllers and aeronautical station operators &#xA;  shall demonstrate the ability to speak and understand the language used for radiotelephony communications to the level &#xA;  specified in the language proficiency requirements in Appendix 1. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Note 2.— The provisions of 1.2.9 refer to Annex 10, Volume II, Chapter 5, whereby the language used for radiotelephony &#xA;  communications may be the language normally used by the station on the ground or English. In practice, therefore, there will &#xA;  be situations whereby flight crew members will only need to speak the language normally used by the station on the ground. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Personally, additional to my proficiency level in English, I also hold a Level 6 language proficiency German in my pilot's license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a screenshot of the Aerodrome Description for LEBL/Barcelona, taken from Spain's AIP. You see that ES/EN is listed as available languages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7Ryxp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Ryxp.png&quot; alt=&quot;AIP Spain LEBL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking for Spanish Phraseology, you can find it with &lt;a href=&quot;http://ais.anac.gov.ar/descarga/doc-52b1ec530a629&quot; rel=&quot;nofollow noreferrer&quot;&gt;Argentina's Administracion Nacional de Aviacion Civil&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-10-20T06:31:48.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22180" PostTypeId="1" AcceptedAnswerId="22184" CreationDate="2015-10-20T07:54:55.453" Score="1" ViewCount="824" Body="&lt;p&gt;How can the time for daily maintenance or A Check be calculated for different aircraft types?&#xA;&lt;br&gt;&#xA;Is there any exact formulation depending on the aircraft specifications?&#xA;&lt;br&gt; P.S.,I'm very new to the aviation field.&lt;/p&gt;&#xA;" OwnerUserId="11896" LastEditorUserId="1696" LastEditDate="2015-10-20T14:29:50.717" LastActivityDate="2015-12-15T23:48:55.703" Title="How is the amount of time for an A check or daily maintenance determined?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22181" PostTypeId="1" AcceptedAnswerId="22197" CreationDate="2015-10-20T09:25:39.853" Score="10" ViewCount="1055" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/22156/524&quot;&gt;This answer&lt;/a&gt; explains how pilots when switching code on transponder should either carefully avoid temporarily squawking one of the emergency codes, or should temporarily put the transponder in stand-by.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radios (both comm and nav) usually have an active frequency and a stand-by frequency and the pilot selects the stand-by frequency and then activates it with a button, which avoids temporarily selecting different frequency and limits the time when the radio is not receiving.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why don't transponders have similar mechanism? It seems it would be much more useful for them than it is for the radio.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-10-20T17:32:21.887" Title="Why don't transponders have active and stand-by value like radios?" Tags="&lt;flight-instruments&gt;&lt;radio&gt;&lt;transponder&gt;" AnswerCount="3" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22182" PostTypeId="2" ParentId="22181" CreationDate="2015-10-20T09:36:47.820" Score="11" Body="&lt;p&gt;For navigation and communication radios the feature of having a second readout that can be pre-set to the next frequency is useful since the next frequency is usually known in advance. Your next transponder code is a somewhat random number and the moment that you will get it is not as predictable as a frequency change. Therefore there is no need for a pre-set / standby squawk code in a transponder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, in a communication radio, when you pre-set the wrong frequency and cannot establish communication after the switch over, a single button press will bring you back to the original frequency. This prevents prolonged communication loss. This is similar in navigation radios. &#xA;For a transponder such a feature has no value, you won't switch back to the previous squawk code. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem of inadvertently selecting a special code can be addressed by other means. For example a digital interface that requires confirmation of the selected code before it is activated. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-20T10:12:06.300" LastActivityDate="2015-10-20T10:12:06.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22183" PostTypeId="2" ParentId="22180" CreationDate="2015-10-20T09:41:10.137" Score="4" Body="&lt;p&gt;This answer is not specific for A-checks, but covers the whole maintenance effort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try Eddins-Earles, Mary: Factors, Formulas and Structures for Life Cycle Costing, Eddins-Earles, 89 Lee Drive, Concord MA 01742, USA, 1981&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a bit dated, but has a wealth of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another source would be Fabrycky, Wolter J.; Blanchard, Benjamin S.: Life-Cycle Cost and Economic Analysis, Prentice-Hall International. ISBN 0135383234.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the white volume (I think it is No 8) of Jan Roskam's collection is a good start. Roskam, Dr. Jan: Airplane Design, Roskam Aviation and Engineering Corporation, Ottawa, Kansas 66067, USA, 1990.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, this is not exact science, so exact times cannot be expected. With experience, each operator will be able to estimate how long things take, but you do these checks to find possible damage which needs to be taken care of. A lot depends on the training and experience of the maintenance crew. The best way to approach this is with statistics.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-10-20T09:41:10.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22184" PostTypeId="2" ParentId="22180" CreationDate="2015-10-20T10:46:28.467" Score="3" Body="&lt;p&gt;The time taken for the daily maintenance or 'A' checks (or any other checks for that matter) depends on a number of parameters like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft configuration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The experience and skill level of the aircrew.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The condition (or age) of the aircraft and its components.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Requirement of any special checks (whether manufacturer/regulator mandated or operator requirement)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Usually, the checks to be carried out during each schedule (hourly or calender based) are determined by the manufacturer (sometimes in co-ordination with the operator) and laid down. The time required is then calculated by actually timing the operations and adding correction factors or by statistical analysis over a period of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to note is that this is not exact and will vary based on a number of factors. For the same checks, different operators (and manufacturer) may allot different time periods. If two different checks (for e.g. airframe and the engine) are required to be carried out at the same time, the time required will differ.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-20T10:46:28.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22185" PostTypeId="2" ParentId="22181" CreationDate="2015-10-20T11:29:26.713" Score="-4" Body="&lt;p&gt;Transponders are more technologically conservative than radios and the old models have a lot of analog electronics in them. You could certainly add the electronics and additional buttons to have them do a switchover the way radios do, and I think newer models can, but the older models are more primitive, which is why you see those instructions to use standby.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-10-20T11:29:26.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22186" PostTypeId="1" AcceptedAnswerId="22192" CreationDate="2015-10-20T12:45:20.890" Score="1" ViewCount="322" Body="&lt;p&gt;The second hand airliner market is active. Some airlines prefer to sell their aircraft within 5 years of purchase, like Ryanair. On the other hand, some airlines prefer to use second hand planes.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What criteria are considered to evaluate second hand airliners for purchase?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How are the used airliners sold to another operator?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-10-21T06:53:18.867" LastActivityDate="2015-10-21T06:53:18.867" Title="How much is a used airliner worth?" Tags="&lt;airliner&gt;&lt;aircraft-purchase&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-10-20T16:32:37.137" ContentLicense="CC BY-SA 3.0" />
  <row Id="22187" PostTypeId="1" CreationDate="2015-10-20T12:46:03.870" Score="0" ViewCount="243" Body="&lt;p&gt;I've often flown short flights around the US on aircraft built by non-American companies whose range is less than is required to make a traditional Atlantic crossing.  The Airbus A319-100, for instance, &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/airports-and-aircraft/Aircraft/airbus-a319-100.html&quot; rel=&quot;nofollow&quot;&gt;has a range of 2,400 miles&lt;/a&gt; while the distance &lt;a href=&quot;https://www.google.com/webhp?sourceid=chrome-instant&amp;amp;ion=1&amp;amp;espv=2&amp;amp;ie=UTF-8#q=distance+from+heathrow+to+jfk&quot; rel=&quot;nofollow&quot;&gt;from London to NYC is 3,440 miles&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do manufacturers get their small planes across oceans?  Do they operate factories in on all continents? Do they fly via Iceland or Greenland?&lt;/p&gt;&#xA;" OwnerUserId="890" LastEditorUserId="19" LastEditDate="2015-10-20T12:59:17.903" LastActivityDate="2015-10-20T12:59:17.903" Title="How do small planes cross oceans?" Tags="&lt;aircraft-design&gt;&lt;aircraft-manufacturer&gt;&lt;transatlantic&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-10-20T13:05:31.110" ContentLicense="CC BY-SA 3.0" />
  <row Id="22188" PostTypeId="1" AcceptedAnswerId="22248" CreationDate="2015-10-20T13:07:26.057" Score="14" ViewCount="2127" Body="&lt;p&gt;It probably is common guesswork to think that in nowadays' World we all speak English no matter what our mother tongue is. This should be even more the case with Civil Aviation, where &lt;strong&gt;everything&lt;/strong&gt; is in English and the staff is hired also based on its linguistic capabilities, yet the question arises:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;How does the ATC deal with a crew who is not capable of a clear pronunciation? The opposite might also happen.&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What to do in such cases?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="11885" LastEditDate="2015-10-20T18:18:28.453" LastActivityDate="2015-10-21T14:50:35.407" Title="How does ATC deal with a crew who is not capable of a clear pronunciation?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;pilots&gt;&lt;crew&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22189" PostTypeId="2" ParentId="22188" CreationDate="2015-10-20T13:16:12.517" Score="16" Body="&lt;p&gt;There is special phraseology snippets that allow information to be transmitted over the frequency with more accuracy, slower, repeated or worded differently.&lt;/p&gt;&#xA;&lt;p&gt;ATC may also query other company traffic to relay information in another language or they might use the ACARS/CPDLC system to transmit a text message, should both parties be capable.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;SAY AGAIN&lt;/p&gt;&#xA;&lt;p&gt;„Repeat all, or the following part, of your last transmission“&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Source: AIP Germany GEN 3.4)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;WORDS TWICE&lt;/p&gt;&#xA;&lt;p&gt;„Request: Communication is difficult. Please send every word, or group of words, twice.&lt;br /&gt;&#xA;Information: Since communication is difficult, every word, or group of words, in this message&#xA;will be sent twice.“&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Source: AIP Germany GEN 3.4)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;SPEAK SLOWER&lt;/p&gt;&#xA;&lt;p&gt;„Reduce your rate of speech“&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Source: AIP Germany GEN 3.4)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-20T13:16:12.517" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22190" PostTypeId="1" CreationDate="2015-10-20T13:22:27.490" Score="3" ViewCount="892" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_Aerostar&quot; rel=&quot;nofollow&quot;&gt;Ted Smith Aerostar&lt;/a&gt; has a very interesting history. Wikipedia has a list of all the models that were built. There's a note there about an Aerostar 800, only one of which was ever built. Does anyone know where that 800 is today?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-20T14:45:18.410" Title="Where is the only Aerostar 800 ever built?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22191" PostTypeId="2" ParentId="22190" CreationDate="2015-10-20T14:34:59.420" Score="2" Body="&lt;p&gt;According to &lt;a href=&quot;http://aerostar-owners.com/ChristyModels.php&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; page the airframe was donated to Embry-Riddle Aeronautical University:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Superstar airframe was later used as the prototype Aerostar 800. The prototype 800 was the Superstar airframe with two more seats (due to a 32” extension of the cabin) and featured two 400-hp. Lycoming engines. The 800 was under development when Ted unexpectedly passed on in 1976. Piper continued development of the airplane as a replacement for their P Navajo but never certified it and eventually donated the airframe to &lt;strong&gt;Emery Riddle [sic] Aeronautical University&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the only reference I can find to the ultimate location of the Aerostar 800. &lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="62" LastEditDate="2015-10-20T14:45:18.410" LastActivityDate="2015-10-20T14:45:18.410" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22192" PostTypeId="2" ParentId="22186" CreationDate="2015-10-20T14:39:56.240" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;HOURS/CYCLES&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The single most important factor in the value of an aircraft (generally speaking) is hours. This will almost single handedly define what the plane is worth. When a plane is built all the parts on it have a life time. This is traced through a series of logs for the plane. When a part is at or approaching its life time it must either be rebuilt or replaced. If you are looking at a plane that has high hours/cycles chances are parts on it will need replacing soon. This is costly to the new buyer and will often reflect in a lower sale price. Here in the US commercial aircraft require more frequent inspections than general aviation planes. These inspections are not cheap and a plane that needs inspection when compared to a plane that just came out of inspection will be reflected in the price as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are of course other factors like wear and tear, corrosion (which can be very costly to fix) and interior condition but generally speaking when large planes change hands they are at least partially repainted with the new companies livery and the interiors are often redone. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For some airlines it may be advantageous to buy second hand planes if they are already flying that make/model. Lets say smallTimeAir flies almost exclusively 727-200's this means they have a nice store of parts for that plane and a crew well experienced in fixing them. It will be easier for them to add another 727-200 to the fleet than say an A320 for which they will need new mechanics and parts they don't have. This makes some used airframes desirable to some people.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-20T14:39:56.240" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22195" PostTypeId="1" AcceptedAnswerId="22196" CreationDate="2015-10-20T16:18:39.033" Score="4" ViewCount="235" Body="&lt;p&gt;Yesterday I was watching a show about &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Mayday_episodes&quot; rel=&quot;nofollow&quot;&gt;Air Crash Investigation&lt;/a&gt;, the &#xA;Air France flight 447 case involving an Airbus A330-200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was watching it with Spanish voice dubbing and the weird part is that the narrator said the plane...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;reached a final speed of 13,000 km/h&lt;/li&gt;&#xA;&lt;li&gt;started falling at 7,000 km/h&lt;/li&gt;&#xA;&lt;li&gt;crashed at 200 km/h&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only speed value that makes sense to me is the last one: 200 km/h. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guess is that something was missed in translation. What is usually the speed measure for aircraft in the US? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also thought about the 7,000 figure, and perhaps instead of speed in km/h it meant altitude in feet?&lt;/p&gt;&#xA;" OwnerUserId="11905" LastEditorUserId="19" LastEditDate="2017-02-06T09:25:36.200" LastActivityDate="2017-02-06T09:25:36.200" Title="What could these possibly incorrectly translated numbers for aircraft speed have been?" Tags="&lt;accidents&gt;&lt;af447-accident&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22196" PostTypeId="2" ParentId="22195" CreationDate="2015-10-20T17:06:31.750" Score="7" Body="&lt;p&gt;I think there is some information lost in translation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The speeds of 13000 kmph are associated with reentry vehicles. The aircraft won't have had time to accelerate to that speeds in the first place, even if there is no atmosphere. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The (forward) speed is usually measured in mph in US (to the best of my knowledge). The vertical speed is given usually in feet per minute. Note that the aircraft speed is usually given in knots (or its Mach number) by convention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the numbers you've quoted:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;7000&lt;/strong&gt; When the autopilot disconnected, the roll angle increased in two seconds from 0 to +8.4 degrees. In response, the Pilot Flying (PF) applied nose-up sidestick inputs, which the Investigation termed as &lt;em&gt;abrupt and excessive&lt;/em&gt;. As a result, the aircraft &lt;a href=&quot;http://www.popularmechanics.com/flight/a3115/what-really-happened-aboard-air-france-447-6611877/&quot;&gt;started to climb at 7000 ft/min&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;200&lt;/strong&gt; The &lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf&quot;&gt;(vertical) speed at impact&lt;/a&gt; was around 108 knots (10,912 ft/m), which is around 200 kmph.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;13000&lt;/strong&gt; I'm not sure about this one. The maximum altitude reached was less than this value (~11500m actually), so doesn't make sense. The only thing that is related to this number for that flight was the depth at which the wreckage was found- 3,980 metres or 13,060 ft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note: Most of the data is from the &lt;a href=&quot;http://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf&quot;&gt;Final accident report&lt;/a&gt; of Air France 447.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-20T17:06:31.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22197" PostTypeId="2" ParentId="22181" CreationDate="2015-10-20T17:32:21.887" Score="3" Body="&lt;p&gt;The transponders that have the problem of inadvertently selecting/transmitting &quot;incorrect&quot; (or emergency) codes are old-tech designs. Much like the old-tech radio designs there was no concept of &quot;standby frequency&quot; or &quot;code being entered&quot; - whatever was on the face of the instrument is what it's doing.&lt;br&gt;&#xA;Radios of the same vintage have the same interface (e.g. the KX-170b):&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rpPZd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rpPZd.jpg&quot; alt=&quot;This radio has no &amp;quot;standby&amp;quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual solution for the old-tech transponders is to think before you spin the knob. If you were squawking &lt;code&gt;7701&lt;/code&gt; and told to squawk VFR (1200 in the US or 7000 in most of Europe) you wouldn't turn the right-digit until you'd adjusted one of the other two so you wouldn't inadvertently squawk one of the emergency/alert codes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The radar system could still see you squawking the &quot;wrong&quot; code for one or two passes in this situation, but that's a self-resolving problem and it generally doesn't set off any alarms for ATC.) &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Modern (push-button entry) transponders do have an &quot;inactive&quot; squawk code in that then new code isn't transmitted until after you're done entering it.  Most also have a clear or one-touch VFR button in case you make an error entering the new code, so if ATC assigned you code &lt;code&gt;7001&lt;/code&gt; and you inadvertently punched &lt;code&gt;77&lt;/code&gt; in turbulence you don't need to keep entering a &quot;wrong&quot; code - just hit clear or VFR and try again.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-20T17:32:21.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22198" PostTypeId="1" AcceptedAnswerId="22209" CreationDate="2015-10-20T17:38:58.513" Score="10" ViewCount="52582" Body="&lt;p&gt;What advantage does a delta wing have over a swept wing with high AR for supersonic flight? And what disadvantage does a delta wing have over a swept wing with high AR for transonic flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde is made to cruise at supersonic speed--delta wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most commercial airliner--swept wing with high AR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would you design a supersonic airplane with the conventional airliner swept wings? On the other hand, would you design a transonic flight with delta wings?&lt;/p&gt;&#xA;" OwnerUserId="11656" LastEditorUserId="167" LastEditDate="2015-10-20T23:30:02.683" LastActivityDate="2018-06-28T10:34:26.480" Title="What are the advantages and disadvantages of a delta wing compared to a swept wing?" Tags="&lt;supersonic&gt;&lt;delta-wing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22199" PostTypeId="1" AcceptedAnswerId="22204" CreationDate="2015-10-20T18:17:39.160" Score="13" ViewCount="6610" Body="&lt;p&gt;In the attached area of the sectional chart we see restricted areas R-2101 and R-2102. Also covering that general area is a circular, thick, dashed magenta line. There's a notice there that I assume corresponds to it, but I wasn't familiar with this marking before I saw it. I glanced at the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt; but didn't see a reference. Anyone know what's happening here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/ZXab7Wp.png&quot; alt=&quot;sectional thick dashed lined&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-20T18:33:34.440" LastActivityDate="2015-10-22T11:09:36.450" Title="What is the thick, dashed, magenta line on a sectional chart?" Tags="&lt;aeronautical-charts&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22200" PostTypeId="2" ParentId="22199" CreationDate="2015-10-20T18:22:12.970" Score="0" Body="&lt;p&gt;Apparently there are &quot;National Security Areas&quot; which are marked with a dashed magenta line. Here is the description from the guide:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;National Security Areas indicated with a broken magenta line and&#xA;  Special Flight Rules Areas (SFRAs) indicated with the following&#xA;  symbol: , consist of airspace with defined vertical and lateral&#xA;  dimensions established at locations where there is a requirement for&#xA;  increased security and safety of ground facilities. Pilots should&#xA;  avoid flying through these depicted areas. When necessary, flight may&#xA;  be temporarily prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-10-20T18:32:42.120" LastActivityDate="2015-10-20T18:32:42.120" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22201" PostTypeId="1" AcceptedAnswerId="22207" CreationDate="2015-10-20T18:28:08.050" Score="11" ViewCount="5398" Body="&lt;p&gt;Cirrus touts the parachute as an added layer of safety. The parachute has obvious marketing value, but is the parachute's added safety a spin on the airframe's shortcomings? CAPS is not an option when buying a Cirrus, so what's the real reason for it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do the Cirrus SR-20 and SR-22 have the CAPS parachute? Can a Cirrus SR-20 or SR-22 be certified to fly without it?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2018-10-24T22:02:03.317" LastActivityDate="2018-10-25T02:59:59.570" Title="Why do the Cirrus SR-20 and SR-22 have the CAPS (parachute) system?" Tags="&lt;aircraft-design&gt;&lt;airframe-parachute&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="22202" PostTypeId="2" ParentId="22199" CreationDate="2015-10-20T18:31:15.207" Score="1" Body="&lt;p&gt;National Security Area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BVeQ0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BVeQ0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://flighttraining.aopa.org/pdfs/Intro_to_VFR_Chart_Symbols.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-10-20T18:31:15.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22203" PostTypeId="2" ParentId="22199" CreationDate="2015-10-20T18:31:28.747" Score="5" Body="&lt;p&gt;The thick dashed magenta line indicates a National Security Area.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;National Security Areas indicated with a broken magenta line national security area dashes and Special Flight Rules Areas (SFRAs) indicated with the following symbol: sfras , consist of airspace with defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots should avoid flying through these depicted areas. When necessary, flight may be temporarily prohibited.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer is in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt;, I just initially overlooked it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/4lDHhpn.png&quot; alt=&quot;aero chart user&amp;#39;s guide&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-20T18:31:28.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22204" PostTypeId="2" ParentId="22199" CreationDate="2015-10-20T18:33:27.293" Score="10" Body="&lt;p&gt;The Atlanta sectional &lt;a href=&quot;https://skyvector.com/?ll=33.621404670280945,-85.91033934962762&amp;amp;chart=301&amp;amp;zoom=2&quot; rel=&quot;noreferrer&quot;&gt;near KANB, KASN, and KPLR&lt;/a&gt; gives a hint:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;FOR REASONS OF NATIONAL SECURITY&lt;br /&gt;&#xA;PILOTS ARE REQUESTED TO AVOID FLIGHT&lt;br /&gt;&#xA;AT AND BELOW 5000’ AGL IN THIS AREA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It is called a &lt;a href=&quot;https://en.wikipedia.org/wiki/National_Security_Area&quot; rel=&quot;noreferrer&quot;&gt;National Security Area&lt;/a&gt;, which FAA’s training &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=42&amp;amp;sID=243&quot; rel=&quot;noreferrer&quot;&gt;ALC-42: Airspace, Special Use Airspace and TFRs&lt;/a&gt; describes as follows.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;National Security Areas&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;National Security Areas consist of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs may be temporarily prohibited by regulation under the provisions of &lt;a href=&quot;http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&amp;amp;sid=224f4caa299238689ebdbf7c741e5725&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.3.14.1.9.4&amp;amp;idno=14&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Section 99.7&lt;/a&gt;. Regulatory prohibitions will be issued by System Operations, System Operations Airspace and AIM Office, Airspace and Rules, and disseminated via NOTAM. Inquiries about NSAs Inquiries should be directed to Airspace and Rules.&lt;/p&gt;&#xA;&lt;p&gt;Example — National Security Area near Pueblo, Co. and request to avoid flight at and below 3000’ AGL.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/MOjif.jpg&quot; alt=&quot;National Security Area near Publeo, Colorado&quot; /&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Wikipedia gives a &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=42&amp;amp;sID=243&quot; rel=&quot;noreferrer&quot;&gt;brief description&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In United States aviation, a National Security Area is a designated airspace through which flight is discouraged for reasons of national security.&lt;/p&gt;&#xA;&lt;p&gt;Flight through NSAs is not prohibited and no special advance clearance or authorization need be obtained to enter them. However, pilots of aircraft are strongly encouraged to either stay clear of NSAs or obtain prior authorization to pass through them in order to reassure the controlling agency that no threat to national security exists.&lt;/p&gt;&#xA;&lt;p&gt;NSAs are a compromise between normal airspace and restricted or prohibited airspace. NSAs can be temporarily converted into restricted airspace by NOTAMs.&lt;/p&gt;&#xA;&lt;p&gt;On VFR sectional charts, NSAs are delimited by a heavy dashed magenta border and a special notation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-22T11:09:36.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22205" PostTypeId="1" AcceptedAnswerId="22208" CreationDate="2015-10-20T18:43:28.773" Score="8" ViewCount="3595" Body="&lt;p&gt;I recently bought a quadcopter and noticed every time I fly it there is this weird buzzing noise. I have heard this noise on other quadcopters around the same size as mine(4in by 4in). On an airliner turbofan engine you can sometimes hear this weird buzzing sound from the engines, which this sound is the n1 fan spinning faster than the speed of sound and resulting in this loud buzzing sound. So is my little quadcopter motors going supersonic or is it something else?&lt;a href=&quot;https://i.stack.imgur.com/aE7dK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aE7dK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;Source:(dynomodels.co.uk)&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="15311" LastEditDate="2017-11-17T18:00:00.313" LastActivityDate="2020-10-24T17:03:03.000" Title="Do quadcopter propellers break the sound barrier?" Tags="&lt;propeller&gt;&lt;noise&gt;&lt;model-aircraft&gt;&lt;quadcopter&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22206" PostTypeId="2" ParentId="22205" CreationDate="2015-10-20T18:55:01.277" Score="6" Body="&lt;p&gt;It's possible, but I would say unlikely. Supersonic propeller tips really mess with efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tip speed of many aircraft propellers is close to supersonic, and if not properly controlled can exceed the speed of sound, but most models don't get up that fast (and your blade tips don't have to be supersonic to be annoyingly loud).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a formula to figure out the speed of the blade tip. For your quadcopter multiply the blade RPM by the diameter (in inches), and multiply that by 0.00426&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ TipSpeed = RPM * Diameter * 0.00426 $&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The result is in Feet per Second.&lt;br&gt;&#xA;Anything over 1125 feet per second (343 meters per second) and your tips are supersonic.&lt;br&gt;&#xA;Anything over about 650  feet per second (200 meters per second) and the propeller is probably &lt;em&gt;really loud and annoying&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="11155" LastEditDate="2015-10-21T00:14:37.470" LastActivityDate="2015-10-21T00:14:37.470" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="22207" PostTypeId="2" ParentId="22201" CreationDate="2015-10-20T18:57:54.977" Score="15" Body="&lt;p&gt;Briefly, without the CAPS the aircraft could not be certified because it wouldn't meet the spin recovery requirements of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f21539a5b63fe55b45f85ff69772b792&amp;amp;mc=true&amp;amp;node=se14.1.23_1221&amp;amp;rgn=div8&quot;&gt;14 CFR 23.221&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read a lot of detail in Cirrus's own &lt;a href=&quot;http://cirrusaircraft.com/wp-content/uploads/2014/12/CAPS_Guide.pdf&quot;&gt;CAPS Guide&lt;/a&gt; but their design premise is that pilots are bad at recovering from spins, especially close to ground. Cirrus wanted to make a safer aircraft that could recover even if the pilot has no spin training at all, so they implemented two safety features: a &quot;cuffed wing design&quot; from NASA and the CAPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, the Cirrus would have to comply with 14 CFR 23.221(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Normal category airplanes&lt;/em&gt;. A single-engine, normal category airplane must be able to recover from a one-turn spin or a three-second spin,&#xA;  whichever takes longer, in not more than one additional turn after&#xA;  initiation of the first control action for recovery, or demonstrate&#xA;  compliance with the optional spin resistant requirements of this&#xA;  section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But, rather than comply directly by demonstrating the spin recovery, Cirrus asked the FAA to certify them based on the wing design and CAPS instead, as the CAPS Guide explains:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Given that Cirrus had demonstrated enhanced low speed handling&#xA;  characteristics that will help pilots to  avoid inadvertent spin entry&#xA;  and the presence of CAPS, the FAA granted Cirrus an Equivalent Level&#xA;  of  Safety (ELOS) for the spin recovery requirement of the&#xA;  certification regulations. This ELOS is accepted  by all civil&#xA;  aviation authorities that have certified the Cirrus SR20 and SR22&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The CAPS also has some other benefits, such as being easy to use for an untrained passenger (think pilot incapacitation). That might be an important &quot;why&quot; reason and selling point from a Marketing perspective but it isn't directly relevant for certification.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-10-20T18:57:54.977" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22208" PostTypeId="2" ParentId="22205" CreationDate="2015-10-20T19:17:14.387" Score="19" Body="&lt;p&gt;Almost certainly not. Given the comments specifying a $0.5$ inch radius (blade length,) that means the circumference of the path of the blade tips would then be &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$2 \pi \cdot 0.5 \, \text{inches} \approx 3.1415 \, \text{inches} \approx 0.2618 \,\text{feet}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To get to the speed of sound (which is approximately $1,126 \,\frac{\text{ft}}{\text{s}}$ at sea level,) that means you'd need to have the fan spinning at &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{1,126}{0.2618} \approx 4,301 \,\text{Hz} \approx 258,060 \,\text{rpm}$$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Needless to say, that's not happening unless you have one seriously expensive quadcopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The buzzing you hear is probably either the frequency at which the motor is spinning or, perhaps, the frequency of some oscillation of the fan blades. Most likely, though, it's just the frequency of the motor/fan.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2017-11-18T08:34:15.323" LastActivityDate="2017-11-18T08:34:15.323" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="22209" PostTypeId="2" ParentId="22198" CreationDate="2015-10-20T19:29:35.650" Score="11" Body="&lt;h2&gt;Benefits of a delta wing:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Due to the large root &lt;a href=&quot;https://aviation.stackexchange.com/questions/5005/what-is-the-chord-of-a-wing&quot;&gt;chord&lt;/a&gt;, a delta wing combines low relative wing thickness with a sufficiently thick wing spar for a lightweight structure. Since a low relative thickness keeps &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule/7454?s=12%7C0.1295#7454&quot;&gt;wave drag&lt;/a&gt; down (a drag component which occurs only in supersonic flow), this makes delta wings especially attractive for supersonic aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The large root chord gives the delta wing a high internal fuel volume even at a low relative thickness.&lt;/li&gt;&#xA;&lt;li&gt;The large root chord also provides it with a large surface area which helps to bring the minimum speed of the aircraft down.&lt;/li&gt;&#xA;&lt;li&gt;With sufficient leading edge sweep, a delta wing produces &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift/21071#21071&quot;&gt;vortex lift&lt;/a&gt;, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; can be turned into a means of increasing lift.&lt;/li&gt;&#xA;&lt;li&gt;A delta wing is naturally stable in pitch, therefore it does not require a separate tail surface.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Drawbacks of a delta wing:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The large wing area causes more viscous drag for the same amount of lift compared to a high &lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing/8797?s=11%7C0.1924#8797&quot;&gt;aspect ratio&lt;/a&gt; wing. Swept wings have a better lift-to-drag ratio (L/D) than delta wings.&lt;/li&gt;&#xA;&lt;li&gt;High-lift devices like fowler flaps are hard to integrate into delta wings. The higher relative thickness of regular airliner wings allows to integrate large flaps more easily, and the rearward location of the trailing edge of a delta wing will produce intolerable pitching moments if such flaps would be deflected.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Generally, the moderately swept high aspect ratio wings of subsonic airliners are ideal for flight at high subsonic Mach numbers. Delta wings are superior only in supersonic flight, and due to their good low speed characteristics they offer the best overall compromise for supersonic aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cdHRp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cdHRp.jpg&quot; alt=&quot;XB-70 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;North American XB-70 in flight, a classical delta wing design (picture &lt;a href=&quot;http://jpcolliat.free.fr/ProjetUS/images/xb70_02.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the canard wing, which has little sweep and a low aspect ratio: This kind of wing is ideal for supersonic flight, provided it has a low relative thickness. The main wing of the XB-70 is a delta wing to keep the take-off and landing speeds relatively low and offers the best compromise of low and high speed characteristics. Also, the wing tips could be deflected downwards to improve directional stability at supersonic speed and to improve L/D by using the waverider effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2apsV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2apsV.jpg&quot; alt=&quot;Boeing 787 wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NZu7d.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NZu7d.jpg&quot; alt=&quot;Airbus 350 wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wings of both the Boeing 787 (top, picture &lt;a href=&quot;http://www.wired.com/images_blogs/autopia/2011/03/boeing7478i07.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) and the Airbus A350 (bottom, picture &lt;a href=&quot;http://www.airlines-inform.com/upload/reviews_pictures/1000-upload-iblock-065-airbus-a350-first-flight_com.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) show their powerful high-lift devices in these pictures, which allow them to fly with less than half the wing area of a comparable delta wing aircraft. Also, the lower surface area translates into lower drag at high flight speed, and the higher possible wing span helps to reduce &lt;a href=&quot;https://aviation.stackexchange.com/questions/7528/why-is-the-use-of-tail-down-force-so-common/7529?s=28%7C0.1529#7529&quot;&gt;induced drag&lt;/a&gt;, making those wings far superior for efficient flight at high subsonic speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-20T19:53:31.567" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22211" PostTypeId="2" ParentId="606" CreationDate="2015-10-20T19:43:48.683" Score="3" Body="&lt;p&gt;Another factor the existing answers don't mention: if you are flying a two-seater glider alone, you might want to add ballast to correct your center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders are light, so a missing person can have a significant effect on the center of gravity. Two-seaters are optimized for flying with two people aboard. I've even seen lead ballast being used in the nose of a glider when a very thin and small trainee was flying with a heavy-set instructor in the back seat.&lt;/p&gt;&#xA;" OwnerUserId="1307" LastActivityDate="2015-10-20T19:43:48.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22213" PostTypeId="1" AcceptedAnswerId="22218" CreationDate="2015-10-20T21:04:42.287" Score="3" ViewCount="608" Body="&lt;p&gt;Apologies if this is not the proper forum for this question - &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's my situation: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dMIvO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dMIvO.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm trying to drop a payload via parachute with some accuracy.  I'm worried that in the above setup, the line will interfere with parachute deployment or - if not deployment - operation during flight (imagine wind pushing the chute into the line).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't tested this yet but plan to.  Does anyone know how the payload &amp;lt;&gt; anchor connection might be engineered to ensure full deployment throughout the descent? &lt;/p&gt;&#xA;" OwnerUserId="11908" LastEditorUserId="19" LastEditDate="2017-01-25T16:07:01.367" LastActivityDate="2017-01-25T16:07:01.367" Title="Is it possible to drop a payload via anchored parachute?" Tags="&lt;aerodynamics&gt;&lt;parachute&gt;&lt;payload&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22216" PostTypeId="2" ParentId="22198" CreationDate="2015-10-20T22:16:39.607" Score="-4" Body="&lt;p&gt;Delta wing advantages&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Can fly at high angles of attack, which that's why fighter jets use a delta wing to fly at very high angles of attack&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Provides good amount of drag for landing. On landing you need drag and that's the purpose of flaps is to increase drag and lift and you can make the flaps a little bit smaller&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Delta wing disadvantages&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lots of drag, which is caused by vortex lift that a delta wing uses instead of conventional lift. Instead of just suffering drag from a &lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_vortices&quot; rel=&quot;nofollow&quot;&gt;wing tip vortex&lt;/a&gt; you suffer even more with 2 extra vortices that form on a delta wing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With a swept wing you reduce drag by decreasing the lift. The problem with that type of wing at supersonic speeds is that you surfer from wave shock drag. Wave shock drag forms when air on top of the wing exceeds the speed of sound. Even at subsonic speeds that a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_787_Dreamliner&quot; rel=&quot;nofollow&quot;&gt;787&lt;/a&gt; travels at you suffer from wave shock drag. Air is moving so fast on top of the wing at subsonic speeds that it causes the air to break the sound barrier. If you try to fly a swept wing at supersonic speeds your aircraft is really going to suffer from &lt;a href=&quot;https://en.wikipedia.org/wiki/Wave_drag&quot; rel=&quot;nofollow&quot;&gt;wave shock drag&lt;/a&gt; and any faster speeds could result in the whole plane splitting apart and is very serious. A delta wing doesn't have a slope on top of the wing like a swept wing does so the air doesn't travel any faster than the aircraft does. The reason airliners use swept wings is to reduce the lift to reduce the amount of high pressure air that can rotate around the wingtip. The swept wings reduce wake vortex and wake vortex can actually decrease an aircrafts lift and you want as much lift as possible. The major companies that build airliners main focus is to decrease drag. With a supersonic aircraft your main focus is to reach supersonic speeds and aren't designed to reduce drag. So you wouldn't design a supersonic aircraft that has swept wings, but you would design it with delta wings.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-10-20T22:16:39.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22217" PostTypeId="2" ParentId="17010" CreationDate="2015-10-20T22:30:00.780" Score="2" Body="&lt;p&gt;Laws within the EU can vary, however I would &lt;strong&gt;&lt;em&gt;assume&lt;/em&gt;&lt;/strong&gt; it would be possible to carry on training in another country, however I am not sure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to know, would be to ask your flight school! :) &#xA;They may know, and could contact the school you want to move to and work out a deal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best of luck&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: In my country (Australia) it is possible to continue training overseas, even though we are not part of an EU style union.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT 2: As I stated, if you currently undertake flight training, your instructor would know better than any online message board.  &lt;/p&gt;&#xA;" OwnerUserId="11873" LastEditorUserId="11873" LastEditDate="2015-12-08T22:51:02.170" LastActivityDate="2015-12-08T22:51:02.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22218" PostTypeId="2" ParentId="22213" CreationDate="2015-10-20T22:50:03.590" Score="10" Body="&lt;p&gt;&lt;em&gt;I'm trying to drop a payload via parachute with some accuracy.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cut a hole in the middle of the parachute, make its edge smooth and install a pipe through the center of the box that contains the payload. Run the line through the pipe and parachute and let the payload fall from the balloon. I believe the trick will work for small parachutes able to deliver up to 10 kg to the ground.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-20T22:50:03.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22219" PostTypeId="2" ParentId="8917" CreationDate="2015-10-20T23:28:41.163" Score="2" Body="&lt;p&gt;Sure. As one more example to the excellent ones already posted, &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_9&quot; rel=&quot;nofollow&quot;&gt;British Airways Flight 9&lt;/a&gt; encountered a cloud of volcanic ash from an eruption in the Indonesian archipelago, resulting in the failure of all four of the 747's engines. The plane was able to glide far enough to exit the ash cloud and then get three of the four engines restarted in order to divert to Jakarta, where due to abrasion of the windscreen they were forced to make a full instrument landing at an airport that was not enforcing ILS protection protocols. There were no injuries reported on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the midst of the emergency, the captain, in typical British style, made the following announcement to the passengers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them going again. I trust you are not in too much distress.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-10-20T23:28:41.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22220" PostTypeId="2" ParentId="22201" CreationDate="2015-10-20T23:34:12.847" Score="0" Body="&lt;p&gt;My father has a fairly detailed &lt;a href=&quot;http://www.avweb.com/news/features/190126-1.html&quot; rel=&quot;nofollow&quot;&gt;answer&lt;/a&gt; to this question, based on experience.  His particular evaluation of the parachute:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Don’t fly a single engine plane that isn’t equipped with a parachute.&#xA;  Although the chances of actually encountering an emergency situation&#xA;  that is worthy of “pulling the chute” are probably small to&#xA;  infinitesimal over the course of any given pilot’s career, the penalty&#xA;  for not having a parachute is almost certain death. Each pilot has to&#xA;  establish and evaluate their own risk assessment criteria, but for me&#xA;  something that has a greater than 50% risk of death, even if only 1%&#xA;  of the time, is an unacceptable risk. That’s why I bought a Cirrus in&#xA;  the first place.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11912" LastEditorUserId="11912" LastEditDate="2015-10-21T02:27:28.597" LastActivityDate="2015-10-21T02:27:28.597" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22222" PostTypeId="1" AcceptedAnswerId="22225" CreationDate="2015-10-21T00:37:25.247" Score="3" ViewCount="2018" Body="&lt;p&gt;What are the various whine noises coming from the Boeing 787 cabin? Especially near the wing. I have seen tons of YouTube videos in which it has a noise during takeoff, or when flaps are being lowered or raised?&lt;/p&gt;&#xA;" OwnerUserId="11772" LastEditorUserId="19" LastEditDate="2016-11-21T14:47:11.253" LastActivityDate="2016-11-21T17:13:11.443" Title="What is the cause of the whiny noises in cabin of the Boeing 787?" Tags="&lt;airliner&gt;&lt;boeing-787&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22225" PostTypeId="2" ParentId="22222" CreationDate="2015-10-21T03:17:28.210" Score="2" Body="&lt;p&gt;Other people have complained about this too. Boeing should rename the type to the &quot;Whineliner&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The noise is caused by a hydraulic pump which is situated directly below the cabin. It mostly runs on takeoff and landing, but it can also run automatically at other times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dogs have been reported to need psychiatric treatment after being transported on a 787.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-10-21T03:17:28.210" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22226" PostTypeId="2" ParentId="15292" CreationDate="2015-10-21T04:05:10.063" Score="8" Body="&lt;p&gt;For gliders, the first BRS was used in the experimental flying wing SB-13. Since the pilot was placed in a cockpit much larger than the wing, the fairing in his back was mostly empty. This space was used to house three parachutes and a spring-activated small extraction chute. The system was first tested on a 1:3 scale model (picture below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/23JdX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/23JdX.jpg&quot; alt=&quot;Model test of the SB-13 parachute rescue system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Model test of the SB-13 parachute rescue system (own work)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, the full-size system was tested with the cockpit section alone. The mass of the wings was simulated by stacks of steel plates bolted to the sides of the fuselage. The picture below shows the test with three chutes; the small spot on the left is the lid of the parachute compartment falling away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/obKWV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/obKWV.jpg&quot; alt=&quot;SB-13 full scale drop test&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SB-13 full scale drop test in 1989 (own work). The fuselage was lifted aloft by a helicopter and then dropped. The added tail surfaces made sure it fell nose down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the last test someone (not me!) forgot to switch on the receiver in the fuselage, so the parachute was never released. The fuselage was completely destroyed and the steel plates dug themselves so deeply into the soft ground that they were never found. We stopped digging after less than a meter, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The parachutes can be activated over the full speed range, however, at high speed the deceleration is quite severe. The riser lines are woven and will stretch under load, so the peak acceleration can be reduced. This means that the lines can be used only once. After activation, new and unstretched lines need to be fitted to make the system airworthy again.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-21T14:03:48.040" LastActivityDate="2015-10-21T14:03:48.040" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22227" PostTypeId="1" AcceptedAnswerId="22967" CreationDate="2015-10-21T04:52:10.237" Score="5" ViewCount="466" Body="&lt;p&gt;To win the tender of &lt;a href=&quot;https://en.wikipedia.org/wiki/Future_Strategic_Tanker_Aircraft&quot; rel=&quot;nofollow&quot;&gt;RAF Future Strategic Tanker Aircraft&lt;/a&gt;, Boeing, BAE systems and British Airways formed &lt;strong&gt;Tanker Transport Services Consortium&lt;/strong&gt; to offer air-to-air refuelling to military jets, using converted aircraft based on the B767 passenger jet. BA would provide the aircraft, Boeing would provide the conversion technology, and BAE systems would perform the majority of the aircraft modifications. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Roughly speaking, how much does it cost and how much labour hour is needed to convert a B767 airliner to military aerial refueling and strategic transport aircraft? &lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="5517" LastEditDate="2017-10-05T14:41:04.863" LastActivityDate="2017-10-05T14:41:04.863" Title="What are the costs and labour hours for converting a B767 airliner to an aerial refueling aircraft?" Tags="&lt;military&gt;&lt;mid-air-refueling&gt;&lt;boeing-767&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22229" PostTypeId="1" CreationDate="2015-10-21T05:11:53.850" Score="46" ViewCount="20445" Body="&lt;p&gt;I've ready many, many times that propellers are &lt;strong&gt;not&lt;/strong&gt; efficient near the speed of sound because it's so hard to get a tip-speed above Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then I came across this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zgnVf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zgnVf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-95&quot; rel=&quot;noreferrer&quot;&gt;Tu-95 &quot;Bear&quot;&lt;/a&gt;, a propeller-driven bomber whose blade tips actually move faster than the speed of sound. &lt;strong&gt;This is the only propeller aircraft I've ever seen whose blade tips do this.&lt;/strong&gt; There were even reports that submarines' SONARs could hear it from a long way off because those supersonic blade tips were so noisy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the plane has a &lt;strong&gt;range of 15,000 km.&lt;/strong&gt; That's pretty good, on par with today's huge commercial airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how can propellers be very inefficient at supersonic speeds, yet something like this is buildable on propeller-power only?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; Here is the main point of my question: It seems that &quot;all my life&quot; I've been told, &quot;propellers are not efficient at supersonic tip-speeds, and this is what drove the industry to jet power.&quot; And yet here is this apparent counterexample, the Tu-95. So how is this possible? What am I missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16948/do-helicopter-rotor-tips-regularly-go-supersonic?rq=1&quot;&gt;Here&lt;/a&gt; is a somewhat related question asking if helicopter blades regularly go supersonic. This is another point I've heard many times: heli blades don't do that because that would make them very inefficient. I'm assuming the rotors are effectively governed by the same laws of efficiency as a propeller for a fixed wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; the B-52 was mentioned in comparison so here are some figures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{array}{|l|r|r|r|} \hline&#xA; \text{Model} &amp;amp; \text{Fuel capacity [L]} &amp;amp; \text{Loaded weight [kg]} &amp;amp; \text{Range [km]}\\ \hline&#xA;\text{B-52} &amp;amp; 181,610  &amp;amp; 120,000  &amp;amp; 16,230 \\ \hline&#xA;\text{Tu-95} &amp;amp; 95,000  &amp;amp; 171,000  &amp;amp; 15,000 \\ \hline&#xA;\end{array}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This to me says the Tu-95 is &lt;strong&gt;very much more efficient&lt;/strong&gt;, because it has significantly more weight and significantly less fuel capacity, yet has about the same range.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2020-06-10T18:35:07.033" Title="Why is the Tu-95 so efficient despite having propellers that spin faster than the speed of sound?" Tags="&lt;aircraft-design&gt;&lt;turboprop&gt;&lt;efficiency&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="22230" PostTypeId="1" AcceptedAnswerId="22245" CreationDate="2015-10-21T05:29:15.090" Score="-2" ViewCount="1797" Body="&lt;p&gt;Which commercial jet aircraft have the option to install ACT (Additional Center Tank)? I think A321 has this option but I am not sure which other commercial jets have this option or this can be done with almost any plane?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="679" LastEditDate="2015-10-21T06:33:44.243" LastActivityDate="2015-10-21T13:26:00.387" Title="Which commercial jet aircraft have the option to install ACT (Additional Center Tank)?" Tags="&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22231" PostTypeId="2" ParentId="22229" CreationDate="2015-10-21T06:44:25.640" Score="71" Body="&lt;p&gt;Yes, propellers have problems at high speed, but if done right, they still have an advantage over turbofans at speeds up to Mach 0.8. Look at the inner engine gondolas of the Tu-95: They are elongated and thicker aft of the trailing edge. This was done to stow the landing gear in them, but also to &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule/7454#7454&quot;&gt;area-rule&lt;/a&gt; the aircraft. The Tu-95 applies knowledge that was gained only in the early jet age. This, of course, also explains the swept wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, it uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Contra-rotating_propellers&quot; rel=&quot;nofollow noreferrer&quot;&gt;contra-rotating propellers&lt;/a&gt; which spin very slowly (just 750 RPM). By having two coaxial propellers spinning in opposite direction, the efficiency at high speed is improved. The first propeller pre-swirls the flow so the flow conditions on the second propeller are more favorable for thrust creation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tips of the fan blades of a modern turbofan also move at supersonic speed, so the supersonic propellers on the Tu-95 do not create a direct disadvantage. By keeping the relative thickness of the blade near the tip low, the drag increase can be kept at tolerable levels. But make no mistake: Supersonic flow adds wave drag, and especially around Mach 1 the &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430#57430&quot;&gt;zero-lift drag coefficient of everything which moves through air&lt;/a&gt; has a maximum. It would make the Tu-95 even more efficient if it would fly at a lower cruise speed where the propeller tips are still subsonic, but Tupolev wanted to push the design to the highest useable cruise Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you learned about propellers and jets is not wrong, but it is not a black and white world, either. Airliners use jet engines to fly at the highest cruise speed possible, but at the cost of higher fuel consumption. If they would restrict themselves to lower speeds, &lt;a href=&quot;https://aviation.stackexchange.com/questions/15375/d8-double-bubble-aircraft-by-nasa/15392#15392&quot;&gt;plenty of fuel could be saved&lt;/a&gt;. But too few people would book these flights, because on intercontinental routes they will take noticeably longer. Note that turboprops are still used in regional air traffic, and even the regional jets have lower flight speeds than the intercontinental jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the efficiencies of engine types:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Piston engines are the most fuel efficient aviation engines. Their drawback is a constant power output over speed, so that thrust is inverse to speed. This helps for acceleration at take-off, but limits maximum speed. A modern piston engine uses 240 g of fuel for providing 1 kW of power over one hour: 240 g/kW-h. Diesel engines use as little as 220 g/kW-h. This number is already true for the old &lt;a href=&quot;http://en.wikipedia.org/wiki/Junkers_Jumo_205&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jumo 205&lt;/a&gt;, among the first aviation diesel engines in operation 80 years ago.&lt;/li&gt;&#xA;&lt;li&gt;Turboprop engines are next, and their power increases a little over speed due to ram pressure (which will raise the internal pressure in the engine by approx. 30% at Mach 0.8). Their power-specific consumption is &lt;a href=&quot;http://www.srs.aero/wordpress/wp-content/uploads/2009/03/srs-tsd-002-rev-1-pw120a-sfc-analysis.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;about 300 g/kW-h&lt;/a&gt; but goes down with increasing size, so the biggest turboprops approach piston engine levels of efficiency.&lt;/li&gt;&#xA;&lt;li&gt;Jet engines are less efficient than both, but are better for flying fast and high. Their thrust drops even less with speed, so the better basis for expressing consumption is thrust, not power. The typical fuel consumption of a modern jet engine (&lt;a href=&quot;http://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE-90&lt;/a&gt;) is 30 grams of fuel per Newton of thrust over one hour (30 g/N-h) when run stationary, and twice that in cruise at Mach 0.85. Modern &lt;a href=&quot;http://en.wikipedia.org/wiki/Pratt_%26_Whitney_F119&quot; rel=&quot;nofollow noreferrer&quot;&gt;Military&lt;/a&gt; jet &lt;a href=&quot;http://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;nofollow noreferrer&quot;&gt;engines&lt;/a&gt; achieve 80 g/N-h at take-off and have roughly constant thrust and specific consumption over speed. Since most innovation happens on turbofans these days, the most modern turbofans again approach piston engine levels of efficiency, but if you compare the same technological standard, they are less efficient than their piston and turboprop contemporaries.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In all cases, thrust is created by accelerating a mass of air backwards. The general equation for propulsive efficiency &lt;span class=&quot;math-container&quot;&gt;$\eta$&lt;/span&gt; is &lt;span class=&quot;math-container&quot;&gt;$$\eta = \frac{v_{\infty}}{v_{\infty}+\frac{\Delta V}{2}},$$&lt;/span&gt; where &lt;span class=&quot;math-container&quot;&gt;$\Delta v$&lt;/span&gt; is the speed increase of the mass of air due to that acceleration. This formula shows that it is better to accelerate a big mass of air only a little than a smaller mass by a lot. Propellers do this and for that reason offer the best efficiency. Turboprops use less efficient, but lighter gas turbines for creating power, but retain the efficient propeller. Civilian turbofans try to increase the mass of air by increasing their &lt;a href=&quot;http://en.wikipedia.org/wiki/Bypass_ratio&quot; rel=&quot;nofollow noreferrer&quot;&gt;bypass ratio&lt;/a&gt;, and only the military is using the least efficient types with bypass ratios below 1, because they are the best choice at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see a plot of the thrust-specific fuel consumption in cruise condition of different engine types over their bypass ratio. The inverse relation is easily visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eiaFY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eiaFY.jpg&quot; alt=&quot;Plot of thrust specific fuel consumption over bypass ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plot of the thrust specific fuel consumption in lb of fuel per lb of thrust per hour of different engines over the logarithm of their bypass ratio (picture &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/fig3BPRTrends_web.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make a comparison between piston and turbofan engines possible, let's compare fuel consumption at take-off. The formula for static thrust of a propeller is &lt;span class=&quot;math-container&quot;&gt;$$T_0 = \sqrt[3]{P^2\cdot\eta_{Prop}^2\cdot\pi\cdot d_P^2\cdot\rho},$$&lt;/span&gt; where &lt;span class=&quot;math-container&quot;&gt;$P$&lt;/span&gt; is the shaft power, &lt;span class=&quot;math-container&quot;&gt;$d_p$&lt;/span&gt; the propeller diameter and &lt;span class=&quot;math-container&quot;&gt;$\rho$&lt;/span&gt; the air density. For our example, we use a four-bladed prop of 3.4 m diameter and an engine with 1111 kW power. Its static thrust is 10.727 kN when we assume standard atmospheric conditions and a prop efficiency of 85%. The fuel flow will be 266.6 kg per hour, and relative to thrust this is 24.8 g/N-h or just 80% of that of a modern turbofan. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if even the enthusiasts could guess &lt;a href=&quot;http://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot; rel=&quot;nofollow noreferrer&quot;&gt;what airplane I used&lt;/a&gt;, because I obfuscated it by using those unfamiliar metric units. I guess nobody will argue that it is not optimized for fast flight, so this comparison should also hold for the Tu-95, for which I have less data available.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here follows the requested expansion on propeller tip speeds. Thanks to the excellent comment by @JanHudec not much is left to say: The &lt;a href=&quot;http://www.airforce-technology.com/projects/tu95bear/&quot; rel=&quot;nofollow noreferrer&quot;&gt;propeller diameter is 5.6 m&lt;/a&gt; and their speed is 750 RPM, so the circumferential component is &lt;span class=&quot;math-container&quot;&gt;$5.6 \cdot \pi \cdot 750 / 60 = 220 m/s$&lt;/span&gt;. Add to this the cruise speed of Mach&amp;nbsp;0.67 (taken from &lt;a href=&quot;http://www.airforceworld.com/bomber/eng/tu95.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; &amp;mdash; others list quite incredible numbers) at altitude, where the speed of sound is 295&amp;nbsp;m/s. Mach&amp;nbsp;0.67 equates there to 197.65&amp;nbsp;m/s, and vector addition gives 295&amp;nbsp;m/s for the propeller tips, exactly Mach&amp;nbsp;1.0. This means that the propeller is subsonic over its whole span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the top speed is quite a bit higher. Thanks to the excellent work of &lt;a href=&quot;https://en.wikipedia.org/wiki/Ferdinand_Brandner&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ferdinand Brandner&lt;/a&gt; and his team back in the Fifties the &lt;a href=&quot;https://en.wikipedia.org/wiki/Kuznetsov_NK-12&quot; rel=&quot;nofollow noreferrer&quot;&gt;NK-12 engines&lt;/a&gt; developed already 12,000 horsepower back then, and their power output has since been raised to 14,795&amp;nbsp;HP. This allows a top speed of Mach 0.82, and now the tip speed comes out at 327&amp;nbsp;m/s or Mach&amp;nbsp;1.08 &amp;mdash; mildly supersonic. This means that the outer 30% of the propeller experience supersonic flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fail to find a source for the range figures you list in your question. Again I refer to &lt;a href=&quot;http://www.airforceworld.com/bomber/eng/tu95.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt;: It is 7,800 miles or 12,552&amp;nbsp;km at a cruise speed of 400&amp;nbsp;knots or 179&amp;nbsp;m/s which equals Mach&amp;nbsp;0.606 at altitude, resulting in Mach 0.96 for the propeller tips. Therefore, it seems the best range is reached with subsonic propeller tips.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-28T05:04:06.110" LastActivityDate="2020-04-28T05:04:06.110" CommentCount="16" ContentLicense="CC BY-SA 4.0" />
  <row Id="22232" PostTypeId="1" CreationDate="2015-10-21T07:23:00.783" Score="27" ViewCount="7957" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RtcQ5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RtcQ5.jpg&quot; alt=&quot;View of A-10 underside in flight&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;Sup&gt;Source: &lt;a href=&quot;https://flic.kr/p/9oVL1S&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flickr&lt;/a&gt; courtesy of: U.S. Air Forces Central Public Affairs, photo by Master Sgt. William Greer&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice at the side edges, the wing peels down and back around towards the fuselage. (The airplane is upside-down in this photo.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never noticed this before. Is this a wing-tip device producing more lift? If so, what kind is it? I would like to read more about it.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="5517" LastEditDate="2016-04-15T16:50:59.933" LastActivityDate="2016-04-15T16:50:59.933" Title="Is this a wing-tip device on the A-10 &quot;Warthog&quot;?" Tags="&lt;aircraft-design&gt;&lt;winglets&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22233" PostTypeId="2" ParentId="22232" CreationDate="2015-10-21T07:45:39.333" Score="11" Body="&lt;p&gt;It's called a drooped wingtip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general idea is to move the vortex away from the wing, reducing it's influence.&#xA;As with all the winglet variants, opinions vary about whether or not it generates more lift than other variants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lNLwh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lNLwh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/WingtipDevicesS04.pdf?q=wingtip&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more aircraft that employ this type of wingtip device:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8kfz4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8kfz4.jpg&quot; alt=&quot;Glider with drooped tips&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wingtip_device&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eM34e.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eM34e.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.pipertomahawk.com/N2517B.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-10-21T07:45:39.333" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22234" PostTypeId="1" CreationDate="2015-10-21T09:48:59.140" Score="2" ViewCount="745" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;EDIT&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Soon after I posted this, it was pointed out that a &lt;a href=&quot;https://aviation.stackexchange.com/questions/3300/why-havent-quadcopters-been-scaled-up-yet/3391#3391&quot;&gt;similar question&lt;/a&gt;&#xA;  exists. That other question answers most of mine. I shall leave this here as a stub. That way it provides a pointer to the other question and, importantly, my title contains all the keywords 'model', 'quadcopter','helicopter' and 'scale up' whereas the other question's title (Why haven't quadcopters been scaled up yet?) is less comprehensive and therefore less searchable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Model helicopters were on the market for many, many years before quadcopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Presumably most of the engineering bugs had been removed by then as well as control issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suddenly along comes the new kid on the block and it's all change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Related questions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Why are model quadcopters so popular in relation to model helicopters?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How come the same reasons don't apply to full-size helicopters and quadcopters? Why don't we see search and rescue quadcopters and personnel-carrying quadcopters?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9417" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-21T10:18:38.950" Title="Why is a model quadcopter 'better' than a helicopter? Why doesn't this scale up to the full-size versions?" Tags="&lt;helicopter&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-10-21T17:24:06.503" ContentLicense="CC BY-SA 3.0" />
  <row Id="22235" PostTypeId="2" ParentId="22234" CreationDate="2015-10-21T10:02:29.680" Score="5" Body="&lt;p&gt;Cheap &lt;a href=&quot;http://www.memsnet.org/mems/what_is.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;MEMS&lt;/a&gt; gyroscopes have been on the market only since maybe 10 years. Before you needed &lt;a href=&quot;https://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;nofollow noreferrer&quot;&gt;more bulky and expensive gyros&lt;/a&gt;. Also, cheap and powerful micro controllers which can process the sensor data quickly enough and can control the speeds of the four motors to stabilize the quadcopter have only been available recently. The third recent innovation was more gradual, but also the storage density of batteries was not available maybe 20 years ago. With modern &lt;a href=&quot;https://en.wikipedia.org/wiki/Lithium_polymer_battery&quot; rel=&quot;nofollow noreferrer&quot;&gt;LiPo batteries&lt;/a&gt; you can have flying times of several minutes where &lt;a href=&quot;https://en.wikipedia.org/wiki/Nickel%E2%80%93cadmium_battery&quot; rel=&quot;nofollow noreferrer&quot;&gt;NiCd batteries&lt;/a&gt; only gave you a fraction of that time for the same mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For your second question: The reason is similar to why birds have not been scaled up to carry humans, like horses do. &lt;a href=&quot;https://aviation.stackexchange.com/questions/3300/why-havent-quadcopters-been-scaled-up-yet&quot;&gt;This answer&lt;/a&gt; should give a good explanation. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-10-21T10:02:29.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22236" PostTypeId="2" ParentId="22232" CreationDate="2015-10-21T10:13:19.747" Score="25" Body="&lt;p&gt;The wingtip devices used in A-10 Warthogs are called drooped wingtips (also called Hoerner wingtips in some cases), which essentially increase the aspect ratio of the wing by forcing the vortices further out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3oj24.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3oj24.gif&quot; alt=&quot;Drooped wing tip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: zenithair.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few reasons for having this wingtip device:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The drooped wingtips act in a manner similar to the winglets and reduce the induced drag. As a result, the loiter capability of the aicraft, an important one for Close Air Support (CAS) aircraft, is improved. The A-X competition, that lead to the A-10 develpment, required the aircraft to have &lt;em&gt;Two hour mission loiter time at max mission radius with 9,500 lbs payload&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The drooped wingtip increases the local span loading near the wingtip, due to which the aileron response is improved, increasing the manuverability at low altitudes. The A-X competition required the aircraft to be &lt;em&gt;Highly maneuverable below 1,000 ft&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The drooped wingtips also improve the takeoff performance, an advantage as the aircraft is expected to be operated from short, forward fields. Infact, drooped wingtips are found in &lt;a href=&quot;http://www.stolairus.com/product/BEA001&quot; rel=&quot;noreferrer&quot;&gt;STOL kit of some aircraft, like DC-2 Beaver&lt;/a&gt;. One of the requiremens of the A-X competition was that the aircraft should have &lt;em&gt;4,000 ft takeoff distance&lt;/em&gt; at MTOW.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As can be seen, the drooped (down) wingtips wingtips serves these purposes. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There seems to be some confusion regarding the reason for these wingtip devices. One theory (@Peter Kämpf) is that they are there to protect the ailerons from ground contact. However, I think this is unlikely, given the ailerons, when extended, go well beyond the wingtips, as shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g65ae.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g65ae.jpg&quot; alt=&quot;Aileron extended&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: scienceforums.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dropped down wingtips do serve that purpose (sometimes) in gliders. However, there is no reason to believe that is the case here, considering the height above the ground and the aspect ratio. The drooped wingtips, on the other hand serve to hold the countermeasure system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ByXdX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ByXdX.jpg&quot; alt=&quot;CMDS wingtip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: rcgroups.net&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-21T17:04:08.150" LastActivityDate="2015-10-21T17:04:08.150" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22237" PostTypeId="1" AcceptedAnswerId="22238" CreationDate="2015-10-21T10:38:28.090" Score="6" ViewCount="1104" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4YeXo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4YeXo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone explain what is the teardrop-shaped item behind the cockpit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XlcSH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XlcSH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="946" LastEditDate="2016-02-20T01:05:23.503" LastActivityDate="2016-02-20T01:05:23.503" Title="What is the teardrop-shaped appendage on the T-6 Texan?" Tags="&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22238" PostTypeId="2" ParentId="22237" CreationDate="2015-10-21T11:10:35.550" Score="7" Body="&lt;p&gt;It is the RDF antenna 'bullet' (or teardrop, actually) fairing. This image shows the (loop) antenna itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CJMSh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CJMSh.jpg&quot; alt=&quot;RDF antenna&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: mission4today.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initailly, RDF antennas were circular loops mounted above or below the fuselage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xo1sf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xo1sf.jpg&quot; alt=&quot;Initial&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Earhart-electra_10.jpg#/media/File:Earhart-electra_10.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Earhart-electra 10&lt;/a&gt;&quot; by Originally uploaded by w:User:Logawi - Transferred from en.wikipedia, description page is/was here.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later loop antenna designs were enclosed in an aerodynamic, teardrop-shaped fairing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K5DA8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K5DA8.jpg&quot; alt=&quot;B 17 loop antenna&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airpages.ru&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-21T11:16:10.910" LastActivityDate="2015-10-21T11:16:10.910" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22239" PostTypeId="2" ParentId="22232" CreationDate="2015-10-21T11:13:53.297" Score="5" Body="&lt;p&gt;Oh boy, you guys are obsessed with that wingtip vortex, seemingly the source of all drag. No, the reason for this wingtip shape is &lt;strong&gt;much simpler&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's about the protection of the ailerons from ground contact &lt;strong&gt;at low level flight&lt;/strong&gt;. This is especially important for gliders with their central wheel, but also for aircraft which maneuver a lot at low altitude. They will benefit from something that takes the impact forces and keeps the control surface intact and working, especially when this surface will be deflected downwards at the time of ground contact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Honestly, this is the reason, not some esoteric vortex shifting.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-21T14:01:10.460" LastActivityDate="2015-10-21T14:01:10.460" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="22241" PostTypeId="1" CreationDate="2015-10-21T11:50:20.830" Score="1" ViewCount="621" Body="&lt;p&gt;I have tried many different ways to try to find where it is stored, but have had no luck.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2015-10-21T14:22:46.630" Title="Where is the first Boeing 747-8 ever built stored at today?" Tags="&lt;boeing-747&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22242" PostTypeId="1" AcceptedAnswerId="22249" CreationDate="2015-10-21T11:59:18.157" Score="3" ViewCount="390" Body="&lt;p&gt;I was recently flying my quadcopter and it started to go out of control. It was because I was flying it below a ceiling fan which acted as a mini downburst shoving the little quad to the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So have there ever been reports of a helicopter accidently flying into a downburst?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2015-10-24T13:41:03.020" LastActivityDate="2015-10-24T13:41:03.020" Title="Has there ever been a report of a helicopter flying into a downburst?" Tags="&lt;helicopter&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-29T14:31:38.007" ContentLicense="CC BY-SA 3.0" />
  <row Id="22243" PostTypeId="2" ParentId="22241" CreationDate="2015-10-21T12:03:33.990" Score="6" Body="&lt;p&gt;The first 747-8 built was not a protype, but a production unit. The first delivered aircraft in both the versions (747-8i Intercontinenal and 747-8F Freighter) are in service, the Passenger version with Lufthansa and the cargo version with Cargolux.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first 747-8 customer was Cargolux for the 747-8F version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first 747 ever built, 747 RA001 'City of Everett' is in Museum of Flight in Seattle.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-21T14:22:46.630" LastActivityDate="2015-10-21T14:22:46.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22244" PostTypeId="1" CreationDate="2015-10-21T12:39:05.070" Score="10" ViewCount="2980" Body="&lt;p&gt;In my company we have a problem that we cannot understand completely, because we  cannot find the answer.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If I don't have the runway in sight at the circle minimum (MDA) on an ILS&#xA;approach, I must immediately execute a missed approach or can I level off and maintain the circle minimum (MDA) and continue inbound until reach the MAPt by DME or timing block (don't have DME) and missed approach?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If a RVR is published in the chart, normally it is RVR at MAPt right? For ILS (precision approach) it is clear that MAP is at the DA. LOC (Non-precision approach) uses MDA at MAPt by DME or timing but for circling where is a MAPt? Use same Non-precision or use circle minimum (MDA) on glide?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If we fly ILS for circling, is it a precision or non precision approach? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11923" LastEditorUserId="19" LastEditDate="2015-10-21T13:03:32.327" LastActivityDate="2017-06-07T11:02:12.013" Title="Where is a missed approach point for circling while flying ILS?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22245" PostTypeId="2" ParentId="22230" CreationDate="2015-10-21T13:26:00.387" Score="1" Body="&lt;p&gt;In terms of a non permanent installation almost any aircraft can be plumbed to accept a &lt;a href=&quot;http://www.turtlepac.com/photo-gallery/aircraft-ferry-tanks.html&quot; rel=&quot;nofollow&quot;&gt;Ferry Tank(s)&lt;/a&gt; this is typically done for smaller aircraft to transport them over open water distances they can not otherwise cross. As far as I know this is not really done in commercial operations but you can add tanks.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviationweek.com/commercial-aviation/airbus-launches-long-range-a321neo-version&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; seems to confirm the center tank on the A321.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are asking about a tank that can be added and removed quickly I do not know of any but from a regulatory standpoint doing so would require separate weight and balances to be prepared for both cases.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-21T13:26:00.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22246" PostTypeId="2" ParentId="22229" CreationDate="2015-10-21T13:30:57.527" Score="2" Body="&lt;p&gt;This is not a Tu-95 specific answer. Keep in mind that a propeller produces force in the same manner as an airplane wing. Subsonic and supersonic wings both produce lift, though using very different design profiles. I would get a good, close look at the propeller to see how the tip area is designed. It may be diamond-shaped, like a supersonic airfoil, or it may be very flat, where the function is not lift, but to reduce vortex energy loss, like that of newer commercial aircraft. As long as the supersonic portion of the propeller does not have the profile of a subsonic airfoil, it will not produce the undesirable effects.&lt;/p&gt;&#xA;" OwnerUserId="11924" LastActivityDate="2015-10-21T13:30:57.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22247" PostTypeId="1" AcceptedAnswerId="22250" CreationDate="2015-10-21T13:54:21.287" Score="3" ViewCount="3047" Body="&lt;p&gt;I learned that on modern airliners, the Rudder input is given by the pedals located under the pilot's feet, and that got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;how do the pilots give the command to brake the plane in order to slow it down on ground (landing/taxing)?&lt;/li&gt;&#xA;&lt;li&gt;Is the parking brake and &quot;regular&quot; wheel brake part of the same system?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="1700" LastEditDate="2015-10-21T14:04:28.120" LastActivityDate="2015-10-21T14:21:33.617" Title="Where is the regular wheel brake input on modern airliners?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;braking&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22248" PostTypeId="2" ParentId="22188" CreationDate="2015-10-21T14:02:57.830" Score="5" Body="&lt;p&gt;From a legal standpoint English is not only the official language of aviation but you must be &quot;&lt;a href=&quot;https://www.faa.gov/licenses_certificates/airmen_certification/english_proficiency/&quot; rel=&quot;nofollow noreferrer&quot;&gt;English Proficient&lt;/a&gt;&quot; to legally fly at least here in the US. This is both an &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2008/inFO08012.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA and ICAO&lt;/a&gt; requirement these days. Although what happens when a repeat is needed has been covered in other answers it should be noted that accents should not stand in the way of communications and you may, depending on your case be required to have an &quot;English Proficient&quot; endorsement on your license. In reality there should never be a pronunciation issue (but we live in a far from perfect world)  Here is the full ICAO chart of grading, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GxtnK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GxtnK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.experimentalaircraft.info/alr/language-proficiency-endorsement.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flightsafety.org/aerosafety-world-magazine/december-2011-january-2012/language-gap&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is some interesting info&lt;/a&gt; on the dangers of language differences in aviation accidents. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the fact that some aircraft radios garble signals and don't help in transmitting marginally acceptable audio all while in a plane with near defining engine noise; that is a whole separate question... &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-21T14:50:35.407" LastActivityDate="2015-10-21T14:50:35.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22249" PostTypeId="2" ParentId="22242" CreationDate="2015-10-21T14:09:55.490" Score="13" Body="&lt;p&gt;Yes, it would be really amazing if it had never happened. Since &quot;reports&quot; are only required in the case of accidents, here are extracts from three NTSB summaries:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20130319X81018&amp;amp;key=1&quot;&gt;WPR13CA155&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During descent for an off-airport pinnacle landing, the helicopter&#xA;  encountered a downdraft about 75 to 100 feet above ground level (agl),&#xA;  and the pilot receiving instruction increased collective input. The&#xA;  flight instructor advised the pilot receiving instruction to be less&#xA;  aggressive using the collective as the flight continued to the landing&#xA;  area. As the helicopter descended through about 10 to 25 feet agl, it&#xA;  encountered a second downdraft, and the pilot receiving instruction&#xA;  increased collective again, which was followed by a decrease in rotor&#xA;  rpm.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20090914X80010&amp;amp;key=1&quot;&gt;ANC09LA098&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During the approach to the 5,657 foot level site, the pilot said he&#xA;  encountered a downdraft as the helicopter approached the site, and the&#xA;  helicopter descended below his anticipated approach path. He initiated&#xA;  a go-around, but the helicopter continued to descend, and landed hard,&#xA;  about 150 feet short and down slope of his intended touchdown point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20090928X05618&amp;amp;key=1&quot;&gt;WPR09CA470&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As he flew the helicopter out of the leeward side of the peak, he&#xA;  encountered a downdraft. He maneuvered the helicopter toward a wide&#xA;  open valley that descended about 5,000 feet below. The downdraft&#xA;  pushed the helicopter into the face of the mountain, despite the&#xA;  pilot's application of full collective and descending flight into the&#xA;  valley.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-10-21T14:09:55.490" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22250" PostTypeId="2" ParentId="22247" CreationDate="2015-10-21T14:19:02.907" Score="8" Body="&lt;p&gt;The same way it is done in small airplanes and older airlines -- toe brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rudder pedals translate forward and back to actuate the rudder and they pivot around the lateral axis to actuate the brake system.  Each pedal independently controls only the brakes on its side of the airplane (e.g both pilots left toe brake actuates the brakes on the left main gear).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes will often have an emergency or parking brake, which will be a lever somewhere that actuates the brake system.  This system, outside of emergencies is only used when the plane is not moving and you want it to remain that way.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger airplanes with also sometimes have autobrakes which provide a triggered automatic application of a certain level of braking.  This kind of system is used both to provide automatic maximum braking for a rejected takeoff (RTO) and some lesser automatic braking upon landing rollout.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To summarize, for taxi and ground movement the brake input is coming from the toe brakes.  When the aircraft is stopped, brake input will be transferred from the toe brakes to the parking brake.  When the plane lands, if it is so equipped and enabled, the autobrakes will begin brake application and the pilot will take over with the toe brakes and continue to use toe brakes for the taxi in.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-10-21T14:19:02.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22251" PostTypeId="2" ParentId="22247" CreationDate="2015-10-21T14:21:33.617" Score="3" Body="&lt;p&gt;The brake controls are located in the rudder pedals themselves. The manual braking is achieved by pressing the top part of the rudder pedals (so called toe-brakes). See this video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/-7ormVjGh5o?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Differential braking is achieved by pressing the rudder pedals on one side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The parking and 'regular' wheel brakes are usually part of the same system.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-21T14:21:33.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22253" PostTypeId="2" ParentId="22244" CreationDate="2015-10-21T15:43:45.303" Score="10" Body="&lt;p&gt;Circling approaches are non-precision, regardless of how you arrive at the MDA.  When circling you'll level off at the circling MDA and use the missed approach point depicted for the approach.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking at a Jeppesen approach plate there should be a level-off and 'M' depicted in the profile view.  If you are looking at government plates the level-off and MAP are not depicted in the profile view but are still specified elsewhere.  In any case, you'll fly the localizer to the MAP and then go missed.  You'll descend either via the GS or step down altitudes to the circling  MDA and stay there until either the MAP or you are able to further descend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RVR probably won't be listed for circling minimums (it isn't published for the chart as a whole) as they will generally be at least 1 mile or more.  Whether the visibility requirement is specified in feet (RVR) or miles, this is the visibility you need to descend out of the circling MDA.  You have the further restriction that you may not descend out of MDA until you are in a position to land.  The same familiar rules in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1175&quot; rel=&quot;noreferrer&quot;&gt;91.175&lt;/a&gt; still apply. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, fly the approach like you normally would but level off at the non-precision circling MDA and go missed at the non-precision MAP if you have no visual contact with the runway.  You do not go missed exactly upon reaching the MDA, just as you wouldn't if you were flying a VOR or LOC approach.  You go missed at the missed approach point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z4Vij.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z4Vij.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-10-21T20:21:03.990" LastActivityDate="2015-10-21T20:21:03.990" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22254" PostTypeId="2" ParentId="22213" CreationDate="2015-10-21T16:05:16.913" Score="3" Body="&lt;p&gt;If the hot air balloon is well anchored you can probably just use your original plan.  The winds aloft will push the balloon in the direction the wind is going, so the anchor rope should be at an angle relative to the ground.  When you drop the parachute, those same winds should keep the parachute/payload pushed clear of the anchor rope.  So long as the drag rope connecting the payload to the anchor rope is sufficiently long and the mechanism connecting the drag rope to the anchor rope is sufficiently slippery, you shouldn't have a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I worry about Energizer777's solution though.  Mainly because the rope might be angled because of the winds aloft, as stated before.  Payloads on a parachute like to hang right below the parachute (more or less), and if the angle on the rope is sufficient the payload will simply end up resting on the rope itself, which might foul up and collapse the parachute since it's load will not be pulling on it properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of that being said, that solution &lt;em&gt;will&lt;/em&gt; work if you do this on a day with very calm, or non-existent wind...&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2015-10-21T16:05:16.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22257" PostTypeId="1" CreationDate="2015-10-21T19:46:41.273" Score="5" ViewCount="546" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Does Smeaton's coefficient, k, have a modern value or it is&#xA;dependent of the air density?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Why is the accepted value of k so high?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In various texts about the Wright brothers (see 1 and 2) one can read about Smeaton's coefficient that troubled them a lot and that they finally discovered the parameter had a much lower value reaching the conclusion $k = 0.0033 lbf/ft^2/mph^2 = 0.79 kg/m^3$ (instead of $k = 0.005$), a fact also noticed by others before them.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;the Wright brothers calculated a new average value of 0.0033.&#xA;Modern aerodynamicists have confirmed this figure to be accurate&#xA;within a few percent.&quot; &lt;a href=&quot;http://airandspace.si.edu/exhibitions/wright-brothers/online/fly/1901/smeaton.cfm&quot; rel=&quot;nofollow&quot;&gt;Source: Correcting Smeaton's&#xA;Coefficient&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;$L = k \cdot  S \cdot V^2 \cdot C_L$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L$ = lift in pounds&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$k$ = coefficient of air pressure (Smeaton coefficient)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$S$ = total area of lifting surface in square feet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V$ = velocity (headwind plus ground speed) in miles per hour&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_L$ = coefficient of lift (varies with wing shape)&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Wright_brothers&quot; rel=&quot;nofollow&quot;&gt;Source: The Wiki page of the Wright brothers&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, knowing that the modern formula for lift is &#xA;$$L = 0.5 \cdot \rho \cdot S \cdot V^2 \cdot C_L$$&#xA;Where $\rho$ = the air density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that $k = 0.5 \cdot \rho$ and so it does not have a standard average value. Also a $k = 0.0033 lbf/ft^2/mph^2 = 0.79 kg/m^3$ leads to a $\rho = k/0.5 = 1.58 kg/m^3$ that corresponds to a sea level air temperature well below -25 C, which is unusual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the two relations for lift are correct, the Smeaton's coefficient can not be 0.0033 but closer to 0.0025 a value corresponding to a standard air density at $20 ^\circ C$ close to $1.2 kg/m^3$.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="4197" LastEditDate="2015-10-22T07:33:27.710" LastActivityDate="2021-01-31T15:56:17.303" Title="Does Smeaton's coefficient have a modern accepted value or it is dependent of the air density?" Tags="&lt;aerodynamics&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22258" PostTypeId="2" ParentId="22155" CreationDate="2015-10-21T20:16:10.810" Score="3" Body="&lt;p&gt;Probably the most common scenario would be switching from VFR to a code in the 75xx, 76xx or 77xx ranges when using a transponder with a control to set each individual digit (or each digit in order):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NcDxT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NcDxT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4fkWl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4fkWl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;(source: &lt;a href=&quot;http://www.aircraft-spruce.com/catalog/graphics/at165-unit.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft-spruce.com&lt;/a&gt;)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're squawking VFR (as most will be) on approach to a towered airfield and are assigned a squawk code 7625, if you're not paying attention you'll set the 7, then the 6, and at that point you'll be set to squawk 7600 (comms failure). Some IFF systems can interrogate an aircraft several times a second, so if you're set to 7600 even for a second it can cause an alert on the ATC system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To guard against this, The easiest way is to set the transponder to &quot;SBY&quot; to prevent it responding. As other answers/comments have said, this is questionable because it stops altitude reporting, which can be useful even if your squawk code is wrong while you're changing it. Another possibility with the older four-knob analog-display systems is to set your transponder's last digit first when changing from any XX00 code, and in normal left-to-right order when moving into an XX00 code. Say you're squawking VFR and ATC asks you to squawk 7625. Set the 5 first in the last digit, then the 2, then the 6 and finally the 7. You'll transition from 1200 to 1205 to 1225 to 1625 and finally 7625, all completely innocuous codes (though one might be a dupe of another assigned code; really no way to prevent this except to go to standby or just set the code quickly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also possible for newer digital systems to temporarily enter a standby-like mode while you're changing the code, making it harder to accidentally respond with the wrong code, including an emergency code, while you're still switching it. If you exit the code entry mode halfway through, it can still be an issue, and some of the digital systems mimic the four-knob style and so they don't really know when you're done.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="8282" LastEditDate="2019-02-09T11:33:40.897" LastActivityDate="2019-02-09T11:33:40.897" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="22259" PostTypeId="1" AcceptedAnswerId="22263" CreationDate="2015-10-21T20:20:36.537" Score="23" ViewCount="2456" Body="&lt;p&gt;Let's say an &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot;&gt;Osprey&lt;/a&gt; appears to be flying normally in forward flight. In preparation for landing, the pilot tries to command the engines to begin tilting to vertical, but nothing happens. What now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's a manual way to crank the engines up, that's not working either.&lt;/p&gt;&#xA;" OwnerUserId="11931" LastEditorUserId="62" LastEditDate="2015-10-22T23:08:56.390" LastActivityDate="2017-02-24T10:34:34.487" Title="If an Osprey found itself unable to rotate its engines to vertical, what would be the emergency procedure for landing?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;v-22&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22262" PostTypeId="2" ParentId="22257" CreationDate="2015-10-21T20:39:48.440" Score="4" Body="&lt;p&gt;There is no modern equivalent to the Smeaton coefficient, therefore it has no &quot;modern&quot; value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Smeaton coefficient is supposed to represent a &quot;coefficient of air pressure&quot; (and thus indirectly &lt;em&gt;density&lt;/em&gt;), but it is a false constant: There is no &lt;em&gt;single&lt;/em&gt; value because air pressure is not a constant value, but rather a variable (depending on altitude, temperature, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you noted lift is calculated by a different formula today, using actual density of the fluid (air) you're moving through in place of the Smeaton coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$ L = Cl \cdot \frac{(A \cdot \rho)}{2} \cdot V^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can calculate the Smeaton coefficient at any given location/altitude with simple algebra if you know the air density: Solve the modern lift equation, plug the values into the &quot;old&quot; Wright Brothers era equation, and solve for $k$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The density-based calculation also has the benefit of working in other fluids besides air. (The same equation can give you &lt;em&gt;hydrodynamic&lt;/em&gt; lift for boats and submarines by plugging in the density of water - itself a dynamic value depending on temperature, salinity, etc.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-21T20:39:48.440" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22263" PostTypeId="2" ParentId="22259" CreationDate="2015-10-21T21:28:44.063" Score="26" Body="&lt;p&gt;The Bell Helicopter &lt;a href=&quot;http://www.bellhelicopter.com/MungoBlobs/126/268/V-22%20Guidebook%202013_update_PREVIEW_LR2.pdf&quot; rel=&quot;noreferrer&quot;&gt;V-22 Guidebook&lt;/a&gt; covers survivability in Appendix 1.&lt;/p&gt;&#xA;&lt;p&gt;Specifically it refers to&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Redundant Fly-by-Wire Controls&lt;/p&gt;&#xA;&lt;p&gt;Redundant Electrical Power&lt;/p&gt;&#xA;&lt;p&gt;Redundant Hydraulics Swashplate&lt;/p&gt;&#xA;&lt;p&gt;Actuator Armor&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;implying that this possibility has been engineered to a minimum.&lt;/p&gt;&#xA;&lt;p&gt;Nevertheless, the premise of your question is that it's occurred, so further on in the same section we see&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;V-22 crashworthiness is a function of design. Heavy components,  such&#xA;as the engines and transmissions, are located away from  the cabin and&#xA;cockpit area. &lt;strong&gt;The proprotors are designed to fray or  “broomstraw”&#xA;rather than splinter on impact with the ground&lt;/strong&gt;. The  energy-absorbing&#xA;landing gear system is designed to attenuate  most of the energy for&#xA;hard landings up to 24 fps. The wing is  constructed to fail outboard&#xA;of the wing/fuselage attachment in a  manner that absorbs kinetic&#xA;energy and ensures the cabin area will  not be crushed, thereby&#xA;protecting the occupants. An anti-plow  bulkhead prevents the nose&#xA;from digging in on impact, and the  fuselage provides a reinforced&#xA;shell that is designed to maintain 85%  of its volume during a crash.&#xA;Aircrew and embarked troops receive  additional protection from&#xA;crashworthy seats that stroke vertically to  absorb energy&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(my emphasis)&lt;/p&gt;&#xA;&lt;p&gt;Since the aircraft is still flying, I'd head for the nearest decently equipped airfield, conduct a normal fixed wing approach and land, trusting that the rotors will sweep a nice clean path along the runway instead of peppering the fuselage with shrapnel. I'd probably take the precaution of cutting power early to reduce the kinetic energy in the rotors before they hit the ground.&lt;/p&gt;&#xA;" OwnerDisplayName="user11933" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-21T21:28:44.063" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="22264" PostTypeId="1" AcceptedAnswerId="22284" CreationDate="2015-10-21T21:41:49.567" Score="4" ViewCount="1533" Body="&lt;p&gt;If a plane is flying VFR (see and avoid) below 400 ft, and the pilot collides with a drone due to not seeing the drone until it's too late to take evasive action, then would the pilot be at-fault for insurance purposes? Would the drone operator (or the pilot) have violated any federal regulations for not keeping clear of the other craft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conditions:-&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Class E or G airspace&lt;/li&gt;&#xA;&lt;li&gt;out of the 5nm radius of an airport&lt;/li&gt;&#xA;&lt;li&gt;sparsely populated area&lt;/li&gt;&#xA;&lt;li&gt;operator of drone is &lt;em&gt;not&lt;/em&gt; within 500 ft of where the collision occurred (i.e. for the purposes of FAR &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/b4a0cab3e513bb58852566c70067018f/91693c93525de33e862576c100763e31!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;91.119 (c)&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;I have a smaller piston engine plane in mind, but I'm assuming that the outcome would be the same for faster jet aircraft too&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="995" LastEditorUserId="19" LastEditDate="2017-03-02T16:16:07.933" LastActivityDate="2017-03-02T16:16:07.933" Title="In case of a drone strike with an airplane below 400 feet, who is at fault?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22265" PostTypeId="2" ParentId="8306" CreationDate="2015-10-21T21:59:22.740" Score="5" Body="&lt;p&gt;Your Casio has an answer, but not &lt;em&gt;the&lt;/em&gt; answer. It's detecting pressure change, as the pressure does decrease no matter what when gaining height in a plane, (which is why your ears pop,) from roughly 6000 to 8000 feet worth of pressure. Your watch can pick up on this change, but you won't often be flying at a height with the same pressure as the cabin. I note that you didn't say the figure, which would probably reveal that the cabin was changing in pressure, and thus altitude reading, but not what your &lt;em&gt;real&lt;/em&gt; height was, i.e, the pressure outside of the plane.&lt;/p&gt;&#xA;" OwnerUserId="11914" LastActivityDate="2015-10-21T21:59:22.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22266" PostTypeId="2" ParentId="22264" CreationDate="2015-10-21T22:09:40.490" Score="-6" Body="&lt;p&gt;&lt;em&gt;Drone strike with plane below 400 feet - who's at fault?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this article (&lt;a href=&quot;http://www.techtimes.com/articles/21223/20141201/faa-to-drone-operators-keep-off-airports-stay-below-400-feet.htm&quot; rel=&quot;nofollow&quot;&gt;FAA to Drone Operators: Keep Off Airports, Stay Below 400 Feet&lt;/a&gt;) it appears that the pilot of the plane is guilty for the collision. If the drone operator respected the FAA rules (line of sight, below 400 ft and max. allowed weight, far from the airports) he can not be declared guilty for the accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Federal Aviation Administration (FAA) chief Michael Huerta says the agency already has regulations in place to ensure safety in the skies.&#xA;Huerta says the agency already has rules that prohibit operators of personal drones from flying into airports and soaring over 400 feet in the air.&lt;/em&gt;, &lt;a href=&quot;http://www.techtimes.com/articles/21223/20141201/faa-to-drone-operators-keep-off-airports-stay-below-400-feet.htm&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-21T22:25:05.833" LastActivityDate="2015-10-21T22:25:05.833" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22269" PostTypeId="1" AcceptedAnswerId="22291" CreationDate="2015-10-21T22:26:29.263" Score="13" ViewCount="6904" Body="&lt;p&gt;For a given propeller size (say 5&quot;), what is the minimum clearance needed between propellers to ensure that not only do they not hit each other (easy to calculate), they also don't interfere too much with each other (i.e. tip vortices, airflow, etc.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example consider the following design: an X-shaped quad-copter where the propellers are at the end of each tip of the X - and the X across the diagonal (max distance from the center of the propellers) is 180mm - then 5&quot; propellers will only have .279mm of clearance between them - now assuming that mechanically there are no vibrations/imperfections/etc. that cause them to run into each other, what else is there to avoid in terms of airflow? if they were raised such that two diagonal propellers are lower/higher than the others, would there be any issues? does it depend on the propeller pitch, or if it's a 2-blade or 3-blade propeller? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/85G8o.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/85G8o.jpg&quot; alt=&quot;Propeller Arrangement&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. - I am unsure of the tags, please adjust as necessary &lt;/p&gt;&#xA;" OwnerUserId="3557" LastActivityDate="2017-01-26T16:15:38.497" Title="How much distance do I need between quadcopter propellers to avoid issues?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22271" PostTypeId="1" AcceptedAnswerId="22280" CreationDate="2015-10-21T23:14:47.033" Score="4" ViewCount="3319" Body="&lt;p&gt;I'm trying to understand how an IFR flight an ACC (center) controller communicates the hand over to the pilot to contact local airport frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried listening LiveAtc but my English is not so good and I still have a couple of questions. I must emulate a center hand over to local destination frequencies, is this order correct for pickup the right frequency? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approach (if present)&#xA;Departure (if present)&#xA;Tower&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is departure eligible if an approach frequency is not available?&#xA;If approach is available, which ATC gives landing clearances, tower or approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also at which distance from airport ACC should do the hand off to the approach frequency?&lt;/p&gt;&#xA;" OwnerUserId="11934" LastEditorUserId="572" LastEditDate="2015-10-22T10:19:16.623" LastActivityDate="2015-10-22T10:19:16.623" Title="When is an aircraft handed over from Center to Approach?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;radio-communications&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22272" PostTypeId="2" ParentId="22213" CreationDate="2015-10-21T23:35:13.893" Score="0" Body="&lt;p&gt;The problem is that you can't fix the angle with a single beam. Instead, use the following setup (90 degrees rotated for ASCII art):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;            ,&amp;lt;)           __&#xA;/___________A____________/  \&#xA;\                        \__/&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;That is to say, use two beams to guide two rings along the anchor rope, and connect the parachute to the top of the A. Furthermore, connect the payload to the middle of the A (below the connecting bar) to balance the air friction of the parachute and the rope friction on the other side. This reduces the tilting torque.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-10-21T23:35:13.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22275" PostTypeId="1" AcceptedAnswerId="22279" CreationDate="2015-10-22T00:49:20.357" Score="15" ViewCount="3642" Body="&lt;p&gt;I'd like for this question's answers to be a references of the mnemonic devices pilots can use to assist with memorization of the equipment required by the FAA for flight in powered civil aircraft. What are the common mnemonic devices used to remember equipment required by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.2.91_1205&amp;amp;rgn=div8&quot;&gt;14 CFR 91.205&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-22T02:13:40.667" LastActivityDate="2015-10-22T02:13:40.667" Title="What are the common mnemonic devices used to remember equipment required by 14 CFR 91.205?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22276" PostTypeId="1" AcceptedAnswerId="22283" CreationDate="2015-10-22T00:58:07.020" Score="3" ViewCount="338" Body="&lt;p&gt;What do pilots operating under FAA 14 CFR 91 have to do to fly in any of the Special Flight Rules Areas (SFRA). Does each SFRA have its own requirements? I know there's a &lt;a href=&quot;https://aviation.stackexchange.com/q/1546/8490&quot;&gt;question already&lt;/a&gt; about the &lt;a href=&quot;https://aviation.stackexchange.com/q/1546/8490&quot;&gt;Washington DC SFRA&lt;/a&gt;. Is there a master list of these areas with corresponding requirements?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-23T18:36:59.217" Title="What do pilots operating under FAA 14 CFR 91 have to do to fly in any of the Special Flight Rules Areas (SFRAs)?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22277" PostTypeId="1" AcceptedAnswerId="22282" CreationDate="2015-10-22T01:33:34.213" Score="4" ViewCount="365" Body="&lt;p&gt;I heard during an aviation presentation that full nose-up trim provides approximately the right amount of elevator pressure for Vg with the power at flight idle. The presenter also followed up with that this is a certification requirement. Is this the case? Is there anything in 14 CFR 23 or 25 about it?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-22T06:41:05.750" Title="Does full nose up trim provide approximately the elevator pressure for Vg?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22279" PostTypeId="2" ParentId="22275" CreationDate="2015-10-22T01:44:28.220" Score="19" Body="&lt;p&gt;For VFR Day Flights, you can use &quot;&lt;strong&gt;A TOMATO FLAMES&lt;/strong&gt;&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Altimeter&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;T&lt;/strong&gt; - Tachometer for each engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;O&lt;/strong&gt; - Oil temp indicator for each engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;M&lt;/strong&gt; - Manifold pressure gauge for each altitude engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Airspeed indicator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;T&lt;/strong&gt; - Temperature gauge for each liquid cooled engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;O&lt;/strong&gt; - Oil Pressure gauge for each engine&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;F&lt;/strong&gt; - Fuel quantity gauge for each tank&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;L&lt;/strong&gt; - Landing gear position lights (if retractable gear)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Anti-collision lights (aircraft certificated after March 11, 1996)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;M&lt;/strong&gt; - Magnetic direction indicator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;E&lt;/strong&gt; - ELT, if required by §91.207&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;S&lt;/strong&gt; - Safety belts / Shoulder harnesses&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For VFR Night Flights, you can use &quot;&lt;strong&gt;FLAPS&lt;/strong&gt;&quot;. This will be in addition to all the equipment required for a VFR Flight in Daylight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;F&lt;/strong&gt; - Fuses (spare set)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;L&lt;/strong&gt; - Landing light (if for hire)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Anti-collision light&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P&lt;/strong&gt; - Position lights (navigation lights)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;S&lt;/strong&gt; - Source of power (such as battery)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Additionally, as @wbeard52 pointed out below, you can use &quot;&lt;strong&gt;GRABCARD&lt;/strong&gt;&quot; as a mnemonic device to memorise the equipment required for IFR Flight. Again, these would be in addition to all the equipment required for VFR Day and Night Flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;G&lt;/strong&gt; - Generator/alternator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;R&lt;/strong&gt; - Radios (two way and navigational equipment&#xA;appropriate for the ground facilities to be used)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Altimeter (sensitive) adjustable for barometric pressure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B&lt;/strong&gt; - Ball (slip-skid indicator, which is part of your turn coordinator)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;C&lt;/strong&gt; - Clock (shows hours minutes and seconds and installed as part of aircraft equipment)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A&lt;/strong&gt; - Attitude indicator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;R&lt;/strong&gt; - Rate of turn indicator&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;D&lt;/strong&gt; - Directional gyro (Heading indicator)&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="11136" LastEditDate="2015-10-22T01:51:10.977" LastActivityDate="2015-10-22T01:51:10.977" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22280" PostTypeId="2" ParentId="22271" CreationDate="2015-10-22T06:07:55.723" Score="8" Body="&lt;p&gt;In general, aircraft are handed over on frequency to the next controller via a simple instruction to change the frequency:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;R: &quot;Lufthansa One Two Tree, contact Langen Radar 128.550&quot;&lt;br&gt;&#xA;  A: &quot;Contact 128.550, Lufthansa One Two Tree&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The simplified order of contacted stations for a commercial flight, depending on availability and airspace structure is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Delivery (if available)  &lt;/li&gt;&#xA;  &lt;li&gt;Apron/Ground (if available)  &lt;/li&gt;&#xA;  &lt;li&gt;Tower  &lt;/li&gt;&#xA;  &lt;li&gt;Departure (if available, sometimes handled by Approach)  &lt;/li&gt;&#xA;  &lt;li&gt;Enroute ACC/Center (multiple stations along the route)  &lt;/li&gt;&#xA;  &lt;li&gt;Arrival/Approach  &lt;/li&gt;&#xA;  &lt;li&gt;Director (if available / in use)  &lt;/li&gt;&#xA;  &lt;li&gt;Tower  &lt;/li&gt;&#xA;  &lt;li&gt;Ground (if available)  &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The point and altitude or flightlevel where the handoff is initiated is agreed upon in Letters of Agreement between the different sectors or ACC/ARTCC stations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uPIFs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uPIFs.png&quot; alt=&quot;KAE Airspace Langen EDDK&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: SentryRaven - Own Work)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above picture shows the airspace around Köln/Bonn (EDDK) Airport, with the Köln Arrival East (KAE) sector being actively displayed in black. The STAR entry / clearance limit fixes are GULKO and KOPAG, in the east. Most traffic not arriving via NOR VOR in the west will terminate at these two fixes, which also serve as the handoff fix between the center controller (Paderborn High, Taunus and/or Rhein Radar Upper Control) and the arrival controller responsible for Köln East Sector. The Letter of Agreement between those sectors states that traffic arriving to Köln/Bonn via GULKO and KOPAG is to be cleared to FL100 and cleared for the respective STAR out of GULKO or KOPAG. The handoff is initiated approaching FL100 and approaching the entry fix, before the sector boundary. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The handoff is therefore based on airspace structure and sector boundaries, not on a preset distance from the airport. While arrivals from the east are handed off at FL100 over GULKO and KOPAG, arrivals from the west at NOR VOR are handed off at FL140-FL170.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Landing and Take-Off clearances are issued by the Tower controller, as the approach controller is not necessarily based at the same airport but in most cases in a remote facility together with other approach and center controllers. They have no visibility of the airport and can thus not issue these clearances. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The handoff to Tower usually happens when the aircraft is established on the final approach segment of the published approach (usually after passing the Final Approach Fix (FAF)) or a visual approach to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The phraseology is the same as above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;R: &quot;Germanwings Two Six Alpha, contact Tower 124.975&quot;&lt;br&gt;&#xA;  A: &quot;124.975, Germanwings Two Six Alpha&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-10-22T07:13:04.867" LastActivityDate="2015-10-22T07:13:04.867" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22282" PostTypeId="2" ParentId="22277" CreationDate="2015-10-22T06:41:05.750" Score="5" Body="&lt;p&gt;This technique is commonly called the &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2006/July/200607_Features_The_minimum_trim_glide.html&quot; rel=&quot;noreferrer&quot;&gt;&quot;minimum trim glide&quot;&lt;/a&gt; - basically you smoothly trim the aircraft to full nose-up after the engine quits (at a rate which won't cause it to &quot;balloon&quot;), or alternatively you establish best glide speed manually and then trim to full nose-up to relive the pressure on the yoke so you can concentrate on other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if this is a &quot;certification requirement&quot; (I can't find anything about it in Part 23's discussion of trim requirements, the old CAR 3 regulations, or in &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1019676&quot; rel=&quot;noreferrer&quot;&gt;AC 23-8C&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Empirically I can tell you that it's true for the loading configurations I've tried it in, on the Piper PA-28 and Cessna 172 aircraft I've flown. I have been lead to believe it is generally true for single-engine piston light aircraft: With no engine thrust full nose-up trim will produce something &lt;em&gt;close&lt;/em&gt; to best glide speed. Before relying on it in any particular type of aircraft however I would perform a test at altitude by bringing the power to idle and verifying that you get something reasonably close to best glide speed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that there is a potential pitfall of the minimum trim glide when &lt;em&gt;practicing&lt;/em&gt; engine out maneuvers: Upon recovery it is possible to cause a trim stall. As power and airspeed increases in the recovery elevator/trim authority is also increased, and full nose-up trim is generally adequate to cause the aircraft to stall in this situation, therefore special care must be taken to prevent the aircraft from pitching up to an attitude which would cause a stall.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-22T06:41:05.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22283" PostTypeId="2" ParentId="22276" CreationDate="2015-10-22T06:51:46.677" Score="3" Body="&lt;p&gt;The &quot;master list&quot; of special flight rules areas (SFRAs) in the United States is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr93_main_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 93 (14CFR93)&lt;/a&gt;) - aptly named &quot;Special Air Traffic Rules&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains a list of areas with &quot;Special Air Traffic Rules&quot;, including the requirements for operating in those areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Charts with SFRAs on them include a notice directing you to FAR 93 (and often other helpful information about the SFRA):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/tQR7x.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tQR7x.png&quot; alt=&quot;NY SFRA note box&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In addition to &quot;Special Air Traffic Rules&quot; some airspace with &quot;special&quot; rules may be defined by &quot;Special Federal Aviation Regulations&quot; (SFARs), found at the beginning of Part 91.&lt;br&gt;&#xA;The only one I see in there currently is the Grand Canyon National Park SFAR.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-22T06:51:46.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22284" PostTypeId="2" ParentId="22264" CreationDate="2015-10-22T13:59:48.367" Score="8" Body="&lt;p&gt;The FAA has some rules pending about this, you can read &lt;a href=&quot;https://www.faa.gov/regulations_policies/rulemaking/recently_published/media/2120-AJ60_NPRM_2-15-2015_joint_signature.pdf&quot; rel=&quot;noreferrer&quot;&gt;them here&lt;/a&gt; but for drones under 55 LBS one of the proposed rules is, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Must yield right-of-way to other aircraft, manned or unmanned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and since you bring up class E it should be noted that &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Operations in Class B, C, D and E airspace are&#xA;  allowed with the required ATC permission.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;if/when this goes through it looks like its the drone operators fault since the plane had the right of way &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/uas/publications/model_aircraft_operators/&quot; rel=&quot;noreferrer&quot;&gt;FAA's website in relation to model aircraft&lt;/a&gt; they state that, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(4) the aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;this is pretty much a blanket statement that maned aircraft have the right of way but the FAA handles most things on a case by cases basis so in the end of the day it could go either way. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-22T16:01:01.197" LastActivityDate="2015-10-22T16:01:01.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22285" PostTypeId="1" CreationDate="2015-10-22T15:04:21.057" Score="15" ViewCount="3566" Body="&lt;p&gt;The warning above the big white switches in the following picture had me intrigued. Is there some FAA regulation related to the same?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BmJjy.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BmJjy.png&quot; alt=&quot;WARNING: Airconditioner must be off to insure normal takeoff climb performance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-10-23T02:41:19.227" LastActivityDate="2015-10-23T02:41:19.227" Title="Is there an FAA regulation to switch off the air-conditioning during take off?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22286" PostTypeId="2" ParentId="22285" CreationDate="2015-10-22T15:46:42.180" Score="19" Body="&lt;p&gt;As far as I know there is no specific regulation covering Air Conditioner operation however this varies from aircraft to aircraft and you should always check your specific aircrafts POH for information on systems installed and how they are to be operated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In specific regards to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot;&gt;Piper Archer&lt;/a&gt; (pictured here) the &lt;a href=&quot;http://www.aceflyingclub.com/manuals/piper-PA-28-181-POH.pdf&quot;&gt;POH states&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On air conditioned models, the air conditioner must be “OFF” to ensure normal takeoff performance. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In terms of why that is there, Air Conditioner units use engine power to run (they are basically heat pumps). In smaller aircraft, especially on the slower/low power end of the spectrum (like the archer pictured here) taking away HP to run an AC unit can mean the difference between clearing a 50ft obstacle and not clearing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for FAA regulations, the FAA does outline procedures for &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC25-13.pdf&quot;&gt;certifying a plane for reduced thrust takeoffs&lt;/a&gt;, however this involves power setting alterations. Depending on how you look at it running the Air Conditioner is in a way a reduced power takeoff however since you cant specifically adjust Air Conditioner power draw (as far as I know) running it could draw an unknown and potentially variant amount of power.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-22T15:53:20.127" LastActivityDate="2015-10-22T15:53:20.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22287" PostTypeId="2" ParentId="22285" CreationDate="2015-10-22T16:00:17.940" Score="27" Body="&lt;p&gt;It is not an FAA regulation to have the air conditioning off during takeoff and/or landing, however some manufacturers require it, in which case the pilot is legally obligated to comply with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have flown two aircraft (both jets) which required it to be off:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some of the Learjets require the AC to be off for both takeoff and landing because it uses a high draw electrical motor to drive the compressor, and when it cycles off and on it causes electrical spikes which can cause problems with the anti-skid system.&lt;/li&gt;&#xA;&lt;li&gt;Some of the Dassault Falcon jets require the AC to be off for takeoff (actually, they automatically turn it off, but if the automatic system is inoperative the MEL requires turning it off manually) for performance reasons.  Since the AC is these aircraft is using bleed air off of the engine compressor as a source, allowing the air to continue through the engine instead increases thrust.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I know that many airliners have the option to takeoff with it on or off for performance reasons, and provide performance charts or adjustments for both.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-10-22T16:00:17.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22288" PostTypeId="1" AcceptedAnswerId="22289" CreationDate="2015-10-22T20:01:22.313" Score="15" ViewCount="5876" Body="&lt;p&gt;On &lt;a href=&quot;https://aviation.stackexchange.com/q/22271/8730&quot;&gt;this question&lt;/a&gt; SentryRaven gave the following list of ATC stations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Delivery (if available)&lt;/li&gt;&#xA;&lt;li&gt;Apron/Ground (if available)&lt;/li&gt;&#xA;&lt;li&gt;Tower&lt;/li&gt;&#xA;&lt;li&gt;Departure (if available, sometimes handled by Approach)&lt;/li&gt;&#xA;&lt;li&gt;Enroute ACC/Center (multiple stations along the route)&lt;/li&gt;&#xA;&lt;li&gt;Arrival/Approach&lt;/li&gt;&#xA;&lt;li&gt;Director (if available / in use)&lt;/li&gt;&#xA;&lt;li&gt;Tower&lt;/li&gt;&#xA;&lt;li&gt;Ground (if available)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I am not familiar with &lt;strong&gt;Director&lt;/strong&gt;. What does this ATC position do and when is it used?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-10-15T03:02:42.290" Title="What is &quot;Director&quot; in ATC?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22289" PostTypeId="2" ParentId="22288" CreationDate="2015-10-22T20:14:04.113" Score="11" Body="&lt;p&gt;Some TMA arrival sectors can be further split up into an arrival/pickup part and a director/feeder part.&lt;/p&gt;&#xA;&lt;p&gt;The arrival controller is responsible for getting aircraft separated either onto downwinds or onto transitions, where they are handed off to the director. The director is then only responsible for turning these aircraft onto the approach, in most cases the ILS.&lt;/p&gt;&#xA;&lt;p&gt;Essentially, the arrival or pickup tries to get everyone onto the correct separation and speeds, so the director or feeder can turn and clear the aircraft onto their approaches, i.e. feeding the ILS with aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TdRY2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TdRY2.png&quot; alt=&quot;EDDF Director&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: SentryRaven - Own Work)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The above picture shows the TMA airspace of Frankfurt (EDDF). The TMA arrival controller would clear aircraft onto the transition or a vectored downwind and hand them over to director.&lt;/p&gt;&#xA;&lt;p&gt;The director position would then vector the aircraft onto the ILS for a handoff to tower.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-22T20:21:04.820" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22291" PostTypeId="2" ParentId="22269" CreationDate="2015-10-23T01:19:16.857" Score="6" Body="&lt;p&gt;Well, you gotta keep in mind that the airflow is mainly down, but there will always be a little flow side to side, (thus frames, also used for safer collisions,) so you should put them roughly 1/3 of the diameter of the rotors themselves away from each other. This provides enough space to keep your interference down, as the interference spreads  out to about 1/4 of the radius of the rotor. I have not seen that the number of blades matters much, as long as you follow the 1/3 diameter rule. You want to avoid the counter- airflow that can make your craft less efficient or jack the blades. Note also that raising two of the blades would cause &lt;em&gt;serious&lt;/em&gt; problems with your efficiency, because two rotors blowing downwards in a cone, unless very effectively controlled, will &lt;em&gt;kill&lt;/em&gt; the stability, creating unnecessary strain, or in bad cases, frame torque. The two above would create interference for the lower. This could, however, be avoidable if the top two were about 3/4  rotor diameter away, and no higher than 1/4 a rotor diameter. But then you'd be flying a very odd and somewhat unbalanced copter.&lt;/p&gt;&#xA;" OwnerUserId="11914" LastEditorUserId="11914" LastEditDate="2017-01-26T16:15:38.497" LastActivityDate="2017-01-26T16:15:38.497" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22292" PostTypeId="2" ParentId="22144" CreationDate="2015-10-23T02:43:46.380" Score="12" Body="&lt;p&gt;Okay guys, the verdict is in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a symbol to indicate the crew alerting chimes are inhibited.&#xA;From OUT (off block) until OFF+15 and estimated ON-10 until IN (on block) the chimes to alert for new data and messages are suppressed to avoid nuisance warnings during critical flight phases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Happy landings!&lt;/p&gt;&#xA;" OwnerUserId="11876" LastActivityDate="2015-10-23T02:43:46.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22293" PostTypeId="1" CreationDate="2015-10-23T03:07:21.697" Score="0" ViewCount="640" Body="&lt;p&gt;It seems odd that a large commercial aircraft can deviate radically from its scheduled flight path without the military doing something about the situation. Malaysian military radar tracked the plane for about an hour after said aircraft had dropped off the air traffic controllers radar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why were no jets scrambled?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has Malaysia not heard of &quot;9/11&quot;, and how commercial aircraft were used by terrorists? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which other countries military also pays such little heed &quot;9/11&quot;?&lt;/p&gt;&#xA;" OwnerUserId="11956" LastActivityDate="2015-10-23T03:35:29.190" Title="Malaysia Airlines Flight 370 - Why didn't Malaysian Air Force scramble jets?" Tags="&lt;military&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-10-23T05:44:24.877" ContentLicense="CC BY-SA 3.0" />
  <row Id="22294" PostTypeId="2" ParentId="22293" CreationDate="2015-10-23T03:35:29.190" Score="6" Body="&lt;p&gt;There are multiple reasons for this:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft stopped communicating &lt;em&gt;after&lt;/em&gt; the Kula Lumpur asked the aircraft to contact Ho Chi Minh ACC. The last verbal contact with the aircraft is this:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Lumpur Radar: &amp;quot;Malaysian three seven zero, contact Ho Chi Minh one two zero decimal nine. Good night.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Flight 370: &amp;quot;Good night. Malaysian three seven zero.&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The Kula Lumpur Control had no way of knowing whether the aircraft had contacted as instructed (and acknowledged).&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;According to the &lt;a href=&quot;http://www.cbc.ca/news/world/malaysia-airlines-mh370-defence-ministry-defends-not-sending-jet-1.2647197&quot; rel=&quot;noreferrer&quot;&gt;Malaysian defence minister&lt;/a&gt;, the aircraft was deemed commercial and not hostile.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even if the aircraft was tracked in radar by the military, that in itself is not sufficient for scrambling jets. Usually, the ATC will inform the authorities about any possible deviation; It is unlikely that the military would have real time details of aircraft routes. Note that it was not possible in this case (the aircraft transponder had gone silent before deviating from path). Also, there can be multiple reasons for loss of communications (usually equipment failure), and one does not immediately conclude that the aircraft has been hijacked.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scrambling jets is usually the last resort and are sent to &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/listen-to-the-threat-youll-hear-if-you-screw-with-briti-1652997879&quot; rel=&quot;noreferrer&quot;&gt;shoot the non-responsive aircraft&lt;/a&gt;. You don't shoot a civil aircraft with hundreds of passengers just because a microphone stopped working. The ATC must confirm that it had deviated from path and then the aircraft must be deemed a credible threat.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;While the procedures for scrambling military aircraft are usually classified, it can be assumed that they are different in case of US (and Europe) and rest of the world. It takes a lot of resources to keep aircraft and pilots ready to intercept aircraft, which not all countries have (or even require most of the time).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-23T03:35:29.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22297" PostTypeId="1" CreationDate="2015-10-23T07:20:11.757" Score="6" ViewCount="15686" Body="&lt;p&gt;What are the normal climbing angles against ground on a SEP (single engine piston) plane and an airliner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(no wing-air angles in here, but the climb angle when watched from the side of the plane)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wNxBt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wNxBt.jpg&quot; alt=&quot;OwnWorkAngle&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: user11961 - Own Work)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="11961" LastEditorUserId="1696" LastEditDate="2015-10-25T00:38:18.307" LastActivityDate="2015-10-25T00:38:18.307" Title="What is the typical climb angle (versus the ground) of a single engine piston plane?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;climb&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22298" PostTypeId="1" AcceptedAnswerId="22302" CreationDate="2015-10-23T08:00:43.143" Score="0" ViewCount="3531" Body="&lt;p&gt;Another &lt;a href=&quot;https://aviation.stackexchange.com/questions/22296/aircraft-movement-in-and-out-of-hangar&quot;&gt;question&lt;/a&gt; talks about aircraft movement in and out of hangar.  Most hangar I see at commercial airport I see one aircraft per hangar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This makes me wonder how many aircraft can be kept in the hangar depth-wise(ie nose-to-tail direction)? Is larger hangar common? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;Sub&gt;Note: please do not include special hangars such as those at Airbus or Boeing facility in main answer but side note about those are welcomed.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-10-23T09:45:33.210" Title="How many aircraft can airline put in hangar?" Tags="&lt;airline-operations&gt;&lt;hangar&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-10-23T14:24:14.133" ContentLicense="CC BY-SA 3.0" />
  <row Id="22299" PostTypeId="2" ParentId="22297" CreationDate="2015-10-23T08:03:32.090" Score="6" Body="&lt;p&gt;That depends on wind speed and the aircraft's thrust-to-weight ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some values, all valid for sea level&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;GA aircraft: 4 m/s climb speed, 36 m/s airspeed. In calm air, this becomes a climb angle of 6.3°. If the wind blows with 36 m/s, the aircraft will climb vertically relative to earth if it flies straight into the wind.&lt;/li&gt;&#xA;&lt;li&gt;Airliner: 20 m/s climb speed, 120 m/s. In calm air this becomes a climb angle of 9.5°.&lt;/li&gt;&#xA;&lt;li&gt;Empty airliner: 30 m/s at 100 m/s. In calm air this becomes a climb angle of 16.7°. At airshows &lt;a href=&quot;https://aviation.stackexchange.com/questions/16112/boeing-vs-airbus-boeing-787-9-near-vertical-takeoff&quot;&gt;this is used to dramatic effect&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that the spectacular angles at airshows involve the conversion of airspeed to altitude, so these maneuvers are instationary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know more on computing the optimum climb angle, &lt;a href=&quot;https://aviation.stackexchange.com/questions/21350/maximum-angle-of-climb-jet-vs-prop/21360?s=1%7C0.1297#21360&quot;&gt;consider reading this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main influence on climb speed is the thrust-to-weight ratio of the airplane. Since thrust depends on flight speed, ambient temperature and air density, those factors control the attainable climb speed in combination with the aircraft's weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an observer, the next important influence is wind speed, since the aircraft climbs relative to the air mass it is flying through. If this air mass makes the aircraft appear to fly more slowly, a steeper climb angle can be observed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B2BV1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B2BV1.png&quot; alt=&quot;Climb performance over airspeed and thrust-to-weight ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Climb performance over airspeed and thrust-to-weight ratio for an idealized turbofan engine. The blue lines show thrust (right Y-axis) and the green lines the resulting climb speed. The two black lines show how the optimum flight speed for best climb speed and best climb angle (steepest climb) vary over thrust loadings. They are easy to find graphically: Just measure the angle of a line from the origin to the point on a green line at the desired flight speed and the right thrust loading (thrust-to-weight ratio). If the scales of the two speeds on the X- and Y-axis would be the same, you could directly take the angle from the plot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With lots of excess thrust, the optimum is limited by the stall speed (the black line bends into a vertical trend), while with no excess thrust both optimum speeds vx and vy converge. This makes sense: If thrust is just sufficient to keep the airplane from descending at one speed, this speed will both give the best flight path angle and the best vertical speed (unfortunately, both will be 0 at this point). It also helps to reduce induced drag, so aircraft with a high aspect ratio wing will climb steepest at a higher lift coefficient (= lower speed).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-10-23T13:47:09.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22300" PostTypeId="2" ParentId="22298" CreationDate="2015-10-23T08:19:34.460" Score="2" Body="&lt;p&gt;There are no restrictions. You can put as many aircraft into a hangar as you can fit into it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some commercial hangars are neatly arranged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VPm6U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VPm6U.jpg&quot; alt=&quot;CommHangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some are not as neatly arranged but efficiently packed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dbtwi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dbtwi.jpg&quot; alt=&quot;GAHangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And sailplanes can be lifted and hung from the ceiling for more space on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IoFLQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IoFLQ.jpg&quot; alt=&quot;SailHangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-10-23T08:32:00.150" LastActivityDate="2015-10-23T08:32:00.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22301" PostTypeId="2" ParentId="22232" CreationDate="2015-10-23T09:08:05.357" Score="10" Body="&lt;p&gt;If I add raised wingtips to one of my RC planes they significantly decrease  the aileron authority, meanwhile improving the dihedral effect and the self-stabilizing tendency. But for maneuverability, it's not as good. If I add an autopilot, like Ardupilot, the raised wingtips will make harder for the autopilot to instantly correct the leveling when passing through turbulence, because the effect of the ailerons is dampened by the self-leveling tendency. Basically, the ailerons have to fight not only to change the attitude of the wing, but against it's tendency to rotate by itself, that might not act in the right direction when flying through turbulent air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I add dropped wingtips, they improve lift (the same wing is capable to carry more weight) and they increase greatly aileron authority, while decreasing passive auto-leveling.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Bt6LT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bt6LT.jpg&quot; alt=&quot;my plane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BAVGr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BAVGr.jpg&quot; alt=&quot;wingtip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane becomes harder to fly manually, but for the autopilot the effect is good, because the smallest deflection of the ailerons will have a big effect. The autopilot is capable to correct instantly the horizontal attitude of the wing, by moving the ailerons very fast, and in minute increments. The plane will look like it's flying on rails, even when it passes through turbulence. And the lower the altitude, the greater the turbulence, because the wind is moving over ground obstacles and it's not flowing laminarly. When the wind is strong and there are bushes and trees on the terrain, the turbulence can be so great, that a RC model can become impossible to fly low if it doesn't have some sort of electronic self-leveling device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The conclusion is that, for a plane that has to fly low, dropped wingtips and an active self-leveling device are the best combination. If the plane was low wing - high CG, I would have used raised wingtips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/73w9A.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/73w9A.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DiPV8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DiPV8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11962" LastEditorUserId="5517" LastEditDate="2015-10-26T16:37:14.603" LastActivityDate="2015-10-26T16:37:14.603" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22302" PostTypeId="2" ParentId="22298" CreationDate="2015-10-23T09:40:11.683" Score="1" Body="&lt;p&gt;As many as possible. The number of aircraft will vary depending on the size, (wing) height above the ground, etc. Most commercial airliners put any number of aircraft as long as there is no problem of damage during movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the following image shows one Boeing 747 Dreamlifter (N780BA) parked between two Airbus A380’s inside Lufthansa Technik’s Fankfurt hangar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jxt4u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jxt4u.jpg&quot; alt=&quot;Lufthansa Hangar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airlinereporter.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hangars are usually on the larger side because they are designed and constructed keeping the larger aircraft in mind. Then smaller aircraft will have little problem fitting into that. This image shows the floor plan for an aircraft hangar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ivzq0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ivzq0.jpg&quot; alt=&quot;Floor Plan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: psp-architekten.de&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-23T09:45:33.210" LastActivityDate="2015-10-23T09:45:33.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22303" PostTypeId="2" ParentId="13513" CreationDate="2015-10-23T09:46:43.617" Score="8" Body="&lt;p&gt;I think it depends on what kind of airline you are working for. If you are a pilot in a low-cost airline, preceding answers are precise. But for example, my wife is a pilot at Lufthansa, and they have their own engineering, own maintenance, repair &amp;amp; overhaul divisions etc., so they have a lot of &quot;staff pilots&quot; who spend about 50% of their time in the offices. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;management pilots like fleet captains (the formal boss of the pilots of a specific a/c type)&lt;/li&gt;&#xA;&lt;li&gt;technical pilot (writing procedures, discussing with manufacturers etc.)&lt;/li&gt;&#xA;&lt;li&gt;project pilots (pilots with more background like IT or an MBA who can bring both worlds together)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The CEO of Lufthansa, Carsten Spohr, is a pilot himself, but do not think that he has any time to fly anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think most of the pilots like to fly, but some of them want to spend some time in the office either to be at home or to advance their careers.&lt;/p&gt;&#xA;" OwnerUserId="11963" LastActivityDate="2015-10-23T09:46:43.617" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22304" PostTypeId="1" CreationDate="2015-10-23T10:34:42.677" Score="3" ViewCount="299" Body="&lt;p&gt;I have an EASA LAPL (A) fixed wing pilots license and would like to know what the equivalent FAA license would be. &lt;/p&gt;&#xA;" OwnerUserId="11964" LastEditorUserId="572" LastEditDate="2015-10-23T11:08:03.487" LastActivityDate="2015-10-23T12:20:39.817" Title="Does the EASA LAPL(A) have a FAA equivalent?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;lapl&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22305" PostTypeId="1" AcceptedAnswerId="22306" CreationDate="2015-10-23T11:32:51.523" Score="9" ViewCount="3350" Body="&lt;p&gt;I know that F=fighter, A=attack, F/A=fighter/attack, B=bomber. I can not find any information on what YF stands for. This type of aircraft is usually an experimental aircraft, but why do modern aircraft use X instead of YF?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="62" LastEditDate="2017-12-06T18:04:05.420" LastActivityDate="2017-12-06T18:04:05.420" Title="What does YF stand for?" Tags="&lt;terminology&gt;&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22306" PostTypeId="2" ParentId="22305" CreationDate="2015-10-23T11:43:02.690" Score="26" Body="&lt;p&gt;The 'Y' in YF stands for prototype according to the &lt;a href=&quot;http://www.designation-systems.net/usmilav/afji16-401.pdf&quot;&gt;Tri-Service aircraft designation system&lt;/a&gt;. The 'F' stands for fighter, so YF stands for prototype-Fighter. These aircraft are operated by the US Department of Defense (USAF or USN).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_YF-22&quot;&gt;YF-22&lt;/a&gt; is the prototype (technology demonstrator) version of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot;&gt;F-22 Raptor&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_X-planes&quot;&gt;'X' series&lt;/a&gt; is the name given for strictly experimental aircraft; i.e. they are not prototypes.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-23T11:48:33.177" LastActivityDate="2015-10-23T11:48:33.177" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22307" PostTypeId="1" CreationDate="2015-10-23T11:52:38.117" Score="3" ViewCount="9340" Body="&lt;p&gt;Recently I was flying around my RC helicopter on a 40 $^\circ$F (4$^\circ$C).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point in the flight the rotor just stopped moving in mid-air and then I regained control back at ground level. I never had any issues before in warmer weather, so I assume it's a cold-weather related issue with this model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This leaves me with two questions: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Could something like this  happen in a full-size helicopter like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Robinson_R22&quot; rel=&quot;nofollow&quot;&gt;Robinson R22&lt;/a&gt;?&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;What effect does temperature have on helicopter performance in general?&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="1696" LastEditDate="2018-04-17T20:45:21.703" LastActivityDate="2020-05-08T16:35:06.803" Title="What effect does cold weather have on helicopter performance?" Tags="&lt;aircraft-performance&gt;&lt;helicopter&gt;&lt;temperature&gt;&lt;cold-weather&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22308" PostTypeId="2" ParentId="22304" CreationDate="2015-10-23T12:01:46.930" Score="2" Body="&lt;p&gt;I'm not sure about their equivalence (meaning one cannot fly in US with a LAPL right way), but the closest that comes is the Recreational Pilot license. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/part-61/subpart-D&quot; rel=&quot;nofollow&quot;&gt;requirements&lt;/a&gt; are roughly similar:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;30 hours flying experience; however, the &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.99&quot; rel=&quot;nofollow&quot;&gt;FAA requires 3 hours of solo flying&lt;/a&gt; and cross country requirements are slightly different.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.101&quot; rel=&quot;nofollow&quot;&gt;limitations&lt;/a&gt; are also roughly similar:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Recreational pilot license doesn't allow the pilot to have more than one passenger, while the LAPL does (upto three).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-23T12:01:46.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22309" PostTypeId="2" ParentId="22307" CreationDate="2015-10-23T12:08:28.877" Score="13" Body="&lt;p&gt;Cold weather definitely affects the performance of helicopters (as it does all aircraft), because it affects the density of the air they move through. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will ignore icing so let's assume dry air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift equation is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ L = \frac{1}{2} \rho V^2 S C_L $$&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$L$ = Lift&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$\rho$ = density of the air. &lt;/li&gt;&#xA;&lt;li&gt;$V$ = velocity of the aerofoil (rotor)&lt;/li&gt;&#xA;&lt;li&gt;$S$ = the wing area of the rotor &lt;/li&gt;&#xA;&lt;li&gt;$C_L$ = Coefficient of lift , which is determined by the type of rotor and angle of attack.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As you can see, lift is proportional to the density of the air and since density at any given altitude is inversely proportional to the temperature, the colder the air, the more dense it is.  So, for a given rotor, spinning at a given speed at a given altitude, the colder the air, the more lift is produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines also operate more efficiently when the air is colder since the density is higher and the charge of air/fuel introduced into the engine is greater. (&lt;a href=&quot;https://mechanics.stackexchange.com/questions/11097/how-does-cold-dry-weather-affect-horsepower&quot;&gt;See here for more information.&lt;/a&gt;&lt;br&gt;&#xA; Of course, this does not apply to your RCH apart from some effects on the efficiency of the batteries and motors (which may perform more poorly at lower temperatures).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in general, the colder it is, the higher the performance.  In most helicopters, the difference in performance on a cold, dry winter day is very noticeable and much better than on a humid, hot summer day. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth understanding the properties of air.  The colder the air, the lower the &lt;a href=&quot;http://www.weatherquestions.com/What_is_dewpoint_temperature.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;dewpoint&lt;/a&gt; so the less moisture it can contain.  Moisture in the air also lowers peformance.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The problems you encountered with your RC model aren't problems with helicopters in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Colder weather &lt;em&gt;does not&lt;/em&gt; make you more susceptible to vortex ring state (aside from some minor side effects): You would still only descend into the vortex if you did not pilot the helicopter correctly. (Note that you cannot enter vortex ring state with the rotors stopped since they are not producing a vortex.  Also note that on a real helicopter, if the rotors ever stop, they will not start again no matter what you do.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BTW, I'm being pedantic, but helicopters do not have propellors.  Technically, they are the same thing, but asking a helicopter pilot about the propellor annoys them, even if they don't show it.  It's as bad a calling a helicopter a &quot;chopper&quot;.  Only Arnie and Chuck get to call helicopters &quot;choppers&quot;.  And that's only because helicopter pilots are universally weedy and would get stomped by Arnie or Chuck if they argued.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:47:21.530" LastActivityDate="2015-10-25T09:10:36.740" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22310" PostTypeId="2" ParentId="22307" CreationDate="2015-10-23T12:17:55.380" Score="7" Body="&lt;p&gt;First, I don't think cold weather had anything to do the stopping of rotor. Probably a malfunction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Helicopters do face a number of problems during flight in cold conditions&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Ice accumulation in leading edges- Very few helicopters have leading edge anti-icing systems and are certified for flying in cold conditions (like North Sea).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The possibility of misting in windshield.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Whiteout conditions, usually while taking off and landing. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ice/Snow ingestion in engines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Icing and blockage of fuel lines etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Most of these have to do with icing and not with cold conditions as such. In fact, as Lift is directly proportional to density (L $\propto$ $\rho$), helicopters have better performance in cold weather (as air density is higher) and rotors produce more lift. Engine power is also usually increased. It is in hot-high conditions that helicopter lift production is critically affected.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'm adding this as the question has been cleaned up and changed a bit (effect of temperature in helicopter performance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature does affect the performance of the helicopter, as the density varies with temperature. The performance of the helicopter depends on three main atmospheric parameters (assuming all other helicopter parameters are equal):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Density altitude (air density)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Gross weight&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Wind velocity (during takeoff, hovering, and landing) &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The lift produced by the Helicopter blades is given by, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$L \ = \ \frac{1}{2} C_{L} \rho  V^{2} S$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, in helicopters, $S$, the blade area, $V$, due to rotor speed are fixed. So, as the density varies (due to altitude or weather), the lift coefficient $C_{L}$ has to be adjusted by varying the angle of attack of the blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the density decreases (due to hotter temperature or higher altitude), the required angle of attack (for producing same lift) increases. However, the maximum angle is limited by the blade stall angle. The net result is that the helicopter's ability to hover (or fly) at a particular altitude (or weight) is reduced due to change in temperature.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the hover chart for CH-47D. It is obvious from the chart that the hover performance is &lt;em&gt;significantly improved&lt;/em&gt; as the temperatures fall, at least till 0$^{\circ}$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7NPmj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7NPmj.jpg&quot; alt=&quot;CH-47 Hover&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: globalsecurity.org&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-23T13:07:49.450" LastActivityDate="2015-10-23T13:07:49.450" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22311" PostTypeId="2" ParentId="22304" CreationDate="2015-10-23T12:20:39.817" Score="1" Body="&lt;p&gt;The new EASA LAPL licenses (A, S, etc.) are sub-ICAO level licenses, meaning that they do not conform to ICAO standards (required minimum training hours, for one). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since ICAO is normally the framework under which various countries accept each others' licenses, there is currently no recognition of LAPL outside of EASA member states.&lt;/p&gt;&#xA;" OwnerUserId="2176" LastActivityDate="2015-10-23T12:20:39.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22312" PostTypeId="2" ParentId="22297" CreationDate="2015-10-23T12:25:01.577" Score="5" Body="&lt;p&gt;The climb angle depends on a number of factors like the airspeed, desired rate of climb, ToW, T/W ratio, airfield location (density altitude) etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most commercial airliners, the typical climb angles are in the range of 15-20$^{\circ}$, while a few aircraft exceed these limits. (Added in response to @Jon Story's Comment)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following figure shows the potential climb angles of Boeing airliners:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7NyWY.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7NyWY.gif&quot; alt=&quot;Boeing climb angle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_02_09/pdfs/AERO_Q209_article04.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing AERO magazine&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note  that the actual values will be different depending on various conditions as already noted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for GA aircraft, the typical climb angles will be in the range of 5-6$^{\circ}$ at sea level and decreasing with altitude, with other conditions being equal.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-23T16:31:16.333" LastActivityDate="2015-10-23T16:31:16.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22313" PostTypeId="1" AcceptedAnswerId="22314" CreationDate="2015-10-23T13:02:26.583" Score="29" ViewCount="5448" Body="&lt;p&gt;A jet engine is composed of fast moving pieces. Those pieces are moving into an airmass different form the ambient airmass the aircraft is flying into.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbine pieces are spinning quite fast, thus its blade tips may be moving at a supersonic speed. But, the airmass may also be spinning modifying the speed of the blades into the airmass. Moreover, the temperature of the air at this stage &lt;a href=&quot;https://en.wikipedia.org/wiki/Sound_speed_gradient&quot;&gt;may modify the speed of sound&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first stage of compressor is spinning at a much familiar air temperature and pressure, thus it may be easier to find if those compressor's blades' tips are moving faster than the speed of sound. But pressure (and thus temperature) is not the same before and after each compressor stage. It may be hard to define the speed of sound for this airmass going through the compressor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the airmass inside a jet-engine is different from the ambient airmass, are there any moving piece inside a jet-engine whose velocity (frame of reference: the airmass in which it is moving) is greater than the speed of sound?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2018-02-09T17:04:58.303" Title="Are the fastest moving pieces of a jet engine supersonic?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22314" PostTypeId="2" ParentId="22313" CreationDate="2015-10-23T13:12:59.273" Score="32" Body="&lt;p&gt;Yes, the tips of the fan blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at an example: The &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE-90&lt;/a&gt; has a &lt;a href=&quot;http://web.stanford.edu/~cantwell/AA283_Course_Material/GE90_Engine_Data.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;fan diameter&lt;/a&gt; of 3124&amp;nbsp;mm and a maximum rotational speed of 2475&amp;nbsp;RPM. Their circumferential velocity is d·π·41.25 = 405&amp;nbsp;m/s or Mach&amp;nbsp;1.19 at sea level and ISO atmosphere. Now you need to add the flow speed of the air, but this calculation alone should be sufficient to prove the point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inner part of the fan and all the compressor stages belonging to the core engine experience flow at subsonic speed, even if the whole engine is flying at &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=5%7C0.1459#9222&quot;&gt;supersonic speed&lt;/a&gt; (see picture below). To make ignition as complete as possible, the flow speed is &lt;a href=&quot;https://aviation.stackexchange.com/questions/11949/how-is-combustion-flame-maintained-in-the-combustion-chamber-after-igniters-are/11964?s=3%7C0.0621#11964&quot;&gt;continuously reduced&lt;/a&gt; the closer you move to the fuel injectors. Since the air is heated in the combustion chamber, the hotter gas has a higher speed of sound, and all the flow through the turbine is subsonic, too. This includes the low-pressure turbine. Even the 1,600&amp;nbsp;ft/s shown below at the turbine is subsonic, because at 1100°C the speed of sound in air is &lt;a href=&quot;http://www.wolframalpha.com/input/?i=speed%20of%20sound%20in%20air%20at%201100%C2%B0C&quot; rel=&quot;nofollow noreferrer&quot;&gt;720&amp;nbsp;m/s&lt;/a&gt; or 2,362&amp;nbsp;ft/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eLcXa.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eLcXa.jpg&quot; alt=&quot;Jet engine parameters&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overview of parameters in a typical jet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only in the rear part of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use/9666#9666&quot;&gt;convergent-divergent nozzle&lt;/a&gt; with reheat switched on will supersonic flow again be attained. This is exactly aft of the narrowest section, called the throat, where airspeed is equal to the speed of sound, and the petals of the nozzle are the only moving parts here. And they move rather slowly.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-02-09T17:04:58.303" LastActivityDate="2018-02-09T17:04:58.303" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22315" PostTypeId="2" ParentId="22313" CreationDate="2015-10-23T13:35:44.710" Score="16" Body="&lt;p&gt;In a turbofan engine, the fastest moving parts are usually the bypass fan tips. This is because at the same rotational speeds, the outer tips are at more distance and have higher linear velocities. In some engines, the tips reach supersonic speeds, usually at high thrust conditions. This is the reason for having a swept blade (like swept wing) in high bypass turbofans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7ZMV5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7ZMV5.jpg&quot; alt=&quot;Swept fan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: sheffield.ac.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of turbine blades (and to a lesser extent, compressors), the local temperature is high (due to combustion and compression); this increases the speed of sound (as it is proportional to $\sqrt{T}$ for an ideal gas). Due to this effect, the local flow is subsonic. Also, the blade size is very small compared to the bypass fan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next part where the flow goes supersonic is the divergent section of the convergent-divergent nozzle used in military jets (Note that there are no moving parts here).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-23T13:46:18.563" LastActivityDate="2015-10-23T13:46:18.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22316" PostTypeId="1" AcceptedAnswerId="22317" CreationDate="2015-10-23T13:46:39.097" Score="26" ViewCount="28266" Body="&lt;p&gt;It seems that the tips of the fan of a turbofan engine can and do break the sound barrier:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The GE-90 has a fan diameter of 3124 mm and a rotational speed of 3475 RPM. Their circumferential velocity is d·π·57.917 = 568 m/s or Mach 1.67 at sea level and ISO atmosphere.&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/22314/5517&quot;&gt;Peter Kämpf&lt;/a&gt;'s answer&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While, on a propeller driven aircraft, it seems that having the prop tips exceed the speed of sound is a bad thing - &lt;a href=&quot;https://aviation.stackexchange.com/questions/18789/can-turboprop-blades-break-the-sound-barrier&quot;&gt;Can turboprop blades break the sound barrier?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it that exceeding the speed of sound is acceptable in one situation but not the other?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2018-02-09T23:58:29.443" Title="Why do turbofan blade tips exceed the speed of sound while prop tips should not?" Tags="&lt;jet-engine&gt;&lt;propeller&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22317" PostTypeId="2" ParentId="22316" CreationDate="2015-10-23T14:11:31.410" Score="27" Body="&lt;h2&gt;Short answer:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Turbofans need supersonic speed at the fan blade tips to create their high thrust.&lt;/li&gt;&#xA;&lt;li&gt;Turbofans can tolerate supersonic speeds because the intake creates constant flow conditions irrespective of flight speed.&lt;/li&gt;&#xA;&lt;li&gt;Efficiency for propellers and fan blades is highest at subsonic flow conditions.&lt;/li&gt;&#xA;&lt;li&gt;Propellers can turn at supersonic speeds, but since flow conditions are less controlled, the penalty for doing so is much higher than the penalty for a fan.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Explanation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It is a bad thing to have supersonic fan blade tips, just like supersonic propeller tips are best avoided. But in turbofans it is a price worth paying, because the faster tip velocity means higher dynamic pressure, and the pressure difference between both sides of the fan blade grows with the square of their velocity. This makes the high thrust levels of modern turbofans possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tpaZ1.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tpaZ1.png&quot; alt=&quot;Propeller efficiency over speed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller efficiency over speed (picture &lt;a href=&quot;http://www.enginehistory.org/GasTurbines/Allison/XF-84/XF-84.shtml&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The plot for fan blades would look not much different. The very thin, uncambered airfoil of a supersonic propeller and the added wave drag lower the maximum efficiency, but hold efficiency up into supersonic air speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the propeller on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/21683/did-the-xf-84h-thunderscreech-really-cause-900-sonic-booms-per-minute/21700?s=1%7C0.1966#21700&quot;&gt;XF-84H Thunderscreech&lt;/a&gt; did move at supersonic speed. There is nothing inherent in propellers which prevents their tips from moving faster than the speed of sound. On the other hand, the big diameter of a prop requires proportionally more torque to keep the prop rotating against the drag from the supersonic tips. Thus, a fan engine requires less torque per blade to reach supersonic tip speeds on the fan blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11884/do-nacelles-around-aircraft-engines-help-in-reducing-the-engine-sound/11891#11891&quot;&gt;shroud of a turbofan engine helps a lot&lt;/a&gt; to make the noise from supersonic tips manageable. The XF-84H's noise made people literally sick. But there is more to it: @FreeMan encouraged me with his comment to dive a little deeper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A supersonic propeller will work well when the direction of flow at every station along the propeller blade is about equal to the local airfoil chord. Since the blade is uncambered, this means that the change in local flow direction at the leading edge can be minimized to the amount which is required to create the desired thrust. But to be able to fulfill this condition you need to match your propeller speed to the flight speed &lt;strong&gt;and&lt;/strong&gt; twist distribution. Also, the angle of attack must be compensated for by sviveling this propeller axis into the direction of flight. It will have no &lt;a href=&quot;https://aviation.stackexchange.com/questions/312/whats-p-factor-and-why-does-it-occur&quot;&gt;p-factor&lt;/a&gt;, but can run at only one speed for a given flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrast this with a turbofan: The intake makes sure that the flow speed and direction at the face of the fan is the same no matter what the flight speed is. This is done by the pressure field in and around the intake which &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;will spill excess air overboard at high speed or suck extra air&lt;/a&gt; in from the sides at low speed. In the fan you can indeed match the local angle of incidence to the airspeed so the fan will work well over its design range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, a fully subsonic fan would be more efficient. But then the diameter would need to be as large as that of big turboprop engines, and the shroud would become impossibly heavy and produce too much drag. The high dynamic pressure on the fan blades is needed to produce the thrust with the relatively small diameter of a turbofan.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-02-09T23:58:29.443" LastActivityDate="2018-02-09T23:58:29.443" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="22318" PostTypeId="2" ParentId="8177" CreationDate="2015-10-23T15:04:26.763" Score="4" Body="&lt;p&gt;Another reason helicopter pilots sit on the right is because the cyclic is held in the right hand, and the collective in the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its safer for the pilot to take his left hand off the collective to operate the radios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qf7Q5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qf7Q5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-10-23T15:04:26.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22319" PostTypeId="2" ParentId="22316" CreationDate="2015-10-23T15:19:32.750" Score="13" Body="&lt;p&gt;Propeller tips can and sometimes do go supersonic (like &lt;a href=&quot;https://en.wikipedia.org/wiki/Republic_XF-84H&quot;&gt;XF-84H&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-95&quot;&gt;Tu-95&lt;/a&gt;). However, while it is tolerated in case of turbofan (some measures like swept blades and low speed fans are used in turbofans to counter this), it is not so in case of propellers for a few reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;As the supersonic speeds are approached (or exceeded locally), shock waves form over sections of the propeller blades- This significantly reduces the propeller efficiency while at the same time causes increased loads on the blade. This causes a problem- For supersonic speeds, the blades have to be extremely thin, while the loads require the blades to be thicker. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The drag due to the (tip) shock waves increases the required engine power tremendously. For example, the Tu-95's engines had to be uprated from 12000 shp in the prototypes to 15000 in production units to reach the required speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another main reason is sound- XF-45 was &lt;a href=&quot;http://www.abc.net.au/science/articles/2003/09/11/934718.htm?site=science/greatmomentsinscience&quot;&gt;so loud that it caused seizures&lt;/a&gt;. In case of turbofans, the bypass fan is covered, which mitigates the noise issues somewhat.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-23T15:19:32.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22321" PostTypeId="2" ParentId="22316" CreationDate="2015-10-23T16:20:10.387" Score="8" Body="&lt;p&gt;&lt;em&gt;Why is it that exceeding the speed of sound is acceptable in one situation but not the other?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because lift (or thrust of the propeller which is a wing that rotates) at supersonic speeds decreases while compression is not influenced. The air that strikes the blades of a compressor has no other way to go but to pass through it and feed the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a propeller at supersonic speeds the air instead of flowing around the blades forms V waves, a phenomenon that increases drag and reduces lift (thrust). &lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-23T16:51:31.647" LastActivityDate="2015-10-23T16:51:31.647" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22322" PostTypeId="2" ParentId="9653" CreationDate="2015-10-23T16:35:30.317" Score="0" Body="&lt;p&gt;One thing so far not mentioned or considered is that as the jet pipe nozzle changes area the static pressure within it will change. Consequently the differential pressure across the L.P. turbine (assuming a twin or triple spool engine) will also change. This speeds up or slows down the L.P. compressor.&lt;/p&gt;&#xA;" OwnerUserId="11967" LastActivityDate="2015-10-23T16:35:30.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22325" PostTypeId="1" AcceptedAnswerId="22326" CreationDate="2015-10-23T17:57:32.787" Score="7" ViewCount="2433" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Type_rating&quot;&gt;Wikipedia page&lt;/a&gt; on type ratings says that most single-engine piston aircraft are covered under a single class rating but under JAA regulations the Piper Malibu requires its own type rating. (I'm unsure as to whether these regulations still apply or if the JAA even still exists.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is different about the Malibu that would require its own type rating? And do other regulatory agencies (FAA, EASA) require this?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-23T23:52:22.043" Title="Why does the Piper Malibu require a type rating?" Tags="&lt;type-ratings&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22326" PostTypeId="2" ParentId="22325" CreationDate="2015-10-23T18:45:05.077" Score="6" Body="&lt;p&gt;Here in the US the FAA can impose a type rating on any aircraft it likes (see part 3 below). Generally speaking type ratings are either for big planes or planes that may require additional training for safety reasons.&lt;/p&gt;&#xA;&lt;p&gt;You can find the full regulations relating to US type ratings in the FAR under&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=40760189a03dfea0b501608f33820a45&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.1.2&amp;amp;idno=14#se14.2.61_131&quot; rel=&quot;noreferrer&quot;&gt;§61.31   Type rating requirements, additional training, and authorization requirements.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;but basically,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Type ratings required. A person who acts as a pilot in command of any of the following aircraft must hold a type rating for that aircraft:&lt;/p&gt;&#xA;&lt;p&gt;(1) Large aircraft (except lighter-than-air).&lt;/p&gt;&#xA;&lt;p&gt;(2) Turbojet-powered airplanes.&lt;/p&gt;&#xA;&lt;p&gt;(3) Other aircraft specified by the Administrator through aircraft type certificate procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In specific relation to the Malibu the US FAA does not require a type rating, you can find a &lt;a href=&quot;http://registry.faa.gov/TypeRatings/&quot; rel=&quot;noreferrer&quot;&gt;full list of aircraft that require a type rating here&lt;/a&gt;. However it should be noted that to fly Pipers &lt;a href=&quot;http://www.piper.com/aircraft/m-class/m600/&quot; rel=&quot;noreferrer&quot;&gt;M600&lt;/a&gt; and &lt;a href=&quot;http://www.piper.com/aircraft/m-class/m500/&quot; rel=&quot;noreferrer&quot;&gt;M500&lt;/a&gt; Malibu variants, both of which have a service ceiling over 25,000Ft you would need a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Advanced-Flight-Training/Ratings-and-Endorsements/Other-Ratings&quot; rel=&quot;noreferrer&quot;&gt;High Altitude Endorsement&lt;/a&gt; (along with all the other endorsements for a high performance plane like that).&lt;/p&gt;&#xA;&lt;p&gt;The JAA may require such a rating due to the pressurization system in the plane.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-23T19:05:57.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22329" PostTypeId="2" ParentId="22316" CreationDate="2015-10-23T22:26:17.490" Score="8" Body="&lt;p&gt;The most important difference is that the fan blades are running inside a casing, and propellers operate in free air. Most of the noise and energy loss comes from the vortices shed from the tips of the prop blades. The fan case prevents those vortices from forming, except for the small amount of air leakage between the blade tips and the casing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is inevitably a small clearance gap between blades and casing, for example because the &lt;em&gt;external&lt;/em&gt; aerodynamic forces on the casing may deform it into non-circular shape in some flight conditions, but the maximum gap around a 3000mm diameter fan would typically be less than 5mm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ducted propellers are used in small sizes, but the weight penalty of a large duct that is strong enough to survive conditions like birdstrike (and the collateral damage from bent or broken prop blades) would be prohibitive for large props.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2015-10-23T22:26:17.490" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22330" PostTypeId="2" ParentId="22325" CreationDate="2015-10-23T23:52:22.043" Score="2" Body="&lt;p&gt;Aircraft such as the Piper Malibu, TBM family and the likes  can only be flown under EASA rules (that superseded JAA ten years ago) with an endorsement named High Performance Aircraft. No need for a type rating.&#xA;This endorsement also covers EFIS, variable pitch, retractable undercarriage endorsements.&lt;/p&gt;&#xA;" OwnerUserId="11973" LastActivityDate="2015-10-23T23:52:22.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22331" PostTypeId="1" AcceptedAnswerId="22332" CreationDate="2015-10-24T00:53:59.253" Score="1" ViewCount="596" Body="&lt;p&gt;I'm from Croatia and I'm intersted in becoming a pilot, but however, I'm not going to the college deisgned for that (I'm studying IT, not aeronautics).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, I contacted Croatia Airlines and they told me that I needn't have an aeronautics college degree, but I do need these qualifications to apply for the First Officer (Co-pilot) position:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;hold a valid CPL (A)&lt;/li&gt;&#xA;&lt;li&gt;hold a valid multi-engine instrument rating (airplane) (ME-IR(A))&lt;/li&gt;&#xA;&lt;li&gt;successfuly completed a Multi Crew Coordination (MCC) Course&lt;/li&gt;&#xA;&lt;li&gt;hold a Category 1 Medical Certificate&lt;/li&gt;&#xA;&lt;li&gt;hold a valid Associate Degree&lt;/li&gt;&#xA;&lt;li&gt;hold at least English Proficiency Level 4&lt;/li&gt;&#xA;&lt;li&gt;hold a certificate of passed ATPL (A) theoretical knowledge examinations according FCL.515&lt;/li&gt;&#xA;&lt;li&gt;be minimum of 21 years of age &lt;/li&gt;&#xA;&lt;li&gt;total flight time:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ab-initio pilots: at least 250 hours total time, to include 100 hours as pilot-in-command of airplanes&lt;/li&gt;&#xA;&lt;li&gt;Pilots with valid type rating: a minimum of 500 hours on respective type&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, I have a few questions. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Does someone know where I can get my licences for being an civil pilot in Croatia? &lt;/li&gt;&#xA;&lt;li&gt;About theoretical knowledge (physics, mathematics):&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Could I watch MIT OpenCourseware on that (and if I do, should I watch &lt;a href=&quot;http://catalog.mit.edu/degree-charts/aerospace-engineering-course-16/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; or &lt;a href=&quot;http://catalog.mit.edu/degree-charts/engineering-aeronautics-astronautics-course-16-eng/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt;? &lt;/li&gt;&#xA;&lt;li&gt;I stumbled upon Flying Academy website (can't post the link because I'm new here) and it says &quot;Sufficient level of knowledge of Mathematics and Physics&quot;. &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;What is sufficient and what would I have to learn?&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I know I have a lot of questions, but I would really like to become a pilot one day and I believe I am self-disciplined enough to learn on my own. Can someone show me the way?&lt;/p&gt;&#xA;" OwnerUserId="11974" LastEditorUserId="5517" LastEditDate="2015-10-26T12:48:22.497" LastActivityDate="2015-10-26T12:48:22.497" Title="What education is needed to become a civil pilot?" Tags="&lt;aerodynamics&gt;&lt;commercial-aviation&gt;&lt;aircraft-physics&gt;&lt;cpl&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22332" PostTypeId="2" ParentId="22331" CreationDate="2015-10-24T03:37:36.333" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;First, does someone know where I can get my licences for being an civil pilot in Croatia? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm afraid nobody here can help you with that: You will need to find a flight instructor or flight school in your area. (Google can probably help you locate candidate schools, and we have some general advice on &lt;a href=&quot;https://aviation.stackexchange.com/questions/14411/how-to-choose-a-flight-school&quot;&gt;selecting a school&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/9869/what-to-look-for-in-a-flight-instructor&quot;&gt;selecting an instructor&lt;/a&gt; that might help you narrow down your choices.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Second, about theoretical knowledge (physics, mathematics), could I watch MIT OpenCourseware on that (and if I do, should I watch this or this? I stumbled upon Flying Academy webiste (can't post the link because I'm new here) and it says &quot;Sufficient level of knowledge of Mathematics and Physics&quot;.&lt;br&gt;&#xA;  &lt;strong&gt;What is sufficient and what would I have to learn?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To begin flight training you don't need to know &lt;em&gt;anything&lt;/em&gt; about math or physics: Your initial training will be about manipulating the controls of an aircraft to make it do what you want it to do, and for the moment you don't care &lt;em&gt;how&lt;/em&gt; or &lt;em&gt;why&lt;/em&gt; it works, you just need to learn the physical technique of controlling an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point in your training you will learn the physics of flight - this is generally part of &quot;Ground School&quot; but your flight instructor may introduce the concepts to you as you approach lessons where they will be relevant.&lt;br&gt;&#xA;A basic understanding of the laws of motion and air pressure will be helpful, but everything you need to know can be found in the various &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA handbooks&lt;/a&gt; (the Pilot's Handbook of Aeronautical Knowledge, the Aeronautical Information Manual, and the Airplane Flying Handbook are good starting places - regulations will probably differ in Croatia, but the basics of flight will be the same, and are explained in fairly simple language in those books).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also need to be able to work basic flight planning calculations as you advance in your training, which means you will need some basic mathematical knowledge: The ability to add, subtract, multiply, divide, and do simple algebra will cover nearly everything you need to do as a pilot, and higher math is generally not necessary unless you start getting into the &lt;em&gt;Why&lt;/em&gt; of aerodynamic theory.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-24T03:37:36.333" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22333" PostTypeId="1" AcceptedAnswerId="22347" CreationDate="2015-10-24T09:58:36.320" Score="21" ViewCount="2263" Body="&lt;p&gt;What is this orange container for?&#xA;It reads &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flight kit wheel. Do not remove.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What's a &quot;flight kit wheel&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jGMSE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jGMSE.jpg&quot; alt=&quot;Orange container on ramp&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10076" LastEditorUserId="10076" LastEditDate="2017-11-02T11:07:26.260" LastActivityDate="2020-11-11T12:42:17.503" Title="What is this orange container labeled &quot;Flight kit wheel&quot;?" Tags="&lt;airliner&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22334" PostTypeId="1" AcceptedAnswerId="22335" CreationDate="2015-10-24T10:34:51.903" Score="11" ViewCount="3099" Body="&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/a/1498/3394&quot;&gt;answer&lt;/a&gt; provides pictures and drawing of implementation of both PAPI and VASI. In all pictures I found, I cannot figure if there is a rule to put those lights on the &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Jersey_Airport.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;right&lt;/a&gt;, on the &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Vasi-1.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;left&lt;/a&gt;, or on &lt;a href=&quot;http://www.airliners.net/photo/Swiftair/ATR-ATR-72-500-%28ATR-72-212A%29/1598858/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;both sides&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some rules to decide if the path indicator lights should be placed on the right or on the left side of the runway?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-25T11:11:05.483" Title="How to decide on which side of the runway the approach path indicator (VASI, PAPI) are placed?" Tags="&lt;airport-lighting&gt;&lt;papi&gt;&lt;vasi&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22335" PostTypeId="2" ParentId="22334" CreationDate="2015-10-24T11:58:57.320" Score="13" Body="&lt;p&gt;Path/slope visual indicators are usually located on the left side of the runway (as seen when approaching), but may be on the right side when impractical. Good reasons for moving the aid on the right side:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstacle clearance, terrain, intersecting runways or taxiways.&lt;/li&gt;&#xA;&lt;li&gt;Interference may occur on the left side, between PAPI lights and nearby lights. This is emphasized in FAA &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5340_30g.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 150/5340-30G - Design and Installation Details for Airport Visual Aids&lt;/a&gt;: &quot;&lt;em&gt;Because PAPI system is dependent upon the pilot seeing a red and/or white signal from the light units, care should be taken to assure that no other lights are located close enough to the system to interfere with the signal presentation.&lt;/em&gt;&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Installing them on both sides is beyond ICAO recommendations and FAA orders, but can be done:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For visibility improvement&lt;/li&gt;&#xA;&lt;li&gt;In order to give better roll guidance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some countries don't implement ICAO rules the same way, for instance in the UK, PAPI for governmental airports &quot;&lt;em&gt;may be provided on both sides of the runway&lt;/em&gt;&quot; (&lt;a href=&quot;https://www.caa.co.uk/docs/33/CAP637%20Visual%20Aids%20Handbook.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airports providing a visual guidance for &lt;a href=&quot;https://en.wikipedia.org/wiki/STOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;STOL&lt;/a&gt; operations. The PAPI associated with the steeper approach path may be located on the right side of the runway (&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/291.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8sZC2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8sZC2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;PAPI at the usual location, on the left side of the runway (&lt;a href=&quot;http://www.airwaysmuseum.com/PAPI.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Precision_approach_path_indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The international standard for PAPI is published by the International&#xA;  Civil Aviation Organisation (ICAO) in Aerodromes, Annex 14 to the&#xA;  Convention on International Civil Aviation, Volume 1, Chapter 5.&#xA;  National regulations generally adopt the standards and recommended&#xA;  practices published by ICAO.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.skybrary.aero/index.php/Visual_Approach_Slope_Indicator_Systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA JO 6850.2B - Visual Guidance Lighting Systems&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The basic PAPI configuration is described in chapter 1, section 2,&#xA;  paragraph 16, and is shown in figure 5-1. All lamphousing assemblies&#xA;  (LHA's) should be located on the left side of the runway, as viewed&#xA;  from the approach direction. However, where terrain, cross runways,&#xA;  or taxiways make this arrangement impractical, the light units may&#xA;  be located on the right side of the runway.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The VISUAL APPROACH SLOPE INDICATOR (VASI) system is no longer &#xA;  installed by the FAA as a new facility. Specific details and installation&#xA;  criteria have been moved to Appendix E to provide technical support for&#xA;  existing VASI equipment and facilities.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The basic VASI configurations are described in appendix D, section&#xA;  1, paragraph 1 and shown in figures 1, 2, 4, and 5. All boxes (or &#xA;  light units) of the two-box; four-box, and six-box configurations are&#xA;  located on the left side of the runway (as viewed from the approach &#xA;  direction). However, where terrain or cross runways, etc., make this&#xA;  impractical, they may be located on the right side of the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.globalair.com/airport/apt.runway.aspx?aptcode=IAD&quot; rel=&quot;nofollow noreferrer&quot;&gt;Washington Dulles Int'l Airport &lt;/a&gt; offer several location variations, chosen for practical reasons. There is a PAPI on the left side for runway 1C and &lt;a href=&quot;https://www.google.fr/maps/place/A%C3%A9roport+international+de+Washington-Dulles/@38.9575704,-77.4596524,1077a,20y,41.42t/data=!3m1!1e3!4m2!3m1!1s0x89b64740174eb057:0x8e01cb201080601d!6m1!1e1&quot; rel=&quot;nofollow noreferrer&quot;&gt;on the right side for 19C&lt;/a&gt;, but a reverse scheme is used for 1R/19L, and 1L/19R is just standard:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BFJ1R.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BFJ1R.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-10-25T11:11:05.483" LastActivityDate="2015-10-25T11:11:05.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22336" PostTypeId="2" ParentId="22334" CreationDate="2015-10-24T12:26:57.607" Score="6" Body="&lt;p&gt;In general, the PAPI is located on the left side of the runway. However, depending upon the runway / taxiway configuration, the PAPI can be located on the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the &lt;a href=&quot;http://www.icao.int/safety/implementation/library/manual%20aerodrome%20stds.pdf&quot;&gt;Aerodrome Design and Operations&lt;/a&gt; based on ICAO Annex 14 to the Convention on International Civil Aviation, the international standard for PAPI (and other runway lighting systems),&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The PAPI system shall consist of a wing bar of 4 sharp transition multi-lamp (or paired single lamp) units equally spaced. The system shall be located on the left side of the runway unless it is physically impracticable to do so.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Most of the regulatory bodies follow the ICAO recommendations. As for PAPI on both sides of the runway, maybe they are there for improved visibility/redundancy.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-24T12:26:57.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22338" PostTypeId="1" AcceptedAnswerId="22353" CreationDate="2015-10-24T17:37:00.770" Score="16" ViewCount="46859" Body="&lt;p&gt;When Patricia was making landfall yesterday I opened up Flight Radar 24 to see if there were any planes flying around or near it.  As I had expected, there were a couple of storm watching planes near the hurricane, but what surprised me is that there were some commercial flights that seemed to be going over portions of the hurricane...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, I'm curious, can commercial aircraft go high enough to simply fly over a hurricane, assuming they take off and land at airports that are not effected by the storm?  Or perhaps they can only safely fly over the fringes and need to stay away from the eye?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, can airliners fly over hurricanes, and if so can they fly over all of it, or just parts?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="595" LastEditDate="2015-10-24T18:00:13.497" LastActivityDate="2017-09-07T18:33:20.657" Title="Can commercial airliners fly over hurricanes?" Tags="&lt;commercial-aviation&gt;&lt;weather&gt;&lt;high-altitude&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22339" PostTypeId="2" ParentId="22338" CreationDate="2015-10-24T18:11:41.520" Score="4" Body="&lt;p&gt;A hurricane can reach up into the tropopause at 50,000+ feet, making it impossible for a modern airliner to overfly it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you could overfly it, you're in a difficult situation where if anything goes wrong (i.e., requiring a descent), your options are much more limited since hurricanes are so large in area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are circumstances where you would fly near the &lt;em&gt;edge&lt;/em&gt; of the hurricane in order to take off or land before the main part hits.&lt;/p&gt;&#xA;" OwnerUserId="11520" LastEditorUserId="11520" LastEditDate="2015-10-24T18:16:51.847" LastActivityDate="2015-10-24T18:16:51.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22340" PostTypeId="1" AcceptedAnswerId="22342" CreationDate="2015-10-24T19:12:05.083" Score="6" ViewCount="588" Body="&lt;p&gt;What methods are used to achieve that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to my search :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For old planes they use a plumb bob and measuring tools.&lt;/li&gt;&#xA;&lt;li&gt;On new and big planes, the process is computerized. Built-In Electronic Weighing like the Boeing 777&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="11981" LastEditorUserId="8730" LastEditDate="2015-10-25T19:00:18.100" LastActivityDate="2019-07-14T21:12:53.390" Title="How much time does it take to calculate the leveling and weighing of big and small aircraft?" Tags="&lt;weight-and-balance&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22341" PostTypeId="2" ParentId="22338" CreationDate="2015-10-24T20:24:36.950" Score="2" Body="&lt;p&gt;&lt;em&gt;Can commercial airliners fly over hurricanes?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can fly through the top (or even the base) of the hurricane in an emergency situation and nothing will happen, see&#xA;&lt;a href=&quot;https://www.youtube.com/watch?v=a-SnxC-BkPo&quot; rel=&quot;nofollow&quot;&gt;Flying through a hurricane (YouTube)&lt;/a&gt;, but it is not preferred to expose the plane to such vibrations if better options, like going around the hurricane, are available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The critical point is crossing the edge of the hurricane eye. However, an airplane can pass through that zone of high winds in minutes. &lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="1696" LastEditDate="2015-10-25T00:32:46.727" LastActivityDate="2015-10-25T00:32:46.727" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22342" PostTypeId="2" ParentId="22340" CreationDate="2015-10-24T20:25:47.370" Score="13" Body="&lt;p&gt;Having recently weighed my plane I can tell you what's involved for determining the Basic Empty Weight for a small aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;The aircraft equipment list is checked and updated.&lt;/strong&gt;&lt;br&gt;&#xA;This is kind of important as the equipment list includes the weight and arm of everything installed on the airframe. If this list is not accurate future weight and balance updates based on adding/removing equipment using the weights and arms on that list will be incorrect, and your computed weight and balance will start to diverge from the &lt;em&gt;actual&lt;/em&gt; weight and balance until the plane is weighed again.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The aircraft interior is cleaned to &quot;factory empty&quot; status.&lt;/strong&gt;&lt;br&gt;&#xA;Pens, pencils, 3-year-old charts, note pads, and other things &lt;em&gt;not&lt;/em&gt; on the equipment list are all removed, and things like tow bars are placed in their appropriate location/holder.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The aircraft is serviced with &quot;fluids&quot; per the manufacturer's procedures for weighing.&lt;/strong&gt;&lt;br&gt;&#xA;For most small planes this means de-fueled, full engine oil, &amp;amp; full hydraulic/brake fluid.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The shop sets up and zeros their scales.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;You tow/push the aircraft onto the scales.&lt;/strong&gt;&lt;br&gt;&#xA;(Or lift it on jack stands with integrated scales designed for this purpose.)&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The aircraft is leveled on the scales.&lt;/strong&gt;&lt;br&gt;&#xA;The plane must be leveled laterally (left-to-right) and longitudinally (nose-to-tail), otherwise the computations made later will be inaccurate.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The numbers on the scales are recorded.&lt;/strong&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;The Weight and Balance is determined:&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Add the numbers from all scales used. This is your Empty Weight.&lt;/li&gt;&#xA;&lt;li&gt;You do some math on the scale numbers to determine the Center of Gravity.&lt;br&gt;&#xA;(Since you know the station/arm of each scale you can figure out the CG based on the weights) &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As Terry mentioned, setting up took more time than the actual weighing and calculations. In my case I spent about a day straightening out the equipment list, and the shop that did the weighing spent about 20 minutes verifying that I hadn't missed anything. Defueling the aircraft adds a significant amount of time to the process as well. Moving the plane onto the scales and leveling it took approximately 15 minutes, and doing the math took maybe another 5 minutes. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On larger aircraft &lt;a href=&quot;https://www.youtube.com/watch?v=MZ58YgKSFBI&quot;&gt;the same general process can be used with larger scales (or jacks)&lt;/a&gt; - load cells integrated into a taxiway or ramp area are another option for doing this.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if aircraft that can determine their operating weight (by load cells installed in the gear assembly) can also determine their own empty weight - I know the weighing report I received includes calibration information for the scales used, so presumably weighing a large aircraft using its built-in load cells would require those cells to be properly (traceably) calibrated prior to using them for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-24T20:25:47.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22343" PostTypeId="1" CreationDate="2015-10-24T21:47:19.010" Score="-4" ViewCount="356" Body="&lt;p&gt;According to my search:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Almost 12% of all aircraft accident reports cite a maintenance factor.&#xA;&lt;a href=&quot;https://www.maintenanceassistant.com/blog/poor-maintenance-cost-lives/&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="11981" LastEditorUserId="11981" LastEditDate="2015-10-28T06:09:51.900" LastActivityDate="2015-10-28T06:09:51.900" Title="which part of aircraft maintenance or inspection that could be automated to avoid maintenance error?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-10-24T23:44:00.807" ContentLicense="CC BY-SA 3.0" />
  <row Id="22344" PostTypeId="2" ParentId="9353" CreationDate="2015-10-24T22:31:50.663" Score="3" Body="&lt;p&gt;From my reading of this (&lt;a href=&quot;https://www.caa.co.uk/default.aspx?catid=49&amp;amp;pagetype=90&amp;amp;pageid=13879&quot; rel=&quot;nofollow&quot;&gt;https://www.caa.co.uk/default.aspx?catid=49&amp;amp;pagetype=90&amp;amp;pageid=13879&lt;/a&gt;), colour-blindness means you can't get a class 1 (commercial) medical, but can get a class 2 (private) with a restriction that bars you from night flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm neither a medic nor colour-blind though so I'd definitely recommend you get in touch with an AME (authorised medical examiner, who you'll need to see anyway before going solo) to check before you pay for much training!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Costs for a full PPL... depends a lot on area, school, airport etc but you might be looking at something approaching £10k. That's £150/hr for a cheap plane, £30/hr for an instructor, and let's call it 50 hours (45 minimum + the exam + some leeway) to get 9k. Then 9 ground exams @ £25 = 225, and new study guides which are about £120 (I got mine 2nd hand from eBay for about £40 but the syllabus has changed; I've no idea how much). Initial medical exam is around £200, skills test around £170, CAA admin another £180. Oh, and your flying school may want a membership fee, let's say £100/year. That's, what, £9975? I've taken a few shortcuts (e.g. maybe you won't need 50hrs and I've ignored cheap stuff like a logbook, kneeboard, ruler marked in nm) but £10k seems reasonable to me as a rough estimate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also ignored landing fees. My local fees were included but you'll need a few land-aways (at least 4?) at £10-20 each. Beware of the &quot;local fees&quot; thing... I've spoken to people who found much cheaper lessons elsewhere, but they didn't include any landing fees. I reckon I booked at least 100 landings/touch&amp;amp;gos during my PPL, which would have made that &quot;cheap&quot; rate a lot less appealing.&lt;/p&gt;&#xA;" OwnerUserId="11809" LastActivityDate="2015-10-24T22:31:50.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22345" PostTypeId="2" ParentId="22343" CreationDate="2015-10-24T22:51:03.230" Score="1" Body="&lt;p&gt;1) An automated test will only test the things it is designed for. A visual inspection is an opportunity for a pilot to spot unexpected problems or problems not covered elsewhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) &lt;em&gt;'it is not accurate'&lt;/em&gt; - define 'accurate', and explain how you come to this conclusion.&lt;/p&gt;&#xA;" OwnerDisplayName="user11933" LastActivityDate="2015-10-24T22:51:03.230" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22346" PostTypeId="1" AcceptedAnswerId="22357" CreationDate="2015-10-24T22:56:02.337" Score="7" ViewCount="3684" Body="&lt;p&gt;There exist several aircraft - especially carrier-based ones - that have folding wings, to save space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this structure strong, taking into account the considerable amount of force on the hinge-based system (is it?) from the wing loading? How are they prevented from just snapping mid-air?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zTGlu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zTGlu.jpg&quot; alt=&quot;Super Hornet (from Wikpedia)&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt; Photo by Petty Officer 3rd Class Jason Johnston, U.S. Navy: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Super_Hornet_on_flight_deck.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Public Domain&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same question regarding helicopter rotors too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/d/d5/V-22_Osprey_wing_rotated.jpg?1445727886365&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/d/d5/V-22_Osprey_wing_rotated.jpg?1445727886365&quot; alt=&quot;Osprey (from Wikpedia)&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt; Photo by Lt. Col. Kevin Gross: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:V-22_Osprey_wing_rotated.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Public Domain&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="22726" LastEditDate="2019-02-23T05:25:54.540" LastActivityDate="2019-02-23T05:25:54.540" Title="How are folding wings managed?" Tags="&lt;wing&gt;&lt;aircraft-structures&gt;&lt;rotorcraft&gt;&lt;folding-wings&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22347" PostTypeId="2" ParentId="22333" CreationDate="2015-10-24T23:37:02.497" Score="27" Body="&lt;h3&gt;Short answer&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Corsair_International&quot; rel=&quot;nofollow noreferrer&quot;&gt;Corsair&lt;/a&gt; is a small airline, with a limited number of aircraft, serving airports in remote islands from Paris. For their economical survival their aircraft must keep a high operational ratio. However:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The airline may not have a maintenance facility at destination, either a owned facility or an agreement for maintenance services from another company locally based.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The facility may not have a satisfactory stock of spare parts for their aircraft or the required tools, and no possibility to obtain them in a very short time, even from their main base.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;A common solution is to bring parts aboard, in particular &lt;a href=&quot;https://www.skybrary.aero/index.php/Minimum_Equipment_List_(MEL)&quot; rel=&quot;nofollow noreferrer&quot;&gt;MEL&lt;/a&gt; components. It's a balance between the cost to carry the container and the cost of extra wait time (better said by FreeMan in a comment below: &lt;em&gt;The weight penalty is much lower than the wait penalty&lt;/em&gt;.)&lt;/p&gt;&#xA;&lt;p&gt;These containers marked &lt;em&gt;Flight kit&lt;/em&gt;, &lt;em&gt;Fly away kit&lt;/em&gt; (FAK), &lt;em&gt;Do not unload&lt;/em&gt;, &lt;em&gt;Do not offload&lt;/em&gt;, etc, contain components or tools intended to remain on board and be used at the next stopover in case of necessity.&lt;/p&gt;&#xA;&lt;p&gt;It's relatively common to see FAK for spare wheels. One of the reasons is when the crew executes a &lt;a href=&quot;https://www.youtube.com/watch?v=_g6UswiRCF0&amp;amp;t=0m55s&quot; rel=&quot;nofollow noreferrer&quot;&gt;rejected take-off&lt;/a&gt; just prior to &lt;a href=&quot;https://www.skybrary.aero/index.php/V1&quot; rel=&quot;nofollow noreferrer&quot;&gt;V1 speed&lt;/a&gt; on a large aircraft, brakes are subject to intense heating propagated to the wheels. Tires inflated with nitrogen at about 1,300 kPa (that's about 13 bars or 200 psi) could blow out beyond a certain temperature, causing damages/injuries. To prevent such explosion, wheels are fitted with &lt;a href=&quot;https://www.skybrary.aero/index.php/Fusible_Plug&quot; rel=&quot;nofollow noreferrer&quot;&gt;fusible plugs&lt;/a&gt; melting to allow tires to deflate safely.&lt;/p&gt;&#xA;&lt;p&gt;After such event, the plugs (and possibly the tire) have to be replaced. A common option is to change the whole wheel and perform inspection and repairs later. The kit contains the necessary tooling and parts for this replacement. This might take 30 minutes or so.&lt;/p&gt;&#xA;&lt;p&gt;As FreeMan also mentions, sometimes the mechanic who is going to replace the wheel is onboard. That was the case (at the time the photo was shot) for Corsair for certain destinations where there is no permanent maintenance team at the stopover.&lt;/p&gt;&#xA;&lt;h3&gt;Corsair, a small airline serving remote locations&lt;/h3&gt;&#xA;&lt;p&gt;And actually Corsair is a small French airline based at Paris-Orly (LFPO), which has a taste of holidays. &lt;a href=&quot;http://www.airfleets.net/flottecie/Corsair.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Their 5 aircraft&lt;/a&gt; take people from Paris to beautiful beaches on islands where airports don't have large maintenance facilities (&lt;a href=&quot;https://en.wikipedia.org/wiki/Martinique_Aim%C3%A9_C%C3%A9saire_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fort-de-France&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Pointe-%C3%A0-Pitre_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pointe-à-Pitre&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Roland_Garros_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;La Réunion&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Saint_Martin_(island)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saint Martin&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Palma_de_Mallorca&quot; rel=&quot;nofollow noreferrer&quot;&gt;Palma&lt;/a&gt; ...)&lt;/p&gt;&#xA;&lt;p&gt;For a long time Corsair used Boeing 747 Classic, meaning also less common spare parts.&lt;/p&gt;&#xA;&lt;p&gt;In such a small airline, when an aircraft is grounded the schedule of the others is indeed disrupted, the shorter, the better.&lt;/p&gt;&#xA;&lt;h3&gt;Flight kit&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aOZDi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aOZDi.jpg&quot; alt=&quot;Linde forklift loading a flight kit&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Loading a flight kit, source &lt;a href=&quot;https://www.motrac.be/fr-be/linde/produits/chariots-elevateurs/chariots-elevateurs-electriques/linde_e35-e50&quot; rel=&quot;nofollow noreferrer&quot;&gt;Linde&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/upwyC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/upwyC.jpg&quot; alt=&quot;Flight kit, Air France, A380&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Flight kit, Air France (translates to &amp;quot;&lt;em&gt;Fly away kit, do not unload&lt;/em&gt;&amp;quot;). Photo by &lt;a href=&quot;https://www.flickr.com/photos/a380spotter/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A380spotter&lt;/a&gt; at &lt;a href=&quot;https://www.flickr.com/photos/a380spotter/4852471844/in/photostream/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flickr&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9aY82.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9aY82.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Flight kit wheels in cargo hold (Malawi elections inspection). &lt;a href=&quot;https://www.facebook.com/mijmw/photos/a.2129965640357977/3139583666062831/?type=3&amp;amp;theater&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;h3&gt;Secured content&lt;/h3&gt;&#xA;&lt;p&gt;Parts in the container are secured to prevent them from moving.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3ef0v.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3ef0v.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;AKN FSK container for Air France (&lt;a href=&quot;http://vrr-aviation.com/projects/akn-fsk-container-2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WrrcF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WrrcF.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://vrr-aviation.com/news/customising-flight-spare-kits-with-detail-and-care&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;See also: &lt;a href=&quot;https://aviation.stackexchange.com/questions/21396/do-any-aircraft-carry-spare-parts-for-making-repairs&quot;&gt;Do any aircraft carry spare parts for making repairs?&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;Corsair&lt;/em&gt;, formerly &lt;em&gt;Corse Air&lt;/em&gt;, comes from &lt;a href=&quot;https://en.wikipedia.org/wiki/Corsica&quot; rel=&quot;nofollow noreferrer&quot;&gt;Corse island&lt;/a&gt; (the birth place of &lt;a href=&quot;https://en.wikipedia.org/wiki/Napoleon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Napoleon Bonaparte&lt;/a&gt;). Their business has known ups and downs several times, they are now part of Dubreuil Group. Corsair 747 had over time famous &lt;a href=&quot;https://www.aeroport-paris-orly.com/corsair-et-les-747&quot; rel=&quot;nofollow noreferrer&quot;&gt;tail numbers&lt;/a&gt;: &lt;a href=&quot;https://www.jetphotos.com/photo/362669&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-GSEA&lt;/a&gt;, &lt;a href=&quot;https://www.jetphotos.com/photo/5758953&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-GSEX&lt;/a&gt;, &lt;a href=&quot;https://www.jetphotos.com/photo/366891&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-GSUN&lt;/a&gt;, F-GSKY, F-HLOV, etc.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/47ZQF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/47ZQF.jpg&quot; alt=&quot;F-GSEA landing at St Marteen&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;F-GSEA landing at Princess Juliana. Source: &lt;a href=&quot;https://www.jetphotos.com/photo/336672&quot; rel=&quot;nofollow noreferrer&quot;&gt;JetPhotos&lt;/a&gt;, photo by &lt;a href=&quot;https://www.jetphotos.com/photographer/7353/photos&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rogier van der Velde&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-11-11T12:42:17.503" LastActivityDate="2020-11-11T12:42:17.503" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="22348" PostTypeId="1" CreationDate="2015-10-25T00:33:11.000" Score="3" ViewCount="294" Body="&lt;p&gt;I am currently 17 years old and next year I will be graduating from  high school. My plan is to go to the Air force and become a Tactical Aircraft Mechanic. Obviously I am going to go through BMT and then Tech school. But after I learn that career I want to work at an Airline. How does that work specifically? &lt;/p&gt;&#xA;" OwnerUserId="11982" LastEditorUserId="19" LastEditDate="2017-01-10T10:48:46.673" LastActivityDate="2019-06-21T13:10:23.310" Title="How can I progress from tactical aircraft mechanic in the air force to an airline?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22349" PostTypeId="1" AcceptedAnswerId="22358" CreationDate="2015-10-25T01:03:56.047" Score="10" ViewCount="1145" Body="&lt;p&gt;Under FAA rules a license for gliders doesn't require a medical certification and you can get your license at 16 rather than 17 for powered aircraft. You can get your student license two years sooner at age 14. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears to me that gliding would require MORE skill and experience than a powered aircraft. It looks very unforgiving. You only have one shot at landing, there is no go-around. If you lose too much altitude you could end up not being able to reach the airport. You have to know how to find thermals, etc to gain altitude. While being towed you will be flying in closer proximity to another aircraft than you normally would in a powered airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are the restrictions less for a glider?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="572" LastEditDate="2015-10-25T18:54:44.567" LastActivityDate="2020-12-07T21:26:41.127" Title="Why do glider licences have fewer restrictions than powered aircraft?" Tags="&lt;faa-regulations&gt;&lt;glider&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22350" PostTypeId="1" AcceptedAnswerId="22509" CreationDate="2015-10-25T01:21:32.790" Score="1" ViewCount="5115" Body="&lt;p&gt;See these questions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/21790/9491&quot;&gt;What is balanced field length?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/21783/9491&quot;&gt;What are runway declared distances?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My multi-engine jet airplane uses a balanced field length concept.  Most airports served by airliners have declared distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, my takeoff distance can't be longer than the runway length.  Does it have to be lower than all the declared distances?  TODA?  TORA?  ASDA?  LDA?&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-09-11T06:10:29.350" Title="How do runway declared distances affect my takeoff distance?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;performance-calculation&gt;&lt;declared-distances&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22351" PostTypeId="1" AcceptedAnswerId="22820" CreationDate="2015-10-25T01:29:51.883" Score="8" ViewCount="2331" Body="&lt;p&gt;Can I accept a clearance containing a &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_Instrument_Departure&quot; rel=&quot;noreferrer&quot;&gt;Standard Instrument Departure&lt;/a&gt; (SID) with a climb gradient that I can easily make on all my engines but can't make the required gradient on one engine inoperative?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I can and I lose an engine on departure what should I do so I don't hit anything? &lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="5517" LastEditDate="2015-10-26T17:23:02.870" LastActivityDate="2015-11-10T09:19:12.573" Title="Can I accept a SID if I can't make the required climb gradient on a single engine but have no problem on two engines?" Tags="&lt;faa-regulations&gt;&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;far-91&gt;&lt;departure-sid&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22353" PostTypeId="2" ParentId="22338" CreationDate="2015-10-25T03:12:08.137" Score="13" Body="&lt;p&gt;In general, no- except in emergencies or 'small' hurricanes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Commercial aircraft usually fly &lt;em&gt;around&lt;/em&gt; bad weather (like hurricanes), not over it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some of the hurricanes can reach upto 50,000+ ft height, making it all but impossible for most modern commercial aircraft to fly over them (except maybe you're flying a Concorde). Even for smaller storms, the convective process over the hurricane will cause severe turbulence, affecting overflying flights.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even for hurricanes where the  aircraft can fly over, there is the problem of safety- What will happen is something happens (for example engine failure) and the aircraft has to descend to lower altitudes? Obviously no one wants to descend into the storm.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are some aircraft &lt;a href=&quot;http://www.hurricanehunters.com/&quot; rel=&quot;noreferrer&quot;&gt;that do fly into hurricanes&lt;/a&gt; for scientific experiments. These are crewed by trained (and experienced) specialists and &lt;a href=&quot;http://www.huffingtonpost.com/2012/10/29/flying-into-hurricane-ire_n_936225.html?ir=India&amp;amp;adsSiteOverride=in&quot; rel=&quot;noreferrer&quot;&gt;involve a lot of detailed planning&lt;/a&gt;. For example, the aircraft are equipped with radar that helps in avoiding the worst parts of the storm. Still, it is risky and the aircraft is exposed to significant loads and vibrations not usually exposed in commercial service.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-25T03:12:08.137" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22357" PostTypeId="2" ParentId="22346" CreationDate="2015-10-25T05:54:19.903" Score="13" Body="&lt;p&gt;The wing folding mechanisms (in aircraft) and rotor folding mechanisms (in helicopters) are different. The V-22 Osprey falls somewhere in the middle.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of aircraft, the wing folding mechanism is usually made of high grade steel (or titanium in some cases) and actuated either hydraulically (or in recent cases) electrically. The outer wing rotates about a hinge, to which the two parts (inboard and outboard) of the wings are locked. For example, the F/A 18 wing folding mechanism looks something like this:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6hwCy.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6hwCy.png&quot; alt=&quot;Wing folding mechanism&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from US Patent &lt;em&gt;Wing fold push-pin locking assembly US 5558299 A&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, once the wings are either folded (or unfolded), they are locked using very hefty sliding pins which provide a secure mechanical connection once (they) slid into place in sockets in the outer wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, incidents do happen, usually because the pins have not locked and not because of failure. A number of incidents have happened where aircraft have taken off with wings folded (and landed safely, surprisingly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JcP2b.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JcP2b.jpg&quot; alt=&quot;Flight with folded wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source : reddit.com/theaviationist.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of helicopters, the blade folding method is more or less the same with some variations- pull the pin that holds the blade (on one side) and fold the blades, which is done manually for small helicopters and hydraulically for large ones. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qLV6x.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qLV6x.jpg&quot; alt=&quot;Folded wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: reddit.com &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are then held either by hydraulic pressure or mechanical attachments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LQwq2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LQwq2.jpg&quot; alt=&quot;Blades in folded position&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: adf-messageboard.com.au&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At-least in helicopters, there is little chance of a takeoff with the wings folded.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The V-22 Osprey is a special case- The propellers (or rotors) is folded first, then the engines are rotated, followed by the wings themselves.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-25T05:59:28.540" LastActivityDate="2015-10-25T05:59:28.540" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22358" PostTypeId="2" ParentId="22349" CreationDate="2015-10-25T07:00:43.853" Score="12" Body="&lt;p&gt;First of all, gliders fly slowly. Everything happens more slowly than in other aircraft, and this helps to make flying them less challenging than you might think. Flying them well is a different matter - this requires a lot of skill and good physical health.&lt;/p&gt;&#xA;&lt;p&gt;Historically, the early age limits were introduced in Nazi Germany when the Deutscher Luftstportverband (&lt;a href=&quot;https://en.wikipedia.org/wiki/German_Air_Sports_Association&quot; rel=&quot;nofollow noreferrer&quot;&gt;DLSV&lt;/a&gt;) and later the &lt;a href=&quot;https://en.wikipedia.org/wiki/National_Socialist_Flyers_Corps&quot; rel=&quot;nofollow noreferrer&quot;&gt;NSFK&lt;/a&gt; organized groups of adolescents to let them build and fly gliders. Flight training started at the age of 14, mostly in very simple, &lt;a href=&quot;https://en.wikipedia.org/wiki/Gliding#Bungee_launch&quot; rel=&quot;nofollow noreferrer&quot;&gt;bungee-launch&lt;/a&gt;ed gliders like the Zögling or &lt;a href=&quot;https://en.wikipedia.org/wiki/DFS_SG_38_Schulgleiter&quot; rel=&quot;nofollow noreferrer&quot;&gt;SG-38&lt;/a&gt; which were flown in summer and built or repaired in Winter. Since bungee launching is a very labor-intensive process and flights last only a few seconds, this was less about pilot training than keeping the young occupied and under the influence of the Nazi party.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4kpfa.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4kpfa.png&quot; alt=&quot;Bungee launch of a Zögling&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Bungee launch of a Zögling glider (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f3/Bundesarchiv_Bild_102-11640%2C_Gatower_Berge%2C_Studenten_beim_Segelfliegen.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;And it worked. Accidents did happen, but were almost never fatal since all operations happened at low speed and altitude. Therefore, these age limits were exported together with the idea of flying unpowered aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Note that in Europe the same health certificate is required for glider flying as for flying GA aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Now to your concerns about the demanding nature of gliding:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Glider flying is done from airfields which are suitable for GA aircraft (or the gliders could not be aerotowed) or winch launching. 800 meters is about the minimum, and this leaves plenty of space to land a glider.&lt;/li&gt;&#xA;&lt;li&gt;Flight training is done initially only in the direct vicinity of the airfield, and students are supposed to stay within a cone which allows them to reach the airfield at any moment. Flying cross-country comes much later, when the students have made more than a hundred landings and know how to get the plane down in a certain spot. Again, the slow speed helps to make such landings simple if the pilot is prepared.&lt;/li&gt;&#xA;&lt;li&gt;Today, training is initially in two-seaters, so there is an experienced pilot around for the first landings and the first cross-country flights.&lt;/li&gt;&#xA;&lt;li&gt;Aerotowing is also quite simple, and altitude management while in tow is more challenging than keeping the right distance from the towplane. Again, this is done initially in two-seaters, and all the glider pilot has to do is to fly with the same bank angle as and slightly above the towplane. The rope takes care of the rest.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="31425" LastEditDate="2020-12-07T21:26:41.127" LastActivityDate="2020-12-07T21:26:41.127" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="22359" PostTypeId="1" AcceptedAnswerId="22360" CreationDate="2015-10-25T08:31:24.667" Score="2" ViewCount="688" Body="&lt;p&gt;While calculating the off design conditions of the engine, we need to know the off design characteristics, such as &lt;strong&gt;inlet additive drag&lt;/strong&gt;. In the book &lt;em&gt;Mechanics of Flight&lt;/em&gt;, by Warren F. Phillips, its expression has been derived as a relation between free stream and inlet Mach no. Further while calculating the drag,in one of the example &lt;strong&gt;&lt;em&gt;(2.6.1)&lt;/em&gt;&lt;/strong&gt;, the inlet Mach no. has been assumed constant at 0.6 whereas the flight is accelerating from Mach 0 to its design Mach no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This implies that the inlet Mach no. has been somehow achieved as 0.6 even at takeoff, is it practically possible? If not, then how is the drag actually calculated during flight with varying free stream and inlet Mach numbers?&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="5517" LastEditDate="2015-10-26T16:32:03.990" LastActivityDate="2015-10-26T16:32:03.990" Title="Is it possible to control the inlet Mach no. of the engine during flight?" Tags="&lt;jet-engine&gt;&lt;drag&gt;&lt;inlet&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-26T20:17:17.867" ContentLicense="CC BY-SA 3.0" />
  <row Id="22360" PostTypeId="2" ParentId="22359" CreationDate="2015-10-25T09:00:09.800" Score="2" Body="&lt;p&gt;The inlets of supersonic aircraft routinely control (reduce) the Mach number of the engine (at compressor inlet) during flight. This is done using either a 2D ramp type inlet (like Concorde) or a center body (like Mig-21).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These inlets convert the incoming supersonic flow to subsonic flow by forming shock waves in the path of the airflow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CX0YG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CX0YG.jpg&quot; alt=&quot;Adjustable inlet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: sturgeonshouse.ipbhost.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In subsonic conditions, the inlets perform two functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;At cruise condition, diffusion of the free-stream flow to the compressor inlet condition.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At takeoff, acceleration of static air to the compressor inlet condition.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So basically, the inlet design can be optimized such that the Mach number is constant (within some variation) over the engine operational range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your case, however, I think that it is a simplifying assumption made for the problem.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="595" LastEditDate="2015-10-25T17:47:48.460" LastActivityDate="2015-10-25T17:47:48.460" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22361" PostTypeId="2" ParentId="22350" CreationDate="2015-10-25T09:14:35.940" Score="1" Body="&lt;p&gt;Actually, the take off distance given in runways will be greater than the runway distance as it will include the distance to overcome a predetermined obstacle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tyB2G.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tyB2G.gif&quot; alt=&quot;Take off distance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: tc.gc.ca&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The balanced field length is dependent on the aircraft configuration among other things and is usually available in AFM. The airfield lengths, on the other hand are made available so that operators can decide which aircraft to operate based on the runway lengths available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the ASDA should give you the available distance for taking off as it gives the required field length available in case you decide to abort the takeoff for whatever the reasons. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-25T09:14:35.940" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22362" PostTypeId="1" AcceptedAnswerId="22366" CreationDate="2015-10-25T11:23:04.980" Score="2" ViewCount="1389" Body="&lt;p&gt;The different types of check (A-check to D-check) require different types of competence and certification. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I understand correctly, D-checks require special equipment and certification and some airlines developed whole subsidiaries to take care of this task (&lt;a href=&quot;https://en.wikipedia.org/wiki/Lufthansa_Technik&quot; rel=&quot;nofollow&quot;&gt;LHT&lt;/a&gt;, &lt;a href=&quot;http://www.airfranceindustries.com/AFIKLMEM/en/g_page_standard/AboutAFIKLMEM/Overview.html&quot; rel=&quot;nofollow&quot;&gt;AFI&lt;/a&gt;,...) in which they send their aircraft to perform a D-check. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the existence of those subsidiaries, I assume that a D-check cannot be performed by the airline's employee and must be performed by a company specialized in aircraft maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A-checks and daily maintenance do not require the same amount of qualifications, certification and equipment and may thus be performed by the airline without sending the aircraft to a specialized place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For each check (A-check, B-check, C-check and D-check), who is qualified to perform those checks? Can these checks be performed by the airline itself or must a specialized company take responsibility for the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="595" LastEditDate="2015-10-25T12:05:16.050" LastActivityDate="2015-10-26T22:49:13.877" Title="Who can perform different maintenance checks?" Tags="&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22363" PostTypeId="2" ParentId="22074" CreationDate="2015-10-25T11:50:07.420" Score="13" Body="&lt;p&gt;There is hardly anything that can't be found with the help of a few friends and the Library of Congress. &lt;a href=&quot;https://books.google.com/books/about/%D0%98%D1%81%D1%82%D1%80%D0%B5%D0%B1%D0%B8%D1%82%D0%B5%D0%BB%D1%8C_%D0%9C%D0%98%D0%93_15.html?id=r8HUAAAACAAJ&quot; rel=&quot;noreferrer&quot;&gt;&quot;Истребитель МИГ-15 (MiG-15 Fighter)&quot; ISBN 9785857290194&lt;/a&gt; Pp.52-57.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plant No.1 (Kuibyshev):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15    MiG-15bis    MiG-15Pbis     UTI MiG-15bis&#xA;1949 Plan    550       &#xA;     Actual  510&#xA;1950 Plan    300       350                          50&#xA;     Actual  301       401                          50&#xA;1951 Plan              792         5               365 &#xA;     Actual            820         5               371&#xA;1952 Plan              425                         315&#xA;     Actual            460                         333&#xA;1953 Plan              &#xA;     Actual    2                                   127&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Non-flyable [what the heck is that??] MiG-15: 2 in 1949, 4 in 1950.&#xA;10 knock-down UTI MiG-15 kits were produced in 1951.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plant No. 153 - Novosibirsk&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15    MiG-15bis    MiG-15Pbis     UTI MiG-15bis&#xA;1949 Plan    550       &#xA;     Actual  144&#xA;1950 Plan    300        500                         &#xA;     Actual  308        360                         &#xA;1951 Plan              1173                         &#xA;     Actual    1       1196                        &#xA;1952 Plan               840                         &#xA;     Actual             863                         &#xA;1953 Plan                                          200&#xA;     Actual               1                        209&#xA;1954 Plan                                          700&#xA;     Actual                                        715&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.381 (Leningrad): 1949 - 75 MiG-15&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plant No.21 (Gor'ky):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15bis (type 53)    MiG-15Rbis (type 55)&#xA;1950 Plan    350                                             &#xA;     Actual  367                                &#xA;1951 Plan    937                     60                         &#xA;     Actual  992                     64                        &#xA;1952 Plan    395                    300                         &#xA;     Actual  425                    300                         &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.31 - Tbilisi&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15bis (art. 50)&#xA;1951 Plan     30                         &#xA;     Actual   35                        &#xA;1952 Plan    190                         &#xA;     Actual  190                         &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.126 - Komsomo'ls'k-NA-Amure&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15                 MiG-15bis&#xA;1950 Plan                           250                         &#xA;     Actual    1                     42            &#xA;1951 Plan                           337                         &#xA;     Actual                         362                    &#xA;1952 Plan                           400                         &#xA;     Actual                         428                         &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.292 - Saratov&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;             MiG-15    MiG-15bis    MiG-15Sbis&#xA;1950 Plan              275                                   &#xA;     Actual    8?      131                         &#xA;1951 Plan              457          100                           &#xA;     Actual            509           49                        &#xA;1952 Plan              350                                  &#xA;     Actual            354                                   &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.135 - Kharkiv&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                UTI MiG-15&#xA;1950 Plan              25                                   &#xA;     Actual             6                         &#xA;1951 Plan              50                                    &#xA;     Actual            50                                 &#xA;1952 Plan             150                                  &#xA;     Actual            85&#xA;1953 Plan             150&#xA;     Actual           158&#xA;1954 Plan             200&#xA;     Actual           212&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Plant No.99 (Ulan-Ude)                                   &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                UTI MiG-15&#xA;1951 Plan              75                                    &#xA;     Actual            29                                 &#xA;1952 Plan             125                                  &#xA;     Actual            53&#xA;1953 Plan             150&#xA;     Actual           127&#xA;1954 Plan             200&#xA;     Actual           206&#xA;1955 Plan             225&#xA;     Actual           245&#xA;1956 Plan              &#xA;     Actual           173&#xA;1957 Plan              &#xA;     Actual           113&#xA;1958 Plan              &#xA;     Actual           106&#xA;1959 Plan              &#xA;     Actual            65&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Totals for the USSR (may contain errors, haven't double-checked):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;|      | Combat MiG-15 and variants |  UTI MiG-15   |&#xA;| Year | Plan          | Actual     | Plan | Actual |&#xA;| 1949 | 1175          |  729       |    0 |    0   |&#xA;| 1950 | 2325          | 1911       |   75 |   56   |&#xA;| 1951 | 3891          | 4033       |  490 |  450   |&#xA;| 1952 | 2900          | 3020       |  590 |  471   |&#xA;| 1953 |    0          |    3       |  500 |  621   |&#xA;| 1954 |               |            | 1100 | 1133   |&#xA;| 1955 |               |            |  225 |  245   |&#xA;| 1956 |               |            |    0 |  173   |   &#xA;| 1957 |               |            |    0 |  113   |&#xA;| 1958 |               |            |    0 |  106   |&#xA;| 1959 |               |            |    0 |   65   |&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="337" LastEditorUserId="1444" LastEditDate="2015-10-26T18:49:52.613" LastActivityDate="2015-10-26T18:49:52.613" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22364" PostTypeId="1" CreationDate="2015-10-25T12:11:46.477" Score="4" ViewCount="462" Body="&lt;p&gt;I want to see if a propeller is bad or good for generating static thrust. This is what I know about the propeller and the engine used to turn it during a test:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine shaft power, $P$ = 0.58 hp&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller diameter, $D$ = 8.5 ft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Revolutions per minute, $RPM$ = 245 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static thrust, $T$ = 18.75 lbf&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I calculate the efficiency of the propeller? What is the maximum achievable efficiency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Additional explanations&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The formula I was suggested to use could be exactly what I need. However, using it, I do not get some reported experimental results like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine shaft power, $P$ = 6 hp&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller diameter, $D$ = 8.5 ft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static thrust, $T$ = 66 lbf&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller efficiency, $\eta_{prop} \geq 66\%$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gear efficiency, $\eta_{gears} \geq 85\%$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing the calculations: $\eta_{prop} = \sqrt{\frac{T^3}{(P^2 \cdot \pi \cdot \eta_{gears} \cdot \frac{D^2}{2} \cdot \rho )}} = 37.2\%$ which is well below 66%.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-28T03:47:09.900" LastActivityDate="2015-10-28T03:47:09.900" Title="Is this a good or a bad propeller?" Tags="&lt;propeller&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22365" PostTypeId="2" ParentId="22364" CreationDate="2015-10-25T14:17:13.623" Score="1" Body="&lt;p&gt;&lt;em&gt;Engine shaft power: P = 0.58 hp, Propeller diameter: D = 8.5 ft, RPM = 245, Static thrust: T = 18.75 lbf&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\eta_{prop} = \sqrt{\frac{T^3}{(P^2 \cdot \pi \cdot \frac{D^2}{2} \cdot \rho )}} = 49.5\%$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\rho=1.2 \frac{kg}{m^3}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So at an efficiency of 49.5% that propeller is rather poor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I used the formula that relates static thrust to efficiency, power and propeller diameter from &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-28T03:43:38.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22366" PostTypeId="2" ParentId="22362" CreationDate="2015-10-25T15:34:08.550" Score="2" Body="&lt;p&gt;Airlines are free to conduct the tests wherever they prefer as long as they meet the required FAA standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An extract from American Airlines' Procedures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&quot;PS&quot; Daily Checks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each aircraft is checked every 2-3 days in its &quot;PS&quot; (Periodic Service) check. The aircraft is visually inspected and its maintenance log book is checked for entries and maintenance needs. The &quot;PS&quot; check can be performed overnight or during downtime during the flight day. It averages approximately two manhours.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&quot;A&quot; Checks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;A&quot; check is more detailed than the &quot;PS&quot; check. &quot;A&quot; checks are performed every 7- 9 days (approximately 80 - 100 flight hours). The &quot;A&quot; check is performed at one of 40 stations around American’s system. It averages 10 - 20 man-hours.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&quot;B&quot; Checks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;B&quot; check is an even more thorough maintenance check. The &quot;B&quot; check is accomplished approximately every two months (roughly 500 - 600 flight hours). Besides specific service performed on the aircraft, a detailed series of systems and operational checks are performed. American always performs &quot;B&quot; checks inside one of its hangars at seven different cities around its system. A &quot;B&quot; check requires approximately 100 man-hours on narrowbody aircraft (those with only one aisle) and approximately 200 - 300 man-hours on widebody aircraft (those with two aisles).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&quot;C&quot; Checks&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;C&quot; check is the most thorough type of maintenance work performed by American. The airframe - virtually the entire aircraft - goes through an exhaustive series of checks, inspections and overhaul work. It is performed at either of American’s heavy maintenance and engineering centers in Tulsa, Oklahoma or the Alliance Maintenance Facility in Fort Worth, Texas. There are different levels of &quot;C&quot; checks depending on the type of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Jet Engine Overhauls&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern jet engines are among the most reliable devices in aviation. American does not replace and overhaul jet engines at a specific number of hours. Instead, American uses a 24- hour-a-day &quot;condition monitoring&quot; process that scientifically tracks the condition of every engine on every aircraft. Besides visual inspection, technicians monitor the internal condition of every engine, using such procedures as boroscope inspections and oil sample spectographs. The goal is to replace and overhaul an engine before a problem can occur. Engine overhauls are performed at the Tulsa and Alliance-Fort Worth Maintenance and Engineering facilities. The engine replacement is usually performed at one of the six &quot;B&quot; check hangar locations around the country.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To answer your question on the qualifications required to perform these checks, we'd have to go to FARs Part 65 which lists the privileges and limitations of a Mechanic Certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the basic Mechanic Certificate, FAA allows two different ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first one is the &lt;strong&gt;Airframe Rating&lt;/strong&gt; which, under &lt;strong&gt;§65.85&lt;/strong&gt;, states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A mechanic who holds an airframe rating may approve and return to&#xA;  service an airframe, an appliance, or any related part after he or she&#xA;  has performed, supervised, or inspected minor repairs or alterations.&#xA;  He or she may also perform the maintenance actions required for a&#xA;  major repair or alteration, and should initiate the appropriate form&#xA;  (FAA Form 337, Major Repair and Alteration) associated with that work.&#xA;  However, the return to service action must be accomplished by a&#xA;  certificated A &amp;amp; P technician holding an Inspection Authorization&#xA;  (IA). (Refer to 14 CFR §65.95.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After that comes the &lt;strong&gt;Powerplant Rating&lt;/strong&gt; under &lt;strong&gt;§65.87&lt;/strong&gt; which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Similarly, a mechanic holding a powerplant rating has the same&#xA;  limitations imposed regarding the powerplant and propeller as the&#xA;  airframe technician has on the airframe rating. He or she may perform&#xA;  and return to service minor repairs or alterations. He or she may also&#xA;  accomplish the work activities required for a major repair or&#xA;  alteration, but the work must be signed off for return to service by&#xA;  an IA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That said, after all the checks have been performed, a person with &lt;strong&gt;Inspection Authorization&lt;/strong&gt; (under &lt;strong&gt;§65.91&lt;/strong&gt;) is responsible to approve the aircraft for return to service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://www.aa.com/content/images/aboutUs/newsroom/fs_aircraft_maintenance_procedures.pdf&quot; rel=&quot;nofollow&quot;&gt;American Airlines Aircraft Maintenance Procedures Fact Sheet&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="11136" LastEditDate="2015-10-26T22:49:13.877" LastActivityDate="2015-10-26T22:49:13.877" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22367" PostTypeId="1" CreationDate="2015-10-25T16:01:56.550" Score="13" ViewCount="1520" Body="&lt;p&gt;Here's the scenario: There is a Private Pilot working on their instrument rating. Alongside with him is their CFII. Let's say it is just a normal VFR flight, and they're getting back to their home airport after a training flight. Now, after the first radio call, ATC instructs them &quot;NXYZ, Squawk 1234 and ident - remain outside (Airport) Class Charlie&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though you just need Two-Way Radio Communications to enter Class C, ATC has strictly advised them to remain outside of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, for some reason, the airplane goes well inside Class C airspace. After a few minutes, ATC gives a call saying &quot;NXYZ, cleared into Class C, enter left base Runway 18. Possible pilot deviation, advise when ready to copy down a phone number&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is - since both the Private Pilot and the Instructor are logging the flight time as PIC, who is responsible to answer? And if a deviation is given - who among the two gets it?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="1696" LastEditDate="2016-06-14T16:54:00.820" LastActivityDate="2016-06-15T01:52:59.213" Title="Who is responsible - CFII or the Private Pilot?" Tags="&lt;faa-regulations&gt;&lt;cfi&gt;&lt;pic&gt;&lt;pilot-authority&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22369" PostTypeId="2" ParentId="22367" CreationDate="2015-10-25T18:09:51.613" Score="8" Body="&lt;p&gt;There is a contradiction in your question.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say both the student and instructor are logging PIC.  This is fine, but the authority for this to happen depends on certain things.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The instrument student logs PIC under 61.51(e)(1)(i)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They are acting as PIC as the sole manipulator of the controls and must be rated for the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The instructor logs PIC under 61.51(e)(3)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) A certificated flight instructor may log pilot in command flight time for all flight time while serving as the authorized instructor in an operation if the instructor is rated to act as pilot in command of that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This only applies on instructional flights, where the instructor is providing instruction and is rated to act as PIC (e.g. if the instructor lacks a medical and could not act as PIC, they could still provide instruction if the student is the PIC, but the instructor would not be able to log PIC).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The reason I say this is a contradiction is that you claim &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's say it is just a normal VFR flight, and they're getting back to their home airport after a training flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This makes it sound like it is not a training flight and in that case only one of the pilots could log PIC using the sole manipulator rule in the absence of instruction taking place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It turns out the above isn't directly important, as logging != acting PIC, and the acting legal PIC is what matters from an authority and enforcement perspective.  What the above logging issue gets at is hinting at who might be the legal PIC absent the two pilots agreeing who would act as the legal PIC.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case instruction is taking place even though the student is logging PIC  the instructor is also logging PIC and is the &quot;ranking&quot; pilot in the flight and may be viewed as the legal PIC.  In the case of a non-training flight (which would be hard to justify if you both logged PIC), then it comes down to the question -- who agreed to act as the legal PIC?  Either of the student or instructor could act as the legal PIC, but on a non-training flight only the one of you actually manipulating the controls could log PIC.  If there was no agreement prior to the flight over who is the legal PIC, the FAA will still probably decide the CFII was the legal PIC or the FAA may decide to go after both of you.  I believe there is precedent for this in enforcement action, but I don't have any cases handy to reference.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What should you do about this?  &lt;strong&gt;Both the student and the instructor should &lt;a href=&quot;http://asrs.arc.nasa.gov/report/electronic.html&quot;&gt;fill out a NASA ASRS form&lt;/a&gt; and preserve evidence that you submitted it within 10 days of the event.&lt;/strong&gt;  If the deviation was not willful and the controller decides to pursue action, this will protect you from enforcement. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-10-25T18:47:14.047" LastActivityDate="2015-10-25T18:47:14.047" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22371" PostTypeId="1" CreationDate="2015-10-25T19:15:33.050" Score="7" ViewCount="1323" Body="&lt;p&gt;Some airlines have duty-free carts (2) with items for sale on board. It seems that only a few items get sold each flight. Does the profit from selling a few items justify the cost of having this extra weight/volume on board?&lt;/p&gt;&#xA;" OwnerUserId="2560" LastEditorUserId="64" LastEditDate="2015-10-30T02:53:53.547" LastActivityDate="2016-01-04T12:12:22.593" Title="Does the profit from selling duty-free items on board justify flying the carts?" Tags="&lt;airline-operations&gt;" AnswerCount="2" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="22372" PostTypeId="2" ParentId="22367" CreationDate="2015-10-25T20:50:06.963" Score="3" Body="&lt;p&gt;This really depends on whether or not the authorized instructor and / or the pilot can legally be the pilot in command.  By this I mean they are current with a flight review.  Neither the student pilot nor the flight instructor need to be landing current as the purpose of the flight is a training flight.  See the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2006/kortokrax%20-%20(2006)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow&quot;&gt;Kortokrax interpretation&lt;/a&gt; from the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both the student pilot and the instructor is capable of acting as the pilot in command it should be discussed before hand who will be acting as the pilot in command before the flight.  I know of some instructors who keep a binder in their car stating who is the acting pilot in command if an incident or accident occurs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In you situation, without the pilots discussing beforehand, I would imagine the FAA would hold the instructor accountable.  They have more experience and should of prevented the incursion.  I have heard the FAA holding the instructor or another more experienced pilot accountable even though it was expressly documented the other pilot was acting as the legal pilot in command.  In their view, the more experienced pilot should have said / done something to prevent what happened.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2016-06-15T01:52:59.213" LastActivityDate="2016-06-15T01:52:59.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22376" PostTypeId="2" ParentId="12823" CreationDate="2015-10-26T04:40:47.923" Score="3" Body="&lt;p&gt;This is more in the way of a comment regarding the F-4 incident. In 1969 an F-4J launched off the #1 cat off USS Ranger. The plane failed to gain suffiecient airspeed and went in the water. The RIO safely ejected. The pilot was lost. All that was recovered was his shattered helmet. The only possibility is that his canopy did not clear the plane before his ejection. I can provide the log of the incident if so desired. I was serving on the Ranger at the time. I am now the webmaster for Ranger's History &amp;amp; Memorial site. I have the logs for that cruise.&lt;/p&gt;&#xA;" OwnerUserId="11991" LastActivityDate="2015-10-26T04:40:47.923" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22377" PostTypeId="1" AcceptedAnswerId="22379" CreationDate="2015-10-26T09:12:43.713" Score="34" ViewCount="9331" Body="&lt;p&gt;On aircraft with 2 crew placed one in front of each other (tandem) equipped with ejection seats, the rear seat is ejected before the front one (described &lt;a href=&quot;https://aviation.stackexchange.com/a/12826/3394&quot;&gt;here for the F-14&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why is the rear seat ejected before the front one? &lt;/li&gt;&#xA;&lt;li&gt;Is an aircraft without ejection seat (e.g. glider) evacuated in the same order and why?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-27T20:17:48.283" Title="Why is the rear seat ejected before the front one?" Tags="&lt;evacuation&gt;&lt;ejection-seat&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22379" PostTypeId="2" ParentId="22377" CreationDate="2015-10-26T09:51:31.860" Score="54" Body="&lt;p&gt;If the front seat ejected first, the drag would probably bring him too close in the trajectory of the rear seat, thus making a collision of both probable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the rear seat is ejected first, it experiences drag earlier than the front seat and will thus not have an increased probability of hitting it.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-10-26T09:51:31.860" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22380" PostTypeId="2" ParentId="22377" CreationDate="2015-10-26T10:17:36.037" Score="43" Body="&lt;p&gt;In general, in aircraft with tandem seating, the rear seat (having the Radar Officer) ejects first, followed by the forward (pilot) seat, after a delay of ~0.3 seconds. This is done for a few reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the pilot seat is ejected first (or both are ejected simultaneously), there is a possibility that the pilot seat may collide (as it will be dragged backwards due to wind force) with the copilot seat or damage the (rear) canopy during ejection.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In some aircraft, the pilot can eject only after the rear seat is ejected. This is so that, in case the rear seat fails to eject, the pilot can still control the aircraft and 'pop out' the Radar officer's seat by maneuvering. For example, the F-4 procedure called for the pilot to roll the aircraft inverted with a positive 'g' and then pop the radar officer with a negative 'g'.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In some cases like the (Mig-15 UTI), the rear seats were ejected first simply because the gas jets from the pilot seat ejection mechanism made ejecting from the rear compartment impossible. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-26T10:23:17.293" LastActivityDate="2015-10-26T10:23:17.293" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22381" PostTypeId="1" CreationDate="2015-10-26T10:32:19.920" Score="18" ViewCount="7695" Body="&lt;p&gt;Why are aircraft tyres not grooved horizontally like vehicle tyres? If the tyres are grooved horizontally won't it help in achieving more friction and reduce the chances of veering off?&lt;/p&gt;&#xA;" OwnerUserId="8866" LastEditorUserId="9276" LastEditDate="2015-10-26T14:23:46.137" LastActivityDate="2017-12-05T09:22:32.247" Title="Why are aircraft tyres not grooved horizontally?" Tags="&lt;aircraft-performance&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22382" PostTypeId="2" ParentId="22381" CreationDate="2015-10-26T11:30:16.923" Score="13" Body="&lt;p&gt;It's certainly not universally true that all aircraft have length wise grooved tyres only.&lt;br/&gt;&#xA;Especially aircraft designed for use from rough and unprepared strips often have heavy duty tyres to deal with such conditions.&lt;br/&gt;&#xA;Think some military aircraft especially.&#xA;Here's an example of a Sea Fury deployed in Korea during the war there for example:&lt;br/&gt;&#xA;Linked from &lt;a href=&quot;http://www.3rdattackgroup.com/13th-korea-personnel---aircraft.php&quot; rel=&quot;noreferrer&quot;&gt;www.3rdattackgroup.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Rq9uB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rq9uB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is the He-111:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vLzCJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vLzCJ.jpg&quot; alt=&quot;Wheel detail of a He-111&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture &lt;a href=&quot;http://www.wwiiaircraftphotos.com/LCBW11/He111-74f-s.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;. The link points to the full picture.&lt;/p&gt;&#xA;" OwnerUserId="900" LastEditorUserId="1961" LastEditDate="2015-10-26T13:17:46.227" LastActivityDate="2015-10-26T13:17:46.227" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22383" PostTypeId="2" ParentId="22381" CreationDate="2015-10-26T12:15:55.143" Score="17" Body="&lt;p&gt;Almost all the aircraft operating from prepared surfaces have circumferential grooves in order to remove water between the tyre and runway surface.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.dunlopaircrafttyres.com/tech_support/aircraft-tyre-technology.aspx&quot; rel=&quot;noreferrer&quot;&gt;Dunlop site&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Most Dunlop aircraft tyre designs feature circumferential grooves moulded into the tread to disperse water from beneath the tread in wet runway conditions.&lt;/p&gt;&#xA;&lt;p&gt;The tread helps to reduce the risk of aqua planing and improves traction and grip between the tread and runway surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In 1960s, NASA carried out a number of studies to determine the effect of tread design (among other things) for operating on wet runways and settled on the circumferential groove shape.&lt;/p&gt;&#xA;&lt;p&gt;In case of aircraft operated from unpaved surfaces, the tyres may have some type of cross-tread pattern.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-26T12:15:55.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22384" PostTypeId="1" CreationDate="2015-10-26T14:10:56.763" Score="3" ViewCount="683" Body="&lt;p&gt;I was looking at return flights from London - Azores islands and was astonished to see the huge difference in flight times, both flights are via Ryanair:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;out: 3 hr 5 min&#xA;return: 4 hr 45 min&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cI1YJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cI1YJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am aware of differences due to wind conditions/jet streams and routes etc but for the return flight to take &gt;50% longer really surprised me. What is likely to be the cause of this? &lt;/p&gt;&#xA;" OwnerUserId="9014" LastActivityDate="2015-10-26T22:52:01.420" Title="Why this huge discrepancy in flight times?" Tags="&lt;flight-schedules&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22385" PostTypeId="1" AcceptedAnswerId="22387" CreationDate="2015-10-26T14:17:22.507" Score="16" ViewCount="21374" Body="&lt;p&gt;I know that the most civilian engines use a high bypass ratio which is good for fuel economy and noise reduction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What prevents military engines from using the same technology instead of opting for low bypass engines?&lt;/p&gt;&#xA;" OwnerUserId="11615" LastEditorUserId="1696" LastEditDate="2015-10-26T21:04:22.523" LastActivityDate="2019-03-23T18:49:36.413" Title="Why do military turbofan engines use a low bypass ratio?" Tags="&lt;turbofan&gt;&lt;bypass-ratio&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22386" PostTypeId="2" ParentId="22384" CreationDate="2015-10-26T14:43:38.773" Score="1" Body="&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; Probably &quot;Operational&quot; reasons&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I would hazard a guess that this is a combination of a few factors&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A longer route flown inbound to London&lt;/li&gt;&#xA;&lt;li&gt;Flying in to a busy airspace like London requiring particular routing, particularly oft requiring length hold patterns&lt;/li&gt;&#xA;&lt;li&gt;The time of day the flight in to London arrives being particularly busy (late afternoon/early evening)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;These three factors may cause the airline to list the flight duration as longer than it would usually, in order to account for the possibility of a lengthy flight time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the &lt;a href=&quot;http://www.flightradar24.com/data/flights/fr2631/#7cb28b5&quot; rel=&quot;nofollow&quot;&gt;track of the outbound flight&lt;/a&gt; and compare it to the &lt;a href=&quot;http://www.flightradar24.com/data/flights/fr2630/#7caa45f&quot; rel=&quot;nofollow&quot;&gt;inbound flight&lt;/a&gt; you see that, at least on that occasion, a much longer track was followed. The airline may know that the route back to London is longer (for whatever reason) and adjust expected flight times accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when you compare it to the only other direct flight departing and returning to the same airport (LGW) on skyscanner for the same route, the time difference is much less (15 minutes difference) which is much more usual. It may well be that the route to/from LGW is more equal outbound/return than the route taken to STN. It may also be that this flight in to LGW is at a typically quieter time of day.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-10-26T16:49:58.817" LastActivityDate="2015-10-26T16:49:58.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22387" PostTypeId="2" ParentId="22385" CreationDate="2015-10-26T15:02:51.523" Score="11" Body="&lt;p&gt;Because the priorities for military aircraft (engines) are different. While it is true that the high bypass turbofans have better fuel economy (in cruise) and are less noisy, the low bypass engines offer significant advantages when we take into account their intended use in combat aircraft, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The response of the low bypass turbofans to throttle adjustments is faster compared to the high bypass turbofans; the inertia is less and less air mass is involved (for increasing the velocity)- This is important during combat, when thrust requirements change rapidly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They have less frontal area, reducing the drag produced. For aircraft expected to fly at supersonic speeds, however briefly, this is important.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Better thrust to weight ratio- 6:1 in Trent 1000 Vs 9:1 F119 (used in F-22 Raptor)- Even if the actual thrust produced by the low bypass turbofans is lesser, they produce more thrust per kg of engine, which means that the engine can be more compact in size.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The low bypass turbofans are more efficient at higher speeds compared to the high bypass turbofans.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The lesser size of the low-bypass turbofans mean that the aircraft can be made stealthier by 'burying' the engines in the fuselage, which is all but impossible in case of high bypass turbofans.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-26T15:02:51.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22388" PostTypeId="2" ParentId="21464" CreationDate="2015-10-26T15:40:25.820" Score="5" Body="&lt;p&gt;Jet engines have little mechanical margin, and operate at high temperatures. That means all components expand by more than the mechanical margins when heated. This is no problem when everything expands and contracts together in a controlled fashion. This may be counterintuitive but is easily demonstrated. Cut a circular hole in a metal plate, and heat up the plate. The hole will grow with the same expansion rate as the surrounding material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now what happens if we suddenly stop the fuel flow? The compressive heating of air flowing into the engine doesn't suddenly stop, but all the air flowing through the engine does cool it. This means that the turbine in the back does cool as relatively cool air flows through it. Not only does this cause thermal stresses, but the turbine will shrink.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-10-26T15:40:25.820" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22389" PostTypeId="2" ParentId="22385" CreationDate="2015-10-26T16:04:28.773" Score="27" Body="&lt;h2&gt;It's not military vs civilian, but subsonic vs supersonic-capable&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Note that subsonic military aircraft use the same engines as civilian aircraft, even if their names might be different.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_KC-135_Stratotanker&quot; rel=&quot;noreferrer&quot;&gt;KC-135&lt;/a&gt; used initially the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J57&quot; rel=&quot;noreferrer&quot;&gt;J-57&lt;/a&gt; which was called JT-3C when used in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;noreferrer&quot;&gt;Boeing 707-120&lt;/a&gt;. Now they fly the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;noreferrer&quot;&gt;CFM-56&lt;/a&gt;, which is used on the Boeing 737 and the A320.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-5_Galaxy&quot; rel=&quot;noreferrer&quot;&gt;C-5 Galaxy&lt;/a&gt; uses the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_TF39&quot; rel=&quot;noreferrer&quot;&gt;GE TF39&lt;/a&gt; which became the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_CF6&quot; rel=&quot;noreferrer&quot;&gt;CF6&lt;/a&gt; when mounted to a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;noreferrer&quot;&gt;Boeing 747-100&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10&quot; rel=&quot;noreferrer&quot;&gt;DC-10&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II&quot; rel=&quot;noreferrer&quot;&gt;Fairchild A-10&lt;/a&gt; uses the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_TF34&quot; rel=&quot;noreferrer&quot;&gt;GE TF34&lt;/a&gt; which is called &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_CF34&quot; rel=&quot;noreferrer&quot;&gt;CF34&lt;/a&gt; when mounted to civilian aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_Challenger_600_series&quot; rel=&quot;noreferrer&quot;&gt;Bombardier Challenger&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;No, the differences arise only when the aircraft is designed to fly supersonic. This requires a very different approach to the integration of the engine:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Supersonic aircraft engines are mounted close to the centerline. If possible, they are straight behind the intakes, so the intake flow does not need to change direction. Exceptions like the SR-71 are rare.&lt;/li&gt;&#xA;&lt;li&gt;Supersonic intakes are longer and have sharp edges as opposed to the short, blunt intakes of subsonic aircraft. Also, most have a variable geometry to adapt to the very different flow conditions at supersonic speed.&lt;/li&gt;&#xA;&lt;li&gt;Since it is the job of an intake &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=1%7C0.1187#9222&quot;&gt;to slow down the air going into the engine&lt;/a&gt;, supersonic intakes cannot have a big capture area, or their spill drag in supersonic flight would be excessive. Supersonic engines need to create their thrust with much less airmass than purely subsonic engines. Forget stealth, this is the &lt;strong&gt;real&lt;/strong&gt; reason for the smaller diameters of supersonic-capable engines.&lt;/li&gt;&#xA;&lt;li&gt;The nozzle of a supersonic aircraft is also variable, in contrast to the fixed nozzle of subsonic aircraft. This again helps to adjust it to the flow conditions, but in this case the major difference is between reheat on and off. Afterburning engines are capable of much higher exit speeds to compensate for their smaller diameter. They accelerate less air to a higher speed to create comparable thrust.&lt;/li&gt;&#xA;&lt;li&gt;The last point mentioned it, but it deserves a bullet of its own: Supersonic engines use afterburners in order to have enough thrust for going supersonic at all. The hot exhaust gasses have a much bigger volume than the cold intake flow which needs to be accommodated by widening the nozzle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that the civilian &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; used also a variable intake and nozzle and afterburners. It had an engine which was used on the &lt;a href=&quot;https://en.wikipedia.org/wiki/BAC_TSR-2&quot; rel=&quot;noreferrer&quot;&gt;BAC TSR-2&lt;/a&gt; before, a supersonic military aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real distinction is not between civilian and military, but between purely subsonic and supersonic-capable. Initially, both was achieved with the same engines. The J-57 mentioned above was also used on the supersonic &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot; rel=&quot;noreferrer&quot;&gt;F-100&lt;/a&gt; military jet. Only in the 1960s did those lines diverge, and the subsonic aircraft grew ever bigger low-pressure compressor stages. These were again driven by the high-pressure cores which were used on supersonic aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Background&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Thrust is air mass flow multiplied by the speed difference between flight and nozzle speed of the engine. To increase thrust, subsonic engines try to maximize mass flow (by increasing the bypass ratio) while supersonic engines rely more on increasing the nozzle speed (by using afterburners). Since net thrust is only possible when exit speeds are higher than the flight speed, the engine's exit speed needs to increase with the design flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The core engines do not differ much - after all, the intake will make sure that air reaches the engine &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;at a speed of Mach 0.4 to 0.5&lt;/a&gt;, regardless of flight speed. The core of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_F110&quot; rel=&quot;noreferrer&quot;&gt;General Electric F110&lt;/a&gt; (installed in the F-15 and F-16 fighters, among others) became the core of the CFM-56 turbofan which is used in the Boeing 737 or the Airbus A320. The main difference is in their bypass ratio. The slower the design speed, the bigger the bypass ratio may become. At very low speed, the ungeared, shrouded fan is exchanged for a geared, free spinning propeller, in other words, the jet changes to a turboprop. The intake and nozzle, however, are very different indeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The optimum bypass ratio changes continuously, but since the drag coefficient drops after crossing Mach 1, airplanes are either designed for a maximum Mach number of 0.9 or less, or 1.6 and above. The corresponding bypass ratios today are up to 12 for subsonic engines, and less than 1 for supersonic engines. This produces a sharp boundary at the speed of sound, and many military engines designed for supersonic flight lost their afterburners and were fitted with a big fan to become the engines for subsonic transport aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The differences between sub- and supersonic engines grow bigger the more you move away from their core. High-pressure compressor, combustion chamber and high pressure turbine look and work the same, but the low pressure compressor of subsonic engines swallows a lot more air and has a much bigger diameter. Supersonic engines in turn mostly have an afterburner. The biggest difference, however, are the intakes (large pitot intake with &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730#11730&quot;&gt;blunt lips&lt;/a&gt; for subsonic aircraft versus adjustable &lt;a href=&quot;https://aviation.stackexchange.com/questions/13096/what-are-the-merits-of-an-inlet-cone-spike-centerbody-vs-a-2d-inlet/13109#13109&quot;&gt;spike or ramp intakes&lt;/a&gt; for supersonic flight) and the nozzle (fixed for subsonic flight versus a complex, &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use&quot;&gt;adjustable convergent-divergent nozzle&lt;/a&gt; for supersonic flight). This is due to the very different air speeds and the much higher exit velocities required for supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cdHRp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cdHRp.jpg&quot; alt=&quot;XB-70 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at the intake section of the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;XB-70&lt;/a&gt; pictured above (&lt;a href=&quot;http://jpcolliat.free.fr/ProjetUS/images/xb70_02.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The capture area is rather small, and then the intake tube widens to enable the slowing of the airflow. The inclined sidewalls of the intake section cause &lt;strong&gt;a lot of&lt;/strong&gt; drag at Mach 3. Now think the six &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_YJ93&quot; rel=&quot;noreferrer&quot;&gt;GE YJ-93&lt;/a&gt;s are replaced by engines with an even bigger diameter. The increase in wave drag due to the even blunter intake would cancel out all advantages of a higher bypass ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is less obvious is the fact that this intake section also creates maybe half of the overall thrust of the propulsion system. But this answer is already too long, so I save this for another answer.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-26T20:12:40.630" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22390" PostTypeId="1" AcceptedAnswerId="22391" CreationDate="2015-10-26T16:04:58.970" Score="8" ViewCount="2423" Body="&lt;p&gt;I saw this plane at a warbird fly in and would appreciate some assistance identifying it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only tell you what I'm rather sure it's &lt;em&gt;not&lt;/em&gt;..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;s&gt;Grumman TBF Avenger&lt;/s&gt;&#xA;&lt;br&gt;&#xA;&lt;s&gt;Other US-operated Torpedo Bomber types&lt;/s&gt;&#xA;&lt;br&gt;&#xA;&lt;s&gt;Grumman F4F-3 Wildcat&lt;/s&gt;&#xA;&lt;br&gt;&#xA;&lt;s&gt;Republic P-47 Thunderbolt&lt;/s&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any ideas?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xhyrp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xhyrp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[EDIT]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, is this yellow aircraft the same model, only with a different paint scheme? The nose looks different, but perhaps the cap/cone has been removed, perhaps for maintenance. Otherwise the canopy, wheels, and gear covers look identical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s99pB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s99pB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9850" LastEditorUserId="1858" LastEditDate="2019-11-23T23:03:50.893" LastActivityDate="2019-11-23T23:03:50.893" Title="What kind of WWII aircaft is this?" Tags="&lt;military&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22391" PostTypeId="2" ParentId="22390" CreationDate="2015-10-26T16:09:02.417" Score="10" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_T-6_Texan&quot; rel=&quot;noreferrer&quot;&gt;North American T-6 Texan&lt;/a&gt; Trainer, probably the NJ/SNJ Texan variant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cyLyg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cyLyg.jpg&quot; alt=&quot;SNJ 1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:SNJ-1_at_NAS_Pensacola_c1940.jpeg#/media/File:SNJ-1_at_NAS_Pensacola_c1940.jpeg&quot; rel=&quot;noreferrer&quot;&gt;SNJ-1 at NAS Pensacola c1940&lt;/a&gt;&quot; by U.S. Navy - U.S. Navy National Museum of Naval Aviation photo No. 1996.488.166.090. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The North American Aviation T-6 Texan is a single-engined advanced trainer aircraft used to train pilots of various air forces including (but not limited to) USAAF, USN, RAF from (before) WWII well into the 1970s. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-26T16:21:11.100" LastActivityDate="2015-10-26T16:21:11.100" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22392" PostTypeId="2" ParentId="22381" CreationDate="2015-10-26T18:59:23.173" Score="13" Body="&lt;p&gt;You have two questions here, lets just consider this for GA/commercial planes that are operated mainly from paved strips. Back country flying and grass/dirt strips &lt;a href=&quot;https://en.wikipedia.org/wiki/Tundra_tire&quot; rel=&quot;nofollow noreferrer&quot;&gt;lend to other tire needs&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why are aircraft tyres not grooved horizontally like vehicle tyres?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Short answer, contrary to popular belief groves actually reduce grip. Vehicle tires are also designed to fit a different use case. Summer tires (mainly for dry times) can actually be close to aircraft tires in their cut (full slicks are not legal everywhere). All seasons are made to work well in not only rain but snow and ice as well. As such the groves are cut to displace water as well as provide limited traction on packed snow.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the tyres are grooved horizontally won't it help in achieving more&#xA;  friction and reduce the chances of veering off?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, but lets dig in. There are two cases to consider here, a wet runway and a dry runway. The coefficient of friction of rubber on &lt;a href=&quot;http://www.engineeringtoolbox.com/friction-coefficients-d_778.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;dry asphalt is extremely high&lt;/a&gt; ~=.9 but when it comes to using tires to stop something (breaking really) you want the most rubber/asphalt contact you can get (also known as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Contact_patch&quot; rel=&quot;nofollow noreferrer&quot;&gt;contact patch&lt;/a&gt;). Thus the &quot;grippiest&quot; tire so to speak is whats commonly known as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Racing_slick&quot; rel=&quot;nofollow noreferrer&quot;&gt;racing slick&lt;/a&gt; since there are no groves. By adding tread you actually reduce grip by reducing the contact patch when talking about a dry runway.       &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since airplanes sometimes operate in the wet (let's ignore snow), we need to account for that. To make a tire work well in the wet we need to displace the water so that the rubber can make contact with the asphalt. If you get a layer of water (even a thin film) between the tire and the asphalt you have what is commonly known as &lt;a href=&quot;https://en.wikipedia.org/wiki/Aquaplaning&quot; rel=&quot;nofollow noreferrer&quot;&gt;hydro planing&lt;/a&gt; (no, a seaplane rating won't check you out for this); you can read a &lt;a href=&quot;http://arxiv.org/pdf/cond-mat/0502495.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;full study on it here&lt;/a&gt;. Since you only need to provide area to displace the water to the simple groves provide enough space without adversely affecting grip as a traditinal car tread would.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another somewhat related reason they may not be grooved laterally is to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3702/why-are-aircraft-tires-not-pre-spun-prior-to-landing-to-preserve-them/3705#3705&quot;&gt;prevent the tires from spinning up which could cause other issues&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older F1 Rain tires area actually cut very similar to aircraft tires as can be seen here &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xjnpj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xjnpj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.autoevolution.com/news/why-ayrton-senna-was-brilliant-sam-posey-s-take-video-79617.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare to  this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EyUoh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EyUoh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.airliners.net/photo/South-African-Airways/Airbus-A340-211/1784868/L/&amp;amp;sid=f797f90fef7de7e8d0f33a9bca0175d6&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="753" LastEditDate="2017-11-26T18:10:45.140" LastActivityDate="2017-11-26T18:10:45.140" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22393" PostTypeId="2" ParentId="22381" CreationDate="2015-10-26T20:04:47.640" Score="3" Body="&lt;p&gt;&lt;em&gt;Why are aircraft tires not grooved horizontally?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because, unlike cars where the thrust is a force that acts on the drive wheels, in the point where they touch the ground, and has a forward orientation, the plane is pulled by propellers or pushed by jet engines and the wheels provide no thrust. So, horizontal grooves will not increase the thrust in the case of an aircraft. Even for trucks, the non drive wheels tend to have mainly vertical grooves with some minor horizontal cuts (see the picture).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f7VAZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f7VAZ.png&quot; alt=&quot;http://www.falkentire.com/sites/default/files/content/tires/tire-rotator-images/493x673xRI109_Eco.png.pagespeed.ic.fdQSFQwZvn.png&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding &quot;&lt;em&gt;reducing the chances of veering off&lt;/em&gt;&quot; the best grooves are the vertical ones because they can catch soil and increase the friction in case the plane tends to veer off course while trying to land. Horizontal grooves will have exactly the worst orientation, to the left and right, acting like skates for that direction. &lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-26T22:56:58.980" LastActivityDate="2015-10-26T22:56:58.980" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22394" PostTypeId="2" ParentId="21426" CreationDate="2015-10-26T21:05:00.553" Score="0" Body="&lt;p&gt;espacially harnesses include mechanical, hydraulics, pneumatics and electromechanical parts. Generaly Aileron, elevator, and flaps are controled by hydraulic servos because hydraulics have advantages precision and powerloss, but on landing gear doors are controled by pnuematics(not servos)because you don't need any position feedback you only want to know doors are open or not.&lt;/p&gt;&#xA;" OwnerUserId="12000" LastActivityDate="2015-10-26T21:05:00.553" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22395" PostTypeId="1" AcceptedAnswerId="22420" CreationDate="2015-10-26T21:06:52.780" Score="10" ViewCount="2860" Body="&lt;p&gt;I've noticed this often in flight simulators, and have, to be honest, never paid attention to it in real life, though I'm quite sure it happens there too:&lt;/p&gt;&#xA;&lt;p&gt;When landing gear retracts (and I believe when it extends as well) the two main landing gears don't move simultaneously, but one goes up (down) earlier than the other one.&lt;/p&gt;&#xA;&lt;p&gt;Here is a video that shows this as well: &lt;a href=&quot;https://youtu.be/w4bTPq6qNTs?t=23s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Video&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As a matter of fact it appears one of the flaps that open the landing gear bulk goes down faster? Doesn't that cause aerodynamic disadvantages?&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;There has to be a reason behind that. What reason is this?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="5592" LastEditDate="2020-07-08T12:21:05.283" LastActivityDate="2020-07-08T12:21:05.283" Title="Why does landing gear retract with an offset?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="22396" PostTypeId="1" AcceptedAnswerId="22434" CreationDate="2015-10-26T21:18:47.657" Score="12" ViewCount="1643" Body="&lt;p&gt;What was the first plane that allowed crew members and/or passengers to stand and walk during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P.S.&lt;/strong&gt; I mean walking inside the cabin, as part of normal operation intended for by the plane designers, not walking outside the plane, on wings and other acrobatic activity.&lt;/p&gt;&#xA;" OwnerUserId="4382" LastEditorUserId="4382" LastEditDate="2015-10-27T06:38:18.660" LastActivityDate="2015-10-27T17:11:16.013" Title="What was the first plane that allowed walking during flight?" Tags="&lt;aviation-history&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22397" PostTypeId="2" ParentId="21426" CreationDate="2015-10-26T21:22:47.880" Score="3" Body="&lt;p&gt;Yes of course (I am user12000 by the way :D) pneumatics are fast, cheap, and light but do not have good precision and you have to carry pressurized tanks called reservoirs (that means you need space) and you need to fill your reservoir (that means you need a compressor it means space again). When you compress air it heats up (it means a cooler system which means space again). You can use it again if you don't use it frequently and you want cheap and light. Hydraulics are heavy, expensive, can use high force, and have good precision. You don't need to use a compressor because its uses fluid it needs a pump. Pumps are to smaller than compressors and they produce less heat. You also need a small reservoir (reservoir is needed hydraulics because of protect the system from stress by expansion of fluid because of heat up of system or vice versa).&lt;/p&gt;&#xA;" OwnerUserId="12001" LastEditorUserId="12001" LastEditDate="2015-10-28T09:36:37.193" LastActivityDate="2015-10-28T09:36:37.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22399" PostTypeId="1" CreationDate="2015-10-26T22:19:54.107" Score="7" ViewCount="10269" Body="&lt;p&gt;My understanding of helicopters is that, despite &lt;em&gt;theoretically&lt;/em&gt; increasing efficiency, &lt;a href=&quot;https://aviation.stackexchange.com/a/12381/11671&quot;&gt;longer blades are worse &lt;em&gt;in practice&lt;/em&gt; than short ones&lt;/a&gt; in every respect (except, perhaps, cost):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Longer blades are more prone to vibration and resonance dynamics, if for no reason other than that their rigidity is reduced by length, holding all else constant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Longer blades provide less operating clearance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Longer blades not only stall before shorter blades (retreating), but also hit the Critical Mach number at lower air speeds (advancing).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fewer blades require higher rotational speeds for a given &quot;rotor disk&quot; area, which is inefficient from not only an aerodynamics perspective but also, presumably, a transmission-and-control perspective.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But all helicopters have few blades of significant length.  So: What are the advantages of longer blades, or disadvantages of shorter blades, that lead to the rotor designs in common use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would imagine that in the limit it would be optimal to run something more like a ducted turbine segment, where the swept area is virtually covered in blade surface (i.e., maximizing the number of blades over the swept disc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Noting that in practice blade size seems &lt;em&gt;somewhat&lt;/em&gt; proportional to the body size of the aircraft, I'll deduce that in practice the bulk of the downforce needs to be generated some minimal distance away from the aircraft's body, though with some attention to the body's vertical aerodynamic aspect it seems like that could be reduced.  I guess tilt-rotors could support this hypothesis since their rotors are positioned at a distance from the body &lt;em&gt;and&lt;/em&gt; &lt;a href=&quot;https://aviation.stackexchange.com/q/19364/11671&quot;&gt;they use smaller rotors&lt;/a&gt;, although it seems like they still use blades as large as possible given the wing size and body configuration.&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-03-10T00:39:05.833" Title="Why don't helicopters prefer shorter rotors with more blades?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;rotary-wing&gt;&lt;blade&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ClosedDate="2015-10-27T07:32:28.410" ContentLicense="CC BY-SA 3.0" />
  <row Id="22400" PostTypeId="2" ParentId="22396" CreationDate="2015-10-26T22:41:37.890" Score="5" Body="&lt;p&gt;In the early days (before we made people get up to keep the blood flowing) the only real reason to get up on a plane would have been to go to the bathroom. That being said the first plane with a bathroom was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Caproni_Ca.60&quot; rel=&quot;noreferrer&quot;&gt;Caproni Ca.60 Transaereo&lt;/a&gt; although it crashed on its second flight. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_H.P.42&quot; rel=&quot;noreferrer&quot;&gt;Handley Page H.P.42&lt;/a&gt; is considered the earliest plane to have a toilet built in 1928.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other way to look at this would be to consider the first plane that allowed people to walk around if just to stretch. Early airlines like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Short_Empire&quot; rel=&quot;noreferrer&quot;&gt;Short Empire&lt;/a&gt; 1936, or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_314_Clipper&quot; rel=&quot;noreferrer&quot;&gt;Boeing 314 Clipper&lt;/a&gt; 1938, most likely saw regular walking around on their long flights but these still post date the HP42. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-26T22:41:37.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22402" PostTypeId="1" AcceptedAnswerId="22413" CreationDate="2015-10-26T23:23:56.827" Score="6" ViewCount="1492" Body="&lt;p&gt;As far as I can tell, aviation piston engine power output is typically measured in HP (horsepower).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automotive engine power output is typically measured by running the host vehicle on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamometer&quot;&gt;rolling road, or dyno or dynamometer&lt;/a&gt;.  This directly produces a torque curve, which may be integrated with respect to RPM to provide a power curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously it wouldn't make much sense to put a piston-engined aircraft on such a device.  Instead, how is horsepower measured for aviation piston engines?&lt;/p&gt;&#xA;" OwnerUserId="2797" LastActivityDate="2015-10-27T14:38:02.257" Title="How is horsepower measured for aviation piston engines?" Tags="&lt;piston-engine&gt;&lt;measurement&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22403" PostTypeId="2" ParentId="22396" CreationDate="2015-10-26T23:27:31.967" Score="7" Body="&lt;p&gt;Walking around was always allowed. Allowing passengers to play tennis took more technology:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IeLJX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IeLJX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meals and table service arrived around the same time, 1924, for this Curtiss JN-4:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZOy87.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZOy87.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-10-26T23:27:31.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22407" PostTypeId="2" ParentId="22402" CreationDate="2015-10-27T00:04:18.510" Score="1" Body="&lt;p&gt;&lt;em&gt;How is horsepower measured for aviation piston engines?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One idea is to use a &lt;a href=&quot;http://www.km.kongsberg.com/ks/web/nokbg0240.nsf/AllWeb/ECC998CE82FE3801C125758300448E97?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;&quot;shaft power meter&quot;&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-27T00:04:18.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22408" PostTypeId="2" ParentId="22399" CreationDate="2015-10-27T00:11:26.053" Score="5" Body="&lt;p&gt;The number of (main rotor) blades in a helicopter are dependent on a number of parameters; Usually there are some major issues with having a large number of blades in a helicopter though:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;One main reason is efficiency- In general, lesser the blades, more efficient the system- as it changes the momentum of more air mass i.e. accelerates more air by a lesser amount (akin to the bypass of turbofan engines).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In general, the performance of the helicopter rotor system is affected by &lt;em&gt;solidity&lt;/em&gt; (i.e the ratio of blade area to total disc area) rather than the number of blades.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the number of blades increase, the interaction of subsequent blade with the advancing blade's vortex increase (i.e the blade flies into the preceding blade's wake), which affects the lift produced.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;More blades means more complex rotor hub (more parts usually translate into more problems- maintenance and otherwise) and more interference in the inboard region of the blades. Also, the rotor hub drag is increased.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One thing you're missing is that the blade velocity $V$ (in $L \ = \ \frac{1}{2} \ \rho \ V^{2} \ S$ ) is in itself dependent on the blade length (and rotational speed, through $V \ = \ R\omega$). This means that as the blade length reduces, they have to rotate proportionally faster to produce the same lift- thus in reality, the tip speeds of smaller blades will be more. Usually, the inner third length of a rotor blade contributes very little to lift.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As far as vibration is concerned, (though it is better to have more blades) the whole rotor system has to be taken as a unit rather than as individual blades and the most important consideration is the rotor speed and its harmonics rather than the blade length.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-27T00:11:26.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22409" PostTypeId="1" AcceptedAnswerId="22412" CreationDate="2015-10-27T00:17:44.223" Score="4" ViewCount="2349" Body="&lt;p&gt;Finding a general aviation single-engine piston airplane that's pressurized is a bit rare. What airplanes that meet these specifications have been produced? Also, which ones are still in production?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-10-27T04:38:55.307" Title="What general aviation single-engine piston pressurized airplanes are there?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22410" PostTypeId="2" ParentId="22396" CreationDate="2015-10-27T00:18:46.657" Score="1" Body="&lt;p&gt;&lt;em&gt;What was the first plane that allowed crew members and/or passengers to stand and walk during flight?&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;What I know is that by 1913 people were already standing during flights (see the picture).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XtLP9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XtLP9.jpg&quot; alt=&quot;Russian plane Sikorsky Ilya Muromets ca. 1913&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Russian plane Sikorsky Ilya Muromets ca. 1913&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-27T14:41:54.270" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22411" PostTypeId="1" CreationDate="2015-10-27T00:19:51.057" Score="9" ViewCount="6655" Body="&lt;p&gt;I would think that a pressurized helicopter is impractical since helicopters are usually flying at low altitude, but has a pressurized helicopter ever been conceived or built?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2015-10-27T02:48:35.240" LastActivityDate="2015-10-27T11:25:50.367" Title="Are there any helicopters equipped with pressurized cabins?" Tags="&lt;helicopter&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22412" PostTypeId="2" ParentId="22409" CreationDate="2015-10-27T00:48:19.373" Score="5" Body="&lt;p&gt;The ones I know of &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mooney_M22_Mustang&quot; rel=&quot;nofollow&quot;&gt;Mooney Mustang M22&lt;/a&gt; (out of production)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.piper.com/aircraft/m-class/mirage-2/&quot; rel=&quot;nofollow&quot;&gt;Piper Mirage&lt;/a&gt; (they claim its the only pressurized piston single on the market)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_210&quot; rel=&quot;nofollow&quot;&gt;Cessna P210N&lt;/a&gt; (out of production)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lancair_IV&quot; rel=&quot;nofollow&quot;&gt;Lancair IV-P&lt;/a&gt; (falls under experimental but is in &quot;production&quot; none the less) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For what its worth this is a pretty small category of plane to begin with. The M22 was not very successful (although it was ahead of its time) and there are not that many left flying (less than 20 I think). The P210N saw some better success and the Mirage seems to be selling but in the end of the day extra maintenance and complexity of the plane its self does not lend to a very practical plane considering there size and performance numbers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we are talking about the less produced or experimental designs we can add, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Ju_49&quot; rel=&quot;nofollow&quot;&gt;Junkers Ju 49&lt;/a&gt; - One of the early test beds for pressurization &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Farman_F.1000&quot; rel=&quot;nofollow&quot;&gt;Farman F.1000&lt;/a&gt; - Altitude record plane &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Airco_DH.9A&quot; rel=&quot;nofollow&quot;&gt;Airco DH.9A&lt;/a&gt; - Another early frame used for testing &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-27T04:38:55.307" LastActivityDate="2015-10-27T04:38:55.307" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22413" PostTypeId="2" ParentId="22402" CreationDate="2015-10-27T00:56:58.470" Score="7" Body="&lt;p&gt;Like anything else a &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamometer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dynamometer is used&lt;/a&gt; except the engine is bolted directly to it (&lt;a href=&quot;http://www.nevadaaircraftengines.com/dynometer.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;most likely on a test bench&lt;/a&gt;). In a car a rolling road is simply a way to couple the tires to the dyno without having to have any custom fittings. For what its worth cars lose a bit of horse power in the transmission/drive shaft/differential so shaft horse power and wheel horsepower are not always the same. However in a plane the prop is bolted more or less to the end of the crank (with the exception of some planes with stepper gear boxes). In any case shaft horsepower on a plane engine is more or less whats available at the prop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a lycoming engine on a dyno&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f4Wfh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f4Wfh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.nevadaaircraftengines.com/dynometer.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="7532" LastEditDate="2015-10-27T14:38:02.257" LastActivityDate="2015-10-27T14:38:02.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22414" PostTypeId="2" ParentId="22399" CreationDate="2015-10-27T05:17:50.613" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;The blades of a helicopter are long, narrow airfoils with a high&#xA;  aspect ratio, a shape that minimizes drag from tip vortices (see the&#xA;  wings of a glider for comparison). They generally contain a degree of&#xA;  washout that reduces the lift generated at the tips, where the airflow&#xA;  is fastest and vortex generation would be a significant problem.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Helicopter_rotor&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="19" LastEditDate="2015-10-27T06:47:05.387" LastActivityDate="2015-10-27T06:47:05.387" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22415" PostTypeId="2" ParentId="22399" CreationDate="2015-10-27T06:48:52.890" Score="7" Body="&lt;p&gt;The rotor works by accelerating air downwards, therefore creating an upward reaction force on the blades that lifts the craft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift force is equal to&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L = \dot{m}\Delta v$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\dot{m}$ is mass flow rate through the rotor and $\Delta v$ is the change of speed of the air. To accelerate the air to that speed, it has to give it kinetic energy. This requires power&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$D = \frac12\dot{m}\Delta v^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(the induced drag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now a rotor with &lt;strong&gt;smaller&lt;/strong&gt; diameter will be able to affect &lt;em&gt;less&lt;/em&gt; air, so the $\dot{m}$ will be lower. To produce the same lift, it will need larger $\Delta v$ and therefore it will need more powerful engine (up to a point, because longer blades will have higher form drag that will eventually outweigh the reduction in induced drag) and, more importantly, &lt;strong&gt;burn more fuel&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades, like wings, affect air to a significant distance above and below them, so you don't need many blades to use all air within the rotor area. But no matter how many blades you add, they will still only affect the air within the rotor area, so the efficiency won't change much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as tiltrotors go, they have relatively small rotors and that makes them awfully inefficient in hover. But they don't spend most of their time hovering, they spend most time flying somewhere and in the fixed-wing mode they are faster and more efficient, which outweighs the worse efficiency during take-off and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also: &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power&quot;&gt;Is there any equation to bind velocity, thrust and power?&lt;/a&gt; (via Energizer777's deleted answer).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-10-27T12:54:30.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22419" PostTypeId="2" ParentId="22395" CreationDate="2015-10-27T08:47:25.447" Score="5" Body="&lt;p&gt;As you can see in &lt;a href=&quot;https://youtu.be/w4bTPq6qNTs?t=80s&quot; rel=&quot;noreferrer&quot;&gt;the video&lt;/a&gt;&lt;sup&gt;1&lt;/sup&gt;, they &lt;strong&gt;don't&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least not always. The sequence is the same for both sides and initiated at the same moment for both sides, but sometimes the down- or up-lock takes longer to release than other times, so one or the other side may get some delay. The internal friction in the mechanism may also be different on each side depending on wear of various parts of the assembly, which may add more delay to one or the other side.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Yes, it is the same video, just different part.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-10-27T08:47:25.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22420" PostTypeId="2" ParentId="22395" CreationDate="2015-10-27T10:01:54.740" Score="20" Body="&lt;p&gt;This is called sequencing. The idea is to distribute the high load on the hydraulic system due to retraction over time, so the hydraulic pumps can be smaller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The linked video shows no such sequencing. The triple redundant hydraulic systems on airliners do not need such optimizations since there is plenty of power if all pumps are running. On top, the video was made in a hangar and the pressure source was most likely external, with enough power reserves. Any asymmetries are most likely due to differences in friction, as Jan remarks in his answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since friction losses in the hydraulic lines increase with flow speed, a difference in retraction speed would quickly be equalized, since the faster moving leg needs higher flow speed in the lines leading to and from its actuator, and less pressure would be available for gear operation. Active syncing is not needed, and a small difference has little influence on flight characteristics. After all, the main gear is close to the center of gravity, so drag differences between both legs do not produce big aerodynamic moments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a gear retracts, it first needs to move out of the locks, which requires little hydraulic power. After this, the load gradually increases the more the leg moves up into the horizontal position. Shortly before moving into the final, retracted position the load is highest; the details depend on the gearing of the retraction mechanism. If this load needs to be covered for all three gears at the same time, the hydraulic pump on an aircraft with manual controls and hydraulics only for gear operation would need to be more than twice as large as when you sequence the retraction, so the peak loads come one after the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OxeWg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OxeWg.jpg&quot; alt=&quot;Rockwell 112 with retracting gear&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_Commander_112&quot; rel=&quot;noreferrer&quot;&gt;Rockwell 112&lt;/a&gt; while gear retracts (picture &lt;a href=&quot;http://www.austrianaviationart.org/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Some asymmetry is clearly visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically this is solved with &lt;a href=&quot;http://www.valvehydraulic.info/valve-2/hydraulic-sequencing-valves.html&quot; rel=&quot;noreferrer&quot;&gt;sequencing valves&lt;/a&gt; which serve several circuits. They are used both to time the gear door operation, so the doors open before the gear starts moving, as well as the sequence of the main gears.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-03T08:27:38.583" LastActivityDate="2015-12-03T08:27:38.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22422" PostTypeId="1" CreationDate="2015-10-27T10:38:38.357" Score="2" ViewCount="303" Body="&lt;p&gt;I'm currently in the process of becoming a pilot and the question I keep asking myself is why does it cost so much for just one hour?&lt;/p&gt;&#xA;" OwnerUserId="12008" LastEditorUserId="7532" LastEditDate="2015-10-27T14:28:04.147" LastActivityDate="2015-10-27T14:43:22.653" Title="why does it cost so much just for an hour of training?" Tags="&lt;flight-training&gt;&lt;cost&gt;" AnswerCount="3" CommentCount="4" ClosedDate="2015-10-27T14:21:38.713" ContentLicense="CC BY-SA 3.0" />
  <row Id="22423" PostTypeId="1" CreationDate="2015-10-27T10:54:13.303" Score="0" ViewCount="238" Body="&lt;p&gt;Suppose the pilot or pilots of a plane become incapacitated for whatever reason. At the moment, there is nothing that can be done from the outside to stop it other than to shoot it down (am I right?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it in theory be possible that planes have a 'safe landing' program built in that, at a signal from the ground takes over control? It then does everything necessary to land correctly and automatically at a nearby airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realise I am making a lot of assumptions here. My main question is not about the logistics  of what would have to happen on the ground, nor is it about whether a new generation of terrorists could hack into such a system for their own purposes. It is about how easily current autopilots could be adapted to have a 'land safely' option. What modifications would the manufacturers have to install &lt;em&gt;within the plane itself&lt;/em&gt; that would make this possible?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Summary&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is it true that currently, the only way to control a runaway aircraft is to shoot it down?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In theory could an existing autopilot have a simple interface that is retrofitted such that a single signal from the ground  sets it in 'return to base' mode and produces a safe landing? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9417" LastEditorUserId="9417" LastEditDate="2015-10-27T16:51:27.533" LastActivityDate="2015-10-27T16:52:36.613" Title="Is there any reason in principle that large aircraft couldn't be converted to be controlled remotely?" Tags="&lt;autopilot&gt;" AnswerCount="2" CommentCount="9" ClosedDate="2015-10-27T18:50:30.713" ContentLicense="CC BY-SA 3.0" />
  <row Id="22424" PostTypeId="2" ParentId="22422" CreationDate="2015-10-27T11:13:51.033" Score="4" Body="&lt;p&gt;You've not specified how much you consider &quot;so much&quot;, however it's unlikely to matter too much to the answer. What you're paying for is (at least) twofold, and &lt;em&gt;probably&lt;/em&gt; consists of&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The rental of somebody else's aircraft. Every hour you fly this aircraft takes it an hour closer to an expensive maintenance window. There are costs involved in running an aircraft much like there are costs associated with owning/maintaining any vehicle. Also, fuel isn't free - its is often rolled in to the cost of rental for aircraft.&lt;/li&gt;&#xA;&lt;li&gt;The time of an instructor, who himself has spent time/money learning his craft, and quite possibly does this as his job (as in, its his sole purpose to earn money from teaching you to fly). He has skill and experience, and like all jobs, the more his skill/experience the greater fees he can charge.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;You may have missed the first rule of purchasing a service - shop around. Is your flight school/instructor of a comparable price to others in the locality? Is the instructor you're using a senior CFI, or a new CPL hour-building to get a job with an airline? You will potentially get a different level of service depending on price, but this may suit your wallet better while still giving you the skills you need to get your own pilots license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anectote: When I was training for my PPL (circa 2001-2002) in the UK I paid roughly £150/hr. This included the hire of a C152 and a pretty experienced instructor. From memory the instructor was £80/hr and the remainder was the aircraft. When I got sick of being cramped in a C152 with another 6'2&quot; guy, I paid more to fly a C172 - probably added about £40/hr to the cost. &lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-10-27T11:20:08.807" LastActivityDate="2015-10-27T11:20:08.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22425" PostTypeId="2" ParentId="22411" CreationDate="2015-10-27T11:25:50.367" Score="11" Body="&lt;p&gt;Helicopter cabins are not usually pressurized as they are not expected to be operated at high altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The largest operational helicopter, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-26&quot;&gt;Mil Mi 26 Halo&lt;/a&gt; has a pressurized crew cabin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Russian &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-24&quot;&gt;Mil Mi-24 Hind&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Mil_Mi-28&quot;&gt;Mil Mi 28 Havoc&lt;/a&gt; feature pressurized cockpits. However, these are for operating in an NBC environment, not for high altitude operation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-27T11:25:50.367" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22426" PostTypeId="2" ParentId="22423" CreationDate="2015-10-27T12:12:53.737" Score="3" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes for reasons of hacking prevention. There is no way to be absolutely sure any interface can't be hacked to crash the plane remotely into a suburb.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes autopilots can follow a track of navigation marks to an airfield and can auto-land using the ILS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But again there is no way to ensure only signals from people who have the best intentions with the plane can activate that mode.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-10-27T12:12:53.737" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22427" PostTypeId="1" AcceptedAnswerId="22430" CreationDate="2015-10-27T12:51:32.187" Score="33" ViewCount="9070" Body="&lt;p&gt;I've read enough crash reports to see that helicopters discovering too late in takeoff that they lack the power to fly out of ground-effect is a serious problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering why the following isn't standard takeoff practice: Establish positive climb rate &lt;em&gt;out of ground effect&lt;/em&gt; before beginning any translational flight.  Failure to climb out of ground effect would be cause for immediate ATO, and there would be this nice landing zone to abort into!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Only in exceptional emergencies, like when a mountain takeoff gives the rotor-craft a clear glide-path into denser air, would it be reasonable to ignore this procedure.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I note that I am assuming that translational flight out of ground effect is always more demanding than hovering.  I vaguely remember that this is &lt;em&gt;not&lt;/em&gt; the case, but I don't remember why, and it seems counterintuitive since translational motion always establishes a retreating blade with lower lift that then needs a higher angle-of-attack and more power to maintain lift.  So if the helicopter can't climb under full power with no translation, it would not be able to once it tries moving forward.)&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="11671" LastEditDate="2015-10-27T22:41:03.047" LastActivityDate="2021-03-31T19:00:47.883" Title="Why don't helicopters always takeoff from a hover out of ground-effect?" Tags="&lt;takeoff&gt;&lt;helicopter&gt;&lt;ground-effect&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22428" PostTypeId="2" ParentId="22377" CreationDate="2015-10-27T12:53:11.927" Score="1" Body="&lt;p&gt;The pilot ejects last so that he/she can attempt to remain in control of the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="12010" LastActivityDate="2015-10-27T12:53:11.927" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22429" PostTypeId="2" ParentId="22422" CreationDate="2015-10-27T12:56:11.723" Score="1" Body="&lt;ul&gt;&#xA;&lt;li&gt;Depreciation cost of the aircraft &lt;/li&gt;&#xA;&lt;li&gt;Planned and unplanned maintenance&lt;/li&gt;&#xA;&lt;li&gt;Insurance &lt;/li&gt;&#xA;&lt;li&gt;Organisation fixed and variable costs (offices, admin&#xA;personnel, stationery etc) &lt;/li&gt;&#xA;&lt;li&gt;Aircraft utilisation (hours you can sell vs hours available)&lt;/li&gt;&#xA;&lt;li&gt;Fuel and oils &lt;/li&gt;&#xA;&lt;li&gt;Instructor hourly rate&lt;/li&gt;&#xA;&lt;li&gt;Service fees paid to the local airfield where the aircraft lives&lt;/li&gt;&#xA;&lt;li&gt;Hangarage&lt;/li&gt;&#xA;&lt;li&gt;Profit&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's amazing that I can do this locally for about $250 per hour.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-10-27T13:32:31.730" LastActivityDate="2015-10-27T13:32:31.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22430" PostTypeId="2" ParentId="22427" CreationDate="2015-10-27T13:10:57.090" Score="41" Body="&lt;p&gt;Forward flight is much more efficient than hovering.  As airspeed builds, lift increases from &quot;translational&quot; lift as the air moves more horizontally over the disc.  Since the relative airflow is more horizontal, the angle of attack for a given pitch angle is increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vortices and turbulence move behind and down from the helicopter so undisturbed air is drawn over the disc to be accelerated downwards to produce lift.  Lift is more efficiently produced by accelerating a large mass by a small amount rather than a small mass by a large amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is more efficient to remain in ground effect and slowly increase speed to gain translational lift than to increase power to HOGE (Hover Out of Ground Effect) and attempt to translate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problems you refer to are where an unwary pilot attempts to transition from HOGE whilst allowing the aircraft to climb or attempting to maintain height.  Without enough power, the loss of ground effect before the benefits of translational lift are gained will result in a rapid descent back to earth (as vortex ring state or settling with power is pretty much impossible to avoid) or you overpitch and drag the RRPM (rotor RPM) down so low that you cannot produce lift or even worse, stall the blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line, it takes more power to establish positive climb out of ground effect than to gain translational lift in ground effect.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-09T14:09:10.067" LastActivityDate="2015-11-09T14:09:10.067" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22431" PostTypeId="2" ParentId="22422" CreationDate="2015-10-27T13:26:27.880" Score="3" Body="&lt;p&gt;Here is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/77/what-are-the-typical-facets-of-ownership-costs-for-a-single-engine-aircraft&quot;&gt;nice answer that covers the various costs of owning an aircraft&lt;/a&gt; and will give you a good idea of what goes into it. The only additional thing that a rental plane needs (here in the US under FAA regs) is a 100 hour inspection while private planes only need an annual. Generally speaking rental planes also tend to get fixed pretty quickly as the school does not want or cant afford to have them out of service for very long. Both the flight schools I have been at had their own maintenance hangers and mechanics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the costs are quite variable even in a given area. I used to fly out of KPNE and rent a warrior at 130(USD)/Hour wet, that flight school closed and I am now up at &lt;a href=&quot;http://www.doylestownairport.com/Rental-Fleet/Piper-Cherokee-Warrior-N9280A.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;KDYL renting&lt;/a&gt; the same plane for 108(USD)/Hour wet. Both flight schools charge 40(USD)/Hour for the instructor. Compare this to the other airport in the area &lt;a href=&quot;http://flyadvanced.com/fly/fleet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wings Field&lt;/a&gt; which has a brand new fleet of Cirrsus' renting for around 300(USD)/Hour wet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On any note the Flight schools usually have to &lt;a href=&quot;https://aviation.stackexchange.com/questions/77/what-are-the-typical-facets-of-ownership-costs-for-a-single-engine-aircraft&quot;&gt;cover the costs of owning the plane&lt;/a&gt; as well as make a profit. Its also wise to work in some flex to that since planes do break and are often costly to fix even the simple things. Flight schools typically also need to cover the costs of owning what ever building they operate out of as well as paying anyone that is not a flight instructor that works there.        &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-10-27T14:43:22.653" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22432" PostTypeId="1" AcceptedAnswerId="22435" CreationDate="2015-10-27T14:32:32.913" Score="2" ViewCount="557" Body="&lt;p&gt;Let's say that a package has to travel from point A to point B. These places are not located in the same Country, nor are such Countries adjacent to each other. Example: point A is in Italy, point B is in the United Kingdom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The package is not delivered directly. From tracking info made available by the Company, you find out the package leaves point A and reaches Rome. Then it reaches Bologna, and later Dusseldorf, Germany. It then reaches Barking, in the United Kingdom. From here, it reaches Tamworth and then gets delivered to point B. These legs are pretty short, if you map them, so my question is: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;could the package have traveled by air in any of such legs? or do Cargo companies prefer other means in this situation?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not referring to the use of wide body aircraft on short-haul. Rather, I want to figure out if contracting out the delivery of goods over short-haul routes is a common practice among Cargo airlines. If this is true, how could a given package remain within the network of the Company?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="11885" LastEditDate="2015-10-27T14:54:45.267" LastActivityDate="2015-10-27T17:45:45.403" Title="Do Cargo fly very short routes?" Tags="&lt;cargo&gt;&lt;flight-path&gt;&lt;flight-schedules&gt;" AnswerCount="2" CommentCount="8" ClosedDate="2015-10-27T18:46:46.630" ContentLicense="CC BY-SA 3.0" />
  <row Id="22434" PostTypeId="2" ParentId="22396" CreationDate="2015-10-27T15:43:47.050" Score="11" Body="&lt;p&gt;The first airplane with a cabin big enough for walking around was indeed a Sikorsky. This was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_Russky_Vityaz&quot; rel=&quot;noreferrer&quot;&gt;Sikorsky Russky Vityas&lt;/a&gt;, also sometimes named &quot;Le Grand&quot;, a name which was given to an earlier, two-engined version. Oh, and the cabin included a washroom, too!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9l7KR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9l7KR.jpg&quot; alt=&quot;Sikorsky Le Grand&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sikorsky Russky Vityas (picture &lt;a href=&quot;https://de.wikipedia.org/wiki/Russki_Witjas#/media/File:Sikorsky_Russky_Vityaz_(Le_Grand).jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was the first four-engined airplane in the world and the biggest airplane of its time. It flew first on May 10 (or 13, depending on the source), 1913.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quote from Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After the Russky Vityaz's first test flights between 10 and 27 May&#xA;  1913 (Old Style dates), it was established that a passenger could even&#xA;  walk around the cabins without causing any problems to stability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hrFBg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hrFBg.jpg&quot; alt=&quot;Early Le Grand version&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early Le Grand version with two engines (&lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_Russky_Vityaz#/media/File:Sikorsky-LeGrand.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-27T17:11:16.013" LastActivityDate="2015-10-27T17:11:16.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22435" PostTypeId="2" ParentId="22432" CreationDate="2015-10-27T16:00:15.953" Score="4" Body="&lt;p&gt;It's fairly common for cargo, freight, and mail to be carried by aircraft - particularly for high value or priority cargo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example Royal Mail (the primary British mail service) uses short haul flights for distances of less than 100 miles (London Stansted to East Midlands Airport), along with around another 10 flights within the UK, every night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These flights are used for priority (next day) mail, but will be filled with &quot;cheaper&quot; mail if necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It all depends on the value of the cargo and the speed which it needs to travel, and aircraft only tend to be used where it is profitable to do so (ie where the cargo needs to travel fairly quickly and they can charge a high price to justify that).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally trucks will be used for shorter distances (&amp;lt;500 miles) for low value cargo, and for longer distances for heavier cargo or cargo which does not need to travel quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.eastmidlandsairport.com/emacargo.nsf/content/customer_royalmail&quot; rel=&quot;nofollow&quot;&gt;http://www.eastmidlandsairport.com/emacargo.nsf/content/customer_royalmail&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Royal_Mail#Fleet&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Royal_Mail#Fleet&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-10-27T16:00:15.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22436" PostTypeId="2" ParentId="22423" CreationDate="2015-10-27T16:52:36.613" Score="0" Body="&lt;p&gt;In principle, no. But there are problems in practice.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It is true that at present, the only way to &lt;em&gt;stop&lt;/em&gt; a runaway aircraft is to shoot it down (unless there is some way of getting into the cockpit, like in movies).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Modern aircraft (at-least the most recent ones) are programmed (via their fly-by-wire computers) to land automatically without any human interference (except for setting flaps etc., as already noted) and these can be programmed to do a landing on command. However, whether they can be used in practice is different altogether:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The autopilot landing is instrumented and is not possible in all the airports. The computer has to 'decide' where to land based on fuel situation, among other things.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What will happen if the runway contaminated? or one of the tires blow during touchdown? If the crosswind is more than what the autopilot is designed for? There are too many variables and in most cases it will do more harm than good.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;And most importantly, what if the signal is sent by by someone intending to crash the aircraft? what if some one sends the signal (even accidentally) during takeoff? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Adding auto-land on remote command is more trouble than its worth.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-27T16:52:36.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22438" PostTypeId="2" ParentId="22432" CreationDate="2015-10-27T17:45:45.403" Score="2" Body="&lt;p&gt;In your example it depends on the service. Since UPS is mostly a ground service company it will almost always move by ground transportation. The only time they would move it by air is if the shipment is air service and has a sooner delivery commitment. Moving freight by aircraft is always going to be more expensive than putting it on a truck or a train. If they can make their delivery commitment without flying it they will. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the shipment is moved through air service then it is more likely to move by aircraft. In this case it depends not only on distance but location within the system. If the origin and destination are both within the same &quot;market&quot;, I.e. serviced from the same airport, then there will be no reason for it to go on a plane. Outside the market    anything that has an overnight delivery commitment will go on an aircraft to a hub where it will be sorted and flown to the airport that services the destination. In situations where there are numerous large markets in very close proximity, such as the US east coast, they may be able to accomplish this by ground transport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With regular mail often government postal systems will have a certain amount of space allotted for them on commercial aircraft, both freight and passenger. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-27T17:45:45.403" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22439" PostTypeId="1" AcceptedAnswerId="22446" CreationDate="2015-10-27T18:13:39.993" Score="5" ViewCount="212" Body="&lt;p&gt;What are the weaknesses of Active thermal imaging in NDI of different composite materials used in aircraft structure ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much time and effort does it take to complete a full structure inspection with the latest portable equipment like &lt;a href=&quot;http://www.c-checkir.com/&quot; rel=&quot;nofollow&quot;&gt;(C-CheckIR)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12014" LastEditorUserId="12014" LastEditDate="2015-10-29T06:24:00.807" LastActivityDate="2015-12-03T16:20:08.740" Title="Does Active Thermal Imaging (NDI method) detect all types of structural faults in modern civil aircraft?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22440" PostTypeId="2" ParentId="22377" CreationDate="2015-10-27T20:17:48.283" Score="2" Body="&lt;p&gt;I'd think the main reason would be to avoid cooking the rear seat crew while the rockets were firing as well as to avoid an accidental collision between the front seat and the rear seat crew. After all - the jet is likely to be travelling forward at a relatively high velocity when the two are coming out of the plane (or what's left of it).&lt;/p&gt;&#xA;" OwnerUserId="12018" LastActivityDate="2015-10-27T20:17:48.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22441" PostTypeId="1" CreationDate="2015-10-27T21:00:44.013" Score="2" ViewCount="1763" Body="&lt;p&gt;Is there an exportable public database that I may get a copy of all navigational fixes and their corresponding GPS coordinates (latitude, longitude)? &#xA;p.s. Only US airspace navigation fix information is needed.  &lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="595" LastEditDate="2015-10-28T06:34:48.293" LastActivityDate="2015-10-28T06:34:48.293" Title="Where can I download the coordinates of navigation fixes/intersections?" Tags="&lt;navigation&gt;&lt;gnss&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2015-10-27T22:54:45.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="22442" PostTypeId="2" ParentId="22441" CreationDate="2015-10-27T21:07:57.177" Score="0" Body="&lt;p&gt;The closest I can think of would be the &lt;a href=&quot;https://www.navigraph.com/fmsdata.aspx&quot; rel=&quot;nofollow&quot;&gt;Navigraph FMS data&lt;/a&gt;, however this is provided in multiple formats. Otherwise you can use &lt;a href=&quot;http://skyvector.com&quot; rel=&quot;nofollow&quot;&gt;Skyvector&lt;/a&gt; to look at them graphically.&lt;/p&gt;&#xA;" OwnerUserId="12013" LastActivityDate="2015-10-27T21:07:57.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22443" PostTypeId="1" AcceptedAnswerId="22470" CreationDate="2015-10-27T21:50:41.073" Score="2" ViewCount="2132" Body="&lt;p&gt;What are the intervals at which a full structure inspection take place ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much time does a test commonly take for narrow and wide body aircraft ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is every part in the structure manually inspected by the operator in level C Check or some parts only depending on the Structure repair manual (SRM) of the aircraft? &lt;/p&gt;&#xA;" OwnerUserId="12014" LastEditorUserId="8730" LastEditDate="2015-10-28T16:46:34.550" LastActivityDate="2015-10-28T18:00:47.290" Title="How does a full fuselage and structure inspection happen in practice ? (for modern Civil airliners)" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-structures&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22444" PostTypeId="5" CreationDate="2015-10-27T22:44:15.763" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-10-27T22:44:15.763" LastActivityDate="2015-10-27T22:44:15.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22445" PostTypeId="4" CreationDate="2015-10-27T22:44:15.763" Score="0" Body="The increase in lift experienced by wings in close proximity to the ground." OwnerUserId="11671" LastEditorUserId="11671" LastEditDate="2015-10-27T23:15:32.400" LastActivityDate="2015-10-27T23:15:32.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22446" PostTypeId="2" ParentId="22439" CreationDate="2015-10-27T23:22:13.207" Score="7" Body="&lt;p&gt;No. There is no single NDT method that can identify all types of structural faults in the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Active thermography refers to the use of (thermal) exciters like ultrasound, (halogen and xenon) lamps, eddy current transducers and detecting the defects using that fact that the heat produced is different in those areas, usually using infrared cameras.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though this is a very effective method for detecting defects, especially in composites, there are some disadvantages as well.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The test specimen has to be 'hooked up' to some form of (thermal) loading device. This limits the size of the tested part. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;This is an excellent method for detecting subsurface defects; however, as the depth of the defect increases, the defect size has to be larger for detection. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The method requires that the temperature of the region (containing the defect) be uniform. This is a problem especially for materials with high thermal diffusivity like metals, which may require high speed IR cameras.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Though automated algorithms are available for defect detection, most of the (older) methods of thermography depend on the operator for interpretation of results.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The type of excitation technique used can be limited in some cases to prevent damage to the tested part.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-03T16:20:08.740" LastActivityDate="2015-12-03T16:20:08.740" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22447" PostTypeId="1" CreationDate="2015-10-27T23:25:41.543" Score="4" ViewCount="934" Body="&lt;p&gt;I have tried to calculate the efficiency of Gustave Whitehead's propellers using the information he provided to the American Inventor Magazine in 1902 (see the citation below).&lt;/p&gt;&#xA;&lt;p&gt;Number of propellers = 2&lt;/p&gt;&#xA;&lt;p&gt;Engine power per propeller, &lt;span class=&quot;math-container&quot;&gt;$P$&lt;/span&gt; = 20 hp&lt;/p&gt;&#xA;&lt;p&gt;Propeller diameter, &lt;span class=&quot;math-container&quot;&gt;$D$&lt;/span&gt; = 6 ft&lt;/p&gt;&#xA;&lt;p&gt;Static thrust per propeller, &lt;span class=&quot;math-container&quot;&gt;$T$&lt;/span&gt; = 254 lbf&lt;/p&gt;&#xA;&lt;p&gt;Propeller efficiency, &lt;span class=&quot;math-container&quot;&gt;$\eta_{prop}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Gear efficiency, &lt;span class=&quot;math-container&quot;&gt;$\eta_{gears}$&lt;/span&gt; &amp;lt; 100%&lt;/p&gt;&#xA;&lt;p&gt;Air density, &lt;span class=&quot;math-container&quot;&gt;$\rho=1.2 \frac{kg}{m^3}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Doing the calculations: &lt;span class=&quot;math-container&quot;&gt;$\eta_{prop} &amp;gt; \sqrt{\frac{T^3}{(P^2 \cdot \pi \cdot \eta_{gears} \cdot \frac{D^2}{2} \cdot \rho )}} = 101.4\%$&lt;/span&gt; which is impossible.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Is there a mistake? If yes, where?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Note: I used &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;the formula that relates static thrust to efficiency, power and propeller diameter&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;The Whitehead Flying Machine&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Has the End been Finally Attained, and is the Dirigible Balloon to Go?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Editor, American Inventor&lt;/p&gt;&#xA;&lt;p&gt;Dear Sir: Replying to your recent letter, I take pleasure in sending you the following description of my flying machine No. 22, the latest that I have constructed:&lt;/p&gt;&#xA;&lt;p&gt;This machine was built in four months with the aid of 14 skilled mechanics and cost about $1,700 to build. It is run by a &lt;strong&gt;40 horse-power&lt;/strong&gt; kerosene motor of my own design, especially constructed for strength, power and lightness, weighing but 120 pounds complete. It will run for a week at a time if required, without running hot, stopping, or in any possible manner troubling the operator. No electrical apparatus is required for ignition purposes. Ignition is accomplished by its own heat and compression; it runs about 800 revolutions per minute, has five cylinders and no fly-wheel is used. It requires a space 10 inches wide, 4 feet long and 10 inches high. ...&lt;/p&gt;&#xA;&lt;p&gt;The propellers are &lt;strong&gt;6 feet in diameter&lt;/strong&gt; and have a projecting blade-surface of 4 square feet each. They are made of wood and are covered with very thin aluminum sheeting. The propellers run about 600 revolutions per minute under full power and turn in opposite directions. When running at full speed they will exert a &lt;strong&gt;thrust of 508 pounds&lt;/strong&gt;. I measured this thrust by attaching the machine to a post by means of a dynamometer and running the engines at full speed. ...&lt;/p&gt;&#xA;&lt;p&gt;I have no photographs taken yet of No. 22, but send you some of No. 21, as these machines are exactly alike, except the details mentioned. No. 21 has made four trips, the longest one and a half miles, on August 14, 1901.   The wings of both machines measure 30 feet from tip to tip, and the length of the entire machine is 32 feet.   It will run on the ground 50 miles an hour, and in air travel at about 70 miles.  I believe that if wanted it would fly 100 miles an hour. The power carried is considerably more than necessary. ...&lt;/p&gt;&#xA;&lt;p&gt;Trusting this will interest your readers, I remain, Very truly yours,&lt;/p&gt;&#xA;&lt;p&gt;GUSTAVE WHITEHEAD&#xA;Bridgeport, Conn.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.wright-brothers.org/History_Wing/History_of_the_Airplane/Who_Was_First/Gustav_Whitehead/Whitehead_Articles.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;The American Inventor Magazine&#xA;, 1 April 1902&#xA;&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2021-03-16T18:10:27.967" Title="Why does this calculation show Gustave Whitehead's propellers were more than 100% efficient?" Tags="&lt;aviation-history&gt;&lt;propeller&gt;" AnswerCount="5" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22449" PostTypeId="1" AcceptedAnswerId="22457" CreationDate="2015-10-28T00:06:00.227" Score="1" ViewCount="958" Body="&lt;p&gt;Say a passenger jet lands in the ocean. Could the captain being the last person to get off the jet use the drop down dry chemical oxygen generators to breathe while checking for passengers? I know they are flimsier so depending on depth they would collapse. &lt;/p&gt;&#xA;" OwnerUserId="11761" LastEditorUserId="39" LastEditDate="2015-10-28T06:22:02.913" LastActivityDate="2015-10-28T12:57:02.373" Title="Can you breathe with a drop down mask under water?" Tags="&lt;landing&gt;&lt;oxygen-mask&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22450" PostTypeId="2" ParentId="22443" CreationDate="2015-10-28T00:17:47.130" Score="1" Body="&lt;p&gt;The inspection schedule of each aircraft is decide by the manufacturer in coordination with the regulatory authorities and released to the customer and varies from aircraft to aircraft. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of civil aircraft, 'full' inspection, usually called the D-level checks, is carried out every 4-5 years.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It depends on the aircraft condition and factors like aircraft age, how it was maintained etc. it is time consuming, usually taking a few months depending on the replacement requirements and resources (like no. of technicians available).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The structure is thoroughly inspected- Every single part is subjected to checks in addition to any checks mandated by regulatory authorities/manufacturer or required by customer.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-28T00:17:47.130" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22451" PostTypeId="2" ParentId="22447" CreationDate="2015-10-28T01:38:48.803" Score="5" Body="&lt;p&gt;The equation you referenced shows prop diameter squared, divided by 2, not 4.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even then, the calculation shows that marketing is to experimentation as about 2:1 :) &lt;/p&gt;&#xA;" OwnerUserId="11572" LastActivityDate="2015-10-28T01:38:48.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22453" PostTypeId="2" ParentId="22449" CreationDate="2015-10-28T04:54:49.910" Score="1" Body="&lt;p&gt;It is a chemical reaction. So yes, if contained it could provide oxygen under water (provided the reaction did not react with the water). However, it would not work for the reasons already mentioned in the comments and the infeasible logistics of a hollywood captain single-handedly saving his passengers at the last second ;-)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Emergency_oxygen_system#Mechanism&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Emergency_oxygen_system#Mechanism&lt;/a&gt;&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Chemical_oxygen_generator&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Chemical_oxygen_generator&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11969" LastActivityDate="2015-10-28T04:54:49.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22454" PostTypeId="2" ParentId="311" CreationDate="2015-10-28T05:04:23.677" Score="0" Body="&lt;p&gt;The wing pushes air down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight, that air pushes on other air that moves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ground effect, that air pushes on the ground that doesnt move.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pushing things that move is more difficult than pushing things that dont move. Like walking on sand vs walking on pavement.&lt;/p&gt;&#xA;" OwnerUserId="11969" LastActivityDate="2015-10-28T05:04:23.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22455" PostTypeId="1" CreationDate="2015-10-28T08:46:08.493" Score="2" ViewCount="186" Body="&lt;p&gt;If an already existing fleet (737-800 and 900 without winglets) is thinking of a winglet modification, is that possible without regulations? Or what are the regulations?&lt;/p&gt;&#xA;" OwnerUserId="12024" LastActivityDate="2015-10-28T11:45:53.437" Title="Are there winglet modification regulations?" Tags="&lt;regulations&gt;&lt;winglets&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22456" PostTypeId="1" CreationDate="2015-10-28T10:25:35.060" Score="2" ViewCount="1156" Body="&lt;p&gt;Here are few facts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A flight is basically climbing, staying high, then descending toward a runway&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Changes in altitude increase the distance an aircraft flies. Given the climb/descent angle, this increase may be insignificant, but it still exists. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The path followed by an airliner &lt;a href=&quot;https://aviation.stackexchange.com/questions/13428/why-dont-airlines-fly-a-great-circle-route-between-barcelona-and-d%C3%BCsseldorf?&quot;&gt;may not be direct&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Given many elements (TSA, other traffic,...) I imagine an airliner can almost never take a direct route. Not to mention the path leading to the approach.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An airport may have several runways whose length may not be the same&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The departure point may be the parking position, the beginning of the runway, the end of the runway, the point where the aircraft reaches $V_2$,...&#xA;The same goes for the arriving point.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The precision of the maximum range of an aircraft is really precise&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When looking at ailiners' performances, one key figure seems quite strange: the &lt;a href=&quot;https://aviation.stackexchange.com/questions/tagged/range&quot;&gt;range&lt;/a&gt;. It seems quite precise (few miles). Lets take the &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_ERJ_145_family#Specifications&quot; rel=&quot;nofollow noreferrer&quot;&gt;ERJ-140ER&lt;/a&gt; as example. Its maximum range is 1250nm. Given this number, I imagine the precision is less than 10nm (3 significant digit), i.e. about 3 to 4 times an international airport's runway length (4km for &lt;a href=&quot;https://en.wikipedia.org/wiki/Dubai_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;dubai international airport&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given all those elements, how is a leg length (distance of 1 flight between 2 airports) calculated for an airliner?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-01-30T22:44:42.043" Title="How is the length of a leg calculated?" Tags="&lt;airliner&gt;&lt;airport&gt;&lt;range&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22457" PostTypeId="2" ParentId="22449" CreationDate="2015-10-28T10:46:12.297" Score="10" Body="&lt;p&gt;No, you cannot - at least not with the default masks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In principle, the oxygen systems on board can all provide at least 15 mins. of oxygen, in some of the worst conditions (indeed, that's what they're designed to do). However, their sole purpose is to make high altitude air breathable. The key principle here is &lt;strong&gt;partial pressure&lt;/strong&gt;. Basically, the partial pressure of a gas is the fraction of a certain gas in a gas mixture times the ambient pressure. Since normal air consists of about 21% oxygen, the partial pressure of oxygen at sea level is 0.21 atm (atmosphere). If the partial pressure of oxygen is too low, your lungs actually lose oxygen to the atmosphere when you breathe - much like a deflating balloon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the cabin pressure drops, the partial pressure of oxygen drops proportionally. In that case, oxygen masks are provided. They do not raise the pressure of the air you breathe in, but raise the partial pressure of oxygen by filling your mask with oxygen. If the cabin pressure would drop to 0.2 atm, and you would be given 100% oxygen, the partial pressure of oxygen would be 0.2atm, which is about the same as at sea level - perfectly survivable. The mask as such &lt;strong&gt;does not need to be airtight&lt;/strong&gt; - it just needs to make sure that there's enough oxygen flowing into your mask to displace all the useless nitrogen in the air. Indeed, the mask you will see on airplanes are generally flimsy, plastic masks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under water, these masks are not sufficient at all. They will probably turn into a frothy, bubbly mess of a water/oxygen mixture, especially when the aircraft is filling up with water, due to strong currents. So, you would have to wait for the currents to diminish, and then hold your oxygen mask in such a way that no water will enter it - this probably means you will have to face upwards all the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, you can get creative (pull the mask of and breathe from the tube), or luck out with a high quality mask that happens to work underwater. But I'm afraid that as soon as your plane is sinking, it's too late to play the hero, and your best bet would be to get out and at least save your own life.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="5517" LastEditDate="2015-10-28T12:57:02.373" LastActivityDate="2015-10-28T12:57:02.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22458" PostTypeId="2" ParentId="22449" CreationDate="2015-10-28T11:00:33.790" Score="1" Body="&lt;p&gt;It depends on how much oxygen is provided by the mask, i.e. what the flow rate is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess masks for pilots should be independent from ambient air at any altitude for the case that there's smoke in the cockpit. &#xA;So yes, they would provide enough air for breathing at sea level, or even slightly under water. But those masks are in the cockpit and not mobile.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oxygen masks for passengers don't provide all the air they breathe, they just add some oxygen to the ambient air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have a look at this diagram, which shows which fraction of oxygen in air at certain altitudes correspond to which at sea level:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vzjkb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vzjkb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;em&gt;(This uses the given percentages and the simple common barometric formula, other sources may show other curves)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be fine if passengers are kept somewhere in the yellow region, as e.g. drowsiness wouldn't matter for them, just sitting around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At an altitude of about 12km/ 40,000ft, the passengers should get air with maybe 50% oxygen, 20% from the ambient, 30% from the mask.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, imagine you are under water and try to breathe from the oxygen masks only. You will have to cut off the mask and breathe from the tube. The flow rate from this pipe is just 30% of the usual flow rate, so you have to breathe very slowly. This will be a problem, though the amount of oxygen from the tube would be fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Physical stress like diving through the aircraft and pulling out passengers would increase the need for oxygen drastically and then, even the pure oxygen from the tubes would not be enough.&#xA;You may put several tubes into your mouth, if you manage to do that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, the gas flow from chemical oxygen generators decreases after activation, and comes to rest after a few minutes, so this wouldn't work if the masks were already deployed at high altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know about the mobile oxygen devices for the crew. If they allow to breathe independent from ambient air, they would work under water. But I guess, they also only enrich the air with oxygen, may be more than the passenger's masks.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2015-10-28T11:00:33.790" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22460" PostTypeId="2" ParentId="22449" CreationDate="2015-10-28T11:33:49.333" Score="0" Body="&lt;p&gt;In addition to the discussion of the physical ability to use the mask to deliver oxygen under water - it is worth noting that breathing pure oxygen in a high pressure environment results in &lt;a href=&quot;http://www.lakesidepress.com/pulmonary/books/scuba/gaspress.htm&quot; rel=&quot;nofollow&quot;&gt;oxygen toxicity&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, oxygen at high concentrations is increasingly poisonous to our nervous system and pulmonary system as atmospheric pressure increases. This makes your example question an even more terrifying prospect if the aircraft is sinking rapidly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if faced with the choice of drowning or rolling the dice with toxicity, I guess I'd try the mask...&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2015-10-28T12:18:54.470" LastActivityDate="2015-10-28T12:18:54.470" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22461" PostTypeId="2" ParentId="22455" CreationDate="2015-10-28T11:45:53.437" Score="1" Body="&lt;p&gt;In the U.S., changing anything on the wing is considered to be a &quot;Major Repair/Alteration&quot; according to the FAA (&lt;strong&gt;FAR Part 43 - Appendix A&lt;/strong&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make those changes, this form - &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Form/Form_337.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/documentLibrary/media/Form/Form_337.pdf&lt;/a&gt; needs to be completed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, it requires a certified mechanic to handle the work after which a person with &lt;strong&gt;Inspection Authorization&lt;/strong&gt; would approve the aircraft for return to service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A little extra reading - &lt;a href=&quot;https://aviation.stackexchange.com/questions/22362/who-can-perform-different-maintenance-checks&quot;&gt;Who can perform different maintenance checks?&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-28T11:45:53.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22463" PostTypeId="5" CreationDate="2015-10-28T13:50:46.167" Score="0" Body="&lt;p&gt;Preparing for a written test required to get a pilot rating&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="62" LastEditDate="2015-10-28T15:05:05.900" LastActivityDate="2015-10-28T15:05:05.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22464" PostTypeId="4" CreationDate="2015-10-28T13:50:46.167" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2015-10-28T13:50:46.167" LastActivityDate="2015-10-28T13:50:46.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22465" PostTypeId="2" ParentId="22456" CreationDate="2015-10-28T14:45:20.430" Score="2" Body="&lt;p&gt;Many of the 'variables' you mention, are in fact &lt;strong&gt;fixed&lt;/strong&gt;, and in large determined by &lt;strong&gt;dispatch&lt;/strong&gt; (the smart folks at the company). For commercial flight, the &lt;strong&gt;flight plan&lt;/strong&gt; will be filed in advance (generally by the company dispatch), and will contain all the waypoints en route, including expected flight levels. Dispatch makes the calculation for the most efficient flight in close collaboration with ATC authorities, for example by reserving slots on certain airways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deviations from the flight plan are not common - you won't hear ATC tell an airplane mid-flight to suddenly take the long way round - instead, any route alterations are communicated to the pilots when they are still on the ground, and if necessary, extra fuel is taken on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This flight plan is then given to the pilots, and programmed into the FMC. The FMC is a very sophisticated piece of software, and can in fact calculate the required fuel for this leg all by itself - you can even program it to calculate the best trade-off between efficiency and speed (see &lt;a href=&quot;https://youtu.be/9NFq2eZSDJE&quot; rel=&quot;nofollow&quot;&gt;this KLM video&lt;/a&gt; at 1:40). I'm not entirely sure about the details, but you can probably program the SID and STAR of the departure and destination airports respectively as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of this, extra fuel is taken on board for things like &lt;strong&gt;taxi&lt;/strong&gt;, expected &lt;strong&gt;holding&lt;/strong&gt; patterns (your dispatcher will know how busy you can expect it to be at your destination airport; e.g., Heathrow is generally very busy and you might want to take some extra fuel on board), and enough fuel to at least be able to perform a few go-arounds or a diversion if circumstances call for it. In the end, the pilot is responsible for taking enough fuel on board, but will rely on the FMC and dispatch to make an educated guess.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2015-10-28T14:45:20.430" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22466" PostTypeId="1" AcceptedAnswerId="22467" CreationDate="2015-10-28T15:53:22.177" Score="8" ViewCount="5486" Body="&lt;p&gt;Some airports (mostly busy Class B airports from what I gather) have a &lt;a href=&quot;https://en.wikipedia.org/wiki/Landing_fee&quot; rel=&quot;noreferrer&quot;&gt;landing fee&lt;/a&gt;. For example, in the Airport Facility Directory &lt;a href=&quot;http://aeronav.faa.gov/afd/15oct2015/sw_195_15OCT2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;for San Francisco&lt;/a&gt;, there is a section under &quot;AIRPORT REMARKS&quot; that says &quot;Ldg fee.&quot; In a Summary of Airport Charges &lt;a href=&quot;http://media.flysfo.com.s3.amazonaws.com/assets/investor/summary-airport-charges_fy15-16.pdf&quot; rel=&quot;noreferrer&quot;&gt;for San Francisco airport&lt;/a&gt;, this fee is listed as at least $190 for Fixed-wing GA aircraft! There is no mention in this document about how the fee is collected, however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this fee collected?&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2015-10-28T16:03:50.433" LastActivityDate="2019-09-27T16:47:07.817" Title="How are Landing Fees Collected?" Tags="&lt;airport&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22467" PostTypeId="2" ParentId="22466" CreationDate="2015-10-28T15:54:54.160" Score="4" Body="&lt;p&gt;This depends on the airport but at &lt;a href=&quot;http://www.airnav.com/airport/kpne&quot; rel=&quot;nofollow noreferrer&quot;&gt;KPNE&lt;/a&gt; where I used to fly there was a $5 landing fee (paid to the city of Philadelphia) that was collected at the FBO (where I rented the plane from) when I paid for the rental. I think if you do not pass through an FBO they will hunt the tail number down and send a bill to the party that has the aircraft registered. Its tough to fly into an airport and not pass through the FBO (unless you are just doing touch and goes). I would assume that for commercial traffic the airline/owning body pays and may even be billed by the airport monthly but I don't know the specifics I only know what I have seen for GA traffic.&lt;/p&gt;&#xA;&lt;p&gt;If you are curious you can check out the Philadelphia Airport (KPHL and KPNE) &lt;a href=&quot;https://www.phl.org/drupalbin/media/PHLRRAppH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;legislation here&lt;/a&gt; which outlines the various fess and collection mechanisms the city imparts. Keep in mind these are city owned airports, see section V for details on collection but in short,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Section V Part d&lt;/p&gt;&#xA;&lt;p&gt;Non-tenant Air Carriers and Operators not providing adequate surety or security in form and amount satisfactory to the Department of Commerce, to ensure payment of fees and charges, shall be required to pay all incurred fees and charges prior to aircraft departure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For the point of contrast lets take a small privately owned airport here in the US, &lt;a href=&quot;http://www.solbergairport.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Solberg Airport&lt;/a&gt; in NJ has &lt;a href=&quot;http://www.solbergairport.com/current-rates/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&amp;quot;ramp fees&amp;quot;&lt;/a&gt; for parking and the such, but like most small airports like this, these fees are waved with the purchase of fuel (usually at least some minimum amount). There would be no way to avoid paying (well Im sure there is) since usually the only way off the tarmac is through the FBO.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-09-27T16:47:07.817" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="22469" PostTypeId="2" ParentId="3569" CreationDate="2015-10-28T17:33:15.777" Score="0" Body="&lt;p&gt;An amphibian may be flown as a land only aircraft without the sea endorsement.  A pilot must not have the intention to land or take-off from water.&lt;/p&gt;&#xA;" OwnerUserId="12030" LastActivityDate="2015-10-28T17:33:15.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22470" PostTypeId="2" ParentId="22443" CreationDate="2015-10-28T17:37:41.950" Score="5" Body="&lt;p&gt;The FAA &quot;Class D&quot; maintenance/inspection of commercial airliners, which must occur every 6 years, is extremely thorough:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The cabin trim is completely removed to inspect the airliner's skin and superstructure from the inside. Seats, safety equipment and control system linkages are also inspected in detail with each individual cable or wire tested.&lt;/li&gt;&#xA;&lt;li&gt;The plane's exterior paint is removed to inspect the exterior skin, including rivets and seams.&lt;/li&gt;&#xA;&lt;li&gt;All critical moving parts on the exterior of the plane (engines, gear, ailerons, flaps, spoilers, rudder, elevators, shock booms, etc), are removed from the plane, disassembled and visually inspected for wear or damage, then re-assembled and tested.&lt;/li&gt;&#xA;&lt;li&gt;All pressurized lines (hydraulic, water, fuel) are removed from the plane and each part individually visually inspected before being re-assembled and pressure-tested in the plane.&lt;/li&gt;&#xA;&lt;li&gt;The cockpit is stripped, all moving parts in the control column and throttle assemblies visually inspected, and all flight instruments visually inspected and tested.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are many more maintenance/inspection tasks than I list, I'm just going through the major ones. The plane is more or less stripped to its bare metal frame, every component visually inspected and tested, then the aircraft is reassembled with individual systems tested again on the airframe. The process can take up to two months for each aircraft, and can cost between 5 and 7 million US dollars. Most major airlines have either their own in-house maintenance crews or the manufacturer perform this maintenance, with a team of FAA-employed inspectors overseeing and signing off on all the work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airliners receive 3 Class D inspections in their lifetime; at the fourth, occurring around 24 years of airframe age, the cost of a Class D is typically not considered worth it given the aircraft's remaining value, and the aircraft is usually retired and either sold to smaller non-US airlines operating in jurisdictions with less stringent standards, mothballed and stored for potential replacement parts value to the rest of the fleet, or sold for scrap. Some airframes in service with some airlines have been kept through four Class Ds in order for the airline to have sufficient time to procure replacements; American's remaining MD-80s are largely newer airframes acquired in the TWA merger, but there are a few of American's own deliveries left in the fleet which are past 24 years and are still around mainly to allow American sufficient time to work through the bankruptcy, United merger and procurement of replacements (Boeing's 737 production lines are going full-tilt and American is not the highest-priority customer, so American had to split its order in this class between the 737 and Airbus's A319 and A321).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the level of detail and deconstruction required, including complete cabin trim and paint removal, airlines often use this maintenance interval to perform any desired upgrades or tweaks to their fleet configuration. Common upgrades in recent years have included:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;adding winglets for vortex reduction (reducing drag and allowing closer spacing at busy airports),&lt;/li&gt;&#xA;&lt;li&gt;upgrading avionics and even control systems (some older airframes can be upgraded from direct cable-driven hydraulics to electro-hydraulic controls allowing partial automation of flight with EFDs), &lt;/li&gt;&#xA;&lt;li&gt;upgrades to cabin trim including re-spacing of passenger seats (more or less legroom or &quot;slant&quot;, balancing between class seating), &lt;/li&gt;&#xA;&lt;li&gt;replacing galley equipment and other secondary systems that may be a different standard from the rest of the fleet, &lt;/li&gt;&#xA;&lt;li&gt;adding new passenger conveniences (such as satellite-based Wi-Fi, headrest IFE, etc) and &lt;/li&gt;&#xA;&lt;li&gt;new exterior paint schemes for corporate rebranding (such as American's ongoing rebadging from their decades-old AA silver to the new American white, and Southwest's recent move to the &quot;Heart&quot; scheme from its older &quot;Canyon Blue&quot; and the original red/gold before that). &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aircraft acquired in airline mergers are often the highest priority as the airline seeks to rebadge and standardize the acquired fleet to operate alongside its existing planes (and ensure no corners were cut by a struggling airline that would create liabilities going forward).&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2015-10-28T18:00:47.290" LastActivityDate="2015-10-28T18:00:47.290" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22471" PostTypeId="2" ParentId="21992" CreationDate="2015-10-28T18:35:14.633" Score="1" Body="&lt;p&gt;One possibility is to contact the FAA &lt;a href=&quot;https://nfdc.faa.gov/xwiki/bin/view/NFDC/56DaySub-2015-06-25&quot; rel=&quot;nofollow noreferrer&quot;&gt;National Flight Data Center (NFDC)&lt;/a&gt;. They provide information as part of the US Aeronautical Information Services (AIS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NFDC Support Desk email is available on &lt;a href=&quot;https://nfdc.faa.gov/portal/login.do&quot; rel=&quot;nofollow noreferrer&quot;&gt;this login page&lt;/a&gt;, below the login data boxes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9681/where-to-find-a-waypoints-fixed-points-navaids-airports-database&quot;&gt;Where to find a waypoints/fixed points, navaids, airports database&lt;/a&gt; for other aeronautical data sets in case you need them too.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-28T18:35:14.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22472" PostTypeId="1" AcceptedAnswerId="22476" CreationDate="2015-10-28T18:50:59.777" Score="41" ViewCount="4019" Body="&lt;p&gt;A few hours ago, a rather large (243 feet long) helium blimp owned by NORAD broke loose of its moorings in the Eastern United States and floated away. The news is currently reporting that it's being &quot;escorted&quot; by a pair of F-16's as it floats along at 15,000 feet, and is currently somewhere over Pennsylvania. (Next state over from where it started, at the Aberdeen Proving Grounds in Maryland.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given this situation, what are the military's options for recovering this blimp? Do they have to wait for it to crash land somewhere eventually (when it runs out of wind, I suppose?) Or is there some other option for them to &quot;catch&quot; this blimp given its size and the fact it's pretty much under nobody's control?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an article about it: &quot;&lt;a href=&quot;http://www.baltimoresun.com/news/maryland/harford/aberdeen-havre-de-grace/bs-md-jlens-blimp-loose-20151028-story.html&quot; rel=&quot;noreferrer&quot;&gt;JLENS blimp has come free of its tether at APG, now floating over Pennsylvania; fighter jets monitoring.&lt;/a&gt;&quot; The &lt;em&gt;Baltimore Sun&lt;/em&gt;. 28 October 2015, 14:34 ET.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;br /&gt;&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; In case anyone is curious, the blimp landed in Pennsylvania a few hours after I posted this question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Miklaszewski, J. &quot;&lt;a href=&quot;http://www.nbcnews.com/news/us-news/national-guard-shoot-crashed-blimp-help-it-deflate-n453981&quot; rel=&quot;noreferrer&quot;&gt;National Guard to Shoot at Crashed Blimp to Help It Deflate.&lt;/a&gt;&quot; NBCNews.com. 29 October 2015, 14:32 ET.&lt;/p&gt;&#xA;" OwnerUserId="373" LastEditorUserId="3386" LastEditDate="2018-04-21T14:31:04.920" LastActivityDate="2018-04-22T00:53:08.560" Title="How do you catch a runaway blimp?" Tags="&lt;lighter-than-air&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22473" PostTypeId="2" ParentId="22447" CreationDate="2015-10-28T19:03:21.410" Score="2" Body="&lt;p&gt;&lt;strong&gt;Example of two ~static thrust tests&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1)&lt;/strong&gt; Engine: C-85-12 Continental (&lt;strong&gt;85hp&lt;/strong&gt;, redline 2575rpm)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller: McCauley 71×46 Met-L, aluminum (This is a climb prop for a 120)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind: 4-9mph headwind&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Performance -- Thrust: &lt;strong&gt;340 pounds&lt;/strong&gt;, RPM: 2350&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller efficiency: ~ &lt;strong&gt;37.5%&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2)&lt;/strong&gt; Engine: Continental O-200, &lt;strong&gt;100hp&lt;/strong&gt;, 2750rpm redline&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller: McCauley Clip Tip 68″ diameter, aluminum, standard pitch&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind: 5-7mph headwind&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Performance -- Thrust: &lt;strong&gt;335 pounds&lt;/strong&gt;, RPM: 2332&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propeller efficiency: ~ &lt;strong&gt;32.5%&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;see: &lt;a href=&quot;http://flycorvair.net/2013/12/23/thrust-testing-85-and-100-hp-engines/&quot; rel=&quot;nofollow&quot;&gt;Thrust testing 85 and 100 hp engines&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The efficiency was calculated using the formula: $\eta_{prop} = \sqrt{\frac{T^3}{(P^2 \cdot \pi \cdot \eta_{gears} \cdot \frac{D^2}{2} \cdot \rho )}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conclusion:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the formula for $\eta_{prop}$ is reliable it seems that a modern propeller has a rather poor efficiency during a static thrust measurement. Gustave Whitehead might have optimized his aerial screws for supplying maximum static thrust possible but even in this case he could not have obtained an efficiency above 90%.  &lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-28T19:03:21.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22474" PostTypeId="1" AcceptedAnswerId="22477" CreationDate="2015-10-28T19:16:00.770" Score="4" ViewCount="414" Body="&lt;p&gt;From my research I've found that (correct me if i am wrong):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Structure inspection (in B,C and D Checks) including (visual, thermography, ultrasonic inspections) looking for structure damage of different type of composit materials (like cracks, dis-bonding, delamination, water ingestion, holes, dents ... etc) in commercial airliners specially wide body aircraft takes alot of time, labor and cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why isn't it done by robots which should be more time efficient, accurate and reliable? in a way that robots can do simple but mandatory inspection tasks allowing operators to focus on more skilled tasks (like engine work) reducing the overall plane down time !&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any robotic inspection systems exists that I didn't hear about? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How beneficial to airlines would it be to have a robotic system that would &lt;strong&gt;assist&lt;/strong&gt; operators in the inspection process (in terms of time and cost) ?     &lt;/p&gt;&#xA;" OwnerUserId="12014" LastEditorUserId="12014" LastEditDate="2015-10-29T05:46:07.800" LastActivityDate="2015-10-29T05:46:07.800" Title="Why isn't aircraft structure inspection done by robots? Is there any known active research on the subject?" Tags="&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;&lt;cost&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22475" PostTypeId="2" ParentId="22472" CreationDate="2015-10-28T19:29:29.720" Score="10" Body="&lt;p&gt;That would be an odd sight for passengers on nearby airliners, to be sure...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The options for dealing with a runaway like this depend on the airship's cost and capabilities. This particular blimp appears to be closer to a balloon; no propulsion, no on-board piloting capability, basically its job is to face the prevailing winds coming on from the Atlantic allowing the radar in its gondola to scan for incoming cruise missiles (and track ships at sea and cars on the roads in DC, apparently; at least it's capable of doing so).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it were an ordinary camera balloon, like the ones forming a part of the &quot;virtual fence&quot; along the U.S.-Mexico border, the F-16s would likely have already been given the order to take it out with a burst from the 20mm. The problem with this blimp is that it's one of two prototypes resulting from a $17 billion R&amp;amp;D project; they're not just going to shoot it down like that unless it's the very last option to prevent the blimp leaving U.S.-controlled airspace on its way to Canada (and, eventually, Russia).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best option would probably be to approach it with something a little slower than an F-16, either a manned blimp or a slow, long-range prop job, and get a hold of the blimp with a tow tether. The blimp could then be towed back to Aberdeen (or any nearby airstrip). The technical issues would be daunting, though:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Getting hold of the balloon from another aircraft at 15,000 feet without a collision or other damage to either aircraft is harder than it sounds; you can't just calf-rope it.&lt;/li&gt;&#xA;&lt;li&gt;The balloon isn't designed to be towed at any appreciable speed; you'd probably have to use another blimp, something able to make headway against the wind but at a slow enough airspeed that the towed blimp doesn't come apart. The U.S. military doesn't operate many manned blimps in the 21st century.&lt;/li&gt;&#xA;&lt;li&gt;The balloon doesn't appear to have been designed with any altitude control in mind; this means whatever other aircraft tows it back to Maryland is going to have to pull it down from 15,000 feet against the force of lift from the blimp's gas bag. This may require the towing aircraft to more or less hang from the tow tether, which isn't guaranteed to be secure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Honestly, the safest solution sounds like taking up a skydiving aircraft with a sniper, everyone on oxygen, and having the sniper shoot the balloon to cause a slow leak of its helium. The remaining problem is that the balloon is too high to get back on the ground before its entire helium supply is gone, so if the blimp doesn't have a ballistic parachute, you're going to lose a very expensive radar gondola.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2015-10-28T19:29:29.720" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="22476" PostTypeId="2" ParentId="22472" CreationDate="2015-10-28T20:09:22.787" Score="22" Body="&lt;p&gt;Historically, a runaway airship cannot be caught or entered. Eventually it will come down - they all did so far. Only in one case did a Zeppelin fragment of a ship which broke up in a storm make a soft landing so the crew aboard could survive. In all other cases both ship and crew perished or were never seen again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the Zeppelins had vertical shafts which allowed the crew to climb to the top of the hull, a blimp can only be entered below the hull. Trying to lower someone James-Bond-style from above will fail, because the big hull will shield the entry points of the gondola very effectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8EemE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8EemE.jpg&quot; alt=&quot;Defensive gunner position on a Zeppelin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Defensive gunner position on a Zeppelin. Note the square hatch at the bottom which leads down to the bottom of the ship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, shooting it down will be an exercise in futility. All it will do is to increase the rate of helium loss, so the flight will be some hours shorter. Helium is inert and will not burn, and those small holes will be tiny relative to the big surface of the hull.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 15,000 ft it will be hard to try to catch one of the lines most likely hanging from the blimp with a helicopter. Remember that the blimp floats, so the helicopter has to hover at this altitude. Very few are able to do so. Towing will only be possible with another blimp or a helicopter; an airplane will not be able to fly fast enough with a blimp in tow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next trick depends on the color of the hull: If it is dark, covering it with something highly reflective will cool it and reduce the blimp's buoyancy. I have, however, no idea how to get a big blanket on that thing. The same will happen when night falls, but first the air will cool and the blimp, which will cool down more slowly, will go up. Later in the night and early in the morning it will sink again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wet parts of rain clouds will mostly be below 15,000 ft (water content is proportional to air density, after all), so a shower which drenches the hull and makes it heavier is highly unlikely. There is no obvious way how this thing will come down fast. Except, that is, it climbs further and the hull bursts. This will change the dynamics of this escape in a dramatic way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chase planes will help ATC to route traffic around the blimp, and all that can be done is to watch it. With luck the landing will be soft enough that it is not a complete write-off.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-28T22:27:23.960" LastActivityDate="2015-10-28T22:27:23.960" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="22477" PostTypeId="2" ParentId="22474" CreationDate="2015-10-28T21:00:24.987" Score="10" Body="&lt;p&gt;The robot, or better the software analyzing the sensor output, needs to be programmed for every eventuality. After all, wear and tear does not leave standard traces, and a human is still better in spotting when something does not look quite right. This does not concern the obvious cases, but those where experience and intuition make the difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, aircraft structures are made with human inspectors in mind. A robotic system would need to be able to access all points at least as well as a human can. This puts some heavy restrictions on the robot's physique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually, a robotic system will surpass most humans, but only after thousands of man-hours of training. Maybe someone is developing just such a system right now, but I am unaware of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One point remains, however: Who will be liable if the robotic system makes a mistake? The manufacturer will need to buy insurance to cover those corner cases where the robot fails, and this will come on top of the hefty expense for developing and training such a system. I expect that the military (e.g. &lt;a href=&quot;http://www.darpa.mil&quot;&gt;DARPA&lt;/a&gt;) will be the first to make the plunge, and only when the robot has a positive track record will civilian operators start to consider using it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EasyJet drones are just helping to get a camera on top of the aircraft; the eventual monitoring of the feed will still be performed by humans. They are a high-tech version of a periscope, if you want.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-28T21:19:53.180" LastActivityDate="2015-10-28T21:19:53.180" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22478" PostTypeId="1" AcceptedAnswerId="22504" CreationDate="2015-10-28T21:15:41.143" Score="7" ViewCount="1091" Body="&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-SUPP_TECH-SEQ01.pdf&quot;&gt;This pdf&lt;/a&gt; from Airbus has a chart from ICAO showing the amount of correction to be applied to altimeter readings for temperatures below 0°C. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do aircraft with flight data computers automatically correct for this?&lt;/li&gt;&#xA;&lt;li&gt;In the US, does ATC account for this correction when assigning vectors? &lt;/li&gt;&#xA;&lt;li&gt;How does a pilot know if they are or not?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="69" LastEditDate="2015-10-29T18:04:12.130" LastActivityDate="2015-11-05T02:52:03.707" Title="How is non-standard OAT accounted for?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;altitude&gt;&lt;altimeter&gt;&lt;density-altitude&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22479" PostTypeId="2" ParentId="22447" CreationDate="2015-10-28T21:44:06.233" Score="4" Body="&lt;p&gt;As you present it, you are right and Whitehead's numbers are impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I doubt that he could measure engine power with enough precision, and who knows what definition for horsepower he used. Power measurement &lt;a href=&quot;https://aviation.stackexchange.com/questions/22402/how-is-horsepower-measured-for-aviation-piston-engines&quot;&gt;needs some heavy machinery&lt;/a&gt;, and Whitehead most likely did not own a suitable dynamometer. It would be interesting to know the fuel consumption of this engine - that could help to check his numbers better.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-10-28T21:44:06.233" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22481" PostTypeId="1" CreationDate="2015-10-28T22:45:34.787" Score="7" ViewCount="652" Body="&lt;p&gt;Can you identify this plane?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ClNo0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ClNo0.jpg&quot; alt=&quot;Unknown airplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unknown airplane&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have just found the photo on a CD together with many other planes and helicopters. I have no clue regarding the place where the picture was taken, the time and the type of the plane.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-10-28T23:45:34.330" Title="Can you identify this plane?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22482" PostTypeId="2" ParentId="22481" CreationDate="2015-10-28T22:58:35.920" Score="8" Body="&lt;p&gt;@Roddy is correct. It is an Romanian &lt;a href=&quot;https://en.wikipedia.org/wiki/IAR_80&quot; rel=&quot;noreferrer&quot;&gt;IAR-80&lt;/a&gt; all right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OJfLX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OJfLX.jpg&quot; alt=&quot;IAR-80&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:IAR80.jpg#/media/File:IAR80.jpg&quot; rel=&quot;noreferrer&quot;&gt;IAR80&lt;/a&gt;&quot; by user:Planck -  &lt;a href=&quot;//commons.wikimedia.org/wiki/Commons:Licensing&quot; rel=&quot;noreferrer&quot; title=&quot;Commons:Licensing&quot;&gt;licensing policy&lt;/a&gt;.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IAR-80 was produced by IAR (Intreprinderea Aeronautică Română), an airplane manufacturer that was the property of the Romanian State until the end of the WWII. The aircraft first flew in 1938 and was in service till 1952.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The model appears to be the IAR 81. The same image can be found &lt;a href=&quot;http://avia-museum.narod.ru/romania/iar-80.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. It was probably taken in the eastern front.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-28T23:45:34.330" LastActivityDate="2015-10-28T23:45:34.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22484" PostTypeId="2" ParentId="22472" CreationDate="2015-10-28T23:28:01.150" Score="1" Body="&lt;p&gt;A blimp does not have an internal structural framework or a keel and relies on the pressure of the lifting gas (usually helium) for lift. It is basically a huge helium balloon and a way to bring it down is to release the gas by puncturing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no (safe) way to catch a blimp as the only entry point is below the gas bag. The best option is to shoot it down using incendiary bullets. During WWI, firebombs were used against Zeppelins (though these were filled with hydrogen, not helium).    &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="13124" LastEditDate="2018-04-22T00:53:08.560" LastActivityDate="2018-04-22T00:53:08.560" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22488" PostTypeId="1" CreationDate="2015-10-29T17:09:55.987" Score="0" ViewCount="4466" Body="&lt;p&gt;What services do each provide and on what frequencies?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-10-30T00:23:44.717" Title="What is the difference between EFAS and FSS?" Tags="&lt;weather&gt;&lt;fss&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ClosedDate="2015-10-30T03:08:41.683" ContentLicense="CC BY-SA 3.0" />
  <row Id="22489" PostTypeId="1" CreationDate="2015-10-29T17:20:12.763" Score="8" ViewCount="2258" Body="&lt;p&gt;In the next picture can be seen within the housing, near the inlet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dy6ZL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dy6ZL.jpg&quot; alt=&quot;Front view of turbofan engine&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DNCT7.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DNCT7.png&quot; alt=&quot;Closeup of inlet section&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/UFxXv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UFxXv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="3386" LastEditDate="2017-06-20T17:24:46.273" LastActivityDate="2019-03-05T00:38:57.673" Title="What are these holes in the engine inlet?" Tags="&lt;jet-engine&gt;&lt;feature-identification&gt;" AnswerCount="3" CommentCount="14" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22490" PostTypeId="2" ParentId="15772" CreationDate="2015-10-29T17:51:08.753" Score="6" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Center_of_gravity_of_an_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;Calculation section of “Center of gravity of an aircraft”&lt;/a&gt; on Wikipedia gives an overview of the steps.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Determine the weights and arms of all mass within the aircraft.&lt;/li&gt;&#xA;  &lt;li&gt;Multiply weights by arms for all mass to calculate moments.&lt;/li&gt;&#xA;  &lt;li&gt;Add the moments of all mass together.&lt;/li&gt;&#xA;  &lt;li&gt;Divide the total moment by the total weight of the aircraft to give an overall arm.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Basic Empty Weight (BEW) of the aircraft will come from the Weight &amp;amp; Balance information that is unique to each aircraft. The computed arm for the BEW may have some rounding error, so treat it as informational. Use the precise figures for Weight and Moment from your aircraft’s W&amp;amp;B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The arms, distances from some reference datum, will also come from your aircraft’s W&amp;amp;B info: fuel, front seats, rear seats, and baggage areas on a Cessna 172. Copy those into your table as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avgas (100LL) weighs 6 pounds per gallon, so the weight is 6 times the number of gallons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to work top-to-bottom and left to right. For the grand finale, divide the sum of the Moment column by the sum of the Weight column to get the overall center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The example below is from my PP-ASEL checkride taken in a Cessna 172. The items in &lt;strong&gt;boldface&lt;/strong&gt; are computed values. The digits after the decimal are there for typographical purposes and do not necessarily indicate significant figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{array}{c|r|r|r|}&#xA;                     &amp;amp; \textit{Weight} &amp;amp; \textit{Arm} &amp;amp; \textit{Moment} \\ \hline&#xA;\text{Airplane}      &amp;amp; 1{,}665.6     &amp;amp; 39.2       &amp;amp; 65{,}928.93      \\&#xA;                     &amp;amp;               &amp;amp;            &amp;amp;                  \\&#xA;\text{Fuel (50 gal)} &amp;amp; \bf{300.0}    &amp;amp; 48.0       &amp;amp; \bf{14{,}400.00} \\&#xA;                     &amp;amp;               &amp;amp;            &amp;amp;                  \\&#xA;\text{Bacon}         &amp;amp; 180.0         &amp;amp; 37.0       &amp;amp; \bf{6{,}660.00}  \\&#xA;\text{Shelton}       &amp;amp; 172.0         &amp;amp; 37.0       &amp;amp; \bf{6{,}364.00}  \\&#xA;                     &amp;amp;               &amp;amp;            &amp;amp;                  \\ \text{Duffel}        &amp;amp; 10.0          &amp;amp; 73.0       &amp;amp; \bf{730.00}      \\&#xA;\text{Shelton bag}   &amp;amp; 10.0          &amp;amp; 73.0       &amp;amp; \bf{730.00}      \\&#xA;                     &amp;amp;               &amp;amp;            &amp;amp;                  \\ &#xA;\text{Backpack}      &amp;amp; 15.0          &amp;amp; 93.3       &amp;amp; \bf{1{,}399.50}  \\ \hline&#xA;                     &amp;amp; \bf{2{,}352.6}&amp;amp; \bf{40.9}  &amp;amp; \bf{96{,}212.43}&#xA;\end{array}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this particular case—given for information only—the center of gravity (40.9 ≈ 96,212.43 / 2,352.6) at the total weight is within limits for the Normal category as given in the aircraft’s Pilot Operating Handbook (POH). Your case may vary. The Pilot-in-Command is responsible for computing Weight &amp;amp; Balance for each flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a point of interest, my DPE was Clyde Shelton who recently &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/September/09/Pilot-examiner-Shelton-awards-ten-thousandth-certificate&quot; rel=&quot;nofollow noreferrer&quot;&gt;flew his &lt;em&gt;ten thousandth&lt;/em&gt; checkride&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2018-03-17T21:56:43.993" LastActivityDate="2018-03-17T21:56:43.993" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22491" PostTypeId="1" CreationDate="2015-10-29T18:49:43.290" Score="19" ViewCount="7515" Body="&lt;p&gt;Can tilt-rotors like the V-22 execute an autorotation landing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, are the conditions under which that would be possible (and survivable) different from a helicopter?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastActivityDate="2016-01-16T17:24:52.770" Title="Can the V-22 autorotate?" Tags="&lt;auto-rotation&gt;&lt;vtol&gt;&lt;v-22&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22492" PostTypeId="1" AcceptedAnswerId="22497" CreationDate="2015-10-29T18:59:55.123" Score="9" ViewCount="1341" Body="&lt;p&gt;Following up on &lt;a href=&quot;https://aviation.stackexchange.com/q/22427/11671&quot;&gt;this question&lt;/a&gt;: If a helicopter lacks power to climb vertically (i.e., with no translational movement) out of ground effect, is it ever considered safe to fly?  If so, under what conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is the hover capability of a helicopter generally considered to be independent of its safe flight envelope?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-11-01T00:25:54.633" Title="Should helicopters fly when they the lack power for vertical climb out of ground effect?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;hover&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22493" PostTypeId="2" ParentId="22491" CreationDate="2015-10-29T19:03:31.943" Score="10" Body="&lt;p&gt;This seems to be &lt;a href=&quot;http://www.g2mil.com/V-22safety.htm&quot;&gt;a hot topic&lt;/a&gt; - in principle, the V-22 should be able to fly and land in autorotation, but tests so far did not demonstrate this. The &lt;a href=&quot;http://pogoblog.typepad.com/pogo/2007/10/v-22-defender-s.html&quot;&gt;manufacturer's position&lt;/a&gt; is that autorotation was never part of the specification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it comes down to is the inertia of the rotating parts relative to the aircraft's mass. The requirement to fold the rotors put a limit on their diameter and consequently their inertia while increasing their disc loading. The inertia is too low to reduce the rate of descent enough to enable a safe and soft landing. Quote from &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey#Controversy&quot;&gt;Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;While technically capable of autorotation if both engines fail in&#xA;  helicopter mode, a safe landing is difficult;[73] in 2005, a director&#xA;  of the Pentagon's testing office stated that in a loss of power while&#xA;  hovering below 1,600 feet (490 m), emergency landings &quot;...are not&#xA;  likely to be survivable.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is specific to the V-22 - other tiltrotors might well be able to land in autorotation if their rotor inertia and speed is high enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For all practical purposes, the V-22 can glide down in autorotation, but will not be able to perform a soft landing at the end of this glide.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-29T20:19:10.993" LastActivityDate="2015-10-29T20:19:10.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22494" PostTypeId="2" ParentId="22491" CreationDate="2015-10-29T19:06:05.857" Score="21" Body="&lt;p&gt;The V-22 rotor disks are much lighter than a helicopter's. There's little energy available to use to cushion a landing, so although autorotation is theoretically possible, there's little point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.boeing.com/ospreynews/2011/issue_01/final_8jun2010_179638.pdf&quot;&gt;Boeing V-22 handbook&lt;/a&gt; has this to say (see page 26):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The V-22 is a tiltrotor and does not rely on autorotation for  a&#xA;  survivable power-out landing. The wide separation of the  engines and&#xA;  the ability to drive both rotors with one engine  make a power-out&#xA;  landing extremely unlikely. However, if  required, the V-22 can glide&#xA;  for a predictable run-on landing in  airplane mode, much like a&#xA;  turboprop&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've seen glide ratios of 2:1 and 4.5:1 quoted on the Internet, so it'll come down quite hard and destroy the rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the design mitigates against this in various ways, or so the manufacturer claims. In the survivability section of the same handbook they say&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;V-22 crashworthiness is a function of design. Heavy components,  such&#xA;  as the engines and transmissions, are located away from  the cabin and&#xA;  cockpit area. The proprotors are designed to fray or  “broomstraw”&#xA;  rather than splinter on impact with the ground. The  energy-absorbing&#xA;  landing gear system is designed to attenuate  most of the energy for&#xA;  hard landings up to 24 fps. The wing is  constructed to fail outboard&#xA;  of the wing/fuselage attachment in a  manner that absorbs kinetic&#xA;  energy and ensures the cabin area will  not be crushed, thereby&#xA;  protecting the occupants. An anti-plow  bulkhead prevents the nose&#xA;  from digging in on impact, and the  fuselage provides a reinforced&#xA;  shell that is designed to maintain 85%  of its volume during a crash.&#xA;  Aircrew and embarked troops receive  additional protection from&#xA;  crashworthy seats that stroke vertically to  absorb energy.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user11933" LastEditorDisplayName="user11933" LastEditDate="2015-10-30T23:40:05.417" LastActivityDate="2015-10-30T23:40:05.417" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22495" PostTypeId="1" AcceptedAnswerId="22499" CreationDate="2015-10-29T19:43:11.433" Score="11" ViewCount="614" Body="&lt;p&gt;My understanding is that during power-off autorotation the main rotor is still coupled to the tail rotor, and the flight controls execute the same functions as during power-on flight.  Two questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Do any (heavy) helicopters have power-assisted controls?  If so are those difficult to handle in the event of total power failure?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How is the input during autorotation different from the input for the same attitude under power?  E.g., during a given glide and flare to land are the rotor blade angles of attack and swashplate orientation identical to when the a rotors are powered?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11671" LastActivityDate="2018-02-04T04:28:15.247" Title="Are control inputs different during autorotation?" Tags="&lt;flight-controls&gt;&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22496" PostTypeId="2" ParentId="22478" CreationDate="2015-10-29T19:44:26.760" Score="1" Body="&lt;p&gt;From ICAO (sorry can't remember word-to-word, but close): Temperature correction must be made to all minimum altitudes at and below MSA when station temperature is at or below 0 degrees celsius.&lt;br&gt;&#xA;1. Yes, FMS can make the correction, but at least in some versions you have to enable it for each flight. Also a specific approval is needed to use the FMS correction.&lt;br&gt;&#xA;2. Followong applies to EU, not sure about US: Under radar control ATC &lt;strong&gt;should&lt;/strong&gt; make the correction. Without radar they don't.&lt;br&gt;&#xA;3. If the controller makes the temperature correction, he/she &lt;strong&gt;should&lt;/strong&gt; notify you by adding &quot;temperature correction made by atc&quot; or &quot;temperature corrected&quot; to the clearance. Ie &quot;descend to 3000ft, temperature corrected&quot;&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-10-29T19:44:26.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22497" PostTypeId="2" ParentId="22492" CreationDate="2015-10-29T20:19:33.197" Score="8" Body="&lt;p&gt;Up to a certain speed, which will be in the POH, the greatest power requirement is when hovering out of ground effect.  Next is hovering in ground effect and power required in forward flight is the lowest, and &lt;em&gt;decreases&lt;/em&gt; up until a point where the increase in parasitic drag starts to increase the power required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See a typical power required curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8WOOs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8WOOs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://blog.aopa.org/helicopter/wp-content/uploads/2015/03/downwind-takeoff.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;From the AOPA blog&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it is possible to not have enough power margin to be able to hover OGE but enough to hover IGE.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To perform a normal take-off (ignoring a lot of side effects such as need for pedal), come to a normal hover height, about 2-3 feet, then push the cyclic forward.  Increase collective smoothly to maintain altitude and allow the aicraft to accelerate which it will, since increasing collective increases power and the rotor thrust now has a forward horizontal component. As significant translational lift kicks in at about 10 kts, a reduction in collective is required to avoid climbing early.  You don't want to be climbing with high pitch, and therefore high drag, if the engine quits.  When reaching about 45 kts or so, pull back on the cyclic to adopt a climbing attitude.  The aircraft will settle at about 65 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To perform a &quot;creeping&quot; take-off, increase collective to become light on the skids.  Gentle forward pressure on the cyclic will start a slide on the ground. As translational lift kicks in, apply a little back pressure to lift gently to climb to about 1-2 feet to remain in maximum ground effect and continue to accelerate.  Wait until 45 kts is reached, and off you go.  During this manouver, the collective is left where it is until established in the climb, aside from small adjustments needed to keep the altitude constant during the creep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure if it is a certification requirement, but every helicopter I've flown is capable of safely flying when there is not enough power margin to hover OGE, and most helicopters I have flown are on the weak side (R22, B206, B206L, S300, Enstrom 280) so I guess all helicopters can do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://easa.europa.eu/document-library/type-certificates&quot; rel=&quot;nofollow noreferrer&quot;&gt;I checked a few types certs&lt;/a&gt; and I can see nothing about creeping take-offs. I am reasonably sure that the only limits that apply are for RPM, MAP, torque, N1, N2, temperatures etc. As long as you don't exceed those and are in accordance with the POH, then it doesn't matter how you get airborne. As you can see from the power required curve, the power required for forward flight is a great deal lower than for hover. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've copied in your comment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I understand that vertical climbing is not hovering, but neither is it&#xA;  &quot;flying&quot; in the same sense that translational flight adds lift.&#xA;  Positive vertical climb out of ground effect with no translation is, I&#xA;  deduce, the hardest thing a helicopter can do. The maximum rate of&#xA;  climb in that attitude seems like something you'd have charts for, but&#xA;  I don't even know a term or acronym for it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because of translational lift, a helicopter requires less power to climb when flying forward than it does to hover, in or out of ground effect.  The greatest power requirement is when hovering OGE and increasing the hover height requires more power still so yes, climbing vertically OGE requires more power than any other regime.  There is no chart, or term for this that I am aware of simply because you should not do it and the POH will detail restrictions, not least, the &quot;dead mans&quot; or avoid curve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q4QB4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q4QB4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flyinghelicoptersinalaska.blogspot.co.uk/2010/04/why-dont-helicopters-go-straight-up-and.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://flyinghelicoptersinalaska.blogspot.co.uk/2010/04/why-dont-helicopters-go-straight-up-and.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only time you should ever climb vertically (a &quot;towering&quot; take-off) is when operating out of a confined area when it would not be possible to get out without clearing the trees, walls or whatever.  Some pros do it all the time, e.g. power line inspection/repairs, logging and so on but they accept a risk of operating outside of the limits and are certified and insured appropriately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The avoid curve shows the combinations of height and speed in which test pilots (i.e. the best) have demonstrated that a safe landing is possible if the engine quits.  You should not fly in the shaded area so you can see (and that chart is similar for all helicopters) that a towering take-off should never be used unless there is no alternative, and only then, for the shortest possible time.  Coming into a high hover, say 50 feet, or continuing a vertical climb OGE is prohibited by virtue of it being in the shaded area(s) of the chart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters are not always intuitive.  Many people are surprised by the fact that climbing needs less power than hovering, and the faster you go (up until that point where the parasitic power increases dramatically), the less power is required.  Imagine a car where less power was required to accelerate and go faster!&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-01T00:25:54.633" LastActivityDate="2015-11-01T00:25:54.633" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="22498" PostTypeId="1" AcceptedAnswerId="22501" CreationDate="2015-10-29T20:31:17.980" Score="10" ViewCount="1314" Body="&lt;p&gt;I live in a small city in the Southeastern United States and the county's airport has an opening for the manager. The airport is paved but no control tower, serves general aviation as well as company jets for regional businesses. They sell aviation gasoline as well as jet a, oil, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the qualification for being a good candidate for this job? Are there certifications that would be needed? Would one need to be a pilot?&lt;/p&gt;&#xA;" OwnerUserId="12046" LastEditorUserId="595" LastEditDate="2015-10-29T20:47:03.950" LastActivityDate="2017-06-01T11:05:47.803" Title="What are the qualifications for a small airport manager?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;&lt;general-aviation&gt;&lt;usa&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22499" PostTypeId="2" ParentId="22495" CreationDate="2015-10-29T21:04:18.897" Score="9" Body="&lt;p&gt;Yes and yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A certification requirement of helicopters with powered controls is that they have a manual reversion so that control can be maintained in the event of a power failure.  However, the controls can be really heavy with no power and accidents have occurred when hydraulics have failed at critical moments or pilots have lifted off with hydraulics off and have been caught by suprise with the effort needed to maintain control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The control inputs during autorotation are the same.  For any given glide, or flare, the lift required is the same powered or unpowered.  Lift is proportional to the speed of the blades, which is independent of powered or unpowered, and the angle of attack.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During autorotation, the energy (power) going into the rotors is derived from the airflow coming up through the disc. In this sense, an autorotation is still powered but the power comes from the airflow rather than the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During autorotation, since the airflow is from below, rather than above, the pitch required is lower for the same angle of attack to generate the same amount of lift.  So, the swashplate is lower in autorotation but lowering collective still decreases lift and raising it increases lift.  The primary difference is that rather than controlling lift and power, the collective controls rotor speed since increasing pitch increases the angle of attack which increases lift and therefore increases drag, slowing down the rotor.  Lowering the collective has the opposite affect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cyclic control is the same in all respects (you tilt the rotor thrust in the direction you want to go) since it increases, or decreases the pitch, and therefore the angle of attack, cyclically.  The movement of the swashplate about the X and Y axis is independent of the position of the swashplate in the Z axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pedals work in the same way too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, the only difference in the controls is the vertical position of the swashplate.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-10-29T21:04:18.897" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22500" PostTypeId="1" CreationDate="2015-10-29T21:04:51.747" Score="1" ViewCount="67" Body="&lt;p&gt;I'm on a JetBlue flight and noticed a cable running from the gate / gangway into the plane, which appeared to be labeled &quot;Cabin Temperature Probe&quot; or something to that effect.  The cable is draped over the divider in front of the first row of seats. Further, the console outside the plane appeared to have only a single yellow light (which was off), no display or additional controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this for? It seems like a sensor actually installed in the plane would be more accurate (it would work even when the door is closed). As is, I imagine the probe is picking up much more ambient air than cabin air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/uZm3h.jpg&quot; alt=&quot;probe in the cabin&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="1808" LastActivityDate="2015-10-29T21:04:51.747" Title="What is the purpose of the cabin temperature probe run from the gate?" Tags="&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-10-29T21:23:07.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="22501" PostTypeId="2" ParentId="22498" CreationDate="2015-10-29T21:15:19.280" Score="10" Body="&lt;p&gt;There are no formal qualifications required to be an airport manager -- it's not a &quot;regulated professional field&quot; in the same way as Doctors, Lawyers, or Professional Engineers.  If a person had the money they could purchase an airport and name themselves &quot;airport manager&quot; of their own facility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, managing an airport has an interesting set of challenges and could probably be described as like being the mayor of a small city with its own road infrastructure (runways, taxiways, and ramp areas), snow removal services, business districts (FBOs, restaurants, &amp;amp; other tenants), municipal services (ARFF), and utilities (airport lighting, fuel farms, drainage systems). The airport manager will also have to interface with federal agencies: The FAA/DOT at a minimum, and likely also the EPA and Homeland Security (TSA/CBP). Working with the local municipality and dealing with local residents on matters like noise abatement is also usually part of the job.&lt;br&gt;&#xA;In many ways &quot;airport manager&quot; is as much a political position as an operational one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because of the unique challenges involved in managing an airport there are degree programs specifically focused on airport management, and preference will probably be given to applicants with those degrees. Alternatively relevant operational experience (either from running an airport elsewhere or from working in other municipal departments within the county) might be enough to deem a candidate qualified.&lt;br&gt;&#xA;&lt;a href=&quot;http://www.aaae.org&quot;&gt;There are also professional organizations&lt;/a&gt; for airport executives/managers which offer independent certification for individuals.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As a pilot I would say it's advantageous for an airport manager to be a pilot (and in the case of a small airport like the one you describe it would be helpful if they were an active pilot), but being a pilot doesn't really qualify a person in any of the other key operational areas - snow removal, runway maintenance, emergency response, etc. - so while experience as a pilot or controller might be &lt;em&gt;helpful&lt;/em&gt; in that it imparts a greater understanding of the operational impact of certain decisions it would likely be viewed as a secondary qualification.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-29T21:15:19.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22502" PostTypeId="2" ParentId="22351" CreationDate="2015-10-29T22:47:39.620" Score="3" Body="&lt;p&gt;In Europe and I suspect the FAA has a similar rule, if you are flying commercially, you're allowed to fly the SID...but you need to have performance documentation on the specific airport with the specific A/C, engines and runway which will give you your climb gradient single engine and an escape route to follow in case of Engine failure. Most major company have a in house doc, others will use Flygprestanda, flightGuru etc... which will compile those calculations for you.&#xA;The short answer then is :Yes you can, provided you can demonstrate that you know which path you'll followed on SE and what will be your performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps ;-)&lt;/p&gt;&#xA;" OwnerUserId="3980" LastActivityDate="2015-10-29T22:47:39.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22503" PostTypeId="2" ParentId="22491" CreationDate="2015-10-29T23:37:59.103" Score="6" Body="&lt;p&gt;There is nothing that prevents tilt rotors from performing an autorotational landing, in theory. &lt;a href=&quot;https://en.wikipedia.org/wiki/AgustaWestland_AW609&quot;&gt;AugustaWestland AW 609&lt;/a&gt; has already &lt;a href=&quot;http://www.gizmag.com/agustawestland-aw609-autorotation-trials/31813/&quot;&gt;demonstrated this&lt;/a&gt;. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_XV-3&quot;&gt;Bell XV-3&lt;/a&gt; also did this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, V22 has not demonstrated autorotation in any practical sense. The descent rate is too high for safe landing. The failure of V 22 to autorotate is due to the high wing loading (which is ~50% high compared to the AW609) and the low inertia of the blades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer/operator has instead claimed two things- the requirement (of both engines failing together) is remote and that it can glide in any case. At the end of the glide (which is pretty steep compared with 'normal' aircraft), the structure and seats are expected to absorb the impact.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-29T23:37:59.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22504" PostTypeId="2" ParentId="22478" CreationDate="2015-10-30T00:13:01.597" Score="5" Body="&lt;p&gt;We all know the saying &quot;From High to Low, Look out below&quot;  Some were taught that this only applied to pressure differences and thus were instructed to get a new altimeter setting every 100NM or so.  This is a good recommendation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Temperature differences from standard also causes errors with the altimeter.  The same saying above holds true with temperature variations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An altimeter setting is defined as: (ref. Pilot/Controller Glossary)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The barometric pressure reading used to adjust a pressure altimeter for variations in existing atmospheric pressure or to the standard altimeter setting (29.92).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We also know there is a direct correlation between pressure and temperature and thus an altimeter setting is corrected for both pressure and temperature.  This means one thing, the altimeter error is zero at the field elevation.  As the aircraft gets climbs higher above the field, the altimeter error will increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a table in the Aeronautical Information Manual (7-2-8) that lists altimeter error due to temperature as a function of altitude (AGL) and temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/ghvx9.png&quot; alt=&quot;ICAO Cold Temperature Error Table&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the formula that will give you this table.  The formula can be found in &lt;a href=&quot;http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-menu-3092.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Canadian Aeronautical Information Manual (RAC section)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://allaboutairplanes.files.wordpress.com/2011/08/cold-temperature-correction-formula.png&quot; alt=&quot;Canadian Cold Weather Formula&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The United States Air Force has a &lt;a href=&quot;https://allaboutairplanes.wordpress.com/?attachment_id=618&quot; rel=&quot;nofollow noreferrer&quot;&gt;PowerPoint&lt;/a&gt; that discusses this topic.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The FAA has recently come out with &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2015/InFO15002.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Info 15002&lt;/a&gt; which requires pilots (after 9/17/2015) who fly into &quot;Cold Temperature Restricted Airports&quot; to correct their altitudes for colder than standard temperatures.  To determine if your airport is part of this program you must go to the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronav FAA website&lt;/a&gt; and search for Cold Temperature Restricted Airports.  There should be a link at the bottom of the page.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a graphic showing all the airports in the United States that were part of the program in February 2015.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://allaboutairplanes.files.wordpress.com/2014/12/us-map.png&quot; alt=&quot;Cold Temperature Restricted Airport - CONUS&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because Lnafziger wanted Alaska.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://allaboutairplanes.files.wordpress.com/2014/12/alaska-map.png&quot; alt=&quot;Cold Temperature Restricted Airport - Alaska&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not only is the pilot required to correct for the segment but they are also required to inform ATC of the new altitudes they will fly.  This is to ensure traffic separation with other airplanes who are not temperature correcting their altimeters.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pictures taken with permission from &lt;a href=&quot;http://allaboutairplanes.wordpress.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;All About Airplanes blog&lt;/a&gt;.  All rights reserved.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2015-11-05T02:52:03.707" LastActivityDate="2015-11-05T02:52:03.707" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22505" PostTypeId="2" ParentId="22488" CreationDate="2015-10-30T00:23:44.717" Score="0" Body="&lt;p&gt;EFAS - Inflight Weather Advisory Services (aka Flight Watch) is a special frequency in the United States on 122.0.  It uses remote communication outlets (RCO) and is typically collocated with navigational equipment.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you talk with a FSS weather briefer on EFAS you are talking with a more experience weather briefer who can provide a greater degree of accuracy with changing weather conditions.  When I took a tour or the Prescott FSS station after Lockheed Martin took over, the tour guide state the EFAS station is manned by a Level 2 weather briefer who is more knowledgeable than a Level 1 briefer who you might talk too over a regular FSS frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FSS personnel can talk to pilots over RCO and the frequency is typically found along the top of the VOR dialog box on sectional charts as well as 122.2 and 122.4.  These briefers are available to open and close flight plans, accept PIREPs and provide basic weather services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The picture below shows that you can talk with McAlester FSS on 122.1 and receive their response over the VOR 115.2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yc8dX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yc8dX.png&quot; alt=&quot;McAlister FSS Station&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-30T00:23:44.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22506" PostTypeId="1" CreationDate="2015-10-30T04:19:21.747" Score="12" ViewCount="4784" Body="&lt;p&gt;How do pilots cope with an asymmetric flap extension? What are the procedures for this type of occurrence which I suppose are similar on all aircraft?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="167" LastEditDate="2015-10-30T06:19:56.157" LastActivityDate="2017-07-31T17:26:10.363" Title="How do you cope with an asymmetric flap extension?" Tags="&lt;emergency&gt;&lt;flaps&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22507" PostTypeId="1" AcceptedAnswerId="22515" CreationDate="2015-10-30T04:26:43.127" Score="6" ViewCount="2774" Body="&lt;p&gt;Are pilots authorised to use sleeping pills to rest before long haul flight that departs at night hours? This question comes in mind as I have flown Turkish Airlines flights that depart at 2.30 at night arriving in the morning with the duration of the flight of about 8 hours. Since the pilot or the co-pilot have to be awake (I suppose, at least one of the 2..) during the flight they will have to get good rest during the day. Sleeping during the day is quite difficult and not natural and this is where my question comes from. If not, what remedies do they use?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2016-07-15T07:24:49.007" LastActivityDate="2016-07-15T07:24:49.007" Title="How do pilots get enough sleep in preparation for a long night flight?" Tags="&lt;flight-planning&gt;&lt;medical&gt;&lt;crew&gt;&lt;night-flying&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22508" PostTypeId="2" ParentId="22506" CreationDate="2015-10-30T05:07:12.247" Score="13" Body="&lt;p&gt;I'd guess the procedures probably vary considerably by class and type. If the flaps on one side broke or got stuck on the light GA plane I mostly fly, the procedure would be to just set the side you can control to the same as the side you can't control and land with that amount of flaps. You can land it with no flaps; you'll just have to land a little faster than normal and with sub-optimal visibility of the runway (but still plenty to get the plane onto it safely.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least in the planes I've flown, it would be nearly impossible for the flaps on both sides to get stuck in different positions (because both sides are mechanically connected to the flap lever,) but even that could be dealt with by using the ailerons to counter the asymmetry of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other procedure involved is to do a proper pre-flight and make sure your flaps aren't broken, loose, or damaged before you leave the ground. :)&lt;/p&gt;&#xA;" OwnerUserId="755" LastActivityDate="2015-10-30T05:07:12.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22509" PostTypeId="2" ParentId="22350" CreationDate="2015-10-30T05:10:12.007" Score="1" Body="&lt;p&gt;Balanced field length calculations by definition are the &lt;strong&gt;greater&lt;/strong&gt; of three factors.  As Lnafziger noted in his answer to the linked questions above these three factors are: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;115% All engine takeoff distance&lt;/li&gt;&#xA;&lt;li&gt;Accelerate-stop distance&lt;/li&gt;&#xA;&lt;li&gt;Accelerate-go distance&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The manufacturer will choose a $V_{1}$ speed that will all the accelerate-stop and accelerate-go distances to be as close as possible.  This reduced the takeoff distance to the lowest possible since the takeoff distance is the &lt;strong&gt;greater&lt;/strong&gt; of those three factors.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This means that our takeoff distance &lt;strong&gt;must&lt;/strong&gt; be less than certain declared distances.  See the linked questions for a discussion on declared distances.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The TORA value may or may not equal the runway length but it will never be greater than that length.  &lt;/li&gt;&#xA;&lt;li&gt;The TODA is the TORA plus a clearway.&lt;/li&gt;&#xA;&lt;li&gt;The ASDA is the TORA plus a stopway (it can be lower than the TORA value).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Using common sense, our accelerate-go distance cannot be greater than the TODA value and our accelerate-stop distance cannot be greater than the ASDA value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we take this one step further, since we have one number for takeoff and we don't know if that number is limited by the accelerate-stop or accelerate-go performance we cannot use the TODA value for the accelerate-go distance.  We must use the TORA value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, for multi-engine airplanes with balanced field length calculations we are limited to the lower of the &lt;strong&gt;TORA or ASDA&lt;/strong&gt; values for our takeoff distance.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As Aeroalias and Lnafziger pointed out, for &lt;em&gt;unbalanced field length&lt;/em&gt; calculations we can indeed use the TODA value for the accelerate-go distance and the ASDA value for the accelerate-stop distance.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;References:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.nbaa.org/ops/safety/climb-performance/videos/declared-distances.php&quot; rel=&quot;nofollow&quot;&gt;NBAA&lt;/a&gt; has some great videos on the subject.  Here is the video on &lt;a href=&quot;https://www.youtube.com/embed/yh5_FN3Rmw0&quot; rel=&quot;nofollow&quot;&gt;YouTube&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/November/Pilot/Mentor-Matters-runway-declared-distances&quot; rel=&quot;nofollow&quot;&gt;AOPA&lt;/a&gt; also has information on the subject&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-10-30T05:10:12.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22510" PostTypeId="2" ParentId="22371" CreationDate="2015-10-30T07:03:06.550" Score="2" Body="&lt;p&gt;For an airline there may be other benefits beyond direct financial profit from the sales.&lt;br/&gt;&#xA;It's a bit of customer service, allowing passengers to buy things on board they may have forgotten to pack for example.&lt;br/&gt;&#xA;And a lot of the items they have are branded, which adds marketing value as the items are often purchased as gifts for friends, family, and business associates by people who didn't have opportunity to do so before the flight.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;TBH because of the often inflated prices and (to me) unappealing selection of items I rarely buy anything unless the carrier accepts cash in some currency I have left over that's impossible to exchange back home. &lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-10-30T07:03:06.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22512" PostTypeId="5" CreationDate="2015-10-30T10:15:54.867" Score="0" Body="&lt;p&gt;The Bell Boeing V-22 Osprey is a tilt-rotor designed for cargo and personnel transport with the VTOL performance of a helicopter but much faster and more efficient forward flight. Designed for military use, it's operated by several US armed forces as well as the Japanese JSDF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Osprey is very recognisable, so it should be easy to know if your question is about the Osprey, but only use the tag if your question is specific to this type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow&quot;&gt;the Wikipedia page&lt;/a&gt; as always. It has lots of pictures.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-10-30T11:39:33.187" LastActivityDate="2015-10-30T11:39:33.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22513" PostTypeId="4" CreationDate="2015-10-30T10:15:54.867" Score="0" Body="Use on questions specific to the V-22 Osprey and its variants. The V-22 is a tilt-rotor so has many handling and aerodynamic issues specific to the type." OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-10-30T11:39:40.867" LastActivityDate="2015-10-30T11:39:40.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22514" PostTypeId="2" ParentId="22507" CreationDate="2015-10-30T10:24:08.557" Score="2" Body="&lt;p&gt;Usually, pilots (and ATC staff) are not allowed to take any sleeping pills during duty. In case they had taken a sleep aid, they are not allowed to perform the (pilot or ATC) duties for a specified time depending on the drug. &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/pharm/sleepaids/&quot; rel=&quot;nofollow&quot;&gt;According to FAA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Because of the potential for impairment, we require a minimum wait time between the last dose of a sleep aid and performing pilot or ATCS duties. This wait time is based on the pharmacologic elimination half life of the drug (half life is the time it takes to clear half of the absorbed dose from the body). The minimum required wait time after the last dose of a sleep aid is 5-times the maximum elimination half life.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, the pilots are allowed to use sleep aids occasionally for reasons such as circadian rhythm disruption in commercial air operations provided they don't operate aircraft as noted above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots use a number of ways to cope of with sleep deprivation, especially in long haul flights. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A number of non-US carriers (like Air Canada, Air New Zealand, British Airways, Emirates, Finnair, Lufthansa, Swissair, Qantas etc) allow in-seat cockpit naps under certain conditions, though FAA has not allowed this still. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, ultra-long flights allow for in-flight bunk sleep periods for (both the) pilots.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircrew are allowed strict rest periods between flights by regulation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots alternate flying duties so as to reduce fatigue.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-10-30T10:34:55.280" LastActivityDate="2015-10-30T10:34:55.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22515" PostTypeId="2" ParentId="22507" CreationDate="2015-10-30T10:26:31.920" Score="4" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;: Sleep aids cannot be used this way in the US. FAA regulates the use of such medications with a delay:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/pharm/sleepaids/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pharmaceuticals (Therapeutic Medications) Sleep Aids&lt;/a&gt;:  &lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sEFM3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sEFM3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;More on medication advice to medical examiners: &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/pharm/dni_dnf/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pharmaceuticals (Therapeutic Medications) - Do Not Issue - Do Not Fly&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Only the &lt;a href=&quot;https://en.wikipedia.org/wiki/Zaleplon&quot; rel=&quot;nofollow noreferrer&quot;&gt;zaleplon molecule&lt;/a&gt; (a &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Nonbenzodiazepine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Z-drug&lt;/a&gt;&lt;/em&gt; ⁞ &lt;a href=&quot;https://en.wikipedia.org/wiki/Hypnotic&quot; rel=&quot;nofollow noreferrer&quot;&gt;hypnotic&lt;/a&gt;) could be used in a practical manner (not publicly available in France nor likely in many other countries).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;&lt;strong&gt;Circadian rhythm&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you are referring to has got the scientific name of circadian rhythm (circa = around, diēs = day), which is the subject of an article at SkyBrary: &lt;a href=&quot;http://www.skybrary.aero/index.php/Circadian_Rhythms_%28OGHFA_BN%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Circadian Rhythms&lt;/a&gt;. About the night flights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Night operations create a host of problems for flight crews. The&#xA;  primary problem is having to work efficiently and safely at a point in&#xA;  time when the work requirements are not in synchrony with circadian&#xA;  rhythms. Under worst-case conditions, crew members must perform&#xA;  demanding tasks during the early morning hours (2 am to 6 am) when&#xA;  their biological functions and performance efficiency are at their&#xA;  lowest level. This problem cannot be quickly solved by adaptation of&#xA;  the biological clock. Complete adjustment to night work requires at&#xA;  least 21 night shifts in a row with no days off. Adjustment of the&#xA;  biological clock does not even commence until about 10 days after a&#xA;  shift change.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;&lt;strong&gt;Fatigue&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long article about &lt;a href=&quot;https://www.asma.org/asma/media/asma/pdf-policy/2009/fatigue-counters.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fatigue Countermeasures in Aviation&lt;/a&gt;, about zaleplon:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This misalignment of the sleep/wake cycle and endogenous circadian&#xA;  rhythms could be the result of shift lag, jet lag, or attempting&#xA;  sleep at other than the habitual bedtime or at the second circadian&#xA;  dip in the afternoon. For such circumstances, the U.S. Air Force and&#xA;  Army have approved the limited use of temazepam, zolpidem, and&#xA;  zaleplon. These hypnotics can optimize the quality of crew&#xA;  rest in circumstances where sleep is possible, but difficult to&#xA;  obtain.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;&lt;strong&gt;Inflight rest&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As additional information about sleep management inflight: On a 8-hour flight, usually there will be 3 pilots, and each one will be able to sleep (outside the flight deck).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air France &lt;a href=&quot;http://corporate.airfrance.com/en/press/af-447-rio-paris-cdg/inflight-rest-for-crews-long-haul-flights/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inflight rest for crews&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Air Canada &lt;a href=&quot;http://gofar.aircanada.com/en/go-far-answers/question/pilots-get-rest-long-haul-flights/&quot; rel=&quot;nofollow noreferrer&quot;&gt;When do pilots get to rest during long haul flights?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.core77.com/posts/27476/The-Part-of-the-Plane-You-Never-Get-to-See-What-Do-Cabin-Crews-Chillaxation-Spots-Look-Like&quot; rel=&quot;nofollow noreferrer&quot;&gt;What Do Cabin Crews' Chillaxation Spots Look Like?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-10-30T16:49:32.497" LastActivityDate="2015-10-30T16:49:32.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22517" PostTypeId="1" AcceptedAnswerId="22520" CreationDate="2015-10-30T12:14:15.817" Score="4" ViewCount="721" Body="&lt;p&gt;Is there any indication to the crew of the aircraft about any potential leakage of fuel from any part of the plane?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-10-30T15:46:28.343" LastActivityDate="2016-01-08T15:24:45.417" Title="Does the cockpit have an alarm to warn about fuel leakage?" Tags="&lt;cockpit&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22518" PostTypeId="1" CreationDate="2015-10-30T12:17:24.683" Score="1" ViewCount="9259" Body="&lt;p&gt;I think there are many baffles inside the shape of Fuel tank. What kind of advantage they do?  Do they help in managing the oscillations in-flight?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-10-30T12:45:34.620" Title="What is the role of baffles in Fuel Tanks?" Tags="&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-30T14:27:14.873" ContentLicense="CC BY-SA 3.0" />
  <row Id="22520" PostTypeId="2" ParentId="22517" CreationDate="2015-10-30T12:26:39.723" Score="3" Body="&lt;p&gt;In a typical trainer aircraft (in this case, a C172), you have an annunciator panel that includes a &amp;quot;Low Fuel&amp;quot; light:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/itu7O.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/itu7O.png&quot; alt=&quot;CESSNA 172&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;These lights only come on when fuel is low if the lights are functioning properly. This panel is located prominently, and is easy to notice. This is only one aircraft, but when you consider it is an entry level aircraft that is less sophisticated, it gives a baseline idea of what you could expect to see.&lt;/p&gt;&#xA;&lt;p&gt;Also, there are fuel gauges displayed with all engine instruments that will indicate accordingly. While this isn't a leak detector, pilots are trained to monitor all instruments regularly and cross check the values - which is how a leak is identified in aircraft with low amounts of technology.&lt;/p&gt;&#xA;&lt;p&gt;It is worth noting that checking the &amp;quot;LOW FUEL&amp;quot; annunciator is off is a regular checklist item that occurs before you start your actual flight.&lt;/p&gt;&#xA;&lt;p&gt;As GdD mentions in the comments - you are taught not to rely on any one instrument indication, and panel lights are no exception.&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-10-30T13:29:05.577" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22522" PostTypeId="2" ParentId="22518" CreationDate="2015-10-30T12:36:49.260" Score="5" Body="&lt;p&gt;They help in keeping the fuel from sloshing around during maneuvering. Some sloshing is impossible to avoid, but a reduction is extremely helpful in avoiding unwanted dynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a sudden pitch-up into a climb, or a sudden acceleration when the afterburners are lit: Now the fuel will rush backwards, shifting the center of gravity backwards. If this happens suddenly and the fuel starts oscillating, the aircraft would fly a wavy flightpath without pilot input. Now add the input of the pilot who tries to keep the flightpath steady, which is delayed by maybe 0.2 seconds, and add the latency of the control system, and you might have ideal conditions for pilot induced oscillations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some combat aircraft don't use baffles, but a coarse, sponge-like foam which takes up maybe 2% of the tank volume but dampens fuel oscillations very effectively.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-10-30T12:45:34.620" LastActivityDate="2015-10-30T12:45:34.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22523" PostTypeId="1" AcceptedAnswerId="22528" CreationDate="2015-10-30T13:27:14.277" Score="5" ViewCount="4958" Body="&lt;p&gt;I am studying the primary and secondary IFR instrument designations. I understand that the primary instrument is the one that closest represents your target value, and is normally the one gauge that isn't moving on the panel during the targeted maneuver (for example, in a constant rate turn, the Turn Coordinator is stabilized on a value after entry is completed and becomes primary).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fly a variable pitch prop, and I think my confusion might be a result of not flying a constant speed propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take a look at the item in red:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AjFxs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AjFxs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can someone explain why the CS Climb power primary isn't the airspeed indicator?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you are stabilized on your airspeed, wouldn't airspeed dictate the power setting you want to maintain? If you change pitch, the airspeed drops/rises and the power is changed - doesn't that make the airspeed indicator primary?  I have been taught to set power (on entry) and then monitor airspeed to make pitch adjustments. This makes the idea of a power primary confusing in stabilized descent/climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems like a confusing way to have to learn the material as I don't find I have to think about this while flying to effectively control the airplane...&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="19" LastEditDate="2016-11-11T13:23:33.990" LastActivityDate="2016-11-11T13:23:33.990" Title="Why isn't the airspeed indicator the primary instrument for power during a constant speed climb?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22524" PostTypeId="1" AcceptedAnswerId="22527" CreationDate="2015-10-30T07:20:33.690" Score="5" ViewCount="2483" Body="&lt;p&gt;On standard fixed-wing aircraft that have both ailerons and elevators, can ailerons function as elevators for pitching movement if the elevators fail? Technically it should be possible if both ailerons can rotate in the same direction simultaneously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what are the key differences and problems if the center of gravity of the aircraft was forward of the ailerons or behind the ailerons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my understanding, the farther back the control surface (which causes the pitching) is to the center of gravity, the bigger the pitching moment which results in a more stable configuration.&lt;/p&gt;&#xA;" OwnerUserId="12056" OwnerDisplayName="user155876" LastActivityDate="2015-10-30T18:00:11.020" Title="Can ailerons be used for pitch change in the event of elevator failure?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22525" PostTypeId="2" ParentId="22524" CreationDate="2015-10-30T12:57:41.443" Score="1" Body="&lt;p&gt;I am a 100-hour pilot, so I know the basics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every civilian airplane requires &lt;em&gt;decalage&lt;/em&gt;, which is an up-turning tendency.&#xA;Then if the plane is properly loaded, the center of gravity is forward of the center of lift. If there were no gravity, the plane would simply travel in a circular loop upwards.&#xA;The weight of the nose is what prevents that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why? For speed stability.&#xA;Both lift and the up-turning tendency are proportional to speed squared.&#xA;So if they go slower, the nose wins, carrying them down, which makes them go faster.&#xA;If they go faster, the wings win, carrying them up, which makes them go slower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if the elevators become frozen, and you want to nose up, just give it the gas and go faster.&#xA;Either that or lower the flaps, to get more lift.&#xA;Or you could move some weight to the rear.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: This image is to show how to make a flaperon with purely mechanical linkage:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BuzyP.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BuzyP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="395" OwnerDisplayName="Mike Dunlavey" LastEditorUserId="395" LastEditDate="2015-10-30T17:03:23.100" LastActivityDate="2015-10-30T17:03:23.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22526" PostTypeId="1" CreationDate="2015-10-30T13:46:48.687" Score="2" ViewCount="1069" Body="&lt;p&gt;The parameters are:&#xA;MTOW, MLW, MZFW, OEW, maximum fuel weight, fuel flow rate and true airspeed. Measured in lbs and kts. Not given drag so unsure how to apply Breguet equation. Trying to construct a payload range diagram! &lt;/p&gt;&#xA;" OwnerUserId="12057" LastActivityDate="2018-04-14T15:39:03.817" Title="How do I calculate aircraft range with these parameters?" Tags="&lt;airspeed&gt;&lt;drag&gt;&lt;range&gt;&lt;payload&gt;&lt;weight&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22527" PostTypeId="2" ParentId="22524" CreationDate="2015-10-30T14:00:37.507" Score="9" Body="&lt;p&gt;If the ailerons could be moved in the same way on both wings, the linkage between both is broken and they would float up near their maximum negative (trailing edge up) deflection angle. Even a hydraulic aileron booster would not help, since here still an interlink between both ailerons exists to keep actuation forces down. Only in a fly-by-wire aircraft with fully powered aileron actuators could the control system be programmed to allow symmetric deflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effectivity of such a means of pitch control is very low, and only wing sweep can help to make it useable. Any pitch control input will change lift on the outer wing, and pitching up would mean a loss of lift and result in a plunging motion of the aircraft. If that happens on landing, when the pilot uses to pull the stick to raise the nose gradually, the resulting ground contact will be rather early and bumpy. Pilots of flying wings know this; they are very careful with their pitch control during a flare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASW_20&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASW-20 glider&lt;/a&gt; had crashed a couple of years ago because the pilot had forgotten to connect the elevator linkage, &lt;a href=&quot;https://en.wikipedia.org/wiki/Gerhard_Waibel_(engineer)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gerhard Waibel&lt;/a&gt; flew to the glider club and demonstrated how to fly the ASW-20 with flaps for pitch control alone. The downside is a much reduced speed range and a high landing speed, because you need to reduce camber in order to pitch up, but it works. Since the flap span is higher than the aileron span, I would strongly recommend to rely on the flaps for pitch control when your elevator stops working if flaps are installed. They also do not need any modification to work as pitch controls since they are rigged to move symmetrically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the engines are mounted low or high, &lt;a href=&quot;https://aviation.stackexchange.com/search?q=Control%20means%20to%20be%20able%20to%20vary%20the%20forces%20which%20act%20on%20an%20airplane%2C&quot;&gt;their thrust can also be used for pitch control&lt;/a&gt;. This was used on several occasions to bring an airliner down &lt;a href=&quot;https://aviation.stackexchange.com/questions/21460/why-could-these-aircraft-not-prevent-total-hydraulic-failure/21465?s=1%7C0.2407#21465&quot;&gt;after all hydraulic circuits had failed&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;Mike Dunlavey insists I should mention flaperons. He is right, they are possible with mechanical linkage only, but you will find them only on wings which have flaps anyway. All modern gliders with flaps will also move the ailerons in sync with the flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But they are the worst choice for pitch control. For one, they are on the part of the wing with the smallest chord. Their lift change will go with the &lt;strong&gt;smallest&lt;/strong&gt; pitch moment change of all controls except the rudder, so it would be &lt;strong&gt;much&lt;/strong&gt; better to use the flaps for pitch control. That the ailerons do move with the flaps will have little effect. Besides, well designed flaperons will have less deflection change for a given flap change so the spanwise lift distribution will stay close to the optimum. This will make them &lt;strong&gt;even less&lt;/strong&gt; effective than the flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I choose not to mention them to make the answer concise. But I'm afraid short answers are not appreciated anymore.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-10-30T18:00:11.020" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="22528" PostTypeId="2" ParentId="22523" CreationDate="2015-10-30T14:17:35.983" Score="3" Body="&lt;p&gt;Airspeed indicator is a primary instrument for pitch in that row, so it can't be also primary for power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point of constant &lt;em&gt;speed&lt;/em&gt; climb is that you select power and maintain speed with pitch, getting whatever climb rate that power can support. Most often the point is selecting &quot;climb&quot; or &quot;maximum continuous&quot; power and climbing as fast as possible without overstressing the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only difference with variable pitch prop is that it decouples rpm from engine power, so you can't use rpm and are left with manifold pressure only (for piston; I am not sure what the correct reference is for turbine).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that two lines lower there is a constant &lt;em&gt;rate&lt;/em&gt; climb and there airspeed is primary reference for power, because there you adjust pitch to maintain desired vertical speed and power to maintain airspeed. But since you shouldn't use more power than the recommended climb setting anyway, the constant speed climb gives you better performance.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-10-30T14:22:59.000" LastActivityDate="2015-10-30T14:22:59.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22529" PostTypeId="2" ParentId="22526" CreationDate="2015-10-30T14:40:10.733" Score="3" Body="&lt;p&gt;If the fuel flow rate and the true airspeed are for the same &lt;a href=&quot;https://aviation.stackexchange.com/questions/8266/how-to-find-polar-curves-of-airliners&quot;&gt;polar&lt;/a&gt; point, the answer is easy. You cannot, however, determine if this is your maximum range because you do not know any other points of the polar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your fuel consumption is MTOW - MLW. The flow rate will give you the flight time when you divide the fuel by the flow rate. With the flight time you can calculate the range by multiplying it with the airspeed. Hint: Convert all data into metric first so you don't screw up the calculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum range can be done the same way using MTOW - MZFW for the fuel mass. MZFW - OEW will tell you how much payload remains at this point. The only impossible part is the transfer range point - use the maximum range and assume that the aircraft will fly as far with a lower take-off mass as with MTOW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Breguet equation will not work in this case.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-10-30T14:40:10.733" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22530" PostTypeId="2" ParentId="22517" CreationDate="2015-10-30T15:14:14.483" Score="2" Body="&lt;p&gt;There is no special indicator or warning about a fuel leak because it would be difficult to automatically detect a fuel leak with any certainty (fuel flow sensors are not super accurate, nor are fuel quantity sensors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots of small, single tank airplanes must rely on reading the fuel quantity indicators periodically and &quot;knowing&quot; how much fuel should be left and how much is actually left. Big discrepancies indicate a possible fuel leak.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots of bigger, multi-tank airplanes check for (and, on more sophisticated airplanes, are warned about) fuel imbalances between tanks. A fuel imbalance again, indicates a fuel leak as it is very very unlikely that the same quantity has leaked from both tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find further info about fuel leak detection on Airbus airplanes &lt;a href=&quot;http://www.oaviao.com/pesquisa_codigo_empresas/manuais_voo/performance_airbus/fuel_leaks.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2122" LastEditorUserId="2122" LastEditDate="2016-01-08T15:24:45.417" LastActivityDate="2016-01-08T15:24:45.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22531" PostTypeId="2" ParentId="22506" CreationDate="2015-10-30T16:13:24.307" Score="11" Body="&lt;p&gt;This will vary between small planes and large planes as a result of the flap extension mechanisms and how they can possibly break. This recently happened to my instructor and we had a long discussion about it so... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before we dive in, it should be noted that the FAA recommends that while in the traffic pattern you do not extend the flaps while banking, in the event of an asymmetrical extension it may push you further into the turn.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In smaller planes (GA sized stuff) there are 2 basic flap mechanisms, electric and mechanical. The common &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee%5C&quot; rel=&quot;noreferrer&quot;&gt;Piper Cherokee&lt;/a&gt; line (all the way up through the early saratogas) employed a Johnson bar and all mechanical flaps. On the contrary Cessna moved the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;noreferrer&quot;&gt;172 to electrically&lt;/a&gt; driven flaps early on in its production. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for what to do this will depend on how it fails. In the Piper there are retract springs in the flaps so if the extension mechanism fails the flap will remain in the retracted position. Generally what fails on the pipers is the bolt that holds the push rod onto the flap or the nut comes off due to a faulty pin although the cables can fail as well. The rod looks something like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XkVG9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XkVG9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://motoplaneparts.com/listing.php?pid=78442&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit:&lt;/em&gt; I went flying this morning and got a picture of the flap pushrod joint on the Piper Warrior I was flying to show it in action. Here the flaps are fully deployed (3 notches) during my preflight check. As you can see checking that joint is critical, and you should always inspect to make sure the pin is properly in place through the nut. In this case you are looking at the head of the pin so its a bit hard to see but its there.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gkK6B.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gkK6B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case generally speaking releasing the Johnson bar will retract the other flap and you will make a no flap landing (runway provided). In this instance if you have the fuel it may be advised to divert to an airport with a longer runway. You should also practice some no flap landings during you training for this very reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the electric planes if any of the extension mechanisms break and you can still retract the flaps adhere to the procedure above. However in this case you could also have a drive motor failure or other electrical issues. For this you may be stuck with your flaps in a partially extended state. Some amount of aileron deflection will be required and you should expect higher landing speeds. Again diverting to a longer/wider runway may help. Care should be taken in the pattern turns in this case as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the redundancy in commercial airliner systems this is less of an issue for larger planes. On top of that since large planes generally have multiple engines you can take advantage of differential power settings as well as cross control. Large planes also generally have more than one set of flaps that are often powered by multiple sets of hydraulic pistons which are unlikely to all fail in tandem. While you can have an asymmetrical extension on a commercial airliner chances are it would not be like that of a GA plane where you run the risk of a full extension on one side and no extension on the other.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XjxsR.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XjxsR.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.b737.org.uk/pilotnotes.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-10-31T19:36:41.520" LastActivityDate="2015-10-31T19:36:41.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22532" PostTypeId="2" ParentId="22466" CreationDate="2015-10-30T16:25:47.723" Score="2" Body="&lt;p&gt;Two additional ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A little metal box with a slot at the top where your expected to shove some dollar bills in&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some airports collect landing fees by sending you a bill to the address in the FAA database. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-10-30T17:14:43.977" LastActivityDate="2015-10-30T17:14:43.977" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22533" PostTypeId="2" ParentId="16495" CreationDate="2015-10-30T16:57:36.063" Score="0" Body="&lt;p&gt;You have to remember the era in which the aircraft was designed.  The engines weren't as powerful so they needed four to get airborne and four to fly long haul over-water routes. There are engines now that could do the job in pairs but the 747 would need to be drastically redesigned because among other problems the wing is too low to accommodate the monster engines on planes like the 767 and 777.  What Boeing should reconsider was an aborted 3-engine design like a big 727.  They looked at it once back in the 60's but the engines weren't there yet.  Now would be a good time to reconsider.  &lt;/p&gt;&#xA;" OwnerUserId="12059" LastActivityDate="2015-10-30T16:57:36.063" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22534" PostTypeId="1" AcceptedAnswerId="22543" CreationDate="2015-10-30T17:11:55.253" Score="1" ViewCount="852" Body="&lt;p&gt;What is the main difference between Class C and B Radar Service?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class C service provides approved separation between IFR and VFR&#xA;  aircraft, and sequencing of VFR aircraft to the primary airport. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Class B service provides approved separation of aircraft based on IFR, VFR,&#xA;  and/or weight, and sequencing of VFR arrivals to the primary&#xA;  airport(s).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does &lt;em&gt;approved&lt;/em&gt; mean? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastActivityDate="2015-10-30T19:04:33.097" Title="What is the main difference between Class C and B Radar Service?" Tags="&lt;airspace&gt;&lt;radar&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22535" PostTypeId="1" CreationDate="2015-10-30T17:21:49.327" Score="12" ViewCount="2955" Body="&lt;p&gt;I got my 3rd Class Medical for a Private Pilot certificate in May 2013 at the age of 39.  I'm now 41.  Does the 60 month rule apply to my certificate or do I need to retest under the 24 month rule for over 40 year olds?&lt;/p&gt;&#xA;" OwnerUserId="12060" LastEditorUserId="62" LastEditDate="2016-07-06T17:47:51.833" LastActivityDate="2016-07-06T17:47:51.833" Title="What is the expiration period for a 3rd class medical certificate?" Tags="&lt;pilot-certification&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22536" PostTypeId="2" ParentId="22535" CreationDate="2015-10-30T17:32:24.710" Score="13" Body="&lt;p&gt;According to the table in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?type=simple;c=ecfr;cc=ecfr;sid=85f2f758c7572cf6fd784c355d1c55a1;idno=14;region=DIV1;q1=61.23;rgn=div8;view=text;node=14%3A2.0.1.1.2.1.1.17&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.23 (d)&lt;/a&gt;, the expiration date of your medical is based on your age &amp;quot;on the date of examination for your most recent medical certificate.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;So, if you were 39 on the date of the examination, you're good for 60 months.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;There is a possibility that the requirement to renew 3rd class medicals may go away completely soon. On Dec 15, 2015, &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/December/15/Full-Senate-passes-medical-reform&quot; rel=&quot;noreferrer&quot;&gt;the U.S. Senate passed the &amp;quot;Pilot's Bill of Rights 2&amp;quot;&lt;/a&gt;. The bill would still need to be passed by the House and signed by the President before it would take effect. As of Dec 15, it had 152 co-sponsors of both parties in the House. According to AOPA:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Under the medical reforms of Pilot's Bill of Rights 2, most pilots who have held a valid third class medical, either regular or special issuance, within 10 years of the legislation’s enactment would never need to get another FAA medical exam. The rule would apply to pilots flying VFR or IFR in aircraft weighing up to 6,000 pounds and carrying up to five passengers at altitudes below 18,000 feet and speeds up to 250 knots.&lt;/p&gt;&#xA;&lt;p&gt;Pilots who develop certain medical conditions, including a small list of specific cardiac, mental health, or neurological conditions, will have to get an FAA special issuance medical one time only, significantly reducing the time and money spent navigating the FAA’s medical bureaucracy.&lt;/p&gt;&#xA;&lt;p&gt;For pilots who have not had a valid medical in the past 10 years and those who have never applied for and received a medical certificate, a one-time third class medical certification by an aviation medical examiner will be required. After a pilot has been medically certified once, either through the regular or special-issuance processes, he or she will also be able to fly indefinitely without needing to go through the FAA medical certification process again.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-17T17:35:20.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22537" PostTypeId="1" CreationDate="2015-10-30T18:01:00.887" Score="1" ViewCount="252" Body="&lt;p&gt;My aunt recently was going on a flight home and she boarded the flight, but her flight was delayed due to frost on the aircraft. She noticed this crane like device above the aircraft wing during the removal process. How do they remove frost off an airliner?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="998" LastEditDate="2015-11-03T13:11:02.960" LastActivityDate="2015-11-03T13:11:02.960" Title="What is the process to remove frost off an airliner?" Tags="&lt;icing&gt;&lt;anti-ice&gt;&lt;cold-weather&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-10-30T19:50:26.620" ContentLicense="CC BY-SA 3.0" />
  <row Id="22538" PostTypeId="1" CreationDate="2015-10-30T18:06:51.673" Score="1" ViewCount="127" Body="&lt;p&gt;I'm just about to start on my first solo and was informed by my CFI that I need to have renter's insurance at a cost of about $180/year.  I looked on AOPA for this insurance and confirmed that the prices is correct if I choose no coverage for &quot;liability for damage to non-owned aircraft&quot;.  What are the factors I should consider in making the decision to add/not add this other level of coverage?&lt;/p&gt;&#xA;" OwnerUserId="12060" LastEditorUserId="19" LastEditDate="2016-11-01T11:45:49.523" LastActivityDate="2016-11-01T11:45:49.523" Title="What factors should be considered when taking private pilot renter's insurance?" Tags="&lt;renters-insurance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22539" PostTypeId="2" ParentId="22537" CreationDate="2015-10-30T18:10:16.007" Score="2" Body="&lt;p&gt;Frost is removed through the application of (typically) Type I de-ice fluid (&lt;a href=&quot;https://aviation.stackexchange.com/a/1724/258&quot;&gt;information about de-/anti-ice fluids&lt;/a&gt;). Fluid application is generally from a truck with a lift so that the operator can spray the aircraft from above. The fluid is generally hot, diluted with water and under pressure so you'll see lots of steam coming off of the fluid spray. The truck will drive around the airplane spraying the wings, tail and fuselage as necessary to completely remove snow, ice and frost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports have static mounted de-ice towers that are more like cranes and some operators have automated trucks where there is no operator in the lift and they can do the whole operation from the cab of the truck.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-10-30T18:14:55.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22540" PostTypeId="2" ParentId="22538" CreationDate="2015-10-30T18:31:06.947" Score="1" Body="&lt;p&gt;Ignoring what you should and should not have in terms of coverage for your self there are some facts to note about getting gap insurance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to speak with your flight school and ask them what &lt;strong&gt;they require you to have&lt;/strong&gt; as every flight school could be insured differently. For example, when I got my renters insurance I had to have 10K of aircraft damage coverage as the flight schools insurance did not kick in until then. Had anything happened I would have been responsible for the 0-10K worth of damage. In this case you would want coverage for damage to the aircraft. If the flight school has insurance on any and all damage you may not need it on your insurance.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-10-30T18:31:06.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22541" PostTypeId="1" AcceptedAnswerId="22546" CreationDate="2015-10-30T18:48:11.060" Score="12" ViewCount="7041" Body="&lt;p&gt;I was wondering why the F-35 engine is exposed. The F-22, F-16 and the YF-23 Black Widow have the exhaust nozzles of their engines blended flush with the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(YF-23 Black Widow)&lt;a href=&quot;https://i.stack.imgur.com/H2rmG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H2rmG.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(F-35)&lt;a href=&quot;https://i.stack.imgur.com/LpwFE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LpwFE.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The YF-23 Black Widow clearly has two engines which are indented into the plane. However the F-35 has one engine which is exposed at the back. So I have two questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Why does the F-35 have only one engine unlike the older models?&lt;/li&gt;&#xA;&lt;li&gt;Why is the F-35's engine exhaust nozzle clearly more exposed to bullets and rockets than older models?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12062" LastEditorUserId="15637" LastEditDate="2016-11-23T01:00:20.587" LastActivityDate="2019-04-20T09:59:38.427" Title="Why is the F-35 engine nozzle exposed?" Tags="&lt;military&gt;&lt;yf-23&gt;&lt;engine-placement&gt;&lt;f-35&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22542" PostTypeId="1" CreationDate="2015-10-30T18:59:37.150" Score="4" ViewCount="1911" Body="&lt;p&gt;I am a librarian looking for sources of information to help answer the following questions for one of our researchers: 1. what avionics systems are interfaced with ACARS and 2. how is the interaction between ACARS and these systems designed to occur in practice? As I am not very familiar with this subject, any information or pointers to information would be appreciated.&lt;/p&gt;&#xA;" OwnerUserId="12063" LastActivityDate="2018-12-07T18:26:50.570" Title="What avionics systems are interfaced with ACARS?" Tags="&lt;avionics&gt;&lt;acars&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22543" PostTypeId="2" ParentId="22534" CreationDate="2015-10-30T19:04:33.097" Score="1" Body="&lt;p&gt;The term is not &quot;approved&quot;, it is the complete phrase &lt;code&gt;Approved Separation&lt;/code&gt;. This is the standard FAA term for what was previously called either &lt;code&gt;standard separation&lt;/code&gt; or &lt;code&gt;radar separation&lt;/code&gt;, and means &quot;separation in accordance with the applicable minima in [&lt;a href=&quot;http://www.faa.gov/regulations_policies/orders_notices/index.cfm/go/document.information/documentID/1023549&quot; rel=&quot;nofollow&quot;&gt;FAA Order 7110&lt;/a&gt;]&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The separation minima are further defined in the JO 7110 family of FAA Air Traffic Control orders, which you can find linked from the page above.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-10-30T19:04:33.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22544" PostTypeId="2" ParentId="22541" CreationDate="2015-10-30T19:36:07.550" Score="15" Body="&lt;p&gt;The answer to both of your questions lies in the vertical takeoff and landing (VTOL) capability of the F-35.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to provide vertical thrust, the rear part of the engine rotates downward. This is much easier to accomplish if the engine exhaust is not kept on top of the plane, as in your YF-23 example. This rotating ability is also much easier to accomplish if there is only a single engine. With two engines, they would both have to rotate downward and drive the lift fan together. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-32&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing X-32&lt;/a&gt;, which was competing against the X-35 for the Joint Strike Fighter contract, also opted for a &lt;a href=&quot;https://aviation.stackexchange.com/q/15568/1696&quot;&gt;single engine design&lt;/a&gt; for similar reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your impression that the YF-23 protects the engines more doesn't really apply to things like bullets. Although the engines on a fighter are buried more in the fuselage than a &lt;a href=&quot;https://aviation.stackexchange.com/q/15354/1696&quot;&gt;typical modern airliner&lt;/a&gt;, they are still not protected much from the top or bottom, regardless of the configuration. If shrapnel is hitting the plane, protecting the engines will not solve all of your problems. You will notice that planes like the A-10 that specifically are designed for withstanding damage do not go to great lengths to hide the engines. Planes like the B-2 and YF-23 hide the engine exhaust for &lt;a href=&quot;https://aviation.stackexchange.com/q/21624/1696&quot;&gt;stealth reasons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-10-30T19:44:34.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22545" PostTypeId="2" ParentId="19604" CreationDate="2015-10-30T19:36:31.813" Score="1" Body="&lt;p&gt;The answer is more of a question. Why retire a fighter jet that can still outmatch fighter jet's today. The F-16 is a reliable tested aircraft. It's had years of edits made to it to make it the best of the best.&lt;/p&gt;&#xA;" OwnerUserId="12062" LastActivityDate="2015-10-30T19:36:31.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22546" PostTypeId="2" ParentId="22541" CreationDate="2015-10-30T19:39:37.403" Score="23" Body="&lt;p&gt;The F-22 is intended (and the competing YF-23 was intended) to be an air superiority fighter to replace the F-15.  The F-15 was a twin-engine model, as was the F-4 Phantom that it replaced.  Twin engine planes have excellent &quot;survivability,&quot; meaning they can take a lot of hits and still stand a chance of making it home (you can lose an entire engine and still stay airborne).  They also are much higher-performance.  The F-15 can takeoff, stand on its tail and climb vertically to over 40k feet.  I've seen F-16s do something similar but they couldn't climb as high and they couldn't carry as much fuel and/or armaments while doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35 is intended to be a replacement for the single-engine F-16.  The F-16 is a capable workhorse but it's more of a budget, multi-role aircraft, meaning it was designed, from the get-go, to do some air superiority AND some ground attack, operating on a tighter budget.  We have considerably more F-16s in the Air Force inventory than we've ever had (or will have) F-15s and/or F-22s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-15 used the same engine as the F-16 (two to choose from: either the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_F100&quot;&gt;P&amp;amp;W F100&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_F110&quot;&gt;GE F110&lt;/a&gt;), but two of them.  When I was in the Air Force&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;F-15's cost about USD 50 million &lt;/li&gt;&#xA;&lt;li&gt;F-16's cost about USD 35 million&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Two engines and a larger, heavier airframe (albeit less sophisticated) added up to a significant price premium.  In air combat, above 25k feet, my money would be on the F-15.  At altitudes below 25k feet, my money is on the F-16.  With an inherently unstable airframe and a computerized fly-by-wire system to tame it, the F-16 was wickedly maneuverable.  The increased power of two engines on the F-15 working against the greater weight really loses the advantage at lower altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;buried&quot; engines in the F-22/YF-23 are trying to improve the stealth characteristics.  The F-22's thrust vectoring, coupled with twin engines, make it more stealthy than the F-117 and faster and more maneuverable that the F-15 or the F-16.  The YF-23 was arguably faster, but less maneuverable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35 is intended to cost less than the F-22 (debatable as to whether that will be the final case).  And certain &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II#F-35B&quot;&gt;models of the F-35&lt;/a&gt; are capable of a trick the F-22 simply can't match: STOVL.  It can do a Short TakeOff and Vertical Landing.  For the latter, the rear nozzle pivots downward 90% and a &quot;lift fan&quot; opens up in the forward fuselage.  The F-22 was never intended to be able to do this.  &quot;Burying&quot; the rear nozzle AND trying to do that would add a LOT of weight (and additional cost) to the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastActivityDate="2015-10-30T19:39:37.403" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22547" PostTypeId="2" ParentId="22541" CreationDate="2015-10-30T20:33:15.067" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why does the F-35 have only one engine unlike the older models&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The USMC wanted the aircraft to have S/VTOL capability. This meant that the aircraft should have a single large engine as the best configuration would be to have a single engine with swiveling nozzle aft of center of gravity for supersonic flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having multiple engines in a VTOL aircraft is problematic- The same reason &lt;a href=&quot;https://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot; rel=&quot;nofollow noreferrer&quot;&gt;Harrier&lt;/a&gt; and Yak-36 has single engines (Yak-36 had smaller engines purely for takeoff, but had an automatic ejection mechanism). Loss of a single engine in a multiple engine configuration will result in uncommanded roll during (vertical takeoff and landing).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The F-35 engine is one of the most most powerful military engines out there. Improvements in engine technology have made the aircraft engines more reliable compared to the older models, so dual engines are not a requirement anymore except in some special cases. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why is the F-35's engine clearly more exposed to bullets and rockets than older models&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I think you're talking about the nozzle being visible. All modern combat aircraft engines are buried in the fuselage for various reasons. The nozzle is exposed in case of F-35 as it has to swivel for VTOL.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hvgBr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hvgBr.jpg&quot; alt=&quot;F-35 VTOL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: jeffhead.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this configuration is similar to &lt;a href=&quot;https://en.wikipedia.org/wiki/Yakovlev_Yak-141&quot; rel=&quot;nofollow noreferrer&quot;&gt;Yak-141&lt;/a&gt; (which again had two lift engines), another VTOL aircraft (Lockheed Martin worked with Yakolev during the JSF competition).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;F-22 nozzle is exposed- This is a result of the thrust vectoring. YF-23 and other stealth aircraft (like B-2) had nozzles above the fuselage to reduce IR signature from below.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-30T20:33:15.067" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22549" PostTypeId="1" CreationDate="2015-10-31T03:45:42.797" Score="9" ViewCount="3993" Body="&lt;p&gt;On many flights, I was told that a life jacket is under my seat and safety card is in the pocket in front. Is there any regulation that ensures that life jackets and safety cards are on-board on all flights?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="595" LastEditDate="2015-10-31T09:42:11.190" LastActivityDate="2016-08-04T02:19:11.987" Title="Is there any regulation to ensure that life jackets and safety cards are on-board?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22550" PostTypeId="2" ParentId="22549" CreationDate="2015-10-31T04:17:21.890" Score="1" Body="&lt;p&gt;The UK Air Navigation Order contains specific requirements in &lt;a href=&quot;https://www.caa.co.uk/docs/1672/srg_gad_Appendix%2010b%20revised.pdf&quot; rel=&quot;nofollow&quot;&gt;Appendix 10&lt;/a&gt;, based on ICAO recommendations. You won't have to look very far to find similar requirements specified by the regulatory authorities in any major country.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;6.3.2.1 Single-engined aeroplanes.&lt;br&gt;&#xA;  Recommendation . - All single-engined landplanes when flying en route over water beyond&#xA;  gliding  distance from the shore should carry one life jacket or&#xA;  equivalent individual floatation device for  each person on board,&#xA;  stowed in a position easily accessible from the seat or berth of the&#xA;  person  for whose use it is provided.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;6.3.3  All aeroplanes when operated on extended flights over water shall be equipped with:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a)  when the aeroplane may be over water at a&#xA;  distance of more than 93 km (50 NM) away from  land suitable for&#xA;  making an emergency landing:  1) one life jacket or equivalent&#xA;  individual floatation device for each person on board, stowed in a &#xA;  position easily accessible from the seat or berth of the person for&#xA;  whose use it is provided;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b)  when over water away from land suitable&#xA;  for making an emergency landing at a distance of more  than 185 km&#xA;  (100 NM), in the case of single-engined aeroplanes, and more than 370&#xA;  km (200  NM), in the case of multi-engined aeroplanes capable of&#xA;  continuing flight with one engine  inoperative:  1)  life-saving rafts&#xA;  in sufficient numbers to carry all persons on board, stowed so as to&#xA;  facilitate  their ready use in emergency, provided with  such&#xA;  life-saving equipment including means of  sustaining life as is&#xA;  appropriate to the flight to be undertaken; and  2)  equipment for&#xA;  making the pyrotechnical distress signals described in Annex 2.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user11933" LastEditorDisplayName="user11933" LastEditDate="2015-10-31T04:22:32.900" LastActivityDate="2015-10-31T04:22:32.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22552" PostTypeId="2" ParentId="22489" CreationDate="2015-10-31T09:04:04.770" Score="-4" Body="&lt;p&gt;This is anti-ice system. Hot air is blown in this holes and ice/snow not settle in jet engine.&lt;/p&gt;&#xA;" OwnerUserId="12055" LastActivityDate="2015-10-31T09:04:04.770" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22553" PostTypeId="2" ParentId="19360" CreationDate="2015-10-31T09:14:51.557" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;http://www.nbcnews.com/id/9990495/ns/business-us_business/t/boeing-breaks-record-longest-nonstop-flight/#.VjSTcnUle70&quot; rel=&quot;nofollow&quot;&gt;longest official non-stop flight&lt;/a&gt; by a commercial jet was a 777-200LR flight  from Hong Kong to London in 2005 (without passengers). It was 13,422 miles (11,768 nm, more than 21,000 km). &lt;/p&gt;&#xA;" OwnerUserId="12055" LastEditorUserId="1289" LastEditDate="2015-10-31T10:14:58.310" LastActivityDate="2015-10-31T10:14:58.310" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22554" PostTypeId="1" AcceptedAnswerId="22557" CreationDate="2015-10-31T09:31:07.717" Score="1" ViewCount="1329" Body="&lt;p&gt;What i mean by structure is (different composite materials and aluminum).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the cons in terms of time required to test the full body of the aircraft (B747 for example) in C and D checks ?   &lt;/p&gt;&#xA;" OwnerUserId="12014" LastEditorUserId="12014" LastEditDate="2015-10-31T09:38:51.287" LastActivityDate="2015-10-31T11:47:46.790" Title="What are the advantages/disadvantages of ultrasonic in aircraft structure inspection?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22555" PostTypeId="2" ParentId="19360" CreationDate="2015-10-31T10:17:29.037" Score="5" Body="&lt;p&gt;The vertical axis starts at 350 Klbs since the Boeing 777 is made to transport payload, not just itself. Any operator will be interested more in the upper part of the diagram, because only then the aircraft will earn money. This explains the gap of 30 Klbs - the people for whom this chart was made are simply not interested in the range without payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The range varies with flight parameters, and the upper left corner shows the most important ones, albeit in quite imprecise terms. If the flight speed is reduced, range will become higher until the aircraft flies at &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623?s=27%7C0.0368#3623&quot;&gt;optimum range conditions&lt;/a&gt;. Airlines like to fly their aircraft faster that that to optimize transport performance (the maximum product of speed and payload relative to operating cost). If power extraction and air condition are run at their bare minimum, again less fuel will be needed per mile of flight. Flown this way, the 777 will easily fly more than 10500 nm with a zero-fuel weight (OEW + payload) of 350,000 lbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To eke out the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3367/how-do-airliners-get-from-the-factory-to-the-client-if-the-aircraft-does-not-hav/3369?s=2%7C0.1593#3369&quot;&gt;maximum possible range&lt;/a&gt;, &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a178559.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;high-density fuel is used&lt;/a&gt; and the aircraft is flown at an &lt;a href=&quot;https://aviation.stackexchange.com/questions/4967/how-can-you-find-the-best-altitude-for-range-or-speed/4970#4970&quot;&gt;optimum altitude&lt;/a&gt; and speed for range. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777#Longer-range_models&quot; rel=&quot;nofollow noreferrer&quot;&gt;records which have been set this way&lt;/a&gt; (11,664 nm for the 777-200ER), however, are of &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_length&quot; rel=&quot;nofollow noreferrer&quot;&gt;little relevance&lt;/a&gt; to everyday operation. The longest commercial flight of that type will be the Dubai-Panama City connection of 7,463 nm which Emirates will begin to serve on February 1, 2016.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-10-31T10:36:45.557" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22556" PostTypeId="1" AcceptedAnswerId="22566" CreationDate="2015-10-31T11:09:03.007" Score="4" ViewCount="434" Body="&lt;p&gt;I am trying to understand the af447 incident, more precisely, how a professional pilot having an attitude indicator available failed to understand that the angle of attack was too high. Was it that the angle of attack may be too high at the horizontal attitude, or close to that? As I understand, the aircraft stalled due to pilot error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the longer range it cannot be just a free fall; the air friction would stabilize even a round ball to some stable falling velocity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing the downward velocity, as well as forward velocity, we can compute the angle of attack for horizontal attitude, and various different attitudes. Seems that if it falls with the same speed as it moves forward, the angle of attack would be 45 degrees just for a normal horizontal orientation. Is this situation realistic?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="8730" LastEditDate="2015-10-31T15:44:35.543" LastActivityDate="2016-11-12T19:52:36.577" Title="How much can falling down due to a stall influence the angle of attack?" Tags="&lt;stall&gt;&lt;angle-of-attack&gt;&lt;af447-accident&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22557" PostTypeId="2" ParentId="22554" CreationDate="2015-10-31T11:47:46.790" Score="2" Body="&lt;p&gt;Ultrasonic inspection is perhaps the most widely used inspection procedures in aerospace to detect subsurface anomalies. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Portability- A number of portable ultrasonic equipment are available, which are very simple and are widely used.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The detection depth for flaws is far superior compared to most other NDT methods.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It can be used for detecting flaws even if only one surface of the part is accessible (simply use pulse echo method).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The results are more or less instantaneous- Usually there is no waiting time involved as the results are displayed in a screen.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The time required for preparation is very less; usually the part is cleaned and the couplant applied; after the inspection, it can simply be wiped off. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, just like any other (NDT) method, this too has its own share of disadvantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It is very difficult to use this method for parts which are very thin- for e.g. the aircraft skin because of the dead zone, though this can be overcome by using higher frequencies or immersion technique; in most cases of aircraft checks, this may not be an option. Also, it cannot be used for irregular and non-homogeneous parts (At-least, not the portable methods).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The method does not detect flaws that are oriented parallel to the wave propagation.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The material must be characterized prior to inspection. As the returning  signal is affected by attenuation within the material, comparisons can be made only if a similar (defective and good) specimen of same material is characterized first.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Usually, Ultrasonic method requires a trained operator for interpretation of the results.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As far a full aircraft is considered, only some critical parts are tested using ultrasonic (or other NDT) methods. There is no way to check the entire aircraft except by thorough visual inspection.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-31T11:47:46.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22558" PostTypeId="2" ParentId="22556" CreationDate="2015-10-31T12:43:56.893" Score="0" Body="&lt;p&gt;Not very, I'm afraid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all,it is the angle of attack (once it goes beyond a certain value) that influences (causes) stall and not the other way around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're correct that any body will reach terminal velocity while falling through atmosphere. But the stalled aircraft is not a free falling body- the engines are still producing thrust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is the stalled aircraft rarely falls like a stone- the pilot is trying to regain control; the aircraft usually rolls or enters into a spin. Depending on the condition, the nose dips, decreasing the angle of attack. The only way for the aircraft to follow a trajectory described by you is if the pilot is holding the wing at a stalled attitude the whole way down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in a (highly unlikely) case where the aircraft falls so that the horizontal and vertical velocities are the same, it will be the trajectory that will be at $45^{\circ}$, not the angle of attack, which can be any value be over the stalling angle.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-10-31T12:43:56.893" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22562" PostTypeId="5" CreationDate="2015-10-31T14:27:45.170" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.ntsb.gov/doclib/reports/2010/AAR1003.pdf&quot; rel=&quot;nofollow&quot;&gt;Official NTSB report (PDF)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-31T14:27:45.170" LastActivityDate="2015-10-31T14:27:45.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22563" PostTypeId="4" CreationDate="2015-10-31T14:27:45.170" Score="0" Body="The January 15, 2009 accident involving the ditching of US Airways flight 1549 on the Hudson River about 8.5 miles from LaGuardia Airport, New York City, after an almost complete loss of thrust in both engines following an encounter with a flock of birds." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-31T14:27:45.170" LastActivityDate="2015-10-31T14:27:45.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22564" PostTypeId="5" CreationDate="2015-10-31T14:29:39.053" Score="0" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-31T14:29:39.053" LastActivityDate="2015-10-31T14:29:39.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22565" PostTypeId="4" CreationDate="2015-10-31T14:29:39.053" Score="0" Body="TAM Airlines Flight 3054 was a scheduled passenger flight between Porto Alegre-São Paulo. On Tuesday, July 17, 2007, the Airbus A320-233 airliner overran the runway at São Paulo and crashed into a nearby TAM Express warehouse adjacent to a Shell filling station. It remains the deadliest aviation accident involving an A320." OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-10-31T14:29:39.053" LastActivityDate="2015-10-31T14:29:39.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22566" PostTypeId="2" ParentId="22556" CreationDate="2015-10-31T15:40:38.807" Score="7" Body="&lt;p&gt;In AF447 the falling motion most definitely affected the angle of attack. Due to the fact that the pf &lt;strong&gt;did&lt;/strong&gt; keep the stick pulled back for all but the last few seconds of the fall the aircraft was so steep that, although the aircraft was falling at a slight pitch up, angles of attack actually reached as high as 60°. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The descent was so steep that the air was passing over the pitot tubes at such an angle that it was reading below 40 knots, although the plane was moving far faster then that. The computer required that the airspeed be of a certain value to consider the aoa plausible so the stall warning stopped sounding even though the aoa was between 30° and 60° during the fall. When it hit the water the forward ground speed and the vertical speed were both 107 kts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as why the pilot did not realize he was stalled, that's the question of the century. Much effort has been put into figuring that out, and there are numerous things that are at play. But in the end I don't think anyone has come up with a satisfactory answer for that. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to dig into the causes of this crash and get a good understanding of Airbus systems in general I highly recommend &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B00E5W9YZG&quot;&gt;this book&lt;/a&gt; and it's companion &lt;a href=&quot;http://understandingaf447.com/&quot;&gt;website&lt;/a&gt;. The author is uniquely qualified and gives the most thorough explanation yet is not as technically challenging as reading the BEA report. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All of the numbers mentioned in this answer come from the linked book.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-10-31T15:40:38.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22567" PostTypeId="1" AcceptedAnswerId="22571" CreationDate="2015-10-31T16:11:10.427" Score="0" ViewCount="3281" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aL1hM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aL1hM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've recently learned of the Bell Boeing V-22 Osprey and it appears to be a very advanced and useful vehicle. I can instantly think of reasons why the Osprey would be successful such as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) It can take off in small places and land in small places unlike planes&lt;br&gt;&#xA;2) It can hover&lt;br&gt;&#xA;3) It can turn into a plane and fly fast&lt;br&gt;&#xA;4) It can pick up things like cars without the need to carry it inside like planes&lt;br&gt;&#xA;5) It can easily fly sideways and backwards&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my questions are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Why hasn't the Osprey advanced/been successful. For example how the F-15 went to the F-16 then the F-35 etc.&lt;br&gt;&#xA;2) What made Boeing choose to have rotors instead of the faster jet engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only possible reasons I can think of are things such as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Stealth/noise, the Osprey requires large rotors and probably makes double the noise as a helicopter or plane would make&lt;br&gt;&#xA;2) Maintenance costs, a helicopter requires more maintenance than a plane, I'd think the Osprey requires more maintenance than a helicopter or plane&lt;br&gt;&#xA;3) Cost, the Osprey probably costs more than an average plane or helicopter&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though I'm not sure of the real main reason as surely those reasons can be fixed.&lt;/p&gt;&#xA;" OwnerUserId="12062" LastActivityDate="2016-01-13T23:26:23.687" Title="Why was the Bell Boeing V-22 Osprey not worked on more?" Tags="&lt;military&gt;&lt;boeing&gt;" AnswerCount="4" CommentCount="8" ClosedDate="2016-01-13T21:17:30.963" ContentLicense="CC BY-SA 3.0" />
  <row Id="22568" PostTypeId="2" ParentId="22556" CreationDate="2015-10-31T17:25:57.373" Score="6" Body="&lt;p&gt;Your understanding of the situation is correct: The angle of attack was beyond stall and the aircraft was in a descent which reduces the pitch attitude, so the resulting acceleration felt to the pilots close to that in normal flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it is important to understand that the aircraft produced lift equivalent to its weight. It was in a steady state - if lift had been too small, it would had accelerated downwards. Let's calculate how big the descent angle could have been: The minimum speed of an A330 in clean configuration is &lt;a href=&quot;http://www.deltava.org/library/dva_a330%20manual.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;166 KIAS at the maximum landing weight&lt;/a&gt;, which is 396,800 lbs or 182 t. Since the aircraft had just flown for less than four hours, I would estimate that it weighed 205 t at the time of the accident, which makes its stall speed 176 KIAS or 90.6 m/s. In about 3½ minutes it went from 11,600 m to sea level, which gives us an average sink speed of 55 m/s. For a very rough estimate we use the mean between the stall speed at 11,600 m, which is 175 m/s, and the stall speed at sea level: 132 m/s. The resulting angle is 22.5° (note that the flight speed is along the flight path, so you need the arctan of 55 / 132.6). The real value was probably a little lower since the aircraft flew a little faster than its stall speed to compensate for the lower lift coefficient in the stalled state. Modern supercritical airfoils have a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21035/does-stall-angle-of-attack-in-inverted-flight-change-due-to-the-camber-of-an-asy/21041#21041&quot;&gt;very benign stall behavior&lt;/a&gt;, and I would estimate that the speed was not much above stall speed. Also, it did not fly constantly at the same attitude, but the copilot released his pitch-up command twice, only to resume it seconds later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I use the cited values at the time of impact (107 kts ground speed and 108 kts sink speed), the airspeed is 78.2 m/s. Assuming standard atmospheric conditions, this gives a lift coefficient of 1.48 - way more than any stalled wing can manage. This can only be explained by a strong headwind, of which there is no word in the Wikipedia article. Since the plane was flying through a storm, strong winds should be expected, and then the figures become credible again. Tom's value of 60° sounds very unlikely to me - at that angle the wing produces mostly drag and the aerodynamic forces act at mid chord, producing a strong pitch-down moment which cannot be compensated by a tail surface at those 60°, regardless of elevator position. Around 20° to 30° angle of attack the whole situation becomes much more plausible.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT: Now I spent some time reading the BEA report (thank you @mins for the link!) and are deeply troubled by some details. In FL360 (&lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/imageshr/figure.65.en.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;figure 65&lt;/a&gt;) and with 1g (&lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/imageshr/figure.66.en.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;figure 66&lt;/a&gt;), the airplane was supposed to have flown at only Mach 0.4. This translates into a post-stall lift coefficient of 2.09, which is physically impossible. Some lift is contributed by the engines due to the positive pitch angle, granted, but by far not enough to make this low speed possible. At least BEA agrees with my mass estimate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dynamic pressure at this point is only 2660 N/mm², and in clean configuration this is too little to prevent the plane from dropping like a stone at any angle of attack. The same goes for the condition right before it impacted the ocean surface: 78.2 m/s is too low; at least 95 m/s would be needed for a barely credible post-stall lift coefficient of 1.0. If I add 17 m/s wind speed, things get back into normal territory. Unfortunately, the only wind information in the plots is in &lt;a href=&quot;http://www.bea.aero/fr/enquetes/vol.af.447/imageshr/figure.64.en.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;figure 64&lt;/a&gt;, when the stall begins. Headwind is around 0, but crosswind is between 20 and 30 m/s. If the airplane had sideslipped so badly during the stall, it would had entered a spin. It just does not make sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the text we get a headwind information at the time of the autopilot disconnect (page 91):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Prior to the disconnection of the autopilot, a constant headwind&#xA;  component of 15 kt had to be added in order to make the simulation’s&#xA;  ground speed match the recorded parameter. This value was consistent&#xA;  with the wind parameters recorded.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the most important line is at the start of the analysis, hidden away at the bottom of page 90. It should be bold and underlined, but isn't:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The validity of the model is limited to the known flight envelope&#xA;  based on flight tests.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airbus did some more flights at the same configuration and loading as AF447 had at the time of the accident, but it appears that buffet limited their flown angles of attack to below 10°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It must be concluded that all angle of attack values exceeding 10° are purely speculative and not backed by flight test data.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-11-12T19:52:36.577" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22569" PostTypeId="5" CreationDate="2015-10-31T17:26:21.683" Score="0" Body="&lt;p&gt;The accident took place in 2009 and has raised questions about Airbus's flight control designs, how flight computers should present failures and warnings to the crew, and crew training for unusual situations.&#xA;For a full description of the accident, read about it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;at BEA: &lt;a href=&quot;http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php&quot; rel=&quot;nofollow&quot;&gt;Final report&lt;/a&gt;,&lt;/li&gt;&#xA;&lt;li&gt;on &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; or&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://avherald.com/h?article=41a81ef1/0068&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;the Aviation Herald&lt;/a&gt;.&#xA;both of which link to the BEA's official investigation reports.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Related tags:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/airbus-330&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus-330&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus-330&lt;/a&gt;, &lt;a href=&quot;/questions/tagged/airbus&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airbus&amp;#39;&quot; rel=&quot;tag&quot;&gt;airbus&lt;/a&gt; (the aircraft that crashed was an Airbus 332)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/stall&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;stall&amp;#39;&quot; rel=&quot;tag&quot;&gt;stall&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/safety&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;safety&amp;#39;&quot; rel=&quot;tag&quot;&gt;safety&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/accidents&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;accidents&amp;#39;&quot; rel=&quot;tag&quot;&gt;accidents&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/accident-investigation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;accident-investigation&amp;#39;&quot; rel=&quot;tag&quot;&gt;accident-investigation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="998" LastEditorUserId="2324" LastEditDate="2015-11-11T18:12:36.807" LastActivityDate="2015-11-11T18:12:36.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22570" PostTypeId="4" CreationDate="2015-10-31T17:26:21.683" Score="0" Body="Air France flight 447 crashed into the Atlantic Ocean in mid-2009 after entering a stall from which the flight crew failed to recover." OwnerUserId="998" LastEditorUserId="753" LastEditDate="2018-04-15T12:03:30.430" LastActivityDate="2018-04-15T12:03:30.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22571" PostTypeId="2" ParentId="22567" CreationDate="2015-10-31T17:58:00.773" Score="5" Body="&lt;p&gt;&lt;em&gt;Why was the Bell Boeing V-22 Osprey not worked on more?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Osprey idea is an old one and it never worked well. For example, I have found a patent form 1921 (see the picture) for a flying machine that has some common points with the Osprey. Large diameter propellers are not efficient for planes and small rotors are not suitable for helicopters. A hybrid, like Osprey, has the advantage of not needing a runway to land or take off but at the same time, once in the air, it has to pay the price of using two inefficient propellers for flying hundreds of kilometers. Also, if it is used more as a helicopter the rotors are not as efficient as the ones of a true helicopter.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mdXXY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mdXXY.jpg&quot; alt=&quot;Traian Vuia Helicopter&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://bases-brevets.inpi.fr/en/document-en/FR516838/publications.html?p=5&amp;amp;s=1446310790272&amp;amp;cHash=a57bd9ef6e02c0a88e6648b521565907&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flying machine&lt;/a&gt;, authour &lt;a href=&quot;https://en.wikipedia.org/wiki/Traian_Vuia&quot; rel=&quot;nofollow noreferrer&quot;&gt;Traian Vuia&lt;/a&gt;, April 1921.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/spvNO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/spvNO.jpg&quot; alt=&quot;Boeing V-22 Osprey&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;Bell Boeing V-22 Osprey&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="938" LastEditDate="2015-11-01T23:15:02.470" LastActivityDate="2015-11-01T23:15:02.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22572" PostTypeId="1" AcceptedAnswerId="22575" CreationDate="2015-10-31T18:10:34.420" Score="18" ViewCount="2042" Body="&lt;p&gt;The &quot;&lt;a href=&quot;https://aviation.stackexchange.com/a/22497/11671&quot;&gt;dead-man's curve&lt;/a&gt;&quot; in a typical helicopter height/velocity (H/V) diagram is commonly referenced to indicate that &quot;towering flight&quot; is dangerous and avoided in general practice.  (Simon explained, &quot;The &lt;em&gt;Avoid&lt;/em&gt; curve [outlines] the combinations of height and speed in which test pilots (i.e., the best) have demonstrated that a safe landing is possible if the engine quits.&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But H/V diagrams also have second envelope that is marked for avoidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q4QB4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q4QB4.jpg&quot; alt=&quot;Height/Velocity Diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if this area in the lower right has an ominous name: If not perhaps we should call it the &quot;dead-man's plateau?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why is it considered unsafe to fly at extremely low altitudes at indicated airpseeds above about 50 knots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a comment on this in the answer above Simon says, &quot;At that speed, if the engine quits, the nose will pitch down and you will be on the ground, with no control and high speed, before you know what's happened.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone elaborate on the dynamics of this?  Why would the nose pitch down abruptly if the engine quits?  If that's such a reliable effect would it not be trivial and worthwhile to have a torque-driven spring that bears on the cyclic, so if torque suddenly changes then the cyclic is just as suddenly nudged backwards?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, one is left wondering if the full answer isn't more nuanced: The most striking characteristic of the dead-man's plateau is that it appears to be the height at which one enters ground effect.  Is there some other aerodynamic phenomenon at play in high-speed ground effect flight?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-11-21T22:32:05.157" Title="Why is there a plateau in helicopter H/V diagrams?" Tags="&lt;safety&gt;&lt;helicopter&gt;&lt;ground-effect&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22573" PostTypeId="2" ParentId="22567" CreationDate="2015-10-31T19:00:55.737" Score="8" Body="&lt;p&gt;The Osprey has arguably been quite successful considering the circumstances. As Energizer777 points out, the basic idea is not new, and there were many engineering challenges to create a viable aircraft. That these challenges were solved and the plane is now in production and active service seems to be a pretty big success. Also, this has all happened relatively recently. The V-22 first flew in 1989 while the F-15 and F-16 both date back to the early 1970's (and are still in active service). The challenges in refining the design pushed introduction of the V-22 out until 2007. The design just hasn't had enough time to mature past the first successful application. You might consider the civilian tilt-rotor &lt;a href=&quot;https://en.wikipedia.org/wiki/AgustaWestland_AW609&quot;&gt;AW609&lt;/a&gt;, currently targeted for certification in 2017, as the next advancement of the design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Props/rotors are more efficient than a jet engine at low speeds. Given that the slow and vertical portions of the flight are very important to the design, this decision makes sense. The prop wash also flows over the wing, allowing the wing to be more effective with a short span. Using turboshaft engines rather than jets also allows one engine to drive both rotors if the other engine fails, making single engine operation easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right about the drawbacks of the design. The V-22 is noisy and not as agile has a helicopter in slow flight. Maintenance requirements are high and were certainly an issue early on in the introduction to service. And upfront costs are also more than a helicopter or airplane of comparable size. However, the capabilities you listed first are worth these added costs, at least to those that have purchased/ordered the V-22.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-10-31T19:00:55.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22574" PostTypeId="1" CreationDate="2015-10-31T19:18:08.943" Score="2" ViewCount="2027" Body="&lt;p&gt;What is a straight wing? I need this for my science project. I have looked for other answers on this website, but I cannot find any. Please help!&lt;/p&gt;&#xA;" OwnerUserId="12069" LastActivityDate="2015-10-31T20:39:37.490" Title="What is a straight wing on an airplane?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-10-31T21:06:01.157" ContentLicense="CC BY-SA 3.0" />
  <row Id="22575" PostTypeId="2" ParentId="22572" CreationDate="2015-10-31T19:21:57.050" Score="23" Body="&lt;p&gt;As speed increases, most helicopters pitch up.  This is because the lift generated on the side of the retreating blade gets progressively less than the lift generated on the advancing blade side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to &lt;a href=&quot;https://en.wikipedia.org/wiki/Precession&quot; rel=&quot;noreferrer&quot;&gt;precession&lt;/a&gt;, the effect of this is felt 90 degrees later so instead of rolling to the left (or right, depending on which way the blades rotate) because of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dissymmetry_of_lift&quot; rel=&quot;noreferrer&quot;&gt;dissymmetry of lift&lt;/a&gt;, the tail drops, therefore pitching the nose up.  Whether this happens on a particular helicopter, and by how much, depends largely on the pitch stabilisers.  However, helicopters are naturally unstable in pitch.  You cannot take your hand of the  cyclic and maintain a constant attitude, absent any autopilot or other automatic assistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the helicopter accelerates, the pilot subconciously counteracts this by applying foward cyclic pressure.  The higher the speed, the more forward pressure is needed to maintain altitude and the helicopter flies nose down.  You fly a helicopter by &quot;sight picture&quot; to such an extent, that to accelerate, you pitch the nose down to give you the &quot;65 kt picture&quot;, or the &quot;100 kt picture&quot;, allow the aircraft to accelerate to the desired speed, then trim.  The nose is pitched down a lot at 100 kts compared to say 50.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the engine quits, assuming it's an instantaneous failure, there is nothing to stop that forward pressure forcing the nose down and at such low heights and high speed, losing 18 feet of height before the pilot reacts and pulls back to flare would be easy.  Even if they react really quickly and flare without losing much more than 5 or 10 feet, there is a very real risk that the tail will strike the ground and at those high speeds, that will result in a really bad crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume that everything goes right. There is no time at that height to lower the collective and raise it again.  You will also have a lot less than a second to flare so will lose very little forward speed.  In the best case, you are going to land at 50 kts or higher with the collective in your armpit and the rotors already stalled, if not stopped altogether, and this is at best a bad crash, quite possibly fatal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important thing to remember is that the shaded areas represent the flight regimes where test pilots, with instant reactions since they initiate the manoeuvre, cannot demonstrate a safe landing with no damage.  This is at the edges of the shaded areas and once they get to the point of saying &quot;one more foot, and we would not have had a successful landing&quot;, they stop exploring the envelope and draw the curve in the POH.  To add a safety margin, the tests are done at max weight.  Even so, the wise pilot will give those areas a wide berth whenever possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why isn't there some automatic device to pull the cyclic back?  Because you do not do this if the engine quits when in a hover or up to about 10 kts at low height.  In the avoid area you ask about, it would need to pull, then push to level the skids again in the blink of an eye.  It's different when hovering at 1,000 ft and different again if doing 90 kts at 1,000 ft. And that's before we add all the variables - pressure altitude, temperature, wind strength and direction.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To deal with all of this, you would need a very clever system loaded with sensors.  Most people call such systems &quot;pilots&quot;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would rather just avoid the shaded areas.  It's no big deal.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="3504" LastEditDate="2015-11-21T22:32:05.157" LastActivityDate="2015-11-21T22:32:05.157" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="22577" PostTypeId="2" ParentId="22574" CreationDate="2015-10-31T19:48:10.447" Score="4" Body="&lt;p&gt;&lt;em&gt;What is a straight wing on an airplane?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A straight wing is a wing that is not swept (see the images).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MnfMk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MnfMk.png&quot; alt=&quot;Straight and swept wimgs&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://paperaeroplanes.com/blog/?p=73&quot; rel=&quot;nofollow noreferrer&quot;&gt;Straight and swept wings&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QYqQC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QYqQC.jpg&quot; alt=&quot;The unswept wings&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Swept_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Unswept, straight wings&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VapvQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VapvQ.jpg&quot; alt=&quot;Swept wings&quot;&gt;&lt;/a&gt; &#xA;&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Swept_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Swept wings&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2015-10-31T20:39:37.490" LastActivityDate="2015-10-31T20:39:37.490" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22578" PostTypeId="1" AcceptedAnswerId="22579" CreationDate="2015-10-31T21:18:36.317" Score="4" ViewCount="360" Body="&lt;p&gt;I saw this beacon at an old airport; how and in what situations was it used?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fP6VG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fP6VG.png&quot; alt=&quot;Beacon at Ljunbyhed, ESTL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9690" LastEditorUserId="7532" LastEditDate="2015-11-01T00:47:55.583" LastActivityDate="2015-11-01T00:47:55.583" Title="How was this old beacon used?" Tags="&lt;navigation&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22579" PostTypeId="2" ParentId="22578" CreationDate="2015-10-31T21:24:08.890" Score="6" Body="&lt;p&gt;It's the &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerodrome_beacon&quot;&gt;airfield identification beacon&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aerodrome beacon or rotating beacon is a beacon installed at an&#xA;  airport or aerodrome to indicate its location to aircraft pilots at&#xA;  night.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An aerodrome beacon is mounted on top of a towering structure, often a&#xA;  control tower, above other buildings of the airport. It produces&#xA;  flashes not unlike that of a lighthouse.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Airport and heliport beacons are designed in such a way to make them&#xA;  most effective from one to ten degrees above the horizon; however,&#xA;  they can be seen well above and below this peak spread. The beacon may&#xA;  be an omnidirectional flashing xenon strobe, or it may be an&#xA;  aerobeacon rotating at a constant speed which produces the visual&#xA;  effect of flashes at regular intervals. Flashes may be of just a&#xA;  single color, or of two alternating colors.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-10-31T21:24:08.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22581" PostTypeId="1" AcceptedAnswerId="22582" CreationDate="2015-11-01T02:50:01.417" Score="17" ViewCount="3071" Body="&lt;p&gt;In &lt;a href=&quot;https://www.youtube.com/watch?v=uccxL_TptOg&quot;&gt;this YouTube video of a takeoff and landing in a Dash-8&lt;/a&gt;, you can see the pilot, while landing, keeps his right hand on the throttle levers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The co-pilot keeps his left hand at the base of the throttle levers during this time. This happens at 3:38 in the video. I assume this is to ensure both pilot and co-pilot agree when lowering the throttle? I'm just guessing, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this, and are there other similar events that happen during a flight?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="23223" LastEditDate="2019-06-08T17:16:08.793" LastActivityDate="2019-12-10T03:40:56.993" Title="Why does the co-pilot sometimes keep a hand on the throttle as well as the pilot?" Tags="&lt;landing&gt;&lt;airline-operations&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22582" PostTypeId="2" ParentId="22581" CreationDate="2015-11-01T03:52:20.750" Score="16" Body="&lt;p&gt;The pilots were probably executing a Cat II coupled or monitored approach. The PF is flying the plane (via autopilot, usually), while the PNF had his hands at the base of the throttle ready to take over to initiate a manual go around (or land in some cases, this varies from airline to airline).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/339153/&quot;&gt;thread regarding this on this on airliners.net&lt;/a&gt;. It gives one version of the procedure:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At my airline we use this procedure for Cat II approaches. The FO always flies the approach... well the autopilot flies it and the FO monitors the instruments, ready to perform a missed approach if the approach becomes unstable. The Captain at the 500 to minimums call places their hand near the base of the thrust levers, under the FOs arm, and focuses outside looking for the runway. If at any point prior to minimums the captain gets the runway in sight, they call &quot;landing, my controls&quot; and move their hand up to the thrust levers, bumping the FOs arm and hand up and off of the thrust levers. If at minimums and the runway is not in sight the FO performs the missed approach. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-01T03:52:20.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22583" PostTypeId="1" AcceptedAnswerId="22587" CreationDate="2015-11-01T08:03:12.273" Score="1" ViewCount="381" Body="&lt;p&gt;I watched a flight mechanics lecture that mentioned that some combat aircraft like the Hornet has a 'mode' where the on-board computer simultaneously and automatically adjusts all the control surfaces to make the plane fly with &lt;strong&gt;Statically neutral stability&lt;/strong&gt; which to my understanding means that the lift moment is constantly aligned with the plane's center of gravity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The result is that the pilot is able to pull back on the controls and pitch up and release the input and have the plane continue to fly in a new direction without any tendency to diverge or return to equilibrium (the trim position).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true and is this stability only possible with a constant re-balance of the control surfaces of the plane?&lt;/p&gt;&#xA;" OwnerUserId="12056" LastEditorUserId="19" LastEditDate="2017-03-03T08:23:05.783" LastActivityDate="2021-05-17T23:41:44.543" Title="Can 'neutral static stability' only be achieved by constantly augmenting the control surfaces?" Tags="&lt;flight-controls&gt;&lt;fixed-wing&gt;&lt;stability&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22584" PostTypeId="2" ParentId="15581" CreationDate="2015-11-01T09:03:39.267" Score="3" Body="&lt;p&gt;The previous answers detail the air traffic controller types and their roles very well. However, I find this diagram quite helpful to visually recall the airspace divisions.&lt;a href=&quot;https://i.stack.imgur.com/VdR6x.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VdR6x.png&quot; alt=&quot;Airspace Organisation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACC: Area Control Center&lt;/p&gt;&#xA;&#xA;&lt;p&gt;APP: Approach/Departure Control&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TWR: Tower&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UTA: Upper Control Area&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CTA: Control Area&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TMA: Terminal Control Area&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CTR: Control Zone&lt;/p&gt;&#xA;" OwnerUserId="96" LastActivityDate="2015-11-01T09:03:39.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22585" PostTypeId="1" AcceptedAnswerId="22586" CreationDate="2015-11-01T09:31:25.810" Score="3" ViewCount="1305" Body="&lt;p&gt;In a previous question someone asked &lt;a href=&quot;https://aviation.stackexchange.com/questions/21987/why-is-the-maximum-speed-of-current-fighter-aircraft-lower-than-those-from-the-1&quot;&gt;why do modern fighter jet speeds decrease compared to older fighter jets&lt;/a&gt;, and someone hinted that nowadays top speed is not a factor considering modern rockets which will anyway exceed the maximum G forces that a human body can withstand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, in the F-22 vs T-50 comparisons many hint at superior maneuverability and top speeds of the Russian T-50 design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shouldn't modern fighter jets be all about BVR (beyond visual range) capabilities and thus speeds and maneuverability be &quot;surpassed&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine modern fighter jets to be basically bricks in the air with a lot of high tech long distance warfare technology.&lt;/p&gt;&#xA;" OwnerUserId="12074" LastEditorUserId="1467" LastEditDate="2018-01-22T13:02:10.983" LastActivityDate="2018-01-22T13:02:10.983" Title="Why maneuverability and top speed are still issues in 5th generation air superiority fighter jets" Tags="&lt;fighter&gt;&lt;maneuverability&gt;" AnswerCount="3" CommentCount="3" ClosedDate="2015-11-02T07:50:39.410" ContentLicense="CC BY-SA 3.0" />
  <row Id="22586" PostTypeId="2" ParentId="22585" CreationDate="2015-11-01T14:20:25.323" Score="8" Body="&lt;p&gt;Fighter jets are not bricks with powerful radar and long range missiles. BVR combat is an extremely complex affair conceptually, operationally and technologically. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For BVR combat to be initiated, the enemy aircraft should first be identified and sorted as a threat. However, assuming that both have similar radars, the inverse square law ($S \ \propto \ \frac{1}{R^{2}}$) means that you are exposing yourself to the enemy before identifying him. Combat between two stealth aircraft (F-22 vs T-50) is not unlike two men with a gun and flashlight in a dark room, as someone noted. The first one to switch on the radar is actually at a &lt;em&gt;disadvantage&lt;/em&gt; and against a highly trained enemy, possibly suicidal. Also, let's not forget SAM ARM missiles that can home on the aircraft radars.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Though the number of aircraft shot down by radar guided missiles (as opposed to IR missiles, which are usually fired WVR) have risen significantly both in numbers and also as a percentage (of total aircraft shot down), the probability of achieving a kill by a BVR missile is still uncomfortably low. For example, the following table shows the ratio of 'kills' by radar guided missiles post WWII.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2ttAc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2ttAc.png&quot; alt=&quot;BVR Kills&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Table from &lt;em&gt;Promise and Reality: Beyond Visual Range (BVR) Air-To-Air Combat&lt;/em&gt; by Lt Col Patrick Higby, USAF&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The high percentage of BVR kills in Gulf war is basically due to two factors- AWACS and IFF(Non-Cooperative Target Recognition (NCTR) system), which gave sufficient confidence to permit BVR shots. It is highly unlikely that such a superiority level and confidence is available in case of war between two peers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another thing is that barely any of the BVR shots are fired head on due to the high closing speeds. So in all probability, you have to maneuver yourself in a position where a tail (or an above) shot is possible. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, if some missile is fired at you, speed and maneuverability are critical to carry out evasive maneuvers. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Most of the combat aircraft use in present day has nothing to do about air superiority. They are mostly used as precision guided bomb trucks. Optimizing fighters for BVR combat sacrificing other parameters is, at the least, foolhardy.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So far, the most important contributors to BVR victories (in Gulf War, for example) are not due to some inherently superior technology, but due to human factors- pilot skill and opponent's weakness. It is potentially catastrophic to generalize the doctrine against a near-peer opponent.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-01T14:20:25.323" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22587" PostTypeId="2" ParentId="22583" CreationDate="2015-11-01T15:06:13.967" Score="1" Body="&lt;p&gt;First, definitions- The &lt;a href=&quot;https://aviation.stackexchange.com/questions/164/what-does-the-term-trimming-most-commonly-mean-in-aviation?rq=1&quot;&gt;purpose of trimming&lt;/a&gt; to to free the pilot from having to exert a constant pressure on the controls i.e., when the aircraft has been trimmed, there is no need for the pilot (or autopilot) to give any control input (for a set of conditions like level flight or climb).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft which is (statically) neutrally stable tends to stay in its new attitude when it's disturbed. For example, if you pitch the nose up by, say $2^{\circ}$, and then immediately after that it stays at $2^{\circ}$ nose up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen from above, you need not balance the control surfaces continuously while the aircraft has been trimmed. Stability has to do with the aircraft attitude and not control surface movement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft (like F/A-18 Hornet) require constant operation of flight control surfaces (by computer) because they have relaxed static stability- they will oscillate and diverge from an attitude if left to themselves.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-11-01T15:06:13.967" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22589" PostTypeId="1" CreationDate="2015-11-01T16:19:01.723" Score="9" ViewCount="6247" Body="&lt;p&gt;The Messerschmitt Bf-109 had struts holding the stabilizer in place up and including the E version. I marked it with a red circle in the picture below of the 109 E-3 of the Flying Heritage Collection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wStdA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wStdA.png&quot; alt=&quot;Bf-109 E-3 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bf-109 E-3 in flight (picture &lt;a href=&quot;http://flyingheritage.com/TemplatePlane.aspx?contentId=19&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that Willy Messerschmitt was fanatical about reducing drag, and contemporaries like the Hawker Hurricane, the Supermarine Spitfire, the Curtiss P-40, the Heinkel 112 or the Dewoitine 520 had cantilevered stabilizers, why would he tolerate a strut on the tail of his new fighter aircraft?&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1467" LastEditDate="2017-02-08T14:43:00.630" LastActivityDate="2017-02-08T14:43:00.630" Title="Why did the early versions of the Me-109 use a braced stabilizer?" Tags="&lt;aircraft-design&gt;&lt;aviation-history&gt;&lt;fighter&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22590" PostTypeId="1" AcceptedAnswerId="22592" CreationDate="2015-11-01T17:41:18.493" Score="9" ViewCount="16865" Body="&lt;p&gt;So many people use these words interchangeably, but after a little searching on Google, I found they are not quite the same thing. All the links I read explain things in a misleading way which pushed my confusion even further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for a simple explanation on the effect of these parts on &lt;em&gt;The Four Forces of Flight&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="19" LastEditDate="2016-07-11T15:27:40.617" LastActivityDate="2016-07-11T17:34:12.707" Title="What are the differences between air brakes, spoilers and lift dumpers?" Tags="&lt;terminology&gt;&lt;lift&gt;&lt;drag&gt;&lt;spoilers&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22591" PostTypeId="1" AcceptedAnswerId="22601" CreationDate="2015-11-01T17:53:36.353" Score="18" ViewCount="4534" Body="&lt;p&gt;The chances of a commercial flight crash are about 1 in 1,200,000 - pretty low. If &lt;a href=&quot;https://aviation.stackexchange.com/questions/2263/what-is-the-lifespan-of-commercial-airframes-in-general/2264#2264&quot;&gt;each plane makes about 40,000 flights&lt;/a&gt; in it's lifetime, about 1 in 30 airplanes will be involved in a crash before it reaches retirement.&lt;/p&gt;&#xA;&lt;p&gt;Is this an accurate estimate? 1 in 30 seems like quite a large amount of airplanes to crash before they are retired.&lt;/p&gt;&#xA;&lt;p&gt;I'm also assuming here that after a crash an airplane is written off. This may not be the case - I don't know how much a plane can be repaired.&lt;/p&gt;&#xA;" OwnerUserId="4357" LastEditorUserId="4357" LastEditDate="2021-02-06T17:57:42.127" LastActivityDate="2021-04-30T15:45:25.070" Title="What percentage of airplanes are involved in a crash in their lifetime?" Tags="&lt;safety&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="22592" PostTypeId="2" ParentId="22590" CreationDate="2015-11-01T17:57:01.010" Score="9" Body="&lt;p&gt;Air brakes increase drag with little change in lift. The following image shows the air brake being used in BAe 146&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TLp9F.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TLp9F.jpg&quot; alt=&quot;BAe 146 Air Brake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Eurowings_bae146-300_d-aewb_arp.jpg#/media/File:Eurowings_bae146-300_d-aewb_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;Eurowings bae146-300 d-aewb arp&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;noreferrer&quot; title=&quot;User:Arpingstone&quot;&gt;Adrian Pingstone&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoilers both increase drag and reduce lift- basically, they change the lift-to-drag ratio. Sometimes, they are also used as control surfaces in lieu of ailerons. This image shows a Boeing 777 spoilers being used in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KTLtA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KTLtA.jpg&quot; alt=&quot;777 Spoilers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Screengrab from &lt;a href=&quot;https://www.youtube.com/watch?v=kzENu889X34&quot; rel=&quot;noreferrer&quot;&gt;youtube.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift dumpers are basically ground spoilers that are used to 'dump' lift, especially immediately after landing, where you want rapid reduction in lift. The following image shows lift dumpers being used in BAe 146.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rRTfk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rRTfk.jpg&quot; alt=&quot;BAe 146 landing spoilers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-01T18:24:42.560" LastActivityDate="2015-11-01T18:24:42.560" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22593" PostTypeId="1" CreationDate="2015-11-01T18:13:55.107" Score="36" ViewCount="37847" Body="&lt;p&gt;Why do police helicopters always fly in circles while news helicopter hover in one spot? Is it to avoid criminals opening fire at them, or is it because there is a difference between the two types of helicopters?&lt;/p&gt;&#xA;" OwnerUserId="12079" LastActivityDate="2017-12-21T03:34:40.303" Title="Why do police helicopters always fly in circles?" Tags="&lt;helicopter&gt;" AnswerCount="4" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22595" PostTypeId="2" ParentId="22589" CreationDate="2015-11-01T18:19:10.793" Score="8" Body="&lt;p&gt;The design was carried over from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_108&quot; rel=&quot;noreferrer&quot;&gt;Bf 108&lt;/a&gt;. This would've enabled a lighter structure. The ME-109 versions 'B' through 'E' had them, which was finally removed from the 'F' version. It came back in the 'H' version, which was cancelled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the struts were removed in 'F' version, it was found that high-frequency oscillation in the tailplane spar was overlapped by harmonic vibrations from the engine, resulting in failure; this required stiffening of the structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be fair, the Hurricane prototype had struts too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WutiT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WutiT.jpg&quot; alt=&quot;Hurricane Prototype&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: network54.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2015-11-01T23:30:06.533" LastActivityDate="2015-11-01T23:30:06.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22596" PostTypeId="2" ParentId="22591" CreationDate="2015-11-01T18:26:53.583" Score="11" Body="&lt;p&gt;In case nobody can find official figures, let's try to make a rough estimate:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;From the data in the &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Air_Transport_Association&quot; rel=&quot;noreferrer&quot;&gt;IATA&lt;/a&gt; study cited in the question &lt;a href=&quot;https://aviation.stackexchange.com/questions/21593/what-are-the-statistical-probabilities-of-commercial-aircraft-accidents/21595#21595&quot;&gt;What are the statistical probabilities of commercial aircraft accidents?&lt;/a&gt;, we know for year 2014 there was:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;100.000 flights per day,&lt;/li&gt;&#xA;&lt;li&gt;A total of 12 accidents with casualties,&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;According to &lt;a href=&quot;http://avolon.aero/wp/wp-content/uploads/2014/09/WFF_2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;this study&lt;/a&gt;, there were about 23.000 aircraft in service in 2014,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Let's assume a mean 30 years aircraft lifespan&lt;/em&gt; for the aircraft in service in 2014,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Mean flights per day per aircraft = 4.3,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;360 fatal accidents during a period equivalent to an aircraft lifespan.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's a rate of 1.56 % aircraft with a fatal accident, or &lt;strong&gt;1 / 64&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this time:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft involved in the accident will have flown 47,000 times,&lt;/li&gt;&#xA;&lt;li&gt;The 64 aircraft will have totaled 3 millions flights.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Said otherwise: an significant airline with 320 (5 × 64) aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Will face a disaster every 6 years,&lt;/li&gt;&#xA;&lt;li&gt;After 3 millions flights (based on 2014 statistics).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(updated with a worldwide fleet of 23.000 aircrafts instead of 44.000 initially estimated.)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-11-02T10:17:24.480" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22597" PostTypeId="2" ParentId="1181" CreationDate="2015-11-01T18:35:55.000" Score="1" Body="&lt;p&gt;Several traditions have developed in the USA around &quot;soloing&quot;, including drenching the student with water and cutting off and permanently displaying the back of his or her shirt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In American aviation lore, the traditional removal of a new pilot's shirt tail is a sign of the instructor's new confidence in his student after successful completion of the first solo flight. In the days of tandem trainers, the student sat in the front seat, with the instructor behind. As there were often no radios in these early days of aviation, the instructor would tug on the student pilot's shirttail to get his attention, and then yell in his ear. A successful first solo flight is an indication that the student can fly without the instructor (&quot;instructor-less&quot; flight). Hence, there is no longer a need for the shirt tail, and it is cut off by the (often) proud instructor, and sometimes displayed as a trophy.&lt;/p&gt;&#xA;" OwnerUserId="12080" LastActivityDate="2015-11-01T18:35:55.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22598" PostTypeId="2" ParentId="22593" CreationDate="2015-11-01T18:46:47.913" Score="33" Body="&lt;p&gt;There is little difference between the helicopters used by news crews and police. It is their operation that differs. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Flying instead of hovering helps minimize the chance of getting shot. There has been incidents when &lt;a href=&quot;https://web.archive.org/web/20170106090125/https://www.theguardian.com/world/2009/oct/17/rio-favela-violence-helicopter&quot; rel=&quot;noreferrer&quot;&gt;law enforcement helicopters have been shot down&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Forward flight (at low speed) uses less power compared to hover. This reduces the engine load and increases the time spent over target.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Police helicopters fly pretty low compared to the news helicopters. Hovering for long periods can result in one settling in their own downwash. In this case, the altitude can help news helicopters to gain forward momentum to get out of this. As this option is not available to police helicopters, it is better for them to fly in circles. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="19029" LastEditDate="2017-07-06T15:42:49.213" LastActivityDate="2017-07-06T15:42:49.213" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22599" PostTypeId="2" ParentId="22593" CreationDate="2015-11-01T18:52:44.777" Score="73" Body="&lt;p&gt;Police helicopters &lt;strong&gt;don't always&lt;/strong&gt; fly in circles. I've often seen my local police helicopter hovering. There are a few reasons you might have seen police helicopters flying in circles:-&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Not all types of helicopter can hover out of ground effect. It might be that the police helicopters in your area can't hover at the heights they work at, with the weight of their usual equipment.&lt;/li&gt;&#xA;&lt;li&gt;Helicopters are safer if they're moving forwards than hovering. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2248/what-happens-when-a-helicopter-loses-an-engine&quot;&gt;In the event of an engine failure, they can autorotate to land safely&lt;/a&gt;, but they need to have some airspeed to be able to do this. The required airspeed depends on height (see the chart in the linked question), so if your news helicopters are usually operated higher up than police helicopters, they may be able to hover safely. (This is quite likely, as police aircraft are exempt from the 500 ft rule and the 1000 ft rule, while news helicopters are not.)&lt;/li&gt;&#xA;&lt;li&gt;Police helicopters often circle to search an area for a fugitive or casualty using thermal imaging cameras. News helicopters tend to either follow a vehicle or hover to get a steady camera shot of a news event.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="998" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-11-01T18:52:44.777" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22600" PostTypeId="2" ParentId="3548" CreationDate="2015-11-01T19:08:12.450" Score="1" Body="&lt;p&gt;It is my understanding that the issue isn't whether the pilot receives compensation, or anyone else, such as the owner of the plane or the person selling the hamburger.  The issue is that the &quot;passenger is paying something&quot;, or giving up something of value, to be in the flight; AND when a passenger is paying for a flight, in the eyes of the FAA, they are due a greater amount of safety guarantee by the FAA.  This is why there is now a min flight hours (500) of a private pilot to fly these flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We always tend to think of compensation backwards, as from the pilots perspective.  And we do that because we, the pilots, want to know if &quot;we&quot; are Ok when we carry passengers.  But really the FAA is concerned not so much about us, but for the passengers; and see their (the FAA's) responsibilities toward them, their safety, and their expectations when they have extended value (money, gifts, even good will) for a flight, even if it is just a joy ride or site-seeing trip, or trip to get a hamburger (which is really a trip to go flying of course).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just imagine a situation, which would likely happen a lot if the FARs allowed, where a freshly minted pilot, with say only 90 hours TT, and all the eagerness in the world to exercise and demonstrate his/her new privilege to everyone who was willing, offered to fly charity flights for his/her church.  Now immagine the likely expectations and assumptions of those that &quot;made a donation&quot; to the church (read paid for) to get a flight.  These people aren't expected to know anything about aviation, pilot certification, annuals, 100 hr checks, or even what makes a plane fly in the first place.  Do you think they are expecting their flight to be piloted by a freshly minted, still scared to stall the plane, pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at it this way makes the FAA's perspective a bit more clear in my mind.  We should always feel a lot more responsible when we are carrying passengers, those that are the sons and daughters, mothers and fathers, friends and loved ones of others.  And we should recognize and honor their expectations when they entrust their lives to fly with us.  We should also understand that if they are unwitting, and in some sense paying passengers of ours, that maybe don't know us and our skills from that of an axe murder, that they likely have at least the expectation that the FAA has their back. &lt;/p&gt;&#xA;" OwnerUserId="12082" LastActivityDate="2015-11-01T19:08:12.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22601" PostTypeId="2" ParentId="22591" CreationDate="2015-11-01T19:14:20.147" Score="15" Body="&lt;p&gt;I just ran some numbers based on Wikipedia statistics. I don't know how they define &amp;quot;incident or accident&amp;quot; but hull loss is pretty straightforward. That means it was written off.&lt;/p&gt;&#xA;&lt;div class=&quot;s-table-container&quot;&gt;&#xA;&lt;table class=&quot;s-table&quot;&gt;&#xA;&lt;thead&gt;&#xA;&lt;tr&gt;&#xA;&lt;th&gt;Aircraft type&lt;/th&gt;&#xA;&lt;th&gt;Total made&lt;/th&gt;&#xA;&lt;th&gt;Incidents/accidents&lt;/th&gt;&#xA;&lt;th&gt;Hull losses&lt;/th&gt;&#xA;&lt;/tr&gt;&#xA;&lt;/thead&gt;&#xA;&lt;tbody&gt;&#xA;&lt;tr&gt;&#xA;&lt;td&gt;DC-10&lt;/td&gt;&#xA;&lt;td&gt;368&lt;/td&gt;&#xA;&lt;td&gt;55 (14.2%)&lt;/td&gt;&#xA;&lt;td&gt;32 (8.3%)&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td&gt;L-1011&lt;/td&gt;&#xA;&lt;td&gt;250&lt;/td&gt;&#xA;&lt;td&gt;32 (12.8%)&lt;/td&gt;&#xA;&lt;td&gt;11 (4.4%)&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td&gt;727&lt;/td&gt;&#xA;&lt;td&gt;1832&lt;/td&gt;&#xA;&lt;td&gt;336 (18.3%)&lt;/td&gt;&#xA;&lt;td&gt;118 (6.4%)&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td&gt;737&lt;/td&gt;&#xA;&lt;td&gt;8725&lt;/td&gt;&#xA;&lt;td&gt;368 (4.3%)&lt;/td&gt;&#xA;&lt;td&gt;184 (2.1%)&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;tr&gt;&#xA;&lt;td&gt;747&lt;/td&gt;&#xA;&lt;td&gt;1514&lt;/td&gt;&#xA;&lt;td&gt;131 (8.6%)&lt;/td&gt;&#xA;&lt;td&gt;60 (4%)&lt;/td&gt;&#xA;&lt;/tr&gt;&#xA;&lt;/tbody&gt;&#xA;&lt;/table&gt;&#xA;&lt;/div&gt;&#xA;&lt;p&gt;All of these were introduced in the late 1960's. As you can see, the DC-10, L-1011, and 727, which are mostly retired, have pretty bad numbers. But the aircraft that are still being made and flown have much better stats. I think this is probably due to the fact that air travel gets safer all the time. The planes that had their heyday in the 70's and 80's fared poorly but the longer they continue to be produced, the less likely they are to crash.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="14897" LastEditDate="2021-04-30T15:45:25.070" LastActivityDate="2021-04-30T15:45:25.070" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="22602" PostTypeId="2" ParentId="22581" CreationDate="2015-11-01T20:39:22.713" Score="2" Body="&lt;p&gt;We back up our PF on the throttles during takeoff and landing on the DHC-6 Twin Otter. It's to ensure that the PF doesn't do anything goofy during an engine failure or other emergency (just a safeguard). &lt;/p&gt;&#xA;" OwnerUserId="12084" LastActivityDate="2015-11-01T20:39:22.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22603" PostTypeId="1" CreationDate="2015-11-01T21:14:21.620" Score="16" ViewCount="56870" Body="&lt;p&gt;I see these terms used almost interchangeably. To my understanding they both refer to the covering of an engine. Is there a technical difference between the two?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2015-11-02T14:59:32.813" LastActivityDate="2016-06-05T13:02:09.913" Title="What is the difference between a nacelle and a cowling?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22604" PostTypeId="2" ParentId="22603" CreationDate="2015-11-01T21:18:58.590" Score="17" Body="&lt;p&gt;The definition of a &lt;em&gt;nacelle&lt;/em&gt; refers to the housing of anything on the outside of an aircraft. Engines are the most common thing in these housings.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a streamlined housing or tank for something on the outside of an aircraft or motor vehicle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The definition of a &lt;em&gt;cowling&lt;/em&gt; is specifically a removable cover of the engine.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the removable cover of a vehicle or aircraft engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So a &lt;em&gt;nacelle&lt;/em&gt; refers to the whole covering of an engine that is outside the plane, typically on the wing. The &lt;em&gt;cowling&lt;/em&gt; would just be the removable part of this cover. As Jan Hudec commented, engines mounted in the nose, as is typical in smaller aircraft, would have a cowling to allow access and cooling to the engine, but technically not a nacelle, since the covering would be part of the fuselage.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-11-01T21:52:44.083" LastActivityDate="2015-11-01T21:52:44.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22605" PostTypeId="2" ParentId="22603" CreationDate="2015-11-01T22:51:50.557" Score="5" Body="&lt;p&gt;Nacelle comes from the french word &quot;nacelle&quot; which is the gondola or wicker basket suspended beneath a balloon. So, by analogy, many things that are outside the body of an aircraft, like the compartments that house the engines, can be called nacelles. A cowling is the covering of a vehicle's engine even if that motor is not inside a nacelle.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2015-11-01T22:51:50.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22606" PostTypeId="2" ParentId="22585" CreationDate="2015-11-01T23:32:48.823" Score="2" Body="&lt;p&gt;Modern fighter aircraft will be in service for at least 20, if not 40 years. This means they will see several updates, will carry several generations of weapons and be used in unexpected, unforeseen scenarios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Already today many combat aircraft designs are older than the pilots flying them. The relentless increase of weapon systems costs will mean that in future a smaller number of designs need to cover all demands, and do so for many more years with fewer platforms. Not giving those designs all capabilities which we can put into them will translate into a platform with clearly identifiable soft spots, and hostile weapon systems and tactics will try to exploit them to their advantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neglecting one of top speed, range, endurance, maneuverability, stealth or survivability will create a deadly weakness - maybe not within the first years those designs are fielded, but certainly for the majority of their lifetimes. Just consider the variety of tasks for a modern air superiority fighter:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Intercept intruders. What is a fighter worth that cannot climb up to an unknown threat in a hurry? With fewer aircraft around, the likely intercept distance will go up, too.&lt;/li&gt;&#xA;&lt;li&gt;Long-range strike. Let's face it, the F-15 and F-16 are used for strike missions a lot today. You have much more freedom in picking your base if the aircraft's range does't restrict you.&lt;/li&gt;&#xA;&lt;li&gt;Combat air patrol. You need to establish permanent air superiority with as few platforms as possible. This needs endurance.&lt;/li&gt;&#xA;&lt;li&gt;Dogfighting. In a low-intensity conflict the political directive is to visually identify the target in order to avoid embarrassing mistakes. You cannot always count on using BVR missiles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The old black-and-white world of the Cold War has changed into a multi-faceted world with many shades of grey, and needs versatile, flexible platforms.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-11-01T23:32:48.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22607" PostTypeId="2" ParentId="22603" CreationDate="2015-11-02T00:15:41.887" Score="10" Body="&lt;p&gt;The nacelle is a housing that is separate from the fuselage, that holds something, usually engines or some other equipment in an aircraft. The following figure shows some of the engine nacelles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tdXcJ.gif&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tdXcJ.gif&quot; alt=&quot;Engine nacelles&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A cowl or cowling is any part of the aircraft (or engine nacelle) that can be opened or removed (for inspection etc.). The following image shows cowlings in a nacelle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wOX40.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wOX40.jpg&quot; alt=&quot;Cowlings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: compositesworld.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are maintenance cowlings. Another type of cowlings (like NACA cowlings) serve to direct the airflow into the engine.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-02T00:38:30.920" LastActivityDate="2015-11-02T00:38:30.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22608" PostTypeId="2" ParentId="22556" CreationDate="2015-11-02T03:13:32.197" Score="2" Body="&lt;p&gt;You are exactly right that the pilot should have noticed he was in a stalled configuration due to (among other things) that the attitude indicator would be showing nose up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your guess about a 45-degree down angle is not quite right. That would cause a large increase in speed and constitute an uncontrolled dive. Not good, but definitely better than stalling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you pull the nose up and hold it there, then what happens is that the aircraft loses speed steadily until it stalls, then it falls rapidly. In a semi-stalled condition (what occurred to the AF447 flight), the aircraft will be buffeted from side to side as it slides to the ground in a nose up configuration. When this happens the controls become &quot;mushy&quot; and the aircraft becomes difficult to control. This happened to AF447 and that alone should have told them they were stalled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is no visual horizon and the pilots are flying blind it is easy to ignore or misinterpret the controls or focus on the wrong instrument. The pilots involved simply failed to realize they were stalled. The problem was compounded by poor command skills. Normally only ONE person is allowed to have the controls and that control can only be switched using an explicit protocol. The pilots of AF447 were not obeying this rule and both pilots were working the controls at the same time. The response of an Airbus to this behavior is to &lt;em&gt;average&lt;/em&gt; the two inputs. Obviously this created more confusion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One additional issue with the A330 is that it has what is called a &quot;supercritical&quot; airfoil shape to its wings which give it poor stall recovery characteristics, especially when fully loaded. When they tested the A330 in a simulator using the same conditions as in AF447 it took an expert pilot 23000 feet to recover from the type of stall they were in. So, once they had fallen below that altitude, they were dead and situation was unrecoverable.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-11-02T04:03:06.307" LastActivityDate="2015-11-02T04:03:06.307" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22609" PostTypeId="2" ParentId="22585" CreationDate="2015-11-02T04:30:32.263" Score="0" Body="&lt;p&gt;It is a legitimate question that is difficult to answer because there are little to no examples from actual warfare. What would happen when two pilots fight for real with $100 million aircraft on the line? It's hard to answer this definitively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot will depend on the combat context. Are we fighting over the ocean or in a big mountain range, like the Caucasus or Carpathian mountains? If it is useful for an aircraft to hide in the mountains, maneuverability can be extremely important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed is always very important because more speed increases the ability of the pilot to position the aircraft in a favorable location preliminary to the engagement. In exercises this matters less because both aircraft are placed in neutral or &quot;equal&quot; positions. In real combat usually positioning is unequal and whoever can get to the good spot first will have an advantage, often a decisive advantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firing a missile at someone you cannot see is problematic because how do you know they are the enemy? Also, they can see your missile on radar way ahead of time and evade it unless you get sufficiently close before firing. In real combat the enemy will not loiter out in the middle of the wild blue wonder just waiting for you to come and shoot at them. They will always position themselves in a secure location, such as close to the ground, where you can't see them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The defender will have a huge advantage if they have ground radar or an aerial radar, such as one on an aerostat, because they will see you coming and they can position their aircraft to ambush you. This is why &lt;a href=&quot;https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defenses&quot; rel=&quot;nofollow&quot;&gt;SEAD&lt;/a&gt; is so important. Against any opponent that has anywhere near your capability, it is suicidal to act due to the advantage fixed radar will provide. In a future war it is likely that specialized antennas will be made that are distributed and difficult to destroy. This will make aerial attacks on foreign soil very difficult, unless the enemy has primitive technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;BVR Issues&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the design of the T-50 is concerned, the focus on maneuverability is reasonable, especially for a defensive, air superiority fighter. As far as aircraft radar is concerned, be aware that it can only see (at best) in an 120-degree cone directly in front of the aircraft and if you use it, you light yourself up like a Christmas tree and everybody will know exactly where you are. Therefore, in a real war aircraft will, in many situations, not even use their radar, because it will give away their position, thereby allowing an enemy to pop up behind them and shoot.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-11-02T04:59:40.590" LastActivityDate="2015-11-02T04:59:40.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22610" PostTypeId="2" ParentId="18811" CreationDate="2015-11-02T06:23:43.687" Score="13" Body="&lt;p&gt;I can't improve on @egid's answer on efficiency or cost, but another point on constant speed units is related to 172s predominantly being trainers: fixed pitch props are easier to fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My first few lessons in the circuit were busy enough just getting the altitudes, positioning, radio calls and checks completed correctly. When I did differences training for variable pitch a few years later it suddenly became busy again, simply from trying to remember what the RPM and MP settings I was supposed to be using at each stage (generally 5 different combinations per circuit).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not &lt;em&gt;much&lt;/em&gt; harder, admittedly, but just having one dimension (the black throttle knob goes forward for more power or back for less power) was easier on my already over-taxed student brain than the two-dimensional variable pitch setup (black knob for power, blue for RPM; with blue going forward both when you want more power (takeoff) and when you're decreasing power (short final, in case you need to go-around)).&lt;/p&gt;&#xA;" OwnerUserId="11809" LastActivityDate="2015-11-02T06:23:43.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22612" PostTypeId="1" AcceptedAnswerId="22614" CreationDate="2015-11-02T10:16:42.963" Score="3" ViewCount="7056" Body="&lt;p&gt;Either I'm missing something, or &lt;a href=&quot;http://nats.aero/blog/2013/09/why-is-my-flight-delayed-in-the-fog/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; clearly suggests, that pilots are using ILS for landing only in bad weather conditions. Which could lead to an assumption, that in perfectly clear weather they're landing always or nearly always in visual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though I'm completely new to aviation, I was always sure that ILS is used on every landing procedure, no matter if weather conditions are good enough to do it visually. ILS landing seems to be faster, more precise, more safe, and thus -- in my naive opinion -- should be used whenever it is available (i.e. whenever ILS is commissioned and operational).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I missing?&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="2171" LastEditDate="2015-11-02T13:38:36.270" LastActivityDate="2015-11-03T05:54:45.590" Title="Is the ILS only used for landing when weather conditions are poor?" Tags="&lt;landing&gt;&lt;ils&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="1" ClosedDate="2015-11-02T21:46:59.197" ContentLicense="CC BY-SA 3.0" />
  <row Id="22613" PostTypeId="2" ParentId="22612" CreationDate="2015-11-02T10:31:14.833" Score="3" Body="&lt;p&gt;ILS is sometimes used in clear weather, it's at the discretion of the pilots and company policy (if it's commercial). Most pilots I know would prefer to fly a visual approach because flying is what they do - what's the point if the airplane does all the fun stuff? Even in instrument conditions pilots will often manually fly the ILS approach rather than using autopilot to keep up their skills. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ILS is only one out of several approach systems which exist. There are NDB, VOR, surveillance radar, and now GPS approaches which can be used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fly light aircraft from an airfield which has no approach aids whatsoever, when I fly from there it's always visual as it cannot be anything else. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-02T10:31:14.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22614" PostTypeId="2" ParentId="22612" CreationDate="2015-11-02T10:42:48.133" Score="6" Body="&lt;p&gt;I don't think that the article suggests &quot;pilots are using ILS for landing only in bad whether conditions&quot;. it simply says that under foggy (i.e. in bad weather), ILS is used as visual approach is not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of ILS is at the discretion of pilots with ATC permission. The ILS localiser and glideslope can still be used as a reference during the visual approach (even if the landing is not ILS). The decision is the pilots' as the visual indicators and glideslope may not match.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it is true that ILS is much more precise and safer, you are forgetting the human factor- the pilot may want to 'fly' the aircraft rather than letting the computer do it.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-02T10:42:48.133" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22615" PostTypeId="2" ParentId="22612" CreationDate="2015-11-02T10:52:46.907" Score="10" Body="&lt;p&gt;The relevant question is not whether or not the ILS system is used &lt;em&gt;at all&lt;/em&gt;, but &lt;em&gt;when&lt;/em&gt; the pilot switches from ILS to visual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the beginning of an ILS approach, the ILS signals function as a &lt;em&gt;navigation aid&lt;/em&gt;, helping to make sure that the aircraft is lined up correctly with the runway from a longer distance out than the runway itself would be visible clearly enough to the naked eye even in good weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At &lt;em&gt;some&lt;/em&gt; point during the approach, the runway will be clearly enough in sight that the pilot can actually land the plane visually. The latest point at which this is allowed to happen is the &quot;decision height&quot; -- if the runway is not reliably in sight by then, a go-around must be executed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower the decision height, the larger demands are placed on the accuracy and reliability of the ILS equpiment -- losing the ILS signal due to interference for a few seconds while still six miles out is much less critical than losing the signal for a few seconds right before touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It &lt;em&gt;is&lt;/em&gt; possible (if all the involved equipment is maintained and certified to high enough standards) to have a decision height of 0 feet so the ILS/autopilot flies the aircraft all the way to touchdown, but doing this requires all &lt;em&gt;other&lt;/em&gt; aircraft moving around on the airport surface to observe extended safety distances to the runway to minimize the risk of radio signals bouncing off their fuselages and sending a blind-landing aircraft astray. This can have bad effects for capacity, so in &lt;em&gt;normal&lt;/em&gt; operation landings are done with a nonzero decision height.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, most airports &lt;em&gt;don't&lt;/em&gt; spend the additional maintenance cost needed to certify their ILS systems for zero decision height (&quot;category III&quot; ILS operation), or do it only for some of their runways. In case of bad weather at busy times, some flights will just have to divert to other airports.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2015-11-02T12:51:12.987" LastActivityDate="2015-11-02T12:51:12.987" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22616" PostTypeId="1" AcceptedAnswerId="22618" CreationDate="2015-11-02T11:11:57.597" Score="2" ViewCount="617" Body="&lt;p&gt;If you've received traffic entry instructions from Heathrow Tower (sim) to fly left downwind for runway 9L, does that mean to be to the left of runway 9L (for a right-turning traffic pattern, where downwind is north of the runway) or to enter a left-turning traffic pattern? I ask because the latter would take you over runway 9R/27L and I'm unsure whether this is a problem or whether it's ok because of the difference in altitude between a plane in 9L's downwind and 9R's/27L's final/upwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if you've received clearance from runway 9L to depart north, should the departure be done from the traffic pattern? E.g. you take-off, turn crosswind, turn downwind then turn base and depart the airspace? Or should you continue straight until you've left the airspace, then change course?&lt;/p&gt;&#xA;" OwnerUserId="12091" LastEditorUserId="19" LastEditDate="2016-07-11T15:26:42.930" LastActivityDate="2016-07-11T15:26:42.930" Title="How is a traffic pattern oriented, entered and exited?" Tags="&lt;air-traffic-control&gt;&lt;flight-simulator&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22617" PostTypeId="1" CreationDate="2015-11-02T11:33:45.483" Score="2" ViewCount="200" Body="&lt;p&gt;At the risk of being marked as a duplicate question, i am raising my first ever question in aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have always wondered how/why of aircrafts positioning, ever since the &quot;lost&quot; plane of Malaysian airline. Here are few things that are still unclear to me - &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;We have fairly precise GPS service available to cars/phones etc. why cant the same be availale to planes? And more importantly, why cant the planes reciprocate with their own coordinates ? Better if it can be shared in real time ? What are the challenges?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I have read some about ADS-B a little and understand that it has its limitations.  owever, when we have so many human lives at stake, why is a better solution looked into/implemented?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The limitations that have been described for ADS-B systmes is pretty serious, given that many of the aircraft today travel through horizon boundaries.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;How exactly do &quot;people&quot; get to know of a aircraft and/or its position in order to &quot;potentially&quot; strike it using a missile etc? Is any of ADS-B data available publicly allowing a plane to be tracked by &quot;anyone&quot;? if so, why also, isnt that encrypted, and if not, why not?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;My thought process is mostly around &quot;how can someone track a plane without being part of the ATS system/network&quot;? &lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;What are the areas of our planet not covered by navigational satellites ?  There are references to lack of navigational satellite coverage in many areas on earth.  For that reason, I want to understand more on that topic.  For an aeroplane, flying on a given route, transmitting its position to a satellite above, what are the potential challenges?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12090" LastEditorUserId="7532" LastEditDate="2015-11-02T12:35:20.960" LastActivityDate="2015-11-02T12:35:20.960" Title="GPS transmission from Aircraft" Tags="&lt;navigation&gt;&lt;gnss&gt;" AnswerCount="0" CommentCount="12" FavoriteCount="1" ClosedDate="2015-11-02T12:31:44.087" ContentLicense="CC BY-SA 3.0" />
  <row Id="22618" PostTypeId="2" ParentId="22616" CreationDate="2015-11-02T12:58:01.543" Score="3" Body="&lt;p&gt;The instruction to join a &quot;left downwind&quot; is used to clear an aircraft into a standard traffic pattern with lefthand turns. The word &quot;left&quot; could be omitted, as only right turns and righthand traffic patterns are called with &quot;right&quot;. In the case of EGLL - London Heathrow the standard pattern would be a northern traffic pattern for runways 09L/09R and a southern traffic pattern for runway 27L/27R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you should come to the unlikely situation that you are VFR and want to depart from Heathrow, the clearance to leave the CTR in a northerly direction would be best executed leaving the crosswind, but clarification on frequency never killed anybody:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A: Heathrow Tower, G-ABCD, request leave CTR direct northbound after crosswind 09L.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A: Heathrow Tower, G-ABCD, request heading 360 after turning crosswind 09L.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;When departing an aerodrome with traffic, it is unwise to leave the CTR along the extended centerline/upwind, as you are impeding other traffic, especially in slower aircraft.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-11-02T12:58:01.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22619" PostTypeId="1" AcceptedAnswerId="22620" CreationDate="2015-11-02T14:13:58.263" Score="13" ViewCount="8877" Body="&lt;p&gt;Is it possible? Are there some such accidents in human history? Is there any rules or systems design to protect airplanes?&lt;/p&gt;&#xA;" OwnerUserId="12092" LastEditorUserId="12092" LastEditDate="2015-11-04T17:46:18.013" LastActivityDate="2015-11-04T17:46:18.013" Title="Is it possible that meteor could strike a commercial airliner?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;" AnswerCount="8" CommentCount="12" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22620" PostTypeId="2" ParentId="22619" CreationDate="2015-11-02T14:23:52.460" Score="26" Body="&lt;p&gt;A meteorite could hit an airplane, sure. There's no known cases of it happening because meteorites which survive atmospheric entry are very rare, and airplanes are pretty small so the likelihood of it happening is extremely low. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-11-03T08:58:34.293" LastActivityDate="2015-11-03T08:58:34.293" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="22621" PostTypeId="2" ParentId="22619" CreationDate="2015-11-02T15:05:03.530" Score="46" Body="&lt;p&gt;Yes, it is &lt;em&gt;possible&lt;/em&gt;, however unlikely!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://cdn.onderzoeksraad.nl/documents/report-mh17-crash-en.pdf&quot;&gt;final report into the downing of MH17&lt;/a&gt; investigated the possibility that the aeroplane was hit by &quot;meteor or space debris&quot;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In section 3.5 a number of scenarios are analysed that relate to the possible source or sources of the object that perforated the aeroplane. These include meteor and space debris.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It was concluded that&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The chance of a meteor striking an aeroplane was calculated as being one event in 59,000 to 77,000 years. This value was obtained from the University of Pittsburgh's Department of Geology and Planetary Science and was originally part of the NTSB's investigation into the 1996 accident to TWA flight 800 (see NTSB Report AAR-00/03, dated 23 August 2000)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="100" LastEditorUserId="100" LastEditDate="2015-11-03T08:49:08.550" LastActivityDate="2015-11-03T08:49:08.550" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22622" PostTypeId="1" CreationDate="2015-11-02T15:48:14.003" Score="2" ViewCount="425" Body="&lt;p&gt;DO-254 provides guidance for the development of airborne electronic hardware and it is recognized by the FAA in 2005 via AC 20-152 as a means of compliance for the design of complex electronic hardware.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is DO-254 only applicable for electronics that perform some kind of 'logic' operations or is it also intended to be used to prove compliance for non-logic electronics, e.g. like power electronics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some may argue that power electronics as 'simple' but I believe todays electronic designs have to be considered fairly complex.&lt;/p&gt;&#xA;" OwnerUserId="11537" LastEditorUserId="13197" LastEditDate="2016-04-25T10:26:15.530" LastActivityDate="2016-04-25T10:26:15.530" Title="Does RTCA/DO-254 apply to power electronics?" Tags="&lt;aircraft-certification&gt;&lt;aircraft-development&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22623" PostTypeId="2" ParentId="22619" CreationDate="2015-11-02T16:21:04.707" Score="4" Body="&lt;p&gt;Possible, but unlikely. There are no documented instances of a meteorite striking an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the meteoroids that become meteors are of the size of a grain of sand, and will burn up by the time they reach the cruising altitude of the commercial airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A hundred or so meteors of the size required for &lt;a href=&quot;http://www.geert.io/the-frequency-of-large-meteoroids.html&quot; rel=&quot;nofollow&quot;&gt;impact at high altitudes strike earth every hour&lt;/a&gt;. At the terminal velocity of the meteors, the aircraft is practically stationary and the probability of a meteor striking an aircraft is simply the ratio of the total area of aircraft in air to the total surface area of earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Around 4000 aircraft are in skies at any given time- each with a projected area of ~300 $m^{2}$ (if we are being generous). This means that the probability of an aircraft getting hit by a meteor is ~$2 \times 10^{-9}$ at any point of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that each aircraft makes a 8 hour flight (again, being generous), the probability of that getting hit by a meteor is ~$10^{-6}$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically the probability of an aircraft getting hit by a meteor is pretty small; Again, if we continue to operate aircraft at the rate we do, one of them will certainly get hit by a meteor.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-02T16:21:04.707" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="22624" PostTypeId="1" CreationDate="2015-11-02T17:09:40.067" Score="2" ViewCount="585" Body="&lt;p&gt;What alternatives are available to using a permanent mount to place a GoPro on the inside ceiling center of a Cessna 172?  &lt;/p&gt;&#xA;" OwnerUserId="12060" LastEditorUserId="1696" LastEditDate="2015-11-02T17:13:22.523" LastActivityDate="2015-11-12T09:23:18.370" Title="What types of non-permanent GoPro mounts exist for the ceiling of a Cessna 172?" Tags="&lt;flight-training&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-11-13T15:56:10.083" ContentLicense="CC BY-SA 3.0" />
  <row Id="22625" PostTypeId="2" ParentId="22612" CreationDate="2015-11-02T17:12:46.267" Score="5" Body="&lt;p&gt;Pilots don't (usually) do &lt;em&gt;autoland&lt;/em&gt;, i.e. having autopilot follow the ILS all the way down to the ground, in good weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using autoland requires that no other aircraft or vehicles pass in designated protected area around the ILS transmitters, because they could disturb the signal and cause the aircraft to land outside the runway like this &lt;a href=&quot;http://avherald.com/h?article=445873f3&quot; rel=&quot;nofollow&quot;&gt;Singapore Airlines B777 in Munich&lt;/a&gt; when they tried autoland in good weather for practice and did not tell ATC/ask them for cooperation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because these procedures restrict operations, the tower controller won't normally apply them if the weather is good enough to use visual or CAT I approaches in which the final part of the approach must be flown by pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, visual approach just means that the pilot must have visual reference to the runway. They are still free to use any additional reference and pilots will often tune the ILS (or the FMS will even tune it automatically when the approach procedure is selected) to verify they are approaching the intended runway and for cross-checking the glide-slope.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-11-03T05:54:45.590" LastActivityDate="2015-11-03T05:54:45.590" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22626" PostTypeId="2" ParentId="22590" CreationDate="2015-11-02T17:30:17.290" Score="1" Body="&lt;p&gt;Speed brakes or air brakes is the same word and has the same meaning, mainly is used only in the air. Once the pilot decide to use them 3 or 4 of the spoilers on the wing will deflect little bit but not fully extend. purpose of using it is to 1. Reduce the IAS ( indicated air speed ) 2. To increase rate of descent beacause it will ad ( drag ) when you use them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoiler of also called ground spoilers is only deployed and fully extended once the airplane weight is on the wheel which basically is on landing or when rejecting takeoff. They work by deflecting all spoilers on the wing in an angle that kills lift thus having weight and it helps the airplane decelerate cause you have the whole airplane weight on the wheels&lt;/p&gt;&#xA;" OwnerUserId="12097" LastActivityDate="2015-11-02T17:30:17.290" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22627" PostTypeId="2" ParentId="22622" CreationDate="2015-11-02T17:57:58.300" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22211&quot; rel=&quot;nofollow&quot;&gt;description of AC 20-152&lt;/a&gt; answers your question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This advisory circular (AC) applies to manufacturers and installers of &lt;strong&gt;&lt;em&gt;products or appliances incorporating complex custom micro-coded components with hardware design assurance levels of A, B, and C. These complex custom micro-coded components include application specific integrated circuits (ASIC), programmable logic devices (PLD), field programmable gate arrays (FPGA), or similar electronic components&lt;/em&gt;&lt;/strong&gt; used in the design of aircraft systems and equipment. This AC provides a means (but not the only means) to gain Federal Aviation Administration (FAA) approval by showing the equipment design is appropriate for its intended function. Further, using this AC will help you satisfy airworthiness requirements when these types of electronic components are implemented&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&quot;Power Electronics&quot; is a term so broad as to be nearly meaningless, but it doesn't matter: If the devices in question are designed to be installed on an airplane; have a DAL of A, B, or C (a failure would be Catastrophic, Hazardous, or Major respectively); and incorporate ASICs, FPGAs, or other circuitry with custom microcode then the FAA's guidance indicates you should comply with DO-254.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note that anything you intend to install on an aircraft needs to demonstrate &lt;em&gt;to the FAA's satisfaction&lt;/em&gt; that it is not hazardous to safety of flight in both normal and failure conditions, and that it does what you say it does.&lt;br&gt;&#xA;Documented compliance with DO-254's guidance is one &lt;em&gt;acceptable&lt;/em&gt; means of demonstrating the first of those elements (by showing robustness in the design, and graceful failure modes), though it is not the only means. (In other words if you're building a panel-mount cell phone charger or something equally ridiculous nothing indicates that you &lt;em&gt;must&lt;/em&gt; comply with DO-254, but the FAA may ask you to comply if they feel your device is such that DAL A, B, or C is appropriate.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2015-11-03T17:21:12.547" LastActivityDate="2015-11-03T17:21:12.547" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22628" PostTypeId="2" ParentId="22612" CreationDate="2015-11-02T18:17:40.957" Score="1" Body="&lt;p&gt;As a student pilot that isn't IFR trained yet, we always fly visually and don't use the ILS. How I land depends on if it's at a towered airport, non-towered airport, or if I'm coming in from 10 miles out or if I'm already in the vicinity of the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TL;DR what you're missing is that most pilots start out as VFR only and the last thing you want is to be distracted by things inside the cockpit like GPS devices, tuning an OBS, loads of instructions from tower controllers, etc. Every pilot needs to able to fly the airplane without the assistance of an ILS or a GPS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;General Final Approach&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On final approach, if flying visually, we power up if the aiming point is descending in the windscreen and we power down if it's climbing. Power is altitude, but may require a corresponding pitch adjustment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we get slow, we nose down and vice-versa if our speed is a little high. We adjust power as necessary based upon our pitch adjustment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Non-towered Landings&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are fairly straightforward. We enter the pattern for the runway we've chosen at a 45-degree angle to the downwind leg. We then turn base then final and end up 1-2 NM out on final, ideally 500-600 feet AGL and descending at 500 FPM. Again, this is a purely visual landing where we're focusing our aiming point in the window and trying to keep it steady by using power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Towered Airport Landings&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the towered landings I've done the controller has said to advise when 2 miles out and told us to aim for a base leg for runway X. We then fly a decently long base leg, turn final ideally at 500-600 feet AGL, and land just like at non-towered airports. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller could instruct us to do a 10-mile straight in, enter on the downwind, enter on base, etc., but it just depends on traffic and controller load. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have yet to be instructed to use the ILS as a visual (VFR) pilot and I wouldn't want to b/c as a student, it's very helpful to learn ground references, ground track, crosswind correction, etc. without the assistance and &lt;em&gt;distraction&lt;/em&gt; of in-the-cockpit devices.&lt;/p&gt;&#xA;" OwnerUserId="12098" LastActivityDate="2015-11-02T18:17:40.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22629" PostTypeId="2" ParentId="22590" CreationDate="2015-11-02T20:41:43.807" Score="4" Body="&lt;p&gt;In my mind these terms all refer to the same thing with 'Lift Dumper' being a more British/European term. But to help illustrate the source of the confusion a quote from the A300 AMM&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The lift dumping function is achieved by control surfaces on the upper&#xA;surface of each wing.&#xA;In flight, the speedbrake function is achieved on each wing by :&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Two inner speedbrakes&lt;/li&gt;&#xA;&lt;li&gt;Two outer speedbrakes&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;On the ground, the lift dumping function is achieved on each wing by :&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The two inner speedbrakes&lt;/li&gt;&#xA;&lt;li&gt;The two outer speedbrakes&lt;/li&gt;&#xA;&lt;li&gt;Three spoilers.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The spoilers are also used in roll control, when they complement the action&#xA;of the ailerons.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The A320 AMM&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Five spoilers numbered 1 thru 5 inboard to outboard are provided on the rear&#xA;upper surface of each wing.&#xA;The spoilers are used for:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Roll function&lt;/li&gt;&#xA;&lt;li&gt;Speedbrake function&lt;/li&gt;&#xA;&lt;li&gt;Ground spoilers function&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So really, the spoiler is the component, while lift dump and speedbrake refer to function the spoiler is providing.&lt;/p&gt;&#xA;" OwnerUserId="2341" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-02T20:41:43.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22630" PostTypeId="1" AcceptedAnswerId="22636" CreationDate="2015-11-03T02:42:06.080" Score="2" ViewCount="3265" Body="&lt;p&gt;I'm trying to understand the relation between the Lift Coefficient and the Angle of Attack using PEP software for the A320 IAE. However, I notice that often for a given Angle of Attack, there could be more than one Lift Coefficient (&quot;slightly different&quot; but different).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it an error or a real issue? If yes, what are the standard conditions assumed for the Cl vs AOA graph?&lt;/p&gt;&#xA;" OwnerUserId="8374" LastActivityDate="2017-07-12T16:31:09.390" Title="What is the relation between the Lift Coefficient and the Angle of Attack?" Tags="&lt;aerodynamics&gt;&lt;airbus-a320&gt;&lt;lift&gt;&lt;angle-of-attack&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22632" PostTypeId="1" AcceptedAnswerId="22635" CreationDate="2015-11-03T04:30:44.353" Score="9" ViewCount="3746" Body="&lt;p&gt;The Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/FIM-92_Stinger&quot; rel=&quot;nofollow&quot;&gt;the FIM-92 B variant of the Stinger Missile&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this version, the infrared seeker head was replaced by a combined IR/UV seeker that utilized rosette scanning. This resulted in achieving significantly higher resistance to enemy countermeasures (Flares) and natural disturbances. Production ran from 1981 to 1987, a total of 600 missiles were produced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm assuming &quot;IR/UV&quot; means &quot;infrared/ultraviolet.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do aircraft (or jet engines) really have a strong ultraviolet signature? If so, how is it formed? Is it only evident at high airspeeds?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Also, what on Earth could it be talking about by &quot;natural disturbances&quot;?)&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="4474" LastEditDate="2015-11-03T21:21:19.477" LastActivityDate="2018-06-06T13:16:45.023" Title="What is the ultraviolet signature, if any, of aircraft and jet engines?" Tags="&lt;jet-engine&gt;&lt;military&gt;&lt;missiles&gt;&lt;sensors&gt;&lt;missile-lock&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22633" PostTypeId="1" AcceptedAnswerId="22634" CreationDate="2015-11-03T04:45:06.940" Score="3" ViewCount="949" Body="&lt;p&gt;The flight path from Taipei, Taiwan, to Tianjin, China, does not go directly to Tianjin in a straight line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, it heads directly north, then banks left (west) before heading north again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nqLM3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nqLM3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(Actual flight CCA188, source: &lt;a href=&quot;https://fr.flightaware.com/live/flight/CCA188/history/20151101/1045Z/RCSS/ZBTJ&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightAware&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Possible route: PIANO L3 VIOLA R596 OKATO W13 PINOT B221 OKTUG W506 HGH W554 DOGVI A470 PIX A593 VYK VYK9A/16R (used by virtual crews on &lt;a href=&quot;http://www.airspacemag.com/flight-today/welcome-to-cyberairspace-96876957/&quot; rel=&quot;nofollow noreferrer&quot;&gt;simulation networks&lt;/a&gt;, source: &lt;a href=&quot;http://vataware.com/flight/554ec8cea7656570cb000005&quot; rel=&quot;nofollow noreferrer&quot;&gt;VATAware&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know why this is?&lt;/p&gt;&#xA;" OwnerUserId="12106" LastEditorUserId="3201" LastEditDate="2015-11-03T07:45:24.983" LastActivityDate="2015-11-03T10:56:55.103" Title="Why is the flight path from Taipei to Tianjin not a straight line?" Tags="&lt;airline-operations&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22634" PostTypeId="2" ParentId="22633" CreationDate="2015-11-03T07:02:49.527" Score="6" Body="&lt;p&gt;This will be due to routing and the airways available. Looking at the &lt;a href=&quot;http://eaip.caa.gov.tw/eaip/history/2015-10-29/html/eAIP/RC-ENR-6-en-TW.html#ENR-6&quot; rel=&quot;noreferrer&quot;&gt;Enroute Chart&lt;/a&gt; for the Taipei FIR, you will notice that there is no direct route northbound, but all routes have a north-east direction to remain clear of restricted area RCR8 (GND - FL370). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bGN9x.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bGN9x.png&quot; alt=&quot;AIP TAIPEI&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://eaip.caa.gov.tw&quot; rel=&quot;noreferrer&quot;&gt;http://eaip.caa.gov.tw&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight most likely, as I cannot find the flightplan, departed RCTP - Taipei via the DRAKE1A or DRAKE1B SID, leading to SULEM. Thereafter it continued westbound on the respective airways within China to then join another airway north.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is consistent with the flightprofile tracked on flightware for &lt;a href=&quot;http://de.flightaware.com/live/flight/EVA730/history/20151028/0057ZZ/RCTP/ZBTJ&quot; rel=&quot;noreferrer&quot;&gt;EVA730 from RCTP to ZBTJ&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fqwBu.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fqwBu.png&quot; alt=&quot;Flightaware track&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: www.flightaware.com)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-11-03T07:02:49.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22635" PostTypeId="2" ParentId="22632" CreationDate="2015-11-03T09:13:39.420" Score="13" Body="&lt;p&gt;Your assumption is correct - it is indeed about infrared (wavelength between 750 nm and 10,000 nm) and ultraviolet (wavelength between 100 nm and 400 nm) radiation. The sensor detected two specific wavelengths, one from each range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every body has an &lt;a href=&quot;https://en.wikipedia.org/wiki/Thermal_radiation&quot; rel=&quot;noreferrer&quot;&gt;electromagnetic radiation&lt;/a&gt; which is consistent with its temperature. This radiation has an intensity distribution which shifts to shorter wavelengths with temperature. By comparing the intensity of the IR and UV parts of this radiation, the sensor can much better distinguish between radiation sources of different temperature. Flares are normally hotter than engine exhausts, so by detecting an excess of UV radiation, the sensor can distinguish between flares and exhaust pipes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G8e6f.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G8e6f.png&quot; alt=&quot;&amp;quot;Wiens law&amp;quot; by 4C - Own work, based on JPG version. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Wiens_law.svg#/media/File:Wiens_law.svg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Wiens law&quot; by 4C - &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Wiens_law.svg#/media/File:Wiens_law.svg&quot; rel=&quot;noreferrer&quot;&gt;Own work, based on JPG version&lt;/a&gt;. Licensed under CC BY-SA 3.0 via Commons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Natural disturbances means reflected sunlight off a polished aircraft surface or canopy, or off lakes or windows on the ground. Even after filtering by the upper atmosphere, sunlight will contain much more UV radiation than your average exhaust pipe, and glares were a big distraction to early thermal seekers. Sunlight would correspond to the green line in the diagram above, while the exhaust would be even below the dark red line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the absolute intensity also goes up with temperature, but would not help in identifying the temperature of a target if only one wavelength is observed. A more distant, hotter target would cause the same intensity than a colder, closer one. By sensing two wavelengths, the sensor could much better tell an exhaust pipe from other heat sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question directly: The UV signature of the aircraft itself is practically zero except for the reflection of the UV part of sunlight, and the active UV emission of a jet engine is extremely low and concentrated around its exhaust when seen from behind. Lighting the afterburner will increase the UV radiation, but it will still be much less relative to the IR radiation that that of, say, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flame&quot; rel=&quot;noreferrer&quot;&gt;burning magnesium&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-03T09:43:48.143" LastActivityDate="2015-11-03T09:43:48.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22636" PostTypeId="2" ParentId="22630" CreationDate="2015-11-03T09:55:04.473" Score="2" Body="&lt;p&gt;Normally the relation is &lt;a href=&quot;https://aviation.stackexchange.com/questions/14508/calculating-a-finite-wings-lift-from-its-sectional-airfoil-shape/14559#14559&quot;&gt;linear within the practical range of angles of attack&lt;/a&gt; used in flight. However, the Mach number and the Reynolds number will cause shifts. For the Mach effect, use the Prandtl-Glauert rule in subsonic flow up to Mach 0.7: $$(\alpha - \alpha_0)_{Mach} = (\alpha - \alpha_0)_{incompressible}\cdot\sqrt{1-Mach^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A higher &lt;a href=&quot;https://aviation.stackexchange.com/questions/7533/why-simple-paper-planes-fly-better-than-most-realistic-paper-plane-models/7536#7536&quot;&gt;Reynolds number&lt;/a&gt; means a relatively thinner boundary layer, and since the boundary layer on the suction side of the airfoil grows in thickness with increasing angle of attack, the same airfoil will have less boundary layer growth at a higher Reynolds number. This translates into a higher effective angle of attack at the same geometrical angle, so the lift curve slope becomes steeper and will reach stall at a higher angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no standard conditions, but a proper lift curve graph should note both the Mach and Reynolds number for which it is valid.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-11-03T22:52:01.483" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22637" PostTypeId="2" ParentId="22632" CreationDate="2015-11-03T10:08:59.550" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the ultraviolet signature, if any, of aircraft and jet&#xA;  engines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The exhaust plume of the jet engine that has radiation which flickers within the &lt;a href=&quot;https://www.tanningtraining.com/btc/ch2.html?prodid=2&quot; rel=&quot;nofollow&quot;&gt;Ultraviolet Range&lt;/a&gt; and the ultraviolet light radiation that exists as a result of a pressure wave on the tip or leading edge of the aircraft  that is moving fast enough to create a sonic pressure wave. Several different constituents of a jet engine – accretion flow; stellar magnetosphere; winds and inner parts of the accretion disk radiate in the Ultraviolet spectrum. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm assuming &quot;IR/UV&quot; means &quot;infrared/ultraviolet.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Correct&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, what on Earth could it be talking about by &quot;natural&#xA;  disturbances&quot;?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this context, what it means is that Infra-Red (IR) is the main method of tracking the target. Ultraviolet(UV) is used in addition to discriminate the target from flares and &quot;natural disturbances&quot; like direct sunlight or sunlight reflecting from clouds as they usually have totally different amount of UV radiation compared to the target. Basically they are referring to the Proportional Guidance system of the Stinger MANPAD. Since the primary job  of MANPADS like Stinger is to  stay locked on, the  heat seekers’ fields of view are usually small to prevent distraction from competing sources.Seeker optics magnify IR/UV signatures emitted by distant aircraft,keeping track of the target aircraft is another matter altogether&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2015-11-03T10:08:59.550" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22638" PostTypeId="2" ParentId="22619" CreationDate="2015-11-03T10:31:42.213" Score="7" Body="&lt;p&gt;When I served at a military airport in Hungary I read a written report of a MIG-21, supposedly hit by meteor or space debris, crashing the cabin canopy. It was flying with afterburner at high altitude and the pilot's hand was on the throttle lever waiting for instructions. This is why he could manage to slow down and survive. Not an airliner though.&lt;/p&gt;&#xA;" OwnerUserId="12110" LastActivityDate="2015-11-03T10:31:42.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22640" PostTypeId="1" AcceptedAnswerId="22643" CreationDate="2015-11-03T10:59:36.170" Score="31" ViewCount="5918" Body="&lt;p&gt;I have some confusion concerning the ground effect.&#xA;If we take two applications: Aircraft and Cars, they seem to have completely opposite effects.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ground effect (aerodynamics)&lt;/a&gt;, we can read:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;During normal flight, the upper wing surface experiences reduced static air pressure and the lower surface comparatively higher static air pressure. Flying close to a surface increases air pressure on the lower wing surface, nicknamed the &amp;quot;ram&amp;quot; or &amp;quot;cushion&amp;quot; effect, and thereby improves the aircraft lift-to-drag ratio. The lower/nearer the wing is vs. the ground, the more pronounced the ground effect becomes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I can understand this, the air gets 'trapped' between the wing and the surface (and as consequence the pressure on the underside of the wing goes up)&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Cars&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;However, from &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_(cars)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ground effect (cars)&lt;/a&gt; we read:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Designers shifted their efforts at understanding air flow around the perimeter, body skirts, and undersides of the vehicle to increase downforce with less drag than compared to using a wing.&lt;/p&gt;&#xA;&lt;p&gt;This kind of ground effect is easily illustrated by taking a tarpaulin out on a windy day and holding it close to the ground: it can be observed that when close enough to the ground the tarp will be drawn towards the ground. This is due to Bernoulli's principle; as the tarp gets closer to the ground, the cross sectional area available for the air passing between it and the ground shrinks. This causes the air to accelerate and as a result pressure under the tarp drops while the pressure on top is unaffected, and together this results in a net downward force. The same principles apply to cars.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The cross sectional area decreases, causing a higher velocity. This higher velocity decreases the pressure, causing the tarpualin to go down.&lt;/p&gt;&#xA;&lt;p&gt;This confuses me, as it seems that the same situation (a plate in the vicinity of a surface) causes two completely opposite effects.&lt;/p&gt;&#xA;&lt;p&gt;Both the &amp;quot;trapping air -&amp;gt; pressure goes up&amp;quot;  as well as &amp;quot;trapping air -&amp;gt; velocity goes up -&amp;gt; pressure goes down&amp;quot; explanation seem reasonable to me.&lt;/p&gt;&#xA;&lt;p&gt;This made me wonder:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Why the ground effect has such a different outcome for wings and cars?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;If I have a plate under an angle close to the ground, will the air be trapped, creating an air cushion pushing the plate up, or will the air accelerate, causing the plate to be pushed down? Does it have to do with some degree of area decreasing?&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2020-06-17T18:50:43.723" LastActivityDate="2020-06-17T18:50:43.723" Title="Why the ground effect has such a different outcome for wings and cars?" Tags="&lt;ground-effect&gt;" AnswerCount="6" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="22641" PostTypeId="2" ParentId="22593" CreationDate="2015-11-03T11:10:48.853" Score="4" Body="&lt;p&gt;Often the police helicopter is out looking for the target.  A circle is a search pattern.   News typically has a known target they just need a shot of.  &lt;/p&gt;&#xA;" OwnerUserId="8649" LastActivityDate="2015-11-03T11:10:48.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22642" PostTypeId="2" ParentId="22640" CreationDate="2015-11-03T11:11:24.447" Score="3" Body="&lt;p&gt;The main difference between the two cases is that the wing generates lift by inducing a downward wind component. When this downward wind component is close enough to the ground, an increase in lift will occur according to the explanation you posted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two effects have the same name, but are explained by different physical principles. Just think of the distances between a wing and the ground (a few meters) and between a car chassis and the ground (a few centimetres). A car is not a lifting body and will not induce a downwind, therefore this will not cause an upward force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The car ground effect is just &quot;another&quot; ground effect, which is explained correctly by your quote.&lt;/p&gt;&#xA;" OwnerUserId="6859" LastActivityDate="2015-11-03T11:11:24.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22643" PostTypeId="2" ParentId="22640" CreationDate="2015-11-03T11:46:04.210" Score="41" Body="&lt;p&gt;It actually has &lt;strong&gt;exactly the same&lt;/strong&gt; outcome! Well, in reverse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wings generate lift by forcing air down (one way or another, let's not go into details). When the wings are close to the ground, the air that is forced down can't get out of the way, resulting in a higher pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cars generate downforce by forcing air up. When air close to the ground is forced up, it can't be replaced by 'new' air easily. This results in a low pressure, sucking the car down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ground effect is thus exactly the same in either case: air that is either pushed out or pulled in, cannot be replenished quickly enough due to the ground being in the way. The difference in outcome is because a wing is attached at a positive angle w.r.t the ground, whereas a car is shaped like a very thick wing at a negative angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A comparison could be a hovercraft on the one hand, which is lifted off the ground almost exclusively by ground effect (if you were to drop a hovercraft from a plane, it wouldn't matter much whether it was powered up or not). On the other hand, a vacuum cleaner, which is sucked down to the floor &lt;em&gt;exclusively&lt;/em&gt; by ground effect (indeed, Feynman's sprinkler experiment will tell you it is not sucked down because of the upwards acceleration of air - only the 'engine' part of your vacuum is forced down by momentum exchange. Test this by holding the vacuum in the air - you won't feel it 'pull' at all).&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2020-06-17T06:27:09.783" LastActivityDate="2020-06-17T06:27:09.783" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="22644" PostTypeId="2" ParentId="22640" CreationDate="2015-11-03T12:03:00.057" Score="19" Body="&lt;p&gt;Because they are designed differently. As you've yourself pointed out, while an aircraft produces lift, the racecars produces downforce i.e. lift directed downwards. The following figure shows the design of the wing of an aircraft and the front wing of a racing car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yx4le.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yx4le.png&quot; alt=&quot;Ground Effect&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Ground Effect Aerodynamics&lt;/em&gt; by Erjie Cui and Xin Zhang&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the downforce of the cars is the lift towards the bottom. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the wings are close to the ground , two things happen- the effective span is increased due to the interference of ground with vortices (within a wingspan).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xTZIT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xTZIT.jpg&quot; alt=&quot;Ground effect vortices&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: ghdstudios.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Still closer to the ground (around 1/4th span), the air flow between the wing and the ground is compressed to form an air cushion. The pressure on the lower surface of the wing is increased creating additional lift.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The net result is the increase in lift and decrease in (induced) drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of cars, the same thing happens, with the force in the downward direction. As the air is 'trapped' in the the gap between the suction surface (underside in case of a car) and the ground, it initially accelerates. As the height is reduced, the flow accelerates more, resulting in less pressure and more downforce.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-03T12:03:00.057" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22645" PostTypeId="2" ParentId="22640" CreationDate="2015-11-03T13:51:09.900" Score="6" Body="&lt;p&gt;Remember that lift means the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;downward acceleration of an air mass&lt;/a&gt;. This bends the aerodynamic force vector backwards, so a small part of the pressure force acts against the direction of motion.&lt;/p&gt;&#xA;&lt;p&gt;If the ground blocks this bending, less of the aerodynamic force will be felt as drag. This is true regardless of the direction of this force - it can be up or down. The closer the distance between wing and ground is, the more &lt;a href=&quot;https://aviation.stackexchange.com/questions/311/what-is-ground-effect/11396?s=5%7C0.0880#11396&quot;&gt;this effect can be observed&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The difference between the ground effect of an aircraft and that of a car is their angle of attack and the resulting direction of lift: Up in case of the aircraft and down in case of the car. The magnitude of the resulting force is not changed much, only its backward tilt is reduced, which results in a dramatic drag decrease.&lt;/p&gt;&#xA;&lt;p&gt;The car body acts also as a wing, albeit one with a small aspect ratio. All the racecar designers did is to replace the top-mounted wing (which did not feel much ground effect) by the car body itself (which is much closer to the ground). By keeping the entry area under the front bumper smaller than the exit area under the rear bumper, the car body acts like a wing at a negative angle of attack, and ground effect makes its downforce creation quite efficient.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aeHxR.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aeHxR.gif&quot; alt=&quot;Widening gap between car body and ground in side view&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Widening gap between car body and ground in side view (picture &lt;a href=&quot;http://www.insideracingtechnology.com/tech110underwing.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Skirts make this more efficient by preventing air entering from the side, but in the ever evolving tug-of-war between race car engineers and regulators they and some aspects of car bottom shaping have become less efficient in recent times.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-06-17T09:31:46.237" LastActivityDate="2020-06-17T09:31:46.237" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="22646" PostTypeId="2" ParentId="22632" CreationDate="2015-11-03T13:57:11.087" Score="2" Body="&lt;p&gt;You're correct that IR/UV means Infra red/Ultra Violet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the aircraft (or its exhaust) does not have any appreciable UV emission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MANPADS such as Stinger using a IR detector can be confused by launching flares that have the same (or similar) IR signature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason the UV sensor was added was that that it can be used to discriminate the target by detecting the 'UV shadows' cast by an aircraft in a background sky radiance of atmospherically scattered solar UV. These will be different for the actual aircraft and the flares.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some Soviet missiles achieved the same effect by using IR sensors in two different wavelengths, while most modern missiles have sensors of sufficiently high resolution to discriminate the target.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-03T14:34:30.703" LastActivityDate="2015-11-03T14:34:30.703" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22650" PostTypeId="1" AcceptedAnswerId="22651" CreationDate="2015-11-03T18:31:33.333" Score="5" ViewCount="1073" Body="&lt;p&gt;I recently had the opportunity to try a 737 simulator and one thing that struck me was the placement of the trim wheels. They are located dangerously close to the seats and, man, do they spin fast. I can only imagine the pain if you accidentally leave the manual trimming handle retracted or if you get some hair stuck in there. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are they placed this way? I would assume that a less prominent placement would still allow easy access for manual trimming. &lt;/p&gt;&#xA;" OwnerUserId="11665" LastActivityDate="2015-11-03T18:37:48.913" Title="Why are the 737 trim wheels located so close to the seats?" Tags="&lt;flight-controls&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22651" PostTypeId="2" ParentId="22650" CreationDate="2015-11-03T18:37:48.913" Score="4" Body="&lt;p&gt;My guess is that the manual trim wheel handle (when not motor driven) to adjust it manually needs to be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;easily accessible from the seat.&lt;/li&gt;&#xA;&lt;li&gt;generate a sufficient amount of torque by moment arm.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Which leaves this as one of the few spots where it could be conveniently placed. You can find the same thing in older aircraft cockpits including the L1011, B727 and B747-100/200. The 737 design remains very unchanged from when it first flew.&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-11-03T18:37:48.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22652" PostTypeId="2" ParentId="20722" CreationDate="2015-11-03T18:51:54.037" Score="2" Body="&lt;p&gt;The short answer is no. As you said in your question, the regulations you quoted require you to have logged &lt;em&gt;flight time&lt;/em&gt;, which is defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Flight time&lt;/em&gt; means:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Pilot time that commences when an aircraft moves under its own&#xA;  power for the purpose of flight and ends when the aircraft comes to&#xA;  rest after landing; or&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, you have to go fly a real aircraft. And 1.1 defines &quot;aircraft&quot; clearly too, so you can't argue that it includes simulators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even if you could use a simulator, you would still need an instructor present. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_151&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51&lt;/a&gt; talks about logging simulator time for various purposes, but in every case it also says that an &quot;authorized instructor&quot; must be present and endorse your logbook. That makes sense: if you're playing around by yourself in a simulator, you could be doing anything at all, including reinforcing your own bad habits. The instructor is there to ensure that what you're doing is useful and relevant, and you're learning from it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-11-03T18:51:54.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22653" PostTypeId="2" ParentId="22619" CreationDate="2015-11-03T19:19:13.363" Score="1" Body="&lt;p&gt;It could happen. &lt;a href=&quot;http://www.nrk.no/viten/fallskjermhopper-filmet-meteoritt-1.11628145&quot; rel=&quot;nofollow&quot;&gt;This lucky skydiver&lt;/a&gt; was only meters from a falling space rock, and got it on tape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Had he been an airplane (or a few meters longer) he &lt;em&gt;would&lt;/em&gt; have been hit!&lt;/p&gt;&#xA;" OwnerUserId="12117" LastActivityDate="2015-11-03T19:19:13.363" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22655" PostTypeId="2" ParentId="22619" CreationDate="2015-11-03T19:40:06.480" Score="1" Body="&lt;p&gt;I see that someone else did the math on the probability already, but I wanted to give some math with dimensions and numbers that might be more accurate, as well as give a comparison to other causes of plane crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At any point in time, there are about 10,000 commercial aircraft in the air, according to flight radar's metrics (although I'm not too sure how accurate those are). Assuming an average length of 50 meters, and a wingspan of 50 meters, and a hull and wing width of 8 meters, that's 800 m² per flying aircraft, and 8,000,000 m² for all planes combined, or about 8 km².&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a comment, someone pointed out that aircraft dimensions are actually closer to 200 m². The reason I chose math of 800 m² is because a direct impact is not the only way a meteor could affect an airborne craft. A sufficiently big meteor leaves behind a heat trail and a smoke trail. The heat trail causes local airflows to change, which could cause turbulence onboard passing aircraft. The smoke trail could theoretically damage the engines similar to how volcanic ash does, given that they're both ash and dust. If a layman is on an airplane affected by one of these incidents, it's understandable that they view this as &quot;being hit by a meteor&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How big is 8 km²? Well, that is comparable to the size of Greenbelt park in Staten Island, and about 2/3 the size of the Royal Borough of Kensington and Chelsea in London. I've tried finding reports of meteorites being found in that area, and while it is not impossible that one has landed there without anyone noticing, it is a very rare event. In fact, while there hasn't yet been a report of a plane crashing by a meteorite, a passenger killing both the captain and the copilot has been reported at least twice as the reason of a crash. I would personally be more worried about a mid-air impact of another plane, given that has happened enough by now to be featured multiple times on Mayday! (Air Crash Investigation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you only count direct impacts as actually hitting your aircraft, then assuming an average surface of 200 m² for a plane, and meteors only coming directly from above (since they can also come from the front, the sides or the back), there is a total surface size of about 2 km² when all aircraft are counted. This is a little smaller than the City of London (not the entirety of London, but the original inner city), or just over half the size of Central Park in New York.&lt;/p&gt;&#xA;" OwnerUserId="1823" LastEditorUserId="1823" LastEditDate="2015-11-04T17:29:56.193" LastActivityDate="2015-11-04T17:29:56.193" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="22656" PostTypeId="1" AcceptedAnswerId="22658" CreationDate="2015-11-03T20:52:18.717" Score="7" ViewCount="4030" Body="&lt;p&gt;I have heard about Special VFR many times but never understood this concept. What is it and when is it used?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-11-03T21:08:35.727" Title="What is Special VFR? Why would a pilot request it?" Tags="&lt;visual-flight-rules&gt;&lt;special-vfr&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-11-05T21:28:53.327" ContentLicense="CC BY-SA 3.0" />
  <row Id="22657" PostTypeId="2" ParentId="16800" CreationDate="2015-11-03T21:06:05.807" Score="2" Body="&lt;p&gt;Blade stop autos can be done with model helicopters, proving it is theoretically possible. There are a few differences in a model helicopters rotor design that make it more likely, but here is a video showing it done. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/ZnGvd1hpZs0?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; At 1:55 the blades are slowed to the point they are no longer spinning and the helicopter drops like a shot duck, until the operator reduces pitch enough to get them spinning again - without power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'd probably not be able to physically withstand the stresses, but I think it's technically possible. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-03T21:06:05.807" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22658" PostTypeId="2" ParentId="22656" CreationDate="2015-11-03T21:08:35.727" Score="10" Body="&lt;p&gt;Special VFR is used to leave or enter a control zone coming from or continuing the flight in airspace G (Golf), when the weather minima for VFR flight are not met within the control zone, but would be met in airspace G.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: Airspace G (Golf) requires a visibility of 1.5km and aircraft need to remain clear of clouds. Airspace D (Delta) requires a visibility of 5km and 1000ft vertical and 1.5km horizontal separation to clouds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the weather report would show a visibility of 4km/4000m and a cloud base of 1400ft, the flight would be allowed in airspace G but not in airspace D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Requesting Special VFR within a control zone will drop the VFR weather requirements to the values required for airspace G, so flight may enter or leave the controlzone. The lower visibility requirements are compensated for in the control zone by stricter separation requirements between aircraft. SVFR is separated to SVFR and IFR traffic.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-11-03T21:08:35.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22659" PostTypeId="2" ParentId="22619" CreationDate="2015-11-03T21:17:38.230" Score="5" Body="&lt;p&gt;OK, I've been asked to create a &quot;guesswork&quot; answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assumptions.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;75% of flights are made during daylight hours.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www2.le.ac.uk/departments/physics/research/xroa/astronomical-facilities-1/educational-guide/meteorites&quot; rel=&quot;nofollow&quot;&gt;75% of meteors occur at night&lt;/a&gt; for any given location and those meteorites are equally likely over half the worlds surface (probably about 25% overestimate).&lt;/li&gt;&#xA;&lt;li&gt;Aircraft distribution is uniform across the Earths surface (this will make my esimate incorrect by orders of magnitude since they are not, they are far more densely packed over the US, Europe and SE Asia)&lt;/li&gt;&#xA;&lt;li&gt;Number of aircraft in the air during the time when the 75% of meteors occur, &lt;a href=&quot;http://joannenova.com.au/2014/02/half-a-million-people-in-the-air-at-any-one-time/&quot; rel=&quot;nofollow&quot;&gt;2,500&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Average speed of meteorites, &lt;a href=&quot;http://www.amsmeteors.org/meteor-showers/meteor-faq/&quot; rel=&quot;nofollow&quot;&gt;80,000 mph&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Average surface area of aircraft, 300 m².&lt;/li&gt;&#xA;&lt;li&gt;If a meteor hasn't burnt out by 7 miles, it's not going to (it's a meteorite).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://curious.astro.cornell.edu/our-solar-system/75-our-solar-system/comets-meteors-and-asteroids/meteorites/313-how-many-meteorites-hit-earth-each-year-intermediate&quot; rel=&quot;nofollow&quot;&gt;350&lt;/a&gt; meteorites per day.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Ignoring the height for now.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total surface area of aircraft flying when the 75% of meteors fall. 750,000m².&lt;/p&gt;&#xA;&#xA;&lt;p&gt;% of Earth surface where the 75% fall covered with aircraft.  0.000003%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chance of any meteorite hitting the target surface area (an aircraft).  0.00105%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now factoring in height.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Depth of atmosphere where aircraft are found.  7 miles.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;An aircraft presents a target 150 feet high - big overestimate to account for the time the nose of the aircraft to the tail passes through the track of the meteorite.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ignoring that the meteorite will slow down as it passes through the atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Assuming a meteorite will pass where the aircraft will be, it spends 0.0036% of the time it falls at the height of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Multipyling the chance of it hitting the area described by the aircraft by the chance of it being at the same height in that area - 0.000000378% or about 4e-7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many people struggle to understand numbers that small.  To put it into perspective, the accepted chance of you being struck by lightning in your lifetime is 8e-5, or about 200 times as likely as an aircraft being hit by a meteorite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is so tiny that any one of my assumptions being wrong will make the number meaningless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safe to say, possible, but so unlikely as to be not even worth considering.  &lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-04T07:11:17.010" LastActivityDate="2015-11-04T07:11:17.010" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22660" PostTypeId="2" ParentId="10097" CreationDate="2015-11-03T21:39:40.240" Score="1" Body="&lt;p&gt;How do you taxi your plane? I use my engine to spin my propeller, which pulls on the hub and pulls my plane hard enough to make it roll on the ground. On takeoff, I do this so hard that the 2000+ lb plane rolls 60 knots or so before it leaves the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, with that in mind, do you think pulling on the prop, close to the hub, enough to move the plane 10 feet is doing any damage?&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-03T21:39:40.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22661" PostTypeId="2" ParentId="21612" CreationDate="2015-11-04T00:15:07.573" Score="8" Body="&lt;p&gt;There's no single, simple answer to this. As the FAA's &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7130.3A.pdf&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Holding Pattern Criteria&lt;/em&gt; order&lt;/a&gt; explains, they actually have 31 pre-defined sets of dimensions for different altitudes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;2-9.  SIZE AND NUMBERING.&lt;/strong&gt;   There are 31 holding airspace sizes.  Each is related to one or more even-numbered altitudes/flight levels&#xA;  and is identified by a template number for easy reference.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;2-10.  TEMPLATES-SCALING AND TRACING.&lt;/strong&gt;   Templates numbered to correspond with pattern numbers were developed in sectional chart&#xA;  scale (1:500,000) and should be used to determine protected holding&#xA;  airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems that a lot of variables were taken into account, as mentioned in &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs420/acfipg/media/closed/Hist_03-01-247.pdf&quot; rel=&quot;noreferrer&quot;&gt;this FAA commentary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;31 holding pattern templates  were developed to fit over 100 different&#xA;  combinations of indicated airspeed (IAS), altitude,  and distance from&#xA;  facility in the case of ground-based navaids.  Averaged seasonal winds&#xA;  aloft were part of this extensive 1964 evaluation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Chapter 2, Section 1 of the Order gives more details on those factors. The order also has instructions for making a template manually and it lists all the dimensions needed to define the protected airspace (see page 2-16, table 3). It's too much information to show here (and SE markup doesn't support tables) but there is a very wide range of values, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Template 1 has a total length of 11.6 nm and width of 6.7 nm&lt;/li&gt;&#xA;&lt;li&gt;Template 4 has 14.4 nm and 8.8 nm (as shown in &lt;a href=&quot;https://aviation.stackexchange.com/a/21571/62&quot;&gt;this answer&lt;/a&gt; to another question)&lt;/li&gt;&#xA;&lt;li&gt;Template 16 has 34.7 nm and 21.0 nm&lt;/li&gt;&#xA;&lt;li&gt;Template 31 has 84.9 nm and 57 nm&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The largest holding patterns are suitable for use where holding at higher then normal speeds is required; up to 280 kts.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-11-04T00:15:07.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22662" PostTypeId="1" AcceptedAnswerId="22663" CreationDate="2015-11-04T00:57:03.673" Score="4" ViewCount="387" Body="&lt;p&gt;As the title says, what conditions cause the gear-up warning to sound on a Bombardier DASH-8?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="22726" LastEditDate="2019-11-29T22:04:34.060" LastActivityDate="2019-11-29T22:04:34.060" Title="What conditions cause the gear-up warning to sound on a Bombardier DASH-8?" Tags="&lt;safety&gt;&lt;aircraft-systems&gt;&lt;emergency&gt;&lt;dash-8&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22663" PostTypeId="2" ParentId="22662" CreationDate="2015-11-04T01:14:56.800" Score="6" Body="&lt;p&gt;According to smartcockpit.com, warning is given when the gear has not been extended and the aircraft is in the landing configuration. Specifically,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;• All landing gear not down and locked, flaps selected to 15 or 35&lt;span class=&quot;math-container&quot;&gt;$^{\circ}$&lt;/span&gt;, and both power levers at any position less than 50% torque.&lt;/p&gt;&#xA;&lt;p&gt;• Landing gear not down and locked, one or both power levers at or near FLT IDLE and airspeed below 130 kts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The warning also sounds when the aircraft landing gear is up and terrain clearance is inadequate during the cruise and approach phase&#xA;of flight.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GQHyU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GQHyU.png&quot; alt=&quot;LG alert&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;em&gt;Dash8-200/300 - Warning Systems&lt;/em&gt; from smartcockpit.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-04T14:58:56.710" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22664" PostTypeId="2" ParentId="16108" CreationDate="2015-11-04T01:35:17.970" Score="0" Body="&lt;p&gt;There are four factors:  low airspeed less than 20 knots, partial power, high rate of descent greater than 300-500 feet/minute, and steep angle of descent greater than 30 degrees.  Somehow, the aircraft has to descend, either by settling or other means at great than 30 degrees.  Remove any of these four items and VRS is not possible.&lt;/p&gt;&#xA;" OwnerUserId="12122" LastActivityDate="2015-11-04T01:35:17.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22665" PostTypeId="1" AcceptedAnswerId="22667" CreationDate="2015-11-04T07:03:06.753" Score="8" ViewCount="3966" Body="&lt;p&gt;Which part of the aircraft contributes the highest portion of weight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: we had argument that, wires connecting the avionics systems are the major contributors of aircraft weight. Due to some issues with optical fibre technology this is not been used in aviation yet. So my question arises as mentioned above.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="3386" LastEditDate="2015-11-04T13:19:45.473" LastActivityDate="2019-11-09T16:57:59.890" Title="Which part of aircraft is contributing the most weight of airplane?" Tags="&lt;general-aviation&gt;&lt;aircraft-systems&gt;&lt;weight&gt;&lt;aircraft-subsystem&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22666" PostTypeId="2" ParentId="22640" CreationDate="2015-11-04T07:13:50.317" Score="2" Body="&lt;p&gt;There have been some great answers here with awesome information, but I don't think any of them address the premise of the question, which I believe to be incorrect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The premise is that it is ground effect that is creating a force keeping the car on the ground. This is not accurate. A race car sticks to the ground because it is designed to overcome ground effect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane in ground effect can still easily be flown into the ground with a sufficiently negative angle of attack, or from lack of lift due to wing stall. A car can be made to stick to the ground with suffient downforce - despite ground effect, not because of it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a sufficient flow of air is allowed under the car, with a positive angle of attack, it will absolutely experience the same exact ground effect as an airplane does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, an airplane can be driven all the way down the runway at cruise speeds without lifting off if you hold the elevator all the way in, though I wouldn't recommend doing that. Ground effect is not a magic levitation force, it simply reduces drag and it can easily be overcome. If not, landing would be impossible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bodywork of a race car is designed to overcome ground effect. The bottom of many race cars are also designed to maximize the advantage of low pressure, but this is not ground effect. This effect can be described anecdotally with the child's experiment of placing newspaper flat on a table on top a ruler, with the end of the ruler off the table, and then striking down on the ruler, which will break the ruler thanks to the air pressure on the top of the paper. When the car tries to lift off the road, the same force helps keep it stuck - but that force is not the &quot;ground effect&quot; that we refer to when flying an airplane close to the ground. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastEditorUserId="12116" LastEditDate="2015-11-04T07:23:37.313" LastActivityDate="2015-11-04T07:23:37.313" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22667" PostTypeId="2" ParentId="22665" CreationDate="2015-11-04T08:16:12.077" Score="17" Body="&lt;p&gt;&lt;a href=&quot;https://books.google.nl/books?id=8K6Y8MhqbKgC&amp;amp;pg=PA31&amp;amp;lpg=PA31&amp;amp;dq=aircraft%20component%20weight%20breakdown&amp;amp;source=bl&amp;amp;ots=sxuXIEbhVx&amp;amp;sig=HuRViKRNTpbIgNnqfkwjRCMQdQ0&amp;amp;hl=nl&amp;amp;sa=X&amp;amp;ved=0CCgQ6AEwAjgKahUKEwjCzY2OqPbIAhVI2xoKHZj9Cwc#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerospace Engineering e-Mega Reference&lt;/a&gt; shows the following table for two aircraft (the large commercial jet, the B747-100, and the military jet, the C-5A). You can see that it differs quite a lot between the B747 and the C-5 already, so it's hard to give a definitive answer for all aircraft in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it depends a lot on how you break down the components, for example, here the Nacelle and Propulsion system are shown separately, but if you combine the two (and some others as is done in the dry engine weight, I think) things could change. &#xA;The Aerospace Engineering e-Mega Reference points to &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770019162.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beltramo&lt;/a&gt; as the source for the numbers. Perhaps you could find some information there about what belongs to which group.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However for both aircraft, it can be seen that the Wing and the Airframe are significant contributors (and for the B747 furnishing is also a large part of the weight)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think they included all the wiring in the Avionics part (that would make sense to me), but still it is a relatively small part of the total weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dzXiC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dzXiC.jpg&quot; alt=&quot;Weight breakdown&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="20401" LastEditDate="2018-05-19T14:06:51.517" LastActivityDate="2018-05-19T14:06:51.517" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="22668" PostTypeId="2" ParentId="22619" CreationDate="2015-11-04T10:17:35.737" Score="1" Body="&lt;p&gt;This is, sadly, a highly topical question. There have been more than a few aircraft downings where a meteor impact has at least been considered so I think it is worth exploring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Acknowledgment: In the following calculations have gratefully borrowed figures from various contributors above.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First,&lt;/strong&gt; let's consider the question about traffic patterns:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Meteors mainly come from the direction Earth is travelling through space as it orbits the sun (effectively, the Earth &quot;runs them down&quot;).&lt;/li&gt;&#xA;&lt;li&gt;Meteors are in orbit around the sun before they hit Earth. So they are just as likely to come from inside the Earth's orbit (on the way out from the Sun) as from outside the Earth's orbit.&lt;/li&gt;&#xA;&lt;li&gt;This means they mostly occur between midnight and noon the next day. From noon to midnight, you're on the &quot;rear end&quot; of the Earth.&lt;/li&gt;&#xA;&lt;li&gt;I'm assuming traffic density between midnight and noon is roughly the same as between noon and midnight. This cancels out any effect of diurnal variation in traffic patterns. If you disagree with this point, divide the answer by two or three.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second,&lt;/strong&gt; I am going to integrate over a 24hr period to cancel out the variation in aircraft density as the &quot;front&quot; of the Earth moves round the planet (there are going to be more targets when Europe, North America and SE Asia are at the front than when it's dawn over the central Pacific Ocean).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third,&lt;/strong&gt; the aircraft speed is irrelevant. If a beetle is on a dartboard and you &lt;em&gt;randomly&lt;/em&gt; throw a dart, it doesn't matter if the beetle stays still or runs about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Now to the sums:&lt;/strong&gt; To be clear, I'm trying to work out the probability of &lt;em&gt;any&lt;/em&gt; meteor hitting &lt;em&gt;any&lt;/em&gt; aircraft in a 24 hour period. This is simply the area of the target divided by the total area presented by the Earth to the oncoming meteor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So: 10,000 planes in the air divided by 2 (only the leading half of the Earth is in target) $\times$ 300$m^2$ per plane divided by $\pi r^2$ for $r=6371km$ gives $1.2 \times 10^{-8}$. So one in a hundred million, roughly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, how many meteors &lt;em&gt;that could down a plane&lt;/em&gt;, hit the Earth per day? Planes are pretty fragile - I'm going to guess that a 0.2m bolide (bowling ball?) if it hit the plane anywhere, would definitely do it. &lt;a href=&quot;http://www.geert.io/the-frequency-of-large-meteoroids.html&quot; rel=&quot;nofollow&quot; title=&quot;One reference above&quot;&gt;One reference above&lt;/a&gt; says there are about 2000 of these per year. So 5 per day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That gives a final probability that &lt;em&gt;any&lt;/em&gt; plane is downed by any meteor in &lt;em&gt;any&lt;/em&gt; 24 hour period of $6 \times 10^{-8}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the rate is about &lt;strong&gt;once every 40,000 years&lt;/strong&gt;, or so. Yeah... probably not worth bothering about.&lt;/p&gt;&#xA;" OwnerUserId="9189" LastActivityDate="2015-11-04T10:17:35.737" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22669" PostTypeId="1" AcceptedAnswerId="22670" CreationDate="2015-11-04T10:35:55.687" Score="2" ViewCount="311" Body="&lt;p&gt;I vaguely remember when younger a spotter I knew having a book listing all airlines and all aircrafts within the airline at time of print. Is this data available now in book or online format? I'm looking to get back into spotting.&lt;/p&gt;&#xA;" OwnerUserId="3355" LastEditorUserId="167" LastEditDate="2015-11-05T04:15:56.803" LastActivityDate="2015-11-05T04:15:56.803" Title="How can I find aircraft and airline listing data for planespotting?" Tags="&lt;plane-spotting&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22670" PostTypeId="2" ParentId="22669" CreationDate="2015-11-04T11:05:49.243" Score="2" Body="&lt;p&gt;You can find much of this sort of information at &lt;a href=&quot;http://www.airfleets.net&quot; rel=&quot;nofollow&quot;&gt;http://www.airfleets.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, searching for &lt;a href=&quot;http://www.airfleets.net/flottecie/British%20Airways.htm&quot; rel=&quot;nofollow&quot;&gt;British Airways&lt;/a&gt; lists their fleet, and clicking the number of active for a model (eg &lt;a href=&quot;http://www.airfleets.net/flottecie/British%20Airways-active-a318.htm&quot; rel=&quot;nofollow&quot;&gt;A318&lt;/a&gt;) will list the tail number and other interesting information. From there you can click a &lt;a href=&quot;http://www.airfleets.net/ficheapp/plane-a318-4007.htm&quot; rel=&quot;nofollow&quot;&gt;specific airplane&lt;/a&gt; for all the information along with a picture.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-11-04T11:05:49.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22671" PostTypeId="2" ParentId="22669" CreationDate="2015-11-04T11:46:57.727" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.airfleets.net&quot; rel=&quot;nofollow&quot;&gt;airfleets.net&lt;/a&gt; has details of aircraft with most airlines online and also in &lt;a href=&quot;http://www.airfleets.net/shop/product.htm&quot; rel=&quot;nofollow&quot;&gt;paper and ebook&lt;/a&gt; formats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft data is also available with &lt;a href=&quot;https://www.planespotters.net/airlines&quot; rel=&quot;nofollow&quot;&gt;planespotters.net&lt;/a&gt; and also with &lt;a href=&quot;http://www.flightradar24.com/data/airplanes/&quot; rel=&quot;nofollow&quot;&gt;flightradar24.com&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-04T11:46:57.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22672" PostTypeId="2" ParentId="22665" CreationDate="2015-11-04T16:04:11.980" Score="-4" Body="&lt;p&gt;If you mean by part of aircraft it will be the landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if you mean what other stuff add weight you have the electronic entertainment system that adds alot of wires and cables which add weight to the airplane but with no operational use for the airline its only to entertain passengers.&lt;/p&gt;&#xA;" OwnerUserId="12097" LastActivityDate="2015-11-04T16:04:11.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22673" PostTypeId="2" ParentId="22669" CreationDate="2015-11-04T16:44:07.833" Score="1" Body="&lt;p&gt;You may wish to try &lt;a href=&quot;http://www.planelogger.com&quot; rel=&quot;nofollow&quot;&gt;PlaneLogger&lt;/a&gt;, which is an online site for logging your aircraft sightings. It has a large database similar to AirFleets, but allows you to mark off the aircraft as you seen them.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastActivityDate="2015-11-04T16:44:07.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22675" PostTypeId="1" CreationDate="2015-11-04T17:14:10.330" Score="2" ViewCount="1404" Body="&lt;p&gt;I am currently 26, female and making financial arrangements to pursue a cpl after 2 years. The location probably will be Canada or USA. I am wondering if 29 is too late for commercial airlines. Do the airlines prefer younger pilots? Is there a max age limit for commercial airlines?&#xA;Thanks for the help.&#xA;Cheers,&#xA;Litali&lt;/p&gt;&#xA;" OwnerUserId="12130" LastEditorUserId="11787" LastEditDate="2015-11-04T17:37:28.133" LastActivityDate="2016-07-11T15:59:04.360" Title="Do airlines prefer younger pilots after a cpl?" Tags="&lt;commercial-aviation&gt;&lt;airlines&gt;&lt;cpl&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-11-04T18:32:10.840" ContentLicense="CC BY-SA 3.0" />
  <row Id="22676" PostTypeId="2" ParentId="22675" CreationDate="2015-11-04T18:22:28.817" Score="10" Body="&lt;p&gt;29 is not too late for them. It might be too late for you, depending on where you are in your life now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off, a CPL won't cut it to fly for most Part 121 or Part 135 outfits, including major airlines, cargo haulers etc. As of 2013, the requirements to get on the flight deck of a commercial airliner include an ATPL, which requires a minimum of 1500 hours (1000 if you attend a four-year flight school). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A CPL, with instrument rating and an endorsement to ferry passengers for hire, would allow you to fly for a company like NetJets, or for a corporate or government jet fleet, though you'll face stiff competition for those jobs; they're fairly cushy and well-paid for the required experience, and you'll find a lot of ex-military and ex-airline pilots beating down the door. You'd also be able to fly foreign-registered aircraft for a non-US airline, as long as the jurisdiction hasn't adopted a similar rule as the FAA's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you get your ATPL, with only the 1500 hours and no other airline experience, you'll likely land your first gig as First Officer on a regional route. This is your toehold into a career in flying, and to be perfectly honest if you don't absolutely love to fly I would tell you to do &lt;em&gt;anything&lt;/em&gt; else, especially if you've already started a life (married, kids, mortgage). The average starting salary for a regional FO is about \$22,500 per year, which for a 40 hour work week is a meager \$10.75 an hour. You would literally make more working full-time as a barista in Sea-Tac Airport serving coffee to the pilots than flying the puddle-jump between there and Portland. And that's just the average; you can expect half the currently flying pilots with less than 1 year experience to make less than that. You are virtually guaranteed to make more money doing &lt;em&gt;anything else&lt;/em&gt; that requires more than a high school diploma.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It gets better, but it takes a career to do it. Senior captains flying the big widebodies on major transcontinental and intercontinental routes make six figures, in excess of \$175k in some cases. Most of this is the airlines trying to retain their most experienced pilots for just a little longer by giving them the most profitable routes for which they can pay the pilots more. The other part is making up for the peanuts they pay you in your early years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the majority of your career, your entire life will fit in a carryon and/or a garment bag; flying regionals, you'll make the same flight five to ten times a day and have a good chance to get back to your home city, but on regional pay you'll be hard-pressed to afford more than a single-bedroom flat. As your experience grows, your promotions will naturally lead to longer flights on bigger jets, with the best-paying routes being intercontinental flights where you'll sleep on the plane two nights out of three. Many pilots have month-to-month arrangements with their landlords to rent a single room to crash in and store anything that doesn't fit in their flight bag. This will be your life for 20-30 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is extremely common for newly retired pilots and their spouses to invest in a &quot;pilot's house&quot;; while most retirees are downsizing from the house they raised kids in, most pilots are finally able to settle down in one location for the first time in their lives, and are buying McMansions in cash at about that same age, with savings from the last few years of their flying career.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, flying sounds like a glamorous, &quot;see the world&quot; job, but you have to be &lt;em&gt;sure&lt;/em&gt; you can live with the downsides. Your spouse will essentially be a single parent (if you have kids), you'll be living in a small apartment for most of your life and will move several times, requiring your spouse to have a career that allows easy relocation, and you might only be home every other day if not less often, depending on the airline's scheduling model; it's fairly common especially among LCCs to run &quot;end-to-end&quot; routes instead of &quot;hub and spoke&quot;, and that could mean you'll start in New York, run hops through Chicago, Atlanta and Dallas with your eight hours allowable flight time per day, then sleep in Dallas and fly the reverse route the next day back to New York.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to make a direct comparison, my wife has a cosmetology license (haircuts, nails, spa treatments) in Texas. To get that license required a 2-year course of study and 1500 hours total instruction and guided practice. Her first year with that license, she made about $33000, almost 50% more than a first-year airline pilot. The economics of the airline industry (and the regulations in the cosmetology industry) are bass-ackwards.&lt;/p&gt;&#xA;" OwnerUserId="7629" LastEditorUserId="7629" LastEditDate="2016-07-11T15:59:04.360" LastActivityDate="2016-07-11T15:59:04.360" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22677" PostTypeId="1" AcceptedAnswerId="22683" CreationDate="2015-11-04T19:12:27.087" Score="4" ViewCount="751" Body="&lt;p&gt;I'm trying to answer the following question, but I'm not sure of which one is correct.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A glider is gliding with constant angle of attack along its path. We can assume the hypothesis of small angles. Under these conditions, the following has to be fulfilled:&lt;/p&gt;&#xA;&lt;p&gt;a) None of the other answers is correct.&lt;/p&gt;&#xA;&lt;p&gt;b) &lt;span class=&quot;math-container&quot;&gt;$C_L=C_{Lopt}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;c) &lt;span class=&quot;math-container&quot;&gt;$\hat{D} =$&lt;/span&gt; constant&lt;/p&gt;&#xA;&lt;p&gt;d) &lt;span class=&quot;math-container&quot;&gt;$\alpha=\alpha_{max}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;e) V must remain constant&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; D with hat means dimensionless drag.&lt;/p&gt;&#xA;&lt;p&gt;I've been trying to discard some of them but I'm still doubting about if the correct answer is (a) or (e). Can you help me guess which one is the right one?&lt;/p&gt;&#xA;" OwnerUserId="4358" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-12T13:43:25.483" Title="Which of these is true for a glider flying with constant angle of attack?" Tags="&lt;glider&gt;&lt;aircraft-physics&gt;&lt;angle-of-attack&gt;&lt;flight-dynamics&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22678" PostTypeId="1" AcceptedAnswerId="22686" CreationDate="2015-11-04T20:29:28.813" Score="25" ViewCount="14937" Body="&lt;p&gt;I've seen several instructional videos on crosswind landing techniques.  Some advise the pilot to crab the aircraft until just before touchdown when he/she should kick the rudder over to align the aircraft with the runway centerline.  Others advise the pilot to slip the aircraft all the way down so that no other cross control maneuver is needed.  Many of these videos also acknowledge the other way of doing things but say that their method is superior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an accepted &quot;safer&quot; method for flying a final approach with a crosswind or is it an entirely personal preference?&lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2019-03-29T19:47:07.397" Title="On crosswind landings, is it preferable to side slip or crab on final approach?" Tags="&lt;landing&gt;&lt;crosswind&gt;" AnswerCount="7" CommentCount="6" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22679" PostTypeId="2" ParentId="22678" CreationDate="2015-11-04T21:06:09.357" Score="3" Body="&lt;p&gt;This comes down to situation and personal preference. I am more preferential to the crabbed approach as that is how I was taught and that is what I am comfortable with. If you are talking strictly from a safety point one could argue that what ever method you are more proficient and comfortable in is &quot;safer&quot;. With a slipped approach you are coming in along the runway path so you will most likely not need much last second correction. A crabbed approach will require some adjustments close to touch down but like any landing you should be on full attention.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a technical stand point, a slipped approach puts the plane in &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight&quot; rel=&quot;nofollow&quot;&gt;uncoordinated flight&lt;/a&gt; which can be viewed as inefficient. Slipping also increases drag that you will need to compensate for with power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also find that I prefer to crab in really gusty or high wind situations to keep the plane a bit more stable on final. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-04T21:06:09.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22680" PostTypeId="1" AcceptedAnswerId="22689" CreationDate="2015-11-04T21:14:28.783" Score="10" ViewCount="2653" Body="&lt;p&gt;In the aircraft cockpits I've seen, the gear handles all seem to have the same general shape (they look like a little wheel). Is there a reason for this beyond simply making it absolutely obvious that it's the gear handle?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2015-11-05T16:51:58.540" Title="Why is the gear handle shaped the way it is?" Tags="&lt;aircraft-design&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22681" PostTypeId="2" ParentId="22678" CreationDate="2015-11-04T21:34:34.793" Score="3" Body="&lt;p&gt;I up voted Dave's answer, but mine is the same but opposite. I learned to slip all the way down final, and I prefer it, but I think it depends, like was mentioned in the other answer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to slip because it aides in bleeding off speed, I don't have to upset the controls of the aircraft at the last minute, and I'm keeping the upwind wing down throughout the final, minimizing the chance of a gust lifting the wing up unexpectedly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it depends on the aircraft, pilot, and situation, but I'm comfortable with the slip and that's what matters to me. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastEditorUserId="755" LastEditDate="2015-11-05T06:09:57.427" LastActivityDate="2015-11-05T06:09:57.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22682" PostTypeId="2" ParentId="22680" CreationDate="2015-11-04T21:36:30.947" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;making it absolutely obvious that it's the gear handle&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the very reason. Cockpit ergonomics are not only to make things easy to use but easy to tell apart. &lt;a href=&quot;http://generalaviationnews.com/2015/04/10/pilot-mistakes-gear-handle-for-flap-lever/&quot; rel=&quot;noreferrer&quot;&gt;Here is an incident&lt;/a&gt; in a smaller plane as a result of flap handle/gear handle confusion. Here is an &lt;a href=&quot;http://libraryonline.erau.edu/online-full-text/ntsb/special-investigation-reports/SIR80-01.pdf&quot; rel=&quot;noreferrer&quot;&gt;NTSB report&lt;/a&gt; on the same issue with Beech Bonanza &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If memory serves this also happened on a bigger plane once (im trying to find the accident report).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There has also been a push to make cockpits at least similar across the board to avoid issues. The best example of this issue has been the difference between American and Russian made attitude indicators which offer the visual appearance of being reversed of each other. You can &lt;a href=&quot;http://www.iasa.com.au/folders/Safety_Issues/dfdr-cvr/avionics-flashair.html?AID=/20060128/NEWS01/601280501&quot; rel=&quot;noreferrer&quot;&gt;read about that here&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why there is specifically a little wheel on the lever you can &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/147082/&quot; rel=&quot;noreferrer&quot;&gt;check out this discussion&lt;/a&gt; over on airliners.net about that very topic. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-04T21:52:31.880" LastActivityDate="2015-11-04T21:52:31.880" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22683" PostTypeId="2" ParentId="22677" CreationDate="2015-11-04T21:44:30.083" Score="8" Body="&lt;p&gt;Two things are important here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is about a glider, so no fuel is consumed, and the mass is constant over time.&lt;/li&gt;&#xA;&lt;li&gt;The angle of attack is constant. This means also that the lift and drag coefficients are constant.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the mass and the lift coefficient are constant, and we assume a constant load factor (implied by the &lt;code&gt;gliding along its path&lt;/code&gt; description), the dynamic pressure is also constant, and the airspeed changes with the square root of air density. &lt;code&gt;Gliding&lt;/code&gt; implies that the altitude decreases, so the &lt;strong&gt;indicated&lt;/strong&gt; speed will be constant, but the &lt;strong&gt;true&lt;/strong&gt; speed will decrease. Unfortunately, the condition e) is not precise enough to make this distinction. e) could be correct or not, depending on the definition of V.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would suggest that also c) could be a correct answer: If the angle of attack and the mass are constant, so should be the drag coefficient. However, gliding down also implies that the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7533/why-simple-paper-planes-fly-better-than-most-realistic-paper-plane-models/7536#7536&quot;&gt;Reynolds number&lt;/a&gt; changes because true speed decreases and temperature increases over the glide. Strictly speaking, this would also mean a very slowly changing drag coefficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answers b) and d) are false and I agree with your reasoning.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-11-04T21:44:30.083" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22684" PostTypeId="1" AcceptedAnswerId="22688" CreationDate="2015-11-04T21:50:03.280" Score="8" ViewCount="1864" Body="&lt;p&gt;If I understand correctly, there are two way to connect a tug: with or without a bar; and the tug can push back or pull forward the airliner.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When using a bar, how is the tug connected to the airliner? Is there a standardized fixation? Is there any articulation on both sides of the bar?&lt;/li&gt;&#xA;&lt;li&gt;When using a towbarless tug, the tug lift the nose wheel. How is it done? Is there limitation on nose-wheel dimensions?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3394" LastActivityDate="2019-12-17T17:40:43.290" Title="How is the pushback tug connected to the airliner?" Tags="&lt;pushback&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22685" PostTypeId="1" CreationDate="2015-11-04T22:11:37.857" Score="7" ViewCount="381" Body="&lt;p&gt;Sitting on the plane yesterday, wanting some fresh air and boom it hit me [literally]. What would happen, let's say both static and mid flight, if everyone turned on there air vents at the same time? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could the unit handle all of it simultaneously, would it effect pressure, I'm not privy to the working of air units of aircraft so it may be a silly question but it's still a question that I'm interested in knowing the answer to. &lt;/p&gt;&#xA;" OwnerUserId="12134" LastActivityDate="2015-11-05T12:05:58.817" Title="What would happen if you turn on all air vents simultaneously?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22686" PostTypeId="2" ParentId="22678" CreationDate="2015-11-04T22:22:28.383" Score="56" Body="&lt;p&gt;Neither technique is &amp;quot;preferable&amp;quot; - the assumption that one is superior to the other is one of the most common &lt;a href=&quot;https://yourlogicalfallacyis.com/black-or-white&quot; rel=&quot;noreferrer&quot;&gt;false dichotomies&lt;/a&gt; (and over-simplifications) in aviation.&lt;/p&gt;&#xA;&lt;p&gt;With some notable exceptions (like the Ercoupe which is incapable of a slip and lands crabbed) a proper crosswind landing should involve elements of &lt;em&gt;both&lt;/em&gt; techniques.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Crabbing&lt;/h1&gt;&#xA;&lt;p&gt;Crabbing involves turning the nose into the wind so that some component of the aircraft's &lt;em&gt;thrust&lt;/em&gt; is counteracting the crosswind, allowing the aircraft's ground track to align with the runway.&lt;/p&gt;&#xA;&lt;h2&gt;Advantages&lt;/h2&gt;&#xA;&lt;p&gt;Flying on final it is advantageous to crab into the wind: It is aerodynamically more favorable than a slip, and as the aircraft is kept coordinated it is more comfortable for passengers than a slip.&lt;br /&gt;&#xA;Pilots often find a crab subjectively &amp;quot;easier&amp;quot; to maintain for extended periods of time compared to a slip: It does not require the pilot to maintain &amp;quot;crossed controls&amp;quot;, and it's similar to how we maintain our course in other phases of flight (you were probably crabbing into the wind on downwind just a few seconds ago, and on instrument approaches flying the localizer in a crab is analogous to tracking a VOR on the enroute portion of your flight).&lt;/p&gt;&#xA;&lt;h2&gt;Disadvantages&lt;/h2&gt;&#xA;&lt;p&gt;On touchdown however landing in a crab will put a side-load on the landing gear (the aircraft is traveling along the runway centerline, but the gear is not aligned with that direction of travel). In extreme cases this can damage the tires, cause difficulty controlling the aircraft, and possibly even damage the landing gear assembly itself.&lt;br /&gt;&#xA;&amp;quot;Kicking out the crab&amp;quot; to align the landing gear with the runway requires an abrupt control movement at low altitude (generally not a good thing), and if done too early the crosswind will begin to blow the aircraft across the runway (leading to a landing that's not on the centerline, a side-load on the gear, and in the worst case an unintended departure from the runway surface.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Slipping&lt;/h1&gt;&#xA;&lt;p&gt;Slipping involves banking the aircraft so that some portion of the wing's &lt;em&gt;lift&lt;/em&gt; is counteracting the crosswind. Ordinarily the aircraft would tend to turn in the direction of the bank, so opposite rudder is applied to prevent the aircraft from turning and maintain the ground track parallel to the runway.&lt;/p&gt;&#xA;&lt;h2&gt;Advantages&lt;/h2&gt;&#xA;&lt;p&gt;Touching down on the runway a slip has the advantage of allowing you to align your landing gear with your direction of travel (down the runway) and avoid side-loading the gear. It also allows you to touch down on the upwind landing gear first which helps to stabilize the early roll-out, and positions your ailerons appropriately for taxiing with the crosswind.&lt;/p&gt;&#xA;&lt;h2&gt;Disadvantages&lt;/h2&gt;&#xA;&lt;p&gt;Slipping down final however is likely to make your passengers uncomfortable - the plane is slanted in one direction, the rudder is pushing the nose around in the other direction, and folks start to feel like their butt is sliding out of the seat.&lt;br /&gt;&#xA;Aside from passenger comfort a slip is a terribly inefficient aerodynamic arrangement (you're essentially trying to fly sideways), and not a &amp;quot;normal&amp;quot; way to fly in other phases of flight. You may have difficulty estimating the aircraft's performance and require power to maintain your glide path in this configuration.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Combining the techniques&lt;/h1&gt;&#xA;&lt;p&gt;So a crab is advantageous on final (and flying an instrument approach), and a slip is advantageous on touchdown. It logically follows that the two techniques can be combined to provide the advantages of both:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Crab down final (or on the localizer).&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;At some point transition into a slip.&lt;/strong&gt;&lt;br /&gt;&#xA;Exactly where you make this transition is pilot preference, but the transition should be smooth, simultaneously bringing the nose around to align with the runway while banking into the wind to counteract the crosswind component.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Touch down in the slip.&lt;/strong&gt;&lt;br /&gt;&#xA;Complete your rollout with the appropriate crosswind aileron deflection, controlling your ground track with the rudder as needed to prevent weathervaning.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-04T22:22:28.383" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22687" PostTypeId="2" ParentId="22677" CreationDate="2015-11-04T22:45:26.973" Score="5" Body="&lt;p&gt;Constant angle of attack implies a constant C&lt;sub&gt;D&lt;/sub&gt; and constant C&lt;sub&gt;L&lt;/sub&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that the aircraft is a glider implies a constant mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;'along its path'  does not imply that the path angle is constant. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a phugoid motion, the flight path angle is oscillating and so are the speed and the load factor, but the AoA is constant (by approximation).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can assume the aircraft is in a phugoid motion with low amplitude and/or long period, so that the hypothesis of small angles is valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose the dimensionless drag is constant during the phugoid motion even though both velocity and load factor are constantly changing. They cancel each other out. The fact the dimensionless drag coefficient C&lt;sub&gt;D&lt;/sub&gt; is constant is also a hint here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My  answer would be 'c'&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-11-08T15:07:59.883" LastActivityDate="2015-11-08T15:07:59.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22688" PostTypeId="2" ParentId="22684" CreationDate="2015-11-04T23:34:49.670" Score="15" Body="&lt;p&gt;You're correct that there are two ways to connect the tug with an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case a tow bar is used, it is fixed laterally at the nose landing gear, while allowing slight movement for height adjustment. Usually, the tow bar may pivot freely laterally and vertically at the end that attaches to the tug rather than the aircraft end, which is fixed. The following image shows the tow bar attachment point in Airbus A380.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GlTOo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GlTOo.jpg&quot; alt=&quot;A380 nose wheel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from alamy.com.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The attachment points differ from aircraft to aircraft, so the tow bar basically operates as an adapter between the aircraft and the tug.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uTxs4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uTxs4.jpg&quot; alt=&quot;Tow bars&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Pins_for_pushback.jpg#/media/File:Pins_for_pushback.jpg&quot; rel=&quot;noreferrer&quot;&gt;Pins for pushback&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When using a towbarless tug, the nose wheel is simply scooped off the ground using hydraulic (for large aircraft) or electric power. The tug has a movable arm, which is opened and the tug is moved and placed so that the nose wheel fits inside the fixed arms of the tug. The movable arm is then closed. The movable arm and the opposite side has sloping edges, over which the wheels slide and the nose is lifted off as the arm closes due to hydraulic power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This video shows how its done in case of Airbus A380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/8nopHgXojb8?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Video from Youtube: &lt;em&gt;How to lift up the world's largest commercial aircraft the Airbus A380.&lt;/em&gt; by user Kasavubu &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose wheel dimensions and aircraft weight do matter and tugs are certified for different ramp weights.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3825" LastEditDate="2015-11-05T00:07:32.920" LastActivityDate="2015-11-05T00:07:32.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22689" PostTypeId="2" ParentId="22680" CreationDate="2015-11-04T23:50:44.103" Score="8" Body="&lt;p&gt;It's required by law, at least in the US. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?n=pt14.1.23#se14.1.23_1781&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 23.781&lt;/a&gt;, &lt;em&gt;Cockpit control knob shape&lt;/em&gt; specifies these shapes for the flap and gear controls on smaller aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OkmUZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OkmUZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For larger (transport category) aircraft, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=7c0ae31610f1718f67b6c73e76269310&amp;amp;mc=true&amp;amp;node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1781&quot; rel=&quot;nofollow noreferrer&quot;&gt;25.781&lt;/a&gt; specifies the same thing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mvtKu.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mvtKu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for &lt;em&gt;why&lt;/em&gt; those shapes are specified, it's for at least two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The shape resembles the thing it controls, so it's an obvious memory aid&lt;/li&gt;&#xA;&lt;li&gt;The controls are all shaped differently, therefore you can distinguish them by touch alone, without needing to look at them&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As others &lt;a href=&quot;https://aviation.stackexchange.com/a/22682/62&quot;&gt;have noted&lt;/a&gt;, there have been accidents in the past caused by pilots using the wrong controls, and this is one reason why the FAA decided to do something to standardize them. Parts 23 and 25 also state &lt;em&gt;where&lt;/em&gt; the controls should be placed, for the same reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA's &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-2of7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane Handbook&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There have been many cases of the pilot mistakenly grasping the wrong&#xA;  handle and retracting the landing gear, instead of the flaps, due to&#xA;  improper division of attention while the airplane was moving.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They recommend - and I was taught - leaving the flaps alone after landing until clear of the runway (unless you have a good reason for retracting them earlier, like a short-field landing), then check and retract them with the statement &quot;flaps &lt;em&gt;identified&lt;/em&gt; and retracted&quot;. &quot;Identified&quot; in this case simply means that you're sure you have the right control in your hand. Some instructors even avoid touch-and-goes in complex aircraft (i.e. with retractable gear) because they feel the risk of retracting the gear rather than the flaps during the maneuver is too high; they stop and go instead, even if that means taxiing back for takeoff.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-05T16:51:58.540" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22690" PostTypeId="2" ParentId="22685" CreationDate="2015-11-05T00:02:37.610" Score="10" Body="&lt;p&gt;@Casey is correct. Nothing will happen under normal operating conditions. The FAR §25.831 Ventilation requires,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the ventilation system must be designed to provide each occupant with an airflow containing at least 0.55 pounds of fresh air per minute.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general, the amount of air available is far greater than the requirement. On the ground, compressed air for the Environmental Control System, which supplies air to crew and passengers can be obtained from an APU, a GCU, airport high-pressure hydrants, or the aircraft engines. In flight, however, compressed air is obtained almost exclusively from the compressor stages of the aircraft engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure would not be affected by this. According to FAR §25.843, Tests for pressurized cabins, the pressurized cabins are tested to show the performance of&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the pressure supply, pressure and flow regulators, indicators, and warning signals, in steady and stepped climbs and descents at rates corresponding to the maximum attainable within the operating limitations of the airplane, up to the maximum altitude for which certification is requested. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that in some aircraft the air conditioning system is switched off during climb- this is to do with the load on engine and not the air supply.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-05T00:02:37.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22691" PostTypeId="2" ParentId="22640" CreationDate="2015-11-05T00:12:54.253" Score="1" Body="&lt;p&gt;I think there is a lot of great information in the answers here but they miss the obvious. It's about the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a wing angled to point downwards close to the ground will not generate lift - it will create a lower pressure under/behind the wing (as well as a greater pressure above) and &quot;suck&quot; (and push) it down into the ground. And that is what is desired and designed with cars.&lt;/p&gt;&#xA;" OwnerUserId="12135" LastActivityDate="2015-11-05T00:12:54.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22692" PostTypeId="1" AcceptedAnswerId="44292" CreationDate="2015-11-05T03:20:39.560" Score="6" ViewCount="354" Body="&lt;p&gt;An uncommanded reverser unstow at high power is quite a problematic event for a flightcrew to handle, at minimum.  As a result, engine and airframe builders put protection mechanisms in to prevent this -- such as auto-restow functions, and on the CFM56-5, code in the FADEC that automatically rolls back the engine to idle upon detecting an uncommanded unstow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I have not seen any documentation for the A320 family with IAE V2500 series engines that details what the FADECs on those engines do in case of an uncommanded unstow of the reversers.  (The A320 FCOM on Smartcockpit only covers the CFM56-5 equipped versions of the A320 family.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone fill me in on this?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2017-10-02T12:47:40.960" Title="On the V2533 engine, what protections do the FADECs provide against uncommanded unstow?" Tags="&lt;safety&gt;&lt;engine&gt;&lt;airbus-a320&gt;&lt;thrust-reverser&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22693" PostTypeId="2" ParentId="22678" CreationDate="2015-11-05T05:27:01.613" Score="6" Body="&lt;p&gt;It seems airbus recommends a crab:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;IV Final Approach Technique Figure 1  shows that  depending on the recommendations  published in  the aircraftoperating manual, the final approach under  crosswind conditions may be conducted:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With  wings-level  (i.e., applying a drift correction in  order to track the runway centerline,  this type of  approach  is called a crabbed approach  [Airbus recommended technique]),&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With a  steady sideslip  (i.e.,  with the aircraft fuselage aligned with  the runway centerline,  using a combination  of  into-wind  aileron  and opposite  rudder to  correct the drift).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Airframe manufacturers  consider the following factors  when recommending a wingslevel or a steady-side-slip approach:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft geometry (i.e.,  pitch attitude  and bank  angle limits for preventing tail  strike, engine nacelle contact or  wingtip contact)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ailerons (roll)  and rudder (yaw) authority&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Crosswind  component.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;This Flight  Operations  Briefing  Note  focus on  the  wings-level /  crabbed approach technique,  recommended by Airbus, to discuss the associated flare and decrab techniques  depending on  the crosswind component.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;From&lt;/em&gt; AirbusFlight Operations Briefing Note, Landing Techniques, Crosswind Landings &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-LAND-SEQ05.pdf&quot; rel=&quot;noreferrer&quot;&gt;pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-05T05:27:01.613" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22694" PostTypeId="1" CreationDate="2015-11-05T08:26:25.953" Score="6" ViewCount="3285" Body="&lt;p&gt;I am unsure on how to solve this problem. The only clue i have is to integrate ROC to find time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet aircraft has the capacity to fly at an absolute altitude ceiling of 11000 m,&#xA;and a rate of climb (ROC) at sea level of 20.87 m/s. Calculate the time to climb&#xA;from sea level to 8000 m. Assume a linear variation of the rate of climb with&#xA;altitude during the whole maneuver.&lt;/p&gt;&#xA;" OwnerUserId="12138" LastEditorUserId="19" LastEditDate="2017-08-14T08:03:48.303" LastActivityDate="2017-08-14T14:13:12.300" Title="How to find total climbing time based on Rate of Climb?" Tags="&lt;aircraft-performance&gt;&lt;altitude&gt;&lt;climb&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22695" PostTypeId="2" ParentId="22694" CreationDate="2015-11-05T08:43:14.070" Score="6" Body="&lt;p&gt;The fastest way is an integration. If you plot the inverted climb speed over altitude like in the plot below, the area under the curve will give you the time to climb. I would suggest you calculate the climb speed at every 1000&amp;nbsp;m by rule of proportion — at sea level it is 20.87&amp;nbsp;m/s and at 11.000&amp;nbsp;m it is 0&amp;nbsp;m/s. Then you get a plot like the one below. The red circles are the calculated points; the lines between them are straight interpolations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the unit on the Y-axis is seconds per meter and the unit on the X-axis is meters, the area is in seconds. Just calculate the area of each trapezoid between the start and the end altitudes and add them. In the figure below I have crosshatched the trapezoids between 3000&amp;nbsp;m and 8000&amp;nbsp;m. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2wtdH.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2wtdH.png&quot; alt=&quot;Inverted climb speed over altitude&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inverted climb speed over altitude plot. Caution — this is a generic plot I did for this purpose earlier, so it uses different numbers. I crosshatched the area between 3000&amp;nbsp;m and 8000&amp;nbsp;m, because I made the plot for calculating the climb time from 3000&amp;nbsp;m to 8000&amp;nbsp;m.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="2143" LastEditDate="2015-11-05T14:09:25.217" LastActivityDate="2015-11-05T14:09:25.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22697" PostTypeId="1" CreationDate="2015-11-05T10:33:11.657" Score="0" ViewCount="483" Body="&lt;p&gt;While booking tickets for a commercial airliner, is it possible to know the name of the aircraft (not the model, but the designated name) and then search the history of the plane, on how old is it, how many repairs has it gone through, has it ever had an accident etc.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1696" LastEditDate="2015-11-05T15:38:36.083" LastActivityDate="2015-11-05T15:38:36.083" Title="How do I find a plane's history when booking a flight?" Tags="&lt;airlines&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22698" PostTypeId="2" ParentId="22697" CreationDate="2015-11-05T11:17:46.513" Score="7" Body="&lt;p&gt;Unless you are booking at the very last minute, no there is no way to find out which particular aircraft you'll be on until you're strapped in. The airline themselves plan in advance but as soon as one plane needs unexpected maintenance, or is excessively delayed, the schedule is thrown out the window. For this reason more than anything no airline to my knowledge publishes this schedule. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you are at the gate you might be able to see the aircraft registration. If you google that you can see if it has been in any serious incidents, when it was delivered and how old it is. You won't be able to find out how many repairs it has gone through, only the airline has that (hint: the answer could be hundreds of times if you're counting minor issues). &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-11-05T11:17:46.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22699" PostTypeId="2" ParentId="22685" CreationDate="2015-11-05T12:05:58.817" Score="4" Body="&lt;p&gt;To add to @aeroalias' excellent answer: compressed outside air (whether from the engines or separate compressors) is fed into the plane's air conditioning system, from where it's distributed to the cabin, the cockpit, etc. The air destined for the cabin is routed to air outlets (sometimes called diffusers), installed above and/or below the hatracks (&lt;a href=&quot;https://aviation.stackexchange.com/a/1675/1478&quot;&gt;picture&lt;/a&gt; - look for some long, thin openings near the hatracks next time you fly), which blow the air into the cabin. Air is blown into the cabin to control the temperature in the cabin and to ensure a constant supply of fresh air for the passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air gaspers (what you call &quot;air vents&quot;) above the passengers are (usually) connected to the same ducts which feed the air outlets, which means that when you open a gasper, a tiny amount of the air which would normally enter the cabin through an air outlet enters it through the open gasper instead. Therefore, even if everyone opened their gaspers, the total amount of air going to the cabin wouldn't change - except that some of it would be routed via the gaspers instead of the &quot;normal&quot; air outlets. However, even in this case, the majority of the air would still be routed to the air outlets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note that when I say &quot;routed&quot;, it's all done passively via the design of the air conditioning ducts and manifolds; there is no &quot;active&quot; routing (via valves or suchlike) between the air outlets and the gaspers.)&lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-11-05T12:05:58.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22700" PostTypeId="1" CreationDate="2015-11-05T13:16:57.913" Score="1" ViewCount="599" Body="&lt;p&gt;Are there any studies that have researched into fear of flying when not in the cockpit? The question arises from the fact that for some reason, I have found myself to be scared when on a plane as a passenger, but when at the commands the situation is totally different. This applies also to a lot of people when driving cars for example. Is this a normal human behaviour?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="62" LastEditDate="2015-11-05T14:36:44.990" LastActivityDate="2015-11-09T00:22:47.800" Title="Is it normal to be scared of flying before becoming a pilot?" Tags="&lt;pilots&gt;&lt;medical&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22701" PostTypeId="2" ParentId="22662" CreationDate="2015-11-05T15:19:54.183" Score="3" Body="&lt;p&gt;To further elaborate on aeroalias' answer, &quot;terrain clearance inadequate&quot; is determined by the radar altimeter.  If the radar altimeter returns an altitude lower than the threshold and the gear is not extended, the warning will sound.  &lt;/p&gt;&#xA;" OwnerUserId="7752" LastActivityDate="2015-11-05T15:19:54.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22702" PostTypeId="2" ParentId="21620" CreationDate="2015-11-05T16:05:32.810" Score="-3" Body="&lt;p&gt;I'm not sure, but I think that those are trim tabs.&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2015-11-05T16:05:32.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22703" PostTypeId="2" ParentId="21620" CreationDate="2015-11-05T16:31:39.207" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/q/7955/1696&quot;&gt;anti-shock bodies&lt;/a&gt; also serve as fairings for the flap actuators. When the flaps are extended, the anti-shock bodies move down as the flap mechanisms extend. The upper surfaces of the anti-shock bodies are open to allow room for these mechanisms to extend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extensions to the flaps are to cover the openings of the anti-shock bodies when the flaps are retracted to provide a more aerodynamic surface. Evidently the outer locations have larger openings to cover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is an image of a different aircraft and flap track design, but the principle is the same. You can see some of the hardware that sits in the fairings, and the covers that allow the hardware to extend out of the fairings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O2PS2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O2PS2.jpg&quot; alt=&quot;Anti-shock bodies showing flap mechanisms&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sub&gt;&lt;a href=&quot;http://img850.imageshack.us/img850/448/13316294.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the flaps are retracted, you can see that the flaps close out the top of the anti-shock bodies, and the outer position is closed out further aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wHGiL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wHGiL.jpg&quot; alt=&quot;A320 wing, flaps retracted&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sub&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f4/Wing-a320.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-11-05T16:46:07.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22704" PostTypeId="2" ParentId="22678" CreationDate="2015-11-05T17:44:01.413" Score="3" Body="&lt;p&gt;To answer this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depend on what are you flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my side as an airbus pilot we are trained always to approach with a crab then at the flare we de crab and allign the nose with the runway centerline using rudder.&lt;/p&gt;&#xA;" OwnerUserId="12097" LastActivityDate="2015-11-05T17:44:01.413" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22705" PostTypeId="2" ParentId="22684" CreationDate="2015-11-05T17:57:07.237" Score="5" Body="&lt;p&gt;As mentioned there are two ways used for pushback: towbar and towbarless (TBL) push trucks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a third way that is not as common: the Power Push Unit (PPU).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/82hKT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/82hKT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://www.airliners.net/photo/Virgin-Blue-Airlines/Boeing-737-81Q/1025594&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike the standard pushback process that uses a pushback truck and a towbar attached to the nose wheel, the PPU is a remote controlled truck directly attached to one of the main landing gear bogies. It pushes the aircraft backwards and the pilot steers the nose wheel based on the instructions of the PPU operator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on &lt;a href=&quot;http://extranet2.terbergdts.co.uk/showbestand.php?Id=279&amp;amp;Checksum=b2ef6448&quot; rel=&quot;nofollow noreferrer&quot;&gt;one company&lt;/a&gt;, the way it works is via &quot;pressure rollers [that] grip the tyres. Rotational friction forces drive the aircraft's wheels.&quot;&lt;/p&gt;&#xA;" OwnerUserId="12097" LastEditorUserId="14897" LastEditDate="2019-12-17T17:40:43.290" LastActivityDate="2019-12-17T17:40:43.290" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="22707" PostTypeId="1" CreationDate="2015-11-05T19:40:23.550" Score="3" ViewCount="5545" Body="&lt;p&gt;So occasionally I will be flying my rc helicopter and I turn it left to right (rudder) but see nothing moving on the helicopter. On an aircraft there is a vertical stabilizer that has a moving rudder. So how does a helicopter work? The same thing occurs with my quadcopter. &lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="595" LastEditDate="2015-11-05T19:58:56.257" LastActivityDate="2015-11-05T23:21:13.783" Title="How does a helicopter rudder work?" Tags="&lt;helicopter&gt;&lt;rudder&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22708" PostTypeId="2" ParentId="22707" CreationDate="2015-11-05T19:46:41.963" Score="4" Body="&lt;p&gt;Helicopters do not have rudders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=wc9TDIPR3uU&quot; rel=&quot;nofollow noreferrer&quot;&gt;They have tail rotors.&lt;/a&gt;  You yaw left and right by varying the pitch of the blades, therefore varying the thrust they generate to counter the torque from the main rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Helicopter_rotor&quot; rel=&quot;nofollow noreferrer&quot;&gt;From Wikipedia.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oLvCR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oLvCR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helicopters use &lt;a href=&quot;https://www.youtube.com/watch?v=q9NPDFGeC6I&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;NOTAR&quot; (NO TAil Rotor) or ducted fans&lt;/a&gt;.  The duct is rotated with the anti-torque pedals which varies the horizontal component of the thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZlOvE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZlOvE.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.quadcopterflyers.com/2015/02/quadcopters-yaw-roll-and-pitch-defined.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Quadcopters yaw by changing the speed&lt;/a&gt;, and therefore the thrust, of the rotors individually to &quot;bend&quot; the quadcopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vEBd4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vEBd4.png&quot; alt=&quot;From the UAV society blog&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://uav-society.blogspot.co.uk/2014/06/quadcopter-mechanics.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://uav-society.blogspot.co.uk/2014/06/quadcopter-mechanics.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-05T19:56:04.437" LastActivityDate="2015-11-05T19:56:04.437" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22710" PostTypeId="1" AcceptedAnswerId="22712" CreationDate="2015-11-05T21:39:19.400" Score="18" ViewCount="4001" Body="&lt;p&gt;Are there any aircraft that can mechanically modify the dihedral angle of the wings whilst in flight? Would this solution give any advantage?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-11-05T22:24:46.643" LastActivityDate="2015-11-06T20:35:43.527" Title="Can any aircraft adjust the wing dihedral in flight?" Tags="&lt;wing&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22711" PostTypeId="2" ParentId="22678" CreationDate="2015-11-05T22:22:28.970" Score="4" Body="&lt;p&gt;I was taught the same way as Hmb.  Although the larger Part 121 planes must touch down pretty level to avoid dragging an engine or a wing, they fly crabbed until short final.  I was told that this is for passenger comfort as flying un-coordinated can make some squeamish pax a bit green.  So for me, it is crab and kick - fly the approach crabbed and kick out the crab before you touch down.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2015-11-05T22:22:28.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22712" PostTypeId="2" ParentId="22710" CreationDate="2015-11-05T22:37:38.563" Score="35" Body="&lt;p&gt;There was one, and it did it to increase directional stability at supersonic speed. I am talking of the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;North American XB-70&lt;/a&gt;, of course. There were three benefits to this configuration:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Improved directional stability. Without the effect of the folded-down wingtips, the XB-70 would had lost all directional stability upwards of Mach 2. The wingtips folded down to 64.5° anhedral (or is it -64.5° dihedral?) which effectively made them into ventral fins. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5239/would-a-vertical-stabilizer-that-extends-both-above-and-below-the-centerline-be/5242#5242&quot;&gt;This answer&lt;/a&gt; explains how a ventral fin is especially helpful at supersonic speed, because it works in the compressed air below the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Less shifting of the aerodynamic center. Since the transition to supersonic flight will shift the aerodynamic center back, folding the wing tips down reduces lift in the aft section of the wing, thus reducing the aftward shift.&lt;/li&gt;&#xA;&lt;li&gt;Better capture of the compressed lower wing flow for lift creation, which is called a &lt;a href=&quot;https://en.wikipedia.org/wiki/WaveRider&quot; rel=&quot;noreferrer&quot;&gt;waverider&lt;/a&gt;. This increases the pressure on the lower side of the wing at high supersonic speed and allows to fly with a reduced angle of attack, thus reducing drag.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FyUsP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FyUsP.jpg&quot; alt=&quot;XB-70 landing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XB-70 landing with wingtips straight (picture &lt;a href=&quot;http://i.kinja-img.com/gawker-media/image/upload/zrzh0oykie7im6555fdg.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Axop.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Axop.jpg&quot; alt=&quot;XB-70 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XB-70 in flight with wingtips down (picture &lt;a href=&quot;http://www2.interceptor.com/~thumper/xb2/in-flight.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The XB-70 is also one of only a few types where every aircraft ever built had different dihedral: AV-1, the first prototype, had 0° while AV-2, the second prototype, had 5° dihedral over the whole wing to improve yaw and roll stability. Only the dihedral of the outer panels could be adjusted in flight, however. According to &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/XB70PresS07.pdf&quot; rel=&quot;noreferrer&quot;&gt;this source (PDF!)&lt;/a&gt; they were the largest moveable aerodynamic device ever used on an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other cases of variable dihedral were less intentional, though, and there was really no advantage to it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gkNfM.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gkNfM.png&quot; alt=&quot;F-4 with wingtips folded up&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like on many Navy aircraft, the wings of the F-4 could be folded for stowage. If the mechanism was not locked, the wings would fold up. The F-4 was even powerful enough to be flyable this way. When only one side folded up, &lt;a href=&quot;http://luckypuppy.net/i-watched-as-the-phantom-crashed/&quot; rel=&quot;noreferrer&quot;&gt;the F-4 would crash&lt;/a&gt;, however.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-11-06T20:35:43.527" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22713" PostTypeId="2" ParentId="22707" CreationDate="2015-11-05T23:21:13.783" Score="7" Body="&lt;p&gt;In helicopter, the yaw control is usually obtained by adjusting the pitch of the tail rotor, that changes the 'thrust' produced by the tail rotor; this rotates the helicopter about its yaw axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FiUyv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FiUyv.jpg&quot; alt=&quot;Helicopter Yaw&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: cfidarren.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of helicopters without a tail rotor, the yaw control is obtained in different ways. The NOTAR used a method similar to the tail rotor, by varying the thrust. In case of tandem rotors (like Chinook) , the yaw control is obtained by differential lateral cyclic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XXHYP.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XXHYP.gif&quot; alt=&quot;Tandem rotor yaw&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: tech-mp.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The quadcopters obtain yaw control by adjsuting the speed of the rotors. In quadcopter, two rotors (say 1 and 3) rotate in one direction, while the other two (2 and 4) move in the other. By slowing down 1 and 3 while speeding up 2 and 4, you can make the quadicopter yaw to the left. The torque of 2 and 4 spinning to the right makes the body spin to the left. Conversely, by slowing down 2 and 4 while speeding up 1 and 3, the quadcopter yaws to the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s89vw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s89vw.jpg&quot; alt=&quot;Quadcopter Yaw&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: safaribooksonline.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of coaxial helicopters like the Kamon Ka-25, the yaw control is obtained by varying the torques (i.e. by varying the pitch) of both the main rotors simultaneously in opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SBO4h.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SBO4h.gif&quot; alt=&quot;Coaxial yaw&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: simhq.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coaxial helicopters (like Kamov Ka-25) do have movable rudders like aircraft for use in forward flight as it reduces the main rotor adjustment required and is more effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qkmOX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qkmOX.jpg&quot; alt=&quot;Helicopter rudder&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ka-25 rudder, image from travelforaircraft.wordpress.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image below shows the control methods used in different types of helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4XAuD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4XAuD.jpg&quot; alt=&quot;Helicopter controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from unicopter.com, credited to Rotary-Wing Aerodynamics.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-05T23:21:13.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22714" PostTypeId="2" ParentId="22710" CreationDate="2015-11-05T23:49:32.390" Score="18" Body="&lt;p&gt;In general, any aircraft will have its dihedral modified in flight due to the aerodynamic loads, though it is more pronounced in case of aircraft having high aspect ratio and slender wings like the Boeing 787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TrRJM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TrRJM.jpg&quot; alt=&quot;Boeing 787 wing flex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from stackexchange.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The North American XB-70 had a wing tip which was foldable in flight, which helped trap the shock wave under the wing between the downturned wing tips, creating compression lift, and also improved directional stability at high speeds by adding more vertical surface to the aircraft and reducing the rearward shift of aerodynamic center.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/47Oup.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/47Oup.gif&quot; alt=&quot;XB 70&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:XB-70_final_proposal.gif#/media/File:XB-70_final_proposal.gif&quot; rel=&quot;noreferrer&quot;&gt;XB-70 final proposal&lt;/a&gt;&quot; by NASA - NASA CR-115703, Volume 2, page 23.Transferred from&amp;nbsp;en.wikipedia&amp;nbsp;to Commons&amp;nbsp;by&amp;nbsp;&lt;a href=&quot;//commons.wikimedia.org/wiki/User:TheDJ&quot; rel=&quot;noreferrer&quot; title=&quot;User:TheDJ&quot;&gt;TheDJ&lt;/a&gt;&amp;nbsp;using CommonsHelper.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Ornithopters vary their dihedral all the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rfNl0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rfNl0.jpg&quot; alt=&quot;Ornithopter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ornithopter built by University of Toronto School of aerospace technologies; image from philschophoto.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-06T00:01:57.210" LastActivityDate="2015-11-06T00:01:57.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22715" PostTypeId="2" ParentId="22700" CreationDate="2015-11-06T00:02:14.780" Score="6" Body="&lt;p&gt;I think its extremely normal. The fear of the unknown is very powerful. When you are in control, you generally know what is coming and aren't surprised. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most pilots I know have no desire to sky dive. They love the freedom of flying, but falling uncontrolled is not enjoyable to them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I'm not PIC, sudden drops give me that put in the stomach feeling. When I'm in control, that NEVER happens. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-06T00:02:14.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22716" PostTypeId="2" ParentId="16296" CreationDate="2015-11-06T06:07:26.033" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/foqG5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/foqG5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a couple of oil flow visualization pictures.  Presumably they are taken at the same Mach number and lift coefficient. The left hand picture appears to show the upper surface of the wing with flow separation where the shock meets the surface.  The airfoil sections probably pre-date supercritical designs.  The right hand picture shows the application of Kuchemann carrots (or Whitcomb fairings). The flow appears to be shockless.  &lt;a href=&quot;https://i.stack.imgur.com/Sycmd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sycmd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lower picture shows application of these fairings to the Convair 990.  I think I'm right in saying that supercritical airfoil sections, which are designed to weaken the shock, eliminate the benefit of these fairings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not clear to me that the flap track fairings on the A380 (and many other aircraft) have the same (or similar) effect seeing as the flow on the lower surface of the wing is subcritical at just about all operating conditions, as Peter Kampf points out. His analysis implies that the benefit is not due to transonic area ruling, but to other aerodynamic effects, and I'm sure he is correct.&lt;/p&gt;&#xA;" OwnerUserId="12147" LastActivityDate="2015-11-06T06:07:26.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22719" PostTypeId="1" AcceptedAnswerId="22720" CreationDate="2015-11-06T07:59:51.907" Score="15" ViewCount="12480" Body="&lt;p&gt;&lt;a href=&quot;https://web.archive.org/web/20191231060539/http://fat.gfycat.com/HilariousMassiveBighornedsheep.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://web.archive.org/web/20191231060539/http://fat.gfycat.com/HilariousMassiveBighornedsheep.gif&quot; alt=&quot;&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://fat.gfycat.com/HilariousMassiveBighornedsheep.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://fat.gfycat.com/&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The aircraft in this GIF (although being an RC plane) seems to be flying vertically, just meters above the ground. How is this possible? How is it possible to control it in this scenario? Would this be possible with a real aircraft?&lt;/p&gt;&#xA;" OwnerUserId="12150" LastEditorUserId="8282" LastEditDate="2021-01-15T21:37:10.400" LastActivityDate="2021-02-04T20:07:01.477" Title="How can an aircraft hover almost vertically?" Tags="&lt;aircraft-performance&gt;&lt;fighter&gt;&lt;aerobatics&gt;&lt;maneuver&gt;&lt;model-aircraft&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="22720" PostTypeId="2" ParentId="22719" CreationDate="2015-11-06T08:12:53.293" Score="16" Body="&lt;p&gt;The aircraft in the video is a remote-controlled (rc) airplane. Why it can &amp;quot;hover&amp;quot; is simply:&lt;/p&gt;&#xA;&lt;p&gt;The thrust generated by a big fan / rc-jet-engine is much higher than the weight of the plane.&#xA;If the force generated by the turbine is the same as the downward-force of weight of the airplane, it hovers.&#xA;By very carefully adjusting the thrust and placing the aircraft in this &amp;quot;nose-up&amp;quot; position, a skilled rc-pilot can hover the plane until the battery runs out or fuel gets low.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MumJY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MumJY.png&quot; alt=&quot;Force explained&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As example:&#xA;An aircraft that weights 10,000 kg's produces a downforce:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$F=m\cdot g=10,000 \cdot  9.81  = 98,100N $$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;To make this aircraft hover, you have to create a upward force of at least &lt;span class=&quot;math-container&quot;&gt;$98,100 N$&lt;/span&gt;. If you manage to do that and you can align the generated thrust / downforce perfectly on the Y-Axis, the aircraft will hover:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$F_{down} - F_{up} = 0N$&lt;/span&gt;, the two forces will cancel each other out and you don't have any movement in the Y-Axis.&lt;/p&gt;&#xA;&lt;p&gt;However, if you have engines that create more thrust than the downforce, the following will happen:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$F_{down} - F_{up} \geq 0N$&lt;/span&gt;, that means the aircraft will climb vertically (On the Y-Axis).&lt;/p&gt;&#xA;&lt;p&gt;The same principle applies to other &amp;quot;real&amp;quot; aircraft, like the Sea-Harrier:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZYtct.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZYtct.jpg&quot; alt=&quot;Sea Harrier hover&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;It uses the engine to create a force facing upwards. Because the force is greater than the downward-force created by the aircrafts weight, the Harrier can land / takeoff vertically.&lt;/p&gt;&#xA;&lt;p&gt;The hovering airctaft is controlled by a trust-vectoring fan / turbine. Controlling the plane with the &amp;quot;normal&amp;quot; surfaces is not possible, because the airflow over the controll-surfaces on the wing is to slow. Therefore, only planes with trust-vectoring capabilities COULD hover like the rc-plane in your question.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="3499" LastEditDate="2021-02-04T20:07:01.477" LastActivityDate="2021-02-04T20:07:01.477" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="22721" PostTypeId="2" ParentId="22719" CreationDate="2015-11-06T08:29:43.837" Score="-1" Body="&lt;p&gt;Its an rc basically you have more power more thrust and the airplane body is light as paper so u can hover with thrust and control with normal control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In real aircraft its hard.&lt;/p&gt;&#xA;" OwnerUserId="12097" LastActivityDate="2015-11-06T08:29:43.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22722" PostTypeId="1" AcceptedAnswerId="22723" CreationDate="2015-11-06T09:07:58.107" Score="15" ViewCount="3376" Body="&lt;p&gt;According to the &lt;a href=&quot;http://timesofindia.indiatimes.com/world/middle-east/Watch-Two-men-with-Jetman-wings-fly-alongside-an-Emirates-A380-plane-4000-feet-above-Dubai/articleshow/49684855.cms&quot; rel=&quot;nofollow noreferrer&quot;&gt;Times of India&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Yves Rossy and Vincent Reffet - have achieved the rare feat of flying with the innovative Jetman wings, on either side of an Emirates A380 aircraft, the world's largest passenger aircraft, 4000 feet above sea level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My Questions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is flying near other aircraft is legal?&lt;/li&gt;&#xA;&lt;li&gt;How they avoid getting into jet turbulence and other forces?&lt;/li&gt;&#xA;&lt;li&gt;Is there Jetman suit available to catch up to the jet engined planes?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gyuNT.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gyuNT.png&quot; alt=&quot;Jet Man Flying above an A380&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="5517" LastEditDate="2015-11-09T14:29:50.330" LastActivityDate="2015-11-09T14:29:50.330" Title="Is Jetman flying above other aircraft allowed? How it is possible?" Tags="&lt;safety&gt;&lt;jet&gt;&lt;flying-in-formation&gt;" AnswerCount="2" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="22723" PostTypeId="2" ParentId="22722" CreationDate="2015-11-06T09:15:17.247" Score="25" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes.  This is part of a series of promotional stunts, &quot;adverts&quot;, Emirates are undertaking.  Aircraft can fly in formation, all other rules taken into account, if the captains agree.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By flying above the aircraft.  As the article states, it was meticulously planned for safety (after all, an accident would be disatrous PR), and the Jetman flyers would know exactly where not to go.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yes.  The video shows that!  The aircraft will likely be flying at slow speed.  As you can see, the flaps are extended.  I'm guessing about 160 kts.  I would also imagine the flyers will have dived down from above to pick up speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-11-06T09:15:17.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22724" PostTypeId="1" AcceptedAnswerId="22725" CreationDate="2015-11-06T10:04:14.993" Score="2" ViewCount="776" Body="&lt;p&gt;Can the ILS be manually turned off? Not by the pilots inside the cockpit by simply shutting of the ILS button, but rather by a 3rd party personnel, such as an ATC or a ground crew member. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC shuts off ILS on RWY 05L for safety reasons.. or traffic separation reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I am a second year electronics and communications student, so if you would like to use a couple of technical terms, i can understand them, to some extent&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="12151" LastEditorUserId="9544" LastEditDate="2015-11-06T13:34:57.160" LastActivityDate="2015-11-06T13:44:55.330" Title="Can the ILS be shut down?" Tags="&lt;ils&gt;&lt;localizer&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2015-11-12T09:02:28.217" ContentLicense="CC BY-SA 3.0" />
  <row Id="22725" PostTypeId="2" ParentId="22724" CreationDate="2015-11-06T10:49:19.840" Score="3" Body="&lt;p&gt;The ILS, or precisely the components localizer and glidepath antennas can be shut off, as they are electronic devices that emit radio signals. They can be turned off and on by ATC where required, e.g. having the same ILS frequency for two opposite runways and you only want one to be active at the same time or they can be shut down by maintenance directly at the emitters. ILS are usually not powered by UPS, so they will not be available during power outages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If equipment is being shut down for maintenance or other reasons, you will see this mentioned in the &lt;a href=&quot;https://en.wikipedia.org/wiki/NOTAM&quot; rel=&quot;nofollow&quot;&gt;NOTAM&lt;/a&gt;, such as here from Cologne/Bonn Airport, where the glidepath portion of the ILS runway 24 is out of service:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A4932/15 - ILS GP RWY 24 OUT OF SERVICE. 01 OCT 00:00 2015 UNTIL 30 DEC 00:00 2015 ESTIMATED. &#xA;CREATED: 27 AUG 13:34 2015 &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://notaminfo.com/explain?id=485741/0&quot; rel=&quot;nofollow&quot;&gt;NOTAM EDDK&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2015-11-06T13:44:55.330" LastActivityDate="2015-11-06T13:44:55.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22726" PostTypeId="2" ParentId="22724" CreationDate="2015-11-06T11:19:41.887" Score="3" Body="&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, shutting down the ILS means shutting down the localizer and glideslope signals. There is more than one reason to 'shut down' the ILS. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ILS is designed to shut down automatically on detection of fault. FOr example, if the primary transmitter (of glideslope) malfunctions, the system will automatically transfer to the standby transmitter. If that fails or if the standby transmitter also malfunctions, the system automatically will shut down, with ATC being automatically informed. Cat III ILS systems are required to shut down within 2 seconds of fault detection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA carries out &lt;a href=&quot;http://www.ainonline.com/aviation-news/aviation-international-news/2008-04-23/faa-flight-check-operations&quot; rel=&quot;nofollow&quot;&gt;flight check operations&lt;/a&gt; on various navigational aids in airports and can require the ATC to shut down the ILS if error is more than limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ILS can be shut down because of equipment change, maintenance etc. Of course, if the power goes out, &lt;a href=&quot;http://abcnews.go.com/US/landings-aborted-north-carolina-airport-dark-warning/story?id=25773860&quot; rel=&quot;nofollow&quot;&gt;ILS goes out with it&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per regulations, any shutdown of ILS (or any other navaid) is to be informed via NOTAM.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-06T11:19:41.887" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22728" PostTypeId="2" ParentId="22722" CreationDate="2015-11-06T12:14:00.713" Score="5" Body="&lt;p&gt;To answer the third questions about how they caught up with the A380: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Jetmen currently fly with a 140 kg high-tech carbon-fiber wing which is fitted with 4 Jetcat P400 engines. The engines are powered by a mix of kerosene and turbine oil capable of pushing a combined thrust of 160kg. This allows us to cover a distance of approximately 40km with speeds of up to 140 – 170 knots.&lt;br&gt;&#xA;  &lt;sup&gt;Source: &lt;a href=&quot;https://www.facebook.com/jetmanofficial/&quot; rel=&quot;nofollow&quot;&gt;Jetman Facebook page&lt;/a&gt; and &lt;a href=&quot;https://www.facebook.com/jetmandubai/&quot; rel=&quot;nofollow&quot;&gt;Jetman Dubai Facebook page&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The A380 approach category is cat (c) the approach speed with flaps should be anything from 121 to 141 knots. &lt;/p&gt;&#xA;" OwnerUserId="12097" LastEditorUserId="5517" LastEditDate="2015-11-09T14:21:25.317" LastActivityDate="2015-11-09T14:21:25.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22729" PostTypeId="1" AcceptedAnswerId="22743" CreationDate="2015-11-06T12:27:55.360" Score="46" ViewCount="14130" Body="&lt;p&gt;Looking at this picture of an A380 cockpit I see that there are still a lot of traditional switches (meaning manual click on and off or knobs). Being technology so advanced in these days, why is it that traditional switches and knobs are used instead of having a couple of touch screens on which the various controls are placed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't this make it more economic as there would be savings on material and wiring? They could also be less susceptible to failures as traditional switches and knobs still rely on mechanical actions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage I could think of is that every pilot could customise positioning of controls and switches based on his/her way of piloting. This could then be reset to a default state every time a new pilot takes over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GJOcz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GJOcz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="3394" LastEditDate="2015-11-06T13:30:08.007" LastActivityDate="2017-06-01T20:14:56.007" Title="Why are traditional knobs not replaced by touchscreens in cockpits?" Tags="&lt;cockpit&gt;&lt;glass-cockpit&gt;" AnswerCount="10" CommentCount="25" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22730" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T12:37:11.183" Score="22" Body="&lt;p&gt;Mechanical switches gives a better visual inspection than digital touch screens. For a pilot surrounded with so many switches, just a visual glance would be enough to find the position of the control.&lt;/p&gt;&#xA;" OwnerUserId="11916" LastActivityDate="2015-11-06T12:37:11.183" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22731" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T12:46:29.870" Score="15" Body="&lt;p&gt;Beyond the obvious aviation reasons of cost and so on, I can think of a few reasons why I'd not want an over reliance on touchscreens in the cockpit:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;If a touchscreen fails, you've lost all the controls that were related to it.&lt;/li&gt;&#xA;&lt;li&gt;Likewise, if a touchscreen (or portion of) fails then the whole thing has to be replaced rather than just the button&lt;/li&gt;&#xA;&lt;li&gt;Feedback - phones and similar devices offer things like haptic feedback to register a positive touch. I can't imagine that being implemented and working well in a fixed monitor. Pressing a button provides a positive reinforcement that you did press the button.&lt;/li&gt;&#xA;&lt;li&gt;Using touch-screens is hard if they're not still - it's far easier to press a physical button, without pressing an adjacent button, than it is to press an area on a screen without accidentally glancing another area.&lt;/li&gt;&#xA;&lt;li&gt;Some controls are designed to be easy to operate, while being hard to do accidentally - for example flaps, gears, mixture etc. All of these require some positive force.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With that said - you've posted some advantages and, in honesty, I suspect it'll all happen one day. So, for that reason, in the meantime I give you the stock answer to any &quot;Why isn't...&quot; aviation question:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Cost&lt;/li&gt;&#xA;&lt;li&gt;Certification&lt;/li&gt;&#xA;&lt;li&gt;Proven reliability&lt;/li&gt;&#xA;&lt;li&gt;Market demand&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Unless pilots and airliners are crying out for it, and a manufacturers think it will make the difference between whether they buy a particular aircraft or not, they simply aren't going to spend the time and money necessary to make it a reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, it'll almost certainly come in slowly. It's one thing to add some touch functionality to a flight computer but I wouldn't be expecting flap and gear levers to be touch sensitive anytime soon!&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-11-06T12:46:29.870" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22732" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T12:51:44.263" Score="57" Body="&lt;p&gt;Adding to the absolutely correct answer of @Mach1:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flicking a switch gives clear haptic and audible feedback. Compare that to a touchscreen where you can never be sure if your intention has been interpreted correctly. This might not seem to matter much, but if you need to throw 20 switches in a hurry, the mechanical solution is head and shoulders above anything with a touch input.&lt;/li&gt;&#xA;&lt;li&gt;Mechanical switches can be operated with gloves on. Touchscreens generally cannot.&lt;/li&gt;&#xA;&lt;li&gt;If the computer driving the touchscreen crashes, you are out of control. Mechanical switches don't have this failure mode.&lt;/li&gt;&#xA;&lt;li&gt;Mechanical switches are far easier to debug than touchscreens. You can make sure if the switch works by using a screwdriver and a voltmeter. And some knowledge of the routing, admittedly.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;@Greg Taylor and @Lightsider are correct: Inadvertently flicking a mechanical switch is so much harder than one on a touchscreen, especially if it has a cage to protect it from movements in an off direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t4GyD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t4GyD.jpg&quot; alt=&quot;Toggle switch with cage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Toggle switch with cage (picture &lt;a href=&quot;https://i2.wp.com/static1.businessinsider.com/image/551440d2eab8ea4d547ed7fc-1200-750/rtr4uzqb.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-06-01T20:14:56.007" LastActivityDate="2017-06-01T20:14:56.007" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="22733" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T12:56:46.610" Score="8" Body="&lt;p&gt;Touchscreen flight displays are already under production and the first commercial aircraft with touch screen primary flight displays as standard equipment to receive FAA certification is the Beechcraft King Air 250 turboprop equipped with Rockwell Collins Pro Line Fusion avionics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some issues with touchscreen, &lt;a href=&quot;https://www.thalesgroup.com/en/worldwide/aerospace/magazine/touchscreens-cockpit-pure-hype-or-genuinely-helpful&quot;&gt;such as&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...special security procedures are needed to avoid unintentional taps or movements that could jeopardise flight safety, especially during turbulence.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, touch screens for aircraft are under intense development by almost all of the major avionics manufacturers and should be available for large aircraft by the end of the decade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aside, the F-35 is the first combat aircraft to use a touch screen.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-06T12:56:46.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22734" PostTypeId="1" AcceptedAnswerId="22742" CreationDate="2015-11-06T14:20:21.163" Score="6" ViewCount="1212" Body="&lt;p&gt;Before examining this XB-70 picture &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/en/thumb/8/8a/North_American_XB-70A_Valkyrie_Ser._No_62-0001.jpg/1200px-North_American_XB-70A_Valkyrie_Ser._No_62-0001.jpg&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/en/thumb/8/8a/North_American_XB-70A_Valkyrie_Ser._No_62-0001.jpg/1200px-North_American_XB-70A_Valkyrie_Ser._No_62-0001.jpg&quot; alt=&quot;North_American_XB-70A_Valkyrie&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought that all canard were one single flight control surface (as seen on many fighters such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/File:RAF_Eurofighter_Typhoon_cockpit.jpg&quot; rel=&quot;nofollow&quot;&gt;Eurofighter Typhoon&lt;/a&gt;), and that there functionning were comparable to &lt;a href=&quot;https://en.wikipedia.org/wiki/File:RAF_Eurofighter_Typhoon_cockpit.jpg&quot; rel=&quot;nofollow&quot;&gt;stabilators&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the XB-70 exhibit something that looks like large flaps at the trailing edge of its canard. Apparently, it is not the only airplane with this feature (e.g. the &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Saab_AJS-37_Viggen_37098_52_%28SE-DXN%29_%289256079273%29.jpg&quot; rel=&quot;nofollow&quot;&gt;Saab 37 Viggen&lt;/a&gt; is also equipped with similar canard).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this canard flap? How does it work? Is there any pro/cons of this configuration compared to a all moving canard (I don't know if this can be called stabilator as this is not located on the tail)?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="5517" LastEditDate="2015-11-06T16:35:54.473" LastActivityDate="2015-11-06T16:38:07.990" Title="How do canard flaps work?" Tags="&lt;control-surfaces&gt;&lt;canard&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22736" PostTypeId="2" ParentId="22710" CreationDate="2015-11-06T15:39:00.853" Score="6" Body="&lt;p&gt;Hang-gliders are an obvious answer.  For over 30 years, all higher-performance hang-gliders have had a pull-cord to tighten/loosen the sail, variously called &quot;variable billow&quot; or &quot;variable geometry&quot;.  A sail which billows more in the middle will naturally give you higher dihedral.  The tradeoff of course is higher drag, which is why it's controllable - pilots pull on VB/VG for best performance in glides, and let it off for tight manoeuvring (e.g thermalling) or slow flying (e.g. takeoff/landing).&lt;/p&gt;&#xA;" OwnerUserId="12155" LastActivityDate="2015-11-06T15:39:00.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22737" PostTypeId="1" AcceptedAnswerId="22740" CreationDate="2015-11-06T15:45:31.760" Score="3" ViewCount="377" Body="&lt;p&gt;It seems that flying a plane in a slip can &lt;a href=&quot;https://aviation.stackexchange.com/a/22686/5517&quot;&gt;make passengers uncomfortable&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is it about that configuration that is unsettling?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-11-06T15:57:40.387" Title="Why is flying in a slip uncomfortable?" Tags="&lt;passenger&gt;&lt;crosswind&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22738" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T15:48:41.387" Score="7" Body="&lt;p&gt;&quot;Wouldn't this make it more economic as there would be savings on material and wiring?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not necessarily, because the days of &quot;one wire per function&quot; are long over.  Automotive has pushed that forward, and aerospace is following.  Modern systems tend to be networked. This actually gives better reliability for less wiring, because it's easier to duplicate individual network cables than to duplicate a 6&quot;-wide bundle of wires carrying the same information.  Superficially the cockpit may still have 30-year-old switches and dials, but expecting 30-year-old wiring under the surface is generally incorrect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;They could also be less susceptible to failures as traditional switches and knobs still rely on mechanical actions.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So do touchscreens to some extent.  As for numbers of failures, how robust is your phone screen to minor impacts, compared to the switches on your car dash?&lt;/p&gt;&#xA;" OwnerUserId="12155" LastActivityDate="2015-11-06T15:48:41.387" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22739" PostTypeId="2" ParentId="22737" CreationDate="2015-11-06T15:54:13.733" Score="-1" Body="&lt;p&gt;Slipping a plane is a form of &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight&quot; rel=&quot;nofollow&quot;&gt;uncoordinated flight&lt;/a&gt; during such a case the plane is inherently unstable and more susceptible to turbulence as caused by unstable air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the advantages of &lt;a href=&quot;http://www.downwindmag.com/2009/11/149/&quot; rel=&quot;nofollow&quot;&gt;coordinated flight&lt;/a&gt; are &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Coordinated flight is usually preferred over uncoordinated flight for the following reasons:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;Comfort level of the passengers (the seat of their pants won’t be going this way and that).&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Drag is kept to a minimum, helping to maximize the margin between actual air speed and stall speed.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Fuel will continue to be drawn equally from tanks in both wings,&#xA;  especially important after a long flight when fuel level may be low&#xA;  (of course you planned your flight to land with legal reserves,&#xA;  right?).&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;No cross controlling, no stalls, therefore no spins (bad, very bad).&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To answer the question directly its the bumps that are unsettling however this is dependent on the situation. In calm air you, as a passenger would never know (but in calm air you really don't need to slip a plane). In a small GA plane where you can better see whats going on it may appear confusing on final approach the pilot is using heavy control inputs and the plane is moving straight (towards the runway that is)  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-06T15:54:13.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22740" PostTypeId="2" ParentId="22737" CreationDate="2015-11-06T15:57:40.387" Score="7" Body="&lt;p&gt;A slip is uncoordinated flight and this shifts the effective gravity vector you experience.  Passengers in the back are also at a disadvantage without a visual horizon in front of them.  This can induce a mismatch between what the passengers can see versus what they are physically experiencing.  In some people this can cause discomfort and potentially vertigo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other discomfort can be psychological in nature that the airplane isn't behaving how they expect.  Passengers expect if a plane isn't turning that the wings are level.  If you are flying when the plane lands in a crosswind with a slight bank and touching down with one main gear, then the other main gear, many passengers will comment that the landing was incorrect because the main gear didn't all touch down together and the pilot was flying &quot;sideways&quot;.  They don't realize the wind requires this technique and that the landing was in fact correct.  The perception of things not being right, however, can cause discomfort in some passengers. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-06T15:57:40.387" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22741" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T16:35:27.987" Score="2" Body="&lt;p&gt;The A380's maiden flight was in 2005.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;iPhone's release was in 2008.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes development cycles are drastically longer than phones, and require very reliable materials.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We just didn't had readily available large capacitive touch screen when engineers started designing the A380's cockpit.&lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="4105" LastEditDate="2015-11-06T17:14:10.483" LastActivityDate="2015-11-06T17:14:10.483" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22742" PostTypeId="2" ParentId="22734" CreationDate="2015-11-06T16:38:07.990" Score="3" Body="&lt;p&gt;The canard flap is like any other control surface in the trailing edge of a canard. The canard flaps are there mainly for trimming the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At transonic speeds, the center of pressure of the aircraft moves rearward, resulting in instability. This could be countered by trimming with the elevons; however, this increases the angle of attack (the elevon deflection in XB70 was between $0^{\circ}$ and $10^{\circ}$)- resulting in increased drag. The small flaps in the XB70's canard was used to counter the movement of center of pressure without changing the main wings AoA, which eliminated the speed and range penalty due to increased drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage is during the landing. The landing attitude of delta aircraft is usually steep and fast compared to other aircraft. The deflection of canard flaps in the XB-70 pitched the nose up, enabling the elevons to be operated as trailing edge flaps- this helped the to keep the landing attitude shallower and speed, lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, in case of XB-70, the canard was exclusively a trimming device- the longitudinal control was provided solely by the elevons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During landing, the use of flaps cause a negative pitching moment- In aircraft with horizontal stabilizers, flap deployment may increase the downward airflow on the horizontal tail, producing a pitch up moment. in case of aircraft without stabilizers, it is not possible. In order to trim the aircraft, the canard flaps in Saab Viggen were deployed; in case of Beechcraft starship, a variable sweep canard was used for the same purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantage of having flaps in canard was the increased complexity. The canard can in itself be used to provide the required trim; the flaps are used only when the canard is highly loaded and may not have sufficient spare lifting capacity to accommodate large movements of the centre of pressure or of the centre of gravity. Note that in case of XB-70, initially, the canard was fixed and the flaps were adjustable; later the canards were made trimmable with the flap deflection set at two positions- $0^{\circ}$ and $20^{\circ}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References: &lt;em&gt;WarbirdTech: North American XB-70A Valkyrie&lt;/em&gt; by Dennis R. Jenkins and Tony Landis; &lt;em&gt;Summary of Preliminary Data Derived from the XB-70 Airplanes&lt;/em&gt; by William H. Andrews, NASA Technical Memorandum TM X-1240&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-06T16:38:07.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22743" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T16:38:11.457" Score="117" Body="&lt;p&gt;Adding a pilot's perspective to what others have said:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at the switches and knobs in an airplane up close some time. You'll notice that nearly all of them have different textures,heights,sizes or shapes. That's intentional. Pilots train and train and train and train on checklists, especially the emergency ones. Muscle memory is a big part of quickly and correctly executing an emergency checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, flap levers/switches normally have a cap or top that is flat and parallel to the wings. It's easy to identify solely by touch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Checklist item: &quot;flaps up&quot;&#xA;Action: Hand to flap lever (automatic after doing it a hundred times in training), verify feel of lever, move, look to verify&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the tactile element, every motion would have to be verified by looking before it's made. With the tactile element, the movement can be made and then verified visually while the hand is moving to the next item. In an emergency, every second counts and the savings from tactile + verify matters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond emergency procedures, they're simply safer. The plane I fly the most has a touch screen display and several non touch devices. In turbulence, the touch screen is basically useless. But, the important devices all have buttons and knobs. I can be banging my head on the ceiling (literally) and still adjust the auto-pilot or radio. In that kind of turbulence, the touch screen device is completely useless.&lt;/p&gt;&#xA;" OwnerUserId="12159" LastActivityDate="2015-11-06T16:38:11.457" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22745" PostTypeId="1" AcceptedAnswerId="22746" CreationDate="2015-11-06T17:00:49.877" Score="12" ViewCount="5135" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;XB-70&lt;/a&gt;'s wing tips folded down in flight to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;improve directional stability at supersonic speeds&lt;/li&gt;&#xA;&lt;li&gt;reduce shifting of aerodynamic center at supersonic speeds&lt;/li&gt;&#xA;&lt;li&gt;reduce drag at high supersonic speeds&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;With thanks to Peter Kämpf's &lt;a href=&quot;https://aviation.stackexchange.com/a/22712/5517&quot;&gt;answer&lt;/a&gt;. Actually, this question was prompted by that answer, and quite a bit of it is 'borrowed' from there.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wings in flight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pxZcm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pxZcm.jpg&quot; alt=&quot;XB70 in flight&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: interceptor.com&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing with wings straight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.kinja-img.com/gawker-media/image/upload/zrzh0oykie7im6555fdg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.kinja-img.com/gawker-media/image/upload/zrzh0oykie7im6555fdg.jpg&quot; alt=&quot;XB70 landing&quot;&gt;&lt;/a&gt;&lt;sup&gt;Source: Gawker Media&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question is why did they &lt;em&gt;fold&lt;/em&gt;, instead of being &lt;em&gt;fixed&lt;/em&gt; in the down position?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My assumption is that the plane already sat very high off the ground (probably to give clearance for take off/landing rotation), and lengthening the landing gear enough to allow the wing droop would have been a greater engineering issue than making the wing folding mechanism. Is there validity in that assumption, or, were the benefits of the wing droop at supersonic speeds detrimental at subsonic speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some perspective of just how tall the XB70 was &lt;sub&gt;(click to zoom - that's a tall bird!)&lt;/sub&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nC9w9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nC9w9.jpg&quot; alt=&quot;XB70 perspective&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: cybermodeler.com&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="14897" LastEditDate="2021-04-05T12:09:46.670" LastActivityDate="2021-04-05T12:09:46.670" Title="Why weren't the XB-70's wingtips fixed in the down position?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;folding-wings&gt;&lt;xb-70-valkyrie&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="22746" PostTypeId="2" ParentId="22745" CreationDate="2015-11-06T17:07:53.587" Score="19" Body="&lt;p&gt;Well, for starters, the drooped wing is not producing any lift in subsonic speeds. So, the flat area (the fixed part) should be significantly larger for producing the lift. This increases weight, which leads to a vicious cycle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is the wing would panels would not clear the ground while the aircraft was on its landing gear. For testing the wing fold in ground, the aircraft had to be put on tall jackstands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oumdP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oumdP.jpg&quot; alt=&quot;XB-70A wing testing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from keypublishing.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you noted, lengthening the landing gear enough to allow the wing droop would have been a big issue not the least because the aircraft weight was already increasing alarmingly (the weight had shot up from 483,000 lb to 537,000 lb).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, you lose the outboard elevons; now for getting the same control response the inboard control surfaces have to be increased in size, which has to be come either from wing or increase the wing area- it is again a mess.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-06T17:25:33.653" LastActivityDate="2015-11-06T17:25:33.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22747" PostTypeId="1" AcceptedAnswerId="22754" CreationDate="2015-11-06T17:28:33.650" Score="1" ViewCount="9321" Body="&lt;p&gt;These are related to MROs(Maintenance, repair and operations) activities ?&lt;/p&gt;&#xA;" OwnerUserId="12014" LastActivityDate="2015-11-06T23:33:22.497" Title="What are the differences between third-party base maintenance, line maintenance and component maintainance?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22749" PostTypeId="2" ParentId="22729" CreationDate="2015-11-06T19:32:00.300" Score="5" Body="&lt;p&gt;Ive had touch devices misread my intentions many factors of factors times more often than mechanical switches. Furthermore you can operate mechanically arranged interfaces without looking, ie. &lt;em&gt;by feel&lt;/em&gt;. In fact, having an interface that responds when you touch it is not at all what you want to happen when safety is a major concern.&lt;/p&gt;&#xA;" OwnerUserId="1662" LastActivityDate="2015-11-06T19:32:00.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22750" PostTypeId="1" CreationDate="2015-11-06T19:52:58.027" Score="3" ViewCount="269" Body="&lt;p&gt;I found a 4-5' styrofoam wing in eastern Montana in a field. It has what looks like a registration number on it. How can I trace that number to try to return it?&lt;/p&gt;&#xA;" OwnerUserId="12163" LastEditorUserId="19" LastEditDate="2016-11-01T11:43:50.960" LastActivityDate="2016-11-01T11:43:50.960" Title="How to locate the owner of a 5' styrofoam wing found in a field?" Tags="&lt;aircraft-registration&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22751" PostTypeId="2" ParentId="22750" CreationDate="2015-11-06T20:28:34.830" Score="13" Body="&lt;p&gt;If it has a US registration number on it (N followed by 1-5 numbers or letters) &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/nnum_inquiry.aspx&quot;&gt;you can search the FAA registration database&lt;/a&gt; to find out what aircraft has that particular registration number, and who owns it.&lt;br&gt;&#xA;In the case of a 4-5 foot styrofoam wing this would likely only be useful if the aircraft in question was a registered UAV.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some common sense needs to prevail here: Model aircraft often have an N number painted on them for decorative reasons, so if you look up N12345 and it says &quot;That belongs to a Piper Cub&quot; you can safely assume this wing &lt;em&gt;does not&lt;/em&gt; belong to that particular real-world aircraft (as the Cub's wings are not made from styrofoam, and are more than 5 feet long).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2015-11-06T20:28:34.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22752" PostTypeId="2" ParentId="22747" CreationDate="2015-11-06T20:58:59.383" Score="5" Body="&lt;p&gt;&lt;strong&gt;Base maintenance&lt;/strong&gt;: The maintenance work is done in a hangar, with special tools and equipment. Third-party just means that someone else than the operator of the aircraft is running the shop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Line maintenance&lt;/strong&gt;: The work is done on the flight line, basically on the apron out in the open.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Component maintenance&lt;/strong&gt;: The work is done on some component that had been removed from the aircraft before. Typically, this item had been swapped against a good one in line maintenance and is now looked at in detail in a specialist shop. Items like this are called &lt;a href=&quot;https://en.wikipedia.org/wiki/Line-replaceable_unit&quot;&gt;LRU&lt;/a&gt; (line-replaceable unit). Components could also be as large as a whole engine which needs to be serviced in a special shop and is removed during base maintenance.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-06T21:04:38.370" LastActivityDate="2015-11-06T21:04:38.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22753" PostTypeId="1" CreationDate="2015-11-06T22:10:22.697" Score="0" ViewCount="67" Body="&lt;p&gt;Are there any systems in a manned aircraft which can be controlled by the ATC/ground control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be specific, could you name some tested and existing procedures/systems which make it possible to change aircraft dynamics such that it is manipulated from outside the cockpit of the aircraft and the pilot is overridden?&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="3142" LastEditDate="2015-11-06T22:32:20.220" LastActivityDate="2015-11-06T22:32:20.220" Title="Extent of ATC control on an aircraft" Tags="&lt;air-traffic-control&gt;&lt;flight-controls&gt;&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="8" FavoriteCount="0" ClosedDate="2015-11-06T22:30:57.127" ContentLicense="CC BY-SA 3.0" />
  <row Id="22754" PostTypeId="2" ParentId="22747" CreationDate="2015-11-06T23:33:22.497" Score="2" Body="&lt;p&gt;These are indeed related to MRO activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Line maintenance&lt;/strong&gt; generally refers to minor, unscheduled or scheduled maintenance carried out on aircraft that occurs at or near the gate or terminal (Tarmac), launch area, ready area, hardstand or alert area. This is usually carried out by the operator. This is the basic level of maintenance and is limited by the ground support equipment available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third Party Base Maintenance&lt;/strong&gt; refers to the base maintenance (i.e. maintenance done in aircraft hangar with special tools) carried out by a third party- other than the manufacturer and the operator. This is usually the next level of maintenance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Component maintenance&lt;/strong&gt; refers to the maintenance carried out on some component removed from the aircraft (for e.g. rotable or LRU) due to fault or completion of specified service time in a dedicated shop or lab. These are usually done for avionics units, engines, transmission items etc. This is usually done by the OEM or their authorized agent.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-06T23:33:22.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22755" PostTypeId="2" ParentId="2920" CreationDate="2015-11-07T02:42:52.167" Score="0" Body="&lt;p&gt;bottom cylinders can get oil that leaks above the piston after setting idle. If this is not managed, damage will result.  They walked the prop through by hand in old wwII planes to clear this oil.&lt;/p&gt;&#xA;" OwnerUserId="12168" LastActivityDate="2015-11-07T02:42:52.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22756" PostTypeId="1" AcceptedAnswerId="22839" CreationDate="2015-11-07T03:46:29.203" Score="4" ViewCount="656" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;This is a follow-up to my previous question here -&#xA;  &lt;a href=&quot;https://aviation.stackexchange.com/questions/22139/lost-radio-communication-after-take-off-in-imc-what-are-my-options&quot;&gt;Lost radio communication after take-off in IMC - what are my options?&lt;/a&gt;.&#xA;  Please refer to that to understand the scenario of this question.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If, for e.g, at one point during the flight, I see a minimum en-route of 9000' and so I climb up to 9000' from 8000'. Now, if the next segment has a minimum en-route altitude of 3000', shall I go back to my previously held altitude of 8000' (&lt;em&gt;which became my assigned altitude before and is now the maximum amongst all the other available altitudes&lt;/em&gt;) or shall I maintain 9000' and &lt;strong&gt;consider it to be my &quot;new&quot; assigned altitude&lt;/strong&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from a regulatory perspective, I'd also like if someone could weigh-in on practical perspective - would it be better in terms of traffic separation for ATC, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question really is - is it practical to descend, or do the regulations want you to descend and hence ATC does not expect you to descend?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've had different answers to this particular question from different Flight Instructors, and hence looking for a definite answer.&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-11-11T03:10:37.297" Title="Is it practical to descend in a lost communication scenario?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;ifr-navigation&gt;&lt;lost-communications&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22757" PostTypeId="1" CreationDate="2015-11-07T14:42:37.613" Score="15" ViewCount="14133" Body="&lt;p&gt;I know there are advantages of swept-back wings delaying shock-wave allowing a aircraft to fly faster. However, what are the disadvantages.&#xA;I know one of them is that they have very poor low speed characteristics, however I do not know the reason. Another disadvantage will be on the F-100 Super Sabre Dance, do not understand these either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can any kind soul explain the disadvantages?&lt;/p&gt;&#xA;" OwnerUserId="12175" LastEditorUserId="1961" LastEditDate="2015-11-07T23:35:45.210" LastActivityDate="2020-03-10T17:23:06.437" Title="What is the reason for the poor low-speed characteristics of sweptback wings?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aerospace-materials&gt;&lt;aeroelasticity&gt;&lt;wing-sweep&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22758" PostTypeId="2" ParentId="22757" CreationDate="2015-11-07T15:15:40.947" Score="22" Body="&lt;h2&gt;Disadvantages of wing sweep&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lift curve slope is reduced by the cosine of the quarter chord sweep angle. This means more angle of attack for takeoff, which requires a longer take-off run and a longer landing gear to avoid a &lt;a href=&quot;https://aviation.stackexchange.com/questions/14647/how-do-manufacturers-engineer-their-aircraft-to-deal-with-tail-strikes&quot;&gt;tail strike on rotation&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;If you rotate the airplane, the tips of backward swept wings come down when the aircraft rotates for take-off. This also might drive the requirement for a longer landing gear.&lt;/li&gt;&#xA;&lt;li&gt;Bending moments in the wing will become torsion moments when you change the sweep angle. And you will need to change it at least in the wing root where the wing connects to the fuselage. This translates into a heavier structure.&lt;/li&gt;&#xA;&lt;li&gt;If your sweep angle and aspect ratio both are large enough, the wing will show nasty stall characteristics. The boundary layer is swept towards the tips and causes earlier separation when the wing stalls, and the airplane will pitch up or roll uncontrollably. Wing fences help, but cannot completely remedy this.&lt;/li&gt;&#xA;&lt;li&gt;Wing sweep &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292#9292&quot;&gt;causes a yaw-induced rolling moment&lt;/a&gt;, so less dihedral is needed. On high wing airplanes &lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/why-does-an-225-have-anhedral-wings-though-it-is-a-cargo-aircraft&quot;&gt;this requires to use anhedral&lt;/a&gt;. Unfortunately, this rolling moment varies with lift coefficient, so your yaw-induced rolling moment on a swept aircraft is lower than ideal at high speed and higher at low speed.&lt;/li&gt;&#xA;&lt;li&gt;For flying wings, sweep will let the aircraft center pitch up and down when the wing flexes. This creates a powerful interaction between the fast period mode (which is only moderately damped in flying wings) with the wing bending mode, resulting in flutter.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, when having a choice, the clever airplane designer &lt;a href=&quot;https://aviation.stackexchange.com/questions/15349/optimal-wing-sweep-angle-for-passenger-airliner/15362#15362&quot;&gt;avoids sweep whenever he/she can&lt;/a&gt;. But sweeping a wing back is still &lt;a href=&quot;https://aviation.stackexchange.com/questions/2360/what-are-the-advantages-of-a-forward-swept-wing-over-a-rearward-swept-wing/12855#12855&quot;&gt;better than forward sweep&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Low Speed Characteristics&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;An airfoil &lt;a href=&quot;https://aviation.stackexchange.com/questions/21664/how-complete-is-our-understanding-of-lift/21685#21685&quot;&gt;initially accelerates the air which flows over its top surface and decelerates it again over its rear part&lt;/a&gt;. On swept wings, this acceleration-deceleration only affects the orthogonal speed component, so the speed component in span direction remains unaffected. This is the reason for the higher Mach capability of swept wings, but also causes the air to flow first inwards and then outwards while transversing the wing's upper surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top, friction decelerates the air flowing around a body, such that a layer of decelerated air surrounds each surface of an airplane. The thickness of this &lt;a href=&quot;https://en.wikipedia.org/wiki/Boundary_layer&quot; rel=&quot;noreferrer&quot;&gt;boundary layer&lt;/a&gt; increases with flow length, and on a swept wing this friction will initially mostly affect the orthogonal flow component. At around mid chord you will find air which has been decelerated mostly in its orthogonal speed component (since this component was so high over the forward part) and now will be subject to more deceleration of the orthogonal component, so that only the spanwise component will be left over the rear part of the boundary layer. Now this boundary layer will only flow off in span direction, such that a massive increase of slow, low-energy air will be collecting towards the tips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A thick boundary layer will &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=7%7C0.1517#5055&quot;&gt;cause early flow separation&lt;/a&gt;, so when the angle of attack is increased, the flow at the tips of a backward swept wing will separate first. This will cause lift loss, and since the tips are also the rearward part of the wing, will shift the aerodynamic center forward. This in turn will make the aircraft pitch up, which aggravates the stall condition. If the separation happens asymmetrically, the aircraft will roll in addition to pitching up. In case of the F-100, the tail surfaces were too small to stop the pitch-up, so once the aircraft crossed into the stall region, it would uncontrollably pitch up more and stall completely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern swept-back aircraft have an angle-of-attack limiter which will prevent the aircraft from flying into the stall region. Also, wing fences help to keep the spanwise flow in check, and vortex generators help to energize the flow such that the early flow separation at the wing tips is sufficiently delayed to avoid the uncontrollable pitch-up. The F-100 lacked all those remedies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fABY1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fABY1.jpg&quot; alt=&quot;Wing fences on a MiG-17&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing fences on a MiG-17 (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/MiG-17F_Top_View.JPG/800px-MiG-17F_Top_View.JPG&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4nRPW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4nRPW.jpg&quot; alt=&quot;Vortex generators on a Boeing 737 wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortex generators on a Boeing 737 wing (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/3/3c/Interior_of_westjet_winglet_crop.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-11-28T03:36:28.280" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22759" PostTypeId="1" AcceptedAnswerId="22760" CreationDate="2015-11-07T15:31:43.697" Score="8" ViewCount="611" Body="&lt;p&gt;Not all aircraft can be docked from the right seat, because they have a wheel tiller only on the captain's side, but some can (e.g. the &lt;a href=&quot;http://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2008/a08q0171/images/a08q0171_photo_2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;B747-400&lt;/a&gt; of the linked question).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The usual docking system at gates looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nT9bx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nT9bx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.fsdeveloper.com/forum/threads/docking-systems.562/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems the azimuth guidance is based on parallax, and is designed for the left seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;What happens if the pilot in charge of docking the aircraft is seated on the right side? How is the alignment performed without the support of the visual docking system?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/1904/are-large-passenger-aircraft-steered-during-taxi-by-changing-the-angle-of-the-fr&quot;&gt;Are large passenger aircraft steered during taxi by changing the angle of the front landing gear?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-11-02T16:57:03.227" Title="Can an aircraft be docked at the gate from the right seat?" Tags="&lt;cockpit&gt;&lt;airport-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22760" PostTypeId="2" ParentId="22759" CreationDate="2015-11-07T16:02:28.970" Score="9" Body="&lt;p&gt;&lt;s&gt;The system you showed may actually be the type that &lt;strong&gt;does not&lt;/strong&gt; depend on the position on the pilot.&lt;/s&gt; Edit: The version you have works with a Moiré pattern, and is indeed dependent on which pilot is looking at it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I dug into the AIS Netherlands information for our country's biggest airport Schiphol (EHAM/AMS). They have a &lt;a href=&quot;https://web.archive.org/web/20151106134953/http://www.ais-netherlands.nl/aim/2015-09-03-AIRAC/eAIP/html/eAIP/EH-AD-2.EHAM-en-GB.html#ssid-1109062702433&quot; rel=&quot;nofollow noreferrer&quot;&gt;few different systems&lt;/a&gt;; the one you link seems to be a lot like the SAFE DOCK system, which uses a Laser Range Finder (LRF) system to identify the position of the aircraft&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Due to the digital display presentation, both pilots get the correct alignment information as well as the closing-rate and stop information.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that this system will become more common to allow for more flexible crew tasks during taxi. Furthermore, this system can detect obstacles, and as such provides extra safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two other systems on EHAM do depend on the seating of the pilot. The effect of the wrong pilot parking the plane is very simple: your plane will be parked off-center with a deviation exactly equal to the spacing between the pilots: your plane will end up such that the co-pilot is sitting where the captain should be. The fact that the AIS does not quote any procedures for this says it all: you just shouldn't do it and wake the captain for a minute to do his duties.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there are procedures for when the system is not available (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The system is operated by an employee of a handling company, who also &lt;strong&gt;keeps a safety watch during the docking&lt;/strong&gt;. The pilot of an arriving aircraft has to be sure that the system is activated. If not, pilots should not enter the aircraft stand and stop before the red boundary line, until the system is activated &lt;strong&gt;or a marshaller has signalled clearance to proceed&lt;/strong&gt;. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The logical conclusion we can draw here is that, if the systems are not available (or, in the case of the question, if the captain is fast asleep), a marshaller will guide the plane in - either way, a marshaller will stand by to oversee the docking and make sure the SAFE DOCK system is living up to its name.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @reirab helpfully pointed out, the marshaller's job may be nothing more than a simple clearance to enter the gate and let the pilots do their job; they should be perfectly capable of parking an aircraft without the displays. In the aviation world, it's perfectly acceptable to spend a lot of money on these things if they can increase safety; if only due to reduced workload for the pilots.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2016-11-02T16:57:03.227" LastActivityDate="2016-11-02T16:57:03.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22761" PostTypeId="2" ParentId="22757" CreationDate="2015-11-07T16:02:41.717" Score="15" Body="&lt;p&gt;Wing sweep improves the performance by delaying the shock waves and accompanying aerodynamic drag rise caused by fluid compressibility at high (near sonic) speeds. However, there are some disadvantages associated with the wing sweep like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing sweep reduces the slope of the lift curve and the maximum lift coefficient of the wing. This means that the swept wing aircraft must fly at a higher AOA to achieve maximum lift. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HmehF.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HmehF.png&quot; alt=&quot;Wing sweep effect on lift curves&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: code7700.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing sweep induces spanwise flow along the wing, which means that the air has to travel longer distance over the wing. This means a thicker boundary layer and more chances of flow separation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TUlX6.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TUlX6.jpg&quot; alt=&quot;Spanwise flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: boldmethod.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The spanwise flow on swept wings increases the effective angle of attack of wing segments relative to its neighboring forward segment; the result being the rear segments of the wing stall first (tip stall for rearward swept wings and root stall for forward swept wings). If the resulting nose-up pressure (due to the fact that the lift vector moves forward) is not corrected, the aircraft pitches up further, extending the stalled region, resulting in a vicious cycle, resulting in complete stall of aircraft. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is the reason for the 'Sabre dance' experienced in F-100 Super Sabre. This is further exacerbated by the already high angles of attack during takeoff and landing, as already noted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8d0Dd.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8d0Dd.png&quot; alt=&quot;Stall progression&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: code7700.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Wing bending moments cause torsion in case of swept wings. This requires strengthening of wings, or a complicated design. This affects the forward swept wings to a larger degree than the rearward swept wings , and is one of the main reasons the forward swept wings are not used much.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One important consideration due to wing sweep is the high speed aileron reversal. In case of streamwise angles of twist resulting from wing bending and aileron pitching moment add together, resulting a large amount of nose down wing twist, which reduces aileron effectiveness. Due to this swept back wings have low aileron reversal speeds (while swept forward wings have higher values). This problem is not experienced in wings with constant sweep.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-07T16:02:41.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22762" PostTypeId="1" AcceptedAnswerId="22763" CreationDate="2015-11-07T17:24:17.300" Score="1" ViewCount="2656" Body="&lt;p&gt;I'd like to know the interval of altitudes airliners usually cruise at (and its reasons)? And if there are international restrictions about this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also I read somewhere that recently about a restriction that airliners should not fly bellow 26000 ft over egypt. How hard that restriction would be?&lt;/p&gt;&#xA;" OwnerUserId="8415" LastActivityDate="2015-11-07T17:51:46.587" Title="What is the typical cruising altitude for a civil airplane?" Tags="&lt;airliner&gt;&lt;regulations&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2015-11-08T02:17:49.223" ContentLicense="CC BY-SA 3.0" />
  <row Id="22763" PostTypeId="2" ParentId="22762" CreationDate="2015-11-07T17:35:35.527" Score="2" Body="&lt;p&gt;I think there are already plenty of answers here to give you a clue:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3272/how-do-pilots-decide-what-their-cruising-altitude-will-be&quot;&gt;How do pilots decide what their cruising altitude will be?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/20694/why-are-regional-cruising-altitudes-higher-than-those-of-international-much-long&quot;&gt;why are regional cruising altitudes higher than those of international much longer flights?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/4967/how-can-you-find-the-best-altitude-for-range-or-speed&quot;&gt;How can you find the best altitude for range or speed?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12541/why-are-many-jet-aircraft-designed-to-cruise-around-fl350-370&quot;&gt;Why are many jet aircraft designed to cruise around FL350-370?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Normally, atitude restrictions give a top limit. A minimum altitude is hard to enforce when one engine fails - then the aircraft can only continue at a lower altitude (typically around 15,000 ft for a two-engined jet) or the cabin pressurization fails (now the aircraft needs to continue below 10,000 ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is speculation, but maybe the 26,000 ft limit is caused by information that rebels in the West Sinai have gotten hold of &lt;a href=&quot;http://fas.org/asmp/campaigns/MANPADS/MANPADS.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;shoulder-launched anti-aircraft missiles&lt;/a&gt;. Those have a fairly low upper limit to their effectiveness.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-11-07T17:51:46.587" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22764" PostTypeId="2" ParentId="22762" CreationDate="2015-11-07T17:51:33.010" Score="1" Body="&lt;p&gt;It depends on the type of airliner.  They all fly high to take advantage of a higher &quot;true airspeed&quot; (TAS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Smaller turboprops like the Beech 1900, SA226, and SA227 might cruise in the low to mid 20,000 foot band.  Jets will usually cruise above 30,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air is thinner at high altitudes which reduces drag on the airplane and allows it to slip through the air at a higher &quot;true&quot; airspeed.  Turbine engines are optimized to run at high altitudes and by running in to 20,000 - 30,000 foot altitude band, they can still generate enough power to propel the aircraft along at a couple hundred knots using far less fuel than they would at sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airspeed indicator in a jet cockpit will indicate something like 250 knots, the true airspeed will actually be 400 knots, and the ground speed will equal true airspeed plus or minus the wind component.  Why the big difference between indicated airspeed and true airspeed?  The thin air &quot;tricks&quot; the airspeed indicator!  There are simply fewer air molecules at 20,000 than at seal level and since the airspeed indicator in the cockpit needs air molecules to determine the speed, the thinner air fools the indicator into thinking the plane is going slower than it really is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The true airspeed corrects for this by taking into account the thinner air and temperature to tell the pilot &quot;hey, your airspeed indicator tells you that you're speed is 250 knots.  But since you're up high and the air is thinner, I've done the calculation to determine your REAL speed through the air...it's 400 knots!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At sea level, a jet will indicate 250 knots.  The atmosphere is thick at sea level so the indicated and true airspeed will be fairly close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same jet at 30,000 feet will indicate 250 knots but the true airspeed will be much higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taken to an extreme, a spacecraft in orbit has a speed of many thousands of miles per hour.  What's the airspeed?  ZERO!  There is no more atmosphere so the airspeed indicator (which relies on air molecules, remember) can't register an airspeed.  The ground speed of the spacecraft is extremely high, though.  Now, toss in a thin atmosphere and your indicator will begin to show you a speed.  It will be low because the air is thin but your actual (TRUE) airspeed will be very high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the Egyptian altitude restrictions go, I haven't a clue.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2015-11-07T17:51:33.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22765" PostTypeId="1" AcceptedAnswerId="22767" CreationDate="2015-11-07T19:32:42.203" Score="11" ViewCount="3625" Body="&lt;p&gt;I've been reading more about the development of the A-12, which in turn referenced the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan&quot;&gt;CL-400 Suntan&lt;/a&gt;. I noticed that the engines are located at the end of the wing, rather than integrated with the fuselage or on the midpoint, which is not something I've seen (or at least noticed) on any other aircraft (the closest thing I'm aware of is tip jets on helicopters). What is the design rationale behind locating engines on the end of the wing, and indeed for other locations?&lt;/p&gt;&#xA;" OwnerUserId="11559" LastEditorUserId="167" LastEditDate="2015-11-08T06:59:43.690" LastActivityDate="2016-08-11T21:10:13.177" Title="Why did the CL-400 Suntan have engines on the ends of its wings?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22766" PostTypeId="2" ParentId="22549" CreationDate="2015-11-07T20:08:19.307" Score="-1" Body="&lt;p&gt;User11933, has reproduce the legislation refering to those specific items.To answer your other question ie:who checks it.The flight attends do, in theory. After each flight they are supposed to check and make sure none is missing.It is part of the equipment of the aircraft and as such, listed in the MEL.(Minimum equipment list) which is the document listing all the systems and equipment mandadory on board.&#xA;Obviously the captain is ultimately responsible. On smaller aircrafts with no FA, it is actually up to him or to the FO by delegation, to make sure they are on board before departure.&#xA;Hope that clears it up :-)&lt;/p&gt;&#xA;" OwnerUserId="3980" LastActivityDate="2015-11-07T20:08:19.307" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22767" PostTypeId="2" ParentId="22765" CreationDate="2015-11-07T22:33:14.030" Score="22" Body="&lt;p&gt;The Suntan project needed all fuselage space to hold three tanks for liquid hydrogen, so the engines had to be placed somewhere else. Placing them near the fuselage would put them in the range of the fuselage's shock waves. Putting them out on the wing would help with wing bending relief and ensure a clean intake flow. Once they are so far out, you can as well put them on the wingtips, so that they do not cause a pitch-up moment. On the SR-71, the engines were also placed outside the fuselage and into the wing's plane, much for the same reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keeping the intake flow uniform is paramount for the undisturbed operation of supersonic intakes, and I assume that Kelly Johnson wanted to make sure that the engines would not suffer an unstart when flying reconnaissance missions over hostile territory. With the little experience in supersonic flight in 1955 it was prudent to avoid built-in pitching moments - after all, the supersonic L/D likely was in the single digits, so an out-of-plane engine placement would had produced more moment than on subsonic aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydrogen was selected to achieve the highest possible flight altitude, so the aircraft would be safe from surface-to-air missiles for as long as possible. I initially thought that the wingtip location would enable to cool the hot wing structure by heating up the hydrogen on its way to the engine, but heating was planned to be done with bleed air in a special heat exchanger. Quoting &lt;a href=&quot;http://www.history.nasa.gov/SP-4404/ch8-5.htm&quot; rel=&quot;noreferrer&quot;&gt;www.history.NASA.gov&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The CL-400 design divided the hydrogen tankage into three sections;&#xA;  the forward tank had a capacity of 67 000 liters; aft, 54 000; and&#xA;  center (sump), 15 000. The two main tanks were kept at 2.3 atmospheres&#xA;  pressure and the sump tank slightly lower for fuel transfer. In the&#xA;  sump was a booster pump, built by Pesco Products, that supplied liquid&#xA;  hydrogen to the engines at a pressure of 4.4 atmospheres. The engines&#xA;  were mounted at the wing tips, which meant that the liquid hydrogen&#xA;  had to pass through a hot wing with surface temperatures up to 436 K.&#xA;  The design provided a vacuum-jacketed, insulated line for this&#xA;  purpose.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Regarding the perceived danger of using hydrogen, &lt;a href=&quot;http://www.history.nasa.gov/SP-4404/ch8-6.htm&quot; rel=&quot;noreferrer&quot;&gt;www.history.NASA.gov&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tests were devised in which tanks containing liquid hydrogen under&#xA;  pressure were ruptured. In many cases, the hydrogen quickly escaped&#xA;  without ignition. The experimenters then provided a rocket squib (a&#xA;  small powder charge) to ignite the escaping, hydrogen. The resulting&#xA;  fireball quickly dissipated because of the rapid flame speed of&#xA;  hydrogen and its low density. Containers of hydrogen and gasoline were&#xA;  placed side by side and ruptured. When the hydrogen can was ruptured&#xA;  and ignited, the flame quickly dissipated -, but when the same thing&#xA;  was done with gasoline, the gasoline and flame stayed near the&#xA;  container and did much more damage. The gasoline fire was an order of&#xA;  magnitude more severe than the hydrogen fire. The experimenters tried&#xA;  to induce hydrogen to explode, with limited success. In 61 attempts,&#xA;  only two explosions occurred and in both, they had to mix oxygen with&#xA;  the hydrogen. Their largest explosion was produced by mixing a half&#xA;  liter of liquid oxygen with a similar volume of liquid hydrogen.&#xA;  Johnson and Rich were convinced that, with proper care, liquid&#xA;  hydrogen could be handled quite safely and was a practical fuel-a&#xA;  conclusion that was amply verified by the space program in the 1960s.&#xA;  At the time, however, Johnson and Rich filmed their fire and explosion&#xA;  experiments to convince doubters.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When work on Suntan started, liquid hydrogen was a laboratory curiosity. Preparing the infrastructure needed for operating the CL-400, the Suntan project led to the building of large-scale liquid hydrogen plants. Their availability paved the way for the cryogenic rockets of the Apollo program!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, a similar engine location was selected by the Russian design bureaus &lt;a href=&quot;http://www.century-of-flight.net/Aviation%20history/evolution%20of%20technology/sov_composites.htm#r&quot; rel=&quot;noreferrer&quot;&gt;Tsybin for their NM-1&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Myasishchev_M-50&quot; rel=&quot;noreferrer&quot;&gt;Myasishchyev for their M-50&lt;/a&gt; supersonic bomber in the mid-50s. It was started after news of the US Weapon System 110 (which later led to the XB-70) reached Russia and was similarly cancelled after two prototypes had been built and only one aircraft had flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4WA8N.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4WA8N.jpg&quot; alt=&quot;M-50 during display in 1961 at Tushino airshow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;M-50 during display in 1961 at Tushino airshow (picture &lt;a href=&quot;http://www.testpilots.ru/tp/russia/myasishchev/m/50/images/m50-2.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the similarity of the Mig-21 and M-50 planform - both originated from the same work done at &lt;a href=&quot;https://en.wikipedia.org/wiki/TsAGI&quot; rel=&quot;noreferrer&quot;&gt;TsAGI&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placing the outer engines below the wing would had caused ground contact on rotation. Speaking of rotation: The M-50 had two central gears and the bomb bay between them, and the main gear had to be placed so far aft that the M-50 could not be rotated the usual way with the elevator. So the engineers devised what they called the &quot;galloping bicycle&quot;. When the aircraft reached 300 km/h, the forward gear rapidly extended to rotate it to 10°. Placing the outer engines B-58-like below the wing would had required an even longer gear.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-08-11T21:10:13.177" LastActivityDate="2016-08-11T21:10:13.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22768" PostTypeId="2" ParentId="22765" CreationDate="2015-11-08T00:21:35.137" Score="5" Body="&lt;p&gt;The position of the engines on wing is determined by a number of factors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aerodynamics: The flow at engine intake should be as undisturbed as possible. The drag should be kept as low as possible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Safety: Any uncontained engine failure should not affect other components (like fuselage, wing or other engines). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Control: In case of multi engined aircraft, asymmetric thrust due to the failure of one engine should not produce uncontrollable yawing moment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Comfort: In case of civil aircraft, the cabin noise due to engine should be minimal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Structural: The location of engines far from the center-line gives beneficial wing bending relief in flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel capacity: the location of engines in pods outside the wing frees up space for fuel in the wing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Maintainability: The engines should be easily accessible for maintenance and repair crew.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The CL-400 had its engines in the wingtips, that freed up the fuselage to carry the fuel. A similar arrangement was found in the &lt;a href=&quot;http://www.testpilot.ru/russia/myasishchev/m/50/m50_e.htm&quot; rel=&quot;noreferrer&quot;&gt;Myasishchev M-50&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ED4W7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ED4W7.jpg&quot; alt=&quot;M-50&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from testpilot.ru&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both were designed to be high speed, long range aircraft, with neither fulfilling their requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another aircraft with wingtip engines was the French &lt;a href=&quot;https://en.wikipedia.org/wiki/SNCASO_Trident&quot; rel=&quot;noreferrer&quot;&gt;Trident&lt;/a&gt;, which was expected to be a rocket powered interceptor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5UYZe.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5UYZe.jpg&quot; alt=&quot;Trident&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:SO.9000_Trident.JPG#/media/File:SO.9000_Trident.JPG&quot; rel=&quot;noreferrer&quot;&gt;SO.9000 Trident&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Deep_silence&quot; rel=&quot;noreferrer&quot; title=&quot;User:Deep silence&quot;&gt;Deep silence&lt;/a&gt; (Mikaël Restoux) - Own work (Bourget museum, in France). Licensed under CC BY-SA 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, some P-51s were fitted with wingtip rocket ramjets for increasing their speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uLKlr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uLKlr.jpg&quot; alt=&quot;P-51&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from jimbrooks.org&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-08T00:21:35.137" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22769" PostTypeId="2" ParentId="3513" CreationDate="2015-11-08T00:56:30.763" Score="2" Body="&lt;p&gt;It is much more expensive to build a turbine engine than a piston engine. Turbine engines can be built that have a longer TBO than a piston engine, partially offsetting that cost, but that matters more to users who have high aircraft utilization per year. One tends to see turbine engines used in commercial operations, 1000s of hours per year, and pistons in private operation 100s of hours per year. As engines get larger and more powerful, piston engines get more expensive and complex because they are limited by engine knock. So turbines dominate at larger sizes for all users. It is all driven by dollars. No bucks, no Buck Rodgers.&lt;/p&gt;&#xA;" OwnerUserId="12180" LastActivityDate="2015-11-08T00:56:30.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22770" PostTypeId="1" CreationDate="2015-11-08T15:55:43.990" Score="8" ViewCount="12748" Body="&lt;p&gt;Suppose a person suffers from motion sickness when flying, but wishes to become a pilot (let us say, with the eventual goal of flying for a major commercial airline).  Is this possible?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Is motion sickness a medical disqualification for a pilot's license, in many or most jurisdictions?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Most over-the-counter motion sickness medications cause drowsiness, so they are obviously not a good idea for a pilot to take.  Do pilots have access to other effective treatments that are safe to use while operating an aircraft?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Do pilots find that they get over motion sickness the more they fly, similar to the way sailors develop &quot;sea legs&quot;?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are pilots taught techniques to remain focused on flying even if they are experiencing motion sickness symptoms (nausea, vomiting, dizziness, etc)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2546" LastActivityDate="2015-11-09T14:41:37.687" Title="Can people who suffer from motion sickness become pilots?" Tags="&lt;medical&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22771" PostTypeId="2" ParentId="14567" CreationDate="2015-11-08T16:19:28.893" Score="2" Body="&lt;p&gt;I am directly quoting from the book 'A Dictionary of Travel and Tourism Terminology' by Allan Beaver.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;sector, segment or leg: A sector is, by definition, a portion of an itinerary, or journey, which may consist of one or more legs or segments. A leg is the portion of a journey between two consecutive scheduled stops on any particular flight. A segment is that portion of a journey, from a boarding point of a passenger, to a deplaning point of the given flight. Although the passenger may not leave the plane, it may tough down to take on or let off passengers at several points, so that a segment may be made up of a leg or group of legs.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12185" LastActivityDate="2015-11-08T16:19:28.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22772" PostTypeId="1" AcceptedAnswerId="22779" CreationDate="2015-11-08T16:54:19.593" Score="11" ViewCount="2758" Body="&lt;p&gt;With many airlines, when a passenger buys a ticket online, there is a space for them to select a &quot;title&quot;, such as Ms., Mr., Dr., Rev., etc.    In most social circumstances, the title &quot;Dr.&quot; is applicable to anyone with a doctoral degree (M.D., Ph.D., D.D., etc).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard a rumor that in the event of a medical emergency on the plane, the cabin crew will check the passenger manifest for people who have given the title Dr., in hopes of finding a medical doctor who can assist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a consequence, goes the rumor, a passenger who has a doctoral degree, but is not a medical doctor (say, a PhD in mathematics), should not choose the title &quot;Dr.&quot; when buying a ticket, since if there is a medical emergency, the cabin crew might waste time asking this mathematician for assistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also heard it said that this is nonsense, that crews would not bother looking at the manifest, and would simply make a PA announcement asking for anyone with medical training.  (This has the advantage that it would also identify medical professionals such as nurses, paramedics, etc., who would not use the title &quot;Dr.&quot; anyway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which of these reflects actual crew training or standard procedures?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best practice for a passenger who holds a non-medical doctorate?  I've never seen any official guidance from an airline on when to use the title &quot;Dr&quot; on a ticket.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I wasn't sure if this question would be best here, or on Travel.SE, or maybe even Skeptics.SE, but I thought this site would be most likely to have people with first-hand knowledge from the crew side.  I'm open to suggestions for migration.)&lt;/p&gt;&#xA;" OwnerUserId="2546" LastEditorUserId="2546" LastEditDate="2015-11-08T17:14:32.867" LastActivityDate="2015-11-09T00:11:51.100" Title="Do crews look for &quot;Dr.&quot; on a passenger manifest to identify medical doctors?" Tags="&lt;emergency&gt;&lt;passenger&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22773" PostTypeId="1" AcceptedAnswerId="22774" CreationDate="2015-11-08T17:54:15.693" Score="29" ViewCount="18046" Body="&lt;p&gt;Why don't modern planes and ATC centers have good-quality audio for communication? For example in this video: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/ixQvvHHH5YQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;br&gt;&#xA;Or basically any other example of pilot communication(some are worse, some are better).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not terribly bad of course, but this is comparable to a cheap $4 headset, the sound is so distorted. This can cause trouble when a pilot does not understand some words and asks to repeat the sentence. And even more problems if the pilot or flight dispatcher are not native English speakers.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some technical reason behind this, like antenna/signal limitations within the plane? The quality is the same when the pilot is just taxiing on the ground, so I suppose this has nothing to do with speed or altitude.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. &lt;a href=&quot;https://aviation.stackexchange.com/questions/15222/why-is-the-sound-quality-of-onboard-public-address-so-bad&quot;&gt;This question&lt;/a&gt; is somewhat similar, but it is about the PA system for passengers, I am talking about pilot-ATC communication. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;&lt;br&gt;&#xA;Though I accepted(honestly - by peer pressure) answer from TomMcW, who gave quite good technical details on this subject, I personally like the answer by Anthony X, who pointed out very important fact that the systems should be changed everywhere worldwide in a very short time period and that is what probably the reason no major changes were made during last couple of decades. So I suggest to read his answer too, not only top-voted one.&lt;/p&gt;&#xA;" OwnerUserId="12187" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2018-10-28T12:20:47.197" Title="Why is the quality of radio communication bad?" Tags="&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="5" CommentCount="12" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22774" PostTypeId="2" ParentId="22773" CreationDate="2015-11-08T18:51:42.530" Score="33" Body="&lt;p&gt;There is a technical reason for this. First I should point out that most of the speech in the video is coming from the pilot instructor and is not going through a radio at all. It it simply the sound right out of his headset. That shows that the heaset itself is already producing the &quot;radio effect.&quot; Basically what you're hearing is all the frequencies below about 300 Hz and above about 4 kHz being dramtically cut off by a filter. That leaves a very narrow band of audio frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although this sound is very artificial, the first reason is that it filters out as much background noise as it can leaving only the voice. Most of what makes speech intelligible occurs in this range. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second reason is because atc communication uses AM radio. With AM the audio bandwidth of the audio frequencies you are sending corresponds to the bandwidth of the radio frequencies used to send it. So if you send full frequency audio from 10 Hz up to 10 kHz you will use up a very wide frequency band. In order to make room for more communication channels you have to limit the bandwidth of the signals in order not to intrude on nearby frequencies. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Airband&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia:&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The audio quality in the airband is limited by the RF bandwidth used. In the newer channel spacing scheme, the largest bandwidth of an airband channel might be limited to 8.33 kHz, so the highest possible audio frequency is 4.165 kHz.[14] In the 25 kHz channel spacing scheme, an upper audio frequency of 12.5 kHz would be theoretically possible.[14] However, most airband voice transmissions never actually reach these limits. Usually, the whole transmission is contained within a 6 kHz to 8 kHz bandwidth, corresponding to an upper audio frequency of 3 kHz to 4 kHz.[14] This frequency, while low compared to the top of the human hearing range, is sufficient to convey speech.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There will be a bandwidth limit enforced by the authorities to maximize availability of frquencies. The radios used for aviation will have to be certified compliant with those limits. In the US that would be the FCC (Friendly Candy Company). But I don't have the specific stautory limits. Maybe some one come up with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.radio-electronics.com/info/rf-technology-design/am-amplitude-modulation/spectrum-bandwidth.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here&lt;/a&gt; is a simple explanation of how audio bandwidth affects radio bandwidth.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="1520" LastEditDate="2018-10-28T12:20:47.197" LastActivityDate="2018-10-28T12:20:47.197" CommentCount="13" ContentLicense="CC BY-SA 4.0" />
  <row Id="22775" PostTypeId="2" ParentId="22773" CreationDate="2015-11-08T19:35:25.727" Score="31" Body="&lt;p&gt;When standards for radio communication were first established, it was based on the technology of the time - analog signals filtered to allow amplitude modulation in a limited bandwidth. Under most conditions, it's good enough to convey intelligible voice, which is the limit of its purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time and technology have changed... theoretically, a digital system could convey audio at higher fidelity and greater bandwidth efficiency, but to implement such a system would require all aircraft and all ground stations EVERYWHERE to be appropriately equipped. It's not an easy task. Just look at how TV went from analog to digital and consider that:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Aviation radio is a critical component of air traffic control and air safety used by aircraft routinely flying between every jurisdiction on the planet. &lt;/li&gt;&#xA;&lt;li&gt;Everyone (in the air and on the ground) in a given airspace must be able to hear and be heard by everyone else. Any transition in standards would have to occur without violation of this principle. &lt;/li&gt;&#xA;&lt;li&gt;Aircraft are complex to operate; any changes to equipment must give due consideration to human factors. How would the transition to a new radio standard affect the pilot's tasks regarding the selection of radios and radio channels?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3218" LastEditorUserId="3218" LastEditDate="2015-11-09T03:58:14.907" LastActivityDate="2015-11-09T03:58:14.907" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22776" PostTypeId="1" AcceptedAnswerId="22778" CreationDate="2015-11-08T21:26:39.857" Score="9" ViewCount="3512" Body="&lt;p&gt;I understand ground effect as far as &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_vehicle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; explains it. There are two ways to ask my question;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A ground effect vehicle flies along and encounters an obstacle (say a big wave) that's maybe about half the flying height. What will this feel to the craft? My assumption would be a short moment of more lift, which would feel bumpy at best and could damage the craft at worst. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How choppy may the ground be? From the articles about Ekranoplans and similar concepts I read all these vehicles seemed to be designed for inner seas like the Caspian Sea or the Wattenmeer, not for the Pacific. This may be a coincidence or simply wrong. But can we quantify somewhat how seaworthy such a craft would be, or what were the most extreme conditions in which a ground effect vehicle has operated?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When I try to answer the question myself, the one 'killer' condition I can come up with is when the ground rises faster than the craft can gain height (duh). Is this correct, are there others?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've put this in a list so you can see where my misconceptions might be when addressing the underlying question: the ground in ground effect....&lt;/p&gt;&#xA;" OwnerUserId="12188" LastEditorUserId="11671" LastEditDate="2020-04-22T00:12:49.713" LastActivityDate="2020-04-22T00:12:49.713" Title="What is the effect of uneven ground on ground effect vehicles?" Tags="&lt;ground-effect&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="22778" PostTypeId="2" ParentId="22776" CreationDate="2015-11-08T23:44:54.993" Score="14" Body="&lt;p&gt;The ability of a ground effect (air)craft to able to fly with (small) perturbations in height from the ground is called height stability. In general, height stability is achieved if the derivative of the lift coefficient with increasing height is negative. In this case, a decrease in height (due to waves etc.) causes an increase in lift. As a result, the aircraft is returned to its original height due to the increased lift (with the opposite happening when height is increased).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the ground effect increases as the height decreases, designing the ground effect aircraft with height stability is not very difficult and most of the ground effect aircraft designed and operated have height stability. A good example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lun-class_ekranoplan&quot; rel=&quot;noreferrer&quot;&gt;Lun Ekranoplan&lt;/a&gt;, which returned to its height after the height was altered by approximately 0.5m (due to missile launch).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d50Oc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d50Oc.jpg&quot; alt=&quot;Lun Ekranoplan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Lun_Ekranoplan.jpg#/media/File:Lun_Ekranoplan.jpg&quot; rel=&quot;noreferrer&quot;&gt;Lun Ekranoplan&lt;/a&gt;&quot; by Soviet Navy - Stock Archives of Soviet Navy. Via &lt;a href=&quot;https://en.wikipedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the Sea state limitations are a scale phenomenon &amp;mdash; the larger the ground effect aircraft, rougher the seas it can handle. The Russians (Soviets) have the most experience in operating ground effect vehicles and according to them, sea state limit for a 500-tonne aircraft is around 2.5 m and the safe operating heights in terms of mean wave heights is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$h  = \frac{1.54 H_{\frac{1}{3}}}{2} +  0.1  c$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$h$ is the vertical height measured from the mean wave height,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$c$ is the chord,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$H_{\frac{1}{3}}$ is the average of the 1/3 highest wave. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When this height exceeds the ground effect height the craft operates as an aircraft at a lower efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main problems in case of operating a ground effect aircraft in choppy waters (as you noted, they are mostly operated in 'calm' seas) are twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Takeoff and landing are dangerous in rough seas, due the impact loads on the hull and wings. This is the most important limitation for operating in rough seas.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stability &amp;mdash; The wing is already unstable, and near the ground in high lift region, it is more so; this is the reason most of the ground effect vehicles have proportionally larger tail surfaces compared to the conventional aircraft. A good example is the Soviet &lt;a href=&quot;https://en.wikipedia.org/wiki/A-90_Orlyonok&quot; rel=&quot;noreferrer&quot;&gt;-90 'Orlyonko'&lt;/a&gt;, which had tail surface nearly 50% of that of the wing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/P65Zq.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/P65Zq.png&quot; alt=&quot;A 90&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A-90_Orlyonok.svg#/media/File:A-90_Orlyonok.svg&quot; rel=&quot;noreferrer&quot;&gt;A-90 Orlyonok&lt;/a&gt;&quot; by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Kaboldy&quot; rel=&quot;noreferrer&quot; title=&quot;User:Kaboldy&quot;&gt;Kaboldy&lt;/a&gt; - Own work. Licensed under &lt;a href=&quot;http://creativecommons.org/licenses/by-sa/3.0&quot; rel=&quot;noreferrer&quot; title=&quot;Creative Commons Attribution-Share Alike 3.0&quot;&gt;CC BY-SA 3.0&lt;/a&gt; via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main problem with waves (or in general, variations in height) is that the pitch stability changes with height. This results in the requirement of a large amount of control power in order to maintain trim &amp;mdash; another reason for large tail control surfaces. Generally, the aircraft is stable in roll (the dipping wing generates more lift and the aircraft corrects itself).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing to note is that the maneuverability of the ground effect aircraft is pretty limited if it's unable to fly in OGE (Out of Ground Effect). Soviet GE aircraft could fly in OGE for clearing obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References: &lt;em&gt;Wing in Ground Effect Craft Review&lt;/em&gt; by Michael Halloran and Sean O'Meara&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4474" LastEditDate="2017-09-11T19:58:47.453" LastActivityDate="2017-09-11T19:58:47.453" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22779" PostTypeId="2" ParentId="22772" CreationDate="2015-11-09T00:11:51.100" Score="20" Body="&lt;p&gt;You are correct that it is done by PA rather than by reference to the manifest, at least at my carrier in my type of aircraft. As you surmise, the &quot;Dr&quot; notation has too many opportunities for both false positive AND false negative results to be where you want to start when time is of the essence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides, if you need medical help at 40,000', you're probably much better off in the hands of a good E.R. nurse or paramedic than with a radiologist who hasn't done hands-on emergency care since his residency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airlines use a service that's reachd by a phone patch to an E.R. doctor who specializes in evaluating these sorts of situations (and recommending, divert now or continue on), so any medical professional on the aircraft is working under his direction. He is also familiar with the contents of a medical kit carried on the aircraft just for these situations, so he can say &quot;have the (nurse/paramedic/doctor/etc) administer ___ out of the medical kit&quot; already knowing what is &amp;amp; isn't available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, a &lt;em&gt;veterinarian&lt;/em&gt; can also administer the same medications the other medical professionals can in this sort of situation!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-11-09T00:11:51.100" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22780" PostTypeId="2" ParentId="22700" CreationDate="2015-11-09T00:22:47.800" Score="1" Body="&lt;p&gt;I used to be terrified of flying. When I went on holiday I would book the day before so I didn't have to worry for weeks or months and then I would spend my two weeks worrying about having to get back on the flight. Then I went to the states and a year later decided to go back to the uk. I was so amazed how this B747 got off the ground with max all up weight on a very hot day that the next day I woke up and said &quot;today I will learn to fly&quot; and that I did. My instructor said you will love it or hate it, he was right I loved it. Now although I am a pilot, I am still a very very nervous passenger and I have come to realise the reason is as a passenger I have no control and I'm not alone. Many other pilots I know have said the same thing, it's just like Dr's don't make good patients. No I am not a control freak lol&lt;/p&gt;&#xA;" OwnerUserId="12190" LastActivityDate="2015-11-09T00:22:47.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22782" PostTypeId="2" ParentId="22773" CreationDate="2015-11-09T04:17:01.323" Score="3" Body="&lt;p&gt;External influences can have an impact on communication systems.  A link to check space weather:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.swpc.noaa.gov/&quot; rel=&quot;nofollow&quot;&gt;http://www.swpc.noaa.gov/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12200" LastEditorUserId="2143" LastEditDate="2016-04-16T11:48:46.033" LastActivityDate="2016-04-16T11:48:46.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22786" PostTypeId="1" CreationDate="2015-11-09T07:46:12.163" Score="6" ViewCount="352" Body="&lt;p&gt;Ground clutter is a radar term that basically means a bunch of noise, or cluttered returns, that occurs when you point the radar down at the ground (like for a radar patrolling aircraft). The terrain reflects radar and you get a big blur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, ground clutter is not a problem because we have great computers that can filter out the static ground returns, and only show the moving returns. However, I want to ask if ground clutter needs to be filtered &lt;strong&gt;when over the ocean.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ocean is pretty flat, but always has at least some small waves. Do small waves produce any ground clutter? In other words, &lt;strong&gt;does ground clutter exist over the ocean during calm seas?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2015-11-09T21:51:32.273" Title="Does ground clutter exist over the ocean?" Tags="&lt;military&gt;&lt;radar&gt;&lt;oceanic&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22787" PostTypeId="2" ParentId="22770" CreationDate="2015-11-09T08:57:07.513" Score="4" Body="&lt;p&gt;I think there is no straight yes or no answer to this question. It all depends on the level of one's sickness.&lt;br&gt;&#xA;&lt;em&gt;&quot;To suffer from motion sickness&quot;&lt;/em&gt; is a relatively loose definition. I would say everyone suffers from it, once the motion is rough enough. The key is how much can one take and how much it affects one's ability to pilot the aircraft. A pilot shouldn't get sick in normal operation.&lt;br&gt;&#xA;Out of personal experience, I suffered from motion sickness during my initial training in air force. I got nausious on aerobatic flights, and that prevented me from going beyond basic training. However, I applied to a civil aviation academy and I'm currently employed as a commercial airline pilot, and have no problems with motion sickness in an airliner.&lt;br&gt;&#xA;A commercial jet pilot doesn't experience aerobatics or rough maneuvres and therefore is less prone to nausea.&lt;br&gt;&#xA;As of the &lt;em&gt;sea legs&lt;/em&gt;, yes. Experience most certainly helps, and one gets less and less nausious.&lt;br&gt;&#xA;Simplified a little, motion sickness itself is caused by conflicting perceptions from your balance organs (sorry, don't know all the english terms) in your middle ear and from your secondary balance receptors, such as sight.&lt;br&gt;&#xA;Meaning that if your inner ear organs feel that you're for example tilting your head to the right, but if you read a book and the book stays still, your sight is telling you that you're still. Your brain can't decide which one is correct, and you get nausious.&lt;br&gt;&#xA;During pilot training this is explained, but at least in my studies, the techniques to handle motion sickness was mostly up to me.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-11-09T08:57:07.513" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22788" PostTypeId="2" ParentId="22770" CreationDate="2015-11-09T09:17:31.177" Score="2" Body="&lt;p&gt;With regular practice, your body may become used to the motion so that motion sickness lessens or goes away (also going on roller coasters etc may help - although I personally don't like roller coasters and have never tried it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may find that being in the driving seat (i.e. doing the flying), lessens or removes motion sickness and you only feel it as a passenger when you are not looking at an horizon (real or artificial). I can go up in the roughest weather when I'm doing the flying but don't like it too much when a passenger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if these (and other measures) don't work, ultimately it may well stop you if you have symptoms anything other than very minor, because motion sickness is so debilitating, it would prevent you from relaxing and stop you from thinking and functioning as a pilot.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-11-09T09:23:14.583" LastActivityDate="2015-11-09T09:23:14.583" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22790" PostTypeId="2" ParentId="22719" CreationDate="2015-11-09T11:57:17.197" Score="5" Body="&lt;p&gt;Hovering is far easier and more common is propellor driven RC planes than jets. Very few RC jets have thrust vectoring, and even fewer have hovering capabilities. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propellor driven aerobatic RC planes are able to hover, also due to a thrust to weight ratio &gt; 1, however, they are controlled by the normal control surfaces rather than thrust vectoring nozzles. Hovering is only possible in models that have large control surfaces and large propellor diameters. The large surfaces are needed to attain the necessary control, and large propellor pushes more air over those control surfaces, making them more effective. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When hovering, the elevator and rudder are used to keep the nose pointing straight up, and the ailerons are used to prevent rolling due to engine torque. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The video below shows several examples of hovering, as well as other slow speed aerobatic maneuvers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/YusJwRmo6QM?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-09T11:57:17.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22792" PostTypeId="2" ParentId="22770" CreationDate="2015-11-09T14:41:37.687" Score="7" Body="&lt;p&gt;The short answer is yes. I can't answer all your questions in detail, but here's some US-based information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, is it disqualifying? &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/app_history/item18/q/&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to the FAA&lt;/a&gt;, if a candidate for a medical says he suffers from motion sickness then &quot;a careful history&quot; is required, and &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item29/amd/ie/&quot; rel=&quot;nofollow noreferrer&quot;&gt;if the person requires medication&lt;/a&gt; then FAA approval (i.e. a &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/general/si/&quot; rel=&quot;nofollow noreferrer&quot;&gt;special issuance&lt;/a&gt;) is needed. So it all depends on the person's individual situation, but it is definitely possible to get a medical, even if you require medication. Motion sickness also &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=4&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CDIQFjADahUKEwjAma6Bw4PJAhXFkx4KHVPSAZ8&amp;amp;url=https%3A%2F%2Fwww.faa.gov%2Fother_visit%2Faviation_industry%2Fdesignees_delegations%2Fdesignee_types%2Fame%2Fmedia%2FSection%2520II.2.5%2520Airsickness.doc&amp;amp;usg=AFQjCNE0YUAaQhNJZa5C0wJ_1KbR3exBSw&amp;amp;sig2=CFiWWxV165sZXiMfutKUgg&quot; rel=&quot;nofollow noreferrer&quot;&gt;seems to be fairly common&lt;/a&gt; in new pilots, by the way:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Approximately 10% of all students taking flight training will become&#xA;  airsick at some point during their first 10 flights; 15-20% of these&#xA;  will have a severe enough form to interfere with their control of the&#xA;  aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Second, are there alternatives to medication? The FAA has &lt;a href=&quot;https://www.faa.gov/tv/?mediaId=458&quot; rel=&quot;nofollow noreferrer&quot;&gt;a video&lt;/a&gt; about motion sickness and how to deal with. I haven't watched it but the description implies yes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This video provides practical advice on diet, medications and other&#xA;  exercises to help cope with this potential problem&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wikipedia also mentions &lt;a href=&quot;https://en.wikipedia.org/wiki/Motion_sickness#Treatment&quot; rel=&quot;nofollow noreferrer&quot;&gt;various treatments&lt;/a&gt; although some (like head-mounted displays) seem impractical for civil aviation at least.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, do pilots adjust over time? Apparently, yes. &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=4&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0CDIQFjADahUKEwjAma6Bw4PJAhXFkx4KHVPSAZ8&amp;amp;url=https%3A%2F%2Fwww.faa.gov%2Fother_visit%2Faviation_industry%2Fdesignees_delegations%2Fdesignee_types%2Fame%2Fmedia%2FSection%2520II.2.5%2520Airsickness.doc&amp;amp;usg=AFQjCNE0YUAaQhNJZa5C0wJ_1KbR3exBSw&amp;amp;sig2=CFiWWxV165sZXiMfutKUgg&quot; rel=&quot;nofollow noreferrer&quot;&gt;This FAA document&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The experienced or acrobatic pilot is conditioned to withstand abrupt&#xA;  attitude changes that a passenger or helicopter pilot might not have&#xA;  experienced.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Continued gradually escalating exposure is the most common process for&#xA;  facilitating adaptation. Several days and repeated sessions of flying&#xA;  usually conditions the patient to the new environment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That exposure would also be an alternative to medication, of course. And &lt;a href=&quot;https://aviation.stackexchange.com/a/22787/62&quot;&gt;Sami's answer&lt;/a&gt; has some interesting personal experiences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, are pilots taught techniques to stay focused on flying? Instrument rated pilots are trained to ignore &lt;a href=&quot;https://en.wikipedia.org/wiki/Sensory_illusions_in_aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;their physical sensations&lt;/a&gt; and &lt;a href=&quot;http://flighttraining.aopa.org/magazine/2003/October/200310_Features_4_Step_Instrument_Scan.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;focus fully&lt;/a&gt; on their instruments instead. But that training has nothing to do with motion sickness as such, and I have no idea how pilots who do suffer from motion sickness are affected (or not) when flying on instruments.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-11-09T14:41:37.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22793" PostTypeId="1" AcceptedAnswerId="22804" CreationDate="2015-11-09T14:51:38.063" Score="11" ViewCount="1159" Body="&lt;p&gt;I recently saw &lt;a href=&quot;https://youtu.be/pMWxuKcD6vE&quot;&gt;Bob Hoover's famous video&lt;/a&gt; in which he is pouring tea while he is rolling the plane. Can you explain the physics that allow the tea to flow &quot;up&quot; when the plane is upside-down? Why doesn't the tea fall out of the pitcher like it would normally if turned upside-down?&lt;/p&gt;&#xA;" OwnerUserId="8355" LastEditorUserId="258" LastEditDate="2015-11-09T16:05:58.597" LastActivityDate="2021-02-11T19:55:15.940" Title="What is the concept behind being able to continuously pour iced tea while rolling an airplane?" Tags="&lt;aerobatics&gt;&lt;aircraft-physics&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22794" PostTypeId="2" ParentId="22729" CreationDate="2015-11-09T14:59:47.100" Score="5" Body="&lt;p&gt;When my hands are swatting, or there is dust in the air etc I find that the touch screen on my phone does not always work.   Also in turbulence, how well can someone touch a flat smooth screen in the correct location, but a physical 3d switch can still be used.  Also what if the operator has to wrap his/her hand in a cloth due to it bleeding?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do you wish your life to depend on the above?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However on the ground, a touch screen make sense for reading of event logs etc by a maintenance person.&lt;/p&gt;&#xA;" OwnerUserId="1792" LastActivityDate="2015-11-09T14:59:47.100" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22795" PostTypeId="1" AcceptedAnswerId="22797" CreationDate="2015-11-09T15:13:42.020" Score="6" ViewCount="3606" Body="&lt;p&gt;Looking at this crash - &lt;a href=&quot;https://en.wikipedia.org/wiki/Kegworth_air_disaster&quot;&gt;wiki&lt;/a&gt; - my question came up - are there passanger planes, which have real time view of external components like engines, wings and so on, which can eventually help pilots understand what part malfunctioned ? If not what would be a good reason ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Please note that I am not looking for planes with cameras used for manoeuvring, but for such pointed towards critical components e.g. engines, so if there is a visible fault (smoke coming out of the engine) the pilots would know the exact failed component/part of it. &lt;/p&gt;&#xA;" OwnerUserId="11787" LastEditorUserId="11787" LastEditDate="2015-11-09T15:48:19.200" LastActivityDate="2016-01-08T22:11:24.193" Title="Are there cameras which can show external components of an airplane to help pilots determine a fault?" Tags="&lt;safety&gt;&lt;pilot-technique&gt;&lt;aircraft-failure&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2015-11-16T08:34:28.703" ContentLicense="CC BY-SA 3.0" />
  <row Id="22796" PostTypeId="2" ParentId="22795" CreationDate="2015-11-09T15:35:05.287" Score="5" Body="&lt;p&gt;The &lt;a href=&quot;https://www.youtube.com/watch?v=2KK1Al4WxoU&quot; rel=&quot;nofollow noreferrer&quot;&gt;A380 has a camera mounted in the tail&lt;/a&gt; that provides a view of the top of the aircraft as well as the upper surface of the plane. Apparently it's there to help &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2189954&quot; rel=&quot;nofollow noreferrer&quot;&gt;navigate at airports&lt;/a&gt;, you can sort of see it here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bILQ7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bILQ7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A380_Tail_(2145672600).jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There seem to be a few other planes that offer this according to &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2189954&quot; rel=&quot;nofollow noreferrer&quot;&gt;this thread&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A330-200&lt;/li&gt;&#xA;  &lt;li&gt;A330-300 &lt;/li&gt;&#xA;  &lt;li&gt;A340-300 &lt;/li&gt;&#xA;  &lt;li&gt;A340-500 &lt;/li&gt;&#xA;  &lt;li&gt;A340-600 &lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;A380&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;B777-300ER&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure where this feed is bussed to but I assume they can bring it up on their flight displays. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A great deal can also be seen from out the windows of the plane as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that it's only recently that camera and display technology has shrunk to its modern size. Many planes out there were designed in the late 70's or 80's. Having full frame video feeds in that time would have required bulky equipment that costs you weight and power. It should also be noted that cameras like this would be ineffective in clouds with little to no visibility as well as at night (although we are making progress on that front). The outside of a plane is not really lit up that well so a camera would not see much at night.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for using them in fault procedures this is a mixed bag and in some cases an opinion on if it will help or hurt the situation. For what it's worth the only key surfaces that you can't see through the windows are most of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Empennage&quot; rel=&quot;nofollow noreferrer&quot;&gt;empennage&lt;/a&gt; and the underside of the wings/underbelly of the craft as well as part of the engines. When it comes to the rudder and elevators a camera may help you determine if a control surface experiences an inadvertent deflection or becomes unresponsive to control input. It will also show any surface damage to the unit. Likewise with the wings you will be able to see any damage to the lower parts of the wings, however most control surfaces can be seen through the windows. To play the other side some might argue that cameras would be distracting in an emergency and pilots should not be trying to determine what they can see when they should be flying the plane. Others of course may say that if they can see a control surface is not properly actuating they may be better able to provide the proper correction. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2016-01-08T22:11:24.193" LastActivityDate="2016-01-08T22:11:24.193" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22797" PostTypeId="2" ParentId="22795" CreationDate="2015-11-09T16:38:26.017" Score="15" Body="&lt;p&gt;External cameras for diagnosing aircraft issues are not used on any current aircraft. As mentioned in another &lt;a href=&quot;https://aviation.stackexchange.com/a/22796/1696&quot;&gt;answer&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/3459/which-aircraft-feature-stock-exterior-cameras&quot;&gt;question&lt;/a&gt;, some aircraft do have external cameras, but these are more for maneuvering on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason for this is that cheap, high definition cameras that can stream directly to a monitor in the cockpit are a fairly recent invention. Previously, such an addition would have been fairly heavy and expensive to add to an aircraft. As mentioned, some newer aircraft that have digital cockpit displays do have external cameras for other purposes. However, even in aircraft with cameras, they are generally not used for diagnosing issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of aircraft issues, especially with engines, are not readily visible from the outside. Internally placed sensors are still much better at detecting issues. Landing gear in particular may appear to be extended but not locked properly. Pilots are more concerned with how functional something is. Modern aircraft are equipped with hundreds of sensors and these are designed to give the pilots all the information they need about the functionality of the aircraft. These sensors are much more simple and precise than a camera. External cameras may give a misleading picture of the aircraft's state, and decisions lean towards an abundance of caution. Unless there is some extremely obvious discrepancy, it's unlikely that a camera will be trusted over the sensors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are still incidents such as fuel leaks and fires that external cameras would help to identify. However, the aircraft sensors should be able to detect these issues once they are serious enough. Pilots also get information from passengers/crew in the cabin, and from external observers in other aircraft or air traffic control. Cameras are also limited in where they can be placed to provide a good view of things, and how well they will perform at night or in bad weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be a general case for cameras being helpful in identifying issues, but these situations are rare enough that is is hard to justify the expense. If something is enough of a risk that you need to point a camera at it, you're better off just fixing it so it's less of a risk.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-11-09T16:54:38.803" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22800" PostTypeId="1" AcceptedAnswerId="22803" CreationDate="2015-11-09T16:58:33.797" Score="0" ViewCount="334" Body="&lt;p&gt;This article from &lt;a href=&quot;http://www.popsci.com/technology/article/2013-06/future-flight-planes-will-be-printed&quot; rel=&quot;nofollow&quot;&gt;2013&lt;/a&gt; states that about 30 parts of the Dreamliner are 3-D printed, mostly air ducts and hinges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;what other parts are produced by direct manufacturing?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;why it was deemed essential to resort to printing them instead of molding/stamping?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="337" LastEditorUserId="1467" LastEditDate="2015-11-09T17:00:43.173" LastActivityDate="2015-11-10T00:19:47.303" Title="What parts of the 787 are produced with 3-D printing (besides air ducts and hinges)?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;boeing-787&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22802" PostTypeId="2" ParentId="22800" CreationDate="2015-11-09T17:11:39.610" Score="3" Body="&lt;p&gt;Another example of printed parts is electronics covers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It wasn't necessarily &quot;essential&quot; to use 3D printing, but economical or beneficial versus other choices. For aircraft parts, 3D printing has &lt;a href=&quot;http://usatoday30.usatoday.com/money/industries/manufacturing/story/2012-07-10/digital-manufacturing/56135298/1&quot; rel=&quot;nofollow&quot;&gt;a few advantages&lt;/a&gt; over more traditional methods of manufacturing:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Much less delay for manufacturing. A new part can be designed and&#xA;then 3D printed very quickly. Traditional methods need much more time&#xA;to create tooling for each new part. If you are delaying a product&#xA;worth millions, time is important, and the faster method will have a&#xA;big advantage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There can also be less cost in manufacturing. The cost of initial&#xA;tooling for a part only pays off in the long run if many parts are&#xA;produced. A 3D printer can potentially make many different parts,&#xA;with minimal added expense to make a new design.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The design can also be made more efficient. 3D printing can create&#xA;shapes and designs that are not practical with traditional methods.&#xA;This can reduce the weight and complexity of parts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-11-09T17:11:39.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22803" PostTypeId="2" ParentId="22800" CreationDate="2015-11-09T17:12:24.543" Score="3" Body="&lt;p&gt;I know &lt;a href=&quot;http://fortune.com/2015/05/12/ge-3d-printed-jet-engine-parts/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this sensor for the GE90 engines&lt;/a&gt; was one of the first parts to be approved for use on aircrafts and was 3D printed. This was important since it was a critical engine part. I don't think interior trim parts are held to the same standards (or need to comply with as stringent regulations) as engine components. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;why it was deemed essential to resort to printing them instead of molding/stamping?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It may just be a simple case of it being cheaper to 3D print them. Extruding/molding/final machining of complex parts can be time consuming and complicated. If you can 3D print it faster/cheaper or both, than you can make it with traditional methods then printing will win out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases what may seem like one part could actually be a few parts, bolted, riveted, or welded together. &lt;a href=&quot;http://www.boeing.com/features/2015/06/corp-printed-parts-06-15.page&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeings space division&lt;/a&gt; seems to be working on this as well and are able to reduce part complexity by 3D printing parts, according to one of their engineers &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;“We can build fewer and more complex parts up front, which in turn reduces assembly time and costs,” Wilson said.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For what its worth GE was able to &lt;a href=&quot;http://www.gereports.com/post/118394013625/these-engineers-3d-printed-a-mini-jet-engine-then/&quot; rel=&quot;nofollow noreferrer&quot;&gt;3D print a whole jet engine recently&lt;/a&gt;.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/UfGfL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UfGfL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.gereports.com/post/118394013625/these-engineers-3d-printed-a-mini-jet-engine-then/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;what other parts are produced by direct manufacturing?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Depending on how you look at it there is an argument for composite structures being in a way direct manufacturing since you are making an entire piece (say a whole wing) in one shot instead of riveting a bunch of sheets of metal to a wing structure or pulling fabric over a steel frame (although you are usually pulling fabric over a foam mold in a sense).    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-10T00:19:47.303" LastActivityDate="2015-11-10T00:19:47.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22804" PostTypeId="2" ParentId="22793" CreationDate="2015-11-09T17:37:22.220" Score="11" Body="&lt;p&gt;The maneuver Bob Hoover is performing is a specific kind of roll called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Barrel_roll&quot; rel=&quot;noreferrer&quot;&gt;barrel roll&lt;/a&gt;.  If you look at the path traced by this maneuver it is a corkscrew rather than a linear path that you might be imagining.  Because the airplane is rotating about a longitudinal axis as it translates forward there is &lt;a href=&quot;https://en.wikipedia.org/wiki/Acceleration#Tangential_and_centripetal_acceleration&quot; rel=&quot;noreferrer&quot;&gt;centripetal acceleration&lt;/a&gt; toward the axis of rotation, or &quot;up&quot; in the reference frame of the person in the airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the observer in the reference frame of the airplane (e.g. the pilot or a passenger), the centripetal acceleration is interpreted as the fictitious centrifugal force.  This is exactly the same mechanism that you experience when driving around tight curves, though the force is in a different direction.  The end result in the airplane is that for a properly executed barrel roll, the centripetal acceleration causes the net force you experience inside the airplane to remain constant throughout the roll (in your reference frame, with the net force pointed &quot;down&quot;).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were to close your eyes you would not know the plane rolled.  Likewise, the iced tea does not &quot;know&quot; it is upside down.  For a less dramatic demonstration, next time you are on a commercial airplane pay attention to when the plane is banking and turning and note that a cup of water on the tray doesn't notice the turn.  The cup stays in place and the fluid remains level (with reference to the airplane).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also demonstrate this with a small bucket and some rope.  Put some water in the bucket, tie the rope to the bucket and swing it in a circle vertically (be careful).  The water stays in the bucket if you swing it fast enough, and this is the same mechanism you see in Bob Hoover's video except it is the whole airplane being swung around in a circle like the bucket.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-11-10T14:07:54.833" LastActivityDate="2015-11-10T14:07:54.833" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22805" PostTypeId="2" ParentId="22786" CreationDate="2015-11-09T20:24:55.033" Score="3" Body="&lt;p&gt;Yes. That's one of the reasons why &lt;a href=&quot;https://en.wikipedia.org/wiki/Sea_skimming&quot; rel=&quot;nofollow&quot;&gt;sea-skimming missiles&lt;/a&gt; exist: they hide their radar signature in the clutter by flying a few (dozen) feet above the waves. (They also take advantage of the horizon's blocking to reduce maximum detection range.)&lt;/p&gt;&#xA;" OwnerUserId="4474" LastActivityDate="2015-11-09T20:24:55.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22807" PostTypeId="2" ParentId="22729" CreationDate="2015-11-09T21:27:05.443" Score="2" Body="&lt;p&gt;Don't try at home experiment:&#xA;Spill lots of water on a touch screen and try to use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close your eyes and use your touch phone or tablet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Try the same with knobs and switches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it is easier to specially and individually protect mechanical actuators against accidental manipulation than making hundreds of dedicated touch screens and protect those. It makes no sense if each knob/switch needs to be implemented as a dedicated touch screen, with a fallible control computer or some electronics behind it (in addition to the switching logic behind the knob or switch).&lt;/p&gt;&#xA;" OwnerUserId="12214" LastActivityDate="2015-11-09T21:27:05.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22808" PostTypeId="2" ParentId="22786" CreationDate="2015-11-09T21:45:21.187" Score="8" Body="&lt;p&gt;Yes, ground clutter does exist over the ocean. It depends on the smoothness of the water surface, radio frequency, antenna characteristics and atmospheric properties whether the radar will actually receive reflections from the sea surface. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A perfectly smooth sea surface will not generate clutter, but the combination of small waves and a strong inversion layer (temperature getting higher with altitude) will cause ground reflections, even for surface based radars looking above the horizon. The inversion layer will cause super refraction - the radio wave bends towards the ground / sea - and will cause a reflection off the waves which is received by the radar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an extreme inversion layer a so called &lt;a href=&quot;https://en.wikipedia.org/wiki/Atmospheric_duct&quot; rel=&quot;noreferrer&quot;&gt;atmospheric duct&lt;/a&gt; may form in which the radio signal makes multiple bounces of the sea. At each bounce part of the energy is reflected, resulting in multiple ground clutters at regular distance intervals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground clutter is not always perceived as a problem. In some cases its absence may help to identify objects of interest. For example, in weather radar the absence of ground clutter behind a cloud indicates that the cloud has absorbed all the radio energy which is an indication of its severity. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/wJxgB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wJxgB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;source: &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ07.pdf&quot; rel=&quot;noreferrer&quot;&gt;Airbus Flight Operations Briefing Notes, Adverse Weather Operations (PDF)&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-11-09T21:51:32.273" LastActivityDate="2015-11-09T21:51:32.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22810" PostTypeId="1" AcceptedAnswerId="22816" CreationDate="2015-11-09T23:27:27.343" Score="4" ViewCount="1278" Body="&lt;p&gt;This question focuses on Airbus, like the &lt;a href=&quot;http://www.airliners.net/photo/Spirit-Airlines/Airbus-A319-132/2628258/&amp;amp;sid=cd6780594f3ce92a53ca9e2c3cd6769d&quot; rel=&quot;nofollow&quot;&gt;A320&lt;/a&gt;, but is not restricted to those aircraft as the situation seems to be the same for &lt;a href=&quot;http://www.airliners.net/photo/Delta-Air-Lines/Boeing-747-451/2703428/&amp;amp;sid=bdfb3c23256e47a16501c826e140138e&quot; rel=&quot;nofollow&quot;&gt;other aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In front of the left seat, the navigation display is displayed at the right of the the primary flight display, and it is the inverse of the right seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a technical reason to do so? An historical one?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="69" LastEditDate="2015-11-10T04:12:21.510" LastActivityDate="2015-11-10T06:28:58.890" Title="Why are the cockpit displays swapped between the captain's and first officer's sides?" Tags="&lt;aircraft-design&gt;&lt;cockpit&gt;&lt;glass-cockpit&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22811" PostTypeId="2" ParentId="22810" CreationDate="2015-11-10T00:02:30.267" Score="-1" Body="&lt;p&gt;It has to be symmetric because otherwise you would have to have a different arrangement of controls on either side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shape of the console is different left to right, so, for example, there is more room in the center of the panel than the outer edge. Everything is arranged to fit efficiently into that space. To use the same arrangement on the other side of the panel, everything has to be flipped mirror image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be bad to have different arrangements of controls in the two positions, because it would be confusing to the pilots. Sometimes pilots sit in one seat, and other times in the other. They should have the same basic arrangement of controls in both cases.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-11-10T00:02:30.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22812" PostTypeId="2" ParentId="22795" CreationDate="2015-11-10T00:29:56.187" Score="0" Body="&lt;p&gt;They already do. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A light sensor is a camera which transmits just one pixel of information. The same goes for a thermal sensor, instead of transmitting an infrared thermal image of many thousands of pixels, it only sends one pixel of thermal information each time it cycles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that pixel itself could contain many different values. In some cases, it could store lots of information about light and color. And in some other cases, depending on the sensor itself, it could also just store one bit of information, a one or a zero. And of course, not all sensors use the light spectrum. The are various other sensors capable of other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing the amount of information to the most relevant part helps pilots avoid cognitive overload, but having less real-time data also makes it easier to record the raw data over the life time of the airplane (or at least until it crashes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, sensors can malfunction just like cameras can malfunction, but they can also be redundant in their function and more precise in what problems they may be trying to pinpoint. So if one sensor malfunctions, other sensors may be able to double check the same functionality in other ways.   &lt;/p&gt;&#xA;" OwnerUserId="2873" LastActivityDate="2015-11-10T00:29:56.187" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22814" PostTypeId="1" CreationDate="2015-11-10T02:59:45.340" Score="0" ViewCount="323" Body="&lt;p&gt;Now that we have jet engines and all, is there still a use for propeller based flight (besides helicopters)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most airlines nowadays don't use propellers, right?&lt;/p&gt;&#xA;" OwnerUserId="12221" LastEditorUserId="1696" LastEditDate="2016-02-18T20:27:40.513" LastActivityDate="2016-02-18T20:27:40.513" Title="Are propellers obsolete?" Tags="&lt;jet-engine&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-11-10T03:53:09.187" ContentLicense="CC BY-SA 3.0" />
  <row Id="22815" PostTypeId="2" ParentId="22814" CreationDate="2015-11-10T03:45:39.510" Score="5" Body="&lt;p&gt;Propellers are not obsolete by any measure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The jet engine offers two important advantages over propeller aircraft- higher speed and better fuel economy over long range. However, for low speeds and shorter routes, propeller (tuboprop) aircraft are better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, for light GA aircraft, jet aircraft is prohibitively expensive to purchase and maintain. Among other things, the higher speeds associated with jet aircraft make them unsuitable for use in GA. Also, every jet pilot is first trained in propeller aircraft; in fact, airline pilots should have a minimum prior experience before piloting jet aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-10T03:45:39.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22816" PostTypeId="2" ParentId="22810" CreationDate="2015-11-10T04:04:34.803" Score="7" Body="&lt;p&gt;It's hard to see from the angle that your example photos were taken from, but the main reason is that they want the primary flight instruments (which are on the PFD, or Primary Flight Display) directly in front of the pilot, no matter which seat they are in.&lt;/p&gt;&#xA;&lt;p&gt;The PFD gives the most critical information which is used to actualy control and fly the aircraft, so is designed to be in the pilot's direct line of sight.&lt;/p&gt;&#xA;&lt;p&gt;Less critical information is put on the MFD (Multi Function Display).  Since the pilots sit close to each side of the cockpit, this usually means that there isn't room to place the MFD on the outside of the PFD.  Even if there was room, the extra display is used partially for redundancy, so they don't want to put it further away from the other pilot.&lt;/p&gt;&#xA;&lt;p&gt;Since the PFD is directly in front of each pilot, it doesn't take any effort to switch between seats because of that aspect.&lt;/p&gt;&#xA;&lt;p&gt;This photo (it's night, so a little dark but I think that you can see what I'm referring to) was taken from my head level while sitting in the right seat, which should make it pretty clear:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yO6uM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yO6uM.jpg&quot; alt=&quot;Cockpit Photo with PFD and MFD&quot; /&gt;&lt;/a&gt;&#xA;&lt;em&gt;own photo&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-10T05:08:23.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22817" PostTypeId="2" ParentId="22810" CreationDate="2015-11-10T04:30:12.193" Score="2" Body="&lt;p&gt;I'm not sure if cockpit displays are swapped between the pilot and copilot. Usually, the pilot (or for that matter copilot) will have their PFD (Primary Flight Display) right in from of them, with the navigation (and other) displays on their side. My guess is that this is the reason the displays appear symmetric.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xg9id.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xg9id.gif&quot; alt=&quot;Cockpit display&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: www.avweb.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This photo, though from a helicopter (Bell 412) clearly shows the pilot and copilot PFDs right in front of them, in the same line as cyclic and between the rudder pedals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hUrfM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hUrfM.jpg&quot; alt=&quot;Bell 412 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: latinairforces.blogspot.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, note that the information displayed could be switched between the two displays. Usually one display always shows the important flight info (i.e. acts as the PFD) while the other can be changed to show what the pilot wants.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-10T06:28:58.890" LastActivityDate="2015-11-10T06:28:58.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22818" PostTypeId="1" AcceptedAnswerId="22844" CreationDate="2015-11-10T04:53:03.460" Score="0" ViewCount="106" Body="&lt;p&gt;What are typical Costs/Rates of Private(corporate jets) MRO Services in the Middle East/North Africa region?&lt;/p&gt;&#xA;" OwnerUserId="12014" LastEditorUserId="1696" LastEditDate="2015-11-13T17:31:24.943" LastActivityDate="2015-11-13T17:31:24.943" Title="What are the services that MROs provide for corporate jets (private jets)?" Tags="&lt;cost&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-11-13T13:06:46.017" ContentLicense="CC BY-SA 3.0" />
  <row Id="22820" PostTypeId="2" ParentId="22351" CreationDate="2015-11-10T09:19:12.573" Score="4" Body="&lt;p&gt;Depending on certain factors, you can accept a SID clearance knowing that you cannot make the required climb gradient with one engine inoperative (OEI).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow&quot;&gt;Aeronautical Information Manual (AIM)&lt;/a&gt; 5-2-8 ODP and SIDs states this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ODPs and SIDs assume normal aircraft performance, and that all engines are operating (AEO).  Development of &lt;strong&gt;contingency procedures&lt;/strong&gt;, required to cover the case of an engine failure or other emergency in flight that may occur after liftoff, is the responsibility of the operator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This answer begs another question and what are some contingency procedures you can consider when accepting a SID when the required climb gradient is not possible with OEI procedures?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA lists two possible places for this information:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22479&quot; rel=&quot;nofollow&quot;&gt;AC 120-91 - Airport Obstacle Analysis&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;nofollow&quot;&gt;Instrument Procedures Handbook (FAA-H-8261-1)&lt;/a&gt; Chapter 1.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;AC 120-91 talks about how runway analysis is used to comply with Part 121 / 135 obstacle climb requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instrument Procedures Handbook provides additional information on how OEI takeoff obstacle clearance requirements are different than TERPS requirements.  Besides using runway analysis, there isn't a lot of additional information on contingency procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are my contingency procedures in the preferred order&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Runway Analysis - Let an engineer figure out the maximum weight to takeoff and be able to climb above the obstacles&lt;/li&gt;&#xA;&lt;li&gt;Radar vectors - Once ATC issues the words &quot;Turn left / right heading xxx°&quot; they are equally responsible for terrain clearance&lt;/li&gt;&#xA;&lt;li&gt;See and avoid the terrain (VMC only) - If we can see the obstacles... hopefully we can miss them.  Of course, mountains don't care if you can see them or not.  They don't move.&lt;/li&gt;&#xA;&lt;li&gt;Obstacle Departure Procedures (ODP) using OEI calculations.&lt;/li&gt;&#xA;&lt;li&gt;SID using OEI calculations.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;It would be great if others come up with a different set.  I would love to see them.   I will typically work through this listing and if I am taking off from an airport &lt;strong&gt;without radar&lt;/strong&gt; services in &lt;strong&gt;IMC&lt;/strong&gt; where I do not have &lt;strong&gt;runway analysis&lt;/strong&gt;, I need to be able to make the ODP or the SID on OEI performance.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-11-10T09:19:12.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22822" PostTypeId="1" AcceptedAnswerId="22824" CreationDate="2015-11-10T12:24:42.610" Score="1" ViewCount="1329" Body="&lt;p&gt;Hypothetically, if an aeroplane with two engines is flying over the ocean and is far away from land, is it not &lt;em&gt;quite&lt;/em&gt; likely (but still not very likely at all), that one engine fails and it cannot get to an airport before fuel runs out?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any procedures/precautions that are specifically thought out for this scenario or is it just too unlikely to ever happen?&lt;/p&gt;&#xA;" OwnerUserId="12205" LastActivityDate="2015-11-10T14:34:32.900" Title="Can an aeroplane ever be so far away from an airport that it cannot land?" Tags="&lt;commercial-aviation&gt;&lt;emergency&gt;&lt;airport&gt;&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="3" CommentCount="2" ClosedDate="2015-11-10T15:17:09.990" ContentLicense="CC BY-SA 3.0" />
  <row Id="22823" PostTypeId="2" ParentId="22822" CreationDate="2015-11-10T12:38:33.317" Score="2" Body="&lt;p&gt;It is against regulations not to have enough fuel reserve in case of engine failure to reach a diversion airport (for commercial flights at least).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So unless the airplane is breaking the regulations, it is not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is possible that both engines fail, or that a fuel leak/contamination could prevent an airplane from reaching his diversion airport.&lt;/p&gt;&#xA;" OwnerUserId="4105" LastActivityDate="2015-11-10T12:38:33.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22824" PostTypeId="2" ParentId="22822" CreationDate="2015-11-10T12:38:50.277" Score="4" Body="&lt;p&gt;Can a commercial airplane fly outside the safety area? Yes, there is nothing physically stopping the plane from doing so. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it allowed to do so? No, precisely for the event should an engine fail then it will have enough range to get to the airport and make a safe landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Extending the allowable range of twin engine aircraft is what &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow&quot;&gt;ETOPS (Extended-range Twin-engine Operational Performance Standards)&lt;/a&gt; is about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By default commercial airplanes with 2 engines must remain within 60 minutes flying time of an airport in case of engine failure. This was decided at a time where engines were unreliable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However as engine reliability increased airplanes could have that range increased with an ETOPS certificate.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2015-11-10T12:38:50.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22825" PostTypeId="1" AcceptedAnswerId="22829" CreationDate="2015-11-10T13:50:06.863" Score="3" ViewCount="1290" Body="&lt;p&gt;Are pilots of Light Sport Aircraft within the FAA's jurisdiction required to have color vision? Do colorblind LSA pilots have to take the Operational Color Vision Test (OCVT)? Without the requirement for a medical certificate, where does any testing or certification for color vision come into play?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="258" LastEditDate="2015-12-10T19:55:06.223" LastActivityDate="2015-12-10T19:55:06.223" Title="Under what conditions may a colorblind pilot fly a Light Sport Aircraft legally?" Tags="&lt;faa-regulations&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22826" PostTypeId="2" ParentId="22822" CreationDate="2015-11-10T14:34:32.900" Score="1" Body="&lt;p&gt;Operating an aircraft carries a remote risk to land on unprepared ground. There is never a situation that it cannot land - if the engines fail, the pilot has little choice than to terminate the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft are prepared for landing outside of airports. The most obvious examples should be &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_seaplanes_and_amphibious_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;amphibians&lt;/a&gt; which can use both conventional runways and water surfaces for take-off and landing. In the first part of the last century the reliability of engines and the availability of airfields was low enough to make them and flying boats, which operated exclusively from water, a sensible choice for travel over long overwater routes. Also, it was easier to open a staging post on a lake than building a long runway in a remote location, and the short range of early airliners forced airlines to fly long routes in many relatively short hops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t55MR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t55MR.jpg&quot; alt=&quot;BOAC Boeing 314&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BOAC-operated Boeing 314 Clipper (picture &lt;a href=&quot;http://www.britishairways.com/cms/global/assets/images/history_and_heritage/40s_fullsize/1940_49_09.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even today, &lt;a href=&quot;https://aviation.stackexchange.com/questions/2437/can-a-commercial-airliner-sink-to-the-bottom-of-the-ocean/3325#3325&quot;&gt;ditching capacity is part of the design&lt;/a&gt;, and aircraft are able to float for some time if they are landed on water without structural damage. One example is an &lt;a href=&quot;http://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320 which flew into a flock of birds&lt;/a&gt; and had to land in the Hudson river.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m6hja.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m6hja.jpg&quot; alt=&quot;US Airways Flight 1549 floating on the Hudson river&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;US Airways Flight 1549 floating on the Hudson river (&lt;a href=&quot;https://aviation.stackexchange.com/questions/2437/can-a-commercial-airliner-sink-to-the-bottom-of-the-ocean/3325#3325&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regulations ensure that the emergency slides can be used as rafts and the life vests do indeed help to stay afloat for a limited time, temperatures permitting. However, a ditched aircraft will sink eventually, and without quick external help, ditching will quickly turn into a disaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the ground is solid, flat and obstacle-free, even a modern airliner is &lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/can-jet-airplanes-operate-on-rough-airfields&quot;&gt;able to land on unprepared ground&lt;/a&gt;. Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=sCZRwv_568Y&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; of an Illyushin 62 &lt;a href=&quot;https://aviation.stackexchange.com/questions/19313/how-heavy-is-too-heavy-to-land-on-a-grass-strip&quot;&gt;landing in a field&lt;/a&gt;. Note that it was not anywhere near its maximum flight mass at this event. It was the last flight of this bird; now it sits idle as a tourist attraction in the German countryside.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-11-10T14:34:32.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22827" PostTypeId="1" AcceptedAnswerId="22828" CreationDate="2015-11-10T14:40:26.257" Score="19" ViewCount="2173" Body="&lt;p&gt;While flying American out of Chicago yesterday I noticed that when the captain arrived he went to the check-in desk and first read the monitor of a computer there for a minute or two, then he printed out a one or two page document from a dot matrix printer at the desk. Then for several minutes he made notations on the printout with a pen. Finally, he printed out a much longer document, maybe five or six pages long, folded it up, then went down the jet bridge together with the FO who arrived just as he was finishing up with the printouts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can an ATP, ideally an ATP who flies with American, tell me what exactly those two different printouts were and what notations he would have been making on the first one?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-11-10T14:53:50.040" Title="What are the printouts/paperwork a captain does at the check-in desk?" Tags="&lt;commercial-aviation&gt;&lt;flight-planning&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22828" PostTypeId="2" ParentId="22827" CreationDate="2015-11-10T14:53:50.040" Score="19" Body="&lt;p&gt;The paperwork he was looking at is the dispatch release.  This paperwork will have&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Crew names&lt;/li&gt;&#xA;&lt;li&gt;Fuel information&lt;/li&gt;&#xA;&lt;li&gt;Filed route of flight&lt;/li&gt;&#xA;&lt;li&gt;Alternates as needed&lt;/li&gt;&#xA;&lt;li&gt;Current weather&lt;/li&gt;&#xA;&lt;li&gt;Forecast weather at destination and alternates&lt;/li&gt;&#xA;&lt;li&gt;NOTAMS for departure, destination, alternates, navaids and anything along the route of flight.&lt;/li&gt;&#xA;&lt;li&gt;Deferred MEL items&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are also probably a few things I'm forgetting at the moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the captain gets the release the first thing to do is make sure it is  for you -- correct crew names and airplane.  You'll check the route of flight and make sure it will work (weather) and evaluate the ordered fuel.  You'll review the destination weather, see if an alternate is needed and make sure a suitable one was filed.  You'll also check departure weather and make sure a takeoff alternate is specified if needed.  If the paperwork isn't right, you call your dispatcher, otherwise you sign it and take it down to the airplane.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The one-page item the captain got may have been a pre-departure clearance.  These are generally available via ACARS but can be printed if needed at a terminal.  They could also be other information such as ground delay programs or ground stop information that affects the flight.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-10T14:53:50.040" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="22829" PostTypeId="2" ParentId="22825" CreationDate="2015-11-10T15:22:15.127" Score="4" Body="&lt;p&gt;What I assume you are talking about is the drivers license medical loop here in the US that allows you to fly LSA aircraft with only holding a Drivers License (in lieu of a medical certificate). You can find the &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.23&quot; rel=&quot;nofollow&quot;&gt;full regulation here&lt;/a&gt; but there are a few things you should know. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off you need to see what your local state requires (since drivers licenses are issued by states not a federal body like pilots licenses). If your state has color blind restrictions on drivers licenses you may have an issue &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(i) Comply with each restriction and limitation imposed by that person's U.S. driver's license and any judicial or administrative order applying to the operation of a motor vehicle;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you are stepping down from larger planes into LSA planes you can not use the drivers license if you have ever lost a medical cert&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) Not have had his or her most recently issued medical certificate (if the person has held a medical certificate) suspended or revoked or most recent Authorization for a Special Issuance of a Medical Certificate withdrawn; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The catch all clause that may make the colorblind condition an issue is the last requirement in the FAR &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iv) Not know or have reason to know of any medical condition that would make that person unable to operate a light-sport aircraft in a safe manner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are lots of light signals used in aviation that a red/green color blind person would have issues with. According to &lt;a href=&quot;http://www.flyingmag.com/safety/training/sport-pilot-meeting-lsa-stall-performance-limitations&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; color blind LSA pilots are restricted from flying into where color light signals may be used (these signals include but are not limited to tower light signals and ground based warning lights like those in the DC area). If your state issues you a color blind restriction on your drivers license it holds here as well, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Of course, any limitations placed on the driver's license would also apply to flying, and a person must always be physically able to perform the flight safely.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Furthermore it seems that according to &lt;a href=&quot;https://www.leftseat.com/baggish.htm&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt; you can have the restrictions lifted if you can pass a color blind test (I assume this applies to both the LSA restrictions as well as the regular PPL restrictions)  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-10T15:45:02.973" LastActivityDate="2015-11-10T15:45:02.973" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22830" PostTypeId="2" ParentId="16877" CreationDate="2015-11-10T16:27:32.247" Score="0" Body="&lt;p&gt;Normally you will never land at the wrong airport if it is towered because you make an announcement. So, for example, the pilot might say something like &quot;Norwood tower Fedex123 ten miles out on two six zero with information Juliette&quot;. Then the tower might say something like &quot;Fedex 123 please ident&quot;, then you ident. Then the tower might say &quot;I have you 25 miles out on three one zero&quot;. Then you know something is wrong. If the tower does not answer at all that is another sign something is wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once I started to land on the wrong airport. I was flying into Nashua Boire field (KASH) from the north late at night. At that time the tower was closed at Nashua, so I was just announcing on CTAF which goes unanswered and that is normal. I see the runway, line up and am coming in, when WHOA! a big Embraer slides in right below me. We had plenty of separation, but nevertheless I am like, &quot;What the hell is an Embraer doing here?&quot; The answer, of course, is that I was not landing at KASH, but at Manchester, a much larger airport directly north of Nashua. In the darkness one runway looks like another.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-11-10T16:27:32.247" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22832" PostTypeId="2" ParentId="15537" CreationDate="2015-11-10T20:30:20.720" Score="-3" Body="&lt;p&gt;It would probably be safer to replace one at a time in case the propellers were defective. Better safe on one good prop than sorry on two bad ones.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-10T20:30:20.720" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22833" PostTypeId="2" ParentId="21464" CreationDate="2015-11-10T20:49:59.500" Score="2" Body="&lt;p&gt;Basically it is that the more weight the moving object has (the turbine in this case) the more time it takes to slow down because of the energy stored in a moving object. It is the same in all object which have a large mass. In an automobile, there is the flywheel which stores some of the energy the engine produces so that a little hiccup in the pistons would not interrupt the spinning. With the jet engine, the large mass of the turbine also keeps the increase or decrease of speed at a constant rate so that the engine would not produce &quot;jerks&quot; of power when the throttle is changed. &lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-11-12T12:52:43.400" LastActivityDate="2015-11-12T12:52:43.400" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22834" PostTypeId="2" ParentId="21464" CreationDate="2015-11-10T21:43:40.070" Score="7" Body="&lt;p&gt;The simple answer is &lt;a href=&quot;http://hyperphysics.phy-astr.gsu.edu/hbase/mi.html&quot; rel=&quot;noreferrer&quot;&gt;rotational inertia&lt;/a&gt;, once you get a heavy mass spinning fast that heavy mass will have a tendency to continue spinning fast unless something else is acted upon the object. Piston engines have a great deal of friction between the piston walls and pistons (how they hold the explosion in) this helps them slow down faster than a jet in which the turbine is made to easily handle this thus the joints are very well made and very free moving. While cutting fuel will keep the engine from continuing to generate thrust the turbine will continue to spin until a force causes it to stop (drag and friction really). &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-11T14:49:05.730" LastActivityDate="2015-11-11T14:49:05.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22835" PostTypeId="1" CreationDate="2015-11-10T22:54:59.107" Score="0" ViewCount="51" Body="&lt;p&gt;So I of course know that the wing can stall at any angle of attack, but what then is the stall speed? Is that the speed at which the wing will always stall and it may stall at a higher speed?&lt;/p&gt;&#xA;" OwnerUserId="9619" LastActivityDate="2015-11-10T22:54:59.107" Title="If a stall is at the same angle of attack what is the stall speed?" Tags="&lt;stall&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-11-10T23:27:16.397" ContentLicense="CC BY-SA 3.0" />
  <row Id="22836" PostTypeId="2" ParentId="1757" CreationDate="2015-11-11T00:04:42.987" Score="4" Body="&lt;p&gt;That depends where in the world you are. In the UK, airport employees have had to go through the same type of security checks as passengers every time they enter secure areas of the airport since the early 1990s. The rest of the European Union adopted similar measures in 2004 (source: &lt;a href=&quot;http://www.bbc.co.uk/news/magazine-34731146&quot; rel=&quot;nofollow noreferrer&quot;&gt;BBC&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the report linked from &lt;a href=&quot;https://aviation.stackexchange.com/a/1761/946&quot;&gt;SSumner's answer&lt;/a&gt; the US decided seven years ago that it would be &quot;feasible&quot; to make employees go through security checks, too, but they still haven't done so.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-11T00:04:42.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22837" PostTypeId="1" CreationDate="2015-11-11T01:36:18.703" Score="7" ViewCount="29104" Body="&lt;p&gt;I have my private multi instrument and almost done with my commercial multi. A collegiate school's football team has requested that I fly the coaches (2-4) to their away games and other travel events throughout the year. Once I receive my certificate, am I legally permitted to fly them for hire without needing an operator's certificate? Maybe through a contract agreement?&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="69" LastEditDate="2015-11-14T08:05:08.203" LastActivityDate="2015-11-14T08:09:20.760" Title="Can a commercial pilot fly passengers for hire without an air carrier certificate?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;commercial-operations&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2015-11-14T08:13:17.943" ContentLicense="CC BY-SA 3.0" />
  <row Id="22839" PostTypeId="2" ParentId="22756" CreationDate="2015-11-11T03:10:37.297" Score="4" Body="&lt;p&gt;The rules on this are well-established and clear. They are laid out in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1185&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR §91.185(c)(2)&lt;/a&gt;. In particular, you should fly at an altitude which is (emphasis mine):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;At the highest of the following altitudes or flight levels &lt;strong&gt;for the route segment being flown&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;(i) The altitude or flight level assigned in the last ATC clearance received;&lt;/p&gt;&#xA;&lt;p&gt;(ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in §91.121(c)) for IFR operations; or&lt;/p&gt;&#xA;&lt;p&gt;(iii) The altitude or flight level ATC has advised may be expected in a further clearance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For each segment of your route, you evaluate the minimum, assigned, and expected altitudes, and fly the highest. In this case, you'd fly at 9,000 feet on the leg where the MEA is 9000, and then descend back to 8,000 when the MEA drops to that altitude or lower.&lt;/p&gt;&#xA;&lt;p&gt;If you lose your radios and squawk 7600 (or stop squawking altogether), ATC will expect you to fly those altitudes. They will provide separation between you and all other IFR traffic at 9,000 feet on the first leg, and 8,000 on the second leg. The only exception to this is if you encounter VFR conditions, in which case you should maintain VFR, land, and call ATC so they stop holding the airspace open for you.&lt;/p&gt;&#xA;&lt;p&gt;In this situation, you should not worry about inconveniencing ATC or other traffic. We have these rules specifically set up so that nobody trades paint if a radio fails. ATC will manage IFR traffic separation for you. &amp;quot;Better in terms of traffic separation&amp;quot; happens when everybody follows the same plan.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-11T03:10:37.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22840" PostTypeId="2" ParentId="21667" CreationDate="2015-11-11T06:11:21.163" Score="5" Body="&lt;p&gt;The Lilienthal reference says 4 degree gliding angle from the hill, in air velocities up to 33 feet/second- (presumably wind speed relative to the ground?) Neither reference gives the net change in altitude, and the wind speed, and ground speed at launch, for a specific flight of a particular distance. That's what's needed. From Lilienthal's gliding angle of 4 degrees one could imagine distance to descent ratio of 14.3:1, (slope=1/sin(4 degrees)) but we don't know if the 4 degree slope is in still air, a 33 fps head wind, a 33 fps tail wind, or something else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&quot;Wait!&quot;, you say, &quot;&lt;em&gt;tail&lt;/em&gt; wind?&quot; Sure. If distance from launching point is the figure off merit, you'd be a fool NOT to take a tail wind.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as computing glide ratio, the raw facts aren't here to compute it with certainty for either glider.  And slope lift (air driven upward by hitting terrain) ought to at least be checked if not factored in, as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its possible that a comprehensive table of air foils from the early days might have both the final glider airfoils for the Wrights and Lilienthal. And those air foils would have L/D ratios, but those are NOT the same as the gliding ratios of actual airplanes. The performance of the vehicles included not just the wing L/D but the parasitic drag of the whole structure and the wing loading. Which brings us back to the height of the descent and the distance covered.&lt;/p&gt;&#xA;" OwnerUserId="1897" LastEditorUserId="1897" LastEditDate="2016-01-22T09:27:02.403" LastActivityDate="2016-01-22T09:27:02.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22841" PostTypeId="1" AcceptedAnswerId="22843" CreationDate="2015-11-11T10:47:21.367" Score="11" ViewCount="2404" Body="&lt;p&gt;I was watching a timelapse video yesterday of the approaches on a busy airport (I don't remember which one), and I saw that about &lt;strong&gt;3 or 4&lt;/strong&gt; planes were lined up and descending at the same time (they were far from each other) and that got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is it possible (from a technical perspective) for more than one airplane to intercept the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2620/how-does-ils-instrument-landing-system-work&quot;&gt;ILS&lt;/a&gt; signals (glideslope and localizer) at the same time? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-11-12T09:38:44.553" Title="Is it possible for more than one airplane intercept the ILS at the same time?" Tags="&lt;instrument-flight-rules&gt;&lt;ils&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22842" PostTypeId="2" ParentId="22841" CreationDate="2015-11-11T11:03:25.680" Score="2" Body="&lt;p&gt;An ILS is a beam of radio energy pointed down the approach path, there's no limit to how many aircraft can be using it from a technology point of view. In practice you will only have a few descending on the ILS at the same time due to separation requirements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you could see the 4 airplanes on approach it means that conditions were visual, so the airplanes weren't necessarily using ILS for approach. It's probable they were all approaching visually. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-11T11:03:25.680" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22843" PostTypeId="2" ParentId="22841" CreationDate="2015-11-11T11:04:57.917" Score="13" Body="&lt;p&gt;Yes, since the ILS is just a set of radio signals emitted and received by aircraft, there can be more than one aircraft established on localizer and glidepath. The ILS does not lock or tune onto one single aircraft, it continuously broadcasts the localizer and glidepath signal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the localizer and glidepath antennas are located at the end of runway for the localizer and at the side of the runway for the glidepath, you will only need to worry about interference by aircraft on the ground, where they are close to the antennas and can deflect the signal due to proximity. This is why there are protection areas and aircraft need to hold at certain holding points, e.g. CAT II holding points when CAT II approaches are in use. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft in the air can also interfere and deflect the signal, however the emitted signals spread in a cone, so other aircraft still can receive the correct signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote &lt;a href=&quot;https://aviation.stackexchange.com/users/7629/keiths&quot;&gt;KeithS&lt;/a&gt; from one of the comments:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] basically, the localizer is projected from the far end of the runway, and the glideslope is projected from the side of the runway at or near the touchdown target. Thus, aircraft in line to touch down on the ideal target will have good line-of-sight to both transmitter pairs (unless there's an aircraft in the ILS Critical Area)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AVKOW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AVKOW.jpg&quot; alt=&quot;GS+LOC&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: www.aopa.org)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iIREk.jpg&quot; alt=&quot;http://cdn.londonreconnections.com/assets/planes.jpg&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://www.flickr.com/photos/nustyr/&quot; rel=&quot;nofollow noreferrer&quot;&gt;nustyR AirTeamImages&lt;/a&gt; (found via &lt;a href=&quot;http://www.londonreconnections.com/2012/london-and-its-airports-part-1-putting-the-math-into-aftermath/&quot; rel=&quot;nofollow noreferrer&quot;&gt;LondonReconnections&lt;/a&gt;))&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vuz90.png&quot; alt=&quot;FR24 Lined up Aircraft&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://aviation.stackexchange.com/q/7658/572&quot;&gt;When is an aircraft cleared to land?&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-12T09:38:44.553" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22844" PostTypeId="2" ParentId="22818" CreationDate="2015-11-11T11:50:20.570" Score="2" Body="&lt;p&gt;In general, the MRO services for corporate jets includes, but is not limited to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft major and minor inspections and overhaul&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft defect rectification and trouble shooting &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On-site defect rectification (away from base).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compliance of regulatory directives.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Replacement of avionics units.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft engine maintenance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The costs associated with these activities will vary depending on the model, location and aircraft condition. If you want actual costs, it would be best to contact the service provider directly.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-11T11:50:20.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22845" PostTypeId="1" AcceptedAnswerId="22847" CreationDate="2015-11-11T12:25:09.537" Score="40" ViewCount="7946" Body="&lt;p&gt;I have read that the wheel brakes on an aeroplane are by for the most efficient means of stopping it. I was wondering whether in low grip situations, such as in rain or snow, an ABS (Anti-lock Braking System) system is used to ensure the wheels do not lock. If not, why is this not necessary? &lt;/p&gt;&#xA;" OwnerUserId="12205" LastActivityDate="2019-04-10T12:22:05.867" Title="Do commercial aeroplanes use ABS to brake?" Tags="&lt;commercial-aviation&gt;&lt;landing&gt;&lt;landing-gear&gt;&lt;braking&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22846" PostTypeId="2" ParentId="22845" CreationDate="2015-11-11T12:34:19.600" Score="29" Body="&lt;p&gt;It is not called ABS but Anti-Skid, but the principle is similar. All large aircraft have it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose is however slightly different. In aircraft the nose wheel has relatively little weight on it and is usually not braked, so directional control, the main reason for ABS in cars, is possible¹ even without anti-skid. However due to the higher speeds and weights involved, aircraft have much higher risk of skidding and hydro-planning and when either happens, it can severely damage the tires, so the anti-skid is to prevent that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ To an extent. Since the nose wheel has little weight on it, it also has limited authority, so if the braking force becomes too asymmetric, the nose wheel can't compensate for it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-11-11T19:07:16.827" LastActivityDate="2015-11-11T19:07:16.827" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="22847" PostTypeId="2" ParentId="22845" CreationDate="2015-11-11T12:37:51.807" Score="42" Body="&lt;p&gt;Yes, they do. They are called Anti-Skid and they go from Mark I of 1948, with simply an on-off switch triggered by wheel lock, till Mark V (or at least that's the last I've seen), with quite complex control systems and sensors behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full details are a bit long to include them all here (there are &lt;a href=&quot;https://web.archive.org/web/20180306190508/http://www.actechbooks.com/products/act623/&quot; rel=&quot;nofollow noreferrer&quot;&gt;entire book sections about them&lt;/a&gt;). For a brief overview, see &lt;a href=&quot;http://cisb.org.br/wiefp2014/presentations/Session%206_Mario%20Maia.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this presentation&lt;/a&gt; from slide 12 till 18.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2019-04-10T11:48:22.857" LastActivityDate="2019-04-10T11:48:22.857" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="22848" PostTypeId="1" AcceptedAnswerId="22851" CreationDate="2015-11-11T13:41:47.170" Score="3" ViewCount="1429" Body="&lt;p&gt;I was chatting with an friend about the Embraer 135/145 and he mentioned that the engines have CVG. I assumed it might stand for &quot;continuously variable&quot; something, maybe &quot;gearing,&quot; but I'm not totally sure. What is CVG and how does it impact engine performance?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2015-11-11T14:02:46.470" Title="What is CVG in turbofan engines?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22849" PostTypeId="1" AcceptedAnswerId="22859" CreationDate="2015-11-11T13:52:39.533" Score="7" ViewCount="2037" Body="&lt;p&gt;I was having a discussion with a colleague about what aircraft qualify for logging complex time. We were discussing whether or not time flying transport-category turbojet aircraft qualified as complex according to the regulations. It's probably irrelevant at that point in a career, but my interpretation is that turbojet aircraft are not complex. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_11&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.1&lt;/a&gt; defines a complex aircraft as one having a retractable landing gear, flaps, and a controllable pitch propeller. It goes on to give some provisions for control computer or FADEC, but it still mentions propellor controls. In turbojet aircraft you just set the throttle, even if there are a lot of computer-controlled variables changing in the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it's not a jet, the &lt;a href=&quot;https://en.wikipedia.org/wiki/SOCATA_TBM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Daher-Socata TBM 900&lt;/a&gt; single-engine turboprop airplane has a single throttle quadrant and an automatically controlled propeller. It's still considered complex under the regulations even though there's no lever to adjust the prop and it's still complex. I give this example only because it has a single throttle lever and is still complex.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/0xxOK8I.jpg&quot; alt=&quot;TBM 900 Throttle Quadrant&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd love to get more interpretations on whether turbojet aircraft are technically complex according to the definitions of 14 CFR 61.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2017-04-20T16:28:50.007" LastActivityDate="2017-04-20T16:28:50.007" Title="Should time in turbojet aircraft be logged as complex?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="22850" PostTypeId="1" CreationDate="2015-11-11T13:54:29.797" Score="3" ViewCount="2228" Body="&lt;p&gt;When flying, I sometimes notice that the person behind the check-in desk also turns out to be the flight attendant on my flight. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this always the case, or did I just notice the exceptions? &lt;/li&gt;&#xA;&lt;li&gt;Why do airports use cabin crew for the (comparatively) simple job of checking bags, which could in theory be done by (presumably) cheaper lower-skilled employees? Or am I underestimating the difficulty of checking bags? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1478" LastActivityDate="2016-08-31T05:41:15.893" Title="Why do cabin crew also man check-in desks?" Tags="&lt;airport&gt;&lt;flight-attendant&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22851" PostTypeId="2" ParentId="22848" CreationDate="2015-11-11T14:02:46.470" Score="6" Body="&lt;p&gt;CVG stands for Compressor Variable Geometry. (e.g., &lt;a href=&quot;http://www.smartcockpit.com/docs/POWER_PLANT_E1.pdf&quot;&gt;this pdf, page 5&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a technique to change the pitch angle of the compressor vanes, much like a variable pitch propeller. Wikipedia does not have an article for the use in aircraft (probably because it's not used all that much), but does have an article on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Variable-geometry_turbocharger&quot;&gt;Variable-geometry turbocharger&lt;/a&gt; which is closely related (for non-car-enthusiasts: a turbocharger compresses inlet air with help of a turbine at the exhaust). Basically, this system lets you control the pressure ratio independent of the RPM. Advantages include&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;More efficient settings based on air pressure (altitude / temperature). You basically decouple the turbine stage from the compressor stage (but instead of a gearbox, you use the vane angle). This way, you can optimize your compressor stage to different conditions while keeping the turbine RPM at the most efficient value.&lt;/li&gt;&#xA;&lt;li&gt;More efficient cruise performance without compromising TO/GA capabilities. Aircraft engines are heavily overdimensioned to account for take-off power and contingencies, which means a bigger engine than strictly necessary and thus less efficiency in cruise. This can now be partially mitigated by varying the compressor vanes pitch for optimal efficiency during cruise and optimal power during TO/GA&lt;/li&gt;&#xA;&lt;li&gt;Higher engine RPM possible during approach. Normally, to keep your engines spooled up for eventualities, you need to increase their power, and as such need to increase drag with flaps and spoilers to keep the speed down. Now, you can spool up the engine to a high RPM with low compression ratio, and increase power relatively fast without having to overcome engine inertia by increasing the compression ratio by increasing the vane angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2015-11-11T14:02:46.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22852" PostTypeId="1" CreationDate="2015-11-11T14:05:47.577" Score="8" ViewCount="648" Body="&lt;p&gt;Will the lift coefficient (Cl) and drag coefficient (Cd) I obtain by using software simulations or subsonic wind-tunnel tests be the same as on an actual aircraft while cruising? Or will there be some error?&lt;/p&gt;&#xA;" OwnerUserId="12245" LastEditorUserId="4108" LastEditDate="2015-11-11T14:18:56.970" LastActivityDate="2020-07-26T05:29:21.100" Title="Do software simulations and wind-tunnel tests accurately predict Cd and Cl in real-world conditions?" Tags="&lt;aircraft-design&gt;&lt;lift&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22853" PostTypeId="2" ParentId="22841" CreationDate="2015-11-11T15:00:23.640" Score="8" Body="&lt;p&gt;If you look at the following picture, you'll see that a typical Localizer can giving reliable signals up-to 18NM from its position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zCIXN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zCIXN.jpg&quot; alt=&quot;Localizer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, a typical Glideslope can give reliable signals up-to 10NM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NTids.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NTids.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it is absolutely possible to have multiple-aircraft conducting the approach right behind each other as long as all aircraft receive positive guidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Needless to say, traffic separation has to be maintained according to the regulations.&lt;/p&gt;&#xA;" OwnerUserId="11136" LastActivityDate="2015-11-11T15:00:23.640" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22854" PostTypeId="1" CreationDate="2015-11-11T15:09:48.520" Score="14" ViewCount="9631" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/12886/4108&quot;&gt;This&lt;/a&gt; answer has a rather interesting (and quite lengthy) discussion, on a concept of using text-based rather than voice-based communication between ATC and the cockpit. As it turns out, &lt;a href=&quot;https://www.faa.gov/nextgen/datacomm&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA has some plans for that already&lt;/a&gt; as mentioned by @reirab. Being a simmer rather than a pilot, I've always found text-based ATC quite convenient (it provides a direct reference to your own instructions as well as instructions to others on your frequency), but the discussion in the linked answer showed some pilots opposed to such a system. My question is twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are the advantages and disadvantages of such a system?&lt;/li&gt;&#xA;&lt;li&gt;What is the current state of affairs of this concept? Are there specific methods of implementation across various instances - e.g., FAA, EASA, ICAO or other regulatory bodies - and do aircraft (systems) manufacturers anticipate such systems, or would perhaps a software update suffice on modern aircraft?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;: Perhaps it's better to concentrate mainly on IFR traffic, since their procedures are more formal (spacing, landing sequence etc. are decided by ATC) and things like voice call-outs (e.g., the nice voice that calls you a retard in an Airbus also calls for a go-around) are available at no extra cost.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2017-10-13T22:05:22.770" Title="What are the advantages, disadvantages and current state of affairs for text-based ATC?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;icao&gt;&lt;easa&gt;" AnswerCount="5" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22855" PostTypeId="2" ParentId="22854" CreationDate="2015-11-11T15:46:42.830" Score="11" Body="&lt;p&gt;I'm a newbie pilot, but I wanted to give the obvious example that crossed my mind when I read your question. In the UK GA world we have to, for example, call up to say we're on final approach. Finals can be a pretty busy time for the pilot, and at any kind of busy GA airport you're likely to have something along the lines of the following discussion:&lt;/p&gt;&#xA;&lt;p&gt;(Note in my example, my airport has an &amp;quot;Information Service&amp;quot; rather than full blown ATC, but nonetheless - the example stands)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Me: &amp;quot;G-AB Finals, Runway 16&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Tower: &amp;quot;G-AB, Runway Occupied&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Me: &amp;quot;Continuing, G-AB&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is me telling the controller that I'm aware I can't actually land, but I'll continue flying my approach path down towards some kind of decision height - somewhere around 300'. If I hear nothing again, I'll go around.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Tower: &amp;quot;G-AB, Land At Your Discretion&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Me: &amp;quot;Landing, G-AB&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I now continue my landing, except I'm not happy with my approach so I now declare a go around&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Me: &amp;quot;G-AB, Going Around&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Tower: &amp;quot;G-AB, Roger&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Remember that all of the above is going on while I'm setting flaps, keeping on the glideslope, watching the runway and maintaining my airspeed.&lt;/p&gt;&#xA;&lt;p&gt;Now also, imagine the alternative:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Tower: &amp;quot;G-AB, Land At Your Discretion&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Me: &amp;quot;Landing, G-AB&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So I now have clearance to land. I carry on, there's a bit of a crosswind and I'm working hard. I cross the airport boundary and I'm concentrating on the runway.. Unbeknown to me, a small dog/child/whatever has broken loose and is charging across the grass to the runway:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Tower: &amp;quot;G-AB, Go Around, I say again, Go Around&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;Me: &amp;quot;Going Around, G-AB&amp;quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In less than 2 seconds the danger is gone, and the tower know now that I've understood and acknowledged. Now in no world am I ever going to be looking down at a screen during that moment - even if a message came through and beeped/bonged or whatever - my concentration will be on landing. Now you might argue for a specific &amp;quot;Go Around&amp;quot; call/button or whatever - but how many of those different things will we end up with. I simply can't imagine a situation where I won't need my headset on and radio tuned.&lt;/p&gt;&#xA;&lt;p&gt;I'm not saying any of this stuff will never come in, but pressing a button to talk and listen is much more favourable to typing or reading something during critical phases of flight. At best, I can imagine it complementing some of the more mundane messages and perhaps Ground Controllers.&lt;/p&gt;&#xA;&lt;p&gt;An ATIS text system might be nice, and I imagine routing and similar will be useful - but I can't imagine it taking over voice completely. Sometimes you just can't beat talking - there's a reason people still e-mail the line &amp;quot;I'll call you&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;Beyond that - during those radio comms every aircraft in the vicinity now knows that G-AB is on Finals. This is incredibly important to GA traffic operating in VFR because pilots work hard to keep a mental picture of whose where - not to the degree the tower does, but if someone is following me but doesn't have visual (Very common - planes are surprisingly hard to spot), or loses visual, they know exactly where I am and what I'm doing.&lt;/p&gt;&#xA;&lt;p&gt;The aircraft that's just touched the threshold also knows that control are aware the runway is occupied and hasn't just cleared an aircraft to land.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-11T16:04:07.273" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22856" PostTypeId="2" ParentId="22854" CreationDate="2015-11-11T15:58:22.577" Score="7" Body="&lt;p&gt;The main concern with text ATC is the loss of &lt;a href=&quot;https://en.wikipedia.org/wiki/Situation_awareness&quot;&gt;situational awareness&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a controller issues an instruction, and the pilot responds, everyone else on that frequency also hears what's going on.  This is a major part of maintaining situational awareness and text based solutions, to my knowledge, have not yet come up with an alternative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Situational awareness is most important when things are busy which also co-incides with the times when reading or writing text is more difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Until these problems are solved, I can't see text replacing radio any time soon.  It may well augment it, for example by passing routing clearances which in general are not useful to others in maintaining awareness.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-11-11T15:58:22.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22857" PostTypeId="2" ParentId="22854" CreationDate="2015-11-11T16:50:44.677" Score="1" Body="&lt;p&gt;A very different answer to my first. While there's something of a catalogue of errors in this, the following audio recording is a clear display of why situational awareness is always a good thing to have:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/qUDFY5qlTSA?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the recording, Flight 1448 accidentally finds themselves on the Active Runway. Despite realising their mistake and speaking up, the controller (for whatever reason) simply asks them to hold while giving take off clearance to another aircraft on the same runway. Sensibly, after hearing what's going on, the second aircraft opts to hold instead of taking off.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-11-11T16:50:44.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22858" PostTypeId="2" ParentId="22837" CreationDate="2015-11-11T16:54:44.147" Score="6" Body="&lt;p&gt;If you are referring to the USA with the regulating body being the FAA, this link will give you your answer. All text below came from this site:&#xA;&lt;a href=&quot;http://www.cfidarren.com/cpinfo.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.cfidarren.com/cpinfo.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Here is the answer I think you are looking for:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If your customer approaches you, with his own airplane (either he rented it himself, or he owns it).  In this case you may fly for hire, because you are not offering your services as a package or &quot;holding out&quot; as a commercial operator -- air taxi or charter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Answer details:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Commercial Pilot Certificate&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A certificated Commercial Pilot is paid for services as a pilot, provided you meet the qualifications which apply to the type of operations you are doing.  Some of this flying is  controlled by Part 91, but most commercial flying is controlled by Part 119, 121, 125, 129, and 135.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Do I need a new medical certificate?&lt;/strong&gt;   To exercise your commercial pilot privileges, you must get a new medical (at least 2nd class) every year.  If your 2nd class medical expires (and becomes a 3rd class), you cannot exercise the privileges of a commercial pilot. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;What can I do with a commercial certificate?&lt;/strong&gt;    The following are things commercial pilots can do under part 91 - &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Local scenic flights within 25sm of departure airport.  &lt;/li&gt;&#xA;  &lt;li&gt;Ferry Flights  &lt;/li&gt;&#xA;  &lt;li&gt;Crop Dusting  &lt;/li&gt;&#xA;  &lt;li&gt;Banner Towing  &lt;/li&gt;&#xA;  &lt;li&gt;Aerial Photography  &lt;/li&gt;&#xA;  &lt;li&gt;Fire fighting &lt;/li&gt;&#xA;  &lt;li&gt;Go on to earn your flight instructor certificate&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Can I fly people around for money?&lt;/strong&gt;  You can certainly be paid for being a pilot with a Commercial Pilot Certificate.  You may work for an Air Carrier certificated under Parts 119, 135 or 121.  You may not be the Air Carrier conducting the business without getting an Air Carrier Certificate.  When you offer a package (airplane, price, pilot), you are no longer operating under Part 91 and would need an Air Carrier Certificate. An example would be &quot;Can you fly me to Atlanta?&quot;   If you provide the aircraft, you need to have an Air Taxi Commercial Operator certificate under Part 135.  There are different rules regarding maintenance, airworthiness requirements, crew member qualifications, and expanded VFR and IFR equipment lists that make Part 135 very different from Part 91.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;So the answer is &lt;strong&gt;NO&lt;/strong&gt;, you cannot fly people around for money.  A Commercial Pilot Certificate simply allows a pilot to be PIC engaged in a commercial operation (airline) that has an Air Carrier Certificate.  A pilot certificate does not entitle the holder to become a commercial air-taxi operator. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If your customer approaches you, with his own airplane (either he rented it himself, or he owns it).  In this case you may fly for hire, because you are not offering your services as a package or &quot;holding out&quot; as a commercial operator -- air taxi or charter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2015-11-12T20:39:07.970" LastActivityDate="2015-11-12T20:39:07.970" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22859" PostTypeId="2" ParentId="22849" CreationDate="2015-11-11T17:11:53.047" Score="3" Body="&lt;p&gt;Complex ratings apply only to aircraft with propellers, so any kind of jet aircraft is by definition not complex.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-11-11T17:11:53.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22860" PostTypeId="1" AcceptedAnswerId="22864" CreationDate="2015-11-11T17:15:03.877" Score="4" ViewCount="16596" Body="&lt;p&gt;I am currently studying for my commercial and I've been seeing both of these terms used interchangeably. Is there a difference?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="1696" LastEditDate="2015-11-11T17:55:38.137" LastActivityDate="2016-03-10T17:17:56.167" Title="What is the difference between an air carrier and a commercial operator?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22861" PostTypeId="2" ParentId="22854" CreationDate="2015-11-11T17:20:01.367" Score="9" Body="&lt;p&gt;The main advantages of text based ATC over voice based communication are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Earlier messages can be recalled&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Messages can be printed &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Messages can be read by automated systems, allow clearances to be loaded into the FMS&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;No inaudible messages due to radio static noise or simultaneous transmission&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Time saving and frequency congestion reduction when transmitting and confirming position reports, which otherwise can take up to &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/fo02txt.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;20-45 minutes&lt;/a&gt; on an HF frequency to wait one's turn and then transmit on a noisy frequency.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Some disadvantages are &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;time delay for urgent messages&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;not able to bring across emotions, e.g. when giving a critical instruction to avoid disaster&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;since the communication is private, other parties can't listen in and don't  know what is going on: loss of situational awareness.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This makes text based ATC unsuitable for the TMA and CTA. However in busy/large enough route sectors, the disadvantages are not an issue since there are rarely time critical messages and traffic situation awareness is of less importance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detailed information can be found in the &lt;a href=&quot;http://www.icao.int/APAC/Documents/edocs/GOLD_2Edition.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Global Operational Data Link&lt;/a&gt; document.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Text based ATC was developed as part of the Future Air Navigation System (FANS) and  is known as Controller-Pilot Data Link Communications  &lt;a href=&quot;https://en.wikipedia.org/wiki/Controller%E2%80%93pilot_data_link_communications&quot; rel=&quot;nofollow noreferrer&quot;&gt;(CPDLC)&lt;/a&gt;. It has been in limited operation since the end of the 1990s. Due to technical problems the uptake has been slow initially. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whilst the system is far from perfect today, its use is increasing. CPDLC is in use in En-route airspace over Europe and over the North Atlantic (NAT).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/a/11192/19&quot;&gt;this answer&lt;/a&gt; on the implementation phase on the NAT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From 2018, all IFR flights above FL285 in Europe have to be equipped with CPDLC. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="14897" LastEditDate="2017-10-13T22:05:22.770" LastActivityDate="2017-10-13T22:05:22.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22863" PostTypeId="2" ParentId="22845" CreationDate="2015-11-11T17:38:00.473" Score="14" Body="&lt;p&gt;The ABS systems in automobiles were based on the systems that had been in use in aircraft for decades.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ABS was first developed for aircraft use in 1929 by the French automobile and aircraft pioneer Gabriel Voisin, as &lt;em&gt;threshold braking&lt;/em&gt; on airplanes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Anti-lock_braking_system#History&quot;&gt;https://en.wikipedia.org/wiki/Anti-lock_braking_system#History&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12247" LastActivityDate="2015-11-11T17:38:00.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22864" PostTypeId="2" ParentId="22860" CreationDate="2015-11-11T17:43:55.847" Score="4" Body="&lt;p&gt;From &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=698c0142afb3ae01b23711087ec558e7&amp;amp;mc=true&amp;amp;node=pt14.1.1&amp;amp;rgn=div5&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 1&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Air carrier&lt;/strong&gt; means a person who undertakes directly by lease, or other arrangement, to engage in air transportation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sub&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Commercial operator&lt;/strong&gt; means a person who, for compensation or hire, engages in the carriage by aircraft in air commerce of persons or property, other than as an air carrier or foreign air carrier or under the authority of Part 375 of this title. Where it is doubtful that an operation is for “compensation or hire”, the test applied is whether the carriage by air is merely incidental to the person's other business or is, in itself, a major enterprise for profit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;To make this more clear &lt;a href=&quot;http://fsims.faa.gov/WDocs/8900.1/V02%20Air%20Op%20&amp;amp;%20Agency%20Cert/Chapter%2002/02_002_002.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Order 8900.1, Volume 2, Chapter 2, section 2&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;2-128    TYPES OF CERTIFICATES UNDER PART 119.&lt;/strong&gt; There are two, basic types of air operator certificates (AOC) issued to U.S. applicants who will conduct operations in common carriage. See Table 2-4, Certification for a summary of certificate requirements.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A.    An Air Carrier Certificate.&lt;/strong&gt; This certificate is issued to applicants that plan to conduct interstate, foreign, or overseas transportation, or to carry mail.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;B.    An Operating Certificate.&lt;/strong&gt; This certificate is issued to applicants that plan to conduct intrastate transportation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From your perspective it isn't a too important distinction.  As a commercial pilot all that matters to you is that both air carriers and commercial operators need to have operating certificates.  As a commercial pilot you can be hired by someone who has an operating certificate but you cannot provide the same services on your own unless you yourself have an operating certificate (e.g. a charter operator can hire you, but you cannot operate a charter service).&lt;/p&gt;&#xA;&lt;p&gt;As a commercial pilot you can be paid to act as PIC and can engage in the commercial operations that are excepted from operating certificates in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=698c0142afb3ae01b23711087ec558e7&amp;amp;mc=true&amp;amp;node=pt14.3.119&amp;amp;rgn=div5#se14.3.119_11&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 119.1(e)&lt;/a&gt;.  You cannot act as either an air carrier or a commercial operator without complying with 14 CFR 119, which requires that you have an operating certificate.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-11T17:50:39.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22865" PostTypeId="2" ParentId="22852" CreationDate="2015-11-11T19:47:47.300" Score="9" Body="&lt;p&gt;It depends.&lt;/p&gt;&#xA;&lt;p&gt;In computational fluid dynamics (CFD) there are limits for the calculation of turbulent flow. This means that large flow separation cannot be modeled precisely; especially its time-dependent characteristics are computationally much too complex to be modeled. Instead, statistical methods must be used.&lt;/p&gt;&#xA;&lt;p&gt;For attached and far-field characteristics the methods are refined enough to yield very accurate results, so much that what had historically been studied in wind tunnel tests or only on the finished aircraft can now be calculated with confidence up to hypersonic speeds. Errors still exist - after all, if the geometric model does not include the manufacturing irregularities of the real aircraft, the results will not be in total agreement, but close enough for engineering purposes.&lt;/p&gt;&#xA;&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/21646/why-cant-model-aircraft-be-used-to-discover-spin-and-stall-behavior-of-manned-a/21662?s=1%7C0.1757#21662&quot;&gt;wind tunnel testing&lt;/a&gt; you cannot expect the same results as long as the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7533/why-simple-paper-planes-fly-better-than-most-realistic-paper-plane-models/7536?s=6%7C0.1786#7536&quot;&gt;Reynolds number&lt;/a&gt; and Mach number are different from the real thing. This is adjusted with correction factors, and again the results become good enough for engineering purposes. &lt;a href=&quot;http://oai.dtic.mil/oai/oai?&amp;amp;verb=getRecord&amp;amp;metadataPrefix=html&amp;amp;identifier=ADA089050&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cryogenic wind tunnels&lt;/a&gt; even remove this restriction, but are very expensive to build and operate, because they run with pure nitrogen at very low temperature and several bars of pressure. Small errors remain, because all the details of the real aircraft cannot be modeled in a wind tunnel model and their ratio between dynamic pressure and stiffness cannot be adjusted for all flow conditions, so aeroelastic effects will remain different.&lt;/p&gt;&#xA;&lt;p&gt;Windtunnel tests are still valuable for predicting forces in post-stall conditions and for calibrating new CFD codes. Most of the operational envelope can then be covered with CFD. The combination of both is enough to predict the force coefficients with confidence, and only aeroelastic effects and details of the stall behavior might turn out slightly differently than anticipated from tests.&lt;/p&gt;&#xA;&lt;p&gt;As @TrebiaProject points out in the comments, CFD can help with the corrections. The influence of the sting the model is mounted on would be a primary example. CFD can help to understand its influence and correct for it. This makes CFD complementary, so both techniques will lead to better results if combined correctly.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-07-26T05:29:21.100" LastActivityDate="2020-07-26T05:29:21.100" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="22866" PostTypeId="2" ParentId="21667" CreationDate="2015-11-11T20:08:54.447" Score="7" Body="&lt;p&gt;Otto Lilienthal saw flying as something similar to bicycling: A sport and an opportunity to spend time out in Mother nature. Therefore, he designed all his airplanes such that they would fit through the door of a standard Reichsbahn freight wagon. He used a central truss (&lt;a href=&quot;http://www.collectors-edition.de/lilienthal_edition_seeamodelgrow_english.htm&quot; rel=&quot;noreferrer&quot;&gt;Gestellkreuz&lt;/a&gt;) to which willow stakes could be bolted such that they would fold backwards. He covered this structure with waxed cotton cloth and used wooden ribs to shape the airfoil of these wings. Consequently, the wingspan of his designs was limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next limitation was his way of controlling his aircraft only by weight shifting. Since his hands were already busy with holding on to the aircraft, he could not use them to move control surfaces. His drawings and his correspondence show that he considered control surfaces and even ailerons, but he did not incorporate them into his designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only his type 18 glider had a rectanguar inner wing which could be pulled close using a scissor link spar. However, with the bigger wing his weight shifting control showed its limits, as this did not lend itself to controlling gliders with bigger wingspans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another limit was his insistence that his aircraft would not need a runway or a launching device. Instead, he would grab handles in the Gestellkreuz, stand upright and use his legs as a landing gear. This limited not only the size, but also the wing loading of his designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wrigths, on the other hand, strived for the mechanically simplest and most lightweight designs and arrived at a biplane of constant chord and much higher aspect ratio. The &lt;a href=&quot;http://www.wright-brothers.org/Information_Desk/Just_the_Facts/Kites_&amp;amp;_Gliders/1902_Glider.htm&quot; rel=&quot;noreferrer&quot;&gt;1902 glider&lt;/a&gt; could already be flown in a prone position and the pilot could control it with control surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bd1RW.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bd1RW.png&quot; alt=&quot;Drag area of the human body in different poses&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag area of the human body in different poses, from Sieghart Hoerner's &lt;a href=&quot;https://books.google.de/books/about/Fluid_dynamic_drag.html?id=abU8AAAAIAAJ&amp;amp;redir_esc=y&quot; rel=&quot;noreferrer&quot;&gt;Fluid Dynamic Drag&lt;/a&gt;. The pilot of the Wright flyer caused only one fifth of the drag of the pilot in Lilienthal's designs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the wingspan of the Wright glider was much higher (9.6 m versus 6.7 m for Lilienthal's &lt;a href=&quot;https://en.wikipedia.org/wiki/Lilienthal_Normalsegelapparat&quot; rel=&quot;noreferrer&quot;&gt;Normalsegelapparat&lt;/a&gt;) and the much higher drag of the pilot's position in case of the Lilienthal design, the Wright glider certainly had a much better glide ratio.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-25T06:58:58.050" LastActivityDate="2015-12-25T06:58:58.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22867" PostTypeId="1" AcceptedAnswerId="22875" CreationDate="2015-11-12T03:46:01.847" Score="15" ViewCount="3482" Body="&lt;p&gt;Why can we use flaps in short field take off but not in high density altitude airports?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why can't they be used in high density altitude to shorten the take off distance as in short field take off? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why short field take off with flaps doesn't apply to high density altitude airports? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastActivityDate="2015-11-14T11:00:38.857" Title="Why not use flaps in take off from High Density Altitude airport?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;density-altitude&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22869" PostTypeId="1" CreationDate="2015-11-12T04:49:34.650" Score="1" ViewCount="1054" Body="&lt;p&gt;Why didn't Concorde use a scramjet engine for supersonic flight, but it is used in the &lt;a href=&quot;http://www.foxnews.com/travel/2015/10/15/airbus-patents-supersonic-aircraft-that-could-fly-from-london-to-new-york-in-1/&quot; rel=&quot;nofollow&quot;&gt;Airbus&lt;/a&gt; and &lt;a href=&quot;http://www.popularmechanics.com/flight/a18028/supersonic-skreemr-jet-could-fly-faster-than-mach-10/&quot; rel=&quot;nofollow&quot;&gt;Skreemr&lt;/a&gt; hypersonic flight concepts to achieve supersonic speeds?&lt;/p&gt;&#xA;" OwnerUserId="12127" LastEditorUserId="19" LastEditDate="2016-11-01T11:42:36.743" LastActivityDate="2017-09-27T18:00:53.223" Title="Why wasn't a scramjet used for the Concorde?" Tags="&lt;jet-engine&gt;&lt;propulsion&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22870" PostTypeId="2" ParentId="21766" CreationDate="2015-11-12T04:54:29.223" Score="0" Body="&lt;p&gt;high aspect ratios are provided for recon activities like lockheed martin U3 which had aspect ratio of 15 but this types of manned aircraft, pilot should be very high skilled&lt;/p&gt;&#xA;" OwnerUserId="12127" LastActivityDate="2015-11-12T04:54:29.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22871" PostTypeId="2" ParentId="22867" CreationDate="2015-11-12T05:51:06.957" Score="3" Body="&lt;p&gt;A cursory glance of this site reveals that &lt;strong&gt;the slight increase in lift is not worth the larger increase in drag&lt;/strong&gt; when deploying flaps at high-altitude/low air-density conditions.&#xA;&lt;a href=&quot;http://www.newconthenet.com/mountainflying.html&quot; rel=&quot;nofollow&quot;&gt;http://www.newconthenet.com/mountainflying.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4432" LastActivityDate="2015-11-12T05:51:06.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22872" PostTypeId="1" AcceptedAnswerId="22879" CreationDate="2015-11-12T08:19:16.803" Score="7" ViewCount="1347" Body="&lt;p&gt;How are collisions avoided when 2 aircraft are flying same altitude and same direction but have different speed characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example a B737 and an ATR are both flying at 25000 feet. 737 will cruise at 850 Km/h whereas the ATR will cruise at 550 Km/h and the 737 is approaching from behind. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is this type of situation handled by the pilots and ATC?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is specific to airliners as I have seen from websites like flightradar there are thousands of planes flying at any given moment and was wondering how this problem is handled.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2015-11-12T09:52:06.023" LastActivityDate="2016-10-22T09:34:26.870" Title="How does ATC maintain separation between aircraft flying at different speeds?" Tags="&lt;air-traffic-control&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22874" PostTypeId="2" ParentId="22869" CreationDate="2015-11-12T09:00:49.477" Score="8" Body="&lt;p&gt;The Skreemr at the present time is only an advertisement idea, so comparisons are not really meaningful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nevertheless, the difference with the Concorde is the expected range of speeds: at Mach ~2 a scramjet can hardly work (the air would be too slow at the combustion location).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All jet engines work on the same principles: compress (and slow down) the mass of incoming air in the compressor stage, heat it up in the combustion stage, let it expand (and accelerate) in the turbine/nozzle side.&#xA;If the compressor stage brings the air down below Mach 1, it is not a &lt;strong&gt;SC&lt;/strong&gt;ramjet anymore.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="5517" LastEditDate="2015-11-12T19:45:07.310" LastActivityDate="2015-11-12T19:45:07.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22875" PostTypeId="2" ParentId="22867" CreationDate="2015-11-12T09:01:17.840" Score="16" Body="&lt;p&gt;With more flaps, you will lift off at lower speed, but will have worse climb performance due to the increased drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On short field you are limited by the field length, so you need to lift off early and therefore need to use more flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in the mountains you are limited by the climb performance. Therefore you need to use less flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this is just general rule. You should look up performance for given density altitude and compare it with available runway length and required climb gradient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt; Extending flaps never improves &lt;em&gt;rate&lt;/em&gt; of climb. Up to some points it does improve &lt;em&gt;angle&lt;/em&gt; of climb though, because it reduces Vx and the engine can produce more thrust at lower speed. The setting for best angle of climb is higher than for normal take-off and is used on &lt;em&gt;obstructed&lt;/em&gt; field.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However as excess power reduces (with density altitude), Vx increases towards Vy (at absolute ceiling, Vx = Vy and rate of climb is 0) and the flap setting for best angle of climb decreases. So even for best angle of climb you shouldn't use as much flaps at high density altitude as at low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And most mountain airports are not obstructed. In most cases the valley ahead is large enough, but you want to get above the tricky winds &lt;em&gt;fast&lt;/em&gt; and you want high &lt;em&gt;rate&lt;/em&gt; of climb in case you encounter a downdraft. And that means no or little flaps.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-11-14T11:00:38.857" LastActivityDate="2015-11-14T11:00:38.857" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22876" PostTypeId="2" ParentId="22872" CreationDate="2015-11-12T09:06:13.180" Score="0" Body="&lt;p&gt;Such situations usually occur when you intercepted the localizer and is coming in for a landing, where many aircrafts line up in the air one behind the other coming in to land. These situations are maintained by slowing down the aircrafts which are at the back of the first aircraft and so on. Hence you hear &quot;(insert airline name) (insert number), you are number 2 (or number 3) for landing. Follow the company Boeing 777 on short final&quot;. &#xA;And once the aircraft at number one is landed, the second and third and so on lands one by one. Should there be a delay in the aircraft vacating the runway, the landing plane initiates a go around. &#xA;As far as planes at higher altitudes are concerned, you don't usually have such problems of one plane being exactly behind the other. The planes are slightly up or down or left or right and in this way it's easy for them to fly past one another. Hope this short answer helps. &lt;/p&gt;&#xA;" OwnerUserId="12256" LastActivityDate="2015-11-12T09:06:13.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22878" PostTypeId="2" ParentId="22624" CreationDate="2015-11-12T09:23:18.370" Score="0" Body="&lt;p&gt;I do tests on truck aerodynamics, and occasionally we put tufts on the vehicles. We then film these tufts to see how the flow behaves. We also use these RAM mounts, but sometimes one of them would come undone due to unproper mounting, dirt or flexing of the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We solved this issue by adding redundancy in the form of the Rollei 3x Suction Cup Kit:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/SKhRP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SKhRP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: Not affiliated to Rollei, this is just the first one we found.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastActivityDate="2015-11-12T09:23:18.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22879" PostTypeId="2" ParentId="22872" CreationDate="2015-11-12T09:31:09.973" Score="12" Body="&lt;p&gt;FL250 for a Boeing 737 in cruise at 850 kph/460 knots GS is an unlikely value. Aircraft in the same category of speed, such as the Boeing 737/747/767/777 usually fly at higher altitudes, e.g. FL300-FL400. Slower turboprop aircraft such as the ATR72 usually fly in the ranges of FL200-FL250. During cruise, airspeed will be matched by ATC for all aircraft where the trailing aircraft might catch up to the preceding aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC sees the ground speed on their radar screens and can thus compare and evaluate if they need to assign speeds to maintain separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N0jbp.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N0jbp.gif&quot; alt=&quot;ATC Datatag&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://aviation.stackexchange.com/q/12327/572&quot;&gt;What data does ATC see on their screens?&lt;/a&gt; - Speed: 395 knots GS)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R: DLH123, report mach number.&#xA;A: Mach .78, DLH123&#xA;R: BER456, report mach number.&#xA;A: Mach .79, BER456&#xA;R: BER456, reduce speed to mach .78&#xA;A: Reducing mach .78, BER456&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The same principle applies to aircraft in the terminal area, the lower you get, the more will aircraft have the same groundspeed when assigning the same indicated airspeed, as air density and wind approach the same values. ATC will sometimes assign a slower speed to trailing aircraft if they need to achieve the same groundspeed at different altitudes.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R: DLH123, descend to 3000ft, reduce speed to 210 knots&#xA;A: Descending to 3000ft, speed 210 knots, DLH123&#xA;R: BER456, descend to 4000ft, reduce speed to 200 knots&#xA;A: Descending to 4000ft, reducing speed to 200 knots, BER456&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;For aircraft that still have significantly different groundspeeds on the same airway, ATC can also vector aircraft around the preceding aircraft and put it back in front or they can issue a direct that will achieve the same effect, changing the sequence of the aircraft. A climb or descend can be coordinated with the pilots, e.g. the trailing aircraft can be asked if they are able to accept a climb to another flight level, maybe even temporarily.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-10-22T09:34:26.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22880" PostTypeId="1" AcceptedAnswerId="22881" CreationDate="2015-11-12T09:49:31.313" Score="40" ViewCount="18319" Body="&lt;p&gt;I have the diagnosis results for &lt;a href=&quot;https://en.wikipedia.org/wiki/Asperger_syndrome&quot;&gt;Asperger syndrome&lt;/a&gt; (scored 177 out of 76 required to get the diagnosis). Are there any regulations in Europe that can stop me from achieving my life goal: To fly commercial jets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My autism makes me very strongly interested in aviation, programming and audio design. But aviation is absolutely on top and has been since I was 6. The others have come as I age.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It might be a little off-track: So I'll add this little story just to add some &quot;meat&quot; to the question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I just recently went on a trip with a few of my co-workers that included a trip on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation#737-800&quot;&gt;B737-800&lt;/a&gt;. They thought it was special that I filmed the takeoff and landing, took pictures of it at the gate, and viewed out the window the entire two hours trip (my neck still hurts). They also had a funny reaction when I explained why the airflow to the cabin (packs) suddenly went silent as the engines start up. There is nothing more that I enjoy than flying, and I feel like I really belong up there (that poor kid in the seat in-front of me had a very different opinion).&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;I really wanted to see the cockpit during these flights. But asking is hard for me with Asperger. It kind of makes me feel like a 4-year-old.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;It might not count for much in the real world, but I have logged over 16,000 landings on my little home-simulator. Three of them are intended crashes just to test the simulation.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;All I ever wanted since I was a kid was flying commercial jets.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="693" LastEditorUserId="3386" LastEditDate="2017-06-12T20:58:35.090" LastActivityDate="2019-07-13T14:15:23.537" Title="Can you become a pilot with an Asperger syndrome diagnosis in Europe?" Tags="&lt;easa-regulations&gt;&lt;medical&gt;" AnswerCount="7" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22881" PostTypeId="2" ParentId="22880" CreationDate="2015-11-12T11:24:42.010" Score="60" Body="&lt;p&gt;In order to fly commercial you will need a first class medical certificate, and getting that with aspergers is going to be tough. The first consideration is the safety or people in the air and on the ground, so the criteria is conservative. Getting a first class medical would mean lots of extra hoops, even if it is possible. If you did get a medical you would then be competing against candidates who are neuro-typical, and would have to convince the airlines that you would be able to perform your job as well as non-aspergers candidates. That's not to say it's impossible, you would want to talk to a few aviation medical examiners about it to see what they say. If you can get a medical then you've got a chance, and if you are motivated enough and willing to work for it then I believe where there's a will there's a way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need to consider your own temperament when going for a pilots license of any kind, whether aspergers or neuro-typical. Flying is not just about the technical details, you need to be able to work with people, first of all your instructor! In commercial flying you also need to cooperate with other pilots and work with passengers, ground crew, and cabin staff. The extreme focus on detail and depth of knowledge on aviation you might develop with aspergers can be a huge asset in some ways, however aspergers could make it very challenging to work cooperatively in the cockpit, deal with troublesome passengers, and make quick and effective decisions. Think about some scenarios:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You are FO on a flight, the captain makes a decision you do not agree with&lt;/li&gt;&#xA;&lt;li&gt;A passenger is angry after the flight was delayed and is shouting abuse at you&lt;/li&gt;&#xA;&lt;li&gt;You are the captain of a flight that is low on fuel and had developed an emergency. You need to very quickly opt for continuing to the destination airport or diverting, and there are problems with either choice&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Do you think you would be able to successfully deal with these types of situations in the time frame you would have to work with? Not everyone is cut out for that sort of thing, whether aspergers or neuro-typical, these are scenarios all potential commercial pilots would need to be able to deal with. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think first you should figure out whether you like flying airplanes or not as a love of aviation and airplanes does not automatically mean you will love being at the controls. Why not go for your private license and find out? It's the first step in getting an ATPL anyway, and you could probably get a third class medical. You can then build on that if you want a career in aviation, or keep flying privately if you don't. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2015-11-12T14:24:43.140" LastActivityDate="2015-11-12T14:24:43.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22883" PostTypeId="2" ParentId="21622" CreationDate="2015-11-12T12:06:40.063" Score="0" Body="&lt;p&gt;In some newer planes i.e.B-787, A-380 etc., the CG is adjusted after loading the cargo.  The landing gear have solid state scales built in and in the extreme tailcone is a jackscrew with a very heavy weight attached, usually made of dense depleted uranium.  This can be moved laterally +/_ several feet to adjust the CG.&lt;/p&gt;&#xA;" OwnerUserId="12258" LastActivityDate="2015-11-12T12:06:40.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22884" PostTypeId="1" CreationDate="2015-11-12T12:15:40.687" Score="1" ViewCount="845" Body="&lt;p&gt;What is the reason behind that most (or many) military transport aircraft use turboprop engines?&lt;/p&gt;&#xA;" OwnerUserId="12259" LastEditorUserId="7532" LastEditDate="2015-11-17T04:11:29.943" LastActivityDate="2015-11-17T04:11:29.943" Title="Why most military transport aircrafts use turboprop engines?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-11-12T13:24:44.767" ContentLicense="CC BY-SA 3.0" />
  <row Id="22886" PostTypeId="1" CreationDate="2015-11-12T12:55:26.943" Score="1" ViewCount="3423" Body="&lt;p&gt;On Airbus, the window beside the Captain and the First Officer has the technical name of SIDE WINDOW.&#xA;What's the name on other aircraft, or they have the same specification?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="62" LastEditDate="2015-11-12T18:40:46.860" LastActivityDate="2015-11-12T20:54:21.720" Title="What's the technical name of the side window on Boeing and on Embraer?" Tags="&lt;aircraft-design&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22887" PostTypeId="2" ParentId="22884" CreationDate="2015-11-12T13:07:58.793" Score="2" Body="&lt;p&gt;It depends on the main purpose of the mission.&#xA;For example, for long haul flights, carring many pallets, they will use probably the turbo jets, because they have more endurance, and normally they will land on longer runways.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-11-12T13:07:58.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22888" PostTypeId="2" ParentId="22837" CreationDate="2015-11-12T14:34:53.427" Score="3" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If you are providing the airplane to transport the coaches:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are a commercial operator and require an operating certificate under part 119 to fly under part 135.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the coaches have an airplane (rental or owned) and are simply hiring you to fly it for them:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may provide your pilot services and act as PIC of their airplane and be paid while transporting the coaches as allowed under 61.133.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Your commercial pilot privileges are laid out in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_1133&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.133&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§61.133   Commercial pilot privileges and limitations.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Privileges—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) General. A person who holds a commercial pilot certificate may act as pilot in command of an aircraft—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Carrying persons or property for compensation or hire, provided the person is qualified in accordance with this part and with the applicable parts of this chapter that apply to the operation; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) For compensation or hire, provided the person is qualified in accordance with this part and with the applicable parts of this chapter that apply to the operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This says that a commercial pilot you may be paid to act as pilot of command.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To constrain this, you must also look at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5e81348c4c5f522e96302b35ac2e2c4f&amp;amp;mc=true&amp;amp;node=se14.3.119_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 119.1&lt;/a&gt;.  The important part to look at herei s 119.1(e):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Except for operations when common carriage is not involved conducted with airplanes having a passenger-seat configuration of 20 seats or more, excluding any required crewmember seat, or a payload capacity of 6,000 pounds or more, this part does not apply to—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Student instruction;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Nonstop Commercial Air Tours conducted after September 11, 2007, in an airplane or helicopter having a standard airworthiness certificate and passenger-seat configuration of 30 seats or fewer and a maximum payload capacity of 7,500 pounds or less that begin and end at the same airport, and are conducted within a 25-statute mile radius of that airport, in compliance with the Letter of Authorization issued under §91.147 of this chapter. For nonstop Commercial Air Tours conducted in accordance with part 136, subpart B of this chapter, National Parks Air Tour Management, the requirements of part 119 of this chapter apply unless excepted in §136.37(g)(2). For Nonstop Commercial Air Tours conducted in the vicinity of the Grand Canyon National Park, Arizona, the requirements of SFAR 50-2, part 93, subpart U, and part 119 of this chapter, as applicable, apply.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Ferry or training flights;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Aerial work operations, including—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Crop dusting, seeding, spraying, and bird chasing;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Banner towing;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iii) Aerial photography or survey;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) Fire fighting;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(v) Helicopter operations in construction or repair work (but it does apply to transportation to and from the site of operations); and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(vi) Powerline or pipeline patrol;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) Sightseeing flights conducted in hot air balloons;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) Nonstop flights conducted within a 25-statute-mile radius of the airport of takeoff carrying persons or objects for the purpose of conducting intentional parachute operations.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(7) Helicopter flights conducted within a 25 statute mile radius of the airport of takeoff if—  [snip]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(8) Operations conducted under part 133 of this chapter or 375 of this title;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(9) Emergency mail service conducted under 49 U.S.C. 41906; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(10) Operations conducted under the provisions of §91.321 of this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When you put those together you can always be paid to be PIC but if you provide the airplane and become an operator, then there is a very small list of things you can do without an operating certificate.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-12T14:34:53.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22889" PostTypeId="2" ParentId="22886" CreationDate="2015-11-12T14:41:08.677" Score="3" Body="&lt;p&gt;The windows to the side of the pilots on the Embraer airplanes are called &quot;Direct Vision&quot; (DV) windows.   They are named as such because they can be opened and removed both during normal ops on the ground and &lt;a href=&quot;https://aviation.stackexchange.com/a/13075/258&quot;&gt;emergency ops while airborne&lt;/a&gt; to provide forward vision when the main windscreens are obscured.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-11-12T14:41:08.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22891" PostTypeId="1" AcceptedAnswerId="22893" CreationDate="2015-11-12T17:55:36.630" Score="7" ViewCount="9238" Body="&lt;p&gt;How long is a winds and temperatures aloft forecast valid for and how often is it published?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, is there anywhere which says the times of publication and valid through times for all of the aviation weather charts? My google fu isn't helping.&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2019-07-30T09:21:59.637" Title="How long is a winds and temperatures aloft forecast valid for?" Tags="&lt;weather&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22892" PostTypeId="2" ParentId="22891" CreationDate="2015-11-12T18:06:58.020" Score="1" Body="&lt;p&gt;According to NOAA:&#xA;(&lt;a href=&quot;https://www.aviationweather.gov/products/nws/info&quot; rel=&quot;nofollow&quot;&gt;https://www.aviationweather.gov/products/nws/info&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sample winds aloft text message: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DATA BASED ON 010000Z VALID 010600Z   FOR USE 0500-0900Z. TEMPS NEG&#xA;  ABV 24000 FT  3000    6000   9000    12000   18000   24000  30000 &#xA;  34000  39000 MKC 2426 2726-09 2826-14 2930-21 2744-32 2751-41 275550&#xA;  276050 276547&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The portion that indicates valid times:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VALID 010600Z FOR USE 0500-0900Z.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The valid time of the forecast is the first day of the month at 0600 UTC. The forecast winds and temperature are to be used between 0500 and 0900 UTC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frequency of publication is described explicitly here:&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Winds_aloft&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Winds_aloft&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This forecast is now made four times a day based on 0000Z, 0600Z, 1200Z, and 1800Z &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2015-11-12T18:06:58.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22893" PostTypeId="2" ParentId="22891" CreationDate="2015-11-12T18:14:06.883" Score="11" Body="&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_00-45G_CHG_1-2.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory circular 00-45 &quot;Aviation Weather Services&quot;&lt;/a&gt; documents the winds and temperature aloft (FB) product on page 7-39.  Table 7-11 lists the standard forecast periods for these products.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MW3Cz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MW3Cz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this table you can see that the 6-hour forecasts are usable from the time they are issued until 3 hours after the valid time.  The 12 hour forecasts are usable from -3 to +6 hours of the valid time and 24 hour forecasts are usable from -6 to +6 hours of the valid time. The products are issued 4 times daily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While these are standard times, you should consult the specific information available in the product header that has this information.  For example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;DATA BASED ON 010000Z&#xA;VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000&#xA;FT 3000 6000 9000 12000 18000 24000 30000 34000 39000&#xA;MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This says the product is valid at 06Z and for use from 05Z to 09Z and the data is based upon the 00Z forecast model run.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-12T18:14:06.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22894" PostTypeId="2" ParentId="22880" CreationDate="2015-11-12T18:25:52.837" Score="13" Body="&lt;p&gt;It's going to depend on the specifics and severity of your condition. You can't generalize autism spectrum disorders. But Aspergers should not exclude you from flying. Flying commercial is another story. There's only one way to find out, so if you are really serious, you should contact the certification board and find out what the challenges are going to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What could be more problematic is if you also have sensory integration or sensory processing issues, which often accompany an autism diagnosis. As an example, I have a son with Aspergers who also has sensory integration issues. He has a very high threshold for pain, and there is almost nothing you can do that will make him dizzy. Those are attributes that could really be useful for a test pilot or acrobatic flyer. But he is also sensitive to loud noise, which is probably not a good attribute to have in aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will probably never be proven, but there are people who believe that Neil Armstrong had Aspergers, and he was a fine pilot, as we all know. Having read plenty about Armstrong in books by Chuck Yeager and other, and from my own personal experience with Aspergers, I tend to agree.&lt;/p&gt;&#xA;" OwnerUserId="9760" LastActivityDate="2015-11-12T18:25:52.837" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22895" PostTypeId="2" ParentId="22886" CreationDate="2015-11-12T20:54:21.720" Score="3" Body="&lt;p&gt;For Boeing, the captain's side window is the L2 window, with L1 in front of him, R1 in front of the coplilot, and R2 being the copilot's sliding window. The L3 and R3 window are aft of the sliding windows.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-11-12T20:54:21.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22896" PostTypeId="2" ParentId="22869" CreationDate="2015-11-12T22:00:08.130" Score="11" Body="&lt;p&gt;A supersonic &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717?s=15%7C0.0643#14717&quot;&gt;ram jet&lt;/a&gt; (scramjet) requires a fuel with a very high &lt;a href=&quot;https://en.wikipedia.org/wiki/Flame_speed&quot; rel=&quot;noreferrer&quot;&gt;flame speed&lt;/a&gt;, so the combustion doesn't take place after the fuel-air mixture has left the engine. Aviation fuel would be completely unsuitable, and only hydrogen gives acceptable results. The low density of gaseous hydrogen, the storage problems associated with &lt;a href=&quot;https://en.wikipedia.org/wiki/Cryogenics&quot; rel=&quot;noreferrer&quot;&gt;cryogenic&lt;/a&gt; hydrogen and the creation of a hydrogen infrastructure would had created tremendous problems for the Concorde development.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=2%7C0.0913#9222&quot;&gt;scramjet&lt;/a&gt; is like wing sweep: It is best avoided if possible, but necessary if you want to go really fast. For the scramjet the speed above which it makes sense is Mach 4 or 5, and Concorde was designed for Mach 2.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-09-27T18:00:53.223" LastActivityDate="2017-09-27T18:00:53.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22897" PostTypeId="1" CreationDate="2015-11-13T01:27:25.563" Score="0" ViewCount="282" Body="&lt;p&gt;For obvious reasons, that's the best way of tracking the whereabouts of my luggage. Once the plane lands, it would establish a 3G connection, and I would be able to access its GPS position. &lt;/p&gt;&#xA;" OwnerUserId="12267" LastActivityDate="2015-11-13T02:38:27.870" Title="Can I leave my smartphone turned on in the checked-in luggage?" Tags="&lt;cell-phone&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-11-13T10:47:09.630" ContentLicense="CC BY-SA 3.0" />
  <row Id="22898" PostTypeId="2" ParentId="22897" CreationDate="2015-11-13T02:38:27.870" Score="10" Body="&lt;p&gt;Your phone must be in airplane mode whether it is in the passenger cabin or cargo hold.  In this case the phone will never establish a 3G connection and won't meet your desired use case.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Leaving the phone with cell service on will likely also not solve your problem.  Cell phones tend to use a lot of battery trying to connect to a tower when there are none in range.  By the time you land your phone may have already shut down from losing power.  If the bag is lost it may be deep in the bag handling areas of the airport or some other corner with no cell service and certainly no GPS signal.  In all likelihood unless someone mistakenly takes your bag home and decides to charge your phone and turn it back on this plan of yours will not work.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-13T02:38:27.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22899" PostTypeId="2" ParentId="22880" CreationDate="2015-11-13T04:05:08.437" Score="3" Body="&lt;p&gt;One thing you should talk to your AME about is the potential for co-morbid conditions to affect your medical certification -- I have a similar diagnosis, but with co-morbid ADHD as well, and this means that best I can tell, I am ineligible for even a third class medical due to the ADHD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, definitely speak with an AME early on!&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-11-13T04:05:08.437" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22900" PostTypeId="2" ParentId="1436" CreationDate="2015-11-13T07:38:00.447" Score="-4" Body="&lt;p&gt;Easiest is internal. Look at overhead luggage compartments. If they raise up to close giving a sloping roof over the seats it is a Boeing. If the shutter comes from top and the roof over the seat is horizontal and immobile, it is an Airbus.&lt;/p&gt;&#xA;" OwnerUserId="12270" LastActivityDate="2015-11-13T07:38:00.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22901" PostTypeId="1" CreationDate="2015-11-13T10:35:46.773" Score="2" ViewCount="246" Body="&lt;p&gt;Any extra weight costs the airline in fuel. So, if none of the passengers carry any extra luggage (be it checked in or cabin luggage), will it lead to lesser fuel for the airline, thus lesser expenses, which would justify the lower  “zero-bag fares”.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, do the airlines have to meet some minimum weight criteria anyway to make any feasible fuel savings.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2015-11-13T17:37:48.057" Title="Are “zero-bag fares” really profitable for airlines?" Tags="&lt;fuel&gt;&lt;cost&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22902" PostTypeId="2" ParentId="22901" CreationDate="2015-11-13T10:52:11.243" Score="5" Body="&lt;p&gt;That's mostly a marketing ploy; people that don't have any bags are more likely to go with a airline that has a no-bag fare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However not having any checked-in luggage means less overhead in terms of baggage handling as it's a bag less to load and keep track of. It also means that if you got lost and didn't make it to the gate in time they don't have to offload any luggage but can simply pushback as soon as the gate closes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The freed-up space is then available for non-passenger cargo transport like mail. &lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-11-13T10:53:51.470" LastActivityDate="2015-11-13T10:53:51.470" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22903" PostTypeId="1" CreationDate="2015-11-13T11:35:56.540" Score="7" ViewCount="1408" Body="&lt;p&gt;According to the definitions, is there any difference between Jettison and Dump fuel?  Does one of them use a different procedure, or they are simply synonyms?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="28837" LastEditDate="2018-08-13T18:50:44.237" LastActivityDate="2018-08-13T18:50:44.237" Title="Jettison and Dump fuel - Do they have separate meanings?" Tags="&lt;terminology&gt;&lt;fuel-dumping&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="22904" PostTypeId="1" CreationDate="2015-11-13T12:14:16.840" Score="3" ViewCount="572" Body="&lt;p&gt;Is there any special training, relating to land under extreme weather, such as snow storms, contaminated runways or ice conditions?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="19" LastEditDate="2017-01-24T10:04:39.087" LastActivityDate="2017-01-24T10:19:40.947" Title="Does landing in extreme weather conditions require any different or special training?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;flight-training&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22905" PostTypeId="1" CreationDate="2015-11-13T12:43:43.517" Score="1" ViewCount="1795" Body="&lt;p&gt;Where can I find the NOAA's winds aloft data in a form that I can use in an application? I plan to develop a software able to calculate the flight path of a lighter than air aircraft or drone using windspeed data from the &lt;a href=&quot;https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs&quot; rel=&quot;nofollow&quot;&gt;NOAA Global Forecast System&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12272" LastEditorUserId="62" LastEditDate="2015-11-13T13:09:34.343" LastActivityDate="2015-11-13T22:06:53.427" Title="Is NOAA GFS winds aloft data available for applications?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22906" PostTypeId="1" AcceptedAnswerId="22914" CreationDate="2015-11-13T13:01:58.203" Score="2" ViewCount="682" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/15537/how-to-replace-two-propellers-on-the-same-aircraft-reaching-the-time-limit&quot;&gt;this&lt;/a&gt; question I've learned that after a propeller change the plane should go through a test flight. Why is this? &lt;/p&gt;&#xA;" OwnerUserId="11787" LastEditorUserId="15311" LastEditDate="2020-04-01T19:08:02.470" LastActivityDate="2020-04-01T19:08:02.470" Title="Why should a test flight be performed when the propellers are changed?" Tags="&lt;aircraft-maintenance&gt;&lt;propeller&gt;&lt;flight-testing&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="22907" PostTypeId="2" ParentId="22903" CreationDate="2015-11-13T13:05:45.933" Score="5" Body="&lt;p&gt;&lt;em&gt;Jettison&lt;/em&gt; &lt;a href=&quot;https://www.google.com/search?q=jettison&amp;amp;ie=utf-8&amp;amp;oe=utf-8&quot; rel=&quot;noreferrer&quot;&gt;means&lt;/a&gt; to 'throw something overboard', it isn't limited to fuel. To take a practical example, if I experienced engine failure in a light aircraft and had to make an emergency landing (especially a ditching), I might jettison any large or heavy items in the cabin to avoid them causing injuries during the landing. This appears in the ditching checklist for the C172, for example (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DITCHING &lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Radio -- TRANSMIT MAYDAY on 121.5 MHz, giving location and intentions and SQUAWK 7700. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Heavy Objects (in baggage area) -- SECURE OR &lt;strong&gt;JETTISON&lt;/strong&gt; (if possible).&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore, &lt;em&gt;dumping fuel&lt;/em&gt; is one specific type of jettisoning where only the fuel is jettisoned.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-11-13T13:05:45.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22908" PostTypeId="1" AcceptedAnswerId="22911" CreationDate="2015-11-13T13:59:42.403" Score="10" ViewCount="827" Body="&lt;p&gt;The Federal Aviation Administration released &lt;a href=&quot;https://www.faasafety.gov/files/notices/2009/Dec/SAIB_CE-10-11.pdf&quot;&gt;Special Airworthiness Information Bulletin CE-10-11&lt;/a&gt; on December 23, 2009 advising pilots of what procedures to use when resetting tripped circuit breakers. The background section refers to a crash where the airplane's weather radar system wiring caused a burning smell and the pilot pulled the breaker. When the breaker was reset for the next flight that flight subsequently crashed. I'm curious what flight this bulletin refers to because I'd like to read its associated NTSB report.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="917" LastEditDate="2018-01-14T14:46:56.943" LastActivityDate="2018-01-14T14:46:56.943" Title="What crash does FAA SAIB CE-10-11 refer to?" Tags="&lt;safety&gt;&lt;circuit-breaker&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22909" PostTypeId="2" ParentId="22906" CreationDate="2015-11-13T13:59:48.110" Score="1" Body="&lt;p&gt;It is so that the props are tested to see if they have any defects or not as well as to make adjustments based on their behaviour.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-13T13:59:48.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22910" PostTypeId="2" ParentId="22908" CreationDate="2015-11-13T14:30:06.933" Score="10" Body="&lt;p&gt;From the details it sounds like the accident was N501N, a Cessna 310R that crashed on 10 July 2007 (&lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0901.pdf&quot;&gt;NTSB Summary Report (PDF)&lt;/a&gt;).  This airplane had been previously written up for an anomaly with the weather radar and subsequently improperly released back into service.  The accident crew reported smoke in the cockpit and post-crash analysis revealed substantial electrical component damage, burned wire insulation, etc. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-13T14:30:06.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22911" PostTypeId="2" ParentId="22908" CreationDate="2015-11-13T14:30:19.803" Score="10" Body="&lt;p&gt;It was NTSB accident ID NYC07MA162. A Cessna 310R went down in Florida in 2007, the NTSB information is &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Pages/AAR0901.aspx&quot;&gt;here&lt;/a&gt; and the flight was &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2009/May/1/Safety-Pilot-Somethings-burning?_ga=1.105992899.1753081362.1440529514&quot;&gt;analyzed by AOPA&lt;/a&gt;. The NTSB &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0901.pdf&quot;&gt;report&lt;/a&gt; has lots of details, the aircraft was owned and operated by &lt;a href=&quot;https://en.wikipedia.org/wiki/NASCAR&quot;&gt;NASCAR&lt;/a&gt;, who &lt;a href=&quot;http://www.sportingnews.com/nascar-news/2055363-judge-tosses-out-nascar-lawsuit-against-cessna-over-deadly-2007-plane-crash&quot;&gt;unsuccessfully sued Cessna&lt;/a&gt; after the accident.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-11-13T14:30:19.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22912" PostTypeId="2" ParentId="22850" CreationDate="2015-11-13T15:12:37.097" Score="2" Body="&lt;p&gt;It probably depends on the airline and airport, because on the flights I have been on, the checking-in is managed by &quot;check-in staff&quot; who are not flight attendants. Larger airlines do the arrangement that I just describe while smaller ones might manage everything with the flight crew.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-13T15:12:37.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22913" PostTypeId="2" ParentId="22901" CreationDate="2015-11-13T15:37:31.413" Score="2" Body="&lt;p&gt;One thing this does allow the airline to do is sell the space as &lt;a href=&quot;http://science.howstuffworks.com/transport/flight/modern/air-freight1.htm&quot; rel=&quot;nofollow&quot;&gt;freight space&lt;/a&gt;. Since every plane out there has a maximum take off weight the airlines need to make sure they can fit People + Bags + Fuel on the plane before hand. If they allow each passenger to bring a 50Lb bag then they need to make sure that they can take off assuming everyone on board brought a bag even if no one brings a bag. If an airline can sell a no baggage ticket then they can turn around and guarantee that to freight hauling to make up the costs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some other cases it changes how people use the airline as a mode of transport. A lot of people fly for business and generally would stay the night in their intended destination for what may only be one day of meetings. If an airline offers cheap no bag fares an individual may chose to fly out in the morning and back home in the evening after their business is done in which case they may not need to bring a bag. This may help in having people fly both ways on the same airline (although most round trip tickets are booked on the same airline anyway). It also opens up idea of &quot;daily commuting&quot; on a plane.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-13T17:11:45.630" LastActivityDate="2015-11-13T17:11:45.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22914" PostTypeId="2" ParentId="22906" CreationDate="2015-11-13T16:13:03.057" Score="7" Body="&lt;p&gt;The purpose of the test flight is for the safety of passengers. For most maintenance, in a not-for-hire aircraft, a private pilot can perform the test flight and determine the aircraft is airworthy, but they must do it without passengers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.407&quot;&gt;Title 14 chapter 91.407&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-13T16:13:03.057" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="22915" PostTypeId="2" ParentId="22903" CreationDate="2015-11-13T17:15:59.520" Score="7" Body="&lt;p&gt;Jettison means to throw or drop (something) from an aircraft. Dumping fuel means the fuel (alone) is jettisoned. One can jettison any item (removable in flight) from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, a combat aircraft &lt;em&gt;jettisons&lt;/em&gt; its fuel tank, while a civil airliner &lt;em&gt;dumps&lt;/em&gt; the fuel, not the tank.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="15982" LastEditDate="2018-03-05T15:10:24.523" LastActivityDate="2018-03-05T15:10:24.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22916" PostTypeId="2" ParentId="22904" CreationDate="2015-11-13T17:34:46.370" Score="0" Body="&lt;p&gt;In commercial pilot training, they have to go through training for all sorts special situations training. Every pilot must go through training for such situation. So it probably is not &quot;special&quot; as requiring a whole new course or something like that although it might be &quot;special conditions&quot; inside the training programme. However, as a comment above said, it would be safer to divert to an alternate airport if possible.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-22T15:57:08.163" LastActivityDate="2015-12-22T15:57:08.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22917" PostTypeId="2" ParentId="22901" CreationDate="2015-11-13T17:37:48.057" Score="1" Body="&lt;p&gt;This is nothing to do with weight or costs. Using a 'zero bag' price with a surcharge allows them to advertise a flight for less, and many people will take that flight over one for twenty dollars more, without checking or realizing that the 'more expensive' flight gives them a free bag and the 'cheap' one charges forty dollars for a bag. It maximizes the chances that your flight shows up at the top when your flight is ordered by prices on the booking website.&lt;/p&gt;&#xA;" OwnerUserId="289" LastActivityDate="2015-11-13T17:37:48.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22918" PostTypeId="1" CreationDate="2015-11-13T18:11:20.897" Score="3" ViewCount="1986" Body="&lt;p&gt;The flights that I've been on in the Dreamliner (and also Virgin America), have dynamic overhead cabin lighting that provides nice mood lighting, helps alleviate jet-lag, and is otherwise very pleasing to look at. What is the technology behind this? The closest technology I've seen that can offer dynamic light coloring is phillips hue lightstrips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n9x5A.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n9x5A.jpg&quot; alt=&quot;Photo of Dreamliner colored interior cabin lighting&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12276" LastActivityDate="2015-11-14T00:39:56.423" Title="What is the lighting technology behind the Dreamliner's dynamic interior lighting?" Tags="&lt;aircraft-lighting&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22919" PostTypeId="2" ParentId="22918" CreationDate="2015-11-13T19:09:53.307" Score="2" Body="&lt;p&gt;According to Boeing they are using &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_5.html&quot; rel=&quot;nofollow&quot;&gt;High-intensity discharge (HID) and light emitting diode (LED) lighting&lt;/a&gt; almost across the board on the plane. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 787 has replaced virtually all cabin, flight deck and exterior lighting with HID and LED lighting technologies. Because these light types have no filament, the operational life of the lights is dramatically longer than that of an incandescent bulb.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The lights you show specifically are most likely &lt;a href=&quot;https://www.adafruit.com/products/159&quot; rel=&quot;nofollow&quot;&gt;tri-color LED's&lt;/a&gt; or some other similar array that would allow color selection and combination in a nice package (this is just my engineering assumption/how I would design it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once Boeing identified what light ranges relaxed people/helps jet lag the engineer would simply have to spec out LED's capable of delivering light in/at that spectrum. If they chose to use a tri-color package or single frequency LED's is up to them, the end result will be more or less the same optically speaking.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-13T19:19:03.663" LastActivityDate="2015-11-13T19:19:03.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22920" PostTypeId="2" ParentId="22905" CreationDate="2015-11-13T20:12:56.967" Score="1" Body="&lt;p&gt;See the following web page:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nws.noaa.gov/tg/general.php&quot; rel=&quot;nofollow&quot;&gt;http://www.nws.noaa.gov/tg/general.php&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This page describes getting started with the HTTP or FTP access to NOAA weather service APIs.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-11-13T20:12:56.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22922" PostTypeId="2" ParentId="22905" CreationDate="2015-11-13T22:06:53.427" Score="1" Body="&lt;p&gt;The GFS products can be accessed at &lt;a href=&quot;http://www.nco.ncep.noaa.gov/pmb/products/gfs/&quot; rel=&quot;nofollow&quot;&gt;http://www.nco.ncep.noaa.gov/pmb/products/gfs/&lt;/a&gt;.  You can use the filename scheme they list to pull down current forecast products from FTP.  These are the native output grids in grib2 format.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-13T22:06:53.427" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22923" PostTypeId="2" ParentId="22918" CreationDate="2015-11-14T00:39:56.423" Score="4" Body="&lt;p&gt;This 'mood' lighting is offered by Boeing in 787 and Airbus in A350XWB (as an option) and is achieved by using Light Emitting Diodes (LED). According to &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a350xwbfamily/onboard-well-being/&quot; rel=&quot;nofollow&quot;&gt;Airbus&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus is applying the latest technology in energy-efficient LED (light-emitting diode) mood-lighting on the A350 XWB. This enables the cabin ambience to be tailored to each airline’s own identity, as well as mimicking natural sunrise and sunset illumination that helps the body adapt to jetlag on long-range flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The main advantages of LEDs over conventional lights are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The LEDs are longer lasting (~50,000 hrs).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They are more energy efficient.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They generate less heat.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Phillips seems to be involved in the development of lighting systems for the(se) aircraft. According to &lt;a href=&quot;http://www.led-professional.com/resources-1/white-papers/led-lighting-masters-the-art-of-in-flight-calm-on-airbus-a380s-and-boeing-787s&quot; rel=&quot;nofollow&quot;&gt;led-professional.com&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Philips Lumileds provided the LEDs while Diehl Aerospace engineered the overall lighting system for the Boeing and Airbus cabin interiors. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The light intensity and colors are decided by the airliners and are pre-programmable (and can be changed remotely). According to &lt;a href=&quot;http://www.bloomberg.com/news/articles/2015-04-22/airlines-add-mood-lighting-to-chill-passengers-out&quot; rel=&quot;nofollow&quot;&gt;Bloomberg&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Finnair A350 cabin has two dozen light settings, aligned with stages of a long-haul flight. It will also feature warmer, amber colors on flights arriving in Asia and cooler “Nordic blue” hues when flying into Finland. ... &#xA;  Virgin Atlantic has five primary color periods on its 787 flights: rose-champagne for boarding, purple-pink for drinks, &quot;amber&quot; for dining, another for the pre-sleep period called “work-rest-play,” a silvery glow for overnight sleep, and a waking color. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.baesystems-ps.com/dynamic-led.php&quot; rel=&quot;nofollow&quot;&gt;Similar lighting systems&lt;/a&gt; are also offered by third parties for other aircraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-14T00:39:56.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22924" PostTypeId="2" ParentId="22906" CreationDate="2015-11-14T03:11:31.973" Score="4" Body="&lt;p&gt;Often when people talk about propellers, they think of them as a solid piece of material attached to the crankshaft of an engine. This is true for small planes, but absolutely untrue for larger aircraft.&lt;/p&gt;&lt;p&gt;On small aircraft, you might do a test flight to insure that the propeller functions properly in all flight modes. Mostly you'd be looking to insure that replacing the prop actually fixed the problem your were having. Defects in a fixed prop might make it vibrate due to not being properly balanced, which will show up on runup, or it might have an internal flaw that will only be apparent at particular flight modes, like ascending, descending or level flight and turns.&lt;/p&gt;&lt;p&gt;On larger aircraft, propellers are more sophisticated.&lt;/p&gt;&lt;p&gt;A reciprocating engine tends to develop maximum power in the 2200 to 2500 RPM range, so the engines are set to run in this range and the actual thrust is modified by changing the angle of attack of the propeller blades. This is usually accomplished by either an electric motor or a hydraulic piston. The motor or piston is in the hub and geared to the blades.&lt;/p&gt;&lt;p&gt;This makes the overall propeller system much more complex, and requires exercising it before certifying it flight ready even more important.&lt;/p&gt;&lt;p&gt;Adjustable propeller blades can be turned to a negative angle to allow engine braking on landing, and backing up on the ground. It can also be 'feathered' if there is an engine failure, so that the engine will not continue to turn over if it is shut down in flight.&lt;/p&gt;&lt;p&gt;&lt;b&gt;Additional notes:&lt;/b&gt;&lt;p&gt;There are other adjustable propeller systems that use air pressure or mechanical gearing.&lt;/p&gt;&lt;p&gt;Gas turbine engines have an even narrower maximum power range, and require even more complex propeller systems. They turn at around 10,000 RPM and use a gearbox to turn the props in the 2200 rpm range.&lt;/p&gt;&lt;p&gt;During my time in the Air Force, I changed propellers on C-124s, C-130s, C-133s, and a few other propeller driven aircraft. None of these changes required an actual flight verification, but did require a runup with a checklist for specific verification. Of course the pilots and flight engineer would be aware that the prop had been changed.&lt;/p&gt;&#xA;" OwnerUserId="11931" LastActivityDate="2015-11-14T03:11:31.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22925" PostTypeId="2" ParentId="1431" CreationDate="2015-11-14T03:59:17.850" Score="7" Body="&lt;p&gt;Here's a forced example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2006, I asked a CFIG what he would do if the rope release failed for both the glider and the emergency release on the tow plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He suggested we try the exercise of seeing what it would take to land on tow. (It turns out, it is REALLY easy to overrun the tow plane when on descent).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, technically, I have 3 glider touch-and-goes logged in my logbook. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/PjTdlx3p_jY?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="12285" LastActivityDate="2015-11-14T03:59:17.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22926" PostTypeId="2" ParentId="11237" CreationDate="2015-11-14T04:05:50.270" Score="1" Body="&lt;p&gt;Most gliders do have battery and/or solar-powered avionics and comms, so there can be electrical failures. In fact, one must take battery life into account for long flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gliders often fly much higher than other general aviation aircraft, so failure of the oxygen system with attendant hypoxia is a risk.&lt;/p&gt;&#xA;" OwnerUserId="12285" LastEditorUserId="12285" LastEditDate="2015-11-15T20:11:28.667" LastActivityDate="2015-11-15T20:11:28.667" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22928" PostTypeId="2" ParentId="2484" CreationDate="2015-11-14T10:57:28.057" Score="5" Body="&lt;p&gt;An aircraft must have a type certificate to legally fly in the US. This certificate signifies the aircraft's design passed all FAA requirements. Any alteration to the aircraft (including significant repairs) requires a supplemental type certificate, an FAA issued document. This being aviation, everything is an acronym. STCs amend the original TC. These STCs are filed with the FAA and copies are &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow noreferrer&quot;&gt;available&lt;/a&gt; to anyone.&lt;/p&gt;&#xA;&lt;p&gt;Modifications must be installed by a certificated (FAA speak for 'licensed') airframe and powerplant mechanic, an A&amp;amp;P - another acronym. &lt;em&gt;Powerplant&lt;/em&gt; refers to the aircraft's engine(s). Whenever a mechanic works on an airplane, she must make a logbook entry stating the what work was performed. The entry must include her mechanic's certificate number. Every US airplane must have an airframe logbook. If the airplane has engine(s), each engine has its own logbook. If an engine has a propeller, another logbook.&lt;/p&gt;&#xA;&lt;p&gt;Assuming you are still reading this... Each part installed as part of the STC installation must have evidence it was manufactured properly. This means it was made by an authorized manufacturer and that manufacturer attests the part complies with the necessary specifications. This is the 8130 form, also called a 'yellow tag.' Some are born yellow, whereas the non-yellow ones tend to turn yellow anyway.&lt;/p&gt;&#xA;&lt;p&gt;Airplanes are imperfect machines. From time to time, the imperfections are found. When the issue is moderate, the manufacturer issues a service bulletin. These are generally not mandatory. If the issue is serious, the FAA issues an airworthiness directive. Did you guess &lt;em&gt;SB&lt;/em&gt; and &lt;em&gt;AD&lt;/em&gt;? You would be right. Airworthiness directives are mandatory. Normally, they must be addressed within a certain number of flight hours. In severe cases, they must be complied with before the aircraft can be flown again, although often the aircraft is legal to fly one time to a maintenance facility. These directives can be one-time (replace this bolt with that longer one) or recurring (inspect this part for cracks every 100 flight hours).&lt;/p&gt;&#xA;&lt;p&gt;FAA regulations also require a complete annual inspection of the aircraft. This must be performed by a super-experienced A&amp;amp;P mechanic, one with 'inspection authorization'. Yes, this is an IA. The inspection must follow the aircraft's FAA approved maintenance manual. The results of the inspection are documented with entries in the various logbooks.&lt;/p&gt;&#xA;&lt;p&gt;The altimeter system must be tested every two years if the aircraft will be flying under instrument flight rules. This is IFR, and is flight without 'visual reference to the ground' as in flying in clouds, without seeing the sky, horizon or ground. From the front office (aviation-speak for the cockpit), it looks like someone covered all the windows with white paper, like a closed storefront. Anyway, This test must also be logged.&lt;/p&gt;&#xA;&lt;p&gt;All of these logs are not required to be in the plane, but they must be reasonably available for inspection if requested by an authorized person (usually an FAA representative known as a 'Fed'). Without these logbooks, the fed will issue a citation (ticket) and probably suspend the pilot's flying privileges.&lt;/p&gt;&#xA;&lt;p&gt;It is interesting to note the pilot is ultimately responsible. The owner, as far as the FAA is concerned, has little responsibility. Although the owner may be sued in criminal court, the pilot will receive the FAA's wrath.&lt;/p&gt;&#xA;&lt;p&gt;So, if you lose your airplane logbooks, what do you do? You can request the type certificate and STCs. You must then reconstruct as many records as possible. If you cannot prove compliance with airworthiness directives, you must re-perform the ADs.&lt;/p&gt;&#xA;&lt;p&gt;All of this will be very costly. It may be cheaper to sell the engine and avionics. And scrap the plane.&lt;/p&gt;&#xA;" OwnerUserId="12288" LastEditorUserId="12288" LastEditDate="2021-02-19T19:27:36.537" LastActivityDate="2021-02-19T19:27:36.537" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="22929" PostTypeId="1" AcceptedAnswerId="22934" CreationDate="2015-11-14T13:43:35.943" Score="4" ViewCount="1842" Body="&lt;p&gt;Let's say when flying, I encounter smoke and the smell of something burnt in the cockpit. Should I open the door or a window to clear the smoke?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My thoughts: the smoke may be toxic; opening the door brings in fresh air and avoid incapacitation. But, if something is burning, opening the door also brings in plenty of oxygen, and the fire will spread very rapidly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking about GA planes.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="62" LastEditDate="2015-11-14T20:30:41.957" LastActivityDate="2015-11-14T20:37:49.767" Title="Should I open a door or window when there is smoke in the cockpit?" Tags="&lt;emergency&gt;&lt;general-aviation&gt;&lt;cockpit&gt;&lt;fire&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22931" PostTypeId="2" ParentId="22155" CreationDate="2015-11-14T14:47:57.423" Score="3" Body="&lt;p&gt;In the older GA transponders where the code selection was made by turning knobs, the electrical contacts are made thru wafer discs in the back of each individual knob, with time and constant use is possible that the digit indicating disc slips and you'll end up squawking a different code than the displayed on the unit.&lt;/p&gt;&#xA;" OwnerUserId="12242" LastEditorUserId="6918" LastEditDate="2016-10-02T12:11:07.147" LastActivityDate="2016-10-02T12:11:07.147" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22932" PostTypeId="2" ParentId="22929" CreationDate="2015-11-14T15:54:22.863" Score="2" Body="&lt;p&gt;Burning smells in an aircraft always need to be taken seriously, not least because it could be a sign that you're breathing in carbon monoxide, which could effectively incapacitate you without you even realising. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an unpressurised aircraft you wouldn't exactly be bringing in more oxygen, so to speak, as the cabin altitude is already the same as outside. But yes you would be adding wind to a flame which could spread it instead of extinguishing it, but IMO this risk is worth taking compared to the alternative. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure if there's a formal recommended procedure for all aircraft, but it would be prudent to initially look around and see if there is a visible flame. If not, you must close all air conditioning vents and open the windows. If you see smoke you should land immediately in a field. If not, divert to the nearest airfield, ensuring the fresh wind is blowing in your face. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-11-14T15:54:22.863" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22933" PostTypeId="1" CreationDate="2015-11-14T18:13:06.863" Score="6" ViewCount="308" Body="&lt;p&gt;I live in a part of the country where VMC are starting to become increasingly uncommon, which has led me to wonder - &lt;strong&gt;which US airport historically has the most days in which VMC prevail per year&lt;/strong&gt;?  What sources of information can be used to investigate VMC trends at a given airport?&lt;/p&gt;&#xA;" OwnerUserId="8389" LastEditorUserId="62" LastEditDate="2015-11-14T20:31:27.350" LastActivityDate="2015-11-14T20:44:34.967" Title="Which US airport historically has the most days in which VMC prevail?" Tags="&lt;airport&gt;&lt;weather&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22934" PostTypeId="2" ParentId="22929" CreationDate="2015-11-14T20:30:30.347" Score="7" Body="&lt;p&gt;If possible, you should do whatever the operating handbook for your aircraft says but don't hesitate to do something different if you think it's necessary (more on that below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I checked a couple of POHs that I have to hand and they don't mention the doors specifically, but there is a slight difference in what they say about cabin ventilation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C172S checklist emphasizes avoiding drafts, including shutting air vents and ventilating only &lt;em&gt;after&lt;/em&gt; fighting the fire:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ELECTRICAL FIRE IN FLIGHT&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Master Switch -- OFF.&lt;/li&gt;&#xA;  &lt;li&gt;Vents, Cabin Air, Heat -- CLOSED.&lt;/li&gt;&#xA;  &lt;li&gt;Fire Extinguisher -- ACTIVATE.&lt;/li&gt;&#xA;  &lt;li&gt;Avionics Master Switch -- OFF.&lt;/li&gt;&#xA;  &lt;li&gt;All Other Switches (except ignition switch) -- OFF.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;WARNING&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;AFTER DISCHARGING FIRE EXTINGUISHER AND ASCERTAINING THAT FIRE&#xA;  HAS BEEN EXTINGUISHED, VENTILATE THE CABIN.&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;6&quot;&gt;&#xA;  &lt;li&gt;Vents/Cabin Air/Heat -- OPEN when it is ascertained that fire is completely extinguished.&lt;br&gt;&#xA;  [...]&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The PA28 checklist on the other hand says that the vents should be open:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FIRE IN FLIGHT&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Electrical fire (smoke in cabin):&lt;br&gt;&#xA;  Master switch....OFF&lt;br&gt;&#xA;  Vents....open&lt;br&gt;&#xA;  Cabin heat....OFF&lt;br&gt;&#xA;  Land as soon as practicable&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But practically speaking, fire in the cabin is a really extreme situation and it's hard to say that you should always follow the checklist (if you even physically can). For example, if the cabin fills with smoke and you can't see anything at all you might have to try to clear the smoke somehow just to keep control of the aircraft, even at the risk of feeding the fire. The Piper POH acknowledges that the pilot is the best person to decide what to do:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The procedure given is general and pilot judgement should be the&#xA;  determining factor for action in such an emergency&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For a real-life account of a cabin fire in a C172RG, see &lt;a href=&quot;http://www.aopa.org/AOPA-Live?watch=%7B91DFA1CA-D581-4B90-B9B5-51C8C44C7381%7D&quot;&gt;this AOPA Real Pilot Story&lt;/a&gt;. They had to open the door to be able to see and land, which reinforces the point about doing whatever you have to do in an extreme scenario.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-14T20:37:49.767" LastActivityDate="2015-11-14T20:37:49.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22935" PostTypeId="2" ParentId="22933" CreationDate="2015-11-14T20:37:13.023" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www1.ncdc.noaa.gov/pub/data/ccd-data/pctposrank.txt&quot; rel=&quot;nofollow&quot;&gt;According to NOAA&lt;/a&gt; here are the cities with &gt;80% annual sunshine which I've used as a proxy for VMC.  You'll find these cities are all in the desert southwest region of the US where the climate is arid. &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;SOURCE:  http://www.ncdc.noaa.gov/oa/climate/online/ccd/pctpos.txt&#xA;DATA THROUGH 2004&#xA;&#xA;CITY, STATE            ANNUAL % AVG POSSIBLE SUNSHINE        NO. OF YEARS OF DATA&#xA;YUMA, AZ               90%                                   42&#xA;REDDING, CA            88%                                   10&#xA;LAS VEGAS, NV          85%                                   47&#xA;PHOENIX, AZ            85%                                   101&#xA;TUCSON, AZ             85%                                   53&#xA;EL PASO, TX            84%                                   54&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;To investigate long-term trends you can &lt;a href=&quot;https://www.ncdc.noaa.gov/data-access/land-based-station-data&quot; rel=&quot;nofollow&quot;&gt;access historical data at the NCDC website&lt;/a&gt; and analyze the data for specific weather reporting stations.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-11-14T20:44:34.967" LastActivityDate="2015-11-14T20:44:34.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22936" PostTypeId="1" CreationDate="2015-11-15T05:45:42.847" Score="12" ViewCount="8651" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.5.7.4&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.407&lt;/a&gt; requires an &quot;Operational Check Flight&quot; of an aircraft before passengers may be carried in certain situations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.407   Operation after maintenance, preventive maintenance,&#xA;  rebuilding, or alteration.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may carry any person (other than crewmembers) in an&#xA;  aircraft &lt;strong&gt;that has been maintained, rebuilt, or altered in a manner&#xA;  that may have appreciably changed its flight characteristics or&#xA;  substantially affected its operation in flight&lt;/strong&gt; until an appropriately&#xA;  rated pilot with at least a private pilot certificate flies the&#xA;  aircraft, makes an operational check of the maintenance performed or&#xA;  alteration made, and logs the flight in the aircraft records.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does the FAA have any guidance that includes examples which better explain the bolded section from the regulation? It seems like that could be open to interpretation which could lead to different people having different ideas about when an operational check is required. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, is one required for routine maintenance like an engine change or prop change?  What about a flight control change or a flap change?  A new paint job (including the flight controls)? &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-11-16T05:27:56.717" LastActivityDate="2021-03-19T19:43:34.050" Title="Which aircraft maintenance repairs require a test flight?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;flight-testing&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22937" PostTypeId="1" AcceptedAnswerId="22939" CreationDate="2015-11-15T05:55:33.587" Score="2" ViewCount="838" Body="&lt;p&gt;When a new plane is being tested, could it at some phase carry passengers (maybe for free).. Or does it have to be certified, before it can carry a single passenger. Could some one throw some light on any FAA regulation in this regard&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="19" LastEditDate="2015-11-15T09:28:59.557" LastActivityDate="2015-11-15T11:35:24.247" Title="Can test flights carry passengers?" Tags="&lt;faa-regulations&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22938" PostTypeId="2" ParentId="22937" CreationDate="2015-11-15T07:31:15.413" Score="1" Body="&lt;p&gt;I can't imagine the FAA regulations being much different than the Australian CASA regulations on this one. So you're answer would be No. Only the required flight crew to pilot the aircraft, and a LAME (Licensed Aircraft Maintenance Engineer) if required.&lt;/p&gt;&#xA;" OwnerUserId="3223" LastActivityDate="2015-11-15T07:31:15.413" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22939" PostTypeId="2" ParentId="22937" CreationDate="2015-11-15T09:39:38.993" Score="4" Body="&lt;p&gt;Flight tests of new aircraft are covered under Part 21 Subpart B—Type Certificates &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b2071fa1ac187992060d27e71934e3ba&amp;amp;mc=true&amp;amp;node=pt14.1.21&amp;amp;rgn=div5#se14.1.21_135&quot; rel=&quot;nofollow&quot;&gt;§21.35 Flight tests&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no provision for the carrying of 'passengers' during any test flights, but then, there is no limit on the number of 'flight crew' either. FAA regulations does not &lt;em&gt;explicitly&lt;/em&gt; prohibit the carrying of any passengers as such; however, it places onus on the applicant for ensuring the safety of anyone abroad during test flights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) Each applicant must show for each flight test (except in a glider or a manned free balloon) that adequate provision is made for the flight test crew for emergency egress and the use of parachutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This places severe restriction on carrying of anyone during test flights. However, before certification, the manufacturer can carry passengers as long as it is not for commercial purposes. Actually, Airbus did this during the &lt;a href=&quot;http://www.airbus.com/company/aircraft-manufacture/how-is-an-aircraft-built/test-programme-and-certification/&quot; rel=&quot;nofollow&quot;&gt;test flights of A350 XWB&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Another important aspect of A380 and A350 XWB testing was the Early Long Flights (ELF) programmes, which went above and beyond certification requirements. For these evaluations, a cabin-equipped flight-test aircraft was operated on simulated commercial services with real “passengers” – comprised of Airbus employees – and actual airline flight crews to evaluate cabin systems in typical operating conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unless the flight testing is at an advanced stage or the manufacturer is extremely confident of the design, I don't see any non-essential flight crew being allowed in test flights, for obvious reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of test flights after maintenance or alteration, &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.407&quot; rel=&quot;nofollow&quot;&gt;CFR § 91.407&lt;/a&gt; - Operation after maintenance, preventive maintenance, rebuilding, or alteration says almost the same thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) No person may carry any person (other than crewmembers) in an aircraft that has been maintained, rebuilt, or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies the aircraft, makes an operational check of the maintenance performed or alteration made, and logs the flight in the aircraft records.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-15T11:35:24.247" LastActivityDate="2015-11-15T11:35:24.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22940" PostTypeId="2" ParentId="22880" CreationDate="2015-11-15T12:16:02.063" Score="8" Body="&lt;p&gt;&lt;em&gt;Since that other answers are perhaps not overwhelmingly optimistic, I thought I'd suggest another solution that might work out.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeing as to that you are also interested in programming, I would look into another aviation area: &lt;strong&gt;Unmanned Aerial Vehicles&lt;/strong&gt;, i.e. Drones. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No human passengers, so considerably fewer liability concerns. Proper ones are normally designed to be safe by design, i.e. terrain avoidance and flight envelope protection.&lt;/li&gt;&#xA;&lt;li&gt;Intensive and exciting development work being done. Can generally not be said about piloting.&lt;/li&gt;&#xA;&lt;li&gt;You can buy or build one yourself and then engineer and fly it. It's considerably more accessible.&lt;/li&gt;&#xA;&lt;li&gt;It is a considerably less regulated industry.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-11-15T12:16:02.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22941" PostTypeId="2" ParentId="22936" CreationDate="2015-11-15T13:13:14.963" Score="2" Body="&lt;p&gt;I found this on a website about STC Certificates and aircraft modifications:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;a. Applicant Flight testing precedes issuance of the TIA. The FAA will &amp;gt;review the applicants flight test reports and repeat some or all of the &amp;gt;tests as necessary. These repeated tests will be identified and performed &amp;gt;per the FAA issued TIA.&lt;/p&gt;&#xA;&lt;p&gt;b. FAA will perform flight tests for modifications which could affect the &amp;gt;aircraft's performance, flight characteristics, powerplant operation, &amp;gt;and/or overall handling qualities. Changes to systems, equipment, &amp;gt;instrumentation, and flight manuals may also require flight tests. Any &amp;gt;modification which may affect the noise signature and/or navigation of the &amp;gt;aircraft (including performance changes) will usually require fight &amp;gt;testing. The FAA project engineer can provide general information on the &amp;gt;types of tests which may be required.&lt;/p&gt;&#xA;&lt;p&gt;NOTE: Successful completion of the TIA tests by the FAA is one of the final &amp;gt;steps to STC issuance.&lt;/p&gt;&#xA;&lt;p&gt;c. Applicant testing.&lt;/p&gt;&#xA;&lt;p&gt;(1) Research and development flight tests are to ensure the design changes &amp;gt;are in compliance with the applicable 14 CFR's. The FAA will not &amp;gt;participate in or witness these tests. However, the FAA will discuss and &amp;gt;provide general guidance in order that such tests can be made meaningful &amp;gt;and safe. Alternatively, a Flight Test Pilot DER may be utilized to perform &amp;gt;such tests.&lt;/p&gt;&#xA;&lt;p&gt;(2) Flight test proposals are based on the knowledge of the modification &amp;gt;and development tests. The proposal should be based on the certification basis and include recommended tests, instrumentation to be used, necessary safety equipment, data acquisition, and reduction methods. Upon approval of the test proposal, descriptive and compliance data, and conformity established with the data, the FAA will issue a TIA. FAA flight test personnel should then be contacted to assure that potential hazards are recognized, the required test methods and criteria are understood, and for concurrence.&lt;/p&gt;&#xA;&lt;p&gt;NOTE: An applicant's flight test report should be submitted to the FAA for review upon successful completion of the inspection and test requirements equivalent to those required in the TIA.&lt;/p&gt;&#xA;&lt;p&gt;d. FAA testing may include repeating of tests, partially or in their entirety, to verify compliance to the certification requirements. FAA testing may be accomplished by an FAA pilot or an authorized DER flight test pilot.&lt;/p&gt;&#xA;&lt;p&gt;e. Installation Conformity inspection of the modified aircraft to be used for flight tests will be performed by the FAA or FAA designee prior to FAA testing. If discrepancies are found, they should be corrected and any test which could have been influenced may be repeated before further tests are performed by the FAA.&lt;/p&gt;&#xA;&lt;p&gt;f. Aircraft weight and the Center of Gravity (CG) location that is current and accurate is extremely important to assure the modified aircraft can be loaded to the critical weight and CG limits for flight testing. The aircraft to be used for official flight tests should be weighed and witnessed by an FAA representative before testing begins. The resulting weight and balance determination will be carefully checked by the FAA and, when found to be accurate, will be used for all subsequent flight test weight and CG calculations.&lt;/p&gt;&#xA;&lt;p&gt;g. Ballast necessary for flight testing should be securely restrained in such a manner as to withstand the inertial loads resulting from a survivable emergency landing. The preferred form for ballast is small, solid pieces of a high density metal (lead, cast iron, steel, or depleted uranium) fixed to the structure or in a suitable container that is fixed. Using passengers as ballast is not acceptable.&lt;/p&gt;&#xA;&lt;p&gt;h. Instrument calibration, when required, should be accomplished by an approved instrument repair inspector prior to the FAA flight test program with calibrated cards provided. Types of instruments to be calibrated may include: altimeters, tachometers, temperature gauges, airspeed indicators, etc. Calibrations should be performed within 3 months of the test. However, on critical items, this requirement may be 30 days.&lt;/p&gt;&#xA;&lt;p&gt;NOTE: Usually, the entire airspeed system is calibrated before flight testing.&lt;/p&gt;&#xA;&lt;p&gt;i. Rapid emergency egress provisions will be demonstrated to the FAA inspector and pilot for acceptability prior to FAA flight tests. Parachutes will be provided to the FAA, if required.&lt;/p&gt;&#xA;&lt;p&gt;j. Experimental Airworthiness Certificates, or special flight permits, are issued before operation for any aircraft which does not have a valid TC, or does not conform to its TC. Although the operations may eventually lead to a TC, they may be conducted only as a matter of research, or to show compliance to the appropriate 14 CFR.&lt;/p&gt;&#xA;&lt;p&gt;k. Flight manual supplements, or if an FAA approved Aircraft Flight Manual (AFM) does not exist, a supplemental flight manual, if required, will be provided to the pilot as a result of the modification, regardless of the method used on the original aircraft. A draft flight manual should be provided to the FAA prior to any flight tests. After FAA flight testing, the draft manual should be finalized and submitted for FAA review and approval. A guide for the format and preparing of a supplemental flight manual is provided in appendix 5 of AC 23-8A, AC 27-1, and AC 29-28.&lt;/p&gt;&#xA;&lt;p&gt;NOTE: The aircraft TCDS should be checked for identification of the FAA approved Aircraft Flight Manual, if appropriate. TCDS of many older aircraft state placards and markings are required (in lieu of a flight manual). Manufacturer owners' manuals may not be FAA approved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here is the link to the page: &lt;a href=&quot;http://www.astech-engineering.com/systems/avionics/aircraft/faastcprocess8.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.astech-engineering.com/systems/avionics/aircraft/faastcprocess8.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-15T15:57:15.330" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22942" PostTypeId="2" ParentId="22542" CreationDate="2015-11-15T13:25:46.147" Score="0" Body="&lt;p&gt;I'm Europe ACARS is typically used over VDL mode 2 or a satellite link like Inmarsat Classic Aero. An example of an application which is used over ACARS is CPDLC. &lt;/p&gt;&#xA;" OwnerUserId="12243" LastActivityDate="2015-11-15T13:25:46.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22943" PostTypeId="1" AcceptedAnswerId="22946" CreationDate="2015-11-15T16:14:36.460" Score="5" ViewCount="694" Body="&lt;p&gt;Some warning signal in modern airliners are voiced, like &lt;a href=&quot;https://www.youtube.com/watch?v=lHXk0KsRHmg&quot;&gt;TCAS warning&lt;/a&gt; and &lt;a href=&quot;https://www.youtube.com/watch?v=rpcfTX7qf8Y&quot;&gt;GPWS warning (PULL UP!)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And how many warning signal are voiced in the modern airliners?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover, where is the sound produced?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2015-11-15T16:53:05.217" Title="How many warning signals are voiced in modern airliners?" Tags="&lt;airliner&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22944" PostTypeId="1" AcceptedAnswerId="22945" CreationDate="2015-11-15T16:35:51.930" Score="19" ViewCount="8565" Body="&lt;p&gt;Look at this METAR:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;KLOU 151553Z 21005KT 10SM CLR 13/M01 A3044 RMK AO2 SLP309 T01281011 $&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does the dollar sign mean?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="3386" LastEditDate="2018-11-29T06:50:14.397" LastActivityDate="2018-11-29T06:50:14.397" Title="What does a dollar sign mean in a METAR?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22945" PostTypeId="2" ParentId="22944" CreationDate="2015-11-15T16:44:53.817" Score="32" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;A maintenance indicator sign, $, is included when an &lt;a href=&quot;https://en.wikipedia.org/wiki/Automated_airport_weather_station&quot; rel=&quot;noreferrer&quot;&gt;ASOS/AWSS&lt;/a&gt; (Automated Surface Observing System / Automated Weather Sensor System) detects that maintenance is needed on the system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/JO%207900.5C.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://www.faa.gov/documentLibrary/media/Order/JO%207900.5C.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or if you need an easy way to remember it, courtesy of the awesome Ralph J:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It means that they need to spend some money to fix whatever is broke on the automated reporting station!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="4095" LastEditDate="2016-05-03T00:41:28.447" LastActivityDate="2016-05-03T00:41:28.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22946" PostTypeId="2" ParentId="22943" CreationDate="2015-11-15T16:53:05.217" Score="10" Body="&lt;p&gt;Modern airliners have voice warnings in a number of systems like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ground Proximity Warning System&lt;/li&gt;&#xA;&lt;li&gt;Terrain Collision Avoidance System&lt;/li&gt;&#xA;&lt;li&gt;Windshear Alerts&lt;/li&gt;&#xA;&lt;li&gt;Radio Altitude callouts&lt;/li&gt;&#xA;&lt;li&gt;Trim&lt;/li&gt;&#xA;&lt;li&gt;Fire Detection&lt;/li&gt;&#xA;&lt;li&gt;Autopilot configuration&lt;/li&gt;&#xA;&lt;li&gt;Pressurization systems&lt;/li&gt;&#xA;&lt;li&gt;Landing gear system&lt;/li&gt;&#xA;&lt;li&gt;Stall/overspeed warning.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The amount of voice warnings vary from aircraft to aircraft. For example, &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/246525/&quot;&gt;airliners.net&lt;/a&gt; has the following list of voice warnings in Bombardier CRJ-200 (other than GPWS and TCAS):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;APU&quot; APU overspeed or overtemp&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Door&quot; open or unsafe passenger door indication&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Jetpipe Overheat&quot; overheat indication in jetpipe/pylon&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Smoke&quot; smoke detected in cargo area of lavatory&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Config Autopilot/Flaps/Spoilers/Trim/Brakes&quot; Aircraft not properly &#xA;  configured for takeoff&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Wing Overheat&quot; Overheat in fuselage wing anti-ice ducts&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Anti-ice Duct&quot; Bleed air leak in fuselage or wing anti-ice ducts&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Bleed Air Duct&quot; leak in different part of bleed air duct system&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Brakes&quot; brake overheat&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Config Brakes&quot; here again because it's for having the parking brake set &#xA;  while airborne&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Gear Disagree&quot; disagreement between gear indications and handle position&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Gear Bay Overheat&quot; overheat in main gear bay&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Nose Door&quot; Nose gear door open after gear fully extended and locked or &gt;250 &#xA;  knots&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Engine Oil&quot; oil pressure &amp;lt;25 psi&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Initially, most of the voice warnings were recorded voices. However, more and more modern systems (like in newer 737s) are using computer generated voices.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-15T16:53:05.217" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22947" PostTypeId="1" CreationDate="2015-11-15T16:53:34.777" Score="2" ViewCount="307" Body="&lt;p&gt;I am a student pilot and I am learning about radio signals/communication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am studying for a test and a practice questions states:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are flying circuits at a small airport and are flying at 1800ft ASL in the circuit (1000ft AGL) when you hear a radio call from a commercial jet at an airport 123 nautical miles to the south. Roughly how high does this jet need to be so that you can hear his radio call?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reference I can think of is that VHF signals can be heard by using a formula of: &#xA;Nautical miles = 1.23 * √ height above ground level. The answer would be 10000 ft (AGL)?, but I am not sure if that is the right formula to use or how to figure it out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please help.&lt;/p&gt;&#xA;" OwnerUserId="12297" LastEditorUserId="7532" LastEditDate="2015-11-15T19:17:24.170" LastActivityDate="2015-11-16T11:07:09.093" Title="How high does a jet have to be to hear its radio call?" Tags="&lt;radio-communications&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-11-18T05:54:01.430" ContentLicense="CC BY-SA 3.0" />
  <row Id="22948" PostTypeId="2" ParentId="22947" CreationDate="2015-11-15T19:26:12.887" Score="4" Body="&lt;p&gt;The formula you're using is correct, but don't forget your own altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$d = 1,23 × (\sqrt{h_1} + \sqrt{h_2})$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in your case:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$123 = 1.23 × (\sqrt x + \sqrt{1000})$$&#xA;$$100 = \sqrt x + 31.623$$&#xA;$$\sqrt x = 68.377$$&#xA;$$x = 4675\ \mathrm{ft}$$&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="524" LastEditDate="2015-11-16T11:07:09.093" LastActivityDate="2015-11-16T11:07:09.093" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22949" PostTypeId="1" AcceptedAnswerId="22952" CreationDate="2015-11-15T20:43:36.383" Score="19" ViewCount="3141" Body="&lt;p&gt;&lt;a href=&quot;http://www.usatoday.com/story/news/2015/11/11/experience-the-blue-angels-in-360-degree-video/75044212/&quot;&gt;This recently published 360-degree video&lt;/a&gt; shows four F/A-18 Hornets performing impressive maneuvers what appears to be only a few inches apart. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the risk of impact I find it hard to believe that a very slight contact would lead to immediate disaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this true? Assuming no damage is caused to the aircraft, how much impact can be handled (somewhat) safely? &lt;/p&gt;&#xA;" OwnerUserId="11665" LastEditorUserId="7532" LastEditDate="2015-11-15T23:26:38.593" LastActivityDate="2015-11-15T23:58:18.157" Title="How much impact can be taken when flying in formation?" Tags="&lt;safety&gt;&lt;military&gt;&lt;flying-in-formation&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22950" PostTypeId="2" ParentId="5114" CreationDate="2015-11-15T21:46:00.683" Score="-3" Body="&lt;p&gt;The term &quot;George&quot; as a reference to autopilots originated in the RAF in WWII.  It is a reference to the aircraft's &quot;owner&quot; King George.  Also, at the time, there was a popular radio show referenced in an earlier answer that may have reinforced the use of &quot;George&quot;. I have spoken to a number of British WWII pilots. Everyone assumed it was a reference to King George.  None of these pilots were aware of the name of the inventor of the earliest autopilot.  They were, however, aware of the name Sperry.&lt;/p&gt;&#xA;" OwnerUserId="12302" LastActivityDate="2015-11-15T21:46:00.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22952" PostTypeId="2" ParentId="22949" CreationDate="2015-11-15T23:26:08.363" Score="26" Body="&lt;p&gt;@Lnafziger is correct that absolutely ZERO contact between aircraft flying in formation is acceptable, with Aerial Refueling (AR) being the sole exception to this -- but in that case the AR equipment is designed to allow for what's going on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with contact IS the significant risk of damage to the aircraft involved, so the assumption in &quot;assuming no damage is caused, how much impact...&quot; is outside of typical experience.  IF you could assure no damage, then all sorts of things might be possible, but even pretty stoutly built fighter jets still aren't &quot;bumper cars&quot; and shouldn't be treated as such.  Even if a collision didn't cause an immediate structural failure, the risk of damage to the internal structure of the wing/tail/whatever would be enough that the aircraft would have to be taken apart &amp;amp; xray'd (or another non-destructive inspection method) to ensure that there wasn't damage that would later result in structural failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one exception to all of this that I can recall was a technique that the RAF used in WW II to defeat the V-1 &quot;buzz bomb&quot; cruise missiles.  While the Spitfires &lt;em&gt;could&lt;/em&gt; shoot them down, the small size of the missile meant that you had to get so close that you were probably flying through a cloud of debris right after you killed it (i.e. the warhead would detonate and the shrapnel might bring down the Spitfire as well).  They discovered that the gyroscopes in the V-1 guidance (i.e. the primitive autopilot) would tumble if they were inverted, so some pilots would fly formation with the V-1 then intentionally make contact with its wing with their own, flipping the buzz bomb onto its back.  At this point, the autopilot lost its bearings and the V-1 went down into (presumably!) empty countryside, crashing far from its London target.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than this, formation flight is carefully planned out so as to minimize all risk of contact between the aircraft.  Even in the (very cool!) video of the Blue Angels, you can see that there is always space between the wingtips -- more space for the more dynamic maneuvers, with the least space during a fairly brief and reasonably stable pass.  Remember, these pilots are extremely good &amp;amp; highly experienced in this sort of formation flying, and while there IS oscillation in pitch &amp;amp; roll, the formation is designed so that this can safely go on.  There just isn't much risk there of a force that would move one aircraft directly to the left or right of its position. Turbulence might produce a rolling or pitching motion that could LEAD TO a collision, but the pilots have enough control authority to correct these sorts of forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's why they're able to do what they do, safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly Navy!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-11-15T23:26:08.363" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22953" PostTypeId="2" ParentId="22949" CreationDate="2015-11-15T23:58:18.157" Score="22" Body="&lt;p&gt;During formation flying, &lt;em&gt;no&lt;/em&gt; contact is acceptable. At the speeds of demonstration, &lt;em&gt;any&lt;/em&gt; contact will be dangerous. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During formation flying, the pilots take every precaution to prevent accidental contact, including preventing accidental movement of control stick. According to &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/confessions-of-a-us-navy-blue-angel-1689568343&quot;&gt;Commander Shaun &quot;Linus&quot; Swartz&lt;/a&gt; of Blue Angels,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Blues attach a 40 lb spring to the stick in the jet. This spring applies 40lb of nose down stick pressure, so to fly straight and level each pilot is essentially doing a 40lb curl. The purpose of this is it takes out the slop in the stick (imagine driving down the street in your 1965 Ford F-100 and the wheel moves +/- a couple inches left or right without the truck actually moving, same thing happens in a jet, and you can't have that flying a few feet apart).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As an example of what will happen if there is contact during formation fling, consider the &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20021001-1&quot;&gt;crash of two Il-38s in 2002&lt;/a&gt;. During the ceremonial fly past, the wings of the two two aircraft brushed against each other, resulting in the death of all flight crew and another 3 on ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During formation flying, even flying into the aircraft wake can be dangerous- like the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie#Mid-air_collision&quot;&gt;XB-70 Valkyrie crash&lt;/a&gt;. Note that in both these examples, the aircrafts were flying in same direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, no contact is permitted in formation flying and pilots take every precaution against that.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-15T23:58:18.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22954" PostTypeId="2" ParentId="21317" CreationDate="2015-11-16T07:14:39.590" Score="3" Body="&lt;p&gt;Aeroalias provided a great answer!  Additionally, don't think of a magnetron as a component installed on an aircraft, think of it as a component installed within a black box (in this case, a transmitter, that's part of a system installed on an aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are multiple magnetrons listed within the link you provided above.  The first part number, 257-0261-020, is the original part number installed within a Collins black box.  The next two paragraphs are a cut and paste from the MPD Components, Inc.'s Products website (&lt;a href=&quot;http://www.mpdcomponents.com/products.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.mpdcomponents.com/products.htm&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MPD Components, Inc. is a diverse manufacturer capable of providing&#xA;  total solutions from ceramic insulators to complete RF assemblies. Our&#xA;  background and expertise is in applied electronics, microwave RF,&#xA;  Vacuum Electron Devices (VED's) and ceramic-to-metal sealing.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Magnetrons (VED's)--MPD offers positive and negative pulse magnetrons.&#xA;  Our magnetrons are for pulse applications with the majority being used&#xA;  for airborne weather radar and beacon magnetrons. Typical peak powers&#xA;  run from a minimum of 1.3 kW to 10 kW for Honeywell, Sperry, RCA,&#xA;  Bendix, King, AlliedSignal and Narco radars. Several magnetrons have&#xA;  FAA-PMA applications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You later asked if the transmitter is continuously powered and the technical answer is, &quot;yes...as long as the system is turned on.&quot;  That might seem like a cop-out answer, but it's true.  I &quot;think&quot; you meant to ask, &quot;Does the magnetron continuously transmit?&quot;  Without knowing the specific system the magnetron is installed, I don't think anyone can definitively answer how long it transmits, but it wouldn't be continuous or it would overheat.  For example, let's say this magnetron is installed in an aircraft radar system--the duty cycle (amount of transmission versus the amount of non-transmission) is going to vary based on what the radar system is designed to display (mode and range).  When the system is turned on and placed in a transmitting mode (not &quot;standby&quot;), the system will transmit a pulse, long enough to send the pulse.  Then the transmitter will shut down and the receiver circuits will open.  This prevents the receiver from taking in a high-powered signal (a received echo is very small).  For a pulse radar system, how many times the system transmits is called the &quot;PRF&quot; (Pulse Repetition Frequency or Pulse Recurring Frequency)--measured in pulses per second--and could be hundreds or thousands of times per second (depending again on the purpose of the particular radar system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last thing, somebody asked if transponders use magnetrons.  I think the answer is &quot;No&quot;, but there could be a transponder system that used them.  I believe most used a klystron.  Regardless of what generates the power of the transmission, what I wanted to say is that a transponder does not transmit the way I described above.  For example, an IFF transponder could be set to &quot;normal&quot; mode, operate correctly, and not transmit one time during flight.  How?  Because a transponder doesn't initiate the process like a radar system.  With transponders, an interrogator (airborne or ground system) initiates the process with a &quot;Who are you?&quot; type of signal.  &quot;If&quot; the airborne system receives a valid interrogation, the system will transmit a &quot;This is who I am!&quot; type of reply...otherwise, the system will stay in receive mode until it receives a valid interrogation.  If an air traffic control radar system or an airborne system believes they're properly interrogating, but there's no reply, they can use a communication system to verbally request the pilot to &quot;identify&quot;...and the pilot flip a switch, forcing the system to electronically transmit.  Again, what I described is &quot;normal&quot; IFF operation.  In an emergency (fire, hijacking, etc.), a pilot can select an &quot;emergency&quot; mode and the system will automatically start transmitting (squawking) the emergency code.&lt;/p&gt;&#xA;" OwnerUserId="12303" LastEditorUserId="1467" LastEditDate="2015-11-16T08:09:42.260" LastActivityDate="2015-11-16T08:09:42.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22955" PostTypeId="1" CreationDate="2015-11-16T10:48:51.857" Score="15" ViewCount="1779" Body="&lt;p&gt;As explained in this Q/A:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/22944/what-does-a-dollar-sign-mean-in-a-metar/22945?noredirect=1#comment53121_22945&quot;&gt;What does a dollar sign mean in a METAR?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The presence of a Dollar Sign ($) at the end of a METAR is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;included when an ASOS/AWSS detects that maintenance is needed on the&#xA;  system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does this therefore imply we should not trust this METAR? If so - why do they even continue to publish it? If not, why are pilots informed that the system requires maintenence?&lt;/p&gt;&#xA;" OwnerUserId="2160" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-11-16T12:18:01.170" Title="Does the &quot;Maintenance Indicator&quot; sign on a METAR imply we can't trust it?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22956" PostTypeId="2" ParentId="22955" CreationDate="2015-11-16T12:18:01.170" Score="8" Body="&lt;p&gt;Not necessarily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automated stations have a number of sensors for detecting,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind speed and direction&lt;/li&gt;&#xA;&lt;li&gt;Visibility&lt;/li&gt;&#xA;&lt;li&gt;Obscurations to vision&lt;/li&gt;&#xA;&lt;li&gt;Cloud coverage and ceiling&lt;/li&gt;&#xA;&lt;li&gt;Temperature and dew point&lt;/li&gt;&#xA;&lt;li&gt;Barometric pressure and altimeter setting&lt;/li&gt;&#xA;&lt;li&gt;Precipitation&lt;/li&gt;&#xA;&lt;li&gt;Freezing rain (Icing)&lt;/li&gt;&#xA;&lt;li&gt;Lightning (thunderstorms)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is likely that some of these are not functioning properly, while the others are working correctly. In such cases, the METAR reports contain sensor status indicators which give information about the sensor which has failed. For example, consider the following METAR:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;KMEM 230853Z AUTO 18014G18KT 10SM CLR 16/M02 A3008 RMK AO2 SLP117&#xA;       T01561022 TSNO $   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here, TSNO indicates that the automated station is equipped with a lightning detection system and that sensor is not operating. Following is a list of sensor status indicators:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;RVRNO- Runway Visual Range is missing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;PWINO- Present weather identifier sensor (is fitted and) is not operating&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;PNO- Tipping bucket rain gauge sensor is not operating.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;FZRANO- Freezing rain sensor is not operating&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;TSNO- Lightning detection system sensor is not operating&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;VISNO_LOC- Secondary visibility sensor is not operating.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CHINO_LOC- Secondary ceiling height indicator and that sensor is not operating.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-16T12:18:01.170" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22957" PostTypeId="1" AcceptedAnswerId="22992" CreationDate="2015-11-16T13:11:56.870" Score="9" ViewCount="829" Body="&lt;p&gt;Does anyone know if it's possible to put FAA flight school hours towards an EASA (UK/CAA) PPL? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard answers from &quot;NO&quot; to &quot;Of course&quot; and everything in between, but am struggling to find any documentation that gives a definitive answer one way or another. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I can see FAA hours can't be used for credit towards specific training but they can be credited towards the 45 hours total time needed for the license. If anyone has links to appropriate documentation I'd really appreciate it.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2015-11-18T14:00:44.117" Title="Can hours at an FAA flightschool be credited to an EASA PPL?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;ppl&gt;&lt;easa&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22958" PostTypeId="1" CreationDate="2015-11-16T14:07:47.100" Score="1" ViewCount="357" Body="&lt;p&gt;Why don't some airlines (for example Southwest in US) assign seats to passengers? How does it help them? Doesn't it delay the boarding (passengers going back and forth inside the plane to grab their favorite seats)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any studies to show that this is a better method? Or is there any technical reason why some airlines does this while others do not?&lt;/p&gt;&#xA;" OwnerUserId="11628" LastEditorUserId="11628" LastEditDate="2015-11-16T23:22:31.400" LastActivityDate="2015-11-16T23:22:31.400" Title="Why don't some airlines assign seats to passengers?" Tags="&lt;airlines&gt;" AnswerCount="1" CommentCount="12" ClosedDate="2015-11-16T18:31:09.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="22959" PostTypeId="2" ParentId="22958" CreationDate="2015-11-16T14:51:35.137" Score="1" Body="&lt;p&gt;It is mainly used by low-cost single-class cabin airline companies to make the reservation process simpler.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-16T14:51:35.137" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22961" PostTypeId="1" AcceptedAnswerId="22962" CreationDate="2015-11-16T19:24:16.107" Score="10" ViewCount="1060" Body="&lt;p&gt;What type of SUA is AR633A, the cyan racetrack-shaped SUA north of Knoxville, Tenneessee (&lt;a href=&quot;https://skyvector.com/?ll=36.230316621979334,-83.85754393934181&amp;amp;chart=301&amp;amp;zoom=5&quot; rel=&quot;nofollow noreferrer&quot;&gt;KTYS&lt;/a&gt;) depicted below on &lt;a href=&quot;http://sua.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;sua.faa.gov&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why doesn’t it correspond to anything on the VFR sectional?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s2r87.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s2r87.png&quot; alt=&quot;AR633A&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2015-11-17T10:44:48.290" LastActivityDate="2015-11-17T10:44:48.290" Title="What is this racetrack-shaped Special Use Airspace, and why isn’t it on the VFR sectional?" Tags="&lt;aeronautical-charts&gt;&lt;special-use-airspace&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22962" PostTypeId="2" ParentId="22961" CreationDate="2015-11-16T19:33:46.710" Score="8" Body="&lt;p&gt;&lt;a href=&quot;http://web.ornl.gov/info/reports/1992/3445603687295.pdf&quot; rel=&quot;noreferrer&quot;&gt;According to this report&lt;/a&gt; on air crashes AR-633 (I assume the same as AR-633A now)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The cities of Oak Ridge, Knoxville, and Rockwood lie beneath AR-633, a&#xA;volume of airspace used by the 134th Tennessee Air National Guard Air&#xA;Refueling Group for practicing air refueling (Sect. 2.2). Although&#xA;under military jurisdiction, this designated airspace is equivalent to&#xA;an FAA holding pattern. AR-633 has an airspace volume of approximately&#xA;97 statute miles x 41 statute miles x I statute mile in depth.&#xA;Refueling operations take place within this box of airspace. Because&#xA;the military has jurisdiction over this volume of airspace and&#xA;operations may be considered sensitive, it is impossible to determine&#xA;whether refueling operations by the 134th Air Refueling Group occur&#xA;directly over the Oak Ridge reservation. The Oak Ridge reservation&#xA;encompasses an area of approximately 58 sq mi; the refueling area used&#xA;by the military (AR-633) encompasses 4,000 total sq mi.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://sua.faa.gov/sua/ListHelp.html&quot; rel=&quot;noreferrer&quot;&gt;Text List Help for sua.faa.gov&lt;/a&gt; defines the AR Special Use Airspace type as&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TYPE: &lt;strong&gt;AR - Aerial Refueling Route&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;DEFINITION: An aerial refueling route is airspace used by military tankers that routinely refuel other military aircraft along published altitudes (in most cases above 10,000 feet AGL).&lt;/p&gt;&#xA;&lt;p&gt;PURPOSE: Aerial Refueling Routes are identified to inform non-participating pilots of the potential danger from activities being conducted. This airspace is not prohibited as long as other aircraft provide vertical or lateral separation from the refueling aircraft. Contact the assigned FSS for AR details.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-16T23:43:10.340" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22963" PostTypeId="2" ParentId="13421" CreationDate="2015-11-16T20:46:51.007" Score="1" Body="&lt;p&gt;A working anti collision light is not required for the 1967 Cherokee because the key statement in 95.205b11 is for aircraft certificated in accordance with FAR part 23.  A Piper Cherokee  was certified under CAR (civil aviation regulations) part 3, not FAR part 23 (See TCDS 2A13). Therefore this sub paragraph does not apply to that aircraft. If, and only if, this aircraft is operated at night (as specified in 91.209 the light would be required...but not for Day VFR.&lt;/p&gt;&#xA;" OwnerUserId="12315" LastEditorUserId="12315" LastEditDate="2015-11-16T20:53:51.993" LastActivityDate="2015-11-16T20:53:51.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22964" PostTypeId="2" ParentId="758" CreationDate="2015-11-16T21:28:43.010" Score="3" Body="&lt;p&gt;All of the people here are correct.  Your license has no expiration date, but your medical does, depending on your age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I personally went 15 years without flying.  This year I got my medical set and needed some time with an instructor to get the feel back for the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am back in the saddle after 7 hours with an instructor and the biennial flight review itself.&lt;/p&gt;&#xA;" OwnerUserId="12317" LastActivityDate="2015-11-16T21:28:43.010" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22965" PostTypeId="1" AcceptedAnswerId="22966" CreationDate="2015-11-16T22:00:20.773" Score="22" ViewCount="2119" Body="&lt;p&gt;First: I'm not a real pilot. I used an on-line flight planning tool, and in the brief was the following &quot;GPS NOTAM&quot;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;GPS 11/032 ZSE NAV (CHLK GPS 15-15) GPS (INCLUDING WAAS, GBAS, AND&#xA;        ADSB)MAY NOT BE AVAILABLE WITHIN A 476NM RADIUS CENTERED AT&#xA;        360822N1173846W (BTY214059) FL400-UNL DECREASING IN AREA WITH A&#xA;        DECREASE IN ALTITUDE DEFINED AS:&#xA;        432NM RADIUS AT FL250,&#xA;        375NM RADIUS AT 10000FT,&#xA;        340NM RADIUS AT 4000FT AGL,&#xA;        253NM RADIUS AT 50FT AGL.&#xA;        DLY 2130-2230&#xA;        1511172130-1511182230&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I must admit I don't understand most of this, but it seems like GPS is unavailable in what seems to be a huge inverted cone of space. What's going on here?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2017-05-18T00:38:04.540" Title="Why does this NOTAM make me think GPS is unavailable?" Tags="&lt;notam&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22966" PostTypeId="2" ParentId="22965" CreationDate="2015-11-16T22:13:39.760" Score="37" Body="&lt;p&gt;This outage is due to &lt;a href=&quot;http://www.navcen.uscg.gov/pdf/gps/gpsnotices/GPS_Interference.pdf&quot;&gt;department of defense GPS interference testing&lt;/a&gt; taking place 17-18 Nov 2015.  The interference generated may make the GPS signal unreliable and the outage cone described by NOTAM lets you know that you can't trust the GPS signal during this time.  This interference may be purposeful jamming or live testing of devices that may interfere with GPS to ascertain what level of interference occurs. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-11-16T22:13:39.760" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="22967" PostTypeId="2" ParentId="22227" CreationDate="2015-11-16T23:23:13.923" Score="8" Body="&lt;p&gt;It's very difficult to answer this question directly, mostly because that the costs you or I would face when undertaking such an endeavour are primarily capital in nature. For a large airline (or other organisation), they'd have staff and equipment on hand already, and the price an organisation like BA or BAE pay for parts is almost certainly different to the list price. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, the deal in question is &lt;a href=&quot;http://www.theguardian.com/business/2010/mar/30/airtanker-air-force-pfi-audit-office&quot;&gt;notoriously bad value for money&lt;/a&gt;. From that source, the taxpayer will be paying around £10.5 billion for 14 Airbus A330 troop transport/tanker jets with a capital value of only about £1 billion, although the deal also includes maintenance. Although converted to military specification, the converted passenger jets will not be flying into a war zone any time soon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, it appears that the government itself didn't really know the answer to 'how much will this cost', even as they were signing the contract to &lt;a href=&quot;https://www.nao.org.uk/report/ministry-of-defence-delivering-multi-role-tanker-aircraft-capability/&quot;&gt;provide new aircraft.&lt;/a&gt; Specifically, a critical report from the National Audit Office concluded that there was 'poor access to full cost data – the Department never gained visibility of detailed sub-contractor costs and margins for the aircraft and their modification'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, nobody knows!&lt;/p&gt;&#xA;" OwnerUserId="7499" LastActivityDate="2015-11-16T23:23:13.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22968" PostTypeId="2" ParentId="22961" CreationDate="2015-11-16T23:26:18.907" Score="9" Body="&lt;p&gt;This is indeed a designated air refueling track used by military tanker aircraft (all AR-nnn SUA areas are, and they all share that same general racetrack shape).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason why it isn't on a sectional is because it's simply not a concern to anyone who isn't in a high-performance, high-altitude airplane -- air refueling (of fixed-wing birds at least) typically takes place well into the FLs (FL280-FL330 is typical, although it may be lower or higher depending on what the tanker is gassing up), and doesn't bother anybody below.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-11-16T23:26:18.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22970" PostTypeId="1" AcceptedAnswerId="22974" CreationDate="2015-11-17T08:39:06.210" Score="21" ViewCount="4854" Body="&lt;p&gt;I've just read an article from SkyNews &lt;a href=&quot;http://news.sky.com/story/1588870/islamic-state-plotting-deadly-cyber-attacks&quot;&gt;just here&lt;/a&gt; where they said it's expected that one day air traffic control will be the target of cyber attacks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is &quot;Is ATC connected to the Internet and why ?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they just connected (if they are) to exchange information between the various ATC Centers and in this case I think they use VPN connections with military grade encryption or do they use Internet for other reasons ?&lt;/p&gt;&#xA;" OwnerUserId="11131" LastEditorUserId="19" LastEditDate="2015-11-18T07:07:12.207" LastActivityDate="2015-11-18T07:07:12.207" Title="Is ATC connected to the Internet &amp; why?" Tags="&lt;air-traffic-control&gt;&lt;security&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22971" PostTypeId="2" ParentId="22970" CreationDate="2015-11-17T11:25:47.137" Score="8" Body="&lt;p&gt;You'd be surprised what's connected to the internet. I've been an information security consultant for more than a decade and every time I think I've seen it all I see new levels of foolishness. I would not expect ATC systems to be directly accessible from the internet as that's a very bad idea, but I would not be surprised if it came to light that someone had been dumb enough to do it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you don't have to have systems directly connected to the internet for them to be vulnerable to attack, in fact they don't have to be connected at all. Attackers go after protected targets by gaining a foothold on internet connected systems and using them as jumping off points to other systems. An attacker could be a single person, a small group, or a large, state-sponsored hacking organization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A very common scenario is that an attacker infects users' personal computers by sending them malware (a virus, trojan horse, worm, etc) in an email, or emailing links to websites which have been compromised. The malware infects a user's computer using vulnerabilities in the operating system or installed applications and allows the attacker to access that computer in a way that the user cannot detect. Once the attacker owns the user's PC he/she can then sniff around the network and compromise other systems, again using vulnerabilities in operating systems and/or applications. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of ATC an attacker could, with the right expertise and resources, penetrate and map out critical ATC computer infrastructure to the point where it could be widely disrupted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What ATC organizations should be doing is the same as all other organizations which are targets, for example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;patching their systems to make them harder to hack&lt;/li&gt;&#xA;&lt;li&gt;running regular penetration tests, where professional &quot;white hat&quot; hackers find security holes before the bad guys do&lt;/li&gt;&#xA;&lt;li&gt;training staff to be aware of suspicious emails&lt;/li&gt;&#xA;&lt;li&gt;protecting ATC systems using firewalls, two-factor authentication, brokered administration, and other controls&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-17T11:25:47.137" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="22972" PostTypeId="5" CreationDate="2015-11-17T11:39:44.360" Score="0" Body="&lt;p&gt;For an introduction to turbulence in relation to aviation, see &lt;a href=&quot;http://aviation.stackexchange.com/questions/2554/what-is-turbulence-and-how-does-it-happen&quot;&gt;What is turbulence, and how does it happen?&lt;/a&gt; . The &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbulence&quot; rel=&quot;nofollow&quot;&gt;Wikipedia page on Turbulence&lt;/a&gt; is about turbulent flow in all of physics, not specifically about air turbulence in aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/wake-turbulence&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wake-turbulence&amp;#39;&quot; rel=&quot;tag&quot;&gt;wake-turbulence&lt;/a&gt; for artificial turbulence created by the wake of another aircraft (you almost never need to use both tags together)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/wind&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wind&amp;#39;&quot; rel=&quot;tag&quot;&gt;wind&lt;/a&gt; for large-scale movements of air which aren't necessarily turbulent&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/aerodynamics&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aerodynamics&amp;#39;&quot; rel=&quot;tag&quot;&gt;aerodynamics&lt;/a&gt; for how aircraft interact with the air in general&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;/questions/tagged/mountain-flying&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;mountain-flying&amp;#39;&quot; rel=&quot;tag&quot;&gt;mountain-flying&lt;/a&gt;, an activity where turbulence is common&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-11-17T12:14:29.580" LastActivityDate="2015-11-17T12:14:29.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22973" PostTypeId="4" CreationDate="2015-11-17T11:39:44.360" Score="0" Body="Questions about air turbulence, clear air turbulence, or other air movements that cause loss of control and discomfort in flight" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2015-11-17T12:14:41.907" LastActivityDate="2015-11-17T12:14:41.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22974" PostTypeId="2" ParentId="22970" CreationDate="2015-11-17T12:04:14.213" Score="16" Body="&lt;p&gt;The Air Traffic Control system does transmit information over the internet. The Air Traffic Control system has a number of components, some of which transmit information over the internet. According to &lt;a href=&quot;https://www.oig.dot.gov/library-item/29916&quot; rel=&quot;noreferrer&quot;&gt;Review of Web Applications Security and Intrusion Detection in Air Traffic Control Systems&lt;/a&gt;, Office of Inspector General, DoT,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;..Federal Aviation Administration (FAA) has increasingly turned&#xA;  toward the use of commercial software and Internet Protocol (IP) -based&#xA;  technologies to modernize ATC systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the ATC is not connected directly to the internet. It is the behind scene connections, that are routed through the internet. According to &lt;a href=&quot;http://news.discovery.com/tech/cyber-attack-air-traffic.htm&quot; rel=&quot;noreferrer&quot;&gt;a security professional&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... when most managers say there is no connection to the Internet, they are unaware of maintenance connections. Behind the scenes there are almost always semi-direct connections through routers shared between the control system and business systems that can be exploited&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Actually, the use of internet for sharing of information is increasing. &lt;a href=&quot;https://www.faa.gov/nextgen/&quot; rel=&quot;noreferrer&quot;&gt;FAA's NextGEN&lt;/a&gt; modernization involves a significant amount of information transmission over the internet. According to US &lt;a href=&quot;http://www.gao.gov/products/GAO-15-370&quot; rel=&quot;noreferrer&quot;&gt;Government Accountability Office&lt;/a&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NextGen is a modernization effort begun in 2004 by FAA to transform the&#xA;  nation’s ground-based ATC system into a system that uses satellite-&#xA;  based navigation and other advanced technology. ... These&#xA;  new technologies will use an Internet Protocol (IP) based network to&#xA;  communicate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/03xq4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/03xq4.jpg&quot; alt=&quot;NextGEN&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from GAO report on Air Traffic Control&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This increasing connection to the internet does increase the associated risks. From the same GAO report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the shift to NextGen technologies will require FAA to replace its proprietary, relatively isolated ATC computer systems with information systems that interoperate and share data throughout FAA’s operations and those of its aviation partners. ... These new systems...will also employ digital and Internet-based computer-networking technologies, exposing the air traffic control (ATC) system to new cybersecurity risks.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As to why the ATC is connected to the internet, it basically boils down to ease of operation. According to [NATS], which manages UK airspace,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We ... are now working all over the world within an industry where systems are connected across organisations, countries and continents. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Such an interconnected worldwide system requires a standard platform, which will not be possible (or atleast very difficult to maintain) if a closed, proprietary platform is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, the ATC does use internet, though this is mainly to transmit information. However, I'm not aware of the security systems, though we can be sure that they do have some sort of encryption (If I'm correct, Lockheed Martin supplies the software) and have firewalls to protect the systems.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-17T12:04:14.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22975" PostTypeId="2" ParentId="21633" CreationDate="2015-11-17T16:58:21.177" Score="3" Body="&lt;p&gt;This occurs pretty frequently in the GA community as apps like &lt;a href=&quot;http://foreflight.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ForeFlight&lt;/a&gt; are quickly becoming the preferred method of navigation in small and even larger planes. There are a few problems that need to be overcome and ill outline them here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Offline&lt;/strong&gt;: Since you wont have access to the internet in the air you will need to cache the maps offline. There are lots of apps out there that do this in a variety of ways for a variety of reasons. Some are for hiking, others driving, and many for flying specifically. &lt;a href=&quot;http://foreflight.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ForeFlight&lt;/a&gt;, &lt;a href=&quot;https://itunes.apple.com/us/app/fltplan-go/id694832363?mt=8&quot; rel=&quot;nofollow noreferrer&quot;&gt;FltPlanGo&lt;/a&gt;, and &lt;a href=&quot;https://buy.garmin.com/en-US/US/on-the-go/apps/garmin-pilot-/prod115856.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Garmin Pilot&lt;/a&gt; are just some of the ones that allow offline flight maps to be stored. Some of these apps require expensive subscriptions but they ensure that your data is always legal and up to date. If you are not a pilot &lt;a href=&quot;https://itunes.apple.com/us/app/fltplan-go/id694832363?mt=8&quot; rel=&quot;nofollow noreferrer&quot;&gt;FltPlanGo&lt;/a&gt; (free) is a cool one to check out. Flight based apps will also allow you to see cool info related to your flight like weather, approach plates and overlay over airspace maps instead of traditional road maps. ForeFlight even knows when you land and will pull up the airport diagram for you! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Global_Positioning_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;GPS&lt;/a&gt;&lt;/strong&gt;: One of the major problems you will have is the GPS chip thats internal to the device. On one hand you have the fact that the airplane is a giant &lt;a href=&quot;https://en.wikipedia.org/wiki/Faraday_cage&quot; rel=&quot;nofollow noreferrer&quot;&gt;faraday cage&lt;/a&gt; as mentioned in other answers. This prevents you from getting a decent signal but even if you can get a good signal you will be plagued by the not so great GPS chip in most phones. &lt;a href=&quot;http://ipadpilotnews.com/2015/10/ipad-frequently-asked-questions/&quot; rel=&quot;nofollow noreferrer&quot;&gt;This Article&lt;/a&gt; goes over it nicely &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When using the iPad with only the internal GPS in your lap in the cockpit, we’ve found that the GPS tended to lose signal reception intermittently. Sometimes the iPad will not lock onto GPS again until you reboot your iPad. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;but in general I have found the iPhone and iPad GPS to be less than optimal when I'm flying even small GA planes at far slower speeds. One of the best solutions to this is to get an &lt;a href=&quot;http://gps.dualav.com/explore-by-lifestyle/aviation/xgps160-for-efb-apps-new/&quot; rel=&quot;nofollow noreferrer&quot;&gt;external GPS receiver like this one&lt;/a&gt; they are small and provide great reception at all altitudes. Granted its a bit pricy just to know where you are on a commercial flight but it will do what you need it to.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fSqQv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fSqQv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.expansys-usa.com/dual-skypro-gps-receiver-for-ipad-android-tablets-black-red-xgps-160-252679/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;INS&lt;/a&gt;&lt;/strong&gt;: Your other option (and most airliners actually use this to navigate in some capacity) is to rig up a simple inertial navigation system with your phone. The issue this will induce is that you wont really be able to use your phone unless you don't move it. Using this method you can use the internal accelerometers to measure acceleration and calculate velocity in all 3 dimensions and inevitably deduce position from all that. There is at least &lt;a href=&quot;https://play.google.com/store/apps/details?id=com.olympio.inav&amp;amp;hl=en&quot; rel=&quot;nofollow noreferrer&quot;&gt;one android app&lt;/a&gt; I can find that does it or you can (if you so chose) &lt;a href=&quot;http://hackaday.com/2013/07/31/an-introduction-to-inertial-navigation-systems/&quot; rel=&quot;nofollow noreferrer&quot;&gt;write your own&lt;/a&gt;. Along with not being able to move your phone INS systems also suffer from compounding errors which make them increasingly inaccurate as time goes on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dead_reckoning&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dead Reckoning&lt;/a&gt;&lt;/strong&gt;: This is one of ways pilots are taught to navigate and to some extent you could do it from your seat with a stopwatch, compass and map. If you know what plane you are on and you know its approximate speed (based on published numbers) you could compute your path. Practically speaking you will also need to know the winds aloft since your compass will read out the way the nose of the plane is pointing not the way its moving over the ground. Aloft you can easily have winds in excess of 50Kts or even 100Kts, if thats a direct crosswind your heading and ground track will be substantially different. As long as you know what the winds aloft are (For the US they can be found &lt;a href=&quot;https://aviationweather.gov/products/nws/winds/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;) you can fill in the blanks. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-17T16:58:21.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22977" PostTypeId="2" ParentId="22970" CreationDate="2015-11-17T18:53:43.680" Score="6" Body="&lt;p&gt;Short answer: &lt;strong&gt;It's complicated&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not personally an authority on this subject, but I can point to some information the FAA has released.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;System Wide Information Management &lt;a href=&quot;http://www.faa.gov/nextgen/programs/swim/&quot; rel=&quot;noreferrer&quot;&gt;(SWIM)&lt;/a&gt; is the network structure that will carry &lt;a href=&quot;http://www.faa.gov/nextgen/programs/&quot; rel=&quot;noreferrer&quot;&gt;NextGen&lt;/a&gt; digital information. SWIM will enable cost-effective, real-time data exchange and sharing among users of the National Airspace System.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;NextGen is the ongoing modernization of the US National Airspace System, so this describes the current plan. Note that controllers are one user group of the National Airspace System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Security controls are defined in FAA Order 1370.114 - &quot;Implementation of FAA Telecommunications Infrastructure Services and IS Requirements in the NAS&quot;. This document is not public.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;FAA Telecommunications Infrastructure (FTI) NAS Boundary Protection System (NBPS) User’s Guide Volume II- For Non-NAS Users&quot; &lt;a href=&quot;https://www.faa.gov/nextgen/programs/swim/documentation/media/user-guide/FTI_NBPS_User_Guide.pdf&quot; rel=&quot;noreferrer&quot;&gt;(document)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;provides  guidance  to  external  system  owners  for  provisioning  IP-based  service connectivity  to  a  National  Airspace  System  (NAS)  system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Included is this figure:&lt;a href=&quot;https://i.stack.imgur.com/Et3tB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Et3tB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;My head! It's SWIMMING in acronyms...&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.faa.gov/nextgen/programs/swim/documentation/media/demo_proto/WMSCR%20SWIM%20Netcentric%20Presentation.pdf&quot; rel=&quot;noreferrer&quot;&gt;WMSCR&lt;/a&gt; (Weather Message Switching Center Replacement System): Collects, processes, stores, and disseminates textual aviation weather products and NOTAM information.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.tc.faa.gov/its/cmd/visitors/data/ACT-300/warp.pdf&quot; rel=&quot;noreferrer&quot;&gt;WARP&lt;/a&gt; (Weather and Radar Processor): An enroute weather system that provides Mosaiced Next Generation Weather Radar (NEXRAD) information to air&#xA;traffic controllers via the Display System Replacement (DSR) and provides meteorological products to the Center Weather Service Unit (CWSU) meteorologists and Traffic Management Specialists (TMU).&lt;/li&gt;&#xA;&lt;li&gt;NMR (National Airspace Data Interchange Network (NADIN) Message Switching Network (MSN) Rehost): Transmits flight plans. &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/cip/files/fy15-19/fy15-19_cip_complete_aug_2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;(source)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(gotta love the embedded acronyms.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it depends on what you consider &quot;ATC&quot;. These are critical systems that support controllers and others. They are 'connected to the internet', albeit through many layers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, according to &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/data_mgmt/faq/&quot; rel=&quot;noreferrer&quot;&gt;this page&lt;/a&gt;, updated 10 Jan 2013, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is the FAA's intent to terminate point to point (local) connections between FAA NAS systems and outside entities as soon as possible and to replace them with connections made via secure gateway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...implying that there are (or were) (more) direct connections into certain FAA networks, which are being overhauled with the plan described above.&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Conclusion&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;There are many aspects of ATC. One would speculate that systems such as primary and secondary radar are appropriately sand-boxed internally. But clearly certain systems are in some fashion exposed to the internet, at least to expose data for use by others.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-11-17T18:53:43.680" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22978" PostTypeId="1" AcceptedAnswerId="22979" CreationDate="2015-11-17T19:04:36.663" Score="10" ViewCount="2265" Body="&lt;p&gt;Wind shear is defined as a sudden change in the speed or direction of the wind with altitude.  There's got to be some ratio of speed to altitude or directional change to altitude beyond which it's defined as shear, but I can't figure out what it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the actual change in wind direction or speed over altitude for a wind shift to become considered wind shear?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-11-17T21:16:44.667" Title="What wind change gradient is necessary to be classified as wind shear?" Tags="&lt;wind&gt;&lt;windshear&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22979" PostTypeId="2" ParentId="22978" CreationDate="2015-11-17T19:11:13.107" Score="8" Body="&lt;p&gt;On one hand this has to do with how wind shear is actually reported which makes it tough to put an official value on it some times. Wind shear is often reported by pilots when they experience it on landing, takeoff or in the air. This may come in as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilot_report&quot; rel=&quot;nofollow noreferrer&quot;&gt;PIREP&lt;/a&gt; and be disseminated out to other pilots. When you are actually in the left seat you will see the manifestation of wind shear as a sudden loss of airspeed or severe weathervaning of the aircraft. There are many conditions that may cause a pilot to report wind shear. Since different planes at different times may experience different conditions its somewhat subjective. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Wind_shear&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia definition&lt;/a&gt; puts it at:   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airplane pilots generally regard significant wind shear to be a horizontal change in airspeed of 30 knots (15 m/s) for light aircraft, and near 45 knots (22 m/s) for airliners at flight altitude. Vertical speed changes greater than 4.9 knots (2.5 m/s) also qualify as significant wind shear for aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/files/gslac/library/documents/2011/Aug/56407/FAA%20P-8740-40%20WindShear%5Bhi-res%5D%20branded.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The FAA has a nice briefing on it here&lt;/a&gt; and their definition (as official as its going to get) is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Frontal Wind Shear&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As with so many things associated with weather, there is no absolute&#xA;  rule, but a couple of clues tell you that wind shear may occur: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;The temperature difference across the front at the surface is 10 °F&#xA;  (5 °C) or more.&lt;/li&gt;&#xA;  &lt;li&gt;The front is moving at a speed of at least 30 knots.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Thunderstorm Wind Shear&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;These winds can change direction by as much as 180 degrees and reach&#xA;  velocities of 100 knots as far as 10 miles ahead of the storm. The&#xA;  gust wind speed may increase by as much as 50 percent between the&#xA;  surface and 1,500 feet, with most of the increase occurring in the&#xA;  first 150 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Temperature Inversion Wind Shear&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One particularly bothersome aspect of temperature inversion shears is&#xA;  that as the inversion dissipates, the shear plane and gusty winds move&#xA;  closer to the ground. In some areas of the Southwest, a 90-degree&#xA;  change in direction and 20- to 30-knot increases in surface winds in a&#xA;  few minutes are not uncommon&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wind Shear From Surface Obstructions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some airfields are close to mountain ranges, and mountain passes are&#xA;  close to the final approach paths. Strong surface winds blowing&#xA;  through these passes can cause serious localized wind shear during the&#xA;  approach. The real problem with such shear is that it is almost&#xA;  totally unpredictable in terms of magnitude or severity&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From personal experience low level wind shear can really do a number on small planes. Bigger planes with more mass will still be affected but less so from what I hear. I have seen speed drops of 15kts momentarily and heading shifts upwards of 30 degrees on final approach in a Piper Warrior in even light shear conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an overly dramatic (and personal favorite) rendering of a micro burst causing wind shear &#xA;&lt;a href=&quot;https://i.stack.imgur.com/Qq7A3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Qq7A3.jpg&quot; alt=&quot;Illustration of a microburst over an airport&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Wind_shear&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports (110 in the US so far) have been lucky enough to have &lt;a href=&quot;https://en.wikipedia.org/wiki/Low_level_windshear_alert_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Low Level Wind Shear Detection Systems&lt;/a&gt; installed which are pretty neat units, they will detect that as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;LLWAS wind shear alerts are defined as wind speed gain or loss of between 20 and 30 knots aligned with the active runway direction. &quot;Low level&quot; refers to altitudes of 2,000 ft (610 m) or less above ground level (AGL)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/langley/news/factsheets/Windshear.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is a pretty neat overview from NASA&lt;/a&gt; of the various methods to detect it in the air.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-17T20:43:57.887" LastActivityDate="2015-11-17T20:43:57.887" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="22980" PostTypeId="2" ParentId="22978" CreationDate="2015-11-17T19:23:28.913" Score="2" Body="&lt;p&gt;'Wind shear' isn't defined by a certain &lt;em&gt;gradient&lt;/em&gt;, but by the fact that there is a &lt;em&gt;change&lt;/em&gt; in wind speed or direction (not necessarily with altitude). When flying through a wind shift, you experience wind shear. The strength of the turbulence experienced when flying through changes in wind varies with the exact situation and size of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Pilot/Controller Glossary:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;WIND SHEAR - A change in wind speed and/or wind direction in a short distance resulting in a tearing or shearing effect. It can exist in a horizontal or vertical direction and occasionally in both.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Technically, 'short distance' could imply gradient, but for all practical purposes that is over-thinking the definition and I don't think this line exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/questions/22978/what-wind-change-gradient-is-necessary-to-be-classified-as-wind-shear/22980#comment53207_22980&quot;&gt;voretaq7 notes&lt;/a&gt;, 10kts of wind fluctuation within 2000 AGL is defined as an Urgent PIREP. There is not a time-window though, so a sufficiently loose definition of instantaneous is assumed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer the question: one that you can feel.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-11-17T21:16:44.667" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="22981" PostTypeId="2" ParentId="22891" CreationDate="2015-11-17T23:31:08.847" Score="0" Body="&lt;p&gt;Every forecast has a valid time, and in fact valid times are different for the same type of forecast in different locales , for example TAFs are valid for either 4 or 6 hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My answer, therefore, is that the valid time for ANY forecast is whatever the forecast itself says.  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-11-17T23:31:08.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22982" PostTypeId="2" ParentId="22970" CreationDate="2015-11-18T00:33:43.403" Score="4" Body="&lt;p&gt;ATC mostly rely on so-called operational network not directly connected to internet. As mentionned by &lt;a href=&quot;https://aviation.stackexchange.com/a/22974/3367&quot;&gt;aeroalias&lt;/a&gt; there are links between operational and business networks that might be vulnerable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a growing trend to interconnect systems to improve throughput, thus increasing exposure. Below is a scheme illustrating collaborative decision making on an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last but not least, ATC rely on wireless communication between control and planes, which is vulnerable to listening and spoofing. Not internet-based, but yet vulnerable to cyber-attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/VHGOs.jpg&quot; height=&quot;400&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;taken from &lt;a href=&quot;http://www.euro-cdm.org/concept_introduction.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.euro-cdm.org/concept_introduction.php&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3367" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-18T00:33:43.403" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22983" PostTypeId="1" AcceptedAnswerId="22987" CreationDate="2015-11-18T03:44:01.847" Score="72" ViewCount="13619" Body="&lt;p&gt;In many non-English speaking countries, communication with ATC may be conducted either in English or the native language. Famous examples are China, Russia, France and possibly Germany. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a pilot who is a non-speaker of the native language hears such communication, which is he to do? Just sit back with no idea of what is going on?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="1542" LastEditDate="2015-11-19T15:17:49.027" LastActivityDate="2015-11-22T17:49:36.133" Title="What happens if a language other than English is used over the radio?" Tags="&lt;radio-communications&gt;" AnswerCount="6" CommentCount="8" FavoriteCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="22984" PostTypeId="2" ParentId="16612" CreationDate="2015-11-18T03:48:50.207" Score="2" Body="&lt;p&gt;So unlike the answers that were here first, I say that the short version is that &quot;out in the real world&quot;, it doesn't work that way.... except in some situations that are commonly seen as an air traffic controller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a pilot is given a descent, with no additional instructions, we will typically descend either at a constant rate of descent or a constant airspeed.  The AIM says that we should descend at an optimum rate (not the maximum rate) until within 1000 feet of the assigned altitude, and then no more than 1500 fpm for that last 1000 ft.  Depending on my distance from the destination or other expected crossing restriction, I typically choose a descent rate between 1500 and 2500 fpm and use power to maintain my target descent airspeed.  When using this method, the descent rate will not increase with speed, however my vertical flight path angle will change as the speed changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The behavior that you describe is most likely seen when a crossing restriction is issued to the pilot, or they are planning to cross a self-made crossing restriction (10,000 ft. AGL at 30nm from the airport is commonly used).  This effectively fixes the vertical flight path angle, and now the only way to compensate for speed changes is to adjust the vertical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When descending from high altitudes (above 30,000ish feet, depending on the airplane), the indicated airspeed will increase with a constant Mach number, until the target descent airspeed is reached, and vertical speed must be increased in order to compensate for the higher ground speed in order to make the crossing restriction.  On the other hand, if a speed reduction is assigned then the descent rate may be reduced in order to make the same crossing restriction (or the aircraft just reaches it's assigned altitude early, which is not normally an issue).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This adjustment happens either automatically (by the FMS / autopilot in VNAV mode), or is monitored and manually adjusted by the pilot in order to meet the crossing restrictions.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-11-18T05:18:05.073" LastActivityDate="2015-11-18T05:18:05.073" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22985" PostTypeId="2" ParentId="22983" CreationDate="2015-11-18T03:59:54.507" Score="14" Body="&lt;p&gt;Basically, yes.  This is also common in most of the Spanish speaking countries that I have flown within that are in the Americas, as well as French being predominately used in France.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In each of these places it is very common to hear ATC speaking to many (most) of the pilots in their native tongue, and speak English only when talking to someone that doesn't speak it. (Sometimes with a very strong and hard to decipher accent.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I prefer being able to hear everything (sometimes you can catch things that you might not otherwise), but that's just the way that it works.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2015-11-18T03:59:54.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22986" PostTypeId="2" ParentId="22983" CreationDate="2015-11-18T04:22:01.043" Score="47" Body="&lt;p&gt;This is much more common than just the countries you list.  In Mexico, for example, ATC communications with Mexican carriers are entirely in Spanish and many of the controllers have thick accents. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully, ATC phraseology is standardized and limited in vocabulary so it isn't too difficult to get the basic idea of what is going on.  If you pick up on the words for &quot;left&quot;, &quot;right&quot;, &quot;climb&quot;, &quot;descend&quot; and the numbers you'll maintain a good idea of what other airplanes around you are doing.  The corollary to this is the controllers often get by in English the same way.  I once tried to report an un-tethered balloon floating up near our position and going &quot;off-script&quot; made it hard to communicate.  In the end an AeroMexico pilot translated what we were saying to the controller in Spanish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing you &lt;em&gt;don't&lt;/em&gt; want to do is decide, once you've learned the words for &quot;hello&quot;, &quot;good morning&quot;, etc, is to use those during your initial callup to foreign ATC.  It might sounds nice to say &quot;Buenos dias Monterrey, jetlink treinta treinta-dos nivel do veulo tres siete cero&quot; but  it'll backfire on you when the controller responds in Spanish.  This is doubly true in Canada where the controllers (particularly over Québec) are quite happy to service you in French.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="995" LastEditDate="2015-11-18T20:03:21.173" LastActivityDate="2015-11-18T20:03:21.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22987" PostTypeId="2" ParentId="22983" CreationDate="2015-11-18T04:34:03.917" Score="136" Body="&lt;p&gt;During the 1990s I flew into countries on every continent except Antarctica. As an American English speaker flying U.S. registered airplanes, I never had a complaint that a controller had trouble understanding me, and I was always addressed in English by the controllers. Sometimes, though, I would have trouble understanding the controller's accent and would have to ask them to repeat their instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you mentioned, in some countries the controllers will address the pilots of that country in their native language. Personally, I always felt that compromised the smooth functioning of the system to a degree, because it denied a good bit of the overall picture of what was happening to the pilots who didn't speak that language. For example, if two airplanes preceding you are being rerouted for some reason, but you can't understand what they've been given (and which you're probably going to be given), you're not as prepared for the reroute when it comes through to you in English.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if controllers spoke to you in English, they would typically pronounce place names and fixes as they are pronounced in the native language. My first flights in France were a real problem in this respect. The French controllers were speaking good and understandable English, but the French pronunciation of the place names did not match our English rendition of the names we were seeing (and had never seen or heard before) on the IFR maps (no glass cockpits back then for us). In a couple of instances, we had to request that they spell the names, which didn't make us popular. On one occasion, when we made such a request, another pilot came on frequency and said, &quot;He means ....&quot; and gave us an English transliteration if you will of what the controller was saying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the worst time I ever had understanding a clearance was one from a nominally English speaking controller. We were talking to Scottish control, and received a reroute into Amsterdam from a controller with a very pronounced accent (Glaswegian?). All I was able to get was that at the end he was turning us over to Dutch control and the frequency. I went over to the Dutch, and asked for them to restate what our new clearance was, and I apologized, explaining that I had been unable to understand Scottish control. His first words were, &quot;That's okay, we can't understand them either.&quot;&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-11-18T04:34:03.917" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="22988" PostTypeId="2" ParentId="12782" CreationDate="2015-11-18T05:31:51.077" Score="2" Body="&lt;p&gt;Normal single or even twin rudder won't work with a flying wing. This is due to a length/wingspan ratio. Normal aircraft have a length/wingspan ratio of more than 1. Flying wing on the other hand have the ratio of less than 1. To solve this problem, the designer either have to enlarge the rudder or add more rudder. Up to 4 in YB-49 for example. But this enlarge or added rudder also provide added drag, thus negating the low-drag advantage the flying wing are suppose to give. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For rudderless design, the problem is yaw stability. to provide yaw control, rudderless aircraft use some sort of differential braking system. The problem is, this system doesn't provide static stability like a rudder provide. To create some semblance of yaw stability, the differential braking system have to be adjusted regularly for the entire duration of a flight. Done manually, this would've tire the pilot quickly. So a rudderless aircraft require some form of autonomous FCS to handle this. This automated system account for the extra cost and added an extra point of failure. This limit the usage of this kind of design to a military only and not the cost conscious commercial airliners.&lt;/p&gt;&#xA;" OwnerUserId="12323" LastActivityDate="2015-11-18T05:31:51.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22989" PostTypeId="1" AcceptedAnswerId="22990" CreationDate="2015-11-18T05:51:19.730" Score="1" ViewCount="806" Body="&lt;p&gt;After a research, I've seen prototypes of planes with elevators. What if it could be used as part of the &quot;Air Ambulance&quot; technology on helicopters? Because helicopters have to land first to pick up patients, would it be better to use an &quot;elevator&quot; to lift them into the helicopter when it is hovering?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this have been made before, can you point to a prototype? &#xA;And if not, why it haven't been made? Is it non-doable in terms of physics and engineering?&lt;/p&gt;&#xA;" OwnerUserId="12324" LastEditorUserId="12220" LastEditDate="2015-11-19T01:12:39.277" LastActivityDate="2015-11-19T01:12:39.277" Title="Can a helicopter have a fully mechanic &quot;elevator&quot;?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-11-18T12:40:39.603" ContentLicense="CC BY-SA 3.0" />
  <row Id="22990" PostTypeId="2" ParentId="22989" CreationDate="2015-11-18T08:02:42.907" Score="1" Body="&lt;p&gt;Using a building elevator would cut the payload of the helicopter in an unacceptable way. Also, none of the safety features of a building elevator could be implemented, and in the end you will have a cage lowered on a rope. Which is quite similar to existing winch systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JlgVc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JlgVc.jpg&quot; alt=&quot;Elevator components&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elevator components (&lt;a href=&quot;http://3.bp.blogspot.com/-AH1TSx3Dl_w/T4RlER5BPyI/AAAAAAAABmM/-SuvOQ3lcsw/s1600/main+components+of+elevator.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the motor and the pulleys, a building elevator has a car which runs along guide rails, and a counterweight to compensate for the heavy car. Adding all this to a helicopter would require a much bigger machine just for carrying the elevator components around. Note that using guide rails would dictate a specific hover height - no helicopter pilot would agree to have his options restricted that severely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lowering anything in the downwash of a helicopter rotor will cause it to swing and rotate, and putting the occupants into a cage will cut their ability to stabilize themselves or the cage. Once the cage is raised all the way up, it needs to be oriented correctly for easy egress. A rescuer on a rope can easily stabilize himself by grabbing handles on the outside of the helicopter. Sitting in a cage, he can only watch helplessly when the cage arrives in the wrong orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many scenarios where rescue helicopters cannot land, like over water or over a &lt;a href=&quot;http://www.abc.net.au/news/2012-01-04/helicopter-rescues-rock-climber-in-sa27s-morialta-conservation/3758576&quot; rel=&quot;nofollow noreferrer&quot;&gt;forest&lt;/a&gt;. In those situations a &lt;a href=&quot;http://utcaerospacesystems.com/cap/products/Pages/rescue-hoists-cargo-winches.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;winch&lt;/a&gt; is used to hoist one rescuer down to the ground, where he/she can pick up the injured and secure them to their harness. Both of them are then raised up and taken on board. Only when the patient must not move (think fractured leg), a platform is used to secure the patient. See below for a simulator installation, and note that still a rescuer is needed to stabilize the platform.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j141a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j141a.jpg&quot; alt=&quot;Helicopter rescue hoist trainer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopter rescue hoist trainer (&lt;a href=&quot;http://www.amst.co.at/typo3temp/_processed_/csm_A-42_RHT-Bad-Toelz-011_0fe7583b6a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the ground allows, landing the helicopter is simpler, makes much less noise and makes it immune to changing winds. Also, lowering the rescuer first and landing the helicopter will take a similar amount of time, so no substantial time savings can be expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hd9Fb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hd9Fb.jpg&quot; alt=&quot;AW139 helicopter on SAR exercise&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AgustaWestland AW139 helicopter on SAR exercise (&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/4/44/AW139_Helicopter_on_Search_and_Rescue_Exercise_MOD_45151098.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-18T08:40:34.910" LastActivityDate="2015-11-18T08:40:34.910" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22991" PostTypeId="2" ParentId="22983" CreationDate="2015-11-18T08:42:40.060" Score="9" Body="&lt;p&gt;The ATC will repeat to you whatever he deems necessary for you to know. All transmissions &quot;to all stations&quot; will be also in English. Private pilots may not even posses the aviation English certificate (it is an optional extra course in our country) and they still want to be able to fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are a pilot of a small airplane yourself, it may even happen to you that the  AFIS or RADIO station at the local airport doesn't have the English certificate and will not be allowed to advise you in English.&lt;/p&gt;&#xA;" OwnerUserId="3189" LastEditorUserId="3189" LastEditDate="2015-11-22T17:49:36.133" LastActivityDate="2015-11-22T17:49:36.133" CommentCount="3" CommunityOwnedDate="2015-11-18T08:42:40.060" ContentLicense="CC BY-SA 3.0" />
  <row Id="22992" PostTypeId="2" ParentId="22957" CreationDate="2015-11-18T14:00:44.117" Score="6" Body="&lt;p&gt;Assuming that &quot;flight school hours&quot; means flight time then &lt;a href=&quot;http://www.caa.co.uk/application.aspx?catid=33&amp;amp;pagetype=65&amp;amp;appid=11&amp;amp;mode=detail&amp;amp;id=6412&quot; rel=&quot;noreferrer&quot;&gt;CAP 804&lt;/a&gt; suggests yes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;3.6 Logging of Flight Hours gained in the USA&lt;/strong&gt;   Some flight hour recording practices allowable in the USA do not comply with European&#xA;  and UK requirements. In particular:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;2 pilots flying together in a single pilot aircraft both claiming P1    hours; &lt;/li&gt;&#xA;  &lt;li&gt;One pilot accompanying another on newsgathering or traffic    control flights and claiming P1/PIC when they have not acted as Captain or signed for the aircraft.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;Flying hours of this nature cannot be credited towards the&#xA;  requirements for Part-FCL or UK Licences.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The last sentence implies that if hours logged in the US &lt;em&gt;do&lt;/em&gt; comply with &quot;European and UK requirements&quot; then they can be credited towards licenses. If you need something more detailed and explicit then it may be easiest to ask the CAA directly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-11-18T14:00:44.117" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="22994" PostTypeId="2" ParentId="22983" CreationDate="2015-11-18T16:25:10.630" Score="0" Body="&lt;p&gt;In Brazil, ATCos communicate on their native language (Portuguese) or in English. If you do not speak English, it will not be recommended do fly across your boundaries.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-11-18T16:25:10.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22995" PostTypeId="1" CreationDate="2015-11-18T16:42:36.157" Score="5" ViewCount="660" Body="&lt;p&gt;When pilots face a sudden depressurization, they will follow some procedures.&#xA;What are their sequences and if there is any addressed to the cabin crew?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="247" LastEditDate="2015-11-18T17:26:32.577" LastActivityDate="2015-11-18T17:26:32.577" Title="What procedures will cockpit crew follow during a sudden depressurization?" Tags="&lt;safety&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22996" PostTypeId="2" ParentId="22995" CreationDate="2015-11-18T16:57:08.673" Score="9" Body="&lt;p&gt;In the EMB-145 I flew, the procedure for rapid depressurization was:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                   RAPID CABIN DEPRESSUIZATION&#xA;&#xA;         Aural Warning                    Condition&#xA;         ━━━━━━━━━━━━━               ━━━━━━━━━━━━━━━━━━━━&#xA;         Voice Message            CABIN ALTITUDE INDICATION&#xA;            &quot;CABIN&quot;               HAS EXCEEDED 10,000 FT AND&#xA;                                        BECOMES RED&#xA;┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓&#xA;┃ Crew Oxygen Masks ........................................ DON ┃&#xA;┃ Crew Communication ................................. ESTABLISH ┃&#xA;┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛&#xA;&#xA;  Passenger Oxygen ................................. AS REQUIRED&#xA;  Maximum Altitude .......................... MEA OR 10,000 FT.,&#xA;                                             WHICHEVER IS HIGHER&#xA; ┏━━┓&#xA; ┃IF┃  Emergency Descent Required:&#xA; ┗━━┛  ATC .............................................. NOTIFY&#xA;       Emergency Descent Procedure ..................... PERFORM&#xA;&#xA;                              * * *&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The priority is getting your O2 mask on and then make sure the other pilot was able to get his on as well and help if needed.  The passenger O2 will automatically deploy if the cabin altitude gets high enough but you can force deployment from the cockpit.  If the depressurization is rapid and/or sudden an emergency descent will be performed to get down into breathable atmosphere ASAP (&lt;a href=&quot;https://aviation.stackexchange.com/a/8559/258&quot;&gt;regulatory requirement time limit&lt;/a&gt;).  In the case of emergency descent our procedure did have a PA to make sure everyone was seated and seat belted for the maneuver.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin crew will have their own procedures and while I'm not familiar with them they are equipped with portable oxygen cylinders and have the ability to move around the cabin and assist passengers with masks.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-11-18T17:14:49.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="22998" PostTypeId="1" CreationDate="2015-11-18T17:14:41.857" Score="13" ViewCount="2321" Body="&lt;p&gt;I have read and seen some articles in which, for various reasons, the aircraft's nose gear collapsed after landing during the roll out. This resulted in the aircraft going off the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to still control the aircraft during this weird event? Or is it more or less inevitable that the aircraft will run off the runway?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="62" LastEditDate="2015-11-18T17:41:41.940" LastActivityDate="2015-11-26T02:39:53.093" Title="Is it possible to control an aircraft on the runway if the nose gear collapses?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="22999" PostTypeId="2" ParentId="22998" CreationDate="2015-11-18T18:17:46.037" Score="4" Body="&lt;p&gt;To an extent, yes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most importantly you can also control the airplane using differential braking of the rear wheels. This is how planes with a &lt;a href=&quot;http://www.avweb.com/news/features/Flying-The-Nosewheel-223233-1.html&quot; rel=&quot;nofollow&quot;&gt;free castering nose wheel are steered on the ground&lt;/a&gt;.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note if the plane is moving fast enough and their is sufficient airflow over the rudder you may be afforded limited control of the aircraft via the rudder. However as the speed decreases (your nose is presumably dragging on the ground at this point) your rudder will lose authority and differential braking would be the way to go. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-18T18:30:59.703" LastActivityDate="2015-11-18T18:30:59.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23000" PostTypeId="2" ParentId="22998" CreationDate="2015-11-18T18:20:26.983" Score="20" Body="&lt;p&gt;Most aircraft are steered on the ground by pivoting the nose gear. If the nose gear collapses, you therefore lose your primary method of directional control on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, parts of the aircraft contacting the ground that are not supposed to contact the ground can cause unwanted &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_principal_axes#Vertical_axis_.28yaw.29&quot; rel=&quot;nofollow&quot;&gt;yaw&lt;/a&gt;, which can contribute greatly to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway_safety&quot; rel=&quot;nofollow&quot;&gt;runway excursions&lt;/a&gt; you've noticed in articles regarding gear collapse incidents. This is probably the largest contributing factor to runway excursions in cases of nose gear collapse. However, if it's known that the nose gear did not deploy properly before the landing, the pilots can intentionally hold the nose gear off the ground as long as possible in order to minimize this effect. Holding the nose gear off the ground as long as possible minimizes the time that the contact between the nose and runway surface will be potentially applying yawing forces to the aircraft and also minimizes the speed of the aircraft while those forces are being applied. This gives the pilots more time to respond with differential braking and/or rudder, helping to prevent the nose from moving too far away from the direction of travel and a resulting loss of directional control due to skidding. Of course, this doesn't help if the gear collapse was unexpected, as the pilots wouldn't know to hold the nose gear up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few additional methods of directional control available to airplanes on the ground, though most are not as effective as pivoting the nose gear and their effectiveness varies with speed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Rudder - While the aircraft still has high airspeed when rolling down the runway, the rudder will still provide some directional control. This control will diminish very rapidly as the aircraft slows down, though.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Asymmetric braking - Most airplanes allow the pilots to control the brakes on the left and right main gear independently, allowing them to brake harder on one side of the aircraft than on the other. This is more useful for taxi speeds than for high speeds down a runway, though, and can easily cause even more directional control problems if used without proper care at high speeds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Asymmetric thrust - Multi-engine aircraft almost always allow the pilots to control the thrust (either forward or reverse) of each of the engines independently. However, in the case of a collapsed gear, this is unlikely to be very helpful, due to the large delay between when a thrust change is commanded and when it happens as well as that the engines may now also be striking the ground themselves.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-11-26T02:39:53.093" LastActivityDate="2015-11-26T02:39:53.093" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23001" PostTypeId="2" ParentId="22998" CreationDate="2015-11-18T18:21:24.577" Score="3" Body="&lt;p&gt;Differential braking would still be available for directional control, and the rudder would still be effective at the same speeds as normal (effectiveness decreasing as speed decreases).  To what extent one would have the presence of mind to use differential braking after the perhaps unexpected collapse of the nose gear is a question.  If the engines (assuming a multi-engine aircraft) weren't affected by the gear collapse, differential power would also be an option, although that's not always something that can be fine-tuned, and again would require the presence of mind to use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe there was a Jet Blue aircraft that landed in LAX a few years ago with a nosegear that, while not collapsed, was useless by virtue of being cocked sideways.  My recollection is that they stopped fairly well centered on the runway, although they had the advantage of knowing the situation in advance and working out a plan for exactly what they had.  So one might conclude that an operative nosewheel steering isn't essential to staying on the runway, but there's not much doubt that it certainly helps.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-11-18T18:21:24.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23002" PostTypeId="2" ParentId="19213" CreationDate="2015-11-18T19:06:41.493" Score="3" Body="&lt;p&gt;For the US, the FAA &lt;a href=&quot;https://nfdc.faa.gov/xwiki/bin/view/NFDC/56DaySub-2015-06-25&quot; rel=&quot;nofollow&quot;&gt;National Flight Data Center (NFDC)&lt;/a&gt; is the place. There is this set of files: &lt;em&gt;Class B,C,D,E Airspace Shape Files&lt;/em&gt;, which is free and contains borders of airspaces in the GIS &lt;a href=&quot;https://en.wikipedia.org/wiki/Shapefile&quot; rel=&quot;nofollow&quot;&gt;shapefile&lt;/a&gt; format.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2015-11-18T19:06:41.493" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23003" PostTypeId="2" ParentId="22998" CreationDate="2015-11-18T21:53:16.803" Score="18" Body="&lt;p&gt;There is nothing wrong with all answers here, but one aspect is missing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the nose gear collapses, the instinctive reaction of most pilots would be to brake as much as possible. Forget reverse thrust or spoilers - the pilot will hit the brakes. If pressure builds up slightly differently between left and right brake, or if the wheel load between both main landing gears is different due to cross wind, the aircraft will experience asymmetric braking, and now the nose will not be exactly centered between both main wheels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we need to look at the braking forces of the skidding front fuselage in comparison to those of the main wheels. Since the aircraft has now a pronounced nose-down attitude, its load on the nose will be quite a bit higher than the regular load on the nose landing gear used to be. With the increased load on the front fuselage, its scratching along the concrete will contribute a lot to the braking force, and if this force is off-center it will produce a yawing moment that can be balanced only initially and with full application of differential braking. Once the front fuselage has sverved beyond the tracks of the main gear, no braking will bring it back into the center and the aircraft is uncontrollable. Add some crosswind and it will leave the runway quickly.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible to still control the aircraft during this weird event?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Applying rudder will still help at high speed, but once the aircraft slows down and the rudder becomes less effective, the aircraft is uncontrollable.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Or is it more or less inevitable that the aircraft will run off the&#xA;  runway?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Only in perfectly symmetrical conditions will it stay on the runway. Since the aircraft with the collapsed nose gear is unstable in yaw, the far more likely outcome is a runway excursion.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-18T22:00:43.427" LastActivityDate="2015-11-18T22:00:43.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23004" PostTypeId="1" CreationDate="2015-11-18T23:35:41.590" Score="0" ViewCount="2061" Body="&lt;p&gt;I don't quite understand the various categories of Class E airspace. &lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-11-19T15:59:37.127" Title="What are the types of class E airspace?" Tags="&lt;airspace&gt;&lt;class-e-airspace&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-08-26T09:14:17.937" ContentLicense="CC BY-SA 3.0" />
  <row Id="23005" PostTypeId="1" CreationDate="2015-11-18T23:39:48.020" Score="6" ViewCount="194" Body="&lt;p&gt;I'm part of a High Altitude Ballooning club. Our main goal for this year is to achieve controlled descent of our payload. We plan to use Magnus force cylinders to go about this. I have found nothing in FAA documentation that specifically mentions something of this sort requiring extra clearance, but am still somewhat worried about putting the payload 100,000 feet up and then dropping it down in a controlled manner without being absolutely certain, as an object falling out of the sky in a directed manner could obviously garner concern if people didn't realize what it was. Does anyone know if there are specific regulations for this sort of thing, and whether there are or not, what should I look into doing? Thanks for the help&lt;/p&gt;&#xA;" OwnerUserId="12337" LastEditorUserId="1467" LastEditDate="2016-05-25T10:36:24.190" LastActivityDate="2016-05-25T10:36:24.190" Title="What are the FAA regulations concerning controlled descent of a light payload?" Tags="&lt;descent&gt;&lt;high-altitude&gt;&lt;balloon&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23006" PostTypeId="2" ParentId="23004" CreationDate="2015-11-18T23:41:11.003" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Class E Airspace&#xA;  If the airspace is not Class A, B, C, or D, and is controlled &#xA;  airspace, then it is Class E airspace. Class E airspace extends &#xA;  upward from either the surface or a designated altitude to the &#xA;  14-3&#xA;  Figure 14-2.&#xA;  An example of a prohibited area is Crawford, Texas.&#xA;  overlying or adjacent controlled airspace. When designated &#xA;  as a surface area, the airspace is configured to contain all &#xA;  instrument procedures. Also in this class are federal airways, &#xA;  airspace beginning at either 700 or 1,200 feet above ground &#xA;  level (AGL) used to transition to and from the terminal or &#xA;  en route environment, and en route domestic and offshore &#xA;  airspace areas designated below 18,000 feet MSL. Unless &#xA;  designated at a lower altitude, Class E airspace begins at &#xA;  14,500 MSL over the United States, including that airspace &#xA;  overlying the waters within 12 NM of the coast of the 48 &#xA;  contiguous states and Alaska, up to but not including 18,000 &#xA;  feet MSL, and the airspace above FL 600.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can find more about it here: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-18T23:41:11.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23007" PostTypeId="2" ParentId="23004" CreationDate="2015-11-18T23:42:10.720" Score="6" Body="&lt;p&gt;Check out &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this publication from the FAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class E airspace extends&#xA;  upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated&#xA;  as a surface area, the airspace is configured to contain all&#xA;  instrument procedures. Also in this class are federal airways,&#xA;  airspace beginning at either 700 or 1,200 feet above ground&#xA;  level (AGL) used to transition to and from the terminal or&#xA;  en route environment, and en route domestic and offshore&#xA;  airspace areas designated below 18,000 feet MSL. Unless&#xA;  designated at a lower altitude, Class E airspace begins at&#xA;  14,500 MSL over the United States, including that airspace&#xA;  overlying the waters within 12 NM of the coast of the 48&#xA;  contiguous states and Alaska, up to but not including 18,000&#xA;  feet MSL, and the airspace above FL 600.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This image may help to visualize it &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hf1pe.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hf1pe.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.cfinotebook.net/notebook/national-airspace-system/class-delta-airspace.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In more general terms its the airspace that covers most of the US below 18,000ft. Its the area where a lot of the General Aviation traffic lives (although some of it is making its way into the &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2008/September/1/Mooney-Acclaim-Type-S-A-Piston-Rocket&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight levels these days&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Side note&lt;/em&gt;: Depending on how you look at it class E airspace is bound to an upper limit of either 400,000 feet (76mi) which is what &lt;a href=&quot;https://en.wikipedia.org/wiki/Outer_space&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA considers re-entry altitude&lt;/a&gt; or what The Fédération Aéronautique Internationale defines as space starting at 62 miles so either one of those can be used as an upper bound for Class E (although officially the FAA does not define an upper bound). Re-entry point is where air drag comes into play so you would be hard pressed to get a plane over that altitude. Practically speaking the jet altitude record is held by the SR-71 Blackbird at 85,069ft and the Concorde pulls in at 60,039 ft for commercial flight. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-19T00:52:12.567" LastActivityDate="2015-11-19T00:52:12.567" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23008" PostTypeId="2" ParentId="23005" CreationDate="2015-11-18T23:54:12.950" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/AD2EBDA6370BB404852566CF0061287A?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA FAR says the following on the matter&lt;/a&gt;,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Sec. 91.15&lt;/p&gt;&#xA;&lt;p&gt;Dropping objects.&lt;/p&gt;&#xA;&lt;p&gt;No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As long as you take precautions not to hit anything you are ok. All things considered you are somewhat at the mercy of the FAA here, if something were to go wrong it would most likely be considered your fault.&lt;/p&gt;&#xA;&lt;p&gt;After some looking around there are some other things to consider. Since you are using Magnus Force Cylinders to control the decent depending on how you look at it these can be considered a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8cc463a703baa53d725aea0251bd16df&amp;amp;mc=true&amp;amp;node=se14.1.1_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&amp;quot;Parachute&amp;quot; by the FAA definition&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Parachute&lt;/em&gt;: means a device used or intended to be used to retard the fall of a body or object through the air.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Likewise what you are doing may also be considered a &amp;quot;Parachute Drop&amp;quot;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Parachute Drop&lt;/em&gt;: means the descent of an object to the surface from an aircraft in flight when a parachute is used or intended to be used during all or part of that descent.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Another interesting point is that from 100,000 ft you will be busting through the Class A airspace here in the US (and likely class E). For that you may want to read up on &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8cc463a703baa53d725aea0251bd16df&amp;amp;mc=true&amp;amp;node=se14.2.105_125&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;parachuting in controlled airspace&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Again similar to the dropping, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8cc463a703baa53d725aea0251bd16df&amp;amp;mc=true&amp;amp;node=se14.2.105_15&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;parachuting must be done with caution&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§105.5   General&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;No person may conduct a parachute operation, and no pilot in command of an aircraft may allow a parachute operation to be conducted from an aircraft, if that operation creates a hazard to air traffic or to persons or property on the surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Again a lot of this is open to interpretation, since you have no (presumed) way of controlling the vehicle on the decent I would say it does not fall under what the &lt;a href=&quot;https://www.faa.gov/uas/faq/#qn1&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA considers a UAS/UAV&lt;/a&gt;. You may want to reach out to the FAA directly about doing something like this from the kinds of altitudes you intend to.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-19T00:42:46.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23009" PostTypeId="1" AcceptedAnswerId="23015" CreationDate="2015-11-19T00:13:31.307" Score="27" ViewCount="31362" Body="&lt;p&gt;I have heard that propellers with more than four blades are not as efficient as 4 or less blades because of lower thrust which may result from interfering prop-streams. But I see the ATR-42/72 and they have 6 blades. What is the reasoning and the advantages to that prop layout?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-16T00:29:37.830" LastActivityDate="2018-12-25T00:21:11.347" Title="What are the advantages of more than 4 propeller blades?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;&lt;efficiency&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="23011" PostTypeId="1" AcceptedAnswerId="23026" CreationDate="2015-11-19T05:00:52.887" Score="9" ViewCount="1063" Body="&lt;p&gt;The U-2 spyplane was shot down over Russia in 1960 and over Cuba in 1962, both times by a radar-tracking missile. Why wasn't it equipped with any chaff to throw off the missile?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chaff is just a cloud of aluminum particles that return a big radar blur, masking the real craft so it can get away. The missile would home in on the chaff instead since it's a big juicy radar target. Chaff can be stored in very small cylinders near the tail of the plane, and the radar lock warning would let the pilot use it at the right time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Chaff was invented in World War 2, giving plenty of time all the way to the sixties. So why wasn't this airplane equipped with chaff?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="15311" LastEditDate="2017-11-24T22:07:30.903" LastActivityDate="2017-11-24T22:07:30.903" Title="Why didn't the U-2 spyplane have any chaff?" Tags="&lt;military&gt;&lt;radar&gt;&lt;reconnaissance-aircraft&gt;&lt;lockheed-u2&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23012" PostTypeId="1" CreationDate="2015-11-19T05:21:08.943" Score="2" ViewCount="293" Body="&lt;p&gt;What examples of failures in Janitrol heaters can be found in NTSB reports?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a bit of background, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gasoline_heater&quot; rel=&quot;nofollow noreferrer&quot;&gt;gasoline heater&lt;/a&gt; is a small, gasoline-fueled heating device commonly found in light twin aircraft such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_414&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 414&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'd like to do is compile a list of the associated NTSB reports for all known failures of Janitrol heaters that caused an incident. I'd also like to note which cases had a favorable result and what actions the pilots took to handle the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer may eventually lead to a discussion of depressurizing the cabin of pressurized aircraft to put out a fire. While this approach won't work with some fires, it might apply to this situation. &lt;a href=&quot;https://aviation.stackexchange.com/q/391/8490&quot;&gt;This question about in flight fire&lt;/a&gt; is relevant to that discussion.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-11-19T05:21:08.943" Title="What examples of Janitrol heater failures can be found in NTSB reports?" Tags="&lt;safety&gt;" AnswerCount="0" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23013" PostTypeId="2" ParentId="23011" CreationDate="2015-11-19T06:00:42.960" Score="9" Body="&lt;p&gt;At the time, it was believed that no missile could hit the U2 at 70,000 feet although this was more a belief driven by overconfidence and arrogance.  When the U2 was designed this was true and there was simply no need to fit countermeasures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following this incident, flights over Russia were stopped.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flights over Cuba were made in the belief that there were no SAMs and of course, it was a U2 that captured the photographs which showed the Soviet deployments there.  Overflights were then stepped up to gather as much intelligence as possible whilst accepting the risk of being intercepted.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-19T06:24:51.197" LastActivityDate="2015-11-19T06:24:51.197" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23014" PostTypeId="1" AcceptedAnswerId="23052" CreationDate="2015-11-19T06:52:50.833" Score="5" ViewCount="402" Body="&lt;p&gt;The airfield I learned to fly helicopters at is in uncontrolled airspace and has an air/ground radio service only.  It has a main runway, 07/25 and a secondary runway only used in high x-winds, 13/31.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gHUiR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gHUiR.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All fixed wing circuits are to the North so fixed wings will fly right hand circuits when operating Westerly and left hand circuits when operating on the Easterlies.  Helicopter circuits are always to the South so the reverse is true.  This works well and keeps fixed wing traffic separated from helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, there is no &quot;dead side&quot; since the Southern leg is the downwind for rotary and the Northern leg is downwind for fixed wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once, when preparing for take off from runway 25, I heard a call from a fixed wing announcing they were about 7 miles to the East and would &quot;join dead side&quot;.  The A/G operator reminded the pilot, who clearly wasn't one for reading the relevant publications, that there is no dead side and advised them to make a standard overhead join.  We were operating to the West so my circuit would be left hand to the South.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next call I heard from them was on the downwind leg when the pilot announced &quot;descending dead side&quot;.  The operator reminded them that there was no dead side and more insistently instructed an overhead join.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am now at 1,000 feet on my downwind with an aircraft I suspect is in front of me heading towards me and descending!  Referring to the plate, I am heading roughly East to the South of the road marked &quot;A303&quot; at the bottom of the plate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I took 3 actions;  I made a position call of &quot;downwind South&quot;, increased my height to 1,200 (I figured they were likely to have joined at 1,000 feet) and switched on the landing light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find any rules of the air or rules of thumb to help in this situation.  Are there any?  Is there anything else I should have done to help to avoid a conflict?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I never did see the other aircraft and I knew from the pilots actions and their lousy use of the radio that they were inexperienced or incompetent and I didn't go looking for them when I was back on the ground to &quot;share a little wisdom&quot; with them.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="19" LastEditDate="2016-07-28T16:49:15.050" LastActivityDate="2016-07-28T16:49:15.050" Title="What are the rules for &quot;see and be seen&quot; when you suspect a potential conflict in class G airspace?" Tags="&lt;general-aviation&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23015" PostTypeId="2" ParentId="23009" CreationDate="2015-11-19T07:53:37.863" Score="36" Body="&lt;p&gt;You are right, more blades are bad for &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383#15383&quot;&gt;efficiency&lt;/a&gt; (follow the link for the definition). &lt;a href=&quot;https://aviation.stackexchange.com/questions/21354/possible-to-fly-with-counterbalanced-single-blade-engines/21358#21358&quot;&gt;Ideally, a propeller should have only one blade&lt;/a&gt;. Every additional blade will cause disturbances which interfere with the flow on the other blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When engine power increases, the propeller disc area should also grow, but this growth is limited by the resulting speed of the blade tips. Once the flow speed there becomes supersonic, the drag at this section of the blade increases without a corresponding increase in thrust. To avoid that, the next best option is to increase the solidity ratio of the propeller, called also the &lt;a href=&quot;http://quest.arc.nasa.gov/qna/questions/Propellers_Activity_Factor.htm&quot; rel=&quot;noreferrer&quot;&gt;activity ratio&lt;/a&gt;. This is done by either increasing blade chord or the number of blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make no mistake, this is bad for efficiency. But if there is enough power available, adding more blades is the best way to transform that engine power into thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take the Supermarine Spitfire:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The prototype, powered by the 1,030 hp &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Merlin&quot; rel=&quot;noreferrer&quot;&gt;Rolls-Royce PV-12&lt;/a&gt;, had a two-bladed propeller&lt;/li&gt;&#xA;&lt;li&gt;From the Mk II, a three-bladed propeller was fitted to accommodate the increasing power of the RR Merlin (1,470 hp for the Spitfire Mk V).&lt;/li&gt;&#xA;&lt;li&gt;With the &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire_(late_Merlin-powered_variants)#Mk_IX_.28type_361.29&quot; rel=&quot;noreferrer&quot;&gt;Mk IX&lt;/a&gt;, a four-bladed propeller was needed for the 1,575 hp of the supercharged Merlin 61.&lt;/li&gt;&#xA;&lt;li&gt;From the &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire_(Griffon-powered_variants)&quot; rel=&quot;noreferrer&quot;&gt;Mk XII&lt;/a&gt;, the more powerful Rolls-Royce Griffon made a five-bladed propeller necessary. Engine power was raised from 1,735 hp to 2,300 hp for the last variant, the Mk XXIV.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cdxEM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cdxEM.jpg&quot; alt=&quot;Rolls-Royce Griffon-powered Supermarine Spitfire&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rolls-Royce Griffon-powered Supermarine Spitfire (picture &lt;a href=&quot;http://www.simplyplanes.co.uk/images/pages_images/classic_aircraft/bbmf/photos_used_on_main_page/spitfire_ps915_1_photo.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lower prop speed allows to increase its diameter, but while tip speed will drop by less than the reduction in prop speed (after all, flight speed should not change), the available thrust from this propeller will drop by the square of the speed reduction, since thrust is proportional to the dynamic pressure on the blades. And thrust you get only from the circumferential fraction of the local speed at the blade; flight speed does not count here and does not help to mitigate the reduction. Consequence: You cannot make the propeller bigger and spin it more slowly for a given power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An extreme example for a propeller with a high activity ratio is the &lt;a href=&quot;http://en.aerosila.ru/index.php?actions=main_content&amp;amp;id=32&quot; rel=&quot;noreferrer&quot;&gt;Aerosila SV-27&lt;/a&gt; contra-rotating propeller of the &lt;a href=&quot;http://ivchenko-progress.com/?portfolio=d-27&amp;amp;lang=en&quot; rel=&quot;noreferrer&quot;&gt;D-27 propfan engine&lt;/a&gt; powering the &lt;a href=&quot;http://www.cthomas.de/an_70.htm&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-70&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dWO8G.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dWO8G.jpg&quot; alt=&quot;SV-27 propellers on the An-70&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SV-27 propellers on the An-70 (picture &lt;a href=&quot;http://farm4.staticflickr.com/3268/3911157885_1b499d08b7_z.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Eight blades in the forward disc and six in the rear, running at only 1200 RPM. In order to reduce Mach effects, all blades have a swept tip and deep chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can only be topped by something like an &lt;a href=&quot;https://aviation.stackexchange.com/questions/13837/given-the-same-engine-why-install-a-gearbox-on-a-turboprop-but-not-on-a-turbofa/13839#13839&quot;&gt;ungeared turbofan with a ducted propeller&lt;/a&gt;. A turbofan, in other words.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-11-20T21:48:43.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23016" PostTypeId="1" AcceptedAnswerId="23035" CreationDate="2015-11-19T09:32:14.857" Score="9" ViewCount="1260" Body="&lt;p&gt;If the Smolensk disaster was to be traced down to a single decision (other than attempting landing in the first place), it would probably be the choice of radio altimeter to control altitude over a very unfortuitously shaped terrain (a wide valley, with steep slopes). This made the airplane to descend to 80 meters above the bottom of the valley, instead of 80 meters above the runway located 60 meters higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone mapped the black box recordings of the navigator's altitude readouts to speed and terrain profile, interpreting them as barometric altimeter readouts and it came out as an unreasonably bumpy ride (the orange line). I tried to follow up with mapping these same readouts at the same intervals, but relative to ground surface - treating them as radio-altimeter readouts - and it follows the blue line; judge for yourself which can depict a large passenger plane trajectory more accurately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MH9ig.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MH9ig.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An unbiased comparison would include both advantages and disadvantages of the two types of altimeters. In this specific case (unknown, uneven profile terrain) the one main disadvantage of the radio altimeter is obvious: it doesn't provide accurate information about altitude of the airplane relative to the runway. I wonder though, what redeeming properties does it have - what are the advantages (if any) of using a radio altimeter over a barometric altimeter during landing - any inherent flaws of the barometric altimeter, like accuracy, reaction speed, or such, in which one type excels over the other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(yes, I'm asking for a &lt;em&gt;biased&lt;/em&gt; comparison; one with focus on superiority of one of the other. I realize both have their correct applications, both have strengths and weaknesses, applications where one or the other is better. Here I'm specifically asking for one side of this argument; half of the full image; look at it not as &quot;why is A better than B&quot; but &quot;which traits of A are better than B&quot;)&lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="22726" LastEditDate="2019-01-24T01:29:28.997" LastActivityDate="2019-01-24T01:29:28.997" Title="How accurate is the barometric altimeter in the Tu-154?" Tags="&lt;instrument-flight-rules&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23017" PostTypeId="1" AcceptedAnswerId="23027" CreationDate="2015-11-19T10:57:58.233" Score="6" ViewCount="670" Body="&lt;p&gt;I'm watching a documentary about daily business of an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was a crew briefing for a Lufthansa flight from Germany to India, and as there was an Indian FA, the briefing was held in English (i.e. he didn't speak German).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it is advantageous to have an Hindi speaking FA on board of a flight to India, I wonder why he doesn't speak German.&#xA;To me, it seems unusual to have an employee living here, but not speaking our language. (Though this is possible.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question is:&#xA;Do airlines employ people &lt;em&gt;in&lt;/em&gt; their destination countries, for example to have FAs speaking the language of the destination country? Or is there some kind of exchange project?&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="5517" LastEditDate="2015-11-19T17:48:38.967" LastActivityDate="2015-11-19T19:50:10.480" Title="Do airlines employ FAs from their destination countries?" Tags="&lt;crew&gt;&lt;flight-attendant&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23018" PostTypeId="2" ParentId="23009" CreationDate="2015-11-19T11:18:42.597" Score="16" Body="&lt;p&gt;First, we have to define what is efficiency. In case of propeller, we can define efficiency as the ratio of output power (ability of the propeller to produce a given thrust at a given airspeed) and input power (i.e. the shaft power of the engine).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All else held constant, the efficiency the propeller decreases as the number of blades increase due to aerodynamic reasons (like interference). However, if the engine power is increased, the propeller should be able to 'absorb' that; i.e. transmit engine power to the air flow passing through the propeller disk, adding energy and generating thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the engine power is increased, there are a number of ways to make the propellers absorb it, each with is own share of issues:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Increase angle of attack&lt;/em&gt; i.e. blade pitch- The pitch angle is usually set at a value where the aerodynamic efficiency is optimal. Changing it may make the blade inefficient.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Increase the blade diameter&lt;/em&gt; The causes two major problems- Longer blades means more tip speed, which increases drag once it reaches transonic speeds; also, the longer blades means longer landing gear for tip clearance or more clearance between two propellers and/or fuselage. This increased structural weight is unacceptable as leads to a vicious cycle. An extreme case of this is the F4U Corsair, which had an inverted gull wing to accommodate the huge three bladed propeller required for the extremely powerful engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Increase the rpm&lt;/em&gt; The problem is again the tip speed, which can increase drag significantly at high speeds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Redesign the blade with more camber&lt;/em&gt; Again, the blades are usually at their optimal aerodynamic efficiency; increasing the camber may lead to less efficient blades.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Increase the chord&lt;/em&gt; This increases the solidity, improving efficiency; however, this leads to increased interference between the blades, which is again bad.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Increase the number of blades&lt;/em&gt; This is usually the solution adopted for reasons above. The blades may become inefficient, but the system is able to produce more thrust with minimum impact (like maintenance etc.). As &lt;a href=&quot;http://hartzellprop.com/faq/technical-questions/&quot; rel=&quot;noreferrer&quot;&gt;Hartzell says&lt;/a&gt;,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...efficiency doesn’t propel the airplane, thrust does&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A good example of the effect of the engine power on the number of propeller blades can be seen in the case of Lockheed Martin C130 Hercules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The initial model, the C-130A used a three bladed propeller to absorb the 4050 shp of Allison T56-9 turboprops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/miq38.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/miq38.jpg&quot; alt=&quot;C 130A&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: commons.wikimedia.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later models used a four bladed propeller as the engine power was increased to 4590 shp in Allison T56-A-15 turboprops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/16YgG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/16YgG.jpg&quot; alt=&quot;C 130H&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: planespotters.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-130J Super Hercules uses a 6 bladed propeller to absorb the 4,637 shp from Rolls-Royce AE 2100D3 turboprop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xavuR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xavuR.jpg&quot; alt=&quot;C 130J&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: theaviationgroup.eu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In extreme cases like the Tu-95, contra rotating propellers had to be used to absorb the power from the engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UhDpb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UhDpb.jpg&quot; alt=&quot;Tu 95&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airplane-pictures.net&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="14897" LastEditDate="2016-10-11T22:37:37.660" LastActivityDate="2016-10-11T22:37:37.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23019" PostTypeId="2" ParentId="23017" CreationDate="2015-11-19T11:27:41.513" Score="7" Body="&lt;p&gt;Airlines do employ people in their destination countries for a variety of tasks, both customer-oriented (such as gate agents and baggage handlers), as well as administrative and/or operational (such as station managers, maintenance staff, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, with respect to flight and cabin crew, things can get a bit more complex. Generally speaking, crew are hired and certificated in the country where the carrier is based out of (and, incidentally, certificated to perform air transportation operations for hire), and would have to follow local employment and, potentially, immigration legislation should they wish to hire foreign nationals; certain countries may make exceptions to these rules for airlines and the transportation industry, making it easier to hire staff with the necessary language skills, but this is by no way a given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With respect to FAs, major carriers make an effort to staff their cabins with FAs that speak the local language when travelling to international destinations. The FA might not have spoken German, but in addition to English, he might have also spoken Hindi, or any number of regional languages spoken in India, thus allowing the crew a greater probability of having &lt;em&gt;someone&lt;/em&gt; who can can converse with &lt;em&gt;any&lt;/em&gt; passenger on the flight.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2015-11-19T11:27:41.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23020" PostTypeId="1" CreationDate="2015-11-19T12:31:17.653" Score="13" ViewCount="1520" Body="&lt;p&gt;The TCAS warning says: &quot; DESCEND, DESCEND&quot; and immediately after the crew receives: &quot;TERRAIN, TERRAIN&quot;, what would they do?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-11-19T20:50:27.187" Title="When receiving a TCAS RA, DESCEND DESCEND, and starting the descent, if a pilot received GPWS warning, TERRAIN, what would they do?" Tags="&lt;tcas&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23022" PostTypeId="2" ParentId="23020" CreationDate="2015-11-19T12:56:38.463" Score="7" Body="&lt;p&gt;I would pull up and once in a stable climbs I would turn in either direction in this situation. If I get a warning to descend it is to prevent a conflict with another aircraft, whereas a terrain warning is to prevent impact with the ground. The ground is much bigger than another airplane, so the lower risk is collision with an aircraft. In other words, if I descend I will certainly hit the ground, if I climb I may hit another aircraft, so climbing wins. Turning in either direction will hopefully decrease the collision risk. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would suspect this is an unlikely situation, TCAS should not give an instruction which would put you into another conflict. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-19T12:56:38.463" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23023" PostTypeId="2" ParentId="23020" CreationDate="2015-11-19T13:08:04.757" Score="12" Body="&lt;p&gt;TCAS (II) does not give the descend RA below 1200 ft AGL while climbing or below 1000 ft AGL while descending.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5y8KE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5y8KE.png&quot; alt=&quot;TCAS Inhibits&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-151A.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Advisory Circular 20-151A&lt;/a&gt; Table 2&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case such an unlikely event happens (and is not an equipment malfunction), the best possible maneuver is to climb away from the incoming aircraft i.e. turn and climb to the side of the previous route.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-11-19T20:50:27.187" LastActivityDate="2015-11-19T20:50:27.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23024" PostTypeId="1" CreationDate="2015-11-19T13:32:02.840" Score="6" ViewCount="541" Body="&lt;p&gt;Reading some reports, about the failure of crew members to fully understand the fault on engines, rarely, but it happens, the crew can misjudge the engine on fire, shutting down the good one. On airlines where you fly, is there any standard procedure to avoid this event, I mean, shutting the good engine, instead of the bad one?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-11-23T11:47:28.057" Title="Is there any cockpit procedure used to avoid shutting the good engine, instead of the bad one (on fire, for example)?" Tags="&lt;safety&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23025" PostTypeId="2" ParentId="23024" CreationDate="2015-11-19T13:40:52.173" Score="4" Body="&lt;h2&gt;Procedures exist&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If you read about the &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Kegworth_air_disaster#Shutting_down_the_wrong_engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kegworth crash&lt;/a&gt; you will see that the pilot started to follow a procedure he has been trained on but was interrupted by an ATC call and failed to complete the procedure. The procedure involves checking the engine vibration meters and reviewing decisions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, yes, procedures exist.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Procedures vary&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Procedures vary depending on exact aircraft model and on the airline operating the aircraft. Some airlines use more memory checklists than other airlines. So it isn't possible to list a specific procedure that is used by all pilots of multi-engined aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Identifying problems&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Pilots don't start from the point &quot;we need to shut down engine No 2&quot; they start from some observable event like &quot;smoke in the cockpit&quot; (as in the example incident above)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are instruments on the instrument panel that show engine temperatures, vibration and other parameters that should usually make it evident which engine is not performing normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an example procedure - note that this isn't the one for the airline and plane model in the incident above but it is probably similar&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aHJr0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aHJr0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DSvad.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DSvad.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the points&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Eliminates No 2 engine as source ...&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;li&gt;Eliminates No 1 engine as source ...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-11-20T12:12:12.650" LastActivityDate="2015-11-20T12:12:12.650" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23026" PostTypeId="2" ParentId="23011" CreationDate="2015-11-19T13:45:10.870" Score="16" Body="&lt;p&gt;There are two main reasons for this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;USAF and CIA believed that the Russians (or anyone else) wouldn't be able to shoot down aircraft operating at (&gt;60000ft).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Most of the aircraft operating during that time did not have chaff dispensers to deploy chaff as needed. For that to work, the pilot has to either visually acquire the missile or have a RWR, which became widely used only in the later stages of Vietnam War.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Another important reason is tactics. The chaff was not used in WWII in a tactical capacity i.e. to protect individual fighters, but to provide blanket coverage to bomber fleets. This practice continued well into the Vietnam War. For example, specialized aircraft (usually fighters) will dump chaff to provide a 'corridor' for following bombers. For an aircraft on reconnaissance mission, this is as good as advertising its presence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of aircraft in that era went without any countermeasures. For example, the English Electric Lightning carried no chaffs till its retirement in 80's. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-19T13:45:10.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23027" PostTypeId="2" ParentId="23017" CreationDate="2015-11-19T14:34:57.583" Score="10" Body="&lt;p&gt;The 747 carrier I retired out of had FAs based in New York and Tel Aviv, and were residents of their respective countries. The citizenship of the JFK FAs was not a factor insofar as I know as there were numerous green card holders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-stop flights between JFK and Tel Aviv (and return, of course) were staffed by Israeli FAs. All other flights were staffed by JFK FAs. The primary reason for this arrangement was cultural. For JFK/TLV the back quarter or so of the aircraft was allocated to Hasidics to attempt to satisfy their preferences. For example, no movies were shown in the back because they were objectionable to the Hasidics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage of having Israeli FAs on the direct flights was that they knew how to handle the Hasidics. Scheduling problems would occasionally result in JFK FAs operating a JFK/TLV flight. It was not uncommon on such flights for the cabin crew to request a cockpit crew member to come back to help mediate a dispute. I never received such a request from an Israeli cabin crew.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2015-11-19T14:34:57.583" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23028" PostTypeId="2" ParentId="1906" CreationDate="2015-11-19T17:03:19.910" Score="6" Body="&lt;p&gt;There is one thing that previous answers completely missed. It is the simultaneous controlability of descent slope and descent speed. Any glider pilot (I am one of them) knows that there is a strong relationship betweeen slope and speed. This is why almost every glider have airbrakes, they allow some independant control of both parameters. For this the approach in a glider is made at a glide slope near 10:1 although except some very old gliders most of them have a best glide ratio higher than 30:1, which would be completely unpratical for landing. The combined action on airbrakes and pitch attitude with the elevator can be used to change airspeed on a fixed slope or to change slope while keeping the same airspeed, as long as the slope is high compared to best glide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a powered aircraft this control is obtained by adjusting power and pitch attitude. This requires the opposite to the glider case : the approach should be on a slope less than the best glide slope, the standard is 5%. This corresponds to nearly the best glide of a liner, so no correction would be possible. Of course an unpowered approach could and should be on a higher slope, but the lack of independance between slope and speed remains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know of 2 cases where the problem occured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fist one is known as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;noreferrer&quot;&gt;Gimli glider&lt;/a&gt;, a Canadian 767 that went out of fuel due to some miscalculation on the fuel at takeoff and landed on an unused airfield using slip instead of airbrakes to adjust the glide slope, as was done in older gliders with unefficient or no airbrakes, one of the pilots was an experienced glider pilot knowing this technique.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second one is probably the famous case of Sullenberger &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot; rel=&quot;noreferrer&quot;&gt;landing an Airbus on the Hudson river&lt;/a&gt;. Some people argued that he was in gliding range of two airfields when he took this decision. But the lack of possibility of precise control of the approach slope toward a runway with high buildings in the vicinity made probably the Hudson a better choice.&lt;/p&gt;&#xA;" OwnerUserId="12345" LastEditorUserId="753" LastEditDate="2015-11-20T11:26:40.607" LastActivityDate="2015-11-20T11:26:40.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23029" PostTypeId="1" CreationDate="2015-11-19T17:41:11.737" Score="4" ViewCount="445" Body="&lt;p&gt;Why is the planned &lt;a href=&quot;https://en.wikipedia.org/wiki/Kingdom_Tower&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kingdom Tower&lt;/a&gt; Skydeck unsuitable for use as a helipad? Originally the skydeck was supposed to be a helipad, but this idea was subsequently rejected and the feature was repurposed as a &quot;sky deck&quot; when it was discovered that it was not usable as a helipad, recalling another failed aviation docking boondoggle, the airship mooring mast on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Empire_State_Building&quot; rel=&quot;nofollow noreferrer&quot;&gt;Empire State Building&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nLnThm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nLnThm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/k3mkPm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k3mkPm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="15982" LastEditDate="2019-05-28T14:08:28.173" LastActivityDate="2019-05-28T14:08:28.173" Title="Why is the planned Kingdom Tower Skydeck unsuitable for use as a helipad?" Tags="&lt;landing&gt;&lt;helicopter&gt;&lt;wind&gt;&lt;helipad&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23031" PostTypeId="2" ParentId="23017" CreationDate="2015-11-19T17:56:49.970" Score="1" Body="&lt;p&gt;Yes, Swiss does it for their Tokyo destination.&lt;/p&gt;&#xA;" OwnerUserId="12346" LastActivityDate="2015-11-19T17:56:49.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23032" PostTypeId="2" ParentId="23016" CreationDate="2015-11-19T18:07:04.510" Score="-3" Body="&lt;p&gt;A radio altimeter is probably better because of its independence from weather-related pressure systems which barometric altimeters are really horrible at. There are many small pressure variations in a given area which the barometric one cannot compensate for all the time. The radio altimeter works batter in this area because a pilot would not need to reset it as often and when it encounters weather, it will not mess up.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-19T18:07:04.510" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23033" PostTypeId="2" ParentId="23029" CreationDate="2015-11-19T18:08:12.457" Score="9" Body="&lt;p&gt;A quote from The Guardian:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Starship Enterprise-like circular helipad, 30m across, protrudes out at level 157. This was originally designed to provide fast access to the penthouse, but &lt;strong&gt;the wind makes it a dangerous place to land&lt;/strong&gt;, so instead it has become an observation deck – the world’s highest at 630m.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theguardian.com/cities/2015/jun/04/jeddahs-kingdom-tower-how-much-higher-can-skyscrapers-go-a-history-of-cities-in-50-buildings-day-50&quot;&gt;link&lt;/a&gt; (emphasis by me)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopter prefers steady wind condition in order to land safely and comfortably. The nature of wind at such height is gusty and turbulent due to proximity to the building itself. It would be unsafe and very uncomfortable to the rich man who rides the chopper for 'quick access' to the penthouse on that floor. The highest helipad now is &lt;a href=&quot;http://www.ctbuh.org/LinkClick.aspx?fileticket=qH7LkIkhjQc%3D&quot;&gt;at 438 meters high&lt;/a&gt; at that is at the TOP of the building. &lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-11-19T18:08:12.457" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23035" PostTypeId="2" ParentId="23016" CreationDate="2015-11-19T19:32:40.657" Score="5" Body="&lt;p&gt;A barometric altimeter is required to meet certain operational standards for use in an aircraft under instrument flight rules. &lt;a href=&quot;https://aviation.stackexchange.com/questions/3727/how-precise-are-altimeters&quot;&gt;We talked a little about this in another question&lt;/a&gt; with references to the relevant FAA requirements for the instrument.&lt;br&gt;&#xA;I'm certain there's an equivalent in the Polish regulations, and while I don't know where you'd find it I would bet it's broadly similar in its requirements.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A radio/RADAR altimeter is typically accurate to within 20 feet &lt;em&gt;within its operating range&lt;/em&gt; (typically &amp;lt;= 2,500 feet AGL). There are varying TSOs for radio altimeters, so you'd have to look up the standard a specific unit was built to in order to get exact numbers.  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One of the core issues underlying this accident which you highlighted in your question is that a barometric altimeter and a radio altimeter are two different devices, measuring two different things, so it's not really reasonable to compare them.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Barometric altimeters&lt;/strong&gt; measure altitude above a standard reference (usually sea level) by using a known/standard pressure lapse rate (~1 in.Hg per 1,000 feet) and measuring the difference in pressure at the instrument.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The readings given by a barometric altimeter are affected by weather conditions (&lt;a href=&quot;https://aviation.stackexchange.com/questions/3495/is-the-altimeter-setting-corrected-for-temperature&quot;&gt;mainly temperature&lt;/a&gt;), so the displayed altitude may be 'incorrect' (relative to say GPS altitude above mean sea level).  &lt;/li&gt;&#xA;&lt;li&gt;The readings given by a barometric altimeter are not affected by the local terrain, so peaks, valleys, and tall buildings won't change what it shows.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Radio altimeters&lt;/strong&gt; measure the distance to whatever radio-wave-reflecting object is below the unit (typically &quot;the ground&quot; - whatever terrain happens to be under you) by detecting how long it takes a radio pulse to be reflected back.  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The radio altimeter reading is not affected by weather conditions (temperature) as these don't affect the pulse reflection time.&lt;/li&gt;&#xA;&lt;li&gt;The radio altimeter is affected by local terrain (peaks, valleys, etc.) as this changes the distance the radio pulse has to travel.&lt;/li&gt;&#xA;&lt;li&gt;The radio altimeter reading is affected by any object that reflects radio waves (buildings, other aircraft passing below you).&lt;/li&gt;&#xA;&lt;li&gt;The radio altimeter reading may be affected by &quot;slant range error&quot; &lt;a href=&quot;https://en.wikipedia.org/wiki/Distance_measuring_equipment#Accuracy&quot; rel=&quot;nofollow noreferrer&quot;&gt;just like DME&lt;/a&gt;, (in practical terms this is less of an issue for radio altimeters: The radio altimeter points &quot;straight down&quot; so the slant range error is generally small unless the aircraft's pitch or roll attitude is extreme).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So to directly answer your question, barometric and radio altimeters aren't comparable in the way you're asking: Because they measure two different things it's not possible to say one is &quot;superior&quot; to the other. They are different tools, serving different purposes: It's incumbent on the pilot to be aware of the limitations of whichever tool they happen to be using at the time (and to ensure that they've selected the correct tool for the task at hand).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-11-19T19:32:40.657" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23036" PostTypeId="2" ParentId="23017" CreationDate="2015-11-19T19:50:10.480" Score="1" Body="&lt;p&gt;Yes they do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My earlier flight this year on Hong Kong Airline from Hong Kong to Bangkok has FA who are Chinese and Thai. Cabin announcements were made in 3 languages, Chinese, English and Thai. &lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2015-11-19T19:50:10.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23037" PostTypeId="1" AcceptedAnswerId="23066" CreationDate="2015-11-19T19:52:47.997" Score="8" ViewCount="6281" Body="&lt;p&gt;Which airports consume the most fuel for aircraft refueling, and how much fuel do they use?   I was able to find that &lt;a href=&quot;http://www.theguardian.com/commentisfree/cif-green/2009/jun/09/labour-heathrow-runway&quot; rel=&quot;noreferrer&quot;&gt;&quot;Heathrow uses about 20m litres of fuel a day&lt;/a&gt;&quot;, but it isn't easy to find figures for other airports.&lt;/p&gt;&#xA;" OwnerUserId="12348" LastEditorUserId="12348" LastEditDate="2015-11-21T08:28:37.397" LastActivityDate="2018-03-15T12:40:33.750" Title="Which airports have the highest fuel upload?" Tags="&lt;airport&gt;&lt;refueling&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23038" PostTypeId="2" ParentId="23037" CreationDate="2015-11-19T20:00:11.210" Score="-4" Body="&lt;p&gt;Easiest way is just to look at the busiest airports in the world, they have the most planes flying in and out, therefore, they have to fuel more.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-19T20:00:11.210" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23039" PostTypeId="1" AcceptedAnswerId="23043" CreationDate="2015-11-19T20:18:38.790" Score="23" ViewCount="4176" Body="&lt;p&gt;In a comment on &lt;a href=&quot;https://aviation.stackexchange.com/a/23038/11953&quot;&gt;this answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airlines will tanker fuel if it's substantially cheaper at another airport&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I've wondered what that term meant before, and now this comment leads me to think that airliners will carry more fuel than what's required for a trip, because carrying the fuel might be cheaper than buying it at the next airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone provide more detail on why and when an airline might do this, the calculations that are involved, and any other interesting information on this topic?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="9401" LastEditDate="2019-11-14T21:18:33.980" LastActivityDate="2020-04-21T16:48:19.807" Title="What does the term &quot;tanker&quot; mean when used in regards to a passenger airliner?" Tags="&lt;terminology&gt;&lt;cost&gt;&lt;refueling&gt;&lt;tanker&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23040" PostTypeId="2" ParentId="23039" CreationDate="2015-11-19T20:26:50.307" Score="3" Body="&lt;p&gt;It basically means they will take on more fuel than necessary because the cost of doing so is cheaper than getting the fuel at the destination airport.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-19T20:26:50.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23041" PostTypeId="1" AcceptedAnswerId="23050" CreationDate="2015-11-19T20:30:45.407" Score="19" ViewCount="7619" Body="&lt;p&gt;When helicopters take off and land is it preferable to point the nose into the wind? Since a helicopter is providing its own lift does it matter which direction wind is coming from?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="19" LastEditDate="2017-08-10T09:54:23.103" LastActivityDate="2017-08-10T09:54:23.103" Title="Do helicopters try to take off and land into the wind?" Tags="&lt;helicopter&gt;&lt;wind&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23042" PostTypeId="2" ParentId="23039" CreationDate="2015-11-19T20:36:15.430" Score="14" Body="&lt;p&gt;&lt;em&gt;Tankering&lt;/em&gt; fuel means that an aircraft carries not only the fuel quantity required for the flight to the destination, but also the fuel, or a part of it, required for the next leg of the trip. The aircraft is therefore its own &lt;em&gt;tanker&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Tankering means reduced cost&lt;/h3&gt;&#xA;&lt;p&gt;This practice can be used when the difference in fuel price at departure and destination airports makes the operation less expensive than refueling at destination. The time to refuel can be also a factor. More: &lt;a href=&quot;https://www.sciencedirect.com/science/article/pii/S0969699718302692?dgcid=rss_sd_all&quot; rel=&quot;noreferrer&quot;&gt;The benefits of tankering considering cost index flying and optional refuelling stops&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;From the previous article:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel expenses remain one of the major components of an airline operational cost, depending on the aircraft size, it may approach from&#xA;20% up to 70% of its total flight cost.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel tankering has been studied and applied by airlines at least since the oil crisis in the 1970 decade. It has become an excellent&#xA;fuel saving strategy for airliners proving costs reductions up to 10%.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Example of price difference in Europe:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b70ip.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b70ip.png&quot; alt=&quot;Difference in fuel prices in Europe&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Difference in fuel prices in Europe, source &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/2020-01/eurocontrol-think-paper-1-fuel-tankering.pdf&quot; rel=&quot;noreferrer&quot;&gt;Eurocontrol&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Example of savings by fuel tankering:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iogln.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iogln.png&quot; alt=&quot;Savings by fuel tankering&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Savings by fuel tankering for airports distant by 300 NM. &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/2020-01/eurocontrol-think-paper-1-fuel-tankering.pdf&quot; rel=&quot;noreferrer&quot;&gt;Eurocontrol&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;How to read: For a round trip between airports distant by 300 NM, if fuel is 20% cheaper at the departure airport, then by performing a full tankering, 45 kg of additional fuel will be needed, but this will save 196 € (8%) for the round trip.&lt;/p&gt;&#xA;&lt;h3&gt;Tankering means also more CO&lt;sub&gt;2&lt;/sub&gt;&lt;/h3&gt;&#xA;&lt;p&gt;Tankering means burning more fuel than strictly required, this can provide an economical advantage, but this operation is usually not neutral for our environment, depending on how fuel is delivered to airports. From the study by &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/2020-01/eurocontrol-think-paper-1-fuel-tankering.pdf&quot; rel=&quot;noreferrer&quot;&gt;Eurocontrol&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[...] it  was  estimated  that  fuel  tankering  could  result  in  a  net&#xA;saving  of  265M€  per  year  for  the  airlines.  However,  it  would&#xA;generate  286,000  additional  tonnes  of  fuel  burnt  and  901,000&#xA;tonnes  of CO2 emissions at ECAC level per year.&lt;/p&gt;&#xA;&lt;p&gt;This represents about 2,800 round-trips between Paris and New York or&#xA;the annual emissions  of  a  European  city  of  100,000  inhabitants.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(ECAC is the &lt;a href=&quot;https://www.ecac-ceac.org/&quot; rel=&quot;noreferrer&quot;&gt;European conference for civil aviation&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;Hence:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.bbc.com/news/science-environment-50365362&quot; rel=&quot;noreferrer&quot;&gt;British Airways reviews 'fuel-tankering' over climate concerns&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.thomson.co.uk/editorial/press-centre/2007/thomsonfly-reduces-tankering-and-co2-emissions.html&quot; rel=&quot;noreferrer&quot;&gt;Thomsonfly reduces tankering and CO2 emissions&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-04-21T16:48:19.807" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23043" PostTypeId="2" ParentId="23039" CreationDate="2015-11-19T20:37:20.683" Score="30" Body="&lt;p&gt;Since the 1960's and 1970's when political hijackings were a problem, airplanes started to only carry the fuel required for the flight.  This means a typical fuel load will be something on the order of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;taxi fuel at the departure airport&lt;/li&gt;&#xA;&lt;li&gt;fuel to fly and land at the destination at a given altitude and forecast winds&lt;/li&gt;&#xA;&lt;li&gt;if an alternate is needed:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;fuel to fly to the alternate airport&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;45 minutes of reserve fuel&lt;/li&gt;&#xA;&lt;li&gt;perhaps a bit extra for contingency and to keep captains happy (e.g. 5-15 minutes worth of fuel).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For a normal flight this means you'll land with around 45-60 minutes of fuel on board, sometimes less.  You'll fill up for the next leg at this airport while you deplane and enplane passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel at the hub airports is sometimes a bit cheaper due to the fuel contracts the airline can secure when they order massive amounts of fuel every day.  Fuel at outstations that don't see a huge volume of fuel may be quite a bit more expensive.  In this case, and if your weights allow, the airline may elect to load extra fuel that isn't needed.  The purpose of this is so you do not need to buy as much fuel at higher prices at the outstation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I only saw this happen operationally when we were going to be very light and the outstation fuel was very expensive.  Usually our loads were high enough that we were struggling to get all 50 passengers, bags, and especially jumpseaters on board with the required fuel load.  In that case it would not be economical to take more fuel because we'd have to take fewer passengers.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="3504" LastEditDate="2015-11-20T21:00:06.640" LastActivityDate="2015-11-20T21:00:06.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23044" PostTypeId="2" ParentId="23041" CreationDate="2015-11-19T20:49:33.967" Score="5" Body="&lt;p&gt;Here is something off an FAA document about helicopter performance. &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch07.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch07.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Winds&lt;/p&gt;&#xA;&lt;p&gt;Wind direction and velocity also affect hovering, take&#xA;off, and&#xA;climb performance. Translational lift occurs any time there is&#xA;relative airflow over the rotor disk. This occurs whether the&#xA;relative airflow is caused by helicopter movement or by the&#xA;wind. As wind speed increases, translational lift increases,&#xA;resulting in less power required to hover.&#xA;The wind direction is also an important consideration.&#xA;Headwinds are the most desirable as they contribute to the&#xA;greatest increase in performance. Strong crosswinds and&#xA;tailwinds may require the use of more tail rotor thrust to&#xA;maintain directional control. This increased tail rotor thrust&#xA;absorbs power from the engine, which means there is less&#xA;power available to the main rotor for the production of&#xA;lift. Some helicopters even have a critical wind azimuth or&#xA;maximum safe relative wind chart. Operating the helicopter&#xA;beyond these limits could cause loss of tail rotor effectiveness.&#xA;Takeoff and climb performance is greatly affected by wind.&#xA;When taking off into a headwind, effective trans&#xA;lational lift&#xA;is achieved earlier, resulting in more lift and a steeper climb&#xA;angle. When taking off with a tailwind, more distance is&#xA;required to accelerate through transla&#xA;tion lift.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-19T20:49:33.967" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23045" PostTypeId="2" ParentId="23041" CreationDate="2015-11-19T20:51:14.453" Score="9" Body="&lt;p&gt;Moving forward through the air helps to make the helicopter more efficient, and it does not matter if that movement comes from hovering in a headwind or from flying forward. For the same reason, a helicopter will &lt;a href=&quot;https://aviation.stackexchange.com/questions/13397/why-would-a-helicopter-climb-in-a-spiral/13398#13398&quot;&gt;climb faster when flying in a spiral&lt;/a&gt; than when going straight up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technically, flying backwards or sideways will also improve the efficiency of the rotor, but in reverse the helicopter will become directionally unstable. Moving the fuselage sideways will create much more drag, so flying forward is the better choice.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-11-21T22:40:18.473" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23046" PostTypeId="1" CreationDate="2015-11-19T21:07:47.467" Score="0" ViewCount="105" Body="&lt;p&gt;Is there an API or some database somewhere of aircraft that have squawked 7700 (emergency).  Where do mobile apps like FlightRadar24 get their notifications form?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to monitor when flight to/from/diverted to my local airport are involved in emergencies.&lt;/p&gt;&#xA;" OwnerUserId="12349" LastEditorUserId="12349" LastEditDate="2015-11-20T22:27:25.637" LastActivityDate="2015-11-20T22:27:25.637" Title="emergency and/or 7700 squawk database or API?" Tags="&lt;emergency&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2015-11-19T22:00:40.893" ContentLicense="CC BY-SA 3.0" />
  <row Id="23047" PostTypeId="2" ParentId="23037" CreationDate="2015-11-19T21:09:20.567" Score="6" Body="&lt;p&gt;I found a few sources of data that is close but not specifically what you are looking for (Im going to keep looking)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the &lt;a href=&quot;http://www.transtats.bts.gov/fuel.asp&quot; rel=&quot;noreferrer&quot;&gt;total Jet fuel consumption reported by the DOT&lt;/a&gt; (you can filter by airline/carrier)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the &lt;a href=&quot;http://www.eia.gov/state/seds/data.cfm?incfile=/state/seds/sep_fuel/html/fuel_jf.html&quot; rel=&quot;noreferrer&quot;&gt;Jet fuel consumption by state in the USA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an &lt;a href=&quot;https://www.iata.org/policy/Documents/guidance-fuel-storage-may08.pdf&quot; rel=&quot;noreferrer&quot;&gt;interesting report on fuel storage at airports&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Im sure the number vary over time as well as seasonly depending on where in the world you are talking about. On one hand you can argue that the distance/weight comparison of airports may be a useful metric. If we assume planes are least efficient and require the most fuel when flying far and heavy the airport with the greatest departing mass/distance value could shed some light on the number you are looking for (I have no idea how to figure out that number for the record). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind that there is a growing number of planes that are running on Jet A1. A solid chunk of the smaller charter fleet that runs Turbo Props runs on Jet A1 as well as planes like the &lt;a href=&quot;http://www.piper.com/aircraft/m-class/m500/&quot; rel=&quot;noreferrer&quot;&gt;Piper Meridian&lt;/a&gt; and other similar turbo props sneaking their way into the GA market. To round it out diesel GA planes run on Jet-A1 and things like the &lt;a href=&quot;http://www.diamondaircraft.com/aircraft/da42/&quot; rel=&quot;noreferrer&quot;&gt;Diamond-DA42&lt;/a&gt; are making an impact on the GA market and increasing Jet-A1 consumption even if just marginally. That all being said just because a state has a single large or even mega sized airport other states with lots of GA or small charter traffic out of little fields may be able to keep up.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-11-19T22:45:21.040" LastActivityDate="2015-11-19T22:45:21.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23048" PostTypeId="1" AcceptedAnswerId="23051" CreationDate="2015-11-19T21:09:32.600" Score="11" ViewCount="782" Body="&lt;p&gt;If I have a requirement to fly a helicopter in a circle or racetrack over a point of interest that's stationary or moving relatively slowly, is there any reason to prefer left or right turns?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not concerned about visibility and I'm not asking about turns in a landing pattern: I'm asking if - all other things being equal - there's any mechanical, aerodynamic or procedural reason that pilots would prefer to turn in one direction over the other.&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="62" LastEditDate="2015-11-20T15:06:46.930" LastActivityDate="2018-12-12T22:52:18.970" Title="Is there a preferred turn direction for helicopters?" Tags="&lt;helicopter&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23049" PostTypeId="2" ParentId="23048" CreationDate="2015-11-19T21:39:20.417" Score="-3" Body="&lt;p&gt;I have seen turns in both directions. It probably does not matter anyways which way the turn is going, but if it is a single main-rotor helicopter, going with the counter-rotor spin is probably a little more effective at saving fuel although there is not much overall advantage either way if you are not looking for visibility.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-19T21:39:20.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23050" PostTypeId="2" ParentId="23041" CreationDate="2015-11-19T23:40:53.277" Score="10" Body="&lt;p&gt;In general, helicopters require less power while flying forward (or backwards) compared to hover as translational lift (of Effective Translational Lift, ETL) is produced. Even though the blades are providing lift by rotation, the airspeed experienced by the blades is different if wind is present. For example, if there is headwind $v$, the advancing blades will have an airspeed of $r \omega + v$, while the retreating blade will have an airspeed of $r \omega - v$. As lift is proportional to square of airspeed, the implications are obvious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason, it is preferable to take off into the wind, rather than take off vertically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LUXOI.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LUXOI.png&quot; alt=&quot;Power required&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the power required is same for headwind or tailwind. However, tailwind landing (or takeoff) has some disadvantages from stability and power management point of view that is it generally discouraged, like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of landing in tail wind, it is very difficult to abort landing and re-gain forward airspeed. Moving from negative speed to forward speed initially decreases the air speed the main rotor experiences, and the Power Curve shows an initial increase in Power Required. As the helicopter accelerates from negative (ground) speed, the main rotor system loses translational lift before it goes through zero airspeed. As a result, the power required increases, which requires increased pedal application and tail rotor power, precisely when the power requirement is high.&lt;/li&gt;&#xA;&lt;li&gt;If there is a power failure, the chances of safe landing is reduced.&lt;/li&gt;&#xA;&lt;li&gt;There is more risk of running out of directional control. In case there is a tailwind, the helicopter vertical tail (and fuselage) may align try to align with the wind, resulting in uncommanded yaw. If not corrected with proper pedal input, this may lead to loss of control.&lt;/li&gt;&#xA;&lt;li&gt;In case of landing, the possibility of brownout or whiteout conditions is more in case of tailwind. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-22T10:50:13.063" LastActivityDate="2015-11-22T10:50:13.063" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23051" PostTypeId="2" ParentId="23048" CreationDate="2015-11-20T00:54:02.137" Score="11" Body="&lt;p&gt;Most helis make CW turns because the pilots sit on the right and it is easier to judge position and drift when you can look out the window directly.  Turning CCW is no problem however but it takes a tad more concentration.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;one drawback of CW turns from the right seat is that the ALT and ASI would be out of your field of vision, so you'll have some head turning to peek at them. In a CCW turn, its easy to glance at the instruments in the center console.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-11-20T15:01:29.720" LastActivityDate="2015-11-20T15:01:29.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23052" PostTypeId="2" ParentId="23014" CreationDate="2015-11-20T01:07:42.013" Score="1" Body="&lt;p&gt;In the USA, RW aircraft are supposed to avoid the flow of FW traffic and FW traffic have the right of way for landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I would have descended to 500ft instead of climbing. Slight differences in altimeters make 1,200 and 1,000ft too close for comfort. But  500ft AGL (noise abatement be damned in a safety situation) is a perfectly acceptable altitude in a heli. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I would have adjusted my downwind so that I was fairly close to the runway where airplanes are rarely found. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now I have both vertical and horizontal separation, and I am in a continuous position to land, at my convenience. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-11-20T01:07:42.013" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23053" PostTypeId="1" AcceptedAnswerId="23062" CreationDate="2015-11-20T02:07:51.073" Score="7" ViewCount="928" Body="&lt;p&gt;Is there an instrument departure procedure or minimum performance gradient in the absence of a published standard instrument departure (SID)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Departing under instrument flight rules (IFR) in the United States airports sometimes have a SID procedure or alternate take-off minimums which must be observed in order to provide terrain and obstacle clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is no SID or alternate take-off minimum published, is there a standard departure procedure to be used in the absence of other procedures? Is there a climb performance gradient which is assumed that provides clearance under such a departure?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="62" LastEditDate="2015-11-20T14:03:03.407" LastActivityDate="2018-08-10T21:20:27.107" Title="Is there an instrument departure procedure or minimum performance gradient in the absence of a published standard instrument departure?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23054" PostTypeId="1" AcceptedAnswerId="23056" CreationDate="2015-11-20T02:12:15.000" Score="9" ViewCount="12392" Body="&lt;p&gt;The &lt;code&gt;ILS Y or LOC Y RWY 3&lt;/code&gt; approach at Raleigh Exec Jetport at Sanford-Lee County Airport (KTTA) in Sanford, North Carolina features the alternate minimums symbol with an &lt;code&gt;NA&lt;/code&gt; next to it. Normally this symbol means that the airport has non-standard alternate minimums. What does &lt;code&gt;A NA&lt;/code&gt; mean in this case?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/a274CBg.png&quot; alt=&quot;Alternate N/A&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="62" LastEditDate="2015-11-20T14:03:15.170" LastActivityDate="2016-08-30T05:24:20.357" Title="What does Alternate NA mean on an approach plate?" Tags="&lt;instrument-flight-rules&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23055" PostTypeId="1" AcceptedAnswerId="23061" CreationDate="2015-11-20T02:18:48.290" Score="18" ViewCount="32481" Body="&lt;p&gt;There are cases with instrument approaches where there will be multiple approaches to the same runway, in many cases uses some of the same nav aids and positions, but differentiated using alpha characters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example are the &lt;code&gt;ILS Y or LOC Y RWY3&lt;/code&gt; and &lt;code&gt;ILS Z or LOC Z RWY3&lt;/code&gt; approaches at Raleigh Exec Jetport at Sanford-Lee County in Sanford, North Carolina. These approaches both use the &lt;code&gt;LOC/DME I-TTA&lt;/code&gt; there, and some of the same positions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that the differences are subtle in the overall procedure on things like the missed approach procedure and how positions are identified, but I'd love a textbook answer that explains it more thoroughly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9i0qe.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9i0qem.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/83w3Y.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/83w3Ym.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ILS Y and Z (click either image for higher resolution).&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="14897" LastEditDate="2018-06-21T09:56:51.970" LastActivityDate="2018-06-21T10:22:39.597" Title="Why do some approaches have suffix letters such as Y and Z?" Tags="&lt;instrument-flight-rules&gt;&lt;usa&gt;&lt;approach&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23056" PostTypeId="2" ParentId="23054" CreationDate="2015-11-20T02:37:16.100" Score="14" Body="&lt;p&gt;That symbology means this approach cannot be considered when deciding if this airport is a suitable alternate.  This is probably due to the lack of weather reporting or the navaid might not have the required monitoring.  This means the availability of the approach cannot be guaranteed and so you can not rely on it as an alternate.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To file TTA as an alternate you must comply with the the non-standard alternate minimums and you must be legal and equipped to fly either the RNAV (GPS) RWY 03 or RNAV (GPS) RWY 21 procedures.  If the ILS Y RWY 03 is available when you get there, you may fly that procedure instead of the RNAV procedures, you just cannot file it as an alternate on the basis of the ILS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wording in the &lt;a href=&quot;http://aeronav.faa.gov/d-tpp/1512/frntmatter.pdf&quot; rel=&quot;nofollow&quot;&gt;Terminal Procedures legend (PDF)&lt;/a&gt; is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Alternate minimums are Not Authorized due to unmonitored facility or absence of weather reporting service&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="9491" LastEditDate="2016-08-30T05:24:20.357" LastActivityDate="2016-08-30T05:24:20.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23058" PostTypeId="1" AcceptedAnswerId="23109" CreationDate="2015-11-20T06:57:50.083" Score="6" ViewCount="299" Body="&lt;p&gt;As per DO-178 C section 6.2 Overview of Software Verification Activity&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. When it is not possible to verify specific software requirements by exercising the software on a realistic test environment, other means should be provided and their justification for satisfying the software process objectives defined in the Software Verification Plan or Software Verification Results.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After reading this every/most of verification engineers would understand it as other verification methods like Analysis, Inspection etc...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per the discussion and Arguments &quot;The real intent of this objective is how do we verify the software when hardware is unavailable&quot; like, using simulator to verify the software needs to be documented under SVP for this objective satisfaction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is, DO (document Order) as evaluated from version A, B to C now and still have ambiguities and different understandings. Why don't FAA/JAA can come up with examples or layman language explanations for each objective?&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="1696" LastEditDate="2018-04-11T19:37:10.987" LastActivityDate="2018-04-11T19:37:10.987" Title="Why don't DO guidelines have examples?" Tags="&lt;aircraft-certification&gt;&lt;software&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23061" PostTypeId="2" ParentId="23055" CreationDate="2015-11-20T13:34:03.393" Score="12" Body="&lt;p&gt;The naming convention is explained in &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/chapter_4.pdf&quot; rel=&quot;noreferrer&quot;&gt;Chapter 4 of the FAA's Instrument Procedures Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When two or more straight-in approaches with the same  type of&#xA;  guidance exist for a runway, a letter suffix is added  to the title of&#xA;  the approach so that it can be more easily  identified. These approach&#xA;  charts start with the letter Z  and continue in reverse alphabetical&#xA;  order.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.3B_Chgs_1-26_rev.pdf&quot; rel=&quot;noreferrer&quot;&gt;TERPS&lt;/a&gt; explanation (section 161) is a little more specific:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;d. Duplicate identification suffix.&lt;/strong&gt; When more than one procedure to the same runway uses the same type of navigation system for lateral&#xA;  guidance within the final approach segment, differentiate each&#xA;  procedure by adding a non-repeating alphabetical suffix using the&#xA;  letters “S” through “Z.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Handbook gives the example of two approaches at Chicago Midway (KMDW), which has the &lt;a href=&quot;http://155.178.201.160/d-tpp/1512/00081RZ13C.PDF&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) Z RWY 13C&lt;/a&gt; and &lt;a href=&quot;http://155.178.201.160/d-tpp/1512/00081RRY13C.PDF&quot; rel=&quot;noreferrer&quot;&gt;RNAV (RNP) Y RWY 13C&lt;/a&gt; approaches. They're both straight-in GPS approaches to the same runway, but one requires &lt;a href=&quot;https://en.wikipedia.org/wiki/Required_navigation_performance&quot; rel=&quot;noreferrer&quot;&gt;RNP&lt;/a&gt; and the other doesn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the question itself and &lt;a href=&quot;https://aviation.stackexchange.com/questions/23055/why-are-there-sometimes-multiple-approaches-to-the-same-runway-differentiated-by/23061#comment53436_23061&quot;&gt;this comment&lt;/a&gt; note, there are plenty of other possible differences between approaches to the same runway; RNP is just one example. Having multiple approaches allows an airport to accommodate aircraft with different equipment and capabilities or, as section 140 of the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.3B_Chgs_1-26_rev.pdf&quot; rel=&quot;noreferrer&quot;&gt;TERPS&lt;/a&gt; puts it, to &quot;gain an operational advantage&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To permit use by aircraft with limited navigational equipment, an IFP [Instrument Flight Procedure]&#xA;  should be formulated using a single navigation source whenever&#xA;  possible. The use of multiple navigation sources of the same or&#xA;  different types may be permitted to gain an operational advantage&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have no idea how to find out why a specific runway has multiple approaches or how the approaches were designed; presumably it's something that the FAA and the airport operator (and maybe even the airlines) work out based on local runway use and traffic requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the example in the question, one plate requires GPS, the other DME or radar. So a non-GPS equipped aircraft can still use the ILS, but with different ways of getting to it, different minima, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that there's a similar naming convention for circling approaches:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Approaches that do not have straight-in landing minimums  are&#xA;  identified by the type of approach followed by a letter.  [...] As can&#xA;  be seen from the example, the first approach of  this type created at&#xA;  the airport is labeled with the letter A,  and the lettering continues&#xA;  in alphabetical order.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Their example is &lt;a href=&quot;http://www.airnav.com/airport/KMFR&quot; rel=&quot;noreferrer&quot;&gt;Rogue Valley International - Medford (KMFR)&lt;/a&gt;, which has the following circling approaches:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;VOR-A&lt;/li&gt;&#xA;&lt;li&gt;LOC/DME BC-B&lt;/li&gt;&#xA;&lt;li&gt;VOR/DME-C&lt;/li&gt;&#xA;&lt;li&gt;RNAV (GPS)-D&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's no explanation that I could find in the Handbook or TERPS to explain why circling approaches must have a letter even if the navigation systems are different. But as @RalphJ mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/questions/23055/why-are-there-sometimes-multiple-approaches-to-the-same-runway-differentiated-by/23061#comment53588_23061&quot;&gt;a comment&lt;/a&gt;, this provides a clear way to identify multiple circling approaches using the same guidance, e.g. a VOR-A approach from the north and a VOR-B one from the south.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="14897" LastEditDate="2018-06-21T10:22:39.597" LastActivityDate="2018-06-21T10:22:39.597" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23062" PostTypeId="2" ParentId="23053" CreationDate="2015-11-20T13:54:19.380" Score="5" Body="&lt;p&gt;Yes, the required obstacle clearance is based on this minimum performance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cross the departure end of the runway (DER) at at least 35ft AGL (that's above the DER, not above the airport reference elevation)&lt;/li&gt;&#xA;&lt;li&gt;Climb to 400ft above the DER before turning&lt;/li&gt;&#xA;&lt;li&gt;Maintain a climb of at least 200ft per nautical mile (FPNM) until reaching minimum IFR altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The minimum IFR altitude is 1000ft above obstacles, or 2000ft in mountainous areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is explained in detail in &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/FAA-H-8083-16B_Chapter_1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chapter 1 of the FAA Instrument Procedures Handbook&lt;/a&gt; (starting on page 1-14). The FAA carries out an assessment to see if the airport needs a specific procedure (ODP or SID) and if it doesn't then the standard clearance performance above applies:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If an aircraft may  turn in any direction from a runway within the&#xA;  limits of the  assessment area and remain clear of obstacles that&#xA;  runway  passes what is called a diverse departure assessment, and  no&#xA;  ODP is published.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2018-08-10T21:20:27.107" LastActivityDate="2018-08-10T21:20:27.107" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23063" PostTypeId="1" AcceptedAnswerId="23065" CreationDate="2015-11-20T14:21:02.017" Score="9" ViewCount="4690" Body="&lt;p&gt;A minority of the world, specifically Russia and China, uses the metric system in aviation. ATC will tell the pilots to &quot;climb to 900 meters height&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do pilots of international flights manage this? Do they request the ATC to provide altitude in feet, or do they perform the conversion manually and dial in the altitude in feet to the autopilot?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1696" LastEditDate="2015-11-20T15:57:30.403" LastActivityDate="2015-11-20T16:18:35.957" Title="How do pilots manage metric altitude?" Tags="&lt;air-traffic-control&gt;&lt;international&gt;&lt;units&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23064" PostTypeId="2" ParentId="23063" CreationDate="2015-11-20T14:33:07.940" Score="-3" Body="&lt;p&gt;Here is a page with all the info on this subject: &lt;a href=&quot;http://aerosavvy.com/metric-imperial/&quot; rel=&quot;nofollow&quot;&gt;http://aerosavvy.com/metric-imperial/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Altimeter Calibration: mb, hPa &amp;amp; inHg&#xA;  Altimeters can be set using hPa or inHg.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Altimeters can be set using hPa (mb) or inHg.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In order to calibrate our altimeters for varying atmospheric pressure, we set the current pressure reported by ground stations. Pressure is reported in inches of mercury (inHg), hectopascals (hPa), or millibars (mb). North America and Japan use the inches of mercury measurement. Hectopascals dominate the rest of the aviation world (millibars and hectopascals are equal). For years, altimeter manufactures have provided two calibration windows for hPa and inHg. This makes setting our altimeters easy no matter where we fly.  Just dial the reported pressure into one of the windows and you’re all set! Newer, digital altimeters have a button to switch between units. I like the older ones, they’re easier to set.&#xA;  Measuring Altitude: Feet vs. Meters&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Here’s where things get tricky. Because of the proliferation of American and British aircraft during the early years of aviation, the imperial foot became standard for altitude measurement. China (PRC), North Korea, and Russia, however, use meters for altitude measurement.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As luck would have it, I often fly over Chinese, Russian, and North Korean airspace. The altimeters in our older aircraft, like the 767, are calibrated in feet. When flying into metric airspace, we use a conversion card. When Shanghai Control clears us to descend to 3600 meters, we check the card and descend to the equivalent: 11,800 feet. Does this sound like a pain in the you-know-where? It is!&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;During rush hour at airports like Shanghai and Beijing, the controllers rattle off clearances very fast. They will often assign us a heading, speed and metric altitude all in one shot. Doing the metric altitude conversion adds an additional task to an already challenging environment. We stay on our toes in metric airspace! The good news is that newer generation airplanes have a switch that can change the aircraft’s native altimetry display from imperial to metric units. When crossing into metric airspace, the crew hits the switch and the airplane understands the metric system. This reduces crew workload considerably.&#xA;  Distance Across The Ground&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;World-wide, the nautical mile (nm) is the standard for measuring the distance an aircraft travels across the ground. That’s nice and easy and it makes me happy. :)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Other lateral measurements are a mess. Most of the world measures runway length in meters while North America uses feet. Most of the world measures airport visibility in meters. North America? Not nautical miles, not meters, but statute miles! Huh?? Not to worry, North America changes back to feet when measuring Runway Visual Range (runway visibility measured with a laser), while the rest of the world sticks with meters. Confused? I sure am, and I do this for a living!&#xA;  Wind speed: Knots vs. Meters/Second&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When reporting weather, airports in China and Russia state the surface winds in meters per second (m/s). They love this metric stuff! The rest of the world reports wind in knots (nautical miles / hour). Converting is easy:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1 m/s ≈ 2 kts&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Double the m/s and we are close to knots. If Shanghai tower tells me the winds are 7 meters per second, I know they are blowing just a little shy of 14 knots. I can land in that much wind. Any more than that and I’ll let my first officer do it!&#xA;  Is flying safe with all these different units?&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Yes!  Pilots flying international routes deal with this assortment of units daily. We can juggle them in our sleep. While it’s certainly an added challenge, it’s an important part of our occupation. There are very well defined standards and procedures that pilots use to work with the different units. Flying continues to be the safest form of transportation available.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Basically, it is that either the pilots have tables to convert units or the instruments can show both types. In either case, it would be very easy to follow the ATC instructions.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-11-20T16:18:35.957" LastActivityDate="2015-11-20T16:18:35.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23065" PostTypeId="2" ParentId="23063" CreationDate="2015-11-20T14:33:16.440" Score="10" Body="&lt;p&gt;In areas where the ATC provides the altitude in meter (China (PRC), North Korea, and Russia), depending on the equipment (altimeter), the pilot can determine what to do:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of older aircraft, where the altimeter is calibrated in feet, the pilots use a conversion card for determining the altitude in feet, before dialing in the altitude to the autopilot.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EJ53k.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EJ53k.jpg&quot; alt=&quot;Conversion Card&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: aerosavvy.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The conversion charts are standardized for the airspace and the pilots have to use it. For Chinese airspace refer &lt;a href=&quot;https://www.faa.gov/air_traffic/separation_standards/rvsm/documents/Pilot_Opr_Guidance_Mtrl_China_RVSM_2007101014251255.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA document on Chinese RVSM&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of modern aircraft displays, the altimeter can be made to display altitude in imperial (feet) or metric (meter) units.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-20T14:33:16.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23066" PostTypeId="2" ParentId="23037" CreationDate="2015-11-20T18:28:13.040" Score="8" Body="&lt;p&gt;The best data I could find is in &lt;a href=&quot;http://www.nrel.gov/docs/fy14osti/60254.pdf&quot;&gt;this paper about biofuels&lt;/a&gt;, which has data for US airports in 2014. Based on my reading of the chart on page 14 and some conversion:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Airport  Millions of barrels per year&#xA;KLAX     48.6&#xA;KJFK     43.5&#xA;KATL     30.8&#xA;KORD     30.5&#xA;KSFO     28.3&#xA;KMIA     26.0&#xA;KDFW     25.4&#xA;PANC     19.0&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Comparing this to the &lt;a href=&quot;http://www.bga-aeroweb.com/Top-100-US-Airports-2013.html&quot;&gt;top US airports in 2013&lt;/a&gt;, it is interesting to note that LAX and JFK use significantly more fuel than KATL, despite passenger traffic figures ranked the other way. Also notable is Anchorage showing up here right after DFW, while MIA and ANC are the only ones not in the top 10 by passengers, showing up at 11th and 58th, respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figures for other countries have been harder to find. &lt;a href=&quot;http://www.wam.ae/en/news/emirates/1395226435335.html&quot;&gt;This article from 2004&lt;/a&gt; estimates the &lt;strong&gt;Dubai International&lt;/strong&gt; usage at &lt;strong&gt;24.2 million barrels&lt;/strong&gt; that year, which has certainly grown since then. &lt;a href=&quot;http://content.emirates.com/downloads/ek/pdfs/environment/environment_report_2012_13_locked.pdf&quot;&gt;The 2012-2013 environmental report from Emirates Group&lt;/a&gt; lists their consumption at 73.9 million barrels, and half of this figure would be in line with the other numbers available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a &lt;a href=&quot;http://www.ft.com/intl/cms/s/a3ab9d54-9cff-11da-8762-0000779e2340,Authorised=false.html?siteedition=intl&amp;amp;_i_location=http%3A%2F%2Fwww.ft.com%2Fcms%2Fs%2F0%2Fa3ab9d54-9cff-11da-8762-0000779e2340.html%3Fsiteedition%3Dintl&amp;amp;_i_referer=&amp;amp;classification=conditional_standard&quot;&gt;similar figure for &lt;strong&gt;Heathrow&lt;/strong&gt;&lt;/a&gt;, listing it at 20-25 million liters per day, depending on season, which gives a range of &lt;strong&gt;61.2 to 76.5 million barrels&lt;/strong&gt; per year, well ahead of the US airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Becoming even fuzzier, the pipeline to &lt;strong&gt;Narita Airport&lt;/strong&gt; in Tokyo transported &lt;a href=&quot;https://en.wikipedia.org/wiki/Narita_International_Airport&quot;&gt;130 billion liters in its first 30 years of operation&lt;/a&gt;, which averages out to &lt;strong&gt;36.3 million barrels&lt;/strong&gt; per year.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-11-20T18:28:13.040" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23068" PostTypeId="1" CreationDate="2015-11-20T22:26:46.000" Score="13" ViewCount="14766" Body="&lt;p&gt;Is it possible for one single person to fly, maneuver and land an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;noreferrer&quot;&gt;Airbus A380&lt;/a&gt; by him/herself?&lt;/p&gt;&#xA;" OwnerUserId="12361" LastEditorUserId="3386" LastEditDate="2015-11-21T13:21:53.353" LastActivityDate="2017-10-18T17:18:07.807" Title="How many pilots are required in an Airbus A380?" Tags="&lt;landing&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23069" PostTypeId="2" ParentId="23068" CreationDate="2015-11-20T22:31:35.243" Score="17" Body="&lt;p&gt;In general, it is perfectly &lt;em&gt;possible&lt;/em&gt; for a single person to fly modern aircraft like A380. However, regulations require the presence of 2 pilots (PF and PNF). In other words, technically yes, legally no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In long distance flights, the aircraft usually carries two sets of cockpit crew (4, each capable of flying the aircraft) as the flight hours may be more than the permitted flying hours.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22690&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Advisory Circular 25.1523-1&lt;/a&gt; deals with the minimum flight crew in transport category aircraft. According to Section 5 Certification Procedures, Subsection c, Testing (vi) Incapacitated Crew member,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Whenever the applicable operating rule requires a minimum flightcrew of at least two pilots, the certification program should include a demonstration&#xA;  of operations during the total incapacitation of a crewmember at any point in a given flight. It must be shown that the airplane can be operated safely and landed safely with the remaining crew at a planned or unplanned destination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="14957" LastEditDate="2017-10-18T17:18:07.807" LastActivityDate="2017-10-18T17:18:07.807" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23070" PostTypeId="2" ParentId="28" CreationDate="2015-11-20T22:43:03.397" Score="5" Body="&lt;p&gt;I am a CFI CFII MEI with over 8000 hours dual given and direct experience in this area of confusion.  Just to clarify everything above into what is and isn't.  It comes down to they type of instructor you received your sport pilot training from. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they are the traditional CFI your minimum of 20 hours of dual that you did with them counts.  If they were a Light Sport rated CFI none of your dual will count.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another big concern is if you do your private pilot training part 61 or 141.  Part 61 would be the least expensive way to go since you get credit for your 20 (+) hours of dual you flew with a normal CFI.  However, under Part 141 you are signing up for an FAA approved curriculum and you have to fly the whole program and NO PREVIOUS training regardless of type of instructor can be carried over.  This is consistent with any type of 141 program regardless if it is IFR, Commercial, Multi, etc., now previous experience logged can be counted towards a Part 141 program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The honest truth about 141 being a savings only really applies when you start from one rating and go right to the next, any time spent flying above the minimums from the previous rating or  between ratings can be applied to the next.  However there are now 141 programs out there that let you work on a combined certification where you are working on your private and IFR at the same time, this has the potential to be a real money saver for the career focused student, or even someone who is not career bound but is committed to having an Instrument rating for safety or more reliable travel.&lt;/p&gt;&#xA;" OwnerUserId="12363" LastEditorUserId="12116" LastEditDate="2017-09-12T09:26:30.507" LastActivityDate="2017-09-12T09:26:30.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23073" PostTypeId="2" ParentId="23068" CreationDate="2015-11-21T08:23:09.763" Score="3" Body="&lt;p&gt;Of course it is perfectly legal to fly an A380 with one pilot. You need to observe a few details, however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an explanation let me first say something about certification. When you compress all legal barriers to flight into one fact, it comes down to&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Harm actively involved persons (like pilots) in less than one case per 100,000 (10$^5$) flight hours,&lt;/li&gt;&#xA;&lt;li&gt;Harm passively involved persons (like passengers) in less than one case per 10,000,000 (10$^7$) flight hours, and&lt;/li&gt;&#xA;&lt;li&gt;Harm not involved persons (like people on the ground) in less than one case per 1,000,000,000 (10$^9$) flight hours.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now you can see where this is heading: If you don't take passengers onboard and fly the A380 as your recreational jet, you can do this with a private pilot license and all by yourself. All you need is a medical, the license and a type rating on the aircraft. And the aircraft must be airworthy, of course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, however, you carry others with you, you need to be 100 times more safe. This is accomplished by taking a spare pilot with you. In general, the second pilot shares the burden of flying, navigating and communicating with the first, but the aircraft has been designed to be flown by one pilot. Otherwise the second pilot would increase the risk of something going wrong - with two pilots you have twice the risk of one falling ill during the flight. Certification makes sure that one pilot by himself can fly and land the aircraft in an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older designs needed as many as five people to fly the aircraft (first pilot, co-pilot, flight engineer, navigator, radio operator), and in some not all controls could be reached from the pilot's seat. Steering those was more like sailing a ship: The pilot would command a thrust setting, and the flight engineer had to adjust the throttles (and mixture, cowl flaps, fuel valves ...). On the A380, however, all essential controls can be operated from either seat, and in total a crew of two is sufficient to comply with all regulations, including those for commercial operation.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-21T09:04:30.627" LastActivityDate="2015-11-21T09:04:30.627" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="23074" PostTypeId="1" CreationDate="2015-11-21T13:45:27.840" Score="8" ViewCount="1024" Body="&lt;p&gt;I am curious to know, from current airline pilots, if the formatting - and therefore reliability and ease of use - of pre-departure clearances (PDC's) has improved since they were first introduced?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back then we would see &lt;a href=&quot;http://asrs.arc.nasa.gov/publications/directline/dl5_pdc.htm&quot;&gt;differing formats, incorrect flight numbers and routings&lt;/a&gt;, and the like.  ATC would send them to the company and then the company would give them to the flight crew together with other relevant documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure that the process has greatly improved since those days, but I'd like to know if PDCs have now been standardized?&lt;/p&gt;&#xA;" OwnerUserId="12364" LastEditorUserId="62" LastEditDate="2016-01-21T13:21:44.543" LastActivityDate="2016-04-23T20:46:12.567" Title="Is there a standard format for pre-departure clearances?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;pre-clearance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23075" PostTypeId="2" ParentId="23024" CreationDate="2015-11-21T14:01:03.757" Score="1" Body="&lt;p&gt;The point is to be sure that the affected engine is shut down. Boeing has inserted a recommendation for that in their Flight Crew Training Manual (FCTM), mentioning explicitly:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mistakes were done in the past.&lt;/li&gt;&#xA;&lt;li&gt;Don't hurry in the engine shutdown.&lt;/li&gt;&#xA;&lt;li&gt;PF must coordinate with the PM in the procedure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The procedure also includes to retard thrust on the affected engine &lt;em&gt;slowly&lt;/em&gt;. It gives time to feel something unexpected, like the aircraft loosing power on both engines (for a twin).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find such recommendation in the Boeing 737 NG FCTM and the 777 FCTM, like &lt;a href=&quot;http://www.piac.com.pk/trainingsection/pdffiles/777/b777-fctm_22072010.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;, page 308 (this is logical page 8-8 in both manuals). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Recommended technique for in-flight engine shutdown&lt;/em&gt;&lt;/strong&gt;&lt;br&gt;&#xA;Extract for convenience:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BpOA3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BpOA3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;These FCTM are usually customized by operators / airlines before being used for crew training, so the recommendation may be improved or edited to better fit the company standards, but that's the idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The recommendation is not to be confused with the checklist for shutting down an engine, which depends on the cause of the problem. The checklists are part of the non-normal checklists (referenced in the extract above as &lt;em&gt;NNC&lt;/em&gt;). E.g. if there is a fire detected, the crew will apply the related NNC which is found in the Quick Reference Handbook (QRH), like &lt;a href=&quot;http://www.737ng.co.uk/B777%20QRH%20Quick%20reference%20Handbook.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one&lt;/a&gt;, page 170. Extract for convenience:&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DJu98.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DJu98.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;While the NNC in the QRH just provides steps like:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Thrust lever (affected side) . . . . . .  Confirm. . . . . . . . . .  Idle&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;the FCTM recommendation provides a way to train crews to ensure the &lt;em&gt;affected side&lt;/em&gt; is properly identified.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-11-21T15:31:12.870" LastActivityDate="2015-11-21T15:31:12.870" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23076" PostTypeId="2" ParentId="7934" CreationDate="2015-11-21T14:04:53.900" Score="6" Body="&lt;p&gt;This question is incomplete without a mention of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Traigh_Mh%C3%B2r&quot; rel=&quot;noreferrer&quot;&gt;Traigh Mhor airport&lt;/a&gt; on Barra, which shows that for the right aircraft, on the right sort of beach, at the right state of tide, the probability of a successful landing is good enough to sustain a commercial service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J94jy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J94jy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And previously from a major airline... (though operated by Loganair in both cases)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/osAHv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/osAHv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were some doubts about the sustainability of this service as the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter&quot; rel=&quot;noreferrer&quot;&gt;Twin Otters&lt;/a&gt; approached retirement age, but they are now back in production, probably thanks to this and similar niche roles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://news.bbc.co.uk/local/highlandsandislands/hi/people_and_places/nature/newsid_9096000/9096042.stm&quot; rel=&quot;noreferrer&quot;&gt;(Picture source)&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.alamy.com/stock-photo-cockle-strand-traigh-mhor-beach-airstrip-loganair-british-airways-13997728.html&quot; rel=&quot;noreferrer&quot;&gt;Second picture source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4068" LastEditorUserId="4068" LastEditDate="2015-11-21T14:17:33.813" LastActivityDate="2015-11-21T14:17:33.813" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23079" PostTypeId="1" CreationDate="2015-11-21T17:58:25.337" Score="5" ViewCount="580" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QB1pS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QB1pS.png&quot; alt=&quot;screen capture - details of original image unknown&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Screen capture on iMac, of photo posted and claimed taken 11/21/15.&#xA;Palm Springs, CA&lt;/p&gt;&#xA;" OwnerUserId="12369" LastActivityDate="2015-11-21T19:05:51.170" Title="What are these aircraft? Seen in silhouette over Palm Springs" Tags="&lt;propeller&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23080" PostTypeId="2" ParentId="23079" CreationDate="2015-11-21T18:20:32.633" Score="5" Body="&lt;p&gt;Looks like two Douglas DC-3, the one on the right being the military version known as the C-47 &quot;Skytrain&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/5/57/Douglas_c47-a_skytrain_n1944a_cotswoldairshow_2010_arp.jpg&quot; alt=&quot;pic&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_C-47_Skytrain#/media/File:Douglas_c47-a_skytrain_n1944a_cotswoldairshow_2010_arp.jpg&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;: Adrian Pingstone&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="1961" LastEditDate="2015-11-21T19:05:51.170" LastActivityDate="2015-11-21T19:05:51.170" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23081" PostTypeId="1" CreationDate="2015-11-21T18:32:50.447" Score="2" ViewCount="3355" Body="&lt;p&gt;Could someone explain what the blue zipper line 'Atlantic Low Control Area' is in the images below?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What type of airspace is this? How far off the coast does it start? Would it still be G to 1200 and E to 18000 in this area? Is this related to a Warning area which begins 12 NM off the coast? Why are there two parallel lines? I'm not really sure what questions to ask about it but I want to understand it well enough to be able to explain it in a check ride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1vb4T.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1vb4T.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TZn9i.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TZn9i.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2018-05-25T14:29:37.217" Title="What type of airspace is an Atlantic Low Control Area?" Tags="&lt;airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23082" PostTypeId="1" AcceptedAnswerId="23085" CreationDate="2015-11-21T18:48:55.290" Score="6" ViewCount="968" Body="&lt;p&gt;I understand the long form:&#xA;&quot;Remarks: runway 7 Automated Terminal Information Service (ATIS) G landline&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what I don't understand is what runway 7 has to do with the ATIS information (this particular airport has one runway, RWY 7-25). What does the 'G' mean? What does the 'landline' mean? &lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-11-21T19:36:08.767" Title="What does this METAR remark mean? 'RMK RWY 7 ATIS G LL'" Tags="&lt;metar&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23083" PostTypeId="2" ParentId="23081" CreationDate="2015-11-21T18:49:47.327" Score="2" Body="&lt;p&gt;About the jagged lines from &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Class E Airspace exists at 1200' AGL unless designated otherwise. The lateral and vertical limits of all Class E, (up to, but not including 18,000') are shown by narrow bands of vignette on Sectionals and TACs.&lt;/p&gt;&#xA;&lt;p&gt;Controlled airspace floors of 700' above the ground are defined by a magenta vignette; floors other than 700' that laterally abut uncontrolled airspace (Class G) are defined by a blue vignette; differing floors greater than 700' above the ground are annotated by a symbol and a number indicating the floor.&lt;a href=&quot;https://i.stack.imgur.com/nM85Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nM85Z.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;If the ceiling is less than 18,000' MSL, the value (preceded by the word &amp;quot;ceiling&amp;quot;) is shown along the limits of the controlled airspace. These limits are shown with the same symbol indicated above.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A little more search say that it is the floor altitude of that control area. The parallel lines are when the floor altitude changes (from 1300 MSL to 2700MSL and 1700MSL to 5500MSL).&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-21T18:49:47.327" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23085" PostTypeId="2" ParentId="23082" CreationDate="2015-11-21T19:36:08.767" Score="11" Body="&lt;p&gt;I have a suspicion that you're looking at KLZU's METAR. Basically, they're inputting their manually written METAR into the system, and when they send it out they're adding the Runway in Use(RWY 7) and ATIS code(ATIS G) to their METAR, which they're really not supposed to do. I suspect that LL is the person who recorded it's operating initials at the facility, also not supposed to be transmitted as a part of the METAR.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2015-11-21T19:36:08.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23088" PostTypeId="2" ParentId="23041" CreationDate="2015-11-21T22:00:12.373" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Translational_lift&quot; rel=&quot;nofollow&quot;&gt;Effective Translational Lift&lt;/a&gt; (ETL) is lift generated by airflow over the rotor, and increases the effectiveness of the airfoil by about 15%.  ETL is generated beginning about 15knots of airflow over the rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the helicopter is landing with the nose pointed into the wind, a headwind decreases the ground speed at which ETL is generated. So a helicopter landing into a 15 knot wind can maintain ETL all the way into a hover (when groundspeed is zero).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintaining ETL as long as possible into the landing is important for 2 different reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;it requires less power to fly the approach, increasing the safety factor in the case of a go-around, or in high density altitude or high gross weight landings, the requirement to make a &lt;a href=&quot;http://www.copters.com/pilot/run_landing.html&quot; rel=&quot;nofollow&quot;&gt;run-on landing&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;by maintaining ETL, there is no chance of entering &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_ring_state&quot; rel=&quot;nofollow&quot;&gt;ring vortex state&lt;/a&gt;, which is nearly unrecoverable close to the ground, especially in steep approaches&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-11-22T14:35:42.670" LastActivityDate="2015-11-22T14:35:42.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23090" PostTypeId="2" ParentId="16800" CreationDate="2015-11-21T22:30:08.387" Score="4" Body="&lt;p&gt;Unlike in a RC or a maple tree seed, recovering from zero-RPM rotor is not possible in a helicopter because the &quot;driving region&quot; of the rotor system can't produce enough rotation to generate lift in the &quot;driven region.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, once a heli rotor RPM is reduced below about 80%, it stops flying&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-11-21T22:30:08.387" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23091" PostTypeId="1" AcceptedAnswerId="23101" CreationDate="2015-11-21T22:43:03.243" Score="5" ViewCount="3385" Body="&lt;p&gt;When hovering, how does a pilot deal with wind direction? As when &lt;a href=&quot;https://aviation.stackexchange.com/q/23041/8730&quot;&gt;landing&lt;/a&gt; is it preferable to point the nose into the wind? Is this a primary consideration for the pilot considering that he may need to maintain visibility on something, such as during a rescue or a news operation? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And is wind direction more of a factor when hovering in or out of ground effect?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-11-22T16:25:11.897" Title="Is there a preferred wind direction for a helicopter in hover?" Tags="&lt;helicopter&gt;&lt;wind&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23092" PostTypeId="2" ParentId="23091" CreationDate="2015-11-22T00:27:34.360" Score="-2" Body="&lt;p&gt;The best situation when hovering is for there to be little or no wind. There is no &quot;preferred&quot; way for the wind to blow relative to the helicopter unless there is a certain place you want to see. However, because of their designs, helicopters will tend to &quot;weather-cock&quot; in the direction the wind is coming from due to the CP-CG relationship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found this FAA doc on helicopter handling with a bit more stuff: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch09.pdf&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch09.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-11-22T01:08:46.957" LastActivityDate="2015-11-22T01:08:46.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23093" PostTypeId="2" ParentId="23081" CreationDate="2015-11-22T00:38:30.607" Score="3" Body="&lt;p&gt;The Atlantic Low Control Area is a Class E area in international airspace, where domestic ATC procedures may be used for separation procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the relevant excerpts from &lt;a href=&quot;http://tfmlearning.fly.faa.gov/publications/atpubs/AIR/air1901.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Chapter 19. Other Airspace Areas&#xA;Section 1. General&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Offshore/Control Airspace Areas are locations designated in international airspace (between the U.S. 12-mile territorial limit and the CTA/FIR boundary, and within areas of domestic radio navigational signal or ATC radar coverage) wherein domestic ATC procedures may be used for separation purposes. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class A Offshore/Control Airspace Areas are identified as “High&quot; (e.g., Atlantic High; Control 1154H). Class E areas are identified as “Low&quot; (e.g., Gulf of Mexico Low, Control 1141L)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The two parallel lines differentiate floors of class E airspace that is neither 700 feet nor 1200 feet AGL (Above Ground Level).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="26946" LastEditDate="2018-05-25T14:29:37.217" LastActivityDate="2018-05-25T14:29:37.217" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23094" PostTypeId="1" AcceptedAnswerId="23095" CreationDate="2015-11-22T03:16:16.940" Score="3" ViewCount="850" Body="&lt;p&gt;Has there ever been a commercial airliner that the seats have been facing rearwards? It sounds like rear-facing seats would be significantly safer. In addition, the procedure for rear-facing bracing (&lt;a href=&quot;https://en.wikipedia.org/wiki/Brace_position&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Brace_position&lt;/a&gt;), seems significantly simpler and more obvious than traditional methods. &lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2015-11-22T03:40:04.177" Title="Has there ever been an commercial airplane with rear-facing seats?" Tags="&lt;safety&gt;&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-11-22T21:36:00.557" ContentLicense="CC BY-SA 3.0" />
  <row Id="23095" PostTypeId="2" ParentId="23094" CreationDate="2015-11-22T03:30:18.330" Score="4" Body="&lt;p&gt;Some airlines do offer rear facing seats in business/first class. However, this is more to save space than for increasing safety. For example, British Airways offers a mix of forward and backward facing seats in its business class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iFpMb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iFpMb.jpg&quot; alt=&quot;BA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Forbes.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BAC &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Siddeley_Trident&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawker Siddeley Trident&lt;/a&gt; offered rear-facing seats while it was in service. (Note the visible cockpit). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/goFVp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/goFVp.jpg&quot; alt=&quot;Trident&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Armed forces of a number of countries use rear facing seats, like the RAF and USN in their C-2 Greyhounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uHBKK.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uHBKK.jpg&quot; alt=&quot;C2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:C-2A_interior_DN-SD-03-16988.JPEG#/media/File:C-2A_interior_DN-SD-03-16988.JPEG&quot; rel=&quot;nofollow noreferrer&quot;&gt;C-2A interior DN-SD-03-16988&lt;/a&gt;&quot; by Camera Operator: PH1(AW) Shawn P. Eklund, USN - US Defense Visual Information Center photo DN-SD-03-16988. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-22T03:40:04.177" LastActivityDate="2015-11-22T03:40:04.177" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23096" PostTypeId="1" AcceptedAnswerId="23104" CreationDate="2015-11-22T04:14:47.893" Score="51" ViewCount="7047" Body="&lt;p&gt;I was intrigued knowing from this SE-Aviation post that modern, aircraft Emergency Evacuation-Slide inflation-cylinders are often filled with a CO2+N2 mixture. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See  here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12627/which-gas-is-used-to-fill-the-evacuation-slides-of-modern-aircraft&quot;&gt;Which gas is used to fill the evacuation slides of modern aircraft?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Intuitively the reason behind the CO2 addition instead of using simply pure N2 is not very obvious to me. Digging deeper into the technology, Wikipedia reveals that &lt;em&gt;&quot;The CO2 is used to slow down the rate at which the valve expends the gases.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea about the science behind this? Why would CO2 slow down the inflation rate? And why do we want to slow the inflation in the first place? Fabric damage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what is the CO2 percent in the mix, anyone know?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="14897" LastEditDate="2020-01-25T06:40:47.787" LastActivityDate="2020-01-25T06:40:47.787" Title="Aircraft Emergency Evacuation slide inflation system: Why is a mixture of CO2 &amp; N2 used instead of pure N2?" Tags="&lt;emergency-slide&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23097" PostTypeId="1" AcceptedAnswerId="23197" CreationDate="2015-11-22T04:22:52.367" Score="3" ViewCount="3094" Body="&lt;p&gt;For terrorism concerns I think many airlines offload checked in baggage if a passenger somehow does not end up travelling on a flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How strictly are these rules followed? e.g. If a connecting passenger with a tight connection cannot make it to the gate in time will the airline actually send in a ramp guy into the baggage hold to remove specific pieces of baggage? How feasible is it to do thing when the bags are in pods or the Unit Load Devices? Do they have to remove the load device from the hold before they can extract a specific bag?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the gate delay of just waiting for the errant, late passenger compare to the time &amp;amp; effort needed to find &amp;amp; offload his bags? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. Since bags do get misrouted I'm sure at least &lt;em&gt;some&lt;/em&gt; bags fly without a passenger owning them on board. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-11-01T11:39:49.473" LastActivityDate="2016-11-21T08:05:46.700" Title="Is baggage always offloaded when a passenger does not travel?" Tags="&lt;airport&gt;&lt;passenger&gt;&lt;terrorism&gt;&lt;baggage-handling-system&gt;" AnswerCount="1" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="23098" PostTypeId="2" ParentId="23096" CreationDate="2015-11-22T04:55:27.793" Score="31" Body="&lt;p&gt;The &lt;span class=&quot;math-container&quot;&gt;$\text{CO}_{2}$&lt;/span&gt; is used as a diluent.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The pressure vessels (for inflating the slides) usually have nitrous oxide (or similar) compounds, that undergo exothermal thermal decomposition during inflation. For example, &lt;span class=&quot;math-container&quot;&gt;$\text{NO}$&lt;/span&gt; reaches temperatures of &lt;span class=&quot;math-container&quot;&gt;$\sim 650\,^{\circ}\text{C}$&lt;/span&gt; during thermal decomposition. As &lt;span class=&quot;math-container&quot;&gt;$\text{CO}_{2}$&lt;/span&gt; absorbs heat during its expansion, this prevents any damage to the fabric.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For the same reason, the presence of &lt;span class=&quot;math-container&quot;&gt;$\text{CO}_{2}$&lt;/span&gt; controls the reaction rate of the decomposition of the nitrous oxide as it is usually impossible to prevent decomposition from generating unpredictable amounts of gas.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The &lt;span class=&quot;math-container&quot;&gt;$\text{CO}_{2}$&lt;/span&gt; forms around &lt;a href=&quot;http://www.google.co.in/patents/US6877698&quot; rel=&quot;noreferrer&quot;&gt;50% to 75%&lt;/a&gt; of the mixture.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;The amount of gas required for inflation of the slides in the aircraft is quite high. If all these are carried in pressure vessels, either of the following has to be done&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;increase the pressure (already &lt;span class=&quot;math-container&quot;&gt;$\sim200$&lt;/span&gt; bar) of the gas in the vessel (its usually in liquid form), which increases the pressure vessel thickness and consequently the weight, or&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;increase the number or size of pressure vessels, which again increases the weight.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Also, a gas generator (usually pyrotechnic) can be used, which generates gas by exothermic reaction. This too, has its disadvantages:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The gas generated is at high temperature (via thermionic reaction), resulting in damage to the slide fabric.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, as the gas cools, the evacuation slide may sag (as gas contracts). This is not good as the slides are expected to act as life rafts.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The size of the gas bottle can also be reduced by using an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aspirator_%28pump%29&quot; rel=&quot;noreferrer&quot;&gt;aspirator&lt;/a&gt;, which draws in ambient air to mix in a ratio of about two-thirds air to one-third gas from the bottle.&lt;/p&gt;&#xA;&lt;p&gt;To overcome these, the aircraft slide inflation system uses is hybrid system that uses two techniques:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Instead of carrying the gas itself, carry a compound capable of undergoing thermal decomposition such that the number moles of gas produced by the inflator is greater than the number of moles of gas stored. Nitrous oxide is used because of manufacturability, storage and handling concerns.&lt;/p&gt;&#xA;&lt;p&gt;Two moles of Nitrous Oxide &lt;span class=&quot;math-container&quot;&gt;$\text{N}_{2}\text{O}$&lt;/span&gt;, when undergoing thermal decomposition, forms two moles of diatomic nitrogen (&lt;span class=&quot;math-container&quot;&gt;$\text{N}_{2}$&lt;/span&gt;) and one mole of diatomic oxygen (&lt;span class=&quot;math-container&quot;&gt;$\text{O}_{2}$&lt;/span&gt;)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$2\text{N}_{2}\text{O} \ = \ 2\text{N}_{2} \ + \ \text{O}_{2}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Because the universal gas constant is the same for all gases, the three moles of nitrogen and oxygen produced by the decomposition of two moles of nitrous oxide occupy 50% more volume than the two moles of nitrous oxide would have occupied at the same temperature and pressure. Thus, the size of the container is reduced by a third (compared to situation where we use undecomposed gas).&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A pyrotechnic gas generator (or an aspirator) that augments the stored compressed gas by providing additional gas.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;For more details, see US patent application US 6877698 B2, &lt;a href=&quot;http://www.google.co.in/patents/US6877698&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;Aircraft evacuation slide inflation system using a stored liquified gas capable of thermal decomposition&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;In case the amount of gas required is low (for example, in some helicopters), only the pressure bottles are carried.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-23T14:09:21.570" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23099" PostTypeId="1" CreationDate="2015-11-22T05:35:43.283" Score="14" ViewCount="11412" Body="&lt;p&gt;I've always wondered how airlines transfer bags between connecting flights. At a hub, bags must be moved to any number of connecting flights throughout the airport - some with very short connecting times. Seems like sorting them would take a lot of time. How does this process happen? &lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2019-07-09T13:36:08.460" Title="How is passenger baggage transferred, and how does it happen so quickly?" Tags="&lt;airport&gt;&lt;ground-operations&gt;&lt;baggage-handling-system&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23100" PostTypeId="2" ParentId="23099" CreationDate="2015-11-22T07:57:02.213" Score="4" Body="&lt;p&gt;In case of connecting flights in same airline or between partner airliners which allow baggage transfer, the baggage is usually checked in for the duration of the journey i.e. from source to destination.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case the time between interconnecting flight is short, someone (usually airline agent) picks up the luggage from the the aircraft and loads it into the connecting flight. If I understand correctly, such cases are marked in their tags so as to allow for proper storage in cargo hold (for easy retrieval). &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i1LFn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i1LFn.jpg&quot; alt=&quot;Luggage transfer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transfer of luggage into a flight, from denverpost.com.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/196313/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this forum&lt;/a&gt; says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most US airline tags will either be a 'city', 'hot' or 'cold'. City is a bag going straight to where the flight is going. Hot and cold are bags that are connecting onto another flight, depending on the amount of time between flights. Hot bags are usually loaded separately and are the last ones loaded onto the flight so that they are the first ones off at the destination and they can make the connecting flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BsRwh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BsRwh.jpg&quot; alt=&quot;Hot tag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: australianfrequentflyer.com.au &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, SWA put a single driver in charge of collecting all the baggage for a particular outbound flights &lt;a href=&quot;http://www.denverpost.com/ci_16175981&quot; rel=&quot;nofollow noreferrer&quot;&gt;from all the inbound ones&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case there is sufficient time between connecting flights, the agent (who has a list of baggage to be transferred) unloads the baggage and loads it into the airport baggage control system, which then sorts it automatically into the correct aircraft. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Having the bags in ULD (unit load device) operates in the same way. Each bag bar code tag triggers the opening/closing of a &quot;door&quot; on its way so, after a few branchings it arrives into a &quot;sorter&quot; which sends it into a particular container.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course, this assumes that there is no security checks involved in the middle (like in international flights). In that case, the system is similar, but involves screening.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-22T13:19:33.720" LastActivityDate="2015-11-22T13:19:33.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23101" PostTypeId="2" ParentId="23091" CreationDate="2015-11-22T08:22:53.023" Score="3" Body="&lt;p&gt;In most helicopters, the wind direction when hovering is of concern to the pilot, as is which way you turn when hovering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following applies to a single rotor helicopter with the tail rotor mounted on the left and the rotor turning counter-clockwise.  The opposite applies to clockwise rotating rotors and mounting the tail rotor on the left versus on the right would take more pages of text!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hover with no wind.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As the rotor rotates counter-clockwise, the torque reaction on the fuselage wants to turn the nose to the right.  The tail rotor &quot;pushes&quot; the tail to the right to balance this torque.  It is by varying the angle of attack of the tail rotor that we can change the amount of thrust from the tail rotor and therefore have yaw control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail rotor is no different to the main rotor, it just operates in the Y axis rather than the Z axis and is subject to &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_ring_state&quot; rel=&quot;nofollow&quot;&gt;vortex ring state&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vortex from the tail rotor is to the left.  If the helicopter is yawed right, the tail moves left and the tail rotor moves into it's own vortex causing a reduction in angle of attack and therefore thrust.  If the turn is too fast, this reduction can lead to a loss of tail rotor effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also in a no wind hover, the vortex from the main rotor is forced downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of what follows is for a counter-clockwise rotating rotor and applies to all single rotor helicopters.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hover with the nose into wind, but not with enough wind to generate&#xA;  &lt;a href=&quot;https://en.wikipedia.org/wiki/Translational_lift&quot; rel=&quot;nofollow&quot;&gt;effective translation lift&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This state is more or less the same as for a no wind hover and is the easiest (and therefore preferred) direction in which to hover.  Turning the aircraft has the same risk as in a no wind hover in that turning too quickly to the right can lead to loss of &lt;a href=&quot;https://en.wikipedia.org/wiki/Loss_of_tail-rotor_effectiveness&quot; rel=&quot;nofollow&quot;&gt;tail rotor effectiveness&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hover into wind with enough wind speed to generate translational lift&#xA;  (let's say about 15 kts)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now things start to get interesting.  If you turn to the left, the vortex from the front edge of the main rotor is blown backwards by the wind across the tail rotor and causes a decrease in the angle of attack of the tail rotor blades since the wind from the vortex is blown on to the right hand side of the tail rotor.  Therefore, a lot more left pedal is required as the helicopter turns from 0 degrees (relative to the wind) to 270 degrees.  As 270 degrees is reached and passed, the vortex is no longer interfering with the tail rotor and the angle of attack for the same pedal position is increased.  If the same pedal input is maintained, the rate of turn will increase rapidly and if not corrected, can lead to an uncontrolled spin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you turn to the right, the opposite happens.  More right pedal (less thrust) is required in the first quadrant of the turn from 0 degrees to 90 degrees since the vortex is blown into the face of the tail rotor causing an increase in angle of attack and therefore greater thrust.  As the nose passes 90 degrees, the angle of attack decreases and left pedal must be added to prevent a sudden acceleration in yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should be able to see that the amount of pedal required changes as the turn continues and without constant adjustment, a steady turn cannot be maintained and with enough wind, and a pilot who is not quick enough on the pedals, control can be lost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's take the turn out of the equation and consider steady hovers in wind that is not &quot;on the nose&quot;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wind from the left quarter, i.e. 270 - 0 degrees. This is effectively the same condition as that first quarter of a left turn with wind from the front.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the difficult one.  Wind is never constant. It is always changing slightly and turbulent.  As the main rotor vortex is blowing into the tail rotor, the tail rotor is operating in a very turbulent and unpredictable environment.  Rapid and constant pedal inputs are required to maintain control.  Any deviation not caught immediately can lead to a loss of control.  It is very difficult to hover with the wind from the left quadrant and is therefore usually avoided.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wind generally from the left (a left crosswind)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As the wind is blowing into the face of the tail rotor, its angle of attack is reduced as the airspeed through the rotor increases.  This can lead to the loss of tail rotor effectiveness or even a stall of the blades as the angle of attack exceeds the critical angle.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wind from behind.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The primary effect here is the tendency of the fuselage and vertical stabiliser to &quot;weather cock&quot; the aircraft.  It naturally wants to face into wind.  If a yaw begins and is not immediately corrected, due to the effects above, the yaw can increase rapidly and suddenly.  Additionally, the wind is never constant and varies between passing to the left and to the right of the tail rotor.  Therefore, hovering downwind needs immediate and constant corrections to yaw.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Summary&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Hovering into wind is very much preferred and is always chosen unless operations require something different.  Hovering with the wind from the right is the next &quot;most&quot; preferred position with quartering winds from the left and hovering downwind to be avoided if possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of this said, it's a standard part of training to learn how to hover in these conditions and how to maintain constant rate turns.  It does require a lot of learned skill and you must be quick and accurate on the pedals with constant corrections. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, early models of the UH-1 were particularly difficult to handle in certain wind conditions and the tail rotor was moved from the right to the left on later models to improve handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a light helicopter with little power reserve, e.g. the R22, hovering in strong gusty winds is an intense part of operations.  I had some close calls when learning how to do this including a loss of control which I only recovered by pulling in power and accelerating into forward flight.  Not good on an airfield with other aircraft operating since my &quot;low hours brain&quot; focussed only on regaining control.  I am ashamed to say that looking around took second place but I did learn an important lesson and with hindsight, the right thing to do would have been to land and discontinue the flight as the wind got more gusty.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-22T16:25:11.897" LastActivityDate="2015-11-22T16:25:11.897" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23102" PostTypeId="2" ParentId="23091" CreationDate="2015-11-22T08:24:59.513" Score="0" Body="&lt;p&gt;The helicopter does not differentiate between the wind and flight. i.e. it does not matter if the helicopter is flying in a direction or the wind is coming from that direction. As with landing, visibility is the primary concern for the pilot during hover (or maintaining a position, like during a rescue).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it better to hover into the wind rather than other positions for aerodynamic and stability reasons.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of wind from left of the front ~285° to 315° (if the main rotor is rotating clockwise from the top) , the vortex from the main rotor can interfere with the tail rotor, reducing its effectiveness. This may cause an uncommanded rapid rotation, which can lead to loss of control if not corrected.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AXq6T.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AXq6T.gif&quot; alt=&quot;Vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: dynamicflight.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case there is a tailwind, the helicopter vertical tail (and fuselage) may align try to align with the wind, resulting in uncommanded yaw. If not corrected with proper pedal input, this &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20030520X00704&amp;amp;key=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;may lead to loss of control.&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i9Pln.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i9Pln.gif&quot; alt=&quot;Stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: morningtonsanfordaviation.com &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of cross wind (from the left for main rotors rotating clockwise from top), the tail rotor may enter into a vortex ring state, especially in low speeds. This requires continual adjustment of pedals by the pilot to prevent the unsteady yaw.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nItuo.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nItuo.gif&quot; alt=&quot;Lte- vortex&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: morningtonsanfordaviation.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This should apply for both in and out of ground cases. It is usually preferable to orient the helicopter so that the thrust required from the tail rotor is minimized in case of a cross wind i.e. so that the cross wind is from the right in case the main rotor rotation is clockwise from the top. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-22T08:24:59.513" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23103" PostTypeId="2" ParentId="22983" CreationDate="2015-11-22T08:27:02.257" Score="-6" Body="&lt;p&gt;I don't fly but I would guess it would be the same as computer programming.  The pilots probably learn a set of commands that ATC will give them, these commands will be a standard set around the world, so it won't necessarily be &quot;English&quot; that is spoken on the radio, more an international code language.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I did amateur radio we had various Q-codes and number codes like 73's, 88's, QTH, QRZ - all these meant the same no matter which country you were from and that way we could speak to each other regardless of language, and it was it's own language known mainly by the amateur radio community.  I would guess that pilots have the same thing - for example in amateur radio the following would mean&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1: QTH? &#xA;2: QTH Berlin&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1: Where are you?&#xA;2: I'm in Berlin&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know whether pilots use Q codes but I guess they must have something similar to this&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also there has been other things that have used these radio codes - for example the messenger service ICQ was named because the code for calling for a response on radio is to CQ (&quot;Seek You&quot;) someone - &quot;CQ, CQ, this is GW0AAA /MM calling CQ&quot; means that someone with the call sign of G0AAA is in Wales on a boat of some sort and they're calling out to anyone who may be interested in having a chat (also the callsign gives you additional information about the person your speaking to - I assume pilots have similar things a callsign that starts G or M indicates that the persons amateur radio licence is from the UK, the second letter is used to indicate which part of the UK the person is calling from - England doesn't have a secondary letter but Wales has W, Scotland is M, NI is I, IoM (D), Guernsey (U) and Jersey (J) are also included even though technically they're separate from the UK with their own government) and the end bit also tells the person even more information - for example /M = the person is mobile, /T they're in a temporary location, /MM is maritime mobile, etc - but with all that extra information you don't really need to know English to work out roughly where that person is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And finally with modern translation services and computer systems I would also guess that anything that comes through the radio now on a plane would also probably be sent to a screen on the dashboard, which has the ability to translate - just a guess but can't see why this isn't incorporated into planes (it is on Microsoft Flight Sim and that's supposed to be &quot;As Real As It Gets!&quot; - although I have heard that XPlane is much more real!) - and it wouldn't need to be a very big dictionary of words either for translation because there would only be a select number of phrases you'd need, your not really going to sit there and have a full on conversation with ATC are you - both them and you want to keep communication short and to the point because other people also need to use the radio comms.&lt;/p&gt;&#xA;" OwnerUserId="12374" LastActivityDate="2015-11-22T08:27:02.257" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23104" PostTypeId="2" ParentId="23096" CreationDate="2015-11-22T09:45:18.920" Score="65" Body="&lt;p&gt;Let me first give some background information on the art of inflating an evacuation slide. There are two ways to fill them:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Expand gas from a high-pressure bottle: This will cool the gas as it expands, so ice may form at the aspirator outlets where sucked-in air and the expanding gas mix, blocking the flow of outside air into the slide. Also, storing compressed gas needs bulky and heavy steel vessels.&lt;/li&gt;&#xA;&lt;li&gt;Pyrotechnic gas generators which use an exothermic reaction to create a large amount of hot gas. They are more compact and lighter than a pressure vessel for the same amount of gas produced, but their hot gas could scorch the slide material and will contract when it cools down after the filling process, so a slide filled by a pyrotechnic gas generator will sag after a while.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Because of the disadvantages of both pure stored gas and pure pyrotechnic inflation devices, current state of the art emergency evacuation slide systems use a hybrid inflator, which comprises a stored compressed gas together with a pyrotechnic gas generator. The pyrotechnic gas generator augments the stored compressed gas by providing additional gas as well as heat to counteract the effects of the expansion-induced cooling of the compressed gas as it expands out of the pressure vessel.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Operation of a hybrid inflator&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The typical gas generator uses solid &lt;a href=&quot;https://en.wikipedia.org/wiki/Ammonium_nitrate&quot; rel=&quot;noreferrer&quot;&gt;ammonium nitrate&lt;/a&gt; which is electrically ignited and produces nitrous oxide (N$_2$O) and water (H$_2$O) when heated. Nitrous oxide will exothermically decompose into nitrogen and oxygen when heated above 650°C or 1200°F, so even more energy and gas is produced. Note that the decomposition of two &lt;a href=&quot;https://en.wikipedia.org/wiki/Mole_(unit)&quot; rel=&quot;noreferrer&quot;&gt;moles&lt;/a&gt; of nitrous oxide will produce two moles of nitrogen (N$_2$) plus one mole of oxygen (O$_2$), thus adding 50% more gas volume. This hot mixture of nitrogen, oxygen and steam is then piped into the pressure vessel and mixes with the gas flowing out from it, thereby heating the emitted gas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure vessel contains gasses like nitrogen or carbon dioxide. Other candidates are argon or helium, but their higher price has held them back. To increase the yield from the pressurized gas, the trick with the nitrous oxide can be repeated here: By storing nitrous oxide in the pressure vessel, again 50% more gas volume can be produced from what is stored, while the exothermic decomposition produces additional heat that offsets, to some extent, the heating of the stored gas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nitrous oxide is also attractive because it offers the best manufacturability, storage and handling of the possible decomposable gas source materials. Although classified as an oxidizer, in practice it is generally nontoxic and non-corrosive and is relatively inert up to temperatures of about 200°C. Also, nitrous oxide, as compared to gases such as oxygen, nitrogen and argon, liquefies relatively easily at ambient temperatures - helpful when the gas in the pressure vessel is stored in liquefied form to reduce its bulk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heated to its decomposition temperature, pure nitrous oxide will undergo a rapid &lt;a href=&quot;https://en.wikipedia.org/wiki/Dissociation_(chemistry)&quot; rel=&quot;noreferrer&quot;&gt;disassociation&lt;/a&gt; chain reaction unless a coolant gas is added to absorb some of the heat generated by the exothermic reaction. Therefore, the mixture in the pressure vessel contains 50% or more of carbon dioxide which has a latent heat of vaporization of approximately 66 Calories per gram. As a three-atomic gas it is better suited for this task than two-atomic alternatives. Thus, it does not serve as a diluent (as aeroalias wrongly states), it absorbs heat and stabilizes the disassociation process.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why a mixture of nitrogen and carbon dioxide&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now we can answer your question: Nitrogen is contributed both by the pyrotechnic gas generator and by the compressed gas and is produced from the dissociation of nitrous oxide (N$_2$O). Carbon dioxide is added to dampen the exothermic dissociation and absorb some of the heat produced. Without it, the gas generator would experience a runaway chain reaction! Its concentration in the compressed gas is between 50% and 75%, so the concentration in the gas generator mix is around 35% to 50%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high speed flow of gas from the pressure vessel is now piped through an aspirator, which sucks in ambient air by using the Venturi effect, and from there into the slide. This contributes up to three quarters of the total gas in the slide, so most of the nitrogen in the slide is from ambient air. In the slide, the concentration of carbon dioxide is diluted to around 10% to 15%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ROqLO.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ROqLO.png&quot; alt=&quot;Aspirator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aspirator (from BF Goodrich's &lt;a href=&quot;http://pdfpiw.uspto.gov/.piw?Docid=04368009&amp;amp;homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO2%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526co1%3DAND%2526d%3DPTXT%2526s1%3D4368009.PN.%2526OS%3DPN%2F4368009%2526RS%3DPN%2F4368009&amp;amp;PageNum=&amp;amp;Rtype=&amp;amp;SectionNum=&amp;amp;idkey=NONE&amp;amp;Input=View%20first%20page&quot; rel=&quot;noreferrer&quot;&gt;US Patent 4368009&lt;/a&gt;). High-speed gas from the gas generator (red arrows) enters from the angled pipe on the left and pulls ambient air (blue arrows) with it when shooting from the nozzles on the right. Contrary to aeroalia's claims, an aspirator is not just another name for a gas generator, it is an entirely different thing altogether.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-22T21:24:18.737" LastActivityDate="2015-11-22T21:24:18.737" CommentCount="21" ContentLicense="CC BY-SA 3.0" />
  <row Id="23105" PostTypeId="2" ParentId="23099" CreationDate="2015-11-22T12:54:17.363" Score="12" Body="&lt;p&gt;On big airliners, baggage is mostly stowed in containers, called &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;Unit Load Device&lt;/a&gt;s. They are packed at the departure airport and pre-sorted to minimize the amount of sorting at a hub, but normally need to be emptied after arrival so the baggage can be re-sorted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On regional jets and older aircraft which don't take ULDs, bags are still loaded individually and transported to and from the aircraft on open carts which are assembled to small trains (see picture below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4eHmt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4eHmt.jpg&quot; alt=&quot;Airport baggage transportation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport baggage transportation (picture &lt;a href=&quot;http://cdn.c.photoshelter.com/img-get/I0000fE.A14txsPI/s/750/600/Transportation-Airport-Luggage-JN1108230004.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the ULDs or the carts arrive inside the terminal, the bags are unloaded into the &lt;a href=&quot;https://en.wikipedia.org/wiki/Baggage_handling_system&quot; rel=&quot;noreferrer&quot;&gt;baggage handling system&lt;/a&gt;, a collection of conveyor belts, barcode readers and switch points. Since every bag received a sticker with a big barcode upon check-in, the reader can report the barcode of the next bag to a computer wich sets the switch point accordingly. Traditional systems employ humans with a portable barcode reader for putting the bags on the right belts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bz9Uo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bz9Uo.jpg&quot; alt=&quot;Baggage tags&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Baggage tags (picture &lt;a href=&quot;http://www.airport-suppliers.com/content_images/supplier/Baggage_Tags_Airline_Documents_CheckIn_Material_Boarding_Passes_RFID_CUSS_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most recent systems put the bags on plastic trays which have &lt;a href=&quot;https://en.wikipedia.org/wiki/Radio-frequency_identification&quot; rel=&quot;noreferrer&quot;&gt;RFID tags&lt;/a&gt; attached, and the RFID information is used for switching the conveyor belts. By loading the bags on standard size trays, the flow of bags is simplified. However, a baggage handling system is a complex piece of machinery, and some new airport terminals were delayed because the system did not work initially, or opened with lots of mis-routed or even mangled bags in their first months of operation. &lt;a href=&quot;http://news.bbc.co.uk/2/hi/uk_news/7322453.stm&quot; rel=&quot;noreferrer&quot;&gt;London's Terminal 5&lt;/a&gt; and &lt;a href=&quot;http://calleam.com/WTPF/?page_id=2086&quot; rel=&quot;noreferrer&quot;&gt;Denver airport&lt;/a&gt;, which went back to &lt;a href=&quot;http://www.nytimes.com/2005/08/27/us/denver-airport-saw-the-future-it-didnt-work.html?_r=0&quot; rel=&quot;noreferrer&quot;&gt;manual sorting after 10 painful years&lt;/a&gt; of trying to get their system working, come to mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When they are sorted, the bags are deposited either at a ULD packing station or an empty cart for transportation to their respective flight. At the end of their journey, they are routed onto &lt;a href=&quot;https://en.wikipedia.org/wiki/Baggage_carousel&quot; rel=&quot;noreferrer&quot;&gt;baggage carousel&lt;/a&gt;s for pick-up by their owners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bYz52.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bYz52.jpg&quot; alt=&quot;Baggage carousel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Baggage carousel (picture &lt;a href=&quot;http://cdn.images.express.co.uk/img/dynamic/1/590x/baggage-carousel-419941.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-22T20:19:28.210" LastActivityDate="2015-11-22T20:19:28.210" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23107" PostTypeId="1" AcceptedAnswerId="23108" CreationDate="2015-11-22T20:41:11.087" Score="5" ViewCount="2711" Body="&lt;p&gt;I've gotten this question wrong multiple times on practice tests. Sporty's study buddy claims the information is sourced from AIM 7-1, but it's nowhere to be found.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Correct answers included:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The intended route of flight and destination&lt;/li&gt;&#xA;&lt;li&gt;Tail number&lt;/li&gt;&#xA;&lt;li&gt;Identify themselves as pilots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What is the actual authoritative language that covers this test question?&lt;/p&gt;&#xA;" OwnerUserId="5679" LastEditorUserId="5679" LastEditDate="2015-11-22T21:29:54.947" LastActivityDate="2015-11-22T21:29:54.947" Title="What should pilots state initially when telephoning a weather briefing facility for preflight weather information?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;aim&gt;&lt;fss&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23108" PostTypeId="2" ParentId="23107" CreationDate="2015-11-22T20:57:09.180" Score="6" Body="&lt;p&gt;It's in &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;the AIM&lt;/a&gt; 5-1-1(f):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When requesting a preflight briefing, identify yourself as a pilot and&#xA;provide the following:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Type of flight planned; e.g., VFR or IFR.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft’s number or pilot’s name.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft type.&lt;/li&gt;&#xA;&lt;li&gt;Departure Airport.&lt;/li&gt;&#xA;&lt;li&gt;Route of flight.&lt;/li&gt;&#xA;&lt;li&gt;Destination.&lt;/li&gt;&#xA;&lt;li&gt;Flight altitude(s).&lt;/li&gt;&#xA;&lt;li&gt;ETD and ETE&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Personally, I've never given or been asked for the aircraft type (although I have it on my &lt;a href=&quot;https://www.1800wxbrief.com&quot; rel=&quot;noreferrer&quot;&gt;LMFS&lt;/a&gt; profile so they should have it), but the other items come up. My typical request is something like this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This is N12345, I'd like a standard briefing for a VFR flight from&#xA;KMDQ to KLOU at 5500', ETD at 1600Z, ETE 2h15&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-22T20:57:09.180" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23109" PostTypeId="2" ParentId="23058" CreationDate="2015-11-22T22:56:14.890" Score="7" Body="&lt;p&gt;RTCA documents are not FAA documents, although the FAA is usually a member of the Special Committee that creates the documents. If an example is to be added, it is the decision of the SC, not of the FAA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason that no examples are given is that the recommendation is clear by itself. A good V&amp;amp;V engineer will read this recommendation and use his skill, experience and creativity to find an other acceptable means to validate the software requirements that can not be validated in a realistic environment. This alternative means is then documented in the SVP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Giving an example is not helpful at all, since the solution will depend completely on the software under test and the nature of the requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the hardware is not available, an emulator may be the solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other cases artificial test inputs have to be generated, because failing a test in a realistic environment may prove to be catastrophic. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="7532" LastEditDate="2015-11-23T01:00:17.337" LastActivityDate="2015-11-23T01:00:17.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23110" PostTypeId="1" CreationDate="2015-11-23T03:32:55.203" Score="1" ViewCount="123" Body="&lt;p&gt;I've looked up a few different regulations (FAA) regarding the logging of time in my logbook and am unclear on how to log my time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the scenario: I am a private pilot and am getting checked out on a new aircraft. I am sitting in the left seat and am legal to operate the aircraft currency/certificate-wise, but a CFI is taking me through the motions with a new plane. How should I log this? Dual, PIC, or both? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, here's scenario two: everything is same as in the above scenario except I am getting checked out on a complex aircraft for my complex endorsement. How should I log this?&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-11-23T03:32:55.203" Title="Can you log PIC for dual time after you have your PPL?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-11-23T06:54:18.307" ContentLicense="CC BY-SA 3.0" />
  <row Id="23111" PostTypeId="1" AcceptedAnswerId="23159" CreationDate="2015-11-23T03:42:04.793" Score="3" ViewCount="2244" Body="&lt;p&gt;I am a student pilot at ABX (&lt;a href=&quot;https://skyvector.com/airport/YMAY/Albury-Airport&quot; rel=&quot;nofollow&quot;&gt;YMAY&lt;/a&gt;) in Australia. It is a single engine aerodrome with three frequencies:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;123.25;&lt;/li&gt;&#xA;&lt;li&gt;125.80; and &lt;/li&gt;&#xA;&lt;li&gt;the ATIS frequency&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I live very close to the airport, directly under the base/final turn. Would I be able to purchase a handheld radio that I could use to listen to the ATC and practise my radio calls? Is it legal?&lt;/p&gt;&#xA;" OwnerUserId="11873" LastEditorUserId="1696" LastEditDate="2016-07-06T21:34:44.393" LastActivityDate="2016-07-06T21:42:34.140" Title="Is it legal to use handheld radios to listen to airport frequencies in Australia?" Tags="&lt;air-traffic-control&gt;&lt;radio&gt;&lt;australia&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23112" PostTypeId="1" AcceptedAnswerId="23115" CreationDate="2015-11-23T05:39:59.737" Score="0" ViewCount="513" Body="&lt;p&gt;What is the maximum achievable Mach number for a titanium aircraft assuming speed is limited by structural heating?  The answer would be even better if there is a list of different materials and maximum Mach numbers.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-11-23T16:06:39.057" Title="What is the maximum Mach number for a titanium aircraft?" Tags="&lt;airframe&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2015-11-23T12:53:34.057" ContentLicense="CC BY-SA 3.0" />
  <row Id="23113" PostTypeId="2" ParentId="23111" CreationDate="2015-11-23T09:41:36.110" Score="0" Body="&lt;p&gt;I'm sure it would be legal in Australia to buy a scanner to listen to the aviation band. If you want one that transmits you will probably need a license to operate it if not buy it, but then you really don't want to be transmitting anyway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I would not think it's worth the money. Listening can be interesting but it gets old quickly and you don't learn as much as you might expect - RT work makes more sense in context. My personal experience is that the hard part of RT is not knowing what to say but getting it out in the cockpit when you are also flying and navigating as the same time, and that only comes with experience. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are taking lessons why not ask if you can borrow a handheld radio from your training organization? They probably have one or two lying around. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-23T09:41:36.110" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23115" PostTypeId="2" ParentId="23112" CreationDate="2015-11-23T11:08:44.547" Score="7" Body="&lt;p&gt;To give an answer, I first need to get answers to a few more questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First question:&lt;/strong&gt; Which &lt;a href=&quot;http://www.azom.com/article.aspx?articleid=1341&quot; rel=&quot;nofollow noreferrer&quot;&gt;titanium alloy&lt;/a&gt; would you consider? The choice of alloy will impact the answer much more than the base metal of the selected alloy. Since strength at elevated temperature is the figure of merit here, consider the spread of values:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fKa97.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fKa97.gif&quot; alt=&quot;Ti alloy strength over temperature&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strength of various Ti alloys over temperature (picture &lt;a href=&quot;http://www.azom.com/article.aspx?articleid=1341&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second question:&lt;/strong&gt; Which cooling is available? Is the aircraft propelled by liquid hydrogen which has a &lt;a href=&quot;http://www.engineeringtoolbox.com/specific-heat-capacity-gases-d_159.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;massive heat capacity per kilogram of mass&lt;/a&gt; and needs to be heated before it is injected into the combustion chamber. Or do you run it on kerosene, which allows to dump much less heat into it? The answer will tell you how much cooler the structure can be than the air flowing around it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Third question:&lt;/strong&gt; What wing loading is possible? This is driven by the range and payload requirements of the aircraft, and your question doesn't give any details on this. A higher wing loading will translate into a higher heat flow since the air density needs to be higher, so the cooling can be less effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fourth question:&lt;/strong&gt; Do you insist on an attached shock which produces much higher peak temperatures in parts of the structure, but less thermal load overall, or is a separated shock possible which increases drag and thermal load, but reduces peak loads considerably?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the answers to those questions, the possible flight Mach number can be anywhere between Mach 2 and Mach 5. If you allow for specialty materials for highest thermal loads and make only the inner structure from titanium, the Mach number can reach into double digits.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-23T16:06:39.057" LastActivityDate="2015-11-23T16:06:39.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23116" PostTypeId="2" ParentId="23024" CreationDate="2015-11-23T11:47:28.057" Score="0" Body="&lt;p&gt;The design of the cockpit itself shows that there is a procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look in places like Airliners.net the upper panel in an Airbus, you will find that the extinguishers have a cover to prevent the unintentional activation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, a common approach is asking the pilot monitoring for confirmation about which engine has problems before pressing the button. Of course, to make it work, it has to be emphasized in the training process. I have been a witness in a situation where the pilot asking for confirmation had already the finger on the switch...if that is not corrected, you can be sure that, whatever the answer of the other pilot should be, he would press that button.&lt;/p&gt;&#xA;" OwnerUserId="12383" LastActivityDate="2015-11-23T11:47:28.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23117" PostTypeId="1" CreationDate="2015-11-23T16:21:18.917" Score="51" ViewCount="32836" Body="&lt;p&gt;If you look at this picture below, you will notice that the &lt;strong&gt;nose portion&lt;/strong&gt; of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21&quot; rel=&quot;noreferrer&quot;&gt;Mig-21&lt;/a&gt; has a unique conical shape which is completely different from the nose of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;noreferrer&quot;&gt;F-16&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EbTzG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EbTzG.jpg&quot; alt=&quot;Mig-21&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://www.worldwide-military.com/Military%20Aircraft/Russian%20Fighters/MIG-21_Algemene_info_english.htm&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6ekyJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6ekyJ.jpg&quot; alt=&quot;F-16&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://www.radioiowa.com/2013/09/08/iowa-air-guard-marks-end-of-72-years-of-manned-flight-in-des-moines/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what explains the conical design of the nose of the Mig-21?&lt;/p&gt;&#xA;" OwnerUserId="9142" LastEditorUserId="14897" LastEditDate="2017-05-13T12:52:01.237" LastActivityDate="2019-01-27T19:06:19.557" Title="Why is the nose of the Mig-21 shaped so differently compared to other fighter aircraft?" Tags="&lt;aircraft-design&gt;&lt;f-16&gt;&lt;nose&gt;&lt;mig-21&gt;" AnswerCount="12" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23118" PostTypeId="2" ParentId="23117" CreationDate="2015-11-23T16:25:03.853" Score="14" Body="&lt;p&gt;It is the intake of the jet engine which gives it that shape, a good number of earlier jet fighter planes did have that configuration. The pointed part is the shock cone for when the plane flies supersonic so that the shock would not mess with the aerodynamics of the plane especially inside the engine.&lt;a href=&quot;https://i.stack.imgur.com/iQ23G.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iQ23G.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image by USAF&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-24T00:45:05.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23121" PostTypeId="2" ParentId="23117" CreationDate="2015-11-23T18:29:49.880" Score="39" Body="&lt;p&gt;A lot of early jet aircraft had the intake in the nose.  Here's a few more examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1aipm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1aipm.jpg&quot; alt=&quot;F-86 Sabre&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7UPol.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7UPol.jpg&quot; alt=&quot;Mig-17&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rluAD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rluAD.jpg&quot; alt=&quot;F-84&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cone in the front is required because the Mig-21 is a supersonic aircraft.  The cone breaks the shockwave so that the inlet air is sub-sonic.  The SR-71 is a very different type of aircraft but you can see that its engines have a very similar style of inlet: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sk2sX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sk2sX.jpg&quot; alt=&quot;SR-71&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7752" LastActivityDate="2015-11-23T18:29:49.880" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23122" PostTypeId="2" ParentId="23117" CreationDate="2015-11-23T19:13:03.313" Score="3" Body="&lt;p&gt;I'm not an aircraft designer, but I'm pretty sure I've figured out the design philosophy that led to that nose.  The aircraft has one engine, which is positioned along the aircraft's central axis.  Since it's a jet engine, it needs an intake.  The simplest intake design is a straight tube.  Due to the positioning of the engine, this puts the intake's inlet right at the nose.  As others have mentioned, the cone in the center of the inlet is present in the MiG-21 but not, for example, the F-86 Sabre, because the MiG-21 is a supersonic aircraft, and the F-86 isn't.&lt;/p&gt;&#xA;" OwnerUserId="12388" LastActivityDate="2015-11-23T19:13:03.313" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23124" PostTypeId="2" ParentId="23117" CreationDate="2015-11-23T22:33:20.960" Score="11" Body="&lt;p&gt;A lot of supersonic aircraft of the era had the same kind of intake, the English Electic Lightning off the top of my head:&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/EE_Lightning_F6_XS904_BQ_%287173122840%29.jpg/1024px-EE_Lightning_F6_XS904_BQ_%287173122840%29.jpg&quot; alt=&quot;&quot;&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.flickr.com/photos/ajw1970/7173122840/&quot; rel=&quot;noreferrer&quot;&gt;EE Lightning F6 'XS904 / BQ'&lt;/a&gt; by &lt;a href=&quot;https://www.flickr.com/people/65001151@N03&quot; rel=&quot;noreferrer&quot;&gt;Alan Wilson&lt;/a&gt; is licensed under &lt;a href=&quot;http://creativecommons.org/licenses/by-sa/2.0&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 2.0&lt;/a&gt;&lt;/sup&gt;&lt;br&gt;&#xA;The cone is to slow down the supersonic airflow, so that the air is relatively calm when it goes into the turbine, which ensures a smooth burn. It's in the nose so that the air duct is straight, because, without computer modelling it took a lot of trial and error to design curved air intakes (e.g. in the wings).&lt;/p&gt;&#xA;" OwnerUserId="12392" LastEditorUserId="2171" LastEditDate="2015-11-24T12:21:44.997" LastActivityDate="2015-11-24T12:21:44.997" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23125" PostTypeId="1" AcceptedAnswerId="23128" CreationDate="2015-11-23T22:33:50.230" Score="4" ViewCount="549" Body="&lt;p&gt;I'm a member of a student competition team, we design light aircraft (total airplane overhead area is limited to 0.9 m²) capable of carrying higher payload. The competition also limits the takeoff distance (this year's limit was 70 m).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Coming from the last event, we decided that winglets are probably a great introduction to the project, but we have no idea how to design one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is basically: with this kind of aircraft (weighs about 2.3 kg empty, carries about 13 kg, wingspan is 2.8 m), what should we look for in a winglet design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We are mostly in doubt about what kind of airfoil should we use. Should we look for less drag? More efficiency? How can we maximize the traction vector, and should we do that in first place?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have been reading papers on the subject, but with little luck. We also don't think it would be wise to just randomly test things until we get right, so a little bit of direction would help a lot, even if it's an article that we should work around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance!&lt;/p&gt;&#xA;" OwnerUserId="12391" LastEditorUserId="1696" LastEditDate="2015-11-25T20:11:29.117" LastActivityDate="2015-11-25T20:11:29.117" Title="How can I get started on a winglet design for a small remote controlled aircraft?" Tags="&lt;aircraft-design&gt;&lt;winglets&gt;&lt;model-aircraft&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23126" PostTypeId="2" ParentId="23117" CreationDate="2015-11-24T00:10:28.570" Score="60" Body="&lt;p&gt;The nose design of aircraft, like any other part, is a result of optimization in response to a number of factors. The Mikoyan-Gurevich MiG-21 'Fishbed' is a supersonic, second/third generation Soviet fighter/interceptor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first jet aircraft to enter serice during the WWII, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt Me 262 'Schwalbe'&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Gloster_Meteor&quot; rel=&quot;noreferrer&quot;&gt;Gloster Meteor&lt;/a&gt; had twin engines in their wings. In these cases, the nose was designed to carry the cannons, which were the primary armament at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/11lYN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/11lYN.jpg&quot; alt=&quot;Me 262&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Messerschmitt_Me_262A_at_the_National_Museum_of_the_USAF.jpg#/media/File:Messerschmitt_Me_262A_at_the_National_Museum_of_the_USAF.jpg&quot; rel=&quot;noreferrer&quot;&gt;Messerschmitt Me 262A at the National Museum of the USAF&lt;/a&gt;&quot; by USAF museum - &lt;a href=&quot;http://www.nationalmuseum.af.mil/shared/media/photodb/photos/040820-F-1234P-081.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://www.nationalmuseum.af.mil/shared/media/photodb/photos/040820-F-1234P-081.jpg&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first generation jet fighters, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-86_Sabre&quot; rel=&quot;noreferrer&quot;&gt;F-86&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15&quot; rel=&quot;noreferrer&quot;&gt;Mig-15&lt;/a&gt; were subsonic and had engines buried into the fuselage to reduce drag. The nose, again carried the cannons (in case of Mig-25, in the lower fuselage).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NdJM1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NdJM1.jpg&quot; alt=&quot;F-86&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F86Sabre.JPG#/media/File:F86Sabre.JPG&quot; rel=&quot;noreferrer&quot;&gt;F86Sabre&lt;/a&gt;&quot; by Kowloonese at the English language Wikipedia is licensed under &lt;a href=&quot;https://creativecommons.org/licenses/by-sa/3.0/us/&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 3.0&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the second generation jet aircraft were the first operational jets to go supersonic. The Mig-21 was designed in response to a Kremlin specification, which called for Mach 2 level speed (at altitude), while carrying a simple radar and option for future air-to-air missiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the jet engines require airflow to be subsonic at entry, the flow has to be decelerated before reaching the engine. Early in the design (from Ye-50-3), Mig decided to use a conical centerbody for this purpose, as it was decided that the aircraft would be single engined with engine in the fuselage (the engine was supposed to be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tumansky_RD-9&quot; rel=&quot;noreferrer&quot;&gt;Mikulin AM-9B&lt;/a&gt;, however, the aircraft ended up using &lt;a href=&quot;https://en.wikipedia.org/wiki/Tumansky_R-11&quot; rel=&quot;noreferrer&quot;&gt;Tumansky R-11&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This nose design decelerated the flow using two oblique shocks and a normal shock, giving improved pressure recovery at high supersonic Mach numbers. The center-body (cone) moved axially according to the Mach number. Also, the center body housed the radar and associated equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first generation Mig 21s only had a range finder, and the intake diameter had a smaller cone. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MRZyN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MRZyN.jpg&quot; alt=&quot;Mig 21 F&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Mig21F13web.jpg#/media/File:Mig21F13web.jpg&quot; rel=&quot;noreferrer&quot;&gt;Mig21F13web&lt;/a&gt;&quot; by Newresid stephanelhernault@yahoo.fr - Own work work vector drawig travail personnel dessinn vectoriel. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;. (Image cropped)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the range finder used in early models of Mig 21.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V2pdA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V2pdA.jpg&quot; alt=&quot;Mig 21 range finder&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MiG-21F-13_radar_Keski-Suomen_ilmailumuseo.JPG#/media/File:MiG-21F-13_radar_Keski-Suomen_ilmailumuseo.JPG&quot; rel=&quot;noreferrer&quot;&gt;MiG-21F-13 radar Keski-Suomen ilmailumuseo&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:MKFI&quot; rel=&quot;noreferrer&quot; title=&quot;User:MKFI&quot;&gt;MKFI&lt;/a&gt; - Own work. Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The photo you've shown are from the later versions (Mig-21 bis from IAF), which had the radars from the &lt;a href=&quot;https://en.wikipedia.org/wiki/RP-21_Sapfir&quot; rel=&quot;noreferrer&quot;&gt;&quot;Sapphire&quot; family&lt;/a&gt;. To fit the radar antenna into the cone, the cone had to be made bigger, therefore the whole front fuselage had to be redesigned, the diameter of intake got more than 200 mm higher, and the cone itself got longer, wider and moved forwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VeDRy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VeDRy.jpg&quot; alt=&quot;Mig 21&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Mig21fishbedHfamilyweb.jpg#/media/File:Mig21fishbedHfamilyweb.jpg&quot; rel=&quot;noreferrer&quot;&gt;Mig21fishbedHfamilyweb&lt;/a&gt;&quot; by Newresid stephanelhernault@yahoo.fr - Own work work vector drawing travail personnel dessin vectoriel. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;. (Image cropped)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following figure shows the enlarged nose cone section housing the radar. Interestingly, the nose cone seems to be made out of (metal tipped) wood to prevent interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9ThWr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9ThWr.jpg&quot; alt=&quot;Mig 21 radar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: toad-design.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of aircraft from that time had conical body inlets, like the British Electric Lightning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FqDGi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FqDGi.jpg&quot; alt=&quot;Lightning&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Lightning.inflight.arp.750pix.jpg#/media/File:Lightning.inflight.arp.750pix.jpg&quot; rel=&quot;noreferrer&quot;&gt;Lightning.inflight.arp.750pix&lt;/a&gt;&quot; by Arpingstone - Own work. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16, on the other hand, has a simple normal shock diffuser. By the time of F-16, the radars had become bigger and more important (AAMs have become the primary combat weapon, replacing guns), and needed more space in the nose. As a result, the inlets of most of the aircraft had moved to the sides/downwards. The following figure shows the AN/APG-68 radar in F-16.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eNF4r.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eNF4r.jpg&quot; alt=&quot;F-16 radar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: defenseindustrydaily.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4452" LastEditDate="2018-03-23T11:31:22.187" LastActivityDate="2018-03-23T11:31:22.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23127" PostTypeId="2" ParentId="23117" CreationDate="2015-11-24T00:10:56.530" Score="35" Body="&lt;p&gt;The design philosophy which led away from the nose intake was to fit a powerful radar to the aircraft, which in turn was a consequence of switching from guns to air-to-air missiles as the primary armament of fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most designs of the late Forties and early Fifties did not consider powerful radars in individual aircraft, but were based on ground radars and radio communication to direct the aircraft towards their opponents. Much of that strategy was an extrapolation from World War II, where large groups of bombers had to be intercepted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Fifties, the advances in electronics and rocket propulsion made air-to-air missiles possible, and gradually the fighter aircraft found themselves in the role of ground stations, scanning a wide space deeply and directing their missiles to individual targets, just like ground radars had done with fighters in the closing years of World War II. Radar range and performance required a large dish in the nose of the aircraft, and the intake had to move to the sides. In parallel, the increased work load for the individual aircraft resulted in two-seater designs, where the radar system was operated by a dedicated back-seater. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the MiG-21 or the BAC Lightning &lt;a href=&quot;https://en.wikipedia.org/wiki/RP-21_Sapfir&quot; rel=&quot;nofollow noreferrer&quot;&gt;did have a radar&lt;/a&gt; in the nose cone, but this was a very small radar for local orientation and not suitable for detecting targets more than 100 km away and directing guided weapons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to why the intake was shaped as it is, please read &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=6%7C0.1451#9222&quot;&gt;this answer here on Stack Exchange&lt;/a&gt; on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13096/what-are-the-merits-of-an-inlet-cone-spike-centerbody-vs-a-2d-inlet/13109?s=1%7C0.0732#13109&quot;&gt;design of supersonic intakes&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/imjmI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/imjmI.jpg&quot; alt=&quot;North American F-100 Super Sabre&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;North American F-100 Super Sabre (picture &lt;a href=&quot;http://North%20American%20F-100%20Super%20Sabre&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Just like the MiG-21, this was designed to be led from the ground and engage the enemy in visual conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XlctB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XlctB.jpg&quot; alt=&quot;Convair F-106 Delta Dart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convair &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F-106_Delta_Dart&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-106 Delta Dart&lt;/a&gt; (picture &lt;a href=&quot;http://www.howitflies.com/files/photos/wikiexport/5/55/F-106A_Chase_Dart.JPEG&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). This was the first fighter designed to use missiles as a primary weapon. Its radar system was extremely complex, combining on-board with ground assets, for all-weather operation using missiles over long distance, including a nuclear-tipped version for use against big bomber formations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GTxG3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GTxG3.jpg&quot; alt=&quot;MiG Ye-8&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just so you don't think that Mikoyan would not try to integrate bigger radars (picture &lt;a href=&quot;http://www.cavok.com.br/blog/wp-content/uploads/2014/09/YE_8_1-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;): The &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_Ye-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ye-8&lt;/a&gt; prototype changed the intake to an F-16 style belly intake to make room in the nose for a Sapfir 21 radar, which enabled the MiG-21 to engage targets in all weather conditions and at night. First flight was in April of 1962, but no production followed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ldkNg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ldkNg.jpg&quot; alt=&quot;McDonnell-Douglas F-4 Phantom II&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;McDonnell-Douglas F-4 Phantom II (picture &lt;a href=&quot;http://images.forwallpaper.com/files/thumbs/preview/30/305999__mcdonnell-douglas-f4-phantom-ii_p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Just a decade after the F-100, the nose was designed around a &lt;a href=&quot;http://wiki.scramble.nl/index.php/Westinghouse_AN/APQ-72&quot; rel=&quot;nofollow noreferrer&quot;&gt;81cm radar dish&lt;/a&gt; and the aircraft gained a dedicated radar operator to engage enemy aircraft without ground support and in all weather conditions. Now, it can be argued that its side intakes were a consequence of using two engines, but the F-106 used a single engine and still had similar side intakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2Ekae.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Ekae.jpg&quot; alt=&quot;Radar of the Phantom II&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar of the Phantom II (picture &lt;a href=&quot;http://www.fiddlersgreen.net/aircraft/McDonnell-Phantom/IMAGES/McDonnell-Douglas-F4-Phantom-Radar.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Advances in computer control reduce the workload and the size of the aircraft, so the F-16 can be operated by a single person and still carries a radar powerful enough for independent all-weather operation.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-08-29T23:06:48.813" LastActivityDate="2017-08-29T23:06:48.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23128" PostTypeId="2" ParentId="23125" CreationDate="2015-11-24T00:59:43.980" Score="6" Body="&lt;p&gt;For best results, put good flaps on the wing and forget using a winglet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you insist on bending the wing up at its end, just continue with the tip airfoil and select the incidence such that your circulation distribution over the wing and winglet will become elliptical when you plot it in a straight line. The small size of your airplane implies that you will not need to unload the tips to reduce root bending moment.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-11-24T00:59:43.980" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23129" PostTypeId="1" AcceptedAnswerId="23130" CreationDate="2015-11-24T05:55:46.733" Score="0" ViewCount="408" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15955/how-much-time-it-will-take-a-b787-to-fuel-completely-when-empty&quot;&gt;Here is the question&lt;/a&gt; I was looking for (it didn't answer my question though), but this is specific to Boeing 787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any regulation to carry certain amount (may be %) of fuel aircraft should carry when its flight plan is prepared?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: We had argument that aircraft should carry 150% of fuel of it's planned travel, then someone bought argument of hijacking planes and said that 15 to 30 minutes of extra travel time fuel they have to carry.&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-11-24T07:35:14.973" Title="How much fuel aircraft should carry to complete flight plan?" Tags="&lt;flight-planning&gt;&lt;fuel&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-11-24T08:08:00.703" ContentLicense="CC BY-SA 3.0" />
  <row Id="23130" PostTypeId="2" ParentId="23129" CreationDate="2015-11-24T06:19:44.167" Score="3" Body="&lt;p&gt;This may vary elsewhere in the world but according to the &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGFAR.NSF/0/1cc5b5dad63e4806852566ef006dd813!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA FAR Sec. 121.639&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Fuel supply: All domestic operations.&lt;/p&gt;&#xA;&lt;p&gt;No person may dispatch or take off an airplane unless it has enough&#xA;fuel--&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(a) To fly to the airport to which it is dispatched;&lt;/li&gt;&#xA;&lt;li&gt;(b) Thereafter, to fly to and land at the most distant alternate airport&#xA;(where required) for the airport to which dispatched; and&lt;/li&gt;&#xA;&lt;li&gt;(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption&#xA;or, for certificate holders who are authorized to conduct day VFR&#xA;operations in their operations specifications and who are operating&#xA;nontransport category airplanes type certificated after December 31,&#xA;1964, to fly for 30 minutes at normal cruising fuel consumption for&#xA;day VFR operations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-24T06:19:44.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23131" PostTypeId="1" AcceptedAnswerId="23139" CreationDate="2015-11-24T07:10:03.047" Score="3" ViewCount="1025" Body="&lt;p&gt;Is there any particular reason for having the ground represented by brown on an artificial horizon or PFD?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blue represents sky, brown represents earth, which will be used for easily identifying the aircraft attitude (along with line of origin). Using blue to represent the sky makes conventional sense. But why is brown used? Is there any scientific reason for using brown instead of another color?&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="167" LastEditDate="2015-11-25T00:09:57.693" LastActivityDate="2015-11-25T00:09:57.693" Title="Why was brown chosen to represent the ground side of an attitude indicator?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;&lt;display&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23132" PostTypeId="2" ParentId="23131" CreationDate="2015-11-24T07:32:53.357" Score="8" Body="&lt;p&gt;If they used green (like grass) you would have asked the same: &quot;Why didn't the use brown (like soil)?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Blue - brown is easier to distinguish, than blue - green, blue - red or another color-combination you can think of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Contrast:&lt;/strong&gt;&lt;br&gt;&#xA;The use of this two colors can be explained by the high contrast from blue to brown. The pilot can find out with one quick glance at the PFD how the aircraft is positioned in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Natural colors - pilot instantly knows what it means:&lt;/strong&gt;&lt;br&gt;&#xA;Because those are &quot;natural&quot; colors, the pilot instantly knows that blue means sky and brown means ground. He doesn't have to process the color information in his head just to find out what it means. This would take much longer.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="65" LastEditDate="2015-11-24T21:29:34.907" LastActivityDate="2015-11-24T21:29:34.907" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23133" PostTypeId="1" AcceptedAnswerId="23134" CreationDate="2015-11-24T10:46:23.920" Score="1" ViewCount="611" Body="&lt;p&gt;I notice the atitude indicator displayed in the PFD is either squared-shape or truncated-circle-shaped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example of the square shape is the B747-400, It looks like a square whose corner are a bit rounded:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hXZlP.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hXZlP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;SUP&gt;(Source: &lt;a href=&quot;https://www.airliners.net/photo/South-African-Airways/Boeing-747-444/230868&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/SUP&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example of the circle-shaped is the SAAB2000 or the A340:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yqkge.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yqkge.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;SUP&gt;(Sources: &lt;a href=&quot;https://www.airliners.net/photo/Crossair/Saab-2000/287067&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt; and &lt;a href=&quot;https://www.airliners.net/photo/Swiss-International-Air-Lines/Airbus-A340-313/1636675&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/SUP&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They look like a circle whose both right and left sides are truncated to display rules (speed and altitude).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In either case, the information displayed are the same (pitch, bank angle, perhaps flight director,...) and are displayed in a very similar manner (including the colors). Those 2 designs exists for years, so there may not be advantages of one over the other.  Why one is preferred over the other for some manufacturer, and the other one for other manufacturer? What criteria are taken into account when choosing this shape?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="14897" LastEditDate="2019-02-10T22:26:38.587" LastActivityDate="2019-02-10T22:27:29.730" Title="What dictates the shape of the attitude indicator display on the PFD?" Tags="&lt;aircraft-design&gt;&lt;avionics&gt;&lt;flight-instruments&gt;&lt;glass-cockpit&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="23134" PostTypeId="2" ParentId="23133" CreationDate="2015-11-24T12:22:18.547" Score="4" Body="&lt;p&gt;A circle makes sense because a physical attitude indicator is round. (A physical one has to be round because it consists of a ball moving behind a window.) It makes the screen display look more like the instrument it replaces, which is good for recognition and familiarity, and makes it easier to judge things like bank angles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A rectangle makes sense because it has to fit on a rectangular screen. You can tile rectangular instruments/displays on a screen efficiently, with no wasted space between them, as your example shows with the tapes. Rounding the corners delineates the edges of the display better than just having abutting rectangles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The full process by which physical cockpit instruments and glass-cockpit displays are designed and laid out is too long to explain here. The main focus is on making it hard to make mistakes, and after that to make it quick to see the most important information. To support this, each instrument has to be easy to identify and to read correctly. Despite the shape difference, the two designs look very similar. Even if you've never flown any of these aircraft before, you'd immediately recognise it as an attitude indicator, and you wouldn't confuse it with a different instrument.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-11-24T12:22:18.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23135" PostTypeId="1" CreationDate="2015-11-24T13:34:59.787" Score="11" ViewCount="16295" Body="&lt;p&gt;On fire events, some aircraft have a complex system, usually called a Fire Suppression System.&#xA;Where are they located? Do they work automatically, or it is necessary for the crew to activate them?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="-1" LastEditDate="2015-11-24T20:02:01.087" LastActivityDate="2015-11-24T20:02:01.087" Title="How does a fire suppression system work?" Tags="&lt;fire&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23136" PostTypeId="2" ParentId="23135" CreationDate="2015-11-24T14:24:13.830" Score="5" Body="&lt;p&gt;In commercial airliners, there are usually two places where fire suppression systems are installed: the cargo compartment and the engines. Take the Boeing 777 for example, it has fire detection and extinguishing systems in the APU (which is technically an engine as well), cargo compartments, engines and lavatories; the crew rest compartments and main gear wheel wells come with fire detection but no extinguishing system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fire detection consists of two sensors. To prevent false alarms, both sensors must sense the presence of smoke for the alarm to be sound. The sensors has self fault-detection capability. One of the items on the pre-flight checklist is to activate the test circuits and see if the fire alarm sounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fire suppression systems work by spraying a chemical agent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When smoke is detected, an aural alarm is sound in the cockpit, along with red lights which indicate where is the fire. A message will also be shown in the flight computer screen (if the cockpit has one).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SSKkf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SSKkf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most systems, the pilots have to &lt;a href=&quot;https://aviation.stackexchange.com/questions/2126/why-dont-aeroplanes-automatically-put-out-engine-fires&quot;&gt;manually pull the handles to activate fire suppression&lt;/a&gt;. Take the engine fire extinguishing system in a Boeing 777 for example, there are two engine fire extinguisher bottles. Either or both bottles can be discharged into either engine. It is up to the pilots to follow the emergency procedures, or make a judgment call if they think the pre-established procedure is not the best course of action in a given situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lavatory fire extinguisher, on the other hand, is automatic.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-11-24T14:32:59.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23137" PostTypeId="2" ParentId="23135" CreationDate="2015-11-24T14:27:04.930" Score="12" Body="&lt;p&gt;The fire suppression system in an aircraft uses both passive and active systems to reduce and eliminate fires. Passive methods include the use of noncombustible materials, separation by routing, compartmentalization (use of firewalls), isolation, proper ventilation and drainage. The active methods include fire detection and extinguishing systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fire extinguishing system in the aircraft consists of a number of components (excluding the fire detection system), which includes,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Portable (handheld) fire extinguishers in cockpit and cabin,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fire extinguisher bottles for engines and APU&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cargo hold fire extinguisher systems and&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fire extinguishers for toilet waste bins.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All the transport aircraft are required to carry a minimum number of portable fire extinguishers depending on the number of passengers carried. The following table gives the minimum number of portable fire extinguishers to be carried in transport aircraft (the cockpit should have a minimum of one).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JgwJx.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JgwJx.png&quot; alt=&quot;Number of fire extinguishers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Table from FAA document &lt;em&gt;Fire Protection Systems&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of cabin (or cockpit) fire, the portable fire extinguishers (usually, $CO_{2}$ extinguishers are not used) are used by the crew to extinguish the fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines and APUs have their own fire extinguishing systems, which have a liquid halogenated extinguishing agent and pressurized gas stored in fixed (typically steel) fire extinguisher containers, which are discharged on pilot command.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines have their own fire extinguishing systems, which usually have a pair of fire extinguishing bottles (or a pair for each engine), which supply extinguishing agent (Halon 1301 or Hydrofluorocompounds) to the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FagMS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FagMS.jpg&quot; alt=&quot;Engine fire extinguishing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Boeing Aero magazine- &lt;em&gt;Fire Protection: Engines and Auxiliary Power Units&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fire detection system from each engine displays the status in the cockpit, which warns of any engine fire. In case the pilot pulls the fire handle, the fuel flow to the engine is shut off and an explosive cartridge is fired in the fire extinguishing bottle, releasing the agent into the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4wbev.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4wbev.png&quot; alt=&quot;Fire extinguisher engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from FAA document &lt;em&gt;Fire Protection Systems&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The APU fire suppression system is similar to the engine fire suppression system, though only a single fire extinguisher bottle is used. Again, the fire extinguisher operation is commanded by the cockpit crew and results in the shutting down of the APU and the source of air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/34RBA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/34RBA.jpg&quot; alt=&quot;APU fire extinguisher&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Boeing Aero magazine- &lt;em&gt;Fire Protection: Engines and Auxiliary Power Units&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ground, the APU fire extinguishing system can operate automatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cargo hold fire extinguishing system is similar to the above, where the crew can activate the fire extinguishing system if the smoke detectors in the cargo hold activates the warning lights in cabin. The extinguishing system is of two types- a dump system that releases the extinguishing agent directly&#xA;when the cargo fire discharge switch is activated or a metered system, where metered bottles discharge slowly which keeps the correct concentration of extinguishing agent in the cargo compartment to keep the fire extinguished for 180 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tN9Ww.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tN9Ww.png&quot; alt=&quot;Cargo hold fire suppression&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Table from FAA document &lt;em&gt;Fire Protection Systems&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The toilet waste bin is the only place in the aircraft with an automatic fire extinguishing system (in addition to ashtrays), where the heat sensors (not smoke detectors) trigger fire extinguishers.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Some aircraft have On Board Inert Gas Generating System (OBIGGS), which is used to 'inert' the fuel tank using nitrogen (usually generated by membrane based gas separation). &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-24T14:27:04.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23138" PostTypeId="1" AcceptedAnswerId="23143" CreationDate="2015-11-24T14:43:17.577" Score="27" ViewCount="14114" Body="&lt;p&gt;As I have never flown inside a cockpit, but only played with simulators I find that the dashboard takes most of the field of view(or am I wrong?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what actually can pilots see given good weather conditions, especially during critical parts of a flight, like take-offs and landings ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm generally interested in big airliners. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. I am not asking if they could takeoff/land without visual contact.&lt;/p&gt;&#xA;" OwnerUserId="11787" LastEditorUserId="11787" LastEditDate="2015-11-24T14:50:41.270" LastActivityDate="2015-11-26T07:43:27.990" Title="What do pilots actually see through the windows?" Tags="&lt;airliner&gt;&lt;pilots&gt;&lt;cockpit&gt;" AnswerCount="6" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23139" PostTypeId="2" ParentId="23131" CreationDate="2015-11-24T14:50:02.033" Score="9" Body="&lt;p&gt;The answer to the specific question of &quot;&lt;em&gt;why PFD's (glass cockpits) use this standard&lt;/em&gt;&quot; is because their old style gauge cockpits used it before them. The glass cockpits of today are made to be similar to the older gauges so as to avoid confusion in their operation when moving from one type of aircraft to the other. This has been shown to be an issue in the past in the difference between American and Russian attitude indicators as such instrument operation strives to be at least somewhat uniform. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now as for the more general question &quot;&lt;em&gt;why are attitude indicators Blue/Brown?&lt;/em&gt;&quot; there are a few reasons. First off &lt;a href=&quot;http://www.color-blindness.com/2007/05/18/mixing-up-blue-and-green/&quot; rel=&quot;nofollow noreferrer&quot;&gt;some types of color blindness cause issues with the blue/green mix&lt;/a&gt; making it a combination to avoid (&lt;a href=&quot;https://www.leftseat.com/baggish.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;some info on color blind flying&lt;/a&gt;). Second, and perhaps as important is that blue and brown sit basically on opposite sides of the color wheel making them very contrasty while blue and green sit right next to each other on the wheel. This ensures accurate viewing in most lighting situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also other attitude indicators like those commonly used in military aircraft which have had different colors &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o7ZgR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o7ZgR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://aviation.watergeek.eu/f4j-panel.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The oldest examples are completely void of any color (you can see why they introduced color) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oRWch.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oRWch.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://aviation.watergeek.eu/aviation_sales.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth some modern flight displays now include terrain data and are capable of showing many other colors to outline it as can be seen here on this Garmin unit &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZZfpB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZZfpB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://txtopaviation.com/synthetic-vision-technology/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-24T14:50:02.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23140" PostTypeId="2" ParentId="23138" CreationDate="2015-11-24T14:50:36.587" Score="18" Body="&lt;p&gt;This really depends on the type of aircraft and the seating position of the pilot. In smaller aircraft, you will have a good view of the area around you, depending on the canopy. In larger aircraft, the instrument panel and cockpit design can restrict your outside view a bit more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you will find two pictures taken from the cockpit of a Super Dimona HK36, used for VFR general aviation flights. Both are approximately at eye level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G0Xc6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G0Xc6.jpg&quot; alt=&quot;Dimona Cockpit 1&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: Own Work - SentryRaven)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MAbTs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MAbTs.jpg&quot; alt=&quot;Dimona Cockpit 2&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Source: Own Work - SentryRaven)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-11-24T14:50:36.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23141" PostTypeId="2" ParentId="23138" CreationDate="2015-11-24T15:16:12.113" Score="18" Body="&lt;p&gt;In a document A319/A320/A321 Flight Deck and Systems Briefing for Pilots (can be found in many places on the net, e.g. &lt;a href=&quot;http://www.slideshare.net/FernandoNobre1/a319-320-321-flight-deck-and-systems-briefing-for-pilots&quot; rel=&quot;nofollow noreferrer&quot;&gt;on slideshare as presentation&lt;/a&gt;), or page 16 Airbus shows following diagram of visibility from cockpit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/PEXo4.jpg&quot; alt=&quot;A319/A320/A321 flight deck - pilot&amp;#39;s field of view&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;17 or 20 degrees below horizon is not that bad. It is probably a little less than you see from a typical &lt;em&gt;car&lt;/em&gt;, but not by much (of course since the pilots are sitting much higher, the nearest point on pavement is correspondingly further away).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that whether the above is actually true depends on how the pilot adjusts their seat. The recommended height for eyes is marked on the post between the forward windows.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-11-24T19:26:47.727" LastActivityDate="2015-11-24T19:26:47.727" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23142" PostTypeId="2" ParentId="23138" CreationDate="2015-11-24T15:30:59.397" Score="6" Body="&lt;p&gt;I'll illustrate some aspects which I think even the best flight simulation today cannot compensate:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Peripheral vision&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Telling distances and relative positions is much easier. For example, you can tell a certain building is 1000 feet away. When you are landing, you can take a quick glance to either side of the runway and judge whether it is time to flare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sitting in the cockpit of a 747 feels rather like standing on top of a 3-story building. The best part is, this building moves! It's truly amazing.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Detailed view&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I know this sounds obvious, but I have to put it as number two. Even when you are on final, you can see the little cars with people moving around the ramp and terminal. The cockpit glass is just like the windshield in your car; if you can see something directly, you will see it in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also see the small cracks in the windshield, especially when sunlight is directly shinning at it. This is a natural property of the material used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're flying a single-engine propeller plane, your view will be slightly obstructed by the spinning propeller.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Other planes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Spotting other planes in a real cockpit is a bit tricky. If the plane is below you, and you're flying over residential areas with lot of houses, it can be hard to spot.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-11-24T15:30:59.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23143" PostTypeId="2" ParentId="23138" CreationDate="2015-11-24T16:06:21.567" Score="13" Body="&lt;p&gt;In general, the pilots are required to have good visibility to execute any maneuvers during normal operation of the aircraft. According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.11#se14.1.25_1773&quot; rel=&quot;noreferrer&quot;&gt;Federal Aviation Regulations Part 225, Section 773- Pilot Compartment View&lt;/a&gt;, during non-precipitation conditions,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Each pilot compartment must be arranged to give the pilots a sufficiently extensive, clear, and undistorted view, to enable them to safely perform any maneuvers within the operating limitations of the airplane, including taxiing takeoff, approach, and landing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA advisory Circular 25.773-1 Pilot Compartment View design considerations gives certain guidelines for ensuring pilot visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I5ga0.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I5ga0.png&quot; alt=&quot;Pilot view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot compartment view from FAA AC 25.773-1 &lt;em&gt;Pilot Compartment View design considerations&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The figure shows a pilot compartment view for optimum collision avoidance&#xA;when seated in the left (port) seat. For the starboard side, all left/right dimensions are reversed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, the aircrafts offer better visibility compared to the guidelines. For example, the A330's visibility (from &lt;a href=&quot;http://www.slideshare.net/FernandoNobre1/a330-flight-deck-and-systems-briefing-for-pilots&quot; rel=&quot;noreferrer&quot;&gt;Flight deck and system's briefing&lt;/a&gt;) is given here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ubWW5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ubWW5.jpg&quot; alt=&quot;A330 pilot view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.slideshare.net/FernandoNobre1/a330-flight-deck-and-systems-briefing-for-pilots&quot; rel=&quot;noreferrer&quot;&gt;A 330 Flight deck and system's briefing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual visibility of the pilots will vary according to the seat position For example, the following figure shows the variation in pilot visibility in Boeing 727 when seat position is adjusted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Fan0p.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fan0p.png&quot; alt=&quot;Boeing 727 Visibility&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Airplane Design- Layout Design of Cockpit, Fuselage, Wing and Empennage&lt;/em&gt; by Jan Roskam&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the pilots can see things which is normally not visible though the windows through cameras mounted on the outside, like on top of vertical tail in A380.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-24T16:06:21.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23144" PostTypeId="1" CreationDate="2015-11-24T17:06:38.323" Score="7" ViewCount="819" Body="&lt;p&gt;Some aircraft are equiped with auto landing to assist on zero visibility and ceiling land. Actually, how does this system work?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="753" LastEditDate="2015-11-25T15:57:40.097" LastActivityDate="2015-11-25T15:57:40.097" Title="How does auto landing work?" Tags="&lt;safety&gt;&lt;landing&gt;&lt;autoland&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23146" PostTypeId="1" AcceptedAnswerId="23147" CreationDate="2015-11-24T17:39:11.367" Score="18" ViewCount="3730" Body="&lt;p&gt;During the world wars, various barrage balloons were used to protect targets from low-flying aircraft or similar threats (e.g. V-1 flying bombs), in particular by Britain.&lt;br&gt;&#xA;What lifting gas was used for such barrage balloons – the highly flammable hydrogen or the rare and expensive helium?&lt;/p&gt;&#xA;" OwnerDisplayName="user5604" LastEditorUserId="3386" LastEditDate="2018-04-22T04:33:14.817" LastActivityDate="2018-04-29T10:00:44.247" Title="What lifting gas was used for barrage balloons during the world wars?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;balloon&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23147" PostTypeId="2" ParentId="23146" CreationDate="2015-11-24T18:21:22.860" Score="16" Body="&lt;p&gt;According to a BBC article &lt;a href=&quot;http://www.bbc.co.uk/history/ww2peopleswar/stories/83/a4551383.shtml&quot;&gt;here&lt;/a&gt;, hydrogen was used, not helium.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastActivityDate="2015-11-24T18:21:22.860" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23148" PostTypeId="2" ParentId="23144" CreationDate="2015-11-24T19:42:36.397" Score="2" Body="&lt;p&gt;Autoland is an autopilot feature which allows the autopilot to control the aircraft all the way to touch-down and even a bit further.&lt;br&gt;&#xA;Basic idea is that the autopilot is accurate enough to keep the aircraft on the correct approach path. This is achieved by (on top of really good software engineering) with at least 2 autopilot/flight director calculators. One of the calculators is the one in control, anfd the other one is monitoring the first one. In case of disagreement between the systems, a fault is announced and the approach must be aborted (fail-passive system).&lt;br&gt;&#xA;There are also fail-active systems that require 3 autopilot channels. These are capable of continuing the approach even if one system gets faulted.&lt;br&gt;&#xA;Some systems have a roll-out guidance to keep the aircraft aligned on the runway centerline after touch-down during braking.&lt;br&gt;&#xA;Functionality is the same as with autopilot. The calculator gives commands to the control surfaces and thus steers the aircraft. In addition a radio altimeter gives accurate altitude information to enble flare and thrust reduction.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2015-11-24T19:42:36.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23149" PostTypeId="2" ParentId="23146" CreationDate="2015-11-24T20:50:55.423" Score="16" Body="&lt;p&gt;Hydrogen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helium was scarce or not available at all. The only substantial source was in the United States, which had a &lt;a href=&quot;http://www.nature.com/nature/journal/v145/n3668/abs/145257c0.html&quot; rel=&quot;noreferrer&quot;&gt;capacity of 24 million cubic feet (680,000 m³) in 1940&lt;/a&gt;. Its commercial and military needs of that time were just a quarter of this amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at &lt;a href=&quot;http://minerals.usgs.gov/minerals/pubs/historical-statistics/ds140-heliu.pdf&quot; rel=&quot;noreferrer&quot;&gt;this statistics of word helium production&lt;/a&gt;, you will notice that only from 1963 on did total world production of helium differ from the amount produced in the US. You will also note that production shot up from 45 metric tons in 1940 to 608 metric tons (3.6 million m³) in 1944, which is most likely to cover the increased need for war. Also, exports only started in the 1960s. Sadly, the MYB statistics have no export data from earlier years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This lets me conclude that only hydrogen was available in all other countries throughout the war, and only the US used helium. The US production was needed to fill anti-submarine observation blimps. One &lt;a href=&quot;https://en.wikipedia.org/wiki/K-class_blimp&quot; rel=&quot;noreferrer&quot;&gt;K-class blimp&lt;/a&gt; had a hull volume of 404,000 to 425,000 cubic feet (11,480 to 12,035 m³) and needed to be topped up every few weeks. A total of 134 of that type were built, and just filling them once would already had consumed half of the helium produced in 1944, the most productive year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hVBfL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hVBfL.jpg&quot; alt=&quot;US Navy blimp in WW II&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;US Navy K-class blimp in WW II (picture &lt;a href=&quot;http://www.bathroomreader.com/2015/08/trivia-facts-goodyear-blimp/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-11-24T20:50:55.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23151" PostTypeId="1" AcceptedAnswerId="23154" CreationDate="2015-11-25T05:49:35.340" Score="16" ViewCount="27377" Body="&lt;p&gt;I've heard that the engines on a commercial air transports are typically mounted with 2 or 3 bolts. Is this true? If so, how big are these bolts and what are they made of?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm optimizing a bolted joint for my FEA class, and I'd like to check my results against reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: The Factor of Safety on such a bolt would be nice too!&lt;/p&gt;&#xA;" OwnerUserId="4432" LastActivityDate="2020-01-09T20:17:09.083" Title="How are engines mounted onto wings?" Tags="&lt;safety&gt;&lt;engine&gt;&lt;aircraft-structures&gt;&lt;aerospace-materials&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23152" PostTypeId="1" AcceptedAnswerId="23153" CreationDate="2015-11-25T08:38:16.143" Score="7" ViewCount="1607" Body="&lt;p&gt;There are reports in the media saying Turkey shot down a Russian military aircraft after ignoring several warnings and after they entered Turkish airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which &quot;warnings&quot; are these? Are they standardized somehow?&lt;/p&gt;&#xA;" OwnerUserId="424" LastActivityDate="2015-11-25T08:51:24.217" Title="Which &quot;warnings&quot; are issued when a military aircraft is going to enter foreign airspace?" Tags="&lt;military&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23153" PostTypeId="2" ParentId="23152" CreationDate="2015-11-25T08:51:24.217" Score="8" Body="&lt;p&gt;This depends on the rules of engagement for a country and how the intercepting aircraft are instructed to act. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Radio Contact&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The intercepting aircraft will try to establish radio contact on the &lt;a href=&quot;https://en.wikipedia.org/wiki/International_distress_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;distress frequencies&lt;/a&gt; available. 121.500 MHz or for NATO aircraft 243.000 MHz. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Visual Contact&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless there is an imminent threat, the intercepting aircraft can position next to the intruding aircraft and establish visual contact with the pilots. There is also standardized procedures, such as the infamous rocking of wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2qQ8L.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2qQ8L.png&quot; alt=&quot;Intercept&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;http://www.cfinotebook.net/notebook/flight-hazards-and-safety/intercept-procedures.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.cfinotebook.net&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flares&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unless at high altitude, ground based units can shoot flares to attract attention and inform aircraft that they are entering prohibited or restricted airspace.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-11-25T08:51:24.217" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="23154" PostTypeId="2" ParentId="23151" CreationDate="2015-11-25T10:31:04.880" Score="16" Body="&lt;p&gt;On Sunday 4 October 1992, &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19921004-2&quot; rel=&quot;noreferrer&quot;&gt;El Al Flight 1862&lt;/a&gt; crashed into a suburb of Amsterdam after the right inboard engine separated from the wing and took part of the wing and the right outboard engine with it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The separation was caused by fatigue fracture of the fuse-pins that connect the engine to the aircraft. The engines of the Boeing 747-200 are joined to the wing by four fuse-pins. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://aviation-safety.net/get.php?http://asndata.aviation-safety.net/reports/Netherlands/19921004-2_B742_4X-AXG.pdf&quot; rel=&quot;noreferrer&quot;&gt;investigation report&lt;/a&gt; you can find detailed information about the construction that mounts the engine to the wing. Especially sections 1.6.3, 1.6.4 and 1.16 are of interest to you, although I recommend reading the entire report if you have the time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YXboR.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YXboR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Raad voor de Luchtvaart, document AAR 92-11&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XHCF1.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XHCF1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Raad voor de Luchtvaart, document AAR 92-11&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-11-25T11:14:42.130" LastActivityDate="2015-11-25T11:14:42.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23155" PostTypeId="2" ParentId="23151" CreationDate="2015-11-25T11:11:53.777" Score="8" Body="&lt;p&gt;You're correct that the engines are mounted to the aircraft using only a few bolts. Usually, the engines are mounted on the wing at three points (usually two forward and one aft) with shear (or fuse) pins, with one or two bolts at each point. The DC-10, for example 6 (later 8 pins), while the 747-200 has 6.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5Gte6.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Gte6.png&quot; alt=&quot;DC-10 engine mount&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:DC-10_engine-pylon.svg#/media/File:DC-10_engine-pylon.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-10 engine-pylon&lt;/a&gt;&quot;. Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following figure shows the engine mounting in A350 XWB, in which the aft mounting point and the load struts can be clearly seen (the first box), in which the engine is attached with two bolts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/joRiG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/joRiG.jpg&quot; alt=&quot;A350 engine mount&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/print.main?id=5751928&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shear pins have a complex cross section and are designed in such a way that it shears off in case of an impact. For example, the following figure shows the design of (three different) shear pins used in Boeing 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V8sD6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V8sD6.jpg&quot; alt=&quot;B747 fuse pin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=1&amp;amp;LLID=38&amp;amp;LLTypeID=2#null&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA overview of accident involving Israeli Airlines FLT 1862&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shear pin bolt size depends on the particular aircraft and the engine combination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for safety factor, they are designed to break off in case the (shear) loads on them cross a certain threshold. The engine-to-wing supporting structure is designed to release the engine when extreme forces are encountered, in order to prevent any structural damage to the wing that may impair the aircraft's ability to fly. As such, their design philosophy is different from safe load design and varies from aircraft to aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://blog.flightstory.net/421/investigationreport-nationwide-737-200-accident-at-cpl/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Incidents have happened&lt;/a&gt; where the engine has separated from the aircraft due to the large forces experienced.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-11-25T20:19:07.050" LastActivityDate="2015-11-25T20:19:07.050" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23156" PostTypeId="2" ParentId="23117" CreationDate="2015-11-25T14:30:23.737" Score="9" Body="&lt;p&gt;To be extremely simple without going into too much technical design theroy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It allows the engine to breath at high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice that in front of a high speed fan or a cooler it will be extremely difficult for you to breath, try putting your head out of the car and breath when travelling at 60mph , it will be much more difficult to breath compared to doing the same while travelling at 20mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its the same principle, since you cannot reduce the speed of the aircraft to allow it to breath, the cone acts as a hand in front of your nose at 60mph which will allow you to breath and maintain the speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It disrupts the direct flow of the air into the engine and reduces the speed of the air to sub sonic levels which the engine can process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fun Fact: The design is already present in nature and was lifted off of the peregrine Falcon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/4T4B3.jpg&quot; alt=&quot;peregrine Falcon&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Head shot by Keven Law protected under CC BY-SA 2.0]&lt;/p&gt;&#xA;" OwnerUserId="11615" LastEditorUserId="1875" LastEditDate="2015-11-25T23:12:59.070" LastActivityDate="2015-11-25T23:12:59.070" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23157" PostTypeId="1" CreationDate="2015-11-25T19:00:47.250" Score="-2" ViewCount="638" Body="&lt;p&gt;I know that ejection seats are good to help save pilots' lives, but they're not foolproof either and the design hasn't changed for decades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why don't pilots wear a squirrel suit or wingsuit so that they can fly away to open the parachute far from the enemy?&lt;/p&gt;&#xA;" OwnerUserId="12415" LastEditorUserId="62" LastEditDate="2015-11-25T22:16:52.163" LastActivityDate="2016-02-13T03:09:04.733" Title="Could wingsuits replace or supplement ejection seats?" Tags="&lt;ejection-seat&gt;" AnswerCount="4" CommentCount="0" ClosedDate="2016-02-13T14:28:41.737" ContentLicense="CC BY-SA 3.0" />
  <row Id="23158" PostTypeId="2" ParentId="23157" CreationDate="2015-11-25T19:12:54.797" Score="4" Body="&lt;p&gt;I assume you mean a wingsuit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea behind ejection seats is that in a fighter jet, you are seating on tons of explosive materials (Jet fuel, munitions, ...).&#xA;You want to get away from that as quickly as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A wingsuit would be very inconfortable to wear in the cockpit during nominal flight, and it would be almost impossible to get off of the plane at high speed without ramming it, probably killing yourself in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;=&gt; Ejection seat is the only solution for high speed/potentially explosive bail out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sail plane on the other hand don't explode and fly relatively slowly so jumping away with a parachute is doable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might ask why not using ejection seat THEN wingsuit &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be impractical as it would only gives you very limited range (strikes can be done hundreds or thousands of kilometers inside hostile zone.&#xA;And the ejection seat is so brutal that you would probably not be able to maneuver it properly after the shock of the ejection.&lt;/p&gt;&#xA;" OwnerUserId="4105" LastActivityDate="2015-11-25T19:12:54.797" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23159" PostTypeId="2" ParentId="23111" CreationDate="2015-11-25T19:54:21.273" Score="2" Body="&lt;p&gt;An Aeronautical License issued by the &lt;a href=&quot;http://www.acma.gov.au/&quot; rel=&quot;nofollow&quot;&gt;Australian Communications and Media Authority&lt;/a&gt; (ACMA) is required in order to operate a handheld aviation-band VHF transceiver in Australia.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aeronautical licence is issued to authorise a station that:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;is not fixed to an aircraft; &lt;/li&gt;&#xA;  &lt;li&gt;is operated on aeronautical frequencies;&lt;/li&gt;&#xA;  &lt;li&gt;is operated for purposes relating to the operation of an aircraft, or&#xA;  airport or aerodrome operations; and &lt;/li&gt;&#xA;  &lt;li&gt;in relation to an aircraft&#xA;  includes a mobile station operated on board the aircraft or on the&#xA;  ground in communication with aircraft. &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;An aeronautical licence is&#xA;  necessary to authorise the operation of stations providing:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;air traffic control services; &lt;/li&gt;&#xA;  &lt;li&gt;aerodrome radio information services;&lt;/li&gt;&#xA;  &lt;li&gt;private company radiocommunications; and &lt;/li&gt;&#xA;  &lt;li&gt;other airport or aerodrome&#xA;  services.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Reference: &lt;a href=&quot;http://www.acma.gov.au/theACMA/aeronautical-licences-guidelines&quot; rel=&quot;nofollow&quot;&gt;ACMA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Australian-based &lt;a href=&quot;http://www.recreationalflying.com/tutorials/comms/licence.html&quot; rel=&quot;nofollow&quot;&gt;recreationalflying.com&lt;/a&gt; tutorial website may also provide more useful information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note: This applies for a transceiver -- i.e. transmit &amp;amp; receive -- rules may be different for receive-only).&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2016-07-06T21:42:34.140" LastActivityDate="2016-07-06T21:42:34.140" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23160" PostTypeId="2" ParentId="23157" CreationDate="2015-11-25T20:09:59.097" Score="7" Body="&lt;p&gt;A wing suit has a glide ratio of only 2.5:1 in ideal conditions. That's no more than 20kms of horizontal flight, which means that you're not likely to reach any safe place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ejecting from a fighter jet is not an ideal condition. The odds of being knocked out be the blast, canopy or whatever made you abandon your aircraft in the first place are very real. Furthermore, ejection at very low altitude is not unheard of. This is why the chute is not deployed manually, and why the chute is not controllable like skydiving 'mattresses'. You don't want to tumble out of control! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, you're carrying a small raft and some emergency supplies, all of which would not improve your glide slope. The jet is really the best method of reaching a safe place; ejecting is only there to reach the ground with most limbs attached if your supersonic get-the-hell-out-of-here vehicle is compromised. &lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2015-11-25T20:09:59.097" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23161" PostTypeId="2" ParentId="887" CreationDate="2015-11-25T23:22:58.117" Score="5" Body="&lt;p&gt;From my days as a Navy communications officer, if you guarded a frequency such as 121.5MHZ you also had a transmitter set for that frequency as well as a receiver. If you only monitored a frequency, you only had a receiver tuned to it. We at least monitored both 121.5 and 243.0 any time we put out to sea. &lt;/p&gt;&#xA;" OwnerUserId="12421" LastActivityDate="2015-11-25T23:22:58.117" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23162" PostTypeId="1" AcceptedAnswerId="23163" CreationDate="2015-11-25T23:50:23.920" Score="7" ViewCount="2336" Body="&lt;p&gt;I have seen instructional sites that seem to indicate a 15 degree bank is a standard turn.  The Turn Coordinator has 15 and 30 degree marks on it.  Is 15 degrees a standard turn and what does this mean?  Is there a general way to figure out what the radius of such a turn is or how long it would take to fly a circle at 15 degrees bank?  Without trying to do the math, it seems that airspeed together with bank angle would determine the turn rate.  &lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2015-11-26T03:44:23.353" Title="For light, GA aircraft, is there a &quot;standard&quot; turn, and what does that mean?" Tags="&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23163" PostTypeId="2" ParentId="23162" CreationDate="2015-11-26T00:21:52.030" Score="9" Body="&lt;p&gt;The FAA &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot;&gt;Aeronautical Information Manual&lt;/a&gt; defines 'standard rate turn' as,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A turn of three degrees per second. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This results in the completion of a full circle in 2 minutes. Every airplane must be able to complete a standard rate turn in order to be certified. The standard rate of turn is used as the main reference for bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GA aircraft are expected to turn at the standard rate of turn during holding, intercepting, tracking, approaches, departures etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're correct that the airspeed determines the turn rate. As the turn rate is standardized, the bank angle becomes dependent on the air speed. From FAA-H-8083-15A Instrument Flying Handbook,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;True airspeed determines the angle of bank necessary to maintain a standard-rate turn. A rule of thumb to determine the approximate angle of bank required for a standard-rate turn is to divide your airspeed by 10 and add one-half the result. For example, at 60 knots, approximately 9° of bank is required (60 ÷ 10 = 6 + 3 = 9); at 80 knots, approximately 12° of bank is needed for a standard-rate turn.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-26T00:21:52.030" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23164" PostTypeId="2" ParentId="23162" CreationDate="2015-11-26T03:37:27.943" Score="5" Body="&lt;p&gt;The part of your question concerning the standard turn rate is already answered by aeroalias, so let me focus on the physics behind it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a turn the wing has to produce a centripetal force in addition to the lift $L$ needed to support the aircraft's weight $m\cdot g$, requiring a bank angle $\Phi$. The aircraft flying at a speed $v$ will experience a load factor $n_z$ exceeding unity:&#xA;$$n_z = \frac{L}{m\cdot g} = \frac{1}{cos\Phi}$$&#xA;The turn radius $R$ is&#xA;$$R = \frac{v^2}{g\cdot tan\Phi} = \frac{v^2}{g\cdot\sqrt{n_z^2-1}}$$&#xA;and the turn rate (expressed as angular velocity $\Omega$ in radians per second) of that turn is&#xA;$$\Omega = \frac{v}{R} = \frac{g\cdot tan\Phi}{v} = \frac{g\cdot\sqrt{n_z^2-1}}{v}$$&#xA;Now you can find out which radius and turn rate are flown with $\Phi$ = 15° of bank in a coordinated turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AjvHi.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AjvHi.png&quot; alt=&quot;Parameters for turns with 15° bank&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parameters for turns with 15° bank angle (own work). A turn rate of 3° per second can only be flown with 15° of bank at a speed of 50 m/s (97.2 kts). Flying slower will require less bank for the same turn rate or result in a higher turn rate for the same bank angle.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-26T03:44:23.353" LastActivityDate="2015-11-26T03:44:23.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23165" PostTypeId="2" ParentId="23138" CreationDate="2015-11-26T05:27:27.990" Score="7" Body="&lt;p&gt;This might be a stupid answer, but you can see a lot of take-off, landing videos from cockpit in YouTube.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's one:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/G3tiC321IG0?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="12424" LastActivityDate="2015-11-26T05:27:27.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23166" PostTypeId="1" AcceptedAnswerId="23168" CreationDate="2015-11-26T06:33:06.890" Score="9" ViewCount="6923" Body="&lt;p&gt;When I started searching for Heading Bug (other bugs like altitude, speed bugs), I didn't get much clear idea about it. Usually this is displayed on Horizontal Situation Indicator display on the direction of wind (calculated based on wind direction, speed?). This heading bug can be selected to a value by pilots during flight.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;What is the use of heading bug?&lt;/li&gt;&#xA;&lt;li&gt;how heading bug is calculated?&lt;/li&gt;&#xA;&lt;li&gt;what's the significance of heading bug?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-11-26T09:16:25.530" Title="What is the use of heading bug?" Tags="&lt;wind&gt;&lt;crosswind&gt;&lt;heading&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23167" PostTypeId="2" ParentId="23138" CreationDate="2015-11-26T07:43:27.990" Score="0" Body="&lt;p&gt;As stated in the comments, the view you get in a PC based flight simulator is not representative of the real thing. To get a decent approximation of what you actually see from an airliner cockpit you'd need at least 6 screens in 2 rows of 3 screens each.&lt;br/&gt;&#xA;This of course requires quite a bit of hardware to accomplish :(&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Using the virtual cockpit feature of some flight simulator software, and cranking up your viewpoint a bit from the default settings, you can get a much more authentic experience already but it's still limited by the tiny viewport offered by even a larger widescreen computer monitor (let alone a 17&quot; 4:3 display which is what many of them are programmed for as it's the smallest common denominator).&lt;br/&gt;&#xA;Of course that virtual cockpit has its own drawbacks in that the instruments are often a bit blurry and buttons and knobs less responsive than in the 2D view (let alone reality).&lt;br/&gt;&#xA;It's a set of compromises we have to live with as PC flyers, dictated by the limitations of our hardware and budgets.&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-11-26T07:43:27.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23168" PostTypeId="2" ParentId="23166" CreationDate="2015-11-26T08:00:23.393" Score="13" Body="&lt;p&gt;Bugs simply make instruments easier to read with a very quick glance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I need to steer exactly 162 degrees, which is easier?  To read where the needle is pointing or just see if the needle is pointing to the bug which I manually set to 162 degrees?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bugs are set by rotating knobs on the gauges.  Here, the heading bug knob is in the lower right corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OqIG8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OqIG8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I often use it is to turn onto the next heading required according to my plan, then set the bug to that heading so that I can simply glance at the needle (still pointing to the bug, good) to keep me on course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other uses:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If ATC gives you a &quot;next heading&quot;, you will read back the instruction, then you can set the bug to that next heading so that a), you don't forget it and need to call back and b) can simply turn onto the bug when it's time to turn.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Set it to the departure runway heading on take off.  To &quot;fly runway heading&quot;, just keep the bug at the top of the gauge.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On arrival, set it to the landing runway heading.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As a &quot;gross error&quot; check.  You would not believe how many inexperienced pilots set off in entirely the wrong direction.  As well as setting the heading bug to &quot;first leg of the plan&quot;, you check this along with &quot;and the road should be on my left with the river on my right&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On some simple autopilot systems, the autopilot follows the altitude and heading bugs rather than having controls for these settings on the autopilot itself.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-11-26T09:16:25.530" LastActivityDate="2015-11-26T09:16:25.530" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="23169" PostTypeId="2" ParentId="23157" CreationDate="2015-11-26T10:14:50.197" Score="4" Body="&lt;p&gt;Apart every possible aerodynamic consideration, wearing a wingsuit in the tiny space of a cockpit would be extremely difficult.&#xA;In the F-16, for instance, there are instruments, switches and the &lt;strong&gt;ejection seat handle&lt;/strong&gt; between the pilot legs (source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/5/51/F16_Cockpit,_Asian_Aerospace_2006.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7yCDD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7yCDD.jpg&quot; alt=&quot;F-16&amp;#39;s cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Limited arms' movement is another issue. Having parts of the suit randomly catching switches, levers, etc. will be a safety nightmare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, many fighter jet's don't have explosive bolts that release the canopy during ejection, but rather some cordite in the glass to break it during the ejection sequence, like the AV-8B Harrier II (source: &lt;a href=&quot;http://www.b-domke.de/AviationImages/Harrier/Images/1617.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.b-domke.de&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lQPqg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lQPqg.jpg&quot; alt=&quot;AV-8B Harrier II canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passing through a shattered glass with the aforementioned wingsuit could tear off some part or lead to injuries to the pilot.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2015-11-26T10:14:50.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23171" PostTypeId="1" CreationDate="2015-11-26T11:01:47.960" Score="2" ViewCount="354" Body="&lt;p&gt;How do airport authorities deal with with birds? Which procedures have acutually been used in order to minimize or even avoid birds on airside and landside? Is there any procedure that crew can perform in order to minimize the danger caused by birds?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="1467" LastEditDate="2015-11-26T11:52:08.893" LastActivityDate="2015-11-26T11:52:08.893" Title="How can bird hazard be avoided?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="0" ClosedDate="2015-11-26T12:51:15.623" ContentLicense="CC BY-SA 3.0" />
  <row Id="23172" PostTypeId="1" CreationDate="2015-11-26T11:07:07.787" Score="0" ViewCount="544" Body="&lt;p&gt;As per subject why are 4 engine turboprops not produced anymore for civilian flights if turboprops are so efficient?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How comes the military still use them (see Airbus A400 and C130)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be amazing to fly on a 150 seater powered by 4 propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What favours jet engines?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-12-04T19:20:43.183" Title="Why are 4 engine civilian turboprops not produced anymore" Tags="&lt;airliner&gt;&lt;turboprop&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-12-04T19:20:49.937" ContentLicense="CC BY-SA 3.0" />
  <row Id="23173" PostTypeId="1" AcceptedAnswerId="23198" CreationDate="2015-11-26T11:34:49.093" Score="10" ViewCount="8870" Body="&lt;p&gt;I have this question in my mind. I have been trying to look for this in different books about aerodynamics and I couldn't find the answer. I know I could check the answer experimentally, if I had a wind tunnel or some advanced software, but I don't have access to any of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say we have this plot (fig. 1) obtained experimentally by testing an airfoil at a low speed (subsonic) with a wind tunnel. If I were to change the wind speed of the wind tunnel, would the graph change or would it remain the same?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if the wind velocity was initially 15 m/s and then 25 m/s, would it change or is the CL-AoA relationship constant for a given airfoil?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just need to understand this, I don't need any example with numbers (I just give the numbers to have an order of magnitude of the velocities of the testing. And assume the airfoil has a regular shape, for instance a NACA0012, which is pretty common for academic examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MwvvH.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MwvvH.png&quot; alt=&quot;CL vs. AoA (Source: https://en.wikipedia.org/wiki/Lift_coefficient#/media/File:Lift_curve.svg)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8407" LastActivityDate="2021-04-12T03:37:47.070" Title="Does lift coefficient vary with the wind velocity for a given angle of attack?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;airfoil&gt;&lt;angle-of-attack&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23174" PostTypeId="2" ParentId="23171" CreationDate="2015-11-26T11:45:58.713" Score="2" Body="&lt;p&gt;Airports are responsible for bird control and should provide adequate wildlife control measures. Some major airports are provided with an ornithological department that has ravens or similar birds trained to drive away other birds from the airport premises. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this is not a 100% efficient solution and flight crews have procedures that must follow if birds are reported.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If large birds or flocks of birds are reported or observed near the runway, the flight crew should consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Delaying the takeoff or landing when fuel permits. Advise the tower and wait for airport action before continuing.&lt;/li&gt;&#xA;&lt;li&gt;Take off or land on another runway that is free of bird activity, if available.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To prevent or reduce the consequences of a bird strike, the flight crew should:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Discuss bird strikes during takeoff and approach briefings when operating at airports with known or suspected bird activity.&lt;/li&gt;&#xA;&lt;li&gt;Be extremely vigilant if birds are reported on final approach. If birds are expected on final approach, plan additional landing distance to account for the possibility of no thrust reverser use if a bird strike occurs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;References: &lt;a href=&quot;http://www.birdstrike.org&quot; rel=&quot;nofollow&quot;&gt;http://www.birdstrike.org&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/&quot; rel=&quot;nofollow&quot;&gt;http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8407" LastActivityDate="2015-11-26T11:45:58.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23175" PostTypeId="2" ParentId="23171" CreationDate="2015-11-26T11:48:24.143" Score="1" Body="&lt;p&gt;The airport authorities use a number of techniques to manage the hazard of bird strike in and near airports. These include,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Elimination of bird habitats- Birds usually come to the airport area due to the availability of food sources. Denial of food to birds by eliminating the sources (like landfills, garbage, crops, dumps etc) will reduce the chance of birdstirke by eliminating the source.&lt;/p&gt;&#xA;&lt;p&gt;It also helps to keep the airport and surrounding areas unattractive to birds (for example, by eliminating water stagnation, vegetation cover etc) as it prevents the birds from nesting there.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scaring them away- A number of airports use a number of bird repellents like pyrotechnics, cannons (mostly just prior to aircraft approach to prevent bird habituation), chemical repellents etc.&lt;/p&gt;&#xA;&lt;p&gt;In some cases, specially trained animals (like falcons, dogs etc) have been used to scare away the birds or they are trapped.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In some cases, the flight schedule can be altered if bird movement is expected in the area (for example, if the airport is on a bird migration route).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The problem can be solved by simply killing the birds in the area, though this drastic step is usually not implemented except in the most extreme cases. In general, the nesting sites of birds are destroyed to prevent them from staying permanently near the airport.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Usually, a combination of above methods is used to manage the birds.&lt;/p&gt;&#xA;&lt;p&gt;The only procedure available for flight crews is to either delay the flight (or land in alternate runway if its available) in case birds are detected over an area. This however, is dependent on a number of variables like fuel availability, flight schedule etc. There are some radar systems under development that could detect birds; however, these have not reached operational stage yet.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-26T11:48:24.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23176" PostTypeId="1" CreationDate="2015-11-26T12:59:20.150" Score="15" ViewCount="5413" Body="&lt;p&gt;I had a flight yesterday on an AA Embraer ERJ-190. As the plane idled at the end of the runway there was the familiar high-pitched jet whistle, which increased in pitch as the engine started spinning up. But, when it reached full power, the whistle was joined by a far-lower-pitched metallic whine, which persisted until the pilot throttled down after the initial steep climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard this before on some (but not all?) planes. By ear, the whistle was about four an a half octaves above the whine, which is about a factor of 24 (I may have been off by an octave, or another factor of two).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a past flight I calculated that if the main fan spun so that its outer edge was moving at the speed of sound, the whine would be at about the rotational frequency of the fan. If the fan had 24 blades (or 48 if I have the wrong octave) then the whistle could be the fan blades, and the whine the fan itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One explanation could be that there's something asymmetrical about the fan, e.g. one blade is a bit too long and hits the housing when at full power. (Of course, this would make no sense from an engineering and reliability standpoint.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What causes that far-lower-pitched metallic whine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; I just returned on a JetBlue flight, but also using an ERJ-190. Where before I was seated in row three, this time I was in row 24 of 25. On takeoff, there was only a loud roar; no &quot;whine&quot; or &quot;whistle&quot;. So, it's pretty clear that the noises I'm referring to above are emitted from the engine intake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, &lt;a href=&quot;http://www.scanliners.com/AircraftDemos/ERJ190_CRJ900.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;on this page&lt;/a&gt; I found a photo of the ERJ-190's GE CF34-10E Efficient Engine's inlet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I5dlb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I5dlb.png&quot; alt=&quot;ERJ-190 GE CF34-10E Efficient Engine inlet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sure enough, the intake fan has 24 blades. So, my above guess on the frequency ratio between my &quot;whine&quot; and &quot;whistle&quot; has some physical basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, I'd like to respond to a comment by @kevin:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Could it be that the &quot;whine&quot; always exists in the frequency spectrum, but it's just below our human ear detection threshold (both pitch and amplitude) during low rpm operation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;When the &quot;whine&quot; starts and ends, my impression is that yes, the pitch rises as it initially strengthens, and falls as it finally fails. However, its volume is strongly pitch-dependent, so that it is far quieter when running at 80% of the maximum pitch/RPM, and inaudible below that. It sounds as if that blade which purportedly hits the housing only does so above a certain RPM (again: this is what it sounds like, it almost certainly is not what is actually happening). More generally, my interpretation is that the cause of the &quot;whine&quot; only happens above a certain RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit 2:&lt;/strong&gt; @fooot was kind enough to point out &lt;a href=&quot;https://aviation.stackexchange.com/questions/14492&quot;&gt;another question&lt;/a&gt; that is basically a duplicate. My text and suppositions are (I think) a lot clearer, but the other question links to two videos that demonstrate exactly what I've been talking about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=2m9l-nDd1fw&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A320 with IAE V2500 engine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=8HAgps44RHE&amp;amp;feature=youtu.be&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A320 with CFM56 engine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Neither of the answers to the other question are correct; one focuses on the fan blade noise (too high-pitched) and the other on pressure equalization vents (not engine-speed related).&lt;/p&gt;&#xA;" OwnerUserId="9825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-03-07T15:56:51.877" Title="Why does a jet engine acquire a metallic whine when in full power?" Tags="&lt;jet-engine&gt;&lt;noise&gt;&lt;compressor&gt;" AnswerCount="3" CommentCount="5" ClosedDate="2016-03-07T17:46:03.537" ContentLicense="CC BY-SA 3.0" />
  <row Id="23177" PostTypeId="2" ParentId="23172" CreationDate="2015-11-26T13:12:22.900" Score="-1" Body="&lt;p&gt;Well, military turbo-props are supposed to carry a large load at lower speeds, they wouldn't work well in passenger airplanes now because a jet plane can carry the same amount of passengers for a longer distance and faster than a turbo-prop can. However, they still use double-engined ones because they fly short, low-density routes to save money over using larger jet planes.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-26T13:12:22.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23179" PostTypeId="1" CreationDate="2015-11-26T13:19:15.450" Score="6" ViewCount="8284" Body="&lt;p&gt;If there is a medical emergency on board, on a passenger or crew member, will the crew be cleared to use PAN PAN/MAYDAY MEDICAL on their R/T?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any DOC in which regulates these phraseology?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="14897" LastEditDate="2016-10-20T04:22:55.380" LastActivityDate="2020-07-29T09:31:24.603" Title="Can pilots use PAN PAN Medical, even if they were not on MedEvac mission?" Tags="&lt;phraseology&gt;&lt;medevac&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23180" PostTypeId="2" ParentId="23179" CreationDate="2015-11-26T13:27:40.613" Score="10" Body="&lt;p&gt;The UK CAA Radiotelephony Manual (CAP 413) has the following to say about it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PAN PAN MEDICAL is not used in the UK but refers to a Geneva&#xA;  Convention term associated with medical transportation by parties&#xA;  involved in a conflict.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Use of this term is not appropriate in the UK.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which seems to be a pretty definitive no. Personally, I'd not heard of the term but assuming the CAA's interpretation of the ICAO's definition (i.e., for use during war) then I can't imagine it ever being appropriate outside of that use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, why would you need to? Using a normal MAYDAY or PAN call and describing the emergency as a medical one is perfectly acceptable and would be fully understood by all parties.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-11-26T13:27:40.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23181" PostTypeId="1" AcceptedAnswerId="23187" CreationDate="2015-11-26T13:38:21.193" Score="3" ViewCount="337" Body="&lt;p&gt;Considering wide body aircraft, why do emergencies, related to hydraulic system failure, increase the landing distance?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="19" LastEditDate="2016-11-21T14:40:30.853" LastActivityDate="2016-11-21T14:40:30.853" Title="Why does a hydraulic system failure increase the landing distance?" Tags="&lt;safety&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23182" PostTypeId="2" ParentId="23179" CreationDate="2015-11-26T13:42:51.290" Score="6" Body="&lt;p&gt;No. The phrase 'PAN PAN Medical' is reserved exclusively for medical transports. From ICAO &lt;a href=&quot;http://www.icao.int/Meetings/anconf12/Document%20Archive/AN10_V2_cons%5B1%5D.pdf&quot; rel=&quot;noreferrer&quot;&gt;Annex 10 to the Convention on International Civil Aviation- Aeronautical Telecommunications Volume II&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For the purpose of announcing and identifying aircraft used for medical transports, a transmission of the radiotelephony urgency signal PAN PAN, preferably spoken three times, and each word of the group pronounced as the&#xA;French word “panne”, shall be followed by the radiotelephony signal for medical transports MAY-DEE-CAL, pronounced as in the French “médical”. The use of the signals described above indicates that the message which follows concerns a protected medical transport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;However, the pilot can use PAN-PAN followed by request for medical advise if the situation is urgent. According to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Air Traffic Organization Policy, Air Traffic Control&lt;/a&gt;, PAN-PAN is used in case of urgency.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word “Mayday,” preferably repeated three times. For an Urgency condition, the word “Pan-Pan” should be used in the same manner.&lt;/p&gt;&#xA;&lt;p&gt;PAN-PAN- The international radio-telephony urgency signal. When repeated three times, indicates uncertainty or alert followed by the nature of the&#xA;urgency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, PAN-PAN followed by request for medical advise is ok.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-26T13:42:51.290" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23183" PostTypeId="2" ParentId="23181" CreationDate="2015-11-26T13:43:34.550" Score="2" Body="&lt;p&gt;In most wide body aircraft hydraulics are used to lower flaps, raise spoilers, and in some cases apply wheel brakes. A flaps up landing is going to mean a higher landing speed, no spoilers will mean less drag to slow the aircraft, and not having wheel brakes will mean a much longer roll-out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also worth noting is that a hydraulic failure which will impact those systems will probably impact flight control surfaces as well, and landing gear extension, so a longer landing distance is the least of a pilot's worries in that situation. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-11-26T13:43:34.550" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23184" PostTypeId="2" ParentId="23181" CreationDate="2015-11-26T14:07:46.127" Score="5" Body="&lt;p&gt;Any hydraulic failure will affect the landing distance as most of aircraft controls are operated by hydraulics.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the high lift devices (flaps) become inoperative (or become degraded) due to hydraulic failure, the aircraft will have a higher approach speed, which will increase the landing distance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Hydraulics are also used for operating a number of other systems like brakes, ground spoilers and thrust reversers. Any degradation in their operation will increase landing distance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-26T14:07:46.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23185" PostTypeId="1" AcceptedAnswerId="23186" CreationDate="2015-11-26T16:15:56.467" Score="4" ViewCount="999" Body="&lt;p&gt;One of things which consistently amazes me about flight is the exceptional progress in the early decades of flight - especially in terms of avionics. Wikipedia tells me that the first ILS landing was in 1938.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to understand more about the early development of gyroscopic flight instruments - in particular, what the first instruments like? When were they first put to use?&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-11-26T16:51:54.443" Title="What and when was the first gyroscopic flight instrument introduced?" Tags="&lt;gyroscopic-instruments&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23186" PostTypeId="2" ParentId="23185" CreationDate="2015-11-26T16:45:54.300" Score="3" Body="&lt;p&gt;It appears that the first gyroscopic flight instrument in aviation was a gyroscopic stabilizer, with the purpose of &lt;a href=&quot;http://flightclub.jalopnik.com/lawrence-sperry-inventor-of-the-autopilot-and-the-m-1592623110&quot; rel=&quot;nofollow noreferrer&quot;&gt;maintaining stability and control in a Curtiss C-2 biplane&lt;/a&gt;; it was first used (publicly) in 1914.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this, the inventors, &lt;a href=&quot;https://en.wikipedia.org/wiki/Elmer_Ambrose_Sperry&quot; rel=&quot;nofollow noreferrer&quot;&gt;Elmer A&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lawrence_Sperry&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lawrence B Sperry&lt;/a&gt; were awarded the Collier Trophy in 1914. Apparently &lt;a href=&quot;http://www.historynet.com/lawrence-sperry-autopilot-inventor-and-aviation-innovator.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;they did this&lt;/a&gt; by,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...linking the control surfaces with three gyroscopes, allowing flight corrections to be introduced based on the angle of deviation between the flight direction and the original gyroscopic settings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iEseP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iEseP.jpg&quot; alt=&quot;Stabilizer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Lawrence Sperry and gyroscopic stabilizer&lt;/em&gt;, Image from wright-brothers.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The device (with the gyroscopes spinning at 7000 rpm) was &lt;a href=&quot;http://www.wright-brothers.org/History_Wing/History_of_the_Airplane/Decade_After/Girding_for_Battle/Girding_for_Battle.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;first tested by Lawrence Sperry and Berringer&lt;/a&gt; on a Curtiss F aircraft in 1913, with the first public flight in 1914.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6D9tg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6D9tg.jpg&quot; alt=&quot;First gyro flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sperry’s second flyby in Paris in the 1914 competition, with Emil on the wing&lt;/em&gt;. Image from historicwings.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elmer &lt;a href=&quot;http://www.nationalaviation.org/sperry-sr-elmer/&quot; rel=&quot;nofollow noreferrer&quot;&gt;went on to develop&lt;/a&gt; the turn and bank indicator and an optical drift indicator, for which he was awarded the Collier trophy again in 1916.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-26T16:51:54.443" LastActivityDate="2015-11-26T16:51:54.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23187" PostTypeId="2" ParentId="23181" CreationDate="2015-11-26T17:12:10.400" Score="5" Body="&lt;p&gt;Landing distance is a function of the formula&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Kinetic Energy = 1/2 * mass * velocity²&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Any change that will increase kinetic energy will require longer landing distances.  When we land, the kinetic energy needs to go somewhere.  It can be converted into heat with the brakes, opposed with drag from the thrust reversers or deployed spoilers&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Higher landing speed will cause an increase kinetic energy that must be converted on landing and thus you will have a longer landing distance.&lt;/li&gt;&#xA;&lt;li&gt;Braking, thrust reverser or spoiler issues will increase the landing distance because they will not be as effective (take more time) in converting kinetic energy.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In a hydraulic issue, most likely the manufacturer has chosen to fly the airplane at a speed greater than needed for a normal landing (VREF + 20) and will most likely not have the ability to use normal braking.  Most jets use hydraulic fluid to stop the brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the jets I fly, without normal braking means we use the emergency brakes which are not routed through the anti-skid system so precaution must be taken to not skid the tires.  This all adds up to a substantial landing distance penalty.  Hare the landing distances for some airplanes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Learjet family: Factor of 3.15&lt;/li&gt;&#xA;&lt;li&gt;Learjet 45 family:  Factor of 2.2&lt;/li&gt;&#xA;&lt;li&gt;Challenger 604 family: Factor of 1.7 (braking) times 1.8 (airspeed) for a total of 3.06&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-11-26T17:12:10.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23188" PostTypeId="1" AcceptedAnswerId="23189" CreationDate="2015-11-26T17:12:33.653" Score="6" ViewCount="1165" Body="&lt;p&gt;On many airplanes (you can take the &lt;a href=&quot;https://www.google.it/url?sa=i&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=images&amp;amp;cd=&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwii6ej4x67JAhVGcRQKHZ0DBvkQjRwIBw&amp;amp;url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DsTQo8k_NfaA&amp;amp;bvm=bv.108194040,d.d24&amp;amp;psig=AFQjCNEtTKDsMZ2HeVjdOcQ9A2-Hqso5ag&amp;amp;ust=1448643557470799&quot; rel=&quot;noreferrer&quot;&gt;A330&lt;/a&gt; to make an example), the fuselage is not completely covered by windows. In some cases it is due to the presence of the lateral emergency exit, in some other cases I am not sure about the reason. Usually it's above the wings, so I made my idea but I want to know for sure the real reason! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the linked video, for example, one windows is missing under the &quot;R&quot; of the &quot;Garuda&quot; logo in the fuselage. &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="6886" LastEditDate="2015-11-26T23:20:33.730" LastActivityDate="2015-11-27T12:00:22.317" Title="Why would a passenger airliner be missing windows in the fuselage?" Tags="&lt;windows&gt;&lt;fuselage&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23189" PostTypeId="2" ParentId="23188" CreationDate="2015-11-26T17:15:59.093" Score="11" Body="&lt;p&gt;Most of them are where there is a divider between sections or there is a lavatory there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are the layouts for the Garuda A330-200 and -300. As you can see the divider between the classes (Between Blue row 11 and green row 21) and the lavatories (Between rows 31 and 32) are located where the missing windows are in the video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-300:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yIvEA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yIvEA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-200:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N1TMU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N1TMU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Images by Garuda Airlines&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-11-26T17:29:25.753" LastActivityDate="2015-11-26T17:29:25.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23190" PostTypeId="1" AcceptedAnswerId="23193" CreationDate="2015-11-26T17:16:15.217" Score="8" ViewCount="234" Body="&lt;p&gt;Right now (26/11/2015, UTC 17:16), British Airways is flying over the Australian Outback with two Boeing 777-336(ER)s, christened flight &lt;strong&gt;BA15&lt;/strong&gt; (&lt;a href=&quot;http://www.flightradar24.com/BAW15/8169bb5&quot; rel=&quot;nofollow&quot;&gt;http://www.flightradar24.com/BAW15/8169bb5&lt;/a&gt;) and &lt;strong&gt;BA15X&lt;/strong&gt;, which is slightly ahead (&lt;a href=&quot;http://www.flightradar24.com/BAW15X/8169237&quot; rel=&quot;nofollow&quot;&gt;http://www.flightradar24.com/BAW15X/8169237&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? Is flight &lt;strong&gt;BA15X&lt;/strong&gt; a logistic one? And if not, why did they use an &quot;X&quot; to distinguish between the two instead of another number?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am also wondering: is this going to cost extra money to &lt;code&gt;BA&lt;/code&gt;, owing to the new slot they had to purchase or rent for operating a contemporary, second aircraft at &lt;code&gt;SYD&lt;/code&gt;?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="19" LastEditDate="2016-11-21T14:42:08.767" LastActivityDate="2016-11-21T14:42:08.767" Title="Is this BA15X flight a logistic flight for British Airways?" Tags="&lt;flight-planning&gt;&lt;boeing-777&gt;&lt;australia&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23191" PostTypeId="2" ParentId="16023" CreationDate="2015-11-26T18:37:56.777" Score="3" Body="&lt;p&gt;One peculiarity was that the Pakistanis had a clause in their agreement with the Chinese that the JF-17 not be an F-7/Super 7 upgrade. Yet, the similarities to the Super 7 are quite obvious. If not actually based on the Super 7, then there is at least some commonality of design philosophy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The truth is, it's impossible to tell. However, even if far back in it's genes there is still elements of the MiG-21 that wouldn't be so extraordinary. The F-18 if you go back, has parts of the F-5, which itself was based upon a 1950s fighter, the N156! As a slight twist, the Super 7 has elements of the F-20 Tigershark, which is an updated F-5.&lt;/p&gt;&#xA;" OwnerUserId="12429" LastActivityDate="2015-11-26T18:37:56.777" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23192" PostTypeId="2" ParentId="23117" CreationDate="2015-11-26T18:41:04.443" Score="0" Body="&lt;p&gt;The Super 7, an updated J-7, the Chinese MiG-21, had a new nose and intakes. Basically, an F-20 Tigershark grafted onto the fuselage of a J-7 (Grumman were consultants on the project). As such, you can, in effect, see a MiG-21 with a more modern nose.&lt;/p&gt;&#xA;" OwnerUserId="12429" LastActivityDate="2015-11-26T18:41:04.443" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23193" PostTypeId="2" ParentId="23190" CreationDate="2015-11-26T19:25:10.523" Score="7" Body="&lt;p&gt;The Wednesday flight was indeed delayed for a full day as was suggested in a comment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T4SYu.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T4SYu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2015-11-26T19:25:10.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23194" PostTypeId="1" AcceptedAnswerId="23196" CreationDate="2015-11-26T19:38:05.540" Score="5" ViewCount="585" Body="&lt;p&gt;&lt;a href=&quot;http://arstechnica.com/cars/2015/11/airbus-proposes-new-drop-in-airplane-cabin-modules-to-speed-up-boarding/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ars Technica recently reported&lt;/a&gt; that Airbus filed a patent for a detachable cabin module that would speed loading and unloading of passengers (otherwise known as self-loading freight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0U6LR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0U6LR.jpg&quot; alt=&quot;Detachable cabin module&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This does seem like it might improve turnaround time since passengers are rather slow to self-load and self-unload. That's not my question (which is in fact an earlier &lt;a href=&quot;https://aviation.stackexchange.com/questions/12300/why-dont-airlines-load-their-passengers-like-freight&quot;&gt;question&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is that I had always imagined the strength of an airframe was due to its long cylindrical shape. This is both in terms of it as a pressurized tube as well as lateral strength from bending forces. &lt;strong&gt;The detachable cabin module would seem to defeat all of these advantages.&lt;/strong&gt; Am I correct in this understanding? Are there ways that the Airbus patent mitigates them?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-11-27T03:16:21.020" Title="How would a detachable cabin module work?" Tags="&lt;aircraft-design&gt;&lt;passenger&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23196" PostTypeId="2" ParentId="23194" CreationDate="2015-11-26T21:06:28.553" Score="5" Body="&lt;p&gt;You are right, this patent looks like it will not work in reality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuselages have to carry two primary loads:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pressurisation loads, which cause uniform tension in lengthwise and circumferential direction, and&lt;/li&gt;&#xA;&lt;li&gt;bending loads from inertial and control surface loads, which create both tension and compression loads in lengthwise direction, plus some shear.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Reducing the height of the fuselage will drive up the strain from the bending loads, so more material is needed to transmit them. Also, the bottom of the passenger compartment and especially the corners at the lower edges will experience much higher loads than a cylindrical fuselage ever would under pressurization. Again, to make this work needs a much beefier structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The loads could be kept the same if the passenger compartment is tightly bolted to the remaining aircraft structure such that the combination of &quot;flatbed&quot; fuselage and passenger compartment can be considered as a contiguous structure, but this would need redundancy in the connections and would make fitting the passenger compartment non-trivial. Airbus is arguing in this direction, but I wonder how much time can be saved and how much maintenance time is added if the primary structure of the fuselage is torn apart and re-joined at every stop. Note that you not only need to connect the parts at each end, but to transfer pressurization loads you need to bolt them together along the full length of the passenger cabin as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today's airliners are already designed to survive partial depressurization, such that the lower fuselage is depressurized without the pressure loads in the upper part causing damage. Therefore, the fact that both parts can be split and can depressurize independently of each other does not add additional load cases. However, the structure today is dimensioned to sustain those loads only for a short time. Pressurizing only the passenger compartment or not joining the parts along the full length for every flight will need a much stronger structure than what is used today, so the weight impact of a simpler way of joining both parts will most likely result in an economically unattractive outcome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did not go into detailed calculations, but I strongly suspect that this idea will not be adopted by airlines. Besides the structural impact, such a way of loading passengers would complicate logistics, since a fitting passenger container plus facilities for mounting it on the aircraft must be available at the departure and destination airfields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, proposals like this &lt;a href=&quot;http://pdfpiw.uspto.gov/.piw?Docid=02388380&amp;amp;homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO2%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526co1%3DAND%2526d%3DPALL%2526s1%3D2388380.PN.%2526OS%3DPN%2F2388380%2526RS%3DPN%2F2388380&amp;amp;PageNum=&amp;amp;Rtype=&amp;amp;SectionNum=&amp;amp;idkey=NONE&amp;amp;Input=View%20first%20page&quot; rel=&quot;nofollow noreferrer&quot;&gt;are not exactly new&lt;/a&gt;, which is why the first claim extends over 73 lines to be narrow enough to not conflict with earlier patents or publications. If there had been some value in this idea, we would had seen it being adopted long ago.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In helicopters, however, which fly at altitudes where no pressurization of the passenger compartment is needed, this idea has been tried out before. See below a picture of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_S-64_Skycrane&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sikorsky S-64 Skycrane&lt;/a&gt; carrying a container (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/3/30/Sikorsky_Skycrane_carrying_container_bw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) in which passengers could be carried.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CeGhz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CeGhz.jpg&quot; alt=&quot;Sikorsky S-64 Skycrane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-26T21:22:51.987" LastActivityDate="2015-11-26T21:22:51.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23197" PostTypeId="2" ParentId="23097" CreationDate="2015-11-26T21:44:50.597" Score="4" Body="&lt;p&gt;Normally, baggage &lt;a href=&quot;https://aviation.stackexchange.com/questions/23099/how-is-passenger-baggage-transferred-and-how-does-it-happen-so-quickly/23105#23105&quot;&gt;takes much longer to switch flights&lt;/a&gt; than self-loading cargo, so your scenario is highly unlikely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of a passenger missing and his/her baggage already on board, all bags need to be unloaded until the orphaned bag is found. When ULDs are used, those must be unloaded first and are then unpacked, mostly on the apron next to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Waiting for the missing passenger is an open-ended game. At some point, you must decide on a course of action with a fixed exit so you can move on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, every airline is required to unload an orphaned bag. I am sure &lt;a href=&quot;https://en.wikipedia.org/wiki/El_Al&quot; rel=&quot;nofollow noreferrer&quot;&gt;some are more strict&lt;/a&gt; about this than others.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-11-26T21:44:50.597" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23198" PostTypeId="2" ParentId="23173" CreationDate="2015-11-26T21:58:08.173" Score="12" Body="&lt;p&gt;Yes, it does vary slightly due to viscous effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as &quot;seen&quot; by the outer flow. This influence is captured by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9912/is-the-reynolds-number-a-function-of-the-fluid-flow-stream-or-the-obstruction/9915#9915&quot;&gt;Reynolds number&lt;/a&gt;. See below for a plot of the venerable NACA 4412 from &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19930090976&quot; rel=&quot;noreferrer&quot;&gt;Abbott and Doenhoffs collection of airfoil data&lt;/a&gt; (picture &lt;a href=&quot;http://voiletech.free.fr/Eolienne/PolaireNACA4412.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O19V2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O19V2.jpg&quot; alt=&quot;NACA 4412 lift curve and drag polar&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-11-26T21:58:08.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23199" PostTypeId="2" ParentId="2903" CreationDate="2015-11-26T22:48:45.997" Score="4" Body="&lt;p&gt;To understand this, I like to think of a jet with afterburner pointed nearly vertical. It's not stalled, the angle of attack is nearly 0, because the relative wind is going nearly straight down due to all the thrust. But &quot;straight down&quot; is still going smoothly across the wings, no stall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, a Cessna 172 going 10 kts ground speed, pitched level to the horizon, is going to be decending far faster than the 10 kts of ground speed, so the relative wind is hitting the bottom of the wing. Just another way of describing a high angle of attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may only make sense in my head, but it works for me. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-11-26T22:48:45.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23200" PostTypeId="2" ParentId="11760" CreationDate="2015-11-26T22:58:02.597" Score="3" Body="&lt;p&gt;The airport authorities use a number of techniques to manage the hazard of bird strike in and near airports. These include,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Elimination of bird habitats- Birds usually come to the airport area due to the availability of food sources. Denial of food to birds by eliminating the sources (like landfills, garbage, crops, dumps etc) will reduce the chance of birdstirke by eliminating the source.&lt;/p&gt;&#xA;&lt;p&gt;It also helps to keep the airport and surrounding areas unattractive to birds (for example, by eliminating water stagnation, vegetation cover etc) as it prevents the birds from nesting there.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scaring them away- A number of airports use a number of bird repellents like pyrotechnics, cannons (mostly just prior to aircraft approach to prevent bird habituation), chemical repellents etc.&lt;/p&gt;&#xA;&lt;p&gt;In some cases, specially trained animals (like falcons, dogs etc) have been used to scare away the birds or they are trapped.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In some cases, the flight schedule can be altered if bird movement is expected in the area (for example, if the airport is on a bird migration route).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The problem can be solved by simply killing the birds in the area, though this drastic step is usually not implemented except in the most extreme cases. In general, the nesting sites of birds are destroyed to prevent them from staying permanently near the airport.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Usually, a combination of above methods is used to manage the birds.&lt;/p&gt;&#xA;&lt;p&gt;The only procedure available for flight crews is to either delay the flight (or land in alternate runway if its available) in case birds are detected over an area. This however, is dependent on a number of variables like fuel availability, flight schedule etc. There are some radar systems under development that could detect birds; however, these have not reached operational stage yet.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-26T22:58:02.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23202" PostTypeId="1" CreationDate="2015-11-27T05:20:48.093" Score="3" ViewCount="1844" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/23166/what-is-the-use-of-heading-bug&quot;&gt;From this question&lt;/a&gt;, it is been suggested to ask different question, rather than keep discussing it under comment section.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How is the heading bug calculated and used for navigation when there is a cross wind? &lt;/li&gt;&#xA;&lt;li&gt;&amp;hellip; when there is a tail wind?&lt;/li&gt;&#xA;&lt;li&gt;Will the heading bug matter for navigation when there is wind correction required?&lt;/li&gt;&#xA;&lt;li&gt;What role does the heading bug play in autopilot mode?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2018-11-03T06:29:31.417" Title="How heading bug is calculated during cross wind and tail wind?" Tags="&lt;navigation&gt;&lt;wind&gt;&lt;crosswind&gt;&lt;heading&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23203" PostTypeId="2" ParentId="23202" CreationDate="2015-11-27T06:01:53.767" Score="2" Body="&lt;ol&gt;&#xA;&lt;li&gt;For cross-wind corrections: on the ground you can use a nice software or even an ol' CRP to &lt;a href=&quot;https://en.wikipedia.org/wiki/Wind_triangle&quot; rel=&quot;nofollow&quot;&gt;compute a drift&lt;/a&gt;. For setting the heading bug though, and for computing this in the cockpit, you need a quick way of doing it in your head: one great method involves the 'watch face' : &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;A) Divide the wind speed (in knots) by your NPM( nautical miles per minute). This is your Max Drift. &#xA;B) Use the watch face to determine how much of that Max Drift you need to use: 15 is a quarter of an hour, so for 15 degrees you use 1/4, 30 degrees you use 1/2 of Max Drift, 45 deg 3/4 and for larger degrees use the hole Max Drift&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;eg. wind 230/45 , your speed 180 kts (or 3 miles per minute), hdg 270&#xA;&#xA;   Max Drift = 45 / 3 = 15 degrees&#xA;   Angle between wind and me : 40 degrees, so I use a little more than 1/2 and less than 3/4 &#xA;  (between 30 and 45 on the watch face)&#xA;   Computed Drift = 10 degrees&#xA;   Set Hdg Bug to 260 to keep track 270&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;Hdg bug will not be affected by tail wind, but your ground speed and ETA will be affected. A CRP or an apropriate app  sheet can tell you by how much.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It will matter if a) wind is very strong or b) your navigation leg is long enough (30+ mins)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Depending on the sophistication of the autopilot, most of them have a &quot;keep heading mode&quot; where the a/c will maintain the heading selected by the heading bug. If operated in that mode, the pilot can turn the a/c by moving the hdg knob left or right.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="419" LastActivityDate="2015-11-27T06:01:53.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23204" PostTypeId="1" AcceptedAnswerId="23206" CreationDate="2015-11-27T09:10:04.107" Score="1" ViewCount="815" Body="&lt;p&gt;I have noticed that different airlines (like LIDO, Delta, AA, etc.) have different formats for their trip paperwork packages, containing pre-flight information that they give to their pilots.  These packages contain things like their flight plan, NOTAM's, weather, weight &amp;amp; balance, etc. There is some overlap of course, but I was wondering if FAA/EASA has some standard or guideline for generating the package?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="69" LastEditDate="2015-12-05T19:49:24.100" LastActivityDate="2015-12-05T19:49:24.100" Title="Is there a standard for the trip paperwork packages that are used by the airlines?" Tags="&lt;airline-operations&gt;&lt;preflight&gt;&lt;flight-plans&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23205" PostTypeId="2" ParentId="23204" CreationDate="2015-11-27T10:00:13.920" Score="1" Body="&lt;p&gt;The international standard is the ICAO flight plan. For national flights different formats may be allowed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Plan_Filling&quot; rel=&quot;nofollow&quot;&gt;this article on SKYbrary&lt;/a&gt; for details on what the ICAO flight plan contains.&lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-11-27T10:00:13.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23206" PostTypeId="2" ParentId="23204" CreationDate="2015-11-27T10:30:46.740" Score="2" Body="&lt;p&gt;For national flights, FAA &lt;em&gt;prefers&lt;/em&gt; ICAO flight plan. For international flights, ICAO format &lt;em&gt;must&lt;/em&gt; be used, From &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/flight_plan_filing/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Flight Planning Information&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA prefers users to file ICAO format flight plans for all flights. An ICAO format flight plan MUST be used when:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight will enter international airspace, including oceanic airspace controlled by FAA facilities.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight expects routing or separation based on Performance Based Navigation (PBN), e.g. RNAV 1.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight will enter RVSM airspace.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight expects services based on ADS-B.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;EASA follows a format similar to ICAO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight plan usually consists of the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft type and identification.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flight Rules.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Equipment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Source, destination, departure time and (estimated) arrival time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Route details.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;among other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the ICAO international flight plan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9bJQ9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9bJQ9.png&quot; alt=&quot;ICAO flight plan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Form 7233-4 - Pre-Flight Pilot Checklist and International Flight Plan&lt;/em&gt; from faa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following shows the domestic flight plan from FAA. Note that the ICAO format may be followed in domestic flights too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DpJws.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DpJws.png&quot; alt=&quot;National flight plan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Form 7233-1 - Flight Plan&lt;/em&gt; from faa.gov&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-27T10:30:46.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23207" PostTypeId="2" ParentId="23204" CreationDate="2015-11-27T10:59:10.280" Score="1" Body="&lt;p&gt;There are no guidelines by FAA/EASA for preparing flight plans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/flight_plan_filing/&quot; rel=&quot;nofollow&quot;&gt;per FAA,&lt;/a&gt; criteria for International (ICAO) Flight Plan Filing are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA prefers users to file ICAO format flight plans for all flights. An ICAO format flight plan MUST be used when:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight will enter international airspace, including oceanic airspace controlled by FAA facilities.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight expects routing or separation based on Performance Based Navigation (PBN), e.g. RNAV 1.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight will enter RVSM airspace.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;The flight expects services based on ADS-B.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is a form in Aeronautical Information Manual (AIM) Section 1, Paragraph 5-1-9 that need to be filled with all the required information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Criteria for Domestic Flight Plan Filing are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Flights that remain wholly within domestic United States airspace, and do not meet any of the criteria requiring an ICAO format flight plan, may use an FAA domestic format flight plan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is a form in AIM Section 5-1-8 (FAA Form 7233-1) that needs to be filled with all the required information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;File the Flight Plan by any of the following methods.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Submit a hard-copy flight plan form to your local flight service&#xA;station.&lt;/li&gt;&#xA;&lt;li&gt;Call Flight Services (1-800-WX-BRIEF or 1-800-992-7433) – The flight services specialist will file your flight plan.&lt;/li&gt;&#xA;&lt;li&gt;Submit your plan online through one of the following free services:&#xA;     - Direct User Access Terminal (DUAT)&#xA;     - Direct User Access Terminal Service (DUATS)&#xA;     - Lockheed Martin Flight Services&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Note: All the information is available in www.faa.gov&lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-11-27T10:59:10.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23208" PostTypeId="2" ParentId="5139" CreationDate="2015-11-27T11:26:19.750" Score="0" Body="&lt;p&gt;The big problem with flying even small models near aircraft, is this: the model might only weigh a few kg and not fly very fast. Lets say 5kg and 40mph. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you fly it near a light aircraft thats coming into land. This is doing 70 knots = almost 80mph. Thats a 5kg hard (ish) object hitting something at 120mph. If it hits the pilots windscreen, which is only thin perspex, it could kill or badly injure the pilot and everybody on board could be killed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you apply this to a jetliner, sure it might be harder to smash the windsceen, but the jetliner is doing 130 knots on approach - going on 150mph, so that makes a 190mph closing speed, which again could do a lot of damage. Even if the model is hovering, the closing speed is still the speed of the large aircraft and the amount of energy in the impact is related to the square of the speed and the weight, so double the speed at a given weight, you get four times the impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There should be no question in my mind, by all means play with these things, but if you have a loaded gun, most sane people would keep well away from pointing it at somebody. If you have any thought for other people (and your own conscience and freedom), then it should be the same with these things. &lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-11-27T11:26:19.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23209" PostTypeId="1" CreationDate="2015-11-27T11:42:21.077" Score="40" ViewCount="2637" Body="&lt;p&gt;The Eurofighter Typhoon has an interesting &quot;feature&quot; in that the nose gear door is shorter than the nose gear bay itself by a good few inches, as shown here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z4kob.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z4kob.jpg&quot; alt=&quot;Eurofighter Typhoon Nose Gear Bay&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone shed any light on the reason for this gap?  It isn't a simple case of the aircraft in the photo having a maintenance issue, as this gap is consistent across all aircraft tranches and customers.&lt;/p&gt;&#xA;" OwnerUserId="11508" LastEditorUserId="22726" LastEditDate="2019-06-12T20:58:04.500" LastActivityDate="2019-06-12T20:58:04.500" Title="Why is the Eurofighter's nose gear door shorter than the bay?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="23210" PostTypeId="2" ParentId="23188" CreationDate="2015-11-27T12:00:22.317" Score="2" Body="&lt;p&gt;Quite often there is an air conditioning riser duct in the fuselage wall where there is a blank window space, due to the capacity requirement for the duct itself which is unable to fit between the windows.&lt;/p&gt;&#xA;" OwnerUserId="11508" LastActivityDate="2015-11-27T12:00:22.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23211" PostTypeId="2" ParentId="12460" CreationDate="2015-11-27T12:34:47.063" Score="0" Body="&lt;p&gt;For me the main part of this question is about the effect on wing lifting performance, not drag. I don't know the answer to this technically, but I could offer the following thoughts: The area taken by the wheels is a small percentage (perhaps 2-5% at a guess) of overall wing surface. Even on heavy aircraft, each square foot of wing only lifts a small amount of the overall weight of the aircraft. This is defined as an aircraft's wing loading see &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Wing_loading&lt;/a&gt; for more details. So even if putting the gear down totally destroyed the lift of that area of the wing (which it won't because its not like a hole in the wing - the wing is still there just not the optimal shape) it would only be like adding a few pounds in weight to the aircraft and having to fly at a slightly larger angle of attack as a result of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my conclusion is that the biggest affect of putting the gear down on any aircraft, is drag, the effect on lift will be minimal, and stall speeds are usually provided in the POH in landing configuration in any case. So this is not something a pilot would normally think about. The biggest deal for the pilot is the effect on the trim due to the position of the drag and the additional power needed to overcome the additional drag.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-11-27T12:34:47.063" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23212" PostTypeId="1" CreationDate="2015-11-27T13:07:35.727" Score="1" ViewCount="623" Body="&lt;p&gt;Jeppesen has made Electronic Flight Folders and seems to be a pioneer in that. Do they have any competitors for that?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="19" LastEditDate="2015-11-27T13:45:41.880" LastActivityDate="2015-11-29T20:13:06.197" Title="Are there competitors to Jeppesen making Electronic Flight Folders?" Tags="&lt;flight-planning&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2015-11-30T22:23:31.407" ContentLicense="CC BY-SA 3.0" />
  <row Id="23213" PostTypeId="2" ParentId="23212" CreationDate="2015-11-27T13:52:08.267" Score="0" Body="&lt;p&gt;From what I see, yes, there is a company called Flightman which also makes EFFs. I don't see any other companies listed that make them.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-11-27T13:52:08.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23214" PostTypeId="1" AcceptedAnswerId="23222" CreationDate="2015-11-27T14:18:39.007" Score="9" ViewCount="10249" Body="&lt;p&gt;At an airport with both runway and helipad (KASH) I have seen both being used for helicopter takeoffs and landings. Is there anything that causes the helicopter pilot to choose to use the runway instead of the helipad?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="19" LastEditDate="2017-02-23T10:57:46.607" LastActivityDate="2019-08-10T00:39:20.093" Title="When an airport has helipads, why would a helicopter take-off or land on a runway?" Tags="&lt;helicopter&gt;&lt;runways&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23215" PostTypeId="1" AcceptedAnswerId="23223" CreationDate="2015-11-27T14:30:11.477" Score="11" ViewCount="21772" Body="&lt;p&gt;Does anyone know why EasyJet uses &lt;strong&gt;U2&lt;/strong&gt; as the prefix for flight numbers? Other airlines have more logical prefixes. Eg. &lt;strong&gt;KL&lt;/strong&gt; -&gt; KLM, &lt;strong&gt;AZ&lt;/strong&gt; -&gt; Alitalia, &lt;strong&gt;BA&lt;/strong&gt;-&gt; British Airways, etc. Even though they do not always match the airline name exactly, they do mimic the name. &lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="3504" LastEditDate="2015-11-27T23:41:38.630" LastActivityDate="2020-02-13T16:40:15.120" Title="Is there a particular reason that EasyJet uses U2 as their code?" Tags="&lt;airline-operations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23217" PostTypeId="2" ParentId="23215" CreationDate="2015-11-27T15:07:03.950" Score="10" Body="&lt;p&gt;Easyjet got their IATA code fairly late on, and as such could not use EZ (which was in use by Sun Air), so they were randomly issued their IATA code of U2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They do have the three letter code of EZY, just as British Airways has BAW as well as BA.&lt;/p&gt;&#xA;" OwnerUserId="11508" LastActivityDate="2015-11-27T15:07:03.950" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23218" PostTypeId="2" ParentId="23214" CreationDate="2015-11-27T16:11:58.633" Score="2" Body="&lt;p&gt;My impression was that runway takeoffs are easier / safer because you remain less in the unsafe zone where auto-rotation is precluded. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. See the chart below. You want to avoid the red zone, the so called &quot;coffin corners&quot; (not to be confused with a similarly called but totally different operating envelope for Aircraft at high speeds). So airspeed helps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Tqw3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Tqw3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically auto-rotation is your safety pass in case of engine / transmission failure etc. So you want to avoid situations where you are gaining pure height without any airspeed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the recommended take off profile on the chart below. It increases airspeed a lot before the height increases significantly. That's what you get in a runway takeoff but I guess could also do in a helipad takeoff depending on the surrounding constraints on flight path.&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="22726" LastEditDate="2019-08-10T00:39:20.093" LastActivityDate="2019-08-10T00:39:20.093" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="23220" PostTypeId="2" ParentId="23214" CreationDate="2015-11-27T17:19:22.177" Score="0" Body="&lt;p&gt;Though I'm not sure of the exact circumstances, the helicopters may be carrying out a rolling take-off. This is done in some cases where sufficient power is not available for normal (hovering) takeoff, like high gross weight etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these cases, the helicopter is rolled down the runway to gain sufficient speed (to generate the required lift), so as to satisfy the power requirement. As this technique uses up considerable distance (for the takeoff roll and initial climb), and requires a smooth surface (during roll), the runway is preferred.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In case the helicopter had taken off from runway normally (i.e. in hover), the ATC might have asked the pilot to use the runway so as to let the other aircraft know which direction the helicopter is going.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-27T17:19:22.177" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23221" PostTypeId="2" ParentId="13150" CreationDate="2015-11-27T17:42:07.667" Score="1" Body="&lt;p&gt;I don't know if this is exactly the answer that you wanted but 5th Freedom Flights as they are called are airline and airport agreements that allow airlines to operate between two airports that aren't bases or focus cities. Examples could be Air France and KLM that operate from Jakarta and Singapore or Singapore Airlines that flies from Manchester to Munich and then onto Singapore. The only main requirement is that the flight must fly back to base. This is why usually long haul aircraft are required as the flight does fly back to the main base for the airline. Fifth freedom flights sell in either sector whether it is between the two non-base cities or between the base and another cities. This allows airlines to pick up more money and get more cash&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, long haul aircraft can be frequently used in Eastern Asia. For instance, flights from Osaka and Tokyo which is less than and hours journey can be served by 747's. The main problem with this is wear and tear this produces on the aircraft. This has caused accidents in the past due to metal fatigue and other dangers. &lt;/p&gt;&#xA;" OwnerUserId="12440" LastActivityDate="2015-11-27T17:42:07.667" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23222" PostTypeId="2" ParentId="23214" CreationDate="2015-11-27T18:13:57.453" Score="18" Body="&lt;p&gt;I know you asked specifically about runway versus helipad departures, but I thought I would lay out all the options available to the heli pilot, and you can see what all the choices are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three different areas on an airport that a helicopter can operate from:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Non-movement area -- this is the area of the airport that is not controlled by the ground or tower controller. It often consists of aircraft parking areas or an area leased by a tenant.  It is separated from a movement area by this the marking below. Helipads may be found in non-movement areas, such as the Coast Guard helipads at SFO and JFK.  &lt;a href=&quot;https://i.stack.imgur.com/sbjMc.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sbjMc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Movement area -- this is the area of the airport controlled by a ground controller, and separated from the runway area by this marking: &lt;a href=&quot;https://i.stack.imgur.com/iEsI5.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iEsI5.png&quot; alt=&quot;R&quot;&gt;&lt;/a&gt;. Helipads can be found in movement areas.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Runway area -- this is the area controlled by the tower controller, and contains the runways used for landing and departing traffic.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This picture from KHWD shows the three areas:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x8WIh.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x8WIh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of which area is used, almost heli departures from towered airports are coordinated directly with the tower controller because the aircraft enters the controllers airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At non-towered airports, helis operate out of the flow of fixed-wing traffic, and need to self-announce like any other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, helicopters can make three different kinds of departures:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;max performance take off -- which begins with a near-vertical segment, and then transitions to a horizontal. This is typically used from a confined area, and looks something like this: &lt;a href=&quot;https://i.stack.imgur.com/PfZ7O.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PfZ7O.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;normal takeoff -- this begins in an in-ground effect hover with a horizontal segment until translation lift is assured, then transitions into a climb: &lt;a href=&quot;https://i.stack.imgur.com/EIQe3.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EIQe3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;running takeoff -- when there is insufficient power to begin with an in-ground effect hover, then the helicopter may begin its departure by sliding (skids) or rolling (wheels) along the ground, until translational lift can be obtained, then transitioning into a normal takeoff: &lt;a href=&quot;https://i.stack.imgur.com/ytiuu.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ytiuu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The choice of departure area and departure type are for the most part independent, but they are obviously linked based on performance and obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The departure area is an &lt;em&gt;operational&lt;/em&gt; decision. When the helicopter is operating from a remote part of an airport, the pilot will often make a departure from a non-movement area (helipad or ramp) so she doesn't have to taxi to the runway.  If the helicopter is a passenger flight, such as air-taxi, it will most likely operate from the runway or a helipad in the movement area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The departure type is a &lt;em&gt;performance&lt;/em&gt; decision, based on obstacles, weather, weight, and available power. Hot &amp;amp; high departures might require a running take-off. Lightly loaded twin-engine copters in normal weather can safely make high-performance departures over obstacles in the desired direction of flight.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-11-27T19:16:03.687" LastActivityDate="2015-11-27T19:16:03.687" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23223" PostTypeId="2" ParentId="23215" CreationDate="2015-11-27T18:15:45.900" Score="8" Body="&lt;p&gt;EZY (EasyJet UK) code and EZS (EasyJet Switzerland)are the ICAO codes, whereas U2 is the code generated by IATA for them when they applied for an IATA code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.easyjet.com/ejcms/cache/medialibrary/files/travel%20agent%20online%20guides/en/amadeus&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.easyjet.com/ejcms/cache/medialibrary/files/travel%20agent%20online%20guides/en/amadeus&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EasyJet Airline Company Limited (UK Based)&lt;/strong&gt; - (IATA code: U2; ICAO code: EZY; Callsign: Easy) &#xA;&lt;strong&gt;EasyJet Switzerland SA&lt;/strong&gt; (IATA code: DS; ICAO code: EZS; Callsign: TOPSWISS) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ICAO codes are used for operational purposes like flight planning, ATC, etc. &lt;strong&gt;IATA codes like U2&lt;/strong&gt; are generally used in timetables, reservation systems, departure/arrival information, etc. - in other words information that is meant for the general public.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="11215" LastEditDate="2020-02-13T16:40:15.120" LastActivityDate="2020-02-13T16:40:15.120" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23224" PostTypeId="2" ParentId="23202" CreationDate="2015-11-27T19:09:06.343" Score="1" Body="&lt;p&gt;To track a course in a crosswind using the bug, set the OBS to the waypoint you wish to fly to and use your normal crabbing skills to track the needle (025 below). Once the needle is being tracked, you can set the heading bug to the current heading (015) and just fly that. This works with or without an autopilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Zlvxp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zlvxp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-11-27T19:19:14.413" LastActivityDate="2015-11-27T19:19:14.413" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23225" PostTypeId="2" ParentId="23176" CreationDate="2015-11-27T19:51:44.280" Score="0" Body="&lt;p&gt;Not sure what do you mean by &quot;metallic&quot;, but the sound of the Embraer ERJ-190 engines is quite different from the sound of larger engines, like those of A-320s or B737s...  I guess the fan does produce a much lower frequency sound due to much lower rotational speed.  And at full throttle, the 190's engines really do sound &quot;different&quot; compared to lower power settings.  I've even noticed some sort of buzzing cyclic variations, both in sound and some slight vibration too.  Let's not forget the Embraers are lighter in overall weight and construction, and their feel is indeed different.  Anyway, any prolonged contact between rotor and stator is not desirable or common.  There is a &quot;seal&quot; of the labyrinth type, but it is non-contacting.&lt;/p&gt;&#xA;" OwnerUserId="12442" LastEditorUserId="52" LastEditDate="2015-11-27T20:23:14.023" LastActivityDate="2015-11-27T20:23:14.023" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23226" PostTypeId="2" ParentId="23202" CreationDate="2015-11-27T21:07:30.113" Score="7" Body="&lt;p&gt;First thing first, let's go over some concept: &lt;strong&gt;heading&lt;/strong&gt; is which way the plane's nose is pointing at, &lt;strong&gt;track&lt;/strong&gt; is which way the plane is travelling on the ground. E.g. if your heading is 360 (North), and the wind is blowing from 090 (blowing East to West), the plane's track &lt;em&gt;may&lt;/em&gt; be 350 (slightly left of North).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in mind, it's not hard to deduce most of the time pilots want to fly &lt;em&gt;track&lt;/em&gt;, rather than &lt;em&gt;heading&lt;/em&gt;. The purpose is to navigate from point A to point B on the ground. In our example, you have to turn the plane slightly to the right to compensate for the crosswind. To figure out exactly how many degrees to turn, you will first need to decide how fast you want to fly. After that, it's simple geometry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5Q7Wr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Q7Wr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mechanical flight computer can be used to calculate the drift angle easily. Using it is a matter of marking dots on a transparent disc, then sliding and rotating it to the correct position and read off the pre-calculated figures below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CZ4Sy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CZ4Sy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If you are flying manually, or flying a plane with an elementary autopilot, you will need to calculate the drift angle, then add (or minus) that to your desired &lt;em&gt;track&lt;/em&gt; to get the &lt;em&gt;heading&lt;/em&gt;. You will then set the heading bug to that value. Theoretically, that heading should compensate just enough crosswind that you stay on your desired ground track. In practice minor adjustments are often necessary. Provided that the numbers you use are not awfully off, you should end up with an estimation good enough for the safety of your flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying a plane with an advanced flight computer which has the ability to detect winds aloft, your autopilot will fly the &lt;em&gt;track&lt;/em&gt; you dial in and automatically compensate for crosswind.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;So to answer your questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You will use simple math or tools to compute the heading which will let you fly the desired track.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It does not matter when you have an exact headwind or tailwind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Heading bug denotes the desired heading, not track. You always turn your plane towards the heading bug.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Advanced autopilot fly track, fundamental ones fly heading. Some autopilots can read the heading bug position on the instrument, others must be set explicitly on another panel.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2018-11-03T06:29:31.417" LastActivityDate="2018-11-03T06:29:31.417" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23227" PostTypeId="1" CreationDate="2015-11-27T22:14:06.497" Score="9" ViewCount="15474" Body="&lt;p&gt;I attend a Part 141 training school and have a total of 98.5 hours of flight training towards a commercial certificate, with 8 hours of simulator training, also for the commercial certificate. Can I count both the flight and the sim hours towards the aeronautical experience for the commercial certificate? It would be a lot cheaper and faster to reach the required 120 hours this way. The Beech Baron is not cheap to rent!&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="3504" LastEditDate="2015-11-30T13:43:10.180" LastActivityDate="2018-11-03T23:12:59.000" Title="Can I count simulator hours towards a commercial flight certificate training?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;flight-simulator&gt;&lt;far-141&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23228" PostTypeId="2" ParentId="23176" CreationDate="2015-11-27T23:14:41.620" Score="2" Body="&lt;p&gt;I &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/EASA-TCDS-E.021_(IM)_GE_CF34--10E_series_engines-05-03012013.pdf&quot; rel=&quot;nofollow&quot;&gt;found&lt;/a&gt; the following RPM limits for the GE CF34-10E: 6325 RPM and 18018 RPM for N1 and N2 stages. At 100% power, the RPM for the N2 stage is 17160 RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically we're looking at a rotational frequency of about 300 Hz. Well above the 20 Hz threshold for hearing, even if not at 100% power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where things get interesting is the fact that the human ear becomes markedly less sensitive to sounds below 300 Hz. So when the engine spins up from 200 Hz to 300 Hz, not only will the increased power probably produce more raw noise, it's also at a frequency that's more audible. But exactly &lt;em&gt;how&lt;/em&gt; strong that effect is, is hard to describe. &lt;a href=&quot;https://en.wikipedia.org/wiki/A-weighting#B-.2C_C-.2C_D-_and_Z-weightings&quot; rel=&quot;nofollow&quot;&gt;There's even a standard for this, specifically aimed at airplane noises!&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2015-11-27T23:14:41.620" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23230" PostTypeId="2" ParentId="22456" CreationDate="2015-11-27T23:38:05.400" Score="0" Body="&lt;p&gt;Calculating the exact amount of fuel necessary to make a trip is an inexact science, for exactly the reasons you mentioned.  The reported range is calculated for an ideal trip. Your mileage may vary.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-11-27T23:38:05.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23231" PostTypeId="2" ParentId="23227" CreationDate="2015-11-28T00:29:22.153" Score="8" Body="&lt;p&gt;According to the FAA, yes you can count those hours, but they can only count for only&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Under FAR part 141:&lt;/p&gt;&#xA;&lt;p&gt;7 hours(35%) of 35 hours of flight training towards a private pilot certificate&lt;/p&gt;&#xA;&lt;p&gt;17 hours(50%) of 35 hours of flight training towards an instrument rating&lt;/p&gt;&#xA;&lt;p&gt;36 hours(30%) of 120 hours of flight training towards a commercial pilot certificate&lt;/p&gt;&#xA;&lt;p&gt;10.5 hours(30%) of 25 hours of flight training towards a multi-engine rating&lt;/p&gt;&#xA;&lt;p&gt;12.5 hours(50%) of 25 hours of flight training towards an ATP cerfificate&lt;/p&gt;&#xA;&lt;p&gt;2.5 hours(10%) of 25 hours of flight training towards a flight instructor certificate&lt;/p&gt;&#xA;&lt;p&gt;1.5 hours(10%) of 15 hours of flight training towards an instrument flight instructor rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.dctaviation.com/#!sim-faq/ccj4&quot; rel=&quot;noreferrer&quot;&gt;http://www.dctaviation.com/#!sim-faq/ccj4&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;From what I see, you can probably fill up your remaining hours with sim time because you only have a little over 20 hours left and you can have 28 more hours of sim time towards your certification.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-28T20:51:07.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23232" PostTypeId="2" ParentId="23227" CreationDate="2015-11-28T00:51:28.003" Score="2" Body="&lt;p&gt;You can count the hours for certification subject to certain limiations. According to Federal regulations, Title 14 → Chapter I → Subchapter H →&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&amp;amp;SID=a2502146981a8fd862f4315cb648f89b&amp;amp;ty=HTML&amp;amp;h=L&amp;amp;mc=true&amp;amp;r=PART&amp;amp;n=pt14.3.141#ap14.3.141_1101.d&quot; rel=&quot;nofollow noreferrer&quot;&gt;Appendix D to Part 141—Commercial Pilot Certification Course&lt;/a&gt;,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) Training in a flight simulator that meets the requirements of §141.41(a) of this part may be credited for a maximum of 30 percent of the total flight training hour requirements of the approved course, or of this section, whichever is less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As the commercial pilot certificate requires 120 hours of flight training, this works out to 36 hours.&lt;/p&gt;&#xA;&lt;p&gt;The simulators should be approved by the administrator. According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&amp;amp;SID=a1d648c7c748140e49e52f6c63b38ad0&amp;amp;ty=HTML&amp;amp;h=L&amp;amp;mc=true&amp;amp;r=PART&amp;amp;n=pt14.3.141#se14.3.141_141&quot; rel=&quot;nofollow noreferrer&quot;&gt;§141.41   Flight simulators, flight training devices, and training aids&lt;/a&gt;,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Flight simulators. Each flight simulator used to obtain flight training credit allowed for flight simulators in an approved pilot training course curriculum must—&lt;/p&gt;&#xA;&lt;p&gt;(1) Be a full-size aircraft cockpit replica of a specific type of aircraft, or make, model, and series of aircraft;&lt;/p&gt;&#xA;&lt;p&gt;(2) Include the hardware and software necessary to represent the aircraft in ground operations and flight operations;&lt;/p&gt;&#xA;&lt;p&gt;(3) Use a force cueing system that provides cues at least equivalent to those cues provided by a 3 degree freedom of motion system;&lt;/p&gt;&#xA;&lt;p&gt;(4) Use a visual system that provides at least a 45-degree horizontal field of view and a 30-degree vertical field of view simultaneously for each pilot; and&lt;/p&gt;&#xA;&lt;p&gt;(5) Have been evaluated, qualified, and approved by the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For other certification courses, the percentage of simulator time that can be credited vary. For Instrument Rating Course, it is 50%, while for Private Pilot Certification Course, it is 20%.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-28T01:00:17.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23233" PostTypeId="1" AcceptedAnswerId="23235" CreationDate="2015-11-28T02:01:14.610" Score="26" ViewCount="9240" Body="&lt;p&gt;I've noticed on most Boeing aircraft that there are small fins on the upper surface of many of their wings. They are about one inch high and maybe two inches long (it's difficult to judge size from inside the passenger cabin without any reference) and spaced about a foot apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;noreferrer&quot;&gt;737&lt;/a&gt; there are eight of them spaced about a third of the way from the wing's root to its tip. On the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_757&quot; rel=&quot;noreferrer&quot;&gt;757&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;noreferrer&quot;&gt;777&lt;/a&gt; they are spaced out to almost the wing's tip, and I can't see them on any pictures of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;noreferrer&quot;&gt;747's&lt;/a&gt; wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a picture of them on the 737's wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E1Oeb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E1Oeb.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What purpose does these serve?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing I can think of is that they somehow discourage span-wise airflow, but they seem too small and short to accomplish much. The stall fences I've found in pictures via Google are all much larger and extend around and under the leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;OTOH, a diagram I found &lt;a href=&quot;http://navyflightmanuals.tpub.com/P-1231/P-12310053.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; suggests that they are placed at just about the place where the airflow turns span-wise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U7tDn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U7tDn.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They must serve some purpose.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastEditorUserId="849" LastEditDate="2015-11-29T14:34:02.140" LastActivityDate="2019-02-10T04:28:09.927" Title="What is the purpose of the small fins on top of the wing surface of Boeing aircraft?" Tags="&lt;wing&gt;&lt;boeing-737&gt;&lt;boeing-777&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23234" PostTypeId="2" ParentId="23233" CreationDate="2015-11-28T02:25:28.680" Score="23" Body="&lt;p&gt;They are vortex generators, used to delay flow separation. These vortex generators are usually attached near the leading edge of the wing and create small vortices, that prevent flow separation at high angles of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vnfkr.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vnfkr.gif&quot; alt=&quot;Vortex generators&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from microaero.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During normal flight, the airflow is accelerated over the wing, producing lift. At this point, the airflow is attached to the upper surface. However, the airflow loses its adherence and separates from the wing, aircraft performance can suffer in the form of increased drag, loss of lift and higher fuel consumption. The vortex generators act by 'mixing' the air in boundary layer with free stream air (through the vortices), thereby preventing the flow separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of Boeing aircraft use them. The following figure shows the vortex generators (32 no.s) used in 777 and 777 PIP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bb1pV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bb1pV.png&quot; alt=&quot;777 Vortex generator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortex generators in 777 and 777 PIP. Image from Boeing AERO qtr_03 | 09&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For swept wing aircraft, there is also a spanwise flow along the wing from the center toward the tips, in addition to the flow in direction of flight. This causes the boundary layer to thicken towards the tips, making them more susceptible to stalling than the wing root. As the ailerons are near the tips, this will make the ailerons lose control and create a pitch up moment (as it is usually aft of cg), which further exacerbates the problem, causing the whole wing to stall (due to increased angle of attack).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For preventing spanwise flow, wing fences are used, which are different from these. For example, the MiG-17 had prominent wing fences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1rNi6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1rNi6.jpg&quot; alt=&quot;Mig 17&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MiG-17F_Top_View.JPG#/media/File:MiG-17F_Top_View.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;MiG-17F Top View&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Rklawton&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Rklawton&quot;&gt;Robert Lawton&lt;/a&gt; - &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Rklawton&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Rklawton&quot;&gt;Robert Lawton&lt;/a&gt;. Licensed under CC BY-SA 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The function of both vortex generators and wing fences are the same (to prevent flow separation at high angles of attack); however, they go about it in different ways - vortex generators by creating vortices that prevent the boundary layer from separating, and wing fences by preventing cross flow by creating a boundary condition through the fences.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-02-10T04:28:09.927" LastActivityDate="2019-02-10T04:28:09.927" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="23235" PostTypeId="2" ParentId="23233" CreationDate="2015-11-28T02:26:46.000" Score="29" Body="&lt;p&gt;They are called &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_generator&quot; rel=&quot;noreferrer&quot;&gt;vortex generator&lt;/a&gt;s, and their function is to create a small vortex which re-energizes the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boundary_layer&quot; rel=&quot;noreferrer&quot;&gt;boundary layer&lt;/a&gt;. Here is a better picture which also shows that their leading edge is swept like that of a delta wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LMGCf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LMGCf.jpg&quot; alt=&quot;Vortex generators on a T-45&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortex generators on a T-45 (picture &lt;a href=&quot;http://static1.1.sqspcdn.com/static/f/343804/11651677/1302399081197/T-45_Vortex_Generators_Up_Close.jpg?token=RHl0DEXHlFNOoqMHXCxUUT1NFkM%3D&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In essence, they are small wings which each create their own &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift/21071?s=1%7C0.2746#21071&quot;&gt;delta wing vortex&lt;/a&gt;. This vortex mixes fast-moving air from outside the boundary layer with the air close to the wing surface, which has been slowed down by friction. This helps&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;at low speed to delay flow separation at high angle of attack&lt;/li&gt;&#xA;&lt;li&gt;at high speed to avoid an oscillation of the shock position when the supersonic pocket of flow over the wing is decelerated in a shock which can cause &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=7%7C0.1016#5055&quot;&gt;local flow separation&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The diagram in your question about &quot;Leading edge vortexing&quot; is very misleading. Air does not flow like shown by those arrows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airfoil &lt;a href=&quot;https://aviation.stackexchange.com/questions/21664/how-complete-is-our-understanding-of-lift/21685#21685&quot;&gt;initially accelerates the air which flows over its top surface and decelerates it again over its rear part&lt;/a&gt;. On swept wings, this acceleration-deceleration only affects the orthogonal speed component, so the speed component in span direction remains unaffected. This is the reason for the higher Mach capability of swept wings, but also causes the air to flow first inwards and then outwards while transversing the wing's upper surface. The diagram shows no such inward flow, which is wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, friction decelerates the air flowing around a body, such that a layer of decelerated air surrounds each surface of an airplane. The thickness of this boundary layer increases with flow length, and on a swept wing this friction will initially mostly affect the orthogonal flow component. At around mid chord you will find air which has been decelerated mostly in its orthogonal speed component (since this component was so high over the forward part) and now will be subject to more deceleration of the orthogonal component, so that only the spanwise component will be left over the rear part of the boundary layer. Now this boundary layer will only flow off in span direction, such that a massive increase of slow, low-energy air will be collecting towards the tips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A thick boundary layer will &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=7%7C0.1517#5055&quot;&gt;cause early flow separation&lt;/a&gt;, so when the angle of attack is increased, the flow at the tips of a backward swept wing will separate first. This will cause lift loss, and since the tips are also the rearward part of the wing, will shift the aerodynamic center forward. This in turn will make the aircraft pitch up, which aggravates the stall condition. If the separation happens asymmetrically, the aircraft will roll in addition to pitching up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both vortex generators and wing fences help to reduce this cross flow and delay flow separation on the outer wing at high angle of attack. Vortex generators also help to prevent boundary layer separation past a shock at transsonic speeds when placed close to the leading edge, something a wing fence is incapable of. Therefore, they are more helpful and have displaced wing fences on many swept wings.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-11-29T06:09:42.247" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23236" PostTypeId="2" ParentId="22589" CreationDate="2015-11-28T11:48:42.087" Score="9" Body="&lt;p&gt;To understand that particular design decision, some background may be necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1920s, Willy Messerschmitt had started a small aircraft factory in Bamberg with limited economical success. When he requested financial help from the Bavarian state, he was forced to merge with another aircraft factory in Augsburg, into &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt#Reestablishment&quot; rel=&quot;noreferrer&quot;&gt;Bayerische Flugzeugwerke&lt;/a&gt;. Since few of his designs enjoyed commercial success, he was forced to accept the production of other designs under license to keep the workforce of the combined companies occupied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only Messerschmitt design which had been accepted by Lufthansa was the &lt;a href=&quot;https://en.wikipedia.org/wiki/BFW_M.20&quot; rel=&quot;noreferrer&quot;&gt;M.20&lt;/a&gt;, and a close friend of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Erhard_Milch&quot; rel=&quot;noreferrer&quot;&gt;Lufthansa director&lt;/a&gt; was killed in a test flight of the M.20. When that director was promoted to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ministry_of_Aviation_(Nazi_Germany)&quot; rel=&quot;noreferrer&quot;&gt;German air ministry&lt;/a&gt; and became responsible for selecting aircraft for building up the new &lt;a href=&quot;https://en.wikipedia.org/wiki/Luftwaffe&quot; rel=&quot;noreferrer&quot;&gt;Luftwaffe&lt;/a&gt;, he made it clear to Messerschmitt that he would avoid purchasing his designs because he disapproved of his reaction to that fatal accident of the M.20.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Tl8Td.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tl8Td.jpg&quot; alt=&quot;Messerschmitt M.20&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Messerschmitt M.20 (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/BFW_M.20#/media/File:BFW_M-20_(1934).jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most successful type of Messerschmitt's designs was the &lt;a href=&quot;https://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%200333.html&quot; rel=&quot;noreferrer&quot;&gt;M.23&lt;/a&gt;, a two seater sports plane. It had suffered two accidents in which the tailplane broke off in flight, so struts for the tailplane were added while initially produced aircraft had an unbraced tail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5cp8W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5cp8W.jpg&quot; alt=&quot;Messerschmitt M.23&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early Messerschmitt M.23a with &lt;a href=&quot;https://en.wikipedia.org/wiki/ABC_Scorpion&quot; rel=&quot;noreferrer&quot;&gt;ABC Scorpion engine&lt;/a&gt; (picture &lt;a href=&quot;http://www.histaviation.com/Me_M_23a_with_ABC_Scorpion_engine.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Messerschmitt had gained a reputation for aerodynamically clean and very lightweight designs, &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B000O535TY&quot; rel=&quot;noreferrer&quot;&gt;and accidents of the M.20 and M.23 in which the tail section failed&lt;/a&gt; made pilots wary of the structural soundness of his designs. Nevertheless, his aircraft achieved surprising performance with very limited engine power, so he was unofficially asked to contribute a design when a competition for a new standard fighter was announced in 1934. As an outsider, he had to make sure that his design would be accepted by his critics, so he played it safe and braced the tail, as he had done on the M.37 (which was to become the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_108&quot; rel=&quot;noreferrer&quot;&gt;Bf-108&lt;/a&gt; and was in many ways the dress rehearsal to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_109#Origins&quot; rel=&quot;noreferrer&quot;&gt;Bf-109&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the real reason for the struts: Messerschmitt had to play it safe to not threaten his chances as an outsider for a very lucrative contract.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-11-28T20:58:10.293" LastActivityDate="2015-11-28T20:58:10.293" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23238" PostTypeId="1" AcceptedAnswerId="23240" CreationDate="2015-11-28T16:29:22.947" Score="4" ViewCount="4208" Body="&lt;p&gt;I'm doing a wind tunnel experiment and I'm trying to plot the pressure coefficient distribution for the upper and the lower surfaces of an airfoil based on experimental data. The airfoil chord is 150 mm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have the pressure static ports located at:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Upper static port #: 1    3    5     7     9     11    13    15     17     19&#xA;X-coord [mm]:        0.76 3.81 11.43 19.05 38.00 62.00 80.77 101.35 121.92 137.16&#xA;&#xA;Lower static port #: 2    4    6     8     10    12    14    16    18     20&#xA;X-coord [mm]:        1.52 7.62 15.24 22.86 41.15 59.44 77.73 96.02 114.30 129.54&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;And the pressure readings for each static port are the following:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Static port #:     1      2      3      4      5      6      7      8      9     10    11     12     13    14     15     16    17   18     19     20&#xA;Pressure [kPa]:   -0.034 -0.113 -0.087 -0.172 -0.136 -0.168 -0.148 -0.17 -0.15 -0.156 -0.133 -0.15 -0.124 -0.139 -0.12 -0.13 -0.13 -0.13 -0.117 -0.12 &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I also have Pitot velocity reading: $U_\infty=12.26$ m/s, density: $\rho=1.225$ kg/$m^3$ and $p_\infty=101.3$ kPa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that to compute the pressure coefficient for each static port, I have to use:&#xA;$$c_p(x,z(x)) = \dfrac{p(x,z(x))-p_\infty}{1/2\cdot \rho_\infty \cdot U_\infty^2 }$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I coded a MATLAB script that allows me to compute this equation for the upper part of the airfoil using the odd static ports readings, and for the lower part of the airfoil by using the even static ports readings of pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I'm having two problems that are a bit strange, &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Pressure coefficient must be dimensionless. I have the pressure values in &quot;kPa&quot; and the problem is that if I convert them into &quot;Pa&quot; by multiplying a 1000 factor. The pressure coefficients values will not be around 1, which is what I'm used to seeing in the Cp-chord graphs. How can I fix this? I'm not sure it's correct to use a dividing 1000 factor to compensate this effect.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When I plot the the result I obtain the following result, which is not very similar to the typical Cp-chord plots I have seen in experiments. Am I doing something wrong? Or is it a problem of the experiment in which I obtained bad data?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/exjLW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/exjLW.png&quot; alt=&quot;Cp vs. Chord&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could you help me solve my doubts by giving me a little help based on your experience? I'm not asking to get the problem solved, I just want to know how to do it properly.&lt;/p&gt;&#xA;" OwnerUserId="4358" LastEditorUserId="19" LastEditDate="2017-01-24T10:10:10.047" LastActivityDate="2017-01-24T10:10:10.047" Title="How should the pressure coefficient distribution from a wind tunnel experiment be interpreted?" Tags="&lt;aerodynamics&gt;&lt;wind-tunnel&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23239" PostTypeId="1" AcceptedAnswerId="23242" CreationDate="2015-11-28T20:30:16.297" Score="5" ViewCount="1566" Body="&lt;p&gt;This question may sound rhetorical or not well posed, but I wonder what the economic viability or sustainability of certain Emirates routes is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among its 164 destinations, Emirates is currently serving a whole host of non-major airports (airports which, according to &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_the_world%27s_busiest_airports_by_passenger_traffic#2015_statistics&quot; rel=&quot;nofollow&quot;&gt;this list&lt;/a&gt;, are not among the 30 busiest in the World). Among them are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Newcastle upon Tyne (NCL)&lt;/li&gt;&#xA;&lt;li&gt;Prague (PRG)&lt;/li&gt;&#xA;&lt;li&gt;Bologna (BLQ)&lt;/li&gt;&#xA;&lt;li&gt;Harare (HRE)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and so forth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question:&lt;/strong&gt; on the majority of these routes, a Boeing 777 is deployed. But how economically viable could it be to fly such a high-capacity plane to destinations where the target market is not so wealthy or not big enough? In some of these instances, Emirates is the sole airline operating the Boeing 777. Also, I speculate that other airlines would probably use another, smaller aircraft to some of these destinations. I am sure Emirates does its market researches with adequate meticulousness before opening any new route, but I am still doubtful - couldn't the people living around Bologna take a train to Milan to get to Dubai, for instance, &lt;a href=&quot;https://www.google.it/maps/dir/Bologna/Milan,+MI/@44.0344603,10.50582,6z/data=!4m14!4m13!1m5!1m1!1s0x477fd498e951c40b:0xa2e17c015ba49441!2m2!1d11.3426163!2d44.494887!1m5!1m1!1s0x4786c1493f1275e7:0x3cffcd13c6740e8d!2m2!1d9.1859243!2d45.4654219!3e3&quot; rel=&quot;nofollow&quot;&gt;given their close proximity&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="167" LastEditDate="2015-12-02T01:09:20.167" LastActivityDate="2017-05-15T09:26:00.163" Title="Is it economically viable for Emirates to use a 777 for some of these routes?" Tags="&lt;airline-operations&gt;&lt;boeing-777&gt;&lt;flight-path&gt;" AnswerCount="8" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23240" PostTypeId="2" ParentId="23238" CreationDate="2015-11-28T20:54:26.090" Score="4" Body="&lt;p&gt;First, your pressure values cannot be the measured pressure, because they are negative. This indicates that they are pressure differences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, their magnitude is too low to be in Kilopascal. Could it be that you list already the pressure coefficient?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, when plotting the pressure coefficient, it is customary to invert the Y axis, so the most negative value is on top. This just makes the plot look more familiar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I do this with the tabulated values, this is what I get:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2gIFH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2gIFH.png&quot; alt=&quot;Plot of tabulated values&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plot of tabulated values (own work). I extended the Y axis down to +1 on purpose, because this is the stagnation pressure coefficient in in compressible flow. Your data looks like that of a very thin symmetrical airfoil at an angle of attack near 0°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now look at this computed plot of pressure coefficients of symmetrical airfoils at zero angle of attack (&lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/SubsonicAirfoilsPres.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i4ECm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i4ECm.png&quot; alt=&quot;Inviscid pressure distribution of symmetrical NACA airfoils&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inviscid pressure distribution of symmetrical NACA airfoils. The black line looks like your data. Unfortunately you never mentioned which airfoil the measurement is from, but to me it looks awfully like a NACA&amp;nbsp;0006 (or even something thinner).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-11-28T20:54:26.090" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23241" PostTypeId="2" ParentId="22542" CreationDate="2015-11-28T22:38:15.247" Score="5" Body="&lt;p&gt;ACARS, otherwise known as Aircraft Communications and Addressing Reporting System, is almost always interfaced with the #3 VHF Communication System. Ordinarily, that #3 VHF system is set for &quot;Data Mode.&quot; Some aircraft have the ability to use the #3 VHF as an auxiliary communications system by putting it in voice mode, and other aircraft dedicate it to strictly data mode. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I have seen operators tie the ACARS system to the #2 VHF system when there is no #3 VHF system installed. In this case, it's ordinarily up to the pilots to switch between voice and data mode on the #2 VHF system. I can only imagine how annoying that must be!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While VHF is most frequently used on domestic flights, its relatively short range does little good on international flights over water. On aircraft meant for such long hauls, the ACARS system is usually tied to the HF radios and the SATCOM system. If I recall correctly, the ACARS system opts for VHF communications as the primary method. If there is no VHF available, or its rendered inoperative, the secondary method is often SATCOM; failing that, the HF systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for the aircrew to interface with the ACARS system, there is some sort of display with a keypad they interface with. On the vast majority of aircraft I've worked on, that display is often referred to as either the MCDU or CDU. On aircraft with MCDU's (Multifunction Control Display Unit), the pilot can select the mode they prefer to be in (ACARS, FMS, etc...), and can interface with the appropriate system through that singular central display - kind of like selecting what program you'd like to run on your computer. If the pilot selects ACARS, they can interface with all the relevant data pertinent to the ACARS system. If they select FMS, they can interface with the FMS (Flight Management System); and so on and so forth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On aircraft equipped with CDU's (Control Display Units), usually there are completely separate displays/interfaces for the FMS and ACARS. In that case, there are a plethora of options from a number of different manufacturers. I've seen touch screens, a secondary but different style CDU dedicated to ACARS communications, and so on and so forth. It's wide and varied. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MCDU and/or CDU usually interfaces with an ACARS Management Unit. That management unit is ordinarily the &quot;brain&quot; of the ACARS system. All pilot interactions with the MCDU/CDU are sent to the ACARS system, usually via a 429 Databus. The best way to think of this is that the MCDU/CDU setup is like your computer monitor and keyboard. You input data and see those inputs with keyboard and monitor, but the real &quot;action&quot; is taking place with the memory and processor &quot;behind the scenes.&quot; That behind the scenes action is the ACARS Management Unit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ACARS Management Unit (MU) can then interface with a variety of other systems and subsystems largely based on operator configuration. Some operators choose to log crew hours with the use of OOOI (Out, Off, On, In) times based on subsystem inputs to the ACARS MU. For example, when the beacon turns on, an input to the ACARS MU generates the &quot;Out&quot; time. When the aircraft takes off, the ground sensing mechanism of the aircraft sends a separate signal to the MU letting it know that the aircraft has left the ground. When that ground sensing mechanism changes state again (aircraft lands), it sends another signal to the MU letting it know that the aircraft has landed. Finally, when one of the doors (usually the L1 door) is opened after flight, the ACARS receives a signal from the door switch, and the &quot;In&quot; time is generated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes the MU is tied to an ACARS Aircraft Personality Module (APM). This is usually just a separate unit with DIP switches set to a certain configuration so no matter what MU is installed on a particular aircraft, it can pick up the &quot;correct identity&quot; and act accordingly. Other times, there is no APM and the configuration control is handled exclusively by the software load often verified by the mechanic after installation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, with the advent and implementation of ADS-B aircraft, GPS position data has begun to tie in to the ACARS system. If you want to see a mechanic roll his eyes, ask him to do a full functional check of the ADS-B system in the rain or cold. It's hours long, it never fails, and the consequences of what happens if it is failed are negligible. Most of us see it as a giant waste of time... But I digress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I'd like to note that all of this information is with the caveat that every operator is different, and so is every aircraft. There are endless combinations of systems that could or could not be tied into the ACARS system. Generally speaking, though, what I've mentioned above is a fairly standard installation. &lt;/p&gt;&#xA;" OwnerUserId="12452" LastActivityDate="2015-11-28T22:38:15.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23242" PostTypeId="2" ParentId="23239" CreationDate="2015-11-29T00:24:21.653" Score="9" Body="&lt;p&gt;There are many reasons an airline may fly to a given destination and the economics of air travel are complex to say the least. I would like to fist address your question &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;couldn't the people living around Bologna take a train to Milan to get&#xA;  to Dubai&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sure they could but airlines don't only service locations because of the people that live there they may service them for the very people that don't. I fly both commercially and as a GA pilot to explore new places. I generally fly out of the Philadelphia area which is one of the busiest in the US. From there I head to plenty of tiny airstrips all over the place, none of these airstrips are in towns that are as economically prosperous or busy as Philadelphia but they see my travel because I wish to explore the area. The same goes for foreign airports, simply because a country is less economically prosperous or &quot;busy&quot; than another does not mean it has less to offer culturally and in fact may be a hot bed for tourism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have personally been to both Prague and Bologna and they are great cities both with large tourist markets. I can see it being very economical to fly a wide body airliner there full of tourists and maybe only a few locals. While layovers may attract the lower budget fliers there are plenty of people who prefer a direct flight for both the convenience and time savings.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may be able to find more &lt;a href=&quot;https://www.iata.org/publications/economics/Pages/index.aspx&quot;&gt;stats here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-29T00:24:21.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23243" PostTypeId="1" CreationDate="2015-11-29T01:54:59.973" Score="2" ViewCount="596" Body="&lt;p&gt;Does the 300 hp conversion with a continental IO 550 always require an auxiliary tank when used on a Cessna 182?  I see some of these conversions indicate an auxiliary tank is present under pilot seat but I would like to try to avoid this.&lt;/p&gt;&#xA;" OwnerUserId="12454" LastEditorUserId="19" LastEditDate="2016-07-11T14:26:43.447" LastActivityDate="2016-07-11T14:26:43.447" Title="Does the 300 hp IO550 conversion require an auxiliary tank on the Cessna 182?" Tags="&lt;piston-engine&gt;&lt;fuel-tanks&gt;&lt;cessna-182&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23244" PostTypeId="2" ParentId="23243" CreationDate="2015-11-29T02:16:40.147" Score="2" Body="&lt;p&gt;I don't think so. The modification is done in accordance with &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0ahUKEwjv7Lf4xLTJAhXDwI4KHdjTD6sQFggcMAA&amp;amp;url=http%3A%2F%2Fairplains.com%2Findex.php%2Fsupport%2Fdrawings-documents%2Fcategory%2F19-air-plains-cessna-182%3Fdownload%3D58%3A182023-continued-airworhiness&amp;amp;usg=AFQjCNEauqW5eMpPYACK-x6sIcEqv808hA&amp;amp;bvm=bv.108194040,d.c2E&amp;amp;cad=rja&quot; rel=&quot;nofollow&quot;&gt;AIR PLAINS STC SA00152WI&lt;/a&gt;, which has no mention of any auxiliary fuel tank in the 'parts installed' section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the document says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fuel flows by gravity from the wing tanks to a four position selector valve..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no mention of auxiliary fuel tank anywhere.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-29T02:16:40.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23245" PostTypeId="1" AcceptedAnswerId="23246" CreationDate="2015-11-29T02:29:45.873" Score="10" ViewCount="3178" Body="&lt;p&gt;I read that the Navy originally considered to use the ATF(Advanced Tactical Fighter) Programme aircraft (Now known as the F-22) as carrier aircraft but declined to do so when it came out. How feasible is it now to convert an F-22 to carrier use? (I kind of want to know because it is a better plane than the F-35 but is not used on carriers even though it was originally planed for)&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2015-11-30T22:22:32.160" LastActivityDate="2017-11-26T23:47:01.820" Title="What is the feasibility of converting an F-22 to carrier use?" Tags="&lt;military&gt;&lt;aircraft-carrier&gt;&lt;f-22&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23246" PostTypeId="2" ParentId="23245" CreationDate="2015-11-29T03:25:48.973" Score="17" Body="&lt;p&gt;In general, land based aircraft do not lend themselves well to carrier conversion. On the other hand, conversion in opposite direction is (relatively) easy, as shown by F-4 and F-18.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversion of aircraft to carrier use require a number of modifications:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Tail hook has to added and rear fuselage reinforced for arrested landings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Landing gear has to be strengthened for high sink rate (~24 ft/s).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Atleast in USN, the front landing gear and fuselage has to be strengthened for catapult launches.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, it requires additional equipment, like th Carrier Landing system, redesigned refueling system (pretty much everyone use a system different from USAF).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Carrier based aircraft usually are expected to have better low speed capabilities as they have to fly slower approaches and wave-off (go-around) at lower speed compared to the land based aircraft. This dictates the wing loading, resulting in increased wing area and/or high lift devices.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are also issues in corrosion prevention etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The weight penalty due to these reasons can be non negligible. For example, the naval Rafale M version weighs nearly 500 kg more than the Air Force Rafale C variant (which has ~10 ton empty weight). USN calculated that the NATF (Naval Advanced Tactical Fighter) will be around 1800 kg heavier than the Air force version (ATF was supposed to weigh ~15 ton).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is that the USAF and USN had different requirements, for example, the USAF wanting a single seater and USN wanting a double seater, requirement of different sensors (for fleet defence) etc. in the end, the aircraft proposed for the NATF looked nothing similar to the one that finally became the F-22 and the project was quietly buried.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LiOhg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LiOhg.jpg&quot; alt=&quot;NATF&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-22 NATF proposal, image from aerospaceweb.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the design has swing wings, as the aircraft was being proposed for replacing F-14 Tomcat. Another important result of the navalization of the aircraft is the reduction in the number of planform alignments, and their negative impact on the stealth characteristics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carrier conversion of F-22 could have been done if it was considered early in design. Doing it now (note that NATF was considered due to the insistence of Congress; it is doubtful if USN ever wanted it). Doing so later in the design process will result in another F-111B fiasco. As for doing it now, it is better to design a new aircraft (which was what the F-35 is).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-29T12:31:53.990" LastActivityDate="2015-11-29T12:31:53.990" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23248" PostTypeId="1" CreationDate="2015-11-29T05:56:26.040" Score="2" ViewCount="720" Body="&lt;p&gt;I'm concerned about safety rules for commercial flight in North America. There is supposed to be a fuel reserve of &quot;30 minutes&quot; if I remember correctly. This seems to imply an extra 30 minutes of flying time, but this is not perfectly clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, for example, does this 30 minutes include the worst case scenario of a headwind during the entire flight? If so, what is the max headwind speed used in the calculation?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="62" LastEditDate="2015-11-30T15:44:41.417" LastActivityDate="2015-11-30T15:44:41.417" Title="Do fuel reserves take into account the possibility of a constant headwind?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;commercial-aviation&gt;&lt;flight-planning&gt;&lt;fuel&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23249" PostTypeId="2" ParentId="23248" CreationDate="2015-11-29T06:19:59.627" Score="3" Body="&lt;p&gt;The &lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGFAR.NSF/0/1cc5b5dad63e4806852566ef006dd813!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;full regulation reads&lt;/a&gt; (S121.639) &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Fuel supply: All domestic operations.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;No person may dispatch or take off an airplane unless it has enough&#xA;  fuel-- &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) To fly to the airport to which it is dispatched; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Thereafter, to fly to and land at the most distant alternate airport&#xA;  (where required) for the airport to which dispatched; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption&#xA;  or, for certificate holders who are authorized to conduct day VFR&#xA;  operations in their operations specifications and who are operating&#xA;  nontransport category airplanes type certificated after December 31,&#xA;  1964, to fly for 30 minutes at normal cruising fuel consumption for&#xA;  day VFR operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Part a denotes that they must be able to fly to the airport to which they are dispatched. There is an implied assumption that this includes any and all headwinds in the calculations. Likewise part b requires them to land at the most distant alternate (where required) which would also imply headwinds are calculated for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough the part 91 regulations (non airline) do specifically state that winds must be accounted for, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel requirements for flight in VFR conditions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may begin a flight in an airplane under VFR conditions&#xA;  unless (considering wind and forecast weather conditions) there is&#xA;  enough fuel to fly to the first point of intended landing and,&#xA;  assuming normal cruising speed-- &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) During the day, to fly after that for at least 30 minutes; or &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) At night, to fly after that for at least 45 minutes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may begin a flight in a rotorcraft&#xA;  under VFR conditions unless (considering wind and forecast weather&#xA;  conditions) there is enough fuel to fly to the first point of intended&#xA;  landing and, assuming normal cruising speed, to fly after that for at&#xA;  least 20 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-29T06:19:59.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23250" PostTypeId="2" ParentId="23248" CreationDate="2015-11-29T06:23:08.827" Score="1" Body="&lt;p&gt;The required fuel reserve is for 45 minutes. According to 14 CFR 121 &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=fb7f730c6a5045b2b926424915f0fa69&amp;amp;mc=true&amp;amp;node=se14.3.121_1639&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§121.639   Fuel supply: All domestic operations&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No person may dispatch or take off an airplane unless it has enough fuel—&lt;/p&gt;&#xA;&lt;p&gt;(a) To fly to the airport to which it is dispatched;&lt;/p&gt;&#xA;&lt;p&gt;(b) Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and&lt;/p&gt;&#xA;&lt;p&gt;(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption or, for certificate holders who are authorized to conduct day VFR operations in their operations specifications and who are operating nontransport category airplanes type certificated after December 31, 1964, to fly for 30 minutes at normal cruising fuel consumption for day VFR operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The factors to be considered in calculating the fuel reserve include the winds. According to 14 CFR 121 &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=fb7f730c6a5045b2b926424915f0fa69&amp;amp;mc=true&amp;amp;node=se14.3.121_1647&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§121.647 Factors for computing fuel required&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Each person computing fuel required for the purposes of this subpart shall consider the following:&lt;/p&gt;&#xA;&lt;p&gt;(a) Wind and other weather conditions forecast.&lt;/p&gt;&#xA;&lt;p&gt;(b) Anticipated traffic delays.&lt;/p&gt;&#xA;&lt;p&gt;(c) One instrument approach and possible missed approach at destination.&lt;/p&gt;&#xA;&lt;p&gt;(d) Any other conditions that may delay landing of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This explicitly states that any headwind experienced now or is expected based on weather forecasts is to be included in calculating the fuel quantity required.&lt;/p&gt;&#xA;&lt;p&gt;Note that the ICAO annex 6, part I &lt;a href=&quot;http://code7700.com/pdfs/icao_annex_6_part_i.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;4.3.6&#xA;Fuel and oil supply &lt;/a&gt; calls for similar fuel reserves, stating,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A flight shall not be commenced unless, taking into account both the meteorological conditions and any delays that are expected in flight, the aeroplane carries sufficient fuel and oil to ensure that it can safely complete the flight. In addition, a reserve shall be carried to provide for contingencies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In all these cases, headwinds enter into calculation only if the the present weather conditions or forecasts indicate their presence. However, in general, the fuel reserve carried is generally more than the 45 minute reserve, for safety.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-11-29T06:51:01.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23251" PostTypeId="1" AcceptedAnswerId="23255" CreationDate="2015-11-29T10:51:30.473" Score="24" ViewCount="5169" Body="&lt;p&gt;I have explored many similar questions such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/15942/how-does-a-missile-lock-work&quot;&gt;How does a Missile Lock Work?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5026/how-is-a-missile-lock-detected&quot;&gt;How is a missile lock detected?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In reading there respective answers, I have learnt about the multitude of detection mechanisms employed, but one question lingers and remains unanswered:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;How would an aircraft differentiate between the multiple missile lock signals it would likely be receiving?&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In a dogfight scenario (although they can occur over a large distance) a single aircraft may well detect the signals emitted by either the missile as part of an &quot;Active Radar Homing&quot; mechanism, or from the launcher itself as part of &quot;Passive Radar Homing&quot;, regardless of whether the aircraft is the intended target, presumably causing every aircraft in the area to be notified to the single missile lock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't pretend to be well versed on the subject of aerial warfare, yet I consider it nonsensical that every aircraft in the engagement be notified to the missile lock of a single aircraft as it would distract the pilots, all of whom would be required to ensure that they are not the targets.&lt;/p&gt;&#xA;" OwnerUserId="12457" LastEditorUserId="22726" LastEditDate="2019-08-09T23:53:01.587" LastActivityDate="2019-08-09T23:53:01.587" Title="How do aircraft differentiate between missile locks?" Tags="&lt;military&gt;&lt;aircraft-systems&gt;&lt;dogfighting&gt;&lt;missile-lock&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="23252" PostTypeId="2" ParentId="4962" CreationDate="2015-11-29T11:02:43.177" Score="3" Body="&lt;p&gt;Decent aerodynamic (wind tunnel) data is available courtesy of NASA / NTRS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.zaretto.com/content/simulation-aerodata-downloads&quot; rel=&quot;nofollow&quot;&gt;Windtunnel derived aerodynamic data sources&lt;/a&gt; is where I have collected together detailed data for the B747, F-14 and F-15.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;B747 Aerodynamic data&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;NASA CR-1756 The Simulation of a Large Jet Transport Aircraft Volume I: Mathematical Model, C. Rodney Hanke&#xA;March 1971 &lt;/li&gt;&#xA;&lt;li&gt;D6-30643 THE SIMULATION OF A JUMBO JET TRANSPORT AIRCRAFT - VOLUME 11: MODELING DATA, C. Rodney Hanke and Donald R. Nordwall September 1970&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;F-14 Aerodynamic data&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These are the data sources for my &lt;a href=&quot;http://www.zaretto.com/f-14b&quot; rel=&quot;nofollow&quot;&gt;F-14 for FlightGear&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;F-14A Aerodata plots F-14A Aerodata plots from AFWAL-TR-80-3141. These are in the TR; and don't reflect the JSBSim model as that has more data; this is just what I made for reference whilst modelling.&#xA;Richard Harrison&lt;/li&gt;&#xA;&lt;li&gt;AFWAL-TR-80-3141, Part I Investigation of High-Angle-of-Attack Maneuver-limiting factors, Part I: Anaylsis and simulation&#xA;Donald E. Johnston, David G. Mitchell, Thomas T. Myers&#xA;1980&lt;/li&gt;&#xA;&lt;li&gt;AFWAL-TR-80-3141, Part III: Investigation of High-Angle-of-Attack Maneuver-limiting factors, Part III: Appendices aerodynamic models&#xA;Donald E. Johnston, David G. Mitchell, Thomas T. Myers&#xA;1980&lt;/li&gt;&#xA;&lt;li&gt;NASA TN D-6909 DYNAMIC STABILITY DERIVATIVES AT ANGLES OF ATTACK FROM -5deg TO 90deg FOR A VARIABLE-SWEEP FIGHTER CONFIGURATION WITH TWIN VERTICAL TAILS&#xA;Sue B. Grafton and Ernie L. Anglin&#xA;1972&lt;/li&gt;&#xA;&lt;li&gt;NASA-TM-101717 Flutter clearance to the F-14A Variable-Sweep Transition Flight Expirement Airplane - Phase 2&#xA;Lawrence C. Freudinger and Michael W. Kehoe&#xA;July 1990&lt;/li&gt;&#xA;&lt;li&gt;N89 - 20931 APPLIED TRANSONICS AT GRUMMAN&#xA;W. H. Davis&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;F-15 Aerodynamic data sources&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;These are the data sources / references for &lt;a href=&quot;http://www.zaretto.com/content/f-15-simulator-flightgear&quot; rel=&quot;nofollow&quot;&gt;F-15 for FlightGear&lt;/a&gt;. The FDM is based on the windtunnel derived aerodynamic data found in (AFIT/GAE/ENY/90D-16).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Richard Harrison, rjh@zaretto.com: F-15 Aerodynamic data from (AFIT/GAE/ENY/90D-16); CG 25.65%, ZDAT/AED/2014/12-2, December, 2014: F-15 Aerodynamic data extracted from AFIT/GAE/ENY/90D-16&lt;/li&gt;&#xA;&lt;li&gt;Robert J. McDonnell, B.S., Captain, USAF: INVESTIGATION OF THE HIGH ANGLE OF ATTACK DYNAMICS OF THE F-15B USING BIFURCATION ANALYSIS, AFIT/GAE/ENY/90D-16, December 1990: ADA230462.pdf&lt;/li&gt;&#xA;&lt;li&gt;Richard L. Bennet, Major, USAF: ANALYSIS OF THE EFFECTS OF REMOVING NOSE BALLAST FROM THE F-15 EAGLE, AFIT/GA/ENY/91D-1, December 1991: ADA244044.pdf&#xA;DR. J. R. LUMMUS, G. T. JOYCE, O C. D. O MALLEY: ANALYSIS OF WIND TUNNEL TEST RESULTS FOR A 9.39-PER CENT SCALE MODEL OF A VSTOL FIGHTER/ATTACK AIRCRAFT : VOLUME I - STUDY OVERVIEW, NASA CR-152391-VOL-1 Figure 3-2 p54, October 1980: 19810014497.pdf&lt;/li&gt;&#xA;&lt;li&gt;Frank W. Burcham, Jr., Trindel A. Maine, C. Gordon Fullerton, and Lannie Dean Webb: Development and Flight Evaluation of an Emergency Digital Flight Control System Using Only Engine Thrust on an F-15 Airplane, NASA TP-3627, September 1996: 88414main_H-2048.pdf&lt;/li&gt;&#xA;&lt;li&gt;Thomas R. Sisk and Neil W. Matheny: Precision Controllability of the F-15 Airplane, NASA-TM-72861, May 1979 87906main_H-1073.pdf&#xA;Aircraft handling data&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;NT-a3A, F-104A, F-4C, X-15, HL-10, Jetstar, CV-880M, B-747, C-5A, and XB-70A.&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Robert K. Heffley and Wayne F. Jewell, NASA CR-2144 AIRCRAFT HANDLING QUALITIES DATA,&#xA;December 1972&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;JSBSim implementations of the aerodynamics models can be viewed in my GitHub repository &lt;a href=&quot;https://github.com/Zaretto/fg-aircraft/blob/flightgear-release/aircraft/f-14b/f-14a.xml&quot; rel=&quot;nofollow&quot;&gt;F-14&lt;/a&gt; and &lt;a href=&quot;https://github.com/Zaretto/fg-aircraft/blob/flightgear-release/aircraft/F-15/f15a.xml&quot; rel=&quot;nofollow&quot;&gt;F-15&lt;/a&gt;. These are both useful references in how to implement an aerodynamic model using JSBSim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where no such data is available &lt;a href=&quot;http://www.openvsp.org/&quot; rel=&quot;nofollow&quot;&gt;OpenVSP&lt;/a&gt; using &lt;a href=&quot;http://www.openvsp.org/wiki/doku.php?id=vspaerotutorial&quot; rel=&quot;nofollow&quot;&gt;VSPAero&lt;/a&gt; is a useful tool for generating coefficients from geometry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any computational method (including OpenVSP and X-Plane) will not be able to attain the accuracy gained from windtunnel measurements, especially as you reach the edge of the flight envelope. All FAA Level D simulators use wind tunnel derived aerodyanmic data packages for this reason.&lt;/p&gt;&#xA;" OwnerUserId="2403" LastEditorUserId="2403" LastEditDate="2015-11-29T11:08:35.353" LastActivityDate="2015-11-29T11:08:35.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23253" PostTypeId="2" ParentId="23248" CreationDate="2015-11-29T11:26:24.423" Score="4" Body="&lt;p&gt;The fuel &quot;to reach the destination&quot; is computed using winds, head- or tail-wind as appropriate. For &quot;30 minutes of reserve&quot; that is 30 minutes, and it is the same 30 minutes regardless of flying into or with the wind. In 30 minutes of flying with a tailwind you'll fly FARTHER than 30 minutes with a headwind, but 30 minutes is 30 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;-- Edit to answer the question as expanded in a comment:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind predictions are actually pretty good now, and &quot;30 minutes&quot; isn't really all that the pilot has to work with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For FAR Part 91, essentially general aviation (think taking a Cessna on a flight of a few hundred miles as an easy picture), the legal minimum in good weather is 30 minutes.  For FAR Part 121, which governs airline flying, it's 45 minutes (plus other categories as explained in the other answers for things like a destination alternate).  Beyond that, the plan for the flight will almost always include additional fuel above that to account for the routine things that happen to burn more gas: delays waiting to take off, small changes in routing that add a few miles to the planned path, and so on.  That way, even with the routine &quot;stuff&quot; that happens, you don't plan to eat into the 45 minutes reserve.  If the wind forecast is off, then that tends to be another of &quot;those things&quot; that changes the plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Realistically, how much are the winds off of the forecasts?  Typically, the forecasts are pretty close.  The computer models that are used now are very detailed, which is possible with all the computing power that's available now as compared to a decade or two ago.  Also, these models are constantly updated by data coming in from aircraft that are airborne.  Various datalinks can transmit the winds and temperature in real time, and ATC will also sometimes ask for current winds at a particular altitude.  All of this combines to give a picture that isn't simply a wind forecast issued in isolation, but a combination of forecast + recent data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue that would arise if an airline were required to plan on the worst-case wind that &lt;em&gt;might&lt;/em&gt; be encountered as if it would be present for the entire flight, is that in some cases the flight would significantly under-burn: it would arrive with more fuel than planned.  Why is that an issue?  Maximum Landing Weight.  If your airliner is fully loaded with passengers &amp;amp; cargo, there is a limit to how much fuel it can have on board at landing, driven by the maximum certified landing weight.  On my airplane, that tends to be enough fuel for a bit over two hours of flying.  (Obviously a LOT of factors influence this on each flight -- this is a ballpark number.)  So if I have a full airplane and I want to plan on having as much fuel as possible upon arrival (so that we can hold if necessary, fly the approach, and still have adequate fuel for a missed approach and then a divert, arriving at the alternate with adequate margins), there is a limit to how much I can take off with.  And that limit is driven by how much fuel we're expected to burn enroute.  If my enroute burn is lower than planned and I do NOT have to hold or take a longer route than planned, I can show up too heavy to legally land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two options when that happens: land anyway (safe, but requires an inspection of the aircraft, and it's generally frowned upon to do this without good reason), or fly circles to burn off the gas.  The latter is what is generally done, and is obviously wasteful.  So it's preferred that the enroute burn calculations be as accurate as possible, rather than including unrealistic headwind values.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-11-29T22:40:38.183" LastActivityDate="2015-11-29T22:40:38.183" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23254" PostTypeId="1" AcceptedAnswerId="23257" CreationDate="2015-11-29T12:23:25.633" Score="5" ViewCount="6857" Body="&lt;p&gt;I hope this is not as trivial as it sounds. Is there a wind gusts threshold based on which, at a given airport, incoming flights are diverted and outgoing ones are delayed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that aircraft are designed to handle a specific maximum wind gust, so if there is any such threshold, I expect it to be less than the design threshold. Is this correct?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="3827" LastEditDate="2015-11-29T21:07:17.490" LastActivityDate="2015-11-29T22:35:36.483" Title="How strong must wind gusts be to prevent landings and takeoffs?" Tags="&lt;aircraft-design&gt;&lt;wind&gt;&lt;crosswind&gt;&lt;windshear&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23255" PostTypeId="2" ParentId="23251" CreationDate="2015-11-29T12:46:33.830" Score="32" Body="&lt;p&gt;Non-holographic radar systems such as those used in fighter aircraft and active guided missiles only point in one direction at a time. Normally, when the radar is in &lt;em&gt;search&lt;/em&gt; mode, a mechanism inside the radar makes the beam move from side to side (possibly up and down as well), so it has a wider field of view and can pinpoint the direction of any aircraft it finds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft with the radar warning receiver (RWR) sees a brief pulse of radiation every second or so: only when the beam is pointing in its direction. This way, it knows the radar emitter is in search mode, and the direction of the emitter. Every aircraft in the radar's field of view will see the beam at different times, and they will all see the radar on their RWR screens. In a combat zone this is potentially a lot of emitters, but the RWR can analyse the radar signal to identify the radar: what type of aircraft, SAM, or ground radar it is, and whether it's friendly or enemy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting the position of the target only every second isn't good enough to guide a missile towards it. When the radar is in &lt;em&gt;track&lt;/em&gt; or &lt;em&gt;launch&lt;/em&gt; mode, it stops scanning the beam, and keeps it pointed at the target aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RWR on the target aircraft now sees much faster pulses of radiation, so it knows that it is the sole target of the radar. At this time, it can warn the pilot of a missile lock. But because the radar is now only pointing in this one direction, other aircraft in the area don't get illuminated by radar at all. Their RWR systems won't pick anything up. Only the aircraft that's actually threatened gets the missile lock warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, the same analysis that can identify what type of radar is illuminating the aircraft can also identify fully active radar-guided missiles. Like when the aircraft's radar is in &lt;em&gt;track&lt;/em&gt; or &lt;em&gt;launch&lt;/em&gt; mode, the missile's radar emitter only points in one direction, and doesn't scan, so only the target aircraft will see it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Obviously it's a little bit more complicated than this. There are a lot of details about how frequent the radar pulses are, and how the RWR knows the range of the source, but I hope I've captured all the important information in an understandable way.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-11-29T12:46:33.830" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23256" PostTypeId="2" ParentId="23251" CreationDate="2015-11-29T12:47:43.397" Score="14" Body="&lt;p&gt;In short, the onboard Radar Warning System computer analyzes the data and determines whether the missile has locked onto the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, aerial warfare is very complex and it is very difficult to explain in the real situations. Basically, the radars use different modes while engaging aircraft (from other aircraft or ground based SAM batteries):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;First, the &lt;em&gt;scan&lt;/em&gt; the area for any threats.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Once any threats are detected, they &lt;em&gt;track&lt;/em&gt; the threats.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Once the threat is tracked, it is prioritized and the radar/missile &lt;em&gt;locks&lt;/em&gt; onto the target.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Radars can change either the frequency or the strength between these modes. For tracking a target, the radar is basically scanning a smaller portion with higher intensity to get more resolution. So, the radar signals will be stronger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, consider the dogfight scenario you mentioned; every radar in the area will be emitting electromagnetic radiation and get the returns from &lt;em&gt;all&lt;/em&gt; the radars in the area. This is, to put it mildly, confusing. So the radars adjust the frequencies so that they have different values and track the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the RWR uses these two information to differentiate between the various radars. By looking at the frequencies/strength and comparing it with the available onboard library, it can determine which radar is emitting in which mode. In fact, creating this library is (one of) the most difficult things in design of ECM systems, which is the reason why everyone is trying to 'probe' other's defences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image shows a typical RWR display, where the threats and their locations are shown. The stronger the radar signal is, (probably) the closer is the radar source and more imminent is the threat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fRN1f.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fRN1f.png&quot; alt=&quot;RWR display&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical RWR display, from &lt;a href=&quot;http://gizmodo.com/how-fighter-jets-lock-on-and-how-the-targets-know-1644871272&quot; rel=&quot;noreferrer&quot;&gt;gizmodo.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This display shows an F-15 at the 7-o'clock position and two surface-to-air missile (SAM) sites, an SA-5 &quot;Gammon&quot; and an SA-6 &quot;Gainful&quot;, at the 12- to 1-o'clock position. The RWR computer has determined the SA-6 to be the highest priority threat in the area, enclosing it with a diamond.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other ways to determine of the missile is locked on the aircraft: you can use a doppler radar to track the missile and calculate the intended trajectory. However, this means exposing the aircraft to the radars in the first place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the onboard computer analyzes the data and determines the the threat and severity, it alerts the pilot, usually by changing the display and in some cases, by audible alerts. In such cases, the pilot can release the countermeasures or the system can do so automatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the real situation will be much more complex with all the countermeasures, ECMs and ECCMs etc. But this should give a basic picture of the situation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="753" LastEditDate="2015-11-29T16:15:09.467" LastActivityDate="2015-11-29T16:15:09.467" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23257" PostTypeId="2" ParentId="23254" CreationDate="2015-11-29T13:16:53.560" Score="9" Body="&lt;p&gt;You have two questions here, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I hope this is not as trivial as it sounds. Is there a wind gusts&#xA;  threshold based on which, at a given airport, incoming flights are&#xA;  diverted and outgoing ones are delayed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As far as I know there is no specific threshold for which they will divert. You may want to read up on &lt;a href=&quot;https://aviation.stackexchange.com/questions/22978/what-wind-change-gradient-is-necessary-to-be-classified-as-wind-shear&quot;&gt;wind shear here&lt;/a&gt; as an airport may advise sever or unsafe wind shear and urge pilots to divert. There will be a point (often at single runway airports) where a landing in a particular type of aircraft becomes unsafe or even impossible as a result of wind but this will vary by plane.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also, I assume that aircraft are designed according to a specific max&#xA;  wind gust, so if there is any wind gusts threshold, I expect it to be&#xA;  less than the design threshold. Is this correct?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, aircraft are designed with whats called a &lt;a href=&quot;https://aviation.stackexchange.com/questions/201/what-is-a-demonstrated-crosswind-component&quot;&gt;maximum demonstrated crosswind component&lt;/a&gt;. The key here is that this is a &lt;em&gt;demonstrated&lt;/em&gt; limit not necessarily an airframe limitation. The number is &lt;a href=&quot;http://www.aopa.org/asf/publications/inst_reports2.cfm?article=3651&quot; rel=&quot;nofollow noreferrer&quot;&gt;published in the POH for the aircraft made after 1975&lt;/a&gt; and provides a general guideline of the maximum cross wind the plane can be landed safely in however its more than possible to land it in higher wind situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also it should be noted that some of this is up to the pilot in command. Just because a towered airport clears you to land does not mean it is safe for you to do so likewise just because a pilot diverts does not mean they were instructed to do so by the tower they may self elect based on their personal abilities. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-11-29T22:34:01.217" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23258" PostTypeId="2" ParentId="23254" CreationDate="2015-11-29T13:18:05.987" Score="7" Body="&lt;p&gt;The maxima of wind gusts which need to be considered in the structural design of aircraft to achieve certification are up- or downdrafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.11#se14.1.25_1341&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR part 25.341&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The following reference gust velocities apply: &lt;/p&gt; &lt;p&gt;(i) At airplane speeds between V$_B$ and V$_C$: Positive and negative gusts with reference&#xA;  gust velocities of 56.0 ft/sec EAS must be considered at sea level.&#xA;  The reference gust velocity may be reduced linearly from 56.0 ft/sec&#xA;  EAS at sea level to 44.0 ft/sec EAS at 15000 feet. The reference gust&#xA;  velocity may be further reduced linearly from 44.0 ft/sec EAS at 15000&#xA;  feet to 26.0 ft/sec EAS at 50000 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since wind rarely flows into or out of the ground, vertical gust speeds are less of a concern during takeoff and landing. Here, lateral speeds (crosswind) and changes in horizontal speed (gradients due to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3868/how-do-pilots-detect-and-respond-to-windshear-while-landing-and-taking-off/3870#3870&quot;&gt;microbursts&lt;/a&gt;) constitute the most important limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For crosswind limits, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.11&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR part 25.237&lt;/a&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) For land planes and amphibians, the following applies:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A 90-degree cross component of wind velocity, demonstrated to be&#xA;  safe for takeoff and landing, must be established for dry runways and&#xA;  must be at least 20 knots or 0.2 V$_{SR0}$, whichever is greater,&#xA;  except that it need not exceed 25 knots.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In the end, it is up to the pilot to decide whether to attempt to land in adverse conditions, to go around, or to fly to an alternate destination. &lt;a href=&quot;https://aviation.stackexchange.com/questions/14547/how-do-pilots-respond-to-wind-shear/14549#14549&quot;&gt;This answer&lt;/a&gt; gives some criteria which can be used by pilots to decide if they better go around. &lt;a href=&quot;https://aviation.stackexchange.com/questions/12619/why-do-airports-have-to-close-in-bad-weather&quot;&gt;Airports are closed rarely&lt;/a&gt; and only when severe weather approaches, such as thunderstorms and tornados, but then it is not due to a specific wind speed, but to the expected maximum speeds, which then will far exceed certification limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical gusts become more stressing with speed, because at the low lift coefficient of high speed flight a vertical gust will produce a relatively higher increase in lift coefficient than at low speed. In extreme cases, the wing will stall due to the gust, which will limit the additional structural loads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horizontal speed gradients, which are caused by downdrafts hitting the ground and spreading out, are most harmful at low speed. First the aircraft will encounter a headwind, which slows it down, and then rapidly cross into a tailwind which will cause airspeed to drop, in extreme cases below stall speed. &lt;a href=&quot;https://aviation.stackexchange.com/questions/21560/can-an-airliner-fly-out-of-a-downburst/21562#21562&quot;&gt;This can even crash a large airliner&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-11-29T22:35:36.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23259" PostTypeId="2" ParentId="23243" CreationDate="2015-11-29T17:18:53.990" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/maint/181623-1.html&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; gives a slightly dated (2002) overview of the engine upgrade options for a 182. There's no mention of auxiliary tanks being required, but it does note that for at least one option they're typically a good idea:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The IO-550 engine is a guzzler and if you don't have long-range tanks,&#xA;  you'll need them. Indeed, you'll probably want to consider Flint tip&#xA;  tanks for your Skylane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's possible that you've seen conversions where, for whatever reason, a cabin tank was added instead of - or even in addition to - tip tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking into an upgrade then if you aren't already a member you should consider joining the &lt;a href=&quot;http://cessna.org/&quot; rel=&quot;nofollow&quot;&gt;Cessna Pilots Association&lt;/a&gt; and search through their forums (members only) for whatever you can find. I found one thread on upgrading the C182 to an IO-550 but it didn't mention the fuel tanks at all, although I didn't search thoroughly.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-29T22:32:24.603" LastActivityDate="2015-11-29T22:32:24.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23260" PostTypeId="1" AcceptedAnswerId="23267" CreationDate="2015-11-29T18:46:51.827" Score="19" ViewCount="4078" Body="&lt;p&gt;&lt;em&gt;San Andreas&lt;/em&gt; is an awful movie, but given how helicopter-centric its plot is I'm wondering if they even got the autorotation landing correct?  In the middle of the movie the hero is cruising in (I think) a Bell 412 when the engines fail.  He tells his passenger they're going to autorotate, and he proceeds to do the following maneuver &lt;em&gt;three times&lt;/em&gt;: Precipitous pitch down, then after picking up a lot of speed, a flare.  (The final &quot;landing&quot; flare is attempted in a crowded parking lot where he tries a last-second evasive maneuver that destroys the helicopter.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that a proper autorotation always simply consists of pitching to a specified glide path and not changing pitch until the landing flare.  Do any conditions or rotary-wing vehicles call for a different autorotation maneuver?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastActivityDate="2016-02-27T11:16:59.967" Title="Is the autorotation in San Andreas movie realistic?" Tags="&lt;helicopter&gt;&lt;auto-rotation&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23261" PostTypeId="5" CreationDate="2015-11-29T19:08:47.547" Score="0" Body="" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-29T19:08:47.547" LastActivityDate="2015-11-29T19:08:47.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23262" PostTypeId="4" CreationDate="2015-11-29T19:08:47.547" Score="0" Body="Part 141 of the US Federal Air Regulations deals with pilot schools" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-29T19:08:47.547" LastActivityDate="2015-11-29T19:08:47.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23263" PostTypeId="2" ParentId="12619" CreationDate="2015-11-29T19:20:16.973" Score="-1" Body="&lt;p&gt;All of these questions answer from the point of view of the plane. Can it land, can it take off, can the pilots see, can they control the plane, etc. But there is another aspect not yet mentioned: ground staff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's incredibly common for long delays to be caused by thunderstorms because it's not safe for anyone to be outside during active lightning. This means the people who hold the sticks to show the planes where to park, the people who hook up the fuel trucks, the luggage handlers - dozens of people many of whom are handling dangerous equipment, and all of whom have to stay inside until the lightning stops. An airport may stop allowing landings and takeoffs &lt;strong&gt;even when the planes would have no trouble landing or taking off&lt;/strong&gt; because it's not safe for ground crew to be out there.&lt;/p&gt;&#xA;" OwnerUserId="3827" LastActivityDate="2015-11-29T19:20:16.973" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23264" PostTypeId="1" CreationDate="2015-11-29T19:47:55.910" Score="5" ViewCount="605" Body="&lt;p&gt;I'm curious if anybody could give any indications as to how many hours of test flight a &lt;strong&gt;factory new small general aviation aircraft*&lt;/strong&gt; goes through before customer acceptance and delivery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Not initial certification, but what is necessary for every new production airframe)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*&lt;em&gt;e.g. Cessna 172, Diamond DA-42 or Robinson R22&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="62" LastEditDate="2015-11-30T22:21:37.773" LastActivityDate="2015-12-01T19:48:11.997" Title="How many hours of test flight does a general aviation aircraft go through before delivery?" Tags="&lt;general-aviation&gt;&lt;easa-regulations&gt;&lt;flight-testing&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23265" PostTypeId="2" ParentId="23239" CreationDate="2015-11-29T20:08:55.607" Score="2" Body="&lt;p&gt;I guess one of the reasons for this wide-body use is because this is the primary aircraft for medium-haul routes in the Emirates Network. The 777 for Emirates is the workhorse of the Emirates airline and it has contributed to it's success. But in reality I do agree with you. Many Emirates routes that I have seen on YouTube do not have full aircraft which cannot be economically viable. But I guess this is why Emirates are so careful of assigning the A380 to a route. An example I can think of is Zurich which up till recently was operated by a 777. This is because the A380 is such a huge plane that it is only viable if the flight is packed. The 777 on the other hand is an aircraft that is used for a plethora of routes by Emirates. Reasons for this could be that it is the only widebody aircraft Emirates can use for this route. &lt;/p&gt;&#xA;" OwnerUserId="12440" LastActivityDate="2015-11-29T20:08:55.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23266" PostTypeId="2" ParentId="23212" CreationDate="2015-11-29T20:13:06.197" Score="1" Body="&lt;p&gt;For the UK NATS makes most of the charts which I frequently use for flight stimulation. I believe that for charts especially the Aerodrome charts are much better than the style of charts Jeppesen produce. The only downside is that the charts aren't compiled in the way that charts on Jeppesen are and must be compiled. But for outside the UK the best charts in my opinion are Jeppesen. &lt;/p&gt;&#xA;" OwnerUserId="12440" LastActivityDate="2015-11-29T20:13:06.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23267" PostTypeId="2" ParentId="23260" CreationDate="2015-11-29T20:24:05.137" Score="37" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=37YaGRQxIcY&quot; rel=&quot;nofollow&quot;&gt;Let's see how many things we can find wrong.&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;There's a bang, smoke starts coming from the exhaust.  Master caution comes on and his first response is to tap and check the 115v AC gauge!  The pilot takes his hand off the collective!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You hear the engine wind down and the rotor RPM drop.  He announces a gearbox failure.  So why did the engine wind down?  His passenger even asks if he switched the engine off.  If the gearbox had seized, the engine would have been destroyed or, the input shaft would shear and the engine RPM would increase leading to a very rapid overspeed.  There is no gearbox failure mode that results in the engine winding down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;He had a long think and a bit of a chat after the engine and RRPM wind down.  In a Bell 412, with the speed of that wind down, the blades would have stalled after 2 or 3 seconds if he hadn't dropped the collective.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;He announces that he is going to autorotate.  His passenger asks &quot;auto what?&quot;  He says we're going to crash.  The whole point of autorotation is that you don't crash.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With the RPM already low (let's forget that he would have stalled by now), his first action is to dive and you hear the RRPM increase.  In reality, they would go even lower.  If he wasn't already stalled (which of course he would have been) he would now.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;He was straight and level, with significant airspeed over level open ground.  At the first bang and sound of the engine winding down, he would have lowered the collective and flared to preserve RRPM. He would then look for a &lt;strong&gt;good&lt;/strong&gt; place to land, not a shopping centre car park, and fly towards it. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Each time he flares, he pitches forward again and the RRPM drop rapidly.  Flaring like that in auto would cause a large increase in RRPM, possibly overspeeding and lowering the nose to the level would cause a small drop in RRPM.  Diving again would reduce the RRPM.  So why would you flare to increase, then dive to decrease?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In short, the sequence is complete nonsense.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-02-27T11:16:59.967" LastActivityDate="2016-02-27T11:16:59.967" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="23268" PostTypeId="1" AcceptedAnswerId="23279" CreationDate="2015-11-29T20:41:34.083" Score="5" ViewCount="740" Body="&lt;p&gt;Is it possible to upgrade an old F-16A/B Block-15 to the F-16D/E Block-60/62 standard?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What modifications should be made, and how?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="1467" LastEditDate="2018-01-11T10:35:47.540" LastActivityDate="2018-01-11T10:35:47.540" Title="Is it possible to upgrade an old F-16 to the Block-60/62 standard?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;f-16&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23269" PostTypeId="1" AcceptedAnswerId="23277" CreationDate="2015-11-29T20:45:45.297" Score="2" ViewCount="506" Body="&lt;p&gt;Is it possible for an air force to operate a fighter aircraft indefinitely?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose a country has some Mig-21s or Mirage-IIIs. Is it possible for them to operate those aircraft indefinitely by continuously overhauling and upgrading them?&lt;/p&gt;&#xA;" OwnerDisplayName="user8792" LastEditorUserId="1467" LastEditDate="2017-12-14T08:48:08.263" LastActivityDate="2017-12-27T05:07:16.747" Title="Could a fighter aircraft be operated indefinitely?" Tags="&lt;military&gt;&lt;aircraft-maintenance&gt;&lt;fighter&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23270" PostTypeId="2" ParentId="23239" CreationDate="2015-11-29T21:47:18.993" Score="6" Body="&lt;p&gt;Eurostats provides information EU air passengers information, &lt;a href=&quot;http://ec.europa.eu/eurostat/help/new-eurostat-website?p_auth=82MXqaAJ&amp;amp;p_p_id=estatsearchportlet_WAR_estatsearchportlet&amp;amp;p_p_lifecycle=1&amp;amp;p_p_state=maximized&amp;amp;p_p_mode=view&amp;amp;_estatsearchportlet_WAR_estatsearchportlet_action=search&amp;amp;text=avia_par&quot; rel=&quot;nofollow noreferrer&quot;&gt;it details air passengers transport Each of EU countries and their main airport partner.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the above link, there is the passengers information between Dubai and Newcastle/Prague.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HTfVG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HTfVG.jpg&quot; alt=&quot;Newcastle&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/btNg6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/btNg6.jpg&quot; alt=&quot;Prague&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Departure meanes the flights from the cities to dubai, and arrival stands for the flights from dubai to the two cities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the load factor for Newcastle and Prague is around 70%, both are lower than &lt;a href=&quot;http://content.emirates.com/downloads/ek/pdfs/report/annual_report_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Emirates 79.6% average&lt;/a&gt;. Newcastle are serviced by 2-class B77W while Prague is serviced by 3-class b77w/a388.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Load factor of both cities are from 50% at low season to 80&amp;amp; at high season. Although load factor of Prague route is lower than Newcastle in 2015, please note that at that time &lt;a href=&quot;http://www.routesonline.com/news/29/breaking-news/249703/where-does-the-airbus-a380-fly-july-2015-network-update/?highlight=emirates%20prague&quot; rel=&quot;nofollow noreferrer&quot;&gt;Emirate ran this route by A388 instead of B77W&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: The nearest airport to Bologna which Emirates serves is Venice, not Milan,although the fastest way between 2 airports and Bologna are almost same.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-12-06T22:55:22.713" LastActivityDate="2015-12-06T22:55:22.713" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23271" PostTypeId="1" AcceptedAnswerId="23273" CreationDate="2015-11-29T22:03:40.317" Score="49" ViewCount="17362" Body="&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; Having read these great answers I feel a little ashamed for the fear I felt on this recent flight. However, judging by my reaction to the experience and the reaction of those around me on the flight I imagine I am not the only one who felt this way. As others have mentioned here I will agree that passengers are pretty bad at judging turbulence. For those who come to this Stack Exchange site with similar concerns, I hope that you read these answers from those knowledgeable in the field to assuage your concerns.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I was recently on a flight that flew in to central Texas coming from Denver. There was bad turbulence on the flight in the last 45 minutes -- the worst I have ever experienced -- and I was curious about what else was going on behind the scenes from the perspective of the pilot and crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know the airplane model. It has ~38 rows and 3 seats on each side of the aisle. I was in row 35. It was a standard commercial airplane that would fly across the United States.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We were first told that we were about to enter a turbulent area based on reports of other airliners in the region. We soon entered an area of lightning and dense clouds so thick that there was no visibility outside the windows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first drop came unexpectedly in what I can only describe as similar to a bad, bumpy landing on the freeway. The bags rattled pretty hard and loudly and I felt myself leave the seat. It was loud and jarring enough for most of the people in my area to scream out loud. Over the next 45 minutes, these drops happened continuously and randomly, up to 15 times. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between these big drops the plane felt like it was swaying from the left and right. There were also many tiny dips between the bigger dips. It was extremely tense for everyone on the plane and generally it felt very uneven below us so there was a constant anticipation of another drop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the landing gear went down, it was clear that we were ascending again. The pilot explained that there was a &quot;spacing&quot; issue on the ground so he was going to fly around and try to land again. The guy next to me said (jokingly?) that this meant the pilot was too scared to land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cabin crew looked pretty terrified, and they were chatting to each other throughout the whole ordeal. People were sobbing and weeping all around me and they would yell every time a drop happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, you have little information to go off of but I was curious, from what I have provided, about the following questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Many people on board were fairly traumatized by the experience. Was there any real danger from turbulence this bad? Is this something a pilot might encounter routinely that they would be equipped to handle or does this seem unusually bad?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What was happening behind the scenes? How does a pilot handle a situation like this? Was there other information about the turbulence that we were not being told?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Any other interesting, related information to give me insight into this experience would be appreciated.&lt;/p&gt;&#xA;" OwnerUserId="12467" LastEditorUserId="3504" LastEditDate="2015-12-02T15:43:33.590" LastActivityDate="2020-04-28T07:08:40.797" Title="How dangerous was the turbulence on this commercial flight?" Tags="&lt;safety&gt;&lt;turbulence&gt;" AnswerCount="6" CommentCount="20" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23272" PostTypeId="2" ParentId="22936" CreationDate="2015-11-29T22:08:34.083" Score="8" Body="&lt;p&gt;I've been in aircraft maintenance for over 15 years, and have worked about 10 different types of narrow and wide body aircraft, and have never once seen a maintenance manual direct me to test fly an aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a reason for this, though. Repairs done during &lt;strong&gt;routine&lt;/strong&gt; maintenance are designed by the manufacturer such that the repair itself makes the aircraft airworthy. That is usually part of the manufacturing and STC process, if I'm not mistaken. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, it's not entirely uncommon to have maintenance control or even maintenance management request a test flight. Usually this is done for troubleshooting or for repair verification. This is largely due to the fact that there are some problems that maintenance cannot duplicate on the ground. For example, I recently worked an airplane whose window heat failed at the top of descent about once every ten or eleven flights. I can simulate a lot of things on the ground, but what I can't simulate is the actual descent of the aircraft at about 37,000 feet! The problem had been ongoing for four or five months, but was sporadic enough not to trigger any alarms in the analysts office. It was only when you paid careful attention to the history of the problem that you realized it had major issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to regulatory requirements, and the way our GMM is written, if the aircraft had another occurrence on the next flight, it'd be &quot;dead&quot; at the next station it landed with no MEL relief. We made a repair, but it was really only a guess because there were no actual signs of wear/fatigue/damage and everything tested normally. Management requested a test flight, and asked the test crew to run it through the wringer, to see if it would fail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, there are certain systems that may require flight crew verification during flight prior to recertification. An auto land system that has had chronic failures may require the flight crew to perform an automatic landing before it can be recertified back to full CAT III landing status. But, this can often be done on a revenue flight, and is often not a dedicated flight meant to specifically test the system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also the rare case in which major structural repairs may require a test flight. I once saw a wide body aircraft that had a tail strike on landing. The damage was so severe, it literally twisted part of the empennage. In order to be repaired, our company required major involvement from the aircraft manufacturer. The manufacturer did provide a repair, but for obvious reasons, the engineers actually mandated several test flights afterward. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as far as I know, there is no regulatory requirement which says that a certain repair requires a test flight. From what I've seen, and perhaps this may sound awful, you kind of &quot;know&quot; when an airplane needs a test flight. &lt;/p&gt;&#xA;" OwnerUserId="12452" LastActivityDate="2015-11-29T22:08:34.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23273" PostTypeId="2" ParentId="23271" CreationDate="2015-11-29T22:25:29.693" Score="70" Body="&lt;p&gt;Very little to go on (non-pilots are lousy at classifying turbulence) but my best guess is that you experienced &lt;a href=&quot;https://aviation.stackexchange.com/questions/12117/do-we-have-a-unit-to-measure-turbulence&quot;&gt;moderate turbulence&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it was severe, your description would have been something more like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I couldn't focus my eyes to see. Someone who wasn't belted down was&#xA;  flung violently against the ceiling, then slammed to the floor. The&#xA;  captain was very assertive, telling the FAs to be seated immediately and&#xA;  that all passengers must strap in. The flight attendants wedged the&#xA;  service carts into the gaps between the seats and asked some&#xA;  passengers to hold them down, before sitting down and securing&#xA;  themselves in with their full 4 point harness. During the worst of it, there was no way anyone would have been able to stand, even if you were holding onto the seats or walls. Some overhead bins&#xA;  popped open strewing their&#xA;  contents about the cabin. There was coffee, cups, plastic glasses,&#xA;  books, etc. flying around EVERYWHERE. Several&#xA;  people had to be taken off the plane by stretcher.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pilots are not &quot;scared to land&quot;. If it's not safe, they will divert. If the approach is wrong, they will &quot;go around&quot; (both perfectly normal) and spacing issues are the most likely reason. Why would the captain lie? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://askthepilot.com/questionanswers/turbulence&quot; rel=&quot;noreferrer&quot;&gt;Ask a pilot.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reaction of passengers is not a good indicator of the level of turbulence but the bottom line is, aircraft are designed to cope with the worst turbulence, and then some. You were perfectly safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have to take issue with your use of &quot;air hostesses&quot;, I believe you mean &quot;cabin crew&quot; or &quot;flight attendants&quot;.  We stopped calling them that when we realised that they are actually professionals with a vital safety role as their primary function and are of both genders. &lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-09-10T06:48:14.010" CommentCount="23" ContentLicense="CC BY-SA 3.0" />
  <row Id="23274" PostTypeId="2" ParentId="23271" CreationDate="2015-11-29T22:29:32.273" Score="12" Body="&lt;p&gt;Turbulence can be caused by a variety of different weather patterns.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one you describe in TX as &quot;an area of dense clouds and lightning so thick that there was no visibility outside the windows&quot; is probably a thunderstorm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the cockpit, pilots have a weather radar system that tells them instantaneously where the densest area of precipitation is, such as the magenta area at the far right of the 40nm arc. Aircraft equipped with radar can easily fly around the worst parts of the storm, but that doesn't mean they miss it all together. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your pilot probably had to fly through part of the storm to get to the destination. The go-around could have been for 'spacing,' but it could have been a normal missed approach as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GkVVf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GkVVf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-04-28T07:08:40.797" LastActivityDate="2020-04-28T07:08:40.797" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="23275" PostTypeId="2" ParentId="3645" CreationDate="2015-11-29T22:59:52.483" Score="4" Body="&lt;p&gt;Gliders make sustained flight on the backside of the lift curve all the time while thermalling at 40-50 knots and 50 degrees of bank. You spend a lot of time adjusting the elevator to keep the plane from stalling, a lot of time adjusting the ailerons to keep the bank angle, and a lot of time trying to stay coordinated (or in a slight slip) with your feet.  The bigger the wingspan, the more work it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big difference in a glider is that you're usually going up, not down when this happens :)  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2015-11-29T23:10:43.373" LastActivityDate="2015-11-29T23:10:43.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23276" PostTypeId="2" ParentId="23264" CreationDate="2015-11-29T23:38:58.503" Score="1" Body="&lt;p&gt;There is no regulatory requirement. It must be legally airworthy before any flight including its first one. Most flying done before delivery is to reposition aircraft to dealership or mod center.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2015-11-29T23:38:58.503" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23277" PostTypeId="2" ParentId="23269" CreationDate="2015-11-29T23:46:13.353" Score="12" Body="&lt;p&gt;Yes and no. In Cambridgeshire we still have some Spitfires and other Second World War aircraft which are still operated more than 60 years after being built. The Shuttleworth Collection even flies some First World War and pre-war aircraft. It's demonstrably possible to keep operating a military aircraft for at least a century after it's built.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that's not useful if the aircraft has no military value. None of the examples I've mentioned are still operated &lt;em&gt;as military aircraft&lt;/em&gt;: they're in civilian hands, performing for displays, mostly for their historic value (though many ex-military aircraft in civil use are performing other functions, such as air transport or crop spraying).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft get retired for two reasons. The most obvious is that they're superseded by newer types, newer designs with better technologies and materials. The first air force that tried to field one of these Spitfires in combat against modern jet fighters would quickly realise it had no military value whatsoever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second reason is that they get increasingly expensive to maintain. Military aircraft especially can be very fussy about fuels and parts. Maintenance might require special fabrication of small numbers of parts or tools, which gets more expensive when the rest of the industry has moved on. (For example, the Tiger Moths I fly have one particular part that's impossible to obtain, because the alloy it's made of isn't produced any more.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this reason, although there are still surviving, operating aircraft from the earliest days of military aviation, it wouldn't be feasible or useful to continue operating them as combat aircraft.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-11-29T23:46:13.353" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23278" PostTypeId="2" ParentId="23271" CreationDate="2015-11-30T00:06:15.550" Score="50" Body="&lt;p&gt;I agree with @Simon that, given your description, you were in moderate turbulence, and as such you were not at risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You mentioned that the flight attendants looked terrified, which implies that you were able to see their faces, which might mean they were up and about? If so, you were not in severe turbulence. In severe turbulence the flight attendants are going to be strapped down. My guess would be that what you saw on the the flight attendants' faces was irritation rather than terror, unless they were newbies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Simon mentioned, passengers are poor reporters when it comes to turbulence. I was in the back of a 727 well aft of the wing over Texas many years ago. They stopped the beverage service when a flight attendant got dumped onto a passenger's lap. I already had my carton of milk (I'm a milkaholic). I was trying to drink it between bumps without much success, and I found my efforts laughable and started laughing. The passenger next to me asked how I could laugh at a time like this when we were obviously in great danger. I said something like, ah, what danger? to which he replied that I should look at the wing tips, that they were moving up and down. Whether my explanation that they were supposed to do that and that we were in no danger really consoled him or not, I do not know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's an oversimplification, but the wing is designed to stall before it will overstress the aircraft, regardless of the turbulence. People have been occasionally hurt in severe turbulence, though, by flying about because they didn't fasten their seat belt, or by overhead bag compartments opening and bags flying. It's very rare though, and preventable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large aircraft typically have a recommended turbulence penetration speed to ensure margins for both the high-speed buffet and stall speeds. The 747-100/200 aircraft also had a TURB mode for the autopilot for use in moderate to severe turbulence, although I always found I could do a better job hand-flying than those old autopilots could insofar as handling turbulence. I would guess that current autopilots can do a better job than hand-flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My personal way of judging whether we were in truly severe turbulence was that if I was having trouble reading the instruments because my eyeballs were jiggling too much, that was severe turbulence. Also, if you're in it long enough, when the flight is over, the area around your hips may be a little sore for having been forced against your seat belt so hard and so often.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="753" LastEditDate="2015-11-30T12:29:25.843" LastActivityDate="2015-11-30T12:29:25.843" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23279" PostTypeId="2" ParentId="23268" CreationDate="2015-11-30T01:12:38.063" Score="8" Body="&lt;p&gt;F-16D/E Block-60 is an evolutionary upgrade to the F-16A/B Block-15 with the following differences:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine: General Electric F110-GE-132 in place of Pratt &amp;amp; Whitney F100-PW-200 turbofan.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Avionics: This is where the majority of upgrades have been carried out. Block 60 has the AN/APG-80 'Agile Beam' AESA radar, AN/ASQ-28 IFTS (Internal FLIR and Targeting System) replacing the earlier external pods, ALQ-165 electronic countermeasures system, improved pilot displays, improved mission computer and ability to fire more weapons like AIM-132 and AGM-154.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The main structural modification is the addition of conformal fuel tanks in the wings, with slight change in dimensions and increase in MTO weight- 46,000lb vs 37,500 lb&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0d12a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0d12a.jpg&quot; alt=&quot;F16 Block 15&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 Block 20, Image from f-16.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VIpmE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VIpmE.jpg&quot; alt=&quot;F16 Block 60&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 Block 60, Image from f-16.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though it is &lt;em&gt;possible&lt;/em&gt; to upgrade block 15 to block 60 (albeit with some heavy modifications), the question is why anyone one would do that. Even the youngest Block 15 aircraft is nearly 20 years old (the last aircraft rolled off the assembly line in 1996) and LM has shut down the F-16 production line. The upgrade will be costly (you're changing some of the costliest items in the aircraft- avionics and engines) and will not be cost-effective in an aircraft past half its service life. Also, as far as I know LM doesn't offer any upgrades from Block 15 to 60, indicating consumer indifference.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-11-30T01:12:38.063" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23280" PostTypeId="1" CreationDate="2015-11-30T04:09:08.263" Score="4" ViewCount="534" Body="&lt;p&gt;I just saw &lt;a href=&quot;https://youtu.be/0qrGOhgLQY8?t=57s&quot; rel=&quot;nofollow noreferrer&quot;&gt;a Delta commercial&lt;/a&gt; with a plane taking off from a runway with a 16R designation (thus, the plane in the commercial was departing from 34L). Does anyone know where this airport is? Climbing out, there appears to be a large body of water ahead, if that helps!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KnaEY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KnaEY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had always heard that &lt;a href=&quot;https://www.airnav.com/airport/KVNY&quot; rel=&quot;nofollow noreferrer&quot;&gt;Van Nuys (KVNY)&lt;/a&gt; was the only airport with a 16R/16L runway designation, but the airport in the video isn't Van Nuys.&lt;/p&gt;&#xA;" OwnerUserId="12472" LastEditorUserId="3504" LastEditDate="2015-11-30T18:01:37.243" LastActivityDate="2015-12-04T06:05:43.443" Title="Which airport is featured in this Delta commercial?" Tags="&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23281" PostTypeId="2" ParentId="23280" CreationDate="2015-11-30T05:01:02.280" Score="0" Body="&lt;p&gt;You can find the full list of &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/airportdata_5010/menu/#datadownloads&quot; rel=&quot;nofollow&quot;&gt;runway data for the US here (as provided by the FAA)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They list (confirmed on google maps to see whats actually painted on the tarmac)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;DEN (Denver)&lt;/li&gt;&#xA;&lt;li&gt;SEA (Seattle-Tacome)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There may be others as well you can check the list for a more complete overview. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-30T05:01:02.280" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23282" PostTypeId="2" ParentId="23280" CreationDate="2015-11-30T05:05:48.497" Score="10" Body="&lt;p&gt;It's &lt;strong&gt;&lt;a href=&quot;http://www.airnav.com/airport/KPAE&quot; rel=&quot;nofollow noreferrer&quot;&gt;Paine Field (KPAE)&lt;/a&gt; in Seattle&lt;/strong&gt;. It has both 16L and 16R and has water (the Puget Sound) directly ahead if you're taking off from the 34s. 34L is also the only runway there large enough for most jet traffic, so that's what a Delta jet would be using if it were there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that this commercial is about flight testing and Paine Field just so happens to be the home of an aircraft production facility for some little company named 'Boeing.' You can see their &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Everett_Factory&quot; rel=&quot;nofollow noreferrer&quot;&gt;Everett Production Facility&lt;/a&gt; on the North side of the airport in the Google Earth view and the aerial photo below. Interesting fact: that facility, originally built in 1967 to produce the Boeing 747, &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_largest_buildings_in_the_world#Largest_usable_space&quot; rel=&quot;nofollow noreferrer&quot;&gt;remains the largest building in the world by volume&lt;/a&gt; even to today. It's 79% larger than the next largest building and a full 3.63 times the size of NASA's &lt;a href=&quot;https://en.wikipedia.org/wiki/Vehicle_Assembly_Building&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vehicle Assembly Building&lt;/a&gt;, the previous largest building in the world by volume, where NASA performed final integration of the Saturn V and Space Shuttle stacks and where it will do so for the SLS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the Google Earth view, and it looks like the two islands on the left in the commercial are Hat Island and Camano Island:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2wlQQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2wlQQ.png&quot; alt=&quot;Google Earth view of Paine Field&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wLPfd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wLPfd.jpg&quot; alt=&quot;Sectional chart showing KPAE and Puget Sound&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Sectional Chart Showing KPAE&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/67fdh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/67fdh.jpg&quot; alt=&quot;Paine Field - Aerial View&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Aerial View of Paine Field - Source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Aerial_Paine_Field_August_2009.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Honestly, the claim of there only being 1 airport with any given runway number seems rather suspicious, since there are only 18 possibilities. Granted, the requirement of having parallel runways makes it a little less unlikely, but still many (if not most) large airports have parallel runways.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2015-12-04T06:05:43.443" LastActivityDate="2015-12-04T06:05:43.443" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23283" PostTypeId="2" ParentId="23239" CreationDate="2015-11-30T06:59:08.000" Score="7" Body="&lt;p&gt;I may try and answer for Bologna which could be a similar case as for other supposedly non busy airports. (I am from Bologna myself!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the reason is that even though the airport is not on the top 30, Bologna itself is one of the busiest economic hubs in Italy. For example from here we have factories like Ferrari, Maserati, Lamborghini and Ducati which are all in the radius of 30 km from the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if it does not make sense passenger-wise I think it does commercially.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also another theory which I have heard from FastJet management (Low cost regional carrier in Tanzania) which serves neighbouring countries. Sometimes you do not have to serve where there is business. The simple fact that you are opening a new route will automatically create business. As an airline YOU are creating the business for many other sectors. This is very true for example for Harare where now, with FastJet there are a lot of people flying into Dar es Salaam to pick up used cars shipped from Japan. This was not happening before but it is now a reality and their flights are fully booked for months from Harare to Dar es Salaam. On the other way (DSM-Harare) there are not many passengers but the pilots are telling me that the plane is fully laden with cargo! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So sometimes it seems that a route is not profitable but probably because no one is doing it. The moment you open it up, BANG! like magic new businesses start to flourish!&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-11-30T06:59:08.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23284" PostTypeId="1" AcceptedAnswerId="23311" CreationDate="2015-11-30T07:30:03.783" Score="6" ViewCount="1474" Body="&lt;p&gt;&lt;strong&gt;Scenario&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lets imagine a 50kts wind from east.&#xA;Now lets imagine an aircraft flying at 200kts (True Air Speed) east that make a 1.15G turn -90º to north. Maintaining in all moments the given constant speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, lets imagine the same flight but with 200kts constant ground speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LR3p0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LR3p0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first case, the speed is 200kts TAS= 150kts GS, and after the turn TAS=GS=200kts&#xA;In the second case, the speed is 200kts GS = 250kts TAS, and after the turn, TAS=GS=200kts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any mistake until now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The question:&lt;/strong&gt;&#xA;The question is how that influence the turning circle? In which of the two cases the turning circle is flatten/stretched and in which is circular if any? What is the approximate shape of them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Further explanation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering my very weak understanding, the turning circle G depend on absolute speed (~ Ground speed), and thus, turning with a constant ground speed imply a circular turning. Which is independent of the wind. Of course, the pilot would have to accelerate/decelerate to maintain this speed.&#xA;With TAS, the real speed is variable, so in our case, I expect to see a turning circle which is horizontally flatten.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, using a planning system, the result I observe is the reverse: the circle is constant (independent of wind, circular) on TAS and variable (dependent on wind, shape is not drawn) in GS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edited: TAS=GS=200kts: I just realized that it is not really true, cause the aircraft need to head slightly east to compensate the wind, so probably the TAS will be ~206 and GS 200. Even if that do not make a big difference for the question.&lt;/p&gt;&#xA;" OwnerUserId="12474" LastEditorUserId="19" LastEditDate="2016-08-01T08:08:18.743" LastActivityDate="2016-08-01T08:08:18.743" Title="Constant TAS versus constant GS: What is the influence on turning circle?" Tags="&lt;aircraft-performance&gt;&lt;weather&gt;&lt;flight-planning&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23285" PostTypeId="2" ParentId="23239" CreationDate="2015-11-30T08:30:12.137" Score="6" Body="&lt;p&gt;Don't forget that aircraft size and link capacity are only loosely related, because it also depends on how many flights there are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example in case of Prague, I counted 6 departures to Frakfurt and 7 to Amsterdam a day, while only 2 to Dubai (the Emirates B77W and one SmartWings B738). So while the flights to Frankfurt and Amsterdam are all smaller planes (A319, A320, A321, to AMS some are even just E190), the capacity to both those destination is about double that to Dubai.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the closer hubs, it makes more sense to fly smaller planes more often, because it can be more easily scaled (e.g. swapping A320 for A321; they don't even have to change the crew for that) and because it allows shorter transfer times, which the passengers obviously prefer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However Dubai is much further and the small aircraft are less practical for that distance and for long trips, the stopover is smaller fraction of the travel time, so the passengers are more willing to accept it. So Emirates flies just once per day and uses large aircraft.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-11-30T08:30:12.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23286" PostTypeId="2" ParentId="23284" CreationDate="2015-11-30T11:10:32.537" Score="2" Body="&lt;p&gt;The radius of the turning circle depends on the True Air Speed, not the Ground Speed. TAS is the true measure of aircraft performance and is used in  every situation when actual performance needs to be measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the forces on an aircraft in a coordinated turn with a banking angle of $\phi$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/waaFJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/waaFJ.png&quot; alt=&quot;Coordinated turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from code7700.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the load factor n on the aircraft is simply the ratio of the lift to the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$n  =  \frac{L}{W} = \frac{1}{cos\phi}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The centripetal force acting on the aircraft can be given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F = L sin\phi$, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;which is equal to,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F = m . \frac{v^{2}}{R}$, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $v$ is the TAS and $R$ is the radius of turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Solving, we get,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R = \frac{v^{2}}{g . tan\phi}$, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;or in terms of load factor,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R = \frac{v^{2}}{g . \sqrt{n^{2} - 1}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in all these cases, the velocity $v$ is the TAS, not the ground speed. So, for a 1.15g (or n equals any other value) turn, greater the speed, bigger the turn radius, &lt;em&gt;at a constant bank angle&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I'll just list out the various speeds used for qualifying aircraft performance&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Indicated Air Speed&lt;/em&gt; is the the speed of an aircraft as shown on its pitot static airspeed indicator, calibrated to reflect standard atmosphere adiabatic compressible flow at sea level. Simply put, it is what the airspeed indicator shows.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Calibrated Airspeed&lt;/em&gt; is the indicated airspeed corrected for various errors (like instrument and position errors)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Equivalent Air speed&lt;/em&gt; is the airspeed at sea level in the ISA at which&#xA;the dynamic pressure is the same as the dynamic pressure at the true airspeed (TAS) and altitude at which the aircraft is flying.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;True Air Speed&lt;/em&gt; is the speed of the aircraft relative to the atmosphere. This is the speed used for measuring the aircraft performance. The TAS, along with the heading, gives the aircraft velocity relative to the atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Ground Speed&lt;/em&gt; is the vector sum of aircraft velocity and wind velocity (at the flight altitude). This gives the speed of the aircraft relative to the ground. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nSbVr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nSbVr.png&quot; alt=&quot;Air Speeds&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from stackexchange.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ground speed is rarely used in measurement of aircraft performance directly. The performance measurements are made with reference to the atmosphere as the frame of reference. This means that the True air speed, which gives the velocity with respect to the atmosphere is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-------------------------------------------------------------------------------For an observer on ground, the turn will be a circle if the TAS is equal to the ground speed i.e. if there is no wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a head wind, the turn will be squeezed i.e. the turning circle will be egg shaped, with the squished side in the direction of motion. For tail wind, the squished side will be in the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The case where headwind is equal to TAS is the limiting case- basically, the aircraft will appear to the ground observer to turn along a line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It will be like some one on shore seeing a swimmer turning in a water body where the water currents vary.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-01T00:25:09.157" LastActivityDate="2015-12-01T00:25:09.157" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23287" PostTypeId="1" AcceptedAnswerId="23289" CreationDate="2015-11-30T11:21:44.513" Score="2" ViewCount="1825" Body="&lt;p&gt;I came across this helicopter and am wondering what the oblong things on either side of the helicopter are, parallel to the front-back axis, offset from the main body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bWfix.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bWfix.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lY4YI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lY4YI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="657" LastEditorUserId="19" LastEditDate="2016-07-11T14:24:09.417" LastActivityDate="2016-07-11T14:24:09.417" Title="Can you help me to identify this helicopter?" Tags="&lt;helicopter&gt;&lt;aircraft-identification&gt;&lt;rotorcraft&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23289" PostTypeId="2" ParentId="23287" CreationDate="2015-11-30T11:40:29.763" Score="6" Body="&lt;p&gt;The helicopter is a Sikorsky CH-53 (probably an 'E' model).&#xA;According to &lt;a href=&quot;http://www.sikorskyarchives.com/S-65H-53D%20SEA%20STALLION.php&quot; rel=&quot;noreferrer&quot;&gt;this site&lt;/a&gt;, the two sponsons holding the fuel tanks are also the place where the landing gear retract.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Probably not an 'E' model as the 'E' model has a seven-blade rotor, while the one in this picture doesn't. &#xA;I'd say this is a 'D' model or an MH-53 'J' model.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastEditorUserId="9656" LastEditDate="2015-11-30T11:51:54.733" LastActivityDate="2015-11-30T11:51:54.733" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23291" PostTypeId="2" ParentId="23287" CreationDate="2015-11-30T12:18:55.010" Score="13" Body="&lt;p&gt;The helicopter is a S-65C-3 Yas'ur (Albatross). It is a CH-53D version similar to USAF HH-53C Pave Low. Here is a photo of the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7owA0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7owA0.jpg&quot; alt=&quot;CH 53&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The identification is based on the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Six bladed main rotor &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The sponsons which hold the fuel&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The only variant of CH-53D with in-flight refueling probe in service is the Israeli version. All others (HH-53 and MH-53) have been retired. CH-53E has refueling probe, but it has 7 blades.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Israel ordered 36 of these,of which around 23 are still in service.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-30T13:54:55.223" LastActivityDate="2015-11-30T13:54:55.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23293" PostTypeId="1" AcceptedAnswerId="23295" CreationDate="2015-11-30T13:30:29.557" Score="7" ViewCount="5721" Body="&lt;p&gt;I saw an image of an F-15 landing. What is that flap-like thing in the top of the plane in this picture? I couldn't find it on any other pictures or drawings of this aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BNKWh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BNKWh.jpg&quot; alt=&quot;f15 flap thing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11451" LastEditorUserId="1467" LastEditDate="2017-12-14T08:46:25.883" LastActivityDate="2017-12-14T08:46:25.883" Title="What is this &quot;flap-like&quot; thing on the back of the F-15?" Tags="&lt;landing&gt;&lt;aircraft-systems&gt;&lt;jet&gt;&lt;fighter&gt;&lt;f-15&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23294" PostTypeId="2" ParentId="23293" CreationDate="2015-11-30T13:35:41.130" Score="5" Body="&lt;p&gt;It's an air brake, also called a speedbrake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_brake_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Air_brake_(aeronautics)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another view of an F-15 landing with the speed brake open:&lt;br&gt;&#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/F-15_Eagle_landing_with_the_speed_brake_up.jpg/1200px-F-15_Eagle_landing_with_the_speed_brake_up.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/F-15_Eagle_landing_with_the_speed_brake_up.jpg/1200px-F-15_Eagle_landing_with_the_speed_brake_up.jpg&quot; alt=&quot;Eagle landing&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: Wikipedia, click to embiggen&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2520" LastEditorUserId="5517" LastEditDate="2015-11-30T17:59:47.050" LastActivityDate="2015-11-30T17:59:47.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23295" PostTypeId="2" ParentId="23293" CreationDate="2015-11-30T13:36:03.723" Score="6" Body="&lt;p&gt;It is a speed brake (air brake). Here is a closeup of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EVNwo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EVNwo.jpg&quot; alt=&quot;Speed brake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from aero-cafe.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is usually used reducing speed landing (approach). It is also used for other functions- to slow down quickly at high speeds and to prevent too much speed buildup in a dive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image shows it being used during approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ktseb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ktseb.jpg&quot; alt=&quot;F-15 speed brake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-15A_21st_TFW_landing_with_extended_speed_brake_1984.JPEG#/media/File:F-15A_21st_TFW_landing_with_extended_speed_brake_1984.JPEG&quot; rel=&quot;noreferrer&quot;&gt;F-15A 21st TFW landing with extended speed brake 1984&lt;/a&gt;&quot; by SSgt. K. Vail, USAF - U.S. DefenseImagery photo VIRIN: DF-ST-85-11671. Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar airbrakes are also found in other aircraft, notably the Su 27 and its derivatives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EYOy6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EYOy6.jpg&quot; alt=&quot;Su 27 airbrakes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from aerospaceweb.org&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-11-30T13:44:10.930" LastActivityDate="2015-11-30T13:44:10.930" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23296" PostTypeId="1" CreationDate="2015-11-30T13:45:19.940" Score="4" ViewCount="3453" Body="&lt;p&gt;I just wanted to clear up questions I have about flying within the 30 mile veil of Class B. My understanding is that the Class B is the inverted wedding cake, having tiers as the airspace moves towards the center. If I remain outside of the published altitudes, yet within the 30 mile veil, am I required to have a Mode C transponder? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the requirements if I have no electrical system on my plane?&lt;/p&gt;&#xA;" OwnerUserId="12482" LastEditorUserId="62" LastEditDate="2015-11-30T15:33:22.990" LastActivityDate="2015-11-30T15:46:47.917" Title="When is a transponder required below class B airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;transponder&gt;&lt;class-b-airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23297" PostTypeId="1" AcceptedAnswerId="23638" CreationDate="2015-11-30T14:24:23.367" Score="8" ViewCount="389" Body="&lt;p&gt;I'm looking for a tool to allow me to see what is within X nms or X hrs of my base airport. Is there such a thing?  I remember a small airport I flew to once had a large map with a string attached to a pin located at the airports location on the map.  There were concentric rings from the location stating 100/200/300....nm. I'm basically looking for something like that such that I could explore and look for locations that are off my normal radar of places I would typically visit.  I typically use landings.com for baseline flight planning but you need an origin and destination. It doesn't look like it allows what I'm asking for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd even be happy if there was a hack for google maps etc. to do what I'm asking. &lt;/p&gt;&#xA;" OwnerUserId="12483" LastEditorUserId="52" LastEditDate="2015-11-30T15:13:44.460" LastActivityDate="2015-12-14T01:37:14.000" Title="Is there a tool to plot locations within X nm of a position?" Tags="&lt;flight-planning&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23298" PostTypeId="2" ParentId="23296" CreationDate="2015-11-30T14:29:14.560" Score="0" Body="&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Equipment/Transponder-Requirements&quot; rel=&quot;nofollow&quot;&gt;From AOPA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For flying into a Mode C veil without an operable transponder, the pilot needs to telephone the appropriate radar facility for the Class B airspace and ask for permission to make the flight. Upon agreeing to conditions (including direction of flight and altitude), the pilot will be given a code number that he will mention to the controller upon initial radio contact. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you will need a radio but that does not mean you need an electrical system, a hand held should suffice. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-11-30T14:29:14.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23299" PostTypeId="2" ParentId="23296" CreationDate="2015-11-30T14:31:55.933" Score="2" Body="&lt;p&gt;Short answer: mode C is required unless the aircraft was originally certificated without an electrical system; but ATC can always authorize you to operate within the veil anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question isn't exactly about class B airspace itself, it's about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mode_C_veil&quot; rel=&quot;nofollow&quot;&gt;mode C veil&lt;/a&gt;; those are separate things although they do go together. (Note that from 1 Jan 2020, you'll require ADS-B out to operate within the veil so the name will be a bit outdated).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow&quot;&gt;AIM section 3-2-3&lt;/a&gt; has a good explanation of the transponder requirements but the regulations are more precise and complete. They're in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1215&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.215(b)(2)&lt;/a&gt; (and see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1225&quot; rel=&quot;nofollow&quot;&gt;91.225(d)(2)&lt;/a&gt; for the ADS-B ones) and they apply within the veil, not within class B:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;All aircraft&lt;/em&gt;. In all airspace within 30 nautical miles of an airport&#xA;  listed in appendix D, section 1 of this part from the surface upward&#xA;  to 10,000 feet MSL;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means that the shape of the class B airspace has nothing to do with the shape of the veil, which is always a cylinder 30nm across and 10,000ft high. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for operating without an electrical system, that's covered in the same section. If the aircraft has no electrical system &lt;em&gt;by design&lt;/em&gt; then you can operate within the veil but clear of class B:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;any aircraft which was not originally certificated with an&#xA;  engine-driven electrical system or which has not subsequently been&#xA;  certified with such a system installed, balloon or glider may conduct&#xA;  operations in the airspace within 30 nautical miles of an airport&#xA;  listed in appendix D, section 1 of this part provided such operations&#xA;  are conducted—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Outside any Class A, Class B, or Class C airspace area; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Below the altitude of the ceiling of a Class B or Class C&#xA;  airspace area designated for an airport or 10,000 feet MSL, whichever&#xA;  is lower; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the aircraft has an electrical system but it isn't working (i.e. you're taking the aircraft for maintenance) then you can request authorization from ATC to operate within the veil:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) &lt;em&gt;ATC authorized deviations&lt;/em&gt;. Requests for ATC authorized deviations&#xA;  must be made to the ATC facility having jurisdiction over the&#xA;  concerned airspace within the time periods specified as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) For operation of an aircraft with an inoperative transponder to&#xA;  the airport of ultimate destination, including any intermediate stops,&#xA;  or to proceed to a place where suitable repairs can be made or both,&#xA;  the request may be made at any time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can also request ATC authorization if you don't have a transponder, or if it doesn't have mode C. But if you don't have a transponder, you need to request authorization at least one hour in advance, you can't request it &quot;at any time&quot; as you can in other cases (see 91.215(d)(3)).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-11-30T15:46:47.917" LastActivityDate="2015-11-30T15:46:47.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23300" PostTypeId="2" ParentId="16180" CreationDate="2015-11-30T17:29:05.817" Score="2" Body="&lt;p&gt;Adding to &lt;a href=&quot;https://aviation.stackexchange.com/a/16190/12485&quot;&gt;Peter's answer&lt;/a&gt;, one of the flow disturbances that has to be avoided is flow separation in the inlet cowl. More specifically, the flow separation at the beginning of the lower inlet lip.&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-11-30T17:29:05.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23301" PostTypeId="2" ParentId="23284" CreationDate="2015-11-30T17:36:57.957" Score="1" Body="&lt;p&gt;&lt;strong&gt;Ignoring the wind:&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your first case has a constant TAS, so you should expect a constant radius (i.e., circular) path.  (Speed isn't changing, bank angle or 'g' isn't changing, so constant radius)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your second case requires the plane to reduce its TAS from 250kts to 200kts without changing the bank angle.  That will affect the no-wind path to make a &quot;decreasing radius turn&quot;.   (@Aeroalias's answer shows the relationship between radius and velocity). For a given bank angle, a lower air speed will result in a smaller turn radius.  Imagine a 1.15g turn in the SR-71 vs the same 1.15g turn in a Piper Cub.  Since you're slowing down during the turn, your no-wind path will look more like the letter &quot;J&quot; than a quarter-circle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Not ignoring the wind:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Up until now I've talked about the no-wind situation, because the airplane doesn't really know or care about the ground.  It's just swimming through a large mass of air.  &quot;Wind&quot; is what we call that air mass when is moving relative to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the first case, the wind will &quot;squish&quot; the ground track of the latter 1/2 of your turn to make it somewhat &quot;J&quot; shaped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the 2nd case, the wind will &quot;squish&quot; the ground track of the latter 1/2 of your J-shaped turn to make it appear to be sharper (less circular).&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="52" LastEditDate="2015-11-30T19:31:07.077" LastActivityDate="2015-11-30T19:31:07.077" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23302" PostTypeId="2" ParentId="23297" CreationDate="2015-11-30T18:07:46.897" Score="1" Body="&lt;p&gt;Google Earth probably has tools to do what you are looking for.  There's a lot of flexibility in that program to create overlays.  It can sometime take some knowledge of programming to do the more complex stuff but it is a very powerful program.  &lt;/p&gt;&#xA;" OwnerUserId="7752" LastActivityDate="2015-11-30T18:07:46.897" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23303" PostTypeId="1" AcceptedAnswerId="23304" CreationDate="2015-11-30T20:04:37.743" Score="2" ViewCount="295" Body="&lt;p&gt;I'm wondering if GA piston engines have a tendency to stall like some old carburetor car engines if the throttle is increased too quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would happen or what could be done if this scenario occurs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it happened in cars sometimes you could not restart until the residual fuel was burnt by cranking the engine for some time. Does this apply also to aviation engines?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question arises from the fact that the design of the engines are quite old from my understanding.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2015-12-01T07:05:42.180" LastActivityDate="2015-12-01T20:58:46.873" Title="Do GA gasoline engines have a tendency to cough, and splutter?" Tags="&lt;general-aviation&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23304" PostTypeId="2" ParentId="23303" CreationDate="2015-11-30T20:12:13.417" Score="8" Body="&lt;p&gt;The short answer to your question is: Yes &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its generally advised to avoid making abrupt power changes to aircraft engines (piston and &lt;a href=&quot;https://en.wikipedia.org/wiki/Compressor_stall&quot; rel=&quot;nofollow&quot;&gt;jet for that matter&lt;/a&gt;) to avoid surge and potential starvation issues. You are usually taught to apply and reduce power smoothly when learning to fly. Aircraft piston engines are not really all that different than older air cooled car engines (think VW and early Porsche (there was an aircraft certified &lt;a href=&quot;https://en.wikipedia.org/wiki/Porsche_PFM_3200&quot; rel=&quot;nofollow&quot;&gt;Porsche motor actually&lt;/a&gt;)). As such they can (and sometimes do) suffer from the same pitfalls.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference you may see in aircraft engines is that they tend to be a bit better set up and less tinkered with than car engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like any gas engine aircraft engines have been known to, on occasion suffer from &lt;a href=&quot;https://en.wikipedia.org/wiki/Vapor_lock&quot; rel=&quot;nofollow&quot;&gt;vapor lock&lt;/a&gt; and fuel pump failure as well. The most &lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/skills/carbicing.html&quot; rel=&quot;nofollow&quot;&gt;dangerous and potentially serious issues in aircraft carburetors is ice build&lt;/a&gt; up due to high moisture and low temperatures at higher altitudes. Airplanes have carb heating systems that are manually controlled from the cockpit to solve this problem. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What would happen or what could be done if this scenario occurs?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally speaking this is a rare occurrence and often happens on the ground. Keep in mind that plane throttles are (during a routine flight) adjusted far less than a car throttle. In a car you may be going through a street with lots of stop lights causing you to go from idle to cruise/launch power frequently. In an airplane this really only happens once on take off and to an extend when reaching cruise. When you taxi out and line up you will advance the throttle to full/takeoff power to get in the air. You may then keep it there for your climb or elect for a slightly reduced climb power depending on the situation. You will climb to your cruising altitude and throttle back to between 55% - 75% power for cruise. Fly your flight and at some point you will get where you need to be and throttle back to your decent/landing power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of entering the runway and lining up if you starve the engine when you apply power you are assumed to be either not moving or barely rolling and should be safe. If you pull the power to quickly on decent and stall the engine you may be gliding distance from an airfield and or have time for a restart.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When it happened in cars sometimes you could not restart until the&#xA;  residual fuel was burnt by cranking the engine for some time. Does&#xA;  this apply also to aviation engines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;One neat thing that planes have which most cars done is mixture control. As a result you can pull the mixture control all the way out on a plane (how the plane is shut down), crank the engine, and draw the fuel out of the carb. Some cars will keep pumping fuel and filling up the carb while you crank (since you cant over ride the fuel pump). Generally a flooded car engine you have to wait for it all to evaporate out.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The question arises from the fact that the design of the engines are&#xA;  quite old from my understanding.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Age has little to do with these issues. Fundamentally the internal combustion has changed little since its inception in terms of the way it physically works. While they have gotten far more efficient and reliable the physics are more or less what they have always been. Its our manufacturing technology that has made the engines better. Surging/starving an old engine and surging/starving a new engine will produce a similar issue. Aircrafts use older engines due to the complexity and cost of certifying anything for use in an aircraft. For what its worth Ford has been using the same basic V-8 for as long as some aircraft engines have been around likewise Porsche squeezed a remarkable 30 years out of the same basic air-cooled engine design in the 911 (911 up through 993 variant).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Side Note&lt;/em&gt;: As mentioned its expensive to get a new engine put into service. That being said there are common airplane engines out there (&lt;a href=&quot;https://en.wikipedia.org/wiki/Continental_IO-550&quot; rel=&quot;nofollow&quot;&gt;like the IO-550&lt;/a&gt;) that have fuel injection. As computers become more common place in aviation &lt;a href=&quot;https://en.wikipedia.org/wiki/FADEC&quot; rel=&quot;nofollow&quot;&gt;FADEC&lt;/a&gt; systems are becoming more common in airplanes. In the end of the day however, some of these choices come down to manufacture decisions. Some makers prefer to leave things in the hands of the pilots, in other words you can pull and advance the throttle how ever you like and the fuel/air delivery system will behave as such. Other makers have begun to put safe guards in place to prevent this, and they will (no matter how you operate the throttle) ensure proper advance and retard of all mechanisms as fast as possible should you operate the throttle vigorously.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-01T20:58:46.873" LastActivityDate="2015-12-01T20:58:46.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23305" PostTypeId="2" ParentId="6399" CreationDate="2015-11-30T21:42:48.367" Score="21" Body="&lt;p&gt;Adding to &lt;a href=&quot;https://aviation.stackexchange.com/a/6400/12485&quot;&gt;user2168's answer&lt;/a&gt;, here are some pictures &lt;strong&gt;visualizing the principle of nacelle chines, also called nacell strakes or aerodynamic fan cowl strakes&lt;/strong&gt;.&lt;br&gt;&#xA;Please note that the vortices are always there, but they can only be seen in special conditions, see the end of this answer for an explanation. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mar3e.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mar3e.jpg&quot; alt=&quot;Nacelle chine vortex 1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yVWa5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yVWa5.jpg&quot; alt=&quot;Nacelle chine vortex 2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;YouTube-Video &lt;a href=&quot;https://youtu.be/kSwxJWjHcQM?t=1m2s&quot; rel=&quot;noreferrer&quot;&gt;New Boeing 747-8 Intercontinental Majestic First Flight&lt;/a&gt; by user Altumkell, see the left-side engines of the plane.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;As was stated above, some conditions have to be true if vortices are to be seen:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;To be more precise, the humidity, pressure and temperature of the ambient air has to &quot;match&quot; the pressure drop induced by the nacelle chines/strakes (this pressure drop is due to the flow acceleration, i.e. a higher flow velocity, caused by the nacelle chines/strakes). For passenger aircraft, this is usually the case on humid days not too far above the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Let's assume this is true. In addition, we assume that the air is incompressible, which is usually true for velocities $\mathit{Ma} \leq 0.3$ - which is the case for take-off and landing.&lt;br&gt;&#xA;Now, the increase in flow velocity $c$ caused by the nacelle chines/strakes leads to the decrease of static pressure $p$, which leads to the decrease of static temperature $T$ (the total/stagnation pressure $p_0 \approx p_t$ and total/stagnation temperature $T_0 \approx T_t$ approximately stay constant, $p_0 \approx p_t \approx \mathit{const}$, $T_0 \approx T_t \approx \mathit{const}$).&lt;br&gt;&#xA;If the temperature drops below the local dew point, condensation occurs: the gaseous water vapor transforms into liquid water droplet clouds - this is what can be seen in pictures.&lt;br&gt;&#xA;As a side note: During condensation, the &quot;enthalpy / latent heat of condensation&quot; is released.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Similar effects and explanations can be found e.g. in &lt;a href=&quot;https://aviation.stackexchange.com/questions/21219/how-does-this-vortex-form-inside-a-jet-engine&quot;&gt;How does this vortex form inside a jet engine?&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/19241/why-does-condensation-form-on-the-wing-especially-during-take-off-and-landing&quot;&gt;Why does condensation form on the wing especially during take-off and landing?&lt;/a&gt; and &lt;a href=&quot;https://physics.stackexchange.com/questions/121714/what-caused-a-fluctuating-cloud-to-form-in-a-jet-engine-intake-on-a-humid-day&quot;&gt;What caused a fluctuating cloud to form in a jet engine intake on a humid day?&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Image sources:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/1/0/1/2199101.jpg&quot; rel=&quot;noreferrer&quot;&gt;Nacelle chine vortex 1&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://s3.amazonaws.com/s3.frank.itlab.us/photo-essays/small/apr_01_1240_vortex_dissipation_close.jpg&quot; rel=&quot;noreferrer&quot;&gt;Nacelle chine vortex 2&lt;/a&gt; from &lt;a href=&quot;https://frank.itlab.us/&quot; rel=&quot;noreferrer&quot;&gt;C. Frank Starmer&lt;/a&gt;'s &lt;a href=&quot;https://frank.itlab.us/photo_essays/wrapper.php?apr_01_2010_sq22.html&quot; rel=&quot;noreferrer&quot;&gt;&quot;Photo Adventures with Curiosity and Learning&quot; -- &quot;April 1, 2010:From SIN to EWR with Yen Ping and Kok Mun&quot;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-06T19:51:51.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23306" PostTypeId="1" AcceptedAnswerId="23310" CreationDate="2015-11-30T22:46:29.603" Score="-5" ViewCount="234" Body="&lt;p&gt;What is the lowest height an RPL holding pilot can conduct a circuit? I would like to practice very low circuits to work on my quick thinking. &lt;/p&gt;&#xA;" OwnerUserId="11873" LastEditorUserId="19" LastEditDate="2016-08-05T16:15:37.980" LastActivityDate="2016-08-05T16:15:37.980" Title="What is the lowest allowable circuit height in Australia?" Tags="&lt;altitude&gt;&lt;australia&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23308" PostTypeId="2" ParentId="22850" CreationDate="2015-12-01T00:36:53.453" Score="1" Body="&lt;p&gt;Maybe it is different depending on the airline but airlines typically employee Gate Agents to check passengers in and get the passengers from the boarding area to the aircraft. You will typically not meet the Flight Attendants until you are boarding the aircraft as they have a list of duties they must accomplish before the passengers begin boarding as well as while the passengers are boarding the aircraft. These Gate Agents can sometimes be easily mistaken for Flight Attendants because their uniforms sometimes appear similar. &lt;/p&gt;&#xA;" OwnerUserId="12489" LastActivityDate="2015-12-01T00:36:53.453" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23309" PostTypeId="1" CreationDate="2015-12-01T01:47:13.680" Score="1" ViewCount="380" Body="&lt;p&gt;I've been researching about helicopter flight without a tail rotor and the closest I've found is intermeshing rotors or this: &lt;a href=&quot;https://www.quora.com/Why-dont-helicopters-have-rotor-blades-at-the-bottom&quot; rel=&quot;nofollow&quot;&gt;https://www.quora.com/Why-dont-helicopters-have-rotor-blades-at-the-bottom&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at &lt;a href=&quot;https://youtu.be/2J55KHpgDVM?t=24&quot; rel=&quot;nofollow&quot;&gt;this new method&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seen in this frame, the rotors are single winged and I'm guessing they rotate at opposite phases. What is this called and where can I find more information about it?&lt;/p&gt;&#xA;" OwnerUserId="12490" LastEditorUserId="8730" LastEditDate="2015-12-01T03:56:34.187" LastActivityDate="2015-12-01T05:38:59.110" Title="How is this rotor setup flying?" Tags="&lt;helicopter&gt;&lt;rotorcraft&gt;&lt;vtol&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-12-01T10:03:17.143" ContentLicense="CC BY-SA 3.0" />
  <row Id="23310" PostTypeId="2" ParentId="23306" CreationDate="2015-12-01T04:35:02.740" Score="12" Body="&lt;p&gt;You need to sit down with an instructor, rather than an internet message board, if you are seriously considering such a proposition as this.  Hopefully the instructor can talk you into a little more use of careful, cautious, wise thinking instead of a focus on what you term as &quot;quick thinking&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a place for thinking quickly in aviation, but there is a much more important place for thinking wisely and avoiding unnecessary risks.  &quot;How low can I fly this&quot; doesn't very well fit into the category of wise &amp;amp; prudent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I say this having in my background flying at lower altitudes for longer periods of time than most civilian pilots have been trained for.  Low level navigation at 300' was common in my previous role, but it was NEVER something that you got sent out to figure out by yourself.  You were trained to do it, how to do it well, and what to avoid.  And before each flight, there was some fairly extensive preparation, so that as many &quot;split second&quot; decisions as possible could be made well ahead of time, rather than on the spur of the moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also done some amount of flying (also in the military) where patterns are flown at 500' AGL.  Again, not something that is self-taught.  The big differences involve a lot of changes to the sight-picture, since you are now looking at the runway from an unfamiliar angle.  Can it be learned?  Yes.  Are there things that you need to be taught by people who have more experience than you do?  Absolutely.  Trying to do this on your own is a fairly good recipe for disaster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sit down with an instructor and have this conversation... &lt;em&gt;Please&lt;/em&gt; don't do something foolish based on an answer from an internet forum!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-01T17:14:03.473" LastActivityDate="2015-12-01T17:14:03.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23311" PostTypeId="2" ParentId="23284" CreationDate="2015-12-01T05:01:10.140" Score="3" Body="&lt;p&gt;To better understand the physics of a turn, maybe it helps to look at the centripetal force in a different way. This force is actually pulling the aircraft sideways into the new direction of movement. When banking into the turn on an easterly course, the centripetal force will accelerate the aircraft to the north and, towards the end of the turn, will decelerate its easterly speed, such that it will have a northerly speed when the turn is complete. The centripetal force is the means by which ground speed gets converted from a purely easterly speed to a northerly speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly with 200 kts in a 50 kts headwind and want to fly a northerly track after finishing the turn, you simply stop turning after having decelerated the aircraft by only 150 kts. You don't fly a quarter circle of 90°, but only one of 75.5°; the angle where the cosine has shrunk to 0.25. After that, your easterly speed component is reduced by 150 kts and your northerly speed component has increased to 193.6 kts. When viewed by another plane flying in the same headwind, you have flown a segment of a circle measuring 75.5°. When seen by an observer on the ground, your ground track is a compressed circle segment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting with 250 kts will make you perform the turn at a higher speed, but with the same technique.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Any mistake until now?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes! Your assumption that your ground speed would be 200 kts is wrong. At all times, you will maintain a TAS of 200 kts, and the ground speed after the turn in the first case is only 193.6 kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the second case, you start with a TAS of 250 kts and maintain that over the full turn. Your ground speed after having achieved a northern track is now 242 kts.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The question is how that influence the turning circle?&#xA;  In which of the two cases the turning circle is flatten/stretched and&#xA;  in which is circular if any? What is the approximate shape of them?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That depends on the observer. Your ground track is compressed in easterly direction because you started at an easterly speed component of 150 kts but used the aerodynamic forces of 200 kts for turning. You stopped turning after having yawed the airplane by only 75.5°, so you now fly a correction angle of 14.5° to achieve a purely northern track. The observer will see you accelerate from 150 kts ground speed to 193.6 kts ground speed (and from 200 kts to 242 kts in the second case).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shape of the circle will only look round for an observer flying in the same headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a tailwind, you would keep turning until you have completed a circle segment of 104.5°, so you can let the centripetal force act longer in easterly direction for a ground speed change of 250 kts in easterly direction. Since it will reduce the aircraft's northerly speed component over the last 14.5°, the centripetal force will slow the northerly speed component to 193.6 kts over the last 14.5° of the turn after it had reached 200 kts after turning 90°. Now the ground track is stretched in easterly direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below I added a graph with three ground tracks and airplane symbols overlaid to show the correction angle at the specific point of the turn. All three cases perform a 90° turn and fly initially parallel to the wind direction. I used 50m/s TAS and ±20m/s wind speed; the axes are in meters. The blue line is the case without wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p6fnY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p6fnY.png&quot; alt=&quot;Ground track when turning in wind&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground track when turning in wind (own work). A turn from a headwind course takes much less time and azimuth change than one from a tailwind course. Only the ground track without wind is a circle, all other ground tracks are ellipses. In the headwind case the axis parallel to the wind direction is the shorter axis and in the tailwind case it is the longer of the two axes of the ellipse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you insist on keeping the ground speed constant, you will need to speed up when turning into the wind rsp. to slow down when turning out of the wind. Your second case with 250 KTAS while heading east and 206 kts when flying a northern track is very unusual. &lt;a href=&quot;https://aviation.stackexchange.com/questions/23162/for-light-ga-aircraft-is-there-a-standard-turn-and-what-does-that-mean/23164#23164&quot;&gt;This answer&lt;/a&gt; gives you the basic equations. The time to fly a 75.5° turn with 30° bank angle (= 1.15 g) is $$t_{75.5°} = \frac{v\cdot\pi\cdot75.5°}{g\cdot\sqrt{n_z^2-1}\cdot180°}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which yields 30.4 s for 250 kts (= 118.6 m/s) and 25.1 s for 206 kts, so you will spend 27.75 s turning when the deceleration is linear. The deceleration along the flight path is 0.455 m/s², so you will need to throttle down during the turn and throttle up when the deceleration phase is over. Good luck keeping the ball centered while turning and changing the &lt;a href=&quot;https://aviation.stackexchange.com/questions/15771/what-is-p-factor-in-propeller-aerodynamics/15777#15777&quot;&gt;p-factor&lt;/a&gt; at the same time!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-12-02T12:03:38.683" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23312" PostTypeId="2" ParentId="23309" CreationDate="2015-12-01T05:28:49.307" Score="0" Body="&lt;p&gt;You are right, the two rotors move in opposite direction. This is called a co-axial rotor and is used by the Russian helicopter design bureau &lt;a href=&quot;https://en.wikipedia.org/wiki/Kamov&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kamov&lt;/a&gt;. A co-axial rotor can also be found on many &lt;a href=&quot;http://www.bestindoorrchelicopter.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;model helicopters for indoor flying&lt;/a&gt;. They are a subspecies of helicopters with contra-rotating rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters with contra-rotating rotors do not need a tail rotor and are much easier to fly than Sikorsky-type helicopters, because they suffer much less from instability. This group also comprises intermeshing rotors like those used on &lt;a href=&quot;https://en.wikipedia.org/wiki/Flettner_Fl_282&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flettner&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Kaman_K-MAX&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kaman K-Max&lt;/a&gt; helicopters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sJvKS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sJvKS.jpg&quot; alt=&quot;Kamov Ka-32&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kamov Ka-32 with co-axial rotors operated by HeliSwiss (picture &lt;a href=&quot;http://www.digicamfotos.ch/fotogalerie/data/media/51/_HRE2644_kamov_Ka-32_web.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ruz5S.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ruz5S.jpg&quot; alt=&quot;Kaman K-Max modified as an unmanned vehicle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kaman K-Max with intermeshing rotors modified as an unmanned vehicle (picture &lt;a href=&quot;http://www.operationnels.com/wp-content/uploads/2014/11/K-Max_UAV_drone_umanned_aerial_vehicle_Lockheed_Martin_Kaman_Aerospace_American_United_States_006.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more info, just follow the links.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-01T05:38:59.110" LastActivityDate="2015-12-01T05:38:59.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23313" PostTypeId="1" CreationDate="2015-12-01T06:51:21.913" Score="1" ViewCount="623" Body="&lt;p&gt;Especially at low speed, such as during takeoff, while hovering, and while landing, helicopters are famously difficult (impossible) to control for someone with no experience. Is there a documented instance of any person ever successfully taking off, hovering, and landing a helicopter with no actual flight experience? It must all be in one flight, first time--someone teaching themselves over multiple short flights / hours does not count.  Simulator use is OK and does not count as actual flight experience for the purposes of this question.&lt;/p&gt;&#xA;" OwnerUserId="12492" LastEditorUserId="64" LastEditDate="2016-07-07T21:05:16.243" LastActivityDate="2016-07-07T21:05:16.243" Title="Has anyone successfully solo'd a helicopter with no actual flight experience?" Tags="&lt;flight-training&gt;&lt;flight-simulator&gt;&lt;vtol&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23314" PostTypeId="2" ParentId="23271" CreationDate="2015-12-01T08:36:23.377" Score="2" Body="&lt;p&gt;Turbulence is part and parcel of flying. Rest assured that pilots are trained to handle all types of turbulence in the simulator training. Airplanes are equipped with radar to detect precipitation which usually cause turbulence. &lt;/p&gt;&#xA;" OwnerUserId="12493" LastEditorUserId="1467" LastEditDate="2015-12-03T20:53:01.663" LastActivityDate="2015-12-03T20:53:01.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23315" PostTypeId="2" ParentId="23313" CreationDate="2015-12-01T10:11:25.220" Score="9" Body="&lt;p&gt;Yes, &lt;a href=&quot;https://en.wikipedia.org/wiki/Eric_Brown_(pilot)&quot;&gt;Eric &quot;Winkle&quot; Brown&lt;/a&gt; took delivery of a Sikorsky R-4 and flew it after reading the flight manual and getting a briefing from a USAF Sergeant. He had no experience or training in helicopters. He wrote about it in &quot;Wings of the Weird and Wonderful&quot;. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2015-12-01T10:11:25.220" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23316" PostTypeId="1" AcceptedAnswerId="23319" CreationDate="2015-12-01T10:34:21.693" Score="0" ViewCount="209" Body="&lt;p&gt;How to read this step climb profile?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FL STEPS CYUL/0330/TUDEP/0340/NETKI/0350&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know CYUL is departing point but what do 0330 represents? The altitude in Feet?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2015-12-01T12:36:53.267" Title="How to read this step climb profile? FL STEPS CYUL/0330/TUDEP/0340/NETKI/0350" Tags="&lt;flight-plans&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23318" PostTypeId="1" AcceptedAnswerId="23325" CreationDate="2015-12-01T10:42:54.967" Score="10" ViewCount="6622" Body="&lt;p&gt;I have seen the term &quot;Tropopause height&quot; used in a flight navigation plan. What is it and how is it determined?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="12220" LastEditDate="2016-01-10T19:45:29.257" LastActivityDate="2019-04-25T08:42:26.403" Title="What is Tropopause height, and how is it determined?" Tags="&lt;weather&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23319" PostTypeId="2" ParentId="23316" CreationDate="2015-12-01T10:43:08.710" Score="2" Body="&lt;p&gt;FL330 is the initial cruising altitude after departing CYUL. At TUDEP, a climb to FL340 is planned, and at NETKI, there is another climb to FL350.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-01T12:36:53.267" LastActivityDate="2015-12-01T12:36:53.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23320" PostTypeId="1" AcceptedAnswerId="23324" CreationDate="2015-12-01T10:56:25.777" Score="-2" ViewCount="217" Body="&lt;p&gt;How to read a TAF report which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TAF: VOBL 010800Z 0109/0118 09005KT 6000 SCT010 BKN080 TEMPO 0109/0118 3000 RA/DZ SCT007 SCT012 FEW025CB OVC080 &lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="3394" LastEditDate="2015-12-01T13:25:18.260" LastActivityDate="2015-12-01T13:25:18.260" Title="How to read a TAF report which looks like the following?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-12-01T14:34:27.730" ContentLicense="CC BY-SA 3.0" />
  <row Id="23321" PostTypeId="2" ParentId="23271" CreationDate="2015-12-01T10:58:01.650" Score="7" Body="&lt;p&gt;If all the flight attendants are strapped in, injured, or crying uncontrollably, and preferably all at the same time, then you probably can go off the flight attendants. Maybe. In all other situations you should not. Even if you correctly detect stress it could be for a whole more reasons than the turbulence you are experiencing - because they fly so often, they will have experienced worse, many times before. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this is a good informative article that might help &lt;a href=&quot;http://www.askthepilot.com/questionanswers/turbulence/&quot; rel=&quot;nofollow&quot;&gt;http://www.askthepilot.com/questionanswers/turbulence/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have a trained professional crew up front, who again will have experienced this many many times, they might not be happy about it because they want their passengers to have a smooth ride at all times, but refer to my first sentence before you even worry about the flight crew getting upset or crying also or it affecting their professional judgement in any way whatsoever. Also its far easier in these situations if you are driving than just sat in the back waiting for the next bump. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are on the sea you expect the odd wave and can see it coming, its difficult in the air because you can't see the wave coming. I much prefer sitting in the cockpit myself than sat in the back, in particular if the weather is rough. You would be amazed at how calm it is no matter what the weather (or anything else for that matter). The pilots will be totally relaxed. The only time turbulence will really get their attention is when on approach - the closer you are to the ground when it happens the more attention the pilot will pay to it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember the wings rock when the pilot wants to adjust the direction you are going and the wind often changes more than once on approach (a lot more if its gusty), so its the pilot moving the wings in that case to keep the nose of the aircraft pointing in the right direction because he/she has to do that to change the direction you are heading when the wind blows it off slightly. The wings are used rather than the rudder because its the correct technique, if the rudder was used, now that really would be uncomfortable (and potentially dangerous). Also if the pilot doesn't do this, you will miss the airport by a mile. So what you think is turbulence on approach might be a bit of both - the turbulence itself and the pilot also telling the aircraft exactly where it needs to go. A good game to play is to try to work out which wing rocks are the pilot and which are due to turbulence. The pilot will be smoother (hopefully).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only other thing I would like to add which I hope will help, is that if you watch a video of airliner wings being stress tested, the wingtips more or less have to touch each other before the wing breaks. Not quite perhaps touch but they move a whole lot further than you will ever see in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Severe turbulence can injure people walking around because it could pin them to the roof and then drop them to the floor the next second. Thats why you have the seatbelt signs on at the first sign of turbulence. However, even if this happened and dozens of passengers were injured in this way, the aircraft would be totally undamaged. Obviously something the pilots will try their best to avoid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this answer helps. Please just relax and enjoy the ride, aircraft are not designed to fall apart in the air the first bump that comes along, they fly for thousands of hours in situations like this and sometimes pilots just can't avoid the turbulence if its one of those days where its everywhere!&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-12-02T17:09:59.873" LastActivityDate="2015-12-02T17:09:59.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23324" PostTypeId="2" ParentId="23320" CreationDate="2015-12-01T12:41:58.343" Score="6" Body="&lt;p&gt;You can find &lt;a href=&quot;https://www.aviationweather.gov/static/help/taf-decode.php#Forecast&quot;&gt;how to decode TAF&lt;/a&gt; at aviationweather.gov site. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A TAF report usually contains the following sequence of elements:   &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Type of Report&lt;/li&gt;&#xA;&lt;li&gt;ICAO Station Identifier&lt;/li&gt;&#xA;&lt;li&gt;Date and Time of Origin&lt;/li&gt;&#xA;&lt;li&gt;Valid Period Date and Time&lt;/li&gt;&#xA;&lt;li&gt;Forecast Meteorological Conditions &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;TAF- Type of report&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOBL- ICAO station identifier&lt;/p&gt;&#xA;&#xA;&lt;p&gt;010800Z- Date and time of origin&lt;/p&gt;&#xA;&#xA;&lt;p&gt;0109/0118- Valid period date and time&lt;/p&gt;&#xA;&#xA;&lt;p&gt;09005KT- Wind&lt;/p&gt;&#xA;&#xA;&lt;p&gt;6000- Visibility in metres&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SCT010 BKN080- Thousand scattered, ceiling eight thousand broken cumulonimbus clouds &lt;/p&gt;&#xA;&#xA;&lt;p&gt;TEMPO - Is used to denote temporary conditions which may arise, followed by the forecasted meteorological conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;0109/0118- between these times&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3000- Visibility in metres&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SCT007 SCT012- Same as above&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="524" LastEditDate="2015-12-01T12:43:47.737" LastActivityDate="2015-12-01T12:43:47.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23325" PostTypeId="2" ParentId="23318" CreationDate="2015-12-01T13:00:26.243" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Tropopause#Definition&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to Wikipedia&lt;/a&gt;, the World Meteorological Organization defines tropopause as&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The boundary between the troposphere and the stratosphere, where an abrupt change in lapse rate usually occurs. It is defined as the lowest level at which the lapse rate decreases to 2&amp;nbsp;˚C/km or less, provided that the average lapse rate between this level and all higher levels within 2&amp;nbsp;km does not exceed 2&amp;nbsp;˚C/km. Occasionally, a second tropopause may be found if the lapse rate above the first tropopause exceeds 3&amp;nbsp;˚C/km.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The tropopause height varies with latitude and season. The variation with latitude, based on annual mean conditions, is shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9m5la.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9m5la.gif&quot; alt=&quot;Troposphere height&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Image from &lt;a href=&quot;http://das.uwyo.edu/~geerts/cwx/notes/chap01/tropo.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;das.uwyo.edu&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Troposphere can be identified only if the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lapse_rate&quot; rel=&quot;nofollow noreferrer&quot;&gt;lapse rates&lt;/a&gt; (the rate at which atmospheric temperature decreases with increase in altitude) in the stratosphere and troposphere are known. Also, weather phenomena like thunderstorms shift the tropopause. As a result, the height of the tropopause is forecast based on localized weather conditions, and is not a fixed boundary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The International Standard atmosphere, however, defines tropopause as lying between ~11,000 and 20,000 meters (geopotential altitude) above MSL.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2143" LastEditDate="2015-12-05T17:48:54.180" LastActivityDate="2015-12-05T17:48:54.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23326" PostTypeId="1" CreationDate="2015-12-01T14:13:25.467" Score="2" ViewCount="657" Body="&lt;p&gt;I tried to calculate drag for hyper velocity project using &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710026940.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this paper&lt;/a&gt; for Sears Haack revolution body. Some parameters:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Diameter: 160mm (round number for simulating 155mm projectile)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fineness ratio: 13.2, which means projectile's length is 2112mm&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the paper, the assumed wing area &lt;span class=&quot;math-container&quot;&gt;$S$&lt;/span&gt; is &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$0.077 \cdot l^2 = 0.077 \cdot (2.112)^2 = 0.3435 \ [m^2]$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Figure 15 in the paper, the total Cd at 2km/s is about 0.004&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So total drag at sea level &#xA;&lt;span class=&quot;math-container&quot;&gt;$$D = 0.5 \cdot v^2 \cdot \rho \cdot S \cdot C_D$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$D = 0.5 \cdot 2000^2 \cdot 1.23 \cdot 0.3435 \cdot 0.004 = 3380 \ [N]$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the paper, the volume &lt;span class=&quot;math-container&quot;&gt;$V$&lt;/span&gt; of the projectile is&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$V = 0.002655 \cdot l^3 = 0.025 \ [m^3]$$&lt;/span&gt;&#xA;Assume it is filled with aluminum, then the mass &lt;span class=&quot;math-container&quot;&gt;$m$&lt;/span&gt; is about &#xA;&lt;span class=&quot;math-container&quot;&gt;$$ 0.025 \cdot 3000 = 75 \ [kg]$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the drag is about 4.5g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, there is an empirical formula for hypersonic lift to drag ratio is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{L}{D} = \frac{4 \cdot (M + 3)}{M} = \frac{4 \cdot (6 + 3)}{6} = 6$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that if the projectile is shaped as a good waverider then drag can be as low as 1/6 of its weight, assuming the waverider is the best shape for hypersonic lift to drag ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is of course the problem about scaling where mass is increased at cubed speed, while area only increases at squared speed. While I don't have an complete computational model of waverider to compare directly with SH body, but it seems at the first glance, the waverider can get much lower drag than even the most aerodynamic shape, 1/6g vs 4.5g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is it true that the waverider has much lower drag than a SH body?&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="4197" LastEditDate="2020-06-01T11:50:57.213" LastActivityDate="2020-06-01T11:50:57.213" Title="Does waverider have much lower drag than Sears Haack body?" Tags="&lt;drag&gt;&lt;hypersonic&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23327" PostTypeId="1" CreationDate="2015-12-01T15:06:28.117" Score="4" ViewCount="3277" Body="&lt;p&gt;I think the drag of the engine is high, for most type of engine, e.g turbo fan, jet, ramjet... I guess the engine's drag is worse than a flat plate of the same area perpendicular to air stream because the engine slows the air and compress it, and also the engine has many components inside it that will interact with air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A flat plate is very bad aerodynamically and so the engine. Even small landing wheel should be folded inside body for better drag. So an aircraft with engines turned off will have very high drag, but I can not find any estimation on this matter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, an aircraft that has L/D about 15, how about its drag if engine is removed, e.g. for better glide ratio when engine failure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you estimate this drag?&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="69" LastEditDate="2015-12-02T03:39:35.493" LastActivityDate="2015-12-02T03:39:35.493" Title="About how much drag does a non-operating engine create?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;engine&gt;&lt;drag&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23328" PostTypeId="2" ParentId="16034" CreationDate="2015-12-01T15:08:06.133" Score="3" Body="&lt;p&gt;To expand on an earlier answer at some towers Controllers use prominent landmarks in the distance to give a rough guide to RVR. They know if they can or cannot see a particular building what the RVR is. This is only used as a last resort when equipment malfunctions, but it works.&lt;/p&gt;&#xA;" OwnerUserId="12498" LastActivityDate="2015-12-01T15:08:06.133" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23329" PostTypeId="2" ParentId="23326" CreationDate="2015-12-01T16:49:22.563" Score="7" Body="&lt;p&gt;A waverider will prevent the compressed air under the airframe from escaping sideways. An equivalent view is that the sideways component of the air displaced by the body is used for lift creation by straightening it and pushing it down at the wingtips. This allows it to fly at a lower angle of attack for the same lift, which reduces supersonic lift-related drag linearly with the reduction in angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drag of a Sears-Haack body is the lowest for a given volume and a given fineness ratio. Increasing the fineness (essentially, the local inclination times the circumference of each body section) will reduce drag. This increased fineness, however, will now cause less sideways displacement of airflow which could be used for the waverider effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, the question as asked is not answerable. What can be said is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A blunt Sears-Haack body will profit the most from the waverider effect.&lt;/li&gt;&#xA;&lt;li&gt;A waverider is still a Sears-Haack body if it has the right cross section distribution over length.&lt;/li&gt;&#xA;&lt;li&gt;A waverider will maybe lower drag by 20% or 30% in a realistic configuration and at Mach numbers between Mach 3 to 5.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The empirical equation for the L/D of a waverider looks suspicious. Without knowing the constraints of its validity, I would not trust its results. Also, the drag coefficient of your Sears-Haack body looks like the zero-lift drag. You might need to add the lift-related drag to arrive at the complete drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the biggest mistake is to operate it at ground level - 2000 m/s would be appropriate in 30 km altitude. Get the drag figure there and you will arrive at a much lower drag just by operating it in the appropriate density.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-01T21:42:26.303" LastActivityDate="2015-12-01T21:42:26.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23330" PostTypeId="2" ParentId="23327" CreationDate="2015-12-01T16:54:58.057" Score="2" Body="&lt;p&gt;There has been &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1948/naca-rm-e8j25a.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;some studies carried out&lt;/a&gt; for calculating the windmilling drag (of turbojet) engines and these indicate that the windmilling drag is in the order of 10% of the net thrust. In modern high-bypass turbofan engines, the figure will probably be higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150002109.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA simulations&lt;/a&gt; estimate the baseline drag coefficient of engine for a medium sized aircraft as 0.31, with additional drag based on Mach number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bc7gW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bc7gW.png&quot; alt=&quot;Windmilling&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drag due to windmilling, Image from &lt;em&gt;Validation of an Integrated Airframe and Turbofan Engine Simulation for Evaluation of Propulsion Control Modes&lt;/em&gt; by Jonathan Litt et. al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of studies that deal with the windmilling characteristics of turbojet engines. In general, the effect of removal engine drag in the baseline L/D will not be very high in all probability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're also &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1948/naca-rm-e8j25a.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;correct that the drag is more in case of windmilling&lt;/a&gt; compared to locked rotor. The drag in that case is in the order of 40% of the windmilling engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are multiple problems with the premise that the engines would've to be dropped in case of engine failure.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine failure is pretty rare for a system like engine jettison to be incorporated. In addition to the weight increase, there is the problem uncommanded operation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircrafts are certified for OEI condition. Nobody is going to drop a costly engine (note that multiple engine failures are extremely rare) because it stopped due to a minor problem. Better to fix it once the aircraft touches down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even after all this , where are you going to drop the engine? unless it is over the ocean, there is no certainty that the falling engine will not cause any damage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Assuming you drop the engine and it doesn't damage the aircraft, you've to trim the aircraft to adjust for the new c.g.  Also, aircraft will be unbalanced if you drop one of the engines, requiring more control force. Also, the wing twist will increase and the wing will bend up.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-01T16:54:58.057" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23331" PostTypeId="2" ParentId="23327" CreationDate="2015-12-01T17:21:36.300" Score="3" Body="&lt;p&gt;An inoperative engine creates much less drag than a flat plate of the same cross section. According to Sighard Hoerner's &lt;a href=&quot;https://docs.google.com/file/d/0Bx0MqOfev7dnTnB0eFRIN2JQb0k/edit?pli=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fluid Dynamic Drag&lt;/a&gt;, the drag coefficient of a flat plate is 1.17. An engine nacelle has rounded intake lips which help the flow to stay attached while flowing around the nacelle. The closest of the generic bodies in the table below would be the sphere (drag coefficient of 0.47).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zL0l2.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zL0l2.png&quot; alt=&quot;Figure 33 from Sighard Hoerner&amp;#39;s Fluid Dynamic Drag, Chapter 3&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure 33 from Sighard Hoerner's Fluid Dynamic Drag, Chapter 3. Left column: Bodies of rotation; right column: Cross sections of 2D-bodies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much depends on the detail of flow separation at the forward corner, and here modern engines are rather good. If the flow stays attached, drag will be much lower than with the massive separation around and behind the flat plate. Air flowing out from the inside and over the corner of the flat plate will need some space to &quot;turn around&quot;, effectively increasing the blocked cross section that the outside flow experiences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the reference area for all values here is the cross section of the body perpendicular to the flow, while the reference area for airplanes is their wing area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the type, the diameter of one &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2739831/&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE90 engine is 134 or 135 inches&lt;/a&gt;. Two of those power a Boeing 777 which &lt;a href=&quot;http://www.civilaviation.eu/Boeing/777-200.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;has a wing area of 427.8 m²&lt;/a&gt;. The ratio of engine frontal area to wing area is thus 1/23.335. The (estimated) drag coefficient of the nacelle of 0.5 would shrink to 0.0214 when referenced to the wing area. This would increase the total drag by about 50%, so instead of an L/D of 18 without engines, the airplane would have an L/D of 12 with inoperative engines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-01T17:21:36.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23332" PostTypeId="2" ParentId="23264" CreationDate="2015-12-01T19:48:11.997" Score="3" Body="&lt;p&gt;All manufacturers have a quality system in place, and they also have a production baseline (which is a result of certification). so, as long as the quality system is utilized, there is technically no need to fly each manufactured airplane. Type certification validates the production baseline (and that each manufactured plane is within the tolerances acceptable for the certification authority or requirements). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, depending on company manufacturing know how (or lack of) there might be several ground tests (structural, engine, systems checkout) before delivery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, for many military aircraft there's a factory checkout flight, to check and confirm the performance of each frame and propulsion system. This is more useful for risk reduction (to avoid customer complaints and to check the complex system in the air). &lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-12-01T19:48:11.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23333" PostTypeId="2" ParentId="23318" CreationDate="2015-12-01T20:04:19.033" Score="10" Body="&lt;p&gt;The tropopause height varies with latitude and season.  Its height can be determined by looking at an atmospheric sounding as temperatures in the stratosphere increase with height.  This also means there is a strong static stability gradient at the tropopause.  The height can also be defined by a specific value of potential vorticity units (e.g. the 1.5 PVU surface).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a current sounding from a balloon launched this morning at 12Z:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/gRQxg.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gRQxg.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here you can see a sharp transition in temperature lapse rate at about 200 mb between 11 and 12 km height.  Where the temperatue begins to rise with height (the kink around 200mb) is where the tropopause is located.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-01T20:04:19.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23334" PostTypeId="2" ParentId="23271" CreationDate="2015-12-01T20:22:48.043" Score="10" Body="&lt;p&gt;When I was in training, we had specific explanations on the effects of the different levels of turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Light turbulence:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Pilot's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Turbulence that momentarily causes slight erratic changes in altitude and/or attitude (pitch, roll and yaw).&lt;br /&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Passenger's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Occupants may feel a slight strain against seat belts or shoulder straps. Unsecured objects may be displaced slightly. Food service may be conducted and little or no difficulty is encountered in walking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Moderate turbulence&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Pilot's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed.&lt;br /&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Passenger's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Occupants feel definite strains against seat belts or shoulder straps. Unsecured objects are dislodged. Food service and walking are difficult.&lt;br /&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Severe turbulence&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Pilot's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control.&lt;br /&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Passenger's point of view:&lt;/em&gt;&lt;br /&gt;&#xA;Occupants are forced violently against seat belts or shoulder straps.&#xA;Unsecured objects are tossed about. Food Service and walking are impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To comment on the &quot;going around&quot; for another attempt. This is always ok. Perfectly normal. There can be countless reasons why this might happen.&#xA;And when it happens, the captain has decided that it is safer to go around than to continue.&lt;br /&gt;&#xA;The only place turbulence may be a problem is close to the ground (ie. on approach to land). If there is a sudden downdraught close to the ground, there may not be enough height to recover. This has happened in the past due to a microburst but most modern airports now have specific radar designed to detect these phenomena.&lt;/p&gt;&#xA;" OwnerUserId="6754" LastEditorUserId="6754" LastEditDate="2015-12-03T20:50:48.633" LastActivityDate="2015-12-03T20:50:48.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23335" PostTypeId="1" CreationDate="2015-12-01T21:04:55.493" Score="5" ViewCount="2568" Body="&lt;p&gt;I'm wondering if there is any formal/official definition* pertaining to the &lt;strong&gt;title given to people controlling Unmanned Aerial Vehicles?&lt;/strong&gt; Are they &quot;more&quot; correctly titled Operators or Pilots?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*As set by ICAO, EASA or FAA for instance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Examples:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theguardian.com/world/2015/nov/18/life-as-a-drone-pilot-creech-air-force-base-nevada&quot; rel=&quot;nofollow&quot;&gt;The Guardian&lt;/a&gt;: &quot;Life as a drone operator&quot;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.airforcetimes.com/story/military/careers/air-force/enlisted/2015/09/28/enlisted-drone-pilots-decision-expected-early-next-year/72806812/&quot; rel=&quot;nofollow&quot;&gt;Air Force Times&lt;/a&gt;: &quot;Enlisted drone pilots? Decision expected early next year&quot;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I've had a look through &lt;a href=&quot;http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:079:0001:0049:EN:PDF&quot; rel=&quot;nofollow&quot;&gt;EASA Directive 2009/48/EC&lt;/a&gt; where it states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Operator&lt;/strong&gt; shall mean any legal or natural person, operating&#xA;  or proposing to operate one or more aircraft;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That does not provide a distinction between the entity organizing (e.g. airline) and the actual person doing the flying. A commercial pilot will not title himself an &quot;aircraft operator&quot; but will call themselves a pilot. This is less well defined with UAVs.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="62" LastEditDate="2015-12-02T14:25:35.470" LastActivityDate="2017-06-11T05:12:07.270" Title="Should people flying UAVs be called &quot;Operators&quot; or &quot;Pilots&quot;?" Tags="&lt;pilots&gt;&lt;unmanned-aerial-vehicle&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23337" PostTypeId="1" AcceptedAnswerId="23343" CreationDate="2015-12-01T22:36:15.037" Score="3" ViewCount="1607" Body="&lt;p&gt;In a &lt;a href=&quot;https://www.youtube.com/watch?v=6gVDQi9K0G8&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt;, a Swiss International Air Lines crew flies an Airbus A340-313 (flight LX38) from Zurich to San Francisco. Then, they can be seen (&lt;em&gt;I am not sure if this is on the very same day&lt;/em&gt;) visiting downtown and the Golden Gate prior to getting back to the airport for the return flight (LX39), which is scheduled for departure around three hours later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question here is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do airlines handle crew turnovers in long-haul flights? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it the same crew who is demanded to command the return flight? Or is there, oddly enough, a replacement crew in each destination airport? Or do they carry the crew for flight LX39 onboard flight LX38?&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="11885" LastEditDate="2015-12-02T09:40:07.353" LastActivityDate="2015-12-02T09:40:07.353" Title="How do airlines provide crews for the return leg of a long-haul flight?" Tags="&lt;crew&gt;&lt;flight-schedules&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23338" PostTypeId="2" ParentId="23335" CreationDate="2015-12-01T22:44:49.717" Score="5" Body="&lt;p&gt;The oxford dictionary &lt;a href=&quot;http://www.oxforddictionaries.com/definition/english/pilot&quot; rel=&quot;nofollow noreferrer&quot;&gt;defines pilot&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A person who operates the flying controls of an aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, technically, the drone operator should be called a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA National Policy &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgOrders.nsf/0/10947cee0052205886257bbe0057bd76/$FILE/8130.34C.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Order 8130.34C Airworthiness Certification of Unmanned Aircraft Systems and Optionally Piloted Aircraft&lt;/a&gt; Section 6 specifically calls the person operating the UAS (only if it has been issued with an airworthiness certificate ) Pilot.:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;6&quot;&gt;&#xA;  &lt;li&gt;UA Pilots and Observers.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;a. PIC Roles and Responsibilities.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The PIC must perform crew duties for only one UA at a time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) All UA flight operations must have a designated PIC. The PIC has responsibility over each flight conducted and is accountable for the UA flight operation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The PIC is responsible for the safety of the UA as well as persons and property along the UA flight path. This includes, but is not limited to, collision avoidance and the safety of persons and property in the air and on the ground.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) The PIC must avoid densely populated areas and congested airways in accordance with § 91.319.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The order requires the PIC to have a minimum of FAA PPL:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;b. UA PIC Certification and Ratings Requirements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The PIC must hold and be in possession of, at a minimum, an FAA private pilot certificate, with either an airplane, rotorcraft, or powered-lift category; with single- or multiengine class ratings, appropriate to the type of UA being operated.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The PIC must have and be in possession of a valid second-class (or higher) airman medical certificate issued under 14 CFR part 67, Medical Standards and Certification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;UK CAA also &lt;a href=&quot;http://www.caa.co.uk/default.aspx?catid=1995&amp;amp;pageid=11190&quot; rel=&quot;nofollow noreferrer&quot;&gt;talks about&lt;/a&gt; 'Pilot Qualifications required to operate Unmanned Aircraft'. ICAO also uses the term 'pilot' for people controlling an UAV.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Both USAF and RAF call the UAV operators pilots- RAF calls them &lt;a href=&quot;https://www.raf.mod.uk/recruitment/roles/roles-finder/aircrew/remotely-piloted-aircraft-system-rpas-pilot/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Remotely Piloted Aircraft System Pilots&lt;/a&gt; and USAF, Remotely Piloted Aircraft Pilots and they do get the 'wings'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o7h7R.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o7h7R.jpg&quot; alt=&quot;RPA wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:United_States_Air_Force_Unmanned_Aircraft_Operator_Badge.jpeg#/media/File:United_States_Air_Force_Unmanned_Aircraft_Operator_Badge.jpeg&quot; rel=&quot;nofollow noreferrer&quot;&gt;United States Air Force Unmanned Aircraft Operator Badge&lt;/a&gt;&quot; by SSgt Austin May of the USAF - &lt;a href=&quot;http://www.af.mil/news/story.asp?id=123170151&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.af.mil/news/story.asp?id=123170151&lt;/a&gt;&lt;a href=&quot;http://www.mildenhall.af.mil/news/story.asp?id=123170577&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.mildenhall.af.mil/news/story.asp?id=123170577&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there has been no UAV pilot license issued as far as I know.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-01T22:53:52.343" LastActivityDate="2015-12-01T22:53:52.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23340" PostTypeId="2" ParentId="23337" CreationDate="2015-12-02T01:31:52.330" Score="3" Body="&lt;p&gt;USA, EU, as well as other countries, have set law to regulate daily duty hour. Both the actual flight time for pilots and time of gap between shift have been limited. In USA,the rule has been tightened after &lt;a href=&quot;https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407&quot; rel=&quot;nofollow&quot;&gt;Colgan Air Flight 3407 incident&lt;/a&gt; .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the airlines rent hotel nearby the airport of long-haul destination for the cabin crew and pilot. Usually the airlines will schedule the crew to service the return flight for next day. The crew often receive extra bonus (in terms of local currency) from the airlines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Special immigration policy are set for air crew, many countries are allowed to air crew entry with via crew certificate and on duty, regardless the general immigration and visa policy. On the other hand, some countries have introduced Crew Visa System such as USA(C-1/D visa).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes the air crews, especially the pilot, are requested to travel to other destinations as passengers by another flight. It depends on the airlines' schedules. In such case the off-duty crews may also travel by freighters, like &lt;a href=&quot;https://en.wikipedia.org/wiki/El_Al_Flight_1862&quot; rel=&quot;nofollow&quot;&gt;El Al Flight 1862 incident&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2015-12-02T01:47:50.897" LastActivityDate="2015-12-02T01:47:50.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23341" PostTypeId="1" CreationDate="2015-12-02T03:40:37.650" Score="21" ViewCount="21506" Body="&lt;p&gt;Today, at my part 141 flight school I failed a stage check (flight test), because I did not perform a hold. I'm in com-multi training and was shooting a single engine approach in a Beechcraft Baron. I was inbound from the SSW preparing to shoot the GPS 01 approach. I knew the AUGIE route said &quot;no pt&quot;, however, because I was a straight in approach, I believed that the hold was not required. So I started the approach at the BEJCY (IAF) rather than turning off course. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The examiner failed me right then and there. After the flight, he told me the ONLY time a hold/procedure turn is not required is where a &quot;no pt&quot; route is published. &#xA;Aren't there other circumstances that relieves a mandatory hold/pt? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MMA6n.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MMA6n.jpg&quot; alt=&quot;GPS01&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="69" LastEditDate="2015-12-02T04:04:49.283" LastActivityDate="2019-06-08T18:05:17.387" Title="When are procedure turns not required?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23342" PostTypeId="2" ParentId="23341" CreationDate="2015-12-02T03:47:28.083" Score="18" Body="&lt;p&gt;The correct thing to do very much depends on the clearance that you were given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were simply cleared direct to BEJCY and cleared for the approach, then your instructor is correct and you should have completed the procedure turn as charted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the &lt;strong&gt;clearance&lt;/strong&gt; included the words &lt;em&gt;straight in&lt;/em&gt; (i.e. &quot;cleared for the straight in GPS 01 approach&quot;), then you could not perform the procedure turn even if you wanted to, without getting permission first.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are receiving radar vectors to final (i.e. &quot;Fly heading xxx, cleared for the GPS 01 approach&quot;) or if you are doing a timed approach from a holding fix then you may not perform the procedure turn either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also charts which have notes saying &quot;NOPT for arrivals between radials xxx and xxx.&quot; or similar, which would also preclude you from performing the procedure turn under the appropriate conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By default, the procedure turn is required if depicted unless there is a specific reason not to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5 − 4 − 9. Procedure Turn and Hold − in − lieu of Procedure Turn &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. A&#xA;  procedure turn is the maneuver prescribed when it is necessary to&#xA;  reverse direction to establish the aircraft inbound on an intermediate&#xA;  or final approach course. The procedure turn or hold−in−lieu−of−PT is&#xA;  a required maneuver when it is depicted on the approach chart, unless&#xA;  cleared by ATC for a straight−in approach. Additionally, the procedure&#xA;  turn or hold−in−lieu−of−PT is not permitted when the symbol “No PT” is&#xA;  depicted on the initial segment being used, when a RADAR VECTOR to the&#xA;  final approach course is provided, or when conducting a timed approach&#xA;  from a holding fix. The altitude prescribed for the procedure turn is&#xA;  a minimum altitude until the aircraft is established on the inbound&#xA;  course. The maneuver must be completed within the distance specified&#xA;  in the profile view. For a hold−in−lieu−of−PT, the holding pattern&#xA;  direction must be flown as depicted and the specified leg&#xA;  length/timing must not be exceeded. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE − &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The pilot may elect to use&#xA;  the procedure turn or hold −in−lieu−of−PT when it is not required by&#xA;  the procedure, but must first receive an amended clearance from ATC.&#xA;  If the pilot is uncertain whether the ATC clearance intends for a&#xA;  procedure turn to be conducted or to allow for a straight −in&#xA;  approach, the pilot must immediately request clarification from ATC&#xA;  (14 CFR Section 91.123).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-12-02T04:06:28.130" LastActivityDate="2015-12-02T04:06:28.130" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23343" PostTypeId="2" ParentId="23337" CreationDate="2015-12-02T07:19:16.210" Score="8" Body="&lt;p&gt;You presume that they flew back the very same day... but that is an incorrect presumption. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For long flights over about 8 hours, strict rest limits apply so they cannot fly again for 8-10 hours at a bare minimum. Typically, a crew from a long-haul flight will stay in a hotel in the destination city for anywhere from 12 to 48 hours, depending on the flight length, timezone changes, airline schedules, union contracts, and so on. Yes the hotels and travel bonuses costs the airline a pretty penny but that's the cost of doing business. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So at this very moment there will be 1 or maybe 2 LX crews, resting (or touristing...) in San Francisco, waiting to fly a return service. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information you can google or ask a new question on Fatigue Risk Management Systems. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-12-02T07:19:16.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23344" PostTypeId="2" ParentId="23337" CreationDate="2015-12-02T07:33:14.693" Score="2" Body="&lt;p&gt;For long routes, quite often the crew of the outbound leg is not the same as the crew on the inbound leg.&lt;br/&gt;&#xA;For example the way KLM does it (or used to) to Curacao where there were 3 flights a week, they'd have the crew fly Amsterdam-Curacao, then have a few days off on the island before taking the next aircraft back, the crew of which would then have a few days off.&lt;br/&gt;&#xA;&lt;br/&gt;&#xA;Depending on the destination city the route may be more or less desired by crews obviously, some places are much nicer to spend a few days on company time than others :)&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-12-02T07:33:14.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23345" PostTypeId="1" AcceptedAnswerId="23349" CreationDate="2015-12-02T09:57:44.273" Score="13" ViewCount="1305" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/23341/when-are-procedure-turns-not-required&quot;&gt;From this question&lt;/a&gt;.  I am not instrument rated.  The answers to the question explain, from the point of view of the plate instructions, if a PT is required or not.  The OP was failed for not performing a hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I can't see why a turn or hold is required at all.  If you are approaching within say 30 degrees, why would you not simply turn onto the final approach course and fly the approach (assuming that you are cleared of course)?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you were simply cleared direct to BEJCY and cleared for the approach, then your instructor is correct and you should have completed the procedure turn as charted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The OP was approaching from SSW from AUGIE so continuing to BEJCY puts him 21 degrees to the South.  Why not just turn right onto 007?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am assuming no ATC instructions to do anything other than the published approach.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-12-03T03:09:56.460" Title="Why is a procedure turn required if you are more or less on the final approach course?" Tags="&lt;faa-regulations&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23346" PostTypeId="2" ParentId="23284" CreationDate="2015-12-02T11:50:52.893" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bOB9I.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bOB9I.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you maintain a constant bank angle (30 degrees for a 1.15 g turn) and maintain constant true airspeed of 200 Knots, your path will be as shown in the chart by the yellow line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you maintain a constant ground speed (150 knots) and a constant acceleration 1.15, then your path will be as described by the grey line. It will be as if there is no wind, however it requires thrust variations and bank angle variations. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-12-02T11:50:52.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23347" PostTypeId="1" AcceptedAnswerId="23656" CreationDate="2015-12-02T13:17:57.633" Score="12" ViewCount="3574" Body="&lt;p&gt;The KNKT's &lt;a href=&quot;http://kemhubri.dephub.go.id/knkt/ntsc_aviation/baru/Final%20Report%20PK-AXC.pdf&quot; rel=&quot;noreferrer&quot;&gt;final report on last year's Air Indonesia QZ-8501 crash&lt;/a&gt; repeatedly mentions that the faulty solder joint on the Flight Augmentation Computer (FAC) caused an open circuit on &amp;quot;both channel A and B&amp;quot;, leading to the repeated failure of the Rudder Travel Limiter Unit (RTLU). (Page 66 of the report has a photo of the offending solder joint and of the whole module.)&lt;/p&gt;&#xA;&lt;p&gt;What are these &amp;quot;channels&amp;quot;? The only relevant mention I can find in the report is on p37, an extract from the Flight Crew Operation Manual, as follows (ellipsis mine):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In performing these functions the FAC uses independent channels:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Yaw damper&lt;/li&gt;&#xA;&lt;li&gt;Rudder trim&lt;/li&gt;&#xA;&lt;li&gt;Rudder travel limit&lt;/li&gt;&#xA;&lt;li&gt;Flight envelope&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;...&lt;br /&gt;&#xA;If  a  failure  is  detected  on  any  channel  of  FAC1,  FAC2  takes&#xA;over the corresponding channel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Are the &amp;quot;channels A and B&amp;quot; two of the output &amp;quot;channels&amp;quot; mentioned here? The last quoted line suggests that each channel is redundant between the two computers, in which case why would both RTLUs fail together?&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-14T23:51:19.927" Title="What are the &quot;channels&quot; on the A320 Rudder Travel Limit Unit?" Tags="&lt;avionics&gt;&lt;airbus-a320&gt;&lt;fly-by-wire&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23348" PostTypeId="1" AcceptedAnswerId="23350" CreationDate="2015-12-02T13:43:07.040" Score="13" ViewCount="2290" Body="&lt;p&gt;The &lt;a href=&quot;http://edition.cnn.com/2015/12/01/asia/air-asia-crash-report/&quot;&gt;recent reports&lt;/a&gt; about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Indonesia_AirAsia_Flight_8501&quot;&gt;Air Asia Flight 8501 crash&lt;/a&gt; mention that the plane was stalled and that the pilots could not recover from the stall. Indonesia's National Transport Safety Committee apparently had this to say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Subsequent flight crew action resulted in inability to control the aircraft ... causing the aircraft to depart from the normal flight envelope and enter a prolonged stall condition that was beyond the capability of the flight crew to recover.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Online information that I could find suggests that Airbus pilots were not required to learn stall-recovery and other &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_upset&quot;&gt;upsets&lt;/a&gt; recovery as part of training, due to the aircrafts &quot;inability&quot; to enter those conditions. This may have changed, at least for stall recovery, at some airlines, after the crash of &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Air France Flight 447&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is stall recovery mandatory training for Airbus pilots?&lt;/strong&gt; Was it ever not mandatory? How about for pilots of Boeing, Embraer, and other large passenger aircraft?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="1467" LastEditDate="2016-05-20T06:53:47.000" LastActivityDate="2016-05-20T06:53:47.000" Title="Is stall recovery training mandatory for Airbus pilots?" Tags="&lt;flight-training&gt;&lt;pilots&gt;&lt;regulations&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23349" PostTypeId="2" ParentId="23345" CreationDate="2015-12-02T14:22:55.313" Score="17" Body="&lt;p&gt;Read that other question again.  He was approaching from the SSW and made an assumption based on the approach segment from AUGIE.  He wasn't actually on the AUGIE-BEJCY leg as it would be impossible to be there if he were approaching from the SSW.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;His clearance was &quot;Direct BEJCY cleared for the GPS 01 approach&quot;.  That clearance, in lieu of any specific instructions about the procedure turn, requires that the procedure turn be flown.  He assumed that because he was roughly on the extended centerline of the runway SSW of the airport that he was exempt.  However, there is no charted course there labelled &quot;NoPT&quot;, so his assumption was incorrect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Back to your question of why someone flying from that location would have to fly the PT, and the answer generally boils down to &quot;&lt;a href=&quot;http://www.fredonflying.com/Articles/IFR_Refresher/1107-The-Truth-About-TERPS.pdf&quot; rel=&quot;noreferrer&quot;&gt;TERPS&lt;/a&gt;&quot;.  The leg from AUGIE can be flown at 3000 ft while the area minimum safe altitude is 3100 ft.  It is very likely the minimum enroute altitude over that area is higher than 3100 feet.  This means a pilot that is using BEJCY as the IAF may be considerably higher altitude than 3000 ft.  On this approach you ideally want to be at 2500 ft by the FAF at CUCTO.  If you are approaching BEJCY from any direction other than AUGIE this means you cannot start your descent from whatever altitude you are at down to 2500' until passing BEJCY.  The procedure turn is not only for course alignment but also to descend to the procedure altitude from the enroute environment.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="938" LastEditDate="2015-12-03T03:09:56.460" LastActivityDate="2015-12-03T03:09:56.460" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23350" PostTypeId="2" ParentId="23348" CreationDate="2015-12-02T14:28:15.240" Score="6" Body="&lt;p&gt;Stall training is mandatory for all pilots operating under CFR 121, albeit in a simulator. According to 14 CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3703f49be85e3e6571536c884c339cc0&amp;amp;mc=true&amp;amp;node=se14.3.121_1423&amp;amp;rgn=div8&quot;&gt;§121.423 Pilot: Extended Envelope Training&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Each certificate holder must include in its approved training program, the extended envelope training set forth in this section with respect to each airplane type for each pilot. The extended envelope training required by this section must be performed in a Level C or higher full flight simulator, approved by the Administrator in accordance with §121.407 of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Extended envelope training must include instructor-guided hands on experience of recovery from full stall and stick pusher activation, if equipped.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA has not mandated in-aircraft in-aircraft stall or Upset Prevention and Recovery Training. ICAO's Doc 10011, &lt;a href=&quot;http://www.icao.int/Meetings/LOCI/Pages/Upset-Prevention-and-Recovery-Training-Provisions.aspx&quot;&gt;Manual on Aeroplane Upset Prevention&#xA;and Recovery Training&lt;/a&gt; is pretty explicit:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On-aeroplane UPRT is not intended to be delivered while operating transport category aeroplanes or aeroplanes requiring two or more crew members; for those operations, UPRT should not be permitted to be conducted outside the confines of a suitable FSTD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a result of multiple stall related accidents ( including the &lt;a href=&quot;https://en.wikipedia.org/wiki/Colgan_Air_Flight_3407&quot;&gt;Colgan Air Flight 3407&lt;/a&gt;, a Bombardier Q-400, Turkish Airlines &lt;a href=&quot;https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951&quot;&gt;Flight 1951&lt;/a&gt;, a Boeing 737 and Air France &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot;&gt;Flight 447&lt;/a&gt;, an Airbus A330 ), both the industry and regulators have taken a number of steps taken to improve the stall and upset recovery training. For example, Airbus has changed the operational documentation of almost all its aircraft, including A320 (via FCOM volume 3 Temporary Revision number 323-1 and QRH Temporary Revision number 727-1)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ukfsc.co.uk/files/Safety%20Briefings%20_%20Presentations/Airbus%20Safety%20First%20Mag%20-January%202011.pdf&quot;&gt;The basic template&lt;/a&gt; of the stall recovery training is as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Immediately do the following at the first indication of stall (buffet, stick shaker, stick pusher, or aural or visual indication) during any flight phases except at lift off.&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Autopilot and autothrottle.............................. Disconnect&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;a) Nose down pitch control... Apply until out of stall&#xA;  (no longer have stall indications)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b) Nose down pitch trim................................... As needed&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Bank................................................................Wings Level&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Thrust................................................................As Needed&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Speed Brakes..........................................................Retract&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Bank................................................................Wings Level&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These have beeen incorporated in the FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1028646&quot;&gt;Advisory Circular 120-109A&lt;/a&gt; which changed the core principles taught to the pilots for recovering from stall. Still, the trainings are expected to be carried out in Flight Simulation Training Device only.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It is true that the pilots of Air Asia Flight 8501 were not given upset recovery training. However, this is according to the Flight Crew Training Manual and the philosophy that the aircraft's FBW system will prevent any such condition from occuring in the first place. From the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;32&quot;&gt;&#xA;  &lt;li&gt;The flight crew had not received the operator upset recovery training on Airbus A320 as it was not required according to the Airbus FCTM.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;37&quot;&gt;&#xA;  &lt;li&gt;The FCTM stated that the effectiveness of fly-by-wire architecture and the&#xA;  existence of control laws eliminate the need for upset recovery manoeuvres to be trained on protected Airbus.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-02T15:36:04.603" LastActivityDate="2015-12-02T15:36:04.603" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23351" PostTypeId="2" ParentId="23348" CreationDate="2015-12-02T14:47:43.067" Score="12" Body="&lt;p&gt;According to the &lt;a href=&quot;http://kemhubri.dephub.go.id/knkt/ntsc_aviation/baru/Final%20Report%20PK-AXC.pdf&quot;&gt;official investigation report&lt;/a&gt;, both the flight crew on this flight had received stall recovery training, but not upset recovery training, on the A320. The Flight Crew Training Manual for the A320 (issued by Airbus) did &lt;strong&gt;not&lt;/strong&gt; mandate upset recovery training. The operator's training manual (issued by Air Indonesia) &lt;strong&gt;did&lt;/strong&gt; mandate upset recovery training, but it was not delivered by the airline for pilots of the A320 because of Airbus's statement that it was unnecessary. Only upset prevention training was given. Both the below are from the linked report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The  approved  Operation  Training Manual covers  the  upset  recovery&#xA;  training  in Chapter 8. The  module  consisted  of ground and simulator training. The ground training provides the flight crew with the background, definition, cause of  aircraft upset, aerodynamic and  aircraft systems in &#xA;  relation with aircraft upset. Recovery methods consider various aircraft attitude and speed including post upset conditions. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The  upset recovery training  had  not  been  implemented on Airbus  A320 &#xA;  training, since it  is  not  required  according  to  the  Flight  Crew  Training  Manual  and  has not been mandated by the DGCA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and later&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Upset Recovery training was included in the aircraft operators training manual. The aircraft operator advised the KNKT that the flight crew had not been trained for the upset recovery training on Airbus A320, and this referred to FCTM Operational Philosophy: “The  effectiveness of fly-by-wire  architecture,  and  the  existence  of control  laws,  eliminates  the  need  for  upset  recovery  maneuvers  to  be  trained  on &#xA;  protected Airbus”. There was no evidence of DGCA findings for this incompliance of training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Upset aircraft&lt;/em&gt; is where the attitude or airspeed is greatly outside the normal flight envelope, such as might happen after a mid-air collision or loss of control, or (as in this case) prolonged wrong inputs when fly-by-wire is disengaged. A stall is not necessarily an upset aircraft condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The report also notes that the stall recovery training doesn't necessarily cover the developed stall, but rather recovering when the stall warning sounds before actually reaching the stall. The exercise is carried out from level flight by reducing airspeed and pitching up progressively to trigger the stall warning, and then pitching down to recover. (This is the same way stall recovery is taught to private pilots in smaller aircraft.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recovering from a developed stall where the aircraft's attitude is level but it is descending rapidly (stall at zero pitch) is &lt;strong&gt;not&lt;/strong&gt; mandatory training (p119), and this is the situation the flight crew were unable to recover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As there are too many crashes resulting from unrecovered stalls, the whole industry has worked together to produce better training programmes. One of the Safety Actions resulting from this crash is that Air Indonesia now gives upset recovery training to all its pilots, to comply with its own policy. In addition, the airliner manufacturers have produced a new training aid (applicable to most airplanes) for teaching upset recovery, and Airbus has already issued an Operations Training Transmission with instructions for carrying out suitable simulator training.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-12-02T14:47:43.067" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23352" PostTypeId="1" CreationDate="2015-12-02T17:41:34.930" Score="7" ViewCount="1593" Body="&lt;p&gt;What happens on the engine after ingesting volcanic ash? Is volcanic ash dangerous for the cockpit crew too? Despite the ground stations, is there any other way to identify volcanic ash while flying?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="52" LastEditDate="2015-12-02T17:54:37.960" LastActivityDate="2015-12-02T20:20:14.107" Title="Why is volcanic ash hazardous?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23353" PostTypeId="2" ParentId="23352" CreationDate="2015-12-02T17:55:25.913" Score="3" Body="&lt;p&gt;To start, because it's not just ash.  Larger particles can be carried in the plume as well.  In addition, the intense pressure and temperature of jet engines can reform the debris into larger particles and cause internal damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_travel_disruption_after_the_2010_Eyjafjallaj%C3%B6kull_eruption&quot; rel=&quot;nofollow&quot;&gt;Wikipedia on the 2010 Eyjafjallajökull eruption, which is a likely source of this question.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also hazard of external metal and glass damage due to high speed impact with these particles.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, visibility is obviously affected and lightning is a common occurrence in the plumes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's bad all around.&lt;/p&gt;&#xA;" OwnerUserId="11482" LastActivityDate="2015-12-02T17:55:25.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23354" PostTypeId="2" ParentId="23352" CreationDate="2015-12-02T19:02:42.260" Score="17" Body="&lt;p&gt;As mentioned in the comments &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_9&quot; rel=&quot;noreferrer&quot;&gt;BA flight 9 is a thorough example of why ash can be a huge issue&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Relevant points of that incident&lt;/h3&gt;&#xA;&lt;p&gt;One issue that ash creates is it cannot be seen on radar so it can be hard to track at night and must be reported by other means. This is deceiving as you would physically see what appears to be a cloud yet weather radar would not show anything.&lt;/p&gt;&#xA;&lt;p&gt;Inside the cabin, this depends on the granularity of the ash. Some of it will be filtered by the plane's air filters as any particulate matter would. However, ash can be extremely fine and what does make its way through the filters will present itself in a smoke like manner. This may cause alarm in the cabin and a false indication of a fire.&lt;/p&gt;&#xA;&lt;p&gt;When it comes to the exterior of the plane there are a few issues. The fine grains hitting the plane at that speed will act like sandpaper. The windshield may become scratched to the point you can't see through it (which is &lt;a href=&quot;http://www.cnn.com/2015/08/08/us/delta-emergency-landing-hail/&quot; rel=&quot;noreferrer&quot;&gt;not actually as big of an issue as some may assume&lt;/a&gt;). The paint will be effectively sanded off which in the short term is not a huge issue. More importantly it could affect your instrument inputs by clogging things like the static ports and pitot tube creating erroneous readings in the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;The engines were the main issue that arose on BA 9. In short the ash entered the engine, was melted and began to adhere to the blades of the jet. In turn this blocked the engine airflow and caused an engine stall. In the process BA 9 lost all four engines; however, when they began to descend the solidified ash cooled and broke off the engine allowing a restart.&lt;/p&gt;&#xA;&lt;p&gt;Air crash investigation covered the BA incident nicely in season 4. &lt;a href=&quot;https://www.youtube.com/watch?v=_D0sc6995Mc&quot; rel=&quot;noreferrer&quot;&gt;You can watch it here.&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;Other risks that BA 9 did not have&lt;/h3&gt;&#xA;&lt;p&gt;For a piston plane ash could potentially clog the air filter and starve the engine of air. Any super-fine ash that could get through the filter runs the risk of being ignited and causing detonation issue with in the engine. Likewise the sanding/grinding issue could have adverse effects on the propeller shape reducing its efficiency or even overall ability to act as an airfoil.&lt;/p&gt;&#xA;&lt;p&gt;There is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Volcanic_ash_and_aviation_safety&quot; rel=&quot;noreferrer&quot;&gt;nice wiki on it here&lt;/a&gt; and it appears that as of 1991 centers called &amp;quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Volcanic_Ash_Advisory_Center&quot; rel=&quot;noreferrer&quot;&gt;Volcanic Ash Advisory Center&lt;/a&gt;&amp;quot; have been set up to help track these very issues.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-02T20:20:14.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23356" PostTypeId="2" ParentId="23306" CreationDate="2015-12-02T20:14:02.787" Score="2" Body="&lt;p&gt;First of all, I just want to reiterate that you should absolutely follow the advice in &lt;a href=&quot;https://aviation.stackexchange.com/a/23310/755&quot;&gt;Ralph's answer&lt;/a&gt;. That is, learn to make good (wise, prudent) aeronautical decisions and talk to an actual instructor. Don't do risky things just to &quot;practice quick thinking.&quot; That's how you end up dead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, to actually answer the question regarding the lowest safe altitude, here's the regulation for Australia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The LSALT (Lowest Safe ALTitude) must be calculated using the following method:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;a. where the highest obstacle is more than 360FT above the height determined for terrain, the LSALT must be 1,000FT above the highest obstacle; or  &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;b. where the highest obstacle is less than 360FT above the terrain, or there is no charted obstacle, the LSALT must be 1,360FT above the elevation determined for terrain; except that  &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;c. where the elevation of the highest terrain or obstacle in the tolerance area is not above 500FT, the LSALT must not be less than 1,500FT.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://www.airservicesaustralia.com/aip/current/aip/general.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Publication Australia GEN 3.3 paragraph 4.5&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in summary, the lowest safe altitude is 1,000 ft. above the highest obstacle, except that it must be not less than 1,360 ft. above the highest terrain and not less than 1,500 ft. above sea level.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-02T20:14:02.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23357" PostTypeId="1" AcceptedAnswerId="23360" CreationDate="2015-12-02T23:31:14.033" Score="10" ViewCount="8786" Body="&lt;p&gt;I think negative lift is where high pressure forms on the top of the wing instead of the bottom. I know that Indy cars use negative lift and some sports cars do, but do any aircraft exist that use negative lift and why do they use negative lift?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="62" LastEditDate="2015-12-03T00:44:17.603" LastActivityDate="2015-12-03T12:38:21.860" Title="Do any aircraft out there use negative lift?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23358" PostTypeId="2" ParentId="23357" CreationDate="2015-12-02T23:44:45.157" Score="21" Body="&lt;p&gt;A lot of aircraft generate negative lift- not in the wings, but in the tail plane. This is used for stability. Consider a trimmed aircraft as shown below:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ma3cc.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ma3cc.gif&quot; alt=&quot;Trimmed aircraft&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from grc.nasa.gov&lt;/p&gt;&#xA;&lt;p&gt;On most aircraft, the center of gravity (through which weight acts) of the airplane is located near the center of pressure (through which lift acts) of the wing. If the center of presure of the wing is aft of the center of gravity, its lift produces a counter-clockwise rotation about the cg. A positive lift force from the tail produces a counter-clockwise rotation about the cg.&lt;/p&gt;&#xA;&lt;p&gt;To trim the aircraft (i.e. no rotation about c.g), it is necessary to balance the torques produced by the wing and the tail. But since both rotations are counter-clockwise, it is impossible to balance the two rotations to produce no rotation. However, if the tail lift is negative it then produces a clockwise rotation about the cg which can balance the wing rotation. For this reason, the tailplane is designed to produce a negative lift.&lt;/p&gt;&#xA;&lt;p&gt;Text from &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/trim.html&quot; rel=&quot;noreferrer&quot;&gt;Trimmed aircraft&lt;/a&gt;- slightly modified.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-02T23:44:45.157" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23359" PostTypeId="2" ParentId="23357" CreationDate="2015-12-02T23:44:52.037" Score="7" Body="&lt;p&gt;Yes. Most airplanes have the centre of mass forward of the centre of lift of the main wing(s). This would make the airplane &quot;tip over&quot; forwards, so the tailplane is an upside-down wing, and provides negative lift sufficient to balance the airplane. This is a conventional arrangement. On some, the &quot;car spoiler&quot; shape of the tailplane, with the flat side on top and the cambered side underneath, is very obvious.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-12-02T23:44:52.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23360" PostTypeId="2" ParentId="23357" CreationDate="2015-12-03T00:03:05.033" Score="4" Body="&lt;p&gt;&lt;strong&gt;Short Answer:&lt;/strong&gt; Yes&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Long Answer:&lt;/strong&gt; Well, partially....You see, lift is generated not only at the wings but also at the tail. The aircraft's tail has an elevator and a rudder (most single engine planes) by way of control structures. The pitching motion of the airplane is caused by altering the elevator's shape. The nose stays where it is (in the vertical plane) when the lift at the wings is balanced by that at the tail. However, when the lift at the tail increases the nose starts dropping. Similarly, when the lift at the tail decreases, the nose rises up. You could call the increased downward at the tail 'negative-lift'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope that answered your question. If you are patient enough, try reading &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2004.pdf&quot; rel=&quot;nofollow&quot;&gt;this chapter&lt;/a&gt; from the Pilot's Handbook of Aeronautical Knowledge. It is the same book I used for my pilot's license.&lt;/p&gt;&#xA;" OwnerUserId="12277" LastEditorUserId="3201" LastEditDate="2015-12-03T00:28:09.483" LastActivityDate="2015-12-03T00:28:09.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23363" PostTypeId="1" CreationDate="2015-12-03T03:34:37.827" Score="-3" ViewCount="503" Body="&lt;p&gt;ex. direct action, reconnaissance &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current military drones usually carry 4 hellfire missiles. If the military used a 747 drone the payload capacity could increase by a factor of 10.&lt;/p&gt;&#xA;" OwnerUserId="6998" LastEditorUserId="998" LastEditDate="2017-10-05T15:08:42.797" LastActivityDate="2017-10-05T15:08:42.797" Title="Is there any current knowledge of a 747 being used as a drone for military applications?" Tags="&lt;military&gt;&lt;unmanned-aerial-vehicle&gt;&lt;boeing-747&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-12-03T15:41:51.313" ContentLicense="CC BY-SA 3.0" />
  <row Id="23365" PostTypeId="1" AcceptedAnswerId="23369" CreationDate="2015-12-03T06:19:30.817" Score="2" ViewCount="2544" Body="&lt;p&gt;I have no knowledge about aviation or mechanics or something. Recently I started a computer game 'besiege', a kind of sandbox-like game with bunch of parts to make all kinds of machinery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I'm trying to make a single-propeller airplane. What I'm concerned about is that it might roll over. I made a simple helicopter once before, which rotated to the other direction of the way propeller(of course facing up) did when only one prop is attached. I know this is why another small prop is at the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, is my airplane going to stay in balance with single propeller? I considered putting one on another rotating to the opposite direction in the same speed too, but that isn't the way I am planning to. Thanks in advance.&lt;/p&gt;&#xA;" OwnerUserId="12516" LastEditorUserId="8960" LastEditDate="2015-12-03T14:12:45.390" LastActivityDate="2015-12-03T14:12:45.390" Title="How can an airplane fly with single propeller without rolling over?" Tags="&lt;aircraft-design&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ClosedDate="2015-12-03T12:30:01.927" ContentLicense="CC BY-SA 3.0" />
  <row Id="23366" PostTypeId="1" CreationDate="2015-12-03T07:43:53.570" Score="-2" ViewCount="1902" Body="&lt;p&gt;Could this be a feasible concept &lt;a href=&quot;http://aviationhumor.net/wp-content/uploads/2011/04/AirplaneJokes-0027.jpg&quot; rel=&quot;nofollow&quot;&gt;aircraft&lt;/a&gt; to replace the AC-130?&lt;/p&gt;&#xA;" OwnerUserId="6998" LastEditorUserId="4197" LastEditDate="2015-12-03T12:34:17.387" LastActivityDate="2015-12-03T12:34:17.387" Title="Is the Boeing AC-25A Banshee a real concept or a gimmick?" Tags="&lt;military&gt;&lt;boeing&gt;&lt;boeing-747&gt;&lt;experimental-aircraft&gt;&lt;us-air-force&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-03T18:12:14.390" ContentLicense="CC BY-SA 3.0" />
  <row Id="23367" PostTypeId="2" ParentId="23366" CreationDate="2015-12-03T08:01:43.517" Score="7" Body="&lt;p&gt;Well, the URL should give it away already ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AC-130 is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/why-are-propeller-engines-uncommon-on-commercial-aircraft/1088#1088&quot;&gt;turboprop aircraft&lt;/a&gt; with relatively low wing loading. It can be operated from (almost) unprepared airstrips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now compare it to the 747-400: Higher minimum speed means more distance to the taget, higher &lt;a href=&quot;https://aviation.stackexchange.com/questions/7485/can-jet-airplanes-operate-on-rough-airfields/7496?s=2%7C0.2471#7496&quot;&gt;tire pressure&lt;/a&gt; means operation from established airbases with a long runway. Just look at the T-tail: Such a change would necessitate a complete redesign of the rear fuselage and the vertical tail. With the changes photoshopped into the picture the &quot;AC-25&quot; would be 80% new and could use only a few parts from the 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an incomplete list of what needs to be changed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Lifting the wing up to a high wing position would need less dihedral (&lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/why-does-an-225-have-anhedral-wings-though-it-is-a-cargo-aircraft?s=2%7C0.9350&quot;&gt;or even some anhedral&lt;/a&gt;, to be precise), so the wing needs major modifications&lt;/li&gt;&#xA;&lt;li&gt;The landing gear would need a complete redesign. Currently, some parts retract into the wing, which is no longer there. The pods at the side of the fuselage are too small to hold the current gear.&lt;/li&gt;&#xA;&lt;li&gt;The mid fuselage section is a new design, too. Moving the wing up means a complete redesign of the bulkheads and wing attachment points. Also, fuel lines and cables need to be re-routed. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-03T08:01:43.517" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23368" PostTypeId="2" ParentId="23365" CreationDate="2015-12-03T08:05:37.630" Score="0" Body="&lt;p&gt;An aircraft has control surfaces for controlling its attitude: &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevator_(aeronautics)&quot; rel=&quot;nofollow&quot;&gt;elevators&lt;/a&gt; for pitch, &lt;a href=&quot;https://en.wikipedia.org/wiki/Aileron&quot; rel=&quot;nofollow&quot;&gt;ailerons&lt;/a&gt; for roll and &lt;a href=&quot;https://en.wikipedia.org/wiki/Rudder#Aircraft_rudders&quot; rel=&quot;nofollow&quot;&gt;rudder&lt;/a&gt; for yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At flying speed, the ailerons can provide much more torque than the propeller and the rudder can provide more torque than the &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow&quot;&gt;p-factor&lt;/a&gt; and the effect of the rotating slipstream, so the aircraft simply flies straight with ailerons and rudder slightly deflected, with the amount of deflection depending on the engine power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground, wheel steering or asymmetrical braking is used to compensate the yaw below the speed at which rudder becomes effective and roll stability is ensured simply by the main gear track width.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-12-03T08:05:37.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23369" PostTypeId="2" ParentId="23365" CreationDate="2015-12-03T08:06:26.807" Score="4" Body="&lt;p&gt;When it is slow, the two or three wheels should keep it from flipping over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once it is fast enough to fly, the wing will provide what we engineers call roll damping: Any tendency to roll† will cause an opposing moment which will stop the motion quickly. The rest is done by a differential deflection of the ailerons, so the wing creates an equal and opposite rolling moment to that of the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is roll damping: Once the wing starts to roll, one side will go up while the other goes down. This will cause a change in local angle of attack and, consequently, local lift. The down-moving wing will see a higher angle of attack and a local lift increase, and the opposite happens on the other side. Total lift will remain unchanged, but now the change in the spanwise lift distribution will lift the down-moving wing back up and vice versa. The movement stops before it could pick up any speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With powerful engines, engine torque is a real problem and needs to be canceled with a few tricks:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Camber on the vertical tail: The vertical tail will create a side force and rolling moment which depends on the speed of the air flowing over the vertical. This helps to make the correction depend on the power setting of the engine. Just make sure that the vertical is in the slipstream of the propeller.&lt;/li&gt;&#xA;&lt;li&gt;With &lt;a href=&quot;https://aviation.stackexchange.com/questions/14820/what-is-the-purpose-of-having-contra-rotating-props-on-an-aircraft&quot;&gt;contra-rotating&lt;/a&gt; propellers you can cancel the rolling moment of each propeller with that of the other. This needs a more complex gearbox, however.&lt;/li&gt;&#xA;&lt;li&gt;In operation, apply power changes only slowly. With its narrow undercarriage, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_109&quot; rel=&quot;nofollow noreferrer&quot;&gt;Me-109&lt;/a&gt; would become uncontrollable if the pilot went from idle to full power on the ground too quickly.&lt;/li&gt;&#xA;&lt;li&gt;Watch the &lt;a href=&quot;https://aviation.stackexchange.com/questions/700/uniform-turbine-rotation-direction/7425#7425&quot;&gt;gyro forces of a spinning propeller&lt;/a&gt;: In &lt;a href=&quot;https://aviation.stackexchange.com/questions/8550/why-tail-wheel-rather-than-tricycle/8553#8553&quot;&gt;taildraggers&lt;/a&gt;, the aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/7886/how-difficult-is-it-to-avoid-ground-loop-in-practice&quot;&gt;will yaw due to gyro forces&lt;/a&gt; once the tail is lifted during the ground run or the pitch attitude is changed in flight. Also, yawing (rotation around the vertical axis) will create a pitch moment (which acts around the spanwise axis).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;† Roll: Movement around the longitudinal axis.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2015-12-03T08:32:37.057" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23371" PostTypeId="2" ParentId="23363" CreationDate="2015-12-03T10:47:47.830" Score="8" Body="&lt;p&gt;There are no known 747s being used as drones, nor is there any public program to do so. Sure a weaponized 747 could carry a lot of missiles. Actually, there was a proposal to convert 747 into a missile carrier, called the Cruise Missile Carrier Aircraft or CMCA (it was manned though). And the factor of 10 is pretty conservative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CMCA was expected to carry more than 70 Air launched cruise missiles, specifically the &lt;a href=&quot;https://en.wikipedia.org/wiki/AGM-86_ALCM&quot; rel=&quot;noreferrer&quot;&gt;AGM-86 ALCM&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GbcgA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GbcgA.jpg&quot; alt=&quot;CMCA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from foxtrotalpha.jalopnik.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea was to modify the nose loading 747-200C, with nine rotary launchers mounted on tracks inside of the stripped-out cabin. Each rotary launcher would hold eight missiles, and they could be slid back into a launching position at the rear right side of the aircraft through an overhead handling system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A bay door on the right side of the 747's tail cone would open and an ejector system would launch the missiles either singly or in a salvo. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea was proposed when the B-1 was canceled and died when it was revived.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-03T10:55:54.423" LastActivityDate="2015-12-03T10:55:54.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23372" PostTypeId="1" AcceptedAnswerId="23374" CreationDate="2015-12-03T12:24:51.463" Score="20" ViewCount="6189" Body="&lt;p&gt;I noticed that armrests on all the flight's I've taken recently can't be lifted on aisle and window seats (the edges of a row).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last time I flew, I got lucky: I was alone on my row and as such I was able to lay down to sleep. However, it was hard to make myself comfortable as that armrest was pressing on my spine when I tried laying down with my back to the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it would be much easier to get out of my aisle seat if I could lift the armrest. I'm a pretty tall guy, so I always feel like a contortionist trying to get out of my seat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the problem with letting people raise the armrest on window and aisle seats? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing it's some sort of safety issue, because the mechanism seems to be the exact same one as the other seats, just with an extra locking mechanism added.&lt;/p&gt;&#xA;" OwnerUserId="12519" LastActivityDate="2016-02-02T22:26:19.703" Title="Why can't armrests be raised on window and aisle seats?" Tags="&lt;passenger&gt;&lt;seats&gt;&lt;comfort&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23373" PostTypeId="2" ParentId="23357" CreationDate="2015-12-03T12:38:21.860" Score="15" Body="&lt;p&gt;Yes  .  .  .  .  .  .  .  .  .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T4NjF.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T4NjF.jpg&quot; alt=&quot;flying upside down&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1717" LastActivityDate="2015-12-03T12:38:21.860" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23374" PostTypeId="2" ParentId="23372" CreationDate="2015-12-03T12:54:19.413" Score="15" Body="&lt;p&gt;Apparently, &lt;a href=&quot;http://www.milevalue.com/how-did-i-just-learn-this-awesome-trick-to-get-more-space-in-coach/&quot;&gt;it can be done&lt;/a&gt;, atleast in some aircraft; even in those cases, the armrests are locked, unless one knows the location of the release button.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why, it seems that there is a possibility that the upright armrests can be an obstacle (for people in the next seat row) and FAA expects the cabin crew to ensure that the armrests are in forward condition prior to takeoff/landing. According to FAA Volume 3, Chapter 33, Section 3 &lt;a href=&quot;http://fsims.faa.gov/WDocs/8900.1/V03%20Tech%20Admin/Chapter%2033/03_033_003.htm&quot;&gt;Instrument and Equipment Requirements&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Inspection of the Hardman Model 9500 and other passenger seats installed on several aircraft, disclosed that the armrest in the upright or stowed position can protrude approximately 45 degrees aft the seat back. In the event of an emergency evacuation, protruding armrests could present an obstacle between seat passageways, obstructing emergency exit access. Air Carriers should emphasize to F/As that prior to takeoff and landing they verify that the armrests are in the normal forward/down position in order to ensure that they do not obstruct the passageway between the row of seats leading from the aisle to the emergency exit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As this is a problem in aisle seats (armrests in middle seats cannot go back usually), they have to be fixed forward or atleast locked in position. This is the reason for them to be locked in case of aisle seats. As for window seats, the sets are usually made in a row and you don't really know if the seat will end up in window or aisle i.e. whether the row will get fixed on left or right (or middle, in widebodies). Net result is that both the ends of the row are fixed just to be sure. In other words, the windows armrest is a collateral damage.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-03T13:04:04.393" LastActivityDate="2015-12-03T13:04:04.393" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23375" PostTypeId="1" CreationDate="2015-12-03T14:32:59.620" Score="9" ViewCount="4969" Body="&lt;p&gt;I'd like to know how you choose the location of the engines under the wings, in the case of a 4-engines aircraft with low wings (and therefore with engines under the wings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning the longitudinal location, what are the constraints? Nacelles are usually in front of the wing, but why? I know there is a security constraint, especially with high bypass ratio engines, but is that all?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concerning the lateral position, you want to reduce the bending moment of the wings, and therefore have your engines close to the wing tips during flight. But one could also say you want the engines close to the CG to reduce bending moments on the ground... Which constraint is dominant? And why can't we have to engines close to each other? (far enough to avoid flow interactions)&lt;/p&gt;&#xA;" OwnerUserId="12521" LastEditorUserId="14897" LastEditDate="2020-01-27T19:23:54.640" LastActivityDate="2020-01-27T19:23:54.640" Title="How do you choose engine placement for under wings engines?" Tags="&lt;aircraft-design&gt;&lt;engine-placement&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23376" PostTypeId="2" ParentId="23375" CreationDate="2015-12-03T14:58:08.133" Score="4" Body="&lt;p&gt;Any design decision is an optimization problem which involve a number of diverse factors. There are multiple parameters to consider while determining the location of engines in the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longitudinal location&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Clearance- In case of high bypass turbofans, farther the engine is out in the wing, greater is the clearance in ground (and require less landing gear length). In some cases where high bypass engines were retrofitted on aircraft, the engine inlet shapes had to be non-circular to get the required clearance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/diOvx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/diOvx.jpg&quot; alt=&quot;Inlet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CFM56 engine on Boeing 737, Image from asec.ir&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Interference- The engine mounting (pylon and nacelle) interferes with the airflow over the wing, which affects the longitudinal location.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Safety- Any uncontained failure of the engine disks should not damage the primary structure of the wing, which influences the longitudinal location of the engine. Also, any engine (part) failure should not affect the wing leading edge devices. For this reason, the engines are mounted well in front of the wings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xt0No.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xt0No.gif&quot; alt=&quot;Forward mounting&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical engine mounting, from adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The longitudinal location is also affected by the requirement of operating thrust reversers, which basically deploys a section of the nacelle aft and out.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0HCCZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0HCCZ.jpg&quot; alt=&quot;787 Thrust reversers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 787 thrust reverser operation. Image from www.pbase.com&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The location of the engine center of gravity forward of the wing produces a torsional moment, which has the effect of increasing wing stiffness.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Lateral Location:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Stability- Closer the engines are to the fuselage, lesser the yawing moment in case of an engine failure.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Control surfaces- Usually, control surfaces i.e. flaps are not present aft of the engine as the high temperature flow requires special materials. This leads to reduced Cl_max. The following figure clearly shows the absence of high lift surfaces aft of the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/560B7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/560B7.jpg&quot; alt=&quot;Engine aft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Undercarriage.b747.arp.jpg#/media/File:Undercarriage.b747.arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Undercarriage.b747.arp&lt;/a&gt;&quot; by Arpingstone - Photographed by Adrian Pingstone in August 2002 and released to the public domain.. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Drag- In this case, engines buried in the wing root is the best location. However, it is rarely used due to various reasons- difficult engine maintenance, wing redesign required if a new engine is to be used, elimination of inboard flap, etc. The location of the engine also affects the interference drag (with the fuselage).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fCUTN.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fCUTN.gif&quot; alt=&quot;Interference&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Effect of large engine on interference drag, image from adg.stanford.edu&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing loads- The location of the engine in the wing helps to relieve the wing bending moment in flight (as for reducing the bending moment in ground, compare the flight and ground loads).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The location of engine is determined after considering all these (and many other) factors.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-03T16:05:30.840" LastActivityDate="2015-12-03T16:05:30.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23379" PostTypeId="1" AcceptedAnswerId="23467" CreationDate="2015-12-03T22:46:05.470" Score="16" ViewCount="1850" Body="&lt;p&gt;I found the following picture on the Blue Angels Facebook page:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/A0NCV.jpg&quot; alt=&quot;US Navy Blue Angels F/A-18 cockpit&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of the lights over the pilot's panel? (The two on the top are green) &lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="1467" LastEditDate="2017-12-14T08:45:28.043" LastActivityDate="2018-11-15T01:41:37.567" Title="What are these lights above the panel in a Blue Angels cockpit?" Tags="&lt;flight-instruments&gt;&lt;cockpit&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23380" PostTypeId="1" AcceptedAnswerId="23384" CreationDate="2015-12-03T22:47:52.247" Score="8" ViewCount="988" Body="&lt;p&gt;I'm doing some work on streamlining my process for designing new aircraft, and in the process creating/looking for rules of thumb and shortcuts one can use when designing. I'm currently in the process of creating a way of quickly estimating L/D of an aircraft in conceptual design stage. I'm looking for something that doesn't involve a ton of CFD or windtunnel time, and can be incorporated into a spreadsheet. It needs to be +/- 10% of the actual L/D achieved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been able to figure out lift and drag of individual components pretty easily. However, I'm having trouble with figuring a quick way of estimating interference drag. What shortcuts do experienced designers use for estimating interference drag quickly?&lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2015-12-04T01:12:43.547" Title="How can one quickly estimate interference drag for a configuration?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23381" PostTypeId="1" AcceptedAnswerId="23383" CreationDate="2015-12-04T00:36:43.910" Score="15" ViewCount="3878" Body="&lt;p&gt;If a military pilot is captured by an enemy, how can he indicate that he has run out of ammunition to engage in combat or is not in a position to retaliate? Does he use lights, radio, and/or flares?&lt;/p&gt;&#xA;" OwnerUserId="8259" LastEditorUserId="2143" LastEditDate="2015-12-05T17:04:54.987" LastActivityDate="2019-06-11T15:25:01.313" Title="How can a military combat pilot indicate surrender?" Tags="&lt;military&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23382" PostTypeId="2" ParentId="23375" CreationDate="2015-12-04T00:40:47.340" Score="8" Body="&lt;p&gt;After having read aeroalias' picture collection, I feel an urge to chime in.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longitudinal position&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The main reason to place them ahead of the wing is flutter suppression. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5154/why-can-not-two-modes-coincide-perfectly-for-some-cases-in-flutter-phenomena/5158?s=3%7C0.0936#5158&quot;&gt;Flutter&lt;/a&gt; is an oscillation caused by the interaction of elastic and aerodynamic forces. In case of the wing, it is an up-down bending motion. Since air takes its time to flow over the wing, at a certain airspeed the air pressure change on the wing is so much out of phase with the motion that it amplifies the elastic motion of the wing. By placing the center of gravity of the aircraft part ahead of its &lt;a href=&quot;http://www.mindat.org/glossary/elastic_axis&quot; rel=&quot;noreferrer&quot;&gt;elastic axis&lt;/a&gt;, flutter can be suppressed. This is true of flaps (where a mass balance is added ahead of the hinge line) as of full wings (where engines take the part of the mass balance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine the wing bending up, and now add the inertial forces of an engine connected to this wing and also moving up. If it is placed ahead of the elastic axis, it will induce a torsion moment into the wing, such that the local angle of attack is reduced, which in turn will reduce lift and the forces which cause the wing to bend upwards. The same happens in opposite direction when the wing bends downwards. Since the biggest thickness of the wing is in its forward section (which shifts the elastic axis forward) and the heavy flap mechanism is in its rear section (which shifts the local center of gravity back), a wing without an engine mounted forward of it needs a much heavier structure or less heavy, but otherwise unproductive, balance weights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placing the engine ahead of the wing brings some more benefits:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airflow at the intake is less influenced by the pressure field of the wing, so the variation in local flow direction is smaller, resulting in a better-performing intake.&lt;/li&gt;&#xA;&lt;li&gt;An &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbine_engine_failure#Contained_and_uncontained_failures&quot; rel=&quot;noreferrer&quot;&gt;uncontained turbine failure&lt;/a&gt; is less likely to damage the wing.&lt;/li&gt;&#xA;&lt;li&gt;The engine can be mounted &lt;a href=&quot;https://aviation.stackexchange.com/questions/5160/why-dont-all-aircraft-use-need-nacelle-chines/5162#5162&quot;&gt;higher relative to the wing&lt;/a&gt;, such that the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12109/why-do-we-use-pylons-to-mount-engine-on-jet-airliners/12118#12118&quot;&gt;landing gear can be shortened&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why engines are not placed on top of the wing is discussed in &lt;a href=&quot;https://aviation.stackexchange.com/questions/9680/why-not-mount-airliner-jet-engines-above-the-wings/9688?s=27%7C0.0854#9688&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Lateral position&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In two- and three-engined jets you put them at the wing station where the inner wing ends. The main reasons are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is a major rib anyway to support the wing's skin, so the structure for attaching an engine is easier to add.&lt;/li&gt;&#xA;&lt;li&gt;There is a gap between inner and outer flaps (at least in Boeing designs), so the &lt;a href=&quot;https://aviation.stackexchange.com/questions/20969/what-are-these-parts-on-the-wing-of-a-boeing-737/20980#20980&quot;&gt;engine blast will not hit the flaps&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;They are still relatively close to the center of the airplane to not require an excessively large vertical tail to cancel the yawing moment in single-engine flight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/haEx0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/haEx0.jpg&quot; alt=&quot;Boeing 737 bottom view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737 bottom view (picture by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;noreferrer&quot;&gt;Adrian Pingstone&lt;/a&gt;). The inner wing section has an unswept trailing edge while the outer wing has less taper and a swept trailing edge. The engines are exactly where both meet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft like the DC-8 had their inner engines at the wing rib which supported the inner flap tracks of the outer Fowler flap, because they had no gap between inner and outer flaps. On the DC-10, Douglas placed the wing engines at the break between inner and outer wing, however.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In four-engined jets the inner engines are placed like those on two-engined jets, while the outer engines are placed at the end (or slightly outside) of the outer Fowler flaps, about midway between the inner engine and the wing tip. Note that again a rib is needed where the aileron cutout starts - this rib doubles as the engine mount. There the engines can contribute a lot to bending relief, and since a single engine contributes only 25% of the total thrust, the yawing moment of the outer engine in the engine-out case is roughly equal to that of a single engine of a two-engined jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cP2OE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cP2OE.jpg&quot; alt=&quot;Airbus A340 bottom view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A340 bottom view (picture by &lt;a href=&quot;https://commons.wikimedia.org/wiki/User:Arpingstone&quot; rel=&quot;noreferrer&quot;&gt;Adrian Pingstone&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why it is better to separate the engines and spread them out over the wing instead of collecting them in a single nacelle is explained in &lt;a href=&quot;https://aviation.stackexchange.com/questions/19208/why-are-the-boeing-747-8-engines-on-the-wings-spread-apart/19211?s=3|0.0658#19211&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, the engine location is dictated by other requirements. On the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-70&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-70&lt;/a&gt; the inner engines need to be far enough out to allow to drop paratroopers from the front door, for example.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-12-04T17:56:59.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23383" PostTypeId="2" ParentId="23381" CreationDate="2015-12-04T01:11:33.593" Score="16" Body="&lt;p&gt;There is no universally accepted means of surrendering an aircraft. According to &lt;a href=&quot;http://www.ihlresearch.org/amw/manual/section-s-surrender/s-specifics-of-air-or-missile-operations/rule-128&quot;&gt;Humanitarian Policy and Conflict Research at Harvard University&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircrews of a military aircraft wishing to surrender ought to do everything feasible to express clearly their intention to do so. In particular, they ought to communicate their intention on a common radio channel such as a distress frequency. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They can do other things like rocking the wings, jettisoning the weapons, flashing navigational lights etc. However, none of these are universally accepted or even have a clear meaning in the heat of combat. So the best course of action will be to bail out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot is &lt;em&gt;captured&lt;/em&gt; by an enemy, there would be no need to surrender.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-04T01:11:33.593" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23384" PostTypeId="2" ParentId="23380" CreationDate="2015-12-04T01:12:43.547" Score="5" Body="&lt;p&gt;Use Sighard Hoerner's &lt;a href=&quot;https://www.scribd.com/doc/117103507/Hoerner-Fluid-Dynamic-Drag&quot; rel=&quot;noreferrer&quot;&gt;Fluid Dynamic Drag&lt;/a&gt;. It lists tons of wind tunnel and flight test data for a wide variety of configurations and flight regimes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interference drag has several sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flow separation due to the coincidence of the pressure rises of two bodies. Each of them by itself would show attached flow, but in the vicinity of a similar body with its own pressure rise, the flow separates. This is most pronounced at low speed.&lt;/li&gt;&#xA;&lt;li&gt;Addition of the accelerated flow of two bodies in transsonic flight. While each of the single bodies has no supersonic pocket around it, both in combination will cause a local supersonic area with a subsequent shock.&lt;/li&gt;&#xA;&lt;li&gt;Disturbance in the spanwise lift distribution, such as wings interrupted by the fuselage or engine nacelles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Look for areas where one of these conditions is fulfilled, and then try to find a similar case in Horner's book to estimate its severity. Note that all interference drag varies with speed and angle of attack. Doing so carefully will bring you within 10% of the real drag, but needs some experience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, drag estimation is like bookkeeping. You need to carefully add each component and make sure to avoid double-counting or mixing up reference areas. Sorry, but if you want a good result there are no shortcuts.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-04T01:12:43.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23385" PostTypeId="1" CreationDate="2015-12-04T07:01:10.350" Score="7" ViewCount="867" Body="&lt;p&gt;I'm calculating the lift of a Cessna 172 and I don't understand the numbers given for weight. The maximum landing weight is 2550 pounds which is nearly 1134kg. But does that mean 1134 Newtons (weight) or 1134 kilograms (mass)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since &lt;em&gt;weight = mass x gravity&lt;/em&gt;, I think the weight of the C172 is in Newtons even though it's written using a unit of mass. Am I correct?&lt;/p&gt;&#xA;" OwnerUserId="12529" LastEditorUserId="62" LastEditDate="2015-12-04T12:55:00.090" LastActivityDate="2017-12-15T04:26:18.670" Title="Is an aircraft's maximum landing weight really weight, or is it mass?" Tags="&lt;lift&gt;&lt;cessna-172&gt;&lt;weight&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23386" PostTypeId="1" CreationDate="2015-12-04T11:29:07.933" Score="22" ViewCount="13664" Body="&lt;p&gt;Why is it that control sticks for the captains on Airbus are placed on the left? Wouldn't it be uncomfortable considering that most of the people, and by consequence pilots, are right handed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my opinion this would make flying more difficult as a right handed person would have less sensitivity on his left hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5hdv9.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5hdv9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://www.airbus.com/aircraft/passenger-aircraft/a320-family/a320neo.html&quot; rel=&quot;noreferrer&quot;&gt;airbus.com&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="14897" LastEditDate="2019-02-26T21:03:44.567" LastActivityDate="2020-09-28T14:57:51.420" Title="Why are Airbus captain control sticks placed on the left when most people are right-handed?" Tags="&lt;flight-controls&gt;&lt;cockpit&gt;&lt;airbus&gt;&lt;human-factors&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="23387" PostTypeId="2" ParentId="23386" CreationDate="2015-12-04T12:41:14.207" Score="25" Body="&lt;p&gt;The Airbus is actually configured the same as the vast majority of other General Aviation and Civil Aviation aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key factor is that the throttle is almost always the middle - meaning that  as pilots get used to sitting in the left seat early on in their training, they become accustomed to using the throttle with their right hand and the control column in the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's something of a misconception to think that pilots spend much, if any, time with both hands on the control column. The right hand is almost always somewhere else – configuring radios, squawks, navigation equipment, throttles and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Watch this video of a Citation Jet – particularly during takeoff and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/kXqg8lfj-Zg?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot on the left is using his control column in exactly the same way as he would on an Airbus. You'll note that when his right hand &lt;em&gt;is&lt;/em&gt; on the control column, it doesn't become dominant – it's just a resting position.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastEditorUserId="11671" LastEditDate="2020-04-22T20:40:17.177" LastActivityDate="2020-04-22T20:40:17.177" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23388" PostTypeId="1" AcceptedAnswerId="23391" CreationDate="2015-12-04T12:45:49.580" Score="2" ViewCount="19922" Body="&lt;p&gt;Looking at pictures from cockpits of various aircrafts, we can see two types of control-inputs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sidestick:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ISoOh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ISoOh.jpg&quot; alt=&quot;Sidestick&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the yoke:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ud7Nc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ud7Nc.png&quot; alt=&quot;yoke&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages / disadvantages of both? When is a yoke over a sidestick used? Can the yoke / sidestick do something that isn't possible with the other option?&lt;/p&gt;&#xA;" OwnerUserId="9544" LastActivityDate="2015-12-04T13:40:09.053" Title="Sidestick vs. Yoke" Tags="&lt;flight-controls&gt;&lt;cockpit&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ClosedDate="2015-12-04T14:21:26.603" ContentLicense="CC BY-SA 3.0" />
  <row Id="23389" PostTypeId="2" ParentId="23386" CreationDate="2015-12-04T12:46:45.677" Score="17" Body="&lt;p&gt;First, even if the aircraft is controlled using a yoke, the pilot is still controlling using his left hand (left hand on column, right hand on throttles/PCL). This is not much different and almost all pilots switch from controlling using their right hand to left hand pretty easily (they'll usually do this while training itself as they switch seats). The basic concept is same as say, a Boeing 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2L5t0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2L5t0.jpg&quot; alt=&quot;737 Cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737 cockpit, from gearthhacks.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic control layout in airliners is that the pilot/copilot controls the yoke/sidestick with one hand and throttles/TCL (and flaps etc.) with the other hand. Having dissimilar layout for pilot/copilot has some advantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the minimum, the throttles can be placed in the center. If the pilot's sidestick is to (his) right, then the throttles have to be placed in the left, resulting in duplication. This can be seen in the B1 Lancer, where the pilot's throttles are in the left (though the aircraft has a centre stick).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dKzR9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dKzR9.jpg&quot; alt=&quot;B1 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from left wingsovereurope.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this may be possible if only the throttles were to be duplicated, it is very difficult to do so with the whole center console.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, having the sidestick to the left side serves as a good hand(wrist) rest.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-04T12:46:45.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23390" PostTypeId="1" CreationDate="2015-12-04T13:07:04.943" Score="0" ViewCount="58" Body="&lt;p&gt;If its submerged in water, will water rush inside the cabin? For instances, if its standing in a flooded airport or landed on the water gently.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2015-12-04T13:07:04.943" Title="Are commercial aircraft water tight by design?" Tags="&lt;cabin-design&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-12-04T14:15:48.833" ContentLicense="CC BY-SA 3.0" />
  <row Id="23391" PostTypeId="2" ParentId="23388" CreationDate="2015-12-04T13:40:09.053" Score="2" Body="&lt;p&gt;Initially, aircrafts with side-by-side seating configuration of pilots used the yokes overwhelmingly. The following figure shows the cockpit of Douglas DC-3.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t8nGq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t8nGq.jpg&quot; alt=&quot;DC-3 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from www.wingsovereurope.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First commercial aircrafts, the WWII bombers and initial jet transports used them. The first Airbus aircraft, A300 had them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6fHOr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6fHOr.jpg&quot; alt=&quot;A300 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A300 cockpit; image from airlinerworld.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The yokes have some characteristics like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They have less sensitivity (compared to sidesticks) and a larger range of motion.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They take up a lot of space and can obscure the instruments in front. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They can be used with either hand.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They can be used pretty much in all types of aircraft- from GA aircraft with conventional controls like Cessna 172 to FBW like the Boeing 787.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One useful thing with yoke is that the pilot and copilot yokes can be mechanically coupled, which is near impossible in a sidestick.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The yoke also provides the other pilot with a visual indication of the control input given.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The sidestick was first introduced in the Airbus 320 along with the FBW. It is doubtful of it would've come into being in aircraft with conventional controls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ObD4P.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ObD4P.jpg&quot; alt=&quot;A320 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sidesticks differ from the yokes in a number of ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The sidesticks are much more sensitive, but have lesser range of travel. They also lend themselves to rapid movements.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Spacewise, they offer significant advantages as they clear up a lot of room in front of the pilot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In two person cockpits, the sidesticks provide little or no visual indication as to the control input applied; for example, in Airbus aircraft, the sticks move independently and the computer interprets the actions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They can only be operated with a single hand.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They usually require a FBW system for operation. For small GA aircraft, they are rarely, if ever used.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-04T13:40:09.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23392" PostTypeId="1" AcceptedAnswerId="23394" CreationDate="2015-12-04T13:43:06.173" Score="8" ViewCount="6947" Body="&lt;p&gt;I have noticed that on airliners the ailerons have different angles if deflecting upwards than deflecting downwards. When deflected at the maximum angle maximum angle downwards is lower than when deflected upwards. I suppose that this is due to the fact that when the wing has to be deflected upwards and consequently the aileron moves downwards, the force required is lower as there is already lift being produced by the wing whereas the opposite would happen when deflecting the wing downwards and more power is required. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this assumption true or are there any other technical reasons behind this deflection angle difference?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-12-04T23:00:58.873" LastActivityDate="2019-06-06T12:33:19.350" Title="Why is there a difference between aileron upwards and downwards deflection angles?" Tags="&lt;wing&gt;&lt;ailerons&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23393" PostTypeId="1" AcceptedAnswerId="23397" CreationDate="2015-12-04T13:56:10.263" Score="3" ViewCount="607" Body="&lt;p&gt;Why are the engine pods on the Embraer 190 thicker, related to the overall diameter of the engine, than most of the other pods on other jets? Wouldn't this design add more drag and reduce efficiency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pictures added for reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Embraer 190:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ySo8y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ySo8y.jpg&quot; alt=&quot;Embraer 190&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1PvSk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1PvSk.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A330&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MEYQ6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MEYQ6.jpg&quot; alt=&quot;Airbus A330&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-12-04T22:49:49.017" LastActivityDate="2015-12-04T22:49:49.017" Title="Why are some engine nacelles thicker than others?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23394" PostTypeId="2" ParentId="23392" CreationDate="2015-12-04T14:04:40.133" Score="8" Body="&lt;p&gt;You're correct that the ailerons are deflected differently when they are deflected up or down. This is done in order to counter the adverse yaw effect which occurs when ailerons are deployed. Consider the situation when the ailerons are deployed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aC0U2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aC0U2.jpg&quot; alt=&quot;Aileron deflection&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from aerospaceweb.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One aileron is deflected downward while the other is deflected upward. One the side with the downward-deflected aileron, lift increases as the deflection effectively increases the camber of that portion of the wing. The opposite happens in the other side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the drag is also affected by aileron deflection- both induced and profile drags. For same deflection, the profile drag increase is same in both the wings. However, the induced drag on both sides are not equal, with a larger amount the wing with the down aileron (as the lift is more and induced drag is proportional to the square of lift).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way of overcoming this is to deflect the ailerons differentially, i.e. deflect the down aileron by a lesser amount than the up aileron. The following table shows the aileron deflection in a number of aircraft, which shows the differential aileron deflection ($\delta_{A}$ is the aileron deflection, in degrees).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hWo2H.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hWo2H.png&quot; alt=&quot;Aileron deflection&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Table from &lt;em&gt;Aircraft Design: A Systems Engineering Approach&lt;/em&gt; by Mohammad Sadraey&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This adverse yaw can also be prevented by the use of,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Frise ailerons&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Use of spoilers (in the wing up aileron)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cross coupled controls (rudder and ailerons).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There is another reason to use a differential aileron- to prevent tip stall at high angles of attack (stall speeds). The rolling couple on the aircraft is always the difference in lift between the two wings. At or near stalling speeds, it is better to reduce the lift in up-going aileron than increase it in down moving one and risk stalling it.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-04T14:25:49.650" LastActivityDate="2015-12-04T14:25:49.650" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23395" PostTypeId="2" ParentId="23385" CreationDate="2015-12-04T15:32:32.853" Score="8" Body="&lt;p&gt;The maximum landing weight given here is actually the &lt;em&gt;mass&lt;/em&gt;, not weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the various 'weights' given for aircraft are masses, not weights. i.e. they are in kilograms, not Newtons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is simply an extension of our everyday usage. As @mins pointed out, if someone asks your weight, you tell your mass (70 kg or whatever), not the weight itself (~686N).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-04T15:32:32.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23396" PostTypeId="2" ParentId="23385" CreationDate="2015-12-04T15:46:31.447" Score="8" Body="&lt;p&gt;On Planet Earth, 1kg of mass exerts 9.81 Newtons of force (weight).&#xA;Because this is true anywhere on planet Earth to within a tiny fraction of a percent, we use kg as a convenient measure of weight, even though pedantically it is a measure of mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are thinking of landing your C-172 on the Moon, Mars, or some other locale where G is different from 9.81 ms-2, then you'll have to convert kg to Newtons of weight.   Otherwise, you should consider kg a unit of both mass and weight.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-12-04T17:59:01.337" LastActivityDate="2015-12-04T17:59:01.337" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23397" PostTypeId="2" ParentId="23393" CreationDate="2015-12-04T15:52:26.050" Score="3" Body="&lt;p&gt;The nacelle contains a lot of equipment for controlling the engine. While this will certainly scale with the size of the engine, there is also some amount of minimum space needed for the components. The volume also increases faster than the surface area, so there is more room to spread things out. You will notice that the general trend in your pictures is relatively thinner nacelles as the engine diameter goes up:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E190 - CF34 - 57 in&lt;br&gt;&#xA;B737 - CFM56 - 61 in&lt;br&gt;&#xA;A330 - CF6 - 105 in&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between the CFM56 and CF34 isn't that great, but I think your image of the 737 isn't the best for comparison. If you look at an image more comparable to the CF34 picture you have, &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/7/78/Boeing_737-400_Engine.JPG&quot; rel=&quot;nofollow&quot;&gt;like this one&lt;/a&gt;, they appear much more similar.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-12-04T15:52:26.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23398" PostTypeId="1" AcceptedAnswerId="23399" CreationDate="2015-12-04T16:03:11.680" Score="12" ViewCount="3337" Body="&lt;p&gt;This has been one of my fears in flying (a plane the size of Cessna 152). I sort of know what to do when the engine quits on you when you are a few hundred feet off the ground, although it is definitely not easy to manage. However, lets say you are just past the rotation speed and have very little runway left. Is there anything you can really do other than cut power, retract flaps and try not to set your brakes on fire?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I am assuming that I am barely 10 feet above the runway. I suppose this is a more specific version of the general case of engine failure at lift-off. &lt;/p&gt;&#xA;" OwnerUserId="12277" LastEditorUserId="12277" LastEditDate="2015-12-04T16:57:38.210" LastActivityDate="2015-12-04T18:15:54.697" Title="What do you do when your engine quits right when the airplane starts off the ground?" Tags="&lt;flight-training&gt;&lt;general-aviation&gt;&lt;pilots&gt;&lt;single-engine&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23399" PostTypeId="2" ParentId="23398" CreationDate="2015-12-04T16:12:31.837" Score="18" Body="&lt;p&gt;The first and perhaps most important thing to do is &lt;strong&gt;&lt;em&gt;NOT turn around&lt;/em&gt;&lt;/strong&gt;. Generally speaking you won't have the airspeed/altitude to make a full 180 and return to the field. While it can be done, it's advised to continue forward and put the plane down as you would in any emergency. Trim for best glide and pick a landing spot (limited options in this case). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases with small plane/long runway situations you will be able to execute something like a short field landing with the remaining runway but that is very situationally dependent. When I flew out of KPNE in a Warrior 24 was 7000ft; if you lost an engine at rotation you had plenty of runway. At DYL where I fly now that's not really the case. Every airport is different but a good deal of the airports I have flown out of recently have had long fields at either end of the runway giving maybe an extra 1000 ft or so. Airports in populated areas may have roads you can touch down on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should always consult the POH of the specific aircraft in this case for proper emergency procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically to the 152 point, the take off distance is around 1400 ft. full loaded if memory serves. Unless you are training on 2000 ft strips you should have no problem getting the plane back down with remaining runway at all but the shortest of fields. If you are only 10ft up you should be able to put the plane down fast, albeit a bit hard, but fast none the less. For what it's worth &lt;a href=&quot;https://www.youtube.com/watch?v=Kx5YeqTBcDI&quot;&gt;Cessna landing gear can take quite a beating&lt;/a&gt;. Once you have touched down it would be advised to retract your flaps, this will increase the load on the gear (by reducing your wings' effectiveness) and increase brake effectiveness. You should take care to not lock the brakes as well.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Side Story&lt;/em&gt;: This happened to a buddy of mine in his Archer a bunch of years back (I'll try to find the incident report). The plane was fresh out of annual and something was not hooked up correctly and shook loose on take off causing the engine to cut out around 100ft or so. There was a corn field dead ahead and he was able to put the plane down smoothly. Thankfully no one was hurt and he simply owed the farmer for the corn he took out on landing&amp;hellip;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="4474" LastEditDate="2015-12-04T18:15:54.697" LastActivityDate="2015-12-04T18:15:54.697" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23400" PostTypeId="2" ParentId="23385" CreationDate="2015-12-04T16:13:20.120" Score="6" Body="&lt;p&gt;Reiterating the point made by @aeroalias, the &quot;weight&quot; that FAA/manufacturer talks about is really &quot;mass&quot; in the pure physics world. However, in the real world, imagine you have a big enough scale to hang the airplane to. The MTOW or Max Take Off Weight would be the reading on that scale. So, if you are weighing your passengers' baggage, use a reliable scale. You can then use it directly in your weight and balance calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, don't worry about conversions. Just use the real world &quot;weight&quot; in Kgs or Lbs as the case may be as long you are flying on earth.&lt;/p&gt;&#xA;" OwnerUserId="12277" LastEditorUserId="12277" LastEditDate="2016-06-03T16:19:28.107" LastActivityDate="2016-06-03T16:19:28.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23401" PostTypeId="2" ParentId="23398" CreationDate="2015-12-04T16:16:57.573" Score="11" Body="&lt;p&gt;If the engines quits right after the plane has lift off, you can easily set it back onto the runway. You will be amazed how short the distance is to stop a C152.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would rather leave the flaps untouched and focus on where I am going, unless you are a skilled bush pilot used to playing around with the flaps. Then again, if you are a skilled bush pilot, you should have no problem landing in incredible short distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, being a Cessna 152, chances are your runway can accommodate planes of larger size, like a Cessna Caravan, so you're likely to have some runway left. Unless you messed up your takeoff performance calculation, &lt;em&gt;&quot;just past rotation speed with very little runway left&quot;&lt;/em&gt; sounds a bit remote to me. If the engine quits by the time you reach the end of the runway, you should be at least a couple hundred feet high, making a turn possible. Oh yea, make sure you experiment this turn at altitude, so you don't commit to the impossible!&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2015-12-04T16:16:57.573" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23402" PostTypeId="1" AcceptedAnswerId="23551" CreationDate="2015-12-04T17:33:49.297" Score="17" ViewCount="6091" Body="&lt;p&gt;In an answer to a questions about turbulence &lt;a href=&quot;https://aviation.stackexchange.com/questions/1893/how-does-a-commercial-flight-pilot-handle-turbulence/1903#1903&quot;&gt;this answer&lt;/a&gt; mentioned that aircraft use radar to help detect the most turbulent areas of a storm so that pilots can avoid them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does radar do this?  Does it have to do with rain inside the storm moving up and down with the wind?  And if so, can radar detect wind speeds outside of a storm at all?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2018-06-18T16:37:02.437" Title="How does radar detect turbulence and wind speed?" Tags="&lt;weather&gt;&lt;turbulence&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23403" PostTypeId="2" ParentId="23402" CreationDate="2015-12-04T17:56:58.357" Score="9" Body="&lt;p&gt;The short answer is that radar cannot directly observe the wind.  What radar can detect is the velocities of small particles lofted into the air.  This is done by measuring the doppler shift of the energy returned to the radar.  The radar can only detect the component of velocity toward or away from the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radar doesn't have to diagnose turbulence within convection, as that is assumed to be there already and is part of the nature of convection.  It is much more valuable to detect clear air turbulence which does not have the visual indications that boiling cumulus growth does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully, clear air generally isn't exactly clear.  If there are aerosols or bugs that are large enough to scatter radar energy then the radar can infer their motion as the wind's motion.  For small things like dust and insects this isn't a bad approximation.  The return energy of these scatterers is very small and is generally below the threshold that the radar display will plot (unlike birds or bats), but the computers can interpret the data.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The detection of turbulence is algorithmic, and while I do not have knowledge of specific algorithms used, my first order guess is that they look at the variation in doppler velocity with distance from the airplane and they look at the time-series of doppler velocities at each sampled location in subsequent scans.  If the variation meets some criteria this could be classed as &quot;turbulence&quot; and provide an alert to the pilots.&#xA;The ability of such a system also depends on the physical capabilities of the radar including the wavelength the radar operates at, its sampling resolution and the sampling rate.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-04T17:56:58.357" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23404" PostTypeId="1" AcceptedAnswerId="23405" CreationDate="2015-12-04T18:12:31.833" Score="6" ViewCount="2489" Body="&lt;p&gt;Lets say that a private pilot owns a large commercial-type aircraft like the B777. Can he fly such a plane for himself as a private plane?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-12-04T18:28:20.037" Title="Can a private pilot fly commercial-type aircraft?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23405" PostTypeId="2" ParentId="23404" CreationDate="2015-12-04T18:18:48.377" Score="13" Body="&lt;p&gt;Your certificate level determines the type of operations you can conduct*, not the type of airplanes you can fly.  The types of airplanes you can fly are determined by your category, class and type ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have a Private Pilot certificate with an instrument rating (not sure if this is required, but you'll want it either way) and an airplane multi-engine land category and class and a B777 type rating, then yes, that person can operate the aircraft privately.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He will also need an SIC and he will only be able to collect the pro-rata share of operating expenses from people he carries.  He will also want to be careful in who he lets on his plane to avoid operations that are regulated under 14 CFR 119. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of such a pilot is John Travolta, who has a private pilot certificate with the following ratings:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;PRIVATE PILOT&#xA;  AIRPLANE SINGLE ENGINE LAND&#xA;  AIRPLANE MULTIENGINE LAND&#xA;  INSTRUMENT AIRPLANE&#xA;&#xA;Type Ratings:&#xA;P/B-707 P/B-720 P/CE-500    P/CL-600    P/EA-500S&#xA;P/G-1159    P/HS-125    P/LR-JET&#xA;&#xA;Limits:&#xA;ENGLISH PROFICIENT.&#xA;AUTHORIZED EXPERIMENTAL AIRCRAFT: SO-G2.&#xA;B-707 SIC PRIVILEGES ONLY.&#xA;CE-500 (VFR ONLY).&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;* Private pilots may only collect pro-rata operating expenses, Commercial pilots may be paid to act as PIC and ATPs may act as PIC in 14 CFR 121 operations.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-12-04T18:28:20.037" LastActivityDate="2015-12-04T18:28:20.037" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23406" PostTypeId="1" CreationDate="2015-12-04T20:54:43.250" Score="4" ViewCount="594" Body="&lt;p&gt;When an airport is open to the public, it is &lt;strong&gt;generally&lt;/strong&gt; owned and operated by a government entity. If the local government leases or sells the airport, this would generate significant amounts of revenue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the legal impediments which discourage a local government (who owns a public airport) from leasing or selling their airport to a private entity?&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="3825" LastEditDate="2015-12-04T23:29:51.877" LastActivityDate="2016-06-30T03:55:19.913" Title="What prevents a government from selling/leasing publicly owned airports?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;&lt;usa&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23407" PostTypeId="1" AcceptedAnswerId="23408" CreationDate="2015-12-04T21:16:19.930" Score="0" ViewCount="92" Body="&lt;p&gt;During my PPL training, We practiced some emergency procedure on Piper cherokee and simulated flight controls failure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My instructor asked me to sit on one hand and place the other on the trimmer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had to fly the aircraft using only rudder and trimmer, using trimmer and power for pitching and rudder for direction until short final. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is... Can the same procedure be exercised on big aircraft like Boeing?&lt;/p&gt;&#xA;" OwnerUserId="11492" LastEditorUserId="12220" LastEditDate="2015-12-04T22:06:44.883" LastActivityDate="2015-12-04T22:17:16.143" Title="Can trimmer and throttle be used for controlling large aircraft" Tags="&lt;flight-training&gt;&lt;flight-controls&gt;&lt;boeing&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-12-07T03:12:56.777" ContentLicense="CC BY-SA 3.0" />
  <row Id="23408" PostTypeId="2" ParentId="23407" CreationDate="2015-12-04T21:22:24.583" Score="0" Body="&lt;p&gt;To some extent, yes. There was &lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;nofollow&quot;&gt;United Airlines Flight 232&lt;/a&gt; in which catastrophic failure in the tail engine destroyed all the hydraulic lines. The plane was crash-landed in Sioux City, Iowa after the pilots controlled the aircraft using only the two intact wing engines. The trimmer might not produce as large as an effect on larger aircraft as on smaller ones; control of the engines would be enough because they affect the aircraft more than the trimmer due to their thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if the damage is so severe that a control surface is destroyed or locked into a certain position, the engines might not be able to counteract that.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-04T22:17:16.143" LastActivityDate="2015-12-04T22:17:16.143" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23409" PostTypeId="1" CreationDate="2015-12-04T21:24:38.683" Score="3" ViewCount="3452" Body="&lt;p&gt;I know that ALL airports that have received federal funds are considered to be open to the public, however does that mean that every &quot;public&quot; airport was federally funded?&lt;/p&gt;&#xA;" OwnerUserId="12239" LastActivityDate="2015-12-05T00:20:36.367" Title="What is a public airport?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;&lt;usa&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23410" PostTypeId="2" ParentId="23406" CreationDate="2015-12-04T21:28:28.600" Score="5" Body="&lt;p&gt;One possible impediment might be the &lt;a href=&quot;http://www.faa.gov/airports/aip/overview/#what_obligations&quot; rel=&quot;noreferrer&quot;&gt;grant assurances&lt;/a&gt; that come with accepting Federal aid to improve the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, if the local airport accepts money from the Federal government to improve the airport, that money is often granted &quot;with strings attached&quot; - requirements that the airport remain open, etc.  &lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2015-12-04T21:28:28.600" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23411" PostTypeId="2" ParentId="23409" CreationDate="2015-12-04T21:38:37.757" Score="3" Body="&lt;p&gt;You can check out &lt;a href=&quot;http://www.faa.gov/airports/planning_capacity/passenger_allcargo_stats/categories/&quot; rel=&quot;nofollow&quot;&gt;this info from the FAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the official &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b2cb8152647a629841014d86a11ab17b&amp;amp;mc=true&amp;amp;node=se14.2.77_13&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;FAA definition&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Public use airport is an airport available for use by the general&#xA;  public without a requirement for prior approval of the airport owner&#xA;  or operator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It should be noted that 4 airports in the US are considered &quot;High Density&quot; and have &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=c1711998db72c9e4b6e777ef4c4ce750;rgn=div5;view=text;node=14:2.0.1.3.11;idno=14;cc=ecfr#se14.2.93_1123&quot; rel=&quot;nofollow&quot;&gt;special rules about operations during certain times&lt;/a&gt; which require approval for use (arrival/departure) despite being public. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§93.125   Arrival or departure reservation.&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Except between 12 Midnight and 6 a.m. local time, no person may&#xA;  operate an aircraft to or from an airport designated as a high density&#xA;  traffic airport unless he has received, for that operation, an arrival&#xA;  or departure reservation from ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In answer to the question as its now worded, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, there are public airports that are not federally funded. The airport I currently fly out of &lt;a href=&quot;https://en.wikipedia.org/wiki/Doylestown_Airport&quot; rel=&quot;nofollow&quot;&gt;KDYL&lt;/a&gt; is owned and operated by the local government (Bucks County) and they are responsible for most things that go on there. I am not sure if they have received Federal funding in the past but I will ask around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also such thing as &quot;&lt;a href=&quot;http://www.aopa.org/-/media/Files/AOPA/Home/News/All-News/2006/AOPA-Online-Members-Only-AOPA-ePilot-Flight-Training-Edition-Vol-6-Issue-1/060103airports-paper.pdf&quot; rel=&quot;nofollow&quot;&gt;Privately Owned/Publicly Used&lt;/a&gt;&quot; (elsewhere called &lt;a href=&quot;https://en.wikipedia.org/wiki/Privately_owned_public_space&quot; rel=&quot;nofollow&quot;&gt;POPS&lt;/a&gt;) airports like &lt;a href=&quot;https://en.wikipedia.org/wiki/Trenton%E2%80%93Robbinsville_Airport&quot; rel=&quot;nofollow&quot;&gt;Trenton Robbonsville N87&lt;/a&gt;. These airports are owned privately, run privately, and generate their own income however you don't need to prior approval to land there and are open to general public use. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-05T00:20:36.367" LastActivityDate="2015-12-05T00:20:36.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23412" PostTypeId="1" AcceptedAnswerId="23453" CreationDate="2015-12-04T22:41:35.673" Score="4" ViewCount="1129" Body="&lt;p&gt;I wonder whether &lt;a href=&quot;https://en.wikipedia.org/wiki/Michael_O%27Leary_(Ryanair)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Michael O'Leary&lt;/a&gt; has already seen that. I am pretty sure he would be eager to implement the idea. However, is that feasible - both from a legal, and as a security policy - for commercial planes transporting civilians? Maybe military personnel can be trusted to evacuate the plane faster than average civilians in case of emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mXp2g.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mXp2g.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;https://www.dailymail.co.uk/news/article-2121412/Room-Stunning-pictures-U-S-troops-crammed-military-plane-fly-Afghanistan.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;dailymail.co.uk&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="14897" LastEditDate="2019-02-12T17:54:57.250" LastActivityDate="2019-02-12T18:42:32.453" Title="Could a commercial plane seat configuration look like a troop carrier?" Tags="&lt;seats&gt;&lt;low-cost-carrier&gt;&lt;seating-capacity&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23413" PostTypeId="1" CreationDate="2015-12-04T22:55:45.890" Score="0" ViewCount="338" Body="&lt;p&gt;I would like to know all existing technological means of defending an area against the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Atomics_MQ-9_Reaper&quot; rel=&quot;nofollow noreferrer&quot;&gt;MQ-9 Reaper&lt;/a&gt; or other hunter-killer unmanned aerial vehicles (UAVs) used by the United States in countries like Afghanistan, Syria, etc. Such means should either force the UAVs to leave the area or crash.&lt;/p&gt;&#xA;" OwnerUserId="12538" LastEditorUserId="15311" LastEditDate="2017-12-24T15:57:54.723" LastActivityDate="2017-12-24T15:57:54.723" Title="Means of protection against hunter-killer UAVs" Tags="&lt;military&gt;&lt;airspace&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="6" ClosedDate="2015-12-05T04:15:49.860" ContentLicense="CC BY-SA 3.0" />
  <row Id="23414" PostTypeId="2" ParentId="23413" CreationDate="2015-12-04T23:35:20.767" Score="5" Body="&lt;p&gt;By far the cheapest method for protecting a limited area would be to use an aerostat to carry aloft a jammer. Vehicles like the Reaper rely on a satellite uplink to maintain their command and control. As long as the aerostat is well above the altitude of the Reaper it can easily jam it. The cost of this option might be around \$1 million with an annual operating cost of \$200,000 and an effective diameter of about 10-20 miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more expensive, but more flexible response would be to just shoot it down. To do this you would need an air surveillance radar, a high performance turboprop with machine guns like a Texan or Super Tucano, a pilot and a crew to operate the radar. With this method you could deny a pretty large area, maybe 100 miles in diameter easily, possibly more. The cost of this would be about \$3 to \$5 million plus annual operating costs of about $500,000. If you want to spend a bit a more a Yak-130 would be an excellent light attack jet to consider for anti-drone work. You might be able to find a used Yak for under \$10 million and it is a bitchin aircraft that can go double the speed of a Predator plus it has its own radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Missile systems would not really work because the types you would need to reach the altitude a Reaper operates at, are very expensive and complex (which is exactly why the Reaper flies at those altitudes). However if you could catch the Reaper while it was taking off or landing, a small missile like an RBS 70 would be even cheaper, assuming you could obtain that weapon.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-12-05T00:07:07.020" LastActivityDate="2015-12-05T00:07:07.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23415" PostTypeId="2" ParentId="23413" CreationDate="2015-12-04T23:56:11.877" Score="4" Body="&lt;p&gt;A drone is practically a type of aircraft and can be shot down using the same means as shooting down aircraft, and then some, like&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;missiles (surface to air or air to air).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If they are flying low, &lt;a href=&quot;https://en.wikipedia.org/wiki/Pantsir-S1&quot; rel=&quot;nofollow&quot;&gt;using guns&lt;/a&gt; in point or area defense weapons,&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are some other defensive measures under development like &lt;a href=&quot;https://en.wikipedia.org/wiki/Laser_Weapon_System&quot; rel=&quot;nofollow&quot;&gt;laser&lt;/a&gt; and &lt;a href=&quot;http://www.wired.com/2009/02/microwaves-vs-d/&quot; rel=&quot;nofollow&quot;&gt;microwave&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of UAVs being controlled remotely (as most of them are), the signals can be jammed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-04T23:56:11.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23416" PostTypeId="2" ParentId="23406" CreationDate="2015-12-05T00:30:44.017" Score="3" Body="&lt;p&gt;Some places have land laws that protect public spaces as well as &lt;a href=&quot;https://en.wikipedia.org/wiki/Privately_owned_public_space&quot; rel=&quot;nofollow&quot;&gt;Privately Owned Public Spaces&lt;/a&gt;. For example there are Privately Owned Public Use Airports in the US like T&lt;a href=&quot;https://www.airnav.com/airport/N87&quot; rel=&quot;nofollow&quot;&gt;renton-Robbinsville N87&lt;/a&gt;. In some cases the laws may not prevent the rental to a private organization but may require that the airport remain in public use. IN this case the government may not want to rent/sell it since it needs to remain a public entity anyway. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-12-05T00:30:44.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23417" PostTypeId="1" AcceptedAnswerId="23418" CreationDate="2015-12-05T00:51:21.257" Score="19" ViewCount="50021" Body="&lt;p&gt;Why does the military use hydrazine to power the F-16's Emergency Power Unit (EPU)? What is so unique about Hydrazine fuel that it's  needed to power the EPU? Why not use a less volatile and less hazardous fuel?  &lt;/p&gt;&#xA;" OwnerUserId="8247" LastEditorUserId="15311" LastEditDate="2020-04-04T13:10:15.993" LastActivityDate="2020-04-04T13:10:15.993" Title="Why is Hydrazine used to power the F-16's EPU?" Tags="&lt;military&gt;&lt;electrical-system&gt;&lt;f-16&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23418" PostTypeId="2" ParentId="23417" CreationDate="2015-12-05T01:17:50.023" Score="20" Body="&lt;p&gt;The EPU of F-16 is fueled with a monopropellant hydrazine mixture, H-70, which contains 70% hydrazine ($N_{2}H_{4}$) and 30% water, by weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main requirements for the EPU are that it should be simple, maintenance free, supply power immediately and consistently for the required time. Use of Hydrazine assures this while requiring careful handling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the catalytic decomposition of hydrazine produces ammonia, nitrogen and hydrogen. Exhuast Gases from EPU Turbine contain 40% Ammonia, 17% Nitrogen, 15% Hydrogen and 28% Water. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$3N_{2}H_{4} \rightarrow 4NH_{3} + N_{2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$4NH_{3} \rightarrow 2N_{2} + 6H_{2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$3N_{2}H_{4} \rightarrow 4(1-x)NH_{3} + 6xH_{2} + (2x+1) N_{2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where x is the fraction of the $NH_{3}$ disassociated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The water modifies the decomposition temperature (the EPU reaches temperatures of ~870 $^{\circ}C$), preventing thermal damage to the catalyst bed and the turbine parts. As the water removes heat, it is turned into steam which aids in powering the EPU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EPU, using hydrazine spins up to approximately 75,000 rpm in 2-3 seconds (The F-16 EPU starts within 2 sec.). It would take a much greater time if another fuel, like JP-8 were used. When required (EPU runs normally on engine bleed air), hydrazine is &lt;a href=&quot;http://www.f-16.net/forum/download/file.php?id=3433&amp;amp;sid=b6af33b232f0538d3c91d8a88a132edb&quot; rel=&quot;noreferrer&quot;&gt;forced into decomposition chamber by nitrogen pressure&lt;/a&gt;, where the above reactions produce the gases to run the turbine/gearbox. The decomposition of hydrazine produces enough pressure, eliminating the need for a compressor, thus saving weight and also eliminating the need for an igniter, reducing complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the given weight, it provides continuous operation for the required time. In F-16, the EPU carries ~25l of hydrazine, which permits operation for about 10 minutes under normal load conditions and 15 minutes if the loads are less (i.e. in ground). If any other form, (like battery or cartridge) were used, it would be difficult to have a long operational time without heavy increase in mass. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a combat aircraft, RAT is not an option. Also, a hydrazine powered EPU would work in any altitude or during maneuvering as it does not need an external oxidizer supply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Exhaust Gas Composition of the F-16 Emergency Power Unit&lt;/em&gt; by Harry J. Suggs et al.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Technical Order 00-105E-9, USAF&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AFR 110-14 USAF Aircraft Accident Investigation Report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-16 &lt;a href=&quot;http://www.slideshare.net/matheusgaldino355/usaf-flight-manual-f16&quot; rel=&quot;noreferrer&quot;&gt;manual&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to @Peter for pointing out errors.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="946" LastEditDate="2016-01-15T15:56:12.690" LastActivityDate="2016-01-15T15:56:12.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23419" PostTypeId="2" ParentId="23413" CreationDate="2015-12-05T02:43:40.693" Score="2" Body="&lt;h3&gt;This is a Glock 19.  Cost: $350&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VSvRS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VSvRS.jpg&quot; alt=&quot;Picture of a Glock 19&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;This is a 9mm bullet.  The Glock holds 15 of them. Cost: $12.99 for a box of 50&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8DF2s.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8DF2s.jpg&quot; alt=&quot;Picture of a 9mm bullet&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;This is the ground control station for a Predator drone.&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BrupS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BrupS.jpg&quot; alt=&quot;Picture of the outside of a UAV ground control station&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h3&gt;And this is what it looks like on the inside.&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MMkvf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MMkvf.jpg&quot; alt=&quot;Picture of a Predator ground control console&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h1&gt;The Cheapest Way To Bring Down A Hunter-Killer UAV&lt;/h1&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/ygI-2F8ApUM?t=7s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Go to the ground control station&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/3JKLFnWKUaQ?t=12m58s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shoot everything&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/sOUoNy7EmPA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Take control of the UAV&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://youtu.be/PZrS4pFbnBM?t=6m40s&quot; rel=&quot;nofollow noreferrer&quot;&gt;Crash the UAV&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;Total cost: $362.99&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-05T02:43:40.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23420" PostTypeId="1" CreationDate="2015-12-05T05:18:02.967" Score="6" ViewCount="5513" Body="&lt;p&gt;Does anyone know where I could find where the highest rates of bird strikes are?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along the same lines, other wildlife, such as moose or bears on runways?&lt;/p&gt;&#xA;" OwnerUserId="12542" LastActivityDate="2019-07-29T18:02:22.830" Title="How many bird strikes are there per year? Any world-wide statistics?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23421" PostTypeId="2" ParentId="23417" CreationDate="2015-12-05T09:40:52.393" Score="32" Body="&lt;p&gt;To fill the voids in aeroalias' answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydrazine is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Monopropellant&quot; rel=&quot;noreferrer&quot;&gt;monopropellant&lt;/a&gt;, something which does not need to be mixed and burned to free up the energy contained in its chemical bonds. This energy is freed by letting the hydrazine stream over a &lt;a href=&quot;https://en.wikipedia.org/wiki/Catalysis&quot; rel=&quot;noreferrer&quot;&gt;catalyst&lt;/a&gt;, in case of the F-16 EPU that is &lt;a href=&quot;https://en.wikipedia.org/wiki/Iridium#Industrial_and_medical&quot; rel=&quot;noreferrer&quot;&gt;iridium&lt;/a&gt;. This breaks the chemical bond, &lt;a href=&quot;http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&amp;amp;doc=GetTRDoc.pdf&amp;amp;AD=ADA065595&quot; rel=&quot;noreferrer&quot;&gt;producing ammonia, nitrogen gas, hydrogen gas and heat&lt;/a&gt; which converts the water into steam. Heating increases the volume of the gasses and the steam so they pick up speed, just like the gasses in the &lt;a href=&quot;https://physics.stackexchange.com/questions/114280/why-do-turbine-engines-work/159822#159822&quot;&gt;combustion chamber of a jet engine&lt;/a&gt;. In the catalyst chamber of the F-16's EPU the temperature reaches more than 800°C in just a couple of milliseconds, and no combustion is involved! This high-pressure, high-speed gas flows through a small turbine which in turn drives a generator and supplies hydraulic pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compression is not needed because pressure is supplied from the bottle containing the hydrazine-water mixture. Using a monopropellant also avoids any ignition problems and makes the setup very simple. Since hydrazine is quite stable at high pressure and ambient temperature, the shelf life of a hydrazine engine is high, and the liquid state of the hydrazine-water mixture makes its storage very compact. Just what you need in a fighter aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2015-12-05T11:03:50.883" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23423" PostTypeId="1" AcceptedAnswerId="23425" CreationDate="2015-12-05T17:58:23.230" Score="5" ViewCount="3782" Body="&lt;p&gt;Many successful fighter aircraft, eg F/A-18 Hornet, have 2 crew (pilot and navigator), which (from my albeit limited research) gave great benefit in complex situations especially involving ground defences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35 Lightning II is supposed to be multi-purpose, but has only 1 crew - why?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do the advanced electronics compensate for the lack of a navigator?&lt;/li&gt;&#xA;&lt;li&gt;Would the design (aerodynamics/frame) be compromised by adding another seat?&lt;/li&gt;&#xA;&lt;li&gt;Something else?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12550" LastActivityDate="2018-11-17T21:35:33.500" Title="Why does the F-35 Lightning II have only 1 crew when the F/A-18 Hornet had 2?" Tags="&lt;crew&gt;&lt;f-35&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-12-05T20:07:27.927" ContentLicense="CC BY-SA 3.0" />
  <row Id="23424" PostTypeId="1" CreationDate="2015-12-05T18:51:07.707" Score="4" ViewCount="438" Body="&lt;p&gt;I am asking this for someone I know who's up in years but still under 60, and is a fellow pilot.  He brought this question up:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;I am concerned that I might have some moderate sleep problems - doubtful it's narcolepsy, and I've driven (and flown) safely for years and the worst is feeling tired.  My thought is to check on blood levels and maybe EKG stuff etc..  Perhaps there is something that's actually detectable.  Perhaps there is medication that reduces the tiredness.  If I go to a doctor and bring these up, will it jeopardize my medical?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your thoughts?  Appreciate your feedback - my friend is not an internet person at all :)&lt;/p&gt;&#xA;" OwnerUserId="9243" LastEditorUserId="167" LastEditDate="2015-12-06T18:03:39.823" LastActivityDate="2016-03-26T04:05:32.037" Title="Will talking about sleep problems with my doctor jeopardize my medical?" Tags="&lt;medical&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23425" PostTypeId="2" ParentId="23423" CreationDate="2015-12-05T19:21:05.247" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Why does the F-35 Lightning II have only 1 crew when the F/A-18 Hornet had 2?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.flightglobal.com/news/articles/israel-sets-sights-on-two-seater-f-35-337464/&quot; rel=&quot;nofollow noreferrer&quot;&gt;program officials&lt;/a&gt; involved in the development of the F-35, the F-35 is a single seat aircraft because:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;New advances in avionics and sensor fusion technology, which can &#xA;  allow  a single pilot to perform missions that previously required two&#xA;  crew members&lt;/em&gt;.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Given the fact that the F-35 is build around the concept of&#xA;&lt;strong&gt;&lt;a href=&quot;https://www.f35.com/news/detail/the-f-35-vs.-the-vhf-threat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Network Centric Warfare&lt;/a&gt;&lt;/strong&gt; there is less cockpit workload for most strike missions. Consequently, the need for a co-pilot is a lot less. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The single-seat configuration also maximizes commonality between the &#xA;three variants of the F-35 thereby keeping development costs low.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The survivability of the F-35 includes limiting the probability of   detection. Ergo, a two-seater version can very easily increase the RCS of the F-35 thereby compromising its stealth capabilities&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?time_continue=9&amp;amp;v=Vxe4Jv1cJxI&quot; rel=&quot;nofollow noreferrer&quot;&gt;West 2014: Joint Strike Fighter: What Do the Pilots Who Are Flying It Today Have to Say?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, one major drawback that remains on the one seat &lt;a href=&quot;https://ericpalmer.files.wordpress.com/2009/10/needforf35twoseatvariant2008.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;design&lt;/a&gt; is the demand on one &lt;a href=&quot;https://www.f35.com/resources/test-pilot-tuesdays&quot; rel=&quot;nofollow noreferrer&quot;&gt;pilot&lt;/a&gt; to assimilate and decide on all the information available.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="11215" LastEditDate="2018-11-17T21:35:33.500" LastActivityDate="2018-11-17T21:35:33.500" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23426" PostTypeId="1" AcceptedAnswerId="23435" CreationDate="2015-12-05T19:35:14.630" Score="8" ViewCount="13979" Body="&lt;p&gt;Most large aircraft have a wind direction and wind speed indicator. How is this measured? The vector difference between TAS and ground speed? How accurate is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the below picture (taken from &lt;a href=&quot;https://aviation.stackexchange.com/questions/15201/how-is-the-actual-ground-speed-of-an-airliner-measured&quot;&gt;this question&lt;/a&gt;) it is displayed in the top-left corner of the top-right quadrant (just below the TAS and GS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6si2P.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6si2P.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11665" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2021-02-21T11:51:19.463" Title="How is the wind direction and wind speed measured in flight?" Tags="&lt;flight-instruments&gt;&lt;wind&gt;&lt;measurement&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23427" PostTypeId="1" AcceptedAnswerId="23430" CreationDate="2015-12-05T19:47:21.243" Score="8" ViewCount="1907" Body="&lt;p&gt;I read somewhere that conventional aircraft are designed so that the main wing always stalls before the tailplane. Why is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My concern is that if the wing stalls, suddenly the tail will push the aircraft into a higher AoA, and maybe stall itself, though the pilot would still have control for some time to avoid that. On the other hand, if the tail stalls, the plane will (violently?) pitch down, but would be able to recover afterward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what am I missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Assume the center of gravity of the plane is in front of the main wing&lt;/p&gt;&#xA;" OwnerUserId="12551" LastEditorUserId="167" LastEditDate="2015-12-06T18:04:48.550" LastActivityDate="2015-12-06T20:57:17.813" Title="Why are aircraft designed so that the wing stalls before the tail?" Tags="&lt;stall&gt;&lt;stability&gt;&lt;tail&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23428" PostTypeId="1" AcceptedAnswerId="23617" CreationDate="2015-12-05T19:54:45.057" Score="2" ViewCount="203" Body="&lt;p&gt;In 3 days I will have my Class 1 JAA medical test for the first time. However I said let's do a heart checkup before I go there and when I did this suddenly my cardiologist wrote that I have:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Anterior mitral leaflet is slightly redundant and shows mild systolic prolapse. Trivial mitral regurgitation present.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He did for me a TMT and my performance was 97% as I'm 23 years old my heart rate increased to 195 bpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He told me this will not affect your pilot studies and nothing to worry about because it is normal and if you want to check it again, check it after 4 years, however no need to check it again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I'm worried, will they stop me if they found out about this or what will happen? &lt;/p&gt;&#xA;" OwnerUserId="12552" LastEditorUserId="167" LastEditDate="2015-12-06T18:02:43.803" LastActivityDate="2015-12-13T00:25:47.317" Title="Will this diagnosis from my cardiologist prevent me from getting a Class 1 JAA medical?" Tags="&lt;medical&gt;&lt;ppl&gt;&lt;cpl&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23429" PostTypeId="1" CreationDate="2015-12-05T20:19:50.537" Score="9" ViewCount="2937" Body="&lt;p&gt;I recently saw a ferry permit which included the following limitation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;Flight in IMC authorized for ENROUTE operations ONLY&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Great, IMC is allowed enroute!  But wait, where does the &quot;enroute&quot; portion of the flight start and end?  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I did some research and found the following &lt;a href=&quot;http://www.intlaviationstandards.org/Documents/PhaseofFlightDefinitions.pdf&quot;&gt;ICAO definition for enroute&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Instrument Flight Rules (IFR): From completion of Initial Climb&#xA;  through cruise altitude and completion of controlled descent to the&#xA;  Initial Approach Fix (IAF).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Visual Flight Rules (VFR): From completion of Initial Climb through&#xA;  cruise and controlled descent to the VFR pattern altitude or 1,000&#xA;  feet above runway elevation, whichever comes first.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That seems pretty straightforward, but I was looking for something FAA specific and found this in Chapter two of the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot;&gt;FAA's Instrument Procedures Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The en route phase of flight is defined as that segment of flight from&#xA;  the termination point of a departure procedure to the origination&#xA;  point of an arrival procedure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That doesn't match the ICAO definition, but it also isn't from an actual regulation or LOI either.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This leaves arrivals and departures as slightly ambiguous, and they often start high in the flight levels where it can be hard to avoid IMC, even on a nice VFR day at the airport (and also seems contrary to what they are trying to accomplish).  Are arrivals and departures considered enroute or some other phase of flight?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2017-12-17T06:34:33.140" Title="What is the official FAA definition of the term enroute?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23430" PostTypeId="2" ParentId="23427" CreationDate="2015-12-05T20:48:32.693" Score="16" Body="&lt;p&gt;You are missing the weight force. The wing should stall first because then it will produce less lift and the weight will make the aircraft pitch down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In attached flow, the lift from wing and tail is &lt;a href=&quot;https://aviation.stackexchange.com/questions/11713/can-the-design-for-neutral-stability-reduce-trim-drag/11721#11721&quot;&gt;balanced&lt;/a&gt; such that the combined resulting force is acting exactly at the longitudinal position of the center of gravity. If the wing stalls, the balance of lift is shifted backwards (regardless of the tail producing lift or a downforce), because now the forward part of the wing-tail-combination will produce proportionally less lift than it did in attached flow. The center of gravity will then be ahead of the resulting lift force and will pull the nose of the aircraft down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tail stall is bad news for the pilot and should be avoided:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A stalled tail will have much less elevator effectivity, reducing the control power available to the pilot&lt;/li&gt;&#xA;&lt;li&gt;A stalled tail at high angle of attack is stalling at maximum lift, so it produced positive lift before. If it stalls, its lift will shrink and make the aircraft pitch up.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In a conventional configuration the tail flies in the flow field of the wing. Because the wing's &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=3%7C0.0560#8882&quot;&gt;downwash increases with angle of attack&lt;/a&gt;, the angle of attack variations at the tail are reduced. This helps to keep the flow at the tail attached over the whole useable angle of attack range of the wing. A tail stall is either caused by a wrong location of the center of gravity (CG) or by a very poor transsonic design which causes &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight/5004#5004&quot;&gt;shock-induced stalling of the tail&lt;/a&gt; when the wing is still doing fine. Very rarely can you stall the tail by a wrong trim setting when a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21114/why-do-some-fighter-jets-have-movable-horizontal-stabilzer-instead-of-elevators/21130#21130&quot;&gt;moveable stabilizer is used for trimming&lt;/a&gt;, or in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/8022/what-is-a-deep-stall-and-how-can-pilots-recover-from-it/8027?s=10%7C0.1305#8027&quot;&gt;deep stall&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some supersonic aircraft compensate for the backward shift of the center of lift in supersonic flow by pumping fuel from forward to rear. If an airplane with such a rear CG location slows down to subsonic speed, it will need to produce proportionally more lift with the tail than with the wing. If it now pitches up (say, for a tight turn) it will risk a tail stall. Note that such a configuration is &lt;a href=&quot;https://aviation.stackexchange.com/questions/12507/what-does-it-mean-for-a-plane-to-be-aerodynamically-stable/12511#12511&quot;&gt;aerodynamically unstable&lt;/a&gt; at subsonic speed.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you define the center of gravity as ahead of the wing, which makes for a very stable configuration. The tail is producing a downforce to compensate the pitch-down action of the wing's lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the wing stalls first, lift will become less than weight and the aircraft will accelerate downwards. Now the angle of attack will increase at both the tail and the wing; at the tail even for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The downward acceleration will change the local flow direction to a larger angle of attack, and&lt;/li&gt;&#xA;&lt;li&gt;The diminished downwash from the wing will cause an angle of attack increase of its own at the tail. This effect takes a little longer to manifest itself: The delay is the distance between the quarter points of tail and wing divided by the airspeed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Both effects will quickly create a dominant pitch-down moment for the aircraft because the tail will contribute much less downforce than before the stall, and the diminished pitch-down moment of the wing will become insignificant.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-12-06T20:57:17.813" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23431" PostTypeId="1" CreationDate="2015-12-05T20:48:50.993" Score="25" ViewCount="10162" Body="&lt;p&gt;Just boarded an A320 with many open seats (Spirit), and the flight attendant said we may not change seats until at altitude due to weight and balance.  Is he just trying to prevent pax from moving around while the crew is busy moving around the cabin, or is this a legitimate issue?  I feel it must be the former, in which case I feel they're being a bit deceptive. &lt;/p&gt;&#xA;" OwnerUserId="2686" LastEditorUserId="19" LastEditDate="2016-10-31T12:28:13.790" LastActivityDate="2019-12-23T20:48:06.123" Title="Are passengers really not allowed to change seats before take-off due to weight and balance?" Tags="&lt;airline-operations&gt;&lt;weight-and-balance&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23433" PostTypeId="2" ParentId="23431" CreationDate="2015-12-05T21:21:38.313" Score="24" Body="&lt;p&gt;The crew gave you the correct reason, but it would had taken a co-ordinated effort from the majority of the passengers to upset the aircraft's balance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in smaller aircraft even a single person moving around can shift the center of gravity outside its safe limits. The de Havilland company once produced such an aircraft, the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Express&quot; rel=&quot;noreferrer&quot;&gt;DH86 Express&lt;/a&gt;. Wikipedia reports:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 2 October 1935 Holyman's VH-URT Loina was also lost in Bass Strait,&#xA;  again with no survivors. This time a significant amount of wreckage&#xA;  was recovered from the sea and from beaches on Flinders Island.&#xA;  Investigation of the wreckage revealed a section of charred carpet on&#xA;  a piece of cabin flooring from just ahead of the lavatory door. It was&#xA;  thought possible that a small fire from a dropped cigarette had led to&#xA;  someone running aft suddenly to stamp it out – the sort of sudden&#xA;  change in weight distribution that could set up a fatal loss of&#xA;  directional control while the aircraft was on a low-speed landing&#xA;  approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A dramatic example what a shifting load can do to the controllability of an aircraft was &lt;a href=&quot;https://en.wikipedia.org/wiki/National_Airlines_Flight_102&quot; rel=&quot;noreferrer&quot;&gt;National Airlines Flight 102&lt;/a&gt;, a Boeing 747-400 freighter conversion which took off from Bagram on April 29, 2013. The most likely cause was insufficiently secured payload which shifted back when the aircraft pitched up during take-off. A single passenger will not be as heavy as a &lt;a href=&quot;https://en.wikipedia.org/wiki/MRAP&quot; rel=&quot;noreferrer&quot;&gt;MRAP&lt;/a&gt;, but several of them moving over a significant part of the cabin length in combination with a position of the center of gravity close to the limit could well upset the flight.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;CG at the forward limit, passengers moving to the front: The aircraft will need higher speed and much more elevator deflection for lift-off. Especially in combination with an engine failure late in the take-off run, a crash is a distinct possibility.&lt;/li&gt;&#xA;&lt;li&gt;CG at the rear limit, passengers moving to the back: The static stability and, in manually controlled aircraft, the stick forces are reduced. Flying the aircraft needs more attention, and in extreme cases the aircraft will become &lt;a href=&quot;https://aviation.stackexchange.com/questions/12507/what-does-it-mean-for-a-plane-to-be-aerodynamically-stable/12511?s=22%7C0.1146#12511&quot;&gt;longitudinally unstable&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In any case, the pilots need to adjust trim.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-06T14:54:58.133" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23435" PostTypeId="2" ParentId="23426" CreationDate="2015-12-05T21:38:02.713" Score="16" Body="&lt;p&gt;Indirectly, as the difference between true air speed and ground speed.&lt;/p&gt;&#xA;&lt;p&gt;Since aircraft cannot measure true air speed, several steps are needed to arrive at the correct wind speed:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The pitot tube (big aircraft have several of them) gives the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stagnation_pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;stagnation pressure&lt;/a&gt; of the air, which is the sum of static and dynamic pressure.&lt;/li&gt;&#xA;&lt;li&gt;The static ports (again, big aircraft have several of them) give the &lt;a href=&quot;https://en.wikipedia.org/wiki/Static_pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;static pressure&lt;/a&gt; of the ambient air, so the dynamic pressure can be isolated.&lt;/li&gt;&#xA;&lt;li&gt;With the static pressure and the ambient temperature the air density can be calculated.&lt;/li&gt;&#xA;&lt;li&gt;With the density it is now possible to calculate the &lt;a href=&quot;https://en.wikipedia.org/wiki/True_airspeed&quot; rel=&quot;nofollow noreferrer&quot;&gt;true air speed&lt;/a&gt; from the dynamic pressure.&lt;/li&gt;&#xA;&lt;li&gt;From the compass you get the heading of the aircraft, so you know the direction of the true air speed.&lt;/li&gt;&#xA;&lt;li&gt;The ground speed and track direction can be calculated by repeatedly measuring the location of the aircraft and dividing the distance by the time between measurements, or with modern aircraft it can be read directly from the GPS display.&lt;/li&gt;&#xA;&lt;li&gt;Wind speed and direction can be calculated by subtracting the true air speed vector from the ground speed vector.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;You will notice that there are a lot of possible sources of error in this procedure. All instruments involved have their own bias and scaling error. However, if everything is carefully calibrated and corrected, the result can be very accurate.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2021-02-21T11:51:19.463" LastActivityDate="2021-02-21T11:51:19.463" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23437" PostTypeId="1" CreationDate="2015-12-05T22:33:54.970" Score="21" ViewCount="23323" Body="&lt;p&gt;As far as I can tell, in the U.S., 49 USC &lt;a href=&quot;https://www.law.cornell.edu/uscode/text/49/46317&quot;&gt;46317(a)&lt;/a&gt; makes flying without a proper certificate a crime punishable by fine and/or imprisonment.  However, the FAA is a regulatory agency, which means it can only assess civil penalties (e.g., civil fines or revocation of certificates).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice I've heard (and would expect) the FAA gets quite exercised over &quot;airmen&quot; found to be carrying passengers for hire without current and proper certificates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm wondering is whether individuals have ever been, or are routinely, subject to any scrutiny or regulatory or prosecutorial action if they fly without certificates and don't commit any other egregious violations of FAA regulations?  E.g., if you only fly registered aircraft for your own amusement, and you never break a serious airspace rule, but you never get an FAA certificate, could you expect to go your whole life without any trouble from the FAA?  If not, what sort of trouble might you expect and how would you get into it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And has anyone &lt;em&gt;ever&lt;/em&gt; faced criminal prosecution for flying without proper certificates who did not also commit a gross violation of safety &lt;em&gt;while&lt;/em&gt; operating an aircraft for hire, or some other felony (e.g., smuggling)?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="19" LastEditDate="2016-07-08T11:43:28.710" LastActivityDate="2017-12-25T19:59:28.283" Title="What are the consequences of flying GA without a license (certificate)?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;general-aviation&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23438" PostTypeId="1" AcceptedAnswerId="23441" CreationDate="2015-12-05T22:44:03.540" Score="1" ViewCount="1041" Body="&lt;p&gt;A jet aircraft seems for sure very complex as such. But, referring Wikipedia, a &quot;complex aircraft&quot; (as legally defined) has:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A retractable landing gear&lt;/li&gt;&#xA;&lt;li&gt;Flaps&lt;/li&gt;&#xA;&lt;li&gt;and &lt;strong&gt;&lt;em&gt;A controllable pitch propeller&lt;/em&gt;&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And there is no propeller in a jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the reasons of defining &quot;complex aircraft&quot; so that it does not cover jets? Are these reasons other than historical?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="3825" LastEditDate="2015-12-05T22:53:58.233" LastActivityDate="2015-12-06T09:06:51.117" Title="Are jets deliberately excluded from the &quot;Complex airplane&quot; definition?" Tags="&lt;regulations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23439" PostTypeId="2" ParentId="23429" CreationDate="2015-12-06T00:04:10.957" Score="3" Body="&lt;p&gt;FAA follows the ICAO definition for describing the phases of flight.&lt;/p&gt;&#xA;&lt;p&gt;FAA is a member of the CAST/ICAO Common Taxonomy Team that formed the Phase of Flight Definitions and Usage Notes in October 2002. From the &lt;a href=&quot;http://www.intlaviationstandards.org/apex/f?p=240:1:10686934051912::NO::P1_X:CurrentUsers&quot; rel=&quot;nofollow noreferrer&quot;&gt;CAST/ICAO Common Taxonomy Team&lt;/a&gt; site:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Federal Aviation Administration (FAA)- FAA has officially adopted the aircraft make model series (ACFT-MMS) and phase of flight taxonomies as an agency-wide data standard for its internal systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, the enroute phase of flight is the same (just repeating from the &lt;a href=&quot;http://www.intlaviationstandards.org/Documents/PhaseofFlightDefinitions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;same document&lt;/a&gt;):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Instrument Flight Rules (IFR): From completion of Initial Climb through cruise altitude and completion of controlled descent to the Initial Approach Fix (IAF).&lt;/p&gt;&#xA;&lt;p&gt;Visual Flight Rules (VFR): From completion of Initial Climb through cruise and controlled descent to the VFR pattern altitude or 1,000 feet above runway elevation, whichever comes first.&lt;/p&gt;&#xA;&lt;p&gt;This phase of flight includes the following subphases:&lt;/p&gt;&#xA;&lt;p&gt;• Climb to Cruise: IFR: From completion of Initial Climb to arrival at initial assigned cruise altitude. VFR: From completion of Initial Climb to initial cruise altitude.&lt;/p&gt;&#xA;&lt;p&gt;• Cruise: Any level flight segment after arrival at initial cruise altitude until the start of descent to the destination.&lt;/p&gt;&#xA;&lt;p&gt;• Change of Cruise Level: Any climb or descent during cruise after the initial climb to cruise, but before descent to the destination.&lt;/p&gt;&#xA;&lt;p&gt;• Descent: IFR: Descent from cruise to either Initial Approach Fix (IAF) or VFR pattern entry. VFR: Descent from cruise to the VFR pattern entry or 1,000 feet above the runway elevation, whichever comes first.&lt;/p&gt;&#xA;&lt;p&gt;• Holding: Execution of a predetermined maneuver (usually an oval racetrack pattern) which keeps the aircraft within a specified airspace while awaiting further clearance. Descent during holding is also covered in this subphase.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-06T00:10:34.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23440" PostTypeId="2" ParentId="23431" CreationDate="2015-12-06T00:14:24.517" Score="17" Body="&lt;p&gt;An airline crew has two primary goals: safety and legality.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even for large airplanes, one person's change of position can put the takeoff CG outside legal limits and/or safe limits.  Either situation is unacceptable.  In order to calculate the CG, the passengers have to stay in a particular spot so the cabin crew can report the passengers' locations to the flight crew, who then calculates the takeoff CG.  The passengers should stay in the same seat from the beginning of this process until after takeoff and initial climb, and preferably throughout the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I fly a CRJ-900, for example.  This is a 70+ passenger, 85,000lb regional jet.  Its not uncommon for us to ask the cabin crew to move one passenger from front to back in order for the calculated balance point (CG) to be in the correct envelope for takeoff.  If that one person moved back after the calculation, the CG would be just outside the CG envelope, and we would technically be illegal to take off, which is unacceptable.  Each flight prepares a manifest of passengers and calculated weight and CG which is kept on file and audited by aviation authorities like the FAA, and the recorded values must show a legal loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CG envelope includes some safety margin, so being a tiny amount (0.1% MAC for example) out would likely not make the aircraft uncontrollable; but it is possible, especially if several people are moving, and its an unknown situation that no professional flight crew is going to permit.  Even on a &quot;large&quot; plane, one person's location has such an effect on CG that if someone in the front walks to the rear in flight, it will have an effect on the trim of the plane and either the pilot or the autopilot will correct for this using trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, its likely the crew was serious and honest when they asked you to stay in one location for balance purposes.  It could have been for safety or legal reasons, and both are required to be maintained by the crew at all times.&lt;/p&gt;&#xA;" OwnerUserId="7365" LastActivityDate="2015-12-06T00:14:24.517" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23441" PostTypeId="2" ParentId="23438" CreationDate="2015-12-06T00:23:26.107" Score="3" Body="&lt;p&gt;All jets require a type rating. Therefore you don't need the complex endorsement directly (other than needing it likely for your commercial checkride, which requires a complex aircraft). The historical training progression is: simple prop, complex single engine prop (requiring the complex endorsement), high performance (200 hp+, though this one is sometimes not gotten), light multi-engine props, and then finally moving into heavier turboprops and then jets which require type ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, my answer is FAA specific, and other agencies might have different rules/interpretations for this issue.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="1961" LastEditDate="2015-12-06T09:06:51.117" LastActivityDate="2015-12-06T09:06:51.117" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23442" PostTypeId="2" ParentId="23437" CreationDate="2015-12-06T04:17:51.327" Score="16" Body="&lt;p&gt;First, if you fly privately without a license can you avoid trouble with the FAA? Yes, if you don't attract attention to yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's essentially the same as driving a car without a license or insurance: it happens because some people just don't see why they should have to get a license, and it's possible because no one regularly checks every car and every driver. Anecdotally, there are plenty of pilot stories about unlicensed pilots in rural, remote areas who fly out of private strips or small, uncontrolled airports. Alaska in particular is notorious: I've heard the 'joke' several times that the FAA used to have the goal of getting at least 50% of Alaskan pilots certificated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, if you do get caught by the FAA or by law enforcement, what happens? As you said, the FAA can revoke your certificate but state or federal officials can go after you with criminal charges. This is from &lt;a href=&quot;http://www.justice.gov/usao-wdnc/pr/aiport-operator-charged-flying-airplane-without-proper-lincense-and-lying-federal&quot;&gt;the criminal indictment&lt;/a&gt; of someone who was accused of lying about his pilot's and mechanic's certificates:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At sentencing he faces a maximum of five years in prison and a&#xA;  \$250,000 fine for each of the two criminal counts of making false&#xA;  statements to the FAA, and a maximum of three years in prison and a&#xA;  \$250,000 fine for each of the three counts of flying without proper&#xA;  authorization.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I couldn't find out what happened with that case, though, so I don't know if he was found guilty or not and penalties - if any - he really faced. @mins found &lt;a href=&quot;https://www.oig.dot.gov/library-item/28930&quot;&gt;another example&lt;/a&gt; that did result in a prison sentence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, there is one legal way to fly in the US without a license: fly an ultralight under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=61e88652fa9a94ee03e3572a55499d82&amp;amp;node=pt14.2.103&amp;amp;rgn=div5&quot;&gt;part 103&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-06T04:17:51.327" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23443" PostTypeId="1" CreationDate="2015-12-06T05:34:30.713" Score="1" ViewCount="820" Body="&lt;p&gt;There was a recent new story of a Kuwait Airways pilot that got his license revoked after an investigation into an incident on an international flight where unauthorized persons were allowed on to the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read more about the actual incident &lt;a href=&quot;http://gulfnews.com/news/gulf/kuwait/kuwait-airways-pilot-loses-licence-for-inviting-porn-star-into-cockpit-1.1631938&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can this pilot still obtain another license to fly commercially?&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2015-12-06T06:04:38.113" Title="If a pilot license is revoked by a country's aviation authority, can the pilot still obtain another license?" Tags="&lt;regulations&gt;&lt;airline-pilot&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23444" PostTypeId="2" ParentId="23424" CreationDate="2015-12-06T05:55:58.073" Score="3" Body="&lt;p&gt;In the US the HIPAA rules often provide you with confidentiality but there are several circumstances that allow your doctor to provide info without your consent and being a pilot qualifies. It &lt;em&gt;allows&lt;/em&gt; them to, but only &lt;em&gt;requires&lt;/em&gt; them to in situations where a crime might be involved, i.e. physical abuse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concern would probably not be that your doctor will tell the FAA (although they probably could if they were truly concerned), it would be that you would be required to tell your FAA examiner of any diagnosis. I believe it's a felony not to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's sleep apnea he's concerned about (you said sleep problem, non-narcolepsy - I'm not a doctor so I'm just offering what i know about a very common sleep problem) then there are ways to get a special issuance medical certificate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not a pilot but a driver and I have to have a DOT medical card. The way sleep apnea is usually treated is by CPAP. For the DOT physical, If you are on CPAP you have to bring the machine to your physical so the examiner can check the data and verify that you have been using it (I think 75% of the time but don't quote me on that). I checked and the FAA has &lt;a href=&quot;https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=18156&quot; rel=&quot;nofollow&quot;&gt;similar rules&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I agree with Pondlife that one's health should trump licensing concerns, and nobody should be flying if they are at risk of dozing off. But I definitely understand your friend's situation. I suspected I had apnea but I refused to go to a sleep study because I did not want the diagnosis. What if I couldn't deal with CPAP? My dad was on CPAP for 30 years but he rarely used it because it was too uncomfortable. Then I'd be &lt;em&gt;forced&lt;/em&gt; to use it to keep my job. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fortunately my situation resolved itself (I don't have apnea) but I understand why he's reticent to mention it to his doctor. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-12-06T05:55:58.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23445" PostTypeId="2" ParentId="23443" CreationDate="2015-12-06T05:59:19.690" Score="2" Body="&lt;p&gt;It depends on the regulations in force. Usually, depending in the reason for revocation, the pilots can apply for recertification after a set period (usually one year) where they have to go through the whole process again. For example, according to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.13&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.13&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) Application during suspension or revocation.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Unless otherwise authorized by the Administrator, a person whose pilot, flight instructor, or ground instructor certificate has been revoked may not apply for any certificate, rating, or authorization for 1 year after the date of revocation. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It appears that these pilots too, can get another certificate after an year. According to &lt;a href=&quot;https://www.dgca.gov.kw/en/safety-systems/aviation-dept-and-systems/aviation-safety-department/kcasr&quot; rel=&quot;nofollow&quot;&gt;Kuwait Civil Aviation Safety Regulations, Part 1&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.2.11 Surrender, Suspension or Revocation of License, Certificate or&#xA;  Authority&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;3) Unless the order of revocation provides otherwise, a person whose&#xA;  License/ authority /certificate is revoked, may not apply for any&#xA;  License, certificate or authority before the elapse of one year from&#xA;  the date of revocation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-06T06:04:38.113" LastActivityDate="2015-12-06T06:04:38.113" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23446" PostTypeId="2" ParentId="23431" CreationDate="2015-12-06T06:33:01.350" Score="5" Body="&lt;p&gt;From &lt;a href=&quot;https://reports.nlr.nl/xmlui/handle/10921/402&quot; rel=&quot;nofollow noreferrer&quot;&gt;NLR Analysis of aircraft weight and balance related safety occurrences&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Example 1: Overweight take off B727-200 (PP-LBY), Fly Lineas Aereas,&#xA;Quito airport, Ecuador, 01/05/1996. (source: NLR Air Safety Database)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;During take off from runway 35 at Quito, the crew felt that the&#xA;aircraft was not accelerating quickly enough and was not reaching the&#xA;calculated V speeds. Therefore the crew elected to abort the take off&#xA;at 120 knots (V1=143 knots). The runway was wet and the available&#xA;runway length left to stop the aircraft was only 900 meters (3000&#xA;ft.). The aircraft could not be stopped on the runway and overran the&#xA;end. It came to rest some 130 meters from the runway end after having&#xA;struck an ILS antenna and the airport perimeter fence. The maximum&#xA;take off weight was exceeded by some 9,729 kg (+16%) for the&#xA;conditions at Quito. It was determined after the accident that the&#xA;crew had not calculated the weight and balance for the flight. Instead&#xA;they had used the load sheet from a previous flight.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Example 2: Exceedance of aft centre of gravity limit during landing&#xA;F27-600 (G-CHNL), Channel Express (Air Services) Ltd, Guernsey,&#xA;Channel Islands, United Kingdom, 12/01/1999. (Source: AAIB UK)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The&#xA;aircraft was destroyed when it went out of control and crashed during&#xA;the final stage of the approach to Runway 27 at Guernsey. After an&#xA;uneventful flight, during the final stage of the approach, the pilot&#xA;called for 'flaps forty' (the full down position) and the flaps were&#xA;extended to this position. Moments after the wing flaps were lowered&#xA;to their fully down position, the nose of the aircraft rose and the&#xA;crew were unable to prevent it rising further. The nose continued to&#xA;rise until the aircraft's pitch attitude was near vertical. Although&#xA;the crew applied nose down pitch trim and high&#xA;engine power, the aircraft lost flying speed, stalled and entered an&#xA;incipient spin. Returning the flaps to the intermediate approach&#xA;setting of 26.5° and raising the landing gear did not restore&#xA;controllability. It descended in a shallow nose down pitch attitude&#xA;with little forward speed and crashed at the rear of a private house,&#xA;striking the house with its port wing. Both the house and the aircraft&#xA;caught fire. The two pilots were killed but the sole occupant of the&#xA;house escaped without physical injury. The aircraft was operating a&#xA;flight from Luton with a cargo of three tonnes of newspapers. Prior to&#xA;departure, the cargo had to be hand loaded. However, neither the load&#xA;team leader nor the dispatcher had loaded an F.27 before nor did they&#xA;have a load plan to assist them. They therefore asked the captain how&#xA;to proceed. The captain reportedly replied along the lines 'from the&#xA;back' or 'put it all in the rear.' Subsequently the loading team&#xA;stacked the papers in even piles, some 2ft. 6in. high, across the&#xA;width of the cabin, working from a point in line with the rear doors&#xA;forward. The papers eventually extended forward for an estimated&#xA;distance of between one quarter and one third of the length of the&#xA;cabin. As a result, the aircraft's centre of gravity ended up&#xA;significantly aft of its approved limit and it became uncontrollable&#xA;once full flap had been selected for landing. The crew of the aircraft&#xA;appeared to have taken only limited interest in the loading. The&#xA;comments made by the investigators was that 'this behaviour contrasts&#xA;strongly with the commander's careful manner and thorough attitude&#xA;whilst actually flying' and suggests that 'either he was not aware of&#xA;the importance of load positioning and restraint or that he was not&#xA;sure how to direct and supervise the loading operation.' No official&#xA;'load planning' tables were provided for the flight crew to use. Crews&#xA;were apparently expected to devise a load plan by 'trial and error'&#xA;using the balance chart on the load sheet. The investigators commented&#xA;that this could be time consuming and not as error resistant as&#xA;pre-planned tables. Additionally, it was noted that loading procedures&#xA;were not a structured element of the command training syllabus and&#xA;there was therefore an element of chance that new commanders might not&#xA;be properly trained in this area. This accident was provoked by&#xA;operating the aircraft outside the cleared load and balance&#xA;limitations. This error went undetected because nobody ensured that&#xA;the cargo distribution in the aircraft was the same as that shown on&#xA;the load and balance sheet.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Example 3: Exceedance of forward centre of gravity limit during take&#xA;off Convair 880, N5865, Air Trine, Miami International Airport, USA,&#xA;16/12/1976 (source: NLR Air Safety Database/NTSB)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The Convair 880 was&#xA;loaded with a cargo of cows. Following an apparently normal take off&#xA;run on Runway 09L reaching the rotation speed, the aircraft would not&#xA;rotate despite repeated efforts by the crew including re-trimming the&#xA;aircraft to the 'full nose-up' position. The pilot&#xA;subsequently elected to abort the take off but was unable to bring the&#xA;aircraft to a stop before the end of the runway. After leaving the&#xA;runway, the aircraft passed over an area of soft ground, where its&#xA;nose undercarriage collapsed, before falling into a wide drainage&#xA;canal. The investigation determined that on take off the aircraft's&#xA;centre of gravity was some 2.2% of the mean aerodynamic chord in front&#xA;of the maximum forward limit, due to the way the aircraft had been&#xA;loaded, and that the crew's weight and balance calculations bore no&#xA;resemblance to the way the weight was actually distributed.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Example 4: Overweight take off with an exceedance of forward centre of&#xA;gravity limit B727-200, 3X-GDO, Union des Transports Africains,&#xA;Cotonou, Bénin, 25-12-2003 (source: BEA Bureau d'Enquêtes et&#xA;d'Analyses pour la Sécurité de l'Aviation Civile, report translation&#xA;3x-o031225a)&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;On December 25th, 2003, a Boeing 727 operated by the&#xA;Union des Transports Africains (UTA) crashed during take off from&#xA;Cotonou. There were at least 160 people on board and only 22 survived.&#xA;Passenger boarding and baggage loading was carried out in great&#xA;confusion. For flight preparation, incomplete information on the&#xA;loading was provided to the Captain. He had determined the&#xA;configuration for take off on the basis of this information. The&#xA;investigation showed that, after the brakes were released, the&#xA;aircraft accelerated up to rotation speed. As the forward hold had&#xA;been filled, the aircraft had a significant forward centre of gravity&#xA;that the crew had not compensated for with the stabiliser because they&#xA;had not been informed of the loading of this hold. The pilot's nose-up&#xA;input thus did not have an immediate effect and it took seven seconds&#xA;for the aircraft to leave the ground, with a very low slope angle. The&#xA;aircraft hit a building located on the extended runway centreline,&#xA;crashed onto the beach and ended up in the ocean. The investigation&#xA;also showed that, without the uncompensated forward centre of gravity,&#xA;the aircraft would have taken off despite its excess weight. The&#xA;investigation concluded that the accident was due to the crew's&#xA;difficulties in performing the rotation with an overloaded aircraft&#xA;with a forward centre of gravity that they were unaware of.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12558" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-12-23T20:48:06.123" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="23447" PostTypeId="2" ParentId="23412" CreationDate="2015-12-06T10:28:03.267" Score="1" Body="&lt;p&gt;Don't compare military troops transports and airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Goals are not the same, inducing requirements and means differ. Not to say that soldiers can be packed as cargo, but military transports are supposed to mobilize huge amount of troops with their equipements on the battle field in no time, and soldiers know that and are prepared for critical scenarios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If troops were to ask for same treatment as civilian passengers, it would raise the following issues :&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you'll need wider seats and pitching, in a more &quot;civilian&quot; configuration, meaning much less &quot;passengers&quot; per aircraft, and much less troops carried per flight.&lt;/li&gt;&#xA;&lt;li&gt;more planes to carry troops, more targets for the enemy. You don't always fly in ally airspace.&lt;/li&gt;&#xA;&lt;li&gt;This increases aircraft operations, which kills one military strategy called sneak attack. Predictible operations are a strategy error.&lt;/li&gt;&#xA;&lt;li&gt;More flights means more time to be handled, meaning delays. Time is always an issue in military operations, both upon mobilizing, and returning back home with waiting families.&lt;/li&gt;&#xA;&lt;li&gt;if you want to have both nice seatings and paradrop capabilities, you'll have to make room for the drop process which also removes more seatings.&lt;/li&gt;&#xA;&lt;li&gt;optionally, you'll also need flight attendants to serve meals.&lt;/li&gt;&#xA;&lt;li&gt;All that induce more costs (planes, civilian plane equipements like expensive seats, galleys and trolleys, etc.) which increases military budget.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It seems on a military point of view, having civilian-like things doesn't bring advantages, only issues. So that's how it is.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If troop transport concepts were to be used on civilian side (airliners), I don't think you and me would agree (assuming we're not soldiers)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;we paid for the flight, soldiers are paid to fight and signed with all that comes with that duty including death.&lt;/li&gt;&#xA;&lt;li&gt;we just want to have a good flight from departure to destination in the safest possible way, in a comfortable seat, with meals and entertainment.&lt;/li&gt;&#xA;&lt;li&gt;if airliners were that &quot;loaded&quot;, we'll have less flights per route, meaning less schedules. If the schedule doesn't comply with your plans, you'll have to wait for the next available flight.&lt;/li&gt;&#xA;&lt;li&gt;serving meals would be much more complicated; perhaps it's better to have lunch before flight, not inflight. Ask a flight attendant's opinion about serving meals and pillows in that condition...&lt;/li&gt;&#xA;&lt;li&gt;lavatories on the other hand would always be mandatory, don't worry. But we should be trained to walk through, step over sleeping passengers legs...&lt;/li&gt;&#xA;&lt;li&gt;we would have to sign a waiver about the sideward facing neck (head, and shoulder) injury(es) in case of critical stop.&lt;/li&gt;&#xA;&lt;li&gt;we would also have to sign a waiver about &quot;flying bags&quot; upon turbulences. It's highly unlikely you would be able to put everything in luggage bins with that much passengers in a Boeing 737.&lt;/li&gt;&#xA;&lt;li&gt;The only advantage would be a substantial reduction in travel cost (on our side)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Worth it ? I, personally say NO !&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;By the way, mass evacuations are a huge step beyound your posted picture. ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I inverted scenarios by suggesting why military personnel wouldn't have the same treatment as civilian travelers on purpose : you're comparing two very different situations that doesn't have the same priorities, goals and safety concerns. That means what matters, what is more efficient, what costs less in a case are not the same for the other. The target audience is different. One is going to fight at war, the other is on vacation/family/friends visit, business travel or starting a new life. That means it's not only about safety concerns.&lt;/p&gt;&#xA;" OwnerUserId="3879" LastActivityDate="2015-12-06T10:28:03.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23449" PostTypeId="1" AcceptedAnswerId="23450" CreationDate="2015-12-06T12:32:51.780" Score="6" ViewCount="10029" Body="&lt;p&gt;I often hear the word &quot;flameout&quot;. What is this and how does it occur?&lt;/p&gt;&#xA;" OwnerUserId="9544" LastActivityDate="2015-12-06T15:14:44.543" Title="What is a flameout and how does it occur?" Tags="&lt;jet-engine&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23450" PostTypeId="2" ParentId="23449" CreationDate="2015-12-06T13:15:46.200" Score="9" Body="&lt;p&gt;Flameout basically means that the flame in the combustion chamber has been extinguished. A jet engine compresses air, then adds fuel and ignites it. So, it needs three things to function correctly- fuel, air (oxygen), and the heat to make them burn. &lt;a href=&quot;http://www.airspacemag.com/flight-today/flameout-9043856/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;Removing any of the three can cause a flameout&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can happen for a number of reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;fuel starvation- &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;noreferrer&quot;&gt;Air Canada Flight 143&lt;/a&gt; suffered flameout (due to wrong amount of fuel being put) and had to be landed like a glider.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compressor stall (or surge)- The disruption of airflow due to compressor stall can cause an engine flameout.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ingestion of foreign objects - &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_9&quot; rel=&quot;noreferrer&quot;&gt;British Airways Flight 9&lt;/a&gt; suffered flameouts in all four engines due to ingestion of volcanic ash&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Firing of armament- Early in its service A-10 Warthog suffered flameouts due to the engines ingesting the gassed generated while firing the GAU-8 Avenger.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Early jet engines (like the Jumo 004B) had &lt;a href=&quot;http://www.stormbirds.com/project/technical/technical_3.htm&quot; rel=&quot;noreferrer&quot;&gt;high rates of flameout&lt;/a&gt;; however, modern jet engine flame outs are very rare, at the rate of about one every 100,000 non military flights. In most cases of flameout, the &lt;a href=&quot;http://www.wsj.com/articles/SB120753185285993925&quot; rel=&quot;noreferrer&quot;&gt;engines are restarted&lt;/a&gt; for resumption of flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airspacemag.com/flight-today/flameout-9043856/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;Airspace magazine&lt;/a&gt; mentions a case where flameout happened because a F-100 ingested fuel (during aerial refueling); however, such occurrences are quite rare.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-06T15:14:44.543" LastActivityDate="2015-12-06T15:14:44.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23453" PostTypeId="2" ParentId="23412" CreationDate="2015-12-06T18:23:51.427" Score="5" Body="&lt;p&gt;I believe the apparent lack of space or the discomfort is a red-herring. That's simply not the case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The passengers don't seem to be tighter packed than in a Ryanair flight actually. And I also don't believe that the sidewards configuration is motivated by this rationale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is a Boeing C-17. It does not have a civilian version, so direct comparison of seat arrangements is not possible. Its inner space, however, is actually 18 feet (5.49 m) wide for 7 passengers and two ailes. So, it appears that the latter is less generous with its 737-800 &amp;lt; 12 feet wide with a single aisle, for 6 passengers (each getting 17.2).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing C-17 is a multi-purpose military aircraft, designed to be adapted to different tasks (hence the sidewards seat).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is meant for being used for medical evacuation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/9a/Medevac_mission%2C_Balad_Air_Base%2C_Iraq.jpg&quot; alt=&quot;example&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, for transporting a howitzer:&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Pzh-2000_inside_of_a_C-17.jpg/800px-Pzh-2000_inside_of_a_C-17.jpg&quot; alt=&quot;example2&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, for transporting paratroopers: &#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/82nd_Airborne_paratroopers_in_a_C-17.jpg/1024px-82nd_Airborne_paratroopers_in_a_C-17.jpg&quot; alt=&quot;example3&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="12566" LastEditorUserId="12566" LastEditDate="2015-12-06T18:40:08.440" LastActivityDate="2015-12-06T18:40:08.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23454" PostTypeId="1" CreationDate="2015-12-06T19:17:01.700" Score="6" ViewCount="2245" Body="&lt;p&gt;When someone operates an unregistered vehicle on public roads we know how they are caught: Police routinely pull people over, and they always check registration of vehicles.  In fact, police will frequently &quot;run tags&quot; without even stopping cars.  They have a realtime connection to a nationwide registry that can report the details of the tagged car and whether a tag is expired or stolen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/23437/11671&quot;&gt;Apparently there are a good number of fines and prosecutions for operation of unregistered aircraft&lt;/a&gt;.  And at least some are reported by ATC.  I'm going to assume that nobody is foolish enough to file a flight plan listing an unregistered aircraft ID.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how does ATC check aircraft registration?  Do they have live access to the registry?  When someone calls an ID over the radio are there controllers that routinely check the ID's registration?  Is it illegal to make up an ID for radio interaction with ATC?  Are there people that visually watch for tail numbers and discrepancies with radio calls?&lt;/p&gt;&#xA;" OwnerUserId="11671" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2021-02-23T05:14:33.857" Title="How are aircraft identified as unregistered?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;usa&gt;&lt;aircraft-registration&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23455" PostTypeId="2" ParentId="23454" CreationDate="2015-12-06T19:37:22.257" Score="7" Body="&lt;p&gt;Aircraft don't have to be actually flying for people to notice something fishy going on. In particular, there are always people hanging about at airports keeping an eye on everything going on. Furthermore (at least in the US), aircraft registration details are a matter of public record and can be easily looked up online.&lt;/p&gt;&#xA;&lt;p&gt;For example, here is the registration detail page for John Travolta's private Boeing 707: &lt;a href=&quot;https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=N707JT&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=N707JT&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As you can see it contains complete registration details including type, validity status, expiration dates, owner name and address, and airworthiness status.&lt;/p&gt;&#xA;" OwnerUserId="675" LastEditorUserId="3427" LastEditDate="2021-02-23T05:14:33.857" LastActivityDate="2021-02-23T05:14:33.857" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23456" PostTypeId="2" ParentId="23454" CreationDate="2015-12-06T22:05:35.800" Score="5" Body="&lt;p&gt;&lt;strong&gt;So how does ATC check aircraft registration?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They don't, that isn't their job. The only time that anyone will ask to see your registration in normal circumstances is during a &lt;a href=&quot;https://aviation.stackexchange.com/q/634/62&quot;&gt;ramp check&lt;/a&gt;, and those are done by FAA inspectors. There are probably some other 'routine' checks, like a checkride examiner verifying it as part of the checkride or your insurance company asking for a copy. I suppose it's also possible that your state might want to see it for some tax-related reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do they have live access to the registry?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea, but as &lt;a href=&quot;https://aviation.stackexchange.com/a/23455/62&quot;&gt;Greg pointed out&lt;/a&gt; the registry is open to anyone with an internet connection so it's at least possible that they do. But I don't really see how any of the registration information would be relevant or useful to ATC operations anyway. One possible exception could be search and rescue: I guess the registration information might be useful for contacting the aircraft owner if the aircraft is missing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When someone calls an ID over the radio are there controllers that routinely check the ID's registration?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, I have no idea, but I can't think why ATC would want or need to check it and I couldn't find anything in the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC orders&lt;/a&gt; about checking it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is it illegal to make up an ID for radio interaction with ATC?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I couldn't find any specific regulation about that, but if the FAA wants to enforce it then I'm sure they'll find something. They could always fall back on &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.13&lt;/a&gt; and claim that by lying to ATC you're displaying reckless behavior. And if the government really wants to get serious with you then they could charge you under &lt;a href=&quot;https://www.law.cornell.edu/uscode/text/18/1001&quot; rel=&quot;nofollow noreferrer&quot;&gt;18 USC 1001&lt;/a&gt;: lying to a federal government agent is a criminal offense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are there people that visually watch for tail numbers and discrepancies with radio calls?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, they're called planespotters :-) I'm only half-joking: some people are obsessive about things like that, and it wouldn't surprise me at all if someone out there likes to look up the owners of aircraft he hears on the radio.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-06T22:05:35.800" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="23457" PostTypeId="1" AcceptedAnswerId="23458" CreationDate="2015-12-07T02:06:38.637" Score="6" ViewCount="4160" Body="&lt;p&gt;The beginning scenes of the movie &quot;San Andreas&quot; partly take place in a rescue helicopter. One of the panel gauges read &quot;GAS PROD&quot; above it. I googled it but didn't find much. Can someone explain what it does, and how it measures what's it measures? Thanks! &lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="167" LastEditDate="2015-12-07T05:06:44.770" LastActivityDate="2018-11-11T22:24:10.263" Title="What does a helicopter &quot;gas prod&quot; gauge measure?" Tags="&lt;helicopter&gt;&lt;flight-instruments&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23458" PostTypeId="2" ParentId="23457" CreationDate="2015-12-07T03:08:48.003" Score="8" Body="&lt;p&gt;The instrument shows the gas generator rpm in the engine. It think you are referring to this scene (screenshot from youtube):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GpVXF.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GpVXF.png&quot; alt=&quot;Gas Prod&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The Bell 412 in the movie uses a pair of Pratt &amp;amp; Whitney Canada PT6T-3BE Twin-Pac turboshafts, which are free turbine engines. The turboshafts used in helicopters consist of,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Compressor&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Combustion chamber&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;turbine&lt;/p&gt;&#xA;&lt;p&gt;and other components.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The gas producer (from which 'GAS PROD' came) forms part of the turbine. The gas generator forms the first stage that runs the compressor and makes the engine self sustaining. It also runs the oil and fuel pumps. As it is a free turbine, the gas generator stage is not mechanically connected to the next (power turbine) stage. From &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=105&amp;amp;sID=460&amp;amp;preview=true&quot; rel=&quot;noreferrer&quot;&gt;faasafety.gov&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The turbine section consists of a series of turbine wheels that are used to drive the compressor section and the rotor system. The first stage, which is usually referred to as the gas producer or N1 may consist of one or more turbine wheels. This stage drives the components necessary to complete the turbine cycle making the engine self-sustaining. Common components driven by the N1 stage are the compressor, oil pump, and fuel pump. The second stage, which may also consist of one or more wheels, is dedicated to driving the main rotor system and accessories from the engine gearbox. This is referred to as the power turbine (N2 or Nr).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In some cases, NG is used in place of N1. The gas generator speed is measured in the PT6 engines using a tachometer-generator mounted  on the engine.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.google.co.in/url?sa=i&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=images&amp;amp;cd=&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwiqpveG4sjJAhXYBo4KHS60BMAQ5TUICQ&amp;amp;url=http%3A%2F%2Fwww.unitedturbine.com%2Fpdfs%2FPT6%2520Training%2520Manual.pdf&amp;amp;bvm=bv.108538919,d.d24&amp;amp;psig=AFQjCNGUEuxD7r3NCkaSycKH0iJwQ38_lA&amp;amp;ust=1449543215825815&quot; rel=&quot;noreferrer&quot;&gt;United turbine training Manual&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The tachometer-generator produces an electric current which is used in conjunction with a tachometer to indicate gas generator RPM. The tachometer-generator drive and mount pad are located at the 5 o’clock position on the accessory gearbox and is driven form the internal scavenge pump.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-07T05:53:48.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23459" PostTypeId="1" AcceptedAnswerId="23463" CreationDate="2015-12-07T03:46:12.687" Score="18" ViewCount="33957" Body="&lt;p&gt;Consider a hypothetical flight plan from Redstone to Cullman to Gadsden and back to Redstone. This flight would have legs in order of 26, 42, and 52 nautical miles.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0FOuD.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0FOuD.png&quot; alt=&quot;KHUA KCMD KGAD KHUA on SkyVector&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;14 CFR 61.1 provides&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Cross-country time&lt;/em&gt; means—&lt;/p&gt;&#xA;&lt;p&gt;…&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(ii)&lt;/strong&gt; For the purpose of meeting the aeronautical experience requirements (except for a rotorcraft category rating), for a private pilot certificate (except for a powered parachute category rating), a commercial pilot certificate, or an instrument rating, or for the purpose of exercising recreational pilot privileges (except in a rotorcraft) under §61.101(c), time acquired during a flight—&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(A)&lt;/strong&gt; Conducted in an appropriate aircraft;&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(B)&lt;/strong&gt; That includes a point of landing that was at least a straight-line distance of more than 50 nautical miles from the original point of departure; and&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(C)&lt;/strong&gt; That involves the use of dead reckoning, pilotage, electronic navigation aids, radio aids, or other navigation systems to navigate to the landing point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The original point of departure is Redstone Army Airfield, and Northeast Alabama Regional is farther than 50 nautical miles away. Would the entire flight count toward the cross-country experience requirements for a private pilot certificate, commercial pilot certificate, or instrument rating? Must the pilot fly the 50+ nm leg first?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-08-14T15:06:05.493" Title="FAA: May I log as cross-country a flight with two or more short legs?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23460" PostTypeId="1" AcceptedAnswerId="23461" CreationDate="2015-12-07T03:49:00.133" Score="42" ViewCount="10404" Body="&lt;p&gt;I was reading some military fiction and saw a comment that army airborne operations were required to repack all parachutes every ninety days, allowing parachutes that were due to be repacked soon to be cheaply used for training. This got me thinking: do parachutes need to be repacked on a schedule? Is this uniform across all types of parachutes and use cases? (are there differences between military and civilian requirements?) How long is the repack cycle? Why is scheduled repacking needed?&lt;/p&gt;&#xA;" OwnerUserId="2910" LastActivityDate="2015-12-12T16:29:59.380" Title="Do unused parachutes need to be repacked? If so how often and why?" Tags="&lt;parachute&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23461" PostTypeId="2" ParentId="23460" CreationDate="2015-12-07T04:34:46.173" Score="42" Body="&lt;p&gt;Yes, parachutes need to be repacked regularly. The length of the interval depends on the material of the parachute and is between 60 and 180 days. Every parachute should have a small pocket with a piece of paper which lists the most recent repack date and the name of the packer (who needs to comply with &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=8f10e5643aa978d2c6fa5789894ead0c&amp;amp;mc=true&amp;amp;n=pt14.2.65&amp;amp;r=PART&amp;amp;ty=HTML#sp14.2.65.f&quot;&gt;FAR part 65, subpart F&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8f10e5643aa978d2c6fa5789894ead0c&amp;amp;mc=true&amp;amp;node=se14.2.91_1307&amp;amp;rgn=div8&quot;&gt;FAA part 91.307&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No pilot of a civil aircraft may allow a parachute that is&#xA;  available for emergency use to be carried in that aircraft unless it&#xA;  is an approved type and has been packed by a certificated and&#xA;  appropriately rated parachute rigger—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Within the preceding 180 days, if its canopy, shrouds, and harness&#xA;  are composed exclusively of nylon, rayon, or other similar synthetic&#xA;  fiber or materials that are substantially resistant to damage from&#xA;  mold, mildew, or other fungi and other rotting agents propagated in a&#xA;  moist environment; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Within the preceding 60 days, if any part of the parachute is&#xA;  composed of silk, pongee, or other natural fiber or materials not&#xA;  specified in paragraph (a)(1) of this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The reason should be clear from the regulation: If moisture is present, the growth of mold may prevent the parachute from unfolding easily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the &lt;a href=&quot;https://en.wikipedia.org/wiki/T-10_parachute&quot;&gt;T-10D parachute&lt;/a&gt;, which is the standard US Army parachute for airborne assault operations, the repack period is 120 days.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-07T04:47:48.480" LastActivityDate="2015-12-07T04:47:48.480" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="23462" PostTypeId="2" ParentId="6263" CreationDate="2015-12-07T04:50:08.300" Score="0" Body="&lt;p&gt;The CF-101 Voodoo had a landing speed of 175 kts plus fuel weight over 3000 lbs over which it was 5 kts per 1000 lbs of fuel.  BTW crash landed one at 195 kts in Feb 82.&lt;/p&gt;&#xA;" OwnerUserId="12568" LastActivityDate="2015-12-07T04:50:08.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23463" PostTypeId="2" ParentId="23459" CreationDate="2015-12-07T04:55:55.690" Score="20" Body="&lt;p&gt;From a &lt;a href=&quot;https://web.archive.org/web/20170209065346/https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2008/sisk%20-%20(2008)%20legal%20interpretation.pdf&quot; rel=&quot;noreferrer&quot;&gt;2008 FAA interpretation sent to E. Thomas Sisk&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;… cross-country flight time is defined as time acquired during a flight that includes a point of landing that is at least a straight-line distance of more than 50 nm from the original point of departure, not the original point of any flight leg. There is no requirement that any specific leg must be 50 nm. Moreover, a cross-country flight may include several legs that are less than a straight-line distance of more than 50 nm from the original point of departure. Nevertheless, at least one leg of the cross-country flight, however long by itself, must include a point of landing that is at least a straight-line distance of more than 50 nm from the original point of departure (i.e. of the flight, not of that particular leg).&lt;/p&gt;&#xA;&lt;p&gt;Given the above analysis, the answer is each cross-county flight used to meet the aeronautical experience requirements under 14 CFR §61.1 (b)(3) must include one leg that includes a landing that is at least a straight-line distance of more than 50 nm from the original point of departure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From the above, it is pretty clear that the order of flying does not matter and you can log the whole flight.&#xA;Also, see &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/1998/october/flight-training-magazine/no-dumb-questions&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; AOPA response.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-08-12T21:41:22.257" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23464" PostTypeId="1" CreationDate="2015-12-07T07:49:03.633" Score="4" ViewCount="642" Body="&lt;p&gt;I have noticed that at Dar es Salaam International (HTDA, Tanzania, Africa) all major airlines (namely KLM, Swiss, Emirates, Turkish) schedule their departures mostly at night starting from 10:00 PM local time onwards. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides the fact that they have to match their flights with ongoing connections, I was wondering if they do this because they fly here with big aircraft (A330-300, B777, B737-900ER) and the airport, even though being at sea level, has very high day temperatures throughout the year (30C and higher).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe this helps during takeoff, which in hot conditions could be risky, especially if fully laden?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-12-07T09:09:24.940" Title="Do airlines schedule departures based on average environmental conditions of departing airport?" Tags="&lt;airline-operations&gt;&lt;flight-schedules&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23465" PostTypeId="2" ParentId="23464" CreationDate="2015-12-07T08:19:09.537" Score="6" Body="&lt;p&gt;In general, high temperatures affect the performance of the aircraft in two major ways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;As the density is lower at higher temperature, the thrust produced by the engine is reduced.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The lift produced is reduced as lift is proportional to the density.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Due to these reasons, an aircraft operating in hot condition will have to either reduce weight for taking of from a fixed runway length or increase the takeoff run for taking off with the same weight. Also the climb performance will be affected at high temperatures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, the airlines &lt;em&gt;could've&lt;/em&gt; schedule operations in conditions when the temperature is less if they believe that takeoff weight is critical for example, in long range fights or where a set number of passengers is necessary for economical operation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this problem is mostly critical in case of '&lt;a href=&quot;https://en.wikipedia.org/wiki/Hot_and_high#Hot_and_high_airports&quot;&gt;hot and high&lt;/a&gt;' airports. In this case, this is most probably for facilitating the arrival of passengers in destinations in the morning. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the SWISS 296 leaves Dar Es Salaam at 11:20 PM (its connecting flight lands only at 1005 PM) and reaches Zurich at 06:16 CET. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-07T09:09:24.940" LastActivityDate="2015-12-07T09:09:24.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23466" PostTypeId="2" ParentId="23464" CreationDate="2015-12-07T08:21:50.740" Score="6" Body="&lt;p&gt;My guess would be this has more to do with logistical reasons than technical limitations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It likely has something to do with airline schedules in European / North American airports where there can often be a night-time curfew in place at airports due to noise concerns etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. I remember Frankfurt till recently at least didn't allow scheduled international landings before 05:00.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ENu99.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ENu99.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ergo, you need to make sure you take off from  Dar es Salaam etc. at times that will ensure a landing slot at EU that won't infringe on the curfew. Many flights even to non-EU, western destinations from Dar es Salaam likely connect via EU hubs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More details at this link about curfew times at various EU airports:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.zurich-airport.com/the-company/media/current-topics/night-flight-ban&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.zurich-airport.com/the-company/media/current-topics/night-flight-ban&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A part of this can also be the greater (i.e. worse) elasticity of booking response to odd / inconvenient flight times in wealthier markets. i.e. One uses up the best slots for  wealthier intra-EU markets for the most elastic customers &amp;amp; then whatever slots remain go to longer, international routes irrespective of the late night slot that results at the destination non-EU airport. i.e. An airline route scheduling team cares far more to ensure departure / landing times on a Copenhagen-Stuttgart flight remain convenient time slots than to try and keep a  Dar es Salaam departure daytime. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, in the intra-EU markets there's competing modes of travel. e.g. Confronted with an inconvenient 23:00 flight a business traveler might choose a 17:00 train instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a Dar es Salaam to Europe sector there's really not any non-air-flight competition for passengers. So one can afford to keep inconvenient local time departures and still expect no penalty from passengers voting with their feet. Of course, this can only be stretched so far because at some point a competing airline can launch a more conveniently scheduled departure. Or as a second order effect tourist traffic can switch plans to alternative destinations etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, on a lot of Indian subcontinent sectors as well departures to EU were traditionally crowded in the 23:00 to 05:00 time slots. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2015-12-07T08:42:56.483" LastActivityDate="2015-12-07T08:42:56.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23467" PostTypeId="2" ParentId="23379" CreationDate="2015-12-07T09:15:36.690" Score="13" Body="&lt;p&gt;I'm not absolutely sure but I think they are the indicators for the inverted fuel pump. From &lt;a href=&quot;http://www.arcforums.com/forums/air/index.php?showtopic=133297&amp;amp;st=0&quot; rel=&quot;noreferrer&quot;&gt;arcforums&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I finally spoke to a friend of mine who used to fly with the Blue Angels during the 2000/2001 show season. He said the lights on the glare shield were for the inverted pump indicator. The BA fly inverted longer than what is normally permitted for the Hornet so the Blue Angels aircraft are modified with a boost pump mounted to the top of the fuel tank. When they fly an inverted manuver for an extended period that pump is truned on, and while inverted fuel is pumped from the main tank to the feed tank. As fuel in the feed tanks is burned, the light would turns from green to yellow to red. When the light turns red it's time to roll back to a normal flight attitude. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the three sets of lights should be for the tanks on both the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this is the answer because the angle of attack indexers are found to the left of the HUD and look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m5h03.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m5h03.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it appears that they (aoa indexers) are found in carrier aircraft (for e.g. A-4 Skyhawk) as approaches are flown at a specified angle of attack rather than at particular airspeeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that these lights are Blue angel specific mod as I'm not able to find them in any other versions.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-07T17:49:33.240" LastActivityDate="2015-12-07T17:49:33.240" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23468" PostTypeId="1" AcceptedAnswerId="23469" CreationDate="2015-12-07T09:23:21.080" Score="25" ViewCount="3337" Body="&lt;p&gt;I understand ailerons, elevators and rudders can be controlled to a very fine degree, and in precise flight, like formation flying, they can be used for very fine course adjustments to maintain the relative distance from another wingman.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the throttle lever can regulate the thrust in range from near zero to several hundred kilonewtons by pushing it maybe 15cm forward. There's very little fine control to it and especially jet engines are sluggish to react to the changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do pilots precisely fine-tune relative speed when traveling at high airspeed then? Are they using other tools - flaps, airbrakes maybe? Or am I underestimating the precision of the throttle, or missing some other mechanisms?&lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="12341" LastEditDate="2016-09-05T01:39:29.133" LastActivityDate="2016-09-05T05:04:46.370" Title="How does aircraft maintain precise speed, e.g. in formation flying or refueling?" Tags="&lt;flying-in-formation&gt;&lt;throttle&gt;&lt;mid-air-refueling&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23469" PostTypeId="2" ParentId="23468" CreationDate="2015-12-07T09:51:57.170" Score="24" Body="&lt;p&gt;The key in holding the same speed as your wingman or the other aircraft is not to find the &quot;perfect&quot; throttle position, the key is to slightly adjust the throttle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you look at cockpit-videos of those formation pilots (like &lt;a href=&quot;https://www.youtube.com/watch?v=NdZ02-Qenso&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; - move the camera to the throttle, it's a 360-degree video), you can see that they are constantly moving the throttle. They almost never stick the throttle at one position. In that way, they can slightly adjust the speed and stay in formation with the wingman for a long time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While flying in close formation at high speed, it's the same. Little adjustments of the throttle helps the pilot to keep the same speed as the wingman-aircraft. Flaps are not used in high-speed-flying because they can only operate below a maximum speed, otherwise they could get damaged. By using the air-brake, the handling of the aircraft changes, therefore the air-brake is not used very often while flying in formation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;tl;dr:&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Skill&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="9544" LastEditDate="2016-02-03T15:16:13.753" LastActivityDate="2016-02-03T15:16:13.753" CommentCount="18" ContentLicense="CC BY-SA 3.0" />
  <row Id="23470" PostTypeId="1" AcceptedAnswerId="23476" CreationDate="2015-12-07T11:45:49.957" Score="18" ViewCount="2346" Body="&lt;p&gt;It seems in 1950's some countries investigated production of helicopters powered by ramjet engines on rotor tips - examples include American &lt;a href=&quot;https://en.wikipedia.org/wiki/Hiller_YH-32_Hornet&quot;&gt;Hiller YH-32 Hornet&lt;/a&gt; or Polish &lt;a href=&quot;http://www.muzeumlotnictwa.pl/zbiory_sz.php?ido=72&amp;amp;w=a&quot;&gt;JK-1 Trzmiel&lt;/a&gt;. The enthusiasm was short-lived - high fuel requirements, a significant load to the power transmission system, noise and high visibility on battlefield were significant disadvantages that ended the research programs which I know of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still, that's over half a century ago, and the technology has progressed quite a bit since then so maybe some technical problems of that epoch are now past? - The ramjets are small, lightweight and quite simple in construction, so despite the disadvantages the technology doesn't seem like a total dead-end. Was this line of helicopter propulsion investigated further? Could someone provide a progress report - if there is anything to report? Or is this research branch still dead, with no attempts to revive it?&lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="22726" LastEditDate="2018-07-21T02:18:41.997" LastActivityDate="2021-01-28T15:52:01.103" Title="Was there any progress in ramjet-powered helicopters after 1960?" Tags="&lt;helicopter&gt;&lt;experimental-aircraft&gt;&lt;ramjet&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23471" PostTypeId="2" ParentId="23470" CreationDate="2015-12-07T12:22:44.300" Score="9" Body="&lt;p&gt;Short answer: No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or at least, nothing that's been demonstrated that I'm aware of. Whether there have been experimental R&amp;amp;D aircraft or developments, I'm not sure - but I can't find any.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest reason is just because there's no need for them - they offer no real advantages over a conventional internal combustion or jet engine, so as with so much else in aviation we stick with the tried and tested &quot;we know it works&quot; product, unless there's a good reason to change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not necessarily that tip-jet helicopters are a complete dead end in terms of development, just that we don't see any advantages to be gained from them.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-12-07T12:22:44.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23472" PostTypeId="2" ParentId="23429" CreationDate="2015-12-07T12:27:58.410" Score="3" Body="&lt;p&gt;According to the &lt;a href=&quot;https://aviation.stackexchange.com/a/23439/62&quot;&gt;information that @aeroalias found&lt;/a&gt; - which I'm sure is correct - the ICAO definition is used &quot;internally&quot; by the FAA:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FAA has officially adopted the [...] phase of flight taxonomies&#xA;  as an agency-wide data standard for its internal systems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, as far as I can see, that hasn't resulted in a clear definition in the regulations or the FAA's publications. There's nothing in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 1.1&lt;/a&gt; or the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;PCG&lt;/a&gt; and the best I could find - apart from the definition you quoted from the IPH - are sources that imply that en route (or &quot;enroute&quot;) refers to cruise flight only and doesn't include departures and approaches. That would conflict with the ICAO definition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, section 2 of the IPH says what en route airspace is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The en route airspace structure of the National Airspace System (NAS)&#xA;  consists of three strata. The first stratum low altitude airways in&#xA;  the United States [...] are called Victor Airways. [...] The second&#xA;  stratum high altitude airways [...] are called Jet Routes. [...] The&#xA;  third stratum allows random operations above flight level (FL) 450.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's a fairly specific definition that strongly implies that - at least historically, i.e. pre-GPS - en route meant &quot;on the airways&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.3B_Chgs_1-26_rev.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;TERPS&lt;/a&gt; doesn't define en route either, but it does repeatedly suggest that approaches and even feeder routes are &lt;em&gt;not&lt;/em&gt; en route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 3 on initial approaches says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the initial approach, the aircraft has departed the en route phase&#xA;  of flight and is maneuvering to enter an intermediate segment&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Section 2 on feeder routes says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] the angle of intersection between the feeder route course and the en&#xA;  route structure must not exceed 120 degrees&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That seems to me to mean that a) by maneuvering to start an approach you are no longer operating en route, and b) feeder routes are not considered en route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, if you look into some of the FAA's legal interpretations, they seem to say that enroute means cruise flight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2014/duncan%20-%20%282014%29%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Duncan (2014)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] pilots serving as SIC during the en route cruise portion of the flight&#xA;  only [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/Interpretations/data/interps/2014/Barton%20-%20%282014%29%20Legal%20Interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Barton (2014):&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] the pilots identified in both of your questions serve exclusively en&#xA;  route, during the cruise portion of the flight, [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I assume that most pilots would agree that descending/maneuvering to start an approach is no longer cruise flight. But unfortunately there's no formal definition of &quot;cruise&quot; that I could find - apart from possibly the ICAO definition - so that isn't entirely clear either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my take - and I may be completely wrong - is that even in the absence of a formal definition in the regs, there's quite a lot of FAA material that states or implies that en route means cruise flight on an airway or other defined route, and it doesn't include departures and approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for a 'real' answer, you might have to ask your local FSDO for their opinion, or even ask the FAA for an interpretation if you need it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-12-07T12:27:58.410" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23473" PostTypeId="2" ParentId="23460" CreationDate="2015-12-07T13:10:23.813" Score="20" Body="&lt;p&gt;I'm adding this as an answer, because it is too long to be a comment, but it is meant as a supplement to the already accepted answer&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a skydiver of 13 years, and having been a member of two different national teams and three different national skydiving associations (US, NO, DK), I will add that repack cycles are in most countries/states defined for reserve canopies. Both main and reserve canopies have main control inspection intervals as well, where a repack also occurs, ofcourse. The intervals I've come across differs. Student gear have in most cases more frequent cycles, due to the fact that they land in trees and similar, more often than experienced skydivers. Reserve canopies seems to have cycles that somewhat depends on climate, more specifically humidity. Florida for instance has the most frequent reserve repack cycle I've come across. I think it was three months. In Norway however, it is 12 months. I am not a rigger (an educated skydive-gear god), and I haven't checked this specifically, but my impression is that the opening functionality of a canopy &lt;strong&gt;might&lt;/strong&gt; be compromised if it stays compressed for too long, and that humidity speeds up this process. We like the opening sequence to be as predictable as possible, and even though it would probably work anyway, it is better to be on the safe side. It is generally recommended to keep your main canopy unpacked if you are not going to use it for a while, as long as it is not exposed things that might compromise fabric or lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military gear is sometimes round canopies, instead of the standard square sports-canopy. I have no idea how the round ones needs to be packed, but from what I've seen of the military square-jumpers, I wouldn't be surprised if they have the same repack/control cycles as student canopies, and for the same reasons (trees).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I normally repack my main canopy before jumping, if it has been more than 3 months in my container. &lt;/p&gt;&#xA;" OwnerUserId="12573" LastEditorUserId="12573" LastEditDate="2015-12-07T13:21:31.193" LastActivityDate="2015-12-07T13:21:31.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23474" PostTypeId="2" ParentId="23460" CreationDate="2015-12-07T14:17:54.150" Score="7" Body="&lt;p&gt;When I started flying hang-gliders, there were a number of incidents (some fatal) where reserve chutes were thrown but did not deploy properly.  Competence at chute-packing was the main cause, but some came from chutes where the fabric was simply too stuck together.  Clubs started running chute repacking days in local halls or sports centres, sometimes with a zip-wire from the roof which would let you practise throwing your chute under realistic conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For our reserves, we tended to reckon on repacking being a yearly activity, but then many people would go their whole flying career without ever throwing their reserve.  More frequent repacking was not justifiable given the odds of needing it.  If you're skydiving or doing military airdrops, using the chute is non-negotiable, and reducing risks by more regular repacking is very sensible.&lt;/p&gt;&#xA;" OwnerUserId="12155" LastActivityDate="2015-12-07T14:17:54.150" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23476" PostTypeId="2" ParentId="23470" CreationDate="2015-12-07T15:19:42.350" Score="13" Body="&lt;p&gt;Tip jet rotors are still being developed, none of them are ramjet powered as far as I know. The &lt;a href=&quot;http://avimech.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dragonfly DF1&lt;/a&gt; is tip rocket powered, while the &lt;a href=&quot;http://pegasusheli.co.uk/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pegasus&lt;/a&gt; uses air jets powered by a conventional engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ramjet technology has not improved, so the cases for using them on rotor tips has not changed. They are still too heavy, thirsty and noisy.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2018-07-06T07:08:07.203" LastActivityDate="2018-07-06T07:08:07.203" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23477" PostTypeId="2" ParentId="23470" CreationDate="2015-12-07T17:44:37.153" Score="4" Body="&lt;p&gt;I'm reading a &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0971370206&quot; rel=&quot;nofollow&quot;&gt;book&lt;/a&gt; right now that talks briefly about flight testing the Hiller. As I recall, it was tough to get both engines started at the same time, and if one of them cut out,  was a pretty violent affair. It was also an environmental disaster, with horrible fumes and noise. It was an interesting experiment, but it had no real world application at all. There still doesn't appear to be one. &lt;/p&gt;&#xA;" OwnerUserId="9760" LastActivityDate="2015-12-07T17:44:37.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23479" PostTypeId="2" ParentId="22549" CreationDate="2015-12-07T21:12:33.967" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=d76dd4705cd85ab30509c2d9bb6344d6&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1340&quot; rel=&quot;nofollow&quot;&gt;The FAA has a similar requirement&lt;/a&gt; (commercially under part 121)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Except as provided in paragraph (b) of this section, no person may&#xA;  operate an airplane in any overwater operation unless it is equipped&#xA;  with life preservers in accordance with §121.339(a)(1) or with an&#xA;  approved flotation means for each occupant. This means must be within&#xA;  easy reach of each seated occupant and must be readily removable from&#xA;  the airplane.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Upon application by the air carrier or commercial operator, the&#xA;  Administrator may approve the operation of an airplane over water&#xA;  without the life preservers or flotation means required by paragraph&#xA;  (a) of this section, if the air carrier or commercial operator shows&#xA;  that the water over which the airplane is to be operated is not of&#xA;  such size and depth that life preservers or flotation means would be&#xA;  required for the survival of its occupants in the event the flight&#xA;  terminates in that water.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words they are only actually required (per FAA regulations) when operating over water so not every plane (route provided) technically needs them. However many airplane seat bottoms may double as a personal flotation device so many planes are equipped with them by the nature of their construction. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="995" LastEditDate="2016-08-04T02:19:11.987" LastActivityDate="2016-08-04T02:19:11.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23480" PostTypeId="2" ParentId="1641" CreationDate="2015-12-07T21:38:38.683" Score="1" Body="&lt;p&gt;An OpSpecs is basically a contract between the FAA and the Carrier. It grants permission for the carrier to operate and contains the permissions for several parts of the operation. The OpSpecs are created and agreed upon before the carrier receives there certificate to operate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The carrier's (certificate holder's) Manual should ensure that the OpSpecs are upheld or the FAA could pull the carriers certificate. See the following (one is for Part 121 but, it explains a lot): &#xA;&lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/V03%20Tech%20Admin/Chapter%2018/03_018_003.htm&quot; rel=&quot;nofollow&quot;&gt;http://fsims.faa.gov/wdocs/8900.1/V03%20Tech%20Admin/Chapter%2018/03_018_003.htm&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/initiatives/atos/air_carrier/intro_to_part121_cert/&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/about/initiatives/atos/air_carrier/intro_to_part121_cert/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12579" LastActivityDate="2015-12-07T21:38:38.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23481" PostTypeId="1" CreationDate="2015-12-08T02:14:13.383" Score="-3" ViewCount="359" Body="&lt;p&gt;I want to know the effect of the wingtip vortex to design a winglet (or a wing horizontal extension) to counteract* this effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How could I calculate the momentum produced by the tip vortex, in order to calculate  geometrical characteristics of the winglet to compensate this momentum?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I knew the velocity of the vortex, how could calculate the produced momentum?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you.&lt;/p&gt;&#xA;" OwnerUserId="12581" LastEditorUserId="12581" LastEditDate="2015-12-08T04:27:10.543" LastActivityDate="2015-12-08T05:48:48.343" Title="Design winglets to counteract tip vortex" Tags="&lt;winglets&gt;&lt;wing-tip-vortex&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ClosedDate="2015-12-08T07:34:02.103" ContentLicense="CC BY-SA 3.0" />
  <row Id="23482" PostTypeId="2" ParentId="23431" CreationDate="2015-12-08T02:31:03.863" Score="-2" Body="&lt;p&gt;It was probably BS and the attendant was just being overly cautious. They probably say that on &lt;em&gt;any&lt;/em&gt; flight with a half-full cabin. There is no way to know for sure however without more information about the loading of the aircraft whether it was legitimate or not. If the flight attendant made a general announcement and it was the pursuer who did so, it is much more likely that it was real, because that is who the captain would have given the instruction to. If it was some random attendant just telling you personally not to move, it was probably BS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, moving around when a plane is taking off is a very bad idea at multiple levels because you could hurt yourself or someone else. You should always remain seated and buckled in when an aircraft is taking off or landing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-12-08T02:31:03.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23483" PostTypeId="1" AcceptedAnswerId="23484" CreationDate="2015-12-08T04:50:10.690" Score="3" ViewCount="735" Body="&lt;p&gt;Last time I boarded a flight (Boeing 717 with Delta, with assigned seats), the passengers were split into 4 groups and allowed to board the plane in an order that filled seats from front to back. I can understand why first/business class could go first, since they pay more. But the rest of the passengers pay the same rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it be more efficient to let the passengers that sit in the back board first? Or maybe even to just let everyone board in random order.&lt;/p&gt;&#xA;" OwnerUserId="12551" LastActivityDate="2015-12-08T05:36:12.493" Title="Why are airplane passengers boarded from front to back?" Tags="&lt;efficiency&gt;&lt;boarding&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-08T07:50:54.847" ContentLicense="CC BY-SA 3.0" />
  <row Id="23484" PostTypeId="2" ParentId="23483" CreationDate="2015-12-08T05:23:13.160" Score="3" Body="&lt;p&gt;A number of airlines (including &lt;a href=&quot;http://www.delta.com/content/www/en_US/traveling-with-us/onboard-experience/boarding-priority.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Delta&lt;/a&gt;) use a &lt;a href=&quot;http://www.seatguru.com/articles/boarding_procedures.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;'zone boarding' procedure&lt;/a&gt;. In short, the first/business class board first, followed by 'blocks' of passengers, usually from rear to front (In your aircraft, this was apparently done the opposite way).&lt;/p&gt;&#xA;&lt;p&gt;However, it is important to point out that the back-to-front is not very efficient, atleast if you take into account the time taken to seat everyone. &lt;a href=&quot;http://arxiv.org/abs/1108.5211&quot; rel=&quot;nofollow noreferrer&quot;&gt;Experimental evidence&lt;/a&gt; indicates that the back to front method is one of the least efficient of all the boarding methods. The table below shows the time taken for 72 people to board a (mock) airplane using various methods.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Nidom.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nidom.png&quot; alt=&quot;Comparison of methods&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Table from &lt;em&gt;Experimental test of airplane boarding methods&lt;/em&gt; by Jason H. Steffen and Jon Hotchkiss&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.theatlantic.com/business/archive/2014/11/theres-a-better-way-to-board-planes/383181/&quot; rel=&quot;nofollow noreferrer&quot;&gt;basic problem in following back-to-front method&lt;/a&gt;, according to the author is that it is a serial process:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The passengers would rush into the cabin, proceed toward the back—and come to a screeching halt as the first one or two passengers stowed their luggage. The first 30 passengers (the back five rows) would take up nearly the entire length of the cabin. The rest of the line has simply moved from the airport gate into the jetway or cabin—and it moves no faster.&lt;/p&gt;&#xA;&lt;p&gt;... In this case, only one passenger at a time is seated. The aisle in the airplane isn’t used effectively.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There has also been studies on &lt;a href=&quot;http://arxiv.org/pdf/0802.0733.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;optimal boarding procedures&lt;/a&gt;, which indicate that optimal procedure is different from what any airline follows.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;There was a &lt;a href=&quot;http://mythbustersresults.com/airplane-boarding&quot; rel=&quot;nofollow noreferrer&quot;&gt;mythbusters episode&lt;/a&gt; that simulated boarding an airplane using various methods in vogue. Making allowances for the lack of scientific rigor, the results of boarding 173 passengers were pretty much the same- back-to-front is the slowest method.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h5dBE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h5dBE.png&quot; alt=&quot;Mythbusters boarding&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from mythbustersresults.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-08T05:36:12.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23485" PostTypeId="2" ParentId="23481" CreationDate="2015-12-08T05:48:48.343" Score="5" Body="&lt;p&gt;Please stop following the cult of the wingtip vortex and start to gain a better understanding of the flow around a wing. Stop reading if you encounter any of those myths:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pressure differences at the tip produce a flow around the tip, starting the vortex. &lt;strong&gt;Oversimplification!&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;li&gt;The tip vortex causes drag. &lt;strong&gt;Wrong!&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the web and much of unscientific literature is full of such myths. Authors with little understanding of the subject copy what they find without considering better sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, however, you find statements like these:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The wing sheds a sheet of vorticity along its span.&lt;/li&gt;&#xA;&lt;li&gt;The vortex strength behind a wing is proportional to the lift produced and inversely proportional to flight speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;you have good reason to believe that the author knows his stuff. Read on!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to calculate the local flow speed and direction in the vicinity of the wing, all you need is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Biot%E2%80%93Savart_law#Aerodynamics_applications&quot; rel=&quot;nofollow noreferrer&quot;&gt;Biot-Savart law&lt;/a&gt; and apply it in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerodynamic_potential-flow_code&quot; rel=&quot;nofollow noreferrer&quot;&gt;panel code&lt;/a&gt;. This calculates the influences of the vorticity on all parts of the wing at a specific location and adds them up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a list of other answers on Stack Exchange which you might find helpful in gaining a better understanding of aerodynamics and freeing yourself from the wingtip vortex myth:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=2%7C0.0535#8882&quot;&gt;How does an aircraft form wake turbulence?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension/8579#8579&quot;&gt;Is a winglet better than an equal span extension?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/23125/how-can-i-get-started-on-a-winglet-design-for-a-small-remote-controlled-aircraft/23128?s=1%7C0.4734#23128&quot;&gt;How can I get started on a winglet design?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-12-08T05:48:48.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23486" PostTypeId="1" AcceptedAnswerId="23487" CreationDate="2015-12-08T08:33:36.100" Score="4" ViewCount="591" Body="&lt;p&gt;I stumbled on a new chinese one &lt;a href=&quot;http://www.china.org.cn/photos/2015-12/08/content_37261878_8.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;: The &quot;&lt;strong&gt;Snow Eagle 601&lt;/strong&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NtdeC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NtdeC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone expand a little?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first sight, I can't make any relevant difference from a regular one (It just looks like a stock DC3 fitted with new turboprop engines + snow skis for the purpose).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything to do with the plane's performance required by the toughness of elements in the poles?&lt;/p&gt;&#xA;" OwnerUserId="247" LastEditorUserId="7611" LastEditDate="2015-12-08T08:54:00.337" LastActivityDate="2015-12-08T09:14:14.377" Title="What is a Polar airplane?" Tags="&lt;plane-spotting&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23487" PostTypeId="2" ParentId="23486" CreationDate="2015-12-08T09:14:14.377" Score="9" Body="&lt;p&gt;The aircraft is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Basler_BT-67&quot;&gt;Basler BT-67&lt;/a&gt;, which is a retractable wheeled ski equipped undercarriage STOL aircraft. It is a remanufactured DC-3 with Pratt &amp;amp; Whitney Canada PT6A-67R turboprop engine. The &lt;a href=&quot;http://www.baslerturbo.com/power-and-performance.html&quot;&gt;modifications include&lt;/a&gt; lengthened fuselage, increased MTOW, new avionics, redesigned wingtips etc. The skis are added in Canada.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reports indicate that the &lt;a href=&quot;http://www.china.org.cn/photos/2015-12/08/content_37261878_3.htm&quot;&gt;aircraft includes&lt;/a&gt; an ice radar system, airborne gravimeter, airborne magnetometer and onboard laser radar system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is called a 'polar' airplane because it is owned by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Chinese_Arctic_and_Antarctic_Administration&quot;&gt;Chinese Arctic and Antarctic_Administration&lt;/a&gt;. The aircraft is used by quite a few other missions in Antarctica, like &lt;a href=&quot;http://www.antarctica.gov.au/living-and-working/travel-and-logistics/aviation/intracontinental-operations/basler-bt-67-aircraft&quot;&gt;Australia&lt;/a&gt; and the &lt;a href=&quot;https://www.nsf.gov/geo/plr/support/twinottr.jsp&quot;&gt;US&lt;/a&gt;, all operated by the Kenn Borek Air.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-08T09:14:14.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23488" PostTypeId="1" AcceptedAnswerId="23500" CreationDate="2015-12-08T09:48:25.177" Score="3" ViewCount="1057" Body="&lt;p&gt;As example &quot;&lt;a href=&quot;http://www.scpoa.com/airport/&quot; rel=&quot;nofollow&quot;&gt;Spruce Creek&lt;/a&gt;&quot;. Many residents own private aircraft and can fly anytime they want. Do they have an separate air traffic controller? How is this high amount of air traffic managed?&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="1696" LastEditDate="2015-12-08T15:37:17.163" LastActivityDate="2018-02-12T02:40:42.120" Title="How is the air traffic managed at a field with many privately owned aircraft?" Tags="&lt;air-traffic-control&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23490" PostTypeId="2" ParentId="23488" CreationDate="2015-12-08T10:59:27.443" Score="2" Body="&lt;p&gt;ATC is responsible for all aircraft, not only commercial IFR, but also general aviation IFR and VFR. Some airports may have restrictions (EDDM - Munich does not accept VFR below 2to MTOM), but in most other cases VFR general aviation is sequenced between IFR commercial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Enroute VFR traffic may not necessarily be on the same frequencies, some countries offer own Flight Information Services for VFR traffic, where separation is not required, some airspaces that are shared require separation and will have both aircraft on the same frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of &lt;a href=&quot;http://www.scpoa.com/airport/&quot; rel=&quot;nofollow&quot;&gt;Spruce Creeks&lt;/a&gt;, there is a listed CTAF frequency, on which aircraft will be in the vicinity of the airfield. Leaving the airfield vicinity, they will join the regular frequencies for the services they require enroute.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2015-12-08T10:59:27.443" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23491" PostTypeId="2" ParentId="3466" CreationDate="2015-12-08T11:01:42.623" Score="4" Body="&lt;p&gt;The majority of maintenance manuals are customised for a specific fleet, i.e. specific to a particular airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That way Boeing only provides information that is applicable to those aircraft and even with a given manual you need to be able to filter on applicability to ensure that specific maintenance information is applicable to a specific aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having worked with airlines using Boeing maintenance data, the position pre-B787 was that the maintenance manuals were owned by the airlines but that Boeing were responsible for the original content. Boeing seem to be trying to change that for the B787, possibly in an attempt to get all B787 customers to use their &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_1_07/article_04_1.html&quot; rel=&quot;nofollow&quot;&gt;Maintenance Performance Toolbox&lt;/a&gt; authoring/consultation tool instead of being able to use third party solutions or even Airbus's &lt;a href=&quot;http://www.airbus.com/support/maintenance-engineering/e-solutions/&quot; rel=&quot;nofollow&quot;&gt;Maintenance documentation solution&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So back to the original question, the answer is Yes , if an airline gives it to you, or No if you go knocking on Boeing's door.&lt;/p&gt;&#xA;" OwnerUserId="12585" LastEditorUserId="1467" LastEditDate="2015-12-08T11:17:25.740" LastActivityDate="2015-12-08T11:17:25.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23492" PostTypeId="1" CreationDate="2015-12-08T11:20:09.597" Score="5" ViewCount="1219" Body="&lt;p&gt;Does the autothrottle realign the throttle lever positions? If the throttle is staggered, does it mean that there is an issue on the engines?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-12-08T13:19:32.143" Title="Is it possible to fly with throttles staggered?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23493" PostTypeId="2" ParentId="23492" CreationDate="2015-12-08T11:30:07.797" Score="9" Body="&lt;p&gt;Yes it is possible - as mentioned in a comment, most multi-engine aircraft can (fairly) happily fly with one engine at idle or disabled entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some autopilots will use some asymmetric thrust for yaw trim, and others will use asymmetric throttle settings to compensate for the engines producing different amounts of thrust. Those sound similar, but aren't &lt;em&gt;quite&lt;/em&gt; the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example here's a description of that happening on the 777. Neither are ubiquitous and both depend on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flight.org/the-boeing-777-thrust-asymmetry-compensation-tac&quot;&gt;http://www.flight.org/the-boeing-777-thrust-asymmetry-compensation-tac&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that two engines can never be identical, there will &lt;em&gt;always&lt;/em&gt; be some level of asymmetric thrust. Traditionally this was countered with rudder trim, but newer aircraft sometimes adjust the throttle instead, as per the above link&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2015-12-08T13:19:32.143" LastActivityDate="2015-12-08T13:19:32.143" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23494" PostTypeId="1" CreationDate="2015-12-08T13:47:02.507" Score="5" ViewCount="1120" Body="&lt;p&gt;A cracked windshield in flight will decrease the performance. To what extent can it disrupt the flight? Can flakes of glass be ingested on tail-mounted engines? Is it possible to blow out the windshield because of the high speed?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="62" LastEditDate="2015-12-08T14:49:47.893" LastActivityDate="2015-12-08T16:51:52.690" Title="How is performance downgraded if the windshield is damaged in flight?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23495" PostTypeId="1" CreationDate="2015-12-08T13:57:41.903" Score="61" ViewCount="26560" Body="&lt;p&gt;Being a commercial airline pilot regularly appears around the top of &quot;most stressful jobs&quot; lists.  I do not doubt that this is a stressful job, but as an outsider with no aviation experience whatsoever I do not understand why.  I am curious to hear a first-hand explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have always imagined flying long-haul to become very tedious and repetitive after a while.  The only significant source of stress I can see is time away from family/relationships (which admittedly I couldn't cope with, but it doesn't seem sufficient a reason to propel this to the front of most stressful professions).&lt;/p&gt;&#xA;" OwnerUserId="12587" LastActivityDate="2018-01-24T06:42:57.943" Title="Why is being a commercial pilot stressful?" Tags="&lt;pilots&gt;&lt;airline-pilot&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="23496" PostTypeId="2" ParentId="23495" CreationDate="2015-12-08T14:02:14.173" Score="7" Body="&lt;p&gt;I am not a pilot, but just on top of my head:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Stressful situations which require high amounts of attention to the smallest details&lt;/li&gt;&#xA;&lt;li&gt;Responsibility for human lives&lt;/li&gt;&#xA;&lt;li&gt;Tight schedules with small amount of time to rest&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The flight duration doesn't matter, extreme situations can occur at all times.&lt;/p&gt;&#xA;" OwnerUserId="11787" LastActivityDate="2015-12-08T14:02:14.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23497" PostTypeId="2" ParentId="23495" CreationDate="2015-12-08T14:22:18.543" Score="6" Body="&lt;p&gt;Why is being a commercial pilot stressful? On a normal flight, the pilots take off, communicate with ATC, change some parameters in the navigation computer from time to time, and land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While on the ground, the pilots have to visually inspect the aircraft and prepare the whole flight. This includes flight-planning, analysis of weather-forecasts, fuel calculations and many more things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specially on short-haul-flights, every minute counts. If a plane arrives ten minutes to late, passengers could miss their next flight. Every following flight of this late airplane gets delayed too. This is a stress-factor for pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From Phantomazi's answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Stressful situations which require high amounts of attention to the smallest details&lt;/li&gt;&#xA;  &lt;li&gt;Responsibility for human lives&lt;/li&gt;&#xA;  &lt;li&gt;Tight schedules with small amount of time to rest&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see, the flying might not be the part which is most stressing for the pilots. What's stressing is the whole thing around.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="12602" LastEditDate="2015-12-09T17:08:31.433" LastActivityDate="2015-12-09T17:08:31.433" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23499" PostTypeId="2" ParentId="23495" CreationDate="2015-12-08T14:47:10.450" Score="100" Body="&lt;p&gt;The stress comes from everything about the job that isn't actually flying the plane.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Dealing with crew scheduling is the #1 cause of stress.  If your phone rings with that special ringtone you assigned to them, you know nothing good is going to come of it.  These calls often end with reassignments, changed overnights, different crew members and sometimes extensions into days off.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dealing with a stubborn dispatcher who, despite the mess of storms on your route, refuses to give you an extra 500# contingency fuel.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dealing with pressure for on-time departures.  This usually comes from a gate agent because they generally are the ones who get the short end of the stick if we push late.  This can be exacerbated by agents who know about certain &quot;tricks&quot; to fool the system into thinking you pushed, which are often specifically disallowed by flight operations.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Winter operations.  Figuring out where de-ice happens, what special flow control might be in effect and managing holdover times can be a headache, particularly at unfamiliar fields. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Spring and summertime.  Never a moments rest during cruise but instead a constant look on the horizon and the radar and requesting deviations from every controller you talk to.  These seasons often have days with widespread thunderstorm activity.  These storms for the most part must be avoided and sometimes require constant coordination with controllers to deviate off-route to go around them.  This creates fatigue more than stress, but the two have a way of feeding back on each other.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Holding.  Do we really have the gas to be doing this?  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Diverting.  Coordinating with dispatch, maintenance (if needed), operations at the field, ATC and passengers.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Timing out.  Hey folks, sorry we diverted but now we timed out, we're staying the night here.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Crew scheduling, again, to get hotel rooms and find out just how bad this day screwed our schedules for the next few days.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;That once yearly visit to the AME where you are reminded just how bad your airport junk food diet is and where exactly &quot;hypertension&quot; starts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Commuting.  It is fairly common that pilots do not live in their base and live far enough away that the commuting means jumpseating or non-rev flying to get to work and back home.  Depending on where you live you can often encounter oversold flights, competition for the jump seats and little backup options for same-day travel (e.g. not flying in the day before your trip).  Not making it work can have consequences depending on how hard you tried to make it work and how good your union contract and chief pilots are.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of note, I never found actually flying the plane stressful including operations in low visibility and high winds.  Those are the things that kept the job interesting and I quite enjoyed them.  Having people in the back was also never stress inducing.  As long as I flew safely and kept myself alive, the passengers would end up that way also.  I was mindful of the passengers in selecting alternate cruise altitudes for ride conditions and requesting shortcuts from ATC to make up time but those are not stressful things to do.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-12-11T19:26:44.333" LastActivityDate="2015-12-11T19:26:44.333" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="23500" PostTypeId="2" ParentId="23488" CreationDate="2015-12-08T14:52:38.670" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How is this high amount of air traffic managed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Air traffic is managed at many levels by many people and is heavily dependent on the airports specifics when it comes to GA. First off not every airplane in the sky is talking to or under control of ATC, for that mater in some airspaces you don't even need a radio on board. The following is pursuant to US FAA regulations, other countries may handle air traffic differently.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first level of traffic management is the pilot, its the job of every pilot to &quot;&lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/August/Pilot/counsel&quot; rel=&quot;noreferrer&quot;&gt;see and avoid&lt;/a&gt;&quot; other traffic, this goes for both commercial and general aviation traffic. Even if issued a command by ATC you can deviate to avoid an emergency (i.e. hitting another plane). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next level of traffic management is the various FAA regulations on both ground and air flight operations. These regulations (like traffic rules) are laws and must be followed. They are designed to mitigate traffic in certain areas and will also force you in some areas to at least be on the radio with ATC (e.g. class B airspace). You can read up on the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2e383ba8447bf62677d9c1bf661de901&amp;amp;mc=true&amp;amp;node=pt14.2.91&amp;amp;rgn=div5#sp14.2.91.b&quot; rel=&quot;noreferrer&quot;&gt;full regs here&lt;/a&gt; and you will find most of what you are looking for under &quot;flight rules&quot;. Much of the country (below 18,000Ft and above 1200ft generally) is actually class E airspace which does not require ATC communications. This is where most GA traffic lives although small turbo props and the boldest of piston singles can now make it into the levels, most GA planes cant. There are also pre set cruising altitude intervals for VFR and IFR traffic to help keep separation.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above that you will have ATC who is controlling all &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;noreferrer&quot;&gt;IFR traffic&lt;/a&gt;, traffic in &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspace_class_(United_States)&quot; rel=&quot;noreferrer&quot;&gt;Class A, B, C, and D airspace&lt;/a&gt; and will provide limited radar services to VFR traffic when load permits. When flying under &lt;a href=&quot;https://en.wikipedia.org/wiki/Visual_flight_rules&quot; rel=&quot;noreferrer&quot;&gt;VFR&lt;/a&gt; (depending on where you are) you may not need to ever talk to ATC. It is possible to depart an un-towered airport in class G or E airspace, fly around and return with out ever having contacted an ATC facility. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground control depends on the airport. At an &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/awp/media/education/safety%20advisor%20non-towered%20airports.pdf&quot; rel=&quot;noreferrer&quot;&gt;uncontrolled field&lt;/a&gt; (lots of smaller general aviation airports) the pilots decide. Taxing around is much like driving a car and there are pre determined radio calls to enter the traffic pattern and use the active runway. At a &lt;a href=&quot;http://flighttraining.aopa.org/students/solo/topics/SA07_Towered_Airport_Ops.pdf&quot; rel=&quot;noreferrer&quot;&gt;towered airport&lt;/a&gt; ground control will monitor and control the flow of traffic on the ramp and the tower will control the traffic from the runway thresholds until the plane departs its airspace.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only exceptions to the rules here in the US are 5 airports (LaGuardia, Newark,  O'Hare, Ronald Reagan National, and John F. Kennedy) which are &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b144a66d522a5551d09e6e284d15af2c&amp;amp;mc=true&amp;amp;node=se14.2.93_1123&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;subject to the FAA's high density airport rules&lt;/a&gt; (specific to the airports) generally speaking the operations are the same in terms of how ATC will handle a given aircraft but departures and arrivals are limited and must be reserved ahead of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another note on IFR operations, ATC will treat all planes the same and will only give priority to a plane in an emergency. Your little Cessna 172 on an IFR flight will receive the same services as a 747 30,000ft above you.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do they have an separate air traffic controller?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No. See above but for what its worth the big planes contact the same ATC facilities as the little guys.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Spruce Creek&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth Spruce Creek sits under a Class C shelf as you can see on the sectional here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LpNqh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LpNqh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Departing from RW 5 and staying below 1200 puts you right between the Daytona Class C and New Smyrna Beach Class D so you may find your self contacting ATC on departure depending on your route you are somewhat boxed in there. Even departing from 23 you may find your self contacting Daytona approach to punch into the Class C there. Technically you can get out of there with out contacting ATC but you may find your self needing to depending on the situation.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-08T21:34:46.637" LastActivityDate="2015-12-08T21:34:46.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23502" PostTypeId="2" ParentId="23494" CreationDate="2015-12-08T16:03:39.913" Score="6" Body="&lt;p&gt;The biggest restriction will be the reduced flight speed and cabin pressure which need to be observed with a damaged windshield. No pressurization will restrict the flight altitude to 10,000 ft or less. The crack will not increase drag, but force the pilot to continue flight at a less efficient speed and altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why high altitude is good for engine efficiency can be &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983#4983&quot;&gt;found here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How to find the most efficient flight speed can be &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623?s=2%7C0.4659#3623&quot;&gt;read here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If pieces break off, the aircraft should not continue the flight, but land immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the other questions: Yes, sure, tail-mounted engines are known for ingesting stuff which has broken off from the fuselage. Ice from a leaking lavatory &lt;a href=&quot;https://aviation.stackexchange.com/questions/2361/where-does-my-pee-go-when-i-flush-at-35-000-ft/14065#14065&quot;&gt;has caused engine damage and the imbalance made the engine shake so hard that it fell off&lt;/a&gt;. The whole windshield or substantial fractions of it could have this effect, but I doubt that flakes will damage the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic pressure at the windshields tends to press them into the fuselage. Suction only starts above of the windshield with the curvature of the fuselage contour. However, with cabin pressurization added, the windshield is indeed forced out if it fails. One accident which was caused by using the wrong screws to secure the windshield is &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_5390&quot; rel=&quot;nofollow noreferrer&quot;&gt;BA Flight 5390&lt;/a&gt;. The captain was sucked out of the opening left by the window and only his ankles, which got stuck in the flight controls, prevented him from falling out entirely.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-08T16:51:52.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23503" PostTypeId="2" ParentId="23494" CreationDate="2015-12-08T16:23:37.690" Score="3" Body="&lt;p&gt;This depends on how the windshield is damaged.  Aircraft windscreens are often multi-layer and can withstand cracks in the outermost layer.  If this is the only damage then the flight can operate as normal and write up the airplane so that maintenance looks at it before returning the airplane to service.  If the inner layers are cracked then the things mentioned in Peter's answer come into effect.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically in the EMB-145 I operated:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;if only the outer layer is cracked, no action is necessary&lt;/li&gt;&#xA;&lt;li&gt;if the inner layer is cracked&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;descend to 10,000 or MEA and maintain pressurization at $\Delta$P at 1 PSI&lt;/li&gt;&#xA;&lt;li&gt;If both windshields are impaired&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;depressurize&lt;/li&gt;&#xA;&lt;li&gt;max airspeed 140 KIAS.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the case the inner layer is cracked, this will likely turn into a diversion coordinated with maintenance to either swap an airplane or wait for repairs to be made.  With both windshields cracked and completely obscured &lt;a href=&quot;https://aviation.stackexchange.com/a/13075/258&quot;&gt;landing becomes a lot more interesting&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-08T16:23:37.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23504" PostTypeId="1" AcceptedAnswerId="23505" CreationDate="2015-12-08T19:07:15.680" Score="38" ViewCount="5436" Body="&lt;p&gt;I'm reading through TheStar's &quot;&lt;a href=&quot;http://www.thestar.com.my/news/nation/2015/12/08/wanted-plane-klia/&quot;&gt;Malaysia Airports seeks owner of three Boeing 747s abandoned at KLIA&lt;/a&gt;&quot; article and I can't stop wondering, why I don't understand it or how should I understand it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How it is possible in 21th century, that knowing large passenger aircraft's (a) type, (b) current location and &lt;strong&gt;(c) registration&lt;/strong&gt; it is still impossible to find actual aircraft's owner in a matter of minutes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't we have aircraft's databases, to obtain this information? Or to use it to track any passenger aircraft latest flights? Is it possible, that Kuala Lumpur International Airport does not have any records or tracks of what (owned by whom) and when landed on their grounds?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that this isn't possible, but for a newbie like me this article sound like a joke rather than a current reality in aviation industry today.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="62" LastEditDate="2015-12-08T21:53:49.360" LastActivityDate="2015-12-10T03:26:58.703" Title="How can a large passenger aircraft's owner remain unknown?" Tags="&lt;airline-operations&gt;&lt;datasets&gt;&lt;aircraft-ownership&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23505" PostTypeId="2" ParentId="23504" CreationDate="2015-12-08T19:17:36.530" Score="33" Body="&lt;p&gt;Every country handles aircraft registration differently (but generally similar). Im sure Boeing could tell you who they originally delivered the airframe to but if it was sold from there it could legally go anywhere and would only be subject to local registration legislation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here in the &lt;a href=&quot;http://registry.faa.gov/aircraftinquiry/NNum_Inquiry.aspx&quot;&gt;US you can look up aircraft owners by N number&lt;/a&gt; but not all countries may keep a record like that and as far as I know there is no global aircraft registry. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;it is still impossible to find actual aircraft's owner in a matter of minutes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Knowing who the owner is and &lt;em&gt;finding&lt;/em&gt; the owner are two very different things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.cnn.com/2015/12/08/aviation/malaysia-aviation-airport-abandoned-aircraft/index.html&quot;&gt;According to this article&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Several aviation databases list the Boeings -- identified by their&#xA;  call signs TF-ARN, TF-ARH, TF-ARM -- as belonging to leasing firm Air&#xA;  Atlanta Icelandic, but that company says it sold them in 2008.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Since then, the aircraft appear to have changed hands several times.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Malaysia Airports says it's entitled to sell the Boeings under the&#xA;  country's civil aviation regulations if no owner comes forward.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it seems they do know who owned them at some point (most likely the last people to put readable registration numbers on them). &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="100" LastEditDate="2015-12-09T08:57:25.720" LastActivityDate="2015-12-09T08:57:25.720" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23506" PostTypeId="2" ParentId="23504" CreationDate="2015-12-08T19:20:18.247" Score="11" Body="&lt;p&gt;There's certainly some missing details in that story. Two minutes with Google shows that (a) the prefix &quot;TF&quot; refers to Iceland, and (b) those three aircraft were most recently registered to &lt;a href=&quot;http://www.atlanta.is/&quot;&gt;Air Atlanta Icelandic&lt;/a&gt;, some sort of charter/cargo operator. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's missing from that news story is that surely the Malaysian authorities have already done the above, and have been unable to contact the registered owner for whatever reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interesting is that the &lt;a href=&quot;http://www.ch-aviation.com/portal/aircraft/quick?phrase=Air+Atlanta+Icelandic&quot;&gt;Air Atlanta Icelandic fleet&lt;/a&gt; as listed by ch-aviation does not include those three registration numbers. So maybe they've been sold to someone else.&lt;/p&gt;&#xA;" OwnerUserId="675" LastActivityDate="2015-12-08T19:20:18.247" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23507" PostTypeId="1" AcceptedAnswerId="23509" CreationDate="2015-12-08T19:29:53.890" Score="7" ViewCount="1847" Body="&lt;p&gt;I wonder how is designed the command chain from the throttle lever or the auto-throttle to the fuel injection in recent jetliners. I have 4 questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is set by the throttle?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the pilot actuates the throttle, what are they setting exactly? (I can imagine the lever position corresponds to a fuel rate, to a RPM, to a thrust value, etc).&lt;/li&gt;&#xA;&lt;li&gt;Is this value a linear function of the throttle position (e.g. 73% of the full lever rotation is 73% of the maximum N1).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is the throttle output standardized or customized for an engine model?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What type of output has the throttle lever: mechanical, electric, digital data?&lt;/li&gt;&#xA;&lt;li&gt;Which subsystems in the engine receive the throttle output(s)?&lt;/li&gt;&#xA;&lt;li&gt;Is this output customized/calibrated for an engine model, or standardized.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How are the throttle outputs processed in the engine?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the electronic engine control apply further adjustment to the throttle input? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How does the auto-throttle (auto-thrust) interact with the manual throttle?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the auto-throttle send its command directly to the engine or to the mechanical throttle?&lt;/li&gt;&#xA;&lt;li&gt;Is the manual throttle position adjusted, according to the A/T output?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="19" LastEditDate="2017-01-09T09:48:18.380" LastActivityDate="2017-01-10T00:10:31.320" Title="What is the relation between throttle position and engine thrust for a turbofan?" Tags="&lt;jet-engine&gt;&lt;throttle&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23509" PostTypeId="2" ParentId="23507" CreationDate="2015-12-08T20:48:24.550" Score="5" Body="&lt;p&gt;Check out this &lt;a href=&quot;http://www.grc.nasa.gov/WWW/cdtb/aboutus/Fundamentals_of_Engine_Control.pdf&quot; rel=&quot;nofollow&quot;&gt;Nasa powerpoint&lt;/a&gt; it provides a nice overview of some of the basics and how some of the systems are set up. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Does the auto-throttle send its command directly to the EEC or to the&#xA;  mechanical throttle?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This may vary from design to design but the &lt;a href=&quot;http://pig.sagepub.com/content/210/2/181.abstract&quot; rel=&quot;nofollow&quot;&gt;Boeing 777 uses the ARNIC standard bus to send control signals to servos&lt;/a&gt; that physically move the throttle levers. You can read up on the &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow&quot;&gt;ARNIC 429 data bus here&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are the throttle levers customized/calibrated for an engine model, or&#xA;  are their output standardized (assuming the output is an electric&#xA;  signal). Does the electronic engine control apply further adjustment&#xA;  to the throttle input?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems that &lt;a href=&quot;https://www.rockwellcollins.com/Data/Products/Controls/Pilot_Controls/Throttle_Controls.aspx&quot; rel=&quot;nofollow&quot;&gt;Rockwell Collins makes a unit that sends signals to the FADEC system&lt;/a&gt; instead of mechanically actuating anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in mind Im sure there are older designs out there that are closer to or a complete direct linkage from lever to engine.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this correction transmitted back to the throttle lever?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I dont think so, it seems that when say full throttle is applied the throttle control will remain at full and the FADEC unit will take care of spooling it up as need be. Likewise if an engine suddenly cuts out or fuel flow becomes restricted as far as I know the throttles will remain in place. Auto throttle units will however physically actuate the throttles as need be. As per the comments here it seems this is only the case in Boeing aircraft. Airbus throttles must be set to maximum setting auto-throttle is allowed to use. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-08T21:08:18.533" LastActivityDate="2015-12-08T21:08:18.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23510" PostTypeId="2" ParentId="23488" CreationDate="2015-12-08T21:26:11.443" Score="3" Body="&lt;p&gt;At untowered airfields, like Spruce Creek there is no &quot;ATC,&quot; the pilots self organize.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, the way this works is that as you approach you announce your arrival on the common frequency used by the airfield, 122.975 in the case of Spruce Creek. This frequency is listed both on aeronautical charts and in the FAA airport directory. So, for example, you might say something like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Spruce Creek, November niner seven six five four, Cessna one seven two, three miles out on one eight zero, request runway, Spruce Creek&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other pilots at the airfield will hear you and react appropriately. As you get closer you repeat your announcement and intentions. For example, the pilot might say:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Spruce Creek, November niner seven entering downwind for two three, traffic in sight, Spruce Creek&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the traffic is so heavy that you cannot enter the landing pattern, then you bear off and do a circle or racetrack pattern away from the airfield and try to approach again later. Often registrations will be abbreviated in various ways. For example, instead of saying &quot;November niner seven six five four&quot; every time, if you are the only Cessna, you can just say &quot;Cessna&quot;, and the other pilot, say it is an Archer or Cherokee, will just say &quot;Archer&quot; or &quot;Cherokee&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-12-08T21:26:11.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23511" PostTypeId="2" ParentId="21961" CreationDate="2015-12-08T23:00:01.783" Score="5" Body="&lt;p&gt;Helicopter engines have different operating parameters than aircraft engines. They operate in a narrower power band and the difference in horsepower would be due to  camshaft lift and duration optimized for that power band. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2015-12-08T23:00:01.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23512" PostTypeId="1" CreationDate="2015-12-08T23:25:09.550" Score="3" ViewCount="346" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sY8fg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sY8fg.jpg&quot; alt=&quot;Image from www.iconaircraft.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been looking at the &lt;a href=&quot;http://www.inconaircraft.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;website&lt;/a&gt; for the Icon A5 amphibian LSA and noticed the wing section clearly has two different cross sections, presumably to facilitate the stall and spin resistance of the aircraft.  One of the videos on the site shows the wing as it stalls and the tell-tales attached to the wing clearly show the flow separation for the inboard section of the wing while the outer section still indicates attached flow.  I would guess that this wing must have either some performance trade offs or else it's a significant cost, otherwise why wouldn't most GA aircraft have this feature?  Perhaps fabrication in sheet metal would be difficult as I believe this aircraft is mostly composite construction.&lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2020-07-22T11:07:14.057" Title="What are the performance trade-offs in the Icon A5 spin resistant airframe?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23513" PostTypeId="1" AcceptedAnswerId="23515" CreationDate="2015-12-08T23:29:51.223" Score="5" ViewCount="568" Body="&lt;p&gt;I know that it is kerosene based, but what exactly goes into it? Proportions of the various components would be helpful.&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2015-12-09T05:22:05.213" Title="What is Jet-A made of?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2015-12-09T09:03:01.323" ContentLicense="CC BY-SA 3.0" />
  <row Id="23515" PostTypeId="2" ParentId="23513" CreationDate="2015-12-09T01:01:13.070" Score="8" Body="&lt;p&gt;Sadly, that information's pretty much impossible to give a general answer for, as it changes from batch to batch:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Refineries blend crude &quot;to taste&quot; as well as pricetag, so to speak, and the crude blend used as the refinery feedstock may change from batch to batch.&lt;/li&gt;&#xA;&lt;li&gt;Process conditions in catalytic crackers and reformers can change depending on the point in the batch you're at, the incoming feedstock, and even the history of prior batches (say the last thing that ran through the cat cracker degraded the catalyst slightly...)&lt;/li&gt;&#xA;&lt;li&gt;Jet fuels as-delivered may be a blend of multiple refinery batches and even the output of multiple refiners&lt;/li&gt;&#xA;&lt;li&gt;Pipeline batching can also lead to subtle changes in fuel composition as it is transported -- pipeline operators try to &quot;cut off&quot; as much of the transmix as they can, but 100% isn't easy without wasting tons of fuel as transmix.  (Some pipeline operators will stick a &quot;dumb pig&quot; between high spec products, such as jet fuel, and their neighbors in the pipeline, but this is by no means universal.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That said, you can make some determinations based off of &lt;a href=&quot;http://www.cpchem.com/msds/100000014588_SDS_US_EN.PDF&quot;&gt;a representative SDS for Jet-A, courtesy of ConocoPhillips&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The fuel consists of medium-weight hydrocarbons, from C9 to C16&lt;/li&gt;&#xA;&lt;li&gt;The only specified aromatic component is napthalene, with a maximum concentration of 3%&lt;/li&gt;&#xA;&lt;li&gt;No additives (anti-static, FSII, anti-oxidation, biocidal) are specified -- these are generally variable from batch-to-batch, depending on the specific purchaser (a large airport might get to spec these directly with the refiner, while the small GA 'dromes are at the mercy of whoever pulls up in the fuel truck)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-12-09T05:22:05.213" LastActivityDate="2015-12-09T05:22:05.213" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23516" PostTypeId="1" AcceptedAnswerId="23540" CreationDate="2015-12-09T01:17:17.540" Score="2" ViewCount="2912" Body="&lt;p&gt;If an engine's horsepower is increased will max gross weight be increased?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example what is the effect on max gross weight of changing the engine on a small GA airplane from 65hp to 100hp.&lt;/p&gt;&#xA;" OwnerUserId="651" LastEditorUserId="1696" LastEditDate="2015-12-09T18:52:16.137" LastActivityDate="2015-12-12T01:13:59.223" Title="Does useful load increase with more horsepower?" Tags="&lt;aircraft-performance&gt;&lt;engine&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23517" PostTypeId="2" ParentId="23516" CreationDate="2015-12-09T01:30:05.537" Score="1" Body="&lt;p&gt;The short answer to your question is yes. However there are often other things involved than just increasing the horsepower (but anecdotally that has worked in the past). For example the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow&quot;&gt;Piper Cherokee line&lt;/a&gt; which goes from a 140HP all the way up through the Dakota which sports a 235HP engine on effectively the same airframe saw an increase in useful load as the horsepower increased (there were some aerodynamic changes that help over the years as well, like the swept wing that was introduced later). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a practical limit to this of course. First off there are engine size vs airframe limitations. For example you most likely can't bolt a &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Merlin&quot; rel=&quot;nofollow&quot;&gt;Merlin engine&lt;/a&gt; to a &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_J-3_Cub&quot; rel=&quot;nofollow&quot;&gt;Piper Cub&lt;/a&gt; frame (but I'm sure someone has considered it). There are also CG limits to take into account as your engine grows but airframe might not. CG loading can become an issue with very heavy engines up front. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some regards &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_loading&quot; rel=&quot;nofollow&quot;&gt;wing loading&lt;/a&gt; will come into play here. Since a bigger engine will help you overcome drag and fly faster you can generate more lift and thus lift more.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="4474" LastEditDate="2015-12-12T01:13:59.223" LastActivityDate="2015-12-12T01:13:59.223" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23518" PostTypeId="2" ParentId="23495" CreationDate="2015-12-09T02:37:51.183" Score="18" Body="&lt;p&gt;Not many jobs where you can kill hundreds of people or lose your entire career by making a simple mistake. And your every move is being recorded. Add to it that you're doing nearly the same thing over and over, but can't miss any tiny detail. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-12-09T02:37:51.183" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23519" PostTypeId="1" CreationDate="2015-12-09T05:10:20.760" Score="3" ViewCount="10998" Body="&lt;p&gt;If I'm a student pilot (for commercial), and I flew for pleasure with friends one night, do I log those hours as solo? Does solo mean, only &lt;strong&gt;pilot&lt;/strong&gt; in the aircraft? Or does it literally mean only person?&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="14897" LastEditDate="2021-05-06T22:56:12.153" LastActivityDate="2021-05-06T22:56:12.153" Title="What is the FAA definition of solo flight?" Tags="&lt;faa-regulations&gt;&lt;terminology&gt;&lt;solo-flight&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23520" PostTypeId="1" CreationDate="2015-12-09T05:12:40.973" Score="3" ViewCount="10241" Body="&lt;p&gt;Slip Skid Indicator as depicted in the picture below;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the significance of Slip Skid Indicator?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How Slip Skid Indicator is used in flying the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are other performance/operations needs to be taken care while this exceeds its normal bound?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r0gyl.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r0gyl.png&quot; alt=&quot;Primary flight display with Slip Skid Indicator, Source - www.aboutflight.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Primary flight display with Slip Skid Indicator, Source - www.aboutflight.com&lt;/p&gt;&#xA;" OwnerUserId="9966" LastEditorUserId="9966" LastEditDate="2015-12-09T05:18:09.013" LastActivityDate="2018-12-19T10:43:36.293" Title="What is the significance of Slip-Skid Indicator in PFD?" Tags="&lt;cockpit&gt;&lt;display&gt;&lt;skid&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23522" PostTypeId="2" ParentId="23519" CreationDate="2015-12-09T05:23:51.373" Score="10" Body="&lt;p&gt;According to FAA, it means that the pilot should be the only person in the aircraft. According to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.51&quot;&gt;14 CFR § 61.51 - Pilot logbooks&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) &lt;strong&gt;Logging of solo flight time.&lt;/strong&gt; Except for a student pilot performing the duties of pilot in command of an airship requiring more than one pilot flight crewmember, a pilot may log as solo flight time only that flight time when the pilot is the sole occupant of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.87&quot;&gt;14 CFR § 61.8761.87 - Solo requirements for student pilots&lt;/a&gt; also says pretty much the same thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;strong&gt;General.&lt;/strong&gt; A student pilot may not operate an aircraft in solo flight unless that student has met the requirements of this section. The term “solo flight” as used in this subpart means that flight time during which a student pilot is the sole occupant of the aircraft or that flight time during which the student performs the duties of a pilot in command of a gas balloon or an airship requiring more than one pilot flight crewmember.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-09T05:23:51.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23523" PostTypeId="2" ParentId="23520" CreationDate="2015-12-09T05:48:10.250" Score="2" Body="&lt;p&gt;According to &lt;a href=&quot;http://krepelka.com/fsweb/learningcenter/navigation/usingtheg1000.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page on using the G1000&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;Slip/Skid Indicator&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;The Slip/Skid Indicator is the small bar under the Roll Pointer. It moves away from the Roll Pointer to indicate slip or skid, just like&#xA;  the ball on a traditional Turn Coordinator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rpkgY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rpkgY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it's used exactly the same as the analog ball. If it's away from the roll pointer (out of center in analog), you're in a slip or a skid.&lt;/p&gt;&#xA;" OwnerUserId="4506" LastActivityDate="2015-12-09T05:48:10.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23524" PostTypeId="2" ParentId="23520" CreationDate="2015-12-09T06:13:44.073" Score="5" Body="&lt;p&gt;The slip/skid indicator is the small bar under the roll pointer. The image below should clarify that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/emgD8.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/emgD8.gif&quot; alt=&quot;slip/skid indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from flightlearnings.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Slip/Skid Indicator (sometimes called turn-and-bank indicator) moves left and right relative to the roll pointer in proportion to lateral acceleration and helps the pilot correct for any deviations in a turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a level flight, the indicator is centered. Assume that the pilot is executing a left turn (the roll pointer would've moved left)- if the indicator is in center, it means that the turn is coordinated i.e. the aircraft is not slipping or skidding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the indicator (bar) is moving right, it shows that the aircraft is skidding. Movement in the opposite side (i.e. towards the left, same direction of turn) indicates that the aircraft is slipping. This enables the pilot to take corrective action. This is one of the necessary flight instruments.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-09T06:13:44.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23527" PostTypeId="1" AcceptedAnswerId="23532" CreationDate="2015-12-09T09:03:28.433" Score="11" ViewCount="1132" Body="&lt;p&gt;How critical is it if a pebble blows into a propeller while taxiing and leaves a small abrasion in the leading edge? It wasn't noticed during flight and there was no apparent change in performance of the airplane, it was only noticed after parking. This is on a single engine piston aircraft.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-12-15T21:58:50.537" Title="How critical is it if a pebble blows into a propeller?" Tags="&lt;propeller&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23528" PostTypeId="2" ParentId="23512" CreationDate="2015-12-09T09:15:41.707" Score="2" Body="&lt;p&gt;Though performance details of the aircraft are not available, there seems to be a &lt;a href=&quot;http://www.avweb.com/avwebflash/news/ICON_Weight_Exemption_206991-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;significant weight penalty&lt;/a&gt; associated with making the aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/Spin_(aerodynamics)&quot; rel=&quot;nofollow noreferrer&quot;&gt;spin&lt;/a&gt; resistant.&lt;/p&gt;&#xA;&lt;p&gt;It appears that the aircraft had to get a &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0ahUKEwjVlo_Gt87JAhUEB44KHb9SDv8QFggcMAA&amp;amp;url=https%3A%2F%2Fwww.aopa.org%2F-%2Fmedia%2FFiles%2FAOPA%2FHome%2FNews%2FAll-News%2F2013%2FJuly%2FFAA_ICON_Decision.pdf&amp;amp;usg=AFQjCNHafoFXLGEKXXrd6PU2efIIWr0aWg&amp;amp;cad=rja&quot; rel=&quot;nofollow noreferrer&quot;&gt;specific exemption&lt;/a&gt; for increased &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;nofollow noreferrer&quot;&gt;MTOW&lt;/a&gt; (1680 lb as against 1430 allowed) due to the incorporation of spin resistant design. Note that the weight given by the manufacturer is 1510 lb, still more than allowed.&lt;/p&gt;&#xA;&lt;p&gt;As required in the exemption, the aircraft had to be fitted with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Ballistic_parachute&quot; rel=&quot;nofollow noreferrer&quot;&gt;ballistic recovery complete-aircraft parachute system&lt;/a&gt;, affecting the payload. The engine power is also limited to 135 hp. The range is also low (~300nm).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2956" LastEditDate="2020-07-22T11:07:14.057" LastActivityDate="2020-07-22T11:07:14.057" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23529" PostTypeId="1" AcceptedAnswerId="23531" CreationDate="2015-12-09T09:18:50.337" Score="8" ViewCount="2549" Body="&lt;p&gt;I was flying the other day by a military base and heard a military aircraft (I'm not sure what type it was) request a tactical penetration descent from the controller at a civilian airport. What is a tactical penetration descent?&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorDisplayName="user12485" LastEditDate="2015-12-09T11:12:26.067" LastActivityDate="2015-12-12T18:32:35.213" Title="What is a tactical penetration descent?" Tags="&lt;air-traffic-control&gt;&lt;military&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23530" PostTypeId="1" CreationDate="2015-12-09T09:26:18.520" Score="4" ViewCount="551" Body="&lt;p&gt;I will try to pose a well-structured question here on the longest routes ever or currently served by small, narrow-body airliners - specifically, the Boeing 737 and the Airbus A319 and A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Set aside special versions in the likes of the &lt;code&gt;Boeing 737-700BBJ&lt;/code&gt;, &lt;em&gt;what makes a small, narrow-body airliner serve routes that are longer than those on which it is usually deployed?&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is to say, what is added or changed, on the design side of things, to the structure or operability of planes that are not specifically designed for long distances, to make them capable of flying longer distances? I guess the answer is &lt;code&gt;ETOPS&lt;/code&gt;, but I am not sure of what this implies from the operational standpoint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For my moderate understanding it is quite impressive that narrow-body birds can fly from, say, Tokyo Narita to Mumbai - a distance of approximately 6,800 km or 4,220 mi (All Nippon Airways Boeing 737-700ER, flight NH829). Another example is Sunwing Airlines flight WG481 from Vancouver to Punta Cana (a Boeing 737-800 which flew for 5,930 km or 3,690 mi).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A list of such unusual performances can be seen &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-stop_flight&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11885" LastActivityDate="2018-10-17T23:28:58.087" Title="What changes do narrow-body airliners undergo to serve (relatively) long routes?" Tags="&lt;boeing-737&gt;&lt;airbus-a320&gt;&lt;etops&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23531" PostTypeId="2" ParentId="23529" CreationDate="2015-12-09T09:52:31.670" Score="10" Body="&lt;p&gt;According to &lt;a href=&quot;http://static.e-publishing.af.mil/production/1/440aw/publication/440awi11-250/440awi11-250.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;LOCAL FLYING OPERATING INSTRUCTION / 440 AIRLIFT WING INSTRUCTION 11-250 / OPR 440 OSS/OSA&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.7.4. ARRIVAL PROCEDURES:&lt;br&gt;&#xA;  5.7.4.1. DESCENTS:&lt;br&gt;&#xA;  5.7.4.1.1. TACTICAL (PENETRATION) DESCENT (Overhead, Downwind, Beam, etc): &lt;strong&gt;High rate (unrestricted) visual descent profile designed to transition an aircraft from a high-level altitude structure to a low-level altitude structure putting the aircraft in a safe position to execute a tactical approach.&lt;/strong&gt;&lt;br&gt;&#xA;  ...&lt;br&gt;&#xA;  5.7.4.1.3. TACTICAL (PENETRATION) DESCENT ASSAULT – High rate (unrestricted) visual descent profile designed to transition an aircraft from a high-level altitude structure to a low-level altitude structure putting the aircraft in a safe position to execute a tactical approach to an assault landing zone. Note: A separate penetration descent profile may also be flown to Mackall AAF (HFF), see Pope Aircrew In-flight guide for procedures.&lt;br&gt;&#xA;  5.7.4.1.3.1. Arrival Procedures:&lt;br&gt;&#xA;  5.7.4.1.3.1.1. When sequenced, commence penetration descent to a tactical approach, ARA, or normal pattern. Request desired approach as early as possible upon switching to Pope Tower.&lt;br&gt;&#xA;  5.7.4.1.3.1.2. Remain at or above 2500’ MSL until within 5 NM of Pope. Do not descend below 720’ MSL until given clearance to land from Pope Tower.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also fooot's &lt;a href=&quot;https://aviation.stackexchange.com/a/9580/12485&quot;&gt;answer&lt;/a&gt; to another question, where he describes a tactical descent as an extremely steep descent, and a tactical approach as an extremely steep approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to other sources, the technique in question might also be called (depending on the exact landing circumstances) an &lt;a href=&quot;https://www.reddit.com/r/aviation/comments/3cfwrp/fat_albert_25%C2%BA_steep_approach_from_the_cockpit/csvxugg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Assault Landing&lt;/a&gt;, a &lt;a href=&quot;https://www.reddit.com/r/aviation/comments/3cfwrp/fat_albert_25%C2%BA_steep_approach_from_the_cockpit/csvyj39&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sarajevo Approach&lt;/a&gt; or even a &lt;a href=&quot;http://www.airliners.net/aviation-forums/military/read.main/22331&quot; rel=&quot;nofollow noreferrer&quot;&gt;Khe Sanh Approach or an Overhead Approach&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-12-12T18:32:35.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23532" PostTypeId="2" ParentId="23527" CreationDate="2015-12-09T10:15:55.640" Score="11" Body="&lt;p&gt;This sort of FOD is often not an immediate problem, however introducing any slight knick or gouge to a propeller could be the beginning of a stress fracture. The last thing you want is a catastrophic prop failure whilst flying!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The correct course of action, much like any minor damage to the airframe, is to note it in the logs, have a mechanic look at it, and make the call if a repair is necessary.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2015-12-09T10:15:55.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23533" PostTypeId="1" AcceptedAnswerId="23570" CreationDate="2015-12-09T10:39:39.530" Score="4" ViewCount="311" Body="&lt;p&gt;How common is turbulence that is severe enough to feel uncomfortable? I don't mean a little shaking here and there, but a drop that lasts a second or two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last 2 flights I was on (Paris to Singapore, and Singapore to Sydney) had more than one big drop of turbulence, to the point where passengers screamed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this common? I know it is relatively safe, but feel uneasy about flying again as it was uncomfortable and scary!  &lt;/p&gt;&#xA;" OwnerUserId="12596" LastEditorUserId="62" LastEditDate="2015-12-10T02:15:37.307" LastActivityDate="2015-12-10T14:49:00.787" Title="Are most/all flights affected by a noticeable amount of turbulence?" Tags="&lt;turbulence&gt;&lt;wake-turbulence&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23534" PostTypeId="1" AcceptedAnswerId="23537" CreationDate="2015-12-09T10:48:09.000" Score="6" ViewCount="1272" Body="&lt;p&gt;It took me about 8 months to complete my PPL, because I struggled to go solo and I haven't started my CPL training yet due to financial set back. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard about students who completed their PPL training in 2 months. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible to complete PPL, CPL and Frozen ATPL in 12 months and how do you go about it? And also, are there any cases? The one I've seen is 18 months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the fact that you have to write CPL exams, ATPL exams, IR, Night Rating, 100 PIC hours and other related tasks.&lt;/p&gt;&#xA;" OwnerUserId="11492" LastEditorUserId="35166" LastEditDate="2020-04-17T00:54:21.163" LastActivityDate="2020-04-17T00:54:21.163" Title="Can PPL, CPL, and ATPL be completed within a year?" Tags="&lt;commercial-aviation&gt;&lt;flight-training&gt;&lt;general-aviation&gt;&lt;pilot-certification&gt;&lt;south-africa&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23535" PostTypeId="1" CreationDate="2015-12-09T10:48:51.580" Score="2" ViewCount="1302" Body="&lt;p&gt;Which compressed air and fluid are generally being used by oleo-struts? &lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2016-02-06T06:20:20.963" Title="Which compressed air and fluid are generally used by oleos?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23536" PostTypeId="2" ParentId="23533" CreationDate="2015-12-09T11:06:30.237" Score="1" Body="&lt;p&gt;Clear air turbulence (CAT) is associated with jet streams. Depending on the region, and even the season, CAT is common, and it can't be identified by weather radar, but the crew usually studies the weather chart before the flight, and can receive pieces of information from ground units, ATCOs and for aircraft leading them.&#xA;So, most of the times, they can be aware of CAT, but it can also disrupt the flights, as you could feel during your journeys.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-12-09T11:06:30.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23537" PostTypeId="2" ParentId="23534" CreationDate="2015-12-09T11:22:54.643" Score="7" Body="&lt;p&gt;Given the hours required for the ATP, the chance of doing that rating alone in under a year seems pretty remote.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Getting the private and commercial certificates done inside of a year is entirely possible, although not cheap. The writtens for the ATP are no big deal, but the hours simply will take a lot of time, as well as the right employment opportunity, to get.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number of FO's at smaller (regional) airlines who have been flying for several years but who don't yet have their ATP attests to the time required. You can (and generally have to) pay for the flight time to get your Commercial, but paying for all the flight time required for an ATP is simply beyond those of whose last name isn't Gates, Bezos, Trump, or etc.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-09T11:22:54.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23538" PostTypeId="2" ParentId="23527" CreationDate="2015-12-09T11:34:24.947" Score="1" Body="&lt;p&gt;Based on the description provided; it will have little aerodynamic (thrust, drag etc) effects, which is negligible and will not notice much in terms of performance.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;small abrasion in the leading edge&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After parking, maintenance guy has to check it up and take decision based on the impact, maximum allowed damage in propeller, repair availability in the current airport etc...&lt;/p&gt;&#xA;" OwnerUserId="9966" LastActivityDate="2015-12-09T11:34:24.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23539" PostTypeId="1" CreationDate="2015-12-09T14:02:24.527" Score="9" ViewCount="3267" Body="&lt;p&gt;From decades I have been reading that, fire services would spray foam on the runway, in order to avoid fire, on a belly landing. Is this procedure still being used? If not, what would be the safest procedure?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-12-09T18:35:37.733" Title="Do services still apply foam carpet on belly landings?" Tags="&lt;emergency-services&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23540" PostTypeId="2" ParentId="23516" CreationDate="2015-12-09T14:17:41.593" Score="4" Body="&lt;p&gt;That is a certification issue.  It depends on what limits the particular max gross weight for that aircraft.  If the design happens to be limited by the max weight that the landing gear can handle, then hanging a heavier engine with a high HP, would not change the max gross, but would decrease the max payload.&lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2015-12-09T14:17:41.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23541" PostTypeId="2" ParentId="23530" CreationDate="2015-12-09T14:38:04.130" Score="9" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;nofollow&quot;&gt;737 ER (Extended Range)&lt;/a&gt; differs from the rest of its family by having an extra fuel tank extending its effective range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Legally speaking (for US registered aircraft) you don't need to carry life preservers for each passenger, if you are only flying over land routes. So if a plane is being used for say a JFK $\rightarrow$ Nashville route, they would not be required to carry life preservers; but if they decided to use the plane on an over water route, they would have to outfit it as such. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inter-Country travel may also effect the outfitting of a plane, as various countries have different equipment requirements (although most are the same now). Long haul routes may very well translate to non domestic routes, which means the plane may need to be outfitted with extra equipment that is capable of working on foreign systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be some paperwork involved around certifications as well. &lt;a href=&quot;http://wireless.fcc.gov/services/index.htm?job=licensing&amp;amp;id=aircraft_stations&quot; rel=&quot;nofollow&quot;&gt;For example the FCC does not require domestically operated aircraft (commercial and GA) to have radio station licenses&lt;/a&gt;; however, it's often required by many foreign entities. A domestic only plane may need to obtain one of these licenses before heading to is destination.     &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a bit of a side note the pilot must also be familiar with the destinations' regulations and methods of operation. For example here is a &lt;a href=&quot;https://www.faa.gov/air_traffic/separation_standards/rvsm/documents/Pilot_Opr_Guidance_Mtrl_China_RVSM_2007101014251255.pdf&quot; rel=&quot;nofollow&quot;&gt;nice briefing from the FAA on flying into China&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="946" LastEditDate="2015-12-10T22:43:06.830" LastActivityDate="2015-12-10T22:43:06.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23542" PostTypeId="2" ParentId="23530" CreationDate="2015-12-09T15:04:24.563" Score="4" Body="&lt;p&gt;&lt;strong&gt;Why long routes by narrow bodies?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines use narrow bodies for medium-long range routes mainly for 3 reasons.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Demand&lt;/li&gt;&#xA;&lt;li&gt;Market strategy&lt;/li&gt;&#xA;&lt;li&gt;Fleet structure&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Demand&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines choose to service medium-long range route with narrow bodies simply because they don't have enough customers for bigger planes---like the 2 flights you have mentioned, both of them are cancelled because of insufficient demand.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Market strategy&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, some airlines are likely to provide more frequent services even with smaller planes. Business passengers are the main sources of income on those flights, they will pay extra for better a time that better suits them. That is common in flights between main cities between the east coast and west coast of the US. &lt;em&gt;American Airlines&lt;/em&gt; uses the 3-class A321 to service 10+ daily flights between JFK and LAX (2173 nmi).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, some airlines provide business-class exclusive services on the selected routes. Due to its relatively small demand, the airline will choose narrow bodies even for medium long route. &lt;em&gt;BA Clubworld&lt;/em&gt; between London city and JFK is such an example, they service the 3000 nmi route by A318 with 32 full flat bed seats.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fleet structure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines only operate narrow bodies, regardless of whether they are low cost carriers. So they service medium-long route only by narrow bodies, like Alaska 870 (Anchorage-Honolulu, 2418 nmi).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How long are routes by narrow bodies?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both A320 and B737 series have &quot;standard&quot; 3000+ nmi maximum range when fully loaded, which can cover most of the &quot;long&quot; route. More accurately their MOTW starts reducing when range is over 2000 nmi. (Except B737-700ER)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is hard to describe the payload/range in details. I would suggest you to have a look of it. (P.3-2-1 on &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A318_01_May_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A318&lt;/a&gt;, &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A319_May2014.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A319&lt;/a&gt;, &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A320_01_May_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320&lt;/a&gt;, &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC_A321_01_May_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A321&lt;/a&gt; &amp;amp; P.85-98 on &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;B737 series&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ETOPS stands for Extended-range Twin-engine Operational Performance Standards, a rule which permits twin engine aircraft to fly routes which, at some point, are more than 60 minutes flying time away from the nearest airport suitable for emergency landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ETOPS is not a must when flying &quot;long&quot; routes, but it is necessary when flying over oceans or close to the Pole. Due to the limitation of the range, only a few routes require ETOPS, including a few transatlantic route (UK/Iceland - US East Coast), US West coast to Hawaii, as well as East Asia to Micronesia/Melanesia.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="22726" LastEditDate="2018-10-17T23:28:58.087" LastActivityDate="2018-10-17T23:28:58.087" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23543" PostTypeId="1" AcceptedAnswerId="23549" CreationDate="2015-12-09T15:06:17.127" Score="6" ViewCount="19045" Body="&lt;p&gt;As highlighted by this &lt;a href=&quot;https://aviation.stackexchange.com/a/139/3394&quot;&gt;answer&lt;/a&gt; and by this &lt;a href=&quot;http://www.skybrary.aero/index.php/Hydraulic_Systems#Hydraulic_Pumps&quot; rel=&quot;nofollow noreferrer&quot;&gt;page&lt;/a&gt; the PTU (power transfer unit) is an hydraulic driven pump. It gets energy from one hydraulic system and uses it to pressurize another hydraulic system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What triggers the functioning of this pump? Is it automatic or manual? Is this pump available even if a leak is detected in the hydraulic system it tries to restore pressurisation to? &lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="15311" LastEditDate="2019-09-14T16:47:15.833" LastActivityDate="2019-09-14T16:47:15.833" Title="What triggers the PTU (Power Transfer Unit)?" Tags="&lt;aircraft-design&gt;&lt;hydraulic-system&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23544" PostTypeId="2" ParentId="23535" CreationDate="2015-12-09T15:12:27.580" Score="4" Body="&lt;p&gt;I'm sure it varies by aircraft type, but for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;C172S&lt;/a&gt; nose gear oleo (for example) it's air and hydraulic fluid. The operating handbook says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Keep strut filled with &lt;a href=&quot;https://en.wikipedia.org/wiki/Hydraulic_fluid#Specifications&quot; rel=&quot;nofollow&quot;&gt;MIL-H-5606&lt;/a&gt; hydraulic fluid per filling&#xA;  instructions placard, and with no load on the strut, inflate with air&#xA;  to 45.0 PSI&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-09T15:12:27.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23545" PostTypeId="2" ParentId="23534" CreationDate="2015-12-09T15:42:23.753" Score="3" Body="&lt;p&gt;Do you mean frozen ATPL? This can be easily done in 3 months if you have unlimited money and normal intellectual qualities.  &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2015-12-09T15:42:23.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23546" PostTypeId="2" ParentId="23504" CreationDate="2015-12-09T16:54:21.423" Score="10" Body="&lt;p&gt;The article in the Guardian said that they think they know who the owner is on paper, but that company isn't contactable.  Taking out advertisements in major newspapers (within the same jurisdiction, then covered as news by the world's press) is likely to be a step towards giving due notice before reposessions proceedings can start, to give the real owner time to respond.&lt;/p&gt;&#xA;" OwnerUserId="2559" LastActivityDate="2015-12-09T16:54:21.423" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23547" PostTypeId="2" ParentId="12747" CreationDate="2015-12-09T17:43:35.343" Score="-3" Body="&lt;p&gt;I am in a very similar situation as you. If you have ADD, my initial advice is &quot;good luck!&quot; My process went as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, I had to go to my doctor and asked to be officially taken off of the medication. Next, I went through a 90 day waiting period. During that 90 day waiting period, I met with my AME. Your AME must be HIMS certified. He gave me my physical and all other aspects of my health checked out. Out of pocket cost for physical and using him as my case manager was \$600. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the 90 days, I took my aviation neuro-psychological exam. This exam usually lasts 7-9 hours and insurance does not cover it. My out of pocket cost was \$2500. Within 24 hours of my neuro-psychological exam, I had to have a urine drug test done. This test must be done under direct observation; otherwise it is not valid. This only cost \$100. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;About a week and a half later, I met with a psychiatrist. This was about a three hour meeting that cost me \$550 out of pocket. This test was to determine my personality, check for alcoholism, depression, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, I was still not done after that. The way the neuro-psychological exam is set up is that if you don't do at least average on one section, then you need cognitive therapy. My scores were superior and high average on all but one section and I got the therapy recommendation. They gave me an IQ test in which I scored a 138. That's an exceptional IQ, but somehow I cannot pass this test. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right now I'm waiting for my AME's recommendation and my the psychiatrist results. Pretty sure I'll need therapy. I've been in flight school since July and my CFI has been ready to let me solo for months now. The whole process is pretty screwed up. Looking back, I should have kept my mouth shut.&lt;/p&gt;&#xA;" OwnerUserId="12604" LastEditorUserId="7348" LastEditDate="2016-03-23T15:30:12.183" LastActivityDate="2016-03-23T15:30:12.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23548" PostTypeId="2" ParentId="23539" CreationDate="2015-12-09T18:35:37.733" Score="6" Body="&lt;p&gt;Firefighting services &lt;a href=&quot;http://www.mumbaimirror.com/mumbai/others/Close-shave-MH192-was-prepared-for-belly-landing/articleshow/34068308.cms&quot;&gt;still apply foam path&lt;/a&gt;, atleast outside US, though the practice is no longer encouraged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA, in its 2002 &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/certalerts/&quot;&gt;CertAlert 02-04&lt;/a&gt; actively discourages it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA does not recommend the foaming of runways for emergency landings and warns against the practice with any foam other than “Protein” foam....  It is recommended that ARFF personnel decline to foam a runway when requested by a pilot because they do not have the specialized equipment and protein foam&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FAA lists a number of reasons for this decision (It had actually recommended foam paths for emergency landings in 1966, before withdrawing it in 1987), including,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Time may not be always available for foaming&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The use of foam in foam path should not affect the subsequent firefighting abilities.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Foaming the runway should not affect the movement and safety of other aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;ICAO too, does not recommend for foaming the runway in its &lt;a href=&quot;https://pkppksupadio.files.wordpress.com/2010/02/53391173-50953667-icao-airport-services-manual-part-1-rffs.pdf&quot;&gt;Airport Services Manual&lt;/a&gt;, stating,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;15.1.2 The effectiveness of runway foaming is not fully substantiated by the real evidence of operational incident studies.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ICAO also considers the various reasons for foaming the runway and analyses them:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a) &lt;strong&gt;Reduction in aircraft damage.&lt;/strong&gt; ... The data available from a study of emergency landings made with, and without, the application of foam show&#xA;  that no significant reduction is achieved in the risk of fire or in the extent of damage by the foaming of runways.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Reduction in deceleration forces.&lt;/strong&gt; ... It is to be noted that from what is&#xA;  known to date, the braking action of an aircraft on a foamed runway will only be slightly worse than that on a wet runway, assuming non-freezing weather.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Reduction in friction spark hazard.&lt;/strong&gt; ... tests have shown that aluminium alloy metals produce no friction sparks capable of igniting aircraft fuel vapours ... on either dry or foam-covered concrete or asphalt runway surfaces. ... Titanium friction sparks, capable of igniting aircraft fuel vapours, could not be effectively suppressed by runway foaming in any of the scale research tests ... &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Reduction in fuel spill fire hazard.&lt;/strong&gt; From all that is known of the fire suppression qualities of foam and the scale research tests, it is clear that a foamed runway would have no appreciable effect on the fire hazard of fuel vapours in the atmosphere over the foam.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;ICAO also points out that the primary firefighting vehicles should not be used for foam laying operations; Also, the time taken for the operations and replenishment is a concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is to be noted that, though the practice is no longer recommended, fire services are not barred from using it if the pilot asks for it and facilities are available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a related note, US armed forces &lt;a href=&quot;http://www.afmc.af.mil/news/story.asp?id=123461114&quot;&gt;seem to use it&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-09T18:35:37.733" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23549" PostTypeId="2" ParentId="23543" CreationDate="2015-12-09T19:20:32.660" Score="10" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PRHTp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PRHTp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(A320 PTU (Vickers), &lt;a href=&quot;http://www.eaton.com/ecm/idcplg?IdcService=GET_FILE&amp;amp;allowInterrupt=1&amp;amp;RevisionSelectionMethod=LatestReleased&amp;amp;noSaveAs=0&amp;amp;Rendition=Primary&amp;amp;dDocName=CT_195951&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Power Transfer Unit is well known on Airbus due to its barking-like sound (refresher: Video of a &lt;a href=&quot;https://www.youtube.com/watch?v=9ffJgk1-tCA&quot; rel=&quot;nofollow noreferrer&quot;&gt;PTU in action&lt;/a&gt;). The sound comes from a pump which creates a 3,000 psi pressure being quickly switched ON and OFF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zHJFL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zHJFL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://www.youtube.com/watch?v=hkAhaZL_9SM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Youtube&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU is a safety system to ensure hydraulic pressure is available, specially at takeoff, even if one or two hydraulic circuits have failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU can restore pressure in a deficient circuit without actually transferring fluid from the working circuit to the deficient one. This prevents throwing hydraulic fluid from the working circuit overboard if the deficient circuit is leaking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU is always activated, but is actually triggered based on a pressure differential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When is it activated?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Airbus A320 series, the PTU is actually the second source of pressure for the yellow and green hydraulic systems, after the EDP. It's always ON, ready for the pump activation if there is a pressure drop on the yellow or green hydraulic system and the differential pressure is more than 500 psi.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus A318, A319, A320 and A321 aeroplanes are equipped with three&#xA;  hydraulic systems and they can be safely controlled with only one&#xA;  system operative. A bi-directional PTU enables the yellow system to&#xA;  pressurize the green system, and vice versa, without the transfer of&#xA;  fluid from one system to the other.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In flight, the PTU operates&#xA;  automatically if a pressure drop in one of the systems is detected.&#xA;  The PTU ensures optimal hydraulic system availability for take-off.&lt;br&gt;&#xA;  &lt;sup&gt;&lt;br&gt;(Source: &lt;a href=&quot;http://ad.easa.europa.eu/blob/SIB_201216_R1_Airbus_SA_Hydraulic_System_Improvement.pdf/SIB_2012-16R1_1&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA safety bulletin&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Automatic inhibition below 1,500 ft in case of leakage&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU cannot restore the correct pressure in a circuit with a permanent leak. In this case, the PTU, and possibly the working hydraulic system, eventually overheat. The crew receives a failure &lt;em&gt;amber caution&lt;/em&gt; on the ECAM display and, up to recently, had to switch OFF (inhibit) the PTU manually to prevent damage.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In case of loss of hydraulic fluid of the yellow or green system, the PTU&#xA;  cannot pressurize the failed system and must be switched OFF as&#xA;  required by ECAM procedure to avoid a PTU overheat which may occur two&#xA;  minutes later.&lt;br&gt;&#xA;  &lt;sup&gt;&lt;br&gt;(Source: &lt;a href=&quot;http://ad.easa.europa.eu/blob/SIB_201216_R1_Airbus_SA_Hydraulic_System_Improvement.pdf/SIB_2012-16R1_1&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA safety bulletin&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tHhEe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tHhEe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;A320 PTU switch (source: &lt;a href=&quot;https://www.youtube.com/watch?v=uqKeSO6msDk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Baltic Aviation Academy&lt;/a&gt; which, by the way, has plenty of &lt;em&gt;quality&lt;/em&gt; training videos)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To avoid distraction from non-essential warnings during takeoff and landing, the ECAM message is not displayed when airborne below 1,500 ft height. There were several incidents (e.g. &lt;a href=&quot;https://www.gov.uk/aaib-reports/airbus-a319-111-airbus-g-ezdm-15-december-2008&quot; rel=&quot;nofollow noreferrer&quot;&gt;G-EZDM&lt;/a&gt;) where overheating became harmful before the amber ECAM message appeared at 1,500 ft, causing the temporary loss of a second system. Airbus added logic for automatic PTU inhibition when the aircraft is airborne, but still below 1,500 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The previous quotes are from an EASA bulletin related to this modification (also detailed in &lt;em&gt;&lt;a href=&quot;http://www.beca.be/magazines/safetyfirst/SafetyFirst-04.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Safety First&lt;/a&gt;&lt;/em&gt;, the Airbus safety magazine), with a failure scenario that had to be prevented:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jcuND.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jcuND.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Principle&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A PTU is connected to two independent hydraulic systems: The first to drive an hydraulic motor (or turbine) mechanically connected to a pump. The second hydraulic system is pressurized by the pump.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sYcxV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sYcxV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;PTU principle, &lt;a href=&quot;https://www.flightsim-corner.com/aller-plus-loin/737-800/circuit-hydraulique-b737-800/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PTU can be reversible (each hydraulic system can drive the motor or be pressurized by the pump) or not (the same system always drive the motor).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zI0MB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zI0MB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Actual PTU schematics, &lt;a href=&quot;http://www.eaton.com/Eaton/ProductsServices/Aerospace/Hydraulics/PCT_249171#tabs-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-09-13T13:10:09.277" LastActivityDate="2019-09-13T13:10:09.277" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23550" PostTypeId="2" ParentId="23543" CreationDate="2015-12-09T19:49:49.227" Score="5" Body="&lt;p&gt;Airbus A320 (also A319) has three hydraulic systems — green, yellow and blue. Green is driven by engine 1, while the yellow is driven by engine 2 (there are electric pumps for yellow and blue, but that's beside the point). The PTU is a bidirectional unit which enables the yellow system to pressurize the green and vice versa. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU runs automatically when the differential pressure between the green and yellow systems is more than 500 psi (normally, the system pressure is 3000 psi). The PTU (hydraulic) control/indicators in the overhead panel is shown in the following image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ak2hY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ak2hY.png&quot; alt=&quot;Hydraulic controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from A320 hydraulic manual&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PTU is inhibited during the first engine start and self tested when the second engine starts. During flight, the flight crew receive warnings for the following situations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Overheat in green/yellow reservoir.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Low air pressure in green/yellow reservoir.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Low fluid level in green/yellow reservoir (due to leak).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In these cases, the PTU will be inhibited automatically and will show a fault if it is still in AUTO mode, while the crew can take appropriate action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References: &lt;a href=&quot;http://www.smartcockpit.com/docs/A320-Hydraulic.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320 hydraulic Manual&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4474" LastEditDate="2015-12-11T01:32:23.313" LastActivityDate="2015-12-11T01:32:23.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23551" PostTypeId="2" ParentId="23402" CreationDate="2015-12-09T20:18:12.740" Score="10" Body="&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/a/1903/19&quot;&gt;answer&lt;/a&gt; you are referring to explains how radar is used to fly through a &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Squall_line&quot; rel=&quot;nofollow noreferrer&quot;&gt;squall line&lt;/a&gt; whilst avoiding the most turbulent areas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conventional weather radar cannot detect wind speed or turbulence directly, it only detects solid and liquid objects above a threshold size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most turbulent areas of thunderstorms are also those areas that contain the most water and ice. This precipitation reflects radar waves very well so the most turbulent areas have the strongest reflections and shows up as red / purple on the scope. The area downwind of the core is usually very turbulent as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the weather radar is merely detecting the presence of water. It is the pilot interpreting the picture who is really detecting the turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Clear-air_turbulence&quot; rel=&quot;nofollow noreferrer&quot;&gt;Clear air turbulence &lt;/a&gt; (CAT) does not have condensated water in it and is therefore undetectable by conventional radar. There are systems such as LIDAR that can detect CAT but they generally not installed on aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @reirab noted in a comment, a Doppler radar can be used to detect the relative speed of the particles from an aircraft. This is not used to reliably detect wind speed, but when there are large variations in wind speed (a.k.a. turbulence) the Doppler shift in the reflections from the particles causes a spectrum spread. This is an indication for turbulence. The traditional S-band airborne weather radars do not have this capability but the newer X-band radar (e.g. this &lt;a href=&quot;http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/BA_brochures-documents/Primus_880_Weather_Radar.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Honeywell radar (PDF)&lt;/a&gt;) can detect wet turbulence to distance of up to 40-60 nautical miles using this technique. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;LIDAR (a portmanteau of Light and RADAR) is a technology that uses light instead of radio waves. LIDAR can measure position and relative velocity of aerosols and therefore it can be used to detect turbulence. It has been used successfully to detect wind shears and map wake vortices on final approach from the ground (&lt;a href=&quot;https://www.wmo.int/pages/prog/www/IMOP/publications/IOM-109_TECO-2012/Session5/O5_06_Thobois_Scanning_Doppler_Lidar.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;paper&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-7615/year-all/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Currently investigation&lt;/a&gt; (&lt;a href=&quot;http://delicat.inoe.ro/files/DELICAT_ILRC25.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;paper&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;, &lt;a href=&quot;http://elib.dlr.de/91975/1/DELICAT_EASN_20141027_p.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;presentation&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt;)is going on into airborne use of LIDAR to detect CAT. One of the difficulty is to detect vertical components of the turbulence. This causes very little Doppler shift but at the same time have the most effect on the aircraft (since the vertical component of turbulence causes changes in angle of attack). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know there are currently no commercial applications of LIDAR for airborne turbulence detection. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-14T14:03:47.337" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="23554" PostTypeId="1" AcceptedAnswerId="23555" CreationDate="2015-12-09T22:15:28.733" Score="5" ViewCount="4995" Body="&lt;p&gt;I'm doing a manned aircraft design and make it easy to fly by making it hard to enter a pilot induced oscillation (PIO). I got a range of natural oscillation frequencies for my design in pitch, roll, and yaw, and now I'm trying to see if the period of these frequencies fall close or far away from most people's reaction time. I searched on Google, but only got data on twitch time, which doesn't seem applicable for an aircraft where some muscle power will be needed, hence my asking this question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My reasoning is that if it falls an order of magnitude below or above the reaction time of most pilots, the aircraft will be easy to fly (as long as it doesn't go through extreme high G maneuvers). An additional question I have related to this is, how can one design an aircraft to make it difficult for pilots to enter PIO's? &lt;/p&gt;&#xA;" OwnerUserId="11161" LastActivityDate="2015-12-09T22:32:58.373" Title="What is the typical reaction time for most pilots?" Tags="&lt;aerodynamics&gt;&lt;flight-controls&gt;&lt;stability&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23555" PostTypeId="2" ParentId="23554" CreationDate="2015-12-09T22:32:58.373" Score="3" Body="&lt;p&gt;Its a bit dated but here is a &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a178485.pdf&quot; rel=&quot;nofollow&quot;&gt;paper published by the Navy on visual reaction time you can find&lt;/a&gt;. Keep in mind these are navy pilots, often considered the best of the best and in peek physical condition. Based on the publish year I would suspect all subjects were male as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is &lt;a href=&quot;http://www.cti-home.com/wp-content/uploads/2014/01/Reaction-Time-and-Fatigue-Study.pdf&quot; rel=&quot;nofollow&quot;&gt;another study by NATO&lt;/a&gt; on reaction times for pilots on low sleep. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=3&amp;amp;ved=0ahUKEwjOp-216c_JAhVE6x4KHYQmCBQQFggsMAI&amp;amp;url=http%3A%2F%2Fwww.sajip.co.za%2Findex.php%2Fsajip%2Farticle%2Fdownload%2F53%2F51&amp;amp;usg=AFQjCNEsZ4Ii_VmFTBVKKc8NP2VnBae2Cg&amp;amp;sig2=LhM93Bv-k5UQdXLkXtxBKA&quot; rel=&quot;nofollow&quot;&gt;a nice study comparing the reaction times of pilots to non pilots&lt;/a&gt;, might be of some help. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An additional question I have related to this is, how can one design&#xA;  an aircraft to make it difficult for pilots to enter PIO's?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is an interesting question and in some regards could be its own question here. One of the big debates (mainly between Boeing and Airbus) is if systems like this should exist and who has the final say in terms of control deflection. Airbus takes the approach that the computers should prevent the pilot of say pulling back on the stick and stalling the plane. While Boeing generally allows pilots to be the final say and while their systems will warn of a stall you can ultimately pill back the column until the plane stalls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of how you would design something like this you would have to limit control input after an approach to oscillation was detected.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-12-09T22:32:58.373" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23556" PostTypeId="2" ParentId="23516" CreationDate="2015-12-09T23:08:42.017" Score="6" Body="&lt;p&gt;First, you ask one thing in the title and another in the text of your question. Useful load is the sum of fuel and payload, whereas the gross weight is the force produced by the mass of the whole aircraft in the gravitational field of Earth.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;First: Gross Weight&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If you change engine power during airplane design, gross weight will go up. At that point, you will have relative parameters like wing loading (kg/m²) and power loading (kW/kg) defined and will size the aircraft accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you switch the engine of an existing aircraft to a more powerful one, you will need to modify the airframe and systems if the aircraft had not been designed for the more powerful engine initially. Now your gross weight is already defined and cannot simply be changed. Let's first see what happens if a more powerful and heavier engine is fitted:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The higher engine mass will affect the location of the center of gravity and reduce the possible payload. Note that the mass increase will include a stronger engine mount and firewall, and possibly a balancing weight in the tail to put the center of gravity back into the legal range.&lt;/li&gt;&#xA;&lt;li&gt;If you want to maintain the same power loading, you will need to increase gross weight, which in turn will increase structural loads. Now you need a heavier structure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For now, let's assume that you stick with the old gross weight and reduce payload accordingly, because you do not want to rivet doublers all over the structure. Fine, but we are not done yet.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You might want to fit a larger propeller, which might require changes to the landing gear to keep a minimum ground clearance.&lt;/li&gt;&#xA;&lt;li&gt;Your minimum flight speed will go up. If the aircraft is certified according to FAR part 23, the minimum speed should stay below 61 knots (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_149&quot;&gt;§23.49(d)&lt;/a&gt;). Maybe you will need to fit more effective flaps to keep the minimum speed constant.&lt;/li&gt;&#xA;&lt;li&gt;Your maximum flight speed will go up. Technically, you can keep the limit speeds of the less powerful aircraft, but dive speed is calculated in one case by assuming 75% engine power (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_1335&quot;&gt;see §23.335(b)4i&lt;/a&gt;), so you will most likely be required to adjust limit speeds.&lt;/li&gt;&#xA;&lt;li&gt;Once you raise limit speeds, structural loads go up. Now you need again to start riveting doubles all over the place.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You see, you cannot legally escape. Fitting a more powerful engine will require adaptions in the structure, and once you need to reinforce wings, landing gear and fuselage, you can as well choose a higher gross weight. But now you need to re-size the structure and re-certify the modified aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And we have not even started to look at the systems:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The bigger engine will have a higher fuel flow. Are the fuel pumps adequate, or will you need to switch them for more powerful pumps?&lt;/li&gt;&#xA;&lt;li&gt;The higher design speeds might increase control forces, so now you need to modify the control system to avoid exceeding maximum stick forces (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_1143&quot;&gt;§23.143&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:1.0.1.3.10#se14.1.23_1175&quot;&gt;§23.175&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Will the new engine excite new harmonics somewhere in the aircraft? Maybe now a part will vibrate and shake itself to pieces which had stayed calm and in one before?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The list goes on, but this shall suffice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to your specific case: If you want to keep the power loading constant (which will give you the same performance as before), the airplane gross mass goes up by 54%, and so does the wing area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want more performance, you will need to reinforce the structure (or start all over with a new design of the same size), and now it is up to you which gross weight to pick. The heavier engine and structure will eat into your payload and fuel, but if you accept that limitation, you can fly with the same gross weight as before. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Second: Useful load&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As you can see from the first part of the answer, useful load is reduced by fitting a heavier and more powerful engine. Only when you re-work the structure to cope with the higher loads can you raise wing loading and regain the loss in useful load. Whether you can increase it by more than what you have lost so far depends on the maximum wing loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume for the rest of the answer that the outside shape (wing area, airfoil etc.) will stay identical to the original aircraft, except for maybe a bigger cowling, propeller and radiator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mass increase of the power plant plus its supporting structure is linear to the increase in performance. To beef up the structure, you could use the same percentage rule to stay on the safe side, but the real increase will be smaller. There are &lt;a href=&quot;https://shop.darcorp.com/index.php?route=product/product&amp;amp;product_id=78&quot;&gt;books which list parametric formulas for airplane masses&lt;/a&gt;, and those will show you the influence of the main parameters. They show that wing mass goes up with the square root of dive speed. Since speed is proportional to the third root of engine power, you will see that 54% more power means 15.5% more speed and 7.5% more structural mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's assume that the propulsion system is 15% of the aircraft mass, and structural mass is another 40%. Your empty mass will go up by 8% (engine) and 3% (structure), and if your useful load was 30% of gross weight before, it will now be down to 19% of the same mass. Now we need to bump up the gross mass, and go for half of what you would gain if you keep power loading constant. This means your gross mass is going up to 127% of the original gross mass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before you rejoice that now your useful load has gone up to 46%, we need to account for the additional structural reinforcement that this gross mass increase produces. The parametric formulas give a structural mass increase proportional to m$_{gross}^{0.3}$ for the fuselage and m$_{gross}^{0.7}$ for the wing, and a higher wing loading will again result in a dive speed increase, so your total structure will now maybe weigh 15% more than before, for a total of 47% or 48% of the initial gross mass. Yes, your structural mass fraction will go up when you  increase wing loading! But still a sizable increase in useful mass should remain - you will now have 39% or 40% of the original gross mass available for fuel and payload, for a relative increase of 30% over the original useful load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I never tried to keep minimum speed constant, but that would had complicated this answer even more. If the original plane had no or very simple flaps, this would be quite feasible, but result in almost a new wing design.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-10T08:26:00.983" LastActivityDate="2015-12-10T08:26:00.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23558" PostTypeId="2" ParentId="23495" CreationDate="2015-12-10T02:41:23.027" Score="42" Body="&lt;p&gt;The amount, types, duration, and severity of pilot stressors vary widely. The individual airline, union involvement, scheduled versus non-scheduled, international or domestic, type of equipment, freight or passengers, everything has an effect. I look at pilot stress within the context of what I was doing the last 10 years of flying 747s on international routes for two carriers. For me, the stressors usually (but certainly not always) were of three types: physical abuse of the body, decision making in the face of incomplete information, and frustration over things I had little or no control of. The examples below are from the 1990s, but I'm reasonably certain like things and conditions still occur. There are still 747-200s flying, not many, but two of them are SAM 28000 and SAM 29000, the President's two 747s (heavily modified of course).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Physical Abuse of the Body&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For me the biggest stressor was the massive time zone changes. The last five years I was based out of JFK, but I lived in Oregon. After I collected a little seniority, I typically had 12 days off in a row each month, but a day of that on each end was given over to commuting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus a work period began with the hassle and uncertainty of jumpseating for a multiple leg, minimum 2500 mile journey and a 3-hour time zone change to JFK. The most typical next day was JFK to Tel Aviv, a 12 hour flight and another 7-hour time zone change. We left JFK in late evening, arrived at the hotel in Tel Aviv in early evening of the next day. I would wake up in Tel Aviv around 0200 local, and from that point on through the rest of the work period, my circadian rhythm was totally screwed up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We did a lot of charters, and that introduced a great deal of irregularity into our schedules. It was not uncommon to have a charter come up that would take us off the line that we bid for and was awarded, and from that point on we usually did not get back to the awarded line. Thus we often would not know what we would be doing after we completed the current flight until we got the call in the hotel after the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you operate often into third word countries, you may occasionally get sick. It happened to me twice in 10 years, once in Jakarta at the Hilton, and once in the Ramada just off the airport in Delhi. The Jakarta Hilton had a 24/7 clinic in the basement, primarily for their employees but available to their guests, so it was no big deal to have a doctor come up to my room in the middle of the night and give me a shot to control the vomitting and diarrhea and stop the dehydration. The Ramada was a much smaller hotel, so they had to call out a doctor from home, again in the middle of the night. We had no reserve captains in Delhi. I operated a Hajj flight the next day with a hand towel arranged as a diaper.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Decision Making in the Face of Incomplete Information&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This happened all the time. It was part of the job, took many forms, and meeting the challenges was part of the fun, but it was stressful. For example, we picked up a planeload of U.S. Army troops at Stewart Air National Guard Base in New York to take to a recently constructed runway in the Balkans. We fuel-stopped in Paris because we had to have enough fuel to get out of where we were going. There was no fuel there. There turned out to be, in fact, nothing there but a very narrow, short (for a 747) runway surrounded by farmland, no buldings save for a couple of construction trailers. I wasn't given the information for the destination until just before departure in Paris. Enroute from Paris, looking at the approach plate and runway data, I saw two problems. The destination weather was forecast to be overcast, but with the ceiling high enough that we would be able to get in using the only approach aid available, an NDB. However, the airplane we had been dispatched with had an ADF that had only a pointer bug rather than a full needle. Our ops specs prohibited NDB approaches without a pointer needle with a tail. I ignored that problem. The second problem was that the taxi chart showed a runway too narrow to turn around on without getting a wing gear off the edge. There were no taxiways, no turnarounds, no ramps. This caused a series of contacts on HF via Stockholm Radio (no Satcom on this old airplane) between myself, dispatch, and our director of operations. The final call from the DO was to tell me he had talked to the military and that though the airport plate didn't show it, there was now a small ramp at each end of the runway. We landed, unloaded, and departed without incident.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Frustration Over Things I Couldn't Control&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;This category was large, most minor, some laughable even, some of more consequence, but all for me irritating. Things like being lied to by ground support people, crappy accommodations (I and a flight engineer got body lice from a stay at the Hotel Carrera in Santiago, Chile), having to pay bribes (especially in Indonesia and Egypt), having to sometimes wait hours for immigration clearance, often having to first say &quot;salaam alaikum&quot; on initial contact with Saudi Arabian controllers before they would answer , having to switch back and forth between saying Bombay or Mumbai during the name switch. Hindu nationalist controllers wouldn't answer unless you said Mumbai, others wouldn't answer unless you said Bombay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident I most remember in this category is when I, a first officer, a flight engineer, and 14 flight attendants commercialled to Medina, Saudi Arabia to pick up a flight. After we got there, we were told the airplane was going to be at least 12 hours late. No problem, hotel time, as the rule was we were entitled to a room if there was to be more than a five hour delay. However, problem, there were no available accommodations in the airport area. There were rooms available in the city but, like Mecca, non-muslims cannot enter Medina. We sat for 14 hours in a terminal with pathetic air conditioning in the middle of summer before the airplane arrived.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One final small irritant. We kept having to give up our usual parking area at Tel Aviv to SAM 28000 and SAM 29000 during the latter months of Bill Clinton's time in office as he was making last ditch efforts to broker an Israeli-Palestinian peace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, stressful, definitely, but it was the highlight of my life, and I'm glad I did it all, including all that wasn't so great at the time.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-12-10T15:29:44.253" LastActivityDate="2015-12-10T15:29:44.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23560" PostTypeId="1" CreationDate="2015-12-10T03:58:06.347" Score="2" ViewCount="1809" Body="&lt;p&gt;I'm trying to better my understanding of the physics behind gyroscopic instruments in an aircraft. I am aware that a spinning gyroscope creates rigidity in space by resisting applied forces. But, what exactly is the resistive force acting on the externally applied to forces, and how is it created? Is that what precession is? &lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="595" LastEditDate="2015-12-10T07:47:18.780" LastActivityDate="2015-12-10T07:47:18.780" Title="How do gyroscopic instruments work?" Tags="&lt;aircraft-physics&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ClosedDate="2015-12-10T08:47:29.737" ContentLicense="CC BY-SA 3.0" />
  <row Id="23561" PostTypeId="2" ParentId="23560" CreationDate="2015-12-10T05:16:24.727" Score="0" Body="&lt;p&gt;I saw this pretty cool video a while ago:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/TUgwaKebHTs?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It gives an intuitive discussion of gyroscopes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On another level though, it boils down to the angular momentum of the spinning gyroscope, and the fact that in order to change that momentum's direction/magnitude, an external moment must be applied.&lt;/p&gt;&#xA;" OwnerUserId="12551" LastActivityDate="2015-12-10T05:16:24.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23562" PostTypeId="2" ParentId="23560" CreationDate="2015-12-10T06:46:22.517" Score="0" Body="&lt;p&gt;Gyroscopes basically work by the principle of conservation of angular momentum. Consider a gyroscope (or a spinning wheel) in space like shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FDRKm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FDRKm.png&quot; alt=&quot;Gyrospcpe&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from pigeonsnest.co.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider the wheel in the center spinning at an angular velocity $\omega$, so that the spin angular momentum is $I\omega$, along the X axis. Now, consider a torque applied $\mathcal{T}$ along the Z axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the resultant of these two makes the spin axis to align along the axis A'. Basically, the spin angular momentum 'chases' the torque in the same plane. This is the basis of gyroscopic precession.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See Prof. Walter Lewin's lecture on &lt;a href=&quot;https://www.youtube.com/watch?v=N92FYHHT1qM&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolling motion and gyroscopes&lt;/a&gt; for a thorough explanation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-10T06:46:22.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23563" PostTypeId="1" AcceptedAnswerId="23564" CreationDate="2015-12-10T07:03:27.070" Score="8" ViewCount="1612" Body="&lt;p&gt;It seems the 737-200 had an issue with separation of engines from the wings. Considering that the engines are mounted completely under the wings, there should be more attaching points than a modern jet engine the question is why is this aircraft so prone to this sort of incident? Is it something to do with the airflow and the forces associated to it? Or is it purely a manufacturing defect?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &#xA;&lt;a href=&quot;https://www.flightglobal.com/news/articles/nationwide-737-engine-loss-inquiry-finds-fatigue-crack-in-mount-220017/&quot;&gt;https://www.flightglobal.com/news/articles/nationwide-737-engine-loss-inquiry-finds-fatigue-crack-in-mount-220017/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Snippet from the article: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fatigue failure of aft cone bolts has been attributed to a number of&#xA;  engine-separation incidents involving 737-200s – among them a US Air&#xA;  aircraft at Deptford in December 1987, a United Airlines jet at&#xA;  Chicago in January 1989, and a Delta Air Lines aircraft at Dallas in&#xA;  January 1992. All three lost their right-hand engines on take-off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2015-12-10T07:09:39.350" LastActivityDate="2015-12-15T02:20:56.620" Title="Why are 737-200 engines more susceptible to separation?" Tags="&lt;boeing-737&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23564" PostTypeId="2" ParentId="23563" CreationDate="2015-12-10T07:46:37.383" Score="11" Body="&lt;p&gt;In general, jet engines are mounted under wings using only a few attachment points- Boeing uses cone pins in 737-100s and 200s (these were changed into fuse pins from 737-300s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older 737s with cone pins (the SA 737 is a 200) has a history of failure and almost all the the cases being blamed on the fatigue and manufacturing defect of the aft bolt (which usually resulted in over-stressing and failure of the two front bolts). I've just listed some of the incidents and the probable causes (from NTSB):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incident: January 03, 1986 involving BOEING 737-2H4, registration: N86SW &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Probable Cause: ...EXAMINATION OF THE CONE BOLT REVEALED THAT IT FAILED AS A RESULT OF FATIGUE, MOST PROBABLY DUE TO IMPROPER INSTALLATION OF THE BOLT, SPECIFICALLY, THAT IT WAS UNDER TORQUED WHEN THE OPERATOR RE-INSTALLED THE ENG.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Incident: December 05, 1987 involving BOEING 737-2B7, registration: N319AU &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Probable Cause:  ... THE AFT MOUNT CONE BOLT FOR THE #2 ENG HAD FAILED FM FATIGUE THRU THE THREAD RELIEF UNDERCUT RADIUS. FATIGUE CRACKS HAD INITIATED ON DIAMETRICALLY OPPOSITE SIDES OF THE RADIUS. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Incident: January 20, 1989 involving BOEING 737-201, registration: N242US&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Probable Cause: PREVIOUS DAMAGE TO THE AFT CONE (ENGINE MOUNTING) BOLT, WHICH RESULTED IN MISMATCHED SURFACES BETWEEN THE BOLT AND ISOLATION MOUNT, LOSS OF TORQUE DURING CYCLIC LOADING OF THE MOUNTING BOLT, AND SUBSEQUENT FATIGUE FAILURE OF THE BOLT&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Incident: January 07, 1992 involving BOEING 737-232, registration: N322DL &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Probable Cause: THE FAILURE OF THE AFT CONE BOLT AS RESULT OF PREEXISTING FATIGUE CRACKING DUE TO IMPROPER MAINTENANCE, AND THE FAILURE OF THE SECONDARY SUPPORT STRUCTURE AS A RESULT OF LOADS THAT EXCEEDED THE CAPACITY OF THE ATTACHING HARDWARE AND THE CRUSHABLE HONEYCOMB CORE. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The incident involving the Nationwide 737-230 was also &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20071107-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;traced back to fatigue of the engine bolt&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The right-hand engine separated from the aircraft due to the failure of the aft cone bolt as a result of a pre-existing fatigue crack which was most likely caused by incorrect installation of the cone bolt. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No investigation has pointed to any problem with the airflow or associated forces. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In a related note, 747s, which use fuse pins also had a number of incidents/accidents caused due to failure of the pins and &lt;a href=&quot;https://aviation.stackexchange.com/a/23155/9731&quot;&gt;Boeing changed the design&lt;/a&gt; quite a few times.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-12-10T07:46:37.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23565" PostTypeId="1" CreationDate="2015-12-10T09:43:05.103" Score="17" ViewCount="4115" Body="&lt;p&gt;I have noticed on all Airbus of the A320 series that I have flown as a passenger (which includes the 319, the 320 and the 321), that whilst in level flight, the aircraft has always a longitudinal axis rocking motion. It is very low but if you focus on the horizon from the window you can actually notice the aircraft rocking left and right. Almost not perceivable but it is actually there! This does not happen on the A330's or A340's&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any particular reason for this type of behaviour?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2015-12-10T19:17:20.200" LastActivityDate="2019-05-13T10:05:53.557" Title="Why does the Airbus A320 series seem to rock left and right in level flight?" Tags="&lt;airbus-a320&gt;&lt;stability&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23566" PostTypeId="1" AcceptedAnswerId="23567" CreationDate="2015-12-10T12:34:34.680" Score="5" ViewCount="1437" Body="&lt;p&gt;When I was reading about the &lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;nofollow noreferrer&quot;&gt;HAL Tejas&lt;/a&gt; I observed that it was described as a &quot;tailless&quot; plane. However I could see a tail in &lt;a href=&quot;https://en.wikipedia.org/wiki/HAL_Tejas&quot; rel=&quot;nofollow noreferrer&quot;&gt;the picture&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After careful reading I am assuming that being tailless means not having any tail planes a.k.a horizontal stabilizers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does tailless means no tail at all?&lt;/p&gt;&#xA;" OwnerUserId="8004" LastEditorUserId="3201" LastEditDate="2017-07-27T20:03:31.213" LastActivityDate="2019-11-28T13:08:46.377" Title="Does tailless means no tail at all?" Tags="&lt;terminology&gt;&lt;delta-wing&gt;&lt;tail&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23567" PostTypeId="2" ParentId="23566" CreationDate="2015-12-10T12:56:21.723" Score="6" Body="&lt;p&gt;No, not at all - there are at least two Delta Wing aircraft that feature a conventional tail, and they are the Gloster Javelin and the Mig 21&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gloster_Javelin&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Gloster_Javelin&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VmBA8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VmBA8.jpg&quot; alt=&quot;Gloster Javelin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VRVGq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VRVGq.jpg&quot; alt=&quot;Mig-21&quot;&gt;&lt;/a&gt;&#xA;(Courtesy of &lt;a href=&quot;http://airheadsfly.com/&quot; rel=&quot;noreferrer&quot;&gt;http://airheadsfly.com/&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition (and I believe this is within the spirit of what you've asked) you then you have aircraft such as the Eurofighter Typhoon or Saab 37 Viggen which feature canards:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/kY7ZA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kY7ZA.jpg&quot; alt=&quot;Eurofighter Typhoon&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_37_Viggen&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Saab_37_Viggen&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Lc7Y5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lc7Y5.jpg&quot; alt=&quot;Saab 37 Viggen&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, &quot;Delta&quot; only describes the wing shape - though there of course features of the shape that will lead to many designs appearing similar. The Wikipedia article has a nice infographic showing the general variations of Delta Winged designs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Delta_wing&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Delta_wing&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Vzc8K.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vzc8K.png&quot; alt=&quot;Delta Wing Layouts&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2015-12-10T12:56:21.723" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23568" PostTypeId="2" ParentId="23566" CreationDate="2015-12-10T13:50:45.303" Score="18" Body="&lt;p&gt;Tailless means no horizontal tail, but a vertical tail is still allowed. Examples are the &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F-102_Delta_Dagger&quot; rel=&quot;noreferrer&quot;&gt;Convair F-102&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_B-58_Hustler&quot; rel=&quot;noreferrer&quot;&gt;Convair B-58&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YY0Wg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YY0Wg.jpg&quot; alt=&quot;Convair B-58 Hustler&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Convair B-58 Hustler (picture &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:B-58_Hustler.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this to a flying wing: Here even the vertical tail is left off. Since a classic delta would have too little lever arm for yaw control, this requires a higher aspect ratio wing. An example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Horten_Ho_229&quot; rel=&quot;noreferrer&quot;&gt;Horten IX&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GQ0uA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GQ0uA.jpg&quot; alt=&quot;Horten IX V1 prototype aircraft&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horten IX V1 prototype aircraft (picture &lt;a href=&quot;http://jpcolliat.free.fr/ho9/images/ho9v1_13.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-10T13:50:45.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23569" PostTypeId="1" CreationDate="2015-12-10T14:03:54.517" Score="1" ViewCount="202" Body="&lt;p&gt;Is there a qualitative difference for landing fees/charges between charter and scheduled flights at a particular airport?&lt;/p&gt;&#xA;" OwnerUserId="12616" LastEditorUserId="1696" LastEditDate="2015-12-10T15:25:48.630" LastActivityDate="2015-12-10T18:58:12.800" Title="Is there a difference in landing fees for charter and scheduled flights?" Tags="&lt;airline-operations&gt;&lt;cost&gt;&lt;landing-fees&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-11T01:33:22.977" ContentLicense="CC BY-SA 3.0" />
  <row Id="23570" PostTypeId="2" ParentId="23533" CreationDate="2015-12-10T14:49:00.787" Score="3" Body="&lt;p&gt;It's very difficult to answer this question as it depends upon so many different things:&#xA; - Location&#xA; - Time of day&#xA; - Season&#xA; - Flight level&#xA; - Terrain below&#xA; - Current weather (of course)&#xA; - Type of aircraft&#xA; - The crew and their knowledge / weather radar use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What also makes it hard is that what 'feels uncomfortable' for one person might not for another.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the tropics it's quite common for flights to be affected by turbulence. Most will see at least some light chop. In my experience of a few hundred long-haul flights through the tropics I've only had a couple with no moderate turbulence (what you might call uncomfortable). In a similar number of short-haul flights in Europe I'd say that around 50% had no significant turbulence at all and only around 5% had moderate turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You're more likely to experience turbulence in the tropics as there's a lot more convective activity there (air rising and falling). Away from the tropics the USA tends to generate turbulence whilst Europe does not (relatively speaking). SE Asia is particularly well known for turbulence encounters.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2015-12-10T14:49:00.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23571" PostTypeId="1" CreationDate="2015-12-10T16:05:47.817" Score="9" ViewCount="616" Body="&lt;p&gt;I'll try to make this question a little more manageable by applying the following constraints, though of course all answers would be welcome:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;By &quot;General Aviation / Training&quot; aircraft, I'm talking primarily about normal SEP's of the kind that we see daily and would require no more than a check-ride before hiring. No experimentals, warbirds, super rare aircraft etc - though MEP's and Complex Aircraft would count.&lt;/li&gt;&#xA;&lt;li&gt;I'm ignoring low level maneuvers. We all know a stall at 100ft is going to be tricky, though on the other hand, if something is going to require 5000' at a minimum to recover from then that's going to be fatal in most cases.&lt;/li&gt;&#xA;&lt;li&gt;Let's ignore mechanical and airframe failures that occur prior to the incident.&lt;/li&gt;&#xA;&lt;li&gt;I'm assuming Weight &amp;amp; Balance are within the normal category of the POH (As opposed to utility or aerobatic).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Beyond that, the question is what it says on the tin. Is there anything stupid that I can do as a Pilot in a Single Engined Piston GA aircraft that I simply won't be able to recover from, even with a few thousand feet to do so?&lt;/p&gt;&#xA;" OwnerUserId="2160" LastEditorUserId="7532" LastEditDate="2015-12-12T17:06:21.077" LastActivityDate="2019-01-05T13:05:53.737" Title="Are there any manoeuvres that would be considered unrecoverable in a General Aviation / Training Aircraft?" Tags="&lt;flight-training&gt;&lt;pilot-technique&gt;" AnswerCount="5" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23572" PostTypeId="2" ParentId="23571" CreationDate="2015-12-10T16:23:08.993" Score="6" Body="&lt;p&gt;The two most common training aircraft out there are the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;noreferrer&quot;&gt;Piper Cherokee (numerous variants)&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;noreferrer&quot;&gt;Cessna 172/152 (numerous variants as well)&lt;/a&gt;. The cherokee is not spin certified and the 172 is only spin certified in the utility category so I would not try spinning either frankly. Technically you may be able to recover from a spin with enough altitude and depending on the situation but a pilot could get them selves into a nasty situation by spinning either plane. Even regular stalls put you at risk of entering a spin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lots of maneuvers (aerobatic mainly) that would kill the engine on many common GA planes. Generally speaking the oil systems are not built for inverted maneuvers or anything that would starve the oil pump. The Cessna also has a gravity fed fuel system which would not do to well inverted. In regards to stalling the engine and recovering while you may be able to glide down to a field if an engine is lost this is more in reference to losing an engine during a maneuver and having insufficient thrust to recover properly from the maneuver.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would think that you might also be able to get the plane into an aggressive dive that might be hard to recover from for an untrained pilot. At some point the recovery will exceed the load the wings can handle as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here in the US the FAA requires knowledge of spin awareness and what may cause a plane to enter a spin but there is no requirement to demonstrate a spin for a basic private pilots license nor is there a requirement for them to be demonstrated to the student.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-10T18:48:15.513" LastActivityDate="2015-12-10T18:48:15.513" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23573" PostTypeId="1" CreationDate="2015-12-10T17:36:02.937" Score="2" ViewCount="474" Body="&lt;p&gt;I have a dual orfice fuel nozzle (Used in CFM56 Engine/ Parker make). The secondary orifice is not opening up even at the required injection pressure. It had been not used for 3 years and I assume that it is clogged. Please suggest a method to clean this. &lt;/p&gt;&#xA;" OwnerUserId="12620" LastEditorUserId="19" LastEditDate="2017-08-10T09:58:47.693" LastActivityDate="2017-08-10T09:58:47.693" Title="How to remove clogging in aircraft fuel nozzles?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23574" PostTypeId="2" ParentId="23569" CreationDate="2015-12-10T18:11:19.887" Score="3" Body="&lt;p&gt;This is almost completely dependent on the airport but we can talk somewhat generally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth airlines (scheduled carriers) can often negotiate lower landing fees by being able to guarantee a specific amount of flights into an airport. Charter companies don't have this luxury since it can be hard for them to predict where and when they are going. On the other hand some fees are set by the local government, for example here in Philadelphia any airport in the city (KPHL and KPNE) has landing fees set by the city. You can find the &lt;a href=&quot;http://www.phl.org/Business/GeneralAviation/PhiladelphiaNortheastAirport/Documents/PNEApenndixH.pdf&quot; rel=&quot;nofollow&quot;&gt;official legislation here&lt;/a&gt; and I assume thats non negotiable but I cant be sure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a bit of a discrepancy due to the type of planes. Landing fees are often charged by weight and in most cases charter planes are flying smaller stuff than the scheduled carriers and their fees may be lower as a result (even though the scheduled carrier has a lower rate). If we look &lt;a href=&quot;http://www.phl.org/Business/GeneralAviation/PhiladelphiaNortheastAirport/Documents/PNEApenndixH.pdf&quot; rel=&quot;nofollow&quot;&gt;again at Philadelphia&lt;/a&gt; we can see that they have fees for both weight and passengers which generally go hand in hand however a charter company may be flying a big RJ for just one guy while a scheduled carrier may be operating the same plane at its maximum seating arrangement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Charter carriers may also have the luxury of flying into smaller satellite airports where the fees may be lower or structured differently. Since some of these airports could potentially be private or private/public they have the ability to charge what they chose. Some will even have no fee if you buy a pre prescribed amount of fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For other points of reference you can check out the &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.panynj.gov/airports/pdf/scheduleofcharges-ewr.pdf&quot; rel=&quot;nofollow&quot;&gt;New York Landing Fees&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.miami-airport.com/pdfdoc/Fees_and_Charges_Book.pdf&quot; rel=&quot;nofollow&quot;&gt;Miami Landing Fees&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-10T18:58:12.800" LastActivityDate="2015-12-10T18:58:12.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23575" PostTypeId="2" ParentId="23571" CreationDate="2015-12-10T18:30:39.823" Score="9" Body="&lt;p&gt;Yes, easily. Just fly fast enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you deflect a control surface fully at a speed above $v_A$, the risk of a structural failure is very real. After all, at $v_D$ only a third of the mechanically possible deflection is allowed (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=c76256a3bf5f0d099a7d6e750d294532&amp;amp;mc=true&amp;amp;n=pt14.1.23&amp;amp;r=PART&amp;amp;ty=HTML#se14.1.23_1441&quot; rel=&quot;noreferrer&quot;&gt;§23.441&lt;/a&gt; for the rudder and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=c76256a3bf5f0d099a7d6e750d294532&amp;amp;mc=true&amp;amp;n=pt14.1.23&amp;amp;r=PART&amp;amp;ty=HTML#se14.1.23_1455&quot; rel=&quot;noreferrer&quot;&gt;§23.455&lt;/a&gt; for the ailerons). Even combining full deflections of more than one control surface at $v_A$ is not covered, as is a &lt;a href=&quot;https://en.wikipedia.org/wiki/American_Airlines_Flight_587&quot; rel=&quot;noreferrer&quot;&gt;repeated deflection in sync with rigid body oscillations&lt;/a&gt; which can create excessive loads. For a definition of the design speeds, see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=c76256a3bf5f0d099a7d6e750d294532&amp;amp;mc=true&amp;amp;n=pt14.1.23&amp;amp;r=PART&amp;amp;ty=HTML#se14.1.23_1335&quot; rel=&quot;noreferrer&quot;&gt;§23.335&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulations require minimum control forces so the pilot feels when he/she overstresses the airframe, but they are still within the strength of a normal adult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if you fly too fast in gusty weather, you can overload the structure. This is rare because the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=c76256a3bf5f0d099a7d6e750d294532&amp;amp;mc=true&amp;amp;r=SECTION&amp;amp;n=se14.1.23_1333&quot; rel=&quot;noreferrer&quot;&gt;25ft/s gusts&lt;/a&gt; which must be tolerated up to $v_D$ are quite uncomfortable to fly through.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-12T09:28:37.810" LastActivityDate="2015-12-12T09:28:37.810" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23576" PostTypeId="2" ParentId="23519" CreationDate="2015-12-10T21:50:02.053" Score="-4" Body="&lt;p&gt;I am assuming you have a Private Pilot's certification? &lt;p&gt;&#xA;(SEL or MEL etc. does not matter as long as you are type rated and certified to fly the airplane you going to go fly in with your friends) &lt;p&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, technically this flight of yours goes in your log book as just another regular flight. Can you count hours towards another certification (towards Commercial)? Yes, since you are still PIC. What you cannot do is be compensated for that flight. Pro-rate based fuel sharing is acceptable.&lt;/p&gt;&#xA;" OwnerUserId="12622" LastActivityDate="2015-12-10T21:50:02.053" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23577" PostTypeId="1" CreationDate="2015-12-10T22:50:49.790" Score="25" ViewCount="2018" Body="&lt;p&gt;There have been a couple of Airbus disasters where, in the confusion leading up to the crash, both pilots have attempted to control the aircraft with their sidesticks at the same time. In the absence of either pilot using the priority button, the effect of this is that both inputs are added, and the result clamped to the maximum single input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the face of it, this is a very curious design decision. Obvious alternatives include prioritising the left-seat stick (unless the priority button is used), or even averaging (instead of summing) the inputs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the original reasons for this design decision documented? Is there an advantage to summing the inputs?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2017-06-10T20:44:58.920" Title="Why do Airbus sidesticks add their inputs?" Tags="&lt;airbus&gt;&lt;sidestick&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23578" PostTypeId="1" AcceptedAnswerId="23581" CreationDate="2015-12-11T00:00:22.683" Score="8" ViewCount="2236" Body="&lt;p&gt;What are the FAA regulations on grass airstrips like grass height, lighting, necessary aircraft equipment, and the like? &lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="15311" LastEditDate="2019-05-30T21:01:32.753" LastActivityDate="2019-05-30T21:01:32.753" Title="What are the FAA regulations on grass airstrips?" Tags="&lt;faa-regulations&gt;&lt;runways&gt;&lt;grass-field&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23579" PostTypeId="1" AcceptedAnswerId="23600" CreationDate="2015-12-11T01:05:26.517" Score="3" ViewCount="116" Body="&lt;p&gt;I hear general claims that insurance companies dislike VFR-only pilots and that premiums fall as airmen move up in hours, ratings, and certificate levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the hard data from the actuarial tables? How do the profiles compare for owners versus renters?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2015-12-11T19:00:54.163" Title="What are typical insurance premium reductions for renters and owners as they earn instrument and commercial tickets?" Tags="&lt;insurance&gt;&lt;renters-insurance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23580" PostTypeId="1" AcceptedAnswerId="23585" CreationDate="2015-12-11T03:04:20.410" Score="7" ViewCount="3725" Body="&lt;p&gt;I was reading an article on deep vein thrombosis in air travel. It seems that the problem is more prevalent than one would think. A great deal of effort goes into preventing planes from crashing but people are many times more likely to die from pulmonary embolism than a plane crash. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering what steps have been taken to mitigate the health risks for pilots who spend many more hours sitting in a cramped seat at 8,000 ft of cabin altitude than most passengers. The most common advice for travelers is to do exercises to keep blood flowing and get up and move around occasionally. Is this practical for pilots? It doesn't seem like there is enough leg room to do exercises, not to mention that there are rudder pedals that could cause problems if you push them at the wrong time. If one of the pilots gets up the other pilot is often required to wear his oxygen mask until the first pilot returns. This would tend to make the pilots keep their cockpit excursions to an absolute minimum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do most pilots wear pressure stockings? That is another way to help prevent DVT. Is this a priority among the airlines and pilots themselves?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2017-01-30T22:36:39.020" Title="What do pilots do to prevent DVT?" Tags="&lt;crew&gt;&lt;seats&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23581" PostTypeId="2" ParentId="23578" CreationDate="2015-12-11T03:46:12.277" Score="11" Body="&lt;p&gt;I went poking around the FAA &lt;a href=&quot;http://rgl.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;Regulatory and Guidance Library&lt;/a&gt; until I found &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgFAR.nsf/0/C4BECA5E3994416C86256EBB005C3431?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 139.307&lt;/a&gt;, which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 139.307&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Unpaved areas.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) In a manner authorized by the Administrator, each certificate&#xA;  holder [must] maintain and promptly repair the surface of each gravel,&#xA;  turf, or other unpaved runway, taxiway, or loading ramp and parking&#xA;  area on the airport that is available for air carrier use as follows:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(b) FAA Advisory Circulars contain methods and procedures for the maintenance and configuration of unpaved areas that are acceptable to the Administrator.&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I went looking for those advisory circulars.  There are probably more that I haven't found, but &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5300-13A-chg1-interactive-201705.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 150/5300-13A - Airport Design&lt;/a&gt; beginning at page 82 seems to have the sort of thing you're looking for.&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="21864" LastEditDate="2017-07-03T17:03:20.560" LastActivityDate="2017-07-03T17:03:20.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23582" PostTypeId="2" ParentId="23571" CreationDate="2015-12-11T04:03:23.620" Score="4" Body="&lt;p&gt;Yes indeed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5Crgad.nsf/0/7F39338C0FC20B6586256E01005477BC?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;AD 69-24-04 PIPER&lt;/a&gt; increases the Vmc speed of the Twin Comanche by 9 knots because the aircraft was discovered to enter an unrecoverable flat spin when stalled near Vmc.  Always a bummer when that happens.&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-12-11T04:03:23.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23583" PostTypeId="2" ParentId="23571" CreationDate="2015-12-11T04:04:47.523" Score="7" Body="&lt;p&gt;I'm pretty sure this is not the kind of &quot;maneuver&quot; you're looking for, but it is&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;something stupid that I can do as a Pilot in a Single Engined Piston GA aircraft that I simply won't be able to recover from.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;CAPS deployment in an SR-20/22 is unrecoverable - once the chute is out, there's no putting it back in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VUsBV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VUsBV.jpg&quot; alt=&quot;SR-20 with parachute deployed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-12-11T04:04:47.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23584" PostTypeId="1" CreationDate="2015-12-11T04:41:04.113" Score="2" ViewCount="507" Body="&lt;p&gt;Trying to stay fresh on instrument regs, and I'm reviewing when you are able to bypass a procedure turn. I'm reading that if you perform a teardrop entry for a hold, you may. Does that mean you have to do the entire hold before proceeding the approach when you do a parallel entry? &#xA;&lt;a href=&quot;https://i.stack.imgur.com/t9mgr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t9mgr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12239" LastEditorUserId="19" LastEditDate="2016-07-28T16:27:13.280" LastActivityDate="2016-07-28T16:27:13.280" Title="When do I have to hold during an instrument procedure?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;approach&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23585" PostTypeId="2" ParentId="23580" CreationDate="2015-12-11T04:53:26.350" Score="4" Body="&lt;p&gt;Deep vein thrombosis (DVT) or Traveler’s Thrombosis occurs when blood in a vein (most often in lower extremities) becomes stagnant and then forms clot. If you think about it, the pilots are at less risk compared to passengers in this matter. &lt;a href=&quot;https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/DVT_07182005.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA advices&lt;/a&gt; certain steps to prevent DVT, like,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Increasing leg muscle activity during long periods of sitting improves blood flow in the legs. This may include walking around the cabin or exercising your lower legs and ankles while seated.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Drinking adequate fluids, and avoiding alcohol and caffeine, may also help by preventing dehydration.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some recommend taking short naps, instead of long ones, to avoid prolonged&#xA;inactivity.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It would be much easier for the pilots to do these things compared to say, passengers.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots usually have more room in the cockpit compared to passengers in cabin.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In long haul flights, there is usually a standby crew member who is rotated so that the pilot could get some movement and rest.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is certainly practical for the pilot to get up and stretch his/her legs during flight. It is not as if they are flying the aircraft hands-on every second for the entire flight. In any case, the flying duties could be alternated between the two flight crew without any problem.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is not unknown for pilots to take short naps in the cockpit&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Studies indicate that the DVT is more prevalent among the passengers than the pilots. According to &lt;a href=&quot;http://medind.nic.in/iab/t03/i2/iabt03i2p17.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Deep vein thrombosis in commercial pilot&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;10 percent of air travel passengers older than 50 years develop symptomless DVT during prolonged flights. DVT among air travellers has been documented, but is rare among pilots flying commercial aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also, it seems (some pilots, at least) &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/2081082/&quot; rel=&quot;nofollow noreferrer&quot;&gt;do wear&lt;/a&gt; flight socks.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;It seems that the pilots &lt;a href=&quot;http://www.ainonline.com/aviation-news/aviation-international-news/2010-01-26/study-pilots-ignore-oxygen-regulations&quot; rel=&quot;nofollow noreferrer&quot;&gt;don't take the wearing of oxygen mask seriously&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-11T04:53:26.350" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23586" PostTypeId="2" ParentId="23584" CreationDate="2015-12-11T05:14:10.530" Score="2" Body="&lt;p&gt;I suspect you are thinking of &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-4-8 (b)(2)&lt;/a&gt; [page 5-4-31], which states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;When a teardrop procedure turn is depicted and a course reversal is required, this type turn must be executed. &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If so, have a look at the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Flying Handbook, page 7-31&lt;/a&gt;.  &lt;strong&gt;The teardrop procedure turn is not referring to the same thing as a teardrop entry into a hold-in-lieu-of-procedure turn, it's something different entirely.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0klSV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0klSV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-12-11T05:14:10.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23587" PostTypeId="2" ParentId="23516" CreationDate="2015-12-11T06:06:28.377" Score="1" Body="&lt;p&gt;Cessna 140s can be fitted per STC rules with a Lycoming 0290D2 or 0290D or 0235 and do need extra weight in the aft section to get the CG right. Useful load goes down. The gross weight stays the same. Depending on many factors and perhaps operational safety one might get a gross weight increase approval for instance extra fuel if all other factors made it safe and reasonable. Most designs did not factor in larger than the engine used for the design and weight must have a certain &quot;cushion of safety&quot; like 150 percent above normal operating limits designed in. Certified VS Experimental and usage like holding out to the public for instance part 135 or part 121, racing planes etc. also effect allowable limits. Most basic a safety issue and thus a regulation effect concerning safety governs increases in gross weight.&lt;/p&gt;&#xA;" OwnerUserId="12624" LastActivityDate="2015-12-11T06:06:28.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23588" PostTypeId="1" CreationDate="2015-12-11T06:21:01.633" Score="0" ViewCount="962" Body="&lt;p&gt;i have seen on the webs about the additive manufacturing about this bracket here but I have no clues on where is it located and whats the purpose of it. Do give me any links if there are actually any if possible.&lt;/p&gt;&#xA;" OwnerUserId="12625" LastActivityDate="2015-12-11T06:55:14.857" Title="what is the use and the locations of nacelle hinge bracket?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23589" PostTypeId="2" ParentId="23588" CreationDate="2015-12-11T06:55:14.857" Score="1" Body="&lt;p&gt;I'm assuming that you're talking about the part below. The part was changed from cast steel to titanium DMLS additive manufacturing technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iztCu.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iztCu.png&quot; alt=&quot;Nacelle hinge&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from belement.co.il&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hinge is used to hold the engine nacelle cowling when opened. YOu can see four of them (older versions) on top of the open cowing in the image below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XfZ1F.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XfZ1F.jpg&quot; alt=&quot;open cowling&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from article.wn.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-11T06:55:14.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23590" PostTypeId="1" CreationDate="2015-12-11T08:59:40.190" Score="0" ViewCount="133" Body="&lt;p&gt;As per subject why is this done? Doesn't it make operations more confuseing as we have to references for every single passenger? A ticket number seems to be unique so why is this not used for all passenger references?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-12-11T09:30:02.720" Title="Why do we have a booking code and a ticket number?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-11T16:10:13.897" ContentLicense="CC BY-SA 3.0" />
  <row Id="23591" PostTypeId="2" ParentId="23590" CreationDate="2015-12-11T09:30:02.720" Score="1" Body="&lt;p&gt;Part of it is a hold-over to historical systems (where airlines ran their own booking systems). Now that most airlines use a global system like Amadeus this is less of an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ticket number (PNR) and booking number (record locator) do have slightly different purposes though. The former contains the details needed for the actual flight (your name, contacts details, flight numbers, etc) while the record locator can also contain other information not directly related to the flight.&#xA;In short: The record locator contains a reference to the PNR but can also contain additional information that is not contained in the PNR.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2015-12-11T09:30:02.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23593" PostTypeId="1" AcceptedAnswerId="23601" CreationDate="2015-12-11T11:49:47.237" Score="6" ViewCount="1402" Body="&lt;p&gt;I have this study question on the FIA written:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which statement is true concerning the aerodynamic conditions which occur during a spin entry?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Correct Answer: After a &lt;strong&gt;full stall&lt;/strong&gt;, the wing that drops continues in a stalled condition while the rising wing regains and continues to produce some lift, causing the rotation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incorrect Option: After a &lt;strong&gt;partial stall&lt;/strong&gt;, the wing that drops remains in a stalled condition while the rising wing regains and continues to produce lift, causing the rotation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because the only difference between the two answer options is 'full' and 'partial' I was wondering what are the differences between a full stall and a partial stall?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-12-11T19:30:49.443" Title="What is the difference between a partial stall and a full stall?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23594" PostTypeId="1" CreationDate="2015-12-11T12:33:01.000" Score="0" ViewCount="483" Body="&lt;p&gt;A question from the aerodynamics section of the FIA written:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which action will result in a stall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incorrect answer: Flying at too low an airspeed&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Correct answer: Exceeding the critical angle of attack&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could be flying in straight and level flight and if I slow down below stall speed the airplane will stall. So how can it be said that flying at too low an airspeed will not result in a stall?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="11402" LastEditDate="2015-12-11T12:41:18.997" LastActivityDate="2015-12-11T13:21:33.887" Title="How is a stalling speed not affected by airspeed?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-12-11T14:04:47.577" ContentLicense="CC BY-SA 3.0" />
  <row Id="23595" PostTypeId="2" ParentId="23594" CreationDate="2015-12-11T13:21:33.887" Score="1" Body="&lt;p&gt;Flying at too low an airspeed &lt;strong&gt;will&lt;/strong&gt; result in a stall, but what &quot;too low&quot; is entirely depends on the situation. For example, if you try a very steep climbing turn, you can stall at an airspeed where you would be fine in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is an incorrect answer, not because it's factually wrong, but just because it's not general enough. Exceeding the critical angle of attack always causes a stall, and it is the cause of every stall, so it's the best answer to the question. The examiner wants you to understand that the angle of attack is the mechanism that causes stalling, and that it can happen at different speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's quite common for these (and other multiple choice) exams to have an &quot;incorrect&quot; answer that isn't completely wrong, but isn't as good as the correct answer because it only applies in some conditions or is less general in some other way. In this case, another &quot;incorrect&quot; answer would be &quot;pulling the stick back too far&quot;. That's an action that might result in a stall, if you're already at a high angle of attack, but it's not really the cause and isn't always true.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-12-11T13:21:33.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23596" PostTypeId="1" CreationDate="2015-12-11T13:30:59.930" Score="8" ViewCount="779" Body="&lt;p&gt;When approaching Innsbruck (ICAO: LOWI) from the east, you intercept a localizer (111.10) which also provides glide slope indication. I believe this should be used just for guidance and not for A/P controlled descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Making the western approach, you intercept another localizer (109.70) that guides you in the right direction before making the final circling procedures towards the runway. However, this one has no glide slope guidance, and you have to manually compare the current altitude and DME values to the ones in the profile given in the charts (excerpt below) and correct the descent accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering why this is. The descent in the western approach is by no means easier than when coming from the east, see images below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approaches differ somewhat in that the eastern localizer gives guidance all the way to runway 26, albeit offset by 5 degrees, but the western localizer is placed far from the airport and is used to get to the start of the circling procedures to either runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could this be the reason that glide slope guidance is omitted, or are there other reasons not to provide this support in the western approach? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&#xA;I would like to expand and clarify this question to give it a more general touch. Are there regulations that control the appropriateness of g/s equipment when it comes to the particulars of the terrain or the vicinity to the runway? Are there other properties (geographical or other) that would limit its usability?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Eastern approach profile&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f1EUH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f1EUH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Western approach profile&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cmR6L.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cmR6L.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11665" LastEditorUserId="19" LastEditDate="2016-07-08T11:42:24.680" LastActivityDate="2016-07-08T11:42:24.680" Title="What is the reason for not providing glide slope guidance on the western approach to Innsbruck?" Tags="&lt;instrument-flight-rules&gt;&lt;localizer&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23597" PostTypeId="2" ParentId="23596" CreationDate="2015-12-11T15:59:19.517" Score="7" Body="&lt;p&gt;Looking at the charts, I can see quite a few good reasons for not providing glideslope for the West approach:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The East approach leads you (almost) directly to the runway threshold, the West approach leads you a few miles east of the airport.&lt;/li&gt;&#xA;&lt;li&gt;The East approach has more terrain clearance. If you go only slightly below the glideslope for the West approach, you will be dangerously close to terrain.&lt;/li&gt;&#xA;&lt;li&gt;The descent profile is steeper for the West approach: you are expected to lose 1500 feet for every 3 miles you travel. For the East approach it's 1320 feet for every 3 miles.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Number 1 is very important. If some pilot decides to blindly follow the ILS needle on a East approach, eventually he'll see the runway. If a pilot does the same on a West approach, eventually he'll crash his plane somewhere in the valley. The absence of glideslope reminds the pilot he has to pay attention to the vertical space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tracking the glideslope accurately is also pointless, as the pilot will transition to a visual approach and circle around anyway. It won't make big difference if you were a little bit off the initial descent.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For reference, East approach:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/IKhZ8.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IKhZ8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;West approach:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CtipK.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CtipK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-12-11T16:09:40.010" LastActivityDate="2015-12-11T16:09:40.010" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23598" PostTypeId="2" ParentId="23593" CreationDate="2015-12-11T16:49:33.160" Score="3" Body="&lt;p&gt;Sounds like a poorly worded question on the FAA's part.  I don't think there is a useful definition of &quot;partial&quot; stall.  Most FAA questions come from FAA references like the Pilot's Handbook of Aeronautical Knowledge, so you could check there.  Beware that that book and other FAA publications are full of errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vaguely related: If the airplane is rotating (rolling and yawing) but the airspeed is increasing rapidly, then that is a spiral dive, not a spin.&lt;/p&gt;&#xA;" OwnerUserId="3700" LastActivityDate="2015-12-11T16:49:33.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23600" PostTypeId="2" ParentId="23579" CreationDate="2015-12-11T19:00:54.163" Score="6" Body="&lt;p&gt;(This is a US-based answer.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no statistical information that I could find out there about this, but aircraft type, total hours, hours in type, age, previous claims etc. are all factored into the premium as well, so it's hard to make a simple comparison based on one variable. And as AOPA &lt;a href=&quot;https://insurance.aopa.org/support/faqs&quot; rel=&quot;noreferrer&quot;&gt;says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Not all carriers have the same guidelines for when they will offer a&#xA;  premium reduction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But having said all that, it looks like an instrument rating is the key qualification to get. AOPA's &lt;a href=&quot;https://insurance.aopa.org/support/faqs&quot; rel=&quot;noreferrer&quot;&gt;insurance FAQ&lt;/a&gt; recommends it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Typical actions you can take to reduce your rates include:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...] Obtain an instrument rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess you could go through AOPA's &lt;a href=&quot;http://insurance.aopa.org/aviation/owners-insurance&quot; rel=&quot;noreferrer&quot;&gt;quote process&lt;/a&gt; multiple times with different data to see what premiums come out, but just calling them is probably easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.avemco.com/&quot; rel=&quot;noreferrer&quot;&gt;Avemco&lt;/a&gt; is a well-known aviation insurer and they're more specific. The wording is bit awkward but &lt;a href=&quot;https://avemco.com/owned-aircraft-insurance/faq.aspx#twelve&quot; rel=&quot;noreferrer&quot;&gt;it looks like&lt;/a&gt; an instrument rating reduces your premium with them by 10%:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Q: Is there any type of additional training that would lower my premiums?&lt;/strong&gt;&lt;br&gt;&#xA;  A: [...] obtain an upgraded certificate or Instrument&#xA;  Rating and you become eligible for the full 10% savings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They don't say what an &quot;upgraded certificate&quot; means, but if you're one of the few people who have a commercial certificate but no instrument rating then perhaps that would count. Other insurance companies also say that advanced ratings can reduce your rates (&lt;a href=&quot;http://jetinsurance.com/faq/#reducerates&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, &lt;a href=&quot;http://www.regalaviation.com/frequently-asked-aviation-insurance-questions.php#What_can_I_do_to_lower_my_premium&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, I can add a couple of comments from personal experience. I have AOPA renter's insurance and it's flat rate: your certification and experience don't matter at all. Second, when I was looking for life insurance, having an instrument rating cut my premiums a lot but it was a while ago and I can't remember the exact numbers. I do remember that they were reluctant to even consider me without it.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-11T19:00:54.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23601" PostTypeId="2" ParentId="23593" CreationDate="2015-12-11T19:30:49.443" Score="5" Body="&lt;p&gt;For GA aircraft with straight, rectangular wings, the stall usually starts at the root and progresses towards the tip. So, at some point, only a portion of the wing will be stalled. This is sometimes referred to as partial stall, though it is not a common term.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7IXaF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7IXaF.jpg&quot; alt=&quot;Partial stall&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from boldmethod.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is usually achieved by having a washout or a wing cuff. In case of root-first stall, the wing tips are still producing lift, helping to prevent rolling motion (which may occur if the whole wings stalls at once), which in turn prevents the aircraft from entering a spin. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-11T19:30:49.443" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23602" PostTypeId="1" AcceptedAnswerId="23604" CreationDate="2015-12-12T00:31:28.783" Score="2" ViewCount="137" Body="&lt;p&gt;Obviously this website is great as is boldmethod and several of the aviation youtube channels. Also the FAA wings website is great as is all the FAA handbooks and advisory circulars. I also like to use the ASA study guides for the oral exams. Are there any other high quality sources of information that pilots should be taking advantage of, preferably free or low cost?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-12-12T01:25:46.983" Title="What free online educational resources should pilots in training be aware of?" Tags="&lt;general-aviation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23603" PostTypeId="1" AcceptedAnswerId="23605" CreationDate="2015-12-12T01:21:29.357" Score="9" ViewCount="4120" Body="&lt;p&gt;Let's assume  that I fly every weekend with a friend which is not a pilot. Can I log that time as PIC and count the takeoffs and landings toward the currency requirement as stated below: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.57&quot;&gt;Sec. 61.57&lt;/a&gt;: Except as provided in paragraph (e) of this section, no person may act&#xA;  as a pilot in command of an aircraft carrying passengers or of an&#xA;  aircraft certificated for more than one pilot flight crewmember unless&#xA;  that person has made at least three takeoffs and three landings within&#xA;  the preceding 90 days, and -- The person acted as the &lt;strong&gt;&lt;em&gt;sole manipulator&#xA;  of the flight controls;&lt;/em&gt;&lt;/strong&gt; and The required takeoffs and landings were&#xA;  performed in an aircraft of the same category, class, and type (if a&#xA;  type rating is required), and, if the aircraft to be flown is an&#xA;  airplane with a tailwheel, the takeoffs and landings must have been&#xA;  made to a full stop in an airplane with a tailwheel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does &lt;strong&gt;&lt;em&gt;sole manipulator of the flight controls&lt;/em&gt;&lt;/strong&gt; means solo and by yourself (alone) in the airplane such as Cessna-172 or does it mean you can have a non-pilot passengers?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastActivityDate="2015-12-14T14:04:05.547" Title="Should 3 takeoffs and landings to stay day current be solo?" Tags="&lt;faa-regulations&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23604" PostTypeId="2" ParentId="23602" CreationDate="2015-12-12T01:25:46.983" Score="3" Body="&lt;p&gt;The &lt;a href=&quot;http://www.aopa.org/&quot; rel=&quot;nofollow&quot;&gt;Airplane Owners And Pilots Association&lt;/a&gt; has lots of great articles on both training and new legislation that comes down the pike. The new information is really nice as it lets you know what may be or has changed since the last time you studied the books. Its worth it to join as well (its less than $50 a year and if you have just started to train they are about to bombard you with mailers anyway). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along with publishing the FAR's the FAA publishes lots of &lt;a href=&quot;https://www.faa.gov/news/safety_briefing/&quot; rel=&quot;nofollow&quot;&gt;Briefings&lt;/a&gt; and really great supplemental &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/&quot; rel=&quot;nofollow&quot;&gt;material and handbooks&lt;/a&gt; like this one &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot; rel=&quot;nofollow&quot;&gt;on airspaces&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lots of Youtube channels out there with great information like &lt;a href=&quot;https://www.youtube.com/user/FlightChops&quot; rel=&quot;nofollow&quot;&gt;FlightChops&lt;/a&gt; and the like, but note they are not in any way approved training and may not cover every aspect of what they are doing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to read &lt;a href=&quot;http://generalaviationnews.com/&quot; rel=&quot;nofollow&quot;&gt;GeneralAviationNews.com&lt;/a&gt;. Its a nice source of informative articles on what is happening around general aviation, airplane ownership advice, mechanical engine advice, and all all manners of legislation that are being discussed as well as fun fly ins and things like that. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-12-12T01:25:46.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23605" PostTypeId="2" ParentId="23603" CreationDate="2015-12-12T01:33:02.810" Score="14" Body="&lt;p&gt;Yes you can count that time as PIC and towards this currency requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulation requires that you are the only one who moved the flight controls during takeoff and landing. This means you could fly with anyone else in the cockpit (including a flight instructor, another pilot, or non-pilot friends) but you alone must be the person who performs those takeoffs and landings in order to remain qualified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This eliminates a few scenarios from counting towards the currency requirement, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You flew with another pilot, counted yourself as PIC (because you were more qualified or by prior arrangement) but didn’t actually do the work yourself&lt;/li&gt;&#xA;&lt;li&gt;You flew with an instructor, and they helped you with the landings&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-12-12T01:33:02.810" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23606" PostTypeId="1" AcceptedAnswerId="23607" CreationDate="2015-12-12T04:35:07.397" Score="1" ViewCount="1591" Body="&lt;p&gt;How do missiles successfully hit an air target despite the fact that nearly all Military aircraft are equipped with countermeasures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Heat Seeker/Infrared missiles : IR Flares as countermeasure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar guided missile : Chaff dispersal as countermeasure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Laser guided missile : Flood Laser to blind missile as countermeasure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which guidence system has most probability in hitting the target even when enemy deploys countermeasures, is there any guidence systems known which don't have a countermeasure?&lt;/p&gt;&#xA;" OwnerUserId="12634" LastEditorUserId="7532" LastEditDate="2015-12-12T17:08:47.903" LastActivityDate="2015-12-12T17:08:47.903" Title="Air to air Missile Guidance vs countermeasures" Tags="&lt;missiles&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2015-12-12T10:05:37.930" ContentLicense="CC BY-SA 3.0" />
  <row Id="23607" PostTypeId="2" ParentId="23606" CreationDate="2015-12-12T05:14:42.683" Score="1" Body="&lt;p&gt;Basically, the missiles are engaged in a (deadly) game with the aircraft every time a missile is fired. All countermeasures are based on 'confusing' the missile homing systems to a certain extent, usually in the terminal stage. Missiles (or AD systems in general), use a number of methods to overcome this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The general term for overcoming the countermeasures used by the aircraft is called counter-counter measure (CCM); in case of electronic warfare, electronic counter-counter measure (ECCM) is used. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of IR missiles, the aircraft should first know it is being targeted. The usual method is to use a Missile Approach Warning Sensor (MAWS), which detects the missile plume. However, this is not a foolproof method. As far as IR missiles are concerned, the target is usually unaware of the missile lock. The problem with laser guided short range missiles is also quite similar.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A number of newer missiles have dual/multi mode seekers (like IR/UV in Stinger), which helps it differentiate better between the target and decoy. Though decoys can mimic the target in one band (for e.g. IR), it cannot mimic in both the bands (flares have different UV signatures compared to the aircraft).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The missiles can be programmed to ignore the decoy (for e.g chaff) and lock only onto the target signature (rather than locking on to the strongest signal return).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The missiles can differentiate between the target and decoy using the differences in their trajectory.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The missile can discriminate between the target and decoy by using a higher resolution seeker.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is quite difficult to have a system that couldn't be fooled. Though a video/TV guided missile would come quite close, it is quite impractical in real world. Some laser guided missiles are touted as 'unjammable', but this claim is questionable. Best option is to have a multi-mode seeker that locks onto the target in different regions of the electromagnetic spectrum, though this would make the missile too expensive (again, countermeasures are possible).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-12T05:14:42.683" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23608" PostTypeId="1" AcceptedAnswerId="23618" CreationDate="2015-12-12T06:06:32.433" Score="5" ViewCount="259" Body="&lt;p&gt;I am holding a US private pilot certificate with instrument rating, and planning to fly a single-engine aircraft from US to Mexico. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding legal, visa, airspace/ATC knowledge requirements, flight plan filing, what do I need to prepare and how may I find the materials (in English). &lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="62" LastEditDate="2015-12-14T17:26:24.053" LastActivityDate="2015-12-14T17:26:24.053" Title="What preparations should I have to fly from the US to Mexico?" Tags="&lt;faa-regulations&gt;&lt;international&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23609" PostTypeId="1" AcceptedAnswerId="23967" CreationDate="2015-12-12T15:30:13.233" Score="4" ViewCount="464" Body="&lt;p&gt;&lt;a href=&quot;https://www.foreflight.com/products/foreflight-mobile/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ForeFlight Mobile&lt;/a&gt; users who file flight plans without being authenticated to CSC DUATS will effectively &lt;a href=&quot;http://blog.foreflight.com/2014/05/12/rogerback-notifications-from-atc/&quot; rel=&quot;nofollow noreferrer&quot;&gt;file through Lockheed Martin Flight Services&lt;/a&gt; (LMFS).&lt;/p&gt;&#xA;&lt;p&gt;Considering that the LMFS route does not require my personal  &lt;a href=&quot;https://www.1800wxbrief.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;1800wxbrief.com&lt;/a&gt; credentials (unlike filing through CSC DUATS), will additional services connected to my LMFS profile such as &lt;a href=&quot;http://www.lockheedmartin.com/us/news/press-releases/2012/october/isgs-afss-acas-1011.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Adverse Condition Alerting Service (ACAS)&lt;/a&gt;, EasyActivate™/EasyClose™, Close Reminders, ATC Notices, and Surveillance Enhanced Search and Rescue (SE-SAR) be accessible through my mobile phone?&lt;/p&gt;&#xA;&lt;p&gt;In other words, will Lockheed associate my ForeFlight flight plan with my LMFS profile in order to send me text messages with information about TFRs, links to open and close flight plans, and so on?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="30490" LastEditDate="2021-02-20T03:02:11.880" LastActivityDate="2021-02-20T03:02:11.880" Title="Will Lockheed Martin Flight Services send me ACAS, EasyActivate™, and other text messages if I file my flight plan through ForeFlight Mobile?" Tags="&lt;flight-planning&gt;&lt;avionics&gt;&lt;lockheed-martin&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23610" PostTypeId="1" AcceptedAnswerId="23613" CreationDate="2015-12-12T16:23:24.523" Score="13" ViewCount="1273" Body="&lt;p&gt;While playing some airline management simulation games, I found all these checks to be some real kind of mess. If suppose I have a fleet of about 10 A-320s then if one them goes for any check, then I would end up losing about 10% of my earnings. How do real world airlines make up for these absent aircraft? Like, consider an A380. It takes more than 2 weeks for a C Check to complete (&gt;1 month for a D-Check), and it certainly translates into a big financial loss. How do airlines operate such routes routes in the mean time? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="8482" LastEditDate="2015-12-12T17:07:49.667" LastActivityDate="2015-12-13T14:44:15.210" Title="How do airlines manage routes when respective aircraft undergo B,C or D checks?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23611" PostTypeId="2" ParentId="23460" CreationDate="2015-12-12T16:29:59.380" Score="1" Body="&lt;p&gt;If you go into a glider hangar, you'll find a bunch of club chutes, all of which have been repacked before the beginning of the season, and last 180 days. Sometimes the chute has a pocket for the log, other times it's under one of the flaps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I always wonder how much risk there would be  flying in a glider with a slightly outdated chute at the end of the season. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2015-12-12T16:29:59.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23612" PostTypeId="2" ParentId="23610" CreationDate="2015-12-12T16:48:42.420" Score="4" Body="&lt;p&gt;In general, airlines plan the checks required for aircraft into their schedule. For example, if you have 10 aircraft, you can schedule the routes for only 8 aircraft, assuming that the remaining are in some form of &lt;em&gt;scheduled&lt;/em&gt; checks. The bigger problem for airlines is when something unexpected happens, like there is a technical problem or an aircraft is unable to reach its source airport due to weather etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In such cases, the airliner can pull a  spare plane available (usually only in cases of large airlines) or 'roll' the next plane available (from a later time slot, usually in another route), hoping that the aircraft will become serviceable in the meantime. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-12T16:48:42.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23613" PostTypeId="2" ParentId="23610" CreationDate="2015-12-12T16:50:24.230" Score="17" Body="&lt;p&gt;Essentially they plan on some fraction of the fleet undergoing some sort of maintenance check at any one time, so they build their flying schedule around the remaining fraction.  And then there is some amount of flex due to things needing unscheduled maintenance or coming out of maintenance early.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes the task easier is the fact that maintenance needs can be forecast fairly far in advance, and so the schedules can be built around a knowledge of how many aircraft are likely to be available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an illustration (not necessarily representative of any particular airline's actual numbers), let's say you have a fleet of 200 aircraft, and you know that on average each aircraft will be down for two 2-week heavy maintenance checks each year.  That works out to essentially one month out of 12, each aircraft is down, or a little under 10% of the time.  Add in a little time for shorter maintenance visits (but still longer than an overnight), plus an allowance for the fact that some aircraft just need unscheduled work, and the maintenance planners may end up telling you to plan on 175 aircraft available each day.  So that's what you build your schedule around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's say that one aircraft takes a birdstrike &amp;amp; an engine needs to be changed.  That is now a hole in the schedule.  It can be covered by cancelling a flight (undesirable, but always an option).  If an aircraft is finished with maintenance ahead of schedule (say it was scheduled down all day for some work, but the work is actually done by noon), that aircraft may be able to be put into service.  Perhaps it's possible to delay some sort of minor maintenance a day (not a heavy check, but something quicker) and essentially create one aircraft-day of capacity, and push the check off to a weekend day when the schedule uses fewer aircraft.  Or maybe the schedule was built with one or two aircraft available as spares that day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on a variety of factors, spares may or may not be available, or even deliberately built into the schedule at all.  Having an A-380 sitting around unused all day is an EXPENSIVE insurance policy against something unforeseen happening, but cancelling a flight on something that big is an expensive event when it happens!  If you operate all out of one giant hub and you know that your fleet of 500 aircraft (flying 450 lines every day) is likely to have 2-4 aircraft every day go to the hanger for unexpected maintenance, it's probably a good financial decision to allocate two or three of those lines as dedicated spares.  If your aircraft operate a point-to-point schedule, it's harder (or unfeasible) to keep a spare aircraft at every airport you serve, &quot;just in case&quot; something happens to break there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are complicated decisions that airlines will continuously evaluate to find what balance works best for their particular operation.  In some cases, it may be possible to substitute an aircraft from a different fleet for a broken jet... an MD80 goes to the hanger, and a 737 with a reserve crew flies the rest of the day that the MD80 would have flown.  Or maybe a 757 broke, and the decision is to use the 737 to cover the flight, and re-accommodate the extra passengers that the 757 could hold that the 737 now can't.  That's a tactical decision that the airline's operations center will make, considering the availability of both aircraft and crews, as well as the passenger loads.  (They also may pull a &quot;healthy&quot; 757 off of its less full schedule to fly in place of the broke 757, use a 737 that wasn't going to be very full to cover that 757's route, put an RJ on the 737's route that day, and cancel the RJ's flights &quot;due to maintenance.&quot;  And if that inconveniences 4 flights of 40-50 people who mostly just get delayed a few hours, that's probably a better plan than stranding two flights of 200 people who'd otherwise have no way to get where they're going until tomorrow or later.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-12T16:55:59.823" LastActivityDate="2015-12-12T16:55:59.823" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23614" PostTypeId="2" ParentId="23610" CreationDate="2015-12-12T17:58:16.277" Score="2" Body="&lt;p&gt;As others have mentioned, you don't use all your airplanes.  You should plan to have some percentage of the fleet in heavy, scheduled maintenance and some other percentage of the feet as hot spares.  The purpose of the hot spares is to cover unscheduled maintenance as it happens and to avoid short delays when a simple 1-2 hour fix is needed.  The remainder of your fleet is what you use to build your schedule.  Yes, this isn't optimal since a fraction of your fleet is never generating revenue, but that is how it works. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-12T17:58:16.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23617" PostTypeId="2" ParentId="23428" CreationDate="2015-12-12T21:27:54.957" Score="2" Body="&lt;p&gt;i passed my medical exam and it was good, this issue wasn't a big problem at all even its not a problem.&lt;/p&gt;&#xA;" OwnerUserId="12552" LastActivityDate="2015-12-12T21:27:54.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23618" PostTypeId="2" ParentId="23608" CreationDate="2015-12-12T22:45:44.597" Score="5" Body="&lt;p&gt;AOPA has a guide &lt;a href=&quot;http://www.aopa.org/Flight-Planning/Mexico&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. I think it should cover most of your points apart from visa/immigration, because that isn't really an aviation issue (unless perhaps you're commercial air crew using a flight crew visa). Don't forget to plan ahead for re-entering the US, there are a bunch of requirements for that too, including using &lt;a href=&quot;https://eapis.cbp.dhs.gov&quot; rel=&quot;nofollow&quot;&gt;eAPIS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some points from the guide are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Documentation: you need a radio license for the pilot and the aircraft&lt;/li&gt;&#xA;&lt;li&gt;Insurance: add Mexico to your insurance policy if it isn't already covered&lt;/li&gt;&#xA;&lt;li&gt;Flight plan: you must be on an IFR or defense VFR flight plan to cross the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Defense_Identification_Zone&quot; rel=&quot;nofollow&quot;&gt;ADIZ&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Night VFR isn't allowed in Mexico (with a few exceptions for flights to the US)&lt;/li&gt;&#xA;&lt;li&gt;It looks like the more paperwork you have with you, the better&lt;/li&gt;&#xA;&lt;li&gt;FBO services are likely to be more limited than in the US, and fees are often higher&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also check out the &lt;a href=&quot;http://www.caribbeanskytours.com/&quot; rel=&quot;nofollow&quot;&gt;Caribbean Sky Tours Pilots Association&lt;/a&gt;, they publish a &lt;a href=&quot;http://www.caribbeanskytours.com/pilot_guide.html&quot; rel=&quot;nofollow&quot;&gt;pilots' guide&lt;/a&gt; to Mexico and Central America.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-12-14T17:25:38.087" LastActivityDate="2015-12-14T17:25:38.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23620" PostTypeId="1" AcceptedAnswerId="23623" CreationDate="2015-12-13T11:37:34.423" Score="8" ViewCount="1302" Body="&lt;p&gt;I acknowledge my very limited understanding of flight mechanics, but at first sight something tells me that the CG of the Suntoucher solar aircraft concept lies too far before the main wing and the forewing is too small to attain satisfactory stability and maneuverability.&lt;/p&gt;&#xA;&lt;p&gt;This geometry is not OK at all.&lt;/p&gt;&#xA;&lt;p&gt;Question:&#xA;&lt;strong&gt;Did I miss anything?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;The Suntoucher Solar Aircraft concept:&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tsWWs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tsWWs.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eyC5B.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eyC5B.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;References:&lt;/h3&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://wordlesstech.com/suntoucher-solar-powered-aircraft/&quot; rel=&quot;noreferrer&quot;&gt;wordlessTech&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.designboom.com/technology/suntoucher-solar-powered-aircraft-concept-by-samuel-nicz/&quot; rel=&quot;noreferrer&quot;&gt;designboom&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="247" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-06-08T13:11:29.067" Title="Is the Suntoucher CG too far aft?" Tags="&lt;aircraft-design&gt;&lt;stability&gt;&lt;canard&gt;&lt;maneuverability&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23621" PostTypeId="1" CreationDate="2015-12-13T12:22:13.337" Score="2" ViewCount="5459" Body="&lt;h1&gt;Thrust-Reverser-Systems&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;According to various sources, Thrust-Reverser-Systems can be classified as follows ( see e.g. &lt;a href=&quot;http://dx.doi.org/10.1007/978-3-642-34539-5&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bräunling's &quot;Flugzeugtriebwerke&quot;&lt;/a&gt;, &lt;a href=&quot;http://dx.doi.org/10.1007/978-3-540-79446-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rick's &quot;Gasturbinen und Flugantriebe&quot;&lt;/a&gt;, &lt;a href=&quot;https://engineering.purdue.edu/~propulsi/propulsion/jets/basics/reverse.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Purdue AAE Propulsion's &quot;Thrust Reversing&quot;&lt;/a&gt;, Aviation StackExchange Questions &lt;a href=&quot;https://aviation.stackexchange.com/questions/3754/how-does-thrust-reversal-work-on-a-jet-engine-and-when-should-it-be-used&quot;&gt;1&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/3777/what-is-the-difference-between-a-cold-stream-thrust-reverser-and-a-conventional&quot;&gt;2&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/7689/why-dont-planes-have-a-reverse-propeller-as-air-brakes&quot;&gt;3&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/14705/why-dont-most-fighters-have-thrust-reversers&quot;&gt;4&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/2007/why-cant-most-jets-safely-use-reverse-thrust-while-airborne&quot;&gt;5&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/14597/how-much-thrust-can-the-thrust-reversers-create&quot;&gt;6&lt;/a&gt; ):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Beta Range Propeller&lt;/strong&gt;&lt;br&gt;&#xA;Alternative names: Beta Mode Propeller, Beta Operation Propeller&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine Type(s): Piston-Prop or Turboprop with a Controllable-Pitch Propeller (CPP) / Variable-Pitch Propeller&lt;/li&gt;&#xA;&lt;li&gt;Mode of Operation: The pitch of the propeller blades is changed such that the propeller pushes air forward instead of backward.&lt;/li&gt;&#xA;&lt;li&gt;Specific Example: &lt;a href=&quot;http://www.airliners.net/photo/Norway---Air/Lockheed-Martin-C-130J-30/2171546/M/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Allison T56-A-15 on Lockheed C-130H Hercules&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Bucket Type Reverser&lt;/strong&gt;&lt;br&gt;&#xA;Alternative names: Bucket Door Reverser, Target (Type) System with External (Type) Doors, Clamshell Door Reverser, Post-Exit Thrust Reverser&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine Type(s): Turbojet or Low-Bypass Turbofan or Mixed-Flow High-Bypass Turbofan&lt;/li&gt;&#xA;&lt;li&gt;Controlling Mechanism: Hydraulic&lt;/li&gt;&#xA;&lt;li&gt;Mode of Operation: Bucket-shaped doors are closed after the engine nozzle. These deflector doors redirect the exhaust air to flow towards the front of the airplane.&lt;/li&gt;&#xA;&lt;li&gt;Specific Example: &lt;a href=&quot;https://www.flickr.com/photos/picturejohn64/4295098175/in/gallery-48018541@N04-72157623570087434/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce Tay 620-15 on a Fokker 70&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Clamshell Door Reverser&lt;/strong&gt;&lt;br&gt;&#xA;Alternative names: Deflector Door Reverser, Pre-Exit Thrust Reverser&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine Type(s): Turbojet or Low-Bypass Turbofan or Mixed-Flow High-Bypass Turbofan&lt;/li&gt;&#xA;&lt;li&gt;Controlling Mechanism: Pneumatic&lt;/li&gt;&#xA;&lt;li&gt;Mode of Operation: Similar to the Bucket Type Reverser. Distinction: The deflector doors are deployed before the engine nozzle (but after the last turbine stage).&lt;/li&gt;&#xA;&lt;li&gt;Specific Example: &lt;a href=&quot;http://www.airliners.net/photo/Japan-Coast-Guard/Gulfstream-Aerospace-G-V/0625322/M/&quot; rel=&quot;nofollow noreferrer&quot;&gt;BMW/Rolls-Royce BR710 on a Gulfstream Aerospace G-V Gulfstream V&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Cold Stream Reverser&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Cold Stream Cascade Reverser&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine Type(s): High-Bypass Turbofan&lt;/li&gt;&#xA;&lt;li&gt;Mode of Operation: The rear part of the nacelle (nacelle sleeve) slides back,&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;which activates the Cascades (guide vanes) to redirect the (outer/secondary) bypass air to flow towards the front of the airplane and&lt;/li&gt;&#xA;&lt;li&gt;which pivots Blocker Doors to block the (outer/secondary) bypass air just after the Cascades so that the air cannot follow its usual flow direction.&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;Specific Example: &lt;a href=&quot;https://www.flickr.com/photos/picturejohn64/4295096503/in/gallery-48018541@N04-72157623570087434/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rolls-Royce Trent 800 Series on a Boeing 777&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Cold Stream Pivoting Doors Reverser&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine Type(s): High-Bypass Turbofan&lt;/li&gt;&#xA;&lt;li&gt;Mode of Operation: The Pivoting Doors both to redirect the (outer/secondary) bypass air to flow towards the front of the airplane and block the usual flow path.&lt;/li&gt;&#xA;&lt;li&gt;Specific Example: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/b/b3/Airbus_A340-313E%2C_Finnair_JP7370785.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM International CFM56-5C2/4 on an Airbus A340&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Question&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Which Thrust-Reverser-Systems are used by which engines and aircraft?&lt;/strong&gt;&lt;br&gt;&#xA;So far, I just used standard search engines (web and image) and the &lt;a href=&quot;http://www.airliners.net/search/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net Photo Search&lt;/a&gt;, but here you have to trust the photographers that they correctly identified the aircraft and engine.&lt;br&gt;&#xA;Is there maybe an (official) list that provides the thrust-reverser-system for engine-aircraft-combinations?&lt;br&gt;&#xA;If no one has published data sheets with specific engines and the corresponding thrust-reverser-systems and of there is no databases which can be queried for the used thrust-reverser-system of a specific engine, I will accept such an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note: Feel free to extend the above information and/or turn it into a wiki.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-14T17:19:25.747" Title="Which Thrust-Reverser-Systems are used by which engines and aircraft?" Tags="&lt;thrust-reverser&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2015-12-13T21:37:25.913" ContentLicense="CC BY-SA 3.0" />
  <row Id="23622" PostTypeId="2" ParentId="23620" CreationDate="2015-12-13T12:24:06.670" Score="2" Body="&lt;p&gt;I think you are talking about the canards. Canard aircraft are much more common than you think and are certainly stable. For example, see this &lt;a href=&quot;https://en.wikipedia.org/wiki/Rutan_VariEze&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rutan VariEze&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X7Y2C.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X7Y2C.jpg&quot; alt=&quot;VariEze&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Static) stability means that the aircraft will return to its original position after a disturbance. For longitudinal stability (i.e. about the pitch axis), if some disturbance causes the aircraft angle of attack to increase, it should return t its original (lower) angle of attack by itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of the canard aircraft, the center of gravity is forward of the main wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Aoh4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Aoh4.jpg&quot; alt=&quot;Canard Stability&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from f-16.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, it is the main wing which is stabilizing. If for some reason, the angle of attack increases, the canard produces a moment about the c.g. that tends to increase the AoA. However, the wing also produces more lift (as AoA is higher), and this results in a stabilizing moment about the c.g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft may still (most probably) remain a dream for various reasons, though I doubt having a canard has anything to do with it (Actually, the span is on the larger side). Without details, its just speculation. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the aircraft looks similar to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rutan_Voyager&quot; rel=&quot;nofollow noreferrer&quot;&gt;Rutan Voyager&lt;/a&gt;, which holds the world endurance record and had &lt;a href=&quot;http://airportjournals.com/voyager-a-crazy-dream-part-ii/&quot; rel=&quot;nofollow noreferrer&quot;&gt;problems with pitch stability&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RMyL0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RMyL0.jpg&quot; alt=&quot;Voyager&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from nasa.gov&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-13T12:24:06.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23623" PostTypeId="2" ParentId="23620" CreationDate="2015-12-13T12:30:12.907" Score="7" Body="&lt;p&gt;Good catch! You are right, the center of gravity will be too much forward for a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21000/what-is-a-canard&quot;&gt;canard&lt;/a&gt;. If they put the prop on the sting behind the wing and the cockpit a bit ahead of the wing, things would look more credible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The size of the foreplane is not obviously wrong, but the booms at the tips of the foreplane look strange. They serve no obvious purpose, like the sting, and the tailbooms look too thin for transmitting the loads from the vertical surfaces into the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One third thing that looks odd are the control surfaces: The ailerons look too small to allow maneuvering in gusty weather at low speed. I guess the flaps on the inboard wing are for pitch control. Why are they not on the canard, where they would be more effective? Maybe because the center of gravity is so close to the foreplane, the designer decided to put them on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I agree with your assessment: This thing will remain an artist concept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison, see below a picture of a solar aircraft that actually flies and got most things right: The &lt;a href=&quot;http://www.icare-solar.de/index.php/flugzeug/?lang=en&quot; rel=&quot;nofollow noreferrer&quot;&gt;Icaré II&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p8u7t.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p8u7t.jpg&quot; alt=&quot;Icaré II in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Icaré II in flight (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/0/0a/Icare_1g.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-12-13T12:49:42.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23624" PostTypeId="1" AcceptedAnswerId="23627" CreationDate="2015-12-13T14:04:39.123" Score="-2" ViewCount="442" Body="&lt;p&gt;How and why are the accessories of modern fighter jet engines oriented with respect to the airplane? Do the subsystems show up (see left image part) or down (see right image part)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ojvUG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ojvUG.png&quot; alt=&quot;Jet engine accessories orientation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12646" LastEditorDisplayName="user12485" LastEditDate="2015-12-13T18:36:16.527" LastActivityDate="2015-12-13T18:36:16.527" Title="How are the accessories of fighter jet engines oriented (Turbojet or Low-Bypass-Turbofan)?" Tags="&lt;jet-engine&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23625" PostTypeId="2" ParentId="23610" CreationDate="2015-12-13T14:44:15.210" Score="2" Body="&lt;p&gt;Same way you manage &lt;em&gt;anything&lt;/em&gt;: with contingencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When your car insurance is up for renewal each year, do you suddenly go &quot;oh crap I don't have enough money for this&quot;, or do you save it up &lt;em&gt;over the year&lt;/em&gt; because you know it's coming?&lt;/p&gt;&#xA;" OwnerUserId="1931" LastActivityDate="2015-12-13T14:44:15.210" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23626" PostTypeId="1" AcceptedAnswerId="23631" CreationDate="2015-12-13T17:04:45.843" Score="7" ViewCount="1648" Body="&lt;p&gt;As a followup to &lt;a href=&quot;https://aviation.stackexchange.com/questions/22316/why-do-turbofan-blade-tips-exceed-the-speed-of-sound-while-prop-tips-should-not&quot;&gt;Why do turbofan blade tips exceed the speed of sounds while prop tips should not&lt;/a&gt; my question is: why have rings on propellers not been used to overcome this problem?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems from &lt;a href=&quot;http://www.propellersafety.com/ringprop/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt; site that they are produced at least for maritime use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://blog.modernmechanix.com/propeller-ring-raises-planes-speed/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; and &lt;a href=&quot;http://www.flightsim.com/vbfs/showthread.php?263872-Propeller-Ring-Raises-Plane-s-Speed-(Apr-1933)&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; it seems to have advantages and experiments have already been done as I can see from the picture. (I do not know how reliable it could be though)&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-13T18:43:02.707" Title="Rings around propellers" Tags="&lt;propeller&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2015-12-13T18:58:37.407" ContentLicense="CC BY-SA 3.0" />
  <row Id="23627" PostTypeId="2" ParentId="23624" CreationDate="2015-12-13T17:12:31.277" Score="4" Body="&lt;h1&gt;Engine Accessories On the Bottom&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The engine looks like the &lt;a href=&quot;http://www.geaviation.com/military/engines/f414/&quot; rel=&quot;nofollow noreferrer&quot;&gt;General Electric GE F414&lt;/a&gt;, which is used (amongst others) in the &lt;a href=&quot;http://www.boeing.com/defense/fa-18-super-hornet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing F/A-18E/F Super Hornet&lt;/a&gt; and the &lt;a href=&quot;http://saab.com/air/gripen-fighter-system/gripen/gripen/Proud-to-be-brazilian/the-fighter/the-gripen-ng-programme/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab Gripen NG&lt;/a&gt;. &lt;em&gt;In this case&lt;/em&gt;, the engine is mounted with the accessories below, i.e. in 6'O clock position. See this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SHGDN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SHGDN.jpg&quot; alt=&quot;Super Hornet Engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An Aviation Machinist’s Mate (AD) performs maintenance on an F/A-18F Super Hornet. ADs are aircraft engine mechanics. They inspect, adjust, test, repair and overhaul aircraft engines and propellers. Image from americasnavy.tumblr.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not correct that the engine accessories 'protrude below' the aircraft. The fusealge design is such that there are no protrusions, as can be seen in this image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PmzpY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PmzpY.jpg&quot; alt=&quot;Engine Closeup&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:US_Navy_040708-N-9060G-009_Aviation_Machinist%27s_Mate_3rd_Class_Evonda_Patterson,_of_Chicago,_Ill.,_performs_scheduled_maintenance_on_the_engine_of_an_F-A-18E_Super_Hornet.jpg#/media/File:US_Navy_040708-N-9060G-009_Aviation_Machinist%27s_Mate_3rd_Class_Evonda_Patterson,_of_Chicago,_Ill.,_performs_scheduled_maintenance_on_the_engine_of_an_F-A-18E_Super_Hornet.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;US Navy 040708-N-9060G-009 Aviation Machinist's Mate 3rd Class Evonda Patterson, of Chicago, Ill., performs scheduled maintenance on the engine of an F-A-18E Super Hornet&lt;/a&gt;&quot; by U.S. Navy photo by Photographer's Mate 3rd Class Michael Geary &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently, the reason for mounting the accessories down is for ease of maintenance as they can be accessed easily this way.&lt;br&gt;&#xA;Other engines with the accessories on the bottom are e.g. the &lt;a href=&quot;http://www.pw.utc.com/F119_Engine&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney F119&lt;/a&gt; for the &lt;a href=&quot;http://www.lockheedmartin.com/us/products/f22.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin F-22 Raptor&lt;/a&gt;, the &lt;a href=&quot;http://www.eurojet.de/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurojet EJ200&lt;/a&gt; for the &lt;a href=&quot;https://www.eurofighter.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter Typhoon&lt;/a&gt; and the &lt;a href=&quot;http://www.snecma.com/military-engines/training-and-combat-aircraft/m88&quot; rel=&quot;nofollow noreferrer&quot;&gt;SNECMA M88&lt;/a&gt; for the &lt;a href=&quot;http://www.dassault-aviation.com/en/defense/rafale/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassault Rafale&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Engine Accessories On Top&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;However, this varies from aircraft to aircraft, as evidenced by this &lt;a href=&quot;http://www.sukhoi.org/eng/planes/military/su30mk/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sukhoi Su-30MK&lt;/a&gt; with &lt;a href=&quot;http://www.uk-odk.ru/eng/products/military_aviation/al31f/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saturn AL-31F(P)&lt;/a&gt; engines with the accessories on top.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Rw9Sx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rw9Sx.jpg&quot; alt=&quot;Su 30 engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from researchingaliensandufos.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorDisplayName="user12485" LastEditDate="2015-12-13T18:23:47.847" LastActivityDate="2015-12-13T18:23:47.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23628" PostTypeId="1" AcceptedAnswerId="23647" CreationDate="2015-12-13T17:25:05.717" Score="37" ViewCount="31802" Body="&lt;p&gt;The F15-E Strike Eagle features a two-man cockpit. The pilot in the front seat and the WSO (Weapons System Officer) in the back seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the jet is cruising straight and level is mechanically sound but the pilot becomes completely incapacitated (from a heart attack for example) can the WSO take over and land the aircraft? I could imagine that the correct procedure may be to just eject both the pilot and themselves. &lt;strong&gt;Do WSO's learn to fly the F15?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image is the backseat cockpit area of a F-15 E where the WSO sits. Note the control stick and the throttle control I've highlighted with red arrows. Surely this means the WSO has the ability to take over control?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QCO93.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QCO93.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;source(&lt;a href=&quot;http://i61.tinypic.com/dbqp2q.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://i61.tinypic.com/dbqp2q.jpg&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="2097" LastEditorUserId="22550" LastEditDate="2018-12-14T23:01:42.577" LastActivityDate="2018-12-14T23:01:42.577" Title="On the F15-E, can the WSO take over if the pilot is incapacitated?" Tags="&lt;military&gt;&lt;jet&gt;&lt;us-air-force&gt;&lt;pilot-incapacitation&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23629" PostTypeId="2" ParentId="23628" CreationDate="2015-12-13T17:32:55.393" Score="27" Body="&lt;p&gt;Yes. They &lt;a href=&quot;http://www.f-15e.info/joomla/technology/cockpit/83-wso-flight-stick&quot;&gt;can fly the aircraft&lt;/a&gt; if required. The &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/f-15-variants.htm&quot;&gt;F-15E is developed from F-15D&lt;/a&gt; , which is used for aircrew training, with the instructing pilot in the rear seat.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There is atleast one documented case where the WSO controlled the aircraft, albeit briefly. On March 2012, a F-15E crashed, killing the pilot. During the accident, as a result of pilot actions, the WSO decided that the pilot has suffered spatial disorientation and attempted to recover, before initiating the ejection sequence. From &lt;a href=&quot;http://timemilitary.files.wordpress.com/2012/08/acc_f-15e_aib_082212.pdf&quot;&gt;USAF Accident Investigation Report&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At that point, the MWSO believed that the MP did not know which way was up ... . The MWSO grabbed the controls and rolled the MA left towards a near wings-level position... The MWSO then pulled 11 g while rolling left to wings-level... As the MWSO rolled the MA to nearly level flight, he initiated ejection for the MC...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-14T14:17:08.303" LastActivityDate="2015-12-14T14:17:08.303" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23630" PostTypeId="1" CreationDate="2015-12-13T18:20:35.113" Score="1" ViewCount="74" Body="&lt;p&gt;Compare&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wolframalpha.com/input/?i=Alaska+Airlines+764+yesterday+duration&quot; rel=&quot;nofollow&quot;&gt;http://www.wolframalpha.com/input/?i=Alaska+Airlines+764+yesterday+duration&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.wolframalpha.com/input/?i=Alaska+Airlines+771+yesterday+duration&quot; rel=&quot;nofollow&quot;&gt;http://www.wolframalpha.com/input/?i=Alaska+Airlines+771+yesterday+duration&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why the east-bound flight is about 20% faster than the west-bound reverse flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it because of the average airflow is east-bound?&lt;/p&gt;&#xA;" OwnerUserId="12647" LastActivityDate="2015-12-13T18:20:35.113" Title="Why east-bound flight is faster than the reverse flight along the same route?" Tags="&lt;flight-planning&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2015-12-13T19:05:10.680" ContentLicense="CC BY-SA 3.0" />
  <row Id="23631" PostTypeId="2" ParentId="23626" CreationDate="2015-12-13T18:43:02.707" Score="4" Body="&lt;p&gt;Propeller rings (ducted propeller) have been used un aircraft, notably in some early VTOL designs, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_X-22&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bell X-22&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Mississippi_State_University_XV-11_Marvel&quot; rel=&quot;nofollow noreferrer&quot;&gt;XV-11 Marvel&lt;/a&gt; and also the &lt;a href=&quot;https://en.wikipedia.org/wiki/RFB_Fantrainer&quot; rel=&quot;nofollow noreferrer&quot;&gt;RFB Fantrainer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LuyDQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LuyDQ.jpg&quot; alt=&quot;X-22&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bell X-22. Image from diseno-art.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They do have some advantages like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Better noise reduction and safety compared to 'open' propeller.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For the same thrust, the propeller can be made smaller.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The duct can be designed such that it provides a limited amount of thrust vectoring, useful if we are using it for STOL.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, they are not widely used because of various other reasons like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For effecient operation, the tip clearance should be very small. Any increase in tip clearance leads to rapid degradation in effeciency.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The duct and its support structures increase the weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The duct increases the drag at cruise speeds (as drag increases as square of velocity).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If we decide to use a lower sized propeller as a result of using the duct, the effeciency suffers- as we are actually accelerating a lower mass of air more (rather than accelerating a higher mass of air less, which is more effecient).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The design of the duct is difficult- the aiflow into the duct comes not only from the front, but is also sucked from the sides from the sides (i.e. the capture area is greater than the duct frontal area). If not designed properly, the flow may seperate, leading to loss of effeciency. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, ducted fans are used in a number of small UAVs (in &lt;a href=&quot;http://www.horizonhobby.com/category/airplanes/airplanes-14501--1/jets-ducted-fan&quot; rel=&quot;nofollow noreferrer&quot;&gt;RC model jet aircraft&lt;/a&gt;, for example, in lieu of miniature jets), electric aircraft like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_E-Fan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus E-fan&lt;/a&gt; and also some dirigibles.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In case you are asking about connecting the propeller tips like in the maritime propller in the link, the resulting stresses at high speed would tear the whole assembly apart, causing more problems than it solves. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-13T18:43:02.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23632" PostTypeId="1" AcceptedAnswerId="23644" CreationDate="2015-12-13T18:52:03.513" Score="9" ViewCount="165" Body="&lt;p&gt;Is there any way of knowing - for example by referring to an existing data repository or something similar - what commercial routes were operated from a given airport in a given year?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be a list of all commercial routes that have been discontinued.&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="1696" LastEditDate="2016-06-14T16:41:22.897" LastActivityDate="2016-06-14T16:41:22.897" Title="Is there any data repository of discontinued commercial routes?" Tags="&lt;commercial-aviation&gt;&lt;datasets&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23633" PostTypeId="2" ParentId="23577" CreationDate="2015-12-13T21:41:08.513" Score="14" Body="&lt;p&gt;I believe that there is some logic in the design, actually, even if I don't really fancy it. If you think of the traditional yoke as a control element where a certain force (or moment, rather...) results in a certain change of flight path, then if both pilots apply the same force (rather than targeting the same deflection), the resulting aircraft reaction is more pronounced than if only one pilot applies that force, although probably not with linear relation. The sidestick controlled flight control system does the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is missing much more, to my mind, is feedback to one pilot about what the other one is doing with the stick. I believe that having them interconnected or back driven would probably not have been such a bad idea.&lt;/p&gt;&#xA;" OwnerUserId="10025" LastActivityDate="2015-12-13T21:41:08.513" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23634" PostTypeId="2" ParentId="23297" CreationDate="2015-12-13T21:59:29.620" Score="0" Body="&lt;p&gt;gcmap.com allows drawing of range rings around airports. I think it's more geared up around longer range travel rather than the $100 burger, though.&lt;/p&gt;&#xA;" OwnerUserId="10025" LastActivityDate="2015-12-13T21:59:29.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23635" PostTypeId="2" ParentId="23420" CreationDate="2015-12-13T22:03:41.027" Score="6" Body="&lt;p&gt;&lt;strong&gt;Bird Strikes Worldwide&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to currently available data, &lt;strong&gt;it is estimated that a bird-strike event occurs once every 2000 flights&lt;/strong&gt; (Khan, Kapania &amp;amp; Johnson, 2010). Further analyses of bird-strike statistics have shown that only 20% of bird strikes are actually reported by aviation staff. This means that the extent of economic and human losses resulting from bird strike could be much higher than what is currently presumed (Chuan, 2006). Consequently, this suggests that conducting further indepth studies on how to better capture reliable bird-strike event statistics and formulating strategies and solutions&#xA;  would be beneficial.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/Final%20report%20Bird%20Strike%20Study.pdf&quot; rel=&quot;noreferrer&quot;&gt;EASA, &lt;em&gt;Bird Strike Damage &amp;amp; Windshield Bird Strike - Final Report&lt;/em&gt;, 2009&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It had been intended to use the International Civil Aviation Organization (ICAO) database of bird strike statistics as a prime source of bird strike information, giving details of worldwide bird strike incidents and accidents. However, despite the best endeavours of fera, Atkins and EASA, it was not possible to gain access to this source of information. Therefore the literature search does not include data from regions such as Asia and Australia. Reporting levels from these regions are low and it is likely that even with access to ICAO data, there would be limited useful information available beyond that already available from UK and USA/Canada sources. &lt;strong&gt;It is estimated, based on previous fera Bird Management Unit experience, that the UK and USA/Canadian data obtained represents approximately 50% of all worldwide bird strike reports.&lt;/strong&gt; Also regions such as Russia, China and South&#xA;  America do not routinely contribute data to the ICAO database.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wildlife Strikes in the United States of America&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/wildlife/media/Wildlife-Strike-Report-1990-2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA, &lt;em&gt;Wildlife Strikes to Civil Aircraft in the United States 1990-2014&lt;/em&gt;, 2015&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The number of strikes annually reported to the FAA has increased 7.4-fold from 1,851 in 1990 to a record 13,668 in 2014&lt;/strong&gt;. The 2014 total was an increase of 2,267 strikes (20 percent) compared to the 11,401 strikes reported in 2013. For 1990–2014, 156,114 strikes were reported. &lt;strong&gt;Birds were involved in 96.9 percent of the reported strikes, terrestrial mammals in 2.2 percent, bats in 0.8 percent and reptiles in 0.1 percent.&lt;/strong&gt; Although the number of reported strikes has dramatically increased, the number of reported damaging strikes has actually declined since 2000. Whereas the number of reported strikes increased 127 percent from 6,009 in 2000 to 13,668 in 2014, the number of damaging strikes declined 24 percent from 764 to 581. While there was a 20 percent increase in reported strikes from 2013 to 2014, the number of damaging strikes declined 4 percent from 606 to 581. The decline in damaging strikes has been most pronounced for commercial aircraft in the airport environment (at &amp;lt;1,500 feet above ground level [AGL]). Damaging strikes have not declined for general aviation (GA) aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:&lt;br&gt;&#xA;According to the FAA, there were approximately 11'500 bird strikes in the US in the year 2014.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in Australia&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;A significant proportion of all occurrences [...] involve aircraft striking wildlife, especially birds&lt;/strong&gt; (Bureau, 2009). According to a report (Australian aviation wildlife strike statistics: 2004-2013) providing aviation bird strike and animal strike occurrence data, &lt;strong&gt;reported bird strikes have increased from 1085 in 2004 to 1751 in 2011&lt;/strong&gt;. The Australian aviation industry experienced a reduction in reported bird strikes in 2012 relative to 2011.&lt;br&gt;&#xA;  Among the &lt;strong&gt;1568 reported bird strikes [...] in the year 2013&lt;/strong&gt;, [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in Brazil&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Brazil is one of the most suffered countries from bird strike because it has the world’s second largest aircraft fleet as well as the world’s second largest number of bird species. [...]&lt;br&gt;&#xA;  The annual number of reported bird strikes has increased from 235 in 1993 to 587 in 2004.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in the Czech Republic&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the period 1993–1999, the data relating to 165 collisions was entered into the Czech Air Force’s database.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in France&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The annual number of recorded bird-strike events in France exceeds 700, [...] (2008) [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in Iran&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Within the years 1996–2011, 271 bird collisions in 32 airports were registered by Iran’s Civil Aviation Organization (CAO).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in Saudi Arabia&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.icao.int/MID/Documents/2014/Wildlife%20and%20FOD%20Workshop/Risk%20Reduction%20program%20-%20GACA.pdf&quot; rel=&quot;noreferrer&quot;&gt;Kutbi, N., &lt;em&gt;Bird Strike&lt;/em&gt;, 2014&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;30 in 2011, 19 in 2012, 37 in 2013&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bird Strikes in the United Kingdom&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://dx.doi.org/10.1016/B978-0-08-100093-9.09993-3&quot; rel=&quot;noreferrer&quot;&gt;Hedayati, R., Sadighi, M., &lt;em&gt;Bird Strike&lt;/em&gt;, 2016&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The total number of reported strikes in the UK has increased from 608 in 1991 to 2365 in 2011: [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user12485" LastEditorDisplayName="user12485" LastEditDate="2015-12-13T22:08:59.507" LastActivityDate="2015-12-13T22:08:59.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23636" PostTypeId="1" AcceptedAnswerId="23637" CreationDate="2015-12-13T05:03:06.280" Score="2" ViewCount="781" Body="&lt;p&gt;Is there a regulation or rule about using handheld aviation transceivers e.g. Icom A-24 for ground to ground communication on MURS frequencies? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I just use Icom A-24 for ground to ground? or do I need FCC licence?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I use my handheld aviation transceivers (Icom A-24) for ground to ground communication? or do I need a FCC license? &lt;/p&gt;&#xA;" OwnerUserId="3455" OwnerDisplayName="PMoubed" LastEditorUserId="3455" LastEditDate="2015-12-14T23:40:43.507" LastActivityDate="2015-12-14T23:40:43.507" Title="Can I use my aviation handheld transceiver on MURS?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;radio&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23637" PostTypeId="2" ParentId="23636" CreationDate="2015-12-13T16:03:26.193" Score="4" Body="&lt;p&gt;You asked for legal opinion, so the main &quot;legal&quot; reason would be that a radio must be type-accepted for the service for which you want to use it. So unless Icom A-24 is MURS type accepted, and it is not, then it's illegal to use it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You don't need a special FCC license. FCC says this about licensing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;MURS is licensed by rule. This means an individual license is not&#xA;  required for an entity to operate a MURS transmitter if it is not a&#xA;  representative of a foreign government and if it uses the transmitter&#xA;  only in accordance with Section 95.1309. There is no age restriction&#xA;  regarding who may operate an MURS transmitter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the transmitter itself must be marked as MURS transmitter. FCC has this to say about that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A MURS transmitter must be certified by the FCC. A certified MURS&#xA;  transmitter has an identifying label placed on it by the manufacturer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is technical reason as well which makes it impossible to use it on higher VHF frequencies: Above 137 MHz, the traditional modulation type is FM. Aviation VHF is AM. So even if you wanted to talk to MURS users, you wouldn't be able to do so normally due to different modulation types used. Another technical issue is frequency coverage. A-24 can transmit 118.000 MHz to 136.975 MHz. I don't know if it's possible to unlock it for extra coverage (but I'd be surprised is that was possible, due to use case), but with default frequency coverage you can't go high enough to reach MURS frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE&lt;/strong&gt;:  I just checked and it seems that AM is actually allowed on MURS. So it is, and you can somehow unlock the A-24 to operate on those frequencies, you could technically speak to other AM MURS users, but again it wouldn't be legal due to licensing system used for MURS.&lt;/p&gt;&#xA;" OwnerUserId="2998" OwnerDisplayName="AndrejaKo" LastActivityDate="2015-12-13T16:15:29.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23638" PostTypeId="2" ParentId="23297" CreationDate="2015-12-14T01:37:14.000" Score="4" Body="&lt;p&gt;At least a couple of tools exist to search for airports beyond a certain distance from your departure point. You didn’t specify, so I will use mine: &lt;a href=&quot;https://skyvector.com/airport/HUA/Redstone-AAF-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;KHUA&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using &lt;a href=&quot;http://www.gcmap.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;gcmap.com&lt;/a&gt;, search for &lt;code&gt;near:KHUA beyond:50nm within:70nm&lt;/code&gt; to get a &lt;a href=&quot;http://www.gcmap.com/search?Q=near:KHUA+beyond:50nm+within:70nm&amp;amp;EL=near:HUA+beyond:50nm+within:70nm&amp;amp;ET=Fix+location&amp;amp;EC=D&amp;amp;P=near:HUA&quot; rel=&quot;nofollow noreferrer&quot;&gt;list of airports in the specified range&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To plot some of them on a map, place a few of those in a comma-separated list, e.g., &lt;code&gt;KHUA,KGAD,KBHM,KSYI,KBNA,KAYX,M22,TN50,KJFX,KMRC,KAPT,KPYP,1M4,M22&lt;/code&gt;, and select the Map tool. Plot range rings with one or more lines in the &lt;strong&gt;Ranges&lt;/strong&gt; box under &lt;strong&gt;Map Controls&lt;/strong&gt;. I used&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;50nm@KHUA&lt;br&gt;&#xA;  70nm@KHUA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Click the Draw Map button to update your map.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.gcmap.com/mapui?P=KHUA%2CKGAD%2CKBHM%2CKSYI%2CKBNA%2CKAYX%2CM22%2CTN50%2CKJFX%2CKMRC%2CKAPT%2CKPYP%2C1M4%2CM22&amp;amp;R=50nm%40KHUA%0D%0A70nm%40KHUA&amp;amp;PM=b%3Adisc7%2B%25i&amp;amp;MS=wls&amp;amp;DU=mi&quot; rel=&quot;nofollow noreferrer&quot;&gt;final result&lt;/a&gt; will resemble the image below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zVBND.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zVBND.png&quot; alt=&quot;50 to 70nm from KHUA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2015-12-14T01:37:14.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23639" PostTypeId="2" ParentId="23628" CreationDate="2015-12-14T03:03:55.853" Score="19" Body="&lt;p&gt;The WSO can do everything from the back seat, but there is one thing he cannot do. He can lower the landing gear, but he cannot raise it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as ejecting, the WSO has the option of ejecting himself or both.&lt;/p&gt;&#xA;" OwnerUserId="12652" LastEditorUserId="12140" LastEditDate="2015-12-14T08:59:19.223" LastActivityDate="2015-12-14T08:59:19.223" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23640" PostTypeId="2" ParentId="23565" CreationDate="2015-12-14T07:09:58.983" Score="11" Body="&lt;p&gt;As nobody has answered this in 4 days I'll add this &quot;layman's&quot; input.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not a pilot or aeronautically trained, but I understand that essentially all airliners have a dynamic yaw instability aka Dutch Roll and have stabilisers designed to address this. ANY feedback error correction system requires SOME error signal to derive the feedback from and how much error and how it manifests changes with system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;@mins I'm no expert in this area BUT all aircraft are different and you'd be surprised (or should be) if they all behaved the same. The overall combination of a wide range of dynamic forces leads to the end result. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I recall (probably from &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0750944854&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;Peter R March's very interesting 'The 747 story'&lt;/strong&gt;&lt;/a&gt;  Dutch roll was not a major factor in large aircraft until the larger jets and they lost a prototype with an experienced pilot inexplicably. Subsequent investigations and close calls showed the cause was a dynamic yaw-roll coupling. AFAIR this is caused by the high yaw-induced rolling moment of swept wings and as these are standard fare as speeds rise all large/fast modern airliners have this issue and have a yaw damper to make it unnecessary for the pilot to deal with it.&lt;br&gt;&#xA;Without a yaw damper, the vertical tail would need to be much larger to provide enough damping. This costs weight and drag and creates problems of its own due to the location of the tail upwards of the line of symmetry. When the aircraft yaws, the wing creates a rolling moment. This rolling motion causes a drag difference which, together with the directional stability of the tail, swings the aircraft's tail around to the other side, and the process repeats in the opposite direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be, and I'm 'mentating' this with no proof at all, that they are up against a regulatory barrier and that correcting the problem may lead to them having to do something else expensive. eg early British cars were long stroke not for any technical reason but due to taxation advantages as taxing was based on bore AREA. For a given cc size bore area was reduced by increasing stroke. This limited achievable RPM. Japanese engines had no such limits and I remember our amazement in the early days of Japanese motorcycles at the under-square high revving Japanese motorcycles - which gave them a power per cc rating advantage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly some America's cup yachts at one stage had their ratings improved by tacking light metal sheeting on their decks. This made NO difference whatsoever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example of stabiliser interaction in another field - many modern cameras have inbuilt motion stabilisers. These need to be turned off when the camera is used on a tripod - or else the compensation system causes the camera to &quot;hunt&quot; about the &lt;em&gt;essentially&lt;/em&gt; perfectly stable tripod. I've read of people who had major blur issues through failing to realise this. &lt;/p&gt;&#xA;" OwnerUserId="4371" LastEditorUserId="4371" LastEditDate="2015-12-15T05:22:41.503" LastActivityDate="2015-12-15T05:22:41.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23641" PostTypeId="2" ParentId="21431" CreationDate="2015-12-14T10:56:27.127" Score="1" Body="&lt;p&gt;The mass flow is approximately $20 \ldots 100~kg/s$.&lt;br&gt;&#xA;You can try to calculate it yourself using thermodynamic equations (see for example &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/turbth.html&quot; rel=&quot;nofollow&quot;&gt;NASA Resources&lt;/a&gt;, &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node85.html&quot; rel=&quot;nofollow&quot;&gt;MIT Resources&lt;/a&gt; or dedicated books).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the (idealized) calculations are not very difficult, please note that you will have to make a lot of assumptions concerning the efficiency of the turbojet components (particularly intake, compressor, combustion chamber, turbine and nozzle), since this data is not published by engine/airplane manufacturers. Some variables that are usually available are the thrust, the total compressor pressure ratio and maybe the (approximate) geometry of the intake and the nozzle.&lt;br&gt;&#xA;Also, you are asking for supersonic calculations, which are more complex than the subsonic ones -- including the assumptions.&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorDisplayName="user12485" LastEditDate="2015-12-14T11:12:14.990" LastActivityDate="2015-12-14T11:12:14.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23642" PostTypeId="1" AcceptedAnswerId="23645" CreationDate="2015-12-14T13:37:21.123" Score="19" ViewCount="6901" Body="&lt;p&gt;Airport ramps are close to level, not inclined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the history and etymology of this aviation term?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2015-12-14T23:09:51.830" Title="Why do we call it a ramp?" Tags="&lt;terminology&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23643" PostTypeId="2" ParentId="23603" CreationDate="2015-12-14T14:04:05.547" Score="3" Body="&lt;p&gt;The other answers are correct. The regulations do not require you to be solo in order to log PIC time or the landings for the currency. The only problem would arise would be if you are already outside of the 90 day currency window. At that point you would be required to complete the takeoffs and landings solo (meaning you are the sole occupant of the aircraft) or with a flight instructor occupying the other seat. A flight instructor is not considered a &quot;passenger&quot; when they are acting in the capacity of a flight instructor. Once those three takeoffs and landings are complete AND logged you may then carry passengers again. &lt;/p&gt;&#xA;" OwnerUserId="12489" LastActivityDate="2015-12-14T14:04:05.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23644" PostTypeId="2" ParentId="23632" CreationDate="2015-12-14T14:04:56.260" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.departedflights.com/&quot; rel=&quot;nofollow&quot;&gt;departedflights.com&lt;/a&gt; has a list of historical routes both by &lt;a href=&quot;http://www.departedflights.com/routemaps.html&quot; rel=&quot;nofollow&quot;&gt;airlines&lt;/a&gt; and (a few) &lt;a href=&quot;http://www.departedflights.com/airlinehubs.html&quot; rel=&quot;nofollow&quot;&gt;hubs&lt;/a&gt;. Though it is not complete, it has a lot of data.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-14T14:04:56.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23645" PostTypeId="2" ParentId="23642" CreationDate="2015-12-14T14:24:42.943" Score="23" Body="&lt;p&gt;Ramp refers to the area in airport where the aircraft are parked. This term comes from the days of seaplanes. From &lt;a href=&quot;http://flyingwithfish.boardingarea.com/2013/01/19/airport-lingo-ramp-vs-apron-vs-tarmac/&quot;&gt;this site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The term ‘Ramp‘ traces its roots back to the days of seaplanes when there literally was a ramp from the water to the terminal parking area. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In case of seaplanes, the area is actually an inclined plane between the shore and water. This is similar to the term boat ramp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this is used mainly in US. The ICAO (and FAA) terminology for the area is Apron.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-14T14:24:42.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23646" PostTypeId="2" ParentId="23495" CreationDate="2015-12-14T14:36:48.407" Score="5" Body="&lt;p&gt;There are a lot of things that can make the job of a airline pilot stressful.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The non flying duties of the job are the most stressful: Such as getting the airplane ready to push off the gate. Meaning all of the tests and checks and planning that must be done in possibly a 30 minute window. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scheduling: Every time they call you take a deep breath before answering the phone because you know that most likely, whatever they are planning to tell you, is going to screw up your plans for the day and possibly the week. Most pilots have a special ringtone set for their phone number to pre-warn them when its crew scheduling on the phone. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passengers: Its not that we don't like passengers we just get tired of them complaining about everything and slowing the embarkation and debarkation process. I fly regional jets and we always hear about how small the airplane is. Someone will inevitably argue with the flight attendant for five minutes that their bag, that is the size of a small child, will fit in our tiny overheads because it fit on their last flight. When asked about the aircraft they were on last we find out that it was a 787 on a international flight. I had a passenger 2 days ago ask me if I was a F18 pilot because he thought I braked to hard on the landing. Passengers will find whatever they can to complain about, its like a sick game for them. Now i'm not saying that all of them are bad, some passengers are very nice and grateful and will thank you for getting them there safely.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel: When we get our paperwork for a flight it tells us how much fuel is going to be put on the aircraft and how much we must have before we can take off. A lot of times this is just enough fuel to complete the flight with the FAA required reserve amounts. They do not like to give extra fuel because that means more money in fuel, the possibility of being weight restricted and having to leave passengers and bags behind, and its costs money to carry fuel because the heavier you are the more fuel you will use. Often times if we know we are going to be waiting for a while on the ground for takeoff or we decide that there is a possibility of us having to hold for a while in the air waiting to get cleared into a busy airport we have to call our dispatcher and ask for contingency fuel. This can be like pulling teeth sometimes. Its unbelievable that we have to argue with them to get more fuel on the aircraft because we think it will result in the safest outcome.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Being on time: Part 121 air carriers are big about being on time especially when you work for a fee for departure airline (most regionals are). We have a OUT time where we should be off the gate and they expect us to be off the gate no more than ten minutes early but not a minute late. Then we have a time that we are expected to arrive. They would like us to arrive either at the listed time or within 14 minutes after but not before the listed time and not 15 minutes late if we can help it. Then we have a computer system that tells us how fast we should fly to save fuel and money and make this all happen, it often gets ignored.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ATC Delays: ATC plays a large role in some of our stress. Things like ground stops and diversions make like fun. If a place like Newark NJ gets too busy they will ground stop meaning that anyone who is getting ready to go there who hasn't taken off yet is going to be sitting for a while until they clear up the traffic jam in the sky. We say for an hour and a half one night to takeoff to go there. This meant that the rest of our evening was delayed an hour and a half as well, evening getting to go to bed was delayed for us that night.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Commuting: As much as the public must think its awesome that we get to travel all the time it gets old really fast. We are often not based close to our homes which means we have to commute to work. Sometimes it is easy to get a seat and we have no problem. Other times all the flights are full and we have to try to squeeze in somewhere or hope that we can get the cockpit jumpseat. We don't mind sitting next to passengers on flights. However, we do mind when you try to make us your private source on everything aviation related. We don't mind answering a question or two but I don't want to sit there and explain the mechanics of a jet engine to you and explain to you why it is so turbulent. Also just because we are a pilot does not mean we know everything about every aircraft. Just because we are flying to Houston TX on a 737 does not mean that I fly that aircraft and know anything about it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Medical Examiners: As airline pilots we are required to see a medical examiner once per year to ensure that we are fit to fly. We are always worried about our health and whether or not they are going to find something small that would prevent us from flying. They are constantly changing the rules on us and its hard to keep track of them all, all of the time. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Next time you are on a commercial flight just remember that the crew is there to get you from point A to point B safely and efficiently. We all really do love what we do or we wouldn't be there because lets be honest...the pay isn't that great. Thank them for a nice ride and smile....they will appreciate it.&lt;/p&gt;&#xA;" OwnerUserId="12489" LastActivityDate="2015-12-14T14:36:48.407" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23647" PostTypeId="2" ParentId="23628" CreationDate="2015-12-14T15:01:51.030" Score="39" Body="&lt;p&gt;Short answer, yes.  However, it is important to note that the WSO is not a pilot.  The WSO is trained to operate the weapons systems, not fly the aircraft, but does have basic flight controls including throttle, stick, rudder pedals, compass, HSI, etc.  He does not have good forward visibility and would likely have to be talked in on final approach by the tower, as his view is obstructed by the pilot's seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the F-15E was developed from the D-model used for pilot training, the airframe was significantly redesigned for it's new purpose, and the back seat of an E-model bears only a passing resemblance to the back seat of a D-model.  The WSO has a very specific and complex set of tasks which does not include flying the airplane, and his controls are designed around that purpose.  He has more screens than the pilot to look at, and two side-stick controllers (not part of the flight control system) that are used for controlling / selecting / guiding / programming / etc. a large variety of weapons. He also has primary control over the FLIR and laser pods used for target designation and tracking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a final note, it is not uncommon (although less common in these days of sequestration) for non-aircrew personnel to be given 'incentive rides' in the back seat of aircraft like the F-15D/E or F-16D, and during these rides control of the aircraft is invariably passed to the passenger.  I was privileged enough during my Air Force career to get a ride in the back seat of an F-15E (tail number 88-1671 at Seymour Johnson AFB, NC) and can say from personal experience that it is possible to fly an F-15E from the back seat.  It was the most exhilarating 5 minutes of my life.  Fortunately for both of us, the pilot didn't experience any problems during the flight...&lt;/p&gt;&#xA;" OwnerUserId="12657" LastActivityDate="2015-12-14T15:01:51.030" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23648" PostTypeId="2" ParentId="53" CreationDate="2015-12-14T16:47:52.150" Score="5" Body="&lt;p&gt;The IACC navigation fees are approximately $170 for a small jet, plus there is a service fee to issue. There is a full list at &lt;a href=&quot;https://www.worldairops.com/permits/cuba.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;World Air Operations&lt;/a&gt; and you can in fact order the permit for Cuba online there too. &lt;/p&gt;&#xA;" OwnerUserId="12661" LastEditorUserId="-1" LastEditDate="2018-08-04T02:38:29.780" LastActivityDate="2018-08-04T02:38:29.780" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23650" PostTypeId="1" CreationDate="2015-12-14T18:41:56.497" Score="22" ViewCount="17777" Body="&lt;p&gt;Where did the term &lt;a href=&quot;https://en.wikipedia.org/wiki/Airport_apron&quot; rel=&quot;nofollow noreferrer&quot;&gt;apron&lt;/a&gt; come from?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/23642/8730&quot;&gt;Follow up question&lt;/a&gt; as suggested by @Pyritie. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-12-15T12:06:40.547" Title="Why do we call it an apron?" Tags="&lt;terminology&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23651" PostTypeId="1" AcceptedAnswerId="23657" CreationDate="2015-12-14T19:18:09.770" Score="7" ViewCount="7884" Body="&lt;p&gt;My meteorology textbook (from Pooley's &lt;em&gt;Air Pilot's Manual&lt;/em&gt; series) has a list of abbreviations used in met reports and forecasts. They include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;FG&lt;/em&gt; for &quot;fog&quot;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;BCFG&lt;/em&gt; for &quot;fog patches&quot;&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;PRFG&lt;/em&gt; for &quot;fog banks&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What's the difference between these three?&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-12-14T21:59:13.307" Title="What's the difference between fog, fog banks, and fog patches?" Tags="&lt;weather&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23652" PostTypeId="2" ParentId="23651" CreationDate="2015-12-14T20:18:41.537" Score="4" Body="&lt;ul&gt;&#xA;&lt;li&gt;BCFG is patches of fog (BC = BanCs, French origin)&lt;/li&gt;&#xA;&lt;li&gt;PRFG is partial fog, meaning that part of the aerodrome is covered in fog, but the coverage is  not extensive enough to qualify as fog (FG).  &lt;/li&gt;&#xA;&lt;li&gt;VCFG is fog in the vicinity of, but not on the airport&lt;/li&gt;&#xA;&lt;li&gt;MIFG is shallow fog (MI = mince, French origin) &lt;/li&gt;&#xA;&lt;li&gt;FZFG is freezing fog&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-12-14T20:18:41.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23653" PostTypeId="2" ParentId="23650" CreationDate="2015-12-14T20:22:24.247" Score="9" Body="&lt;p&gt;&lt;em&gt;Apron&lt;/em&gt; may be the result of a wrong translation from French vocabulary (France had an active role in aviation history).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The circulation area of a bridge is named &lt;em&gt;tablier&lt;/em&gt; (&lt;em&gt;roadway&lt;/em&gt;) in French. Actually &lt;em&gt;tablier&lt;/em&gt; is used to designate many flat engineered surfaces (it comes from Latin &lt;em&gt;tabula&lt;/em&gt;, &lt;em&gt;table&lt;/em&gt;).&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/pU37C.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pU37C.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Tablier&lt;/em&gt; is also the &lt;em&gt;apron&lt;/em&gt;, the overall used for housework.&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CKARC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CKARC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I suspect the intent of the translation was to use the flat area meaning, but the other sense was used and &lt;em&gt;apron&lt;/em&gt; was wrongly retained for the equivalent of a flat area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In French the airfield &lt;em&gt;apron&lt;/em&gt; is &lt;em&gt;aire de stationnement&lt;/em&gt; (&lt;em&gt;parking area&lt;/em&gt;) but &lt;em&gt;tarmac&lt;/em&gt; is also common in medias.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-12-14T21:10:27.100" LastActivityDate="2015-12-14T21:10:27.100" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23654" PostTypeId="1" AcceptedAnswerId="23655" CreationDate="2015-12-14T20:22:47.373" Score="30" ViewCount="6618" Body="&lt;p&gt;Let's say there was a two-person jet (take the F-15 for example) that was involved in some sort of accident in the air that incapacitated the pilot (unconscious but still alive) and left the aircraft unflyable. Could the copilot eject his fellow pilot in an attempt to save his/her life from the inevitable crash that would eventually take place? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some sort of system in the aircraft that would do this automatically? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems like an messy problem to have. On one hand you don't want to be blasted out the windshield accidentally by your copilot or faulty computer system but on the other hand it sure would be nice to survive in the off chance you are unable to exit the plane yourself.   &lt;/p&gt;&#xA;" OwnerUserId="1824" LastEditorUserId="1467" LastEditDate="2017-12-14T08:44:06.717" LastActivityDate="2019-04-24T11:16:10.640" Title="Can someone/something other than the pilot trigger the ejection seat?" Tags="&lt;military&gt;&lt;jet&gt;&lt;fighter&gt;&lt;ejection-seat&gt;" AnswerCount="6" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23655" PostTypeId="2" ParentId="23654" CreationDate="2015-12-14T20:59:39.490" Score="40" Body="&lt;p&gt;In a word, yes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a switch which controls this and the default position is &quot;both&quot;.  If any handle is pulled (pull down over the face or the one between your legs), then both seats fire.  If solo, the switch is turned to &quot;solo&quot; so that the rear seat is not ejected and the front seat gets to leave a little bit quicker.  If the switch is left on solo, and both seats are occupied, then each crew member can eject on their own.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You would also have if set to &quot;solo&quot; with an untrained passenger in the back.  You wouldn't want someone getting a bit excited and firing them both out of a perfectly working jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/22377/why-is-the-rear-seat-ejected-before-the-front-one?rq=1&quot;&gt;See this question&lt;/a&gt; about what happens, &lt;a href=&quot;https://aviation.stackexchange.com/questions/12821/what-are-these-wavy-lines-on-fighters-canopy/12822#12822&quot;&gt;and this one&lt;/a&gt; to understand why you won't hit the canopy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, there is no computer controlled ejection system.  I don't think anyone would trust it to know better than the crew when it's time to bail out.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-12-14T21:05:39.927" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23656" PostTypeId="2" ParentId="23347" CreationDate="2015-12-14T21:38:33.857" Score="5" Body="&lt;p&gt;The problem is that you're using the Flight Operations Manual, and not the Schematic Manuals. Quite frankly, FOM's pretty much suck in terms of technical details, but that's not their purpose either. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In regards to your question about what the channels are: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Channels are really just a euphemism for system redundancy. The FAC's are two completely separate entities (with crosstalk capabilities) - kind of like flight crews. The PIC (pilot-in-command) has primary control of the aircraft, while the SIC (second-in-command) has the same independent authority. The PIC and SIC can talk to one another, and monitor what each is doing. If the PIC falls ill, becomes incapacitated, etc.. the SIC can take over the functions of the PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAC's work the same way. They both receive the same information, and have full capability of performing the work of one another. Take note of this schematic, courtesy of Airbus (&lt;a href=&quot;http://www.gerryairways.com/index.php/tag/accident/&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;found on the web&quot;&gt;found on the web&lt;/a&gt;), and which I took the liberty of highlighting:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9mC8P.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9mC8P.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, what this schematic is saying is that the ELAC's, under normal law, provide turn coordination and dutch roll damping to the FAC's. They do this by receiving inputs from the rudder pedals, sidesticks, FMGC's, ADIRU's, SFCC, LGCIU's, and hyd pressure. Based on those inputs, it computes the proper yaw commands and sends that to the FAC's. It should be noted that both FAC's receive the same information on, you guessed it, separate channels. What does that mean? The data from ELAC 1 is sent to BOTH FAC's on separate sets of wires. Inside the FAC's, those data paths are split as well (Channel A &amp;amp; Channel B) and a separate processor computes the data on Channel A &amp;amp; the data on Channel B. Never the two shall meet. Likewise, the data from ELAC 2 is sent to BOTH FAC's on separate sets of wires, and again, those two data paths shall never meet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, both FAC's are receiving the same FMGC, ADIRU, SFCC, LGCIU data that the ELAC is. Again... Separate wires, separate outputs, and computed with two different processors inside the boxes. The FAC's are also receiving hydraulic pressure, commanded rudder trim position, and SEC fault data. Guess what? All on different channels. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, take note of the highlighted portion in red. Ordinarily, FAC 1 is in control of the servo loop for the RTL Motors. This essentially means that based on ALL of the inputs received from the ELAC's and other independent systems, the FAC 1 sends a signal to the rudder travel motor and says &quot;Move here.&quot; The motor moves, and a feedback signal from the RTLU circuitry is sent to the FAC saying &quot;Here I am.&quot; When the commanded position of the surface position minus the actual position of the surface is approximately ~0, the surface is nulled. This is a basic feedback loop/servoloop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAC 2 has the exact same capabilities as FAC 1. The two are in constant communication, making sure that neither has failed. If FAC 1 reports a self-failure, or FAC 2 detects a problem with FAC 1 and/or its servo loop, FAC 2 can immediately take over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that FAC 2 is responsible for the M2 (second motor) of the rudder travel limit system, and FAC 1 is responsible for the M1 (primary motor) of the rudder travel limit system. The wiring for the motors and its associated servo loop are completely separate. Again, the idea is complete system isolation. As such, any one failure cannot take out the entirety of a system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of the above is under the presumption of NORMAL LAW. It appears that cracked solder joint&lt;strong&gt;s&lt;/strong&gt;, emphases on the plural form, caused failures of Channel A &amp;amp; Channel B of the RTLU (see page 66 of accident report). Basically, like I mentioned previously, FAC 2 was monitoring FAC 1 for faults with it or its associated servo loop. When RTL channel A failed (the servo loop feeding data back to FAC 1; associated with Motor 1), the FAC 2 picked up on it, and took over on its own separate channel. A cracked solder joint on RTL channel B caused FAC 2 to trigger a failure. At some point during these failures, the flight crew pulled the circuit breakers, presumably to reset the faults. The loss of both FAC's put the aircraft into alternate law.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft was in alternate law, it seemed that there was a lot of confusion as to what was happening. From there, things went from bad to disastrous. &lt;/p&gt;&#xA;" OwnerUserId="12452" LastEditorUserId="12452" LastEditDate="2015-12-14T23:51:19.927" LastActivityDate="2015-12-14T23:51:19.927" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23657" PostTypeId="2" ParentId="23651" CreationDate="2015-12-14T21:59:13.307" Score="8" Body="&lt;p&gt;Thanks to mins's link, the &lt;a href=&quot;https://bmtc.moodle.com.au/mod/book/view.php?id=2173&amp;amp;chapterid=60&quot;&gt;Australian Government Bureau of Meteorology&lt;/a&gt; explains everything in detail. To summarise the particular part I was asking about:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FG on its own means fog (visibility &amp;lt; 1000 m) covers &lt;strong&gt;more than half&lt;/strong&gt; of the horizon&lt;/li&gt;&#xA;&lt;li&gt;PRFG and BCFG are fog covering &lt;strong&gt;less than half&lt;/strong&gt; of the horizon&lt;/li&gt;&#xA;&lt;li&gt;PRFG (fog bank) is &lt;strong&gt;more extensive&lt;/strong&gt; than BCFG (fog patches)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Another way of looking at it is like cloud cover descriptors. FG is like BKN or OVC: more than half the horizon is covered. PRFG is SCT, and then BCFG is FEW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the above are used when the temperature is above freezing point and the fog reaches more than 2 metres above ground. If the fog is only below 2 metres agl, it's shallow fog &lt;em&gt;MIFG&lt;/em&gt; instead. If the temperature is below freezing, so the fog consists of supercooled water droplets, it's freezing fog &lt;em&gt;FZFG&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2015-12-14T21:59:13.307" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23658" PostTypeId="1" CreationDate="2015-12-14T22:21:23.607" Score="5" ViewCount="250" Body="&lt;p&gt;Suppose you are on a day VFR flight and you are testing your aircraft lights. If you discover that the bulb for one of your nav lights is blown, then you can turn the switch off and tape it off, placard it as inop, and fly anyway. However, if you don’t placard it, my understanding is that you are not legal to fly, even if it is day VFR and you leave the switch off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question: should you avoid testing unnecessary equipment? Presumably if you did not test the nav lights during your preflight (not intending to use them) then you never knew they were broken, therefore you didn’t need to turn off and placard as inop. What is best-practice here? My question is specifically about nav lights, but I am also interested in other optional equipment (eg an autopilot).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is in the USA as a Part 91 flight.)&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="639" LastEditDate="2015-12-14T23:00:47.860" LastActivityDate="2015-12-15T17:51:29.170" Title="Should I avoid testing unnecessary equipment?" Tags="&lt;faa-regulations&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23659" PostTypeId="2" ParentId="23642" CreationDate="2015-12-14T23:09:51.830" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://boards.straightdope.com/sdmb/showthread.php?t=618158&quot;&gt;boards.straightdope.com/sdmb/showthread.php?t=618158&lt;/a&gt; - first post by LSLGuy:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The surface used to get seaplanes in and out of the water actually was&#xA;  called a &quot;sea plane ramp&quot; since when they were leading edge aviation&#xA;  tech. The few survivors are still called &quot;seaplane ramp&quot;s today. And&#xA;  the ramp part refered to the fact it's an inclined plane between two&#xA;  levels, shore &amp;amp; water.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As sea planes gave way to land planes I'd bet ramp got appropriated&#xA;  for the concrete surface in front of the terminal. Remembering this&#xA;  was all happening in an era where nothing was paved unless it had to&#xA;  be; grass was the default surface for everything.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;As to apron ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Waay back in the day, airports were simply 1/2 mile or 3/4 mile&#xA;  squares of flat grass-covered former farm field with a small terminal&#xA;  building in one corner. Planes landed &amp;amp; took off on the grass, and&#xA;  parked in front of the building to load &amp;amp; unload.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Given the reality of rain &amp;amp; snow, the area in front of the building&#xA;  would get muddier faster thatn the rest of the field. Between plane&#xA;  traffic, fuel truck traffic, cargo wagon traffic &amp;amp; passengers (&amp;amp;&#xA;  horses), churning the surface to mud would be pretty much a sure&#xA;  thing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A pretty obvious innovation would be to pave a more-or-less fan-shaped&#xA;  area in front of the building where the airplanes could park.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Which when viewed from above, would look like an apron; a protective&#xA;  semi-circular wrap around the working side of a person. Sorta like the&#xA;  way the dirt area of a traditional baseball diamond looks with the&#xA;  terminal building being at home plate.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;My pet peeve in aviation terminology is &quot;tarmac&quot; for the aircraft&#xA;  parking area of an airport. Somehow the word finds its way into every&#xA;  news article about airline ops.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;Tarmac&quot; is simply a synonym for &quot;asphalt&quot;. Back in 1930 or whenever,&#xA;  it would have made sense to refer to the paved area as such. &quot;The&#xA;  mighty DC-3 pulled up onto the asphalt; soon the crowd would greet the&#xA;  celebrities&quot;, etc. &quot;Asphalt&quot; in this sentence meaning the paved&#xA;  parking area in the otherwise grass airport.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;But in 2011? Please newspeople, give &quot;tarmac&quot; the decent burial it&#xA;  deserves.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In the business in the US, we call it the ramp. I don't know of anyone&#xA;  who uses another term. Some Canadian airports call it the apron.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12665" LastActivityDate="2015-12-14T23:09:51.830" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23660" PostTypeId="2" ParentId="23650" CreationDate="2015-12-14T23:37:17.763" Score="15" Body="&lt;p&gt;Airport apron refers to the area of an airport where aircraft are parked, unloaded or loaded, refueled, or boarded and looks like this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jXUJc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jXUJc.jpg&quot; alt=&quot;Apron&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from airplane-pictures.net&lt;/p&gt;&#xA;&lt;p&gt;This probably originated from the word defining &lt;a href=&quot;http://www.wordorigins.org/index.php/forums/viewthread/330/&quot; rel=&quot;noreferrer&quot;&gt;theatrical apron&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;1903 A. B. WALKLEY Dramatic Criticism 108 The ‘apron’ is the technical name for the stage-area in front of the curtain. In the Elizabethan theatre it jutted right out among the public, who surrounded it on three sides. This ‘apron’ slowly shrank..till at last in our day it has altogether disappeared.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As the airport apron looks similar to this, it probably go its name. The following image shows an apron stage (The Visy Theatre in &lt;a href=&quot;http://www.gtaust.com/news_item/category/live/id/333/DiGiCo%20Proves%20its%20Power%20at%20the%20Powerhouse%20Theatre&quot; rel=&quot;noreferrer&quot;&gt;Brisbane Powerhouse&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6vrPQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6vrPQ.jpg&quot; alt=&quot;Apron&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from gtaust.com&lt;/p&gt;&#xA;&lt;p&gt;As for &lt;em&gt;why&lt;/em&gt; its like this, the &lt;a href=&quot;http://boards.straightdope.com/sdmb/showthread.php?t=618158&quot; rel=&quot;noreferrer&quot;&gt;following explanation&lt;/a&gt; seems the most plausible:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Waay back in the day, airports were simply 1/2 mile or 3/4 mile squares of flat grass-covered former farm field with a small terminal building in one corner. Planes landed &amp;amp; took off on the grass, and parked in front of the building to load &amp;amp; unload.&lt;/p&gt;&#xA;&lt;p&gt;Given the reality of rain &amp;amp; snow, the area in front of the building would get muddier faster thatn the rest of the field. Between plane traffic, fuel truck traffic, cargo wagon traffic &amp;amp; passengers (&amp;amp; horses), churning the surface to mud would be pretty much a sure thing.&lt;/p&gt;&#xA;&lt;p&gt;A pretty obvious innovation would be to pave a more-or-less fan-shaped area in front of the building where the airplanes could park.&lt;/p&gt;&#xA;&lt;p&gt;Which when viewed from above, would look like an apron&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As for tarmac, it is simply a synonym for Asphalt, which was used in apron's construction.&lt;/p&gt;&#xA;&lt;p&gt;Note: The historical term apron bears similarities to modern ramp, as in 'walk the ramp'&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-15T12:06:40.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23661" PostTypeId="2" ParentId="23654" CreationDate="2015-12-14T23:59:39.277" Score="18" Body="&lt;p&gt;Yes. In general, the Weapons System Officer (WSO) can initiate ejection sequence and usually has control over it (of course it varies from aircraft to aircraft). From the &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/an-elite-f-14-airman-explains-why-the-tomcat-was-so-imp-1610043625&quot;&gt;interview of LCDR Joe &quot;Smokin&quot; Ruzicka&lt;/a&gt;, a F-14 Radar Intercept officer (RIO):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Both crew member's &lt;em&gt;[sic]&lt;/em&gt; relied on each other- even down to the RIO having control of the ejection sequence- because conventional wisdom said the pilot would want to stay with the jet until it was too late. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Automatic ejection systems are rare, because you want the pilot to have control over when to eject (automatic ejection is considered a bad thing). However, it is found in a few aircraft, like the Soviet &lt;a href=&quot;https://en.wikipedia.org/wiki/Yakovlev_Yak-38&quot;&gt;Yak-38&lt;/a&gt;, a VTOL aircraft. Once the aircraft rolled past 60 degrees in case of engine failure, ejection sequence was initiated automatically. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="12099" LastEditDate="2015-12-15T00:39:02.590" LastActivityDate="2015-12-15T00:39:02.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23662" PostTypeId="1" CreationDate="2015-12-15T01:45:39.633" Score="5" ViewCount="198" Body="&lt;p&gt;I need help identifying a Boeing 727 maintenance task that would be suitable for a research project on improving maintenance instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, the task should meet the following criteria:&#xA;- the task should take about 1 hour to complete in a base maintenance environment;&#xA;- the task should have a safety risk that is prone to human error (for example, potential to do an incorrect installation of a component).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is for a research proposal to improve the quality of maintenance instructions. I have a commercial aviation training school that is interested in participating. They have a 727 which is a type I've never worked on and I don't have access to any of the 727 manuals either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm trying to table several options that I can put to the school. What I have so far is removal/installation of an AC generator or perhaps the generator constant speed drive. Further suggestions would be very much appreciated!&lt;/p&gt;&#xA;" OwnerUserId="12666" LastEditorUserId="19" LastEditDate="2016-07-08T11:26:34.597" LastActivityDate="2016-07-08T11:26:34.597" Title="Can you help me to identify a Boeing 727 maintenance task involving a safety risk for a research project?" Tags="&lt;boeing&gt;&lt;aircraft-maintenance&gt;&lt;human-factors&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23663" PostTypeId="2" ParentId="23658" CreationDate="2015-12-15T01:51:33.900" Score="4" Body="&lt;p&gt;It is the job of the pilot in command to verify the aircraft is in an airworthy state before flight.  If you chose to not test &quot;optional&quot; equipment you would still be illegal if that equipment was inoperative.  You are required to follow 91.213 if that equipment is inoperative whether or not you found out about it.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-12-15T01:51:33.900" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23664" PostTypeId="2" ParentId="23563" CreationDate="2015-12-15T02:20:56.620" Score="2" Body="&lt;p&gt;When Boeing first designed the 737, their focus was to reduce weight by having a short and simplified landing gear. This affected how the JT8Ds were fitted to the wings (directly underneath, no pylons) and introduced the design and associated issues that @aeroalias has explained so well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was only when the 737-300 was being designed to have the larger (read quieter and more efficient) CFM engines that the engine position was changed (from directly under wing to slightly forward of it), and allowed Boeing the opportunity to do away with the cone pins.&lt;/p&gt;&#xA;" OwnerUserId="12666" LastActivityDate="2015-12-15T02:20:56.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23665" PostTypeId="2" ParentId="16121" CreationDate="2015-12-15T02:37:50.383" Score="2" Body="&lt;p&gt;In the words of Benjamin Disraeli, there are three kinds of lies... Lies, Damn Lies, and Stastistics! As Dave has already mentioned, the devil is in the detail. I support his assumption that the 20 maintenance man-hour figure is an overall average.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By way of comparison, I often quote a figure of 12 maintenance man hours per flight hour. This is from an Australian Transport Safety Bureau paper written by Dr Alan Hobbs. He doesn't delve into the basis of this figure, so I have assumed it to be an industry wide, overall figure. In this context, I think that the 20 man-hours you cite for the C17 is entirely believable, being a complex, military aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FYI, Dr Hobb's paper - An Overview of Human Factors in Aviation Maintenance - can be viewed via &lt;a href=&quot;https://www.atsb.gov.au/media/27818/hf_ar-2008-055.pdf&quot; rel=&quot;nofollow&quot;&gt;this ATSB link&lt;/a&gt;:&lt;/p&gt;&#xA;" OwnerUserId="12666" LastEditorUserId="19" LastEditDate="2016-07-14T08:39:54.460" LastActivityDate="2016-07-14T08:39:54.460" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23666" PostTypeId="2" ParentId="69" CreationDate="2015-12-15T02:54:23.470" Score="2" Body="&lt;p&gt;I know this is an old question but wanted to share my experience with you. The short answer to your first question is: yes, airlines still use task cards in maintenance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;True, information technology has come along in leaps and bounds. Many airlines have leveraged technology in how they produce their task cards, but ultimately, most still rely on paper. The primary reason for this is that each task needs to be signed off by an appropriately licensed engineer, and the task card then becomes a legal document. Since airlines are increasingly outsourcing their maintenance all over the world, until digital sign-offs are widely accepted in the industry, it doesn't make sense for the airline alone to go fully digital.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is changing, but due to the highly regulated nature of the industry, innovation can take time to trickle down.&lt;/p&gt;&#xA;" OwnerUserId="12666" LastActivityDate="2015-12-15T02:54:23.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23667" PostTypeId="2" ParentId="2061" CreationDate="2015-12-15T03:14:10.247" Score="2" Body="&lt;p&gt;I am an Aviation Maintenance student.  The way my instructor explained it to me was: any time that you exceed 70% RPM, you have just run an engine cycle.  It is more about acknowledging that the engines reached a certain temperature and was exposed to stresses that maintenance should know about.  Different engine manufacturers will probably have different definitions of a cycle.&lt;/p&gt;&#xA;" OwnerUserId="12667" LastEditorUserId="7532" LastEditDate="2015-12-15T04:24:51.987" LastActivityDate="2015-12-15T04:24:51.987" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23668" PostTypeId="2" ParentId="23662" CreationDate="2015-12-15T03:34:48.927" Score="8" Body="&lt;p&gt;It's been a while since I worked the 727. It was a very forgiving airplane, so you had to do a lot to make a critical safety error from a maintenance perspective. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I do remember elevator position transmitters being a major pain to adjust. Although the manual wasn't necessarily bad, I never felt comfortable with the adjustments because of how sensitive they were. The manual made it sound so easy, when in all reality, I would have felt better if there was some note that said something to the effect of &quot;this may take a while.&quot; Plus, you always had Skydrol dripping in your face when doing it off a lift in the howling wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even tightening the bolt of the transmitter down was enough to bring it out of tolerance. So, ordinarily, you had to rig it out of tolerance, then hope that the tightening of the bolt brought it in tolerance. Sometimes it'd take 5 minutes. Other times it could take all night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a &quot;dog bone&quot; that attaches between the transmitter and the flight control surface. Sometimes the bearings in that dog bone would develop slop, and cause autopilot issues as well. &lt;/p&gt;&#xA;" OwnerUserId="12452" LastActivityDate="2015-12-15T03:34:48.927" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23669" PostTypeId="2" ParentId="23654" CreationDate="2015-12-15T04:41:38.520" Score="9" Body="&lt;p&gt;Not really an answer to the text and intent of the question, but with regard to the question as asked in the title (&quot;Can someone/something other than the pilot trigger the ejection seat?&quot;), I'll share a story that a friend who flew AWACS told me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He was flying somewhere in the Middle East, and a Navy jet pulled up close enough to wave at the AWACS pilots, who weren't particularly amused.  Not knowing what frequency the Navy fighter was monitoring (if any), my friend in the left seat of the AWACS picks up his microphone, switches to Guard (which everybody monitors), and transmits something along the lines of, &quot;Dude, we're putting out enough RF energy to &lt;strong&gt;&lt;em&gt;launch&lt;/em&gt;&lt;/strong&gt; your &lt;strong&gt;&lt;em&gt;seat&lt;/em&gt;&lt;/strong&gt; at that distance!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fighter peeled off in great haste.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, something other than the pilot/s of the aircraft CAN potentially trigger the ejection seat.  I don't know how often this sort of thing has actually played out, but it has got to be an &quot;oh, ****&quot; moment if/when it ever did.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-15T04:41:38.520" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="23670" PostTypeId="1" AcceptedAnswerId="23671" CreationDate="2015-12-15T05:12:49.970" Score="1" ViewCount="545" Body="&lt;p&gt;Military Training Routes (MTRs) with no segment above 1,500' AGL shall be identified by four number characters (IR1206/VR1207)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MTRs that include one or more segments above 1,500' AGL shall be identified  with three number characters (IR206/VR207).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;What is the meaning of &lt;strong&gt;segment&lt;/strong&gt; in MTRs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the &lt;strong&gt;difference&lt;/strong&gt; between three and four?&lt;/p&gt;&#xA;" OwnerUserId="12668" LastEditorUserId="62" LastEditDate="2015-12-15T13:12:26.643" LastActivityDate="2015-12-15T13:12:26.643" Title="What is the meaning of segment in MTRs?" Tags="&lt;military&gt;&lt;usa&gt;&lt;terminology&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23671" PostTypeId="2" ParentId="23670" CreationDate="2015-12-15T05:54:03.040" Score="4" Body="&lt;p&gt;A &lt;strong&gt;route&lt;/strong&gt; is how you go from place to place.  A &lt;strong&gt;segment&lt;/strong&gt; is a portion of your route which is characterized by a consistent course/altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A route may have one segment, or many.  An MTR is a Military Training &lt;strong&gt;Route&lt;/strong&gt;.  If no portions of the route exceed 1,500 AGL, then it is given a four-digit identifier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm pretty sure that the three-digit / four-digit decision was arbitrary, but I'm ready to be educated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wSX0B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wSX0B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2015-12-15T05:54:03.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23672" PostTypeId="1" AcceptedAnswerId="23680" CreationDate="2015-12-15T06:04:30.020" Score="11" ViewCount="1190" Body="&lt;p&gt;I'm looking at filing out an 8050-1 for a new airplane in the US and the FAA is asking me for my name, and address. My concern is that once I register these bits of information, specifically my home address, become publicly available. So I'm wondering is there anyway of registering an aircraft tag in a way that keeps that information private? Are there any proxy registration services that exist for this purpose?&lt;/p&gt;&#xA;" OwnerUserId="12669" LastEditorUserId="62" LastEditDate="2015-12-15T12:32:35.607" LastActivityDate="2019-05-26T20:18:54.990" Title="How do I keep my home address private following new aircraft registration?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23673" PostTypeId="1" AcceptedAnswerId="23677" CreationDate="2015-12-15T06:33:10.053" Score="0" ViewCount="384" Body="&lt;p&gt;This is for a sci-fi story I'm writing, so the answer doesn't have to be perfect, just close as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the lift fans on a F-35 be driven by a turboshaft instead of the jet engine If yes, which one? The jet engine that drives the lift fans in a F-35 is called Pratt &amp;amp; Whitney F135  engine. The engine dumps 20,000 shaft horsepower onto  shaft that spins the fans. But i need a way to do this with a turbine, not jet engine with thrust coming from the rear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm assuming that it takes a certain amount of shp (shaft horsepower) to spin the lift fans at the correct rpm.  The fictional vtol is to have 4 lift fans driven by four turbine with little heat signature to avoid infrared.&lt;/p&gt;&#xA;" OwnerUserId="12670" LastEditorUserId="12670" LastEditDate="2015-12-15T06:43:44.770" LastActivityDate="2015-12-15T10:32:48.990" Title="Can the lift fans used on a F-35 be driven by a turboshaft engine instead of the jet engine? If yes, which one?" Tags="&lt;aircraft-design&gt;&lt;turbine&gt;&lt;vtol&gt;&lt;f-35&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-12-15T11:22:16.053" ContentLicense="CC BY-SA 3.0" />
  <row Id="23674" PostTypeId="2" ParentId="23654" CreationDate="2015-12-15T06:44:16.393" Score="9" Body="&lt;p&gt;The question as to whether other crew members can trigger the ejection sequence has been answered.&lt;br/&gt;&#xA;As to whether there can be automated systems that do it, the answer to that is a resounding &quot;yes&quot; as well.&lt;br/&gt;&#xA;The Yak-38 VTOL fighter of the Soviet navy had just such a system and they were considered for other types as well (but afaik never installed for reasons that will become clear).&lt;br/&gt;&#xA;This system worked. In fact it worked too good. It had a tendency to eject the pilot even when there was nothing wrong with the aircraft, causing more than a few aircraft losses and injured pilots as a result.&lt;br/&gt;&#xA;A system like that monitors the aircraft parameters and systems and when they go out of normal operational ranges for a certain period triggers the ejection sequence. With the Yak at least, it appears that putting the aircraft into a hover to land it would sometimes trigger the ejection, oops :)&lt;/p&gt;&#xA;" OwnerUserId="900" LastActivityDate="2015-12-15T06:44:16.393" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23675" PostTypeId="1" AcceptedAnswerId="23679" CreationDate="2015-12-15T08:41:47.197" Score="12" ViewCount="2028" Body="&lt;p&gt;I'm generally speaking about airports with runways long enough for airliners, be historic or still in use. In order not to turn this question to a chicken-egg discussion, here are my points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Would making an airport(s) before making the actual airplanes be&#xA;feasible and cost-efficient ? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Will new(and more runway-length&#xA;demanding) airplanes be able to take-off from shorter runways,&#xA;because there are no other options ?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm generally interested in historic terms, which came to be first - bigger airplanes, or longer runways ?&lt;/p&gt;&#xA;" OwnerUserId="11787" LastEditorUserId="11787" LastEditDate="2015-12-15T11:35:09.710" LastActivityDate="2015-12-15T21:08:10.937" Title="Which came to be first - bigger airplanes, or longer runways?" Tags="&lt;airliner&gt;&lt;aviation-history&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23676" PostTypeId="1" AcceptedAnswerId="23686" CreationDate="2015-12-15T09:25:14.323" Score="12" ViewCount="481" Body="&lt;p&gt;Someone said a canard wing is more prone to icing than a stabilizer. If true, what would explain this?&lt;/p&gt;&#xA;" OwnerUserId="1344" LastEditorUserId="1696" LastEditDate="2015-12-15T21:23:50.323" LastActivityDate="2017-10-13T07:02:16.803" Title="Why would a canard wing be more prone to icing than a stabilizer?" Tags="&lt;aerodynamics&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23677" PostTypeId="2" ParentId="23673" CreationDate="2015-12-15T10:27:26.030" Score="3" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;There is no difference between turbofan, turboprop and turboshaft engine except for what is mounted on the shaft. There are many cores that are used in all of turbofan, turboprop and turboshaft engines. So yes, they can be driven by turboshaft. In a sense, the engine that drives them qualifies as turboshaft simply because it drives them.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;That said, the lift fan of F-35 is &lt;strong&gt;absurdly inefficient&lt;/strong&gt;. The thing is that lift is equal to mass flow through the fan/propeller times change of speed of the air, but the power required is equal to mass flow times &lt;em&gt;square&lt;/em&gt; of change of speed, plus drag that grows with RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the fan is small, so it has small mass flow and so it needs to accelerate the air to great speed and to do that it also needs high rpm, both greatly increasing the power required to spin it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-35 can live with that, because it only spends very short time in hover and a lot of time at high speed, so it can trade efficiency at hover for low drag at speed. But anything that should work like a helicopter should better have a large rotor like a helicopter, because it takes much less power to spin it (and thus has much lower fuel consumption).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2015-12-15T10:32:48.990" LastActivityDate="2015-12-15T10:32:48.990" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23678" PostTypeId="2" ParentId="23675" CreationDate="2015-12-15T12:49:57.673" Score="5" Body="&lt;p&gt;The bigger airplanes came first. A shortish runway length is not preventing bigger planes to operate, but it limits the take-off weight, especially in warm weather. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since a lower take-off weight means less payload, the business case to extend runways became obvious. So airports follow suit.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2015-12-15T12:49:57.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23679" PostTypeId="2" ParentId="23675" CreationDate="2015-12-15T13:07:55.210" Score="10" Body="&lt;p&gt;It is the larger aircraft that came first. Historically, the runway length (and design) of an airport has depended on the aircraft operating there (among other things), though this is changing. For example, the &lt;a href=&quot;http://www.prg.aero/en/prague-airport/parallel-runway/history/&quot;&gt;Prague airport site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The main runways – RWY 04/22 and RWY 13/31 – were continually lengthened during post WW II operations which kept them in line with the demands of the aviation industry until the mid 1960s... &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The runway required for the aircraft depends on the take-off weight and the lesser runway length restricts the payload or range. As a result, for economical operation, the runway needs to be longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are other constraints to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For large aircraft, the runway (and taxiway) width, apron and parking space are important considerations. In most cases, lengthening the runway will be easier than taking care of these other constraints.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the end, airports have to weigh the benefits of letting heavier aircraft operate against the resources required for runway lengthening. For major airports (like Heathrow, for example), the cost of runway expansion will run into the billions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Unless the aircraft is going to be operated regularly (which depends on how many airports it can land), there is no point in lengthening the runway in an airport.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The economic operation of the aircraft has to be considered. For example, the A380 was designed around a 80m 'box', which the airlines had decided is the maximum size they can operate economically.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A bigger aircraft does not mean more runway required. For example, the A380 requires (slightly) lesser runway compared to 747-400.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If it comes to that, aircraft requiring more runway can takeoff from smaller ones. For example, a Boeing Dreamlifter once &lt;a href=&quot;http://www.cnbc.com/2013/11/21/uh-oh-dreamlifter-lands-at-wrong-airport.html&quot;&gt;took off from a 6000 ft&lt;/a&gt; runway (it normally requires &gt; 9000ft).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The airports with longest runways have them for different reasons- the Qamdo Bamda Airport (5500m runway) has a long runway due to its elevation (&gt;4300m above MSL), while the Ramenskoye Airport as a long runway (5400m) due to the aircraft operated there; it was a test facility, for among other things, the Soviet Buran spacecraft.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-15T13:07:55.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23680" PostTypeId="2" ParentId="23672" CreationDate="2015-12-15T13:11:18.090" Score="12" Body="&lt;p&gt;The 'usual' alternative is to have the aircraft owned by a legal entity like an &lt;a href=&quot;https://en.wikipedia.org/wiki/Limited_liability_company&quot; rel=&quot;nofollow noreferrer&quot;&gt;LLC&lt;/a&gt; or trust of some kind (trusts are also used by &lt;a href=&quot;https://aviation.stackexchange.com/q/21080/62&quot;&gt;foreigners who own N-reg aircraft&lt;/a&gt;). But that only adds a layer of obfuscation: if someone really wants to know who owns the aircraft then they can dig into the LLC or trust ownership details. That information is usually also public although it's at the state level not federal level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best thing here is to talk to an attorney in your state, preferably one with aviation experience. He can tell you what legal entities might fit your needs, as well as the pros, cons and costs of each one.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-15T13:11:18.090" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23681" PostTypeId="1" AcceptedAnswerId="23693" CreationDate="2015-12-15T13:46:40.903" Score="10" ViewCount="1770" Body="&lt;p&gt;I was reading about the F-35 flight tests and it mentions a &quot;departure&quot; at a couple of places. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does that word mean in this context? I understand spins and stalls but what's a &quot;departure&quot;?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;AF-2 was the first F-35 to be flown to 9g+ and -3g, and to roll at&#xA;  design-load factor. Departure/spin resistance was also proven during&#xA;  high angle-of-attack (AOA) testing which eventually went as high as&#xA;  110 deg. AOA&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pilots really like maneuverability, and the fact that the aircraft&#xA;  recovers so well from a departure allows us to say [to the designers&#xA;  of the flight control system laws], ‘you don’t have to clamp down so&#xA;  tight,&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot;&gt;Lockheed Martin F-35 Lightning II&lt;/a&gt; article)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="3201" LastEditDate="2015-12-17T20:39:38.253" LastActivityDate="2015-12-17T20:39:38.253" Title="What is a &quot;departure&quot; in the context of flight testing / maneuvers?" Tags="&lt;military&gt;&lt;flight-testing&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23682" PostTypeId="2" ParentId="23658" CreationDate="2015-12-15T13:51:57.813" Score="6" Body="&lt;p&gt;The best practice is to pre-flight everything for every flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you have different pre-flight procedures for different situations then sooner or later you'll use the wrong one and miss something that you should have found. Consistency is really helpful in procedures.&lt;/li&gt;&#xA;&lt;li&gt;Even if something isn't needed for the flight, checking everything gives you an accurate picture of the state of the aircraft. One broken light is probably just a light bulb, but 3 broken lights and inop pitot heat may be a more serious electrical problem. If you don't know the state of the aircraft then you can't make informed decisions.&lt;/li&gt;&#xA;&lt;li&gt;Plans change. You might set off for a day VFR flight on a clear, sunny day intending to be home hours before sunset. But if the weather changes quickly or you get delayed then your flight home might have to be night VFR or IFR. If you have equipment issues that restrict your options then it would be best to know that before you depart.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's nothing wrong with flying with inop equipment provided that you know about it, you've complied with the rules in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1213&quot; rel=&quot;nofollow&quot;&gt;91.213&lt;/a&gt; on minimum required equipment and deactivating and placarding, and you've made a conscious assessment of the risk. But not inspecting the aircraft properly or deliberately ignoring inop equipment is a really great way to put yourself in an &quot;up there wishing you were down here&quot; situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And from a regulatory point of view, if you don't preflight properly then you're probably in violation of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1103&quot; rel=&quot;nofollow&quot;&gt;91.103&lt;/a&gt; (&quot;become familiar with all available information concerning that flight&quot;) and of course &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow&quot;&gt;91.13&lt;/a&gt; (&quot;No person may operate an aircraft in a careless or reckless manner&quot;).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2015-12-15T17:51:29.170" LastActivityDate="2015-12-15T17:51:29.170" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23683" PostTypeId="2" ParentId="23681" CreationDate="2015-12-15T13:54:43.317" Score="7" Body="&lt;p&gt;Departure means that the aircraft has departed from controlled flight. From &lt;a href=&quot;http://www.faa.gov/news/updates/?newsId=83285&amp;amp;omniRss=news_updatesAoc&amp;amp;cid=101_N_U&quot;&gt;FAA news&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A Loss of Control (LOC) accident involves an unintended departure of an aircraft from controlled flight&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this &lt;a href=&quot;https://www.youtube.com/watch?v=Rv9YC-gaNYo&quot;&gt;video about flight testing F-16s&lt;/a&gt;, the test pilot says 'intentionally departed from controlled flight' and later 'the aircraft is prone to departure if mishandled' and 'the aircraft departed in yaw'.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-15T14:09:00.797" LastActivityDate="2015-12-15T14:09:00.797" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23684" PostTypeId="2" ParentId="23676" CreationDate="2015-12-15T14:16:06.973" Score="3" Body="&lt;p&gt;If the canard has a thinner leading edge compared to the stabilizer, this &lt;em&gt;could&lt;/em&gt; happen. From &lt;a href=&quot;https://www.regional-services.com/Files/Pdf/pwk_0161-Think-Ice.pdf&quot; rel=&quot;nofollow&quot;&gt;BEA Systems Think Ice&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A relatively large radius aerofoil at moderate or low airspeed creates a larger pressure wave ahead of the leading edge, which forces the air around it,&#xA;  carrying most of the moisture with it. Only droplets sufficiently heavy to overcome this flow will impact on the leading edge. Thus, a large chord aerofoil with a blunt leading edge has low ice accretion efficiency.  Conversely, a narrow radius leading edge generates a smaller pressure wave and so the accretion rate is greater. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that by the same token, the stabilizer is more prone to icing compared to the main wing.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-15T14:16:06.973" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23686" PostTypeId="2" ParentId="23676" CreationDate="2015-12-15T15:40:39.050" Score="16" Body="&lt;p&gt;It has to do with the local speed around the airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a canard configuration, the forward wing has to produce more lift per area than the main wing in order to have &lt;a href=&quot;https://aviation.stackexchange.com/questions/12507/what-does-it-mean-for-a-plane-to-be-aerodynamically-stable/12511?s=1%7C0.1685#12511&quot;&gt;natural longitudinal (or pitch) stability&lt;/a&gt;. This means the suction is more intense, and the pressure on the upper side of the airfoil right behind the leading edge is lower than on the main wing. Also, the angle of attack of the wing is higher, presenting a larger area to the oncoming flow. Large droplets of supercooled water will simply splash on the leading edge and freeze there instantly, causing clear icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a conventional aircraft the tail surface will provide very little lift, and in many cases even produces a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21499/what-causes-tail-down-force/21567?s=1%7C0.1988#21567&quot;&gt;small downforce&lt;/a&gt;. Now the main wing shows lower pressure on the forward part of the airfoil, just where ice collects the most. In the special case where the tailplane is in the wake of the wing, some of the water droplets will have frozen to the wing already and less water will be available to cause tailplane icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The capacity of air to hold water depends not only on temperature, but also on pressure: The lower the pressure, &lt;a href=&quot;https://aviation.stackexchange.com/questions/14327/what-is-the-mechanism-by-which-condensation-forms-above-wings/14331?s=1%7C0.2183#14331&quot;&gt;the more likely it is for condensation to happen&lt;/a&gt;. Condensed, super-cooled water, or liquid water hitting a cool surface, will form ice. Now you have both components needed for the explanation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitch stability is the explanation for the higher propensity of canard wings to collect ice than conventional tailplanes!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-10-13T07:02:16.803" LastActivityDate="2017-10-13T07:02:16.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23687" PostTypeId="2" ParentId="23675" CreationDate="2015-12-15T15:57:26.967" Score="6" Body="&lt;p&gt;The biggest airplanes first used water for taking off and landing, and only later were similarly sized land airplanes built. Bigger airplanes tend to have a higher wing loading and so require longer runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Caproni_Ca.60&quot; rel=&quot;noreferrer&quot;&gt;Caproni Ca.60&lt;/a&gt; was the biggest aircraft of its time (1921) and is still bigger than a Jumbo Jet if you use wing area to measure size. It could only be built as a flying boat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QfyNW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QfyNW.jpg&quot; alt=&quot;Caproni Ca.60&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Caproni Ca.60 (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Caproni_Ca.60#/media/File:CaproniCa.60.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another biggest aircraft of its time was the Dornier Do-X from 1929. On one occasion it carried 169 people into the air, including one stowaway. Its regular capacity of 60 to 100 passengers would only be surpassed in the jet age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tvPW7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tvPW7.jpg&quot; alt=&quot;Dornier Do-X&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dornier Do-X in flight (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/e/e3/Bundesarchiv_Bild_102-12963%2C_Flugboot_%22Do_X%22.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). This one actually flew, but was hampered by the small aircraft engines which were available at its time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying boats were also used on the first transatlantic and transpacific routes, and to connect the parts of the British Empire by air, &lt;a href=&quot;https://en.wikipedia.org/wiki/Imperial_Airways&quot; rel=&quot;noreferrer&quot;&gt;Imperial Airways&lt;/a&gt; used a fleet of floatplanes and &lt;a href=&quot;https://en.wikipedia.org/wiki/Imperial_Airways#Short_Empire_Flying_Boats&quot; rel=&quot;noreferrer&quot;&gt;flying boats&lt;/a&gt;. Routes were strung along lakes as staging points.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cxIrb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cxIrb.jpg&quot; alt=&quot;Short Empire in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short Empire as operated by Imperial Airways (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Short_Empire#/media/File:VH-ABBcrop.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long runways were only built during the second World War when the weight and speed advantage of land airplanes made them the preferred choice for bombers. With the runways in place, flying boats soon disappeared.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-15T21:08:10.937" LastActivityDate="2015-12-15T21:08:10.937" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23688" PostTypeId="1" CreationDate="2015-12-15T16:30:35.350" Score="7" ViewCount="1320" Body="&lt;p&gt;Is there any FAA or EASA regulation that dictates the use of locking electrical connectors for certain systems on an aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Self-locking (ratchet mechanism, bayonet) and positive locking (wire locked) connectors are used on most systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there are also push-pull connectors mainly used on headsets or quick disconnect batteries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a regulation that prohibits the use of not self-locking or positive locked electrical connectors for certain systems even though they fulfill exactly the same mechaninal specifications concerning vibration, shock and durability?&lt;/p&gt;&#xA;" OwnerUserId="8312" LastEditorUserId="19" LastEditDate="2017-01-16T16:00:54.947" LastActivityDate="2017-01-16T16:00:54.947" Title="Is there a requirement for self-locking / positive locking electrical connectors for aircraft systems?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23689" PostTypeId="1" AcceptedAnswerId="23696" CreationDate="2015-12-15T17:59:25.923" Score="14" ViewCount="5281" Body="&lt;p&gt;I've been reading my private pilot books for when I start in February and Carb Heat has me stuck in a rut. I feel like I need to have a very solid understanding of this being that I live in a very humid area. The book says do not use carb heat on the ground and on taxi because it will draw unfiltered air into the engine(air from exhaust)... But what is the difference between using it in the air vs on the ground and isn't the risk of icing just as equal in the air as on the ground?&lt;/p&gt;&#xA;" OwnerUserId="12677" LastEditorUserId="167" LastEditDate="2015-12-16T04:31:07.543" LastActivityDate="2017-08-26T20:30:27.957" Title="Why is carburetor heat use discouraged on the ground?" Tags="&lt;aircraft-systems&gt;&lt;piston-engine&gt;&lt;icing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23690" PostTypeId="2" ParentId="23689" CreationDate="2015-12-15T18:17:17.800" Score="7" Body="&lt;p&gt;Several possible reasons.  While taxiing an engine failure is not as critical.  While in flight an aircraft is much less likely to ingest dirt, rocks, twigs, grass etc.  Finally, while at flying speed, the exhaust gases are carried &quot;behind&quot; the aircraft, while at slow taxi speed, there is less airflow to do that.  &lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2015-12-15T18:17:17.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23691" PostTypeId="1" AcceptedAnswerId="23692" CreationDate="2015-12-15T18:35:29.040" Score="6" ViewCount="1319" Body="&lt;p&gt;I saw the following 2012 photo of a light ground attack jet used by the Syrian regime in an attack on Tel Rafat:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lcyex.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lcyex.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not recognize the type, however, and it does not appear to be any of the regular ex-Soviet types normally flown by the Syrian air force (MiG-29, MiG-25, MiG-23, MiG-21, Su-24, Su-22). Does anybody know what it is?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="19" LastEditDate="2016-07-08T11:22:38.550" LastActivityDate="2016-07-08T11:22:38.550" Title="What type is this Syrian light attack aircraft?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23692" PostTypeId="2" ParentId="23691" CreationDate="2015-12-15T18:41:59.490" Score="14" Body="&lt;p&gt;Its a Syrian Aero L-39 Albatros.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the same image (just a bit sooner on the second missle lauch) when searching Google for &lt;a href=&quot;https://www.google.com/search?q=l-39&amp;amp;safe=off&amp;amp;espv=2&amp;amp;biw=1637&amp;amp;bih=894&amp;amp;source=lnms&amp;amp;tbm=isch&amp;amp;sa=X&amp;amp;ved=0ahUKEwjQxOeewt7JAhWKSSYKHfnpD_cQ_AUIBigB#safe=off&amp;amp;tbm=isch&amp;amp;q=syrian+l-39&quot;&gt;Syrian L-39&lt;/a&gt; (second result). &lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2015-12-15T18:41:59.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23693" PostTypeId="2" ParentId="23681" CreationDate="2015-12-15T19:02:22.490" Score="6" Body="&lt;p&gt;Expanding on the other answer...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A loss of controlled flight (departure) is what happens when the aircraft is moving in an uncontrolled manner (on any one or all axis). For example &lt;a href=&quot;https://www.youtube.com/watch?v=Rv9YC-gaNYo&quot;&gt;in the video&lt;/a&gt; that the other answer linked, the departure from controlled flight happens when the aircraft exceeds its operating envelope and begins uncommanded movement in any axis, in this case when the pilot yanks back on the stick and the aircraft yaws uncommanded (like a &quot;boot full of rudder&quot; as the person in the video comments).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why an aircraft can depart controlled flight in individual axis while retaining control in others. You can intentionally make an aircraft depart controlled flight (spin for example) and if the control surfaces still have enough authority, it can be recovered (altitude withstanding). You aren't really &quot;in control&quot; but you are coaxing the aircraft back into the flight envelope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you don't have enough control authority to get back into the flight envelope, or altitude, this is otherwise known as a crash... Some aircraft cannot be recovered from maneuvers like spins (Cirrus SR-20/22 for example, not certified to at least).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, controlled flight is defined as providing control inputs without uncommanded movement on any axis (significant, for example just using ailerons may result in yaw). Any departure from controlled flight is uncontrolled flight, even if you regain control later.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2015-12-15T19:02:22.490" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23694" PostTypeId="1" AcceptedAnswerId="23695" CreationDate="2015-12-15T19:05:54.097" Score="11" ViewCount="1480" Body="&lt;p&gt;The last night I had an &quot;interesting&quot; experience with an aborted landing, which was a bit dramatic for my liking. Heavy fog and darkness didn't help either. Pilot told us that the reason for aborted landing is a problem with navigation instruments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today I checked the flightradar24 data, which I've attached for your pleasure, but it didn't ease my worries since according to site's data the first attempt missed the runway completely.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;How accurate are these flightradar's data?&lt;/li&gt;&#xA;&lt;li&gt;How common is for pilot to miss runway in heavy fog?&lt;/li&gt;&#xA;&lt;li&gt;Is there a reason to be worried while flying 50 feet above meadows in heavy fog? Possibly with malfunctioning navigation equipment? &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ONX8O.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ONX8O.png&quot; alt=&quot;flightradar24 data&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12678" LastEditorUserId="12678" LastEditDate="2015-12-15T19:51:10.010" LastActivityDate="2015-12-15T22:16:23.793" Title="Is there a reason to be worried about go-arounds as a passenger?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;passenger&gt;&lt;go-around&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ClosedDate="2015-12-15T22:27:11.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="23695" PostTypeId="2" ParentId="23694" CreationDate="2015-12-15T19:16:23.610" Score="14" Body="&lt;p&gt;A go-around is nothing to be worried about as a passenger.  What would be worrying is if the pilots elected not to go around when conditions warranted it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dark likely isn't an issue with this go around as approach lighting systems can become exceptionally bright when requested (to the point you'll need sunglasses to look at them if visibility is good).  What was likely a factor was fog.  Airplanes need a minimum amount of visibility to land and if conditions are marginal you won't really know until you fly the approach and either see the lights and land or do not see the lights and go around.  For normal ILS approaches you would initiate this go around at 200 ft above the airport elevation.  For very low visibility approaches this decision height may be 100 feet or less above the airport elevation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point at which you go around if you fail to see the runway environment is well defined and procedures ensure obstacle clearance so there is no danger as long as procedures are flown as published.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility for the go around could be the airplane in front of you failed to clear the runway speedily due to low visibility.  If the preceding aircraft was still occupying the runway then your airplane would have to go around.  There are a few other issues that could warrant missed approaches (e.g. windshear) but in all of these cases the go around is the safer option than proceeding with the landing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your pilots made the safe decision to go around and this is what you should take from the experience.  There is zero reason to be worried.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To address your added specific questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Flightradar24 flight track data is unreliable.  It is neither true radar positioning or necessarily true GPS positioning.  It is nice for zoomed out flight tracks but is not reliably suitable for the precision during landing/takeoff.  Do not use it as a basis for worrying that your approach was not properly aligned.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Extremely rarely if you mean not being aligned with the runway.  Uncommon if you just mean not seeing the approach lights but otherwise on course to land.  The navigation signals used in ILS approaches are broadcast down the runway centerline for the lateral guidance and from just next to the runway approximately 1000 feet past the beginning of the runway aimed 3 degrees up for the vertical guidance.  These signals are only usable in a cone that radiated outward from the runway.  Furthermore the navigation accuracy of the ILS receivers are regularly tested on the airplane.  Combined with monitoring by air traffic controllers you will not end up on a parallel course that does not intersect the runway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The vertical data is also not reliable.  Your airplane approached on the glideslope and if it made it down to 50 feet this would have been just over the very beginning of the runway.  After initiating the go around it would climb (likely to between 2000 and 3000 feet) and attempt another ILS approach.  At no time is the airplane lingering at 50 feet above the ground anywhere but over the runway for a very short period of time.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The video below is an example of a very low visibility approach and you can see an example of how low the airplane can get before visual contact is made with the approach lights and runway.  At predetermined points based on the aircraft, airport and crew qualifications the airplane would initiate a go around if these things were not seen.  For standard ILS approaches this would be when the airplane announces &quot;200 feet&quot;.  For category II ILS approaches, it would be at &quot;100 feet&quot;.  In the video below a category III approach is shown which has an even lower altitude to initiate a missed approach.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/UV_vWtAJIow?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-12-15T20:37:50.713" LastActivityDate="2015-12-15T20:37:50.713" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23696" PostTypeId="2" ParentId="23689" CreationDate="2015-12-15T19:31:16.393" Score="11" Body="&lt;p&gt;If you feel that you would need carb heat sitting on the ground, I'd recommend taxing back and waiting for conditions to improve. If you are set on going, usually doing a run-up at the runway before take-off will tell you if you have carb ice or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other answer gave good reasons, sucking in some FOD (foreign object debris), but there are some other things you would want to consider...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Forgetting to push the carb heat back in before takeoff&lt;/strong&gt;&#xA;&lt;br&gt; - Especially important when taking off from short fields, you want all the power your engine has to offer, as carb heat robs your engine of some power. If you have carb ice, applying carb heat will cause your engine to make even less power (hot air is less dense than cold air). 3/4 of the way down a 1200 foot runway is a bad time to realize the carb heat is still on, because it probably isn't on your takeoff checklist.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Carb heat is not very effective on a cold engine&lt;/strong&gt;&#xA;&lt;br&gt; - This is a real problem when you are at idle or especially gliding, the airflow over the engine components and the exhaust just doesn't create enough heat to melt the ice in the carb (at least not very quickly). This is why you may be instructed to &quot;clear&quot; the engine periodically during low power operations. This involves adding power and then carb heat to help melt any ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That all being said, its not so much a rule as a recommendation. You'll probably find that during your flight training you'll end up leaving the carb heat on while on the ground for short periods. This happens a lot during landing operations when you are instructed to have carb heat on (my instructor taught me mid-field downwind, &quot;Seat Belts, Gear, Fuel Selector, &lt;em&gt;Carb Heat&lt;/em&gt;, Mixture, Prop, Power&quot;). You'll end up leaving it on until you've cleared the runway (or set up for a touch-and-go) and are running your &quot;after landing&quot; checklists.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="3825" LastEditDate="2015-12-15T23:40:40.863" LastActivityDate="2015-12-15T23:40:40.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23697" PostTypeId="2" ParentId="23694" CreationDate="2015-12-15T20:21:56.840" Score="4" Body="&lt;ol&gt;&#xA;&lt;li&gt;How accurate are these flightradar's data?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Flightradar24 relies often on ADS-B transmissions from the aircraft. Depending on the aircraft the accuracy of the transmitted ADS-B position  varies from very accurate to not accurate at all. This particular A319 belongs in the latter category; the source of the data was the &lt;a href=&quot;https://aviation.stackexchange.com/q/2275/19&quot;&gt;Inertial Navigation System&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;How common is for pilot to miss runway in heavy fog?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Quite common. Depending on the aircraft, the flight crew and airport navigation facilities the aircraft can land in zero visibility. Nikola Tesla airport has &lt;a href=&quot;https://aviation.stackexchange.com/q/2620/19&quot;&gt;Instrument Landing System&lt;/a&gt; (ILS) CAT IIIb on runway 12 (where you landed) which means that the navigation equipment can support autolanding. In this case the decision height can be at the runway, the minimum visibility at the runway is 50 meters. At the moment there is no Notice to Airmen (NOTAM) published regarding maintenance of the system so I assume it is operable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know whether this particular aircraft and its crew are approved for ILS CAT IIIb operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If either the airport, the aircraft or the flight crew cannot support autoland, then the runway has to be visible at a predefined height. If the runway is not in sight at this height the flight crew will follow the missed approach procedure.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;Is there a reason to be worried while flying 50 feet above meadows in heavy fog? Possibly with malfunctioning navigation&#xA;equipment?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;No there is no reason to worry. This is normal operation, it happens everyday somewhere in the world. The aircraft is guided by two independent guidance systems that cross check each other. If there is a discrepancy between the two, an alarm sounds and the approach is aborted. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navigation system on the ground is carefully monitored, if anything malfunctions the system will raise an alarm. The area around the runway and especially around the antennae of the navigation system is kept clear of obstructions when the airport is under Low Visibility Procedures (LVP) &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-12-15T22:16:23.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23698" PostTypeId="2" ParentId="23527" CreationDate="2015-12-15T21:58:50.537" Score="0" Body="&lt;p&gt;In case of any hesitations you should refer to the documentation of your propeller manufacturer. They contain criteria for defects, which ones can be ignored, which ones can be fixed by the aircraft owner, and which ones must be fixed by the manufacturer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any other action (or inaction) may cause damage to the prop, engine, and consequentially to the aircraft (be it from a crash land, or a glide land). &lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2015-12-15T21:58:50.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23699" PostTypeId="2" ParentId="22180" CreationDate="2015-12-15T23:48:55.703" Score="2" Body="&lt;p&gt;To answer your first question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The manufacturer (OEM) usually publishes an estimate of maintenance man-hours (MH) needed for each task within their Maintenance Planning Document (MPD). For non-MPD tasks, source documents such as Service Bulletins usually also have an estimate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an A- or C-Check work package is created, the OEM's estimates for each task can simply be added up to get a rough idea of the total number of MH needed. HOWEVER: this is just an estimate! The OEM's figures assume that the work is being carried out in ideal conditions, i.e. the tools are all at hand; paperwork is printed out; access to the aircraft is readily available; and the mechanic is well versed in doing that task. The OEM's estimate therefore needs to be adjusted. I've seen various organizations use factors varying between 2 to 4 i.e. if the OEM says one hour, you plan for between two to four hours. The factor will typically vary depending on factors such as:&#xA;- facilities / equipment available at the maintenance location;&#xA;- experience and skill levels of the technicians;&#xA;- age and condition of the aircraft;&#xA;- and even the type of check (e.g. A-Check vs C-Check).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the total MH for the A- or C-Check package is calculated, you can get a rough estimate of the ground-time you'll need for the check, based on the manpower you have available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HOWEVER, a word of caution! As Peter says, this is not an exact science! Remember that the number of MH is different from the actual time it takes to do the task (known as &quot;elapsed time&quot;)... E.g. time for a sealant to cure doesn't count towards the MH, but does still need time in the real world. Remember, just because a woman can deliver a baby in nine months, doesn't mean nine women can deliver a baby in one month!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, the company should have a process in place to gather and analyze data on planned MH vs utilized MH and planned vs utilized ground-time and incorporate this into their production planning activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your second question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen above, there is no &quot;exact formulation&quot;. The calculations based on the OEM's MPD and source documents provide a ballpark figure, to which you then need to apply your engineering judgement and experience. This is where data gathering and analyses can be invaluable to an organization's planning process.&lt;/p&gt;&#xA;" OwnerUserId="12666" LastActivityDate="2015-12-15T23:48:55.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23700" PostTypeId="1" AcceptedAnswerId="23705" CreationDate="2015-12-16T02:32:54.177" Score="11" ViewCount="549" Body="&lt;p&gt;Why can't we just extend linear supersonic theory beyond M = 5? I've looked at NASA papers discussing everything from geometric effects, air disassociation, and thermal coupling, but no clear and concise explanation as to why we can't just extend linear airfoil theory beyond M = 5.&lt;/p&gt;&#xA;" OwnerUserId="4432" LastActivityDate="2015-12-16T19:47:12.993" Title="Why does linear airfoil theory break down at hypersonic speeds?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;airfoil&gt;&lt;hypersonic&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23701" PostTypeId="1" CreationDate="2015-12-16T05:04:32.643" Score="18" ViewCount="23588" Body="&lt;p&gt;I've lived for years about eight miles NW of Boston's Logan Airport. Although I can't say we get a lot of aircraft noise, once in a while, due to winds or air traffic, there will be a long line of planes traveling right over my house, perhaps 6000-8000 feet up, descending into Logan. At night you can sometimes see three in a row, with a fourth one turning on its landing lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the time the overhead planes sound mostly like a roar with some jet whine. However, once in a while a plane will suddenly start making a very strange sound like an enormous blown Coke bottle. Often the pitch will descend during a half dozen seconds, stay constant for a dozen seconds, and then rise again until the sound disappears.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My best guess is that the sound is caused by the pilot lowering the wheels during their descent, and that it only happens on certain models of aircraft. As the wheel well covers open, the air blowing across the wells sounds like that giant Coke bottle, with the pitch decreasing as the opening increases. On certain models, the covers will then close once the wheels are down, causing the pitch to go back up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;strong&gt;Edit:&lt;/strong&gt; it's been pointed out that gear isn't dropped until 2000-3000 feet, so in my case that isn't the sound. So, I've removed all those videos, cool though they may be.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is my guess right? What model/manufacturer of large jet would make this sound?&lt;/p&gt;&#xA;" OwnerUserId="9825" LastEditorUserId="19" LastEditDate="2016-07-08T11:22:10.767" LastActivityDate="2018-06-18T07:04:03.973" Title="What causes descending aircraft to make a noise like a giant blown bottle?" Tags="&lt;noise&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23704" PostTypeId="2" ParentId="2570" CreationDate="2015-12-16T11:41:23.020" Score="13" Body="&lt;p&gt;A light aircraft (e.g. C172) has a landing roll of around 500 feet. There are no 50 foot obstacles to consider so the 1500 foot to a 50 foot obstacle isn't required. Thats from 60 knots to a full stop. Going from 60 knots to 30 knots (30 knots is the wind over the deck) means it will be less than half that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the problem is not one of the aircraft, most light aircraft with similar performance are perfectly capable of doing it without a landing hook or anything like that. The problem is the pilot, with no training or practice this will be very hard to do because the deck is moving in the swell, and its also moving sideways due to the angled deck. A bad crash is the most likely outcome. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An ex navy pilot with recent experience. Now thats a different story, even without arrestor hook etc etc they would find it easy compared to landing their big heavy jet on the deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Corvalis is a hot ship in light aircraft terms with a much longer ground roll, so this would be tight. Again with skill (ex navy pilot etc etc) and wind over the deck (you can get going on 30 knots from the ship even if the wind is calm) I think it could still be done.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastEditorUserId="9679" LastEditDate="2015-12-16T16:36:26.170" LastActivityDate="2015-12-16T16:36:26.170" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23705" PostTypeId="2" ParentId="23700" CreationDate="2015-12-16T12:11:34.893" Score="9" Body="&lt;p&gt;The linear theory makes certain assumptions in its formulation:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The flow is irrotational and isentropic.&lt;/li&gt;&#xA;&lt;li&gt;The perturbations are small; i.e. the bodies are small at small angles of attack.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, hypersonic flow &lt;a href=&quot;http://nptel.ac.in/courses/101103004/module4/lec6/2.html&quot; rel=&quot;noreferrer&quot;&gt;violates these assumptions&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For a body in hypersonic flow (blunt body with detached bow shock), an entropy gradient is developed that varies along the distance of the body. It results in an entropy layer that persists all along the body.&lt;/li&gt;&#xA;&lt;li&gt;In a hypersonic flow, the viscous boundary layer interacts with the shock and entropy layer and the kinetic energy of the flow is dissipated by the effect of friction within the boundary layer. Due to these viscous effects, the flow is no longer irrotational.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that the linear theory is not applicable if the flow is considered hypersonic. M &gt; 5 is usually taken as hypersonic. Linear theory is not applicable in transonic regime either.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="4474" LastEditDate="2015-12-16T19:47:12.993" LastActivityDate="2015-12-16T19:47:12.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23708" PostTypeId="2" ParentId="23654" CreationDate="2015-12-16T13:47:45.233" Score="4" Body="&lt;p&gt;Some&lt;em&gt;thing&lt;/em&gt; — yes, albeit not intentionally in this case: There was an accident in Sweden some years ago, in which a Gripen pilot was blown out of his aircraft because his legs and flight suit, affected by some high-G turns, actioned the ejection handle.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://en.wikipedia.org/wiki/Accidents_and_incidents_involving_the_JAS_39_Gripen#April_2007&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; and the &lt;a href=&quot;http://www.havkom.se/assets/reports/Swedish/rm2008_01.pdf&quot; rel=&quot;nofollow&quot;&gt;Official report&lt;/a&gt; from the Accident Investigation Authority (PDF in Swedish).&lt;/p&gt;&#xA;" OwnerUserId="12693" LastEditorUserId="1467" LastEditDate="2015-12-16T13:57:48.260" LastActivityDate="2015-12-16T13:57:48.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23709" PostTypeId="1" AcceptedAnswerId="23710" CreationDate="2015-12-16T15:09:47.890" Score="6" ViewCount="7274" Body="&lt;p&gt;The first paragraph of the FAA PHAK Chapter 14 - Airspace says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two categories of airspace are: regulatory and&#xA;  nonregulatory. Within these two categories there are four&#xA;  types: controlled, uncontrolled, special use, and other&#xA;  airspace. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It never says anything further about regulatory and nonregulatory. So what do these terms mean and what are their differences?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="11402" LastEditDate="2015-12-16T15:28:00.110" LastActivityDate="2015-12-16T16:52:13.847" Title="What is the difference between regulatory and nonregulatory airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23710" PostTypeId="2" ParentId="23709" CreationDate="2015-12-16T15:54:51.877" Score="6" Body="&lt;p&gt;Non-regulatory airspace is &lt;a href=&quot;https://en.wikipedia.org/wiki/Military_operations_area&quot;&gt;MOAs&lt;/a&gt;, &lt;a href=&quot;http://www.cfinotebook.net/notebook/national-airspace-system/warning-area.php&quot;&gt;Warning Areas&lt;/a&gt;, Alert Areas, and Controlled Firing Areas &lt;a href=&quot;http://ierwtraining.com/Airspace/index.html&quot;&gt;(source 1)&lt;/a&gt;, &lt;a href=&quot;http://www.cfinotebook.net/notebook/national-airspace-system/military-operating-area.php&quot;&gt;(source 2)&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other information should be located in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;AIM&lt;/a&gt; Ch 3-4, Special Use Airspace. Specifically 3-4-1(c)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically non-regulatory areas mean that the FAA does not make regulatory enforcement in those areas due to special (military) operations. Usually the non-enforcement is only for participating aircraft, and generally recreational/commercial aircraft would not fall under any non-regulatory rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in an active MOA with aircraft practicing low-altitude speed runs, the FAA would not enforce the 250 knot speed limit on participating aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is in the AIM, Ch 3 Section 4, Part 5(b) &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Military pilots flying in an active MOA are exampted from the provisions of 14 CFR Section 91.303(c) and (d) which prohibits aerobatic flight within Class D and E surface areas and within Federal Airways. Additionally the Department of Defense has been issued an authorization to operate aircraft at indicated airspeeds in excess of 250 knots below 10,000 feet MSL within active MOAs..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For another example, consider warning areas, which are areas extending 3 miles from the coast. Since this area may include international waters (think of the area between Alaska and Russia), the FAA can't really regulate operations in all these areas. The US Navy also controls some of these areas and &quot;shares&quot; jurisdiction with the FAA.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-16T16:24:07.707" LastActivityDate="2015-12-16T16:24:07.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23711" PostTypeId="2" ParentId="23709" CreationDate="2015-12-16T16:52:13.847" Score="5" Body="&lt;p&gt;In the US, the airspace is categorized into regulatory and non-regulatory. According to &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot;&gt;FAA AIM&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Regulatory airspace includes Restricted, Prohibited and various classes (Class A, B, C, D, and E) airspace- These are the areas where FAA regulations are in place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Nonregulatory airspace includes MOAs (military operations area), warning areas, alert areas, and controlled firing areas.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The non-regulatory airspace are the regions in airspace where the FAA cannot enforce regulations &lt;a href=&quot;https://www.faa.gov/air_traffic/nas/nynjphl_redesign/documentation/feis/media/Appendix_A-National_Airspace_System_Overview.pdf&quot;&gt;due to various reasons&lt;/a&gt; (legal and practical).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the FAA cannot legally restrict aircraft as it lies outside of U.S. airspace. In case of MOA, VFR aircraft are not restricted, though they are encouraged to remain outside.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-16T16:52:13.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23717" PostTypeId="1" CreationDate="2015-12-16T21:43:07.023" Score="4" ViewCount="3600" Body="&lt;p&gt;I recently obtained my CPL at FTA.&lt;/p&gt;&#xA;&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/8926/1696&quot;&gt;one of the answers&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The normal progression is this - you can technically get a flying job after 150-200 hours of private training and flying, having achieved your commercial pilot licence (CPL). I say 'technically' because if you only have minimum hours and minimum qualifications you have to look very hard for a job. Most people straight away get an instructor rating, so they can get a job teaching people to fly. Other early jobs include sightseeing flights, parachute flights, and mail flights to remote towns.&lt;/p&gt;&#xA;&lt;p&gt;Your training will have been in light aircraft, but fortunately Australia has possibly the largest light aircraft industry in the world, so there's lots of jobs in these planes. It's highly unlikely that your first job will be in anything bigger than a 6 seater plane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Could somebody suggest based on your experience, light aircraft operators willing to hire a 250 hours pilot?&lt;/p&gt;&#xA;&lt;p&gt;I already sent my resume to a list of GA operators and did not receive any reply. I need some advice on the best approach when trying to get my first job.&#xA;Look forward to hearing from you.&lt;/p&gt;&#xA;" OwnerUserId="12697" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-18T21:34:28.477" Title="What general aviation operators might hire a low time pilot?" Tags="&lt;pilots&gt;&lt;career&gt;&lt;australia&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23718" PostTypeId="2" ParentId="23717" CreationDate="2015-12-16T23:12:21.840" Score="4" Body="&lt;p&gt;Getting your instructor certificate is your best bet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, there are jobs out there for traffic watch, banner towing, and flying jump planes for skydivers.  Also glider towing and sightseeing.  Ferry flying is possible, although I'd be careful of any place that would hire you with very few hours -- they may be cutting corners &amp;amp; guys with more time look at the operation &amp;amp; say &quot;no thanks.&quot;  Not necessarily, but be cautious with anything that looks &quot;too good to be true.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these are typically positions that only have a few, or one, or no openings at a time, and those spots are in pretty high demand.  So persistence and personal contact (not just sending a resume) are probably vital to landing one of these jobs.  The place where you're most likely to have more options is flight instructing; obviously that requires the CFI certificate (or equivalent for outside the US).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-16T23:12:21.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23719" PostTypeId="2" ParentId="12986" CreationDate="2015-12-16T23:14:35.917" Score="1" Body="&lt;p&gt;Commercial operations do not normally do anything special to prepare for a pilot becoming sick. If a pilot has any kind of impairing health issue, then they are not supposed to fly at all. One of the purposes of the co-pilot is to be a backup for the pilot in case the pilot has a problem, like being incapacitated due to illness. In some cases small aircraft have crashed because they had only a single pilot who became incapacitated, but this does not happen to commercial flights because they invariably have two pilots on board. Even cargo flights have two pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If both pilots were to become incapacitated, and the flight crew noticed, they would first have to get access to the flight deck and the purser has a code to do that. Then, in all likelihood, they would ask in the cabin if there were any pilots present. They do not know who might be a pilot or not, so they would have to ask. They will need to do this because to simply operate the radios requires knowledge and skill. For example, to talk you have to press a button. If you don't know where that button is located (there are hundreds of buttons in a cockpit), then you cannot talk, even if the radio is on the right frequency. RedGrittyBrick's idea that a steward would operate the aircraft or &quot;help out&quot; or that stewards are trained to operate an aircraft in an emergency is not correct.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2015-12-16T23:14:35.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23720" PostTypeId="1" CreationDate="2015-12-16T23:59:43.030" Score="3" ViewCount="705" Body="&lt;p&gt;Why does the canard rotor wing (CRW) use a canard?  The CRW is a helicopter using engine exhaust to drive the rotor.  The exhaust can be used in the normal way to drive the aircraft once high enough speed has been reached.  Why can't the CRW use a tail instead?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-12-17T00:20:29.667" Title="Why does the Canard Rotor Wing use a Canard?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23721" PostTypeId="2" ParentId="23720" CreationDate="2015-12-17T00:20:29.667" Score="4" Body="&lt;p&gt;The Canard rotor/wing demonstrator, later called the X-50 Dragonfly was a Stop-Rotor Rotary Wing Aircraft made by Boeing and DARPA to demonstrate the principle that a helicopter's rotor could be stopped in flight and act as a fixed wing (like in movie The Sixth Day).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d9zIT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d9zIT.jpg&quot; alt=&quot;X-50&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from boeing.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The canard is used in case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-50_Dragonfly&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing X-50 Dragonfly&lt;/a&gt; in order to overcome the transient aerodynamic loads that occurred during conversion from rotary to fixed-wing flight. During transition from rotary mode to fixed wing mode, the rotor is being unloaded and the aircraft has to produce enough lift. The designers used both a canard and horizontal stabilizer to overcome this problem. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://people.nas.nasa.gov/~aftosmis/publications/aiaa2001-0997.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Canard Rotor/Wing Aircraft&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During development, analysis and testing indicated that the X-wing design encountered high transient aerodynamic loads during the conversion from rotary to fixed-wing flight. The CRW design addresses this issue by generating positive lift on both the canard and horizontal tail during conversion. By deploying the flapped canard and the full-flying horizontal tail, enough lift can be produced to support the weight of the aircraft, and the main rotor can be completely unloaded throughout the conversion maneuver.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aircraft never made a conversion flight and the program was canceled.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-17T00:20:29.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23722" PostTypeId="1" AcceptedAnswerId="23723" CreationDate="2015-12-17T00:23:39.987" Score="9" ViewCount="475" Body="&lt;p&gt;I was reading something at work that said the company has installed an Enhanced Vision System on the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FedEx Express added Enhanced Vision Systems to 250 aircraft, which will greatly improve pilots’ ability to land in low visibility conditions and mitigate potential weather delays. The company is the only U.S. carrier with FAA approval to use the technology as low as 100 feet on instrument approaches.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is this system and how does it work? Is it some type of FLIR?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2015-12-17T00:40:13.767" LastActivityDate="2015-12-17T01:03:31.597" Title="What is an Enhanced Vision System?" Tags="&lt;landing&gt;&lt;avionics&gt;&lt;visibility&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23723" PostTypeId="2" ParentId="23722" CreationDate="2015-12-17T00:46:14.347" Score="9" Body="&lt;p&gt;It's essentially a combination of the capabilities of &lt;a href=&quot;https://en.wikipedia.org/wiki/Forward_looking_infrared&quot;&gt;FLIR&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Night_vision_device&quot;&gt;NVG's&lt;/a&gt;, although built into the aircraft and displayed in the HUD rather than worn as goggles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FLIR, short for Forward Looking Infra Red, uses far-IR to see the heat of terrain, and essentially turns the night into day, at least for the field of view that it &quot;sees.&quot;  NVG's (Night Vision Goggles) use near-IR and magnified visible light.  The near-IR doesn't see terrain except to the extent that it's illuminated by something (moonlight, starlight), and far-IR can't do much to tell the difference between a light that's on or off (so you can see the runway edge, but you can't see the runway edge lights using FLIR, for instance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two systems have slightly differing capabilities and limitations; when both are fused together onto a display (i.e. a Heads-Up Display, or HUD), the pilot gets a pretty amazing picture of what is directly in front of him: the far IR shows him the runway edges, taxiways, pavement, buildings, obstructions,etc, and the near-IR makes lights (i.e. runway and taxiway lights) stand out.  In low visibility, the far-IR tends to be somewhat more degraded than the near-IR, whereas at night &amp;amp; with no moon, the near-IR shows the lights but not much else.  Together, the pilot can get the runway lights in sight sooner than he could unaided, and by the time he's landing he can see &quot;everything&quot; in the field of view of the HUD, not just the lights themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example videos:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=DR9lyAM2YNE&quot;&gt;YouTube&lt;/a&gt; &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.elbitsystems-us.com/commercial-aviation/products/enhanced-flight-vision-system-evs/efvs-action-video-gallery&quot;&gt;Vendor's Website&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://aviationweek.com/business-aviation/video-flight-enhanced-vision-system-and-without&quot;&gt;AvWeek&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When the videos get down close to the runway, you can pick out the &lt;strong&gt;&lt;em&gt;glowing&lt;/em&gt;&lt;/strong&gt; approach and runway lights, which is where EVS differs from pure FLIR.  With FLIR, you'd see (sort-of) the lights and any framework that they're mounted on, but they wouldn't particularly glow -- they might as well be off.  With EVS, the crew can fly a CAT I ILS and actually have the approach lights, runway, runway lights, etc all in sight at the 200' DH, even when the visibility is such that with the naked eye, none of that would be visible.  At major US airports, CAT III approaches are often available, but elsewhere they may be rare or nonexistent.  The EVS capability has the promise of allowing crews to successfully land out of a Cat I approach (i.e. at an airfield that only has Cat I ground equipment) even in Cat III weather; from the OP's quote, it looks like they already have approval to use it for Cat II conditions. And for a global carrier like FedEx, that's a capability worth having.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-17T01:03:31.597" LastActivityDate="2015-12-17T01:03:31.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23724" PostTypeId="1" CreationDate="2015-12-17T01:45:28.657" Score="5" ViewCount="1031" Body="&lt;p&gt;I believe that with the new breed of low latency VR displays such as the Oculus Rift, as well as associated control peripherals, the days of the large simulator are numbered. Crews can train together from different locations and each can be on their own moving chair, much cheaper to actuate than a full-hydraulics cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will VR based solutions replace simulators with physical displays for FAA certification purposes?&lt;/p&gt;&#xA;" OwnerUserId="12312" LastEditorUserId="12312" LastEditDate="2015-12-17T16:41:10.257" LastActivityDate="2015-12-17T17:40:40.390" Title="Will VR make large professional simulators obsolete?" Tags="&lt;commercial-aviation&gt;&lt;flight-training&gt;&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23725" PostTypeId="1" CreationDate="2015-12-17T02:31:27.777" Score="9" ViewCount="489" Body="&lt;p&gt;What is the model of this seaplane?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hBvWD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hBvWD.jpg&quot; alt=&quot;Seaplane&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12698" LastEditorUserId="11787" LastEditDate="2016-06-22T15:41:26.110" LastActivityDate="2016-06-22T15:41:26.110" Title="What is the make and the model of this seaplane?" Tags="&lt;aircraft-identification&gt;&lt;seaplane&gt;&lt;ultralight&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23726" PostTypeId="2" ParentId="23724" CreationDate="2015-12-17T03:44:38.703" Score="25" Body="&lt;p&gt;Based on the variety of tasks that are performed in a simulator that VR would have great trouble accurately replicating, I think the answer is likely, no.  There IS a role for &quot;simulators&quot; that are more accurately referred to as &quot;procedures trainers&quot; in that they are non-motion, but this has nothing to do with VR, as those don't use all that much visual display anyway.  Networked wargaming is a great capability that VR can &lt;em&gt;add&lt;/em&gt; to military simulations, but that's an addition to, not a replacement of, traditional simulators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a full-motion simulator, there are several things about the simulator that contribute to aircrew training, and the visuals are one important part.  The replication of the entire cockpit, including every switch, lever, display, keypad, and so on is another.  When I go to the sim and practice emergency procedures, each control reacts exactly as it does in the aircraft: where I look and where I reach to put my eyes and then my hand on each control, how hard I need to pull to get the desired effect, and so on.  And where I'm reaching with my sitting height and arm's reach is ever so slightly different than another pilot does.  We both get the same control, but it's farther below a tall pilot's eye line than a short pilot's. (Slightly over-simplified, but the basic point remains.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We also do a fair amount of manipulation of the Flight Management Computer while in the simulator, which involves typing.  Not to say that typing isn't possible in VR, but it's not exactly the same as typing on a physical keyboard.  And we're using the same physical checklists and iPad EFB's that we do in the aircraft; not sure how well VR can mimic those.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when you consider all the parts &amp;amp; pieces that make up the modern simulator &amp;amp; its considerable cost, the physical replication of the cockpit probably isn't something you're going to be able to remove in favor of VR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For basic flying training, some of these sorts of factors are less important, as the basic flying skills you learn on one trainer transfer quite well to another trainer, even with a different cockpit layout.  But for basic flying training, not only the visual but also the vestibular and &quot;seat of the pants&quot; elements are more important.  While VR goggles like Occulus Rift are probably cheaper than several large display panels for providing the out-the-window visuals, these days high quality visual displays aren't the most expensive part of most simulators, and VR can't simulate the seat-of-the-pants sensation of accelerating, stopping, turbulence, and the like without some sort of motion actuators -- hydraulic or electric.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, for networked purposes (i.e. wargaming where Air Force elements from multiple bases across the country or globe can participate without the time &amp;amp; expense of getting to, say, Nellis AFB for a Red Flag), VR has amazing potential.  But to the extent that each pilot still has his own realistic cockpit &amp;amp; switches, what's driving the big gains is more the network than the VR... you can network an existing visual display with about the same hardware as you'd network the Rift devices.  To the extent that the &quot;reality&quot; of the precise cockpit can be sacrificed, then the VR probably makes for fabulous gains -- units practicing their tactics, rather than precise switchology. Sometimes that's a perfectly acceptable tradeoff; other times, not so much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But until the tactile feedback of VR is good enough that I can use it to practice putting my hand on a lever, pulling it out of its detent in &quot;this&quot; direction with &quot;this much&quot; force required for &quot;this much&quot; travel, then pushing it down &quot;this far&quot; with &quot;this much&quot; force until it hits the stop &quot;here,&quot; I really doubt that VR will replace the high-dollar flight simulators used in military and airline training.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-17T04:13:56.703" LastActivityDate="2015-12-17T04:13:56.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23728" PostTypeId="2" ParentId="23725" CreationDate="2015-12-17T08:33:17.613" Score="6" Body="&lt;p&gt;This is a Progressive Aerodyne &lt;a href=&quot;http://www.searey.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SeaRey&lt;/a&gt;, a kit aircraft. Also on:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Progressive_Aerodyne_SeaRey&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; and&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=imQ0d4oP3J4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Youtube&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;About 500 of this make had been built up to 2011 according to the Wikipedia article.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J58hi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J58hi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://light-sport-hangar-flyin.blogspot.fr/2011/02/hot-off-water.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Light Sport Hangar Flyin'&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is seemingly registered in the Philippines (&quot;RP&quot;), I read that at some point experimental aircraft had been grounded in the Philippines, but don't know if this was temporary only.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-12-17T08:47:14.623" LastActivityDate="2015-12-17T08:47:14.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23730" PostTypeId="1" AcceptedAnswerId="23732" CreationDate="2015-12-17T14:03:49.813" Score="6" ViewCount="7687" Body="&lt;p&gt;I was looking at a helicopter performance chart and it listed two values in feet, identified as &quot;Hover in ground effect (HIGE)&quot; and &quot;Hover outside of ground effect (HOGE).&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do these numbers mean, and why are they significant?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2015-12-17T14:59:42.413" Title="What is the significance of hover performance in helicopters (HIGE, HOGE)?" Tags="&lt;helicopter&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23731" PostTypeId="1" AcceptedAnswerId="23733" CreationDate="2015-12-17T14:51:01.220" Score="5" ViewCount="1617" Body="&lt;p&gt;Does &quot;clear of clouds&quot; mean you cannot touch a cloud or does it mean that that Class B airspace must not have any clouds in it?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2015-12-17T15:03:17.757" LastActivityDate="2015-12-17T15:07:24.667" Title="What does &quot;Clear Of Clouds&quot; mean in reference to Class B Airspace in the United States?" Tags="&lt;faa-regulations&gt;&lt;class-b-airspace&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23732" PostTypeId="2" ParentId="23730" CreationDate="2015-12-17T14:59:42.413" Score="3" Body="&lt;p&gt;Ground effect is a condition where the performance of the aircraft increases while operating near a firm surface. In general, a helicopter is considered to be in ground effect when it is hovering less than one-half of its rotor diameter from the ground and the effects become negligible when the helicopter is more than a rotor diameter above the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While hovering near the ground, the induced velocity at the rotor is reduced, which reduces the power requirement for a given rotor thrust (lift); equivalently, the rotor thrust is increased for given power due to ground proximity. Also, near ground, the rotor tip vortex is reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, the helicopter can hover at higher gross weight (equivalently, at higher altitude for given weight) in ground effect (HIGE) compared to out of ground effect (HOGE).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lCKaD.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lCKaD.gif&quot; alt=&quot;Ground effect&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from copters.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, the altitude at which a helicopter can hover at a given weight (and atmospheric conditions) is given for both HIGE and HOGE conditions. HOGE is much more restrictive compared to the HIGE. For example, the following image compares the hoer performance of R44 helicopter in and out of ground effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BG2hH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BG2hH.png&quot; alt=&quot;R44 HOGE&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Data from helicopterforum.verticalreference.com and aneclecticmind.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a sense, HOGE represents the absolute limit of the helicopter performance and it should be considered for operational calculations where there is no availability of rigid surfaces for vertical takeoff and landing or their presence is not confirmed.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-17T14:59:42.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23733" PostTypeId="2" ParentId="23731" CreationDate="2015-12-17T15:02:56.550" Score="5" Body="&lt;p&gt;That specific phrasing means that you can't touch a cloud. See the VFR minimums in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1155&quot;&gt;14 CFR 91.155&lt;/a&gt;, where it says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;no person may operate an aircraft under VFR when the flight visibility&#xA;  is less, or at a distance from clouds that is less, than that&#xA;  prescribed for the corresponding altitude and class of airspace in the&#xA;  following table [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The table lists the &quot;distance from clouds&quot; in class B as &quot;clear of clouds&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also find it in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot;&gt;AIM section 3-2-3&lt;/a&gt; on class B airspace, and in other sections about SVFR, visual approaches etc. where a requirement for those procedures is to remain clear of clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual cloud cover in the class B airspace is reported by METARs and ATIS.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-17T15:02:56.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23734" PostTypeId="2" ParentId="23731" CreationDate="2015-12-17T15:07:24.667" Score="3" Body="&lt;p&gt;It means that the pilot should not touch the clouds in VFR. From CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=dca6a2ec1a68a68db444d85d333641f1&amp;amp;mc=true&amp;amp;node=se14.2.91_1155&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.115&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HCDNC.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HCDNC.png&quot; alt=&quot;VFR&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-17T15:07:24.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23735" PostTypeId="1" AcceptedAnswerId="23738" CreationDate="2015-12-17T15:24:14.847" Score="29" ViewCount="7409" Body="&lt;p&gt;Are there any reasons other than political why Russian jets don't sell?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a case study, let's compare Sukhoi Superjet and Mitsubishi  Regional Jet. Despite being delayed several times, Mitsubishi has secured more orders than Sukhoi. Similarly, Embraer and Bombardier aircraft sell much more than the Sukhoi Superjet. Many new airlines continue to go to with Embraer and Bombardier. Despite promising lower running, maintenance, purchasing costs, why doesn't this aircraft secures orders? &lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="15311" LastEditDate="2018-01-25T22:02:28.343" LastActivityDate="2018-01-25T22:02:28.343" Title="Why don't Russian aircraft sell as much as their European/American counterparts?" Tags="&lt;aircraft-purchase&gt;&lt;russia&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23737" PostTypeId="2" ParentId="23735" CreationDate="2015-12-17T16:47:31.183" Score="8" Body="&lt;p&gt;I think reputation has a lot to do with this, I'm sure there are Russian aircraft out there that have outstanding safety records, but media has focused on some high-profile accidents as well as shoddy/corrupt government.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, certification is probably the other barrier, the bigger the aircraft the more expensive it is to certify it for various civil aviation authorities.&#xA;I think EASA and FAA have lots of rules/ standards worked out among themselves, but I don't think the Russian authority is well integrated.&lt;/p&gt;&#xA;" OwnerUserId="12312" LastActivityDate="2015-12-17T16:47:31.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23738" PostTypeId="2" ParentId="23735" CreationDate="2015-12-17T16:53:56.520" Score="40" Body="&lt;p&gt;If you take out the political angle (which is by far, the most important), there are a number of reasons for this.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Basically, the Russians have a serious image problem. Russian (and Soviet) aircraft have a reputation for poor quality, reliability and safety issues. This will take a long time to fix. In contrast, Japanese have no such problems (In fact, the MRJ boasts of '&lt;a href=&quot;http://www.flythemrj.com/&quot;&gt;legendary Japanese reliability&lt;/a&gt;') &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is not easy to make airlines switch from an existing aircraft. Most airlines have a huge system built around the aircraft they operate (In fact, quite a few regional carriers operate only a single aircraft type). It would take enormous amount of investment in time and money to shift to a new aircraft and it would take a large incentive for them to put their eggs in a new basket.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;US is probably the most important market at present and operating there gives other airlines a lot of confidence to buy the jet. If you see the orders for MRJ, most are from US (In fact, almost all orders are from either US or Japan). The Superjet, in contrast, hasn't even applied for FAA certification as far as I know.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Promising and delivering lower costs are completely different things. Airlines are more prone to believe companies that have a proven track record of manufacturing civil aircraft than a newcomer. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Superjet is the first airliner to be developed in Russia since the end of cold war. As such there are questions about its industrial capability and quality control processes. Mitsubishi, on the other hand is engaged in a number of aircraft projects (it makes more than a third of 787 structure).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sukhoi has to build a supply chain and support system from scratch (Superjet has a number of foreign components). Again, in the extremely cost sensitive airline industry with tight schedules, there is a perception that the Russian aircraft will not be supported as well as their western counterparts (For example, Boeing boasts of a &lt;a href=&quot;http://www.boeing.com/commercial/737max/&quot;&gt;&gt;99% dispatch reliability&lt;/a&gt; for 737)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-17T16:53:56.520" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23739" PostTypeId="1" AcceptedAnswerId="23779" CreationDate="2015-12-17T18:08:08.610" Score="12" ViewCount="2880" Body="&lt;p&gt;Many years ago I had an interesting discussion with a friend (while drinking). We were discussing what would happen if a helicopter was placed into a sphere of some size (slightly larger than the helicopter, a few times larger than the helicopter, etc.). Assume the sphere is filled with air at standard temperature and pressure, and there is standard 1G gravity pulling in one direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the helicopter maintain flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe it might, for a very short time, until the air starts circulating in a (relatively) stable manner, causing the &quot;natural flow&quot; of air to be already descending when it encounters the rotor disc, therefore reducing lift to nearly nothing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious what an expert might think. If this is off-topic, mark it as such and I'll delete the question. Adding more useful tags I don't know about might also be helpful. :)&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="167" LastEditDate="2015-12-19T05:48:06.653" LastActivityDate="2020-05-05T15:24:51.737" Title="Can a helicopter operate continuously in a small, enclosed, sealed environment?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="4" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="23740" PostTypeId="1" CreationDate="2015-12-17T18:49:49.363" Score="7" ViewCount="2373" Body="&lt;p&gt;Is this the shortest route served by an Airbus A320? Port Louis to Saint-Denis, 231 km (144 mi). Air Mauritius flight MK248.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yZCJJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yZCJJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="19" LastEditDate="2015-12-28T09:37:23.977" LastActivityDate="2018-10-07T20:58:23.303" Title="Is this the shortest route served by an Airbus A320?" Tags="&lt;airbus-a320&gt;&lt;short-haul&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23741" PostTypeId="2" ParentId="64" CreationDate="2015-12-17T19:15:07.297" Score="1" Body="&lt;p&gt;In addition to the FAR and AIM, most commercial operators (and savvy private operators) follow guidance in Advisory Circulars.  These are voluntary procedures that describe recommendations on best practices to stay legal and safe.&lt;/p&gt;&#xA;&lt;p&gt;Since you specifically mention commercial operations, &lt;strong&gt;AC 120-74b&lt;/strong&gt; is &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1020233&quot; rel=&quot;nofollow noreferrer&quot;&gt;worth a read&lt;/a&gt;.  It applies only to taxi procedures but there are hundreds of other ACs about all kinds of topics.  Beginning on page 11 there are several pages about lights on the ground:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) &lt;strong&gt;Engines Running.&lt;/strong&gt; Turn on the &lt;em&gt;rotating beacon&lt;/em&gt; whenever an engine is running.&lt;/p&gt;&#xA;&lt;p&gt;(b) &lt;strong&gt;Taxiing.&lt;/strong&gt; Prior to commencing taxi, turn on &lt;em&gt;navigation, position, anti-collision, and logo lights, if available.&lt;/em&gt; To signal intent to other pilots, turn on the taxi light when the aircraft is moving or intending to move on the ground, and turn it off when stopped or yielding or as a consideration to other pilots or ground personnel. Strobe lights should not be illuminated during taxi if they will adversely affect the vision of other pilots or ground personnel.&lt;/p&gt;&#xA;&lt;p&gt;(c) &lt;strong&gt;Crossing a Runway.&lt;/strong&gt; &lt;em&gt;All exterior lights&lt;/em&gt; should be illuminated when crossing a runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There is a corresponding AC created toward flight training and single pilot ops as well.&lt;/p&gt;&#xA;" OwnerUserId="7365" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-06-14T20:14:04.780" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23742" PostTypeId="2" ParentId="23740" CreationDate="2015-12-17T20:13:25.140" Score="12" Body="&lt;p&gt;&lt;a href=&quot;http://www.routesonline.com/news/29/breaking-news/252206/fastjet-to-introduce-shortest-regular-a320-family-service-as-it-returns-to-zanzibar/&quot; rel=&quot;noreferrer&quot;&gt;This site seems to indicate&lt;/a&gt; that they had the shortest route using the A-320 family of aircraft at just over 70km. The page also shows a list of flights, and it looks like one of them is listed at 58km. Based on that list, it looks like your 231km flight wouldn't even break the top 10.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0YyF1.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0YyF1.png&quot; alt=&quot;Short A-320 Routes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its difficult to search based on the length of the route and the aircraft type. As far as I can find though, 58km ACE-&gt;FUE shortest scheduled route for the A-320.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-17T20:18:32.650" LastActivityDate="2015-12-17T20:18:32.650" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23743" PostTypeId="1" AcceptedAnswerId="23745" CreationDate="2015-12-17T20:28:12.090" Score="19" ViewCount="21068" Body="&lt;p&gt;It seems these terms are used interchangeably. Are they the same thing? Do they all refer to the points in space that are given 5-letter names?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-05-01T15:26:55.783" LastActivityDate="2020-09-02T05:15:10.487" Title="What is the difference between a fix, a waypoint and an intersection?" Tags="&lt;navigation&gt;&lt;terminology&gt;&lt;waypoint&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="23744" PostTypeId="2" ParentId="23739" CreationDate="2015-12-17T20:31:08.327" Score="7" Body="&lt;p&gt;A serious danger to helicopter flight is flying in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Vortex_ring_state&quot; rel=&quot;noreferrer&quot;&gt;vortex ring state&lt;/a&gt;, causing a stall.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Essentially, the helicopter descends into its own downwash. When the condition arises, increasing the rotor power merely feeds the vortex motion without generating additional lift&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Several helicopters have crashed as a result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This state would be very quickly established for a helicopter in a confined container.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MC3sH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MC3sH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2015-12-17T20:31:08.327" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23745" PostTypeId="2" ParentId="23743" CreationDate="2015-12-17T20:32:51.917" Score="17" Body="&lt;p&gt;No, they are not interchangeable and indeed, have well defined meanings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;fix&lt;/strong&gt; is an arbitrary point in space used to establish current position calculated by referring to external references.  You take a fix to determine where you are &lt;strong&gt;now&lt;/strong&gt;.  A fix might be permanent, for example a compulsory reporting point, or it might be determined by the pilot in advance in order to fly a non-airways route (e.g. when flying VFR) and then checked along the way using dead reckoning and reference to external systems or features to check that the plan is being flown accurately.  It might also be requested by ATC, e.g. &quot;report when overhead the railroad yard&quot; or calculated to establish where you are, e.g. taking a fix from an astrolabe on a night oceanic crossing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i9Gct.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i9Gct.jpg&quot; alt=&quot;Illustration of ways to define a fix&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://wiki.flightgear.org/Radio_navigation&quot; rel=&quot;noreferrer&quot;&gt;From FlightGear&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;strong&gt;waypoint&lt;/strong&gt; is fixed point in 2D space (latitude and longitude) used to define points along a route.  They are named, and are referenced in a plan.  You fly from one waypoint to the next, along a route.  A waypoint is where you are flying to.  It is normally positioned where there is a change of course or altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the navigation positions given the &lt;a href=&quot;http://www.golfhotelwhiskey.com/funny-waypoint-names/&quot; rel=&quot;noreferrer&quot;&gt;5 letter names&lt;/a&gt; you ask about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d933S.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d933S.gif&quot; alt=&quot;Illustration of waypoints along a route&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sailtrain.co.uk/gps/functions.htm&quot; rel=&quot;noreferrer&quot;&gt;From SailTrain&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Tn2CB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tn2CB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;strong&gt;intersection&lt;/strong&gt; is where two airways cross. Here, the Victor airways 15 and 76 cross at the intersection.  In this particular case, the chart symbol further shows that the V76 airway does not use the intersection, in which case the chart will include a note of the intersection usage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9kgQk.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9kgQk.gif&quot; alt=&quot;Example of an intersection on an IFR chart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://delta.jepptech.com/jifp/help/Airway_and_Route_Components.htm&quot; rel=&quot;noreferrer&quot;&gt;From Jepptech&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now sorry about this, but having said they are not interchangeable, it's not that simple.  A waypoint is also a fix (a fix is any 2D point).  But you do not call a waypoint a fix.  A fix is a 2D point which is not a waypoint, but is used for navigation.  A fix might be also be a lat and long defining the beginning of an arrival or departure procedure where you leave or enter an airway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An intersection is also a fix, but it only exists to define where two airways cross (or where any other 2 lines cross, e.g. the 170 degree and 046 degree radial from two NDB beacons) so is called an intersection, not a fix.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that sense, they are all fixes but the name has meaning.  &lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2015-12-17T23:42:53.730" LastActivityDate="2015-12-17T23:42:53.730" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23746" PostTypeId="2" ParentId="19424" CreationDate="2015-12-17T20:53:29.240" Score="2" Body="&lt;p&gt;On the tornado the box at the top of the fin is the RHWR basically to warn the A/C if there is a radar locking on to them. The lower protuberance like the typhoon is an intercooler intake.&lt;/p&gt;&#xA;" OwnerUserId="12708" LastActivityDate="2015-12-17T20:53:29.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23747" PostTypeId="1" AcceptedAnswerId="23748" CreationDate="2015-12-18T01:06:30.307" Score="28" ViewCount="13076" Body="&lt;p&gt;Some high-speed military aircraft like the SR-71 had real heating problems, but airliners also travel almost at the speed of sound, use most of their fuel to make up for frictional losses, so I would presume that their hulls heat up. They are also cooled by the airflow, but at what temperature does equilibrium set in during cruise? I remember that airliners don't seem to be very hot when you touch them after landing, but they have had time to cool down in the slow winds during descent.&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="15311" LastEditDate="2019-04-13T08:40:53.840" LastActivityDate="2019-04-13T08:40:53.840" Title="What is the typical temperature of an airliner's hull during flight?" Tags="&lt;aerodynamics&gt;&lt;airliner&gt;&lt;temperature&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23748" PostTypeId="2" ParentId="23747" CreationDate="2015-12-18T02:37:26.463" Score="31" Body="&lt;p&gt;There are two primary factors that affect the skin temperature of an aircraft in flight: the air temperature, and the speed of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air temperature where airliners cruise is relatively cold, around &lt;a href=&quot;http://www.engineeringtoolbox.com/standard-atmosphere-d_604.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;-54 °C at 35,000 feet&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a body like an aircraft moves through air, it compresses the air, which causes the air temperature to rise. The maximum temperature rise will be if the air is completely stopped, such as at a leading edge. This is called the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1640/what-is-the-difference-between-oat-rat-tat-and-sat&quot;&gt;total air temperature&lt;/a&gt;, and the amount that the temperature rises is called the ram rise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a &lt;a href=&quot;https://en.wikipedia.org/wiki/Total_air_temperature&quot; rel=&quot;nofollow noreferrer&quot;&gt;simple formula&lt;/a&gt; to find the ram rise:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$RR = \frac{V^2}{87^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;… where $RR$ is in Kelvin, and $V$ is the true airspeed in knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a typical airliner cruising speed of 500 knots gives a temperature of 33 degrees. This brings the total air temperature to -22 °C, which is still quite cold. At places other than the leading edge, the temperature rise will be less. This is why &lt;a href=&quot;https://aviation.stackexchange.com/questions/21055/does-cargo-heat-failure-require-a-diversion-what-about-if-there-are-live-animal&quot;&gt;cargo holds will need heaters to be safe for live animals&lt;/a&gt;, even being insulated and pressurized. Airliners just don't fly fast enough to produce a significant amount of heating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the SR-71 could fly at over 1,910 kts, which gives a ram rise of 482 °C. The air doesn't get much colder as you climb to the altitudes where the SR-71 flew, so this gives a total air temperature of over 400 °C. Speed makes a huge difference.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2015-12-18T08:29:26.480" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="23749" PostTypeId="1" CreationDate="2015-12-18T03:50:17.090" Score="11" ViewCount="8902" Body="&lt;p&gt;When pilots learn to talk on the radio they can generally learn that the word &quot;roger,&quot; when used on the radio, is a way to acknowledge that a message was received. What is the textbook definition of the meaning of this word when used on the radio? Also, what is the origin of this word?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2018-09-06T22:01:55.957" LastActivityDate="2018-09-06T22:01:55.957" Title="What is the true meaning of the word &quot;roger&quot; when used on the radio? What is its origin?" Tags="&lt;radio-communications&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23750" PostTypeId="1" AcceptedAnswerId="23752" CreationDate="2015-12-18T03:51:53.367" Score="4" ViewCount="46081" Body="&lt;p&gt;Pilots often learn to use the word &quot;wilco&quot; on the radio through contextual interpretation. During my experience as a pilot communicating on the radio I have often observed pilots using the word &quot;wilco&quot; improperly. What is the true meaning of the word &quot;wilco&quot; and what is its origin?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2015-12-18T04:04:52.523" LastActivityDate="2016-12-21T14:27:11.087" Title="What is the true meaning of the word “wilco” when used on the radio? What is its origin?" Tags="&lt;radio-communications&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23751" PostTypeId="2" ParentId="23749" CreationDate="2015-12-18T03:58:53.190" Score="8" Body="&lt;p&gt;The word &quot;roger&quot; is used to acknowledge that a message was received, and goes back to the early uses of radio. &lt;a href=&quot;https://en.wikipedia.org/wiki/Voice_procedure&quot;&gt;From Wikipedia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This usage comes from the initial R of received: R was called Roger in the radio alphabets or spelling alphabets in use by the military at the time of the invention of the radio&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-12-18T03:58:53.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23752" PostTypeId="2" ParentId="23750" CreationDate="2015-12-18T04:02:25.813" Score="20" Body="&lt;p&gt;&quot;Wilco&quot; is short for the phrase &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Voice_procedure&quot; rel=&quot;nofollow noreferrer&quot;&gt;will comply&lt;/a&gt;,&quot; meaning that the speaker will follow the instructions to which they are replying. &lt;a href=&quot;http://www.merriam-webster.com/dictionary/wilco&quot; rel=&quot;nofollow noreferrer&quot;&gt;Merriam-Webster&lt;/a&gt; places the origin at 1938, some time after the invention of radio, likely in military usage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the phrase &quot;roger wilco&quot; is sometimes used, &lt;a href=&quot;http://jcs.dtic.mil/j6/cceb/acps/acp125/ACP125F.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;it is considered redundant&lt;/a&gt; since the &quot;roger&quot; (&lt;a href=&quot;https://aviation.stackexchange.com/q/23749/1696&quot;&gt;meaning &quot;received and understood&quot;&lt;/a&gt;) is implied.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-19T00:48:58.980" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23753" PostTypeId="1" AcceptedAnswerId="25325" CreationDate="2015-12-18T04:02:48.630" Score="9" ViewCount="1127" Body="&lt;p&gt;Let's suppose that a flight is being conducted under 14 CFR 135. The airplane is certified for single pilot operations, but two pilots who are both rated as PIC on the 135 certificate occupy the pilot seats. One of the pilots is a CFI. Does anything in 14 CFR 135 prevent the CFI from giving dual given time to the PIC while he flies?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="62" LastEditDate="2016-01-02T01:56:43.860" LastActivityDate="2016-02-17T02:33:35.053" Title="Can instruction be given during a flight conducted under 14 CFR 135?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;far-135&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23754" PostTypeId="1" AcceptedAnswerId="23763" CreationDate="2015-12-18T06:25:51.320" Score="0" ViewCount="218" Body="&lt;p&gt;When the transponder fails, would ATC pickup my altitude response from my Stratus or any other ADS-B out instead? Is it legal to do so?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2015-12-18T13:37:54.403" Title="In case of transponder failure, can I use my ADS-B out (Stratus II) serve as a back-up?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23755" PostTypeId="1" CreationDate="2015-12-18T09:52:56.747" Score="9" ViewCount="4375" Body="&lt;p&gt;I was wondering if the same captain and first officers always fly together for some time as some sort of a team or are they mixed around in every flight? I suppose if you have one plane that is the case but what happens in huge airlines such as emirates? Wouldn't it also be a drawback always flying with someone that you do not actually know?&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-12-18T15:10:07.283" Title="Do captains and first officers always fly together or are they mixed?" Tags="&lt;pilots&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23756" PostTypeId="2" ParentId="9112" CreationDate="2015-12-18T09:59:12.283" Score="2" Body="&lt;p&gt;Aircraft on the ground don't make money, so airlines only ever re-paint their aircraft when needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a regulatory requirement that an aircraft undergoes a thorough inspection - a &quot;D Check&quot;, approximately every 6 years. As part of this D-check, the paint is stripped off the aircraft to allow the hull to be thoroughly inspected. As such, most airlines will wait until the aircraft is due for a D check before repainting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from that, they will only repaint when absolutely necessary, i.e if the paint is deteriorating, or if they change livery and decide they want to remove the old livery quicker than waiting for aircraft to require a D check.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastActivityDate="2015-12-18T09:59:12.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23757" PostTypeId="1" AcceptedAnswerId="23765" CreationDate="2015-12-18T10:05:52.717" Score="7" ViewCount="2502" Body="&lt;p&gt;Why is it that these planes had vertical stabilisers that were noticeably smaller in proportion the aircraft itself to other aircraft? I understand that they had the engines mounted on the tail but couldn't the surfaces have been made larger? Doesn't this make it more difficult to control during flight as the surface is way smaller? Maybe is had some other mechanism in the engine that could compensate for the smaller area of the vertical fin?&lt;/p&gt;&#xA;&lt;p&gt;I've added some images of the DC10, the TriStar, Boeing 767 and A310 which are aircraft that are sort of comparable in era and age and the most interesting one is the TriStar which so small:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fY7X7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fY7X7.jpg&quot; alt=&quot;DC10&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/63fh5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/63fh5.jpg&quot; alt=&quot;L1011&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/QLRkc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QLRkc.jpg&quot; alt=&quot;Airbus A310&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Gna4i.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gna4i.jpg&quot; alt=&quot;Boeing 767&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="22726" LastEditDate="2021-04-10T01:28:29.173" LastActivityDate="2021-04-10T01:28:29.173" Title="Why is the DC10/MD11/TriStar vertical stabilizer noticeably smaller than other contemporary aircraft?" Tags="&lt;tail&gt;&lt;vertical-stabilizer&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23758" PostTypeId="2" ParentId="23755" CreationDate="2015-12-18T10:26:37.743" Score="7" Body="&lt;p&gt;Do captains and first officers always fly together? No. For large airlines, it would be the exception, rather than norm to fly with the same First Officer several times in a year. For example, consider &lt;a href=&quot;https://en.wikipedia.org/wiki/KLM&quot;&gt;KLM&lt;/a&gt;- it has less 200 aircraft in its fleet, but well over 2000 pilots. Even making allowance for type certification, there are quite a few pilots for each aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I doubt there would be any drawback in working with a new FO for the first time. Both are fully qualified to fly the plane in all regimes of flight, and usually do so in alternating turns. As an example, the pilots who landed the &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;US Airways Flight 1549&lt;/a&gt; safely in Hudson &lt;a href=&quot;http://www.osifv.com/newsroom/2015/04/21/miracle-hudson-copilot-speaks-osi-conference&quot;&gt;met for the first time&lt;/a&gt; during that flight, though having enormous experience.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Of course, there can be exception to this rule. For example, &lt;a href=&quot;http://www.theguardian.com/uk/2004/jan/28/concorde.world&quot;&gt;only 20 pilots&lt;/a&gt; were trained to fly the seven Concorde jets of British Airways and as such, they would've flown together more often than others.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-18T10:26:37.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23759" PostTypeId="2" ParentId="23757" CreationDate="2015-12-18T10:36:29.987" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Doesn't this make it more difficult to control during flight as the surface is way smaller?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Design&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Rudder authority becomes most important (arguably) when one wing-mounted engine fails or is shut down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To combat this on the DC10 &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The rudder takes up a large proportion of the area of the fin&lt;/li&gt;&#xA;&lt;li&gt;The rudder has dual articulation - there are two vertical hinges.&#xA;This gives the rudder greater effectiveness.&lt;/li&gt;&#xA;&lt;li&gt;The wing-mounted engines are mounted closer to the fuselage.&#xA;This reduces the yawing effect of a dead engine.&lt;/li&gt;&#xA;&lt;li&gt;The wing-mounted engines provide only 1/3rd of the thrust instead of &#xA;half as with a 2-engine aircraft, &#xA;so the effect of one engine out is less.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The 747SP is another aircraft with dual articulation in the rudder.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Operating Procedures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It may be the case that the DC10 operating procedures had lower limits than some other aircraft for cross-wind on landing.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2015-12-18T17:19:13.087" LastActivityDate="2015-12-18T17:19:13.087" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23760" PostTypeId="1" AcceptedAnswerId="23761" CreationDate="2015-12-18T10:50:00.767" Score="21" ViewCount="4669" Body="&lt;p&gt;As a follow-up question to &lt;a href=&quot;https://aviation.stackexchange.com/questions/23747/what-is-the-typical-temperature-of-an-airliners-hull-during-flight/23748#23748&quot;&gt;What is the typical temperature of an airliner's hull during flight?&lt;/a&gt; I wonder how very fast airplanes, such as the SR-71 mentioned, avoid overheating with a total air temperature outside of more than 400 degrees Celsius. &lt;/p&gt;&#xA;" OwnerUserId="8159" LastEditorUserId="15311" LastEditDate="2019-03-24T12:58:55.087" LastActivityDate="2021-05-18T13:45:20.123" Title="How do fast-flying aircraft avoid overheating?" Tags="&lt;aerospace-materials&gt;&lt;temperature&gt;&lt;sr-71&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23761" PostTypeId="2" ParentId="23760" CreationDate="2015-12-18T12:17:59.227" Score="33" Body="&lt;p&gt;To avoid overheating, the usual trick is to select the right material:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; used a special aluminium alloy, called &lt;a href=&quot;https://en.wikipedia.org/wiki/Hiduminium&quot; rel=&quot;noreferrer&quot;&gt;Hiduminium&lt;/a&gt;, which had higher strength at elevated temperatures and allowed the Concorde to cruise at Mach 2.02. Aluminium melts at 660°C.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25&quot; rel=&quot;noreferrer&quot;&gt;MiG-25&lt;/a&gt; used stainless steel instead of aluminium to make its top speed of Mach 3.1 possible (top speed without engine damage was Mach 2.83). Titanium would had been even better, but was expensive and difficult to work with at that time. Stainless steel melts between 1400°C and 1450°C.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;XB-70&lt;/a&gt; used &lt;a href=&quot;https://en.wikipedia.org/wiki/Titanium&quot; rel=&quot;noreferrer&quot;&gt;titanium&lt;/a&gt; in addition to stainless steel. Its cruise speed was also Mach 3.0. Titanium melts at 1668°C.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;noreferrer&quot;&gt;SR-71&lt;/a&gt; used &lt;a href=&quot;https://en.wikipedia.org/wiki/Titanium&quot; rel=&quot;noreferrer&quot;&gt;titanium&lt;/a&gt; for 85% of its structure to allow a cruising speed of Mach 3.2.&lt;/li&gt;&#xA;&lt;li&gt;The X-15 was built from &lt;a href=&quot;https://en.wikipedia.org/wiki/Inconel&quot; rel=&quot;noreferrer&quot;&gt;Inconel&lt;/a&gt;-X, a nickel-chromium alloy which has excellent strength at high temperature (it starts to melt at 1393°C) and allowed it to go up to Mach 6.5.&lt;/li&gt;&#xA;&lt;li&gt;The Space Shuttle used a ceramic insulation on top of the load-carrying aluminium structure which kept the heat away from the structure during descent. Note that the Shuttle had to be &lt;a href=&quot;http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/eclss/atcs.html&quot; rel=&quot;noreferrer&quot;&gt;connected to a heat sink&lt;/a&gt; to cool the on-board systems after landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The next trick is to fly higher up where air is less dense. Lower density does not reduce the air temperature, but it reduces the heat flow so the airframe will settle at a lower temperature. Remember that the eventual heat is the combination of convection, radiation and heat conductivity. Flying high up allows especially the top surface to radiate heat freely into the black of space above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hottest aircraft ever was the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot; rel=&quot;noreferrer&quot;&gt;North American X-15&lt;/a&gt; A-2. For a speed record attempt, the whole aircraft was covered with &lt;a href=&quot;http://www.ipmsstockholm.org/magazine/2004/03/stuff_eng_x15.htm&quot; rel=&quot;noreferrer&quot;&gt;pink, ablative paint&lt;/a&gt; so the process of sublimation would carry some more heat away. To protect the paint from liquid oxygen, a white topcoat was applied also.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w1Vxn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w1Vxn.jpg&quot; alt=&quot;X-15 A-2 shortly after being dropped from the B-52 carrier&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-15 A-2 shortly after being dropped from the B-52 carrier (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/4/4d/X-15A2_NB-52B_3.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the small barrel under the lower fin: This was a ramjet which was test-flown on this occasion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lrant.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lrant.jpg&quot; alt=&quot;Damage to the ventral stabilizer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Damage to the ventral stabilizer. The ramjet separated prematurely due to frictional heating (picture &lt;a href=&quot;http://www.ipmsstockholm.org/magazine/2004/03/images/x15_08.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A third trick is to fly fast only for a short time. A heat-seeking air to air missile will easily reach Mach 3, but only for less than a minute. To keep the sensor cooled, a pressurized gas (argon or nitrogen) would be expanded (the &lt;a href=&quot;https://en.wikipedia.org/wiki/AIM-9_Sidewinder#AIM-9X&quot; rel=&quot;noreferrer&quot;&gt;AIM-9X&lt;/a&gt; even uses a &lt;a href=&quot;https://en.wikipedia.org/wiki/Applications_of_the_Stirling_engine#Stirling_cryocoolers&quot; rel=&quot;noreferrer&quot;&gt;stirling cryo-cooler&lt;/a&gt;). By heating the structure or using an internal heat sink, the limited heat load can be tolerated, albeit only for a very limited time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-11-19T19:44:00.680" LastActivityDate="2016-11-19T19:44:00.680" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23762" PostTypeId="2" ParentId="23760" CreationDate="2015-12-18T12:57:54.933" Score="8" Body="&lt;p&gt;There are multiple ways to avoid overheating.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The simplest method is to use a high temperature material- like Titanium in SR-71 or steel alloy in Mig-25; in Concorde, a special aluminum alloy (AU2GN) was used. In case of other aircraft, steel or Ti is used in stagnation points (like wing leading edges), while the other exposed surfaces are made out of other materials.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In SR-71, &lt;a href=&quot;http://www.airspacemag.com/military-aviation/what-blackbird-drinks-180953422/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;the fuel was used as a heat sink&lt;/a&gt; to dissipate the heat generated in the airframe.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In X-15, an &lt;a href=&quot;http://history.nasa.gov/x15lect/structur.html&quot; rel=&quot;noreferrer&quot;&gt;ablative insulation was used&lt;/a&gt; to overcome heating problems:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The airplane was covered with ablative insulation designed to permit flights to Mach 7.4. A silicone elastomeric ablator was sprayed on in variable thickness appropriate to the local heat loads. Leading edges were protected by a related erosion-resistant material applied in preformed sections&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aerothermodynamic design is important for high speed aircraft. For example, when NASA tested a dummy ramjet in X-15, the mounting pylon nearly failed due to interference heating, with leading-edge heating rates of the order of seven times compared to those without interference being estimated.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wpaov.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wpaov.jpg&quot; alt=&quot;X-15&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Failure of pylon due to interference heating from dummy ramjet&lt;/em&gt;, image from history.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To help reflect and radiate the high amount of heat produced during supersonic flight, the Concorde had a high-reflectivity white paint that was about twice as reflective as the white paint on other jets.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-18T12:57:54.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23763" PostTypeId="2" ParentId="23754" CreationDate="2015-12-18T13:31:52.143" Score="8" Body="&lt;p&gt;The Stratus does not broadcast. It recieves only. So that is no help.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you had a stand alone UAT ADS-B transmitter. It might continue to broadcast your altitude if your transponder failed. The UAT requires an altitude input and it must be from the same source that your transponder gets it. Sometimes that gets wired directly from a 2nd output of your altitude encoder (bypassing the transponder which gets it from the 1st output) in which case it would continue to broadcast altitude. Sometimes the altitude wiring goes from your encoder to your transponder, then the transponder has an output that sends it to your ADS-B UAT. In this case it might fail if the transponder fails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It might be useful to know that the ADS-B transmitter must broadcast your current transponder code (1200 for vfr). The UAT generally senses it automatically as the transponder broasdcasts it so you don't need to set it in 2 different controls. But if your transponder fails, it won't sense the code and may go into a fail mode on it's own (not sure about this though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advent of ADS-B brings no relaxing of the regulations regarding the requirement of using transponders.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="340" LastEditDate="2015-12-18T13:37:54.403" LastActivityDate="2015-12-18T13:37:54.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23764" PostTypeId="2" ParentId="23749" CreationDate="2015-12-18T13:51:17.747" Score="10" Body="&lt;p&gt;In the US, the &quot;textbook&quot; meaning is in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;ROGER&lt;/strong&gt; − I have received all of your last  transmission. It should not be used to answer a  question requiring a yes or a no answer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM 4-2-3&lt;/a&gt; gives an example of using it to acknowledge instructions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Acknowledge  with  your aircraft identification, either at the&#xA;  beginning or  at the end of your transmission, and one of the words &#xA;  “Wilco,” “Roger,” “Affirmative,” “Negative,” or  other appropriate&#xA;  remarks; e.g., “PIPER TWO ONE  FOUR LIMA, ROGER.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a counterpoint to that, when I first learned to fly in South Africa I was told never to use &lt;em&gt;Roger&lt;/em&gt; in transmissions because it doesn't tell the controller anything useful (obviously the FAA disagrees).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as for the etymology, that's already been covered in &lt;a href=&quot;https://aviation.stackexchange.com/a/23751/62&quot;&gt;another answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This usage comes from the initial R of received: R was called Roger in&#xA;  the radio alphabets or spelling alphabets in use by the military at&#xA;  the time of the invention of the radio&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-18T13:51:17.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23765" PostTypeId="2" ParentId="23757" CreationDate="2015-12-18T14:11:46.197" Score="13" Body="&lt;p&gt;Two characteristics drive vertical tail size in airliners:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Critical engine out: Here the tail needs to compensate the yawing moment of the live engine on one wing.&lt;/li&gt;&#xA;&lt;li&gt;Yaw damping: This is aided by a yaw damper, but enough damping must remain for the case of a failed damper. Especially the dutch roll eigenmode is driving tail size.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On the other hand the tail should not be bigger than absolutely necessary to keep drag and weight down. On the Tristar, the big intake added so much tail area that a relatively small tail was sufficient. Note that the engine intake on the Tristar is much longer than on the DC-10 because of the S-duct. The flow must be brought down to the engine without internal flow separation, which is made easier when the intake is longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since in the engine-out case only one third of total thrust creates the yawing moment which the tail needs to overcome compared to one half of the thrust in case of the A310, the vertical tails of both the Tristar and DC-10 are smaller relative to that of the A310. The A310 is a shortened version of the A300, so the reduction in fuselage length made an especially large vertical tail necessary. If you look at the vertical tails of the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_MD-80&quot; rel=&quot;noreferrer&quot;&gt;MD-80&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-62&quot; rel=&quot;noreferrer&quot;&gt;Il-62&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_VC10&quot; rel=&quot;noreferrer&quot;&gt;VC10&lt;/a&gt;, they are even smaller since very little yawing moment needs to be compensated in the engine-out case. Adding to this, the T-tail configuration makes the existing tail more effective due to the &lt;a href=&quot;http://www.j-mst.org/On_line/admin/files/30-04178_2578-2589_.pdf&quot; rel=&quot;noreferrer&quot;&gt;endplate effect&lt;/a&gt; (PDF!) of the horizontal tail on those three types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yOwgV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yOwgV.jpg&quot; alt=&quot;Vickers VC10 (left) and Tristar (right) tankers in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vickers VC10 (left) and Tristar (right) tankers in flight (picture &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/0/9/9/0672990.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-19T11:56:01.813" LastActivityDate="2015-12-19T11:56:01.813" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23766" PostTypeId="2" ParentId="23755" CreationDate="2015-12-18T14:48:54.223" Score="11" Body="&lt;p&gt;In airlines where pilots bid on monthly lines it is conceivable that a pair of pilots fly all month together. However, trip trading and reassignments rarely let this happen. It is far more common that a crew only stays together for a single &quot;pairing&quot; that lasts between 1 and 4 days (domestic 121 USA). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not a drawback to fly with new people because training emphasizes standard flying according to the FOM. Ideally, every pilot is exactly the same.&#xA;  Practically it is close enough that you can drop any two pilots from the same airline into an airplane and they more or less operate it exactly the same way. &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2015-12-18T15:10:07.283" LastActivityDate="2015-12-18T15:10:07.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23767" PostTypeId="2" ParentId="23750" CreationDate="2015-12-18T14:54:15.557" Score="8" Body="&lt;p&gt;In the US, the &quot;official&quot; meaning is in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;WILCO&lt;/strong&gt; − I have received your message, understand  it, and will comply with it&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Note that this is slightly different from &lt;a href=&quot;https://aviation.stackexchange.com/q/23749/62&quot;&gt;&lt;em&gt;roger&lt;/em&gt;&lt;/a&gt;, which is just an acknowledgement and doesn't mean that you will comply with anything.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 4-2-3&lt;/a&gt; mentions using it to acknowledge instructions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Acknowledge  with  your aircraft identification, either at the&#xA;  beginning or  at the end of your transmission, and one of the words &#xA;  “Wilco,” “Roger,” “Affirmative,” “Negative,” or  other appropriate&#xA;  remarks&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The problem I see with using &lt;em&gt;wilco&lt;/em&gt; is that you're confirming that you'll comply with an instruction, but if you don't also &lt;a href=&quot;https://aviation.stackexchange.com/q/279/62&quot;&gt;read back the instruction&lt;/a&gt; then the controller has no way to know what you're complying with. You might have misheard or misunderstood it, so you should repeat it. But if you repeat it, then &lt;em&gt;wilco&lt;/em&gt; is unnecessary. Outside the US, I was &lt;a href=&quot;https://aviation.stackexchange.com/a/23764/62&quot;&gt;originally taught&lt;/a&gt; never to use &lt;em&gt;roger&lt;/em&gt; or &lt;em&gt;wilco&lt;/em&gt; for that reason: it leaves the controller wondering what you really heard and what you're going to do next. But obviously as far as US aviation goes, both are completely acceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as for the etymology, that's already been covered in &lt;a href=&quot;https://aviation.stackexchange.com/a/23752/62&quot;&gt;another answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Wilco&quot; is short for the phrase &quot;will comply,&quot; meaning that the&#xA;  speaker will follow the instructions to which they are replying&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2015-12-18T14:54:15.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23768" PostTypeId="1" AcceptedAnswerId="23770" CreationDate="2015-12-18T17:00:54.740" Score="11" ViewCount="1444" Body="&lt;p&gt;It was asserted (tangentially) in &lt;a href=&quot;https://aviation.stackexchange.com/questions/23747/what-is-the-typical-temperature-of-an-airliners-hull-during-flight&quot;&gt;this question&lt;/a&gt; that airliners use most of their fuel to &lt;code&gt;overcome frictional losses&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is that a true statement? &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If so, approximately what percentage of fuel is used to overcome friction?&lt;/li&gt;&#xA;&lt;li&gt;If not, what is the major use of fuel? (Beyond the obvious 'to run the engines'.)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2020-03-25T15:53:09.163" Title="Do aircraft use the majority of their fuel to overcome friction?" Tags="&lt;airliner&gt;&lt;fuel&gt;&lt;efficiency&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23769" PostTypeId="1" AcceptedAnswerId="23775" CreationDate="2015-12-18T17:01:50.900" Score="-1" ViewCount="415" Body="&lt;p&gt;In &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; article, I read about the B747 testbed for the B777 GE90 engine. Where can I find more information on that airplane?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-12-18T21:11:42.440" Title="History and results of the GE90 B747 Test" Tags="&lt;aviation-history&gt;&lt;boeing&gt;&lt;boeing-747&gt;&lt;boeing-777&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-19T02:52:12.253" ContentLicense="CC BY-SA 3.0" />
  <row Id="23770" PostTypeId="2" ParentId="23768" CreationDate="2015-12-18T17:47:45.350" Score="2" Body="&lt;p&gt;For an aircraft in level flight, lift opposes the weight of the aircraft, and thrust from the engines opposes the &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/drag1.html&quot; rel=&quot;nofollow&quot;&gt;drag&lt;/a&gt; of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One form of drag is &lt;a href=&quot;https://en.wikipedia.org/wiki/Skin_friction_drag&quot; rel=&quot;nofollow&quot;&gt;skin friction drag&lt;/a&gt;. The statement you reference is in the context of skin heating, and the skin friction is the main way that the skin will be heating. Other significant sources of drag add energy to the air instead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.imamod.ru/~serge/arc/conf/ECCOMAS_2004/ECCOMAS_V2/proceedings/pdf/924.pdf&quot; rel=&quot;nofollow&quot;&gt;this paper&lt;/a&gt;, &lt;strong&gt;about half of an airliner's drag comes from skin friction&lt;/strong&gt;. This &lt;a href=&quot;https://books.google.com/books?id=bSq-cEf0EWsC&amp;amp;lpg=PA152-IA53&amp;amp;ots=iFOsyUItwO&amp;amp;pg=PA152-IA53#v=onepage&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;estimation of cruise drag for a business jet&lt;/a&gt; shows a similar breakdown. About a third of the drag is induced drag, which is the side effect of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To address the original statement, friction drag may account for the majority of fuel use, but not by very much. It is the largest source of drag but not always more than half of the total drag.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2015-12-18T21:32:13.937" LastActivityDate="2015-12-18T21:32:13.937" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23772" PostTypeId="1" AcceptedAnswerId="23774" CreationDate="2015-12-18T18:29:29.583" Score="3" ViewCount="4515" Body="&lt;p&gt;What does the circled r: ® mean in the Chart Supplement (A/FD)? You can see it here to the left of SOCAL APP/DEP CON:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/akMTY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/akMTY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="62" LastEditDate="2016-10-07T17:21:36.903" LastActivityDate="2016-10-07T17:21:36.903" Title="What does ® mean in the Chart Supplement (A/FD)?" Tags="&lt;airport&gt;&lt;chart-supplement&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23773" PostTypeId="2" ParentId="23772" CreationDate="2015-12-18T18:37:08.843" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;http://rowdy.msudenver.edu/~christib/wprof/aes180/AFDlegend.pdf&quot; rel=&quot;nofollow&quot;&gt;this legend&lt;/a&gt; for the A/FD, the symbol indicates that the approach/departure control has radar. This means that ATC can more accurately locate, track, and provide guidance to pilots.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-12-18T18:37:08.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23774" PostTypeId="2" ParentId="23772" CreationDate="2015-12-18T18:42:00.720" Score="4" Body="&lt;p&gt;According to the &lt;a href=&quot;http://aeronav.faa.gov/afd/10dec2015/SE_front_10dec2015.pdf&quot; rel=&quot;nofollow&quot;&gt;Chart Supplement (formerly the A/FD) legend&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;APP CON—Approach Control. The symbol ® indicates radar approach&#xA;  control&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DEP CON—Departure Control. The symbol  ®  indicates radar departure&#xA;  control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA has different approach &lt;a href=&quot;http://aspmhelp.faa.gov/index.php/OPSNET:_Facility_Classification&quot; rel=&quot;nofollow&quot;&gt;facilities classifications&lt;/a&gt;, a TRACON has radar but others don't. So you should see this symbol when the approach/departure services are provided by a TRACON or other radar facility.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-10-07T17:17:08.547" LastActivityDate="2016-10-07T17:17:08.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23775" PostTypeId="2" ParentId="23769" CreationDate="2015-12-18T20:06:52.890" Score="1" Body="&lt;p&gt;You may read more in this article:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.air-and-space.com/Boeing%20747-121%20General%20Electric%20Engine%20Testbed.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-121 General Electric Engine Testbed, c/n 19651&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As mentioned this is the B747 with construction number 19651.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this article above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On March 9,1992 the former Pan Am Boeing 747-121 was registered to&#xA;  General Electric Aircraft Engines (GEAE) at the Mojave Airport in&#xA;  Mojave, California.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;At the Mojave Airport General Electric removed all&#xA;  passenger coach seating from the former Pan Am 747 and installed three&#xA;  engine data-gathering systems. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;General Electric strengthened the&#xA;  747-100 airframe to allow it to be capable of flying 747-300 type&#xA;  maneuvers, needed for high - inlet - angle, fan - stress and inlet -&#xA;  stability testing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;GEAE would attach the test engine to the number two&#xA;  engine pylon located on the aircrafts left wing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.air-and-space.com/Boeing%20747-121%20General%20Electric%20Engine%20Testbed.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;air-and-space.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dMqfw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dMqfw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.airliners.net/photo/1330828/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2015-12-18T21:11:42.440" LastActivityDate="2015-12-18T21:11:42.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23776" PostTypeId="2" ParentId="23768" CreationDate="2015-12-18T20:26:11.523" Score="5" Body="&lt;p&gt;Aircraft like to fly near their optimum L/D ratio, where &lt;a href=&quot;https://aviation.stackexchange.com/questions/3670/is-the-maximum-lift-drag-ratio-found-at-minimum-drag&quot;&gt;drag reaches its minimum&lt;/a&gt;. At that speed the drag is split evenly between induced (lift-related) and viscous drag. In a very rough approximation, half of the drag is indeed caused by friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if we look more closely, drag has more sources. Besides friction and induced drag, there is pressure drag due to flow separation at blunt, rear-facing surfaces. More separation could be caused by boundary layer effects, but this is highly aircraft- and angle-of-attack-specific. One could argue that this kind of pressure drag is also caused by friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we now look at specific missions, more differences creep up:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An interceptor will try to reach a specific point in the shortest possible time. Here friction drag will easily be the dominant source of drag, induced drag is small and some of the fuel is needed for acceleration.&lt;/li&gt;&#xA;&lt;li&gt;Airliners fly at optimum transport performance, which is &lt;a href=&quot;https://aviation.stackexchange.com/questions/3612/how-does-wind-affect-the-airspeed-that-i-should-fly-for-maximum-range-in-an-airp/3623#3623&quot;&gt;faster than what optimum L/D would require&lt;/a&gt;. Friction drag here is indeed the biggest source of drag, but contributes maybe 50% to 60%.&lt;/li&gt;&#xA;&lt;li&gt;Observation aircraft which want to optimize flying time will fly slower than what optimum L/D requires, especially if they use propellers. Now induced drag is responsible for the majority of fuel used.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-12-26T20:08:38.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23778" PostTypeId="2" ParentId="23717" CreationDate="2015-12-18T21:34:28.477" Score="2" Body="&lt;p&gt;Nobody can tell you every single operator who might hire you. There are a couple of operators that I personally know have hired low-time pilots, like Merimbula Air Services or Polar Aviation. But what I want to do here is give you some strategies that could help you land your first job:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1) Don't  stop training&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passed the CPL Flight Test? Great! Now do more. Get as many endorsements and ratings as you can - tailwheel, aerobatics, low level etc. Fly as many different types of aircraft as possible, then search for operators who fly those types. And if you can afford it, the holy grail would be to get a MECIR. But a very good-value rating to get is the instructor rating. Needless to say this could get you a job almost anywhere in the country, but it is nevertheless a competitive field. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2) Get schmoozing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aviation industry in Australia is relatively insular. It is often not just what you know, but who you know. Rub shoulders with as many people as you can - not just pilots but engineers, managers too. Don't burn bridges. Any one of these people might one day have a friend who is expanding their operation and they could recommend you. Your instructors could be friends for life - ask them how they have gotten to where they are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3) Consider your  approach&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar to the point above, are you simply sending your CV to random operators? This is often more annoying for them than anything. Pick up the phone (or better yet drop in) for an honest, genuine chat. Even if they haven't advertised, they might have it in the back of their mind that they need another pilot. If you make a good impression the worst that can happen is they will have you in mind next time there is a vacancy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4) Broaden yourself&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this is an aspect of pilot recruitment that is often overlooked. Most operators that would hire you are a small business. You are so much  more valuable to them if you can do more than simply fly a plane. Work on your non-technical skills - get some experience in customer service, HR, office administration, or book keeping. Larger operators in particular need more hands in their regulatory/safety management areas - if you are good at policy implementation or technical writing you could be useful here. By selling your non-piloting strengths, might not be flying full-time but it's a door in to the aviation world, and will certainly help your overall career prospects. As an example, I think there's a great opportunity at the moment with the ATSB to be essentially a junior investigator, and all you need is a CPL. You won't be flying in this job but you'll gain so many experiences relevant to a flying career (plus a handsome salary). If you have training in accident investigation larger operators, especially airlines, will love you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You've picked a difficult profession to crack into, but with patience, persistence and intelligence you'll get there. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2015-12-18T21:34:28.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23779" PostTypeId="2" ParentId="23739" CreationDate="2015-12-18T21:53:40.607" Score="9" Body="&lt;p&gt;A helicopter develops lift by accelerating air downwards through its rotors.  This relies on the air above the rotors being slow enough for the rotors to accelerate that air enough to provide sufficient lift. When hovering in still air, the incoming air has zero velocity relative to the helicopter. While of course the air is conserved, in a large volume of air, the downwash is able to diffuse much more, and much of it does not immediately circulate back up above the helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the helicopter were enclosed in a sphere, the smaller the sphere, the less the air would be able to diffuse. The downwash would circulate back to the top of the sphere, where the rotors would take that air in again. The rotors would be less effective at accelerating the air that is coming in with significant velocity, just as a propeller develops less thrust with increasing forward speed. Successful hover would depend on the helicopter being able to develop lift at a rate of circulation where the air can slow down enough for the rotors to be effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems like a experiment manageable enough that someone could try it at home...&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-12-18T21:53:40.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23780" PostTypeId="1" AcceptedAnswerId="23781" CreationDate="2015-12-18T21:54:52.910" Score="6" ViewCount="252" Body="&lt;p&gt;The FAA is requiring all operators of small unmanned aircraft systems between 0.55 and 55 pounds to register. This is to help ensure that operators of model aircraft and drones act in a responsible manner, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;https://www.faa.gov/news/updates/media/2015-12-13_2120-AK82_RIA.pdf&quot; rel=&quot;noreferrer&quot;&gt;Registration and Marking Requirements for Small Unmanned Aircraft document available from the FAA (PDF)&lt;/a&gt;, there are examples given of drones being flown near wildfires that interrupted firefighting efforts, despite a &lt;code&gt;temporary flight restriction for the area surrounding the fire&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems obvious to me that operating an RC aircraft near a wildfire might not be a good idea. However, &quot;temporary flight restrictions&quot; could exist in other cases that aren't quite so obvious. There is no requirement (as far as I know) for sUAS operators to check NOTAMs, aviation charts, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can an operator be sure they are in compliance in every situation? It seems like it might be very easy to violate some regulation inadvertently.&lt;/p&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2017-10-18T20:45:19.197" Title="How are operators of small UAS craft supposed to know about flight restrictions?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23781" PostTypeId="2" ParentId="23780" CreationDate="2015-12-18T22:06:17.877" Score="8" Body="&lt;p&gt;Information about current and future TFR areas is &lt;a href=&quot;http://tfr.faa.gov/tfr2/list.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;available from the FAA&lt;/a&gt;, even as an &lt;a href=&quot;http://tfr.faa.gov/tfr_map_ims/html/index.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;easy-to-read map&lt;/a&gt;. If someone is planning on flying a manned or unmanned aircraft, that should be on their list of things to check ahead of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as other airspace restrictions, we have a &lt;a href=&quot;https://aviation.stackexchange.com/q/2917/1696&quot;&gt;question detailing the different types of airspace&lt;/a&gt;. It would be worthwhile for a UAS operator to learn enough about reading charts to at least know the airspace in the area where they intend to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another option would be to &lt;a href=&quot;https://aviation.stackexchange.com/q/4950/1696&quot;&gt;attend ground school&lt;/a&gt; or at least do some amount of self-study. Just as pilots need to know how to operate according to the rules of the airspace system, UAS operators could benefit from the education.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2015-12-18T22:15:56.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23782" PostTypeId="2" ParentId="23768" CreationDate="2015-12-18T22:06:46.623" Score="1" Body="&lt;p&gt;That statement simplifies what's really happening to the basics of physics 101. Technically that statement is 100% true. It is also true for cars and ships: your car use most of its fuel to overcome friction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Newton's first law: An object that is in motion stays in motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means that once your car or an aircraft has reached the desired speed you should no longer need to run the engine and the car/aircraft will continue moving at a uniform speed until you apply the brakes. Is this how you drive your car? Obviously not. You need to depress the throttle all the way (or at least most of the way).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what gives? Newton says that the car should continue moving and therefore you should be able to turn off your engine for 99% of your trip! The answer is friction, it all its various forms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some people may say: &quot;but most of the energy in flight is used to generate lift, not overcome friction&quot;. But lift comes from friction. Lift causes drag, specifically induced drag. But this drag is only possible due to friction - the friction of air with itself. We quantify this &quot;friction&quot; as viscosity. Fluids that are completely frictionless have zero viscosity (such things do exist: they're called superfluids) and it's impossible to generate lift in such fluids. Fortunately air is viscous so airplane wings can work in air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So.. technically it's true - any moving vehicle spends the majority of its fuel to overcome friction. But it's not really useful from an engineering perspective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an exception though: spaceships. Since friction is almost zero in the vacuum of space spaceships burn their fuel only at the beginning of the trip and at the end to slow down. 99% of the time the engines on a spaceship is turned off and the ship merely coast along thanks to Newton's first law.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2015-12-18T22:06:46.623" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23783" PostTypeId="2" ParentId="23747" CreationDate="2015-12-18T22:27:04.977" Score="4" Body="&lt;h2&gt;Local air temperature&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In fast aircraft, the maximum heating is at the stagnation point. Here the kinetic energy of the flow is completely converted into pressure, which heats the air and, consequently, the structure. Due to the low local speed and the high pressure at and near the stagnation point, the rate of heat transfer is high, too, adding to the heat load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The formula for the stagnation point temperature $T_s$ of an ideal gas of the temperature $T_{\infty}$ hitting an object with the Mach number Ma is $$T_s = T_{\infty} + T_{\infty}\cdot\frac{(\kappa-1)\cdot Ma^2}{2}$$&#xA;For air the ratio of specific heats $\kappa$ is 1.4. The tip of the fuselage nose of an airliner flying at Mach 0.85 will see air temperature to rise by 14.45%. If the air at altitude has a temperature of 220°K (-53.15°C), the air temperature at the stagnation point will be 251.8°K (-21.36°C).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But past the stagnation point the air will accelerate and become faster than flight speed. Now pressure and, consequently, temperature need to drop sufficiently to encourage the flow to stay attached and follow the curvature of the forward fuselage. This acceleration will cool the air, so the flow right above the windshield will be &lt;strong&gt;cooler&lt;/strong&gt; than the ambient air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along the cylindrical portion of the fuselage, we find roughly flight speed again, but now friction will change the temperature close to the wall. Again the kinetic energy is converted, but the heating is caused by friction. See the boundary layer plots below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LSEeL.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LSEeL.png&quot; alt=&quot;Frictional and thermal boundary layer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Frictional and thermal boundary layer (picture &lt;a href=&quot;http://me-lrt.de/warme-stoff-transport-grenzschichten-temperatur-geschwindigkeit&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature close to the wall is now called &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerodynamic_heating&quot; rel=&quot;nofollow noreferrer&quot;&gt;recovery temperature&lt;/a&gt; and is different from the stagnation point temperature because there is a small speed component normal to the surface which carries away some of the heat. The air temperature depends on the ratio between viscous diffusion and thermal diffusion, which is expressed by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Prandtl_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Prandtl number Pr&lt;/a&gt;. If Pr&gt;1, the air temperature at the wall is higher than the stagnation temperature and for Pr&amp;lt;1, it is colder. The Prandtl number of air is 0.72, so the air surrounding the fuselage is slightly colder than the stagnation temperature.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fuselage temperature&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The fuselage temperature is determined by the equilibrium between &lt;a href=&quot;https://en.wikipedia.org/wiki/Thermal_conductivity&quot; rel=&quot;nofollow noreferrer&quot;&gt;thermal conductivity&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Radiative_cooling&quot; rel=&quot;nofollow noreferrer&quot;&gt;radiation&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Convection&quot; rel=&quot;nofollow noreferrer&quot;&gt;convection&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Conductivity:&lt;/strong&gt; Here it is important how much the internal temperature of the fuselage can heat the skin. Cabin temperature is likely around 20°C, so some heating can be expected. However, since most airliners have isolation mats between the outer skin and the internal wall panels, conductivity from the inside is not dominant and will likely raise the skin temperature by a few degrees or less. The low heat conductivity of air (&lt;a href=&quot;http://www.engineeringtoolbox.com/air-properties-d_156.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.0204 W per m² and Kelvin&lt;/a&gt;) means that the heating from the inside dominates conductivity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Radiation:&lt;/strong&gt; Since the top of the fuselage is pointing into space, its far-field radiation budget is negative at night and where it points away from the sun, so radiation will cool it. The lower fuselage, however, is facing either the ground or clouds below, which both are likely hotter than the ambient air. Radiation will not cool it much and is more likely to heat it up. The part of the fuselage in direct sunlight will be significantly hotter again, depending on its color.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Convection:&lt;/strong&gt; This is the dominant factor due to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Forced_convection&quot; rel=&quot;nofollow noreferrer&quot;&gt;high speed&lt;/a&gt; of the air around the fuselage. Here the air and the fuselage exchange heat by near-field radiation, and since the layer of air is replenished quickly and continuously, the air temperature is impressed on the fuselage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I did not go to the effort of calculating the end result, but tried to list the main contributors and their magnitude. In general, the fuselage temperature is slightly below the stagnation temperature, and a dark fuselage in bright sunlight or one with little insulation and a hot interior will be several degrees hotter than the stagnation temperature.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-18T22:27:04.977" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23784" PostTypeId="1" AcceptedAnswerId="23789" CreationDate="2015-12-18T22:37:44.913" Score="7" ViewCount="3531" Body="&lt;p&gt;AC 00-6A (Aviation Weather) Chapter 11 states:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Do's and Don'ts of Thunderstorm Flying&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;To avoid the most critical icing, establish&#xA;a penetration altitude below the freezing&#xA;level or above the level of -15 C.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I'm trying to understand how flying above an altitude where -15 degrees Celsius occurs would help me avoid icing. I'm also trying to understand how flying below the freezing level would help me avoid icing. What is the explanation?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-18T23:12:22.817" Title="How does flying below the freezing level in a thunderstorm help avoid the most critical icing?" Tags="&lt;weather&gt;&lt;icing&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23785" PostTypeId="1" CreationDate="2015-12-18T22:52:20.503" Score="10" ViewCount="819" Body="&lt;p&gt;In the USA airport facilities directory (AFD), some towers (eg KSJC) are listed with the note:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Emerg frequency 121.5 not avbl at tower.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why do these facilities not monitor guard? Does the note actually mean that they cannot even talk on 121.5 in an emergency?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am assuming it is because a different facility in the area (eg a TRACON) is monitoring guard, and they don’t want two facilities taking responsibility for guard. But suppose an airplane is landing in an emergency, does that mean the tower couldn’t even listen to the emergency communications?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does this work practically in emergencies?&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2015-12-24T18:11:58.737" Title="Why do some airport towers avoid monitoring 121.5?" Tags="&lt;air-traffic-control&gt;&lt;radio&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23786" PostTypeId="2" ParentId="23784" CreationDate="2015-12-18T22:59:18.747" Score="10" Body="&lt;p&gt;Temperature &lt;em&gt;decreases&lt;/em&gt; with &lt;em&gt;increasing&lt;/em&gt; altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The “freezing level” apparently means level, or &lt;em&gt;altitude&lt;/em&gt;, where the temperature equals freezing point. Therefore below it, temperature is higher than freezing point and so no freezing occurs (though keep in mind that temperature above the wing is slightly lower than ambient due to adiabatic cooling, so icing actually starts at temperature slightly above 0°C).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to explain the altitude above -15°C we need to mention that icing occurs when the atmosphere contains “supercooled” water droplets that are still liquid at temperatures below freezing that can freeze when they come in contact with the aircraft. But at temperatures below -15°C most droplets have already frozen into tiny ice pellets. Since those won't stick to the aircraft, icing decreases again when it's too cold. &lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2015-12-18T22:59:18.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23787" PostTypeId="2" ParentId="23784" CreationDate="2015-12-18T23:03:26.417" Score="4" Body="&lt;p&gt;Icing on aircraft relies on liquid water hitting the airplane and freezing onto its surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The typical outside air temperature range for ice formation is from &lt;a href=&quot;https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=33&amp;amp;sID=152&amp;amp;preview=true&quot; rel=&quot;nofollow&quot;&gt;-20 °C to 2 °C&lt;/a&gt;. Water in the atmosphere can become supercooled to below 0 °C, and then freeze into ice upon contact with the aircraft. Below -15 or -20 °C, the water is much more likely &lt;a href=&quot;https://en.wikipedia.org/wiki/Atmospheric_icing&quot; rel=&quot;nofollow&quot;&gt;to have frozen into ice particles&lt;/a&gt;, which do not accumulate as ice would. This is why the colder temperatures will prevent further ice formation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the temperature is above 2 °C, it will not be supercooled. While it's possible that the water could freeze to a cold surface, the wing will typically not remain significantly colder than the surrounding air.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2015-12-18T23:03:26.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23788" PostTypeId="2" ParentId="23573" CreationDate="2015-12-18T23:07:05.693" Score="4" Body="&lt;p&gt;&lt;a href=&quot;http://www.hoppes.com/bore-cleaners/no-9-solvent&quot; rel=&quot;nofollow&quot;&gt;Hoppes No. 9&lt;/a&gt; is often used for cleaning aircraft fuel injection nozzles in general. This solvent is widely available for cleaning firearms. The cleaning procedure typically involves submerging the detached nozzles in the solvent for as long as necessary, typically 10-60 minutes depending on the level of fouling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: I don't have any specific maintenance data on your nozzles, so you may want be wary of the applicability of the information I offer.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-04T23:29:53.120" LastActivityDate="2016-03-04T23:29:53.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23789" PostTypeId="2" ParentId="23784" CreationDate="2015-12-18T23:12:22.817" Score="11" Body="&lt;p&gt;The icing occurs due to the presence of supercooled liquid droplets. From &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/22268&quot;&gt;FAA AC on Icing&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The condition most favorable for very hazardous icing is the presence of many large, supercooled water drops.... Thus, heaviest icing usually will be found at or slightly above the freezing level where temperature is never more than a few degrees below freezing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For ice to form on the aircraft, the following conditions are required:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The presence of liquid water i.e. rain or cloud droplets.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The temperature at aircraft structure should be at or below freezing point.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, as the altitude increases, temperature decreases. Using this, the best way to avoid these conditions would be to either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Fly above the altitude where the temperature is &lt;em&gt;below&lt;/em&gt; -15 degrees, where supercooled water drops are not present (they would've frozen already), or&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fly below the altitude where the temperature is &lt;em&gt;above&lt;/em&gt; freezing point, where the water droplets, if present are not supercooled.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-18T23:12:22.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23790" PostTypeId="2" ParentId="23768" CreationDate="2015-12-18T23:27:46.053" Score="10" Body="&lt;p&gt;No, the majority of the fuel is wasted on inefficiency of the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Internal combustion engines like turbine engines are not exactly energy efficient. Most of the fuel is wasted by running the engine. Only about 35% to 40% of the energy from the fuel is converted to propulsive energy.  The rest of the energy from the fuel (~ 65%) is lost on heating up the atmosphere directly, excess kinetic energy in the exhaust stream, internal drag &amp;amp; friction of the engine and producing noise.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The remaining ~35% the energy is there to overcome the work done by drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This drag can be split into lift induced drag and parasitic drag. &#xA;It can also be split into pressure drag and friction drag. &#xA;For simplicity assume that all the lift induced drag is all pressure drag, and all parasitic drag is friction drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft usually cruise near the speed where drag is lowest. In such a situation, 50% of the drag is induced drag and 50% is parasitic drag. In practice cruise speed is a bit above the minimum drag speed, so the parasitic drag exceeds the induced drag. If our earlier assumption is correct, then over 50% of the drag would be friction drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That would bring the total estimates to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;65% wasted&lt;/li&gt;&#xA;&lt;li&gt;20% friction drag&lt;/li&gt;&#xA;&lt;li&gt;15% pressure drag&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For example the GE90, the engine fitted on most Boeing 777s, produces a thrust of 70 kN in cruise flight of 250 m/s at a fuel consumption of 1.08 kg/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propulsive power delivered by the engine is $70 \cdot 10^3 \cdot 250 = 17.5\cdot 10^6 \textrm{W}$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet fuel has a specific heat of $43.15 \cdot 10^6 \textrm{J/kg}$&#xA;The energy consumption of the engines is thus:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$1.08 \cdot 43.15 \cdot 10^6 = 46.6 \cdot10^6\textrm{W}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That gives an efficiency of 37.6%. This may seem poor but it is one of the most efficient engines available today. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://web.stanford.edu/~cantwell/AA283_Course_Material/GE90_Engine_Data.pdf&quot; rel=&quot;noreferrer&quot;&gt;Data source&lt;sup&gt;PDF&lt;/sup&gt;&lt;/a&gt; for thrust, speed &amp;amp; consumption: &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-12-25T21:10:39.340" LastActivityDate="2015-12-25T21:10:39.340" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23791" PostTypeId="2" ParentId="23760" CreationDate="2015-12-19T01:52:42.207" Score="11" Body="&lt;p&gt;I'd like to answer with a focus on the SR-71, since I happen to have a book that gives details on its design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ben Rich was the lead of the propulsion and thermodynamics group for the SR-71, and Kelly Johnson's successor as head of the Skunkworks for later programs.  In the &quot;Faster Than a Speeding Bullet&quot; chapter of his memoir &lt;em&gt;Skunkworks&lt;/em&gt; (pg 203 in the first paperback edition, 1994), he writes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...&#xA;  I volunteered some unsolicited advice about how we could use a softer titanium that began to lose its strength at 550 degrees.  My idea was to paint the airplane black.  From my college days I remembered that a good heat absorber was also a good heat emitter and would actually radiate away more heat than it would absorb through friction.  I calculated that black paint would lower the wing temperatures 35 degrees by radiation.  But Kelly [Johnson, head of Skunkworks and the then-A12 project] snorted impatiently and shook his head...&#xA;  Overnight, however, he apparently had second thoughts...&quot;On the black paint,&quot; he said, &quot;you were right about the advantages and I was wrong.&quot;  He handed me a quarter.  It was a rare win.  So Kelly approved my idea of painting the airplane black, and by the time our first prototype rolled out the airplane became known as the Blackbird.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The chapter goes on into greater detail on various unique material selections:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;stainless steel hydraulic lines&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Hastelloy X ejector flaps&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Elgiloy control cables&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Gold-plated plumbing lines&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Titanium screws and rivets&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Special rubber for the landing gear wheels, which were then inflated with nitrogen&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet fuel with a higher flash point (JP-7)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Pg 205:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The fuel acted as an internal coolant.  All the heat built up inside the aircraft was transferred to the fuel by heat exchangers.  We designed a smart valve -- a special valve that could sense temperature changes -- to supply only the hottest fuel to the engines and keep the cooler fuel to cool the retracted landing gear and avionics.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pg 207:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We designed the cockpit air-conditioning to bleed air off the engine compressor and dump it through a fuel air cooler, then through an expansion turbine, into the cabin at a frigid minus 40 degrees F, which lowered the ovenlike 200-degree cockpit to a balmy Southern California beach day.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I guess there's three generic design principles embodied here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;selection of materials to withstand high temperatures&lt;/li&gt;&#xA;&lt;li&gt;rejection of as much heat as possible--here by radiation from the aircraft's surface and convection out the engine exhaust via the fuel &lt;/li&gt;&#xA;&lt;li&gt;sequestration of heat away from critical areas, as much as possible&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3146" LastEditorUserId="3146" LastEditDate="2016-11-19T01:03:47.463" LastActivityDate="2016-11-19T01:03:47.463" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23792" PostTypeId="1" AcceptedAnswerId="23827" CreationDate="2015-12-19T08:27:13.297" Score="4" ViewCount="397" Body="&lt;p&gt;Suppose we are in HDG mode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Trivially, we may visually judge which leg we on the victor airway and activate that leg. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in real-world, I found sometimes the fixes are so close and the airplane is relatively far from the airways. It is difficult to tell exactly which leg I am going to intercept, without &quot;ruler&quot; assistance. Meanwhile, ATC may change HDG assignments, and therefore the intercepted leg may change. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a way to &quot;activate the nearest leg and intercept&quot; in G1000? or how would you solve this problem other ways? &lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2015-12-20T23:05:57.860" Title="In G1000, how can I intercept a victor airway with multiple legs?" Tags="&lt;autopilot&gt;&lt;fms&gt;&lt;g1000&gt;&lt;flight-director&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23793" PostTypeId="1" AcceptedAnswerId="23795" CreationDate="2015-12-19T10:02:43.820" Score="8" ViewCount="5166" Body="&lt;p&gt;Many sources on the internet say flares are carried in the fuselage, but do not specify the exact location of the compartment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anybody know exactly where they are stored?&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="1467" LastEditDate="2017-12-14T08:43:08.823" LastActivityDate="2017-12-14T08:43:08.823" Title="Where do military aircraft carry flares?" Tags="&lt;military&gt;&lt;fighter&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23794" PostTypeId="1" CreationDate="2015-12-19T10:43:30.380" Score="4" ViewCount="383" Body="&lt;p&gt;Let us say you're in a non-fly-by-wire tactical aircraft (say a F-15 or an A-4) doing maneuvers in the local MOA, and you manage to depart the jet in some non-spin fashion.  Is there a standard procedure for recovering the jet to controlled flight, analogous to how there are standard spin recovery procedures, or is the first step on the checklist &quot;eject&quot;?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2015-12-19T21:37:00.950" Title="Is there a universal departure recovery procedure?" Tags="&lt;military&gt;&lt;emergency&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23795" PostTypeId="2" ParentId="23793" CreationDate="2015-12-19T10:49:28.763" Score="13" Body="&lt;p&gt;The location of the flare/chaff dispenser (FCD) depends on the aircraft type and even in case of the same aircraft, they can be located in different place, depending on the version and customer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the F-16 carries the FCD in its body fairing, as can be seen in the following image of Hellenic Air Force F-16 Demo Team “Zeus”.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uh1V0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uh1V0.jpg&quot; alt=&quot;F-16 catridge&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://theaviationist.com&quot; rel=&quot;noreferrer&quot;&gt;theaviationist.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows a close view of FCD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cvAv7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cvAv7.jpg&quot; alt=&quot;F-16 flare&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://f-16.net&quot; rel=&quot;noreferrer&quot;&gt;f-16.net&lt;/a&gt;, credited to Capt. Lance&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows an Israeli F-16B 'Nezt' having FCD between its ventral fins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VAxXB.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VAxXB.png&quot; alt=&quot;F-16 FCD 1&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://theaviationist.com&quot; rel=&quot;noreferrer&quot;&gt;theaviationist.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Initially, most of the FCDs were retrofitted to the existing aircraft and were simply attached to them. However, most of the modern aircraft have FCD bays integrated into their fuselage. Still, some aircraft can carry extra flares/chaffs in their pylons (called PIDS (Pylon Integrated Dispenser System)), as shown below in an RDAF aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kDs4u.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kDs4u.jpg&quot; alt=&quot;PIDS&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://f-16.net&quot; rel=&quot;noreferrer&quot;&gt;f-16.net&lt;/a&gt;, credited to Erik Frikke&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Also, most of the combat aircraft have the FCD in the bottom, while transport aircraft (and helicopters) have them on their sides.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2171" LastEditDate="2015-12-20T14:01:50.097" LastActivityDate="2015-12-20T14:01:50.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23796" PostTypeId="1" CreationDate="2015-12-19T12:46:23.280" Score="7" ViewCount="162" Body="&lt;p&gt;What parameters are considered in estimating the weight of an aircraft in the beginning of the design process?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="946" LastEditDate="2015-12-20T12:31:54.700" LastActivityDate="2015-12-20T12:31:54.700" Title="During the early design stages, what parameters are considered in determining the weight of an aircraft?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23797" PostTypeId="1" CreationDate="2015-12-19T13:04:25.430" Score="0" ViewCount="135" Body="&lt;p&gt;While designing an aircraft and analyzing it using simulation software, one result comes out. Is what occurs on the aircraft in reality similar to the result as given in a simulation?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="19" LastEditDate="2015-12-23T23:46:17.923" LastActivityDate="2015-12-24T13:48:06.427" Title="Is there similar result between simulation and reality?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-12-26T22:17:13.697" ContentLicense="CC BY-SA 3.0" />
  <row Id="23798" PostTypeId="2" ParentId="23796" CreationDate="2015-12-19T13:46:20.100" Score="0" Body="&lt;p&gt;When designing, the designers have to take into account:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The amount and type of materials used on the airframe. Many aircraft made nowadays use composite materials because they are stronger and lighter than metals. The engines also play a significant role in this because they have to create a certain amount of thrust without adding too much weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They also have to take into account the payload that (amount of fuel, passengers, and/or cargo or other things) that the aircraft will carry.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-19T15:54:31.853" LastActivityDate="2015-12-19T15:54:31.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23799" PostTypeId="1" CreationDate="2015-12-19T15:38:36.270" Score="1" ViewCount="2041" Body="&lt;p&gt;I understand that there are noise issues, and that there may be an economic case dependent on stage length, but other than that I'm not quite sure why they haven't happened. Is there something technical I'm missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exhaust gas re-ingestion doesn't seem to be that great an issue, it looks like you just install fences to make sure that exhaust can't get into the inlets.&lt;/p&gt;&#xA;" OwnerUserId="12726" LastActivityDate="2015-12-19T16:54:56.140" Title="What are the reasons why we do not have VTOL commercial airliners?" Tags="&lt;airlines&gt;&lt;vtol&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2015-12-19T18:32:22.330" ContentLicense="CC BY-SA 3.0" />
  <row Id="23800" PostTypeId="2" ParentId="23799" CreationDate="2015-12-19T15:58:49.057" Score="0" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Commercial airliners are significantly larger, and therefore heavier, than aircraft with use V/STOL. Because of that, it would take more fuel and engine power to run that airplane, driving up the cost of running it. There are also many other airframe stress and balance factors that come into play when doing VTOL.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you are including turbo-prop airliners in your definition of airliners, they could do V/STOL with a configuration like the V-22 Osprey because they are small enough.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-12-19T15:58:49.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23801" PostTypeId="1" AcceptedAnswerId="23808" CreationDate="2015-12-19T16:15:17.117" Score="39" ViewCount="4374" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_space_shuttle_landing_sites#Transoceanic_Abort_Landing_Sites&quot; rel=&quot;noreferrer&quot;&gt;Some of the STS backup landing sites&lt;/a&gt; were in Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, The STS would actually have to fly there only in case of extreme emergency, so the number one priority was just to save the lives of the crew members.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, did NASA have a plan, or would it be doable to airlift the Space Shuttle atop an the Shuttle Carrier Aircraft like on this picture?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8RYmH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8RYmH.jpg&quot; alt=&quot;Shuttle Carrier Aircraft transporting a Space Shuttle orbitere&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm especially curious about the range penalty induced by the additional drag of piggybacking the orbiter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Picture credits: NASA / Carla Thomas, Public domain.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="4105" LastEditDate="2015-12-21T12:25:12.233" LastActivityDate="2019-10-24T10:34:16.183" Title="Could the Shuttle Carrier Aircraft do a transatlantic flight with a Space Shuttle orbiter on its back?" Tags="&lt;drag&gt;&lt;range&gt;&lt;transatlantic&gt;&lt;transport-category&gt;&lt;space-shuttle&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23802" PostTypeId="2" ParentId="23794" CreationDate="2015-12-19T16:30:01.563" Score="3" Body="&lt;p&gt;Ok, I think I have enough to answer this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=_P7B9TuvYUk&quot; rel=&quot;nofollow&quot;&gt;Here is an older training video&lt;/a&gt; I found on YouTube for ejection decisions. It looks like it has an aircraft from the A-10 &quot;Family&quot; of aircraft in it (I didn't watch the entire video, but looks like an older variant).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That all being said, a departure is not an automatic &quot;eject&quot; in any aircraft. Departure from controlled flight unless the aircraft is damaged or at a low altitude is typically recoverable, save for a few aircraft that cannot recover from certain departures (flat spins in some types for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I said in my comment, there is no &quot;universal procedure&quot; for recovery. The recovery procedure differs depending on your flight attitude. Speaking from a GA perspective (but I assume it can somewhat be applied to military), recovering from a stall involves stick forward and power in, whereas recovering from a spin involves stick forward and power out (and other things). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most &quot;universal&quot; method I can think of is to just let the airplane fly itself out. Airplanes (as I stated) are inherently stable in flight and provided you have the altitude and control surfaces have the authority, many types of departures will simply stabilize out and recover in time. Think of pilots in high-G maneuvers, even with G-Suits can sometimes black out (or red-out) for short periods. This is experienced quite a bit during some departures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example of a pilot getting over anxious and bugging out is the &lt;a href=&quot;https://www.youtube.com/watch?feature=player_embedded&amp;amp;v=3M2XZEYqIpQ&quot; rel=&quot;nofollow&quot;&gt;Cornfield Bomber Incident&lt;/a&gt; where the aircraft recovered after the pilot ejected and continued flying into a field (and even ran along the ground for a long period of time afterwards). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to answer the question, the &quot;first item&quot; on the checklist is not &quot;eject&quot;. I assume it would be a very short military (and flying) career for the pilot who ejected from a recoverable/flyable aircraft. Ejection seats are extremely effective &lt;a href=&quot;https://www.youtube.com/watch?v=5MQk1yvsoKY&quot; rel=&quot;nofollow&quot;&gt;even at low altitudes&lt;/a&gt; and pilots typically fly aircraft &lt;a href=&quot;https://www.youtube.com/watch?v=M359poNjvVA&quot; rel=&quot;nofollow&quot;&gt;until they won't fly anymore, even if it only has one wing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-19T16:49:13.820" LastActivityDate="2015-12-19T16:49:13.820" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23803" PostTypeId="2" ParentId="23801" CreationDate="2015-12-19T16:30:08.643" Score="8" Body="&lt;p&gt;Apparently Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From NASA document &lt;a href=&quot;http://www.nasa.gov/centers/kennedy/pdf/167472main_TALsites-06.pdf&quot;&gt;Space Shuttle Transoceanic&#xA;Abort Landing (TAL) Sites&lt;/a&gt;(emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Payloads and/or airborne support equipment will remain onboard the &lt;strong&gt;orbiter for the flight back to Kennedy Space Center&lt;/strong&gt; unless the capability of the shuttle carrier aircraft, landing site location or other requirements dictate otherwise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The document also details the procedure to be followed in case the TAL is to be used. TAL sites were 'activated' prior to launch and a C-130 was kept on standby for evacuation and emergencies.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-19T16:30:08.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23804" PostTypeId="2" ParentId="23801" CreationDate="2015-12-19T16:30:15.863" Score="28" Body="&lt;p&gt;Yes, it was possible and NASA had a plan. &lt;a href=&quot;https://en.wikipedia.org/wiki/Space_Shuttle_Enterprise&quot;&gt;Enterprise&lt;/a&gt; was taken on a &lt;a href=&quot;http://londonist.com/2010/03/the_day_the_space_shuttle_came_to_l&quot;&gt;European tour&lt;/a&gt; in 1983, visiting the UK, France, Germany and Italy. To get there, it crossed the Atlantic on the back of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Carrier_Aircraft&quot;&gt;Shuttle Carrier Aircraft&lt;/a&gt; (the converted 747).  According to &lt;a href=&quot;http://primary.slate.com/articles/news_and_politics/explainer/2005/08/how_does_the_space_shuttle_fly_home.html&quot;&gt;Slate&lt;/a&gt;, the range of the SCA was about 1,000 nautical miles so it made refuelling stops at Goose Bay and Keflavik on its way to London Stansted.&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2015-12-20T07:27:54.513" LastActivityDate="2015-12-20T07:27:54.513" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23805" PostTypeId="1" AcceptedAnswerId="23838" CreationDate="2015-12-19T16:53:50.080" Score="11" ViewCount="3956" Body="&lt;p&gt;A trip I took led me to wonder how airports/airlines decide when to allocate a gate and when to board out on the apron.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yesterday, I flew TLV-IST-BOS on Turkish Airlines. At the start of the trip, I briefly wondered if we were travelling to Istanbul (IST) by bus. The airplane was parked far from the gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We got to IST, and, once more to ride the bus. In this case, we parked at jetway, but we were sent down the stairs and onto a bus. Turkish sure is a big, legacy airline at IST.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, to complete the process, our A340 for Boston was parked half-way to Europe, and reached by a bus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What determines all this? Bad luck? Plane size?&lt;/p&gt;&#xA;" OwnerUserId="9238" LastEditorUserId="19" LastEditDate="2015-12-21T13:30:44.493" LastActivityDate="2019-05-04T23:06:26.533" Title="Who decides whether an airline docks at a jetbridge or parks at a remote stand?" Tags="&lt;airport&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23806" PostTypeId="2" ParentId="23799" CreationDate="2015-12-19T16:54:56.140" Score="0" Body="&lt;p&gt;First, we have to decide what kind of VTOL we are going to use- tiltrotor like &lt;a href=&quot;https://en.wikipedia.org/wiki/AgustaWestland_AW609&quot; rel=&quot;nofollow noreferrer&quot;&gt;Augusta WestlandAW609&lt;/a&gt;, compound helicopters like &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurocopter_X3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurocopter X3&lt;/a&gt; or using jets like the F-35. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For commercial operations, the first two are not very suitable as they lack the speed and carrying capacity. At best, they can act as costly and complicated propeller aircraft, which are not the main type in use. So, lets consider the jet aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, there was a vertical takeoff jet transport, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_31&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dornier Do 31&lt;/a&gt;. It is instructive to consider what happened in this case. It never got past the prototype stage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AlwC9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AlwC9.jpg&quot; alt=&quot;Do 31&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Dornier_Do_31_in_1968.jpg#/media/File:Dornier_Do_31_in_1968.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dornier Do 31 in 1968&lt;/a&gt;&quot; by Ralf Manteufel - &lt;a href=&quot;http://www.airliners.net/photo/Germany---Air/Dornier-Do-31E/1265410/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airliners.net/photo/Germany---Air/Dornier-Do-31E/1265410/L/&lt;/a&gt;. Licensed under GFDL 1.2 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;For takeoff, the VTOL aircraft has to produce quite a large amount of thrust- Do 31 used a grand total of 10 engines, including 8 &lt;em&gt;exclusively&lt;/em&gt; for vertical takeoff. The engines produced a total thrust in excess of 290kN for lifting the 27 ton aircraft (not at its MTOW). In contrast, the 50 ton Boeing 737-100 had engines that produced a sum total of 128 kN.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even military VTOL aircraft like the Harrier and F-35 were not able to take off vertically at their full load. In fact, Harrier was rarely used operationally in VTOL mode. In most of the cases, it was operated in a rolling takeoff.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;VTOL mechanisms are complicated. You've to either swivel the engine thrust (like F-35) or use separate engine(s) (like Do 31) for vertical takeoff. In either case, you're having dead weight. This increases the fuel and structure required (for support), which leads to further weight and fuel requiremetn and so on.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The fuel consumption for VTOL would be enormous. The economics is against the operation of VTOL aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;More complicated the mechanism is, more chances of failure. Not a good thing in commercial operations.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As for compound helicopter, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairey_Rotodyne&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fairey Rotodyne&lt;/a&gt; was designed with commercial transport in mind; however, noise considerations (among others) killed the project. Of course, if a large rotor is used, the drag will be prohibitive at high speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KGKgF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KGKgF.jpg&quot; alt=&quot;Rotodyne&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from jefflewis.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AW 609 was the first tilt rotor to be developed with commercial operations in mind. However, with the &lt;a href=&quot;http://www.ainonline.com/aviation-news/business-aviation/2015-11-09/aw609-crashed-during-high-speed-testing&quot; rel=&quot;nofollow noreferrer&quot;&gt;fatal crash of second prototype&lt;/a&gt;, it remains to be seen if it will succeed.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-19T16:54:56.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23807" PostTypeId="2" ParentId="23796" CreationDate="2015-12-19T16:55:34.097" Score="8" Body="&lt;p&gt;Any design starts with a mission profile. As a design engineer, you get the payload, range and speed, and maybe constraints like the maximum runway, and then have to come up with a configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that in hand, you look what others have achieved before. There are collections of weight data for different designs and their parts, and formulas which combine the main parameters in a way that the weights line up more or less nicely when plotted over the result of this equation. Plug in your new design's number, and you get something wich will be within ±10% of what is realistic. This is called &lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/M96SC08.pdf&quot;&gt;parametric weight estimation&lt;/a&gt; (PDF!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you can only consider what you have, you start with the boundaries of the sizing mission:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Payload&lt;/li&gt;&#xA;&lt;li&gt;Range or endurance&lt;/li&gt;&#xA;&lt;li&gt;Desired cruise speed and altitude&lt;/li&gt;&#xA;&lt;li&gt;Operational constraints like runway length, operation from unprepared fields, threat scenario.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@Peter is right: Cost per kilo of airframe and per seat-mile (where applicable) is also a starting requirement, and cost minimization is taken care of by designing the smallest possible airframe which can satisfy all requirements while using proven technology. And parametric sizing only works when based on proven technology.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-20T09:07:07.237" LastActivityDate="2015-12-20T09:07:07.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23808" PostTypeId="2" ParentId="23801" CreationDate="2015-12-19T18:13:01.430" Score="41" Body="&lt;h3&gt;Short Answer&lt;/h3&gt;&#xA;&lt;p&gt;A procedure had been established to return from a Transoceanic Abort Landing (TAL) site to the Kennedy Space Center (KSC) using the Shuttle Carrier Aircraft (SCA). The maximum weight that could be ferried from Europe was approx. 87,000 kg, so so weight had to be removed from the orbiter prior to being mated.&lt;/p&gt;&#xA;&lt;p&gt;The SCA had a maximum range, unmated, of 5,500 nautical miles, however when matted the range decreased to 1,000 nautical miles, using reserves. 4,500 NM were lost by carrying the orbiter. The SCA would have had to stop in UK, Iceland, Greenland, and Canada.&lt;/p&gt;&#xA;&lt;p&gt;A test for in-flight refueling had been conducted but no solution was developed. From our friends at &lt;a href=&quot;https://space.stackexchange.com/a/27558/7017&quot;&gt;Space Exploration&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Studies were conducted to equip the SCA with aerial refueling&#xA;equipment, a modification already made to the U.S. Air Force E-4&#xA;(modified 747-200s) and 747 tanker transports for the IIAF. However,&#xA;during formation flying with a tanker aircraft to test refueling&#xA;approaches, minor cracks were spotted on the tailfin of N905NA. While&#xA;these were not likely to have been caused by the test flights, it was&#xA;felt that there was no sense taking unnecessary risks. Since there was&#xA;no urgent need to provide an aerial refueling capacity, the tests were&#xA;suspended.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A &lt;a href=&quot;https://www.nasa.gov/images/content/125475main_mdm_nosecone-lg.jpg&quot; rel=&quot;noreferrer&quot;&gt;tailcone&lt;/a&gt; covering the 3 aft engines and the thrusters was used to reduce the drag and the buffeting on the SCA vertical stabilizers. It also protected the engine nozzles from being damaged in flight.&lt;/p&gt;&#xA;&lt;p&gt;See below if you are interested by more details of the recovery plan.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Plan Used After Landing at the TAL Site&lt;/h3&gt;&#xA;&lt;p&gt;Operations to be conducted to return the orbiter to KSC were documented in a plan that couldn't be identified with certainty, however the US Department of Defense (DOD) plan to support the turnaround is quite descriptive of the operations. From &lt;a href=&quot;http://vandenbergfire.us/main/VFD%20Web%20Additions/New%20SOP%27s/Shuttle/Contingency%20Shuttle%20Landing/Plans/DDMS%20Plans/3611-03%20.doc&quot; rel=&quot;noreferrer&quot;&gt;DDMS TURNAROUND FUNCPLAN 3611-03&lt;/a&gt; (C=TAL day):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The turnaround operation, to include redeployment of&#xA;personnel and equipment, may require up to 120 days to complete. [...]&lt;/p&gt;&#xA;&lt;p&gt;C+18: JTF-DDMS staff coordinates with NASA for ferry flight route&#xA;support.&lt;/p&gt;&#xA;&lt;p&gt;C+22: JTF-DDMS staff presents initial ferry flight support plan to NASA management.&lt;/p&gt;&#xA;&lt;p&gt;C+26: NASA begins 24 hour turnaround operations to prepare and&#xA;mate the orbiter to the SCA for return ferry flight. [...]&lt;/p&gt;&#xA;&lt;p&gt;C+53: Pathfinder and SCA arrive at landing site.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Slides explaining the DOD plan &lt;a href=&quot;http://vandenbergfire.us/main/VFD%20Web%20Additions/New%20SOP%27s/Shuttle/Contingency%20Shuttle%20Landing/Briefings/Return%20to%20Cape.ppt&quot; rel=&quot;noreferrer&quot;&gt;are also available&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;TAL Site Operations&lt;/h3&gt;&#xA;&lt;p&gt;Each of the TAL site was equipped for the Orbiter landing and turnaround operations:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Navigation and landing aids&lt;/li&gt;&#xA;&lt;li&gt;Weather equipment&lt;/li&gt;&#xA;&lt;li&gt;Dedicated ground-support equipment&lt;/li&gt;&#xA;&lt;li&gt;Emergency equipment&lt;/li&gt;&#xA;&lt;li&gt;C-130 aircraft support&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.nasa.gov/centers/kennedy/pdf/167472main_TALsites-06.pdf&quot; rel=&quot;noreferrer&quot;&gt;Nasa Fact - Space Shuttle Transoceanic Abort Landing Sites&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Each TAL site is covered by a separate international agreement. The&#xA;TAL sites are referred to as augmented sites because they are equipped&#xA;with space shuttle-unique landing aids and are staffed with NASA,&#xA;contractor and Department of Defense personnel during a launch and&#xA;contingency landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gt0MT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gt0MT.jpg&quot; alt=&quot;Shuttle's Microwave Landing System&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Shuttle's Microwave Landing System (&lt;a href=&quot;http://www.nasa.gov/mission_pages/shuttle/flyout/microwave_landing_system.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;In addition:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Safing and deservicing of the orbiter would be initiated by the&#xA;deployed TAL team and augmented by a team known as the Rapid Response&#xA;Team. [...]&lt;/p&gt;&#xA;&lt;p&gt;The TAL site ground operations manager would initially be in charge&#xA;until relieved by a higher-ranking management official who would&#xA;arrive on the response/investigation team aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Within 24 hours, the response/investigation teams would arrive at the&#xA;TAL site aboard C-17 aircraft carrying personnel and equipment.  Most&#xA;of the equipment would come from Kennedy Space Center and Dryden&#xA;Flight Research Center in California.&lt;/p&gt;&#xA;&lt;p&gt;Following the advance response/investigation teams contingent, the&#xA;Deployed Operations Team, consisting of additional personnel and&#xA;equipment, would begin arriving at the TAL site for the orbiter&#xA;turnaround operation. NASA estimates it would take about 19 C-17/C-5&#xA;aircraft sorties, a significant Navy sealift operation, and 450 NASA&#xA;and contractor personnel to complete the turnaround. [...]&lt;/p&gt;&#xA;&lt;p&gt;Payloads and/or airborne support equipment will remain onboard the&#xA;orbiter for the flight back to Kennedy Space Center unless the&#xA;capability of the shuttle carrier aircraft, landing site location or&#xA;other requirements dictate other wise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Lightening the Orbiter at the TAL Site Before Ferrying to KSC&lt;/h3&gt;&#xA;&lt;p&gt;Weight limits of the &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/120269main_FS-013-DFRC.pdf&quot; rel=&quot;noreferrer&quot;&gt;SCA&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Basic weight, NASA 905, 318,053 lbs (144,269 kg), NASA 911, 323,034 lbs (146,528 kg)&lt;/li&gt;&#xA;&lt;li&gt;Maximum gross brake release weight, 710,000 lbs (322,056 kg)&lt;/li&gt;&#xA;&lt;li&gt;Maximum gross landing weight, 600,000 lbs (272,160 kg).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://commons.erau.edu/cgi/viewcontent.cgi?article=2443&amp;amp;context=space-congress-proceedings&quot; rel=&quot;noreferrer&quot;&gt;Space Transportation System Cargo Abort and Recovery Operations&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The ferry weight from contingency landing sites in Europe and Africa&#xA;is constrained to approx. 192,000 Ibs. (approx. 87,000 kg). The ferry&#xA;weight from the Pacific contingency landing sites is further&#xA;constrained to 154,000 Ibs. (approx. 70,000 kg).&lt;/p&gt;&#xA;&lt;p&gt;This requires not&#xA;only removal of the payload but removal of Orbiter main engines,&#xA;tires, landing gear and other components as well. In addition, the&#xA;Orbiter Z axis (vertical) and X axis (longitudinal) center of gravity&#xA;location must be within a limited envelope, as shown in Figure 1.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From The Conquest of Space, Ferrying the Shuttle - &lt;a href=&quot;http://www.theconquestofspace.com/2014/04/ferrying-shuttle-part-four-shuttle.html&quot; rel=&quot;noreferrer&quot;&gt;Part Four: The Shuttle Carrier Aircraft&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A typical route might take the pair from&#xA;continental Europe to England, then on to Iceland, then Canada, and&#xA;finally to the United States.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(Additional information might be found in JSC-NSTS-08934-VOLUME-4, Space Shuttle Orbiter Ferry Plan.)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Mating and Demating the Orbiter&lt;/h3&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/returntoflight/multimedia/Post-flight_gallery.html&quot; rel=&quot;noreferrer&quot;&gt;Photo gallery&lt;/a&gt; of Discovery mating at Edwards and demating at KSC (STS-114).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vHKbt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vHKbt.jpg&quot; alt=&quot;Nasa -- STS-114: Mission Complete&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.nasa.gov/returntoflight/multimedia/Post-flight_gallery.html&quot; rel=&quot;noreferrer&quot;&gt;Nasa -- STS-114: Mission Complete&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The mating structure above couldn't be used at a TAL site, so a crane would be available for the operation:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HRI6k.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HRI6k.jpg&quot; alt=&quot;Columbia being prepared at White Sands. Photo by Steve Schmidt.&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Columbia being prepared at White Sands. Photo by Steve Schmidt.&lt;br&gt;(Source: &lt;a href=&quot;http://www.airfields-freeman.com/NM/Airfields_NM_Alamagordo.htm&quot; rel=&quot;noreferrer&quot;&gt;Abandoned and Little-Known Airfields&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Ferrying the Orbiter&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/120269main_FS-013-DFRC.pdf&quot; rel=&quot;noreferrer&quot;&gt;Nasa Fact, Shuttle Carrier Aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;There were two SCA:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;NASA 905: Obtained from American Airlines in 1974.&lt;/li&gt;&#xA;&lt;li&gt;NASA 911: obtained from Japan Airlines in 1989.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;They were B747-100 and B747-100SR, modified by Boeing into their SCA configuration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yCmnB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yCmnB.jpg&quot; alt=&quot;Nasa Fact, Shuttle Carrier Aircraft&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/120269main_FS-013-DFRC.pdf&quot; rel=&quot;noreferrer&quot;&gt;Nasa Fact, Shuttle Carrier Aircraft&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;They were engined by four Pratt and Whitney JT9D-7J, and had a fuel capacity of 316,307 lbs (143,477 kg).&lt;/p&gt;&#xA;&lt;p&gt;The SCA didn't flight very fast: 250 kt or M .6, due to the drag from the orbiter and the additional vertical stabilizers. Its typical cruise altitude was also rather low to prevent freezing of the orbiter fluids:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;with orbiter, 13,000-15,000 ft&lt;/li&gt;&#xA;&lt;li&gt;unmated, 24,000-26,000 ft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The range was hence a bit shorter than if it flew higher. Typical range:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mated, typically 1000 NM (with reserves)&lt;/li&gt;&#xA;&lt;li&gt;Unmated, maximum 5500 NM.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-10-24T10:34:16.183" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23809" PostTypeId="2" ParentId="1189" CreationDate="2015-12-19T18:27:28.363" Score="2" Body="&lt;p&gt;Many of the reasons cited in the previous answers are valid. In consideration of these reasons, best practice should be to avoid flap control manipulation prior to exiting the runway. However, there are valid reasons to include flap retraction as a valid control manipulation upon touchdown. The primary reason I for which I would advocate the option is a need for a reduction in lift in strong and gusty winds crosswind conditions. For example, flap retraction at touchdown may be appropriate when landing a C172 in a 45° crosswind at 29G39. This technique should not be standard practice, nor should it be used by the inexperienced, nor should the inexperienced be in conditions which would call for the technique. But I would not say &quot;never&quot; appropriate.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2015-12-20T22:40:31.800" LastActivityDate="2015-12-20T22:40:31.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23810" PostTypeId="1" AcceptedAnswerId="23811" CreationDate="2015-12-19T18:51:14.593" Score="12" ViewCount="4530" Body="&lt;h2&gt;The Scenario:&lt;/h2&gt;&#xA;&lt;p&gt;An instrument-rated private pilot files and flies IFR while accompanied by a non-instrument-rated private pilot who is otherwise fully certified and endorsed to act as PIC in that aircraft under VFR flight rules. While in VMC, the instrument rated pilot uses a view limiting device in order to practice IFR scan and procedures towards maintaining currency, while the other pilot acts as safety pilot. Both pilots meet all medical and currency requirements for the flight.&lt;/p&gt;&#xA;&lt;h2&gt;The Question:&lt;/h2&gt;&#xA;&lt;p&gt;Can the safety pilot in the previous scenario &lt;em&gt;log as PIC&lt;/em&gt; that time during which he/she acted as safety pilot?&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; This question differs from the question, &lt;a href=&quot;https://aviation.stackexchange.com/questions/17069/how-should-time-as-safety-pilot-be-logged&quot;&gt;How should time as safety pilot be logged?&lt;/a&gt;. This question is not answered there; this question concerns whether or not a non-instrument-rated pilot is qualified as required crew during simulated instrument flight in VMC while operating on an IFR flight plan, and whether that pilot is qualified to act as PIC in the given scenario.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-08-26T21:43:48.090" Title="Can a non-instrument rated safety pilot log PIC during an IFR flight?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;logging&gt;&lt;pic&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23811" PostTypeId="2" ParentId="23810" CreationDate="2015-12-19T21:31:16.397" Score="9" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way that both pilots can log PIC is that the pilot using a view limiting device is logging PIC as sole manipulator and the safety pilot is logging PIC because he is acting PIC and a required crew member. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the flight is operating under an instrument clearance then the acting PIC must be instrument rated. If only the pilot with the view limiting device is rated then he is acting PIC and is the only one eligible to log PIC. The safety pilot is also not allowed to log SIC as a required crewmember without an instrument rating while operating under IFR.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are in actual IMC then you shouldn't be logging anything and they other guy shouldn't be wearing a view limiting device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want the PIC time ask your friend to fly VFR or get yourself an instrument rating. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-19T21:31:16.397" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="23812" PostTypeId="2" ParentId="23794" CreationDate="2015-12-19T21:37:00.950" Score="5" Body="&lt;p&gt;The answer depends on the aircraft. In most cases it is No, but for some it is Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29&quot; rel=&quot;noreferrer&quot;&gt;MiG-29&lt;/a&gt; has a green button at the right side of the stick which recovers the aircraft to a wings-level, shallow climb attitude if pressed. Note that the MiG-29, unlike its Western counterparts, is aerodynamically stable over the full angle of attack range beyond 90° and the flight control system can recover the aircraft from any attitude, altitude and thrust permitting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a quote from someone reporting his experience of flying a Malaysian MiG-29 (&lt;a href=&quot;http://sgforums.com/forums/1164/topics/64301&quot; rel=&quot;noreferrer&quot;&gt;link&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The stick has a red autopilot button on the left and a green auto&#xA;  recovery switch on the right for the disoriented pilot, and works by&#xA;  pressing the green panic button. The system recovers the jet to wings&#xA;  level and places the airplane in a slight climb if energy is&#xA;  available. This system is known to be reliable but is not often used.&#xA;  This is most likely due to the necessity of having to recognize that&#xA;  you are spatially disoriented prior to pushing the auto recovery&#xA;  button.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ziuXi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ziuXi.jpg&quot; alt=&quot;MiG-29 cockpit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MiG-29 cockpit (picture &lt;a href=&quot;https://farm4.staticflickr.com/3476/3765884851_ccfd583ca9_b.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The green button is clearly visible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-19T21:37:00.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23813" PostTypeId="2" ParentId="23810" CreationDate="2015-12-19T22:31:24.290" Score="-3" Body="&lt;p&gt;The issue for me is 91.109(c)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate a civil aircraft in &lt;strong&gt;simulated&lt;/strong&gt; instrument flight unless—&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The word simulated seems to me that while on an IFR flight plan the flight isn't simulated &lt;s&gt;hence there is no need for a safety pilot.&lt;/s&gt;  As a result, the other pilot irregardless of whether or not they are capable of acting as the legal pilot in command cannot log PIC time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are not a required crew member so they cannot log SIC time either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While in VMC conditions on an IFR flight plan it is prudent for all pilots to see and avoid other aircraft.  If one is wearing a view limiting device, &lt;s&gt;the other pilot is still not required due to being on an IFR flight plan.&lt;/s&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="12720" LastEditDate="2016-01-19T13:45:34.133" LastActivityDate="2016-01-19T13:45:34.133" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23814" PostTypeId="1" CreationDate="2015-12-19T23:54:43.283" Score="4" ViewCount="361" Body="&lt;p&gt;In the spirit of &lt;a href=&quot;https://aviation.stackexchange.com/questions/2570/in-case-of-emergency-is-it-possible-doable-to-land-a-small-propeller-driven-a&quot;&gt;our small airplane landing on a carrier question&lt;/a&gt;, I decided to up the ante slightly in a couple of ways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let us say some enterprising foreign navy has found a small flattop under their Christmas tree this year, and is in need of some aircraft to fly off it.  Of course, tactical aircraft are a necessity, and to that end, they could obtain some used A-4s as a starting point for their fledgling naval aviation branch.  However, there are other important aircraft on a carrier deck, one of them being the &lt;a href=&quot;https://en.wikipedia.org/wiki/Carrier_onboard_delivery&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carrier Onboard Delivery&lt;/a&gt; plane.  A bright young naval officer there decides &quot;Hey, we should see if some small civil planes might work for what we need&quot;, and does a bit of research, stumbling upon the &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter&quot; rel=&quot;nofollow noreferrer&quot;&gt;DHC-6-400&lt;/a&gt; with its widespread support base, ease of maintenance, good STOL performance, and current production availability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much modification would our enterprising foreign navy need to ask Viking Air to do to their order of DHC-6-400s to be fully usable from a carrier deck?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="22726" LastEditDate="2019-03-04T04:48:24.583" LastActivityDate="2019-03-04T04:48:24.583" Title="What modifications would be required to use a DHC-6-400 for Carrier Onboard Delivery work?" Tags="&lt;aircraft-carrier&gt;&lt;dhc-6&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23815" PostTypeId="2" ParentId="23814" CreationDate="2015-12-20T01:50:25.927" Score="5" Body="&lt;p&gt;DHC-6 has a reported &lt;a href=&quot;http://www.speedbird103.com/de-havilland-canada-dhc-6-twin-otter/&quot; rel=&quot;noreferrer&quot;&gt;takeoff roll of 210m and landing distance of 155m&lt;/a&gt; and as such can be operated from most of the &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_aircraft_carriers_in_service&quot; rel=&quot;noreferrer&quot;&gt;aircraft carriers in service&lt;/a&gt;, albeit with limited capability. If required, the aircraft can takeoff into the wind and for arrested recovery rear fuselage can be strengthened, though this looks unnecessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may need some changes for operating in marine environment like,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;better corrosion protection&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;strengthened landing gear&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Required naval equipment (for TO/landing).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course, all these modifications will eat into the payload. DHC-6 would be a rather small COD aircraft. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_C-2_Greyhound#Specifications_.28Reprocured_C-2A.29&quot; rel=&quot;noreferrer&quot;&gt;C-2 Greyhound&lt;/a&gt; used in USN has a payload greater than the MTOW of the twin otter.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-20T01:50:25.927" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23816" PostTypeId="2" ParentId="499" CreationDate="2015-12-20T03:17:44.680" Score="3" Body="&lt;p&gt;Turbochargers increase available engine performance by increasing the amount of fuel/air mixture that can be burned in the cylinders. This is accomplished by compressing the air before fuel is mixed in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The performance of a reciprocating aircraft engine is directly dependent on how much fuel can be burned and converted into heat energy, which in turn is converted into kinetic energy (motion). The amount of fuel that can be burned is dependent on how much air (actually the oxygen in the air) is available to burn with the fuel. An increase in altitude causes a decrease in air density and therefore less air available to be burned with the fuel. In a non-turbocharged (technically a &quot;normally aspirated&quot;) aircraft engine, the reduction in available air will cause a corresponding reduction in available power. A turbocharged engine overcomes this deficiency by compressing the air brought into the engine, thereby increasing the amount of fuel that can be burned with the air, and increasing the amount of power available.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="4474" LastEditDate="2015-12-23T23:35:12.003" LastActivityDate="2015-12-23T23:35:12.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23818" PostTypeId="1" CreationDate="2015-12-20T05:47:04.620" Score="5" ViewCount="678" Body="&lt;p&gt;I know Israel has highly modified F-16s, but just what are the structures on the sides and top, aft of the canopy? See this image of an Israeli F-16 compared to a normal one: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Gc2KK.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gc2KK.jpg&quot; alt=&quot;Israeli&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vs&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SYxlF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SYxlF.jpg&quot; alt=&quot;Normal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2015-12-20T08:59:22.717" Title="What are the structures on the sides of and aft of the canopy on Israeli F-16s?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2015-12-20T11:39:06.703" ContentLicense="CC BY-SA 3.0" />
  <row Id="23819" PostTypeId="1" AcceptedAnswerId="23910" CreationDate="2015-12-20T05:58:04.220" Score="6" ViewCount="2577" Body="&lt;p&gt;Take RNAV (GPS) Y RWY 36L and RNAV (GPS) Z RWY 36L at APC for examples,&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VL797.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VL797.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Cp2YG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cp2YG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All fixes and routes in the two approaches are similar. &#xA;The noticeable differences that I observe are minimums and WAAS CH number. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So some questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) How may I know which approach I am able to shoot? (or which WAAS channel is available?) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) Is the WAAS channel number automatically selected when I load the corresponding flight plan in G1000?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) ILS vs LPV: For an ILS approach, I may tune the localizer frequency and get both horizontal(CDI) and vertical (Glide Slope) information, without loading the flight plan. Can I get something similar with an LPV? I mean to get the LPV glide path guidance without loading any particular approach (set the WAAS CH number for instance?).&lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2015-12-24T18:54:43.507" Title="How may I verify WAAS channel number on G1000?" Tags="&lt;instrument-flight-rules&gt;&lt;autopilot&gt;&lt;instrument-procedures&gt;&lt;g1000&gt;&lt;flight-director&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23820" PostTypeId="2" ParentId="23818" CreationDate="2015-12-20T06:53:35.297" Score="1" Body="&lt;p&gt;Those are &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Conformal_fuel_tank&quot; rel=&quot;nofollow&quot;&gt;conformal fuel tanks&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12734" LastActivityDate="2015-12-20T06:53:35.297" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23821" PostTypeId="2" ParentId="23818" CreationDate="2015-12-20T08:59:22.717" Score="5" Body="&lt;p&gt;They're conformal fuel tanks, a type of external fuel tank designed for a specific aircraft type to reduce drag and other effects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, they increase fuel load and free up stations for weapons or even more fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular, the F-16 is a small platform with a modest fuel load and thus has a moderate radius &lt;em&gt;even when clean&lt;/em&gt;. But when it's &lt;em&gt;combat loaded&lt;/em&gt; with sensors and weapons, the additional weight and drag quickly eat into its combat radius, so one or two drop tanks are semi-permanently hung from its wings and/or belly. Don't quote me, but the CFT's almost double the F-16's internal fuel capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-16 wasn't originally conceived for ground attack, carrying bombs for many of its missions, but it quickly grew into the versatile multirole platform it is today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USAF can better accommodate the F-16's short range because it flies a huge fleet of ~450 aerial tankers to service 2000 fighters, whereas the IAF operates just 11 tankers for 400 fighters. (Obviously other USAF a/c also require tankers, not just fighters.) Also, the IAF doesn't have the luxury of other nearby friendly air bases it can fly out of. Thus, they use CFT's. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the benefit of hindsight, the original F-16 design team would probably have enlarged the internal fuel tanks from the start had they known how the F-16 would be used. &lt;/p&gt;&#xA;" OwnerUserId="7394" LastActivityDate="2015-12-20T08:59:22.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23822" PostTypeId="2" ParentId="23739" CreationDate="2015-12-20T16:13:40.377" Score="4" Body="&lt;p&gt;Indoor model helicopters would not be able to fly if the answer were no.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course it can, but the enclosure must be big &lt;strong&gt;or&lt;/strong&gt; small enough to avoid a &lt;a href=&quot;https://en.wikipedia.org/wiki/Toroid&quot; rel=&quot;nofollow noreferrer&quot;&gt;toroidal&lt;/a&gt; vortex from developing around the rotor. To summarize my answer, three conditions make it possible:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A very big enclosure which allows &lt;a href=&quot;https://aviation.stackexchange.com/questions/13397/why-would-a-helicopter-climb-in-a-spiral/13398?s=6%7C0.0655#13398&quot;&gt;enough forward speed&lt;/a&gt; so the helicopter never flies in its own wake,&lt;/li&gt;&#xA;&lt;li&gt;a very low ceiling or&lt;/li&gt;&#xA;&lt;li&gt;a very narrow enclosure.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Case 1 is trivial, so I dwell here on case 2: If you have flown an indoor model helicopter, you probably know that it is not advisable to come too close to the ceiling: The helicopter will become unstable and will be sucked right into it. This is caused by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/311/what-is-ground-effect&quot;&gt;ground effect&lt;/a&gt; (or better &lt;a href=&quot;http://www.rotaryforum.com/forum/showthread.php?t=24647&quot; rel=&quot;nofollow noreferrer&quot;&gt;ceiling effect&lt;/a&gt; in this case): The efficiency of the blades increases the closer they are to a horizontal surface and the helicopter needs less torque for the same lift. Once the rotor head is touching the ceiling, you need to cut power almost to zero to free it again. The same effect can now be used to fly in the constrained space because it will prevent the toroidal vortex of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/16108/how-do-modern-helicopters-tackle-vortex-ring-state?s=1%7C2.9102&quot;&gt;vortex ring state&lt;/a&gt; from developing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the explanation to case 3: If you insist on not touching any surface, the vortex will soon develop and reduce lift. How long you can hover depends on the air volume, and there is a minimum when the diameter of the enclosure is approximately twice the rotor diameter. Once the diameter becomes smaller, the vortex will again be inhibited, and when the enclosure is small enough the rotor will look like a fan in a duct. Now again less energy is needed for lift - just enough to maintain the necessary pressure difference through the rotor disc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I should add that this solution will best work with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Coaxial_rotors&quot; rel=&quot;nofollow noreferrer&quot;&gt;co-axial rotor&lt;/a&gt; and no tail sticking out at one end.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-12-21T21:01:48.757" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23823" PostTypeId="1" CreationDate="2015-12-20T17:10:04.337" Score="9" ViewCount="1834" Body="&lt;p&gt;Curious about the answer to this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/23819/how-may-i-verify-waas-channel-number-on-g1000&quot;&gt;How may I verify WAAS channel number on G1000?&lt;/a&gt;, I just found that &lt;a href=&quot;https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;SBAS/WAAS&lt;/a&gt; use in aviation seems to be poorly explained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular the &lt;a href=&quot;http://forums.jetcareers.com/threads/waas-approach-plate-channel-numbers.75299/&quot; rel=&quot;nofollow noreferrer&quot;&gt;WAAS &quot;channel number&quot;&lt;/a&gt; seems to suggest that some radio frequency is associated with a given WAAS approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qeduR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qeduR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image taken from the linked question)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the WAAS service is provided by only &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/waas/howitworks/&quot; rel=&quot;nofollow noreferrer&quot;&gt;two geosynchronous satellites&lt;/a&gt;, each one broadcasting on the same frequency the corrections for the whole US area. So there is no need to tune the WAAS receiver based on the airport location, the runway number, or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Localizer_performance_with_vertical_guidance&quot; rel=&quot;nofollow noreferrer&quot;&gt;LPV&lt;/a&gt; identifier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question: Are these 3 informations &lt;em&gt;strictly&lt;/em&gt; redundant (maybe not taking into account version numbers), and they exist only for triple-check purpose?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LPV approach name: RNAV (GPS) Y RWY 36L,&lt;/li&gt;&#xA;&lt;li&gt;WAAS channel number: WAAS CH 56613,&lt;/li&gt;&#xA;&lt;li&gt;WAAS approach ID (aka reference path identifier): W36A&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Could you confirm that selecting any of these values on the avionics will only change what is retrieved from the &lt;em&gt;local&lt;/em&gt; navigation database, and will not impact the GPS/WAAS data received?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I could understand if the approach were &lt;a href=&quot;https://en.wikipedia.org/wiki/Local_Area_Augmentation_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;LAAS/GBAS&lt;/a&gt; (local ground-based) instead of SBAS.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-12-20T21:25:08.067" Title="LPV/LP approach (RNAV with WAAS): What is actually the &quot;channel number&quot;?" Tags="&lt;navigation&gt;&lt;gnss&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23824" PostTypeId="1" AcceptedAnswerId="23826" CreationDate="2015-12-20T17:10:31.920" Score="6" ViewCount="3984" Body="&lt;p&gt;I am planning to build a large-scale LEGO airlier with most parts functional. Doing a little looking at pictures and research I see that commercial airliners have an underwing body that houses the flap track guides. How do they work mechanically?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-21T14:12:03.730" LastActivityDate="2018-10-13T10:17:04.463" Title="How do flap track guides work?" Tags="&lt;aircraft-design&gt;&lt;flaps&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23825" PostTypeId="2" ParentId="23823" CreationDate="2015-12-20T20:02:20.067" Score="2" Body="&lt;p&gt;&lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;source=web&amp;amp;rct=j&amp;amp;url=http://ww1.jeppesen.com/documents/aviation/notices-alerts/hubwatch/BriefingBullentins/bulletin_jep03D_WAAS.pdf&amp;amp;ved=0ahUKEwjXv8T6muvJAhXI0iYKHdmRBXkQFgglMAM&amp;amp;usg=AFQjCNERclFYGbAdLjMjjEb04dp-H3cFlw&amp;amp;sig2=9jbceewpV3buey5Ml3q-jw&quot; rel=&quot;nofollow&quot;&gt;This pdf&lt;/a&gt; by Jeppesen provides the meaning:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;WAAS Channel Number, unique to each airport, and  Reference Path&#xA;  Indicator (RPI), which is made up of the letter “W” plus two or  three&#xA;  characters representing the runway number.  These are shown in both&#xA;  the Briefing Strip (chart heading) and plan view.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the Channel Number provides the airport, and the RPI provides the runway number as well as the specific procedure. The combination of the two of them provides a specific approach at a specific airport, in much the same way that the title of the procedure on the approach plate is only meaningful if you combine it with the airport identifier. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as what you need to select in a particular avionics package, that depends on the design, but you are correct that it doesn't affect how it processes the GPS / WAAS signals. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2015-12-20T21:25:08.067" LastActivityDate="2015-12-20T21:25:08.067" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23826" PostTypeId="2" ParentId="23824" CreationDate="2015-12-20T21:27:43.820" Score="14" Body="&lt;p&gt;There are different ways of moving flaps. The trivial case where they rotate around a hinge point which lies within the airfoil contour does not increase wing area. Fowler-type, backward-moving flaps are possible in three general ways: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Douglas flap: Here the flap rotates around a single hinge line which lies substantially below the airfoil contour. As the name suggests, this is used on many Douglas Commercial aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gDTiN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gDTiN.jpg&quot; alt=&quot;Douglas flap&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Douglas flap, left: retracted (&lt;a href=&quot;http://www.airlinercafe.com/aviation_articles/dc9_guide/image159.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;); right: extended (&lt;a href=&quot;https://www.metabunk.org/data/attachments/5/5876-bc601fd95a5bfc332bf35c0fd675d23b.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Their long and narrow supports make them easy to recognize.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Four- or five-bar linkages: These are mechanically more complex, but enable a more compact mechanism. As their name suggests, four or five linkages are connected with bearings and enable a more complex movement. The drawing and the animated GIF below are taken from &lt;a href=&quot;https://en.wikipedia.org/wiki/Linkage_(mechanical)#Mobility&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt; and show the mobility m which increases with the number of joints. This would be my recommendation for a Lego model; just make sure that the forward bar is longer than the rear bar - this will give you a realistic movement of the flap.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/80cWs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/80cWs.png&quot; alt=&quot;Linkage mobility&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above: Linkage mobility (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/0/05/Linkage_mobility.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Below: Four bar linkage (picture &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:4_bar_linkage_animated.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IrXRH.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IrXRH.gif&quot; alt=&quot;four bar linkage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;Sliding block guide: Here you find real rails and rollers which move along them to enable the most complex and precise movement, even for multi-element flaps. While a four-bar linkage will have a continuously increasing ratio of deflection angle to backward shift, a sliding block guide makes it possible to set the deflection angle independent of the backward shift, and allows the biggest backward shift for a given size of the mechanism. See the Boeing 747 flap tracks below for an example.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dbvm4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dbvm4.jpg&quot; alt=&quot;Boeing 747 flap tracks&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747 flap tracks (picture &lt;a href=&quot;http://www.billzilla.org/747flaptrack.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note that the upper block is supporting the first flap segment and the lower block the second. Actuation is via a spindle; the linkage in the lower left corner is actually the mechanism for moving the flap fairing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-21T05:37:27.557" LastActivityDate="2015-12-21T05:37:27.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23827" PostTypeId="2" ParentId="23792" CreationDate="2015-12-20T22:56:59.073" Score="2" Body="&lt;p&gt;If the airway is too far away to accurately determine which leg you are going to intercept, why would you let the G1000 pick the leg you are going to intercept? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You know best what you want and, as you say, ATC may change your heading anyway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you shouldn't intercept automatically until you are fairly sure where you are intercepting. Instead you remain in HDG mode which gives you full control and makes it easy when ATC instructs you to change heading. Then when you are a couple of miles from intercepting you select the leg and let the G1000 do the magic if you want to. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Automation is there to relieve you from difficult or boring tasks. If you find that you spend a lot of time programming your FMS, it may be better to reduce the level of automation and spend the extra time on situational awareness. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recommend watching this America Airlines training video on &lt;a href=&quot;https://www.youtube.com/watch?v=pN41LvuSz10&quot; rel=&quot;nofollow&quot;&gt;automation dependency&lt;/a&gt; (a.k.a. &quot;Children of the magenta line&quot;). It addresses the FMS / autoflight dependecies for airline pilots. The video is over 15 years old and by now similar automation systems have entered the cockpits of small aircraft. Although some aspects of the video address a multicrew environment, the main points are equally valid for G1000 equipped single crew / single engine propeller aircraft.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2015-12-20T23:05:57.860" LastActivityDate="2015-12-20T23:05:57.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23828" PostTypeId="1" AcceptedAnswerId="23831" CreationDate="2015-12-21T00:28:14.240" Score="22" ViewCount="14872" Body="&lt;p&gt;I've been flying aircraft carrier approaches in a flight simulator lately and noticed that the carrier has an interesting layout. I have an image below where the landing runway is in red and the takeoff runway is in blue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fzOdQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fzOdQ.png&quot; alt=&quot;Aircraft carrier with takeoff and landing directions marked&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can understand the takeoff runway - taking off into the wind with the catapult so that you can get enough air flowing to take off. The part that confuses me is the position of the landing runway. It is at a slight angle to the direction of the carrier's motion, meaning that when I fly the approach I have to aim to the right of the carrier and let it move underneath me. It seems to me as though this would just complicate an already difficult procedure, particularly in rough weather conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why not just take off and land in the same direction? As far as I am aware the aircraft only take off forward of the jet blast shields i.e. at the tail of the blue arrow. This would leave plenty of room on the carrier for landing. The only time I can think this would be a problem would be when a pilot needs to abort the landing and quickly take off again when there is another jet waiting to take off ahead of him, though this would assume that aircraft were taking off at the same time as others were landing (I have no idea if this actually happens).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be great if someone could shed some light onto why aircraft carriers have this layout - I'm not a pilot, just been playing around in simulator.&lt;/p&gt;&#xA;" OwnerUserId="3878" LastEditorUserId="1467" LastEditDate="2017-12-07T13:34:46.680" LastActivityDate="2017-12-07T13:38:50.527" Title="What are the advantages of the angled flight deck layout used by some aircraft carriers?" Tags="&lt;aircraft-carrier&gt;" AnswerCount="6" CommentCount="7" ClosedDate="2017-12-07T21:52:42.620" ContentLicense="CC BY-SA 3.0" />
  <row Id="23829" PostTypeId="1" CreationDate="2015-12-21T00:34:22.690" Score="9" ViewCount="2103" Body="&lt;p&gt;When landing on aircraft carriers, a tailhook is used to snag one of the cables on the carrier deck, which slows the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the landing gear fails to deploy I have seen it is possible to make an emergency landing by landing on the belly - and I'm sure there are other options too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what would a pilot do if the tailhook failed to deploy when landing on a carrier? Is the carrier deck long enough for a pilot to stop without the tailhook? What else could a pilot do in this situation?&lt;/p&gt;&#xA;" OwnerUserId="3878" LastEditorUserId="15311" LastEditDate="2017-12-07T15:47:52.333" LastActivityDate="2019-08-25T18:41:17.190" Title="Is there a procedure for landing on an aircraft carrier when the tailhook fails to deploy?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;aircraft-carrier&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23830" PostTypeId="2" ParentId="23828" CreationDate="2015-12-21T00:40:37.027" Score="11" Body="&lt;p&gt;The angled part of the deck allows landing aircraft to go around if necessary as well as permitting simultaneous takeoffs and landings safely when that is necessary. As I understand it (perhaps a carrier pilot could enlarge on this), a carrier pilot wants a 4G landing impact. At the point of impact, he goes to full thrust so that if he doesn't catch a wire, he can safely fly off the end of the angled deck. If he does catch a wire, he immediately closes the thrust lever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They don't flare. Years ago I checked out a carrier pilot in a C182. He said the hardest part of flying the 182 was having to flare the aircraft for landing. He explained that for carrier landings, they fly the airplane onto the deck with no flare. The 4G desired impact figure came from him. I seem to remember also that he said they want to catch the third wire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I believe the preferred terminology is &quot;carrier traps&quot; rather than landings, but I'm not certain.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2015-12-21T19:15:09.997" LastActivityDate="2015-12-21T19:15:09.997" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23831" PostTypeId="2" ParentId="23828" CreationDate="2015-12-21T01:00:10.707" Score="26" Body="&lt;p&gt;This kind of layout is called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_deck#Angled_flight_deck&quot;&gt;angled flight deck&lt;/a&gt; (also called 'skewed' or 'canted' deck) and was first used by Royal Navy. There are a number of advantages to this layout compared to using the same direction of landing and takeoffs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It allows concurrent landings and takeoffs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By having an angled deck, the aircraft which fail to connect (with the arrestor cables) during landing can go around and try again without risk of damage to other (parked and taking off) aircraft).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main reason for the emergence of angled deck was the introduction of jet aircraft in naval operations, which due to their weight and high speeds required most of the deck available to complete an arrested landing. Also, in case of missed wires, it was possible to use a barrier in case of propeller aircraft, which was not possible in case of jet aircraft. According to Rear Admiral Dennis Campbell, &lt;a href=&quot;http://www.denniscambell.org.uk/4663/4690.html&quot;&gt;the inventor of angled deck&lt;/a&gt;,:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But with the advent of the heavier faster jets, it soon became obvious that the dimensions of the carrier's deck would impose a limit to the standard of aircraft that could be operated. The inevitable increase in weight and landing speed of the jets would make it impracticable to retain the existing combination of arrester wires/barriers/and deck park without a drastic reallocation of the deck space required to absorb the much longer pull-out of the wires. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Prior to the application of the angled deck, this caused significant problems and requirement of complex machinery to overcome.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ark sister ship and predecessor, the Eagle, was equipped with sixteen arrester wires and three different types of barrier (together with all their several hydraulic machines), and all this gear could only just cope with the first generation for (straight wing) jets.  No way would such a layout be good enough for the newer types.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The solution was to skew the flight deck by about 10 degrees (the HMS Ark Royal first had the flight deck angled by 5 degrees, which was then increased to 10) and use it for landing. This lead to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;The saving in arrester gear units and barriers – Ark needed only four wires and one (emergency only) barrier.  The reduction in weight and the extra space that this conferred enabled more mess-decks to be fitted in, thus reducing congestion in living spaces.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Since landing accidents would obviously be far less frequent, fewer aircraft and spare parts would be needed so costs would be greatly reduced. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Similarly, death and injuries to aircrew and deck handlers could be kept to a minimum – with a big boost to confidence and morale, not to mention the saving in training costs.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;As experience was gained of the new scheme, less obvious advantages came to light.  New areas of parking, (abaft the island for instance); an added flexibility in the relative wind speed and direction, easier and faster deck handling, less wear and tear on the command, etc.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Perhaps surprisingly, though the USN has adopted this system in its supercarriers, the RN dropped it later on.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-21T01:00:10.707" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23832" PostTypeId="2" ParentId="23829" CreationDate="2015-12-21T01:20:40.923" Score="16" Body="&lt;p&gt;The high landing speeds of modern jets mean that they cannot make anything but an arrested landing as the carrier flight deck is too small.The carriers usually have barricades to facilitate emergency landings. The following image shows a barricade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IZwgd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IZwgd.jpg&quot; alt=&quot;Barricade&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://usnhistory.navylive.dodlive.mil/2017/10/17/the-40th-anniversary-commissioning-of-uss-dwight-d-eisenhower-cvn-69/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the barricade, raised.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pyoor.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pyoor.jpg&quot; alt=&quot;Barriacade&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:US_Navy_051210-N-3488C-011_A_catapult_shooter_observes_the_raising_of_the_emergency-landing_barricade_during_flight_deck_drills_aboard_the_conventionally_powered_aircraft_carrier_USS_Kitty_Hawk_(CV_63).jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows an aircraft using a barricade.The aircraft was unable to make a normal arrested recovery because of damaged landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8TCEG.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8TCEG.gif&quot; alt=&quot;Barricade&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:US_Navy_DN-SC-93-04867_to_04876_S-3A_Viking_emergency_landing_USS_Abraham_Lincoln_(CVN-72)_animation.gif#/media/File:US_Navy_DN-SC-93-04867_to_04876_S-3A_Viking_emergency_landing_USS_Abraham_Lincoln_(CVN-72)_animation.gif&quot; rel=&quot;noreferrer&quot;&gt;US Navy DN-SC-93-04867 to 04876 S-3A Viking emergency landing USS Abraham Lincoln (CVN-72) animation&lt;/a&gt;&quot; by PH3 Eric Hayhurst - This Image was released by the United States Navy with the ID DN-SC-93-04867 to 04876 Commons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/watch-these-troubled-navy-jets-careen-into-aircraft-car-1748976393&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; for some other cases where barricades were used.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1467" LastEditDate="2017-12-07T13:33:10.300" LastActivityDate="2017-12-07T13:33:10.300" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23833" PostTypeId="1" AcceptedAnswerId="23965" CreationDate="2015-12-21T05:03:50.953" Score="3" ViewCount="3368" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pelikan_tail&quot; rel=&quot;nofollow&quot;&gt;Pelikan tail&lt;/a&gt; was originally proposed for the X-32.  Why was the Pelikan tail proposed rather than a V-tail?  What advantages and disadvantages does the Pelikan tail have compared to a V-tail or a conventional tail?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2015-12-31T10:51:34.873" Title="What are the advantages of a Pelikan tail compared to a V-tail?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23834" PostTypeId="1" AcceptedAnswerId="23835" CreationDate="2015-12-21T05:57:24.140" Score="2" ViewCount="324" Body="&lt;p&gt;I flew a long trip (&gt; 900nm) but the first leg, where I had a full stop landing to pick someone up, was only 24nm away from my starting point. For the FAA, a cross country trip counts as &gt; 50nm straight line distance from the starting point. How should I log this short leg of the greater XC trip? Just count it all as XC or just subtract the time of the short leg from the XC total in my log book?&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2015-12-21T06:57:46.897" LastActivityDate="2015-12-21T07:03:25.833" Title="Does the first portion of a trip that was &lt; 50nm count as XC on a long trip?" Tags="&lt;logging&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2015-12-21T15:36:36.823" ContentLicense="CC BY-SA 3.0" />
  <row Id="23835" PostTypeId="2" ParentId="23834" CreationDate="2015-12-21T06:57:37.157" Score="5" Body="&lt;p&gt;The relevant regulation is in 14 CFR 61.1(b)(3):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cross-country time means—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Except as provided in paragraphs (ii) through (vi) of this&#xA;  definition, time acquired during flight—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(A) Conducted by a person who holds a pilot certificate;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(B) Conducted in an aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(C) That includes a landing at a point other than the point of&#xA;  departure; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(D) That involves the use of dead reckoning, pilotage, electronic&#xA;  navigation aids, radio aids, or other navigation systems to navigate&#xA;  to the landing point.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) For the purpose of meeting the aeronautical experience&#xA;  requirements (except for a rotorcraft category rating), for a private&#xA;  pilot certificate (except for a powered parachute category rating), a&#xA;  commercial pilot certificate, or an instrument rating, or for the&#xA;  purpose of exercising recreational pilot privileges (except in a&#xA;  rotorcraft) under §61.101 (c), time acquired during a flight—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(A) Conducted in an appropriate aircraft;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(B) That includes a point of landing that was at least a straight-line&#xA;  distance of more than 50 nautical miles from the original point of&#xA;  departure; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(C) That involves the use of dead reckoning, pilotage, electronic&#xA;  navigation aids, radio aids, or other navigation systems to navigate&#xA;  to the landing point.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the rule under paragraph (ii)(B) is &quot;a flight&quot; that includes &quot;a&quot; point of landing more than 50nm from the point of departure.  It does not specify that all points of landing must be further than 50nm from the departure point, or even that the first point of landing must be further than 50nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the overall trip was over 50nm, does the FAA allow you to consider that 24nm leg to be part a single overall flight?  Unfortunately, the FAA doesn't provide a definition of &quot;flight&quot; in this context.  However, it is generally accepted that short stops (to pick up a passenger, refuel, eat lunch, etc.) can be logged as part of a single flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit to add:  Please also this this &lt;a href=&quot;https://aviation.stackexchange.com/questions/23459/faa-may-i-log-as-cross-country-a-flight-with-two-or-more-short-legs?rq=1&quot;&gt;previous question&lt;/a&gt;, and especially the &lt;a href=&quot;http://flighttraining.aopa.org/magazine/1998/October/199810_Flying_Smart_No_Dumb_Questions.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA article&lt;/a&gt; it links to.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-21T07:03:25.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23836" PostTypeId="2" ParentId="23833" CreationDate="2015-12-21T11:04:33.833" Score="7" Body="&lt;p&gt;The X-32 was Boeing's entry for the JSF contest, which was supposed to serve USAF, USMC and USN. JSF called for an affordable VTOL capable aircraft operated by all three services. Boeing decided to go for a tailless single piece delta with a direct lift system, similar to the Harrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c2hdY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c2hdY.jpg&quot; alt=&quot;X-32&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from militaryfactory.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The adoption of direct lift system and other considerations meant that X-32 had weight issues (They actually had to strip off some parts for VTOL). However, midway through the program, USN changed its requirements, requiring improved performance and payload capabilities. This caused serious problems for Boeing as its present design was expected to fall short of the requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to overcome this, Boeing decided to change the wing and tail design of X-32. &lt;a href=&quot;http://www.pbs.org/wgbh/nova/transcripts/3004_xplanes.html&quot; rel=&quot;noreferrer&quot;&gt;For tail design, two designs were proposed&lt;/a&gt;- a conventional four poster tail (like Lockheed's X-35) and a Pelikan tail (it was conceived by Ralph Pelikan, who worked for McDonnell Douglas and now for Boeing after their merger). The main points put forward in favor of Pelikan tail were,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It caused less drag compared to conventional tail&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Offer pitch control at high AoA.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It had better stealth characteristics (two tails would be better than four).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The design would look different from the Lockheed concept.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, the problem was that nobody has flown with this design so far. After some discussion, Boeing decided to go with the Pelikan tail. However, after a few days, the decision was reversed as the design was found to be &lt;a href=&quot;http://www.airspacemag.com/military-aviation/winner-take-all-3486459/?c=y%3Fno-ist&amp;amp;page=2&quot; rel=&quot;noreferrer&quot;&gt;heavier by a considerable amount&lt;/a&gt; as the larger control surfaces required beefier hydraulics and Boeing decided to go with a conventional tail, which turned out to be around 1500 lb lighter compared to the original design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the prototype was not actually modified due to lack of time. The modified aircraft would've looked like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xle6R.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xle6R.jpg&quot; alt=&quot;X-32 Schematic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from aerospaceweb.org&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Saab is testing a (sub-scale) &lt;a href=&quot;http://gripen4canada.blogspot.in/2014/08/speculating-on-saabboeing-t-x.html&quot; rel=&quot;noreferrer&quot;&gt;concept with Pelikan tail&lt;/a&gt; called the FS2020, which has Pelikan tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p7qXY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p7qXY.jpg&quot; alt=&quot;FS 2020&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from gripen4canada.blogspot.in&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2015-12-27T22:42:26.897" LastActivityDate="2015-12-27T22:42:26.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23837" PostTypeId="2" ParentId="701" CreationDate="2015-12-21T11:50:33.187" Score="5" Body="&lt;p&gt;Here are a couple of ground comfort related differences. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it's hot, and you're waiting in line for fuel, or if your plane isn't hangared, you can stand in the shade under a high wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to walk from fore of the wing to aft of the wing, to get the oil rag you forgot, with a high wing, you duck a bit and walk straight, with a low wing, you walk all the way around the wing. Twice. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-12-21T11:50:33.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23838" PostTypeId="2" ParentId="23805" CreationDate="2015-12-21T13:40:57.483" Score="15" Body="&lt;p&gt;This can depend on all kinds of things, so it's hard to give a definitive answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Many low-cost airlines park at remote stands as this is cheaper than parking at a jet-bridge.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some airports have jet bridges that can't handle particular aircraft types (often large aircraft at small airports) and therefore these aircraft must park at remote stands.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Related to the above, some airports have no customs facilities for jet bridge arrivals (or vice-versa) and therefore international flights must be parked at a remote stand and passengers bussed to customs/immigration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Sometimes a flight will be allocated a jet bridge in advance but then suffers from a delayed arrival. By the time it gets to the destination the jet bridge that was assigned to it is taken by another aircraft. In this case, the aircraft may have to be parked at a remote stand.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As you say, bad luck can play a role. Airports have a limited number of jet bridges and sometimes there's just no space for your aircraft. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Lastly, in my experience it is particularly common to get a remote stand if you arrive late in the evening: Some airlines like parking remotely in this circumstance as it's cheaper than parking overnight at a jet bridge.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As I said, it's hard to give a definitive answer but the above are some common causes for being placed at a remote stand.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2015-12-21T13:40:57.483" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23839" PostTypeId="1" AcceptedAnswerId="23865" CreationDate="2015-12-21T14:37:37.620" Score="12" ViewCount="984" Body="&lt;p&gt;The communication between the captain and first officer is of great importance, especially when it comes to agreeing who is the pilot flying. &lt;a href=&quot;https://aviation.stackexchange.com/questions/5078/how-is-aircraft-control-positively-transferred-between-pilot-flying-and-pilot-no&quot;&gt;This question&lt;/a&gt; asks for the procedures regarding taking/handing over control and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5091/how-are-conflicts-between-pilot-flying-and-pilot-not-flying-over-aircraft-contro&quot;&gt;this&lt;/a&gt; is also a related question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neither of these question discuss under what circumstances the pilot not flying should intervene &lt;em&gt;without&lt;/em&gt; verbally announcing their control of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Are there defined procedures for this?&lt;/li&gt;&#xA;&lt;li&gt;Is seniority sufficient to immediately intervene in some situations?&lt;/li&gt;&#xA;&lt;li&gt;Is it up to the crew to decide before-hand that the captain is allowed to &quot;help&quot; a less experienced first officer?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;https://www.youtube.com/watch?v=hnqJXs7hCIk&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; (at about 1:40), the first officer is landing the plane, and immediately after touch-down the captain intervenes by pushing the stick forward, apparently without being the pilot flying at the moment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://picma.info/sites/default/files/Documents/Background/Besco%20Co-pilots%20dilemma.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;This document&lt;/a&gt; is also related, although it focuses on when and how to intervene being the less experienced co-pilot. Key quote:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;You are damned if you ignore a Captain's mistakes! &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;You are damned if you do or say something about them!&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11665" LastEditorUserId="11665" LastEditDate="2018-01-25T13:07:32.717" LastActivityDate="2018-01-25T13:07:32.717" Title="Under what circumstances should the pilot not flying intervene without asking for aircraft control?" Tags="&lt;commercial-aviation&gt;&lt;pilots&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23840" PostTypeId="1" AcceptedAnswerId="24028" CreationDate="2015-12-21T17:12:17.760" Score="7" ViewCount="1948" Body="&lt;p&gt;What type of supersonic intake does the &lt;a href=&quot;http://www.dassault-aviation.com/en/defense/rafale/introduction/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassault Rafale&lt;/a&gt; use? Is it a Pitot Intake? It cannot be a Ramp Intake, nor can it be a Spike Intake / Cone Intake, and it does not seem as a Diverterless Supersonic Inlet either.&lt;br&gt;&#xA;Are there any explanations for the half-circular shape of the two intakes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sources for supersonic intake types: &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/inlet.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA Website&lt;/a&gt;, Aviation.SE Answers &lt;a href=&quot;https://aviation.stackexchange.com/a/13109/12485&quot;&gt;1&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/a/24017/12485&quot;&gt;2&lt;/a&gt;, &lt;a href=&quot;http://www.codeonemagazine.com/article.html?item_id=58&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin CODE ONE Magazine&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="15311" LastEditorDisplayName="user12485" LastEditDate="2017-12-05T16:31:01.240" LastActivityDate="2017-12-05T16:31:01.240" Title="What type of supersonic intake does the Dassault Rafale fighter jet have?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;inlet&gt;&lt;rafale&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23841" PostTypeId="1" AcceptedAnswerId="23844" CreationDate="2015-12-21T17:24:06.657" Score="15" ViewCount="4538" Body="&lt;p&gt;Lets assume this situation: In a controlled airport, two aircraft are approaching for landing. #1 is about to touch the runway (let's assume it is within 1~2 miles from touch zone).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then #2 declares a emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any rule that require that the first airplane starts a go around, either by its decision or by controller's?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some assumptions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There is enough separation from #1 to #2. If #1 was allowed to land and it successfully does, that will not significantly interfere with #2 landing.&lt;/li&gt;&#xA;&lt;li&gt;Airfield has just one runway.&lt;/li&gt;&#xA;&lt;li&gt;I'm limiting this to a international accepted, US and/or Brazilian rule.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My concern is that if some incident occurs with #1 on landing, like a gear collapsing, that may render the runway unsuable, causing trouble for the trailing aircraft in emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking in other words: Is an aircraft cleared to land even if another is approaching in a emergency situation?&lt;/p&gt;&#xA;" OwnerUserId="12715" LastEditorUserId="7532" LastEditDate="2017-01-05T02:06:22.973" LastActivityDate="2017-01-05T02:06:22.973" Title="What happens if an aircraft declares an emergency while there is another aircraft ahead cleared to land?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;emergency&gt;&lt;rules-of-the-air&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23842" PostTypeId="2" ParentId="23828" CreationDate="2015-12-21T17:29:51.837" Score="22" Body="&lt;p&gt;An angled flight deck resolves many problems identified during WWII with carrier combat and flight operations (in addition to some of the other issues related to jet aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first relates to the importance of not having a crash landing stop flight operations (or wreck staged/landed planes). For example, straight deck carriers often recovered planes in a fashion like this (images &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:USS_Saratoga_(CV-3)_landing_planes_on_6_June_1935_(80-G-651292).jpg&quot; rel=&quot;noreferrer&quot;&gt;from Wikipedia&lt;/a&gt;, the USS Saratoga):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eZqRA.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eZqRA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice the plane landing has a short distance to actually land/stop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is important to realize the implications of a crashed landing or an overlanding. A plane landing at this way, if it somehow jumped the barrier/missed/overshot is going to crash through many parked/staged planes. Clearing a flight deck, even with multiple elevators, is not instantaneous.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, let's consider the takeoff process. &lt;a href=&quot;https://en.wikipedia.org/wiki/File:USS_Saratoga_(CV-3)_off_New_York,_1934.jpg&quot; rel=&quot;noreferrer&quot;&gt;Again&lt;/a&gt;, look how many planes are staged on the flight deck:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sqQXx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sqQXx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sort of operation was typical in the era before and during World War Two. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's important to realize that most carrier configurations looked more like the ones here than what we think of when we think of a supercarrier when the angled flight decks were introduced. The experiences of those running WWII flight operations and the lessons learned drove the implementation of angled flight decks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine too if a plane returning to the ship suffers damages during landing or crashes. Given how the flight operations worked, this would prevent the ship from doing anything until the plane was dumped overboard/pushed out of the way. In a combat situation, precious minutes could mean the difference between a CAP being launched -- or no planes being launched. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, having two &quot;runways&quot; means multiple planes can be launched simultaneously. You get nearly twice as many launches per minute when having two runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USN was already experimenting with multiple launch points with a hangar deck catapult &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F6F_hangar_catapult_USS_Yorktown.jpg&quot; rel=&quot;noreferrer&quot;&gt;with the Essex class&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eR4qn.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eR4qn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not wildly successful, it shows the USN was already interested in having multiple launch points for planes (don't try landing through this area!). These were all removed eventually during WWII but the &lt;em&gt;need&lt;/em&gt; is indicated through their initial installation - six Essex carriers had hangar deck catapults installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, this indicates that there was a compelling problem to be solved with a straight flight deck and single launch/failure point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related to the increase in plane weights, having a longer &quot;landing&quot; zone allows heavier planes to actually accelerate upon landing in order to have enough airspeed to abort if needed. With either configuration as shown here, you would &lt;em&gt;never&lt;/em&gt; want to be accelerating on landing if not required to prevent stalling - if you did you are simply increasing the risk of crashing into the other parked planes. Especially as plane weights increased and speeds increased, the risk of overshooting the barriers increased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage is the increased ability for elevators to access the hangar deck. With a straight flight deck, you only can really have elevators that take away from your usable space. While the Essex class started this trend, having their elevators slightly sticking out from the ship, look at where the elevators were located in your image - they are completely out of the way of &lt;em&gt;both&lt;/em&gt; flight decks. This is another advantage of the angled flight deck, because it means you can operate the elevators and use them to stage planes without significantly affecting flight operations. A straight flight deck has minimal ability for this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last for this mini-book, having two &quot;flight decks&quot; means that in a combat situation, a single bomb doesn't put your ship out of action. Many US carriers were put out of action temporarily from single hits to their flight deck. Having two &quot;runways&quot; means that you build in some safety in that you can use your ship to launch or recover aircraft even if you take damage (again, keep in mind that during these conversions WWII was fresh in the minds of designers/naval officers).&lt;/p&gt;&#xA;" OwnerUserId="3675" LastEditorUserId="1467" LastEditDate="2017-12-07T13:38:50.527" LastActivityDate="2017-12-07T13:38:50.527" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23843" PostTypeId="1" AcceptedAnswerId="23850" CreationDate="2015-12-21T17:59:28.847" Score="22" ViewCount="2627" Body="&lt;p&gt;The Shuttle Orbiter crew were obviously in contact with ground control in Houston during their landing, but were they also in contact with any air traffic control, especially once they reached US airspace? Was US ATC involved in the landing in any way &lt;em&gt;other&lt;/em&gt; than keeping other traffic out of their way?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="4474" LastEditDate="2015-12-23T01:51:00.833" LastActivityDate="2021-04-20T18:27:16.470" Title="Was the Shuttle Orbiter in contact with air traffic control during its descent &amp; landing?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;space-shuttle&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23844" PostTypeId="2" ParentId="23841" CreationDate="2015-12-21T18:02:52.253" Score="24" Body="&lt;p&gt;No, the airport wouldn't be closed, and the #1 aircraft doesn't need to go around nor be sent around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The risk of him shutting down the runway is very slight, and is probably of the same magnitude of risk that sending him around to hold until #2 has landed &amp;amp; the runway has been checked and reopened, would put him into a low-fuel emergency state. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they are both about the same distance (actually, time) away, then the emergency aircraft has priority (assuming that he doesn't decide to hold in order to troubleshoot, burn down fuel, prepare for the landing, etc), but essentially closing the airport from the time that the emergency has been declared until the emergency aircraft lands, isn't something I've ever seen or heard of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The runway is often closed following an emergency landing until it can be checked by an airport vehicle, to ensure that it is clear of debris, spilled fuel/oil/hydraulic fluid/etc. And if the emergency aircraft can't clear the runway under its own power, it takes time to get it towed off, possibly pinning the landing gear (to prevent unintended retraction) first. Plus there may be an evacuation after the landing. So closing the runway for some time after the emergency aircraft lands, is entirely possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if the airport has planes in the pattern &amp;amp; the emergency aircraft is 50 miles out, it'd be better to let those who want/need to land, do so, rather than risk them running low on fuel airborne while awaiting the runway's reopening.  Same basic logic applies in the #1 / #2 scenario posed above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If aircraft regularly had their gear collapse &amp;amp; shut down runways unexpectedly, that would be a different story. But that's exceedingly rare, so that isn't the contingency that all planning is based on.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-21T18:20:22.647" LastActivityDate="2015-12-21T18:20:22.647" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23845" PostTypeId="2" ParentId="23841" CreationDate="2015-12-21T18:23:40.053" Score="2" Body="&lt;p&gt;It appears that the situation in your question is hypothetical. There are several aspects missing about the nature of the emergency, condition of the airport etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical situation will require that the airport will be ready to deal with the emergency, and clear the intended runway where the aircraft declaring emergency can land without delays. In clearing the runway, ATC can advise the #1 airplane to land and quickly clear the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again hypothetically speaking, after aircraft #2 has declared emergency, #1 can get into a situation where it would require more immediate assistance than #2.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2015-12-21T18:23:40.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23846" PostTypeId="2" ParentId="23843" CreationDate="2015-12-21T18:30:20.483" Score="8" Body="&lt;p&gt;Pretty sure the K.I.S.S. (Keep It Simple for the Spacemen) principle applies, and NASA owns the airspace.  Really, what is Center going to tell the shuttle? &quot;Go around?&quot; Nah. Welcome back? Probably, but that's more a distraction than anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC &lt;em&gt;would&lt;/em&gt; be involved in keeping the airspace clear of other traffic, certainly.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="595" LastEditDate="2015-12-21T18:39:04.457" LastActivityDate="2015-12-21T18:39:04.457" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23848" PostTypeId="2" ParentId="23840" CreationDate="2015-12-21T19:56:13.437" Score="7" Body="&lt;p&gt;The &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/p005676.pdf&quot; rel=&quot;noreferrer&quot;&gt;semi-ventral pitot air intakes&lt;/a&gt; is a compromise between Ventral and Side Mounting where the intakes and their ducts are placed on the lower corner of the fuselage. In order to prevent interaction in case of single engine failure Rafale uses two semi-circular air intakes on the windward side, separated by the body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://defenseissues.wordpress.com/tag/dassault-rafale/&quot; rel=&quot;noreferrer&quot;&gt;Intakes&lt;/a&gt; are separated from the fuselage so as to avoid capturing the fuselage boundary layer (layer of air where air slows from high velocity relative to aircraft at its edge to standstill at the surface itself) as boundary layer, if enters engine, impairs pressure recovery and increases distortion, thus lowering intake performance; space between intake and fuselage is called external boundary layer bleed. This space is repartitioned, and expansion waves from it energize canard root vortex. Engine cooling duct is also located in this layer. In case the Rafale is equipped with stronger engine, intakes can be enlarged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.globalsecurity.org/military/world/europe/rafale-design.htm&quot; rel=&quot;noreferrer&quot;&gt;architecture&lt;/a&gt; of the air intakes along with the nose and main undercarriages gives the capability for a large store to be carried under the fuselage, which is essential to achieve certain Air-to-Ground missions&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2015-12-22T15:44:19.513" LastActivityDate="2015-12-22T15:44:19.513" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23849" PostTypeId="2" ParentId="499" CreationDate="2015-12-21T22:17:11.863" Score="0" Body="&lt;p&gt;The turbocharger will rotate at a higher RPM at altitude, compressing the air such that the amount of fuel &amp;amp; air entering the combustion chamber is nearly the same as at sea level. From idle to full power will take longer at altitude and it may not be possible to successfully restart such an engine at high altitude until you have descended to an altitude where pressure is more favorable to start the engine.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastEditorUserId="4474" LastEditDate="2015-12-23T23:34:17.240" LastActivityDate="2015-12-23T23:34:17.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23850" PostTypeId="2" ParentId="23843" CreationDate="2015-12-21T23:49:35.003" Score="27" Body="&lt;p&gt;Well, sort of. The Kennedy Space Center, where the shuttle operations were conducted, &lt;a href=&quot;http://www.nasa.gov/mission_pages/shuttle/behindscenes/atcslffeature.html&quot;&gt;has an ATC&lt;/a&gt;. but then, the show was run by NASA, not FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shuttle operations were coordinated through the Aerospace Control Officer (ACO) at the Air Force 45 th Space Wing’s Eastern Range (it used a military TACAN). FAA was informed of the shuttle landing and nothing else. NASA simply cleared the airspace for a 30 mile radius around the intended landing site to prevent collisions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the trajectory of the shuttle landing, FAA issued a NOTAM called 'Space Shuttle Landing Operations Advisory' to warn the users that 25 miles to either side of the nominal reentry trajectory is potentially vulnerable to debris, but the airspace is not closed, like this example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FDC 9/1945 (A0856/09) - ...SPACE SHUTTLE LANDING OPERATIONS ADVISORY...&#xA;  EFFECTIVE 0911271848 UTC UNTIL 0911271923 UTC SPACE SHUTTLE&#xA;  LANDING OPERATIONS 25 NM EITHER SIDE OF THE LINE BETWEEN&#xA;  2743S/17214W 0411N/16214W 2925N/13455W 3440N/11828W 3457N/11745W&#xA;  FROM SURFACE TO UNLIMITED. WIE UNTIL UFN. CREATED: 25 NOV 21:11 2009&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For these actions, Special Use Airspace was activated. The ACO coordinates these actions with the FAA’s ARTCC (Air Route Traffic Control Center) in Miami, Florida&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-21T23:49:35.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23851" PostTypeId="2" ParentId="23841" CreationDate="2015-12-22T00:10:58.420" Score="5" Body="&lt;p&gt;Your question is a little vague; depends on the nature of the emergency for aircraft #2. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Declaring an emergency provides the PIC with the power to obtain priority over any other aircraft. If the PIC of aircraft #2 determined that they needed aircraft #1 to execute a go-around, then pilot of #1 aircraft would be expected to do that if able.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will also add that this scenario is highly unlikely because required separation between the two aircraft would have already established enough time for #1 to land and clear the runway before #2 could get there - regardless of the situation. &lt;/p&gt;&#xA;" OwnerUserId="12745" LastEditorUserId="572" LastEditDate="2015-12-22T09:19:28.820" LastActivityDate="2015-12-22T09:19:28.820" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23853" PostTypeId="2" ParentId="23843" CreationDate="2015-12-22T17:19:23.370" Score="3" Body="&lt;p&gt;It should also be noted that during at least part of the decent the &lt;a href=&quot;https://en.wikipedia.org/wiki/Communications_blackout#Spacecraft_reentry&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shuttle was incapable of radio transmissions&lt;/a&gt;. This was a problem common to all space craft reentering the atmosphere. The problem was &lt;a href=&quot;https://en.wikipedia.org/wiki/Tracking_and_Data_Relay_Satellite_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;apparently solved latter in the space program with the TDRS communication platform&lt;/a&gt; but the early shuttles were subject to a black out that lasted as long as 30 minutes. Since the US does not have an official definition of the start of space (although they use the generally accepted &lt;a href=&quot;https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line&quot; rel=&quot;nofollow noreferrer&quot;&gt;Karman line&lt;/a&gt;) its hard to even say where airspace ends and space begins. There is technically no upper bound to Class E airspace here in the US, the official wording is&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a289b62161e4bf976b6f4499b24c1965&amp;amp;mc=true&amp;amp;node=sp14.2.71.e&amp;amp;rgn=div6&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;§71.71   Class E airspace. Class E Airspace consists of:&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) The airspace of the United States, including that airspace&#xA;overlying the waters within 12 nautical miles of the coast of the 48&#xA;contiguous states and Alaska, extending upward from 14,500 feet MSL up&#xA;to, but not including 18,000 feet MSL, &lt;strong&gt;and the airspace above FL600&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Note: you dont need to contact ATC to enter class E but they will need to pass through the class A at some point.&lt;/p&gt;&#xA;&lt;p&gt;Also of some interest, you need a valid &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a289b62161e4bf976b6f4499b24c1965&amp;amp;mc=true&amp;amp;node=se14.4.460_15&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA pilots license with an instrument rating&lt;/a&gt; to fly a reentry vehicle.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(c) A pilot and a remote operator must—&lt;/p&gt;&#xA;&lt;p&gt;(1) Possess and carry an FAA pilot certificate with an instrument rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;All re-enty and launch paths must be filed with the FAA as well (I assume this is to they can issue the TFR)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a289b62161e4bf976b6f4499b24c1965&amp;amp;mc=true&amp;amp;node=se14.4.431_179&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;§431.79   Reusable launch vehicle mission reporting requirements.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) Not less than 60 days before each RLV mission conducted under a&#xA;license, a licensee shall provide the FAA with the following&#xA;information:&lt;/p&gt;&#xA;&lt;p&gt;(1) Payload information in accordance with 14 CFR §415.59 of this&#xA;chapter and §431.57; and&lt;/p&gt;&#xA;&lt;p&gt;(2) Flight information, including the vehicle, launch site, planned&#xA;launch and reentry flight path, and intended landing sites including&#xA;contingency abort sites.&lt;/p&gt;&#xA;&lt;p&gt;(3) Launch or reentry waivers, approved or pending, from a federal&#xA;Federal range for at which the launch or reentry will take place, that&#xA;are unique and may affect public safety.&lt;/p&gt;&#xA;&lt;p&gt;(b) Not later than 15 days before each licensed RLV mission, a&#xA;licensee must notify the FAA, in writing, of the time and date of the&#xA;intended launch and reentry or other landing on Earth of the RLV and&#xA;may utilize the FAA/U.S. Space Command Launch Notification Form,&#xA;contained in part 415, Appendix A, of this subchapter for doing so.&lt;/p&gt;&#xA;&lt;p&gt;(c) A licensee must report a launch accident, launch incident, reentry&#xA;accident, reentry incident, or other mishap immediately to the FAA&#xA;Washington Operations Center and provide a written preliminary report&#xA;in the event of a launch accident, launch incident, reentry accident,&#xA;or reentry incident, in accordance with the mishap investigation and&#xA;emergency response plan submitted as part of its license application&#xA;under §431.45.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Directly to the point the FAA does require a communications plan but seems to specify more what needs to be communicated than mandating they are involved.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a289b62161e4bf976b6f4499b24c1965&amp;amp;mc=true&amp;amp;node=se14.4.431_141&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;§431.41   Communications plan.&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) An applicant shall submit a plan&#xA;providing vehicle safety operations personnel communications&#xA;procedures during the mission. Procedures for effective issuance and&#xA;communication of safety-critical information during the mission shall&#xA;include hold/resume, go/no go, contingency abort, if any, and&#xA;emergency abort commands by vehicle safety operations personnel. The&#xA;communications plan shall describe the authority of vehicle safety&#xA;operations personnel, by individual or position title, to issue these&#xA;commands. The communications plan shall ensure that—&lt;/p&gt;&#xA;&lt;p&gt;(1) Communication networks are assigned so that personnel identified&#xA;under this section have direct access to real-time, safety-critical&#xA;information required for making decisions and issuing commands;&lt;/p&gt;&#xA;&lt;p&gt;(2) Personnel identified under this section monitor a common intercom&#xA;channel for safety-critical communications during launch and reentry;&lt;/p&gt;&#xA;&lt;p&gt;(3) A protocol is established for utilizing defined radio&#xA;communications terminology; and&lt;/p&gt;&#xA;&lt;p&gt;(4) Communications affecting the safety of the mission are recorded in&#xA;a manner that accurately reflects communications made on individual&#xA;channels, synchronized time coding, and sequence of communications.&lt;/p&gt;&#xA;&lt;p&gt;(b) An applicant shall submit procedures to ensure that licensee and&#xA;reentry site personnel, if any, receive a copy of the communications&#xA;plan required by this section and that the reentry site operator, if&#xA;any, concurs with the communications plan.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;You can find &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a289b62161e4bf976b6f4499b24c1965&amp;amp;mc=true&amp;amp;tpl=/ecfrbrowse/Title14/14cfr431_main_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;all the FAA regs on space flight here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-22T17:29:00.133" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23854" PostTypeId="1" AcceptedAnswerId="23859" CreationDate="2015-12-22T18:22:45.407" Score="13" ViewCount="1170" Body="&lt;p&gt;Yesterday (Dec 21, 2015), I was on board &lt;a href=&quot;http://www.flightradar24.com/data/airplanes/ei-efw/#853e5a7&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ryanair flight FR4966&lt;/a&gt; from London Stansted (STN) to Lamezia Terme (SUF). The aircraft was a Boeing 737-800, registration EI-EFW.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On takeoff, the climbing pattern didn’t seem very regular to me. It was clear that the engines were first running at full power, but then decreased their thrust and our altitude seemed not to increase as it would regularly do. I was certain we were about to return to STN due to some kind of malfunctioning. However, we reached our destination flawlessly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, I checked the climbing pattern, and my impression was confirmed. You can see below that the climbing pattern was initially steep, but at an altitude of approximately 5,700&amp;nbsp;feet, the aircraft stopped climbing and proceeded at the same altitude for about 5 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question:&lt;/strong&gt; what caused this steady situation? Did the aircraft undergo a malfunctioning that the cabin crew was able to cope with? Or was it just due to the fact that we were overflying London — a congested airspace — and that was our assigned altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hWu2y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hWu2y.jpg&quot; alt=&quot;Ryanair flight FR4966 ground track and altitude profile&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="1696" LastEditDate="2016-06-14T16:51:51.490" LastActivityDate="2016-06-14T16:51:51.490" Title="What could cause an irregular climbing pattern on takeoff?" Tags="&lt;altitude&gt;&lt;climb&gt;&lt;groundspeed&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23855" PostTypeId="5" CreationDate="2015-12-22T19:08:50.243" Score="0" Body="&lt;p&gt;Angle of Attack (AoA) is the angle between the oncoming air or &quot;relative wind&quot; and some reference line on a structure.  For an airfoil, the most common reference line is a line from the foremost point on the leading edge to the aftmost point on the trailing edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For highly cambered airfoils (or airfoil + flaps) this line may exist partially outside the structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Angle of Attack is very useful in predicting aerodynamic stalls, coefficient of lift, etc.&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="52" LastEditDate="2015-12-22T19:41:36.767" LastActivityDate="2015-12-22T19:41:36.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23856" PostTypeId="4" CreationDate="2015-12-22T19:08:50.243" Score="0" Body="Usually refers to the angle between the oncoming air and the wing." OwnerUserId="52" LastEditorUserId="1696" LastEditDate="2015-12-22T19:20:46.027" LastActivityDate="2015-12-22T19:20:46.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23857" PostTypeId="2" ParentId="23854" CreationDate="2015-12-22T19:23:00.003" Score="12" Body="&lt;p&gt;Looks like an intermediate altitude assignment from atc. A look at the standard instrument departure plates (SID's) for Stansted shows that the final altitude on some of the procedures is 6000 ft. They probably had to stay at that altitude until the departure controller passed them off to the en route controller who assigned them their cruise altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the initial IFR clearance, if I'm not mistaken, clearance delivery will give them a time to expect this assignment. The clearance will say something like &quot;climb via [name of SID], expect flight level 350 one zero minutes after takeoff.&quot; My wording may be off. The departure controller will assign whatever altitude they need them to be at. Usually what's on the procedure. So they stay at that altitude until the en route controller assigns their cruise alt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/nkADP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I picked a random SID plate for Stansted. At the bottom of the plate it tells what altitude they have to be at by a certain point. Looks like they have to get to 5000 ft pretty quickly.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2015-12-22T19:34:12.800" LastActivityDate="2015-12-22T19:34:12.800" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23858" PostTypeId="2" ParentId="22904" CreationDate="2015-12-22T19:23:56.090" Score="1" Body="&lt;p&gt;In some regards there is but this depends on what you consider &lt;em&gt;extreme weather&lt;/em&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On one hand there are physical limits to which a plane can be landed when it comes to wind both head on and cross winds. Granted they are cases they may never or only rarely come up you may simply not be able to land the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you have made it to the airport and are able to land...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some check lists and different procedures that me be executed for different weather. Snow and wet runways in general may see a longer landing distance and roll out however this is not &quot;special&quot; training as landing distance should always be calculated based on conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approaches are flown as published but changing winds and weather may cause the pilot to react differently or do different things to fly the approach. For example if you compare a calm wind approach to a dry runway with a wind sheared approach to a wet runway you may see some differences. The pilot may elect to come in a few knots over Vref and possibly with less flaps in a wind shear situation. Again this is not special training as much as it is standard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a contaminated runway the pilot may chose to preform something like a short field landing so as not to potentially collapse the nose gear. All pilots (even GA) are trained in this maneuver. There are so many possible situations here it would be hard to train for ever one but some are trained for or a checklist exits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Side Story&lt;/em&gt;: I was talking to a commercial pilot recently who flies the 777 and he was telling me a story of a time during training in the sim where they gave them heavy rain and 40Kts of wind shear (no one could successfully land the plane that day in his group in the sim). So they do at least throw situations like that at pilots in the sim, if they do it all the time I cant say. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-12-22T19:23:56.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23859" PostTypeId="2" ParentId="23854" CreationDate="2015-12-22T19:26:04.447" Score="21" Body="&lt;p&gt;The brief period of leveling off is not unique to the flight on that day. Looking at track logs for &lt;a href=&quot;http://flightaware.com/live/flight/RYR4966/history/20151220/0645Z/EGSS/LICA&quot; rel=&quot;noreferrer&quot;&gt;previous days&lt;/a&gt;, it always levels off at around 7,000 feet for some period.&lt;/p&gt;&#xA;&lt;p&gt;As Terry &lt;a href=&quot;https://aviation.stackexchange.com/questions/23854/what-could-cause-an-irregular-climbing-pattern-on-takeoff#comment55460_23854&quot;&gt;commented&lt;/a&gt;, this is most likely to deal with the congested airspace. Other routes coming into and out of the London area probably pass through the same space, and keeping flights departing Stansted at a lower altitude prevents them from interfering with other traffic.&lt;/p&gt;&#xA;&lt;p&gt;Looking at a &lt;a href=&quot;http://www.ead.eurocontrol.int/eadbasic/pamslight-7B0A1E3D2F82DA364E20D3A11F84D94B/7FE5QZZF3FXUS/EN/Charts/AD/AIRAC/EG_AD_2_EGSS_6-4_en_2014-05-29.pdf&quot; rel=&quot;noreferrer&quot;&gt;standard departure chart&lt;/a&gt;, there is a warning box:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;WARNING&lt;/p&gt;&#xA;&lt;p&gt;Due to interaction with other routes, do not climb above 5000 until instructed by ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This looks to be the route followed by this flight, at least to the DETLING VOR, so it would be expected that ATC will need to limit the flight's climb until clear of other traffic.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-22T19:26:04.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23860" PostTypeId="1" CreationDate="2015-12-22T21:53:21.530" Score="4" ViewCount="448" Body="&lt;p&gt;I have a job that requires me to travel on a small company plane with a company &quot;commercial&quot;pilot. I only have my PPL. If I am certified in the type of aircraft may the pilot allow me to fly &quot;solely manipulate the controls&quot; of the aircraft, while he clearly remains the PIC and responsible for the flight? If I am rated in the aircraft could I log those hours?&lt;/p&gt;&#xA;" OwnerUserId="12753" LastActivityDate="2016-03-04T23:37:23.297" Title="Can a someone with just a PPL log PIC time on a non-transport commercial flight?" Tags="&lt;commercial-aviation&gt;&lt;commercial-operations&gt;&lt;ppl&gt;&lt;logging&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23861" PostTypeId="2" ParentId="23860" CreationDate="2015-12-22T22:18:18.220" Score="4" Body="&lt;p&gt;Yes, you can log PIC in an aircraft category and class that you are certified to fly. You can log that time during which you are the sole manipulator of the controls. This is the case even if another crew member (the commercial pilot) is the acting PIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=afcba5c1c15d90c673f06237d89059a0&amp;amp;mc=true&amp;amp;node=se14.2.61_151&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51 (e)&lt;/a&gt; for this and other situations allowing logging of PIC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following is the relevant section of 61.51 (e):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) &lt;em&gt;Logging pilot-in-command flight time.&lt;/em&gt; (1) A sport, recreational,&#xA;  private, commercial, or airline transport pilot may log pilot in&#xA;  command flight time for flights-&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an&#xA;  aircraft for which the pilot is rated, or has sport pilot privileges&#xA;  for that category and class of aircraft, if the aircraft class rating&#xA;  is appropriate;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-04T23:37:23.297" LastActivityDate="2016-03-04T23:37:23.297" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23862" PostTypeId="1" AcceptedAnswerId="23866" CreationDate="2015-12-22T23:25:43.760" Score="13" ViewCount="2208" Body="&lt;p&gt;Would it have been possible to equip the Concorde with swing-wings to help with lift at lower speeds? The delta wings on the aircraft worked well at high speeds, but it took a long time for it to achieve takeoff speed. A swing-wing would give it the aspect ratio for low speeds and delta form for the high speeds.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="1696" LastEditDate="2015-12-23T15:44:59.543" LastActivityDate="2015-12-23T15:44:59.543" Title="Could Concorde have used swing wings?" Tags="&lt;aircraft-design&gt;&lt;supersonic&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23863" PostTypeId="2" ParentId="23862" CreationDate="2015-12-22T23:25:43.760" Score="10" Body="&lt;p&gt;Well, it would help with low speed lift, but it would have the following problems:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The fuel tanks in the wings would have to be rearranged significantly affecting the CG, CL, and CP. As seen in the diagram below, the fuel tanks fill most of the wing, so the wing at low-speed mode would create stresses on the airframe as well.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DR8Xg.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DR8Xg.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;The engines would also have to be relocated to another position, which without even more modifications to this airframe could not have been done.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The swinging mechanism for the wing would have taken up much room because it had to move a wing of such size.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So, if the Concorde would have had swing-wings, it would have been a radically different airframe. However, because of the difficulty of making a swing-wing mechanism for such a large aircraft (Existing swing-wing aircraft are either small compared to airliners or have plenty of room for the mechanism) and the many more forces involved with this, it would not have been a good idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Diagram and source &lt;a href=&quot;http://concordesst.com/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-23T13:17:26.727" LastActivityDate="2015-12-23T13:17:26.727" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23864" PostTypeId="2" ParentId="23860" CreationDate="2015-12-22T23:36:34.280" Score="3" Body="&lt;p&gt;Please note that &lt;em&gt;being&lt;/em&gt; PIC and &lt;em&gt;logging&lt;/em&gt; PIC are different things.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/1.1&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 1.1&lt;/a&gt; defines the Pilot in Command as the person who,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(1) Has final authority and responsibility for the operation and safety of the flight;&lt;/p&gt;&#xA;&lt;p&gt;(2) Has been designated as pilot in command before or during the flight; and&lt;/p&gt;&#xA;&lt;p&gt;(3) Holds the appropriate category, class, and type rating, if appropriate, for the conduct of the flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Basically, at any given time, there can only be one acting PIC on a flight, no matter how many pilots are on board the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.51 (e)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(e) Logging pilot-in-command flight time. (1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights-&lt;/p&gt;&#xA;&lt;p&gt;(i) When the pilot is the sole manipulator of the controls of an aircraft for which the pilot is rated, or has sport pilot privileges for that category and class of aircraft, if the aircraft class rating is appropriate;&lt;/p&gt;&#xA;&lt;p&gt;(ii) When the pilot is the sole occupant in the aircraft;&lt;/p&gt;&#xA;&lt;p&gt;(iii) When the pilot, except for a holder of a sport or recreational pilot certificate, acts as pilot in command of an aircraft for which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted; or&lt;/p&gt;&#xA;&lt;p&gt;(iv) When the pilot performs the duties of pilot in command while under the supervision of a qualified pilot in command provided,&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The end result is that more than one pilot &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Learn-to-Fly/Aviation-Subject-Report-Logging-Pilot-in-Command-PIC-Time&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;can&lt;/em&gt; log PIC time&lt;/a&gt; when there can only be one PIC on a given flight.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-23T08:56:04.633" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23865" PostTypeId="2" ParentId="23839" CreationDate="2015-12-22T23:41:03.280" Score="10" Body="&lt;p&gt;There is &lt;strong&gt;transfer of control&lt;/strong&gt; -- &quot;I have the aircraft&quot; / &quot;You have the aircraft.&quot;  Then there is &lt;strong&gt;intervening&lt;/strong&gt; -- which may or may not involve a transfer of control... directing &quot;you're getting slow, ADD POWER NOW&quot; may be a more effective example of intervening than taking control, depending on the phase of flight &amp;amp; other circumstances.  (It's easier for a First Officer to intervene with a directive &quot;add power&quot; or &quot;go around&quot; than than for him to take the aircraft!)  &lt;strong&gt;And then there is what was shown in the video&lt;/strong&gt;, which looks like neither of the above -- simply crew duties as @Lnafziger commented. The captain there didn't take over control (yet -- the video ends before he takes over to taxi), they simply both pushed forward on the control column -- put weight on the nosewheel for better steering, perhaps.  Looked perfectly normal &amp;amp; expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question as asked (&quot;Under what circumstances should the pilot not flying intervene without asking for aircraft control?&quot;), there are plenty of times when intervening without taking control could be appropriate -- the directive callout (&quot;ADD POWER!&quot;), or correcting an aircraft system or Flight Management Computer setting, for example.  There are also a smaller set of times when &quot;I have the aircraft!&quot; is appropriate: a disoriented pilot is about to fly into an unusual attitude, or a pilot is incapacitated in a phase of flight where there is no time for &quot;hey, are you okay?&quot; to differentiate between distracted &amp;amp; incapacitated.  The captain always &lt;strong&gt;&lt;em&gt;has&lt;/em&gt;&lt;/strong&gt; the prerogative to take over, although there are plenty of times when something else is a better choice -- directing &quot;go around&quot; instead of taking the aircraft at low altitude to try &amp;amp; salvage a bad landing, for instance.  Particularly in cases of incapacitation, the FO also has that option, but realistically, he may have more explaining to do than the captain would have if roles were reversed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a pure training situation (initial formation flying in the military comes to mind), there are times when control may transfer back &amp;amp; forth... the student flies as far as he can, starts to get out of position, the instructor takes the aircraft, puts it back into position, the student is given control again, etc.  But that's not really the sort of scenario you'd see in airline operations.  There might be times the pilot-monitoring captain (i.e. he is the pilot not-flying on the FO's leg) might take over the FMC programming rather than talking the FO through the necessary changes -- sometimes it's just better to do it &amp;amp; explain what you're doing rather than talk through each entry and button press.  But that's again not really the same as &quot;I have the aircraft.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With qualified crews in the airline world, it just isn't all that common that a situation arises where one pilot has to assume control outside of the normal transfers (i.e. the normal transfer to the captain on landing if he has the only nosewheel steering tiller).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, as noted in the comments, &lt;strong&gt;&lt;em&gt;every&lt;/em&gt;&lt;/strong&gt; transfer, both expected and unexpected, needs to be verbalized by both pilots: &quot;I have the aircraft.&quot;  &quot;You have the aircraft.&quot;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-23T01:42:22.043" LastActivityDate="2015-12-23T01:42:22.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23866" PostTypeId="2" ParentId="23862" CreationDate="2015-12-23T00:06:47.037" Score="26" Body="&lt;p&gt;Actually, the Boeing design for the SST (Super Sonic Transport), the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_2707&quot; rel=&quot;noreferrer&quot;&gt;Boeing 2707&lt;/a&gt; had a swing wing (swing wing was the hot thing during that time). It is instructive to look at what happened to that design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uZiaQ.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uZiaQ.gif&quot; alt=&quot;2707 SST&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from up-ship.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 2707 concept was a larger aircraft, with a 174' wingspan for TO/landing and low speed regime (In comparison, Concorde had a 84' wingspan and carried half the passengers). While the wings were swept back, the wing area increased from 1828 $m^{2}$ to 2743 $m^{2}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines were carried on the stabilizers. During the development Boeing had significant problems associated with the swing wing mechanism. Concerns about stability and payload capability lead the design to be lengthened and added canard to the front to meet rotation requirements, though the new design 2707-200 kept the swing wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8LU0l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8LU0l.jpg&quot; alt=&quot;2707-200&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from up-ship.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, these changes did little to solve the problems. When kept near the centerline, the hinge mechanism interfered with the undercarriage. The hinge mechanism was so heavy that it negated the advantages of swing wing, leading to a very poor payload to weight ratio. Studies indicated that the aircraft would run out of fuel halfway across the Atlantic, essentially killing the project.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, Boeing decided to use a fixed wing platform in its next iteration, the 2707-300, which looked quite similar to Concorde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/11vkJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/11vkJ.png&quot; alt=&quot;2707-300&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Boeing_2707-300_3-view.svg#/media/File:Boeing_2707-300_3-view.svg&quot; rel=&quot;noreferrer&quot;&gt;Boeing 2707-300 3-view&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Nubifer&quot; rel=&quot;noreferrer&quot; title=&quot;User:Nubifer&quot;&gt;Nubifer&lt;/a&gt; - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2015-12-23T15:43:20.537" LastActivityDate="2015-12-23T15:43:20.537" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23867" PostTypeId="1" AcceptedAnswerId="23876" CreationDate="2015-12-23T00:56:26.910" Score="11" ViewCount="12323" Body="&lt;p&gt;The ILS / LOC approach at KCXY states radar is required. I understand I can't fly the approach if not in radar contact. However, if flying the LOC approach I think I can identify both final and HORVI (for lower minimums) using HAR VOR. There's no reason I'd need the controller to call out a fix. If that is true, why is radar required? I think it would be more of a safety concern because of terrain and an adjacent airport (HAR Int)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wOvUB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wOvUB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2882" LastEditorUserId="167" LastEditDate="2016-01-13T03:55:02.877" LastActivityDate="2017-06-18T00:45:20.573" Title="Why is radar required on some FAA instrument approaches?" Tags="&lt;instrument-flight-rules&gt;&lt;faa&gt;&lt;approach&gt;&lt;non-precision-approach&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23869" PostTypeId="1" AcceptedAnswerId="23895" CreationDate="2015-12-23T02:46:03.057" Score="9" ViewCount="1655" Body="&lt;p&gt;While looking at the various instrument approaches for Napa Valley (KAPC), I noticed a discrepancy between the RNAV (GPS) Y/Z RWY36L missed approaches and the ILS/LOC RWY36L approach:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GNKzC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GNKzC.jpg&quot; alt=&quot;annotated KAPC ILS36L plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PiwVF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PiwVF.jpg&quot; alt=&quot;annotated KAPC RY36L plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RFBoP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RFBoP.jpg&quot; alt=&quot;annotated KAPC RZ36L plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it that the ILS approach is able to use a turning missed approach to keep pilot and plane clear of the high ground to the north, but the RNAV approaches to the same runway force you to either have visual contact with the high ground early, or outclimb it?  To me, it'd make more sense to have the RNAV procedures use a similar missed approach to the ILS, as then you could have an all-aircraft RNAV procedure with low minima, vs. one with high minima that works for everyone and one with low minima that requires a significant (more than twice the norm) missed approach climb rate.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2015-12-23T03:11:55.393" LastActivityDate="2017-12-17T05:11:18.003" Title="Why do the RNAV (GPS) approaches to KAPC not use the same missed approach procedure as the ILS/LOC approach?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;&lt;terps&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23870" PostTypeId="2" ParentId="23869" CreationDate="2015-12-23T03:02:11.973" Score="1" Body="&lt;p&gt;Look at where the missed approach points are on each approach. The ILS has you very low, and possibly unable to clear the terrain to the northeast, hence the turning procedure. The RNAV has you going missed almost 1000 feet above the ILS, so terrain clearance would not be as much of a factor. For either ATC or convenience reasons they probably prefer you to go missed to the north east, hence they have the RNAV go that way. &lt;/p&gt;&#xA;" OwnerUserId="12755" LastActivityDate="2015-12-23T03:02:11.973" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23871" PostTypeId="1" CreationDate="2015-12-23T06:30:09.547" Score="2" ViewCount="1590" Body="&lt;p&gt;At one point I held a mechanic's certificate. However due to poor judgement it(the certificate) was revoked due to a narcotics conviction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can I get it reinstated? Is there refresher classes?&lt;/p&gt;&#xA;" OwnerUserId="12756" LastEditorUserId="62" LastEditDate="2017-01-04T15:38:10.210" LastActivityDate="2019-12-04T16:49:53.210" Title="What are the procedures to get a revoked mechanics certificate reinstated?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23872" PostTypeId="1" CreationDate="2015-12-23T08:39:22.773" Score="0" ViewCount="291" Body="&lt;p&gt;I want to install a big PTZ camera at the exterior of the plane like A380 which can give the pilot a clear view while landing or taxing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have gone through a similar question but it doesn't give any specific answer though. &lt;a href=&quot;https://aviation.stackexchange.com/questions/96/can-i-attach-a-camera-to-the-outside-of-my-aircraft-in-the-usa&quot;&gt;Can I attach a camera to the outside of my aircraft in the USA?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: if its going to be a permanent part of the aircraft and not a GoPro type, can it be included by the Manufacturer themselves?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not sure if this kind of exterior object is going to affect the aerodynamics of the plane. I got confused when an aerospace engineer told me it can affect the plane and can create some issues whilst in the air. &#xA;I would like to get clarification on this matter.&lt;/p&gt;&#xA;" OwnerUserId="5694" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2015-12-23T10:40:27.280" Title="Does installing a PTZ dome camera outside the aircraft violate any FAA rules?" Tags="&lt;fuselage&gt;&lt;camera&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23874" PostTypeId="2" ParentId="23871" CreationDate="2015-12-23T10:09:43.440" Score="7" Body="&lt;p&gt;I think you've to apply for a certificate again after the required period and take the tests again. From &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=4128757e254de87854acaaa4090010b9;rgn=div5;view=text;node=14%3A2.0.1.1.4;idno=14;cc=ecfr#se14.2.65_111&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §65.11 Application and issue&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(d) Unless the order of revocation provides otherwise—&lt;/p&gt;&#xA;&lt;p&gt;(2) A person whose mechanic or repairman certificate is revoked may not apply for either of those kinds of certificates for 1 year after the date of revocation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In your case, you have to wait for 1 year after the &lt;em&gt;final&lt;/em&gt; conviction to apply. From &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;sid=4128757e254de87854acaaa4090010b9;rgn=div5;view=text;node=14%3A2.0.1.1.4;idno=14;cc=ecfr#se14.2.65_112&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §65.12 Offenses involving alcohol or drugs&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) A conviction for the violation of any Federal or state statute relating to the growing, processing, manufacture, sale, disposition, possession, transportation, or importation of narcotic drugs, marihuana, or depressant or stimulant drugs or substances is grounds for—&lt;/p&gt;&#xA;&lt;p&gt;(1) Denial of an application for any certificate or rating issued under this part for a period of up to 1 year after the date of final conviction;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-23T10:09:43.440" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23875" PostTypeId="2" ParentId="23872" CreationDate="2015-12-23T10:40:27.280" Score="4" Body="&lt;p&gt;Aircraft out there already use external cameras for use during taxiing/landing. Airbus uses a system called external and taxiing aid camera system (Etacs) in A380 and A350, which uses three cameras:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;One camera in nosewheel well gives a view towards the aircraft’s nose gear.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A second camera mounted on the vertical tail gives a high overview of the aircraft from the tail.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another camera is situated on the belly of the aircraft for giving views of runway below. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that both of these are FAA certified and under operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether or the camera affects the aircraft performance depends on the aircraft and the camera used (and installation location), though in most cases it shouldn't. In that case, you may have to get a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5;node=14%3A1.0.1.3.9#sp14.1.21.e&quot; rel=&quot;nofollow&quot;&gt;supplementary type certificate&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-23T10:40:27.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23876" PostTypeId="2" ParentId="23867" CreationDate="2015-12-23T12:20:14.393" Score="10" Body="&lt;p&gt;Radar is most likely required in this case because there is no defined Initial Approach Fix (IAF). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that in the profile view TIVNE and HORVI have the word RADAR underneath, which means that if you wanted to fly to either of those way points, including a course reversal in the hold, you would still need to be vectored by ATC via RADAR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that ATC needs to give vectors to final or otherwise provide a specific clearance to establish an IFR aircraft on the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be other considerations, but that is the main one that I see here.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="3504" LastEditDate="2016-01-12T19:24:01.003" LastActivityDate="2016-01-12T19:24:01.003" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23879" PostTypeId="1" CreationDate="2015-12-23T13:07:36.737" Score="2" ViewCount="129" Body="&lt;p&gt;Very much a hypothetical question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At Trondheim a few days ago we had quite a long, fast (to my experience) pushback: now obviously we didn't hit anything close to Vr, but it started me wondering if an airliner could theoretically fly in reverse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say for the sake of argument that we flipped the engines round without introducing any other problems, and stuck a window in the tail with a seat, controls and flight instruments in front of it... then put the plane on a runway and tried to take off. Would the airfoil allow the aircraft to take off? Would it be in any way controllable? Obviously I'm not expecting the plane to be flyable by a pilot, merely curious if it's theoretically possible aerodynamically (perhaps computer controlled).&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-12-23T13:07:36.737" Title="Could an airliner (in theory) fly truly &quot;backwards&quot;?" Tags="&lt;aerodynamics&gt;&lt;airliner&gt;&lt;control-surfaces&gt;&lt;hypotheticals&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="1" ClosedDate="2015-12-23T14:53:03.023" ContentLicense="CC BY-SA 3.0" />
  <row Id="23880" PostTypeId="2" ParentId="23867" CreationDate="2015-12-23T15:30:48.950" Score="1" Body="&lt;p&gt;From the &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/chapter_4.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA's hand book on IFR flying (page 4-17)&lt;/a&gt;. It seems that it is the minimum equipment required to fly the approach. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In some cases, other types of navigation systems, including radar, are&#xA;  required to execute other portions of the approach or to navigate to&#xA;  the IAF (for example, an NDB procedure turn to an ILS, or an NDB in&#xA;  the missed approach, or radar required to join the procedure or&#xA;  identify a fix). When ATC radar or other equipment is required for&#xA;  procedure entry from the en route environment, a note is charted in&#xA;  the plan view of the approach procedure chart (for example, RADAR&#xA;  REQUIRED or AUTOMATIC DIRECTION FINDER (ADF) REQUIRED). When radar or&#xA;  other equipment is required on portions of the procedure outside the&#xA;  final approach segment, including the missed approach, a note is&#xA;  charted in the notes box of the pilot briefing portion of the approach&#xA;  chart (for example, RADAR REQUIRED or DISTANCE MEASURING EQUIPMENT&#xA;  (DME) REQUIRED). Notes are not charted when VOR is required outside&#xA;  the final approach segment. Pilots should ensure that the aircraft is&#xA;  equipped with the required NAVAIDs to execute the approach, including&#xA;  the missed approach. Refer to the AIM paragraph 5-4-5 for additional&#xA;  options with regards to equipment requirements for IAPs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Later on they talk about Radar Approaches (Page 4-71)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two types of radar approaches available to pilots when operating&#xA;  in the NAS are precision approach radar (PAR) and airport surveillance&#xA;  radar (ASR). Radar approaches may be given to any aircraft at the&#xA;  pilot’s request. ATC may also offer radar approach options to aircraft&#xA;  in distress regardless of the weather conditions or as necessary to&#xA;  expedite traffic. Despite the control exercised by ATC in a radar&#xA;  approach environment, it remains the pilot’s responsibility to ensure&#xA;  the approach and landing minimums listed for the approach are&#xA;  appropriate for the existing weather conditions considering personal&#xA;  approach criteria certification and company OpSpecs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They can also be useful in helping disabled aircraft in (page 4-74). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Perhaps the greatest benefit of either type of radar approach is the&#xA;  ability to use radar to execute a no gyro approach. Assuming standard&#xA;  rate turns, ATC can indicate when to begin and end turns. If&#xA;  available, pilots should make use of this approach when the heading&#xA;  indicator has failed and partial panel instrument flying is required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2015-12-23T15:30:48.950" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23881" PostTypeId="1" CreationDate="2015-12-23T18:44:32.187" Score="29" ViewCount="8858" Body="&lt;p&gt;What does the crosshatched area on an altimeter tell you?  It's only visible when below 10,000 ft indicated altitude.  Can't be terrain awareness, a lot of terrain around here is over 10,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This sample altimeter display from the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA manual on flight instruments&lt;/a&gt; shows the crosshatched area:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cVXGy.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cVXGy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the accompanying text from the manual where it points out the crosshatched area:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Crosshatch flag:&lt;/strong&gt; A crosshatched area appears on some altimeters when displaying an altitude below 10,000 feet MSL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12764" LastEditorUserId="19" LastEditDate="2016-06-30T16:57:19.520" LastActivityDate="2020-01-29T20:53:45.443" Title="What is the meaning of the crosshatch marking on altimeters?" Tags="&lt;altimeter&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23883" PostTypeId="1" AcceptedAnswerId="23888" CreationDate="2015-12-23T20:22:00.410" Score="23" ViewCount="2716" Body="&lt;p&gt;A Southwest airliner recently &lt;a href=&quot;http://www.mercurynews.com/news/ci_29303252/southwest-flight-reports-mechanical-problem-after-taking-off&quot;&gt;had an issue&lt;/a&gt; where a &quot;deflated tire indicator&quot; showed on one of the landing gear tires after takeoff from Oakland, CA. They circled nearby for 4 hours while burning off fuel before landing back at Oakland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a circumstance like that, where there's no flight control or aerodynamic problem (i.e. landing gear door stuck open), why wouldn't the flight continue on to the destination airport and burn fuel along the way? The flight time is close to the amount of time they spent circling to burn off fuel, so it's not like they get on the ground any faster by staying near their source airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this particular plane landed safely and inspection showed no indication of any real issue with the tire, but even if it did have a flat tire, would it be any worse to go on to the destination?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect that it may be just in case another in-flight emergency forces the plane to divert to an alternate airport that may not have the full emergency equipment to deal with a landing gear problem, which raises the question: if the flight had departed from a small airport with limited emergency support, would the plane travel to an alternate airport with better emergency support?&lt;/p&gt;&#xA;" OwnerUserId="1844" LastEditorUserId="7532" LastEditDate="2015-12-26T02:50:59.793" LastActivityDate="2015-12-26T02:50:59.793" Title="Why burn fuel at departure airport instead of flying to destination before emergency landing due to deflated tire?" Tags="&lt;emergency&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23884" PostTypeId="2" ParentId="23869" CreationDate="2015-12-23T21:17:10.270" Score="1" Body="&lt;p&gt;GPS approaches and missed approach routing are designed point to point to point, so &quot;climb to XXX then direct ABC&quot; doesn't work -- there is no defined track to sequence to after the straight-ahead leg. So the GPS approaches can't use the same procudure as the ILS does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There does seem to be a terrain or obstacle issue somewhere on the missed approach routing of the GPS approaches. So you can either fly the &quot;Y&quot; approach with a high MDA (so you start the missed approach higher, with less altitude needed to clear the obstacle), or you can fly the &quot;Z&quot; approach that takes you lower but requires a higher than standard missed approach climb gradient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is probably a reason that the approach designer didn't use a missed approach track that would look more like the ILS missed approach track (but done point to point to point), avoiding the obstacle even with a normal climb gradient, but we can't tell what that reason is. A minimum length of each segment and similar TERPS criteria would be my guess, but that is only a guess.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-23T21:17:10.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23885" PostTypeId="2" ParentId="23883" CreationDate="2015-12-23T21:33:01.500" Score="14" Body="&lt;p&gt;I have no idea what a deflated tire indication is on a 737, but perhaps the news media got something wrong in their reporting. (Nah... that &lt;em&gt;never&lt;/em&gt; happens, does it???)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, the cardinal rule of landing gear problems is to leave a good configuration alone, so don't retract a gear with a possible problem, since it might not come back down again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the landing gear extended, your fuel burn per mile is far greater than with the gear up, so &quot;enough fuel to get to XYZ&quot; (based on normal gear-up cruise) isn't nearly enough to get there with the wheels down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any time an airliner takes off from a field they couldn't return to (most often, this comes up because the weather isn't good enough for a published approach back in), they have a &quot;takeoff alternate&quot; that they could get in to within a prescribed distance -- typically an hour's flying time.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="1696" LastEditDate="2015-12-24T00:40:22.673" LastActivityDate="2015-12-24T00:40:22.673" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23886" PostTypeId="2" ParentId="23881" CreationDate="2015-12-23T21:37:28.377" Score="11" Body="&lt;p&gt;It replaces to 10 thousands digit, evidently because X9000 has been found to be easier to read than 09000 or just blank space before the 9000. That crosshatched area would also scroll to display &quot;NEG&quot; if the altimeter is displaying an altitude below zero feet (i.e. Below sea level or below the reference datum plane).&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-23T21:37:28.377" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23887" PostTypeId="1" CreationDate="2015-12-23T23:54:15.973" Score="9" ViewCount="2497" Body="&lt;p&gt;When airports fall behind traffic for some reason and delays piling up, how do they catch up? If flights need to be cancelled, who decides (and when) - ATC, airport management, or airlines themselves?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an illustration, here is a snapshot from &lt;a href=&quot;https://flightaware.com/live/airport/delays&quot;&gt;this page&lt;/a&gt; (taken at approx. 2355 UTC 12/23/15):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1zVl8.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1zVl8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-12-24T21:25:28.737" Title="How does an airport catch up when it is behind on traffic?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23888" PostTypeId="2" ParentId="23883" CreationDate="2015-12-24T00:29:40.167" Score="13" Body="&lt;p&gt;The issue here is threefold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What exactly has happened? Has one tire simply deflated? Or more than one gone?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Has some other problem happened due to the event that led to tire deflation?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you have a damaged tire during takeoff, you have one during landing and that is not a very good thing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A tire deflation may indicate many things- one of the tires may have deflated  or the tread may have given way, leading to debris (which will force a runway check)and damage. It is best to be cautious and asses the damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there may be other damages to the aircraft (if for example, the tread has been damaged) which may manifest later on. For example, &lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/GB/2004-09-01-UK.pdf&quot;&gt;in a Boeing 737&lt;/a&gt;, tire failure lead to,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... the loss of the A system hydraulic contents, failure of the landing gear to retract...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tyre debris had been flung upward and rearward, becoming lodged against the left rear spar close to aileron and spoiler control cables..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unless you know for sure, it is better not to continue with the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjUh-2emvPJAhVDA44KHf8_DNQQFggbMAA&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DB737-Tire_Failures.pdf&amp;amp;usg=AFQjCNE2PBDhLdV7wyczDO5SA1tMkx_j3g&amp;amp;bvm=bv.110151844,d.c2E&quot;&gt;this document&lt;/a&gt; that clearly says that in case of tire failure in takeoff (though I'm not sure how 'official' it is):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Always think twice before retracting gear and then flaps.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, landing with a burst tire will cause:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Possible loss of braking effectiveness&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Difficulty in directional control during landing&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;among others. Better to be land back in the same airport rather getting diverted to an unknown airport which may or may not have the required facilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, the decision to return to the same airport or continuing on is the captain's decision. for example, the captain of the B737 already referred &lt;em&gt;declined&lt;/em&gt; to return to the airport (at first, anyway) though offered by the ATC.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-24T00:41:05.997" LastActivityDate="2015-12-24T00:41:05.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23889" PostTypeId="2" ParentId="21981" CreationDate="2015-12-24T01:13:00.490" Score="98" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If you're interested in a more visual, and less technical, explanation of Space Shuttle reentry and landing, I gave a talk titled &lt;a href=&quot;https://www.youtube.com/watch?v=Jb4prVsXkZU&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;How to Land the Space Shuttle... from Space&lt;/strong&gt;&lt;/a&gt; at the Stack Overflow meetup in October 2016.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I didn't notice this question until a couple of days ago, but as someone with an unhealthy obsession with &lt;em&gt;specifically&lt;/em&gt; the entry and landing phases of shuttle flights, I can say there is &lt;em&gt;a lot&lt;/em&gt; of factually incorrect information in the other answers here. Let me see if I can explain it better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the two easy questions, which were answered well by other questions, but I'll include here as well for completeness:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Could the shuttle perform a go-around?&lt;/strong&gt; No. The OMS engines are too weak to make a difference in the atmosphere, and the main engines (which &lt;em&gt;would&lt;/em&gt; be powerful enough) are only fueled by the orange external tank which is jettisoned after launch.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Where did it land?&lt;/strong&gt; 78 missions landed at the Kennedy Space Center, 54 (including the first) at &lt;a href=&quot;https://en.wikipedia.org/wiki/Edwards_Air_Force_Base&quot; rel=&quot;noreferrer&quot;&gt;Edwards Air Force Base&lt;/a&gt;, and 1 at &lt;a href=&quot;https://en.wikipedia.org/wiki/White_Sands_Space_Harbor&quot; rel=&quot;noreferrer&quot;&gt;White Sands&lt;/a&gt;. There were other landing sites designated for emergencies, but none were ever used.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, for the &lt;em&gt;really&lt;/em&gt; big question of how the shuttle reentered and landed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The primary source I'm going to cite in this answer is the &lt;em&gt;Entry, TAEM, and Approach/Landing Guidance Workbook 21002&lt;/em&gt; which was a workbook used for training astronauts. Sadly, I don't have a link to it, but it can be obtained from &lt;a href=&quot;http://www.nasaspaceflight.com/&quot; rel=&quot;noreferrer&quot;&gt;nasaspaceflight.com&lt;/a&gt; via an &lt;a href=&quot;http://www.nasaspaceflight.com/l2/&quot; rel=&quot;noreferrer&quot;&gt;L2 subscription&lt;/a&gt; if you're really interested. I'm going to abreviate this source as &lt;em&gt;ETAGW&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Orbital Mechanics&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First, a &lt;em&gt;real quick&lt;/em&gt; lesson in orbital mechanics. In order to change the altitude of your orbit you make a change in velocity ($\Delta v$). If you increase velocity, you'll increase altitude, and if you decrease velocity, you'll decrease altitude. However, this effect is most pronounced 180° from the position where you made the change. After a complete 360° orbit, you'll be at approximately the same altitude you started at.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This illustrates the effect:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vHwzo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vHwzo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting from the circular orbit (black), if you slow down at point A, you might end up with something like the red orbit, and if you speed up you might end up with something like the blue orbit.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Deorbit Burn&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Because of the nature of orbital mechanics, as described above, you want to perform your deorbit maneuver on the opposite side of the planet from your intended landing site. This typically occurred over the Indian Ocean for a landing at Kennedy Space Center in Florida.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The burn itself was performed with the shuttle flying tail first and white (top) side facing towards the Earth (heat shield/black side facing towards space). The two OMS (orbital maneuvering system) engines were used to accomplish the required $\Delta v$ (anywhere between 200 and 550 ft/sec depending on the starting altitude). The burn typically took around 2.5 to 3 minutes. This would lower the perigee (lowest point in an orbit around Earth) to within a few miles of the ground (having a hard time finding a source, but I seem to remember it being around 30-40 miles), which was enough to ensure the orbital path would take them into thick atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X5HiZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X5HiZ.png&quot; alt=&quot;&quot;&gt;&lt;/a&gt; &lt;sup&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:STS-116_Shuttle_Engines.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The OMS engines are essentially larger versions of &lt;a href=&quot;https://en.wikipedia.org/wiki/Reaction_control_system&quot; rel=&quot;noreferrer&quot;&gt;RCS&lt;/a&gt; (reaction control system) jets. RCS jets were used for rotation (attitude) and small translation (velocity in a given direction) changes. The OMS were used for making orbital changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both systems burned the same &lt;a href=&quot;https://en.wikipedia.org/wiki/Hypergolic_propellant&quot; rel=&quot;noreferrer&quot;&gt;hypergolic&lt;/a&gt; mixture (monomethylhydrazine (MMH) and dinitrogen tetroxide (N2O4)). If the OMS had failed, the RCS jets could have, in theory, been used to slow the shuttle enough for reentry.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Nose Flip&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some answers have said that the orbiter would pitch &lt;em&gt;down&lt;/em&gt; 140° for the flip. This is incorrect. After the deorbit maneuver was completed, the orbiter would pitch &lt;em&gt;up&lt;/em&gt; about 220° until it reached a 40° nose-up angle of attack (referred to as the &quot;EI -5 attitude&quot; because they must be in that attitude by at least five minutes prior to entry interface).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They have about 20 minutes between the deorbit burn and EI-5, so there's plenty of time to pitch in either direction. Nose &lt;em&gt;up&lt;/em&gt; was likely preferred because the &lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit#Spacecraft&quot; rel=&quot;noreferrer&quot;&gt;APU&lt;/a&gt; exhaust vents point up near the tail. This naturally causes the orbiter to want to pitch up when the APUs are running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During this pitch-up, they would fire the &lt;em&gt;forward&lt;/em&gt; RCS jets to dump all the forward fuel, unless it was required for center-of-gravity reasons. The forward RCS jets weren't used during reentry, and dumping the fuel reduces potential hazards to the astronauts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once in position, open-loop entry guidance would begin, holding the orbiter at 0° roll (wings level), 0° yaw, and 40° angle of attack (alpha).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Entry Interface&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;NASA defines the entry-interface (EI) as an altitude of 400,000 feet. There's no hard-edge to the atmosphere, but this is around the altitude where its effects start to become directly detectable.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;S-Turns&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Some answers have claimed that the shuttle used S-turns for the purpose of slowing down. This is a very common, but over-simplified and arguably inaccurate, explanation.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The next time you hear someone talk about the shuttle doing roll reversals to bleed off energy, do not listen. &lt;em&gt;The shuttle does roll reversals because it has a very small alpha envelope.&lt;/em&gt;&quot; - &lt;em&gt;ETAGW&lt;/em&gt; 2.8.1 (emphasis is from original source)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As with any airplane, the shuttle's wings generate lift. As the atmosphere gets denser, the wings are going to generate more lift, and this upward lift will cause the descent rate to slow. In fact if the shuttle maintained a wings-level attitude, it would eventually start to &lt;em&gt;gain&lt;/em&gt; altitude causing it to &quot;skip&quot; across the atmosphere several times until it was slow enough to fall through. And while technically a skipping reentry would be possible, it would be very difficult to control with any precision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, instead, when the decent rate starts to slow, the shuttle goes into a bank. By controlling the bank angle, they're able to control how much upward lift the wings are generating, and, by extension, control their descent rate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5af3n.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5af3n.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;ETAGW Figure 2-5 illustrating lift vector.&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or course, with the lift vector pointed sideways instead of upwards, the shuttle is going to start to turn. Due to the incredible speed, the turn radius is enormous, but it does gradually turn nonetheless, and the orbiter develops an azimuth error (the difference between the orbiter's current direction and the direction to the landing site).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HawYf.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HawYf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;ETAGW Figure 2-3 illustrating azimuth error.&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To correct this azimuth error ($\Delta z$), the orbiter performs &quot;roll reversals&quot;. In other words, it turns in the other direction. These turns create the distinctive S-turn reentry track.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first reversal always occurs at 10.5° $\Delta z$. Subsequent reversals occur at 17.5° until Mach 4 when it starts ramping down to 10° at Mach 3.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note: all mach numbers given anywhere in this answer, or referenced anywhere in Space Shuttle materials, aren't true mach numbers. NASA uses 1000 ft/sec as an approximation of Mach 1, and all mach numbers are multiples of that velocity.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Ranging&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Obviously, the ultimate goal of reentry is to reach your intended runway at an appropriate speed for landing. While the orbiter doesn't have any engines to help accomplish this, it does have a tremendous amount of orbital energy. Therefore the goal becomes energy management, and more specifically, drag management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The orbiter has two ways to affect drag during entry: changing angle of attack (alpha), and changing bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Angle of attack is the quickest way to increase or decrease drag, but the orbiter was only allowed to deviate ±3° from the nominal alpha (40° for most of entry). This is the &quot;very small alpha envelope&quot; referred to earlier. The limitation is designed to ensure proper heat protection and maintain vehicle control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing bank angle, as described above, allows you to control your descent rate. A steeper bank angle will result in reaching thicker air faster, and will therefore result in increased drag. A shallower bank angle will keep the orbiter in thinner air for longer, and result in less drag. However, it takes a little longer to see the effect of a bank change than an alpha change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also bank angle limitations because, again, you don't want to skip out of the atmosphere, and you don't want to fall into thick air so fast that it exceeds the maximum drag the vehicle can handle, but it is a larger envelope than the alpha limits. In fact, in early stages of entry, the orbiter could have even flown upside down (with its lift vector pointed towards Earth) if necessary due to an under-burn as the result of a malfunction during the deorbit burn.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Entry Guidance Phases&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I'm not going to go into detail about entry guidance, but I will say that the primary considerations change as speed and altitude changes, and the entry guidance is broken up into phases to reflect this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SJb90.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SJb90.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;ETAGW&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the chart above, the middle line represents the nominal profile. The lowest line is the &quot;equilibrium glide&quot; profile which is the minimum amount of drag that the orbiter must maintain to avoid gaining altitude and skipping. The line at the top left represents a thermal limit (if the orbiter exceeds it, it might burn up). The line at the upper right represents a dynamic pressure limit (if the orbiter exceeds it, it might break up due to aerodynamic forces).&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Preentry&lt;/strong&gt;: This is considered open-loop guidance because all it does it maintain 0° yaw, 0° roll, and 40° alpha until the total load factor becomes 0.132g (approximately 3 ft/sec&lt;sup&gt;2&lt;/sup&gt; of drag), at which point closed-loop guidance begins.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Temperature Control&lt;/strong&gt;: Begins at closed loop guidance and ends at a velocity of Mach 19. Tries to maintain a constant temperature within the design limits of the orbiter.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Equilibrium Glide&lt;/strong&gt;: Simply provides a bridge between temperature control and constant drag phases. It ends when drag reaches 33 ft/sec&lt;sup&gt;2&lt;/sup&gt;. It's named as such because its shape is similar to that of the equilibrium glide profile.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Constant Drag&lt;/strong&gt;: Maintains a constant drag rate of 33 ft/sec&lt;sup&gt;2&lt;/sup&gt; until velocity reaches Mach 10.5.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Transition&lt;/strong&gt;: Designed to transition from the high drag and high alpha of entry to the lower drag and lower alpha required for the orbiter to fly more like an airplane. This phase terminates at Mach 2.5 when TAEM begins.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;TAEM&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;TAEM stands for Terminal Area Energy Management. The objective in this stage is to get the orbiter lined up with the runway with the correct amount of energy to make its final approach. Again, I'm not going to go into a ton of detail (feel free to ask other questions if you want), but here's the gist:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all went well in the entry stage, TAEM will begin at about 82,000 feet and 60 nautical miles from the runway (intended ground track, not straight-line distance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whereas Entry guidance primarily uses bank angle to manage energy, TAEM primarily uses angle of attack. Below Mach 1, the speedbrake (a split rudder) also helps with energy management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UyyU5.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UyyU5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;Source: &lt;a href=&quot;http://www.nasa.gov/centers/dryden/news/X-Press/stories/2004/063004/Popups/STS_speed_brake.html&quot; rel=&quot;noreferrer&quot;&gt;NASA&lt;/a&gt;&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Phases of TAEM:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;S-Turn&lt;/strong&gt;: Usually not required, but the shuttle will perform S-turns if it is too high on energy at the start of TAEM (too high, or too close to the runway).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Acquisition&lt;/strong&gt;: Turns the orbiter towards a point of tangency on the heading alignment cone (HAC) and then flys wings-level until it intercepts the HAC. The tangency point is referred to as &quot;waypoint 1&quot; (WP1). During this phase, the orbiter slows to below Mach 1, at which point the commander takes CSS (control-stick steering), which is the closest thing the shuttle has to a &quot;manual&quot; mode.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Heading Alignment&lt;/strong&gt;: Guides the orbiter around a virtual &quot;cone&quot; (see diagram below) until it is in alignment with the runway. It's not &lt;em&gt;really&lt;/em&gt; a cone, mathematically speaking, but it's the easiest way to visualize it.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Prefinal&lt;/strong&gt;: Establishes the orbiter on the outer glide slope.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cFbtJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cFbtJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;ETAGW Figure 3-13 illustrating the HAC.&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Approach and Landing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The final guidance phase is called &quot;Approach and Landing&quot;. It begins when the orbiter is below 10,000 feet and established on the outer glide slope (OGS), but no later than 5000 feet regardless of glide slope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The OGS was a 20° glide slope for &quot;light&quot; orbiters (gross weight less than 222,000 pounds) or 18° for &quot;heavy&quot; orbiters (by comparison, normal airplanes use a 3° glide slope). Heavy or light depended on what was in the payload bay. The nominal aim point for the OGS was 7500 feet short of the runway threshold, but there was also a &quot;close-in&quot; aim point at 6500 feet which was used in the event of a strong enough headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The speed brake was used to maintain 300 KEAS (&lt;a href=&quot;https://en.wikipedia.org/wiki/Equivalent_airspeed&quot; rel=&quot;noreferrer&quot;&gt;knots equivalent airspeed&lt;/a&gt; - it's effectively the same as indicated airspeed) on the OGS until 3000 feet, at which time it calculated how much speed brake should be required for landing, and moved to that position. It would re-calculate once more at 500 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At 2000 feet, the orbiter would begin a &quot;preflare&quot; maneuver designed to transition from the OGS to the shallow 1.5° inner glide slope (IGS). This was accomplished with a circular pull-up followed by an exponential decay onto the IGS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vcirr.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vcirr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;em&gt;ETAGW Figure 4-8 illustrating the preflare geometry.&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, the IGS is not followed for long, and is more of a guide for making sure you cross the runway threshold on the proper trajectory and get into position to begin the final flare, which is essentially the same as a conventional landing flare in a normal aircraft, except that the shuttle lands at a much higher angle of attack (about 8°) due to its delta wings (more similar to Concorde).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing gear was deployed at 300 feet, and if you're interested in landing gear, I wrote a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1109/did-the-space-shuttle-really-wait-until-50-feet-above-the-ground-before-they-put/1126#1126&quot;&gt;whole answer on landing gear deployment&lt;/a&gt; once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The targeted touchdown point was 2500 feet down the runway at an airspeed of 195 knots for light orbiters, or 205 knots for heavy (within +5/-10 knots).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The drag chute (an addition made in the early 90's) would be deployed shortly after main gear touchdown, but not faster than 195 knots, and sometimes they would wait until nose gear touchdown if there was a crosswind. It would be jettisoned at 60 knots to ensure the chute attachment mechanism didn't hit and damage the main engines.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Control&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;(e.g. how was the shuttle able to make attitude changes?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In early entry, the orbiter is still controlled like a spacecraft, using RCS jets to control attitude. As dynamic pressure (q-bar) increases, the aerodynamic surfaces begin to become active and the RCS jets shutdown as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;q-bar = 0.5 pounds/ft&lt;sup&gt;2&lt;/sup&gt; (psf), the &lt;a href=&quot;https://en.wikipedia.org/wiki/Elevon&quot; rel=&quot;noreferrer&quot;&gt;elevons&lt;/a&gt; begin to act as trim.&lt;/li&gt;&#xA;&lt;li&gt;q-bar = 2 psf, elevons begin to act as active control surfaces.&lt;/li&gt;&#xA;&lt;li&gt;q-bar = 10 psf, RCS roll jets are disabled.&lt;/li&gt;&#xA;&lt;li&gt;q-bar = 40 psf, RCS pitch jets are disabled.&lt;/li&gt;&#xA;&lt;li&gt;Mach 10, the speedbrake opens on a pre-programmed schedule to act as pitch trim.&lt;/li&gt;&#xA;&lt;li&gt;Mach 5, rudder becomes active, initially acting primarily as aileron trim.&lt;/li&gt;&#xA;&lt;li&gt;Mach 1, RCS yaw jets are disabled.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Navigation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;(e.g. how did the shuttle know where it was at?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Navigation, in NASA terms, basically means knowing where you are (guidance answers the question &quot;how do I get where I want to go?&quot;). During entry, the shuttle primarily used &lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;noreferrer&quot;&gt;inertial navigation units&lt;/a&gt;, which were aligned using a &lt;a href=&quot;https://en.wikipedia.org/wiki/Star_tracker&quot; rel=&quot;noreferrer&quot;&gt;star tracker&lt;/a&gt; prior to the deorbit burn. As it got closer to the landing site it could also incorporate GPS and/or &lt;a href=&quot;https://en.wikipedia.org/wiki/Tactical_air_navigation_system&quot; rel=&quot;noreferrer&quot;&gt;TACAN&lt;/a&gt; signals into the nav data. OV-105 (aka Space Shuttle Endeavor) had a three GPS units installed and no TACANs, whereas the other orbiters had three TACANs and one GPS unit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the HAC, anywhere from about 15k to 20k feet in altitude, the orbiter would pick up the microwave landing system (MLS), which acts sort of like a very high precision ILS. From this, they're able to determine their position with high precision and accuracy. Once acquired, this becomes the primary source of nav data for the remainder of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On landing videos, you can actually see exactly when they pick up MLS because the altitude tape goes from being sort of jerky, then jumps a little bit and becomes smooth. For example, &lt;a href=&quot;https://youtu.be/KBTqtZIGV6U?t=28m28s&quot; rel=&quot;noreferrer&quot;&gt;watch here&lt;/a&gt; at about the 20k mark (altitude tape is the one on the right).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below 5000 feet, the orbiter was also able to use a radar altimeter for altitude information.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That's probably more information than you were looking for, but if you have questions about things I didn't cover, or didn't go into enough detail on, feel free to ask separate questions for those.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-11-07T00:05:08.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23890" PostTypeId="1" AcceptedAnswerId="23903" CreationDate="2015-12-24T01:26:04.700" Score="8" ViewCount="2167" Body="&lt;p&gt;I understand constant speed propellers and beta range. However, I'm not completely sure I'm extracting everything from this chart that appears in a manual for a flight sim model of the Twin Otter. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is this format common for describing propeller range in aviation?&lt;/li&gt;&#xA;&lt;li&gt;Can someone describe the information exposed by the chart in words?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/A75gy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/A75gy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source - Aerosoft manual&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="22726" LastEditDate="2019-03-04T04:57:13.147" LastActivityDate="2019-08-30T05:17:40.990" Title="How to read the propeller range chart for DHC-6 Twin Otter?" Tags="&lt;constant-speed-propeller&gt;&lt;dhc-6&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23892" PostTypeId="2" ParentId="23887" CreationDate="2015-12-24T02:27:20.210" Score="5" Body="&lt;p&gt;Well, the delays usually pile up during the busy hours. They manage to eliminate the delay times when the flights arrive or land at the non-busy hours which dissipates most of the delays. One or two flight cancellations won't have much impact on the departure or arrival time during busy hours because the airport is packed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This situation is very similar to rush hour traffic on roadways dissapating after those hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your second question, it is mostly airlines that cancel their flights. Airport management might cancel a flight if there is something really wrong with it. and ATC might cancel if the weather or some other occasion warrants it.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-12-24T02:27:20.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23893" PostTypeId="2" ParentId="23881" CreationDate="2015-12-24T04:12:51.860" Score="13" Body="&lt;p&gt;It looks like the crosshatch (or &lt;a href=&quot;https://en.wikipedia.org/wiki/Barber&amp;#39;s_pole#Aviation_and_space_flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;barber pole&lt;/a&gt;) indicator doesn't have a consistent meaning (a similar marking is used on &lt;a href=&quot;https://www.google.com/search?q=airspeed%20indicator%20barber%20pole&amp;amp;ie=utf-8&amp;amp;oe=utf-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;some airspeed indicators&lt;/a&gt;, by the way). I found several different examples of when it can appear:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Below 10,000' (&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA PHAK&lt;/a&gt;; &lt;a href=&quot;https://books.google.com/books?id=Y3g-AAAAYAAJ&amp;amp;pg=SA2-PA70&amp;amp;lpg=SA2-PA70&amp;amp;dq=aircraft%20altimeter%20display%20%20stripes&amp;amp;source=bl&amp;amp;ots=EvJkUlNPZm&amp;amp;sig=IJlQUiMhQItvR5AtlC6_uGmKASA&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwiB2rKsy_PJAhXL2R4KHXpADRQQ6AEINDAE#v=onepage&amp;amp;q=aircraft%20altimeter%20display%20%20stripes&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;Army RC-12H manual&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Below 15,000' (&lt;a href=&quot;http://www.centuryinstruments.net/Catalog1/page06.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;instrument service catalogue&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Below 16,000' (another &lt;a href=&quot;http://www.chiefaircraft.com/utd-5934pa3.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;instrument catalogue&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Above 0', i.e. above sea level (instrument repair &lt;a href=&quot;http://tghaviation.com/aircraft-instrument-services/tag/barber-pole/&quot; rel=&quot;nofollow noreferrer&quot;&gt;information&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The only source that gave any explanation is the &lt;a href=&quot;http://tghaviation.com/aircraft-instrument-services/tag/barber-pole/&quot; rel=&quot;nofollow noreferrer&quot;&gt;last one&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the altitude is below sea level the barber pole is no longer&#xA;  visible. This is provided to avoid the error of reading –1,000 Ft. as&#xA;  being +10,000 Ft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;After following a bunch of links and skimming some discussion forums, my conclusion is that @RalphJ is &lt;a href=&quot;https://aviation.stackexchange.com/a/23886/62&quot;&gt;probably right&lt;/a&gt;: manufacturers added the flag to highlight that the aircraft is at a relatively low altitude, in a way that's much easier and quicker for the pilot than 'parsing' multiple hands on the altimeter face. And the fact that different sources give different altitudes highlights an important point: it's always a good idea to read the handbook or manual for all your instruments because you can't assume that everything works the same way in every aircraft, even something as 'simple' as an altimeter.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-12-24T04:12:51.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23894" PostTypeId="1" AcceptedAnswerId="23897" CreationDate="2015-12-24T04:15:54.447" Score="16" ViewCount="2704" Body="&lt;p&gt;Just as military camouflage can be legally worn by civilians on most jurisdictions (e.g., in the U.S.), can I create a stealth aircraft for non-military use? More precisely, can I register and fly the thing?&lt;/p&gt;&#xA;" OwnerUserId="12769" LastEditorUserId="15311" LastEditDate="2017-12-23T15:47:38.570" LastActivityDate="2017-12-24T00:28:26.990" Title="Is it legal to make a non-military stealth plane?" Tags="&lt;aircraft-design&gt;&lt;faa-regulations&gt;&lt;military&gt;&lt;stealth&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="23895" PostTypeId="2" ParentId="23869" CreationDate="2015-12-24T04:59:01.077" Score="7" Body="&lt;p&gt;As best I can understand from the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8260.3B_Chgs_1-26_rev.pdf&quot;&gt;TERPS&lt;/a&gt;, it's because there are certain criteria for RNAV missed approaches that wouldn't be met by copying the ILS missed approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, I found the following (see chapters 7 and 15):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In RNAV missed approaches &quot;turns shall not exceed 120°&quot;, but the ILS missed approach requires about a 180° turn. There's some related information &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs420/acfipg/media/open/Hist_14-01-315.pdf&quot;&gt;here&lt;/a&gt; about the FAA testing turns greater than 120° in RNAV instrument procedures, it looks like some avionics can't handle them properly.&lt;/li&gt;&#xA;&lt;li&gt;RNAV missed approaches are made up of legs between waypoints, and the first leg after the MAP has a required minimum length &quot;to allow the aircraft's stabilization on course immediately after the MAP&quot;. Unfortunately I couldn't identify what that length is, because the FAA's PDF quality is abysmal and some information is unreadable, but the ILS missed approach requires a turn after a climb of less than 300' (from 214' to 500'), so the distance traveled in that time would presumably be quite small. If the RNAV minimum leg length is significantly greater than that distance, then it might be necessary to continue straight ahead, as both RNAV approaches do.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm certainly not a TERPS expert and there may well be other reasons for not using the ILS missed approach, but those two points seem to show that the criteria for designing missed approaches is different enough between procedure types that you can't just 're-use' them freely.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-24T04:59:01.077" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23896" PostTypeId="2" ParentId="16434" CreationDate="2015-12-24T05:19:12.607" Score="1" Body="&lt;p&gt;the real reason is tactical lighting.&#xA;not all russian aircraft have the turquoise/jade colors cockpits.&#xA;use red lights for tactical night operation, and very little light can be seen out from the cockpits.&#xA;russian helicopters and cargo that are design to operate in tactical night ops have also this feature.&lt;/p&gt;&#xA;" OwnerUserId="12770" LastActivityDate="2015-12-24T05:19:12.607" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23897" PostTypeId="2" ParentId="23894" CreationDate="2015-12-24T08:17:09.210" Score="21" Body="&lt;p&gt;Yes you may, but you need to carry a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_transponder_interrogation_modes#Mode_A_and_Mode_C&quot;&gt;mode C transponder&lt;/a&gt; while above 10,000 ft or in some types of &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Equipment/Transponder-Requirements&quot;&gt;controlled airspace&lt;/a&gt; and have it switched on. Which pretty much negates the stealth capabilities of your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To quote the linked AOPA page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to 14 CFR 99.13, no person may operate an aircraft into or&#xA;  out of the United States, or into, within, or across an ADIZ&#xA;  designated in subpart B unless operating a transponder with Mode C.&#xA;  Certain exemptions might apply to aircraft that were not originally&#xA;  certified with an engine-driven electrical system; see 99.13(d).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="12720" LastEditDate="2015-12-24T14:19:36.230" LastActivityDate="2015-12-24T14:19:36.230" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="23898" PostTypeId="2" ParentId="23735" CreationDate="2015-12-24T09:50:09.163" Score="-2" Body="&lt;p&gt;Interesting question: I remember having read long time ago, that Russian-built airliners tended being underpowered respect to their western counterparts, this resulting in slow climbing and other operational difficulties for air-traffic controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the USSR airplanes' instruments were metric; besides pilots say that feet are a bit more accurate in estimating height for things as precission landings, one meter is around three feet, also a mile is a minute of arch, no match between a km and arches, some problems resulted, for example, in places where metric units were used for fuel. For those having a local way for measurement, it's easier adapting to using it plus another more universal system than the reverse, from the general to the private, habitudes are hard to change&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Mars probe crashed when somebody mismatched metric and 'imperial' units in the software, an airliner had to make an emergency landing in an abandoned airstrip, this won the pilot an award, as he managed the no engine, gliding approach at a too high level, by sliding on the side. &#xA;The reason of this commercial jet running out of fuel was a mismatch between fuel supply units. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They said also that USSR jet engines were more fuel thirsty than their counterparts, perhaps due to the lack of access to the rare elements used for high temperature and stress alloys, this limiting the efficiency of engines.&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="3424" LastEditDate="2015-12-25T22:38:12.867" LastActivityDate="2015-12-25T22:38:12.867" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="23899" PostTypeId="1" CreationDate="2015-12-24T11:59:45.223" Score="3" ViewCount="1605" Body="&lt;p&gt;A specific example I'm referring to is Cathay Pacific's CX138 flight between Sydney and Hong Kong. This flight is scheduled to be 9 hours &amp;amp; 40 minutes long (departing SYD at 22:20 local time and arriving HKG at 05:00 local time) but in reality from Flightradar24 data, as well as having been on the flight, it seems that this flight consistently arrives around 03:45 to 04:00 average, which is a very early arrival. So why is the scheduled flight time so over-stated ? (Ironically, other CX flights between SYD &amp;amp; HKG at other times of the day have shorter scheduled flight times)&lt;/p&gt;&#xA;" OwnerUserId="11606" LastActivityDate="2015-12-25T23:42:19.730" Title="Why do airlines over-estimate/over-calculate flight times?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;boeing&gt;&lt;airlines&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23900" PostTypeId="2" ParentId="23899" CreationDate="2015-12-24T13:16:32.753" Score="4" Body="&lt;p&gt;Mainly, to improve their image. Though I'm not sure about this specific flight (or airline, for that matter), it appears that over estimating flight time is usual.&lt;/p&gt;&#xA;&lt;p&gt;For airlines it is better to overestimate the flight times and then claim that they are punctual, rather than correctly say the required time and then be late due to some unforeseen reasons. For example, if an airline says that a flight takes 80 minutes (while in reality, 60 minutes suffices) and then completes it in 70 minutes, the perception will be that the flight is early. After all, nobody is going to check the exact time required for flight.&lt;/p&gt;&#xA;&lt;p&gt;In general, the airlines would add some extra time to cater for things like tarmac congestion, holding time, connecting flight etc. However, it appears that the airlines are increasingly padding their 'block times' (which includes estimated flight time, taxi time at both ends, and time for short delays) in order to appear punctual.&lt;/p&gt;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.usatoday.com/story/travel/flights/2013/02/14/airlines-flights-early-arrivals/1921057/&quot; rel=&quot;nofollow noreferrer&quot;&gt;report by USAToday&lt;/a&gt; points out that (in US) more flights were arriving early than late (in 2012) and it appears that the trend remains the same. The report points out:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The average flight from Boston's Logan airport to New York's LaGuardia took one hour in 1995. In 2012, it took 75 minutes.&lt;/p&gt;&#xA;&lt;p&gt;Yet the Logan-to-LaGuardia early-arrival rate soared to 38% last year from just 2% in 1995 as Delta and US Airways added nearly 20 minutes to the schedule.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This makes the passengers think that the flights are on time, though they are actually late (when compared to earlier timing). For example, U.S. Department of Transportation considers a flight as 'on time' if it arrives at its destination within 15 minutes of the scheduled arrival time and without being diverted or canceled and &lt;a href=&quot;http://airconsumer.ost.dot.gov/rules/Final%20Rule%20on%20Enhancing%20Airline%20Passenger%20Protections.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;can penalize chronically delayed flights&lt;/a&gt; i.e. if they are more than 30 minutes late 50% of the time.&lt;/p&gt;&#xA;&lt;p&gt;There are other issues here- it takes time to buildup data in specific routes and airlines are cautious in the meantime, airports are getting more and more congested making the total flight time to increase etc., but even taking these into account, it is better for airlines to overestimate than underestimate.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-25T23:42:19.730" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23901" PostTypeId="2" ParentId="23797" CreationDate="2015-12-24T13:48:06.427" Score="4" Body="&lt;h2&gt;Yes, usually&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Simulators are pretty accurate, at least for the specific things they're programmed to measure and account for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example we have a pretty good idea how airflow works, so airfoil/wind tunnel simulation is very accurate. We also have quite good ideas of how materials react, flex, break etc, and can model them pretty accurately.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;However&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;No simulation is 100% accurate: there is always potential for things in the &quot;real world&quot; to happen in a way we either didn't account for, or weren't expecting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example sometimes manufacturing flaws mean a material breaks in a way we weren't expecting, or an external influence changes the way something happens. We also don't have a 100% understanding of aerodynamics under all conditions.  This is why we still need real-world testing. There are also circumstances we've never encountered and therefore can't be certain of: eg aircraft are designed to handle around 150% of the force of the strongest known/experienced turbulence, but we can't be truly sure that this hypothetical 150% turbulence would act as &quot;regular&quot; turbulence, merely 50% stronger&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short: yes, the results will be &lt;strong&gt;similar&lt;/strong&gt;, but they will not &lt;em&gt;necessarily&lt;/em&gt; be &lt;strong&gt;identical&lt;/strong&gt;, depending on exactly what you are testing.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-12-24T13:48:06.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23902" PostTypeId="2" ParentId="23887" CreationDate="2015-12-24T13:54:58.130" Score="8" Body="&lt;ol&gt;&#xA;&lt;li&gt;Most airports aren't at 100% capacity any of the time: they simply fit in a few extra flights for a couple of hours until they're back on track, causing relatively little delay.&lt;/li&gt;&#xA;&lt;li&gt;Even those who are at 100% capacity sometimes, aren't usually at 100% capacity 24/7. They can recover by delaying everyone a little for a few hours, with the delay slowly reducing as the airport gets quieter&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;With a very busy airport (Heathrow is often quoted as an example), however, it's possible that the airport is at/near 100% capacity for long periods. Heathrow runs at nearly 100% capacity (roughly 98%), and much of the &quot;quiet&quot; period is actually at the very start of the day which doesn't leave much slack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there's some scope for &quot;absorbing&quot; flight delays: at Heathrow, most aircraft will sit in a &quot;hold&quot; stack for a while before landing. Aircraft join this stack as they arrive and wait their turn to land. If one plane is a little late, another will simply take its place in the queue and everyone jumps &quot;up&quot; one space until the delayed flight. As long as there are aircraft in the stack, short delays or aircraft arriving early don't really make things too chaotic - there are still 60 aircraft landing in the next hour, it doesn't &lt;em&gt;really&lt;/em&gt; matter what order they land in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if there's a bigger problem such as ice, which means the overall capacity is reduced, flights must be cancelled as they simply cannot all fit in. In this case the airport will typically reduce capacity across the board and allow the airlines to choose which flights to cancel. In the case of Heathrow, this will usually be the relatively local, high-frequency routes: eg the once-a-day flight to Sydney, Australia will still fly, but one of the once-per-hour Glasgow flights will be cancelled. For the most part the &lt;em&gt;number&lt;/em&gt; of cancelled flights is down to the airport/ATC, but the &lt;em&gt;specific flights&lt;/em&gt; cancelled are up to the airlines.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2015-12-24T13:54:58.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23903" PostTypeId="2" ParentId="23890" CreationDate="2015-12-24T14:24:32.400" Score="5" Body="&lt;p&gt;Most of high performance propeller aircraft use &lt;a href=&quot;https://aviation.stackexchange.com/questions/1381/how-does-a-constant-speed-propeller-work&quot;&gt;constant speed propellers&lt;/a&gt;, with variable pitch. The speed remains constant over (most of) the flight regime, while the propeller pitch is varied according to the requirement (by the Constant speed unit or CSU).&lt;/p&gt;&#xA;&lt;p&gt;In case the propeller is stopped in flight (for example, due to engine failure), the propeller pitch is increased so that the propeller is basically parallel to the airflow, so as to minimise the drag. This marks the extreme value of feather angle 87&lt;span class=&quot;math-container&quot;&gt;$^{\circ}$&lt;/span&gt; shown in the image.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bQ21x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bQ21x.jpg&quot; alt=&quot;propeller feathering&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from 12charlie.com&lt;/p&gt;&#xA;&lt;p&gt;The propeller range used for forward  flight is usually called the &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; range, where the blade pitch has moderate values with constant speed, which is set by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9333/how-do-throttle-control-and-propeller-control-work-together&quot;&gt;propeller lever&lt;/a&gt;. Obviously, this speed is not constant over the entire range between engine start and shutdown. Usually around the idle, the rpm drops (this varies according to the design) and this gives the constant speed range limit.&lt;/p&gt;&#xA;&lt;p&gt;Now, during landing, the aircraft speed is reduced usually using brakes etc. However, it is possible to do so using propeller itself- basically by turning it backwards. The &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt; range refers to the region where the propeller is producing zero or negative thrust.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://hueyman.overblog.com/propellers-propellers&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;On PT6 powered aircrafts, the Bêta range is controlled by the PCL ( Power Control Lever ) which also directly control blade angle. Yeah, the governor is overriden and by moving the PCL past the idle gate ( you usually have to lift the PCL against that gate ) you directly schedule blade angle in correlation with Ng ( Gaz generator ) speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the beta range, the aircraft can be slowed down by making the propeller pitch flat (0&lt;span class=&quot;math-container&quot;&gt;$^{\circ} 30'$&lt;/span&gt; here) and creating drag. The reverse thrust starts &lt;em&gt;after&lt;/em&gt; this, with the full reverse trust coming in at the limit -15&lt;span class=&quot;math-container&quot;&gt;$^{\circ}$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;I think there is some typo in the figure. From &lt;a href=&quot;http://forum.aerosoft.com/index.php?/topic/74588-beta-range/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this answer&lt;/a&gt;(cleaned up):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Beta range in the Twin Otter is from 11° to -15°(reverse) propeller blade angle.&lt;/p&gt;&#xA;&lt;p&gt;The Beta range lights will be lit when Your in the range from 9°to -15° propeller blade angle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-24T14:24:32.400" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23904" PostTypeId="1" AcceptedAnswerId="23912" CreationDate="2015-12-24T15:46:25.757" Score="19" ViewCount="1591" Body="&lt;p&gt;I was looking at &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6d/Taranis_Test_Flight_10-09-2013.webm&quot; rel=&quot;nofollow noreferrer&quot;&gt;a video&lt;/a&gt; of the &lt;a href=&quot;https://en.wikipedia.org/wiki/BAE_Systems_Taranis&quot; rel=&quot;nofollow noreferrer&quot;&gt;BAE Taranis&lt;/a&gt;, and noticed these weird control surfaces:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j1vDi.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j1vDi.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a matching pair on the underside. They don't seem to move at all throughout the video, even on landing, and yet they seem to be slightly extended. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they?&lt;/p&gt;&#xA;" OwnerUserId="12255" LastEditorUserId="15311" LastEditDate="2017-12-08T11:55:58.030" LastActivityDate="2017-12-08T11:55:58.030" Title="What is the purpose of these odd &quot;control surfaces&quot; on the BAE Taranis?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23905" PostTypeId="1" AcceptedAnswerId="23906" CreationDate="2015-12-24T16:22:22.033" Score="2" ViewCount="270" Body="&lt;p&gt;I am trying to create a mini flying quadrocopter using a Raspberry Pi (mini programmable computer). So far I have hooked up the RPi to 4 motors with controls to each. I'm pretty happy with that side of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The part I need help with is the design of the propeller; my motors are not massive and I want to ensure I get the best design for maximum thrust to weight as well as manoeuvrability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do I need to look for in propeller design considering my limited motors?&lt;/p&gt;&#xA;" OwnerUserId="12774" LastEditorUserId="19" LastEditDate="2015-12-26T16:02:14.553" LastActivityDate="2015-12-26T16:02:14.553" Title="Looking for the correct propeller shape to create a small copter" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2015-12-24T21:44:41.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="23906" PostTypeId="2" ParentId="23905" CreationDate="2015-12-24T16:46:18.310" Score="5" Body="&lt;p&gt;Use Mark Dela's &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xrotor/&quot; rel=&quot;nofollow noreferrer&quot;&gt;XROTOR&lt;/a&gt; - it will give you the chord and twist distribution over span for a given speed, torque and thrust (&lt;a href=&quot;https://aviation.stackexchange.com/questions/7651/is-there-an-equation-which-allow-us-to-perfectly-match-a-helix-propeller-and-an/7657#7657&quot;&gt;well, two out of three&lt;/a&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is based on &lt;a href=&quot;http://www.freeflight.org/DigestOnline/TechLibrary/LarrabeePropDesign.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Larabee's theory&lt;/a&gt; (PFD!) for a minimum induced loss rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a practical solution try to design an optimum propeller for the speed and torque of your motors and then try to find something similar in a  hobby shop. Building the propeller yourself will be a major effort - just balancing them well will not be easy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are into doing everything yourself, try to carve a master and make a mold, maybe from &lt;a href=&quot;http://www.shinetsusilicone-global.com/products/type/two_rtv_mold/index.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;silicone rubber&lt;/a&gt;. Then you can pour as many propellers as you need. Put glass- or carbon fibers into the mold and fill up with thickened epoxy. For thickening use a mixture of &lt;a href=&quot;https://www.freemansupply.com/products/fabrics-fillers-bagging/tooling-plastics-fillers/cotton-flock&quot; rel=&quot;nofollow noreferrer&quot;&gt;cotton short fibers&lt;/a&gt; and &lt;a href=&quot;https://www.freemansupply.com/MSDS/Combined/Fillers/Aerosil200.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerosil 200&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The links to the materials are only for background information - I cannot endorse the sources because I have never ordered from those specific suppliers. The method in general will work, though.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-24T16:53:10.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23907" PostTypeId="1" AcceptedAnswerId="23908" CreationDate="2015-12-24T16:58:26.243" Score="4" ViewCount="6340" Body="&lt;p&gt;Im going to fly to Tucson tommorow. The weather is telling me its going to snow in Denver. So would snow cause a delay or are airliners allowed to take off in this kind of weather?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="946" LastEditDate="2015-12-24T22:08:58.750" LastActivityDate="2015-12-31T04:02:39.823" Title="Would an airliner be allowed to take off in snow?" Tags="&lt;faa-regulations&gt;&lt;airline-operations&gt;&lt;weather&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23908" PostTypeId="2" ParentId="23907" CreationDate="2015-12-24T17:25:19.450" Score="20" Body="&lt;h1&gt;Don't worry about it&lt;/h1&gt;&#xA;&lt;p&gt;While snow can sometimes cause a delay, airports are really good at snow removal.  (Especially airports like Denver that are used to getting a lot of snow.)&lt;/p&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.flydenver.com/sites/default/files/downloads/snowSeasonPrep10-8-2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;flydenver.com&lt;/a&gt; DIA has 500 trained snow removal people and 270 pieces of equipment to clear 12.2 million square feet of runway, taxiways, etc.&lt;/p&gt;&#xA;&lt;p&gt;To put that in perspective, a typical highway (2 lanes each way, with shoulders) is around 38 feet wide each way, or 76 feet for both directions.  If I've done the math correctly, 12.2 million square feet is about 30 miles of road.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dot.state.mn.us/workzone/snowplow-facts.html&quot; rel=&quot;noreferrer&quot;&gt;The state of Minnesota knows a thing or two about plowing snow&lt;/a&gt;.  They use about 1500 drivers and 839 plows to handle 12,000 miles of road.  To plow snow the way the Denver airport does it, they would need 200,000 drivers and 108,000 plows.&lt;/p&gt;&#xA;&lt;p&gt;Here's &lt;a href=&quot;https://youtu.be/sHnIFfSo0xw&quot; rel=&quot;noreferrer&quot;&gt;a YouTube link&lt;/a&gt; that shows off some of Denver's bigger snow removal tools.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Chances are, if you can get to the airport you'll be able to fly (but perhaps not on time)&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-24T17:25:19.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23909" PostTypeId="2" ParentId="23785" CreationDate="2015-12-24T18:11:58.737" Score="4" Body="&lt;p&gt;It seems to come down to the point that as long as &lt;em&gt;someone&lt;/em&gt; is monitoring 121.5 in a specific airspace then not everyone needs to. And it helps avoid multiple ATC facilities responding to the same call. This is from the FAA's &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/FAC/0303.html&quot; rel=&quot;nofollow&quot;&gt;&lt;em&gt;Facility Operation and Administration&lt;/em&gt; orders&lt;/a&gt; (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;3-3-4. EMERGENCY FREQUENCIES 121.5 AND 243.0 MHz&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;d. When facilities are in proximity and no derogation of services will&#xA;  result, &lt;strong&gt;transmit/receive capability should not be provided for each&#xA;  facility&lt;/strong&gt;. The following requirements shall be maintained:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;&lt;p&gt;Geographical area coverage shall not be derogated.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;DF-equipped facilities shall have transmit/receive capability on 121.5 MHz.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;Facilities without emergency frequency capability shall have appropriate landlines for rapid relay of emergency information.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://vfrmap.com/?type=vfrc&amp;amp;lat=37.363&amp;amp;lon=-121.929&amp;amp;zoom=10&quot; rel=&quot;nofollow&quot;&gt;Looking&lt;/a&gt; at &lt;a href=&quot;http://www.airnav.com/airport/KSJC&quot; rel=&quot;nofollow&quot;&gt;KSJC&lt;/a&gt;, there are a lot of other airports close by, so the potential for confusion or conflict on the frequency seems high. My guess is that they leave 121.5 to NorCal TRACON; &lt;a href=&quot;http://www.airnav.com/airport/KPAO&quot; rel=&quot;nofollow&quot;&gt;KPAO&lt;/a&gt; is 10 miles from KSJC and also doesn't have 121.5 available, for example.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-24T18:11:58.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23910" PostTypeId="2" ParentId="23819" CreationDate="2015-12-24T18:54:43.507" Score="2" Body="&lt;p&gt;I don't know if you can check or set the WAAS channel number directly (and I couldn't find anything about it in the C172 G1000 manual) but even if you can there's really no point. When you load the approach, the G1000 gets the WAAS channel number from the database as part of the general approach definition and configures everything automatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I heard or read somewhere that the original concept was that pilots would 'tune' the WAAS channel in the same way that they tune an ILS frequency, but that idea was dropped because an RNAV approach is totally dependent on the database anyway: if you trust the G1000 to load all the waypoints, altitudes and other information correctly from the database then there's no reason to think it will load the wrong WAAS channel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your specific questions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(1) How may I know which approach I am able to shoot?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You read your G1000 manual, check the approach database, and review the approach plates to make sure that the approach is available and you meet all the requirements. If the approach is in the database that doesn't automatically mean that you can fly it, there can also be climb performance or altimeter setting requirements (for example) that are unrelated to the G1000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(2) Is the WAAS channel number automatically selected when I load the corresponding flight plan in G1000?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes. The G1000 sets up the approach completely for you, the only input required (usually!) is to load the approach and select how you initiate it, i.e. via an IAF or radar vectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(3) [Can I] get the LPV glide path guidance without loading any particular approach (set the WAAS CH number for instance?)?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, this wouldn't make any sense. The LPV glideslope is constructed virtually by the G1000 for each approach and the WAAS input just provides &lt;em&gt;correction&lt;/em&gt; to an existing GPS position, it doesn't give you a position directly. So even if you could receive the WAAS corrections directly (and maybe you can, for all I know), the G1000 wouldn't be able to generate a glideslope without all the other approach information about the runway, elevation etc. It would be like asking, &quot;the &lt;a href=&quot;https://en.wikipedia.org/wiki/Magnetic_declination&quot; rel=&quot;nofollow&quot;&gt;magnetic declination&lt;/a&gt; here is 4°W, what's the correct magnetic heading to fly from A to B?&quot; Unless you know the uncorrected heading, the correction by itself isn't useful.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-24T18:54:43.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23911" PostTypeId="1" CreationDate="2015-12-24T19:23:21.187" Score="2" ViewCount="303" Body="&lt;p&gt;I'm looking for an aircraft meeting the following criteria:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Manned (no drones, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Has or had a production run (no prototypes, design-only, etc.)&lt;/li&gt;&#xA;&lt;li&gt;Capable of carrying multiple passengers who are not crew-members (no single-seaters or 2-seaters where both people are required to be part of the crew)&lt;/li&gt;&#xA;&lt;li&gt;Modern avionics, either designed that way or significantly retrofitted if older base model&lt;/li&gt;&#xA;&lt;li&gt;Has the fewest configurable knobs/switches/buttons/etc. in the cockpit that are related to the main flight systems like the engines, APU, electrical system, hydraulic system, control surfaces, brakes, etc. Note that computerized touchscreen displays that expose complex configuration of these systems &lt;strong&gt;should&lt;/strong&gt; be counted against the aircraft's complexity, unless the computer automates the configuration of the system by default. Ignore cosmetic things like knobs to let you change the brightness of the lighting; and don't count the FMS, or &lt;em&gt;displays&lt;/em&gt; or &lt;em&gt;indicators&lt;/em&gt; that give the pilots information about the flight status, either.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Answers don't have to point out &lt;strong&gt;THE&lt;/strong&gt; absolute best craft fitting these criteria currently available; if you have broad experience with systems complexity in a lot of modern aircraft, and you can think of one off the top of your head that is especially clean and simple compared to the rest (either due to automation or just fewer systems to deal with), point it out in an answer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus if you can explain what is automated or taken care of for the pilot without them having to worry about it under normal conditions, but if you're going to explain this, only focus on automation that is unusual or new or unique to the aircraft, not things that are automated on most/all current aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the question stated in another way: To take an aircraft from cold and dark, into the air and land it again in normal, uneventful conditions, which aircraft meeting the criteria above can accomplish this with a minimum of input from the pilot?&lt;/p&gt;&#xA;" OwnerUserId="2432" LastActivityDate="2015-12-24T19:23:21.187" Title="Which modern passenger aircraft has the simplest, most automated systems?" Tags="&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2015-12-24T21:44:29.160" ContentLicense="CC BY-SA 3.0" />
  <row Id="23912" PostTypeId="2" ParentId="23904" CreationDate="2015-12-24T20:10:17.097" Score="23" Body="&lt;p&gt;They look like spoilers but are more precisely called drag rudders. They are not meant to reduce lift like regular spoilers, but increase drag in order to create a yawing moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regular aircraft have a vertical tail for yaw control. Without this, you need some force acting at a lateral distance from the center of gravity for yaw control, and this is what these speed brakes do. They are opened only on one side, and keeping both slightly open increases control power because then one can be closed while the other can be opened further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit&quot; rel=&quot;noreferrer&quot;&gt;Northrop B-2&lt;/a&gt; uses split ailerons to the same effect, and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Horten_Ho_229&quot; rel=&quot;noreferrer&quot;&gt;Horten IX&lt;/a&gt; had a two-stage wooden speedbrake which could be extended near the wingtips. By raising only the smaller brake with small rudder pedal movements, yaw control could be tailored to flight speed. At high speed only small input was needed, and at low speed both brakes could be fully opened for maximum yaw control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LYC2L.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LYC2L.jpg&quot; alt=&quot;Horten IX 3-side view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horten IX V2 3-side view (picture &lt;a href=&quot;http://www.rc-network.de/forum/attachment.php?attachmentid=931173&amp;amp;stc=1&amp;amp;d=1357508678&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the two extended speed brakes near the wingtip in the front view. The real speed brakes were on the lower side of the center wing and right behind the rear landing gear bay (in the drawing called spoilers).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to @RedGrittyBrick for the hint: Yes, the X-47A and &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_X-47B&quot; rel=&quot;noreferrer&quot;&gt;X-47B&lt;/a&gt; also seem to have drag rudders. I guess their large chordwise dimension helps to limit the lift loss when they are extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rVcpw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rVcpw.jpg&quot; alt=&quot;Northrop-Grumman X-47B in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Northrop-Grumman X-47B in flight (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/X-47B_receiving_fuel_from_a_707_tanker_while_operating_in_the_Atlantic_Test_Ranges.jpg/1024px-X-47B_receiving_fuel_from_a_707_tanker_while_operating_in_the_Atlantic_Test_Ranges.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-28T06:04:29.587" LastActivityDate="2015-12-28T06:04:29.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23913" PostTypeId="2" ParentId="23887" CreationDate="2015-12-24T21:25:28.737" Score="2" Body="&lt;p&gt;To add to the other answers, one thing ATC will do is order ground stops. Basically they stop the inbound flights at their origin until there is space to fit them in at the destination. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's an excellent &lt;a href=&quot;https://jethead.wordpress.com/2011/04/23/the-whys-of-airline-ground-stops-for-passengers/&quot; rel=&quot;nofollow&quot;&gt;blog post&lt;/a&gt; on the whys of ground stops and why planes will leave the gate and sit on the ramp sometimes for hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there's congestion or delays at the destination, ATC will often give them a narrow opening to get in the queue. If they can't be in the air in so many minutes then someone else gets the spot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a very informative read. He's also got a &lt;a href=&quot;https://jethead.wordpress.com/2010/02/04/passenger-bill-of-rights-be-careful-what-you-wish-for/&quot; rel=&quot;nofollow&quot;&gt;post&lt;/a&gt; on how the &quot;passenger bill of rights&quot; throws a wrench into this.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2015-12-24T21:25:28.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23914" PostTypeId="2" ParentId="23907" CreationDate="2015-12-24T23:22:52.507" Score="12" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two considerations in snow:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Icing&lt;/li&gt;&#xA;&lt;li&gt;Visibility&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Visibility is easily dealt with and most airlines have approved opspecs to takeoff in low visibility (e.g. down to 300 or 500 feet RVR).  Heavy snow can reduce visibilities to less than a quarter mile (e.g. less than 1200 feet RVR) so there is quite a bit of margin between between typical snowfall and minimum visibility takeoffs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Icing is a bit more of a challenge, but is a well defined problem with specific procedures.  In snow airplanes will be de-iced with Type I fluid and then treated with an application of Type IV fluid for anti-ice protection.  This fluid has a holdover time that you can takeoff within without additional checks.  Some of these holdover times can be low (e.g. 5 minutes for specific conditions) but de-ice is usually where the takeoff bottleneck is and once you are treated you can generally take off without too much further delay.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes will be able to operate in snow, but departure rates will be less than they would be for a normal good weather day.  Departure rates will be limited by runway condition (the airports ability to keep them treated and clean), the throughput of the de-ice facilities and to some degree the aircraft arrival rate (you don't have planes to fly out unless planes are making it in).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Winter ops are normal this time of year (northern hemisphere).  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Continuous heavy snowfall can eventually close an airport if it becomes impossible to keep the runways clean, taxi routes become unusable due to drifting snow or snow transitions into sustained freezing rain (or runs out of de-ice fluid, yes IAH I'm looking at you).  This is a transient problem and the closure would end as soon as conditions ease and the facilities can keep up with it. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-24T23:22:52.507" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23917" PostTypeId="2" ParentId="23899" CreationDate="2015-12-25T12:02:57.567" Score="4" Body="&lt;p&gt;Other than appearing punctual, it will help in preventing connecting flights being missed and to catch up after delays&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2015-12-25T12:02:57.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23918" PostTypeId="2" ParentId="23907" CreationDate="2015-12-25T15:22:10.720" Score="1" Body="&lt;p&gt;Yes, heavy snow delays departures from the Denver airport (based on personal experience). Of course, nothing  horrible: the airport will be cleaned, the plane will be de-iced (twice if your are unlucky enough), and may even catch part of the lost time on the way to destination. Still, it would be unwise to rely heavily on very on-time arrival. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to change into another flight at your destination, and especially if you need to do anything else on time where the airline cannot help (change into unrelated train, or attend important meeting), I would advice to add a few extra hours for the possible delay.&lt;/p&gt;&#xA;" OwnerUserId="917" LastActivityDate="2015-12-25T15:22:10.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23920" PostTypeId="1" CreationDate="2015-12-25T17:39:30.243" Score="6" ViewCount="207" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/23914/3825&quot;&gt;casey's fabulous answer here&lt;/a&gt;, he identifies several ways snow/ice can disrupt airport operations:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Continuous heavy snowfall can eventually close an airport if it&#xA;  becomes impossible to keep the runways clean, taxi routes become&#xA;  unusable due to drifting snow or snow transitions into sustained&#xA;  freezing rain (or runs out of de-ice fluid, yes IAH I'm looking at&#xA;  you). This is a transient problem and the closure would end as soon as&#xA;  conditions ease and the facilities can keep up with it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Are there other ways that heavy snow (or ice) can disrupt airport operations?  Could it perhaps interfere with lighting or navaids?  Are there other airport functions that stop or slow in snow and ice?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-26T06:36:53.680" Title="How else can snowy/icy conditions disrupt airport operations?" Tags="&lt;airport&gt;&lt;icing&gt;&lt;navaids&gt;&lt;cold-weather&gt;&lt;airport-lighting&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23921" PostTypeId="2" ParentId="23768" CreationDate="2015-12-25T18:30:10.280" Score="0" Body="&lt;p&gt;A jet engine is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Brayton_cycle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Brayton cycle&lt;/a&gt; device and has fundamental limits on the performance. From the diagram in the source looks like for the ideal theoretical engine with no friction at all and &lt;a href=&quot;https://en.wikipedia.org/wiki/Overall_pressure_ratio&quot; rel=&quot;nofollow noreferrer&quot;&gt;pressure ratio&lt;/a&gt; about 30 (Boeing 747 engine), the efficiency limit is somewhat 60 %. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that about 40 % of the energy dissipates as the heat, the engine cannot convert it. It is not lost due friction. This is significant percent but less than a half. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;About some WWII jet bomber with pressure ratio about 3 it is possible to say that the major energy loss is because of the engine thermodynamics, not because of the friction.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2020-03-25T15:53:09.163" LastActivityDate="2020-03-25T15:53:09.163" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23922" PostTypeId="2" ParentId="23920" CreationDate="2015-12-25T19:52:20.923" Score="0" Body="&lt;p&gt;There are various ways which heavy snow or ice can disrupt airport operations. Visibility would certainly be an issue, as call tower operators would have trouble visually seeing aircraft and would be unable to accurately judge any distance between aircraft. Additionally, ground crews and pilots would certainly have a tough time trying to navigate around the airport.&lt;/p&gt;&#xA;" OwnerUserId="12779" LastActivityDate="2015-12-25T19:52:20.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23923" PostTypeId="1" CreationDate="2015-12-25T11:28:27.987" Score="0" ViewCount="65" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NmSyP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NmSyP.jpg&quot; alt=&quot;flight CZ3047&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone explain why this happened? Quite odd why he cannot get landing clearance from atc. And is this common? &lt;/p&gt;&#xA;" OwnerUserId="12777" OwnerDisplayName="RailsNewbie" LastActivityDate="2015-12-25T21:23:34.050" Title="Flight with 9 holding patterns before landing on the wrong airport" Tags="&lt;airlines&gt;" AnswerCount="0" CommentCount="3" FavoriteCount="0" ClosedDate="2015-12-26T00:10:36.347" ContentLicense="CC BY-SA 3.0" />
  <row Id="23924" PostTypeId="2" ParentId="23920" CreationDate="2015-12-25T22:22:48.100" Score="0" Body="&lt;p&gt;Well, snow and ice would stick on aircraft, causing a dangerous situation because of unsteady airflow over lift surfaces. It would also decrease visibility, although it would not matter as much in an ILS except for seeing the runway at almost-touchdown altitudes. If the snow or ice is too much, it could interfere with the radar systems of the airport.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2015-12-25T22:22:48.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23925" PostTypeId="2" ParentId="23920" CreationDate="2015-12-26T01:18:36.043" Score="3" Body="&lt;p&gt;There are multiple ways by which snow can affect the operation in an airport.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Snow (and ice) in runway can affect takeoff by absorbing energy and can impact the aircraft after being kicked up by tires.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;During landing, snow or slush in runway can reduce the deceleration rate by reducing friction coefficient, sometimes causing hydroplaning.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The runway length requirements in case of dry and wet conditions are different. This means that some aircraft cannot use the available runway in case of snow/wet conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The requirements to clean the runways (and taxiways) continuously means that the flights will be delayed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The snow may reduce the visibility of runway and terminal visual markers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ramp operations may be affected due to snow/ice.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Beyond a certain level of snow, the airports have to be closed as the aircraft cannot takeoff/land.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, it will be snowing in areas around the airport too. This means that there will be difficulty for people in reaching airport in the first place.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also, see the FAA advisory circulars &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentNumber/150_5200-30C&quot; rel=&quot;nofollow&quot;&gt;AC 150/5200-30C - Airport Winter Safety and Operations&lt;/a&gt; and &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/23145&quot; rel=&quot;nofollow&quot;&gt;AC 91-6A, Water, Slush, and Snow on the Runway&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-26T01:18:36.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23926" PostTypeId="2" ParentId="23920" CreationDate="2015-12-26T06:36:53.680" Score="2" Body="&lt;p&gt;Airport workers often struggle to get to work.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is generally OK for the first 12 hours or so but soon, people need to stop working and rest, especially those with safety critical roles which have legally mandated maximum working and rest periods.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2015-12-26T06:36:53.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23927" PostTypeId="1" AcceptedAnswerId="23935" CreationDate="2015-12-26T07:40:30.677" Score="30" ViewCount="4541" Body="&lt;p&gt;I've seen several times on shows on television, and even talking to older pilots, where they will tell me that old planes were &quot;over-engineered&quot; to add some margin for errors on the designed engineering calculations. Of course, no specifics are given, and so I was thinking in this current age of super-fast computers, better wind tunnels, new software tools, and decades of actual experience, when people design new planes, how much of a margin to they design into them now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like confidence in computer modeling seems to be pretty high, and &quot;over-engineering&quot; seems to have typically meant making things stronger than they &quot;need&quot; to be, more reinforced elements, all things which add to cost and weight of an airplane which are factors that are at odds of profitability and performance.&lt;/p&gt;&#xA;" OwnerUserId="132" LastActivityDate="2015-12-29T00:22:29.523" Title="How &quot;over-engineered&quot; were old planes and how &quot;over-engineered&quot; are they now that we have more advanced testing and research options?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23928" PostTypeId="1" CreationDate="2015-12-26T10:14:37.723" Score="5" ViewCount="143" Body="&lt;p&gt;If I have an Australian CPL can I fly in Indonesia? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How likely am I to obtain employment if I have 250 hrs. flight in Indonesia?&lt;/p&gt;&#xA;" OwnerUserId="12697" LastEditorUserId="11873" LastEditDate="2017-02-14T00:06:52.723" LastActivityDate="2017-02-14T00:06:52.723" Title="I have an Australian CPL, what do I need to fly in Indonesia?" Tags="&lt;international&gt;&lt;career&gt;&lt;australia&gt;" AnswerCount="0" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23929" PostTypeId="1" CreationDate="2015-12-26T11:21:14.190" Score="16" ViewCount="6522" Body="&lt;p&gt;This question is motivated by another SE Aviation answer where @Peter Kampf writes the following two useful bits of information:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft like to fly near their optimum L/D ratio, where drag reaches&#xA;  its minimum.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Observation aircraft which want to optimize flying time will fly&#xA;  slower that what optimum L/D requires, especially if they use&#xA;  propellers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/23768/do-aircraft-use-the-majority-of-their-fuel-to-overcome-friction&quot;&gt;Do aircraft use the majority of their fuel to overcome friction?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm trying to understand this more: Why would maximum fly-time not coincide with max L/D operating point? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this something to do with the jet engine fuel consumption characteristic? i.e. Does the minimum fuel-consumed-per-unit-time point not coincide with the optimum L/D point? But if your payload is fixed, so is your lift &amp;amp; hence your velocity choice that gives you that lift right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. For a given payload, lift is fixed. For a given lift, minimum drag leads to max fuel economy? And max economy means max dwell time? What gives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O08Oz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O08Oz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity I assume we can ignore the climb / descent / acceleration etc. for now. And only consider the level flight segment at fixed speed. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="14897" LastEditDate="2018-06-27T20:27:36.330" LastActivityDate="2020-04-04T02:33:32.253" Title="Why would maximum fly-time (endurance) not coincide with max L/D operating point?" Tags="&lt;aircraft-performance&gt;&lt;drag&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="23930" PostTypeId="2" ParentId="23929" CreationDate="2015-12-26T12:07:09.223" Score="21" Body="&lt;p&gt;Maximum dwell time or maximum endurance occurs when the power required is minimum. Hence, in this case, the maximum endurance speed is one where the power required is minimum, while in case of maximum range speed, the thrust required is minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For maximum endurance, we must minimize the fuel consumed per unit time i.e. the fuel flow. For maximum range, we must minimize the fuel used per unit distance traveled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of propeller aircraft, the fuel flow rate is proportional to the power produced. Hence, the maximum endurance occurs at a point where the power is minimum. For (turbo)jets, the minimum fuel flow occurs when the thrust is minimum. Hence the maximum endurance occurs when the L/D is maximum. For turbofans, it is somewhere in-between.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Consider a propeller aircraft in a steady, level flight. For determining the condition where the energy expenditure is minimum, we have,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P = W (\frac{C_{D}}{C_{L}})V$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;is minimum. For steady flight, we have,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$V = \sqrt{\frac{W}{\frac{1}{2} \rho S C_{L}}}$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This gives,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P = \sqrt{\frac{W}{\frac{1}{2} \rho S}}(\frac{C_{D}}{C_{L}^{\frac{3}{2}}})$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, for propeller aircraft, the minimum power and maximum endurance occurs when $\frac{C_{L}^{\frac{3}{2}}}{C_{D}}$, rather than $\frac{C_{L}}{C_{D}}$ is maximum. Due to this, the minimum power (maximum endurance) condition occurs at a speed which is 76% of the minimum drag (maximum range) condition. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tVxsV.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tVxsV.gif&quot; alt=&quot;Range- Endurance&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from eaa1000.av.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node99.html&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.eaa1000.av.org/technicl/perfspds/perfspds.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Thrust is a force that moves the aircraft. In steady, level flight, this is equal to the drag (if it is more/less, the aircraft will accelerate/decelerate). Power is the rate of doing work i.e. the energy consumed per unit time or rate of energy expenditure (by the a/c powerplant). This is why we are considering minimum power i.e. rate of energy expenditure for determining endurance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power is the product of force (thrust) and velocity. Think of it in this way- as speed increases, the drag decreases, reaches a minimum and then increases. However, as the power is product of drag (i.e. thrust) and velocity, it too follows the a similar path; however, the minimum is reached &lt;em&gt;before&lt;/em&gt; the minimum drag. That speed gives the maximum endurance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For jet engined aircraft, the speeds are different. In this case, the speed corresponding to minimum $\frac{C_{L}}{C_{D}}$ gives maximum endurance, while the speed corresponding to $\frac{C_{L}^{\frac{1}{2}}}{C_{D}}$ gives maximum range. Also, see &lt;a href=&quot;http://nptel.ac.in/courses/101106041/Chapter%207%20-%20Lecture%2025%2021-12-2011.pdf&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2015-12-26T15:40:10.190" LastActivityDate="2015-12-26T15:40:10.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23931" PostTypeId="2" ParentId="23927" CreationDate="2015-12-26T13:56:01.907" Score="2" Body="&lt;p&gt;I think calculating stresses and loads are no better now than 50 years ago. Engineers understood forces and physics no differently then than now. They just used a &lt;a href=&quot;https://en.wikipedia.org/wiki/Slide_rule&quot; rel=&quot;nofollow&quot;&gt;slide rule&lt;/a&gt; instead of software, but they got the same results. Instead of modeling things, they build real life ones and tested them. They got the same answers. They built a wing, bent it till it broke and discovered its strength and were able to build one to any load specification needed without overbuilding it. Modern software just gets results cheaper and faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The big differences between then and now are materials and system evolution. Not calculating forces and stresses.&lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="849" LastEditDate="2015-12-28T04:24:55.367" LastActivityDate="2015-12-28T04:24:55.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23932" PostTypeId="2" ParentId="23927" CreationDate="2015-12-26T14:11:37.360" Score="15" Body="&lt;p&gt;The legal &amp;quot;over engineering&amp;quot; factor has not been changed since 1970:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ebe296b092b011795824c49dacadaf1b&amp;amp;mc=true&amp;amp;node=se14.1.25_1303&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;FAR Part 25, section 303:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Unless otherwise specified, a factor of safety of 1.5 must be applied&#xA;to the prescribed limit load which are considered external loads on&#xA;the structure. When a loading condition is prescribed in terms of&#xA;ultimate loads, a factor of safety need not be applied unless&#xA;otherwise specified.&lt;/p&gt;&#xA;&lt;p&gt;&lt;sub&gt;[Amdt. 25-23, 35 FR 5672, &lt;strong&gt;Apr. 8, 1970&lt;/strong&gt;]&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-26T14:11:37.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23933" PostTypeId="2" ParentId="23927" CreationDate="2015-12-26T14:20:06.563" Score="12" Body="&lt;p&gt;Over-engineering is a concept in value engineering, not aircraft design. In general, over-engineering means making the design more robust or unnecessarily complicated than necessary. In that sense, I would say that aircrafts are/were rarely over-engineered. Older aircraft were &lt;em&gt;more conservative&lt;/em&gt; in determining the loads. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In structural design of any aircraft, the designer tries to make the aircraft safe in a number of steps:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Safety factor (which for transport aircraft, is 1.5)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Conservative material properties&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Conservative loads.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The process followed now is pretty much the same; however, the engineers are able to determine the loads acting on the structures to a greater precision compared to the earlier times and are able to optimize the structure accordingly. The safety factor and taking of conservative material properties have not changed much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Though one can say that, for example, making the wing spar thicker than necessary to account for unforeseen loads is good from structural point of view, it is bad from performance/weight/fuel consumption views. The problem is that if the designer knowingly pads the safety factor more than necessary, he's actually reducing the aircraft performance. As a result, over engineering (more than design or regulatory requirements) is plain &lt;em&gt;bad design&lt;/em&gt; and is not recommended. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, the process haven't changed over time- it is simply that the tools have improved and more data is available for use.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are other issues here- aircraft like F-35 Lightning II are repeatedly called over-engineered, but the point is that they were designed for the given specifications. For example, F-35 was required by design to perform the tasks of a number of aircraft and as such is having a significantly difficult engineering period.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-26T14:20:06.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23934" PostTypeId="1" AcceptedAnswerId="23940" CreationDate="2015-12-26T14:26:06.727" Score="27" ViewCount="3290" Body="&lt;p&gt;In many cases, the maximum landing weight of an aircraft is lower than the takeoff weight due to the amount of fuel it carries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While some aircraft have fuel dumping systems, others like the A320 family and Boeing 737 do not, and so have to cycle nearby until they have burned enough fuel. (And in case they have to land immediately, they will simply to, but need further inspection due to the high stress on brakes and landing gears)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: If an aircraft has to cycle to burn fuel, are there measures to burn fuel faster? Lower altitude requires more thrust and so needs more fuel, but are there more ways? Like a slight air brake setting?&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="19" LastEditDate="2016-11-23T13:07:13.640" LastActivityDate="2018-12-30T19:55:48.413" Title="What are the ways to burn fuel faster in case of emergency without fuel dumping system?" Tags="&lt;emergency&gt;&lt;fuel-dumping&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23935" PostTypeId="2" ParentId="23927" CreationDate="2015-12-26T14:44:44.057" Score="33" Body="&lt;p&gt;You are right that older designs used (and needed!) higher safety margins. I would, however, not call this over engineering. But that is besides the point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest advances have been made in materials! Not just new alloys, but much better quality control in manufacturing. The aluminium sheets and slabs you would get from a factory 50 or 80 years ago had much greater variations in local strength, and in strength between different production batches. The same goes for fasteners, forgings, whatever. Computer-controlled manufacturing and the relentless effort to improve quality and consistency have made this possible. Only wood is still the same as it was then, but Basil Bourque is right: Processing the wood has also improved by leaps and bounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But now consider what we do when we stress a wing: We use the maximum static lift coefficient, add aileron deflection and use that bending moment at v$_A$ to size our wing spar. We do this by applying a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c6eb9116ff329599d2bc32097096e39d&amp;amp;mc=true&amp;amp;node=se14.1.25_1303&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;safety factor of 1.5&lt;/a&gt; (§25.303). For parts with a more error-prone production process additional factors need to be added (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=c6eb9116ff329599d2bc32097096e39d&amp;amp;mc=true&amp;amp;n=pt14.1.25&amp;amp;r=PART&amp;amp;ty=HTML#se14.1.25_1619&quot; rel=&quot;nofollow noreferrer&quot;&gt;see §25.619&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now consider what happens in the real world: The dynamic maximum lift coefficient, which does not obey the rules and regulations imposed by the FAA, will easily be 1.3 times bigger than the static lift coefficient used for stressing the wing spar. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620#3620&quot;&gt;In tests up to 150% have been achieved&lt;/a&gt;. Makes you think how sensible that safety factor really is. While we understand the static loads very well (because they are easy to study), &lt;a href=&quot;http://www.nytimes.com/1984/07/28/us/f-18-builder-says-test-missed-design-flaws.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;dynamic and fatigue loads still happen to surprise the engineers from time to time&lt;/a&gt;. A little extra margin sometimes can be quite useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurofighter&lt;/a&gt; the structural safety factor was indeed reduced to 1.4 with the reasoning that more precise modeling and simulation would allow to use a smaller margin.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2015-12-29T00:22:29.523" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="23939" PostTypeId="2" ParentId="23934" CreationDate="2015-12-26T16:26:45.287" Score="3" Body="&lt;p&gt;For increasing fuel burn, the pilot can simply increase drag by increasing the speed. This results in requirement of more thrust, which requires more fuel. He can do it in lower altitudes, but the holding altitude has to be cleared by ATC, I guess.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that even jettisoning of fuel takes quite some time.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-26T16:26:45.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23940" PostTypeId="2" ParentId="23934" CreationDate="2015-12-26T17:02:23.333" Score="31" Body="&lt;p&gt;This question (sorry to say) is sort of moot because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;if you have an urgency to land (e.g. cargo fire), you don't care if you are overweight and you'd land anyway&lt;/li&gt;&#xA;&lt;li&gt;if you have time to dump fuel, the situation isn't as desperate, and you can easily wait just a bit longer.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The large jets (e.g. Airbus A380, Boeing 777) have a fuel dumping system because, with full fuel, these planes can travel &lt;em&gt;up to 12 hours or more&lt;/em&gt;! That is to say, if you don't dump fuel, you might have to fly around all day to get down to your normal landing weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus A320 and Boeing 737 are different: they usually fly 1~3 hours route, and may stretch to 6 hours on a full tank. So, to begin with, you need less time to burn fuel. Plus, these (relatively) small planes can land on shorter runways, which means your airport choice will not be as restricted as with a large jet.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, as to &lt;em&gt;actually&lt;/em&gt; answering your question......&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps and gears have speed restrictions. You cannot fly full throttle with these deployed. That being said, if the pilots put the airplane in landing configuration (full flaps + gear down), drag will increase significantly and they will need more thrust to maintain altitude and airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can technically achieve that with spoilers, but it's dangerous. Spoilers destroy lift, so what you're really doing is reducing the effectiveness of your wings and compensate that by flying faster and/or increasing your angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then again, if you're desperate, just land right away......&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2015-12-27T13:50:48.577" LastActivityDate="2015-12-27T13:50:48.577" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23941" PostTypeId="2" ParentId="23934" CreationDate="2015-12-26T17:08:03.877" Score="23" Body="&lt;p&gt;Fuel flow is proportional to air density, so it is advisable to stay low. Since the propulsive power requirement scales with the cube of airspeed, flying faster is also advised. However, when flying below 10.000 ft all civilian traffic has to obey a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1294/what-is-the-speed-limit-in-european-airspace&quot;&gt;speed limit of 250 KIAS&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My recommendation is to&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;stay low and fly in approach configuration (gear, flaps and slats out) as close to 250 KIAS as the configuration allows. A &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20000712-0&quot; rel=&quot;noreferrer&quot;&gt;Hapag-Lloyd A310&lt;/a&gt; demonstrated in 2000 how much an extended gear will increase fuel consumption.&lt;/li&gt;&#xA;&lt;li&gt;climb to an altitude just above FL100 and fly as fast as possible. Depending on the aircraft, spoilers or speed brakes might still be used to increase drag, but the gear and high lift devices have to stay in.&lt;/li&gt;&#xA;&lt;li&gt;fly a sawtooth pattern: Climb and descent in rapid succession, and use all drag-increasing means during descent, including sideslip.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Which version is best depends on the particular airframe. My personal favorite is number three: Few maneuvers beat a proper sideslip for sheer fun.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-12-27T07:46:25.250" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23942" PostTypeId="1" AcceptedAnswerId="23949" CreationDate="2015-12-26T18:20:13.343" Score="16" ViewCount="10115" Body="&lt;p&gt;I can't find the reason why rockets are able to produce so much thrust when compared to turbojets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do know that the rockets carry their own own supply of oxygen since there is no oxygen in space or the upper region of our atmosphere. And that the upper stages use hydrogen for longer range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But given that RP-1 is kerosene basically. A highly refined form of kerosene that is used in jets but kerosene nevertheless. Is there something else that gives the first stage of the rocket it's unbelievable thrust or is it just all down to the RP-1 fuel?&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastEditorUserId="15311" LastEditDate="2018-05-27T13:34:01.687" LastActivityDate="2019-10-27T06:37:07.350" Title="How do rocket engines produce more thrust than aircraft jet engines?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;thrust&gt;&lt;rocket&gt;" AnswerCount="7" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23944" PostTypeId="2" ParentId="23929" CreationDate="2015-12-26T20:09:03.037" Score="7" Body="&lt;p&gt;The polar point for maximum flight time only coincides with the minimum drag point when engine thrust does not change over speed. This is approximately true for pure turbojets and rockets. If thrust creation involves accelerating a big mass flow of air, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1086/why-are-propeller-engines-uncommon-on-commercial-aircraft/10037#10037&quot;&gt;declining thrust with increasing speed for a given engine power&lt;/a&gt; shifts the optimum to lower speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a more general optimization goal we need to minimize not drag, but fuel flow. Since thrust varies with fuel flow for propeller and bypass engines (as it does for &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717?s=1%7C0.2335#14717&quot;&gt;ramjets&lt;/a&gt;), this can be calculated when we model thrust $T$ over speed $v$ as $T \varpropto v^{n_v}$ with $n_v$ a negative number for propeller and turbofan engines, and positive for ramjets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting from the equilibrium in steady flight&#xA;$$T_0\cdot v^{n_v} = c_D\cdot\frac{\rho}{2}\cdot v^2\cdot S$$&#xA;we can express the speed $v$ in terms of the lift coefficient $c_L$&#xA;$$T_0 = c_D\cdot\left(\frac{\rho}{2}\cdot S\right)^{\frac{n_v}{2}}\cdot\left(\frac{m\cdot g}{c_L}\right)^{1-\frac{n_v}{2}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T_0$ is the reference thrust at a specific speed and depends only on fuel flow. You can see it equally as the thrust setting, and we want to minimize this. Therefore, we approximate the drag coefficient with the quadratic polar ($c_D = c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$), differentiate the right part of the equation with respect to $c_L$ and look for the lift coefficient at which it is zero:&#xA;$$0 = \frac{n_v-2}{2}\cdot c_{D0}\cdot c_L^{\frac{n_v-4}{2}} + \frac{n_v+2}{2\cdot\pi\cdot AR\cdot\epsilon}\cdot c_L^{\frac{n_v}{2}}$$&#xA;$$\Leftrightarrow c_L = \sqrt{\frac{2-n_v}{n_v+2}\cdot\pi\cdot AR\cdot\epsilon\cdot c_{D0}}$$&#xA;This by itself is not yet helpful, but if we look at the ratio of the drag components at specific values of $n_v$, the answer becomes clear:&#xA;$$c_{Di} = \frac{c_L^2}{\pi\cdot AR\cdot\epsilon} = \frac{2-n_v}{n_v+2}\cdot c_{D0}$$&#xA;Propeller aircraft ($n_v$ = -1): $c_{Di} = 3\cdot c_{D0} \Rightarrow$ 76% of the speed for lowest drag&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbofan aircraft ($n_v$ = -0.5): $c_{Di} = \frac{5}{3}\cdot c_{D0} \Rightarrow$ 88% of the speed for lowest drag&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbojet aircraft ($n_v$ = 0): $c_{Di} = c_{D0} \Rightarrow$ 100% of the speed for lowest drag&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For optimum loiter speed, the induced drag of a propeller aircraft needs to be three times as big as the zero-lift drag. As &lt;a href=&quot;https://aviation.stackexchange.com/questions/16437/why-do-airplanes-have-to-retract-landing-gear/16446#16446&quot;&gt;induced drag drops with increasing speed&lt;/a&gt;, only for turbojets will the optimum polar point for maximum flight duration be equal to that at the lowest drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient&lt;br&gt;&#xA;    $n_v \:\:\:$  thrust exponent, as in $T = T_0\cdot v^{n_v} $&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient&lt;br&gt;&#xA;    $c_{Di} \:\:$  induced drag coefficient&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2015-12-27T08:56:57.240" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23946" PostTypeId="1" CreationDate="2015-12-26T21:54:52.653" Score="9" ViewCount="1115" Body="&lt;p&gt;The ARCA board is being hawked as achieving 430 pounds of lift from 36 electric fan motors for six minutes of 'flight.'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/7TnqBM_KUyE?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c.f. : &lt;a href=&quot;http://www.theverge.com/2015/12/24/10663228/arcaspace-arcaboard-hoverboard-skateboard&quot;&gt;http://www.theverge.com/2015/12/24/10663228/arcaspace-arcaboard-hoverboard-skateboard&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my uneducated eye, getting 12 pounds of static thrust from each of the small fan motors (430 pounds / 36 motors) seems unreasonable and perhaps impossible. The engineer says that it has 272 horsepower, so that would be 7.56 horsepower or 5.6kW per motor, which seems on the high side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the a) theoretical and b) realistic amounts of thrust that one can assume from what looks like a 10-15cm diameter fan?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2015-12-27T06:29:49.613" LastActivityDate="2016-02-16T14:49:46.153" Title="Does the ARCA hoverboard violate known limits on small-diameter electric fans?" Tags="&lt;hover&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23947" PostTypeId="1" AcceptedAnswerId="27241" CreationDate="2015-12-26T21:58:09.477" Score="14" ViewCount="410" Body="&lt;p&gt;While reading &lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/GB/2004-09-01-UK.pdf&quot; rel=&quot;nofollow&quot;&gt;this report&lt;/a&gt; detailing a tire failure and actions taken, I noticed a peculiarity: The flight took off and landed at Glasgow without continuing to Malta (its intended destination) yet the &lt;em&gt;Actions taken&lt;/em&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For flights from Malta, takeoffs to be carried out with flaps 5 only. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How would the operator find an issue with flights out of Malta for a flight intended to &lt;em&gt;land&lt;/em&gt; in Malta, that never did (by virtue of returning to Glasgow)? Is it policy or practice to check all aspects of the flight including those that were not reached due to the incident? Was something not mentioned likely to have been found at Malta (perhaps damage from a previous takeoff)?&lt;/p&gt;&#xA;" OwnerUserId="743" LastEditorUserId="100" LastEditDate="2020-05-12T14:07:19.937" LastActivityDate="2020-05-12T14:07:19.937" Title="How did this incident report detailing a flight taking off and landing at Glasgow result in safety changes at a distant airport?" Tags="&lt;accident-investigation&gt;&lt;incidents&gt;&lt;aaib&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23948" PostTypeId="1" AcceptedAnswerId="23953" CreationDate="2015-12-26T22:22:30.200" Score="12" ViewCount="560" Body="&lt;p&gt;My safety pilot is endorsed for complex, and will be PIC for the entire flight. I would also log PIC for the time I spend under the hood.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will eventually get my complex endorsement, but insurance is much cheaper if I have time in type, so in the long run it will be cheaper for me to build time in type and work towards my instrument rating at the same time.&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2015-12-28T18:32:59.443" Title="Can I log simulated instrument time in a complex plane without having a complex endorsement?" Tags="&lt;faa-regulations&gt;&lt;logging&gt;&lt;pic&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23949" PostTypeId="2" ParentId="23942" CreationDate="2015-12-26T22:25:05.060" Score="19" Body="&lt;p&gt;For one, don't only look at the engine, but at the whole propulsion system. This includes tanks, piping, controls, pumps and the actual engine. Now the rocket looks much less favorable, especially if you size the tanks for equal running times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rocket does not need any of the parts which are ahead of the combustion chamber of a jet and also does not need the turbine. Also, being designed for full thrust only, it does not need an adjustable nozzle. Please look below at the engine installation of a typical airliner (I tried but could not find a fitting cross section of a turbojet plus intake):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F4Jsb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F4Jsb.jpg&quot; alt=&quot;Jet engine and nacelle cutaway drawing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engine and nacelle cutaway drawing (picture &lt;a href=&quot;http://barriosengineeringportfolio.weebly.com/uploads/1/6/6/5/16650342/3393920_orig.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). As @Talisker correctly observed in the comments, the labels &quot;high speed jet&quot; and &quot;low speed jet&quot; have to be swapped in order to be correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only the part labeled &quot;combustor&quot; and the section aft of the turbine are actually comparable to a rocket engine - all else is needed to condition and compress air or drive the turbo machinery in front. A rocket enjoys the luxury of being fed propellant and oxidizer at just the right ratio, condition and at high pressure, and since the oxidizer is mostly pure liquid oxygen, the turbo pumps for compressing it can be much smaller than the turbo machinery of a jet which works with an 80% nitrogen - 20% oxygen mixture of gasses.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-05-27T04:59:02.197" LastActivityDate="2018-05-27T04:59:02.197" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="23950" PostTypeId="2" ParentId="23946" CreationDate="2015-12-26T23:11:29.217" Score="10" Body="&lt;p&gt;The key is that the Arca board only works in ground effect. Therefore, the pressure difference over the area of the board is the key for calculating its power needs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strike&gt;From the video I would estimate the size to be 0.6 x 1.2 m&lt;/strike&gt; thanks to @mins more thorough research we know that the board measures 1.45 x 0.76 m for an area of 1.1 m². To lift both the occupant and the board itself it claims to create 430 pounds of force, equivalent to 195 kg of mass in Earth's gravity, so the pressure increase between top and bottom is 1740 N/m² or just 1.7% of atmospheric pressure. This is not much when you consider that a turbofan compressor stage can create a pressure differential of 1.7, albeit at &lt;a href=&quot;https://aviation.stackexchange.com/questions/22316/why-do-turbofan-blade-tips-exceed-the-speed-of-sound-while-prop-tips-should-not/22317?s=1%7C0.2055#22317&quot;&gt;much higher speeds&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept is basically the same as the &lt;a href=&quot;http://hiller.org/flying-platform.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hiller flying platforms&lt;/a&gt; of the 1950s, the first of which was powered by two 44 HP engines. Since the intake geometry of the Arca board is - how should I say - less than optimum, it can not fly as high as the Hiller vehicles &lt;strike&gt;and I find the claimed 272 HP hard to believe&lt;/strike&gt; and the high power draw is due to the low efficiency of 36 closely coupled blowers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/maSZM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/maSZM.jpg&quot; alt=&quot;Hiller VZ-1 Pawnee&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hiller VZ-1 Pawnee (picture &lt;a href=&quot;http://Hiller_VZ-1_Pawnee_(2).jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To calculate the exact amount of power needed I would need to calculate the mass flow from below the board at the given pressure, which depends nonlinearly on altitude. Then I would need to calculate the power to produce this mass flow at the known pressure differential with 36 small blowers. Sorry, but even my Hoerner books do not cover this. What is certain is that the thrust from the 36 blowers is not nearly sufficient to lift the 195 kg when out of ground effect. The board only works at very little altitude when the outflow cross section around the board is restricted. This gives it an automatic altitude limit of a few centimeters and makes it self-stabilizing in pitch and yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It takes some thick skin to watch the full length of this platitude-filled piece of marketing for an obvious gimmick. The camera angles were chosen to make it look fly higher than it actually can, and in the one shot where it does fly higher you cannot see who or what is standing on top. Anybody spending 20 grand on this is going to regret it quite soon.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the answer provided by Bruce Abbott to @mins' &lt;a href=&quot;https://electronics.stackexchange.com/questions/208027/how-plausible-is-the-claim-about-a-hovering-board-battery-solution&quot;&gt;question on Electrical Engineering SE&lt;/a&gt; the question can be solved. Bruce approaches the problem from the electrical side and links to a 120&amp;nbsp;mm blower which creates 74 N thrust and consumes 7 kW of power. He calculates 65 kg for the batteries and 36 kg for the blowers, for an estimated mass of the board of 110 kg. However, in combination the thrust from closely coupled blowers will certainly be lower than that of an isolated blower with ideal flow conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion:&lt;/strong&gt; Looks possible, no limits are busted, but there is some potential for further optimization and badly needed mass savings on the board.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2015-12-27T10:22:21.210" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23952" PostTypeId="2" ParentId="23948" CreationDate="2015-12-27T01:14:07.050" Score="1" Body="&lt;p&gt;&lt;strong&gt;Yes.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can log actual and simulated instrument time while being the sole manipulator of the controls without the complex endorsement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See FAR 61.51.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2015-12-27T01:14:07.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23953" PostTypeId="2" ParentId="23948" CreationDate="2015-12-27T01:46:07.303" Score="11" Body="&lt;p&gt;Yes. You can, as long as you have the appropriate rating and are the sole manipulator of controls. From a &lt;a href=&quot;http://www.soaringsafety.org/briefings/FAQ_Glider.PDF&quot; rel=&quot;nofollow&quot;&gt;FAA response to a similar question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... a private pilot may log pilot-in-command time, in a complex or high performance airplane, for those portions of the flight when he or she is&#xA;  the sole manipulator of the controls because the aircraft being operated is single-engine land and the private pilot holds a single-engine land rating.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... 14 CFR section 61.31 requires a person to have an endorsement from an authorized instructor before he or she may act as pilot in command of certain aircraft (a complex airplane, a high performance airplane, a pressurized airplane capable of operating at high altitudes, or a tailwheel airplane). &lt;strong&gt;These endorsements are not required to log pilot-in-command time under 14 CFR&#xA;  section 61.51(e)&lt;/strong&gt;. (emphasis mine)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Excerpt from &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.51&quot; rel=&quot;nofollow&quot;&gt;§61.51 Pilot logbooks&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) Logging pilot-in-command flight time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A sport, recreational, private, commercial, or airline transport pilot may log pilot in command flight time for flights- &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(iv) When the pilot performs the duties of pilot in command while under the supervision of a qualified pilot in command provided—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(A) The pilot performing the duties of pilot in command holds a commercial or airline transport pilot certificate and aircraft rating that is appropriate to the category and class of aircraft being flown, if a class rating is appropriate&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="62" LastEditDate="2015-12-28T18:32:59.443" LastActivityDate="2015-12-28T18:32:59.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23954" PostTypeId="2" ParentId="23927" CreationDate="2015-12-27T07:56:00.200" Score="3" Body="&lt;p&gt;On a different note from the other answers, there's been a few articles indicating that newer 'bone' like designs are being considered and implemented by companies like Airbus.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airbus has partnered with Autodesk to rethink the design of those&#xA;  lowly partitions. Its new partition debuted today at the Autodesk&#xA;  University conference in Las Vegas and, thanks to 3-D printing and&#xA;  some wild new algorithms based on slime mold and bone growth, it&#xA;  weighs in at just 66 pounds. Airbus’s current partitions weigh 143&#xA;  pounds apiece. “Our goal was to reduce the weight by 30 percent, and&#xA;  we altogether achieved &lt;strong&gt;weight reduction by 55 percent&lt;/strong&gt;,” says Bastian&#xA;  Schaefer, innovation manager at Airbus. “And we’re right at the&#xA;  beginning.”&#xA;  &lt;a href=&quot;http://www.wired.com/2015/12/airbuss-newest-design-is-based-on-slime-mold-and-bones/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.wired.com/2015/12/airbuss-newest-design-is-based-on-slime-mold-and-bones/&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are even some pretty impressive futuristic designs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GZ93I.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GZ93I.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airbus.com/innovation/future-by-airbus/the-concept-plane/&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airbus.com/innovation/future-by-airbus/the-concept-plane/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smithsonianmag.com/arts-culture/aircraft-design-inspired-by-nature-and-enabled-by-tech-25222971/?no-ist&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.smithsonianmag.com/arts-culture/aircraft-design-inspired-by-nature-and-enabled-by-tech-25222971/?no-ist&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1622" LastEditorUserId="1622" LastEditDate="2015-12-28T23:20:52.080" LastActivityDate="2015-12-28T23:20:52.080" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23955" PostTypeId="1" AcceptedAnswerId="23985" CreationDate="2015-12-27T11:38:34.697" Score="16" ViewCount="2653" Body="&lt;p&gt;In a modern commercial airliner how much percentage of its engine power is used to power its own compressor, the ducted fan and other ancillaries like the airconditioning etc? Maybe it can't be calculated with accuracy but I'm looking for at least an approximate figure.&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastEditorDisplayName="user12782" LastEditDate="2015-12-28T14:31:42.363" LastActivityDate="2018-01-15T19:57:48.153" Title="How much power is drawn by a turbofan to power its own compressor?" Tags="&lt;engine&gt;&lt;turbofan&gt;&lt;compressor&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23956" PostTypeId="1" AcceptedAnswerId="23958" CreationDate="2015-12-27T06:08:57.370" Score="12" ViewCount="726" Body="&lt;p&gt;A company called Windspeed Technologies posted the following &lt;a href=&quot;https://www.youtube.com/watch?v=cLZg-gfLgcI&quot; rel=&quot;nofollow noreferrer&quot;&gt;concept video&lt;/a&gt; of a panorama seating option aboard a commercial plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the limited understanding I have of the phenomena called &lt;a href=&quot;https://en.wikipedia.org/wiki/Flow_separation&quot; rel=&quot;nofollow noreferrer&quot;&gt;flow separation&lt;/a&gt;, such a structure on the fuselage may induce separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/daZVr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/daZVr.png&quot; alt=&quot;Separation around a sphere&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sphere example here is just an approximate representation for the semi-ellipsoid. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I am asking this question, is because the ellipsoid is relatively near the tail section of the plane. It does not seem like a good idea to have a turbulence inducing structure that close to the tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How will this addition to the plane fuselage effect the air flow ? Worst case, can it cause navigation problems due to turbulence near the tail section ?&lt;/p&gt;&#xA;" OwnerUserId="12792" OwnerDisplayName="imranal" LastEditorUserId="19" LastEditDate="2016-07-06T16:02:15.687" LastActivityDate="2016-07-06T18:03:15.717" Title="What is the aerodynamic effect of a panorama (skydeck) near the tail section of a commercial airline?" Tags="&lt;aerodynamics&gt;&lt;turbulence&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23957" PostTypeId="2" ParentId="23956" CreationDate="2015-12-27T12:52:07.497" Score="0" Body="&lt;p&gt;So, the &quot;cupola&quot; on top of the airplane is more of a teardrop shape than spheroid or ellipsoid. Many of the control surfaces on aircraft use this shape, so the induced/pressure drag caused by it would not be much and since it is smaller than those surfaces, it would have less of that drag. The addition of that surface adds more surfaces area, which creates more, though somewhat negligent, parasite drag. Overall, the airworthiness of the airplane would not be affected much, although a Supplemental Type Certificate (STC) would be needed to add the structure on.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2015-12-27T14:10:14.627" LastActivityDate="2015-12-27T14:10:14.627" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23958" PostTypeId="2" ParentId="23956" CreationDate="2015-12-27T13:07:10.287" Score="13" Body="&lt;p&gt;You're correct that the structure may induce separation under some conditions. However, the effects are unlikely to be significant given the (publicly) available data on the concept. From the available images, the deck is quite small, with a seating capacity of only two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/en3Mh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/en3Mh.jpg&quot; alt=&quot;Skydeck&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from gizmag.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it is located at some distance in front of the vertical fin and appears shaped to reduce drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EZCsA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EZCsA.jpg&quot; alt=&quot;Skydeck&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from technology.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The company says that &lt;a href=&quot;http://www.businesstraveller.com/news/new-window-seat-design-patent-unveiled&quot; rel=&quot;nofollow noreferrer&quot;&gt;it has over come many design hurdles&lt;/a&gt; including&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... structural modification, structural integrity of the canopy to withstand a bird strike and flight loads, condensation, noise levels, UV protection, aerodynamic drag, potential disruption to the vertical tail's performance, safety, ingress and egress requirements per the FAA requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though this should be taken with a grain of salt (it from the company after all), there is nothing insurmountable in the engineering sense. For example, the canopies of fighter jets are of similar size in smaller aircraft and they are operated without problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AWACS aircraft routinely carry huge antenna on top of their fuselages; they have no problem flying, albeit with reduced performance. For example, the following image shows the E-767, the AWACS version of Boeing 767 operated by the JASDF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iknM3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iknM3.jpg&quot; alt=&quot;E-767&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:E-767_Japan_AWACS_112010.jpg#/media/File:E-767_Japan_AWACS_112010.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-767 Japan AWACS 112010&lt;/a&gt;&quot; by Jerry Gunner - AWACS Boeing E-767 of Hiko Keikai KanseitaUploaded by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Altair78&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Altair78&quot;&gt;Altair78&lt;/a&gt;. Licensed under CC BY 2.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is another matter if this is going to enter into service. My take would be that this is not going to happen in current time for a number of reasons including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The cost quoted is pretty high and downtime, too long.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;cutting up pressurized fuselage is not a good idea.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The concept is going to take up seats and increase weight for questionable benefits. What are you going to see up there? the same clouds that you are going to see from normal windows anyway.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-27T13:07:10.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23959" PostTypeId="2" ParentId="23942" CreationDate="2015-12-27T14:13:33.513" Score="7" Body="&lt;p&gt;The rocket engine produces the same thrust regardless of the speed it moves. Differently, the thrust of the jet engine depends on velocity and declines as velocity increases, because of the ram drag. It is largely useless if the engine speed approaches the exhaust velocity. The exact formula for efficiency can be found &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_engine#Thrust&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$ \eta_p = \frac{2}{1 + \frac{v_e}{v}} $$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, the rocket engine can produce significantly more thrust if the speed is really high. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2019-10-25T10:45:18.200" LastActivityDate="2019-10-25T10:45:18.200" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="23960" PostTypeId="2" ParentId="21624" CreationDate="2015-12-27T15:11:05.873" Score="1" Body="&lt;p&gt;The A-12's engines are podded partly for field replacement.  The port and starboard engines are IDENTICAL (not symmetrical).  That is to say, one of them is mounted upside down.  As a result, they are interchangeable and can be field swapped.  They built it so that if you have two A-12s stuck on the ground each with one bad engine, no matter which engine it is you can turn those into one A-12 with two good engines.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was designed for grimdark WW3 with Russia in Eastern Europe.  Its designers expected that it would be necessary to cobble damaged planes together at airstrips to continue the fight.  &lt;/p&gt;&#xA;" OwnerUserId="12791" LastActivityDate="2015-12-27T15:11:05.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23961" PostTypeId="2" ParentId="23942" CreationDate="2015-12-27T16:24:23.767" Score="5" Body="&lt;p&gt;The first, and most significant reason, is because more fuel is pumped in and burned.  Why does a car battery have more stored power than a AA battery?  Because, it is designed to be bigger, because that it necessary for the design requirements.&#xA;But, this is not always the case.  The mercury-redstone rocket, that carried Alan Shepard had 78,000 lbs of thrust, while the Boeing 777 can have up to 115,000 lbs of thrust per engine!&lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2015-12-27T16:24:23.767" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23962" PostTypeId="2" ParentId="12932" CreationDate="2015-12-27T17:15:37.293" Score="4" Body="&lt;p&gt;The only effect of a broken VOR antenna is that the polar pattern of the antenna will be altered, and its efficiency as an antenna decreased because it will be mismatched to the feed line. This means that you may only pick up the VOR when the &quot;good&quot; antenna element is closest to the beacon, and its lower efficiency will mean that the range from the beacon you get a signal will be decreased.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The navigation information is all carried in the 30 Herz modulation on the main carrier and the FM subcarrier: nothing in the VOR receiver ANTENNA can affect the phase relationships of the 30 Herz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the warning flag is not showing, there is adequate signal and the VOR bearing will be accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not good practice to leave an antenna broken in this way, but it is not an issue regarding safety as long as you've got enough signal (i.e. no warning flag).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Exactly the same applies if you're receiving an ILS localizer - the information is in the 90 and 150 Herz modulation in this case.  As long as the warning flag isn't showing the information WILL BE ACCURATE.&lt;/p&gt;&#xA;" OwnerUserId="12793" LastEditorUserId="12793" LastEditDate="2015-12-27T18:37:24.993" LastActivityDate="2015-12-27T18:37:24.993" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23963" PostTypeId="1" AcceptedAnswerId="23966" CreationDate="2015-12-27T17:37:12.533" Score="4" ViewCount="112" Body="&lt;p&gt;Would it be possible for a aircraft to deliver a payload into space using a turbojet-rocket hybrid? Merits are that they don't have to carry tons of oxidizer like a rocket would have to. It still may need to carry some but only when the atmosphere gets so thin. But even there is a lot of weight saving which means huge savings in fuel cost. Can Projects like the Skylon Space Craft really work or are they just fantasy?&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastActivityDate="2015-12-28T04:26:26.877" Title="Can Turborockets replace Pure Rockets?" Tags="&lt;engine&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ClosedDate="2015-12-30T23:04:13.767" ContentLicense="CC BY-SA 3.0" />
  <row Id="23965" PostTypeId="2" ParentId="23833" CreationDate="2015-12-27T22:16:19.377" Score="5" Body="&lt;p&gt;A Pelican tail is a V-tail with the two tail surfaces set apart. Compare this to a straight V-tail as that of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-117_Nighthawk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-117&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vV2FS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vV2FS.jpg&quot; alt=&quot;Tail view of the F-117&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail view of the F-117 (picture &lt;a href=&quot;http://www.aircraftresourcecenter.com/awa01/101-200/awa187-F-117/images_Steve_Bamford/F-117_04.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest to a Pelican tail which has actually been flown is maybe that of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop YF-23&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nsvNl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nsvNl.jpg&quot; alt=&quot;YF-23 tail view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail view of the YF-23 (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_YF-23&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearly, the distance between the two surfaces is dictated by the engines, but Northrop could have placed them on top of the nacelles. However, doing so would had been a poor choice for several reasons. A Pelican tail has those advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the vertical part is too close to the wing strake or fuselage chines, the strake vortex could hit the tail surfaces and cause oscillatory loads. &lt;a href=&quot;http://www.nytimes.com/1984/07/28/us/f-18-builder-says-test-missed-design-flaws.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The F-18 vertical tails needed to be reinforced&lt;/a&gt; so they would not break off. A Pelican tail should easily avoid this.&lt;/li&gt;&#xA;&lt;li&gt;A pure V-tail has &lt;a href=&quot;https://aviation.stackexchange.com/questions/9504/what-is-the-difference-between-the-v-shape-tail-and-the-straight-tail-on-the-bee/9509?s=1%7C0.0825#9509&quot;&gt;poor pitch damping&lt;/a&gt;, because the pitch-induced angle of attack change is reduced and the reaction force, too, by the V angle. Placing a horizontal strip in the middle improves pitch damping.&lt;/li&gt;&#xA;&lt;li&gt;Wikipedia has conflicting information on weight savings, but generally V- and Pelican tails should be more efficient than a conventional tail. However, for the best maneuverability a conventional tail is preferable. Again, placing a horizontal part between the two V surfaces improves pitch maneuverability, even when the control surfaces are only on the V part. Their symmetric deflection will induce a considerable lift change on the horizontal part.&lt;/li&gt;&#xA;&lt;li&gt;Placing the vertical tail outside and aft of the engine exhaust will shield the lateral IR radiation better.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The drawbacks are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Higher structural complexity compared to a true V-tail.&lt;/li&gt;&#xA;&lt;li&gt;Lower maneuverability and yaw damping than a conventional tail.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;I knew I had seen a Pelican tail before, but could not remember where. Now I found it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DlIQu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DlIQu.jpg&quot; alt=&quot;Fletter 282 V23&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This ist the German &lt;a href=&quot;https://en.wikipedia.org/wiki/Flettner_Fl_282&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fletter 282 V23&lt;/a&gt; helicopter (picture &lt;a href=&quot;http://ww2photo.se/air/d/flettner/08294.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;), and yes, this is a Pelican tail; however without control surfaces. It had two intermeshing rotors which made a tail rotor unnecessary. Anton Flettner had built the similar &lt;a href=&quot;https://en.wikipedia.org/wiki/Flettner_Fl_265&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flettner 265&lt;/a&gt; in 1940 and introduced the 282 in 1942. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2015-12-31T10:51:34.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23966" PostTypeId="2" ParentId="23963" CreationDate="2015-12-28T01:16:14.110" Score="4" Body="&lt;p&gt;Turborockets are hybrid systems that aim to use atmospheric oxygen as oxidizer instead of carrying it on board and thereby improve performance. While they do have a real chance of replacing the conventional rockets in use today, there are a number of &lt;em&gt;engineering&lt;/em&gt; challenges to be overcome before they become viable.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;These hybrid systems basically use a gas turbine inside the atmosphere (ramjets/scramjets have also been proposed) to produce thrust. The issue is that the jet engine becomes dead weight outside the atmosphere, so its weight has to be minimized. Skylon uses a slightly different method with a heat exchanger using helium, but the problem is the same.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The air intake has to operate over a wide range of speeds, from subsonic to hypersonic; the best option is to have a variable air intake, which adds weight and complexity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The nozzle has the same problem. The area ratio of the nozzle has to vary significantly to cope with widely differing flow conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the vehicle has to take off under its own power, it has to have lifting surfaces, which are dead weight (eating into payload) once out of the atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The integration of all these extra systems also causes a significant weight penalty.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The addition of all these systems increases weight more than the weight of the oxidizer they replace. This demands extremely high performance materials and very high efficiency systems for the vehicle to be commercially viable.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2658" LastEditDate="2015-12-28T04:26:26.877" LastActivityDate="2015-12-28T04:26:26.877" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23967" PostTypeId="2" ParentId="23609" CreationDate="2015-12-28T01:35:49.183" Score="7" Body="&lt;p&gt;Based on my personal experience, the answer is NO (as of the time of writing). I use both systems regularly, and have discovered the two do not share flight plans at the user account level. ForeFlight uses its own account (and not individual user accounts) to interact with Lockheed Martin Flight Services. Because of this, it appears that LMFS has no way of knowing which user account is associated with a flight plan filed through ForeFlight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Identifying data within the flight plan itself (i.e., name and phone) are not processed by the filing system, merely stored for later retrieval if needed. I mention this because LMFS can (upon request) associate tail numbers with a phone number, so that when you call them on 800-WX-BRIEF your profile comes up on their screen automatically (though I have found this to be less useful than one might think). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to use the services you have identified, you will need to file your flight plan directly on the LMFS web site (and have your notification settings configured properly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that said, all of these functions (with the exception SE-SAR), have been available directly within ForeFlight for some time:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ACAS/ATC notices - if configured by the user, sent via push notification (&lt;a href=&quot;http://blog.foreflight.com/2014/11/24/6-5-brings-flight-notifications-and-notam-advisor/&quot; rel=&quot;noreferrer&quot;&gt;http://blog.foreflight.com/2014/11/24/6-5-brings-flight-notifications-and-notam-advisor/&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EasyActivate/EasyClose - flight plans can be amended/canceled/activated/closed within the File &amp;amp; Brief window (&lt;a href=&quot;http://blog.foreflight.com/tag/flight-plan-filing/#attachment_4045&quot; rel=&quot;noreferrer&quot;&gt;http://blog.foreflight.com/tag/flight-plan-filing/#attachment_4045&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Close reminder - sent via push notification (&lt;a href=&quot;https://support.foreflight.com/hc/en-us/articles/205052928-What-are-push-notifications-&quot; rel=&quot;noreferrer&quot;&gt;https://support.foreflight.com/hc/en-us/articles/205052928-What-are-push-notifications-&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the past couple of years, ForeFlight has been aggressively working towards tighter integration with LMFS, so I would expect additional functionality to be forthcoming (purely speculative, since they are very tight-lipped about upcoming enhancements).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;UPDATE:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like LMFS now offers integrated services with a number of providers (but not ForeFlight). My guess is ForeFlight doesn't allow it because it was already offering the same services and now needs to figure out a way to ensure users don't get duplicate messages:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sZEbX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sZEbX.png&quot; alt=&quot;LMFS Service Provider Authorization screen&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="1968" LastEditDate="2015-12-28T03:42:08.177" LastActivityDate="2015-12-28T03:42:08.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23970" PostTypeId="1" AcceptedAnswerId="23971" CreationDate="2015-12-28T05:59:23.243" Score="29" ViewCount="4875" Body="&lt;p&gt;I was impressed to read &lt;a href=&quot;https://aviation.stackexchange.com/questions/23740/is-this-the-shortest-route-served-by-an-airbus-a320&quot;&gt;here&lt;/a&gt; that some passenger airline routes are even below 60 km in length. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even assuming that the passengers are already in the airport past the security check, probably a good bus could depart from the same gate and arrive to the destination gate in a very comparable time, as the plane still needs to taxi before and after the flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why these short haul flights are reasonable?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2018-05-26T20:17:40.200" Title="What is the rationale behind very short distance flights?" Tags="&lt;airline-operations&gt;&lt;short-haul&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="23971" PostTypeId="2" ParentId="23970" CreationDate="2015-12-28T11:16:51.573" Score="40" Body="&lt;p&gt;Because air travel is the best option in those places. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.amusingplanet.com/2013/08/worlds-shortest-commercial-flight-is.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;shortest commercial route in the world&lt;/a&gt; is between &lt;a href=&quot;https://en.wikipedia.org/wiki/Westray_to_Papa_Westray_flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;Westray and Papa Westray&lt;/a&gt; in the Orkney Islands, a distance of 1.7 miles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you see the &lt;a href=&quot;http://www.telegraph.co.uk/travel/travelnews/11541039/The-worlds-shortest-flights.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;list of short routes&lt;/a&gt;, almost all of them are between islands. That instantly rules out buses and the like unless a bridge is built, which in most cases is not commercially viable. One can use a boat or ferry, but in most cases, the sea may not be deep enough or calm enough.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="14897" LastEditDate="2018-05-26T20:17:40.200" LastActivityDate="2018-05-26T20:17:40.200" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23972" PostTypeId="1" AcceptedAnswerId="23975" CreationDate="2015-12-28T11:25:06.587" Score="10" ViewCount="2431" Body="&lt;p&gt;Slats can be &lt;a href=&quot;https://en.wikipedia.org/wiki/Leading-edge_slats#Types&quot;&gt;extended automatically&lt;/a&gt; depending on dynamic air pressure. Fly-by-wire systems provide flight envelop protection when flaps/slats are extended but I cannot find any reference of fly-by-wire feature such as auto-retractation/extension of flaps/slats depending on angle of attack or air-speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do systems to automatically retract/extend flaps depending on flight conditions (speed, angle of attack,dynamic pressure,...) exist?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="62" LastEditDate="2015-12-28T14:55:03.763" LastActivityDate="2015-12-28T14:55:03.763" Title="Do auto-flaps exist?" Tags="&lt;aircraft-systems&gt;&lt;flaps&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23973" PostTypeId="2" ParentId="23970" CreationDate="2015-12-28T11:58:03.207" Score="22" Body="&lt;p&gt;Most very short distance flights are flown between Islands. If you have a look at the list of such flight you can see they are places which are not or highly unlikely to be connected by a bridge which may be uneconomical. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the flights that are used on these routes are not the average airliners. They are aircrafts like De Havilland Twin Otter and Cessna Caravan propeller planes which are very efficient at relatively slow speeds and low altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATR42 &amp;amp; ATR72 are examples of large propeller planes in service. They are meant for short trips with the 72 having a max range of 1500km. They are also able to land in very short distances. Ideal for these island destinations&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastEditorDisplayName="user12782" LastEditDate="2015-12-29T17:39:54.947" LastActivityDate="2015-12-29T17:39:54.947" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23974" PostTypeId="2" ParentId="23972" CreationDate="2015-12-28T12:14:51.217" Score="9" Body="&lt;p&gt;Automatic flap control systems do exist. Boeing uses a system called Trailing edge load relief system, that automatically retracts flaps in case of excess airspeed. From &lt;a href=&quot;https://www.atsb.gov.au/media/24894/aair200202710_001.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATSB  Report 200202710&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Flap load relief system&lt;/p&gt;&#xA;&lt;p&gt;The flaps/slat electronics unit provided a trailing edge flaps load relief function that protected the flaps from excessive air loads. That function was operative at the FLAP 30 and FLAP 40 positions only. The flap lever did not move, but the flap position indicator displayed flap retraction and re-extension.&lt;/p&gt;&#xA;&lt;p&gt;When the flaps were set at FLAP 30, the trailing edge flaps:&lt;/p&gt;&#xA;&lt;p&gt;• retracted to FLAP 25 if the airspeed exceeded 176 kts&lt;/p&gt;&#xA;&lt;p&gt;• re-extended when the airspeed was reduced below 171 kts&lt;/p&gt;&#xA;&lt;p&gt;When the flaps were set to FLAP 40, the trailing edge flaps:&lt;/p&gt;&#xA;&lt;p&gt;• retracted to 30 if the airspeed exceeded 163 kts&lt;/p&gt;&#xA;&lt;p&gt;• re-extended when the airspeed was reduced below 158 kts&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Boeing 787 and Airbus &lt;a href=&quot;http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/a350-high-lift-devices-combine-simplicity-with-fuel-savings/&quot; rel=&quot;noreferrer&quot;&gt;A350 have systems&lt;/a&gt; that automatically adjust wing camber in flight using flaps to reduce drag. The &lt;a href=&quot;https://www.flightglobal.com/news/articles/variable-camber-to-cut-drag-207289/&quot; rel=&quot;noreferrer&quot;&gt;Boeing system&lt;/a&gt; is called trailing edge variable camber (TEVC).&lt;/p&gt;&#xA;&lt;p&gt;Of course the flaps are controlled by the computer in a number of combat aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Actually automatic flaps are not new. The &lt;a href=&quot;http://www.constable.ca/caah/breguet.htm&quot; rel=&quot;noreferrer&quot;&gt;Breguet XIV had them&lt;/a&gt; in the lower wing. Basically, the flaps (called 'Equalizer flaps') were hinged to the rear spar and were maintained at a given angle using rubber cords, which permitted them to vary with wind pressure.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-28T12:14:51.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23975" PostTypeId="2" ParentId="23972" CreationDate="2015-12-28T12:48:35.667" Score="18" Body="&lt;p&gt;It can be much simpler than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerobatic glider Mü-28 has a symmetric airfoil with 20% flaps, and those flaps are automatically set as a function of the g-load experienced near the center of gravity and the dynamic pressure. Basically, a spring-suspended lever with a mass at the end creates the necessary control input. In straight flight they are deflected downwards which makes the airfoil more suitable for gliding, in a zero-g parabola or in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/12383/can-you-fly-an-airplane-at-a-90-roll-angle-without-losing-altitude/12386#12386&quot;&gt;knife-edge flight&lt;/a&gt; they are moved to 0° deflection, and in inverted flight they show a negative deflection angle. If flight speed increases, the deflections become proportionally smaller, thus preventing overloading the airframe (which is dimensioned for ±10g, so overloading it is hard anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4XqKn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4XqKn.jpg&quot; alt=&quot;Mü-28 in inverted flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mü-28 in inverted flight (picture &lt;a href=&quot;http://www.sagach.ch/images/mue28_3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Thanks to the low sun the rear part of the fixed wing section is illuminated so the negative flap deflection is easy to discern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.snipview.com/q/Akaflieg_M%C3%BCnchen_M%C3%BC28&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This innovative automatic flap system fitted to the Mü28 was developed&#xA;  at the Flugwissenschaftliche Vereinigung Aachen under the project&#xA;  designation FVA-21, controlling the position of the flaps, depending&#xA;  on the speed and the load factor, so that the aircraft flies with&#xA;  optimal angle of attack in all flight conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Scheduling the maximum deflection angle with dynamic pressure as an overload protection can thus be done in two ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Fully mechanically by adding a spring element in the flap linkage.&lt;/li&gt;&#xA;&lt;li&gt;In a fly-by-wire control system by hard-coding it into the control laws. For faster airplanes this is preferred as it does not require a spring in the system - any elasticity will at some point cause &lt;a href=&quot;https://aviation.stackexchange.com/questions/275/what-causes-aileron-and-elevator-flutter&quot;&gt;flutter&lt;/a&gt;, this is only a question of speed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-12-28T12:48:35.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23976" PostTypeId="2" ParentId="23740" CreationDate="2015-12-28T14:07:13.603" Score="3" Body="&lt;p&gt;I don't think so. The shortest route with an A319, which is an A320 family aircraft that I am aware of is Dar es Salaam - Zanzibar (HTDA, HTZA) which if I recall is roughly 73 kilometers (probably even less from airport to airport) operated by FastJet Tanzania.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source &lt;a href=&quot;http://www.fastjet.com/us/en/destinations&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2015-12-28T14:07:13.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23977" PostTypeId="1" AcceptedAnswerId="23986" CreationDate="2015-12-28T15:29:29.523" Score="30" ViewCount="5799" Body="&lt;p&gt;I was discussing helicopter control with relatives over the holidays, particularly regarding how difficult it is to fly one and how changing any control requires adjusting the other two main controls. One of my relations asked whether any helicopters have a computer control system that automatically compensates, allowing simplified controls that almost anyone could fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I replied that I had not heard of such a thing and could only guess why not:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Reliability concerns and possibly pilot training concerns (i.e., you'd have to know how to really fly in the event of a computer failure anyway, so why even have the computer?)  &lt;/li&gt;&#xA;&lt;li&gt;Subtle complexities of the control interactions not lending themselves to reasonable computer automation.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Are there actually no systems like this? Why not? Were my guesses any good?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the &lt;a href=&quot;https://aviation.stackexchange.com/questions/15462/do-rotorcrafts-like-helicopters-have-autopilots&quot;&gt;possible duplicate&lt;/a&gt;, I saw that question and it seems to indicate that automatic simplified controls would be possible, but it doesn't seem to fully answer the question of why not have a psuedo autopilot that allows a pilot to just push forward on the cyclic to go forward (for example) without having to constantly adjust the collective and rudder at the same time.&lt;/p&gt;&#xA;" OwnerUserId="8848" LastEditorUserId="14897" LastEditDate="2019-08-12T15:11:22.377" LastActivityDate="2019-08-14T08:40:52.593" Title="Why aren't there simplified fly-by-wire helicopter controls?" Tags="&lt;helicopter&gt;&lt;flight-controls&gt;&lt;fly-by-wire&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="23978" PostTypeId="2" ParentId="23977" CreationDate="2015-12-28T17:57:55.910" Score="9" Body="&lt;p&gt;There are two extremes:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;No augmented controls, i.e. most normal aircraft. Pilot controls control surfaces and engines directly.&lt;/li&gt;&#xA;&lt;li&gt;Heavily augmented controls (left, right, up down shifts exactly like that), like quadcopters. Pilot gives command how the aircraft should move that is translated by algorithm into control surface and engine inputs.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;At either of the two extremes, stuff is decently well understood. It's when you go in between that it starts becoming problematic.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Augmented Controls&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;There is always a conflict between a beneficial change making flying easier for the pilot and a greater level of abstraction from the flight controls. One place where this is particularly prevalent is on Airbus aircraft, where misunderstandings between the pilot, interface, control and aircraft have lead to multiple accidents.&lt;/p&gt;&#xA;&lt;p&gt;Simon's point here- what do you 'want' you control surfaces to do- is very relevant.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Dynamic System&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Helicopters are incredibly dynamic. For instance, a sideways gust will push the helicopter to the side, but that would also result in a disproportionate rotation on the whole airframe caused by the surface area of the tail rotor fin. Yet the pure sideways (not moment) force from increasing the tail rotor power is uncompensated and would require main rotor adjustment again to stay in position. Any pilot response and input would have to be handled appropriately to prevent pilot induced oscillation.&lt;/p&gt;&#xA;&lt;p&gt;Stability Augmentation is used, for instance on the EC135:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The Auto Flight System is hierarchical in concept and on G-IWRC comprised a three axis Stability Augmentation System (SAS) and an autopilot. The SAS consisted of a  Pitch  and  Roll  SAS  (P&amp;amp;R  SAS)  and yaw  SAS.   The helicopter  was  also  equipped  with  a  pitch  damper.  These systems are used for stabilising the attitude of the helicopter  about  the  longitudinal,  lateral  and  yaw  axes by applying limited authority inputs to the main controls.&lt;/p&gt;&#xA;&lt;p&gt;The  SAS  system  is  designed  for  ‘hands-on’  operation, which means that the pilot must provide control inputs through  the  cyclic  control  and  yaw  pedals  in  order to  control  the  attitude  of  the helicopter.    The  SAS  is automatically  activated  during  the  start  procedures  and can be disengaged by pressing either of the SAS DCPL&#xA;switches  located  on  top  of  each  cyclic  stick  grip. Re-engagement of the SAS is through a four-way switch on the cyclic grip, labelled P&amp;amp;R/P – P/y RST. &lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/5422f825ed915d13710006a9/Eurocopter_EC135_T2__G-IWRC_09-08.pdf&quot; rel=&quot;noreferrer&quot;&gt;Eurcopter EC135 Accident Report&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Pilot Role and Regulatory Aspects&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;I've worked on UAV systems that go 'the whole way' on control automation. I think part of the problem is the conservative opinion on the role of the pilot. Airbus have become heavily criticized for their design choices that are supposed to make it easier for the pilot to fly. Augmenting flight controls is risky business.&lt;/p&gt;&#xA;&lt;p&gt;Changes are difficult to implement and testing expensive in the aviation sector. We could ultimately remove the pilot and whoever onboard (doctor, nurse) could just select a spot on a map as a landing site. By going to the stage of making push up/down/left/right... controls as you suggest, we have created fully automatic flight controls. It is (entirely) technically feasible, since that's what the autopilot does. Changing how active control inputs are interpreted from a use, licensing, training and execution standpoint is a whole different story.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-28T19:39:58.740" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="23979" PostTypeId="1" AcceptedAnswerId="23980" CreationDate="2015-12-28T18:03:01.883" Score="21" ViewCount="6248" Body="&lt;p&gt;How harmful is the fluid applied on aircraft to the environment? Is there any way to collect this waste fluid to minimize this, if in fact it is harmful?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="2923" LastEditDate="2015-12-28T21:09:08.270" LastActivityDate="2018-11-28T16:25:01.323" Title="Is deicing fluid harmful to the environment?" Tags="&lt;deice&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23980" PostTypeId="2" ParentId="23979" CreationDate="2015-12-28T18:22:23.487" Score="20" Body="&lt;p&gt;The main component of deicing fluid is either Ethylene Glycol (EG, toxic) or Propylene Glycol (PG, non-toxic) (&lt;a href=&quot;https://en.wikipedia.org/wiki/Deicing_fluid&quot;&gt;source&lt;/a&gt;) and depending on the category applied different amounts are used annually. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been &lt;a href=&quot;http://www.huntsman.com/performance_products/Media%20Library/a_MC348531CFA3EA9A2E040EBCD2B6B7B06/Products_MC348531D0B9FA9A2E040EBCD2B6B7B06/Glycols_MC348531D11A3A9A2E040EBCD2B6B7B06/files/fate_and_effects.pdf&quot;&gt;studies of the environmental impact of deicing fluid&lt;/a&gt;, which basically states:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In water, EG is not persistent and biodegrades aerobically and anerobically.&lt;/li&gt;&#xA;&lt;li&gt;In air, EG is not readily volatile and its atmospheric half-life is approximately 1 day&lt;/li&gt;&#xA;&lt;li&gt;In soil EG is also not persistent and biodegrades anerobically in about 1 day&lt;/li&gt;&#xA;&lt;li&gt;EG is disposed of and treated at standard wastewater plants&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(I think the above comments also apply to PG, but somebody will have to confirm that since I can't find anything that mentions it).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PG is non-toxic and is used in quite a few products that you use every day, from pharmaceuticals to food additives and moisturizers. I can't confirm but one of the linked articles says that most of the DI fluid used in the US is PG based, which I would believe, but can't source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And from the article quoting an &lt;a href=&quot;http://www.epa.gov/sites/production/files/2015-06/documents/airport-deicing-pds-2000.pdf&quot;&gt;EPA Report 821-R-00-0016, January 2000, Revised August 2000&lt;/a&gt;, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although EPA does not use such a system, the&#xA;  U.S. Fish and Wildlife Service Classification&#xA;  System for Acute Exposures defines ‘relatively&#xA;  harmless’ as any chemical with an LC50 above&#xA;  1,000 mg/L. The test results … indicate that&#xA;  ethylene glycol and propylene glycol may be&#xA;  classified as ‘relatively harmless,’as defined by&#xA;  the U.S. Fish and Wildlife Service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is also one manufacturer using &lt;a href=&quot;https://en.wikipedia.org/wiki/1,3-Propanediol&quot;&gt;1,3-propanediol&lt;/a&gt; which is a by-product of corn fermentation and should be relatively minor as far as environmental impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also considerable movement in airports to &quot;go green&quot; and &lt;a href=&quot;http://www.airportsgoinggreen.org/Presentations/2012-Presentations/Pecha%20Kucha/ThermoEnergy_AGG%202012.pdf&quot;&gt;recover used deicing fluid&lt;/a&gt;, especially considering that a larger aircraft can take more than 1000 gallons of diluted deicing solution at the rate of up to $12/gallon, quite a bit of which runs off the aircraft and onto the ground. &lt;a href=&quot;http://www.epa.gov/eg/airport-deicing-effluent-guidelines&quot;&gt;In fact, the EPA has mandated that new airports in cold climates recover 60% of DI fluid.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;&#xA;&lt;strong&gt;Edit&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It may be important to note that the point of DI fluid is to keep the snow/ice off the aircraft until it leaves the ground, not assist in flight into known ice. Depending on the fluid applied, they usually only stay on until the aircraft reaches about 100kts. This means that most of the applied DI fluid is going to end up in the airports wastewater system because most will run off the aircraft on the ramp/apron, not spread around the countryside as the aircraft flies around. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-28T22:07:23.453" LastActivityDate="2015-12-28T22:07:23.453" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23981" PostTypeId="1" CreationDate="2015-12-28T18:31:50.777" Score="6" ViewCount="5393" Body="&lt;p&gt;Which method is used to measure the runway conditions? &#xA;Is it impossible to land on a contaminated runway?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="8576" LastEditDate="2015-12-28T21:08:13.030" LastActivityDate="2016-04-22T20:39:15.117" Title="How are runway conditions measured?" Tags="&lt;runways&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23982" PostTypeId="2" ParentId="23981" CreationDate="2015-12-28T19:35:32.460" Score="16" Body="&lt;p&gt;&lt;strong&gt;Measurement&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runway conditions are measured using a friction standard: &lt;a href=&quot;https://www.iata.org/iata/RERR-toolkit/assets/Content/Contributing%20Reports/ICAO_Circular_on_Rwy_Surface_Condition_Assessment_Measurement_and_Reporting.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Circular 329&lt;/a&gt;, Runway Surface Condition Assessment, Measurement and Reporting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Local regulation applies too, e.g. for UK: &lt;a href=&quot;https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/398400/RA3272_Initial_Issue.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;RA 3272&lt;/a&gt; – Continuous Friction Measuring Equipment.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Adequate runway friction characteristics are needed for three distinct&#xA;  purposes:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;deceleration of the aeroplane after landing or a rejected take-off;  &lt;/li&gt;&#xA;  &lt;li&gt;maintaining directional control during the ground roll on take-off&#xA;  or landing, in particular in the presence of cross-wind, asymmetric&#xA;  engine power or technical malfunctions;  &lt;/li&gt;&#xA;  &lt;li&gt;wheel spin-up at touchdown.  &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.icao.int/APAC/Meetings/2012_APRAST/ICAO%20APRAST-2%20RCR.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt; -- Source also used for most of the technical details in this post)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Continuous Friction Measuring Device / Equipment (CFMD / CFME)  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nfnIb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nfnIb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.team-eagle.ca/equipment/douglas-spd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Team Eagle&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bv1W8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bv1W8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.icao.int/APAC/Meetings/2012_APRAST/ICAO%20APRAST-2%20RCR.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Decelerometer, Brakemeter, Dynometer... for snow and ice.  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9kX71.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9kX71.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.sherwinindustriesinc.com/sherwin/virtuemart/130.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sherwin Industries&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Minimum Friction Level (MFL) μ is specified by local air authority. A value less than 0.34 is seen by ICAO as slippery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Friction is measured for each third of the runway, in a direction parallel to the runway centerline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9Zljj.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9Zljj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.icao.int/APAC/Meetings/2012_APRAST/ICAO%20APRAST-2%20RCR.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Reporting&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Runway friction coefficient should be measured at least daily and reported via NOTAM if needed. NOTAM codes for friction measurement equipment:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;BOW Bowmonk Decelerometer&lt;/li&gt;&#xA;&lt;li&gt;BRD Brakemeter-Dynometer&lt;/li&gt;&#xA;&lt;li&gt;ERD Electronic Recording Decelerometer&lt;/li&gt;&#xA;&lt;li&gt;GRT Griptester&lt;/li&gt;&#xA;&lt;li&gt;MUM Mark 4 Mu Meter&lt;/li&gt;&#xA;&lt;li&gt;RFT Runway friction tester&lt;/li&gt;&#xA;&lt;li&gt;SFH Surface friction tester (high pressure tire)&lt;/li&gt;&#xA;&lt;li&gt;SFL Surface friction tester (low pressure tire)&lt;/li&gt;&#xA;&lt;li&gt;SKH Skiddometer (high pressure tire)&lt;/li&gt;&#xA;&lt;li&gt;SKL Skiddometer (low pressure tire)&lt;/li&gt;&#xA;&lt;li&gt;TAP Tapley Decelerometer&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A contamination terminology is used for a qualitative description of the runway condition. It can be used in complement of the friction coefficient value, or alone when a measure is not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sample for water on the runway:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;DAMP: the surface shows a change of colour due to moisture.&lt;/li&gt;&#xA;&lt;li&gt;WET: the surface is soaked but there is no standing water.&lt;/li&gt;&#xA;&lt;li&gt;WATER PATCHES: significant patches of standing water are visible.&lt;/li&gt;&#xA;&lt;li&gt;FLOODED: extensive standing water is visible.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Other terms exist for snow, ice, etc.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A runway or portion thereof shall be determined as being slippery when&#xA;  wet when the measurements with a CFME + self wetting tyre shows that&#xA;  the runway surface friction characteristics are below the minimum&#xA;  friction level specified by the State.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;NOTAM sample:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;NOTAN A1713/11 Chennai Airport ( VOMM ),  India&#xA;A1713/11 1111220910/1112231200 EST RWY&#xA;RWY 07/25 LIABLE TO BE SLIPPERY WHEN WET.&#xA;THE VALUE OF COEFFICIENT OF FRICTION IS BLW &#xA;THE NOTIFIED VALUE OF 0.34 FOR RWY 07/25&#xA;IN SECTION AS BLW :-&#xA;RWY07 BTN 400M AND 650M&#xA;RWY25 BTN 300M AND 500M&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;As commented by @RonBeyer (thanks!), pilots can also provide their own observations about braking conditions to ATC using PIREPS. PIREPS are voluntary reports by pilots to share information with ATC and other pilots. They are valued because they are current and they may be the only information available at small airfields. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC and recorded bulletins provide runway conditions to pilots, in addition of NOTAM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Impact on roll distance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Weather has many impact on operations, but runway contamination particularly impacts landings, due to the loss of braking capacity. Take-off are also impacted, mostly at the beginning of the take-off roll, when the control surfaces are not active. Runway condition is also important to take into account if a take-off has to be rejected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A degraded runway condition decreases the longitudinal stability and increases the roll distance:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UAiFH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UAiFH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Note: As mentioned by @Yos233, autobrake LOW and MEDIUM have been inverted&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://flightsafety.org/files/alar_bn8-5-wetrwy.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust reversers are particularly useful when the runway is not dry:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QGzsM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGzsM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Note: Autobrake LOW and MEDIUM still inverted&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://flightsafety.org/files/alar_bn8-5-wetrwy.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots will use similar tables to determine if they can land or take-off. A flight management computer can also be fed with the runway condition for roll distance determination..&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft are tested for their ability to cope with different runway conditions:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QSTS9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QSTS9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;A340 test on artificially flooded runway (&lt;a href=&quot;http://aviationclub.aero/group/tech-log/photo/4033/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that it is possible to land and take-off quite easily on compacted snow -- and, albeit more difficult, on ice -- taking into account the coefficient of friction:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hel50.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hel50.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Alton Bay runway (&lt;a href=&quot;http://isserfiq.blogspot.fr/2014/02/a-cold-febuary-flight.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;More&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://ntl.bts.gov/lib/1000/1100/1106/wrfmrwg1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Description of Various Friction-Measuring Equipment&#xA;Used in Winter Operations&lt;/a&gt; (appendix A)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="13197" LastEditDate="2016-04-22T20:39:15.117" LastActivityDate="2016-04-22T20:39:15.117" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23983" PostTypeId="2" ParentId="23977" CreationDate="2015-12-28T20:39:05.260" Score="1" Body="&lt;p&gt;On main consequence of having independent controls in a helicopter is that the same control movement will have different outcome depending on the movement of other controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, consider the collective- in hover, varying the collective will result in a change in altitude, while in forward flight, the same thing will result in either a change in altitude or speed depending on how the cyclic is moved. The operation of cyclic has similar results based on operation of other controls. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the problem in having pseudo or coupled controls- the helicopter response &lt;em&gt;may&lt;/em&gt; differ from that of the intended one. On the other hand, the FBW computer is pretty straightforward- you input the controls, which are sent to the actuators through computer. The computer need not guess what you want to do here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think there are some helicopters where &lt;a href=&quot;https://www.flightglobal.com/news/articles/intrepid-explorer-57510/&quot; rel=&quot;nofollow&quot;&gt;moving collective automatically adjusts the torque&lt;/a&gt;, though this is the only case where I think the controls are coupled.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-28T20:39:05.260" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23984" PostTypeId="2" ParentId="23970" CreationDate="2015-12-28T22:14:31.677" Score="10" Body="&lt;p&gt;One point not yet mentioned is that most of these short flights are not just between islands, but in archipelagoes. So an aircraft may be dearer to run than a ferry, but the aircraft can do six or seven journeys a day (e.g. Westray to Papa Westray and back, Westray to Mainland, Mainland to Hoy...) and save the costs of three or four ferries. &lt;/p&gt;&#xA;" OwnerUserId="12807" LastActivityDate="2015-12-28T22:14:31.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23985" PostTypeId="2" ParentId="23955" CreationDate="2015-12-29T00:08:30.730" Score="2" Body="&lt;p&gt;To answer this question, it is best to start with the compression work which has to be performed on the air flowing through the engine. If you just want to know how much power is needed to run the fan on a mid-sized passenger jet, you can look at &lt;a href=&quot;http://www.readbag.com/soljet-pdfs-rr-se-fs-rb211&quot; rel=&quot;nofollow&quot;&gt;industrial installations&lt;/a&gt; of the &lt;a href=&quot;http://www.iasg.co.uk/pdfs/articles/engine_services/Pages%20from%20CAVR_September_2005.pdf&quot; rel=&quot;nofollow&quot;&gt;Rolls-Royce RB-211&lt;/a&gt;, two of which power the Boeing 757 and four the Boeing 747-200. The electrical output comes directly from the low pressure turbine which would drive the fan in an airliner engine, and is up to 32 MW for the RB-211 (after generation losses).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to the core compressor: If we assume that no heat is exchanged between the gas and the surroundings we can use the formulas for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Adiabatic_process#Example_of_adiabatic_compression&quot; rel=&quot;nofollow&quot;&gt;adiabatic process&lt;/a&gt; as presented in Wikipedia. The example given is actually a nice fit for the RB-211-535 or an EJ-200 engine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initial state (Index 0): 27°C/300 K and 1 bar/100 kPa&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Final state (Index 1): 477°C/751 K and 25 bar/2500 kPa, 10% of the initial volume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When we use &lt;a href=&quot;https://en.wikipedia.org/wiki/Gas_compressor#Thermodynamics_of_Gas_Compression&quot; rel=&quot;nofollow&quot;&gt;this Wikipedia page&lt;/a&gt;, we get:&#xA;$$W = \frac{\kappa\cdot R\cdot(T_1 - T_0)}{\kappa - 1} = \frac{\kappa\cdot R\cdot T_0}{\kappa - 1}\cdot\left(\left(\frac{P_1}{P_0}\right)^{\frac{\kappa - 1}{\kappa}} - 1\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $R$ = 287 $\frac{J}{kgK}$ is the &lt;a href=&quot;http://www.efunda.com/materials/common_matl/show_gas.cfm?MatlName=Air0C&quot; rel=&quot;nofollow&quot;&gt;gas constant&lt;/a&gt; and $\kappa$ = 1.4 for diatomic gasses like nitrogen and oxygen.. $V_0$ of 1 kg of air is 0.84 m³ and $V_1$ is 0.084 m³. The result is $W$ = 454 kJ per kg of air, and that has now to be multiplied with the mass flow. For the RB-211 I find mass flow data only for industrial applications where the engine runs at a reduced pressure ratio, but I will use the 203 - 212 kg/s regardless because it fits with the initial pressure and temperature data of my example. The result is in the order of 95 MW in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_RB211&quot; rel=&quot;nofollow&quot;&gt;200 kN thrust class engine&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering that the above equations are for the ideal, friction-less case, the true power need is probably 10% - 20% higher. However, at altitude the air density is only a quarter of that at sea level, so the compressor power needs are also only a quarter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To put it into proportion, we need flight speed as well: At 240 m/s the 50 kN thrust at altitude translate into 12 MW of propulsive power, so the compressor power under the same conditions is twice as high.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-29T10:03:58.077" LastActivityDate="2015-12-29T10:03:58.077" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23986" PostTypeId="2" ParentId="23977" CreationDate="2015-12-29T07:03:05.893" Score="34" Body="&lt;p&gt;Helicopter manufacturers seem to have been slow to adopt fly-by-wire systems. I used to work in the General Dynamics group which designed the fly-by-wire system for the F-16. That was the first production aircraft which had full-authority fly-by-wire (without mechanical backup systems). By the time I started working there, they were in process of updating the system to incorporate a digital flight control computer. The production required extensive coordination between multiple disciplines. As an electrical engineer, I regularly interacted with software engineers, control-law designers, test engineers, and &quot;mechanization&quot; engineers. It took many years for the company to develop such a culture, where each member is concerned with the efficiency and safety of the aircraft. I speculate the helicopter manufacturers didn't catch up for a couple of decades because funding was limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an article which describes the Army's experience: &lt;a href=&quot;http://web.archive.org/web/20111020165113/http://www.nationaldefensemagazine.org/archive/2011/April/Pages/ArmySlowToAdaptFly-by-WireControlsforHelicopters.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Army Slow To Adapt Fly-by-Wire Controls for Helicopters&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Funding aside, helicopters are ideal candidates for fly-by-wire systems. The obvious goal is to take a marginally controllable aircraft and make it both stable and maneuverable. That would dramatically reduce pilot workload. Most helicopter fly-by-wire systems accomplish hands-free hover and decoupled control inputs (i.e. sideways flight without needing rudder inputs).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first helicopter which demonstrated a great fly-by-wire system was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing%E2%80%93Sikorsky_RAH-66_Comanche&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sikorsky RAH-66&lt;/a&gt;. It even achieved sideways flight at 60 knots and backward flight at 25 knots, using only cyclic stick inputs. Unfortunately, that program was cancelled in 2004. The first production military fly-by-wire helicopter is the &lt;a href=&quot;https://en.wikipedia.org/wiki/NHIndustries_NH90&quot; rel=&quot;nofollow noreferrer&quot;&gt;NHIndustries NH90&lt;/a&gt;, which was the first helicopter to fly without mechanical backup controls, in 2002, and entered service in 2007. The first civilian fly-by-wire helicopter, the &lt;a href=&quot;http://www.bell525.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bell 525&lt;/a&gt; is currently under development.&lt;/p&gt;&#xA;" OwnerUserId="12812" LastEditorUserId="23223" LastEditDate="2019-08-14T08:40:52.593" LastActivityDate="2019-08-14T08:40:52.593" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="23987" PostTypeId="1" AcceptedAnswerId="23994" CreationDate="2015-12-29T07:50:29.330" Score="13" ViewCount="3834" Body="&lt;p&gt;I was motivated by another SE Aviation Question where the complex set of manouveres needed to land the space shuttle is described to ask the following question: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the landing handled manually or is there an auto landing system? I suppose there is a high fidelity simulator to train all this on? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder if that simulation engine has gotten into any of the enthusiast flight simulator software?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21981/how-does-the-space-shuttle-slow-down-on-the-re-entry-descent-and-landing/23889?noredirect=1#comment55762_23889&quot;&gt;How does the space shuttle slow down on the re-entry, descent, and landing?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-26T08:28:38.110" Title="Was the Space Shuttle landing sequence executed manually or automatically?" Tags="&lt;landing&gt;&lt;flight-simulator&gt;&lt;space-shuttle&gt;&lt;autoland&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23988" PostTypeId="1" AcceptedAnswerId="23989" CreationDate="2015-12-29T07:57:14.693" Score="6" ViewCount="423" Body="&lt;p&gt;We know that many Space Shuttles / Rockets etc. carry their own oxidizer with them. This is partly because at the heights they operate the atmosphere is too rarefied to have enough oxygen to sustain the combustion rates they need. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But also, the liquid oxidizer means small pumps can be used instead of massive compressor stages. Which motivates the following question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it be feasible for a typical passenger jet to carry along its own Oxidizer? I am looking for a back of the envelope feasibility calculation. It intuitively sounds impractical but I'm just curious to see some back of the envelope estimates of how much ( weight / volume) of Liq. O2 tanks would be needed if we hypothetically had something like a B-747  with its own cryogenic Oxygen tanks in addition to already extant massive fuel tanks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Partially motivated by this related SE Aviation Question and a comment by User @Freeman:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/23942/how-do-rocket-engines-produce-more-thrust-than-aircraft-jet-engines/23949?noredirect=1#comment55737_23949&quot;&gt;How do rocket engines produce more thrust than aircraft jet engines?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-09-19T15:13:23.577" Title="Would it be feasible for a typical passenger jet to carry along its own Oxidizer?" Tags="&lt;fuel&gt;&lt;theory&gt;&lt;propulsion&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="23989" PostTypeId="2" ParentId="23988" CreationDate="2015-12-29T09:02:25.160" Score="5" Body="&lt;p&gt;Short answer: Yes for a short-range airliner, but it would cost a couple of seat rows. No for long-range travel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer answer: To burn 1 kg of Kerosene you need &lt;a href=&quot;http://www.brighthub.com/environment/renewable-energy/articles/90254.aspx&quot; rel=&quot;nofollow&quot;&gt;15.6 kg of air&lt;/a&gt; or 3.59 kg of O$_2$. Its &lt;a href=&quot;https://en.wikipedia.org/wiki/Liquid_oxygen&quot; rel=&quot;nofollow&quot;&gt;density as a liquid&lt;/a&gt; is 1.14 kg/l, so it will use 2.65 times the volume of fuel. A cryogenic tank with sufficient insulation is required, though. This means it should have as little surface area per volume as possible. You could not put the LOX into the wing tanks, but need something with a spherical shape somewhere in the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a large commercial &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow&quot;&gt;airliner needs 100 tons of fuel&lt;/a&gt;, it would need to add 359 tons of oxygen. This would be already close to its own takeoff mass, so adding the oxygen will make the airplane too heavy. If, however, you are content with a short-range version of the same airliner that consumes just 20 tons of kerosene for its trip, the needed 72 tons of LOX would require a volume of 63 m³ which is equal to a sphere of 5 m diameter. This would fit nicely into the cabin of a wide body airliner and allow for some insulation. For cg reasons the tank would be right after the wing spar carrythrough, so the airliner would have two short cabins, one ahead and one aft of the tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry, the 747 hump cannot be used for LOX storage - the cg shift would be too big.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For running regular jet engines you would still need lots of process gas. To carry that along as well is impossible, even for a short hop. Process gas is all the nitrogen and extra oxygen which is compressed, heated and then ducted through the turbines and accelerated on the way out, but does not actively take part in the combustion. Without that mass of gas thrust would be much lower, or the exhaust speed would need to be much higher for the same thrust, turning the engine into a rocket.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2015-12-29T14:25:46.373" LastActivityDate="2015-12-29T14:25:46.373" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="23990" PostTypeId="1" AcceptedAnswerId="27079" CreationDate="2015-12-29T09:03:30.990" Score="13" ViewCount="1431" Body="&lt;p&gt;&lt;a href=&quot;https://www.telegraph.co.uk/news/worldnews/australiaandthepacific/newzealand/12070797/Malaysia-Airlines-pilot-realises-plane-is-flying-in-the-wrong-direction-after-8-minutes.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Malaysian MH132&lt;/a&gt; seems to have had a bit of a mix up over flight plans.  It appears to be a non-event but it does make me wonder if &quot;gross error checks&quot; are commonly used by airline pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm only a PPL(H), but gross error checks are built in to me from training. For example, &quot;after setting off on the first leg, the compass should be pointing NE which means the town should be on my right and the river on my left&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some commentators have remarked that the captain did a &quot;great job&quot; in recognising the unexpected heading and querying it.  To me, it seems like basic airmanship to recognise and query it and leads me to also wonder if the crew studied the route during pre-flight and after it was loaded into the FMC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can any airline pilots add facts to the story?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="14897" LastEditDate="2019-03-27T00:28:21.310" LastActivityDate="2019-03-27T00:28:21.310" Title="Do airline pilots routinely carry out &quot;gross error&quot; checks?" Tags="&lt;airline-operations&gt;&lt;navigation&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="23991" PostTypeId="2" ParentId="23987" CreationDate="2015-12-29T09:40:28.743" Score="2" Body="&lt;p&gt;Both manual and computer control were possible in all phases, but re-entry was done by computer (with manual control available as a contingency, and tested once on STS-2), while approach was almost always done manually.  No landings were ever done by computer.  &lt;a href=&quot;https://en.wikipedia.org/wiki/STS-3&quot; rel=&quot;nofollow&quot;&gt;STS-3&lt;/a&gt; used the autopilot (with some issues) on descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;STS-53 was to have &lt;a href=&quot;https://waynehale.wordpress.com/2011/03/11/breaking-through/&quot; rel=&quot;nofollow&quot;&gt;tested autoland&lt;/a&gt;, but the test was cancelled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After Columbia, further modifications were made so that with the installation of a cable to connect certain systems, the shuttle could execute re-entry, descent, and landing without pilots.  This enabled remote control of operations that would otherwise require switches to be thrown on the flight deck.&lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="3159" LastEditDate="2015-12-29T10:17:53.507" LastActivityDate="2015-12-29T10:17:53.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23992" PostTypeId="2" ParentId="23987" CreationDate="2015-12-29T09:47:58.657" Score="0" Body="&lt;p&gt;After the reentry burn, most of the atmospheric reentry and descent was handled automatically. (Exception: &lt;a href=&quot;https://en.wikipedia.org/wiki/STS-2&quot; rel=&quot;nofollow&quot;&gt;STS-2&lt;/a&gt; was flown manually for much of the descent to collect additional data on the re-entry behaviour in various conditions.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the landing, shuttle commanders were encouraged to take over at the end, after the speed had dropped below Mach 1, to get the &quot;feel&quot; and land manually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard that the entire landing &lt;strong&gt;could&lt;/strong&gt; be performed automatically, except for the lowering of the landing gear.  For some reason this has always been under crew control.  (I can't find a reference for this though.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simulators, I assume a ground simulator was available.  However crew also practiced on &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Training_Aircraft&quot; rel=&quot;nofollow&quot;&gt;modified Gulf Stream&lt;/a&gt; aircraft that could be set up to fly with a similar approach to the real shuttle.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2015-12-29T09:47:58.657" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="23994" PostTypeId="2" ParentId="23987" CreationDate="2015-12-29T09:58:34.260" Score="20" Body="&lt;p&gt;Since that's really three questions, I'll address them separately.&lt;/p&gt;&#xA;&lt;h1&gt;1. Did the shuttle have or use autoland?&lt;/h1&gt;&#xA;&lt;p&gt;The space shuttle did have autoland capability, in theory. When the shuttle was being developed, it was imagined that flights could last so long that human pilots might get rusty, or have their ability to function under gravity impaired due to muscle atrophy from extended time in micro gravity.&lt;/p&gt;&#xA;&lt;p&gt;Unfortunately, testing autoland on the space shuttle was a bit risky. If anything went wrong, the shuttle has no ability to disengage and go-around, and it might be too late for a human pilot to intervene and still make a safe landing.&lt;/p&gt;&#xA;&lt;p&gt;They did try evaluating an incomplete implementation of the autoland on STS-3, where the lineup, final approach (outer glide slope), and preflare maneuvers would be performed by the autopilot, at which time the commander would take control and complete the landing.&lt;/p&gt;&#xA;&lt;p&gt;The result was one of the worst landings in the history of the program. The autopilot was unable to maintain a stabilized airspeed, at first closing the speedbrake completely, then opening it again until airspeed was low, then closing again at 4000 feet which caused the orbiter to be too fast by the time commander Jack Lousma took over. He didn't really have enough time to get a feel for the aircraft or make corrections, so it hit hard and fast.&lt;/p&gt;&#xA;&lt;p&gt;Afterwards, it was decided to discontinue testing of the autoland system, although the implementation was eventually completed.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Development of an automatic approach and landing system was terminated indefinitely due to the inability to implement an FAA [Federal Aviation Administration]-like powered aircraft certification program for an unpowered glider like the Space Shuttle. That is, an automatic system cannot be reasonably certified for an aircraft without a go-around capability in the event of an autoland system failure, because the only recourse in the Shuttle is to land rather than to execute a wave-off maneuver as in a powered aircraft. The practice of having to salvage a good landing out of a poor approach is not professionally accepted airmanship.&lt;/p&gt;&#xA;&lt;p&gt;Further, the STS-3 experience was classified as a “late-takeover” action in which a failure of the autoland system in even closer proximity to touchdown could result in an upset too late in the landing phase to be reasonably recoverable. &amp;quot;Monitoring&amp;quot; the approach versus actually &amp;quot;controlling&amp;quot; it induces a time lapse in the mental-to-physical control conversion process which increases in criticality for manual takeover as the aircraft approaches touchdown. An automatic failure on the IGS, with no recourse for a wave-off, would be unsafe compared to a totally manual- controlled approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The quote is from &lt;a href=&quot;http://www.jsc.nasa.gov/history/oral_histories/LousmaJR/LousmaJR_3-15-10.htm&quot; rel=&quot;noreferrer&quot;&gt;NASA Johnson Space Center Oral History Project&lt;/a&gt; where Jack Lousma gives a great description of the flight and landing a little less than half way down the page.&lt;/p&gt;&#xA;&lt;p&gt;The Columbia Accident Investigation Board Report did recommend testing the autoland system, but to my knowledge, it never was.&lt;/p&gt;&#xA;&lt;p&gt;Just to clarify, the autopilot &lt;em&gt;was&lt;/em&gt; used for most of reentry on every flight, but I believe your question was specifically about the final stages of flight and landing.&lt;/p&gt;&#xA;&lt;h1&gt;2. What sort of simulator was used for training?&lt;/h1&gt;&#xA;&lt;p&gt;So the shuttle was hand-flown for landing (a fly-by-wire system, so it's arguable that there's no true manual mode), and that means pilots have to be trained.&lt;/p&gt;&#xA;&lt;p&gt;They were actually trained in several different simulators. There was &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Avionics_Integration_Laboratory&quot; rel=&quot;noreferrer&quot;&gt;SAIL&lt;/a&gt; (Shuttle Avionics Integration Lab) where they did serious integrated systems and software testing.&lt;/p&gt;&#xA;&lt;p&gt;There were also fixed and motion-based simulators in Houston. These were collectively referred to as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Mission_Simulator&quot; rel=&quot;noreferrer&quot;&gt;SMS&lt;/a&gt; (Shuttle Mission Simulator). These were used for training for all phases of shuttle flights, not just landing. They were particularly useful for simulating contingencies, like an RTLS abort (return to launch site). It's similar to how simulators are used in the aviation industry to train for scenarios which would be too dangerous to train for in a real aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UQX6O.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UQX6O.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;The motion-base SMS. &lt;a href=&quot;https://www.facebook.com/The.Shuttle.Mission.Simulator/photos/a.452996032496.245533.358386467496/358398652496/?type=3&amp;amp;theater&quot; rel=&quot;noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;For nominal conditions, the best simulator for landing the space shuttle was actually another aircraft referred to as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Shuttle_Training_Aircraft&quot; rel=&quot;noreferrer&quot;&gt;STA&lt;/a&gt; (shuttle training aircraft). This was a modified Gulfstream II which would fly with its main landing gear lowered and thrust-reversers engaged to simulate the high drag profile of the orbiter. The left side of the STA cockpit was built to mimic the layout of the shuttle, including the heads up display.&lt;/p&gt;&#xA;&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/9/99/Gulfstream_II_Shuttle_Training_Aircraft.jpg&quot; alt=&quot;&quot; /&gt;&lt;br /&gt;&#xA;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/7/77/Shuttle_Landing_Simulator_cockpit.jpg&quot; alt=&quot;&quot; /&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Images from the STA's Wikipedia page&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The STA was used for both training shuttle pilots and for evaluating weather conditions at landing sites on launch and landing days.&lt;/p&gt;&#xA;&lt;p&gt;Lastly, there was also an on-orbit simulator that the pilots would use for practicing in the day or two before landing. It was basically a laptop with special flight-simulator software.&lt;/p&gt;&#xA;&lt;h1&gt;3. Is the simulator available in any flight simulators?&lt;/h1&gt;&#xA;&lt;p&gt;The answer depends on exactly what it is that you're asking. The actual software used on shuttle computers (written in &lt;a href=&quot;https://en.wikipedia.org/wiki/HAL/S&quot; rel=&quot;noreferrer&quot;&gt;HAL/S&lt;/a&gt;) is &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Traffic_in_Arms_Regulations&quot; rel=&quot;noreferrer&quot;&gt;ITAR&lt;/a&gt; restricted, so it is not available to the public. Sadly, even the on-orbit simulator has never been released, to my knowledge.&lt;/p&gt;&#xA;&lt;p&gt;However, there are several simulators which let you fly some or all of reentry and landing to varying degrees of realism.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.space-shuttle-mission.com/&quot; rel=&quot;noreferrer&quot;&gt;SSMS 2007&lt;/a&gt; is a pretty high-fidelity simulator, but has a &lt;em&gt;horrible&lt;/em&gt;, not even remotely accurate, reentry and landing.&lt;/li&gt;&#xA;&lt;li&gt;On phones and tablets, I love &lt;a href=&quot;http://www.f-sim.com/&quot; rel=&quot;noreferrer&quot;&gt;fsim Space Shuttle&lt;/a&gt;. It's decently realistic, but only lets you fly the subsonic portion of flight.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://orbit.medphys.ucl.ac.uk/&quot; rel=&quot;noreferrer&quot;&gt;Orbiter&lt;/a&gt;, which isn't a shuttle-specific simulator, but there are shuttle plugins. I've flown several manual reentries in Orbiter, but you really have to know what you're doing or you won't make the runway. That's probably the best option if you're really interested in orbital mechanics, and a terrible option if you're not.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.x-plane.com/desktop/home/&quot; rel=&quot;noreferrer&quot;&gt;X-Plane&lt;/a&gt; has a Space Shuttle scenario, but it's not particularly realistic.&lt;/li&gt;&#xA;&lt;li&gt;I know some people fly Shuttle missions on &lt;a href=&quot;https://kerbalspaceprogram.com/en/&quot; rel=&quot;noreferrer&quot;&gt;Kerbal Space Program&lt;/a&gt;, but I've never played with it at all so I can speak to it one way or the other.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Interestingly, the motion-based simulator from the SMS was donated to the Aerospace engineering department of Texas A&amp;amp;M, and it was discussed making the simulator at least partially available to the public. Unfortunately, I think they ran out of money to actually put the thing together and run it, so it's effectively just sitting in boxes in a room somewhere. They have a &lt;a href=&quot;https://www.facebook.com/The.Shuttle.Mission.Simulator/&quot; rel=&quot;noreferrer&quot;&gt;facebook page&lt;/a&gt;, but it's been a long time since I've seen any progress.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-29T10:11:15.443" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23995" PostTypeId="2" ParentId="23970" CreationDate="2015-12-29T10:41:16.770" Score="16" Body="&lt;p&gt;Fjords are also a reason these short routes exist, e.g. the trip from KKN to VDS takes less than 10 minutes, vs. driving 165 km (2h 16min according to Google: &lt;a href=&quot;https://goo.gl/ev5dya&quot; rel=&quot;noreferrer&quot;&gt;https://goo.gl/ev5dya&lt;/a&gt;)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/cnSZg.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cnSZg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12817" LastActivityDate="2015-12-29T10:41:16.770" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="23996" PostTypeId="1" AcceptedAnswerId="24014" CreationDate="2015-12-29T13:25:01.217" Score="2" ViewCount="507" Body="&lt;p&gt;I am simulating wind tunnel tests for a NACA64210 airfoil with the following conditions: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$P_\infty=101300$ $Pa$ ; $\rho = 1.23$ $kg/m^3$ ; $U_\infty = 29.99$ $m/s$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I performed the simulation with Solidworks Flow Simulation, and I obtained the following plots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N2cBt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N2cBt.png&quot; alt=&quot;Pressure Plot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K4P15.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K4P15.png&quot; alt=&quot;Velocity Plot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is about if these plots make sense and can be correct. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, I am wondering why in the velocity plot, the velocity is not zero at the leading edge (provided it should be a stagnation point), maybe it's because the wind tunnel speed is low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, as far as I know, the pressure distribution in a wing should be smaller in the upper side of the wing than in the lower to successfully create lift, in this case it seems to be equal at both surfaces. Also, there's usually a suction closer to the leading edge that I cannot detect here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I just need a review of my plots to know if they are correct or not, and if they are not correct what might be the cause of it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P.S:&lt;/strong&gt; The only setting that I was not sure about what to input, was that I enabled that the air was laminar and turbulent. I'm not sure if I should have stated only laminar, instead.&lt;/p&gt;&#xA;" OwnerUserId="4358" LastEditorUserId="19" LastEditDate="2017-01-25T14:22:55.860" LastActivityDate="2017-01-25T14:22:55.860" Title="Are these pressure and velocity distributions calculated by CFD simulation correct?" Tags="&lt;aerodynamics&gt;&lt;wind-tunnel&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="23997" PostTypeId="1" AcceptedAnswerId="24019" CreationDate="2015-12-29T14:13:34.603" Score="6" ViewCount="4694" Body="&lt;p&gt;Reading about &lt;a href=&quot;https://en.wikipedia.org/wiki/Helios_Airways_Flight_522&quot; rel=&quot;nofollow&quot;&gt;Helios Flight 552&lt;/a&gt; it is clear that the pressurization switch on a B737 has two modes: AUTOMATIC and MANUAL&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since it appears that one of the causes of the accident was an incorrect setting of the switch to MANUAL and due to hypoxia the first officer didn't spot the problem, why is it that a MANUAL setting is offered if it can lead to such disasters?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the use of the MANUAL position of the switch if the setting has to be set to AUTO for the flight?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2015-12-30T06:52:04.347" LastActivityDate="2015-12-30T06:52:04.347" Title="Why does the cabin pressurisation switch have a manual mode?" Tags="&lt;accidents&gt;&lt;boeing-737&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="23998" PostTypeId="1" CreationDate="2015-12-29T14:26:54.540" Score="0" ViewCount="48" Body="&lt;p&gt;What could one expect to be the most common cockpit system and reliant indicators to fail in a small airplane like a Cessna 172 or Piper Archer? Would gyroscope failures or vacuum pump failures be one?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: This question is different than this one: &lt;a href=&quot;https://aviation.stackexchange.com/questions/22114/what-component-of-an-aircraft-is-most-likely-to-fail&quot;&gt;What component of an aircraft is most likely to fail?&lt;/a&gt; because I am not asking about components, I am asking about systems and instruments.&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2015-12-31T03:49:08.997" Title="What are the most common cockpit system and instrument failures in small airplanes?" Tags="&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2015-12-29T15:55:03.840" ContentLicense="CC BY-SA 3.0" />
  <row Id="23999" PostTypeId="1" AcceptedAnswerId="24003" CreationDate="2015-12-29T14:52:46.727" Score="14" ViewCount="10090" Body="&lt;p&gt;According to my research, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Pulsejet&quot; rel=&quot;noreferrer&quot;&gt;pulsejet's&lt;/a&gt; thrust grows as the airspeed increases. Most pulsejets require no moving parts which makes it easier to manufacture them. They are also very lightweight which can have some great effects on aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are very slow at zero airspeed but very fast at high airspeeds. Therefore you could simply have a normal jet engine to power the take off and then switch after take off to the pulsejets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example where I've labelled a DC-10 of what a pulsejet with jet engine plane could look like:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/veYpm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/veYpm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane would taxi onto the runway using the jet engine as power, it'd then line up on the runway. It'd then power its jet engine and take off. Shortly after take off it would switch to the pulse engines and optionally turn the jet engine off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why don't planes use pulsejets? Surely they would allow planes to go faster and in turn allow them to reach destinations quicker. Also the pulsejets are easier and cheaper to produce than jet engines and there lighter than jet engines.&lt;/p&gt;&#xA;" OwnerUserId="12062" LastEditorUserId="22726" LastEditDate="2019-11-12T04:05:25.140" LastActivityDate="2020-09-10T21:20:36.287" Title="Why don't planes use pulsejets?" Tags="&lt;aircraft-design&gt;&lt;pulsejet&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24000" PostTypeId="1" AcceptedAnswerId="24001" CreationDate="2015-12-29T14:55:58.973" Score="5" ViewCount="30626" Body="&lt;p&gt;If you look at image 5-18 in the PHAK Chapter 5 about leading edge lift devices you see this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3peiu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3peiu.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the paragraph preceding it states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;High-lift devices also can be applied to the leading edge of&#xA;  the airfoil. The most common types are fixed slots, movable&#xA;  slats, leading edge flaps, and cuffs. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So is this a typo? Should the image say 'movable slat' instead of 'movable slot'? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This leads into my main question which is, what are the differences between a slat and a slot? If I were to get asked this by an examiner what would a good response be?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2015-12-29T15:18:36.820" Title="What are the differences between a slot and a slat?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24001" PostTypeId="2" ParentId="24000" CreationDate="2015-12-29T15:18:36.820" Score="6" Body="&lt;p&gt;I guess it should be movable slat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A leading edge slot is basically a spanwise opening in the wing. Slats are aerodynamic surfaces in the leading edge, which when deployed, allows the wing to operate at higher angle of attack. When deployed, the slat opens up a slot between itself and the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AhAuk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AhAuk.jpg&quot; alt=&quot;Slat-slot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from simhq.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft, the slats are fixed, which opens up a slot between the wing and the slat. In this case, the terms slot and slat are used interchangeably.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jgXBi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jgXBi.jpg&quot; alt=&quot;STOL slat&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Leading_edge_slot.jpg#/media/File:Leading_edge_slot.jpg&quot; rel=&quot;noreferrer&quot;&gt;Leading edge slot&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Sanchom&quot; rel=&quot;noreferrer&quot; title=&quot;User:Sanchom&quot;&gt;Sanchom&lt;/a&gt; - Own work. Licensed under CC BY 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of airliners use movable slats, in which case, the system is called slat, rather than slot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/92lAF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/92lAF.jpg&quot; alt=&quot;A319 slats&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Voilure_A319.jpg#/media/File:Voilure_A319.jpg&quot; rel=&quot;noreferrer&quot;&gt;Voilure A319&lt;/a&gt;&quot; by Nicourse - Own work. Licensed under CC BY-SA 3.0 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, the system is pretty much the same, but is (usually) called slat in case of movable one and slot in case of fixed one.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-29T15:18:36.820" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24002" PostTypeId="2" ParentId="14509" CreationDate="2015-12-29T15:19:25.743" Score="4" Body="&lt;p&gt;Efficiency is an energy thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Energy is force times distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Differentiate, you get power is force times speed. It turns out you don't even need to know the cruise thrust, you can calculate the efficiency on the TSFC (which is pretty much why it is used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although Concorde's engine were generating less force per unit flow, the vehicle was going 2.5 times further each second. If you divide the useful power (thrust times speed) into the power in the fuel (fuel flow times energy per unit mass of fuel) you can calculate the energy efficiency of Concorde's engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let's do that. Here's the basic numbers I found on the web, and I convert them into SI base units:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise speed = 2,124 km/h = 590m/s&#xA;TSFC @ cruise = 33.8 g/(kN·s) = 33.8e-6 kg/N.s&#xA;Specific energy of aviation fuel = 43.15 MJ/kg&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Energy per N m/s = power per Newton = force times speed per Newton = 590 m/s/Newton = 590 Joules per second per Newton&#xA;Fuel energy used by engine per N s = 43.15e6 MJ/kg x 33e-6 kg/N.s = 1458 joules per second per Newton&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So dividing one by the other, Newtons cancel and we get 40% efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bearing in mind that's in an aircraft, which is made as light as possible, for any aircraft, that's amazingly good; better than most electric generating power plants which are bolted to the ground, but some diesel engines can reach over 50% in very, very large ships, and you might exceed that in cars with cast-iron engines which would be far too heavy to be flown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's take a 747-400 at long range cruise with a CF6 engine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise speed 907km/h = 251 m/s&#xA;TSFC 17.1 g/(kN·s) = 17e-6 kg/N.s&#xA;So it's generating 251 J/s.N&#xA;and burning 17e-6 x 43.15e6J/kg = 733 J/s&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I make that 34% engine efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's it beating a high bypass turbofan that's used for long distance subsonic cruise. So it's not just that these engines were good for the time; they're still world-class.&lt;/p&gt;&#xA;" OwnerUserId="12819" LastActivityDate="2015-12-29T15:19:25.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24003" PostTypeId="2" ParentId="23999" CreationDate="2015-12-29T15:31:59.483" Score="40" Body="&lt;p&gt;2 reasons really:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Airplanes need most of their thrust right when their airspeed is low. (to get more airspeed at takeoff and go-around). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The maximum airspeed in cruise is not dictated by how much thrust the engines can throw out. Instead it's dictated by the aerodynamic forces on the airframe. They cruise right below the speed of sound where the rules of aerodynamics change drastically. Going too fast would rip an airplane apart.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2015-12-29T21:29:15.237" LastActivityDate="2015-12-29T21:29:15.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24004" PostTypeId="1" CreationDate="2015-12-29T15:44:06.147" Score="3" ViewCount="2764" Body="&lt;p&gt;During the pre flight inspection, usually the copilot checks many parts of the aircraft. Which are the parts and Why do they check them?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2015-12-29T23:24:01.047" Title="Before a flight, what are the most important things to check in an aircraft (walkaround)?" Tags="&lt;preflight&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24006" PostTypeId="2" ParentId="23999" CreationDate="2015-12-29T15:53:54.417" Score="16" Body="&lt;p&gt;There are multiple reasons for pulsejets not being used in aircraft (or manned aircraft generally).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;They are quite loud. In fact most of the pulsejet aircraft are (in)famous for their noise. One of the reasons for the US Army to reject the pulsejet powered XH-26 was the unacceptable noise.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/q8x3c.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/q8x3c.jpg&quot; alt=&quot;XH-26&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:XH-26_Jet_Jeep_in_flight.jpg#/media/File:XH-26_Jet_Jeep_in_flight.jpg&quot; rel=&quot;noreferrer&quot;&gt;XH-26 Jet Jeep in flight&lt;/a&gt;&quot; by San Diego Air &amp;amp; Space Museum Archives - &lt;a href=&quot;http://www.flickr.com/photos/sdasmarchives/4561399305/in/photostream/&quot; rel=&quot;noreferrer&quot;&gt;http://www.flickr.com/photos/sdasmarchives/4561399305/in/photostream/&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The intermittent (combustion) operation means that vibration is a serious problem. For aircraft engines this causes serious problem; especially for commercial airlines, such vibration levels would be unacceptable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Though pulsejets &lt;em&gt;can&lt;/em&gt; be operated in low (and even zero) airspeeds, it uses the dynamic pressure of air for compression. Hence the engine will be producing little thrust in the most critical phases of operation (takeoff and climb).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Pulsejets' combustion chamber operates at high temperature and requires heat resistant materials. Air cooling can improve this, but will complicate the engine.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are other things here- having a dead engine (assuming that the turbofan is turned off at some point) simply increases drag and weight penalty.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-29T15:53:54.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24007" PostTypeId="2" ParentId="23999" CreationDate="2015-12-29T16:11:33.087" Score="17" Body="&lt;p&gt;In your proposed design an engine failure at low speed would result in essentially no thrust.  So, additionally you would need to carry a second gas turbine engine for redundancy.&#xA;Then, during cruise you would be carrying around these two extra engines that are not being used, so they are just dead weight.  Overall, airliner engine selection is driven largely by fuel efficiency.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Pulsejet&quot;&gt;Wikipedia reports&lt;/a&gt; that pulse jets have poor specific fuel consumption.&lt;br&gt;&#xA;Also, pulse jets tend to be very loud, which can be a noise problem.  &lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2015-12-29T16:11:33.087" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24008" PostTypeId="2" ParentId="24004" CreationDate="2015-12-29T16:31:08.857" Score="2" Body="&lt;p&gt;The following is an (incomplete) list of checks carried out:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine - for any damage to blade (due to birdstrike etc.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tires - For any damage&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Oil level indicator&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Wings- Leading and trailing edges and tips for any damage&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Any oil leaks&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;APU&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rear fuselage- tail skid area&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine and fuselage- Any open cowling, exterior damage etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Probes- Any damage, ice etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Any other suspected damage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of helicopters, condition of rotors for any damage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A more detailed list can be seen elsewhere for &lt;a href=&quot;http://www.b737.org.uk/walkaround.htm&quot; rel=&quot;nofollow&quot;&gt;B737&lt;/a&gt; and &lt;a href=&quot;http://www.equicom.net/mcdu/blog20150714.php&quot; rel=&quot;nofollow&quot;&gt;A320&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-29T16:31:08.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24009" PostTypeId="1" AcceptedAnswerId="24011" CreationDate="2015-12-29T16:53:36.397" Score="0" ViewCount="1435" Body="&lt;p&gt;I'd like to have explanations of these landing descriptors - what do they mean?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;deep landing&lt;/li&gt;&#xA;&lt;li&gt;bounced landing&lt;/li&gt;&#xA;&lt;li&gt;hard landing&lt;/li&gt;&#xA;&lt;li&gt;nose pointed down landing&lt;/li&gt;&#xA;&lt;li&gt;technical landing&lt;/li&gt;&#xA;&lt;li&gt;&quot;smooth&quot; landing &lt;/li&gt;&#xA;&lt;li&gt;belly landing&lt;/li&gt;&#xA;&lt;li&gt;landing gear up landing&lt;/li&gt;&#xA;&lt;li&gt;partial landing gear up landing&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="6886" LastEditDate="2015-12-29T19:01:39.130" LastActivityDate="2015-12-29T19:01:39.130" Title="There are some types of landings, can you, please, clarify them? Or even add some other types" Tags="&lt;landing&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2015-12-29T19:44:36.510" ContentLicense="CC BY-SA 3.0" />
  <row Id="24010" PostTypeId="1" AcceptedAnswerId="24017" CreationDate="2015-12-29T17:46:10.027" Score="7" ViewCount="4833" Body="&lt;p&gt;Which supersonic (fighter) airplanes use the simple Pitot Air Intakes / Normal Shock Inlets?&lt;br&gt;&#xA;Two examples already seen here on Aviation.SE (&lt;a href=&quot;https://aviation.stackexchange.com/q/23840/12485&quot;&gt;one&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/a/9222/12485&quot;&gt;two&lt;/a&gt;) are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.dassault-aviation.com/en/defense/rafale/introduction/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dassasult Rafale&lt;/a&gt; ($Ma \leq 1.8$)&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/tjWeT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tjWeT.jpg&quot; alt=&quot;Dassault Rafale&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://www.airliners.net/photo/France---Air/Dassault-Rafale-C/2754292/M/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;General Dynamics / &lt;a href=&quot;http://www.lockheedmartin.com/us/products/f16.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed Martin F-16&lt;/a&gt; C/D Block 30/32 Fighting Falcon ($Ma \leq 2.0$)&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2AvGe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2AvGe.jpg&quot; alt=&quot;Lockheed Martin F-16 Fighting Falcon&quot;&gt;&lt;/a&gt;&#xA;&lt;em&gt;&lt;a href=&quot;http://www.airliners.net/photo/Turkey---Air/General-Dynamics-(TUSAS)/2734605/M/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there any more examples?&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="1467" LastEditorDisplayName="user12485" LastEditDate="2017-12-05T13:04:12.170" LastActivityDate="2017-12-05T13:04:12.170" Title="Which supersonic airplanes use Pitot Air intakes?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;fighter&gt;&lt;inlet&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24011" PostTypeId="2" ParentId="24009" CreationDate="2015-12-29T18:01:44.690" Score="3" Body="&lt;p&gt;From European Action Plan for the Prevention of Runway Excursions 1.0, &lt;a href=&quot;http://skybrary.aero/bookshelf/books/2065.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Appendix E- Aircraft Operators&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Deep landing – a certain distance behind the glide slope touchdown point&lt;/p&gt;&#xA;&lt;p&gt;Short landing – touching down before the glide slope touchdown point&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Belly landing&lt;/strong&gt; (or pancake landing or gear-up landing)-  The aircraft lands without its landing gear fully extended and uses its underside, or belly, as its primary landing device.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/po3Dd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/po3Dd.jpg&quot; alt=&quot;Belly landing&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Thunderbolt_II_080325.jpg#/media/File:Thunderbolt_II_080325.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thunderbolt II 080325&lt;/a&gt;&amp;quot; by U.S. Air Force photo/Brad White - Official USAF Website &lt;a href=&quot;https://i.stack.imgur.com/po3Dd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;1&lt;/a&gt;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Partial gear up landing&lt;/strong&gt;- One/or more of the landing gears fail to extend. Similar to belly landing, but in that case, all the gears fail usually.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Hard Landing&lt;/strong&gt;- The aircraft impacts the ground with a greater vertical speed and force than in a normal landing. The actual speed varies from aircraft to aircraft. This kind of landing usually requires some inspection afterwards.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Nose pointed down landing&lt;/strong&gt;- Aircraft usually land at a positive attitude (i.e. with nose pointed up). However, in some cases (usually due to some problem), the landing can be carried out with nose pointed down. This is normally in violation of standard procedures.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Arrested landing&lt;/strong&gt;- Usually done in carriers; an arrester cable is used to bring the aircraft to stop.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vcBGH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vcBGH.jpg&quot; alt=&quot;F-18&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:FA-18_Trap.jpg#/media/File:FA-18_Trap.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;FA-18 Trap&lt;/a&gt;&amp;quot;. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Smooth landing&lt;/strong&gt;- If the landing has no problems like given above, it can be called a smooth landing. It is subjective though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-29T18:01:44.690" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24012" PostTypeId="2" ParentId="24004" CreationDate="2015-12-29T18:52:12.773" Score="2" Body="&lt;p&gt;The other answer gives what is checked, but doesn't really touch on the &quot;why&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a few examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Birgenair_Flight_301&quot; rel=&quot;nofollow&quot;&gt;Birgenair 301&lt;/a&gt; - Crashed shortly after take-off because it is believed a pitot tube was blocked by a wasps nest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroper%C3%BA_Flight_603&quot; rel=&quot;nofollow&quot;&gt;Aeroperu 603&lt;/a&gt; - Crashed shortly after take-off because some tape was covering the static ports left there because of maintenance work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ainonline.com/aviation-news/business-aviation/2015-09-09/ntsb-faults-pilot-compliance-gust-lock-giv-crash&quot; rel=&quot;nofollow&quot;&gt;Gulfstream IV&lt;/a&gt; - Crashed during take-off because the gust locks were not deactivated (Gulfstream had some role to play in this because the gust lock system is supposed to limit throttle movement but was not operating properly).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ack.net/071008Conwaycrash.html&quot; rel=&quot;nofollow&quot;&gt;Twin Otter&lt;/a&gt; crashed just after take-off because the control lock was still in place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.dailymail.co.uk/news/article-2749485/Medical-flight-got-wrong-fuel-crash.html&quot; rel=&quot;nofollow&quot;&gt;Medical Flight&lt;/a&gt; crashed after take-off when it was refueled with JET-A instead of 100LL. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, there is little you can do in the air when something goes really wrong, but there is a lot you can do on the ground to make sure that the aircraft is worthy to fly. Preflight inspection is one step to a successful flight and preflight doesn't just happen on the tarmac walking around the plane, there are also safety checks that happen inside the cockpit (like verifying the controls are free) and even more before you even see the plane (checking weather, routes, destination airports, NOTAMs, etc).&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-29T20:35:02.573" LastActivityDate="2015-12-29T20:35:02.573" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24013" PostTypeId="2" ParentId="24010" CreationDate="2015-12-29T19:02:33.830" Score="4" Body="&lt;p&gt;Almost all the jet aircraft in the dawn of jet aircraft used the pitot intakes, like the Gloster E.28/39, MiG-15 and F-86A Sabre.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This trend was followed by the second generation supersonic combat aircraft, a good example of which would be &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19&quot; rel=&quot;nofollow noreferrer&quot;&gt;MiG-19&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/S6GOl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S6GOl.jpg&quot; alt=&quot;MiG-19&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MiG-19_HuAF_2.jpg#/media/File:MiG-19_HuAF_2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;MiG-19 HuAF 2&lt;/a&gt;&quot; by Varga Attila - Own work. Licensed under  &quot;&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/3.0/&quot; rel=&quot;nofollow noreferrer&quot;&gt;CC BY-SA 3.0&lt;/a&gt;&quot; via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TF-102A, the trainer version of &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F-102_Delta_Dagger&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-102 Delta Dagger&lt;/a&gt; had pitot inlets mounted on the sides below, similar to the Rafale; the single seat version had a different pitot inlet (on the sides) though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xJNCs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xJNCs.jpg&quot; alt=&quot;TF-102A&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from 456fis.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-100 Super Sabre&lt;/a&gt; used a pitot inlet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yIW9I.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yIW9I.jpg&quot; alt=&quot;F 100&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:North_American_F-100D_Super_Sabre_USAF.jpg#/media/File:North_American_F-100D_Super_Sabre_USAF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;North American F-100D Super Sabre USAF&lt;/a&gt;&quot; by USAF - U.S. Air Force photo 021210-F-1234P-041 from the National Museum of the United States Air Force. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-18A Hornet also uses a similar intake. The Taiwanese &lt;a href=&quot;https://en.wikipedia.org/wiki/AIDC_F-CK-1_Ching-kuo&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-CK-1 Ching-Kuo&lt;/a&gt; also has pitot inlets; in fact, the aircraft looks like a cross between F-16 and Rafale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0zizm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0zizm.jpg&quot; alt=&quot;F-CK-1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Wikimedia Commons&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorDisplayName="user12485" LastEditDate="2015-12-30T09:54:46.830" LastActivityDate="2015-12-30T09:54:46.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24014" PostTypeId="2" ParentId="23996" CreationDate="2015-12-29T19:16:47.370" Score="2" Body="&lt;p&gt;Qualitatively they seem to be correct:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Highest pressure at stagnation point and maximal pressure in diagram close to total pressure:&#xA;$$101843.84\ Pa \approx P_{tot}= P_{\infty}+\frac{\rho}{2}\cdot U_\infty^2 =101853\ Pa$$&lt;/li&gt;&#xA;&lt;li&gt;Speed drop at stagnation point.&lt;/li&gt;&#xA;&lt;li&gt;The slight flow deflection downwards behind the airfoil shows that your airfoil is generating lift (I am assuming your free stream flow is in x-direction).&lt;/li&gt;&#xA;&lt;li&gt;Low pressure (dark blue) region above airfoil is bigger than below.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As @ROIMaison wrote the correct way to validate the results is looking at the aerodynamic coefficients and pressure ditribution $c_p$. In a quick search I found some &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=naca64210-il&quot; rel=&quot;nofollow&quot;&gt;polars&lt;/a&gt; calculated with xfoil you should be able to replicate. With xfoil you can calculate the pressure distribution too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are only interested in lift at small angles of attack laminar flow simulation should be enough. If you also want to calculate drag I would set turbulent air. To validate your setup (model, boundary conditions,...) for turbulent flow there is a great &lt;a href=&quot;http://turbmodels.larc.nasa.gov/index.html&quot; rel=&quot;nofollow&quot;&gt;NASA webpage&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8749" LastActivityDate="2015-12-29T19:16:47.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24015" PostTypeId="2" ParentId="577" CreationDate="2015-12-29T21:48:06.670" Score="1" Body="&lt;p&gt;It's a difficult skill to acquire.  Think of the cloud clearance requirements as a guideline.  Do your level best to comply with them but know that there is really no simple way to judge your true distance from a cloud.&lt;br&gt;&lt;br&gt;It's a see-and-avoid world for the VFR pilot.  The cloud clearance requirements are virtually impossible to enforce and the visibility mins are only slightly less difficult!  All the feds are asking for is for VFR pilot to remain reasonably far away from clouds given the regime in which the plane is operating.  Planes moving quickly require more distance from clouds in order to see-and-avoid other planes.&lt;br&gt;&lt;br&gt;In Class B and in G/day below 10k, just stay of of clouds.  You can't be deviating a mile out of the way for a cloud in Class B...you'd really screw up ATC's plan.  All the little and slow planes fly in Class G during the day and under 10,000'...so just stay clear of clouds.&lt;br&gt;&lt;br&gt;Above 10,000'?  Stay a mile away.  There are some fast planes up there and they need room to react to a possible collision.&lt;br&gt;&lt;br&gt;Everywhere else?  Three miles is sufficient.  Mooneys, Bonanzas, Lancair 320/360...they're pretty fast but really only need about half a mile to avoid a collision.&lt;br&gt;&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2015-12-29T23:54:08.077" LastActivityDate="2015-12-29T23:54:08.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24017" PostTypeId="2" ParentId="24010" CreationDate="2015-12-29T23:09:04.743" Score="8" Body="&lt;p&gt;A pitot intake will decelerate supersonic flow in one single, &lt;a href=&quot;https://aviation.stackexchange.com/questions/12001/what-causes-the-reduction-in-speed-across-the-shockwave/12003#12003&quot;&gt;straight shock&lt;/a&gt;, while a ramp or &lt;a href=&quot;https://en.wikipedia.org/wiki/Inlet_cone&quot; rel=&quot;nofollow noreferrer&quot;&gt;cone intake&lt;/a&gt; will do this in several oblique shocks. It takes its name from the pitot tube, which in turn is named after the French physicist &lt;a href=&quot;https://en.wikipedia.org/wiki/Henri_Pitot&quot; rel=&quot;nofollow noreferrer&quot;&gt;Henri Pitot&lt;/a&gt; who invented it to measure flow speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The objective of an air intake is to supply the engine with a uniform flow of air at approximately Mach 0.4 to 0.5. At higher flight speeds as much of the kinetic energy of the flow as possible must be turned into a pressure increase. Doing so efficiently reduces the work of the engine's compressor and increases mass flow, and consequently thrust. A pitot intake will have the lowest mass and complexity of all intake types and is the preferred choice as long as the pressure recovery can be performed efficiently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A shock is the only way to decelerate supersonic flow. While the flow speed tangential to the shock will not be changed, the normal speed component is reduced downstream of the shock, approximately to the inverse of the upstream Mach number. The bigger the jump, the higher the friction losses in the shock become, the air is heated instead of compressed and pressure recovery suffers. Generally, those losses are acceptable up to a maximum flight speed of Mach 1.6. The lower mass of the pitot intake will make it more attractive, while for higher speeds the deceleration has to happen over several oblique shocks which are triggered by a spike or a ramp ahead of the intake lip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, all supersonic jets which were designed to fly at less than Mach 1.6 use a pitot intake for mass and complexity reasons. This includes the smaller US jets (&lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-100&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_F-101_Voodoo&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-101&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F-102_Delta_Dagger&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-102&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F2Y_Sea_Dart&quot; rel=&quot;nofollow noreferrer&quot;&gt;F2Y&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Vought_F-8_Crusader&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-8&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16&lt;/a&gt;) and their counterparts in the Soviet Union (&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19&quot; rel=&quot;nofollow noreferrer&quot;&gt;MiG-19&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Yakovlev_Yak-27&quot; rel=&quot;nofollow noreferrer&quot;&gt;Yak-27&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Yakovlev_Yak-38&quot; rel=&quot;nofollow noreferrer&quot;&gt;Yak-38M&lt;/a&gt;), Sweden (&lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_32_Lansen&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 32&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_35_Draken&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 35&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_37_Viggen&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 37&lt;/a&gt;), France (&lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault-Breguet_Super_%C3%89tendard&quot; rel=&quot;nofollow noreferrer&quot;&gt;Super Étendard&lt;/a&gt;), Egypt (&lt;a href=&quot;https://en.wikipedia.org/wiki/Helwan_HA-300&quot; rel=&quot;nofollow noreferrer&quot;&gt;HA-300&lt;/a&gt;), Taiwan (&lt;a href=&quot;https://en.wikipedia.org/wiki/AIDC_F-CK-1_Ching-kuo&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ching-Kuo&lt;/a&gt;) or Korea (&lt;a href=&quot;https://en.wikipedia.org/wiki/KAI_T-50_Golden_Eagle&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-50&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jUl8c.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jUl8c.png&quot; alt=&quot;Pressure recovery measurements from the YF-16&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressure recovery measurements from the YF-16 (source: &quot;Fundamentals of Fighter Design&quot;, RAeS Lecture by Ray Whitford, Cranfield University). The loss in efficiency above Mach 1.2 (left; 1 on the y scale denotes full conversion of kinetic energy into pressure) is readily apparent. This is mitigated by the pre-compression from the forebody at increasing angle of attack (right). The result is higher efficiency just when it is needed most, namely in turning supersonic flight. The same trick is used by the Rafale, and the wing root does this pre-compression in case of the F/A-18 and the Ching Kuo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SJh0h.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SJh0h.png&quot; alt=&quot;Top view of the right XB-70 intake at Mach 3&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Top view of the right XB-70 intake at Mach 3 (source: &quot;Fundamentals of Fighter Design&quot;, RAeS Lecture by Ray Whitford, Cranfield University). At Mach 3, a single shock intake would be grossly inefficient. Now a cascade of ever steeper oblique shocks is needed, culminating in a last straight shock. A multitude of moving ramps is required to adjust the geometry for the actual Mach number, and the square geometry, which is required for this flexibility, makes the intake tube much heavier (it is a pressure vessel, after all!) than the round tube of a pitot intake.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2015-12-30T08:13:15.800" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24018" PostTypeId="2" ParentId="24004" CreationDate="2015-12-29T23:18:25.517" Score="3" Body="&lt;p&gt;Many things are checked on a walkaround. The pilot-in-command should do the walkaround, not the co-pilot. The main classes of items are as follows:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;structural integrity&lt;/strong&gt;; the aircraft must be sound and undamaged and ready to fly&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;sensors&lt;/strong&gt;; sensors such as antennas and gauges should be undamaged and not have anything blocking them or adhering to them&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;clean flight surfaces&lt;/strong&gt;; the control surfaces and flight surfaces must be smooth and clean; for example, the wings must not have ice on them&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;no leaks&lt;/strong&gt;; hydraulic fluid, oil, fuel, and other critical liquids should not be leaking out of the aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;chocks, control locks and covers removed&lt;/strong&gt;; all chocks, protective coverings and locks should be removed before flight and stowed&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;correct tire inflation&lt;/strong&gt;; wear on the tires should not be excessive and the tires should be inflated properly&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;fasteners present and correct&lt;/strong&gt;; all bolts, shims, nuts and other fasteners should be present, undamaged, and correctly installed&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;hatches and fairings secure&lt;/strong&gt;; removable inspection plates and any other small doors, fairings and cowlings should be in place and secure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;lights ok&lt;/strong&gt;; the lights on the aircraft should operate correctly and their lenses should have no cracks or other defects&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;blades ok&lt;/strong&gt;; the propeller or turbine blades (as the case may be) should be perfect with no cracks or chips&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overlooking any of these sorts of items can cause (and has caused) serious accidents or incidents in flight or during takeoff and landing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2015-12-29T23:24:01.047" LastActivityDate="2015-12-29T23:24:01.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24019" PostTypeId="2" ParentId="23997" CreationDate="2015-12-30T00:53:09.450" Score="9" Body="&lt;p&gt;The B737 Next Generation models (737-600, -700, -800, and -900) all use a digital cabin pressure controller, which has AUTO, ALTN, and Manual modes.  Older 737's may use this digital controller or an analog controller with Auto, Standby, Manual AC and Manual DC modes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g0SNU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g0SNU.jpg&quot; alt=&quot;Digital Pressurization Controller&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;From &lt;a href=&quot;http://www.myairlineflight.com/cabin_pressurization.html&quot; rel=&quot;noreferrer&quot;&gt;MyAirlineFlight.com&lt;/a&gt;, which also has a depiction of the older, analog panel.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the digital panel, the Auto mode selects between two digital controllers which swap every flight so that if #1 is primary (in control in the Auto mode) this flight, #2 will be primary next flight.  The ALTN mode makes the &quot;other&quot; controller primary, so that if the primary controller fails, the other one can be selected.  With both the digital and the analog controllers, the Manual mode gives the pilots direct control over the outflow valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several reasons that this control is sometimes desirable; none of them are particularly common.  First, if you need to perform a ground pressurization check, the pilot or mechanic uses the manual mode to close the outflow valve and allow the aircraft to pressurize on the ground.  It isn't common, but there are some checks that require it.  Second, the manual mode is used to verify that the outflow valve DOES open and close.  This used to be a check performed by the pilots, but (in large part due to the Helios accident mentioned), it is now a maintenance-only function for many operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, if the flight must be conducted unpressurized, the manual mode allows this -- open the outflow valve fully, and there is no pressure differential -- say if you had a damaged window that needs to not be pressurized while the aircraft is ferried to where the window can be replaced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fourth, in the case of an emergency evacuation, it may be necessary to quickly depressurize the aircraft, and the manual mode allows the crew to open the outflow valve with only DC (i.e. only battery) power available.  (The automatic modes need AC power to operate.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, if both digital controllers fail in flight, then the crew needs a way to control the pressurization, and the manual mode is used for this.  Getting to this point is quite rare, but it can happen.  Controlling the pressurization manually takes a lot of time &amp;amp; attention by the First Officer, so it isn't something that's practiced in the aircraft, and because the really big cues that you're doing it well or poorly come from what your ears feel, it isn't something that's done in the simulator either.  But there has to be a way to manually control the pressurization, so the Manual mode is it.  (Loss of all generators in flight could also put you in this position -- with no AC power the Automatic mode is unavailable.  Again, an extremely rare event.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the removal of the outflow valve check from the pilots' preflight, the switch is typically left in the AUTO position always, unless maintenance is doing their checks.  More than a few times, crews got distracted in the middle of the outflow valve check, left the switch in manual, and never got back to it.  The usual result was a Cabin Altitude Warning shortly after climbing above 10,000'; if the crew recognized their error, they could simply switch back to Auto and continue.  If they didn't realize that they'd done, they'd shortly get a call from the back asking why the masks had dropped, and that was &lt;strong&gt;&lt;em&gt;usually&lt;/em&gt;&lt;/strong&gt; the big clue that things had gone wrong &amp;amp; they needed to go back &amp;amp; land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One might wonder why the Manual mode is annunciated by a green light rather than an amber one -- the amber light would show up when checking the Master Caution.  That was a design decision by Boeing a few decades ago, and I don't have insight into their thinking there.  (Much like, why did they use the same horn for Takeoff Configuration Warning as for Cabin Altitude Warning... it evidently seemed like a reasonable idea at the time.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2015-12-30T01:10:59.007" LastActivityDate="2015-12-30T01:10:59.007" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24020" PostTypeId="1" CreationDate="2015-12-30T01:53:47.183" Score="14" ViewCount="10125" Body="&lt;p&gt;Why did the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_PB4Y-2_Privateer&quot;&gt;PB4Y&lt;/a&gt; patrol aircraft use a single fin while the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_B-24_Liberator&quot;&gt;B-24&lt;/a&gt; it was derived from used twin fins?  I have read that the twin fins were thought to be superior but this was realized to be false.  Why did engineers believe the twin fins to be superior and what caused them to reconsider?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="12220" LastEditDate="2015-12-30T02:15:15.583" LastActivityDate="2018-03-12T19:50:19.333" Title="What are the advantages of single vertical stabilizer over a twin set?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24021" PostTypeId="2" ParentId="24020" CreationDate="2015-12-30T02:16:02.220" Score="0" Body="&lt;p&gt;Well, the double vertical stabilizer is still in use in many airplanes like the F-22, F-35, F-15, A-10, and the A300 Super Transporters as well as many other airplanes. So, there is not much &quot;reconsideration&quot; in aircraft design on twin or single stabilizers. The reasons for choosing one over the other is survivability (some military aircraft) or structural requirements compared to simplicity.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-30T14:19:40.450" LastActivityDate="2015-12-30T14:19:40.450" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24023" PostTypeId="1" AcceptedAnswerId="24037" CreationDate="2015-12-30T02:35:09.867" Score="15" ViewCount="1892" Body="&lt;p&gt;In &lt;a href=&quot;http://www.king5.com/story/tech/science/aerospace/2015/12/29/plane-lands-taxiway-instead-runway-sea-tac-airport/78024684/&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; article, an airliner landed on a taxiway instead of a runway. What might be the reasons that a pilot can mistake a taxiway for a runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I mostly know the answer for this question, but I want to see what you guys can find out too as well as making a reference point for others.)&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2016-08-31T16:45:19.470" LastActivityDate="2017-07-11T14:30:58.410" Title="For what reasons might a taxiway be mistaken for a runway?" Tags="&lt;safety&gt;&lt;airport&gt;&lt;runways&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24024" PostTypeId="2" ParentId="5213" CreationDate="2015-12-30T04:19:01.507" Score="1" Body="&lt;p&gt;In World War 1 there were aircraft spark gap transmitters and the pilot could send messages in Morse code to receivers on the ground but he could not receive wireless (now called radio) signals. There was limited communication from ground to aircraft using the following three methods;&#xA;Ground Strips.&#xA;Lamp Signals.&#xA;Poppet Panels.&#xA;The pilot had to fly and watch for signals at the same time.&#xA;Ground strips were white sheets 3 metres by 300 mm (10 feet by 1 foot) or larger. They were laid out as patterns or letters with a letter for such messages as 'Your (wireless) signal is weak' or, 'Repeat last (wireless) message' or 'I am not receiving your signal'.&#xA;Lamp signals, used later in WW1, used 'Lucas' signalling lamps. The operator aimed the light beam at the pilot when he thought it would be visible to him and send the message in Morse Code.&#xA;The Poppet Panel was a canvas shutter arrangement fixed to the ground and was worked by pulling a cord which made a white patch visible from the air. When the cord was released the panel showed a black patch. By pulling and releasing the cord the operator could send Morse Code messages to the pilot who had to fly with one hand, look over the side and write down the letters with his other hand. It was a difficult task.    &lt;/p&gt;&#xA;" OwnerUserId="12829" LastActivityDate="2015-12-30T04:19:01.507" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24025" PostTypeId="2" ParentId="24020" CreationDate="2015-12-30T04:49:42.383" Score="3" Body="&lt;p&gt;The additional weight associated with control surface hardware like cables, hinges, a beefy horizontal, etc must be a consideration.  The added complexity related to maintenance of the system might be another.  On the other hand, battle damage that might completely obliterate a single vertical may only damage one of the two on a plane equipped with a pair of verticals.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="4474" LastEditDate="2015-12-31T03:48:28.383" LastActivityDate="2015-12-31T03:48:28.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24026" PostTypeId="2" ParentId="24020" CreationDate="2015-12-30T06:17:09.540" Score="19" Body="&lt;p&gt;Why did engineers believe the twin fins to be superior?&lt;/p&gt;&#xA;&lt;p&gt;There doesn't seem to be any single definitive reason for selecting the number of vertical fins on an aircraft design (except, obviously, for the twin-boom designs such as the Lockheed P-38 or Fairchild C-119).  I've seen all of the following cited by one authority or another as advantages of multiple vertical fins.  (Sorry, I didn't save or remember the sources.)&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduced hangar overhead requirement.  This is the most common reason for including total aircraft height in a purchase specification, and it is a sine qua non requirement for carrier deployment.&lt;/p&gt;&#xA;&lt;p&gt;Also I remember reading a magazine article that supplied this reason for the triple tail on the Lockheed Constellation.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduced cantilever stress at the root.  This may actually save weight over the single-fin design.  It may also help keep a tactical aircraft from disintegrating under the enormous stress of combat manoeuvres.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduced parasite drag.  The lower half of a vertical fin can be twice as thick as the upper half.  A twin tail design effectively omits the lower half and uses the upper half twice.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For multi-engine designs, operating the rudders in the engine slipstream affords improved rudder authority at low speed.  Pilots who taxi loaded bombers into takeoff position between other loaded bombers like lots and lots of rudder authority.&lt;/p&gt;&#xA;&lt;p&gt;Also I notice that practically all the big flying boats of the 1940's Flying Clipper era had multiple vertical fins.  Those craft had some tricky low-speed steering requirements — they not only had to make their way through a busy harbor, but usually docked and undocked without a tugboat.  I'm only guessing at the connection though.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A single vertical fin can be masked by the fuselage wake at high angles of attack.  You can see how this could be a problem for modern fighter aircraft, which look like flying tennis courts.  Traditional bomber designs with their broad wings and heavy aerodynamic loading can also generate quite a troublesome fuselage wake.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Improved position and field of fire for a tail gunner.  I don't see it myself but I've heard the claim so I'm including it here.&lt;/p&gt;&#xA;&lt;p&gt;I concede that the tail gunner slot in the Avro appears to benefit from the absence of bracing structure.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduced rudder-induced roll due to a shorter rudder offset moment.  Fast tactical military aircraft have short wings, and you don't want the rudder to extend further from the roll axis than the ailerons do.  On the other hand, the rudder doesn't need to go all the way to the top of the fin, does it.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Twin fins can be canted to reduce radar return.  They usually are, although I don't understand how the designers know where the hostile radar will be.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the A10, the vertical fins actually mask the hot engine exhaust over a large angular area.  Thus in order to aim a ground-to-air heat-seeker up the tailpipes of an A10 you have to be directly behind it.  Which means that a few seconds ago you were directly in front of it, so good luck with that.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="453" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-31T02:36:47.760" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24027" PostTypeId="2" ParentId="23970" CreationDate="2015-12-30T06:29:21.517" Score="4" Body="&lt;p&gt;One other rational for unusually short overland flights is that the short hop is a layover to connect two small airports to a larger one.  A few years ago it was possible to fly between Johnstown PA (JST) and Altoona PA (AOO); which are ~30 miles/60 minutes apart by road.  It wasn't because the airline expected significant amount of traffic between the two towns.  The main route was between Johnstown and Washington-Dulles Airport (IAD) which was flown 3(?) times a day; one of those flights stopped in Altoona with the primary intent of offering a connection from it to DC.  This stop was cancelled in 2014, and only the direct flight is still offered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both airports are very small rural locations and commercial traffic is partially funded with &lt;a href=&quot;https://en.wikipedia.org/wiki/Essential_Air_Service&quot; rel=&quot;nofollow&quot;&gt;Federal Subsidies&lt;/a&gt;, so simple economics aren't the only consideration in the route planning. &lt;/p&gt;&#xA;" OwnerUserId="1396" LastActivityDate="2015-12-30T06:29:21.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24028" PostTypeId="2" ParentId="23840" CreationDate="2015-12-30T08:27:28.313" Score="7" Body="&lt;p&gt;It is a pitot intake, and the round shape makes the intake tube lighter. It is a pressure vessel, after all, because the intake converts flow speed into pressure and slows the flow of air to the engines down to approximately half of the speed of sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placing the intake squarely at the side would make them less efficient (a classic example for this would be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Blackburn_Buccaneer&quot; rel=&quot;noreferrer&quot;&gt;Blackburn Buccaneer&lt;/a&gt;). The bulging fuselage above effects a pre-compression of the flow at supersonic speed, especially at higher angle of attack when thrust is needed most. To put them together under the fuselage (&lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;Eurofighter&lt;/a&gt; style) would cause interference in single-engine mode and would require a higher landing gear. The chosen shape is the best compromise for a lightweight and efficient intake for a two-engined aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2015-12-30T08:27:28.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24029" PostTypeId="2" ParentId="24020" CreationDate="2015-12-30T10:54:19.830" Score="15" Body="&lt;p&gt;The Consolidated B-24 Liberator was designed in something of a hurry. In fact, the Consolidated company had told the USAAF (who had asked them to produce B-17 under license) that they would have the aircraft ready in the same time it takes to adapt B-17 for production in the Consolidated plant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, the parts of design were 'borrowed' from other aircraft. The twin tails were taken from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_XP4Y_Corregidor&quot; rel=&quot;noreferrer&quot;&gt;Consolidated XP4Y Corregidor&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hrP4u.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hrP4u.jpg&quot; alt=&quot;XP4Y&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:XP4Y-1_in_flight.jpg#/media/File:XP4Y-1_in_flight.jpg&quot; rel=&quot;noreferrer&quot;&gt;XP4Y-1 in flight&lt;/a&gt;&quot; by Unknown&lt;a href=&quot;//www.wikidata.org/wiki/Q4233718&quot; rel=&quot;noreferrer&quot; title=&quot;wikidata:Q4233718&quot;&gt;&lt;/a&gt; - This image is available from the United States Commons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apparently, the B-24 (which was Consolidated Model 32) used parts straight off from the XPFY (which was Consolidated Model 31), with many parts in vertical fin starting with the 31 prefix of the XPFY. Reportedly, some parts used were from other Consolidated Models, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_PB2Y_Coronado&quot; rel=&quot;noreferrer&quot;&gt;PB2Y Coronado Flying boat&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_PBY_Catalina&quot; rel=&quot;noreferrer&quot;&gt;PBY Catalina&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vll8O.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vll8O.jpg&quot; alt=&quot;B-24&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from acepilots.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More B-24s were produced than any other heavy bomber but it had its own share of problems. After sometime in service, the USAAF determined that &lt;a href=&quot;http://www.joebaugher.com/usaf_bombers/b24_19.html&quot; rel=&quot;noreferrer&quot;&gt;the aircraft would have better stability if it had a single vertical tail&lt;/a&gt; and a production aircraft was modified (called XB-24K) for testing this. Tests showed the following improvements:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Enhanced lateral stability and improved handling characteristics.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The design was better able to cope up with two engines out on one side condition.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Increases in field of fire for the ball turret, waist guns and top and tail turrets.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The army was impressed enough that it recommended that single tail be used in all future aircraft, with the model number B-24N. The B-24N also included other improvements like the installation of spherical Emerson model 128 turret in the nose, modified (knife edge) windscreens etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/paz1X.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/paz1X.jpg&quot; alt=&quot;B-24N&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from edwards.af.mil&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An order for over 5000 B-24Ns were placed, which were canceled later (in May 1945) as the war drew to an end and only a handful of B-24N with single vertical tails were made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_PB4Y-2_Privateer&quot; rel=&quot;noreferrer&quot;&gt;PB4Y-2 Privateer&lt;/a&gt; was developed from the later models of B-24 and had the single vertical fin in its design as a result. Most of the PB4Y-2s were in fact, delivered after the WWII.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hOQg6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hOQg6.jpg&quot; alt=&quot;Privateer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:PB4Y-2_Privateer_VP-23_in_flight.jpg#/media/File:PB4Y-2_Privateer_VP-23_in_flight.jpg&quot; rel=&quot;noreferrer&quot;&gt;PB4Y-2 Privateer VP-23 in flight&lt;/a&gt;&quot; by USN - Dictionary of American Naval Aviation Squadrons Volume 2: The History of VP, VPB, VP(H) and VP(AM) Squadrons &lt;a href=&quot;https://i.stack.imgur.com/hrP4u.jpg&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt;; U.S. Navy National Museum of Naval Aviation photo No. 2011.003.156.015. Licensed under Public Domain via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2015-12-31T02:22:13.593" LastActivityDate="2015-12-31T02:22:13.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24030" PostTypeId="1" AcceptedAnswerId="24033" CreationDate="2015-12-30T11:05:20.417" Score="0" ViewCount="394" Body="&lt;p&gt;What was the total quantity issued of this model aircraft (including any modifications).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SfHNC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SfHNC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12833" LastEditorUserId="62" LastEditDate="2015-12-30T13:54:48.683" LastActivityDate="2015-12-30T13:54:48.683" Title="How many of this aircraft were manufactured?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24031" PostTypeId="2" ParentId="24023" CreationDate="2015-12-30T11:05:26.100" Score="6" Body="&lt;p&gt;As Air Traffic Controller, I can say that there are many reasons, but mostly:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Unfamiliar airports.&lt;/li&gt;&#xA;&lt;li&gt;Poor visibility during taxi in and taxi out.&lt;/li&gt;&#xA;&lt;li&gt;Low situational awareness.&lt;/li&gt;&#xA;&lt;li&gt;Poor signage on airside.&lt;/li&gt;&#xA;&lt;li&gt;Bad judgement from the crew.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="13197" LastEditDate="2016-04-26T22:17:46.473" LastActivityDate="2016-04-26T22:17:46.473" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24033" PostTypeId="2" ParentId="24030" CreationDate="2015-12-30T11:24:46.137" Score="2" Body="&lt;p&gt;The aircraft looks like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_CV-240_family&quot; rel=&quot;nofollow&quot;&gt;Convair CV 440 Metropolitan&lt;/a&gt; (maybe CV 340) a variant of the CV 240, in operation with the &lt;a href=&quot;https://en.wikipedia.org/wiki/KLM&quot; rel=&quot;nofollow&quot;&gt;KLM&lt;/a&gt;. According to Wikipedia, a total of 1181 of all the variants were built.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-30T11:24:46.137" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24034" PostTypeId="1" CreationDate="2015-12-30T12:17:11.270" Score="11" ViewCount="2325" Body="&lt;p&gt;Are there cases of airports where a large wingspan aircraft on a taxiway can interfere with another aircraft on the runway? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or do the airport design parameters take care that the largest wingspan aircraft on a taxiway will still never infringe on a runway's safety zone?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about taxiway-to-taxiway interference? Is that precluded by design itself for worst case combinations or can there be cases where two large wingspan aircraft on two taxiways may interfere?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, is it the pilot's duty primarily or the tower's  to ensure that interference does not occur due to conflicting wingspans of aircraft on different taxiways? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are taxiways with potential for such interference separately indicated on the airport taxi charts?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-07-07T10:14:46.203" LastActivityDate="2016-07-07T10:14:46.203" Title="What regulations or procedures address runway-taxiway interference for aircraft with large wingspan?" Tags="&lt;taxiing&gt;&lt;airport-design&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24035" PostTypeId="2" ParentId="24034" CreationDate="2015-12-30T13:00:23.060" Score="-2" Body="&lt;p&gt;Well, runway-taxiway interference would not exist because the airports are designed with enough buffer space in between to keep the aircraft separated. The only place that that might occur is when at least two of those aircraft land at an airport that is not designed for them (Like that would happen anyways).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxiway-taxiway interference is very similar to the one above, and only very rare occasions would have that occurring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basic answer then: No, it would not occur. However, if need be, the airport does issue warnings and prohibitions on what airplanes can use a certain taxiway like on the top right corner on the diagram of &lt;a href=&quot;http://flightaware.com/resources/airport/ATL/APD/AIRPORT+DIAGRAM/pdf&quot; rel=&quot;nofollow&quot;&gt;KATL Airport&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2015-12-30T13:06:36.510" LastActivityDate="2015-12-30T13:06:36.510" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24037" PostTypeId="2" ParentId="24023" CreationDate="2015-12-30T13:41:46.967" Score="18" Body="&lt;p&gt;Essentially, some taxiways look very like runways and they might even be more visible to pilots in certain conditions. That leads the pilots to focus on the taxiway rather than the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2007 the FAA &lt;a href=&quot;http://www.airtech.tc.faa.gov/safety/downloads/TN07-54.pdf&quot;&gt;commissioned a study&lt;/a&gt; into ways to avoid pilots landing on taxiways, with special emphasis on &lt;a href=&quot;http://www.airnav.com/airport/KSEA&quot;&gt;KSEA&lt;/a&gt; (Seattle-Tacoma). One of their goals was to address exactly the scenario in the article you linked to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Find a solution for the Seattle-Tacoma International Airport (SEA-TAC)&#xA;  problem by  identifying possible visual aid enhancements to prevent&#xA;  pilots from mistakenly  identifying taxiway Tango as the adjacent&#xA;  runway 16R as a landing surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The study mentions several reasons why pilots mistake taxiways for runways:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;A pilot will generally associate an air traffic control (ATC) instruction such as “cleared to land runway 16R,” with their visual presentation of the runway configuration&lt;/em&gt;. In other words, pilots see a taxiway where they expect to see a runway: this was a particular problem at KSEA because until the third runway was built, it had 16L and 16R, with taxiway T located to the right of 16R. Therefore a pilot landing on 16R would see three 'strips' with taxiway T as the rightmost one and might assume it was 16R. KSEA now has 3 runways with taxiway T between 16R and 16C.&lt;/li&gt;&#xA;&lt;li&gt;Some taxiways look physically very like runways, i.e width, surface material, square edges etc.&lt;/li&gt;&#xA;&lt;li&gt;Some taxiways stand out more clearly in low light conditions because their surface is lighter than the runways&lt;/li&gt;&#xA;&lt;li&gt;Sun glare can hide runway and taxiway markings so that pilots can't tell the difference visually&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's also an FAA &lt;a href=&quot;https://www.faa.gov/airports/engineering/engineering_briefs/media/EB-72a.pdf&quot;&gt;engineering brief&lt;/a&gt; that explains how to identify potential problem taxiways, it gives essentially the same information as the study.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both documents say that the most important point is to alert pilots in advance about the potential problem by giving warnings via ATIS, charts and so on. That's especially true for pilots who aren't familiar with the airport, and GA pilots make more mistakes than airline pilots so presumably training and general currency/professionalism as well as having at least 2 pilots in the cockpit makes a difference too.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2015-12-30T13:41:46.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24038" PostTypeId="2" ParentId="24034" CreationDate="2015-12-30T14:17:59.247" Score="12" Body="&lt;p&gt;Yes this can and &lt;a href=&quot;http://www.nbcnews.com/id/42548948/ns/travel-news/t/massive-jet-clips-spins-smaller-plane-jfk/#.VoPlCEorJhE&quot;&gt;has happened&lt;/a&gt; with what is considered a &quot;super-jumbo&quot; like the A380 or the 747-8 (Aircraft Design Group VI aircraft). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA must issue waivers to airports to legally accept these types of aircraft due to spacing rules that are in place. A lot of larger airports built quite a few years ago didn't have the foresight to handle aircraft of this size, so special precautions have to be taken when handling those types of aircraft. For class VI aircraft, an airport must have taxiways that are 100' wide and runways that are 200' wide. Note though that an A380's wingspan is 262', so even on a 100' taxiway, the wings hang over 81' on either side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually ground controllers get special training to handle the larger aircraft and maintain separation, but its even a problem for the ground crew before talking to ground control because there are quite a few notable incidents of aircraft being backed into other aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some interesting reads:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.miami-airport.com/pdfdoc/a380-presentation.pdf&quot;&gt;Miami International A380 Preparations&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://www.lawa.org/uploadedFiles/ONT/pdf/Appendix%206%20-%20A-380%20Operational%20Plan.pdf&quot;&gt;Los Angeles LAX A380 Operational Plan&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-30T19:19:41.047" LastActivityDate="2015-12-30T19:19:41.047" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24039" PostTypeId="2" ParentId="24034" CreationDate="2015-12-30T16:07:46.940" Score="7" Body="&lt;p&gt;Airport design standards try to to take into account the operation of airliners with large wingspan. Basically, the standards like the &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentNumber/150_5300-13&quot; rel=&quot;noreferrer&quot;&gt;FAA Advisory circular 50/5300-13A - Airport Design&lt;/a&gt; and &lt;a href=&quot;http://www.icao.int/safety/implementation/library/manual%20aerodrome%20stds.pdf&quot; rel=&quot;noreferrer&quot;&gt;ICAO Aerodrome design and operations&lt;/a&gt; require certain minimum separation distances between the runway/taxiways based on the wingspan of the aircraft being operated there.&lt;/p&gt;&#xA;&lt;p&gt;The aircrafts are separated into different groups based on their wingspan. For example, the following table is from the FAA AC 150/5300:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rQUc7.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rQUc7.png&quot; alt=&quot;ADG&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Table from FAA AC 150/5300-13 Airport Design.&lt;/p&gt;&#xA;&lt;p&gt;The ICAO definitions are more or less similar. Based on the most demanding dimension (like wingspan) of the aircraft expected to be operated in the airport, the  airport facilities can be determined. For example, the minimum recommended separation distances can be determined from the following table:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WvNno.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WvNno.png&quot; alt=&quot;Runway separation&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Table from FAA AC 150/5300-13 Airport Design.&lt;/p&gt;&#xA;&lt;p&gt;In case the airports with lesser separation distances (as is the case with many older airports) , the aircraft can still be operated if it is found that the separation doesn't affect the normal operations. From ICAO Aerodrome design manual:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Taxiway minimum separation distances&lt;/p&gt;&#xA;&lt;p&gt;3.8.7 The separation distance between the centre line of a taxiway and the centre line of a runway, the centre line of a parallel taxiway or an object shall not be less than the appropriate dimension specified in Table 3-1, except that it may be permissible to operate with lower separation distances at an existing aerodrome if an aeronautical study indicates that such lower separation distances would not adversely affect the safety or significantly affect the regularity of operations of aeroplanes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Another point to note is that the dimensions of aircraft also affect the airport aprons, building separation etc.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;One of the most important problems during the induction of A380 was that the aircraft, with a wingspan of ~262' is at the extreme end of the dimensions considered for airport design; in fact, the airport dimensions was an important design consideration in the A380. Still, it was expected that the A380 operation will be severely restricted because of its dimensions.&lt;/p&gt;&#xA;&lt;p&gt;To this end, the A380 Airport Compatibility Group (AACG) was formed to study the capabilities of airports to handle the superjumbo. It identified airports that can accommodate the A380 during normal operations, and those airports which were considered for planned alternates for A380 (in which case, the A380 is required not to disrupt the normal operations).&lt;/p&gt;&#xA;&lt;p&gt;The group found that the operations of A380 in runway/taxiway would affect other traffic due to the huge wingspan of A380. From the &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjTg6Ku-IPKAhWUUo4KHcHUDIcQFggiMAE&amp;amp;url=http%3A%2F%2Fwww.aci.aero%2Faci%2Faci%2Ffile%2FTechnical_Safety%2FA380%2520infrastruture%2520reqs%2520-%2520alternates.doc&amp;amp;usg=AFQjCNGXNxfjNn1x96AaRRVtY6Qf8VZ0qA&amp;amp;bvm=bv.110151844,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;draft document&lt;/a&gt;, which considered the ICAO standards:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;e) Taxiing of an A380 on a parallel taxiway, runway – taxiway separation is 107.5 meters,&lt;/p&gt;&#xA;&lt;p&gt;The A380 wingtip will infringe the runway strip with a distance of 7.5 meters. Operations on the runway should therefore temporarily be halted until the A380 has left the parallel taxiway.&lt;/p&gt;&#xA;&lt;p&gt;f) Taxiing of an A380 on a parallel taxiway, runway – taxiway separation is 182.5 meters,&lt;/p&gt;&#xA;&lt;p&gt;The A380 wingtip will infringe the runway strip with a distance of 7.5 meters1. Take-off operations can be operated as normal but instrument landings may temporarily be halted until the A380 has left the parallel taxiway. Non instrument landings however could be operated normally&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the end, this required the regulatory authorities to give waiver for operation of A380 in airports not meeting the spacing requirements. This is not unique for A380. Boeing also considered &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2010_q3/3/&quot; rel=&quot;noreferrer&quot;&gt;operations from existing airports for 747-8&lt;/a&gt; which has a larger wingspan compared to 747-400. The result is either a waiver or changing the operational procedure; Boeing notes:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;In some cases, airports can accommodate the airplane on the airport movement areas through the use of operational procedures. For example, when a 747-8 is taxiing, operations on a parallel taxiway that is built to less than the required separation standards may be limited to airplanes with a smaller wingspan in order to maintain adequate separation clearances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Basically, Boeing concludes that operating 747-8 is possible in all airports operating 747-400 (whose dimensions are used in planning separation distances in a number of airports) by getting a waiver after carrying out a study or a change in operating procedures.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Aircraft manufacturers are aware of the issues due to separation requirements as the wingspans get ever larger. For example, Boeing is offering an option of folding wingtips in the next version of 777.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2015-12-30T16:07:46.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24040" PostTypeId="1" AcceptedAnswerId="24044" CreationDate="2015-12-30T16:39:47.587" Score="9" ViewCount="1779" Body="&lt;p&gt;I do not understand when the Compass around a VOR is and is not present on maps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, around Kansas City:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://skyvector.com/?ll=38.84758946647894,-94.73760216321206&amp;amp;chart=112&amp;amp;zoom=3&amp;amp;fpl=undefined&quot;&gt;VOR OJC&lt;/a&gt; has been deactivated for quite some time now.  But its compass is still present on the latest map revision. (the frequency has hash-marks through it, indicating the deactivated status.&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why hasn't the map been updated to remove the compass?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://skyvector.com/?ll=39.12040037181039,-94.59659806218083&amp;amp;chart=112&amp;amp;zoom=3&amp;amp;fpl=undefined&quot;&gt;VOR RIS&lt;/a&gt; is still active, but does not have a compass around it.&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why isn't the compass on this active VOR?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any general guidelines for when a compass is present on the map?&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2015-12-30T16:46:41.747" LastActivityDate="2015-12-30T19:35:43.183" Title="When is a VOR shown on maps?" Tags="&lt;vor&gt;&lt;map&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24041" PostTypeId="2" ParentId="24040" CreationDate="2015-12-30T17:14:04.237" Score="1" Body="&lt;p&gt;In the case of OJC you can see that the frequency has hatching through it denoting that it has been shut down. However you also see a 77 that is not hatched out. This denotes the units &lt;a href=&quot;https://en.wikipedia.org/wiki/Tactical_air_navigation_system&quot; rel=&quot;nofollow&quot;&gt;TACAN channel&lt;/a&gt; (making it a VOR-TAC facility). Although TACAN is mainly a military technology some civilian aircraft are equipped with it. As such the VOR facility may have been shutdown but the TACAN equipment is still up and running thus the compass around it remains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For VOR RIS  the compass may not be present due to clutter. In some cases things are omitted from VFR maps to reduce clutter. You can find some &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=60628&quot; rel=&quot;nofollow&quot;&gt;discussion in this thread here&lt;/a&gt;. It seems that in some cases its up to the discretion of the cartographer. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2015-12-30T17:42:23.123" LastActivityDate="2015-12-30T17:42:23.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24042" PostTypeId="2" ParentId="24040" CreationDate="2015-12-30T17:51:53.397" Score="1" Body="&lt;p&gt;&lt;strong&gt;Why hasn't the map been updated to remove the [OJC] compass?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the FAA's &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;chart users guide&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NAVAIDS in a shutdown status have the frequency and channel  number&#xA;  crosshatched. Use of the NAVAID status “shutdown” is  only used when a&#xA;  facility has been decommissioned but cannot  be published as such&#xA;  because of pending airspace actions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course, that just changes the question to &quot;what are pending airspace actions&quot;? But the &lt;a href=&quot;http://aeronav.faa.gov/afd/10dec2015/nc_101_10DEC2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;A/FD entry for OJC&lt;/a&gt; says it isn't a VOR but rather a VOR/DME:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;(T) VORW/DME&lt;/strong&gt; 113.0   OJC   Chan 77   at Johnson Co Executive. 1034/6E. VOR dcmsnd: DME still operational&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the DME portion of the VOR/DME is still active, even if the VOR itself has been decommissioned (and as @Dave pointed out &lt;a href=&quot;https://aviation.stackexchange.com/a/24041/62&quot;&gt;in his answer&lt;/a&gt;, you can also see on the chart itself that the DME channel isn't crossed out). I had a quick look at some of the instrument procedures around there and couldn't immediately see where the DME is used, but presumably someone needs it for something, at least for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why isn't the compass on this active VOR?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most likely because the map is simply very cluttered at that point; &lt;a href=&quot;https://skyvector.com/?ll=40.82503181864719,-74.03807214492264&amp;amp;chart=301&amp;amp;zoom=1&amp;amp;fpl=undefined&quot; rel=&quot;nofollow noreferrer&quot;&gt;the TEB VOR/DME is another example&lt;/a&gt; where there's no rose on the VFR chart (although there is one on the TAC). The LGA and JFK roses already overlap there and adding TEB as well would be quite messy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found some discussions online that said a) only terminal VORs may not have a rose; and b) including the rose or not is the chart designer's decision. But there were no sources quoted for either statement.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2015-12-30T17:51:53.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24043" PostTypeId="2" ParentId="3548" CreationDate="2015-12-30T19:26:48.443" Score="1" Body="&lt;p&gt;Many people misread 14 CFR 91.146.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key is to start with (b) which does NOT impose limitations but rather says essentially that &quot;if a bunch of conditions are met&quot; then certain requirements of parts 119 and 120 do not apply.  In other words, IF certain conditions are met then a non-commercial pilot can do the equivalent of 91.147 operations under 91.146.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If, however, those conditions are NOT met, all that &quot;b&quot; means is that the pilot is not relieved from obligations under parts 119 and 120 [generally requiring a commercial pilot's certification and either an LOA for 91.147 or other certification for e.g. part 135 ops].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on whether compensation is provided in a non pro-rata way, the flight may be a private pilot flight as discussed above and subject only to the normal restrictions (common goal amongst all passengers, pro-rata expenses only) or if a commercial pilot is exercising an approved-LOA 91.147 operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IF, however, the pilot CHOOSES to meet the extra criteria of b1-b11 and follows (e) then compensation from the charitable event may be received just as it can during 91.147 operations -- and with similar flight restrictions (25sm, nonstop) only with higher pilot qualifications (500hrs) and operational restrictions (FSDO approval and limited number of times a year).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think of 91.146 as THE ONLY WAY a pilot not holding a commercial certificate can be paid more than the pro-rata share, do the equivalent of a 91.147 flight, but have to have a lot more hours and ops restrictions.&lt;/p&gt;&#xA;" OwnerUserId="12839" LastEditorDisplayName="user12485" LastEditDate="2015-12-30T21:01:39.327" LastActivityDate="2015-12-30T21:01:39.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24044" PostTypeId="2" ParentId="24040" CreationDate="2015-12-30T19:35:43.183" Score="5" Body="&lt;p&gt;See the &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/iacc/&quot; rel=&quot;noreferrer&quot;&gt;Interagency Air Cartographic Committee (IACC) Specifications&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/iacc/media/IACC2/IACC-2-26OCT2015-ch3.pdf&quot; rel=&quot;noreferrer&quot;&gt;[IACC 2]&lt;/a&gt;&lt;/em&gt;&lt;/strong&gt; &lt;strong&gt;3.9.3.8 Compass Roses&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Compass roses, as illustrated in Appendix 6, shall be shown centered on all VHF NAVAIDs, when space allows.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Preference shall be given to those serving enroute functions or located in areas not served by other VHF NAVAIDs.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/iacc/media/IACC5/IACC-5-27OCT2014-Ch3.pdf&quot; rel=&quot;noreferrer&quot;&gt;[IACC 5]&lt;/a&gt;&lt;/em&gt;&lt;/strong&gt; &lt;strong&gt;3.7.4.5 Compasses Roses&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Compass roses shall be charted centered on those NAVAIDs which have routes predicated on them. Compass roses may be shown around other NAVAIDs where placement of the compass rose does not create additional unnecessary clutter or congestion. If compass roses overlap and congestion hinders readability, the compass rose of the NAVAID with the most congestion may be deleted. Compass roses shall be shown oriented to slave magnetic North. Cardinal direction values shall not be shown. Compass roses shall be .75&quot; in diameter and in very congested areas may be reduced in size to .5&quot; in diameter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In groundschool I was taught that this is actually based on &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range#Service_volumes&quot; rel=&quot;noreferrer&quot;&gt;VOR service volumes&lt;/a&gt; (which otherwise aren't explicitly marked at all on VFR sectional charts): the compass rose is not shown around VORs with &lt;em&gt;Terminal&lt;/em&gt; service volumes. This might be a general rule, but it is not entirely true however. You provide a perfect example: OJC and RIS are both Terminal VORs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key differences: 1) OJC has the V10-12 airway, and 2) map is more congested around RIS.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2015-12-30T19:35:43.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24045" PostTypeId="1" AcceptedAnswerId="24046" CreationDate="2015-12-30T19:43:51.970" Score="9" ViewCount="6348" Body="&lt;p&gt;Does a PPL require a specific rating or endorsement for night VFR in the US? Night flying seems like a special challenge and I'd think the FAA would want you to show that you've had proper training for it. &lt;a href=&quot;https://aviation.stackexchange.com/q/3397/8730&quot;&gt;This question&lt;/a&gt; talks about currency requirements, but I can't find anything on a night VFR endorsement. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-04-25T19:55:14.163" Title="Does the FAA require a rating for night VFR?" Tags="&lt;faa-regulations&gt;&lt;night-flying&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24046" PostTypeId="2" ParentId="24045" CreationDate="2015-12-30T20:06:32.563" Score="11" Body="&lt;p&gt;There's no separate night rating or endorsement in the US, it's included in the private pilot flight proficiency requirements (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_1107&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.107&lt;/a&gt;) and the specific required experience is in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.2.61#se14.2.61_1109&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.109&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) Except as provided in §61.110 of this part, 3 hours of night&#xA;  flight training in a single-engine airplane that includes—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) One cross-country flight of over 100 nautical miles total&#xA;  distance; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) 10 takeoffs and 10 landings to a full stop (with each landing&#xA;  involving a flight in the traffic pattern) at an airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some very minimal instrument training is also required, which can be helpful at night:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) 3 hours of flight training in a single-engine airplane on the&#xA;  control and maneuvering of an airplane solely by reference to&#xA;  instruments, including straight and level flight, constant airspeed&#xA;  climbs and descents, turns to a heading, recovery from unusual flight&#xA;  attitudes, radio communications, and the use of navigation&#xA;  systems/facilities and radar services appropriate to instrument&#xA;  flight;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That all applies to private pilots; &lt;a href=&quot;https://www.faa.gov/licenses_certificates/airmen_certification/sport_pilot/&quot; rel=&quot;nofollow noreferrer&quot;&gt;sport pilots&lt;/a&gt; may not fly at night. And as David &lt;a href=&quot;https://aviation.stackexchange.com/questions/24045/does-the-faa-require-a-rating-for-night-vfr/24046?noredirect=1#comment66676_24046&quot;&gt;pointed out&lt;/a&gt;, there is an exception to the night requirements under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_1110&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.110&lt;/a&gt; for pilots in Alaska: they can skip the night training but if they do, they can't fly at night.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-25T19:55:14.163" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24047" PostTypeId="2" ParentId="24020" CreationDate="2015-12-30T21:00:36.467" Score="2" Body="&lt;p&gt;There are multiple reasons for twin vs single fins. In the world war 2 era, twin fins were used to help with engine out performance. The blue line speed on WW2 twins might be 50 mph faster than the take off speed, and even on four engine designs it was a major factor because bombers on take off were heavily loaded. Lose an engine and it would be a very close thing 4 engined or 2. Twin fins helped in this respect by lowering the blue line speed over single finned designs.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2015-12-30T21:00:36.467" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24048" PostTypeId="1" AcceptedAnswerId="24049" CreationDate="2015-12-31T03:19:20.070" Score="10" ViewCount="393" Body="&lt;p&gt;Is there any special consideration for the first flight as a captain? I mean, the first officer gets promoted to captain, does his/her first flight gets supervised by any special way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: I'm tagging this question as faa-regulation, not so sure if it is correct.. please correct me if I'm wrong&lt;/p&gt;&#xA;" OwnerUserId="12841" LastEditorUserId="19" LastEditDate="2016-06-27T07:52:59.723" LastActivityDate="2016-06-27T07:52:59.723" Title="What kind of supervision do new captains get on their first flight?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24049" PostTypeId="2" ParentId="24048" CreationDate="2015-12-31T03:36:30.470" Score="11" Body="&lt;p&gt;After a new captain is done with schoolhouse training (classroom and simulator) they will fly on-line as a captain and will have a training captain in the right seat.  After some number of flights (for me it was a 4-day pairing) you will be joined by a check airman in the jumpseat and have a line check. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you pass the line check if you are a first time captain you are a high minimums captain for your first 100 hours and then a normal captain. During high mins time you are subject to a few restrictions in approaches you can fly. All the flying after the line check is with normal (low time) first officers. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2015-12-31T03:36:30.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24050" PostTypeId="2" ParentId="23907" CreationDate="2015-12-31T04:02:39.823" Score="1" Body="&lt;p&gt;I flew a few times out of some very cold places... on video shoots (I work in film/video). Places like Albany NY, Buffalo, and Wyoming. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those airports are pre-pared to deal with the snow, so what would fully shut down an airport like say Austin; its business as usual in Albany. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being in a window seat, and watching a guy in a cherry picker with a fire hose outside your plane spraying down the entire aircraft with I assume a de-freezing chemical solution similar to whats in your windsheild wiper spray; was pretty scary the first time. It was snowing hard. Everything was covered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But they sprayed us down; and off we went; in a 777 no less. &lt;/p&gt;&#xA;" OwnerUserId="12842" LastActivityDate="2015-12-31T04:02:39.823" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24051" PostTypeId="1" CreationDate="2015-12-31T06:11:11.927" Score="8" ViewCount="838" Body="&lt;p&gt;I was reading about the ERCO aircraft which apparently has a rudder-aileron linkage system that enables co-ordinated turns without the need for explicit rudder inputs. I've heard of Piper's having bungee cords for the same purpose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Does such a physical linkage lead to perfectly co-ordinated turns under all conditions? Or is it only a coarse approximation &amp;amp; a skilled pilot can execute a better turn?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Why don't a lot more civil aircraft automate this co-ordinated turn feature? Is it because it is hard to automate or more that one wants the pilot to retain the ability to slip when necessary &amp;amp; execute un-coordinated turns sometimes?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Well, even if the latter were true, since 99% of all turns are co-ordinated one could just offer an override for the automated co-ordination feature, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A physical linkage is rather crude, but with a servo / feedback loop wouldn't it be possible to entirely eliminate the rudder pedals?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-06-27T07:55:09.507" LastActivityDate="2016-06-27T07:55:09.507" Title="Can perfect turn coordination automation be achieved by linking rudder to aileron?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;rudder&gt;&lt;ailerons&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24052" PostTypeId="2" ParentId="7982" CreationDate="2015-12-31T08:51:07.037" Score="4" Body="&lt;p&gt;Contrary to some misguided views, all helicopter rotors, both main and tail, are gyroscopic and precess at exactly 90 degrees to the sum of ALL applied moments. The control mechanisms of all helicopters are offset in phase to allow for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because they are gyroscopic, rotors simply do not roll easily. The aerodynamic forces needed to roll the rotor are typically four or five times the forces needed to roll the hull. A violent roll may reflect in the helicopter's torque meter reading because of the extra power needed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of a tail rotor, when a hovering yaw is carried out, the tail rotor axis is being turned about a vertical axis and so it will precess about the roll axis of the helicopter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is accommodated using mechanical coupling in the tail rotor hub, typically by turning the axis of the teetering bearing by something like 45 degrees. When the tail rotor disc rolls, the coupling causes cyclic pitch changes on the tail rotor blades that oppose the roll. As a result the tail rotor follows the hull in a yaw instead of precessing and munching bits off the fin.&lt;/p&gt;&#xA;" OwnerUserId="12845" LastActivityDate="2015-12-31T08:51:07.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24053" PostTypeId="2" ParentId="24051" CreationDate="2015-12-31T13:04:30.593" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/ERCO_Ercoupe&quot; rel=&quot;nofollow&quot;&gt;ERCO Ercoupe&lt;/a&gt; does not have rudder pedals, and even &lt;a href=&quot;https://en.wikipedia.org/wiki/Jessica_Cox&quot; rel=&quot;nofollow&quot;&gt;arm-less pilot Jessica Cox&lt;/a&gt; used one to get a pilots license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest problem that I see with designs like that is when you want to do an uncoordinated maneuver like a cross-wind landing using the wing-low technique. This requires you to turn the controls into the wind (wing low) and then use the rudder in the opposite direction to keep you aligned with the runway. Even crab-style cross-wind landings require you to kick in the rudder to straighten up before touching the pavement. The Ercoupe's gear is designed to handle landing while crabbed, but its a bit rough for the occupants.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another operation that I like to use opposite rudder for is emergency descents. By tilting the aircraft into the dive and using the rudder to keep you going in the right direction you can achieve a pretty decent sink rate without going &quot;into the red&quot;, especially in rough air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another issue I can think of is steering. Tricycle GA aircraft use rudder pedals to steer the aircraft and caster-wheel or tail-dragger aircraft require differential braking and rudder authority. The Ercoupe actually uses the control wheel for taxi, which makes most pilots laugh :).&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2015-12-31T13:10:35.740" LastActivityDate="2015-12-31T13:10:35.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24054" PostTypeId="1" AcceptedAnswerId="24057" CreationDate="2015-12-31T13:08:54.650" Score="9" ViewCount="3072" Body="&lt;p&gt;On a recent flight a passenger locked himself in the lavatory for almost the entire duration of the flight. It was only when the flight was in the final leg of descent that he could be persuaded to come out.&lt;br&gt;&#xA;In similar situations, can the cabin crew open the door from the outside if it is locked from the inside?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorDisplayName="user12485" LastEditDate="2015-12-31T14:24:39.117" LastActivityDate="2016-01-01T22:10:25.347" Title="Could the cabin crew open the lavatory door from outside when someone locked the door from the inside?" Tags="&lt;cabin-design&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24055" PostTypeId="1" CreationDate="2015-12-31T13:34:24.853" Score="20" ViewCount="4014" Body="&lt;p&gt;Isn't ground effect a big factor in STOL operations?  Don't low wings produce greater ground effect than high wings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is it a practical concern, that most real-world STOL operations are in unimproved or slightly-improved locations, and high wings are more likely to clear &quot;runway&quot; obstacles?&lt;/p&gt;&#xA;" OwnerUserId="2012" LastEditorUserId="15311" LastEditDate="2019-02-23T19:38:03.937" LastActivityDate="2019-03-07T23:40:49.253" Title="Why are almost all STOL aircraft high-wing?" Tags="&lt;aircraft-design&gt;&lt;ground-effect&gt;&lt;stol&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24056" PostTypeId="2" ParentId="24054" CreationDate="2015-12-31T14:06:11.273" Score="14" Body="&lt;p&gt;Yes, the flight attendants can lock and unlock the lavatories from the cabin. As far as I know, the specific ways that they do this, which probably vary from one aircraft type to another, aren't published by the airlines as a matter of protecting customers' privacy. Bad day for everybody if a deviant was to use such a method to open an occupied lavatory to get a cheap thrill. &lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2015-12-31T14:06:11.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24057" PostTypeId="2" ParentId="24054" CreationDate="2015-12-31T14:08:58.690" Score="17" Body="&lt;p&gt;Apparently yes. It has been mentioned in a number of places. &lt;a href=&quot;http://lifehacker.com/5673308/how-to-open-an-airplane-lavatory-door-from-the-outside&quot; rel=&quot;noreferrer&quot;&gt;One of the methods given&lt;/a&gt; is pretty simple:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Step 1: Approach locked lavatory&lt;/p&gt;&#xA;&lt;p&gt;Step 2: Lift &amp;quot;LAVATORY&amp;quot; sign&lt;/p&gt;&#xA;&lt;p&gt;Step 3: Slide the knob into the unlocked position&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Thats all to it, though they may vary with the aircraft.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;As @RalphJ points out in the comments, it should go without saying that &lt;strong&gt;unless you are cabin crew&lt;/strong&gt;, you should not be doing this.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-01T22:10:25.347" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24059" PostTypeId="2" ParentId="24055" CreationDate="2015-12-31T14:42:44.767" Score="9" Body="&lt;p&gt;I suspect part of it is due to historical design: High-wing STOL worked in the past so why change it now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, there are numerous reasons why high-wings are good for STOL:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Better visibility, no wings blocking the view below. Helps the pilot see/avoid obstacles on the ground.&lt;/li&gt;&#xA;&lt;li&gt;As you say, high wings also improve clearance over rough ground. This is particularly important on grass strips.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft is more aerodynamically stable. This can be of assistance when operating in difficult conditions and can, in some circumstances, mean that the aircraft is more resistant to crosswinds than it would be for a low-wing design.&lt;/li&gt;&#xA;&lt;li&gt;You mention the ground effect: This is not necessarily a good thing. High-wing designs are not as susceptible to the ground effect and therefore may have better landing performance (less float).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;-edit-&#xA;Oh, and one other thing (that's more of an opinion, though): High-wing aircraft are, in my experience, easier from a practical perspective. STOL aircraft often operate in difficult environments and often carry cargo. With high wings it's easier to get stuff into/out of the cabin.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2015-12-31T14:42:44.767" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24060" PostTypeId="2" ParentId="24055" CreationDate="2015-12-31T14:52:08.853" Score="22" Body="&lt;p&gt;You're correct that the low wings produce more ground effect compared to their high winged counterparts. However, during takeoff and landing, it can result in undesirable handling qualities- the aircraft can 'float' the runway; on contrary, the high wing design is more stable. There are other reasons for STOL aircrafts to have high wing designs, most of which has to do with the location of their operation, as you noted:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Most of them are operated from austere airfields. The high wing location gives some protection from the debris (and obstacles).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For the same reason, engines mounted on the high wings have better protection compared to the low wing mounted ones from FOD ingestion.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Most STOL aircraft use large TE flaps. In case a low wing is adopted (and also if propeller is used, like Twin Otter, for example), the required ground clearance will require long and consequently heavy landing gear. This can be avoided in case of high wing design.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The visibility is better compared to low and mid wings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Historically, STOL aircraft have been high wing. Also, some of the STOL aircraft are (military) cargo aircraft- the high wing means there is no wing spar across the cargo compartment; plus, the low fuselage means easier loading/unloading of cargo.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2015-12-31T14:52:08.853" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24062" PostTypeId="1" CreationDate="2015-12-31T19:11:14.570" Score="7" ViewCount="1561" Body="&lt;p&gt;ADS-B out is available on the 1090 (Mode S) band, and can even be implemented as a firmware update to some Mode S transponders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of 978 ADS-B Out, I believe that it is still necessary to keep operating a Mode C transponder for operations where Mode C is currently required, as noted in &lt;a href=&quot;https://www.youtube.com/watch?v=1LvZy59FhQw&quot; rel=&quot;nofollow&quot;&gt;This video&lt;/a&gt; at 16:25, in order to work with TCAS systems.  Continuing on to 41:24, there is a recommendation stating that if a Mode C transponder fails, it should be replaced with an ADS-B &quot;out&quot; transponder.  Here are my questions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is there such thing as a 978 transponder which will meet ads-b out requirements and eliminate the need for Mode C, or does this recommendation essentially mean that you move to a 1090ES transponder?&lt;/li&gt;&#xA;&lt;li&gt;Perhaps this recommendation is assuming that there was no ads-b out at the time.  Given an aircraft with a failed mode-c transponder, what equipment options which meet the mandates are worth considering for GA aircraft?  Apparently John Zimmerman does not recommend Mode C + 978 out.  It appears he recommends 1090ES.  Either one of these would seem to benefit from having 978 in.  I can see no advantage to 1090ES in, as it appears to offer only a subset of the 978 services, unless it was desired to be able to receive 1090ES air-to-air or our operate outside the US.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="182" LastEditorUserId="19" LastEditDate="2016-01-01T02:43:49.267" LastActivityDate="2016-01-01T16:23:28.650" Title="What are Mode C requirements with ADS-B 978?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;ads-b&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24063" PostTypeId="2" ParentId="24055" CreationDate="2015-12-31T20:51:05.873" Score="1" Body="&lt;p&gt;High wing airplanes have their center of lift above the lateral center of rotation.  This means the majority of the mass of the aircraft is below the lifting surface.  This adds to longitudinal as well as lateral stability--especially at low speeds. Sort of a pendulum effect. Ground effect happens at less than one wingspan.  In small aircraft that's 25 to 40 feet. This would also be reduced at the higher angle of climb that STOL aircraft exhibit.  The only way you could improve the stability of a low winged aircraft in that regard, one would have to drastically increase the wing's dihedral.  This would raise the stall speed slightly, reducing its lifting capacity.  Even though this effect would be very slight, the object of a STOL is to perform short takeoffs and landings.  &lt;/p&gt;&#xA;" OwnerUserId="12851" LastActivityDate="2015-12-31T20:51:05.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24064" PostTypeId="2" ParentId="16020" CreationDate="2015-12-31T20:55:20.563" Score="3" Body="&lt;p&gt;You can instruct or split time with friends but I doubt that you want to do that.&lt;br&gt;&lt;br&gt;Working as a First Officer for a cargo airline is a good way to gain hours. These airlines can be shoddy operations so be careful.  You will not make much money, maybe none at all, but you will get hours and get great experience.  Most cargo airlines fly old, trashy planes with minimal equipment and usually fly into smaller airports.  Weather is a secondary concern in many cases.  In fact, a common joke is: &quot;Why check the weather?  We're going anyway.&quot;  The experience you'll gain from flying old, obsolete equipment into small fields and through terrible weather is extremely valuable and will make you a better pilot!  You will learn more in 250 hours of cargo flying in second-rate equipment than you will just about anywhere else.  I cannot recommend it highly enough!&lt;br&gt;&lt;br&gt;&#xA;Now, the job I've described is difficult to find.  It's a niche that hundreds just like you are willing to pay for (literally pay for a job as a First Officer).  You may have to offer your services for free in exchange for the training the airline is required to give you to make you a crew member.  This is not cheap as it requires the company to burn hundreds of gallons of fuel to do your flight training!  Your existence becomes one of a pilot for the company...you will never drink, you'll live your life within one hour of the airport, and you will never take a vacation.  For as long as you're a FO, your only purpose in life is to gain hours, nothing (and I mean &lt;strong&gt;nothing&lt;/strong&gt;) else.  I cannot stress this enough.  Most small companies are doing you a favor by even considering you for an FO position.&lt;br&gt;&lt;br&gt;It is important to realize that simply because a company makes you a FO does not mean you can log flight time!  You must be flying a plane that requires an FO &lt;strong&gt;and&lt;/strong&gt; the kind of flying you're doing must require a FO.  For example, a properly rated pilot can fly a Metroliner as a single pilot as long as he's flying cargo.  As soon as a passenger* boards the plane, that single-pilot must either have an autopilot or a First Officer.  This is where you come in. A lot of these older planes have had their autopilots removed by the cargo companies!  They cost too much to maintain and each pilot must be trained on the operation of each autopilot the company uses.  It's cheaper to remove them than it is to conduct the training and maintain the equipment.&lt;br&gt;&lt;br&gt;&#xA;*A passenger is anyone who is not a required crew member.  You would be considered a passenger if you flew in the right seat without being trained a First Officer.  Sometimes a company employee can ride along with a single pilot under circumstances.  You cannot exploit this loophole to gain experience &lt;strong&gt;legally&lt;/strong&gt;, though many people do log time and &quot;build hours&quot; this way.  The vast majority are never caught and most are told it's legal by companies selling time to low time pilots.  The FAA does not seem to enforce this at all.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-01-02T18:58:03.940" LastActivityDate="2016-01-02T18:58:03.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24065" PostTypeId="2" ParentId="23753" CreationDate="2015-12-31T21:57:32.287" Score="-3" Body="&lt;p&gt;Short answer: NO&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long answer: In a flight where the CFI is certificated to provide instruction and the two are sitting in pilot seats then the PIC may log any part of that flight as dual instruction.  It does not require the CFI to actually say a word in order for it to count as dual; even if he's merely observing, if something bad happens he'll open his mouth or take controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part 135 is more about requirements for operations; it does not affect flight instruction, which is a part 91 regulated activity.&lt;/p&gt;&#xA;" OwnerUserId="12839" LastEditorUserId="7532" LastEditDate="2016-01-01T00:27:51.650" LastActivityDate="2016-01-01T00:27:51.650" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24067" PostTypeId="2" ParentId="21961" CreationDate="2015-12-31T22:11:34.610" Score="1" Body="&lt;p&gt;The Lycoming HIO-360 is a horizontally-mounted version of the IO-360.  (H for Horizontal).  It reaches its power band peak and has a lower peak at different RPM for that reason.  This is often the case when you work against gravity / work with gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some helicopter engines are designed with thinner cylinder walls for lighter weight. (IO-360-J2A for the Robinson R22 for example).  These are further derated because of the weaker cylinder walls.  Note that there is no H designation here because a)H is for horizontal and this is not one, and b)H is NOT for helicopter :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E&lt;/p&gt;&#xA;" OwnerUserId="12839" LastActivityDate="2015-12-31T22:11:34.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24068" PostTypeId="2" ParentId="24062" CreationDate="2016-01-01T02:32:59.180" Score="3" Body="&lt;p&gt;For Class A,B and C, you'll need a Mode C transponder as per the present regulations (unless cleared by ATC). From 14 CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1215&quot; rel=&quot;nofollow noreferrer&quot;&gt;§91.215 ATC transponder and altitude reporting equipment and use&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§91.215   ATC transponder and altitude reporting equipment and use.&lt;/p&gt;&#xA;&lt;p&gt;(b) All airspace. Unless otherwise authorized or directed by ATC, no person may operate an aircraft in the airspace described in paragraphs (b)(1) through (b)(5) of this section, unless that aircraft is equipped with an operable coded radar beacon transponder ... and that aircraft is equipped with automatic pressure altitude reporting equipment having a Mode C capability that automatically replies to Mode C interrogations by transmitting pressure altitude information in 100-foot increments. This requirement applies—&lt;/p&gt;&#xA;&lt;p&gt;(1) All aircraft. In Class A, Class B, and Class C airspace areas;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;FAA also addresses this in its &lt;a href=&quot;https://www.faa.gov/nextgen/programs/adsb/faq/#7&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAQs regarding ADS-B&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Will Mode C transponders be required indefinitely?&lt;/p&gt;&#xA;&lt;p&gt;The FAA is considering additional changes in the national airspace system, such as for TCAS. These changes, may at some future date, reduce or eliminate the need for transponder equipage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, at present, you'll need Mode C anyway.&lt;/p&gt;&#xA;&lt;p&gt;Also, you'll need 1090ES in Class A. From FAA FAQs:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Aircraft that fly internationally and aircraft that require TCAS (Traffic Collision Avoidance System) are already operating with Mode S transponders and many have older versions of ADS-B Out on 1090ES MHz. Aircraft flying in Class A airspace must operate on the 1090ES MHz frequency. General aviation users who choose the UAT (978 MHz) link may take advantage of the ADS-B traffic, weather, and aeronautical services that are transmitted on the UAT frequency at no charge but must retain their current ATCRBS transponder. Mode S, 1090-ES users can operate in all airspace, but cannot receive FIS-B services.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I agree with you that there are a number of services (through FIS-B) for 978 UAT. In that case, (if you are not going above 18,000 ft) I suggest you check the availability of UAT receivers before taking a decision.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-01T02:32:59.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24070" PostTypeId="1" CreationDate="2016-01-01T09:01:49.183" Score="14" ViewCount="3425" Body="&lt;p&gt;What process do pro pilots have to go through with their passports when on the clock?  Are they afforded any shortcuts or do they have to go through security EVERY SINGLE TIME?  &lt;/p&gt;&#xA;" OwnerUserId="870" LastActivityDate="2016-01-02T10:17:06.490" Title="Do professional pilots have to show their passports every single time when flying back &amp; forth between the same airports?" Tags="&lt;airport&gt;&lt;airline-pilot&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24071" PostTypeId="2" ParentId="24070" CreationDate="2016-01-01T10:44:38.950" Score="7" Body="&lt;p&gt;Pilots (and aircrew) usually go through an expedited security screening, usually separate from passengers, in order to reduce wait times. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, US TSA has a program called the Known Crewmember Program that allows pilots and crew members to bypass normal (passenger) security line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots (and aircrew) have to show the documents as required by the local authorities. Usually, this will be the passport/visa or General Deceleration. This varies from country to country.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-01T10:44:38.950" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24072" PostTypeId="2" ParentId="21264" CreationDate="2016-01-01T11:03:59.887" Score="3" Body="&lt;p&gt;Relying on physics, causing a mass to execute a circular path requires a suitable centripetal force. In an airplane in a banked balanced turn, this comes from the inward component of lift due to the bank angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if the turn is not properly co-ordinated, there can be additional contributions to the centripetal force from the power plant thrust no longer being directed tangentially and sidethrust on the airframe due to slip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The extreme case is the flat turn where the wings remain level and the power plant thrust has an inward component due to the sideslip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, apart from an airplane having vectoring thrust, the only reason for a thrust sideslip angle I can think of is that many single airscrew airplanes have built-in sidethrust to counteract engine torque. However there is no requirement for the engine sidethrust angle to equal the slip angle, so in that case the assumption that the two angles are the same cannot be valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust line of an airscrew doesn't change with slip. The slip causes asymmetric thrust on the blades which precesses gyroscopically so the airscrew creates a couple which tends to increase the slip angle.     &lt;/p&gt;&#xA;" OwnerUserId="12845" LastActivityDate="2016-01-01T11:03:59.887" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24073" PostTypeId="1" CreationDate="2016-01-01T16:09:32.557" Score="10" ViewCount="5704" Body="&lt;p&gt;Are pilots at Airlines typically assigned to fly a single Type in a given month / year or do they get switched routinely between multiple types of aircraft as per scheduling convenience?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. Is it common to, say, fly a B-747 &amp;amp; then return flying a B-777 etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How about more extreme changes like switching between Boeings &amp;amp; Airbuses or Turbojet / Turboprop etc.? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess that begs the question whether pilots typically are certified &amp;amp; current across multiple Types? How common is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking more for comments about what is operating practice across airlines rather than a hard rule, which I guess does not exist. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-06-22T11:45:33.407" LastActivityDate="2019-09-22T15:19:01.310" Title="How frequently are airline pilots switching between aircraft types (e.g. Airbus, Boeing, etc)?" Tags="&lt;airline-operations&gt;&lt;airlines&gt;&lt;type-ratings&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24074" PostTypeId="2" ParentId="24062" CreationDate="2016-01-01T16:23:28.650" Score="2" Body="&lt;p&gt;1.) Not at this time, but someday maybe. It is reasonable that transponders will someday become obsolete with the advent of &lt;a href=&quot;http://www.faa.gov/nextgen/&quot; rel=&quot;nofollow&quot;&gt;NextGEN&lt;/a&gt; infrastructure (including ADS-B) being implemented worldwide. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The transponder lends itself to a radar based ATC system for determining 'who' and 'where' aircraft are located. Although the radar can determine a 'where', the transponder fills in the 'who'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NextGEN is planning to do away with radars (for the most part). ADB-S (a major component of NextGen) can provide ATC both the 'who' and the 'where' (and then some) on its own (no radar needed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It could be years or decades before transponder requirements are relaxed however. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2.) '978 in' or 'ADS-B in' is a compelling reason for installing a UAT. I'd wager that even aircraft meeting the 2020 mandate with a 1090ES mode S transponder will eventually install UAT receivers. One advantage, however, to 1090ES is it is the only recognized ADB-S equipage anywhere outside of the USA at this time.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2016-01-01T16:23:28.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24075" PostTypeId="1" CreationDate="2016-01-01T17:27:54.997" Score="7" ViewCount="1726" Body="&lt;p&gt;What happened to the B737.X design that depicted a downward nose much like the B787? It is not apparent in the B737 Max 8.&lt;/p&gt;&#xA;" OwnerUserId="12859" LastEditorUserId="4474" LastEditDate="2016-01-02T00:12:02.127" LastActivityDate="2016-01-02T00:12:02.127" Title="What happened to the Boeing 737.X design?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24076" PostTypeId="2" ParentId="24075" CreationDate="2016-01-01T17:59:53.997" Score="10" Body="&lt;p&gt;&lt;a href=&quot;http://www.airlinereporter.com/tag/boeing-737-x/&quot;&gt;Boeing was considering&lt;/a&gt; designing an all-new airplane to replace the 737 around 2020. Having been in production for over 40 years and through 3 major versions, it seemed like it was finally time to leave the 737 type behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, Airbus decided to upgrade the main competition to the 737 to create the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320neo_family&quot;&gt;A320neo&lt;/a&gt;. The A320neo is more efficient than the 737NG and will be entering service in 2016. Boeing watched orders accumulate for the A320neo and felt that they would lose too much market share in the single aisle market if they waited until 2020 to introduce a new plane to compete with the A320neo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high number of orders for the A320neo convinced Boeing to scrap the new plane concept, and focus on just new engines for the 737, in order to get a plane on the market to compete with the A320neo. This allowed the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX&quot;&gt;737MAX&lt;/a&gt; to be scheduled to enter service in 2017, less than 2 years after the A320neo. While the MAX does not have as many improvements as a new design would have, it has helped narrow the gap in orders to the A320 series. A new plane still 5 or 6 years away while the A320neo enters service would not have nearly as many orders, meaning the Airbus would be quickly increasing their market share with the A320neo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar situation has happened with the 777, although it is still a much more recent design. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777X&quot;&gt;777X&lt;/a&gt; is a more significant redesign than the 737MAX, but the update is needed to compete with the new A350 that is already in service.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-01-01T21:32:34.157" LastActivityDate="2016-01-01T21:32:34.157" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24077" PostTypeId="2" ParentId="24073" CreationDate="2016-01-01T18:36:40.687" Score="14" Body="&lt;p&gt;Airline pilots are typically only certified and current on one type. It is rare for a pilot to be certified and current on multiple types because they must do re-current training and check rides for each type in order to remain current and legal. The extra cost for training and check rides would not make financial sense to an airline trying to be competitive with other airlines.  &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-01-01T18:36:40.687" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24078" PostTypeId="2" ParentId="24073" CreationDate="2016-01-01T21:18:31.953" Score="1" Body="&lt;p&gt;A pilot at an airline usually flies one type of aircraft at one time, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1784/how-many-type-ratings-are-pilots-allowed-to-hold-at-once&quot;&gt;but can hold many type ratings at the same time&lt;/a&gt;. There are common type ratings between similar aircraft (Some versions of the 777 and 787 as well as the A320 family). With Airbus planes besides the A380, they require a little less transition time between the types because they are made to be very similar. The A320 has a common type rating as well as the &lt;a href=&quot;http://www.airbus.com/newsevents/news-events-single/detail/the-common-type-rating-is-approved-for-a350-xwb-and-a330-pilot-training/&quot; rel=&quot;nofollow noreferrer&quot;&gt;A350 XWB and A330&lt;/a&gt;; Boeing has the 767/777 and 787 type ratings from what I hear. You can't have a common type rating between Boeings and Airbuses because they have totally different cockpit and control configurations.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="14897" LastEditDate="2019-09-22T15:19:01.310" LastActivityDate="2019-09-22T15:19:01.310" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="24079" PostTypeId="1" CreationDate="2016-01-01T23:19:34.590" Score="6" ViewCount="158" Body="&lt;p&gt;Is it common for carriers to have separate certification for Analog cockpits versus Glass (digital) cockpits?&lt;/p&gt;&#xA;" OwnerUserId="12859" LastEditorUserId="167" LastEditDate="2016-01-03T05:13:03.497" LastActivityDate="2016-01-03T05:13:03.497" Title="Is it common for carriers to have separate certification for analog versus glass cockpits?" Tags="&lt;airline-operations&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24080" PostTypeId="2" ParentId="24079" CreationDate="2016-01-02T00:23:17.847" Score="4" Body="&lt;p&gt;Pilot type ratings are usually same for both versions (analog and digital cockpits) of the same aircraft as far as regulations are concerned. For transition to glass cockpit, you may have to take a Electronic Flight Instrumentation Course (or differences training course).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases of transition (for example, EASA  ATR 42/72 (glass cockpit, non &#xA;ECL) to any other ATR 42/72 'classic'), a full type rating training course is required; however, the type rating is still the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, see the &lt;a href=&quot;http://registry.faa.gov/TypeRatings/&quot; rel=&quot;nofollow&quot;&gt;FAA&lt;/a&gt; and &lt;a href=&quot;http://easa.europa.eu/system/files/dfu/List_of_Aeroplanes_--_Class_and_Type_Ratings_and_Endorsement_List-12032014.pdf&quot; rel=&quot;nofollow&quot;&gt;EASA&lt;/a&gt; type rating lists.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-02T00:23:17.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24082" PostTypeId="1" CreationDate="2016-01-02T05:30:40.407" Score="10" ViewCount="667" Body="&lt;p&gt;Another answer on SE Aviation (&lt;a href=&quot;https://aviation.stackexchange.com/questions/13547/why-pilots-would-leave-the-cockpit-in-a-short-flight&quot;&gt;Why pilots would leave the cockpit in a short flight?&lt;/a&gt;&#xA;) had this bit of information in it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The cockpit of some airliners lacks a lavatory.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Isn't is more the other way around: i.e. A Lavatory inside a cockpit is a rarity?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which airliner cockpits have an entire Lavatory &lt;strong&gt;inside&lt;/strong&gt; them? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I always thought the Flight Crew came out to use the forward-most Business / First class lavatory. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-06-22T11:46:23.463" Title="Which air transport aircraft have a lavatory included inside the cockpit?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24083" PostTypeId="1" AcceptedAnswerId="24087" CreationDate="2016-01-02T05:35:59.983" Score="21" ViewCount="2812" Body="&lt;p&gt;(1) What are the legal considerations for skydiving into clouds? I see many skydivers did fall into and out clouds in online videos. However, the clouds are mostly scattered or thin-layered. How about in widespread hard-IMC, say OVC 008? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) What about maintaining the actual safety? How does a skydiver maintain attitude and stable position in IMC and not disoriented? and separation from other traffic?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: The legal consideration of my context is within US, but open to legal regulations worldwide.  &lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-01-03T01:16:44.317" LastActivityDate="2019-03-12T02:58:56.553" Title="Is skydiving in IMC (through clouds) legal and safe?" Tags="&lt;instrument-flight-rules&gt;&lt;skydiving&gt;&lt;imc&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24085" PostTypeId="2" ParentId="24070" CreationDate="2016-01-02T10:17:06.490" Score="5" Body="&lt;p&gt;Pilot and author Patrick Smith covers this subject in his online column &lt;a href=&quot;http://www.askthepilot.com/essaysandstories/terminal-madness&quot;&gt;Ask the Pilot&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;But of all the half-baked measures we’ve grown accustomed to, few are sillier than the policy decreeing that pilots and flight attendants undergo the same x-ray and metal detector screening as passengers...An airline pilot who once flew bombers armed with nuclear weapons is not to be trusted and is marched through the metal detectors. But those who cater the galleys, sling the suitcases, and sweep out the aisles, have for years been able to saunter onto the tarmac unmolested.  If there has been a more ringing, let-me-get-this-straight scenario anywhere in the realm of airport security, I’d like to hear it.&quot;&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2016-01-02T10:17:06.490" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24086" PostTypeId="2" ParentId="24082" CreationDate="2016-01-02T11:42:43.073" Score="10" Body="&lt;p&gt;As far as I know, some Boeing 747-400s (BA, Air France) had lavatories inside the cockpit. Apparently, Boeing 747-8 Intercontinental &lt;a href=&quot;http://airwaysnews.com/html/cabins-and-cockpits/lufthansa/lufthansa-boeing-747-8-intercontinental-flight-deck-and-flight-attendant-crew-quarters-2012/20861&quot;&gt;has a lavatory behind the cockpit door&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... Lufthansa Boeing 747-8 Intercontinental is unique in that the flight deck crew have their own lavatory, ... behind the locked cockpit door, allowing for extra security and a non-disruptive cabin service involving trolleys blocking the door. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-02T11:42:43.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24087" PostTypeId="2" ParentId="24083" CreationDate="2016-01-02T11:53:26.557" Score="20" Body="&lt;p&gt;It is not legal to conduct skydiving into clouds, atleast in US. From 14 CFR &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=9db3e76f75bbd4650171aaff30810b08&amp;amp;mc=true&amp;amp;node=se14.2.105_117&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;§105.17   Flight visibility and clearance from cloud requirements&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No person may conduct a parachute operation, and no pilot in command of an aircraft may allow a parachute operation to be conducted from that aircraft—&lt;/p&gt;&#xA;&lt;p&gt;(a) Into or through a cloud, or&lt;/p&gt;&#xA;&lt;p&gt;(b) When the flight visibility or the distance from any cloud is less than that prescribed in the following table:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HW8rH.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HW8rH.png&quot; alt=&quot;Skydiving&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Is it safe? Probably. The chances of mid-air collision are pretty small, but they can happen &lt;a href=&quot;https://en.wikipedia.org/wiki/Mid-air_collision&quot; rel=&quot;noreferrer&quot;&gt;as is does with aircraft&lt;/a&gt;. Midair collisions between skydivers and &lt;a href=&quot;http://www.bbc.com/news/world-us-canada-26508189&quot; rel=&quot;noreferrer&quot;&gt;between aircraft and skydivers&lt;/a&gt; are rare, but not unheard of. There has also been reports of &lt;a href=&quot;http://www.37000feet.com/report/399935/Pilot-of-PA30T-has-near-midair-collision-with-skydivers-descending-through-scattered&quot; rel=&quot;noreferrer&quot;&gt;near misses between aircraft and skydivers through clouds&lt;/a&gt;. So, its better to be safe.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-03T03:34:50.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24088" PostTypeId="2" ParentId="24083" CreationDate="2016-01-02T14:22:06.610" Score="16" Body="&lt;p&gt;Is it legal? No. Skydiving is a VFR operation, FAA regulations ( assuming the USA ) clearly say no jumping through clouds. Few jump planes are IFR equipped to get up there anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it safe? Yes. Done it plenty of times myself on partly overcast days. The chances of hitting another aircraft in freefall are miniscule, and skydivers basically have no chance to see and avoid an aircraft anyway - the speeds and angles are too high. The pilot announces what's happening to other traffic and it's over in a minute. Determining the exit point with &gt;50% cloud cover is not easy but GPS has largely eliminated that issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying a parachute through cottonball-cumulus clouds happens, it's kinda boring. Going around tall formations is much more interesting but doesn't really qualify as &quot;into&quot;. If the weather systems are strong enough to affect a parachute's handling you won't find any canopies up there as everyone is in the local bar.&lt;/p&gt;&#xA;" OwnerUserId="9516" LastActivityDate="2016-01-02T14:22:06.610" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24090" PostTypeId="2" ParentId="2045" CreationDate="2016-01-02T16:59:58.977" Score="0" Body="&lt;p&gt;Sometimes these flight schools offer contests also and those who win the contest are offered free flight lessons or discovery flights. That too is just a way to bring in the students and to motivate them to learn flying and with this schools get success most of the times. Though the profit might be marginal.&lt;/p&gt;&#xA;" OwnerUserId="12867" LastActivityDate="2016-01-02T16:59:58.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24091" PostTypeId="2" ParentId="2045" CreationDate="2016-01-02T17:07:39.173" Score="0" Body="&lt;p&gt;When I was a child (under 13 years old) I visited an airplane museum in Oshkosh, WI USA and they had free flights in a 2 seat Cessna with some old guy and you are able to control the plane with his guidance but it would be no different then actually flying it. I went up for 20 minutes or so and he taught me how to maneuver right/left/up/down. I suggest visiting airplane museums and asking local hobby places for anyone who has a small airplane. I doubt you're under 13 and live in Oshkosh Wisconsin but museums would be a decent place to start. I will also say if you like airplanes enough to want to be a pilot without caring for salary I think you will love flying it was very cool. &lt;/p&gt;&#xA;" OwnerUserId="12864" LastActivityDate="2016-01-02T17:07:39.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24092" PostTypeId="1" AcceptedAnswerId="24104" CreationDate="2016-01-02T18:29:36.933" Score="6" ViewCount="600" Body="&lt;p&gt;What does the word 'effort' mean in this context?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gOqlz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gOqlz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-01-02T18:45:34.350" LastActivityDate="2016-01-03T03:18:21.070" Title="Why is this chart called a Short Field Effort Takeoff Ground Roll and not simply a Short Field Takeoff Ground Roll?" Tags="&lt;terminology&gt;&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24093" PostTypeId="2" ParentId="2045" CreationDate="2016-01-02T19:04:06.860" Score="0" Body="&lt;p&gt;Go to your local field.  Make friends with airplane owners.  Offer to wash planes after a flight (clean off bugs and oil), vacuum interiors, clean windows (with soap and water ONLY), or, if the owners trust you, to wash the exterior of the plane.  Offer these services in exchange for some short flights at owner's convenience.  It may take weeks or months, but you will get a free flight somewhere along the line.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2016-01-02T19:04:06.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24094" PostTypeId="1" AcceptedAnswerId="24095" CreationDate="2016-01-02T19:12:53.287" Score="4" ViewCount="406" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TnCiR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TnCiR.jpg&quot; alt=&quot;IFE showing map of arrival into Paris from Dubai&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was taken in a Emirates flight Dubai-Paris in December 2015.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are on these 2 locations?&lt;/li&gt;&#xA;&lt;li&gt;Why these numbers? Are they dates?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7831" LastEditorUserId="14897" LastEditDate="2021-05-02T20:55:48.053" LastActivityDate="2021-05-02T20:55:48.053" Title="What are the points 1864 and 1922 on this in-flight map?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2016-01-08T18:41:35.960" ContentLicense="CC BY-SA 3.0" />
  <row Id="24095" PostTypeId="2" ParentId="24094" CreationDate="2016-01-02T20:42:28.863" Score="13" Body="&lt;p&gt;The number may stands for the year of the ships sunk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1864 may correspond to &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/CSS_Alabama&quot; rel=&quot;nofollow&quot;&gt;CSS Alabama&lt;/a&gt;&lt;/em&gt; (Arabic: ألاباما), a Confederate States Navy Screw sloop which was sunk on June 1864 at the Battle of Cherbourg. The wreck is at &lt;a href=&quot;https://tools.wmflabs.org/geohack/geohack.php?pagename=CSS_Alabama&amp;amp;params=49_45_9_N_1_41_42_W_&quot; rel=&quot;nofollow&quot;&gt;49°45′9″N, 1°41′42″W&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1922 may correspond to &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/SS_Egypt&quot; rel=&quot;nofollow&quot;&gt;SS Egypt&lt;/a&gt;&lt;/em&gt; (Arabic: مصر), a British ocean liner which was sunk after a collision with &lt;em&gt;SS Seine&lt;/em&gt; on 20 May 1922. The wreck is located near &lt;a href=&quot;http://www.plimsoll.org/resources/SCCLibraries/WreckReports2002/20532.asp?view=text&quot; rel=&quot;nofollow&quot;&gt;48°10′N, 5°29′W&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As @mins mention in comment, there are other wrecks appearing on the map in IFE, including &lt;em&gt;Mary Rose&lt;/em&gt; 1545 near Portsmouth and &lt;em&gt;San Pedro de Alcantara&lt;/em&gt; 1786 near Peniche.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2016-01-06T15:16:38.120" LastActivityDate="2016-01-06T15:16:38.120" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24096" PostTypeId="2" ParentId="8438" CreationDate="2016-01-02T20:49:14.320" Score="3" Body="&lt;p&gt;The definitive answer is YES, as demonstrated by this guy who built one: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/wg8ZbiC9IBw?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="12869" LastActivityDate="2016-01-02T20:49:14.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24097" PostTypeId="1" AcceptedAnswerId="24098" CreationDate="2016-01-02T21:08:55.233" Score="15" ViewCount="15351" Body="&lt;p&gt;In a carbureted engine at higher altitudes, less dense air means there is less air entering the engine. Wouldn't we want the mixture to be full rich to allow the maximum air into the engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the engine will become rough if we don't lean the engine. I'm asking what is going on? It seems like a decrease in air means we would need to open the mixture not close it. &lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-02-01T11:02:33.237" Title="Why do we lean the mixture when the air become less dense?" Tags="&lt;aircraft-systems&gt;" AnswerCount="4" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24098" PostTypeId="2" ParentId="24097" CreationDate="2016-01-02T21:25:59.383" Score="16" Body="&lt;p&gt;The decrease in air means less oxygen. If the fuel is burnt at &quot;rich&quot; there would not be enough oxygen in the air to burn some of the fuel, thus reducing efficiency, increasing the risk of carbon monoxide, and adding grime to the exhaust system. That is why &quot;lean&quot; is used for high altitudes, to burn efficiently and safely.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-02T21:25:59.383" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24099" PostTypeId="1" AcceptedAnswerId="24103" CreationDate="2016-01-02T21:34:31.720" Score="4" ViewCount="331" Body="&lt;p&gt;If you look at this chart you see we subtract 3 minus 1, 9 minus 2, and 30 minus 4 in the example calculation. My question is, why do we subtract these numbers? Do we subtract the same numbers each time? Nowhere on the performance chart does it give any explanation! &lt;a href=&quot;https://i.stack.imgur.com/AVxTm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AVxTm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Jrf6.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Jrf6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="167" LastEditDate="2016-01-03T05:14:36.973" LastActivityDate="2016-01-03T05:14:36.973" Title="Why do you need to subtract when using a climb/descent performance chart for an altitude other than sea level?" Tags="&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24100" PostTypeId="2" ParentId="23946" CreationDate="2016-01-02T21:44:48.777" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Does the ARCA hoverboard violate known limits on small-diameter electric fans?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;1) The max theoretical static thrust that can be obtained with an Electric Ducted Fan characterized by: Diameter = 120 mm and Power = 272 hp / 36 = 5.63 kW is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1.2 kg/m^3 x (5.63 kW)^2 x pi x (120 mm)^2/2)^(1/3) = 9.7 kgf&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I used the formula that gives the max possible static thrust as a function of power and the diameter of the propeller. The overall efficiency is considered 100%. For realistic efficiencies, smaller than 1, the Power is not 5.63 kW but 5.63 x efficiency)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you see, 36 fans, that draw a total of 272 hp, can lift in theory 9.7 kg x 36 = 349 kg, well above the 192 kg of ArcaBoard (including the weight of the pilot). &lt;strong&gt;No limit is violated.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the configuration with 36, 120 mm diameter, rotors is bad because the same formula I used above says that a single 26 inch propeller powered by a 5.63 kW motor generates:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1.2 kg/m^3 x (5.63 kW)^2 x pi x (26 inch)^2/2)^(1/3) = 30 kgf&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In consequence, eight 5.63 kW motors, turning 26 inch propellers, will draw only 45 kW (60.4 hp) and lift 240 kg, more than the max mass of ArcaBoard in flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small diameter propellers are simply inefficient for generating static thrust. This is the reason helicopters have large rotors. &lt;strong&gt;Hovering boards like ArcaBoard, also perfectly realizable, have no future because they waste an enormous amount of power&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) A well designed and built electric hoverboard was made by C. A. Duru. It requires considerably less power than ArcaBoard and flies much better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A comparison between the hoverboard of Catalin Alexandru Duru (see: the video) and that made by Dumitru Popescu from ARCA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Bfa9HrieUyQ?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&#xA;&lt;a href=&quot;https://www.youtube.com/watch?v=Bfa9HrieUyQ&quot; rel=&quot;nofollow&quot;&gt;Video: C.A. Duru flying&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Catalin Alexandru Duru's hoverboard&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;8 rotors, 4.5 kW each&lt;/li&gt;&#xA;&lt;li&gt;Total Power: 36 kW = 48.3 hp&lt;/li&gt;&#xA;&lt;li&gt;Payload: 1 person&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dumitru Popescu's hoverboard&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;36 rotors, 5.63 kW each &lt;/li&gt;&#xA;&lt;li&gt;Total power: 203 kW = 272 hp &lt;/li&gt;&#xA;&lt;li&gt;Payload: 1 person&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In conclusion, ArcaBoard is nothing else but a badly designed hoverboard that requires an enormous power, 272 hp, to carry a man while 48.3 hp are enough for such a job, as demonstrated by C. A. Duru.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.rcgroups.com/forums/showthread.php?t=2568879&quot; rel=&quot;nofollow&quot;&gt;Source: A multicopter with 36 propellers that carries a man&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2016-01-02T22:07:47.623" LastActivityDate="2016-01-02T22:07:47.623" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24101" PostTypeId="1" AcceptedAnswerId="24102" CreationDate="2016-01-02T22:01:38.977" Score="11" ViewCount="7110" Body="&lt;p&gt;The ailerons help the plane to bank left/right by increasing lift to one wing and decreasing in another. Likewise, the rudder also helps in turning the plane by yawing and deflecting the nose right/left. So their performances sound quite similar(i.e. to make a turn)? Then, why should we keep both of them?&lt;p&gt;Like in a ship or motorboat there is a rudder only and no ailerons.&lt;p&gt;&lt;p&gt;Are ailerons present for quicker operation and rudder for extra support and stabilization only?&lt;/p&gt;&lt;/p&gt;&#xA;" OwnerUserId="12871" LastEditorUserId="15311" LastEditDate="2017-12-25T19:59:40.323" LastActivityDate="2020-12-25T18:41:37.243" Title="Are the functions of ailerons and rudder similar?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;control-surfaces&gt;&lt;rudder&gt;&lt;ailerons&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24102" PostTypeId="2" ParentId="24101" CreationDate="2016-01-02T22:25:23.383" Score="29" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;:&lt;/p&gt;&#xA;&lt;p&gt;Rudder and ailerons have different purposes and control rotation about two different axis. However a rotation about one axis induces a usually unwanted rotation on the other one. In order to rotate exclusively about the desired axis, the other control must be used to cancel the secondary rotation. This is called coordination of controls.&lt;/p&gt;&#xA;&lt;p&gt;Rudder and ailerons are not the only controls requiring coordination, elevators and throttle actions must be coordinated too, to prevent a change in altitude to result in a change in speed and vice-versa.&lt;/p&gt;&#xA;&lt;p&gt;The rudder is mostly used to:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Limit yaw movements for safety (&lt;a href=&quot;https://www.boldmethod.com/learn-to-fly/aerodynamics/dutch-roll/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dutch roll&lt;/a&gt;) and comfort.&lt;/li&gt;&#xA;&lt;li&gt;To force the aircraft in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Crosswind_landing&quot; rel=&quot;nofollow noreferrer&quot;&gt;crab&lt;/a&gt; (heading not aligned with course), while the weather vaning effect tends to orient the aircraft with the airflow (e.g. for a cross-wind landing).&lt;/li&gt;&#xA;&lt;li&gt;To force the aircraft to face the airflow when performing a turn. We'll talk about this below.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.empire-aviation.com/flight-instructors/john-e-mclain/understanding-the-use-of-rudder.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Understanding the use of rudder&lt;/a&gt; for a more comprehensive explanation.&lt;/p&gt;&#xA;&lt;p&gt;Ailerons are used to turn, but for a non-small turn an unwanted adverse yaw, opposite to the turn, develops and moves the aircraft away from the airflow (crab), the rudder is used to cancel this crab angle and make the aileron-initiated turn effective.&lt;/p&gt;&#xA;&lt;p&gt;The availability of a yaw damper relieves the pilot from the duty of coordinating rudder with ailerons in a turn. The yaw damper controls the rudder for stability purposes, and at the same time it maintains the aircraft longitudinal axis into the relative wind without pilot action.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Detailed answer&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;While it is intuitive to think a turn is triggered by yawing the aircraft and keeping the wing horizontal (like a car), this method is actually ineffective with a rudder of the normal size. The rudder forces the aircraft to change its heading (yaw) but the flight continues more or less in the same direction, the aircraft now moving crabbed. This is specially true as speed and altitude increase and rudder aerodynamic force becomes smaller compared to other factors like inertia.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Banking turns the aircraft&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;An aircraft is turned by rolling (banking) the wing. When the aircraft spins about the roll axis, the direction of the lift is changed (A/B below). Like any force, the lift vector can be broken down into components (B):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eJnS9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eJnS9.png&quot; alt=&quot;Coordinated turn&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The horizontal component of the lift moves the aircraft away from its original path and the aircraft turns around some point. (Note the vertical component, which still opposes the weight, is now smaller, and a non-small turn also requires adding engine power to maintain altitude.)&lt;/p&gt;&#xA;&lt;p&gt;However something quite undesirable happens (C): To roll the wing, the upper aileron has to create more lift than the lower one. Lift is created by deflecting the airflow, and this action has a cost: The disturbed airflow creates &lt;a href=&quot;https://aviation.stackexchange.com/questions/77868/helicopter-flight-what-is-the-reason-for-decrease-in-induced-drag-with-increase&quot;&gt;'induced' drag&lt;/a&gt;. This drag is different from the &lt;a href=&quot;https://www.boldmethod.com/blog/lists/2018/07/how-the-5-types-of-drag-affect-your-airplane/&quot; rel=&quot;nofollow noreferrer&quot;&gt;other drags&lt;/a&gt;, it's not due to the friction or the shape of the aileron, but to the deflection of the airflow by the aileron, and increases with the amount of lift created.&lt;/p&gt;&#xA;&lt;p&gt;Like aileron lift, aileron induced drag is larger on the upper wing, that is on the outer side of the turn. As there is a drag differential, the wing is no more balanced and wants to yaw on the right, opposite to what we want. This force is known as the &amp;quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw&quot; rel=&quot;nofollow noreferrer&quot;&gt;adverse yaw&lt;/a&gt;&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;A part of the adverse yaw is balanced by the weather vaning tendency of the aircraft, due to the action of the fuselage and the rudder. However this only compensates partially for the yaw. All these forces makes the aircraft turn a bit, but crabbed, as seen in picture D. This situation where the aircraft is not aligned with the airflow is an &amp;quot;uncoordinated turn&amp;quot;, it is very inefficient, slows the aircraft and stresses the airframe.&lt;/p&gt;&#xA;&lt;p&gt;This is were some action on the rudder is required: The pilot adds some left rudder to completely cancel the adverse yaw created by the ailerons and align the fuselage with the airflow (E). Doing this any &lt;a href=&quot;http://www.boldmethod.com/learn-to-fly/aerodynamics/slip-skid-stall/&quot; rel=&quot;nofollow noreferrer&quot;&gt;slip and skid&lt;/a&gt; motion is also minimized. This is known as performing a &lt;a href=&quot;https://en.wikipedia.org/wiki/Coordinated_flight#Coordinating_the_turn&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;coordinated turn&lt;/em&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;As visible on the figure E, the horizontal component of the lift, the one pulling the aircraft towards the center of the turn, is constantly reoriented in the direction of the center, contrary to the case of the uncoordinated turn (D).&lt;/p&gt;&#xA;&lt;p&gt;Rolling the wing is a very effective way of turning the aircraft, but needs some rudder correction to account for the induced drag moving the aircraft longitudinal axis away from the airflow direction.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Ailerons deflection reduced in the turn&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Note that when the desired bank angle is reached, the pilot reduces the ailerons deflection. The excess of lift and drag on the upper wing decreases too, as does the adverse yaw. The rudder deflection can be reduced too.&lt;/p&gt;&#xA;&lt;p&gt;Normally the aircraft should maintain its bank and continue to turn with ailerons in neutral position, due to the upper wing flying faster and generating more lift.&lt;/p&gt;&#xA;&lt;p&gt;However the aircraft in a rolled attitude actually slips into the turn and the dihedral effect tends to decrease the roll angle of the slipping aircraft (&lt;a href=&quot;http://avstop.com/ac/flighttrainghandbook/lateralstability.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;roll stability&lt;/a&gt;). So some degree of aileron deflection will be maintained.&lt;/p&gt;&#xA;&lt;p&gt;The ailerons (and the rudder) are used to return the wings to their horizontal position and stop the turn more accurately.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Ailerons-rudder coordination&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Coordinating turns is part of the basic training for a student pilot as uncoordinated turns are not only ineffective, they are also unsafe:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Some part of the wing or the controls can be in the shadow of the airflow, meaning they have no useful effect to control the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Lateral accelerations develop, the aircraft either &lt;a href=&quot;https://aviation.stackexchange.com/questions/77528/what-is-missing-from-these-diagrams-of-the-forces-in-slips-and-skids&quot;&gt;slips or skids&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The amount of rudder to apply can be determined using (human senses and) different instruments, including the &lt;a href=&quot;https://en.wikipedia.org/wiki/Turn_and_slip_indicator#Turn_coordinator&quot; rel=&quot;nofollow noreferrer&quot;&gt;turn coordinator&lt;/a&gt;, aka needle and ball Indicator, which is a sort of level (the ball) usually associated with a bank or rate of turn indicator (the needle). The respective position of the ball and the needle according to different uncoordinated/coordinated situations are like this:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VjQsM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VjQsM.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(&lt;a href=&quot;http://www.maxcraftavionics.com/Mid_Continent_Turn_Coordinator_12_32v_p/1394t100-7z.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j92iF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j92iF.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(&lt;a href=&quot;http://rcdictionary.blogspot.fr/2013/05/adverse-yaw.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;p&gt;When executing a coordinated level turn without wind, at sea level, etc, the radius of the turn and the turn rate depend only on the airspeed and the bank angle:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;TAS 150kt, bank 20°: Radius 1,676m, 360° in 2:16.&lt;/li&gt;&#xA;&lt;li&gt;TAS 300kt, bank 30°: Radius 4,227m, 360° in 3:51.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/2871/how-to-calculate-angular-velocity-and-radius-of-a-turn&quot;&gt;this question&lt;/a&gt; for additional information.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Yaw damper&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;In commercial airliners, the yaw control is assisted by one or two &lt;a href=&quot;https://en.wikipedia.org/wiki/Yaw_damper&quot; rel=&quot;nofollow noreferrer&quot;&gt;yaw damper(s)&lt;/a&gt; which function is to increase the yaw stability and prevent the development of the dangerous &lt;a href=&quot;https://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dutch roll&lt;/a&gt;. Thanks to the yaw dampers, the pilot does not need to use the rudder pedals for coordinated turns.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eFvmg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eFvmg.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;(&lt;a href=&quot;http://smithplanet.com/fs2004/pmdg/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Other means of controlling roll/lift&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;A mean of banking wings directly is required, including when Dutch roll and spin start developing and when flying or rolling with crosswind. But bank control can be obtained by other means than ailerons. While ailerons add lift by changing the camber of the wing,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Spoileron&quot; rel=&quot;nofollow noreferrer&quot;&gt;spoileron&lt;/a&gt;s combine spoilers and ailerons, and break lift by disturbing the laminar airflow (B-52),&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://books.google.com/books?id=y8anCwAAQBAJ&amp;amp;pg=PA18&amp;amp;lpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;rudderons&lt;/a&gt; combine rudder and ailerons on flying wings (B-2A),&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;and now bleed air and Coandă effect can bank the aircraft without moving surface (&lt;a href=&quot;https://www.cranfield.ac.uk/case-studies/research-case-studies/flaviir&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flaviir project&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-12-25T18:41:37.243" LastActivityDate="2020-12-25T18:41:37.243" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24103" PostTypeId="2" ParentId="24099" CreationDate="2016-01-02T23:45:39.690" Score="5" Body="&lt;p&gt;If you look closely at the example, it's describing a situation where you're cruising at 5500 feet, and landing at an airport with a &quot;pressure altitude&quot; (elevation) of 680 feet. The chart, however, is indexed to zero-altitude. You can't just reduce your cruise altitude by the elevation of the airport, because performance varies with altitude (indicated by the curvature of the arcs for fuel, time, and distance). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To find what you'd need to descend to the airport, you must run the numbers twice - once for descending to sea level from cruise (3 gallons, 9 minutes, 30 NM), and once for descending from the airport to sea level (1 gallon, 2 minutes, 4 NM). Note the two sets of dashed arrows on the chart, providing the two example calculations. You then subtract the numbers for the airport from the numbers for the cruise altitude, as you would hopefully not descend below the altitude of the airport!&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="136" LastEditDate="2016-01-03T01:26:49.217" LastActivityDate="2016-01-03T01:26:49.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24104" PostTypeId="2" ParentId="24092" CreationDate="2016-01-03T03:18:21.070" Score="3" Body="&lt;p&gt;I think it is used in the same meaning as the maximum effort takeoff/landing (similar to @mins comment above). Maximum effort takeoff is used to reduce the ground roll/obstacle clearance distance. Maximum effort landing (or assault landing, as it is called) is used to reduce the ground roll after landing. This is mostly used for military aircraft, which may have to operate from small, improvised forward air strips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is alluded to in the &lt;a href=&quot;http://www.rebay.at/fliegen/manuals/pa44_manual.pdf&quot; rel=&quot;nofollow&quot;&gt;PA-44-180 manual&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In certain short field takeoff efforts when the shortest possible ground roll and the greatest clearance distance over a 50 ft. obstacle is desired, a flap setting of 25° is recommended.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This can also be figured out from the charts themselves. For Pressure altitude of 680', OAT of 8$^{\circ}C$, 8kt headwind and 3430 lb TOW, the normal TO roll is 920', while the short filed effort TO roll is only 800'. For the same specifications, the total distance over a 50' barrier using normal procedures is 1750', while using short field effort, it reduces to 1280' (All figures from the manual).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see a C130J demonstrating max-effort TO and landing &lt;a href=&quot;http://fightersweep.com/807/inside-cockpit-c-130j-hercules/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-03T03:18:21.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24105" PostTypeId="2" ParentId="24097" CreationDate="2016-01-03T04:52:24.040" Score="16" Body="&lt;p&gt;Internal combustion gasoline engines need to have a constant air/fuel ratio of 14.7:1 for efficient combustion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air/fuel mixture by volume remains constant as we climb but the air/fuel mixture by weight does not. The carburetor only knows the volume of air passing through it, and because the weight of the air becomes less as we climb, the mixture becomes too rich at altitude. THAT is why we have to lean the mixture as we climb&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Leaning&quot; the mixture mixes less fuel with the air in order to keep the air/fuel ratio at a constant 14.7:1 ratio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even with a leaned mixture, as the air becomes less dense, less power is produced because less air and fuel enters the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Forcing additional air into the engine with a mechanical driven compressor (supercharger), or exhaust driven compressor(turbocharger), can restore normal sea level power to the engine.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At sea level, forcing additional air into the engine can also boost performance to more than is available in a &quot;normally aspirated&quot; engine. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-01-04T15:02:19.650" LastActivityDate="2016-01-04T15:02:19.650" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24106" PostTypeId="1" CreationDate="2016-01-03T06:57:50.970" Score="3" ViewCount="1780" Body="&lt;p&gt;To clarify, I'm an aviation enthusiast, not a pilot. I have a question for ATR pilots (or anyone with knowledge of the ATR systems). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While travelling on an ATR-72, about 15 mins after takeoff (and presumably at cruising altitude) I felt a very rapid deceleration - to the point I felt pressure on the seatbelt. At the same moment, I felt a sudden change in the air pressure. Checking my altimeter-measuring watch, I saw a reading of 760mb - well bellow the normal ~1000. No masks dropped, however. Several people in the cabin became upset and worried. I was sitting on the second row and, although I can't be certain behind the closed door, I'm pretty sure I heard a 'whoop whoop' alert from the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The journey continued without diversion or any emergency landing (frustratingly, no crew announcement either). I did notice that the air pressure remained bellow 800mb for the rest of the ~30min flight, beginning to rise only during descent. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering if anyone has a clue what might have happened. My best guess is some sort of engine trouble leading to bleed air problems, causing the plane to fly at a lower altitude (unpressurized) for the rest of the flight. But then again, is it normal procedure not to divert/return? I should mention that we had departed a large metropolitan airport headed for a regional one, so a return to the largest, better-equipped airport made more sense, I would think.&lt;/p&gt;&#xA;" OwnerUserId="12873" LastActivityDate="2016-01-03T06:57:50.970" Title="Engine(?) &amp; Pressurization Problem in ATR-72" Tags="&lt;engine&gt;&lt;cabin-pressure&gt;&lt;bleed-air&gt;&lt;atr-72&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-01-03T13:36:08.687" ContentLicense="CC BY-SA 3.0" />
  <row Id="24107" PostTypeId="1" CreationDate="2016-01-03T09:31:15.880" Score="14" ViewCount="14645" Body="&lt;p&gt;In clear weather, when do pilots disconnect the autopilot, if the plane is flying an ILS approach and the autopilot is in &quot;approach&quot; mode (tracking both localizer and glideslope)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would the answer differ significantly in different planes, for example Boeing 777 vs Airbus A320?&lt;/p&gt;&#xA;" OwnerUserId="12876" LastEditorDisplayName="user12485" LastEditDate="2016-01-03T10:40:37.543" LastActivityDate="2017-01-10T00:31:14.433" Title="When do pilots disconnect the autopilot on an ILS approach?" Tags="&lt;landing&gt;&lt;autopilot&gt;&lt;ils&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24109" PostTypeId="2" ParentId="24107" CreationDate="2016-01-03T13:20:47.483" Score="13" Body="&lt;p&gt;The decision to disconnect the autopilot is made by the pilot and can be made at any point as long as the operational limitations of the aircraft are satisfied (according to the type of ILS). The pilot also has to satisfy the applicable regulations and company SOPs (as @Sami already pointed out). Note that this depends on the pilot decision too- the pilot can fly the missed approach in autopilot if he decides so.&lt;/p&gt;&#xA;&lt;p&gt;Usually, the aircrafts have &lt;em&gt;minimum&lt;/em&gt; altitudes below which the autopilot has to be disconnected, which are given in the aircraft operating limitaions. For example, for &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;ved=0ahUKEwi58KWYxo3KAhXFPhQKHSd_A5IQFgghMAE&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3Da340-limitations.pdf&amp;amp;usg=AFQjCNHsLv3VYX90kpOUpWiB0J9E9yb3YA&amp;amp;bvm=bv.110151844,d.c2E&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Airbus A340&lt;/a&gt;,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system#ILS_categories&quot; rel=&quot;noreferrer&quot;&gt;CATEGORY II&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;If the crew performs an automatic approach without autoland, the autopilot must be disengaged no later than at 80 feet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwiGluvj2o3KAhXQB44KHYycAOAQFgggMAE&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DLimitations_(B777).pdf&amp;amp;usg=AFQjCNHj5Las3dSbdnR7bUw55-TGnnVZWw&amp;amp;bvm=bv.110151844,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;Boeing 777&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Autopilot/Flight Director System&lt;/p&gt;&#xA;&lt;p&gt;The autopilot must be disengaged before the airplane descends more than 50 feet below the MDA unless it is coupled to an ILS glideslope and localizer or in the go–around mode.&lt;/p&gt;&#xA;&lt;p&gt;Without LAND 2 or LAND 3 annunciated, the autopilot must be disengaged&#xA;below 200 feet AGL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwiPr_z13I3KAhUCCo4KHRb_DCwQFggbMAA&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3Dgeneric-boeing-b787-fcom-limitations.pdf&amp;amp;usg=AFQjCNGu4uZHZL4Y1b9urCqChxcePO41Bg&amp;amp;bvm=bv.110151844,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;Boeing 787&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Autopilot/Flight Director System&lt;/p&gt;&#xA;&lt;p&gt;Without LAND 2 or LAND 3 annunciated, the autopilot must be disengaged&#xA;below 100 feet AGL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As an example in GA aircraft, for &lt;a href=&quot;https://aviation.stackexchange.com/a/20782/9731&quot;&gt;Cessna C172 G1000&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The autopilot must be disengaged below 200 feet AGL during approach operations..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As you can see, there is not much difference.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-03T18:24:16.950" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24110" PostTypeId="2" ParentId="24051" CreationDate="2016-01-03T13:39:00.840" Score="5" Body="&lt;p&gt;The mechanical linkage from control column (aileron) only addresses one of the things that affect coordination, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw&quot; rel=&quot;noreferrer&quot;&gt;adverse yaw&lt;/a&gt;. It is the most significant one, but not the only. Other reasons you may need some rudder deflection in coordinated flight include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Compensating for &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;noreferrer&quot;&gt;P-factor&lt;/a&gt;. At high angle of attack (slow flight) the propeller blade going up sees a lower angle of attack than the propeller blade going down, creating asymmetry of thrust. The effect depends on engine power and speed, making it too complex to compensate by just mechanical linkages.&lt;/li&gt;&#xA;&lt;li&gt;The rotating propeller slipstream also creates asymmetrical force on the rudder, requiring compensation depending on engine power and speed.&lt;/li&gt;&#xA;&lt;li&gt;In tail-draggers, the propeller precession creates rather significant yawing moment as the tail lifts off that needs to be connected using rudder, otherwise the plane could &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_loop_(aviation)&quot; rel=&quot;noreferrer&quot;&gt;ground-loop&lt;/a&gt;. Tail-draggers generally require active control by rudder, because they are directionally unstable on the ground.&lt;/li&gt;&#xA;&lt;li&gt;In multi-engine aircraft, asymmetric thrust in the event of engine failure. For multi-engine aircraft this is the most significant yawing moment that the rudder must be able to compensate.&lt;/li&gt;&#xA;&lt;li&gt;And last but not least, rudder is needed to damp the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;noreferrer&quot;&gt;Dutch roll&lt;/a&gt;. I've never heard that mentioned as problem in utility aircraft, but it is a big problem for transport aircraft and a reason why they usually come with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Yaw_damper&quot; rel=&quot;noreferrer&quot;&gt;yaw damper&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The yaw damper is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Control_theory#Closed-loop_transfer_function&quot; rel=&quot;noreferrer&quot;&gt;feedback controller&lt;/a&gt; that monitors the lateral acceleration and other parameters (yaw and roll rate) and applies rudder to damp the dutch roll, and also to provide coordination to turns flown by autopilot where usually the autopilot directly commands the ailerons and rudder is left up the the yaw damper. So yes, providing coordination is possible, but not via simple mechanical linkages. And of course the rudder pedals still need to be there so &lt;em&gt;un&lt;/em&gt;coordinated flight is possible for any of the reasons already listed in Ron Beyer's answer.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-01-03T13:39:00.840" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24112" PostTypeId="2" ParentId="24097" CreationDate="2016-01-03T15:50:08.010" Score="0" Body="&lt;p&gt;Not only is a rich fuel mixture inefficient, if it is too rich there can be zero combustion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A long time ago in auto shop, the shop teacher demonstrated the effect of too much gas and not enough oxygen. He took a old coffee can and sprayed some gas in it, then covered it with the plastic lid, that had a small hole in it. Placed a match at the hole and the resulting small fire was about the size of a small candle flame. After some time (about a minute), the fire had burned enough fuel, the remaining fuel-air mixture was at the correct ratio, and they burned with a rapid little whoosh.&lt;/p&gt;&#xA;" OwnerUserId="12881" LastEditorUserId="3386" LastEditDate="2016-01-03T16:28:00.883" LastActivityDate="2016-01-03T16:28:00.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24113" PostTypeId="2" ParentId="24107" CreationDate="2016-01-03T17:30:44.713" Score="9" Body="&lt;p&gt;I am a B777 pilot; on approach I typically disconnect the Autopilot once visual contact is assured and I am inside the Final Approach fix. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is any chance of a possible missed approach, (especially with a complicated missed approach procedure) I will leave the AP on until there is virtually no chance of a missed approach due to weather or other conflicting aircraft on the runway or elsewhere.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the pilots I fly with tend to do the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On departure, we generally hand fly until about 10,000' to keep up our skills. If the departure procedure is complicated, we will ask for the AP on at 200' so there is no chance of messing up the departure procedure. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12720" LastEditDate="2016-01-04T16:06:07.980" LastActivityDate="2016-01-04T16:06:07.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24114" PostTypeId="1" AcceptedAnswerId="24118" CreationDate="2016-01-03T17:55:09.193" Score="17" ViewCount="5633" Body="&lt;p&gt;In the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_rudder_issues&quot;&gt;few rudder incidents&lt;/a&gt; with the B737, rudder-freeze caused the airplane to roll. From what I know, the rudder causes yaw while the aileron causes roll. Why in the case of these accidents/incidents would the rudder cause a roll?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="3386" LastEditDate="2016-02-15T13:09:44.067" LastActivityDate="2016-02-15T13:09:44.067" Title="Why does rudder cause roll?" Tags="&lt;boeing-737&gt;&lt;rudder&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24115" PostTypeId="1" AcceptedAnswerId="24126" CreationDate="2016-01-03T18:05:44.153" Score="11" ViewCount="3627" Body="&lt;p&gt;Early versions of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-134&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-134&lt;/a&gt; had a glass ('glazed') nose that is unusual for a passenger airliner. It was removed from the later versions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wBJR6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wBJR6.jpg&quot; alt=&quot;Tu-134 glass nose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/9/9d/Tu-134A_in_Ulyanovsk_Aircraft_Museum.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikimedia.org&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How probable is the hypothesis that this early design was for the easy conversion of Tu-134s into bomber? Glass noses are common in bombers.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="22726" LastEditDate="2019-01-24T04:01:21.940" LastActivityDate="2021-01-23T02:34:23.903" Title="Is the &quot;glass nose&quot; Tu-134 design for easier conversion to military use?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;military&gt;&lt;tu-134&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24116" PostTypeId="2" ParentId="24114" CreationDate="2016-01-03T18:20:07.850" Score="9" Body="&lt;p&gt;When an aircraft yaws, one wing travels faster than the other creating more lift on that side. On a swept wing aircraft the lifting effect is even more pronounced. The extra lift on one side will cause it to roll. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HPaq7.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HPaq7.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-01-03T18:20:07.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24117" PostTypeId="2" ParentId="24114" CreationDate="2016-01-03T18:27:24.603" Score="13" Body="&lt;p&gt;After stopping by at our physics friends, it's probably because of the swept wings (causing a lift differential) of the B737:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] if you introduce a yaw to the aircraft, one wing will extend out more directly into the wind-stream, while the other wing will be even more swept. This effectively makes one wing longer, and the other wing shorter. [...] The longer wing will generate more lift, and the shorter one will generate less lift. And since there is unequal lift around the roll axis, the airplane will roll, and continue to roll.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The whole answer: &#xA;&lt;a href=&quot;https://physics.stackexchange.com/a/49978&quot;&gt;Physics: What causes an aircraft to roll when rudder is applied&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note&lt;/strong&gt;: Regarding the comments, this effect even occurs without swept wings. Swept wings only amplify the effect.&lt;/p&gt;&#xA;" OwnerUserId="9290" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2016-01-05T08:51:12.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24118" PostTypeId="2" ParentId="24114" CreationDate="2016-01-03T18:37:07.370" Score="23" Body="&lt;p&gt;There are many higher-order effects. For example, yaw causes a slight increase in airspeed over the outer wing of the turn and a decrease in airspeed over the inner wing. As a result, the outer wing will generate more lift than the other, introducing a rolling motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yaw also causes side-slip which triggers several effects. Wings that are swept backwards, as on the B737, contribute to the roll towards the direction of the turn, because the outer wing gets effectively longer (&lt;a href=&quot;https://i.stack.imgur.com/HPaq7.gif&quot; rel=&quot;noreferrer&quot;&gt;visual explanation&lt;/a&gt;) and produces more lift. Further contributing to this roll is the outer wing having a higher angle of attack due to the dihedral effect (&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/d/df/SK_Dihedral_3.png&quot; rel=&quot;noreferrer&quot;&gt;visual explanation&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar effects apply to other control surfaces. It's not true that rudder only causes yaw and ailerons only cause roll. Those are simplifications, even though aircraft are usually designed for these simplifications to hold fairly well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also a direct effect. The image below didn't show the center of mass; I drew in a guess as a yellow circle. It's clearly below the rudder, which is true for most aircraft. This means applying rudder introduces a rolling torque, roughly equal to the sideways component of the force on the control surface, multiplied by the distance between rudder and the longitudinal axis. The magnitude of this product is visualised as the area of the red rectangle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ha4fN.png&quot; alt=&quot;B737 front view&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="67" LastEditorUserId="67" LastEditDate="2016-01-04T22:15:16.420" LastActivityDate="2016-01-04T22:15:16.420" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24119" PostTypeId="1" AcceptedAnswerId="24122" CreationDate="2016-01-03T18:57:25.207" Score="12" ViewCount="11247" Body="&lt;p&gt;Another question's &lt;a href=&quot;https://aviation.stackexchange.com/a/24109/7532&quot;&gt;answers&lt;/a&gt; refer to certain Boeing jets having the capability to annunciate &quot;Land 2&quot; and &quot;Land 3&quot; when flying a coupled ILS approach. What does each of these modes require, and allow, beyond the basic coupled ILS? How are they different from one another?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-06-22T11:47:08.637" Title="What is the difference between &quot;Land 2&quot; and &quot;Land 3&quot; annunciations for Boeing autopilot systems?" Tags="&lt;autopilot&gt;&lt;boeing&gt;&lt;approach&gt;&lt;ils&gt;&lt;autoland&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24120" PostTypeId="1" CreationDate="2016-01-03T19:01:16.900" Score="11" ViewCount="3214" Body="&lt;p&gt;Why is it that some wings are not painted on commercial jets? Couldn't they paint them the same color as the fuselage or would it be a waste of money?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="12720" LastEditDate="2016-01-04T01:06:27.593" LastActivityDate="2020-04-15T02:32:37.683" Title="Why are some airplane wings not painted?" Tags="&lt;paint&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24121" PostTypeId="1" CreationDate="2016-01-03T19:11:19.080" Score="24" ViewCount="689" Body="&lt;p&gt;I retired in 1999. I'm curious to what degree typical airline ops specs now discourage or prohibit doing what I used to do as a matter of course insofar as hand flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I usually hand flew the aircraft until leveling at the first cruise altitude (FL290 or FL310 on fully loaded 747-100/200 aircraft). For the step climbs as fuel was burnt, I nearly always disengaged the autopilot and did the climb manually. At the top of descent I clicked the autopilot off, and I flew approaches manually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of my fellow crew members thought it odd that I did so much hand flying, but as I would explain when asked, I didn't get to the 747 until I was 50 and didn't get to its left seat until a couple of years later, and I wasn't about to forego any of the fun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of the hand flying I did was prohibited by our ops specs of the time. My question is: to what degree, if any, do current ops specs discourage or prohibit the hand flying I did?&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2016-05-03T16:34:01.497" Title="To what degree do airline ops specs preclude hand flying?" Tags="&lt;airline-operations&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24122" PostTypeId="2" ParentId="24119" CreationDate="2016-01-03T19:13:06.903" Score="11" Body="&lt;p&gt;From &quot;Smart Cockpit&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smartcockpit.com/docs/B777-Automatic_Flight.pdf&quot; rel=&quot;noreferrer&quot;&gt;B777 Automatic Flight&lt;/a&gt; (PDF!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Lg5JZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lg5JZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;AFDS Status Annunciation&lt;/strong&gt;&lt;br&gt;&#xA;  The following AFDS status annunciations are displayed just above the PFD attitude display:&lt;br&gt;&#xA;   • FLT DIR (the flight director is ON and the autopilots are not engaged)&lt;br&gt;&#xA;   •   A/P (the autopilots are engaged)&lt;br&gt;&#xA;  •   LAND 3 (three autopilots are engaged and operating normally for an &#xA;  automatic landing)&lt;br&gt;&#xA;  •   LAND 2 (AFDS redundancy is reduced; in some cases, only two autopilots are available)&lt;br&gt;&#xA;  •   NO AUTOLAND (the AFDS is unable to make an automatic landing).&lt;br&gt;&lt;br&gt;&#xA;  With a LAND 3 indication, the autopilot system level of redundancy is such that a single fault cannot prevent the autopilot system from making an automatic landing (fail operational). &lt;br&gt;&lt;br&gt;&#xA;  With a LAND 2 indication, the level of redundancy is such that a single fault cannot cause a significant deviation from the flight path (fail passive).&lt;br&gt;&lt;br&gt;&#xA;  An EICAS message is displayed for any fault which limits the capability of the automatic landing system. Aural alerts for EICAS messages not affecting safety of flight are inhibited until after touchdown. Changes in autoland status below 200 feet, other than a transition to &#xA;  NO AUTOLAND status, are inhibited.&lt;br&gt;&#xA;  &lt;sup&gt;&lt;sub&gt;From Chapter 9, pages 22-23&lt;/sub&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="5517" LastEditDate="2016-01-07T17:21:58.523" LastActivityDate="2016-01-07T17:21:58.523" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24124" PostTypeId="2" ParentId="24120" CreationDate="2016-01-03T20:34:58.610" Score="7" Body="&lt;p&gt;Fuselage present a large vertical surface with greater length than height. Wings are a large horizontal surface that is shorter in the direction of travel. So...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage paint job is clearly visible on the ground, painting on the wings only if you are above or below the plane. This is probably the main reason. Simple geometry. It &lt;strong&gt;would&lt;/strong&gt; be waste of money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sun will heat a large horizontal surface more than a large vertical surface, so making the wings white is more useful than making the fuselage white. While I am not sure that wings would be structurally weaker if heated, the heat would cause thermal expansion, which would indirectly result in increased drag by making maintaining optimal shape more difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paint has significant effect on drag, more specifically it affects when the boundary layer transitions from laminar to turbulent. In the very long fuselage the difference is probably insignificant and you can paint them as you wish, but for wings the paint should be as smooth as you can make it. While I doubt white paint is smoother than paint of any other color, keeping it simple is probably a good idea.&lt;/p&gt;&#xA;" OwnerUserId="4472" LastActivityDate="2016-01-03T20:34:58.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24125" PostTypeId="2" ParentId="24121" CreationDate="2016-01-04T00:12:23.443" Score="13" Body="&lt;p&gt;There are no Ops Specs that preclude hand flying, however company policy and operational considerations do in specific situations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Level flight within RVSM airspace &lt;/li&gt;&#xA;&lt;li&gt;Cat III approaches (and I believe Cat II approaches) &lt;/li&gt;&#xA;&lt;li&gt;High workload, critical phases of flight (company specific policies here) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The FAA even came out with a &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2013/SAFO13002.pdf&quot; rel=&quot;nofollow&quot;&gt;SAFO&lt;/a&gt; not too long ago recommending that pilots do more hand flying during periods of low workload (and during training) with the goal of maintaining hand flying proficiency. &lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="755" LastEditorDisplayName="user12485" LastEditDate="2016-05-03T16:34:01.497" LastActivityDate="2016-05-03T16:34:01.497" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24126" PostTypeId="2" ParentId="24115" CreationDate="2016-01-04T00:31:26.920" Score="4" Body="&lt;p&gt;It's because of its lineage, based on military aircraft. The Tu-134 provided a glass nose for a navigator position, providing them with a clear view of the ground ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Tupolev Bureau, &lt;a href=&quot;http://www.tupolev.ru/en/civil_aviation/tu-134&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-134 is an upgrade of Tu-124&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tu-134 ... is an profound upgrade of Tu-124 with turbofan engines, arranged in the aft part of the fuselage. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NUHoW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NUHoW.jpg&quot; alt=&quot;Tu-124&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-124 from tupolev.ru&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-124, in its turn, &lt;a href=&quot;http://www.tupolev.ru/en/aircrafts/tu-124&quot; rel=&quot;nofollow noreferrer&quot;&gt;was based on the Tu-104&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1958, designing of such passenger plane was started in the Tupolev Design Bureau. Tupolev’s proposal for creation of a new short-range passenger aircraft on the basis of the common aerodynamic and structural layout of Tu-104 has been worked out ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jcLMl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jcLMl.jpg&quot; alt=&quot;Tu-104&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tu-104 from tupolev.ru&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In turn, Tu-104 was based on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-16&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-16 Badger&lt;/a&gt;, &lt;a href=&quot;http://www.tupolev.ru/en/aircrafts/tu-104&quot; rel=&quot;nofollow noreferrer&quot;&gt;which meant that it inherited the glazed nose&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the end of 1953, the Design Bureau’s leaders, headed by A.N. Tupolev, basing on the positive experience of developing, testing and beginning of serial production of Tu-16, proposed the idea of creating jet passenger aircraft on its basis to the leadership of the country. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On June 11, 1954 the Council of Ministers of the USSR issued a decree № 1172-516 on creation a long-range high-speed passenger aircraft designated Tu-16P .. . It was to be designed on the basis of Tu-16 airplane with two AM-3-200 engines.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Aknjn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Aknjn.jpg&quot; alt=&quot;Tu-16&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Tu-16.jpg#/media/File:Tu-16.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tu-16&lt;/a&gt;&quot; by No machine-readable author provided. &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Jno~commonswiki&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Jno~commonswiki&quot;&gt;Jno~commonswiki&lt;/a&gt; assumed (based on copyright claims). - No machine-readable source provided. Own work assumed (based on copyright claims).. Licensed under CC BY 2.5 via &lt;a href=&quot;https://commons.wikimedia.org/wiki/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The glazed nose had a practical purpose- the navigator sat there (the aircraft needed a crew of three). The later versions of Tu-134 (Tu-134B) on the other hand, did away with the glazed nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cVmvU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cVmvU.jpg&quot; alt=&quot;Tu-134&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tu-334, on the other hand, had a completely new design, eliminating the glazed nose.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1289" LastEditDate="2016-01-04T09:48:06.803" LastActivityDate="2016-01-04T09:48:06.803" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24127" PostTypeId="2" ParentId="24120" CreationDate="2016-01-04T01:16:47.723" Score="7" Body="&lt;p&gt;A number of aircraft manufacturers do paint the wings; only that the color is more neutral (like white or gray) rather than the flashy aircraft liveries as found in the fuselage and vertical tail. According to Boeing, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html&quot; rel=&quot;noreferrer&quot;&gt;the wings are indeed painted&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wing skins are made of bare aluminum and are protected by an impact-resistant paint system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Modern wings are composite and are protected by paint anyway:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Protective paint is used in certain areas to prevent corrosion, and it is used on all composites to prevent erosion and moisture ingress.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It appears that the &lt;a href=&quot;http://www.stts-group.com/home/about-us/&quot; rel=&quot;noreferrer&quot;&gt;wings of Airbus aircraft are also painted&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... operate within the Airbus UK wing production facility, painting all narrow-body wing sets.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for painting in airline livery, it would add another coat of paint, adding weight (For example, paint in A380 weighs half a ton already). Not a lot of people is going to see the wing paint anyway.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-04T01:16:47.723" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24128" PostTypeId="1" AcceptedAnswerId="24129" CreationDate="2016-01-04T02:08:05.107" Score="6" ViewCount="784" Body="&lt;p&gt;Please take a look at the MIA5 depatarture from KOPF:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://155.178.201.160/d-tpp/1513/00256MIAMI.PDF&quot; rel=&quot;nofollow&quot;&gt;MIA5 Page 1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://155.178.201.160/d-tpp/1513/00256MIAMI_C.PDF&quot; rel=&quot;nofollow&quot;&gt;MIA5 Page 2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instructions seem in conflict. Specifically, suppose you are taking off RW 270R and want the WINCO transition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The textual instructions are:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;climb heading 273°, thence.... &lt;/li&gt;&#xA;&lt;li&gt;....maintain 2000 or higher altitude&#xA;and expect vectors to appropriate transition. Expect further&#xA;clearance to filed altitude 10 minutes after departure.   &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;OK - that&#xA;    is straightforward essentially runway heading to vectors to WINCO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there is a third text segment on page 2 regarding the WINCO transition:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;From over DHP VORTAC on DHP R-322 to WINCO INT&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DHP is a &lt;strong&gt;LEFT&lt;/strong&gt; turn from OPF and would take the airplane directly across the KMIA departure / arrival paths; WINCO is a right turn. Which is it? What do I do in lost comm? Why do they have &quot;from over DHP&quot; I would expect the instruction to be &quot;climb heading 273° to intercept DHP R-322 to WINCO&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if I load that procedure into Garmin Pilot, it just shows a path direct from OPF to DHP then to WINCO which I know is wrong.&lt;/p&gt;&#xA;" OwnerUserId="2072" LastEditorUserId="7532" LastEditDate="2017-01-05T02:03:44.253" LastActivityDate="2017-01-05T02:03:44.253" Title="DP confusion. Do I turn left or right if not told?" Tags="&lt;air-traffic-control&gt;&lt;faa&gt;&lt;departure-sid&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24129" PostTypeId="2" ParentId="24128" CreationDate="2016-01-04T03:42:00.093" Score="7" Body="&lt;p&gt;The ROUTING is DHP 322 radial to WINCO.  So that's the course line that you'd intercept when so instructed.  There is no reason to actually start at DHP, and since you'll be flying the heading off the runway, the leg from the field to DHP in the Garmin is immaterial.  You can expect that they'll either clear you to WINCO, or (for a non-RNAV aircraft, most likely)  that they'll clear you on a heading to intercept the DHP 322 radial to WINCO (and thence as filed), so you'd cycle the active leg from the {OPF to DHP} leg, to the next leg, which is {DHP to WINCO} (which is the same as the DHP 322 radial), and then you'd intercept that active leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nothing in those instructions is telling you to fly to DHP, nor should you expect that you'd get a clearance to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the question in the title, &lt;strong&gt;until you're told otherwise, you fly the initial heading in the text instructions.  You're on vectors, so don't turn until told to do so.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you go lost comm, then &lt;strong&gt;AVE-F&lt;/strong&gt; would tell you that you're on &lt;strong&gt;V&lt;/strong&gt;ectors to WINCO, so get yourself there as best you can, probably by turning direct if you're RNAV equipped, or flying the radial if not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Note, though, that in the normal (with comm) case,the DP instruction is NOT to fly heading 273 to intercept the radial; it is to fly that heading.  That's your only CLEARANCE.  ATC will turn you to intercept on whatever heading they want you on.  &lt;strong&gt;Only&lt;/strong&gt; in the case of lost comm would you turn to WINCO upon reaching the 322 radial.  In all other cases, follow ATC instructions.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-01-04T03:57:01.500" LastActivityDate="2016-01-04T03:57:01.500" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24130" PostTypeId="2" ParentId="22371" CreationDate="2016-01-04T12:12:22.593" Score="3" Body="&lt;p&gt;Okay so there are a few points to this&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Lots of different things are sold - perfumes etc, gifts, &quot;in flight&quot; convenience items such as headphones, plus food/drink. That means lots of sales opportunities.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;Luxury&quot; items are high margin anyway: perfume is a big profit item even with duty. By knocking the duty off and making it &quot;feel&quot; cheap: they can potentially sell it for &lt;strong&gt;more&lt;/strong&gt; than the RRP (minus duty), and thus make more profit than a regular shop, despite selling it for less (gross) to the passenger&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You only need to carry one or two bottles of each perfume, as you won't sell a ton of them. They don't take up much space: perfumes etc are only sold to one or two people per flight, they're not the reason the cart is there... they're just an extra. Similarly headphones: you won't sell many, but you'll definitely sell some when somebody realises they left theirs at home: I bought a set of cheapo £2 headphones for £8 at a train station a few days ago because wasting £6 on a set of crappy headphones was better than the idea of a 5 hour train without any music. People will pay for convenience, and carrying one or two of these items doesn't take up much space at all.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Food/drink are the reason the cart is there. When on a flight for 1-4 hours, some people are going to be hungry/thirsty... and you have anywhere from 100 to 850 passengers. The markup on these items can be huge - £6 for a small can of beer, for example, which would cost &amp;lt;£0.30 from a wholesaler. You don't need to sell a huge number of pies/burgers/cans of beer/£3 cans of coke to make a decent profit. With the air-con on a plane, I find I get very thirsty and will go through a 500ml drink roughly once an hour. Similarly on a 4+ hour flight I'll tend to want a snack or meal at some stage. I'm certainly not alone in this.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Seats on these planes aren't always that expensive. On my last flight it was less than £40 for my one-way ticket on a 2 hour flight: if the trolley takes up roughly one seat's worth of space, they only need £40 in profit (or perhaps 20 cans of coke in 2 hours, at £2.50 per can) to be worth carrying a trolley. Similarly the longer the flight, the more likely people are going to be thirsty. With 190 people on board, even if only one in 10 buys a drink, that trolley has made more profit than my seat. Even considering an 8 hour transatlantic flight with 400 people on board a 767, that still only needs half the flight to buy one drink (which they probably will in 8 hours...) to make up for my £500 seat&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It's expected, and is a service to some extent... people would start getting quite annoyed if they found they couldn't get a drink on the flight, even if said drink is expensive. People tend to expect to be able to get a drink, if nothing else, but usually food too. Notice that most non-local (2hr+) trains (and many local ones!) tend to have a trolley service or, more and more often, a shop on board? Even if it didn't make a profit at all, it may be worthwhile for customer happiness. This is a bit of a moot point, though, as trolley services are definitely profitable (trust me, if it wasn't, Ryanair wouldn't provide one)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Your cabin crew are there anyway for safety reasons, why not put them to use as sales people? Otherwise they're just sitting relatively idle for much of the flight. Not that I wish to discredit the work and important role that cabin crew play: they're far more important than most of us realise... but the fact remains that for much of the middle of the flight, on a routine flight and unless something goes wrong, they don't actually necessarily have that much to do considering the number carried.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The cart may be there anyway! On longer flights with meal services, the airline will already have the cart available for set times. Why not put a few bottles of perfume in the bottom for an extra profit?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Capacity limits. Aircraft aren't always limited purely by space or weight: they're also only certified to carry a set number of passengers due to things like the number of emergency exits. It may be that you can't actually carry more passengers even if you want to&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The trolley can fit into space a person wouldn't. A trolley isn't person shaped, and can be stored somewhere near the back of the plane (eg where the fuselage tapers) that you couldn't fit another seat even if you wanted to. Why not use the space for something useful?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-01-04T12:12:22.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24131" PostTypeId="2" ParentId="8786" CreationDate="2016-01-04T14:17:29.310" Score="7" Body="&lt;p&gt;Its not just fighter planes that have the stick in the right and power in the left. That's the way tandem (front-and-back seating) aircraft are set up in general. You can see the throttle on the left-hand wall in this Citabria:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EzuTi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EzuTi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And gliders and helicopters are also set up with &quot;the stick&quot; in the right hand and &quot;power&quot; in the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though a glider doesn't have an engine, most of them have some kind of airbrakes, which are deployed just as if it was a throttle. Pushing the lever forward with the left hand decreases drag and pulling backwards increases drag. This isn't the same as thrust, but to a power pilot, it feels fairly natural to push forward to go faster and pull backwards to go slower. The speed brake handle in this glider is the blue handle on the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sd0cF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sd0cF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a helicopter, the right hand (no matter which side the pilot sits on) is for the cyclic, which (for the post part) controls pitch and roll, and the left hand controls the collective and throttle, which together work to add and remove power from the aircraft. This also feels fairly natural to pilots who are used to stick in the right, throttle in the left. The big difference is that the collective is an &quot;up/down&quot; control like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Johnson_bar_(vehicle)&quot; rel=&quot;noreferrer&quot;&gt;Johnson bar&lt;/a&gt;, not a &quot;forward/back&quot; control, and you put it down to reduce power and up to increase power. Furthermore, the throttle, when manually controlled, is a twist grip on the collective, which operates more like a motorcycle throttle.  You can see the heli controls in this simulator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2uJDg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2uJDg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-04T14:23:55.887" LastActivityDate="2016-01-04T14:23:55.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24132" PostTypeId="2" ParentId="24121" CreationDate="2016-01-04T15:31:57.987" Score="12" Body="&lt;p&gt;My company only mandated autopilot use during monitored approaches (all cat II approaches and cat I below RVR 2400 for high minimums captains) and for compliance with RVSM ops.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I typically hand flew at least up to 10,000 feet but often up into the flight levels.  On descent into fields with a lot of vectoring I usually disconnected the autopilot on our final vector to intercept the approach.  Going into less busy places I often disconnected the autopilot when descending out of 10,000 feet.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also tried to get in one raw-data (no autopilot, no flight director) ILS approach every trip I flew to keep those skills up.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-04T15:31:57.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24133" PostTypeId="1" AcceptedAnswerId="24264" CreationDate="2016-01-04T15:36:38.323" Score="8" ViewCount="14055" Body="&lt;p&gt;I am trying to understand the &lt;a href=&quot;https://en.wikipedia.org/wiki/Horizontal_situation_indicator&quot;&gt;Horizontal Situation Indicator&lt;/a&gt;. To my understanding there is a slaving transmitter, usually in a wing (the left wing in the Piper Archer and Seminole), which sends information to a flux gate, which then sends information to the compass card in a slaved HSI. Is any of that correct? Are the slaving transmitter and the flux gate separate components?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-01-04T15:43:43.230" LastActivityDate="2020-05-02T12:30:24.313" Title="How does a horizontal situation indicator (HSI) work?" Tags="&lt;flight-instruments&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24134" PostTypeId="2" ParentId="24115" CreationDate="2016-01-04T15:43:45.180" Score="9" Body="&lt;p&gt;Converting a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-104&quot; rel=&quot;noreferrer&quot;&gt;Tu-104&lt;/a&gt;, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-124&quot; rel=&quot;noreferrer&quot;&gt;Tu-124&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-134&quot; rel=&quot;noreferrer&quot;&gt;Tu-134&lt;/a&gt; to a bomber only would had worked if there had also been provisions for a bomb bay. Including this in a pressurized fuselage would had incurred a severe weight penalty, so there was no easy way for a bomber conversion. This should make the speculation about dual use as a bomber moot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are several good reasons to use the glazed nose:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Easier conversion of trained bomber crews (trained on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Ilyushin_Il-28&quot; rel=&quot;noreferrer&quot;&gt;Il-28&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-16&quot; rel=&quot;noreferrer&quot;&gt;Tu-16&lt;/a&gt;) for civilian duties. Remember that the Tu-104 was the second jet airliner in service and the only operational jet airliner worldwide between 1956 and 1958.&lt;/li&gt;&#xA;&lt;li&gt;Operation as a military transport on improvised flights (where the better view of the navigator in the nose would help in visual navigation).&lt;/li&gt;&#xA;&lt;li&gt;Civilian operation on flights on routes without navigation aids.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The last point is added by @JanHudec as a comment to &lt;a href=&quot;https://aviation.stackexchange.com/questions/24115/is-the-glass-nose-tu-134-design-for-easier-conversion-to-military-use/24126?s=1%7C0.2451#24126&quot;&gt;this answer&lt;/a&gt;, but would exclude the operation on a scheduled service, because the aircraft would not be able to navigate in fog or at night.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the glazed nose was removed quite early in the production run of the Tu-134 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-134#Variants&quot; rel=&quot;noreferrer&quot;&gt;from the A-2 version on&lt;/a&gt;), it seems that the first reason (dual use of Tu-16-trained crews) is the most likely. While more than 1,500 Tu-16s were built, the Tu-104 (201 built from 1956 to 1960) and Tu-124 (164 built from 1960 to 1965) were relatively rare. From the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-104&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia page on the Tu-104&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots with previous Tu-16 experience transitioned into the Tu-104&#xA;  with relative ease&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-04T15:43:45.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24135" PostTypeId="2" ParentId="24114" CreationDate="2016-01-04T16:13:12.907" Score="13" Body="&lt;p&gt;The reasons can be split in two categories: Direct and indirect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Direct reasons are rolling moments which are created directly due to the rudder deflection and the side force on the vertical tail:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Offset position of the vertical tail:&lt;/strong&gt; Since the rudder is above the longitudinal axis of inertia, a side force will also cause a rolling moment. This is the main reason for the anhedral of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-104&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Once the yawing motion starts, the forward-moving wing experiences a slight increase in dynamic pressure, so lift is increased on the forward moving wing and vice versa. This effect is inverse to flight speed and small in general.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Indirect reasons are caused by the resulting sideslip angle once the aircraft starts to yaw:&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;strong&gt;Dihedral:&lt;/strong&gt; Once the rudder-caused yaw produces a sideslip angle, the relative difference in angle of attack between both wings creates a rolling moment. This is proportional to the dihedral angle &lt;strong&gt;in flight&lt;/strong&gt;, so you need to add wing bending to a static view of the aircraft to get an idea of the effective dihedral angle.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Wing position:&lt;/strong&gt; On a high wing, the changed flow around the fuselage in sideslip will create a &lt;a href=&quot;https://aviation.stackexchange.com/questions/12099/why-do-low-wing-aircraft-have-higher-dihedral-than-high-wing-aircraft/12101#12101&quot;&gt;difference in angle of attack&lt;/a&gt; at the root of the wing. This effect needs to be considered when selecting the proper dihedral angle; therefore &lt;a href=&quot;https://aviation.stackexchange.com/questions/6285/why-does-an-225-have-anhedral-wings-though-it-is-a-cargo-aircraft?s=1%7C1.4349&quot;&gt;high-wing aircraft have less dihedral&lt;/a&gt; than low-wing aircraft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Wing sweep:&lt;/strong&gt; The reduced sweep angle of the windward wing will increase its lift curve slope, and the reverse happens on the opposite wing. This creates a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292#9292&quot;&gt;strong rolling moment&lt;/a&gt; which is proportional to the sweep angle.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Once the sideslip angle increases, the rudder-induced side force will decrease until the aircraft reaches the trim point where the sideslip angle fully cancels the rudder deflection. But the aircraft is still yawing, so it will exceed the trim position and now the side force will act in the opposite direction. Proportionally to the side force, the tail-induced rolling moment will also change due to the buildup in sideslip.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-01-09T03:10:08.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24136" PostTypeId="1" AcceptedAnswerId="24137" CreationDate="2016-01-04T16:15:01.713" Score="7" ViewCount="4209" Body="&lt;p&gt;For flight operations conducted under 14 CFR part 91(other than subpart F) in VMC, what conditions constitute &quot;known icing conditions&quot;? Under what circumstances (e.g., altitude difference or no visible moisture), if any, could a VFR flight operation (other than in an aircraft certified for flight into known icing) be legally conducted despite an Area Forecast, AIRMET Zulu, Pirep or other possible indicator of known icing conditions?&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-05T11:59:23.877" LastActivityDate="2016-01-05T11:59:23.877" Title="What constitute &quot;known icing conditions&quot; and when can you fly VFR while they exist?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;flight-planning&gt;&lt;visual-flight-rules&gt;&lt;icing&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24137" PostTypeId="2" ParentId="24136" CreationDate="2016-01-04T16:53:35.747" Score="5" Body="&lt;p&gt;The short answer is that it's up to you as PIC to make that determination; the FAA has no clear definition apart from what a &quot;reasonable and prudent&quot; pilot would do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA issued &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/bell%20-%20%282009%29%20legal%20interpretation.pdf&quot;&gt;a legal interpretation&lt;/a&gt; on exactly this question in 2009, here's the closest thing to a definition that they give (my emphasis throughout):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&quot;Known icing conditions&quot; involve instead circumstances where a&#xA;  reasonable pilot would expect a substantial likelihood of ice&#xA;  formation on the aircraft based upon all information available to that&#xA;  pilot&lt;/strong&gt;. While &quot;known icing conditions&quot; are not defined by regulation,&#xA;  the term has been used in legal proceedings involving violations of&#xA;  FAA safety regulations that relate to in- flight icing. The National&#xA;  Transportation Safety Board (NTSB) has held on a number of occasions&#xA;  that known icing conditions exist when a pilot knows or reasonably&#xA;  should know about weather reports in which icing conditions are&#xA;  reported or forecast&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They go on to say that the PIC is responsible for determining the likelihood of icing conditions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Any assessment of known icing conditions is necessarily fact-specific.&#xA;  Permutations on the type, combination, and strength of meteorological&#xA;  elements that signify or negate the presence of known icing conditions&#xA;  are too numerous to describe exhaustively in this letter. &lt;strong&gt;Whether a&#xA;  pilot has operated into known icing conditions contrary to any&#xA;  limitation will depend upon the total information available to the&#xA;  pilot, and his or her proper analysis of that information&lt;/strong&gt; in&#xA;  evaluating the risk of encountering known icing conditions during a&#xA;  particular operation. The pilot should consider factors such as the&#xA;  route of flight, flight altitude, and time of flight when making such&#xA;  an evaluation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that even visible moisture and freezing temps aren't automatically considered to be known icing conditions:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA does not necessarily consider the mere presence of clouds&#xA;  (which may only contain ice crystals) or other forms of visible&#xA;  moisture at temperatures at or below freezing to be conducive to the&#xA;  formation of known ice or to constitute known icing conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The specific regulations mentioned in the interpretation are 14 CFR 91.9 (compliance with the operating manual), 91.13 (no careless or reckless operation) and 91.103 (become familiar with all information relevant to the flight). Those regulations would be the basis for any hypothetical enforcement action:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;If the composite information indicates to a reasonable and prudent&#xA;  pilot that he or she will be operating the aircraft under conditions&#xA;  that will cause ice to adhere to the aircraft along the proposed route&#xA;  and altitude of flight, then known icing conditions likely exist.&lt;/strong&gt; If&#xA;  the pilot operates the aircraft in known icing conditions contrary to&#xA;  the requirements of § 91.9(a), the FAA may take enforcement action.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the bottom line is: you're PIC and it's your decision whether it's safe to fly or not because there are far too many variables for anyone else to decide. But personally I think it would be difficult for any pilot to say that it was &quot;reasonable and prudent&quot; to fly a non-FIKI aircraft in an area where forecasts, AIRMETs or PIREPS indicated icing.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-01-04T16:53:35.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24138" PostTypeId="1" AcceptedAnswerId="24144" CreationDate="2016-01-04T18:16:18.750" Score="6" ViewCount="797" Body="&lt;p&gt;Are all  US airline aircraft certified for flying into known icing (FIKI) conditions? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume all the large (100+ PAX) aircraft come FIKI certified from the design stage? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the largest passenger aircraft that would be non-FIKI certified? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="167" LastEditDate="2016-01-04T23:13:40.660" LastActivityDate="2016-01-04T23:13:40.660" Title="Are all US airline aircraft certified into known ice?" Tags="&lt;faa-regulations&gt;&lt;airliner&gt;&lt;airline-operations&gt;&lt;aircraft-certification&gt;&lt;icing&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24139" PostTypeId="1" AcceptedAnswerId="24142" CreationDate="2016-01-04T18:22:39.253" Score="6" ViewCount="884" Body="&lt;p&gt;What happens to the unused food after a flight? Does it get all destroyed (on-site or off-site) or is there some alternative use (e.g. Charity ) that it gets put to. Does the incoming food truck cart it off with the carts or is it handled by the Janitorial / Clean Up crews. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On shorter sectors can some items be used on the next flight with the carts only being &quot;topped up&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. Obviously, I'm referring to the perishable items with short shelf lives. Not talking about peanuts and other packaged items that last with longer shelf lives.  &lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2016-01-04T19:16:38.853" Title="Destiny of Unused food after flight" Tags="&lt;airline-operations&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ClosedDate="2016-01-04T23:14:02.420" ContentLicense="CC BY-SA 3.0" />
  <row Id="24140" PostTypeId="2" ParentId="24139" CreationDate="2016-01-04T18:50:20.750" Score="1" Body="&lt;p&gt;I will say about airlines in Brazil.&#xA;The meals that are not eaten by passengers, after the flight, they are loaded off by the catering service responsible for this, and they are tossed.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="12207" LastEditDate="2016-01-04T19:16:38.853" LastActivityDate="2016-01-04T19:16:38.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24141" PostTypeId="1" CreationDate="2016-01-04T18:56:31.803" Score="2" ViewCount="4248" Body="&lt;p&gt;Is there a specific reason why in most fighter planes, the control column is between the pilots legs instead of on the sides like Airbus airliners? I know the F-16 has sidesticks, but most of the others have it in the middle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/H35ib.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H35ib.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt; &#xA;F-16 Cockpit with sidestick&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y9nrQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y9nrQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;F-15 with centerstick&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Images from Wikipedia&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-01-04T20:07:06.187" LastActivityDate="2016-01-05T00:39:14.073" Title="Why do most fighter craft have a center stick?" Tags="&lt;aircraft-design&gt;&lt;military&gt;" AnswerCount="1" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24142" PostTypeId="2" ParentId="24139" CreationDate="2016-01-04T19:04:52.993" Score="8" Body="&lt;p&gt;The crew eats the food, no doubt. Just joking. The unused food is off loaded from the airplane into catering trucks and is discarded. It seems a bit sad but the reality is, any food that is leftover from a flight is considered “contaminated” so is discarded. This includes meals that passengers didn’t finish as well as entire carts full of food that were never used.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So what is being done to help eliminate unnecessary waste? With&#xA;  limited space on flights, some airlines have started to make small&#xA;  changes by only loading 95% of the required meals on each flight with&#xA;  the expectation that some passengers will opt not to eat. Other&#xA;  airlines have started charging around $10 a meal, recognizing that&#xA;  less food is consumed when meals are only available for purchase&#xA;  rather then complimentary. In the past, some airlines have even&#xA;  donated their unused food to shelters and charities to help make a&#xA;  difference. Unfortunately due to incidents where food poisoning&#xA;  occurred, the liability became much too high and is no longer&#xA;  practiced by airlines. &lt;a href=&quot;http://airportlifestyle.com/airplane-food/&quot;&gt;(Source)&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user10079" LastActivityDate="2016-01-04T19:04:52.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24143" PostTypeId="1" CreationDate="2016-01-04T19:25:38.690" Score="2" ViewCount="283" Body="&lt;p&gt;Landing on unpaved runways or runways covered by snow or dust causes a white/brown-out visibility restriction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it disrupt the pilot's visibility during the roll out in a fixed-wing aircraft?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="14897" LastEditDate="2016-06-21T22:46:22.143" LastActivityDate="2016-07-21T23:38:30.063" Title="Is white/brown-out effect hazardous during the landing roll out?" Tags="&lt;landing&gt;&lt;runways&gt;&lt;visibility&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24144" PostTypeId="2" ParentId="24138" CreationDate="2016-01-04T19:59:53.300" Score="10" Body="&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2b5931a55a0c902388f908e89459493f&amp;amp;mc=true&amp;amp;node=se14.3.121_1321&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;Title 14 CFR part 121.321&lt;/a&gt; regulates scheduled airline operations in icing conditions.  It requires airframe ice protection systems in order to operate in &amp;quot;conditions conductive to airframe icing&amp;quot;, which they define as:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;visible moisture at or below a static air temperature of 5 °C or a total air temperature of 10 °C, unless the approved Airplane Flight Manual provides another definition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This essentially means that any airline that can operate in IMC is going to be subject to this requirement unless they have very niche operations at low altitudes in warm lattitudes where they can stay below the 10 C level when in IMC.&lt;/p&gt;&#xA;&lt;p&gt;Aircraft operated by airlines that operate in IMC at temperatures colder than 10 C must either have an ice detection system or a means of detecting the first formation of ice on the airframe and then activate ice protection systems or they must, in the absence of detection, always operate their ice protection when operation in conditions conductive to airframe icing.&lt;/p&gt;&#xA;&lt;p&gt;For smaller on-demand operations operating under part 135, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=464db5b2f04c63329a3c111a9ce5f76c&amp;amp;mc=true&amp;amp;node=se14.3.135_1227&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.227&lt;/a&gt; regulates flight into icing conditions.  This regulation requires that any airplance flying into forecast icing (IFR only) or known icing conditions (VFR or IFR) has functioning de-ice or anti-ice protection.  This means a 135 operation ferrying passengers from Miami into the Bahamas probably doesn't have to worry about this, but a IFR 135 operation anywhere it gets cold probably does.&lt;/p&gt;&#xA;&lt;p&gt;For non-121 and non-135 operations in airplanes with 20 passenger seats or more, the applicable regulation is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=464db5b2f04c63329a3c111a9ce5f76c&amp;amp;mc=true&amp;amp;node=se14.3.125_1221&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 125.221&lt;/a&gt; and reads exactly like the part 135 regulation.&lt;/p&gt;&#xA;&lt;h3&gt;Summary&lt;/h3&gt;&#xA;&lt;p&gt;Combined, parts 121, 125 and 135 regulate the majority of commercial operations.   The requirements of part 121 realistically mean that any airplane suitable for scheduled airline operations is equipped with ice protection.  Part 135 can utilize a broader range of aircraft and while ice protection is not required it is quite limiting for the operation if it is not present (no flight into known or forecast icing conditions under IFR).&lt;/p&gt;&#xA;&lt;p&gt;This means that all airline aircraft (part 121) are certified for FIKI but not all passenger airplanes (operated under part 125 or 135) are certified for FIKI (and cannot operate in those conditions if not equipped).&lt;/p&gt;&#xA;&lt;h3&gt;Regs&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§121.321   Operations in icing.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) When operating in conditions conducive to airframe icing, compliance must be shown with paragraph (a)(1), or (2), or (3) of this section.&lt;/p&gt;&#xA;&lt;p&gt;(1) The airplane must be equipped with a certificated primary airframe ice detection system.&lt;/p&gt;&#xA;&lt;p&gt;(i) The airframe ice protection system must be activated automatically, or manually by the flightcrew, when the primary ice detection system indicates activation is necessary.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(2) Visual cues of the first sign of ice formation anywhere on the airplane and a certificated advisory airframe ice detection system must be provided.&lt;/p&gt;&#xA;&lt;p&gt;(i) The airframe ice protection system must be activated when any of the visual cues are observed or when the advisory airframe ice detection system indicates activation is necessary, whichever occurs first.&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(3) If the airplane is not equipped to comply with the provisions of paragraph (a)(1) or (2) of this section, then the following apply:&lt;/p&gt;&#xA;&lt;p&gt;(i) When operating in conditions conducive to airframe icing, the airframe ice protection system must be activated prior to, and operated during, the following phases of flight:&lt;/p&gt;&#xA;&lt;p&gt;...&lt;/p&gt;&#xA;&lt;p&gt;(ii) During any other phase of flight, the airframe ice protection system must be activated and operated at the first sign of ice formation anywhere on the airplane, unless the Airplane Flight Manual specifies that the airframe ice protection system should not be used or provides other operational instructions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§135.227   Icing conditions: Operating limitations.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(c) No pilot may fly under IFR into known or forecast light or moderate icing conditions or under VFR into known light or moderate icing conditions, unless—&lt;/p&gt;&#xA;&lt;p&gt;(1) The aircraft has functioning deicing or anti-icing equipment protecting each rotor blade, propeller, windshield, wing, stabilizing or control surface, and each airspeed, altimeter, rate of climb, or flight attitude instrument system;&lt;/p&gt;&#xA;&lt;p&gt;(2) The airplane has ice protection provisions that meet section 34 of appendix A of this part; or&lt;/p&gt;&#xA;&lt;p&gt;(3) The airplane meets transport category airplane type certification provisions, including the requirements for certification for flight in icing conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-04T19:59:53.300" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24145" PostTypeId="1" AcceptedAnswerId="24149" CreationDate="2016-01-04T20:52:35.057" Score="8" ViewCount="1522" Body="&lt;p&gt;What are the primary methods used to detect ice on an airframe, and how do they work on at least a high level?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2016-01-04T21:29:19.890" Title="What methods exist to detect airframe icing, and how do they work?" Tags="&lt;airframe&gt;&lt;icing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24146" PostTypeId="1" AcceptedAnswerId="24150" CreationDate="2016-01-04T20:54:27.020" Score="15" ViewCount="5225" Body="&lt;p&gt;I'm sure it's possible to use servo motors to get precise control of the ailerons, elevators or the rudder. But still, hydraulics are widely used instead. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hydraulics do have a disadvantage that a damage to the hydraulic pipes can cause loss of control. Even with redundancy, there are cases where all three hydraulic lines get damaged at the same time and there's complete loss of control (can't remember the example). I think in some smaller aircrafts servo motors are used. But why not in the larger ones. Is it because of the torque required? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the issues with using electric motors?&#xA;If used what are the safety concerns?&#xA;In terms of safety, how different are they from hydraulics?&lt;/p&gt;&#xA;" OwnerUserId="7213" LastEditorUserId="7213" LastEditDate="2019-05-15T10:13:09.140" LastActivityDate="2019-08-13T12:31:34.023" Title="Why do most commercial airplanes use hydraulics instead of electric/servo motors?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;aircraft-systems&gt;&lt;hydraulic-system&gt;" AnswerCount="6" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="24148" PostTypeId="2" ParentId="24146" CreationDate="2016-01-04T21:06:17.270" Score="2" Body="&lt;p&gt;Planes use hydraulics because of the immense pressures on the control surfaces during flight. Hydraulic systems can deal with higher loads than motors of similar size. An electric motor can get &quot;stuck&quot; when it encounters a load that is greater than it can move, possibly causing a crash if it happened in an airplane.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-04T21:06:17.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24149" PostTypeId="2" ParentId="24145" CreationDate="2016-01-04T21:09:30.730" Score="6" Body="&lt;p&gt;There are a few ways to sense ice on an airframe. The &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a266273.pdf&quot;&gt;DOT has a document&lt;/a&gt; here that outlines the various types of sensors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First and foremost planes have ice lights that project onto the wings so they can be visually inspected. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;https://en.wikipedia.org/wiki/Ice_detector&quot;&gt;completely optical sensors&lt;/a&gt; that use a variety of methods to detect ice.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also some electro mechanical devices, here are a few examples, the rest are outlined in the &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a266273.pdf&quot;&gt;DOT document&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Penny and Giles&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Penny and Giles system uses a probe type sensor that measures ice&#xA;  buildup in terms of Liquid Water Content (LWC). This system was&#xA;  designed specifically for use on helicopters and is available for all&#xA;  turbine-powered helicopters.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Rosemount&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The sensing probe is driven magnetostrictively to vibrate at its&#xA;  resonant frequency of 40,000 Hz. As the ice detector enters an icing&#xA;  environment, ice collects on the sensing probe. The added mass of the&#xA;  accreted ice causes the frequency of the sensing probe to decrease in&#xA;  accordance with the laws of classical mechanics.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Sunstrand&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The Sunstrand system uses a mounted probe with a sensing surface&#xA;  facing the airstream. Beta particles are released from a Strontium 90&#xA;  Radiation Source and are collimated by a specially shaped window in&#xA;  the probe housing. These particles pass across the sensing surface to&#xA;  a Geiger-Muller tube. High voltage is applied to the Geiger-Muller&#xA;  tube to enable it to detect the radiation emitted by the Strontium 90&#xA;  source. Ice accretion on the probe decreases the beta particles&#xA;  detected by the tube. When the particle count drops below a pre-set&#xA;  level, a pulse rate discriminating amplifier energizes an icing signal&#xA;  visible to the flight crew. At this time a heater inside the probe is&#xA;  activated, the ice is removed from the probe, and the probe is ready&#xA;  to begin another icing cycle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Some of these will work in a static situation while others may require the passage from a non icing environment to an icing situation. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2016-01-04T21:29:19.890" LastActivityDate="2016-01-04T21:29:19.890" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24150" PostTypeId="2" ParentId="24146" CreationDate="2016-01-04T22:18:24.580" Score="20" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;I'm sure it's possible to use servo motors to get precise control of the ailerons, elevators or the rudder.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, it isn't. Primary flight control actuators require both rather high forces and quick response time. Electric motors can provide either, but both at the same time is a problem. Hydraulics is still better for that combination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that other actuators that don't require the fast response time (like flaps, gear or horizontal stabilizer foreplane (elevator trim)) are electric in some aircraft.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-01-04T22:18:24.580" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24151" PostTypeId="1" AcceptedAnswerId="24156" CreationDate="2016-01-05T00:17:50.153" Score="1" ViewCount="7784" Body="&lt;p&gt;I saw this question on Google Plus and it seems to be a good question to put here.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a flash pattern for the strobe lights?&#xA;  I think I've read that Airbus has ~2 flashes/sec and Boeing has ~1 flash/sec. I've seen both patterns in the air but I didn't know the aircraft type.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-05T01:26:59.987" Title="Airplane Strobe Light Pattern?" Tags="&lt;aircraft-external-lights&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2016-01-05T08:39:23.463" ContentLicense="CC BY-SA 3.0" />
  <row Id="24152" PostTypeId="2" ParentId="24141" CreationDate="2016-01-05T00:39:14.073" Score="6" Body="&lt;p&gt;At present, it appears to be a design choice rather than any other thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the present generation fighters are transitioning to side-mounted sticks from center sticks. Almost all of the US combat aircraft have side-sticks. In Europe, it's somewhat of a mix- Typhoon (and Gripen) have center sticks, while Rafale has a side stick. The Russians are sticking to a center stick in the T-50.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The location of the control stick depends on a number of factors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Ergonomics- Side stick is better in this regard, limiting the display area in the center; this might be a problem in smaller cockpits.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One of the reasons for using side stick in F-16 was that it (the hand-rest) &lt;a href=&quot;http://www.airspacemag.com/military-aviation/outrageous-adolescence-f-16-180949491/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;supported the Pilot's hand during high 'g' maneuvers&lt;/a&gt;, along with the inclined seat (which is also being used in a number of aircraft).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There is also the personal choice- some pilots may prefer using a center stick, and others, the other way around (there seems to be little problem in transitioning from one to another).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Historically, combat aircraft have had center sticks. Side sticks have come about after fly-by-wire controls. Eurofighter &lt;a href=&quot;http://www.sae.org/aeromag/features/eurofighter/&quot; rel=&quot;noreferrer&quot;&gt;has the following to say in this regard&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Every military aircraft cockpit design has to be something of a compromise, but in a small cockpit, a center stick can cause particular ergonomic difficulties, perhaps limiting the size of the display area for the instruments and/or screens ... That is when options are considered, and one of those would be the sidestick as used in the F-16. However, if the cockpit is sufficiently large and the geometry of the seating position is correct, there is no reason to have anything other than a center stick—and the pilots of the four partner nations agreed. The choice between center sticks and sidesticks is 40% personal—the balance being on technical grounds. We find that F-16 pilots convert easily and naturally to a center stick.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-05T00:39:14.073" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24153" PostTypeId="1" AcceptedAnswerId="24155" CreationDate="2016-01-05T01:09:52.727" Score="25" ViewCount="3898" Body="&lt;p&gt;Recently the FAA released some new regulations that require drone operators, including hobbyist, to register drones with the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I am a novice in both aviation and legalese, can someone please break down the regulations and give me a guideline in layman's terms for whether or not I need to register a drone?&lt;/p&gt;&#xA;" OwnerUserId="2265" LastActivityDate="2017-10-22T01:55:04.437" Title="Do I need to register my drone?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24154" PostTypeId="2" ParentId="24153" CreationDate="2016-01-05T01:15:34.917" Score="7" Body="&lt;p&gt;Well, everything in really basic terms can be found at the &lt;a href=&quot;https://www.faa.gov/uas/registration/&quot; rel=&quot;noreferrer&quot;&gt;FAA Registration Site&lt;/a&gt;. Everything is there on that page.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Owners must register their UAS online if it meets the following guidelines:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Weighs more than 0.55 lbs. (250 g) and less than 55 lbs. (25 kg). Unmanned Aircraft weighing more than 55 lbs. cannot use this registration process and must register using the &lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Registry process&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-05T01:25:57.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24155" PostTypeId="2" ParentId="24153" CreationDate="2016-01-05T01:25:18.610" Score="26" Body="&lt;p&gt;If:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Your unmanned aircraft weighs between 250g and 25kg (including fuel and cargo),&lt;/li&gt;&#xA;&lt;li&gt;You are &lt;em&gt;not&lt;/em&gt; flying under the &lt;a href=&quot;https://www.faa.gov/uas/getting_started/fly_for_fun/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Special Rule for Model Aircraft&lt;/a&gt;, also known as section 336&lt;/li&gt;&#xA;&lt;li&gt;You intend to operate it outdoors, and&lt;/li&gt;&#xA;&lt;li&gt;You are operating it in the United States,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;you need to register your drone through &lt;a href=&quot;https://registermyuas.faa.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA's online registration system&lt;/a&gt;.  If your drone is heavier than 25kg, you need to go through the &lt;a href=&quot;https://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/UA/&quot; rel=&quot;nofollow noreferrer&quot;&gt;regular aircraft registration process&lt;/a&gt;.  If your drone is ligher than 250g, or you are only operating it indoors, you do not need to register it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, if you are operating the drone for commercial purposes, you must have a &lt;a href=&quot;https://www.faa.gov/uas/getting_started/fly_for_work_business/becoming_a_pilot/&quot; rel=&quot;nofollow noreferrer&quot;&gt;remote pilot airman certificate&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note: if you are younger than 13 years old, someone who is 13 or older needs to register your drone for you.)&lt;/p&gt;&#xA;" OwnerUserId="1677" LastEditorUserId="62" LastEditDate="2017-08-02T13:11:44.270" LastActivityDate="2017-08-02T13:11:44.270" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24156" PostTypeId="2" ParentId="24151" CreationDate="2016-01-05T01:26:59.987" Score="6" Body="&lt;p&gt;It appears that the flash sequences in &lt;a href=&quot;https://aviation.stackexchange.com/a/2758/9731&quot;&gt;Airbus and Boeings are different&lt;/a&gt;. For example, the following image gives the flashing sequence in Airbus A320:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2Tzfc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Tzfc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=14&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwj19MLHt5HKAhWGNhoKHaUzBhAQFghjMA0&amp;amp;url=http%3A%2F%2Futcaerospacesystems.com%2Fcap%2Fsystems%2FInteriors%2520Documents%2FLighting%2520Systems%2F06%2520Anti-Collision%2520Lights%2F06_0010%2520LED%2520Anti-Collision%2520Lighting%2520System%2520A320.pdf&amp;amp;usg=AFQjCNFez9CHYQ8a2fL4qXnhlnWbg5M7BA&amp;amp;bvm=bv.110151844,d.d2s&quot; rel=&quot;nofollow noreferrer&quot;&gt;LED Anticollision Lighting system for A320&lt;/a&gt; by UTC Aerospace Systems&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the differing flashing sequences of different lights. Also, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/9722/do-lights-on-aircraft-flash-in-a-specific-pattern&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as regulations are concerned, &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/23.1401&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 23.1401 - Anticollision light system&lt;/a&gt; states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Flashing characteristics. The arrangement of the system, that is, the number of light sources, beam width, speed of rotation, and other characteristics, must give an effective flash frequency of not less than 40, nor more than 100, cycles per minute. The effective flash frequency is the frequency at which the airplane's complete anticollision light system is observed from a distance, and applies to each sector of light including any overlaps that exist when the system consists of more than one light source. In overlaps, flash frequencies may exceed 100, but not 180, cycles per minute.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-05T01:26:59.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24157" PostTypeId="1" AcceptedAnswerId="24159" CreationDate="2016-01-05T02:03:45.197" Score="24" ViewCount="3910" Body="&lt;p&gt;I am sure when getting their type rating for Airbus FBW aircraft, pilots learn how to fly in alternate and direct law. After that, how much opportunity do they get to practice this skill?&lt;/p&gt;&#xA;&lt;p&gt;On Air France 447 and Indonesia AirAsia flight 8501, the A/P switched off unexpectedly and the control law degraded to alternate 2. It appears in both situations that the PF had trouble stabilizing the aircraft roll attitude. It's difficult to determine whether this contributed to the pitch up and eventual stall but the original pitch up command may have been inadvertent while struggling to level the wings.&lt;/p&gt;&#xA;&lt;p&gt;Under normal law, which pilots are accustomed to flying, the FAC calculates the amount of aileron deflection required to turn the amount of lateral sidestick deflection into a rate of roll with a maximum of 15° per second. In alternate 2 law the computer cannot make these calculations so it becomes direct stick-to-aileron control.&lt;/p&gt;&#xA;&lt;p&gt;This can mean that the aircraft responds very differently than what the pilot is used to. Sometimes the difference may be slight but at high speed and high altitude the same stick deflections can result in a significantly higher roll rate.&lt;/p&gt;&#xA;&lt;p&gt;Additionally the stick does not provide tactile feedback as to how much force is required to move the control surfaces. With conventional flight controls &amp;quot;roll or pitch rate would more directly correlate with the force applied on the control wheel, and not the amount of deflection required.&amp;quot;&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;These things combined can result in the pilot over-controlling. The control inputs can get out of phase with aircraft movements resulting in pilot induced oscillation in the roll axis. This occurred in both of the above accidents.&lt;/p&gt;&#xA;&lt;p&gt;It must be terribly disconcerting for a pilot when the A/P disconnects and they are handed control of an aircraft they fly every day, but doesn't respond the way they are used to. I'm wondering how much practice they get at flying in this configuration, either in a simulator or in the aircraft itself. Do most airlines flying FBW aircraft require this regularly? Does Airbus - or anyone else - recommend any amount of further training or practice? Have these recommendations changed in light of the accidents?&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;em&gt;Bill Palmer, Understanding Air France 447&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="4095" LastEditDate="2020-12-11T11:13:19.223" LastActivityDate="2020-12-11T11:13:19.223" Title="Do Airbus pilots have to practice flying in alternate law?" Tags="&lt;flight-controls&gt;&lt;airbus&gt;&lt;fly-by-wire&gt;&lt;af447-accident&gt;" AnswerCount="3" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="24158" PostTypeId="2" ParentId="3513" CreationDate="2016-01-05T09:06:38.393" Score="5" Body="&lt;p&gt;Another thing to remember about the specific fuel consumption of a turbine engine is that it is HIGHLY dependent on the size of the engine. Small gas turbines (of the sort that may be used in small private aircraft) are inherently inefficient because they cannot run the kinds of pressure ratios required for high efficiency. For instance, a 2180HP PW119B has a pressure ratio of 13.2:1 and a SFC of .49. Step that up to an 11000HP Europrop TP400-D6, and pressure ratio climbs to 25:1. SFC drops to .39. And the 56300HP GE LM6000 (a marine and power generation turboshaft based on the CF6 turbofan) has a pressure ratio of around 32:1 and a SFC of .32. Because of this, piston engines have a fuel efficiency advantage at low power outputs, but a fuel efficiency DISadvantage at high power outputs. Piston engines therefore are favored in small aircraft for this reason and initial cost. But turbines make MUCH more sense in larger aircraft due to both their higher efficiency than large piston engines and reduced maintenance costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone mentioned helicopters here. And helicopters are a different animal altogether. A basic characteristic of helicopters is the fact that they require LOTS of power on a continuous basis. This would take a HUGE toll on piston engines in terms of reliability (think of how long a car engine would last if you constantly drove it at full throttle), but is not an issue for a turbine. Turbines are also smaller and lighter (ever seen a Sikorsky Mojave with its ridiculously huge piston engines)? All of these factors make turbines MUCH more practical than piston engines in helicopters.&lt;/p&gt;&#xA;" OwnerUserId="12899" LastActivityDate="2016-01-05T09:06:38.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24159" PostTypeId="2" ParentId="24157" CreationDate="2016-01-05T10:25:17.860" Score="12" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;It appears in both situations that the PF had trouble stabilizing the aircraft roll attitude.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;https://www.flightglobal.com/news/articles/stall-training-still-constrained-by-limits-of-knowledge-383565/&quot; rel=&quot;noreferrer&quot;&gt;roll control is secondary&lt;/a&gt; when recovering from a stall. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Restoring normal pitch and roll, he stresses, are &quot;of secondary importance&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The situation required that the pilots heed the stall warnings, be aware of the stall and put the nose down to trade altitude for airspeed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Have these recommendations changed in light of the accidents?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can read the recommendations in the official accident reports. These usually explicitly state what such changes should be. I believe it is very rare (except when investigators disagree) for regulators, manufacturers and airlines to ignore any such recommendations.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.bea.aero/en/enquetes/flight.af.447/rapport.final.en.php&quot; rel=&quot;noreferrer&quot;&gt;AF447&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://kemhubri.dephub.go.id/knkt/ntsc_aviation/baru/Final%20Report%20PK-AXC.pdf&quot; rel=&quot;noreferrer&quot;&gt;QZ8501&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From what I recall, the major problems in these two incidents were not that the pilots were simply unfamiliar with how control inputs affect flight in alternate law. major problems were that the pilots did not seem to be aware that they were in alternate law or even aware that the aircraft was stalled. In both cases the pilots were confused, failed to follow procedures and failed to coordinate their actions effectively (i.e. CRM failures)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus &lt;a href=&quot;http://www.dream-air.ru/new/pilotam/FCTM_ENV_LR-1-.pdf&quot; rel=&quot;noreferrer&quot;&gt;Flight Crew Training Manuals&lt;/a&gt; do cover alternate law.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Recommendations included&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5.3 Aircraft Manufacturer&lt;br&gt;&#xA;  1. The KNKT recommends that Airbus to consider in developing a means for&#xA;  flight crews to effectively manage multiple and repetitive Master Caution&#xA;  alarms to reduce distraction.&lt;br&gt;&#xA;  2. The KNKT recommends that Airbus to consider and review the FCTM&#xA;  concerning the Standard Call-Outs in all phases of flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Indonesian report lists  in some detail the actions taken by the airline and includes an Airbus article &quot;What is a stall? How a pilot should react in front of a stall situation&quot;. It also includes some guidance issued by Airbus which includes recommendations concerning upset training in various control laws&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9lH5t.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9lH5t.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;After that how much opportunity do they get to practice this skill?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends on airline (and relevant regulators) more than on manufacturer. Upset recovery is probably something that all pilots should be trained in, and maintain familiarity with, regardless of who manufactured the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-01-05T11:09:22.400" LastActivityDate="2016-01-05T11:09:22.400" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24160" PostTypeId="1" CreationDate="2016-01-05T11:50:22.480" Score="14" ViewCount="36239" Body="&lt;p&gt;I was talking to a pilot, and he said that the alpha floor had been activated, and I did not have time to ask him to explain this. So, can you clarify my doubt, please?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2018-05-22T02:18:51.437" Title="What does &quot;alpha floor&quot; mean?" Tags="&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24162" PostTypeId="2" ParentId="24160" CreationDate="2016-01-05T12:07:03.963" Score="8" Body="&lt;p&gt;Alpha floor is a thrust function which provides TOGA thrust regardless of thrust lever position in Airbus. From &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=10&amp;amp;ved=0ahUKEwiq2a3QzpLKAhWGuRoKHcesB4EQFghXMAk&amp;amp;url=http%3A%2F%2Fwww.airbus.com%2Fsupport%2Fpublications%2F%3FeID%3Dmaglisting_push%26tx_maglisting_pi1%255BdocID%255D%3D41128&amp;amp;usg=AFQjCNH2zsVyKqTa-8CM5FDVo3vX83T7hw&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Airbus Technical Digest FAST 20&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Alpha Floor is a low speed protection (in normal law) which is purely an&#xA;  autothrust mode. When activated, it provides TOGA thrust. As the aircraft&#xA;  decelerates into the alpha protection range, the Alpha Floor is activated,&#xA;  even if the autothrust is disengaged. Activation is roughly proportional to&#xA;  the rate of deceleration. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... at low speeds, if a rapid avoidance manoeuvre is required to avoid terrain, windshear or another aircraft, it is safe to rapidly pull the sidestick fully aft and/or bank and hold it there. The aircraft will pitch up&#xA;  to max Alpha, engage TOGA thrust and climb away. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that this protection is only available under normal law and &lt;a href=&quot;http://www.airbusdriver.net/airbus_fltlaws.htm&quot; rel=&quot;noreferrer&quot;&gt;is lost under alternate law&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-05T12:07:03.963" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24163" PostTypeId="1" AcceptedAnswerId="24169" CreationDate="2016-01-05T13:05:55.613" Score="13" ViewCount="5363" Body="&lt;p&gt;According to the procedures, when going around, due to windshear, pilots shouldn't change the aircraft's configuration, such as flaps position and landing gear extension. If changing, would the aircraft lose the lift? why?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-01-05T19:29:11.527" Title="Why shouldn't the pilot change the aircraft's configuration while avoiding windshear during landing?" Tags="&lt;windshear&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24164" PostTypeId="2" ParentId="24163" CreationDate="2016-01-05T13:32:48.170" Score="-1" Body="&lt;p&gt;Well, the configuration at landing is for low speeds, if the flaps are pulled up, the airplane might stall because of low speed air separation and might take the necessary lift away to get get away from the windshear. And as a comment above says, the flaps also help with stability when manoeuvring the airplane at low speeds. Gears are left down in case of unwanted touchdown (This is windshear, so it might happen).&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-05T13:32:48.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24165" PostTypeId="2" ParentId="24163" CreationDate="2016-01-05T14:26:54.603" Score="14" Body="&lt;p&gt;As far as landing is concerned, it is better to leave the landing gear down because if something goes down and the aircraft touches the ground, it is better to do so with the landing gear rather than the aircraft fuselage. Also, the retraction process may increase drag, not what is desired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During landing, the retraction of flaps (which may be already at their max) can cause loss of lift (as you noted). Reduced airspeed due to windshear causes loss of lift; retracting the flaps in this condition is not desirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also the point that during the critical moments when the pilots are trying to pilot the aircraft during wind shear, their attention should be in flying the aircraft and not in fiddling with controls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From FAA Advisory Circular 00-54 Pilot Windshear Guide:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CONFIGURATION&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Maintain flap and gear position until terrain clearance is assured. Although a small performance increase is available after landing gear retraction, initial performance degradation may occur when landing gear doors open for retraction. While extending flaps during a recovery after liftoff may result&#xA;  in a performance benefit, it is not a recommended technique because:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1) Accidentally retracting flaps (the usual  direction of movement) has a large adverse impact on performance.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2) If landing gear retraction had been initiated prior to recognition of the encounter, extending flaps beyond a takeoff flap setting might result in a continuous warning horn which distracts the crew.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-05T14:26:54.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24166" PostTypeId="1" AcceptedAnswerId="25870" CreationDate="2016-01-05T15:51:44.697" Score="3" ViewCount="222" Body="&lt;p&gt;Recovery from unusual attitudes is required during primary training and must be demonstrated during the checkride. In the case of an incapacitated or disoriented pilot, will activating a single-axis autopilot in ROL mode while in an unusual attitude safely recover straight-and-level flight?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2016-03-05T21:04:28.740" Title="Is any single-axis autopilot for a light piston single certified for unusual-attitude recovery?" Tags="&lt;general-aviation&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24169" PostTypeId="2" ParentId="24163" CreationDate="2016-01-05T16:20:18.683" Score="6" Body="&lt;p&gt;During extension and retraction the gear drag is substantially higher than in the extended position. This has two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When the gear moves, the first thing to happen is that the big bay doors open. They are also the last to close after the gear has reached its new position. During that time, the large cavity of the gear bay will cause additional drag, sometimes as much as half of the drag of the extended gear.&lt;/li&gt;&#xA;&lt;li&gt;When the wheels are close to the fuselage, their drag contribution is higher than when they are at some distance due to higher interference drag.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6cX3U.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6cX3U.png&quot; alt=&quot;Hoerner Fluid Dynamic Drag, Chapter 13 page 14&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure 38 from S. Hoerner's &lt;a href=&quot;https://openlibrary.org/books/OL17462293M/Fluid-dynamic_drag&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fluid Dynamic Drag&lt;/a&gt;, Chapter 13 page 14.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that after landing gear extension &lt;a href=&quot;https://www.youtube.com/watch?v=w4bTPq6qNTs&quot; rel=&quot;nofollow noreferrer&quot;&gt;the biggest doors close again&lt;/a&gt;. The time it takes to retract the gear is similar to that where windshear will cause the biggest airspeed loss. Consequently, cycling the gear will increase drag over that of the extended configuration, and any improvement in aerodynamic quality due to a retracted gear can only be gained after the worst is over and the aircraft will speed up and climb anyway, regardless of gear position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, changing the configuration will be distracting in a stressful situation, and the risk of a wrong configuration change is increased. It is better to let the pilot focus on flying the plane than to burden her/him with additional work.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-05T19:29:11.527" LastActivityDate="2016-01-05T19:29:11.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24171" PostTypeId="2" ParentId="24163" CreationDate="2016-01-05T17:44:37.667" Score="2" Body="&lt;p&gt;As usual, &lt;a href=&quot;https://aviation.stackexchange.com/a/24169/755&quot;&gt;Peter's answer&lt;/a&gt; is correct. However, I wanted to address the last part of the question regarding if lift would be lost, since I didn't see a direct answer to it in the other answers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, the aircraft will lose lift if you retract the flaps. The whole purpose of flaps is to increase lift at low airspeeds in order to allow the aircraft to takeoff and land with lower airspeeds than it would be able to use if it had no flaps. However, flaps also increase drag, which is why you retract them once the airspeed is high enough to not need them. During a landing, flaps will normally be set at or near their maximum extension, which allows the aircraft to fly quite a bit slower than it would otherwise be able to fly. If you suddenly retract the flaps while flying at final approach speed, you will lose a lot of lift and potentially even stall the aircraft. Needless to say, that's not good on final approach, especially if you're trying to go around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that flaps increase both lift and drag at any (positive) airspeed, so retracting them will always result in less lift, but also less drag.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-05T17:44:37.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24173" PostTypeId="2" ParentId="24166" CreationDate="2016-01-05T20:20:30.587" Score="2" Body="&lt;p&gt;Generally, no.  There's always an exception out there someplace, but I've never seen an autopilot that is advertised as being able to recover from an unusual attitude situation.  Depending on exactly what the attitude is, the mode of the autopilot, and its specific capabilities &amp;amp; mechanical limitations, you MIGHT be able to get out of an unusual attitude that way, but I wouldn't count on it.  And it's certainly never taught that way anywhere that I've been... you're taught to recognize-confirm-recover by flying out of the unusual attitude yourself, rather than relying on the automation to do it for you.  (In fact, if you get into an unusual attitude, chances are decent that either mismanagement of or a failure in the automation contributed to getting you there!)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given the wide range of possibly unusual attitudes &amp;amp; aggravating circumstances (i.e. engine out, rudder out-of-trim, shifting or shearing winds, structural damage, failed pitot/static instruments, failed gyro, etc etc), I'd be very surprised if any manufacturer would ever claim that their autopilot could be relied upon for this task.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="2171" LastEditDate="2016-01-05T20:25:23.783" LastActivityDate="2016-01-05T20:25:23.783" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24174" PostTypeId="2" ParentId="24146" CreationDate="2016-01-05T20:33:42.893" Score="7" Body="&lt;p&gt;As mentioned already, hydraulic systems are fast and powerful but you need to also consider how extremely efficient and simple they are. Reducing complexity reduces maintenance costs which is a large factor. Flaps, trim devices, and landing gear doors are the only good places to use motors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the specific example you're looking for was the Sioux City DC 10 accident in the 80's (&lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/United_Airlines_Flight_232&lt;/a&gt;). The DC10 had an achilles heel in that all of the hydraulic lines ran parallel to each other in one section of the tail. When the tail engine suffered a catastrophic failure a fan blade struck through all 3 (?) hydraulic lines which led to a complete hydraulic system loss. Airplanes since then have been designed with the hydraulic lines running in separate places and further apart (i.e. different sides of the rudder) to prevent total flight control system failure.&lt;/p&gt;&#xA;" OwnerUserId="9298" LastActivityDate="2016-01-05T20:33:42.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24177" PostTypeId="2" ParentId="24153" CreationDate="2016-01-06T01:00:06.053" Score="2" Body="&lt;p&gt;I would highly recommend following the AMA's guidance on this matter.  They've been doing this for many years now with safety as their primary mission before the FAA decided to stick their heavy hand into the matter after the increasing popularity of quad-rotor models led to several regrettable high-profile incidents by new flyers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As of today (1/5/2016) the AMA is currently in negotiations with the FAA to achieve at the very least an exemption for AMA members, and their current advice on the matter is&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Don't register yet as the deadline has not passed and you are not breaking the law until it does.&lt;/li&gt;&#xA;&lt;li&gt;Submit comments to the FAA expressing your opinion of the new legislation.&lt;/li&gt;&#xA;&lt;li&gt;Additional information will no doubt be posted on &lt;a href=&quot;http://amablog.modelaircraft.org/amagov/&quot; rel=&quot;nofollow&quot;&gt;their blog&lt;/a&gt; as the situation evolves.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1043" LastActivityDate="2016-01-06T01:00:06.053" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24179" PostTypeId="1" AcceptedAnswerId="24182" CreationDate="2016-01-06T05:29:40.157" Score="4" ViewCount="739" Body="&lt;p&gt;I had a question about restricted airspace that I wanted to clear up before resuming my training Sunday; you know, to maximize time in the air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airport I am training at is &lt;a href=&quot;http://www.airnav.com/airport/KMRH&quot; rel=&quot;nofollow&quot;&gt;KMRH&lt;/a&gt; and it's surrounded by lots of restricted/military airspace/MOAs. From what I have read, restricted airspace requires permission to fly in; however we have never done that, we just call up on Unicom and state our intentions to other pilots. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone here could &lt;a href=&quot;https://skyvector.com/?ll=34.70720766540928,-76.65941007477404&amp;amp;chart=301&amp;amp;zoom=3&quot; rel=&quot;nofollow&quot;&gt;look at an online sectional of the area&lt;/a&gt; and get an idea of what I am saying and attempt to explain this to me it would be very helpful. If nobody can crack through my thick skull, I can always ask my CFI!&lt;/p&gt;&#xA;" OwnerUserId="12677" LastEditorUserId="19" LastEditDate="2017-03-17T08:56:32.703" LastActivityDate="2017-03-17T08:56:32.703" Title="Is special permission required to take off from a field within restricted airspace?" Tags="&lt;military&gt;&lt;flight-training&gt;&lt;airspace&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24180" PostTypeId="1" CreationDate="2016-01-06T05:36:47.343" Score="10" ViewCount="2129" Body="&lt;p&gt;&lt;strong&gt;Maximum theoretical lift of a plane as a function of engine power and surface of the wings?&lt;/strong&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that the maximum static thrust of a propeller turned by an engine of power $P$ can not be greater than: &#xA;$$Thrust_{max}=\sqrt[3]{2\pi(\frac{D}{2})^2 \rho P^2}$$&#xA;where $\rho$ is the density of the air and $D$ the diameter of the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for a formula that gives the maximum theoretical lift of a plane which flies horizontally. After half a page of demonstrations I have found a relation:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$Lift_{max}=\sqrt[3]{2S \rho P^2}$$&#xA;but I am not sure if it is correct ($S$ is the total surface of the wings).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 1&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two examples that show the formula for max lift gives lifts smaller than the loaded weight of the plane. I do not know why.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;Cessna 172&lt;/a&gt;: Gross weight - $1,111kg$, Powerplant - $160 hp$, Wing area - $16.2 m^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$Lift_{max}=(2 * 16.2 m^2 * 1.2 kg/m^3 * (160 hp)^2)^{1/3}=837 kgf&amp;lt;1,111kgf$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Canada_DHC-6_Twin_Otter&quot; rel=&quot;nofollow&quot;&gt;de Havilland DHC-6 100 Twin Otter&lt;/a&gt;: Gross weight - $5,246kg$, Powerplant - $2*579 eshp$, Wing area - $39 m^2$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$Lift_{max}=(2 * 39 m^2 * 1.2 kg/m^3 * (2 * 579 hp)^2)^{1/3} = 4,198 kgf&amp;lt;5,246kgf$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 2&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have tried a different demonstration that stars from the known relations:&#xA;$$Lift={0.5 \rho S C_L V^2}$$&#xA;$$Drag={0.5 \rho S C_D V^2}$$&#xA;$$Power=Drag * V$$&#xA;By eliminating the speed of the plane, $V$, the lift result as being:&#xA;$$Lift = \sqrt[3]{2S \rho P^2 \frac{C_L^3}{4 C_D^2}}$$&#xA;It appears that this new lift can be greater than $\sqrt[3]{2S \rho P^2}$ as long as $\frac{C_L^3}{4 C_D^2}$ does not seem to be restricted to always remain less than 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 3&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the formulas for $C_D$ an $L_{max}$, suggested to me by Peter Kampf and mnunos, I have made some evaluations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$C_D = C_{D0} + \frac{C_L^2}{\pi\cdot AR\cdot\epsilon}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$L_{max}=\frac{1}{2}\cdot \sqrt{3\pi AR\epsilon}\cdot \sqrt[3]{\frac{P^2\eta^2\rho S}{4 \sqrt{C_{D0}}}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the assumed values: $\eta=0.7$, $\epsilon=0.8$, $C_{D0}=0.03$, $\rho=1.2\: kg/m^3$ and the data taken from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;Cessna 172&lt;/a&gt; general characteristics: $P = 160\:hp$, $S=16.2\:m^2$ and $AR=7.32$, I get:&#xA;$$L_{max,\:\eta=0.7}=2199\:kgf$$&#xA;However, only $57.451\:hp$ are necessary for lifting $1111\:kg$ (horizontal flight), the rest up to $160\:hp$ can be used for climbing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the relation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$m_{plane}gV_{climb} = \eta(160\:hp - 57.451\:hp)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I get $V_{climb}= 4.913\:m/s$ which is significantly greater than the rate of climb 3.66 m/s the Cessna 172 has.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems that working with $C_{D0}$ and $\epsilon$ gives only a quite rough estimate of the max lift. Without knowing the actual $C_L=C_L(C_D)$ little can be said about the real maximum possible lift of a certain plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 4&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum theoretical thrust of an ideal helicopter propeller having the diameter identical to the wingspan, $11\:m$,  of a Cessna 172:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$T_{max,Diameter\:prop=11\:m}=(2 * pi * (11 m / 2)^2 * 1.2 kg/m^3 * (160 hp)^2)^{1/3} = 1 509.95\:kgf$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;is considerably smaller than the max lift of the plane,  $L_{max,\:\eta=0.7}=2199\:kgf$, I calculated in &lt;em&gt;Update 3&lt;/em&gt;. Is such a result logical?  Does it have an explanation?&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="19" LastEditDate="2016-10-17T07:57:56.720" LastActivityDate="2019-04-14T19:33:33.903" Title="What is the maximum theoretical lift of a plane as a function of engine power and surface of the wings?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24181" PostTypeId="1" AcceptedAnswerId="24186" CreationDate="2016-01-06T05:49:29.437" Score="51" ViewCount="16483" Body="&lt;p&gt;A useful little quirk about the 747 is that it can &lt;a href=&quot;http://australianaviation.com.au/2011/07/qantas-744-ferries-spare-engine-to-johannesburg/&quot; rel=&quot;noreferrer&quot;&gt;ferry a fifth engine on the wing&lt;/a&gt;, for when another aircraft is stranded somewhere in the world. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SaE8r.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SaE8r.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Does the A380 have the same capability? If not, how would an airline manage an aircraft needing a new engine whilst away from a maintenance base?&lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="7532" LastEditDate="2016-01-06T11:17:23.307" LastActivityDate="2017-09-06T07:52:29.597" Title="Can the A380 ferry an extra engine, like the 747?" Tags="&lt;engine-failure&gt;&lt;boeing-747&gt;&lt;airbus-a380&gt;&lt;ferry-flight&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24182" PostTypeId="2" ParentId="24179" CreationDate="2016-01-06T06:12:37.680" Score="3" Body="&lt;p&gt;&quot;Restricted Airspace&quot; is exactly that; it comes with various restrictions that vary between areas. According to the AIM,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Restricted areas denote the existence of unusual, often invisible, hazards to aircraft such as artillery firing, aerial gunnery, or guided missiles. Penetration of restricted areas without authorization from the using or controlling agency may be extremely hazardous to the aircraft and its occupants.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My old CFI's example was flying through an active artillery range. The guns are required to stop while aircraft are near. They will find you and have some very strongly-worded advice for you when you land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like MOAs, these areas can be &quot;hot&quot; at certain times. The difference here would mean that you shouldn't fly into restricted airspace while it is &quot;hot&quot; while there is no such restriction with MOAs, though you are requested to route around them if possible.  Some areas might require additional visibility and/or altitude requirements or restrict based on the type and class of aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Prohibited Airspace&quot; is not allowed to be entered at any time without prior authorization of the controlling agency or explicit permission during an emergency.&lt;/p&gt;&#xA;" OwnerUserId="12904" LastActivityDate="2016-01-06T06:12:37.680" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24183" PostTypeId="2" ParentId="3513" CreationDate="2016-01-06T09:34:55.053" Score="1" Body="&lt;p&gt;About the questions of knock limiting the size of piston engines and 107000HP marine diesels, knock is not an issue. Rather, the limitation on the size of piston engines is PHYSICAL SIZE. Reliability is also an issue as the number of reciprocating moving parts skyrockets. But size is what REALLY kills the deal when it comes to piston engines. ln my other post, I mentioned the Sikorsky Mojave. That helicopter looks downright bizarre because of the large pods protruding from each side of the fuselage. Those pods each contain a 2100HP Pratt and Whitney R-2800. By comparison, the 5000HP Honeywell T-55s on a Chinook look almost like toys. If you wanted to power a Boeing 747 with piston engines, each engine would probably have to be the size of a decent sized plane in order to produce the ~55000-60000HP that each CF-6 produces (consider how big the R-4360, the largest production aircraft piston engine was, and it topped out at around 4000HP). The 107000HP marine engine is an extreme example of this. These engines are literally called 'cathedral engines', and live up to that name with 38 inch bores. Yes, it may produce about as much power as two CF-6s. But these engines are as large as they sound, and not exactly aircraft material. On the other hand, size is not so much an issue in an ocean going ship. And reliability is not too bad for these engines since the large size means that a smaller number of super large components can be used.&lt;/p&gt;&#xA;" OwnerUserId="12899" LastEditorUserId="12899" LastEditDate="2016-01-06T09:42:16.947" LastActivityDate="2016-01-06T09:42:16.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24185" PostTypeId="2" ParentId="24181" CreationDate="2016-01-06T11:36:55.817" Score="21" Body="&lt;p&gt;The A380 does not appear to have the capability to transport an extra engine under the wing. Higher engine reliability combined with widespread availability of air cargo transport makes this option redundant in modern jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case engines are needed for an A380, they &lt;a href=&quot;http://www.rolls-royce.com/products-and-services/civil-aerospace/products/civil-large-engines/videos/trent-900-on-board.aspx&quot;&gt;can be transported in a 747-400 Freighter&lt;/a&gt;* or the aircraft &lt;a href=&quot;http://www.avweb.com/avwebflash/news/A380-Flies-5000-Miles-On-Three-Engines-220951-1.html&quot;&gt;can be flown with three engines&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Trent 900 can be transported in a 747-400F without disassembling. For Engine Alliance GP7000, you'll &lt;a href=&quot;http://cargofacts.com/up-close-with-the-an-124/&quot;&gt;need an An-124&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-06T11:36:55.817" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24186" PostTypeId="2" ParentId="24181" CreationDate="2016-01-06T14:35:43.150" Score="47" Body="&lt;p&gt;One of the main reasons the 747 was given the ability to ferry an engine was due to the lack of large cargo aircraft available at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't forget the 747 was a major game changer when it came out, it was designed to replace the 707/DC-8, and was almost twice the size of these aircraft. As a result, there just wasn't anything available to transport a 747 engine by air if needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was a major problem that had the potential to affect sales of the aircraft, and so they had to find a solution to this. It wasn't until the 747 began to be introduced as a cargo carrier that it was possible to transport these engines by air, in the hold of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the introduction of the A380, there was no need to add engine ferry capabilities, as large cargo aircraft were common enough to transport them.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastEditorUserId="7611" LastEditDate="2016-01-07T16:26:02.857" LastActivityDate="2016-01-07T16:26:02.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24187" PostTypeId="2" ParentId="24179" CreationDate="2016-01-06T14:46:39.543" Score="15" Body="&lt;p&gt;The most obvious point to make here is that KMRH is not in restricted airspace: the sectional shows that it's in uncontrolled class G airspace, with class E at 700' AGL. But having said that, there is indeed a lot of &lt;a href=&quot;https://aviation.stackexchange.com/q/20877/62&quot;&gt;special use airspace&lt;/a&gt; nearby:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;W-122 is a warning area&lt;/li&gt;&#xA;&lt;li&gt;R5306A and R-5306D are restricted areas&lt;/li&gt;&#xA;&lt;li&gt;A-530 is an alert area&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can't enter the restricted areas without permission from the controlling authority, but you can enter the warning and alert areas if you want. More details of each area are &lt;a href=&quot;https://skyvector.com/?ll=31.75661138994275,-79.46021327138743&amp;amp;chart=30&amp;amp;zoom=4&quot; rel=&quot;nofollow noreferrer&quot;&gt;on the sectional chart&lt;/a&gt;, the FAA's &lt;a href=&quot;https://sua.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;SUA site&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/7400_8X_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7400.8X&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the sectional, it looks to me like A-530 is a 'gap' in the restricted areas to give access to KMRH and the three private airfields nearby. R-5306 A and D are from the ground to 18,000 MSL (up to but not including FL180, to be precise) and operate continuously. If the A-530 airspace were the same then there would be no way in or out of KMRH (over land, at least) without getting permission every time. Because A-530 is sandwiched between two restricted areas, I guess there's probably a lot of military traffic around and that's why it's an alert area rather than normal class E airspace.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-01-06T14:46:39.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24189" PostTypeId="2" ParentId="700" CreationDate="2016-01-06T20:46:08.700" Score="1" Body="&lt;p&gt;Turbine engines of the same family, all rotate in the same direction. Imagine having to build a turbine engine that rotated opposite. The cost would be over the top. The airlines would be inventorying duplicate spares for the engines. &lt;/p&gt;&#xA;" OwnerUserId="12916" LastActivityDate="2016-01-06T20:46:08.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24190" PostTypeId="1" AcceptedAnswerId="24195" CreationDate="2016-01-06T23:33:59.920" Score="10" ViewCount="12379" Body="&lt;p&gt;I got Aircraft Design: A conceptual approach for Christmas, and I'm having a hard time with lift coefficients because I honestly have no idea what &quot;lift force per unit span&quot; means, so can someone please explain this to me?&lt;/p&gt;&#xA;" OwnerUserId="580" LastActivityDate="2016-01-07T12:54:56.333" Title="What is the lift force per unit span?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24191" PostTypeId="2" ParentId="24190" CreationDate="2016-01-07T00:01:05.783" Score="4" Body="&lt;p&gt;Imagine that the wing is a carrot, and chop it up as you would chop a carrot into discs. The lift (force) produced by a slice of thickness 1 is the lift (force) per unit span of that slice. (&quot;Thickness 1&quot; could be in whatever units you choose, so another way to look at that is to divide the lift by the thickness of the slice.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a uniform (straight, not tapered, swept, or twisted) wing, every slice produces the same amount of lift, so as Riccati points out, the lift per unit span is just the total lift divided by the wing span. However, on a wing whose shape varies from the fuselage to the tip, each slice is slightly different. A tapered wing might look a bit like a very conical carrot, and the lift per unit span decreases smoothly from the root to the tip, just like the diameter of each disc decreases as you get towards the tip of the carrot. (I'm not saying the shape of the carrot is related at all: it's just a way of thinking about considering each slice separately.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you can use total lift to compare different wings, you can use lift per unit span to compare wings in a way that's independent of their span. A wing twice as long will produce twice the lift (ignoring real-world effects like flex and prop wash), but it will have the same lift per unit span, because it has the same thickness and shape as the shorter wing. More usefully, you can use it to look at different parts of the same wing: to compare the root and the tip. Later in your book, you'll see charts showing how the lift per unit span varies along the length for different shapes/designs of wing.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-01-07T00:01:05.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24192" PostTypeId="2" ParentId="24190" CreationDate="2016-01-07T00:47:54.650" Score="4" Body="&lt;p&gt;Consider a finite (three dimensional) wing producing lift. It would be difficult for us to calculate the total lift and exact lift distribution of the wing unless it is quite simple. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to deal with it is to 'slice' the wing into a number of segments for which the lift force can be found and the take into account the effects of variation of various wing parameters like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Chord&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Geometric twist&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aerodynamic twist (airfoil shape).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The lift per unit span of the wing can be found from the lift coefficient of the airfoil- basically, we are assuming that the flow over a finite wing can be treated as locally two-dimensional and finding the forces on the wing using this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, take a three dimensional wing and then slice it into small pieces so that the lift is essentially constant within each (i.e. the airfoil section and angle of attack is constant). For each of the slices, it is possible to find the lift (from airfoil and flow characteristics). This gives the lift per unit span (unit span here means the size satisfying above conditions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the total lift can be found by simply adding the lifts from various sections. Another thing is that the spanwise variation of the lift per unit span gives the lift distribution of the wing- helping us to compare various wing planforms- like elliptical vs rectangular etc.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-07T00:47:54.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24193" PostTypeId="1" AcceptedAnswerId="24194" CreationDate="2016-01-07T07:32:15.653" Score="25" ViewCount="5102" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/700/do-turbine-engines-on-multi-engine-aircraft-rotate-in-opposite-directions-to-off&quot;&gt;here&lt;/a&gt; it is seen that many multi-engine propeller planes spin their propellers in opposite directions. To avoid producing &quot;left&quot; and &quot;right&quot; types of the engine, a gearbox is fitted. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast, jet engines usually spin in the same direction. Why is the spinning direction less important for a jet engine than for a propeller engine? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Boeing 777 may have a turbine fan as large as 325 cm in diameter (GE90-115B). Not every propeller is that large.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2020-12-15T15:37:04.400" Title="Why is rotating engines in opposite directions more important for a propeller-driven plane than a jet?" Tags="&lt;multi-engine&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24194" PostTypeId="2" ParentId="24193" CreationDate="2016-01-07T08:19:49.700" Score="32" Body="&lt;p&gt;This is sort of explained in the &lt;a href=&quot;https://aviation.stackexchange.com/questions/700/do-turbine-engines-on-multi-engine-aircraft-rotate-in-opposite-directions-to-off&quot;&gt;linked question&lt;/a&gt; already. Specifically &lt;a href=&quot;https://aviation.stackexchange.com/a/7425/524&quot;&gt;this answer&lt;/a&gt; (which I consider better than the accepted one above it) says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Today, high power propeller aircraft tend to use identical engines but left- and right-handed gearboxes so the propellers run in both directions. This is less due to gyro effects and mostly to produce benign stall characteristics. The prop wash of a propeller increases the local angle of attack on the wing on one side and decreases it on the other side, so the wing will stall first on the side with bigger angle of attack. If this side is always to the right of the propellers, the aircraft will roll right in a stall.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In a turbofan the nozzle directs the flow below the wing aft of the leading edge, focuses it more and uses guide vanes to stop its rotation, so this effect does not occur. This eliminates the most important factor for deciding to use counter-rotating propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Combine with the fact that most turbofans are not geared, so the whole engine would have to be mirrored, which would complicate maintenance a lot more than just having mirrored gearboxes and propellers does for turboprops.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-07T10:01:09.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24195" PostTypeId="2" ParentId="24190" CreationDate="2016-01-07T11:42:30.067" Score="10" Body="&lt;p&gt;The concept of lift force per unit span comes from &lt;a href=&quot;https://en.wikipedia.org/wiki/Potential_flow&quot;&gt;potential flow theory&lt;/a&gt;. It will need some background information to explain what it means, so bear with me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the early years of flight, electricity was new and exciting, and it just happened that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Biot%E2%80%93Savart_law&quot;&gt;equations which could calculate the strength of an electromagnetic field&lt;/a&gt; worked equally well when calculating the local flow change effected by a wing. What is the electrical current in a wire became the vorticity in a vortex, and the strength and orientation of the induced magnetic field were equivalent to the induced flow changes. So the vocabulary of electricity was copied over to aerodynamics, just like brain research used vocabulary from computer science when that was a hot topic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we are left with abstract concepts like induced drag or lift per unit span. It would be so much more descriptive to use proper names, but the authors of technical books learned it that way and are much too lazy to explain aerodynamics any better. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://instructional1.calstatela.edu/cwu/me408/Slides/PotentialFlow/PotentialFlow.htm&quot;&gt;potential flow theory&lt;/a&gt;, you have sources, sinks and vortices. Sources and sinks are used to generate the displacement effect of a physical body moving through air, and vortices are used to explain why wings bend the flow and create lift. In order to calculate the lift force $L$ of a single vortex in two-dimensional flow, the circulation strength $\Gamma$ of the vortex is multiplied by the airspeed $u_{\infty}$ and air density $\rho$. You will find an equation like $L = -\Gamma\cdot u_{\infty}\cdot\rho$ in many treatises about numerical aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To expand that into the third dimension (and, consequently, into reality), you need to add something measured in spanwise direction - but you have already lift, and adding the third dimension would give a moment (lift times distance) where only lift would make sense. Therefore, this two-dimensional lift is now called &quot;lift per unit of span&quot; so there is still space for a third dimension where two-dimensional flow did already produce lift (counter to any sound intuition).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no, this is never constant over span. In all cases the vorticity is gradually reduced towards the tips, or explained in a better way, the suction force acting on the wing is gradually reduced when you approach the tips because when the wing ends, nothing can prevent the air from flowing from the high-pressure region below to the low-pressure region on the upper surface of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the potential flow mentioned above is the mathematical way of looking at aircraft, lift coefficients are the engineer's way of expressing things. From tests it was soon clear that the lift force of a wing scales with the dynamic pressure $q$ of the flow, that is the product of air density and the &lt;strong&gt;square&lt;/strong&gt; of airspeed: $q = \frac{\rho}{2}\cdot v^2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next observation of engineers was that lift also scales with wing area $S$. To make the lifting force independent of wing size and dynamic pressure, they stripped both from the lift (physical unit of Kilopond, Newton or pound-force) so they arrived at a dimensionless figure which they called lift coefficient $c_L$. Doing so made it much easier to compare measurements or scale up known designs for the next, better design. The lift equation now becomes $L = c_L\cdot S\cdot\frac{\rho}{2}\cdot v^2$&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-07T12:54:56.333" LastActivityDate="2016-01-07T12:54:56.333" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24196" PostTypeId="2" ParentId="24180" CreationDate="2016-01-07T12:52:26.223" Score="6" Body="&lt;p&gt;Your thrust equation is only valid for the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;static case&lt;/a&gt; (initial speed at infinite distance from the propeller is zero), and neglects the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383#15383&quot;&gt;propeller's efficiency&lt;/a&gt;. For the flight case, I recommend to make a bold assumption for propeller efficiency and to assume that most power will be converted to thrust:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$T = \frac{P}{v}\cdot\eta_{Prop}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A large, slowly turning propeller will have an efficiency approaching 90%, while a small, fast-spinning one will only reach 70%. If operated outside of its design speed, efficiency might even become negative. If you look for an upper boundary of thrust, the equation above sans efficiency will do nicely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the maximum lift answer you should expand your drag coefficient a little, as recommended already &lt;a href=&quot;https://aviation.stackexchange.com/questions/21390/i-need-the-most-simple-plane-lift-equation-that-gives-realistic-solutions/21432?s=1%7C0.2034#21432&quot;&gt;in this answer&lt;/a&gt;. $$c_D = c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you can equate drag and thrust to get: $$P\cdot\eta_{Prop} = \left(c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}\right)\cdot S\cdot\frac{\rho}{2}\cdot v^3$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and solve for lift: $$L = c_L\cdot S\cdot\frac{\rho}{2}\cdot v^2 = \sqrt{\pi\cdot AR\cdot\epsilon\cdot\left(\frac{P}{v}\cdot\eta_{Prop} - c_{D0}\cdot S\cdot\frac{\rho}{2}\cdot v^2\right)}\cdot\sqrt{S\cdot\frac{\rho}{2}\cdot v^2}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/questions/23929/lift-to-drag-ratio-for-max-dwell-time/23944#23944&quot;&gt;minimum power is consumed when the ratio $\frac{c_L^3}{c_D^2}$ reaches its maximum&lt;/a&gt;. Expressed differently, this means that $$c_L = \sqrt{3\cdot\pi\cdot AR\cdot\epsilon\cdot c_{D0}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plugging that back into the lift equation I leave as an exercise to the reader.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the answer really depends on the aerodynamic quality of your airfoil. The best you can reach with regular airfoils is a $c_L$ between 1.5 and 1.8, depending on Reynolds number. With slotted flaps this can be doubled, but $c_{D0}$ will go up substantially, so the best ratio $\frac{c_L^3}{c_D^2}$ can be gained with a clean airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nomenclature:&lt;br&gt;&#xA;    $c_L \:\:\:$ lift coefficient (normally between 0 and 1.5)&lt;br&gt;&#xA;    $S \:\:\:\:\:$ Wing surface area&lt;br&gt;&#xA;    $\pi \:\:\:\:\:$  3.14159$\dots$&lt;br&gt;&#xA;    $AR \:\:$  aspect ratio of the wing (ratio of span to mean chord)&lt;br&gt;&#xA;    $\epsilon \:\:\:\:\:$  the wing's Oswald factor (use 0.8 when in doubt)&lt;br&gt;&#xA;    $c_{D0} \:$  zero-lift drag coefficient (use 0.02 when in doubt and 0.03 with a fixed gear)&lt;br&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-07T12:52:26.223" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24197" PostTypeId="2" ParentId="9995" CreationDate="2016-01-07T16:54:40.153" Score="0" Body="&lt;p&gt;From a little search on the net I have found this book: &lt;a href=&quot;https://www.crcpress.com/Developing-Safety-Critical-Software-A-Practical-Guide-for-Aviation-Software/Rierson/9781439813683&quot; rel=&quot;nofollow&quot;&gt;Developing Safety Critical Software: A practical guide fro Aviation Software - Rierson&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12924" LastEditorDisplayName="user12485" LastEditDate="2016-01-08T15:25:55.253" LastActivityDate="2016-01-08T15:25:55.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24198" PostTypeId="2" ParentId="24180" CreationDate="2016-01-07T17:52:29.400" Score="4" Body="&lt;p&gt;Try to write down  step by step how did you get your first formula for &lt;span class=&quot;math-container&quot;&gt;$Lift_{max}$&lt;/span&gt;. Check not only the math but also the physical meaning of each formula and you'll probably find the error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to calculate the maximum possible lift of an airplane for a given geometry you need to know its lift and drag polars as you wrote in the second update.&#xA;Starting with the lift formula in the second update,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$L=\sqrt[3]{\frac{S\rho P^2}{2}\cdot \frac{C_L^3}{C_D^2}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and assuming a quadratic function for the drag,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$C_D=C_{D0}+k \cdot C_L^2$$&lt;/span&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;we can maximize L:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{\partial L}{\partial C_L}=0 \implies \frac{\partial}{\partial C_L}(\frac{C_L^3}{(C_{D0}+k \cdot C_L^2)^2})=0 \implies C_{L,Lmax}=\sqrt{\frac{3C_{D0}}{k}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Substituting &lt;span class=&quot;math-container&quot;&gt;$C_L$&lt;/span&gt; with your calculated &lt;span class=&quot;math-container&quot;&gt;$C_{L,Lmax}$&lt;/span&gt; we get an expression for the maximum lift:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$L_{max}=\frac{1}{2}\cdot \sqrt{\frac{3}{k}}\cdot \sqrt[3]{\frac{P_{t}^2\eta^2\rho S}{4 \sqrt{C_{D0}}}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also substituted &lt;span class=&quot;math-container&quot;&gt;$P=P_{t}\cdot \eta$&lt;/span&gt;. &lt;span class=&quot;math-container&quot;&gt;$\eta$&lt;/span&gt; is the thrust efficiency due to losses in the gear, propeller,...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now lets see if it makes qualitatively sense:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\downarrow k$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$\downarrow C_{D0} \implies \uparrow L_{max}$&lt;/span&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\uparrow P_t$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$\eta \implies \uparrow L_{max}$&lt;/span&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This seems to be OK. Now let us calculate some values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using &lt;span class=&quot;math-container&quot;&gt;$T\cdot V=\eta P_t$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$T=D=C_D\frac{\rho}{2}V^2$&lt;/span&gt; we get the velocity we are flying at:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$V=\sqrt[3]{\frac{2P_t\eta}{C_D S \rho}}\\&#xA;\implies V_{Lmax}=\frac{1}{\sqrt[3]{2}}\cdot\sqrt[3]{\frac{P_t\eta}{C_{D0} S \rho}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparision we can also calculate this values for &lt;span class=&quot;math-container&quot;&gt;$L/D_{max}$&lt;/span&gt;, the best glide point:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{\partial L/D}{\partial C_L}=0 \implies \frac{\partial}{\partial C_L}(\frac{C_L}{C_{D0}+k \cdot C_L^2})=0 \implies C_{L/Dmax}=\sqrt{\frac{C_{D0}}{k}} \\&#xA;\implies V_{L/Dmax}=\sqrt[3]{\frac{P_t\eta}{C_{D0} S \rho}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The relationship between the velocities at the best glide and maximum lift point is:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\frac{V_{Lmax}}{V_{L/Dmax}}=\frac{1}{\sqrt[3]{2}}\approx 0.79$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we look at a Cessna 172 we get:&#xA; &lt;span class=&quot;math-container&quot;&gt;$$\frac{V_x}{V_{bg}}\approx \frac{60 KCAS}{73 KCAS}=0.82$$&lt;/span&gt;&#xA;This is close to the theoretical value we had calculated. (I have assumed that flying with best climb angle speed is also flying with maximum lift.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RlCPs.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6UU3a.gif&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;(source: &lt;a href=&quot;http://www.allstar.fiu.edu/aero/images/e4low.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;fiu.edu&lt;/a&gt;)&lt;/sub&gt;&lt;br&gt;&#xA;Drag, and thrust of a Cessna 172. Picture &lt;a href=&quot;https://i.stack.imgur.com/6UU3a.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I do not have exact values for the Cessna, for &lt;span class=&quot;math-container&quot;&gt;$\eta=0.4$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$k=0.04$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$C_{D0}=0.03$&lt;/span&gt; at sea level I get &lt;span class=&quot;math-container&quot;&gt;$L_{max}\approx 17600 N$&lt;/span&gt;, which is also a plausible result. Therefore I suppose that the formula for &lt;span class=&quot;math-container&quot;&gt;$L_{max}$&lt;/span&gt; is correct.&lt;/p&gt;&#xA;" OwnerUserId="8749" LastEditorUserId="8282" LastEditDate="2019-04-14T19:33:33.903" LastActivityDate="2019-04-14T19:33:33.903" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24199" PostTypeId="1" AcceptedAnswerId="24200" CreationDate="2016-01-07T20:33:21.590" Score="-2" ViewCount="6968" Body="&lt;p&gt;Other posts didn't answer my question. In A&amp;amp;P school months ago they told us the difference and can't find where I wrote this down. One of them was used to find engine time and the other was used for aircraft total time.&lt;/p&gt;&#xA;" OwnerUserId="12677" LastEditorUserId="1696" LastEditDate="2016-01-07T20:49:42.307" LastActivityDate="2016-01-08T15:28:22.080" Title="Hobbs vs Tach time?" Tags="&lt;aircraft-maintenance&gt;&lt;engine&gt;&lt;time&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-01-07T21:12:21.653" ContentLicense="CC BY-SA 3.0" />
  <row Id="24200" PostTypeId="2" ParentId="24199" CreationDate="2016-01-07T20:49:30.957" Score="0" Body="&lt;p&gt;Generally the engine time is measured using the Tach (and is what the engine is serviced based on) while the airframe time is measured off the hobbs meter. This is based on the idea that the hobbs is running when then plane is &quot;on&quot; (usually when oil pressure is present) but the tach time measures engine wear time. In theory the engine wears slower at a lower RPM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for maintenance this should be elaborated on a bit since most people actually measure this incorrectly sometimes. Tach time is always running however it does not always run at a 1 Tach Hour = 1 Clock Hour rate. Generally the tach timer is set up to run 1 Tach Hour = 1 Clock Hour at 70% power (or some other often used cruise power). Any RPMs below that will run the tach timer slower and any above it will run it faster. Tach time is generally accepted for engine service since it directly measures engine time (it actually measures RPM count) but for service on the rest of the airframe there are a few options. When it comes to a Hobbs meter there are various ways they can be connected. I was always taught it was based on oil pressure however some planes seem to have it wired to the master switch and more importantly others are wired to a squat switch on the gear. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=b74d28700ee95496dc339ae5ed491fa6&amp;amp;mc=true&amp;amp;node=se14.1.1_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;The FAA defines Time In Service as&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Time in service&lt;/em&gt;, with respect to maintenance time records, means the&#xA;  time from the moment an aircraft leaves the surface of the earth until&#xA;  it touches it at the next point of landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=3efaad1b0a259d4e48f1150a34d1aa77&amp;amp;rgn=div5&amp;amp;view=text&amp;amp;node=14:2.0.1.3.10&amp;amp;idno=14#se14.2.91_1401&quot; rel=&quot;nofollow&quot;&gt;Lets take the 100 hour inspection&lt;/a&gt; which is required after 100 hours of &lt;em&gt;Time In Service&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Except as provided in paragraph (c) of this section, no person may&#xA;  operate an aircraft carrying any person (other than a crewmember) for&#xA;  hire, and no person may give flight instruction for hire in an&#xA;  aircraft which that person provides, unless within the preceding &lt;strong&gt;100&#xA;  hours of time in service&lt;/strong&gt; the aircraft has received an annual or&#xA;  100-hour inspection and been approved for return to service in&#xA;  accordance with part 43 of this chapter or has received an inspection&#xA;  for the issuance of an airworthiness certificate in accordance with&#xA;  part 21 of this chapter. The 100-hour limitation may be exceeded by&#xA;  not more than 10 hours while en route to reach a place where the&#xA;  inspection can be done. The excess time used to reach a place where&#xA;  the inspection can be done must be included in computing the next 10&lt;strong&gt;0&#xA;  hours of time in service&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As such a hobbs meter connected to a squat switch would actually be the most representative of &lt;em&gt;Time In Service&lt;/em&gt; which is when hourly maintenance needs to be performed. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-08T15:28:22.080" LastActivityDate="2016-01-08T15:28:22.080" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24201" PostTypeId="1" AcceptedAnswerId="24207" CreationDate="2016-01-07T21:34:41.833" Score="3" ViewCount="1299" Body="&lt;p&gt;Certain aircraft like the A318 are able to do steep approaches for landing. What are the limits (Angle of descent, airspeed, and the like) for this type of landing?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="19" LastEditDate="2016-06-24T10:56:18.003" LastActivityDate="2016-06-24T10:56:18.003" Title="What are the limitations on a steep approach?" Tags="&lt;airliner&gt;&lt;landing&gt;&lt;approach&gt;&lt;aircraft-limitations&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24202" PostTypeId="1" AcceptedAnswerId="24210" CreationDate="2016-01-07T22:11:21.870" Score="6" ViewCount="2234" Body="&lt;p&gt;How can I make sure my aircraft is equipped with a mode C transponder?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;======================&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a transponder has an &lt;strong&gt;ALT&lt;/strong&gt; button does that mean that the aircraft is equipped with MODE C?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/H98uz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H98uz.jpg&quot; alt=&quot;TRANSPODER&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12668" LastEditorUserId="12720" LastEditDate="2016-01-08T02:50:42.303" LastActivityDate="2016-01-08T02:59:13.463" Title="How can I ensure that I have a mode C transponder?" Tags="&lt;transponder&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24203" PostTypeId="1" AcceptedAnswerId="24206" CreationDate="2016-01-07T23:43:41.400" Score="30" ViewCount="4663" Body="&lt;p&gt;The Boeing 737 next generation models (700,800,900ER) all have the same wingspan at 117ft 5 in. Why doesn't the wingspan increase with bigger and longer models? With the 737-900 wouldn't you need a longer wingspan than the 737-700 because of the extra weight you would be carrying and you need more lift to support that extra weight.&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="22726" LastEditDate="2020-07-26T00:44:14.593" LastActivityDate="2020-07-26T00:44:14.593" Title="Why isn't the wing span of a certain airliner longer with the longer fuselage versions?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;boeing-737&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24204" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T00:50:20.247" Score="9" Body="&lt;p&gt;It is correct that more lift is required to lift the extra weight of the larger variant. This could be achieved with a bigger wing, but also by flying faster or at a higher angle of attack or both. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The whole point of introducing aircraft families like the 737 lies in covering a big market segment with as many common aircraft parts as possible (i.e. reducing development and stock cost and realising savings through commonality). Changing the wing for each model would negate that purpose, as the wing is one of the more expensive parts to be designed on an aircraft. Additionally, it would make in-service maintenance and repair more burdensome, as fleet commonality would be reduced.&lt;/p&gt;&#xA;" OwnerUserId="10025" LastActivityDate="2016-01-08T00:50:20.247" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24205" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T00:58:33.927" Score="31" Body="&lt;p&gt;There are two main reasons:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;It is easier to plug in a fuselage section than a (swept back) wing section. If you notice, one thing that has been kept constant across models is the fuselage cross section. Basically, the manufacturer can make another fuselage cross section and add it to the exiting ones.&lt;/p&gt;&#xA;&lt;p&gt;If a wing section is added, on the other hand, the aircraft characteristics will change appreciably, in addition to the difficulty in doing so. If you are adding wing section, quite a lot of additional modifications have to be made (like control surfaces, etc.) which will increase cost, eliminating any cost savings the manufacturer could've had by using common parts across models.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The next, perhaps more important reason for this from airline viewpoint is that it will change the aircraft design group. The following table is from the FAA &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=4&amp;amp;ved=0ahUKEwijkOn--pjKAhWBS44KHVT8C0oQFggzMAM&amp;amp;url=http%3A%2F%2Fwww.faa.gov%2FdocumentLibrary%2Fmedia%2F150-5300-13A-ch1-interactive.pdf&amp;amp;usg=AFQjCNER2iF2rRjH_LN1e0lkGEmiLwd-rQ&amp;amp;bvm=bv.110151844,d.c2E&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5300-13 Airport Design&lt;/a&gt; (The ICAO definitions are more or less the same):&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lrix2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lrix2.png&quot; alt=&quot;ADG&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from FAA AC 150/5300-13 Airport Design&lt;/p&gt;&#xA;&lt;p&gt;For example, the Boeing 737 and Airbus A320 have wingspans at the limit of the design group III (B737 has 117 ft 10 in while A320 has 117 ft 5 in with sharklets). Any increase will change the ADG, which will restrict the number of airports that the aircraft can be operated from, which the airlines won't like.&lt;/p&gt;&#xA;&lt;p&gt;For example, when the 747-8 wingspan was increased, the aircraft category was changed (from ICAO category E to F, equivalent to V to VI) and compatibility studies had to be carried out to permit operations in airports were 747-400s are already in operation.&lt;/p&gt;&#xA;&lt;p&gt;The airlines are perfectly happy to use different operational procedures or sacrifice some other characteristics (like range- for e.g. B737 MAX range drops around 200 miles between MAX 7 and MAX 9; aircraft rarely operate those distances anyway) for having the same aircraft operate in a large number of airports and reduce maintenance burden by having common parts across models.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-10T13:01:23.107" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24206" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T01:01:54.647" Score="23" Body="&lt;p&gt;Short answer: &lt;strong&gt;They only need to develop, build and maintain one type of wing. And there's no reason not to do it.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That, however, leads to the question: &lt;strong&gt;How does it affect performance?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the formula for aerodynamic lift we see there are generally 4 ways to increase a wing's lift:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Increase the angle of attack&lt;/li&gt;&#xA;&lt;li&gt;Increase the wing area&lt;/li&gt;&#xA;&lt;li&gt;Increase speed&lt;/li&gt;&#xA;&lt;li&gt;Increase air density&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Angle of attack&lt;/strong&gt;&lt;br&gt;&#xA;The angle of attack is what defines our aircraft's state, like stall, best cruise, etc.. So we can take it as fixed for a given situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wing area&lt;/strong&gt;&lt;br&gt;&#xA;As you suggested, we could increase the wing's span or depth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Speed&lt;/strong&gt;&lt;br&gt;&#xA;Lift goes with speed squared. To cope with the additional weight of the larger aircraft, we need to increase airspeed for a given situation by the &lt;strong&gt;square root of the load factor&lt;/strong&gt;. Let's say the larger aircraft is &lt;strong&gt;1.5&lt;/strong&gt; times as heavy, all speeds scale with  &lt;strong&gt;sqrt(1.5) = 1.22&lt;/strong&gt;. So all characteristic speeds like stall speed, best climb speed, best cruise speed, etc. 1.22-fold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Air density&lt;/strong&gt;&lt;br&gt;&#xA;Well, we can't change air density. We can, however, fly in denser air, i.e. lower. To put it the other way round, the heavier aircraft suffers from a &lt;strong&gt;lower service ceiling&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;&lt;br&gt;&#xA;Given the same wing, the heavier aircraft performs worse in terms of service ceiling, short take of and landing, but better when it comes to cruising fast.&lt;/p&gt;&#xA;" OwnerUserId="12930" LastEditorUserId="12930" LastEditDate="2016-01-08T01:47:53.173" LastActivityDate="2016-01-08T01:47:53.173" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24207" PostTypeId="2" ParentId="24201" CreationDate="2016-01-08T01:17:25.050" Score="9" Body="&lt;p&gt;&lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjfgpvZg5nKAhVFRI4KHXFgC-4QFggcMAA&amp;amp;url=http%3A%2F%2Fwww.dream-air.ru%2Fnew%2Fpilotam%2F13_steep_approach.pdf&amp;amp;usg=AFQjCNFwHOLG3a5iheQ70Lbvypgd6VT42A&quot; rel=&quot;noreferrer&quot;&gt;This presentation&lt;/a&gt; gives the following limitations for A318 steep approaches:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Maximum authorised Flight Path Angle: -5.5°&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;MLW unchanged (57.5t)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;FWD and AFT CG limits unchanged&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Maximum altitude for landing: 2000ft&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tailwind limit for landing: 5Kt&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Crosswind limit for landing: 26Kt gust included&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;AUTOLAND is not allowed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CATII and CATIII are not allowed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;All engines operative only&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-08T01:17:25.050" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24208" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T01:44:12.193" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;With the 737-900 wouldn't you need a longer wingspan than the 737-700 because of the extra weight you would be carrying and you need more lift to support that extra weight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You would, if the 737-700's wingspan was designed at the design limits for the 737-700's fuselage. But it isn't. Instead, the entire family's wingspan is designed at the design limits for the &lt;em&gt;largest&lt;/em&gt; member of the family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, we could rephrase your question as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aren't the 737-900's wings too small?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the answer is: no, the 737-700's wings are too large!&lt;/p&gt;&#xA;" OwnerUserId="3721" LastActivityDate="2016-01-08T01:44:12.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24210" PostTypeId="2" ParentId="24202" CreationDate="2016-01-08T02:52:10.763" Score="7" Body="&lt;p&gt;For any aircraft you should check the accompanying POH for a full equipment list of what the plane has been outfitted with. Likewise you should be alert for any place cards noting defective or inoperative equipment. You should also check the aircrafts logs to make sure the &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Equipment/Transponder-Requirements&quot;&gt;transponder&lt;/a&gt; has been properly inspected according to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.413&quot;&gt;§ 91.413 ATC transponder tests and inspections&lt;/a&gt; and that it is operable. Just because you have one does not mean its legal to fly with. A transponder capable of Mode-C (altitude encoding) needs to either be connected to an altitude encoding altimeter or a &lt;a href=&quot;http://www.bennettavionics.com/encoder.html&quot;&gt;blind encoder&lt;/a&gt; to report altitude. You should be able to find this out in the POH, if its not connected to one of these two units it will behave like a Mode-A transponder. You can find a  &lt;a href=&quot;http://www.askacfi.com/8503/is-a-transponder-of-any-value-if-it-isnt-linked-to-an-encoding-altimeter.htm&quot;&gt;discussion on the various setups here&lt;/a&gt;. If you are really curious about how &lt;a href=&quot;http://www.airsport-corp.com/modec.htm&quot;&gt;Mode-A/Mode-C communication works this is a pretty good read&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specific to the Garmin unit you have pictured you can get it to display the aircrafts altitude by pressing the &quot;func&quot; button (pressure altitude that is) and compare with your altimeter. If the unit has a readout it then an pressure unit can be assumed to be connected. &lt;em&gt;NOTE: This is not an official test by any means.&lt;/em&gt;     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-08T02:59:13.463" LastActivityDate="2016-01-08T02:59:13.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24211" PostTypeId="1" AcceptedAnswerId="24230" CreationDate="2016-01-08T03:30:21.103" Score="13" ViewCount="1361" Body="&lt;p&gt;I'm doing a research with FIR Ho Chi Minh (formerly named FIR Saigon).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read a document which said:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;During the Fall of Saigon, ICAO, in 28th of April 1975, had divided FIR Saigon into 3 AOR: Bangkok, Singapore and Hongkong, then they gave these AOR to the corresponded FIR.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the 7th of December, 1994, ICAO sent AOR Bangkok and AOR Singapore back to FIR Ho-Chi-Minh.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the 1st of November, 2001, ICAO gave part of AOR Hongkong to FIR Ho-Chi-Minh, and created AOR Sanya from the remained part of AOR Hongkong.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the 8th of June, 2006, ICAO changed AOR Sanya to FIR Sanya&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I managed to search those old FIR maps in the internet but no luck for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, I would like to find out all historical FIR maps to make a comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is impossible to find all FIR maps, old FIR maps of South East Asia FIR is greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="12830" LastEditorUserId="12830" LastEditDate="2016-01-09T04:22:40.373" LastActivityDate="2018-04-03T20:15:53.037" Title="Where can I find old (historical) FIR map?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;icao&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24212" PostTypeId="2" ParentId="24193" CreationDate="2016-01-08T04:26:29.693" Score="6" Body="&lt;p&gt;I think the reason has more to do with the Propeller (P) factor and the rudder corrections required to over come it. This effect does not arise from gyroscopic effects - it is an aerodynamic phenomenon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low airspeed and high angle of attack flight causes the blade descending on one side of the propeller disk to see a lower angle of attack than it sees when ascending on the opposite side of the propeller disk. The blade on the side seeing the higher angle of attack generates more thrust creating a torque about a roughly vertical axis. This torque twists the aircraft in yaw and must be resisted by a force created by a rudder deflection if steady flight is to be maintained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High power propellers will produce a proportionately high torque about the vertical axis at high angles of attack and low airspeed. Thus, high power aircraft will require a significant rudder input to overcome this torque and keep the aircraft aligned with the relative airflow or the runway or to keep it traveling through the air in a straight line and on a constant heading. When operating at high power and low airspeed the required rudder input can be very considerable. A long climb can give a pilot one very tired leg. Also, on applying power by increasing engine rpm the pilot must also make a coordinated rudder input as the amount of rudder input depends on the speed of the propeller. Counter rotating propellers eliminate this P torque and any corrective rudder input requirement for changes in propeller rpm or aircraft angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, pitching and yawing an aircraft can change the angle of entry of air into the propeller disk. Once again, this can cause uneven thrust around the propeller disk creating a torque on the aircraft around some axis other than the one the pilot intended. This torque then requires yet another coordinated input from the pilot to maintain the desired flight path. The axes controls are said to be coupled and pilot inputs become complicated and non-obvious increasing pilot work load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, coupling of two axes in this way can cause an aircraft to continuously oscillate about the pitch and yaw axes and these oscillations can be out of phase causing the aircraft to continually vary pitch and yaw creating an uncomfortable sensation for those on board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Counter rotating propellers can eliminate all the effects of P factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inlet ducts of jet engines direct the airflow into the engine and the turbine disks and align it with the turbine shaft axis perpendicular to the plane of the blade disk. &#xA;As a result, P factor does not come into play here, jets do not have the problems caused by P factor, and jets do not need counter rotation to overcome it.&lt;/p&gt;&#xA;" OwnerUserId="12931" LastActivityDate="2016-01-08T04:26:29.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24215" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T08:31:48.110" Score="27" Body="&lt;p&gt;A wing is very hard to expand, unlike a fuselage when it has a cylindrical mid section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wings need to be dimensioned to not break when loaded with the maximum conceivable air loads in operation. These are reached when the aircraft flies into a strong updraft at high speed, and speed limits must be obeyed in gusty weather to make sure the wings stay intact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If some area is added at the tips, it will create a lot of bending moment (lift force times lever arm) for relatively little lift. This bending moment is responsible for the stresses at the wing root and must, therefore, be limited so the wing will not break off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to produce more lift, only the flaps are modified. Compare the two pictures below: The upper shows the flaps of an A319 and the lower shows those of an A321:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VH9dD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VH9dD.jpg&quot; alt=&quot;A319 flaps in landing configuration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A319 flaps in landing configuration (picture &lt;a href=&quot;http://www.airliners.net/photo/Northwest-Airlines/Airbus-A319-114/1155164/L/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fzl2t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fzl2t.jpg&quot; alt=&quot;A321 flaps in approach configuration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A321 flaps in approach configuration (picture &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/0/1/9/0641910.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the A319 flap is single-slotted, the A321 uses a second flap segment with an additional slot to eke out a little more lift from the same planform. It also has a deeper flap, so wing chord is slightly increased. This helps to make the landing speeds of both aircraft similar, while the &lt;a href=&quot;http://www.flugzeuginfo.net/acdata_php/acdata_a321_en.php&quot; rel=&quot;noreferrer&quot;&gt;maximum landing weight of the A321&lt;/a&gt; is 27.5% higher than &lt;a href=&quot;http://www.flugzeuginfo.net/acdata_php/acdata_a319_en.php&quot; rel=&quot;noreferrer&quot;&gt;that of the A319&lt;/a&gt;. For similar take-off performance, more powerful engines are selected, but for landing performance the wing needs to create more lift. In cruise the wing will simply be operated at a higher lift coefficient. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only for the A340-500/600 series was the wing area increased by inserting a triangular mid section into the airfoil, so both &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/143532&quot; rel=&quot;noreferrer&quot;&gt;chord and span could be increased&lt;/a&gt; over that of the A340-200/300. This was possible due to the geometry of modern supercritical airfoils, but is a very rare occurrence. Besides allowing the wing to create more lift, this expanded the internal fuel volume by 50%, so the A340-500 became the world's longest range airliner when it was introduced in 2002. It also increased the root structure and its maximum bending moment, so the wing span could be extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QHLJ5.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QHLJ5.png&quot; alt=&quot;A340 version comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A340 version comparison (own work). Blue is the A340-200, red is the A340-500. Note the wing chord increase while the tail surfaces remained unchanged.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-05-06T20:24:08.663" LastActivityDate="2020-05-06T20:24:08.663" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="24217" PostTypeId="1" AcceptedAnswerId="24218" CreationDate="2016-01-08T11:50:46.667" Score="13" ViewCount="1364" Body="&lt;p&gt;I saw a picture on Twitter after the loss of cabin pressure. I've seen these images many times before, but in this picture, there are some things on strings that I cannot identify. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZxBSa.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZxBSa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11423" LastActivityDate="2016-01-08T14:28:41.100" Title="What are these things on strings after the loss of cabin pressure?" Tags="&lt;safety&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24218" PostTypeId="2" ParentId="24217" CreationDate="2016-01-08T14:20:40.723" Score="17" Body="&lt;p&gt;They are the holders for the oxygen masks, they are packed into the plastic retainers and stored in the overhead, when the masks drop, they fall out of the containers. Not all systems have these retention pieces that I can find, but some do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;black&quot; tubes (actually clear, but look black in the picture) you see are the oxygen mask tubes and the mask itself is dangling from the end of the tube, you can see they have green/red labels on them that signify they are oxygen. The oxygen generator for that group of seats/masks is under the label in the top &quot;HOT HOT&quot;, oxygen systems get very hot when generating oxygen (just ask &lt;a href=&quot;https://en.wikipedia.org/wiki/ValuJet_Flight_592&quot;&gt;ValuJet&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-01-08T14:28:41.100" LastActivityDate="2016-01-08T14:28:41.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24219" PostTypeId="1" AcceptedAnswerId="24225" CreationDate="2016-01-08T19:02:42.963" Score="11" ViewCount="14027" Body="&lt;p&gt;From other answers I've gathered that stall occurs when the air flow separates from the wing surface. And also that this starts at the back of the wing and progresses forward as AOA increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this process not uniform? What causes the buffeting just under the stall AOA? Is it simply the turbulence behind the point of separation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what factors, such as speed, altitude or air density affect the amount of buffeting?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-01-09T01:17:35.530" Title="What causes stall buffeting?" Tags="&lt;wing&gt;&lt;stall&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24220" PostTypeId="2" ParentId="24219" CreationDate="2016-01-08T19:39:47.143" Score="7" Body="&lt;p&gt;&lt;a href=&quot;http://www.experimentalaircraft.info/flight-planning/aircraft-stall-speed.php&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; states it pretty well (better than I can word it). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the angle of attack (AOA) of the wing increases, the point where&#xA;  the airflow separates will move forward and the streamlined airflow&#xA;  will become turbulent and separate from the wing. This turbulent wake&#xA;  then meets the aft fuselage and tail section of the aircraft. This&#xA;  will be felt by the occupants of the aircraft as a rumble or buffet.&#xA;  Not all aircraft have a pronounced buffet, this depends on the size&#xA;  and location of elevator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough you can also induce a stall (and first high speed buffeting) by gong too high and too fast while trying to maintain level flight which will cause the center of lift to move aft along the wing. Basically your stall speed and your critical mach number eventually converge this is known as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Coffin_corner_(aerodynamics)&quot; rel=&quot;nofollow&quot;&gt;coffin corner&lt;/a&gt;. There is a nice &lt;a href=&quot;http://www.pprune.org/tech-log/534954-high-speed-buffet-high-altitude-level-flight-lead-stall.html&quot; rel=&quot;nofollow&quot;&gt;discussion on it here&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="394" LastEditDate="2016-01-08T21:18:30.070" LastActivityDate="2016-01-08T21:18:30.070" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24221" PostTypeId="2" ParentId="16844" CreationDate="2016-01-08T21:23:01.690" Score="2" Body="&lt;p&gt;AOPA has a comprehensive list that answers your question from the medical perspective. The linked resource for each broad category explains the particulars.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical&quot; rel=&quot;nofollow noreferrer&quot;&gt;Health Conditions That May Affect Certification&lt;/a&gt;&lt;/h3&gt;&#xA;&lt;p&gt;In this section, find answers to questions about how a medical&#xA;condition might impact your flying privileges. Information is&#xA;categorized by physiology and includes the relevant medical standards,&#xA;as well as the procedures to follow for recertification, or to obtain&#xA;a special issuance medical certificate.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Bone-and-Joint&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bone and Joint&lt;/a&gt;&lt;/strong&gt;—Includes information on arthritis and musculoskeletal&#xA;conditions.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Cancer&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cancer&lt;/a&gt;&lt;/strong&gt;—Many pilots recover from cancer and regain flying privileges.&#xA;Find out more here.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Ear-Nose-Throat-and-Equilibrium&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ear, Nose, Throat, and Equilibrium&lt;/a&gt;&lt;/strong&gt;—Read the medical standards for&#xA;hearing, as well as information on cochlear implants, Eustachian&#xA;bypass, and motion sickness.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Endocrine-System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Endocrine System&lt;/a&gt;&lt;/strong&gt;—Includes information on diabetes and thyroid&#xA;conditions.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Gastrointestinal&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gastrointestinal&lt;/a&gt;&lt;/strong&gt;—GERD, hepatitis, colitis, Crohn’s disease and more&#xA;are covered here.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Heart-and-Circulatory-System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heart and Circulatory System&lt;/a&gt;&lt;/strong&gt;—Read how to get recertified after having&#xA;heart-related problems.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Immune-System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Immune System&lt;/a&gt;&lt;/strong&gt;—HIV and related conditions are included in this section.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Mental-Health&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mental Health&lt;/a&gt;&lt;/strong&gt;—This section covers ADD/ADHD, depression, psychological&#xA;evaluation, and substance abuse.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Neurological&quot; rel=&quot;nofollow noreferrer&quot;&gt;Neurological (Nervous System)&lt;/a&gt;&lt;/strong&gt;—Read about migraine headaches,&#xA;cerebrovascular disease, and strokes.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Pulmonary&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pulmonary&lt;/a&gt;&lt;/strong&gt;—Read how you can keep your medical certification if you have&#xA;asthma, allergies, or another lung-related condition.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Sleep-Disorders&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sleep Disorders&lt;/a&gt;&lt;/strong&gt;—Find out what you’ll need to do to get your medical&#xA;renewed if you have sleep apnea.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Substance-Abuse&quot; rel=&quot;nofollow noreferrer&quot;&gt;Substance Abuse&lt;/a&gt;&lt;/strong&gt;—Here are the guidelines for certification if you have&#xA;a history of alcohol or drug-related problems.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Urology&quot; rel=&quot;nofollow noreferrer&quot;&gt;Urology (includes kidney)&lt;/a&gt;&lt;/strong&gt;—Read how to be recertified after having&#xA;kidney stones removed, or after a successful kidney transplant.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Vision&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vision&lt;/a&gt;&lt;/strong&gt;—Color vision, glaucoma, and LASIK surgery are all covered here.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-08T23:55:29.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24222" PostTypeId="2" ParentId="17052" CreationDate="2016-01-08T22:05:53.060" Score="5" Body="&lt;p&gt;What you describe in your example at best is a corporate flight department that operates your plane (with the proper legal arrangements) and you fly the plane.  You need a commercial certificate for this -- you won't be able to argue your company salary isn't in some part compensation for the flying.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At worst, you operate the plane and are a part 135 carrier which requires an operating certificate under 14 CFR 119 and compliance with 14 CFR 135.  Of note you'll need a commercial certificate and 500 hours total time to fly the plane in VFR conditions and you'll need an instrument rating for the commercial certificate to be useful.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can fly yourself to and from meetings, but do not offer to do this for co-workers and do not feed the idea to your boss so that he proposes it.  Whatever you do, join AOPA and consult their lawyers to get a real interpretation of how the regs apply to your possible arrangements and if there is still grey area, consult the FSDO for their opinion.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-08T22:05:53.060" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24223" PostTypeId="2" ParentId="24203" CreationDate="2016-01-08T23:24:51.217" Score="11" Body="&lt;p&gt;One point that hasn't been mentioned yet:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fully loaded and empty weights of an aircraft can differ greatly. For a typical airliner the takeoff weight can be between about 25% and 45% fuel &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_fraction&quot;&gt;https://en.wikipedia.org/wiki/Fuel_fraction&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore it is perfectly possible for a long fuselage variant used on short haul routes and a short fuselage variant on used on long haul routes (requiring a lot more fuel) to have exactly the same takeoff weight, and therefore wing loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, a given wing design has a maximum allowable loading, but the way that can be distributed between % plane + % fuel + % payload can vary significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, it's certainly true that due to standardization, there are many planes out there with overdesigned wings. You can see the A380 wings have quite a large area compared with the rest of the plane. They were designed with the idea of stretching the plane later, but there hasn't been much interest in a stretched version yet.&lt;/p&gt;&#xA;" OwnerUserId="1952" LastActivityDate="2016-01-08T23:24:51.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24225" PostTypeId="2" ParentId="24219" CreationDate="2016-01-09T01:17:35.530" Score="6" Body="&lt;p&gt;Not all stalls start from the trailing edge and progresses forward. In general, &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=7&amp;amp;ved=0ahUKEwiVroGcuJvKAhUJJI4KHQvVDGsQFgg1MAY&amp;amp;url=http%3A%2F%2Fnaca.central.cranfield.ac.uk%2Freports%2F1951%2Fnaca-tn-2502.pdf&amp;amp;usg=AFQjCNFdDImh38AMYMfPXqlixd8x69UtBQ&amp;amp;bvm=bv.111396085,d.c2E&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;three types of stall are described&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Trailing edge stall- This is the preferred stall characteristic; The turbulent separation point moves forward from the trailing edge with increasing angle of attack. usually found in airfoil sections with thickness ratios 0.15 and greater.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Leading edge stall- The flow separates abruptly from the leading edge without subsequent reattachment; usually found in airfoils with thickness ratios between 0.09 and 0.15.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thin airfoil stall- Found in airfoils with small thickness (&amp;lt; 0.09), the separation occurs at the leading edge and the flow reattaches at a point which then moves progressively rearward with increase in angle of attack.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Buffet is a kind of &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_16/vibration_story.html&quot; rel=&quot;noreferrer&quot;&gt;vibration caused by aerodynamic excitation&lt;/a&gt;, usually associated with separated (or turbulent) airflow. As the aircraft approaches stall, the airflow over the wing becomes turbulent and if it flows across the horizontal stabilizer, buffeting may occur. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether low speed (stall) buffet happens or not depends on the aircraft characteristics; for example, the stall starts from the root in case of straight wings and the stabilizer is affected by the turbulent airflow before the outer wing stalls- this can be used by the pilot to take corrective action (as @Ron Beyer points out in his comments). In case of swept wing aircraft, the stall progresses the other way around- from tips to rot and it will be difficult for the pilot to use buffet in any real sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This buffeting can act as a warning for the pilot that the aircraft is approaching stall and he/she has to take corrective action. In aircraft that do not show this behavior, some warning cues, like stick shaker are sometimes incorporated in order to warn the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As density altitude increases, the angle of attack required to produce turbulence at the top of the wing (stall angle) decreases till a point is reached that the high speed buffet (Mach buffet, due to supersonic airflow) and the stall buffet (as already explained) converge. This point is called the coffin corner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4wsIJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4wsIJ.png&quot; alt=&quot;Coffin Corner&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:CoffinCornerU2.png#/media/File:CoffinCornerU2.png&quot; rel=&quot;noreferrer&quot;&gt;CoffinCornerU2&lt;/a&gt;&quot; by Department of Defense - AF (C)-1-1, Flight Manual, Models U-2C and U-2F aircraft. Page 6-11. Licensed under Public Domain via &lt;a href=&quot;//en.wikipedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From FAA Handbook FAA-H-8083-3A:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An airplane’s indicated airspeed decreases in relation to true airspeed as altitude increases. As the indicated airspeed decreases with altitude, it progressively merges with the low speed buffet boundary where prestall buffet occurs for the airplane at a load factor of 1.0 G. The point where the high speed Mach indicated airspeed and low speed buffet boundary indicated airspeed merge is the airplane’s absolute or aerodynamic ceiling. ... the airplane can neither be made to go faster without activating the design stick puller at Mach limit nor can it be made to go slower without activating the stick shaker or stick pusher. This critical area of the airplane’s flight envelope is known as “coffin corner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-09T01:17:35.530" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24226" PostTypeId="1" AcceptedAnswerId="24227" CreationDate="2016-01-09T01:37:44.893" Score="-1" ViewCount="132" Body="&lt;p&gt;My apologies if this is the wrong forum, but I have seen hot questions about drones/quad-copters from here in the past.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I received a quadcopter recently (&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B00MNG37C2&quot; rel=&quot;nofollow noreferrer&quot;&gt;X5C Explorers&lt;/a&gt;), and it has a piece I can not seem to identify online or in the packaging/manual itself.  It is orange, and appears to have a USB port on one end and an slot for possibly an SD card on the other (not too sure to be honest, but the quadcopter has a camera so probably has something to do with that).  Picture included below.  So any idea what this thing is and more importantly, how it should be used?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DfeyE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DfeyE.jpg&quot; alt=&quot;SD card slot?&quot;&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qOzHn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qOzHn.jpg&quot; alt=&quot;USB port?&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12940" LastActivityDate="2016-01-09T02:07:05.297" Title="Just got a quadcopter, and not sure about a piece that came with it" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2016-01-09T02:27:05.470" ContentLicense="CC BY-SA 3.0" />
  <row Id="24227" PostTypeId="2" ParentId="24226" CreationDate="2016-01-09T01:53:02.423" Score="5" Body="&lt;p&gt;This question does not belong in this SE, however this cable is for uploading pictures from the SD Card (Supposedly from your drone camera) to your computer via USB. You just plug the SD Card in the end it belongs in and plug it into a USB port on your computer.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-01-09T02:07:05.297" LastActivityDate="2016-01-09T02:07:05.297" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24228" PostTypeId="1" CreationDate="2016-01-09T06:37:55.057" Score="2" ViewCount="1396" Body="&lt;p&gt;It seems very difficult to find this information on any legitimate sites, so I'm going to ask here. I know nothing about flying, and this wouldn't happen for years to come, but I am curious. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I want to someday go into my backyard, get into my plane, and have  flight to start the morning, then land back in my property (which would obviously have to be quite large).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much, generally speaking, would ALL of the following cost me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-Flight lessons, from complete noob to completely done&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-Small, modest, low-tech, possibly used, two seater personal plane&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-reasonable range for the upkeep costs of a plane (fuel, maintenance, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that this is difficult question to answer, but I'm looking for a very general, rough idea. At least an order of magnitude estimate. &lt;/p&gt;&#xA;" OwnerDisplayName="user12942" LastActivityDate="2016-01-09T17:56:26.007" Title="How much does it cost to fly a plane? INCLUDING lessons, and everything else" Tags="&lt;general-aviation&gt;&lt;cost&gt;&lt;aircraft-ownership&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2016-01-09T13:22:03.013" ContentLicense="CC BY-SA 3.0" />
  <row Id="24229" PostTypeId="2" ParentId="24228" CreationDate="2016-01-09T11:22:46.483" Score="3" Body="&lt;p&gt;As Ben says, it depends a lot on which country you're in: Both due to natural differences in the cost of things (Germany is more expensive than, say, Vietnam for instance) but also because different countries have different requirements for how much experience you need before they hand you a license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But as an example let's go with the USA, based on the prices from my old club in MA:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Going from zero experience to a private pilot license will typically cost you around \$8-9k. A bit less if you learn quickly or a bit more if you need extra practice. If you already bought your own plane then this will be reduced quite a lot. The exat figures will depend on how much time you need with an instructor vs how much time solo but you can, ballpark estimate, halve the cost by using your own aircraft. This only works in some countries, though. Others (including EASA in Europe, I think) require a 'company' aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A  basic plane will cost anywhere between \$15-25,000. The cheapest I've seen recently was just over \$13k but it looked like junk.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel costs around \$6.50 per gallon and you use anywhere from 5-8 gallons per hour, typically. Maintenance depends a lot on the plane, my old flying club used to spend about \$3500/year on each of their Cessna 172s.  You also have insurance on top of that, which is likely to be around \$2.5k&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12234" LastEditorUserId="917" LastEditDate="2016-01-09T17:56:26.007" LastActivityDate="2016-01-09T17:56:26.007" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24230" PostTypeId="2" ParentId="24211" CreationDate="2016-01-09T18:05:24.180" Score="8" Body="&lt;p&gt;The best I can find is a ATC radar screen used in a dated report (appears to be &lt;a href=&quot;http://www.cad.gov.hk/reports/an2000-2001/Chapter03.pdf&quot; rel=&quot;noreferrer&quot;&gt;a report by the Hong Kong Civil Aviation Department in 2000&lt;/a&gt;). It shows the FIR regions and waypoints of near Hong Kong, Hainan island and Vietnam:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BMYnj.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BMYnj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a dated enroute chart of Hong Kong in 1996. I'm not sure if the waypoint names will be useful for your further search:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eF77W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eF77W.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;How I end up with these: for the first one I used keyword &quot;Sanya AOR&quot;. Given the dates you stated in the question, Kai Tak airport was still operational during that time. So I searched for charts of Kai Tak. A full set of charts of the airport would contain an &quot;enroute chart&quot; which lists waypoints. Search engine is Bing.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-01-09T18:05:24.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24231" PostTypeId="1" AcceptedAnswerId="24233" CreationDate="2016-01-10T02:28:02.853" Score="5" ViewCount="1063" Body="&lt;p&gt;In another SE Aviation question about the preferred approach for commercial aviation (Visual vs ILS) there's the following useful explanation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In most ATC facilities, the Tower decides what runway to use, and the&#xA;  approach control calls the type of approach generally on offer(this&#xA;  can vary depending on facilities and how they agree to run things). A&#xA;  pilot can always request a different approach... they might be&#xA;  delayed, sometimes significantly if they insist on something way out&#xA;  of the loop&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm curious what would be examples of a pilot insisting on &quot;something way out&#xA;of the loop&quot;? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/13174/whats-the-preferred-approach-for-a-passenger-jet&quot;&gt;What&amp;#39;s the preferred approach for a passenger jet?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2017-01-30T21:08:19.017" Title="Why would a pilot request an unusual approach/runway to ATC?" Tags="&lt;air-traffic-control&gt;&lt;airliner&gt;&lt;airline-operations&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24232" PostTypeId="2" ParentId="13174" CreationDate="2016-01-10T03:00:05.817" Score="7" Body="&lt;p&gt;Given the caveat that I retired in 1999 and cannot speak for today's pilots, my thinking and the observed preferences of the great majority of the pilots I flew with follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With few exceptions, a visual approach was preferred over an ILS for the simple reason that it's usually quicker, and over time in large aircraft, the fuel savings can be significant for your company. I did know a few pilots, though, that liked to stay in the air longer to increase the size of their paycheck when being paid by the flight hour. I always felt this was unprofessional. A 747-100/200 (my airplane for my final 10 years) burns a lot of fuel, and part of the captain's responsibility is not costing the company money if you don't have to. Also, if you have people in the back making connections, you want to maximize the time they'll have to make those connections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are times, though, even with CAVU conditions, you may want the ILS. For example, I was offered the visual approach one night into Hunter Army Airfield in Savannah, Georgia. It was my first time there, and locating the runway in the maze of lights made it unwise to accept. In fact, I found that airfield so hard to find visually at night, that I continued asking for the ILS until I had been there several times.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if it's clear, but you're going into LAX on a hundred mile final from the east with 15 or more aircraft doing the same, you don't even think about a visual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally I followed the practice of requesting a visual approach when first possible going into familiar airports when the traffic was light and there was time to be saved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were pilots of foreign airlines that would never request a visual. For example, Japan Air and Korean Air going into Anchorage in the early 1990s always requested an ILS. If it wasn't available, they would request a VOR approach. As I understand it, their training, culture, and experience (as explained to me by a JAL check captain) didn't favor being able to just look at a runway and land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a minor point, but to me visual approaches offered more opportunities to play.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-01-10T08:01:23.393" LastActivityDate="2016-01-10T08:01:23.393" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24233" PostTypeId="2" ParentId="24231" CreationDate="2016-01-10T03:30:24.533" Score="11" Body="&lt;p&gt;For currency, airline pilots have to do various approaches every so often to remain current or for the plane to be current (RNAV/ILS Cat II/III approaches). So, every now and then when coming to another airport they could request to shoot that approach instead of the one being used. Sometimes it's a non event (no traffic, or the few other aircraft either fit well before or behind them); other times, it could hinder the flow of operations if they're allowed to do full or certain procedures (various circling to land procedures).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another very common request that falls in this category is to land or depart in the opposite direction of what's being advertised. This in recent years has become more cumbersome for controllers (due to more and new rules implemented), so it's being used less often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes when there's little traffic it's fairly easy to accomplish this kind of arrival or departure. Other times, it becomes a nightmare, and unless it's operationally mandated the pilot will be told, unable opposite direction, due to traffic. When it's operationally needed, then it will be told to hold somewhere to wait until there's space to get them out for departure; or vectored around or put in holding if needing to land opposite direction, and they can be accommodated.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="3313" LastEditDate="2016-01-10T12:58:28.433" LastActivityDate="2016-01-10T12:58:28.433" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24234" PostTypeId="1" CreationDate="2016-01-10T14:07:01.853" Score="5" ViewCount="460" Body="&lt;p&gt;I was recently looking into the KAMRA procedure to fix my reading problem. Then I came across some posts that discourage it as it causes one to see halos in night so particularly bad for pilots. I was wondering if anyone else here has done that that what was his or her experience about it? What are the regulations on this as well?&lt;/p&gt;&#xA;" OwnerUserId="12948" LastEditorUserId="167" LastEditDate="2016-01-13T04:01:44.560" LastActivityDate="2019-10-13T18:17:18.283" Title="What should I know before getting the KAMRA laser eye surgery procedure as a pilot?" Tags="&lt;medical&gt;&lt;night-flying&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24237" PostTypeId="2" ParentId="24234" CreationDate="2016-01-10T15:57:14.993" Score="6" Body="&lt;p&gt;I'm not clear if you are asking about LASIK or KAMRA, &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/et/31-34/rp/&quot; rel=&quot;noreferrer&quot;&gt;the former is accepted by the FAA&lt;/a&gt;, while there is no explicit mention of the latter procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://kamra.com/kamra-inlay/&quot; rel=&quot;noreferrer&quot;&gt;procedure site&lt;/a&gt; itself mentions halos as one of the side effects of the procedure:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The KAMRA inlay procedure may cause blurred vision, difficulties with contrast sensitivity, problems with night vision, double vision, ghost images, glare, halos, and color disturbances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In general, people with such adverse effects and complications are not allowed to serve as airmen:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA expects that airmen will not resume airman duties until ... there are no significant adverse effects or complications (such as halos, rings, haze, impaired night vision and glare), ...  and reviewed by an Examiner or AMCD.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The medical certificate for a person who had undergone such procedures is contingent upon the absense of any side effects affecting vision:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An applicant treated with a refractive procedure may be issued a medical certificate by the Examiner if ... the applicant does not suffer sequela such as; glare intolerance, halos, rings, impaired night vision, or any other complications&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It would be better if you consult a doctor to find out if the procedure is suitable for you and possibility of side effects.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-10T15:57:14.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24238" PostTypeId="1" AcceptedAnswerId="24239" CreationDate="2016-01-10T15:57:44.813" Score="9" ViewCount="1085" Body="&lt;p&gt;For the purposes of airspeed restrictions within airspace, the FAA regulations list the following area description (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c5da463aeef18b9cee56fe93e6e7b124&amp;amp;mc=true&amp;amp;node=se14.2.91_1117&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.117 (C)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an aircraft in &lt;strong&gt;the airspace underlying a Class B airspace area designated for an airport&lt;/strong&gt; [...] at an indicated airspeed of more than 200 knots (230 mph).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Should we understand the described airspace to be any and all airspace underlying a Class B where that specific Class B is designated for an airport? Or, should we understand the described airspace to be any and all airspace designated for an airport (Class C, D, or E) which is underlying a Class B?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there letters of interpretation or other regulations which clarify the grammatical ambiguity of this regulation?&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-11-17T02:30:17.423" LastActivityDate="2018-04-19T20:43:41.667" Title="What is &quot;airspace underlying a Class B airspace area designated for an airport&quot;?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;airspeed&gt;&lt;class-b-airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24239" PostTypeId="2" ParentId="24238" CreationDate="2016-01-10T16:26:54.637" Score="11" Body="&lt;p&gt;Yes, there is &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2015/duncan-afs-1_4%20-%20(2015)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;a legal interpretation&lt;/a&gt; on this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] under  the  express  language  of  the  regulation,  aircraft &#xA;  operating  in  the  airspace  underlying  Class  B  airspace -&#xA;  irrespective  of  whether  the  underlying  airspace  is  controlled &#xA;  or  uncontrolled - may  not  exceed  the  200-knot  speed  limitation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is indeed any and all airspace underlying class B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And note the exception to the rule:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We  note  § &#xA;  91.117  (d)  does  provide  that,  if  the  minimum  safe  airspeed  for  any  particular  operation  is  greater  than  the  maximum &#xA;  speed  prescribed  in  § &#xA;  91.117,  then  an  aircraft  may  be  operated  at  that  minimum  speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2018-04-19T18:08:07.607" LastActivityDate="2018-04-19T18:08:07.607" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24240" PostTypeId="1" AcceptedAnswerId="24241" CreationDate="2016-01-10T16:36:36.493" Score="18" ViewCount="8637" Body="&lt;p&gt;Doing a little doodling on flightradar24.com and Wikipedia, I saw that all the versions on the Boeing 747 except for the -300 version are used. Why is the Boeing 747-300 not used even though it is newer than the -100, -200, and SP versions?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="2923" LastEditDate="2016-01-10T16:56:27.000" LastActivityDate="2020-01-09T20:57:05.630" Title="Why is the Boeing 747-300 not in service anymore?" Tags="&lt;boeing-747&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24241" PostTypeId="2" ParentId="24240" CreationDate="2016-01-10T17:34:56.157" Score="20" Body="&lt;p&gt;The 747-300 was somewhat of a cross between -200 and SP. The -300 was almost same as the -200 except for the increased length of the hump. The -300 was never a success and was soon overshadowed by the -400. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 747SP was the result of a requirement for longer range aircraft. Boeing engineers basically &lt;a href=&quot;http://www.airspacemag.com/how-things-work/how-the-747-got-its-hump-4578877/?no-ist=&amp;amp;page=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;cut around 47' from the 747 fuselage in SP&lt;/a&gt;. However, by the time it flew for the first time, commercial air travel had changed (in no small part due to the high oil prices) and the model never sold as much as Boeing had hoped. However, when it was observed that there were no adverse effects when the rear of the cockpit lined up with the front of the wing, Boeing introduced the 747-300 with increased length of the hump with little else in terms of major change from -200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, just two years after -300 was introduced, Boeing introduced the -400, which was a significant improvement- it eliminated the flight engineer, increased range among others, while retaining the -300's hump (which meant more economy seats). 747-400 is the most successful model of the series, with more than 690 orders. Most airlines jumped straight to the -400, effectively killing the -300.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, the 747-200 production (with over 390 made) ended &lt;em&gt;after&lt;/em&gt; the -300 version (of which only 81 were made). So they are more of contemporaries. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it'll be a stretch to call that the older 747 versions are still in passenger service. 747-100 is &lt;a href=&quot;http://worldairlinenews.com/2014/01/09/iranair-retires-the-last-passenger-boeing-747-100-after-almost-35-years-of-service/&quot; rel=&quot;nofollow noreferrer&quot;&gt;not flown with passengers anymore&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747SP#Current_operators&quot; rel=&quot;nofollow noreferrer&quot;&gt;current operations of 747SP&lt;/a&gt; hardly qualify as passenger service and the most successful of these, the 747-200s are also &lt;a href=&quot;https://aviation.stackexchange.com/questions/9340/how-many-747-200-are-still-in-service&quot;&gt;being slowly phased out&lt;/a&gt;, if you discount the VC-25s flying around with US President (which are slated to be replaced by 747-8s).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-10T23:48:20.853" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24242" PostTypeId="1" CreationDate="2016-01-10T23:20:26.053" Score="15" ViewCount="3372" Body="&lt;p&gt;For an aircraft in a glide, what—if any—is the optimal bank angle to make a given turn while maximizing glide distance and maintaining published best glide speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, at a constant airspeed, which bank angle will produce the greatest turn rate with the smallest loss in altitude. Assume a constant airspeed turn that is already established. I am not asking which bank angle will produce the least reduction in the vertical component of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In envisioning this scenario, I specifically have in mind a single engine aircraft experiencing an engine failure at low altitude. However, the aerodynamic theory may apply to any fixed wing scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit: let me emphasize that this question assumes the pilot is maintaining the aircraft's nominal published best glide speed throughout the turn, not adjusting airspeed to some variable theoretical best glide speed. Airspeed should not be a variable.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-07-05T14:25:07.937" LastActivityDate="2019-09-01T21:19:21.333" Title="What is the optimal bank angle to accomplish a given turn in a glide?" Tags="&lt;aerodynamics&gt;&lt;emergency&gt;&lt;glider&gt;&lt;pilot-technique&gt;&lt;theory&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24243" PostTypeId="2" ParentId="24242" CreationDate="2016-01-11T01:44:23.243" Score="3" Body="&lt;p&gt;The best bank angle for a gliding aircraft to use to optimize both turn rate and sink rate can be generalized as 45°. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this is that 45° is the point at which the vertical component of lift equals the horizontal component of lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, a bank angle of 45° will produce the greatest centripetal turning force (horizontal lift) while maintaining the best sink rate (as a function of the vertical component of lift). A lesser bank angle will yield a better sink rate, but produce a lesser turn rate that decreases at a greater rate than the sink rate improves. Conversely, a greater bank angle will produce a better turn rate, but yield a greater sink rate that increases at a greater rate than the sink rate improves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This phenomenon is purely a function of bank angle, wholly independent of other design or load factors, and therefore holds true for all fixed wing aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: This may be a nominal answer, not accounting for minor variations in the L/D curves, but it satisfies my operational needs as a pilot experiencing an emergency where I will be maintaining &quot;best glide&quot; throughout a turn and my 45° bank is probably +/- 5°.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-07-04T23:53:05.427" LastActivityDate="2017-07-04T23:53:05.427" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24244" PostTypeId="2" ParentId="24242" CreationDate="2016-01-11T02:55:14.907" Score="2" Body="&lt;p&gt;Wouldn’t the mathematical problem look something like this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$V = L\cos\theta$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$H = L\sin\theta$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$R_S = k_1 (W - V)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$R_T = k_2 H$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maximize $R_T / R_S$  with respect to $\theta$ given constant $L, k_1, k_2, W$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Notation:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$\theta$ is Bank Angle&lt;/li&gt;&#xA;&lt;li&gt;$L$ is Lift&lt;/li&gt;&#xA;&lt;li&gt;$H, V$ are Horizontal &amp;amp; Vertical Components of Lift&lt;/li&gt;&#xA;&lt;li&gt;$W$ is Weight&lt;/li&gt;&#xA;&lt;li&gt;$R_S$ is Sink Rate&lt;/li&gt;&#xA;&lt;li&gt;$R_T$ is Turn Rate&lt;/li&gt;&#xA;&lt;li&gt;$k_1, k_2$ are positive constants&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Math:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R_T / R_S$ evaluates to&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{\frac{k_2 L}{k_1}\sin\theta}{W - L \sin\theta}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maximise this expression with respect to $\theta$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. When I do the math I get the $\theta$ that maximizes turn rate per sink rate as 90 degrees bank angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, I’m either messing up my math or my model. I must be wrong. Perhaps my blunder was to take lift $L$ as a constant? I suppose $L$ will change with bank too?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I guess the stall characteristics should matter? Maybe that additional constraint would say bank at max angle that won’t stall you?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. This is just back of the envelope estimation. I’m probably being naive by not considering the complexities of the issue. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="2143" LastEditDate="2016-01-11T04:15:40.773" LastActivityDate="2016-01-11T04:15:40.773" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24245" PostTypeId="1" CreationDate="2016-01-11T05:19:15.117" Score="6" ViewCount="1404" Body="&lt;p&gt;The answer &lt;a href=&quot;https://aviation.stackexchange.com/questions/2772/how-do-jet-engines-work/24213#24213&quot;&gt;here&lt;/a&gt; explains how jet engines work. During the BOOM phase air expands, however, the expansion would be in both direction, say toward the turbine blades as well as towards the compressor blades. Why is it that the compressor blades are not affected by this, because the blow could actually cause the compressor blades to rotate in the reverse direction?&lt;/p&gt;&#xA;" OwnerUserId="3703" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-11T10:23:15.993" Title="How is combustion directed in one direction in a jet engine?" Tags="&lt;jet-engine&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ClosedDate="2016-01-11T10:07:39.327" ContentLicense="CC BY-SA 3.0" />
  <row Id="24246" PostTypeId="2" ParentId="24245" CreationDate="2016-01-11T06:30:02.810" Score="5" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zAJk8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zAJk8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The shape of combustion chamber does the trick. It's expanding towards the turbine. Pressure is highest when the air leaves the last compressor disk. Fuel is added to keep pressure from dropping. The pressure it's just a bit lower but the amount and temperature of the air is much greater so the air can be used to turn turbine. To increase efficiency pressure drop is kept to minimum. If something wrong happens or throttle is advanced very fast compressor blades can be effected. The surge happens and flow direction reverses.&#xA;Look at the cutout picture of a real jet engine. It will be obvious. There are very simplified pictures of the jet engine that can make understanding confusing as they can be just wrong.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8466" LastEditDate="2016-01-11T06:42:29.777" LastActivityDate="2016-01-11T06:42:29.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24247" PostTypeId="2" ParentId="24245" CreationDate="2016-01-11T06:48:32.850" Score="2" Body="&lt;p&gt;One way to look at this is that you have a certain geometry (e.g. dia of each section, the blade spacing etc.) and a certain set of boundary conditions (e.g. far away from the system the P &amp;amp; T must return to ambient + continuum changes in P / T / flow etc. + velocity at wall set to zero) and a combustion zone with a specific mass contribution per unit time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pressure distribution and local flow profile is what evolves when you solve the governing flow and conservation equations. With the additional constraints offered by gas laws, commpressibility equations, heat transfer equations etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sure, with the right (wrong?) set of parameters you can indeed &quot;expand in both directions&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My point is, perhaps the analogy or the easy to understand qualitative explanation only takes you so far. At some point the flow direction is what evolves from solving a particular geometry with a particular set of boundary conditions. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2016-01-11T06:48:32.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24248" PostTypeId="2" ParentId="24242" CreationDate="2016-01-11T08:05:18.140" Score="6" Body="&lt;p&gt;The best bank angle is indeed 45°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be shown relatively easily that that gives the tightest turn for constant &lt;em&gt;angle of attack&lt;/em&gt;, where we assume that constant angle of attack results in constant angle of descent too. It would be pretty hard to show for constant speed, and it might not even be exactly true in that case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this &lt;em&gt;can't&lt;/em&gt; really be separated from the best speed. And the surprising answer is that the &lt;em&gt;stall&lt;/em&gt; speed (which is ~19% ($\sqrt[4]{2}$) higher than in straight flight) gives smallest loss of altitude for turning given number of degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is that the drag (near the stall speed) is proportional to $\frac{1}{v}$, but the turn radius is proportional to $v^2$, so as you slow down, the radius decreases faster then the drag (and therefore vertical speed) increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.nar-associates.com/technical-flying/impossible/possible.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.nar-associates.com/technical-flying/impossible/possible.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/786/524&quot;&gt;Is it even remotely feasible to turnback a single engine aircraft with an engine failure?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-01-11T13:26:48.773" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24249" PostTypeId="2" ParentId="24245" CreationDate="2016-01-11T08:33:35.277" Score="2" Body="&lt;p&gt;As &lt;a href=&quot;https://physics.stackexchange.com/a/208163/45810&quot;&gt;answered&lt;/a&gt; by &lt;a href=&quot;https://physics.stackexchange.com/users/71841/quadmasterxlii&quot;&gt;QuadmasterXLII&lt;/a&gt; on Physics SE:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The next question is, why do the products of the combustion go out&#xA;  through the turbine than back through the compressor? Consider: the&#xA;  compressor and turbine are approximately the same diameter, and&#xA;  turning at the same angular speed, but because the gas has expanded&#xA;  due to the combustion process, there is more volumetric flow through&#xA;  the turbine than through the compressor. Because of this, the blades&#xA;  of the turbine are angled more steeply to be at the same angle of&#xA;  attack to the local flow. This difference in angle acts as a lower&#xA;  &quot;gear ratio.&quot; -- for a given lift, the steeply angled blade generates&#xA;  less axial force and more torque. That's why, for a given pressure in&#xA;  the combustion chamber, the turbine generates more torque and controls&#xA;  which way the whole assembly turns.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As I understand it, the air duct is wider in one direction, and/or rotor blades are arranged to offer less resistance to the air exiting in that direction, so most air is exiting in that direction. This applies sufficient torque on the shaft to rotate it and overcome the reverse torque on the other end of the shaft, where the airduct is more narrow and/or the blades are additionally &quot;geared&quot; to different ratio of torque-vs-pressure-drop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These differences in air duct cross-section and blades angle of attack determine which end of the engine is which.&lt;/p&gt;&#xA;" OwnerUserId="11223" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2016-01-11T08:33:35.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24250" PostTypeId="2" ParentId="24234" CreationDate="2016-01-11T10:10:17.943" Score="3" Body="&lt;p&gt;Another problem can be pressure that can have effect on the eye. In the event of rapid decompression it's possible to lose vision. There a lot different opinions about this. Probably also depends on the particular case. If you watched movie &lt;a href=&quot;https://en.wikipedia.org/wiki/Into_Thin_Air:_Death_on_Everest&quot; rel=&quot;nofollow&quot;&gt;Into Thin Air: Death on Everest&lt;/a&gt; about &lt;a href=&quot;https://en.wikipedia.org/wiki/1996_Mount_Everest_disaster&quot; rel=&quot;nofollow&quot;&gt;1996 disaster&lt;/a&gt; one of the climbers got blind due to lasik.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="39" LastEditDate="2016-04-08T03:50:19.253" LastActivityDate="2016-04-08T03:50:19.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24251" PostTypeId="1" AcceptedAnswerId="24255" CreationDate="2016-01-11T10:14:46.053" Score="2" ViewCount="1995" Body="&lt;p&gt;Aerion together with Lockheed Martin is building the AS2 supersonic jet. This is the most realistic SS business jet project of all time. But what do they mean by SNLF technology which claims to reduce drag? And how is it better than the delta wing which they claim is inferior.&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastEditorUserId="16638" LastEditDate="2017-12-21T21:18:40.223" LastActivityDate="2017-12-21T21:18:40.223" Title="What is SNLF technology?" Tags="&lt;wing&gt;&lt;supersonic&gt;&lt;jet&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24254" PostTypeId="1" AcceptedAnswerId="24257" CreationDate="2016-01-11T11:51:28.027" Score="8" ViewCount="3416" Body="&lt;p&gt;International airports are busy places. For example, &lt;a href=&quot;http://www.heathrow.com/company/company-news-and-information/company-information/facts-and-figures&quot;&gt;London Heathrow&lt;/a&gt; saw an average of 1,290 &quot;air transport movements&quot; per day in 2014. It seems that a crash at the airport, such as &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Airways_Flight_38&quot;&gt;BA Flight 38&lt;/a&gt;, would cause major disruption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet, according to that same wikipedia page, flight operations were resumed within hours and basically back to normal within a couple of days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another more recent example is &lt;a href=&quot;https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1878&quot;&gt;Turkish Airlines Flight 1878&lt;/a&gt; crashing on landing at Istanbul. Again, the airport &quot;was temporarily closed&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are airports able to keep disruption to a minimum after (what seems to me to be) a fairly major incident, potentially involving a wrecked plane sitting on the runway? How do they move the wreckage and re-open the airport so quickly?&lt;/p&gt;&#xA;" OwnerUserId="2719" LastActivityDate="2016-01-11T16:32:29.157" Title="After a crash, for how long is the airport closed?" Tags="&lt;airport&gt;&lt;incidents&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24255" PostTypeId="2" ParentId="24251" CreationDate="2016-01-11T12:08:47.527" Score="4" Body="&lt;p&gt;SNLF stands for &lt;a href=&quot;http://www.aerionsupersonic.com/snlf/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Supersonic Natural Laminar Flow&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Laminar flow over the wing reduces the friction drag. Achieving this has been the aim of a number of designs, from the &lt;a href=&quot;http://www.allstar.fiu.edu/aero/wing31.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;laminar flow airfoils&lt;/a&gt; of the past to the latest &lt;a href=&quot;http://aviationweek.com/awin/laminar-flow-boosts-737-max-long-range-performance&quot; rel=&quot;nofollow noreferrer&quot;&gt;737 MAX winglet&lt;/a&gt;. While it is difficult enough to achieve in subsonic flight, the high wing sweep and Reynolds number in supersonic aircraft make it much more difficult to achieve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One method of achieving this is to use wings with low sweep (unlike delta wings) and sharp (supersonic leading edges) at the expense of other forms of drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8FeWq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8FeWq.png&quot; alt=&quot;SNLF&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dark colors show the expected laminar flow regions, while the graph shows the pressure gradients. Image from &lt;em&gt;Unconventional Configurations for Effecient Supersonic Flight&lt;/em&gt; by I. Kroo&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of designs have been proposed to this end from reverse delta to the Aerion's design, which looks strikingly similar to &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-104 starfighter&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One method of achieving the laminar flow (i.e. extending it chordwise) in supersonic flight is by using laminar flow control (LFC) methods like suction etc. A good example is the use of suction in a F16XL test aircraft by NASA, which produced laminar flow over nearly half of the wing (less than the design value though).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yztD3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yztD3.png&quot; alt=&quot;F16 XL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F16XL with porous titanium LFC glove on the left wing, image from NASA report TF-2004-12 DFRC, &lt;em&gt;F-16XL Supersonic Laminar Flow&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with LFC is that it increases weight and takes up space in the wing, hardly an advantage in a supersonic aircraft. So, the next thing to do is increase the laminar flow distribution without using any mechanical (or other) aids.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Natural laminar flow means the presence of laminar flow even in the absence of any LFC measures. From NASA &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwinwdL7z6HKAhXRj44KHYOuAfIQFggcMAA&amp;amp;url=https%3A%2F%2Fwww.nasa.gov%2Fpdf%2F89231main_TF-2004-12-DFRC.pdf&amp;amp;usg=AFQjCNH7ZIFA4lVsrN9y65G9GiajvPWmDg&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-16XL Supersonic Laminar Flow document&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Passive laminar flow can be achieved in the wing design process, .... Passive laminar flow can also be created on an existing wing by altering the cross-sectional contour of the lifting surface to change the pressure gradient. Both of these laminar conditions are called natural laminar flow.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;SNLF then, is basically laminar flow in supersonic flight without the aid of active boundary layer control methods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SNLF has been demonstrated in the past (unsurprisingly in F-104), but the tools to analyze it and replicate it in other aircraft were lacking. This seems to the main thrust of the Aerion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AS2's wing design has been tested by NASA in a F-15 and the results seem to be encouraging.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/INzAw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/INzAw.png&quot; alt=&quot;SLF&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SLF flight test on F-15 with NASA Dryden (top). Predicted transition (left)&#xA;and infrared image (right) showing extensive natural laminar flow. Mach 1.8, 40,000 ft., Reynolds Number about 10 million. Image from &lt;em&gt;Unconventional Configurations for Effecient Supersonic Flight&lt;/em&gt; by I. Kroo&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerion doesn't say that delta wing is inferior, but it is a simple fact that you can't use a delta wing for supersonic laminar flow. Aerion claims that its design will have 20% less drag than delta wing, but till the aircraft actually flies, we should take its announcements with a large dose of salt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other problems the company has to overcome if the product is to be successful- if the wing is thin (as I expect it to be) and quite small, the aircraft's range appears wildly optimistic. For example, the F-104 had thin wings, but had the fuselage to put the fuel in; something that is very difficult in AS2 unless the passengers agree to carry some. Also, the small wing size may lead to quite high landing speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6bRBo.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6bRBo.png&quot; alt=&quot;AS2 F104&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planform comparison of AS2 (top) and F-104. Not to scale. AS2 from company website; F-104 from Wikipedia- attributed to Kaboldy.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-11T12:08:47.527" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24256" PostTypeId="2" ParentId="24242" CreationDate="2016-01-11T12:37:32.877" Score="3" Body="&lt;h1&gt;There is no general solution, at least without further assumptions.&lt;/h1&gt;&#xA;&lt;h2&gt;What I have up to now&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The problem depends on both bank angle and airspeed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;We can calculate the angular velocity (turn rate) from bank angle and airspeed&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\omega = \frac{g \cdot tan~\theta}{v_H}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;We can look up the vertical velocity from the (bank angle corrected) polar curve&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$v_V = \frac{f(v_H \cdot \sqrt{cos~\theta~~})}{\sqrt{cos~\theta~~}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;We can calculate the ratio &lt;span class=&quot;math-container&quot;&gt;$\frac{\omega}{v_V}$&lt;/span&gt; that the asker wants to maximize for any airspeed and bank angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Without any knowledge of the polar in analytical form or assumptions we're stuck here.&lt;/p&gt;&#xA;&lt;h2&gt;Proof&lt;/h2&gt;&#xA;&lt;p&gt;Let &lt;span class=&quot;math-container&quot;&gt;$\theta$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$a_N$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$a_H$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$a_V$&lt;/span&gt; be bank angle, normal, horizontal and vertical acceleration. Their relationships are:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$a_V = a_N \cdot cos~\theta$$&lt;/span&gt; &lt;span class=&quot;math-container&quot;&gt;$$a_H = a_N \cdot sin~\theta$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;with &lt;span class=&quot;math-container&quot;&gt;$a_V = 1g$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$a_N = \frac{1}{cos~\theta} \cdot 1g$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$a_H = a_N \cdot sin~\theta = \frac{sin~\theta}{cos~\theta} \cdot 1g = g \cdot tan~\theta$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Let &lt;span class=&quot;math-container&quot;&gt;$r$&lt;/span&gt; and &lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; be turn radius and angular velocity. Let &lt;span class=&quot;math-container&quot;&gt;$v_H$&lt;/span&gt; be the airspeed. The horizontal acceleration is the centripetal acceleration in our turn, so:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\frac{v_H^2}{r} = g \cdot tan~\theta$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;The angular velocity (turn rate) is:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$\omega = \frac{v_H}{r} = \frac{g \cdot tan~\theta}{v_H}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;Let &lt;span class=&quot;math-container&quot;&gt;$v_V$&lt;/span&gt; be the sink rate which is a function &lt;span class=&quot;math-container&quot;&gt;$f$&lt;/span&gt; of the airspeed. The function &lt;span class=&quot;math-container&quot;&gt;$f$&lt;/span&gt; is usually given as &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_curve_%28aerodynamics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;polar curve&lt;/a&gt;. For load factors other than &lt;span class=&quot;math-container&quot;&gt;$1g$&lt;/span&gt;, we have to scale it by the square root of the load factor &lt;span class=&quot;math-container&quot;&gt;$k$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$k = \frac{1}{\sqrt{cos~\theta~~}}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$v_V = k \cdot f \left( \frac{v_H}{k} \right)$$&lt;/span&gt;&lt;/p&gt;&#xA;" OwnerUserId="12930" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-11T12:37:32.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24257" PostTypeId="2" ParentId="24254" CreationDate="2016-01-11T13:06:59.113" Score="15" Body="&lt;p&gt;It completely depends on the accident and airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example if I crash land on 10R at San Francisco, and it's a fairly quiet time of day (eg below the capacity of one runway), the airport could just use 10L and continue operations as normal. Similarly if there was no wind they could just switch to 1/19 L/R instead of 10/28 L/R. I'll discuss this toward the end of this answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the crash didn't damage the runway, if the accident didn't damage the runway and the aircraft could be safely moved the airport would be back to normal as soon as the aircraft was moved and the runway had been checked. This could be within an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand if at a single runway airport, with severe damage to the runway and a need to leave the aircraft in situ to be inspected, it could take several weeks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the cases you mentioned, BA 38 landed short of the runway. The airport was closed to arrivals for a few hours, however, and hundreds of flights were delayed, cancelled, or diverted. In the meantime, the runway in question (27L) was closed entirely for arrivals until 3 days later when the aircraft was recovered. However the runway re-opened on the day of the accident for departures only. As Heathrow typically operates with one runway for Departures and one for Arrivals, this had minimal impact on operations: &lt;a href=&quot;http://theaviationist.com/2008/01/20/ba038-b772-crash-landing-at-heathrow/&quot;&gt;ref&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Turkish flight 1878, the aircraft impacted Runway 5, then again on Runway 35L, but as far as I'm aware no significant damage was done. The other runways were inspected and used until the aircraft was moved. Ataturk is a busy airport, but not so busy that it can't cope with the loss of a single runway. Again a few hundred flights were delayed, cancelled, or diverted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In neither incident was wreckage left on the actual runway, so once inspected they could be used as normal. There was some disruption in both cases - although no more than that caused by bad weather. If the aircraft had remained on the runway in either case, however, and had the accidents been at a single airport runway (eg London Stansted rather than Heathrow), the airport would likely have been closed for several days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another interesting case is &lt;a href=&quot;https://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot;&gt;Asiana Airlines flight 214&lt;/a&gt; - an accident at San Francisco which closed the Airport for a few hours, and the runway for around a day. The other two runways (1/19 L/R which are perpendicular, as San Francisco has 4 runways arranged as 2 pairs) re-opened after around an hour and meant there was minimal impact, along with the parallel runway (10L/28R) which re-opened 24 hours later. The accident runway (10R/27L) re-opened around a week later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to note is that in most cases, an airport only needs runways in one direction - so for example at San Francisco there is a lot of resilience in the runways. As long as the accident doesn't cause damage too close to the &quot;crossover&quot; of the runways, San Francisco should almost always be able to operate at near full capacity shortly after an accident, even with a runway closed, due to always having a pair of runways available. Airports such as Heathrow with a single pair of runways are less resilient&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2016-01-11T16:32:29.157" LastActivityDate="2016-01-11T16:32:29.157" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24258" PostTypeId="2" ParentId="24254" CreationDate="2016-01-11T13:07:27.840" Score="6" Body="&lt;p&gt;Your last line has something of a false premise - once the initial rescue is over (and presuming that there's no implication that airport operations caused the accident), there'd generally be no reason not to re-open using alternative runways. Flight 38 wasn't moved for several days - it just wasn't blocking all of the runways! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers might not enjoy the site of a stricken jet, but it's not a particular issue that they see it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most jurisdictions, the rescue and investigation authorities 'own' the scene immediately after an accident and it's essentially up to them. They'll generally take a proportional view depending on the circumstances - there's little to be gained closing an entire airport because an aircraft suffered a mechanical failure with few injuries. It won't help the investigation, it's not going to destroy forensic evidence, it isn't putting anybody in further danger and will only serve to annoy the public and lose money for the operators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand - if controllers at London Heathrow had someone caused an aircraft collision resulting in fatalities then I expect the airport would remain closed for a lengthy period of time as investigators work to forensically analyse the scene.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not quite comparable, but after the Shoreham jet crash the road remained completely closed for a week, and only fully reopened after several.&lt;/p&gt;&#xA;" OwnerUserId="2160" LastActivityDate="2016-01-11T13:07:27.840" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24259" PostTypeId="1" AcceptedAnswerId="24273" CreationDate="2016-01-11T14:16:42.177" Score="12" ViewCount="1418" Body="&lt;p&gt;I work on time-space cartography in a historical perspective and need to establish a commercial speed of Concorde aircraft flights based on timetable data. This issue differs from &lt;a href=&quot;https://aviation.stackexchange.com/questions/11936/are-we-at-peak-speed-efficiency-for-jet-airliners-at-mach-0-85&quot;&gt;the issue of the maximum speed of planes&lt;/a&gt;, because in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Time_geography&quot; rel=&quot;noreferrer&quot;&gt;time geography&lt;/a&gt; perspective I want to consider speed from the point of view of the user, the traveller, i.e timetable commercial speed, and not maximum aircraft speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found some indicative timetables of London-New York in 3,5 hours for 5 850 km which turns into an approximate value of 1 600 km/h. Could anyone confirm these data and this figure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A related problem is that time-tables are not symmetric, because of &lt;a href=&quot;https://en.wikipedia.org/wiki/Trade_winds&quot; rel=&quot;noreferrer&quot;&gt;trade winds&lt;/a&gt;, so that transatlantic routes take longer from Europe to USA that the contrary. I want to use the longest value since it provides a consistent value for minimum time-distance.&lt;/p&gt;&#xA;" OwnerUserId="12955" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-09-05T18:22:33.163" Title="What was the commercial speed of Concorde?" Tags="&lt;commercial-operations&gt;&lt;concorde&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24260" PostTypeId="2" ParentId="24259" CreationDate="2016-01-11T14:23:41.397" Score="3" Body="&lt;p&gt;Well, this is very dependent on the windspeeds for a local area which changes day by day. The official &quot;Cruise speed&quot; for Concorde is 2140 kph. Other than that, your question is way too broad because the &quot;relative airspeed&quot; varies by day and time of day as well as location.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-11T14:23:41.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24261" PostTypeId="2" ParentId="24259" CreationDate="2016-01-11T14:23:56.153" Score="11" Body="&lt;p&gt;The &lt;a href=&quot;http://www.britishairways.com/en-us/information/about-ba/history-and-heritage/celebrating-concorde&quot;&gt;Concorde cruised at 1350mph&lt;/a&gt; (~Mach 2.05 at 55,000Ft.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde’s fastest transatlantic crossing was on 7 February 1996 when it completed the New York to London flight in &lt;a href=&quot;http://www.britishairways.com/en-us/information/about-ba/history-and-heritage/celebrating-concorde&quot;&gt;2 hours 52 minutes and 59 seconds&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it flew the &lt;a href=&quot;http://www.concordesst.com/faq.html&quot;&gt;average flight time (was) around 3 hours 30 minutes&lt;/a&gt;, but can be slightly longer if the aircraft (needed) to hold before landing at the local airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind is a huge factor in flying. A headwind or tail wind can mean a big difference in flight time. The Concorde cruised at a &lt;a href=&quot;http://www.popsci.com/article/technology/what-it-was-fly-concorde-supersonic-airplane&quot;&gt;significantly higher altitude than most airplanes ~55,000Ft&lt;/a&gt;. which means it was subject to very different wind than its sub sonic lower flying counterparts. At that altitude winds in excess of 100Kt are common place. So you could see a 200Kt difference in speed depending on direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also of note the speed was often called out using &lt;a href=&quot;https://en.wikipedia.org/wiki/Mach_number&quot;&gt;Mach's Number&lt;/a&gt; (the Concorde flew a bit over Mach 2). However since Mach's number accounts for air density, &lt;a href=&quot;http://www.fighter-planes.com/jetmach1.htm&quot;&gt; Mach 1 at 55,000Ft. is 660MPH&lt;/a&gt; which is significantly lower than the &lt;a href=&quot;http://www.fighter-planes.com/jetmach1.htm&quot;&gt;often quoted Mach 1 = 760MPH&lt;/a&gt; (which is the speed of sound at sea level).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the best sources of info on flying the Concorde is &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot;&gt;this podcast interviewing one of the pilots&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-11T23:56:56.913" LastActivityDate="2016-01-11T23:56:56.913" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24262" PostTypeId="2" ParentId="24259" CreationDate="2016-01-11T16:29:25.503" Score="2" Body="&lt;p&gt;When I flew on it in 2000, the Mach meter at the front of the passenger cabin varied from 1.99 to 2.01&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-11T20:34:17.317" LastActivityDate="2016-01-11T20:34:17.317" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24263" PostTypeId="2" ParentId="23688" CreationDate="2016-01-11T16:31:41.353" Score="7" Body="&lt;p&gt;&lt;em&gt;EDIT: Note that the original question, which this answer primarily addresses, did not specify electrical connectors.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;The FAA does provide regulations which at least partially cover this subject, though the guidance is rather broad.&lt;/p&gt;&#xA;&lt;p&gt;The airworthiness standards in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=42b51ed9d4cdc3d3ea63506e64bfbec4&amp;amp;mc=true&amp;amp;node=se14.1.23_1607&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;14 CFR 23.607&quot;&gt;14 CFR 23.607&lt;/a&gt; for normal, utility, acrobatic, and commuter category airplanes stipulate that:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Each removable fastener must incorporate two retaining devices if the loss of such fastener would preclude continued safe flight and landing.&lt;/p&gt;&#xA;&lt;p&gt;(b) Fasteners and their locking devices must not be adversely affected by the environmental conditions associated with the particular installation.&lt;/p&gt;&#xA;&lt;p&gt;(c) No self-locking nut may be used on any bolt subject to rotation in operation unless a non-friction locking device is used in addition to the self-locking device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Likewise, the  airworthiness standards in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=42b51ed9d4cdc3d3ea63506e64bfbec4&amp;amp;mc=true&amp;amp;node=se14.1.25_1607&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;14 CFR 25.607&quot;&gt;14 CFR 25.607&lt;/a&gt; for transport category airplanes stipulate that:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Each removable bolt, screw, nut, pin, or other removable fastener must incorporate two separate locking devices if—&lt;/p&gt;&#xA;&lt;p&gt;(1) Its loss could preclude continued flight and landing within the design limitations of the airplane using normal pilot skill and strength; or&lt;/p&gt;&#xA;&lt;p&gt;(2) Its loss could result in reduction in pitch, yaw, or roll control capability or response below that required by Subpart B of this chapter.&lt;/p&gt;&#xA;&lt;p&gt;(b) The fasteners specified in paragraph (a) of this section and their locking devices may not be adversely affected by the environmental conditions associated with the particular installation.&lt;/p&gt;&#xA;&lt;p&gt;(c) No self-locking nut may be used on any bolt subject to rotation in operation unless a nonfriction locking device is used in addition to the self-locking device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As you can see, these regulations do prohibit certain types of locking fasteners in certain circumstances. For example, a nylon self-locking nut is not acceptable to fasten the exhaust manifold to the cylinder head; an all-metal self-locking nut would be acceptable, however.&lt;/p&gt;&#xA;&lt;p&gt;The greater concern for a system such as a headset may be that to install it with fastening hardware—screws for example—would be to make it an installed part of the aircraft. The installation would then be subject to the various regulations of an installation: a log book entry, weight and balance considerations, etc.&lt;/p&gt;&#xA;&lt;p&gt;Additionally, &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2007.pdf&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;AC 43-13-1B, Ch 7&quot;&gt;AC 43-13-1B, Ch 7&lt;/a&gt;, provides non-regulatory guidance regarding use of fasteners, including the use of locking and safety mechanisms. I will note that this guidance is superseded by manufacturer maintenance data for most modern aircraft.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-12T14:03:14.783" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24264" PostTypeId="2" ParentId="24133" CreationDate="2016-01-11T16:33:59.930" Score="7" Body="&lt;p&gt;Your understanding is partly right. Usually HSI indicators are associated with a slaving transmitter that includes the flux gate (the magnetic sensor), but also other elements such the directional gyro unit and a slaving control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a typical system will usually include the below components (there are different designs, so check the characteristics of the equipment in your aircraft):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Horizontal Situation Indicator (HSI) is the panel mounted cockpit indicator that provides a comprehensive display including usually at least heading, course, and glide scope. The heading indicator of the HSI is a remote indicating compass that gets its information from a remote slaving transmitter.&lt;/li&gt;&#xA;&lt;li&gt;The magnetic slaving transmitter includes the flux gate that is the magnetic sensor itself, and some electronics to send the heading information to the directional gyro and HSI. This transmitter and its associated flux gate is usually located in a wingtip to minimize as much as possible magnetic interference.&lt;/li&gt;&#xA;&lt;li&gt;a directional gyro unit that is usually remote mounted. It is using its internal gyroscope to keep and provide a stable heading reference during turns. This gyro unit is driven/slaved to the slaving transmitter.&lt;/li&gt;&#xA;&lt;li&gt;The slaving control is panel mounted and allows to selected either &quot;slaved gyro&quot; or &quot;free gyro&quot; mode. Usually, the system is in &quot;slaved gyro&quot; mode and will be slaved automatically. In &quot;free gyro&quot; mode, a slaving meter indicator displays the difference between indicator display and earth's magnetic field, and it is possible to align manually the switch using clockwise or counterclockwise buttons.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://bendixking.com/en/~/media/bendixking/files/006-08256-0004_4-kcs-55-55a-ki-525a-pilot-s-guide.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;manual of the Bendix-King KCS 55A&lt;/a&gt; provides a good introduction to HSI design and operation.&lt;/p&gt;&#xA;" OwnerUserId="12957" LastEditorUserId="12049" LastEditDate="2018-07-01T14:57:11.527" LastActivityDate="2018-07-01T14:57:11.527" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24265" PostTypeId="2" ParentId="8580" CreationDate="2016-01-11T17:48:57.143" Score="1" Body="&lt;p&gt;I was taught similarly.  √ftALT×1.26 = Distance in NM. So 1981 m = 6500 ft, 335 m=1100ft, then difference =5400 ft. √5400*1.26=73.4*1.26=92.5 nm. &lt;/p&gt;&#xA;" OwnerUserId="12959" LastActivityDate="2016-01-11T17:48:57.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24267" PostTypeId="1" AcceptedAnswerId="24338" CreationDate="2016-01-11T19:17:57.037" Score="1" ViewCount="834" Body="&lt;p&gt;Where can I find Radar Weather Reports (&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2012.pdf&quot; rel=&quot;nofollow&quot;&gt;RAREPs&lt;/a&gt;)? Are they still used? They are not anywhere on the &lt;a href=&quot;http://www.aviationweather.gov/&quot; rel=&quot;nofollow&quot;&gt;aviationweather.gov&lt;/a&gt; website.&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-01-11T21:25:34.980" LastActivityDate="2016-01-14T10:44:59.633" Title="Where does one obtain a RAREP?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24268" PostTypeId="1" AcceptedAnswerId="24270" CreationDate="2016-01-11T23:10:40.973" Score="1" ViewCount="294" Body="&lt;p&gt;I plan to operate in the Caribbean (Antigua, under ECCAA jurisdiction, which does not have a glider rating of its own) and not in the USA or Canada. I am looking at which one would be require less work and time on my side. I plan to give rides in my country and practice the sport.&lt;/p&gt;&#xA;" OwnerUserId="12967" LastEditorUserId="3825" LastEditDate="2016-01-12T04:02:29.900" LastActivityDate="2016-01-12T04:02:29.900" Title="Which should I get a FAA glider licence or a Canadian glider licence?" Tags="&lt;faa&gt;&lt;glider&gt;&lt;transport-canada&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24270" PostTypeId="2" ParentId="24268" CreationDate="2016-01-12T00:17:26.490" Score="2" Body="&lt;p&gt;This is heavily dependent on the local jurisdictions you plan to operate in and what their laws are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off you must find out if your desired countries of operation accept foreign certificates. This varies heavily all over the world and can range from full no questions asked acceptance, to you needing to simply take the test again (in that country) through any various case you can think of. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second you need to find out what certificate you need. Here in the US to give rides (and receive compensation for such) you need a commercial certificate. This looks like it &lt;a href=&quot;http://www.ssa.org/GliderPilotRatings&quot; rel=&quot;nofollow&quot;&gt;extends to gliders as well&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hours. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requires a few more hours than the Canadian certificate will, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ssa.org/GliderPilotRatings&quot; rel=&quot;nofollow&quot;&gt;FAA&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Are at least 16 years of age; and &lt;/li&gt;&#xA;  &lt;li&gt;Have logged at least 10 hours of&#xA;  flight time in a glider and that flight time must include at least 20&#xA;  total glider flights, and &lt;/li&gt;&#xA;  &lt;li&gt;Have 2 hours of solo flight time in a&#xA;  glider, and &lt;/li&gt;&#xA;  &lt;li&gt;Have passed the FAA written examination; and &lt;/li&gt;&#xA;  &lt;li&gt;Have passed the flight exam with a FAA Examiner.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sac.ca/website/index.php/fr/home-all/learning-to-soar&quot; rel=&quot;nofollow&quot;&gt;Canada&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;A minimum of 6 hours of flight training under the direction and supervision of an instructor&lt;/li&gt;&#xA;  &lt;li&gt;At least 2 hours of solo flight time, including a minimum of 20 takeoffs and 20 landings&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Right off the bad Canada requires 4 less hours which, no matter how you spin it will be cheaper (since you have to pay for less time). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the US if you are not a citizen you will need to pass an NTSB background check to train. I do not know if Canada has a similar requirement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Travel, assuming you are in the Caribbean already it may be cheaper to travel to Florida (or the like) to train then go all the way up to Canada for your training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this document the ECCAA does issue glider ratings &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.eccaa.aero/images/stories/docs/cars/Part%2002%20-%20Personnel%20Licensing%20A&amp;amp;B%20.pdf&quot; rel=&quot;nofollow&quot;&gt;2.1.2.3 RATINGS ISSUED&lt;/a&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The Authority may issue the following ratings for pilots&lt;br&gt;&#xA;  (i) Category ratings in the following aircraft:&lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;(a) Aeroplane;&lt;/li&gt;&#xA;  &lt;li&gt;(b) Rotorcraft; &lt;/li&gt;&#xA;  &lt;li&gt;(c) Glider; &lt;/li&gt;&#xA;  &lt;li&gt;(d) Lighter-than-air; &lt;/li&gt;&#xA;  &lt;li&gt;(e) Power lift.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-12T00:24:23.053" LastActivityDate="2016-01-12T00:24:23.053" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24272" PostTypeId="1" AcceptedAnswerId="24274" CreationDate="2016-01-12T08:51:18.163" Score="6" ViewCount="907" Body="&lt;p&gt;How close can separation between two aircraft be during landing? &lt;s&gt;during visual landing clearance? &lt;/s&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, I refer to this Aviation Herald Report where:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When the Boeing 777-300 was about 2.1nm before touch down a BAe Avro&#xA;  began its takeoff run on runway 08R. The Boeing 777 was subsequently&#xA;  cleared to land on runway 08R, winds from 130 degrees at 7 knots. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;When the Boeing 777-300 crossed the runway threshold, the Jumbolino&#xA;  was climbing out still short of the runway end.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://avherald.com/h?article=445873f3&quot; rel=&quot;nofollow noreferrer&quot;&gt;www.avherald.com&lt;/a&gt; - Singapore B773 at Munich on Nov 3rd 2011, runway excursion)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it typical for two aircraft to be so close during landing? i.e. Essentially both landing &amp;amp; departing aircraft are simultaneously overflying the same runway but at opposite ends. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much closer would cause the landing aircraft to abort? Would one proceed with landing even if when one crossed the threshold the other craft was just rotating?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's other things that went wrong in that incident,  but I'm only asking about the close separation in the landing clearance &lt;s&gt;visual clearance &lt;/s&gt;aspect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. I've edited the question to remove a confusing misunderstanding. It was apparently not a visual clearance. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2017-03-17T08:53:29.660" LastActivityDate="2017-03-17T08:53:29.660" Title="How close can separation be during a landing clearance?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;takeoff&gt;&lt;lba-regulations&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24273" PostTypeId="2" ParentId="24259" CreationDate="2016-01-12T09:36:15.063" Score="3" Body="&lt;p&gt;I want to measure a commercial speed for Concorde flights. The answer was given by Andy in his comments providing links to websites that recorded past timetables for Concorde: &lt;a href=&quot;http://forums.flightsimlabs.com/index.php?/topic/4874-complete-list-of-concorde-scheduled-flights/&quot; rel=&quot;nofollow&quot;&gt;forums.flightsimlabs.com&lt;/a&gt; and  &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/3820978/&quot; rel=&quot;nofollow&quot;&gt;www.airliners.net&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Timetable schedule must take into account time difference between cities so that a British Airways Concorde flight JFK 12h15 to LHR 21h00 with -5 hours difference will give a 3h45 of commercial flight duration. Surprisingly, to me at least, trade winds did not seem to play a significant role in this measurement because timetable on the reverse route exhibit similar duration. Air France flights follow the same rationale. The measurement indicate a general figure of &lt;strong&gt;3h45&lt;/strong&gt; for transatlantic Concorde flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next step is determining the kilometre distance. As I want a geographical time-distance I care only about &lt;a href=&quot;https://en.wikipedia.org/wiki/Great-circle_distance&quot; rel=&quot;nofollow&quot;&gt;great circle distance&lt;/a&gt; and do not care about the exact path followed by the flight which would tell about aircraft/pilot/airline performance. I used the  &lt;a href=&quot;http://fr.flightaware.com&quot; rel=&quot;nofollow&quot;&gt;flightaware.com&lt;/a&gt; website. My only issue is measuring the performance (speed) of the transport system in getting from point A to point B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I finally have my figure: 5 850 km / 3h45 = &lt;strong&gt;1 560 km/h was the commercial speed of Concorde&lt;/strong&gt; (or 969 mph in non international units).&lt;/p&gt;&#xA;" OwnerUserId="12955" LastEditorUserId="12955" LastEditDate="2016-01-14T10:49:25.943" LastActivityDate="2016-01-14T10:49:25.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24274" PostTypeId="2" ParentId="24272" CreationDate="2016-01-12T11:03:15.810" Score="9" Body="&lt;p&gt;According to the &lt;a href=&quot;http://avherald.com/h?article=445873f3&quot; rel=&quot;nofollow noreferrer&quot;&gt;avherald article&lt;/a&gt;, the airport was operating below visual minima, thus no visual approach would have been possible. Unfortuntely, the ATC communication transcript is not available, so we will will not know whether the CAT III AutoLand approach by the B773 was communicated to ATC, which would not allow the Avro to enter the runway protected area during the B773's approach or whether this was a decision by the B773 crew only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the airport was operating under CAT I procedures, the B773 is likely to have been cleared for a CAT I ILS approach. The Avro will have been cleared for departure before the B773 was cleared to land, ATC has most likely used a &lt;a href=&quot;https://aviation.stackexchange.com/a/7661/572&quot;&gt;non-withheld landing clearance&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;321.5 Landing clearance need not be withheld until prescribed separation exists if there is reasonable assurance that the appropriate separation will exist when the aircraft crosses the runway threshold. However, do not clear an aircraft to land before a preceding landing aircraft has crossed the runway threshold.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The runway is considered no longer occupied if the preceding departing aircraft has reached V&lt;sub&gt;r&lt;/sub&gt; and has rotated, although still being over the runway. If ATC can be reasonably sure that this will be the case when the landing aircraft crosses the threshold, the landing clearance can be issued.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The BFU bulletin reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The B777 crossed the runway threshold of 08R at 12:09:09 in 40ft. Six seconds later, the BAe Avro crossed the opposite runway threshold at approx. 380ft.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.bfu-web.de/DE/Publikationen/Bulletins/Functions/bulletins2011_table.html?nn=223244&quot; rel=&quot;nofollow noreferrer&quot;&gt;BFU Bulletin NOV 2011&lt;/a&gt; - Translation: Own Work)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it typical for aircraft to be so close during approach and departure? Yes, aircraft can be close during these phases, depending on procedures in use and meteorological conditions. Aircraft can be asked to maintain visual separation to preceding traffic in VMC, however without the full transcript of the ATC communication, this will not be answerable in regards to your scenario in Munich.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-10-24T16:53:22.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24275" PostTypeId="1" CreationDate="2016-01-12T11:12:12.173" Score="9" ViewCount="4620" Body="&lt;p&gt;In the question &lt;a href=&quot;https://aviation.stackexchange.com/questions/13174/whats-the-preferred-approach-for-a-passenger-jet/24232?noredirect=1#comment56486_24232&quot;&gt;What&amp;#39;s the preferred approach for a passenger jet?&lt;/a&gt; it is mentioned that pilots prefer Visual Approaches over ILS Approaches, as they are a lot quicker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would a visual approach be quicker than an ILS approach?&lt;/p&gt;&#xA;" OwnerUserId="1720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-12T17:07:05.110" Title="What makes a visual approach quicker than an ILS approach?" Tags="&lt;ils&gt;&lt;visual-approaches&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24276" PostTypeId="2" ParentId="24275" CreationDate="2016-01-12T11:24:15.650" Score="13" Body="&lt;p&gt;Visual approaches can be conducted from any point around the airport where the runway is in sight, e.g. if you are approaching from the north of the airport, you can be vectored to a position which is closer to the airport and be cleared for a visual approach from a position where you can turn visually and reach the runway threshold.&lt;/p&gt;&#xA;&lt;p&gt;ILS approaches begin at the approach gate before the final approach fix (FAF) for the localizer and glidepath indications to be correctly used and the aircraft configured for the approach. The FAF is at many airport around 10 NM from the runway threshold at 3.000ft AGL, thus placing the approach gate at around 12-14 NM.&lt;/p&gt;&#xA;&lt;p&gt;A pilot on a forum has summed it up like this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Visual approaches are usually shorter than instrument approaches. By that, I mean that the turn to final is accomplished closer to the runway when on a visual approach.&lt;/p&gt;&#xA;&lt;p&gt;When traffic is heavier, or weather is around, or it's hazy, smoggy, etc, ATC will usually route everyone out for an ILS.&lt;/p&gt;&#xA;&lt;p&gt;Many times, a pilot will call runway in sight, yet be sequenced behind someone who is on the ILS. So, he'll get routed out for an ILS approach, even though he'll go visual within the cockpit.&lt;/p&gt;&#xA;&lt;p&gt;Airport size doesn't have a whole lot to do with it. Also, even though an aircraft may be on a visual approach, that does not absolve ATC of separation resposibility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/439124&quot; rel=&quot;noreferrer&quot;&gt;www.airliners.net&lt;/a&gt; - Author: Tom in NO)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Effectively, this means that visual approaches tend to be shorter and quicker than ILS approaches with vectors to the FAF/approach gate.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-12T17:07:05.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24277" PostTypeId="1" CreationDate="2016-01-12T11:49:36.280" Score="8" ViewCount="1832" Body="&lt;p&gt;I was wondering if this might make sense as commercial aircraft design has not changed significantly (from the outside) in the last 50 years?&lt;/p&gt;&#xA;" OwnerUserId="12637" LastActivityDate="2019-06-18T20:15:23.377" Title="Can old passenger airplanes be refitted with latest engines to extend their life and efficiency?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24278" PostTypeId="1" CreationDate="2016-01-12T11:57:42.740" Score="3" ViewCount="567" Body="&lt;p&gt;This might make sense as&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;commercial aircraft basic design has remained the same for the last 50 years or so, but materials used have changed&lt;/li&gt;&#xA;&lt;li&gt;parts such as wings, landing gear, nose, tail, jet engine, fuselage, avionics and seats all come from different specialized manufacturers&lt;/li&gt;&#xA;&lt;li&gt;so OEMs like Boeing, Airbus, etc., can build modular planes where each of the above mentioned parts should be replaceable with a better upgraded part&lt;/li&gt;&#xA;&lt;li&gt;and this can prevent wastage&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12637" LastEditorUserId="7532" LastEditDate="2017-09-05T19:44:37.177" LastActivityDate="2017-09-06T18:22:02.087" Title="What are the issues with building modular aircraft?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24279" PostTypeId="2" ParentId="24278" CreationDate="2016-01-12T12:17:25.660" Score="1" Body="&lt;p&gt;The centre of gravity of an assembled and loaded plane must be in the right position, relative to the position where the wings are connected.  Fitting a different tail, nosegear, engines would affect the fore and aft position of the cg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore we would need a fuselage where the wing position could be varied according to the chosen configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Problem: the fuselage needs to be as light as possible in most places, &lt;strong&gt;and&lt;/strong&gt; strengthened in the place where the wings are connected.  So we would end up needing a different fuselage for every configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(There are many other reasons why a totally flexible modular approach is impractical, but I've given the most basic engineering-based one I can think of.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2016-01-12T12:17:25.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24280" PostTypeId="1" CreationDate="2016-01-12T13:06:55.543" Score="17" ViewCount="2384" Body="&lt;p&gt;I work as ATC in Korea. I have question about the exact meaning of the word 'intercept'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In FAA order 7110.65, 5-9-1 vector to final approach course, &quot;vector to intercept the final approach course&quot;, The Korean manual interprets the word of the sentence 'intercept' as &quot;crossing&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the word 'intercept' means not 'crossing' but means the state just on the final, not exactly crossing but  just 'established'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason why i have question about this is that in the PAR approach, for precision approach, the final controller can vector aircraft to be exactly on the final beyond the faf although he started control in the state aircraft is not exactly on final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I think 'intercept' doesn't mean &quot;crossing&quot; but something else... Because I'm not a native English speaker I want to know the exact meaning of the word 'intercept'.&lt;/p&gt;&#xA;" OwnerUserId="12972" LastEditorUserId="16638" LastEditDate="2020-03-14T21:18:39.573" LastActivityDate="2020-03-14T21:18:39.573" Title="What does 'intercept final' exactly mean?" Tags="&lt;air-traffic-control&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="24281" PostTypeId="2" ParentId="24280" CreationDate="2016-01-12T13:47:29.620" Score="13" Body="&lt;p&gt;You are correct. The verb &lt;em&gt;intercept&lt;/em&gt;, as used by ATC and pilots means to track to and then turn onto a given course. In your given example, &lt;em&gt;&quot;vector to intercept the final approach course&quot;&lt;/em&gt;, a vector to intercept is a vector which will cross the final approach course and from which the pilot will be able to commence a turn to become established on the final approach course. To intercept the final approach course means to accomplish that turn onto the final approach course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this additional example from an excerpt from Section 4 of the &lt;a href=&quot;https://www.gleim.com/aviation/faraim/?leafNum=8523f5b7&amp;amp;terms[]=intercept#avTab%3DleafNum%3D8523f5b7&quot;&gt;Aeronautical Information Manual (AIM)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;5-4-3. b. 1.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The pilot is not expected to turn inbound on the final approach&#xA;  course unless an approach clearance has been issued. This clearance&#xA;  will normally be issued with the final vector for &lt;strong&gt;interception&lt;/strong&gt; of&#xA;  the final approach course, and the vector will be such as to enable&#xA;  the pilot to establish the aircraft on the final approach course prior&#xA;  to reaching the final approach fix.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-12T13:55:08.763" LastActivityDate="2016-01-12T13:55:08.763" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24282" PostTypeId="2" ParentId="24277" CreationDate="2016-01-12T15:41:44.280" Score="0" Body="&lt;p&gt;While the design of aircraft may not look different to previous generations of aircraft, the technology behind them is vastly different, from lightweight carbon fibres, to far more aerodynamic wings. New design aircraft provide vastly better operating economics than aircraft based off an old design but with newer engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take for example the A350, which Airbus claim delivers a 25% fuel reduction per seat when compared to existing aluminium long-haul aircraft. The A330neo on the other hand, which is a re-engined version of the A330 (but also containing revised wingtips and some other minor aerodynamic enhancements), is only expected to deliver a 14% fuel burn advantage per seat over the current A330.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this is with a newly built A330neo rather than taking an old A330 and putting new engines on an existing frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many reasons why putting new engines on older airframes are not a good idea. First off, simply swapping out the engines is not feasible - the chances are the new engines will have different mounting points, and different fuel flow requirements, requiring a complete redesign of the fuel flow system. You would also need to revise the avionics, to take into account revised engine operating parameters. Operating procedures for pilots would also be different between models, leading to either the need for separate pools of pilots per engine type, or if pilots are crossing between models, an increased risk of pilot error leading to an accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the biggest reason why this is not done, is that aircraft fuselages have a limited lifespan. With every flight, you are pressurising the aircraft, then de-pressurising it for landing. This causes metal fatigue to the frame. This alone is the single biggest cause of aircraft being retired. It is required that aircraft undergo a &quot;D-Check&quot; roughly every 6 years. This involves stripping the entire aircraft, and removing all paint from the outside, so the state of the fuselage can be checked for signs of metal fatigue. This is a hugely expensive and time consuming process, and as a result most aircraft only every go through a few of these before they are retired.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So re-fitting an aircraft with newer engines would not be feasible as the air frame would have exceeded its lifespan anyway and would need replacing, so far better to just buy a new build aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1720" LastEditorUserId="38099" LastEditDate="2019-06-18T20:15:23.377" LastActivityDate="2019-06-18T20:15:23.377" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="24283" PostTypeId="2" ParentId="24277" CreationDate="2016-01-12T15:44:51.050" Score="6" Body="&lt;p&gt;Yes, this can and does happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two examples that I think are excellent illustrations of the concept are turbine conversions of the Beech 18 and the Douglas DC-3. In these cases the old radial piston engines were replaced with turbo-prop engines. Other examples also exist, including less drastic modifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a Beech 18 modification is the Volpar Turbo Beech conversion which used Garrett TPE-331 engines. Information on that conversion &lt;a href=&quot;http://everything.explained.today/Beechcraft_Model_18/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;, and an example of the operational use of such modified aircraft &lt;a href=&quot;http://john2031.com/twin_beech_18/k&amp;amp;k_aircraft_turbine/photos_and_information.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a DC-3 conversion is the Basler BT-67, which uses PT6A-67 series engines. Information on that conversion &lt;a href=&quot;https://en.wikipedia.org/wiki/Basler_BT-67&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.baslerturbo.com/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-12T17:43:48.883" LastActivityDate="2016-01-12T17:43:48.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24284" PostTypeId="2" ParentId="24275" CreationDate="2016-01-12T15:58:09.740" Score="6" Body="&lt;p&gt;Visual approaches are preferred because it means you can potentially avoid being vectored out to intercept the final approach fix (FAF) which needs to be done for a an ILS approach.  If there is a long line of aircraft being vectored for the approach this may not yield any time savings as minimum spacing with the aircraft in front of you becomes a factor.  At an airport that isn't busy this can be the difference between flying a tight traffic pattern and landing quickly or a long vector 5+ miles past the airport to join the approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, being on a visual approach clearance with the aircraft in front of you in sight relieves the controller from providing normal spacing.  This means you can squeeze a bit closer to the airplane you are following and you just have to make sure you are keeping far enough back that the runway will be clear when you get to it.  This can also help if the airplane in front of you slows down unexpectedly or too early, which if you are on an non-visual approach could result in S-turns for you or a missed approach.  In these cases the controller often asks if you can see the aircraft so you can be given the visual clearance and manage the spacing yourself and avoid going missed. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-12T15:58:09.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24285" PostTypeId="2" ParentId="24277" CreationDate="2016-01-12T16:38:33.187" Score="6" Body="&lt;p&gt;It's certainly possible for aircraft to be retrofitted with newer engines. One example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-8 Series 70&lt;/a&gt;, which had the older JT3D engines replaced with more efficient CFM56 engines. However, there are many reasons for this process not being more common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many costs associated with changing engines. The engine may need a new nacelle design to fit the specific aircraft. This will probably require a new or at least revised strut design to mount to the wing. The wing may also need to be reinforced, as newer engines tend to be heavier. All of the systems attached to the engine, including electrical, hydraulics, and bleed air may also need changes. Avionics will also need to be updated to work with the new engine type.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Certification also should not be overlooked. Assuming the aircraft can use an existing engine that is already certified, the aircraft will still need to be certified to fly with that engine. This means a lot of paperwork with the regulators, and probably additional testing. However, engines tend to be designed for a specific aircraft type. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_LEAP&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM LEAP&lt;/a&gt; engine will power the A320, 737, and C919. All of these aircraft are similar in size and compete for the same market, yet CFM is doing testing and certification of a different version of the LEAP-1 for each of these aircraft. Each manufacturer chose to design their aircraft for a different engine version, which makes it seem unlikely that a new engine would just happen match the needs of an existing aircraft without extensive modification of the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft fuselages are designed with a limited life span. As they age, maintenance costs increase as more work is required to repair damage from fatigue and regular wear and tear. Even with new engines, the airframe would still have a limited life span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As other answers have pointed out, a new airplane design will be more efficient than just putting new engines on an old aircraft. Owners of the older aircraft would have to see a benefit in paying to upgrade their old aircraft, and having those aircraft out of service for an extended period, versus just buying a new plane that will be more efficient and will have many more flight hours left ahead of it. And some company will need to find enough of these customers to justify the large upfront costs listed above in making such an upgrade possible.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="7532" LastEditDate="2019-06-18T20:14:23.993" LastActivityDate="2019-06-18T20:14:23.993" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="24286" PostTypeId="2" ParentId="24278" CreationDate="2016-01-12T16:39:48.850" Score="7" Body="&lt;p&gt;Designing &quot;better&quot;, upgraded part is a &lt;em&gt;lot&lt;/em&gt; of work. And then everything has to be thoroughly tested to work together, which is even more work. That's why aircraft manufacturers usually choose to upgrade as &lt;em&gt;few&lt;/em&gt; parts as possible and only those where most significant benefit is expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take for example 737. The type was upgraded with new engines several times, because evolution in engine technology brought significant fuel savings. But the wings only got winglets, which was less work than redesigning the wing. And the fuselage was not changed &lt;em&gt;at all&lt;/em&gt;, only it is now built longer by adding some frames.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the situation with A320 is similar. The &quot;NEO&quot; designation for the new series entering production stands for &quot;new engine option&quot;, because that's what the upgrade is about. Beyond new engines and winglets there is basically &lt;em&gt;no other change&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And that was just &lt;em&gt;type&lt;/em&gt; changes as in &lt;em&gt;new&lt;/em&gt; aircraft being built from upgraded parts. Upgrading an existing airframe is another can of worms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the joins between airframe components have to be very strong and light. The most common joining method that satisfies this is riveting, with gluing gaining popularity for composites and in some cases welding appears (aluminium is difficult to weld, but friction-stir welding seems to work satisfactorily).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, none of these methods allows easy disassembly. To make the components replaceable, they would have to be bolted instead. However, bolts have several major disadvantages. They can shake loose, they don't fit tightly (rivets expand to fit) and they are considerably heavier. These things make them totally unsuitable for the high-stress joining, especially for joining fuselage and wings. And drilling out the rivets and riveting in a replacement is too much work and there is a high risk of damaging the parts, which could easily make them unsafe to use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then there is a question of the removed parts. So you replace the wings after half of their life, because new, more efficient model is available. But the old wings could have still generated revenue. By discarding them, you've lost those money. So to pay off, the difference in efficiency must make up for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, it is extremely unlikely to do so. The new engines of 737MAX or A320NEO save about 15% of fuel, but engines are the component where by far largest benefit could be gained. Redesigning any other component can save at most few percent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, some airframes did get structural upgrades (upgrading avionics or other small components is of course easier and thus done more often), but usually these were military aircraft where the changes provided some other benefit that was worth the effort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And some more airframes got refitted to different engines, but engines have shorter life, so they have to be designed to be replaceable. And even there it is usually military aircraft and usually only because the airframes are used much longer. For example KC-135 was reengined, but that was about the time its civilian counterpart, B707, was scrapped altogether.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But most of the time, replacing parts of an aircraft would not prevent any wastage but rather create a lot of it.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-01-12T16:39:48.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24287" PostTypeId="2" ParentId="24275" CreationDate="2016-01-12T16:57:57.373" Score="9" Body="&lt;p&gt;At the risk of just repeating information from the great answers that &lt;a href=&quot;https://aviation.stackexchange.com/a/24276/62&quot;&gt;SentryRaven&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/a/24284/62&quot;&gt;casey&lt;/a&gt; already gave, here's a real example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last night I flew the &lt;a href=&quot;http://155.178.201.160/d-tpp/1601/00697IL22.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS 22&lt;/a&gt; into &lt;a href=&quot;http://www.airnav.com/airport/KLEX&quot; rel=&quot;nofollow noreferrer&quot;&gt;KLEX&lt;/a&gt; for practice, although conditions were perfectly clear and most aircraft were using a visual approach. If it had been a 'real' flight and not practice I would certainly have taken the visual as well because it would have saved almost half an hour of flight time (and fuel):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I was inbound from the west and ATC started vectoring me when I was still more than 10 miles from KLEX to get me onto the ILS approach. They sent me northeast, east then southeast to intercept the glideslope. That means that instead of just flying 10 miles directly to join the pattern, I was vectored for almost 40 miles. Normally, you just don't want to use up that much time and fuel if you don't have to. Unfortunately I don't have track data from the flight but it looked roughly like this; even if you aren't familiar with the chart you can probably see how using the ILS required a huge diversion. The pink line is my route and the red arrow shows where the vectors started:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xTa9M.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xTa9M.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I was cleared for the ILS while about 10nm from the runway. But the winds were very high, and instead of having a ground speed of 80 or 90 knots (in a C172), I had a ground speed of 50. That meant I took about 12 minutes to land, which effectively blocked the final approach course for that amount of time. A faster aircraft on a visual approach was turned in behind me and had to do S-turns on final to avoid getting too close. If I had been on a visual approach instead, I would have been in the traffic pattern very close to the runway and would have spent just a minute or two on final.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that apart from flight time, another reason to prefer visual approaches is that a pilot (a private one, anyway) has a much lower workload. You don't have to brief the approach, set up your nav equipment (and maybe autopilot) etc.; instead, you just look outside and fly visually.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-12T16:57:57.373" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24288" PostTypeId="2" ParentId="24277" CreationDate="2016-01-12T17:04:32.940" Score="10" Body="&lt;p&gt;You are absolutely right - refitting new engines to older airplanes makes a lot of economical sense. After all, two thirds of fuel economy gains in the last 50 years were due to better engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some conditions conspire to make this harder than it might look:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The better efficiency was gained by &lt;a href=&quot;https://aviation.stackexchange.com/questions/7910/why-is-a-higher-bypass-ratio-more-efficient-at-lower-speeds&quot;&gt;increasing the bypass ratio&lt;/a&gt; of engines, which means that the new ones had more diameter for the same thrust. This makes them &lt;a href=&quot;https://aviation.stackexchange.com/questions/7824/what-is-the-reason-for-the-odd-shape-of-the-boeing-737-engine-nacelles/7825#7825&quot;&gt;hard to fit to airframes designed for the smaller engines&lt;/a&gt;, and adding a longer landing gear would be too expensive - then it is indeed better to buy a new airframe.&lt;/li&gt;&#xA;&lt;li&gt;Designs with tail-mounted engines would have center-of-gravity problems with newer, heavier engines. Tail-mounting engines was very popular after the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sud Aviation Caravelle&lt;/a&gt; pioneered this, but rules out those designs (BAC One-Eleven, Vickers VC-10, Boeing 727, Illyushin 62, DC-9, Tupolev 134 and 154) for refitting with more modern engines.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Add to this that airframes have a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9719/how-do-you-determine-how-much-life-an-aircraft-has-left&quot;&gt;limited life time&lt;/a&gt;, and fitting new engines makes sense for only a limited number of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-12T17:04:32.940" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24289" PostTypeId="1" AcceptedAnswerId="24291" CreationDate="2016-01-12T17:12:40.780" Score="12" ViewCount="1432" Body="&lt;p&gt;Consider a scenario where an airplane is operated on an ETOPS 180 route where the ETOPS alternate is open, available and above minima, but there is terrain between the route and the airport which makes it absolutely unreachable. If, in that scenario, an engine failure or decompression alternate is available but more than 180 flying minutes away, and enough fuel is carried to reach it while satisfying the terrain clearance requirements, would that flight be legal (not: practical, safe, desirable - only legal!) according to EASA/FAA regs? In other words, is ETOPS satisfied solely by looking at range circles around available airfields, or are there additional considerations required (not: prudent, desirable - required!) by regulations?&lt;/p&gt;&#xA;" OwnerUserId="10025" LastEditorUserId="3504" LastEditDate="2016-01-14T12:44:07.197" LastActivityDate="2016-01-14T12:44:07.197" Title="Is ETOPS satisfied solely by range circles?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;flight-planning&gt;&lt;easa-regulations&gt;&lt;etops&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24290" PostTypeId="2" ParentId="24278" CreationDate="2016-01-12T17:18:09.127" Score="3" Body="&lt;p&gt;Upgrading most of the items listed in the question would be considered a major change, and require approval from regulators. For an example let's just consider wings, nose, tail, engine, and fuselage. That's 5 different major sections of the plane. Even if there are only 2 options for each of those, that creates 32 unique configurations. Even if some of these can be eliminated, this is a lot of configurations. Each one would have to be approved by regulators. The manufacturers would also have to stock parts for the different options, reducing the benefit of designing, manufacturing, and installing a larger number of just one part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is good reason for having every major configuration separately certificated. Airplanes, especially airliners, are complex machines, where all of the parts interact in many ways that affect the performance and safety of the aircraft. It takes a lot of analysis and testing to fully understand all of the interactions and ensure the aircraft will perform as expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This being said, some options do have enough demand to be offered by manufacturers. Most aircraft have different fuselage options that vary in length, allowing different passenger capacities to match the needs of operators. However, cutting into the fuselage to change this would be much more expensive than just selling the plane and buying the desired size. Many aircraft also offer engine options from different manufacturers. Although compatibility is generally limited to one engine type, engines can be removed with relative ease and performance upgrades can be available. Although avionics are typically standard, there are &lt;a href=&quot;https://aviation.stackexchange.com/q/3789/1696&quot;&gt;upgrade options&lt;/a&gt; as newer technologies emerge. Seats are already a modular component that can be rearranged and swapped out and are generally chosen by each airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wings must carry the full load of the plane, and often integrate engines, landing gear, and fuel tanks. They tend to be more efficient with a larger span but aircraft are also limited in wing span, so even &lt;a href=&quot;https://aviation.stackexchange.com/q/24203/1696&quot;&gt;different sizes of the same type may use the same wings&lt;/a&gt;. Adding winglets is an option that requires much less work than replacing the whole wing for a small improvement in performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There can be different options associated with landing gear, such as different types of brakes or tire pressure monitoring. Other than that, there aren't many options to be offered. Landing gear does have a hard limit on lifespan though, so it is designed to be replaceable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail tends to be designed and sized to the aircraft, and is critical for aircraft stability and control, so is typically the same across versions of a model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as offering upgrades to major components, &lt;a href=&quot;https://aviation.stackexchange.com/q/24277/1696&quot;&gt;the benefits of such an upgrade usually do not outweigh the large costs of offering it&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-01-12T17:23:21.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24291" PostTypeId="2" ParentId="24289" CreationDate="2016-01-12T17:35:44.333" Score="14" Body="&lt;p&gt;No, ETOPS is not satisfied solely by range circles, but (among other things) by the &quot;time needed to fly to that airport&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the requirements of &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/121.633&quot;&gt;14 CFR 121.633&lt;/a&gt; (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) For ETOPS up to and including 180 minutes, no person may list an airport as an ETOPS Alternate Airport in a dispatch or flight release if &lt;strong&gt;the time needed to fly to that airport&lt;/strong&gt; (at the approved one-engine inoperative cruise speed under standard conditions in still air) would exceed the approved time for the airplane's most limiting ETOPS Significant System (including the airplane's most limiting fire suppression system time for those cargo and baggage compartments required by regulation to have fire-suppression systems) minus 15 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Paragraph (b), for ETOPS beyond 180 minutes, gives the same &quot;time needed&quot; requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if a scenario existed as the question describes where &quot;there is terrain between the route and the airport which makes [the ETOPS alternate] absolutely unreachable&quot;, then that flight could not reach that alternate in the required time (since the alternate is not reachable), and the flight could not be dispatched listing that alternate.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-12T18:20:00.580" LastActivityDate="2016-01-12T18:20:00.580" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24292" PostTypeId="1" AcceptedAnswerId="24304" CreationDate="2016-01-12T17:58:55.960" Score="12" ViewCount="1123" Body="&lt;p&gt;In another answer on SE Aviation it is mentioned that the ability to perform  Pugachev's Cobra  in a non-thrust-vectored aircraft needs &lt;em&gt;&quot;docile pitch behavior of the airframe up to approx. 110° angle of attack&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SYkhO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SYkhO.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16410/can-an-f-16-perform-pugachevs-cobra&quot;&gt;Can an F-16 perform Pugachev&amp;#39;s Cobra?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does &quot;docile pitch behavior&quot; mean in this context? Does it mean that when the control surfaces are returned to neutral the aircraft has a natural pitch down moment that returns it to its horizontal position?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, does the pilot actually have control over how long he can hold the vertical position in Pugachev's Cobra? What control surface enables him to exercise this authority in the post-stall regime when I'd have assumed the &#xA;control surfaces lack such authority? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is the holding time of the vertical attitude in Pugachev's Cobra beyond the pilot's control and only related to some sort of &quot;natural period&quot; of this maneuver in that aircraft linked to how long it takes the restoring moment to return the aircraft to its nose down attitude? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2017-02-06T09:24:37.750" Title="What is the meaning of &quot;Docile pitch behavior&quot; in the context of Pugachev's Cobra?" Tags="&lt;aerodynamics&gt;&lt;military&gt;&lt;aerobatics&gt;&lt;maneuver&gt;&lt;theory&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24293" PostTypeId="2" ParentId="24289" CreationDate="2016-01-12T19:25:23.467" Score="5" Body="&lt;p&gt;This isn't ETOPS specific, but is related to high terrain.  When overflying terrain that limits your ability to reach your destination or destination alternate you plan additional alternates called &amp;quot;drift-down&amp;quot; alternates.  The flight plan is then segmented into drift-down segments that determine which alternate you will land at if needed for that segment of flight.&lt;/p&gt;&#xA;&lt;p&gt;The drift down information will be part of the dispatch release and assures that from any point on your route with an engine failure you can  meet obstacle clearance requirements while drifting down toward a suitable alternate airport.&lt;/p&gt;&#xA;&lt;p&gt;Routes I flew between the US and Mexico often had drift-down alternates as there were areas on many of our routes that we could neither return to our departure airport or make our destination if we experienced an engine failure.  In those cases we'd reference which drift-down segment we were in and head toward the alternate for that segment.&lt;/p&gt;&#xA;&lt;p&gt;The regulatory basis for the drift-down procedures and alternates is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=71be7afc0f447126167cea92cd2efc76&amp;amp;mc=true&amp;amp;node=se14.3.121_1191&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.191&lt;/a&gt;.  The synopsis is that flight with a failed engine must be able to proceed to a destination or alternate from any point along the route while maintaining specific terrain clearance requirements.  The &amp;quot;drift-down&amp;quot; alternates must meet the same requirements as normal alternates (weather, suitability) and must be present in the dispatch release.&lt;/p&gt;&#xA;&lt;p&gt;Combining this with ETOPS, the drift-down alternates would have to be within ETOPS range in addition to the terrain drift-down requirements.&lt;/p&gt;&#xA;&lt;h3&gt;The regs:&lt;/h3&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§121.191   Airplanes: Turbine engine powered: En route limitations: One engine inoperative.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) No person operating a turbine engine powered airplane may take off that airplane at a weight, allowing for normal consumption of fuel and oil, that is greater than that which (under the approved, one engine inoperative, en route net flight path data in the Airplane Flight Manual for that airplane) will allow compliance with paragraph (a) (1) or (2) of this section, based on the ambient temperatures expected en route:&lt;/p&gt;&#xA;&lt;p&gt;(1) There is a positive slope at an altitude of at least 1,000 feet above all terrain and obstructions within five statute miles on each side of the intended track, and, in addition, if that airplane was certificated after August 29, 1959 (SR 422B) there is a positive slope at 1,500 feet above the airport where the airplane is assumed to land after an engine fails.&lt;/p&gt;&#xA;&lt;p&gt;(2) The net flight path allows the airplane to continue flight from the cruising altitude to an airport where a landing can be made under §121.197, clearing all terrain and obstructions within five statute miles of the intended track by at least 2,000 feet vertically and with a positive slope at 1,000 feet above the airport where the airplane lands after an engine fails, or, if that airplane was certificated after September 30, 1958 (SR 422A, 422B), with a positive slope at 1,500 feet above the airport where the airplane lands after an engine fails.&lt;/p&gt;&#xA;&lt;p&gt;(b) For the purposes of paragraph (a)(2) of this section, it is assumed that—&lt;/p&gt;&#xA;&lt;p&gt;(1) The engine fails at the most critical point en route;&lt;/p&gt;&#xA;&lt;p&gt;(2) The airplane passes over the critical obstruction, after engine failure at a point that is no closer to the obstruction than the nearest approved radio navigation fix, unless the Administrator authorizes a different procedure based on adequate operational safeguards;&lt;/p&gt;&#xA;&lt;p&gt;(3) An approved method is used to allow for adverse winds:&lt;/p&gt;&#xA;&lt;p&gt;(4) Fuel jettisoning will be allowed if the certificate holder shows that the crew is properly instructed, that the training program is adequate, and that all other precautions are taken to insure a safe procedure;&lt;/p&gt;&#xA;&lt;p&gt;(5) The alternate airport is specified in the dispatch or flight release and meets the prescribed weather minimums; and&lt;/p&gt;&#xA;&lt;p&gt;(6) The consumption of fuel and oil after engine failure is the same as the consumption that is allowed for in the approved net flight path data in the Airplane Flight Manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-13T14:43:10.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24294" PostTypeId="2" ParentId="23867" CreationDate="2016-01-12T19:29:25.233" Score="8" Body="&lt;p&gt;As mentioned above, this approach has no IAF.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's because the the VOR is at 1,301 MSL (note the height of the obstacle next to the VOR is 1,410), and the segment from TIVNE to HORVI descends from 2,800 to 1,340 MSL, and will dip below the usable volume of a &lt;em&gt;Low Altitude&lt;/em&gt; VOR. &lt;a href=&quot;http://webapp1.dlib.indiana.edu/virtual_disk_library/index.cgi/4300833/FID2415/ATPUBS/aim/p0101008.htm&quot; rel=&quot;noreferrer&quot;&gt;According to AIM 1-1-8&lt;/a&gt;, a &lt;em&gt;low altitude&lt;/em&gt; VOR with a standard service volume cannot be received inside 10 miles and below 1,000 feet above the NAVAID.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5W1Mb.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5W1Mb.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-13T14:40:48.770" LastActivityDate="2016-01-13T14:40:48.770" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24295" PostTypeId="2" ParentId="8580" CreationDate="2016-01-12T19:32:35.090" Score="3" Body="&lt;p&gt;Line of sight calculation is based on earth radius and height above ground of transmitter (and receiver).  R = 21000000 (21 million feet) approximately.  Based on plane trigonometry, d squared = h * (2 * R + h).  This is distance to horizon for an observer at height h above surface of radius R.  If R &gt;&gt; h then a good approximation is:&#xA;d squared = 2 * R * h;&#xA;or&#xA;d = square root (2 * R) * square root (h)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and since R is essentially fixed, we can calculate it and are left with&lt;/p&gt;&#xA;&#xA;&lt;p&gt;d = 6480 * square root (h) = 6480 h^1/2&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which gives d in feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using another approximation 1nm (nautical mile) = 6076 feet&lt;/p&gt;&#xA;&#xA;&lt;p&gt;d = 1.07 h^1/2 (h in feet above surface, d in nautical miles)&#xA;or&#xA;d = 1.23 h^1/2 (h in feet above surface, d in statute miles)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the well known formula: d = 1.25 h^1/2 is an approximation for the horizons range in statute miles when h is in feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem stated above is incomplete.  You are left with some assumptions when attempting its solution.&#xA;1) are we to assume adequate TX power and RX sensitivity to reach?&#xA;2) are we limited only be line of sight (i.e direct line between TX and RX that does not penetrate the earths surface?)&#xA;3)Should we assume the airfield height to be the height of the surface under the aircraft and at essentially all points between the two?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all these assumptions can be made (maybe there are more?) then the height of the aircraft above the ground is 1646 m = 5400 ft and d = 81 nm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that if you assume the airfield to be 335 m above ground level you will get a drastically different answer to the line of sight range.  With the aircraft at 1981 m (6500 ft) and the field at 335 m (1100 ft) then:&#xA;d1 (aircraft) = 89 ft and d2 (field) = 36 nm so d = d1 + d2 = 125nm.&lt;/p&gt;&#xA;" OwnerUserId="12974" LastActivityDate="2016-01-12T19:32:35.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24296" PostTypeId="1" AcceptedAnswerId="24300" CreationDate="2016-01-12T19:55:48.807" Score="1" ViewCount="303" Body="&lt;p&gt;Why in diagrams of a stall, the relative &quot;wind&quot; comes in horizontally no matter how the airplane is orientated? Doesn't the engine, which produces the thrust for the &quot;wind&quot;, stay parallel to the wing making the diagrams of wind at higher AoAs much more inaccurate because of the direction of thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dZHRD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dZHRD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.skybrary.aero/index.php/File:Deep_Stall.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12720" LastEditDate="2016-01-13T02:36:53.240" LastActivityDate="2016-03-31T18:56:54.380" Title="How accurate are these Stall Diagrams depictions of relative wind?" Tags="&lt;stall&gt;&lt;angle-of-attack&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24297" PostTypeId="2" ParentId="24280" CreationDate="2016-01-12T20:02:05.283" Score="3" Body="&lt;p&gt;In geometry, the point where two lines cross is an intersection, and the point where a line meets the axis (another line) is where it intercepts it.  This is likely where these terms come from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you take the current location of the aircraft and extend the current ground track (the path) to the point where it intercepts the final approach course, that intersection is where the intercept occurs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In ATC terms, when instructing a pilot &lt;strong&gt;*to intercept a course&lt;/strong&gt;, you are telling them to transition from one course to the another like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8b1Qs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8b1Qs.jpg&quot; alt=&quot;Intercept&quot;&gt;&lt;/a&gt;&#xA;&lt;sub&gt;&lt;em&gt;Credit: Own work.&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they were instructed to &lt;strong&gt;not&lt;/strong&gt; intercept the course, then they would be expected to continue on their original course (the black line in the picture above).  Note that when a final approach course is involved in this situation, to be extra clear the phrase &quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1117/what-is-the-procedure-when-being-vectored-for-an-approach-and-atc-allows-you-to&quot;&gt;vectors across final&lt;/a&gt;&quot; is used so that they do not intercept when they aren't supposed to.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-13T00:25:12.010" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24299" PostTypeId="2" ParentId="21383" CreationDate="2016-01-12T21:12:50.440" Score="3" Body="&lt;p&gt;Around the Great Lakes it is common to put &quot;NO OVERWATER&quot; if you don't want to be routed over the lakes.&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2016-01-12T21:12:50.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24300" PostTypeId="2" ParentId="24296" CreationDate="2016-01-12T21:26:30.683" Score="6" Body="&lt;p&gt;&lt;strong&gt;The diagrams are accurate.¹&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust, produced by the engine, is one of the forces acting on the airframe. The others are lift, drag and weight (a.k.a. gravity).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://www.av8n.com/how/img48/four-climb.png&quot; alt=&quot;forces on an airplane&quot;&gt;&#xA;(from &lt;a href=&quot;https://www.av8n.com/how/htm/4forces.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;How It Flies, chapter 4&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When these forces are in equilibrium, i.e. their (vector) sum is zero, the aircraft flies straight, in whatever direction it does (that is what Newton's first law says: an object remains at rest or continues to move at constant velocity unless acted upon by external force).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the forces are not in equilibrium, the aircraft &lt;em&gt;accelerates&lt;/em&gt; in the direction of their sum (that is what Newton's second law says: the sum of external forces on an object is equal its mass times its acceleration). But direction of acceleration and direction of velocity are independent. If the aircraft is turning, acceleration is to the side while velocity is (approximately) forward. If it is slowing down, acceleration is aft and velocity is still forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So thrust and direction of flight don't have to be parallel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a more practical argument, imagine an airplane doing the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tailslide&quot; rel=&quot;nofollow noreferrer&quot;&gt;tailslide&lt;/a&gt; aerobatic manoeuvre. The nose points up and the engine is running and producing thrust up. But because the thrust is less then the gravity, the aircraft slows down until it stops midair and starts to fall back to the ground, &lt;em&gt;tail first&lt;/em&gt;. So for a moment, the relative wind will come from aft while the engine is still producing forward thrust. Only then will the aircraft pitch over to restore normal airflow over the wings and return to fully controlled flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now of course since the lift and drag forces depend on the relative wind. The lift, which is the aerodynamic force perpendicular to the relative wind, increases with angle of attack, which is the angle between the relative wind and the wing planform, until stall angle of attack is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when the plane is flying level slowly, the nose is pointed up to create sufficient angle of attack. The thrust is thus pointing slightly up, so small part of it balances a bit of weight, reducing the lift requirement. That is why aircraft actually stall at slightly slower speed when the engine is developing full power than when it is stopped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read the &lt;a href=&quot;https://www.av8n.com/how/htm/4forces.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;How It Flies chapter 4&lt;/a&gt; for more details on the forces. And the rest of &lt;a href=&quot;https://www.av8n.com/how/&quot; rel=&quot;nofollow noreferrer&quot;&gt;How It Flies&lt;/a&gt;; it explains the physics pretty well.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ That is accurate regarding the direction of oncoming relative wind. They are not accurate regarding the flow around and behind the wings.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.600" LastActivityDate="2016-03-31T18:56:54.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24301" PostTypeId="2" ParentId="15733" CreationDate="2016-01-12T22:17:53.660" Score="1" Body="&lt;p&gt;Might not be relevant but here in the UK, I have been in helicopters on Search and Rescue training and missions in the mountains and you will always be belted in, whether it is by ground entry or winched up. The winchman will be attached by leash and harness as he is usually hanging around or out of the door.&lt;/p&gt;&#xA;" OwnerUserId="12977" LastActivityDate="2016-01-12T22:17:53.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24302" PostTypeId="2" ParentId="21383" CreationDate="2016-01-12T23:06:24.610" Score="1" Body="&lt;p&gt;In helicopters, IFR flights can often terminate in S-VFR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this example, one might add &quot;Request S-VFR from HELOG to Downtown&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gkYto.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gkYto.png&quot; alt=&quot;JFK Copter RNAV (GPS) 028&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-12T23:06:24.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24304" PostTypeId="2" ParentId="24292" CreationDate="2016-01-13T05:10:56.633" Score="9" Body="&lt;p&gt;&quot;Docile&quot; means no big pitching moments over the angle of attack range. Since the control power with fully stalled control surfaces is rather small, the airframe must not create strong pitching moments, but keep a small pitch-down moment so the airplane returns eventually to normal angles of attack which allow regular flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maneuver is dynamic, so the pilot needs to build up a specific pitch rate. Inertia will keep the aircraft pitching up, and the small pitch-down moment (and aerodynamic damping) will reduce the pitch rate so that the pitch-up stops when the nose is pointing straight up. What follows is the consequence of the small pitch-down moment: The aircraft slowly returns to controlled flight, and once control authority is re-established, the pilot stops the pitching motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By selecting the initial pitch rate, the pilot can control the maximum angle of attack, but once he leaves the flight regime of attached flow, he has to wait until inertia and aerodynamics do their part.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-13T05:10:56.633" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="24305" PostTypeId="1" CreationDate="2016-01-13T05:37:28.590" Score="-5" ViewCount="257" Body="&lt;p&gt;What are the major differences in between the flying of, say, a drone like the Predator, versus the QF-16? What changes so drastically in the handling of the aircraft for the remote pilot? Are the increased maximum speed and loading the only thing that makes this flight different?&lt;/p&gt;&#xA;" OwnerUserId="3142" LastEditorUserId="3504" LastEditDate="2016-01-14T12:44:41.987" LastActivityDate="2016-01-14T12:44:41.987" Title="QF-16 vs Predator" Tags="&lt;military&gt;&lt;unmanned-aerial-vehicle&gt;&lt;f-16&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2016-01-19T03:41:00.603" ContentLicense="CC BY-SA 3.0" />
  <row Id="24306" PostTypeId="2" ParentId="24305" CreationDate="2016-01-13T06:46:27.463" Score="1" Body="&lt;p&gt;USAF has been flying combat aircraft converted into target drones for decades; calling it the next big step is a few decades too late. The best possible explanation would be that the buzz was created in context of the armed UAVs being used in combat operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the strictest sense, the differences in the two platforms are the same as the aircraft they are based on. QF-16 is based on a combat aircraft and as such brings to the table advantages like maneuverability, speed etc and corresponding limitations. On the other hand, the Predator (MQ-1) is based on a reconnaissance platform and brings the advantages like endurance, quietness etc. while limited by payload and speed. The handling qualities vary accordingly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another dimension is the use of experience gained in designing/operating QF-16 in the development of next generation combat aircraft which are expected to be optionally piloted (for e.g. the preflight tests on QF-16 are carried out by a pilot, who then exits the aircraft).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-13T06:46:27.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24307" PostTypeId="1" AcceptedAnswerId="24327" CreationDate="2016-01-13T08:01:12.843" Score="3" ViewCount="880" Body="&lt;p&gt;For a handheld VHF radio carried as an emergency backup, how should I expect the effective radius of a handheld radio to compare with on-board radios in two-way communications? I figure reception should be the same. But transmission would probably be different, dependent on the power. Would the difference be significant? What factors would change the useful radius of a handheld radio?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12720" LastEditDate="2016-01-13T15:23:24.983" LastActivityDate="2016-01-13T17:34:03.143" Title="What is the expected range of handheld radio?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;radio&gt;&lt;lost-communications&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24308" PostTypeId="2" ParentId="24242" CreationDate="2016-01-13T08:14:17.327" Score="4" Body="&lt;p&gt;The question as asked is open to interpretation, so I will first rephrase it to have a basis to build upon. Your last paragraph tells me that you want to know the optimum bank angle to get the highest ratio of turn rate to altitude loss in a glide at a given airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoiler: Since steeper bank angles require more lift, and aircraft with better L/D are more efficient in producing lift, the optimum bank angle depends on the aerodynamic qualities of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What is given&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Glider or powered aircraft with inoperative engine. The polar and the weight are known and do not change over time.&lt;/li&gt;&#xA;&lt;li&gt;Airspeed. This will result in a restricted optimum - the absolute best bank angle will require a suitable speed.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;What can be changed&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Bank angle &lt;span class=&quot;math-container&quot;&gt;$\varphi$&lt;/span&gt; (obviously - you are asking for this)&lt;/li&gt;&#xA;&lt;li&gt;Lift &lt;span class=&quot;math-container&quot;&gt;$L$&lt;/span&gt; (again, obviously. You want to stay airborne)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Solution&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First I need to formulate the ratio of turn rate over height loss. This then needs to be derived with respect to the bank angle and set to zero. To have a derivable polar, I use the quadratic polar where &lt;span class=&quot;math-container&quot;&gt;$c_D = c_{D0}\cdot\frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$&lt;/span&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I further assume a coordinated turn, so we can define the lift and drag equations. Drag is compensated by selecting a suitable glide path angle &lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt; in order to convert potential into kinetic energy to keep the speed constant. The angular velocity &lt;span class=&quot;math-container&quot;&gt;$\Omega$&lt;/span&gt; in a turn with the radius &lt;span class=&quot;math-container&quot;&gt;$R$&lt;/span&gt; is&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\Omega = \frac{v}{R} = \frac{g\cdot tan\varphi}{v} = \frac{g\cdot \sqrt{n_z^2-1}}{v}$$&lt;/span&gt;&#xA;Height loss over time is vertical speed &lt;span class=&quot;math-container&quot;&gt;$v_z$&lt;/span&gt;, and this can be calculated from speed &lt;span class=&quot;math-container&quot;&gt;$v$&lt;/span&gt; and flight path angle &lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt;:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$v_z = v\cdot sin\gamma$$&lt;/span&gt;&#xA;Since &lt;span class=&quot;math-container&quot;&gt;$v$&lt;/span&gt; is given and constant, we can rephrase the problem as a maximization of turn rate over flight path angle or sink speed. This is equivalent to the smallest height loss for a given azimuth change.&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\frac{\Omega}{v_z} = \frac{g\cdot tan\varphi}{sin\gamma}$$&lt;/span&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before deriving this, we need to express &lt;span class=&quot;math-container&quot;&gt;$\gamma$&lt;/span&gt; in terms of &lt;span class=&quot;math-container&quot;&gt;$\varphi$&lt;/span&gt;. If we had the liberty to adjust speed, we could directly solve for the optimum bank angle at optimum L/D. Now, however, speed is fixed and L/D is what the airplane produces at the required lift. Since for gliders &lt;span class=&quot;math-container&quot;&gt;$sin\gamma = \frac{c_D}{c_L}$&lt;/span&gt;, we can write:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\frac{\Omega}{v_z} = \frac{g\cdot tan\varphi\cdot c_L}{c_{D0}+\frac{c_L^2}{\pi\cdot AR\cdot\epsilon}} = \frac{g\cdot sin\varphi\cdot \frac{m\cdot g}{q\cdot S}}{c_{D0}\cdot cos^2\varphi + \frac{\left(\frac{m\cdot g}{q\cdot S}\right)^2}{\pi\cdot AR\cdot\epsilon}}$$&lt;/span&gt;&#xA;with &lt;span class=&quot;math-container&quot;&gt;$c_L = \frac{m\cdot g}{q\cdot S\cdot cos\varphi}$&lt;/span&gt;. Since the dynamic pressure &lt;span class=&quot;math-container&quot;&gt;$q$&lt;/span&gt; is constant, we can now derive with respect to the bank angle. With the chain rule we get a fraction, and since it will be set to zero, it is enough to look for the condition when the numerator is zero:&#xA;&lt;span class=&quot;math-container&quot;&gt;$$g\cdot cos\varphi\cdot \frac{m\cdot g}{q\cdot S}\cdot\left({c_{D0}\cdot cos^2\varphi + \frac{\left(\frac{m\cdot g}{q\cdot S}\right)^2}{\pi\cdot AR\cdot\epsilon}}\right) = g\cdot sin\varphi\cdot \frac{m\cdot g}{q\cdot S}\cdot 2\cdot c_{D0}\cdot sin\varphi\cdot cos\varphi$$&lt;/span&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\frac{\left(\frac{m\cdot g}{q\cdot S}\right)^2}{c_{D0}\cdot\pi\cdot AR\cdot\epsilon} = 2\cdot sin^2\varphi - cos^2\varphi = \frac{1}{2} - \frac{3}{2}cos2\varphi$$&lt;/span&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$$\varphi = \frac{1}{2}\cdot arccos\left(\frac{1}{3} - \frac{2\cdot\left(\frac{m\cdot g}{q\cdot S}\right)^2}{3\cdot c_{D0}\cdot\pi\cdot AR\cdot\epsilon}\right)$$&lt;/span&gt;&#xA;This does not obviously look wrong, but I could very well have screwed up on the path to the result. If you plug in the numbers for an airplane you know, you can check whether the result makes sense. At least, with too low airspeed you get a negative argument for the cosine which mathematically means a roll angle of &gt;90° and can be interpreted as too slow for that turn.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we got a &lt;a href=&quot;https://aviation.stackexchange.com/questions/68263/what-bank-angle-creates-the-least-energy-loss-in-an-emergency-engine-out-180-deg&quot;&gt;similar question&lt;/a&gt; but with both speed and roll angle as variables. Obviously, now we need to derive both with respect to speed &lt;strong&gt;and&lt;/strong&gt; roll angle. But it is more fun to plot the results over these two as a contour plot. I just had to do this since several answers here claim that the optimum angle is 45°. Equally obviously, this is too simplistic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First the math: I start from the same equations as above and added a term for wind (&lt;span class=&quot;math-container&quot;&gt;$w_z$&lt;/span&gt;) which adds rising or sinking air mass to the problem. &#xA;&lt;span class=&quot;math-container&quot;&gt;$$∆h = \frac{\pi\cdot v}{g\cdot tan\phi}\cdot(v_z+w_z) = \frac{\pi\cdot v}{g\cdot\sqrt{n_z^2-1}}\cdot\left(\frac{v\cdot c_D}{c_L}+w_z\right)$$&lt;/span&gt;&#xA;Expressing the lift coefficient as &lt;span class=&quot;math-container&quot;&gt;$$c_L = \frac{2\cdot n_z\cdot m\cdot g}{\rho\cdot S\cdot v^2}$$&lt;/span&gt;&#xA;brings us to &lt;span class=&quot;math-container&quot;&gt;$$∆h = \frac{\pi}{g^2\cdot\sqrt{n_z^2-1}}\cdot \left(\frac{\rho\cdot S\cdot v^4\cdot c_{D0}}{2\cdot n_z\cdot m} + \frac{2\cdot n_z\cdot m\cdot g^2}{\pi\cdot\rho\cdot S\cdot AR\cdot\epsilon} + w_z\cdot v\cdot g\right)$$&lt;/span&gt;&#xA;Nomenclature:&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm g\kern6mm$&lt;/span&gt;gravitational acceleration&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm n_z\kern4mm$&lt;/span&gt;vertical load factor&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm \rho\kern6mm$&lt;/span&gt;air density&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm S\kern5mm$&lt;/span&gt;wing area&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm v\kern6mm$&lt;/span&gt;flight speed&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm c_{D0}\kern2mm$&lt;/span&gt;zero-lift drag coefficient&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm m\kern5mm$&lt;/span&gt;aircraft mass&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm AR\kern1mm$&lt;/span&gt;wing aspect ratio&lt;br&gt;&#xA;&lt;span class=&quot;math-container&quot;&gt;$\kern4mm \epsilon\kern6mm$&lt;/span&gt;Oswald factor&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The figure below is the result plotted in R. Since I need to read the full matrix of values for the contour plot, the area of low speed and high bank angle is filled with the result of a strict penalty function, so please disregard the values to the right and below the red line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Tiegv.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tiegv.png&quot; alt=&quot;Contour plot of height losses a A320 type aircraft in a 180° turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contour plot of height losses a A320 type aircraft in a 180° turn at sea level and MTOW (78 tons), no wind. X is bank angle in degrees and Y is flight speed in m/s. Own work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see, the minimum (approx. 170 m) is achieved right before stall at a high bank angle and speed. Unfortunately, you need the aerobatic version of the A320 to fly this safely.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-09-01T21:19:21.333" LastActivityDate="2019-09-01T21:19:21.333" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="24309" PostTypeId="1" AcceptedAnswerId="24323" CreationDate="2016-01-13T10:16:40.377" Score="20" ViewCount="3679" Body="&lt;p&gt;Do airlines have to get permission from the FAA to change their livery? It would be great if someone can throw in some examples where this has happened.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="6886" LastEditDate="2016-01-14T01:16:04.903" LastActivityDate="2016-01-14T01:16:04.903" Title="Do airlines have to get permission from the FAA if they want to change their livery?" Tags="&lt;faa-regulations&gt;&lt;faa-approval&gt;&lt;livery&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24311" PostTypeId="2" ParentId="22567" CreationDate="2016-01-13T11:27:35.753" Score="1" Body="&lt;h2&gt;It doesn't need to be updated&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It already does everything the Marines need it to do. Replacing it would be expensive for no reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other aircraft you mention, F-15, F-16, F-35, F-22 are a little different - the F-35 is replacing the F-18/F-16. The F-18 replaced the F-14. The F-22 is mostly a replacement for the F-15. Why? Because these get outdated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USAF's potential enemies build a fighter that can beat the F-15, so you build a fighter that can beat their new one. Repeat. This has happened since the dawn of the fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transport aircraft, however... what would you improve? It's already about as fast as it's going to get without a lot of money being spent, and as capable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quite simply, there's no need to replace it yet. That doesn't mean it's been unsuccessful.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-01-13T11:27:35.753" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24312" PostTypeId="1" CreationDate="2016-01-13T11:29:17.030" Score="0" ViewCount="2247" Body="&lt;p&gt;Can someone please explain citing an example Aircraft an approximate breakdown  of the cost incurred in developing each part of the aircraft( fuselage, engine choices) and other things like certification that allow it to be sold to the public. Preferably an example of a plane with a clean sheet design like the Concorde which was nothing like other planes of the time.&lt;/p&gt;&#xA;" OwnerDisplayName="user12782" LastEditorUserId="167" LastEditDate="2016-01-14T01:49:01.120" LastActivityDate="2016-01-14T01:49:01.120" Title="What's the breakdown of total development cost for the various components of an aircraft?" Tags="&lt;aircraft-design&gt;&lt;cost&gt;&lt;new-airplane&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2016-01-14T12:38:48.150" ContentLicense="CC BY-SA 3.0" />
  <row Id="24313" PostTypeId="2" ParentId="24309" CreationDate="2016-01-13T11:29:46.487" Score="3" Body="&lt;p&gt;A short answer, but: &lt;strong&gt;No&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can paint their planes pretty much however they want. I imagine various agencies and their customers would have something to say about it if they did something outrageous, but they can repaint their planes without asking permission or even informing the FAA.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-01-13T11:29:46.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24314" PostTypeId="2" ParentId="24309" CreationDate="2016-01-13T11:53:09.843" Score="13" Body="&lt;p&gt;In general, the aircraft owners can paint the aircraft whichever the way they want. However, changing of aircraft liveries comes under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#ap14.1.43_117.a&quot;&gt;refinishing of decorative coatings&lt;/a&gt; has to be done by certified personnel as it is considered major maintenance. The materials used should comply to the applicable safety regulations.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-13T11:53:09.843" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24316" PostTypeId="1" CreationDate="2016-01-13T13:10:54.653" Score="3" ViewCount="153" Body="&lt;p&gt;I am from Brazil. My crew and I will fly to France, Portugal and Switzerland. I am accustomed to flying to the USA, but it will be my first time to Europe, and I am studying the differences. Which documents and manuals do you recommend that I study and read? (Note: I want names not resource location)&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="45534" LastEditDate="2021-03-22T07:24:36.303" LastActivityDate="2021-03-22T07:24:36.303" Title="Which manuals should I study before flying to France, Portugal and Switzerland?" Tags="&lt;regulations&gt;&lt;caa-uk-regulations&gt;&lt;eu&gt;&lt;france&gt;&lt;rules-of-the-air&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="24317" PostTypeId="2" ParentId="786" CreationDate="2016-01-13T13:47:54.407" Score="1" Body="&lt;p&gt;There are two factors which none of the answers above capture:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Don't stall/spin the airplane. This is the #1 risk factor.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Where are you relative to the end of the runway when the engine fails?  If you have taken off in the first 500 ft of a 5,000 foot runway, and you lose a lot of altitude in a successful 180-210 degree turn, you will still be able to land on the last 4,500 ft, and maybe even need to slip if there's a strong enough tailwind. If its a short runway with an overrun or airport protection area, you might land short but without any substantial obstacles. If you took off from a sandbar in a river, you will probably find yourself wheels down, but in the drink.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-13T13:47:54.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24318" PostTypeId="1" AcceptedAnswerId="24324" CreationDate="2016-01-13T14:51:29.243" Score="9" ViewCount="1538" Body="&lt;p&gt;As I was looking at &lt;a href=&quot;https://flightaware.com/resources/airport/KCXY/ALL/all/pdf&quot; rel=&quot;noreferrer&quot;&gt;the approach charts for KCXY&lt;/a&gt; while answering &lt;a href=&quot;https://aviation.stackexchange.com/questions/23867/why-is-radar-required-on-some-faa-instrument-approaches/24294#24294&quot;&gt;this question&lt;/a&gt;, I realized that the GPS &quot;overlay-style&quot; approach to RW8 also requires RADAR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the HAR VOR isn't even shown on this Approach, and it has an IF, why should RADAR be required?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the RNAV (GPS) RWY 26 approach to this airport does not require radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qC70S.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qC70S.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2018-02-05T22:37:12.853" Title="Why does this GPS approach say &quot;RADAR REQUIRED&quot;?" Tags="&lt;avionics&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24320" PostTypeId="1" AcceptedAnswerId="24329" CreationDate="2016-01-13T15:13:13.717" Score="10" ViewCount="1819" Body="&lt;p&gt;One of the errors for a pitot tube is 'compressibility.' However, I don't understand this in detail. I get that the ASI will read slower because the ram air is compressing against the air already in the pitot tube. My question is when does this happen? What would cause this?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-01-13T17:08:18.323" LastActivityDate="2016-01-13T18:38:31.967" Title="When is compressibility a problem for a pitot tube?" Tags="&lt;aerodynamics&gt;&lt;pitot-static&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24323" PostTypeId="2" ParentId="24309" CreationDate="2016-01-13T16:08:34.937" Score="45" Body="&lt;p&gt;Not the FAA, but the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the parts are composite, only a small range of colors may be approved, depending on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Glass_transition#Transition_temperature_Tg&quot;&gt;glass transition temperature&lt;/a&gt; of the resin matrix. For gliders, only white is allowed for most of the surface area, and similarly composite parts of airliners must be painted &lt;a href=&quot;http://www.onlineamd.com/article/amd-0911-composite-repair-durability&quot;&gt;in a light color&lt;/a&gt; so they don't heat up too much in sunlight. Curiously, the lower surface has the most restrictions, because here the reflected light from a concrete surface and the restricted ventilation create the highest surface temperatures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, the UV absorption capability, moisture protection characteristics and the chemical stability of the paint when in contact with aviation fuel, hydraulic fluids, de-icing fluids and other solvents is important. Composite gliders must use a special topcoat which is more brittle than the composite structure, so cracks will show up. Airliners may use more flexible paints, but must then undergo regular inspections of their composite parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Metal surfaces are less demanding and can be painted in any color. Only the area in front of the windshield should be dark enough to reduce glare and irritating reflections.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-13T22:23:23.360" LastActivityDate="2016-01-13T22:23:23.360" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24324" PostTypeId="2" ParentId="24318" CreationDate="2016-01-13T16:17:23.787" Score="8" Body="&lt;p&gt;The immediate reason seems to be that for RNAV approaches that start at an IF (&lt;em&gt;Intermediate Fix&lt;/em&gt;) - not an IAF (&lt;em&gt;Initial Approach Fix&lt;/em&gt;) - radar is required per the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATC orders&lt;/a&gt; (4-8-1h):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;issue approach clearance [...] only after the aircraft is:  &lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;Established on a heading or course direct to the IF at an angle not greater than 90 degrees, provided the following conditions are met:&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Radar monitoring is provided to the IF.&lt;br&gt;&#xA;  (c) The SIAP must identify the intermediate fix with the letters “IF.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://155.178.201.160/d-tpp/1601/00187R26.PDF&quot; rel=&quot;noreferrer&quot;&gt;RNAV 26 approach&lt;/a&gt; that you mentioned does have an IAF, so according to the same rules radar isn't always required for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might now ask, why is radar required for RNAV approaches that start at an IF? Because, it doesn't have an IAF. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next question is why doesn't it have an IAF? Probably because of higher terrain north of the approach corridor? Or maybe (as per @Jonathan Walter's answer) there is sufficient Radar coverage to vector to the IF, so it doesn't need an IAF.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="3504" LastEditDate="2016-01-13T19:09:45.973" LastActivityDate="2016-01-13T19:09:45.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24325" PostTypeId="2" ParentId="24312" CreationDate="2016-01-13T16:17:34.477" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-885j-aircraft-systems-engineering-fall-2004/lecture-notes/pres_willcox.pdf&quot; rel=&quot;nofollow&quot;&gt;This Powerpoint&lt;/a&gt; has some pretty solid data in it in terms of the general relationship of cost to sales and what not. In the end of the day you simply cant find these numbers unless the company is willing to share them (which they generally are not). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://www.prgs.edu/content/dam/rand/pubs/reports/2007/R761.1.pdf&quot; rel=&quot;nofollow&quot;&gt;very dated paper from the airforce&lt;/a&gt; that also talks a bit about what you are looking for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.quora.com/Aircraft/How-much-does-it-cost-to-design-and-develop-a-very-light-jet-personal-jet&quot; rel=&quot;nofollow&quot;&gt;poorly cited answer states its cost Cirrus $150,000,000&lt;/a&gt; to develop their new Vision Jet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;A few side notes&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The Concorde is not a great example of developing an airplane when it comes to cost analysis. BAE (the company that designed and built it, was BAC at the time) had most of their cost undercut by the British and French Governments at the time. The program cost an &lt;a href=&quot;http://www.telegraph.co.uk/news/uknews/1352927/Is-this-the-end-of-the-Concorde-dream.html&quot; rel=&quot;nofollow&quot;&gt;estimated 1.3 Billion Pounds Sterling&lt;/a&gt; and was as much about national pride as it was building a fast plane. You can find some &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot; rel=&quot;nofollow&quot;&gt;great info on it here (48:20)&lt;/a&gt;.   &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Older airframes like the Cessna 172 right on up through the Boeing 737 were built and certified in a very different time. Regulations were different and generally looser. As such it would be useless to compare the cost to get a type certificate when these planes came out with getting one today. At the same time these planes are both still in production. For what its worth the cost of keeping that type certificate up could be brought into the equation. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-01-13T16:17:34.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24326" PostTypeId="2" ParentId="22567" CreationDate="2016-01-13T16:41:27.130" Score="1" Body="&lt;p&gt;I'd argue that it's been quite successful.  Think various comments have cleared that up, as well as modifying your definition of &quot;successful.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A necessary forerunner to it was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_XV-15&quot; rel=&quot;nofollow&quot;&gt;XV-15&lt;/a&gt;.  Yes, there were earlier aircraft, but this didn't work well until smaller turboprop engines, with sufficient power density became available.  Prior to that, the engines were usually located in the fuselage and had driveshafts carrying the power to the nacelles on the wingtips.  These were heavy and prone to failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why the Osprey has props/rotors instead of jets, let's talk about thrust and power.  To get off the ground, you need more thrust than you have weight.  Typically, if you're going to do VTOL, you need 110% as much.  So a 2,000 pound aircraft needs at least 2,200 pounds of thrust to takeoff vertically, much less hover.  Hover requires even more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are multiple ways to make thrust:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;grab a relatively small amount of air mass and accelerate the heck out of it.  This is what turbojets and afterburning low-bypass turbofans do, as found in most fighter planes.  There will be high-speed jet efflux, high temperatures and comparatively high fuel consumption with this route.  The Harrier does this, as does the F-35B.  Neither can do it for very long, though (significant fuel consumption), and you don't want to be anywhere nearby, on the ground, when they do it (noisy, windy, hot).  If you need to go FAST, you need to do this.&lt;/li&gt;&#xA;&lt;li&gt;grab a relatively large amount of air mass and accelerate it a little bit.  This is what the rotor does on a helicopter and, to a lesser degree, a propeller on an airplane.  The rotor/prop wash has nowhere near the intensity of a jet engine's exhaust.  There's also less heat and much less fuel consumption.  But you can't go as fast (speed is limited by the airspeed of the rotor/prop wash).&lt;/li&gt;&#xA;&lt;li&gt;somewhere in between.  High bypass turbofans on modern jetliners grab more air than turbojets, but less than props/rotors, and they accelerate the air more than a prop/rotor but less than a turbojet.  Lower fuel consumption than the turbojet and less noise but higher speed than a prop/rotor.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If they could've done it with a single rotor, and found a way to angle that forward for &quot;airplane&quot; mode, they'd have done so; a single, large rotor would be more efficient than a pair of smaller rotors.  The simplest mechanism they could develop, which would provide the capabilities of both airplane and helicopter, was a twin-engine design.  You get a faster cruise speed and a longer range than any helicopter in the inventory and a broader flight envelope than any airplane (VTOL and hover).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, you need a degree of agility for maneuvering in hover.  So you need the ability to change the thrust vectors while hovering; the &quot;airplane&quot; flight controls (ailerons, elevators and rudder) are useless in this mode.  To accomplish this, the props/rotors have collective and cyclic controls like a helicopter.  If you flatten the pitch on the forward part of the rotation, that will change the thrust vector to push down-and-aft, instead of just down.  Coordinate this between the two engines and you have translation forward/aft, side-to-side and pivot, just like a helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To my knowledge, no one has succeeded in making a jet engine which can do this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet-engined variant would likely need some kind of 2D thrust vectoring, downstream of the actual engine.  There are existing examples of this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow&quot; title=&quot;F-22&quot;&gt;F-22&lt;/a&gt; does 1D thrust vectoring (each engine nozzle can pitch up/down).  Used differentially, this can augment pitch AND roll.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-35&quot; rel=&quot;nofollow&quot; title=&quot;Su-35&quot;&gt;Su-35&lt;/a&gt; does something similar to the F-22&lt;/li&gt;&#xA;&lt;li&gt;The F-35B, as mentioned, does limited 1D thrust vectoring for STOVL&lt;/li&gt;&#xA;&lt;li&gt;Some advanced &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29M&quot; rel=&quot;nofollow&quot; title=&quot;Mig-29s&quot;&gt;Mig-29s&lt;/a&gt; do full 2D thrust vectoring with both nozzles&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Dynamics_F-16_VISTA&quot; rel=&quot;nofollow&quot; title=&quot;F-16 VISTA&quot;&gt;F-16 VISTA&lt;/a&gt; demonstrator did full 2D thrust vectoring&lt;/li&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell-MBB_X-31&quot; rel=&quot;nofollow&quot; title=&quot;X-31&quot;&gt;X-31&lt;/a&gt; also had basic 2D thrust vectoring, due to some deflector &quot;paddles&quot; aft of the engine.  This is similar to the directional vanes used on the original V-2 rocket.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Assuming someone can come up with a usable 2D thrust vectoring system, mounted to the aft end of high-bypass turbofan (all the mentioned examples are turbojets, lower-bypass turbofans or rockets), it might be possible to do a jet-powered variant, at some point in the future.&lt;/p&gt;&#xA;" OwnerUserId="2859" LastEditorUserId="2859" LastEditDate="2016-01-13T23:26:23.687" LastActivityDate="2016-01-13T23:26:23.687" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24327" PostTypeId="2" ParentId="24307" CreationDate="2016-01-13T17:34:03.143" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.icomamerica.com/en/products/avionics/handheld/a24/specifications.aspx&quot; rel=&quot;nofollow&quot;&gt;This ICOM hand held&lt;/a&gt; has a max output of 5W compared with their &lt;a href=&quot;http://www.icomamerica.com/en/products/avionics/panelmount/a210/specifications.aspx&quot; rel=&quot;nofollow&quot;&gt;panel mount radio which outputs at 8W&lt;/a&gt;. Unfortunately they don't quote effective ranges on their website (and its highly dependent on many factors anyway). In any case you are limited by line of sight which depending on the plane you are flying (and how high up you are) may be more of an issue. There is some &lt;a href=&quot;http://www.pilotsofamerica.com/forum/showthread.php?t=39154&quot; rel=&quot;nofollow&quot;&gt;discussion here on the matter&lt;/a&gt; and generally people say the work pretty well. Keep in mind also that the aircrafts installed radios have their antenna that are mounted on the exterior of the plane which has an effect on the reception and transmission ability. Using a hand held inside a plane may in practice yield different results even if it has the same transmission specs as an installed radio. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-01-13T17:34:03.143" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24328" PostTypeId="1" AcceptedAnswerId="24342" CreationDate="2016-01-13T18:16:16.050" Score="14" ViewCount="5295" Body="&lt;p&gt;As a passenger on A321 I have recently experienced the following: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane took off in strong winds (25-30 knots) and then proceeded to the destination, which it reached in 45 minutes. At first attempt the plane touched the ground with its rear landing gear and then it immediately went full throttle and took off again. After making a circle, the situation repeated after which we flew back to the original port. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot said: &quot;I made the decision to go back because the wind is over 100 km/h, which is above this aircraft limits&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;100 km/h is over 53 knots which is way above the limitations of A321.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crosswind - Takeoff 29 kts&lt;br&gt;&#xA;Crosswind - Landing 33 kts&lt;br&gt;&#xA;Crosswind with Gusts 38 kts&lt;br&gt;&#xA;Tailwind - Takeoff and Landing 10kts&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My questions are: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Should the pilot have even attempted to land? Wasn't it too risky? &lt;/li&gt;&#xA;&lt;li&gt;Should he have even taken off knowing about the weather conditions at the destination airport? How is this kind of decision normally made? &lt;/li&gt;&#xA;&lt;li&gt;Since takeoff limits are lower than landing, was it safe take back off upon unsuccessful landing attempt? In other words if the winds are bad enough for landing do you want to take off rather than force the plane down and see what happens?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12988" LastEditorUserId="4197" LastEditDate="2016-01-14T13:58:14.257" LastActivityDate="2020-02-28T15:37:28.893" Title="A321 Two unsuccessful strong crosswind landing attempts. What was actually going on?" Tags="&lt;landing&gt;&lt;airbus-a320&gt;&lt;crosswind&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24329" PostTypeId="2" ParentId="24320" CreationDate="2016-01-13T18:38:31.967" Score="3" Body="&lt;p&gt;In subsonic flow, a pitot tube measures the total pressure $P_{0}$, while a static port measures the static pressure $P$. For very small Mach numbers, we can use the incompressible form of Bernoulli's Equation for determining the speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As there is no energy due to compressibility, the density $\rho$ is constant. This means that along a streamline, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{P}{\rho} + \frac{1}{2} v^{2} + gh = constant$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neglecting gravity, we have, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{P}{\rho} + \frac{1}{2} v^{2} = constant$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using this, we can determine the velocity as &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$v = \sqrt{2\frac{P_{0}-P}{\rho}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This equation, however does not take the effect of comprehensibility into account. While at low speeds this is not a problem, this causes an error as the Mach number increases above ~0.3. As the speed increases above this value, the term $\frac{1}{2}\rho v^{2}$ no longer gives the difference between the Total and static pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of compressible flow, neglecting gravity we have,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\int_{P_{0}}^{P}\frac{dP}{\rho} + \frac{1}{2} v^{2} = constant$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;along the streamline as $\rho$ is no longer constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For adiabatically expanding gas, we have, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac{P_{0}}{P} = (1 + \frac{\gamma-1}{2} M^{2})^{\frac{\gamma}{\gamma - 1}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\gamma$ is the specific heat constant and $M$ is the mach number. In this case, the velocity can be calculated as,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$v = \sqrt{\frac{2 \gamma}{\gamma - 1} \frac{P}{\rho} [\frac{P_{0}}{P}^{\frac{\gamma - 1}{\gamma}}-1]}$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This difference gives rise to the error, which is positive i.e. compressibility error produces ASI readings that are too high. In terms of the pressure ratio, the error is more than 8% as the aircraft approaches transonic speeds. The following image shows the difference in pressure ratio between readings using assumptions of incompressible and compressible flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yxuEO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yxuEO.png&quot; alt=&quot;Compressibility&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Mechanical Measurements and Metrology - Measurement of Fluid Velocity&lt;/em&gt; by S. P. Venkateshan&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, the issue is with the assumptions in the method use to calculate the velocity- for low speeds, we assume that the density is constant, which is clearly not the case as the speed increases. Usually, M = 0.3 is taken as the cutoff point.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-13T18:38:31.967" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24330" PostTypeId="2" ParentId="24305" CreationDate="2016-01-13T19:04:47.717" Score="0" Body="&lt;p&gt;Another consideration in the difference might be latency as discussed in &lt;a href=&quot;https://aviation.stackexchange.com/q/21352/8730&quot;&gt;this question&lt;/a&gt;. I'm just guessing that a target drone would be flown from somewhere near the location of the exercise. As opposed to half a world away like the predator.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-13T19:04:47.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24331" PostTypeId="1" CreationDate="2016-01-13T19:05:20.433" Score="6" ViewCount="383" Body="&lt;p&gt;(Related to, but hopefully not a dupe of, &lt;a href=&quot;https://aviation.stackexchange.com/q/21953/62&quot;&gt;this question&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The latest &lt;a href=&quot;http://asrs.arc.nasa.gov/publications/callback/cb_432.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA ASRS newsletter&lt;/a&gt; includes the case of an A320 crew that forgot to retract the gear and started detailed troubleshooting without noticing that the gear was still down. The captain said in his report that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I instructed the First Officer to coordinate landing at the divert&#xA;  airport while I briefed the Lead Flight Attendant and then performed&#xA;  the Airframe Vibration Checklist&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The mention of an airframe vibration checklist caught my attention because it's such a specific scenario. So, excluding &lt;a href=&quot;https://aviation.stackexchange.com/q/21953/62&quot;&gt;normal operations&lt;/a&gt;, how many checklists does a typical airliner (like the A320) have for unusual/abnormal/emergency scenarios?&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2017-10-29T05:49:57.220" Title="How many emergency/abnormal checklists are there for a typical airliner?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;checklist&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24332" PostTypeId="2" ParentId="24328" CreationDate="2016-01-13T19:38:52.397" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Should the pilot have even attempted to land? Wasn't it too risky?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ultimately this is the decision of the pilot in command. While airlines have operating procedures (and the pilot can be reprimanded for not following them) the pilot can for any number of reasons attempt a landing, we can spend a lot discussing decision making but my guess is that the pilot felt the conditions were safe to make an attempt at a landing. The problem he encountered (most likely) is that high winds are often accompanied by things like turbulence or &lt;a href=&quot;https://aviation.stackexchange.com/questions/22978/what-wind-change-gradient-is-necessary-to-be-classified-as-wind-shear&quot;&gt;wind shear&lt;/a&gt; which can make landing dangerous in its own right. Upon his attempt to land he encountered this and decided a go-around and then eventual diversion was the safe choice.     &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Should he have even taken off knowing about the weather conditions at&#xA;  the destination airport? How this kind of decision is normally made?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes you do know the conditions when you depart however those are the conditions at the time of departure. Weather can change fast (even in 45 minutes). You could have departed with wind well within limitations and had it unexpectedly kick up. The most tragic and common example of this is VFR rated pilots who depart and encounter IMC in route which often unfortunately leads to accidents.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Since takeoff limits are lower than landing, was it safe take back off&#xA;  upon unsuccessful landing attempt? In other words if the winds are bad&#xA;  enough for landing do you want to take off rather than force the plane&#xA;  down and see what happens?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The limits you have listed are direct &lt;a href=&quot;https://aviation.stackexchange.com/questions/17302/are-pilots-generally-trained-for-crosswind-landings/17311#17311&quot;&gt;cross wind&lt;/a&gt; limits, in other words the wind is &lt;a href=&quot;https://en.wikipedia.org/wiki/Crosswind&quot; rel=&quot;nofollow noreferrer&quot;&gt;moving across the runway (90 degrees to the direction of the runway)&lt;/a&gt;. There is generally no published headwind limit for landing (wind blowing down the runway). There is however a practical limit in the sense that if the wind speed is higher than the maximum speed of the aircraft you will not be able to approach the runway (and will move backwards relative to the ground). This is not really an issue for large planes but for something like a Cessna 150 which can only do about 100Kts it would not be an impossible case although I don't advocate for flying if the ground speed of the wind is over 100kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He also did not ever really &quot;land&quot; (even though the mains touched down) he executed a &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Go-around#Safety&quot; rel=&quot;nofollow noreferrer&quot;&gt;go around&lt;/a&gt;&quot;. As long as sufficient runway and airspeed exists when the mains touched down, applying full throttle is more than safe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation you should never really do something so you can &lt;em&gt;&quot;see what happens&quot;&lt;/em&gt; you should always strive to know what will happen as a result of your actions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can provide the airport (so we can know the runway directions) and the wind reports for that day we will better be able to explain what happened. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-01-13T19:38:52.397" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24333" PostTypeId="2" ParentId="24331" CreationDate="2016-01-13T19:51:59.973" Score="2" Body="&lt;p&gt;You can &lt;a href=&quot;http://www.737ng.co.uk/A320%20321%20FCTM%20Flight%20Crew%20Training%20Manual.pdf&quot; rel=&quot;nofollow&quot;&gt;take a look here&lt;/a&gt; to get a nice idea of some of the published ones (Im sure there are more, I'm still looking for a link to them). In general check lists exist for cases the manufactures may anticipate or unfortunately may have encountered in testing or operation. Some checklists may also stem from sub makers who built individual components like the engines or flight systems.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-01-13T19:51:59.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24337" PostTypeId="2" ParentId="24242" CreationDate="2016-01-14T06:00:14.663" Score="0" Body="&lt;p&gt;I'm adding another answer which looks way too simplistic but I cannot spot why it is wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here goes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term we want to maximize is &quot;smallest height loss for a given azimuth change&quot; &amp;amp; this can be shown to be the following borrowing @PeterKampfs logic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ \frac{\omega}{v_z}=\frac{1}{R * sin \phi}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\phi$ is the glide angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since glide angle is known you must minimize $R$ to maximize the term &quot;smallest height loss for a given azimuth change&quot;. But $$R=\frac{v^2}{g*tan \theta}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to minimize R maximize $tan \theta$ &amp;amp; hence maximize $\theta$. So I might recommend bank as much as you can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there's an additional constraint introduced by the fact that you must not stall (obviously). You must use maximum $\theta$ but not above $\theta_{stall}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let the un-banked stall speed be $v_{stall}$. Under a banked turn of $\theta$ the stall speed increases to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_{stall}^{banked}=v_{stall}*\sqrt{n}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $n$ is the load factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$n=\frac{L}{mg}=\frac{1}{cos \theta}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore in a banked turn of $\theta$ the stall velocity will be:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_{stall}^{banked}=\frac{v_{stall}}{\sqrt{cos \theta}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence the max angle of bank would be the one you should use and that will be:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\theta=arccos \left( \left(\frac{v_{stall}}{v}\right)^2 \right) $$&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2016-01-14T06:40:11.880" LastActivityDate="2016-01-14T06:40:11.880" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24338" PostTypeId="2" ParentId="24267" CreationDate="2016-01-14T07:18:26.503" Score="6" Body="&lt;p&gt;Coded RAREPs (Radar Weather Reports) and SDs (Storm Detections) may still be used to exchange data between radar stations, but for human users they seem to have been superseded by visual displays that provide a more human-friendly visualization of the same information, such as at &lt;a href=&quot;http://www.aviationweather.gov/radar&quot;&gt;http://www.aviationweather.gov/radar&lt;/a&gt;.  The PHAK you linked to (published in 2008) is likely out of date on this.  (But this is the most recent PHAK available.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://weatherjackwilliams.com/answers-weather-radar/&quot;&gt;http://weatherjackwilliams.com/answers-weather-radar/&lt;/a&gt; :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NWS Aviation Weather Center (AWC) doesn’t have any links to the&#xA;  coded SD/ROB reports, but does link to the Radar Summary chart, which&#xA;  is complied from these  reports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This information is also incorporated into a standard weather briefing for a particular flight plan.  The DUAT system used to provide an &quot;SD (Radar Weather Reports)&quot; section in its briefings, but DUAT is no longer available.  &lt;a href=&quot;http://duats.com&quot;&gt;DUATS&lt;/a&gt; instead has a section titled &quot;Radar Summaries&quot; in its briefings.&lt;/p&gt;&#xA;" OwnerUserId="12852" LastEditorUserId="19" LastEditDate="2016-01-14T10:44:59.633" LastActivityDate="2016-01-14T10:44:59.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24339" PostTypeId="1" AcceptedAnswerId="24340" CreationDate="2016-01-14T10:58:52.273" Score="0" ViewCount="548" Body="&lt;p&gt;What does &quot;ENG 2 REV PRESSURIZED&quot; ECAM message mean in the A32F (Airbus A320 Freighter)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the possible consequences and actions the crew should take, on ground and during the flight?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="11665" LastEditDate="2016-01-14T15:13:13.537" LastActivityDate="2016-01-14T16:31:48.367" Title="What does &quot;ENG 2 REV PRESSURIZED&quot; ECAM message mean in the Airbus A32F?" Tags="&lt;jet-engine&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24340" PostTypeId="2" ParentId="24339" CreationDate="2016-01-14T13:12:19.877" Score="3" Body="&lt;p&gt;In case of Airbus A320 (A318/319/320/321) models, ENG 2 REV PRESSURIZED means that the thrust reverser system is pressurized. From FCOM:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;ENG 1(2) REV PRESSURIZED&lt;/p&gt;&#xA;&lt;p&gt;Reverser system is pressurized, while rev doors are stowed and locked with no deploy order.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The crew are expected to reduce the engine thrust to idle when possible in flight (also on ground).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Reverse thrust system is pressurized with reverser doors stowed and locked.&lt;/p&gt;&#xA;&lt;p&gt;THR LEVER 1 (2) .................................. IDLE&lt;/p&gt;&#xA;&lt;p&gt;lf flight conditions permit, reduce the thrust of the affected engine to IDLE as a precautionary measure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;You can see a case where &lt;a href=&quot;http://avherald.com/h?article=4925087b&quot; rel=&quot;nofollow noreferrer&quot;&gt;this warning came on&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Deployment of thrust reversers in flight could have fatal consequences as seen in a B767 &lt;a href=&quot;https://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lauda Air Flight 004&lt;/a&gt; (note that the warning is about reverser pressurization, not deployment).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-14T13:12:19.877" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24341" PostTypeId="1" CreationDate="2016-01-14T14:40:34.117" Score="13" ViewCount="1328" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0zxNo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0zxNo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;I stumbled across a cockpit canopy in the woods. What type of markings should I be looking for to identify this? And where exactly should I be looking for markings to identify this piece? Here is a photo of what I found.&lt;a href=&quot;https://i.stack.imgur.com/amvpM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/amvpM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12995" LastEditorUserId="19" LastEditDate="2016-06-22T11:49:57.073" LastActivityDate="2017-04-12T21:50:18.880" Title="Can you identify this old cockpit canopy?" Tags="&lt;cockpit&gt;&lt;aircraft-identification&gt;" AnswerCount="2" CommentCount="18" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24342" PostTypeId="2" ParentId="24328" CreationDate="2016-01-14T15:04:08.730" Score="18" Body="&lt;p&gt;Based on the provide date, I looked up weather history and the METAR (weather report for pilots) was:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;CYUL 110700Z 24033G49KT 15SM -SHSN OVC033 M02/M08 A2937 RMK SC8 SLP948&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Which translates, in English, to:&lt;/p&gt;&#xA;&lt;p&gt;CYUL weather report at 11th day of the month, 0700 UTC time: Winds at 240 degrees at 33 knots gusting to 49 knots, visibility 15 statue miles, little snow, overcast clouds at 3300 feet, temperature -2C, dew point -8C, altimeter 29.37 inches of mercury; Remarks: scattered clouds at 800 feet, sea level pressure 948 milibars&lt;/p&gt;&#xA;&lt;p&gt;49 knots would be equivalent to 90 km/h, but it is possible that the wind report by the ATC tower was higher at the time of landing.&lt;/p&gt;&#xA;&lt;h2&gt;How much crosswind was there?&lt;/h2&gt;&#xA;&lt;p&gt;Assuming the pilots attempt to land at 24L / 24R, there would be little or no crosswind. However the high wind speed + high &lt;em&gt;&lt;strong&gt;variation&lt;/strong&gt;&lt;/em&gt; of wind speed would be a problem: the fluctuation is 16 knots. For a small airliner like a A321, 16 knots of airspeed gain / loss is a lot. The pilot did not feel comfortable putting it down, so he chose to divert. The decision was a wise one: he tried enough (2 attempts) and concluded he'd better get back while there is still fuel left.&lt;/p&gt;&#xA;&lt;p&gt;(Side story: I once heard a GA pilot who go-around 9 times on the same runway because of high wind. On his 10th approach he crashed)&lt;/p&gt;&#xA;&lt;h2&gt;Was it wise to takeoff?&lt;/h2&gt;&#xA;&lt;p&gt;Yes. Scrolling back the clock a few hours to the time when the pilots would prepare their flight, the weather forecast was:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(...) FM110400 24030G40KT P6SM BKN025 OVC050 (...)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Which translates to: from 0400 UTC time onwards, wind would be 240 degrees at 30 knots gusting to 40. Well, not good, but this was 9 knots below the reported gust when they actually arrived. Moreover, an alternate airport which was within reach and with better winds was chosen. This flight was short, and it is not surprising that on such short flights the alternate is return to the departure airport.&lt;/p&gt;&#xA;&lt;h2&gt;Was it wise to abort the landing and apply full power?&lt;/h2&gt;&#xA;&lt;p&gt;Absolutely! Forcing the plane onto the runway is the exact opposite of what a pilot should do. I will tell you, most (I don't have a number, but a fair guess would be &amp;gt;80%) of the landing accidents occur because the pilots failed to recognize that the aircraft was not fully prepared for landing (gusting winds, too high on approach, flaps not configured etc.). If those pilots chose to apply full power, go around and give it another shot, many lives would have been saved. Many people perceive aborting a landing as &amp;quot;dangerous&amp;quot;; in fact, it's the best thing to do in those situations.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-14T15:11:52.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24344" PostTypeId="2" ParentId="24341" CreationDate="2016-01-14T18:31:48.390" Score="20" Body="&lt;p&gt;Looks like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-47_Stratojet&quot; rel=&quot;noreferrer&quot;&gt;B-47 Stratojet&lt;/a&gt; to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MBSki.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MBSki.jpg&quot; alt=&quot;B-47 canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from wattflyer.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about this particular model. But usually the canopy will have part number markings on it, which can be correlated to the program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see the &lt;a href=&quot;http://b-47.com/?page_id=795&quot; rel=&quot;noreferrer&quot;&gt;B-47 Stratojet association's page&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-14T18:31:48.390" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24345" PostTypeId="1" AcceptedAnswerId="24355" CreationDate="2016-01-14T20:54:40.940" Score="10" ViewCount="694" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/q/1971/8730&quot;&gt;This question&lt;/a&gt; there is discussion about how to determine when to start the descent from cruise. There are several factors at play and it is usually calculated for maximum fuel performance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would this calculation not be done ahead of time, especially for aircraft cruising in class A airspace (presumably by dispatch for part 121 ops)? Why is this not included in the filed flight plan? Wouldn't ATC want to know when to expect this, especially if you lose coms?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-01-15T14:18:56.610" Title="Why isn't the point you begin descent part of the flight plan?" Tags="&lt;air-traffic-control&gt;&lt;flight-planning&gt;&lt;descent&gt;&lt;flight-plans&gt;&lt;dispatch&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24346" PostTypeId="2" ParentId="17672" CreationDate="2016-01-14T21:10:36.443" Score="22" Body="&lt;p&gt;In essence, you are correct.&lt;br&gt;&#xA;It was a conscious decision to do it that way:&#xA;- when the nose pitches up, you're &quot;pitching&quot; toward the slower airspeed on the tape...&#xA;- and you're pitching toward the higher altitude on the altitude tape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question:  why do most aircraft have the higher speed near the top of the tape?  Is it &quot;just because the altitude tape does it that way&quot;?  Or is there a better reason.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having flown the U-2 with the glass cockpit for over 10 years, it is intuitive and is &quot;normal&quot; for me to see that.  &lt;/p&gt;&#xA;" OwnerUserId="12999" LastActivityDate="2016-01-14T21:10:36.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24347" PostTypeId="2" ParentId="24345" CreationDate="2016-01-14T22:17:05.310" Score="8" Body="&lt;p&gt;Because the Top of Descent (TOD) is calculated in flight based on current weather data, STAR/Transition assigned, directs received during the cruise portion of the flight, vectors received taking you off your planned route, etc.. The FMC does the calculation for you with higher precision in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For regular ops, ATC can use the rule of thumb 10.000ft / 30 NM to calculate an estimated TOD. In most cases, they will not need to do that however, as they can give instructions to aircraft to plan a certain STAR entry gate at an assigned flightlevel/altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;R: DLH123, when ready descend FL240 to be level\to reach at ARPEG&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During lost comms, you are expected to maintain your filed or last assigned flightlevel/altitude until you reach the clearance limit. From there you will begin your lost comms procedures which usually include holding at the Initial Approach Fix (IAF), descending at the IAF to the approach altitude, and commending the standard approach procedure for the active runway.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2016-01-14T22:17:05.310" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24348" PostTypeId="1" AcceptedAnswerId="24350" CreationDate="2016-01-14T22:39:56.997" Score="8" ViewCount="3923" Body="&lt;p&gt;In &lt;a href=&quot;https://skyvector.com/?ll=34.1528730618389,-118.67356454272175&amp;amp;chart=114&amp;amp;zoom=2&quot; rel=&quot;nofollow&quot;&gt;Los Angeles TAC&lt;/a&gt; you'll see magenta boxes with SOCAL frequency and other information. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was just wondering what is 20NM reference point is? in other word, 20NM from where or what? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="43" LastEditDate="2016-03-04T21:59:41.233" LastActivityDate="2016-10-16T14:26:38.430" Title="What is 20NM reference point in &quot;CTC SOCAL WITHIN 20NM&quot;?" Tags="&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24349" PostTypeId="2" ParentId="24348" CreationDate="2016-01-14T22:53:13.697" Score="2" Body="&lt;p&gt;On this TAC the 20NM is not really in reference to any particular point as much as it is in reference to the &quot;Primary Airspace&quot; (really class B or C, which is usually referenced around an airport). So if you are within 20NM of the center (main airport) of any primary airspace, this is the frequency you could contact for flight following or to transition through the airspace. In this case, thats LAX, VNY, BUR, SNA, ONT, RIV. Boxes outlined in blue are the frequencies for entering the class B while the magenta boxes are the frequencies to contact to enter the class C (see pic below from the TAC). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QCEMS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QCEMS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are not mandatory contact instructions outside of the airspace (although you should always check local procedures). The standard radio contact procedures apply in the given airspaces. These are printed so you don't need to pull out your AFD to look up frequencies. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-14T23:05:19.473" LastActivityDate="2016-01-14T23:05:19.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24350" PostTypeId="2" ParentId="24348" CreationDate="2016-01-14T23:25:15.793" Score="8" Body="&lt;h2&gt;&lt;strong&gt;Short answer:&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The primary Class C airport&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;Longer Answer:&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Your question refers to the magenta boxes on sectional and TAC charts that read &lt;code&gt;CTC SOCAL APP WITHIN 20 NM on 134.2 338.2&lt;/code&gt;, or equivalent:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5BOQX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5BOQX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These boxes are used in connection with the nearest Class C airspace on the chart. Arriving pilots are requested to contact approach within 20 NM of &lt;em&gt;the primary Class C airport&lt;/em&gt;. This is the answer to your question, the primary airport of that Class C airspace. Which airspace and airport exactly will depend on which magenta boxes you look at on the Los Angeles TAC. In the chart examples above and below, that airport would be Bob Hope (KBUR).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deeper significance behind this instruction is the procedural Outer Area of the Class C airspace which is not depicted on the charts. Though not mandatory, this outer area of the Class C airspace is still considered part of the controlled airspace, and pilots are asked to contact approach before entering this area. See section 3-2-4 of the &lt;a href=&quot;https://www.gleim.com/aviation/faraim/?leafNum=1d6c506a&amp;amp;terms[]=intercept#avTab%3DleafNum%3D1d6c506a&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Manual (AIM)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3-2-4 c. 2. (b)&lt;br&gt;&#xA;  NOTE-&lt;br&gt;&#xA;  4. Though not requiring regulatory action, Class C airspace areas have a &#xA;  procedural Outer Area. Normally this area is 20 NM from the primary&#xA;  Class C airspace airport. Its vertical limit extends from the lower&#xA;  limits of radio/radar coverage up to the ceiling of the approach&#xA;  control's delegated airspace, excluding the Class C airspace itself,&#xA;  and other airspace as appropriate. (This outer area is not charted.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the locations of the boxes on the chart (see image below) roughly correspond to the various approach sectors, with the frequencies contained in the boxes varying accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that the blue boxes similarly correspond to Class B airspace, though the 20 NM note is absent, since Class B does not have the unmarked Procedural Area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FD7Zs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FD7Zs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-10-16T14:26:38.430" LastActivityDate="2016-10-16T14:26:38.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24351" PostTypeId="1" AcceptedAnswerId="24363" CreationDate="2016-01-15T02:05:58.937" Score="2" ViewCount="612" Body="&lt;p&gt;Each JT8D engine on a 727 has two tachometer generators as part of the engine tachometer system to measure N1 and N2 speeds. Are these generators line replaceable units? How long would replacement of just one generator take?&lt;/p&gt;&#xA;" OwnerUserId="12666" LastActivityDate="2016-01-15T11:17:16.693" Title="Are the N1 and N2 tachometer generators installed on 727 / JT8D engines line replaceable units?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24352" PostTypeId="1" AcceptedAnswerId="24353" CreationDate="2016-01-15T02:59:16.553" Score="25" ViewCount="4357" Body="&lt;p&gt;Via &lt;a href=&quot;http://www.rapp.org/archives/2015/11/tragic/&quot;&gt;this post by Ron Rapp&lt;/a&gt;, I found &lt;a href=&quot;https://youtu.be/9zLO5Sem6Ew&quot;&gt;this video&lt;/a&gt; of a plane owner and builder dismantling a GA plane and then scrapping the airframe. The video claims this is because&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;after consulting with aviation attorneys and other experts regarding builder's liability, the owner concluded there was only one way out.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, I'm completely in the dark about - and rather baffled by - what this liability risk would be, and how it relates to the &lt;a href=&quot;http://www.aviationlawmonitor.com/2015/10/articles/general-aviation/vans-aircraft-company-sued/&quot;&gt;Van's Aircraft lawsuit&lt;/a&gt;. What liability would a builder pilot be under in the event of a crash that they would be able to avoid if the plane were factory-produced?&lt;/p&gt;&#xA;" OwnerUserId="3233" LastEditorUserId="3233" LastEditDate="2016-01-17T13:57:07.193" LastActivityDate="2016-01-17T13:57:07.193" Title="What liability concerns would drive an airplane homebuilder to scrap their plane?" Tags="&lt;liability&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24353" PostTypeId="2" ParentId="24352" CreationDate="2016-01-15T03:17:08.817" Score="29" Body="&lt;p&gt;I understand that the aircraft owner had sought for some time to donate the aircraft. I would presume that he had come to a time in life where he was, or felt he was, no longer able to fly the aircraft, and so was seeking to rid himself of what may have become a burden (hangar fees, etc.).&lt;/p&gt;&#xA;&lt;p&gt;To quote liberally from the builder/destroyer's daughter who created and uploaded the YouTube video (this is quoted from what she wrote in the video description):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;It took him two years to make this decision about his plane. He did actually try to donate it to a couple of aviation schools in the area and the schools politely refused the offer. He also tried to donate to a local museum and was also refused.&lt;/p&gt;&#xA;&lt;p&gt;He knew when he built the plane he might face this decision one day, but he hoped some of the laws would have changed by that time.&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;Mr. Ron Rapp, author of the article “A Tragic Pile of Twisted Metal” and noted blogger on his website The House of Rapp., highlights many reasons my Dad made this decision among others.&lt;/p&gt;&#xA;&lt;p&gt;A couple months before my dad made his final decision, a local fellow pilot was named in a lawsuit because he sold the plane he built to a man that later crashed and killed himself in the plane. The spouse of the buyer filed the suit and also named other companies who made parts used to build the plane.&lt;/p&gt;&#xA;&lt;p&gt;Many have commented that he should have used a limited liability entity, such as a LLC or a corporation to sell the plane. However, because the plane was not, at the time of manufacturing, owned in a properly capitalized limited liability entity with a legitimate business purpose and was, in fact, used purely for personal reason, courts would in almost all cases “pierce the corporate veil.” Therefore, this does not offer adequate (or any) protection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I don't think I can add a whole lot to that. Apparently, he had decided that he was unwilling to take on the liability of letting someone else fly what he had built. In the absence of a party interested in the aircraft for anything other than flight, he chose to destroy it.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-15T12:05:35.200" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24354" PostTypeId="2" ParentId="24352" CreationDate="2016-01-15T03:34:33.947" Score="26" Body="&lt;p&gt;The USA has a culture of lawsuits, often frivolous.  When airplanes crash, people die and the estates of those people want someone to blame.  In the past they've tried to blame aircraft manufacturers and the resulting lawsuits were detrimental to general aviation.  It got to the point that congress had to step in and shield the industry from lawsuits (see: &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Aviation_Revitalization_Act&quot;&gt;General Aviation Revitalization Act of 1994&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, these protections don't apply to individuals.  Van's aircraft may get sued and if a judgement comes down the company will probably fold and cease to exist.  If you as an individual get slapped with a wrongful death lawsuit and a judgement is found against you, it will ruin you financially.  If you are getting to be old and retired, you may never recover from it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The liability the builder shoulders is the accountability if anything ever goes wrong with the airplane, in perpetuity.  If that plane crashes some day and especially if it is fatal, someone is going see it is a homebuilt experimental and sue the guy who put it together, alleging they did something wrong.  It'll be expensive to lose and nearly as expensive to win (lawyers are not cheap).  &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-15T03:34:33.947" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24355" PostTypeId="2" ParentId="24345" CreationDate="2016-01-15T03:53:27.690" Score="6" Body="&lt;p&gt;You can calculate ToD beforehand or let the FMS do the work.  In reality though, you generally don't get to wait until your optimal ToD to start descending, especially flying into busy airports.  If the airport has arrival routes, you'll be flying one and there will be crossing restrictions that are either part of the arrival clearance or expected clearances from ATC.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are flying the route you'll set the crossing restriction altitudes in the FMS and the FMS will generate ToD points to make those restrictions.  You can also use the 1000' / 3NM rule to calculate your own ToD for each crossing restriction.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going into smaller fields I often set my own target altitude of 10,000' 30 NM from the airport and used that to generate a ToD for descending from cruise.  If you are landing in the direction of your arrival into a small airport and ATC is generous with pilot discretion descents you can sometimes manage an idle descent from cruise all the way to the FAF, but not often.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, while the ToD might not explicitly be on the flight plan, it is accounted for in the planning.  The dispatcher has to account for expected fuel burn for the flight so we have the right amount of fuel, and the performance calculations they do takes the descent from cruise into the terminal environment into account.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2016-01-15T14:18:56.610" LastActivityDate="2016-01-15T14:18:56.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24356" PostTypeId="1" CreationDate="2016-01-15T08:29:10.507" Score="6" ViewCount="588" Body="&lt;p&gt;&lt;strong&gt;Full-Scale 1903 Wright Flyer failed the test Thrust = Drag in a NASA wind tunnel&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have found a presentation about an extensive set of tests done in 1999 on a full scale replica of Flyer I 1903. The plane did not behave well and was not able to produce enough thrust to overcome the drag. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;em&gt;In the wind tunnel, the reproduced propeller fell short of T=D @ 28 mph test condition when operating at the maximum permitted speed of 340 RPM. These data are being analyzed&lt;/em&gt;&quot;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Tv5IQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tv5IQ.png&quot; alt=&quot;$C_L=C_L(C_D)$&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;$C_L=C_L(C_D)$ Flyer I replica&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://instructional1.calstatela.edu/cwu/me403/Supplementary/WrightTest.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Full-Scale 1903 Wright Flyer Wind Tunnel Test Results From the NASA Ames Research Center&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the presentation, also quite explicit, does not give the values of the Thrust, Drag or Drag - Thrust at 28 mph. I calculated the Drag from $C_L=C_L(C_D)$, Lift = Weight (the mass of the airplane is known) and and the surface of the wings. Using a simulator I also evaluated the thrust delivered by some modern propellers, having the same diameter as the ones the Wright Brothers said they had used in 1903, and they deliver enough thrust at 28 mph and 340 RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There should be other more detailed articles, which I can not find, about the same set of tests because they planned the experiments for years and it is expected a lot of data was obtained. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I would be really interested to know either the exact geometry of the propellers&lt;/strong&gt; to calculate their thrust with a simulator or find somewhere the diagram $Thrust &#xA;= Thrust_{340\:RPM}(v_{air})$ corresponding to the tested replica. &lt;strong&gt;If you can find such a document please tell me about it.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway at 6 hp / propeller (12 hp in total) I calculated that only propellers with an efficiency well below 50% (miserable even for the standard of 1903) could have failed to produce enough thrust for the Flyer I replica at 28 mph.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 1&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Mathcad demonstration which shows that the efficiency of the propellers used by the Flyer I replica should be below 31.2% to fail the test T = D.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PceVw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PceVw.png&quot; alt=&quot;A Mathcad demonstration which shows that the efficiency of the propellers used by the Flyer I replica should be below 31.2% to fail the test T = D&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Update 2&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another wind tunnel set of tests was done in 2003 on a different Flyer I replica (see: &lt;a href=&quot;http://www.wrightexperience.com/edu/12_17_03/pdfs/1903_paper.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flying Qualities of the Wright 1903 Flyer:&#xA;From Simulation to Flight Test&lt;/a&gt;). Also the lift drag diagram for the case &quot;props off&quot; was about the same as the one obtained in 1999, the thrust generated by the propellers at 340 RPM and Q = 2 psf which translates in a 28 mph plane speed, the same as in the 1999 tests, was 80 lbf (36.28 kgf) more than double than the Drag = 17.44 kgf calculated for the 1999 replica. Unless quite different propellers had been used in 1999 and 2003 the 1999 propellers should not have failed the test T = D at 28 mph. It appears that various investigation teams have used propellers with different geometries. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9XbSK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9XbSK.png&quot; alt=&quot;Flyer I 2003 replica - Drag Coefficient, On Rail &quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Flyer I 2003 replica - Drag Coefficient, On Rail - Propellers off&lt;/em&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/jg7Uj.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jg7Uj.png&quot; alt=&quot;Flyer I 2003 - Thrust&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Flyer I 2003 replica - Static and dynamic thrust of the propellers two dynamic pressures, $Q = 0.5\rho V^2$. 1) $Q = 1\:lbf/ft^2$ ($V=19.98\:mph$) 2) $Q = 2\:lbf/ft^2$ ($V=28.26\:mph$). $\rho=1.2\:kg/m^3$&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.wrightexperience.com/edu/12_17_03/pdfs/1903_paper.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Flying Qualities of the Wright 1903 Flyer:&#xA;From Simulation to Flight Test&quot; (AIAA-2004-0105)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2016-01-16T21:48:37.443" LastActivityDate="2016-01-16T21:48:37.443" Title="What was the exact propeller geometry of the 1903 Wright Flyer? A modern replica failed the test T = D in a NASA wind tunnel" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2016-01-21T12:00:00.993" ContentLicense="CC BY-SA 3.0" />
  <row Id="24357" PostTypeId="1" CreationDate="2016-01-15T08:51:02.330" Score="5" ViewCount="2142" Body="&lt;p&gt;A number of drones these days like the one shown in the picture below have  fully protected &lt;strong&gt;&lt;em&gt;multi-rotor propeller guard&lt;/em&gt;&lt;/strong&gt; system . These are lightweight, aerodynamic housing that keeps these spinning knife-blades away from people's fingers, trees etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So,what are the  physical/aerodynamic implications of designing a prop guard for a multirotor drone whose specs are as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;All Up Weight with battery: 1050g&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Frame weight empty (no electronics, motors, or battery): 400g&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flight time with 3s 2200mah lipo: 8 minutes&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Propeller size : 10&quot;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Skeletal Plastic Structure&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1BA5z.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1BA5z.png&quot; alt=&quot;Prop Guards for multirotors&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Source: Safe Flight Copters&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="9142" LastActivityDate="2016-01-15T16:25:28.433" Title="What are the physical/aerodynamic implications of designing a prop guard for multirotors?" Tags="&lt;aerodynamics&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24358" PostTypeId="1" CreationDate="2016-01-15T09:33:25.630" Score="9" ViewCount="8077" Body="&lt;p&gt;Why are PAPI lights installed 300m from the threshold?&#xA;What are the conditions that define the position of the PAPI lights from threshold?&lt;/p&gt;&#xA;" OwnerUserId="13003" LastEditorUserId="167" LastEditDate="2016-01-16T16:47:53.133" LastActivityDate="2017-10-23T04:51:54.610" Title="What determines the positioning of PAPI lights from the runway threshold?" Tags="&lt;approach&gt;&lt;airport-lighting&gt;&lt;papi&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24359" PostTypeId="2" ParentId="24358" CreationDate="2016-01-15T09:53:18.487" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uFVTA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uFVTA.jpg&quot; alt=&quot;PAPI Jersey&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Precision_approach_path_indicator#/media/File:PAPI_Jersey_Airport.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;WikiPedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this picture, you see that the PAPI is placed right next or near to the &lt;a href=&quot;https://aviation.stackexchange.com/a/16743/572&quot;&gt;touchdown zone&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wmla0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wmla0.png&quot; alt=&quot;ToucdownZone&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Image Source: &lt;a href=&quot;https://aviation.stackexchange.com/q/16714/572&quot;&gt;Aviation.SE&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you want guidance for this area, placing them near the threshold would actually make you aim too close to the threshold and increase the possibility of touching down too short of the runway.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-01-15T09:53:18.487" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24360" PostTypeId="2" ParentId="24357" CreationDate="2016-01-15T09:56:45.060" Score="3" Body="&lt;p&gt;Aerodynamically, one can say that those prop guards create some kind of Fenestron (Like some tail rotors in helicopters), which will reduce the tip losses of the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, they will increase drag in forward flight, reducing the UAV top horizontal speed. If you take a look at the Aibotix X6 you see a one piece prop guard designed aerodynamically to reduce drag in forward flight.&#xA;In the particular case of your image, the black web also decreases the area of air flow into the propeller, certainly reducing its efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another prop guards disadvantage is the weight they add. Even though they might be made of lightweight material, they have to have some strength to resist any impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sum up, with a prop guards like those, you should loose top speed and around 2 minutes of flight time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last tip: if you want to fly your UAV close to trees, forests or power lines, be careful with the prop guards because you might end with your UAV hanging on a tree branch 10m high... (happened to me :/)&lt;/p&gt;&#xA;" OwnerUserId="11121" LastActivityDate="2016-01-15T09:56:45.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24361" PostTypeId="2" ParentId="21368" CreationDate="2016-01-15T10:22:35.023" Score="2" Body="&lt;p&gt;In europe the MRO are regulated by Part 145, this part precise that you have to be  Certifying staff (owner of part 66) to work on aircraft. &#xA;For all other people you can't even loose a bolt except if you are under supervision of qualified Certifying staff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For engineering work (without work on aircraft) you only need to have a sufficient degree (under company appreciation except for special works like airworthiness where this in precised in concerned regulation (Part M for example)).&lt;/p&gt;&#xA;" OwnerUserId="3039" LastActivityDate="2016-01-15T10:22:35.023" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24362" PostTypeId="2" ParentId="24357" CreationDate="2016-01-15T11:14:18.040" Score="3" Body="&lt;p&gt;In general, having a shroud (a duct actually) over the propeller reduces the tip losses; however, in an UAV, this effect is pretty small (and requires tight clearances) in order to have any practical effect. Also, if the ducts are not designed properly, the flow entering the propellers may be affected, reducing the performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main disadvantage is the weight- the shroud and the support structure will affect the performance adversely (also, there is some increased drag) and is usually not recommended. For an UAV having endurance of mere minutes, the effects can be substantial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main advantage is safety- the propellers are safe from hitting the ground and getting damaged; so if you are reasonably confident of your flying abilities it is better to go without a shroud, rather than with one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is that the addition of aftermarket shrouds to UAVs have to be evaluated carefully- the weight may alter the flying properties appreciably (for e.g. the descent rate), so one has to be careful.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-15T11:14:18.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24363" PostTypeId="2" ParentId="24351" CreationDate="2016-01-15T11:17:16.693" Score="3" Body="&lt;p&gt;Usually, they are. In case of the JT8D engine, the N1 tach generator (inside the nose bullet), atleast is a LRU. The AMT Society even has a &lt;a href=&quot;http://www.amtsociety.org/pdf/MSC09-Handbook.pdf&quot; rel=&quot;nofollow&quot;&gt;competition which involves the removal of N1 tacho generator&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-15T11:17:16.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24364" PostTypeId="2" ParentId="24358" CreationDate="2016-01-15T13:24:45.110" Score="12" Body="&lt;p&gt;US DoT &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwj07LLp2avKAhUT1I4KHRzmBkEQFggbMAA&amp;amp;url=http%3A%2F%2Fwww.faa.gov%2FdocumentLibrary%2Fmedia%2FOrder%2FFINAL%2520FAA%2520Order%25206850.2B.pdf&amp;amp;usg=AFQjCNEnRPLqc3o7UOLX4FpYaL7Khdngxg&amp;amp;bvm=bv.112064104,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;Order JO 6850.2B&lt;/a&gt; contains installation criteria for visual guidance lighting systems. The following is taken from that order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For siting PAPI along the runway, in case an (ILS) electronic glide slope is present, the lights are located such that the PAPI visual approach path coincides with the one produced electronically as much as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of runways without an electronic glide slope, the following criteria are considered for locating the PAPI:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Threshold Crossing Height&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The TCH is the height of the lowest on-course signal at a point directly above the intersection of the runway centerline and the threshold. The minimum allowable TCH varies according to the height group of aircraft that use the runway, ... The PAPI approach path must provide the proper TCH for the most&#xA;  demanding height group that uses the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Glide Path Angle&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The visual glide path angle is the center of the on-course zone, and shall normally be 3 degrees when measured from the horizontal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstacle Clearance Surface&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The PAPI obstacle clearance surface is established to provide the pilot with a minimum clearance over obstacles during approach. The PAPI must be positioned and aimed so that no obstacles penetrate this surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8v7NW.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8v7NW.png&quot; alt=&quot;PAPI&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from US DoT JO 6850.2B Visual Guidance Lighting Systems&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, in case ILS is there, align the PAPI with that; else locate the PAPI such that it satisfies TCH and OCS.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-15T13:24:45.110" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24365" PostTypeId="1" AcceptedAnswerId="24368" CreationDate="2016-01-15T16:17:30.190" Score="8" ViewCount="1550" Body="&lt;p&gt;I understand that 100% Isopropyl Alcohol (IPA) is used as a Fuel System Icing Inhibitor (FSII) additive in aviation gasoline systems—including 87 through 100LL fuel types—for cold weather operations. I know that IPA is, or can be, included as part of AvGas formulation. However, I am referring to operational use of IPA as an additive when fueling the aircraft. Pure IPA is also known as anhydrous isopropanol.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What documentation is available to support such use?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What is a proper treatment ratio for using IPA as an FSII (or what is the concentration limit)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-15T16:54:18.670" LastActivityDate="2019-08-29T13:41:44.010" Title="How should Isopropyl Alcohol be used as an AvGas Fuel System Icing Inhibitor?" Tags="&lt;fuel&gt;&lt;refueling&gt;&lt;cold-weather&gt;&lt;avgas&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24366" PostTypeId="2" ParentId="24357" CreationDate="2016-01-15T16:25:28.433" Score="3" Body="&lt;p&gt;Remember the drag contribution of a biplane's bracing wires? Now this quadcopter has not one, but two screens in the flow path of the propellers. Each thread of the mesh will act like a small bracing wire and reduce propeller efficiency considerably.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In comparison, the shroud has relatively little impact. Tip clearances are too big and shroud size is too small to improve propeller efficiency measurably, the drag in forward flight should be manageable and the worst contribution of the shrouds is probably their added mass. But it all pales in comparison to those two layers of mesh!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-15T16:25:28.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24367" PostTypeId="2" ParentId="24365" CreationDate="2016-01-15T16:28:27.000" Score="3" Body="&lt;p&gt;It seems as though there was an accident involving a PA-23-180 a while back that lead to this advisory. You can see &lt;a href=&quot;http://www.ntsb.gov/safety/safety-recs/recletters/A85_77_80.pdf&quot; rel=&quot;nofollow&quot;&gt;the full report here&lt;/a&gt; (interestingly this was published by the NTSB not the FAA). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Require that Piper, Beech, and other airplane manufacturers who have&#xA;  not already done so issue service and operating information regarding&#xA;  the use of fuel additives in piston-powered airplanes for cold weather&#xA;  operation and incorporate this information in the pilot operating&#xA;  handbooks of all newly manufactured airplanes. (Class 11, Priority&#xA;  Action) (A-85-79)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In terms of limits it looks like it might be in the POH and should be in the AFM for the aircraft or in a service bulletin like this one issued for &lt;a href=&quot;http://www.mdhelicopters.com/publications/pdf/900storage/service_bulletins/sb900050.pdf&quot; rel=&quot;nofollow&quot;&gt;MD helicopters&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://bvfs.net/uploads/files/N212BS_POH.pdf&quot; rel=&quot;nofollow&quot;&gt;AFM for this 172S&lt;/a&gt; (page 4-23) notes the use of IPA and redirects to section 8 (page 8-17) which says a 1% by volume quantity should be used. It also offers some steps on how to add it to the fuel and a nice chart on volume of additive vs volume of fuel. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="12720" LastEditDate="2016-01-15T17:27:49.267" LastActivityDate="2016-01-15T17:27:49.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24368" PostTypeId="2" ParentId="24365" CreationDate="2016-01-15T17:03:45.997" Score="5" Body="&lt;p&gt;FAA Advisory Circular &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22282&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC No: 23.1521-1B&lt;/a&gt; deals with use of IPA for Part 23 aircraft. It states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ASTM D 910, Standard Specification for Aviation Gasolines, allows the use of isopropyl alcohol conforming to the requirements of ASTM D 4171, specifications for Fuel System Icing Inhibitor, as a fuel system icing inhibitor. Accordingly, isopropyl alcohol conforming to ASTM D 4171 may be used in concentrations up to 1 percent by volume, to benefit safety, as an icing inhibitor in automobile gasoline.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, it is left to the aircraft manufacturers (according to ASTM 910 too) to determine whether or not to use IPA as an additive. For example, in a letter regarding Lycoming engines in certain of their aircraft, &lt;a href=&quot;http://www.ttt-aviation.com/Cessna-letter.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna says&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Isopropyl alcohol in amounts not to exceed 1% by volume can be added only to aviation fuel  (not  automotive  fuel)  to  prevent  ice  formation  in  fuel  lines  and  tanks.  Although approved  for  use  in  Lycoming  engines,  do  not  use  isopropyl  alcohol  in  the  aircraft  fuel systems unless approved by the aircraft manufacturer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that Cessna allows the addition of IPA only to aviation fuel for the applicable aircraft. In UK, the &lt;a href=&quot;http://www.pertamina.com/aviation/files/avgas-spec.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;MoD Defense Standard 91-90&lt;/a&gt; again leaves the matter to the individual manufacturers, saying,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The concentration of Isopropyl Alcohol shall be recommended by the aircraft&#xA;  manufacturer at the time of delivery to the purchaser and typically not exceeding 1% v/v.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Though almost all these cap the IPA at 1%, the best way is to refer to the individual aircraft's appropriate manual as it would have the necessary details. But generally, I think that manufacturers (of large aircraft, atleast) prefer not using IPA these days due to environmental concerns.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3825" LastEditDate="2017-05-15T19:47:21.603" LastActivityDate="2017-05-15T19:47:21.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24369" PostTypeId="1" AcceptedAnswerId="24371" CreationDate="2016-01-15T20:49:23.187" Score="10" ViewCount="357" Body="&lt;p&gt;I'm working on getting my PPL, and I would like to read more about the specific causes of small private aircraft (single or twin prop, primarily) crashing, especially those that were caused by pilot error. Are there any good books or other resources on this matter? A decent amount of searching hasn't turned up much -- it seems like the data from private charter jets is often combined with that of the aircraft I'm interested in.&lt;/p&gt;&#xA;" OwnerUserId="12946" LastEditorUserId="19" LastEditDate="2016-06-22T11:50:37.967" LastActivityDate="2016-06-22T11:50:37.967" Title="What are good resources on causes of private aircraft crashes?" Tags="&lt;safety&gt;&lt;accidents&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24370" PostTypeId="2" ParentId="24369" CreationDate="2016-01-15T21:42:52.850" Score="1" Body="&lt;p&gt;The National Transportation Safety Board investigates vehicle-related accidents in the United States and publishes &quot;accident reports&quot; which includes details of the accidents and the findings of the investigators. &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Pages/aviation.aspx&quot; rel=&quot;nofollow&quot;&gt;Go nuts.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="3825" LastEditDate="2016-01-16T01:57:37.607" LastActivityDate="2016-01-16T01:57:37.607" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24371" PostTypeId="2" ParentId="24369" CreationDate="2016-01-15T22:23:37.503" Score="7" Body="&lt;p&gt;The AOPA's &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Air-Safety-Institute&quot;&gt;Air Safety Institute&lt;/a&gt; has quite a few resources that I like to review from time to time, including some great videos with commentary on exceptional cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Accident-Analysis&quot;&gt;AOPA ASI Accident Analysis Page&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.aopa.org/Education/Accident-Case-Studies&quot;&gt;AOPA Accident Case Studies&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://www.aopa.org/Education/Real-Pilot-Stories&quot;&gt;AOPA Real Pilot Stories&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do exactly what you are doing, during training and still after, but I'd like to also say that you shouldn't narrow yourself to GA crashes, a lot of what happens commercially can be applied to GA, and usually with commercial accidents there is a lot more data and analysis available to work with. In that regard, I like to watch shows on Youtube like &lt;a href=&quot;https://www.youtube.com/results?search_query=air+crash+investigation&quot;&gt;&quot;Air Crash Investigation&quot;&lt;/a&gt;, or on TV like &lt;a href=&quot;https://www.youtube.com/results?search_query=why+planes+crash&quot;&gt;&quot;Why Planes Crash&quot; (some available on Youtube)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/asf/ntsb/search_ntsb.cfm&quot;&gt;AOPA also has a lot of resources to view NTSB reports&lt;/a&gt; on individual crashes where you can search by certain criteria like aircraft type, states, type of flight, or even some specific keywords like &quot;Vacuum Failure&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just don't limit yourself to looking at things like &quot;Pilot Error&quot;, pilot error is a broad category of crashes that is usually used to describe the pilot doing something wrong &lt;em&gt;in the air&lt;/em&gt;, but a lot of crashes are &quot;pilot error&quot; in that the pilot could have broke the accident chain much earlier in the flight. Read as many as you can, regardless of the cause. For example an accident where the aircraft breaks up in flight may not be attributed to pilot error, but its good to know what lead to the break up and what could have been prevented.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-01-15T22:32:23.060" LastActivityDate="2016-01-15T22:32:23.060" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24372" PostTypeId="1" CreationDate="2016-01-15T21:28:07.763" Score="1" ViewCount="73" Body="&lt;p&gt;And would it save lives?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This video quotes no sources (except the usual &quot;someone&quot;) but has gone viral:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.facebook.com/ScienceNaturePage/videos/761924050606522/&quot; rel=&quot;nofollow&quot;&gt;https://www.facebook.com/ScienceNaturePage/videos/761924050606522/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="519" OwnerDisplayName="gd1" LastEditorUserId="62" LastEditDate="2016-07-05T15:01:01.403" LastActivityDate="2016-07-05T15:01:01.403" Title="Is a massive parachute coming out from an ejectable fuselage technically possible for a commercial aircraft?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;airframe-parachute&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-01-15T22:38:19.180" ContentLicense="CC BY-SA 3.0" />
  <row Id="24373" PostTypeId="1" AcceptedAnswerId="24419" CreationDate="2016-01-16T00:19:08.140" Score="6" ViewCount="1335" Body="&lt;p&gt;I posted this question on StackOverflow &lt;a href=&quot;https://stackoverflow.com/q/34821674/1735836&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://stackoverflow.com/users/1058607/terriblememory&quot;&gt;terriblememory&lt;/a&gt; suggested I post it here.  I didn't even know there was an aviation stack exchange.  Cool!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have been scowering the internet all day for a third-party weather&#xA;  API that &lt;strong&gt;reports more than just the cloud coverage&lt;/strong&gt; for cloud&#xA;  information.  I need to know the height of the cloud.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;I need something like an aviation weather API that reports either the&#xA;  &lt;strong&gt;cloud height&lt;/strong&gt;, the &lt;strong&gt;cloud max and min vertical position&lt;/strong&gt;, or the &lt;strong&gt;cloud type&lt;/strong&gt; (Cirrus, Stratus, Cumulus, etc.) from which we could then derive the relative height.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;We want the API to be free at least during development.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I found some relative information in this stack exchange and one answer &lt;a href=&quot;https://aviation.stackexchange.com/q/8683/13007&quot;&gt;here&lt;/a&gt; that tells how to find the cloud tops but I'm posting this question anyway in case there is an API yet to be suggested.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, I'll be taking a look at the other information I found in this stack exchange.  Thank you in advance for suggestions.&lt;/p&gt;&#xA;" OwnerUserId="13007" LastEditorUserId="-1" LastEditDate="2017-05-23T12:41:54.650" LastActivityDate="2016-07-14T08:03:18.300" Title="Is there a 3rd-party API for aviation weather forecast, which includes additional cloud information?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24374" PostTypeId="2" ParentId="24373" CreationDate="2016-01-16T03:20:10.523" Score="4" Body="&lt;h2&gt;Short answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I wish this information were available, but what you are looking for is simply not available.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longer answer:&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There has to be something out there else how would pilots know to&#xA;  climb to a destination altitude to get above the clouds?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You are looking for data that you rightly think should exist. I would that it did, but it doesn't. Thats where the &lt;em&gt;art&lt;/em&gt; of airmanship comes in. The answer to your question I quoted above is a complex mix of years of experience reading the weather charts, eyeballing the view out the window, and networking through the radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Real world weather is too hard to predict, and is constantly in flux. The only way to know the actual cloud conditions is to get out there and see it in the moment. The ground based weather observation stations like AWOS and ASOS do a decent job, but they are very limited and often wildly inaccurate. They only provide an assessment what is visible straight up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationweather.gov/airep&quot; rel=&quot;nofollow&quot;&gt;PIREPS&lt;/a&gt; are the only partial answer you will get, and these are sparse and dated. A PIREP is only a snapshot of what a pilot observed at one place at one time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aviationweather.gov/areafcst&quot; rel=&quot;nofollow&quot;&gt;Area forecasts&lt;/a&gt; will sometimes include a cloud top forecast (look for &quot;TOP FL200&quot; or similiar). However, a forecast—especially an area forecast which often covers half a state—is vastly different than an observation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You've already mentioned Skew-T charts, and they do have useful data. Depending on your application, this might end up being your best bet. If you want something that doesn't have a real world aviation application (e.g. for the SIM community), you could derive your sought information from this.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-01-16T03:20:10.523" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24376" PostTypeId="1" AcceptedAnswerId="24377" CreationDate="2016-01-16T03:52:35.933" Score="11" ViewCount="802" Body="&lt;p&gt;I was listening to ATC and I heard the pilot say that they are going to autoland. What is the purpose of providing this info to ATC?&lt;/p&gt;&#xA;" OwnerUserId="12603" LastEditorUserId="19" LastEditDate="2017-06-06T08:52:47.710" LastActivityDate="2017-06-06T08:52:47.710" Title="Why did the pilot inform ATC that he is going to autoland?" Tags="&lt;autoland&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24377" PostTypeId="2" ParentId="24376" CreationDate="2016-01-16T04:24:49.167" Score="9" Body="&lt;p&gt;From what you said, I'm assuming that the pilot had informed that he/she is going to autoland under VMC.&lt;/p&gt;&#xA;&lt;p&gt;The main reason is that the autoland procedure requires accurate guidance and the ILS signals may be disturbed by the traffic (both surface and air). So, the pilots want to inform the ATC that they want undisturbed signal. From a &lt;a href=&quot;http://www.caa.gov.qa/sites/default/files/FOIL%2001_04_use%20of%20Auto%20land.pdf&quot; rel=&quot;noreferrer&quot;&gt;Flight Operations Information leaflet from CAA, Qatar&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Most ILS installations are subject to signal interference by either surface vehicles or aircraft. To prevent this interference ILS critical areas are established near each localiser and glideslope antenna.&lt;/p&gt;&#xA;&lt;p&gt;The ILS sensitive area is protected from all surface vehicles and aircraft when ILS Category II or III operations are conducted or anticipated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;These disturbances may happen when Low Visibility Procedures (LVPs) are not in force and may cause problems for the approaching aircraft:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the LVPs are not in force, ILS beam bends may occur because of vehicle&#xA;or aircraft interference. Sudden and unexpected flight control movements may occur at a very low altitude or during the landing and rollout when the autopilot attempts to follow the beam bends.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Due to these reasons, it is better for the pilots to inform the ATC about their intention to autoland so that appropriate measures can be taken or if it is not possible, the same can be relayed to the approaching aircraft.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The ATC should be informed about the intention to conduct an autoland. Such&#xA;information should not be taken as a request for or expectation of the protection of the ILS but is merely given to enhance the possibility for ATC to inform the flight crew of any known or anticipated disturbance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also, the ATC has to adjust the aircraft spacing if autolands are being conducted, which may affect the operations.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-16T04:24:49.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24378" PostTypeId="1" AcceptedAnswerId="24383" CreationDate="2016-01-16T10:49:56.427" Score="4" ViewCount="674" Body="&lt;p&gt;I believe I am beginning to understand how a leading edge vortex creates lift. Faster air creates a lower pressure above the wing making lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I am hoping to get another view of this in terms of momentum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this vortex draw in air from above, pulling it downward and as a result lifting the plane up? Or is the vortex shed downward off the tail of the wing? How does this work?&lt;/p&gt;&#xA;" OwnerUserId="13013" LastEditorUserId="19" LastEditDate="2017-08-10T09:53:53.047" LastActivityDate="2017-08-10T09:53:53.047" Title="Where does upward momentum come from in leading edge vortex?" Tags="&lt;lift&gt;&lt;theory&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24379" PostTypeId="2" ParentId="2549" CreationDate="2016-01-16T11:21:39.450" Score="-4" Body="&lt;p&gt;It is simple. The Earth rotates from East to West. There is hence an eastward shear effect in the atmosphere. If you fly East, this shear adds to the cruising speed. Reverse case if you fly west. So more time if you fly westwards. But how much more depends on the prevailing wind-shear. This cannot be pre-determined except when you actually fly and meter the wind speed.&lt;/p&gt;&#xA;" OwnerUserId="13014" LastEditorUserId="3313" LastEditDate="2016-01-16T13:39:49.593" LastActivityDate="2016-01-16T13:39:49.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24380" PostTypeId="1" AcceptedAnswerId="24381" CreationDate="2016-01-16T11:53:50.123" Score="35" ViewCount="14341" Body="&lt;p&gt;Why do aircraft allow sliding / opening windows in cockpits? What purpose does it serve, and why the same can't be done for passenger windows as well?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yh3vl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yh3vl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="5517" LastEditDate="2016-01-27T17:11:41.187" LastActivityDate="2016-02-17T05:07:28.173" Title="Why are some windows in cockpits made openable?" Tags="&lt;cockpit&gt;&lt;windows&gt;" AnswerCount="4" CommentCount="13" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24381" PostTypeId="2" ParentId="24380" CreationDate="2016-01-16T12:31:53.267" Score="35" Body="&lt;p&gt;The opening cockpit windows do serve some purpose, like providing an additional means of evacuation during an emergency.* There have been instances where the &lt;a href=&quot;http://www.thehindu.com/2000/02/10/stories/03100005.htm&quot; rel=&quot;noreferrer&quot;&gt;crew had used the cockpit windows to escape&lt;/a&gt; during hijackings.&lt;/p&gt;&#xA;&lt;p&gt;There are other purposes like assisting in crew inspection, signaling ground crew, additional ventilation, smoke egress etc (It can also be &lt;a href=&quot;http://www.airstewardess.org/british-airways-ba-2945-pilot-threw-phone-on-runway/&quot; rel=&quot;noreferrer&quot;&gt;used for throwing things out&lt;/a&gt;, though it is not generally recommended). One main reason (atleast in the past) appears to be to improve the pilot visibility in case the windshield becomes opaque, for example.&lt;/p&gt;&#xA;&lt;p&gt;The windows are not found in all aircraft (for eg. 787 doesn't have it) and are not very easy to open (note that it opens inwards). From &lt;a href=&quot;http://usatoday30.usatoday.com/travel/columnist/getline/2006-01-30-ask-the-captain_x.htm&quot; rel=&quot;noreferrer&quot;&gt;USAToday Ask the Captain&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;First there is a locking mechanism, then either a crank which moves the entire window assembly including the frame, or a lever with which to move the window assembly. When the window is closed and locked, it is sealed shut. When open, it does not separate from the frame as the window in your car does.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Actually, FAR 25 Section 773- Pilot Compartment View &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.773&quot; rel=&quot;noreferrer&quot;&gt;requires cockpit windows to be openable&lt;/a&gt; (or some other means to have clear windshield during precipitation) :&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(b) Precipitation conditions. For precipitation conditions, the following apply:&lt;/p&gt;&#xA;&lt;p&gt;(1) The airplane must have a means to maintain a clear portion of the windshield, during precipitation conditions, sufficient for both pilots to have a sufficiently extensive view along the flight path in normal flight attitudes of the airplane.&lt;/p&gt;&#xA;&lt;p&gt;(3) The first pilot must have a window that—&lt;/p&gt;&#xA;&lt;p&gt;(i) Is openable under the conditions prescribed in paragraph (b)(1) of this section when the cabin is not pressurized;&lt;/p&gt;&#xA;&lt;p&gt;(4) The openable window specified in paragraph (b)(3) of this section need not be provided if it is shown that an area of the transparent surface will remain clear sufficient for at least one pilot to land the airplane safely in the event of—&lt;/p&gt;&#xA;&lt;p&gt;(i) Any system failure or combination of failures which is not extremely improbable, in accordance with § 25.1309, under the precipitation conditions specified in paragraph (b)(1) of this section.&lt;/p&gt;&#xA;&lt;p&gt;(ii) An encounter with severe hail, birds, or insects.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In a pressurized cabin, providing windows is not a great idea. (In addition to the increased weight), if anyone manages to open the window, it would be a recipe for disaster (depressurization -&amp;gt; oxygen masks -&amp;gt; land).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;*Many aircraft have escape ropes mounted in a compartment above the window on each side of the cockpit as in this A320:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/UfeOt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UfeOt.jpg&quot; alt=&quot;A320 cockpit&quot; /&gt;&lt;/a&gt;&#xA;Photo &lt;a href=&quot;http://www.airliners.net/photo/Thai-AirAsia/Airbus-A320-216/1470721/L/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;And a &lt;a href=&quot;https://youtu.be/lWcMtK4FwWw&quot; rel=&quot;noreferrer&quot;&gt;video&lt;/a&gt; of it being used.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-16T21:56:44.397" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24382" PostTypeId="2" ParentId="24380" CreationDate="2016-01-16T15:47:47.067" Score="8" Body="&lt;p&gt;Other answers provide good broad picture information. Let me add a specific example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The windows in my work aircraft open, and we have specifically modified them to open fully out of view and remain open. Windows that open allow me to better perform my job. Note that my aircraft is non-pressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the things we often do is drop messages to people on the ground. The open window provides a means of jettisoning that message package.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aerial photography and observation of the ground is in integral part of what we do. Being able to open the window to provide an unrestricted view can give better photo or viewing environment. Conditions such as sun glare render this an important feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, being able to open the window on a hot day can be a welcome addition to the ventilation system.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-01-16T15:47:47.067" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24383" PostTypeId="2" ParentId="24378" CreationDate="2016-01-16T16:33:11.470" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Does this vortex draw in air from above, pulling it downward and as a&#xA;  result lifting the plane up?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, the bound vortex in combination with translational flow accelerates air downwards.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Or is the vortex shed downward off the tail of the wing? How does this work?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A vortex has no beginning and no end. When the wing begins to move, the vortex starts out of nowhere and has four parts: The bound vortex which travels with the wing, one parallel starting vortex which stays in place and two free vortices which connect both, running from the wingtips to the point where the wingtips were when the wing started moving. To be precise, an infinite number of vortices of infinitely small strength is created, and some cover only the center of the wing while others run over most of the wingspan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qOi4m.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qOi4m.png&quot; alt=&quot;Idealized vortex structure&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Idealized vortex structure (own work). The wing moves to the left with the speed v. The vortices are shown as discrete lines - to be precise, the bound vortices should be a sheet of infinitesimally small vortices which extend both over the chord and the span of the wing. Chordwise, they bunch together close to the leading edge, so their average streamwise position is at one quarter of the wing's chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now let me give you my advice: If you do not want to operate or to write a potential flow code, do yourself a favor and forget all that. &lt;a href=&quot;https://aviation.stackexchange.com/questions/24190/what-is-the-lift-force-per-unit-span/24195#24195&quot;&gt;Read here&lt;/a&gt; why you must endure the vortex explanation of lift, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/16193/how-do-wings-generate-lift/16202#16202&quot;&gt;read here&lt;/a&gt; for a much more intuitive explanation of it all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If by leading edge vortex you mean the &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift/21071#21071&quot;&gt;swirling air coming off the leading edge of a highly swept wing&lt;/a&gt;, this is a result of flow separation. The inertia of the air molecules makes it impossible for them to flow around the leading edge, and they jump off the contour, leaving a volume of lower pressure behind. This pressure bends their flow path towards the wing and sucks the aircraft upwards. Since more air follows the same pattern downstream, the whole air above the wing starts to rotate while it flows downstream. This low pressure area sucks more air in from above, just like the regular low pressure region over a straight wing does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along and past the inner part of the wing this downward motion is prevalent and keeps the air spinning like the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;regular downwash&lt;/a&gt; from a straight wing. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-18T12:50:03.910" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24384" PostTypeId="2" ParentId="24380" CreationDate="2016-01-16T16:55:15.920" Score="16" Body="&lt;p&gt;In the Pilatus PC-12, the pilot's side has a &quot;DV window&quot;, a &quot;direct view windows,&quot; that is hinged at the back and opens so the pilot has an unobstructed view out forward of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This window is specifically designed to allow the pilot to land an aircraft when the windshield is iced over, and the de-icing equipment is INOP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R7xrS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R7xrS.jpg&quot; alt=&quot;DV Window on PC-12&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-16T16:55:15.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24385" PostTypeId="2" ParentId="22491" CreationDate="2016-01-16T17:24:52.770" Score="0" Body="&lt;p&gt;I read there was nothing in the specs to require autorotation like a traditional helicopter.  I also read that the glide path to accomplish an auto would be too steep to go to a run on landing, which is recommended for single engine out procedures.  The only time there is not sufficient altitude for an auto is when you are at a hover below 1800 feet, which is rediculously high to hover and I am not sure what mission would require that task. Even in a normal helicopter flying low over the trees does not allow much time to decelerate, speed up the rotor in time, and cushion landing with rotor inertia momentum.  Cushion is what the traditionalists are looking for.  Only the most superior pilot will stop all forward movement and not hit any obstacles when terminating at the ground without power.  The Osprey meets its specs.  And, all the other points are mute without the best pilot that exists at the controls, which is only the Senior Instructor Test Pilots or Acrobatic Pilots, which are not a part of the training.  Just stick with run on landings and avoid hard wood trees at the bottom. There is no need to fuss over the Osprey ability to fully autorotate when landing.&lt;/p&gt;&#xA;" OwnerUserId="13018" LastActivityDate="2016-01-16T17:24:52.770" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24386" PostTypeId="1" CreationDate="2016-01-16T18:04:27.540" Score="7" ViewCount="718" Body="&lt;p&gt;I was intrigued while reading an article by this snippet:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Examination of the V-22’s frequency response plots (&lt;a href=&quot;https://en.wikipedia.org/wiki/Bode_plot&quot; rel=&quot;nofollow&quot;&gt;Bode plots&lt;/a&gt;) in&#xA;  2000 showed that the aircraft failed to meet the basic stability&#xA;  requirements mandated for rotorcraft and was indeed PIO-prone.&#xA;  Since 2000, the Navy and Bell/Boeing have stated that the frequency&#xA;  response of the aircraft has been modified to remove this tendency.&#xA;  Updated Bode plots have not been made available to date.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My question: How does one go about obtaining frequency response plots for an aircraft? Is it a modelling exercise or an  empirical one?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.g2mil.com/V-22safety.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.g2mil.com/V-22safety.htm&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="5517" LastEditDate="2016-01-18T18:14:24.433" LastActivityDate="2016-01-26T17:01:26.730" Title="Do frequency response / Bode plots for an aircraft or helicopter come from modeling or empirical testing?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;&lt;flight-testing&gt;&lt;theory&gt;&lt;stability&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24387" PostTypeId="1" CreationDate="2016-01-16T18:17:19.970" Score="6" ViewCount="300" Body="&lt;p&gt;I watched a &lt;a href=&quot;https://www.youtube.com/watch?v=wg2T7MUULZQ&quot; rel=&quot;nofollow&quot;&gt;YouTube&lt;/a&gt; movie about &lt;a href=&quot;http://www.reactionengines.co.uk/&quot; rel=&quot;nofollow&quot;&gt;Reaction Engines&lt;/a&gt; development of the Sabre engine which main feature is cooling intake air. However, I cannot find an overview of the temperature of intake air at different airspeed levels. I am looking for an overview based on speed of sound levels and the increase on intake air temperatures.&lt;/p&gt;&#xA;" OwnerUserId="8664" LastEditorUserId="19" LastEditDate="2017-06-01T13:59:47.707" LastActivityDate="2017-06-01T13:59:47.707" Title="What is the temperature of intake air at several speed of sound intervals from 1x to 10x?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;temperature&gt;&lt;inlet&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24388" PostTypeId="2" ParentId="24352" CreationDate="2016-01-16T19:47:30.110" Score="2" Body="&lt;p&gt;My father has built a small plane and talks about this problem (incidentally it is an RV through Van's too).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a very common understanding amongst the community involved in building RV's. When you sell a plane, you are incurring significant liability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A point not really mentioned in the other answers is that it takes a certain type of person to build a plane. Many of those people are... let's say less than interested in someone else taking their money, especially through a lawsuit resulting from pilot error, which is probably immensely more likely than build defects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many homebuilders also are pretty financially well off, so they have a big target on their back in a litigious society.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anecdotally I know of at least one RV that has an interesting post-flying life. It currently is hanging over an office space for a startup company as a very interesting and expensive decoration. The reason it is there, and not sold, is the same reason as the above.&lt;/p&gt;&#xA;" OwnerUserId="3675" LastActivityDate="2016-01-16T19:47:30.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24389" PostTypeId="2" ParentId="24369" CreationDate="2016-01-16T19:59:08.873" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://aviation-safety.net/&quot; rel=&quot;nofollow&quot;&gt;Aviation Safety Network&lt;/a&gt; is another good place to look. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-01-16T19:59:08.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24390" PostTypeId="1" CreationDate="2016-01-16T20:13:29.110" Score="9" ViewCount="1324" Body="&lt;p&gt;I was just reading about a tripropellent rocket engine that apparently passed all tests and was ready for flight before the program was cancelled in the early 90's. The engine was the &lt;a href=&quot;http://www.astronautix.com/engines/rd701.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;RD-701&lt;/a&gt; for the &lt;a href=&quot;http://www.astronautix.com/lvs/maks.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;MAKS spaceplane&lt;/a&gt; program. It used kerosene and liquid oxygen before switching to liquid hydrogen.&lt;/p&gt;&#xA;&lt;p&gt;So I'm now thinking about tripropellant jet engines. If we had a small tank of liquid hydrogen to either mix with the regular jet fuel or replace it for a short while, would this viably improve fuel economy for large commercial airplanes?&lt;/p&gt;&#xA;&lt;p&gt;(I've heard that jet engines can easily run on almost anything that burns, so presumably it would be easy to get a jet running on hydrogen. Correct me if I'm wrong.)&lt;/p&gt;&#xA;&lt;p&gt;There are many types of efficiencies, so let me be clear about which one I'm interested in: Fuel economy, as in miles per passenger-gallon.&lt;/p&gt;&#xA;&lt;p&gt;Let's ignore any logistics on the ground about obtaining and storing the hydrogen. However, storage aboard the airplane itself should certainly be considered and might be a very detrimental factor, as might flammability. I'm pretty sure we would at least need double-walled, vacuum insulated tanks to let us store that hydrogen throughout the flight. They might be twice as heavy as normal tanks.&lt;/p&gt;&#xA;&lt;p&gt;If you know anything about hydrogen, its chemical energy (per mass) is greater than gasoline....by a factor of 3 IIRC. The Lower Heating Values are around 120 versus 40. So we might all ask why not just use liquid hydrogen in everything and what is taking so long? Well apart from cryogenic considerations, it's not very dense at all. We would need a huge tank maybe even bigger than the airplane itself to store the necessary hydrogen, even tho that huge volume of hydrogen would still weigh less than the necessary jet fuel.&lt;/p&gt;&#xA;&lt;p&gt;I think the idea of tripropellant engines is to allow &lt;strong&gt;some&lt;/strong&gt; hydrogen with a not-so-overwhelming tank. The tank would only be as big as we can reasonably handle. Therefore we use &lt;strong&gt;some&lt;/strong&gt; hydrogen to get a bonus in fuel economy.&lt;/p&gt;&#xA;&lt;p&gt;P.S. I'm not really asking this from a &amp;quot;green&amp;quot; perspective. Hydrogen and oxygen burn to form pure water exhaust, which sounds so harmless, but water vapor is actually a very potent greenhouse gas, much more potent than CO2 molecule-for-molecule---especially when released at high altitudes. I'm asking this purely from a fuel-economy standpoint.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2020-09-23T12:00:42.313" LastActivityDate="2020-09-23T12:00:42.313" Title="Are tripropellant jet engines a viable way to increase fuel efficiency for large commercial airplanes?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;fuel&gt;&lt;efficiency&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24392" PostTypeId="2" ParentId="24387" CreationDate="2016-01-16T22:04:02.897" Score="5" Body="&lt;p&gt;Thermodynamics is your friend here. Compression in a ram intake is ideally isentropic (meaning entropy stays constant, so the whole process is reversible). In reality, some viscous losses cannot be avoided but are in the low percentage range in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/24010/which-supersonic-airplanes-use-pitot-air-intakes/24017?s=1%7C0.2207#24017&quot;&gt;well designed intake&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The temperature $T$ in &lt;a href=&quot;http://www.grc.nasa.gov/WWW/K-12/airplane/compexp.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;isentropic compression&lt;/a&gt; from a state 1 to a state 2 can be calculated from the pressure $p$ and the ratio of specific heats $\kappa$:&#xA;$$T_2 = T_1\cdot\left(\frac{p_2}{p_1}\right)^{\frac{\kappa-1}{\kappa}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.engineeringtoolbox.com/specific-heat-ratio-d_608.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;$\kappa$ is 1.4 for air&lt;/a&gt;, so if the saber engine flies in air 250 K cold (-23.15°C) and a pressure of 500 mbar, and the intake compresses this air by a factor of 10 to 5,000 mbar, the temperature will ideally rise to 483 K (210°C). In reality, this might well be 220°C or 230°C due to &lt;a href=&quot;https://aviation.stackexchange.com/questions/23747/what-is-the-typical-temperature-of-an-airliners-hull-during-flight/23783?s=1%7C0.1148#23783&quot;&gt;viscous heating&lt;/a&gt; of the air in the process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How the temperature ratio depends on flight Mach number $Ma$ (again, ideally) can be seen from this plot, based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717#14717&quot;&gt;this way&lt;/a&gt; to calculate the pressure rise:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yvnbI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yvnbI.png&quot; alt=&quot;temperature ratio over Mach number&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-01-16T22:33:47.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24393" PostTypeId="2" ParentId="24380" CreationDate="2016-01-16T23:17:28.837" Score="-1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;and why the same can't be done for passenger windows as well?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Anybody who opens even a bit a potential airliner sliding window near his seat creates in the entire plane the conditions existent on the top of Mount Everest, even worse. Nobody wants to stay in such an environment. In conclusion passenger sliding windows serve no purpose.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2016-01-16T23:17:28.837" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24394" PostTypeId="2" ParentId="4953" CreationDate="2016-01-16T23:59:50.440" Score="2" Body="&lt;p&gt;No propeller-driven aircraft has ever exceeded Mach 1. The Brits did high-Mach dive tests in Spits out to high Mach numbers but never to Mach 1. In the US, Herb Fisher did high-Mach dive testing in a modified P47 and never reached Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is propeller over-speed and high drag rise on the propeller disk.&#xA;It simply can't be done.&lt;/p&gt;&#xA;" OwnerDisplayName="user13024" LastEditorUserId="4474" LastEditDate="2016-06-07T06:01:03.833" LastActivityDate="2016-06-07T06:01:03.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24395" PostTypeId="1" AcceptedAnswerId="24402" CreationDate="2016-01-17T00:18:03.873" Score="5" ViewCount="1337" Body="&lt;p&gt;This question relates to &lt;a href=&quot;http://leehamnews.com/2015/12/11/bjorns-corner-twins-or-quads/&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article at Leeham&lt;/a&gt;, essentially this article challenges the concept that twin engined airliners are more efficient than quad engined. However the article fails to show the data and prove the arguments. My question is asked to those who are able to confirm the arguments of the article. I will describe my argumentation and formulate the specific answer at the end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, in the industry it is preferred to use twin engines vs quad engines based on the following arguments:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Twin engines have less maintenance cost (2 vs 4).&lt;/li&gt;&#xA;&lt;li&gt;Less aerodynamic interference and weight.&lt;/li&gt;&#xA;&lt;li&gt;Less cost (4 enginers are more expensive including systems for the same power)&lt;/li&gt;&#xA;&lt;li&gt;However less bypass ratio for twin engines and overdimensioning due to compliance with the take-off certification at engine failure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Netly, twin engines win against quad engines except in the past for &lt;a href=&quot;https://aviation.stackexchange.com/questions/19538/why-does-the-a340-have-4-engines-instead-of-2&quot;&gt;ETOPS certification&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, previous statement is my understanding of the trade-off between twin and quad. The article argues (using always seat mile costs) the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Little efficiency between B777-200ER and A340-300 / A380-800.&lt;/li&gt;&#xA;&lt;li&gt;4 CFMs engines or A380-800 4 engines have less maintenance costs than B777-200ER 2 engines. Fleet of CFM is higher as well.&lt;/li&gt;&#xA;&lt;li&gt;Argues that B777-200ER requires more powerfull engines. This argument does not contribute, as finally is an efficiency driver and the important is the first argument.&lt;/li&gt;&#xA;&lt;li&gt;Previous comparisons are not valid to previous low bypass engines.&lt;/li&gt;&#xA;&lt;li&gt;Article is not introducing airplane cost in the comparison (important for capital costs)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, my explicit questions are the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can somebody demonstrate with evidences that the efficiency of B777-300ER is lower or higher than A340-300 or A380-800?&lt;/li&gt;&#xA;&lt;li&gt;Can somebody demonstrate with evidences that the maintenance cost of the engines of B777-300ER is lower or higher than A340-300 or A380-800?&lt;/li&gt;&#xA;&lt;li&gt;Can somebody support further my arguments or support the article?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2018-12-27T03:49:15.890" Title="Is the twin vs quad engine industry preference really challenged?" Tags="&lt;aircraft-design&gt;&lt;multi-engine&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24396" PostTypeId="2" ParentId="24395" CreationDate="2016-01-17T08:55:20.263" Score="8" Body="&lt;p&gt;Why would Airbus go to the effort of developing the A330 when they could offer the A340? Both have the same airframe and differ mainly in the number of engines. With &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow noreferrer&quot;&gt;ETOPS&lt;/a&gt; requirements at the time of development (when they were known as TA9 and TA11) being just 2 hours (ETOPS 180 operations were only begun in 1989), the only reason for developing the 4-engined variant was its capability of flying long overwater routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time it takes to check an engine is the same regardless of size, so having only two of them saves time and money. In addition, the higher power reserves of a two-engined aircraft allow for higher climb speeds and enable it to reach the most efficient cruise altitude faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Today, most airliner engines are no longer owned by the airlines, but &lt;a href=&quot;https://aviation.stackexchange.com/questions/8270/manufacturer-independent-jet-engine-mro/8283#8283&quot;&gt;leased from the engine manufacturer&lt;/a&gt;. They offer a simple thrust per hour model where the airline knows exactly how much the engine will cost them over time, maintenance included. The only open issue is how long the airliner is grounded due to unforeseen maintenance, and with four engines per aircraft the number of unforeseen snafus is twice that of a twin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, the airline is in the best position to judge how expensive a seat-mile in any of their aircraft is. Engine cost can be calculated very precisely, so every airline should have a very clear picture of how expensive their twins and four-engined aircraft are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a small chance that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW1000G&quot; rel=&quot;nofollow noreferrer&quot;&gt;geared turbofans&lt;/a&gt; which are &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW1000G#Applications&quot; rel=&quot;nofollow noreferrer&quot;&gt;now being introduced&lt;/a&gt; will give the A340 an edge over a twin variant. The higher thrust class of large twins makes a geared fan currently impossible, so a four-engined aircraft will have an edge because it can use a more advanced engine.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-12-27T03:49:15.890" LastActivityDate="2018-12-27T03:49:15.890" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="24399" PostTypeId="1" AcceptedAnswerId="24405" CreationDate="2016-01-17T11:48:56.323" Score="6" ViewCount="2649" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot_tube&quot; rel=&quot;nofollow noreferrer&quot;&gt;pitot tube&lt;/a&gt; is used to measure the air pressure later converted into air speed. However air pressure varies according to several elements, including the location related to the wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ijRXq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ijRXq.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;http://www.av8n.com/how/#contents&quot; rel=&quot;nofollow noreferrer&quot;&gt;av8n.com&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On one hand the probe, depending on its location, could measure the pressure in the free stream, in the high velocity stream, or in the low velocity stream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, pitots are found at various locations, e.g:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EXwxD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EXwxD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;On the fuselage, far from the wing, B-737 (&lt;a href=&quot;http://www.microsiervos.com/archivo/aerotrastorno/informe-final-accidente-af-447-rio-janeiro-paris-accidentado-2009.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yc8Ou.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yc8Ou.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;On the vertical stabilizer, kit Nemesis NXT (&lt;a href=&quot;http://www.airventure.de/reno06_3_sport.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6dCsA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6dCsA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Under the wing, Cessna 172 (&lt;a href=&quot;http://www.aerospaceweb.org/question/instruments/q0251.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore when the probe is fixed to the fuselage or to the stab, depending on the angle of attack, it can be rotated into the slowed down or the accelerated portion of the stream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you shed some light on what is usually measured by the pitot? Does the pitot indicate different pressures if placed in the different stream areas (free, accelerated, decelerated)? If so:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is usually measured by the probe?&lt;/li&gt;&#xA;&lt;li&gt;What is usually displayed on the speed indicator?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit: While I needed to select a single answer, several other answers contain additional interesting elements and deserve votes as well.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-01-19T07:30:43.777" LastActivityDate="2021-03-19T08:54:13.893" Title="Which air stream pressure / speed is measured by the pitot?" Tags="&lt;aircraft-design&gt;&lt;airspeed&gt;&lt;pitot-static&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24400" PostTypeId="2" ParentId="24390" CreationDate="2016-01-17T12:21:25.427" Score="5" Body="&lt;p&gt;Yes, you can reduce takeoff mass by exchanging kerosene with hydrogen, but only above a minimum volume where the increased weight of the tank does not cancel out this advantage. But any manufacturer introducing such an aircraft today would immediately hit the problem of fuel availability - there is simply no infrastructure for hydrogen at airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historically, the military paved the way for infrastructure improvements, and with aerial refueling, satellite technology and the vanishing importance of long-range platforms (except for unmanned reconnaissance maybe) there is no pressing need today to roll out the hydrogen infrastructure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that project &lt;a href=&quot;https://aviation.stackexchange.com/questions/22765/why-did-the-cl-400-suntan-have-engines-on-the-ends-of-its-wings/22767?s=2%7C0.0678#22767&quot;&gt;Suntan&lt;/a&gt; (which became the Lockheed CL400) invested into the liquid hydrogen infrastructure that enabled the use of cryogenic rockets in the Apollo program. Maybe a future military hypersonic vehicle will do the same for hydrogen in civilian air transport, but I am skeptical that this will happen in my lifetime. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-01-17T12:21:25.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24401" PostTypeId="1" CreationDate="2016-01-17T12:38:19.173" Score="3" ViewCount="871" Body="&lt;p&gt;I work as ATC in Korea and recently, I have some question about winter altimeter setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my facility, we use winter altimeter adjustment because the aircraft's pressure altitude is lower than true altitude in winter. I know this is due to air density difference in winter and summer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, can the altimeter setting (inch or QNH) include this adjustment? I know that the altimeter setting which ATC gives to the pilot changes every time according to the ground QNH condition. If the altimeter setting can include the adjustments, it would be convenient to ATC and pilot.&lt;/p&gt;&#xA;" OwnerUserId="12972" LastEditorUserId="167" LastEditDate="2016-01-17T21:31:14.950" LastActivityDate="2016-01-18T16:26:45.877" Title="Do pressure altimeters take into account differences in temperature?" Tags="&lt;altimeter&gt;&lt;cold-weather&gt;&lt;qnh&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2016-01-19T01:43:50.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="24402" PostTypeId="2" ParentId="24395" CreationDate="2016-01-17T13:02:49.320" Score="6" Body="&lt;p&gt;The main problem with the article as far as I can see is that they offer little in terms of evidence. The best we could do in the absence of their 'propriety model' is to use real world examples.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The best one is to use the Airbus experience in developing A330/340 which had little difference than twin/quad engines. While A330 is still in production, A340 has been stopped, indicating customer indifference. It is unlikely that the customers would've stopped operating A340 based on some myths.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another thing to note is the present operation- Even in case of long-haul routes, where quads like A380 must be more efficient (in short routes, the more powerful engines of twins should help them reach cruise quicker), more twin engines are used compared to quads. In fact, the 777 LR is the predominant aircraft operated in ultra-long haul routes, followed by A380.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Also, look at the latest iteration of the 747, 747-8. Boeing is having trouble having takers for the jet (similar story in A380). In airline industry, where every single cent saved counts, almost all airlines are preferring twins over quads. As 747-8 has most of the aerodynamic improvements of current generation aircraft, maintenance should be an important factor in airline's decision in not selecting it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another important point- no quad is under development right now. With more and more aircraft development being done in collaboration with airlines, this is significant. in fact, since ETOPS came into force, quads are being slowly phased out (like trijets before).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The article never makes any point to support its assertion that the maintenance cost of twins and quads are the same. At the simplest level, assuming that they both have the same high-efficient engines, quads should take twice as the twins in man-hours for maintaining. For airlines, where engine maintenance takes a significant chunk of total maintenance, this is important. Also, more engines means more points of failure, which practically increases the inventory.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;While one could argue that the quads &lt;em&gt;can&lt;/em&gt; have better designs compared to twins (by virtue of improves wing bending relief, for example), this is questionable and the associated systems (fuel, fire suppression) would add more complexity and weight, compared to the twins.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-17T13:02:49.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24403" PostTypeId="2" ParentId="24399" CreationDate="2016-01-17T13:04:11.023" Score="7" Body="&lt;p&gt;The first thing to have in mind is that a pitot tube is NOT measuring speed: the pitot tube measures pressure and later on the airplane (flight management system in a modern airplane) calculates the speed based on pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More specifically the pitot tube calculates the stagnation pressure which is the sum of static pressure (what you show in your picture) and the dynamic pressure (pressure obtained by stopping the air).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The total pressure remains constant in the external free flow in normal airplane operations BUT will not remain constant in the boundary layer, which is a small region close to the wall. The boundary layer grows with the distance downwash along the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I explained here justifies the following design solutions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pitot tubes are usually installed with an small distance to the walls &quot;like floating&quot; in order to be outside the boundary layer and free of loses on the stagnation pressure.&lt;/li&gt;&#xA;&lt;li&gt;Pitot tubes are never installed at the tail of the airplane, in order to avoid high thickness of boundary layer (could reach 1 meter).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="938" LastEditDate="2016-01-17T16:21:19.983" LastActivityDate="2016-01-17T16:21:19.983" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24404" PostTypeId="1" CreationDate="2016-01-17T13:36:41.293" Score="6" ViewCount="11777" Body="&lt;p&gt;I'm interested in knowing what aiming points on runways are used for:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why do some runways have aim points and some do not?&lt;/li&gt;&#xA;&lt;li&gt;We say that pilots must use the maximum length of the runway. Therefore, why don't we touch down on or near the threshold lines as our aiming point? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13033" LastEditorUserId="12720" LastEditDate="2016-01-17T18:46:22.110" LastActivityDate="2016-01-18T07:57:58.423" Title="What are runway Aiming Point markers used for?" Tags="&lt;runways&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24405" PostTypeId="2" ParentId="24399" CreationDate="2016-01-17T14:24:55.140" Score="7" Body="&lt;p&gt;You're correct that there are a number of parameters that influence the measurement of air data in general. For example, the total pressure measurement (as done using the Pitot tube) is influenced by,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Angle of attack&lt;/li&gt;&#xA;&lt;li&gt;Reynolds number&lt;/li&gt;&#xA;&lt;li&gt;Mach number&lt;/li&gt;&#xA;&lt;li&gt;Velocity gradients&lt;/li&gt;&#xA;&lt;li&gt;Proximity to surfaces (wings, fuselage etc.)&lt;/li&gt;&#xA;&lt;li&gt;Flow steadiness&lt;/li&gt;&#xA;&lt;li&gt;Probe geometry&lt;/li&gt;&#xA;&lt;li&gt;Compressibility and shock&lt;/li&gt;&#xA;&lt;li&gt;Shape of the measuring head etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In case of total pressure, as long as the (pitot) tube is outside the boundary layer and the flow angle is less (&amp;lt;10% usually), the error is negligible. The following image shows the error due to incidence angle at different speeds for different head designs. Here, $H_{0}$ is the Free stream total head es measured in the tunnel intake and $H_{1}$ is the head measured by the instrument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zYYZ5.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zYYZ5.png&quot; alt=&quot;M-0.4 Pitot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mfT9W.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mfT9W.png&quot; alt=&quot;M-0.84 Pitot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Tests on the Effect of Incidence on some Pressure Heads at high Subsonic Speeds&lt;/em&gt; by E W. E. Rogers, D.I.C., &amp;amp; SC and C. J. Berry, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the same paper:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Tunnel measurements have shown that up to at least M = 0.75 the loss in total head on a Venturi-shrouded pitot was less than 0.5% for incidences of up to about 40$^{\circ}$. This compares with a limit of 9$^{\circ}$ at M = 0.7 to 0.85 for 0.5% loss on the pitot section of a standard Mk.VIIIA instrument and 17$^{\circ}$ at M = 0.7 to 0.9 on the small pitot heads in general use ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Static pressure measurement errors are similar; however, there are some points where the errors in static pressure measurement in the fuselage of the aircraft are minimal and the static ports can be mounted at these points (in addition to the static port in pitot-static tube).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4rIQ5.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4rIQ5.png&quot; alt=&quot;Static Pressure Points&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Airdata Measurement and Calibration&lt;/em&gt; by Edward A. Haering, Jr.&#xA;NASA Dryden Flight Research Center&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be better if the static ports are mounted at these points in order to reduce the error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the above data, it can be seen that for GA and commercial aircraft, the position of the pitot-static tube can be located with reasonable accuracy at a number of points as long as it is in the undisturbed flow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point is that the pitot-static tube measures pressure and the Air Data Computer (usually) converts it into the required parameter (for eg. speed). So,if the errors are known (during flight testing, for example), the instruments could be calibrated as per requirements. In general, typical methods used for calibration are,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Tower Flyby&lt;/li&gt;&#xA;&lt;li&gt;Trailing Static or Trailing Cone&lt;/li&gt;&#xA;&lt;li&gt;Pacer Aircraft&lt;/li&gt;&#xA;&lt;li&gt;Radar Tracking&lt;/li&gt;&#xA;&lt;li&gt;Dynamic Maneuvers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;among others. Other electronic methods are also used for calibration purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to achieve the very high accuracy required during flight testing and to serve as a reference, air-data booms are sometimes used in experimental and test aircraft, as can be seen in the F-35 below, whose data can be used for calibration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DsBXh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DsBXh.jpg&quot; alt=&quot;F-35&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Cockpit_and_Air_Data_Boom_F-35C.jpg#/media/File:Cockpit_and_Air_Data_Boom_F-35C.jpg&quot; rel=&quot;noreferrer&quot;&gt;Cockpit and Air Data Boom F-35C&lt;/a&gt;&quot; by &lt;a href=&quot;//commons.wikimedia.org/wiki/File:CF-1_flight_test.jpg&quot; rel=&quot;noreferrer&quot; title=&quot;File:CF-1 flight test.jpg&quot;&gt;File:CF-1 flight test.jpg&lt;/a&gt;: Andy Wolfederivative work: &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Berg2&quot; rel=&quot;noreferrer&quot; title=&quot;User:Berg2&quot;&gt;Berg2&lt;/a&gt; (&lt;a href=&quot;//commons.wikimedia.org/wiki/User_talk:Berg2&quot; rel=&quot;noreferrer&quot; title=&quot;User talk:Berg2&quot;&gt;talk&lt;/a&gt;) - &lt;a href=&quot;//commons.wikimedia.org/wiki/File:CF-1_flight_test.jpg&quot; rel=&quot;noreferrer&quot; title=&quot;File:CF-1 flight test.jpg&quot;&gt;File:CF-1 flight test.jpg&lt;/a&gt; (cropped). Licensed under Public Domain via &lt;a href=&quot;//commons.wikimedia.org/wiki/&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some extreme cases, the nose mounted airdata systems which are typically used (to minimize influence of aircraft on measurements) can be unsuitable due to specific reasons. A good example is the &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwj22rP2hLHKAhXG6xQKHZHtBWAQFggbMAA&amp;amp;url=http%3A%2F%2Fwww.nasa.gov%2Fcenters%2Fdryden%2Fpdf%2F88208main_H-1674.pdf&amp;amp;usg=AFQjCNFgnwtQcP0vloUVYu3lqF8MgMu-Cg&amp;amp;bvm=bv.112064104,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;NASA F-18 High Alpha Research Vehicle&lt;/a&gt; (HARV) program, where, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... a noseboom was deemed unacceptable for this program. At high angles of attack, the noseboom has a significant effect on the forebody aerodynamics and thus on the stability and control of the aircraft. As a result, wingtip mounted sensors and a flush nose-cone mounted sensor were used.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-17T14:24:55.140" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24406" PostTypeId="2" ParentId="2198" CreationDate="2016-01-17T15:30:05.150" Score="0" Body="&lt;p&gt;As stated previously bandwidth cost and coverage of satellite communication accross the ocean is a major issue for something which doesn't directly make the airlines make money (contrary to in flight data for PAX). Even if you do it too often you could reach the limits of the actual satellite communication system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is well studied by the report made following the AF447 crash : &lt;a href=&quot;http://www.bea.aero/en/enquetes/flight.af.447/triggered.transmission.of.flight.data.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.bea.aero/en/enquetes/flight.af.447/triggered.transmission.of.flight.data.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To reduce the cost of it the question asked is &quot;can the plane transfer its position when it detects an unusual situation&quot;.&lt;/p&gt;&#xA;" OwnerUserId="3277" LastActivityDate="2016-01-17T15:30:05.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24409" PostTypeId="2" ParentId="24399" CreationDate="2016-01-17T21:27:57.000" Score="0" Body="&lt;p&gt;This is a link to the Instrument Pilot handbook offered by the FAA:&#xA;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;page 97 explains the pitot-static system. It is a simple answer with illustrations. It might not explain every nuance of the system, but it is enough for a pilot to pass his exam!&lt;/p&gt;&#xA;" OwnerUserId="13040" LastActivityDate="2016-01-17T21:27:57.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24411" PostTypeId="2" ParentId="24401" CreationDate="2016-01-17T22:52:48.167" Score="3" Body="&lt;p&gt;You can't just adjust the QNH setting to compensate. The temperature adjustment is not linear. The error increases with altitude, so when the altimeter is set for QNH the error at field level is zero. But it increases the higher you go. It's not just everything being X number of feet higher or lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your question you say &quot;the aircraft's pressure altitude is lower than true altitude in winter.&quot; That's backwards. The actual altitude is actually &lt;em&gt;lower&lt;/em&gt; than what is indicated by the pressure alt. This can run the risk of colliding with terrain if the pilot doesn't adjust. In fact, exceptionally hot weather causes an error also, but in the opposite direction. The reason this doesn't need to be compensated is because the actual altitude will be &lt;em&gt;higher&lt;/em&gt; than indicated so it doesn't create a danger of hitting terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From answers to &lt;a href=&quot;https://aviation.stackexchange.com/q/22478/8730&quot;&gt;another question&lt;/a&gt; an aircraft with an FMS can be set to automatically adjust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem seems to be in who's responsible for making the adjustment (ATC or pilot) and being clear on whether the altitude announced is adjusted or not. According to the answer from wbeard52, in the US the FAA has established a list of airports with cold weather procedures that require the pilot to do the compensation and announce the corrected alt to the controller. According to Sami's answer, in the EU the controller makes the corrections under radar coverage, and the pilot makes the correction without. It would appear from your question that in Korea they have decided to have you make the corrections as controller. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-18T16:26:45.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24413" PostTypeId="1" CreationDate="2016-01-18T00:52:32.910" Score="21" ViewCount="3086" Body="&lt;p&gt;I saw this photo at &lt;a href=&quot;https://aviation.stackexchange.com/questions/17676/why-cant-horizontal-stabilizers-be-longer-than-they-are-today?rq=1&quot;&gt;another interesting question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/47cpB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/47cpB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's an open square panel. What is it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. Any tag suggestions are welcome. All I could think of was &quot;tail&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: are there any other tags for this kind of thing? The APU tag seems to be a crystal ball because I had no idea what it was at the time.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-19T01:28:05.900" Title="What is this open panel at the rear of this airplane?" Tags="&lt;boeing&gt;&lt;apu&gt;&lt;tail&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24414" PostTypeId="1" AcceptedAnswerId="24424" CreationDate="2016-01-18T01:00:42.643" Score="47" ViewCount="24499" Body="&lt;p&gt;Most large aircraft and some fighters have blunt, rounded nose cone. OTOH many fighters (that don't use the nose for air intake) and notably the two supersonic airliners (Concorde, TU-144) have the sharp tip for a nose cone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the aerodynamic justification for that? What advantages and disadvantages does the &quot;blunt&quot; nose cone provide - or why don't all airplanes have the sharp spike nose cone (which &quot;feels&quot; like the obviously optimal aerodynamic choice - obviously that &quot;feel&quot; is somehow flawed?)&lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="7611" LastEditDate="2016-01-18T15:07:03.097" LastActivityDate="2020-05-29T04:16:59.860" Title="Why/when is the blunt nose better?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;theory&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24415" PostTypeId="2" ParentId="24413" CreationDate="2016-01-18T01:46:19.003" Score="31" Body="&lt;p&gt;It is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;noreferrer&quot;&gt;Auxiliary Power Unit (APU)&lt;/a&gt; inlet door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wyqvN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wyqvN.jpg&quot; alt=&quot;APU inlet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2010_q4/3/&quot; rel=&quot;noreferrer&quot;&gt;Boeing Aero Magazine&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="8730" LastEditDate="2016-01-19T01:28:05.900" LastActivityDate="2016-01-19T01:28:05.900" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24416" PostTypeId="2" ParentId="24414" CreationDate="2016-01-18T02:19:11.543" Score="38" Body="&lt;p&gt;Aircraft design is full of compromises. In case of aircraft nose design, the main factor is to reduce drag. As you yourself noted, the main difference is in flow regime, i.e. subsonic and supersonic. There are different types of drag- skin (or friction) drag, form drag and wave drag (which becomes important only at supersonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For subsonic flow, the main drag components are the first two- skin friction and form drag. Here, if we consider the fuselage to be a cylinder with the nose in front (which is a pretty good approximation), the blunt nose configuration gives a lesser drag coefficient (non-dimensional drag) compared to the conical or sharp nosed one. This means that all other things being equal, the blunt nose has lesser drag compared to sharp ones in subsonic flow. In particular, the blunt nose has lesser surface area compared to the sharp, long ones and thus lesser skin friction drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G5A0V.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G5A0V.png&quot; alt=&quot;Forebody Drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Fluid Dynamic Drag by Hoerner&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the above figure, you can see that the blunt nose is actually better compared to a sharp nose as far as drag is concerned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o8AHc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o8AHc.png&quot; alt=&quot;3D Drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Fluid Dynamic Drag by Hoerner&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as the aircraft goes to supersonic flow, the main concern becomes wave drag. Here, the sharp nose keeps the shock wave clear of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z2XKt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z2XKt.jpg&quot; alt=&quot;Shock wave&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from wotzup.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing is that in a sharp section, the cross sectional area varies gradually, which helps in prevention of local acceleration (which can result in local sonic conditions). This is the reason why you see aircraft that fly subsonic over most of their flight regime have blunt noses, while those fly supersonic over most of their flight path have sharp noses. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course there are other points to consider too:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The manufacturing cost of the sharp nose is usually greater than a blunt nose (has more area, for one).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A long, sharp nose will affect visibility during landings (Concorde had a droop-down nose because of this). Also, parking in airport ramps is going to be difficult.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A sharp nose will have lesser volume (for mounting radar, for example). As a result, most supersonic aircraft actually have a sightly modified nose section (elliptical or oogival, for example), especially, fighter aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PcXxL.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PcXxL.gif&quot; alt=&quot;Nose cone volume&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from spaceflightsystems.grc.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen, an elliptical section with same base diameter and height has double the volume of a conical one. In some cases, where the nose landing gear retracts into the nose (like A350), this will be important.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-18T02:19:11.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24417" PostTypeId="2" ParentId="24404" CreationDate="2016-01-18T02:20:13.367" Score="4" Body="&lt;p&gt;I'll try to answer just the first portion. The aiming point marking basically serves as a visual aiming point for a landing aircraft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aEUHJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aEUHJ.png&quot; alt=&quot;Aiming point&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from code7700.com&lt;/p&gt;&#xA;&lt;p&gt;They are not found in all runways because the requirement is based on the aerodrome code number and they are not required in all cases. Aerodrome Reference Code from &lt;a href=&quot;https://drive.google.com/file/d/0B2u8czVndcm6ckVKZ1RsYUtoT1U/edit?pref=2&amp;amp;pli=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Annex 14 Volume I&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Ma8y.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Ma8y.png&quot; alt=&quot;Aerodrome Code&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Table from ICAO Annex 14 Vol I&lt;/p&gt;&#xA;&lt;p&gt;From the Same reference:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;5.2.5.1 An aiming point marking shall be provided at each approach end of a paved instrument runway where the code number is 2, 3 or 4.&lt;/p&gt;&#xA;&lt;p&gt;5.2.5.2 Recommendation.— An aiming point marking should be provided at each approach end of:&lt;/p&gt;&#xA;&lt;p&gt;a) a paved non-instrument runway where the code number is 3 or 4;&lt;/p&gt;&#xA;&lt;p&gt;b) a paved instrument runway where the code number is 1;&#xA;when additional conspicuity of the aiming point is desirable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-18T02:20:13.367" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24419" PostTypeId="2" ParentId="24373" CreationDate="2016-01-18T02:45:22.323" Score="3" Body="&lt;p&gt;There isn't a simple easy-to-use API for this, but there is a plethora of model data you can use to derive a proxy for cloud locations.  Specifically the &lt;a href=&quot;http://www.nco.ncep.noaa.gov/pmb/products/gfs/&quot; rel=&quot;nofollow noreferrer&quot;&gt;GFS&lt;/a&gt; and &lt;a href=&quot;http://www.ecmwf.int/en/forecasts/datasets&quot; rel=&quot;nofollow noreferrer&quot;&gt;ECMWF&lt;/a&gt; both run global forecast models and there are various regional models (e.g. in the US we have &lt;a href=&quot;http://nomads.ncdc.noaa.gov/data.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;NAM, RAP, HRRR, ensembles&lt;/a&gt; and various high-res WRF runs).  The GFS, for example, provides relative humidity and cloud water mixing ratio at its vertical gridpoints and from these you could model where clouds are likely to be.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is certainly possible to model cloud bases with publicly available datasets as demonstrated by the folks at &lt;a href=&quot;http://sunsetwx.com/about-the-model/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SunsetWX&lt;/a&gt; can attest to, as cloud base heights play a role in vivid colors at sunset.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This won't be an easy-to-query API, but well within the research of someone willing to work with existing forecast and observational data (satellite (visible, IR, water vapor), soundings, profilers, radar, etc) to build a predictive cloud location model.  There may already be published literature on this and you might get more information over on &lt;a href=&quot;https://earthscience.stackexchange.com/&quot;&gt;Earth Science stack echange&lt;/a&gt; if that is the case or if there is some dataset already out there that I'm not personally aware of.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2017-04-13T12:50:29.723" LastActivityDate="2016-01-18T02:45:22.323" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24421" PostTypeId="2" ParentId="24404" CreationDate="2016-01-18T07:57:58.423" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;We say that pilots must use the maximum length of the runway. Therefore, why don't we touch down on or near the threshold lines as our aiming point?&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No. Using maximum length of the runway just follows from more general rule to have as much margin of error as possible. But errors can happen in &lt;em&gt;both&lt;/em&gt; directions. Landing long is more common, so it makes sense to leave the largest margin at the end of the runway, but landing short also happens, so some margin should be left at the start too. The 1000 ft is considered reasonable margin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that for small aircraft, &lt;a href=&quot;http://www.av8n.com/how/htm/landing.html#sec-touchdown-point&quot; rel=&quot;nofollow&quot;&gt;some&lt;/a&gt; advocate using the middle part of the runway and leaving about as much margin at both ends. However the PAPI and ILS can't be adjusted for each aircraft, so they are installed at the standard 1,000 ft past threshold mark.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides, pilots don't have to use full length of the runway. There is also &lt;a href=&quot;https://en.wikipedia.org/wiki/Land_and_hold_short_operations&quot; rel=&quot;nofollow&quot;&gt;LAHSO&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-01-18T07:57:58.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24424" PostTypeId="2" ParentId="24414" CreationDate="2016-01-18T13:18:09.873" Score="39" Body="&lt;p&gt;In &lt;strong&gt;subsonic&lt;/strong&gt; flow the air can react to the approaching vehicle since the pressure field around it extends forward, too. This means that a suction area on one side of the fuselage or wing will already start to pull molecules in before they reach the vehicle itself which causes this suction. A round nose allows the flow to come from a range of angles without creating too much drag. Aerodynamically speaking, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9955/can-a-steady-flow-have-stagnation-points/9958?s=2%7C0.3420#9958&quot;&gt;stagnation point&lt;/a&gt; can be moved without problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;strong&gt;supersonic&lt;/strong&gt; flow, the air has no indication of the approaching vehicle. The first contact will cause a sudden change in direction, called a shock. For drag reduction it is important to make the shock as weak as possible, which means that the change in direction should be as small as possible. This can best be achieved by a slender, pointy tip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the downward position of the intake cone of the SR-71 engine nacelle in the picture below: It is angled so that at Mach 3.2 the cone is symmetrical to the oncoming flow (which gives you a pretty good indication of the angle of attack of the whole plane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VFp5q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VFp5q.jpg&quot; alt=&quot;SR-71 during take-off&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SR-71 during take-off (picture &lt;a href=&quot;http://i.kinja-img.com/gawker-media/image/upload/s--u_uxQr_D--/bptkfxemwykn4tk3r0gy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Not only is the cone angled downward, but also canted in because the flow is pressed sideways by the aircraft's forebody in supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;strong&gt;hypersonic flow&lt;/strong&gt; (Mach &gt; 5) a blunt nose might again be preferable if the nose's materials put an upper limit on aerodynamic heating. A pointed tip will produce an attached shock which will heat the tip to something close to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stagnation_temperature&quot; rel=&quot;nofollow noreferrer&quot;&gt;stagnation temperature&lt;/a&gt; of the flow. A blunt nose, however, will cause a separated shock. This creates more drag and a higher amount of heat overall, but allows to spread this heat over a larger area and dump most of it into the air, &lt;a href=&quot;https://physics.stackexchange.com/questions/555189/why-does-a-bow-shock-produce-less-heating/555355#555355&quot;&gt;producing lower peak loads&lt;/a&gt;. The Space Shuttle had such a blunt nose, since drag minimization is not a priority for a re-entry vehicle.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-05-29T04:16:59.860" LastActivityDate="2020-05-29T04:16:59.860" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="24425" PostTypeId="2" ParentId="24399" CreationDate="2016-01-18T15:03:49.963" Score="2" Body="&lt;p&gt;Speed indicator displays IAS(indicated air speed). It has all this position, installation, instrument errors. When you correct for these errors(using tables from aircraft manual) or air data computer you get calibrated air speed(CAS). &#xA;Pitot position doesn't matter as it's compensated. High speed low pressure or low speed high pressure. Pressure inside the tube will be the same.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8466" LastEditDate="2016-01-19T06:24:10.817" LastActivityDate="2016-01-19T06:24:10.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24427" PostTypeId="1" AcceptedAnswerId="24923" CreationDate="2016-01-18T19:08:33.460" Score="17" ViewCount="3285" Body="&lt;p&gt;While looking at the photos from &lt;a href=&quot;https://aviation.stackexchange.com/questions/24413/what-is-this-open-panel-at-the-rear-of-this-airplane&quot;&gt;this question&lt;/a&gt;&#xA;I noticed a small protrusion from the side of the plane. You can see it in the photo:&lt;br&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/VVN9R.jpg&quot; alt=&quot;787 photo&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and in the diagram from l@aeroalias answer:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/6PTbo.jpg&quot; alt=&quot;787 apu diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the diagram it appears to have something to do with the apu or is fire protection system. There's a shaded line running to it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this object? &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit: It does look like an antenna. I found a diagram of 777 antenna placement &lt;a href=&quot;http://www.avsim.com/topic/451568-glideslope-callout/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;, but it doesn't show anything in that area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/woyvk.jpg&quot; alt=&quot;777 antenna placement&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="15982" LastEditDate="2017-12-21T11:24:08.590" LastActivityDate="2017-12-21T11:24:08.590" Title="What is this device protruding from the rear of this 787?" Tags="&lt;feature-identification&gt;&lt;apu&gt;&lt;sensors&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24428" PostTypeId="1" AcceptedAnswerId="24429" CreationDate="2016-01-18T22:44:33.453" Score="1" ViewCount="443" Body="&lt;p&gt;The weapons systems, including computers etc, in a naval ship can be referred to as the Fire Control System. I'm not sure if FCS would be considered an appropriate acronym for fire control; I'm using to hearing FCS as Flight Control System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a specific aviation term equivalent to Fire Control System? If so, what acronym does it use (if any)?&lt;/p&gt;&#xA;" OwnerUserId="13058" LastEditorUserId="19" LastEditDate="2016-10-17T07:58:46.313" LastActivityDate="2016-10-17T07:58:46.313" Title="What is the aviation term for what the navy calls &quot;fire control system&quot;?" Tags="&lt;military&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24429" PostTypeId="2" ParentId="24428" CreationDate="2016-01-18T22:54:08.800" Score="1" Body="&lt;p&gt;It is still called the (Airborne) Fire Control System; found about it &lt;a href=&quot;https://pe.gatech.edu/courses/basic-airborne-fire-control-systems&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; from a Google search.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well, the acronym for (Airborne) Fire Control System is FCS (As well as Flight Control System) according to &lt;a href=&quot;http://www.militaryacronyms.net/f&quot; rel=&quot;nofollow&quot;&gt;a military acronym website&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12720" LastEditDate="2016-01-19T00:25:03.527" LastActivityDate="2016-01-19T00:25:03.527" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24430" PostTypeId="1" CreationDate="2016-01-18T23:04:18.700" Score="8" ViewCount="2955" Body="&lt;p&gt;The cost of jet fuel during taxiing can be a pain. Concorde in particular had very large fuel expenditure for taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why not put electric motors in at least 2 wheels to drive the plane that way? They would not have to be the most powerful motors in the world---only strong enough to get the plane up to a few miles per hour, or normal taxi speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; I don't think this is a duplicate of &lt;a href=&quot;https://aviation.stackexchange.com/questions/16874/what-is-the-cost-savings-of-using-electronic-motors-to-taxi?lq=1&quot;&gt;this other question&lt;/a&gt;. If anything, the savings cited in the answer of that question seems to imply that my question, asking why it isn't implemented, is actually a pretty good question.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-01-20T09:08:19.947" Title="Why don't large commercial airplanes have electric motors in the wheels?" Tags="&lt;commercial-aviation&gt;&lt;commercial-operations&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ClosedDate="2016-01-19T12:56:06.503" ContentLicense="CC BY-SA 3.0" />
  <row Id="24431" PostTypeId="1" CreationDate="2016-01-19T00:02:33.603" Score="1" ViewCount="1453" Body="&lt;p&gt;Today, many large commercial aircraft have full-fledged entertainment systems, sometimes going as far as putting a personal LED screen in every seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's just consider the costs of this for a moment:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• weight of the devices and their wiring&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• power and waste heat&lt;/p&gt;&#xA;&#xA;&lt;p&gt;• cost of designing and approving the system with the FAA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be more I missed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now let's consider that today, most people (and certainly most people who can afford to fly) have a smart phone of some kind. They will most definitely bring it with them on the flight. And most people will also bring the charger and headphones (or earbuds) with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you can see where this is going. If the airliner wants to provide movies or music, why not just have a jack (USB?) at every seat to plug in your smart phone and get it that way? Or possibly even provide streaming Wifi once in the air (not a true connection to the internet at large, but just as a way to distribute the movies/music). There might still be bandwidth challenges, but surely, &lt;strong&gt;surely&lt;/strong&gt; this is better than a traditional IFE system as it exists today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I missing something?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="7611" LastEditDate="2016-01-19T17:48:00.527" LastActivityDate="2018-05-02T15:06:17.477" Title="Why are there full-fledged entertainment systems on aircraft when today everyone has a smart phone?" Tags="&lt;aircraft-design&gt;&lt;commercial-operations&gt;&lt;inflight-entertainment&gt;" AnswerCount="7" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24432" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T00:20:33.003" Score="5" Body="&lt;p&gt;Today's IFE systems aren't solely about entertainment media. They might also show flight status, let your order meals, offer flight-specific destination information, etc. Now none of this is impossible to do with, say, a local WiFi network and a local web server. However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The typical IFE screen is larger than a smartphone, which is easier for viewing movies&lt;/li&gt;&#xA;&lt;li&gt;You don't have to hold the screen if it's mounted in the seat in front&lt;/li&gt;&#xA;&lt;li&gt;Flight crew would need to be trained in at least basic troubleshooting of passenger devices&lt;/li&gt;&#xA;&lt;li&gt;An alternative would still need to be provided for passengers who did not have a suitable device&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="675" LastActivityDate="2016-01-19T00:20:33.003" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24433" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T00:41:36.580" Score="10" Body="&lt;p&gt;Some airlines (I've personally experienced Delta and United) use PDE (Personal Device Entertainment), where the passenger can download an app prior to their flight and entertainment/flight information can be streamed to their personal devices. You primarily see this on domestic flights, though some international flights do use this (i think more common on older airplanes). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pros:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less weight &amp;amp; cost per seat (no need for screens, power, mounting, remotes, etc.)&lt;/li&gt;&#xA;&lt;li&gt;much cheaper 'upgrade' cost. Instead of upgrading every seat when things are outdated, you update the central server.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Very hard to use the screen while eating, which in my personal experience is one of the peak times where everyone uses entertainment. Your personal device takes up tray table space, and no room for food tray.&lt;/li&gt;&#xA;&lt;li&gt;placing your device on the tray table cranes you neck in a sometimes uncomfortable position. Bad for ergonomics. (especially when passenger in front is reclined.&lt;/li&gt;&#xA;&lt;li&gt;Requires a download BEFORE the flight. In my experience, you're notified of this via email, which i'm sure many people don't read. I've heard countless stories of passengers finding out the hard way...they get on board only to find out you need to download the app, which requires an internet connection...which requires you to pay to access. &lt;/li&gt;&#xA;&lt;li&gt;Supply for customers who don't have tablets/phones.&lt;/li&gt;&#xA;&lt;li&gt;Now you need AC power to each seat to charge said personal devices. What if you're on a 18hr flight. I'm 99% sure most devices cannot last that long streaming video.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Based on the market and the flight, you can see that the carriers choose built-in screens or BYOD. Shorter flights may make more sense to have them bring their own device. On long int'l flights, you're aiming for in-seat IFEs to make the journey more comfortable.&lt;/p&gt;&#xA;" OwnerUserId="9567" LastActivityDate="2016-01-19T00:41:36.580" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="24434" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T02:35:29.327" Score="4" Body="&lt;p&gt;From my perspective using a smartphone/tablet has a few issues.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Usually when traveling I like to be able to communicate, which means my smartphone is off-limits when it comes to playing games/watching movies so I can save my battery in case I have issues at one of my connections or my destination. (Power outlets at airports are like gold, although they are becoming more common). Its a possibility to provide charging for devices in the aircraft but look at the issues associated with that, perhaps somebody plugs in a high load device, or an overheating charger, etc. If the system is approved, it &lt;em&gt;should&lt;/em&gt; be safe, BYOD is giving up that approval process and trusting your fellow passengers that their equipment is in good working order. How many people have had iPhones blow up in their pockets or on chargers?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Even if I could use my smartphone, the issue becomes proping it up on the tray and getting a major neck-ache from looking down at it, along with eye-strain from watching a 5.7&quot; screen (which is huge by todays standards). &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For a tablet, it requires me to also prop it up somehow and stare at it, while the screen is typically larger than the IFE system, its still not ergonomic. I much prefer watching something on the back of the seat where I don't have to look down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;All that being said, I still have to download the movies I want to watch and store them on my device, which I really have better things to do with the space they take up. Its nice being able to choose from a list of channels (like Uniteds DirectTV service) or a good list of movies.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some airlines (I know United does this) have movies available to watch that are not out for purchase or home use yet. Sometimes I get to catch movies in that space where they aren't in the theater anymore but still not out for purchase.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So personally coming from somebody who flies commercially quite a bit, I prefer the IFE over my smartphone/tablet. Its nice being able to lean my head back and watch the video. If the airline ever lets us mount our smart device on the back of the seat ahead of us I may change my opinion, but right now I don't think they would take too kindly to that.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-01-19T02:35:29.327" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24435" PostTypeId="1" AcceptedAnswerId="25087" CreationDate="2016-01-19T03:30:00.427" Score="6" ViewCount="287" Body="&lt;p&gt;Taking a look at the typical large engine of a commercial plane, it looks rather unstreamligned. Nacelle drag is significant IIRC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, then I suddenly remembered these engines produce a large jet of thrust (most of the time). Does this air stream of thrust act as a good shield against nacelle drag? Does it effectively form a bell cone, or half of a seers-haak body, around the rear half of the nacelle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, that would appear to cut the nacelle drag in half.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="7611" LastEditDate="2016-01-19T03:40:55.027" LastActivityDate="2016-02-10T07:09:24.217" Title="Does the stream of engine thrust act as a good drag shield against the nacelle?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;drag&gt;&lt;nacelle&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24436" PostTypeId="2" ParentId="23701" CreationDate="2016-01-19T04:05:17.633" Score="21" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The sound is caused by airflow across holes on the underside of the wings of certain aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Long Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I too have noted the sound phenomenon that you describe. &lt;a href=&quot;https://youtu.be/8g0TWFUDDtE?t=26&quot; rel=&quot;noreferrer&quot;&gt;This video&lt;/a&gt; has a great example between 0:26-52 (link starts playback at 0:26 where the noise starts):&lt;br&gt;&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/8g0TWFUDDtE?start=26&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will readily admit that this answer is mostly just a compilation of what I have learned researching this. Your question intrigued me and I've enjoyed learning about it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I discovered as I started researching this, many others are familiar with the noise as well. &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/321412/&quot; rel=&quot;noreferrer&quot;&gt;This article on Airliners.net&lt;/a&gt; had a lot of discussion about it, starting with a lot of interesting—but ultimately flawed—theories.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, that thread led me to the answer to your question, which is: the sound is caused by the &quot;circular opening used to equalise the pressure in wing fuel tanks&quot;, according to &lt;a href=&quot;http://www.euractiv.com/sections/aviation/small-beautiful-how-tiny-device-cuts-aircraft-noise-303505&quot; rel=&quot;noreferrer&quot;&gt;Euractiv.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://http://www.airportwatch.org.uk/2014/11/lufthansa-retrofitting-a320-family-with-simple-inexpensive-noise-reducing-device-to-stop-the-airbus-whine/&quot; rel=&quot;noreferrer&quot;&gt;This article on AirportWatch&lt;/a&gt; further explains: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Airbus 320 series of aircraft, [...] have been known for many years&#xA;  [...] to have a particularly irritating high pitched&#xA;  whine. This is caused by air rushing across the under-surface of the&#xA;  wing, where there are Fuel Over Pressure Protector (FOPP) cavities.&#xA;  This generates noise, in the same way as blowing air over the mouth of&#xA;  a bottle. Every A320 series aircraft emits a signature howling noise&#xA;  while approaching to land. It is heard most when the plane is&#xA;  travelling at around 160 knots, and the frequency is around 500-600Hz,&#xA;  which is close to peak sensitivity of the  human ear.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That being said, there is apparently a fix to that problem, as both the aforementioned links describe. As &lt;a href=&quot;http://www.euractiv.com/sections/aviation/small-beautiful-how-tiny-device-cuts-aircraft-noise-303505&quot; rel=&quot;noreferrer&quot;&gt;Euractiv.com&lt;/a&gt; explains, the fix is a vortex generator:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a 5-cm triangular piece of aluminium sheet metal upstream of the two&#xA;  vents on each wing, in order to divert the air flow and stop the&#xA;  whistle. A decade of research went into the vortex generator, which&#xA;  stems from efforts to mask a similar whistle produced when air blows&#xA;  over the gun ports of warplanes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This image shows both the FOPP hole, and the VG that softens the sound:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Gu0fM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gu0fM.jpg&quot; alt=&quot;A320 FOPP and VG*Image Courtesy of Lufthansa*&quot;&gt;&lt;/a&gt;[Image Courtesy of Lufthansa]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Read the articles linked, interesting stuff therein!&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-19T12:42:10.397" LastActivityDate="2016-01-19T12:42:10.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24437" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T04:05:38.937" Score="13" Body="&lt;p&gt;Here are some points to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The screen size is a huge part of the experience. People with smartphones mostly still view content on a large regular screen when they are home or at a hotel etc. Hence, given a choice a passenger is always going to prefer the larger screen you can pack into the seat back than the relatively smaller smartphone display. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you can be &lt;strong&gt;sure&lt;/strong&gt; every seat has an IFE screen you can use it for other purposes like mandatory safety announcements &amp;amp; videos. Unless  you can be sure there's no seat without a smartphone owner depending on them for such messages is hard&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you have an existing aircraft the cost &amp;amp; effort to modify it &amp;amp; recertify the changed config. isn't worth it&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Smartphones have only become ubiquitous in the last 5 years. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Average fleet age is much more than that. A typical aircraft you fly on might have been built 10, 15 or even 20 years before today. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Manufacturing date is not as important as the design date: If you are flying even in a 5 year old aircraft but the design was made 20 years ago there's no chance the designer could even forsee the smartphone revolution so he put in the IFE. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;New designs you can expect modifications e.g. Many recent aircraft have a local USB port you mention &amp;amp; allow the passenger to plug in his device &amp;amp; view his own movies or listen to his own music on the IFE screen. &lt;a href=&quot;http://www.turkishairlines.com/en-int/travel-information/frequently-asked-questions/on-board/in-flight-entertainment&quot;&gt;http://www.turkishairlines.com/en-int/travel-information/frequently-asked-questions/on-board/in-flight-entertainment&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Connections enabling passengers to listen to, or watch on their&#xA;  individual screens, content on their personal iPods or USB devices are&#xA;  available on B777 and some of our A330 aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The power and waste heat tradeoff of smartphones vs dedicated IFE isn't clear: If you encourage IFE via smartphones you would need to provide charging capacity for simultaneous plug in of hundreds of phones. The electrical resources for that aren't  insignificant. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The devil you know is better than the one you don't: Dedicated IFE is tested &amp;amp; certified with well known characteristics. Having hundreds of unknown chargers plugged in &amp;amp; batteries charging adds other variables to the game. You'd also have to support multiple OSs, screen sizes etc. on the software side.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2016-01-19T11:36:17.807" LastActivityDate="2016-01-19T11:36:17.807" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24438" PostTypeId="2" ParentId="12730" CreationDate="2016-01-19T04:17:40.767" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.dailymail.co.uk/travel/travel_news/article-3315070/Emirates-new-Airbus-A380-capacity-615-passengers.html&quot; rel=&quot;nofollow&quot;&gt;The Daily Mail&lt;/a&gt; and &lt;a href=&quot;http://www.seatguru.com/airlines/Emirates_Airlines/Emirates_Airlines_Airbus_A380_Two_Class.php&quot; rel=&quot;nofollow&quot;&gt;Seat Guru&lt;/a&gt; both show Emirates having a two class version with 615 seats total, 557 economy. And, while &lt;a href=&quot;http://www.emirates.com/english/flying/our_fleet/emirates_a380/emirates_a380_specifications.aspx&quot; rel=&quot;nofollow&quot;&gt;Emirates&lt;/a&gt; only shows three class versions if you actually look up the route mentioned by the first link &lt;a href=&quot;http://www.emirates.com/english/flying/our_fleet/emirates_a380/emirates_schedule/dubai-copenhagen.aspx&quot; rel=&quot;nofollow&quot;&gt;(Dubai - Copenhagen)&lt;/a&gt; you will see it only has Business, Economy. Clicking on the &quot;View services&quot; link will also show the First class missing. So, despite the Daily Mail being a rag and Seatguru not being 100% reliable to say the least I must say the evidence strong for this configuration.&lt;/p&gt;&#xA;" OwnerUserId="11524" LastEditorUserId="5517" LastEditDate="2016-01-19T16:47:58.873" LastActivityDate="2016-01-19T16:47:58.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24439" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T04:40:26.470" Score="4" Body="&lt;p&gt;The real answer is in @curious_cat 's answer but it needs to be emphasized:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;it's the safety videos.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC121-24C.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Advisory Circular 121-24C&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pretakeoff oral briefing may be given by&#xA;  audiotape or videotape means. This method of passenger briefing should be considered when&#xA;  the aircraft is equipped with the necessary videotape and sound equipment. The advantage of&#xA;  audiotape or videotape presentations is the assurance that a complete briefing is given, that the&#xA;  diction is good, and that an overall high quality briefing is maintained. Tape presentations also&#xA;  lend themselves very well to a multilingual presentation. In addition, a videotape presentation&#xA;  can include “signing” for the deaf and other visual presentations, which may be more meaningful&#xA;  to passengers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There you have it. Showing a videotaped safety demo ensures the FAA won't fine you to oblivion because some passenger filed a complaint that the demo was not satisfactory. Believe me, airlines do not want to cross the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Advertisment and movies are gravy. It just means some of the costs you can chalk up to marketing. Good for you.&lt;/p&gt;&#xA;" OwnerUserId="11524" LastEditorUserId="11524" LastEditDate="2016-01-19T04:48:44.370" LastActivityDate="2016-01-19T04:48:44.370" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24440" PostTypeId="2" ParentId="24431" CreationDate="2016-01-19T06:10:52.557" Score="2" Body="&lt;p&gt;Consider an entirely different perspective - airlines are forever trying to differentiate their products and the in-flight entertainment is one area that airlines tend to compete or display their edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many airlines specifically advertise the features of their entertainment systems as part of the perks of flying the airline - as technology becomes more ubiquitous and embedded, I can only see more innovation in this area - rather than the reverse of removing the option completely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Practically speaking; there are some other concerns with the BYOD concept:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You cannot get airline-customized information on your personal device - for example, the outside camera views on Emirate aircraft or the cockpit radio transmissions that you can tune into on some United flights. I am sure it would be possible to do this, but the hassle of supporting a large sea of various devices is not worth it in the long term.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As mentioned by others, there is a safety concern here. Any equipment has to be certified and it may be difficult to get all cellphone manufacturers to agree to a standard to be compatible with all the various aircraft and seat configurations. In addition they are required to provide a uniform experience when safety videos are shown.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Personal technology moves at a faster pace and is subject to different controls and regulations than aircraft and airlines. It would be very expensive for airlines to make sure the seats on their aircraft are compatible with all the various types, configurations, screen sizes, power requirements for personal entertainment devices.  Aircraft also have a longer service life than personal electronic devices.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Although airlines are starting to integrate personal devices into their infotainment systems - those screens are there to stay for the long term and will only get more integral to the flight experience.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-01-19T06:10:52.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24441" PostTypeId="1" AcceptedAnswerId="24446" CreationDate="2016-01-19T06:20:33.337" Score="37" ViewCount="27656" Body="&lt;p&gt;In most jet fighters, the cockpit is a glass dome and the pilots are exposed directly to the sun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, they are wearing flight suits and full face helmets (most of the time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can only imagine that with no respite from the sun, the cockpit must heat up very quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What measures are there for climate control or pilot comfort?&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="22550" LastEditDate="2019-01-02T15:24:59.033" LastActivityDate="2020-01-06T17:40:00.687" Title="Do jet fighters have air conditioning systems?" Tags="&lt;fighter&gt;&lt;jet&gt;&lt;cockpit&gt;&lt;air-conditioning&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24442" PostTypeId="2" ParentId="24441" CreationDate="2016-01-19T06:34:28.133" Score="14" Body="&lt;p&gt;From second-hand experience (I can say I am really close with a Tornado pilot), the Tornado has a compressor stage airbleed that directs some cold air directly in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He would describe it as a direct blast of air in the middle of your stomach, without any possibility to direct it elsewhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question, then, we can say that at least some military aircraft do have an air conditioning system, even if it is probably not the best system ever.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Searching a bit further, &lt;a href=&quot;https://books.google.de/books?id=3shgcJXesN0C&amp;amp;pg=PA132&amp;amp;lpg=PA132&amp;amp;dq=panavia%20tornado%20air%20conditioning%20system&quot; rel=&quot;nofollow noreferrer&quot;&gt;this book&lt;/a&gt; mentions a &quot;Normalair Garrett system&quot;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/gbtkK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gbtkK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;that, from a quick search, turns out to be &lt;a href=&quot;https://en.wikipedia.org/wiki/Normalair&quot; rel=&quot;nofollow noreferrer&quot;&gt;the name&lt;/a&gt; of a british life-supporting system manufacturer, I would then suspect that this system is not limited to a few military aircraft, but rather to be quite widespread.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="7532" LastEditDate="2020-01-06T17:40:00.687" LastActivityDate="2020-01-06T17:40:00.687" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24443" PostTypeId="2" ParentId="2354" CreationDate="2016-01-19T09:16:11.000" Score="4" Body="&lt;p&gt;Rather than painted white, Boeing documents the option of keeping a fleet &quot;polished&quot; raw aluminium. Polished is more efficient to fly, but it requires more maintenance, buffing the entire plane multiple times a year, whereas painted aeroplanes require maintenance every 4 years... Here is an article with silver colored versus painted aeroplanes by Boeing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Polished vs Painted by Boeing&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;here are pictures of &lt;a href=&quot;https://www.google.fr/search?q=polished%20airplane&amp;amp;num=100&amp;amp;espv=2&amp;amp;source=lnms&amp;amp;tbm=isch&quot; rel=&quot;nofollow noreferrer&quot;&gt;polished aeroplanes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are various fan pages that talk about polishing planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military planes are often painted different from civilian ones and with regard to camouflage, grey, cammo, blue for sea, it's mostly fleet themes and standards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RXUwC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RXUwC.jpg&quot; alt=&quot;jal cargo2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paint on a large plane adds something like 230 kilos, 475 lbs for a B777-200 airliner. Amercian airlines was the last to have silver aeroplanes: &lt;a href=&quot;http://www.airlinepilotchatter.com/2013/01/new-american-airlines-livery-to-paint.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.airlinepilotchatter.com/2013/01/new-american-airlines-livery-to-paint.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8098" LastEditorUserId="8098" LastEditDate="2016-01-19T09:38:39.213" LastActivityDate="2016-01-19T09:38:39.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24444" PostTypeId="2" ParentId="24430" CreationDate="2016-01-19T09:43:52.830" Score="8" Body="&lt;p&gt;In fact, this is currently on test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This test is conducted by Airbus, Safran and Honeywell for the Airbus 320 familly on this aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lTFj4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lTFj4.jpg&quot; alt=&quot;EGTS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine is installed on the wheels of the main landing gear&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SClF7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SClF7.jpg&quot; alt=&quot;wheel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you might know it take long time and lot of money to certified a system in aeronautics, this is why it's not in use yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I other hand, you need to run engine in idle for about 5 minutes in order to warm up the engine and stabilise systems (hydraulics, gyroscopes, etc)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find more here : &lt;a href=&quot;http://www.greentaxiing.com/&quot; rel=&quot;noreferrer&quot;&gt;http://www.greentaxiing.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 1 : edit to add @Ben elements&lt;/p&gt;&#xA;" OwnerUserId="3039" LastEditorUserId="3039" LastEditDate="2016-01-20T09:08:19.947" LastActivityDate="2016-01-20T09:08:19.947" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24445" PostTypeId="2" ParentId="24430" CreationDate="2016-01-19T12:14:58.217" Score="6" Body="&lt;p&gt;As Kromen points out, such a system is in development. There are just two main impediments:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The not-insignificant costs of design, certification, installation and operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Jet engines can't just be turned on as the aircraft lines up on the runway. The startup sequence itself can take a few minutes, and then they need to be running at close to idle for up to about 5 minutes to allow all of the aircraft systems (hydraulics, gyroscopes, etc) to stabilise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These aren't insurmountable obstacles, and the system should have great benefits at busy airports with long taxi times. But this helps explain why it hasn't exactly been a top priority over the years. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-01-19T12:14:58.217" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24446" PostTypeId="2" ParentId="24441" CreationDate="2016-01-19T12:31:45.123" Score="37" Body="&lt;p&gt;Yes. Fighter aircraft have air conditioning systems. In general, they are called as Environmental Conditioning Systems (ECS). Their primary functions (as far as cockpit goes) include,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Cockpit Pressurization&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Heating/Cooling/air-conditioning&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Windshield anti-fog/anti-ice&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The systems usually use conditioned engine bleed air or this purpose. The cockpit air conditioning is usually managed by the pilot. For example, in case of F-15, the following system is available:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5vAL7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5vAL7.jpg&quot; alt=&quot;F-15 ECS&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from f-15e.info&lt;/p&gt;&#xA;&lt;p&gt;with the available controls listed as,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TEMP switch: A three-way switch to manage cockpit temperature. When AUTO, cockpit temperature is automatically maintained at the temperature selected on the TEMP knob. When MANUAL, cockpit temperature may be changed with the knob, but not maitained automatically. When OFF, it shuts down off ECS air.&lt;/p&gt;&#xA;&lt;p&gt;TEMP knob: A rotary knob to set the cockpit temperature.&lt;/p&gt;&#xA;&lt;p&gt;FLOW switch: A three-way switch to select air flow. MIN, MAX and NORM settings are available for minimum/maximum/normal air flow, respectively.&lt;/p&gt;&#xA;&lt;p&gt;FLOW knob: A four-position knob to set the air source. When BOTH, bleed air is supplied from both engines. When L ENG or R ENG, bleed air is supplied from the left/right engine only. When OFF, no bleed air is supplied.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The following image shows the other controls associated with ECS.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aA9T1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aA9T1.jpg&quot; alt=&quot;F-15 ECS&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from f-15e.info&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-01-06T15:34:06.950" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24447" PostTypeId="1" CreationDate="2016-01-19T14:33:59.923" Score="9" ViewCount="710" Body="&lt;p&gt;The background story is &lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper&quot; rel=&quot;nofollow noreferrer&quot;&gt;a hijacking that happened 1971&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hijacker, referred to as D.B. Cooper, jumped from a Boeing 727 using the aft airstair. He knew in what air corridor he was (Victor 23, heading south to Mexico from Seattle) and the time.  The mount St. Helens (8,365'), was about 10 miles north to him. Portland was 20 miles south. He had however zero visibility of the ground. It was nighttime and raining heavily. I suppose he would not see any lights from Ariel (WA), 10 miles north to his position, and which has a population of about 700 nowadays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With what precision could D.B. Cooper know where he would fall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is another related question, but not a duplicate here: &lt;a href=&quot;https://aviation.stackexchange.com/questions/24449/would-a-90-kg-object-jettisoned-from-an-aircraft-create-a-detectable-movement&quot;&gt;Would a 90 kg object jettisoned from an aircraft create a detectable movement?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="914" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2017-10-09T07:11:26.447" Title="Could D.B. Cooper know where he was landing, when he parachuted?" Tags="&lt;navigation&gt;&lt;parachute&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24449" PostTypeId="1" CreationDate="2016-01-19T16:19:04.880" Score="7" ViewCount="1310" Body="&lt;p&gt;I was reading the description of an old hijacking which has this snippet of interesting information:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After takeoff Cooper told Mucklow to join the rest of the crew in the&#xA;  cockpit and remain there with the door closed..... At&#xA;  approximately 8:00 pm a warning light flashed in the cockpit,&#xA;  indicating that the aft airstair apparatus had been activated.... The crew soon noticed a subjective change of air&#xA;  pressure, indicating that the aft door was open. At approximately 8:13&#xA;  pm &lt;strong&gt;the aircraft's tail section sustained a sudden upward movement,&lt;/strong&gt;&#xA;  significant enough to require trimming to bring the plane back to&#xA;  level flight. At approximately 10:15 pm Scott and Rataczak landed&#xA;  the 727, with the aft airstair still deployed, at Reno Airport....an armed search quickly confirmed that he&#xA;  was gone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Would a 90 kg man jumping off the aft stairs of a B-727 in flight create a detectable &quot;sudden upward moment&quot;. Not just a slight one but &quot;significant enough to require re-trimming&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doesn't sound like a fluke or the product of a vivid imagination because we further know that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An experimental re-creation was conducted using the same aircraft&#xA;  hijacked by Cooper in the same flight configuration, piloted by Scott.&#xA;  FBI agents, pushing a 200-pound (91 kg) sled out of the open airstair,&#xA;  &lt;strong&gt;were able to reproduce the upward motion of the tail section described&lt;/strong&gt;&#xA;  by the flight crew at 8:13 pm.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The full story is here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/D._B._Cooper&quot;&gt;https://en.wikipedia.org/wiki/D._B._Cooper&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm estimating the mass of a fully-fueled B-727 as about 60,000 kg. A detectable perturbation by a 90 kg ejected body sounded a tad unlikely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I'd love to see a more accurate calculation. I suppose the center of gravity and the long lever arm for the aft stairs location will matter? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PS.&lt;/strong&gt; It seems far more plausible to me that the movement detected was actually due to the aerodynamic forces on aft stairs and not the effect of the ejected 90 kg mass. The only reason I was rejecting this explanation was that the timing seems off if we are to believe the flight crew report:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They seem to have detected two events: A pressure change and later this reported sudden movement. So the movement does not seem correlated in time with the aft stair deployment. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2016-01-20T05:08:56.963" LastActivityDate="2016-01-20T05:08:56.963" Title="Would a 90 kg object jettisoned from an aircraft create a detectable movement?" Tags="&lt;aerodynamics&gt;&lt;boeing&gt;&lt;theory&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24450" PostTypeId="2" ParentId="24449" CreationDate="2016-01-19T16:30:02.560" Score="9" Body="&lt;p&gt;I would suggest that the aft stairs acted as a control surface lifting the tail. Perhaps they will not extend fully against the slipstream until a weight of 90 kg is applied to the end...&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-01-19T16:30:02.560" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24451" PostTypeId="2" ParentId="24447" CreationDate="2016-01-19T17:09:51.640" Score="5" Body="&lt;p&gt;We have no idea how much he did know, but it's possible he had a basic idea. The fact he came up with the plan at all suggests some kind of aviation background (the air stair, for example, wouldn't occur to many people): so we can probably assume at least some basic navigation ability, especially with how thought out the plan appears to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He knew where the aircraft was starting from. He knew the airspeed it would travel at (100 knots, just above stall speed), which would give him a rough idea of how far it had travelled&amp;nbsp;&amp;ndash; particularly if he had information about the wind at that level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;Distance = Time x Speed&lt;/code&gt;... so all we're missing is the Time. If he knows how long they've been travelling, that's sufficient to allow him to have a reasonable idea of where they are along a known track, particularly if he carried a compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's hard to be sure without the precise weather conditions available, but even in rain then as long as you're below the cloud layer, I wouldn't be surprised if Cooper could see the lights of either Portland or, more likely (considering the angle) Ariel: towns are pretty visible from the air. For example this photo is London from 10,000ft. Admittedly London is quite a lot bigger than Ariel, and the weather is clear, but considering the &quot;closer&quot; areas of the picture are a couple of miles, and the &quot;distant&quot; areas are more like 20 miles away, it's fairly easy to see how even a small town can be quite visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UMHY2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UMHY2.jpg&quot; alt=&quot;London from 10,000ft&quot;&gt;&lt;/a&gt;&#xA;(source: &lt;a href=&quot;https://www.flickr.com/photos/andygocher/12836895204&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.flickr.com/photos/andygocher/12836895204&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that at 100 knots ground speed the aircraft is travelling at ~2 miles per minute across the ground. I can't find any wind data, but considering the 8:13 jump time was only approximate, it's more than possible that he saw the town below and a mile or two below and behind the aircraft, took a minute or so to prepare, and then jumped when 4-5 miles from the town.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He probably didn't know precisely where he was, but there's a reasonable chance that he saw a town below and that was sufficient for him to attempt the jump. He had the equivalent of over a million dollars in his pocket, he only had to find a town and get on a train in order to escape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We also have no idea whether he had a chart or similar in his bag, nor whether there was any potential visibility of Mount St Helens (possible, considering the 1/4 moon that night). It's unlikely at 10 miles, but they'd passed it earlier and he may have used it as a point of reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short: he probably had a rough idea of the region (to within 50 miles or so) and quite possibly had just seen a small town.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did he know what town it was? Probably not, but he likely didn't care either: he had enough money that as long as he survived the jump and walk into the town, it probably didn't matter what the town was.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="946" LastEditDate="2017-10-08T19:31:03.683" LastActivityDate="2017-10-08T19:31:03.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24452" PostTypeId="2" ParentId="24449" CreationDate="2016-01-19T17:22:08.990" Score="11" Body="&lt;h2&gt;Yes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It's not just weight, it's also aerodynamics. First let's assume that the aircraft was trimmed slightly nose-heavy (no passengers), therefore it's trimmed slightly &quot;tail down&quot; anyway&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the stair was first opened, it would have been held partially closed by the airflow under the fuselage - it's not heavy enough alone to extend fully against a 100 knot wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was then a two-part change from Cooper leaving the aircraft - one of him walking down the stair, pushing it into the airflow and acting much like the elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When he then jumped, the loss of his weight at the very back of the aircraft, along with a presumed &quot;push&quot; against the door, pushing it further into the airstream, would have simultaneously jolted the tail up, then reduced the weight at the very back of the tail &quot;lever&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;90kg doesn't sound like very much, but when it's at the very, very back of quite a long lever, and when combined with the airstair, the results seem perfectly reasonable and, indeed, were proven by the FBI.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-01-19T17:22:08.990" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24455" PostTypeId="1" CreationDate="2016-01-19T18:56:07.870" Score="7" ViewCount="7495" Body="&lt;p&gt;I am interested in flying wings and a couple of weeks ago I started researching them. I found &lt;a href=&quot;http://www.mh-aerotools.de/airfoils/flywing1.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;mh-aerotools.de&lt;/a&gt; website and think it's a great source. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The website stated that flying wings need twist to stabilize, but I don't know how to do this or even is it required at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is a twist needed and if so how do I to calculate it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I chose airfoil EH 1.0-9.0 for this purpose.&lt;/p&gt;&#xA;" OwnerUserId="13066" LastEditorUserId="23223" LastEditDate="2019-09-10T07:20:55.503" LastActivityDate="2019-09-10T07:20:55.503" Title="What is the way to calculate the required twist of a flying wing?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;flying-wing&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24456" PostTypeId="1" AcceptedAnswerId="24459" CreationDate="2016-01-19T20:08:59.087" Score="7" ViewCount="804" Body="&lt;p&gt;Twitter account for Flightradar24 has reported twice in past 24 hours about two different British Airways flights that has diverted their original route &quot;&lt;em&gt;due to the needs of a passenger&lt;/em&gt;&quot; (&lt;a href=&quot;https://twitter.com/flightradar24/status/689298295479529472&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://twitter.com/flightradar24/status/689264852238479361&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exactly does it mean? Is it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a passenger requesting to land on other airport, because he forgot his wallet?&lt;/li&gt;&#xA;&lt;li&gt;operational decision to put more passengers on-board empty plane?&lt;/li&gt;&#xA;&lt;li&gt;something else?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="12220" LastEditDate="2017-09-26T01:32:32.113" LastActivityDate="2017-09-26T01:32:32.113" Title="What exactly does it mean, that plane has diverted due to the needs of a passenger?" Tags="&lt;terminology&gt;" AnswerCount="3" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24457" PostTypeId="2" ParentId="24456" CreationDate="2016-01-19T20:12:23.367" Score="8" Body="&lt;p&gt;According to FR24's comment on the post, they use that term when they do not know the exact nature of the incident. However, it is most likely a medical emergency.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-19T20:12:23.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24458" PostTypeId="2" ParentId="21112" CreationDate="2016-01-19T20:26:43.660" Score="0" Body="&lt;p&gt;The reason a Glider can stay up is for the simple reason that the pilot is there to read the weather and the terrain, and to coax the aircraft along areas and lines of lift. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-19T20:26:43.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24459" PostTypeId="2" ParentId="24456" CreationDate="2016-01-19T20:35:23.203" Score="18" Body="&lt;p&gt;The only passenger needs that would result in a non-scheduled landing would be a medical emergency or acts/threats of violence of the level that prompt removal of the passenger is needed (with law enforcement coordination).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A passenger forgetting his wallet would not result in a diversion.  An aircraft deviation to enplane more passengers and proceeding to the scheduled destination would be a highly unusual situation and would not be for passenger needs, it would be for operational needs.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-19T20:35:23.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24460" PostTypeId="1" CreationDate="2016-01-19T23:10:24.220" Score="4" ViewCount="223" Body="&lt;p&gt;What's the approximate price for all the food and beverage preparation &amp;amp; storage equipment on the A350? If you don't know the answer for the A350, I'm interested in hearing knowledgeable estimates with a 90% confidence interval range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking for a research project I'm doing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In response to the critique that the question is too broad: Food and beverage storage and preparation equipment on large wide-bodies is supplied by just 1 or 2 global suppliers. I wouldn't expect the price to be different by geography since it's all typically denominated in USD. But, if it makes a difference, let's say we are talking about the US market.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an example, I believe I know the following from prior research:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the galleys in each A350 cost about \$1-1.3 million USD per A350 aircraft,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the business class seats likely cost about \$2.6 million in each A350 assuming \$70-80 thousand USD per business class seat multiplied by an estimated 35 business class seats for airlines that choose a 2-class configuration of the A350.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the oxygen systems in each A350 is roughly \$100-150 thousand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming a 2-class configuration of the most popular version of the A350, what's the approximate total value of all the food and beverage storage and preparation equipment?  If there are important distinctions or configurations I'm not clarifying, I'd ask you to assume the configuration that is most common since that would be most reflective of the overall market.&lt;/p&gt;&#xA;" OwnerUserId="13072" LastEditorUserId="62" LastEditDate="2016-01-20T18:21:20.827" LastActivityDate="2016-01-20T20:09:14.197" Title="Approximate Cost of Food &amp; Beverage Preparation &amp; Storage Equipment on A350" Tags="&lt;airline-operations&gt;&lt;airbus-a350&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2016-04-20T18:14:49.320" ContentLicense="CC BY-SA 3.0" />
  <row Id="24461" PostTypeId="1" CreationDate="2016-01-19T23:35:22.843" Score="9" ViewCount="738" Body="&lt;p&gt;With an FAA Section 333 Exemption, they will permit you to fly up to 400' above ground level. But they also restrict you to flying at least 500' away from people and vehicles unless you have their permission. You can't get permission from every vehicle driver that happens to be passing by. Does this effectively mean that there is absolutely no way to fly over a public roadway, or is there another exception or reasoning to be able to do this?&lt;/p&gt;&#xA;" OwnerUserId="13073" LastEditorUserId="12720" LastEditDate="2016-01-20T01:09:34.437" LastActivityDate="2016-01-20T01:38:55.397" Title="Is there a way to fly an UAV over a roadway?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24462" PostTypeId="2" ParentId="24455" CreationDate="2016-01-19T23:50:09.430" Score="0" Body="&lt;p&gt;The wing twist (washout for swept back wings) helps in speed and stall stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider a &lt;em&gt;normal&lt;/em&gt; aircraft- i.e. the ones that have a tail (horizontal stabilizer)- in this case, the wing produces an upward force, while the tail produces a downward force. Here, as the nose goes down, the speed increases, and the lift produced by the main wing means that the nose pitches up again. The opposite happens when it the nose goes up- the speed drops and as the airspeed decreases, the nose drops (as lift is now lesser). As the wing is at a higher incidence compared to the tail, it stalls first, and the stabilizer (which is still producing lift) pitches the nose down, bringing it out of the stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As there is no horizontal stabilizer in case of tailless aircraft, these effects have to be built in into the wing itself. One way to do so is to have a washout- having a swept wing with the outboard area at an incidence lesser than the inboard (root) section. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, as the speed increases, the front portion of the wing (near the root in swept wing) produces more lift as the speed increases, pitching up the nose. The opposite happens as the speed decreases- the nose pitches down as the lift is decreases with airspeed loss. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft approaches stall, the inboard section (at a higher angle of attack) stalls first, while the outboard section, which is at the rear (due to the wing sweep) causes the nose to pitch down, causing the aircraft to come out of stall. The added advantage is that the control surfaces are still functional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same effect can be obtained by using a reflex airfoil and an unswept wing, with the reflexed portion acting as the tail.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-19T23:50:09.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24463" PostTypeId="1" AcceptedAnswerId="24466" CreationDate="2016-01-20T00:04:12.723" Score="6" ViewCount="1051" Body="&lt;p&gt;Normally, two departures are required to be separated by a minimum amount of time depending on the weight class of the aircraft.  However, I was wondering if someone could explain why departure-departure separations are not assigned by a minimum distance instead of a minimum time.  It seems that using a minimum time is potentially more inefficient, especially if the time to reach a safe distance for wake effect purposes is considerably less than the minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a related question, are there any research projects or articles that someone can point to that talk more about this subject?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="4422" LastEditorUserId="167" LastEditDate="2016-01-28T03:17:47.310" LastActivityDate="2016-01-28T03:17:47.310" Title="Why aren't departures separated by minimum distance rather than minimum time?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;wake-turbulence&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24465" PostTypeId="2" ParentId="24461" CreationDate="2016-01-20T01:38:55.397" Score="5" Body="&lt;p&gt;For certain operations the FAA does grant waivers to &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/farsbysectlookup/91.119&quot; rel=&quot;noreferrer&quot;&gt;14 CFR § 91.119(b)&lt;/a&gt; and/or &lt;a href=&quot;http://rgl.faa.gov/regulatory_and_guidance_library/rgfar.nsf/farsbysectlookup/91.119&quot; rel=&quot;noreferrer&quot;&gt;(c)&lt;/a&gt;. These waivers are generally granted for the purpose of allowing pipeline or powerline patrol, aerial survey, or for other operations that are in the public interest. The waivers are also generally granted to the operators of certified or restricted category aircraft, not UAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you represent an operation for which a waiver would be in the public's interest and can demonstrate that the operation would be conducted safely, you might qualify for a waiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, even for that waiver, you have to demonstrate strong evidence to gain a minimum distance of less than 500 feet:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v03%20tech%20admin/chapter%2007/03_007_001.pdf&quot; rel=&quot;noreferrer&quot;&gt;3-185 A.&lt;/a&gt; Unless it is necessary to&#xA;  safeguard human life or it can be determined to be in the public interest and contributing to the public health, welfare, and safety, the 500-foot minimum separation distance from persons on the surface shall not be waived.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that 14 CFR § 91.119(a) and (d) are never to be waived.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://fsims.faa.gov/wdocs/8900.1/v03%20tech%20admin/chapter%2007/03_007_001.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt; for more information on the above discussed waiver.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, all that being said, I don't know if the above example of a waiver apples directly to your question or not; perhaps 91.119 is not the regulation that you were concerned about. Regardless, that waiver is an example of what can be worked out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current UAS issue is uncharted water for the FAA; there may or may not be precedent for an operation or exemption. Bottom line, if you have a really good reason to do the operation you want to do, you might be able to work it out with the FAA. Otherwise, you will have to stick to the rules as they are.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-01-20T01:38:55.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24466" PostTypeId="2" ParentId="24463" CreationDate="2016-01-20T01:39:51.813" Score="4" Body="&lt;p&gt;For the FAA(all my answers can be looked up, and expanded upon in FAA Order &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;7110.65W, Chapter 3&lt;/a&gt; mainly, but I'll try to keep it short), most departures from the same runway use distance for separation. The standard is the lead aircraft is clear of the runway, but most of the time can be shorter under most circumstances. The only times it becomes time based, if it's wake turbulence related, or various conditions of non-radar separation needing to be applied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general for runways, aircraft are broken into 3 categories for separation(excluding weight class, which add wake turbulence time if necessary). Category I aircraft are light single engine propeller driven aircraft weighing less than 12,500 lbs (and helicopters). Category II aircraft are light twin engine propeller driven aircraft weighing less than 12,500 lbs. Category III is everything else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll mainly discuss same runway departures, since there's many considerations and it gets complex, and the FAA Order 7110.65 does a fairly good job of depicting and showing this separation standard. For the same runway when both aircraft aircraft departing are category I, the min distance between them is 3,000 feet and airborne. This means that the first aircraft has to be 3,000 feet down the runway and airborne, before the next aircraft starts it's takeoff roll. If the trailing aircraft is a Category II and the first aircraft is a Category I or II,  the distance increases to a separation of 4,500 feet between aircraft. If either aircraft is a Category III aircraft, it's 6,000 feet and airborne required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if both aircraft are IFR, there needs to be IFR separation insured after the runway separation. In most environments the minimum radar separation is 3 nautical miles between aircraft. Now, between jets, the runway separation of 6,000 feet and airborne, will often be right at 3nm between aircraft(due to the speed differential mainly). Other options include turning one aircraft off the path of the other by at least 15 degrees and have them diverge apart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wake turbulence is one of the few areas that time is applied. If a heavy(300,000 lbs or greater) is departing in front of anything else, the next aircraft can't start their departure roll for 2 minutes when both are departing from the same intersection on the runway, and 3 minutes if departing the runway from different intersections. And a Super(A380/AN225) I believe are 3 minutes, when departing the same intersection, but I've never worked them in the tower. There are a few other times when time is used, intersections, opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For arrivals, all except non-radar separation is distance based.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="2785" LastEditDate="2016-01-28T01:23:39.873" LastActivityDate="2016-01-28T01:23:39.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24467" PostTypeId="1" CreationDate="2016-01-20T02:29:09.200" Score="3" ViewCount="779" Body="&lt;p&gt;In the newest large commercial jets, composite materials seem to be all the rage. The first thing I wanted to know is why composites were chosen instead of titanium? If I'm not mistaken, titanium has even more specific tensile strength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's also be clear about what exactly composites are. &quot;Composite&quot; just means a mix of two or more materials, and in aerospace, it is predominantly autoclave-cured carbon-epoxy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, it would be good to understand the criteria that govern any choice among titanium, composites, and aluminum. Specifically, which areas of the plane are candidates for an advanced material? and why? What factors dictate the decision?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3504" LastEditDate="2016-01-20T13:45:27.813" LastActivityDate="2019-08-14T07:49:36.517" Title="What are the criteria that govern the choice between titanium, composites, and more common materials, like aluminum?" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;&lt;aerospace-materials&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24468" PostTypeId="1" AcceptedAnswerId="24469" CreationDate="2016-01-20T03:05:25.513" Score="14" ViewCount="15035" Body="&lt;p&gt;Suppose I am not planning to be a career A&amp;amp;P mechanics, but would like to get some hands-on skills for airplane maintenance, for reasons of both cost and hobby. Say my basic goal is to perform tasks from as simple as tire replacement, instrument replacement to avionics installation and troubleshooting. My goals may be progressive. The aircraft for maintenance is self-owned or owned by share. The ownership and operation of the aircraft is within US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I work on my own airplane? Since I'm not certified for mechanics work would it be OK that a certified A&amp;amp;P endorse my work is standard-compliant?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="62" LastEditDate="2016-01-21T14:08:25.250" LastActivityDate="2019-03-27T17:46:37.753" Title="Can I work on my own airplane without formal mechanic's training?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24469" PostTypeId="2" ParentId="24468" CreationDate="2016-01-20T03:34:24.570" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/part-43/appendix-A&quot;&gt;FAR Part 43&lt;/a&gt; contains the information of what you can and cannot do to an aircraft and what requirements you must have. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are a certificated &lt;strong&gt;Private Pilot&lt;/strong&gt; (as in not a sport pilot), there are quite a few things you can do to &lt;strong&gt;an aircraft you own, that is not used for commercial purposes&lt;/strong&gt;. Like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Replace wheel bearings&lt;br&gt;&lt;/li&gt;&#xA;&lt;li&gt;Remove/repair/reinstall wheels&lt;br&gt;&lt;/li&gt;&#xA;&lt;li&gt;Replace safety wiring and cotter keys&lt;/li&gt;&#xA;&lt;li&gt;Service landing gear struts by adding oil/air&lt;/li&gt;&#xA;&lt;li&gt;Lubrication not requiring disassembly of non-structural items like cover plates, cowlings, and fairings&lt;/li&gt;&#xA;&lt;li&gt;Simple fabric patches not requiring rib stitching or removing structural parts or control surfaces&lt;/li&gt;&#xA;&lt;li&gt;Replenishing hydraulic fluid&lt;/li&gt;&#xA;&lt;li&gt;Refinishing decorative coating of fuselage and other parts&lt;/li&gt;&#xA;&lt;li&gt;Repairing upholstery without disassembly&lt;/li&gt;&#xA;&lt;li&gt;Simple repairs to fairings, etc&lt;/li&gt;&#xA;&lt;li&gt;Replacing side windows&lt;/li&gt;&#xA;&lt;li&gt;Replacing safety belts&lt;/li&gt;&#xA;&lt;li&gt;Replacing seats or seat parts with approved replacements&lt;/li&gt;&#xA;&lt;li&gt;Troubleshooting and repairing broken circuits in landing light wing circuits&lt;/li&gt;&#xA;&lt;li&gt;Replacing bulbs, reflectors, and lenses of position and landing lights&lt;/li&gt;&#xA;&lt;li&gt;Replacing wheels and skis where no weight and balance computation is required&lt;/li&gt;&#xA;&lt;li&gt;Replacing cowling not requiring removing the propeller or disconnecting flight controls&lt;/li&gt;&#xA;&lt;li&gt;Replacing or cleaning spark plugs and setting gap clearance&lt;/li&gt;&#xA;&lt;li&gt;Replacing any hose connection except hydraulic connections&lt;/li&gt;&#xA;&lt;li&gt;Replacing prefabricated fuel lines&lt;/li&gt;&#xA;&lt;li&gt;Cleaning or replacing fuel and oil strainers or filter elements&lt;/li&gt;&#xA;&lt;li&gt;Replacing and servicing batteries&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And others &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/PIC-archive/Aircraft-Ownership/Preventive-Maintenance&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, note that it has to be &lt;strong&gt;your&lt;/strong&gt; airplane, and it can't be used commercially (which I think includes offering it for rent). There is very little you can do in the way of avionics (read #31 and #32 in the reference I gave). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fun thing to note is that although a PPL is required, the PPL training does not give any special attention to any of these items, and therefore really somebody off the street is technically just as qualified as a private pilot, but the private pilot is the only one &lt;em&gt;authorized&lt;/em&gt; to do the work (provided they own the plane). When I got my PPL, nobody walked me through replacing cotter pins or anti-back-out devices...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt;&#xA;These rules though may be different when you get into experimental category aircraft but I can't source it now and will do more research and edit when I can clarify.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="5517" LastEditDate="2016-01-21T15:00:40.187" LastActivityDate="2016-01-21T15:00:40.187" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="24470" PostTypeId="2" ParentId="24455" CreationDate="2016-01-20T04:11:19.493" Score="8" Body="&lt;p&gt;Twist is closely coupled to the wing's sweep angle, airfoil camber, taper ratio and the desired level of static longitudinal stability. Other factors are the desired spanwise lift distribution and maneuverability. There is no simple, general formula: In the end twist, or, more precisely, local reflex camber, is the consequence of your selection of the parameters mentioned above. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Background&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12507/what-does-it-mean-for-a-plane-to-be-aerodynamically-stable/12511?s=4%7C0.1008#12511&quot;&gt;Static longitudinal stability&lt;/a&gt; means that the aircraft will return to the trimmed angle of attack after a disturbance. This is made possible by producing proportionally more lift in the forward part of the wing than in the rear part. Reflex airfoils do it all by themselves and &lt;a href=&quot;https://en.wikipedia.org/wiki/Fauvel_AV.36&quot; rel=&quot;nofollow noreferrer&quot;&gt;unswept flying wings&lt;/a&gt; do not need washout, but a proper reflex airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Horten flying wings had highly tapered wings and used a bell-shaped lift distribution over span which produced a small downforce at the tips. This helped a lot to reduce adverse yaw and allowed them to do away with a vertical tail. Also this made stall chararcteristics benign. This lift distribution was reached by extensive washout (&lt;a href=&quot;http://www.century-of-flight.net/Aviation%20history/flying%20wings/Hortens%20Design.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;as much as 8°&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you add stability by computer control, washout will not be needed and you can use an elliptical planform for best performance. This will, however, have &lt;a href=&quot;https://aviation.stackexchange.com/questions/22757/what-is-the-reason-for-the-poor-low-speed-characteristics-of-sweptback-wings/22758?s=2%7C0.2040#22758&quot;&gt;unfavorable stall characteristics&lt;/a&gt; and needs wing fences when the wing is swept. &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292#9292&quot;&gt;Moderate sweep&lt;/a&gt; adds stability and damping, but above a critical combination of aspect ratio and sweep angle it is hard to achieve satisfactory stall characteristics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/orBOy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/orBOy.png&quot; alt=&quot;Critical angle of sweep for swept wings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Critical angle of sweep for swept wings, from Chapter 16 of S. Hoerner's &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/9998831636&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fluid Dynamic Lift&lt;/a&gt;. Too much aspect ratio and sweep will result in a strong pitch-up when the wing stalls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By adding some chord at the outer wing you can twist the local incidence by the amount of chord added. This will lower the local lift coefficient and produce reserves at stall which will improve stall characteristics a lot. &lt;a href=&quot;http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/17682-karl-nickels-falter-1-tailless-aircraft.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Karl Nickel&lt;/a&gt; has published a method for calculating the optimum planform for a given static stability with nearly elliptic lift distribution over a wide range of speeds. The key is his insight that by trimming the wing for a particular angle of attack the pilot will adjust local washout by moving the &lt;a href=&quot;https://aviation.stackexchange.com/questions/17128/how-is-pitch-controled-in-a-flying-wing/17130#17130&quot;&gt;elevons&lt;/a&gt; trailing edge up. Ideally, the wing uses several elevons with increasing trim deflection towards the wingtip. (By &lt;a href=&quot;https://aviation.stackexchange.com/questions/164/what-does-the-term-trimming-most-commonly-mean-in-aviation&quot;&gt;&quot;trimming&quot;&lt;/a&gt; I do not only mean the reduction of stick forces, but also the adjustment of local lift to cancel any pitching moments.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that now the planform is tightly coupled to the static margin and, consequently, to the location of the center of gravity (cg). Flying with a more forward location of cg than ideal means more negative elevon deflection angles and lower local lift at the tips than ideal, and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SB-13 flying wing glider uses this technique and has a taper ratio (ratio of tip to root chord) of 0.8. It uses two elevons over the outer 50% of span, the inner of which travels 1/3 of the trim deflection of the outer elevon. Twist is zero for the inner half of the wing, changes from 0° to -1.5° over the 0.15 m section where the root airfoil (HQ 34 N) changes over to the tip airfoil (HQ 36 K) to adjust for their difference in zero-lift angle and increases again linearly towards the tip to +0.5° (I hope I got that detail right, typing all this from memory). The negative washout was chosen to allow the elevons to have 4° twist themselves, so in sum (fixed wing and elevons) the wing has increasing twist towards the tips. In flight, the elevons will always have a slightly negative deflection, so the effective washout is even stronger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cs5Gk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cs5Gk.jpg&quot; alt=&quot;SB-13 in flight with Hans-Jürgen Berns at the controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SB-13 in flight (picture &lt;a href=&quot;http://www.akaflieg-braunschweig.de/prototypen/sb13/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;To answer your questions directly:&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is (a) twist needed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not necessarily. An unswept flying wing does not benefit much from twist. It will only help to add some stall margin at the tips. A positively swept flying wing can also get away without twist if the airfoil is changed over span from positive camber at the root to negative camber at the tip. If the same airfoil is used over the whole span, twist/reflex camber is necessary and cannot be avoided as soon as the cg is ahead of the neutral point: It will result from trimming the wing for the desired angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How do I to calculate it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Select your desired static margin.&lt;/li&gt;&#xA;&lt;li&gt;Select your desired lift distribution over span. An elliptic distribution will result in the lowest induced drag, and a bell-shaped distribution will give better maneuverability.&lt;/li&gt;&#xA;&lt;li&gt;Select the planform that results in the desired lift distribution when trim changes over speed are considered. Use several elevons over span to be able to adjust the local incidence independently.&lt;/li&gt;&#xA;&lt;li&gt;Twist is then a necessary consequence of trimming the aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-20T07:11:46.510" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24471" PostTypeId="1" AcceptedAnswerId="49729" CreationDate="2016-01-20T04:31:12.977" Score="10" ViewCount="1539" Body="&lt;p&gt;I was reading about a C-124 that was carrying three nuclear weapons over the Atlantic, and developed engine trouble. The article said that two of the weapons were jettisoned into the ocean for safety reasons. I was wondering how you can drop something from a C-124 in flight? Unless they were small enough to push out the back side doors. This happened on July 28, 1957.&lt;/p&gt;&#xA;" OwnerUserId="11931" LastEditorUserId="19" LastEditDate="2016-06-24T10:57:02.910" LastActivityDate="2020-05-24T06:02:48.897" Title="How can cargo be jettisoned from a C-124 in flight?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;military&gt;&lt;emergency&gt;" AnswerCount="5" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24472" PostTypeId="2" ParentId="24471" CreationDate="2016-01-20T04:42:13.827" Score="1" Body="&lt;p&gt;If you are desperate enough, even front cargo doors can be opened in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zbn04.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zbn04.jpg&quot; alt=&quot;C-124 Globemaster II being unloaded&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;C-124 Globemaster II being unloaded (picture &lt;a href=&quot;http://farm5.staticflickr.com/4035/4445269111_f98a098a19_z.jpg?zz=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the hinge line is almost in flight direction. When flying slowly, the aerodynamic loads are small enough to crack the doors open. Actually, their shape will result in a suction force over most of their length, so the hard part is closing them again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the doors are slightly open, the load can be pushed out without much change in the center of gravity since the forward edge of the cargo floor is only slightly forward of the wing's leading edge.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-20T04:42:13.827" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24473" PostTypeId="2" ParentId="19391" CreationDate="2016-01-20T05:03:23.480" Score="9" Body="&lt;p&gt;The cause of the accident of a &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Express&quot; rel=&quot;noreferrer&quot;&gt;DH 86 Express&lt;/a&gt; on 2 October 1935 is not confirmed, but likely caused by a cigarette, albeit indirectly. From the Wikipedia article on the DH 86:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On 2 October 1935 Holyman's VH-URT Loina was also lost in Bass Strait,&#xA;  again with no survivors. This time a significant amount of wreckage&#xA;  was recovered from the sea and from beaches on Flinders Island.&#xA;  Investigation of the wreckage revealed a section of charred carpet on&#xA;  a piece of cabin flooring from just ahead of the lavatory door. It was&#xA;  thought possible that a small fire from a dropped cigarette had led to&#xA;  someone running aft suddenly to stamp it out – the sort of sudden&#xA;  change in weight distribution that could set up a fatal loss of&#xA;  directional control while the aircraft was on a low-speed landing&#xA;  approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-20T05:03:23.480" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24474" PostTypeId="1" CreationDate="2016-01-20T05:30:59.837" Score="8" ViewCount="324" Body="&lt;p&gt;Is it true that in the latest generation of Boeing aircraft some software components / Electronic Flight Bag data can be pushed to the flight remotely via a Wireless link? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, what sort of safeguards are in place to preserve the integrity of such an update? How does the aircraft authenticate that the data sent is indeed legitimate? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious to know the details. e.g. Are these conventional Ethernet networks over which the update gets pushed at the airport end? Is the final wireless transmission done by a COTS WiFi router? Does the update travel via the internet from (say) Boeing till the airport?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="1696" LastEditDate="2016-07-05T20:06:23.013" LastActivityDate="2016-07-05T20:06:23.013" Title="What has been done to provide security for remote wireless updating of in-aircraft software components?" Tags="&lt;boeing&gt;&lt;security&gt;&lt;software&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24475" PostTypeId="1" CreationDate="2016-01-20T06:46:50.653" Score="-1" ViewCount="93" Body="&lt;p&gt;I am a high school graduate who loves aircraft designing and are aiming to get into universities that has aerospace engineering majors. However, I have heard people saying that since aircraft companies will keep their designers in the company until they retire, there is little oppurtunity to get into this industry. Is is true? If it is not, then where can I find more oppurtunities?&lt;/p&gt;&#xA;" OwnerUserId="13078" LastActivityDate="2016-01-20T08:37:27.957" Title="Are aircraft designers in demand in Canada/US in near future?" Tags="&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-01-20T12:51:48.670" ContentLicense="CC BY-SA 3.0" />
  <row Id="24476" PostTypeId="2" ParentId="24474" CreationDate="2016-01-20T07:29:43.930" Score="6" Body="&lt;p&gt;Boeing claims in &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/787_ground_wireless_system.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 787 uses wireless (802.11 b/g) technology while at the gate to&#xA;  transfer maintenance data and update the Electronic Flight Bag (EFB).&#xA;  This is referred to as “e- Enabling” and it will allow airlines flying&#xA;  the 787 to operate more efficiently.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, yes, they use a regular WLAN connection for transmitting data while on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The document continues:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Upon weight on wheels the 787 attempts to authenticate specific ground&#xA;  access points. Information regarding the key configuration&#xA;  requirements and how the 787 authentication occurs requires the&#xA;  signing of a PIA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I interpret PIA as Proprietary Information Agreement, a form of secrecy agreement. Boeing uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Security_through_obscurity&quot; rel=&quot;noreferrer&quot;&gt;security through obscurity&lt;/a&gt; to safeguard the integrity of the connection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know more, Boeing advises to contact 787terminalwireless@boeing.com. However, I doubt they will talk to you or me unless we are airport representatives with a credible need to know.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-20T07:51:46.027" LastActivityDate="2016-01-20T07:51:46.027" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24477" PostTypeId="2" ParentId="2354" CreationDate="2016-01-20T07:45:30.670" Score="13" Body="&lt;p&gt;Contrary to voretaq7's highly upvoted answer, the green coating in your first image is NOT a primer. It's a spray-on plastic protective coating usually referred to as &amp;quot;Temporary Protective Coating (TPC)&amp;quot;. This is used primarily as a barrier to oxidation, as there is a very thin layer of very pure aluminum on the exterior surface of the skin.&lt;/p&gt;&#xA;&lt;p&gt;During some of the videos available of the painting process for a new aircraft, you will see them spray a chemical over the entire airplane as the first step. This chemical dissolves the TPC, and leaves a super-shiny aluminum surface for them to then proceed to paint.&lt;/p&gt;&#xA;&lt;p&gt;The primer paint used on the exterior of the skin during the full paint process is usually a yellow color, not the traditional &amp;quot;Boeing green&amp;quot; seen on interior parts that don't get a final paint coat.&lt;/p&gt;&#xA;&lt;p&gt;As for why white is the primary color of choice, I unfortunately do not know. However I would point out that Southwest Airlines does not use a white base-coat on their current livery (term for the paint scheme), American Airlines' new 787's are actually a very light blue, and there was the Air New Zealand black 787 shown in another answer...&lt;/p&gt;&#xA;&lt;p&gt;Source/Disclaimer: I am employed by Boeing on the Commercial production lines.  Information I have provided  is, to the best of my knowledge, accurate and not considered proprietary.&lt;/p&gt;&#xA;" OwnerUserId="13080" LastEditorUserId="13080" LastEditDate="2020-07-01T18:07:16.853" LastActivityDate="2020-07-01T18:07:16.853" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24478" PostTypeId="2" ParentId="24475" CreationDate="2016-01-20T08:37:27.957" Score="1" Body="&lt;p&gt;It is not necessary to have an Aerospace Engineering degree to get a foothold into the engineering side of aviation. Most of the major aircraft companies operate on a very long design cycle, and maintaining employees with specialty engineering disciplines is not cost effective. While there will likely always be SOME aerospace engineers employed by companies like Boeing, the majority of their engineers are Mechanical, Electrical, Industrial, Manufacturing, and Tooling engineers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mechanical engineering, in particular, would open you up to a much broader base of job opportunities all over, both in and out of the aerospace industries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An invaluable resource for you as you look at your choices, is the Occupational Outlook Handbook, created by the US Bureau of Labor Statistics. In it is listed expected salaries, expected job growth opportunities, how competitive the field is, etc. For Aerospace engineering, for example, &lt;a href=&quot;http://www.bls.gov/ooh/architecture-and-engineering/aerospace-engineers.htm&quot; rel=&quot;nofollow&quot;&gt;http://www.bls.gov/ooh/architecture-and-engineering/aerospace-engineers.htm&lt;/a&gt; indicates that the market is expected to decline by an average rate of 2% over the course of 2014-2024. This would indicate that Aerospace Engineers are not in high demand. However, Mechanical Engineers are expected to grow by an average of 5% in the same time period.&lt;/p&gt;&#xA;" OwnerUserId="13080" LastActivityDate="2016-01-20T08:37:27.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24479" PostTypeId="1" CreationDate="2016-01-20T10:24:47.837" Score="0" ViewCount="1533" Body="&lt;p&gt;I am referring to the mechanism used in aircraft carriers, which help in catapulting fighter aircraft. What I had in mind is a milder version of the same concept. It would massively save cost, due to it being operated by electric power, save energy and time of the pilots, less exertion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would such a system be feasible?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2016-01-20T19:49:34.477" Title="Would a chain strip built in the airport taxiways, help airlines in saving money and time during taxi?" Tags="&lt;taxiing&gt;" AnswerCount="6" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24480" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T10:39:31.703" Score="12" Body="&lt;p&gt;Airports already have several ways to move aircraft along taxiways&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft engines (least economical but always available)&lt;/li&gt;&#xA;&lt;li&gt;Tugs (often used for pushback from terminals)&lt;/li&gt;&#xA;&lt;li&gt;Aircraft wheel-motors (some makers are at least planning for electric taxi)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A system of fixed chains along a complex network of intersecting taxiways would be expensive to install and maintain and might be unreliable (e.g. icing up in cold weather). &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;See also&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/9101/1289&quot;&gt;Does it make sense towing airplanes to the head of airstrip by external means?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-20T10:39:31.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24481" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T11:44:46.597" Score="8" Body="&lt;p&gt;An airport has taxiways that cross other taxiways and runways, so any chain system would require breaks in the chains at these points. Airplanes would need some sort of motive power to cross these breaks, it's impractical and slow for an airplane to spin up its engines for 20 seconds to cross a break in the chain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A chain system would also be very expensive to install and run, probably more expensive than the fuel it takes to taxi the airplanes. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-01-20T11:44:46.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24482" PostTypeId="1" AcceptedAnswerId="24486" CreationDate="2016-01-20T12:13:17.043" Score="8" ViewCount="1562" Body="&lt;p&gt;How many fuel pumps does a &lt;a href=&quot;https://en.wikipedia.org/wiki/Diamond_DA20&quot; rel=&quot;nofollow&quot;&gt;Diamond DA20&lt;/a&gt; have? And since the fuel pump sends fuel to the engine, if you turn it off after the takeoff as the check list says, how will the fuel reach the engine?&lt;/p&gt;&#xA;" OwnerUserId="12552" LastEditorUserId="62" LastEditDate="2016-01-20T17:35:21.903" LastActivityDate="2016-01-20T17:35:21.903" Title="How many fuel pumps does a Katana DA20 have?" Tags="&lt;aircraft-systems&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24484" PostTypeId="2" ParentId="24471" CreationDate="2016-01-20T12:55:02.513" Score="12" Body="&lt;p&gt;The C-124 had a opening in the rear, through which cargo (or paratroopers) could be dropped. From &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/c-124.htm&quot; rel=&quot;noreferrer&quot;&gt;globalsecurity.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The C-124 was also used for airdrops. ... In the back of the plane, the underneath of the airplane had elevator doors that opened up and the crew could drop cargo out, or paratroopers could jump out. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is an image of the elevator doors in open position&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/omiex.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/omiex.jpg&quot; alt=&quot;C-124&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The rear elevator opening of the Douglas C-124 Globemaster II where an elevator platform could be lowered or raised for bulk cargo operations (often the platform was removed so an interior hoist could directly move cargo)&lt;/em&gt; — photo by Joseph May; image from travelforaircraft.wordpress.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a C-124 using that door for an airdrop, presumably in Antarctica (I've put the image as I came across; I'm pretty sure that it's rotated)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FpCOw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FpCOw.jpg&quot; alt=&quot;C-124 airdrop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from antarctica.recollect.co.nz&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew must've used the rear door rather than the front one for jettisoning the nuclear weapon. The &lt;a href=&quot;https://archive.org/stream/AFRRISpecialReportDODNuclearMishaps/AFRRI%20Special%20Report%20DOD%20Nuclear%20Mishaps_djvu.txt&quot; rel=&quot;noreferrer&quot;&gt;text of the official report&lt;/a&gt; reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The C-124 aircraft was en route from Dover AFB, Delaware, when &#xA;  a loss of power from the number one and number two engines was experienced. &#xA;  Maximum power was applied to the remaining engines, but level flight could not be maintained. At this point, the decision was made to jettison cargo in the interest of safety of the crew and aircraft. Three weapons and one nuclear capsule were aboard the aircraft, and nuclear components had not been installed in the weapons. The first weapon was jettisoned at 4,500 feet altitude. The second weapon was jettisoned at approximately 2,500 feet altitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;With the difficulties the crew was experiencing in keeping the aircraft level, it would only be logical that the rear doors were used, not the front.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-20T12:55:02.513" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24485" PostTypeId="2" ParentId="24467" CreationDate="2016-01-20T13:01:28.080" Score="2" Body="&lt;p&gt;The first question is decently answerable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Composites have the nice property that they are not homogeneous at a mesoscopic scale. It's almost unavoidable that small cracks form in materials under stress. This happens in aluminium, titanium and composites alike. This is not dangerous if there's something to stop them from growing. Within aerospace composites, the local material boundaries stop crack growth. Practically speaking, for a laminar composite this means that one layer may develop a crack. The two adjacent layers will stay glued to both sides of the crack, and keep the panel together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Composites are also easier to engineer for some specific purposes, such as having higher tensile strengths in critical directions. This isn't impossible for titanium, but it is &lt;strong&gt;hugely&lt;/strong&gt; expensive. You have to grow and cut a single crystal of titanium. In comparison, with a carbon composite it's just a matter of orienting the fiber layers.&lt;/p&gt;&#xA;" OwnerUserId="1956" LastActivityDate="2016-01-20T13:01:28.080" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24486" PostTypeId="2" ParentId="24482" CreationDate="2016-01-20T13:07:07.433" Score="14" Body="&lt;p&gt;There are 2 fuel pumps on the Diamond DA20. One is electric and is controlled by the pilot and one is mechanically driven by the engine and is constantly running while the engine is running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After take off, you switch the electric one off and the mechanical one keeps supplying the engine with fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/560qy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/560qy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2016-01-20T13:07:07.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24488" PostTypeId="1" CreationDate="2016-01-20T13:22:51.530" Score="0" ViewCount="93" Body="&lt;p&gt;As we know, at higher altitudes the dose of UV rays increases, and planes usually spend a larger time there, then why aren't windows of airplanes made UV proof. A simple coating on the inside might solve the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21703/are-suns-uv-rays-more-harmful-on-an-airplane-at-high-altitude&quot;&gt;Relevant question&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-01-20T13:22:51.530" Title="Are aircraft windows UV-ray proof?" Tags="&lt;windows&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2016-01-20T21:45:28.377" ContentLicense="CC BY-SA 3.0" />
  <row Id="24489" PostTypeId="1" CreationDate="2016-01-20T13:44:46.210" Score="24" ViewCount="15746" Body="&lt;p&gt;Why hasn't diesel caught on much for aircraft engines?  The list of diesel aircraft engines on Wikipedia is very short. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I see mentioned is their poorer power-to-weight ratios. (e.g. &lt;a href=&quot;https://aviation.stackexchange.com/questions/3519/what-are-the-advantages-disadvantages-of-diesel-jet-a-1-piston-engine&quot;&gt;What are the advantages/disadvantages of diesel/Jet A-1 piston engine?&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I knew this was true in the past but is it true even today? Does anyone have values comparing the power-to-weight rations of typical diesel vs gasoline engines, say for automotive use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, doesn't the better efficiency, especially at higher altitudes compensate for the poorer power-to-weight ratio by allowing lesser fuel and more payload?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;50 years ago diesel engines for automobiles were uncommon too but in the last decade they have been steadily making headway in the car market. Do the same developments translate to the aircraft engine  selection too?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than weight, are there any other disadvantages of diesel? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2018-03-08T14:14:45.770" Title="Why are piston engines for aircraft rarely diesel powered?" Tags="&lt;engine&gt;&lt;fuel&gt;&lt;piston-engine&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24490" PostTypeId="2" ParentId="24489" CreationDate="2016-01-20T14:43:34.777" Score="7" Body="&lt;p&gt;Although this has partially been covered in &lt;a href=&quot;https://aviation.stackexchange.com/questions/3519/what-are-the-advantages-disadvantages-of-diesel-jet-a-1-piston-engine&quot;&gt;this question&lt;/a&gt;, it's different enough to warrant an answer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One word: cost&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the vast majority of light piston aircraft the benefits of diesel are way lower than the costs in involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Diesel engines are heavy, this is because the diesel cycle relies on cylinder pressure rather than a spark to ignite the fuel-air mix. This means that diesel engine blocks have to be at least part steel, as aluminum is not strong enough to contain the pressures. All the aero-diesel engines I have read about have a hybrid steel-aluminum block, which is harder and more expensive to manufacture. The weight of the engine has the following impact on costs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You have to have a variable pitch prop in order to get the same amount of performance&lt;/li&gt;&#xA;&lt;li&gt;The extra weight up front means that you have to re-arrange the balance of the airplane, moving parts from the front to the aft&lt;/li&gt;&#xA;&lt;li&gt;Diesel fuel requires a complete re-working of the fuel system, so the wings have to be completely opened up for new tanks and the new piping. Some of this piping is to cycle warmed fuel through the tanks to prevent the fuel from gelling at low temperatures&lt;/li&gt;&#xA;&lt;li&gt;Although diesels do not require a spark they are heavily computerized, so they require steady electrical power to operate. 2 batteries are required for redundancy. More weight, more cost&lt;/li&gt;&#xA;&lt;li&gt;The aircraft has to have a STC (supplemental type conversion) in order to be legal. If your airplane doesn't have one you'd have to pay for it yourself, which costs tens of thousands to millions of dollars to do&lt;/li&gt;&#xA;&lt;li&gt;Your dashboard has to be modified for the new instruments and controls&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So not only are the engines more expensive in the first place, fitting them is very expensive as well. Unless your airplane is going to fly a lot it would take decades to recoup the costs. Many of the other downsides (lack of Jet A1 fuel at many GA airfields, lack of engineering support for the engines, etc) would go away if it was cheaper to get a diesel installed. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-01-21T09:07:59.567" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24491" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T14:58:47.900" Score="2" Body="&lt;p&gt;Also, note that the modifications to fighter planes (Air Force vs Navy) are fairly significant, as the forces on the plane (and humans inside) are significant when using the arrestor (sp?) cables on aircraft carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, reducing the force is possible, but reducing it so that all existing planes flying could use it may (mostly) eliminate its benefit.&lt;/p&gt;&#xA;" OwnerUserId="13087" LastActivityDate="2016-01-20T14:58:47.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24492" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T15:57:07.923" Score="3" Body="&lt;p&gt;They don't do it for roughly the same reasons that they don't install such systems in roads.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Expensive modifications would be required to every aircraft of a vast array of aircraft types. This alone would probably mean that you'd never recover the costs over the entire expected life of the system. And getting modifications approved by the relevant regulatory agencies for airworthy aircraft designs is even more of a pain than getting them approved for road-worthy car designs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The systems themselves would be quite expensive for initial install, especially if they were designed to operate in all weather conditions in which airports can currently operate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Being able to drive where you want is much more flexible (which is somewhat less of a concern at an airport than on roads, but still a concern.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Stopping or turning suddenly to avoid a collision (like when &lt;a href=&quot;http://www.cbsnews.com/news/southwest-to-help-investigate-runway-close-call/&quot; rel=&quot;nofollow noreferrer&quot;&gt;you're cleared to taxi across a runway and suddenly realize that there's a Learjet taking off on it&lt;/a&gt;) might not be possible or would at least be slower.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In short, there are already cheaper alternatives that don't suffer these drawbacks, such as tugs (manual or automated,) electric motors on the gear, and, of course, aircraft engines, as mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/a/24480/755&quot;&gt;RedGrittyBrick's answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-20T15:57:07.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24493" PostTypeId="2" ParentId="24467" CreationDate="2016-01-20T16:29:50.447" Score="3" Body="&lt;p&gt;&quot;The application of aircraft&quot; is extremely vague. &lt;a href=&quot;https://aviation.stackexchange.com/q/12958/1696&quot;&gt;Modern aircraft use all of these materials in many different places&lt;/a&gt;, for many different reasons. Each component will have different tradeoffs that depend on many factors. The following is an extremely general overview.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aluminum is a popular material in aircraft because it is relatively cheap and light, and has alloys with good material properties. It is fairly easy to work with but must be protected from corrosion. Light weight and low cost mean that it is used in large areas like fuselage and wing skin, and for a lot of the underlying structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Titanium is useful for its ability to withstand higher temperatures, while being stronger than aluminum but also heavier. However, it is much more expensive than aluminum. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Composites are a large family of materials, with many different types and combinations possible. Composites can be strong and light, but don't withstand high temperatures as well. Although composites don't corrode like some metals, some situations such as carbon fiber contacting aluminum need to be avoided. Exposure to UV light or moisture can also be an issue. Manufacturing composites can become very expensive depending on the materials used. Since composites are typically manufactured from multiple layers sandwiched together, they lend themselves more easily to applications with large and thin sections. Larger and more complex parts are more difficult to make from composites. Another important factor with aircraft is electrical conductivity. While metal parts will naturally conduct electric charge between each other, composites will need special treatment to ensure conductivity for protection from lightning and static charges.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also many other considerations. Besides yield strength, many materials on aircraft need to have good fatigue properties to withstand cyclic loading over time. Material properties at high and/or low temperatures may also be important. While metals tend to bend and dissipate energy before breaking, composites tend to &lt;a href=&quot;https://aviation.stackexchange.com/q/22148/1696&quot;&gt;suddenly snap&lt;/a&gt;. Metals are also easier to inspect and repair, while composites can be &lt;a href=&quot;https://aviation.stackexchange.com/q/22153/1696&quot;&gt;much more complicated&lt;/a&gt;. While a metal can be categorized fairly well by its type and dimensions, composites are more complex with their multiple plies. This makes definition and analysis more complicated.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-20T16:29:50.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24494" PostTypeId="1" CreationDate="2016-01-20T16:56:09.170" Score="12" ViewCount="4355" Body="&lt;p&gt;How is the induced drag calculated for a wing with elliptical planform ? Is this wing shape the most efficient ?&lt;/p&gt;&#xA;" OwnerUserId="7966" LastEditorUserId="19" LastEditDate="2016-07-14T07:18:01.763" LastActivityDate="2016-07-14T07:18:01.763" Title="How is the induced drag calculated for a wing with elliptical planform?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24495" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T17:07:30.883" Score="3" Body="&lt;p&gt;One point has been missed in the other fine answers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an aircraft carrier, the nose gear of each aircraft has a pull bar installed that links with the catapult sled. This pull bar is manually engaged by a deck crew member for each aircraft that is to launch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to do this at an airport, there would need to be a ground handler stationed at each runway turn-off point to engage the pull bar to get the aircraft moving. I pity the poor souls who would have to stand next to a runway at KBOS or KJFK in the wonderful weather they are expecting this weekend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible that this system could be automated, but that's another very expensive design element that has to be brought into play, tested, and receive CAA certification. &lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="12220" LastEditDate="2016-01-20T19:49:34.477" LastActivityDate="2016-01-20T19:49:34.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24496" PostTypeId="1" CreationDate="2016-01-20T18:02:40.057" Score="0" ViewCount="344" Body="&lt;p&gt;If I were to fly direct from from East to West, and then in the same aircraft do the return trip from West to East, assuming there is no wind on the earth, would both journeys take the same amount of time? This is of interest because logic tells me that the Earth's rotation should make the return trip longer.  &lt;/p&gt;&#xA;" OwnerUserId="13089" LastEditorUserId="12220" LastEditDate="2016-01-21T17:01:09.623" LastActivityDate="2016-01-21T17:01:09.623" Title="East-West and West-East flight times in relation to earth's rotation" Tags="&lt;transatlantic&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-01-20T20:14:40.930" ContentLicense="CC BY-SA 3.0" />
  <row Id="24497" PostTypeId="2" ParentId="24479" CreationDate="2016-01-20T19:09:33.377" Score="3" Body="&lt;p&gt;In addition to all the 'minor' drawbacks already discussed, there is one huge, basic problem with this idea. What has to be moved is an airplane, weighing less than about 600 tonnes, designed to move, with a manageable rolling resistance. A chain or cable system extensive enough to take its payload everywhere it should go adds many tonnes of metal to move with a lot of friction, that will only grow as water and dirt enter the trench. The whole thing will need enormous horsepower just to get moving even without an aircraft attached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to a tug, or even compared to an aircraft taxiing under its own power, this will simply need too much energy to be feasible. The only place where this system can make money is in some streets in San Francisco.&lt;/p&gt;&#xA;" OwnerUserId="3353" LastActivityDate="2016-01-20T19:09:33.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24498" PostTypeId="1" AcceptedAnswerId="24504" CreationDate="2016-01-20T21:03:00.160" Score="11" ViewCount="4639" Body="&lt;p&gt;We have had &lt;a href=&quot;https://aviation.stackexchange.com/questions/9101/does-it-make-sense-towing-airplanes-to-the-head-of-airstrip-by-external-means&quot;&gt;more&lt;/a&gt;... &lt;a href=&quot;https://aviation.stackexchange.com/questions/16874/what-is-the-cost-savings-of-using-electronic-motors-to-taxi&quot;&gt;than&lt;/a&gt;... &lt;a href=&quot;https://aviation.stackexchange.com/questions/24430/why-dont-large-commercial-airplanes-have-electric-motors-in-the-wheels&quot;&gt;one&lt;/a&gt; question about jet aircraft taxiing about the airport without their jet engines running. Those address several issues such as cost vs savings and regulatory approval.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question assumes that an in-wheel electric motor, tug or even &lt;a href=&quot;https://aviation.stackexchange.com/questions/24479/would-a-chain-strip-built-in-the-airport-taxiways-help-airlines-in-saving-money&quot;&gt;pull-chain&lt;/a&gt; based solution has been developed, certified, deemed cost-effective and installed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say that I am now sitting on the taxi-way and am 5th in line for take off. It's time to fire up those jets so they can warm up and we can get the beast into the air. According to this question about &lt;a href=&quot;https://aviation.stackexchange.com/questions/1959/how-are-turbine-engines-started&quot;&gt;how turbine engines are started&lt;/a&gt;, it appears that I'm going to need some sort of ground-based support to get the N2 stage spinning. That question indicates that a couple of early, WWII era, jet engines had a built in motor that could get the turbines spinning fast enough for a start, but it seems to me that any modern commercial air-carrier grade engine will need some sort of external help to fire up. I suppose if there was a tug that had pulled me to this point, it could have the support infrastructure built in to get the turbines spinning, but any sort of self- (or ground-) propelled system would seem to lack that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Now that we're nowhere near the terminal, how the heck are we going to start the engines?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;I realize that this question is somewhat speculative in nature, but I believe it could be answered based on some existing or in-development ability (that I'm not aware of) to start an engine without ground support. It could also be my misunderstanding that ground support is &lt;em&gt;not&lt;/em&gt; required to start a modern commercial aircraft engine (GE90, RR Trent series, LEAP etc.)&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2020-02-11T07:04:14.750" Title="Is starting a jet engine without ground support possible?" Tags="&lt;jet-engine&gt;&lt;taxiing&gt;&lt;turbine&gt;&lt;engine-starting&gt;" AnswerCount="6" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24499" PostTypeId="2" ParentId="24498" CreationDate="2016-01-20T21:13:27.957" Score="1" Body="&lt;p&gt;Most of the time, the APU of the aircraft is kept running when the airplane is on the ground to provide the bleed air and electrical power to start up the main engines. As it happens, the APU does not need bleed air to start up so if you are starting the airplane up after leaving it, say overnight, you can start the APU up first and then start up the rest of the engines and voilà, you can take-off now. That is how it works on jet aircraft so no one gets stuck in an airport in the middle of nowhere.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-01-20T21:23:46.097" LastActivityDate="2016-01-20T21:23:46.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24500" PostTypeId="2" ParentId="24498" CreationDate="2016-01-20T21:38:44.330" Score="7" Body="&lt;p&gt;This depends on the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most large jet aircraft are equipped with an &lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;nofollow noreferrer&quot;&gt;APU (Auxiliary Power Unit)&lt;/a&gt;. This is a small turbine power source usually in the back of the plane that can be started using only the onboard batteries. Once started the APU can provide electrical power as well as &lt;a href=&quot;https://aviation.stackexchange.com/questions/15520/why-there-is-apu-bleed-air-supply&quot;&gt;bleed air to start the engines&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all planes (but most modern ones) have an APU to provide bleed air and some require a ground based source of air pressure to start up, generally the airport has mobile units for this.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Piston planes (although not many are flown commercially any more), can generally be started by their internal batteries. If you are lucky enough to be in a piston plane form the 30's or 40's you may encounter a &lt;a href=&quot;https://en.wikipedia.org/wiki/Coffman_engine_starter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coffman Starter&lt;/a&gt; which basically uses a blank shotgun shell to generate pressure in the cylinder and turn the engine over. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small turbo props often have turbines small enough to be started by an electric starter. This extends to some small jets as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a plane is out on the ramp and for what ever reason the batteries are dead or they die trying to start the APU, most airports have portable &lt;a href=&quot;http://www.trade-a-plane.com/for-sale/parts/Ground+Support+Equip+_+FBO+Supplies/Ground+Power+Units&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ground Power Units&lt;/a&gt; that they can bring out to the plane for starting and providing power.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-20T21:38:44.330" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24501" PostTypeId="1" CreationDate="2016-01-20T23:19:30.833" Score="9" ViewCount="1212" Body="&lt;p&gt;I assume that while en route, one aircraft could simply pick up flight following and the others do not need to talk to ATC, but what about upon reaching an airport? Do they simply announce &quot;flight of xxx 10 mi east with W for full stop&quot; and get successive landing clearances, or do they all break apart before getting close to the airport? Thanks!&lt;/p&gt;&#xA;" OwnerUserId="13093" LastEditorUserId="62" LastEditDate="2016-01-20T23:42:26.607" LastActivityDate="2016-01-21T01:11:56.207" Title="How do civil aircraft flying in formation handle ATC?" Tags="&lt;air-traffic-control&gt;&lt;flying-in-formation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24502" PostTypeId="2" ParentId="24494" CreationDate="2016-01-21T00:41:56.987" Score="5" Body="&lt;p&gt;For a wing with elliptical span loading, the induced drag can be directly calculated from the  lift coefficient. The induced drag coefficient $C_{D_{i}}$ can be calculated as,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$C_{D_{i}} = \frac{C_{L}^{2}}{\pi A}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $C_{L}$ is the lift coefficient and $A$ is the aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Elliptical loading produces the minimum induced drag according to the lifting line theory, &lt;em&gt;when only the span and lift are considered&lt;/em&gt;. If other considerations come into play (like wing bending moment), the most efficient shape varies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for why the best distribution is elliptic, the equations can be readily derived from lifting line theory; basically this is because the downwash is constant along the span. A good way of reasoning why this is so is given in &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1923/naca-report-121.pdf&quot; rel=&quot;noreferrer&quot;&gt;The Minimum Induced Drag of Airfoils&lt;/a&gt; by Max Munk, NACA Report No. 121.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the distribution is the best one, the drag cannot be decreased or increased by transferring one lifting element from its old position to some new position. Now, the share of one element in the drag is composed of two parts. It takes a share in producing a downwash in neighborhood of other lifting elements and, in consequence, a change in their drag. It has itself a drag, being situated in the downwash produced by the other elements.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... In case of the lifting straight line, the two downwashes, each produced by one element in the neighborhood of the other, are equal. For this reason, the two drags of the two elements each produced by the other are equal too, and hence the two parts of the entire drag of the wings due to one element. ... hence, the entire drag due to one element is unchanged when the element is transferred from one situation to a new one of the same downwash, and the distribution is best only if the downwash is constant over the whole wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For this reason, when only the span and lift are considered, the elliptical loading gives the minimum induced drag as the downwash is constant over the wing. When the constraints are modified, other distributions and wing shapes become more efficient. For example, from &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110003576.pdf&quot; rel=&quot;noreferrer&quot;&gt;On the Minimum Induced Drag&#xA;of Wings&lt;/a&gt; by A. H. Bowers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;$\diamond$ Prandtl/Munk (1914)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Elliptical&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Constrained only by span and lift&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Downwash: $y = c$&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;$\diamond$ Prandtl/Horten/Jones (1932)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Bell shaped&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Constrained by lift and bending moment&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Downwash: $y = bx + c$&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;$\diamond$ Klein/Viswanathan (1975)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Modified bell shape&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Constrained by lift, moment and shear (minimum structure)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Downwash: $y = ax + bx + c^{2}$ &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-21T00:41:56.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24503" PostTypeId="2" ParentId="24501" CreationDate="2016-01-21T01:11:56.207" Score="10" Body="&lt;p&gt;As long as the aircraft are in formation, they are controlled as a single aircraft.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/ATC/atc0201.html&quot; rel=&quot;noreferrer&quot;&gt;US DoT OrderJO 7110.65T&lt;/a&gt; ATC General Control:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;2-1-13. FORMATION FLIGHTS&lt;/p&gt;&#xA;&lt;p&gt;a. Control formation flights as a single aircraft. When individual control is requested, issue advisory information which will assist the pilots in attaining separation. When pilot reports indicate separation has been established, issue control instructions as required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The decision to break the flight lies with the pilot in command, and the ATC then controls the aircraft individually.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Separation responsibility between aircraft within the formation during transition to individual control rests with the pilots concerned until standard separation has been attained.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Upon break-up of the formation flight, the controller initiating the break-up shall ensure that all aircraft or flights are assigned their proper equipment suffix.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-21T01:11:56.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24504" PostTypeId="2" ParentId="24498" CreationDate="2016-01-21T03:12:23.613" Score="23" Body="&lt;p&gt;Modern jet transport category aircraft have APUs and they will be running if no engines are.  Batteries on jets do not work very long with all electrical buses energized and the first thing you do after turning the batteries on is seeing that they are working correctly and then starting the APU (assuming no GPU is hooked up, if there is a GPU then starting the APU will be deferred until just before the GPU is disconnected).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, any aircraft on a theoretical no-engine taxi to the runway will have a running APU providing electricity to run the airplane and bleed air for an attempt at air conditioning (some aircraft are better at this then others).  When it is time to start the engines they can be started using the APU as the bleed air source and this is a normal method of starting and no different than the method used currently when the plane leaves the gate (and for some airplanes they only start one engine and taxi on that as long as possible before starting the other engine).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as the plane has a running APU, it can complete a normal engine start with no ground assistance.  The only limitation will be turbine warm up time, which just means you'll need to make sure the engines are started a few minutes before takeoff thrust is applied.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just an aside, but currently the only ground support strictly required is a tug to push the airplane away from the gate and someone to operate the jetbridge.  Aircraft and engine startup is self-contained unless the APU is inoperative. &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-21T03:12:23.613" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24505" PostTypeId="1" CreationDate="2016-01-21T04:52:43.393" Score="2" ViewCount="186" Body="&lt;p&gt;In &lt;a href=&quot;https://www.youtube.com/watch?v=7P9OAng32F0&quot; rel=&quot;nofollow&quot;&gt;this youtube video&lt;/a&gt;, there are several examples at 0:34, 1:15, and 1:27. You can see the runway looks wobbly. That last one appears to have at least three wobbles in it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are runways on which large commercial jumbo jets are landing, so presumably they're built to world-class standards. Do these standards allow for such wobbling along they're length? If so how is that possible?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2016-01-21T04:52:43.393" Title="Why are some runways apparently wobbly?" Tags="&lt;commercial-aviation&gt;&lt;runways&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-01-21T07:34:16.413" ContentLicense="CC BY-SA 3.0" />
  <row Id="24506" PostTypeId="2" ParentId="24494" CreationDate="2016-01-21T05:15:45.497" Score="8" Body="&lt;p&gt;Induced drag is caused by the downward deflection of the air streaming around the wing. The resulting aerodynamic force is tilted backwards by half the deflection angle, and the air flows off the wing with an added vertical speed component, producing &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;downwash&lt;/a&gt;. Increasing the downwash angle means increasing both lift and the backward tilt, so the induced drag goes up with the square of the lift produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to minimize induced drag for a given lift, this quadratic dependence means the optimum is reached when the downwash angle is constant over span.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How is the induced drag calculated for a wing with elliptical planform?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The elliptical, untwisted wing has the same angle of attack and the same lift coefficient over span, and produces the desired constant downwash angle.  To simplify things, let's assume the wing is just acting on the air with the density $\rho$ flowing with the speed $v$ through a circle with a diameter equal to the span $b$ of the wing. If we just look at this stream tube, the mass flow is $$\frac{dm}{dt} = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift $L$ is then the impulse change which is caused by the wing. With the downward air speed $v_z$ imparted by the wing, lift is: $$L = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v\cdot v_z = S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$S$ is the wing area and $c_L$ the overall lift coefficient. If we now solve for the vertical air speed, we get $$v_z = \frac{S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho}{\frac{b^2}{4}\cdot\pi\cdot\rho\cdot v} = \frac{2\cdot c_L\cdot v}{\pi\cdot AR}$$&#xA;with $AR = \frac{b^2}{S}$ the aspect ratio of the wing. Now we can divide the vertical speed by the air speed to calculate the angle by which the air has been deflected by the wing. Let's call it $\alpha_w$: $$\alpha_w = arctan\left(\frac{v_z}{v}\right) = arctan \left(\frac{2\cdot c_L}{\pi\cdot AR}\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The deflection happens gradually along the wing chord, so the mean local flow angle along the chord is just $\alpha_w / 2$. Lift acts perpendicularly to this local flow, thus is tilted backwards by $\alpha_w / 2$. In coefficients, lift is $c_L$, and the backwards component is $\alpha_w / 2 \cdot c_L$. Let's call this component $c_{Di}$: $$c_{Di} = arctan \left(\frac{c_L}{\pi\cdot AR}\right)\cdot c_L$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small $\alpha_w$s the arcus tangens can be neglected, and we get this familiar looking equation for the backwards-pointing component of the reaction force: $$c_{Di} = \frac{c_L^2}{\pi\cdot AR}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the circulation over span has an elliptic distribution, the local change in circulation times the local amount of circulation is constant, and the induced drag $c_{Di}$ is at it's minimum. If this would be different, a higher local $v_z$ causes a quadratic increase in local induced drag, so the whole wing will create it's lift less efficiently.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this wing shape the most efficient ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Only if you ask an aerodynamicist would the answer be yes. An elliptic wing will give you the best ratio of lift to drag, which clearly is one way to express efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, the wing has to lift itself plus a payload, but only lifting the payload should be considered when formulating efficiency. Therefore, pure lift/drag optimization is too narrow. What should count is the best ratio of lift minus wing weight relative to drag. R. T. Jones wrote a &lt;a href=&quot;http://digital.library.unt.edu/ark:/67531/metadc53315/m2/1/high_res_d/19760012005.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA Technical Note back in 1950&lt;/a&gt; in which he looked at this problem analytically. Wing weight goes up when much lift is created near the tips, because this lift will cause a disproportional root bending moment, and the wing spar which has to carry this bending moment is a significant part of the wing structure. Therefore, reducing lift at the tips and adding more lift at the root will create a lighter wing for a modest drag increase, resulting in an overall optimum for an almost triangular lift distribution. When compared to an elliptical wing planform, the total wing span of such an optimized wing is bigger for the same overall drag, but this wing will weigh less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eVl7h.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eVl7h.jpg&quot; alt=&quot;Spanwise loading comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spanwise loading comparison for wings of the same fixed lift, from NACA Technical Note 2249. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this is too easy. Scaling laws must be considered in addition. You know that elephants have much more massive legs relative to their body size than antelopes (or even ants, for an even more drastic comparison), since body mass scales with the cube of linear dimension while structural strength scales only with the square of linear dimension. This means that wing spar weight will be proportionally higher for larger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a consequence, insects have more elliptic wings than albatrosses, and model aircraft have optimum wings which are much more elliptic than the optimum wing of an airliner. The optimum shifts from an elliptic load distribution at very small scales to an almost triangular distribution at large scales.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-01-21T05:15:45.497" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24507" PostTypeId="1" CreationDate="2016-01-21T05:26:36.883" Score="70" ViewCount="9674" Body="&lt;p&gt;I came across this interesting factoid in another SE Aviation answer (&lt;a href=&quot;https://aviation.stackexchange.com/questions/11857/how-flat-does-a-runway-need-to-be/11866#11866&quot;&gt;How flat does a runway need to be?&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;seaplanes often use a curved takeoff run.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm trying to imagine why but cannot come up with a good reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know why?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="14897" LastEditDate="2019-12-26T16:00:47.940" LastActivityDate="2019-12-26T16:00:47.940" Title="Why would seaplanes use a curved takeoff run?" Tags="&lt;takeoff&gt;&lt;seaplane&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="24508" PostTypeId="2" ParentId="24507" CreationDate="2016-01-21T06:07:14.527" Score="13" Body="&lt;p&gt;The waves are running separate from the wind. When the plane has pick up enough out of the water it turns into the wind.&lt;/p&gt;&#xA;" OwnerDisplayName="user20435" LastActivityDate="2016-01-21T06:07:14.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24509" PostTypeId="2" ParentId="24507" CreationDate="2016-01-21T07:41:07.957" Score="131" Body="&lt;p&gt;Years ago now I gave a fair amount of instruction for seaplane ratings. I remember it quite fondly as seaplanes combine the fun of flying with aspects of the fun of boating. There were three conditions in which we used curved takeoff runs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most frequent curved takeoffs were on rivers, which tend to not run in a straight line, and even for those portions of a river that do, there may be rapids to stay clear of, so following the bend of a river or weaving between rapids was not unusual. In my case, the rivers were the McKenzie and Willamette, both in Oregon, USA. If you're ever in Eugene, Oregon, go down to &lt;a href=&quot;https://www.google.com/maps/@44.0598529,-123.0921624,1625m/data=!3m1!1e3&quot;&gt;Skinner's Butte Park on the Willamette River&lt;/a&gt;. On the upstream end of the park is the Ferry Street bridge. On the downstream end is the Washington-Jefferson bridge. In the 1970s we used to operate on the water between them, avoiding the rapids. We stored the airplane for a time on the Skinner's Butte Park shore line. That was legal and safe back then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next most frequent usage of curved takeoffs was to get off ponds that were not wide enough to allow a straight line takeoff. However, you can do it taking off in a curve along the perimeter of the pond. If you ever happen to fly over Daniels Field alongside Interstate 5 about 20 miles north of Eugene, Oregon, &lt;a href=&quot;https://www.google.com/maps/@44.2700137,-123.0617105,1148m/data=!3m1!1e3&quot;&gt;you'll see a lake/pond alongside the runway&lt;/a&gt; with a small island in the middle. There is no straight line you can draw on that pond that comfortably gives you room for takeoff, but you can circle the island and get into the air without difficulty.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The third circumstance we didn't have to use often was when we had to run across our own wake to be able to get up on the step on glassy water. For example, &lt;a href=&quot;https://en.wikipedia.org/wiki/Waldo_Lake&quot;&gt;Waldo Lake in the Oregon Cascades&lt;/a&gt; is at 5,400 feet elevation. A J-3 cub with an 85 horse engine and with two people on board simply cannot get up on the step when the surface of the lake is a dead calm. However, if you get going in a curved path, you can get up on the step when you run across your own wake. Once you're on the step, you can then put the airplane up on one float and get enough airspeed to take off. Just as a matter of information, seaplane operation on Waldo Lake is now prohibited.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="1931" LastEditDate="2016-01-24T14:15:40.950" LastActivityDate="2016-01-24T14:15:40.950" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24510" PostTypeId="1" AcceptedAnswerId="24528" CreationDate="2016-01-21T11:06:19.483" Score="5" ViewCount="898" Body="&lt;p&gt;I am decoding Compact Position Reporting (CPR) positions from ADS-B frames (the &lt;em&gt;airborne position&lt;/em&gt; and &lt;em&gt;surface position&lt;/em&gt; frames).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of my results give realistic longitude/latitude values, but some return things like 0,781518968485169 177,220642089844; or 1,76377118644068    -0,664306640625; or 2,12129237288136 -2,838134765625.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a feeling like I must be missing some kind of validation or some kind of frame type identification. Where can I find more information about the decoding process?&lt;/p&gt;&#xA;" OwnerUserId="13099" LastEditorUserId="62" LastEditDate="2016-01-21T13:07:20.997" LastActivityDate="2016-01-22T12:50:50.347" Title="How can I correctly decode CPR positions from ADS-B frames?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24511" PostTypeId="1" CreationDate="2016-01-21T12:26:37.150" Score="2" ViewCount="384" Body="&lt;p&gt;What is the plus sign found on some aircraft bodies?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first time I saw this sign was on a Robinson R44 helicopter. The &quot;plus sign&quot; was located below the right front door.&lt;/p&gt;&#xA;" OwnerUserId="13101" LastEditorUserId="12720" LastEditDate="2016-01-21T13:58:11.533" LastActivityDate="2016-01-21T13:58:11.533" Title="What would a &quot;Plus Sign&quot; marking be on aircraft fuselage?" Tags="&lt;aircraft-design&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-01-21T16:24:24.397" ContentLicense="CC BY-SA 3.0" />
  <row Id="24512" PostTypeId="2" ParentId="9101" CreationDate="2016-01-21T12:42:13.660" Score="8" Body="&lt;p&gt;This is an older question, and I have no answer, just experience:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When  I flew from Frankfurt (FRA) to Geneve (GVA) in January 2015, we were towed by a tug nearly all the taxiway to the runway. We turned to the parallel taxiway &quot;N north&quot; to get rid of the tug, then went back on taxiway &quot;N&quot; to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is our way as tracked by my mobile GPS:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iOC0x.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iOC0x.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot told us in advance that we will to this, and that it is some kind of experiment / project / study about if it works. (I guess more from logistics / operation side)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my data, I also have some time information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;12:12: End of push-back&lt;br&gt;&#xA;12:15: Leaving terminal&lt;br&gt;&#xA;12:21: turn right on &quot;N North&quot;&lt;br&gt;&#xA;12:22: get rid of tug, start engines&#xA;12:27: Start moving again, and back to  &quot;N&quot;&lt;br&gt;&#xA;12:29: arriving at runway&lt;br&gt;&#xA;12:31: accelerating  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I remember correctly, the engines were started when we were on &quot;N north&quot;, so 5-6 minutes before takeoff. However, we were taxiing to that place 20 without engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be interesting to know how much fuel could be saved by this procedure (It was a A320 or similar, I don't know), but at least, the aircraft didn't need any extra equipment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(And yes, it was an ordinary tug, not this electrical stuff or similar.)&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2016-01-21T12:42:13.660" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24513" PostTypeId="1" AcceptedAnswerId="24518" CreationDate="2016-01-21T16:20:18.983" Score="14" ViewCount="1373" Body="&lt;p&gt;In the picture below I noticed there are three circles or holes of some kind ahead of the wing, what are those?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/82GnD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/82GnD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.airliners.net/photo/Meridiana/McDonnell-Douglas-MD-82-DC-9-82/2251771&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="14897" LastEditDate="2018-03-12T15:13:35.457" LastActivityDate="2018-03-12T18:37:34.827" Title="What are the circles/holes ahead of the wing of an MD-82?" Tags="&lt;feature-identification&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24514" PostTypeId="2" ParentId="24474" CreationDate="2016-01-21T18:01:30.013" Score="-1" Body="&lt;p&gt;In theory, they are just transmitting data, not code updates to the aircraft. So, the worst-case scenario would be that somebody would replace a chart with fake chart or something like that, which would be a nuisance but should not affect the safety of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a matter of routine, &lt;em&gt;any&lt;/em&gt; radio link should be considered an inherently insecure mode of communication, because it is open, unlike wire connections which can be physically isolated and secured against intercept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if there is a bug or weakness in their system somewhere, it might be possible for a hacker to &quot;pierce the veil&quot; and somehow modify a live system. Whether that is possible or not depends entirely on the system architecture and implementation details of the software in question. Without knowing this (highly proprietary) information it is impossible to know whether such a weakness exists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The official guidance on practices is contained in various FAA circulars, notably FAA advisory circular (AC) 20-153.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a paper describing the general security situation: &lt;a href=&quot;http://www.cabaa.com/documents/FAA_Aircraft_System_Information_Security_Protection_Overview_4-1-2015_Jim_Skaves.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Aircraft Systems Security&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only the 787 is able to load actual flight system modules remotely, I believe, although as mentioned above many aircraft can wirelessly retrieve flight bag info. How Boeing verifies that a module is valid before loading I do not know, but in all likelihood they use a cryptographic certificate. If this is the case, then a hacker would either have to steal the cryptographic keys from Boeing, or find a bug in how they were using the certificate, in able to introduce a false module to the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-01-21T18:52:02.117" LastActivityDate="2016-01-21T18:52:02.117" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24517" PostTypeId="1" CreationDate="2016-01-21T19:00:21.113" Score="4" ViewCount="12595" Body="&lt;p&gt;How to calculate in the right way the efficiency of a propeller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we know the engine power, speed of the plane and the thrust of its propeller, what is the correct method, (1) or (2), for calculating the efficiency of the propeller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vcgpZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vcgpZ.png&quot; alt=&quot;Efficiency of a propeller&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that Method 1 is the correct one, it appears that the efficiency of a propeller must satisfy the inequality:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KFoeq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KFoeq.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like Method 1 is correct and 2 is wrong as long as the page &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Performance of Propellers, MIT&lt;/a&gt; calculates the efficiency on an ideal propeller and gets the same inequality.&#xA;If a propeller of diameter, d, delivers the thrust, T, while the plane travels at the speed, V, it always has a maximum possible efficiency that can be calculated, is below 1 and can not be improved. &lt;strong&gt;Not even an ideal propeller of diameter, d, has, in general, an efficiency that reaches 100%&lt;/strong&gt;. The absolute minimum, reference power, is always $TV$ and not something else and the efficiency is always:&#xA;$$TV/Power_{absorbed}$$&#xA;where the minimum absorbed power is calculated with Froude's Propeller Theory. &lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="7568" LastEditDate="2016-07-19T04:12:56.980" LastActivityDate="2021-03-15T20:26:27.913" Title="What is the correct formula to calculate propeller efficiency?" Tags="&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24518" PostTypeId="2" ParentId="24513" CreationDate="2016-01-21T19:26:07.770" Score="20" Body="&lt;p&gt;The three large circles indicated in the question are &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot-static_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;static port&lt;/a&gt; plates. These measure the &lt;a href=&quot;https://en.wikipedia.org/wiki/Static_pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;static pressure&lt;/a&gt; of the surrounding air, which is used to measure airspeed and &lt;a href=&quot;https://aviation.stackexchange.com/q/14789/1696&quot;&gt;altitude&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qosta.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qosta.jpg&quot; alt=&quot;MD-80 Decal set with static ports labeled&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.internetmodeler.com/2000/december/new-releases/drawdecal_md80windows.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Original Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to &lt;a href=&quot;http://www.hilmerby.com/photo/md80/photom8.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;a link&lt;/a&gt; from Jonathan Walters, here is a closeup of one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HtVNC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HtVNC.jpg&quot; alt=&quot;Static port closeup&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The four smaller areas in a row along the centerline are the &lt;a href=&quot;http://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;nofollow noreferrer&quot;&gt;radar altimeter&lt;/a&gt; transmitters/receivers. The radar altimeter uses radio waves to determine the aircraft's altitude above the ground. This diagram for the A345 has them further aft, they're in similar configurations on &lt;a href=&quot;https://aviation.stackexchange.com/a/21514/1696&quot;&gt;other aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vs5BD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vs5BD.png&quot; alt=&quot;A345 antenna locations with radar altimeters circled&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.pprune.org/rumours-news/418896-bad-rwy-jfk-again-3.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Original Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="14897" LastEditDate="2018-03-12T18:37:34.827" LastActivityDate="2018-03-12T18:37:34.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24519" PostTypeId="2" ParentId="24507" CreationDate="2016-01-21T21:07:06.997" Score="26" Body="&lt;p&gt;One reason for a curved takeoff is the &lt;em&gt;downwind arc&lt;/em&gt; method as described on page 4-14 of the FAA Seaplane, Skiplane, and Float/Ski Equipped Helicopter Operations Handbook (FAA-H-8083-23):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DOWNWIND ARC&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The other crosswind takeoff technique results in a&#xA;  curved path across the water, starting somewhat into the&#xA;  wind and turning gradually downwind during the takeoff&#xA;  run. This reduces the actual crosswind component at the&#xA;  beginning of the takeoff, when the seaplane is most susceptible&#xA;  to weathervaning. As the aerodynamic controls&#xA;  become more effective, the pilot balances the side loads&#xA;  imposed by the wind with the skidding force of an intentional&#xA;  turn, as always, holding the upwind wing down&#xA;  with the ailerons. [Figure 4-17]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The pilot plans a curved path and follows this arc to&#xA;  produce sufficient centrifugal force so that the seaplane&#xA;  tends to lean outward against the wind force. During&#xA;  the run, the pilot can adjust the rate of turn by varying&#xA;  rudder pressure, thereby increasing or decreasing the&#xA;  centrifugal force to compensate for a changing wind&#xA;  force. In practice, it is quite simple to plan sufficient&#xA;  curvature of the takeoff path to cancel out strong&#xA;  crosswinds, even on very narrow rivers. Note that the tightest part of the downwind arc is when the seaplane is traveling at slower speeds.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uCH3w.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uCH3w.jpg&quot; alt=&quot;downwindarc.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-01-21T21:50:58.057" LastActivityDate="2016-01-21T21:50:58.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24520" PostTypeId="1" AcceptedAnswerId="24522" CreationDate="2016-01-21T22:35:12.857" Score="0" ViewCount="374" Body="&lt;p&gt;After &lt;a href=&quot;https://en.wikipedia.org/wiki/British_European_Airways_Flight_548&quot; rel=&quot;nofollow&quot;&gt;BEA Flight 548 incident&lt;/a&gt; in June 1972, all British-registered airliners have mandatory cockpit voice recorders. The TV series &lt;a href=&quot;https://en.wikipedia.org/wiki/Mayday_(TV_series)&quot; rel=&quot;nofollow&quot;&gt;Mayday&lt;/a&gt; claimed no voice recorders were installed in Hawker Tridents before the report of the incident was released.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;9 months before BEA Flight 548, a Chinese Air Force Trident 1E (AP-ATL) crashed in Mongolia. Lin Biao, the second-in-charge in China, was killed as well as his family members in the incident. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident itself is still mysterious, but some source claimed that there were voice recorders in the cockpit and the chat inside the plane was recorded.  Many sources cited that the Chinese officers did not know the black box was installed, so the voice recorder was only installed by either Pakistan International Airlines (previous owner of the airliner) or by the manufacturer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is : Were there any Hawker Trident installed cockpit voice recorder before BEA Flight 548 incident?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="595" LastEditDate="2016-01-22T01:15:40.537" LastActivityDate="2016-01-22T01:18:33.020" Title="Was there any Hawker Trident installed cockpit voice recorder before BEA Flight 548 incident?" Tags="&lt;airliner&gt;&lt;cockpit-voice-recorder&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24521" PostTypeId="2" ParentId="24489" CreationDate="2016-01-21T23:21:07.290" Score="19" Body="&lt;p&gt;You are right, there are few modern aerodiesels around - so few in fact that we can go through the brief list one by one:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thielert_Centurion&quot; rel=&quot;nofollow noreferrer&quot;&gt;Thielert&lt;/a&gt;:&lt;/strong&gt; This is a development based on Mercedes-Benz car diesels, of which more than 1500 1.7 liter engines were built. Currently, a 2.0 liter engine is offered. The original Thielert company went bankrupt in 2008 and has been taken over by Continental.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Austro_Engine_E4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Austro-Engine&lt;/a&gt;&lt;/strong&gt;, another conversion of a car diesel for aircraft use. It is the result of the disappointment of Thielert's main customer, Diamond Aircraft, with the record of Thielert's initial Centurion 1.7 engine.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/SMA_SR305-230&quot; rel=&quot;nofollow noreferrer&quot;&gt;SMA&lt;/a&gt;:&lt;/strong&gt;, a French turbocharged diesel with 5 liters displacement. Currently, around 100 of them have been delivered after almost 20 years of development work.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Zoche_aero-diesel&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zoche&lt;/a&gt;:&lt;/strong&gt; The product of a father-son team with &lt;a href=&quot;http://www.zoche.de/zoche_brochure.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;many clever details&lt;/a&gt;, but a quarter century of development work has not yet resulted in an airworthiness certificate for their two-stroke radial diesels. While Zoche claims to be the victim of a conspiracy by the authorities, the accused complain that the engines could not keep their cylinder heads on for long enough.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;What has held the diesels back for so long?&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Cost:&lt;/strong&gt; Development in aviation piston engines has effectively stopped with the jet age. The existing designs were simply good enough until fuel prices went through the roof. This made diesels only attractive in niches, and as a consequence, production runs were far too small to justify the major development effort. Aviation engines &lt;a href=&quot;https://aviation.stackexchange.com/questions/11527/what-are-some-of-the-differences-between-piston-engines-used-in-aircraft-and-aut/11531?s=1%7C0.1669#11531&quot;&gt;run constantly at around 70% of their full power&lt;/a&gt;, so regular car engines could not be used without heavy modifications. As a consequence, &lt;a href=&quot;http://www.aero-news.net/index.cfm?do=video.playVideo&amp;amp;videoid=5b19009d-30ec-4d65-a87b-9478ef8cc00e&quot; rel=&quot;nofollow noreferrer&quot;&gt;a conversion kit can cost you $89,000&lt;/a&gt;!&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Weight and complexity:&lt;/strong&gt; The higher compression ratio of 1:30 requires a heavier structure, and fuel injection, a gearbox and turbocharging push the part count well above that of a gasoline engine. Once you compare system mass (fuel plus engine), the diesel wins only at ranges which are now mostly flown by jets. Yes, fuel flow is less (10 gallons per hour for a diesel against 13.5 gallons per hour for a comparable gasoline engine), but will only help at ranges above a couple of hundred miles.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Vibration!&lt;/strong&gt; With that compression ratio, every ignition causes a three or four times heavier jolt to the engine and the aircraft structure. Not only the engine, but the whole aircraft structure needs to be designed with that in mind.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To be fair, a modern gasoline engine will also benefit from fuel injection, a gearbox and turbocharging, and Zoche initially did not use an electric system, relying instead on pressurized air for starting the engine (a pressure bottle loses much less of its stored energy when cooled to -20° than a battery, after all), but the practical aerodiesels are a lot more complex than the engines they are meant to replace, creating an obvious reliability disadvantage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wIX7B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wIX7B.jpg&quot; alt=&quot;Thielert Centurion 1.7 in a Diamond Twin Star&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thielert Centurion 1.7 in a Diamond Twin Star (picture &lt;a href=&quot;https://en.wikipedia.org/wiki/Thielert_Centurion#/media/File:DiamondDA-42TwinStarN131TSThielertEngineDetail.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-03-08T14:14:45.770" LastActivityDate="2018-03-08T14:14:45.770" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24522" PostTypeId="2" ParentId="24520" CreationDate="2016-01-22T01:09:12.650" Score="3" Body="&lt;p&gt;It doesn't appear that CVRs were installed in any Tridents before the BAE 548 accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/GB/1972-06-18-UK.pdf&quot; rel=&quot;nofollow&quot;&gt;accident report&lt;/a&gt; noted that CVRs are installed in some British Aircraft, but stays silent on the Tridents:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This, at least as far as CVRs is concerned, we do not regard as&#xA;  satisfactory. ... They are fitted as standard equipment to all BOAC's 747s and most large United States transport aircraft. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If &lt;em&gt;any&lt;/em&gt; of the Tridents had CVRs, the report would've surely mentioned it. The Chinese Tridents didn't appear to have CVRs long after the accident. In fact, the &lt;a href=&quot;http://ebook.lib.hku.hk/HKG/B35835655.pdf&quot; rel=&quot;nofollow&quot;&gt;accident report of a Trident 2E in 1988&lt;/a&gt; notes,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The  aircraft  was not equipped, neither was it required to be equipped, with a cockpit voice recorder (CVR).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on these, it does not appear that any Tridents were fitted with CVRs before the accident.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="12720" LastEditDate="2016-01-22T01:18:33.020" LastActivityDate="2016-01-22T01:18:33.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24523" PostTypeId="1" CreationDate="2016-01-22T01:16:48.357" Score="8" ViewCount="448" Body="&lt;p&gt;When I was at the airport a month ago I spotted a McDonnell MD-80 and took a picture of it and was very interested in this historic aircraft. I looked up the specs and this is what turned up. The MD-81,82,83, and 88 models all have the same fuselage length(147ft 8in) except for the 87 model(130ft 4in). They all have the same wingspan at 107ft 8in and the 81,82,83,88 carry 172 on a one class cabin except for the 87 which carries 139 on a one class cabin. So is there any way to tell the difference between the 81,82,83, and 88 models?&lt;a href=&quot;https://i.stack.imgur.com/rYoJ4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rYoJ4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; The picture I took of the MD-80?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="19" LastEditDate="2016-04-20T16:49:37.417" LastActivityDate="2016-04-20T16:49:37.417" Title="Is there any way to tell the difference between MD-80 models?" Tags="&lt;aircraft-identification&gt;&lt;md-80&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24524" PostTypeId="2" ParentId="24523" CreationDate="2016-01-22T02:46:22.707" Score="3" Body="&lt;p&gt;For Delta, it's either an MD-88, or an MD-82 reconfigured as an MD-88. The differences between the 81/82/83/88 are engine, fuel, and flight deck options. MD-87 is visually shorter than the others.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-01-22T02:46:22.707" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24525" PostTypeId="1" CreationDate="2016-01-22T03:17:58.987" Score="8" ViewCount="1250" Body="&lt;p&gt;Let's say we have a propeller-driven aircraft in the pusher configuration (rear-facing propellers). If we could somehow put an engine at the wing tip (ignoring structural concerns), and maybe make the propeller rotate in the opposite direction of the way the wing-tip vortex wants to spin, would this eliminate or at least drastically reduce the wing-tip vortex?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2019-08-07T20:07:56.410" Title="Can wing-tip vortices be reduced/eliminated with a rear-facing propeller near the wing-tip?" Tags="&lt;aerodynamics&gt;&lt;engine&gt;&lt;wing-tip-vortex&gt;" AnswerCount="4" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24526" PostTypeId="1" AcceptedAnswerId="24527" CreationDate="2016-01-22T05:47:16.470" Score="23" ViewCount="3827" Body="&lt;p&gt;One of the main problems with water landings is that you need a bigger engine to counter the various drags caused by the pontoons. The specific case of &lt;a href=&quot;https://aviation.stackexchange.com/questions/24507/why-would-seaplanes-use-a-curved-takeoff-run#comment57225_24509&quot;&gt;&quot;run[ing] across our own wake to be able to get up on the step on glassy water&quot;&lt;/a&gt; brings some interesting thoughts.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[B]asically a floatplane has to break the suction of the water - kind of like pulling your boot out of mud - and if the water isn't moving at all then it has to do that all by itself. If there are some waves, or a wake, or any kind of discontinuity in the water, then that gives the aircraft the momentary break it needs to overcome that initial suction. &quot;The step&quot; in this context refers to the step-up shape you see partway down the float (or hull); when you're &quot;on the step&quot; then you're using the part of the float forward of that step to hydroplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is well known that water's significantly higher density makes high speeds difficult. A solution to that problem is the hydrofoil - a small underwater wing that raises some or all of a boat's hull out of water to reduce friction and increase speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here is my dumb question: would placing a hydrofoil under a pontoon save fuel on takeoff? And how likely would the increased drag during flight cancel that advantage on a typical flight?&lt;/p&gt;&#xA;" OwnerUserId="2910" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2020-06-15T16:37:52.340" Title="Has anyone considered putting a hydrofoil on a sea plane?" Tags="&lt;seaplane&gt;" AnswerCount="4" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="24527" PostTypeId="2" ParentId="24526" CreationDate="2016-01-22T07:23:36.373" Score="29" Body="&lt;p&gt;Yes. I mean, sort of. Nobody's ever built a production hydrofoilplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not a bad idea, but seaplanes are &lt;a href=&quot;https://aviation.stackexchange.com/q/1857/39&quot;&gt;a relatively niche product&lt;/a&gt; these days and there doesn't seem to be a lot of innovation in the field. Back when there was, there was innovation &lt;em&gt;everywhere&lt;/em&gt; so the idea of hydrofoils didn't stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F2Y_Sea_Dart&quot; rel=&quot;noreferrer&quot;&gt;Convair F2Y Sea Dart&lt;/a&gt;, a 1950s prototype jet-powered fighter, used two 'hydro-skis' for takeoff and landing. It was more or less awful compared to the crop of land-based aircraft coming along and after a prototype disintegrated they (probably wisely) chose to shut the program down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F2Y_Sea_Dart#/media/File:F2Y_Sea_Dart_2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SOa3zm.jpg&quot; alt=&quot;https://en.wikipedia.org/wiki/Convair_F2Y_Sea_Dart#/media/File:F2Y_Sea_Dart_2.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some &lt;a href=&quot;https://en.wikipedia.org/wiki/Category:Hydrofoil_aircraft&quot; rel=&quot;noreferrer&quot;&gt;other prototype aircraft that used actual hydrofoils&lt;/a&gt; that I found after some &lt;a href=&quot;https://www.google.com/search?q=hydrofoil+aircraft&quot; rel=&quot;noreferrer&quot;&gt;quick googling&lt;/a&gt;. A company called Lisa Airplanes seems to have an LSA - the &lt;a href=&quot;http://www.lisa-airplanes.com/en/akoya/ultra-versatile-lsa-airplane/amphibious-aircraft.html&quot; rel=&quot;noreferrer&quot;&gt;Akoya&lt;/a&gt; - that's under development using tech similar to the Sea Dart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 1929 &lt;a href=&quot;https://en.wikipedia.org/wiki/Piaggio_P.7&quot; rel=&quot;noreferrer&quot;&gt;Piaggio P.7&lt;/a&gt; used hydrofoils, and was intended to compete for the Schneider Trophy, but never made it airborne. Interestingly enough it had a screw (marine propeller) at the tail and a proper aviation propeller up front, and the pilot would've had to do some juggling between the two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Piaggio_P.7#/media/File:Piaggio_Pegna_P.C.7_3-view.svg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dkYS3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's likely there were others, but I'm running low on sleep.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-01-22T07:45:11.923" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24528" PostTypeId="2" ParentId="24510" CreationDate="2016-01-22T10:15:36.563" Score="2" Body="&lt;p&gt;We were decoding Airborne Position frames having TypeCode &lt;code&gt;0&lt;/code&gt;, &lt;code&gt;9-18&lt;/code&gt; and &lt;code&gt;20-22&lt;/code&gt;.&#xA;Apparently, frames with TypeCode &lt;code&gt;20-22&lt;/code&gt; and possibly &lt;code&gt;0&lt;/code&gt; have to be decode a different way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(For now I think that I get enough information out of TypeCode &lt;code&gt;9-18&lt;/code&gt; frames so I'll just skip the other ones.)&lt;/p&gt;&#xA;" OwnerUserId="13099" LastEditorUserId="13099" LastEditDate="2016-01-22T12:50:50.347" LastActivityDate="2016-01-22T12:50:50.347" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24529" PostTypeId="2" ParentId="24525" CreationDate="2016-01-22T10:21:45.873" Score="6" Body="&lt;p&gt;Eliminate, no. The wingtip vortices &lt;strong&gt;are inherent part of lift generation&lt;/strong&gt;. There is &lt;strong&gt;no lift without wingtip vortices&lt;/strong&gt;. The wake vortices are carrying the momentum that was given to the air to produce the lift, and to cancel them, you'd have to give the air the opposite momentum, which would negate the produced lift. See &#xA;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence&quot;&gt;How does an aircraft form wake turbulence?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Improve efficiency, yes, a little bit. The propellers would cause downwash in their span outside of the wing tips, effectively extending the wing span and longer wing span means, slightly, less induced drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, such design would have extremely poor single-engine handling, not only because the thrust would become very asymmetric, but also because the lift would partially depend on the engines and therefore the side with stopped engine would also loose some lift, and deflecting aileron to compensate would generate more drag to make the thrust even more asymmetric. And it would have poor all-engine-out performance too due to the loss of lift. Does not sound like optimal approach when similar benefits can be obtained without all these problems by using longer wings.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2019-08-07T10:53:50.070" LastActivityDate="2019-08-07T10:53:50.070" CommentCount="31" ContentLicense="CC BY-SA 4.0" />
  <row Id="24530" PostTypeId="1" AcceptedAnswerId="24532" CreationDate="2016-01-22T11:15:30.127" Score="23" ViewCount="3810" Body="&lt;p&gt;Some land-based fighter aircraft have a drogue-chute to help them slow down during landing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do any current models of commercial aircraft have a similar&#xA;mechanism?&lt;/li&gt;&#xA;&lt;li&gt;Secondly, would such a mechanism help aircraft in making a better landing and reduce landing related incidents/ accidents?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="12220" LastEditDate="2016-01-22T17:19:15.267" LastActivityDate="2016-01-23T16:34:34.080" Title="Do any commercial airline models have a parachute at rear to help in landings?" Tags="&lt;parachute&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24532" PostTypeId="2" ParentId="24530" CreationDate="2016-01-22T13:36:23.100" Score="27" Body="&lt;p&gt;It is called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Drogue_parachute&quot;&gt;drogue parachute&lt;/a&gt; and I don't think that any of the present generation large commercial aircraft use them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, a number of older commercial aircraft have used them, a good example being the Sud Caravelle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vQgzK.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vQgzK.jpg&quot; alt=&quot;Caravelle drogue&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from eu.airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some issues with using drogue chutes in a commercial airliner, which would limit their effectiveness.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Most commercial airliners have thrust reversers already.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For it to be effective, the parachute has to be quite huge. For example, the Handley Page Victor, which had MTOW in the range of A320, had a drogue chute 48' (or 14.6m) in diameter. The chute would occupy volume and increase weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If drogue chutes are used, they have to be packed before every flight, which will increase turnaround times. Another option is to replace them at the end of every deployment, which would increase costs.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Deployment failure/partial deployment/Uncommanded deployment will affect the safety of the flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The need to use a drogue chute can limit the crosswind landing of the airliner significantly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aircraft dragging a huge chute during taxiing back to the ramp is not a good idea from FoD point of view.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9411" LastEditDate="2016-01-22T19:21:07.867" LastActivityDate="2016-01-22T19:21:07.867" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24533" PostTypeId="1" CreationDate="2016-01-22T13:49:03.063" Score="8" ViewCount="485" Body="&lt;p&gt;I recently found the following image showing the different sources of noise in vehicles. I notice that Aerodynamics is actually quite a big part of vehicle noise, as shown below by the blue line:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j97xm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j97xm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.528.2123&amp;amp;rep=rep1&amp;amp;type=pdf&quot; rel=&quot;noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can imagine this is partly because of the flow going over the car. However, I think a part of this noise also comes from separating flows (for example at the rear window).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering if it is possible to reduce the aerodynamic noise of vehicles by applying separation control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As such, I'm wondering:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How much noise does a separating flow generate?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm guessing this highly specific to the local geometry and velocity, but I would already be very happy with some examples.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="6979" LastEditDate="2016-01-22T21:38:43.183" LastActivityDate="2016-08-22T20:15:17.763" Title="How much noise does flow separation cause?" Tags="&lt;noise&gt;&lt;separation&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24534" PostTypeId="2" ParentId="24447" CreationDate="2016-01-22T14:15:54.917" Score="5" Body="&lt;p&gt;While it's impossible for anyone to know for sure it's unlikely he would have had much idea at all of where he was. According to the articles I have read when he jumped it was at night, in heavy rain, and the ground was obscured by cloud cover. The visibility was bad enough that neither of the F-106 pilots which were trailing the airplane saw him jump from the airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;He did not direct a specific course, what was agreed was that they would fly to reno to refuel, and then to Mexico. The gear was to be extended and the flaps at 15 degrees, so they could not fly that fast. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots and flight attendant were in the cockpit with the door closed, all Cooper would have had for reference is the outside windows and the view out the back, plus any instruments he brought with him. He didn't have a current weather brief, so no knowledge of the winds aloft and how that would affect ground speed. Given the conditions he would not have been able to see much out of the window at all. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have to consider human factors as well. The flight was at 10,000ft, unpressurized, and Cooper had been under stress without rest for hours. He had been drinking moderate amounts of alcohol intermittently. All this would have degraded his ability to determine location. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lack of ground speed data, and exact course meant he would only have a vague idea of his track over the ground, and the poor weather and darkness would have prevented him from using landmarks. He would have had an approximate idea of where he was - somewhere between Seattle and Portland, but other than that he was literally in the dark. He may have spotted the glow of lights from a town and made his move, or he may have deliberately jumped in an empty area to escape. I don't think we will ever know. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-01-22T14:15:54.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24535" PostTypeId="2" ParentId="16012" CreationDate="2016-01-22T19:07:14.780" Score="1" Body="&lt;p&gt;The Certificate of Airworthiness may be invalidated with an external attachment to the aircraft.  The aircraft operator will need to inquire to the CAA what applies for the type in question.  This is the operators best course of action to get an answer on airworthiness questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However it may just require pilot approval, but it depends, there are however precedence in photography fields already pertaining to external fasteners and equipment. But contacting the CAA is the best way to clear this up.&lt;/p&gt;&#xA;" OwnerUserId="8375" LastEditorUserId="12288" LastEditDate="2016-04-07T10:27:45.320" LastActivityDate="2016-04-07T10:27:45.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24536" PostTypeId="1" AcceptedAnswerId="24537" CreationDate="2016-01-22T20:54:52.217" Score="10" ViewCount="10913" Body="&lt;p&gt;I'm planning on building a small model turbofan engine for a bit of fun but I thought I'd better get a better understanding of how they work first. I understand the majority of it at the moment but I'm struggling to see what the bypass air actually does, to my mind it seems like a waste of air and energy if its just going straight out of the engine without compression...could someone explain this to me?&lt;/p&gt;&#xA;" OwnerUserId="13120" LastEditorUserId="13120" LastEditDate="2016-01-23T00:03:35.603" LastActivityDate="2018-09-23T15:20:19.293" Title="What is the bypass air in a turbofan engine actually for?" Tags="&lt;turbofan&gt;&lt;bypass-ratio&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24537" PostTypeId="2" ParentId="24536" CreationDate="2016-01-22T21:28:16.063" Score="19" Body="&lt;p&gt;On modern turbojets the bypass air provides (at least) two things &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Thrust&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air does bypass the engine core, but it is accelerated by the N1 fan and provides thrust as it is expelled rearward out of the engine.  Thrust from the bypass air can contribute more than half of the total thrust produced by the engine (upwards of 80% of the total thrust for some engines in certain phases of flight).  Part of the reason the bypass air is so efficient is that much energy is extracted from the core exhaust to spin the high and low pressure turbines (dual spool) that drive the N1 fan and the N2 compressor stages.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine cooling and noise reduction&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cool bypass air can be mixed with the hot air that went through the core at the rear of the engine.  This mixing cools the engine exhaust and reduces the jet engine noise resulting from the rapid expansion of that air once it leaves the engine.  The cool bypass air flowing around the engine core can also be used for general engine cooling.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-22T21:28:16.063" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24538" PostTypeId="2" ParentId="24536" CreationDate="2016-01-22T21:33:29.253" Score="5" Body="&lt;p&gt;The bypass air is actually what gives the jet engine most of its thrust. As the air enters the engine, some of it goes to the turbine core and runs the whole engine. But most of the air goes through and is sped up by the large fan giving it the thrust. Doing it this way increases the efficiency because the engine moves more air, although at a slightly lower velocity, than just a low-bypass engine which moves some air with high velocity.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-22T21:33:29.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24539" PostTypeId="2" ParentId="24536" CreationDate="2016-01-22T21:36:25.047" Score="2" Body="&lt;p&gt;Essentially, it is more efficient from a propulsion point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me explain this with a very simple example. Imagine that you are over a skateboard and you would like to propulse yourself using your hands to give yourself the boost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have 2 options, either you use your hands over another person over an skateboard or you impulse yourself using a heavy desk?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you will imagine, if you use the other guy with the skateboard he will go in the other direction with a similar speed, and the desk will be moved slightly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But... it is clear in your mind that is more efficient to use the desk, moreover, you will prefer to use a wall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is happening?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are trying to impulse yourself (third Newton's law) you create the same force on the other side, but when using a bigger and heavier body that body will go slower. Essentially is more efficient to &quot;propulse&quot; using a heavier mass at lower speed that a lighter mass at higher speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is exactly the same principle that you use in water, when you use diving fins you get faster speeds as you are moving your legs slower but moving a bigger amount of water, exactly like the skateboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same principle applies to turbofans instead of water they use air. Instead of diving fins they use blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By creating a bypass they use also the air going through the bypass to get propulsion. Is more efficient than having a single core at very high speed.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2016-01-22T21:36:25.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24540" PostTypeId="2" ParentId="24533" CreationDate="2016-01-22T21:51:57.087" Score="0" Body="&lt;p&gt;There are several sources of noise and a complete theory explaining how the noise is created. There are several mechanisms working in a car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One mechanism appears when you have, as you mention, detached flow. When a flow is detached the flow structures after the detachment point is similar to the following one:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/G6afe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G6afe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see the air behaves creating swirls. Those swirls interact between each other and generating noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if you are able to avoid the creation of the swirls you are able as well to reduce the noise generated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually avoiding the creation of swirls and detachment is not the only mechanism, you can always &quot;create different swirls&quot; that generate smaller noise. For example, the antennas are not perfect cilinders and end like a cilinder with an string around in order to generate a different detachment structure, in this case to avoid vibration due to specific tones, this change of structure will also change the noise generate and I think (I can not say for sure) in this case reduces the noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2023j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2023j.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2016-01-22T21:51:57.087" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24541" PostTypeId="2" ParentId="24530" CreationDate="2016-01-22T21:53:58.350" Score="6" Body="&lt;p&gt;With the improvement of the brakes and reverse thrust, parachutes are no longer an option for airlines. Nowadays the carbon brakes are the best brakes in the aviation market, together with auto brakes, reversers and speed brakes, most of the new generation aircrafts are landing much shorter compared with old generations, the reject takeoff is almost automatic and with the correct calculation the runway overrun accidents are decreasing considerably. As the effectiveness of the thrust reversers are better at high speed, most of the airlines uses reverser thrust in idle, the pilots are suggested in case of using other than idle reversers, to apply reverser thrust until 80 knots or 60 kts after landing, auto brakes combined with Carbon Brakes and a speed brake, give to the aircraft shorter stop distance than before. The brake temperature is much better in carbon brakes, hot temperatures are still a problem in case of reject takeoff but for long taxis is no longer a problem. So parachutes are retired in commercial aviation. Hope this explanation helps. ;)&lt;/p&gt;&#xA;" OwnerUserId="13121" LastActivityDate="2016-01-22T21:53:58.350" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24542" PostTypeId="1" AcceptedAnswerId="24552" CreationDate="2016-01-22T23:18:18.873" Score="8" ViewCount="1478" Body="&lt;p&gt;I watched this &lt;a href=&quot;https://www.youtube.com/watch?v=hyaIrhGrCzo&quot;&gt;video&lt;/a&gt; of the Raytheon SDB II and noticed that it seems to have no control surfaces on its wings, just the four fins on the tail. How do these fins work to alter the attitude of the SDB and other missiles or aircraft using the same scheme? For example, if it were to pitch downwards, which fins would need to move and in which direction?&lt;/p&gt;&#xA;" OwnerUserId="13126" LastActivityDate="2016-01-23T17:09:59.677" Title="How do X-shaped control surfaces work?" Tags="&lt;missiles&gt;&lt;control-surfaces&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24543" PostTypeId="2" ParentId="24536" CreationDate="2016-01-23T01:01:08.433" Score="9" Body="&lt;p&gt;An airplane engine provides thrust by accelerating air (plus some combustion products) backwards. As air is accelerated backwards the plane is accelerated forward thanks to conservation of momentum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Momentum is proportional to velocity but kinetic energy is proportional to velocity squared. The result of this is that it is notionally more efficient to accelerate a larger amount of air to a low speed than a smaller amount to a higher speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice this is complicated by the fact that the air is already moving relative to the airplane. It is difficult to efficently add a small ammount of extra speed to already fast-moving air. So the best exhaust velocity depends on the speed at which the airplane will fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The exhaust velocity of a gas turbine core is higher than is desirable for most airplanes. So a turbine and fan are used to capture energy from the exhaust gasses and use them to accelerate bypass air resulting in a turbofan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For planes that spend a lot of time at low speeds, designers may use a gearbox and propeller instead of the fan resulting in a turboprop.&lt;/p&gt;&#xA;" OwnerUserId="11774" LastEditorUserId="11774" LastEditDate="2017-02-06T11:40:25.800" LastActivityDate="2017-02-06T11:40:25.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24544" PostTypeId="1" AcceptedAnswerId="31784" CreationDate="2016-01-23T01:08:16.500" Score="7" ViewCount="382" Body="&lt;p&gt;Once inside the jet stream altitude 7-15 km is it all that turbulent or is there a way to enter it smoothly for an ultralight plane or a powered glider? &lt;a href=&quot;https://aviation.stackexchange.com/questions/24420/can-a-giant-kite-carrying-a-person-fly-around-the-world-by-riding-jet-streams&quot;&gt;More info&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user20435" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-09-24T23:41:12.077" Title="Is there a way for an ultralight or powered glider to smoothly enter a jet stream?" Tags="&lt;approach&gt;&lt;glider&gt;&lt;experimental-aircraft&gt;&lt;ultralight&gt;&lt;windshear&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24545" PostTypeId="2" ParentId="24542" CreationDate="2016-01-23T01:15:36.600" Score="3" Body="&lt;p&gt;The Raytheon SDB (Small Diameter Bomb) has four fins at the rear end for control of the bomb during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NsULX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NsULX.jpg&quot; alt=&quot;SDB&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from defenseindustrydaily.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic operation of the fins for control is similar to the aircraft control surfaces like the stabilizer. The fins are located way from the cg so that any change in their lift will cause a moment at the cg, helping in changing the missile orientation. For example, for turning the misile, the top and bottom fins are rotated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MsDVI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MsDVI.png&quot; alt=&quot;Rotate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Principles of Guided Missiles and Nuclear Weapons&lt;/em&gt; by USN&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, in case of SDB, the entire fin rotates rather than a part, but the principle is the same. For pitching up and down, the fins on either side are rotated (rotate up for pitch down and rotate down for pitch up).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a7bYW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a7bYW.png&quot; alt=&quot;Pitch&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Principles of Guided Missiles and Nuclear Weapons&lt;/em&gt; by USN&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A number of missiles have 'X' shaped control surfaces so as to mount on the aircraft rails so that they extend on either side of the rail. The operation is similar to what is outlined above- the deflection (rotation) of the control surfaces create pitching moment about the cg. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For 'X' shaped control surfaces, the rotation of control fins cause forces in both the horizontal and vertical axes (as opposed to the '+' shaped ones, where only two can be rotated for creating a pitching moment in one plane); Here, if all the control fins are rotated by same angle, the horizontal components cancel each other and the vertical component causes the missile (SDB) to pitch. For yaw, the surfaces are rotated in opposite directions, resulting in the vertical component being cancelled, and the horizontal components causing yaw.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-01-23T17:09:59.677" LastActivityDate="2016-01-23T17:09:59.677" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24547" PostTypeId="2" ParentId="1397" CreationDate="2016-01-23T03:51:27.353" Score="0" Body="&lt;p&gt;For tail side-mounted: I think there are issues with airflow to engines at certain angles, reducing stall-recovery options.&lt;/p&gt;&#xA;" OwnerUserId="13128" LastActivityDate="2016-01-23T03:51:27.353" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24548" PostTypeId="1" CreationDate="2016-01-23T12:25:28.750" Score="6" ViewCount="3101" Body="&lt;p&gt;The FAA IFR Landing Minima Chart has both ceiling and visibility minima regardless of approach type (straight-in or circling). I believe it means that a pilot should meet the both ceiling and visibility minima although he conducts straight-in approach procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in my country (not USA, we follow ICAO regulations), landing minima for straight-in approach procedure consists of only 'visibility'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I guess there is difference on landing minima between ICAO and FAA. But I couldn't find that information. &lt;/p&gt;&#xA;" OwnerUserId="12972" LastEditorUserId="5517" LastEditDate="2017-06-15T11:54:11.023" LastActivityDate="2018-03-23T11:25:06.190" Title="Is there any difference in landing minima between ICAO and FAA?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24549" PostTypeId="1" AcceptedAnswerId="24551" CreationDate="2016-01-23T13:18:59.177" Score="8" ViewCount="1899" Body="&lt;p&gt;Are there examples of propellers tilted in a controlled way to help in attitude control for pitch and yaw, adding a torque component?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/COVex.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/COVex.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Tilted propeller assumption&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This would be similar to thrust vectoring in jets.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/e4I5M.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e4I5M.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Vectored thrust principle&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively could a swashplate similar to the one used in helicopter main rotor be used to generate asymmetric thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I think this excludes &lt;a href=&quot;https://en.wikipedia.org/wiki/Convertiplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;convertiplanes&lt;/a&gt; where the propellers are converted into rotors to take-off, land or move vertically.)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-01-23T19:17:21.410" LastActivityDate="2016-01-24T00:53:53.290" Title="Is it possible to tilt a propeller for attitude control, similarly to jet thrust vectoring?" Tags="&lt;propeller&gt;&lt;attitude&gt;&lt;thrust-vectoring&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24550" PostTypeId="1" CreationDate="2016-01-23T13:57:16.730" Score="8" ViewCount="919" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rpDM6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rpDM6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the MiG-21 use anti surge shutters at high speed? What is the adverse effect on the airflow at such high speeds (despite using a conical spike ahead) which warrants the use of antisurge shutters?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look just ahead of the wing root, below the two red triangles. The anti surge shutter is covered with a red coloured blanking secured with a yellow cord.&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="1961" LastEditDate="2016-01-25T01:42:27.900" LastActivityDate="2016-01-25T02:05:29.673" Title="Why does the MiG 21 use anti surge shutters?" Tags="&lt;inlet&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24551" PostTypeId="2" ParentId="24549" CreationDate="2016-01-23T14:58:25.987" Score="12" Body="&lt;p&gt;Yes, on airships.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Zeppelin_NT&quot; rel=&quot;nofollow noreferrer&quot;&gt;Zeppelin NT&lt;/a&gt; can rotate its two forward and one rear propellers to create lift instead of thrust, a capability of particular value when the airship descends in an atmosphere with a strong temperature gradient. From &lt;a href=&quot;http://zeppelin-nt.de/en/zeppelin-NT/technology.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt; about the Zeppelin NT:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two forward propellors swivel to 120° and the aft one to 90°, and&#xA;  a fixed aft lateral propeller give a high level of manoeuverability,&#xA;  and enable smooth, quiet flight and impressive fuel economy. Some of&#xA;  the unique flight characteristics come from the swivelling propellers,&#xA;  like vertical take offs, precise landings, hovering over exact&#xA;  locations, turns on its axis and flying backwards.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t4FXW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t4FXW.jpg&quot; alt=&quot;Zeppelin-NT-Airship-Tail-Propellers&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail propellers of the Zeppelin NT Airship. While the sideways mounted propeller is fixed, the rear propeller can swivel through 90° (picture &lt;a href=&quot;http://static1.1.sqspcdn.com/static/f/343804/12547391/1307226533123/Zeppelin-NT-Airship-Tail-Propellers.jpg?token=94BpJ2RmVayN4macmvz9w7C0BvQ%3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PnC3j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PnC3j.jpg&quot; alt=&quot;Front view of the Zeppelin NT with the forward propellers tilted up&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Front view of the Zeppelin NT with the forward propellers tilted up (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Farmers-ZeppelinNT.jpg/640px-Farmers-ZeppelinNT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example would be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow noreferrer&quot;&gt;V-22 Osprey&lt;/a&gt;, obviously, but you might prefer to call those whirly things rotors, not propellers. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-23T15:05:23.673" LastActivityDate="2016-01-23T15:05:23.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24552" PostTypeId="2" ParentId="24542" CreationDate="2016-01-23T15:15:24.953" Score="9" Body="&lt;p&gt;First, the precise terms is not fins, but control surfaces. Fins would be fixed but the four rear surfaces can rotate around a spanwise axis. By rotating, they can be positioned at an angle to the airflow, thus deflecting it and creating an opposing force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare that to a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9504/what-is-the-difference-between-the-v-shape-tail-and-the-straight-tail-on-the-bee/9509#9509&quot;&gt;V-tail on an aircraft&lt;/a&gt;. They work in the same way by creating a force normal to their plane. While this force has a vertical and horizontal component, the horizontal components of the single surfaces cancel each other when all surfaces are rotated by the same angle. Their vertical components will add up, creating a pitching moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the left and right surfaces are rotated by the opposite angle, their vertical force component will cancel while the horizontal component will add up, thus creating a yawing moment which swings the tail around.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If it were to pitch downwards, which fins would need to move and in&#xA;  which direction?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;All four surfaces will move trailing edge down, so the resulting force will point up and pitch the whole craft nose down.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-23T15:15:24.953" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24553" PostTypeId="2" ParentId="24530" CreationDate="2016-01-23T15:44:33.327" Score="8" Body="&lt;p&gt;The full list of airliners and business jets is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sud Aviation Caravelle&lt;/li&gt;&#xA;&lt;li&gt;Tupolev Tu-104&lt;/li&gt;&#xA;&lt;li&gt;Tupolev Tu-124&lt;/li&gt;&#xA;&lt;li&gt;Tupolev Tu-144&lt;/li&gt;&#xA;&lt;li&gt;Concorde prototypes&lt;/li&gt;&#xA;&lt;li&gt;Learjet 25&lt;/li&gt;&#xA;&lt;li&gt;Learjet 35&lt;/li&gt;&#xA;&lt;li&gt;Dassault Falcon 20&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/57z9r.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/57z9r.jpg&quot; alt=&quot;Concorde during brake tests&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde during brake tests (picture &lt;a href=&quot;http://thumbs.media.smithsonianmag.com/filer/concorde_d.jpg__600x0_q85_upscale.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even some gliders used them (SHK, HKS, SB-5, Salto)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mok2J.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mok2J.jpg&quot; alt=&quot;Hirth SHK with brake chute&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hirth SHK with brake chute (picture &lt;a href=&quot;http://cdn.c.photoshelter.com/img-get/I0000n7nq8gwb3N8/s/900/900/20100606-0007Hwei.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Brake chutes increase drag and allow a steeper approach, which helps to control the touchdown point with great precision. If the aircraft is too high, just push the stick forward - the drag of the chute prevents the aircraft from accelerating too much and the increased drag at higher speed gets rid of the excess height quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the ground the drag of the chute reduces the rollout distance which is especially helpful for aircraft with a high touchdown speed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-23T16:34:34.080" LastActivityDate="2016-01-23T16:34:34.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24554" PostTypeId="2" ParentId="24548" CreationDate="2016-01-23T15:56:08.050" Score="7" Body="&lt;p&gt;In most cases, FAA approach charts do not provide a requirement for a ceiling as you say, but rather provide the minimum altitude that a pilot may descend to without having the runway environment in sight (the DH/MDA) and the minimum required visibility.&lt;sup&gt;1&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;In fact, as described in the &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjGx_-mq8DKAhVol4MKHUyeAFQQFggcMAA&amp;amp;url=http%3A%2F%2Fwww.faa.gov%2Fregulations_policies%2Fhandbooks_manuals%2Faviation%2Finstrument_procedures_handbook%2Fmedia%2Fchapter_4.pdf&amp;amp;usg=AFQjCNE18eDlmOvGG05yEStAKlC2Sb2BZA&amp;amp;sig2=noy7ytWq_Rrcz8Zc8qMV3A&amp;amp;bvm=bv.112454388,d.amc&quot; rel=&quot;noreferrer&quot;&gt;FAA Instrument Procedures Handbook, Page 4-7&lt;/a&gt; and in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM, section 5-4-20(e)&lt;/a&gt;, air carrier pilots, who are restricted from even beginning an approach if the reported weather is below minimums, are only restricted by the visibility and may fly the approach  when the reported ceiling is lower than the minimum altitude on the approach plate (note that this does not apply to Part 91 operations).&lt;/p&gt;&#xA;&lt;p&gt;The main reason for this is that a ceiling does not necessarily cover 100% of the sky over the airport environment, and it is quite possible to see the runway even when there is a reported ceiling.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;References&lt;/h2&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjGx_-mq8DKAhVol4MKHUyeAFQQFggcMAA&amp;amp;url=http%3A%2F%2Fwww.faa.gov%2Fregulations_policies%2Fhandbooks_manuals%2Faviation%2Finstrument_procedures_handbook%2Fmedia%2Fchapter_4.pdf&amp;amp;usg=AFQjCNE18eDlmOvGG05yEStAKlC2Sb2BZA&amp;amp;sig2=noy7ytWq_Rrcz8Zc8qMV3A&amp;amp;bvm=bv.112454388,d.amc&quot; rel=&quot;noreferrer&quot;&gt;FAA Instrument Procedures Handbook, Page 4-7&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;14 CFR Part 135, section 135.225 states that pilots may not begin an&#xA;instrument approach unless the latest weather report indicates that&#xA;the weather conditions are at or above the authorized IFR landing&#xA;minimums for that procedure. 14 CFR Part 135, section 135.225 provides&#xA;relief from this rule if the aircraft has already passed the final&#xA;approach fix (FAF) when the weather report is received. &lt;strong&gt;It should be&#xA;noted that the controlling factor for determining whether or not the&#xA;aircraft can proceed is reported visibility&lt;/strong&gt;. RVR, if available, is the&#xA;controlling visibility report for determining that the requirements of&#xA;this section are met. The runway visibility value (RVV), reported in&#xA;statute miles (SM), takes precedent over prevailing visibility. There&#xA;is no required timeframe for receiving current weather prior to&#xA;initiating the approach.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIM, section 5-4-20(e)&lt;/a&gt; says:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;e. Published Approach Minimums. Approach minimums are published for&#xA;different aircraft categories and &lt;strong&gt;consist of a minimum altitude (DA,&#xA;DH, MDA) and required visibility&lt;/strong&gt;. These minimums are determined by&#xA;applying the appropriate TERPS criteria. When a fix is incorporated in&#xA;a nonprecision final segment, two sets of minimums may be published:&#xA;one for the pilot that is able to identify the fix, and a second for&#xA;the pilot that cannot. Two sets of minimums may also be published when&#xA;a second altimeter source is used in the procedure. When a&#xA;nonprecision procedure incorporates both a stepdown fix in the final&#xA;segment and a second altimeter source, two sets of minimums are&#xA;published to account for the stepdown fix and a note addresses&#xA;minimums for the second altimeter source.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Notes&lt;/h2&gt;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Under relatively rare conditions, TERPS specifies that a ceiling is required for a specific approach, but this will be notated on the approach chart with the words &lt;strong&gt;CEILING REQUIRED&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-23T19:21:33.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24556" PostTypeId="2" ParentId="24548" CreationDate="2016-01-23T17:24:30.560" Score="3" Body="&lt;p&gt;The other two answers are good ones &amp;amp; correct as far as they go, although I don't think either entirely addresses the question as posted regarding when a pilot has to have both ceiling and vis, or vis only, and the differences between ICAO and FAA criteria.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All approaches will have PUBLISHED both a ceiling and a visibility minimum.  Whether you're required to have both of those in order to begin the approach is a separate question.  (Or, in some cases, you don't have to have either one -- FAR Part 91 for instance.  Under those rules, you can start the approach having neither one.  Maybe you're just flying the approach in order to practice the missed approach, and you're okay with the fact that you almost certainly won't be able to land out of it.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For circling approaches, every authority I'm aware of that requires having minimum weather in order to begin the approach, requires that you must have &lt;strong&gt;both&lt;/strong&gt; ceiling and vis.  For straight-in approaches, some authorities require that you must have both, and other require only the published visibility.  In FAA rules, flying a straight-in &quot;Vis Only&quot; is generally allowed; some operators (such as the Air Force's Air Training Command, now the Air Education and Training Command, at least when I went through pilot training) require that their pilots have both in order to begin the approach.  Major airlines typically have approval to fly straight-in approaches &quot;Vis only.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea is, don't start an approach unless there's a good probability that you can land out of it.  (Part 91, as described above, is less restrictive here.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that ICAO does the same thing, in that under ICAO rules generally, straight-in approaches may be flown &quot;Vis Only&quot; and the ceiling disregarded for exactly the reason that LNafzinger mentions -- the reported ceiling may not be perfectly uniform and you may well be able to see the necessary runway/lights/environment at your Decision Altitude even though you're somewhat above the published ceiling value.  Some nations may choose a more limiting rule that requires both ceiling and vis -- I think at least one nation in the Caribbean does so, although I don't remember which.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Okay, follow-up question: why publish a ceiling if operators are free to ignore it?  Answer: besides those operators who choose to require it, it's also used when considering the requirements for alternates and when an alternate qualifies.  Those rules have conditions like &quot;if the ceiling is lower than XXX above the lowest authorized approach's minimum ceiling and/or the visibility is lower than YYY above the lowest authorized approach's minimum visibility, then...&quot;  Rules like that can only work when the ILS and PAR approaches have the published ceiling values as Jonathan Walters posted.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-01-23T17:24:30.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24559" PostTypeId="2" ParentId="24549" CreationDate="2016-01-23T19:00:00.970" Score="5" Body="&lt;p&gt;While in case most VTOL aircraft, the rotors are tilted, one unique case is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Curtiss-Wright_X-19&quot; rel=&quot;nofollow noreferrer&quot;&gt;Curtis Wright X-19&lt;/a&gt;, which had what the company called tilt-propellers. Curtis Wright at that point was a propeller manufacturer and its designers made the aircraft around the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7j5ym.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7j5ym.jpg&quot; alt=&quot;X-19&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from warbirdinformationexchange.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This in turn, was developed from the X-100&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VxgVy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VxgVy.jpg&quot; alt=&quot;X-100&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airandspace.si.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The designers used a property of the propeller &lt;a href=&quot;http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19690014000&quot; rel=&quot;nofollow noreferrer&quot;&gt;called the radial lift force&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... as a propeller is inclined towards the vertical from the horizontal, the resultant of the propeller's thrust and the pressure of the relative wind acting on the rotating disk is a force with an additional lift component in the vertical axis. ... short propellers with wide blades magnified the radial force effect by increasing the surface area of the propeller disk without the compressibility issues of longer rotor blades. This offered a potential advantage over other tilt-rotor models, such as the Bell XV-3, with longer and narrower blades that did not have sufficient surface area to take advantage of the phenomenon. The added lift generated from the radial force permitted an aircraft built with the specially constructed lifting propellers to have smaller wings, which decreased weight and high-speed drag. This resulted in the most aerodynamically efficient of all of the VTOL designs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In hover, the roll control was provided by differential pitch of the propellers. The aircraft basically behaved like a high-disc loading helicopter and was statically unstable in hover and in pitch and roll at low speed. The aircraft crashed during its first transition flight in 1965, with the progra ending soon.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This method is also used in a number of &lt;a href=&quot;http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/2013/ICRA-2013-Ryll.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;small UAVs&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-23T19:00:00.970" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24560" PostTypeId="2" ParentId="24549" CreationDate="2016-01-23T20:47:18.787" Score="1" Body="&lt;p&gt;Yes, this is possible because many helicopters use this method to some of their control. There are also some aircraft like the V-22 Osprey which use some variation on this control method.&lt;/p&gt;&#xA;" OwnerUserId="13140" LastEditorUserId="12220" LastEditDate="2016-01-24T00:53:53.290" LastActivityDate="2016-01-24T00:53:53.290" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24561" PostTypeId="1" AcceptedAnswerId="24562" CreationDate="2016-01-23T22:59:08.333" Score="7" ViewCount="1022" Body="&lt;p&gt;I was reading &lt;a href=&quot;http://code7700.com/slots.html&quot;&gt;this page&lt;/a&gt; about Eurocontrol and flight plans. The author refers several times to a &quot;local handler&quot; who apparently assists in dealing with ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a handler, who do they work for and what do they do?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="3825" LastEditDate="2016-01-23T23:48:19.327" LastActivityDate="2016-01-23T23:48:19.327" Title="What is an aviation handler?" Tags="&lt;ground-operations&gt;&lt;international&gt;&lt;fbo&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24562" PostTypeId="2" ParentId="24561" CreationDate="2016-01-23T23:12:21.743" Score="8" Body="&lt;p&gt;Handlers are private companies who provide services (for a fee) to pilots and passengers when they fly in and out of an airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the airport, sometimes handlers are required by the local authorities to be used, and other times there are not even any handlers available (a lot of US airports do not have them, for instance).  Often though, they are optional and there to assist crews that are unfamiliar with the procedures at a new airport or who want their assistance as a convenience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They typically assist with coordinating things like fuel, lavatory service, flight plans, local permits, passenger transportation, catering, coffee/ice/newspapers, etc.  Many times they pay for everything (in the local currency) and provide one consolidated bill for the client to pay.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that handlers can be employed by local FBO's (Fixed Based Operators), or they can be part of a larger international company that provides handling services all over the world.  In either case, they are generally coordinating all of the different parties and services needed in order to operate an aircraft in and out of their airport.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-01-23T23:24:00.923" LastActivityDate="2016-01-23T23:24:00.923" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24563" PostTypeId="1" AcceptedAnswerId="24564" CreationDate="2016-01-24T00:45:10.577" Score="12" ViewCount="1712" Body="&lt;p&gt;I was reading about plane de-icing the other day, and someone posted a comment saying that was their job, and when no planes needed de-icing they just slept/waited in the de-icing truck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was looking just now at de-icing jobs, and found one at heathrow that said it was a permanent 40-hour/week job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what do they actually do during summer? Do they do a different job or do they just wait in case a random (unlikely) snow storm passes by?&lt;/p&gt;&#xA;" OwnerUserId="2907" LastActivityDate="2016-09-02T17:17:41.463" Title="What do de-icers do during summer?" Tags="&lt;ground-operations&gt;&lt;career&gt;&lt;deice&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24564" PostTypeId="2" ParentId="24563" CreationDate="2016-01-24T00:51:36.283" Score="7" Body="&lt;p&gt;Most de-icers are run by the airport FBO so the people who work on de-icing in the winter work on other FBO duties such as refueling and the like when there is no de-icing to do. Some de-icers are just hired permanently for winter times.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-24T00:51:36.283" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24565" PostTypeId="1" AcceptedAnswerId="24568" CreationDate="2016-01-24T02:59:45.157" Score="10" ViewCount="612" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Glory_%28optical_phenomenon%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;glory&lt;/a&gt; being this optical phenomenon:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n3qcS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n3qcS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://pix-hd.com/picture+of+rainbow+from+airplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;del&gt;It reveals the presence of &lt;a href=&quot;https://en.wikipedia.org/wiki/Supercooling&quot; rel=&quot;nofollow noreferrer&quot;&gt;supercooled water&lt;/a&gt;, a hazard for an aircraft&lt;/del&gt; (see answers).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Due to the way it can materialize, the center of the rings indicates the position of the observer in the airliner. So this one was not shot from the cockpit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Does it represent a specific icing hazard?&#xA;How frequent is it?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="12720" LastEditDate="2016-01-24T22:01:21.503" LastActivityDate="2016-01-24T22:01:21.503" Title="Is the &quot;glory&quot; optical phenomenon frequently seen by aircraft pilots?" Tags="&lt;icing&gt;&lt;cold-weather&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24566" PostTypeId="1" CreationDate="2016-01-24T03:08:37.350" Score="8" ViewCount="328" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/24365/how-should-isopropyl-alcohol-be-used-as-an-avgas-fuel-system-icing-inhibitor&quot;&gt;This question&lt;/a&gt; established a basis for the use of 100% Isopropyl Alcohol (IPA) as a Fuel System Icing Inhibitor (FSII) in aviation gasoline systems. However, &lt;a href=&quot;http://www.ttt-aviation.com/Cessna-letter.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Cessna Service Letter&lt;/a&gt; documents that IPA is not to be used as a FSII with automotive gasoline in Lycoming powered Cessna aircraft, or indeed in any Lycoming aircraft whatsoever, in accordance with Lycoming Service Instruction No. 1070R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, &lt;a href=&quot;http://www.autofuelstc.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Peterson&lt;/a&gt; offers their &lt;a href=&quot;http://www.autofuelstc.com/stc_specs.phtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;auto fuel STC&lt;/a&gt; for many aircraft, including Lycoming powered Cessnas, allowing the use of certain types of non-ethenol automotive fuels. Peterson is known for being outspoken about the &lt;a href=&quot;http://www.autofuelstc.com/fuel_testing.phtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;problems&lt;/a&gt; with ethanol as an additive in automotive gasoline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is twofold:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;firstly, is there any documented basis for the use of IPA as an FSII with any type of automotive gasoline in certified aircraft fuel systems (I am thinking part 23 certified aircraft, to exclude non-certified aircraft); and,&lt;/li&gt;&#xA;&lt;li&gt;secondly, is there any documentation for the allowance or prohibition of the use of IPA as an FSII with a Peterson auto fuel STC?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2018-08-06T20:40:16.063" Title="Can IPA be used as a FSII with MoGas, particularly with a Peterson STC?" Tags="&lt;fuel&gt;&lt;anti-ice&gt;&lt;icing&gt;&lt;fuel-systems&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24567" PostTypeId="2" ParentId="24565" CreationDate="2016-01-24T03:23:11.120" Score="-2" Body="&lt;p&gt;Yes. It represents a potential icing hazard. As you noted, the glory (or pilot's halo or glory of the pilot) indicates the presence of liquid water in the cloud. If the temperature is in the freezing range and the aircraft descends into the cloud where glory is seen, icing can be expected.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.navcanada.ca/EN/media/Publications/Local%20Area%20Weather%20Manuals/LAWM-Prairies-2-EN.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NavCanada manual&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The glory is one of the most common forms of halo visible in the sky. For the pilot it is a warning sign of potential icing because it is only visible when there are liquid water droplets in the cloud. If the air temperature at cloud level is below freezing, icing will occur in those clouds that produce a glory.&lt;/p&gt;&#xA;&lt;p&gt;A glory can be seen by looking downwards and seeing it surround the shadow that your aircraft casts onto the cloud tops. They can also be seen by looking upwards towards the sun (or bright moon) through clouds made of liquid droplets. ... . Although ice crystals often produce other halos&#xA;and arcs, only water droplets form bullseyes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Glory is quite common. In pre-airplane days, glories were quite rare and one good way to see them was to go up a mountain, a phenomenon called Brocken Spectre. However, with the advent of air travel, the phenomenon has become more common.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-24T03:32:53.827" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24568" PostTypeId="2" ParentId="24565" CreationDate="2016-01-24T03:26:55.900" Score="11" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Yes, pilots frequently see this phenomenon.&lt;br&gt;&#xA;No, it does not necessarily present a specific icing hazard.&lt;br&gt;&#xA;Yes, in some circumstances it &lt;em&gt;can&lt;/em&gt; be in indication of an icing hazard.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longer Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Speaking for myself, yes, I often see this. I cannot speak for all pilots, but I think many pilots do also see this. The phenomenon depends on several conditions, the primary ones being angle of the aircraft relative to the sun, and the presence of liquid water droplets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I would contest the assertion that it reveals the presence of supercooled water. I see the phenomenon most often in low level fog banks or mist. I do a lot of early morning flying when the conditions are right for the phenomenon. On many of these occasions the air temperature is well above freezing, and all other weather conditions would also indicate that the water droplets are &lt;em&gt;not&lt;/em&gt; supercooled. See the following photos from &lt;a href=&quot;https://en.wikipedia.org/wiki/Glory_%28optical_phenomenon%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;the wikipedia page&lt;/a&gt; showing the phenomenon in low level (probably above 0°C) fog banks:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xl6Mz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xl6Mz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZSiMH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZSiMH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the water droplets connected with the phenomenon are not necessarily supercooled, the risk of icing will depend on other factors, primarily outside air temperature. Though the &quot;glory&quot; phenomenon does indicate visible liquid water droplets, it does not necessarily indicate an icing risk. A thorough pre-flight risk assessment for icing conditions should answer that question on a case by case basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the conditions in which many airline passengers might see the phenomenon may well be at an altitude high enough that the liquid water droplets may very well be supercooled. In such cases the &quot;glory&quot; phenomenon indicates that the cloud in question is not formed of ice crystals (which pose little icing risk) but of liquid, and possibly supercooled liquid droplets. &lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-24T14:37:41.237" LastActivityDate="2016-01-24T14:37:41.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24569" PostTypeId="1" AcceptedAnswerId="24574" CreationDate="2016-01-24T04:22:05.347" Score="12" ViewCount="6945" Body="&lt;p&gt;Which are the aircraft models that need their tail to be supported by a jack when empty? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia says this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Aircraft Tripod Jack&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;They are used to support a parked aircraft to prevent their tail from&#xA;  drooping or even falling to the ground. When the passengers in the&#xA;  front get off an aircraft, the aircraft becomes tail heavy and the&#xA;  tail will droop..... When needed, they are tugged to the tail and&#xA;  setup by manpower. Once setup, no supervision to the jack is needed&#xA;  until the aircraft is ready to leave.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Are there even commercial airliners that need to be supported this way every time they load / unload? Sounded like a lot of work for ground staff. Was this a legacy equipment thing or still in use today?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_support_equipment&quot;&gt;https://en.wikipedia.org/wiki/Ground_support_equipment&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2019-04-24T21:57:53.893" Title="Which Aircraft Models need a Tripod Jack for tail support at airport?" Tags="&lt;commercial-aviation&gt;&lt;ground-operations&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24570" PostTypeId="2" ParentId="24569" CreationDate="2016-01-24T05:51:10.770" Score="9" Body="&lt;p&gt;DC-8 freighters used tail supports as a safety precaution. As I remember, if you loaded them properly the support wasn't needed, but people didn't always do that. The cargo door was forward of the wing. I've long since thrown out my DC-8 weight &amp;amp; balance manuals, but as best I remember, the proper protocol was to put the desired most forward ULDs in first and slide them to their positions forward of the door. Next you would put in the rearmost ULD, but then move it just far enough aft to get the next ULD on, then move it and the previous one just enough aft to get the next one on, and so on. At some point you had enough weight forward of the main gear to start moving pallets all the way to the rear. If you miscalculated, the airplane would sit on the installed tail support. This reportedly happened at Newark, as I remember, in the early 1990s, but they had neglected to put up the tail support. The airplane sat on it's tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same attention to balance was also needed when unloading. Read &lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/US/1994-11-30-US.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this link&lt;/a&gt; for an unloading accident when the tail stand collapsed, causing one of the cargo pallets to roll down to the tail of the cargo compartment.  Three loaders were able to get out of the way of the runaway pallet, but the fourth got his foot caught, sustaining serious injury.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="22726" LastEditDate="2018-05-25T00:25:07.013" LastActivityDate="2018-05-25T00:25:07.013" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="24571" PostTypeId="1" CreationDate="2016-01-24T06:00:47.867" Score="9" ViewCount="2142" Body="&lt;p&gt;How do pilots end up flying a specific plane type? Do they choose what type of plane they want to fly and persevere the goal or do you generally get an ATPL and then get a rating based on what your employers aircraft models are?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I love turboprops and in particular the ATR42, I get employed, if I'm lucky or good, by an airline that has ATR42/72 mixed with other aircraft in the fleet. Do I have a choice as a pilot or do I have to strictly adhere to the aircraft that my employer assigns me?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="770" LastEditDate="2016-01-24T14:42:54.643" LastActivityDate="2016-01-24T14:44:52.780" Title="Do pilots choose which aircraft to get rated for or is it the employer that decides it?" Tags="&lt;pilots&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24572" PostTypeId="2" ParentId="24571" CreationDate="2016-01-24T06:15:22.003" Score="10" Body="&lt;p&gt;It depends. In the US and at airlines, seniority rules what aircraft, and what base you start at. Usually, there will be bases for pilots, that are then broken down by aircraft(though not all bases will have options for all aircraft types) and then Captain and FO spots for each group. For example at Delta, at one point, the new hires were going primarily 767 FO spots, at JFK. As their seniority in the airline increases, they can then try to bid to a different aircraft or a captain spot on any aircraft that their seniority can hold, or to a different base. Some may spend a bulk of their career as FOs and just like being a senior FO at a base or type, others will jump around slowly moving up and progressing through various options, depending on the individual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, and airlines, generally you don't pay for your training for the type ratings. Though, Southwest has in the past required applicants to have a 737, and a few others require the type rating already in hand. &lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="770" LastEditDate="2016-01-24T14:44:52.780" LastActivityDate="2016-01-24T14:44:52.780" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24573" PostTypeId="1" CreationDate="2016-01-24T06:17:04.130" Score="27" ViewCount="6070" Body="&lt;p&gt;I understand this may be a dumb question to ask, but - in the opening sequence of &lt;em&gt;Golden Eye&lt;/em&gt; - James Bond chases after a plane that has rolled off the side of a cliff in his motorcycle, and then somehow (movie magic) climbs into it and pilots it away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not asking about the physics of the motorcycle stunt - except keeping it to the aircraft part:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this something that can happen in real life - that is, an elevated airfield so short, that the plane has to &quot;fall&quot; to obtain enough speed to gain lift?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has something like this ever been attempted, even if simply as an exercise in flight dynamics?&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="3504" LastEditDate="2016-01-26T15:32:05.007" LastActivityDate="2016-01-26T15:32:05.007" Title="Is it possible to take off on an elevated short field by &quot;falling&quot;?" Tags="&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="11" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24574" PostTypeId="2" ParentId="24569" CreationDate="2016-01-24T06:19:50.920" Score="16" Body="&lt;p&gt;Tripods are mostly found in cargo aircraft (and combis) as the cg shift is severe there (particularly for front loading). A good example is the Boeing 747s. Also used in DC10/MD11s used as freighters. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cSHaw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cSHaw.jpg&quot; alt=&quot;747F&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://www.reddit.com/r/aviation/comments/1hz3b3/md11_unloading_accident/&quot; rel=&quot;nofollow noreferrer&quot;&gt;reddit.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some 747-400 combis also use these, though it is mainly for cargo loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fDpq7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fDpq7.jpg&quot; alt=&quot;747-400M&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Photo: Je89 W. / Source: PlanePictures.Net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some passenger airliners are prone to tipping (&lt;a href=&quot;http://www.briansumers.com/home/2015/7/27/united-airlines-has-had-some-tail-tip-problems-with-the-boeing-737-900&quot; rel=&quot;nofollow noreferrer&quot;&gt;737-900 comes to mind&lt;/a&gt;) and are usually supported by a pole rather than by a tail stand (same procedure is used in a KC-135 tanker too). For example, a Boeing 737-932ER with tail support.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/es8uF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/es8uF.jpg&quot; alt=&quot;B737-900&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/6559212/1/&quot; rel=&quot;nofollow noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tail supports are not strictly necessary and the loading can be carried out sequentially (from front to back) for safe operation, but are used as a  precaution. In some aircraft (like ATR-72 and Saab 340, called pogo sticks) small tubings are attached to the rear fuselage to prevent tipping over when loading/unloading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kuB7n.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kuB7n.jpg&quot; alt=&quot;ATR 72&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from theflyingengineer.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nose can be tethered to prevent tipping during loading/unloading as done in this Korean Air 747F&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2MtZG.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2MtZG.gif&quot; alt=&quot;747F&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://cargo.koreanair.com/ecus/fpg/servlet/CargoDicServlet?version=eng&amp;amp;pid=21&amp;amp;e_seq=26&quot; rel=&quot;nofollow noreferrer&quot;&gt;koreanair.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-04-24T21:57:53.893" LastActivityDate="2019-04-24T21:57:53.893" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24576" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T08:17:11.510" Score="30" Body="&lt;p&gt;Is it &lt;em&gt;theoretically possible&lt;/em&gt;? Sure.&lt;br&gt;&#xA;Is it &lt;em&gt;realistic&lt;/em&gt; or &lt;em&gt;probable&lt;/em&gt;? Absolutely not.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If there is not enough space for the airplane to accelerate to takeoff speed it will be effectively stalled when it reaches the end of the ground. That means that as soon as it runs out of ground it effectively becomes a ballistic projectile: it keeps moving forward, but it also starts to fall because of gravity. &lt;a href=&quot;https://youtu.be/F2gdFK-2mY4?t=1m12s&quot;&gt;You can see this in the Goldeneye clip&lt;/a&gt; - the plane adopts a nose-down attitude shortly after it leaves the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually, given enough time, the airplane will reach a flyable airspeed (between gravity accelerating it down and its thrust propelling it forward). How far it needs to fall before that happens depends on a number of factors, but if the ground is sloping downward at an angle such that the aircraft's ballistic trajectory does not intersect the ground before it can reach flying speed you &lt;em&gt;could&lt;/em&gt; theoretically make such a takeoff.&lt;br&gt;&#xA;The obvious downside is that if things don't go perfectly in the attempt you will intersect the ground in uncontrolled flight (&quot;crash&quot;).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In the Goldeneye scenario the aircraft is already in a fairly extreme dive when Bond manages to get aboard, so for our intrepid secret agent it's not so much a matter of getting the aircraft to a flying speed (it's probably there already) but rather of recovering from the dive before hitting the ground &lt;em&gt;and&lt;/em&gt; without over-stressing the airframe and causing parts to break off.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-01-24T08:17:11.510" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24577" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T08:38:31.400" Score="12" Body="&lt;p&gt;It sure is possible, and sure has happened! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check out &lt;a href=&quot;https://www.youtube.com/watch?v=F_8NMODxSlM&quot;&gt;this video&lt;/a&gt;. Looks like a whole lot of fun. As long as there is enough forward trajectory to clear the edge, and enough room before the ground, it can be done. I wouldn't like your chances of pulling it off in a larger aircraft however, and the piloting technique would need to be precise. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="3746" LastEditDate="2016-01-24T09:11:40.743" LastActivityDate="2016-01-24T09:11:40.743" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24578" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T09:55:29.927" Score="18" Body="&lt;p&gt;I'm taking that you mean taking off (for the want of a better word) when the runway is unavailable- trade altitude for gaining speed and get back to controlled flight. This is certainly &lt;em&gt;possible&lt;/em&gt; but not recommended as it puts too much premium on pilot skill and luck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;http://www.wildwestaircraft.com/deadstick-video/&quot;&gt;videos in the internet&lt;/a&gt; which shows exactly this being done, but whether anyone would want to try this is questionable. Atleast this shows that as long as the aircraft is kept clear of the ground below for a reasonable amount of time and the aircraft does not stall, the aircraft could be flown off the cliff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way of looking at this is to consider the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airborne_aircraft_carrier&quot;&gt;experiments carried out in 1930s&lt;/a&gt; with airships and &lt;a href=&quot;https://en.wikipedia.org/wiki/FICON_project&quot;&gt;1950s with large bombers&lt;/a&gt;, which launced aircraft from an altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_XF-85_Goblin&quot;&gt;McDonnel Douglass XF 85 Goblin&lt;/a&gt; was purpose built to be carried and launched from bombers; the launches were successful, the trouble was with the retrieval of the aircraft. The advent of the air-to-air refueling put and end to the experiments. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-24T09:55:29.927" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24579" PostTypeId="1" CreationDate="2016-01-24T13:35:41.633" Score="12" ViewCount="823" Body="&lt;p&gt;What is the relative contribution to braking forces in a typical large commercial aircraft  from the three different devices contributing to braking after touchdown:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Wheel brakes&lt;/li&gt;&#xA;&lt;li&gt;Speed brakes / Spoilers&lt;/li&gt;&#xA;&lt;li&gt;Reverse Thrusters&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The relative contribution should change with velocity so even nicer if we have the velocity depended thrust contributions. e.g. Reverse Thrusters provide more braking at the initial high velocity part of the roll out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm posting a illustrative (but totally made-up) graph to clarify for what I was looking for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9lYJw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9lYJw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for either empirical data or theoretical predictions for the thrust. Qualitatively I'd expect the spoiler contribution to fall off with a square law dependence on velocity. I'd think the reverse thrust offers a somewhat constant component but perhaps higher initially due to parasitic drag by the clamshells? Not sure, and this is what I'm trying to get: A quantitative relationship. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case the answer will vary hugely depending on aircraft, I'm open to any specific case being illustrated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's use the limiting case of full brakes with anti skid on. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PS.&lt;/strong&gt; Since spoilers directly add to drag as well as indirectly help braking by dumping lift teasing out their braking thrust contribution might be harder?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-07-14T07:22:52.467" LastActivityDate="2016-07-14T07:22:52.467" Title="What are the relative braking contributions from wheel brakes, spoilers and thrust reversers?" Tags="&lt;theory&gt;&lt;braking&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24580" PostTypeId="1" CreationDate="2016-01-24T13:47:15.430" Score="10" ViewCount="75464" Body="&lt;p&gt;As I asked &lt;a href=&quot;https://aviation.stackexchange.com/questions/24548/is-there-any-difference-on-landing-minima-between-icao-and-faa&quot;&gt;question about weather minimums&lt;/a&gt; yesterday, I've read some material including TERPs. And In the FAA 8260.3b, 'Taking and Landing Minimims' 3.1 there is one sentence &quot;alternate minimims, when specified, must be stated as ceiling and visibility.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I don't know What alternate minimums exactly means because I am not native English speaker. I have used English dictionary to find exact meaning but failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between approach minimums and alternate minimums?&lt;/p&gt;&#xA;" OwnerUserId="12972" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2020-02-20T02:22:18.843" Title="What are &quot;Alternate Minimums&quot;?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;&lt;instrument-procedures&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24581" PostTypeId="2" ParentId="24580" CreationDate="2016-01-24T14:11:23.827" Score="11" Body="&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.169&quot;&gt;FAR 91.169&lt;/a&gt; states that IFR flight plans must include an &lt;em&gt;alternate airport&lt;/em&gt; unless the weather is at least 2000 ft ceiling and 3 miles visibility, from one hour before to one hour afterwards (&lt;em&gt;1-2-3 rule&lt;/em&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same regulation also states that the alternate airport must meet the following critera:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) IFR alternate airport weather minima. Unless otherwise authorized&#xA;  by the Administrator, no person may include an alternate airport in an&#xA;  IFR flight plan unless appropriate weather reports or weather&#xA;  forecasts, or a combination of them, indicate that, at the estimated&#xA;  time of arrival at the alternate airport, the ceiling and visibility&#xA;  at that airport will be at or above the following weather minima:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) If an instrument approach procedure has been published in part 97&#xA;    of this chapter, or a special instrument approach procedure has been&#xA;    issued by the Administrator to the operator, for that airport, the&#xA;    following minima:  &lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(i) For aircraft other than helicopters: The&#xA;      alternate airport minima specified in that procedure, or if none are&#xA;      specified the following standard approach minima:  &lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;(A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles. &lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;(B) For a non-precision approach procedure. Ceiling 800 feet and visibility 2 statute miles.&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-24T14:36:12.713" LastActivityDate="2016-01-24T14:36:12.713" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24582" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T14:20:51.543" Score="8" Body="&lt;p&gt;One of the greatest books on aviation ever written, &lt;em&gt;Fate is the Hunter&lt;/em&gt; by Ernest K. Gann, has a story about departing Africa fully loaded with fuel off of a river in a seaplane, and they couldn't get airbore before the river turned into a waterfall. When they reached the waterfall, they lowered the nose until they reached flying airspeed, and flew away. It wasn't planned, but they made it anyway.  So, yes, it is possible. And run, don't walk, to your favorite bookstore and buy this book. I read it every year.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-24T14:20:51.543" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24583" PostTypeId="2" ParentId="24571" CreationDate="2016-01-24T14:33:30.307" Score="1" Body="&lt;p&gt;Commercially you can choose most of the time within some reason of what aircraft type you would like to fly, however if you join the RAF for example you won't get an option what to fly, when you join as a pilot you get selected by them for whatever aircraft you will be flying, this can range from small light aircraft, to large transportation jets and even helicopters!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope this helps :P&lt;/p&gt;&#xA;" OwnerUserId="13146" LastActivityDate="2016-01-24T14:33:30.307" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24584" PostTypeId="1" CreationDate="2016-01-24T16:00:09.793" Score="5" ViewCount="2491" Body="&lt;p&gt;Is there any rule followed or imposed by commercial airlines that the pilots of a particular plane may not be a married couple? My thinking comes from common workplace rules, where generally HR does not allow a couple to work in the same department, for obvious hierarchical issues.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="62" LastEditDate="2016-01-24T16:32:57.187" LastActivityDate="2016-01-24T23:42:10.443" Title="Is there any rule in commercial aviation, that two pilots in a plane cannot be a married couple?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24585" PostTypeId="1" CreationDate="2016-01-24T17:48:38.877" Score="7" ViewCount="3085" Body="&lt;p&gt;There's an old saying that there's never too much fuel left in your tanks or too much altitude below you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, in terms of airline fuel planning, could there be a situation where an airliner would land with more fuel than is needed for its next flight, to the point that this extra fuel would be problematic?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would this, or other circumstances, necessitate that fuel be &lt;em&gt;removed&lt;/em&gt; from an airliner before a flight, for example due to a higher payload on the upcoming flight?&lt;/p&gt;&#xA;" OwnerUserId="13147" LastEditorUserId="7532" LastEditDate="2016-01-24T23:33:37.860" LastActivityDate="2016-01-24T23:33:37.860" Title="What would happen if an airliner had too much fuel for its next flight?" Tags="&lt;airline-operations&gt;&lt;flight-planning&gt;&lt;fuel&gt;&lt;payload&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24586" PostTypeId="1" AcceptedAnswerId="24596" CreationDate="2016-01-24T17:52:24.997" Score="8" ViewCount="1575" Body="&lt;p&gt;A headwind of 20 knots and a true airspeed for the take-off safety &#xA;speed being 120 knots, the ground speed is only 100 knots.  Getting to a true ground speed of &#xA;only 100 knots will require less distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone can explain to me is that mean that the distance for take off will be less and also the take off speed will be less?&#xA;�&lt;/p&gt;&#xA;" OwnerUserId="12552" LastEditorUserId="19" LastEditDate="2016-06-27T08:01:44.243" LastActivityDate="2017-10-18T13:08:41.277" Title="Why is the take off speed and distance reduced by head winds?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;aerodynamics&gt;&lt;general-aviation&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24587" PostTypeId="2" ParentId="24585" CreationDate="2016-01-24T18:14:20.803" Score="-3" Body="&lt;p&gt;The people refueling the plane just subtract the amount of fuel in the plane from what the plane needs for the next trip from what I understand your question is. The other thing is that because the saying is true, airplanes come in with just enough fuel and not really enough to go anywhere else.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-01-24T18:30:34.810" LastActivityDate="2016-01-24T18:30:34.810" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24588" PostTypeId="2" ParentId="24586" CreationDate="2016-01-24T18:18:17.127" Score="1" Body="&lt;p&gt;Yes, the distance will be less in both cases because the amount of time needed to reach the take-off speed is reduced because the necessary groundspeed is reduced (minus the time needed for 20 more knots in your case). The landing is also reduced for the same reason - less time is needed to come to a complete stop because the groundspeed is lower than the airspeed (also minus the time needed to shave off those 20 knots). This is the main reason why runways are built in the prevailing wind directions and aircraft carriers steam into the wind when conducting flight operations.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="11215" LastEditDate="2017-10-18T13:08:41.277" LastActivityDate="2017-10-18T13:08:41.277" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24589" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T18:56:53.690" Score="5" Body="&lt;p&gt;voretaq7's answer seems to explain quite well what's going on but I suggest taking a look at the 'bungee launching' of gliders/sailplanes. Effectively the aircraft is initially accelerated by an elastic band, and then gains airspeed by falling down from a hill, almost exactly as you ask. &#xA;It is still is used at 2 places in the UK occasionally. The hill must be 'right' for it to work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, this does actually happen in real life, but not with 'normal' (powered) aircraft. &lt;/p&gt;&#xA;" OwnerUserId="11884" LastEditorUserId="11884" LastEditDate="2016-01-24T21:54:38.273" LastActivityDate="2016-01-24T21:54:38.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24590" PostTypeId="2" ParentId="24550" CreationDate="2016-01-24T19:32:17.130" Score="3" Body="&lt;p&gt;From:&lt;a href=&quot;http://www.avialogs.com/en/aircraft/ussr/mikoyangurevitch/mig-21/mig-21bis-pilot-s-flight-operating-instructions.html#download&quot; rel=&quot;nofollow&quot;&gt;Mikoyan-Gurevich MiG-21 Pilot's Flight Operating Instructions&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to operate at supersonic speeds, the engine inlet has a&#xA;movable nose cone that extends as the aircraft speeds up. This keeps&#xA;the shock wave in front of the inlet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine of the MIG-21 is &lt;strong&gt;protected against compressor surges&lt;/strong&gt;(a reversal of air pressures causes air to move in a wrong direction)by the anti-surge shutters that open to restore normal airflow in the engine. Exhaust is routed through a controllable nozzle that opens or closes to maximize engine thrust and smoothness.&lt;/p&gt;&#xA;" OwnerUserId="3010" LastActivityDate="2016-01-24T19:32:17.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24591" PostTypeId="2" ParentId="24585" CreationDate="2016-01-24T19:57:09.700" Score="10" Body="&lt;p&gt;This would be an uncommon situation and the decision on what to do will typically be handled by your dispatcher.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Take the extra gas and restrict passenger/cargo weight as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the easy option but it could mean leaving people behind.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Defuel to the normal amount of fuel needed (e.g. release + taxi + contingency fuel) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This normally means the fuel is considered contaminated and will be disposed of.  There are ways of de-fuelling and re-using that fuel for another plane, but it requires specific operations and equipment that only likely to be available in the hub or perhaps a maintenance station.  De-fuelling can be slow and will delay the flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the end this comes down to either weight restricting the plane or taking a delay and wasting some fuel.  The timing and economics of the decision will depend on many factors and each case would be judged individually.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-24T19:57:09.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24592" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T20:28:15.410" Score="2" Body="&lt;p&gt;The book &lt;a href=&quot;https://books.google.com.au/books?id=f_WvBmqh0RoC&amp;amp;pg=PT187&amp;amp;lpg=PT187&amp;amp;dq=mussolini%20stork&amp;amp;source=bl&amp;amp;ots=KvaMKrD__j&amp;amp;sig=r6677iDACEzfJtlCDY6iluOJWZk&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwiavqfGo8PKAhWG26YKHSEEBzcQ6AEIMTAF#v=onepage&amp;amp;q=mussolini%20stork&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;Hitler's Raid to Save Mussolini by Greg Annussek&lt;/a&gt; (page 6, second to last paragraph) discusses the rescue of Mussolini; they used a 200 meter runup then off a cliff in a Storch.&lt;/p&gt;&#xA;" OwnerUserId="13149" LastEditorUserId="753" LastEditDate="2016-01-24T21:43:41.513" LastActivityDate="2016-01-24T21:43:41.513" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24593" PostTypeId="2" ParentId="24573" CreationDate="2016-01-24T21:55:00.143" Score="16" Body="&lt;p&gt;Yes, an airplane can be launched by gravity acceleration, whether by a short takeoff run, or actual free fall. As other answers have indicated, there are many instances of this taking place from short runways or hillsides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An obscure application of this ability is found in the curious history of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Curtiss_F9C_Sparrowhawk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Curtiss Sparrowhawk&lt;/a&gt;, a &quot;parasite fighter&quot; that launched from US Navy airships. The aircraft was stored in the airship, which was a sort of flying aircraft carrier. To launch, the Sparrowhawk was lowered below the airship by the hook above the wings, the engine was powered up, and the aircraft was released to fall away and gain airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eyfqE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eyfqE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;[&lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:F9C-2_Sparrowhawk_fighter.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;, public domain&lt;/em&gt;]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Video the USS Akron showing Sparrowhawk launch (launch sequence starts at &lt;a href=&quot;https://youtu.be/DTGBFY82Gik?t=100&quot; rel=&quot;nofollow noreferrer&quot;&gt;1:40&lt;/a&gt;)&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/DTGBFY82Gik?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the Sparrowhawk used the launch mechanism for retrieval into the airship. Read more about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Curtiss_F9C_Sparrowhawk&quot; rel=&quot;nofollow noreferrer&quot;&gt;Curtiss F9C Sparrowhawk&lt;/a&gt;, and the two airships that carried it, the &lt;a href=&quot;https://en.wikipedia.org/wiki/USS_Akron_(ZRS-4)&quot; rel=&quot;nofollow noreferrer&quot;&gt;USS Akron&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/USS_Macon_(ZRS-5)&quot; rel=&quot;nofollow noreferrer&quot;&gt;USS Macon&lt;/a&gt; on their Wikipedia pages.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-01-24T21:55:00.143" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24594" PostTypeId="1" AcceptedAnswerId="24597" CreationDate="2016-01-24T22:35:32.977" Score="3" ViewCount="252" Body="&lt;p&gt;Is there a standard policy / guideline that dictates how many minutes a jetway or air bridge must be detached from a commercial aircraft before take-off?&lt;/p&gt;&#xA;" OwnerUserId="13155" LastActivityDate="2016-01-24T23:23:04.217" Title="How many minutes between jetway (air bridge) detachment and take-off?" Tags="&lt;commercial-aviation&gt;&lt;airport&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24595" PostTypeId="2" ParentId="24586" CreationDate="2016-01-24T23:13:21.807" Score="5" Body="&lt;p&gt;The takeoff indicated airspeed - shown on the ASI in the cockpit - will remain the same regardless of the wind. The groundspeed required to takeoff however, is greatly affected by the wind and ambient conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a very simplistic level, it helps to think of indicated airspeed as the speed of the air over the wings. Therefore, if an aircraft is sitting still facing a 20kt wind, the speed of air over the wings - the indicated airspeed - is 20kt, yet the groundspeed (speed across the ground) is 0. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the aircraft needs to rotate at 120kt indicated airspeed, with a 20kt headwind the aircraft only needs to accelerate to 100kt of groundspeed, and thus requiring less takeoff distance. But the ASI will still show 120kt at rotation speed. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-01-24T23:13:21.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24596" PostTypeId="2" ParentId="24586" CreationDate="2016-01-24T23:15:39.710" Score="7" Body="&lt;p&gt;You're correct that a headwind will reduce the takeoff roll (takeoff distance). As far as takeoff speed, the airspeed will remain same, but the ground speed will be reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the simplest sense, an aircraft rotates for takeoff when it generates enough lift (leaving aside other considerations). This is dependent on the &lt;em&gt;airspeed&lt;/em&gt; as the lift generated is propotional to the square of airspeed (provided the other factors like wing area and lift coeffecient are kept constant) at a density altitude. As a result, it is the airspeed, not the groundspeed that matters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have some headwind, the effective groundspeed is reduced by the same amount- resulting in reduced takeoff distance. The effect of the wind on landing distance is similar to the takeoff distance. You can see this in the following figure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J5mas.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J5mas.jpg&quot; alt=&quot;Wind effect&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://avstop.com/ac/flighttrainghandbook/takeoffperformance.html&quot; rel=&quot;noreferrer&quot;&gt;avstop.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it can be seen, the presence of winds can have a significant effect on the takeoff disantances required (note that the airspeed remains the same in all cases). Due to this, the direction of prevailing winds can have a significant effect on determining the runway headings. From &lt;a href=&quot;http://virtualskies.arc.nasa.gov/airport_design/6.html&quot; rel=&quot;noreferrer&quot;&gt;Influences on Airport Layout&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The weather patterns of an area, especially the prevailing winds, are a major factor in determining runway headings. Prevailing winds are defined as the direction from which the winds blow most frequently. Remember that airplanes take off and land into the wind. Let's say that at a given airport the prevailing winds blow in from the west 65% of the year, while 30% of the year the wind blows in from the east, and the remaining 5% coming from the northwest. It would be best then to orient the runway W (27) and E (9). That would mean that approximately 95% of the year airplanes would be landing and taking off into the wind.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-24T23:15:39.710" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24597" PostTypeId="2" ParentId="24594" CreationDate="2016-01-24T23:23:04.217" Score="9" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;while I don't think such a regulatory minimum would make sense, I'm still curious about whether it exists.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, there is no such regulatory minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On average, it's between 10 and 20 minutes from pushback to takeoff, although there are a couple of places I can think of (very short taxi from gate to runway) that I've seen it done in under five minutes.  That's moving pretty fast, though -- almost nonstop checklists, other than during the time the engines are starting.  But whatever you can do safely, is fine as far as regulations are concerned.  If you're ready to go, no regulation makes you wait.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the aircraft, there may be an engine warmup requirement or recommendation.  That's typically much more restrictive for the first flight of the day, and that would be a limiting factor in the very short taxi cases.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-01-24T23:23:04.217" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24599" PostTypeId="2" ParentId="24584" CreationDate="2016-01-24T23:42:10.443" Score="6" Body="&lt;p&gt;The Air Force, at least when I was flying there, had strict rules forbidding a husband and wife flying as crewmembers in the same aircraft.  Generally, airlines in the US don't have to have any similar policy, and there are plenty of examples of married couples (either pilot-pilot, pilot-flight attendant, or flight attendant-flight attendant) working a flight together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An individual airline might be able to create such a policy themselves (although I have no idea if there would be legal grounds for a married couple to challenge the rule), but at least in the US there's no legal requirement that prohibits it.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-01-24T23:42:10.443" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24600" PostTypeId="2" ParentId="24550" CreationDate="2016-01-25T02:05:29.673" Score="5" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/9432/pratt-whitney-jt3d-inlet-doors-purpose&quot;&gt;Normally&lt;/a&gt;, such shutters are close to the intake and covered by simple spring-operated doors which open when the pressure in the intake duct drops below ambient pressure at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MeTDr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MeTDr.jpg&quot; alt=&quot;AV-8B air intake&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AV-8B air intake (picture &lt;a href=&quot;http://farm3.staticflickr.com/2019/1703063822_753090f2d5_z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). The upper two doors are open while the lower three are closed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ideal area of a jet intake varies with flight speed. At low speed, it needs to be large so the amount of air swallowed by the engine can be supplied without too much resistance. At high speed, a big intake captures and compresses more air than the engine needs, which increases drag. Especially fighter jets need an intake which is optimized for high speed flight, and in consequence much of the engine power is needed to suck in enough air during the take-off run. Adding doors which are sucked open in that condition will add another pathway for air to reach the engine, which in turn will help to avoid a &lt;a href=&quot;https://aviation.stackexchange.com/questions/13118/what-is-qualitative-relationship-between-surge-line-stage-characteristic-and-th&quot;&gt;compressor surge&lt;/a&gt; and improves thrust at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no detail knowledge of the MiG-21 intake, but it appears to me that the anti-surge doors are only open at low speed and high engine RPM. At high speed, the pressure in the intake duct is a lot higher than the ambient pressure and the doors are firmly closed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-25T02:05:29.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24601" PostTypeId="2" ParentId="24579" CreationDate="2016-01-25T02:32:48.560" Score="6" Body="&lt;p&gt;Your question shows that you understand the issue already very well, and more detailed fractions of the single components depend on the particular airframe and engine, so my answer will not add much insight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only detail I can add is a plot of tire friction coefficient over speed. Unfortunately, I do not know the source of it; I collected it sometime in the past and never found a reason to doubt its validity. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/uW35x.png&quot; alt=&quot;tire friction coefficient&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, &lt;a href=&quot;http://flightsafety.org/files/alar_bn8-4-braking.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt; might be helpful. Below I copied Figure 3 from it, because it comes closest to answering your question. But keep in mind that the details depend on the particular aircraft and its systems, as well as runway condition, wind speed, tire and brake condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iQ0XE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iQ0XE.png&quot; alt=&quot;Typical deceleration forces during landing roll&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical deceleration forces during landing roll, from &lt;a href=&quot;http://flightsafety.org/files/alar_bn8-4-braking.pdf&quot; rel=&quot;noreferrer&quot;&gt;this document&lt;/a&gt;. Note that the aerodynamic drag with spoilers plus reverse thrust at high speed produce already more deceleration than what is desired at low auto brake setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to find the overall contribution of each braking component, compare the areas under their respective plot lines.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-25T02:32:48.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24602" PostTypeId="2" ParentId="24573" CreationDate="2016-01-25T03:12:24.233" Score="3" Body="&lt;p&gt;Some British aircraft carriers have ski-jumps at the end of their flight decks.  These allow aircraft that are rolling forward already (but too slow to sustain flight) to convert some of their forward velocity into vertical speed, in effect &quot;lobbing&quot; them into the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously if their engines were not providing thrust, they would soon get wet, but it would take longer to hit the water than if they had just rolled off a flat deck.  This gives the aircraft extra time to accelerate to the speed required to sustain flight, and allows a shorter flight deck (so smaller ship, which means cheaper)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on your frame of reference, you could say that the aircraft &quot;fall&quot; of the end of the ski jump.  They certainly have a negative vertical acceleration for a small amount of time, until the airspeed is high enough for the wings to totally counter gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_deck#Ski-jump_ramp&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Flight_deck#Ski-jump_ramp&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13161" LastActivityDate="2016-01-25T03:12:24.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24603" PostTypeId="1" AcceptedAnswerId="24611" CreationDate="2016-01-25T05:07:49.800" Score="6" ViewCount="991" Body="&lt;p&gt;I assume that the thrust of engines on the two sides must be kept exactly equal otherwise the plane would start yawing. What mechanism is used to prevent this from happening?&lt;/p&gt;&#xA;" OwnerUserId="13164" LastActivityDate="2016-01-25T15:48:23.850" Title="How is thrust of engines on the two sides of an airplane kept exactly equal to prevent yawing?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24604" PostTypeId="1" CreationDate="2016-01-25T06:15:20.720" Score="11" ViewCount="2402" Body="&lt;p&gt;Recently a Boeing 747 aborted a take off while still on the ground due to the failure of one engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can a Boeing 747 take off fully loaded on 3 engines?&lt;/p&gt;&#xA;" OwnerUserId="13165" LastEditorUserId="19" LastEditDate="2016-06-27T08:00:49.587" LastActivityDate="2016-06-27T08:00:49.587" Title="Can a Boeing 747 take off fully loaded on 3 engines?" Tags="&lt;safety&gt;&lt;aircraft-performance&gt;&lt;boeing-747&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24605" PostTypeId="1" AcceptedAnswerId="24609" CreationDate="2016-01-25T06:27:56.403" Score="5" ViewCount="1394" Body="&lt;p&gt;While watching this very interesting short movie:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/kT7qrYi8R_M?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; &#xA;I noticed that for some turns pilot uses overbanking like at 1:25. Basically in a turns more than 90 of bank is used. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you explain how it works and how to use it and what is the advantage compared with regular steep turns? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have CPL but I was never thought such maneuvering. Can it be used in SEP aircraft or glider with just a couple of G?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the end of the movie looks like 5G is used for slowing airplane for landing. 5G is pulled and jet instantly slows from 300 to 260. I don't know if brakes are extended though. Can it be used in SEP as well? Like dive to the runway pull some G, slowdown and land?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="19" LastEditDate="2017-03-03T22:33:06.520" LastActivityDate="2017-03-03T22:33:06.520" Title="Can manoeuvres like overbanking and high G braking be used in a single propeller aircraft?" Tags="&lt;aerodynamics&gt;&lt;aerobatics&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24606" PostTypeId="1" CreationDate="2016-01-25T07:07:15.403" Score="11" ViewCount="3445" Body="&lt;p&gt;Inverted flight as a part of manouveres, dogfights, acrobatics is fairly common but my question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are any aircraft capable of sustained inverted flight without losing altitude? e.g. Could you fly 10 mins inverted at the same flight level?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To clarify: I'm not wondering about engines, fuel systems, air-frame strength etc. Fundamentally there's no reason why those systems cannot be engineered to be robust against inverted flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I'm curious about is specifically the aerofoil itself. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;i.e. As far as I can see, you'd need to balance the gravity vector with lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ergo, are aircraft wings generally capable of providing enough compensating lift in the &quot;wrong&quot; direction to balance gravity? Are all / most fighters / arerobatic certified craft capable of this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We'd need an aerofoil that can provide a lift vector pointed in the +z direction normally but changable to a large vector pointing in the -z direction in response to a flight surface deflection?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="22726" LastEditDate="2018-10-16T02:59:03.640" LastActivityDate="2020-06-18T04:17:54.693" Title="Are aircraft capable of sustained inverted flight at constant altitude?" Tags="&lt;aerodynamics&gt;&lt;theory&gt;&lt;inverted-flight&gt;" AnswerCount="5" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24608" PostTypeId="2" ParentId="24606" CreationDate="2016-01-25T07:19:14.180" Score="13" Body="&lt;p&gt;Yes they are! Aerobatic aircraft can have symmetrical wing to improve inverted performance. So with these aircraft there is no any problem at all. Other agile aircraft, gliders can fly inverted as well. Of course is far from optimal but possible. Don't forget that lift depends of angle of attack as well. So if you fly inverted angle of attack and drag will be bigger to compensate for a &quot;wrong&quot; wing profile.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-01-25T07:19:14.180" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24609" PostTypeId="2" ParentId="24605" CreationDate="2016-01-25T07:30:23.213" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can you explain how it works and how to use it and what is the advantage compared with regular steep turns?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He needs to turn &lt;em&gt;and start to descent&lt;/em&gt;. Note, that the two moments he's overbanking he's flying over ridges and wants to descent to the valley behind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now when you want to lower the nose in a turn you need to bank more so you still have the desired lateral lift, but less vertical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But he's so fast that he needs &lt;em&gt;negative&lt;/em&gt; vertical lift component, and since the wings are producing positive lift to make the turn, he needs to bank more than 90° to get it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I have CPL but I was never thought such maneuvering. Can it be used in SEP aircraft or glider with just a couple of G?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is a positive G manoeuvre and you can do the same with, say, 2G, so technically yes. However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;You have no use for it. He's flying 420–480 knots. At 420 knots, a 1G (meaning 1G lateral, so 1.41G total at 45° bank) turn will have rate 2.6°/s and radius 4759 m. But in a SEP you might be flying, say, 120 knots and then 1G turn will have rate 9.1°/s and radius 388 m. That, of course, applies to vertical turns as well. So where he needs to push -1G, and thus overbank, you would do with reducing to, say, 0.5G, and thus still normal side up.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You would probably loose spatial awareness rather quickly if you are not trained in aerobatics. The fighter pilots train a lot to be able to handle the plane at these high Gs and unusual attitudes. Without training, it will get confusing pretty quickly.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Your attitude indicator will likely tumble. The fighters have attitude indicators carefully designed not to, but your average mechanical one in something like C172 almost surely will. That is not a problem in itself—aerobatic pilots just cage it and fly purely on external references—but you need to be aware of it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The fighter has a G-meter, but in a typical SEP plane you don't. But if you fly below $V_A$, the wing will stall before exceeding the structural limit, so you can do without.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;During aerobatics, such, or similar manoeuvres may be performed. For example in Red Bull Air Race turns are usually executed at 90° bank (to use all the lift for the change of direction). The plane climbs a bit to store some speed in height, since turns are tighter at slower speed, then makes the hard turn, during which it has 0G vertical and the vertical speed decays and it changes from climb to descent and then it levels from the descent in the gate height and with all its speed back.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At the end of the movie looks like 5G is used for slowing airplane for landing. 5G is pulled and jet instantly slows from 300 to 260.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The induced drag is proportional to coefficient of lift. So when the wings are requested to generate a lot of lift, they also generate a lot of drag. Especially since this might have been enough to pull the delta wings of the Typhoon to the vortex lift regime, where it generates even more drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe part of the reason to fly such sharp turn here is to fly the pattern at modest size despite the high speed and the deceleration is just a nice side-effect. The speed brake would be enough to slow down, and still needs to be used as 260 knots is still about twice the landing speed.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-01-25T07:53:38.620" LastActivityDate="2016-01-25T07:53:38.620" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24610" PostTypeId="2" ParentId="24606" CreationDate="2016-01-25T07:50:08.140" Score="10" Body="&lt;p&gt;Most aircraft use a cambered airfoil. Such an airfoil only gives you a higher stall speed, otherwise it will just cope fine with prolonged inverted flight. The wing's twist will most likely increase the induced drag since the circulation distribution over span is designed for upright flight, and maybe the airfoil will operate outside of its laminar bucket (if its polar has one), so viscous drag will be higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the wing uses a symmetric airfoil and has no washout, like in some aerobatic aircraft, the aircraft will perform identically in both attitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real limit to prolonged inverted operation is the fuel system and, on some engines, the lubrication. If both are designed for prolonged inverted flight, only the fuel level and the physical condition of the pilot will limit the &lt;a href=&quot;https://en.wikipedia.org/wiki/Milo_Burcham&quot; rel=&quot;nofollow&quot;&gt;duration of inverted flight&lt;/a&gt;. It is much more comfortable when your body weight is supported by a comfy seat than by two narrow straps running over your shoulders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The higher stall speed will translate into a higher speed for the minimum power and minimum drag optima, so an aircraft which could keep its altitude in regular flight might have too little power for sustained inverted flight. Also, the trim range of the elevator might be too small to trim the stick forces. In inverted flight the sideslip-induced rolling moment will have the wrong sign, so sideslipping will make you roll into the wind. But if you tolerate all this and engine power is sufficient (which should be true for all fighters since WW II), flying inverted at the same altitude is no particular problem.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-01T21:06:59.760" LastActivityDate="2016-02-01T21:06:59.760" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24611" PostTypeId="2" ParentId="24603" CreationDate="2016-01-25T08:54:33.210" Score="11" Body="&lt;p&gt;It isn't. The rudder is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, if there is asymmetry in thrust, the plane will yaw. And there &lt;em&gt;is&lt;/em&gt; asymmetry in thrust. The engine thrust decreases slightly with wear and the engines are often worn out differently. There are effects like &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot;&gt;P-factor&lt;/a&gt; that shift the thrust axis depending on speed and attitude. And of course an engine may fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So thrust asymmetry happens and needs to be compensated. And it is compensated by generating some sideways force with the rudder. Either by pilot pushing the pedal, or by applying trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @mins mentions, there are also effects that can cause asymmetry of &lt;em&gt;drag&lt;/em&gt;, e.g. icing, and there are situations where the aircraft intentionally needs to fly somewhat sideways, e.g. cross-wind take-off and landing, so rudder is needed for many other things too. And when it's there, it can compensate thrust asymmetry (often, though, the engine failure dictates the minimum size of the vertical stabilizer and rudder).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, that P-factor occurs in single-engine propeller aircraft too, so they also have some thrust asymmetry.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-01-25T08:54:33.210" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24612" PostTypeId="2" ParentId="24604" CreationDate="2016-01-25T08:57:14.760" Score="3" Body="&lt;p&gt;Seems Boeing can even commence takeoff run with three engines: &lt;a href=&quot;http://www.avherald.com/h?article=492675e0&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;http://www.avherald.com/h?article=492675e0&amp;amp;opt=0&lt;/a&gt; What do regulations say about this?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-01-25T08:57:14.760" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24614" PostTypeId="2" ParentId="24573" CreationDate="2016-01-25T09:49:50.180" Score="6" Body="&lt;h2&gt;Short answer: yes, but...&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There are already a number of good answers and examples that, while unprobable (in the sense of &quot;requiring a specific combination of factors&quot;) and dangerous in most of the cases, it is definitely really possible (since it happened).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Adding an historical example&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;At the beginning of commercial aviation, unreliable planes carried paper mail (a.k.a. post, letters) in daredevil conditions.&#xA;In between 1927 and 1929, &lt;a href=&quot;https://en.wikipedia.org/wiki/Jean_Mermoz&quot;&gt;Jean Mermoz&lt;/a&gt; was trying to open a route across the &lt;a href=&quot;https://en.wikipedia.org/wiki/Andes&quot;&gt;Andes&lt;/a&gt;. He and his mechanic stranded at high altitude after an incident, rode into a precipice to gain enough speed to fly again.  This has been widely documented for decades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See for example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.sps-aviation.com/story_issue.asp?Article=726&quot;&gt;Jean Mermoz (1901 - 1936) - SP's Aviation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;He rode an updraft that carried the plane through a high mountain&#xA;  pass, but then a downdraft slammed the aircraft onto a plateau at&#xA;  12,000 feet. Though the small machine suffered only mild damage and&#xA;  was still airworthy, there wasn’t enough take-off run available on the&#xA;  plateau. Mermoz cleared a rough path to the edge of the precipice and&#xA;  they removed whatever they could from the aircraft. They strapped&#xA;  themselves in and Mermoz just rolled off the mountain hoping to gain&#xA;  enough flying speed before hitting the ground. They succeeded;&#xA;  otherwise it would have been certain death.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.globalaviator.co.za/History/aviators.htm&quot;&gt;Famous Aviators | 10 famous aviators&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Mermoz next tackled shortening the Argentina-to-Chile route; pilots had to make a thousand-mile detour to get around the Andes. With mechanic Alexandre Collenot, Mermoz set out in a Latécoère 25 monoplane and found an updraft that carried them through a mountain pass, but a downdraft smashed the aircraft onto a plateau at 12,000 feet. After determining that they could not hike out, Mermoz cleared a crude path to the edge of the precipice and removed from the aircraft anything that wasn’t bolted down. He and Collenot strapped themselves in, and Mermoz got the airplane rolling down the path.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In effect, they dove off the mountain, and Mermoz pointed the nose straight down, hoping to gain flying speed. Again, luck was with him.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13166" LastActivityDate="2016-01-25T09:49:50.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24615" PostTypeId="1" AcceptedAnswerId="24639" CreationDate="2016-01-25T10:07:57.503" Score="7" ViewCount="1954" Body="&lt;p&gt;Many planes allow the use of ULD containers to store hold luggage: such luggage is placed into the containers, then the containers are stored in the hold of the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many advantages to this, as explained here: &lt;a href=&quot;https://aviation.stackexchange.com/questions/17612/why-is-luggage-required-to-be-loaded-in-containers/17617#17617&quot;&gt;Why is luggage required to be loaded in containers?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some airlines do not use ULD containers even when that is possible. I have in mind Easyjet on their A320-family planes, which don't use containers, at least on some flights, even though the planes definitely can handle them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What could be the possible reasons for this? Given the high emphasis on saving every single penny they can, I suppose they have tried both approaches and come to the conclusion that not using ULDs is actually somehow cheaper than using them, which seems counter-intuitive:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;it should take longer to load and unload luggage one by one than just move containers in&lt;/li&gt;&#xA;&lt;li&gt;more manipulations increases the risk of damage to the luggage&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Possible reasons I can guess at (but not verify) are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;loading the containers is actually not so much faster, with containers possibly getting stuck or some similar problem?&lt;/li&gt;&#xA;&lt;li&gt;loading containers requires more equipment, and turns out to be more expensive for this reason&lt;/li&gt;&#xA;&lt;li&gt;it depends on the amount of luggage being carried?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Does anyone have any insights on this?&lt;/p&gt;&#xA;" OwnerUserId="3313" LastEditorUserId="3313" LastEditDate="2019-08-13T07:47:45.507" LastActivityDate="2019-08-13T07:47:45.507" Title="Why do some airlines not use containers for luggage?" Tags="&lt;ground-operations&gt;&lt;low-cost-carrier&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="24616" PostTypeId="2" ParentId="24573" CreationDate="2016-01-25T11:44:37.197" Score="7" Body="&lt;p&gt;I'm surprised to see &lt;a href=&quot;https://en.wikipedia.org/wiki/Courchevel_Altiport&quot; rel=&quot;nofollow noreferrer&quot;&gt;Courchevel Altiport&lt;/a&gt; being only mentioned in comments in this question. While this is not exactly a free fall, the middle part of the runway has a significant slope (18%), which contributes toward accelerating the planes taking off (as well as slowing down the landing planes).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/L2B7B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/L2B7B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One similarity with a free fall is that once the plane reaches the slope, the pilot &lt;a href=&quot;http://www.myaustrianblog.at/en/2014/09/an-eye-witness-tells-the-story-of-the-first-flight-to-courchevel-part-2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;cannot&lt;/a&gt; do &lt;a href=&quot;https://en.wikipedia.org/wiki/Rejected_takeoff&quot; rel=&quot;nofollow noreferrer&quot;&gt;RTO&lt;/a&gt; anymore, because of a short remaining distance and additional acceleration from the slope:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And that’s where we come to the ‘dilemma’ on this runway. Once the DASH 7 has started moving there, there’s no turning back: it just has to take off. Aborting a take-off on a runway this steep is absolutely unthinkable. We could no longer bring the aircraft to a standstill, and I don’t even want to think about the consequences of that…&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12397" LastEditorUserId="12397" LastEditDate="2016-01-25T11:55:04.540" LastActivityDate="2016-01-25T11:55:04.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24617" PostTypeId="1" CreationDate="2016-01-25T11:52:12.317" Score="11" ViewCount="878" Body="&lt;p&gt;Some not very busy airports can have no even a minor incident for years and accident probably won't happen in a major airport during several decades. Training of course is done sometimes. I don't know how often though. This has to be the most boring or the best job if you wan't nothing to do. I think you can spend all your career without putting out single real fire or doing real rescue. &#xA;So what do firefighters do day to day?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8466" LastEditDate="2016-01-25T12:43:29.277" LastActivityDate="2016-05-07T22:48:54.737" Title="What do firefighters do on ordinary days?" Tags="&lt;airport&gt;&lt;fire&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24620" PostTypeId="2" ParentId="24468" CreationDate="2016-01-25T14:31:22.797" Score="8" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Yes, you can work on your own plane, if:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I. You are performing maintenance work under proper supervision, &lt;strong&gt;&lt;em&gt;or&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;II. You are performing &lt;em&gt;preventive maintenance&lt;/em&gt;, and each of the following are true:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You are a certificated pilot (except sport pilot),&lt;/li&gt;&#xA;&lt;li&gt;You either &lt;em&gt;own&lt;/em&gt; &lt;strong&gt;or&lt;/strong&gt; &lt;em&gt;operate&lt;/em&gt; the aircraft in question, and&lt;/li&gt;&#xA;&lt;li&gt;The aircraft is operated under part 91.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Long Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43&quot; rel=&quot;nofollow&quot;&gt;14 CFR 43&lt;/a&gt; regulates aircraft maintenance for those aircraft with a U.S. airworthiness certificate, but not for experimental aircraft (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_11&quot; rel=&quot;nofollow&quot;&gt;§43.1 Applicability&lt;/a&gt;). For the purposes of this answer, I will use the term &quot;aircraft maintenance work&quot; to refer to any and all maintenance work on U.S. certificated aircraft that might fall under the legal definition of maintenance, preventive maintenance, and alterations. This does not include inspections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_13&quot; rel=&quot;nofollow&quot;&gt;§43.3&lt;/a&gt; regulates &lt;em&gt;who&lt;/em&gt; is authorized to perform aircraft maintenance work. Aircraft maintenance work is subdivided into maintenance, preventive maintenance, rebuilding, and alterations. For the purposes of this question, we are interested in two of the many description of who may perform aircraft maintenance work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first is found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_13&quot; rel=&quot;nofollow&quot;&gt;§43.3 (d)&lt;/a&gt;, emphasis mine:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) &lt;strong&gt;A person working under the supervision of a holder of a mechanic&#xA;  or repairman certificate&lt;/strong&gt; may perform the maintenance, preventive&#xA;  maintenance, and alterations that his supervisor is authorized to&#xA;  perform, if the supervisor personally observes the work being done to&#xA;  the extent necessary to ensure that it is being done properly and if&#xA;  the supervisor is readily available, in person, for consultation.&#xA;  However, this paragraph does not authorize the performance of any&#xA;  inspection required by Part 91 or Part 125 of this chapter or any&#xA;  inspection performed after a major repair or alteration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, &lt;em&gt;anyone&lt;/em&gt; can perform aircraft maintenance work under proper supervision. In your case, if you are working under an authorized mechanic who properly supervises you and signs off the work, yes, you can perform aircraft maintenance work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second is found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_13&quot; rel=&quot;nofollow&quot;&gt;§43.3 (g)&lt;/a&gt;, emphasis mine:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(g) Except for holders of a sport pilot certificate, &lt;strong&gt;the holder of a&#xA;  pilot certificate issued under part 61&lt;/strong&gt; may perform preventive&#xA;  maintenance &lt;strong&gt;on any aircraft owned or operated by that pilot&lt;/strong&gt; which is&#xA;  &lt;em&gt;not used under part 121, 129, or 135&lt;/em&gt; of this chapter. The holder of a&#xA;  sport pilot certificate may perform preventive maintenance on an&#xA;  aircraft owned or operated by that pilot and issued a special&#xA;  airworthiness certificate in the light-sport category.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is more complex. If we are to assume that you are the holder of a pilot certificate issued under part 61—for example a Private Pilot certificate—then you meet that part of the qualification. If you own your own aircraft, in whole or in shares, then you also meet that part of the qualification.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, you may also qualify if you only &lt;em&gt;operate&lt;/em&gt; the aircraft regardless of ownership. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=09fcee836993713ed6b1bd64cd26665c&amp;amp;mc=true&amp;amp;node=se14.1.1_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt; defines &lt;em&gt;Operate&lt;/em&gt; as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Operate&lt;/em&gt;, with respect to aircraft, means use, cause to use or&#xA;  authorize to use aircraft, for the purpose (except as provided in&#xA;  §91.13 of this chapter) of air navigation &lt;strong&gt;including the piloting of&#xA;  aircraft&lt;/strong&gt;, with or without the right of legal control (as owner,&#xA;  lessee, or otherwise).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sub&gt;(Note that &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=09fcee836993713ed6b1bd64cd26665c&amp;amp;mc=true&amp;amp;node=se14.2.91_113&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;§91.13&lt;/a&gt; defines careless or reckless operation. In other words, if you use an aircraft carelessly or recklessly you are not actually operating it according to the legal definition and so do not have preventative maintenance privileges for that aircraft. Now you know.)&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if you own, pilot, or otherwise &lt;em&gt;operate&lt;/em&gt; the aircraft, you may have preventive maintenance privileges. The final qualification will be whether you operate the aircraft under part 91—which &lt;em&gt;would&lt;/em&gt; give you preventive maintenance privileges—or under parts 121, 129, or 135—which would generally &lt;em&gt;deny&lt;/em&gt; you preventive maintenance privileges. Note that parts 121, 129, and 135 refer to scheduled or on-demand passenger or freight operations available to the general public, to put it simply.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, some of the answers here imply that you are not authorized to perform preventive maintenance if the aircraft you own or operate is used &lt;em&gt;for commercial purposes&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;This is not the case.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many commercial purposes are allowed under part 91, including rental, flight instruction, aerial patrols, sightseeing, business transportation (think business jets), skydiving, and glider or banner towing, among others. If you otherwise meet the above qualifications and operate an aircraft for such purposes, you are legally authorized to perform preventive maintenance.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This leaves us with the question of what constitutes preventive maintenance. The legal list is found in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#ap14.1.43_117.a&quot; rel=&quot;nofollow&quot;&gt;14 CFR 43 Appendix A (c)&lt;/a&gt; and other answers have done a good job of outlining that, so I won't go into it further.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-08T16:00:49.913" LastActivityDate="2016-03-08T16:00:49.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24621" PostTypeId="2" ParentId="24573" CreationDate="2016-01-25T15:39:59.770" Score="2" Body="&lt;p&gt;I see no reason why it should not be possible if you have enough speed to clear the cliff and keep the nose pointed into the relative wind. In this 0 g maneuver the wings will not stall as long as no lift is being generated. If there is sufficient clearance to gain enough speed to reach a flyable speed and pull up before hitting the ground, it should be ok (not considering practicality). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make a good paper airplane and drop it forward-end facing down, it will fly without a problem (if you made the plane properly)&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2016-01-25T15:39:59.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24622" PostTypeId="2" ParentId="24603" CreationDate="2016-01-25T15:48:23.850" Score="1" Body="&lt;p&gt;This depends on the airframe and where the engines are mounted. The father inboard the engines the less of an issue a slight variation in thrust will cause. But as mentioned the rudder is the general correction for this yaw.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest thing I can think of (and its not really for thrust balance although that is a byproduct of its function) is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Propeller_synchronization&quot; rel=&quot;nofollow&quot;&gt;Synchronizer/Synchronizer&lt;/a&gt; which can be found on some multi engine propeller planes. These devices are mainly to prevent harmonic beats from becoming irritating to the occupants to do so they keep the propellors spinning at near identical RPM's. If you engines are in tune and generating about the same power you should get near identical thrust from them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.hilmerby.com/md80/engsync.html&quot; rel=&quot;nofollow&quot;&gt;MD80 did have an engine sync system&lt;/a&gt; that was able to match RPM's of the N1 or N2 stages of the jets. It seems that this may have &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/58148/&quot; rel=&quot;nofollow&quot;&gt;been mainly for noise&lt;/a&gt; but symmetrical thrust would also have been a byproduct more or less.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an &lt;a href=&quot;http://www.google.com/patents/US6611748&quot; rel=&quot;nofollow&quot;&gt;interesting patent on engine sync systems&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-01-25T15:48:23.850" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24623" PostTypeId="2" ParentId="24606" CreationDate="2016-01-25T15:54:58.547" Score="1" Body="&lt;p&gt;When at the top of a loop, you would normally still have positive g. The issue here is to fly inverted sustainably at -1 g. With a symmetric wing (most fighters and some aerobatic planes) this would be easier as it won't try to create lift towards the earth in that instance &lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2016-01-25T15:54:58.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24625" PostTypeId="1" AcceptedAnswerId="24626" CreationDate="2016-01-25T16:27:48.700" Score="6" ViewCount="1264" Body="&lt;p&gt;For short haul flights, airlines fly with BASIC CREW.&#xA;For long haul flights, the crew must be composed for another crew or &quot;extra&quot; crew members, less than a crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the designation of the crew, that comprises more than the minimum number required to operate the aeroplane?&#xA;For example: 2 captains and 2 FOs; 1 relief pilot; 2 captains and 1 FO.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="1696" LastEditDate="2016-01-25T16:59:55.497" LastActivityDate="2016-01-25T20:23:38.670" Title="What is the name for a flight crew that includes extra members for a longer flight?" Tags="&lt;airline-operations&gt;&lt;terminology&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24626" PostTypeId="2" ParentId="24625" CreationDate="2016-01-25T17:24:04.110" Score="8" Body="&lt;p&gt;A crew that consists of the basic required cockpit crew for the aircraft plus relief crew for long flights is called an &quot;&lt;strong&gt;augmented flight crew&lt;/strong&gt;.&quot; As far as I know, this designation is used by ICAO, the FAA, and the EASA (and likely others.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/safety/fatiguemanagement/FRMS%20Tools/Annex6_Pt1_AttA.pdf&quot; rel=&quot;noreferrer&quot;&gt;This ICAO document&lt;/a&gt; defines augmented flight crew as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Augmented flight crew.&lt;/strong&gt; A flight crew that comprises more than the minimum number required to operate the aeroplane and in which each flight crew member can leave his or her assigned post and be replaced by another appropriately qualified flight crew member for the purpose of in-flight rest.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA's Federal Aviation Regulations define it nearly identically in &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/117.3&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 117.3&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Augmented flightcrew&lt;/em&gt; means a flightcrew that has more than the minimum number of flightcrew members required by the airplane type certificate to operate the aircraft to allow a flightcrew member to be replaced by another qualified flightcrew member for in-flight rest.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2016-01-25T20:23:38.670" LastActivityDate="2016-01-25T20:23:38.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24627" PostTypeId="1" AcceptedAnswerId="24630" CreationDate="2016-01-25T17:40:31.473" Score="0" ViewCount="161" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cCrh1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cCrh1.jpg&quot; alt=&quot;Trailind edge&quot;&gt;&lt;/a&gt;&#xA;Under the trailing edge, there are 3 features, as seen in the picture. What's the name and the purpose of them?&#xA;The chord line is the distance between the leading and trailing edge.&#xA;What's the name of the upper and the lower surface of a wing?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-01-25T18:12:39.670" Title="Some wing parts designation" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-01-25T18:46:11.923" ContentLicense="CC BY-SA 3.0" />
  <row Id="24628" PostTypeId="2" ParentId="24606" CreationDate="2016-01-25T18:03:40.847" Score="5" Body="&lt;p&gt;I realize you explicitly stated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To clarify: I'm not wondering about engines, fuel systems, air-frame&#xA;  strength etc. Fundamentally there's no reason why those systems cannot&#xA;  be engineered to be robust against inverted flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But I'm going to answer for part of this because it does seem to be the limiting factor of your question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main problem with inverted flight is not aerodynamic but propulsive.  Most aircraft fuel tanks require gravity to feed fuel to the engine.  Military and high performance aircraft typically include some mechanisms for maintaining fuel flow during negative G maneuvers like inverted flight.  However, there are usually very strict time restrictions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the B-1B bomber possesses only a single fuel tank able to operate under negative G maneuvers.  During normal flight fuel is pumped from gravity fed tanks into this special fuel tank.  Then during the negative G maneuvers only fuel from this special tank is available for continued engine operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means in practice is that aircraft performing any negative G maneuver starts a count-down clock.  When the clock reaches 0 its engine(s) die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is a very bad thing during normally powered flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The amount of time any particular aircraft has is dependent upon its particular fuel tank design.&lt;/p&gt;&#xA;" OwnerUserId="7526" LastActivityDate="2016-01-25T18:03:40.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24629" PostTypeId="1" AcceptedAnswerId="24638" CreationDate="2016-01-25T18:03:53.627" Score="18" ViewCount="2101" Body="&lt;p&gt;Let's start with the following knowns (please correct me if I am wrong about any):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The braking force provided by the wheel brakes is much larger than that by the thrust reversers&lt;/li&gt;&#xA;&lt;li&gt;One &lt;s&gt;is not allowed to&lt;/s&gt; does not take credit for reversers when calculating landing distance in most aircraft. (A few exceptions exist) &lt;/li&gt;&#xA;&lt;li&gt;Thrust reversers add quite significantly to the weight and complexity of engines&lt;/li&gt;&#xA;&lt;li&gt;An improperly deployed thrust reverser can be critically dangerous and hence many redundant systems must be provided to prevent unwanted deployment&lt;/li&gt;&#xA;&lt;li&gt;Modern civillian aircraft never rely on reverse thrust during flight&lt;/li&gt;&#xA;&lt;li&gt;In the history of aviation incidents quite a few have been related to reverser problems or procedure errors. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;In the light of this why aren't more large civilian aircraft designed that use only wheel brakes + spoilers to do all their braking?&lt;/em&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;More specifically, suppose you had to re-assign the braking force provided by the reversers in the initial rollout to spoliers alone how much more spoiler area would one need to provide? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, spoilers + wheelbrakes seem far more docile and benign than the complexity and risks associated with reverse thrust?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What gives? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PS.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the any modern large passenger jet aircraft that don't have reversers at all?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2016-01-26T07:35:44.023" LastActivityDate="2018-03-26T21:07:14.317" Title="Why do modern jetliners provide Thrust Reversers at all in their design decisions?" Tags="&lt;aircraft-design&gt;&lt;landing&gt;&lt;thrust-reverser&gt;&lt;braking&gt;&lt;spoilers&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24630" PostTypeId="2" ParentId="24627" CreationDate="2016-01-25T18:11:34.353" Score="0" Body="&lt;p&gt;The three bodies are the housings for the flap actuators and they do just that. There is no special name for the upper and lower wing surfaces that I know of or can find, just &quot;upper&quot; and &quot;lower&quot;.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-01-25T18:11:34.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24631" PostTypeId="2" ParentId="24627" CreationDate="2016-01-25T18:12:39.670" Score="3" Body="&lt;p&gt;The sharp pods are called anti-shock bodies or flap track fairings. See &lt;a href=&quot;https://aviation.stackexchange.com/questions/7955/what-is-the-purpose-of-the-sharp-pods-under-airliner-wings&quot;&gt;this question&lt;/a&gt; for further information. Simply put, htey are there to reduce drag- transonic drag by smoothly varying the cross sectional area (Whitcomb Area rule) and by covering the flap actuators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The straight line connecting the wing leading and trailing edges is called chord line; the distance between them is called chord length (both are usually called chord).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The upper and lower wing sufraces are called, well, upper surface and lower surface of wing.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-25T18:12:39.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24632" PostTypeId="2" ParentId="24604" CreationDate="2016-01-25T18:13:14.143" Score="3" Body="&lt;p&gt;You would have to define &quot;fully loaded&quot; but in general, yes you can take on three engines. It is dangerous to fly on three engines because the thrust is imbalanced. Therefore, it is highly preferable to abort, if that is an option.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-01-25T18:13:14.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24633" PostTypeId="1" AcceptedAnswerId="24634" CreationDate="2016-01-25T18:28:28.313" Score="30" ViewCount="4819" Body="&lt;p&gt;Attitude indicators (artificial horizons) use a gyro to display pitch and bank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering if it would work to use a ball half full of liquid to replace the artificial horizon (using the water level as reference)? &lt;/p&gt;&#xA;" OwnerUserId="7427" LastEditorUserId="9276" LastEditDate="2016-01-26T15:00:55.780" LastActivityDate="2017-05-21T15:20:19.957" Title="Can we replace an attitude indicator with a ball half full of liquid?" Tags="&lt;flight-instruments&gt;&lt;attitude&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24634" PostTypeId="2" ParentId="24633" CreationDate="2016-01-25T18:31:20.803" Score="68" Body="&lt;p&gt;Nope.  In a perfectly flown turn, the ball of liquid would appear to indicate level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might argue that it could replace the &quot;ball&quot; of a turn &amp;amp; bank indicator, but that's about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would also be tough to read in turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this YouTube video showing &lt;a href=&quot;https://www.youtube.com/watch?v=V9pvG_ZSnCc&quot; rel=&quot;noreferrer&quot;&gt;Bob Hoover pouring iced tea&lt;/a&gt; while flying the plane through a roll, even while inverted.  Your liquid would behave similarly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vKuzc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vKuzc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="52" LastEditorUserId="14897" LastEditDate="2017-05-21T15:20:19.957" LastActivityDate="2017-05-21T15:20:19.957" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24635" PostTypeId="2" ParentId="24629" CreationDate="2016-01-25T18:36:52.457" Score="7" Body="&lt;p&gt;The added complexity is a valid point. However, the additional braking option provides enough benefits to offset the added cost. Also, it is not accurate that credit is never given for reverse thrust. Per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=se14.1.25_1109&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §25.109&lt;/a&gt;, when calculating accelerate-stop distance, reverse thrust is not considered for a dry runway, but:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;May be included as an additional means of deceleration using recommended reverse thrust procedures when determining the accelerate-stop distance on a wet runway&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So at least from an FAA certification standpoint, reverse thrust is considered as a benefit in wet conditions, which is generally the more critical case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, the wheel brakes provide the majority of the braking force. But that is also a function of your second point. Credit is not always allowed for the reversers, so that means their use merely reduces stopping distance. It is often preferable from an operations standpoint to not use up the entire runway when landing. Exiting the runway earlier can reduce delays and taxi time, and makes room for the next aircraft in line for that runway. If a longer landing roll is still acceptable, the thrust reversers help to reduce the strain on the brakes. While modern brakes are much improved over older designs, they are still an item that needs replacing after use. Harder braking also results in higher brake temperatures, which may require extra time for the brakes to cool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's helpful to have an extra layer of safety in landing distance calculations. If you calculate landing distance that is just within the available distance, there are still many failures that can prevent the aircraft from stopping. The thrust reversers offer additional braking force that can offset unplanned deficiencies in other areas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/24530/1696&quot;&gt;Other options&lt;/a&gt; for providing braking force have their own problems. For an example, &lt;a href=&quot;http://www.b737.org.uk/flightcontrols.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;look at the spoilers on the 737 NG&lt;/a&gt;. You can see that they already occupy all of the available spanwise area. That means the chordwise area would need to be increased. This would also increase weight and complexity. Additional panel area would be needed, and the supporting systems would need to be reinforced. Also, while thrust reversers offer some amount of braking force at any speed, the effect from spoilers drops off more significantly at slower speeds.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-01-25T19:00:54.790" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24636" PostTypeId="2" ParentId="24617" CreationDate="2016-01-25T19:02:14.853" Score="10" Body="&lt;p&gt;Calling them &quot;firefighters&quot; is accurate but they can respond to all sorts of incidents, not just fires (in the USA, even outside airports it's common for firefighters to respond to purely medical emergencies). On top of that, there's also training, maintenance and keeping physically fit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.abc.net.au/news/2015-05-07/a-day-in-the-life-of-an-airport-firefighter-hobart/6450310&quot;&gt;This&lt;/a&gt; is from a firefighter at Hobart Airport in Australia:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aviation firefighters do more than wait for airplane fires, they&#xA;  also attend to other incidents, such as motor vehicle accidents, fuel&#xA;  spills, hazardous material incidents and first-aid in the terminal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&quot;A lot of our working day is routine and there are different types of&#xA;  things that we need do every day regarding our equipment, servicing&#xA;  all of our equipment, checking it over ...,&quot; he said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And &lt;a href=&quot;http://your.heathrow.com/behind-the-scenes-with-an-airport-firefighter/&quot;&gt;this&lt;/a&gt; is from one at Heathrow:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We don’t really have an average day. We attend to all sorts of&#xA;  incidents. We attend to anything that is life-threating at the airport&#xA;  or on the roads around it; this could include a heart attack air or&#xA;  land-side, a drug mule incident where a passenger has transported&#xA;  drugs within their body and has ended up in a serious condition, or a&#xA;  car crash that we have to cut a victim out of.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;We all have set duties to do every day and night including practical&#xA;  and theoretical training, testing and inspections, and cleaning of&#xA;  vehicles and equipment. The crews have to keep physically fit so we&#xA;  give them time for physical training and provide facilities to do&#xA;  this.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-01-25T19:02:14.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24637" PostTypeId="2" ParentId="15537" CreationDate="2016-01-25T19:16:37.230" Score="7" Body="&lt;p&gt;Since replacing a propeller with the same propeller that is in the Type Certificate is not a major repair, the FAR(s) (CFR Title 14) that most apply are 43.7 and (assuming the airplane is under Part 91) 91.407.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_17&quot; rel=&quot;noreferrer&quot; title=&quot;43.7 states&quot;&gt;43.7 states&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable to the Administrator, except as noted in §43.16. He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. If special equipment or test apparatus is recommended by the manufacturer involved, he must use that equipment or apparatus or its equivalent acceptable to the Administrator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So you must follow the maintenance manual and put the airplane back in a state at least as good as original. If you think that putting them both on does not qualify to satisfy this requirement, then you should do them one at a time. If it does satisfy this, then in that case, 91.407 comes into play, which &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e07c724e60b2c3a055d69cad3fc6ac5d&amp;amp;mc=true&amp;amp;node=se14.2.91_1407&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;states&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may operate any aircraft that has undergone maintenance, preventive maintenance, rebuilding, or alteration unless—&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) It has been approved for return to service by a person authorized under §43.7 of this chapter; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) The maintenance record entry required by §43.9 or §43.11, as applicable, of this chapter has been made.&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;(b) No person may carry any person (other than crewmembers) in an aircraft that has been maintained, rebuilt, or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies the aircraft, makes an operational check of the maintenance performed or alteration made, and logs the flight in the aircraft records.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The aircraft does not have to be flown as required by paragraph (b) of this section if, prior to flight, ground tests, inspection, or both show conclusively that the maintenance, preventive maintenance, rebuilding, or alteration has not appreciably changed the flight characteristics or substantially affected the flight operation of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would argue that a propeller change cannot be satisfied by (c) above and does require a flight test. However, there is nothing that &lt;em&gt;requires&lt;/em&gt; separate flight tests &lt;strong&gt;UNLESS&lt;/strong&gt; the maintenance manual requires it, in which case part 43.7(a) from above comes into play. But as a &quot;fail safe&quot; a good run-up on the ground at high throttle with the brakes applied, followed by an inspection of the work can give good confidence in the work prior to the flight test.&lt;/p&gt;&#xA;" OwnerUserId="12936" LastEditorUserId="12936" LastEditDate="2016-01-26T14:24:30.850" LastActivityDate="2016-01-26T14:24:30.850" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24638" PostTypeId="2" ParentId="24629" CreationDate="2016-01-25T19:18:16.867" Score="20" Body="&lt;p&gt;There are  a couple of reason for the presence of thrust reversers:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;To reduce wear on the brakes.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To provide a margin of safety (for example in wet conditions).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In 1995, NASA carried out a survey on airlines &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19950014289.pdf&quot; rel=&quot;noreferrer&quot;&gt;Why Do Airlines Want and Use Thrust Reversers?&lt;/a&gt;. The results of the survey, though dated, give an indication of presence of thrust reversers.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The main reasons given by the airlines was to provide additional stopping force in adverse weather and to reduce brake wear.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The first question posed to the airlines was &amp;quot;why do we have thrust reversers?&amp;quot; (...) The number one reason given by the airlines was to provide additional stopping forces in adverse weather conditions (i.e. on wet, slushy or slippery runways). The airlines also use thrust reversers to reduce brake wear and to provide directional control and additional safety margins during an aborted takeoff (RTO).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;According to the airlines, the thrust reversers were there because they wanted them there. This meshes with the fact that the thrust reversers are not used in calculating stopping distances during certification.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the airlines were asked who they perceived as the principal organization behind the installation of thrust reversers on commercial transport aircraft, the airlines responded that they were. That is, the&#xA;aircraft manufacturers put the systems on board the airplanes because the&#xA;airlines want them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Most airlines recommend using the thrust reversers early in the landing to minimize braking.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The airlines weigh the economic benefits of using the thrust reversers (and engine wear) against the use of brakes and the results seem to indicate a significant amount of money saved by using thrust reversers. The report notes:&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;... the savings in brake system costs due to the use of thrust reversers was estimated. The results show that the total yearly savings in brake system costs is about \$8.6 million, or an average of about $17,700 per airplane for airline 17.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Though this is almost certainly an exaggeration, the numbers indicate that the airlines would definitely prefer thrust reversers over increased braking.&lt;/p&gt;&#xA;&lt;p&gt;In the end, the reverse thrust can be important in reducing the runway requirements in case of a wet runway. In 1999, a Qantas 747 &lt;a href=&quot;https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/fsa/2002/nov/24-31.pdf&quot; rel=&quot;noreferrer&quot;&gt;overran the (wet) runway in Bangkok and landed up in a golf course&lt;/a&gt;. Qantas has used only idle reverse thrust rather than full power during the landing as per the operational procedure. The &lt;a href=&quot;https://www.atsb.gov.au/media/24447/aair199904538_001.pdf&quot; rel=&quot;noreferrer&quot;&gt;official accident report&lt;/a&gt; included data from Boeing 747-400 Flight Crew Training Manual, which stated that,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Immediate initiation of reverse thrust at main gear touchdown and full reverse thrust reduce brake usage, thus minimising brake temperatures.&lt;/p&gt;&#xA;&lt;p&gt;To minimise wear of carbon brakes, minimise the number of brake applications. Use maximum reverse thrust and operate the autobrakes normally.&lt;/p&gt;&#xA;&lt;p&gt;The importance of establishing the desired reverse thrust level as soon as possible after touchdown to minimise brake temperatures, tyre and brake wear, and to reduce stopping distance on very slippery runways cannot be overemphasised..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As a result, Qantas revised their operational procedures, requiring full reverse thrust. Brake wear is an important reason for having thrust reversers. For example, &lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-stopping-the-a380-27549065/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;in Airbus A380&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;... unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Aerospace_146&quot; rel=&quot;noreferrer&quot;&gt;BAe 146&lt;/a&gt; lacks a thrust reverser; it makes do with an airbrake in the tail and spoilers all along the wing for braking (which should give an indication of how much spoilers is required to eliminate reversers). The 146 got away with that because of the low touchdown speeds (~90 kt) and the huge airbrake, which is not avialble in the other commercial airliners. For the same amount of spoiler area in other commercial airliners (in absence of airbrakes), they (spoilers) would occupy most of the wing surface, increasing weight and complexity. Some &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_ERJ_145_family&quot; rel=&quot;noreferrer&quot;&gt;Embraer ERJ 145&lt;/a&gt;s also lack thrust reversers (they are optional).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-03-26T21:07:14.317" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24639" PostTypeId="2" ParentId="24615" CreationDate="2016-01-25T19:35:31.660" Score="4" Body="&lt;p&gt;There are some siuations where it is better to load the luggage individually than in ULDs.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The airports served by the flight should have the necessary infrastructure to handle them. As an example, a number of carriers have outsourced their ULD logistics, which are &lt;a href=&quot;http://www.jettainer.com/index.php?id=93&amp;amp;tx_ttnews[tt_news]=115&amp;amp;cHash=836042d05ca2844b836b11ba1b4f05db&quot; rel=&quot;nofollow&quot;&gt;available only in a few&lt;/a&gt; (usually long haul) destinations. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The ULDs are fast and economical (compared to putting luggage directly) only if there is some minimum amount of luggage. For short routes, the use of ULDs may not offer any significant benefits compared to direct loading due to the amount of luggage. Plus, the ULDs themselves add (some) weight, which should be small compared to the luggage carried.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another thing is that for connecting flights (i.e. only a few passengers are transferred), it is better to have the luggage in the hold rather than in ULDs as the transfer time required would be lower (U don't have to open the ULD to get their baggage).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I suspect the main reason is economics. &lt;a href=&quot;http://www.bdpinternational.com/wp/wp-content/uploads/Handling-Airfreight-101-2.pdf&quot; rel=&quot;nofollow&quot;&gt;This presentation&lt;/a&gt; talks about the pricing of ULDs and describes two rates:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A base rate for use of each ULD.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;An another rate for weights above the allowable weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, if the airline is 'renting' the ULD (as I suspect most of them are), it doesn't make sense for them from an economic point of view to 'rent' an ULD unless the amount of luggage is above some threshold value, which is satisfied only in long routes or the number of passengers is more. So, low cost carriers may totally skip using ULDs and charge their customers for extra luggage to discourage them from carrying it (they can use the space and weight for cargo instead, though I'm not sure about it).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-25T19:35:31.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24641" PostTypeId="1" AcceptedAnswerId="24644" CreationDate="2016-01-25T20:46:27.017" Score="11" ViewCount="11568" Body="&lt;p&gt;The Reynolds-Number $Re$ is defined as $Re = \frac{c \cdot L \cdot \rho}{\mu} = \frac{c \cdot L}{\nu}$, with&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the velocity $c~\left[ \frac{m}{s} \right]$,&lt;/li&gt;&#xA;&lt;li&gt;the reference length $L~\left[ m \right]$,&lt;/li&gt;&#xA;&lt;li&gt;the density $\rho~\left[ \frac{kg}{m^3} \right]$&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$\rho = \frac{p}{R \cdot T}$ for ideal gases&lt;/li&gt;&#xA;&lt;li&gt;pressure $p~\left[ Pa \right] = \left[ \frac{kg}{m \cdot s^2} \right]$&lt;/li&gt;&#xA;&lt;li&gt;temperature $T~\left[ K \right]$&lt;/li&gt;&#xA;&lt;li&gt;ideal gas constant $R~\left[ \frac{J}{kg \cdot K} \right] = \left[ \frac{m^2}{K \cdot s^2} \right]$&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;the dynamic viscosity $\mu~\left[ \frac{kg}{m \cdot s} \right]$ and&lt;/li&gt;&#xA;&lt;li&gt;the kinematic viscosity $\nu~\left[ \frac{m^2}{s} \right]$, $\nu = \frac{\mu}{\rho}$.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From my understanding, drag increases with decreasing Reynolds-Numbers. Hence, drag increases with an increasing kinematic viscosity (see e.g. this &lt;a href=&quot;http://dx.doi.org/10.1007/978-3-642-34539-5&quot; rel=&quot;nofollow&quot;&gt;book&lt;/a&gt;):  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Relation between altitude and kinematic viscosity according to the &lt;a href=&quot;http://www.iso.org/iso/catalogue_detail?csnumber=7472&quot; rel=&quot;nofollow&quot;&gt;ISA&lt;/a&gt; (International Standard Atmosphere)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;With an increasing altitude, the density of the air decreases.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The dynamic viscosity decreases with an increasing altitude of up to $11'000~m$, then stays constant to $25'000~m$ and increases from an altitude of more than $25'000~m$.&lt;br&gt;&#xA;This is based on &lt;a href=&quot;https://www.grc.nasa.gov/www/BGH/viscosity.html&quot; rel=&quot;nofollow&quot;&gt;Sutherland's Formula&lt;/a&gt; for ideal gases, which in turn relies on the air temperature.&lt;br&gt;&#xA;According to ISA, air temperature decreases with an increasing altitude of up to $11'000~m$, then stays constant to $25'000~m$ and increases from an altitude of more than $25'000~m$.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dividing $\mu$ by $\rho$, one can see that the kinematic viscosity increases with an increasing altitude.&lt;br&gt;&#xA;See for example &lt;a href=&quot;http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/atmos/atmtab.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; or &lt;a href=&quot;http://aero.stanford.edu/stdatm.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; for precise data.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;In summary, the Reynolds-Number decreases with an increasing altitude, which means that drag increases with an increasing altitude - assuming velocity and reference length are constant.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Does an airplane really experience more drag, the higher its flying altitude is, assuming otherwise constant parameters?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When researching for this question, one often stumbles across the statement that drag decreases with increasing altitude due to the decreasing density. However, no one seems to take the kinematic density into account.&lt;br&gt;&#xA;Are there trustworthy charts available indicating drag over altitude?&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="19" LastEditorDisplayName="user12485" LastEditDate="2016-06-27T08:00:26.807" LastActivityDate="2021-01-17T18:20:41.877" Title="What is the relation between an airplane's altitude and the drag it is experiencing?" Tags="&lt;aerodynamics&gt;&lt;drag&gt;&lt;aircraft-physics&gt;&lt;reynolds-number&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24642" PostTypeId="2" ParentId="24615" CreationDate="2016-01-25T21:44:38.663" Score="8" Body="&lt;p&gt;In addition to the reasons given by @aeroalias, cargo containers also waste space. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.fly-car.de/local/media/formulare/airbusindustries.pdf&quot; rel=&quot;noreferrer&quot;&gt;A320/321 Operator's Manual&lt;/a&gt;:&#xA;&lt;img src=&quot;https://i.stack.imgur.com/py7JK.jpg&quot; alt=&quot;A320 container layout&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A320 can hold up to 7 containers. The A319/320/321 do not use the standard LD3 containers. They use the slightly smaller AKH container.&#xA;&lt;img src=&quot;https://i.stack.imgur.com/OscJk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each of these has a volume of 3.7 m&lt;sup&gt;3&lt;/sup&gt;, so seven of them totals 25.9 m&lt;sup&gt;3&lt;/sup&gt;. When bulk loaded the A320 has 37.28 m&lt;sup&gt;3&lt;/sup&gt; of cargo space. That's almost 44% more room. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-01-25T21:44:38.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24644" PostTypeId="2" ParentId="24641" CreationDate="2016-01-25T22:12:12.160" Score="6" Body="&lt;p&gt;Yes, it does - skin friction increases with an increasing altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The mechanism is linked more to temperature than to density, but the reasoning in your question is correct. There might be a few cases where viscous drag increases with Reynolds number (like laminar airfoils which lose their laminar bucket when the Reynolds number goes up), but in general the observation is true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First a plot from Sighard Hoerners book &lt;a href=&quot;https://openlibrary.org/works/OL5289632W/Fluid-dynamic_drag&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fluid Dynamic Drag&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Uiy4S.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Uiy4S.png&quot; alt=&quot;Flow properties over altitude&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow properties over altitude, from page 1-11 in Fluid Dynamic Drag, 1965 edition. The ratio of the actual Reynolds number to the Reynolds number at sea level $\frac{R}{R_0}$ shows a clear downward trend over altitude (which is plotted on the x axis). At 60,000 ft the Reynolds number at the same flow speed is only 12% of that on the ground. If you look at the same dynamic pressure, you have to correct that by the square root of the density ratio $\frac{\rho}{\rho_0}$, which is 0.3 at 60,000 ft. In total, the aircraft will fly in 60.000 ft at 40% of the Reynolds number at sea level when the dynamic pressure stays constant. Lift is proportional to dynamic pressure, therefore it is best to keep the dynamic pressure constant for the comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the viscous drag over Reynolds number: From the same book I copied a plot of lots of experimental data which shows the trend nicely:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/quK76.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/quK76.png&quot; alt=&quot;Skin friction over Reynolds number&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Skin friction over Reynolds number, from page 2-6 in Fluid Dynamic Drag. Note that both axes are logarithmic to produce a nearly linear trend line. k denotes a correction for a flow which starts laminar but then turns turbulent when the critical Reynolds number is reached (critical = &lt;em&gt;kritisch&lt;/em&gt; in German, hence the k).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For even more details I recommend &lt;a href=&quot;http://adg.stanford.edu/aa241/drag/skinfriction.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt; from Stanford.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your comments helped me to understand the source of your doubts. Drag and lift are proportional to dynamic pressure $q$, and this in turn is the product of speed $v$ squared and density $\rho$: $$q = \frac{v^2}{2}\cdot\rho$$&#xA;Reduce density, and you reduce drag. But this will also reduce lift. In the end, you want to support the same aircraft mass at lower density, so you need to do something to get lift back to its old level despite the drop in density. You do this by increasing speed. You restore the same dynamic pressure, in other words. Now the drag is also back to its old level, plus some more. &lt;a href=&quot;https://en.wikipedia.org/wiki/Isentropic_process&quot; rel=&quot;nofollow noreferrer&quot;&gt;Isentropic&lt;/a&gt; expansion means that temperature drops when density drops, and the thermodynamic law of isentropic expansion describes what happens to air in the atmosphere (isentropic = no change in entropy). Lower temperature means higher viscosity. Moving at the same dynamic pressure in lower temperature will generally cause more viscous drag.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-26T07:35:23.610" LastActivityDate="2016-01-26T07:35:23.610" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24645" PostTypeId="2" ParentId="24604" CreationDate="2016-01-25T22:57:52.117" Score="14" Body="&lt;p&gt;The short answer as detailed to some degree in previous answers and comments is that a 747 can takeoff if the engine fails after the V&lt;sub&gt;1&lt;/sub&gt; speed is reached but not if the failure occurs before reaching V&lt;sub&gt;1&lt;/sub&gt;. Unfortunately, in my opinion, the owner of one of the answers has deleted his answer, which while perhaps imperfect did provide useful information, and perhaps as important will remove the comments.&lt;/p&gt;&#xA;&lt;p&gt;It's best to understand the V&lt;sub&gt;1&lt;/sub&gt; speed within the context of a balanced field takeoff. See &lt;a href=&quot;https://en.wikipedia.org/wiki/Balanced_field_takeoff&quot; rel=&quot;noreferrer&quot;&gt;this Wikipedia article for a full explanation&lt;/a&gt;. The first two paragraphs are:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A balanced field takeoff is a condition where the accelerate-stop distance required (ASDR) is equal to the takeoff distance required (TODR) for the aircraft weight, engine thrust, aircraft configuration and runway condition.&lt;a href=&quot;https://en.wikipedia.org/wiki/Balanced_field_takeoff&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt; For a given aircraft weight, engine thrust, aircraft configuration, and runway condition, the shortest runway length that complies with safety regulations is the balanced field length.&lt;/p&gt;&#xA;&lt;p&gt;The rejected takeoff initial actions speed V1, or critical engine-failure recognition speed (Vcef),is the fastest speed at which the pilot must take the first actions to reject the takeoff (RTO). At speeds below V&lt;sub&gt;1&lt;/sub&gt; the aircraft may be brought to a halt before the end of the runway. At V&lt;sub&gt;1&lt;/sub&gt; the pilot must continue the takeoff even if an emergency is recognized.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Let's translate this into a practical situation using a 747-200 with old steam gauges. Prior to engine start five plastic bugs would be positioned around the rim of the airspeed indicator: the first at V&lt;sub&gt;1&lt;/sub&gt;, the second at V&lt;sub&gt;R&lt;/sub&gt;, the third at V&lt;sub&gt;2&lt;/sub&gt;, and the last two at speeds not relevant to our discussion. We're rushing down the runway at takeoff power and all goes well. When we reach V&lt;sub&gt;1&lt;/sub&gt;, the PNF says &amp;quot;V&lt;sub&gt;1&lt;/sub&gt;&amp;quot; and the PF takes his hand off the thrust levers (he had them there in case of an abort). When we reach V&lt;sub&gt;R&lt;/sub&gt;, the PNF says &amp;quot;rotate&amp;quot; and the PF brings the yoke back briskly but smoothly to a pre-determined nose attitude (usually 12 or 13 degrees). When the landing gear is off the runway, you'll hear the gear down lock retract unlocking the gear up lever. When the PNF sees a positive climb rate on the vertical speed, he'll say &amp;quot;positive rate&amp;quot;, the PF will call &amp;quot;gear up&amp;quot;, the PNF will move the gear lever to up. When the airplane reaches V&lt;sub&gt;2&lt;/sub&gt; the PNF will say &amp;quot;V&lt;sub&gt;2&lt;/sub&gt;&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;The important thing to remember here is that if there had been an engine failure after V&lt;sub&gt;1&lt;/sub&gt;, the only difference would have been that the first person to know which engine had failed would have called &amp;quot;engine failure #1&amp;quot; say. On the old 3-crew airplanes, that would usually be the f.e. Even if the engine was burning, no action would be taken until after V&lt;sub&gt;2&lt;/sub&gt;, and probably not until after you had a clean airplane.&lt;/p&gt;&#xA;&lt;p&gt;Just as a matter of information, here are some V speeds for a 747-200 with P&amp;amp;W JT9D-7Q engines for a Flaps 10 takeoff at 840,000 lbs:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;V&lt;sub&gt;1&lt;/sub&gt; 168 kts&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;R&lt;/sub&gt; 181 kts&lt;/li&gt;&#xA;&lt;li&gt;V&lt;sub&gt;2&lt;/sub&gt; 189 kts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Now for an abort. An abort below 80 kts is no big deal. Between there and 100 kts gets more interesting. Above 100 kts it is not to be taken lightly, and an abort at say, 150 kts, is a bonafide emergency. A friend of mine had to do one of those, and he blew all of the 16 tires that had brakes. In my view, if an engine failure occurs within a few knots either way of V&lt;sub&gt;1&lt;/sub&gt;, you're better off flying.&lt;/p&gt;&#xA;&lt;p&gt;To quote from &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20080525-0&quot; rel=&quot;noreferrer&quot;&gt;an accident report&lt;/a&gt; in which I was involved in the investigation:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The bang and the loss of power occurred around V1 speed. Two seconds after the bang, all four engines were brought back to idle, and braking action was initiated. The thrust reversers were not deployed.&#xA;The aircraft came to a stop 300 m after the end of runway 20, above a railroad embankment. The aircraft was severely damaged; it broke in three parts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="394" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-25T23:04:27.310" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24647" PostTypeId="2" ParentId="24605" CreationDate="2016-01-25T23:30:19.797" Score="2" Body="&lt;p&gt;Another reason would be that pilots tend to dislike negative g-forces. Also, a fighter tends to have a -3 g limit while having a +6 to 9 g limit, so even if the roll would take time, one can still turn sharper. And it's more fun &lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2016-01-25T23:30:19.797" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24648" PostTypeId="1" AcceptedAnswerId="24660" CreationDate="2016-01-26T05:14:41.053" Score="21" ViewCount="3997" Body="&lt;p&gt;I was flying from Canada to Jamaica, and just past Florida the plane turned 90 degrees towards Nassau. It then continued over Cuba. Is this because of the situation between Cuba and the United States? It appears the plane must enter Cuban airspace from international airspace. But I have heard some planes can enter Cuba via corridors from the US. I am confused over this situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was flight TS0373 on 17Jan2016.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xXiBm.jpg&quot; alt=&quot;flight map&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8774" LastEditorUserId="753" LastEditDate="2016-01-27T16:17:24.790" LastActivityDate="2016-01-27T16:17:24.790" Title="What is the reason for this route while flying from USA over Cuba?" Tags="&lt;flight-path&gt;&lt;map&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24649" PostTypeId="1" AcceptedAnswerId="24652" CreationDate="2016-01-26T05:38:56.117" Score="5" ViewCount="3345" Body="&lt;p&gt;Consider a large commercial aircraft coming in for landing. The exact part I'm interested in is &lt;strong&gt;the flare&lt;/strong&gt; (where the aircraft noses up yet does not actually go higher above the ground), with flaps extended, but before any ground effect comes into play.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Compared to normal cruise, does the Lift-to-Drag ratio increase, decrease, or not change much at all?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Increasing angle-of-attack increases both the lift and the drag, but probably not by the same proportions. I'm not really sure which way the curve goes for a typical airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there's a really harsh complication: the flare also results in &lt;strong&gt;the engines pointing upwards too.&lt;/strong&gt; This means that some &quot;lift&quot; is generated directly by the engines' vertical component of thrust. It's not really lift; a more accurate way to say it is the wings don't need to produce as much lift as before, because the engines do a direct part in helping to counteract gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So that might suggest the L/D in fact decreases, which seems so counter-intuitive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual numbers for the L/D at both stages of flight would be the most rock-solid answer possible. But I wonder if the L/D's cited by the manufacturers are derived from a simple wind-tunnel test (at different AoA and flap configuration) or if they actually take into account the upwards-pointing engines and their typical thrust during flare (which would be best measured as a percentage of aircraft weight at that point, and the mess gets messy).&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="12720" LastEditDate="2016-01-26T13:31:05.780" LastActivityDate="2016-01-26T14:41:12.683" Title="For a large commercial plane on landing, does the L/D ratio increase, decrease, or not change much?" Tags="&lt;aerodynamics&gt;&lt;commercial-aviation&gt;&lt;lift&gt;&lt;drag&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24650" PostTypeId="1" AcceptedAnswerId="24656" CreationDate="2016-01-26T06:57:05.037" Score="4" ViewCount="516" Body="&lt;p&gt;I am an avionics technician (c-130) in the USAF and plan on learning to fly helicopters when I separate in about a year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have debated whether or not to pursue a &lt;a href=&quot;https://en.wikipedia.org/wiki/General_radiotelephone_operator_license&quot; rel=&quot;nofollow&quot;&gt;GROL&lt;/a&gt; or possibly &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_maintenance_technician&quot; rel=&quot;nofollow&quot;&gt;A&amp;amp;P&lt;/a&gt;.  From what I know, these are generally intended for maintainers/technicians rather than aviators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, would there be any benefit to having a GROL or related license for an aspiring helicopter pilot?&lt;/p&gt;&#xA;" OwnerUserId="13182" LastEditorUserId="5517" LastEditDate="2016-01-26T15:42:46.137" LastActivityDate="2016-01-26T15:56:37.633" Title="Is there a benefit to a pilot/aviator having an FCC GROL license?" Tags="&lt;pilots&gt;&lt;student-pilot&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24651" PostTypeId="2" ParentId="18730" CreationDate="2016-01-26T07:18:33.953" Score="7" Body="&lt;p&gt;This is my own take on this interesting question. I've been reading about Soviet space and aviation realms for what seems like a lifetime. Here is the general knowledge I've accumulated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lion's share of resources went to the military, which meant they got the best aircraft engines. Factories are expensive, so &lt;strong&gt;they tended to use the same military engines&lt;/strong&gt; on civil aircraft that optimally needed a different engine design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, most &quot;new&quot; (post-WW2) military planes wanted turbojets for supersonic speed, whereas civil planes would benefit much more from turbofans (a pretty new concept at the time). So many jet airliners got turbojets too for several decades IIRC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For most post-WW2 Soviet history, petrol was very cheap and so the economic incentive like we see today just didn't exist. This cheap petrol also existed in the US for a time, but the crunch came much earlier (1974 arab oil embargo IIRC, which didn't affect USSR. In fact, the raised oil prices actually benefited USSR selling their native petrol at higher prices). This eventually changed in the 80's IIRC (petrol in Baku drying up), by which time a whole contingent of other economic problems were stacking up and civil aviation just wasn't a priority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Soviet aircraft place more emphasis on being able to takeoff from poor, dirt fields (for military reasons), which adds weight to the landing gear and maybe fuselage frame.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Soviet aircraft place more emphasis on cold-weather durability, which includes not just lower extremes in the envelope, but also just the general operation in temperatures which are on average colder than in US. This adds weight to engines and other parts (I believe hydraulics? plus any moving exterior joints?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;WW2 completely destroyed the Soviet economy. This is sort of going beyond &quot;the reason is poor engines&quot; and giving a reason for the reason, but it is relevant. The exact opposite happened in America, where WW2 was economically a boon that completely reversed the Great Depression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems like there are some more but I can't think of them. Will edit later if necessary.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-01-26T07:24:51.180" LastActivityDate="2016-01-26T07:24:51.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24652" PostTypeId="2" ParentId="24649" CreationDate="2016-01-26T07:47:25.730" Score="10" Body="&lt;p&gt;In the flare you are already in ground effect. Maybe we should compare the final approach with cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is simple: L/D is far worse in approach configuration. The wing buys the increased lifting capacity with a relatively higher drag increase. This is not all bad: If the L/D is too high, a precise landing becomes much harder. Also, some more drag allows you to run the engines above idle, so spooling up for a go-around takes less time. Generally, you want the L/D to be between 5 and 10 for landing. Too much, and the approach becomes too shallow for a precise selection of the touchdown point, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/7711/can-fighter-aircraft-glide/7715#7715&quot;&gt;too little&lt;/a&gt; and you lose too much energy in the flare, so you decelerate too fast in that final phase where sink speed is reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare that to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2999/how-far-can-airplanes-glide/3001#3001&quot;&gt;L/D of modern airliners&lt;/a&gt; in cruise, which is around 16 for designs like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1738/how-does-the-boeing-787-dreamliners-glide-ratio-compare-to-other-airliners/13975#13975&quot;&gt;above 20 for the Boeing 787&lt;/a&gt; or the A350.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can study this cheaply in gliders. Take one with powerful flaps, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASW_20&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASW 20&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASH_25&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASH 25&lt;/a&gt;. Try to land them with all flaps and spoilers fully extended: You will never get to a smooth touchdown, but drop on the wheel somewhere before the flare is complete. Then try to land them with flaps set for slow flight and no spoilers: You need a loooong runway to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lift contribution of the engines during the flare is very moderate. They do not run at full power, and even if they did, their combined thrust would be only maybe 30% of the aircraft weight. Since they don't point straight up, but only by about 10°, the vertical component would be only 5% even at full thrust. In reality, they run at a little above idle, and their lift contribution is only 2% at most.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gLYh5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gLYh5.jpg&quot; alt=&quot;Flap type effectiveness comparison&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flap type effectiveness comparison (picture &lt;a href=&quot;http://www.homebuiltairplanes.com/forums/attachments/aircraft-design-aerodynamics-new-technology/1806d1215373142-maximum-lift-values-flap-types-effectiveness.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). The L/D is only for maximum lift, not at 60% of it which would be more representative for an approach lift coefficient, but the trend to lower L/D with higher maximum lift coefficient should be obvious.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-01-26T12:03:22.853" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24653" PostTypeId="1" AcceptedAnswerId="24655" CreationDate="2016-01-26T08:11:03.513" Score="31" ViewCount="21489" Body="&lt;p&gt;&lt;strong&gt;Clarification:&lt;/strong&gt; It wasn't Air Force One that visited Switzerland, it was the 747-200 E4 carrying Ashton Carter. &lt;a href=&quot;http://www.nzz.ch/zuerich/aktuell/ashton-carter-mit-hochgeruestetem-jumbojet-gelandet-ld.4370&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this thing on top of the plane (In red circle):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rUfzI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rUfzI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On other &quot;Air Force One&quot; Google image searches, I can't find this thing. I know they have more than one 'doomsday-plane', but whats the purpose / use of this thing? &#xA;&lt;a href=&quot;https://i.stack.imgur.com/yPkhE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yPkhE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="15982" LastEditDate="2017-06-25T22:11:37.557" LastActivityDate="2018-09-09T11:56:43.263" Title="What is this on top of the Air Force One?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;us-air-force&gt;&lt;feature-identification&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24654" PostTypeId="2" ParentId="24653" CreationDate="2016-01-26T08:29:17.323" Score="13" Body="&lt;p&gt;That is not simply an E4, but a &quot;B&quot; variant.&#xA;The hump houses a SHF antenna. (&lt;a href=&quot;http://aviamagazine.com/factsheets/aircraft/e4/index.aspx&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;December 1979 a fourth aircraft (75-0125) was added. This aircraft was fitted with the distinctive “Hump” on the back of the upper deck, housing the SHF antenna. It also offered upgraded accommodations, additional shielding, upgraded electronics and new CF-6-50E2 engines. This became known as the E-4B model.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-01-26T08:29:17.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24655" PostTypeId="2" ParentId="24653" CreationDate="2016-01-26T08:32:39.087" Score="44" Body="&lt;p&gt;The aircraft is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_E-4&quot; rel=&quot;noreferrer&quot;&gt;Boeing E-4B Advanced Airborne Command Post&lt;/a&gt; 'Nightwatch', which serves as the survivable mobile command post for the US National Command Authority. The aircraft are based on the same Boeing 747s as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_VC-25&quot; rel=&quot;noreferrer&quot;&gt;VC-25&lt;/a&gt;s used by US President.&lt;/p&gt;&#xA;&lt;p&gt;There are four identical aircraft performing this function in the US. The &amp;quot;bulge&amp;quot; on the top is a radome that houses a steerable SHF SATCOM antenna, as can be seen in the following image.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VrXBF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VrXBF.jpg&quot; alt=&quot;E4B&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.cnet.com/news/aboard-americas-doomsday-command-and-control-plane/&quot; rel=&quot;noreferrer&quot;&gt;cnet.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The following image shows the aircraft systems in a little more detail.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wtnyl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wtnyl.jpg&quot; alt=&quot;E4&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://everythingisahoax.tumblr.com&quot; rel=&quot;noreferrer&quot;&gt;http://everythingisahoax.tumblr.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As a side note, Air Force One refers specifically to USAF aircraft carrying the US President. From &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;US DoT ORDER&#xA;JO 7110.65W &lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the President is aboard a military aircraft, state the name of the military service, followed by the word &amp;quot;One&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;EXAMPLE−&lt;/p&gt;&#xA;&lt;p&gt;“Air Force One.”&lt;/p&gt;&#xA;&lt;p&gt;“Army One.”&lt;/p&gt;&#xA;&lt;p&gt;“Marine One.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For civil aircraft, it is Executive One.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-26T22:29:57.530" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24656" PostTypeId="2" ParentId="24650" CreationDate="2016-01-26T09:04:31.563" Score="2" Body="&lt;p&gt;There's no tangible benefit to having a GROL in getting a pilots license of any kind as getting the license generally confers the right to use aircraft radios. In some places you need to get an RT license for aviation as a separate test, however that's pretty minimal. A GROL is only good for repairing, maintaining, and running certain types of radio stations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An A&amp;amp;P will let you work on airplanes, but it also does not help get a license. An A&amp;amp;P will give you insights into how an airplane works, but you can get those insights without an A&amp;amp;P. Having an A&amp;amp;P and a pilots license might be a different story if you plan to work in remote locations where being able to fix your aircraft when it breaks is useful. It won't help you get a flying job in most places. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-01-26T09:04:31.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24657" PostTypeId="1" CreationDate="2016-01-26T10:46:52.413" Score="7" ViewCount="9946" Body="&lt;p&gt;What's the difference between the ILS Critical Area vs ILS Sensitive Area?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm getting multiple conflicting opinions online.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. I can't decipher from this set of definitions how exactly they differ:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ILS critical area is an area of defined dimensions about the&#xA;  localizer and glide path antennas where vehicles, including aircraft,&#xA;  are excluded during all ILS operations. The critical area is protected&#xA;  because the presence of vehicles and/or aircraft inside its boundaries&#xA;  will cause unacceptable disturbance to the ILS signal-in-space&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;vs&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The ILS sensitive area is an area extending beyond the critical area&#xA;  where the parking and/or movement of vehicles, including aircraft, is&#xA;  controlled to prevent the possibility of unacceptable interference to&#xA;  the ILS signal during ILS operations. The sensitive area is protected&#xA;  against interference caused by large moving objects outside the&#xA;  critical area but still normally within the airfield boundary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;All I can grok is that the critical area seems some subset of the sensitive area? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do I take this to mean no vehicles are allowed in critical area but some smaller vehicles may be allowed in the sensitive area? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="62" LastEditDate="2017-01-23T19:36:08.787" LastActivityDate="2017-01-23T19:36:08.787" Title="What is the difference between the ILS Critical Area and the ILS Sensitive Area?" Tags="&lt;air-traffic-control&gt;&lt;ils&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24659" PostTypeId="2" ParentId="24648" CreationDate="2016-01-26T13:31:05.683" Score="14" Body="&lt;p&gt;There are two large &lt;a href=&quot;https://aviation.stackexchange.com/q/20877/62&quot;&gt;warning areas&lt;/a&gt; there, &lt;a href=&quot;https://skyvector.com/?ll=24.63891616818054,-80.16655446457088&amp;amp;chart=37&amp;amp;zoom=7&quot; rel=&quot;nofollow noreferrer&quot;&gt;W-465 A and B&lt;/a&gt;. Both are active &quot;intermittently&quot; up to 70,000ft. It seems likely that the route was taken to avoid those areas.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-01-26T13:31:05.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24660" PostTypeId="2" ParentId="24648" CreationDate="2016-01-26T14:19:11.070" Score="12" Body="&lt;p&gt;When I flew from TEB to Kingston about 15 years ago in a PC-12, we used &lt;a href=&quot;https://cfs.jeppesen.com/&quot; rel=&quot;noreferrer&quot;&gt;Jeppesen's international trip planning service&lt;/a&gt; to obtain all of the required overflight permits, make landing, customs and fueling arrangements, and provide  weather services. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The route we were provided by Jeppesen (which I don't remember exactly now) required airways in non-US airspace, and had specific entry and exit points in Cuban airspace, probably based on that country's radar and separation requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that OP's aircraft flew FOWEE-URUS-UCA-MLY&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And as you can see from FlightAware, the &lt;a href=&quot;https://flightaware.com/analysis/route.rvt?origin=KMIA&amp;amp;destination=MKJP&quot; rel=&quot;noreferrer&quot;&gt;KMIA-MKJP route&lt;/a&gt; often takes this routing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is not why did the &quot;the plane turned 90 degrees&quot;, but rather why wasn't the plane vectored directly to FOWEE in the first place. The most likely reasons are weather and traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kVQLk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kVQLk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-27T14:40:25.317" LastActivityDate="2016-01-27T14:40:25.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24661" PostTypeId="2" ParentId="24657" CreationDate="2016-01-26T14:29:36.073" Score="5" Body="&lt;p&gt;As you can see from this &lt;a href=&quot;http://cockpitdata.com/Software/ICAO%20Annex%2010%20Volume%201&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Annex 10 image&lt;/a&gt;, the ILS critical Area does indeed lay within the ILS sensitive Area, and its size is dependent on the Category of the ILS approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U04ot.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U04ot.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-01-26T15:37:16.847" LastActivityDate="2016-01-26T15:37:16.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24662" PostTypeId="2" ParentId="24657" CreationDate="2016-01-26T14:35:39.737" Score="8" Body="&lt;p&gt;Basically, yes- critical area is a subset of the sensitive area. However, the terms 'sensitive' and critical' are used interchangeably in many contexts. ICAO itself acknowledges this in the same section (ICAO Annex 10 Volume I Attachment C):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Note 1.— The objective of defining critical and sensitive areas is to afford adequate protection to the ILS. The manner in which the terminology is applied may vary between States. In some States, the term “critical area” is also used to describe the area that is referred to herein as the sensitive area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The determination of the critical and sensitive areas depends on the actual airport and the system in operation. The operator/regulator may simply include the are in critical list if they suspect any interference. For example, &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp1490-appendix-a-6185.htm&quot;&gt;Transport Canada says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Actual critical areas can be defined only by experimentation and experience. When any portion of a designated sensitive area becomes suspect as a likely source of interference, that portion must be included as part of the critical area.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The main difference appears between the critical and sensitive areas appear to be that the size of the critical area is fixed (for a localizer and glide path antenna in an airport) while that of the sensitive area varies with the category of ILS and the aircraft type. In fact, the introduction of A380 led to a &lt;a href=&quot;http://www.icao.int/EURNAT/Other%20Meetings%20Seminars%20and%20Workshops/MISC/A380%20workshop/Assessment%20of%20ILS%20protection%20areas%20impact%20on%20large%20aircraf%20operations%20V1.3%20web.pdf&quot;&gt;reassesment of ILS protection areas&lt;/a&gt;. From Volume I:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2.1.9.3 The size of the sensitive area depends on a number of factors including the type of ILS antenna, the topography, and the size and orientation of man-made objects, including large aircraft and vehicles. ... . Because of the greater potential of the larger types of aircraft for disturbing ILS signals, the sensitive areas for these aircraft&#xA;  extend a considerable distance beyond the critical areas.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vwrAk.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vwrAk.jpg&quot; alt=&quot;ILS critical and sensitive&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from ICAO Annex 10 Volume I Attachment C&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In operational sense, in critical areas, &lt;em&gt;all&lt;/em&gt; the vehicle and aircraft movement is prohibited, while in sensitive areas, the prohibition is limited.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;To protect the critical area, it is necessary to normally prohibit all entry of vehicles and the taxiing or parking of aircraft within this area during all ILS operations. ... With respect to sensitive areas, it may be necessary to exclude some or all moving traffic depending on interference potential and category of operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-26T14:35:39.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24663" PostTypeId="2" ParentId="24649" CreationDate="2016-01-26T14:41:12.683" Score="1" Body="&lt;p&gt;The L/D ratio is usually lesser i.e. worse in landing configuration comapred to cruise. Basically, the high lift devices in the wing trade off some effeciency (L/D) for extra lift. In a sense, this is what you want because you're more concerned with getting more lift at lesser speed at that point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following table from &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a380516.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA Technical Note 1930&lt;/a&gt; gives the change in the L/D ratio in different configurations compared to cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T5D6A.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T5D6A.png&quot; alt=&quot;L/D ratio&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;An Analysis of the effect of Lift-Drag ratio and stalling speed on stalling speed and landing flare characteristics&lt;/em&gt; by J.Calvin Lovell and Stanley Lipson&lt;/p&gt;&#xA;&#xA;&lt;p&gt;NASA used a CV 990 aircraft to carryout low L/D ratio apprach and landing studies, which indicate that under landing conditions, as the flaps are extended, the L/D ratio becomes worse. Data were obtained with 100-percent spoiler (speed-brake) deflection at&#xA;flap settings of 0$^{\circ}$, 10$^{\circ}$, and 27$^{\circ}$ with 100$^{\circ}$ spoiler (speed brake settings). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1mrRX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1mrRX.jpg&quot; alt=&quot;CV 990&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from NASA Technical Note D-6732 &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/87806main_H-672.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Low Lift-to-Drag ratio Approach and Landing studies using a CV-990 Airplane&lt;/em&gt;&lt;/a&gt; by Berwin M. Kock, Fitzhugh L. Fulto11, Jr., and Fred ]· Drinkwater III&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to aerodynamic effects, they went on to use 36$^{\circ}$ flaps and 25 percent of spoilers instead. Data from NASA wind tunnel models also indicates that as the flaps are extended, the L/D ratio decreases. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uxxHc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uxxHc.jpg&quot; alt=&quot;L/D data&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://web.mit.edu/amarch/www/files/March_thesis_SM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Influence of Low-speed Aerodynamic Performance on Airport Community Noise&lt;/em&gt;&lt;/a&gt; by Andrew March; Data from NASA Technical Paper 1580 &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19820007142&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;Low-speed aerodynamic performance of a high-aspect-ratio supercritical-wing transport model equipped with full-span slat and part-span double-slotted flaps&lt;/em&gt;&lt;/a&gt; by Morgan, H. L., Jr. and Paulson, J. W., Jr&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first reference has data for other Boeng aircraft (727,747 etc) which also indicate that the L/D ratio suffers as the flaps are extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a simple sense, we can think like this- the aircraft is flying close to the maximum L/D ratio (for propeller and large bypass commercial jets) during cruise. Any change from this configuration will most probably result in lesser L/D ratio. This is what happens during landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines contribute only a minimal amount to the 'lift' during landing. There are a few reasons for this. The thrust is usually quite a bit smaller than the lift. Added to this, the engines are usually not at their full power during landing of commercial aircraft. Plus, pitch angle is pretty small during landing in normal aircraft. Putting all these together, the contribution of thrust is usually negligible.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-26T14:41:12.683" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24664" PostTypeId="2" ParentId="23810" CreationDate="2016-01-26T15:42:32.733" Score="3" Body="&lt;p&gt;The safety pilot can't log any &lt;em&gt;acting&lt;/em&gt; PIC time but he could still log PIC time as sole manipulator of the controls (if he ever takes the controls, that is).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's from &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2011/walker%20-%20(2011)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;an FAA legal interpretation&lt;/a&gt; (based on &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2009/speranza%20-%20(2009)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this previous one&lt;/a&gt;) that clarifies logging PIC time under IFR without an instrument rating. The interpretation discusses an instrument-rated pilot (&quot;Pilot A&quot;) flying with a non-instrument-rated pilot (&quot;Pilot B&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, acting as PIC and logging PIC are different things, and only Pilot A can &lt;em&gt;act&lt;/em&gt; as PIC under IFR:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA has previously stated that there is a distinction between logging PIC time and acting as a PIC. See &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2009/herman%20-%20(2009)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Herman Interpretation&lt;/a&gt;. To act as a PIC (i.e., the pilot who has final authority and responsibility for the operation and safety of the flight), a pilot must be properly rated in the aircraft and be properly rated and authorized to conduct the flight. In your example of an IFR flight, being properly rated and authorized would include having an instrument rating. Accordingly, only Pilot A may act as the PIC, and Pilot A has final authority and responsibility for the safety of the flight regardless of who is manipulating the controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But you don't need an instrument rating to &lt;em&gt;log&lt;/em&gt; PIC time, as long as you're rated for the aircraft. That means that in simulated instrument conditions the safety pilot (&quot;Pilot B&quot;) can't log any time as acting PIC under 61.51(e)(iii) but he can still log PIC time if he's the sole manipulator of the controls, under 61.51(e)(i):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;for the purpose of logging PIC time under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_151&quot; rel=&quot;nofollow noreferrer&quot;&gt;§61.51(e)&lt;/a&gt;, a pilot must hold ratings for the aircraft rather than for the conditions of flight. Accordingly, Pilot B may log PIC time for the portion of the flight during which Pilot B was the sole manipulator of the controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, Pilot A can log PIC time for the entire flight but Pilot B can log it only for the time spent as sole manipulator. If Pilot B never touches the controls then he can't log any PIC time at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In actual IMC, 61.51(e)(iii) doesn't apply because a safety pilot is only required in simulated IMC. The FAA's conclusion is that if Pilot B takes the controls in actual IMC then he can log both PIC and instrument time, but Pilot A can't log anything:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots A and B are flying in actual IMC conditions, not simulated instrument flight conditions, and the aircraft operation is not one for which &quot;more than one pilot is required under ... the regulations under which the flight is conducted.&quot;  &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2009/speranza%20-%20(2009)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Speranza Interpretation (Dec. 4, 2009)&lt;/a&gt;. Therefore, Pilot A is not acting as a safety pilot and, as was the case in the Speranza Interpretation, being the PIC in this context is not a basis for Pilot A to log flight time under § 61.51 for the portion of the flight being logged by Pilot B as PIC flight time while the sole manipulator of the controls.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pilot A is still &lt;em&gt;acting&lt;/em&gt; as PIC in that case, he just can't &lt;em&gt;log&lt;/em&gt; the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, remember that the FAA interpretation is only about the legality of logging PIC time under IFR. Unless you're a CFII, letting someone without an instrument rating fly under IFR would be very risky, even in VMC. There's a good chance that if something went wrong then the FAA would go after both pilots on the basis of &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_113&quot; rel=&quot;nofollow noreferrer&quot;&gt;91.13&lt;/a&gt; (careless and reckless operation).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="14661" LastEditDate="2018-08-26T21:43:48.090" LastActivityDate="2018-08-26T21:43:48.090" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="24665" PostTypeId="2" ParentId="24650" CreationDate="2016-01-26T15:52:07.703" Score="0" Body="&lt;p&gt;The only FCC license that you might need is the &lt;a href=&quot;http://wireless.fcc.gov/commoperators/index.htm?job=rr&quot; rel=&quot;nofollow&quot;&gt;restricted radiotelephone operator permit (RR)&lt;/a&gt;.  There is no test for the permit but there is a fee.  You'll only need the permit if you intend to fly outside of the united states and communicate with foreign ATC.   &lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-01-26T15:52:07.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24666" PostTypeId="2" ParentId="24650" CreationDate="2016-01-26T15:56:37.633" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;From what I know, these are generally intended for&#xA;  maintainers/technicians rather than aviators.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Correct, an A&amp;amp;P will not help you get a pilots license (aside from maybe gaining a better understanding of how the internals work). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;That said, would there be any benefit to having a GROL or related&#xA;  license for an aspiring helicopter pilot?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is a bit of a different question, to which the answer may be yes, in the sense that an A&amp;amp;P cert can be useful if you are involved in aviation. An A&amp;amp;P could be very valuable to you as an aviator in general. First off if you intend on owning a helicopter you will be able to undercut some of the costs by doing work yourself. As mentioned if you intend on flying in remote places being able to work on your own bird can literally save your life. If you are looking to fly professionally you can always make money on the side doing A&amp;amp;P work (its a pretty high paying profession). I have no idea if it has any bearing but there is a chance it will lower your insurance premiums as well (generally the more certifications you have the lower your insurance  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-01-26T15:56:37.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24667" PostTypeId="1" AcceptedAnswerId="24669" CreationDate="2016-01-26T16:46:40.670" Score="4" ViewCount="1711" Body="&lt;p&gt;If an airliner were to breakup in flight, and a passenger were ejected from the cabin, would it be possible to survive the fall?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume that the aircraft broke up at a cruise altitude 30,000-35,000 feet. If it improved the odds, suppose the person were wearing a heavy winter jacket and a backpack with additional clothing in a plastic bag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is is possible the person could survive the fall? Are there steps the person could take that might increase the chances of survival?&lt;/p&gt;&#xA;" OwnerUserId="12221" LastEditorUserId="12221" LastEditDate="2016-02-28T13:03:43.470" LastActivityDate="2016-02-28T13:03:43.470" Title="Is it possible to survive a free fall from an airliner at cruise altitude?" Tags="&lt;accidents&gt;&lt;passenger&gt;&lt;jet&gt;&lt;hypotheticals&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24669" PostTypeId="2" ParentId="24667" CreationDate="2016-01-26T16:55:21.393" Score="7" Body="&lt;p&gt;Chances are you would not survive but lets explore this a bit more in depth for the sake of education. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.popularmechanics.com/adventure/outdoors/a5045/4344036/&quot; rel=&quot;nofollow&quot;&gt;article from popular mechanics&lt;/a&gt; explores the very issue. There is some research that has gone into the topic of hitting the ground but the research is rarely about cases from the height you are asking about (~30,000ft). Some relevant info &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First off at that altitude you really can't breathe that effectively so hypoxia will be your first concern followed closely by extreme cold.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hitting water:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Studies of bridge-jump survivors indicate that a feet-first,&#xA;  knife-like entry (aka &quot;the pencil&quot;) best optimizes your odds of&#xA;  resurfacing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Hitting the ground:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The question of how to achieve ground contact remains, regrettably,&#xA;  given your predicament, a subject of debate. A 1942 study in the&#xA;  journal War Medicine noted &quot;distribution and compensation of pressure&#xA;  play large parts in the defeat of injury.&quot; Recommendation: wide-body&#xA;  impact. But a 1963 report by the Federal Aviation Agency argued that&#xA;  shifting into the classic sky diver's landing stance—feet together,&#xA;  heels up, flexed knees and hips—best increases survivability.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Your best bet for surviving the airplane break up is if you are stuck in a situation similar to that of &lt;a href=&quot;https://en.wikipedia.org/wiki/Vesna_Vulovi%C4%87&quot; rel=&quot;nofollow&quot;&gt;Vesna Vulović&lt;/a&gt; who did survive the situation you describe. Unfortunately there is some debate as to what actually happened so take the info at face value. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“Speed has never killed anyone. Suddenly becoming stationary, that's&#xA;  what gets you.”  ― Jeremy Clarkson&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-27T15:43:07.237" LastActivityDate="2016-01-27T15:43:07.237" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24670" PostTypeId="2" ParentId="24386" CreationDate="2016-01-26T17:01:26.730" Score="2" Body="&lt;p&gt;The answer is both modelling and/or empirical methods are used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft with a closed loop Flight Control System then the clearance requirements before flight requires that sufficient gain and phase margins exist for the system. For example with Military Aircraft this was defined in &lt;a href=&quot;http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-F/MIL-F-9490D_5297/&quot; rel=&quot;nofollow&quot; title=&quot;MIL-F-9490D&quot;&gt;MIL-F-9490D&lt;/a&gt;. This would involve building mathematical models of the aircraft and control laws and calculating margins from the frequency response of the model. This allows the engineers to analyse the robustness of the system under various tolerance and failure states before flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to analyse stability margins from flight data, but note even the RTSM software referenced in the comments talks about comparing the flight data calculated margin against an a priori model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that Handling Qualities requirements, i.e. saying it is PIO prone, are additional requirements over and above the basic stability requirements. This introduces another feedback path with a pilot in the loop. For this there are additional frequency response parameters to meet, for example average phase rate. Again examples in MIL-Spec requirements &lt;a href=&quot;http://everyspec.com/MIL-SPECS/MIL-SPECS-MIL-F/MIL-F-8785C_5295/&quot; rel=&quot;nofollow&quot;&gt;MIL-F-8785C&lt;/a&gt;, these will all be assessed using mathematical models.  &lt;/p&gt;&#xA;" OwnerUserId="769" LastActivityDate="2016-01-26T17:01:26.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24671" PostTypeId="2" ParentId="24667" CreationDate="2016-01-26T19:12:55.290" Score="3" Body="&lt;p&gt;According to Wikipedia's &lt;a href=&quot;https://en.wikipedia.org/wiki/Terminal_velocity&quot; rel=&quot;nofollow&quot;&gt;article on terminal velocity&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the terminal velocity of a skydiver in a belly-to-earth (i.e., face down) free-fall position is about 195 km/h (122 mph or 54 m/s).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Using &lt;a href=&quot;http://tutor4physics.com/calculators.htm&quot; rel=&quot;nofollow&quot;&gt;this online physics calculator&lt;/a&gt; with&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Acceleration: 98.1 m/s^2 (10G)&lt;br/&gt;&#xA;  Final velocity: 0&lt;br/&gt;&#xA;  Initial velocity: 54 m/s&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I get a deceleration distance of -9.42 meters, or about 31 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can somehow slow down over that distance (&lt;a href=&quot;https://en.wikipedia.org/wiki/Nicholas_Alkemade&quot; rel=&quot;nofollow&quot;&gt;perhaps by hitting a stand of trees and some snow, preferably on a hill side&lt;/a&gt;) you &lt;em&gt;might&lt;/em&gt; make it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: the 10G deceleration is completely arbitrary on my part - I assume it's a reasonably survivable impact depending on what and how you hit.&lt;/p&gt;&#xA;" OwnerUserId="52" LastActivityDate="2016-01-26T19:12:55.290" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24673" PostTypeId="1" CreationDate="2016-01-26T20:51:22.077" Score="10" ViewCount="1347" Body="&lt;p&gt;I was looking at some photos today and came across this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sub&gt;Image &lt;a href=&quot;http://www.airliners.net/photo/Indonesia---Air/Boeing-737-2X9-Adv-Surveiller/1919586/L/&amp;amp;sid=28b379ca97685d0b23e985a0b3a9fcb0&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I noticed four little things in between the horizontal and vertical stabilizer. Could somebody explain me what those are?&lt;/p&gt;&#xA;" OwnerUserId="13195" LastEditorUserId="62" LastEditDate="2016-10-17T13:49:18.130" LastActivityDate="2016-10-17T13:49:18.130" Title="What are these four little things between the horizontal and vertical stabilizer on the B737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24674" PostTypeId="2" ParentId="24673" CreationDate="2016-01-26T21:29:14.220" Score="22" Body="&lt;p&gt;The objects are &lt;a href=&quot;https://aviation.stackexchange.com/q/13876/1696&quot;&gt;vortex generators&lt;/a&gt;. In general, vortex generators serve to introduce turbulence which helps to prevent flow separation. More information &lt;a href=&quot;http://www.b737.org.uk/fuselage.htm#AFT_BODY_VORTEX_GENERATORS&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This was to reduce elevator and elevator tab vibration during flight to increase their hinge bearing service life.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As mentioned on the site, you can see these on any 737 version from the original -100/-200 up through the NG. Better image from same site:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dX0NB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dX0NB.jpg&quot; alt=&quot;View of aft body vortex generators&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-01-26T21:29:14.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24675" PostTypeId="1" AcceptedAnswerId="24678" CreationDate="2016-01-26T23:07:26.110" Score="8" ViewCount="374" Body="&lt;p&gt;In the official &lt;a href=&quot;http://www.icao.int/publications/DOC8643/Pages/Search.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO database&lt;/a&gt; 5 aircraft are marked with an engine count C. What is that supposed to mean? Normally engine count is a number (0,1,2,3...).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C7MYI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C7MYI.png&quot; alt=&quot;ICAO&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4024" LastActivityDate="2016-01-27T00:58:40.727" Title="What does ICAO database &quot;engine count c&quot; mean?" Tags="&lt;icao&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24676" PostTypeId="1" CreationDate="2016-01-26T23:23:31.040" Score="14" ViewCount="1450" Body="&lt;p&gt;Near the end of the movie, &quot;Air Force One&quot;, Harrison Ford is transferred to a C-130, which then changes its call sign to &quot;Air Force One&quot;. My question is, has a president of the US ever flown in a C-130 while in office?&lt;/p&gt;&#xA;" OwnerUserId="11931" LastEditorUserId="15311" LastEditDate="2019-04-14T18:11:18.260" LastActivityDate="2019-04-14T18:11:18.260" Title="Has a C-130 ever been designated as &quot;Air Force One&quot;?" Tags="&lt;aviation-history&gt;&lt;call-sign&gt;&lt;head-of-state-transport&gt;&lt;c-130&gt;&lt;air-force-one&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24678" PostTypeId="2" ParentId="24675" CreationDate="2016-01-27T00:58:40.727" Score="9" Body="&lt;p&gt;I don't know the exact ICAO phraseology, but it certainly seems to describe an aircraft that has two engines &lt;strong&gt;combined&lt;/strong&gt; to a single driveshaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Soloy has trademarked the '&lt;a href=&quot;http://soloy.com/products/fixed-wing/dual-pac/&quot; rel=&quot;noreferrer&quot;&gt;Dual Pac&lt;/a&gt;', a pair of turboprops driving a single shaft through a gearbox. All of the Soloy aircraft there use this powerplant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/6/6c/Gannet_AS.4_NAN9-79.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/go5Wpm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairey_Gannet&quot; rel=&quot;noreferrer&quot;&gt;Fairey Gannet&lt;/a&gt; was a (super cool) anti-submarine aircraft designed in the late 40s. It was powered by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Armstrong_Siddeley_Double_Mamba&quot; rel=&quot;noreferrer&quot;&gt;Armstrong Siddeley Double Mamba&lt;/a&gt; which you could argue was the direct predecessor of the Dual Pac, albeit using a presumably very different gearbox to drive the contra-rotating prop. One half of the Double Mamba could be shut down in flight, and both props would continue to be driven: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Double Mamba engine could be run with one Mamba stopped to conserve fuel and extend endurance for cruise flight. The contra-rotating propellers meant that when only half of the Double Mamba was running there were no thrust asymmetry problems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Armstrong_Siddeley_Double_Mamba&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IZM1I.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="39" LastActivityDate="2016-01-27T00:58:40.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24679" PostTypeId="1" AcceptedAnswerId="24693" CreationDate="2016-01-27T01:53:06.347" Score="14" ViewCount="1367" Body="&lt;p&gt;It is my understanding that vortex generators produce more favorable aerodynamics by delaying flow separation. If this is the case, why do more GA aircraft not have vortex generators?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="22726" LastEditDate="2019-08-23T21:52:02.313" LastActivityDate="2019-08-23T21:52:02.313" Title="Why do most GA aircraft not have vortex generators?" Tags="&lt;aerodynamics&gt;&lt;vortex-generators&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24680" PostTypeId="1" AcceptedAnswerId="24683" CreationDate="2016-01-27T03:03:34.647" Score="36" ViewCount="6551" Body="&lt;p&gt;I don't know of any bird that has a vertical tailfin, but apparently aircraft need them for lateral stability. Why is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I did realize, however, that most fish have a vertical tailfin, or a vertical dorsal fin, or both. What exactly is going on there? Can't see how marine creatures would need lateral stability at low speeds in a thick liquid (compared to air).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If that second paragraph sounds off-topic, let me put it another way. What is it about the air, as opposed to water, that requires this? They are both fluids. One is thicker/more viscous than the other, which seems to imply that the thicker one would require less lateral stability. Yet it seems to be the opposite. I hope this will be taken as a valid on-topic aerodynamics question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(P.S. I'm leaving out stuff like the B-2 Spirit because it uses active dynamic adjustments to stabilize. Its form is inherently unstable.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;IMPORTANT EDIT:&lt;/strong&gt; I should have pointed out the large difference in speed. Birds of course are slow. So were the early Wright flyers. Modern airliners fly much faster, around Mach 0.85. I haven't yet looked up Reynold's Numbers, but it certainly could be the case that the faster ones need lateral stability while the slower one's don't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1 more clarification:&lt;/strong&gt; When I say &quot;stability&quot;, I'm not exactly talking about yaw control. My impression is, just when the plane is flying perfectly straight, there are pressure fluctuations that will cause slips unless there is a large vertical surface area to balance out those fluctuations. I could be wrong, and ultimately I'm trying to find out why most planes seem to need this large vertical area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1 more:&lt;/strong&gt; Here's an example model that seems synonymous: Let's say our airplane achieves yaw with butterfly flaps at wingtips, which are aligned with the center of mass (the flaps and CoM have the same height) so there's no side-effect torques along another axis other than the yaw axis (z axis). Let's assume no backup yaw control is necessary. This craft is meant to cruise at Mach 0.85. Is a vertical fin necessary to achieve passive directional stability about the yaw axis? We should probably consider cross-winds too, even at takeoff/landing.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="8282" LastEditDate="2017-07-28T14:37:34.557" LastActivityDate="2017-07-28T14:37:34.557" Title="Why do aircraft need a vertical tailfin, but birds don't? (and lots of fish do?)" Tags="&lt;aerodynamics&gt;&lt;stability&gt;&lt;vertical-stabilizer&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24683" PostTypeId="2" ParentId="24680" CreationDate="2016-01-27T07:31:35.620" Score="30" Body="&lt;p&gt;Not all of them need a fin:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4K7Rj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4K7Rj.jpg&quot; alt=&quot;Horten IV in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the Horten IV, a flying wing glider that did not need a fin (picture &lt;a href=&quot;http://www.cnc-modell.de/cnc/jpeg/horten4/Img0053.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Instead, it used spoilers at the wingtips to create yawing moments, and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9287/how-does-wing-sweep-increase-aircraft-stability/9292?s=6%7C0.0919#9292&quot;&gt;swept wing&lt;/a&gt; helped in improving its weak directional stability. It could afford to do so because it was a glider. The second prototype of a jet-powered flying wing, the Horten IX V2, suffered a crash when one engine failed and the pilot could not end the resulting spiral dive.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fins on airplanes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Birds have two advantages over airplanes which make a fin superfluous:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A variable geometry wing, where wing span, sweep and incidence can be controlled for each side independently.&lt;/li&gt;&#xA;&lt;li&gt;Propulsion is integrated into the wing, instead of separate power plants which might fail independently.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An extra advantage of birds over older airplane designs lacking a computerized control system is that the bird's brain is wired to adjust the wing on each side subconsciously and continuously. While a fin provides an aircraft with weathervane stability, a bird is inherently indifferent (neither stable nor unstable) and needs continuous tweaking of its wings for directional control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a bird wants to control yaw, it simply adjusts its wingtips such that the drag difference between both creates the desired moment. It can do this by reducing wingspan on one side, which also creates a rolling moment for a coordinated turn. Airplanes unfortunately cannot do the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes need positive directional stability because humans cannot adjust the controls continuously - they need to check maps or work the radio, or maybe just want to relax for a moment. Also, multi-engined designs need a stability margin to compensate the asymmetric thrust resulting from a failed engine. With a fin, the mass of the structure behind the center of gravity now needs a compensating mass ahead of it, and the side area of this forward fuselage is de-stabilizing the aircraft in yaw, requiring yet more area at the vertical tail. This is another problem that birds do not face.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0hxHM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0hxHM.jpg&quot; alt=&quot;B-52H 61-023 on 10.1.1964&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B-52H 61-023 suffered a structural failure of the fin on January 10, 1964, but managed to limp home with almost no lateral stability left. Had it suffered an additional engine failure, it would had crashed (picture &lt;a href=&quot;https://en.m.wikipedia.org/wiki/File:Boeing_B-52_with_no_vertical_stabilizer.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Fins on fish&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The dorsal fin of fish helps in their propulsion by balancing the areas above and below their vertebral column. By wagging the tail, they create a side force which creates a sideslip condition at the dorsal fin, which in turn produces a correcting side force so the body does not roll while swimming. In this it can be compared to the keel of a sailboat. The hydrodynamic forces on a keel counteract the side force from the sail in crosswind conditions. Its main function is to stabilize the fish from the yawing motion caused by their tail fins, and this stabilization in turn improves the efficiency of the motion of the tail fin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An additional function is as a roll sensor. Being located at the maximum girth, it gives the best readings of local sideways motion due to roll. This is the main function in marine mammals where the tail fins are horizontally oriented. In fish which have an adipose fin (located aft of the main fin), this fin is most likely their roll sensor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not used for roll control (except as a sensor in a feedback loop), and cannot because it is not adjustable. Roll control is achieved by the adjustable pelvic fins. It also cannot provide roll stability - this would require it to roll the fish back to its initial attitude after a disturbance. All it can do for the roll movement is to dampen it a little and prevent it when the fin is moved sideways.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-02-02T14:12:17.320" CommentCount="32" ContentLicense="CC BY-SA 3.0" />
  <row Id="24684" PostTypeId="2" ParentId="24679" CreationDate="2016-01-27T07:46:39.627" Score="17" Body="&lt;p&gt;Vortex generators are a kludge - a good design does not need them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are mostly added at later stages of the design process when some deficiencies need to be cured, but re-designing the aircraft is too expensive. They add a lot of drag, and do so &lt;strong&gt;always&lt;/strong&gt;, for the whole duration of a flight, when they are needed only in some corner of the flight envelope (say, when flying close to stall).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A clever way to install vortex generators can be found on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Short_Belfast&quot; rel=&quot;noreferrer&quot;&gt;Short Belfast&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FqnLX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FqnLX.jpg&quot; alt=&quot;Tail of the Short Belfast from below&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tail of the Short Belfast from below (own work). Note the vortex generators hidden in the hinge gap - they only move out into the airflow when they are needed: When the elevator is moved to large negative deflections.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-02-18T17:29:53.947" LastActivityDate="2019-02-18T17:29:53.947" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="24685" PostTypeId="2" ParentId="24676" CreationDate="2016-01-27T07:59:26.660" Score="11" Body="&lt;p&gt;As I am sure you are aware, the convention is that any aircraft that has the current US president on board is given the &quot;One&quot; call sign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For military aircraft, this is the branch of the military followed by &quot;One&quot;, which is why you have Air Force One, Marine One, Navy One. If he is on a civilian jet, it is called Executive One.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actual plane that everyone calls Air Force One is called VC-25, which is the military version of the 747.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been many planes that have been called Air Force One, from a King Air B90 to Gulfstream jets and even a combat aircraft like the S3 Viking (which was called Navy One).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, as far as I know - no president has flown in a C-130 while in office.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to close this off, if a president is no longer sitting and is transported; then the callsign changes to SAM (Special Air Mission); so for the &quot;Air Force One&quot; 747, this would be SAM 28000 or SAM 29000 - depending on which of the two is being used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The classified callsign for Air Force One is Angel.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="1049" LastEditDate="2016-01-27T08:06:01.767" LastActivityDate="2016-01-27T08:06:01.767" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24686" PostTypeId="1" AcceptedAnswerId="24687" CreationDate="2016-01-27T08:28:21.643" Score="14" ViewCount="2393" Body="&lt;p&gt;A previous question asked what the little metal plates between the horizontal and vertical stabilizer were (they are vortex generators), however I am much more interested in what the gray tube shaped structures are that go down the top quarter of the fuselage. What are they and what do they do? Are they sensors, countermeasure pods, something else?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="3386" LastEditDate="2019-09-20T03:21:15.153" LastActivityDate="2019-09-20T03:21:15.153" Title="What are the tube shaped structures on the back of the fuselage of this 737?" Tags="&lt;boeing-737&gt;&lt;feature-identification&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24687" PostTypeId="2" ParentId="24686" CreationDate="2016-01-27T10:12:22.500" Score="15" Body="&lt;p&gt;The aircraft is the Indonesian Airforce Boeing 737-2X9 “Surveiller” aircraft, used for Maritime Patrol. The fairings house Side looking Airborne Radar for matitime surveillance. From &lt;a href=&quot;http://www.b737.org.uk/737original.htm&quot;&gt;b737.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Fitted with Motorola AN/APS-135(V) Side Looking Airborne Modular Multi-Mission Radar (SLAMMR) The antenna of which was mounted in two 16ft housings on the upper rear fuselage. This system could spot small ships at ranges of 100nm. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Indonesia Operates three of them- AI-7301, AI-7302 and AI-7303. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-01-27T10:22:02.783" LastActivityDate="2016-01-27T10:22:02.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24688" PostTypeId="1" AcceptedAnswerId="24689" CreationDate="2016-01-27T11:02:19.107" Score="14" ViewCount="11501" Body="&lt;p&gt;In  &lt;a href=&quot;https://aviation.stackexchange.com/q/24686/4197&quot;&gt;this question&lt;/a&gt; the following image is shown, with the question what the two bulges at the aft fuselage are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I'm wondering what this wire is that starts somewhere midway the fuselage, and goes to the vertical stabilizer.&#xA;Is it also radar related?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LyfPd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hKt8W.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hKt8W.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.b737.org.uk/737original.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2020-10-04T18:28:27.713" Title="What is this wire going from mid-fuselage to the tail on this 737?" Tags="&lt;boeing-737&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24689" PostTypeId="2" ParentId="24688" CreationDate="2016-01-27T11:12:28.453" Score="13" Body="&lt;p&gt;It is the HF antenna. It was mostly used in older aircraft, which used them in trans-oceanic flights or in areas without UHF or VHF communications facilities.Modern 737s (and other aircraft in general) have done away with them. On later versions it was fitted in the leading edge of the Vertical fin of B737-200s, as shown in the figure below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TEMJ6.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TEMJ6.gif&quot; alt=&quot;B737 antenna&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from b737.org.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that these aircraft were delivered in 1982-83. Newer 737s don't have these.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-01-27T11:19:59.483" LastActivityDate="2016-01-27T11:19:59.483" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24693" PostTypeId="2" ParentId="24679" CreationDate="2016-01-27T13:48:38.893" Score="8" Body="&lt;p&gt;The vortex generators are used in commercial aircraft (Boeing especially), for a number of reasons, which are usually not applicable to GA aircraft. For example, vortex generators are used for anything from stall alleviation to &lt;a href=&quot;http://www.b737.org.uk/fuselage.htm#AFT_BODY_VORTEX_GENERATORS&quot; rel=&quot;noreferrer&quot;&gt;vibration reduction&lt;/a&gt; to noise reduction, some of which are not applicable for GA aircraft. Also, they are &lt;a href=&quot;http://www.smartcockpit.com/docs/Vortex_Generators.pdf&quot; rel=&quot;noreferrer&quot;&gt;usually added during testing&lt;/a&gt;, which is much more expansive compared to the GA aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, vortex generators are found in some aircraft, like the Piper Malibu Meridian, as shown below, &lt;a href=&quot;http://www.nasa.gov/centers/langley/news/factsheets/Micro-VG.html&quot; rel=&quot;noreferrer&quot;&gt;because of their advantages&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0KYaU.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0KYaU.gif&quot; alt=&quot;Micro VG&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from www.nasa.gov&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another point is the a &lt;a href=&quot;http://www.avweb.com/news/reviews/182564-1.html&quot; rel=&quot;noreferrer&quot;&gt;number of companies offer retrofit of VGs&lt;/a&gt; for GA aircraft. A number of GA aircraft have been retrofitted with them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zqGuV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zqGuV.jpg&quot; alt=&quot;VG retrofit&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Ahunt at English Wikipedia - I took this photo and release it to the public domain, Public Domain&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, they are quite costly and require extensive tests for certification, with the result that they are not used much compared to commercial aircraft. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-27T13:48:38.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24694" PostTypeId="1" CreationDate="2016-01-27T14:10:34.863" Score="4" ViewCount="764" Body="&lt;p&gt;This is a piece of &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Ilyushin_IL-2_Sturmovik,_Central_Air_Force_Museum,_Monino.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;this image from Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iSvkVm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iSvkVm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note the circled region. Movies often show exhaust fumes coming from those pipes when the engine is started. So I assume these are actual exhaust pipes.&#xA;This design doesn't appear very often, especially in modern piston engine airplanes. Why is this the case?&lt;/p&gt;&#xA;" OwnerUserId="2759" LastEditorUserId="2759" LastEditDate="2016-01-29T08:20:55.113" LastActivityDate="2016-01-29T08:20:55.113" Title="Why are the exhaust pipes design on the Ilyushin Il-2 not very popular?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;piston-engine&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24695" PostTypeId="2" ParentId="24694" CreationDate="2016-01-27T14:53:31.153" Score="5" Body="&lt;p&gt;This engine is about 10 times more powerful than a modern average piston engine. With such power you get some useful thrust from exhaust power directly. This design helps to recover it. With a small SEP, noise and keeping exhaust smoke away from the cabin probably is more important. And it's not true that it's not popular. It's popular with single engine turbines. &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/fc/QuestKodiakSunset.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/f/fc/QuestKodiakSunset.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: Wikimedia (click for link)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="5517" LastEditDate="2016-01-27T15:44:29.557" LastActivityDate="2016-01-27T15:44:29.557" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24696" PostTypeId="1" AcceptedAnswerId="24697" CreationDate="2016-01-27T15:05:07.970" Score="3" ViewCount="490" Body="&lt;p&gt;Given three very accurate laser gyros and accelerometers I believe the &lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;nofollow&quot;&gt;Inertial Reference System (IRS)&lt;/a&gt; should be as accurate in determining true altitude as it is in determining lat/long, providing the aerodrome elevation was supplied at initialization.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that pressure and density altitude are what is used in aviation, but could the IRS be used as a backup? Could it replace or backup a radar altimeter for approach/landing?&lt;/p&gt;&#xA;" OwnerUserId="1344" LastEditorUserId="1344" LastEditDate="2016-01-28T10:33:18.620" LastActivityDate="2016-01-28T10:33:18.620" Title="Why is the Inertial Reference System not used to determine true altitude?" Tags="&lt;altimeter&gt;&lt;gyroscopic-instruments&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24697" PostTypeId="2" ParentId="24696" CreationDate="2016-01-27T15:24:03.740" Score="9" Body="&lt;p&gt;IRS will drift over time. Decision altitude is 200ft for ILS CAT I approach.  0.5nm drift is not to much for navigation but it will be huge difference in altitude and you can hit obstacles if your altitude has drifted just couple of feet. Probably it could be used if backed by GPS as EGPWS does or non baro RNAV approaches do. But even GPS precision alone is not enough in this case and you need WAAS.&#xA;Radio altimeter can give much better precision.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-01-27T15:24:03.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24698" PostTypeId="2" ParentId="17178" CreationDate="2016-01-27T16:10:49.583" Score="10" Body="&lt;p&gt;As a retired USAF Navigator, I can tell you C-130's stopped using celestial Navigation by the mid-1990's.  As far as accuracy, if you were good at it, and that took years of practice, you could get within a couple of NM's, especially at night when you can use three stars.&lt;/p&gt;&#xA;" OwnerUserId="13216" LastActivityDate="2016-01-27T16:10:49.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24700" PostTypeId="1" AcceptedAnswerId="24701" CreationDate="2016-01-27T18:16:06.587" Score="31" ViewCount="3163" Body="&lt;p&gt;I was recently on a flight - the aircraft was a 737-800 - where I had a good view of the front of the left engine. The situation in the title did &lt;em&gt;not&lt;/em&gt; occur, but it seemed awfully close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After pushback, while the plane was waiting to start taxiing under its own power, I looked at the tiny waterspouts sporadically forming in front of the engine (it'd been raining all morning). And then I noticed a piece of caulk (or tar or whatever it is) was being lifted from between two concrete slabs of pavement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The strip of caulk looked like it might have been 30cm long and 2cm in &quot;diameter&quot; (it had a more rectangular cross-section, but you get the idea). It was still attached at one end, but it was directly in front of the engine, and its free end was being &quot;tugged&quot; up toward the intake in fits and starts, sometimes standing straight up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thankfully, it never went further than that. I considered alerting the cabin crew, but everyone was already buckled in, and I really didn't want to cry wolf on a airplane (so to speak). Still, I was very much considering it just as the plane started moving without any further drama.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As soon as we were in the air, I discreetly told a flight attendant, and she told the pilots. She came back a little later asking for a few specifics, so I imagine the pilots were radioing the airport we'd just left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I got a free cup of coffee (yay...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My question is:&lt;/strong&gt; What might have happened if that piece of debris had come loose and been ingested by the engine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wouldn't expect it to be catastrophic or anything (which is also why I hesitated in informing anyone while it was going on), but I would expect it to be &lt;em&gt;expensive&lt;/em&gt;. I.e. it might ground the plane, at least for a short while. Probably some flames out the back. &lt;em&gt;Maybe&lt;/em&gt; it'd even mess up the engine by gumming up the works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was never worried for my safety or anyone else's. I know engines are tough, and can eat all manner of crap. And even if they tear themselves apart in the process, they contain it. Not that I'd expect something like that happening at low power anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But really: I don't know for sure what would happen. I'm not a pilot or mechanic, just a nerd with a nerd's interest in engines and airplanes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit: Checking the airline's website, it seems the engine would be a CFM 56-7B26, if that's at all relevant.&lt;/p&gt;&#xA;" OwnerUserId="13218" LastEditorUserId="13218" LastEditDate="2016-01-28T18:37:59.047" LastActivityDate="2016-01-28T18:37:59.047" Title="What would have happened if the jet engine on my aircraft had ingested caulk from the pavement?" Tags="&lt;safety&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24701" PostTypeId="2" ParentId="24700" CreationDate="2016-01-27T20:08:01.713" Score="20" Body="&lt;p&gt;Well, not an expert on caulking, but birds go through plane engines sometimes, and they seem to be roughly the same consistency overall (if you account for the dirt and pebbles that are sometimes stuck to caulking.) So it possible they would have the same effect.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're curious about what would happen if it's like a birdstrike you can take a look at the &lt;a href=&quot;https://en.wikipedia.org/wiki/US_Airways_Flight_1549&quot;&gt;Miracle on the Hudson&lt;/a&gt;, or this 757 that had a &lt;a href=&quot;https://www.youtube.com/watch?v=L1jZvlFmqQU&quot;&gt;birdstrike on takeoff&lt;/a&gt;.  With the 757, they simply went around and landed the plane since they only lost one engine...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, you folks were still on the ground, so all that would have happened is that the engine would have flamed out while you were sitting there and the plane would need to be taken to service to check for damage.  It would have been annoying to have to switch planes, but it wouldn't have been dangerous to any of the passengers or crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nice of them to give you a free coffee though, considering you may have saved them a few hundred thousand in engine repairs if the next jet in that slot had managed to actually ingest the caulking ;).&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-01-27T21:08:27.513" LastActivityDate="2016-01-27T21:08:27.513" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24702" PostTypeId="1" CreationDate="2016-01-27T22:44:09.450" Score="4" ViewCount="185" Body="&lt;p&gt;Can the measured thrust of a propeller be greater than the maximum possible thrust predicted by &lt;a href=&quot;https://en.wikipedia.org/wiki/Momentum_theory&quot; rel=&quot;nofollow&quot;&gt;Froude's Propeller Theory&lt;/a&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is Froude's theory reliable in practice regarding the upper limit of the thrust delivered by a propeller of diameter, d, turned by an engine that absorbs the power, P?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I get the measured thrust of a 26 inch, 2 blades propeller, higher than what Froude's theory predicts.&lt;/p&gt;&#xA;" OwnerUserId="13223" LastActivityDate="2016-01-28T04:13:10.100" Title="Can the measured thrust of a propeller be greater than the max thrust predicted by Froude's theory?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24704" PostTypeId="2" ParentId="24702" CreationDate="2016-01-27T23:31:51.307" Score="2" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The actuator disc theory for &lt;a href=&quot;https://aviation.stackexchange.com/questions/14305/what-is-the-propeller-efficiency-%CE%BC-p-of-modern-propellers-for-light-sport-airc/15383#15383&quot;&gt;Propellers&lt;/a&gt; uses some simplifications, which are grouped into a propeller efficiency factor which normally is between 0.7 and 0.9. This accounts for friction and swirl losses, which are both neglected but very real. Also, the theory assumes equal speed over the stream tube and an infinitesimally small hub, both of which increases efficiency over that of real propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the propeller uses a large duct, Froude's actuator disc theory would be insufficient to explain all thrust. You might want to explain your measurements in more detail to get a better answer.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-01-28T02:13:55.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24706" PostTypeId="2" ParentId="24702" CreationDate="2016-01-27T23:50:37.253" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can the measured thrust of a propeller be greater than the maximum possible thrust predicted by Froude's Propeller Theory?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It might seem incredible but the answer looks to be: yes it can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;em&gt;Stoddard [1977] reports measured values of the thrust which exceed the theoretical upper limit as predicted by the momentum theory by 20% to 50%.&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://pure.tue.nl/ws/files/3577374/345682.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ON THE LIMITATIONS OF FROUDE'S&#xA;ACTUATOR DISC CONCEPT,&#xA;G.A.M. VAN KUIK. page 7.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Update&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;&lt;em&gt;For the propeller flow the momentum theory underestimates the induced velocity, while for the wind turbine flow this is overestimated. As the induced velocity has a different sign in both flow regimes, the total velocity at the disc $u_d = U_0 + u_i$ is underestimated in all flow states: the mass flow through the rotor is always higher than predicted by the classical momentum theory.&lt;/em&gt;&quot;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/qrLe1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qrLe1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: the same paper as above.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastEditorUserId="10018" LastEditDate="2016-01-28T04:13:10.100" LastActivityDate="2016-01-28T04:13:10.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24707" PostTypeId="1" AcceptedAnswerId="24709" CreationDate="2016-01-28T00:19:32.260" Score="19" ViewCount="3874" Body="&lt;p&gt;The other day I was spotting at Miami International (&lt;a href=&quot;https://en.wikipedia.org/wiki/Miami_International_Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;MIA/KMIA&lt;/a&gt;) and noticed something hanging out of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A man with a green jacket is holding a device attached to a cable. Can somebody determine what that is?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d52q3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d52q3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="5517" LastEditDate="2016-05-02T14:37:52.247" LastActivityDate="2016-05-02T14:37:52.247" Title="What is this string on the 737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24709" PostTypeId="2" ParentId="24707" CreationDate="2016-01-28T00:28:24.683" Score="24" Body="&lt;p&gt;The ground crew has connected a headset to the communication jack outsiede for flight pushback communication with the flight crew. from &lt;a href=&quot;http://www.b737.org.uk/communications.htm&quot; rel=&quot;noreferrer&quot;&gt;b737.org.uk&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The External Power Hatch is located beneath the F/O's DV window. It is used by groundcrew to connect the Ground Power Unit and headset for pushback communications with Flight Interphone.&lt;/p&gt;&#xA;&lt;p&gt;The service interphone is used by engineers to communicate with the service interphone stations inside the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Here is a closeup of the connection point&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/si3MX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/si3MX.jpg&quot; alt=&quot;Comm&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.b737.org.uk/communications.htm&quot; rel=&quot;noreferrer&quot;&gt;b737.org.uk&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;About &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=6&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwiNqrTSn8vKAhWDcY4KHWNVAK0QFggqMAU&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DB_NG-Communications.pdf&amp;amp;usg=AFQjCNE2cujG-G4lSlvpIYAagNEUBM0Y_A&amp;amp;bvm=bv.112766941,d.c2E&quot; rel=&quot;noreferrer&quot;&gt;flight interphone System&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The flight interphone system is an independent communication network. Its&#xA;primary purpose is to provide private communication between flight deck&#xA;crewmembers without intrusion from the service interphone system. The ground&#xA;crew may also use the flight interphone through a jack at the external power&#xA;receptacle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And here is a nose section of 737-200, showing it from a not so close angle.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bwqew.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bwqew.jpg&quot; alt=&quot;737-200&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from rigger.smugmug.com&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-28T23:25:20.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24710" PostTypeId="1" AcceptedAnswerId="37330" CreationDate="2016-01-28T00:45:46.937" Score="24" ViewCount="12004" Body="&lt;p&gt;Say a pilot plans to make a cross country flight along &lt;a href=&quot;https://en.wikipedia.org/wiki/Victor_airways&quot;&gt;Victor airways&lt;/a&gt;, but under VFR. Depending on workload and communication effectiveness along the way, our hero may provide the planned fairly complex route to the FAA at least three times.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Flight Service Station&lt;/li&gt;&#xA;&lt;li&gt;Tower, if departing from such an airport&lt;/li&gt;&#xA;&lt;li&gt;Approach/Departure Control or &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_Control_Center&quot;&gt;ARTCC&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;This seems like needless frequency congestion. Our hero happens across a &lt;a href=&quot;https://www.reddit.com/r/ATC/comments/3ysmn1/does_atc_see_my_flight_plan_while_setting_up/cyutjao&quot;&gt;suggestion&lt;/a&gt; from an ATC specialist that appears to solve the problem for everyone, emphasis in the original.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you file an IFR flight plan through any system, I will receive it. Make it clear to the first controller you contact that you want to fly your filed route as VFR and give the altitude. It is a very simple amendment I will be happy to make. The only difference on my flight strip is the altitude block that says &lt;code&gt;60&lt;/code&gt; for IFR or &lt;code&gt;VFR/65&lt;/code&gt; for VFR, and a &lt;code&gt;V&lt;/code&gt; in your data block on my radar scope. If you do this, do not accept an IFR clearance. If a controller says &lt;code&gt;cleared to&lt;/code&gt; any fix, that is an IFR clearance. Using this method, everything on my end will work smoothly whether you depart a towered or nontowered airport, and this would be the easiest method for the controllers involved. &lt;strong&gt;CAVEAT: I do not know if it is legal for a non-IFR rated pilot to file an IFR flight plan even if you don’t accept an IFR clearance.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;May a pilot lacking an instrument rating or currency legally do so?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-01-28T03:31:01.263" LastActivityDate="2018-02-13T15:41:18.737" Title="May a non-instrument pilot legally file IFR as long as he amends and doesn’t accept an instrument clearance?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;&lt;flight-plans&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24712" PostTypeId="1" AcceptedAnswerId="24785" CreationDate="2016-01-28T01:31:53.193" Score="4" ViewCount="1997" Body="&lt;p&gt;Why is horizontal stabilizer set to 4° up ( or any other setting other than neutral) in airbus aircraft for take off? Why can't we keep the trim neutral?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastActivityDate="2017-06-15T04:10:08.743" Title="Why is horizontal stabilizer set to 4° up in airbus aircraft for take off?" Tags="&lt;takeoff&gt;&lt;airbus&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24714" PostTypeId="1" AcceptedAnswerId="24734" CreationDate="2016-01-28T02:45:59.403" Score="7" ViewCount="1740" Body="&lt;p&gt;According to FAR 91.205(e) there must be DME or RNAV system when a pilot uses VOR navigation above FL240. However, why does the regulation say we need it from FL240, not from FL180 where class A begins?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="1467" LastEditDate="2016-01-28T14:24:08.390" LastActivityDate="2016-01-28T14:24:08.390" Title="Why do we need DME or RNAV when using VOR navigation above FL240?" Tags="&lt;faa-regulations&gt;&lt;vor&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24715" PostTypeId="1" CreationDate="2016-01-28T04:12:20.060" Score="10" ViewCount="4728" Body="&lt;p&gt;Supposing I'm a regional carrier and my routes never pass over water bodies (sea or lakes which are over a certain size). Am I obliged to carry life jackets on my plane?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="19" LastEditDate="2016-11-11T14:52:54.693" LastActivityDate="2017-04-12T07:45:01.213" Title="Are life jackets mandatory on planes that will never fly over water bodies?" Tags="&lt;regulations&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24716" PostTypeId="1" AcceptedAnswerId="24720" CreationDate="2016-01-28T05:17:18.757" Score="12" ViewCount="1641" Body="&lt;p&gt;Heads up: This came from Wikipedia's page on &lt;a href=&quot;https://en.wikipedia.org/wiki/Contra-rotating_propellers&quot;&gt;contra-rotating propellers&lt;/a&gt; and it explicitly says citation needed:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However they can be very noisy ... It is also helpful if the two propellers have a different number of blades (e.g. four blades on the forward propeller and five on the aft).&lt;sup&gt;[citation needed]&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Any truth to this? Can a variable number of blades per propeller really help reduce noise? If so, how?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(It doesn't explicitly say if it's piston prop or turbo prop. AFAIK, both can be used for contra-rotating props, and I have no idea which one would be more noisy, or if this supposed variable-blade idea will work on one but not the other.)&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="946" LastEditDate="2016-01-28T05:26:02.593" LastActivityDate="2017-09-29T13:49:34.813" Title="Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?" Tags="&lt;propeller&gt;&lt;noise&gt;&lt;noise-reduction&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24717" PostTypeId="1" AcceptedAnswerId="24718" CreationDate="2016-01-28T06:40:42.680" Score="5" ViewCount="2278" Body="&lt;p&gt;Is the APU a mini-jet engine, or some other type of motor? I know its purpose is to provide power when the engines are off, but what kind of motor/engine is used to generate the power?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume this differs from one type of aircraft to the other, but for the purposes of narrowing down the responses - I would like to know specifically about Boeing's APUs lets say on the 737NG.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-01-28T07:26:19.120" Title="What type of engine/motor is used in aircraft APU?" Tags="&lt;apu&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24718" PostTypeId="2" ParentId="24717" CreationDate="2016-01-28T07:20:57.833" Score="4" Body="&lt;p&gt;Since the only fuel available on an airliner is kerosene, the APU is a kerosene-powered jet. Using a different and maybe more efficient type of engine would require an independent fuel system, which does not make sense for the small savings possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.b737.org.uk/apu.htm&quot; rel=&quot;nofollow&quot;&gt;737.org&lt;/a&gt; page on APUs:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are many different APUs available for the 737. The most common&#xA;  is the Garrett GTCP (Gas Turbine Compressor [air] Power unit&#xA;  [electrics]) 85-129. This was standard for the series 1/200 but when&#xA;  the -300 was introduced it was found that two to three times the&#xA;  energy was needed to start the larger CFM56 engines. Garrett produced&#xA;  the 85-129[E] which had a stretched compressor, ie the impellers were&#xA;  lengthened and the tip diameters increased. When the 737-400 was&#xA;  introduced, even more output was required and Garrett produced the&#xA;  85-129[H]. This has an Electronic Temperature Control which limits hot&#xA;  section temperatures depending upon demand and ambient temperatures.&#xA;  By 1989 the 85-129[H] was the most standard APU in all 737 models,&#xA;  although there are actually 14 different models of the 85-129 in&#xA;  service with 737s.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To answer your question about the 737 NG, it continues:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Other APUs available are the Garrett GTCP 36-280(B) and the&#xA;  Sundstrand APS 2000 on the 3/4/500; and the &lt;a href=&quot;http://www.deltatechops.com/mro-capabilities/view/category/apu&quot; rel=&quot;nofollow&quot;&gt;Allied Signal GTCP 131-9B&lt;/a&gt;&#xA;  for the NGs. The main difference between them is that the Garrett is&#xA;  hydro-mechanical whereas Sundstrand and Allied Signal are FADEC&#xA;  controlled.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Be sure to load the &lt;a href=&quot;http://www.b737.org.uk/apu.htm&quot; rel=&quot;nofollow&quot;&gt;737.org page&lt;/a&gt;, it has lots of pictures and data on the APUs.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-28T07:26:19.120" LastActivityDate="2016-01-28T07:26:19.120" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24719" PostTypeId="1" CreationDate="2016-01-28T07:37:28.960" Score="1" ViewCount="120" Body="&lt;p&gt;In the VOR receiver we use two antenna, which are joined with the help of an assembly (part # CI 215), then the output of these two antenna is fed to RxR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is: how do we assure the serviceability of this unit (CI 215)?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Means coxial cable inner lead should short with outer OR Not.&lt;/li&gt;&#xA;&lt;li&gt;Both antenna Fitting point short with each other OR Not. &lt;/li&gt;&#xA;&lt;li&gt;coxial cable inner lead should short with both antenna Base fitting point OR Not.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="13226" LastEditorUserId="19" LastEditDate="2016-07-14T07:10:52.197" LastActivityDate="2016-07-14T07:10:52.197" Title="How is the serviceability of VOR unit part CI 215 checked?" Tags="&lt;vor&gt;" AnswerCount="0" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24720" PostTypeId="2" ParentId="24716" CreationDate="2016-01-28T07:41:28.370" Score="12" Body="&lt;p&gt;It does help a little, yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One source of noise is the fluctuation in dynamic pressure experienced by a blade of the rear propeller when it cuts through the wake of a blade of the forward propeller. Friction in the boundary layer on the first blade will reduce the dynamic pressure locally and create pressure fluctuations on the second blade, and noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By using a different number of blades, the pressure fluctuations will not happen all at the same time, but sequentially, which reduces the peak power of the noise. The effect of the second blade cutting through the wake of the first is still there, but is distributed over time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks to @MSalters for pointing out another effect. I copy straight from his comment:&#xA;The effect is not just distributed over time, but also shifted up in frequency. At 6000 RPM (100 Hz), with 4 blades per propeller they pass each other 8 times per revolution (800 Hz). If the second propeller has 5 blades, this moves up to 4000 Hz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/diYqW.jpg&quot; alt=&quot;An-70 with D-27 propfan&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://en.wikipedia.org/wiki/Progress_D-27&quot; rel=&quot;noreferrer&quot;&gt;P-27 prop on the D-27 turboshaft of the An-70 transport&lt;/a&gt;, picture by Marina Lystseva. The forward propeller has 8 blades and the rear propeller has 6. For optimum noise reduction, the rear propeller should have just one blade less than the forward propeller. The leading edge sweep helps to stretch out the contact of a single blade with the wake over time, which again reduces peak noise.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-01-28T08:29:49.757" LastActivityDate="2016-01-28T08:29:49.757" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24721" PostTypeId="1" AcceptedAnswerId="24732" CreationDate="2016-01-28T08:04:56.720" Score="7" ViewCount="981" Body="&lt;p&gt;I already validated my non-US licence and got a FAA Private VFR SE Licence based on my foreign licence. I recently completed my IFR rating in my home country and was wondering how to 'upgrade' my FAA licence and add the IFR privileges?!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried my best to find something on google but I only found references to a &quot;FAA Instrument Knowledge Test Foreign Pilots&quot; without any details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any experience or pointers for me?&lt;/p&gt;&#xA;" OwnerUserId="1957" LastEditorUserId="1467" LastEditDate="2016-04-28T11:33:49.193" LastActivityDate="2016-08-13T00:08:48.240" Title="I have a FAA Private VFR SE license based on my foreign license, and added IFR in my home country; how to upgrade the FAA license?" Tags="&lt;instrument-flight-rules&gt;&lt;faa&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24722" PostTypeId="1" AcceptedAnswerId="24724" CreationDate="2016-01-28T08:27:05.800" Score="3" ViewCount="1072" Body="&lt;p&gt;Right about now (Jan 28, 2016, 08:12 UTC), a Boeing 737-8AS is cruising over Manitoba/Nunavut on a delivery flight from Seattle Boeing Field (BFI) to Dublin Airport (DUB). The flight is labelled RYR800F, and is clearly a delivery flight for the European low-cost airline Ryanair.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NuS1K.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NuS1K.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have always wondered who flies the plane in such situations. I would appreciate if you could give me a few insights into how these events are managed by the manufacturer and the Company. I envision the following cases, but which one of them, or combination of them, is true?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The plane is flown by a special pilot unit of the buying Company, which flies to the manufacturer's logistic airport, checks for conformity, signs a few documents, and then flies the plane to the Company's headquarters or hub;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) The plane is flown by a special pilot unit of the manufacturer. They fly the plane to the Company's headquarters or hub, then meet the buyer to check for conformity and sign the documents. Eventually, the pilot unit flies back to manufacturer's base as regular passengers onboard other flights;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) The plane is flown by two units: one belongs to the manufacturer and the other to the buyer. They check for conformity, sign the documents, and jointly fly the plane, in order for the manufacturer and the buyer to share immediate feedback on the plane's performance while airborne;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) The plane is flown by a contracted pilot unit, which performs the duty as a third party payed by the buyer or by both the buyer and the manufacturer. This unit also includes a member of the buyer. They reach the manufacturer's base, the buyer's employee signs the documents, and then the plane is flown to the Company's headquarters or hub.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume each Company has its own policy in this regard, but which one of these procedures do you think is the most common? Thanks!&lt;/p&gt;&#xA;" OwnerUserId="11885" LastEditorUserId="1467" LastEditDate="2016-01-28T08:43:25.310" LastActivityDate="2016-01-28T10:06:04.847" Title="Who pilots an aircraft that is on a delivery flight?" Tags="&lt;commercial-aviation&gt;&lt;ferry-flight&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2016-01-28T13:08:35.610" ContentLicense="CC BY-SA 3.0" />
  <row Id="24723" PostTypeId="1" AcceptedAnswerId="25037" CreationDate="2016-01-28T08:48:17.403" Score="6" ViewCount="205" Body="&lt;p&gt;Are checklists normally written in English? If pilots are native speakers in another language, is it possible/legal for them to use the translated version of the checklist?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This may be different for the small private aircraft and commercial airliner. Please cover multiple cases when possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Soviet Union pilots probably used Russian for checklist. However I ask about open, developed countries (Germany, France, etc) and planes that are used all over the world.&lt;/p&gt;&#xA;" OwnerUserId="917" LastActivityDate="2016-02-08T08:29:13.147" Title="Are checklists always written in English?" Tags="&lt;checklist&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24724" PostTypeId="2" ParentId="24722" CreationDate="2016-01-28T10:06:04.847" Score="10" Body="&lt;p&gt;Typically the customer will travel to the manufacturers location for a final inspection and acceptance of the new aircraft. This includes one or several test flights with staff of both the manufacturer and the customer on board, thorough systems checking and final modifications if necessary. The acceptance of the aircraft is then made official by signing off a pack of papers. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then the customer transfers the final sum of money to the manufacturer and the aircraft is signed over to the customer. The delivery flight is typically operated solely by the customer's staff, however if it is the first aircraft of the specific type for the customer, the manufacturer may send training staff along for final training of the ground staff at the customers location if agreed so. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2016-01-28T10:06:04.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24726" PostTypeId="1" AcceptedAnswerId="24728" CreationDate="2016-01-28T11:40:39.970" Score="12" ViewCount="19829" Body="&lt;p&gt;What's the difference (for the purpose) between &lt;strong&gt;positioning&lt;/strong&gt; and &lt;strong&gt;ferry&lt;/strong&gt; flight?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="1696" LastEditDate="2016-01-28T18:21:39.657" LastActivityDate="2020-03-27T18:39:56.510" Title="What is the difference between a positioning flight and a ferry flight?" Tags="&lt;flight-planning&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24727" PostTypeId="2" ParentId="24712" CreationDate="2016-01-28T12:08:17.460" Score="1" Body="&lt;p&gt;The idea is to trim the airplane for the initial climb phase, so it assumes the correct attitude and speed without further control input. The exact value depends on CG location, weight, flap setting, temperature and more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider you take off in IMC with nose-down trim and get the least bit distracted. The aircraft is at a &lt;a href=&quot;https://en.wikipedia.org/wiki/KLM_Flight_633&quot; rel=&quot;nofollow&quot;&gt;real risk to hit the ground&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-01-28T12:08:17.460" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24728" PostTypeId="2" ParentId="24726" CreationDate="2016-01-28T12:08:58.593" Score="15" Body="&lt;p&gt;A &lt;strong&gt;positioning&lt;/strong&gt; flight is a flight for the sole purpose of positioning the aircraft to conduct another flight from another airport. This is often done when the aircraft finishes its day in one city, but is needed in a different city the following day because another plane has broken down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A positioning flight is technically a type of &lt;strong&gt;ferry&lt;/strong&gt; flight, however the latter is a more broad term. Examples of ferry flights include delivery from the manufacturer, or flying to a different city for heavy maintenance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both flights are generally conducted without fare-paying passengers on board, but sometimes extra airline staff are carried. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-01-28T12:08:58.593" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24729" PostTypeId="2" ParentId="24726" CreationDate="2016-01-28T12:14:06.843" Score="4" Body="&lt;p&gt;Ferry flight refers to flying the aircraft from the factory or flying of the aircraft to or from major maintenance (overhaul).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Positioning flight refers to the aircraft to some place(airport) from which it is operated. For example, an aircraft may be positioned at an airport for normal operations from the next day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both are non revenue flights. They are often used interchangeably. NTSB, however, seems to consider ferry flights as a type of positioning flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Eurocontrol defines &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/article/attachments/eurocontrol-glossary-for-flight-statistics-and-forecasts.pdf&quot; rel=&quot;nofollow&quot;&gt;positioning flight&lt;/a&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A non-revenue flight carried out to position an aircraft for a scheduled or non-scheduled flight or service. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-01-28T12:31:35.323" LastActivityDate="2016-01-28T12:31:35.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24730" PostTypeId="1" CreationDate="2016-01-28T12:51:02.417" Score="10" ViewCount="1354" Body="&lt;p&gt;Does existing Avionics / Control Systems on large Commercial Jets make use of differential thrust of engines much? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. I was contemplating applications of this sort: Normally the thrust provided by each of multiple jet engines will be different due to difference in age, wear, build etc. and this is usually compensated by rudder trim.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But instead, would it be feasible for a controller to detect the slight yaw moment and modulate the throttle setting to compensate thereby negating the use of rudder trim?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about a more general strategy in which the use of rudder trim, or more extremely rudder itself is reduced via automated differential thrust modulation of jet engines? i.e. Using differential thrust not just yaw compensation but yaw creation as well? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do such systems already exist? Or is there a fundamental flaw in my reasoning that make these ideas not viable? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-06-27T07:59:39.053" LastActivityDate="2019-11-15T16:39:01.103" Title="Do existing large commecial jets make use of differential thrust to control yaw?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24731" PostTypeId="2" ParentId="24726" CreationDate="2016-01-28T13:24:11.607" Score="2" Body="&lt;p&gt;There's no absolute accepted definition across the world, however generally it depends on whether passengers could be carried on the flight. In a positioning flight the airplane could carry passengers, in a ferry flight usually not due to the condition of the airplane (mechanical problems, extra fuel tanks) or the ownership. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-01-28T13:24:11.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24732" PostTypeId="2" ParentId="24721" CreationDate="2016-01-28T13:30:54.033" Score="5" Body="&lt;p&gt;I assume that your FAA private license was issued under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_175&quot;&gt;14 CFR 61.75&lt;/a&gt;, and that section also includes the requirements for adding instrument privileges:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) &lt;em&gt;Instrument ratings issued&lt;/em&gt;. A person who holds an instrument rating&#xA;  on the foreign pilot license issued by a contracting State to the&#xA;  Convention on International Civil Aviation may be issued an instrument&#xA;  rating on a U.S. pilot certificate provided:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The person's foreign pilot license authorizes instrument&#xA;  privileges;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Within 24 months preceding the month in which the person applies&#xA;  for the instrument rating, the person passes the appropriate knowledge&#xA;  test; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The person is able to read, speak, write, and understand the&#xA;  English language. If the applicant is unable to meet one of these&#xA;  requirements due to medical reasons, then the Administrator may place&#xA;  such operating limitations on that applicant's pilot certificate as&#xA;  are necessary for the safe operation of the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &quot;appropriate knowledge test&quot; in this case is the &lt;em&gt;Instrument Rating - Foreign Pilot&lt;/em&gt; test, it's described &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_guides/media/faa-g-8082-13i.pdf&quot;&gt;here&lt;/a&gt; with a few sample questions. Some more information is &lt;a href=&quot;http://www.faa.gov/training_testing/testing/media/testing_matrix.pdf&quot;&gt;here&lt;/a&gt;, including the point that you don't need any prior authorization to take the test:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;• Requires NO instructor endorsement or other form of written&#xA;  authorization.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure about the exact process involved (I guess you just do the test and send the certificate to the FAA) but the FSDO that validated your foreign license for VFR should be able to give you all the details.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-01-28T13:30:54.033" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24733" PostTypeId="1" AcceptedAnswerId="44495" CreationDate="2016-01-28T13:39:03.663" Score="10" ViewCount="705" Body="&lt;p&gt;I found this image of a medal figuring Concorde and a globe with two contours of continents, before and after Concorde, expressing the new speed of air transport with a motto &quot;May Concorde bring people closer.&quot; (&quot;Que Concorde rapproche les hommes&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As I find this material extremely relevant to express the global geography of time-space during the supersonic period, to I would like to know more about it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Where does this medal and motto come from?&lt;/li&gt;&#xA;&lt;li&gt;Was it present onboard?&lt;/li&gt;&#xA;&lt;li&gt;Was it used in other forms of communication?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/y0qeb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/y0qeb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12955" LastEditorUserId="12955" LastEditDate="2016-01-29T08:48:04.657" LastActivityDate="2018-05-28T12:55:03.997" Title="What is the history of Concorde motto &quot;May Concorde bring people closer&quot; and medal?" Tags="&lt;aviation-history&gt;&lt;concorde&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24734" PostTypeId="2" ParentId="24714" CreationDate="2016-01-28T14:00:55.940" Score="1" Body="&lt;p&gt;The &lt;a href=&quot;https://www.google.com/webhp?sourceid=chrome-instant&amp;amp;ion=1&amp;amp;espv=2&amp;amp;ie=UTF-8#q=why%20do%20we%20need%20dme%20above%20fl240%5C&quot; rel=&quot;nofollow&quot;&gt;consensus of internet wisdom&lt;/a&gt; seems to be that no one knows for sure, but the most likely explanation is that before class A existed there was Positive Control Airspace (PCA) that started at FL240, and DME was a requirement in PCA. The main reasons for requiring DME were:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There's a limited number of &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range#Service_volumes&quot; rel=&quot;nofollow&quot;&gt;high-altitude VORs&lt;/a&gt; so it isn't easy to use cross-radials from other VORs for fixes or position reporting; DME is a simple alternative&lt;/li&gt;&#xA;&lt;li&gt;If there's no radar coverage then ATC can still manage lateral separation effectively using DME&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That all seems plausible enough, but some sources out there say that PCA started at FL180, not FL240, e.g. this &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/artcc/chicago/information/media/BriefHistory.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA history document&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[VFR on top] was a principle [sic] factor in the &lt;a href=&quot;https://en.wikipedia.org/wiki/1956_Grand_Canyon_mid-air_collision&quot; rel=&quot;nofollow&quot;&gt;[Grand Canyon] crash&lt;/a&gt; and led to&#xA;  &quot;Positive Control Airspace&quot; (PCA) FL180 and above. Because of the&#xA;  speeds of the aircraft involved, non-radar procedures were unwieldy&#xA;  (standards called for ten minutes between aircraft; some 80 miles for&#xA;  a typical jet), even with the development of aircraft installed&#xA;  Distance Measuring Equipment (DME) and the reduced separation&#xA;  available between DME equipped aircraft (20 miles).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;FL240 is also where ATC starts using Mach numbers instead of knots (ATC orders &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;section 5-7-1(f)&lt;/a&gt;) and the separation minima change (section 8-4-4). I don't know if that's for historical reasons or physical/operational reasons, but it looks to me like FL240 is considered the general starting point for high-altitude operations (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_131&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.31&lt;/a&gt; requires a high-altitude endorsement for aircraft that can operate above 25,000' MSL).&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-01-28T14:00:55.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24735" PostTypeId="2" ParentId="24694" CreationDate="2016-01-28T14:25:04.797" Score="5" Body="&lt;p&gt;It was popular at that time. All the &lt;a href=&quot;https://en.wikipedia.org/wiki/Curtiss_P-40_Warhawk&quot; rel=&quot;nofollow&quot;&gt;Curtiss P-40 Warhawk&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_P-51_Mustang&quot; rel=&quot;nofollow&quot;&gt;North American P-51 Mustang&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Hurricane&quot; rel=&quot;nofollow&quot;&gt;Hawker Hurricane&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Supermarine_Spitfire&quot; rel=&quot;nofollow&quot;&gt;Supermarine Spitfire&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Hawker_Tempest&quot; rel=&quot;nofollow&quot;&gt;Hawker Tempest&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Bf_109&quot; rel=&quot;nofollow&quot;&gt;Messerschmitt Bf109&lt;/a&gt; and many more had similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That kind of exhaust was tied to the engine, a water-cooled 2-line 12-cylinder &lt;a href=&quot;https://en.wikipedia.org/wiki/V12_engine#Later_V12s_in_aviation&quot; rel=&quot;nofollow&quot;&gt;(V-12)&lt;/a&gt; and later some 4-line 24-cylinder (&lt;a href=&quot;https://en.wikipedia.org/wiki/H_engine#Aircraft_engines&quot; rel=&quot;nofollow&quot;&gt;H-24&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/X_engine&quot; rel=&quot;nofollow&quot;&gt;X-24&lt;/a&gt;) engines. So there was a row of cylinders on each side and each had its own exhaust pipe as short as possible to minimize its resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since then, anything with more than 6 cylinders was replaced by turbines and all the smaller engines are air-cooled, because in GA aircraft the simplicity of air-cooled engine is more useful than the slightly lower drag of water-cooled one (navy preferred air-cooled even in fighters for the same reason). And air-cooled engines generally have their exhaust pipes lead into the cooling air stream and thus hidden under the cowling.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-01-28T22:44:06.557" LastActivityDate="2016-01-28T22:44:06.557" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="24736" PostTypeId="2" ParentId="24712" CreationDate="2016-01-28T14:37:24.550" Score="2" Body="&lt;p&gt;Both landing and take-off are critical phases of flight, and it is standard procedure to configure the aircraft for those phases to reduce the workload on the crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On landing, aircraft are configured for a &lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/35/376/Stabilized%20Approach%20Concept.pdf&quot; rel=&quot;nofollow&quot;&gt;stabilized approach&lt;/a&gt;, which means that the aircraft can be flown to the runway with a minimum of configuration changes to flaps/slats, trim, power, and drag devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On take-off, the aircraft is configured for take-off, and trim is set so as to provide a slight nose-up. If the trim is set nose low, it requires a lot of pull to &quot;unstick&quot; the aircraft from the runway. If the trim is set too nose high, then the aircraft will want to nose up before the aircraft may be ready to fly, and then to continue a nose-up attitude after rotation, requiring more than a minimal effort to keep the a proper departure attitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nose-up trim can induce what is called a &lt;em&gt;trim stall&lt;/em&gt;, which is when the trim is set so far back that the aircraft will exceed the critical angle on take-off:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ELEVATOR TRIM STALL&#xA;  The elevator trim stall maneuver shows what can happen&#xA;  when full power is applied for a go-around and&#xA;  positive control of the airplane is not maintained.&#xA;  [Figure 4-8] Such a situation may occur during a&#xA;  go-around procedure from a normal landing approach&#xA;  or a simulated forced landing approach, or&#xA;  immediately after a takeoff. The objective of the&#xA;  demonstration is to show the importance of making&#xA;  smooth power applications, overcoming strong trim&#xA;  forces and maintaining positive control of the airplane&#xA;  to hold safe flight attitudes, and using proper and&#xA;  timely trim techniques.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Source: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-3of7.pdf&quot; rel=&quot;nofollow&quot;&gt;Airplane Flying Handbook&lt;/a&gt; p. 4-10&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-01-28T14:37:24.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24737" PostTypeId="1" CreationDate="2016-01-28T16:25:22.660" Score="2" ViewCount="314" Body="&lt;p&gt;The crew is facing a situation, in which, the altimeters indicate different altitude (the port and starboard ones - cpt´s and FO´s). Is there any procedure to perform an IFR landing?&#xA;If we consider a light aircraft, what the crew will do?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="62" LastEditDate="2016-01-28T16:45:47.330" LastActivityDate="2016-01-28T16:45:47.330" Title="Altimeter disagreement. What's the crew procedure to deal with that?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;flight-instruments&gt;&lt;altimeter&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24738" PostTypeId="2" ParentId="24737" CreationDate="2016-01-28T16:31:52.630" Score="3" Body="&lt;p&gt;Since you describe a captain and FO, I'm going to assume that you are asking about a larger aircraft, like say an airliner or business jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Part of the certification of these types of aircraft require them to have a third (standby) altimeter in addition to the two primary altimeters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When there is a discrepancy, the typical procedure (keep in mind that a pilot should always follow the manufacturers checklist in these situations) is to cross-check the three altimeters and find the two that agree so that the bad one is then excluded.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-01-28T16:31:52.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24739" PostTypeId="1" CreationDate="2016-01-28T16:33:28.847" Score="8" ViewCount="2649" Body="&lt;p&gt;When the crew receives &quot;airspeed disagree&quot; message on the primary flight displays, they may face some hazardous situation.&#xA;Is there any procedure, using a table containing pitch, power, altitude and weight, to avoid stall, for example?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="167" LastEditDate="2016-01-29T14:21:56.423" LastActivityDate="2016-01-29T14:21:56.423" Title="What is the correct crew procedure for an unreliable airspeed alert?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;flight-instruments&gt;&lt;airspeed&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24740" PostTypeId="2" ParentId="14389" CreationDate="2016-01-28T17:44:27.320" Score="0" Body="&lt;p&gt;That is a yes. They are proposing to move away from the NAS FP (FAA Form 7233-1) and require use of the FAA Form 7233-4 (The FAA version of an international flight plan).   The move is hoped for the fall of 2016. The delay was to get all vendors up to speed, and iron out procedures for specialty flight plans like those for the DC SFRA and DVFR etc.&lt;/p&gt;&#xA;" OwnerUserId="13236" LastActivityDate="2016-01-28T17:44:27.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24741" PostTypeId="1" AcceptedAnswerId="24744" CreationDate="2016-01-28T17:49:11.743" Score="3" ViewCount="1023" Body="&lt;p&gt;I have seen that some aircraft have some of their windows painted white. As you can see in this picture, this A340 has many windows painted white. &#xA;Why is it that?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BQo2g.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BQo2g.jpg&quot; alt=&quot;thai a340&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Thai-Airways-International/Airbus-A340-642/2080482/&amp;amp;sid=649d71173d559aba90e35ec42dcf070a&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T18:04:29.357" LastActivityDate="2016-03-05T18:04:29.357" Title="Why are some aircraft windows painted over?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-01-28T19:08:39.797" ContentLicense="CC BY-SA 3.0" />
  <row Id="24742" PostTypeId="2" ParentId="24741" CreationDate="2016-01-28T17:51:30.717" Score="1" Body="&lt;p&gt;It means that there is some sort of internal structuer (like a wall or a cooking unit) behind that window on that particular configuration of the aircraft.  Manufacturers are required to certify the planes with windows in place in order to show that they don't suffer from metal fatigue after repeated flights.  So moving a window (or covering it up with metal) is a lot harder than just putting a little plastic cover on the inside of the window.  Hence, when a particular configuration places a wall or a cooking unit there, they just cover it up.&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2016-01-28T17:51:30.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24743" PostTypeId="2" ParentId="22903" CreationDate="2016-01-28T18:17:38.193" Score="11" Body="&lt;p&gt;In the context of fuel, jettisoning fuel would imply that the fuel is in a container that can be detached while in flight. In the linked image, the large tank below the main body is an external fuel pod that can be &lt;em&gt;jettisoned&lt;/em&gt;. &lt;a href=&quot;http://www.elbitsystems.com/elbitmain/pic/Cyclone_F-18_Parts_[570x370].jpg&quot; rel=&quot;noreferrer&quot;&gt;Jet with external fuel tank&lt;/a&gt; I believe in WWII that P51s would have &lt;a href=&quot;https://en.wikipedia.org/wiki/Drop_tank&quot; rel=&quot;noreferrer&quot;&gt;drop tanks&lt;/a&gt; for escorts that would be jettisoned once an enemy encounter was expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dumping fuel would simply mean that there is a type of valve located on the fuel tanks that can be actuated in some way such that the fuel can freely exit. &lt;a href=&quot;https://www.metabunk.org/sk/20141001-084459-y7bka.jpg&quot; rel=&quot;noreferrer&quot;&gt;Jetliner dumping fuel&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To say differently, if one was holding water in a bucket, pouring the water on the ground would be 'dumping fuel' and simply dropping the bucket would be 'jettisoning fuel'&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reviewing the wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_dumping&quot; rel=&quot;noreferrer&quot;&gt;Fuel Dumping&lt;/a&gt;, the author(s) make no such distinction between &lt;code&gt;dumping&lt;/code&gt; vs &lt;code&gt;jettisoning&lt;/code&gt; and seem to use &lt;code&gt;jettison&lt;/code&gt; solely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the context of ATP, after reading the wikipedia article on fuel dumping, I believe that they are considered synonyms. I believe a non-pilot would go more along with my definition however. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I answered in this manner as I believe that the OP is not a native English speaker and that clarification was needed as to distinguishing the two as they seem very similar. I am a native English speaker, but lay no claim to being a master of it.&lt;/p&gt;&#xA;" OwnerUserId="12483" LastActivityDate="2016-01-28T18:17:38.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24744" PostTypeId="2" ParentId="24741" CreationDate="2016-01-28T18:31:13.977" Score="6" Body="&lt;p&gt;If you look at the &lt;a href=&quot;http://www.seatguru.com/airlines/Thai_Airways/Thai_Airways_Airbus_A340-600.php&quot;&gt;seating chart for that plane&lt;/a&gt;, you'll notice that those windows match the location of toilets and galleys.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the exact position of toilets and galleys may change during the lifetime of an aircraft, so it's easier to have all the windows installed by design, and just obstruct some that are not used. Even if it were just obstructed from within, I suppose it's better if in an emergency, if emergency personnel had to look inside the plane (to check for people still trapped inside), they would be able to identify quickly those windows that do not need looking through.&lt;/p&gt;&#xA;" OwnerUserId="3313" LastActivityDate="2016-01-28T18:31:13.977" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24745" PostTypeId="2" ParentId="24739" CreationDate="2016-01-28T19:05:04.743" Score="12" Body="&lt;p&gt;As you probably know this is the situation that occurred for &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;AF-447 (Rio-Paris)&lt;/a&gt; on June 2009. From the &lt;a href=&quot;https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf&quot; rel=&quot;noreferrer&quot;&gt;BEA report&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The accident resulted from the following succession of events:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Temporary inconsistency between the measured airspeeds, likely following the obstruction of the Pitot probes by ice crystals that led&#xA;in particular to autopilot disconnection and a reconfiguration to&#xA;alternate law, [...]&lt;/li&gt;&#xA;&lt;li&gt;The crew not making the connection between the loss of indicated airspeeds and the appropriate procedure,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This mistake happened previously. From the same report:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Four crews did not identify the unreliable airspeed  situation: in two&#xA;cases, the crews concluded that there was an inconsistency between the&#xA;angles of attack; in the two other cases, the crew considered that the&#xA;speeds were erroneous rather than unreliable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Then the procedure that should be used in case of unreliable airspeed:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The philosophy for processing the anomaly is described in the&#xA;“UNRELIABLE AIRSPEED INDICATION / ADR CHECK PROCEDURE” that is in&#xA;Flight Manual (AFM) and transcribed in the Airbus FCOM and the Air&#xA;France Operations Manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FsZQE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FsZQE.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;This procedure which is to be known without the support of the documentation gives time to retrieve data from the documentation (this is what you wanted to know):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/05GJD.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/05GJD.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;See also:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Unreliable_Airspeed_Indications&quot; rel=&quot;noreferrer&quot;&gt;Unreliable Airspeed Indications&lt;/a&gt; on SKYbrary.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-28T19:34:10.983" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24746" PostTypeId="2" ParentId="3428" CreationDate="2016-01-28T19:58:06.213" Score="-2" Body="&lt;p&gt;&lt;strong&gt;Closed systems (Box Wing is only a particular type of closed wing), C-wings and biwings are actually related as far as the minimization of induced drag is concerned.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested in technical answers regarding the &lt;strong&gt;induced drag minimization/performance of Box Wings, closed systems, bi-wing systems, and multiwings&lt;/strong&gt;, you can find all the details in the following publications (I can also send to you the papers if you email me at the address &lt;em&gt;luciano.demasiATgmail.com&lt;/em&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;=====Article 1 =====&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Demasi Luciano, Monegato  Giovanni, Dipace  Antonio and Cavallaro  Rauno &quot;&lt;strong&gt;Minimum Induced Drag Theorems for Joined Wings, Closed Systems, and Generic Biwings: Theory&lt;/strong&gt;&quot;, Journal of Optimization Theory and Applications, 2015, pages 1-36, DOI: 10.1007/s10957-015-0849-y, ISSN:0022-3239&lt;/p&gt;&#xA;&#xA;&lt;p&gt;=====Article 2 =====&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Demasi  Luciano, Monegato  Giovanni, Rizzo  Emanuele, Cavallaro  Rauno and Dipace  Antonio &quot;&lt;strong&gt;Minimum Induced Drag Theorems for Joined Wings, Closed Systems, and Generic Biwings: Applications&lt;/strong&gt;&quot; Journal of Optimization Theory and Applications, 2015, Pages 1-25,Doi: 10.1007/s10957-015-0849-y, ISSN:0022-3239&lt;/p&gt;&#xA;&#xA;&lt;p&gt;=====Article 3 =====&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Demasi  Luciano, Monegato  Giovanni, Cavallaro  Rauno &quot;&lt;strong&gt;Minimum Induced Drag Theorems for Multi-Wing Systems&lt;/strong&gt;&quot; ,2016,4-8 January,SciTech2016, San Diego, California, AIAA 2016-0236&lt;/p&gt;&#xA;&#xA;&lt;p&gt;=====Article 4 =====&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Demasi  Luciano, Dipace  Antonio, Monegato  Giovanni, Cavallaro  Rauno &#xA;&quot;&lt;strong&gt;Invariant Formulation for the Minimum Induced Drag Conditions of Nonplanar Wing Systems&lt;/strong&gt;&quot;, AIAA Journal, 2014,October,10,2223-2240,52, Doi:10.2514/1.J052837&#xA;  Url: &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/1.J052837&quot; rel=&quot;nofollow&quot;&gt;http://arc.aiaa.org/doi/abs/10.2514/1.J052837&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sincerely,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luciano Demasi&lt;/p&gt;&#xA;" OwnerUserId="13239" LastActivityDate="2016-01-28T19:58:06.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24747" PostTypeId="2" ParentId="24730" CreationDate="2016-01-28T21:15:38.687" Score="14" Body="&lt;p&gt;No, differential thrust is used in normal operations only when maneuvering on the ground, and then manually, not driven by a computerized control system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is preferable to run all engines at the same speed. Not only would you add additional frequencies, but also the beat frequency between pairs of two engines if speeds differ. This makes it harder to check with your ear that all engines are humming away nicely and generally creates more noise than when the engines run in sync. The answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/14263/what-is-propeller-engine-sync-and-how-does-it-work/14266#14266&quot;&gt;this question&lt;/a&gt; explain what the beat frequency is and how synchronization is achieved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, the lag in engine response makes the control loop prone to oscillations. A rudder command is executed quickly and precisely, and when the deflections are below maybe 10°, no profile drag penalty is incurred. Induced drag due to lateral trim should be very small, especially at high speed. Trim deflections are normally much below that value, so an efficiency benefit from trimming with differential engine speeds is unlikely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During take-off and initial climb both engines run at maximum thrust, and any trim requirement would reduce total thrust. This reduction is small, but sometimes every bit counts. During descent, the opposite happens and one engine might need to run at a higher thrust level than ideal. To decouple lateral trim and control from thrust makes sense in those cases.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-29T10:20:15.967" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24748" PostTypeId="1" AcceptedAnswerId="24749" CreationDate="2016-01-28T23:05:28.690" Score="18" ViewCount="6222" Body="&lt;p&gt;There is a hole on the belly fairing circled in yellow. I guess is an air intake but I tried searching some info and couldn't find anything. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/2wWao.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2wWao.jpg&quot; alt=&quot;Atr 75&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Lufthansa-Regional-(Contact/ATR-ATR-72-500-(ATR-72-212A)/2770341/&amp;amp;sid=1d596faa40fcdaf8ab77a0568c5fe208&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="3386" LastEditDate="2018-08-07T01:35:47.157" LastActivityDate="2018-08-07T01:35:47.157" Title="What's this hole on the ATR-72?" Tags="&lt;feature-identification&gt;&lt;atr-72&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24749" PostTypeId="2" ParentId="24748" CreationDate="2016-01-29T00:01:53.473" Score="24" Body="&lt;p&gt;It is the ram air intake for the air conditioning system. There are two of them, one on each side.&lt;/p&gt;&#xA;&lt;p&gt;Here is an image from the &lt;a href=&quot;http://www.737ng.co.uk/atr72fcom.pdf&quot; rel=&quot;noreferrer&quot;&gt;ATR-72 FCOM&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZqhJp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZqhJp.jpg&quot; alt=&quot;ATR 72&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;ATR-72 Air conditioning System, image from 737ng.co.uk&lt;/p&gt;&#xA;&lt;p&gt;Details from the same document:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The air conditioning system is supplied by air processed through two packs which regulate air flow and temperature. The two packs are installed in the main landing gear fairings and operate automatically and independently.&lt;/p&gt;&#xA;&lt;p&gt;The left pack supplies the cabin and cockpit air conditioned; the right pack supplies only the cabin air conditioned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also, as @Jonathan Walters points out, the intake is a good example of NACA inlet (or NACA scoop) and are found in a number of aircraft, for example &lt;a href=&quot;https://aviation.stackexchange.com/questions/16566/what-exactly-is-this-opening-in-the-belly-of-a-boeing-737/16577&quot;&gt;Boeing 737&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-29T00:26:43.007" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24750" PostTypeId="1" AcceptedAnswerId="24751" CreationDate="2016-01-29T02:30:29.397" Score="6" ViewCount="1136" Body="&lt;p&gt;I'm not talking about errors or omissions. Does a FP ever get rejected for example if there are too many flights scheduled into an airport or it conflicts with other flights or your FP as filed would take you through an active TFR area? How much scrutiny does a FP get when it's filed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/q/14091/8730&quot;&gt;this question&lt;/a&gt; I see that VFR plans get pretty much just filed away in case you need S&amp;amp;R. Does someone at ATC go through and verify that an IFR plan doesn't have conflicts?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-01-29T14:17:55.160" Title="Do IFR flight plans ever get rejected for operational reasons?" Tags="&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;flight-plans&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24751" PostTypeId="2" ParentId="24750" CreationDate="2016-01-29T03:08:23.357" Score="6" Body="&lt;p&gt;Generally speaking, the only reasons for which a flight plan would be actually &lt;em&gt;rejected&lt;/em&gt; would fall under what you referred to as &quot;errors or omissions&quot;. But, the operational reasons you cite might lead to an amendment to your flight plan (which the pilot would most likely receive as an amended clearance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFR flight plans filed electronically are rejected by the flight plan processing computer if the filer files an impossible flight plan. I would presume that a flight plan filed verbally or in person through ATC or FSS would also be rejected for the same reasons, probably by the same computer, but with the rejection relayed to you through the third party. See these rejection examples that AOPA lays out in &lt;a href=&quot;http://flighttraining.aopa.org/students/crosscountry/articles/4779.html&quot;&gt;this article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you plan a &quot;direct&quot; flight, point-to-point, follow the rules and&#xA;  enter the correct equipment. For example, if &quot;/G&quot; (or &quot;slash Golf,&quot;&#xA;  meaning that your airplane is equipped with an IFR-approved GPS and a&#xA;  Mode C transponder) or &quot;/I&quot; (you have loran or VOR/DME and a Mode C&#xA;  transponder) are not entered for these kinds of flights, the air&#xA;  traffic control computer will reject your flight plan because that&#xA;  route can't be flown with less capable equipment.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;File fixes that are actually on&#xA;  the airways that you file in your IFR flight plan. Pilot error causes&#xA;  flight plans to be rejected when the filed points are not on the&#xA;  routes that are filed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Depending on how you file, other possible rejection reasons might include formatting errors, a non-existent clearance limit, or might depend on the specific filing means; I am certainly not familiar with all means of filing. I have filed in person with a sheet of paper when standing in the office at the bottom of a control tower, over the phone, and online, and over the aircraft radio; I've never had an IFR flight plan actually rejected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond such reasons, a flight plan will typically not be &lt;em&gt;rejected&lt;/em&gt; as such, but may well be amended. The reasons you propose—traffic density, route issues, etc—are usually negotiable, or are circumvented by amendments to your clearance. Certainly, these issues may present challenges, but they can usually be worked around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These flight plans do receive scrutiny; IFR clearances are all about traffic separation, and this is ATC's primary task. Understand that to file an IFR flight plan is, essentially, to apply for a specific routing for specific time frame; you may or may not be given your requested routing when you receive your actual clearance. Receiving a clearance different from the route filed, or receiving a clearance amendment while en-route are both common. Note that an amendment need not be ATC initiated: the pilot can request an amendment, either before or during a flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One final note on TFRs: you can sometimes (often?) fly through these, even under VFR; you just have to get approval. For example, I've flown through the Grand Forks TFR while flying VFR with ATC approval.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-01-29T03:15:40.230" LastActivityDate="2016-01-29T03:15:40.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24752" PostTypeId="1" CreationDate="2016-01-29T06:07:19.430" Score="23" ViewCount="3337" Body="&lt;p&gt;I searched for an infamous golf ball question on this site but did not find any, so I guess it's time for one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would a dimpled surface like a golf ball somehow improve the aerodynamics of an airplane? (there are many planes for many purposes, so let's just go with my favorite: large commerical passenger planes, Mach 0.85 cruise, several hundred tons loaded weight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They actually tried this for a car on &lt;a href=&quot;https://www.youtube.com/watch?v=eR5SlwNf4K0&quot;&gt;myth busters&lt;/a&gt; and they claimed an 11% improvement in miles-per-gallon, so you can't say the question has no merit. Unfortunately, they did not try it for an airplane.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2016-01-29T08:41:31.870" LastActivityDate="2016-01-31T10:56:50.070" Title="Is a golf ball surface a good idea for wings or fuselage?" Tags="&lt;aerodynamics&gt;&lt;efficiency&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24754" PostTypeId="1" CreationDate="2016-01-29T08:44:25.437" Score="2" ViewCount="400" Body="&lt;p&gt;The air gaspers (in large passenger aircraft) above the passengers' heads are fed from the main air conditioning system, at least in all aircraft that I am familiar with (see also &lt;a href=&quot;https://aviation.stackexchange.com/a/12357/1478&quot;&gt;this answer&lt;/a&gt;). This design probably makes sense, as it's very simple (no moving parts other than the gaspers) and takes advantage of a system which is already installed in the aircraft to provide additional functionality. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still, I'm curious: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;have other designs for individually adjustable passenger ventilation been tried (i.e. installed in large passenger aircraft), and why were they abandoned in favour of the current design? Off the top of my head I can think of a system with little fans above each seat - although it's probably far more prone to breaking than the current system. &lt;/li&gt;&#xA;&lt;li&gt;Some cars have individual climate control (where the air supplied to each occupant can have a different temperature), has that ever been tried on a large commercial aircraft? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="8282" LastEditDate="2017-11-07T17:41:58.857" LastActivityDate="2017-11-07T17:41:58.857" Title="Have other designs for individual gasper ventilation been tried?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24755" PostTypeId="2" ParentId="24752" CreationDate="2016-01-29T12:18:04.853" Score="18" Body="&lt;p&gt;Golf ball has dimples on its surface because we want a turbulent boundary layer. Golf ball is a bluff body (i.e. the drag is dominated by pressure drag). Hence, the drag on a sphere is dominated by the separation on the rear face. If we could minimize that, the drag would be reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following figure shows the variation of drag coeffecient of a sphere with Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uYdUS.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uYdUS.gif&quot; alt=&quot;drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from wfis.uni.lodz.pl, taken from (Hoerner 1965)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen, the drag reduces at the critical Reynolds number, which is the point where separation takes place. Because of separation, the wake in the rear of the sphere (or ball) is reduced, which reduces drag. So, if the boundary layer of a sphere can be made turbulent at a lower Reynolds number (by some means), then the drag should also go down at that Reynolds number, as a result of the reduced wake. This can be seen in the following picture, where the flow has been made turbulent using a trip wire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bXCdj.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bXCdj.gif&quot; alt=&quot;turbulent&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow over a sphere: (a) Reynolds number = 15,000; (b) Reynolds number = 30,000, with trip wire. Image from princeton.edu&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is the purpose of having dimples in a golf ball- to reduce drag by inducing turbulence and delaying separation (this can be achieved by increasing the Reynolds number; but we are limited by the ball speed). The resulting wake is much smaller due to the delayed separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of a streamlined shape (like aircraft wing), the propotion of pressure drag is small, as can be seen below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F3jI8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F3jI8.jpg&quot; alt=&quot;Drag prop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from pilotfriend.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of streamlined shapes, the pressure drag is small because the wake is small. The net result is that 'tripping' the boundary layer as in bluff bodies is not a good idea (a laminar flow causes less friction drag than a turbulent one). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircrafts do use similiar devices, via the &lt;a href=&quot;https://aviation.stackexchange.com/questions/13876/what-is-a-vortex-generator&quot;&gt;vortex generator&lt;/a&gt;, which are used mainly to delay flow separation.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-01-31T10:56:50.070" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24756" PostTypeId="1" CreationDate="2016-01-29T12:34:33.440" Score="14" ViewCount="5549" Body="&lt;p&gt;The title really asks it all: &lt;strong&gt;When can a pilot disobey ATC commands?&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the pilot has the final decision, but when would the pilot really disobey someone in ATC with much more knowledge of planes and other potential hazards near by?&lt;/p&gt;&#xA;" OwnerUserId="11428" LastEditorUserId="11428" LastEditDate="2016-01-29T19:07:00.517" LastActivityDate="2016-01-29T19:07:00.517" Title="When can a pilot disobey ATC commands?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ClosedDate="2016-01-29T22:42:57.397" ContentLicense="CC BY-SA 3.0" />
  <row Id="24757" PostTypeId="2" ParentId="24756" CreationDate="2016-01-29T13:13:54.693" Score="14" Body="&lt;p&gt;A pilot can break any rule in the book for the safety of the flight or those on the ground. Ultimately the safety of the flight rests with the pilot in command of the aircraft and therefore not just the right but the duty to diverge from ATC instructions if the situation warrants. Examples of this might be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A cabin depressurization or engine failure requiring an immediate descent&lt;/li&gt;&#xA;&lt;li&gt;A change in course or altitude to avoid a collision with an aircraft or terrain&lt;/li&gt;&#xA;&lt;li&gt;Passenger illness&lt;/li&gt;&#xA;&lt;li&gt;Unlawful interference&lt;/li&gt;&#xA;&lt;li&gt;When intercepted by law enforcement or the military&lt;/li&gt;&#xA;&lt;li&gt;If complying with an instruction is hazardous, for instance putting the aircraft outside its flight envelope, into a possible collision&lt;/li&gt;&#xA;&lt;li&gt;Fuel emergencies&lt;/li&gt;&#xA;&lt;li&gt;Mechanical problems&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In cases such as these pilots will take immediate action and inform ATC afterwards if they can.  &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-01-29T13:13:54.693" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24758" PostTypeId="2" ParentId="24756" CreationDate="2016-01-29T13:19:29.063" Score="19" Body="&lt;p&gt;In case of emergencies, yes. The pilot in command has the final authority and responsibility for safety of the flight and can disobey ATC commands in case of emergencies. The reasons for that and the results will decide the consequences.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.123&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §91.123 Compliance with ATC clearances and instructions&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) When an ATC clearance has been obtained, no pilot in command may deviate from that clearance &lt;strong&gt;unless an amended clearance is obtained, an emergency exists&lt;/strong&gt;, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory.&lt;/p&gt;&#xA;&lt;p&gt;(b) &lt;strong&gt;Except in an emergency&lt;/strong&gt;, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=7b2be47d0f0b0f80a9b50b8f55ebb950&amp;amp;r=SECTION&amp;amp;n=14y3.0.1.1.7.20.3.20&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §121.557   Emergencies: Domestic and flag operations&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) In an emergency situation that requires immediate decision and action the &lt;strong&gt;pilot in command may take any action&lt;/strong&gt; that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter, to the extent required in the interests of safety.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Emphasis mine. Obviously, it would be prudent for the the pilot (and required under FAR 91.123(c), as @Pondlife points out) to report the deviation to the ATC as soon as possible.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-29T13:42:20.863" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24759" PostTypeId="2" ParentId="24752" CreationDate="2016-01-29T13:34:47.370" Score="12" Body="&lt;p&gt;Yes, the question has merit!&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It depends on the size and speed of the airplane. An airliner is too large and flies too fast to benefit from a dimpled surface. Dimpling the surface would actually increase drag. But some &quot;dimpling&quot; helps at the scale of model aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Explanation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;It all comes down to the flow condition at the point where &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=36%7C0.1082#5055&quot;&gt;flow separation&lt;/a&gt; occurs. In calm air, every boundary layer starts as a laminar boundary layer. Since the energy transfer across the stratified flow in the laminar boundary layer is reduced to shear, the molecules close to the wall will lose speed quickly, so that even at a modest pressure rise downstream separation occurs quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the laminar boundary layer, small disturbances become less and less damped the higher the &lt;a href=&quot;https://aviation.stackexchange.com/questions/21712/global-versus-local-reynolds-number/21741#21741&quot;&gt;local Reynolds number&lt;/a&gt; becomes, and at a &lt;a href=&quot;https://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds number&lt;/a&gt; of around 400,000 in unaccelerated flow some frequencies become unstable (see &lt;a href=&quot;https://en.wikipedia.org/wiki/Tollmien%E2%80%93Schlichting_wave&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tollmien-Schlichting waves&lt;/a&gt;) and will eventually create so much cross movement that the boundary layer becomes turbulent. Now parcels of air which flow at high speed in the outer part of the boundary layer will move close to the wall and kick the slow parcels there ahead, greatly reducing the deceleration of the flow close to the wall, at the price of slowing down and expanding the whole boundary layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a turbulent boundary layer is much better in following a contour with an adverse pressure gradient since it shows less deceleration of the flow at the wall. A pressure rise is generally caused by a contracting body shape. Separation is delayed and the separation, once it occurs, is much smaller. The pressure in separated flow is lower than ambient, so rearward-facing areas with separated flow cause massive drag. Therefore, separation needs to be suppressed as long as possible to minimize drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the contour of a body contracts at a local Reynolds number below that where natural transition to a turbulent boundary layer occurs, the still laminar boundary layer will cause early separation. The dimples of a golf ball help to trip the boundary layer early into its turbulent version, thus delaying separation and reducing drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the local Reynolds number (which is proportional to the product of speed and body length) is higher, such that the boundary layer turns turbulent before the part of the body with the adverse pressure gradient is reached, dimpling the surface will still cause earlier transition, but will not change the separation location. Even worse, it will reduce the area of laminar flow, and the increased area with a turbulent boundary layer will cause &lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956#16956&quot;&gt;more friction drag&lt;/a&gt;. The pressure fluctuations along a dimpled surface will weaken the boundary layer, and the dimpled airplane will show earlier and more separation compared to a smooth version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dimpling the whole surface is not necessary if the local direction of flow is known. A golf ball needs to have dimples all around so that at least some end up where they can help to trip the boundary layer, but on a wing only a small strip needs such a tripping device, called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbulator&quot; rel=&quot;nofollow noreferrer&quot;&gt;turbulator&lt;/a&gt;. Some model aircraft and gliders already use them to achieve less separation, but here small dimples are less effective than a zig-zag tape. How it works merits a question of its own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gM2xu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gM2xu.jpg&quot; alt=&quot;Spool of zig-zag tape&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spool of zig-zag tape (picture &lt;a href=&quot;http://wingsandwheels.com/media/wysiwyg/Zig_Zag_Turbulator_Tape.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-01-30T23:51:32.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24760" PostTypeId="2" ParentId="24750" CreationDate="2016-01-29T14:12:16.413" Score="3" Body="&lt;p&gt;In busy airspaces like Europe and US east coast, checking for congestion is done. This does not mean directly comparing the specific routes and waypoints—conflicts on that scale are easily resolved by assigning different altitudes—but number of aircraft that are expected to fly through each sector, or land at each airport, at every hour. And only certain number is permitted so the controllers assigned to the sector can handle it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But as far as I know the Network Manager Operations Centre (formerly Central Flow Management Unit; that does this in Europe) does &lt;em&gt;not reject&lt;/em&gt; the flight plans, but it &lt;em&gt;delays&lt;/em&gt; them. You file a flight plan and they'll give you expected release time. And if the destination or some sector along the route are congested, this might be several hours in the future. And then it's up to you whether you accept the wait or try to file a different plan that avoids the congested airspace. In airlines the dispatcher does this depending on how the extra fuel needed for longer route compares to the disruption caused by the delay.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-01-29T14:17:55.160" LastActivityDate="2016-01-29T14:17:55.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24761" PostTypeId="2" ParentId="24756" CreationDate="2016-01-29T14:13:07.237" Score="8" Body="&lt;p&gt;Others have talked about emergencies, which allows a pilot to take any action he sees fit. This is correct, and you could even argue that it's not really disobeying, as in the moment the emergency was declared, all clearances sort of went out the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's one important part missing and that's the option for a pilot to &lt;em&gt;not&lt;/em&gt; accept a clearance or an amendment. A clearance is not an instruction as much as it's a negotiation, and once established, is more or less valid until both pilot and controller can agree on something different. If they can't agree, by either the pilot saying &quot;unable&quot; for whatever reason, or in the case where radio communication is lost and the pilot didn't actually hear anything, he is expected to carry on as previously cleared.&lt;/p&gt;&#xA;" OwnerUserId="2" LastActivityDate="2016-01-29T14:13:07.237" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24762" PostTypeId="2" ParentId="24754" CreationDate="2016-01-29T14:58:28.217" Score="6" Body="&lt;p&gt;Whether or not they have been &quot;tried&quot; is probably not answerable, as &quot;try this&quot; type designs typically don't make it into production aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at the simplicity of the existing system, its simply some lightweight ducting with an adjustable air vent above each seat. The entire system has no other electric or adjustable parts, so maintenance is pretty easy, as well as reliability. Its also probably a hell of a lot easier to get certified. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting little fans above each seat wouldn't have any benefit here, as the air they move from one side of the fan to the other side has to be of a significant volume anyway, so you would still need ducting. The fan speed would be controllable, but then again so is the orifice size of the existing vents, so really no benefit there other than complexity and more wiring/electronics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The existing system also works relatively well for individual climate control. Unlike in your car, you don't have a large space between you and the person next to you, so getting &quot;individual&quot; control is difficult (Seat A at X degrees, Seat B at Y degrees, etc). But note that even in your car you really aren't adjusting the heat or cold temperature, but the fan speed either through the AC system or through the heater. The heater and AC are at a constant temperature all the time.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-01-29T14:58:28.217" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24763" PostTypeId="1" AcceptedAnswerId="24777" CreationDate="2016-01-29T16:10:52.597" Score="17" ViewCount="6131" Body="&lt;p&gt;I've noticed that the wings on the A380 are very curved in comparison to the 747. I mean the 747 has a lot of wing flex but the A380 has less wing flex and the wings are flexed down in comparison to the 747. Here there are two photos that might help you understand what I'm writing. So why are the A380 wings like that and what are the benefits?&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Emirates/Airbus-A380-861/2719120/&amp;amp;sid=11b3cb3b23b13b442fb7282ae2059e82&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/GOdk8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GOdk8.jpg&quot; alt=&quot;a380&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CDkyQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CDkyQ.jpg&quot; alt=&quot;7478&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mileagegenius.com/?p=4948&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-02-18T04:09:33.917" LastActivityDate="2019-02-18T16:29:57.883" Title="Why was the A380 built with a gull-wing design?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;airbus-a380&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24764" PostTypeId="2" ParentId="24756" CreationDate="2016-01-29T16:13:00.457" Score="11" Body="&lt;p&gt;To add one more case to what's been mentioned, if ATC tells you to climb to avoid a conflict and TCAS tells you to descend, pilots are required to follow the TCAS command rather than ATC's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason behind this is that TCAS in the two aircraft can typically coordinate &quot;behind the scenes&quot; which aircraft will do what in order to avoid a collision, but there's no guarantee that both aircraft are hearing the same plan from ATC. Maybe separate controllers both issue a &quot;climb&quot; command, or one aircraft is on the wrong frequency, or whatever. But the TCAS-to-TCAS communication is sufficiently reliable that this is now a required (although extremely rare) case of disobeying ATC.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-01-29T16:13:00.457" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24765" PostTypeId="1" AcceptedAnswerId="24766" CreationDate="2016-01-29T18:42:13.037" Score="9" ViewCount="2009" Body="&lt;p&gt;A triplane, mainly used in WW1 on the german side, was a biplane with 3 wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What were the advantages to having more wings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, why don't countries use them today?&lt;/p&gt;&#xA;" OwnerUserId="13253" LastEditorUserId="13197" LastEditDate="2016-01-29T23:36:44.423" LastActivityDate="2016-01-31T22:09:10.190" Title="What advantages and disadvantages do tri planes have?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24766" PostTypeId="2" ParentId="24765" CreationDate="2016-01-29T18:59:50.577" Score="1" Body="&lt;p&gt;Narrower wing chords versus a biplane of similar span and area.&#xA;More efficient and increased lift&#xA;Potentially faster rate of climb, tighter turning radius&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just to name a few.  You're essentially increasing the surface area without increasing the wingspan&lt;/p&gt;&#xA;" OwnerUserId="9567" LastActivityDate="2016-01-29T18:59:50.577" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24767" PostTypeId="1" AcceptedAnswerId="24768" CreationDate="2016-01-29T19:05:15.427" Score="1" ViewCount="18428" Body="&lt;p&gt;What types of antennae do aircraft have and what are their functions? Examples are HF-, VOR- and SATCOM-Antennae.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorDisplayName="user12485" LastEditDate="2016-01-29T23:14:37.003" LastActivityDate="2016-01-29T23:14:37.003" Title="What types of antennae do aircraft have and what are their functions?" Tags="&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2016-01-29T23:17:35.640" ContentLicense="CC BY-SA 3.0" />
  <row Id="24768" PostTypeId="2" ParentId="24767" CreationDate="2016-01-29T19:42:53.907" Score="2" Body="&lt;p&gt;Like everything in aviation this depends on how the plane is configured and what equipment it contains. This question is pretty broad and there are even some non aviation related antennae on modern commercial planes for things like onboard internet but lets cover the aviation related ones. &lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/special/antenna.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AOPA provides a great document on it here&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any plane equipped with GPS will have a GPS unit somewhere on the airframe (usually on the top)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3Qnhg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Qnhg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://i.ebayimg.com/00/s/MTA2NlgxNjAw/z/XGUAAOSwpdpVb3sf/$_35.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are generally 2 radio antennas for the communication radios. Traditionally one is mounted on the top of the plane and the other on the bottom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On smaller GA planes they generally look like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dbCJt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dbCJt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.cyclenetparts.com/images/items2/c16/SAM_3652_b8470d.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your plane is equipped with VOR receiving capability you will have a VOR antenna as well which is generally mounted on the tail. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3KB80.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3KB80.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.flyingstart.ca/FlightTraining/preflight/vorantenna2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also have a UHF antenna for your transponder and DME, its located on the bottom of the plane &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/munfR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/munfR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/special/antenna.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If equipped with an ELT you will also have an ELT antenna, generally on top. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dCagB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dCagB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://flighttraining.aopa.org/students/presolo/special/antenna.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It should be noted this is the general setup of most smaller GA planes. Large commercial planes have the same general equipment but often have greater redundancy and/or more units than your typical GA plane. Some airframes also have antennas for systems that are being phased out like Loran based navigation (which I think has been all but shut down now).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-01-29T20:28:15.003" LastActivityDate="2016-01-29T20:28:15.003" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24769" PostTypeId="2" ParentId="24763" CreationDate="2016-01-29T19:48:58.983" Score="2" Body="&lt;p&gt;The A380 has a gull-wing design. This has some economic benefits, the main one being shorter landing gear while giving enough ground clearance for the engines.&lt;/p&gt;&#xA;" OwnerUserId="11268" LastEditorUserId="1961" LastEditDate="2017-09-26T21:46:37.293" LastActivityDate="2017-09-26T21:46:37.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24771" PostTypeId="2" ParentId="24767" CreationDate="2016-01-29T21:15:31.760" Score="4" Body="&lt;p&gt;The Boeing 787 has just about every kind of antenna I can think of. Here's a chart of all their locations and purposes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/me4UV.jpg&quot; alt=&quot;787 antenna chart&quot;&gt;&#xA;From Boeing 787 Systems Manual&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-01-29T21:15:31.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24772" PostTypeId="1" CreationDate="2016-01-29T21:31:24.070" Score="15" ViewCount="905" Body="&lt;p&gt;In a C172P, the manoeuvring speed is 99 KIAS at 2400 lbs, 92 KIAS at 2000 lbs, and 82 KIAS at 1600 lbs. However, it is 102 KIAS at 2100 lbs when in the utility category, which has a more restrictive aft C of G limit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why the increase in $V_a$? My guess is that not allowing such an aft C of G in utility category allows the higher manoeuvring speed because this also restricts how low the stall speed could get. Is this correct?&lt;/p&gt;&#xA;" OwnerDisplayName="user13148" LastEditorDisplayName="user13148" LastEditDate="2016-01-29T22:02:34.870" LastActivityDate="2016-02-02T15:01:15.157" Title="Why is manoeuvring speed higher in utility category?" Tags="&lt;aircraft-performance&gt;&lt;stall&gt;&lt;weight-and-balance&gt;&lt;aircraft-limitations&gt;&lt;v-speeds&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24773" PostTypeId="1" CreationDate="2016-01-29T22:19:39.890" Score="23" ViewCount="4994" Body="&lt;p&gt;Reading &lt;a href=&quot;https://aviation.stackexchange.com/questions/3844/why-turn-off-pitot-tube-heating&quot;&gt;Why turn off pitot tube heating?&lt;/a&gt;, it appears that the pitot tube heat can be switched off to extent its lifetime and also in case of short-circuit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/phy7U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/phy7U.jpg&quot; alt=&quot;Thales pitot-static probe&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Thales pitot-static probe, source BEA)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On airliners the probes seem to be heated during the whole flight. This makes me ask myself different but related questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Accidents occurred due to probes freezing. How can a heated pitot probe freeze?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Extending the life of the tube seems a questionable choice, I'd rather expect the technology to be improved and be able to sustain permanent heat. &lt;strike&gt;Heating a small metal device from -56°C to 5°C (&lt;em&gt;or maybe more, say 100°C, taking into account comments&lt;/em&gt;) looks like feasible (not taking into account air friction)&lt;/strike&gt; ⇢ The problem seems to be how to transfer enough heat from the metal (which is very hot) to the ice accretion.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A short-circuit is easily terminated by a fuse or a circuit breaker. Why does the crew have to worry about switching the heat manually, adding a possibility to have it OFF unintentionally?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2019-02-03T21:15:02.540" Title="How can a pitot tube freeze when it's heated?" Tags="&lt;safety&gt;&lt;pitot-static&gt;&lt;af447-accident&gt;&lt;aircraft-subsystem&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24775" PostTypeId="2" ParentId="24710" CreationDate="2016-01-29T23:20:33.233" Score="13" Body="&lt;p&gt;I am not aware of, and have not been able to find any regulation governing the &lt;em&gt;filing&lt;/em&gt; of flight plans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only applicable rule that I know of in the FAR's is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=02adf9c0c460b391cd452f18b03273bd&amp;amp;node=se14.2.61_13&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.3&lt;/a&gt;(e), which says that no pilot may &lt;strong&gt;act&lt;/strong&gt; as PIC under IFR (which you would not be doing in the situation that you describe above):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) &lt;em&gt;Instrument rating.&lt;/em&gt; &lt;strong&gt;No person may act as pilot in command&lt;/strong&gt; of a&#xA;  civil aircraft &lt;strong&gt;under IFR&lt;/strong&gt; or in weather conditions less than the&#xA;  minimums prescribed for VFR flight &lt;strong&gt;unless that person holds&lt;/strong&gt;:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The appropriate aircraft category, class, type (if required), &lt;strong&gt;and&#xA;  instrument rating&lt;/strong&gt; on that person's pilot certificate for any airplane,&#xA;  helicopter, or powered-lift being flown;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) An airline transport pilot certificate with the appropriate&#xA;  aircraft category, class, and type rating (if required) for the&#xA;  aircraft being flown;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) For a glider, a pilot certificate with a glider category rating&#xA;  and an airplane instrument rating; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) For an airship, a commercial pilot certificate with a&#xA;  lighter-than-air category rating and airship class rating.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I do remember my instructor having me file IFR flight plans when I was working on my instrument rating (with them as the PIC), and for that matter many airlines and flight planning services often file flight plans on behalf of a pilot.  I doubt that all of them have instrument ratings (many aren't even pilots) yet it happens all of the time and I can't find any examples of violations.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As @mongo provides in his answer, the FAA has issued an LOI on this matter, and while my answer stands as far as the legality of having non-certificated people file flight plans, they feel that it would be against the rules to list a non-qualified pilot as the PIC.  Therefore, if you are filing on behalf of someone else who is qualified, all should be well, but don't do it if the PIC is not instrument rated.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2017-06-19T18:12:09.747" LastActivityDate="2017-06-19T18:12:09.747" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24776" PostTypeId="1" AcceptedAnswerId="24780" CreationDate="2016-01-29T23:21:32.333" Score="7" ViewCount="1504" Body="&lt;p&gt;The other day I made a question about the External Power Hatch. Now I would want to know what's that hole below the door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dlasd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dlasd.jpg&quot; alt=&quot;737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="14897" LastEditDate="2017-12-31T10:04:13.960" LastActivityDate="2017-12-31T10:04:13.960" Title="What is this device below the door of a 737 (and other aircraft)?" Tags="&lt;aircraft-systems&gt;&lt;feature-identification&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24777" PostTypeId="2" ParentId="24763" CreationDate="2016-01-30T00:08:15.693" Score="20" Body="&lt;p&gt;The wings are designed like that. You can see them in the picture below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ulRgw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ulRgw.jpg&quot; alt=&quot;A380&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airliners.net&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The A380 wings are designed to be the most efficient while still inside the 80m 'box' for efficient airport operations. The result is a clean slate design which used CFD extensively to get the most efficient aerodynamic design possible.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 'curve' near the root means that the landing gear in the wings could be as short as possible while being long enough to prevent a tail strike during rotation and allowing the spar to pass below the floor.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The shape also allows enough ground clearance for the inboard engines. This assumes importance with the advent of engines with ever higher bypass ratios.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Of course, the use of modern composite materials means the the wing 'flexes' up to be more or less straight once the aircraft is airborne.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hzyuS.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hzyuS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Air-to-air_shot_of_an_Emirates_Airbus_A380.jpeg&quot; rel=&quot;noreferrer&quot;&gt;wikimedia.org&lt;/a&gt;) In-flight 'flex'.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-02-17T04:30:34.710" LastActivityDate="2019-02-17T04:30:34.710" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24778" PostTypeId="1" AcceptedAnswerId="24786" CreationDate="2016-01-30T00:10:26.050" Score="14" ViewCount="27300" Body="&lt;p&gt;I understand that Cat I, II, and III ILS approaches have progressively smaller weather minimums. However, I am asking about the aircraft themselves. What are the differences between Cat levels as concerns aircraft equipment requirements and approvals?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="12720" LastEditDate="2016-01-30T00:35:01.707" LastActivityDate="2016-01-30T18:07:59.893" Title="What are the differences between Cat I, Cat II, and Cat III as concerns aircraft requirements?" Tags="&lt;ils&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24779" PostTypeId="2" ParentId="24776" CreationDate="2016-01-30T01:14:31.407" Score="-1" Body="&lt;p&gt;Looks like the potable water supply point. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IUWeF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IUWeF.jpg&quot; alt=&quot;B737-700&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from 737 Airport planning document&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-30T01:14:31.407" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24780" PostTypeId="2" ParentId="24776" CreationDate="2016-01-30T01:42:07.987" Score="11" Body="&lt;p&gt;That is the &lt;a href=&quot;http://www.b737.org.uk/pressurisation.htm#Pressurisation_Valves&quot; rel=&quot;nofollow noreferrer&quot;&gt;outflow valve&lt;/a&gt;. The outflow valve allows air to leave the pressurized section of the fuselage. The aircraft's pressurization system controls the valve to keep the desired pressure, balancing the air coming in through the &lt;a href=&quot;https://aviation.stackexchange.com/q/16796/1696&quot;&gt;bleed system&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C3cZb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C3cZb.jpg&quot; alt=&quot;Outflow valve closeup&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;&lt;a href=&quot;http://www.b737.org.uk/pressurisation.htm#Pressurisation_Valves&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-01-30T01:42:07.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24781" PostTypeId="2" ParentId="24773" CreationDate="2016-01-30T03:24:33.393" Score="22" Body="&lt;p&gt;Captain Bill Palmer, in his book &quot;&lt;a href=&quot;http://www.barnesandnoble.com/mobile/w/understanding-air-france-447-bill-palmer/1115883136&quot; rel=&quot;noreferrer&quot;&gt;Understanding Air France 447&lt;/a&gt;&quot; has a section dedicated to answering that very question as it pertains to AF447. Although there is no way to know for certain he puts forward some possibilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He quotes a commenter on a website: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One commenter on the Weather Graphics website’s AF447 article provided this interesting observation: “I'm an aircraft icing specialist and wanted to point out a factor that hasn't been discussed much … high ice crystal concentrations. I've seen flight test data from power rollbacks due to flight in high ice crystal environments … In our case, the crystals collected within heated, aspirated Ram Air Temperature sensors, forming a 0 ° C slush…”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;He notes that just before the pilot tubes clogged, the sound of ice crystals hitting the windshield could be heard on the CVR.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ice crystals bounce off the exterior of an airplane and cause no visible ice accretion, but they can enter the probe inlets. When highly specific climatic conditions exist in combination with certain combinations of altitude, temperature, and Mach, the concentration of ice crystals entering a probe can exceed its capacity to melt and evacuate the moisture through its drain holes. The result is that the ice crystals form a physical barrier within the probe that disrupts the measurement of total pressure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The particular type of ice that may have been responsible was a substance called &lt;em&gt;graupel&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Graupel forms when tiny supercooled water droplets adhere to snow crystals to the point that they engulf the snow crystal itself.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DmJXH.jpg&quot; alt=&quot;graupel&quot;&gt;&#xA;Graupel. Photo from Wikimedia commons&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Capt. Palmer notes factors that make graupel a possible suspect:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;No airframe icing. The supercooled water theory is discounted by the fact that the A330's icing detectors were not triggered. &lt;/li&gt;&#xA;  &lt;li&gt;Graupel has large enough particles to be audible on the voice recorder. It takes a particle with enough mass and inertia (a given density) to hit the fuselage with a sound, instead of flowing around it with the relative wind, like snow. &lt;/li&gt;&#xA;  &lt;li&gt;Graupel has enough mass to temporarily overwhelm pitot anti-icing when concentrations are high enough. The pitot tubes are hot. But even if you put a snowball on a hot skillet it does not melt instantaneously. If there is enough mass in the blockage, and in combination with new particles being added to the blockage as the first ones melt, it may exceed the pitot tubes capability to melt the obstruction as fast as it is introduced. Graupel is of significantly higher density than snow. &lt;/li&gt;&#xA;  &lt;li&gt;Graupel has sufficient blocking properties to prevent efficient transmission of dynamic pressure within the pitot tube.For example, water can flow and transmit pressure within the pitot tube, though it too can alter pitot-static readings, a physical non-fluid blockage could shield the pressure sensing port. &lt;/li&gt;&#xA;  &lt;li&gt;The likely presence of snow or similar form, as evidenced by the St. Elmo's fire discussed by the crew. The accident report stated that the sound of ice crystals hitting the aircraft can be heard about 20 seconds before the airspeed loss and autopilot disconnect.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It must be noted that the exact cause of icing problems on the A330 was never completely identified but it was specific to the particular brand of pitot tubes originally installed. Airbus was in the process of replacing them all with pilot tubes from a different manufacturer.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="5517" LastEditDate="2016-07-06T13:51:53.883" LastActivityDate="2016-07-06T13:51:53.883" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24782" PostTypeId="1" AcceptedAnswerId="24822" CreationDate="2016-01-30T10:05:59.230" Score="15" ViewCount="6915" Body="&lt;p&gt;My friend showed me something which he called the glider. At a first look, it looks like it will crash, but it flew quite well:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C2aF2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C2aF2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was surprised to see it go about 25 meters (82 feet), as it was nothing but a big ring made out of paper. I thought of how it could fly, but I had no idea. I knew that it could go through air with least resistance, but it wasn't supposed to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone explain me the logic of how this flies?&lt;/p&gt;&#xA;" OwnerUserId="13170" LastEditorUserId="62" LastEditDate="2016-01-30T14:54:26.607" LastActivityDate="2017-11-09T15:27:51.170" Title="How does a ring paper airplane fly for a long distance?" Tags="&lt;aerodynamics&gt;&lt;glider&gt;&lt;paper-airplane&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24783" PostTypeId="2" ParentId="24765" CreationDate="2016-01-30T10:43:11.093" Score="13" Body="&lt;p&gt;The accepted answer is wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Triplanes have all the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9981/what-special-handling-characteristics-or-techniques-do-biplanes-have/9986?s=1%7C0.7396#9986&quot;&gt;disadvantages of biplanes&lt;/a&gt;, only more so. But they share their advantages as well, and the main reason to build them in WW I was roll maneuverability:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The reduced wingspan reduced roll inertia, which helps to accelerate quickly into a high roll rate. Note that roll authority changes linearly with span (if the ailerons are scaled with the span), but inertia will change with span squared.&lt;/li&gt;&#xA;&lt;li&gt;The reduced wingspan reduced  roll damping, so the achievable maximum roll rate is higher. The maximum roll rate is reached when the aileron-commanded rolling moment equals roll damping, and roll damping is proportional to span squared.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sopwith_Triplane&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sopwith Triplane&lt;/a&gt; became operational early in 1917, German pilots felt at a disadvantage and Reinhold Platz at Fokker created the famous &lt;a href=&quot;https://en.wikipedia.org/wiki/Fokker_Dr.I&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dr.I&lt;/a&gt;. The next generation were biplanes again, however, and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fokker_D.VIII&quot; rel=&quot;nofollow noreferrer&quot;&gt;latest Fokker creation&lt;/a&gt; of WW I was actually a monoplane. The high climb rate of the Triplane was caused by its low wing loading and high power-to-weight ratio and more due to the lightweight construction and the advances in engines than the triplane layout.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What were the advantages to having more wings?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Adding a second wing creates a lightweight, stiff box girder. As for why people added even more wings, see &lt;a href=&quot;https://aviation.stackexchange.com/questions/19361/why-do-older-airplanes-have-a-wing-on-both-the-top-and-the-bottom-of-the-aircraf/19385?s=1%7C0.6273#19385&quot;&gt;this excellent answer&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And, why don't countries use them today?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because countries don't use airplanes, pilots do.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-01-31T22:09:10.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24785" PostTypeId="2" ParentId="24712" CreationDate="2016-01-30T14:50:05.757" Score="2" Body="&lt;p&gt;Airbus WILL take off ~safely~ regardless of the pitch trim, as long as trim is in the t/o green range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adjusting the trim to the correct position, however, depending on the location of the CG for that flight, insures the aircraft handles similarly between takeoffs and rotation will be more or less standard between flights. This means the pilot can make the same side-stick input on each takeoff and get the same 3deg/sec rotation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If not properly trimmed, rotation would be faster/slower and the pilot would have to adjust for that at a critical phase of flight. Not doing a good rotation will impact t/o performance significantly.&lt;/p&gt;&#xA;" OwnerUserId="419" LastActivityDate="2016-01-30T14:50:05.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24786" PostTypeId="2" ParentId="24778" CreationDate="2016-01-30T18:07:59.893" Score="4" Body="&lt;p&gt;The differences are in the demonstrated accuracy of the ILS or RNAV equipment. Not sure if the question can be properly answered without writing a book, but digging into the documents linked by Jonathan Walters I extracted the tables below. The document is very long and full of caveats, exceptions and specifics on testing requirements, etc. and frequently refers to parameters set forth in other documents. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;CAT I&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/b9pO0.jpg&quot; alt=&quot;CAT II Vert&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/bqcMM.jpg&quot; alt=&quot;CAT I Lat&quot;&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-29A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;CAT II&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/b9pO0.jpg&quot; alt=&quot;CAT II Vert&quot;&gt;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/Fp36O.jpg&quot; alt=&quot;CAT II Lat&quot;&gt;&#xA;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-29A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;CAT III&lt;/h2&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Landing System Performance.&lt;/strong&gt;   All types of low  visibility  landings systems, including  automatic flight control, guidance for manual control, and hybrid, shall be demonstrated to achieve  the performance accuracy  with the probabilities prescribed in this section.  The performance values may  vary  where justified by  the characteristics of the airplane. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The performance criteria and probabilities are as follows: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;p&gt;(a)  Longitudinal touch down earlier than a point on the runway  200 ft. (60m) from  the threshold to a probability  of 1 x 10-6; &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;(b)  Longitudinal touch down beyond 2700 ft.(823m) from  threshold to a probability  of 1 x 10-6; &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;(c)  Lateral touch down with the outboard landing  gear more than 70 ft. (21.3m) from  runway  centerline to a probability  of 1 x 10-6. &lt;/p&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;(d)  Structural limit load, to a probability  of 1 x 10-6.  An  acceptable means of establishing  that the structural limit load is not exceeded is to show  separately  and independently  that: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;(i)  The limit load that results from  a sink  rate at touch down not greater than 10 f.p.s. or the limit rate of descent used for certification under 14 CFR part 25 subpart C (see section 25.473), whichever is the greater. &lt;/li&gt;&#xA;  &lt;li&gt;(ii)  The lateral side load does not exceed the limit value determined for the lateral drift landing condition defined in part 25, section 25.479(d)(2). &lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;p&gt;(e)  Bank  angle resulting  in hazard to the airplane to a probability  of 1 x 10-7.  A hazard to the airplane is interpreted to mean a bank  angle resulting  in any  part of the wing, high  lift device, or engine nacelle touching  the ground. 6.3.2.  Speed Control Performance.   Airspeed must be controllable to within +/- five  knots of the approach speed*, except for momentary  gusts, up to the point where the throttles are retarded to idle for landing.  For operations flown with manual control of approach speed, the flightcrew must be able to control speed to within +/- five  knots of the approach speed.&lt;/p&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-28Dappdx.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-01-30T18:07:59.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24787" PostTypeId="1" AcceptedAnswerId="24791" CreationDate="2016-01-30T18:22:18.713" Score="16" ViewCount="4108" Body="&lt;p&gt;&lt;strong&gt;Why is fuel used in some servo-systems as a hydraulic fluid (fueldraulic systems) of modern civil and military aircraft&lt;/strong&gt; such as the &lt;a href=&quot;http://www.boeing.com/commercial/777/&quot; rel=&quot;noreferrer&quot;&gt;Boeing 777&lt;/a&gt;-200/-300 (&lt;a href=&quot;http://www.pw.utc.com/PW4000112_Engine&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney PW4084&lt;/a&gt;) or the &lt;a href=&quot;https://www.f35.com/&quot; rel=&quot;noreferrer&quot;&gt;Lockheed Martin F-35 Lightning II&lt;/a&gt; (&lt;a href=&quot;http://www.pw.utc.com/F135_Engine&quot; rel=&quot;noreferrer&quot;&gt;Pratt &amp;amp; Whitney F135&lt;/a&gt;)&lt;strong&gt;?&lt;/strong&gt;&lt;br&gt;&#xA;Examples for fueldraulics are the actuation of&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fuel Valves, Start Bleed Valves, Cooling Valves,&lt;/li&gt;&#xA;&lt;li&gt;Variable (Inlet) Guide Vanes (VGV/VIGV) / Variable Stator Vanes (VSV) for the compressor, and&lt;/li&gt;&#xA;&lt;li&gt;Thrust Vectoring Exhaust Nozzles,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;see for example &lt;a href=&quot;http://www.nap.edu/read/5871/chapter/4&quot; rel=&quot;noreferrer&quot;&gt;Eder, M.: &quot;Engine Fuel System Design Issues&quot;, Aviation Fuels with Improved Fire Safety, A Proceedings, 1997&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Here is a sketch of a fueldraulic system actuating the Bleed Valve and the VIGVs for a compressor, taken from &quot;Rolls-Royce plc: The Jet Engine, 5th Edition 1996, Derby, England, ISBN 0902121235&quot;:&lt;/em&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WNKFN.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WNKFN.png&quot; alt=&quot;Fueldraulic System for the Compressor&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Are there specific reasons for not using designated hydraulic fluids&lt;/strong&gt; such as &lt;a href=&quot;http://www.eastman.com/Brands/EAS/Skydrol/Pages/Home.aspx&quot; rel=&quot;noreferrer&quot;&gt;Skydrol&lt;/a&gt; &lt;strong&gt;for all hydraulic applications?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorDisplayName="user12485" LastEditDate="2016-01-30T20:43:51.810" LastActivityDate="2018-03-04T19:36:40.180" Title="Why is fuel used as a hydraulic fluid?" Tags="&lt;aircraft-systems&gt;&lt;fuel&gt;&lt;aircraft-subsystem&gt;&lt;fuel-systems&gt;&lt;hydraulic-system&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24789" PostTypeId="2" ParentId="24773" CreationDate="2016-01-30T21:10:03.057" Score="3" Body="&lt;p&gt;To answer your questions in order:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Pitot tubes are certified to withstand icing under particular circumstances: Within a given temperature range, precipitation amount, altitude etc. If they are operated outside of those ranges then the heating systems may not be effective. In the case of AF447 it was also important that they experienced ice crystal icing and not supercooled water icing - the two respond to pitot heating differently and the same certification requirements can't be used for both.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Automated systems are not, yet, perfect at detecting icing conditions. You don't want a system where the pitot is always on, with no possibility to turn it off, for safety reasons and you don't want an automatic system because it might fail to detect icing conditions and hence not activate the heat. That said, in my experience it's very rare to have the pitot heat off: There's not really much point. The crew has to have the discipline to turn it on at the beginning of the flight but after that an automatic system is not helpful if the heat is supposed to remain on anyway.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastEditorUserId="5517" LastEditDate="2016-07-06T13:53:27.697" LastActivityDate="2016-07-06T13:53:27.697" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24791" PostTypeId="2" ParentId="24787" CreationDate="2016-01-30T21:32:02.893" Score="18" Body="&lt;p&gt;The primary reason is availability -- the high pressure fuel pump is running whenever the engine is, while the airframe hydraulic systems may not be available in case of an accessory gearbox failure, hydraulic leak, or maintenance shutoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, this keeps hydraulic lines from needing to be plumbed deep within the bowels of the engine -- this has benefits in that the hydraulic system is confined to the accessory gearbox fire zone (where the engine driven pump lives), instead of having to run in several engine fire zones.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2016-01-30T21:32:02.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24792" PostTypeId="1" AcceptedAnswerId="24831" CreationDate="2016-01-30T21:45:58.957" Score="6" ViewCount="970" Body="&lt;p&gt;My understanding is that, for flight stability, &lt;strong&gt;the center of mass must be ahead of the aerodynamic center.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been some rather big jets with 2 or 3 jet engines in the tail. Tu-154 and Boeing 727 have 3 in the tail. The DC-9 has 2, and there seem to be countless small private jets with twin engines in/near the tail, like the Learjet 45.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is the Concorde and Tu-144 which had &lt;strong&gt;a whopping 4 engines very near the tail.&lt;/strong&gt; If I'm not mistaken those were some extra-heavy engines too since they had to be supersonic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if we're putting the heavy engines in the tail, &lt;strong&gt;what is done to compensate?&lt;/strong&gt; Do they just use ballast in the nose? How is the center of mass kept under control?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few more details: Engines at the tail requires stronger (heavier) empennage, which also adds more weight in a direction we do not want our CG moving. Wings still hold the fuel, so moving the large wing/fuel mass backwards just to move the aerodynamic center backwards doesn't seem like enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I noticed that those tailed trijets and large tailed twinjets seem rather old. There don't seem to be any new designs of large commercial aircraft with tail jets. This makes me suspicious that the configuration is inefficient. However, small private jets seem to always be tailed twinjets, whether new or old designs.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-01-31T01:28:29.187" LastActivityDate="2017-12-23T18:16:48.687" Title="How is the center of mass controlled in planes with multiple tail engines?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24794" PostTypeId="1" AcceptedAnswerId="25038" CreationDate="2016-01-30T22:47:22.383" Score="10" ViewCount="1741" Body="&lt;p&gt;Pilots today have more than enough technology both in the cockpit and in the infrastructure that supports them to know with great precision where they are at any given time. How/why do they still sometimes go off-course?&lt;/p&gt;&#xA;" OwnerUserId="13264" LastEditorUserId="15311" LastEditDate="2018-05-11T14:34:39.827" LastActivityDate="2018-10-11T19:04:21.907" Title="How do aircraft go off-course even with all their guidance technology?" Tags="&lt;navigation&gt;" AnswerCount="4" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="24795" PostTypeId="1" CreationDate="2016-01-30T22:55:42.603" Score="3" ViewCount="1263" Body="&lt;p&gt;I've read &lt;a href=&quot;https://aviation.stackexchange.com/questions/888/what-happens-when-an-airplane-gets-struck-by-lightning&quot;&gt;this question&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/3836/how-is-an-on-ground-lightning-strike-test-conducted&quot;&gt;this one&lt;/a&gt;, but they don't really answer my question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How or why are aircraft protected (from lightning) by a conducting skin, such as aluminum? Conductors allow current to &lt;strong&gt;flow through you!&lt;/strong&gt; Wouldn't it be better to have an insulating shell?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize its not possible to have an ideal bubble completely protecting you, because the engines need to breathe air. Presumably these metal engines would then take the brunt of the lightning strike.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So let me try an example with a glider. Let's say we have a glider completely surrounded by an insulating skin. Just for the sake of ideal example, let's say this skin is &lt;strong&gt;the best material insulator known: diamond.&lt;/strong&gt; (Okay, it's not solid diamond. It's just a diamond coating. Yes, they can build that via chemical vapour deposition. I know it's not economical, it's just for the sake of an ideal example.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would happen if this craft gets struck by lightning? Please don't say &quot;it explodes&quot; without some kind of citation or explanation or I will be suspicious of hollywood falsehood.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-02-01T10:21:33.940" Title="How are aircraft protected from lightning strikes by conductive skin?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;lightning&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="24796" PostTypeId="1" CreationDate="2016-01-30T23:16:29.443" Score="2" ViewCount="230" Body="&lt;p&gt;What is the most efficient design for an aircraft limited to a maximum velocity of 30mph at a maximum altitude of 100ft?&lt;br&gt;&#xA;The objective is to minimize drag and weight.&#xA;The payload would be 1 human, and my budget is approximately 100,000 dollars (more can be done) for materials I was thinking airloys (because they are light and strong). The end goal is to go more than 74 miles on flat train using human power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My guesses are aircrafts shaped like a sail plane or a Ground Effect Vehicles (GEVs).&lt;/p&gt;&#xA;" OwnerUserId="13265" LastEditorUserId="13265" LastEditDate="2016-02-04T02:37:31.170" LastActivityDate="2016-02-04T02:37:31.170" Title="What is the most efficient design for a human powered aircraft limited to 30mph at 100ft?" Tags="&lt;aircraft-design&gt;" AnswerCount="0" CommentCount="11" FavoriteCount="1" ClosedDate="2016-01-31T10:13:16.803" ContentLicense="CC BY-SA 3.0" />
  <row Id="24797" PostTypeId="1" AcceptedAnswerId="24800" CreationDate="2016-01-30T23:21:46.287" Score="16" ViewCount="910" Body="&lt;p&gt;On most single engine GA aircraft, testing both mags is always on the checklist. For a plane (like a Mooney M20) that doesn't have a &quot;both&quot; selector, it would seem prudent to throw the switch to verify there is not a flow issue from either tank. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any good reason why not to run this test, or is it just not considered worth the effort?&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-01-31T00:40:33.557" Title="Why isn't testing fuel flow from both tanks a run-up checklist item?" Tags="&lt;fuel-tanks&gt;&lt;preflight&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24798" PostTypeId="2" ParentId="24795" CreationDate="2016-01-30T23:39:10.180" Score="9" Body="&lt;p&gt;&lt;strong&gt;Lightning striking a metal aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A commercial aircraft [...] is struck several times during its whole service life.&lt;br&gt;&#xA;  In such a case, the airplane acts like a lightning rod. Its metal structure provides the lowest resistance for the electrical discharge on its way between the clouds and the ground. It is not uncommon that the airplane is thereby struck by a complete series of discharges, mostly between three and five, in exceptional cases up to 25.&lt;br&gt;&#xA;  Since an airplane in flight has no form of grounding, the lightning first enters the structure and leaves it again a split second later. &lt;strong&gt;The principle behind this occurrence is known&lt;/strong&gt; by most people from physics lessons in school. The airframe acts &lt;strong&gt;as a so called &quot;Faraday Cage&quot;&lt;/strong&gt;. Like an automobile body the aluminium structure, when struck by a lightning, passes the electric energy around the interior and keeps the passengers safe.&lt;br&gt;&#xA;  The crucial technical equipment is thereby also kept safe from the high voltage and the aircraft can, in most cases, proceed normally with its flight. But to play it safe every lightning strike is documented by the cockpit crew and the aircraft is treated with a special inspection routine on its next check.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Source: &lt;a href=&quot;http://www.lufthansa-technik.com/lightning-strikes&quot; rel=&quot;noreferrer&quot;&gt;&quot;Lightning Strikes During Flight&quot;, Lufthansa Technik&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Lightning striking modern aircraft with composite structures&lt;/strong&gt; (as noted by &lt;a href=&quot;https://aviation.stackexchange.com/questions/24795/how-are-aircraft-protected-from-lightning-strikes-by-conductive-skin/24798#comment58202_24795&quot;&gt;this comment&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Composite parts that are in lightning-strike prone areas must have appropriate lightning protection. [...] Composite structures are less conductive than metal, causing higher voltages.&lt;/strong&gt;&lt;br&gt;&#xA;  Lightning protection on airplanes may include wire bundle shields, ground straps, composite structure expanded foils, wire mesh, aluminum flame spray coating, embedded metallic wire, metallic picture frames, diverter strips, metallic foil liners, coated glass fabric, and bonded aluminum foil.&lt;br&gt;&#xA;  Lightning can also damage composite airplane structures if protection finish is not applied, properly designed, or adequate. This damage is often in the form of burnt paint, damaged fiber, and composite layer removal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Source: &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot; rel=&quot;noreferrer&quot;&gt;&quot;Lightning Strikes: Protection, Inspection, and Repair&quot;, Boeing, 2012&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;New technology improving the lightning protection of modern aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer.&lt;br&gt;&#xA;  &lt;strong&gt;A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces.&lt;/strong&gt; The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a &quot;Smart skin&quot; surface for aircraft lightning zones certified to withstand strikes up to 100 kiloamperes peak current.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Source: &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=20150001257&quot; rel=&quot;noreferrer&quot;&gt;Szatkowski, G. N. at al.: &quot;Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications&quot;, NASA, 2014&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Further information can be found on the internet, see for example &lt;a href=&quot;https://www.nasa.gov/larc/lightning-tests&quot; rel=&quot;noreferrer&quot;&gt;&quot;Playing with Lightning in the Name of Aircraft Safety&quot;, NASA&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the science behind the Faraday Cage and lightning striking insulators, please refer to &lt;a href=&quot;https://physics.stackexchange.com/&quot;&gt;Physics.SE&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-01-31T10:37:18.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24799" PostTypeId="1" AcceptedAnswerId="24801" CreationDate="2016-01-30T23:42:01.853" Score="20" ViewCount="2259" Body="&lt;p&gt;This is sort of the reverse of an &lt;a href=&quot;/questions/tagged/aircraft-identifcation&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;aircraft-identifcation&amp;#39;&quot; rel=&quot;tag&quot;&gt;aircraft-identifcation&lt;/a&gt; question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am attempting to build a virtual model of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Gee_Bee_R-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gee Bee R1&lt;/a&gt; (for fun). Unfortunately I haven't had much luck finding plans or images of the inside of an R1 cockpit. The best I could find is &lt;a href=&quot;http://www.rcuniverse.com/forum/giant-scale-aircraft-3d-aerobatic-110/1029475-composite-arf-33-gee-bee-r2-first-flight-pics-videos-l-k-27.html#post10193697&quot; rel=&quot;nofollow noreferrer&quot;&gt;this image&lt;/a&gt; of a miniature model of a R2 instrument panel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KEwh3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KEwh3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this still from &lt;a href=&quot;https://youtu.be/8nStjpGgc28?t=9m15s&quot; rel=&quot;nofollow noreferrer&quot;&gt;a video&lt;/a&gt; about a modern-day flying replica (also an R2):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YDC2Z.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YDC2Z.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having desperately reached as far as the second page of google images without success, I've given up trying to find anything better. &lt;em&gt;But if anyone knows some better sources, please let me know!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With very limited actual knowledge about any sort of aircraft, I have no idea which doohickeys do what. So my actual question is, can anyone identify what each of these things likely indicates or does?&lt;/p&gt;&#xA;" OwnerUserId="9153" LastEditorUserId="3230" LastEditDate="2020-03-25T20:41:55.367" LastActivityDate="2020-03-27T01:53:21.543" Title="What do these instruments do?" Tags="&lt;flight-instruments&gt;&lt;aircraft-identification&gt;&lt;gauge&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="24800" PostTypeId="2" ParentId="24797" CreationDate="2016-01-31T00:40:33.557" Score="15" Body="&lt;p&gt;There is a very good reason not to run this test: If it is not done perfectly your engine can become starved of fuel during takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity let's assume your fuel selector only has two positions (Left and Right) and think about what's involved in the test and a few things that can go wrong:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What are we testing?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;One of the points of an engine Runup is to verify that the fuel system can deliver a fuel flow sufficient to allow the engine to develop takeoff power. There are other things we're verifying but let's stick with that item for this discussion.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;How can we verify this?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;We verify that the fuel system has adequate flow by running the engine up to something resembling takeoff power (most runup checklists don't have you go to full throttle, but you advance the throttle enough that the engine is demanding a significant fuel flow compared to idling and taxiing around).&lt;br&gt;&#xA;To verify that your fuel system is allowing sufficient fuel flow from each tank you would have to switch tanks during the engine run-up (with the engine at runup power) and wait long enough to exhaust any fuel that might be in the system between the fuel selector and the engine.&lt;br&gt;&#xA;If the fuel selector handle comes off in your hand or the engine quits you found the problem on the ground, so you can get a tow back to the ramp and get the fuel system fixed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What can go wrong?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The test above sounds innocent enough, but it's &lt;em&gt;deceptively&lt;/em&gt; dangerous.&lt;br&gt;&#xA;Here are two possible failure modes that may make you rethink it:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;The second tank doesn't have adequate fuel flow&lt;/strong&gt;.&lt;br&gt;&#xA;This could be a complete obstruction of the tank pickup or just a restriction in one of the lines, but for some reason the second tank will not supply a fuel flow sufficient for takeoff and climb out at full power.&lt;br&gt;&#xA;You may miss this if you don't wait long enough at runup power after switching tanks to drain the fuel from the system forward of the fuel selector, and now your engine suddenly got quiet as you're rolling down the runway - or worse it quits 100 feet off the ground and now you're having a &lt;em&gt;Really Bad Day&lt;/em&gt;!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You missed the fuel selector detent&lt;/strong&gt;.&lt;br&gt;&#xA;Easy enough to do, especially if fuel selector maintenance has been lacking and the positions are not really distinct (when is the last time you *really, critically, felt the clicks on &lt;em&gt;your&lt;/em&gt; plane?). It could happen in the initial switch, or when switching back to the first tank if that's your procedure.&lt;br&gt;&#xA;A fuel selector not in a specific tank position may still allow enough fuel flow to complete a runup when combined with the fuel left forward of the fuel selector, but it may be too restricted to allow a takeoff. The fuel selector may also vibrate into an OFF position during takeoff.&lt;br&gt;&#xA;In this scenario maybe your engine stops at 200-300 feet, but you're still having a &lt;em&gt;Really Bad Day&lt;/em&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In both of these scenarios the engine is still running because there is fuel in the system between the fuel selector and the engine (the two big reservoirs are the fuel strainer / gascolator &amp;amp; the carburetor float bowl, but there are also fuel lines that will need to drain before the engine dies).&lt;br&gt;&#xA;To get an idea how long these reserves last try setting your engine to Runup power and turning off the fuel selector. You may be surprised how long the engine will run before the fuel after the selector is exhausted. Also remember the time will vary based on power setting, mixture setting, and even aircraft attitude sitting on the ground allowing more or less fuel to get to the carburetor from the lines (a nose-high attitude during takeoff may starve your engine more quickly than sitting level on the runup pad).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;How can we &lt;em&gt;safely&lt;/em&gt; conduct this test?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Making sure your fuel tanks all work is kind of important, especially if you are going to be making a flight near the endurance limit of your fuel.&lt;br&gt;&#xA;There is no 100% safe way to conduct this test, but the way I was taught seems to have the fewest possible failure modes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Start, taxi, Runup, and takeoff should be conducted on one tank.&lt;/strong&gt;&lt;br&gt;&#xA;Typically this is &quot;the fullest tank&quot;, but if they're all equally full then either the one the fuel system return flows to if your airplane has such a thing, or just pick one.&lt;br&gt;&#xA;By using the one tank for all your ground operations and your Runup you are pretty much guaranteeing that it flows sufficient fuel to allow a takeoff, and that at least this position on the fuel selector works.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;After takeoff switch tanks after reaching a safe altitude.&lt;/strong&gt;&lt;br&gt;&#xA;Do this with enough fuel left in the tank you took off on to turn around and get back to where you started in case you discover the tank you switched to doesn't work, and as with any tank switch be prepared for the fuel selector handle to come off in your hand: Know where you'll put the plane if that happens!&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;If your engine stops a few minutes after you switch tanks…&lt;/strong&gt;&lt;br&gt;&#xA;…you now have a good reason to suspect that the tank you switched to doesn't work.&lt;br&gt;&#xA;Per the first rule of troubleshooting, undo the last change you made (switch back to the working tank you took off on) and wait for the engine to get fuel again. When the engine restarts go home: You have a fuel system problem and need to get it fixed.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;If after switching back to the working tank your engine &lt;em&gt;doesn't&lt;/em&gt; restart…&lt;/strong&gt;&lt;br&gt;&#xA;…make sure you've waited long enough (it doesn't take long, but it &lt;strong&gt;&lt;em&gt;FEELS&lt;/em&gt;&lt;/strong&gt; like a long time when the engine is quiet).&lt;br&gt;&#xA;If you waited long enough you may have a fuel selector failure. These don't happen often, but they do happen (and this is why you do the test at a safe altitude with a landing spot picked out).&lt;br&gt;&#xA;In this unfortunate case run your engine failure checklist and expect to be making that dead-stick landing: Fixing a fuel selector in flight is probably beyond the skills and daring of most pilots.&lt;br&gt;&#xA;(Of course you expected this because every time you touch that fuel selector handle you expect it to come off in your hand like I said before, right? Your CFI was like mine and a few minutes after you switched tanks they pulled the throttle on you al the time, so you got this landing made, &lt;em&gt;Right?&lt;/em&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The test process I use and have outlined above is obviously not free of risk, but the risk level is reduced to be the same as any other fuel tank change: You can be reasonably sure that you &lt;em&gt;won't&lt;/em&gt; have an engine failure on takeoff when you're close to the ground, trees, people, and other things we try not to hit with our airplanes, and you can pick when you take on the risk of an engine failure to be sure you can safely recover from the situation.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-01-31T00:40:33.557" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24801" PostTypeId="2" ParentId="24799" CreationDate="2016-01-31T01:22:35.263" Score="42" Body="&lt;p&gt;For the panel image that you provided, I should be able to identify all major instruments:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tCk1j.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tCk1j.jpg&quot; alt=&quot;Annotated Panel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A: Magnetic Compass&lt;/strong&gt; - Pretty self explanatory. Note that in the real aircraft, A and K may have been switched.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B: Vertical Speed Indicator (VSI)&lt;/strong&gt; - Indicates vertical speed, either up or down, in feet per minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;C: Engine Tachometer&lt;/strong&gt; - Indicates engine revolutions per minute (RPM)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;D: Sensitive Altimeter&lt;/strong&gt; - Indicates feet above Mean Sea Level (MSL). Adjustable for atmospheric pressure via Kollsman knob.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;E: Air Speed Indicator&lt;/strong&gt; - Measures indicated air speed, most likely given in MPH for this vintage aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;F: Artificial Horizon&lt;/strong&gt; - Gyro instrument giving an indication of an artificial horizon; shows pitch and bank variations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;G: Amp and Volt Meter&lt;/strong&gt; - Amps are indicated on the left, volts on the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;H: Oil Pressure and Temperature Gauge&lt;/strong&gt; - Oil pressure is indicated on the left, in PSI, and Temperature is indicated on the right, in °C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I: Clock&lt;/strong&gt; - Probably an &quot;8-Day&quot;, spring driven, hand wound device.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;J: Magneto Switch&lt;/strong&gt; - Control for ignition systems. This control only shows three detents. There should probably be four detents: Off, L, R, and Both (L and R refer to Left and Right magnetos).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;K: Directional Gyro with Inclinometer&lt;/strong&gt; - The bottom part is the Inclinometer (ball), indicates coordination and skid or slip. The top part is the Directional Gyro. Note that in the real aircraft, K and A may have been switched. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inscription reading &quot;NR2100&quot; is indeed the aircraft registration, typically used as part of the aircraft callsign.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The knob below &lt;strong&gt;A&lt;/strong&gt; is likely used to set the gyro compass (K) that should be in that location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The knob below &lt;strong&gt;F&lt;/strong&gt; is likely to adjust the pitch indication on the artificial horizon (F).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The red knob between &lt;strong&gt;F&lt;/strong&gt; and &lt;strong&gt;E&lt;/strong&gt; is probably meant to be a knob to cage the artificial horizon (F) and should actually be placed in the location of the screw directly above and left of that red knob. See the Bee Gee Z panel I linked to below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The knob between &lt;strong&gt;E&lt;/strong&gt; and &lt;strong&gt;D&lt;/strong&gt; is probably meant to be a larger knob that might be part of a pull control. I have no real idea of what it is, but my guesses would start with carb heat, primer, starter engagement pull knob. Could be many other possible functions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reference the photos in &lt;a href=&quot;http://rogerritter.com/images/aviation/Mu1GeeBeeZ/index.html&quot; rel=&quot;noreferrer&quot;&gt;this album by Roger Ritter&lt;/a&gt; depicting a Bee Gee Model Z. I understand that it is not the same model that you are looking for, but the cockpit layout is very similar, and should be informative. His photos helped me confirm the identification of the gauges in the panel image you provided. Photo album linked only, due to image copyrights.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2020-03-27T01:53:21.543" LastActivityDate="2020-03-27T01:53:21.543" CommentCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="24802" PostTypeId="1" CreationDate="2016-01-31T02:19:35.453" Score="-2" ViewCount="950" Body="&lt;p&gt;There is a belief that wrench size is the across the flat distance of a bolt head/nut. any reason other than this for designing wrenches in these standard sizes?&lt;/p&gt;&#xA;" OwnerUserId="13268" LastActivityDate="2016-01-31T04:44:49.390" Title="why standard wrenches are sized like 1&quot;,15/16&quot;,7/8&quot;,1/4&quot; etc?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-01-31T05:20:43.157" ContentLicense="CC BY-SA 3.0" />
  <row Id="24803" PostTypeId="1" CreationDate="2016-01-31T02:38:34.687" Score="6" ViewCount="967" Body="&lt;p&gt;Why is the surge line of an aeroengine curved? Why is it not a straight line?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4iEPw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4iEPw.jpg&quot; alt=&quot;Surge diagram of an aeroengine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13133" LastActivityDate="2016-05-06T15:44:26.533" Title="Why is the surge line curved?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24804" PostTypeId="2" ParentId="24802" CreationDate="2016-01-31T04:44:49.390" Score="1" Body="&lt;p&gt;Spanners and all hand tools are based on the bolt head size, eg, 3/8&quot; across the top of the flats of the bolt head, note, this is not the bolt shank size, the threaded part. Because most widespread use of tools began in the US, the Imperial system of tool sizing came from there. In the last 30 or so years, the metric system has become widespread, but as aviation is largely based on the US system, the imperial system of measurement largely remains. There were some other forms of tool measurements uses, the UK BAE and Whitworth sizes but fortunately, these never became widespread, otherwise, your toolbox became a nightmare of tool sizes. Yes, been there, had that.&lt;/p&gt;&#xA;" OwnerUserId="13269" LastActivityDate="2016-01-31T04:44:49.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24805" PostTypeId="2" ParentId="9760" CreationDate="2016-01-31T04:51:14.697" Score="-1" Body="&lt;p&gt;Because it was a pain in the a*** to work on. The only benefit the aircraft had was it's ability to operate in noise curfew limited airports (yes, it had an attribute, it was very quiet). Maintenance manhours were very high compared to other aircraft. Engine changes, too many, compared to other aircraft, engine issues, too many, cockpit design, antiquated, spar issues, the list goes on.&lt;/p&gt;&#xA;" OwnerUserId="13269" LastActivityDate="2016-01-31T04:51:14.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24806" PostTypeId="2" ParentId="9454" CreationDate="2016-01-31T05:00:31.800" Score="0" Body="&lt;p&gt;Modern aircraft generally have a &quot;master warning&quot; and &quot;master caution&quot; warning lights which direct the pilot to scan the panel to identify the failed system. Master Warnings impact directly on the safety of flight, master cautions are the &quot;need to know about but don't panic yet&quot; systems, eg, an engine fire is a master warning (yes, there's lots of other alarms going off for this as well), but an oil pressure drifting outside of it's normal operating range or a diminishing hydraulic quantity would only trigger the master caution. &lt;/p&gt;&#xA;" OwnerUserId="13269" LastActivityDate="2016-01-31T05:00:31.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24807" PostTypeId="2" ParentId="24776" CreationDate="2016-01-31T05:07:13.887" Score="1" Body="&lt;p&gt;Outflow valve, controls cabin pressurisation. To pressurise the cabin, close this valve. Pump air into the cabin, stop the air flowing out, cabin pressurises. The valve doesn't completely close, but is about 98% closed. You still need some airflow going through the cabin. The cabin is pressurised to give an approximate equivalent altitude of 8,000 ft, whilst the aircraft is flying at 30,000 ft+.&lt;/p&gt;&#xA;" OwnerUserId="13269" LastActivityDate="2016-01-31T05:07:13.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24809" PostTypeId="1" AcceptedAnswerId="24812" CreationDate="2016-01-31T14:27:48.900" Score="19" ViewCount="12156" Body="&lt;p&gt;Air is taken from the compressors, then it is cooled by the air that comes from the ram air inlet. After that, it is compressed and cooled again by an expansion turbine. When finally air is condensed, it mixes with bypass bleed air. What is bypass bleed air? &lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-07T23:08:50.303" LastActivityDate="2020-12-19T17:00:34.883" Title="Why is air mixed with bypass air on the A/C of an aircraft?" Tags="&lt;aircraft-systems&gt;&lt;cabin-pressure&gt;" AnswerCount="6" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24811" PostTypeId="2" ParentId="24809" CreationDate="2016-01-31T14:47:16.790" Score="4" Body="&lt;p&gt;There are 4 phases to an internal combustion engine, even a gas turbine: &lt;strong&gt;suck, squeeze, bang, blow&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Suck: Air is sucked into the engine&lt;/p&gt;&#xA;&lt;p&gt;Squeeze: The air is compressed by the turbine&lt;/p&gt;&#xA;&lt;p&gt;Bang: The concentrated air is mixed with fuel and ignited.&lt;/p&gt;&#xA;&lt;p&gt;Blow: The expanded gases from the ignited fuel push out the back of the jet&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;Bleed air&lt;/em&gt; is taken out of the engine after &lt;em&gt;squeeze&lt;/em&gt; but before &lt;em&gt;bang&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-31T14:47:16.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24812" PostTypeId="2" ParentId="24809" CreationDate="2016-01-31T16:12:39.067" Score="17" Body="&lt;p&gt;You almost have the answer in your question; bleed air is hot, compressed air taken from the engine compressors.  Bypass bleed air here refers to some of that air which is bled off the engine, but not routed through the air cycle machine (pack).  When the air comes out of the pack, its really cold.  The pilot has a knob which blends the cold air from the pack with the hot bypass air to adjust the temperature that comes through the actual ductwork; this is similar to the blender box in a car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/aiER6.png&quot; alt=&quot;bleed air system 737&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in this image taken from &lt;a href=&quot;https://aviation.stackexchange.com/a/15197&quot;&gt;this answer on SE Aviation&lt;/a&gt;, the bleed air from the engine comes in at the top right corner, and you can see the line for bypass bleed air along the top of the diagram in the pipe labelled &quot;hot air&quot;.&lt;/p&gt;&#xA;" OwnerUserId="7365" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-02-01T07:28:58.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24813" PostTypeId="2" ParentId="24809" CreationDate="2016-01-31T16:34:45.017" Score="4" Body="&lt;p&gt;The Environmental Control System (ECS) which supplies air to the cabin usally uses bleed air from the engines in most aircraft. The figure below shows the engine bleed air system in a Boeing 767.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pJ87X.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pJ87X.jpg&quot; alt=&quot;767 ECS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;em&gt;Commercial Airliner Environmental Control System- Engineering Aspects of Cabin Air Quality&lt;/em&gt; by Elwood H. Hunt et. al, from Boeing&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main air supply for the ECS usually comes from the compressor, where air is taken from high/low pressure areas. These are used during different phases of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air is sometimes taken from the bypass air of the engines for the purposes of cooling. As the air is compressed in the compressor, the temperature of the bleed air rises (especially the one from HP stage) and the bypass air is used to cool it.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-31T16:34:45.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24815" PostTypeId="1" AcceptedAnswerId="24816" CreationDate="2016-01-31T17:38:28.910" Score="5" ViewCount="560" Body="&lt;p&gt;I recently came across this screenshot of a VFR flight plan.  Does anyone know what software was used to generate it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/neIlA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/neIlA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7084" LastActivityDate="2016-01-31T20:32:21.990" Title="What software generated this VFR flight plan?" Tags="&lt;flight-planning&gt;&lt;visual-flight-rules&gt;&lt;software&gt;&lt;flight-plans&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24816" PostTypeId="2" ParentId="24815" CreationDate="2016-01-31T18:05:50.373" Score="6" Body="&lt;h1&gt;This flight plan was generated with Skyvector&lt;/h1&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://skyvector.com/?ll=36.21118692508942,-115.19384765225689&amp;amp;chart=301&amp;amp;zoom=10&amp;amp;fpl=%20KMEV%20KBIH%20KVGT%20KIGM%20KINW%20KGUP%20E80%20KSXU%20KTDW%20KOJA%20KTUL&quot; rel=&quot;nofollow noreferrer&quot;&gt;Click here for the specific flight plan from your example&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Then click &amp;quot;Nav Log&amp;quot; for the log itself.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KP7Sp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KP7Sp.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-01-31T20:32:21.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24818" PostTypeId="1" CreationDate="2016-01-31T19:22:15.247" Score="5" ViewCount="10525" Body="&lt;p&gt;&lt;strong&gt;For an aircraft engine, what is the difference between a gearbox and a transmission?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was of the understanding that a transmission is a type of gearbox. For example, in a helicopter, a transmission is used in to convert horizontal rotation of the turbo-shaft to a vertical shaft rotation. Is an aircraft engine gearbox and aircraft engine transmission the same thing? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there other types of gearboxes used in aircraft engines besides the transmission design?&lt;/p&gt;&#xA;" OwnerUserId="13277" LastEditorUserId="12720" LastEditDate="2016-01-31T22:14:13.923" LastActivityDate="2016-01-31T23:38:05.607" Title="What is the different between an aircraft engine gearbox and an aircraft engine transmission?" Tags="&lt;aircraft-subsystem&gt;&lt;accessory-drives&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24819" PostTypeId="1" AcceptedAnswerId="24827" CreationDate="2016-01-31T21:17:23.233" Score="10" ViewCount="5036" Body="&lt;p&gt;The metal fuselage of an aircraft, being highly conductive, protects occupants, interior components and fuel from the effects of lightning by conducting the electricity around them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some newer aircraft, such as B787 have a fuselage made entirely out of composite materials. The major portion of the 787 is made from carbon fiber plastic laminate.&lt;sup&gt;[1] &lt;/sup&gt; Although carbon fiber conducts electricity it has a higher electrical resistance.&lt;sup&gt;[2][3]&lt;/sup&gt; Higher resistance means more heat generated by the material. And carbon fiber makes up only a percentage of the composite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has the composite material been found to have enough conductivity to deal with a direct lightning strike without damage to either the material itself or the contents of the plane? Or do designers deal with lightning strikes in some other way?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[1]&lt;/sup&gt; Boeing 787 Systems Manual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[2]&lt;/sup&gt; &lt;a href=&quot;https://van.physics.illinois.edu/qa/listing.php?id=22662&quot;&gt;Department of Physics&#xA;University of Illinois at Urbana-Champaign website&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;[3]&lt;/sup&gt; Electrical and mechanical properties of electrically conductive polyethersulfone composites. Lin Li and D.D.L. Chung, 1991, State University of New York at Buffalo. &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;source=web&amp;amp;rct=j&amp;amp;url=http://wings.buffalo.edu/eng/mae/cmrl/Electrical%2520and%2520mechanical%2520properties%2520of%2520electrically.pdf&amp;amp;ved=0ahUKEwiB-eGi9tTKAhUJWSYKHUIcD6AQFggiMAI&amp;amp;usg=AFQjCNFQt09XdedJmABPuT1-AAD3eLVt1g&amp;amp;sig2=esCxMZnsOaie77F3U6z4DQ&quot;&gt;[.pdf]&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-02-01T10:19:33.917" Title="How well does a composite fuselage deal with lightning?" Tags="&lt;fuselage&gt;&lt;composite-materials&gt;&lt;lightning&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24820" PostTypeId="2" ParentId="24809" CreationDate="2016-01-31T21:24:51.303" Score="21" Body="&lt;p&gt;&lt;strong&gt;In short&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Bypass bleed air&lt;/em&gt; is a fraction of the bleed air coming from the core compressor. It's named like this because it doesn't cross the air cycle machine of the packs as does the regular bleed air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the following picture this bypass bleed air is identified as &lt;em&gt;trim air&lt;/em&gt;. Its purpose is to be mixed with cooler bleed air from the packs to modulate the temperature in the different zones.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mixing is done by the mixing and distribution unit (see more below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aAIXZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aAIXZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Use of trim air on the Airbus A320 family. (Source: &lt;a href=&quot;http://www.csner.com/temp/amm/pack.pdf&quot; rel=&quot;noreferrer&quot;&gt;A319/A320/A321 ECS Familiarization and Training Manual&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing has open a new approach for air conditioning and pressurization using ram air rather than bleed air. The first aircraft with this approach is the B787, this requires &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/article_02_2.html&quot; rel=&quot;noreferrer&quot;&gt;dedicated compressors&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air conditioning and pressurization systems on large airliners are quite similar. Here is the overall picture:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Air conditioning and a part of the pressurization are obtained using the environmental control system (ECS)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Bleed air&lt;/em&gt;, the high pressure air taken from the engine cores and APU, is very hot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Ram air&lt;/em&gt;, the cool low pressure air taken from the aircraft belly, is used to cool the bleed air in heat exchangers. This ram air, which gets warmer in the process, is rejected in the atmosphere without entering the cabin. A fan is used to create the ram air flow when the aircraft is on the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air conditioning &lt;em&gt;packs&lt;/em&gt; are mainly air cycle machines (refreshers) that receive pre-cooled bleed air and deliver air at ambient temperature. There are usually 2 or 3 packs for redundancy.&lt;br&gt;&lt;br&gt;&lt;strong&gt;Some bleed air bypasses&lt;/strong&gt; the ACM and can be used later by the mixing unit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air from the packs goes to the mixing and distribution unit which role is to mix air from packs with air already in the cabin, and deliver the result to different zones of the aircraft. &lt;br&gt;&lt;br&gt;The unit can vary temperature according to zones by mixing packs output air and &lt;strong&gt;bypass bleed air&lt;/strong&gt;. The unit also mixes air from the ground supply when at the gate and engines and APU are not running.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air in the cabin is recirculated by two or more fans which return it to the mixing unit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As air is pumped into the aircraft by the mixing unit, air also exits the aircraft through one or several &lt;em&gt;outflow valve(s)&lt;/em&gt;. The exact quantity of air leaving the aircraft is controlled so that the pressure inside the aircraft is at the required value.&lt;br&gt;&lt;br&gt;This value is usually expressed as &lt;em&gt;cabin altitude&lt;/em&gt;, that is the altitude we would find this pressure in the standard atmosphere. Pressure is about 1013 hPa at sea level and then decreases continuously when altitude increases.&lt;br&gt;&lt;br&gt;However the &lt;em&gt;cabin altitude&lt;/em&gt; doesn't climb as high as the aircraft because there would be an insufficient oxygen pressure in the cabin. The cabin altitude is kept &lt;em&gt;proportional&lt;/em&gt; to the aircraft altitude, but usually the minimum of pressure is a value equivalent to 6,000 to 6,500 ft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;All those elements are driven by controllers that can be monitored and programmed by the crew.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Let's look at the ECS for the Airbus A320.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1. Location of elements&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f4oKG.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f4oKG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(When not specified, the source of the images is the &lt;a href=&quot;http://www.csner.com/temp/amm/pack.pdf&quot; rel=&quot;noreferrer&quot;&gt;A319/A320/A321 ECS Familiarization and Training Manual&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. Packs&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A view of a pack with the triangular ram air inlet (the ram air outlet has been removed):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/670Mv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/670Mv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pack includes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Two air-to-air heat exchangers: main (MHX) and primary (PHX). Ram air is used as the heat receiver fluid for both.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A centrifugal compressor (COMP) and a turbine (TURB). They compose the air cycle machine (ACM) which cools and reduces pressure of bleed air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A reheater (RH), a condenser (COND) and a water extractor (WE) to dry bleed air.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aomHk.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aomHk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. Air cycle machine&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jtGxd.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jtGxd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4. Pack operation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pack works this way:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Hot high pressure bleed air is directed to the PHX which cools it a bit so that it can be processed more efficiently by the ACM.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cooled air is sent to the compressor. Increasing the pressure allows for more heat to be extracted in the next step. Air gets very hot again.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compressed hot air is sent to the MHX which remove as much heat as possible, possibly below the ram air temperature, which is great while on the ground.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cool air, which contains water vapor, goes to a reheater and a condenser to create liquid water, water is collected by the water separator. This water is reinjected into the ram air to cool it before it is used in the exchangers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cool air finally rotates the turbine which extracts energy from it to drive the compressor and a ram air fan. The energy loss produces a cool low pressure air which can be used in the cabin and cockpit.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The exact temperature and moisture of air delivered by the pack are obtained by mixing air from the ACM turbine, cooler air from the PHX and warmest &lt;strong&gt;bypass bleed air&lt;/strong&gt; taken upstream the MHX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Water extraction is controlled by adjusting the temperature, in the same way, of the airflow going through the condenser.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bypass bleed air&lt;/strong&gt; is also delivered by the pack to the mixing unit for zone temperature trimming.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;5. Water extractor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TuEXp.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TuEXp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Collected water is reinjected into ram air flow.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;6. Air temperature and pressure at each step&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yE7jc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yE7jc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;FCV: Flow control valve (bleed air input)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-15T10:18:51.643" LastActivityDate="2016-03-15T10:18:51.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24821" PostTypeId="2" ParentId="24819" CreationDate="2016-01-31T21:25:28.577" Score="6" Body="&lt;p&gt;&lt;strong&gt;Lightning striking modern aircraft with composite structures&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Composite parts that are in lightning-strike prone areas must have appropriate lightning protection. [...] Composite structures are less conductive than metal, causing higher voltages.&lt;br&gt;&#xA;  &lt;strong&gt;Lightning protection on airplanes may include wire bundle shields, ground straps, composite structure expanded foils, wire mesh, aluminum flame spray coating, embedded metallic wire, metallic picture frames, diverter strips, metallic foil liners, coated glass fabric, and bonded aluminum foil.&lt;/strong&gt;&lt;br&gt;&#xA;  Lightning can also damage composite airplane structures if protection finish is not applied, properly designed, or adequate. This damage is often in the form of burnt paint, damaged fiber, and composite layer removal.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Source: &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q4/4/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Lightning Strikes: Protection, Inspection, and Repair&quot;, Boeing, 2012&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;New technology improving the lightning protection of modern aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Traditional methods to protect composite aircraft from lightning strike damage rely on a conductive layer embedded on or within the surface of the aircraft composite skin. This method is effective at preventing major direct effect damage and minimizes indirect effects to aircraft systems from lightning strike attachment, but provides no additional benefit for the added parasitic weight from the conductive layer. [...]&lt;br&gt;&#xA;  &lt;strong&gt;A new multi-functional lightning strike protection (LSP) method has been developed to provide aircraft lightning strike protection, damage detection and diagnosis for composite aircraft surfaces.&lt;/strong&gt;&lt;br&gt;&#xA;  The method incorporates a SansEC sensor array on the aircraft exterior surfaces forming a &quot;Smart skin&quot; surface for aircraft lightning zones certified to withstand strikes up to 100kA peak current. SansEC sensors are open-circuit devices comprised of conductive trace spiral patterns sans (without) electrical connections. The SansEC sensor is an electromagnetic resonator having specific resonant parameters (frequency, amplitude, bandwidth &amp;amp; phase) which when electromagnetically coupled with a composite substrate will indicate the electrical impedance of the composite through a change in its resonant response. Any measureable shift in the resonant characteristics can be an indication of damage to the composite caused by a lightning strike or from other means. The SansEC sensor method is intended to diagnose damage for both in-situ health monitoring or ground inspections. [...]&lt;br&gt;&#xA;  The SansEC sensor smart skin technology provides lightning strike protection, shielding effectiveness, and opportunity to achieve in-situ damage detection and diagnostics for aerospace composite structures along with other potential beneficial functions not available from the standard LSP method.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;Source: &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=20150001257&quot; rel=&quot;nofollow noreferrer&quot;&gt;Szatkowski, G. N. at al.: &quot;Open Circuit Resonant (SansEC) Sensor Technology for Lightning Mitigation and Damage Detection and Diagnosis for Composite Aircraft Applications&quot;, NASA, 2014&lt;/a&gt; - &lt;a href=&quot;http://hdl.handle.net/2060/20150001257&quot; rel=&quot;nofollow noreferrer&quot;&gt;Download Link&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Further information can be found on the internet, see for example &lt;a href=&quot;https://www.nasa.gov/larc/lightning-tests&quot; rel=&quot;nofollow noreferrer&quot;&gt;&quot;Playing with Lightning in the Name of Aircraft Safety&quot;, NASA&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;See also this similar &lt;a href=&quot;https://aviation.stackexchange.com/q/24795/12485&quot;&gt;question&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditorDisplayName="user12485" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-02-01T10:19:33.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24822" PostTypeId="2" ParentId="24782" CreationDate="2016-01-31T21:51:38.563" Score="9" Body="&lt;p&gt;No takers? Then I'll bite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14283/how-do-paper-airplanes-create-lift-if-their-wings-are-flat&quot;&gt;This question&lt;/a&gt; addresses how paper airplanes generate lift. This lift is caused by higher pressure on the lower side and lower pressure (suction) on the upper side, and if both are added up, the chordwise pressure distribution is shown below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wprft.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wprft.jpg&quot; alt=&quot;Flat plate pressure distribution&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flat plate pressure distribution (picture &lt;a href=&quot;http://www.windsofkansas.com/atoz2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you collect all the local forces in one point, the lift acts at a quarter of the wing's chord. That is why the forward half of the paper which in the end will be bent into the ring needs to be folded onto itself: The center of gravity of the wing is also at one quarter of chord. Thus, the lift and the weight will act a the same station and no pitching moment results.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To achieve a flight distance of 25 m, your friend threw the ring with some force to give it a high initial speed. This speed would allow it to create enough lift with very little angle of attack, so it did not suffer from flow separation initially. This resulted in low drag and the high launch speed gave the ring some kinetic energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Friction slowed the ring down gradually, but the decrease in lift at lower speed was compensated by a gradual increase of the ring's angle of attack. Why would the angle be just right to prevent the ring both from rising and dropping, you might ask? Any imbalance between lift and weight would add a vertical acceleration which would immediately change the angle at which the ring hits the flow. Its chord length and inertia would prevent it from rotating nose up or down, so it would pretty much stay on its initial path until most of the speed was eaten up and the angle of attack was so high that separation sets in. At this point, the drag would go up and speed up the deceleration process, and the ring would sink to the ground.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-01-31T21:51:38.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24823" PostTypeId="1" AcceptedAnswerId="24828" CreationDate="2016-01-31T22:07:15.247" Score="5" ViewCount="1486" Body="&lt;p&gt;I am trying to figure out how a CFI knows what endorsements to give. Obviously &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22637&quot; rel=&quot;nofollow&quot;&gt;AC 61-65E&lt;/a&gt; lays them out but what if someone is coming from a unique situation? Let's say someone has a helicopter license and wants to get their private pilot? Do they have to take a knowledge test? What if someone is a sports pilot and wants to upgrade to a private pilot, what do they have to do? How do you figure it out?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="64" LastEditDate="2016-02-01T06:28:20.450" LastActivityDate="2016-02-02T14:44:47.230" Title="How does a CFI know what endorsements to give?" Tags="&lt;cfi&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24824" PostTypeId="2" ParentId="24818" CreationDate="2016-01-31T23:10:33.570" Score="1" Body="&lt;p&gt;A transmission is something usually used on a car. They have multiple &quot;gears&quot; that allow the engine to rotate at the same speed while the output rotates at progressively higher speeds. Airplanes don't use transmissions (that I know of!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A gearbox is simply a 1-gear transmission. I suppose technically it could be called a transmission. But it usually is reduction gearing that reduces the engine RPM to propeller RPM to increase the amount of torque produced by the prop. (ex: engine RPM of the turbine is 35,000 - while the prop spins at only 1700 RPM!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gearboxes are most commonly used on turboprops, but some piston engines, like Rotax, use reduction gearboxes.&lt;/p&gt;&#xA;" OwnerUserId="13281" LastActivityDate="2016-01-31T23:10:33.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24825" PostTypeId="2" ParentId="24823" CreationDate="2016-01-31T23:13:05.387" Score="1" Body="&lt;p&gt;These are good questions - I usually google the situation or search the FARs, or lastly make a phone call to your local FSDO. Each of those situations is unique / different, and sometimes even the FSDO has to do some research.&lt;/p&gt;&#xA;" OwnerUserId="13281" LastActivityDate="2016-01-31T23:13:05.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24826" PostTypeId="2" ParentId="24818" CreationDate="2016-01-31T23:38:05.607" Score="6" Body="&lt;p&gt;In aircraft, transmission usually refers to the whole system, that transmits power between two points, say between the MGB and the tail rotor. Gearbox is usually a component of the transmission system (along with shafts, for example) which is used for changing rotational speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a sense, a full transmission system is found only in helicopters, and not in fixed wing aircraft. The closest thing a fixed wing aircraft has to a transmission is the variable pitch propeller, which is analagous to the car transmission.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/arQr4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/arQr4.jpg&quot; alt=&quot;Variable pitch propeller&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By nydano - Cut away view of Hamilton Standard Propeller, CC BY-SA 2.0, $3&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, a number of aircraft have gearboxes, especially the turboprops (and some piston engines), for reducing the engine output speed before turning the propeller. The following image shows the gearbox in a GE turboshaft engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OoyRR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OoyRR.jpg&quot; alt=&quot;Gearbox&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from mrlarry.org&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbofan engines do have a gearbox, which is used to run the accessories. The compressor is usually run through a shaft from the turbine, with various turbine stages running various compressor stages, while some turbofans do use gears between turbine and compressor, called &lt;a href=&quot;https://en.wikipedia.org/wiki/Geared_turbofan&quot; rel=&quot;nofollow noreferrer&quot;&gt;geared turbofans&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft transmissions (whether helicopter or fixed wing) is usually one speed from one point to another, with speed reduction (or direction change) offered by the gearboxes.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-01-31T23:38:05.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24827" PostTypeId="2" ParentId="24819" CreationDate="2016-02-01T00:13:45.080" Score="6" Body="&lt;p&gt;In case of composite materals, the usual solution adopted for lightning protection is to have a conductive layer in the structure. Basically, this provides a continuous conductive path of low resistance over the entire aircraft exterior (fuselage, for eg), with additional protection in zones where lightning is most likely to attach (for example, the radome). This is achived usually by having a thin conductive copper mesh embedded in the structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the 787 uses two main methods to achieve lightning protection.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The fuselage has a copper mesh 'baked' into it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some of the extremeties have metal foils in it to protect against lightning strike.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The composite layup uses an expanded metal foil (EMF) in its structure to provide lightning strike protection (LSP). The EMF is usually placed above the CFRP layer, as shown below. The EMF is usually a thin, lightweight metal foil embedded in the outer laminate of the CFRP or in the surface film in some cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DLYkP.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DLYkP.png&quot; alt=&quot;LSP EMF&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;The composite structure layup shown at left consists of an expanded metal foil layer shown at right. This figure is a screenshot from the COMSOL Multiphysics® software model featured in this blog post. Copyright © Boeing&lt;/em&gt;. Imge from comsol.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;787 also uses metal foils in some extremties (wings, nacelles etc.). From &lt;a href=&quot;http://www.faa.gov/about/plans_reports/media/787_report_final.pdf&quot;&gt;787 Systems review&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Wing fuel tank skin surfaces— electromagnetic effects protection.&lt;/strong&gt; Fasteners with dielectric tops (sealant flush to the outer surface of the fuel tank skin) in combination with copper foil protect against external ignition sources such as lightning and electrostatics on the wing tank skin &#xA;  surface by diverting and distributing current.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The metal mesh is the usual method in practice at present and used in other places too, like helicopter rotor blades and fuselage. However, work is going on for using other methods like &lt;a href=&quot;http://www.compositesworld.com/articles/lightning-strike-protection-strategies-for-composite-aircraft&quot;&gt;conductive composites, conductive surface layers&lt;/a&gt; etc.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-01T00:13:45.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24828" PostTypeId="2" ParentId="24823" CreationDate="2016-02-01T01:22:05.897" Score="3" Body="&lt;p&gt;Lets cover your specific questions first. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's say someone has a helicopter license and wants to get their&#xA;  private pilot? Do they have to take a knowledge test?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(it appears I was initially incorrect and the knowledge test does not need to be &lt;a href=&quot;https://aviation.stackexchange.com/a/24837/3677&quot;&gt;repeated as per RDP's answer&lt;/a&gt;  below) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/F7DF5EE953BA576186256EE0006FD4D6?OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;According to FAR 61.63&lt;/a&gt; you don't need to retake the knowledge test &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Additional aircraft category rating. A person who applies to add a&#xA;  category rating to a pilot certificate: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;(1) Must complete the training&#xA;  and have the applicable aeronautical experience. &lt;/li&gt;&#xA;  &lt;li&gt;(2) Must have a&#xA;  logbook or training record endorsement from an authorized instructor&#xA;  attesting that the person was found competent in the appropriate&#xA;  aeronautical knowledge areas and proficient in the appropriate areas&#xA;  of operation. &lt;/li&gt;&#xA;  &lt;li&gt;(3) Must pass the practical test. &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;(4) Need not take an&#xA;  additional knowledge test, provided the applicant holds an airplane,&#xA;  rotorcraft, powered-lift, weight-shift-control aircraft, powered&#xA;  parachute, or airship rating at that pilot certificate level.&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAR's pretty much cover all the the various cases however they can be a bit confusing. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What if someone is a sports pilot and wants to upgrade to a private&#xA;  pilot, what do they have to do? How do you figure it out?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In terms of endorsements you must obtain an endorsement for what ever it is you are going to do (exam, practical test, etc.) even if you have a license in another class or category. For example if you are going to take the PPL check ride you need an endorsement for that check ride (even if you have a sport pilots license). Now when it comes to training things may differ. Your training for a PPL will obviously be shorter if you have a sport pilots license but you will still be required to take the Private Pilots Single Engine Land written test and practical test and receive endorsements to do so, to get a PPL. This site covers the &lt;a href=&quot;http://sportpilottraining.sportaviationcenter.com/private-pilot/&quot; rel=&quot;nofollow noreferrer&quot;&gt;transition from Sport Pilot to Private Pilot&lt;/a&gt; nicely. If you are transitioning from sport to private I would imagine you may be able to complete all the requirements for a PPL without having received the student solo endorsement since you could in theory have accomplished all your solo flight requirements as a sport pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Personal Note:&lt;/em&gt; Its always a good idea to speak with your DPE before taking any practical test and ask what endorsements he is &lt;em&gt;expecting&lt;/em&gt; to see in your log book (which should be the ones that are required and no more (or less for that matter)). When I went for my check ride the wording for the PPL practical endorsement had changed recently and he warned me that many instructors mess up the wording or the pre printed ones in the log book are out of date and it can be an issue. I had my instructor add the necessary line before I went for my check ride. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-02-02T14:44:47.230" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24829" PostTypeId="2" ParentId="24794" CreationDate="2016-02-01T07:56:07.933" Score="5" Body="&lt;p&gt;The navigation data (angles, coordinates) are initially numbers and must be read by human first to use the navigation systems. If the pilot misreads or wrongly interprets the initial data, the navigation tools cannot help. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This seems the reason of both &lt;a href=&quot;https://en.wikipedia.org/wiki/Varig_Flight_254&quot; rel=&quot;noreferrer&quot;&gt;Varig Flight 254&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/TWA_Flight_3&quot; rel=&quot;noreferrer&quot;&gt;TWA Flight 3&lt;/a&gt; navigation mistakes. In general cases seem rare as they require the navigators to stay disoriented for a long time, regardless of that they see, radio stations they hear, etc, etc.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-02-02T14:14:17.443" LastActivityDate="2016-02-02T14:14:17.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24831" PostTypeId="2" ParentId="24792" CreationDate="2016-02-01T09:31:04.360" Score="7" Body="&lt;p&gt;The wings are placed sufficiently far aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, moving the wings aft moves the C/G aft as well, but since the fuselage has some weight, eventually the centre of lift overtakes the centre of gravity and there you place the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A slight problem is that C/G of cargo gets quite a bit ahead of the C/G of the airframe, causing a large difference in overall C/G position between empty and loaded aircraft and a larger horizontal stabilizer is required to maintain control over the whole range. And that, of course, reduces overall efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you look at aircraft with tail-mounted engines, you'll see that it has wings further aft compared to one with wing-mounted engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that Concorde additionally could transfer fuel between forward and aft fuel tank in flight to adjust the C/G in flight to reduce the needed deflection of the elevators. But that was not because of the overall aft C/G—the centre of lift was correspondingly far aft—but because the centre of lift moves quite significantly aft in supersonic flight.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-02-01T09:31:04.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24832" PostTypeId="1" CreationDate="2016-02-01T10:59:45.497" Score="9" ViewCount="914" Body="&lt;p&gt;I took a look at &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Examples_of_Airfoils.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;some example airfoils&lt;/a&gt; and noticed they all seem to have a downward hook at the end. I believe this draws the air downwards, creating a reaction force upwards: lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now here is a typical wide-body jet profile:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xj3DZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xj3DZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice how the fuselage points upwards at the tail. I'm not talking about the vertical stabilizer, not the horizontal stabilizers either. I'm talking about the fuselage getting narrower and narrow at the tail. It tapers to a point, but the taper flows upwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure this shape has to do with avoiding tail strikes. But is seems to me like it also incurs negative lift. Does the tail draw air &lt;strong&gt;upwards&lt;/strong&gt;, creating a reaction force in the downwards direction and thus negative lift?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="12220" LastEditDate="2016-02-01T22:25:36.573" LastActivityDate="2017-02-05T16:31:14.933" Title="Do most commercial jets have a negative lifting body?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="5" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24833" PostTypeId="2" ParentId="24097" CreationDate="2016-02-01T11:02:33.237" Score="0" Body="&lt;p&gt;Airplanes with a Mixture control have internal combustion engines (like automobiles and lawnmowers, but not like jets).  An internal combustion engine runs on fuel (avgas, petrol, butane, alcohol, whatever hydrocarbon you pick...) mixed with air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ratio that the mixture of fuel and air is set to is important for several reasons:  cost of fuel, engine cooling, avoiding carbon buildup in the engine, how smooth the engine runs, how much power the engine produces, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ratio is based on the number of molecules of fuel and the number of molecules of oxygen.  Air is approximately 20% oxygen no matter if at sea level or 30,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But at sea level the air is compressed more than at 30,000 feet.  As the airplane, or you, go up in altitude the air gets &quot;thinner&quot;, or less dense.  Less dense means that the air is not as compressed.  For some volume of air, 1 cubic foot for example, higher pressure air will have more air molecules than lower pressure air.  Since air is 20% oxygen, fewer air molecules also means fewer oxygen molecules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine performs best when the air/fuel mixture ratio stays &quot;in balance&quot;, or as close to ideal as possible.  As the engine is running is pulls air into the engine, but the amount of air is based on the volume of air, not the number of molecules of air.  As the pressure decreases, so do the number of molecules.  As the aircraft climbs into thinner and thinner air the mixture must be &quot;leaned out&quot;, where the volume of fuel and the fuel molecules is reduced, to compensate for the fewer number of oxygen molecules being pulled into the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft descends into &quot;thicker&quot; air, the number of oxygen molecules increase again, so the mixture must again be adjusted by increasing the number of fuel molecules to keep the air molecules and fuel molecules at the correct ratio.&lt;/p&gt;&#xA;" OwnerUserId="13289" LastActivityDate="2016-02-01T11:02:33.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24834" PostTypeId="2" ParentId="24832" CreationDate="2016-02-01T11:05:37.743" Score="2" Body="&lt;p&gt;The entire tail (including the horizontal stabilizer) designed to have negative lift. So the negative lift on from the tail cone is not a big deal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is to create a pitch-up moment to pull the nose up which increases overall lift.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2016-02-12T16:51:56.360" LastActivityDate="2016-02-12T16:51:56.360" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24835" PostTypeId="2" ParentId="24832" CreationDate="2016-02-01T11:21:13.387" Score="0" Body="&lt;p&gt;In general a simple tapered body at an angle of attack will net zero lift, with the front pulling up and the back pulling down, resulting in a nose up torque. &lt;/p&gt;&#xA;" OwnerUserId="13290" LastActivityDate="2016-02-01T11:21:13.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24836" PostTypeId="1" AcceptedAnswerId="24846" CreationDate="2016-02-01T12:25:21.813" Score="18" ViewCount="4139" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/22456/how-is-the-length-of-a-leg-calculated?noredirect=1#comment58280_22456&quot;&gt;another question&lt;/a&gt;, I wrote&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;You only need to plan for regulatory reserves. You don't actually have to land with them&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;and @Jan replied:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;you have to declare emergency if you do cut into them though and that will quite probably get you an investigation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I have never heard that you &lt;strong&gt;must&lt;/strong&gt; declare an emergency if you cut into your reserves (regardless of the stage of flight), and I'm wondering if there is any regulation to back it up.&lt;/p&gt;&#xA;&lt;p&gt;The only reg that I could find that comes close is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=49:7.1.4.1.12.2.1.1&quot; rel=&quot;noreferrer&quot;&gt;NTSB 830&lt;/a&gt;, which lists a set of criteria for notifying the NTSB within 10 days:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) An aircraft accident or any of the following listed serious incidents occur:&lt;/p&gt;&#xA;&lt;p&gt;(1) Flight control system malfunction or failure;&lt;/p&gt;&#xA;&lt;p&gt;(2) Inability of any required flight crew member to perform normal flight duties as a result of injury or illness;&lt;/p&gt;&#xA;&lt;p&gt;(3) Failure of any internal turbine engine component that results in the escape of debris other than out the exhaust path;&lt;/p&gt;&#xA;&lt;p&gt;(4) In-flight fire;&lt;/p&gt;&#xA;&lt;p&gt;(5) Aircraft collision in flight;&lt;/p&gt;&#xA;&lt;p&gt;(6) Damage to property, other than the aircraft, estimated to exceed $25,000 for repair (including materials and labor) or fair market value in the event of total loss, whichever is less.&lt;/p&gt;&#xA;&lt;p&gt;(7) For large multiengine aircraft (more than 12,500 pounds maximum certificated takeoff weight): (a bunch of other things)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;I'm interested in the answer for Parts 91, 135, and 121, under FAA regulations.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-07-06T11:14:40.843" Title="Do I have to declare an emergency if I cut into fuel reserves?" Tags="&lt;faa-regulations&gt;&lt;emergency&gt;&lt;fuel&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24837" PostTypeId="2" ParentId="24823" CreationDate="2016-02-01T12:39:10.760" Score="4" Body="&lt;p&gt;In general, a flight instructor must demonstrate sufficient knowledge so as to be able to provide the proper endorsements for his students. This is covered both in AC &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-65E_CHG_1.pdf&quot; rel=&quot;nofollow&quot;&gt;61-65&lt;/a&gt; and in the &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-6D.pdf&quot; rel=&quot;nofollow&quot;&gt;Flight Instructor Practical Test Standards&lt;/a&gt; Task M:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Task M: Logbook Entries and Certificate Endorsements&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;References: 14 CFR part 61, AC 61-65.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Objective: To determine that the applicant exhibits instructional&#xA;  knowledge of the elements related to logbook entries&#xA;  and certificate endorsements by describing:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Required logbook entries for instruction given.&lt;/li&gt;&#xA;  &lt;li&gt;Required student pilot certificate endorsements, including&#xA;  appropriate logbook entries.&lt;/li&gt;&#xA;  &lt;li&gt;Preparation of a recommendation for a pilot practical test,&#xA;  including appropriate logbook entry for:&#xA;  a. Initial pilot certification.&#xA;  b. Additional pilot certification.&#xA;  c. Additional aircraft qualification.&lt;/li&gt;&#xA;  &lt;li&gt;Required endorsement of a pilot logbook for the satisfactory&#xA;  completion of the required FAA flight review.&lt;/li&gt;&#xA;  &lt;li&gt;Required flight instructor records.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Regarding the question: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Let's say someone has a helicopter license and wants to get their private pilot? Do they have to take a knowledge test?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.63&quot; rel=&quot;nofollow&quot;&gt;61.63&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 61.63 Additional aircraft ratings (other than for ratings at the airline transport pilot certification level).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Additional aircraft category rating. A person who applies to add a category rating to a pilot certificate:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Need not take an additional knowledge test, provided the applicant holds an airplane, rotorcraft, powered-lift, weight-shift-control aircraft, powered parachute, or airship rating &lt;strong&gt;at that pilot certificate level.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So a private pilot looking to add an additional category rating at the same certificate level need not take the aeronautical test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What if someone is a sports pilot and wants to upgrade to a private pilot, what do they have to do? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;you can find the answer in part 61.103:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Subpart E—Private Pilots&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;§61.103   Eligibility requirements: General.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;To be eligible for a private pilot certificate, a person must:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Pass the required knowledge test on the aeronautical knowledge areas listed in §61.105(b) of this part.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(j) Hold a U.S. student pilot certificate, sport pilot certificate, or recreational pilot certificate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So a sport pilot upgrading his certificate to private pilot must take the private pilot test.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-02-01T13:01:22.220" LastActivityDate="2016-02-01T13:01:22.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24838" PostTypeId="1" AcceptedAnswerId="24840" CreationDate="2016-01-31T01:03:52.140" Score="9" ViewCount="19169" Body="&lt;p&gt;What is the temperature in the storage compartment on board of a &lt;strong&gt;cargo aircraft&lt;/strong&gt;? I'm ordering a temperature-sensitive package by airmail and wouldn't want it to freeze.&#xA;There are many questions related to temperature of the luggage compartment on a passenger airplane but I didn't find anything about cargo-only aircrats. &lt;/p&gt;&#xA;" OwnerDisplayName="SomeWittyUsername" LastEditorUserId="62" LastEditDate="2016-07-05T15:00:43.777" LastActivityDate="2016-07-05T15:00:43.777" Title="Cargo aircraft temperature" Tags="&lt;cargo&gt;&lt;temperature&gt;" AnswerCount="3" CommentCount="2" ClosedDate="2016-02-01T17:43:10.223" ContentLicense="CC BY-SA 3.0" />
  <row Id="24839" PostTypeId="2" ParentId="24838" CreationDate="2016-01-31T02:27:43.413" Score="5" Body="&lt;p&gt;Temperature conditions in cargo planes are no different than passenger planes.  Interior spaces are heated to some degree, as outside temperatures at 35,000 feet are too cold and could damage all kinds of cargo if allowed to stay that low.  When they are carrying live cargo then that cargo is placed in a section of the aircraft that is heated to a warmer temperature to assure that cargo arrives alive.&lt;/p&gt;&#xA;" OwnerDisplayName="Tom" LastActivityDate="2016-01-31T02:27:43.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24840" PostTypeId="2" ParentId="24838" CreationDate="2016-01-31T02:28:03.373" Score="11" Body="&lt;p&gt;Many things including bottles containing liquids break when the temperature drops below zero, so the cargo hold is &lt;strong&gt;always maintained above freezing&lt;/strong&gt;; 7&amp;deg;C is typical (&lt;a href=&quot;http://enroute.aircanada.com/en/articles/what-temperature-is-it-in-the-baggage-hold&quot;&gt;source&lt;/a&gt;).  This applies to both pure cargo aircraft and mixed passenger/cargo airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, it's harder to control for (say) cargo sitting around on tarmac while waiting to be loaded on the plane.  Your cargo shipper can likely arrange temperature-controlled shipping for you, but at a steep extra cost, and this is usually meant for perishables where the main danger is heat, not cold.  But unless you're shipping something to/from Siberia, you'll likely be fine.&lt;/p&gt;&#xA;" OwnerUserId="3393" OwnerDisplayName="jpatokal" LastActivityDate="2016-01-31T02:28:03.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24841" PostTypeId="2" ParentId="24838" CreationDate="2016-01-31T05:31:45.933" Score="5" Body="&lt;p&gt;One more thing you should be aware of, pilots are given the cargo manifest by the load master before the flight. Sometimes, the cargo contains temperature sensitive loads and thus the crew can adjust the temperature of the cargo hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This holds true for cargo and passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if transporting live animals the temperature is increased above the &quot;normal&quot; range.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your item is suitably marked and you have notified the shipper of the same, they will ensure that it is secure during the flight. However, as mentioned by @jpatokal - your main worry would be the time it spends on the ground, being driven to-from the cargo hold, etc rather than the flight on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Check with your shipper to see what they can do to prevent any damage to your item.&lt;/p&gt;&#xA;" OwnerUserId="1049" OwnerDisplayName="Burhan Khalid" LastActivityDate="2016-01-31T05:31:45.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24844" PostTypeId="2" ParentId="24832" CreationDate="2016-02-01T17:03:30.183" Score="3" Body="&lt;p&gt;The term 'jumbo jet' refers specifically to the Boeing 747 (family). A380 is sometimes called superjumbo; the image shows a Boeing 777, which is not a jumbo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the flow over the fuselage is concerned, the flow does accelerate over the bottom rear fuselage as a result of the shaping; however, the effects of the horizontal stabilizer is predominant in this region and the effect of the fuselage in the net force produced is negligible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As can be seen from the figure, the fuselage narrows not only from bottom up (to prevent tail strike), but also on the sides (as seen in the top view) to provide a steamlined body. The net result is that the flow is three dimensional- up and towards the centre of symmetry. In some aircraft (usually cargo ones), where the fuselage upsweep is pretty steep for loading and rotation purposes, the resulting crossflow and boundary layer growth can sometimes lead to flow seperation&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of commercial airliners, the horizontal stabilizer acts as an inverted wing- the result being accelerated flow over the bottom side of the fusealge in the region. This is the most significant reason for the flow in the rear end of the fuselage, resulting in a 'negative' lift over the tail-plane region. However, if the whole fuselage is considered, it provides some &lt;em&gt;positive&lt;/em&gt; lift.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-01T17:03:30.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24845" PostTypeId="2" ParentId="24836" CreationDate="2016-02-01T17:35:30.880" Score="11" Body="&lt;p&gt;No, you don't, but per the AIM you should declare an emergency if you need priority for landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There may be some confusion here between declaring &quot;minimum fuel&quot; to ATC, and declaring an emergency. The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot;&gt;AIM 5-5-15&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Advise ATC of your minimum fuel status when your fuel supply has reached a state where, upon reaching destination, you cannot accept&#xA;  any undue delay.&lt;/li&gt;&#xA;  &lt;li&gt;Be aware this is not an emergency situation, but merely an advisory that indicates an emergency situation is possible should any undue&#xA;  delay occur.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;5&quot;&gt;&#xA;  &lt;li&gt;If the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, you should declare an emergency due&#xA;  to low fuel and report fuel remaining in minutes.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But in general there's no regulation or rule that I can find that says when a pilot must declare an emergency. The general guidance from the AIM 6-1-2 is that pilots are expected to declare an emergency when a state of &lt;em&gt;distress&lt;/em&gt; exists. The &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC orders&lt;/a&gt; 10-1-1 are a little more specific:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A pilot who encounters a Distress condition should declare an&#xA;  emergency by beginning the initial communication with the word&#xA;  “Mayday,” preferably repeated three times. For an Urgency condition,&#xA;  the word “Pan-Pan” should be used in the same manner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As for what &lt;em&gt;distress&lt;/em&gt; actually means, the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; simply says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;DISTRESS&lt;/strong&gt;− A condition of being threatened by serious and/or imminent&#xA;  danger and of requiring immediate assistance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's unlikely that cutting into fuel reserves &lt;em&gt;by itself&lt;/em&gt; would constitute a &quot;serious or imminent danger&quot; (which is why &quot;minimum fuel&quot; isn't an emergency) but on the other hand if the pilot is also unsure of his position or has other issues to deal with, then it might still be the best thing to do.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-02-01T17:35:30.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24846" PostTypeId="2" ParentId="24836" CreationDate="2016-02-01T17:36:19.487" Score="17" Body="&lt;p&gt;There seems to be no regulations that require decleration of emergency in case of using reserve fuel. US DoT &lt;a href=&quot;http://lessonslearned.faa.gov/Avianca52/INFO_08004.pdf&quot;&gt;InFO 8004&lt;/a&gt; specifically discusses this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Emergency Fuel&lt;/strong&gt;. Although not defined in the AIM or Federal aviation regulations, the  industry-wide connotation typically associated with the &#xA;  term “Fuel Emergency” is:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The point at which, in the judgment of the pilot-in-command, it is necessary to proceed directly to the airport of in tended landing due to low fuel. Declaration of a fuel emergency is an explicit statement that priority handling by ATC is both required and expected. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Noting that pilot declaring &lt;em&gt;minimum fuel&lt;/em&gt; is not an emergency,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;The act of using a portion of the reserve fuel assigned to a flight is not,  in its self a cause to declare a minimum fuel state&lt;/strong&gt; with the controlling agency. Regulations require reserve fuel to enable aircraft to maneuver, due to unforeseen circumstances. Many aircraft safely arrive at their destination having used a portion of the fuel designated as reserve. &lt;strong&gt;There is no regulatory definition as to when, specifically, a pilot must  declare “minimum fuel” or a fuel emergency&lt;/strong&gt;. Air carriers typically develop such guidance for their pilots and include it in their General Operations &#xA;  Manuals; such guidance generally  falls along the following lines:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;•Declare “minimum fuel” when, in your best judgment, any additional delay will cause you to burn into your reserve fuel.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;•Declare a fuel emergency at the point at which, in your judgment, it is necessary for you to proceed directly to the airport at which you intend to land. Declaration of a fuel emergency is an explicit statement that priority handling by ATC is necessary and expected. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis mine)&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-01T17:36:19.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24847" PostTypeId="2" ParentId="24832" CreationDate="2016-02-01T19:07:11.563" Score="-1" Body="&lt;p&gt;When a body generates aerodynamic force, most of that force will be generated very close to the leading edge, as that is where the center of pressure is located. Relatively little is happening at the trailing edge, with respect to the generation of pressure differentials - you do still need to pay attention to the trailing edge in order to ensure that airflow is smooth and doesn't 'separate', but it's not the first place you should be looking to determine if the body, as a whole, will generate lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FWIW, a lot of modern aircraft fuselages are designed as lifting bodies, in order to help improve efficiency and performance, so, on the whole, they will be generating some amount of lift throughout most, if not all stages of flight.&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2016-02-01T19:07:11.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24849" PostTypeId="2" ParentId="24832" CreationDate="2016-02-01T21:48:02.063" Score="9" Body="&lt;p&gt;You are right, the upsweep at the tailcone allows the pilot to rotate the aircraft during take-off and landing without &lt;a href=&quot;https://aviation.stackexchange.com/questions/12709/how-does-early-rotation-increase-the-likelihood-of-a-tail-strike-at-take-off&quot;&gt;touching the ground&lt;/a&gt; with the rear fuselage. When such a tail strike  happens, the aircraft needs to be inspected and repaired, and incorrect repairs after a tail strike have &lt;a href=&quot;https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123&quot; rel=&quot;nofollow noreferrer&quot;&gt;already caused loss of life&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While most Boeing fuselages show some downslope of the upper tailcone contour, this effect is even more pronounced with all Airbus aircraft except the A380. There the upper contour of the tailcone is straight. Military transports with a rear ramp show even more upsweep to keep the heavy ramp short, and most need &lt;a href=&quot;https://aviation.stackexchange.com/questions/11808/why-do-some-airplanes-have-vertical-strakes/11812#11812&quot;&gt;additional strakes&lt;/a&gt; to limit the area of separated flow there at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This upsweep adds a small downforce and, since it happens away from the c.g., a pitch-up moment. First, at the transition from the cylindrical section to the tailcone you find a strong suction peak at the high curvature region on the lower fuselage. Also, the lower side of the tailcone has a lower pressure than the upper side. Both create the downforce and the pitch-up moment. However, a three-dimensional body of a very low aspect ratio like the fuselage has a &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design/5056#5056&quot;&gt;very low lift curve slope&lt;/a&gt;, so even the strong upsweep creates a small moment when compared to the contribution of the horizontal tail surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The local flow at the tail is dominated by the wing wake. To create lift, the wing has to deflect the flow downwards, and this produces a local flow direction at the tailcone which aggravates the situation created by the upsweep. The best indication for the local direction of flow is the rain diverter above the rear fuselage door. See below the rear door of the A320: To create the lowest possible drag, the rain strip is aligned with the local direction of flow during cruise. When flying at lower speed, the downwash is even stronger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cxAuP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cxAuP.jpg&quot; alt=&quot;A320 rear fuselage&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A320 rear fuselage (own work, based on this &lt;a href=&quot;http://forum.aerosoft.com/uploads/monthly_2015_10/2015-10-27_11-38-53-114.jpg.4875042399889b4344dc6729d1b4bac8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2017-02-05T16:31:14.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24850" PostTypeId="1" AcceptedAnswerId="24859" CreationDate="2016-02-01T22:45:29.183" Score="8" ViewCount="2775" Body="&lt;p&gt;Based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/4994/why-are-delta-wings-not-commonly-used-in-commercial-airliners&quot;&gt;this&lt;/a&gt; question, it seems that delta-shaped wings do not perform well at low airspeeds. But why do paper airplanes, particularly the most well known one, fly well even though the airspeed they fly in is at most 15 knots on average?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2017-04-12T01:47:43.933" Title="Why do delta-wings perform so well on paper airplanes?" Tags="&lt;wing&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24851" PostTypeId="2" ParentId="14944" CreationDate="2016-02-01T23:25:24.050" Score="2" Body="&lt;p&gt;Simple physics means that turboprops, at low speed, give more thrust for a given amount of fuel burnt than due turbofans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Complex engineering means that building a turboprop aircraft in the 300 ton category, like the C-17, is impractical:  it would need about 120,000 shp, total.  Building the engines is fairly simple--Pratt, GE, and Rolls-Royce all make gas turbine engines that produce 30,000+ shp -- but neither the needed gearbox nor propellers are within current state of the art.  The real answer is not that Airbus was stupid or France corrupt (if you think politics doesn't come into US procurement, I've got some nice oceanfront property in Nebraska), but that the C-17 is too big for turboprops.&lt;/p&gt;&#xA;" OwnerUserId="13300" LastActivityDate="2016-02-01T23:25:24.050" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24852" PostTypeId="2" ParentId="12365" CreationDate="2016-02-02T00:36:37.970" Score="2" Body="&lt;p&gt;Pairing engines like that makes it more likely that the failure of one engine will propagate to the other.  This has happened on, for example, the F-18 where one engine had an uncontained failure, resulting in bits of engine (I think they were turbine blades) destroying the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, when you've got wing-mounted engines, spreading them out reduces wing bending moments, which tends to reduce wing weight. &lt;/p&gt;&#xA;" OwnerUserId="13301" LastActivityDate="2016-02-02T00:36:37.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24854" PostTypeId="2" ParentId="24850" CreationDate="2016-02-02T01:15:01.310" Score="6" Body="&lt;p&gt;Delta wings don't perform well at low speeds &lt;em&gt;compared&lt;/em&gt; to other low speed wings such as straight ones. The delta wings do have some disadvantages compared to the 'reguar' wings at low speeds. I'm assuming that you're talking about paper aircraft like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6mTWJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6mTWJ.jpg&quot; alt=&quot;delta&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from secretprojects.co.uk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delta wings have more friction drag, have difficulty in integrating high lift devices and have low AR etc. (as already noted in that question); however, most of these disadvantages are marginal when it comes to the paper aircraft. On the other hand, this kind of design offers some good advantages when you want it to just fly when thrown:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The delta wings still produce lift using a vortex, which means that they stall at much higher angles of attack. At low Reynolds numbers, the max. lift coeffecient is obtained at slightly higher AoA. This helps in their flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The centerfold, in addition to helping in holding and throwing, also helps in lateral stability. Also, the flow through that helps in reducing the pressure over the top surface of the paper craft, helping in increasing lift.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-02T01:15:01.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24855" PostTypeId="2" ParentId="15038" CreationDate="2016-02-02T04:19:11.080" Score="6" Body="&lt;p&gt;I always taught my students the acronym PARE:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P: Power idle. This reduces the airflow over the tail. This may seem counterintuitive, but it's about helping to lower the nose and break the stall. The less airflow over the tail, the lower its downward lift component will be. This will in turn allow the aircraft's nose to drop, helping to break the stall. &#xA;A: Ailerons neutral. This may also seem counterintuitive, as your natural urge will be to put opposite aileron in to level the wings. But in a stall, one wing is more stalled (higher angle of attack) than the other. Let's say it's the left wing. If you were to add right aileron to bring that left wing back up, that means that the left wing's aileron will go down in an attempt to create more lift on that wing. But by lowering the aileron on that wing you will actually be increasing the angle of attack on that wing, which in turn will only deepen the stall on the wing and worsen the spin. &#xA;R: Rudder full opposite the spin. This is the key step, and in most Cessnas will be enough on its own to dampen or end the spin pretty fast. It counteracts the yaw and roll of the spin. &#xA;E: Elevator nose down to break the stall (after applying the opposite rudder). This will be like an exaggerated stall recovery, as you will likely have a very nose low attitude. However, this step is key on some aircraft to break the stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All aircraft have different stall and spin characteristics. Some are certified for spins, some aren't but will recover easily, and some will not recover well at all. Consult your aircraft's POH to learn about your aircraft's characteristics and certifications, and don't attempt to learn by yourself; always fly with an instructor if you intend to practice spin recoveries. &lt;/p&gt;&#xA;" OwnerUserId="12755" LastActivityDate="2016-02-02T04:19:11.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24858" PostTypeId="1" CreationDate="2016-02-02T07:41:37.407" Score="7" ViewCount="1672" Body="&lt;p&gt;If you look at the car industry there are luxury comfort brand like Rolls Royce or Bentley but super expensive racing cars are probably even more popular. They offer limited comfort, are not practical, almost not usable on normal roads, not very reliable and offer terrible fuel consumption. But still everybody dreams about them and a lot of companies try to manufacture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Business jet can offer luxury and comfort but what to do if you want some excitement or performance? Why are there no jets with massive after burning engines with thrust bigger than weight that can climb straight up and do several G? Something like a cross-breed between a Gulfstream and an F15? Maybe it's good business case to manufacture something like this?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="3201" LastEditDate="2016-02-03T06:57:09.660" LastActivityDate="2016-02-03T06:57:09.660" Title="Are any agile (aerobatic) private jets produced?" Tags="&lt;private-jets&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24859" PostTypeId="2" ParentId="24850" CreationDate="2016-02-02T08:05:17.217" Score="12" Body="&lt;p&gt;Your interpretation of the answer to that question is a bit wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be an error to claim that delta wings &lt;strong&gt;&lt;em&gt;don't perform well&lt;/em&gt;&lt;/strong&gt; at low speed. Delta wings perform exceptionally well at low speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The correct interpretation is &lt;strong&gt;delta wings are not fuel efficient&lt;/strong&gt;. And this is true at low and high speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are advantages to delta wings at both high and low speeds. The following list are some of the known advantages:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Improved handling at high Mach numbers due to swept leading edge (note: this is the same advantage as swept wings but with the down side of being draggy when performing manoeuvres - swept wing planes retain much more kinetic energy after a turn).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Intrinsically strong structurally (it's a triangle!) thus can be built much lighter.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Retains quite a lot of rudder effectiveness at low speeds and high angles of attack (this is unintuitive because you'd think the wing would block airflow to the rudder but the strong vortex shedding on the leading edge maintains flow around the rudder).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Have very wide CG range compared to conventional aircraft. This is especially useful in bombers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Have very benign and gentle stall behaviour. This is especially useful for paper airplanes since it can prolong flight at low speeds (paper airplanes simply dip their noses and regain speed instead of simply diving and crashing).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The major disadvantage is that it is draggy. Thus not fuel efficient. Thus in a business world where profit and cost matters delta wings are not attractive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For supersonic flights the drag is apparently roughly on par with swept wings. Except, as mentioned above, due to the geometry of the wing it can be built lighter thus save fuel - so it sort of cancels out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For toy planes, where efficiency is not of great concern (fun and &quot;cool&quot; is more important) delta wings are OK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Still, if you use the same sheet of paper and built a long, narrow, cambered wing like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ff5tW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ff5tW.jpg&quot; alt=&quot;Office flyer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;.. you'll find that the long narrow winged plane flies much further than the delta wing paper airplane given the same launch speed.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastEditorUserId="2117" LastEditDate="2016-02-02T13:33:43.990" LastActivityDate="2016-02-02T13:33:43.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24860" PostTypeId="2" ParentId="24858" CreationDate="2016-02-02T10:27:39.990" Score="9" Body="&lt;p&gt;The reason these aren't built is that there's no market for them. Sure, there's loads of people who would love one of these (including me) but they would be incredibly expensive to buy and operate, far out of reach for anyone but the extremely wealthy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the airfield I fly from there are &lt;a href=&quot;https://en.wikipedia.org/wiki/BAC_Jet_Provost&quot;&gt;Jet Provosts&lt;/a&gt;, a 50's era jet trainer, available. These old, not particularly fast or agile jets cost about 1000 USD per  hour to fly. I've seen Mig-21 (certainly fast with lots of Gs) training for about $4500 per hour, which gives you an idea of the running costs for a fast, exciting jet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The existing market of people who can afford this is already supplied by military surplus jets. These run from trainers like the L-39 and Gnats to fighters and bombers like Migs, an F-104, hawker hunter, there's even a privately owned Harrier. These don't cost that much to buy considering what one would cost new, and there's plenty of them on the market, so there's no call for new builds. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-02T10:27:39.990" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24862" PostTypeId="1" AcceptedAnswerId="24866" CreationDate="2016-02-02T13:52:07.313" Score="20" ViewCount="4571" Body="&lt;p&gt;Why do blimps have fins? Can't the two (or so) engines already control direction?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Lfr7T.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Lfr7T.jpg&quot; alt=&quot;Image of blimp with rear fins&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13312" LastEditorUserId="1467" LastEditDate="2016-05-25T10:35:51.593" LastActivityDate="2019-02-21T05:45:32.413" Title="Why do blimps have fins?" Tags="&lt;aircraft-design&gt;&lt;stability&gt;&lt;balloon&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24863" PostTypeId="2" ParentId="24772" CreationDate="2016-02-02T14:00:48.317" Score="9" Body="&lt;p&gt;There are three factors: Va speed, weight, and CG limit.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Va is connected to the weight limit, not to the CG limit.  If you look at a typical V/G diagram, you'll notice that Va is defined by the load factor &lt;strong&gt;at max gross&lt;/strong&gt;. Multiplying the load factor times the weight gives the force exerted on the structure at Va.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the 172, in the normal category at max gross is 3.8G * 2400# = 9120 pounds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the utility category 4.4G * 2100# = 9240 (about the same as 9120).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the weight is limited to 2100#, the G load can be increased to 4.4, and not exceed the overall structural limits of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CG limit in the utility category is there to ensure that the CG is forward enough that the pilot can more easily recover from the maneuvers, such as stalls and spins. It probably has a lot to do with the amount of elevator authority, which is necessary to break the stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MdIoh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MdIoh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-02-02T14:00:48.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24864" PostTypeId="2" ParentId="24862" CreationDate="2016-02-02T14:09:36.137" Score="9" Body="&lt;p&gt;Fins, which are also known as &lt;em&gt;stabilizers&lt;/em&gt;, increase the horizontal and vertical stability of the blimp. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the fins the blimp would porpoise and sway, especially at low speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if the blimp encounters an updraft, the nose would want to rise up, and the tail down. The horizontal stabilizers resist the pitching moment, the same way as the feathers on an arrow.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-02-02T14:09:36.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24865" PostTypeId="2" ParentId="24862" CreationDate="2016-02-02T14:25:23.187" Score="5" Body="&lt;p&gt;The fins that are present in the blimps serve two purposes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They help in controlling the aircraft, much like the normal fixed wing aircraft- the movement of control surfaces in fins (the vertical fins and horizontal stabilizers) helps in rotation of the airship about cg while the engine (i.e. propellers) are used solely for providing thrust in the forward direction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They also aid in stability- for example, if the airship pointed into the wind turns in one direction due to a disturbance, the wind on the fins creates an opposing moment about the cg and tends to return the craft to its original position. This is especially important in case of tethered blimps or aerostats, which usually lack engines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-02T14:25:23.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24866" PostTypeId="2" ParentId="24862" CreationDate="2016-02-02T14:36:27.827" Score="27" Body="&lt;p&gt;What if the engines fail? In early airships this happened frequently, and many ships limped home on a reduced number of engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that all airships were both vertically and laterally unstable. The helmsman had to continuously adjust the rudder angle to keep the ship on course. In &lt;a href=&quot;http://hdl.handle.net/2060/19930080972&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA TN 204&lt;/a&gt;, Frank Rizzo concluded that enlarging the fins would be beneficial, and reducing them would be unwise. They were just as large as needed to control the ship, but not sufficiently large to give it static stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Static stability in aircraft means any attitude change creates forces which return the craft to its old attitude. In airships, several types of static stability must be observed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Buoyancy:&lt;/strong&gt; If the ship rises or sinks, the rate of cooling of the atmosphere and the gas in the hull might differ. If the cooling rate of the atmosphere (lapse rate) is above the adiabatic rate, the ship is unstable.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Pitch attitude:&lt;/strong&gt; If the ship pitches up or down, the lifting gas will shift towards the highest point, and the heavier gas in the ballonets will shift to the lower point, creating an unstable pitch condition.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Directional stability:&lt;/strong&gt; When moving forward, any heading change will cause a side force which is centered at the forward hull and pushes the ship further off course. The fins create a counteracting force, but due to their size this force is too small to turn the ship back. Only by adding rudder the helmsman can keep the ship stable.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Longitudinal stability:&lt;/strong&gt; In a similar way, pitching the ship up or down while in motion will create a destabilizing force on the forward hull which is mitigated, but not eliminated, by the horizontal fins. Elevator deflection is necessary to keep the ship at the desired pitch angle.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Roll stability:&lt;/strong&gt; Since the center of gravity is below the center of buoyancy, the mass of the gondola will pull an airship right side up. This is also valid when flying turns: Then the gondola will roll the ship into the turn such that a rudder command into the turn will also cause a nose-down pitching moment. Now all control surfaces need to be coordinated to keep the nose of the airship up.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that only the first and last type of static stability are ensured, and the first only for special atmospheric conditions! The other three are lacking!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Zeppelin airships used two helmsmen, one for directional and one for pitch control. Due to the size of the ships any movement was very slow, so the task of keeping them on course was easier than it might sound. However, taking any of the fins away or even reducing their size would had made the ships uncontrollable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="22726" LastEditDate="2019-02-21T05:45:32.413" LastActivityDate="2019-02-21T05:45:32.413" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="24867" PostTypeId="2" ParentId="24772" CreationDate="2016-02-02T15:01:15.157" Score="2" Body="&lt;p&gt;I think answer is simple. In utility category limit factor is higher: +4.4g. Normal category: +3.8g. You have higher limit factor so you have higher speed.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-02-02T15:01:15.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24868" PostTypeId="1" AcceptedAnswerId="24871" CreationDate="2016-02-02T16:27:58.777" Score="6" ViewCount="325" Body="&lt;p&gt;If you have a 1st, 2nd, or 3rd class medical certificate and a private balloon certificate (as an example) does that mean you have a student pilot certificate if you now want to get a private pilot certificate? Would you have to go back to a medical examiner, DPE, or FSDO to get a student pilot certificate?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="64" LastEditDate="2016-02-02T17:47:50.577" LastActivityDate="2016-02-02T18:23:32.877" Title="Does holding a medical certificate mean you automatically have a student pilot certificate?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24869" PostTypeId="1" AcceptedAnswerId="24925" CreationDate="2016-02-02T16:53:34.540" Score="4" ViewCount="712" Body="&lt;p&gt;I am trying to obtain tail numbers for some flights to retrospectively complete my 5 month old's new passenger flight log book. Antonakis, FlightRadar24 and FlightAware sites are not giving me the answers since the flights took place too long ago. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the flight information that I have:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Flight No.    Date          Route&#xA;&#xA;AC 8036       29/10/2015    YYZ-PIT &#xA;AC 8037       02/11/2015    PIT-YYZ&#xA;AC 7508       05/12/2015    YTZ-YUL&#xA;AC 7521       12/12/2015    YUL-YTZ&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Any help or instructions on where to obtain info would be greatly appreciated.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note that this question is not a duplicate.&lt;/strong&gt; This question is not answered by the question, &lt;a href=&quot;https://aviation.stackexchange.com/questions/16441/how-to-determine-the-aircraft-tail-number-on-a-particular-flight&quot;&gt;How to determine the aircraft tail number on a particular flight?&lt;/a&gt;, since these flights occured too long ago to be found through the methods discussed in the answers to that question.&lt;/p&gt;&#xA;" OwnerUserId="13314" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-04-28T11:49:29.077" Title="How might one obtain aircraft registration numbers for past flights (months ago)?" Tags="&lt;aircraft-registration&gt;&lt;tail&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24871" PostTypeId="2" ParentId="24868" CreationDate="2016-02-02T18:08:26.387" Score="9" Body="&lt;h3&gt;This answer reflects rulemaking effective 1 April 2016&lt;/h3&gt;&#xA;&lt;p&gt;Regarding the question in the title, no, holding a medical does not mean you have a student pilot certificate.  &lt;a href=&quot;https://www.federalregister.gov/articles/2016/01/12/2016-00199/student-pilot-application-requirements&quot; rel=&quot;noreferrer&quot;&gt;New regulations going into effect 1 April 2016&lt;/a&gt; separate the student pilot certificate from the combination medical+student pilot certificate.  Students will need to apply for a student pilot certificate with their CFI or with the FSDO (or their part 141 flight school) through IACRA.  The new student pilot certificate is plastic just like a normal pilot certificate and do not expire.&lt;/p&gt;&#xA;&lt;h3&gt;This part is true with or without the rulemaking changes&lt;/h3&gt;&#xA;&lt;p&gt;Regarding the question in the body of your post, you are already a certificated pilot with a balloon rating.  You are not a student pilot, you are a private pilot.  The regulations you are subject to are to add an airplane category rating are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=897ca4a9cce7ae8d0226103336ac2c3a&amp;amp;mc=true&amp;amp;node=pt14.2.61&amp;amp;rgn=div5#se14.2.61_163&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 61.63&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§61.63   &lt;strong&gt;Additional aircraft ratings (other than for ratings at the airline transport pilot certification level).&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;(a) General. For an additional aircraft rating on a pilot certificate, other than for an airline transport pilot certificate, a person must meet the requirements of this section appropriate to the additional aircraft rating sought.&lt;/p&gt;&#xA;&lt;p&gt;(b) Additional aircraft category rating. A person who applies to add a category rating to a pilot certificate:&lt;/p&gt;&#xA;&lt;p&gt;(1) Must complete the training and have the applicable aeronautical experience.&lt;/p&gt;&#xA;&lt;p&gt;(2) Must have a logbook or training record endorsement from an authorized instructor attesting that the person was found competent in the appropriate aeronautical knowledge areas and proficient in the appropriate areas of operation.&lt;/p&gt;&#xA;&lt;p&gt;(3) Must pass the practical test.&lt;/p&gt;&#xA;&lt;p&gt;(4) Need not take an additional knowledge test, provided the applicant holds an airplane, rotorcraft, powered-lift, weight-shift-control aircraft, powered parachute, or airship rating at that pilot certificate level.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As a balloon pilot seeking the airplane category rating with the single-engine land class you&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;must meet the aeronautical experience requirements in 61.109(a)&lt;/li&gt;&#xA;&lt;li&gt;must be endorsed and found competent in aeronautical knowledge of 61.105(b), 61.107(b)(1)&lt;/li&gt;&#xA;&lt;li&gt;must complete a private pilot airplane written exam&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;and then you will be able to take the practical examination and have airplane single-engine land added to your existing private pilot certificate.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-02T18:13:44.760" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24872" PostTypeId="2" ParentId="24868" CreationDate="2016-02-02T18:23:32.877" Score="1" Body="&lt;p&gt;Although the other answer is correct regarding the medical, the thing you need to know is that if you already hold a &lt;em&gt;private balloon certificate&lt;/em&gt;, you do &lt;strong&gt;not&lt;/strong&gt; need a student pilot certificate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are already a private pilot, with a balloon rating, and you are adding an airplane rating.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-02-02T18:23:32.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24873" PostTypeId="1" AcceptedAnswerId="24877" CreationDate="2016-02-02T20:07:24.970" Score="4" ViewCount="7539" Body="&lt;p&gt;I was reading this article about EICAS:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Engine-indicating_and_crew-alerting_system&quot; rel=&quot;nofollow&quot;&gt;Engine-indicating and crew-alerting system&lt;/a&gt; (EICAS) includes&#xA;  instrumentation of various engine parameters, including for example&#xA;  revolutions per minute, temperature values, fuel flow and quantity,&#xA;  oil pressure etc. Typical other aircraft systems monitored by EICAS&#xA;  are for example hydraulic, pneumatic, electrical, deicing,&#xA;  environmental and control surface systems. EICAS has high connectivity&#xA;  &amp;amp; provides data acquisition and routing.(source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Engine-indicating_and_crew-alerting_system&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Wikipedia article doesn't explain EICAS functionality very well, specially on the matter of the Crew-alerting System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested to know more about this system... So here is my questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I'm correct to assume that EICAS is a vital instrument for glass cockpits?&lt;/li&gt;&#xA;&lt;li&gt;Is every fault displayed there? (ie. Radio failure, air packs malfunctioning, etc...)&lt;/li&gt;&#xA;&lt;li&gt;What is the difference between red messages and yellow messages?&lt;/li&gt;&#xA;&lt;li&gt;How much detail can a pilot get from its messages?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="167" LastEditDate="2016-02-03T00:23:23.007" LastActivityDate="2020-01-20T23:06:43.703" Title="What details do EICAS systems provide?" Tags="&lt;emergency&gt;&lt;flight-instruments&gt;&lt;glass-cockpit&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24874" PostTypeId="1" AcceptedAnswerId="24878" CreationDate="2016-02-02T20:10:22.470" Score="7" ViewCount="1402" Body="&lt;p&gt;Does load factor limit in reality change with aircraft weight? &lt;strong&gt;Is it fixed to make certification and operation more simple?&lt;/strong&gt; Now unloaded aircraft has lower Va speed. This makes sense to keep constant maximum G. But if aircraft can sustain +2.5g at MTOW will anything break if it sustains +3.0g completely empty? As I understand wing bending force will be the same and this should be limiting factor in most aircraft? What else can break? Engines fall off? Tail breaks off? Theoretically possible but can this really happen?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-02-03T07:15:30.077" Title="Does load factor limit actually change with aircraft weight?" Tags="&lt;aircraft-performance&gt;&lt;aircraft-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24875" PostTypeId="2" ParentId="24873" CreationDate="2016-02-02T20:23:52.970" Score="1" Body="&lt;p&gt;As far as I know EICAS is used in Boeing aircraft. The wiki page you provided has a link to Airbus system as well which is much more complex and detailed. Not every fault is displayed there. Detailed list is available in Boeing manuals. For example 737NG: &lt;a href=&quot;http://www.smartcockpit.com/plane/boeing/b737ng.html&quot; rel=&quot;nofollow&quot;&gt;http://www.smartcockpit.com/plane/boeing/b737ng.html&lt;/a&gt; Look under Engines. Interestingly nowhere in manuals it's referenced by EICAS. Maybe because it's really basic for 737NG. Usually red is critical and yellow or amber is caution. And yes it's important and critical engine parameters are shown there.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="8466" LastEditDate="2016-02-02T20:35:52.430" LastActivityDate="2016-02-02T20:35:52.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24876" PostTypeId="1" AcceptedAnswerId="24881" CreationDate="2016-02-02T20:49:47.880" Score="6" ViewCount="1285" Body="&lt;p&gt;I've always been told that TODA&lt;sup&gt;*&lt;/sup&gt; = TORA&lt;sup&gt;†&lt;/sup&gt; + Clearway.  I can't really imagine what a negative clearway would be, so that leads me to think that it is required that TODA &gt;= TORA.  Interestingly, a colleague pointed out a certain airport (Invercargill, New Zealand - ICAO code NZNV) where the declared distances published by a certain source describe a TODA that is in fact less than the TORA.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My colleague and I are under the impression that some kind of typographical error has occurred when this source was publishing the data.  However, I can't help but think back to strikingly similar conversations we had after seeing a previously unheard of case where ASDA&lt;sup&gt;‡&lt;/sup&gt; &amp;lt; TORA.  As it turned out, the FAA had changed how Runway Safety Areas were considered, in such a way that it &lt;strong&gt;is&lt;/strong&gt; totally possible for ASDA &amp;lt; TORA (and we've been seeing it more and more frequently ever since).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;*&lt;/sup&gt;TODA = Take-Off Distance Available&lt;br&gt;&lt;sup&gt;†&lt;/sup&gt;TORA = Take-Off Run Available&lt;br&gt;&lt;sup&gt;‡&lt;/sup&gt;ASDA = Accelerate-Stop Distance Available&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;TL;DR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wanted to see if anyone has ever heard of any other case where TODA &amp;lt; TORA, under any regulatory agency.  What would the rationale be if that were the case?&lt;/p&gt;&#xA;" OwnerUserId="3337" LastEditorUserId="3337" LastEditDate="2016-02-03T21:25:01.873" LastActivityDate="2016-02-03T21:25:01.873" Title="Can TODA ever be shorter than TORA, under any circumstance?" Tags="&lt;aircraft-performance&gt;&lt;regulations&gt;&lt;declared-distances&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24877" PostTypeId="2" ParentId="24873" CreationDate="2016-02-02T21:01:35.480" Score="5" Body="&lt;p&gt;The EICAS will have the engine instruments and the crew alerting system in one display.  It is a vital instrument because it displays engine parameters, fuel, the crew alert system and other systems information depending on the specific airplane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CAS (crew alerting) functionality of the EICAS replaces the illuminated fault buttons in older airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dfrno.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dfrno.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/User:YSSYguy&quot; rel=&quot;nofollow noreferrer&quot;&gt;YSSYguy&lt;/a&gt; CC-BY-SA 3.0&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electronic CAS that is part of an EICAS display is a superset of these old panels and can display a much bigger set of alerts.  The specific alerts that can be shown will cover most error and failure modes the airplane systems can reasonably encounter.  Cautions are yellow in color and will illuminate the master caution and sound an audible chime.  Warnings are red in color and will &#xA;illuminate the master warning and sound the triple chime (and the fire bell for certain conditions).  There may also be advisory messages displayed in another color, e.g. cyan, on the EICAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p8RcL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p8RcL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sub&gt; EMB-145 EICAS.  The CAS is the upper right portion of the display&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The messages themselves are terse and not detailed, though detail can be inferred from the pre-defined message text.  Warnings and cautions that are displayed can be addressed with memory immediate action items (memorized checklists) and/or the QRH (quick reference handbook) which defines the procedures for dealing with problems in a verbose checklist flowchart.  The QRH will be indexed by the messages on the CAS so they can be easily found and referenced.&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-02-02T21:01:35.480" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24878" PostTypeId="2" ParentId="24874" CreationDate="2016-02-02T21:04:59.360" Score="6" Body="&lt;p&gt;Yes, the limits are always set by the worst combination of weight, loading, flight speed and expected gust speed. They are valid over the full range of parameters for simplicity reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the load factor limits are not directly proportional to the aircraft's overall weight, but the &lt;a href=&quot;https://aviation.stackexchange.com/questions/18912/why-does-maneuvering-speed-vary-with-weight/18932#18932&quot;&gt;weight of the non-lifting parts&lt;/a&gt;. An empty fuselage and full wing tanks allow the aircraft to pull more gs or fly faster until the maximum wing bending moment is reached when flying through the maximum expected gust. Calculating the precise load limit during each stage of a flight would put excessive demands on any pilot and increase the risk of errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All components should be sized so that they fail at 150% of calculated maximum loads. In real aircraft some secondary considerations like the availability of sheet metal gauges or extruded profiles put a limit to this local optimization, but technically the chance for breaking is the same for all structural parts. All the failures described in your question have happened in the past when aircraft were overstressed or improperly designed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-02-03T07:15:30.077" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24880" PostTypeId="1" CreationDate="2016-02-03T01:17:33.143" Score="2" ViewCount="526" Body="&lt;p&gt;Where can I find the records of which airplane model and creation number was delivered to which airline in which year for Boeing (Like B737-300 number 32 was delivered to Lufthansa in 1980)?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="5517" LastEditDate="2016-07-07T14:27:07.933" LastActivityDate="2016-07-07T14:39:26.720" Title="Where can I find information about Boeing delivery history?" Tags="&lt;aviation-history&gt;&lt;boeing&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ClosedDate="2020-07-07T22:21:56.517" ContentLicense="CC BY-SA 3.0" />
  <row Id="24881" PostTypeId="2" ParentId="24876" CreationDate="2016-02-03T01:38:36.180" Score="8" Body="&lt;p&gt;&lt;strong&gt;No&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Takeoff Distance Available (TODA) can never be shorter than Takeoff Run Available (TORA).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AIM 4-3-6 &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Takeoff Distance Available (TODA) – The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I had previously downloaded the FAA runway database and determined there is no TODA less than TORA.  The mysterious airport may have incorrect data or the database is incorrect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/airports/airport_safety/airportdata_5010/&quot;&gt;FAA Airport Information&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same database shows that approximately 14% of the runways have an ASDA shorter than TORA.  Multi-engine pilots need to be aware of how their aircrafts performance was created and how to apply the correct declared distances.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-03T01:38:36.180" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24882" PostTypeId="5" CreationDate="2016-02-03T01:58:47.297" Score="0" Body="&lt;p&gt;Declared distances are required for all airports served by Part 121 operations.  There are four declared distances for each runway that correlates to specific aircraft performance calculations.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Takeoff Run Available (TORA) – The runway length declared available and suitable for the ground run of an airplane taking off.&lt;/li&gt;&#xA;&lt;li&gt;Takeoff Distance Available (TODA) – The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.&lt;/li&gt;&#xA;&lt;li&gt;Accelerate−Stop Distance Available (ASDA) – The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.&lt;/li&gt;&#xA;&lt;li&gt;Landing Distance Available (LDA) − The runway length declared available and suitable for a landing airplane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Declared distances can be shorter than the length of the runway when airport runway standards are not sufficient.   The runway elements of Runway Safety Area (RSA), Runway Object Free Area (ROFA), and Runway Protection Zone (RPZ) may reduce a runway’s declared distances to less than the physical length of the runway at geographically constrained airports&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Reference &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/&quot; rel=&quot;nofollow&quot;&gt;FAA AIM 4-3-6&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Aircraft performance can be categorized as balanced or unbalanced for takeoff field length calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For balanced field length performance, the single runway distance number must be lower than both TORA and ASDA values.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For unbalanced field length performance, the accelerate-go distance must be less than TODA and the accelerate-stop distance must be less than TORA.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2016-09-13T14:15:16.850" LastActivityDate="2016-09-13T14:15:16.850" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24883" PostTypeId="4" CreationDate="2016-02-03T01:58:47.297" Score="0" Body="Declared distances are used to determine takeoff and landing performance for aircraft.  It bridges the gap between aircraft performance calculations and runway design criteria." OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2016-09-13T14:15:32.267" LastActivityDate="2016-09-13T14:15:32.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24884" PostTypeId="1" AcceptedAnswerId="24885" CreationDate="2016-02-03T02:01:52.240" Score="11" ViewCount="2797" Body="&lt;p&gt;Here's an image for you to see these little fins. What are they used for?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/501es.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/501es.jpg&quot; alt=&quot;1900&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Air-New-Zealand/Raytheon-1900D/2771398/&amp;amp;sid=13ff59ae4cbebdc9145e127942c637db&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt; (image has been modified to indicate location of fins).&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-04-10T03:07:05.540" LastActivityDate="2019-04-10T03:07:05.540" Title="What are these fins on the Beechcraft 1900?" Tags="&lt;aircraft-design&gt;&lt;beechcraft-1900&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24885" PostTypeId="2" ParentId="24884" CreationDate="2016-02-03T02:48:58.403" Score="8" Body="&lt;p&gt;Well, those fins were put there to increase yaw and pitch stability on the D version because of the change in the centre of gravity due to a higher fuselage from the C version. This D model also had more powerful engines than the C model. To add on, the strakes at the bottom were added for the same reason too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More info can be found &lt;a href=&quot;http://www.pilotspost.co.za/arn0000012&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-02-03T14:03:57.203" LastActivityDate="2016-02-03T14:03:57.203" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24887" PostTypeId="1" CreationDate="2016-02-03T12:06:25.687" Score="11" ViewCount="6314" Body="&lt;p&gt;Is there any special clearance, when military aircraft will overfly other countries' airspace? Are they continuously monitored?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="487" LastEditDate="2016-04-05T23:32:34.033" LastActivityDate="2017-05-22T16:07:42.687" Title="Do military aircraft overflying other countries' airspace require special clearance?" Tags="&lt;military&gt;&lt;airspace&gt;&lt;clearance&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24888" PostTypeId="2" ParentId="24887" CreationDate="2016-02-03T12:34:28.430" Score="6" Body="&lt;p&gt;In switzerland, every aircraft is monitored by the air traffic control. However, if the plane flies without a transponder, it's an unknown aircraft for the ATC-Radar and the military will take the necessary steps to identify the aircraft. Head over &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_traffic_control_radar_beacon_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;here for more details&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the WEF (World economic forum), politicans from all over the world visit Davos. Most of them fly with jets from their airforce. Look at &lt;a href=&quot;https://aviation.stackexchange.com/questions/24653/what-is-this-on-top-of-the-air-force-one&quot;&gt;this&lt;/a&gt; question about the Boeing E-4B Advanced Airborne Command Post 'Nightwatch', carying Ashton Carter to switzerland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.bazl.admin.ch/bazl/en/home/specialists/air-transport/diplomatic-clearances.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Diplomatic Clearances in switzerland&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Foreign state flights over or into Switzerland require special permission, known as diplomatic clearance. This permission is granted by FOCA in consultation with other federal offices.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;State flights include flights engaged in missions undertaken by government, military, customs and police authorities. They particularly include flights by order of the state, flights used for transporting heads of state and high-ranking government officials on official duties, flights used in police and customs operations, and all military flights.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can find more information about this in the link provided. Keep in mind, this applies only to switzerland.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These flights often get intercepted and identified by the swiss air force.&#xA;&lt;a href=&quot;https://twitter.com/HannahThibedeau/status/691019587966623744&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is a video showing two F5E Tiger II intercepting the canadian prime minister as he leaves swiss air space after the WEF 2016&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-03T14:11:01.680" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24889" PostTypeId="2" ParentId="24887" CreationDate="2016-02-03T13:13:14.903" Score="17" Body="&lt;p&gt;In general, a diplomatic clearance is required for overflight of military aircraft over other countries. The aircraft are considered state aircraft and prior clearance has to be obtained through diplomatic channels. Note that the clearance is usually issued by the defence ministry of the concerned country.&lt;/p&gt;&#xA;&lt;p&gt;The mode of clearance and monitoring varies from country to country. In case of US:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Foreign governments seeking diplomatic clearance for state aircraft to transit U.S. territorial airspace or land in the United States must obtain a diplomatic clearance number (DCN) issued in advance by the Office of International Security Operations, Bureau of Political Military Affairs (PM/ISO), Department of State. The DCN authorizes the aircraft to transit or land in the United States and/or its territories, in accordance with the approved itinerary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The overflight permissions are also dependent on agreement between various countries, like &lt;a href=&quot;http://www.stimson.org/research-pages/conditions-for-grant-of-flight-clearance-for-military-aircraft-of-both-countries/&quot; rel=&quot;noreferrer&quot;&gt;India-Pakistan&lt;/a&gt;. In some cases, like some EU countries, &lt;a href=&quot;https://www.eda.europa.eu/info-hub/press-centre/latest-news/2013/06/03/diplomatic-clearances-for-military-transport-aircraft-officially-launched&quot; rel=&quot;noreferrer&quot;&gt;military transport aircraft can operate without diplomatic clearance&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Some other countries, like Canada give &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp11524-chapter3-section2-1132.htm&quot; rel=&quot;noreferrer&quot;&gt;blanket clearance for military aircraft&lt;/a&gt; from some countries:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;3.2.3 Blanket Diplomatic Clearances to Foreign Military Aircraft&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;By order-in-council, United States, United Kingdom, and New Zealand military aircraft are exempted from the requirement to have a formal diplomatic clearance (see 3.2.1 above) prior to overflying and/or landing in Canada.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Military aircraft from North Atlantic Treaty Organization countries other than the United States and the United Kingdom are granted clearances on an annual basis. These clearances do not apply to aircraft carrying armed soldiers, armaments and/or other dangerous goods, nor do they apply to aircraft carrying government personnel.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The procedure is usually the same in most of the countries- the overflight request is given through diplomatic channels to the countries' defence ministry, which then evaluates it and approves (or rejects it). The procedure for Canada is given &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp11524-chapter3-section2-1132.htm&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The state of origin will provide full flight details, as outlined in Annex A, in a diplomatic note from its embassy to Foreign Affairs and International Trade Canada (DFAIT). DFAIT will consult with the Department of National Defence (DND) Operations Centre and, if the foreign military aircraft is landing at a civilian airport, with the Foreign Inspection Division to determine whether any pre-conditions should be imposed. After this consultation, DFAIT will reply to the requesting embassy by a return diplomatic note. On advice from DFAIT, the DND Operations Centre officer will then issue the appropriate flight clearance and distribute copies to the interested parties.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In case of &lt;a href=&quot;http://dgca.nic.in/cars/d3f-f1.pdf&quot; rel=&quot;noreferrer&quot;&gt;India&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;For clearance of flights by foreign military aircraft, the concerned diplomatic mission in India or abroad are required to apply to the Ministry of External Affairs with copy to Air Headquaters/Naval Headquaters forclearance of such flights. After clearance given by Ministry of External Affairs, Air Hqrs/Naval Headquaters will issue necessary AOR number for operation of such aircraft, whether it is overflying Indian air space or landing at any Indian airport (civil or defence).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The monitoring of overflying aircraft depends on the country. Civil ATC usually monitors the aircraft carrying transponders, while the military radars (where available), monitor all air traffic and scramble fighters when the aircraft is not identified/responding properly. Overflight without permission may at the very least result in the &lt;a href=&quot;http://www.dnaindia.com/mumbai/report-us-plane-made-to-land-in-mumbai-gets-iaf-clearance-later-1300264&quot; rel=&quot;noreferrer&quot;&gt;aircraft being forced to land by authorities&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-03T13:13:14.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24890" PostTypeId="1" AcceptedAnswerId="24917" CreationDate="2016-02-03T13:53:29.547" Score="6" ViewCount="800" Body="&lt;p&gt;Before entering on a hold (stack), the ATC should instruct the turns and headings to be accomplished by the crew.  If it is not printed on the charts, as on STARs, what is the correct phraseology to be used by ATC?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="167" LastEditDate="2016-02-03T14:32:18.513" LastActivityDate="2016-02-04T12:25:26.427" Title="What's the correct ATC phraseology to enter a nonpublished hold?" Tags="&lt;phraseology&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24891" PostTypeId="2" ParentId="24890" CreationDate="2016-02-03T14:38:53.470" Score="10" Body="&lt;p&gt;You didn't mention any particular country or jurisdiction, but for the US the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;FAA's ATC orders&lt;/a&gt; say in section 4-6-4:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;PHRASEOLOGY−&lt;/strong&gt;&lt;br&gt;&#xA;   HOLD (direction) OF (fix/waypoint) ON (specified radial, course, bearing, track, airway, azimuth(s), or route.)  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If leg length is specified, &#xA;  (number of minutes/miles) MINUTE/MILE LEG.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If&#xA;  direction of turn is specified, &#xA;  LEFT/RIGHT TURNS.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-02-03T14:38:53.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24892" PostTypeId="1" AcceptedAnswerId="24893" CreationDate="2016-02-03T15:42:38.443" Score="13" ViewCount="5238" Body="&lt;p&gt;The current METAR for Stanstead in the UK says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EGSS 031520Z AUTO 29011KT 9999 FEW021/// //////TCU 07/02 Q1022&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I do not know how to interpret the /// and //////. From what I remember multiple slashes means that data is missing, however the data in this metar seems complete. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What does FEW021/// mean?&lt;/li&gt;&#xA;&lt;li&gt;TCU means Towering Cumulous, which makes sense, but what do the leading ////// mean in this context? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-03T16:11:53.850" Title="What do multiple slashes in METAR mean?" Tags="&lt;weather&gt;&lt;metar&gt;&lt;taf&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24893" PostTypeId="2" ParentId="24892" CreationDate="2016-02-03T15:55:38.857" Score="13" Body="&lt;p&gt;Complete, unless you want to know the height of base of those TCU's!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bulk of the information you're after can be found in &lt;a href=&quot;http://www.ead.eurocontrol.int/pamslight/pdf/4e415453/EG/C/EN/AIP/GEN/EG_GEN_3_5_en&quot;&gt;AIS-GEN 3.5&lt;/a&gt; Section 10.17 - AUTO METAR coding&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In describing the coding used by automated systems, it gives this example&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NNNhhh/// Cloud detected, but it is unknown whether it is a convective cloud type (ie TCU or CB)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And this one&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;//////TCU Towering Cumulus detected, but no information on its height or cloud cover is available&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Which more-or-less covers your two questions, I hope.&lt;/p&gt;&#xA;" OwnerUserId="100" LastActivityDate="2016-02-03T15:55:38.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24894" PostTypeId="1" AcceptedAnswerId="24900" CreationDate="2016-02-03T16:03:15.360" Score="8" ViewCount="909" Body="&lt;p&gt;In a typical situation, where an unknown aircraft appears on radar, and doesn't respond to any radio message, sooner or later fighter aircraft are scrambled to take a closer look. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, can it be reliably determined whether the unknown aircraft in question is a military aircraft or a civilian one, before the pilots of the scrambled jets can take a closer look with their own eyes? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By armed I don't mean deciding whether it carries real missiles or just harmless training dummies, but whether it's a military aircraft or a civilian one. Do we know of cases when this was determined before making visual contact (assuming the UFO didn't respond to any messages)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, is it a fighter jet or a small private business jet? Is it an airliner or a strategic bomber? From how far can you tell the difference?&lt;/p&gt;&#xA;" OwnerUserId="1307" LastEditorUserId="1307" LastEditDate="2016-02-04T14:05:36.543" LastActivityDate="2019-07-09T19:53:24.553" Title="Can it be determined from beyond visual range whether an unknown aircraft is armed or not?" Tags="&lt;military&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24895" PostTypeId="1" CreationDate="2016-02-03T16:08:22.170" Score="11" ViewCount="1657" Body="&lt;p&gt;There are many letters and numbers printed on the vertical stabilizer of US military aircraft. They identify the plane's design and purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are those letters and the meanings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lezP2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lezP2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="19" LastEditDate="2017-05-21T20:45:26.773" LastActivityDate="2017-05-22T18:02:52.200" Title="How to understand US military aircraft designation on the vertical stabilizer?" Tags="&lt;military&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24896" PostTypeId="2" ParentId="24892" CreationDate="2016-02-03T16:11:53.850" Score="5" Body="&lt;p&gt;It means that the report is from an automated weather station and information from sensors are not available for visibility etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.airservicesaustralia.com/aip/current/aip/general.pdf&quot; rel=&quot;noreferrer&quot;&gt;AIP Australia&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;12.20.1 A report from a fully automated AWS that does not include information from sensors for visibility, weather or cloud will report ////, // or ////// respectively in lieu of these parameters.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For this METAR, it can be seen that there are a few clouds at 2100 (with further data missing) and there is towering cumulus, with further data (cloud amount and height missing). For example, decoding this METAR at &lt;a href=&quot;http://www.flightutilities.com/MRonline.aspx&quot; rel=&quot;noreferrer&quot;&gt;flightutilities.com&lt;/a&gt; gives:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Location: EGSS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;LONDON - STANSTED - ENGLAND&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Report emitted the day: 03, time 15:20 UTC&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Wednesday 3 February 2016 20:50 local time.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Report is fully automated, with no human intervention or oversight.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Wind: True direction = 290 degrees, speed: 11 knots (20 km/h) (6 m/s).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Minimum horizontal visibility: 10 km or more.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Clouds: A few (1-2 oktas), at 2100 feet above aerodrome level (640 meters), but it is &lt;strong&gt;unknown whether it is a convective cloud type&lt;/strong&gt;.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Clouds: &lt;strong&gt;cloud type not reported, the cloud base is under the station level or not reported&lt;/strong&gt;, towering cumulus.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Temperature: 7 degrees Celsius (45 Fahrenheit). Dewpoint: 2 degrees Celsius (36 Fahrenheit). Relative humidity 70.47 %. Wind Chill: 4 degrees Celsius (38 Fahrenheit).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;QNH (Sea-level pressure): 1022 hPa (30.18 inches).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(I've removed some data and added emphasis).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-03T16:11:53.850" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24897" PostTypeId="2" ParentId="24895" CreationDate="2016-02-03T17:02:28.090" Score="9" Body="&lt;p&gt;The number on the vertical tail is the aircraft serial number, not the type designation. Here the serial number is AF 41 823. The '4' is the last digit of the finacial year in which money was allocated to manufacture the aircraft and the remaining 4 digits represent the sequence number indicating the sequential order in which the particular aircraft was ordered within that particular financial year.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.joebaugher.com/usaf_serials/usafserials.html&quot;&gt;USAF serials&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Starting on July 1, 1921 (the beginning of FY 1922) a new serial number system was adopted based on procurement within each Fiscal Year. Each serial number now consisted of a base number corresponding to the last two digits of the FY in which money was allocated to manufacture the aircraft, and a sequence number indicating the sequential order in which the particular aircraft was ordered within that particular FY. For example, airplane 22-1 was the first aircraft ordered in FY 1922, 23-1 was the first example ordered in FY 1923, etc. This system is still in use today. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apparently, USAF decided to have five digits in its tail number in 1958. This resulted in the cutting of first digit of the financial year.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Camouflage began to reappear on USAF aircraft during the Vietnam War, and this led to a change in tail number presentation. The letters &quot;AF&quot; were added directly above the last two digits of the fiscal year, followed by the last three digits of the sequence number. The three-digit sequence number has a height of the AF and fiscal year letters combined and is sometimes called the &quot;large&quot; component of the tail number. For example, F-4E serial number 67-0288 had the tail number 67(small) 288 (large). This could of course lead to confusion, since aircraft 67-1288, 67-2288, etc would have exactly the same tail numbers as 67-0288 under this scheme. This would not ordinary cause a whole lot of difficulty unless of course some of these larger serial numbers also happened to be F-4Es (which they were not). Unfortunately, the system was not always consistent--for example F-4D serial number 66-0234 had a tail number that looks like this: 60(small) 234(large).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, '4' represents the second digit of the finacial year, and 1823 gives the sequential number. The aircraft appears to be a &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot;&gt;F-100 Super Sabre&lt;/a&gt;. From &lt;a href=&quot;http://www.f-100.org/hun001.shtml&quot;&gt;f-100.org&lt;/a&gt;, the actual serial number appears to be 54-1862, a F-100C-20-NA model.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-03T17:02:28.090" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24898" PostTypeId="2" ParentId="24894" CreationDate="2016-02-03T17:10:52.237" Score="5" Body="&lt;p&gt;No, this is not possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine, FedEx flying a plane into Russia with FedEx parcels on it. A week later, &lt;em&gt;the exact same&lt;/em&gt; plane, now hired by the US Army enters Russian airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last week, it was a civilian plane, this week, it is a military plane. The only difference is who pays the bill. How is radar going to know who pays the bill?&lt;/p&gt;&#xA;" OwnerUserId="3721" LastActivityDate="2016-02-03T17:10:52.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24899" PostTypeId="1" AcceptedAnswerId="24901" CreationDate="2016-02-03T17:41:58.437" Score="12" ViewCount="14544" Body="&lt;p&gt;What is the difference between azimuth and heading?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand heading, track, radial, course and bearing but I don't know what azimuth is. I rarely hear it used. The Wikipedia definition is &lt;em&gt;a horizontal angle measured clockwise from a north base line or meridian.&lt;/em&gt; How does that differ from heading?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Bonus question: when atc tells you there's a plane at your 2 o'clock, is there a word for that?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="13197" LastEditDate="2016-04-25T10:29:52.313" LastActivityDate="2019-01-29T19:15:47.213" Title="What is the difference between azimuth and heading?" Tags="&lt;terminology&gt;&lt;heading&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24900" PostTypeId="2" ParentId="24894" CreationDate="2016-02-03T18:00:33.633" Score="10" Body="&lt;p&gt;Only if the airplane wants you to know it is armed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It has several ways at its discretion:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If it has a powerful radar, it can switch it on at altitude and announce its presence to other aircraft up to 150 km away. &lt;/li&gt;&#xA;&lt;li&gt;It can send &lt;a href=&quot;https://en.wikipedia.org/wiki/Identification_friend_or_foe&quot;&gt;IFF&lt;/a&gt; squawks which are reserved for military aircraft. Note that IFF is used by both military and &lt;a href=&quot;https://en.wikipedia.org/wiki/Iran_Air_Flight_655&quot;&gt;civilian aircraft&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Both methods are only indirectly indicating whether an aircraft is armed. The armament itself will not show up at BVR distances. In the end, if you want to be sure, you have to move some sensors close to the aircraft if the weapons are carried externally, or even wait until they are deployed when they are carried internally. Especially many small aircraft are used both in a civilian and a military role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A BVR radar is a dead giveaway for a military aircraft - such equipment is not fitted with civilian aircraft, and removed or disabled when an ex-military aircraft is converted to civilian use. Similarly, supersonic speed, which can reliably be detected with Doppler radars, is a telltale sign of military aircraft approaching.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transport aircraft are much harder to distinguish from bombers on the basis of radar signals alone, and in the end you cannot exclude that the hostile aircraft tries to spoof your equipment into classifying it as a civilian aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-03T22:30:18.860" LastActivityDate="2016-02-03T22:30:18.860" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24901" PostTypeId="2" ParentId="24899" CreationDate="2016-02-03T18:43:37.680" Score="9" Body="&lt;p&gt;A &lt;strong&gt;heading&lt;/strong&gt; (in the general case of moving &quot;forward&quot;) is the direction your nose is pointed in. This may not be your &lt;em&gt;course&lt;/em&gt; (&lt;a href=&quot;https://aviation.stackexchange.com/q/8000/1467&quot;&gt;as discussed here&lt;/a&gt;).&lt;br&gt;&#xA;Headings are measured from onboard a traveling vehicle or object (e.g. from the cockpit of an aircraft or the bridge of a ship at sea).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An &lt;strong&gt;azimuth&lt;/strong&gt; is a bearing, more precisely a &lt;em&gt;compass bearing&lt;/em&gt; from a specific point of observation like a radar station. (The &quot;North&quot; used as a reference may be either magnetic or true depending on the system you're working with, but for purposes of this discussion it doesn't matter.)&lt;br&gt;&#xA;Often the point of observation is fixed (ground radar, a control tower, an artillery spotter, etc.), though it need not be as long as the observation can be mapped to a compass bearing somehow. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bonus Answer&lt;/strong&gt;: The &quot;O'Clock&quot; positions are an informal type of &lt;em&gt;relative bearing&lt;/em&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/24899/difference-between-azimuth-and-heading/24901#comment58493_24899&quot;&gt;as mins noted&lt;/a&gt;: The 360-degree circle is broken up into 12 chunks (30 degrees each) for easier scanning, with &quot;12 O'Clock&quot; being directly in front of you and &quot;6 O'Clock&quot; directly behind.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An important caveat to be aware of is that when ATC provides a &quot;clock bearing&quot; for traffic it's relative to the aircraft's &lt;em&gt;course&lt;/em&gt; (12 O'Clock is aligned with the aircraft's track over the ground as shown on the radar). Depending on wind there may be considerable variation between your &lt;em&gt;course&lt;/em&gt; (direction of travel) and your &lt;em&gt;heading&lt;/em&gt; (direction the nose is pointing), so the called traffic may appear in a different location when you look out your window.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-03T19:32:23.620" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24902" PostTypeId="2" ParentId="24894" CreationDate="2016-02-03T18:54:11.980" Score="4" Body="&lt;p&gt;The only system designed to do this (other than the radars that Jörg mentioned that try to identify radar signatures) is &lt;a href=&quot;https://en.wikipedia.org/wiki/Identification_friend_or_foe&quot; rel=&quot;nofollow&quot;&gt;IFF&lt;/a&gt;, which stands for Identification Friend or Foe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system was developed during WWII and has gone through a number of refinements. The identification is determined from the mode in which the transponder replies to interrogation. Modes 1, 2, 4 and 5 are designated for military use only. 4 and 5 are used by NATO forces. Modes A, C and S can be used for military or civilian.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system has a lot of holes in it, though. It depends on cooperation from the aircraft to squawk the correct mode to identify itself as military. If they squawk mode A, C and S or don't squawk at all then you don't know anything for certain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The system was part of the problem in the shootdown of &lt;a href=&quot;https://en.wikipedia.org/wiki/Iran_Air_Flight_655&quot; rel=&quot;nofollow&quot;&gt;Iran Air flight 655&lt;/a&gt;. A mistake made by the radar operator caused him to misidentify the airliner as an Iranian fighter plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes even visual contact doesn't help. &lt;a href=&quot;https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007&quot; rel=&quot;nofollow&quot;&gt;Korean Air flight 007&lt;/a&gt;, a 747 was visually mistaken for a military RC-135 by a Soviet pilot and shot down. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-02-03T18:54:11.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24903" PostTypeId="1" AcceptedAnswerId="24913" CreationDate="2016-02-03T19:57:51.977" Score="6" ViewCount="613" Body="&lt;p&gt;As can be seen on &lt;a href=&quot;https://aviation.stackexchange.com/q/24040/8730&quot;&gt;this question&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/22128/8730&quot;&gt;this question&lt;/a&gt; the OJC VOR has been decommissioned but the DME is still active. What would be the purpose in having DME without VOR?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-04T11:47:07.793" Title="Why would a VOR be decommissioned leaving the DME?" Tags="&lt;vor&gt;&lt;navaids&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24905" PostTypeId="1" AcceptedAnswerId="24907" CreationDate="2016-02-04T02:03:30.607" Score="2" ViewCount="357" Body="&lt;p&gt;Is it possible to find out the name of the Captain on a previous flight?&lt;/p&gt;&#xA;" OwnerUserId="13314" LastActivityDate="2016-02-04T03:40:50.910" Title="Obtaining Captain's name on historical flights?" Tags="&lt;pilots&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2016-02-04T13:20:41.153" ContentLicense="CC BY-SA 3.0" />
  <row Id="24906" PostTypeId="1" AcceptedAnswerId="24911" CreationDate="2016-02-04T03:24:10.893" Score="18" ViewCount="2787" Body="&lt;p&gt;A personal (pipe) dream of mine is to own a new aircraft, but the costs for certified GA aircraft is borderline outrageous. A new Cessna 172, considered an entry level aircraft, can go for well over \$250,000 new. The Icon A5, an entry level light sport goes for about \$190,000 &lt;strong&gt;for the base model&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not discounting the engineering process or tooling required, but what really keeps the price of these aircraft so high? Is it possible that a company could bring an aircraft to market that is comparable to the A5 below the \$100,000 mark? I find it hard to imagine that a company couldn't take an aircraft like the SeaRey, certify it, and get it out for a reasonable price. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, what are the factors that make certified GA aircraft so expensive, especially for established companies like Cessna, Piper, or others? Does the mere presence of an FAA certification command a premium price? &lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2019-08-13T14:37:32.777" Title="What keeps certified GA aircraft from being affordable?" Tags="&lt;aircraft-design&gt;&lt;usa&gt;&lt;cost&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24907" PostTypeId="2" ParentId="24905" CreationDate="2016-02-04T03:40:50.910" Score="5" Body="&lt;p&gt;Generally, no.  As a matter of protecting employees' privacy, that sort of information isn't typically made available beyond what a passenger may notice (nametags) or remember from a PA (&quot;This is Captain Smith...&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an unusual situation, it might be possible to get a name by contacting the airline, but it's probably unlikely that you'd get an answer back unless the pilot happened to call or write back to you.  Which could happen, but not often.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-02-04T03:40:50.910" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24908" PostTypeId="2" ParentId="24894" CreationDate="2016-02-04T03:55:58.873" Score="4" Body="&lt;p&gt;There &lt;em&gt;&lt;strong&gt;are&lt;/strong&gt;&lt;/em&gt; methods beyond the IFF itself, although what's available publicly isn't all that comprehensive.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://rads.stackoverflow.com/amzn/click/com/1849196850&quot; rel=&quot;nofollow noreferrer&quot; rel=&quot;nofollow noreferrer&quot;&gt;This book on Amazon&lt;/a&gt; is a start; &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar_MASINT#Non-Cooperative_Target_Recognition&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Wikipedia article&lt;/a&gt; goes into more depth:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Radar offers the potential of non-cooperative target recognition (NCTR). These techniques, which could work if IFF systems fail, have been especially secret. No one has yet proposed, however, NCTR that will be effective if a coalition partner is flying the same aircraft type as the enemy, as in Desert Storm. IFF, presumably with encryption, probably is the only answer to that problem.&lt;/p&gt;&#xA;&lt;p&gt;One open-literature study combined several pieces of radar information: cross-section, range, and Doppler measurements.[22] A 1997 Defense Department report mentions &amp;quot;Air Force and Navy combat identification efforts focus on noncooperative target recognition technologies, including inverse synthetic aperture radar imaging, jet engine modulation (JEM), and unintentional modulation on pulse-based specific emitters&amp;quot;.[23]&lt;/p&gt;&#xA;&lt;p&gt;NCTR on JEM specifically depends on the periodic rotation of the blades of a turbine, with variations caused by the geometry of the elements of the engine (e.g., multiple rotors, the cowling, exhaust, and stators). More generally, the idea of &amp;quot;micro-Doppler&amp;quot; mechanisms, from any mechanical movements in the target structure (&amp;quot;micro-motion dynamics&amp;quot;), extends the problem to cover more than rotating aircraft structures, but also automatic gait recognition of human beings.[24] The micro-Doppler idea is more general than those used in JEM alone to consider objects that have vibrational or other kinds of mechanical movement. The basisc of JEM is described in .[25][26] One non-rotational effect would be the surface vibrations of a ground vehicle, caused by the engine, which would be different for gas turbines of tanks and diesel engines of trucks. ISAR is especially useful for NCTR, since it can provide a two-dimensional map of the micromovements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-04T03:55:58.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24910" PostTypeId="2" ParentId="19217" CreationDate="2016-02-04T04:17:32.010" Score="6" Body="&lt;p&gt;I've been using myflightbook.com for a couple of years now.  It is free, easy to use, and very comprehensive.  I've flown over 100 different aircraft types and am rated in several different categories so it's important to me that the elogbook that I use is capable of handling all of the oddball piloting stuff that I do and myflightbook does it all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As to the question about endorsements.  The FAA does allow for electronic signatures as one of the previous posters correctly pointed out (AC 120-78) and myflightbook supports this feature which is a good way to collect endorsements for &quot;dual received&quot; flights.  With respect to endorsements that give a pilot an operating privilege, such as high-performance or a flight review, you can have the instructor write it out on paper and then snap a pic of it with your smartphone.  Then just attach or upload the pic to your elogbook. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last time I needed an R44 SFAR flight review the instructor asked for my logbook and I just slid him a piece of scratch paper and snapped the pic.  Myflighbook allowed me to quickly type in the flight entry and attach the pic.  I've also had to show a part 121 carrier that I was going to work for my logbook and they were fine with a printout from my elogbook.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope that helps answer the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regards,&#xA;  Alan Brown&#xA;  ATP: ASEL, AMEL, LR-Jet, SA-2000&#xA;  Commercial: Helicopter, Glider, ASES&#xA;  CFI: ASE, AME, IA, Glider&lt;/p&gt;&#xA;" OwnerUserId="13337" LastActivityDate="2016-02-04T04:17:32.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24911" PostTypeId="2" ParentId="24906" CreationDate="2016-02-04T07:24:20.760" Score="22" Body="&lt;p&gt;Low volume, high liability, and the overhead of certification all contribute to the high price of factory-new aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Certification&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The process to design, build, and test an aircraft to receive a type certificate from the FAA adds time and cost to any new clean-sheet design (substantially more cost if the design is novel in some way).&lt;br&gt;&#xA;The design and construction techniques must conform to the requirements in the FARs, and you have to demonstrate conformance to FAA inspectors (who will also want to see you assemble a few planes under their oversight before issuing you a production certificate to go ahead and make them on your own).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Volume&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;50+ year old designs like the Piper PA-28 and Cessna 172 that are still in production on an approved type certificate avoid that cost, but are still a low-volume high-touch product: &lt;a href=&quot;https://www.youtube.com/watch?v=6uXrXX-gouo&quot; rel=&quot;noreferrer&quot;&gt;Here's a wing being assembled&lt;/a&gt;.&lt;br&gt;&#xA;Because of the relatively low demand (and thus low sales volume) the cost of the skilled personnel to build aircraft isn't spread out the way it is with cars (and the investment in large-scale low-touch automation isn't economically feasible). That drives up the manufacturing cost, and the price goes up with it to ensure the manufacturer is still making a profit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar economies of scale affect all the third-party parts going into new planes as well: radios, instruments, lights, etc. that conform to applicable FAA Technical Standard Orders (TSOs) are rather expensive.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Liability&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Finally, any new aircraft starts a new 18-year liability period for the manufacturer. Any accident that results in whole or in part from manufacturer errors, omissions, or negligence in a new aircraft can come back to haunt that manufacturer in the form of a lawsuit, so the cost of product liability insurance is baked into the price of every new aircraft. (After 18 years the manufacturer is off the hook thanks to the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Aviation_Revitalization_Act&quot; rel=&quot;noreferrer&quot;&gt;General Aviation Revitalization Act&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these factors take the Searey from being a \$50,000 kit (airframe, engine, and propeller) to a \$150,000 factory-built Light Sport aircraft, and that is putting it on the market as a &lt;em&gt;Light Sport&lt;/em&gt; aircraft under &quot;consensus industry standards&quot;. Producing it as a Part 23 certificated aircraft would add the additional cost and requirements of FAA certification.&lt;br&gt;&#xA;(I'm using the Searey as a convenient example since you mentioned it in your question and I could find kit and factory-built pricing easily, but other light sport aircraft available in both kit and factory models seem to stack up similarly. I don't know of any that have been subsequently &quot;upgraded&quot; to a Part 23 aircraft: Only a few manufacturers have successfully launched that sort of product, and those command rather substantial prices on the new market.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-02-06T01:14:17.077" LastActivityDate="2016-02-06T01:14:17.077" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="24913" PostTypeId="2" ParentId="24903" CreationDate="2016-02-04T11:47:07.793" Score="11" Body="&lt;p&gt;Many older Air Transport Airplanes have no GPS. I'm a pilot since 1970. I operated A330 for 5 years until 2000 without GPS. The average IRS position (Inertial Reference Systems) in the FMS was updated by DME/DME. On older airplanes we selected the DME Stations manually preferably with a 90 degree cut-angle to obtain an accurate update. A single VOR/DME station could be used for update as well but it's a lot less accurate. Example, if you are 60 NM away from a VOR, a 1° error in azimuth would cause an error of about 1 NM. All Airbus aircraft have an approval for RNAV Approaches down to an accuracy of 0,3 NM with 2 DME stations available. This is why DME's are still useful, many ILS have a DME. Conventional VORs are terribly inaccurate, Doppler VORs are much better even down to a lower altitude, but requires more space.&lt;/p&gt;&#xA;" OwnerUserId="13341" LastActivityDate="2016-02-04T11:47:07.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24914" PostTypeId="1" CreationDate="2016-02-04T11:51:54.813" Score="10" ViewCount="2404" Body="&lt;p&gt;What is the reason behind this unusual nose shape? I am not referring only to the presence of the protuberance on the tip, but mainly to the asymmetry between the top and bottom side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iKRR9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iKRR9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Tupolev_Tu-22M3_Backfire-C_33_red_%289851688475%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be seen better in the profile depiction here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lRji1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lRji1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.airvectors.net/avtu22.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="487" LastEditDate="2016-02-07T18:42:12.010" LastActivityDate="2016-02-08T01:12:30.147" Title="Why does the Tu-22M3 nose have this peculiar shape?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;tupolev&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24915" PostTypeId="2" ParentId="24914" CreationDate="2016-02-04T12:16:59.203" Score="3" Body="&lt;p&gt;The Tu-22M3's nose houses a Leninets PN-AD radar and a NK-45 navigation and attack system. The NK-45 provides improved low-altitude flight, compared to earlier models.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several Tu-22M3's were converted to Tu-22M3R who carry a &lt;a href=&quot;https://en.wikipedia.org/wiki/Side_looking_airborne_radar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shompol side looking airborne radar&lt;/a&gt; and other &lt;a href=&quot;https://en.wikipedia.org/wiki/Signals_intelligence#Electronic_signals_intelligence&quot; rel=&quot;nofollow noreferrer&quot;&gt;Electronic signals intelligence equipment&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this equipement is stored in the nose of the aircraft. This explains the strange appearance (The asymmetry between the top and bottom).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*Edit:&#xA;I can only &lt;strong&gt;guess&lt;/strong&gt; &lt;em&gt;why&lt;/em&gt; the nose is asymmetric: Maybe some parts of the equipment located in the nose has to lock forward / down of the plane. The asymmetric bottom may provide a better &quot;view&quot; for the equipment. (See my comment below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On this image, you can see all the equipment in the nose. Unfortunately the quality is too poor to be able to read the caption.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/acZdR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/acZdR.jpg&quot; alt=&quot;Tu-23M3 Blueprint&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://s-media-cache-ak0.pinimg.com/736x/9b/90/05/9b900565de671429a0f364bcacf01c13.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tu-22M &lt;strong&gt;had&lt;/strong&gt; a retractable probe on the top for aerial refueling:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8bap9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8bap9.jpg&quot; alt=&quot;Tu-22M nose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Strategic_Arms_Limitation_Talks&quot; rel=&quot;nofollow noreferrer&quot;&gt;salt&lt;/a&gt; negotations, the probe was removed but it &lt;a href=&quot;https://web.archive.org/web/20120305082952/http://www.vectorsite.net/avtu22.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;could be reinstalled.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;because with refueling it was considered an intercontinental range strategic bomber.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0710607059&quot; rel=&quot;nofollow noreferrer&quot;&gt;Janes-All-Worlds-Aircraft-1980-81&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the Soviets secretly agreed to reduce Tu-22M production to thirty aircraft per year and not to give them an intercontinental range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Strategic_Arms_Limitation_Talks#SALT_II&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stratetic Arms Limitation Talks 2&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-22M&quot; rel=&quot;nofollow noreferrer&quot;&gt;Overall Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="9544" LastEditDate="2016-02-04T13:46:37.033" LastActivityDate="2016-02-04T13:46:37.033" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24916" PostTypeId="2" ParentId="24899" CreationDate="2016-02-04T12:21:06.427" Score="1" Body="&lt;p&gt;As already explained in &lt;a href=&quot;https://aviation.stackexchange.com/a/24901/753&quot;&gt;voretaq7's answer&lt;/a&gt;, the true heading is the direction in which the nose of the aircraft points during a flight when measured in degrees clockwise from true north. Now consider you would see a star right ahead of you on the sky, the the azimuth of this star is identical to your true heading. Another example, if the star is 30 degrees to your right  on the sky and your true heading is 90° the azimuth of the star is 120°. The reference of the azimuth is True north in this case. The term azimuth is used in Astronavigation and when it comes to the use of navigation charts. &lt;/p&gt;&#xA;" OwnerUserId="13341" LastEditorUserId="753" LastEditDate="2016-02-05T14:58:16.253" LastActivityDate="2016-02-05T14:58:16.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24917" PostTypeId="2" ParentId="24890" CreationDate="2016-02-04T12:25:26.427" Score="2" Body="&lt;p&gt;In the US e.g. ATC will say &quot; hold east of Miami VOR&quot;, meaning you hold on Radial 090 right turns, 1 minute leg. In most of the rest of the wold ATC will give you the inbound course unless stated on the chart.&lt;/p&gt;&#xA;" OwnerUserId="13341" LastActivityDate="2016-02-04T12:25:26.427" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24918" PostTypeId="1" AcceptedAnswerId="24933" CreationDate="2016-02-04T12:47:49.087" Score="7" ViewCount="540" Body="&lt;p&gt;I saw a METAR for a nearby airport that had A2248 ... SLPNO in it with no maintenance indicator.  Is the SLPNO a sign that the altimeter setting in the METAR is untrustworthy as well?  How else does one get the altimeter setting (assuming ATIS is drawing from the same, messed up data source that the METAR is -- this is an RMK AO2A METAR), or is one grounded until the AWOS reading is fixed?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="487" LastEditDate="2016-02-05T03:00:50.163" LastActivityDate="2016-02-05T12:56:04.523" Title="What does one do when the weather report has a bogus altimeter setting?" Tags="&lt;weather&gt;&lt;altimeter&gt;&lt;metar&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="24919" PostTypeId="1" AcceptedAnswerId="24922" CreationDate="2016-02-04T15:22:57.920" Score="5" ViewCount="2279" Body="&lt;p&gt;Why is the pitch measured with respect to the horizon and not the ground? How different are the angles between the ground and the horizon? Would it be possible to fly with an attitude indicator that indicated pitch with respect to ground rather than horizon? What does it mean when you have a 0 degree pitch with respect to the horizon? What, exactly, are you flying towards in that case?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always had a hard time understanding this. Thanks for your time.&lt;/p&gt;&#xA;" OwnerUserId="13346" LastActivityDate="2016-02-04T21:31:44.707" Title="Why is pitch measured with respect to the horizon and not the ground?" Tags="&lt;pitch&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24920" PostTypeId="2" ParentId="24919" CreationDate="2016-02-04T15:39:53.197" Score="3" Body="&lt;p&gt;An airplane needs to be oriented to a frame of reference which does not change depending on altitude or the elevation of the ground, this is so the pilot will be able to judge the angle of the wing through the air flow. If you used angle between the ground and the horizon then it would be constantly changing depending on your height and the elevation of the ground. If the ground level ahead goes up then the angle between ground and horizon decreases, if the ground level stays the same and you increase altitude the angle increases. If you see the angle diminish you would not know whether it was because of a change in attitude, altitude, or ground elevation. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-04T15:39:53.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24921" PostTypeId="2" ParentId="24919" CreationDate="2016-02-04T15:43:37.873" Score="1" Body="&lt;p&gt;The &quot;horizon&quot; is a fixed reference that will be the same wherever you are flying. It is fairly straightforward to create an instrument for the cockpit that illustrates pitch and roll with respect to this horizon. It also relates to gravity, since gravity will be pointing straight down with respect to the horizon. Pitching up means you are working against gravity, regardless of what the ground below you is like. Humans have a natural sense of &quot;up&quot; and what is &quot;level&quot;, which is based on our perception of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Showing pitch with respect to the ground would be much more chaotic. You would need some way to know what the ground below the aircraft is doing, at any altitude. The relationship of &lt;a href=&quot;https://aviation.stackexchange.com/q/2980/1696&quot;&gt;pitch and power&lt;/a&gt; would be even more confusing, as pitch would no longer consistently relate to gravity, and therefore no longer consistently relate to power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers typically like a smooth and level flight. Airliners flying over mountains would have a wildly changing pitch indication, despite flying &quot;straight and level.&quot; If an aircraft wanted to fly level with respect to the ground, it would require steep climbs and descents in these areas. Since air density changes with height above sea level, not the ground, the &lt;a href=&quot;https://aviation.stackexchange.com/q/11217/1696&quot;&gt;aircraft's performance&lt;/a&gt; would continually change as it stays level with the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot is concerned about hitting the ground, there are &lt;a href=&quot;https://aviation.stackexchange.com/q/22052/1696&quot;&gt;many better ways to avoid that&lt;/a&gt;. Traditionally, charts and navigation will allow a pilot to avoid terrain. Technology like &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar_altimeter&quot; rel=&quot;nofollow noreferrer&quot;&gt;radar altimeters&lt;/a&gt; have also helped, which shows the pilot how high they are above the ground. Newer systems allow things like &lt;a href=&quot;https://en.wikipedia.org/wiki/Synthetic_vision_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;synthetic vision&lt;/a&gt; if the terrain is not clearly visible.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-02-04T15:54:50.933" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24922" PostTypeId="2" ParentId="24919" CreationDate="2016-02-04T15:52:43.633" Score="14" Body="&lt;p&gt;Pitch is measured with respect to a plane orthogonal to the local weight¹ force, which is properly called the horizon&lt;strong&gt;tal&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is used because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is equipotential plane of the gravitational field. Moving around it won't change your potential energy.&lt;/li&gt;&#xA;&lt;li&gt;Is always well defined.&lt;/li&gt;&#xA;&lt;li&gt;Is smooth and locally flat (it is still a spherical surface globally, of course).&lt;/li&gt;&#xA;&lt;li&gt;Can be measured by averaging inertial forces on board without external reference.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is called simply horizon, presumably because looking at the horizon is the easiest way to find that plane by human senses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using ground, which is not flat, as reference wouldn't work. Aircraft need to fly mostly along the equipotential plane, because climbing to a higher one requires adding more energy by the engines and descending below means the aircraft accelerates and needs to dissipate (= waste) the energy. So following terrain would require quite a bit more energy than flying horizontal. Plus it would be very complicated.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ By weight I mean the sum of gravity and centrifugal force in the reference frame rotating with &lt;em&gt;Earth&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-02-04T21:31:44.707" LastActivityDate="2016-02-04T21:31:44.707" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="24923" PostTypeId="2" ParentId="24427" CreationDate="2016-02-04T15:54:12.430" Score="11" Body="&lt;p&gt;As you have already imagined, it's the APU fuel line shroud drain, as visible here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tGkdn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tGkdn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://www.flickr.com/photos/21746387@N06/14516248098&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Detail:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zSZa0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zSZa0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fin gives an aerodynamic profile to the drain. The reason this drain exists seems to be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Natural fuel leaks from the auxiliary power unit (APU) fueling line&#xA;  were supposed to drain harmlessly out the bottom of the structure as&#xA;  designed, though rather than do that, the fuel was pooling into the&#xA;  APU exhaust cone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.think-dash.com/2011/06/apu-drainage-behind-boeings-787-tail.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-02-04T15:54:12.430" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24924" PostTypeId="2" ParentId="24919" CreationDate="2016-02-04T16:21:58.303" Score="3" Body="&lt;p&gt;Your question seems to boil down to the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that the earth is a perfect sphere, why does the virtual horizon (i.e., the pitch indicator) point to the horizon? The answer is, &lt;strong&gt;it doesn't&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pitch is determined with gravity, which always 'points' to the center of the earth. The virtual horizon you see on your pitch indicator is always at an angle of 90° (i.e., a straight angle) from that, and only points to the actual horizon in case you were exactly on the ground. &lt;strong&gt;This difference is negligible for normal flight (which happens in the very lowest part of the atmosphere). The following is only to demonstrate what is actually happening.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dNm2j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dNm2j.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the above picture, I drew an exaggerated version of what you mean. The red line points to the center of the earth (so, where gravity points), and is the reference of your pitch indicator. The green line is what you will see on your pitch indicator. The blue line is where you actually see the horizon. They don't match up, and &lt;strong&gt;that's fine&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot really doesn't care where the horizon is. He cares about maintaining altitude, ascending or descending. Maintaining altitude is done by keeping the airplane level with respect to the center of the Earth, in which case he will make a complete circle around the earth since his velocity vector is always perpendicular to the center of the Earth. Ascending and descending is done by having the pitch above or below this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the picture you can see that if the virtual horizon were to point to the actual horizon, you would eventually impact the ground - on a perfectly smooth sphere, it would be a smooth landing too. I guess there's a reason they call it the virtual horizon, eh?&lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2016-02-04T16:21:58.303" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24925" PostTypeId="2" ParentId="24869" CreationDate="2016-02-04T18:06:36.353" Score="5" Body="&lt;p&gt;If you come up blank on the various open sources that have been suggested, which wouldn't surprise me, your best bet may be a personal letter to Air Canada and another as well to whatever headquarters address you can find for Jazz, explaining what you are attempting to do, and asking if they'd be willing to look up the aircraft ID for those flights for you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the right person, it's probably about 2 minutes of work total to look them up, although getting the request TO that person may take considerably longer.  Many airlines have customer relations departments whose job it is to address &lt;strong&gt;&lt;em&gt;whatever&lt;/em&gt;&lt;/strong&gt; issues people write in about, and a pleasant &quot;we flew with you, flight was great, love you guys, silly us, forgot to get the tail #, baby's logbook, dedicated customers, please help, really love you guys, thanks millions...&quot; letter may well get pointed to the right department and get you an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could also try calling and/or e-mailing; you're actually NOT looking for the standard front-line Reservations agent or &quot;let me help you with your flight&quot; type of person, but rather somebody in the Dispatch or Maintenance records section, as those are the people who have the big database of everything that the airline has ever done.  That said, it may be difficult to get past the usual barriers that airlines have in place to keep worried passengers in an airport from trying to talk to dispatchers about &quot;why isn't my flight here yet???&quot;  So I'd expect that the pleasant letter to a Customer Relations department may be your best bet.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-02-04T18:06:36.353" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24926" PostTypeId="1" AcceptedAnswerId="24927" CreationDate="2016-02-04T18:14:53.583" Score="18" ViewCount="4433" Body="&lt;p&gt;Learning to fly in general aviation in the west since the mid 2000s I'm used to the common attitude indicators like this one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/ZfnDNtC.png&quot; alt=&quot;attitude indicator&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also seen older ones that are black and white as well as many varieties of attitude indicator display arrangements in glass panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question deals with other ways of displaying this information. I've heard pilots talk about how some eastern airplanes have very different ways of presenting pilots with attitude information. What approaches are out there? What do they look like and where are they found?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2019-05-05T02:49:06.767" Title="What types of attitude indicators are there?" Tags="&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24927" PostTypeId="2" ParentId="24926" CreationDate="2016-02-04T18:28:16.897" Score="23" Body="&lt;p&gt;Russian-made aircraft have attitude indicators that work exactly opposite of western ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/BoBzN.jpg&quot; alt=&quot;attitude indicators&quot;&gt;&#xA;&lt;a href=&quot;http://forum.worldofwarplanes.com/index.php?/topic/18184-counter-intuitive-attitude-indicator/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;with the western style, on the left, the virtual airplane figure is fixed so it's always upright to the pilot and the horizon moves. On the Russian style AI the horizon is fixed so it is level from the pilots POV and the aircraft symbol moves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just two ways of looking at it, but if you're used to one the other can be confusing.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-02-04T18:28:16.897" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="24928" PostTypeId="2" ParentId="24918" CreationDate="2016-02-04T18:54:47.553" Score="2" Body="&lt;p&gt;If on the ground set your altimeter to indicate the field elevation and the altimeter pressure indicator will be adjusted with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If in the air ask a controller for it.  Most towers I have been in have their own air pressure indicators so that they can advise pilots of the correct altimeter setting for landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If uncontrolled ask the airport &quot;radio&quot; for it.  &quot;Radio&quot;is a term used for anyone monitoring.&lt;/p&gt;&#xA;" OwnerUserId="13293" LastEditorUserId="100" LastEditDate="2016-02-05T12:56:04.523" LastActivityDate="2016-02-05T12:56:04.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24929" PostTypeId="1" AcceptedAnswerId="24931" CreationDate="2016-02-04T21:44:46.670" Score="5" ViewCount="1654" Body="&lt;p&gt;&lt;strong&gt;Effects of Power Extraction on Turbofan Compressor and Turbine Maps&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two diagrams below show the effects of shaft power extraction (&lt;em&gt;shaft power offtake&lt;/em&gt; / &lt;em&gt;shaft power off-take&lt;/em&gt; for the propulsion of accessories such as fuel-/hydraulic-/oil-pumps, generators etc.) on a high-bypass turbofan engine at a flight altitude of $H = 11km$ and a speed of $Ma = 0.8$, calculated with &lt;a href=&quot;http://www.gasturb.de/&quot; rel=&quot;nofollow noreferrer&quot;&gt;GasTurb 12&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FMnAg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FMnAg.png&quot; alt=&quot;Effects of Power Extraction on Turbofan Compressor and Turbine Maps&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Effects of Power Extraction on the Operating Line (Blue)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why are the operating lines (blue) of both the compressor and turbine shifted to the left towards the surge line?&lt;/li&gt;&#xA;&lt;li&gt;In particular, why does the non-dimensional corrected mass flow decrease, while the pressure ratio stays approximately constant?  &lt;/li&gt;&#xA;&lt;li&gt;The same question from a different angle: Why does the pressure ratio not decrease at a constant mass flow?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="19" LastEditorDisplayName="user12485" LastEditDate="2016-07-11T08:40:55.337" LastActivityDate="2016-07-11T08:40:55.337" Title="What is the effect of power extraction on turbofan compressor and turbine maps?" Tags="&lt;aerodynamics&gt;&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24930" PostTypeId="2" ParentId="24926" CreationDate="2016-02-04T22:38:01.333" Score="15" Body="&lt;p&gt;There's also the 3D attitude indicator from old fighter planes.&lt;a href=&quot;https://i.stack.imgur.com/vjpBp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vjpBp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-02-04T22:38:01.333" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24931" PostTypeId="2" ParentId="24929" CreationDate="2016-02-04T23:40:10.163" Score="0" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/Off-Takes/Off-Takes_PUB_AST-CD-Version_13-04-23.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Scholz, D. et al.: &amp;quot;Fuel Consumption due to Shaft Power Off-Takes from the Engine&amp;quot;, AST 2013 - Workshop on Aircraft System Technologies, 23-24 April 2013, Hamburg, Germany&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Shaft power extraction&lt;/strong&gt;, no matter if taken from the High-Pressure (HP) shaft or the Low-Pressure (LP) shaft, &lt;strong&gt;will reduce the speed of this shaft. This reduces the mass flow&lt;/strong&gt; [...] &lt;strong&gt;and the thrust&lt;/strong&gt; [...]&lt;strong&gt;. Constant thrust regulation applied to the engine&lt;/strong&gt; (achieved today by the Full Authority Digital Engine Control, FADEC) &lt;strong&gt;will primarily result in an increase of fuel flow, increasing the Turbine Entry Temperature, TET. Higher pressure in the combustion chamber and higher turbine load together with a reduced shaft speed will enlarge the angle of attack at the compressor blades and therewith slightly lift the pressure rise achieved at each stage. In this way, shaft power off-takes also result in closer operation to the surge line.&lt;/strong&gt; [...]&lt;br /&gt;&#xA;If shaft power is taken from the LP shaft, its speed will reduce. Also, the fan speed is reduced, which decreases the thrust considerably. With the engine controls increasing the TET, the HP shaft (in this case not affected by power off-takes) will even increase its speed and mass flow through the LP turbine and compressor compared to the original situation. [...]&lt;br /&gt;&#xA;If shaft power is taken from the HP shaft, its speed will reduce and so also the mass flow through the LP compressor and turbine. With the engine controls increasing the TET, the situation is rectified.&lt;br /&gt;&#xA;Low thrust ratings always mean a high relative power extraction P/T [shaft power off-take P, jet engine thrust T] and high relative specific fuel consumption. At high thrust ratings, the relative power extraction P/T is smaller and the relative specific fuel consumption is less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerDisplayName="user12485" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-04T23:40:10.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24932" PostTypeId="1" CreationDate="2016-02-05T01:15:11.980" Score="5" ViewCount="209" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cb7cx.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cb7cx.png&quot; alt=&quot;G-AIRMET.  Why valid time after issued time?&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;For this G-AIRMET map, why is the valid time earlier than the time it was issued?&lt;/p&gt;&#xA;" OwnerUserId="12668" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-05-21T15:04:40.357" Title="Why is this G-AIRMET's valid time earlier than its issued time?" Tags="&lt;weather&gt;" AnswerCount="0" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="24933" PostTypeId="2" ParentId="24918" CreationDate="2016-02-05T01:48:48.703" Score="5" Body="&lt;p&gt;We might speculate &lt;em&gt;why&lt;/em&gt; the METAR is giving innaccurate data, but the question asks, &lt;strong&gt;&amp;quot;What should one &lt;em&gt;do&lt;/em&gt;...&amp;quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;I will take the liberty of inferring the question to be &lt;em&gt;&amp;quot;what should one do if one is unable to obtain an altimeter setting for the airport from which he or she is preparing to depart?&amp;quot;&lt;/em&gt; Note that this question could be asked due to an airport with a faulty weather reporting system (as in the question above), an airport without weather reporting at all (quite common, for example: &lt;a href=&quot;https://skyvector.com/airport/D42/Springfield-Municipal-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;D42&lt;/a&gt; or &lt;a href=&quot;https://skyvector.com/airport/S68/Orofino-Municipal-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;S68&lt;/a&gt;), or an aircraft that is not radio equipped.&lt;/p&gt;&#xA;&lt;p&gt;I will further take the liberty of answering from what I know: the FAA regulations.&lt;/p&gt;&#xA;&lt;p&gt;I will point out that it is the pilot's responsibility to be familiar with all available information and this should include a thorough weather briefing whenever possible.&lt;/p&gt;&#xA;&lt;p&gt;Under the FAA's jurisdiction, the relevant regulation is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1121&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.121 (a) (1)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Each person operating an aircraft shall maintain the cruising altitude or flight level of that aircraft, as the case may be, by reference to an altimeter that is set, when operating—&lt;/p&gt;&#xA;&lt;p&gt;(1) Below 18,000 feet MSL, to—&lt;/p&gt;&#xA;&lt;p&gt;(i) The current reported altimeter setting of a station along the route and within 100 nautical miles of the aircraft;&lt;/p&gt;&#xA;&lt;p&gt;(ii) If there is no station within the area prescribed in paragraph (a)(1)(i) of this section, the current reported altimeter setting of an appropriate available station; or&lt;/p&gt;&#xA;&lt;p&gt;(iii) In the case of an aircraft not equipped with a radio, the elevation of the departure airport or an appropriate altimeter setting available before departure&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;(Since all airports and terrain in the US are below 18,000 MSL, this applies to takeoff; the rules governing flight above 18,000—&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1121&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.121 (a) (2)&lt;/a&gt;—do not apply to our question. &lt;em&gt;&amp;quot;Operate&amp;quot;&lt;/em&gt; is defined in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a354ece82ca220cd8be8adfc35eac968&amp;amp;mc=true&amp;amp;node=se14.1.1_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 1.1&lt;/a&gt;.)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;We can go through this like a flowchart:&lt;/p&gt;&#xA;&lt;p&gt;If &lt;strong&gt;&amp;quot;the current reported altimeter setting of a station along the route and within 100 nautical miles of the aircraft&amp;quot;&lt;/strong&gt; is available, use that.&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;(Note that this could include current reported altimeter settings obtained by radio (ATC, flight service, or a nearby airport), phone call (briefer or AWOS), internet, or any other method that would procure the needed data.)&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;If no such station is available, then use &lt;strong&gt;&amp;quot;the current reported altimeter setting of an appropriate available station.&amp;quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Now, if the aircraft in question is not equipped with a radio, then (and I would read technically &lt;em&gt;only then&lt;/em&gt;) the pilot is permitted to set the altimeter to &lt;strong&gt;&amp;quot;the elevation of the departure airport or an appropriate altimeter setting available before departure.&amp;quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Now, that being said, if a pilot is in the middle of the Idaho backcountry at Wilson Bar &lt;a href=&quot;https://skyvector.com/airport/C48/Wilson-Bar-USFS-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;(C48)&lt;/a&gt;, or on the face of an Alaskan glacier, with no cell reception and no real way to acquire a current reported altimeter setting despite being in a radio equipped aircraft, then actual practice will be to set the altimeter to field elevation and get on with it. However, the requirement to use a current reported altimeter setting remains, and should be acquired at the first available opportunity.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-05T12:08:05.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24934" PostTypeId="1" AcceptedAnswerId="24938" CreationDate="2016-02-05T02:18:25.900" Score="20" ViewCount="12125" Body="&lt;p&gt;What are the advantages of a Trimmable Horizontal Stabilizer (THS)? For example, a THS is used on some Airbus and Embraer aircraft. What is the most important advantage, and why don't some other successful airliners have this type of horizontal stabilizer?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9RQY4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9RQY4.jpg&quot; alt=&quot;ERJ-170 THS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;em&gt;Image used under CC BY-SA 3.0 (&lt;a href=&quot;https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/media/File:Trimmable_horizontal_stabiliser.JPG&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;). Depicting the right side THS on an ERJ-170&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sub&gt;&lt;strong&gt;Note:&lt;/strong&gt; A &lt;a href=&quot;http://www.skybrary.aero/index.php/Trimmable_Horizontal_Stabiliser&quot; rel=&quot;noreferrer&quot;&gt;Trimmable Horizontal Stabilizer (THS)&lt;/a&gt; differs both from a &lt;a href=&quot;http://www.skybrary.aero/index.php/Stabilator&quot; rel=&quot;noreferrer&quot;&gt;Stabilator&lt;/a&gt; and a horizontal stabilizer with a trimmable &lt;a href=&quot;http://www.skybrary.aero/index.php/Elevator&quot; rel=&quot;noreferrer&quot;&gt;Elevator&lt;/a&gt;&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="12720" LastEditDate="2016-02-05T13:26:26.480" LastActivityDate="2020-06-24T19:03:20.643" Title="What are the advantages of a Trimmable Horizontal Stabilizer?" Tags="&lt;aircraft-design&gt;" AnswerCount="5" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24935" PostTypeId="1" CreationDate="2016-02-05T02:52:25.193" Score="36" ViewCount="10817" Body="&lt;p&gt;I have read that jet engines, at least the under-wing ones, are attached to the airplane by shear nuts and bolts so that in case of unstable forces in or on the engine, the engine would fall off to prevent further damage to the airframe. Have there been any incidents and or accidents where the engine has fallen off the plane in accordance to this design feature?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-06-08T01:04:14.343" LastActivityDate="2019-05-04T22:48:30.453" Title="Have jet engines ever &quot;Sheared&quot; off?" Tags="&lt;jet-engine&gt;&lt;aviation-history&gt;" AnswerCount="4" CommentCount="18" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24937" PostTypeId="2" ParentId="24935" CreationDate="2016-02-05T07:20:22.587" Score="21" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 727&lt;/a&gt; acquired a reputation for shedding engines. The process was ice buildup on the right side due to leaking lavatory plumbing, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2361/where-does-my-pee-go-when-i-flush-at-35-000-ft/14065#14065&quot;&gt;ice falling off and into the No. 3 engine&lt;/a&gt; where it caused damage to the fan blades. The resulting imbalance lead to vibrations, and the engine was designed to shear off in that case.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nytimes.com/1990/01/05/us/jet-lands-after-an-engine-drops-off.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;This New York Times article&lt;/a&gt; describes one case where a 727 lost its engine over Florida. The article continues:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cases of engines falling from airplanes are rare. In 1974 a National&#xA;  Airlines 727 lost an engine near Sierra Blanca, Tex. In 1985 an&#xA;  American Airlines 727 flying from Dallas to San Diego lost an engine&#xA;  near Deming, N.M.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would expect this happened also to some Russian airplanes, but here the reporting is less up-front, so I know of none.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-02-05T07:20:22.587" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24938" PostTypeId="2" ParentId="24934" CreationDate="2016-02-05T07:36:02.967" Score="13" Body="&lt;p&gt;The main advantage is smaller elevator deflection angles. This comes handy in two cases:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When high-lift devices are deployed, the center of pressure on the wing shifts backwards by up to a third of wing chord. Fowler flaps add wing area aft of the trailing edge, and slotted flaps are able to generate high suction peaks. The result is a massive change in trim, and the empennage now has to generate generous downforce. Changing the lift on the empennage by elevator deflection alone will exceed the maximum practicable deflection angle and leave no margin for control. By adjusting the stabilizer incidence, the elevator can be held near its neutral position and has reserves for control.&lt;/li&gt;&#xA;&lt;li&gt;In transsonic flight the elevator might not always have a linear characteristic. The contour break due to an elevator deflection induces shocks which in turn lead to &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;flow separation&lt;/a&gt; which reduces the control effectivity and can even reverse the control characteristic. Since the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight/5004?s=12%7C0.1279#5004&quot;&gt;transition from subsonic to supersonic flight&lt;/a&gt; shifts the center of lift backwards, the empennage needs to add downforce when the aircraft accelerates in the transsonic speed range. An elevator deflection might not be able to produce the desired lift change, and only adjusting the stabilizer such that the elevator can be held neutral can restore trim and control effectiveness.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Older airliners from the propeller age had lower wing loadings and less powerful flaps. The center of lift on the wing changed less with flaps, so a fixed stabilizer was sufficient. But once the wing loading goes up to jet levels, and the wing is fitted with &lt;a href=&quot;https://aviation.stackexchange.com/questions/13584/why-do-airfoils-trailing-edges-point-downward/13597#13597&quot;&gt;slotted fowler flaps&lt;/a&gt;, a moveable stabilizer is unavoidable.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-02-05T08:40:17.993" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24939" PostTypeId="2" ParentId="24935" CreationDate="2016-02-05T10:04:03.470" Score="22" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/El_Al_Flight_1862&quot; rel=&quot;noreferrer&quot;&gt;ELAL flight 1862&lt;/a&gt; crashed in Amsterdam on the 4th of October 1992 as a result of 2 engines shearing off. The number 3 engine sheared off shortly after take-off due to metal fatigue related failure of the fuse pins. After separation, the number 3 engine hit the number 4 engine, shearing it off as well. Combined with damage to the leading edge of the right wing the aircraft became difficult to control at low speeds and subsequently crashed on the attempt to return to Schiphol Airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://web.archive.org/web/20090205093738/http://verkeerenwaterstaat.nl/kennisplein/uploaded/MIN/2005-07/39448/ElAl_flight_1862.pdf&quot; rel=&quot;noreferrer&quot;&gt;Official accident investigation report&lt;/a&gt; (PDF)&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="12220" LastEditDate="2016-02-09T03:24:40.283" LastActivityDate="2016-02-09T03:24:40.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24940" PostTypeId="2" ParentId="24935" CreationDate="2016-02-05T10:54:18.277" Score="31" Body="&lt;p&gt;Engine shearoff, though rare, has happened in a number of cases. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Boeing 747F experienced a number of engine falloffs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On Dec 1991, &lt;a href=&quot;https://en.wikipedia.org/wiki/China_Airlines_Flight_358&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines flight 358&lt;/a&gt;, a 747-200F, lost an engine near Taiwan and crashed.&lt;/li&gt;&#xA;&lt;li&gt;On October 1992, a &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=1&amp;amp;LLID=38&amp;amp;LLTypeID=2#null&quot; rel=&quot;nofollow noreferrer&quot;&gt;El Al 747-200F&lt;/a&gt; crashed after takeoff due to engine separation, at Amsterdam, the Netherlands. &lt;/li&gt;&#xA;&lt;li&gt;Another 747F from Evergreen Airlines lost an engine over Anchorage, Alaska soon after. &lt;/li&gt;&#xA;&lt;li&gt;On October 2004, a &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20041020-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-132SF of Kalitta Air&lt;/a&gt; lost an engine while climbing and landed without further incident.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Engine separation has been reported on 737s too:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In November 2007, &lt;a href=&quot;http://blog.flightstory.net/385/737-200-looses-engine-at-cpt-pictures/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight CE723, a Nationwide 737-200&lt;/a&gt; lost an engine during takeoff; the aircraft was landed without further incident.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On December 1987, &lt;a href=&quot;http://www.ntsb.gov/about/employment/_layouts/ntsb.aviation/brief.aspx?ev_id=20001213X32769&amp;amp;key=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;USAIR FLT 224&lt;/a&gt;, B737, lost an engine during climb; the aircraft was landed successfully.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are cases where engine separation has occurred in &lt;a href=&quot;http://aviation-safety.net/database/record.php?id=19920331-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;B707&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Northwest_Airlines_Flight_5&quot; rel=&quot;nofollow noreferrer&quot;&gt;B727&lt;/a&gt;, and &lt;a href=&quot;http://avstop.com/news/engine_separation_causes_american_airlines_flight_191_to_crash.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;DC-10&lt;/a&gt;. &lt;a href=&quot;http://aviation-safety.net/database/dblist.php?Event=ACES&quot; rel=&quot;nofollow noreferrer&quot;&gt;aviation-safety.net&lt;/a&gt; has a list of engine separation incidents.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-05-04T21:37:16.107" LastActivityDate="2019-05-04T21:37:16.107" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="24941" PostTypeId="2" ParentId="3300" CreationDate="2016-02-05T11:19:20.817" Score="3" Body="&lt;p&gt;The only answer that matters is safety, because it makes all the others unimportant. Assuming fixed pitch rotors, if you Lose power to a rotor, you're going to crash, and you will crash in an uncontrolled way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could gain more control by adding more rotors, but the more rotors you add, the higher the likelihood of a failure of one rotor. Also, for each rotor you add, you'll lose rotational inertia in each rotor, the result being that in a loss of power event, even collective pitch rotors will be unable to provide sufficient lift to keep you from dying of rapid deceleration sickness. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-02-05T11:19:20.817" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24942" PostTypeId="1" CreationDate="2016-02-05T11:58:24.073" Score="4" ViewCount="512" Body="&lt;p&gt;In some Airbus planes, they have heated floor panels. So, what kind of heaters are being used there? &lt;/p&gt;&#xA;" OwnerUserId="5694" LastActivityDate="2021-02-24T17:53:28.140" Title="What kind of heaters are used for heated floor panels?" Tags="&lt;airbus&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24943" PostTypeId="2" ParentId="24934" CreationDate="2016-02-05T14:53:42.397" Score="8" Body="&lt;p&gt;Trimmable horizontal stabilizers (THS) are found in majority of airliners and large transport aircraft (like C-17 globemaster III, for example). They are usually part of the trimming system of the aircraft, unlike the elevators, which are controlled by conventional pilot inputs (like yoke etc.). The THS offers some important advantages like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The required elevator deflection angles are smaller in case of trimmed aircraft and the system has full elevator deflection angles at extreme trim angles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the stabilizer is not trimmed, the (human or auto)pilot has to continuously adjust the controls to prevent the aircraft from pitching up or down more than required.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aligning the elevator with the stabilizer reduces drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It allows for a wider range of c.g. movement compared to the elevator-trim tab system.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The decision to use a THS (or not) depends on the design. For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Aerospace_146&quot; rel=&quot;noreferrer&quot;&gt;BAe 146&lt;/a&gt; had a fixed tail plane in order to reduce complexity (achieved in part by the elimination of leading edge slats). The THS does add more complexity to the system and has been involved in a few accidents, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261&quot; rel=&quot;noreferrer&quot;&gt;Alaska Airlines Flight 261&lt;/a&gt; and &lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=3&amp;amp;LLID=64&amp;amp;LLTypeID=2#&quot; rel=&quot;noreferrer&quot;&gt;China Airlines Flight 140&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stabilator or all moving tailplane is entirely different (with no elevators) and is mostly used in supersonic aircraft. It is used mainly to overcome the problem where elevator becomes unusable due to shockwaves produced by tailplane and the problem of &lt;a href=&quot;https://en.wikipedia.org/wiki/Mach_tuck&quot; rel=&quot;noreferrer&quot;&gt;Mach tuck&lt;/a&gt;. Combat aircraft to use them as they create a large pitching moment for lesser control effort. Also, they are used for roll control via differential movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In civil aircraft, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_L-1011_TriStar&quot; rel=&quot;noreferrer&quot;&gt;Lockheed L-1011 Tristar&lt;/a&gt; used stabilators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fQ9ZA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fQ9ZA.jpg&quot; alt=&quot;L-1011 stabilator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from tristar500.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also used in some GA aircraft (like Piper Cherokee); the strong control response of the stabillator can result in overcorrection- this is overcome in part by using an anti-servo tab.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-05T14:53:42.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24944" PostTypeId="1" AcceptedAnswerId="24958" CreationDate="2016-02-05T15:31:40.107" Score="4" ViewCount="843" Body="&lt;p&gt;What are the most common reasons that cause an aircraft to depressurize while flying? For example, a broken window, a failure on the Outflow Valve, etc.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="6979" LastEditDate="2016-02-06T10:11:11.137" LastActivityDate="2016-02-06T10:11:11.137" Title="What are the most common reasons an aircraft to depressurize while flying?" Tags="&lt;aircraft-systems&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="9" ClosedDate="2016-02-12T08:17:06.270" ContentLicense="CC BY-SA 3.0" />
  <row Id="24945" PostTypeId="2" ParentId="24935" CreationDate="2016-02-05T15:54:15.920" Score="15" Body="&lt;p&gt;In addition to the cases where engines fell off in flight, there have also been cases where the engines sheared off due to impact forces during a crash, which is the primary reason for attaching to the wing with shear pins. This helps to prevent excessive loads from breaking the wing structure, which would cause a fuel leak from the tanks in the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20130706-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;July 2013&lt;/a&gt;, an Asiana 777-200ER crashed short of the runway. Both engines separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20130413-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;April 2013&lt;/a&gt;, a Lion Air 737-800 crashed short of the runway. The right hand engine sheared off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20090225-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;February 2009&lt;/a&gt;, a Turkish Airlines 737-800 crashed, both engines separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aviation-safety.net/database/record.php?id=20081220-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;December 2008&lt;/a&gt;, a Continental 737-500 departed the runway on takeoff. One engine separated.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2019-05-04T22:48:30.453" LastActivityDate="2019-05-04T22:48:30.453" CommentCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="24946" PostTypeId="1" CreationDate="2016-02-05T16:40:59.820" Score="5" ViewCount="1598" Body="&lt;p&gt;How much does a Ballistic Recovery Systems parachute system weigh?  I wouldn't want to use a personal quadcopter or jetpack without one.  I wonder if they could be made small and light enough for a small JB-9 type jetpack.  &lt;/p&gt;&#xA;" OwnerUserId="13356" LastEditorUserId="19" LastEditDate="2016-06-27T07:57:35.427" LastActivityDate="2016-06-27T07:57:35.427" Title="What is the weight of ballistic recovery systems?" Tags="&lt;airframe-parachute&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24947" PostTypeId="2" ParentId="24946" CreationDate="2016-02-05T16:56:17.967" Score="8" Body="&lt;p&gt;The &lt;a href=&quot;http://www.brs-vertrieb.de/specifications/&quot;&gt;smallest BRS listed here&lt;/a&gt; is certified up to 600 pounds (272 kg) of aircraft weight. That should be more than enough for a small jetpack or personal quadcopter. This system weighs about 22 pounds (10 kg), not counting anything required to install it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As GdD mentioned, altitude may be an issue. The &lt;a href=&quot;http://www.brsaerospace.com/cessna_182_faq.aspx&quot;&gt;FAQ for a Cessna 182&lt;/a&gt; mentions an altitude loss of about 300 feet, and that is with a rocket deployment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They make systems for &lt;a href=&quot;http://www.brsaerospace.com/advice_to_owners.aspx&quot;&gt;many different types of aircraft and ultralights&lt;/a&gt;, some probably smaller than the 600 pound limit listed above. You should contact them if you have a serious interest in such a system.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastActivityDate="2016-02-05T16:56:17.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24949" PostTypeId="1" AcceptedAnswerId="24953" CreationDate="2016-02-05T18:55:20.983" Score="2" ViewCount="7267" Body="&lt;p&gt;Here you can see two of them on the B747. What are they and what's their function?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Fmezx.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fmezx.png&quot; alt=&quot;747&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: FAA's Pilot's Handbook of Aeronautical knowledge&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T18:05:58.640" LastActivityDate="2016-03-05T18:05:58.640" Title="What is a Pressurization Safety Valve?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24950" PostTypeId="1" AcceptedAnswerId="24951" CreationDate="2016-02-05T19:43:58.870" Score="10" ViewCount="1624" Body="&lt;p&gt;I've read that it's recommended to store a plane with full fuel tanks to prevent water contamination.  Some small general aviation planes, however, would exceed their maximum gross take off weight with full fuel and just two adult passengers of average weight.  One option, of course, is to fly with less than a full fuel tank.  This seems like it could be a problem if 50 gallons of fuel need to be dumped which cost the pilot $300.  My question is: &lt;b&gt;what does a pilot do with the extra fuel that needs to be discarded before the flight?&lt;/b&gt;&lt;/p&gt;&#xA;" OwnerUserId="8389" LastActivityDate="2019-11-19T18:20:44.340" Title="What to do with excess fuel before flight?" Tags="&lt;general-aviation&gt;&lt;fuel&gt;&lt;fuel-tanks&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24951" PostTypeId="2" ParentId="24950" CreationDate="2016-02-05T20:01:51.360" Score="13" Body="&lt;p&gt;You have a few options, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You can burn it off&lt;/strong&gt;. Laps in the pattern are great for this. Get to the airport before you need to depart and practice some landings. This may cost you in terms of dollars but at least you are not just dumping it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;You can dump it into gas cans if you have them&lt;/strong&gt;. Every small GA plane i have ever encountered (mostly pipers) has fuel sumps for testing your fuel during your preflight. Most of these sumps can be latched open and you can drain it into a gas can for use later. you should always test for water before doing this. If you rent you should ask the FBO what their policies are on dumping/reusing fuel. I cant find any specific legislation on it but it seems that its common practice (for the airlines at least) to only put the fuel back in the same plane (or within the same fleet) to prevent cross contamination of things that can build up in the tanks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The sump on the pipers I fly looks like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MaxVG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MaxVG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://3.bp.blogspot.com/-rbXTnEuDmno/VVealO1EkoI/AAAAAAAAAzE/OrR31tBUxhM/s1600/IMG_2029.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dont have the plane filled up&lt;/strong&gt;. If you rent planes like many GA pilots do and you plan to take up 4 friends for an evening sight seeing flight ask the FBO to not fill the tanks if someone is using it before you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dont use all the tanks&lt;/strong&gt;. This will vary plane to plane but some planes have 2 or more fuel tanks which may be independently selectable. You may be able to (weight and balance permitting) keep some of the tanks dry if you know you regularly short hops with big loads. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of a complete answer I will mention that planes can be flown over gross weight, I don't advocate this nor would I ever attempt it but it does happen here and there, &lt;a href=&quot;http://www.airliners.net/forum/viewtopic.php?f=5&amp;amp;t=744969&quot; rel=&quot;nofollow noreferrer&quot;&gt;here is a discussion on it if you are curious&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2019-11-19T18:20:44.340" LastActivityDate="2019-11-19T18:20:44.340" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="24952" PostTypeId="2" ParentId="24949" CreationDate="2016-02-05T20:22:08.070" Score="2" Body="&lt;p&gt;The purpose of pressurization safety valves is to prevent too large differential pressure in the pressure-hull.&lt;br&gt;&#xA;The safety valve(s) are normally closed, and they're set to open in a certain differential pressure. So for example in case the normal outflow valve fails for some reason and is closed, and the ac-packs continue to push pressure in the cabin, the safety valve opens thus maintaining a safe differential pressure.&lt;br&gt;&#xA;They are a part of the pressure hull &quot;safety back-ups&quot; just like the negative pressure relief valve too.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-02-05T20:22:08.070" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24953" PostTypeId="2" ParentId="24949" CreationDate="2016-02-05T22:52:36.077" Score="5" Body="&lt;p&gt;The pressurization relief valves are on the left side of the fuselage and are used to provide protection (for the aircraft) against excessive differential pressures. In this case, they are set to open at a differential pressure of 63.8 KPa (with 66.9 KPa) as a backup. From &lt;a href=&quot;http://atsb.gov.au/publications/investigation_reports/2008/aair/ao-2008-053.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATSB Investigation Report on the depressurization of Boeing 747 VH-OJK&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The relief valves provided protection to the aircraft against excessive differential pressures, with the external latching doors providing a positive indication of valve operation. Aircraft systems documentation&#xA;  specified that the valves open at a differential pressure of 63.8 kPa (9.25 psi) to vent the fuselage interior to the ambient atmosphere. An additional relief setting of 66.9 kPa (9.7 psi) acts as a backup.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same report shows the external blowout doors of the (both) relief valves open, as shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ee0Qj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ee0Qj.jpg&quot; alt=&quot;Pressure relief valve&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a related note, there is a negative pressure relief valve to prevent vacuum damage to aircraft during a rapid descent. Usually, this is a spring loaded valve that opens inwards at negative pressure differential.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-05T22:52:36.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24954" PostTypeId="1" AcceptedAnswerId="24967" CreationDate="2016-02-05T23:27:42.717" Score="14" ViewCount="1313" Body="&lt;p&gt;Going off &lt;a href=&quot;https://aviation.stackexchange.com/questions/24935/have-jet-engines-ever-sheared-off#comment58667_24935&quot;&gt;this&lt;/a&gt; question, what happens to the fuel lines to the engine when it falls off? Does it automatically shut off or do the pilots have to manually do it?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="19" LastEditDate="2017-05-15T08:14:41.117" LastActivityDate="2017-05-15T08:14:41.117" Title="What happens to the fuel lines when a jet engine falls off?" Tags="&lt;jet-engine&gt;&lt;fuel-line&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24955" PostTypeId="2" ParentId="24954" CreationDate="2016-02-06T01:20:40.263" Score="3" Body="&lt;p&gt;I'm not aware of any automatic fuel shutoff valve in case of engine seperation. The pilot has to manually close the fuel shutoff valve to prevent fuel loss. From &lt;a href=&quot;http://www.b737.org.uk/enginemalfunctions.htm&quot; rel=&quot;nofollow&quot;&gt;b737.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Engine separation is an extremely rare event. ... It is important to use the fire handle to close the spar valve and prevent a massive overboard fuel leak; refer to the airplane flight or operations manual for specific procedures. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, see &lt;a href=&quot;https://books.google.co.in/books?id=lJorAAAAYAAJ&amp;amp;pg=PA75&amp;amp;lpg=PA75&amp;amp;dq=fuel+line+during+engine+separation&amp;amp;source=bl&amp;amp;ots=KqXQgCdGIL&amp;amp;sig=oFLRg0n2QFdX4BQ7rUY3_j8WYe8&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwja2d-67OHKAhXMJI4KHfK_D5oQ6AEIJDAB#v=onepage&amp;amp;q=fuel%20line%20during%20engine%20separation&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-06T01:20:40.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24956" PostTypeId="1" CreationDate="2016-02-06T02:55:19.940" Score="4" ViewCount="135" Body="&lt;p&gt;Are there statistics about how many Aircraft emergency evacuation incidents (land-based) in the recent past (say, last 10 years) actually were followed by significant fires?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &quot;significant&quot; I mean fires large enough to spread to the passenger cabins in spite of fire fighting attempts &amp;amp; which may conceivably have led to fatalities had passengers still been on board. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The context of what I am asking is: Are we doing a good job balancing the upside &amp;amp; downside risks of an Evac? Keeping in mind that &lt;s&gt;most&lt;/s&gt; some Evacs can come with serious injuries to passengers. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-07-11T08:42:21.100" LastActivityDate="2016-07-11T08:42:21.100" Title="Which evacuation incidents were followed by a large fire?" Tags="&lt;fire&gt;&lt;evacuation&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24957" PostTypeId="1" AcceptedAnswerId="24961" CreationDate="2016-02-06T05:36:57.973" Score="4" ViewCount="347" Body="&lt;p&gt;Imagine a hypothetical scenario where a jet heavily loaded with fuel experiences more than one engine failures after $V_{1}$. Then I suppose that losing some weight would be beneficial since the airplane is not designed to sustain climb with such limited thrust. In such a case a) how much would dumping fuel help in this emergency (i.e. is the rate of dumping fast enough?) and b) could the captain proceed to do it without ATC authorization if he/she considers it necessary?&lt;/p&gt;&#xA;" OwnerDisplayName="user13363" LastEditorUserId="19" LastEditDate="2016-07-14T07:09:30.697" LastActivityDate="2016-07-14T07:09:30.697" Title="In an emergency situation just after take off, is fuel dumping useful?" Tags="&lt;emergency&gt;&lt;takeoff&gt;&lt;fuel-dumping&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24958" PostTypeId="2" ParentId="24944" CreationDate="2016-02-06T06:08:28.843" Score="5" Body="&lt;p&gt;The most common failure leading to depressurization I've personally seen is a pack/air cycle machine failure. The equipment that takes pressurized bleed air from the engine, cools and expands it. I've seen it happen two ways. 1) The aircraft is dispatched with one pack on MEL and the second pack fails in flight or 2) The aircraft is flying at high altitude, 1 pack fails, the other pack switches to high flow mode and fails soon after.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pack failure is by far the most common I've seen. But have also seen a couple failed fuselage skins and a few burst PAX windows. Typically door leaks are enough to be noisy as heck, but not depressurize the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-02-06T06:08:28.843" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24959" PostTypeId="2" ParentId="23535" CreationDate="2016-02-06T06:20:20.963" Score="1" Body="&lt;p&gt;Generally Boeing struts use military hydraulic fluid (red oil) MIL-H-5606 and dry nitrogen as the charge. Many military aircraft have upgraded to synthetic hydraulic fluids that are fully compatible with MIL-H-5606, like MIL-PRF-83282 or MIL-PRF-87257. Sooner or later this will probably get adopted by airlines as well. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-02-06T06:20:20.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24960" PostTypeId="2" ParentId="3709" CreationDate="2016-02-06T06:38:09.347" Score="2" Body="&lt;p&gt;1) The spinning wheels will cause vibrations until they are stopped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) It is good practice to stop your wheel after you lift off due to flailing tread. Flailing tread can do a lot of damage, especially if it becomes thrown tread. After you stop the tire rotation, it just becomes &quot;hanging tread&quot; and will not do any damage. This is why commercial airlines have systems in place to automatically apply the brakes on retraction and the nose tires get pressed against &quot;spin brakes.&quot; Also by learning the practice with fixed gear aircraft, it is more likely to be second nature when you move up to retractable gear. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-02-06T06:38:09.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24961" PostTypeId="2" ParentId="24957" CreationDate="2016-02-06T08:59:08.700" Score="5" Body="&lt;p&gt;You would not attempt this. Aircraft are certified to climb with engines inoperative after V1, they would just climb to a holding altitude and run the checklist. They would rather not attempt to any cruise altitude. Running the checklist you would determine if you are above the maximum landing weight (MLW) and decide to burn or if able, to dump fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dumping fuel during the takeoff/rotation phase is not advisable to be honest, as you would leave a contaminated runway behind. Sure, most of the fuel will evaporate, but there will be a contamination nonetheless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will quote &lt;a href=&quot;https://aviation.stackexchange.com/users/2546/nate-eldredge&quot;&gt;Nate Eldredge&lt;/a&gt;'s comment shamelessly for another item to consider:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to &lt;a href=&quot;https://aviation.stackexchange.com/q/8136/572&quot;&gt;How is fuel dumped in aircraft?&lt;/a&gt; a 747 can dump 6000 pounds of fuel per minute. Given that (from what I found) it typically carries at least 200,000 pounds, and has an MTOW of over 800,000 pounds, it seems unlikely you'd dump enough fuel fast enough to make any difference.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-06T08:59:08.700" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24962" PostTypeId="2" ParentId="16437" CreationDate="2016-02-06T11:02:56.187" Score="1" Body="&lt;p&gt;Simply retractable landing gear is made so as to reduce extra drag which created by the fixed landing gear and hence heavier than air aircraft(airplane) can improve in speed and travel at high speed at higher altitude&lt;/p&gt;&#xA;" OwnerUserId="13368" LastActivityDate="2016-02-06T11:02:56.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24963" PostTypeId="1" AcceptedAnswerId="24974" CreationDate="2016-02-06T11:54:53.010" Score="13" ViewCount="5881" Body="&lt;p&gt;Why do Boeing's new generation of jets (787, 747-8, 777X, 737MAX) have &lt;a href=&quot;http://www.aerospaceweb.org/aircraft/jetliner/b787/b787_12.jpg&quot; rel=&quot;noreferrer&quot;&gt;serrated engine nacelles&lt;/a&gt; whilst Airbus' latest (A350, A320neo etc) do not? I understand that &lt;a href=&quot;https://aviation.stackexchange.com/questions/12832/why-does-the-boeing-787-engine-nacelle-exhaust-have-such-an-unusual-shape&quot;&gt;Boeing's nacelles reduce turbulence and therefore noise&lt;/a&gt;. If this is the case, it would make sense for Airbus to utilise them as well, but it doesn't. So my question is, is this a patent thing or has Airbus found other ways to do the same thing?&lt;/p&gt;&#xA;" OwnerUserId="13369" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2021-01-18T04:10:29.313" Title="Why do Boeing aircraft have serrated engine nacelles, but Airbus does not?" Tags="&lt;aircraft-design&gt;&lt;boeing&gt;&lt;airbus&gt;&lt;nacelle&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24964" PostTypeId="1" AcceptedAnswerId="24976" CreationDate="2016-02-06T13:02:47.470" Score="-5" ViewCount="21697" Body="&lt;p&gt;I've just done some research on the Boeing 787 and the 737. But the 787 and 737 MAX seem almost completely alike. Are there any differences between the 787 and the 737 MAX?&lt;/p&gt;&#xA;" OwnerUserId="8960" LastEditorUserId="12720" LastEditDate="2016-02-06T14:37:13.343" LastActivityDate="2016-02-06T19:59:27.567" Title="Is there any difference between the Boeing 787 and the 737 MAX?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;boeing-787&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-02-06T21:07:21.827" ContentLicense="CC BY-SA 3.0" />
  <row Id="24965" PostTypeId="1" CreationDate="2016-02-06T13:04:03.480" Score="7" ViewCount="9443" Body="&lt;p&gt;Are tyres custom designed for each new aircraft model or is there a lot of standardization &amp;amp; cross use across models? When a designer starts on a new model is there a list of standard tire sizes to choose from? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the situation similar for general aviation / military aircraft? &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-06-28T22:27:32.637" LastActivityDate="2016-06-28T22:27:32.637" Title="Are aircraft tyre sizes standardised?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24966" PostTypeId="2" ParentId="24964" CreationDate="2016-02-06T13:17:55.200" Score="10" Body="&lt;p&gt;The main difference is size and purpose. Despite being larger than most 737 variants, the 737-MAX is still a smaller, short haul plane. It carries 180 passengers to the 787's 280, has a range of 3630 nautical miles to the 787s 7635. Above all, the 737-MAX is still a narrow bodied jet, while the 787 is a wide body. All of this means that the 737 MAX is still a smaller jet better tailored to domestic flights, while the 787 is a medium to large jet (depending on the variant) intended for international flying.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="12220" LastEditDate="2016-02-06T13:32:28.893" LastActivityDate="2016-02-06T13:32:28.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24967" PostTypeId="2" ParentId="24954" CreationDate="2016-02-06T13:45:42.623" Score="15" Body="&lt;p&gt;Engine separation won't cause automatic closure of valves, but the resulting low pressure will illuminate lights (including the Master Caution light) on the panels and display messages on the displays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots will have to react to the engine separation, the same way than for an engine fire or severe malfunction. This &lt;em&gt;non normal&lt;/em&gt; procedure includes shutting down the fuel line by setting the engine start lever to CUTOFF or triggering the fire bottles on the affected engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a &lt;em&gt;spar fuel valve&lt;/em&gt; (or &lt;em&gt;fuel shutoff valve&lt;/em&gt;) fixed to the wing and to the fuel tank, which stays on the wing in case of separation. This valve is to prevent leaks due to a broken line. As the hydraulic power may be missing after the engine damage or separation, the valve is controlled by an electric motor with a backup battery and a double wiring redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example on the the B737 NG:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hanEk.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hanEk.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Shut-off valves framed in purple, &lt;a href=&quot;http://www.b737.org.uk/fuel.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-Normal checklist used: &lt;code&gt;ENGINE FIRE or Engine Severe Damage or Separation&lt;/code&gt; (NNC 8.2 of the Quick Reference Handbook).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vU41F.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vU41F.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Click to enlarge, &lt;a href=&quot;http://www.737ng.co.uk/737-800%20Quick%20Reference%20Handbook%20%28QRH%29.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-02-07T14:54:03.943" LastActivityDate="2016-02-07T14:54:03.943" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24968" PostTypeId="2" ParentId="24965" CreationDate="2016-02-06T14:24:36.437" Score="8" Body="&lt;h2&gt;Aircraft tires are indeed standardized by size and specification and with applications across models.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;There is certainly a long list of available sizes and variations, just as with automotive tires. When needed for a new aircraft type design, these existing tire models are available to be incorporated into that design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are certainly many aircraft types that have necessitated special tire specifications through the history of aviation development, especially with the more esoteric military aircraft. Of course, this is how that extensive list of available tires came to be.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Aircraft tires are dimensioned by several measurements (as depicted in the images below):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Outside Diameter (A),&lt;/li&gt;&#xA;&lt;li&gt;Cross Sectional Width (B),&lt;/li&gt;&#xA;&lt;li&gt;and Inner (Rim) Diameter (C).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;These dimensions will be noted as AxB-C. In some cases the A is left out for a B-C notation (see examples in the table of &quot;Type III Nylon Tube Type Tires&quot; below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Jm796.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Jm796.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sub&gt;Image &lt;a href=&quot;http://navyaviation.tpub.com/14018/css/14018_423.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gJKBs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gJKBs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sub&gt;Image &lt;a href=&quot;http://www.bowersflybaby.com/tech/wheel_selection.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aircraftsupply.com/specialty-air-hawk-aircraft-tires.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air Hawk&lt;/a&gt; tires are one brand that I handle frequently; their tire products give a good representation of the generic sizes and specifications available. Follow the above link for examples from their online catalog.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this excerpt from their &lt;a href=&quot;http://www.aircraftsupply.com/pdf-files/Air-Hawk-Specifications.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aircraft Tires Specifications&lt;/a&gt; sheet showing examples of common dimensions and plys:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7FYcZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7FYcZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Goodyear has an exhaustive databook covering technical specifications for their commercial and military aircraft tires. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See that here: &lt;a href=&quot;https://www.goodyearaviation.com/resources/pdf/databook_12_2015.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Aircraft Tire DataBook&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Specific data on the proper tire sizes for different aircraft main and&#xA;  auxiliary/nose gear, speed ratings, nominal inflation pressures,&#xA;  dimensions, and other data needed by users to obtain the maximum&#xA;  service from their aircraft tires are presented in this booklet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-06T14:30:51.940" LastActivityDate="2016-02-06T14:30:51.940" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="24969" PostTypeId="1" AcceptedAnswerId="24970" CreationDate="2016-02-06T14:41:44.350" Score="9" ViewCount="960" Body="&lt;p&gt;I've noticed something on the engine of this bizjet. Could somebody explain what that is? &#xA;&lt;a href=&quot;https://i.stack.imgur.com/HlY6I.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HlY6I.jpg&quot; alt=&quot;cessna 500&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Policia-Federal-Argentina/Cessna-500-Citation/2768904/L/&amp;amp;sid=54501445151b2d974b17b6267cc58d0b&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt; (image modified to indicate location of fairing).&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-28T18:18:09.930" LastActivityDate="2016-03-28T18:18:09.930" Title="What is this thing on the engine of a Cessna 500 Citation I?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;private-jets&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24970" PostTypeId="2" ParentId="24969" CreationDate="2016-02-06T14:51:33.990" Score="12" Body="&lt;p&gt;Those are the fairings containing the mechanisms for the engine's reverse thrust system. See &lt;a href=&quot;http://3.bp.blogspot.com/-zgt6trCTf2s/VkeDthBlAuI/AAAAAAAAIbs/t-FTKSAWro0/s1600/DSC_0999.JPG&quot; rel=&quot;noreferrer&quot;&gt;this photo&lt;/a&gt; (copyrighted) of the similar reverse thrust &quot;buckets&quot; deployed on a Citation 550.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this example of a similar thrust reverser system deployed on a different aircraft type:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tLA3T.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tLA3T.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;sub&gt;Image &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Klm_f100_ph-kle_arp.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;, public domain&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also Wikipedia's article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Thrust_reversal&quot; rel=&quot;noreferrer&quot;&gt;Thrust Reversal systems&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-06T14:57:49.763" LastActivityDate="2016-02-06T14:57:49.763" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24972" PostTypeId="2" ParentId="24723" CreationDate="2016-02-06T15:05:41.627" Score="2" Body="&lt;p&gt;It is definitely common here in Germany to use German checklists (German is not an ICAO language).&#xA;see &lt;a href=&quot;http://www.motorflugschule-egelsbach.de/Downloads/Diverses/C172_R04.pdf&quot; rel=&quot;nofollow&quot;&gt;http://www.motorflugschule-egelsbach.de/Downloads/Diverses/C172_R04.pdf&lt;/a&gt; for example. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However since many systems and acronyms used have English terms anyways it boils down to a combination with English. &lt;/p&gt;&#xA;" OwnerUserId="13372" LastActivityDate="2016-02-06T15:05:41.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24973" PostTypeId="1" CreationDate="2016-02-06T15:09:50.193" Score="5" ViewCount="15324" Body="&lt;p&gt;Are there advantages or disadvantages to a mid wing design for a monoplane? If so, how would this design compare to a high wing or a low wing monoplane design?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What might be the aerodynamic advantages or disadvantages?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What might be the design or structural advantages or disadvantages?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What might be the control or flight characteristic advantages or disadvantages?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13373" LastEditorUserId="12720" LastEditDate="2016-02-06T16:36:28.190" LastActivityDate="2016-02-08T21:50:57.627" Title="What are the advantages or disadvantages of a mid wing design?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;fixed-wing&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24974" PostTypeId="2" ParentId="24963" CreationDate="2016-02-06T16:08:07.727" Score="15" Body="&lt;p&gt;It doesn't appear to be a patent thing. The main work on the chevron (shaped nozzles) was done by NASA. Every design decision in an aircraft is a compromise and this was no different. The addition of chevrons for noise suppression leads to a (small) increase in specific fuel consumption and Airbus considered it not worth it. Flightglobal quotes &lt;a href=&quot;https://www.flightglobal.com/news/articles/second-chance-the-a350-204138/&quot; rel=&quot;noreferrer&quot;&gt;Dougie Hunter, A350 chief engineer&lt;/a&gt; as saying:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We didn’t get a noise advantage from chevrons, and there is a specific fuel consumption penalty, so we’ve not adopted them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airbus seems to have gone in the insulation and high bypass route for reducing noise. From the same article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Goodrich is to build the engine nacelle for the A350’s GEnx engine, with Airbus supplying the composite inlet, which incorporates a “zero splice” acoustic inner barrel to provide a new level of fan-noise reduction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As an example of the acoustic treatment of nacelle in A320 family, &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0ahUKEwim-pTRwOPKAhVNHY4KHX7NAkcQFggcMAA&amp;amp;url=http%3A%2F%2Fwww.airbus.com%2Fsupport%2Fpublications%2F%3FeID%3Dmaglisting_push%26tx_maglisting_pi1%255BdocID%255D%3D41153&amp;amp;usg=AFQjCNEOUndjKD87gNLPIzYoun8ptjNkDg&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Airbus says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The thrust reverser structure was acoustically treated along approximately&#xA;  half of its internal surface. It was clear that increasing this acoustic area would increase the acoustic sound absorption and hence decrease the overall measurable exhaust noise. The inner fixed structure was redesigned with increased acoustic area. In addition, the support struts and several fairings were also modified to include acoustic treatment. The result was an increase in the acoustic area of the thrust reverser by approximately 2 square meters (21.5 sq ft).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Airbus does use chevrons in some of the aircraft, like A321 along with nacelle acoustic improvements; however, the chevrons are available only in the inner (core) nozzle. The package is available as standard for CFM powered A321 aircraft and options are available for A320. The image below shows a A321 with chevron nozzles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0nc0S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0nc0S.jpg&quot; alt=&quot;A321 CFM&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.pprune.org/engineers-technicians/434988-why-a321-engine-different-others.html&quot; rel=&quot;noreferrer&quot;&gt;pprune.org&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0ahUKEwim-pTRwOPKAhVNHY4KHX7NAkcQFggcMAA&amp;amp;url=http%3A%2F%2Fwww.airbus.com%2Fsupport%2Fpublications%2F%3FeID%3Dmaglisting_push%26tx_maglisting_pi1%255BdocID%255D%3D41153&amp;amp;usg=AFQjCNEOUndjKD87gNLPIzYoun8ptjNkDg&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Airbus&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The noise reduction package is currently offered as the basic standard on all CFM powered Airbus A321 aircraft. It is also optional on all the other A320 Family aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-06T16:08:07.727" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24975" PostTypeId="2" ParentId="24973" CreationDate="2016-02-06T17:29:01.733" Score="2" Body="&lt;p&gt;They have a main structural advantage:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;code&gt;Mid mounted wings have the advantage of being structurally efficient when aerospace engineers desire to incorporate a swept or tapered wing design on the aircraft. This increase in structural integrity is essential for aircraft that perform extreme maneuvers or aerobatics&lt;/code&gt;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;http://studentpilotnews.com/2013/10/31/high-wing-or-low-wing-which-trainer-should-i-choose/&quot; rel=&quot;nofollow&quot;&gt;Student Pilot News&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They also leave the aircraft free of spars on the belly and room for cargo. And they reduce the induced drag&#xA;The main disadvantage is the speed. The fastest planes use low-wings. Also many of this aircraft use spars in the middle of the fuselage, so you have to have a bigger fuselage and thus more weight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is aerodynamically the cleanest and most balanced, but the carry-through spar can reduce the useful fuselage volume near its centre of gravity, where space is often in most demand. It is common on high-performance types such as sailplanes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A low wing allows the pilot to have a good visibility and a lighter structure because as it is below fuselage, it doesn't have to carry more weight. But there's also a main disadvantage which occurs when landing; it produces a strong ground effect compared to the high and mid-wing. In case of an emergency you can step out and can be used as overwing exits. And finally, they have better flexibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A high wing provides also good visibility and lateral stability. Also increases ground clearance for the engines and cargo.&#xA;More info can be found &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/74463/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/149229/&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="5517" LastEditDate="2016-02-08T21:50:57.627" LastActivityDate="2016-02-08T21:50:57.627" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24976" PostTypeId="2" ParentId="24964" CreationDate="2016-02-06T17:56:15.233" Score="8" Body="&lt;p&gt;The 787 was a brand new design. The biggest new feature is the extensive use of composite materials throughout the aircraft. The new design also uses electrical systems instead of hydraulic and bleed air systems that are used on most other aircraft. It is a wide-body aircraft, intended to carry large numbers of passengers over long ranges. The new design mostly replaces the older 767 model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://aviation.stackexchange.com/q/119/1696&quot;&gt;737 MAX&lt;/a&gt; is mostly a re-engine of a very old design. Though much has changed in multiple generations since the original 737 design, it still retains many differences from the 787. The 737 still has the same fuselage cross-section, and the aircraft is still primarily built from aluminum. Aside from fly-by-wire spoilers, hydraulics and bleed air are still used as before. While the new engines on the MAX do have chevrons like those on the 787, they are from a different manufacturer. The other key feature of the MAX, the AT winglets, distinguish it from the 787, with uses much more simple &lt;a href=&quot;https://aviation.stackexchange.com/q/19073/1696&quot;&gt;raked tips&lt;/a&gt;. The 737 still carries a much lower number of passengers, and is intended for shorter routes.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-02-06T19:59:27.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24977" PostTypeId="2" ParentId="24973" CreationDate="2016-02-06T17:59:16.650" Score="6" Body="&lt;p&gt;The mid wing is mostly used in combat aircraft and rarely in passenger jets. The reasons are mostly structural.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Aerodynamically, the mid wing is the best option as it is much more streamlined and has less interference drag compared to the high and low wings.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The mid-wing also has neutral roll stability, which is good from the prespective of combat and aerobatic aircraft as it allows for the performance of rapid roll maneuvers with minimum yaw coupling.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The mid wing has certain disadvantages when it comes to structural design as far as passenger and cargo aircraft are concerned- the wing will have to either pass through the fuselage, eating into usable volume or the structure has to be strengthened around the fuselage to carry the loads. This is the main reason this type of wing is rarely found in commercial airliners.&lt;/p&gt;&#xA;&lt;p&gt;There are some aircraft which do have mid mountedwings, like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Piaggio_P.180_Avanti&quot; rel=&quot;noreferrer&quot;&gt;Piaggio Avanti&lt;/a&gt;, which has the wings passing behind the cabin and canards and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Hamburger_Flugzeugbau_HFB-320_Hansa_Jet&quot; rel=&quot;noreferrer&quot;&gt;Hansa jat&lt;/a&gt;, which solved the problem by sweeping the wings forward and thus passing it through the rear fuselage. These types are rare, however.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iSGe7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iSGe7.jpg&quot; alt=&quot;Hansa&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from hansajet.de&lt;/p&gt;&#xA;&lt;p&gt;This type of wings are used by a number of combat aircraft, however, for example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;noreferrer&quot;&gt;Dassault Rafale&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sRjYe.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sRjYe.jpg&quot; alt=&quot;Rafale&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://indiandefence.com&quot; rel=&quot;noreferrer&quot;&gt;http://indiandefence.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;For combat aircraft, the adoption of mid wings means that the landing gear have to retract into the fuselage for keeping the length under check. The mid wing allows for the carriage of weapons and fuel tanks in underwing pylons however. Also, the pilot's visibility is not affected during turns as in the case of high wing.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-06T17:59:16.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24978" PostTypeId="1" AcceptedAnswerId="24996" CreationDate="2016-02-06T20:02:28.623" Score="7" ViewCount="3051" Body="&lt;p&gt;If the load is heavier than a single helicopter could lift, how possible is to use multiple helicopters for this task?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have only seen this in some movies. The biggest doubts are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If we attach two ropes to the single point of the load in a V shaped way, a side force will be created pulling the helicopters together into collision.&lt;/li&gt;&#xA;&lt;li&gt;Even without this, the flight of the two machines probably needs to be very coordinated.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In movies like &quot;Pacific Rim&quot; a whole swarm of helicopters lift a heavy robot. How realistic are these visions?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="1696" LastEditDate="2016-06-14T16:51:20.820" LastActivityDate="2016-06-16T18:13:08.507" Title="Can multiple helicopters be used to lift a heavy load?" Tags="&lt;helicopter&gt;&lt;payload&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24979" PostTypeId="2" ParentId="24978" CreationDate="2016-02-06T20:33:27.417" Score="8" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=tkLOqAjMJmE&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;Dual Helicopter Lift&quot;&gt;This video&lt;/a&gt; on YouTube apparently shows that it has been done at least once. A rigid beam was used to counter the forces that would draw the two helicopters together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Screen grab:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eRgCd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eRgCd.jpg&quot; alt=&quot;Screen Grab&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also found &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/743516.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this fascinating report&lt;/a&gt; (.PDF link) from Piasecki (now part of Boeing Defense, Space &amp;amp; Security) that studied the feasibility of attaching two CH-53D helicopters to each other, including interconnected powerplants and flight controls!&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-02-06T20:41:54.917" LastActivityDate="2016-02-06T20:41:54.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24980" PostTypeId="2" ParentId="24973" CreationDate="2016-02-06T20:41:16.170" Score="6" Body="&lt;p&gt;A mid wing design is mostly used on aerobatic and combat aircraft. The wing spar carry-through would be where the payload needs to be in transport and passenger aircraft, so a mid wing is the worst choice for these types of aircraft. When Boeing turned the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-29_Superfortress&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-29&lt;/a&gt; into an airliner (the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_377_Stratocruiser&quot; rel=&quot;nofollow noreferrer&quot;&gt;377 Stratocruiser&lt;/a&gt;), they needed to &lt;a href=&quot;https://aviation.stackexchange.com/questions/21523/why-is-the-fuselage-on-an-airliner-circular-shaped/21525?s=2%7C0.0941#21525&quot;&gt;add a second tube&lt;/a&gt; on top of the original fuselage, turning a mid-wing design into a low-wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FTQwp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FTQwp.jpg&quot; alt=&quot;Boeing 377 Stratocruiser&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 377 Stratocruiser (picture &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/6/7/4/1961476.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Aerodynamic pros and cons&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pro: A mid wing position adds the least amount of interference drag. This is the main reason for using it on high-performance gliders.&lt;/li&gt;&#xA;&lt;li&gt;Pro: Ground effect is less than for a low-wing layout …&lt;/li&gt;&#xA;&lt;li&gt;Con: … but higher than for a high wing design.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Structural pros and cons&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pro: Puts the wing spar at the widest point of the fuselage cross section, so the load transfer is straightforward and the bulkheads can be lightweight, if no engines are in the way.&lt;/li&gt;&#xA;&lt;li&gt;Pro: Leaves more space for wing-mounted ordnance or engines and allows a shorter fuselage-mounted landing gear …&lt;/li&gt;&#xA;&lt;li&gt;Con: … but if the landing gear is wing-mounted, it needs to be longer and heavier than that of a low-wing configuration.&lt;/li&gt;&#xA;&lt;li&gt;Con: In fighter jets with fuselage-mounted engines the air ducts and engines are in the way of the wing spar, so it needs to be built around the intake duct(s) and engine(s). This makes the bulkheads heavy.&lt;/li&gt;&#xA;&lt;li&gt;Con: The spar will be where the payload needs to be in transport and passenger aircraft. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Flight characteristics pros and cons:&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pro: The inertial axes run through the center of the airplane, so any roll maneuvers can be performed quickly and without much change in the flight characteristics between upright and inverted flight. Note that most high-performance aerobatic airplanes use this layout.&lt;/li&gt;&#xA;&lt;li&gt;Con: In single- and tandem seaters with a cockpit close to the CG the wing blocks much of the pilot's view in the lower forward region, which makes take-offs and especially landings harder.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lLlgN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lLlgN.jpg&quot; alt=&quot;Patty Wagstaff&amp;#39;s Extra 300 over Florida&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Patty Wagstaff's Extra 300 over Florida (picture &lt;a href=&quot;http://media-cache-ak0.pinimg.com/736x/98/ad/f2/98adf2ff22e02f75e70ba5789e86c6f5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-07T11:34:27.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24981" PostTypeId="1" CreationDate="2016-02-06T20:53:17.117" Score="4" ViewCount="893" Body="&lt;p&gt;For young people interested in air traffic control careers with the FAA and who view military service as providing a boost toward that goal, which branches are most and least likely to get them there? In other words, how do the branches of the U.S. armed forces compare by headcount of ATC specialists working for the FAA? &lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-02-07T16:00:53.443" LastActivityDate="2019-04-10T17:01:45.280" Title="What is the breakout by service branch for FAA ATC specialists with military backgrounds?" Tags="&lt;air-traffic-control&gt;&lt;military&gt;&lt;faa&gt;&lt;career&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24982" PostTypeId="2" ParentId="24956" CreationDate="2016-02-06T21:21:13.113" Score="2" Body="&lt;p&gt;I doubt there is a worldwide statistics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accidents, where actual fire broke and did cause significant damage will be well known and listed on the &lt;a href=&quot;http://aviation-safety.net/database/events/event.php?code=FI&quot; rel=&quot;nofollow&quot;&gt;aviation safety network&lt;/a&gt;. However the precautionary evacuations that turned out to be false alarms and when nobody was seriously injured may fall through the cracks and not get reported anywhere. They &lt;em&gt;should&lt;/em&gt; be reported to the overseeing safety board and that &lt;em&gt;usually&lt;/em&gt; publishes at least summary list, but the system works better in some countries and less in other [&lt;a href=&quot;http://avherald.com/h?article=45483425&quot; rel=&quot;nofollow&quot;&gt;1&lt;/a&gt;]. And there is no central store for these reports in either case, so you could try to collect the numbers for one country (according to [&lt;a href=&quot;http://avherald.com/h?article=45483425&quot; rel=&quot;nofollow&quot;&gt;1&lt;/a&gt;], the reports are probably most complete for Canada), but that will be too few cases for decent statistics and worldwide data will be incomplete to the point of being useless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I am pretty sure the balancing is right. Not only do fires happen, but when they do, they are &lt;em&gt;fast&lt;/em&gt;. The &lt;a href=&quot;http://avherald.com/h?article=3f8fb20e&quot; rel=&quot;nofollow&quot;&gt;China Airlines flight 120 at Okinawa on Aug. 20th 2007&lt;/a&gt; burnt down in about 5 minutes. The first explosion occurred just few seconds after the last passenger left the plane and while the flight crew was evacuating. So if they waited any longer, it is quite likely someone would have died.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast most evacuations don't result in injuries and the few cases are mostly bruises, some sprained ankles and if someone has really bad luck, some broken leg or hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The broken bones (and not sure, but I think even the sprained ankles) count as serious injuries. So that's the options the captain is comparing. If they command evacuation, somebody &lt;em&gt;might break a leg&lt;/em&gt;, but if they don't &lt;em&gt;and the fire is real&lt;/em&gt;, somebody &lt;em&gt;&lt;strong&gt;will&lt;/strong&gt; die&lt;/em&gt;. And they must decide in couple of seconds for the evacuation to be successful. So they would obviously err on the side of caution and command the evacuation if they have a good reason to think there might be a fire.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-02-06T21:21:13.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24983" PostTypeId="1" AcceptedAnswerId="24984" CreationDate="2016-02-06T22:43:39.120" Score="8" ViewCount="1336" Body="&lt;p&gt;There are some &amp;quot;markings&amp;quot; over the wings and the horizontal stabilizer. Could somebody explain what they are?&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/y0CGv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/y0CGv.jpg&quot; alt=&quot;a380&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-07T13:59:35.713" Title="What are these markings on the A380 wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24984" PostTypeId="2" ParentId="24983" CreationDate="2016-02-06T23:05:58.170" Score="13" Body="&lt;p&gt;The darker areas denote where it is safe to step. Stepping outside of these areas could cause damage to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a closeup of the warning:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ExHwm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ExHwm.jpg&quot; alt=&quot;Quantas Flight 32 Wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This happens to be a photo of &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_32&quot; rel=&quot;nofollow noreferrer&quot;&gt;Qantas Flight 32&lt;/a&gt; after its un-contained engine failure)&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-02-06T23:19:57.873" LastActivityDate="2016-02-06T23:19:57.873" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="24985" PostTypeId="1" AcceptedAnswerId="24986" CreationDate="2016-02-06T23:18:38.793" Score="7" ViewCount="2012" Body="&lt;p&gt;If an airplane receives a 100 hour at 350 hours and has an annual at 400 hours, does the next 100 hour inspection need to take place at 450 hours or 500 hours?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="9491" LastEditDate="2016-02-07T03:05:41.043" LastActivityDate="2016-02-07T03:05:41.043" Title="Does a 100 Hour Inspection Start Over Every Annual?" Tags="&lt;faa-regulations&gt;&lt;airworthiness&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24986" PostTypeId="2" ParentId="24985" CreationDate="2016-02-07T00:16:51.523" Score="6" Body="&lt;p&gt;The annual will reset the 100 hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&amp;amp;SID=1454781a31ab227ba05604c523261622&amp;amp;ty=HTML&amp;amp;h=L&amp;amp;mc=true&amp;amp;r=SECTION&amp;amp;n=se14.2.91_1409&quot;&gt;91.409&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Except as provided in paragraph (c) of this section, no person may operate an aircraft carrying any person (other than a crewmember) for hire, and no person may give flight instruction for hire in an aircraft which that person provides, unless within the preceding 100 hours of time in service the aircraft has &lt;strong&gt;received an annual or 100-hour inspection&lt;/strong&gt; and been approved for return to service in accordance with part 43 of this chapter or has received an inspection for the issuance of an airworthiness certificate in accordance with part 21 of this chapter. The 100-hour limitation may be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done. The excess time used to reach a place where the inspection can be done must be included in computing the next 100 hours of time in service.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-07T00:16:51.523" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24987" PostTypeId="1" AcceptedAnswerId="24988" CreationDate="2016-02-07T01:48:10.783" Score="15" ViewCount="1645" Body="&lt;p&gt;There are some red windows on the 737 and the CS-300 as well. Why are they painted red?&lt;br&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Boeing/Boeing-737-8-Max/2771977/M/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/UlE9S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UlE9S.jpg&quot; alt=&quot;7378&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WO15W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WO15W.jpg&quot; alt=&quot;cs100&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://marriott.airliners.net/photo/Bombardier/Bombardier-CSeries-CS300/2659427/L/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:38:54.723" LastActivityDate="2016-03-05T17:38:54.723" Title="Why are these windows on some airplanes red?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;windows&gt;&lt;flight-testing&gt;&lt;airbus-a220&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24988" PostTypeId="2" ParentId="24987" CreationDate="2016-02-07T02:06:31.407" Score="21" Body="&lt;p&gt;A red/orange color is typically used to denote flight test instrumentation. Indeed, these windows do contain such instrumentation. Below you can see a similar window on a 747-8I flight test aircraft (note the 7th window from the nose):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0h7tr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0h7tr.jpg&quot; alt=&quot;747-8I&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the corresponding inside view:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8NZOR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8NZOR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-02-07T02:12:20.677" LastActivityDate="2016-02-07T02:12:20.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24989" PostTypeId="2" ParentId="24987" CreationDate="2016-02-07T02:13:27.207" Score="12" Body="&lt;p&gt;The aircrafts shown above are test aircraft and the windows are blanked for mounting test instrument. The image below shows the inside of Bombardier C-series test aircraft, which shows the mounting of test equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jFnS8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jFnS8.jpg&quot; alt=&quot;C100&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airwaysnews.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the screengrab below from &lt;a href=&quot;https://www.youtube.com/watch?v=edrbbwhW0Cw&quot; rel=&quot;noreferrer&quot;&gt;this video about C series testing&lt;/a&gt; shows the interior of the C series test aircraft with blanked windows with attached instrumentation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/H3p4n.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H3p4n.jpg&quot; alt=&quot;C series test&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, see &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/print.main?id=133643&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; thread that discusses about the same thing. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-02-07T02:24:27.253" LastActivityDate="2016-02-07T02:24:27.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24990" PostTypeId="1" AcceptedAnswerId="24994" CreationDate="2016-02-07T02:51:03.427" Score="4" ViewCount="698" Body="&lt;p&gt;Below is a screen grab from the &lt;a href=&quot;http://www.ais.gov.hk/HK_AIP/AIP/AD/HK_AD2-94A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS RWY 25R approach chart&lt;/a&gt; for HKG/VHHH. What should the plane do after passing SMT radial 084 (or TD D8 NM)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't look like immediately turn heading 253 degrees; from an algorithmic point of view does the plane do an RNAV from PLOVE to RIVER, then track SMT radial 253 after RIVER? Or does it start to track SMT 253 right after SMT radial 084?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, what does &quot;ITFR&quot; stand for in this graph? The ITFR distance measures from the east and west side of the runway are based on two different ILS localizers, is that correct? Thanks!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vMgF1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vMgF1.jpg&quot; alt=&quot;VHHH ILS RWY 25R&quot;&gt;&lt;/a&gt;&#xA;(Source: AD 2-94A, Aeronautical Information Publication, Hong Kong Aeronautical Information Services)&lt;/p&gt;&#xA;" OwnerDisplayName="user13377" LastEditorDisplayName="user13377" LastEditDate="2016-02-07T03:21:48.273" LastActivityDate="2016-02-07T03:48:00.390" Title="(See Included ILS Chart) What to Do After SMT RDL 084?" Tags="&lt;air-traffic-control&gt;&lt;approach&gt;&lt;aeronautical-charts&gt;&lt;ils&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24991" PostTypeId="5" CreationDate="2016-02-07T03:01:34.097" Score="0" Body="&lt;p&gt;The Bombardier CSeries CS100 and CS300 jet airliners were designed by Bombardier Aerospace to compete with the Boeing 737 and the Airbus A320 in the short- to medium-range narrow-body/single-aisle range.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CSeries&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bombardier CSeries&lt;/a&gt; (Wikipedia)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2017-11-29T19:19:18.717" LastActivityDate="2017-11-29T19:19:18.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24992" PostTypeId="4" CreationDate="2016-02-07T03:01:34.097" Score="0" Body="A single-aisle short- to medium-range commercial jet airliner created by Bombardier Aerospace." OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2017-11-29T19:19:18.717" LastActivityDate="2017-11-29T19:19:18.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24993" PostTypeId="1" AcceptedAnswerId="24998" CreationDate="2016-02-07T03:43:06.530" Score="28" ViewCount="2873" Body="&lt;p&gt;Yesterday I flew from San Diego to Boston in a commercial 737 operated by Alaska Airlines. Before landing we spent almost an hour circling. When we finally landed, many passengers were surprised to learn that we were not in Boston; we were still 90 miles / 150 km away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight attendants told us the pilots had been too busy to announce the diversion. When the captain finally made an announcement on the ground, he said we had been redirected because the wait for Boston was 60 minutes and &lt;b&gt;&quot;we only had about 10 minutes of fuel left.&quot;&lt;/b&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cause was snow in Boston. Many flights were cancelled. However, visibility was excellent where we were and the flight was smooth. So I was surprised that we were diverted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://flightaware.com/live/flight/ASA798/history/20160205/1635Z/KSAN/KBDL/tracklog&quot; rel=&quot;noreferrer&quot;&gt;flightaware&lt;/a&gt;, we started circling at approximately 4pm; we were diverted at 4:48pm and landed at BDL at 5:03pm. Our scheduled arrival time was 5:06pm. (We departed on time.) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is the flight path (&lt;a href=&quot;https://flightaware.com/live/flight/ASA798/history/20160205/1635Z/KSAN/KBDL&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;a href=&quot;https://i.stack.imgur.com/FHDNz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FHDNz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was hoping that some people more knowledgeable than myself could help me better understand what was going on.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Does &quot;10 minutes of fuel left&quot; mean 10 minutes until empty or 10 minutes until it becomes urgent? I find it hard to believe that there was so little reserve fuel, especially given that we were in the air for the scheduled amount of time.&lt;/li&gt;&#xA;&lt;li&gt;Would this situation count as a fuel emergency? Was it comparable to &lt;a href=&quot;http://www.tampabay.com/news/business/airlines/allegiant-air-flight-runs-low-on-fuel-over-closed-airport-makes-emergency/2238936&quot; rel=&quot;noreferrer&quot;&gt;this incident&lt;/a&gt;?&lt;/li&gt;&#xA;&lt;li&gt;How low do commercial jets normally go fuel wise? In particular, how common is it to have 10 minutes of fuel left when landing?&lt;/li&gt;&#xA;&lt;li&gt;Can I find out more information about my flight online? I only know of flightaware. Is it possible to find ATC radio recordings?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11476" LastEditorUserId="12220" LastEditDate="2016-02-07T20:26:51.230" LastActivityDate="2016-02-07T20:26:51.230" Title="Was this flight a fuel emergency?" Tags="&lt;fuel&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="24994" PostTypeId="2" ParentId="24990" CreationDate="2016-02-07T03:48:00.390" Score="5" Body="&lt;p&gt;SMT RDL 084 is simply a &lt;a href=&quot;https://aviation.stackexchange.com/a/2440/69&quot;&gt;lead radial&lt;/a&gt;, so it is there to let you know when to start your turn so that you can intercept the SIU 253 course without overshooting it during the turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just below and to the left of the airport is the box which shows the ILS frequency.  It tells us that the DME identifier for this ILS is ITFR, so the distances are provided based on the distance from the DME transmitter associated with the ILS.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-02-07T03:48:00.390" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="24996" PostTypeId="2" ParentId="24978" CreationDate="2016-02-07T04:55:17.360" Score="4" Body="&lt;p&gt;Yes, this is possible, as demonstrated in this video from almost 2 years ago:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=77uK19KxMuI&quot; rel=&quot;nofollow&quot;&gt;Video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Each helicopter probably does not weigh more than the woman being lifted.&lt;/li&gt;&#xA;&lt;li&gt;The two helicopters are tilted such that the forces are in equilibrium with no collisions.&lt;/li&gt;&#xA;&lt;li&gt;Both are coordinated as two pilots are flying these by Line-of-Sight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13379" LastActivityDate="2016-02-07T04:55:17.360" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="24997" PostTypeId="2" ParentId="24993" CreationDate="2016-02-07T05:26:26.163" Score="19" Body="&lt;p&gt;I feel like this was just a poor choice of wording by the captain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is extremely rare for an aircraft to land with just 10 minutes of fuel remaining, though &lt;a href=&quot;http://www.traveller.com.au/virgin-australia-plane-in-fuel-emergency-at-mildura-airport-2q6e7&quot;&gt;it has happened before&lt;/a&gt;. In most cases, a jet needs to land with at least 30 minutes of fuel in the tanks, plus a variable percentage on top depending on the trip length - plus the airline-specific Ops Specs may require even more, and sometimes a specific airport warrants extra fuel for holding purposes. If the weather doesn't look too good, the plane needs to carry even more fuel to reach another airport, without using these minimums.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I suspect the pilot meant he had 10 minutes of holding time, before he would have dipped into these minimums. Doing so is a big no-no and the authorities will need to be notified, hence the diversion before that happened. If my suspicion is correct, this did not count as an emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your last question, liveatc.net is where you can find most ATC recordings. And if I am wrong and the pilot meant there was 10 minutes of fuel in the tanks, you should see the details on avherald.com soon! &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-02-07T05:26:26.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="24998" PostTypeId="2" ParentId="24993" CreationDate="2016-02-07T05:42:32.280" Score="23" Body="&lt;p&gt;There appears to be no emergency. The flight was diverted at 16:58 EST and landed at Bradley International Airport at 17:03 EST. The &lt;a href=&quot;https://uk.flightaware.com/live/flight/ASA798/history/20160206/1635Z/KSAN/KBOS/tracklog&quot; rel=&quot;noreferrer&quot;&gt;same flight on 6th Feb&lt;/a&gt; landed at Boston at 16:46 EST. So basically, the flight was in the air only for an extra 15 minutes, compared to the scheduled time.&lt;/p&gt;&#xA;&lt;p&gt;According to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/121.639&quot; rel=&quot;noreferrer&quot;&gt;§ 121.639 Fuel supply: All domestic operations.&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No person may dispatch or take off an airplane unless it has enough fuel—&lt;/p&gt;&#xA;&lt;p&gt;(a) To fly to the airport to which it is dispatched;&lt;/p&gt;&#xA;&lt;p&gt;(b) Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and&lt;/p&gt;&#xA;&lt;p&gt;(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So basically, the pilot diverted because the holding time was another 60 minutes and that would've eaten into fuel reserves.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;I think the captain meant that the aircraft had only 10 minutes of fuel till he had to dip into reserves (or fly the alternate- it depends) and diverted &lt;em&gt;because of the 60 minute waiting time&lt;/em&gt;. He could've been more clear though.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The pilot would've declared a fuel emergency if there was one. So, I think there was none.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Its quite uncommon for aircraft to land on 10 minutes &lt;em&gt;of reserve fuel&lt;/em&gt;, though it has happened. In fact, some aircraft have run out of fuel.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You can find details about the ATC in &lt;a href=&quot;http://www.liveatc.net/archive.php&quot; rel=&quot;noreferrer&quot;&gt;liveatc's audio archives&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-07T05:42:32.280" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25000" PostTypeId="1" CreationDate="2016-02-07T08:00:58.180" Score="12" ViewCount="1648" Body="&lt;p&gt;Are aircraft used for flight testing typically sold to Airline customers after their use for flight testing is over? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. The aircraft shown in this SE Aviation Question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/24987/why-are-these-windows-on-some-airplanes-red&quot;&gt;Why are these windows on some airplanes red?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sounds like a lot of money to waste so I expect they would be sold for some revenue but to what end use is the question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WO15W.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WO15W.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-26T06:44:41.953" Title="What happens to Flight Testing Aircraft after Testing is over?" Tags="&lt;commercial-aviation&gt;&lt;flight-testing&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25001" PostTypeId="1" AcceptedAnswerId="25002" CreationDate="2016-02-07T08:08:25.843" Score="9" ViewCount="2387" Body="&lt;p&gt;Every airport I have encountered has flat runways and taxiways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course this is not exactly true, as some other questions picked up, and it is also possible that I just happened to visit mostly flat airports. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any specification for maximum slope gradient an aircraft can safely taxi on?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A slope could be useful if an airport wanted to build an airplane bridge for example. &lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="19" LastEditDate="2016-07-11T08:37:25.540" LastActivityDate="2016-07-11T08:37:25.540" Title="What is the maximum slope for taxiing aircraft?" Tags="&lt;regulations&gt;&lt;taxiing&gt;&lt;airport-design&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25002" PostTypeId="2" ParentId="25001" CreationDate="2016-02-07T09:14:20.413" Score="10" Body="&lt;p&gt;&lt;sub&gt;Footnote: I hope this is the correct/ current regulation. Published date is 25 January 2015.&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your question is covered (for EASA regulations) in the document &lt;em&gt;Certification Specifications and Guidance Material for Aerodromes Design&lt;/em&gt; (&lt;a href=&quot;https://www.easa.europa.eu/system/files/dfu/CS-ADR-DSN%20%20Issue%202%20to%20EDD%202015-001-R%20v1%20%28corrected%29.pdf&quot;&gt;link&lt;/a&gt;) in two sections: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Taxiway Slope (CS ADR-DSN.D.265)&lt;/li&gt;&#xA;&lt;li&gt;Taxiway Slope changes (CS ADR-DSN.D.270)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;CS ADR-DSN.D.265 Longitudinal slopes on taxiways&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The safety objective of limiting the longitudinal taxiway slope&#xA;  is to enable stabilised safe use of taxiway by an aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The longitudinal slope of a taxiway should not exceed:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;1.5% where the code letter is C, D, E, or F; and&lt;/li&gt;&#xA;  &lt;li&gt;3% where the code letter is A or B.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;CS ADR-DSN.D.270 Longitudinal slope changes on taxiways&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) The safety objective of limiting the longitudinal taxiway slope&#xA;  changes is to avoid damage of aircraft and to enable safe use of&#xA;  taxiway by an aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Where slope changes on a taxiway cannot be avoided, the transition&#xA;  from one slope to another slope should be accomplished by a curved&#xA;  surface with a rate of change not exceeding:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;1% per 30m (minimum radius of curvature of 3000m) where the code letter is C, D, E,or F; and&lt;/li&gt;&#xA;  &lt;li&gt;1% per 25m (minimum radius of curvature of 2500m) where the code letter is A or B.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;(c) Where slope changes in (b)(1) and (2)  are not  achieved and&#xA;  slopes on a taxiway cannot  be avoided, the  transition  from  one &#xA;  slope  to  another  slope  should  be  accomplished  by  a  curved &#xA;  surface  which  should allow the safe operation of all aircraft in all&#xA;  weather conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The letters refer to the &lt;a href=&quot;http://www.airfieldcharts.com/airportcategorisation.htm&quot;&gt;airport categorization&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2016-02-07T13:22:30.840" LastActivityDate="2016-02-07T13:22:30.840" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25003" PostTypeId="2" ParentId="25000" CreationDate="2016-02-07T09:43:02.600" Score="8" Body="&lt;p&gt;It depends. In most of the cases, the aircraft have been instrumented and pushed so much that it not possible to modify them for commercial flight. In these cases, they are either preserved or continued to be used as test aircraft. In other cases, the aircraft are modified and delivered. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://q13fox.com/2014/09/09/first-boeing-747-ever-built-under-restoration/&quot; rel=&quot;noreferrer&quot;&gt;Boeing 747&lt;/a&gt;- The first ever Boeing 747 was used exclusively as a test aircraft and was later handed over to museum. On the other hand &lt;a href=&quot;https://www.planespotters.net/production-list/Boeing/787/787-8&quot; rel=&quot;noreferrer&quot;&gt;all the 747-8&lt;/a&gt;s were converted back after test flights and delivered to customers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.planespotters.net/production-list/Boeing/777/777-200&quot; rel=&quot;noreferrer&quot;&gt;Boeing 777&lt;/a&gt;- The first 777s were &lt;a href=&quot;http://www.kls2.com/cgi-bin/arcfetch?db=sci.aeronautics.airliners&amp;amp;id=%3Cairliners.1997.2815@ohare.chicago.com%3E&quot; rel=&quot;noreferrer&quot;&gt;considered production models&lt;/a&gt;, not prototypes and were delivered to customers after testing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.planespotters.net/production-list/Boeing/787/787-8&quot; rel=&quot;noreferrer&quot;&gt;Boeing 787&lt;/a&gt;- It is kind of a mixed bag here- The first three 787s are in museums across the world (two in the US, one in Japan). Boeing is still using one as a testbed, while one more is in storage. Another aircraft used for testing was later modified and sold to the Mexican Air Force.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.planespotters.net/production-list/Airbus/A350&quot; rel=&quot;noreferrer&quot;&gt;Airbus A350XWB&lt;/a&gt;- Right now, Airbus is holding &lt;a href=&quot;http://www.airbus.com/company/aircraft-manufacture/how-is-an-aircraft-built/test-programme-and-certification/&quot; rel=&quot;noreferrer&quot;&gt;all the five&lt;/a&gt; testing aircraft and using them for testing or demonstration flights.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;https://www.planespotters.net/production-list/Airbus/A380&quot; rel=&quot;noreferrer&quot;&gt;Airbus A380&lt;/a&gt;- Airbus has all the test aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can check out the production lists of various aircraft &lt;a href=&quot;https://www.planespotters.net/production-list/index&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3313" LastEditDate="2016-02-07T13:54:51.253" LastActivityDate="2016-02-07T13:54:51.253" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25004" PostTypeId="2" ParentId="25000" CreationDate="2016-02-07T09:44:10.077" Score="6" Body="&lt;p&gt;Prototype aircraft are generally of less value than the production counterparts, since they are heavier and may not have the normal design configuration.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 737: The original -100 ended up going to NASA as a research aircraft as NASA 515.&lt;/li&gt;&#xA;&lt;li&gt;Boeing 747: At the Museum of Flight.&lt;/li&gt;&#xA;&lt;li&gt;Boeing 757: Nicknamed &quot;Catfish&quot;, it is an experimental avionics testbed registered N757A.&lt;/li&gt;&#xA;&lt;li&gt;Airbus A320: One retained and continued to be used for the type's winglet/engine testing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Particularly new aircraft (and derivatives thereof) tend to go to customers as testing becomes more refined and the cause of less design changes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Boeing 737-800 prototype went to commercial service, now operating as TC-SNY.&lt;/li&gt;&#xA;&lt;li&gt;Boeing 737-900 prototype went to Alaska Airlines as N302AS&lt;/li&gt;&#xA;&lt;li&gt;Boeing 777-200 prototype went to Cathay Pacific as B-HNL.&lt;/li&gt;&#xA;&lt;li&gt;Boeing 777-200LR prototype went to Pakistan International Airlines as AP-BGY&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, not every aircraft can be sold if the aircraft is too unattractive and end up in a museum so many have been scrapped.&lt;/p&gt;&#xA;" OwnerUserId="790" LastEditorUserId="790" LastEditDate="2016-02-07T09:57:15.120" LastActivityDate="2016-02-07T09:57:15.120" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25005" PostTypeId="2" ParentId="25000" CreationDate="2016-02-07T10:01:58.537" Score="2" Body="&lt;p&gt;In order to reduce the certification time needed, manufacturers usually manufacture more than one testing aircraft, this way several flight tests can be done in parallel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the airplane is finished, keeping those airplanes is a cost and there is no business case to keep all them. However, an airplane model is a living design and during its lifetime (could be more than 50 years, as B737 for example) the airplane design will be updated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things as simple as obsolescence of equipments, small improvements, new technologies... not just re-engining the airplane. Those modifications must be certified as well, and some of the means of compliance require a flight test.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in this context:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Manufacturer usually keeps always one of each airplane model, and likely more than one during a period of time.&lt;/li&gt;&#xA;&lt;li&gt;Those having less damages and usable for commercial flights (like long haul testing) are usually sold with a discount (and actually very early...)&lt;/li&gt;&#xA;&lt;li&gt;Finally, those that are too expensive to keep and not usable for commercial flight are scrapped or sold/donated to institutions.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Anyhow, is a significant amount of money what is lost, but is part of the development cost. Finally is a business case... you can extend the certification period by 1 year and save 2 testing airplanes? Having 1 year more the manufacturing line stopped waiting for the certification? Finally using several testing airplane is a possitive business case.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastActivityDate="2016-02-07T10:01:58.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25007" PostTypeId="1" CreationDate="2016-02-07T13:15:36.227" Score="4" ViewCount="131" Body="&lt;p&gt;Air density at lower altitudes is higher, and thus provides more resistance to objects moving through it. Is this higher density enough to &lt;em&gt;practically&lt;/em&gt; impact the fuel efficiency of an aircraft flying at low altitudes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if a B777 enters a holding pattern for 60 minutes just outside an airport at maybe 5,000', is it going to burn significantly more fuel than if it had (for whatever reason) entered the same holding pattern in the middle of cruising at 40,000'?&lt;/p&gt;&#xA;" OwnerUserId="856" LastActivityDate="2016-02-07T13:15:36.227" Title="Do airliners use more fuel at low altitude than high altitude?" Tags="&lt;airliner&gt;&lt;efficiency&gt;&lt;holding&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-02-07T14:21:08.570" ContentLicense="CC BY-SA 3.0" />
  <row Id="25008" PostTypeId="1" AcceptedAnswerId="25011" CreationDate="2016-02-07T14:09:13.530" Score="11" ViewCount="7705" Body="&lt;p&gt;I mean why using Krueger flaps in some aircraft instead of using slats all over the leading edge?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-02-08T21:30:32.053" Title="What are the benefits of using Krueger Flaps?" Tags="&lt;aircraft-design&gt;&lt;flaps&gt;&lt;slats&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25009" PostTypeId="2" ParentId="25008" CreationDate="2016-02-07T14:19:12.480" Score="4" Body="&lt;p&gt;Many large airliners, particularly Boeings, use Krueger flaps closer in to the fuselage and slats further out on the wing. This is primarily because slats resist a stall more effectively, so by placing Krueger flaps on the forward parts on a swept wing and slats on the rearward sections, it encourages a more balanced, controlled landing stall. Another reason to use Krueger flaps is that they are lighter, both with the equipment itself and with its actuators, and can be used on thinner wings that are too thin for slats.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="13371" LastEditDate="2016-02-07T15:46:05.973" LastActivityDate="2016-02-07T15:46:05.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25010" PostTypeId="1" AcceptedAnswerId="25025" CreationDate="2016-02-07T16:00:27.253" Score="12" ViewCount="847" Body="&lt;p&gt;Note: I'm by no means an expert on any of this, I'm just curious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There seems to be a general trend toward higher and higher bypass ratios in commercial jetliner engines. (I'm thinking here of 737/A320-size and larger aircraft.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand why this is happening (fuel-efficiency &amp;amp; noise). But what has dictated the odd pace of the development?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was obviously a drive toward higher bypass early on. E.g. P&amp;amp;W JT8D engines introduced in 1962 ran at 0.96:1, while - just a few years later in 1966 - the JT9D ran at 5:1. Quite a leap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then it seems to me that it settled around 5-6:1 for 25 years. Next big leap seems to be the GE90 in which runs at 9:1. That was 1992 and then it largely settled again at 9-10:1 for another couple of decades. The latest (smaller) leap appears to be the PW1000G at 12:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What has caused such sudden jumps and plateaus? Why hasn't there either been a more linear progression from the 1960s to now? Or a much faster progression toward the ratios we see today? They're obviously desirable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can just imagine P&amp;amp;W engineers looking at the JT9D in the mid-1960s, and thinking &quot;well, we went from 1:1 to 5:1 in one go. Let's go for 10:1 next!&quot;. But that didn't happen. It seems their next major airliner engine was the PW2000 - fully 20 years later - at 6:1.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Was it due to technical/manufacturing limitations?&lt;/li&gt;&#xA;&lt;li&gt;Has the emphasis on certain performance characteristics shifted? E.g. settling more permanently on economy over speed.&lt;/li&gt;&#xA;&lt;li&gt;Is it simply that fleets stabilized around certain aircraft, and no new engines were needed/wanted for a long time?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The last point seems very plausible. Even so, the 747-8, 737-MAX and A320neo, while being comparable to their ancestors in size and role, have made sudden jumps from 5-6:1 to 10-12:1 engines. That feels like something that could conceivably have happened earlier or more gradually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course I know that bypass ratio isn't the &lt;em&gt;only&lt;/em&gt; interesting metric for an engine, but it's a noticeable one, even to the untrained eye; engines are simply becoming bigger and bigger. But that's also why I'm asking about the pace of development, since &quot;making the fan bigger&quot; seems like an obvious step to take (I know there's more to it but still). It also seems like something that'd be more likely to happen gradually, rather than in spurts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, I'm no expert, I've just been googling. But I may have missed something basic.&lt;/p&gt;&#xA;" OwnerUserId="13218" LastEditorUserId="13218" LastEditDate="2016-02-07T23:35:46.900" LastActivityDate="2016-04-14T14:58:02.717" Title="What drives and/or allows the move to higher-bypass turbofans on jetliners?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;turbofan&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25011" PostTypeId="2" ParentId="25008" CreationDate="2016-02-07T16:12:21.323" Score="5" Body="&lt;p&gt;There are different types of Krueger flaps used, with increased efficiency coming at the cost of increased complexity.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The simple ones are basically flat panels that folds out from the wing lower surface into a very steep, deployed position and seals against the wing leading edge; though these are extremely simple, they don't offer much in the way of stall protection.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The next type has large folding 'bull' nose that offers increased performance at the cost of slightly increased complexity. This type of flaps is used in B727, B737, and inboard of B747, as shown in the figure below:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9epf7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9epf7.jpg&quot; alt=&quot;b747&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Arpingstone - Photographed by Adrian Pingstone in August 2002 and released to the public domain., Public Domain, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=118310&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=118310&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The most complex type of Krueger flaps are the variable camber type, which has a flexible panel (which forms a slot at the trailing edge) and a bull nose. This provides a better $C_{L_{max}}$ performance compared to a slat, but gives poorer takeoff L/D performance compared to the slat. However, the main problem is that the mechanism is exceptionally complex, as can be seen in the figure below. As a result not many aircraft use these.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/33gKk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/33gKk.jpg&quot; alt=&quot;Krueger flap&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://aviation.stackexchange.com/questions/14888/why-do-similar-airbus-and-boeing-aircraft-use-different-flap-and-slat-mechanisms&quot;&gt;aviation.stackexchange&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that simpler Krueger flaps are used in the inboard with slats in the outboard region, so that the flow remains attached in the outboard regions at higher angles of attack compared to the inboard region. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-02-08T21:30:32.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25012" PostTypeId="1" AcceptedAnswerId="25014" CreationDate="2016-02-07T16:22:18.150" Score="15" ViewCount="6895" Body="&lt;p&gt;I was flying from Heathrow to Miami last wednesday (&lt;a href=&quot;https://flightaware.com/live/flight/AAL39/history/20160203/1115Z/EGLL/KMIA&quot;&gt;AA 39&lt;/a&gt;) and for the first ⅔ of the flight we were flying at 28.000 feet, only afterwards did it go up to 33.000 feet. So far I was under the impression that for reasons of fuel efficiency, airliners would try to fly as high as possible, and looking at the same flight on different days, it seems like they do in fact usually fly higher. So what could have been the reason for such a low altitude? Was it just weight due to being fully loaded, or are there other reasons as well?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastEditorUserId="12720" LastEditDate="2016-02-07T18:45:14.097" LastActivityDate="2016-02-07T18:45:14.097" Title="What might have been the reasons for this low flight altitude?" Tags="&lt;flight-planning&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25013" PostTypeId="1" AcceptedAnswerId="25019" CreationDate="2016-02-07T16:32:28.453" Score="19" ViewCount="4416" Body="&lt;p&gt;The engines are always painted a certain colour but the front part is always grey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.m.wikimedia.org/wiki/File:737_CFM56_engine.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YFTgX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YFTgX.jpg&quot; alt=&quot;cfm56&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And here on the XWB:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/njydG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/njydG.jpg&quot; alt=&quot;xwb&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Rolls-Royce_Trent_XWB#/media/File%3ATrent_XWB_(14272089101)_(2).jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it that?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:34:45.500" LastActivityDate="2016-03-05T17:34:45.500" Title="Why is the front part of the engine not painted?" Tags="&lt;engine&gt;&lt;paint&gt;" AnswerCount="2" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="25014" PostTypeId="2" ParentId="25012" CreationDate="2016-02-07T16:49:01.560" Score="24" Body="&lt;p&gt;Looking at the route your plane took, this low altitude flight was likely to avoid the polar jetstream. This is a band of wind that blows west to east in roughly the area the first half of your flight was flying through. It exists mostly between 30,000 and 39,000 feet altitude, and can range from about 60mph to over 200mph. I suspect that the low altitude was to keep the plane below this jetstream, avoiding the headwind and fuel and time costs that flying through it would create. To answer the other part of your question, as I mentioned in the comments, weight shouldn't have been an issue because the plane you were in (a 777-300ER), has more than enough engine power to maintain a higher altitude, even fully weighted.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-02-07T16:49:01.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25015" PostTypeId="2" ParentId="25012" CreationDate="2016-02-07T16:53:45.730" Score="11" Body="&lt;p&gt;There are generally 3 reasons to pick lower altitudes:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;At departure your weight would be too much to climb to the desired altitude. Some aircraft are restricted by weight to get up to higher altitudes, usually a thrust-weight issue.&lt;/li&gt;&#xA;&lt;li&gt;Something's broken on the aircraft requiring it to fly at a lower altitude for safety reasons. As an example, the Air conditioning packs, that control the pressurization on an aircraft, if one is out, the flight might be restricted to a lower altitude so the system can handle the reduced output of the remaining packs to maintain a suitable pressure onboard.&lt;/li&gt;&#xA;&lt;li&gt;The most likely reason though in this case is to be at an altidude where the headwinds are less than what they are higher. Oftentimes the highest winds in the jetstream start in the FL300+ range, and run generally West-East. So trying to pick an optimal altitude is a factor of getting high enough for efficiency, but not to where you'll be losing that efficiency due to the higher winds aloft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-02-07T16:53:45.730" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25016" PostTypeId="1" AcceptedAnswerId="25018" CreationDate="2016-02-07T17:11:33.977" Score="9" ViewCount="1369" Body="&lt;p&gt;I don't find the horizontal stabilizers or the elevators of a Concorde at the tail section like other aircrafts. Are they fitted beside the ailerons in the wings?&lt;a href=&quot;https://i.stack.imgur.com/b8v8Q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b8v8Q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12871" LastEditorUserId="12871" LastEditDate="2016-02-11T18:42:59.073" LastActivityDate="2016-02-11T18:42:59.073" Title="Where are the locations of the elevators or horizontal stabilizers in a Concorde?" Tags="&lt;flight-controls&gt;&lt;flight-instruments&gt;&lt;concorde&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25017" PostTypeId="2" ParentId="25013" CreationDate="2016-02-07T17:11:46.633" Score="6" Body="&lt;p&gt;There are two reasons I can think of for this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Aerodynamic reasons. Believe it or not, even paint can change the dynamics of a plane, to the point that Boeing discourages  multi-colored paint jobs or liveries on 787 nacelle, claiming they affect performance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If that part of the engine were painted, there would be risk of paint chips being sucked into the engines, potentially damaging them. While this may seem far-fetched, &lt;a href=&quot;http://www.aviationpros.com/article/10374800/engine-forensics&quot;&gt;this &lt;/a&gt;account shows that even paint chips can pose a foreign object debris threat to an engine. By not painting this part of the nacelle, the risk of paint flecking off and into the engine is reduced.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-02-07T17:11:46.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25018" PostTypeId="2" ParentId="25016" CreationDate="2016-02-07T17:15:54.367" Score="13" Body="&lt;p&gt;There is no &quot;horizontal stabilizer&quot; on the Concorde like other commercial aircraft, the wing performs that duty because it is a delta-wing. The elevators for the Concorde are combined with the ailerons into something called &quot;elevons&quot; which perform both functions (Think stereotype paper airplane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: Elevators and Horizontal stabilizers are not the same thing. Most aircraft have their elevators located on their horizontal stabilizers, only a few have the whole stabilizer as an elevator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source &lt;a href=&quot;http://www.concordesst.com/wing.html&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-02-07T17:15:54.367" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25019" PostTypeId="2" ParentId="25013" CreationDate="2016-02-07T17:44:22.190" Score="32" Body="&lt;p&gt;The engine inlet lip is bare metal to facilitate anti-icing. The area is heated from within using hot engine bleed air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This partial schematic (from Boeing &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2012_q1/&quot; rel=&quot;noreferrer&quot;&gt;AERO QTR_01.12&lt;/a&gt;) shows the engine anti-ice valve, which controls the air supply to the inlet lip:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ebzYr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ebzYr.jpg&quot; alt=&quot;747-8 Engine Bleed Schematic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interesting side note: Even the 787 &quot;no-bleed&quot; system architecture uses bleed air for engine anti-ice.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-02-07T17:57:01.477" LastActivityDate="2016-02-07T17:57:01.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25020" PostTypeId="1" AcceptedAnswerId="25023" CreationDate="2016-02-07T20:27:26.260" Score="18" ViewCount="8077" Body="&lt;p&gt;What are these lines on the radome?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/o3uPB.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o3uPB.jpg&quot; alt=&quot;737 nose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see them here:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/442vh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/442vh.jpg&quot; alt=&quot;737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they and what is their function?&#xA;Source: &lt;a href=&quot;http://aviafilms.com/&quot; rel=&quot;noreferrer&quot;&gt;AviaFilms&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-24T22:59:12.400" LastActivityDate="2021-02-09T16:15:15.113" Title="What are these lines on the nose of a Boeing 737?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;boeing-737&gt;&lt;nose&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25023" PostTypeId="2" ParentId="25020" CreationDate="2016-02-07T21:35:42.230" Score="22" Body="&lt;p&gt;I'm no expert on B737 radomes, but I was able to find that these are called Lightning Diversion Strips or Lightning Diverter Strips.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since radomes are generally built with composites, they do not transmit static electricity in the same way that aluminum skin would.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The B737-200 maintenance manual states that the radome is constructed of fiberglass and is provided with lightning diverter strips on the outside surface—though it states that these are not necessarily provided on all airplanes. It further states that these diverter strips are constructed of thin gauge aluminum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.b737.org.uk/fuselage.htm#RADOME&quot;&gt;b737.org.uk&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The radome (RAdar DOME) is an aerodynamic faring that houses the weather radar and ILS localiser and glideslope antennas. Unlike the rest of the fuselage it is made of fibreglass to allow the RF signals through.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Fibreglass is non-conductive which would allow the build up of P-static (static due to the motion of the aircraft through precipitation). This would in turn cause static interference on the antenna within so the radome is fitted with six conductive diverter strips on the outside to dissipate P-static into the airframe.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And from &lt;a href=&quot;http://www.aviationpros.com/article/10389057/what-you-should-know-about-radomes&quot;&gt;this article&lt;/a&gt;:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Another important characteristic of the radome is its ability to bleed&#xA;  off static electricity. This is done through the use of&#xA;  anti-static/anti-erosion coatings and through the lightning diverter&#xA;  strips extending from the frontal area of the radome to the airframe.&#xA;  &quot;These diverter strips, says Bauer, continuously collect static&#xA;  build-up from the surface of the radome and conduct it to the airframe&#xA;  without severe sparking or arcing.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is a video that explains some of the principles of lighting diversion (note that the particular strips discussed may differ from those found on the B737). The diverter strips are discussed particularly starting &lt;a href=&quot;https://www.youtube.com/watch?v=bd23-n_Ba7o&amp;amp;feature=youtu.be&amp;amp;t=140&quot;&gt;here at 2:20&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/bd23-n_Ba7o?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-07T22:00:12.817" LastActivityDate="2016-02-07T22:00:12.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25024" PostTypeId="1" AcceptedAnswerId="25026" CreationDate="2016-02-07T22:05:13.300" Score="12" ViewCount="3640" Body="&lt;p&gt;There is a question related to this one &lt;a href=&quot;https://aviation.stackexchange.com/questions/21626/what-are-these-circles-around-the-propeller&quot;&gt;right here&lt;/a&gt; but I'm more interested in the danger of those vortices. Are they very dangerous to cause a wake turbulence for the aircraft that  comes behind this? Can it cause an accident or so?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6Dvd7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Dvd7.jpg&quot; alt=&quot;ch10&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Belgium---Air/Lockheed-C-130H-Hercules/1131694/L/&amp;amp;sid=51f39a387ccdcc6f3f7493a702db88c2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2017-08-04T12:42:24.210" Title="Can these vortices be dangerous?" Tags="&lt;turboprop&gt;&lt;vortex&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25025" PostTypeId="2" ParentId="25010" CreationDate="2016-02-07T22:26:49.460" Score="12" Body="&lt;p&gt;For a clue look at the development in the price of oil:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jE3Ov.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jE3Ov.png&quot; alt=&quot;Historical oil price chart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Historical oil price chart (&lt;a href=&quot;http://www.macrotrends.net/1369/crude-oil-price-history-chart&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the first development into the 5:1 region predates the first oil crisis (1973) and was driven by fuel economy, better range and lower airport noise, the next step was kicked off by the second crisis in the early 1980s. It took one decade to develop the engines and the airplanes which could fit them, so the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_777&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 777&lt;/a&gt; - &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE90&lt;/a&gt; combination came out in 1995 in a time of falling oil prices. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next round was only kicked off after the US invasion of Iraq which made oil prices shoot up from 2003 on. Again it took a decade for the engines to become available, but now the increase in diameter is less dramatic and existing designs can be fitted with them (&lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320neo&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_MAX&quot; rel=&quot;nofollow noreferrer&quot;&gt;737MAX&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before the early 1960s the bypass ratio could not grow more because&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;jet engines were developed for military aircraft, and more &lt;a href=&quot;https://aviation.stackexchange.com/questions/21987/why-is-the-maximum-speed-of-current-fighter-aircraft-lower-than-those-from-the-1/21988#21988&quot;&gt;emphasis was placed on top speed&lt;/a&gt; than on efficiency. Airliners used what was available (note that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_880&quot; rel=&quot;nofollow noreferrer&quot;&gt;Convair 880&lt;/a&gt; was powered by a simplified, non-afterburning version of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_J79&quot; rel=&quot;nofollow noreferrer&quot;&gt;J-79&lt;/a&gt;, which powered the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-104 Starfighter&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-4 Phantom II&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_B-58_Hustler&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-58 Hustler&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;early airliners (&lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Comet&quot; rel=&quot;nofollow noreferrer&quot;&gt;De Havilland Comet&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-104&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev 104&lt;/a&gt;) had their engines in the wing roots, so little space was available for an increased bypass ratio. When Rolls-Royce was developing the first turbofan engine, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Conway&quot; rel=&quot;nofollow noreferrer&quot;&gt;Conway&lt;/a&gt;, they limited the bypass ratio to 0.25 so it could fit into the Comet and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_Victor&quot; rel=&quot;nofollow noreferrer&quot;&gt;HP Victor&lt;/a&gt; bomber, which also had its engines in the wing roots.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The first oil crisis of 1973 kicked off the development of the unducted propfan (UDF) engine, which has been held back by noise problems. Again, it took about a decade until it could take to the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LfWFx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LfWFx.jpg&quot; alt=&quot;GE36 UDF engine fitted to the MD-81&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GE36 UDF engine fitted to the MD-81 (picture &lt;a href=&quot;http://www.b-domke.de/AviationImages/Propfan/Images/MD-81_N980DC_GE36_UDF_0809.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The development of a new engine takes longer than that of an aircraft, so every time a big push, triggered by a substantial jump in oil prices, was needed to start the development of a new generation with significantly higher bypass ratio. Once the engine technology was ready and certified, it would be quickly incorporated into many models, because the better fuel economy would force everyone to upgrade.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-14T14:58:02.717" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="25026" PostTypeId="2" ParentId="25024" CreationDate="2016-02-07T22:38:26.520" Score="20" Body="&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing does a great job in straightening the propeller swirl, but adds its own vortex. &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882?s=3%7C0.0977#8882&quot;&gt;Wake turbulence&lt;/a&gt; is dominated by the flow field around the wing.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-02-07T22:38:26.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25027" PostTypeId="1" AcceptedAnswerId="25028" CreationDate="2016-02-08T00:36:48.060" Score="5" ViewCount="4244" Body="&lt;p&gt;What is the process of 'blending' that is used as part of jet engine maintenance?&lt;/p&gt;&#xA;" OwnerUserId="9238" LastEditorUserId="12720" LastEditDate="2016-02-08T03:39:50.023" LastActivityDate="2016-02-08T03:39:50.023" Title="What is 'blending' for a turbine blade?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25028" PostTypeId="2" ParentId="25027" CreationDate="2016-02-08T00:55:54.470" Score="8" Body="&lt;p&gt;Blending is the process of filing and polishing damaged sections off of the turbine blade. This prevents further damage and extends the life of the engine without having to replace parts, making it a very economical solution. There is a limit however, as modifying the turbine blades leads to a small cost in efficiency that can build up over time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZunpH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZunpH.jpg&quot; alt=&quot;Blended vs unblended blade&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="12720" LastEditDate="2016-02-08T03:38:56.270" LastActivityDate="2016-02-08T03:38:56.270" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25029" PostTypeId="2" ParentId="24914" CreationDate="2016-02-08T01:12:30.147" Score="4" Body="&lt;p&gt;Nobody knows why except Andrei Nikolayevich Tupolev, and he is dead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Andrei Tupolev was known to insist on the fast and adequate at the expense of the theoretically correct, leading to widespread technical debt in his designs. He may have raised the nose cone for no more profound reason than to get the refueling probe in line with the pilot's vision. Once he had energetically dictated where the probe was to go, no one at the design bureau would dare suggest moving it; they would just work the forward avionics into the resulting odd shape as best they could.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev died in 1972 leaving this and many other of his decisions unexplained.&lt;/p&gt;&#xA;" OwnerUserId="453" LastActivityDate="2016-02-08T01:12:30.147" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25030" PostTypeId="1" AcceptedAnswerId="25032" CreationDate="2016-02-08T01:38:16.650" Score="2" ViewCount="776" Body="&lt;p&gt;I've noticed some sort of &quot;flight controls&quot; on an A319 vertical stabilizer. &lt;a href=&quot;https://i.stack.imgur.com/OsqBx.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OsqBx.jpg&quot; alt=&quot;a319&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the original photo&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EAxJz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EAxJz.jpg&quot; alt=&quot;a319&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are those things? Are they used for controlling the movement of the aircraft?&#xA;Source: &lt;a href=&quot;http://m.airliners.net/photo/detail/id/1524730&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt; (modified to indicate the segments of the vertical stab).&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="19" LastEditDate="2016-10-17T07:54:24.350" LastActivityDate="2016-10-17T07:54:24.350" Title="Are the panels in this vertical stabilizer part of the flight controls?" Tags="&lt;aircraft-design&gt;&lt;flight-controls&gt;&lt;vertical-stabilizer&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25031" PostTypeId="2" ParentId="25024" CreationDate="2016-02-08T01:39:34.197" Score="46" Body="&lt;p&gt;While &lt;a href=&quot;https://aviation.stackexchange.com/questions/25024/can-this-vortices-be-dangerous/25026#25026&quot;&gt;@Peter Kämpf 's answer&lt;/a&gt; is great and sufficient to answer the question, I would like to add a clarification (which should be a posted as a comment, but is too long for this format).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the image in the question, there are visible streams of condensed water vapor from the atmosphere. These streams are only present at the blade tips. The question seems to assume that these streams depict the wake from the propellers. They don't, or more accurately there are only a very small part of the wake volume.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;1. Images of tip vortices from different devices&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1a, tip vortex from a propeller&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CAuNL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CAuNL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.vansairforce.com/community/showthread.php?t=47071&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Condensed water forms because the change of pressure is &lt;em&gt;&lt;a href=&quot;http://www.ess.uci.edu/~yu/class/ess5/Chapter.6.cloud.all.pdf&quot; rel=&quot;noreferrer&quot;&gt;adiabatic&lt;/a&gt;&lt;/em&gt;, in simple terms it occurs with little exchange of heat with the neighboring regions. It occurs first where the pressure difference is large and the transition quick. (By the way, note the 8 rockets used to assist for takeoff.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1b, tip vortex from a wing&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WQ6xE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WQ6xE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.wikiwand.com/en/Wingtip_vortices&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1c: tip vortex from a rotor&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ed3FF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ed3FF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://atoptics.wordpress.com/tag/helicopter/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is not doubt the rotors spin in opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;1d, &lt;strike&gt;tip vortex from a wind turbine&lt;/strike&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MiVeJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MiVeJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://fuckyeahfluiddynamics.tumblr.com/post/91050225974/smoke-released-from-the-end-of-a-test-blade-shows&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice: Actually after looking at oddities on this image (the direction of the wind), I realized that this is an &lt;a href=&quot;http://www.aeroprobe.com/applications/examples/aeroprobe-probes-used-in-does-renewable-energy-research&quot; rel=&quot;noreferrer&quot;&gt;experimental turbine&lt;/a&gt; used by the US DoE and the &lt;a href=&quot;http://www.nrel.gov&quot; rel=&quot;noreferrer&quot;&gt;NREL&lt;/a&gt; to study winds. The white stream is actually smoke released from the blade. Probes are visible on the leading edge to measure speed at different locations of the blade. I keep the image as it's a good one.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;2. Full wake turbulence&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrary to the previous images, the ones below show the whole turbulence created by the same airfoils. While the tip vortices are materialized by condensed water vapor created by a transition from high to low pressure at the tip of the devices, the whole wake is visible only if air is not clear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;2a, turbulence from a propeller&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C1ULZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C1ULZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://www.caa.govt.nz/FIG/basic-concepts/effects-of-controls.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;Principle (no photo found, do you have one?)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;2b, turbulence from a wing&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wKcPn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wKcPn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://stayonthehill.blogspot.fr/2012/06/condensation-trails.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;2c: turbulence from a rotor&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yaNIR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yaNIR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://crashleadership.com/tag/hover/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;2d, turbulence from a wind turbine&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8O0F6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8O0F6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://www.reddit.com/r/askscience/comments/1v1mbk/why_do_modern_wind_turbines_only_have_three_long/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;3. Images where both effects are combined&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that regardless of whether they are visible or not, both the tip vortices and full wake always exist. Their visibility greatly depends, like contrails, on the air moisture and temperature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As explained by @Peter, the energy of the tip vortices is diluted in the energy of the actual wake turbulence:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h7mbc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h7mbc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://stayonthehill.blogspot.fr/2012/06/condensation-trails.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Eo6iV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Eo6iV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://wing-tips-to-leave-a-small-white-vapor-trail&quot; rel=&quot;noreferrer&quot;&gt;What causes a plane's wing tips to leave a small white vapor trail?&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4. Complexity of the wake&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wake from a wind turbine, mixing all sources of turbulence:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mvnTp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mvnTp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://fr.slideshare.net/sandiaecis/maniaci-38936527&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The tip vortex is initially a very small part of the wake, created by the high pressure air escaping from the low side of the wing. The whole wake volume grows in length and diameter as the airfoil moves. The vertex diameter grows, until there is no more energy left and air stops moving (see images in §3):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LN0Em.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LN0Em.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://petersengineering.blogspot.fr/2015/06/lifting-line-model-of-finite-span-wing.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gYEDW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gYEDW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://jazzroc.wordpress.com/tag/vortex/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this question for details: &lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence?lq=1&quot;&gt;How does an aircraft form wake turbulence?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-08-04T12:42:24.210" LastActivityDate="2017-08-04T12:42:24.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25032" PostTypeId="2" ParentId="25030" CreationDate="2016-02-08T01:49:20.537" Score="8" Body="&lt;p&gt;The part I have outlined below is the rudder. That is the only control surface on the vertical stabilizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The segments on the leading edge are just the leading edge surfaces. One may include &lt;a href=&quot;https://aviation.stackexchange.com/q/24688/1696&quot;&gt;an antenna&lt;/a&gt;, but they are only segmented for easier manufacturing and assembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ones just forward of the rudder are panels that cover the rudder attachment and actuating systems. They can be removed for inspection or maintenance purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rest of the surface, in the middle, is the main structure of the vertical stabilizer. There is a spar on the forward and aft sides, and ribs that run between them. This is all covered by one piece of skin. This creates a structure that is both strong and light weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pRdSL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pRdSL.jpg&quot; alt=&quot;Rudder shown&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is a cutaway showing the internal structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0aji6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0aji6.jpg&quot; alt=&quot;Tail structure cutaway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-02-08T01:57:50.327" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25033" PostTypeId="2" ParentId="9740" CreationDate="2016-02-08T02:15:12.533" Score="2" Body="&lt;p&gt;If you are relying on GPS to navigate that model UAV, note that some receivers have artificial limitations imposed on them due to CoCom paranoia.  The answers at the following page may be of interest:&#xA;&lt;a href=&quot;https://electronics.stackexchange.com/questions/11868/gps-units-weather-balloon&quot;&gt;https://electronics.stackexchange.com/questions/11868/gps-units-weather-balloon&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13387" LastEditorUserId="-1" LastEditDate="2017-04-13T12:33:10.950" LastActivityDate="2016-02-08T02:15:12.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25035" PostTypeId="2" ParentId="16151" CreationDate="2016-02-08T06:05:58.450" Score="5" Body="&lt;p&gt;WITH DUE RESPECT I DIFFER A BIT&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am an ICAO controller. We classify flight status as follows:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Normal= Self-explanatory.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Abnormal: Abnormal reading/performance but no danger present yet- time for anticipation  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Local Standby (urgency FAA): potential safety issue of the aircraft or of persons on board and requires timely assistance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Full emergency (distress FAA)= An emergency situation is one in which the safety of the aircraft or of persons on board or on the ground is endangered for any reason. A full emergency is imminent danger and requires immediate assistance.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;On the other hand, we should:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;GET INFO Unless clearly stated by the flight crew, take all necessary steps to ascertain aircraft identification and type, the type of emergency, the intentions of the flight crew as well as the position and level of the aircraft in order to handle the emergency intelligently &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;SEPARATE: Upon receipt of information that an aircraft is having an emergency, all possible action shall be taken immediately to safeguard all aircraft concerned. &#xA;Establish/maintain separation with other aircraft and terrain! &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ASSIST: Decide and deliver upon the most appropriate type of assistance which can be rendered&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;COORDINATE: The air traffic controller concerned shall inform and enlist the aid of any other air traffic controllers and control sectors which may be affected. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;To respond to an emergency, we  (AIR TRAFFIC CONTROLLERS - ATCOs) should demonstrate problem-detection, anticipation of threats, planning, decision-making, resilience, error management, task distribution, teamwork and performance abilities. Re-planning is part of the ATCOs duties since, as an occurrence evolves over time, new threats may appear whilst current threats may change their demands.&lt;/p&gt;&#xA;" OwnerUserId="13392" LastEditorUserId="1961" LastEditDate="2016-02-08T07:09:55.997" LastActivityDate="2016-02-08T07:09:55.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25036" PostTypeId="1" AcceptedAnswerId="25045" CreationDate="2016-02-08T06:32:20.963" Score="8" ViewCount="763" Body="&lt;p&gt;Let's say I hold PPL privileges for &lt;em&gt;Multi-Engine Land&lt;/em&gt;. Now I want to start my seaplane training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I begin my training directly on a multi-engine seaplane? Or, do I have to get a license for &lt;em&gt;Single-Engine Sea&lt;/em&gt; first before I can proceed to multi-engine?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-08-13T03:54:02.267" Title="If I have multi-engine land, can I learn multi-engine sea directly?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25037" PostTypeId="2" ParentId="24723" CreationDate="2016-02-08T08:29:13.147" Score="2" Body="&lt;p&gt;Checklists can be in any language.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For general aviation I've seen check-lists in a variety of languages. Sometimes in the local language and sometimes in English - that's in Germany, Spain and Sweden. Spain in particular seemed to have everything in Spanish. From colleagues I've heard that France is similar, most GA check-lists are in French.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For commercial aviation it varies by airline. Air France, for instance, publishes its check-lists in French (an example of these can be seen in the &lt;a href=&quot;https://www.google.co.uk/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=3&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjJgefN3-fKAhXHuRQKHQQWBpwQFggwMAI&amp;amp;url=https%3A%2F%2Fwww.bea.aero%2Fdocspa%2F2009%2Ff-cp090601.en%2Fpdf%2Ff-cp090601.en.pdf&amp;amp;usg=AFQjCNGarqs2GoVLri6qBsJlVJ05C_vwAg&amp;amp;sig2=OIzsbHGcfHxo5vSQUI8TxA&amp;amp;bvm=bv.113370389,d.ZWU&quot; rel=&quot;nofollow&quot;&gt;Air France 447 final report&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-02-08T08:29:13.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25038" PostTypeId="2" ParentId="24794" CreationDate="2016-02-08T08:40:20.813" Score="10" Body="&lt;p&gt;1) Technology is fallible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Humans are fallible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now that aircraft have GPS receivers it is rare for them to be off course by a considerable margin. That said, technology can fail and there are cases where the GPS cannot, or should not, be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew can also make mistakes, either by incorrectly reading the navigation data or by incorrectly entering flight path details into the navigation system: An aircraft may actually be 'on course' based on what the crew told it to do, but they told it the wrong thing. Depending on how data is entered into the system it's easy to add the wrong waypoint (some have very similar names, there's been a few cases of that happening) or to enter reciprocal bearings or lat/lon points.&#xA;On top of that there's simple crew distraction - if they're manually flying then they may be focussing on something else and not notice that are off-course: As happened on the Sukhoi superjet demonstration flight a few years ago.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-02-08T08:40:20.813" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25039" PostTypeId="1" AcceptedAnswerId="25126" CreationDate="2016-02-08T11:05:30.080" Score="4" ViewCount="1473" Body="&lt;p&gt;For example if whole system is build on CAN protocol that give maximum rate of 9000 messages per second with IMHO is quite low number for big plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you give me any example how this problem was solved?&#xA;Do they divide system into subsystem or use protocols like Ethernet IP?&#xA;Or maybe that number of messages is enough because they're sending only critical information?&lt;/p&gt;&#xA;" OwnerUserId="12893" LastEditorUserId="1467" LastEditDate="2016-04-08T08:00:59.937" LastActivityDate="2019-06-03T20:54:40.307" Title="How is a fly-by-wire system realized in big planes?" Tags="&lt;flight-controls&gt;&lt;avionics&gt;&lt;fly-by-wire&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25040" PostTypeId="1" AcceptedAnswerId="25042" CreationDate="2016-02-08T12:20:57.933" Score="4" ViewCount="3479" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/19454/re-engine-the-747-as-a-twinjet&quot;&gt;this terrific question&lt;/a&gt; we see the advantages of four engines over two. Namely:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine out capability: Losing an engine means losing only one quarter of the thrust, rather than half.&lt;/li&gt;&#xA;&lt;li&gt;Ground clearance.&lt;/li&gt;&#xA;&lt;li&gt;Drag: Increased yaw control with four engines in an engine-out scenario means that the vertical stabilizer can be smaller, thus reducing drag.&lt;/li&gt;&#xA;&lt;li&gt;The wing is loaded more evenly.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If that is so, then why don't new commercial airliner designs use four engines?&lt;/p&gt;&#xA;" OwnerUserId="354" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-07-05T19:37:07.120" Title="Why do modern airliners have only two engines?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="0" ClosedDate="2016-02-08T20:37:15.843" ContentLicense="CC BY-SA 3.0" />
  <row Id="25041" PostTypeId="2" ParentId="25040" CreationDate="2016-02-08T12:47:02.887" Score="16" Body="&lt;p&gt;Engines are expensive, maintenance-intensive and heavy. You only need 2 to keep a large plane in the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the days of the 747 regulations required at least 3 engines if you ventured more than 60 minutes of flying time away from a suitable diversion airport (in case the second one also failed). However as reliability of engines increased this got extended with &lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot; rel=&quot;nofollow&quot;&gt;ETOPS&lt;/a&gt; certificates.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="13197" LastEditDate="2016-04-12T14:58:33.640" LastActivityDate="2016-04-12T14:58:33.640" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25042" PostTypeId="2" ParentId="25040" CreationDate="2016-02-08T13:08:41.690" Score="9" Body="&lt;p&gt;Because there is no need for more engines. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Though one can argue that losing one engine in a twin results in loss of half the thrust, the question is how often does that happen. Engine reliability has improved significantly through the years and engine failures are quite rare today.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I'm not sure how ground clearance is an advantage for quads. For quad engined aircraft using today's high bypass turbofans, the inboard engines would have to be mounted higher for suffecient ground clearance- this is actually a disadvantage as it results in a longer landing gear.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In aircraft, more engines means more (cost and) maintenance and in a way, more things to fail, as there are more subsystems. In effect, there is no great reliability advantage of quads over twins.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One main reason for having more than two engines, ETOPS certification, is no longer relevant. In fact most of the longest routes in the world are flown by the 777, a twin.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The best way is to look at the market- there are no quad engined aircraft under development and most of the aircraft in order are twins (A380 and 747-8s are struggling to get orders). This clearly shows that the customers prefer twin engines over quads.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-08T13:08:41.690" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25043" PostTypeId="1" AcceptedAnswerId="26429" CreationDate="2016-02-08T13:51:38.973" Score="9" ViewCount="7141" Body="&lt;p&gt;What is the actual numerical reliability statistics of the modern, large-aircraft, commercial turbofan engines available today? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. How many running hours can we expect a failure after? Are there empirical or projected MTBF statistics? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is credible MTBF established for a new engine model?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a significant difference in the failure rate between engine models or manufacturers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was motivated to ask by this snippet on another answer on SE Aviation: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the days of the 747 regulations required at least 3 engines if you&#xA;  ventured more than 60 mniutes of flying time away from a suitable&#xA;  diversion airport (in case the second one also failed). &lt;strong&gt;However as&#xA;  reliability of engines increased this got extended with ETOPS&#xA;  certificates.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How rapidly has engine reliability improved? Do we have a time trend of reliability numbers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/25040/why-do-modern-airliners-have-only-two-engines&quot;&gt;Why do modern airliners have only two engines?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="22726" LastEditDate="2019-01-25T03:59:55.177" LastActivityDate="2019-01-25T03:59:55.177" Title="What are the reliability statistics for modern jet engines?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;engine-failure&gt;&lt;reliability&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25044" PostTypeId="1" CreationDate="2016-02-08T15:45:42.247" Score="7" ViewCount="2226" Body="&lt;p&gt;As you come in for landing, at what angles should the VASI or PAPI lights be visible on the approach in the Horizontal and vertical planes. {E.G. 30 degrees horizontal and 20 degrees vertical}&lt;/p&gt;&#xA;" OwnerUserId="13397" LastActivityDate="2016-02-10T23:42:25.230" Title="What is the horizontal and vertical fields of view for a VASI and a PAPI approach system as you come in to land?" Tags="&lt;papi&gt;&lt;vasi&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25045" PostTypeId="2" ParentId="25036" CreationDate="2016-02-08T17:02:51.653" Score="9" Body="&lt;p&gt;As shown on page 77 of &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/faa-s-8081-12c.pdf&quot;&gt;this &lt;/a&gt;FAA document, the various tests needed for an AMES (air multi engine sea) rating depend on the ratings you already hold and your area of operation. Depending on your area of operation, holding an AMEL (air multi engine land) rating can allow you to skip most or all of the required tasks for an AMES rating. In many cases, an AMEL rating is actually better for getting an AMES rating than a single engine sea (ASES) rating will be. So in short, you do not need an ASES rating first, but having one can make the process of getting an AMES rating easier in certain areas of operation.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="13371" LastEditDate="2016-02-08T19:47:29.167" LastActivityDate="2016-02-08T19:47:29.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25046" PostTypeId="1" AcceptedAnswerId="25049" CreationDate="2016-02-08T17:42:41.663" Score="10" ViewCount="1310" Body="&lt;p&gt;@curious-cat brought up an interesting question on &lt;a href=&quot;https://aviation.stackexchange.com/q/25027/8730&quot;&gt;another thread&lt;/a&gt;. How are the fan discs, compressor spools and turbines balanced on a jet engine. As they wear they surely get out of balance. Do they add weights as is done on your car tires? &#xA;&lt;img src=&quot;https://i.stack.imgur.com/zjZId.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what method do they use to determine where the balance point is? &#xA;I'm imagining a giant version of this&#xA;&lt;img src=&quot;https://i.stack.imgur.com/2BISx.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-04-10T07:21:47.413" Title="How are fan and compressor discs balanced?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25047" PostTypeId="1" CreationDate="2016-02-08T19:01:56.707" Score="5" ViewCount="1328" Body="&lt;p&gt;When an aircraft flies over another country are there fees associated with such flight? I am thinking particularly of international airline flights, though this might also apply to flights with the same country of origin and destination that transit another country's airspace.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Are there fees for flying through another country's airspace in general?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Are there fees for flying through the airspace associated with an airport in another country?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13400" LastEditorUserId="12720" LastEditDate="2016-02-08T19:12:25.703" LastActivityDate="2016-02-17T07:01:09.903" Title="Are there fees for international flights crossing through another country's airspace?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25048" PostTypeId="2" ParentId="21619" CreationDate="2016-02-08T19:41:23.230" Score="7" Body="&lt;p&gt;The angle of attack of the wings of a B-52 is positive. The leading edge of the wing is higher than the trailing edge. So when you see the aircraft takeoff it seems to not rotate, but when the fuselage is level, the wings are at a positive angle of attack. When the B-52 is in level flight, the nose is down, you can not see the nose from the cockpit and it is like you are sitting on a cloud. &lt;/p&gt;&#xA;" OwnerUserId="13401" LastEditorUserId="1961" LastEditDate="2016-02-08T20:22:28.927" LastActivityDate="2016-02-08T20:22:28.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25049" PostTypeId="2" ParentId="25046" CreationDate="2016-02-08T19:43:26.733" Score="5" Body="&lt;p&gt;This article &lt;a href=&quot;https://web.archive.org/web/20180213081257/http://articles.sae.org/12407/&quot; rel=&quot;nofollow noreferrer&quot;&gt;covers the issue&lt;/a&gt; (and is a pretty interesting read) but does not really explain how they do it. It just says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After machine balancing, the part can then be manipulated (mass added&#xA;  or removed) and retested on the machine until satisfactory balance&#xA;  tolerance is achieved.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In answer to this question,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And what method do they use to determine where the balance point is?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The device is pretty similar to that of a tire balance, &lt;a href=&quot;https://www.youtube.com/watch?v=vpGMF8PYw0Y&quot; rel=&quot;nofollow noreferrer&quot;&gt;here is a video of one in use&lt;/a&gt; and here is an &lt;a href=&quot;https://www.mtiinstruments.com/wp-content/uploads/2018/09/7001-0130-PBS-4100-Plus-Brochure.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;interesting sales brochure for one&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1467" LastEditDate="2019-04-10T07:21:47.413" LastActivityDate="2019-04-10T07:21:47.413" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="25050" PostTypeId="1" AcceptedAnswerId="25051" CreationDate="2016-02-08T19:54:24.200" Score="38" ViewCount="6610" Body="&lt;p&gt;This symbol is on the tarmac at Ramona, CA airport.  I've seen it at other small GA airports from Google Earth but I don't know what it is.  Can someone please explain?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EEcxn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EEcxn.jpg&quot; alt=&quot;Ramona, CA airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9161" LastEditorUserId="1467" LastEditDate="2016-02-09T08:34:04.743" LastActivityDate="2016-02-09T08:34:04.743" Title="What is this star shaped symbol on the tarmac?" Tags="&lt;airport-markings&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25051" PostTypeId="2" ParentId="25050" CreationDate="2016-02-08T20:05:38.580" Score="38" Body="&lt;p&gt;That is a Compass Rose, painted on a Compass Calibration Pad. It's used to mark a location on the airport surface that is suitable for calibrating the compass of an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's one in a slightly different style:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zfzae.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zfzae.jpg&quot; alt=&quot;Compass pad photo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and a more basic one from an FAA diagram:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eDzVG.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eDzVG.png&quot; alt=&quot;Compass pad diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More information on the requirements for the compass rose / compass pad can be found in &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentnumber/150_5300-13&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5300-13&lt;/a&gt;, in Appendix 6.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-02-08T20:05:38.580" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25052" PostTypeId="1" AcceptedAnswerId="25053" CreationDate="2016-02-08T20:19:12.403" Score="5" ViewCount="544" Body="&lt;p&gt;I can understand that altitudes may be &quot;by ATC&quot;, but why can a route also be marked with &quot;by ATC&quot;? All SID routes need prior clearance by ATC, right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, in SID RWY 16 for ZGSZ/SZX, MEPOG-7X and LKC-7X are &quot;by ATC&quot;, while others are not. I know that LKC-7X is not a regular route flown, but still: what does &quot;by ATC&quot; mean here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U7sHp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U7sHp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(Source: ZGSZ AD 2.24-7F, AIP China)&lt;/p&gt;&#xA;" OwnerDisplayName="user13377" LastActivityDate="2016-02-08T20:37:03.190" Title="What Does &quot;By ATC&quot; Mean for an SID Route?" Tags="&lt;air-traffic-control&gt;&lt;sid-star&gt;&lt;departure-sid&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25053" PostTypeId="2" ParentId="25052" CreationDate="2016-02-08T20:37:03.190" Score="6" Body="&lt;p&gt;It means, don't file that transition yourself.  ATC may assign it, but it's their option to assign it or leave you on what you filed.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-02-08T20:37:03.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25054" PostTypeId="1" AcceptedAnswerId="25070" CreationDate="2016-02-08T20:48:57.317" Score="5" ViewCount="1421" Body="&lt;p&gt;The wings of subsonic planes have usually a very low surface area and aspect ratio as big as possible. However, in supersonic aircraft, wings with more wetted area (e.g delta wings) are used. Is this because skin friction decreases with speed or because in supersonic flight this type of drag is no longer the main concern?&lt;/p&gt;&#xA;" OwnerUserId="13402" LastActivityDate="2017-04-30T13:37:13.217" Title="Does skin friction drag decrease with velocity?" Tags="&lt;supersonic&gt;&lt;drag&gt;&lt;delta-wing&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25055" PostTypeId="2" ParentId="25047" CreationDate="2016-02-08T21:07:00.157" Score="6" Body="&lt;p&gt;Most countries have implemented route charges billed to aircrafts overflying their territory and by doing so using their control infrastructure. Those fees are usually computed according the distance flown and aircraft weight, small aircrafts (eg. less than 2,000 kg in Europe) may be exempt. They are collected for every flight over the territory, both domestic and international.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the same way, some countries charge terminal fees when the airport control infrastructure is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those fees are most usually levied for flight performed according IFR (Instrument Flight Rules), not VFR (Visual Flight Rules).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Europe, the EUROCONTROL organization is empowered by States to collect route charges and terminal fees.&lt;/p&gt;&#xA;" OwnerUserId="12957" LastActivityDate="2016-02-08T21:07:00.157" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25056" PostTypeId="1" CreationDate="2016-02-08T21:08:31.273" Score="4" ViewCount="384" Body="&lt;p&gt;Found this during a garden clearance. Have included a photo of serial number. Could you identify where this came from?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ruFda.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ruFda.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/SHyDv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SHyDv.jpg&quot; alt=&quot;serial number&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;dimensions: width 115cm length 140cm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dp5I1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dp5I1.jpg&quot; alt=&quot;side view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LSCfc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LSCfc.jpg&quot; alt=&quot;close up&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13404" LastEditorUserId="8000" LastEditDate="2016-02-21T13:30:58.440" LastActivityDate="2016-02-21T13:30:58.440" Title="What is this Perspex bubble?" Tags="&lt;military&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25057" PostTypeId="1" CreationDate="2016-02-08T21:18:05.043" Score="5" ViewCount="2926" Body="&lt;p&gt;In July 2008 a Qantas 747 suffered decompression at 29,000 ft and the pilots then descended to 10,000 ft in the space of six minutes . More details here : &lt;a href=&quot;https://en.wikipedia.org/wiki/Qantas_Flight_30&quot; rel=&quot;nofollow&quot;&gt;wikipedia.org/.../Qantas_Flight, 30&lt;/a&gt; .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm curious to know if you're in a large aircraft descending at that rate would there be a strong sensation of descent for the passengers? Would the plane be angled downwards in a way that wouldn't normally happen or some other sensation not normally experienced when travelling on large civil aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I appreciate that in this case the masks were down and there might have been noise/wind associated with the actual incident, so clearly it did feel strange to these passengers, but if the descent was done as a test at that rate would it feel strange?&lt;/p&gt;&#xA;" OwnerUserId="4007" LastEditorUserId="19" LastEditDate="2017-02-23T10:51:51.967" LastActivityDate="2017-02-23T10:51:51.967" Title="Would a 19,000 ft descent in 6 minutes feel noticably different to passengers?" Tags="&lt;airliner&gt;&lt;emergency&gt;&lt;boeing-747&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25058" PostTypeId="1" AcceptedAnswerId="25062" CreationDate="2016-02-08T21:32:20.333" Score="10" ViewCount="9767" Body="&lt;p&gt;A follow-up from &lt;a href=&quot;https://aviation.stackexchange.com/questions/25050/can-someone-tell-me-what-this-star-shaped-symbol-on-the-tarmac-is&quot;&gt;this&lt;/a&gt; question; one of the answers mentioned that the compass rose in the picture was used to calibrate an aircraft's compass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But &lt;em&gt;how&lt;/em&gt; does that actually work? Do you park the aircraft on top or something?&lt;/p&gt;&#xA;" OwnerUserId="2265" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2019-01-22T21:43:52.093" Title="How do you calibrate the compass of an aircraft on a compass rose?" Tags="&lt;airport-markings&gt;&lt;magnetic-compass&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25059" PostTypeId="1" AcceptedAnswerId="25078" CreationDate="2016-02-08T21:40:14.660" Score="7" ViewCount="3136" Body="&lt;p&gt;I was watching some aircraft today and noticed a red marking on two of them.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/vFsz1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vFsz1.jpg&quot; alt=&quot;aa737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7iuVw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7iuVw.jpg&quot; alt=&quot;aa737ng&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that? I've seen that marking on many other aircraft.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="167" LastEditDate="2016-02-10T01:52:23.297" LastActivityDate="2016-02-10T01:52:23.297" Title="What's the purpose of this red marking on the fuselage of a Boeing 737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;aircraft-marking&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25060" PostTypeId="2" ParentId="25059" CreationDate="2016-02-08T21:47:29.593" Score="3" Body="&lt;p&gt;They are the markings for danger zone around the engines telling people to stay out of that area. If you notice, the engines also have that marking as well. They correspond to the side of the aircraft in the danger zone image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6bcFz.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6bcFz.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_3_08/article_04_3.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;boeing.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="1467" LastEditDate="2016-02-09T13:57:44.643" LastActivityDate="2016-02-09T13:57:44.643" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25061" PostTypeId="2" ParentId="25056" CreationDate="2016-02-08T22:01:47.763" Score="2" Body="&lt;p&gt;Few thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Label font does look British/Commonwealth in some way.&lt;/li&gt;&#xA;&lt;li&gt;Flat bottom- unlikely to be cockpit canopy that curve down on the sides.&lt;/li&gt;&#xA;&lt;li&gt;Not compatible with weapons- Search and Rescue aircraft?&lt;/li&gt;&#xA;&lt;li&gt;Large curvature: Slow aircraft?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;At some point I was considering the rear window of the Consolidated Catalina but it doesn't quite seem to fit the bill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o1M2J.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o1M2J.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Tony Hisgett on Wikicommons/&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Consolidated_PBY_Catalina_2_%287509915628%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2016-02-08T22:01:47.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25062" PostTypeId="2" ParentId="25058" CreationDate="2016-02-08T22:35:43.180" Score="16" Body="&lt;p&gt;Most aircraft compasses include compensating magnets to correct for installation error (due to natural magnetic fields in an aircraft from steel parts and electrical equipment). When installing a new compass or performing significant electrical work on an aircraft the compass may need to be re-calibrated and the compensating magnets adjusted (typically by turning small screws, like the ones shown below).&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ArcDh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ArcDhm.jpg&quot; alt=&quot;Compass compensating screws&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several ways to calibrate (or &quot;swing&quot;) an aircraft compass - the use of a properly-surveyed compass rose constructed to applicable FAA standards and marked on an airport is one of them, and ensures the compass swing is being performed in an area free of magnetic disturbances which should result in an accurate calibration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic procedure is to taxi the aircraft to the compass rose and align it with the compass directions using a combination of the ground markings and a &quot;gunsight&quot; compass. A full description of the procedure can be found in &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861&quot; rel=&quot;noreferrer&quot;&gt;AC 43-13.1&lt;/a&gt;, Chapter 12-37 (&quot;Compass Swing&quot;), but the quick-and-dirty version is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Taxi out to the compass rose and align the aircraft so it is pointing toward Magnetic North.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adjust the compass compensating magnets so that the compass reads North.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Turn the airplane so it is pointing toward Magnetic East (090).&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adjust the compass compensating magnets so that the compass reads East.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Turn the airplane so it is pointing toward Magnetic South (180).&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adjust the compass compensating magnets to remove &lt;em&gt;one half&lt;/em&gt; of the &quot;South&quot; error.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Turn the airplane so it is pointing toward Magnetic West (270)&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adjust the compass compensating magnets to remove &lt;em&gt;one half&lt;/em&gt; of the &quot;West&quot; error.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Once the compensating magnets have been adjusted a Compass Deviation Card is prepared to inform the pilot of the remaining compass error.&lt;br&gt;&#xA;Beginning with Magnetic West (270) turn the aircraft to align with each of the 30-degree lines on the compass rose (270, 300, 330, North, 30, 60, 90, 120, 150, 180, 210, 240), and the error is recorded on a compass deviation card similar to the one shown below.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/G2Dfd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G2Dfd.jpg&quot; alt=&quot;Compass Deviation Card&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;A compass reading within ±10 degrees on each 30-degree heading marker is considered acceptable per AC 43-13, and better results are usually achieved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The compass swing is typically performed with the engine and electrical accessories (radios) running per AC 43-13. Some mechanics may also perform a second swing with radios off, and include an alternate deviation card for that configuration.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-02-08T22:43:05.013" LastActivityDate="2016-02-08T22:43:05.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25064" PostTypeId="2" ParentId="25057" CreationDate="2016-02-08T23:57:52.763" Score="-1" Body="&lt;p&gt;Yes, it would feel like an elevator descending very quickly. Elevators in small buildings generally descend at around 500ft/min. As an aviator you're taught that this is a comfortable descent rate for almost everyone, and it's what most General Aviation (GA) pilots shoot for. Elevators in most skyscrapers operate up to 2000ft/min. At 2000ft/min a human body reaches roughly one-fifth of its free fall velocity, making a person feel 20% lighter. This is a noticeable and sometimes nauseating effect. The other way that people feel descent rates is through pressure changes, often making ears pop and hurting young children. This isn't as much of a factor for commercial flights as their pressure changes only slightly above 10,000ft MSL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mentioned that most GA aircraft ascend/descend around 500/ft min for comfort. Most turbine or commercial aircraft will ascend/descend on instrument clearances that call for rates of 1000ft/min - 1500ft/min.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots in the Qantas case did a great job. They achieved the perfect glide slope for that aircraft and conditions. Gliding that plane for 20 minutes would have resulted in a splashdown for most pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anectdotally, I am a pilot and have descended at 3000+ ft/min and can tell you it is VERY disconcerting if you're not conditioned for it. &lt;/p&gt;&#xA;" OwnerUserId="13408" LastActivityDate="2016-02-08T23:57:52.763" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25065" PostTypeId="2" ParentId="16410" CreationDate="2016-02-09T00:09:38.407" Score="5" Body="&lt;p&gt;It's a no - simply because of the AoA limiter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the MPO switch is only for getting out of a Deep Stall condition (the switch was added around Block 5).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the F-16MATV program they removed the AoA limiter and tested it (including A-A) in the early 90s. It could do all the high Alpha stuff the YF-22 could do simple as really. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes it was Multi Axis Thrust Vectoring (MATV) not 2D - it had to be - the TV is basically providing the Yaw directional stability the tail cannot provide at high Alpha (not unique affects most single tail jets).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TV was going to be fitted to the entire fleet - the MATV had a GE engine but P&amp;amp;W had also started on one - but they decided it wasn't required.&lt;/p&gt;&#xA;" OwnerUserId="13409" LastActivityDate="2016-02-09T00:09:38.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25066" PostTypeId="2" ParentId="25057" CreationDate="2016-02-09T01:02:04.567" Score="16" Body="&lt;p&gt;From the physical side, you can not measure / feel if you are at a constant altitude or if you are ascending / descending with &lt;em&gt;constant speed&lt;/em&gt;. What you can feel is the change of speed in any direction, and acceleration acting in an unexpected direction. This causes the usual sensations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Accelerating / braking on the runway: You are pressed into the seat / belt.&lt;/li&gt;&#xA;&lt;li&gt;Weird feeling right when the aircraft becomes airborne: The aircraft accelerates upwards, which presses you into the seat with more than 1g. This higher g-force feels strange.&lt;/li&gt;&#xA;&lt;li&gt;While climbing, the aircraft still accelerates, but the more strange feeling comes from the fact that the force doesn't point down to the floor of the aircraft, but more backwards. Your eyes see that you are sitting upright in the aircraft, but it feels more like lying.&lt;/li&gt;&#xA;&lt;li&gt;At some point, usually when the flaps are retracted, the climb rate decreases suddenly and it feels as if the aircraft falls. This is because the aircraft accelerated downwards - tough it still climbs, but at lower rate.&lt;/li&gt;&#xA;&lt;li&gt;Usually, you don't feel much during a coordinated turn. Maybe you feel a little heavier, but when you look out of the window and don't see horizon, this again gives a strange feeling.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course, the passengers of that flight did have several sensations. right after the incident, the aircraft for sure has done some unusual movements, plus what the pilots did. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.atsb.gov.au/publications/investigation_reports/2008/AAIR/pdf/AO2008053_Prelim.pdf&quot; rel=&quot;noreferrer&quot;&gt;reference #7&lt;/a&gt; of the Wikipedia article contains this diagram on page 36:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Fa0u1.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fa0u1.png&quot; alt=&quot;Chart of flight data&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Directly after the incident, the aircraft climbed a little and the speed brakes were deployed (50%) to reduce speed. This was for sure noticeable by the passengers. And I guess the aircraft started to descend faster than usual, so the sensation of &quot;becoming lighter&quot; will have been much stronger/longer than usual.&#xA;After this, the aircraft descended with a quite constant rate for several minutes. This doesn't cause the feeling of being lighter. Maybe the attitude was unusual which means gravity doesn't push you vertically into the seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, when the aircraft reached 10,000ft, it accelerated upwards to stop the descent. At this moment, the passengers felt heavier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(If you have a closer look, the descending part isn't a perfect straight line. This wasn't a smooth ride, but as said, a constant descent rate doesn't cause a sensation)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this is just about the sensation of acceleration so far. The passengers for sure have noticed the drop in cabin pressure, drop in temperature, more noise and so on.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="1696" LastEditDate="2016-02-09T15:25:38.103" LastActivityDate="2016-02-09T15:25:38.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25067" PostTypeId="1" AcceptedAnswerId="25075" CreationDate="2016-02-09T03:49:29.097" Score="5" ViewCount="2295" Body="&lt;p&gt;Race cars can be refueled while the engine is running. I assume this is a dangerous task done by highly specialised technicians.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ground support is &lt;a href=&quot;https://aviation.stackexchange.com/questions/2605/can-large-airliners-be-operated-without-ground-support&quot;&gt;not available&lt;/a&gt;, an airliner may keep the APU running to be able to provide power to restart the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ground support is not available and refuel is needed, can an airliner refuel while the APU is running (technically and legally)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the question is too broad, it can be narrowed to best sellers (B737 and A320 families).&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-09T13:01:02.030" Title="Can an airliner be refueled while the APU is running?" Tags="&lt;ground-operations&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25070" PostTypeId="2" ParentId="25054" CreationDate="2016-02-09T07:51:25.647" Score="6" Body="&lt;p&gt;Your question is about friction drag while the text is mainly about aspect ratio. You seem to explain the choice of aspect ratio to be based on friction drag. This is not correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/716/what-dictates-the-aspect-ratio-of-an-aircrafts-wing&quot;&gt;Here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5047/how-does-chord-length-affect-wing-design&quot;&gt;here&lt;/a&gt; are some good answers to explain the choice of aspect ratio. You will see that it has mostly to do with structural strength and wing volume to pack enough fuel. For supersonic aircraft the &lt;a href=&quot;https://aviation.stackexchange.com/questions/22198/what-are-the-advantages-and-disadvantages-of-a-delta-wing-compared-to-a-swept-wi/22209?s=3%7C0.2752#22209&quot;&gt;delta wing&lt;/a&gt; provides a highly swept leading edge, a stiff, light wing and good low-speed characteristics even with the thin airfoils which are helpful in supersonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, aspect ratio becomes less important the faster the aircraft flies, because it has more air flowing past per unit of time  for creating lift. At supersonic speed some of the drag is proportional to the local inclination of the surface, so the designers try to make the aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule&quot;&gt;as sleek as possible&lt;/a&gt;. To put it bluntly, a subsonic aircraft likes to be as wide as possible to reduce &lt;a href=&quot;https://aviation.stackexchange.com/questions/24494/induced-drag-of-the-elliptical-wing/24506#24506&quot;&gt;induced drag&lt;/a&gt;, while a supersonic aircraft likes being longer to reduce &lt;a href=&quot;https://aviation.stackexchange.com/questions/24414/why-when-is-the-blunt-nose-better/24424?s=1%7C0.2685#24424&quot;&gt;wave drag&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Friction drag will go up with the square of velocity if all other parameters are constant. Since a higher velocity increases the Reynolds number (the ratio of inertial to viscous forces), in the real world the increase is slightly less than with the square of velocity. Since lift also goes up with velocity squared, the airplane can &lt;a href=&quot;https://aviation.stackexchange.com/questions/17647/why-do-supersonic-planes-fly-higher-than-subsonic-airliners/17667#17667&quot;&gt;fly at higher altitude&lt;/a&gt; where the density is lower, which reduces both lift and drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you need to consider the change in temperature over altitude: Air gets cooler when it expands, and cooler air causes higher viscous forces. By flying higher, the Reynolds number goes down again and the viscous drag goes up. In total, flying faster and higher will result in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/24641/drag-as-a-function-of-altitude/24644#24644&quot;&gt;slight increase of the absolute friction drag&lt;/a&gt; at the same lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you &lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956?s=1%7C0.1277#16956&quot;&gt;plot the drag coefficient over flow path length&lt;/a&gt; you will find that lengthening the flow path will generally increase drag less than proportionally. Only when the boundary layer is laminar and lengthening the flow path adds a turbulent transition will you find that &lt;a href=&quot;https://aviation.stackexchange.com/questions/36678/how-does-reynolds-number-affect-skin-friction-drag/36683#36683&quot;&gt;friction drag briefly goes up&lt;/a&gt; more than proportionally. &lt;a href=&quot;https://aviation.stackexchange.com/questions/24752/is-a-golf-ball-surface-a-good-idea-for-wings-or-fuselage/24759#24759&quot;&gt;Sometimes it is helpful to force that transition&lt;/a&gt;, but mostly it comes sooner than the engineers like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please follow the links and read the linked answers, only then is this answer complete.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-04-30T13:37:13.217" LastActivityDate="2017-04-30T13:37:13.217" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25072" PostTypeId="1" AcceptedAnswerId="25073" CreationDate="2016-02-09T08:44:15.057" Score="17" ViewCount="3623" Body="&lt;p&gt;What is the reason for painting &lt;a href=&quot;https://www.thebalancecareers.com/what-is-etops-282945&quot; rel=&quot;nofollow noreferrer&quot;&gt;ETOPS&lt;/a&gt; on the door of the nose gear?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/leI9c.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/leI9c.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&quot;ETOPS&quot; marking on a B737-800 (&lt;a href=&quot;http://www.nycaviation.com/2012/04/photos-why-southwests-first-boeing-737-800-is-kind-of-a-big-deal/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Markings on the belly are supposed to be useful for ground handlers, what is it supposed to do here?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-21T10:12:15.853" LastActivityDate="2019-11-21T10:12:15.853" Title="Why is there an ETOPS marking on the nosewheel door?" Tags="&lt;etops&gt;&lt;aircraft-marking&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="25073" PostTypeId="2" ParentId="25072" CreationDate="2016-02-09T10:21:41.847" Score="26" Body="&lt;p&gt;You're correct that it is for ground handlers; more importantly, it is for mechanics. It is important to identify the aircraft as ETOPS as the servicing and checking requirements are different for ETOPS and non-ETOPS aircraft. For ETOPS aircraft, two critical systems (like engines) should have differnt maintenance personnel to avoid them making the same mistakes in both of them.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/121.374&quot; rel=&quot;noreferrer&quot;&gt;14 CFR § 121.374 Continuous airworthiness maintenance program (CAMP) for two-engine ETOPS&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(c) &lt;strong&gt;Limitations on dual maintenance&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;(1) Except as specified in paragraph (c)(2), the certificate holder may not perform scheduled or unscheduled dual maintenance during the same maintenance visit on the same or a substantially similar ETOPS Significant System listed in the ETOPS maintenance document, if the improper maintenance could result in the failure of an ETOPS Significant System.&lt;/p&gt;&#xA;&lt;p&gt;(2) In the event dual maintenance as defined in paragraph (c)(1) of this section cannot be avoided, the certificate holder may perform maintenance provided:&lt;/p&gt;&#xA;&lt;p&gt;(i) The maintenance action on each affected ETOPS Significant System is performed by a different technician, or&lt;/p&gt;&#xA;&lt;p&gt;(ii) The maintenance action on each affected ETOPS Significant System is performed by the same technician under the direct supervision of a second qualified individual; and&lt;/p&gt;&#xA;&lt;p&gt;(iii) For either paragraph (c)(2)(i) or (ii) of this section, a qualified individual conducts a ground verification test and any in-flight verification test required under the program developed pursuant to paragraph (d) of this section.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In the same vein, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/m02txt.html&quot; rel=&quot;noreferrer&quot;&gt;from Boeing&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Strategies for Avoiding Multi-Engine Maintenance Errors&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;After investigating several multi-engine maintenance events, Boeing identified a key strategy for avoiding multi-engine maintenance error: If possible, operators and repair stations should avoid performing maintenance on multiple engines using the same personnel during a single maintenance visit. Following this strategy should also minimize the potential that improper maintenance will occur on redundant or backup critical systems, such as flight controls, electrical generation and distribution, and hydraulics.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;If the NLG doors have ETOPS written on them it would be easier for the technicians to identfy the aircraft and perform checks/maintenance as required, using two different operators, if required.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-09T10:21:41.847" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25075" PostTypeId="2" ParentId="25067" CreationDate="2016-02-09T13:01:02.030" Score="8" Body="&lt;p&gt;Refueling an airliner with APU running is a perfectly normal procedure and it is done daily all around the world. The APU is located at the tail cone partially to reduce the risk of fire spreading to the fuel tanks, which are normally in the wings and center fuselage.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some operators and authorities (not all) restrict starting and/or stopping the APU while fueling.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-02-09T13:01:02.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25078" PostTypeId="2" ParentId="25059" CreationDate="2016-02-09T13:50:43.200" Score="9" Body="&lt;p&gt;@SMSvonderTann is correct. The marking is there for warning ground personnel about engine hazrd. In this photo (of a 737) you can see 'INGESTION HAZARD' written above the line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QtwLm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QtwLm.jpg&quot; alt=&quot;737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airliners.net&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;http://www.canstockphoto.com/737-ingestion-haz-0016343.html&quot; rel=&quot;noreferrer&quot;&gt;this image&lt;/a&gt; it is possible to zoom in to see it much more clearly. Note that this marking is not found in all 737s. The danger area is marked with two lines- one in forward fuselage and another in the engine, as can be seen in @mins photo, which I've put below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mpEr8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mpEr8.jpg&quot; alt=&quot;B737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from airlinereporter.com&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, as @mins notes, the lines in 747 are for equipment positioning (to prevent damage to fairing, looks like)&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-09T13:50:43.200" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25079" PostTypeId="1" CreationDate="2016-02-09T15:25:41.277" Score="0" ViewCount="54880" Body="&lt;p&gt;This &lt;a href=&quot;http://gizmodo.com/5857866/watch-this-230-ton-airbus-a330-stopping-in-midair-for-a-few-seconds&quot; rel=&quot;nofollow&quot;&gt;Gizmodo link&lt;/a&gt; shows that a commercial passenger aircraft can stay at single location without any movement with respect to ground. (Is it real, an illusion, or faked?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have heard a friend saying that this happens for flights into Heathrow airport when the runway is busy with many aircraft required to land. I have argued with him about the holding circuit which basically requires airliner to follow a path around a airport, he is for sure that he has experienced such a thing happening when he was on board and also saw it live many times.&lt;/p&gt;&#xA;" OwnerUserId="13422" LastEditorUserId="5517" LastEditDate="2016-02-09T17:09:43.650" LastActivityDate="2016-02-09T17:09:43.650" Title="Can a passenger plane stand still in the air, or hover at a fixed location above a ground?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;airport&gt;&lt;passenger&gt;&lt;stall&gt;" AnswerCount="3" CommentCount="10" ClosedDate="2016-02-09T17:29:31.460" ContentLicense="CC BY-SA 3.0" />
  <row Id="25080" PostTypeId="2" ParentId="25079" CreationDate="2016-02-09T15:46:41.307" Score="7" Body="&lt;p&gt;&lt;strong&gt;NO&lt;/strong&gt;, at least not during landing. And especially not an Airbus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;While up in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_stream&quot;&gt;jet stream&lt;/a&gt; a 150 knot wind is normal, wind over 100 knots (185 km/h, 115 mph) near the ground only occurs in hurricanes (and tornadoes) and would be so turbulent that landing it it would be most likely out of question.&lt;/li&gt;&#xA;&lt;li&gt;When landing in strong head wind the pilots will use higher air speed. This is because strong winds have a nasty habit of changing in strength or direction quickly and if the head wind reduced suddenly, the plane would loose lift and crash. So the pilots maintain some minimum ground speed to have a safety margin for that case.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Airbus even has a minimum ground speed warning exactly to keep the pilots out of this risky flight regime and that would be blaring in cockpit if the A330 in the video really almost stopped in midair. There must be something wrong with it (the linked article does not link to a video, only a screencap and one can't tell from screencap what is going on).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-02-09T15:52:24.470" LastActivityDate="2016-02-09T15:52:24.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25081" PostTypeId="2" ParentId="25079" CreationDate="2016-02-09T15:46:54.980" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;can a commercial passenger aircraft stay at single location without any movement with respect to ground?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In theory it could, with strong enough headwinds, low weight (no passengers nor cargo or baggages), deployed high-lift devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the video it does not happen and I seriously doubt it has ever happened in real life.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;i have heard a friend saying that this happens for flights in Heathrow airport when the runway is busy with many aircraft's required to land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is simply false&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;i have argued with him about the holding circuit which basically requires airliner to follow a path around a airport&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That is correct&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;he is for sure that he has experienced such a thing hapening when he was on board and also saw it live many times.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Either he as flown in an An-2 (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/15853/what-is-the-fastest-recorded-backward-flying-plane&quot;&gt;linked&lt;/a&gt; question) or he simply dreamt about it.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-09T15:46:54.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25082" PostTypeId="2" ParentId="25079" CreationDate="2016-02-09T15:47:35.087" Score="3" Body="&lt;p&gt;An airplane cannot stand still in the air as it requires air flow over the wings to create lift. An airplane can be stationary over the ground if the air is moving over the ground quickly enough. A lightly weighted aircraft can fly slower than a heavy one, but even flying just above stall speed you would need a headwind well over 100mph in order for a jet to be stationary with respect to the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this video the airplane &lt;em&gt;appears&lt;/em&gt; to be flying must slower than it actually is due to the angles viewed and other factors. It was never stationary with respect to the ground. Commercial jets don't &quot;hover&quot;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does happen when there's traffic is that they are put into a holding pattern. This is generally away from the airport, not around the airport. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-09T15:47:35.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25083" PostTypeId="1" AcceptedAnswerId="25085" CreationDate="2016-02-09T16:41:55.553" Score="6" ViewCount="632" Body="&lt;p&gt;I've been looking online for the different ratings and classes of helicopters but I can't find much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example in fixed wing aircraft you have retractable gear, constant speed propeller, IFR, multi-engine, tricycle gear, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am curious to know what the helicopter equivalents are. What does a basic helicopter rating allow you to fly? What comes after that?&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="167" LastEditDate="2016-02-10T02:05:19.417" LastActivityDate="2016-02-10T17:08:58.370" Title="Do some helicopters require classes, type ratings, or special endorsements, the way some airplanes do?" Tags="&lt;helicopter&gt;&lt;pilot-certification&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25084" PostTypeId="1" AcceptedAnswerId="25088" CreationDate="2016-02-09T16:48:37.120" Score="11" ViewCount="7308" Body="&lt;p&gt;On aircraft carriers there is a catapult that slingshots aircraft so that they can gain lift on the short carrier deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have a few related questions - the first is what is the force exerted / required by the catapult to sufficiently accelerate the aircraft; and is it adjusted per aircraft type or a uniform value?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine carrier takeoffs/landing cause additional stress on the aircraft; but does it have a dramatic effect on the lifetime of the aircraft vs. their non-carrier configured twins? Or is it compensated for by a more frequent maintenance schedule?&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-12-08T16:55:37.570" Title="What is the force exerted by the catapult on aircraft carriers?" Tags="&lt;military&gt;&lt;aircraft-performance&gt;&lt;aircraft-carrier&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25085" PostTypeId="2" ParentId="25083" CreationDate="2016-02-09T17:02:27.677" Score="4" Body="&lt;p&gt;I can't see a connection between &quot;classes&quot; of helicopters and ratings.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also don't specify which jurisdiction so I will answer for the UK CAA which I know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To fly any helicopter under VFR needs nothing more than your license, gained on any type, and a type rating for the specific aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I gained my license on the R22.  I am therefore also type rated on it.  The second aircraft I learned to fly was the B206 which is jet powered.  I didn't need anything extra than the appropriate type rating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can fly any helicopter for which I am rated under VFR.  If I had an IFR certification, I could fly any helicopter I am rated for under VFR, and any IFR certified helicopter for which I am rated under IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Difference training&quot; is simply part of the the type rating.  For example, if I ever learned to fly a craft with a retractable undercarriage, I would be rated to fly that type, but not another type with retractable gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does differ is the type of license, e.g. CPL or ATP.  I would need that license in order to carry passengers for hire and to conduct other commercial operations, but I still need a type rating on whatever helicopter I use to carry those passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Put it this way, the day after I gained my license, I could climb into any helicopter and act as pilot under training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope that's all clear!&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2016-02-09T17:02:27.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25086" PostTypeId="2" ParentId="25084" CreationDate="2016-02-09T17:23:19.167" Score="4" Body="&lt;p&gt;Catapults powered by steam from the carrier's engines, the amount of pressure is set per aircraft according to its weight and how fast it needs to be at the end of the deck. If too little steam power is set the airplane will not get up to speed and will end up in the ocean, too much and the airplane can be damaged by the excess force. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carrier aircraft have to be much tougher than their non-carrier cousins, and have to be specially designed for those kinds of operations. The whole structure has to be strong enough for repeated carrier landings and takeoffs, and also it has to be able to fit on the elevator, so have folding wings of some sort. They are generally so well built that they last as long as their non-carrier counterparts. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-09T17:23:19.167" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25087" PostTypeId="2" ParentId="24435" CreationDate="2016-02-09T22:50:05.790" Score="8" Body="&lt;p&gt;The nacelle is not some solid block. For the flow it looks like a hollow, slightly blocked tube.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flow ahead of the nacelle is indeed slowed down in flight, but only a little, entering the intake face at a flow speed of around Mach 0.4 to 0.5. This compresses the air ahead of the nacelle when flying in cruise at around Mach 0.8, so what enters the intake is already slightly compressed. Note that this compression does not involve boundary layers or shocks, so it is very efficient. The effect of the compression is that some of the air flowing towards the nacelle is pressed aside to flow around it. To avoid flow separation, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11723/why-do-engine-cowl-lips-appear-larger-and-more-blunt-on-the-sides-than-on-the-to/11730?s=1%7C0.1656#11730&quot;&gt;intake lip is rounded&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pre-compression helps, because it raises the pressure in the whole engine and increases its thrust. What might be looked at as drag is in fact increasing the thrust of the engine! Of course, by further compressing and heating the ingested air the engine accelerates it, so the outflow speed of the core flow is easily double its entry speed. The outflow fills up the cross section of the engine, so the outer flow never has to flow into a void and experience separation (which is responsible for most of the drag of blunt bodies). Instead, it meets a faster jet of air once it has passed the engine fairing and is accelerated during the mixing process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only if the engine is idling or off will the &lt;a href=&quot;https://aviation.stackexchange.com/questions/23327/about-how-much-drag-does-a-non-operating-engine-create/23331?s=9%7C0.0736#23331&quot;&gt;nacelle cause real drag&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-02-10T07:09:24.217" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25088" PostTypeId="2" ParentId="25084" CreationDate="2016-02-10T00:04:31.713" Score="11" Body="&lt;p&gt;The force applied by the steam catapult is adjusted according to the aircraft T/O weight (by extension, the type). The catapult has to accelerate the aicraft to some airspeed at the end of the launch procedure. This required force depends on the aircraft mass. From USN &lt;a href=&quot;https://www.cnatra.navy.mil/local/docs/pat-pubs/P-816.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-45 Flight training instruction&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircrew should pay particular attention to the A-sheet’s basic weight, fuel and store loads to ensure the gross weight calculation is correct. This is particularly important when launching from the boat because the catapult needs to be set correctly.... Taxiing up to the catapult, a green shirt will hold up the weight board. If the weight on the board matches the weight on the weight chit, acknowledge ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In case of steam catapults, the force, once set, is fixed; one advantage given for the Electromagnetic Aircraft Launch System (EMALS) is that the force could be adjusted by the system to keep the speed near the requirement. From &lt;a href=&quot;http://www.airspacemag.com/military-aviation/how-things-work-electromagnetic-catapults-14474260/?no-ist&quot; rel=&quot;nofollow noreferrer&quot;&gt;airspacemag&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The amount of steam needed to launch an airplane depends on the craft’s weight, and once a launch has begun, adjustments cannot be made:... The launch control system for electromagnetic catapults, on the other hand, will know what speed an aircraft should have at any point during the launch sequence, and can make adjustments during the process to ensure that an aircraft will be within 3 mph of the desired takeoff speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Carrier launches and recovery is one of the most stressful things the aircraft can undergo; however, the aircraft are designed to handle these, for example, via a strengthened landing gear and fuselage. Due to these, carrier aircraft have lifetimes comparable to that of land based aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carrier (in general, naval) environment is hostile to aircraft and as such, the maintenance schedule is different (and more extensive, for example checks for corrosion) in case of aircraft. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="16638" LastEditDate="2016-12-08T16:55:37.570" LastActivityDate="2016-12-08T16:55:37.570" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25089" PostTypeId="1" CreationDate="2016-02-10T00:38:18.803" Score="14" ViewCount="4168" Body="&lt;p&gt;Why is the coefficient of drag of a straight wing lower than the coefficient of drag of a swept back wing at higher supersonic speeds (above, say, Mach 2)?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="1961" LastEditDate="2016-03-30T07:51:31.460" LastActivityDate="2017-04-01T11:09:37.883" Title="Why is the coefficient of drag for straight wings at supersonic speeds lower than for swept wings?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;wing-sweep&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25090" PostTypeId="2" ParentId="25084" CreationDate="2016-02-10T07:49:42.997" Score="13" Body="&lt;h2&gt;Takeoff&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Steam/power settings are adjusted for each a/c type and T/O weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EMALS stores 484 MJ in four 121 MJ alternators spinning at 6400 rpm. It delivers up to 122 MJ over 91 m. That averages out to 300,000 lbf. EMALS more finely controls launch forces (Max Peak-to-Mean Tow Force Ratio = 1.05), allowing it to launch smaller a/c (eg, smaller UAVs) and delivering a smoother ride that reduces airframe fatigue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Current steam catapults deliver up to 95 MJ over 94 m. Each shot consumes up to 614 kg of steam piped from the reactor (NB: &lt;em&gt;not&lt;/em&gt; the primary coolant loop). That averages out to 230,000 lbf.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accelerations average around 3 g's, peak around 4 g's. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Landing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Landings are stressful (notice the fuselage skin wrinkling beneath the radome on this Hawkeye): &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AhPf3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AhPf3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:US_Navy_E-2C_Hawkeye_carrier_landing_fuselage_detail.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;: DoD photo by: PHAN KRISTOPHER WILSON, USN Date Shot: 11 Jan 2005.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An F/A-18 touches down around 720 fpm (12 ft/s). It's rated to twice that. CTOL fighters typically do about half that. I believe airliners average under 200 fpm (3 ft/s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here an F/A-18 is dropped from 20ft (36 ft/s, 2200 fpm): &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/pfzCwTwGTks?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;h2&gt;Service life&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;NATO fighters are typically designed for 30 year service lives (6,000 to 8,000 flight hours). Historically, Soviet/Russian fighters fly much less. The Su-27SK is rated for 2,000 flight hours over 20 years. [See &lt;a href=&quot;https://www.reddit.com/r/F35Lightning/comments/3c68tl/table_aircraft_cost_comparison/&quot; rel=&quot;noreferrer&quot;&gt;table for cost and service life comparison&lt;/a&gt;.] F/A-18's were built for 20 year service lives, 30 years with service life extensions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fuselage and landing gear are much stronger to withstand carrier landings and launches. The nose gear regularly transfers 4x the takeoff weight of the a/c into the rest of the fuselage. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare the F-35A's CTOL nose gear:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Z24TS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z24TS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.eglin.af.mil/news/story.asp?id=123265437&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;: USAF)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...to the F-35C's CATOBAR nose gear:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/iI5Pi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iI5Pi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.navair.navy.mil/index.cfm?fuseaction=home.NAVAIRNewsStory&amp;amp;id=5017&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;: USN)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here's an excerpt from a &lt;a href=&quot;http://carcamal.ele.cie.uva.es/CEM/articulos/Catapult.pdf&quot; rel=&quot;noreferrer&quot;&gt;Naval Air Warfare Center paper on EMALS&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Other drawbacks to the steam catapult include a high volume of 1133 m3&#xA;  , and a weight of 486 metric tons. Most of this is top-side weight&#xA;  that adversely impacts the ship's stability and righting moment. The&#xA;  large volume allocated to the steam catapult occupies &quot;prime&quot; real&#xA;  estate on the carrier. The steam catapults are also highly maintenance&#xA;  intensive, inefficient (4-6%), and their availability is low. Another&#xA;  major disadvantage is the present operational energy limit of the&#xA;  steam catapult, approximately 95 MJ. The need for higher payload&#xA;  energies will push the steam catapult to be a bigger, bulkier, and&#xA;  more complex system.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Endspeed:      28-103 m/s [54-200 knots]&#xA;Cycle time:    45 seconds&#xA;Weight       &amp;lt; 225,000 kg&#xA;Volume       &amp;lt; 425 m 3&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;  &#xA;  &lt;p&gt;At max speed, the output of one of the disk alternators would be 81.6&#xA;  MW into a matched load... These magnets have a residual induction of&#xA;  1.05 T at 40 oC and create an average working air gap flux density of 0.976 T, with tooth flux densities approaching 1.7 T... Maximum output voltage is 1700 V (L-L) peak and current is 6400 A peak per phase. The&#xA;  disk alternator's overall efficiency is 89.3%, with total losses of&#xA;  127 KW per alternator. This heat transfers out of the disk alternator&#xA;  through a cold plate on the outside of each stator. The coolant is a&#xA;  WEG mixture with a flow rate of 151 liters/minute. The average&#xA;  temperature of the copper is 84oC, while the back iron temperature is&#xA;  61oC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Sources:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.defenseindustrydaily.com/EMALS-Electro-Magnetic-Launch-for-Carriers-05220/&quot; rel=&quot;noreferrer&quot;&gt;EMALS/ AAG: Electro-Magnetic Launch &amp;amp; Recovery for Carriers&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.globalsecurity.org/military/systems/ship/systems/emals.htm&quot; rel=&quot;noreferrer&quot;&gt;Electromagnetic Aircraft Launch System - EMALS&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_catapult#Steam_catapults_types&quot; rel=&quot;noreferrer&quot;&gt;Steam catapult types&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://carcamal.ele.cie.uva.es/CEM/articulos/Catapult.pdf&quot; rel=&quot;noreferrer&quot;&gt;Electromagnetic Aircraft Launch System - EMALS - NAWC&lt;/a&gt; &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2016-02-10T13:20:13.510" LastActivityDate="2016-02-10T13:20:13.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25091" PostTypeId="1" CreationDate="2016-02-10T11:40:59.507" Score="4" ViewCount="160" Body="&lt;p&gt;This question is asked in context of a fixed wing, Unmanned Aerial Vehicle (UAV), with a wing span of about 5m (16ft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How far ahead of the wing leading edge should the propeller be located?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The propwash should have minimal effect on stability and should not adversely affect the airflow over the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can propwash be useful?&lt;/p&gt;&#xA;" OwnerUserId="11167" LastEditorUserId="12720" LastEditDate="2016-02-10T13:48:22.797" LastActivityDate="2016-02-10T13:48:22.797" Title="How far ahead of the wing should a propeller be located for a UAV?" Tags="&lt;propeller&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-02-18T10:37:35.743" ContentLicense="CC BY-SA 3.0" />
  <row Id="25093" PostTypeId="1" AcceptedAnswerId="25095" CreationDate="2016-02-10T12:56:50.263" Score="18" ViewCount="8357" Body="&lt;p&gt;Why did Great Britain develop three different planes - &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_Victor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Victor&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_Valiant&quot; rel=&quot;nofollow noreferrer&quot;&gt;Valiant&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Avro_Vulcan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vulcan&lt;/a&gt; - after WW2 for the same task? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that at that time the US and the Soviet Union were producing high numbers of bombers too, but did those countries stick to one design? Why did France not produce different bombers? My main question is about the effort of Great Britain and I am listing other countries only as examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the Handley Page Victor:&lt;a href=&quot;https://i.stack.imgur.com/eFTyJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eFTyJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Handley_Page_HP-80_Victor_K2_AN1103895.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the Vickers Valiant:&lt;a href=&quot;https://i.stack.imgur.com/rHYPL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rHYPL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_Valiant#/media/File:Vickers_valiant_camouflaged_on_ground_arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the Avro Vulcan:&lt;a href=&quot;https://i.stack.imgur.com/GGuVb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GGuVb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Avro_Vulcan#/media/File:Vulcan_Bomber_MOD_45133331.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="13431" LastEditDate="2016-03-12T22:05:57.033" LastActivityDate="2016-03-12T22:05:57.033" Title="Why did Britain develop three different bombers (V-bombers) after WW2 instead of one?" Tags="&lt;aircraft-design&gt;&lt;strategic-bomber&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25094" PostTypeId="2" ParentId="25093" CreationDate="2016-02-10T13:24:30.717" Score="16" Body="&lt;p&gt;After the end of WWII there was an awareness at the British air ministry that a new type of bomber would be needed for nuclear warfare against the USSR. The specification that the government put forward required radical designs and the government was concerned they might fail, so they decided to go forward with 3 of them to ensure they had a nuclear deterrent in place. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There was also likely politics involved. At the time Britain was one of the leaders of aviation design and production, it was one of the few things going right in Britain at the time. The government felt it was important to support that industry, even though it meant higher costs. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-10T13:24:30.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25095" PostTypeId="2" ParentId="25093" CreationDate="2016-02-10T14:29:44.110" Score="20" Body="&lt;p&gt;I've heard numerous reasons cited - perhaps due to the secrecy around all things nuclear - but from what I know, there are a few reasons:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Speed of deployment&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Of the three designs, the Valiant was simplest, and could therefore be built and deployed the soonest. The initial Valiant prototype didn't actually meet the requirements that had been set forth for a nuclear-capable bomber aircraft, but it was better than nothing and with the mounting threat that the Cold War might turn hot, this speed was an asset, so the requirements were changed to allow the Valiant to enter service. This would fill the gap in the UK's forces, and more advanced aircraft could follow later. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Specialisation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Each of the V-bombers had slightly different performance, meaning that they could perform slightly different roles.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Victor had the greatest payload capacity (up to 35 thousand-pound bombs)&lt;/li&gt;&#xA;&lt;li&gt;The Vulcan was smaller and more agile and could therefore use smaller runways, and could &lt;em&gt;just&lt;/em&gt; about break Mach 1 in a slight dive. It could also be refuelled in flight.&lt;/li&gt;&#xA;&lt;li&gt;The Valiant was the simplest design, and therefore the most reliable (although it later emerged that a newly-developed and poorly-understood alloy introduced some serious design flaws)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Spreading the risk&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Overall, the differences between the various aircraft were pretty minor, and the main reason that three contracts were allowed to progress to delivery was simple: the UK didn't want to put all their eggs in one aeroplane. The need for a nuclear deterrent - and a means to deliver it - was so great that it could not be jeopardised by a poorly-designed bomber, a mismanaged project, unforeseen failure of the company building the aircraft, etc. By having three aircraft from three different manufacturers, the UK greatly improved their chances of having at least one aircraft that actually worked, was delivered on time, and was able to remain in service for a reasonable period of time.&lt;/p&gt;&#xA;" OwnerUserId="4184" LastActivityDate="2016-02-10T14:29:44.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25096" PostTypeId="1" AcceptedAnswerId="25097" CreationDate="2016-02-10T15:24:45.830" Score="25" ViewCount="14902" Body="&lt;p&gt;Nowadays they are no longer needed but why do they cover them up like in this photo?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/MnXvt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MnXvt.jpg&quot; alt=&quot;737&quot;&gt;&lt;/a&gt;&#xA;What is their purpose and why aren't they used anymore?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://m.airliners.net/photo/detail/id/2008163&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2018-03-24T12:31:12.920" LastActivityDate="2018-04-01T03:23:15.767" Title="What is the purpose of eyebrow windows?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25097" PostTypeId="2" ParentId="25096" CreationDate="2016-02-10T15:50:39.427" Score="33" Body="&lt;p&gt;Wikipedia answers this on &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737#Flight_systems&quot;&gt;the Boeing 737 page&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Most 737 cockpits are equipped with &quot;eyebrow windows&quot; positioned above&#xA;  the main glareshield. Eyebrow windows were a feature of the original&#xA;  707 and 727. They allowed for greater visibility in turns, and&#xA;  offered better sky views if navigating by stars. With modern avionics,&#xA;  they became redundant, and many pilots actually placed newspapers or&#xA;  other objects in them to block out sun glare. They were eliminated&#xA;  from the 737 cockpit design in 2004, although they are still installed&#xA;  at customer request. These windows are sometimes removed and&#xA;  plugged, usually during maintenance overhauls, and can be&#xA;  distinguished by the metal plug which differs from the smooth metal in&#xA;  later aircraft that were not originally fitted with the windows.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2016-02-10T15:50:39.427" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25099" PostTypeId="1" CreationDate="2016-02-10T09:03:07.213" Score="8" ViewCount="214" Body="&lt;p&gt;I have a question about a document published by the Association of European Airliners. The name of the document is “Long Range Aircraft - AEA Requirements.” In the Appendix titled &quot;Definitions and Inputs for Range and DOC Calculation,&quot; paragraph 1.1 (“Flight Profile for DOC and Range Calculation”) at Note c) we can read the following recommendation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cruise, and completion of step, shall be at that altitude at which the potential rate of climb, at initial cruise weight-climb speed, is 500 ft./min or more&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't understand the meaning of that sentence. What’s the definition of “weight-climb speed?”&lt;/p&gt;&#xA;" OwnerUserId="13498" OwnerDisplayName="d.pensopositivo" LastActivityDate="2016-02-10T17:17:42.650" Title="What is weight-climb speed?" Tags="&lt;terminology&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25100" PostTypeId="2" ParentId="25083" CreationDate="2016-02-10T17:08:58.370" Score="4" Body="&lt;p&gt;&lt;strong&gt;&lt;em&gt;Note:&lt;/strong&gt; This answer is given for &lt;a href=&quot;/questions/tagged/faa-regulations&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;faa-regulations&amp;#39;&quot; rel=&quot;tag&quot;&gt;faa-regulations&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;Rotorcraft&lt;/code&gt; is an aircraft &lt;em&gt;category&lt;/em&gt;; &lt;code&gt;helicopter&lt;/code&gt; and &lt;code&gt;gyrocopter&lt;/code&gt; are &lt;em&gt;classes&lt;/em&gt; of the &lt;code&gt;rotorcraft&lt;/code&gt; &lt;em&gt;category&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longer Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt; defines aircraft Categories and Classes for airman certification, and gives examples of each. In these definitions &lt;code&gt;helicopter&lt;/code&gt; is included under &lt;em&gt;classes&lt;/em&gt;; &lt;code&gt;rotorcraft&lt;/code&gt; is included under &lt;em&gt;categories&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1, Category&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Category:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a broad classification of aircraft. Examples include: airplane; &lt;strong&gt;rotorcraft&lt;/strong&gt;; glider; and lighter-than-air;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1, Class&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) As used with respect to the certification, ratings, privileges, and limitations of airmen, means a classification of aircraft within a category having similar operating characteristics. Examples include: single engine; multiengine; land; water; gyroplane; helicopter; airship; and free balloon;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Elsewhere in chapter 14 of the CFR, helicopter is given as a class of the rotorcraft category, for example in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=240fddea648bce985de5daa723e48195&amp;amp;mc=true&amp;amp;node=se14.2.61_1161&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;§61.161&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§61.161   Aeronautical experience: Rotorcraft category and helicopter&#xA;  class rating.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) A person who is applying for an airline transport&#xA;  pilot certificate with a rotorcraft category and helicopter class&#xA;  rating, must have at least 1,200 hours of total time as a pilot that&#xA;  includes at least:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore, we see that &lt;code&gt;helicopter&lt;/code&gt; is a class and will not have any sub–classes. &lt;code&gt;Helicopter&lt;/code&gt; and &lt;code&gt;gyrocopter&lt;/code&gt; are the &lt;em&gt;classes&lt;/em&gt; of the &lt;code&gt;rotorcraft&lt;/code&gt; &lt;em&gt;category&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-02-10T17:08:58.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25102" PostTypeId="2" ParentId="25099" CreationDate="2016-02-10T17:17:42.650" Score="8" Body="&lt;p&gt;A cruise weight-climb is a climb segment during the cruise phase of the flight to achieve a higher flight level that was previously not reachable due the weight of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long range aircraft cannot climb as high initially because of the weight of the fuel they carry. Their operating ceiling is power limited. As the aircraft burns off weight during the flight, the drag decreases and gradually excess power becomes available for climbing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This recommendation is not to start climbing to the next level until a vertical climb speed of 500ft can be maintained at the new level, at the initial cruise speed after that weight-climb. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if the the cruise starts at FL270, and one wants to climb to FL290 for a cruise at Mach 0.80, the weight-climb should not start before the aircraft can maintain a 500 ft/min climb at Mach 0.80 at FL290. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2016-02-10T17:17:42.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25103" PostTypeId="1" AcceptedAnswerId="25106" CreationDate="2016-02-10T17:17:55.713" Score="30" ViewCount="8542" Body="&lt;p&gt;Many aircraft have this line above the door as seen in the photos below. What is it, and what is its purpose?&lt;br&gt;&#xA;&lt;a href=&quot;http://airwaysnews.com/galleries/american-airlines-boeing-777-300er-inaugural-arrives-at-sao-paulo-gru-1_26567.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/MC76F.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MC76F.jpg&quot; alt=&quot;777&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;http://training.deicinginnovations.com/?page_id=515&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8BCI5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8BCI5.jpg&quot; alt=&quot;777&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:14:19.277" LastActivityDate="2016-12-31T19:11:50.193" Title="What is this line found above the door on many aircraft?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;fuselage&gt;&lt;doors&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25104" PostTypeId="2" ParentId="25096" CreationDate="2016-02-10T17:28:02.053" Score="25" Body="&lt;p&gt;To add to Steve's correct answer, Boeing has historically designed aircraft with less than ideal visibility for the pilot. Case in point: Their first all-metal passenger aircraft, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_247&quot; rel=&quot;noreferrer&quot;&gt;Boeing 247&lt;/a&gt;. Its design was ahead of its time and prompted TWA to convince Douglas to build the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_DC-1&quot; rel=&quot;noreferrer&quot;&gt;DC-1&lt;/a&gt; and -2, but was marred by two details: The wing spar was not below the cabin floor level; instead, Boeing expected passengers to climb over the spar on their way to their seat. Many airlines were less enthusiastic and rejected the aircraft in favor of the DC-2 and -3, which also offered more seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second detail was the cockpit window: It was sloped forward, so the visibility in the upper hemisphere was severely restricted. In turns the pilots were basically flying blind. The idea was to angle the window glass such that the instrument lighting would not reflect in the glass, but Boeing soon realized that this was creating new problems, and from the 247D on the window was sloped aft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NGepn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NGepn.jpg&quot; alt=&quot;Boeing 247&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Forward fuselage of the Boeing 247 (picture &lt;a href=&quot;http://airminded.net/b247/b247a_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the 247 was offered to Lufthansa, it was rejected for this particular reason. I guess Boeing engineers were very sensitive to get the visibility right after the 247.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-10T20:46:15.393" LastActivityDate="2016-02-10T20:46:15.393" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25105" PostTypeId="2" ParentId="25103" CreationDate="2016-02-10T17:31:46.710" Score="15" Body="&lt;p&gt;It's for the passengers on a rainy day. If this strip would not be diverting the rainwater flowing from the upper fuselage, a curtain of water would soak the passengers upon entering or leaving the aircraft, and the cabin floor.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-10T17:31:46.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25106" PostTypeId="2" ParentId="25103" CreationDate="2016-02-10T17:32:30.673" Score="47" Body="&lt;p&gt;These are &lt;strong&gt;rain gutters&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are designed to catch rain that runs off the upper surface of the aircraft fuselage and channel it away from the open aircraft door so that the water does not enter the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a close up of the rain gutter over the main cabin door of a Beechcraft King Air B200, showing the channel that would catch and redirect water flow to the side of the door opening:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZaoOE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZaoOE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;Sup&gt;Source: own work&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A jet-bridge may partially deflect rainwater in some cases, but the gutter helps mitigate water exposure for the aircraft interior and passengers. Even gutters cannot completely eliminate such exposure since their size is necessarily limited by aerodynamic constraints. Many operations do not have the luxury of jet-bridges, making the rain gutter especially helpful in reducing the amount of water that might otherwise enter the cabin and pose a hazard to the aircraft or onboard systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Rain Gutters&quot; is the technical name, at least for Boeing aircraft, such as the B777 depicted in the photos in the question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a &lt;a href=&quot;http://787updates.newairplane.com/Boeing787Updates/media/Boeing787Updates/Aviation%20Experts/DesignChange_Bck_FINAL_1.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boeing reference&lt;/a&gt; to such gutters on the 787:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Rain gutter&lt;/strong&gt;: When customers found that water was not being properly deflected&#xA;  over a passenger entry door, they requested a change. Boeing relocated the&#xA;  gutter to function more efficiently. The solution means happy customers, who had&#xA;  fewer water and maintenance issues, and happier and drier passengers. This&#xA;  was a significant enough change to process to require certification work with the FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-10-09T19:58:19.987" LastActivityDate="2016-10-09T19:58:19.987" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25107" PostTypeId="1" AcceptedAnswerId="25109" CreationDate="2016-02-10T17:55:01.590" Score="12" ViewCount="9376" Body="&lt;p&gt;If you search around on the Internet, have an older copy of the Instrument Flying Handbook, or talk to a seasoned CFII, you may run across the concept of &quot;pattern a&quot; and &quot;pattern b.&quot; These were exercises which involved tracking courses, flying procedure turns, hold entries and sometimes constant speed climbs and descents. They seem like valuable maneuvers for honing instrument flying skills.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At some point in the last several years they seem to have been removed from the Instrument Flying Handbook. I don't actually own an out-of-date copy of the handbook to verify this, but if they were removed I'm wondering if anyone knows why. Does the FAA frown upon the use of these maneuvers in training?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Beyond the question itself, I'd love to find a current publication that teaches pattern a and pattern b for reference.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="3201" LastEditDate="2016-02-10T22:33:13.943" LastActivityDate="2017-10-25T20:08:47.820" Title="Why were &quot;pattern a&quot; and &quot;pattern b&quot; removed from the Instrument Flying Handbook?" Tags="&lt;flight-training&gt;&lt;instrument-flight-rules&gt;&lt;faa&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25108" PostTypeId="1" AcceptedAnswerId="25110" CreationDate="2016-02-10T18:18:11.530" Score="9" ViewCount="4276" Body="&lt;p&gt;The A320 doesn't have a dorsal fin, but the 737 does. If the 737 is more or less a similar aircraft, why doesn't the A320 have a similar dorsal fin?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/825Oj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/825Oj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;By Bill Larkins [&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/2.0&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 2.0&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File%3AUnited_Airlines_Airbus_A320_and_Boeing_737-800_on_final_approach_at_San_Francisco.jpg&quot; rel=&quot;noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="14897" LastEditDate="2017-08-27T16:41:41.293" LastActivityDate="2019-01-14T16:58:30.413" Title="Why doesn't the A320 have a dorsal fin like the 737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;&lt;vertical-stabilizer&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25109" PostTypeId="2" ParentId="25107" CreationDate="2016-02-10T19:11:33.367" Score="12" Body="&lt;p&gt;I can't say for sure, but I would assume that the pattern-based drills were removed because of the new emphasis on scenario-based (&quot;real world&quot;) training the FAA has been moving toward: While Pattern A and Pattern B are useful for honing your skills (and I'll even admit they're kind of fun to fly) they're not something you'll fly in the &quot;real world&quot; - you are unlikely to string together that particular set of elements in that particular order on any kind of regular basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That doesn't mean the Pattern A / Pattern B maneuvers are not useful tools or that the FAA &quot;frowns on&quot; them - they really don't care &lt;em&gt;how&lt;/em&gt; you acquire the skills necessary to pass your checkride and if flying Pattern A / Pattern B helps then by all means fly your heart out! Just know that when you take your checkride you will not be asked to &quot;Fly Pattern B&quot; - it's not an element of the practical test.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A copy of the maneuver diagrams for Pattern A and Pattern B can be found in Gleim's &lt;a href=&quot;http://www.gleim.com/public/pdf/av_updates/ipfmadd2.pdf&quot; rel=&quot;noreferrer&quot;&gt;Additional Instrument Flight Maneuvers&lt;/a&gt; handout, which also has some valuable notes on how the maneuvers should be performed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally I prefer the diagrams from &lt;a href=&quot;http://www.privilegeaero.com/instrument_flying_patterns.html&quot; rel=&quot;noreferrer&quot;&gt;Privilege Aero&lt;/a&gt; because I find them a little easier to read (Patterns A &amp;amp; B are listed as Patterns D &amp;amp; E respectively, except the Gleim version of Pattern B includes a descent &amp;amp; go-around at the end of the hold).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've reproduced the Pattern E diagram below in case any of the links above break.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/lLAyK.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lLAyK.jpg&quot; alt=&quot;Pattern &amp;quot;E&amp;quot; (Pattern B)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-02-10T19:37:05.700" LastActivityDate="2016-02-10T19:37:05.700" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25110" PostTypeId="2" ParentId="25108" CreationDate="2016-02-10T20:37:31.947" Score="3" Body="&lt;p&gt;Adding a dorsal fin, increases surface area. The plus theoretical side is that it increases directional stability. The minus theoretical side is that it adds weight, drag, and manufacturing complexity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early 737s did not have a dorsal fin. Presumably, at some point Boeing decided that adding one would provide better performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus apparently does not see the need for on in the A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are all design decisions.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-02-10T20:37:31.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25111" PostTypeId="2" ParentId="25108" CreationDate="2016-02-10T21:16:24.367" Score="15" Body="&lt;p&gt;Boeing learned the value of a dorsal strake the hard way: On their civilian version of the B-17, the &lt;a href=&quot;http://www.air-and-space.com/Boeing%20307%20N19903.htm&quot; rel=&quot;noreferrer&quot;&gt;Boeing 307 Stratoliner&lt;/a&gt;, the first Boeing aircraft with a pressurized cabin, the lack of a strake ahead of the fin caused the rudder to lock in the hard-over position when the pilot demonstrated the capability of the aircraft to fly with two dead engines on one side. The aircraft entered a spin and crashed, and that was on a demonstration flight for prospective customers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xDS5w.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xDS5w.jpg&quot; alt=&quot;Early Boeing 307 with the two right engines off and props feathered&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early Boeing 307 with the two right engines off and props feathered (picture &lt;a href=&quot;http://www.air-and-space.com/Boeing%20307/NX19901%20left%20front%20in%20flight%20two%20feathered%20props%20l.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note the deflected rudder and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/15779/why-do-airplanes-have-curved-windows/15781?s=3%7C0.0915#15781&quot;&gt;rectangular windows in a pressurized fuselage&lt;/a&gt;. It worked because the pressure difference was small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wo8T9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wo8T9.jpg&quot; alt=&quot;Late Boeing 307 in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Late Boeing 307 in flight (picture &lt;a href=&quot;http://www.air-and-space.com/Boeing%20307/Clipping%20NX1940%20TWA%20a%20l.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The vertical was enlarged and had the strake added; the same vertical was also used on later versions of the B-17.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With today's hydraulically operated controls the risk of an uncontrollable hard-over is reduced, but exactly this happened to &lt;a href=&quot;http://www.airlinesafety.com/faq/B-737Rudder.htm&quot; rel=&quot;noreferrer&quot;&gt;several early Boeing 737s&lt;/a&gt;. From the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Classic&quot; rel=&quot;noreferrer&quot;&gt;737-300&lt;/a&gt; on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14786/what-is-the-purpose-of-a-dorsal-fin-such-as-on-the-boeing-737&quot;&gt;strake was added&lt;/a&gt; and the control system (PCU = power control unit) was exchanged for a  modified version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airbus never had those issues and did not see the need to add a strake since the existing vertical could do its job in all conditions. A strake is worthless at small sideslip angles and will only help when the vertical is close to stalling due to extreme sideslip. Adding a strake will increase the wetted surface area and add friction drag, so Airbus did not include one.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-02-10T21:23:57.750" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25114" PostTypeId="2" ParentId="25044" CreationDate="2016-02-10T23:42:25.230" Score="6" Body="&lt;p&gt;This information is for the US, taken from &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FINAL%20FAA%20Order%206850.2B.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Order 6850 - Visual Guidance Lighting Systems&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;VASI (2 bar VASI for illustration, but other configurations exist)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;a. Layout&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C5jLA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C5jLA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;b. Aiming&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two-bar VASI system shall have the upwind bar aimed at three&#xA;  degrees and the downwind bar aimed one-half degree lower at 2.5&#xA;  degrees; however, where necessary to provide obstacle clearance, the&#xA;  downwind bar may be aimed at 2.75 degrees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;c. Glide (vertical) path angles&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XL39M.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XL39M.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;d. Horizontal field of view:&lt;/em&gt; 10°&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Determine the minimum aiming angle by plotting all objects within an&#xA;  area  established by two lines each diverging at 10 degrees from&#xA;  runway centerline extend to 4 nautical miles, and starting at the&#xA;  runway centerline at the number one bar.  A line drawn from the runway&#xA;  centerline at the number one bar at an angle that will clear the&#xA;  highest object by not less than one degree establishes the minimum&#xA;  aiming angle.  This line and a horizontal line perpendicular to the&#xA;  runway centerline at the number one bar (downwind) establishes an&#xA;  obstruction - clear plane 10 degrees (6 degrees in special&#xA;  applications where 10 degrees is not obtainable) on both sides on the&#xA;  extended runway centerline.  The obstruction clear plane starts at the&#xA;  number one bar and extends outward from the threshold for four&#xA;  nautical miles.  In addition, the minimum aiming angle shall be within&#xA;  the glide path limitations of paragraph 4. When less than 10 degrees&#xA;  are used for determining the obstruction-clear plane, issue a NOTAM&#xA;  and request publication in the Airport/Facilities Directory.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PAPI&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;a. Colocation with ILS glideslope&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When siting PAPI on a runway with an established electronic glide&#xA;  slope, the PAPI visual approach path should coincide, as much as&#xA;  possible, with the one produced electronically.  To accomplish this,&#xA;  the PAPI is placed at the same distance from the threshold as the&#xA;  virtual source of the electronic glide slope within a tolerance of ±30&#xA;  feet (±10 m).  The PAPI is aimed at the same angle as the electronic&#xA;  glide slope.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;b. Layout&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ottrO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ottrO.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;c. Aiming&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The visual glide path angle is the center of the on-course zone, and&#xA;  shall normally be 3 degrees when measured from the horizontal.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;d. Glide (vertical) path angles&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3kRvU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3kRvU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;e. Horizontal field of view:&lt;/em&gt; 10°&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The PAPI obstacle clearance surface is established to provide the&#xA;  pilot with a minimum clearance over obstacles during approach.  The&#xA;  PAPI must be positioned and aimed so that no obstacles penetrate this&#xA;  surface.  The surface begins 300 feet (90 m) in front of the PAPI&#xA;  system (closer to the threshold) and proceeds outward into the&#xA;  approach zone at an angle 1  degree less than the aiming angle of the&#xA;  third LHA from the runway.  For a 3 degrees glide path and 20 minutes&#xA;  separation between LHAs, the third LHA from the runway would be aimed&#xA;  at 2 degrees, 50 minutes elevation.  The surface extends 10 degrees on&#xA;  either side of the runway centerline extended, and extends 4 statute&#xA;  miles from its point of origin.  The surface is shown graphically in&#xA;  figure 5-4.  If a site survey determines that there is an obstacle,&#xA;  which penetrates the obstacle clearance surface and cannot be removed,&#xA;  then the glide path angle must be changed or the PAPI system moved&#xA;  further from the threshold.  By moving or re-aiming the PAPI, the PAPI&#xA;  obstacle clearance surface is repositioned so it will not be&#xA;  penetrated by an obstacle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4McnC.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4McnC.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-02-10T23:42:25.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25117" PostTypeId="1" AcceptedAnswerId="25121" CreationDate="2016-02-11T01:36:57.657" Score="8" ViewCount="4795" Body="&lt;p&gt;I couldn't find any image to show you what I'm talking about but on many aircraft there are markings around the static ports and the pitot probes that say RVSM Critical Area. What is this?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-02-11T03:00:16.033" Title="What are the RVSM Critical Area markings?" Tags="&lt;aircraft-design&gt;&lt;aircraft-marking&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25118" PostTypeId="1" CreationDate="2016-02-11T01:49:07.057" Score="0" ViewCount="972" Body="&lt;p&gt;It is a well known statistic that rear seats has higher survivability rates than front seats due to generally lower impact forces. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Double decks airplanes are not so common so statistics would probably be unreliable, especially since Boeing's only have a forward double deck. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has any survivability study been made on that kind of aircraft, that include upper vs lower deck ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly interested in the a380 but other design are welcome as well. &lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="4105" LastEditDate="2016-02-11T02:48:46.560" LastActivityDate="2016-02-11T08:09:00.823" Title="Safest deck on multi deck airplanes" Tags="&lt;safety&gt;&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2016-02-11T11:24:43.713" ContentLicense="CC BY-SA 3.0" />
  <row Id="25120" PostTypeId="2" ParentId="25117" CreationDate="2016-02-11T02:52:06.910" Score="10" Body="&lt;p&gt;The RVSM critical areas must be inspected prior to every flight to ensure they are free from debris, deformation, or other damage. This is to ensure the altimetric accuracy of the pitot/static system for operation in RVSM airspace. This inspection is typically done by a pilot during their pre-flight walk-around.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-02-11T03:00:16.033" LastActivityDate="2016-02-11T03:00:16.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25121" PostTypeId="2" ParentId="25117" CreationDate="2016-02-11T02:57:05.453" Score="14" Body="&lt;p&gt;Aircraft need to know their altitudes to avoid bumping into each other in the vertical dimension. The default instrument for this is a pressure altimeter. A pressure altimeter needs access to a static port. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;RVSM stands for Reduced Vertical Separation Minima. Basically, aircraft above a certain altitude (29,000 ft) used to be kept further apart from each other vertically (2000 ft) since the accuracy of the pressure altimeters degrades with altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the years, as traffic density increased there was a need to pack aircraft closer vertically (1000 ft). This is possible if you have a special more accurate altimeter system in all aircraft and these ops are RVSM (late 1990's and early 2000's). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, in order to guarantee that this system works as designed several points need to be satisfied one of which is the integrity of that static port I mentioned earlier. Static ports can be sensitive to external air flow and hence any variation / disturbance / abnormality in the area immediately adjacent to them on the fuselage must be avoided whenever you want to use the aircraft for RVSM operations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And hence the markings to serve as a guide to all involved in aircraft ops about which is the area to worry about. e.g. Any imperfection in that region will have to be dealt with immediately. And worst case the aircraft would not be capable of flying in RVSM operations till any problems are fixed. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2016-02-11T02:57:05.453" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25123" PostTypeId="2" ParentId="25118" CreationDate="2016-02-11T08:09:00.823" Score="1" Body="&lt;p&gt;Very difficult to say as we don't have enough real-world examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical impact forces would be lower on the upper deck as the lower deck acts something like a crumple zone and absorbs some of the acceleration.&#xA;That said, an evacuation from the upper deck can result in more injuries due to the longer, steeper, slide that's needed.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-02-11T08:09:00.823" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25124" PostTypeId="1" CreationDate="2016-02-11T08:55:22.640" Score="2" ViewCount="157" Body="&lt;p&gt;I saw that discussions were going on for EASA to approve single engine turbine airplanes for IFR commercial operations. Anybody knows the current status? Where can I find it? Is it going ever to happen? Another question is how big impact this is going to make? Are SAT much more efficient and cheaper to run than multi engine aircraft? &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-02-11T08:55:22.640" Title="Will EASA approve single engine IFR commercial operations any time soon? Will this be a big impact on the industry?" Tags="&lt;instrument-flight-rules&gt;&lt;easa-regulations&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-02-11T15:02:59.183" ContentLicense="CC BY-SA 3.0" />
  <row Id="25125" PostTypeId="1" CreationDate="2016-02-11T09:25:45.020" Score="5" ViewCount="4574" Body="&lt;p&gt;In the IATA &lt;a href=&quot;https://www.iata.org/publications/Pages/airport-handling-manual.aspx&quot; rel=&quot;nofollow&quot;&gt;Airport Handling Manual procedures&lt;/a&gt;, messages are send to communicate with the transit station to describe the cargo load. The &lt;a href=&quot;http://wiki.aviabit.ru/images/4/49/AHM583.pdf&quot; rel=&quot;nofollow&quot;&gt;Load message LDM&lt;/a&gt; (AHM 583) is sent primarily to enable the transit station to know in advance the load which continues on the same aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;LDM ZZ999/13.ZZOEA.Y136.2/4&lt;br&gt;&#xA;  -SHJ.15/22/3/1.T1500.3/1000.4/500.PAX/40.PAD/0&lt;br&gt;&#xA;  -CMB.27/22/12/3.T3500.1/2800.5/700.PAX/61.PAD/0 SI&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In here we got  hold id 3 total gross weight 1000kg,...&#xA;In our automated system, we need info in compartment bay level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can we get those information?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any other message like Container / Pallet Distribution Message CPM (AHM 587)?&lt;/li&gt;&#xA;&lt;li&gt;Or we have to manage manually (should distribute by load controller) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13451" LastEditorUserId="19" LastEditDate="2016-08-12T10:56:17.577" LastActivityDate="2016-08-12T10:56:17.577" Title="How can compartment bay loading informating be derived from the IATA load message (LDM)?" Tags="&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25126" PostTypeId="2" ParentId="25039" CreationDate="2016-02-11T09:30:36.740" Score="10" Body="&lt;p&gt;In fact, ARINC 429 is used in the &quot;federated&quot; avionics, this is the &quot;old&quot; system used in many aircraft like A320, B737, ...&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Federated avionics require a lot of wires which generates a lot of weight. In ARINC we have approximately one wire per device, so the speed (100Kbps or 12,5Kbps depending on the selected mode) is sufficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ARINC 429 Architecture :&#xA;&lt;a href=&quot;https://i.stack.imgur.com/D1M56.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/D1M56.png&quot; alt=&quot;ARINC 429 Architecture&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In &quot;new&quot; aircraft like A350 or B787 the industry use the Integrated Modular Avionics in order to reduce weight and reduce the number of S/N to stock.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In this kind on avionic all computers are merged in a couple of &quot;cabinet&quot; composed of multiple core processor units, shared ROM, shared RAM, shared graphic cards.&lt;/li&gt;&#xA;&lt;li&gt;All these cards are linked, in the cabinet, with the Backplane BUS (ARINC 659), which operates at 60Mbps as a commercial aviation bus&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;All cabinet are linked ,each other and with actuators, using AFDX (ARINC 664) who look like Ethernet protocol and work at the speed of 100Mbit/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a lot of different IMA architecture with the same principle, but some differences. This is one on them, in this picture you can replace PCI Ex. by ARINC 659 :&#xA;&lt;a href=&quot;https://i.stack.imgur.com/bsun7.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bsun7.png&quot; alt=&quot;IMA architecture&quot;&gt;&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Regarding CAN bus, Airbus use in in this A380 (&lt;a href=&quot;http://www.aviationtoday.com/av/issue/feature/can-bus-in-aviation_31468.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.aviationtoday.com/av/issue/feature/can-bus-in-aviation_31468.html&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sources : &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.interfacebus.com/Design_Connector_Avionics.html&quot; rel=&quot;noreferrer&quot;&gt;http://www.interfacebus.com/Design_Connector_Avionics.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.modern-avionics.com/&quot; rel=&quot;noreferrer&quot;&gt;http://www.modern-avionics.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3039" LastActivityDate="2016-02-11T09:30:36.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25127" PostTypeId="1" CreationDate="2016-02-11T11:24:58.980" Score="3" ViewCount="1018" Body="&lt;p&gt;As the aircraft is too far from antennas and units, how do they be aware of weather changes or weather information along their route, or on the destination and alternate airports? &lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-06-13T10:42:39.833" Title="How does a pilot receive weather information when overflying the oceans?" Tags="&lt;weather&gt;&lt;navigation&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25129" PostTypeId="1" AcceptedAnswerId="25130" CreationDate="2016-02-11T15:56:05.753" Score="8" ViewCount="680" Body="&lt;p&gt;Some airports have a non-standard traffic pattern altitude.  For example KGXY is 800 feet.  Why is this?&lt;/p&gt;&#xA;" OwnerUserId="651" LastActivityDate="2016-02-12T07:28:27.993" Title="Why do some airports have a non standard traffic pattern altitude?" Tags="&lt;airport&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25130" PostTypeId="2" ParentId="25129" CreationDate="2016-02-11T16:03:20.593" Score="3" Body="&lt;p&gt;Airports underneath controlled airspace may need to keep their traffic clear of controlled airspace, which may start from a typical altitude such as 1000Ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As is also mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/a/9015/524&quot;&gt;this answer&lt;/a&gt;, in April 2013 the standard pattern height was changed from 800 ft to 1000ft, possibly accounting for a number of airports still having the old &quot;standard&quot;.&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-02-12T07:28:27.993" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25132" PostTypeId="1" CreationDate="2016-02-11T17:19:59.003" Score="2" ViewCount="534" Body="&lt;p&gt;Generally supersonic fighters have convergent - divergent nozzles. What is type of nozzle used in MiG-21 and MiG-27?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also please explain that how in a convergent nozzle where the max velocity in the nozzle is limited to one mach , how can the ac still go supersonic??&lt;/p&gt;&#xA;" OwnerUserId="13454" LastEditorUserId="13454" LastEditDate="2016-02-12T16:29:18.350" LastActivityDate="2016-02-14T12:09:31.797" Title="What is the type of nozzle used on the MiG-21 and MiG-27?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-02-14T13:52:14.470" ContentLicense="CC BY-SA 3.0" />
  <row Id="25133" PostTypeId="1" AcceptedAnswerId="25134" CreationDate="2016-02-11T17:20:24.193" Score="5" ViewCount="2680" Body="&lt;p&gt;I've seen some green &quot;bags&quot; on the SSJ100 when they were building it. What is the purpose of these?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wwZhE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wwZhE.jpg&quot; alt=&quot;ssj100&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-19T02:34:18.350" LastActivityDate="2016-02-19T02:34:18.350" Title="What are these green &quot;bags&quot; on the SSJ100?" Tags="&lt;aircraft-design&gt;&lt;fuselage&gt;&lt;plane-construction&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25134" PostTypeId="2" ParentId="25133" CreationDate="2016-02-11T18:24:29.260" Score="14" Body="&lt;p&gt;That's cabin insulation - probably fiberglass.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not always in green bags (blankets), and not always fiberglass, but some kind of insulation is necessary to help control temperature and reduce cabin noise (air moving over the fuselage is REALLY loud).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some other photos of different types of insulation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qCIND.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qCIND.jpg&quot; alt=&quot;Fiberglass&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Basic fiberglass with a plastic backing, cut to fit.&lt;br&gt;&#xA;Fiberglass with either plastic or foil backings is commonly used because it is both light and inherently flame-retardant (as long as the backing is fireproof it will not burn).  &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lJGoGm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lJGoGm.jpg&quot; alt=&quot;Soundex&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/C7GlEm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C7GlEm.jpg&quot; alt=&quot;Soundex composition&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Soundex - a sandiwch of acoustic foam, thermal insulating foam and aluminum foil - is a popular choice on propeller aircraft: Slightly heaver than fiberglass, but better at dampening sound.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sCMmf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sCMmf.jpg&quot; alt=&quot;Foam padding&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Foam padding (similar to the foam used under carpets) does a decent job at both sound and thermal insulation. In this case it's green &amp;amp; has no covering, but colors and coverings vary.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zGFQ5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zGFQ5.jpg&quot; alt=&quot;777 insulation blankets&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Prefabricated insulation blankets on a Boeing 777.&lt;br&gt;&#xA;(I believe these are fiberglass sealed in polyethylene, they're manufactured to fit each bay without cutting which avoids loose insulation material floating around).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-02-11T18:24:29.260" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="25136" PostTypeId="1" AcceptedAnswerId="25278" CreationDate="2016-02-11T21:22:03.813" Score="5" ViewCount="3486" Body="&lt;p&gt;The other day I made a &lt;a href=&quot;https://aviation.stackexchange.com/questions/25013/why-is-the-front-part-of-the-engine-not-painted&quot;&gt;question&lt;/a&gt; about the engine painting and why it isn't painted at the front part. The answer was: to facilitate anti-ice system. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/l8A08.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l8A08.jpg&quot; alt=&quot;787&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://fevergeon.com/aerospace/&quot; rel=&quot;nofollow noreferrer&quot;&gt;fervegeon.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So perhaps the leading edge of the horizontal and vertical stabilizer have a sort of anti-ice system?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this is not only on the 787; the 777 also has the leading edges unpainted.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eS7pz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eS7pz.jpg&quot; alt=&quot;777&quot;&gt;&lt;/a&gt; &#xA;&lt;a href=&quot;http://training.deicinginnovations.com/?p=2565&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And on the 757 and winglet.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/djE3H.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/djE3H.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;https://www.flickr.com/photos/sfphotocraft/15275093479&quot; rel=&quot;nofollow noreferrer&quot;&gt;flickr&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-04-14T18:26:34.217" Title="Why are the leading edges of the 787's horizontal and vertical stabilizers not painted?" Tags="&lt;aircraft-design&gt;&lt;anti-ice&gt;&lt;paint&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25137" PostTypeId="1" CreationDate="2016-02-11T22:11:38.060" Score="7" ViewCount="1241" Body="&lt;p&gt;As far as I know in a car engine the ECU can adjust fuel mass flow through every injector. I don't know the exact algorithm but probably engine roughness is monitored. Of course this is not possible in a jet engine. What will happen if an injector starts to malfunction? I assume it will be quite difficult to detect and a slight decrease in maximum power will appear. But engines usually are not run at full power? Can this be dangerous when maximum performance is needed (like engine failure at V1)? How are injectors tested in engines with mechanical fuel control? Can FADEC monitor fuel injectors?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="1696" LastEditDate="2016-02-11T22:24:20.553" LastActivityDate="2017-11-05T18:46:13.350" Title="How are fuel injectors in a jet engine monitored to detect malfunction?" Tags="&lt;jet-engine&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25138" PostTypeId="1" AcceptedAnswerId="25139" CreationDate="2016-02-11T23:51:12.817" Score="15" ViewCount="4942" Body="&lt;p&gt;On commercial flights do the pilots ever turn off the APU? Is it needed when flying?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-24T22:48:49.057" LastActivityDate="2016-02-25T17:39:20.873" Title="When do commercial flights turn off the APU?" Tags="&lt;airline-operations&gt;&lt;pilots&gt;&lt;apu&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25139" PostTypeId="2" ParentId="25138" CreationDate="2016-02-12T01:08:13.383" Score="24" Body="&lt;p&gt;This varies due to operational need and airline standard operating procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On my aircraft (an &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_E-Jet_family&quot; rel=&quot;noreferrer&quot;&gt;Embraer E-Jet&lt;/a&gt;) we turn on the APU roughly ten minutes prior to pushback and shut it down shortly after starting the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we plan on taxiing on one engine we will shut it down after the first engine start and perform a cross-bleed start on the second engine. Other operators leave the APU running for second engine start.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If performance requirements demand the engine bleed to be off for takeoff we will leave the APU on until after takeoff to provide cabin pressurization until the engine bleeds come back online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We typically leave the APU off for the remainder of the flight and do not turn it back on until the next flight, unless ground power is unavailable or unreliable at the destination, in which case we will turn it on after landing as we approach the gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The APU can also be left on (or started in flight) to assist with various abnormal or emergency situations where bleed air or electrical power generation might be needed. Each APU installation will have a different flight envelope in which it can be started / used and is specified in the aircraft's operational limitations.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="5517" LastEditDate="2016-02-25T17:39:20.873" LastActivityDate="2016-02-25T17:39:20.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25140" PostTypeId="1" AcceptedAnswerId="25155" CreationDate="2016-02-12T01:09:24.300" Score="5" ViewCount="2281" Body="&lt;p&gt;What is this metal plate for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ty5Ck.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ty5Ck.jpg&quot; alt=&quot;aircraft door&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://fr.freeimages.com/premium/aircraft-door-933182&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also see it here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SCysq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SCysq.jpg&quot; alt=&quot;aircraft&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://www.flickr.com/photos/martinmontingelli/3376670289&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is found on many aircraft so what is that piece of metal right there?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="15982" LastEditDate="2017-06-10T00:18:23.677" LastActivityDate="2017-06-10T00:18:23.677" Title="What is this metal plate below the door?" Tags="&lt;aircraft-design&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25141" PostTypeId="1" AcceptedAnswerId="25149" CreationDate="2016-02-12T01:14:04.037" Score="2" ViewCount="2121" Body="&lt;p&gt;Let's say someone wants to start doing some flight training in the United States with the eventual goal of receiving a private pilot certificate. They have yet to get a medical certificate or student pilot certificate. Can they go ahead and start getting some flight training logging dual received?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="755" LastEditDate="2016-02-12T05:16:00.137" LastActivityDate="2016-02-12T05:27:21.217" Title="Can a student pilot start flight training before they get their student pilot certificate and medical?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25142" PostTypeId="1" AcceptedAnswerId="25161" CreationDate="2016-02-12T01:19:54.130" Score="13" ViewCount="2728" Body="&lt;p&gt;I was watching &lt;a href=&quot;https://www.youtube.com/watch?v=M_oyBC5RIj8&quot;&gt;this video about the MD-83 magnetic compass&lt;/a&gt; and I found it interesting that it's designed the way it is. I'm not sure which of the airplanes in this series featured this strange arrangement, but it was the case on at least the MD-80 and MD-83.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The magnetic compass on these machines was located behind the first officer's seat and a series of mirrors were used to make it visible to the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why was it built this way? Were there any advantages to it? Did they go back to a more conventional design in later models?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="14897" LastEditDate="2016-09-06T22:16:45.090" LastActivityDate="2016-09-06T22:16:45.090" Title="Why is the MD-80 magnetic compass behind the first officer's seat?" Tags="&lt;aircraft-design&gt;&lt;md-80&gt;&lt;dc-9-family&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25143" PostTypeId="1" CreationDate="2016-02-12T01:21:28.570" Score="6" ViewCount="1485" Body="&lt;p&gt;Why does the critical angle of attack reduce with increasing mach number or What is the effect of compressibility on critical angle of attack?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="19" LastEditDate="2016-07-11T08:43:23.587" LastActivityDate="2020-04-18T05:31:57.747" Title="How does compressibility affect the critical angle of attack?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25144" PostTypeId="1" CreationDate="2016-02-12T01:22:49.353" Score="5" ViewCount="648" Body="&lt;p&gt;AC electrical buses are common in airplanes from light piston twins all the way up to the largest airliners. I usually see both a 115v and 36v AC bus with a 400 Hz output frequency. How do most airplanes regulate the output frequency coming from the AC generator?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2016-04-30T07:35:09.173" Title="How do airplanes regulate the output frequency of AC generators?" Tags="&lt;aircraft-systems&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25145" PostTypeId="1" CreationDate="2016-02-12T01:25:25.147" Score="7" ViewCount="286" Body="&lt;p&gt;A hung landing gear is a potentially disastrous situation for a pilot flying a general aviation piston aircraft. During &quot;shop talk&quot; I've heard people say that the best thing to do is cycle the gear. During my multi-engine check ride I was told emphatically by my examiner that cycling a hung was the wrong thing to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are some of the more common procedures suggested in POH/AFM documents for this situation? Can any deeper understanding be extracted from the common procedures?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="100" LastEditDate="2020-05-11T09:48:29.790" LastActivityDate="2020-05-11T09:48:29.790" Title="What are some of the more common procedures when faced with a hung landing gear?" Tags="&lt;landing-gear&gt;&lt;emergency-procedures&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25146" PostTypeId="1" AcceptedAnswerId="25153" CreationDate="2016-02-12T01:36:19.337" Score="4" ViewCount="8346" Body="&lt;p&gt;How does a True Airspeed Indicator work?&lt;br&gt;&#xA;I am aware of how the air speed indicator works, but how is the density input being provided to this instrument?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="19" LastEditDate="2016-07-11T08:43:58.977" LastActivityDate="2016-07-11T08:43:58.977" Title="How does a true airspeed indicator work?" Tags="&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25147" PostTypeId="2" ParentId="25145" CreationDate="2016-02-12T01:36:47.797" Score="11" Body="&lt;p&gt;As referenced in a comment, the generally accepted thing to do is to refer to the aircraft emergency checklist/AFM to see what it says to do.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will vary by aircraft design, but usually involves testing the indicator lights, and then activating alternate means of extending the gear as needed.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-02-12T01:36:47.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25149" PostTypeId="2" ParentId="25141" CreationDate="2016-02-12T02:58:52.067" Score="4" Body="&lt;p&gt;Yes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=e4677176569114f75598116a99e28e15&amp;amp;node=14:2.0.1.1.2.3.1.4&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.87(n)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(n) Limitations on student pilots operating an aircraft in solo flight. A student pilot may not operate an aircraft &lt;strong&gt;in solo flight&lt;/strong&gt; unless that student pilot has received: &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) An endorsement from an authorized instructor on his or her student pilot certificate for the specific make and model aircraft to be flown; and &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) An endorsement in the student's logbook for the specific make and model aircraft to be flown by an authorized instructor, who gave the training within the 90 days preceding the date of the flight. &lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?type=simple;c=ecfr;cc=ecfr;sid=85f2f758c7572cf6fd784c355d1c55a1;idno=14;region=DIV1;q1=61.23;rgn=div8;view=text;node=14%3A2.0.1.1.2.1.1.17&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.23(a)(3)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Operations requiring a medical certificate. Except as provided in paragraphs (b) and (c) of this section, a person— ...  &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(3) Must hold at least a third-class medical certificate— &lt;/p&gt;&#xA;    &#xA;    &lt;blockquote&gt;&#xA;      &lt;p&gt;(i) When exercising the privileges of a private pilot certificate; &lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;(ii) When exercising the privileges of a recreational pilot certificate; &lt;/p&gt;&#xA;      &#xA;      &lt;p&gt;&lt;strong&gt;(iii) When exercising the privileges of a student pilot certificate;&lt;/strong&gt;&lt;/p&gt;&#xA;    &lt;/blockquote&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The student pilot only needs a student pilot certificate and medical when operating in solo flight.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With that said, if there is any doubt that a medical certificate won't be granted it is a good idea to get that out of the way before spending money on flight training you will never be able to use.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="755" LastEditDate="2016-02-12T05:27:21.217" LastActivityDate="2016-02-12T05:27:21.217" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25150" PostTypeId="1" AcceptedAnswerId="25164" CreationDate="2016-02-12T04:00:50.700" Score="6" ViewCount="318" Body="&lt;p&gt;How does the voice in landing phase figure out the altitude from the runway? Is it reading the altitude from altimeter or totally separate system? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How accurate is the reading? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where is the reference point for altitude measurement? is it from landing gears? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="3386" LastEditDate="2016-02-12T15:16:56.730" LastActivityDate="2016-02-12T19:07:06.213" Title="How does terrain alert system work?" Tags="&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25151" PostTypeId="1" CreationDate="2016-02-12T04:57:37.750" Score="5" ViewCount="978" Body="&lt;p&gt;What are the relative noise levels in various aviation scenarios for observers seated inside an aircraft? I'm sure the specifics depend on model but I'm curious if any general trends can be drawn that are model agnostic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;e.g. Let's consider the following cases for a start:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Jet aircraft e.g. 747&lt;/li&gt;&#xA;&lt;li&gt;Jet aircraft gliding with all engines out&lt;/li&gt;&#xA;&lt;li&gt;Helicopter&lt;/li&gt;&#xA;&lt;li&gt;Glider&lt;/li&gt;&#xA;&lt;li&gt;Jet aircraft with noise insulation removed&lt;/li&gt;&#xA;&lt;li&gt;Piston driven prop. aircraft&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;We could rate on an arbitrary 1 to 100 (noisiest) scale. Even better, in case data is available, I'd love to see the dB values. (@vortaq7's comment below)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose speed will matter so we can probably use their typical cruise conditions for each case?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One motivation is to tease apart contributions from engine vs aerodynamic noise. Another is to quantify the effectiveness of sound insulation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose most of us never get a chance to really hear an all engines out jet nor to fly in a jet with no sound proofing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. This question was motivated by some comments here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/25133/what-are-these-green-bags-on-the-ssj100/25134?noredirect=1#comment59195_25134&quot;&gt;What are these green &amp;quot;bags&amp;quot; on the SSJ100?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-06-24T16:25:17.753" Title="What are the relative internal noise levels in various aircraft?" Tags="&lt;airliner&gt;&lt;jet&gt;&lt;noise&gt;&lt;noise-reduction&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25152" PostTypeId="1" AcceptedAnswerId="27034" CreationDate="2016-02-12T05:56:40.253" Score="6" ViewCount="424" Body="&lt;p&gt;Got my Private about 6 months ago, and I've always wondered - let's say I request a VFR departure to the South, with the active runway being, say, 2. Some towers will give my departure clearance in reference to the requested compass direction, i.e.&#xA;    &lt;code&gt;cleared for takeoff runway 2, right turn to heading 180 approved&lt;/code&gt;&#xA;whereas other towers will reference it to a pattern leg, such as &lt;code&gt;cleared for takeoff runway 2, right downwind departure approved&lt;/code&gt;. Similarly, I've noticed pilots based at airports that use the latter convention will follow that convention when making their departure requests. Is there any rhyme or reason behind which convention a tower follows?&lt;/p&gt;&#xA;" OwnerUserId="1736" LastEditorUserId="572" LastEditDate="2016-02-12T06:55:47.730" LastActivityDate="2016-04-18T10:56:29.297" Title="Why do some towers reference departures by compass direction, others by leg of pattern?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;phraseology&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25153" PostTypeId="2" ParentId="25146" CreationDate="2016-02-12T05:56:46.037" Score="5" Body="&lt;p&gt;For a basic True Airspeed Indicator (TAS Meter) like the one shown below, you simply dial your pressure altitude into the top window using the knob (aligning it with the appropriate temperature mark at the bottom of that window), and then read your true airspeed in the other window at the bottom.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nfiXM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nfiXM.png&quot; alt=&quot;TAS indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your pressure altitude can be obtained by setting your altimeter to 29.92 and reading the indication, the air temperature can be obtained from an outside air temperature (OAT) gauge (or you can use one from the Winds Aloft forecast if your aircraft does not have an OAT gauge), and the combination of the two gives you your density altitude.&lt;br&gt;&#xA;The meter itself is simply a mechanical slide rule, performing the same functions as you could do manually on an E6B flight computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The indicator above is showing a true airspeed of about 202 MPH, at a pressure altitude of 10,000 feet and a temperature of -15 degrees.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For a nice video tutorial &lt;a href=&quot;https://youtu.be/Qd1oCqzJZPM?t=17&quot; rel=&quot;nofollow noreferrer&quot;&gt;check out this one from the University of Oklahoma&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-02-13T23:46:38.593" LastActivityDate="2016-02-13T23:46:38.593" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25154" PostTypeId="2" ParentId="25143" CreationDate="2016-02-12T06:15:03.780" Score="4" Body="&lt;p&gt;First, I have to define what the critical angle of attack is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aerodynamicist speaks of critical conditions, he or she means the condition when the speed of sound is reached locally. The critical Mach number is the speed, measured in multiples of the speed of sound, when the top local speed in a flow field equals the speed of sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The critical angle of attack is the one when the local flow speed first reaches the speed of sound. Since it depends on the initial flow speed, it is only valid for a given flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Two parameters are responsible for the local increase in speed: Thickness and angle of attack. A body needs to displace air, so the air will squeeze around it, speeding up in the process (or &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430?r=SearchResults&amp;amp;s=2%7C10.9590#57430&quot;&gt;slowing down&lt;/a&gt; in fully supersonic flow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the angle of attack is increased, the stagnation point moves below the airfoil nose so the air flowing over the top of the wing needs to negotiate its leading edge first. This speeds it up and leads to a suction peak. Another view of the same phenomenon is that &lt;a href=&quot;https://aviation.stackexchange.com/questions/16193/how-do-wings-generate-lift/16202?s=5%7C0.0405#16202&quot;&gt;increasing suction on the upper side of the airfoil&lt;/a&gt; will accelerate the air flowing towards it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a higher flight speed, less local flow acceleration can be tolerated before the critical conditions are reached. There is even a maximum speed in that suction region of high local curvature that will not be exceeded in subsonic flight and which &lt;a href=&quot;https://aviation.stackexchange.com/questions/64785/aerodynamic-advantage-of-blunt-noses-and-why-subsonic/64811?r=SearchResults&amp;amp;s=1%7C4.3741#64811&quot;&gt;limits the maximum possible lift coefficient&lt;/a&gt;. Higher flight speed leaves less margin, so the angle of attack for maximum lift is reduced with increasing flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If by critical angle of attack you mean the one where maximum lift is reached (conventionally called stall angle of attack), please &lt;a href=&quot;https://aviation.stackexchange.com/questions/61218/whats-the-theoretical-background-of-the-critical-angle-of-attack/73447#73447&quot;&gt;read here&lt;/a&gt; how it can be influenced. Depending on the flight Mach number, flight speed should be increased or decreased to maximize it.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-04-18T05:31:57.747" LastActivityDate="2020-04-18T05:31:57.747" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25155" PostTypeId="2" ParentId="25140" CreationDate="2016-02-12T06:33:16.650" Score="11" Body="&lt;p&gt;@Greg is correct. It is a scuff plate, to protect the fuselage from damage due to GSE (like jetbridge etc). The image below shows it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hxlDS.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hxlDS.jpg&quot; alt=&quot;Scuff plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.slideshare.net/BPancho/13-master-configuration-deviation-list-a320&quot; rel=&quot;noreferrer&quot;&gt;slideshare.net&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The image below shows an example made out of Ti from a manufacturer's site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OZZcj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OZZcj.jpg&quot; alt=&quot;scuff plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.exoticmetals.com/products/aircraftstructuralcomponents/&quot; rel=&quot;noreferrer&quot;&gt;exoticmetals.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-02-12T06:46:28.483" LastActivityDate="2016-02-12T06:46:28.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25157" PostTypeId="2" ParentId="25144" CreationDate="2016-02-12T06:58:24.210" Score="2" Body="&lt;p&gt;It's done using mechanical device called &lt;a href=&quot;https://en.wikipedia.org/wiki/Constant_speed_drive&quot; rel=&quot;nofollow&quot;&gt;constant speed drive&lt;/a&gt;. Works almost the same as CVT transmission in a cars. The more complex thing is phase adjustment as airplane usually has multiple engines and generators. But that is not done as different generators always power different buses! &lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="753" LastEditDate="2016-02-12T10:57:35.127" LastActivityDate="2016-02-12T10:57:35.127" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25158" PostTypeId="1" CreationDate="2016-02-12T10:21:03.087" Score="13" ViewCount="888" Body="&lt;p&gt;In relation with &lt;a href=&quot;https://aviation.stackexchange.com/questions/25099/what-is-weight-climb-speed&quot;&gt;What is weight-climb speed?&lt;/a&gt;, why is it not a good idea to climb higher than a level at which you would have a cruise weight-climb speed less than 500 ft/min?&lt;/p&gt;&#xA;" OwnerUserId="13462" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-12T13:20:02.940" Title="Why is it not a good idea to climb higher than a level at which you would have a cruise weight-climb speed less than 500 ft/min?" Tags="&lt;aircraft-performance&gt;&lt;instrument-flight-rules&gt;&lt;altitude&gt;&lt;climb&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25159" PostTypeId="2" ParentId="25158" CreationDate="2016-02-12T11:18:30.077" Score="14" Body="&lt;p&gt;Because ATC expects you to climb with at least 500 fpm when crossing to the next level. Otherwise you will block intermediate levels for an extended period of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are climbing 2000ft to the next available level for your direction of travel, that will take at most 4 minutes at 500fpm or more. This means the flight level you are crossing will need to be free of traffic from the opposite direction for four minutes to ensure legal separation is maintained. If you climb slower, ATC can't properly accomodate your climb. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2016-02-12T11:18:30.077" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25161" PostTypeId="2" ParentId="25142" CreationDate="2016-02-12T14:07:32.207" Score="10" Body="&lt;p&gt;In most aircraft, the standby magnetic compass is mounted well above the main instrument panel, usually above the central window post, in order to reduce interference. In the three piece window of the MD-80 (without a central window post), this is not possible, resulting in the different location for compass.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;All the Douglas jet aircraft has this type of mounting. According to &lt;a href=&quot;https://groups.yahoo.com/neo/groups/DC8/conversations/topics/413&quot;&gt;this thread&lt;/a&gt;, the compass was first mounted on the instrument panel, which resulted in severe interference, resulting in its relocation. From the thread:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I understood that, early in the 60's, the compass was relocated in all DC-8 production due the three section type of the windshield (the compass has a lot of error/deviation at the center of the glareshield panel).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note: I'm not able to find original documents supporting this. All the documents I can get simply instruct to check the compass using mirrors in the glare shield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This design decision was used in all the later Douglas models, DC-9, MD-80/90 right upto Boeing 717 (which was developed as Dc-95); incidentally, all these models used a three piece front windshield devoid of center post.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-12T14:07:32.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25162" PostTypeId="1" AcceptedAnswerId="38800" CreationDate="2016-02-12T14:31:15.510" Score="14" ViewCount="45360" Body="&lt;p&gt;Pax in commercial transport is used as something like &lt;em&gt;persons&lt;/em&gt; or &lt;em&gt;passengers&lt;/em&gt;, in the context of counting people, e.g. 150 pax onboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dHAcD.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dHAcD.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.amadeus.com/web/amadeus/en_1A-corporate/Airlines/Airline-Systems/Airline-Core-Systems/Alt%C3%A9a-Suite/Ticketing/1400000041543-Categorizable_P-AMAD_CategoryDetailPpal-1319637765587?industrySegment=1259068355670&quot; rel=&quot;noreferrer&quot;&gt;Amadeus&lt;/a&gt; capture, &lt;a href=&quot;http://www.alp.co.il/faq/?product=Vista&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I observed that in German writers tend to use the meaning:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;PAX = &lt;em&gt;Persons approximately&lt;/em&gt;.&lt;br&gt;&#xA;  &lt;sup&gt;(Source: &lt;a href=&quot;http://cor.europa.eu/en/documentation/studies/Documents/2014-mobility-geographically-demographically-challenged-regions/2014-Mobility-Geographically-Demographically-Challenged-Regions.pdf&quot; rel=&quot;noreferrer&quot;&gt;European Union and the Committee of the Regions&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://english.stackexchange.com/questions/24951/what-does-pax-mean-in-the-context-of-the-apartment-rental&quot;&gt;English.SE&lt;/a&gt; has a page for &lt;em&gt;What does “pax” mean in the context of the apartment rental?&lt;/em&gt; &lt;a href=&quot;https://english.stackexchange.com/questions/24951/what-does-pax-mean-in-the-context-of-the-apartment-rental#answer-25130&quot;&gt;Selected&lt;/a&gt; answer:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pax isn't exactly shorthand for Passengers. It's short for&#xA;  &lt;em&gt;Passengers and Passes&lt;/em&gt;.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But the author of the answer agreed that &lt;a href=&quot;https://english.stackexchange.com/questions/24951/what-does-pax-mean-in-the-context-of-the-apartment-rental#answer-25166&quot;&gt;another answer&lt;/a&gt; was likely more accurate. The latter has a reference to a magazine, &lt;em&gt;&lt;a href=&quot;http://books.google.com/books?ei=rbfMTa3gCILJgQfemqnbBA&amp;amp;ct=result&amp;amp;id=mEQPAAAAIAAJ&amp;amp;dq=%22pax%22%20%2Bcargo%20-con&amp;amp;q=1946#search_anchor&quot; rel=&quot;noreferrer&quot;&gt;Air Facts: The Magazine for Pilots - 1946&lt;/a&gt;&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cargo is known as &quot;cargo&quot;, but &lt;em&gt;passengers&lt;/em&gt; are called &quot;pax&quot; by the&#xA;  traffic department, who puts them on and takes them off the airplane&#xA;  and &quot;bodies&quot; by the crews who fly them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pax could be from &lt;em&gt;passenger&lt;/em&gt; as usually assumed in the Aviation community, albeit I don't see why not *pass&quot; instead. I wouldn't be surprised it comes from the merchant navy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can we track the use further back to the origin in aviation field?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="14957" LastEditDate="2017-06-09T15:13:03.557" LastActivityDate="2021-03-21T16:23:09.760" Title="What is the origin of the term &quot;pax&quot;?" Tags="&lt;aviation-history&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25163" PostTypeId="1" AcceptedAnswerId="25165" CreationDate="2016-02-12T15:13:39.957" Score="10" ViewCount="2909" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/9945/does-a-multi-engine-rating-propagate-down-from-commercial-to-private?rq=1&quot;&gt;this answer&lt;/a&gt;, privileges of single-engine and multi-engine are separated. A pilot who obtained his PPL on a single-engine and his CPL on a multi-engine is not permitted to exercise his commercial privilege on a single-engine airplane. To do so, he must past another CPL exam on a single-engine plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this do? I see no reason why a pilot who can operate a multi-engine airplane safely is incapable of doing the same in a single-engine. Training in a multi-engine would include an all-engine-failure scenario, which would be similar in single-engine.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-02-12T17:28:26.147" Title="Why do multi-engine privileges not propagate down to single-engine?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25164" PostTypeId="2" ParentId="25150" CreationDate="2016-02-12T15:30:32.410" Score="9" Body="&lt;p&gt;For altitude callouts during the landing phase (2500, 1000, 500, 400, ... 100, 50, 20, 10), the computer simply reads the data from the radar altimeter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radar altimeter uses radio waves to measure the vertical distance between the airplane and any ground / obstacle below. The radio altimeter is mounted on the underside of the fuselage. They are usually accurate up to feet. This is different than the standard altimeter in the cockpit, which measure air pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radio altimeter has no idea where the runway is; if there is uneven terrain leading to the airport, or if the pilots' descend profile does not match the glideslope, the readings (and thus the callouts) will not reflect the height above runway elevation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the airlines can customize the altitude callouts. Different manufacturers also uses slightly different callout patterns.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The second type of audio alerts are messages from a &lt;a href=&quot;https://en.wikipedia.org/wiki/Terrain_awareness_and_warning_system&quot;&gt;Terrain Awareness and Warning System&lt;/a&gt; (TAWS). These systems uses radio altimeter, and may combine information from other sources, such as GPS and a global terrain database, to issue alert messages to the pilots if terrain impact is imminent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the radio altimeter is only capable of detecting ground directly below, it is unable to provide timely warnings in certain situations, e.g. approaching a steep hill. By integrating with GPS data and a terrain database, the computers can predict the flight path of the aircraft and issue warnings if a risk of collision exists.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-12T19:07:06.213" LastActivityDate="2016-02-12T19:07:06.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25165" PostTypeId="2" ParentId="25163" CreationDate="2016-02-12T15:44:19.207" Score="12" Body="&lt;p&gt;Just like having a SEL Commercial with a MEL PPL doesn't mean you can operate a MEL commercially. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The certification requirements require the demonstration of particular maneuvers like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Chandelle&quot;&gt;Chandelle&lt;/a&gt; which includes a slow-flight phase. Slow flight on a single is significantly different than slow flight on an MEL because of p-factor and aircraft handling. Same thing with lazy-8's &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another reason is engine-outs. Engine outs have to be demonstrated, and on a Multi, an engine out means you can limp it to your closest airfield. On a single, unless you are in gliding distance, you will be putting it down off-field. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA also has different &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/faa-s-8081-12c.pdf&quot;&gt;test standards&lt;/a&gt; for SEL commercial versus MEL commercial. Because you've demonstrated satisfaction on an MEL doesn't mean you are proficient in SEL operations for the same maneuvers, so the FAA makes you demonstrate it.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-02-12T15:44:19.207" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25167" PostTypeId="1" CreationDate="2016-02-12T16:59:43.830" Score="1" ViewCount="124" Body="&lt;p&gt;At night, some jet aircraft like Mirage 2000 leave a trail of discs behind in their jet, these are also known as &lt;a href=&quot;https://en.wikipedia.org/wiki/Shock_diamond&quot; rel=&quot;nofollow&quot;&gt;Mach rings&lt;/a&gt; or Mach diamonds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How are they formed and what atmospheric conditions govern their formation?&lt;/p&gt;&#xA;" OwnerUserId="13454" LastEditorUserId="3201" LastEditDate="2016-02-13T02:16:58.353" LastActivityDate="2016-02-13T02:16:58.353" Title="Reason behind formation of Mach rings" Tags="&lt;jet-engine&gt;&lt;supersonic&gt;&lt;shock-waves&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-02-12T17:25:14.707" ContentLicense="CC BY-SA 3.0" />
  <row Id="25169" PostTypeId="1" AcceptedAnswerId="25212" CreationDate="2016-02-12T17:25:00.297" Score="24" ViewCount="41582" Body="&lt;ul&gt;&#xA;&lt;li&gt;What is a TRACON or Terminal Control?&lt;/li&gt;&#xA;&lt;li&gt;When do pilots need to be helped by a TRACON?&lt;/li&gt;&#xA;&lt;li&gt;Where is it usually located and what is the difference between TRACON, En Route and Tower?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="14957" LastEditDate="2020-09-18T11:32:02.517" LastActivityDate="2021-02-10T12:08:34.727" Title="What is a TRACON?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;&lt;faa&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25172" PostTypeId="1" CreationDate="2016-02-12T18:25:18.930" Score="8" ViewCount="1669" Body="&lt;p&gt;The value of a commonly understood &lt;a href=&quot;https://en.wikipedia.org/wiki/Airfield_traffic_pattern#Altitudes&quot;&gt;traffic pattern altitude&lt;/a&gt; is obvious, but what is the history behind TPA of eight hundred feet in particular? Why not 700 or 900?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was the later move to 1,000 AGL because of easy math only, or were there other reasons?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2016-04-09T00:27:46.177" Title="What made 800 feet and later 1,000 feet attractive as the standard traffic pattern altitude?" Tags="&lt;aviation-history&gt;&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25173" PostTypeId="1" AcceptedAnswerId="25174" CreationDate="2016-02-12T21:38:38.170" Score="4" ViewCount="942" Body="&lt;p&gt;So we fly a 1973 Piper Archer, with shoulder harnesses installed from the factory. The question is: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would the shoulder harness becoming INOP (jamming &amp;amp; not coming loose) ground this airplane or could you fly without it, since the FAA required shoulder harnesses as of 1978 (or some other year...?)?&lt;/p&gt;&#xA;" OwnerUserId="13281" LastActivityDate="2016-02-13T18:41:23.130" Title="If a shoulder harness becomes INOP in an aircraft certified before 1978, is it still required equipment?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;equipment&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25174" PostTypeId="2" ParentId="25173" CreationDate="2016-02-12T22:55:32.613" Score="6" Body="&lt;p&gt;Shoulder harnesses have been required for all aircraft manufactured since &lt;a href=&quot;https://www.faa.gov/aircraft/gen_av/harness_kits/media/shoulderpolicy.pdf&quot; rel=&quot;noreferrer&quot;&gt;December 12, 1986 for all seats, July 19, 1978 for front seats&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;14 CFR 91.107 (2) and (3) is pretty clear:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) No pilot may cause to be moved on the surface, take off, or land a U.S.-registered civil aircraft (except a free balloon that incorporates a basket or gondola, or an airship type certificated before November 2, 1987) unless the pilot in command of that aircraft ensures that each person on board has been notified to fasten his or her safety belt &lt;strong&gt;and, if installed, his or her shoulder harness&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;(3) Except as provided in this paragraph, each person on board a U.S.-registered civil aircraft (except a free balloon that incorporates a basket or gondola or an airship type certificated before November 2, 1987) must occupy an approved seat or berth with a safety belt &lt;strong&gt;and, if installed, shoulder harness&lt;/strong&gt;, properly secured about him or her during movement on the surface, takeoff, and landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So what I read above can be interpreted as &amp;quot;if it's installed, it's required&amp;quot;.&lt;/p&gt;&#xA;&lt;p&gt;Some aircraft required an STC to retrofit the belts, you'll need to find out if that is the case (if it is, you can't remove it, but if there is no STC it could possibly be removed, a call to your local FSDO can clear that up). However I've been told that if the aircraft is equipped with shoulder harnesses, then they are required to be used.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-02-12T23:00:39.807" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25175" PostTypeId="1" AcceptedAnswerId="25177" CreationDate="2016-02-12T23:30:15.343" Score="5" ViewCount="7039" Body="&lt;p&gt;What visibility and cloud clearances are required for airplanes conducting visual approaches during IFR while flying under FAA regulations? Is the visual approach a purely VFR maneuver requiring the usual VFR weather minimums for the airspace being flown? Or does the visual approach maneuver flown under IFR supersede normal VFR weather minimums?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2016-02-13T17:45:15.793" Title="What visibility and cloud clearances are required for airplanes conducting visual approaches?" Tags="&lt;instrument-flight-rules&gt;&lt;ifr-navigation&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25177" PostTypeId="2" ParentId="25175" CreationDate="2016-02-13T01:29:33.193" Score="5" Body="&lt;p&gt;This depends:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Under part 91, you just have to remain clear of clouds and have a minimum of a 1,000 ft. ceiling and 3 SM visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial operations (121 and 135) are further restricted by their Operations Specifications and have to maintain VFR weather minimums appropriate for the airspace that they are in (among other things, see below).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an excerpt from the AIM (there is more details there for different operations, with the differences between controlled and uncontrolled fields, etc.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;5−4−23(a). Visual Approach&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; A visual approach is conducted on an IFR flight plan and authorizes a pilot to proceed visually and clear of clouds to the&#xA;  airport. The pilot must have either the airport or the preceding&#xA;  identified aircraft in sight. This approach must be authorized and&#xA;  controlled by the appropriate air traffic control facility. Reported&#xA;  weather at the airport must have a ceiling at or above 1,000 feet and&#xA;  visibility 3 miles or greater. ATC may authorize this type approach&#xA;  when it will be operationally beneficial. Visual approaches are an IFR&#xA;  procedure conducted under IFR in visual meteorological conditions.&#xA;  Cloud clearance requirements of 14 CFR Section 91.155 are not&#xA;  applicable, unless required by operation specification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Part 135 Ops Spec for this contains the following requirements for a visual approach:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;b. Terminal arrival IFR - Visual approach or a Charted Visual Flight&#xA;  Procedure (CVFP).&lt;/strong&gt;&lt;br&gt;&#xA;  The flightcrew may accept a visual approach or a&#xA;  CVFP provided all the following conditions exist. The flightcrew may&#xA;  not accept a visual approach or a CVFP unless the limitations and&#xA;  provisions of subparagraph f. of this operations specification are&#xA;  met. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The flight is operated and remains in Class B, C, or D&#xA;  airspace, within 35 miles of the destination airport in Class E&#xA;  airspace, or the airspace beneath the designated transition area. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2)&#xA;  The flight is under the control of an Air Traffic Control (ATC)&#xA;  facility. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The flightcrew must maintain the basic cloud clearance&#xA;  as specified in Section 91.155. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) For a visual approach without a&#xA;  CVFP - The flightcrew must be able to establish and maintain visual&#xA;  contact with the airport or maintain visual contact with the traffic&#xA;  to be followed as directed by ATC. In addition, the following&#xA;  provisions and weather conditions at the airport during the approach&#xA;  must be met: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Reported visibility must be as specified in Section&#xA;  91.155, but not lower than a visibility of three miles and reported ceiling must be 1,000 feet or greater, or  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) When in the terminal&#xA;  area with the reported visibility not lower than three miles and&#xA;  ceiling not reported, the flightcrew may continue to a landing if the&#xA;  runway of intended landing is in sight and the flightcrew can maintain&#xA;  visual contact with the runway throughout the approach and landing,&#xA;  and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Ceiling and cloud clearance must be as such to allow the&#xA;  flightcrew to maintain the minimum altitudes prescribed in Section&#xA;  91.129, 91.130, or 91.131, as applicable for the airspace class in which the flight is operated. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(5) For a CVFP - The flightcrew must be&#xA;  able to establish and maintain visual contact with the airport or the&#xA;  charted visual landmark(s) for the CVFP throughout the approach and&#xA;  landing. In addition, the weather conditions at the airport at the&#xA;  time of the approach must be reported to be at or above the weather&#xA;  minima established for the CVFP, but never lower than the VFR landing&#xA;  weather minima stated in Section 135.205 in uncontrolled airspace.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;f. Special Limitations and Provisions for Visual Flight Rules.&lt;/strong&gt; All VFR operations authorized by this operations specification shall be&#xA;  conducted in accordance with the following limitations and provisions.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The certificate holder must identify obstacles and use airport&#xA;  obstacle data which ensures that the performance requirements of Part&#xA;  135 are met.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The weather conditions must allow the flightcrew sufficient&#xA;  visibility to identify and avoid obstacles and safely maneuver using&#xA;  external visual references and to maintain minimum altitudes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-02-13T05:19:53.987" LastActivityDate="2016-02-13T05:19:53.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25178" PostTypeId="1" AcceptedAnswerId="25188" CreationDate="2016-02-13T01:40:51.047" Score="10" ViewCount="2105" Body="&lt;p&gt;The MD-80 family has a 2-3 seat layout as seen in this image:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NkoM4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LJsXd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the layout have any influence on the balance of the aircraft and if so what is used to balance out the weight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.seatguru.com/airlines/Allegiant_Air/Allegiant_Air_MD-80.php&quot; rel=&quot;noreferrer&quot;&gt;seatguru.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="14897" LastEditDate="2016-09-06T22:15:32.997" LastActivityDate="2016-10-21T05:14:07.330" Title="Does the MD-80 seat layout affect the balance of the aircraft?" Tags="&lt;weight-and-balance&gt;&lt;md-80&gt;&lt;dc-9-family&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25179" PostTypeId="2" ParentId="25173" CreationDate="2016-02-13T02:48:41.140" Score="2" Body="&lt;p&gt;You're good to go... most likely:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are decisions based on FAR 91.213 (d) that would have to be answered first but if you run down those, odds are favorable that you will find that you can legally de-activate or remove the shoulder harness in an airworthy manner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be considered airworthy your aircraft must meet its FAA approved type design or be in a properly altered state. That means everything installed must work or be altered &quot;properly&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how would you &quot;properly&quot; alter your Piper with the shoulder harness issue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR 91.213 (d) allows you to fly with inoperative instruments or equipment. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) Except for operations conducted in accordance with paragraph (a)&#xA;  or (c) of this section, a person may takeoff an aircraft in operations&#xA;  conducted under this part with inoperative instruments and equipment&#xA;  without an approved Minimum Equipment List provided—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The flight operation is conducted in a—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Rotorcraft, non-turbine-powered airplane, glider, lighter-than-air&#xA;  aircraft, powered parachute, or weight-shift-control aircraft, for&#xA;  which a master minimum equipment list has not been developed; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Small rotorcraft, nonturbine-powered small airplane, glider, or&#xA;  lighter-than-air aircraft for which a Master Minimum Equipment List&#xA;  has been developed; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;OK, your piper clears #1.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) The inoperative instruments and equipment are not—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Part of the VFR-day type certification instruments and equipment&#xA;  prescribed in the applicable airworthiness regulations under which the&#xA;  aircraft was type certificated;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Your Piper was certificated under CAR3... just try to find anything about shoulder harnesses there...  So far so good...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(ii) Indicated as required on the aircraft's equipment list, or on the&#xA;  Kinds of Operations Equipment List for the kind of flight operation&#xA;  being conducted;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Read through your AFM or POH to see if it requires it. Maybe it does but I doubt it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iii) Required by §91.205 or any other rule of this part for the&#xA;  specific kind of flight operation being conducted; or&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;91.205 requires lap belt only (metal type) but does not mention shoulder harness. I'm assuming the shoulder harness is not an integral part of the lap belt. This is key... you need a lap belt.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(iv) Required to be operational by an airworthiness directive; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Been doing this my whole career and I'm not aware of an AD about it that is applicable to your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(3) The inoperative instruments and equipment are—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Removed from the aircraft, the cockpit control placarded, and the&#xA;  maintenance recorded in accordance with §43.9 of this chapter; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Deactivated and placarded “Inoperative.” If deactivation of the&#xA;  inoperative instrument or equipment involves maintenance, it must be&#xA;  accomplished and recorded in accordance with part 43 of this chapter;&#xA;  and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ok, you need to have an A&amp;amp;P remove or deactivate it, write a maintenance entry about removing it and placard it as &quot;inop&quot; if necessary.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(4) A determination is made by a pilot, who is certificated and&#xA;  appropriately rated under part 61 of this chapter, or by a person, who&#xA;  is certificated and appropriately rated to perform maintenance on the&#xA;  aircraft, that the inoperative instrument or equipment does not&#xA;  constitute a hazard to the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Well, it could constitute a risk to the occupant I suppose, but not a hazard to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft with inoperative instruments or equipment as provided in&#xA;  paragraph (d) of this section is considered to be in a properly&#xA;  altered condition acceptable to the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's how you properly alter your shoulder harness issue to a manner acceptable to the FAA... &lt;/p&gt;&#xA;" OwnerUserId="340" LastEditorUserId="8490" LastEditDate="2016-02-13T18:41:23.130" LastActivityDate="2016-02-13T18:41:23.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25180" PostTypeId="2" ParentId="23157" CreationDate="2016-02-13T02:58:46.507" Score="0" Body="&lt;p&gt;No, it is a 3 stage process.  The concept would be to convert the seat chassis itself into some type of guided flying platform like a rocket jet suit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) The ejection process and auto parachute deploy would be the same as now. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) Next after deployment the pilot while parachuting down has an option to just parachute down. OR if over hostile territory to further deploy a jet pack that separated from the seat and chute, and the pilot could fly away some distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) There would be a secondary parachute that could be deployed miles away after flying the seat (jetpack). &lt;/p&gt;&#xA;" OwnerUserId="13479" LastEditorUserId="12220" LastEditDate="2016-02-13T03:09:04.733" LastActivityDate="2016-02-13T03:09:04.733" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25181" PostTypeId="2" ParentId="17030" CreationDate="2016-02-13T03:19:05.227" Score="9" Body="&lt;p&gt;Traditional anti-ice systems use engine bleed air through the pneumatic system. Engine bleed air is air that is compressed by the engine compressor to high pressure. Due to thermodynamic effects the air also warms to fairly high temperatures. This air is then bled off the engine through valves to supply the aircraft's pneumatic system. The pneumatic air is then sprayed on the inside of the leading edge of the wing or engine cowl to prevent ice accumulation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine bled is a very expensive source of energy on an aircraft because compressing air isn't that efficient, the engine core has to be slightly larger to accommodate the increased airflow, and the pneumatic system itself is typically one of the least reliable systems on the aircraft. The system also uses many large ducts that are heavy and take up a lot of space, which dictates larger passages in structure, which is more weight again. However, bleed air is available making it an attractive source of energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787, however, shed the vast majority of the pneumatic system (see the link Sports Racer posted above &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_3.html&quot;&gt;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_3.html&lt;/a&gt;). This decreases the specific fuel consumption of the engines quite a bit. Reduces weight, and removes an very unreliable system from the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 787 is able to get away with this because it has very advanced electrical starter/generators. The generators can produce about 500 KW each, significantly more than any other Boeing aircraft. Since there is so much power available, electronic heater blankets for anti-ice are feasible, no other Boeing aircraft has the excess power to use electric anti-ice on the wings. Besides being much lighter, the electric blankets will use the energy more efficiently as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although the generators still pull power off the engines, increasing fuel burn, the process is much more efficient than using bleed air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FYI: The generators are also the engine starters, which eliminates another major pneumatic component on other aircraft.  &lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-02-13T03:19:05.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25182" PostTypeId="2" ParentId="25178" CreationDate="2016-02-13T03:34:30.073" Score="9" Body="&lt;p&gt;The &quot;D&quot; seat is very near the aircraft centerline, and thus the roll axis. Since roll moment is the distance from the roll axis times weight, if the distance is small, the roll moment is very small. What roll moment is created can easily be canceled by a little bit of aileron trim if needed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The water tank on MD-80s is also placed on the LH side of the cargo. Full this is about 350 lbs, further from the centerline than the &quot;D&quot; seats. Also the LH side has an extra service door in the aft and the front LH door is larger than the R1 door, although the RH side also has the cargo doors. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2016-10-21T05:14:07.330" LastActivityDate="2016-10-21T05:14:07.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25184" PostTypeId="2" ParentId="23543" CreationDate="2016-02-13T13:25:34.903" Score="-5" Body="&lt;p&gt;The A320 has a yellow hydraulic system pressure indication on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Electronic_centralised_aircraft_monitor&quot; rel=&quot;nofollow&quot;&gt;ECAM&lt;/a&gt; which shows xx =even the press by edp or by yellow elect pump = the press txd replaced -the power to txd measured ok 28 v=xx indication on yellow sys is always with press applied or without.&lt;/p&gt;&#xA;" OwnerUserId="13483" LastEditorUserId="12720" LastEditDate="2016-02-13T14:19:34.080" LastActivityDate="2016-02-13T14:19:34.080" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25185" PostTypeId="1" AcceptedAnswerId="25186" CreationDate="2016-02-13T13:33:11.437" Score="3" ViewCount="245" Body="&lt;p&gt;After taking a new plane from the manufacturer's factory to its airport base, the plane must undergo a Certification Flight before starting to operate with the airline:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is a certification flight?&lt;/li&gt;&#xA;&lt;li&gt;What is the purpose of it?&lt;/li&gt;&#xA;&lt;li&gt;What are the tasks done on a Certification Flight?&lt;/li&gt;&#xA;&lt;li&gt;Why doing a Certification Flight if the aircraft has already been tested before?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-13T13:42:13.540" LastActivityDate="2016-02-13T14:18:57.863" Title="What is a Certification Flight?" Tags="&lt;faa-regulations&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25186" PostTypeId="2" ParentId="25185" CreationDate="2016-02-13T14:07:44.843" Score="3" Body="&lt;p&gt;I believe what you are referring to is an &lt;em&gt;acceptance flight&lt;/em&gt;, rather than a &lt;em&gt;certification flight&lt;/em&gt;. Certification flights (usually there many) are flights which the manufacturer demonstrates to aviation authorities that a new &lt;em&gt;design&lt;/em&gt; of an aircraft is safe. However, just because a design has been tested, does not mean a new aircraft is produced exactly to the design. Acceptance flight is a test flight which make sure the aircraft has been manufactured &lt;em&gt;up to standard&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Acceptance flights are also required after major maintenance work or avionics upgrades. Its purpose is to explore the entire flight envelope and ensure emergency / backup systems work as expected. During a normal flight, only a portion of the systems' functions are used. A test flight is a complete evaluation of all conditions, such that malfunctions or deviations will not go unnoticed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, the pilots will first examine critical systems (e.g. engines, flight controls) on the ground. Depending on the aircraft, the tests to be completed in the air include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine shutdown and restarts&lt;/li&gt;&#xA;&lt;li&gt;autopilot roll rates, flap extension speed, engine response etc.&lt;/li&gt;&#xA;&lt;li&gt;Alternate gear extension&lt;/li&gt;&#xA;&lt;li&gt;Fuel jettison&lt;/li&gt;&#xA;&lt;li&gt;Over-speed warnings&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/XL_Airways_Germany_Flight_888T&quot; rel=&quot;nofollow&quot;&gt;Stall protection systems&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Ground Proximity Warning System (GPWS)&lt;/li&gt;&#xA;&lt;li&gt;Auxiliary Power Unit (APU) operation at high altitude&lt;/li&gt;&#xA;&lt;li&gt;Cabin service systems&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-13T14:18:57.863" LastActivityDate="2016-02-13T14:18:57.863" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25187" PostTypeId="1" AcceptedAnswerId="25200" CreationDate="2016-02-13T14:59:41.493" Score="4" ViewCount="1041" Body="&lt;p&gt;I would like to know how laminar/turbulent flow affects engine performance. Any additional thoughts on the topic, even if not strictly related to the main question, are welcomed.&lt;/p&gt;&#xA;" OwnerUserId="13402" LastActivityDate="2016-02-14T10:19:41.100" Title="What type of flow is preferable for jet engines?" Tags="&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;inlet&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25188" PostTypeId="2" ParentId="25178" CreationDate="2016-02-13T15:56:07.947" Score="9" Body="&lt;p&gt;Based on this diagram—found in &lt;a href=&quot;http://Based%20on%20this%20diagram%20found%20in%20this%20Boeing%20MD-80%20series%20document&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Boeing MD-80 series document&lt;/a&gt;—we can estimate the average lateral center of gravity along the &lt;a href=&quot;https://aviation.stackexchange.com/a/3867/12720&quot;&gt;buttock line&lt;/a&gt; for each passenger seat:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2GuZU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2GuZU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the seating diagram that you provided in your question, I estimated the average center of weight along the buttock line for &lt;code&gt;A&lt;/code&gt;, &lt;code&gt;C&lt;/code&gt;, &lt;code&gt;D&lt;/code&gt;, &lt;code&gt;E&lt;/code&gt;, and &lt;code&gt;F&lt;/code&gt; to be &lt;code&gt;-50&lt;/code&gt;, &lt;code&gt;-30&lt;/code&gt;, &lt;code&gt;+10&lt;/code&gt;, &lt;code&gt;+31&lt;/code&gt;, and &lt;code&gt;+51&lt;/code&gt; respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can use the following formula to calculate the lateral CG for the full load of passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$A_w$ is the sum of all weights for passengers in &lt;code&gt;A&lt;/code&gt; seats (and so also for &lt;code&gt;C&lt;/code&gt;, etc)&lt;/li&gt;&#xA;&lt;li&gt;$A_a$ is the lateral moment arm location along the buttock line for passengers in &lt;code&gt;A&lt;/code&gt; seats (and so also for &lt;code&gt;C&lt;/code&gt;, etc)&lt;/li&gt;&#xA;&lt;li&gt;$C_G$ is the solution to the lateral center of gravity for all seat loads.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;C_G=\frac{(A_w\cdot A_a)+(C_w\cdot C_a)+(D_w\cdot D_a)+(E_w\cdot E_a)+(F_w\cdot F_a)}{A_w+C_w+D_w+E_w+F_w}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume that every seat depicted in the question diagram is occupied by a 170 lb person, the solution $C_G$ is $3.4$—that is, 3.4 inches right of the center of the cabin, under the left side of seat &lt;code&gt;D&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;3.4 inches is very little variation in lateral CG, especially for so large an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other load considerations notwithstanding, I don't think the assymetrical seating arrangement is cause for concern.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-10-12T15:34:51.487" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25190" PostTypeId="2" ParentId="25145" CreationDate="2016-02-13T16:45:39.550" Score="6" Body="&lt;p&gt;First of all, you must determine if the gear is broken or the lights are broken. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you've determined that the lights are in working order, then you can trouble shoot the gear itself using the checklist in the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you've gone through the checklist in the plane, and you still don't have indication that the gear is down and locked, then there are many techniques that go beyond what's in the POH that rely on knowing how the gear works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft, the gear falls naturally using gravity, and is held down by a mechanical latch. If the gear fails to latch, then it is possible to slip the aircraft in the direction of the wheel that is not down. This will put the sideways slipstream on the gear, and could help to push it into the locked position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the nosewheel unfolds in the forward direction, it may be that slowing the plane to MCA can allow the nose gear to come forward and lock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are just a couple of examples, but knowing exactly how the gear works in your airplane will help you at a crucial time.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-02-13T16:45:39.550" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25192" PostTypeId="2" ParentId="25175" CreationDate="2016-02-13T17:00:54.913" Score="-1" Body="&lt;p&gt;&lt;code&gt;What visibility and cloud clearances are required?&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VFR, as per 91.129, 91.130, or 91.131 for the various classes of airspace&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-02-13T17:45:15.793" LastActivityDate="2016-02-13T17:45:15.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25193" PostTypeId="1" CreationDate="2016-02-13T18:15:29.500" Score="1" ViewCount="532" Body="&lt;p&gt;What happens if an object (plane or space ship) travels at a speed less than that of earth rotation?&lt;/p&gt;&#xA;" OwnerUserId="13488" LastEditorUserId="12220" LastEditDate="2016-02-13T18:20:47.357" LastActivityDate="2016-02-13T20:34:37.947" Title="What is the effect of earth's speed on flight?" Tags="&lt;airspeed&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-02-13T19:24:30.797" ContentLicense="CC BY-SA 3.0" />
  <row Id="25196" PostTypeId="1" AcceptedAnswerId="25296" CreationDate="2016-02-13T18:48:05.950" Score="8" ViewCount="2674" Body="&lt;p&gt;Light general aviation piston twins have full-feathering props. It's normal to perform feathering checks by pulling the prop level all the way down to feather, briefly, and observing the changes. First, why is the feather check performed and what is the pilot looking for during this check? Also, how far should the RPMs be allowed to drop? Could allowing a large RPM drop cause mechanical damage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that the specific allowances may vary between Lycoming and Continental engines and between models, but an average number would be helpful for the sake of the question.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2018-01-03T16:47:48.930" Title="Why is a feather check performed on a piston engine and how much RPM drop should be allowed?" Tags="&lt;piston-engine&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25197" PostTypeId="2" ParentId="25193" CreationDate="2016-02-13T18:58:58.670" Score="2" Body="&lt;p&gt;The stationary plane and the atmosphere were already moving at the speed of Earth's rotation. Because of this, the Earth's rotational speed really has very little effect on aircraft speed. To answer the second part of your question, almost all passenger jets fly slower than the Earth's rotation. The Earth rotates at 1675 km/hr at the equator; average cruise speed is 878-926 km/hr.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="13371" LastEditDate="2016-02-13T20:34:37.947" LastActivityDate="2016-02-13T20:34:37.947" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25198" PostTypeId="1" AcceptedAnswerId="25202" CreationDate="2016-02-13T20:55:52.740" Score="5" ViewCount="2680" Body="&lt;p&gt;Both of them prevent the aircraft from stalling, so is there any difference between them? The wing fence doesn't produce a vortex, so how does it work?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-08-29T01:57:20.910" LastActivityDate="2019-08-29T01:57:20.910" Title="What is the difference between a stall fence and a vortex generator?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;vortex-generators&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25199" PostTypeId="2" ParentId="11318" CreationDate="2016-02-13T21:09:15.897" Score="9" Body="&lt;p&gt;First, As a frequent flyer from Omaha, NE to Rochester, NY via O'Hare, I have been in the &quot;Penalty box&quot; more times than can be counted on hands and toes. A penalty box is simply a holding ramp for planes that currently have no place to be on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the use of the penalty box has increased since all airlines pad their inflight times with extra time. The reason is simple, it makes them look better when you always arrive early -or- on time if problems are encountered. (expectations are set low, then exceeded.) Early arrivals caused by padded transit times are more likely to wind up waiting for a gate in the penalty box. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, this is an old layout of O'Hare; if you notice, the current United concourses are not present. Date here is 1981. This is approximately when construction on them was commenced. Furthermore, more runways have been built since.  This may be a copy of the airport before modern expansions were begun.  The current &quot;penalty box&quot; has moved to where the &quot;Pe&quot; is in the word Penalty box above.&lt;/p&gt;&#xA;" OwnerUserId="13492" LastEditorUserId="12720" LastEditDate="2016-02-13T21:58:51.737" LastActivityDate="2016-02-13T21:58:51.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25200" PostTypeId="2" ParentId="25187" CreationDate="2016-02-13T21:13:32.250" Score="2" Body="&lt;p&gt;The noise within the engine will make all flow turbulent. There is not much liberty for the engine designer to choose the type of boundary layer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, a laminar boundary layer is preferable as long as the flow is accelerated, because viscous drag will be lower, and a turbulent one is better when it is decelerated, so &lt;a href=&quot;https://aviation.stackexchange.com/questions/24752/is-a-golf-ball-surface-a-good-idea-for-wings-or-fuselage/24759?s=2%7C0.2216#24759&quot;&gt;separation can be delayed&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of boundary layer phenomena, turbulence is helpful for keeping the &lt;a href=&quot;https://aviation.stackexchange.com/questions/11949/how-is-combustion-flame-maintained-in-the-combustion-chamber-after-igniters-are/11964?s=1%7C0.1027#11964&quot;&gt;combustion process&lt;/a&gt; going in the combustor and especially in the afterburner. Ahead of the combustor all engines have a diffusor to &lt;a href=&quot;https://aviation.stackexchange.com/questions/11744/why-do-gases-in-the-combustion-chamber-only-flow-one-direction-to-the-gas-turbin/11752#11752&quot;&gt;slow down the compressed air&lt;/a&gt;, so it has time to mix with the fuel and burn as much of it as possible. Note that the diffusor only slows down the axial movement of the air, so radial velocities will not be affected and be relatively larger relative to the axial flow at the entry of the combustion chamber. This makes the flow more turbulent, which is helpful for better fuel-air mixing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the afterburner, flame holders are needed to produce pockets of slow-moving, hot gas which can ignite the fuel-air mixture. Again, they cause more turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lkyDO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lkyDO.png&quot; alt=&quot;Flame holder&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flame holder (10) with annular selectors (9) of an afterburner (picture &lt;a href=&quot;http://patentimages.storage.googleapis.com/US20090260366A1/US20090260366A1-20091022-D00000.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the nozzle, turbulent mixing of the hot core flow and the bypass flow reduces noise. Engine nozzles use a &lt;a href=&quot;https://aviation.stackexchange.com/questions/12832/why-does-the-boeing-787-engine-nacelle-exhaust-have-such-an-unusual-shape/12834?s=2%7C0.1085#12834&quot;&gt;variety of means&lt;/a&gt; to speed up the mixing process.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-14T10:19:41.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25202" PostTypeId="2" ParentId="25198" CreationDate="2016-02-14T00:06:20.550" Score="7" Body="&lt;p&gt;The wing fence is more or less what it is called- a fence. For swept wing aircraft, the local flow is not along the direction of flight, as there is a significant spanwise flow from the center towards the tips. It can be seen in the following figure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WbLmD.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WbLmD.gif&quot; alt=&quot;Spanwise flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://fuckyeahfluiddynamics.tumblr.com/post/16984040595/flow-over-a-swept-wing-behaves-very-differently&quot; rel=&quot;noreferrer&quot;&gt;fuckyeahfluiddynamics.tumblr.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The end result is that the boundary layer continues to grow (thicken) in this direction, with outboard regions more prone to stall than inboard ones. Basically, the wing fences stop the spanwise flow, with the result being a new (thinner) boundary layer starts on the other side of the fence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of a vortex generator, the VGs basically create a vortex which re-invigorates the boundary layer by mixing free stream air with that of the boundary layer, thereby preventing separation. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-14T00:06:20.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25203" PostTypeId="1" AcceptedAnswerId="25204" CreationDate="2016-02-14T04:32:30.140" Score="11" ViewCount="2901" Body="&lt;p&gt;I'm having trouble identifying a jet and am hoping someone can provide some help.  Here is the best picture I've been able to capture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mWfha.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mWfha.jpg&quot; alt=&quot;clearest&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The closest similar jet I've been able to find is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Douglas_A-4_Skyhawk&quot; rel=&quot;noreferrer&quot;&gt;A-4 Skyhawk&lt;/a&gt;, which shares many of its features, but even in looking through the variants, I can't find an exact match.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next two pictures aren't as clear, but they show the profile and wing shape, respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6KJ2i.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6KJ2i.jpg&quot; alt=&quot;profile&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hoQcr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hoQcr.jpg&quot; alt=&quot;wing shape&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three features I've noticed which set it apart from the A-4 variants I've found.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Wing shape - It's very curvy, almost Concorde-like.&lt;/li&gt;&#xA;&lt;li&gt;Vertical stabilizer - The forward section of the top of the vertical stabilizer is very sharp, whereas on the A-4's I've seen, this is curved.&lt;/li&gt;&#xA;&lt;li&gt;Antennae - There are &lt;em&gt;two&lt;/em&gt; antennae; one swept-back antenna directly behind the cockpit and a vertical antenna farther back where the vertical stabilizer begins.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I appreciate any guidance you can provide.  Thank you.&lt;/p&gt;&#xA;" OwnerUserId="13497" LastEditorUserId="14897" LastEditDate="2019-06-22T15:43:54.257" LastActivityDate="2019-06-22T15:43:54.257" Title="Can you help me identifying an A-4 Skyhawk-like jet?" Tags="&lt;aircraft-identification&gt;&lt;douglas-a-4-skyhawk&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25204" PostTypeId="2" ParentId="25203" CreationDate="2016-02-14T05:11:11.023" Score="16" Body="&lt;p&gt;They are A-4 Skyhawks all right. They are operated by &lt;a href=&quot;http://www.drakenintl.com/aircraft-inventory.html&quot; rel=&quot;noreferrer&quot;&gt;Draken International&lt;/a&gt; and &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/drakens-a-4k-skyhawks-provide-private-aggressor-duties-1749193650&quot; rel=&quot;noreferrer&quot;&gt;provide adversary training&lt;/a&gt; for USAF (among others); here's a closeup photo of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FX6QP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FX6QP.jpg&quot; alt=&quot;A-4 adversary&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.edwards.af.mil/shared/media/photodb/photos/2015/08/150821-F-IW159-002.jpg&quot; rel=&quot;noreferrer&quot;&gt;edwards.af.mil&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-14T05:11:11.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25205" PostTypeId="1" AcceptedAnswerId="25213" CreationDate="2016-02-14T05:53:46.467" Score="9" ViewCount="6260" Body="&lt;p&gt;The standard inbound/outbound holding leg are 1 min leg each (no wind condition). I noticed that a distance (4 nm in the following example) is noted in many GPS approaches. Do we need to fly the leg as 4 nm, or the number conveys other meanings?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g. &lt;a href=&quot;http://flightaware.com/resources/airport/TCY/IAP/RNAV+(GPS)+RWY+12/pdf&quot; rel=&quot;noreferrer&quot;&gt;http://flightaware.com/resources/airport/TCY/IAP/RNAV+(GPS)+RWY+12/pdf&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/R1Vsl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R1Vsl.jpg&quot; alt=&quot;RNAV (GPS) RWY 12 - TCY&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-02-14T06:08:59.860" LastActivityDate="2021-02-24T23:01:03.307" Title="Are we expected to fly distanced leg (instead of timed leg) in holding pattern in GPS approaches?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;holding&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25206" PostTypeId="2" ParentId="25205" CreationDate="2016-02-14T06:43:15.310" Score="5" Body="&lt;p&gt;Yes. The number denotes the distance of the holding pattern. From &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_3.pdf&quot;&gt;FAA Instrument Flying Handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;DME and IFR-certified GPS equipment offer some additional options for holding. Rather than being based on time, the leg lengths for DME/GPS holding patterns are based on distances in nautical miles. These patterns use the same entry and holding procedures as conventional holding patterns.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-14T06:43:15.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25208" PostTypeId="1" CreationDate="2016-02-14T09:07:47.373" Score="5" ViewCount="2209" Body="&lt;p&gt;Reading &quot;&lt;a href=&quot;http://documents.mx/documents/aea-requirements-long-range-aircraft.html&quot;&gt;Long Range Aircraft-AEA Requirements&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In appendix, Para 1.2 &quot;Definitions and specifications&quot;, the definition for &quot;Stage Length&quot; states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Stage length [...] for payload calculations includes 85% wind.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What does that mean?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="19" LastEditDate="2017-05-15T08:13:23.623" LastActivityDate="2017-05-15T08:13:23.623" Title="How to understand &quot;Stage length, for payload calculations includes 85% wind&quot;?" Tags="&lt;commercial-aviation&gt;&lt;fuel&gt;&lt;airlines&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25209" PostTypeId="2" ParentId="25208" CreationDate="2016-02-14T11:51:26.083" Score="4" Body="&lt;p&gt;The document &lt;a href=&quot;http://documents.mx/documents/aea-requirements-long-range-aircraft.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AEA Requirements Long Range Aircraft&lt;/a&gt; is related to airline fleet planning, and the calculation of the fuel needs. Note that it is dated Dec. 1987. More on &lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-75j-airline-management-spring-2006/lecture-notes/lect16.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;airline fleet planning&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;85% wind&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this planning the document from the airlines association recommends to assume the wind that has a probability to occur of 85%. That means: assume you will find this wind on your route 85% of the time. The wind force itself is determined talking into account statistics for the regions overflown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Stage&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight profile is provided on the document itself, defining &quot;stage&quot; as start of climb to end of descent, excluding initial climb:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WCxI5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WCxI5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Planning profitability&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knowing how much fuel will be required and by deduction how much payload can be transported allow airlines to estimate the airline costs and revenues on a given route with a given aircraft. This is important for planning aircraft acquisition and replacement, as well as the route catalog.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-02-17T21:49:43.867" LastActivityDate="2016-02-17T21:49:43.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25210" PostTypeId="2" ParentId="25132" CreationDate="2016-02-14T12:09:31.797" Score="0" Body="&lt;p&gt;Mig-21F, the first version of Mig-21 to be called as such, used a Tumansky R-11F-300 engine, which had a &lt;a href=&quot;http://www.topedge.com/panels/aircraft/sites/kraft/engine.htm&quot; rel=&quot;nofollow&quot;&gt;(variable) convergent nozzle&lt;/a&gt;. Later versions used Tumansky R-13-300, which was similar to the R-11 and Tumansky R-25-300 which had variable convergent nozzles as well. The Mig-27 used the Tumansky R29B, which &lt;a href=&quot;http://115.112.148.193/EngineKoraput/products.asp&quot; rel=&quot;nofollow&quot;&gt;has a convergent-divergent nozzle&lt;/a&gt; according to the manufacturer's site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, the aircraft speed is not limited by the exit speed, but the extra speed imparted to a mass of air by the engine (more the $\Delta v$, more the thrust). Basically, there is nothing that prevents an aircraft with convergent nozzle from attaining supersonic speeds, albeit the system is very ineffecient.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the designer is ready to accept a weight and fuel consumption penalty, he/she can use a supersonic convergent nozzle. Though this is ineffecient, for short duration, this would be acceptable.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another point to note is that the high exit temperatures means that the sonic velocities in the exhaust are nuch higher than the freestream ones. This means that the difference in speed is there, though the mach number may be less.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-14T12:09:31.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25212" PostTypeId="2" ParentId="25169" CreationDate="2016-02-14T14:52:09.190" Score="27" Body="&lt;p&gt;&lt;em&gt;&lt;strong&gt;What is a TRACON (Terminal Radar Approach CONtrol)?&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;A TRACON is a term used in the US for what is elsewhere known as the &lt;em&gt;&lt;a href=&quot;http://www.airportfreak.yolasite.com/airport-control.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Terminal Control&lt;/a&gt;&lt;/em&gt; (ICAO terminology), the control in charge of operations around one or more large airports. It doesn't manage ATC at airports, which is provided by TOWERs. TRACON is therefore an intermediate step used for:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Climbing departing flights received from TOWERs and handing them over to ARTCC.&lt;/li&gt;&#xA;&lt;li&gt;Descending cruising flights received from ARTCC and handing them over to airfield TOWERs&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uRw2a.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uRw2a.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.natca.org/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;FAA describes a TRACON &lt;a href=&quot;https://www.faa.gov/news/fact_sheets/news_story.cfm?contentkey=4009&quot; rel=&quot;nofollow noreferrer&quot;&gt;like this&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;TRACON controllers generally handle within a 30- to 50-mile radius of&#xA;an airport and up to 10 000 feet, as well as aircraft flying over that&#xA;airspace. They are responsible for the safe separation of aircraft&#xA;flying in the busy areas surrounding airports.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;When do pilots need to be helped by a TRACON?&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Pilots are directed to a TRACON center either by the Tower controller (for departures), or the ARTCC controller (for descents and transits). The services are delivered by radio from radar data. They typically encompass controlling aircraft during standard approach (STAR) and standard departures (SID). TRACON frequencies are mentioned on instrument plates as &lt;em&gt;Approach&lt;/em&gt; (APP CON) and &lt;em&gt;Departure&lt;/em&gt; (DEP CON), e.g. for Las Vegas (&lt;a href=&quot;https://skyvector.com/airport/LAS/Mc-Carran-International-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4Vnv3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4Vnv3.png&quot; alt=&quot;Approach control frequency on STAR&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Typical service provided to a descending aircraft (&lt;a href=&quot;https://ntrs.nasa.gov/api/citations/19900001525/downloads/19900001525.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Typically, arrival traffic is handed off from the ARTCC to the TRACON&#xA;air space at designated points, called feeder gates, about 30n.mi.&#xA;from the airport and 10,000 to 15,000ft above ground level. Some&#xA;airports utilize as many as four or five such gates or corner posts&#xA;which approximately form a rectangle with the airport at the center&#xA;[...]   Both feeder and final controllers attempt to keep aircraft on&#xA;a fastest or shortest path to the runway. They often utilize speed&#xA;changes, altitude changes, and path stretching to ensure proper&#xA;spacing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Similarly, climbing aircraft are directed via preferential departure routes towards the en-route airway, before being handed to Air Route Traffic Control Center (ARTCC).&lt;/p&gt;&#xA;&lt;p&gt;Controllers mostly use the Automated Radar Terminal System (ARTS) or the Standard Terminal Automation Replacement System (STARS) systems to track aircraft:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/guo3B.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/guo3B.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Philadelphia TRACON (&lt;a href=&quot;http://wiki.vzdc.org/tiki-index.php?page=Introduction+to+Radar&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;As emphasized by @TomMcW in his comment, smaller airfields don't have an associated TRACON, the approaches and departures are in this case directly managed by controllers at the airfield tower.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;Where are TRACON usually located?&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;TRACON &lt;em&gt;premises&lt;/em&gt; by themselves can be located anywhere. Controllers work on radar screens, in the half-light, they don't have a view of the outdoor. Basement rooms are usual.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CJrbK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CJrbK.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Potomac consolidated TRACON, operation room (&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Air_traffic_control#Approach_and_terminal_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Depending on the country they may be located close to major airports, within the area they control, preferably co-located with towers.&lt;/p&gt;&#xA;&lt;p&gt;TRACON &lt;em&gt;controlled areas&lt;/em&gt; are located around major airports.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In the US: &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/air_traffic_services/tracon/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA - Terminal Radar Approach Control Facilities&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;In Europe (TCC): See &lt;a href=&quot;https://aviation.stackexchange.com/questions/11548/can-multiple-airfields-be-in-the-same-airspace&quot;&gt;Can multiple airfields be in the same airspace?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/news/fact_sheets/news_story.cfm?contentkey=4009&quot; rel=&quot;nofollow noreferrer&quot;&gt;From FAA&lt;/a&gt; (where are TRACONs located?)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Some TRACONs are located on airport property and some are not, but&#xA;their locations have no effect on TRACON controllers’ ability to&#xA;control aircraft, or on the capacity or capabilities of any airport.&#xA;This is because TRACON controllers rely on radar displays and radio to&#xA;separate aircraft, unlike tower controllers who control landings and&#xA;takeoffs visually. In fact, TRACONs do not have windows — a darker&#xA;environment makes it easier for controllers to see the radar screens.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The article mentions cases like &lt;a href=&quot;https://en.wikipedia.org/wiki/New_York_TRACON&quot; rel=&quot;nofollow noreferrer&quot;&gt;N90 TRACON&lt;/a&gt;: It controls traffic from/to major airports in NY area (La Guardia, JFK, Newark Liberty), but is located on Long Island, a location remote from these airports.&lt;/p&gt;&#xA;&lt;p&gt;FAA arguments for tower and TRACON co-location include savings and easier 24/7 uninterrupted operations.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;What is the difference between TRACON, En Route and Tower?&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Taking the US ATC system only into account for this discussion. The difference should have been clarified above: Towers handle airport operations, ARTCCs/En-route handle cruise phase, and TRACONs handle climbing and descending aircraft, as well as aircraft transiting between ARTCCs in their controlled areas. Here are some details about Towers and ARTCCs.&lt;/p&gt;&#xA;&lt;p&gt;1/ &lt;strong&gt;Airport operations&lt;/strong&gt; are controlled by controllers in the &lt;em&gt;tower&lt;/em&gt;. They need a view on the runways and other location of the airport.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iiUUj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iiUUj.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Tower at Nice / Côte d'Azur airport (&lt;a href=&quot;https://www.iao-project.eu/wp/?page_id=194&quot; rel=&quot;nofollow noreferrer&quot;&gt;LFMN&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Radar techniques are used for tracking aircraft on the ground (ASDE-X) and informations from short range radars can feed various displays, of which the &lt;a href=&quot;https://www.airport-data.com/airport/photo/007337.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;D/BRITE&lt;/a&gt; (Digital Bright Radar Indicator Tower Equipment), and more modern Barco.&lt;/p&gt;&#xA;&lt;p&gt;Takeoff and landing clearances are delivered after visual check of the runway status.&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://virtualskies.arc.nasa.gov/atm/4.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nasa's page&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Control towers were established to provide for a safe, orderly, and&#xA;expeditious flow of air traffic at an airport and in its vicinity.&#xA;There are four major controller classifications at control towers:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flight Data Controller&lt;/li&gt;&#xA;&lt;li&gt;Clearance Delivery Controller&lt;/li&gt;&#xA;&lt;li&gt;Ground Controller&lt;/li&gt;&#xA;&lt;li&gt;Local Controller.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vQU9s.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vQU9s.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Inside an air traffic control tower (&lt;a href=&quot;https://www.reddit.com/r/pics/comments/3gx0ng/inside_an_air_traffic_control_tower/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;p&gt;2/ &lt;strong&gt;Enroute traffic&lt;/strong&gt; is controlled by &lt;em&gt;Air Route Traffic Control Center&lt;/em&gt; (ARTCC)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sdrvw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sdrvw.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Typical sector radar team (&lt;a href=&quot;https://www.reddit.com/r/AskReddit/comments/40axat/people_who_work_for_airlines_what_are_secrets&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;http://virtualskies.arc.nasa.gov/atm/6.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nasa's page&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;ARTCCs, usually referred to as &amp;quot;Centers,&amp;quot; are established primarily to&#xA;provide Air Traffic Service to aircraft operating on IFR flight plans&#xA;within the controlled airspace, and principally during the en route&#xA;phase of flight.&lt;/p&gt;&#xA;&lt;p&gt;There are 21 Air Route Traffic Control Centers (ARTCC) in the United&#xA;States.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PcvLF.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PcvLF.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;US ARTCC boundaries (&lt;a href=&quot;https://www.reddit.com/r/aviation/comments/3674wr/us_air_traffic_control_zones/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Any aircraft operating under Instrument Flight Rules (IFR) within the&#xA;confines of an ARTCC's airspace is controlled by air traffic&#xA;controllers at the Center. This includes all sorts of different types&#xA;of aircraft: privately owned single engine aircraft, commuter&#xA;airlines, military jets and commercial airlines.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;ARTCC manages flights between TRACON airspaces, while they are cruising at high altitude.&lt;/p&gt;&#xA;&lt;p&gt;(You can listen to ARTCC traffic at &lt;a href=&quot;https://www.liveatc.net/feedindex.php?type=us-artcc&quot; rel=&quot;nofollow noreferrer&quot;&gt;LiveATC.net&lt;/a&gt;)&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Read more:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Air_traffic_control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air traffic control&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/New_York_TRACON&quot; rel=&quot;nofollow noreferrer&quot;&gt;New York TRACON&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.atcsuite.com/index_tracon.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;TRACON 2012&lt;/a&gt;, the game&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.faa.gov/news/fact_sheets/news_story.cfm?contentkey=4009&quot; rel=&quot;nofollow noreferrer&quot;&gt;Co-Located TRACONS&lt;/a&gt; (FAA)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://old.vatusa.net/training/tiki-index.php?page=atc_positions_and_functions&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC Positions and Functions&lt;/a&gt; (VATUSA, ATC simulation)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2021-02-10T12:08:34.727" LastActivityDate="2021-02-10T12:08:34.727" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="25213" PostTypeId="2" ParentId="25205" CreationDate="2016-02-14T15:09:31.677" Score="7" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&lt;p&gt;Yes, the pilot is expected to fly the hold as depicted, with an outbound leg based on distance (see &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0503.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-3-7&lt;/a&gt;, paragraph b). Most holds depicted on GPS instrument approaches in the US now have a specified distance for the outbound hold leg, instead of a timed leg.&lt;/p&gt;&#xA;&lt;h2&gt;Longer Answer:&lt;/h2&gt;&#xA;&lt;p&gt;The traditional hold leg distance is determined by timing. See &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0503.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-3-7&lt;/a&gt; § j. 4.:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;4. Timing.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(a) Inbound Leg.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(1)&lt;/strong&gt; At or below 14,000 feet MSL: 1 minute.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(2)&lt;/strong&gt; Above 14,000 feet MSL: 11/2 minutes.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;NOTE-&lt;/strong&gt; The initial outbound leg should be flown for 1 minute or 1 1/2 minutes (appropriate to altitude). Timing for subsequent outbound legs&#xA;should be adjusted, as necessary, to achieve proper inbound leg time.&#xA;Pilots may use any navigational means available; i.e., DME, RNAV,&#xA;etc., to ensure the appropriate inbound leg times.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;(b) Outbound leg&lt;/strong&gt; timing begins over/abeam the fix, whichever occurs&#xA;later. If the abeam position cannot be determined, start timing when&#xA;turn to outbound is completed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In years past this was common for all holds, unless otherwise specified by the published hold instructions, or by ATC. All otherwise unspecified holds were assumed to be timed holds, including for GPS approaches. I only remember a few distance-defined holds in my local area from 10 years ago; now all those holds associated with GPS instrument approaches are distance defined.&lt;/p&gt;&#xA;&lt;p&gt;Which brings us to the &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0503.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-3-7&lt;/a&gt; § j. 5. (emphasis on the last two sentences is mine):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;5. Distance Measuring Equipment (DME)/ GPS Along-Track Distance (ATD).&lt;/strong&gt; DME/GPS holding is subject to the same entry and holding procedures except that distances (nautical miles) are used in lieu of time values. The outbound course of the DME/GPS holding pattern is called the outbound leg of the pattern. The controller or the instrument approach procedure chart will specify the length of the outbound leg. The end of the outbound leg is determined by the DME or ATD readout. The holding fix on conventional procedures, or controller defined holding based on a conventional navigation aid with DME, is a specified course or radial and distances are from the DME station for both the inbound and outbound ends of the holding pattern. &lt;em&gt;&lt;strong&gt;When flying published GPS overlay or stand alone procedures with distance specified, the holding fix will be a waypoint in the database and the end of the outbound leg will be determined by the ATD. Some GPS overlay and early stand alone procedures may have timing specified.&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;See also &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0503.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM Fig 5-3-7&lt;/a&gt; and the associated note, which address the type of distance holds found on GPS approaches:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/npBoO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/npBoO.png&quot; alt=&quot;AIM Fig 5-3-7&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;&#xA;The inbound course is always toward the waypoint and the ATD is zero at the waypoint. The end of the outbound leg of the holding pattern is reached when the ATD reads the specified distance.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The holds found on GPS approaches will generally be distance based. The AIM states that some might still be time based, but I am no longer aware of any such holds in actuality. Every approach that I know of that used to have a time based hold on a GPS approach now has a distance based hold.&lt;/p&gt;&#xA;&lt;p&gt;All holds should be flown as published or as instructed by ATC. If ATC does not instruct you otherwise, you are expected to fly the hold as published. In this case, that means you are expected to fly the hold as a distance-based hold. If you are not sure how you should fly the hold, ask ATC. They will provide you with the complete holding instructions if requested. See &lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/AIM/Chap5/aim0503.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-3-7&lt;/a&gt; § b.:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; If the holding pattern is charted and the controller doesn't issue&#xA;complete holding instructions, the pilot is expected to hold as&#xA;depicted on the appropriate chart. When the pattern is charted, the&#xA;controller may omit all holding instructions except the charted&#xA;holding direction and the statement AS PUBLISHED; e.g., HOLD EAST AS&#xA;PUBLISHED. Controllers shall always issue complete holding&#xA;instructions when pilots request them.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2021-02-24T12:19:02.960" LastActivityDate="2021-02-24T12:19:02.960" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25214" PostTypeId="1" AcceptedAnswerId="25219" CreationDate="2016-02-14T15:47:57.980" Score="15" ViewCount="6736" Body="&lt;p&gt;During pre-flight which direction should I be rotating the propeller of a Cessna 172 if I need to reach the alternator belt?  I thought I was told &quot;In the direction it rotates during flight&quot;; however I feel there was some misunderstanding. Isn't there the possibility of accidentally hand propping if I do it that way on a warm engine? Today I rotated it clockwise in the direction of the blade and it kicked over and popped me in the knee (leg shouldn't have been there - lesson learned!) Please help me clarify!&lt;/p&gt;&#xA;" OwnerUserId="12677" LastEditorUserId="12220" LastEditDate="2016-02-14T16:08:20.793" LastActivityDate="2016-02-15T17:49:28.313" Title="Which way should I rotate the propeller of a C172?" Tags="&lt;propeller&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25215" PostTypeId="1" AcceptedAnswerId="25223" CreationDate="2016-02-14T16:58:01.270" Score="15" ViewCount="3595" Body="&lt;p&gt;For example, if a plane is flying from Amsterdam to Miami and is in the middle of the ocean, who manages that traffic? The ARTCC? Or the airplane just flies without communicating for some hours until it reaches an ARTCC area?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-14T17:08:57.470" LastActivityDate="2021-02-12T14:09:10.880" Title="Who manages International Airspace Traffic?" Tags="&lt;air-traffic-control&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25217" PostTypeId="1" AcceptedAnswerId="25228" CreationDate="2016-02-14T17:15:34.403" Score="8" ViewCount="3308" Body="&lt;p&gt;I understand that (from other answers) planes taxi using engines only. But, when I'm a passenger, then why do I hear the &quot;real&quot; engine noise only when the plane is on the runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, if planes taxi till runway using engines only, then why don't I hear that much noise until the aircraft reaches the runway?&lt;/p&gt;&#xA;" OwnerUserId="13502" LastEditorUserId="946" LastEditDate="2016-02-15T18:06:06.150" LastActivityDate="2016-02-15T20:00:05.823" Title="Why do I hear the &quot;real&quot; engine noise only when the plane is on the runway?" Tags="&lt;commercial-aviation&gt;&lt;taxiing&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25218" PostTypeId="1" AcceptedAnswerId="25221" CreationDate="2016-02-14T17:33:19.390" Score="10" ViewCount="2294" Body="&lt;p&gt;I've noticed a grey line on the flaps of the A319:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9QTma.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9QTma.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that?&lt;br&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Northwest-Airlines/Airbus-A319-114/1155164/&amp;amp;sid=0e373b27976ef8bee7c8e931e517ce10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T18:07:41.390" LastActivityDate="2016-03-05T18:07:41.390" Title="What are these &quot;lines&quot; on the A319 flaps, are they damaged?" Tags="&lt;airliner&gt;&lt;wing&gt;&lt;aircraft-maintenance&gt;&lt;airbus-a320&gt;&lt;flaps&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25219" PostTypeId="2" ParentId="25214" CreationDate="2016-02-14T17:34:07.333" Score="12" Body="&lt;p&gt;Avoid rotating the propeller through a compression of one of the cylinders.  You can easily rotate the propeller in either direction safely about 45 degrees before you feel a cylinder in compression. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to pull the propeller completely through a compression stroke you must be prepared for it to snap around after reaching the top of the compression stroke and that is how you must have whacked your knee. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally after an engine shutdown the mixture is pulled to idle cutoff which would prevent fuel reaching the cylinders.  Also if procedures are followed the magnetos that generate ignition sparks should be off after the end of a flight. So in theory it should be safe to pull the propeller thru during preflight. But still you need to consider that it is not completely without some small risk that the engine could start simply because humans make errors and machines can need maintenance. &lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-02-14T17:34:07.333" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25220" PostTypeId="1" CreationDate="2016-02-14T17:40:39.183" Score="4" ViewCount="1033" Body="&lt;p&gt;I am making a project which includes automation of aileron, rudder and elevator deflection. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a quantifiable relation which can tell me the amount of deflection required for any radius of turn if the other parameters are put constants.&lt;/p&gt;&#xA;" OwnerUserId="13503" LastEditorUserId="69" LastEditDate="2016-02-15T04:28:01.537" LastActivityDate="2017-05-29T02:58:21.590" Title="Is there a relationship between control surface deflection and a particular turn radius or bank angle?" Tags="&lt;aerodynamics&gt;&lt;maneuver&gt;&lt;control-surfaces&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25221" PostTypeId="2" ParentId="25218" CreationDate="2016-02-14T17:42:07.970" Score="13" Body="&lt;p&gt;You are seeing the steel reinforcing sheet metal at the line where the spoilers rest on the flaps when both are retracted.  It is there as a bearing surface since there is some inevitable contact between the spoilers and the top surface of the flap when they are both retracted during flight.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-02-14T17:42:07.970" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25222" PostTypeId="2" ParentId="25220" CreationDate="2016-02-14T18:03:14.963" Score="0" Body="&lt;p&gt;Aileron deflection affects your roll &lt;em&gt;rate&lt;/em&gt;, but you can roll rapidly or slowly to whatever chosen angle of bank... and the angle of bank (along with true airspeed) is what determines your turn rate and radius. (Assuming a coorinated turn.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on various parameters, some small amount of rudder and elevator deflection may be necessary to maintain coordinated level flight once established in the turn, and depending on the aircraft, you may need some rudder input while the ailerons are deflected.  That's all pretty well specific to whatever aircraft you're modeling.  In a swept-wing jet, &lt;em&gt;significant&lt;/em&gt; rudder deflection is not required (and what little deflection is needed is often provided by the yaw damper rather than the pilot), while in a long-winged glider with considerable adverse yaw, adding a fair bit of rudder along with aileron is required for coordinated flight.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-02-15T03:32:40.730" LastActivityDate="2016-02-15T03:32:40.730" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25223" PostTypeId="2" ParentId="25215" CreationDate="2016-02-14T18:19:24.910" Score="24" Body="&lt;p&gt;&lt;strong&gt;Global ATC in general&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;In the civil aviation domain, international rules are proposed by &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Civil_Aviation_Organization&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO&lt;/a&gt;. The foundations of these laws have been agreed in 1944 under the &lt;a href=&quot;https://en.wikipedia.org/wiki/Chicago_Convention_on_International_Civil_Aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chicago Convention&lt;/a&gt;, in particular its &lt;a href=&quot;https://www.bazl.admin.ch/dam/bazl/en/dokumente/Fachleute/Regulationen_und_Grundlagen/icao-annex/icao_annex_2_rulesoftheair.pdf.download.pdf/icao_annex_2_rulesoftheair.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Annex 2, Rules of the Air&lt;/a&gt;. &lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/3722.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nearly all countries&lt;/a&gt; are signatories of this convention.&lt;/p&gt;&#xA;&lt;p&gt;ICAO global airspace structure is divided into large &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_information_region&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Information Regions&lt;/a&gt; (FIR -- their upper layer being conventionally named UIR). A FIR over a domestic airspace is under the responsibility of the country below. A FIR over the international airspace (e.g. airspace over international waters) is under the responsibility of a single ICAO member state which has received a delegation from ICAO.&lt;/p&gt;&#xA;&lt;p&gt;Within a FIR, enroute services are provided by &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_Area_Control_Centers&quot; rel=&quot;nofollow noreferrer&quot;&gt;Area Control Centers&lt;/a&gt; or ACC (ARTCC is the FAA local name for ICAO ACC). The first services available (and guaranteed) are &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_information_service&quot; rel=&quot;nofollow noreferrer&quot;&gt;information&lt;/a&gt; and &lt;a href=&quot;https://aviationsafetywiki.org/index.php/Alerting_Service&quot; rel=&quot;nofollow noreferrer&quot;&gt;alerting&lt;/a&gt;. Control services like separation can be provided, depending on the FIR.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;(That's unfortunately a lot of acronyms, and more are coming soon... I give them only for precision in case someone wants to dig further into details, but you don't need to remember them to understand the system.)&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Specificity of Oceanic Control&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;When a FIR provides control services over an ocean area, such area is named Oceanic Control Area or OCA, and the corresponding ACC are named Oceanic Area Control Centers (OAC). OAC and ACC differ by the procedures they can use to provide their services: ACC are able to track aircraft using reliable radars, while OAC mostly work with voice/data position reports from crews over unreliable long distance communications (that's less and less true with modern means like &lt;a href=&quot;https://www.icao.int/SAM/Documents/2017-ADSB/15%20Aireon-NAM%20CAR%20SAM%20ADS-B%20WS%20v4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;space-based ADS-B&lt;/a&gt; and ACARS/CPDLC/DCPC (see Guidance Material for ATS Data Link Services in NAT Airspace &lt;a href=&quot;http://code7700.com/pdfs/nat/nat_datalink.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;North Atlantic case&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;All flights which want to maximize (eastbound) or minimize (westbound) the effects of high altitude &lt;a href=&quot;https://sites.google.com/site/acnetworkweather/home/north-atlantic&quot; rel=&quot;nofollow noreferrer&quot;&gt;jet streams of the day&lt;/a&gt; over the Atlantic Ocean must use the crowded &lt;a href=&quot;https://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot; rel=&quot;nofollow noreferrer&quot;&gt;North Atlantic Organized Track System&lt;/a&gt; (NAT-OTS, not to be confused with &lt;a href=&quot;https://en.wikipedia.org/wiki/NATS_Holdings&quot; rel=&quot;nofollow noreferrer&quot;&gt;NATS Holdings&lt;/a&gt;, the UK ANSP) when flying at or above FL55. They must obtain an oceanic clearance from the first OAC before reaching their entry point into the NAT-OTS. So to answer directly your question:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The crew using the track system will be in contact with the OCA/OAC controllers during the flight between domestic areas. However to bear with possible unreliability of HF radio transmissions, this contact doesn't have to be permanent. Instead it may occur only at intermediate reporting points spaced by 10° longitude.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;They will also be in contact with FIR/ACC controllers prior to entering and after leaving the OCA/OAC.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Transition areas (OTA) exist to bridge between ACC and OAC: See areas ending in &amp;quot;OTA&amp;quot; in the &lt;a href=&quot;http://occ.ivao.aero/upload/EGGXAirspace.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shanwick FIR/OCA&lt;/a&gt;, like BOTA for Brest OTA, bridging Shanwick OTA (UK) with Brest FIR/UIR (domestic France). In OTA, traffic is handled by the regular domestic FIR (actually its &lt;a href=&quot;https://en.wikipedia.org/wiki/Upper_information_region&quot; rel=&quot;nofollow noreferrer&quot;&gt;UIR&lt;/a&gt;, given the altitude flown at this stage) rather than the OCA.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;North Atlantic ocean is covered by 6 OCA managed by different ICAO member States: UK (&lt;a href=&quot;https://en.wikipedia.org/wiki/Shanwick_Oceanic_Control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shanwick&lt;/a&gt;), Iceland (&lt;a href=&quot;https://www.isavia.is/en/corporate/air-navigation/reykjavik-control-centre/reykjavik-control-area&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reykjavik&lt;/a&gt;), Canada (&lt;a href=&quot;https://en.wikipedia.org/wiki/Gander_Automated_Air_Traffic_System&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gander&lt;/a&gt;), Norway (Bodø), USA (NY West) and Portugal (Santa Maria).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C5Y0h.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C5Y0h.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;North Atlantic OCAs (source ICAO, now removed from the site)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;A common route for the flight you mention will cross &lt;a href=&quot;https://en.wikipedia.org/wiki/Shanwick_Oceanic_Control&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shanwick&lt;/a&gt; and &lt;a href=&quot;http://www.gcmap.com/airport/CZQX&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gander&lt;/a&gt; OCA.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pKRqG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pKRqG.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(source &lt;a href=&quot;https://fr.flightaware.com/live/flight/KYE4851/history/20160221/1704Z/EHAM/KMIA&quot; rel=&quot;nofollow noreferrer&quot;&gt;FlightAware&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;FIRs and their boundaries worldwide can be displayed with this &lt;a href=&quot;https://gis.icao.int/ICAOAVIATION/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO GIS viewer&lt;/a&gt; (be patient at the first use, background resources take time to load):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FeIU1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FeIU1.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(source: &lt;a href=&quot;https://gis.icao.int/ICAOAVIATION/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO FIR viewer&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2021-02-12T14:09:10.880" LastActivityDate="2021-02-12T14:09:10.880" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="25225" PostTypeId="1" CreationDate="2016-02-14T19:17:50.830" Score="4" ViewCount="391" Body="&lt;p&gt;Pitch moment is created by lift created by the horizontal stabilizers via the elevators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then main wings also create lift, why does not this lift enough to create pitch moment?&lt;/p&gt;&#xA;" OwnerUserId="13502" LastEditorUserId="12220" LastEditDate="2016-02-14T19:24:36.947" LastActivityDate="2019-08-14T05:34:35.793" Title="Why does not the lift produced by main wings create pitch moment?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;elevator&gt;&lt;pitch&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25226" PostTypeId="2" ParentId="25225" CreationDate="2016-02-14T20:07:58.763" Score="8" Body="&lt;p&gt;Of course it creates a pitching moment! Now we need to define around which reference point this moment should be measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the reference point is the center of gravity, it is even equally strong as the pitching moment of the elevator, it only has the opposite direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use the aerodynamic center as the reference point, the moment will be less strong. If the wing airfoil is symmetric, the moment will actually be zero (ideally), but with a cambered airfoil there is still a measurable moment left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A moment is always a combination of a force and a lever arm, measured perpendicular to the direction of the force. Only when the lever arm is zero will the moment disappear. If we use the center of gravity as the reference point, the weight will have no lever arm and will contribute no moment, but the distance between the wing's lift and the center of gravity is large, so this moment is large, too.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-14T22:16:34.817" LastActivityDate="2016-02-14T22:16:34.817" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25227" PostTypeId="2" ParentId="25214" CreationDate="2016-02-14T20:11:12.613" Score="14" Body="&lt;p&gt;Almost everyone in the industry has opinions about this, sometimes with good reason. I know knowledgeable people with good arguments for why you should only turn the prop backwards, never turn the prop backwards, or why it doesn't matter either way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, the issues of concern are primarily:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The engine firing and rotating the propeller, or&lt;/li&gt;&#xA;&lt;li&gt;The dry vacuum pump sustaining damage.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Those who say &quot;you should never turn a prop forwards,&quot; will typically argue that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rotating the prop in the firing direction can cause the engine to fire, &lt;em&gt;if&lt;/em&gt;:  &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A magneto (with an impulse coupling) is live (faulty ground or actually switched on), and&lt;/li&gt;&#xA;&lt;li&gt;The cylinder still has a burnable fuel/air mixture (particularly if recently not properly shut-down).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Rotating the prop backwards eliminates the possibility of the impulse coupling catching and sending a spark to any cylinder.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Those who say &quot;you should never turn a prop backwards,&quot; will typically argue that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Dry vacuum pumps are fragile and only meant to be turned in one direction (with normal engine rotation), and&lt;/li&gt;&#xA;&lt;li&gt;Rotating the prop backwards introduces the possibility of damaging the vacuum pump's (relatively) delicate carbon vanes leading to pump failure.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Those who hold that either direction is potentially dangerous but can be done with caution will typically argue that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Backward movement of the prop—especially small, gentle, cautious movement—introduces little likelihood of damage to the vacuum pump vanes;&lt;/li&gt;&#xA;&lt;li&gt;Good engine shutdown and magneto switch policing will very nearly eliminate the possibility of an inadvertent cylinder firing, and&lt;/li&gt;&#xA;&lt;li&gt;Carefully moving the prop forward while treating the engine as live will give you a good margin of safety.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;One may present a variation on the above, but I think those three perspectives capture the essence of any argument on this topic. Inadvertent engine firing can indeed be very dangerous, and a piston prop should be treated as live and dangerous. Dry vacuum pumps are indeed built with carbon or composite vanes which are far more brittle and delicate than steel parts. However, there are differing takes on just &lt;em&gt;how&lt;/em&gt; delicate these are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tRLTr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tRLTr.jpg&quot; alt=&quot;Dry Vacuum Pump&quot;&gt;&lt;/a&gt;&#xA;&lt;sub&gt;&lt;em&gt;&quot;Healthy dry air pump, left, showing graphite vanes angled in carbon rotor. When an air pump fails, its rotor and vanes often shatter&quot;&lt;/em&gt; — Photo and caption as seen in &lt;a href=&quot;http://www.aviationconsumer.com/issues/45_6/maintenancematters/Vacuum-Pump-411-Continually-Improving_6765-1.html&quot; rel=&quot;noreferrer&quot;&gt;Aviation Consumer&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Australian Civil Aviation Safety Authority (CASA) &lt;a href=&quot;https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/airworth/awb/37/003.pdf&quot; rel=&quot;noreferrer&quot;&gt;states that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Simply pulling the propeller backwards to “test” cylinder compressions may fail the pump by forcing the vanes to rotate in a direction opposite to their intended design. In order to prevent the vacuum pumps from being operated in reverse, never turn the propeller backwards.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, Aviation Consumer states &lt;a href=&quot;http://www.aviationconsumer.com/issues/45_6/maintenancematters/Vacuum-Pump-411-Continually-Improving_6765-1.html&quot; rel=&quot;noreferrer&quot;&gt;in this article&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;One of aviation’s old wives’ tales is that you’ll wreck your vacuum pump if you move the prop backward. Fortunately, that’s not true. While most vacuum pumps are unidirectional—they either turn clockwise or counterclockwise in service based on the direction of rotation of the accessory shaft on the engine (and have CC or CW as a suffice to their model number)—it takes more than a few turns in the wrong direction to cause damage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Mike Berry, whose opinion on such matters I respect, seems to think that turning the prop backwards will not hurt it, as seen in this quote from his May 2002 article in &lt;em&gt;Light Plane Maintenance&lt;/em&gt;, &lt;a href=&quot;http://www.avweb.com/news/maint/182825-1.html&quot; rel=&quot;noreferrer&quot;&gt;reprinted by AvWeb.com&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By the way, pulling a prop through backwards will not hurt a dry pump.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know people that operate and maintain several Cessnas with dry vacuum pumps and are not very gentle when they move the prop either forward or backward they don't seem to have issues either with the engine firing or with low vacuum pump replacement intervals. The vacuum pumps replacements that I have done were typically brought about by normal long-term wear, as far as I can tell.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My take is: firstly, know your aircraft and it's systems. Secondly, be careful; respect the prop. Personally, I turn the prop either direction, but not usually a lot, and I do so gently and cautiously.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-15T17:49:28.313" LastActivityDate="2016-02-15T17:49:28.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25228" PostTypeId="2" ParentId="25217" CreationDate="2016-02-14T20:20:28.890" Score="35" Body="&lt;p&gt;When you have the thrust levers of, say, a 747 all the way back to idle, the airplane still has enough power to move. In fact, you will have to use the brakes to keep it from taxiing too fast. If you didn't use the brakes, it would finally accelerate to somewhere around 45 knots or so, far too fast for taxiing, but much too slow to take off. At the idle power setting, relatively little noise is produced by the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To take off, if the 747 were at max gross, you would have to accelerate to around 180 knots. That would require a power setting approaching the maximum, depending on the length of the runway. The noise produced by the engines is relative to the amount of power they're producing. Hence, taxiing at idle produces little noise relatively speaking, on the runway taking off a whole lot of noise.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-02-15T20:00:05.823" LastActivityDate="2016-02-15T20:00:05.823" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25229" PostTypeId="1" AcceptedAnswerId="25235" CreationDate="2016-02-14T20:56:20.777" Score="10" ViewCount="2301" Body="&lt;p&gt;I have heard that when the &lt;a href=&quot;https://en.wikipedia.org/wiki/R-73_(missile)&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vympel R-73&lt;/a&gt; air-to-air missile was introduced it was a game-changer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have also heard that after the collapse of the Soviet block it was tested by NATO (via re-united Germany) and NATO was quite impressed by it. According to one source, in close combat the MiG-29 was better than the F-16 by 2:1 and better than the F/A-18 by 1.5:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What was so special about it? How did they make it? Did they have better experiences? Or ideas?&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="15311" LastEditDate="2018-06-15T14:50:21.080" LastActivityDate="2018-06-15T20:26:45.720" Title="In what manner was the Vympel R-73 (AA-11 Archer) a game-changer in comparison with NATO's missiles?" Tags="&lt;military&gt;&lt;missiles&gt;&lt;russia&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="25230" PostTypeId="2" ParentId="25220" CreationDate="2016-02-14T21:02:36.933" Score="5" Body="&lt;p&gt;You need the ailerons only to bank the aircraft; once the bank angle is reached, the aileron deflection is mostly close to zero. I assume we are talking about stationary turns, so speed and aircraft mass will not change significantly over the duration of the turn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While turning, several moments need to be balanced to keep the roll angle constant, and a good design does this without requiring aileron input:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The rotation around the vertical axis causes more airspeed over the outer wing, increasing its lift. This causes a rolling moment into the turn.&lt;/li&gt;&#xA;&lt;li&gt;The rotation around the vertical axis causes a sideslip condition at the vertical tail which causes a yawing moment against the turn.&lt;/li&gt;&#xA;&lt;li&gt;The inertial forces try to pull the wings level. This causes a rolling moment against the turn.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, the elevator needs to be held at a slightly more negative angle than in level flight to pull the required load factor $n_z$. In a turn, the load factor is proportional to the bank angle $\Phi$:&#xA;$$n_z = \frac{1}{cos \,\Phi}$$&#xA;Radius $R$: $$R = \frac{v^2}{g\cdot tan\,\Phi}$$&#xA;Angular velocity $\Omega$ (rad/sec): $$\Omega = \frac{v}{R} = \frac{g\cdot tan\,\Phi}{v}$$&#xA;The amount of elevator deflection needed depends on the stability margin (expressed as $\frac{c_{m\alpha}}{c_{L\alpha}}$) of the airplane, its pitch damping (expressed as $c_{mq}$) and elevator effectiveness (expressed as $c_{m\eta_H}$). &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-14T22:21:28.207" LastActivityDate="2016-02-14T22:21:28.207" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25231" PostTypeId="1" AcceptedAnswerId="25232" CreationDate="2016-02-14T21:30:40.463" Score="6" ViewCount="14849" Body="&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Ceiling: what is the ceiling? Why do they need to know the ceiling?&lt;/li&gt;&#xA;&lt;li&gt;Zulu time: what is the zulu time?&lt;/li&gt;&#xA;&lt;li&gt;Dew point: why do they need to know the dew point?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-30T16:55:45.583" LastActivityDate="2016-03-30T22:32:08.813" Title="Why do pilots need the ceiling, time, and dew point in the ATIS?" Tags="&lt;weather&gt;&lt;pilots&gt;&lt;atis&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25232" PostTypeId="2" ParentId="25231" CreationDate="2016-02-14T21:52:08.547" Score="28" Body="&lt;p&gt;The ceiling is the lowest altitude where clouds cover more than half of the sky. This is important because climbing above that altitude means you will most likely have to fly through clouds. &lt;a href=&quot;https://aviation.stackexchange.com/q/12208/1696&quot;&gt;This makes navigation more difficult&lt;/a&gt; and pilots are required to have special training to fly in low visibility. If the ceiling is too low, pilots can't be at a safe altitude above the ground and out of the clouds at the same time. Low ceilings are also critical for landing, and may require pilots to make an &lt;a href=&quot;https://aviation.stackexchange.com/q/2620/1696&quot;&gt;instrument approach and landing&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/16818/1696&quot;&gt;Zulu time&lt;/a&gt; refers to UTC time, which is the universal coordinated time. Zulu or UTC time is helpful as a worldwide reference in fields like aviation, to avoid issues like dealing with changing between local time zones. The ATIS will contain the Zulu time that it was updated so pilots know how recent the information is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dew point in relation to the temperature gives the pilots information about the humidity, and can affect visibility. If the dew point is close to the temperature, humidity is high, which can cause hazy conditions, or even fog. As with the ceiling, this can warn pilots of possible changes in conditions that will make it harder to see the ground or other aircraft while in flight. In terms of aircraft performance, the dew point is also needed to determine the true &lt;a href=&quot;https://en.wikipedia.org/wiki/Density_altitude&quot; rel=&quot;nofollow noreferrer&quot;&gt;density altitude&lt;/a&gt;, when &lt;a href=&quot;http://www.srh.noaa.gov/epz/?n=wxcalc_densityaltitude&quot; rel=&quot;nofollow noreferrer&quot;&gt;combined with the pressure and temperature&lt;/a&gt;. A high dew point means a higher density altitude, which reduces aircraft performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dew point is also very important in certain helicopters with carburetors, like the Robinson R-22 and R-44 helicopters, which are subject to carb icing even during take-off because they only use as-required power rather than full throttle. In this case, carb heat needs to be applied whenever the temp/dew point spread is 15C or less. Here is the citation from the &lt;a href=&quot;http://www.robinsonheli.com/service_library/safety_notices/rhc_sn25.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;R-22 POH&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Tilx9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Tilx9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-02-19T18:18:54.650" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25233" PostTypeId="2" ParentId="25229" CreationDate="2016-02-14T21:52:51.280" Score="2" Body="&lt;p&gt;According to &lt;a href=&quot;http://fas.org/man/dod-101/sys/missile/row/aa-11.htm&quot; rel=&quot;nofollow&quot;&gt;this &lt;/a&gt;article, the main reasons were its exceptional mobility and accuracy. It can maneuver well enough to hit an aircraft in a 12 G turn, and has incredible accuracy, due to a direct connection with the pilots HUD, sophisticated infrared targeting, and a system called a &quot;transverse control engine&quot; (the details of which are apparently classified) to ensure that the target can't out maneuver it at the last second. &lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-02-14T21:52:51.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25234" PostTypeId="2" ParentId="25229" CreationDate="2016-02-14T22:28:42.223" Score="9" Body="&lt;p&gt;Yes, the Russians had the better ideas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key was the slaving of the radar system to the pilot's helmet, called &lt;a href=&quot;http://www.ausairpower.net/hmd-technology.html&quot;&gt;sight-controlled missile targeting&lt;/a&gt;: The missile would lock to whatever the pilot was looking at. In combination with the wide off-boresight capabilities of the aircraft's radar and the missiles, it even allowed to get a lock on aircraft flying actually behind it. When US F-16s met ex-GDR MiGs in exercises in the early 1990s, they were shocked to find &lt;a href=&quot;http://web.archive.org/web/20130330032841/http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=8672&quot;&gt;how much superior&lt;/a&gt; the Russian design was.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the second link:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;With the Phazotron NIIR N019 Doppler radar (NATO designation &quot;Slot&#xA;  Back&quot;) capable of detecting a target more than 60 miles away, infrared&#xA;  tracking sensors, and a laser rangefinder carried on the MiG-29, a&#xA;  pilot could track and shoot at aircraft flying below him. Also, the&#xA;  pilot's Shchel-3UM-1 helmet-mounted aiming device turned the MiG-29&#xA;  into a very dangerous threat once opponents came within visual range.&#xA;  No longer did a pilot have to turn his aircraft toward a target and&#xA;  wait for his missiles' sensors to &quot;lock-on&quot; before firing. Now, the&#xA;  pilot simply turned his head toward a target, and the helmet aimed the&#xA;  missile's sensors toward the target. This &quot;off boresight&quot; procedure&#xA;  gave the MiG-29 pilot a great advantage at close range.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-14T22:28:42.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25235" PostTypeId="2" ParentId="25229" CreationDate="2016-02-14T22:52:11.193" Score="13" Body="&lt;p&gt;The Russians brought some new ideas to the missile warfare when they mated the Vympel R-73 with Mig-29. The most important of these was the high offset sensor lock mode, which allowed the pilot to 'lock on' to the targer regardless of where the nose was pointed at. &lt;a href=&quot;http://www.airspacemag.com/military-aviation/truth-about-mig-29-180952403/?page=3&quot; rel=&quot;noreferrer&quot;&gt;According to Peter “Stoini” Steiniger&lt;/a&gt; a JG 73 Pilot, who flew Mig-29s in East Germany,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The nice airframe in combination with one weapon was the killer: The Archer in [sensor lock] mode.” Introduced in the mid-1980s, the Archer AA-11 is a very capable heat-seeker with a greater range than the U.S. Sidewinder. “A simple monocular lens in front of my right eye enabled me to slew the seeker head of the missile onto my adversary at high angle off [target].” The Fulcrum’s ability to lock a missile even though its nose was pointed far away from its target “watered many eyes,” ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The image below shows the missile aiming sight mounted on the helmet of a JG 73 pilot.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RFBjJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RFBjJ.jpg&quot; alt=&quot;missile aiming&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airspacemag.com/military-aviation/truth-about-mig-29-180952403/?page=1&quot; rel=&quot;noreferrer&quot;&gt;airspacemag.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;This off boresignt advantage was not achieved by the western forces till they introduced the AIM-9X missile and the Joint Helmet-mounted Cueing System in 2002.&lt;/p&gt;&#xA;&lt;p&gt;Aircraft-wise, the Mig-29 was a revelation to the west as the previous Russian designs have not been so sophisticated, so as to speak. The West was concerned enough with Mig-29 to start looking for new fighter ideas. Another important equipment in Mig-29 was the Infra Red Search and Track System (IRSTS), an idea for which the US is just warming up. Most of the &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/how-to-win-in-a-dogfight-stories-from-a-pilot-who-flew-1682723379&quot; rel=&quot;noreferrer&quot;&gt;exchange pilots, who flew the Mig-29 against the US F-15s and 16s&lt;/a&gt; were quite surprised and initial engagements usually went the 29s way, though techniques were later devloped exploting the Mig-29s' weaknesses. From an &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/how-to-win-in-a-dogfight-stories-from-a-pilot-who-flew-1682723379&quot; rel=&quot;noreferrer&quot;&gt;USAF exchange pilot&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;From BVR (beyond visual range), the MiG-29 is totally outclassed by western fighters. Lack of situation awareness and the short range of the AA-10A missile compared to the AMRAAM means the NATO fighter is going to have to be having a really bad day for the Fulcrum pilot to be successful.&lt;/p&gt;&#xA;&lt;p&gt;In the WVR (within visual range) arena, a skilled MiG-29 pilot can give an [F-15] Eagle or [F-16] Viper driver all he/she wants.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-06-15T20:26:45.720" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="25237" PostTypeId="1" AcceptedAnswerId="25258" CreationDate="2016-02-15T01:06:12.390" Score="11" ViewCount="3840" Body="&lt;p&gt;At a gate in Denver Int'l there is a United plane with 2 jetbridges. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/QYgz8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QYgz8.png&quot; alt=&quot;united777&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do some airports have to put 2 jetbridges on a plane? Is it necessary?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-18T21:40:12.557" LastActivityDate="2016-02-18T21:40:12.557" Title="Why do some airports have to put 2 jetbridges on one aircraft?" Tags="&lt;commercial-aviation&gt;&lt;airline-operations&gt;&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25238" PostTypeId="2" ParentId="25237" CreationDate="2016-02-15T01:12:26.400" Score="8" Body="&lt;p&gt;The reason they use 2 or sometimes even 3 (A380) for wide-body aircraft (I have seen 2 on a B757, but that is rare) is because the more entrances to facilitate faster boarding and unloading passengers from the airplane. It saves much more time than loading the plane from one jetbridge and in the case of the A380, there are 2 full wide-body decks to fill. Passengers also like getting on and getting off the plane quicker as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interesting that there is &lt;a href=&quot;https://travel.stackexchange.com/questions/20098/how-many-jetways-are-used-when-boarding-a-boeing-777-in-sfo&quot;&gt;this&lt;/a&gt; similar question on travel.se&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:52:13.407" LastActivityDate="2016-02-15T01:22:04.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25239" PostTypeId="2" ParentId="25237" CreationDate="2016-02-15T01:14:38.140" Score="17" Body="&lt;p&gt;It is not strictly necessary. But it is done in order to save time. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;More points of passenger loading leads to faster loading, potentially reducing delays, airport charges etc.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In some cases, there is a seperate jet bridge for first/business class.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For large aircraft like A380 etc, is quite common to use multiple jet bridges as use of a single one may lead to quite large loading time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-15T01:14:38.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25240" PostTypeId="1" AcceptedAnswerId="25242" CreationDate="2016-02-15T01:49:15.993" Score="5" ViewCount="2349" Body="&lt;p&gt;As you can see in the airport diagram the runways are very separated from the terminals:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Dmh9e.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dmh9e.png&quot; alt=&quot;denverint&amp;#39;l&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've  found a similar &lt;a href=&quot;https://aviation.stackexchange.com/questions/9500/why-does-schiphol-airport-have-such-a-long-taxi/9501#9501&quot;&gt;question&lt;/a&gt; about Schiphol runways and one of them is very separated because of the noise. But at Denver Airport there are no towns or cities near the runways so, what could be the reason?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/nextgen/snapshots/airport/?locationId=26&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-05T17:11:45.370" Title="Why are the runways on Denver Int'l very separated from the terminals?" Tags="&lt;runways&gt;&lt;airport-design&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25241" PostTypeId="2" ParentId="25237" CreationDate="2016-02-15T02:08:40.217" Score="6" Body="&lt;p&gt;In addition to Aeroalias' answer, some airports adopt a Multi Aircraft(Apron) Ramp System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gate may be used by multiple small or a single large aircraft. It allows airport planners to make their gates more flexible and efficient. In such a case two or more jet bridges are needed for a single gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of the busiest airports including Beijing Capital, London Heathrow and New York JFK have already adopted such a system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More details can see this &lt;a href=&quot;http://www.airportsinternational.com/2013/02/manoeuvres-on-mars/13873&quot; rel=&quot;nofollow&quot;&gt;article&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="9276" LastEditDate="2016-02-15T12:58:24.113" LastActivityDate="2016-02-15T12:58:24.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25242" PostTypeId="2" ParentId="25240" CreationDate="2016-02-15T02:24:05.440" Score="6" Body="&lt;p&gt;FAA has published &lt;a href=&quot;https://www.google.co.uk/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwijrryt5fjKAhUrOJoKHUHOAFsQFggmMAE&amp;amp;url=http%3A%2F%2Fwww.flydenver.com%2Fsites%2Fdefault%2Ffiles%2Fmasterplan%2FmasterPlanBrochure.pdf&amp;amp;usg=AFQjCNE-nWHHOVKT13fO-j1IyLNSCCp3Kw&amp;amp;sig2=UQYwY54VOPV1I8go3zKyZg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advisory Circular 150/5300-13A&lt;/a&gt;, Airport Design, which includes recommendations for parallel runway separation for US airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It summarises:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Quadruple simultaneous precision instrument approaches are currently&#xA;  under study by the FAA. In the interim, the FAA, on a case-by-case&#xA;  basis, will consider proposals utilizing separations down to a minimum&#xA;  of 5,000 feet (1524 m). Quadruples may require special radar,&#xA;  monitoring equipment, etc. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Simultaneous non-radar departures require a parallel runway centerline&#xA;  separation of at least 3,500 feet (1067 m), and Simultaneous radar&#xA;  departures at least 2,500 feet (762 m).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Back to the case, Denver airport is one of the busiest airports in terms of aircraft movements. It needs 6+ runways to support 550K aircraft movements every year. However, the more runways an airport has, the higher the chance air routes will interfere with each other. More separation between runways (and thus the terminals) can reduced distributions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact the &lt;a href=&quot;https://www.google.co.uk/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=2&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwijrryt5fjKAhUrOJoKHUHOAFsQFggmMAE&amp;amp;url=http%3A%2F%2Fwww.flydenver.com%2Fsites%2Fdefault%2Ffiles%2Fmasterplan%2FmasterPlanBrochure.pdf&amp;amp;usg=AFQjCNE-nWHHOVKT13fO-j1IyLNSCCp3Kw&amp;amp;sig2=UQYwY54VOPV1I8go3zKyZg&quot; rel=&quot;nofollow noreferrer&quot;&gt;airport masterplan (PDF)&lt;/a&gt; shows that the operator is planning to build runways further separated from the terminals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS1: Denver is not the only case. Many mega airports have been built or are planned to be built with runways far from the terminal buildings, including &lt;a href=&quot;https://www.google.co.uk/maps?q=Dallas/Fort%20worth&amp;amp;biw=1366&amp;amp;bih=667&amp;amp;bav=on.2,or.r_cp.&amp;amp;bvm=bv.114195076,d.bGs&amp;amp;um=1&amp;amp;ie=UTF-8&amp;amp;sa=X&amp;amp;ved=0ahUKEwil0viD6PjKAhXFAJoKHfhaCxgQ_AUIBigB&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dallas/Fort Worth&lt;/a&gt;, &lt;a href=&quot;https://www.google.co.uk/maps/@38.944308,-77.4544185,3122m/data=!3m1!1e3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Washington Dulles&lt;/a&gt;, &lt;a href=&quot;https://www.google.co.uk/maps/@29.9818262,-95.3424445,9268m/data=!3m1!1e3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Houston George Bush&lt;/a&gt;, as well as &lt;a href=&quot;http://images.adsttc.com/media/images/550a/7fd3/e58e/ceb2/7000/00cc/large_jpg/1-light-box---general-day-shot-1_(1).jpg?1426751422&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dubai Al Maktoum Airport&lt;/a&gt;, &lt;a href=&quot;http://www.adp-i.com/sites/default/files/styles/xlarge/public/seoul_incheon_-_coree_du_sud.jpg?itok=c8Lv1nLF&quot; rel=&quot;nofollow noreferrer&quot;&gt;Seoul Incheon airport&lt;/a&gt; and &lt;a href=&quot;http://a3.att.hudong.com/61/11/01300000466621125752112189853.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Shanghai Pudong airport&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS2: Even though built in less populated area, Denver airport still have noise issues. More details can be seen &lt;a href=&quot;https://aviation.stackexchange.com/questions/20815/why-is-denver-international-airport-runway-16r-34l-rarely-used&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.flydenver.com/sites/default/files/rules/210_noise.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;there&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-02-15T10:52:18.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25245" PostTypeId="1" AcceptedAnswerId="27906" CreationDate="2016-02-15T07:53:53.317" Score="5" ViewCount="746" Body="&lt;p&gt;Sparked by &lt;a href=&quot;https://aviation.stackexchange.com/q/25217/3248&quot;&gt;this question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take any non-propeller powered aircraft, when idle, the sound produced by the engines are fairly low pitched, and as the engine spins up, increasing in pitch before becoming a full on roar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I figured that the major sources of engine noise could be &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The air rushing out of the exhaust,&lt;/li&gt;&#xA;&lt;li&gt;The noise of combustion in the engine, &lt;/li&gt;&#xA;&lt;li&gt;The mechanical noise of engine parts&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;My question is what causes the majority of the engine noise at idle vs full power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To stop this question being too broad, lets discount noise coming from any source that's not the engine's of the aircraft in question. I just want to know about engine noise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had a look at &lt;a href=&quot;https://aviation.stackexchange.com/q/23176/3248&quot;&gt;this question&lt;/a&gt;, but that doesn't have any information about the source of engine noise, just that the turbine itself will also produce noise which is something I didn't consider.&lt;/p&gt;&#xA;" OwnerUserId="3248" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-05-30T22:28:06.033" Title="What is the major source of engine noise for non-propeller aircraft?" Tags="&lt;jet-engine&gt;&lt;noise&gt;&lt;turbofan&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25248" PostTypeId="1" AcceptedAnswerId="25249" CreationDate="2016-02-15T12:20:42.630" Score="0" ViewCount="207" Body="&lt;p&gt;Is it possible to prevent/avoid laser beams with new technologies on windscreem?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-02-15T12:42:39.137" Title="Windshield to prevent laser strikes" Tags="&lt;windows&gt;&lt;laser-illumination&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-02-15T14:41:39.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="25249" PostTypeId="2" ParentId="25248" CreationDate="2016-02-15T12:42:39.137" Score="3" Body="&lt;p&gt;Only if you know the laser wavelength.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the windshield uses a color filter, it can attenuate the light intensity at one wavelength while being transparent for other wavelengths, so the pilot can still see what is going on outside. The colors will look strange, but laser beams of the filter wavelength would have less intensity when viewed through this screen. This only works, however, if the laser wavelength is known beforehand, so the right filter can be used. All other light signals, approach lights and what not would need to use sufficiently different wavelengths so they are still visible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think of an approach in fog, rain or haze. Sometimes all the pilot sees is a faint glow - if the filter takes this away, the pilot will notice the lights only later, when they are closer and there is less time to react.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other alternative is &lt;a href=&quot;https://en.wikipedia.org/wiki/Synthetic_vision_system&quot; rel=&quot;nofollow&quot;&gt;synthetic vision&lt;/a&gt;. The cockpit has a row of screens which show the images of cameras in the nose of the aircraft. This was already investigated by NASA for supersonic passenger aircraft, but met resistance from pilots. The reduced contrast of screens will make lasers merely a nuisance, but not harm the pilot. Clever software could even filter out too bright light sources.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-15T12:42:39.137" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25250" PostTypeId="1" AcceptedAnswerId="25256" CreationDate="2016-02-15T13:01:35.157" Score="42" ViewCount="26812" Body="&lt;p&gt;Many fighter jets have double vertical stabilizers, e.g. F-14, F-15, F/A-18, F-22:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eASrU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eASrU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the contrary, most general aviation planes and commercial airliners do not. While there are certainly exceptions in both categories, I think it is fair to say that this design is, comparatively, far more common in fighter jets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the advantage of double vertical stabilizers? Why is it common in fighter jets?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="1467" LastEditDate="2017-12-05T12:59:23.390" LastActivityDate="2020-03-18T22:03:12.290" Title="Why do many fighter jets have double vertical stabilizers?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;jet&gt;&lt;fighter&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25251" PostTypeId="5" CreationDate="2016-02-15T13:04:27.100" Score="0" Body="" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-15T13:04:27.100" LastActivityDate="2016-02-15T13:04:27.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25252" PostTypeId="4" CreationDate="2016-02-15T13:04:27.100" Score="0" Body="Questions about usage of mechanical brakes on the wheels for slowing down." OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-15T13:04:27.100" LastActivityDate="2016-02-15T13:04:27.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25253" PostTypeId="5" CreationDate="2016-02-15T13:08:04.467" Score="0" Body="" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-15T13:08:04.467" LastActivityDate="2016-02-15T13:08:04.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25254" PostTypeId="4" CreationDate="2016-02-15T13:08:04.467" Score="0" Body="Examinations for acquiring or renewing pilot licenses." OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-15T13:08:04.467" LastActivityDate="2016-02-15T13:08:04.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25255" PostTypeId="2" ParentId="25250" CreationDate="2016-02-15T13:38:44.733" Score="30" Body="&lt;p&gt;There are a few reasons many fighter/bomber designs have 2 vertical stabilizers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;one large tail produced more shear force at the root, 2 smaller tails mean less force at the vertical stabilizer root. This allows for a lighter structure&lt;/li&gt;&#xA;&lt;li&gt;redundancy if one tail is damaged. The US navy philosophy is 2 is better than one, this makes sense given that its aircraft spend much of the time over oceans where there's few alternative landing sites&lt;/li&gt;&#xA;&lt;li&gt;twin tails are shorter than one big tail, and vertical height is a consideration on carrier aircraft&lt;/li&gt;&#xA;&lt;li&gt;twin engines spaced apart make for a wide fuselage back which can create a blanking effect with a single tail in the middle, 2 tails mean that there's always one vertical stabilizer that is effective&lt;/li&gt;&#xA;&lt;li&gt;Twin tails create less of a radar cross section, and allow the tails to be angled to deflect radar signals away from airborne radar sources&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2016-02-15T14:43:58.913" LastActivityDate="2016-02-15T14:43:58.913" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="25256" PostTypeId="2" ParentId="25250" CreationDate="2016-02-15T13:56:47.917" Score="29" Body="&lt;p&gt;Though the reasons for having twin vertical stabilizers vary from aircraft to aircraft and is mainly a design decision, there are some advantages in having twin vertical stabilizers. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Having twin rudders increases the redundancy, which is important for combat aircraft in case of battle damage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Having twin vertical stabilizers helps in reduction in height, though this is mainly an issue with naval aircraft. As an example, both the S-3 Viking and A-5 Vigilante had to fold their vertical tails for fitting inside hangars.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2k6L9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2k6L9.jpg&quot; alt=&quot;A-5&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By USN - www.navsource.org &lt;a href=&quot;https://i.stack.imgur.com/2k6L9.jpg&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt;, Public Domain, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=3109863&quot; rel=&quot;noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=3109863&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In case of twin engined aircraft with engines spaced wide apart, having twin rudders helps in getting sufficient rudder authority in case of an engine failure. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Having twin vertical stabilizers reduces their size, resulting in reduced stress at stabilizer root and reduction in weight. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One advantage of having twin vertical stabilizers is that the location of vertical tails helps in having control authority at high alpha (where the fuselage/wing can blank a single vertical stabilizer).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In modern stealth aircraft, having a twin tail enables them to be canted, helping in reducing RCS. Except for tailless aircraft (like B-2), almost all other stealth aircraft have canted twin tails.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some aircraft, like A-10 had twin tails that were designed to mask engine exhaust from ground to ensure better survivability.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the end of the day, having a single or twin vertical tail is a design decision and is taken based on the requirements. For example, preliminary designs of the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_A-5_Vigilante&quot; rel=&quot;noreferrer&quot;&gt;A-5 Vigilante&lt;/a&gt; had twin tails, while the final design had a single tail, while it was the other way in case of &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_F-14_Tomcat&quot; rel=&quot;noreferrer&quot;&gt;F-14 Tomcat&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-15T13:56:47.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25257" PostTypeId="1" AcceptedAnswerId="39275" CreationDate="2016-02-15T14:39:57.953" Score="3" ViewCount="888" Body="&lt;p&gt;I am having trouble finding the established results of inviscid flow CL and Cd variation over NACA 0012 airfoil, for the transonic region. I need the data to verify the results I am getting through my CFD simulations. I have recently started learning CFD and the actual results would be really useful to me as they would clarify whether I am in the right direction or not. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Please suggest any site, research paper or book.&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="19" LastEditDate="2016-07-28T13:14:14.450" LastActivityDate="2017-06-26T05:12:21.873" Title="Are there any reference values for Cl and Cd of a NACA 0012 airfoil to verify CFD simulations?" Tags="&lt;aerodynamics&gt;&lt;airfoil&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25258" PostTypeId="2" ParentId="25237" CreationDate="2016-02-15T15:09:44.163" Score="6" Body="&lt;p&gt;So that economy class passengers can also see at least one of the higher classes (when they exit) and wish they booked that!  :-/ Trust me you sure will wish that and that someday can mean more &lt;code&gt;$&lt;/code&gt; for the airline &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8uOpc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8uOpc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: Original picture was taken from this very question&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Joking aside I have seen it happen on many airlines. The people on left Aisle go out from the first one and people on the right aisle take the longer route to exit from the gate that's closer to cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Primary reason must be to transfer people faster to make the jet available for crew as soon as possible specially after a landing when the jet has to fly again in an hour.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="1048" LastEditDate="2016-02-16T07:05:33.433" LastActivityDate="2016-02-16T07:05:33.433" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25260" PostTypeId="1" AcceptedAnswerId="31777" CreationDate="2016-02-15T15:26:10.393" Score="8" ViewCount="2230" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8986/can-a-passenger-realistically-replace-suddenly-incapacitated-pilots&quot;&gt;This question&lt;/a&gt; deals with the plausibility of the Hollywood cliché of a passenger on a commercial jetliner landing a passenger plane.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is related but broader, and less hypothetical:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has anyone ever found themselves in an emergency with no piloting experience (e.g., the amateur pilot of a small plane dies or is incapacitated, and the only other person in the plane has never flown anything before) and been talked down by Air Traffic Control?&lt;/p&gt;&#xA;" OwnerUserId="9888" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2019-01-12T04:23:47.087" Title="Has Air Traffic Control ever had to talk a first time pilot through a landing due to an emergency?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;emergency&gt;&lt;pilots&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25261" PostTypeId="1" CreationDate="2016-02-15T15:56:57.560" Score="4" ViewCount="683" Body="&lt;p&gt;Reading &lt;em&gt;[Long Range Aircraft-AEA Requirements]&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In appendix, Para 1.2 &lt;strong&gt;Definitions and specifications&lt;/strong&gt;, the definition for &quot;Payload&quot; states&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Payload should be the Volume Limited Payload (...) or the Maximum Zero Fuel Weight limited payload, whichever is the lesser.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How can we can define and understand &quot;Maximum Zero Fuel Weight limited payload&quot;?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="12220" LastEditDate="2016-02-28T22:34:21.853" LastActivityDate="2016-02-28T22:49:00.957" Title="What is the difference between a volume-limited-payload and a maximum-zero-fuel-weight-limited-payload?" Tags="&lt;commercial-aviation&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25262" PostTypeId="1" AcceptedAnswerId="25263" CreationDate="2016-02-15T16:47:59.780" Score="15" ViewCount="8706" Body="&lt;p&gt;Instrument approach charts list the equipment required to fly them in their name. For this example let's say we have an ILS or LOC/DME 36R approach. This approach requires an ILS receiver for the ILS portion, or both a LOC and DME receiver for the localizer only portion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's also say we're flying an airplane that has an inoperative glideslope receiver and is otherwise /G equipped with an IFR-certified and up-to-date GPS. Can the GPS be used in lieu of DME in this case?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="487" LastEditDate="2016-02-15T21:24:58.543" LastActivityDate="2016-08-23T15:56:27.223" Title="Can GPS be used in lieu of DME for instrument approaches?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;gnss&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25263" PostTypeId="2" ParentId="25262" CreationDate="2016-02-15T17:38:45.137" Score="16" Body="&lt;p&gt;Yes, the details are in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/90-108.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AC 90-108&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;7. Usage of Suitable RNAV Systems.&lt;/strong&gt; Subject to the operating requirements in this AC,operators may use a suitable RNAV system in&#xA;  the following ways.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;(1)&lt;/strong&gt; &lt;em&gt;Determine aircraft position relative to or distance from&lt;/em&gt; a VOR (see first note in subparagraph 7b), TACAN, NDB, compass locator&#xA;  (see second note in subparagraph 7b), DME fix; or a named fix defined&#xA;  by a VOR radial, TACAN course, NDB bearing, or compass locator bearing&#xA;  intersecting a VOR or Localizer (LOC) course&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And all fixes, procedures etc. must be loaded from the GPS database, you can't enter any fixes yourself based on lat/long or whatever (section 9(c)(1)).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-08-23T15:56:27.223" LastActivityDate="2016-08-23T15:56:27.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25264" PostTypeId="2" ParentId="25262" CreationDate="2016-02-15T17:38:48.363" Score="5" Body="&lt;p&gt;The short answer is, &quot;Yes, GPS can substitute for DME&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer answer, splitting some very fine hairs, is that they are not exactly the same thing, and you should at least be vaguely aware of the differences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DME literally &lt;em&gt;measures distance&lt;/em&gt;, by measuring how long a signal takes to make the round-trip.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS only knows the position of the receiver and the position of the fix in the database, and just &lt;em&gt;calculates the distance&lt;/em&gt; between.  That means that GPS is using trigonometry and math to calculate the distance between two points on an idealized sphere, while DME is also accounting for slant-distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IF the location of the target fix is affected by slant-distance or by some peculiarity of terrain, there may be a tiny discrepancy between DME's measured actual distance and GPS's calculated distance.   But in practice this difference is always going to be extremely small.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-02-15T17:38:48.363" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25265" PostTypeId="1" CreationDate="2016-02-15T17:47:23.050" Score="2" ViewCount="977" Body="&lt;p&gt;Fuel conservation programs are leading to single engine taxi out, asking the crew to start the other engine near or on the position 2, where the ground crew cannot monitor the engine's status outside the aircraft.&#xA;How safe is this procedure? One example is the jet pipe fire during the start up.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="12207" LastEditDate="2016-02-17T11:46:57.107" LastActivityDate="2016-03-18T12:36:38.857" Title="How safe is the single engine taxi out for twin engine aircraft?" Tags="&lt;engine&gt;&lt;taxiing&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25266" PostTypeId="2" ParentId="14944" CreationDate="2016-02-15T18:08:37.753" Score="0" Body="&lt;p&gt;Turbo props are better for lower speeds. The blades are that size because it also has to pulled along at the same speed as passenger aircraft. Turbo fans would ingest too much debris on landing on non prepared air fields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This thing can fly at 110kts to refuel helicopters and as fast as a passenger aircraft. It's civil registered so it can fly along civilian airways too. Carries more, flys slower, flys faster, higher and longer than any competition. It's also European so if you are European too......be very proud of what Airbus has acheieved.&lt;/p&gt;&#xA;" OwnerUserId="13526" LastActivityDate="2016-02-15T18:08:37.753" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25267" PostTypeId="1" AcceptedAnswerId="25269" CreationDate="2016-02-15T18:12:29.623" Score="0" ViewCount="545" Body="&lt;p&gt;In this &lt;a href=&quot;https://www.youtube.com/watch?v=nA3_EjuWDrY&quot; rel=&quot;nofollow noreferrer&quot;&gt;video&lt;/a&gt; when the aircraft is turning left(2:25) the spoilers on the wing move. What causes them to move? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3STye.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3STye.png&quot; alt=&quot;a320 tunisair&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-02-15T19:08:33.357" Title="Why do the spoilers move in this video?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-02-15T18:46:48.710" ContentLicense="CC BY-SA 3.0" />
  <row Id="25268" PostTypeId="2" ParentId="25267" CreationDate="2016-02-15T18:26:31.010" Score="-4" Body="&lt;p&gt;That is controlled by the pilot (indirectly via the computer system) who uses the spoiler to control the turn of the airplane instead of ailerons. Notice that the airplane turns when the spoilers move. It does so by killing the lift on one side by &quot;spoiling&quot; the airflow while the lift on the other wing creates the roll and bank moment with the &quot;unspoiled&quot; lift.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-02-15T19:08:33.357" LastActivityDate="2016-02-15T19:08:33.357" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25269" PostTypeId="2" ParentId="25267" CreationDate="2016-02-15T18:29:11.677" Score="4" Body="&lt;p&gt;Two reasons that are really one reason. In short: Because lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case though, it's &quot;to get rid of lift&quot;. The spoiler's job is to reduce the amount of lift the wing experiences. This can be done symmetrically, on both wings at the same time, to increase the rate of descent or keep an aircraft from lifting back off the ground when in ground effect, or in this case, it can be done asymmetrically, or only on one wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to turn, an aircraft has to create an imbalance of force, more on the side outside the turn, less on the inside of the turn. The wing to the inside of the turn needs to drop, but it doesn't really want to...it has lots of air pushing it up (when it doesn't, you will have a very bad day)!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The spoiler in this case is just acting as an extension of the aileron. By moving upward with the aileron itself, it spoils the airflow over the top of the wing a bit, reducing the lift, and causing the wing to drop a bit, raising the other wing. It also acts as a larger surface area for the incident airflow to impart force on, which also pushes the wing down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other side, the aileron is doing the opposite, increasing the wing's effective camber, at least near the tip, and increasing lift. Flaps do the same, but also are usually used symmetrically to increase lift on both wings. In some airplanes, you can have a 'flaperon', which can also be used as an additional control surface while also doing it's flap-thing.&lt;/p&gt;&#xA;" OwnerUserId="13527" LastActivityDate="2016-02-15T18:29:11.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25271" PostTypeId="2" ParentId="1601" CreationDate="2016-02-15T19:44:39.307" Score="5" Body="&lt;p&gt;Yes, the FAA issued a Letter of Interpretation from their Chief Counsel in May 2015 which covers &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2015/hoy%20-%20(2015)%20legal%20interpretation.pdf&quot; rel=&quot;noreferrer&quot;&gt;Section 61.58 proficiency checks&lt;/a&gt; and specifically addresses this issue. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It says that a pilot &lt;strong&gt;may&lt;/strong&gt; continue to act as PIC during the grace month under Parts 91, 121, and 135.  It says (in part, and emphasis added by me):&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Section 61.58(i) states that, if a pilot completes the proficiency&#xA;  check in the calendar month before or the calendar month after the&#xA;  month it is due, &quot;the pilot is considered to have taken it in the&#xA;  month in which it was due for the purpose of computing when the next&#xA;  pilot-incommand proficiency check is due.&quot; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;You have asked whether the language in paragraph (i) creates a &quot;grace&#xA;  month&quot; during which a pilot whose currency has lapsed under paragraph&#xA;  (a) may continue to act as pilot in command. The FAA has previously&#xA;  stated in a legal interpretation that § 61.58 includes a &quot;grace month&quot;&#xA;  for purposes of complying with the 12- and 24-month proficiency check&#xA;  requirements. We did not explicitly state, however, that a pilot may&#xA;  continue to act as PIC during this grace month. Legal Interpretation&#xA;  to Sean Conlin (Feb. 24, 2000). We have indicated, however, that&#xA;  similar provisions in parts 121 and 135 create a &quot;grace month&quot; during&#xA;  which a pilot may to continue to act as PIC during the month after the&#xA;  pilot's currency has lapsed? Legal Interpretation to Gregory S. Winton&#xA;  (2006), Legal Interpretation to J. Dennis Vanatta (June 25, 1996). &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;The FAA intended the grace month to limit disruptions in operations&#xA;  conducted under parts 121 and 135 by accommodating pilots who are&#xA;  unable to complete recurrent training requirements in the month they&#xA;  are due.&lt;/strong&gt; At the same time, the FAA did not want operators to use the&#xA;  grace month as a means of regularly extending a 12-month proficiency&#xA;  check to a 13-month proficiency check. For that reason, a proficiency&#xA;  check under part 121 or part 135 that is completed in the grace month&#xA;  is considered to be completed in the month it is due. The FAA believes&#xA;  that the same approach is appropriate for§ 61.58 proficiency checks.&#xA;  &lt;strong&gt;As such, a pilot may continue to act as pilot in command during the&#xA;  month after a§ 61.58 proficiency check is due.&lt;/strong&gt; However, when a pilot&#xA;  completes a §61.58 proficiency check during this grace month, it is&#xA;  considered to have been completed during the month it was due for the&#xA;  purpose of calculating the next proficiency check.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-02-15T19:44:39.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25275" PostTypeId="1" CreationDate="2016-02-15T22:29:19.267" Score="8" ViewCount="17882" Body="&lt;p&gt;Every time I have flown and filed flight plans the CFI or the person I have rented the plane from has told me what equipment code to put on the flight plan. I am curious how you would figure out on your own. Is it in the POH?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-02-16T00:06:13.580" Title="How do you know what equipment code to put on a flight plan?" Tags="&lt;equipment&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25277" PostTypeId="2" ParentId="25275" CreationDate="2016-02-16T00:06:13.580" Score="7" Body="&lt;p&gt;Basically you know what equipment is installed on the aircraft (and in working order), and that's what you enter on the form.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For FAA flight plans, there's a list &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;noreferrer&quot;&gt;in the AIM&lt;/a&gt; (It's table 5-1-3).&lt;br&gt;&#xA;Generally for domestic flight plans you file the &quot;best&quot; equipment you have onboard in working order.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA &quot;Domestic&quot; flight plans are eventually going away though, and we'll be expected to use the ICAO flight plan format (including its equipment codes).&lt;br&gt;&#xA;ICAO equipment codes are a little more complicated because the &quot;Equipment&quot; box lets you list a whole lot more stuff (and the more you enter the more ATC knows in the event of an emergency): Basically you list all the equipment you have in working order under the equipment box on the ICAO flight plan form.&lt;br&gt;&#xA;Lists of ICAO equipment codes is available (the one &lt;a href=&quot;https://en.wikipedia.org/wiki/Equipment_codes&quot; rel=&quot;noreferrer&quot;&gt;on Wikipedia&lt;/a&gt; is pretty complete), and there are &lt;a href=&quot;http://www.rocketroute.com/ICAO2012-PBN-RNAV.php&quot; rel=&quot;noreferrer&quot;&gt;handy wizards floating around&lt;/a&gt; that let you check boxes and get the string you need to enter on the flight plan.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Look at two hypothetical aircraft, both identical Cessna 172s with different equipment to see how it works:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aircraft #1&lt;/strong&gt; has a VHF Nav/Com (VOR only, no ILS), DME, GPS, and Mode C transponder.&lt;br&gt;&#xA;This aircraft would file &lt;code&gt;/G&lt;/code&gt; on a domestic flight plan, and &lt;code&gt;DGOV/C&lt;/code&gt; on an ICAO flight plan (the ICAO flight plan may also include &lt;code&gt;R&lt;/code&gt; and an appropriate &lt;code&gt;PBN&lt;/code&gt; code for the GPS capability).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aircraft #2&lt;/strong&gt; has a VHF Nav/Com with ILS capability, and a Mode C transponder.&lt;br&gt;&#xA;This aircraft would file &lt;code&gt;/U&lt;/code&gt; on a domestic flight plan, and &lt;code&gt;SV/C&lt;/code&gt; on an ICAO flight plan.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that the ICAO flight plan gives ATC more information to work with:&lt;br&gt;&#xA;If Aircraft #1 calls up and says their GPS died ATC knows they can assign them clearances that use VORs and DME for navigation, but that the aircraft cannot accept an ILS approach at their destination.&lt;br&gt;&#xA;Conversely if working off a domestic flight plan ATC will have to ask the pilot what their navigation capabilities are (or they may assume &quot;standard&quot; equipment including an glideslope receiver and ILS capability and offer the pilot an ILS approach only to be told &quot;Unable ILS&quot; by the pilot).&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-02-16T00:06:13.580" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25278" PostTypeId="2" ParentId="25136" CreationDate="2016-02-16T01:25:27.627" Score="6" Body="&lt;p&gt;Aircraft stabilizers (both vertical and horizontal) usually have metallic leading edges without paint or anti-erosion paint system. This can be seen in the following figure for Airbus A320 family.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vZY4l.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vZY4l.jpg&quot; alt=&quot;paint&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://lms.aeroflot.ru/data/Part145/Structure_Reapair/Paint%20system.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus Structure Training Manual&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft with composite stabilizers, leading edge erosion is arrested by bonding metal to the leading edge, or making the &lt;a href=&quot;http://old.seattletimes.com/html/boeingaerospace/2003612251_boeing111.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;leading edge using metal, as in 787&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The .. leading edge assembly, ..., with an aluminum edge and a fiberglass and paper-honeycomb skin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In such cases, (as @Todd points out), the leading edge is usually left unpainted in order to prevent paint erosion. This method is used in the leading edge of the main rotor blades of a number of helicopters. In such cases, either the bare metal is left as is or a protective film is used to combat erosion.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-16T01:25:27.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25279" PostTypeId="1" AcceptedAnswerId="25286" CreationDate="2016-02-16T02:12:52.803" Score="3" ViewCount="1862" Body="&lt;p&gt;According to &lt;a href=&quot;https://aviation.stackexchange.com/questions/24615/why-do-some-airlines-not-use-containers-for-luggage&quot;&gt;this question&lt;/a&gt; especially smaller airlines often don't use ULD in the cargo hold. But wouldn't that be dangerous for the stability of the aircraft? Won't the cargo move and unbalance the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-16T12:06:43.683" Title="How is stability ensured with bulk-loaded cargo?" Tags="&lt;airline-operations&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25280" PostTypeId="1" CreationDate="2016-02-16T05:38:10.213" Score="0" ViewCount="1312" Body="&lt;p&gt;If a tail dragger airplane is converted to one with conventional tricycle landing gears, how will this affect the balance of the airplane? It is possible to offset the effect by shifting weights around the airframe?&lt;/p&gt;&#xA;" OwnerUserId="13536" LastEditorUserId="3394" LastEditDate="2016-02-16T15:33:23.320" LastActivityDate="2016-02-17T16:01:00.337" Title="If a tail dragger is converted to a tricycle gear airplane, what will be the effect on weight distribution?" Tags="&lt;landing-gear&gt;&lt;weight-and-balance&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25281" PostTypeId="1" CreationDate="2016-02-16T08:10:27.653" Score="11" ViewCount="1428" Body="&lt;p&gt;For the same total energy and power output would a battery powered vehicle be lighter than one which uses a fuel burning engine (Currently)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is intended for helicopters.&lt;/p&gt;&#xA;" OwnerUserId="13325" LastEditorUserId="19" LastEditDate="2016-07-14T08:17:14.423" LastActivityDate="2016-07-15T18:07:54.457" Title="How does the energy and weight efficiency compare between a battery/electrical propulsion and combustion engine?" Tags="&lt;helicopter&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25282" PostTypeId="2" ParentId="25281" CreationDate="2016-02-16T09:17:32.137" Score="12" Body="&lt;p&gt;Poorly. That is a reason why we don't see battery powered aircraft beyond some experiments. The specific power is still much worse for batteries.&lt;/p&gt;&#xA;&lt;h2&gt;Energy storage:&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jet fuel has specific energy around 43 MJ/kg and energy density around 35 GJ/m³&lt;sup&gt;[&lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_fuel#Typical_physical_properties_for_Jet_A_and_Jet_A-1&quot; rel=&quot;noreferrer&quot;&gt;1&lt;/a&gt;]&lt;/sup&gt;.&lt;/li&gt;&#xA;&lt;li&gt;The best mass-produced rechargeable batteries to this day, Lithium-ion polymer, the best kind has specific energy 0.95 MJ/kg and energy density at most 2.6 GJ/m³&lt;sup&gt;[&lt;a href=&quot;https://en.wikipedia.org/wiki/Lithium_polymer_battery&quot; rel=&quot;noreferrer&quot;&gt;2&lt;/a&gt;]&lt;/sup&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;That is more than an order of magnitude difference in favour of hydrocarbon fuel (almost 2 orders by weight, one by volume). Even taking into account the 2-3 times higher efficiency of electric engines (which do not suffer the theoretical efficiency limits associated with heat engines) hydrocarbon fuel is an order of magnitude better by weight.&lt;/p&gt;&#xA;&lt;h2&gt;Engines:&lt;/h2&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;According to [&lt;a href=&quot;https://en.wikipedia.org/wiki/Power-to-weight_ratio&quot; rel=&quot;noreferrer&quot;&gt;3&lt;/a&gt;], the power-to-weight ratios for electric engines and gas turbines are comparable (in the range of 5-10 kW/kg).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Electric engine won't give any advantage to electricity.&lt;/p&gt;&#xA;&lt;p&gt;Well, the difference in energy density is so huge that even large difference in engine weight wouldn't help much anyway. For models, electricity is OK as due to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Square-cube_law&quot; rel=&quot;noreferrer&quot;&gt;square-cube law&lt;/a&gt; they have a lot of power and lift and small-scale heat engines are difficult. But for aircraft carrying humans, batteries are very far from usable.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-07-15T18:07:54.457" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25283" PostTypeId="1" AcceptedAnswerId="25285" CreationDate="2016-02-16T10:55:14.843" Score="13" ViewCount="3034" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14864/why-is-the-nacelle-outlet-of-the-tail-engine-of-the-l-1011-tristar-lower-than-th?rq=1&quot;&gt;This question&lt;/a&gt; asks about the S-duct of the L-1011 Tristar. &lt;a href=&quot;https://aviation.stackexchange.com/a/14867/4197&quot;&gt;Fooot's answer&lt;/a&gt; shows a cut-out of the L-1011. Looking at this cut-out, I'm wondering:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;If the engine is at the 'normal' location of the APU, where did the designers of the L-1011 put the APU?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;I did a search, and found &lt;a href=&quot;https://sites.google.com/site/thel1011projectwiki/aircraft-systems/auxiliary-power-unit-apu&quot; rel=&quot;nofollow noreferrer&quot;&gt;this site&lt;/a&gt; which mentions&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The APU is located in a compartment in the aft fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/72027&quot; rel=&quot;nofollow noreferrer&quot;&gt;Another site&lt;/a&gt; mentions&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Its still in the &amp;quot;tail&amp;quot;. Its mounted below the #2 engine. Just forward of the tail skid.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;But I don't see how you could fit the APU in the small available space.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2020-09-14T08:49:17.120" LastActivityDate="2020-09-14T08:49:17.120" Title="Where is the APU in the case of an S-duct (like the L-1011)?" Tags="&lt;aircraft-design&gt;&lt;apu&gt;&lt;lockheed-tristar&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25285" PostTypeId="2" ParentId="25283" CreationDate="2016-02-16T11:40:47.553" Score="10" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ovxyU.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ovxyU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://aircraft.wikia.com/wiki/Lockheed_L-1011_Tristar?file=Cutaway.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt; via aircraft.wikia.com)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;APU is number 134 on the cutaway, which you can find near root of left stabilator leading edge. It is ahead of the engine, below the intake duct, on the left side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GXzqk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GXzqk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;By Reedy (Own work) [&lt;a href=&quot;http://creativecommons.org/licenses/by-sa/3.0&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 3.0&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File%3ALockheed_L-1011_TriStar_N700TS%2C_National_Airline_History_Museum%2C_Kansas_2013-03-16_(105).jpg&quot; rel=&quot;noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its exhaust is on the right side close to the stabilator's leading edge.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="14897" LastEditDate="2017-05-03T23:17:39.010" LastActivityDate="2017-05-03T23:17:39.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25286" PostTypeId="2" ParentId="25279" CreationDate="2016-02-16T12:06:43.683" Score="0" Body="&lt;p&gt;You can simply tie down the cargo to prevent its movement. Most planes have nets that subdivide the bulk cargo compartment, so as to prevent movement of the baggage. For example, the following image shows the cargo hold of a B737 with dividers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Fdtzs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fdtzs.jpg&quot; alt=&quot;737 divider&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airport-data.com/aircraft/photo/000613735.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;airport-data.com&lt;/a&gt; Photographer:  Nick Taylor Photography&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.fly-car.de/local/media/formulare/airbusindustries.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ground operations manual&lt;/a&gt; of a carrier gives the following procedure for securing loads in A320:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1.1.4.2.1. Load Securing A321 (bulk loaded)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The divider and door net in each compartment must be closed at any time. Additional tie-down is normally not required except for individual items of load which by their nature, shape or density may constitute a hazard. They must be restrained, which can be achieved by filling the cargo hold or net&#xA;  section volumetrically, or by tie-down.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;... Packages weighing more than 150kg shall be restraint or individually tied-down. Single packages should be tied-down. Tie-down of loads to aircraft structure is achieved by straps or nets connected to the tie-&#xA;  down points located on the cargo hold floor. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-16T12:06:43.683" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25288" PostTypeId="2" ParentId="25231" CreationDate="2016-02-16T12:52:11.643" Score="1" Body="&lt;p&gt;Dew point can most certainly be used for performance. High humidity can cause a longer take off roll. &#xA;When combined with a high altitude airport and hot temps, it can be a struggle to get airborne. &#xA;Cooler, less humid air is more dense--there's more &quot;air&quot; for the wing to bite into. So, a pilot listening to ATIS would want to know the temp, dew point, and temp for the airport to determine (in this example) takeoff roll distance. &lt;/p&gt;&#xA;" OwnerUserId="13541" LastEditorUserId="13541" LastEditDate="2016-02-16T13:26:39.320" LastActivityDate="2016-02-16T13:26:39.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25289" PostTypeId="1" CreationDate="2016-02-16T13:31:58.393" Score="2" ViewCount="185" Body="&lt;p&gt;Has this been tried in aviation history?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To make airplane sea crashes easier to find, can we use a colored liquid that is lighter than water, environmentally-friendly and safe, with fluorescent properties so that if an airplane crashes into the ocean, this liquid would leak out and float to the surface. During the day, the color is noticeable by satellite and by night it glows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does something like this exist? Can it be easily implemented? Has it already been attempted?&lt;/p&gt;&#xA;" OwnerUserId="13544" LastActivityDate="2016-02-16T14:06:40.170" Title="Does it exist? Environmentally-friendly/safe fluorescent liquid to make sea crashes easier to find?" Tags="&lt;airliner&gt;&lt;search-and-rescue&gt;&lt;oceanic&gt;&lt;accident-investigation&gt;&lt;malaysia&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2016-02-16T15:30:16.430" ContentLicense="CC BY-SA 3.0" />
  <row Id="25290" PostTypeId="1" CreationDate="2016-02-16T13:33:15.123" Score="5" ViewCount="981" Body="&lt;p&gt;I am FAA certified, but my medical certificate has lapsed. Would my pilot certificates and a fresh medical enable me to fly in Japan?&lt;/p&gt;&#xA;" OwnerUserId="13541" LastEditorUserId="19" LastEditDate="2016-07-07T09:30:55.257" LastActivityDate="2019-09-20T14:02:25.380" Title="What certificates/medical are required to fly in Japan?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;general-aviation&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25291" PostTypeId="2" ParentId="25289" CreationDate="2016-02-16T14:06:40.170" Score="2" Body="&lt;p&gt;Thanks to those who commented and provided answer-worthy comments. Thanks!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is already in existance today:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@Andy &lt;a href=&quot;https://aviation.stackexchange.com/questions/25289/does-it-exist-environmentally-friendly-safe-fluorescent-liquid-to-make-sea-cras?noredirect=1#comment60601_25289&quot;&gt;commented&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For spacecraft splashdowns (certainly Gemini, maybe others) they used&#xA;  a green marker dye, but I don't know how long it lasted. That would be&#xA;  a good thing to start with as they must have tested how long the&#xA;  traces were visible when choosing it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;@RogerLipscombe &lt;a href=&quot;https://aviation.stackexchange.com/questions/25289/does-it-exist-environmentally-friendly-safe-fluorescent-liquid-to-make-sea-cras?noredirect=1#comment60602_25289&quot;&gt;commented&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;prestodye.com/sea-dye-markers says &quot;30 to 40 minutes&quot;, depending on&#xA;  sea conditions. Apparently there's a standard: MIL-S-17980D.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;And for the challenges:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@abelenky &lt;a href=&quot;https://aviation.stackexchange.com/questions/25289/does-it-exist-environmentally-friendly-safe-fluorescent-liquid-to-make-sea-cras?noredirect=1#comment60597_25289&quot;&gt;commented&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Rough approximation: How many gallons of this stuff would you need for&#xA;  it to not dissipate in minutes? How much would that weigh? How often&#xA;  to airplanes crash in the sea? The cost and complexity just doesn't&#xA;  even come close to the benefit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13544" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-02-16T14:06:40.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25292" PostTypeId="1" AcceptedAnswerId="25300" CreationDate="2016-02-16T14:14:46.097" Score="8" ViewCount="880" Body="&lt;p&gt;These last few weeks I have been flying a couple of different aircraft that had inoperative glideslope capabilities, but I was able to fly &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system_localizer&quot; rel=&quot;nofollow noreferrer&quot;&gt;LOC&lt;/a&gt; approaches without trouble. In my career as a pilot and mechanic, I have always had the—possibly inaccurate—understanding that a &lt;a href=&quot;http://www.avweb.com/news/avionics/183234-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;VHF NAV receiver&lt;/a&gt; had the capability of receiving and processing both &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR&lt;/a&gt; and LOC signals. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is prompted by &lt;a href=&quot;https://aviation.stackexchange.com/a/25277/12720&quot;&gt;this answer to a question regarding flight plan equipment codes&lt;/a&gt;—and particularly the comment section of that answer. In the comments of that answer it was stated that an ILS capable VHF NAV receiver is necessary to fly a LOC approach. For the purpose of this question let's overlook the inaccuracy of the &lt;em&gt;ILS&lt;/em&gt; part of that statement and instead consider the &lt;em&gt;LOC&lt;/em&gt; capabilities of a VHF NAV receiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the additional requirements needed for &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_landing_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS&lt;/a&gt; capability include a glideslope antenna (possibly included in the existing NAV antenna), equipment to process the frequency pairing, and a glideslope display. I know that all LOC frequencies fall within the range of VOR frequencies (108.10–111.95 MHz and 108.0–117.95 MHz respectively) and the frequency spacing is compatible. I also understand that the circuitry required for VOR signal processing includes circuitry &lt;em&gt;not&lt;/em&gt; required for LOC signal processing (that circuitry which can deteriorate over time requiring the periodic VOR accuracy checks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given all this, my questions are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Is LOC signal processing an inherent capability of a NAV receiver:&lt;/strong&gt; Will any given VHF NAV radio receiver be inherently capable of processing a LOC signal, or is there additional circuitry required for that capability beyond that required for VOR signal processing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And if not,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Are there NAV receivers incapable of LOC signal processing:&lt;/strong&gt; If LOC signal processing is &lt;em&gt;not&lt;/em&gt; an inherent capability of a VHF NAV receiver, are there NAV receivers that were built without the LOC signal processing capability? In other words, is it possible that a pilot or mechanic would encounter a NAV receiver that did not have LOC signal processing capability? More precisely—from a pilot's standpoint—might I encounter a NAV radio that I could use to navigate tuned to a VOR station but not a LOC station?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-02-16T18:28:33.377" Title="Is a VHF NAV receiver inherently capable of processing a LOC signal?" Tags="&lt;avionics&gt;&lt;ifr-navigation&gt;&lt;localizer&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25295" PostTypeId="1" AcceptedAnswerId="25303" CreationDate="2016-02-16T16:16:17.730" Score="0" ViewCount="364" Body="&lt;p&gt;I've seen on many airports a lot of vehicles transporting some &quot;brown boxes&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g8zW0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g8zW0.jpg&quot; alt=&quot;ags&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea of what is this?&#xA; (I don't ask what's exactly inside this box, just in general) &#xA;Source: &lt;a href=&quot;http://www.123rf.com/photo_5673542_air-transportation-airplane-loading-cargo.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;123rf.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CQuSi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CQuSi.jpg&quot; alt=&quot;klma330&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zB32b.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zB32b.jpg&quot; alt=&quot;a330&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What that may be?  Baggage? : in case that boxes contain baggage, why don't they put it as loose baggage or in ULD's. May that be other type of cargo?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-16T21:25:32.507" LastActivityDate="2016-02-17T12:56:30.877" Title="What does this vehicle transport?" Tags="&lt;ground-operations&gt;" AnswerCount="3" CommentCount="11" ClosedDate="2016-02-17T13:16:53.360" ContentLicense="CC BY-SA 3.0" />
  <row Id="25296" PostTypeId="2" ParentId="25196" CreationDate="2016-02-16T16:38:47.677" Score="6" Body="&lt;p&gt;The check is performed to make sure the prop will actually feather when pulled past the feather gates.  You'll be in a world of hurt if you are not able to feather a prop if the engine quits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple hundeed RPM drop is acceptable (generally).  So called &quot;deep cycling&quot; props does nothing for you.  I suppose that there are some goofy mechanisms on oddball planes that require a deep cycle but the vast majority only require you to observe a small drop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, you are checking that the governor can control the prop, not how far the prop can travel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 1: I should add that you should just do whatever the POH/AFM tells you to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit 2: a pilot is typically looking for an oil pressure change, manifold pressure rise, and an RPM drop with each prop cycle.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2018-01-03T16:47:48.930" LastActivityDate="2018-01-03T16:47:48.930" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25297" PostTypeId="2" ParentId="25295" CreationDate="2016-02-16T16:49:55.520" Score="-3" Body="&lt;p&gt;&lt;a href=&quot;https://www.ups.com/media/news/en/shipping_batteries.pdf&quot; rel=&quot;nofollow&quot;&gt;shipping batteries&lt;/a&gt; could be a possibility.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-02-16T16:49:55.520" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25298" PostTypeId="1" CreationDate="2016-02-16T17:05:42.933" Score="8" ViewCount="997" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_H-5&quot;&gt;Sikorsky_H-5&lt;/a&gt; was made in 1943 but used an &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_R-985_Wasp_Junior&quot;&gt;engine&lt;/a&gt; released in the 1930's. It seems to me that the used that applied to helicopters, specifically in warfare, could have applied much earlier. Things like SAR, Medivac, spotting and ground support would all have been useful in the Second World War. &lt;/p&gt;&#xA;" OwnerUserId="6854" LastEditorUserId="6854" LastEditDate="2016-02-16T17:19:08.593" LastActivityDate="2016-02-16T23:14:02.093" Title="Why did it take so long for helicopters to be developed/in use?" Tags="&lt;helicopter&gt;&lt;aviation-history&gt;&lt;aircraft-development&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25300" PostTypeId="2" ParentId="25292" CreationDate="2016-02-16T17:21:43.063" Score="5" Body="&lt;p&gt;Any VHF radio can receive the &lt;strong&gt;carrier&lt;/strong&gt; signal of a LOC signal but to use it, you need dedicated circuitry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The LOC transmitter transmits the carrier wave, frequency modulated with two side lobes of 90Hz and 150Hz.  In order to use the LOC signal, circuitry needs to exist which will filter out the 90 and 150Hz then measure the difference between them to determine where in the beam the receiver is located.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This circuitry is dedicated to the ILS receiver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's a similar story for GS which simply uses lobes above each other, rather than left and right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is LOC signal processing an inherent capability of a NAV receiver&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there NAV receivers incapable of LOC signal processing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.  All of them which do not have an ILS function (e.g. &lt;a href=&quot;https://www.rockwellcollins.com/Data/Products/Navigation_and_Guidance/Radio_Navigation_and_Landing/VOR-900_VHF_Omnidirection_Range-Marker_Beacon_Receiver.aspx&quot; rel=&quot;nofollow&quot;&gt;the Rockwell Collins VOR-900&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[ BEGIN Mythbusters Territory]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've just tuned my hand held airband receiver to the ILS of my local airport.  I think I can make out the beat frequencies from the 90 and 150Hz although I doubt that the low pass filter is letting much 90Hz through.  I guess it's optimised for voice reception so probably cuts off at about 100 or 120Hz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next time I drive past the end of the runway, I'm going to test whether I can detect any change in the beat frequencies as I drive through the lobes.  There is a convenient hill about a mile from the threshold which will put me a couple of hundred feet above so I should be in the beam.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess it might just be plausible to hear when you are going left and right of the centre line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll report back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[END Mythbusters Territory]&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="64" LastEditDate="2016-02-16T18:28:33.377" LastActivityDate="2016-02-16T18:28:33.377" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="25301" PostTypeId="2" ParentId="25265" CreationDate="2016-02-16T17:22:06.240" Score="1" Body="&lt;p&gt;I am not aware of mechanics watching civil aircraft start up. They usually have far better things to do. Aircrew are responsible for the aircraft at this point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question on a twin is about directional control not safety. How easy is it to taxi on one engine without losing control or stressing the aircraft or tyres in any way? I think this probably depends on the aircraft, some will be easier than others. Also if its a piston twin, you don't want to wait for the other engine to warm up when you are ready for departure. Some four engined aircraft might taxi on two engines - one either side but I've never heard of twins doing this routinely.&lt;/p&gt;&#xA;" OwnerUserId="9679" LastActivityDate="2016-02-16T17:22:06.240" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25302" PostTypeId="2" ParentId="25298" CreationDate="2016-02-16T17:44:58.503" Score="12" Body="&lt;p&gt;The useful payload and the robustness of rotorcraft were not sufficient for the rough conditions on the front. Only when turbines were available with their much better power-to-weight ratio and high reliability did helicopters offer a real advantage to the military.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Juan_de_la_Cierva&quot; rel=&quot;nofollow&quot;&gt;de Cierva&lt;/a&gt; autogyro line was begun in 1920, but de Cierva focused on building unstallable GA aircraft, not weapons. The same can be said for &lt;a href=&quot;https://en.wikipedia.org/wiki/Henrich_Focke&quot; rel=&quot;nofollow&quot;&gt;Henrich Focke&lt;/a&gt;, who improved on de Cierva's designs (which he built under license) with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_61&quot; rel=&quot;nofollow&quot;&gt;Fa-61&lt;/a&gt;, which is considered the first practical helicopter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only helicopters to be used by the military were the designs of &lt;a href=&quot;https://en.wikipedia.org/wiki/Anton_Flettner&quot; rel=&quot;nofollow&quot;&gt;Anton Flettner&lt;/a&gt; who used two intermeshing rotors with considerable success, the transport helicopter &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Achgelis_Fa_223&quot; rel=&quot;nofollow&quot;&gt;Fa-223&lt;/a&gt; with two rotors on outriggers and the Sikorsky &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_R-4&quot; rel=&quot;nofollow&quot;&gt;R-4&lt;/a&gt;. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Flettner_Fl_282&quot; rel=&quot;nofollow&quot;&gt;Flettner 282&lt;/a&gt; and the Fa-223 were ordered by the Luftwaffe, but development took a long time, with many new problems to be overcome. In the end, they came too late to be used in any quantity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Sikorsky design was unstable and needed considerable pilot attention. Just &lt;a href=&quot;https://www.youtube.com/watch?v=PnbKZOG2gII&quot; rel=&quot;nofollow&quot;&gt;watch how poor Igor is working the stick&lt;/a&gt; to keep the VS-300 straight! It also needed years of refinement before it could be used by the military. This was the R-4 which saw limited use for rescue missions from 1944 on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just because something can be demonstrated once does not imply it is ready for widespread use.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-16T23:14:02.093" LastActivityDate="2016-02-16T23:14:02.093" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25303" PostTypeId="2" ParentId="25295" CreationDate="2016-02-16T18:04:33.840" Score="6" Body="&lt;p&gt;Your question is rather broad and somewhat unclear, but what you have is a picture of a baggage tug and cart. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The carts are loaded with passenger baggage or cargo, then strings of them are pulled to the aircraft by the tug before being loaded on to the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on the additional pictures, I think what you're after would be called &lt;code&gt;palletized cargo&lt;/code&gt;. It's stuff, put in boxes, placed on pallets, wrapped with &lt;a href=&quot;https://en.wikipedia.org/wiki/Stretch_wrap&quot; rel=&quot;nofollow&quot;&gt;stretch wrap&lt;/a&gt;, with a net thrown over the top and hooked down to keep it from sliding off the pallet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is most likely &lt;em&gt;not&lt;/em&gt; passenger baggage. That's either loaded one piece at a time by hand, or in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;nofollow&quot;&gt;ULD&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're asking what's in &lt;em&gt;those&lt;/em&gt; particular boxes, you'd have to zoom in quite close to find a label on a box to even have a chance of figuring it out. Just about anything can be and is shipped in a brown cardboard box, from anywhere to anywhere in the world. &lt;em&gt;This&lt;/em&gt; question is &lt;em&gt;far&lt;/em&gt; too broad and off topic for Aviation.SE, and probably &lt;em&gt;any&lt;/em&gt; SE. &lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2016-02-17T12:56:30.877" LastActivityDate="2016-02-17T12:56:30.877" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25304" PostTypeId="1" AcceptedAnswerId="25306" CreationDate="2016-02-16T18:25:48.257" Score="3" ViewCount="1370" Body="&lt;p&gt;I'm just from FSX background and not familiar with real procedures. In real world situations, when the pilot is vectored to the runway, does the ATC provide the pilot with the runway frequency and course setting or does the pilot have to know these already from somewhere (logs, FMS, etc)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean in a real world case does ATC say for example &quot;Expect ILS runway 24 left&quot; or do they tell the pilot the nav frequency and course setting too? Or does the pilot obtain the setting for approach like the FSX GPS? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If possible please provide me with a sample communication for landing between ATC and Pilot. (Really curious) &lt;/p&gt;&#xA;" OwnerUserId="8077" LastEditorUserId="19" LastEditDate="2016-07-28T13:11:37.433" LastActivityDate="2016-07-28T13:11:37.433" Title="Does ATC provide ILS frequency and course setting for the runway in use?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;instrument-flight-rules&gt;&lt;approach&gt;&lt;ils&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25305" PostTypeId="1" CreationDate="2016-02-16T18:39:28.870" Score="5" ViewCount="1393" Body="&lt;p&gt;I'm still doing my PPL, but one question has puzzled me recently. During an internal exam before my first solo nav on a C150, the examiner pulled the throttle, so I would do a simulated emergency landing. I chose a field right to me, and with a good gliding speed and without any flaps did a 180 turn (base+final) and found myself flying straight into power lines before the field. We had to go around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The examiner showed me how it should be done. After the base turn, he deployed flaps 10 and then on final 20. We flew way above the power lines. Now I'm not sure all the altitudes and turning points were the same, but he meant this to show me that I should have used flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding had always been that the use of flaps during emergency landing should be restricted to the final leg from the point that you are certain you will make the airfield. My instructor (not the examiner) had the same view and could not explain it to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any idea?&lt;/p&gt;&#xA;" OwnerUserId="13553" LastEditorUserId="19" LastEditDate="2016-11-01T08:32:31.440" LastActivityDate="2016-11-01T08:32:31.440" Title="How should flaps be used during an emergency landing (PPL)?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;ppl&gt;&lt;flaps&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25306" PostTypeId="2" ParentId="25304" CreationDate="2016-02-16T18:45:35.530" Score="10" Body="&lt;p&gt;When nearing their destination, pilots will be checking weather and &lt;a href=&quot;https://aviation.stackexchange.com/q/7662/1696&quot;&gt;airport information&lt;/a&gt;. This will let them know which runways are being used for landings and what type of approaches are being used. ATC will also tell each aircraft what runway and approach they can expect in advance, as in your example, &quot;Expect ILS approach runway 24 left&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the pilots know the runway and approach, they can reference the corresponding chart (like the ones in &lt;a href=&quot;https://aviation.stackexchange.com/q/1873/1696&quot;&gt;this question&lt;/a&gt;). Pilots are required to have these charts available, traditionally paper copies but more recently being replaced by &lt;a href=&quot;https://aviation.stackexchange.com/q/254/1696&quot;&gt;electronic copies&lt;/a&gt;. This will give them all of the information about the procedure, including the localizer frequency. Besides programming the frequency, the crew will also review the other important requirements of the approach and landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC does have access to this information as well, and can provide it if they feel they need to confirm the pilot has the right frequency, or if the pilot asks.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-16T18:53:46.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25307" PostTypeId="2" ParentId="25305" CreationDate="2016-02-16T19:20:43.323" Score="6" Body="&lt;p&gt;Specifically in your case you may have lost more altitude in the turn than your instructor or your turns were less coordinated etc. A wide variety of other variables that are hard to note with out accurate course data could have led to your outcome. You would have had to enter the maneuver at the same place/altitude to get similar results and the wind would have an effect here as well. Did you have a head wind or tail wind? Its worth covering some general procedures for this maneuver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When turning under glide its important to watch your airspeed and know how the plane will sink in a turn since you sacrifice some lift for the turn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember flaps allow you to make a steeper approach with out gaining airspeed but what that also means is your ground speed is effected (slowed). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it comes to the emergency landing procedure you are free to use flaps at your discretion and as mentioned its generally taught to use them once you are sure you have the field made. If the field is long enough you should shoot for a mid point incase you come up a bit short. Likewise if you are high you can go full flaps and slip it to lose altitude fast (if your instructor has not shown you how to slip a plane to lose altitude I would advise asking him to do so).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-02-16T19:20:43.323" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25308" PostTypeId="1" CreationDate="2016-02-16T19:30:33.237" Score="11" ViewCount="1386" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Sikorsky_SH-60_Seahawk#MH-60R&quot; rel=&quot;nofollow&quot;&gt;MH-60R helicopter&lt;/a&gt; has a horizontal Stabilator that consists of three subassemblies, RH Stabilator, LH Stabilator, and Center Stabilator.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the aircraft fly without the RH Stabilator?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the aircraft fly without the entire Stabilator?&lt;/p&gt;&#xA;" OwnerUserId="13554" LastEditorUserId="7532" LastEditDate="2017-12-25T16:27:19.220" LastActivityDate="2017-12-25T16:27:19.220" Title="Can the MH-60 helicopter fly without one or all of the stabilators?" Tags="&lt;helicopter&gt;&lt;control-surfaces&gt;&lt;airworthiness&gt;&lt;uh-60&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25309" PostTypeId="1" AcceptedAnswerId="25333" CreationDate="2016-02-16T20:35:01.927" Score="1" ViewCount="1105" Body="&lt;p&gt;A typical ATIS broadcast includes the QNH (&quot;altimeter&quot; for the cousins).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My habit is to read this back since I have effectively been given the setting by ATC and it is required for my startup. For example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Finden 37 with information Delta, the QNH 1022.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can't find any reference on whether this is required or not.  Additionally, do any CPLs or ATCOs on here consider this to be good or bad practice?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone wants me to tag with a jurisdiction, then it would be UK CAA since that is where I fly but I am interested in all responses.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1696" LastEditDate="2016-02-16T21:26:07.170" LastActivityDate="2016-02-17T06:48:48.727" Title="Should you read back the QNH from an ATIS broadcast?" Tags="&lt;air-traffic-control&gt;&lt;caa-uk-regulations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25310" PostTypeId="1" AcceptedAnswerId="25318" CreationDate="2016-02-16T20:44:06.197" Score="17" ViewCount="12101" Body="&lt;p&gt;Why do all new European fighter jets - &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurofighter_Typhoon&quot; rel=&quot;noreferrer&quot;&gt;Typhoon&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_JAS_39_Gripen&quot; rel=&quot;noreferrer&quot;&gt;Gripen&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Rafale&quot; rel=&quot;noreferrer&quot;&gt;Rafale&lt;/a&gt; have delta wings? As I know, they were all designed separately. And they are not new either. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any particular advantage that caused the Europeans to choose to do it like it is? Is it because of traditions? Or do they use the same software? (cheeky grin)&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="15311" LastEditDate="2020-04-17T17:16:24.140" LastActivityDate="2020-04-17T17:16:24.140" Title="Why do all new European fighter jets have delta wings?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;fighter&gt;&lt;jet&gt;&lt;delta-wing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25311" PostTypeId="1" AcceptedAnswerId="25375" CreationDate="2016-02-16T20:50:37.733" Score="0" ViewCount="1821" Body="&lt;p&gt;What are the main differences of this two types of flights?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-17T18:59:59.047" LastActivityDate="2016-02-18T17:46:43.597" Title="What is the difference between a Sub-Charter Flight and a Codeshare Flight?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25312" PostTypeId="1" AcceptedAnswerId="25327" CreationDate="2016-02-16T20:51:01.023" Score="43" ViewCount="17062" Body="&lt;p&gt;I came across &lt;a href=&quot;https://aviation.stackexchange.com/questions/14952/why-do-fighter-aircraft-manufacturers-still-focus-on-making-their-planes-more-do&quot;&gt;this question&lt;/a&gt; on dogfight-capable fighter jets still being made. If all aircraft become so stealthy, how will they fight each other? Only in dogfights, I presume. Or am I wrong?&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="3386" LastEditDate="2018-01-18T23:26:41.220" LastActivityDate="2018-01-18T23:26:41.220" Title="If all fighter jets become stealthy, how will they fight each other in the future? In dogfights?" Tags="&lt;military&gt;&lt;fighter&gt;&lt;stealth&gt;&lt;dogfighting&gt;" AnswerCount="6" CommentCount="14" FavoriteCount="20" ContentLicense="CC BY-SA 3.0" />
  <row Id="25315" PostTypeId="2" ParentId="25309" CreationDate="2016-02-16T21:21:49.980" Score="0" Body="&lt;p&gt;ICAO Doc 4444 Section 4.5.7.5.1 states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The flight crew shall read back to the air traffic&#xA;  controller safety-related parts of ATC clearances and instructions&#xA;  which are transmitted by voice. The following items shall&#xA;  always be read back:&#xA;  ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c) runway-in-use, altimeter settings, SSR codes, level&#xA;  instructions, heading and speed instructions and,&#xA;  &lt;em&gt;whether issued by the controller or contained in automatic&#xA;  terminal information service (ATIS) broadcasts&lt;/em&gt;,&#xA;  transition levels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7214" LastEditorUserId="7443" LastEditDate="2016-02-17T00:33:31.343" LastActivityDate="2016-02-17T00:33:31.343" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25316" PostTypeId="1" AcceptedAnswerId="25320" CreationDate="2016-02-16T21:29:51.023" Score="10" ViewCount="1984" Body="&lt;p&gt;Suppose I lost my radio communication while en-route, I am following the cleared route to the last fix. I am flying the higher of my last assigned altitude and MEA. Then, I am holding at my last en-route fix and the filed expected arrival time is coming. In this case, how may I start to descent and commerce an approach? regarding which IAP to use and which IAF to head for, provided that the last en-route fix is none of IAFs in any IAPs and my last altitude is much higher than the minimums prescribed in the IAPs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;POST EDIT: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Transponder is on 7600&lt;/li&gt;&#xA;&lt;li&gt;No VMC within the range of fuel&lt;/li&gt;&#xA;&lt;li&gt;Destination airport is tower-controlled&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-04-03T22:56:16.367" LastActivityDate="2016-04-03T23:44:32.020" Title="How to start an approach in IMC loss of communication under IFR?" Tags="&lt;instrument-flight-rules&gt;&lt;radio-communications&gt;&lt;instrument-procedures&gt;&lt;lost-communications&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25317" PostTypeId="2" ParentId="25047" CreationDate="2016-02-16T21:30:04.080" Score="1" Body="&lt;p&gt;&lt;a href=&quot;http://www.aisro.ro/&quot; rel=&quot;nofollow&quot;&gt;here &lt;/a&gt; is an example of the charges one has to pay to fly in Romanian airspace. Navigate to publications , AIP , AIP, open chapter GEN , section &quot;Charges for Aerodromes/Heliports and Air Navigation Services&quot; .&lt;/p&gt;&#xA;" OwnerUserId="7214" LastEditorUserId="7214" LastEditDate="2016-02-17T07:01:09.903" LastActivityDate="2016-02-17T07:01:09.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25318" PostTypeId="2" ParentId="25310" CreationDate="2016-02-16T22:12:36.917" Score="25" Body="&lt;p&gt;No, they were not designed separately. They were designed by people who had all participated in collaborations before. The origin was the research into unstable configurations performed by &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt-B%C3%B6lkow-Blohm&quot; rel=&quot;noreferrer&quot;&gt;MBB&lt;/a&gt; in Germany in the late 1970s by a modified F-104, the control configured vehicle &lt;a href=&quot;http://theaviationist.com/2014/03/07/f-104-cvv-typhoon/&quot; rel=&quot;noreferrer&quot;&gt;F-104 CCV&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eSMY2.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eSMY2.png&quot; alt=&quot;F-104 CCV&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;F-104 CCV (picture &lt;a href=&quot;http://media.moddb.com/images/articles/1/108/107696/auto/f-104g-ccv_r1p.png&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, MBB designed the Taktisches Kampfflugzeug 90 (or TKF-90), the first design of an unstable delta canard which promised unmatched maneuverability. Since Germany could not afford to develop the aircraft all by itself, collaborations were started with both Dassault and BAe, so that French and British engineers could learn of the advantages of this layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BYY0s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BYY0s.jpg&quot; alt=&quot;MBB TKF-90 concept&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MBB TKF-90 concept (picture &lt;a href=&quot;http://aviadejavu.ru/Images6/AK/AK2010-03/36-3.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, BAe collaborated with MBB and joined the TKF-90 design, resulting in the European Collaborative Fighter proposal, only to continue on their own with two delta canard designs of their own, P.106 and P.110. P.106 had one engine and one vertical tail while P.110 had two of both, like the TKF-90. P.106 was rejected by the RAF, but went into a collaboration with Saab and eventually became the JAS-39.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be fair, the first company to build and fly a closely-coupled delta canard was Saab with their &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_37_Viggen&quot; rel=&quot;noreferrer&quot;&gt;Saab 37 Viggen&lt;/a&gt;. Saab has a long history of innovative work, beginning with ejection seats in 1942 and sweptback jets in 1948. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U2olw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U2olw.jpg&quot; alt=&quot;Saab 37 Viggen&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Saab 37 Viggen (picture &lt;a href=&quot;http://2.bp.blogspot.com/-o3cAfdaDt8I/T_Ajbb2H7TI/AAAAAAAAABE/3hlu6C6Guc0/s1600/Saab+37+Viggen+003.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). In contrast to the TKF-90 it was an aerodynamically stable layout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, MBB collaborated with Dassault in the Future European Fighter Aircraft (FEFA) program, so the French side learned of the advantages of a delta canard. Eventually, the French wanted less air-to-air capabilities and a smaller aircraft for better export chances, and the remaining FEFA partners continued in the European Fighter Aircraft (EFA) program which resulted in the EF-2000, while Dassault went it alone with the Rafale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EF-2000 is hampered to this day by this heritage. Its wing area was decreed by &lt;a href=&quot;https://en.wikipedia.org/wiki/Margaret_Thatcher&quot; rel=&quot;noreferrer&quot;&gt;Maggie Thatcher&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Helmut_Kohl&quot; rel=&quot;noreferrer&quot;&gt;Helmut Kohl&lt;/a&gt; to be no more than 50 m² when a 60 m² wing would had resulted in a much more capable design. Next, the British engineers insisted on a straight leading edge, ignorant of the fact that only a cranked delta would provide good post-stall pitch characteristics. They also refused to accept a &lt;a href=&quot;https://en.wikipedia.org/wiki/Stealth_aircraft&quot; rel=&quot;noreferrer&quot;&gt;faceted design&lt;/a&gt;, and the German side could only rescue the &quot;smiling intake&quot; in order to reduce the radar cross section of the EF-2000 somewhat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/no6AT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/no6AT.jpg&quot; alt=&quot;&amp;quot;Smiling intake&amp;quot; of the EF-2000&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Smiling intake&quot; of the EF-2000 (picture &lt;a href=&quot;http://www.b-domke.de/AviationImages/Typhoon/Images/EF2000(T)_CSX55092_10565.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The curved contour avoids corner reflections of electromagnetic waves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And don't get me started on the odd location of the airbrake: On the center fuselage where it is least effective at high angle of attack and will blanket the single vertical tail. Designed by a committee with too many British engineers.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-18T21:33:17.087" LastActivityDate="2016-02-18T21:33:17.087" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25319" PostTypeId="2" ParentId="25312" CreationDate="2016-02-16T23:09:23.330" Score="30" Body="&lt;p&gt;Using infrared sensors, a fast-moving airplane can be spotted at several 100 km distance if it flies high enough. The friction heating of the fuselage nose and leading edges will stick out against a cold background.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, by networking radars and combining the radar data in a sophisticated computer program, stealth aircraft can be tracked reliably even in darkness or clouds. A &lt;a href=&quot;https://aviation.stackexchange.com/questions/1798/do-similar-angles-on-a-plane-make-it-more-stealthy/12652?s=1%7C0.2676#12652&quot;&gt;faceted design&lt;/a&gt; will send out a strong return signal over narrowly defined angles, and if you have enough radar receivers, those blips will come fast enough to stitch together the path of the stealth aircraft causing them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good part of stealth is propaganda.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-16T23:09:23.330" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="25320" PostTypeId="2" ParentId="25316" CreationDate="2016-02-16T23:38:49.550" Score="10" Body="&lt;p&gt;The FAA says (per 14 CFR 91.185):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the clearance limit is not a fix from which an approach begins,&#xA;  leave the clearance limit at the expect-further-clearance time if one&#xA;  has been received, or if none has been received, upon arrival over the&#xA;  clearance limit, and proceed to a fix from which an approach begins&#xA;  and commence descent or descent and approach as close as possible to&#xA;  the estimated time of arrival as calculated from the filed or amended&#xA;  (with ATC) estimated time en route.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This seems to answer your question unless you have a more specific one. You can descend to an IAF as you see fit and commence any approach. ATC will clear the way.&lt;/p&gt;&#xA;" OwnerUserId="7443" LastActivityDate="2016-02-16T23:38:49.550" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25321" PostTypeId="2" ParentId="25312" CreationDate="2016-02-17T00:05:15.370" Score="11" Body="&lt;p&gt;FIrst, stealth does not make an aircraft invisible- it just makes them harder to detect. Stealth (or correctly, Very Low Observable (VLO)) aircraft can and are detected by radars and other surveillance mechanisms.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Stealth aircraft are usually optimised for low observability in some radar frequency (mostly in Ku- and X- bands). This means that they can be detected by radars in other frequencies at longer distances. Even if the exact location is not known, knowledge of the general location can enable tracking with more powerful radar.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The main thrust of fifth gen aircraft (along with stealth) is sensor fusion and networking of aircraft; basically, if the aircraft can 'talk' to each other and compare their radar returns with that of other aircraft and ground radars, a much better picture of the battlespace emerges, which makes identificaiton of stealth aicraft easier. After all, the VLO aircraft are not equally stealthy from all angles.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Infrared Search and Track (IRST) systems can detect VLO aircraft from much larger distances compared to radars and the US is just now warming up to the idea- Both Russian and European aircraft have been using IRST for quite some time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another point is that stealth comes at a cost- for targeting enemy aircraft, you have to switch on you radar. The inverse square law of radar strength means that you'll be detected much before the radar returns from the opponent will be detectable by you. One way to think about the fight between two VLO aircraft is that it's like fight between two gunslingers with flashlights in a dark room. Here, the first one to switch on the flashlight (radar) is at a distinct disadvantage. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One tradeoff in VLO design is that that weapons are carried internally. During weapons release, the radar signature of the aircraft spikes, which can aid in detection.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Finally, the VLO characteristics are important only in BVR area. Once the dogfight turns into WVR, stealth aircraft has no distinct advantage over any other aircraft (see the F-35 Vs F-16 case).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="167" LastEditDate="2016-02-17T00:37:46.317" LastActivityDate="2016-02-17T00:37:46.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25322" PostTypeId="1" CreationDate="2016-02-17T00:24:42.613" Score="-1" ViewCount="392" Body="&lt;p&gt;Can a WSC aircraft registered SLSA be used commercially i.e., local tours for hire?&#xA;FAA regulations do not seem to address a commercial rating for WSC.&lt;/p&gt;&#xA;" OwnerUserId="13556" LastEditorUserId="167" LastEditDate="2016-02-17T00:35:32.060" LastActivityDate="2016-03-18T12:56:59.593" Title="Can weight shift control aircraft be used commercially?" Tags="&lt;faa-regulations&gt;&lt;faa&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25323" PostTypeId="1" CreationDate="2016-02-17T00:42:36.783" Score="10" ViewCount="4917" Body="&lt;p&gt;I want to ask about the jet fuel purchasing cycle. Is it the airport that buys the jet fuel from refineries and then sells it to the airlines? Or do airlines buy fuel directly from refineries?&lt;/p&gt;&#xA;" OwnerUserId="13557" LastEditorUserId="15637" LastEditDate="2016-12-08T16:51:32.920" LastActivityDate="2017-04-03T12:30:25.427" Title="Who sells aviation fuel to airports?" Tags="&lt;airport&gt;&lt;fuel&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25324" PostTypeId="1" AcceptedAnswerId="25328" CreationDate="2016-02-17T01:24:01.903" Score="5" ViewCount="1273" Body="&lt;p&gt;For example on an MD-88, is the center of gravity on the back of the plane because the empennage, wings and engines are located there? So they would have to put most of the cargo on the back of the plane?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="595" LastEditDate="2016-02-18T16:10:15.357" LastActivityDate="2016-02-18T16:10:15.357" Title="How to balance the cargo on a plane with the wings further aft?" Tags="&lt;stability&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25325" PostTypeId="2" ParentId="23753" CreationDate="2016-02-17T02:33:35.053" Score="6" Body="&lt;p&gt;It took me a little bit to figure out the underlying reason for asking this question and it has to do with logging flight time.  For example, in a single pilot operation with an autopilot, the second pilot is not required and therefore cannot log the flight time at all even though their company may want them there.  The FARs don't allow the second pilot to log the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulation that governs logging of flight time is 61.51.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;61.51(h) Logging training time. (1) A person may log training time when that person receives training from an authorized instructor in an aircraft, flight simulator, or flight training device.&#xA;  (2) The training time must be logged in a logbook and must:&#xA;  (i) Be endorsed in a legible manner by the &lt;strong&gt;authorized instructor&lt;/strong&gt;; and&#xA;  (ii) Include a &lt;strong&gt;description of the training given&lt;/strong&gt;, the length of the training lesson, and the authorized instructor's signature, certificate number, and certificate expiration date.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the question becomes what training was given during the revenue Part 135 flight and were you an authorized instructor? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The term &lt;strong&gt;Authorized Instructor&lt;/strong&gt; is only found in Part 61.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;61.1. Authorized instructor means—&#xA;  (i) A person who holds a ground instructor certificate issued under part 61 of this chapter and is in compliance with §61.217, when conducting ground training in accordance with the privileges and limitations of his or her ground instructor certificate;&#xA;  (ii) A person who holds a flight instructor certificate issued under part 61 of this chapter and is in compliance with §61.197, when conducting ground training or flight training in accordance with the privileges and limitations of his or her flight instructor certificate; or&#xA;  (iii) A person authorized by the Administrator to provide ground training or flight training under part 61, 121, 135, or 142 of this chapter when conducting ground training or flight training in accordance with that authority.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since it is a Part 135 revenue flight I would believe the CFI would have to comply with section 135.338 and 135.340.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;135.340(a) No certificate holder may use a person nor may any person serve as a flight instructor unless—&#xA;  (1) That person has satisfactorily completed initial or transition flight instructor training; and&#xA;  (2) Within the preceding 24 calendar months, that person satisfactorily conducts instruction under the observation of an FAA inspector, an operator check airman, or an aircrew designated examiner employed by the operator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the authorized instructor has complied with 135.338 and 135.340 they are also bound to the training program for the 135 company.  If that training stipulates you can give dual given during revenue flights than you are more than welcome to do so.  If there is no provision in the training program to provide instruction during revenue flight then it should not be done.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The best option is to request a legal interpretation on the validity of what you are wanting to do.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-17T02:33:35.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25326" PostTypeId="2" ParentId="25322" CreationDate="2016-02-17T02:35:43.570" Score="0" Body="&lt;p&gt;All commercial operations require a pilot who holds a commercial or ATP certificate with appropriate ratings at a commercial level or higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no provision in the FARs to give pilots a commercial WSC rating.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-17T02:35:43.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25327" PostTypeId="2" ParentId="25312" CreationDate="2016-02-17T04:05:59.503" Score="106" Body="&lt;h1&gt;Table of contents&lt;/h1&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Future focii&lt;/strong&gt; &lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Short answer&lt;/strong&gt; - Important: stealth, sensors (radar &amp;amp; IR), data fusion, networking, long-range weapons. Unimportant: dogfighting with guns.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Future counter-detection and counter-measures&lt;/strong&gt; - Important: RF and IR stealth, lasers, hard-kill defenses&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;How will stealth fighters fight each other?&lt;/strong&gt; - including THE MOST IMPORTANT LESSON&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Busting myths&lt;/strong&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: Stealth aircraft can't use radars / radars reveal your location&lt;/strong&gt; - LPI radar&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: IR sensors render stealth obsolete&lt;/strong&gt; - IR range is short; shorter than radar range against nonstealthy a/c, but greater than radar range against stealthy a/c&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: US lags behind Russia/Europe in IR tech&lt;/strong&gt; - US had less need (better radars); US has &lt;em&gt;very&lt;/em&gt; good IR tech&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: Stealth makes you invisible to radar&lt;/strong&gt;  - &lt;em&gt;very&lt;/em&gt; hard to see, not invisible&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: Stealth is obsolete / a hoax / just marketing&lt;/strong&gt; - &lt;em&gt;vastly&lt;/em&gt; reduced detection range; more efficient jamming; dictate engagements&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: WWII/low-freq radars make stealth obsolete / an F-117 was shot down with this &lt;em&gt;one simple trick&lt;/em&gt;&lt;/strong&gt; - Low-freq radars have limited use; F-117 story is untrue.&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: most combat is WVR dogfighting&lt;/strong&gt; - not since the 1960s&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Myth: Guns are primary weapons. F-4's were massacred by obsolete MiG-21s in Vietnam because they didn't have guns.&lt;/strong&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;&lt;strong&gt;F-4 guns myth&lt;/strong&gt; - the F-4s did just fine&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Welcome to the BVR missile era&lt;/strong&gt; - where missiles take all the credit, and you usually don't see your enemy&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Resources&lt;/strong&gt; - for modern air combat&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;Glossary&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h1&gt;As aircraft become stealthier, we'll rely more on the following:&lt;/h1&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Non-radio sensing&lt;/strong&gt; &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;IR search and track (IRST)&lt;/li&gt;&#xA;&lt;li&gt;Optical sensing&lt;/li&gt;&#xA;&lt;li&gt;(EO/IR are/can be combined into essentially an EO/IR telescope. Future designs will use multiple bands (MWIR, SWIR, color HDTV), have wider fields of view&lt;/li&gt;&#xA;&lt;li&gt;Mid-future: laser tracking and targeting. &lt;/li&gt;&#xA;&lt;li&gt;High-powered lasers (100s of kW) for fighters &lt;a href=&quot;//youtu.be/Xf2dz_NW1j0&quot; rel=&quot;noreferrer&quot;&gt;won't debut for decades&lt;/a&gt;, but in the meantime they could obtain very high quality bearing, range, speed, and altitude information.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Networking and data fusion&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Highly integrated aircraft sensors&lt;/li&gt;&#xA;&lt;li&gt;Off-board targeting&lt;/li&gt;&#xA;&lt;li&gt;Eg, a very stealthy sensor platform feeding targeting info to less stealthy (even non-stealthy) launch platforms.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Advanced radars&lt;/strong&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Multi-band or broadband radars (integrated mid/high-frequency capabilities)&lt;/li&gt;&#xA;&lt;li&gt;More powerful AESA radars&lt;/li&gt;&#xA;&lt;li&gt;Better processing&lt;/li&gt;&#xA;&lt;li&gt;Multi-static arrays to detect side-aspect radar returns. &lt;/li&gt;&#xA;&lt;li&gt;Side-looking radars. &lt;/li&gt;&#xA;&lt;li&gt;Again, VLO a/c are not equally stealthy in all directions. They are least detectable from the front aspect.&lt;/li&gt;&#xA;&lt;li&gt;For instance, the F-22 was to be upgraded with cheek-mounted, side-looking radars, but these were cancelled to reduce cost.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Even better stealth&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h1&gt;Short answer&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Detection ranges will shrink (against other LO fighters). IR sensors &lt;em&gt;may&lt;/em&gt; become the primary means of detection. Fighters may cruise at &lt;em&gt;low&lt;/em&gt; subsonic speeds to delay detection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radar will still remain the primary sensor for years to come (at least 2 decades, the minimum time for adversaries to field large numbers of LO a/c).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stealth remains essential. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;DATA FUSION and NETWORKING become hugely important&lt;/strong&gt;; large forces must fight as seamless units. Remote targeting will become more common. Very, very stealthy sensors (eg, F-22 successor) may pass targeting info to less stealthy shooters (eg, F-22, F-35, F-15, missile truck with VLRAAMs)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Future AAMs will feature datalinks and multimode seekers (eg, IR, RF, and laser), improving counter-measure resistance. Many AAMs already have datalinks---shooter guides the missile until the missile's own seeker acquires the target. Advanced propulsion systems debut (multi-pulse motors, ducted-rocket/ramrockets, scramjets), yielding longer range, higher speed, imrpoved kinematics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Defenses will improve, requiring deeper magazines (smaller weapons and/or larger internal payload bays).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Space, weight, power, and cooling requirements go up. Aircraft grow larger.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dogfighting will remain rare. Short-range, maneuvering combat will &lt;em&gt;remain&lt;/em&gt; unsurvivable with the advent of reliable, high-performance, high Pk, HOBS missiles and helmet-mounted cueing systems. Also, lasers don't miss. (See &lt;code&gt;Myth: guns&lt;/code&gt; below.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;5th gen fighters (F-22, F-35) will thoroughly dominate over 4th gen fighters (F-15, Su-35, Typhoon). &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Regarding counter-detection and counter-measures&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Fighters will better hide their RF and IR signature. See: engine exhaust troughs on F-117, B-2, YF-23, and 6th gen fighter concepts. See: AETD, ADVENT, and F135 upgrades. Tails may disappear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;EW (eg, jamming) will remain important (See: &lt;code&gt;Myth: Stealth a/c can't use radar&lt;/code&gt;). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;DIRCM (directed IR countermeasures, an IR laser to jam/kill missile IR seekers) will protect fighters and bombers. Already slated for the F-35.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hard-kill missile defenses will debut (likely small anti-missile missiles in near-term; anti-missile lasers 20+ years hence). Today, we rely primarily on soft-kill defenses, like jamming and decoys. &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Answering the question: how will stealth fighters fight each other?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;With better sensors and better stealth. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With mid- to long-range missile shots, but mid-range detection (eg, networked, off-board targeting).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With more lethal weapons (faster/short fight time, improved terminal kinematics, less spoofable sensors).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And with better defenses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, not &lt;em&gt;unimaginably&lt;/em&gt; different from how the F-22 sometimes fights today -- a variation on 5th gen combat. Why? &lt;sup&gt;[See note.]&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Because stealth hasn't changed the most critical component of aerial combat since WWI: SA -- situational awareness -- obtain SA and deny it to your enemy.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;THIS IS BY FAR THE MOST IMPORTANT LESSON IN THIS ENTIRE POST. If you learn nothing else, learn this: SA and OODA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then do exactly this: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Watch &lt;a href=&quot;//youtu.be/zxK6O5--9Z0&quot; rel=&quot;noreferrer&quot;&gt;F-18/22/35 pilot and TOPGUN instructor LtCol Chip Berke&lt;/a&gt; discuss 5th gen combat.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Go to the resources at the bottom of this post. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Read &lt;a href=&quot;//csbaonline.org/publications/2015/04/trends-in-air-to-air-combat-implications-for-future-air-superiority/&quot; rel=&quot;noreferrer&quot;&gt;CSBA's Trends in Air to Air Combat: Implications for Future Air Superiority&lt;/a&gt; (or &lt;a href=&quot;//youtu.be/LmGRn7GirS0&quot; rel=&quot;noreferrer&quot;&gt;listen&lt;/a&gt; to the 1hr presentation) to see how modern air combat is &lt;em&gt;actually&lt;/em&gt; fought.&lt;/li&gt;&#xA;&lt;li&gt;Read &lt;a href=&quot;https://higherlogicdownload.s3.amazonaws.com/AFA/6379b747-7730-4f82-9b45-a1c80d6c8fdb/UploadedImages/Mitchell%20Publications/The%20Radar%20Game.pdf&quot; rel=&quot;noreferrer&quot;&gt;The Radar Game&lt;/a&gt; to find out why SA (and stealth) is so important.&lt;/li&gt;&#xA;&lt;li&gt;Read the &lt;a href=&quot;//redd.it/3cbgs5&quot; rel=&quot;noreferrer&quot;&gt;Gulf War Air Power Survey&lt;/a&gt;. Short, concentrated glimpse into modern air wars.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Learn to fly a fighter.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Seriously. Go pick up &lt;a href=&quot;//aerosoft.com/cgi-local/us/iboshop.cgi?showd,,10285&quot; rel=&quot;noreferrer&quot;&gt;FSX&lt;/a&gt; or &lt;a href=&quot;//digitalcombatsimulator.com/en/&quot; rel=&quot;noreferrer&quot;&gt;DCS&lt;/a&gt; and learn. There's a &lt;a href=&quot;//reddit.com/r/hoggit&quot; rel=&quot;noreferrer&quot;&gt;vibrant community&lt;/a&gt; to help you out if you get stuck. (You only fly the F-16 in FSX, but it has a dynamic campaign. DCS has far more pilotable a/c. Both are VERY realistic.)&lt;/li&gt;&#xA;&lt;li&gt;You'll quickly learn that flying the plane takes a lot more effort and is a lot harder than you imagine. You'll spend much of your time flying the plane (or crashing), not actually fighting... which makes sense because &lt;em&gt;it's the same in real life.&lt;/em&gt; (The F-14 has two crew for a reason.) You'll quickly appreciate the luxuries of modern conveniences (like auto-trim). &quot;Data-fusion&quot; and &quot;networking&quot; will start to mean something. SA will become the difference between life and respawn.&lt;/li&gt;&#xA;&lt;li&gt;You'll also learn that dogfighting is very dangerous. You'll rely more on your AMRAAMs than you guns (once you learn to use the radar ;)). You'll resent the Russian IR AAMs, which don't show up on your radar warning receiver. You'll learn the F-16 is not nearly as agile at medium altitude as headlines led you to believe... especially not when loaded with weapons, fuel, and sensors. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;To give you a snippet of The Radar Game:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In most victories, the target isn't aware they're being shot at. SA was determinant.&lt;/li&gt;&#xA;&lt;li&gt;The most successful aces don't engage in gladiatorial 1v1 dogfights -- more like hit-n-run.&lt;/li&gt;&#xA;&lt;li&gt;Points 1 and 2 apply from WWI to the present day.&lt;/li&gt;&#xA;&lt;li&gt;Reaction times are measured in seconds, a function of detection range and closing speed. Radar increases your reaction time; stealth decreases your enemy's reaction time.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;[Note well: &lt;a href=&quot;//youtu.be/zxK6O5--9Z0?t=270&quot; rel=&quot;noreferrer&quot;&gt;5th gen platforms already operate differently from their predecessors (&quot;speed is life&quot;)&lt;/a&gt;].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Note: it goes w/o saying my prognostications are opinions. Although I'm confident in my predictions -- which are vague but reflect longstanding trends and realistic S&amp;amp;T developments -- I don't pretend certainty.]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Note: timeframe is near- to mid-future.]&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Addressing myths&lt;/h1&gt;&#xA;&#xA;&lt;h2&gt;Myth: Stealth aircraft can't use radars / turning on radars instantly reveals your location&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Low-probability of intercept functionality allow you to use your radar without being detected you. Principals of operation include using wider-frequency bandwidth (wideband), frequency hopping, using a frequency-modulated continuous-wave signal, using only the minimum power required for the task, and pulse compression. &lt;a href=&quot;//en.wikipedia.org/wiki/Low_probability_of_intercept_radar&quot; rel=&quot;noreferrer&quot;&gt;Wiki has a good summary.&lt;/a&gt; AESA radars are particularly suitable because of their thin, pencil-like beams and minimal side-lobes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a &lt;a href=&quot;//web.archive.org/web/20120914110145/http://edocs.nps.edu/npspubs/scholarly/theses/2006/Sep/06Sep_Denk.pdf&quot; rel=&quot;noreferrer&quot;&gt;Naval Postgraduate School thesis&lt;/a&gt; on the detection and jamming of LPI radars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is similar to how LO a/c communicate without being detected. The F-35 is equipped with MADL - &lt;a href=&quot;//en.wikipedia.org/wiki/MADL&quot; rel=&quot;noreferrer&quot;&gt;multifunction advanced datalink&lt;/a&gt; - a stealthy, secure, minimum power, high data rate, line of sight comms system. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: IR sensors render stealth obsolete&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Bodies heat up when moving through air. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vid: &lt;a href=&quot;//youtu.be/v5VuCsQJy8Y&quot; rel=&quot;noreferrer&quot;&gt;F-16 seen through an F-35's EODAS&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vid: &lt;a href=&quot;//youtu.be/aMvYVunblXc?t=953&quot; rel=&quot;noreferrer&quot;&gt;F-15E in IR&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;IR sensors do &lt;em&gt;not&lt;/em&gt; see as far as radar&lt;/strong&gt; (contrary to other answers here).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Against 4th gen fighters (non-stealthy platforms):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;IRST detection range is typically measured in low-dozens of miles.&lt;/li&gt;&#xA;&lt;li&gt;The F-15's radar ranges out to 100 nmi&lt;/li&gt;&#xA;&lt;li&gt;The F-22's radar ranges out to 150 nmi&lt;/li&gt;&#xA;&lt;li&gt;The E-3 Sentry's radar ranges out to 400 nmi&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For reference, the F-14's optical (not IR) system could ID and track bombers out to 50 nmi. Perhaps 15-25 nmi for fighters. (Some IR bands are less readily  absorbed by the air than visible light.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The PIRATE IRST may detect a VLO fighter (with RF and some IR reduction) from these ranges (CSBA):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Altitude  | Mach | Stag temp | Ambient | Contrast | Detection range&#xA;==========|======|===========|=========|==========|================&#xA;45,000 ft | 1.8  |  85 C     | -56 C   | 141 K    | 150 nmi&#xA;45,000 ft | 0.8  | -28 C     | -56 C   |  28 K    |  48 nmi&#xA;45,000 ft | 0.5  | -45 C     | -56 C   |  17 K    |&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(150 nmi figure assumes no afterburner, ie supercruise.)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While IR is harder than radar to jam at long range, it can't estimate target range as easily.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: US lags behind Russia/Europe in IR tech&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Again, IR sensors don't see as far as radar, but they are harder to jam from long range. Historically, NATO fielded better radars and jammers than the Soviets, who therefore couldn't rely as heavily on their radars. So the Russians added IRST capabilities to augment their radars.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember also that the US flies dozens of AWACS that usually detect enemy a/c long before even an F-15's radar. So IRST wasn't as critical for US fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22 has a space reservation for IR sensors, but that upgrade was cut to reduce costs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-14 received an EOST relatively early because its main targets were large, Soviet bombers, which are easier to detect. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The US eventually added IRST to late-block F-16's, Super Hornets, and of course the F-35, which fields the most complete IR sensor suite of any fighter. The F-35 has a stealthy, built-in IRST that doubles as a targeting pod. (&lt;a href=&quot;//youtu.be/L2q65qOl1tM?t=42&quot; rel=&quot;noreferrer&quot;&gt;Demo&lt;/a&gt;.) Its DAS also allows pilots to see in a complete sphere (4 pi steradian) around the a/c, even through the floor and headrest (no blindspots); its primary function is missile approach and warning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35 is an important example here because it'll soon comprise the backbone of NATO aviation for decades. Some 3,400 F-35s are slated for production, more than all F-15s, Super Hornets, Rafales, Gripens, Eurofighters, and Su-27s produced to date &lt;em&gt;combined&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Btw, if you're skeptical about the F-35 -- kinematics (speed, dogfighting v. F-16), range, stealth, weapons (gun), software, cost -- I'll direct you to these &lt;a href=&quot;//aviation.stackexchange.com/questions/25312/if-all-fighter-jets-become-stealthy-how-will-they-fight-each-other-in-the-futur/25319?noredirect=1#comment60734_25321&quot;&gt;two&lt;/a&gt;..&lt;a href=&quot;//aviation.stackexchange.com/questions/25312/if-all-fighter-jets-become-stealthy-how-will-they-fight-each-other-in-the-futur/25319?noredirect=1#comment60735_25321&quot;&gt;comments&lt;/a&gt; on kinematics, &lt;a href=&quot;//comprehensiveinformation.blogspot.com&quot; rel=&quot;noreferrer&quot;&gt;this compendium&lt;/a&gt;, and &lt;a href=&quot;//reddit.com/r/F35Lightning&quot; rel=&quot;noreferrer&quot;&gt;this community&lt;/a&gt;. (To start, a fully loaded F-35 with 5k lbs weapons accelerates like a clean F-16 and &lt;a href=&quot;//youtu.be/aWji8AcOYGA&quot; rel=&quot;noreferrer&quot;&gt;points its nose like a Hornet&lt;/a&gt;.) If you're still skeptical, I can start another 30,000 character post.)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: Stealth makes you invisible to radar&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Not quite.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stealth vastly reduces your RCS, but does not completely erase it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VLO a/c are much, much harder to detect and track. Active radar detection range goes with RCS&lt;sup&gt;1/4&lt;/sup&gt;. So a 10x reduction in RCS roughly halves detection range. [See &lt;a href=&quot;//en.wikipedia.org/wiki/Radar#Radar_equation&quot; rel=&quot;noreferrer&quot;&gt;radar equation&lt;/a&gt;.] &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, an F-22 or F-35 has an RCS of 0.0001 m&lt;sup&gt;2&lt;/sup&gt;. A clean [unarmed] F-16 has an X-band RCS of about 2 m&lt;sup&gt;2&lt;/sup&gt;. &lt;strong&gt;The F-22/35 will be detected at 12-22x shorter ranges than the F-15/16&lt;/strong&gt;---effectively under 5-10 miles when using a fighter-class radar. That's almost close enough to see [see note] and certainly within IRST range.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Platform | RCS m^2 | 1/range | Detection range&#xA;=========|=========|=========|==================&#xA; F-15    | 25      |  1.0    | 100.&#xA;Su-27    | 15      |  1.1    |  88.&#xA; F-16C   |  1.2    |  2.1    |  47.&#xA; F-18    |  1      |  2.2    |  45.&#xA;Rafale   |  1      |  2.2    |  45.&#xA;Typhoon  |   .5    |  2.6    |  38.&#xA;Bird     |   .01   |  7.1    |  14.&#xA;Insect   |   .001  | 13      |   8.0&#xA; F-22    |   .0001 | 22      |   4.5&#xA; F-35    |   .0001 | 22      |   4.5&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(RCS values are ballpark figures for &lt;em&gt;clean&lt;/em&gt; aircraft. External stores greatly increase RCS. A typical F-16 loadout for permissive environments (eg, ISIS, COIN) includes 2x 370 gal fuel tanks, 2x 2000 lb JDAMs (or equivalent), 2x AMRAAMs, 1x Sniper targeting pod. 2x AMRAAMs, 2x AIM-9s, a nav pod (eg LANTIRN), and an ECM pod may be added in more challenging environments. Like &lt;a href=&quot;https://i.stack.imgur.com/Gc2KK.jpg&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;. Not like &lt;a href=&quot;https://i.stack.imgur.com/SYxlF.jpg&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;. Exception: F-22 and F-35, which carry their stores internally in high threat environments.)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Note that visual range is theoretically up to 20 miles. But in 99.9% of real life cases it's &amp;lt;5 miles. Often just 2-4 miles.]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that once loaded with fuel and weapons, the F-16 and F-15 have much larger RCS values, so will be detected from even further out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, while we no longer use large faceted designs (see: F-117) thanks to modern computing, we still shape our a/c to direct radar energy in certain directions away from the transmitter -- mostly to the sides and above -- in narrow lobes or &quot;spikes.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;//youtu.be/u-cfy-k_8ew?t=2371&quot; rel=&quot;noreferrer&quot;&gt;Illustration (video)&lt;/a&gt;. Skunkworks engineer discusses designing stealth. Listen closely.&#xA;Screencap:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9LGGh.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9LGGh.png&quot; alt=&quot;fuzzball&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placeholder: once detect radar transmitter, stay out of detection range. Because detection range is so short, you have a lot more elbow room than non-stealthy fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, you're not invisible to radar, but operationally, it's much easier to remain undetected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placeholder: B-2 spike management. mission planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nNGNQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nNGNQ.jpg&quot; alt=&quot;gap&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: Stealth is obsolete / stealth is a hoax / stealth is marketing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;LO remains relevant (and very useful) for the same reason armor didn't become obsolete when antitank guided missiles were fielded. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;LO also makes jamming far more efficient. Jamming basically hides your aircraft's 25 m&lt;sup&gt;2&lt;/sup&gt; RCS. If your RCS is only 0.0001 m&lt;sup&gt;2&lt;/sup&gt;, it takes far less power to hide yourself, and your jamming will work at far greater range. &lt;a href=&quot;//youtu.be/d5T1vPmA-l4?t=6m27s&quot; rel=&quot;noreferrer&quot;&gt;Primer: how jamming works&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LO technologies drastically reduce detection ranges and warning times. Sensors that work well against stealthy aircraft would work &lt;em&gt;far better against non-stealthy aircraft.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the alternative to stealth? No stealth? Make our aircraft &lt;em&gt;easier&lt;/em&gt; to detect and track?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All future combat a/c designs must consider signature reduction going forward---at the very least &lt;em&gt;some&lt;/em&gt; signature reduction, if not outright VLO designs---camouflaged tanks are always more desirable than this (or &lt;a href=&quot;//i2.cdn.turner.com/cnn/2012/images/10/19/pinkm60.jpg&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt;):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/GsnYP.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GsnYP.png&quot; alt=&quot;breast cancer awareness&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: WWII radars / low-frequency radars make stealth obsolete / an F-117 was shot down by an 1960s radar with simple modifications&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;First, the F-117 story is untrue&lt;/strong&gt;. The Serbs claimed they made simple modifications to their old Soviet radars, allowing them to easily spot the F-117s. But &lt;a href=&quot;//en.wikipedia.org/wiki/Zolt%C3%A1n_Dani&quot; rel=&quot;noreferrer&quot;&gt;Zoltán Dani&lt;/a&gt;, the Serbian commander who shot down the F-117 in Kosovo, later admitted on national TV that he never modified the radars, merely used the lowest frequency setting. He explained that he fabricated his story for propaganda. Others alleged he did it to take [more] credit for shooting down the F-117. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, NATO jamming support was unavailable the night the F-117 was shot down. Dani was aware, so he turned his radars on a third time without relocating, which allowed him to obtain the fateful radar lock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But more importantly (and accurately) the F-117 was shot down because of lazy mission planning by the US. The F-117 flew the same route night after night at roughly the same hours. So the Serbs moved their radars directly beneath the anticipated flight path. After a number of attempts were made over several nights, they finally got a lock at just 8 mi (13 km) when the bomb bay doors opened. The F-117 doesn't have a radar warning receiver---the pilot never knew he was directly overflying a SAM radar site (doable, but still ill-advised for any stealth fighter). He only ejected because he visually spotted the missile heading for him.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;People forget the F-117 is an old design. It entered service in 1983, just five years after the F-16 and nine years after the F-14. Back then, we didn't know how to integrate radars and other apertures into the skin without compromising its low signature. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be clear, a kill is a kill, and Dani deserves credit. People also forget that the Serbian forces were motivated, competent, and well-trained---measurably more so than Saddam's air defenses. The Serbs performed much better than the Iraqis and learned much from the lessons of Desert Storm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-117 was only shot down once in its entire career, despite regularly flying into some of the most heavily defended airspace in the world, a feat no other platform could perform without &lt;a href=&quot;//aviation.stackexchange.com/a/21258/7394&quot;&gt;massive support (expensive!)&lt;/a&gt;... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QGbs8.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QGbs8.png&quot; alt=&quot;(value of stealth&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...or &lt;a href=&quot;//aviation.stackexchange.com/a/21258/7394&quot;&gt;massive losses&lt;/a&gt; (save the B-2, F-22, F-35). Stealth alone allowed the F-117 to survive. Even F-15s and Su-35s would have been shot down in droves if we sent them on the same missions alone. (Image &lt;a href=&quot;https://higherlogicdownload.s3.amazonaws.com/AFA/def574d3-a429-454b-a3e8-e5073c93ca6b/UploadedImages/MI%20DD%20Bomber%20final.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Second, low-frequency radars have several drawbacks:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;extremely large and power hungry, suitable only for ground-based platforms, not fighters. Some are vehicle-based, but as so large, they're only semi-mobile&lt;/li&gt;&#xA;&lt;li&gt;require large apertures to function, owing to their long wavelengths&lt;/li&gt;&#xA;&lt;li&gt;easiest to spoof &lt;/li&gt;&#xA;&lt;li&gt;easy to detect from long range&lt;/li&gt;&#xA;&lt;li&gt;detection range is grossly over-advertised&lt;/li&gt;&#xA;&lt;li&gt;resolution is terrible (on the order of kilometers), making them unsuitable for targeting.&lt;/li&gt;&#xA;&lt;li&gt;the most straightforward countermeasure to low-freq radars is to make aircraft larger. So VLO bombers (large a/c) are far less detectable by low-freq radars&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(Principal: long wavelengths approach the feature size on aircraft, like tails, so shaping is less effective in redirecting radar returns)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;all the above make them easy targets for long-range weapons like cruise missiles. &lt;/li&gt;&#xA;&lt;li&gt;for all the above reasons, they're usually used as early warning radars or to cue higher-frequency radars.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;High frequency radars are suitable for targeting, are more jam resistant, and are smaller/lighter. That's why fighters are optimised for stealth at higher frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Analogy: you can &lt;em&gt;hear&lt;/em&gt; a fly buzzing around your room &lt;em&gt;somewhere&lt;/em&gt; (detection), but you must &lt;em&gt;see&lt;/em&gt; it to swat it (higher resolution sensor for weapons quality track). You can use your ears to cue your eyes, but you'll never hit it with your eyes closed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6E4xY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6E4xY.jpg&quot; alt=&quot;LO v RF&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Lo-freq on left, hi-freq on right. SMSgt Mac, elementsofpower.blogspot.com)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: WVR combat / dogfighting is the primary arena of aerial combat&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;First, WVR combat =/= dogfighting =/= guns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second...&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Myth: Guns are the primary weapons of aerial combat. F-4's were massacred by obsolete MiG-21s in Vietnam because they didn't have guns.&lt;/h2&gt;&#xA;&#xA;&lt;h3&gt;Common F-4 myth&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;When Vietnam started, USAF and Navy F-4's claimed just a 2:1 kill/loss ratio. Here commentators often blamed malfunctioning missiles and lack of a gun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the USAF added a gun to the F-4, but their K/L remained at 2:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast, the Navy began a new program to better train pilots how to use their missiles. They also trained the maintenance crews how to properly handle and maintain their missiles. They did not add a gun.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By war's end, the &quot;sluggish&quot; Navy F-4's claimed a 12:1 K/L ratio against its more maneuverable adversaries like the &quot;agile&quot; MiG-21.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That training program? It became TOPGUN. (&lt;a href=&quot;//sandiegomagazine.com/San-Diego-Magazine/October-2009/Top-Gun-40-Years-of-Higher-Learning/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;h3&gt;Welcome to the BVR missile era&lt;/h3&gt;&#xA;&#xA;&lt;p&gt;The last fighter v. fighter guns kill was in 1989, an Iranian F-4E shooting down an Iraqi Su-22 (&lt;a href=&quot;//csbaonline.org/publications/2015/04/trends-in-air-to-air-combat-implications-for-future-air-superiority/&quot; rel=&quot;noreferrer&quot;&gt;CSBA&lt;/a&gt;). The F-35's gun is largely for air to ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vast majority of kills over the last 40 years were achieved with missiles:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lhIDl.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lhIDl.png&quot; alt=&quot;csba kills&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Global, fixed-wing v fixed wing. &quot;Other&quot; includes things like CFIT and flying into your own drop tanks. &lt;a href=&quot;//csbaonline.org/publications/2015/04/trends-in-air-to-air-combat-implications-for-future-air-superiority/&quot; rel=&quot;noreferrer&quot;&gt;CSBA&lt;/a&gt;. See pg 24, pg 36 of 76). &lt;a href=&quot;//redd.it/3x3dpy&quot; rel=&quot;noreferrer&quot;&gt;Annotation&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1960s, guns still dominated. Most gun kills were achieved by Israelis; they used guns exclusively because no one would sell them missiles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, by the 1970s, missiles accounted for more kills than guns. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in Vietnam, the AIM-7 Sparrow missile accounted for more kills than any other weapon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5mOXa.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5mOXa.png&quot; alt=&quot;nam aim7&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;North Vietnam &lt;em&gt;also&lt;/em&gt; favored missiles for the balance of its air to air kills, especially as the war progressed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Desert Storm, most shots were fired from BVR. Few air to air engagements required any significant maneuvering at all. Only two air to air guns kills were claimed: A-10s vs helos. In another engagement, a helo was destroyed by a laser-guided bomb. In other words, &quot;A2A&quot; bombs killed nearly as many a/c as guns in the Gulf War. Iraq also lost 3 a/c to CFIT.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And yes, we make &lt;strong&gt;supremely&lt;/strong&gt; better missiles today.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Early AAMs were more akin to guided cannon shells: narrow field of view, short range, and low maneuverability; often only chased a target in front of them (tail chase).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern AAMs (HOBS, LOAL) have comparatively stupendous ranges: a modern SRAAM (188 lb AIM-9X Sidewinder) has roughly the range of the original AIM-7 Sparrow (a much larger 500 lb MRAAM); and the new AIM-120D AMRAAM (335 lb MRAAM) has nearly the range of the legendary AIM-54 Phoenix (1000 lb LRAAM).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will not easily outrun a Mach 3 missile pulling 50 g's with a 200° field of view. Why turn 720° when you can &lt;a href=&quot;//youtu.be/6YMSfg26YSQ&quot; rel=&quot;noreferrer&quot;&gt;shoot almost directly behind you? (video of AIM-9X testing, 2000)&lt;/a&gt;. (Realistically, some level of maneuverability is required for good shots, but far less than for a guns solution.) &lt;a href=&quot;//redd.it/42nst8&quot; rel=&quot;noreferrer&quot;&gt;More videos, gifs, gfys, and MICA.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reliability. In ODS: shot 28 AIM-7s at BVR, 22 hit the target or fireball; 10x more reliable than AIM-7s in Vietnam.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, missiles are now far better dogfighters than fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the best dogfighting weapon &lt;em&gt;by far&lt;/em&gt; is neither gun nor missile: it's a wingman. Fighters don't fly alone. When you dogfight, A) you rapidly bleed speed and altitude, and B) your SA evaporates because you can't afford to focus on anything else except the guy you're turning with. You're effectively a sitting duck and blind, an easy target for anyone outside the fight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dogfighting is extremely dangerous. Two modern fighters are liable to both die in a dogfight, ie a kill/loss ratio of 1:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know of no pilot who prefers dogfighting over taking BVR shots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dogfighting may not be dead. But it sure is on life support.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Resources&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//csbaonline.org/publications/2015/04/trends-in-air-to-air-combat-implications-for-future-air-superiority/&quot; rel=&quot;noreferrer&quot;&gt;CSBA: Trends in Air-to-Air Combat: Implications for Future Air Superiority&lt;/a&gt; --- essential reading&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://higherlogicdownload.s3.amazonaws.com/AFA/6379b747-7730-4f82-9b45-a1c80d6c8fdb/UploadedImages/Mitchell%20Publications/The%20Radar%20Game.pdf&quot; rel=&quot;noreferrer&quot;&gt;The Radar Game&lt;/a&gt; --- Radar and stealth primer. Requisite reading.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//radartutorial.eu/index.en.html&quot; rel=&quot;noreferrer&quot;&gt;RadarTutorial.eu&lt;/a&gt; --- radar tutorial. How radars work. Very useful explanations. Explains some of the limitations/necessities of targeting/guidance.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//redd.it/3cbgs5&quot; rel=&quot;noreferrer&quot;&gt;Gulf War Air Power Survey (GWAPS)&lt;/a&gt; --- how the Gulf War air campaign was fought (these are some of my notes; the entire report is ~3500 pg).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//amazon.com/War-With-Iraq-Critical-Lessons/dp/0972911707&quot; rel=&quot;noreferrer&quot;&gt;War with Iraq: Critical Lessons&lt;/a&gt; --- General Glosson's book on the war (he orchestrated and designed the campaign) and &quot;explains the deeper strategy and thinking behind the air campaign&quot;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//redd.it/28li26&quot; rel=&quot;noreferrer&quot;&gt;A great selection of books on ODS&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//books.google.ca/books/about/Air_warfare_in_the_missile_age.html?id=voLfAAAAMAAJ&amp;amp;redir_esc=y&quot; rel=&quot;noreferrer&quot;&gt;Air Warfare in the Missile Age&lt;/a&gt; by Lon Nordeen. Covers every major conflict from 1965 to 2003.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//redd.it/3if7ss&quot; rel=&quot;noreferrer&quot;&gt;Modern aerial warfare and doctrine&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//globalsecurity.org/military/world/stealth-aircraft-rcs.htm&quot; rel=&quot;noreferrer&quot;&gt;RCS values on Global Security&lt;/a&gt;. Note that the F-35 values were estimates from early in the JSF program, before any production airframes were built. After the F-35 had been built, flown, and tested, officials from the test program (including a pilot) went on record saying the F-35 was actually stealthier than the F-22.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;//redd.it/3u2oml&quot; rel=&quot;noreferrer&quot;&gt;Resources I most frequently recommend&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Glossary:&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;1&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;AAM - air to air missile&lt;/li&gt;&#xA;&lt;li&gt;a/c - aircraft&lt;/li&gt;&#xA;&lt;li&gt;Allied Force - NATO bombing of Yugoslavia, Kosovo War&lt;/li&gt;&#xA;&lt;li&gt;HOBS - high off-boresight - describing very agile missiles with a wide field of view&lt;/li&gt;&#xA;&lt;li&gt;LOAL - lock-on after launch&lt;/li&gt;&#xA;&lt;li&gt;ODS - Operation Desert Storm, part of the Gulf War&lt;/li&gt;&#xA;&lt;li&gt;RCS - radar cross section&lt;/li&gt;&#xA;&lt;li&gt;RF - radio freq&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;2&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;EO - electro-optical (&quot;telescope&quot;)&lt;/li&gt;&#xA;&lt;li&gt;EOST - &quot; &quot;&lt;/li&gt;&#xA;&lt;li&gt;IRST - IR search and track (&quot;IR telescope&quot;)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;3&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;SR - short range&lt;/li&gt;&#xA;&lt;li&gt;MR - medium range&lt;/li&gt;&#xA;&lt;li&gt;LR - long range&lt;/li&gt;&#xA;&lt;li&gt;VLR - very long range&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;4&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;BVR - beyond visual range&lt;/li&gt;&#xA;&lt;li&gt;WVR - within visual range&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;5 &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LO - low observable - (&quot;stealth&quot;) a broader term, sometimes interchangeable with VLO&lt;/li&gt;&#xA;&lt;li&gt;VLO - very low observable - ascribed to only &quot;true&quot; stealth platforms - eg, F-117, B-2, F-22, F-35&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(30,000 character limit exceeded)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placeholder: kinematics still matter&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placeholder: Alleged flaw: &lt;code&gt;Dogfights are more common if US fought USSR instead of easy foes.&lt;/code&gt; Why would an adversary with better, longer-ranged sensors and weapons want to get closer where he is also more vulnerable? Related: &lt;code&gt;Combat between peers results in dogfights.&lt;/code&gt; Most kills during the 80s resulted from the 8-year Iran-Iraq war between pretty evenly matched opponents. &lt;a href=&quot;https://i.stack.imgur.com/lhIDl.png&quot; rel=&quot;noreferrer&quot;&gt;Missiles still dominated.&lt;/a&gt; Related: &lt;code&gt;Comparison isn't fair; US had better tech.&lt;/code&gt; That's the point. Don't want to fight fair. If high-tech produces fantastic victories, then high-tech sounds like a good idea.&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2016-12-25T12:48:06.267" LastActivityDate="2016-12-25T12:48:06.267" CommentCount="31" ContentLicense="CC BY-SA 3.0" />
  <row Id="25328" PostTypeId="2" ParentId="25324" CreationDate="2016-02-17T04:28:43.837" Score="4" Body="&lt;p&gt;Yes, the wing is positioned so that the center of lift is near the center of gravity. The MD-80 is very tail heavy due to the aft mounting of the engines. I have actually personally seen the nose of an MD-80 lifted off the ground by a jet bridge, and it didn't even hurt the door that was supporting the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This chart is from the MD-80 weight and balance manual, which can be found on google. You can see that the center of gravity (CG) must be within -2.8% to 33.4% of the Mean Aerodynamic Chord (MAC) which is an approximation of average wing chord. So basically the CG must be in the forward 1/3 of the average wing chord, typically the center of lift is around 25% of chord. On the MD-80 the leading edge of the MAC is at body station 885.547, which is behind the actual LE of the wing at the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6ilfb.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6ilfb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason you want to place the CG near the center of lift is to create the smallest pitch moment possible between the CG and CL. The pitching moment created by the difference in the CG and CL location must be reacted out by the horizontal stabilizer. The more moment, the larger the stabilizer must be and the more inefficient the aircraft. Here is an illustration (stolen from this question &lt;a href=&quot;https://aviation.stackexchange.com/questions/16307/how-does-a-commercial-airliner-measure-its-weight-mass&quot;&gt;How does a commercial airliner measure its weight/mass?&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ABobH.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ABobH.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the picture of the MD-80 doing the wheelie:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lpWCw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lpWCw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-02-17T15:58:12.027" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25329" PostTypeId="1" AcceptedAnswerId="25344" CreationDate="2016-02-17T04:55:13.450" Score="6" ViewCount="684" Body="&lt;p&gt;I'm designing an airport of a flight simulator. One of the runway settings is &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway_end_identifier_lights&quot; rel=&quot;nofollow&quot;&gt;Runway End Identifier Lights&lt;/a&gt; (REIL). Is there a way I can see if a runway at a US airport has &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/lsg/reil/&quot; rel=&quot;nofollow&quot;&gt;REIL&lt;/a&gt; via the internet, and whether they are Omnidirectional or Unidirectional REIL?&lt;/p&gt;&#xA;" OwnerUserId="13558" LastEditorUserId="12720" LastEditDate="2016-02-17T22:23:06.930" LastActivityDate="2016-02-17T22:32:34.077" Title="How do I know if a runway has REIL?" Tags="&lt;airport-lighting&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25332" PostTypeId="2" ParentId="25280" CreationDate="2016-02-17T05:10:40.693" Score="1" Body="&lt;p&gt;Not completely sure what you are asking. But in a tail dragger aircraft the center of gravity (CG) is behind the main land gear (MLG), while a tricycle configuration places the CG in front of the MLG. You achieve this by placement of the MLG, tail draggers generally have their MLG mounted near or forward of the lending edge of the wing, while tricycles' MLG are placed toward the middle or aft part of the wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course moving the landing gear around will move the empty CG of the aircraft and a tricycle configuration will generally weigh more. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many kit planes that allow you to build the aircraft either way, but I don't know any that would allow an easy conversion from one to the other. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2016-02-17T16:01:00.337" LastActivityDate="2016-02-17T16:01:00.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25333" PostTypeId="2" ParentId="25309" CreationDate="2016-02-17T06:48:48.727" Score="3" Body="&lt;p&gt;Uk CAA CAP493 Section 3 Chapter 1 Paragraph 11.4 states :&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the case of a departure ATIS, controllers must obtain a read-back of all relevant altimeter settings contained in the broadcast, unless the setting will also be passed in association with start-up or taxi clearance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So from the point of view of the controller you are doing a good thing because you are saving him the expense of having to confirm that you have the right QNH on board.&lt;/p&gt;&#xA;" OwnerUserId="7214" LastActivityDate="2016-02-17T06:48:48.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25334" PostTypeId="2" ParentId="25323" CreationDate="2016-02-17T07:02:58.827" Score="3" Body="&lt;p&gt;The airport is buying fuel and selling to airlines. And more over, they provide different types of fuel on prior request by the airliner. Reference : &lt;a href=&quot;http://www.airport.lk/AIS/PDF/A8.pdf&quot; rel=&quot;nofollow&quot;&gt;VCBI&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13562" LastEditorUserId="12220" LastEditDate="2016-02-17T13:37:49.173" LastActivityDate="2016-02-17T13:37:49.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25335" PostTypeId="2" ParentId="25295" CreationDate="2016-02-17T07:07:14.173" Score="1" Body="&lt;p&gt;Those are cargo and baggages. Yes passenger flights do transport cargo other than baggages. &lt;/p&gt;&#xA;" OwnerUserId="13562" LastActivityDate="2016-02-17T07:07:14.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25336" PostTypeId="1" CreationDate="2016-02-17T07:10:34.687" Score="4" ViewCount="1391" Body="&lt;p&gt;I believe that all aircraft must be controlled under ATC's instructions to fly safely especially when take-off and landing. And, most ATC instructions are conducted by ground radar which controllers use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I know that the stealth aircraft (including B-2, F-22 etc.) aren't captured on radar display owing to their stealth ability. If so, how does a controller give instructions like radar vectors to stealth aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that there's are primary and secondary target when using radar, and the controller must use primary target to vector aircraft. I guess stealth aircraft can be captured by secondary radar but not primary target.&lt;/p&gt;&#xA;" OwnerUserId="13563" LastEditorUserId="595" LastEditDate="2016-02-17T09:10:19.493" LastActivityDate="2016-02-18T01:18:44.577" Title="How do stealth aircraft get ATC?" Tags="&lt;air-traffic-control&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25337" PostTypeId="2" ParentId="25336" CreationDate="2016-02-17T07:14:20.500" Score="1" Body="&lt;p&gt;ATC concept is based on cooperative targets (i.e. willing to send their position to the ATC radar). I suppose that they are equipped on board with a transponder that is switched on when there is a need for air control. &lt;/p&gt;&#xA;" OwnerUserId="7214" LastActivityDate="2016-02-17T07:14:20.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25338" PostTypeId="2" ParentId="25336" CreationDate="2016-02-17T08:11:47.410" Score="8" Body="&lt;p&gt;The concept of ATC is based on primary radar targets, secondary radar targets and radio communication being used to determine the position of aircraft and establish separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept of stealth aircraft is to reduce production of primary radar targets and being able to turn off transponders to disable secondary radar targets being visible. Stealth aircraft also do not communicate on frequencies during tactical missions, they are designed and meant to reduce radio emission to enable the stealth features.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they are not on a tactical mission and stealth is not required, they will simply turn on their transponders and communicate with ATC on the required frequencies.&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2016-02-17T13:53:24.547" LastActivityDate="2016-02-17T13:53:24.547" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25339" PostTypeId="1" AcceptedAnswerId="25345" CreationDate="2016-02-17T08:58:46.047" Score="11" ViewCount="1487" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/25312/if-all-fighter-jets-become-stealthy-how-will-they-fight-each-other-in-the-futur&quot;&gt;this question&lt;/a&gt;, Hephaestus Aetnaean posted the following cool movie:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/v5VuCsQJy8Y?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which showed the following still:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iKDE1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iKDE1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As indicated by the red circles (the yellow marking can be ignored) there seem to be a few hotspots visible on the IR image. What are these hotspots? They seem to be rather random, so I'm not sure what they exactly are.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="14897" LastEditDate="2019-09-15T13:44:44.690" LastActivityDate="2019-09-15T13:44:44.690" Title="What are these thermal spots on this infrared image of an F-16?" Tags="&lt;fighter&gt;&lt;f-16&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25342" PostTypeId="2" ParentId="25280" CreationDate="2016-02-17T14:48:16.623" Score="2" Body="&lt;p&gt;There are some planes out there that exist in both configurations. One of the more common and first that comes to mind is the popular &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_150&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 150&lt;/a&gt;, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 172&lt;/a&gt; also has an available conversion. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a taildragger&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R0bcr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R0bcr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/e/e5/Cessna150taildraggerC-GOCB02.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And with tricycle gear &#xA;&lt;a href=&quot;https://i.stack.imgur.com/6cRt3.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6cRt3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.mata-usa.org/wp-content/uploads/2012/02/003-e1331767896577.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the majority of the mass remains unmoved (the engine, fuel tanks etc) the CG will see a bit of a shift but will not be that drastic. The biggest weight shift will be moving the mains up front. However since your gear is located in a different place and thus is loaded differently your CG limits may change.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-02-17T14:48:16.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25343" PostTypeId="2" ParentId="25336" CreationDate="2016-02-17T15:29:20.163" Score="7" Body="&lt;p&gt;&lt;strong&gt;&lt;em&gt;First off:&lt;/em&gt;&lt;/strong&gt;&lt;Br&gt;&#xA;&lt;em&gt;&quot;I believe that all aircraft must be controlled under ATC's instructions to fly safely especially when take-off and landing.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not true.   When I fly my small Cessna from an untowered airport in VFR conditions, I don't file a flight plan, and I don't talk to ATC.  I do make annoucments on the CTAF, but that is not even required.   I would be completely legal to take off, fly and land, never turning on my radio or talking to anyone.  &lt;strong&gt;&quot;See-and-avoid&lt;/strong&gt; is the rule.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Secondly:&lt;/em&gt;&lt;/strong&gt;&lt;Br&gt;&#xA; Stealth aircraft are stealthy only when they are trying to be.  Something as simple as lowering the landing gear would provide a strong radar return.  The transponder can indicate position, ADS-B can provide precise updates, and the pilot can verbally describe their position to ATC.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-02-17T15:29:20.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25344" PostTypeId="2" ParentId="25329" CreationDate="2016-02-17T15:51:10.073" Score="4" Body="&lt;p&gt;You can find this information in the Airport Facility Directory which is published in print by the FAA and is available &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/search/&quot; rel=&quot;nofollow noreferrer&quot;&gt;for free from them online here&lt;/a&gt;. REIL will be listed for the specific runway for the airport in question. For example I fly out of KDYL and if we take a look at the page in the AFD for KDYL you will see REIL listed for RWY 23&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9bPEX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9bPEX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://aeronav.faa.gov/afd/04feb2016/ne_259_04FEB2016.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="12720" LastEditDate="2016-02-17T22:32:34.077" LastActivityDate="2016-02-17T22:32:34.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25345" PostTypeId="2" ParentId="25339" CreationDate="2016-02-17T16:59:51.493" Score="16" Body="&lt;p&gt;In &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/c/c3/F-16_Nose_and_Cockpit_Side_View_in_Songshan_Air_Force_Base_20110813.jpg&quot; rel=&quot;noreferrer&quot;&gt;this picture&lt;/a&gt; from Wikipedia it can be clearly seen that the two along the bottom of the fuselage are both heated air data probes, as Federico pointed out. &lt;a href=&quot;https://aviation.stackexchange.com/q/24773/1696&quot;&gt;The probes are heated&lt;/a&gt; to prevent ice from forming and blocking air flow to the sensors. The forward one is a pitot probe, and the aft one is a &lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?t=3415&quot; rel=&quot;noreferrer&quot;&gt;total temperature probe&lt;/a&gt;. The AOA sensor can also be seen as a much smaller hot spot above the forward pitot probe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I agree with Ron Beyer that the top area is probably the sun reflecting off of the canopy. The lower area is probably a sun reflection as well, off of the external fuel tank. You can see in the video that these areas are not always visible, and move as the F-16 flies past, consistent with a reflection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/txxpE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/txxpE.jpg&quot; alt=&quot;F-16 nose with areas circled&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-02-18T20:44:52.763" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25346" PostTypeId="2" ParentId="25339" CreationDate="2016-02-17T17:03:03.727" Score="-4" Body="&lt;p&gt;I believe what you are seeing is the infrared image picking up heat sources. As the plane flies through the air friction is caused with any object sticking out from the skin of the aircraft. The nose of the aircraft has a Pitot tube which by design sticks out in the airstream. This causes a lot of friction. Additionally the pitot tube is heated to prevent ice from clogging the tube. As for the other spots, I am unsure as to the devices but they appear to be in the airstream as well. Perhaps some are small antennas.&lt;/p&gt;&#xA;" OwnerUserId="8774" LastActivityDate="2016-02-17T17:03:03.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25347" PostTypeId="2" ParentId="1446" CreationDate="2016-02-17T17:04:00.207" Score="3" Body="&lt;p&gt;&lt;a href=&quot;http://www.lufthansa-technik.com/landing-gear-overhaul&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; would lend a number of roughly 240 landings per set of tires &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;an A340 will complete roughly 6,000 take-offs and landings, calling&#xA;  for about 25 sets of replacement tires&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since some aircraft tires can be remolded and to a large extent recycled they are a fairly decent part. In the end of the day the tires are sacrificial by design, its simply easier and cheaper to replace tires every 240 landings than maintain some complex spin up system or use some pricey material (which may or may not exist) that wears slower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In response to this half of the question &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Before landing, why not have a small motor assembly on the landing&#xA;  gear to spin up the tires to the correct speed? Surely this would&#xA;  avoid the degrading tire burn. The tire might last a lot longer and&#xA;  might even offset the cost of the motor assembly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Take a look at &lt;a href=&quot;https://aviation.stackexchange.com/questions/16661/how-are-forces-on-the-landing-gear-reduced-or-compensated-for-at-touchdown/16664#16664&quot;&gt;this similar question&lt;/a&gt; but basically in short there are a few issues with pre spinning tires even if the system was viable from a weight standpoint. They did some research on it back in the day and found that pre spinning does not really reduce wear significantly (more on that in the linked answer).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-02-17T17:04:00.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25348" PostTypeId="2" ParentId="25208" CreationDate="2016-02-17T19:50:57.970" Score="2" Body="&lt;p&gt;Stage length is basically the average length of the flight (see mins' answer for a specific definition).  Average stage length is important because it greatly effects the maintenance and fuel costs for the airplane.  The shorter the stage length, the higher your overall costs will be for the operation of the airplane (and vice-versa, of course).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to estimate the stage length, the following information is needed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Routes which will be flown&lt;/li&gt;&#xA;&lt;li&gt;Performance information for the aircraft&lt;/li&gt;&#xA;&lt;li&gt;Average winds which will be encountered during the flights&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The 85% most likely refers to the Boeing 85% wind data, which is proprietary data produced and sold by Boeing and includes world-wide wind and temperature data at various flight levels and seasons, with statistical reliability between 50% and 99%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that the wind values which are used for the stage length calculation will result in a flight time equal to or better than the result 85% of the time.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-02-17T22:47:36.957" LastActivityDate="2016-02-17T22:47:36.957" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25349" PostTypeId="1" AcceptedAnswerId="25350" CreationDate="2016-02-17T20:19:49.307" Score="7" ViewCount="8854" Body="&lt;p&gt;Both are narrow buildings with aircraft parked on both sides, so what is the main difference?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BeTGa.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BeTGa.png&quot; alt=&quot;terminal&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Airport_terminal#/media/File:Terminal-Configurations.png&quot; rel=&quot;noreferrer&quot;&gt;(image source)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="6886" LastEditDate="2016-02-18T00:39:22.457" LastActivityDate="2019-01-03T09:11:40.890" Title="What is the difference between a concourse and a pier?" Tags="&lt;airport-design&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25350" PostTypeId="2" ParentId="25349" CreationDate="2016-02-17T20:33:59.860" Score="7" Body="&lt;p&gt;In terminal designs, the main difference between a pier and a concourse is that a pier is connected by terminal buildings on one side, but a concourse has separate terminal buildings connected by transportation either under or over ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, the terms &quot;terminal&quot; and &quot;concourse&quot; are often used interchangeably, with &quot;satellite&quot; being used in that specific case, and &quot;piers&quot; being referred to as terminals or concourses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Simple&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small terminal with a few gates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Linear&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer than a simple terminal, with gates on one side. May be curved or straight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Concourses&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standard terminal with gates on one side, with additional linear terminals connected underground or by buses (occasionally by a bridge), each with gates all around. Each is generally designated as a different concourse.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Standard&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A main terminal area, with long extensions having gates down one side. May be designated into different terminals depending on the size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pier&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like concourses, extensions with gates down both sides, but connected on one end by additional buildings. Each pier may be designated as a separate terminal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Satellite&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A main terminal area connected to one or more smaller terminal buildings with gates all around. Generally connected underground, occasionally by a bridge. Each satellite is generally designated a different terminal.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-02-17T20:45:31.003" LastActivityDate="2016-02-17T20:45:31.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25351" PostTypeId="1" AcceptedAnswerId="25352" CreationDate="2016-02-17T21:05:09.450" Score="8" ViewCount="1565" Body="&lt;p&gt;Why was the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_Project_1.44&quot; rel=&quot;noreferrer&quot;&gt;MiG 1.44&lt;/a&gt; so similar to the MBB TKF-90? (for some information on the TKF-90 you have to scroll down &lt;a href=&quot;https://aviation.stackexchange.com/questions/25310/why-do-all-new-european-fighter-jets-have-delta-wings&quot;&gt;this&lt;/a&gt; question, it is the only one source I knew about this particular plane)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the MiG 1.44: &#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/MiG144_left_side.jpg/1280px-MiG144_left_side.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/b/bc/MiG144_left_side.jpg/1280px-MiG144_left_side.jpg&quot; alt=&quot;MiG 1.44&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://commons.wikimedia.org/wiki/Category:Mikoyan-Gurevich_MiG-1.44?uselang=de#/media/File:MiG144_left_side.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the TKF-90&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BYY0s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BYY0s.jpg&quot; alt=&quot;MBB TKF-90 concept&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://aviadejavu.ru/Images6/AK/AK2010-03/36-3.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me, these two aircraft are nearly unrecognizable. They were adversaries in those times, not partners. Has that similarity arised only because of the similar expectations from these airplanes? &lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="1467" LastEditDate="2017-11-17T09:03:27.330" LastActivityDate="2017-11-17T09:03:27.330" Title="Why was the experimental MiG 1.44 so similar to the experimental TKF-90?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25352" PostTypeId="2" ParentId="25351" CreationDate="2016-02-17T22:00:13.213" Score="9" Body="&lt;p&gt;I once led a group of &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov&quot; rel=&quot;noreferrer&quot;&gt;Antonov&lt;/a&gt; engineers through the aircraft exhibition of the &lt;a href=&quot;http://www.deutsches-museum.de/en/flugwerft/information/&quot; rel=&quot;noreferrer&quot;&gt;Deutsches Museum in Unterschleissheim&lt;/a&gt; near Munich. There are two halls connected by a walkway, and from that walkway you can see the restoration workshop which is located between those halls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the group had long left the walkway, one engineer still stood in the middle of it and gazed down at the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dornier_Do_31&quot; rel=&quot;noreferrer&quot;&gt;Dornier Do-31&lt;/a&gt; which at that time stood in the shop for cleaning and repairs after many years in the open. I walked back (with one of our interpreters) and asked him what fascinated him. He said to me that this was the first time he saw this aircraft in person. And he continued that he knows every rivet in it. He had studied it in the early Seventies for several years when Antonov was tasked with developing a VTOL transport aircraft. In the end, they abandoned the idea (like NATO did a few years earlier), but this airplane had been the center of a part of his life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't think bad of this - it is just good engineering practice to study what others have done. If you want to develop something, look what others have done before you and try not to repeat their mistakes. You might as well marvel at the similarities between an &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle&quot; rel=&quot;noreferrer&quot;&gt;F-15&lt;/a&gt; and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Su-27&quot; rel=&quot;noreferrer&quot;&gt;Su-27&lt;/a&gt;, a &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-144&quot; rel=&quot;noreferrer&quot;&gt;Tu-144&lt;/a&gt;, or a &lt;a href=&quot;https://en.wikipedia.org/wiki/Space_Shuttle&quot; rel=&quot;noreferrer&quot;&gt;Space Shuttle&lt;/a&gt; and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Buran_(spacecraft)&quot; rel=&quot;noreferrer&quot;&gt;Buran&lt;/a&gt;. In the end, they were designs made for the same purpose, and it is no wonder that they turned out alike. It just means the engineers did their job properly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In nature this is called &lt;a href=&quot;https://en.wikipedia.org/wiki/Convergent_evolution&quot; rel=&quot;noreferrer&quot;&gt;convergent evolution&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-17T22:04:38.353" LastActivityDate="2016-02-17T22:04:38.353" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25353" PostTypeId="1" AcceptedAnswerId="25355" CreationDate="2016-02-17T23:23:11.973" Score="3" ViewCount="1880" Body="&lt;p&gt;Several pictures of the Concorde taking off, show a cloud of water droplets (fog) above the wings.  Like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5QF22.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5QF22.jpg&quot; alt=&quot;Concorde taking off from Heathrow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume the fog is created due to low pressure over the wings. But, doesn't the size location and visible turbulence of this pattern suggest that the wing is stalled?  It certainly doesn't look like laminar flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't recall seeing this on other aircraft at takeoff.&lt;br&gt;&#xA;What's going on?&#xA;Is it unique to the Concorde?&#xA;Is it exacerbated by ground effect?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://aircraft.wikia.com/wiki/Concorde&quot; rel=&quot;nofollow noreferrer&quot;&gt;This Wikia entry&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the undercarriage had to be unusually strong. This was due to the unusual loadings due to the &lt;strong&gt;high angle of attack that Concorde needed to take-off&lt;/strong&gt; due to its delta-wing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &quot;high angle of attack&quot; would support my guess that the upper wing is stalled?&lt;br&gt;&#xA;I could understand a stall if the aircraft was &lt;em&gt;landing&lt;/em&gt;, but these seem to be near stall during takeoff?&lt;/p&gt;&#xA;" OwnerUserId="3949" LastEditorUserId="3949" LastEditDate="2016-06-05T21:44:46.207" LastActivityDate="2016-06-05T21:44:46.207" Title="Why is the Concorde, and not other aircraft, getting this fog/condensation, over the wing, at *takeoff*?" Tags="&lt;takeoff&gt;&lt;wing&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2016-02-18T06:05:51.843" ContentLicense="CC BY-SA 3.0" />
  <row Id="25354" PostTypeId="2" ParentId="25353" CreationDate="2016-02-17T23:42:54.067" Score="0" Body="&lt;p&gt;You're right to assume low pressure on top of the wing as cause of the condensation. As far as location and turbulence, this would probably have to do with something called &quot;Span Wise Flow&quot; in which air flowing over a wing doesn't just flow straight back, but tends to drive outward towards the wingtips and spill over the edge (a reason for 'winglets'). &lt;/p&gt;&#xA;" OwnerUserId="13541" LastActivityDate="2016-02-17T23:42:54.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25355" PostTypeId="2" ParentId="25353" CreationDate="2016-02-17T23:55:41.523" Score="4" Body="&lt;p&gt;You're correct that the condensation is due to low pressure, but the wing is not stalled. The highly swept delta wing of the Concorde created lift be what is called &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift&quot;&gt;vortex lift&lt;/a&gt;. From my answer in that question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the case of wings having sharp, highly swept leading edges like delta wings, the leading-edge separation vortex phenomenon occurs at subsonic speeds. However, the separation does not destroy the lift as in the case of low sweep wings; instead, it forms two vortices which are (nearly) parallel to the wing edges.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The centre of the vortex is a low pressure region, where condensation forms. In this figure, you can see the vortex formation in a model of Concorde.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/k9Xhu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k9Xhu.jpg&quot; alt=&quot;vortex flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Flow around Concorde in a landing Configuration&lt;/em&gt; by Henri Werlé, ONERA, image from &lt;a href=&quot;http://www.efluids.com/efluids/gallery/gallery_pages/HW011/text.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;efluids.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A side view of the same thing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FS51Y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FS51Y.jpg&quot; alt=&quot;Landing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Flow around Concorde in a landing Configuration* by Henri Werlé, ONERA, image from &lt;a href=&quot;http://www.efluids.com/efluids/gallery/gallery_pages/HW011/text.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;efluids.com&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, basically, the aircraft is still producing lift; only the mechanism is different. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This kind of lift production is quite common in case of highly swept wings. The vortex formation is also found in a number of other cases like &lt;a href=&quot;https://aviation.stackexchange.com/questions/21063/what-advantages-come-with-the-wing-on-the-boeing-bird-of-prey&quot;&gt;chines&lt;/a&gt;, leading edge extensions (like this F-18), etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DBDp2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DBDp2.jpg&quot; alt=&quot;F -18&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Flow visualization over a 1/48-scale model of an F-18 aircraft inside a water tunnel at the Flow Visualization Facility from NASA's Dryden Flight Research Center.&lt;/em&gt; Image from &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:F-18_model_in_water_tunnel_with_dye_injections_%28side_view%29.jpg#/media/File:F-18_model_in_water_tunnel_with_dye_injections_%28side_view%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikimedia commons&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-02-18T00:53:51.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25356" PostTypeId="2" ParentId="25336" CreationDate="2016-02-18T01:18:44.577" Score="-1" Body="&lt;p&gt;They attach radar reflectors so as to be visible to ATC's primary radar. This is in addition to turning on the transponder (secondary radar).&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2016-02-18T01:18:44.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25358" PostTypeId="1" CreationDate="2016-02-18T02:19:42.603" Score="23" ViewCount="3454" Body="&lt;p&gt;I found a quite &quot;rare&quot; layout on Munich airport. It has jetbridges but I don't see any terminal. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nqhPf.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nqhPf.png&quot; alt=&quot;munich&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do passengers make it to this point of the airport? By underground?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-06T21:14:48.243" LastActivityDate="2019-10-23T15:15:23.103" Title="How do passengers board the planes on this airport?" Tags="&lt;airport&gt;&lt;passenger&gt;&lt;ground-operations&gt;&lt;airport-design&gt;&lt;germany&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25359" PostTypeId="2" ParentId="25358" CreationDate="2016-02-18T02:48:18.960" Score="30" Body="&lt;p&gt;They are specially designed apron jet bridges. It looks like the normal gates but required to transfer passenger by bus.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A model shows how it runs (&lt;a href=&quot;http://www.herpa.de/collect/(S(bz1oqv0adphruncjyszpngng))/detail.aspx?productid=520553&amp;amp;express=1&amp;amp;thumb=1&amp;amp;lang=en-GB&quot; rel=&quot;noreferrer&quot;&gt;credit&lt;/a&gt;) :&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aX8gn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aX8gn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2019-10-23T15:15:23.103" LastActivityDate="2019-10-23T15:15:23.103" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25360" PostTypeId="1" CreationDate="2016-02-18T04:19:52.847" Score="8" ViewCount="1432" Body="&lt;p&gt;Are ICAO and FAA airport signs and markings the same or are there differences? If so what are the differences?&lt;/p&gt;&#xA;" OwnerUserId="13577" LastEditorUserId="19" LastEditDate="2016-09-02T09:11:09.427" LastActivityDate="2017-01-10T20:48:16.597" Title="Are ICAO and FAA airport signs and markings the same?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;&lt;runways&gt;&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25361" PostTypeId="2" ParentId="15753" CreationDate="2016-02-18T04:38:27.723" Score="6" Body="&lt;p&gt;A related reason is ensuring safe store separation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of testing is done to ensure your munitions and fuel tanks don't come back to greet you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this doesn't happen: YouTube video of '&lt;a href=&quot;https://www.youtube.com/watch?v=fPTnmZ_HPAs&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Store Separation Incidents&lt;/a&gt;'.&lt;/p&gt;&#xA;&#xA;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The B-1 bomber had a similar issue initially where weapons would not exit the bomb bays and just skip along on the laminar flow underneath the aircraft. They had to add these spoilers to the fronts of the bays to break up the airflow. The spoiler is the waffle iron looking plate in the front. It drops down when the bay is opened for weapon release. &lt;a href=&quot;http://miramar.airshowjournal.com/2005/IMG_0327_2.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://miramar.airshowjournal.com/2005/IMG_0327_2.jpg&lt;/a&gt; - philosoguido - &lt;a href=&quot;https://www.reddit.com/user/philosoguido&quot; rel=&quot;noreferrer&quot;&gt;https://www.reddit.com/user/philosoguido&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The B-2 has similar waffles.&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="556" LastEditDate="2016-02-18T13:30:47.747" LastActivityDate="2016-02-18T13:30:47.747" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25362" PostTypeId="1" CreationDate="2016-02-18T07:33:25.060" Score="0" ViewCount="351" Body="&lt;p&gt;What is the relationship between aircraft thrust and jet exhaust velocity &amp;amp; thrust and mass flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually, my question is how to reduce or decrease jet noise without decreasing the thrust ?&lt;/p&gt;&#xA;" OwnerUserId="13548" LastEditorUserId="595" LastEditDate="2016-02-18T07:48:23.863" LastActivityDate="2016-02-18T11:13:46.680" Title="Relationship Between Aircraft Thrust and Jet Exhaust Velocity?" Tags="&lt;aerodynamics&gt;&lt;general-aviation&gt;&lt;fluid-mechanics&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-02-18T19:48:12.417" ContentLicense="CC BY-SA 3.0" />
  <row Id="25364" PostTypeId="2" ParentId="25362" CreationDate="2016-02-18T11:13:46.680" Score="2" Body="&lt;p&gt;The thrust produced is propotional to the exhaust velocity and mass flow, in simple terms. The thrust equation &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/thrsteq.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;can be written as&lt;/a&gt;,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T$ = $\dot{m}_{e} v_{e} - \dot{m}_{o} v_{o} - (P_{e} - P_{o}) A_{e}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where, $\dot{m}$ is the mass flow rate $v$ is the velocity, $P$ is the pressure and $A$ is the (exhaust) area. The subscripts 'o' and 'e' denote the freestream and exhaust values respectively. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are multiple ways to go about noise reduction in aicraft engines, all with some kind of penalty- the Boeing method is to use chevron shaped exhausts (Interestingly, the type chosen is the &lt;a href=&quot;https://aviation.stackexchange.com/a/19448/9731&quot;&gt;one with lesser thrust penalty&lt;/a&gt;, not the most effective in noise reduction). However, Airbus &lt;a href=&quot;https://aviation.stackexchange.com/questions/24963/why-do-boeing-aircraft-have-serrated-engine-nacelles-but-airbus-does-not/24974#24974&quot;&gt;has cited higher fuel consumption&lt;/a&gt; as the main reason for them not using it. Airbus uses &lt;a href=&quot;https://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjs07__loHLAhXCC44KHfapAPEQFggcMAA&amp;amp;url=http%3A%2F%2Fwww.airbus.com%2Fsupport%2Fpublications%2F%3FeID%3Dmaglisting_push%26tx_maglisting_pi1%255BdocID%255D%3D41153&amp;amp;usg=AFQjCNEOUndjKD87gNLPIzYoun8ptjNkDg&quot; rel=&quot;nofollow noreferrer&quot;&gt;acoustic liners in the engine to reduce noise&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The thrust reverser structure was acoustically treated along approximately&#xA;  half of its internal surface. It was clear that increasing this acoustic area would increase the acoustic sound absorption and hence decrease the overall measurable exhaust noise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-02-18T11:13:46.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25365" PostTypeId="1" CreationDate="2016-02-18T11:51:48.207" Score="1" ViewCount="1180" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Hkmm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Hkmm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;A321neo has on the top of the fin, backwards, a long tube, which looks like the pitot tube on the Boeing 707, but on the opposite way, and connected on it, a cable (I think because it is a test flight).&#xA;What is the purpose of each one?&#xA;Picture's credits: www.airbus.com/presscentre&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="12207" LastEditDate="2016-02-19T16:29:14.020" LastActivityDate="2016-02-19T16:29:14.020" Title="What's the purpose of the cable connected on the top of the fin?" Tags="&lt;airbus-neo&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2016-02-18T13:36:03.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="25366" PostTypeId="2" ParentId="25365" CreationDate="2016-02-18T12:10:47.623" Score="7" Body="&lt;p&gt;It is a Trailing Static or &lt;a href=&quot;https://en.wikipedia.org/wiki/Trailing_cone&quot; rel=&quot;noreferrer&quot;&gt;Trailing Cone&lt;/a&gt; used in test aircraft to measure free stream values. From &lt;a href=&quot;http://www.nasa.gov/centers/dryden/news/DTRS/1995/HTML/TM-104316/index_prt.htm&quot; rel=&quot;noreferrer&quot;&gt;Airdata Measurement and Calibration&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By trailing a long tube behind the airplane, a nearly free-stream static pressure measurement can be taken. A perforated cone at the end of the tube acts as a drag device to keep the tube stable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AHXOV.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AHXOV.gif&quot; alt=&quot;Trailing cone&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.nasa.gov/centers/dryden/news/DTRS/1995/HTML/TM-104316/index_prt.htm&quot; rel=&quot;noreferrer&quot;&gt;NASA Airdata measurement and calibration&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is used in test aircraft. The image below shows the trailing cone attached to the 787 dreamliner (pictured at Paris airshow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vrx8D.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vrx8D.jpg&quot; alt=&quot;787 cone&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.flyingsquadron.com/forums/topic/18306-paris-air-show-2011/?page=2&quot; rel=&quot;noreferrer&quot;&gt;flyingsquadron.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This image shows the trailing cone assembly used in 787 dreamliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bS5A8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bS5A8.jpg&quot; alt=&quot;787 Trailing cone&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://airpigz.com/blog/?currentPage=59&quot; rel=&quot;noreferrer&quot;&gt;airpigz.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The device is specified by FAA and JAA as one of several methods that can be used to perform flight calibrations. According to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2091-85.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Advisory Circular 91-85&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Where precision flight calibrations are used to quantify or verify altimetry system performance they may be accomplished by any of the ollowing methods. ...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Precision tracking radar in conjunction with pressure calibration of &#xA;  atmosphere at test altitude. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Trailing cone.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Pacer aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;• Any other method acceptable to the FAA or approving authority. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-18T12:10:47.623" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25367" PostTypeId="1" AcceptedAnswerId="25428" CreationDate="2016-02-18T13:09:25.260" Score="15" ViewCount="1703" Body="&lt;p&gt;I know that rain generally worsens the aerodynamic propeties of an aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm wondering what processes cause the increase in drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm mostly interested in General Aviation, thus relatively low speed and low altitudes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several things I can imagine, although the effects might be small:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The water in the air makes it heavier, increasing the effective value of the air density, $\rho$&lt;/li&gt;&#xA;&lt;li&gt;Rain might lower the temperature, again having an effect on $\rho$&lt;/li&gt;&#xA;&lt;li&gt;Rain drops on the wing might cause earlier transition on the wing, increasing  drag.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I hope somebody can clarify what magnitude these effects have, and if there are any more effects that cause an increase in drag when flying in the rain.&lt;/p&gt;&#xA;" OwnerUserId="4197" LastEditorUserId="4197" LastEditDate="2016-02-18T19:46:25.547" LastActivityDate="2016-02-20T12:32:20.830" Title="What phenomenon causes the increase of drag with rain?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;drag&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25368" PostTypeId="1" AcceptedAnswerId="25435" CreationDate="2016-02-18T15:12:05.500" Score="12" ViewCount="3738" Body="&lt;p&gt;In Hephaestus Aetnaean's answer to &lt;a href=&quot;https://aviation.stackexchange.com/q/25312/8730&quot;&gt;this question&lt;/a&gt;, it is mentioned that the F-117 had no radar detection equipment because at the time it was developed the designers had not figured out how to integrate the antennas into the body without increasing its radar profile. How is this done on newer stealth aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And what about things like air speed sensors? Do they use something other than a pitot tube?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a related question, obviously if this was the case they apparently were not able to place radar detection inside the cockpit as you can with police radar detectors. Is the cockpit glass in the F-117 somehow opaque to radar or is there another reason?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="15311" LastEditDate="2020-04-26T15:55:14.093" LastActivityDate="2020-04-26T15:55:14.093" Title="How are antennas integrated into stealth aircraft?" Tags="&lt;stealth&gt;&lt;antenna&gt;&lt;f-117&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25369" PostTypeId="1" CreationDate="2016-02-18T15:12:58.163" Score="0" ViewCount="126" Body="&lt;p&gt;If fuel is stored in the wings, which are in constant movement during the flight, can the fuel unbalance the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-02-18T15:35:13.213" Title="Can the fuel on the wing cause the aircraft to destabilize?" Tags="&lt;stability&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-02-18T16:22:50.753" ContentLicense="CC BY-SA 3.0" />
  <row Id="25370" PostTypeId="2" ParentId="25369" CreationDate="2016-02-18T15:30:49.077" Score="1" Body="&lt;p&gt;Yes it can. Source: I'm a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft (even many small general aviation ones) have balance parameters where the fuel quantity in each side cannot/should not exceed that on the other side by greater than a certain amount.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that this is usually caused by fuel consumption in flight, not sloshing as you asked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, (as in your question) fuel can slosh between tanks in most aircraft through the vent line that often connects one tank to another such as in light Cessnas. However this is usually only a small quantity and furthermore the aircraft is usually in level flight so it's not really a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel sloshing inside of one tank could potentially imbalance the plane a bit but I've never ran into any real effects of this nor heard anyone mention it. Furthermore, most aircraft have some sort I baffles in the tanks (usually wig ribs) that prevent much sloshing, whether by design or not.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2016-02-18T15:35:13.213" LastActivityDate="2016-02-18T15:35:13.213" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25371" PostTypeId="2" ParentId="25316" CreationDate="2016-02-18T16:02:03.560" Score="0" Body="&lt;p&gt;Comm failure questions are always interesting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying at a significantly higher altitude because of a comm failure, and then having to get down, I would  chose an approach procedure that has a procedure turn or course reversal, and commence descent in a holding pattern over that procedure turn/reversal fix, at my ETA.&#xA;If there is no such approach, I would shuttle-descend over the chosen IAF on my inbound track to that IAF, making sure to go no lower than any minimum IFR altitude, and always remaining within the area of coverage of that minimum IFR altitude. I might tweak my inbound track a bit to avoid too sharp turns onto the intermediate or final approach course.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This could take quite some time if the flight plan was filed for FL410 and you suffer a total comm failure. While shuttling down from FL410, I might try to whip out a cellphone (and an ATC phone number).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Luckily comm failures, especially in the worst-case circumstances assumed here, don't happen too often.&lt;/p&gt;&#xA;" OwnerUserId="8681" LastActivityDate="2016-02-18T16:02:03.560" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25372" PostTypeId="1" AcceptedAnswerId="25376" CreationDate="2016-02-18T16:22:13.543" Score="3" ViewCount="230" Body="&lt;p&gt;I found an AFB in Germany that has some sort of hangars. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DUnhH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DUnhH.png&quot; alt=&quot;germanAfb&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And here there are more but in other AFB:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/IQDVW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IQDVW.png&quot; alt=&quot;germanafb2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they hangars? If so, why are they covered with grass?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-18T21:19:34.790" LastActivityDate="2016-02-18T21:19:34.790" Title="Are these hangars?" Tags="&lt;airport-design&gt;&lt;hangar&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25373" PostTypeId="1" AcceptedAnswerId="25374" CreationDate="2016-02-18T16:42:45.410" Score="1" ViewCount="2294" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;What is the purpose of runway grooving?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How does the airport drainage system work?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;Why do airports remove rubber from the runway?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="1696" LastEditDate="2018-04-09T15:03:48.160" LastActivityDate="2018-04-09T15:03:48.160" Title="What is the purpose of Runway Grooving?" Tags="&lt;airport&gt;&lt;runways&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25374" PostTypeId="2" ParentId="25373" CreationDate="2016-02-18T16:49:27.083" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the purpose of runway grooving?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The channels help to remove water from the runway. They also provide an area for the water to build up. With out these channels the water runs the risk of forming a thin surface covering the runway which can be very dangerous. As mentioned by john here in the comments this is usually known as hydroplaning and is the same as what happens to a car.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does the airport drainage system work?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is a bit of a guess but I assume they work like any other road drainage system and it will depend on where the airport is located. &lt;a href=&quot;http://dtic.mil/dtic/tr/fulltext/u2/a226418.pdf&quot; rel=&quot;nofollow&quot;&gt;Here is a very dated report prepared for the DOT on runway drainage&lt;/a&gt; that you may find of some interest. Here is &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5320_5d.pdf&quot; rel=&quot;nofollow&quot;&gt;the FAA's full paper on designing surface drainage for airports&lt;/a&gt;, it's a bit long but should cover what you are looking for.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why do airports remove rubber from the runway?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Tires obtain the best friction when they come in direct contact with the runway surface. Excess tire rubber that wears off and sticks to the runway can affect the tire/runway interactions. &lt;a href=&quot;https://en.wikipedia.org/wiki/Airfield_rubber_removal#Effects_of_rubber_buildup&quot; rel=&quot;nofollow&quot;&gt;This wiki article&lt;/a&gt; covers the main points pretty well.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5665" LastEditDate="2016-02-20T09:46:57.890" LastActivityDate="2016-02-20T09:46:57.890" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25375" PostTypeId="2" ParentId="25311" CreationDate="2016-02-18T16:53:20.507" Score="1" Body="&lt;p&gt;Sub charter is not used nowadays as a word expression. It's now called wet lease or ACMI. An ACMI specialist airline does not fly its own regular schedule, but usually flies for other airlines on shorter/longer notices (couple of flights or whole schedule). When WOW air started in Iceland, its schedule was flown by a Lithuanian ACMI operator. HiFly flies for Condor its service from Munich this winter, because Condor's 767s are undergoing heavy maintenance. Thomas Cook of UK is a permanent wet leaser to Condor (they are in the same holding). They provide aircraft and pilot crew, but Condor does fuel, maintenance and cabin crew. In the HiFly example above, HiFly provides full ACMI (aircraft crew maintenance insurance) for Condor.&lt;/p&gt;&#xA;" OwnerUserId="13582" LastEditorUserId="3159" LastEditDate="2016-02-18T17:46:43.597" LastActivityDate="2016-02-18T17:46:43.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25376" PostTypeId="2" ParentId="25372" CreationDate="2016-02-18T17:11:50.313" Score="8" Body="&lt;p&gt;They are hardened aircraft shelters (HAS) designed to protect aircraft from air attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Hardened_aircraft_shelter&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Hardened_aircraft_shelter&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first picture, they are also on a &quot;dispersal&quot; to spread them out and make them harder to target.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2016-02-18T17:11:50.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25377" PostTypeId="1" CreationDate="2016-02-18T18:15:05.523" Score="8" ViewCount="1956" Body="&lt;p&gt;I had a pilot tell me that a rude ATC controller was making him fly way off route and through clouds and turbulence. So he switched to VFR and climbed out of the mess and towards the direction he wanted to go. Without getting into who was right or wrong in this particular situation, how does one cancel IFR mid-flight?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-02-18T18:21:48.553" Title="How does a pilot switch from IFR to VFR mid-flight?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2021-05-03T01:18:32.490" ContentLicense="CC BY-SA 3.0" />
  <row Id="25378" PostTypeId="2" ParentId="25377" CreationDate="2016-02-18T18:21:48.553" Score="7" Body="&lt;p&gt;You simply tell ATC your request:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A: DEXPL, request cancel IFR.&lt;br&gt;&#xA;  R: DEXPL, roger, report VMC.&lt;br&gt;&#xA;  A: DEXPL, we are VMC.&lt;br&gt;&#xA;  R: DEXPL, IFR cancelled at 20. Squawk VFR, approved to leave frequency.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="572" LastActivityDate="2016-02-18T18:21:48.553" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25379" PostTypeId="1" AcceptedAnswerId="25383" CreationDate="2016-02-18T20:38:53.870" Score="1" ViewCount="4500" Body="&lt;p&gt;Do pilots (for example commercial pilots) need to use trigonometry (directly, with trigonometry knowledge) as part of their routine job?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, when is it most used and for what?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-24T15:51:45.500" LastActivityDate="2016-02-24T18:34:48.163" Title="Is trigonometry used by commercial pilots?" Tags="&lt;commercial-aviation&gt;&lt;aircraft-performance&gt;&lt;pilots&gt;&lt;performance-calculation&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25380" PostTypeId="2" ParentId="25379" CreationDate="2016-02-18T22:13:31.357" Score="1" Body="&lt;p&gt;I think the best example of routine use of trigonometry by pilots is to calculate winds aloft.  The data a pilot has on hand is his compass heading and his airspeed and his altitude and his true bearing based upon passing landmarks on the ground.  From this data he can calculate the wind direction and velocity he is witnessing at his location and altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally he would use a flight computer called an E6B which is a circular slide rule of sorts.  The E6B is easier to handle in turbulence than a pocket calculator.  I proved this to myself many years ago when I added a program to a programmable pocket calculator to do the computation.  It was hard to improve upon the time-tested &lt;a href=&quot;https://en.wikipedia.org/wiki/E6B&quot; rel=&quot;nofollow&quot;&gt;E6B&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-02-18T22:13:31.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25381" PostTypeId="2" ParentId="25367" CreationDate="2016-02-18T22:13:42.797" Score="4" Body="&lt;p&gt;Fly a &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Janus&quot; rel=&quot;nofollow noreferrer&quot;&gt;Schempp-Hirth Janus&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/Eiri-Avion_PIK-20&quot; rel=&quot;nofollow noreferrer&quot;&gt;PIK-20&lt;/a&gt; into rain. The effect will be dramatic. Make sure you have some place to land nearby! In both gliders your rate of sink will triple and the minimum speed will increase by maybe 20 km/h, so make sure you come in fast for landing while the wing is still wet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is the airfoil, the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=fx67k170-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wortmann FX 67-170&lt;/a&gt;. With 17% relative thickness and a very long laminar boundary layer, the recompression cannot be handled by a boundary layer which has been tripped near the leading edge. The consequence is flow separation already at moderate angles of attack if the wing is &lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956?s=3%7C0.0541#16956&quot;&gt;dirty from bugs&lt;/a&gt; or rain. The flight performance changes dramatically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then perform the same with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Schempp-Hirth_Discus&quot; rel=&quot;nofollow noreferrer&quot;&gt;Schempp-Hirth Discus&lt;/a&gt; or an &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASW_20&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASW-20&lt;/a&gt;. Sink speed will increase, but the effect is much less dramatic and the minimum speed will barely go up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no general rule of thumb, and two of the three reasons you suspect are indeed the major effects: Added mass from the water film over all upper surfaces and early tripping of the boundary layer. In big aircraft where the transition happens close to the leading edge anyway the difference made by rain is very small. It might even help by increasing engine thrust: Rain will cool the air and by absorbing heat when vaporizing will lower the temperature rise in the compressor of a jet engine. Note that many &lt;a href=&quot;http://forum.milavia.net/aviation-in-general/water-injected-take-offs-in-the-days-of-the-boeing-707/&quot; rel=&quot;nofollow noreferrer&quot;&gt;early jets used water injection&lt;/a&gt; to increase engine thrust on hot and high airfields.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For small aircraft with their lower volume to surface ratios the mass increase is more noticeable, and if the airfoil was optimized for minimum drag in clean conditions the early transition will effect a dramatic change in a few cases. The airfoils of most powered aircraft are not nearly as sensitive to rain. Normally, those aircraft are flown VFR, and the drop in visibility caused by rain will be the biggest effect.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-02-18T22:13:42.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25383" PostTypeId="2" ParentId="25379" CreationDate="2016-02-18T22:31:59.193" Score="8" Body="&lt;p&gt;&lt;em&gt;Note that this answer was given to the original question, &lt;code&gt;Do pilots need to use trigonometry as part of their routine job? If so, when is it most used and for what?&lt;/code&gt; The question was subsequently edited, after this answer was accepted. Much of the information provided in this answer does not now apply directly to the current question, but it does serve to provide context and for this reason it has been retained.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Pilots use trigonometry primarily for calculations involving wind angles, either for navigation or for cross-wind components for takeoff or landing. Note that pilots often accomplish these calculations with a flight computer such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/E6B&quot; rel=&quot;nofollow noreferrer&quot;&gt;E6B&lt;/a&gt;, a circular slide rule:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KbAVs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KbAVs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sub&gt;Image by Dave Faige — &lt;a href=&quot;https://en.wikipedia.org/wiki/File:StudentE6BFlightComputer.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt; — used under &lt;a href=&quot;https://creativecommons.org/licenses/by-sa/3.0/deed.en&quot; rel=&quot;nofollow noreferrer&quot;&gt;CC BY-SA 3.0&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many such flight computers are available, including electronic versions, such as the &lt;a href=&quot;http://www.sportys.com/pilotshop/sporty-s-new-electronic-e6b-flight-computer.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sporty's electronic E6B&lt;/a&gt;. Personally, I now prefer to use web-based software, but in flight school my preferred calculation method was a &lt;a href=&quot;https://en.wikipedia.org/wiki/TI-83_series&quot; rel=&quot;nofollow noreferrer&quot;&gt;TI-83&lt;/a&gt; programmed to do vector addition and other pre-flight calculations. In the cockpit, the &lt;a href=&quot;http://www.wwfc.ca/wp-content/uploads/2015/02/CR-3-Instructions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CR-3&lt;/a&gt;—a pocket version of the larger E6B mechanical flight computer and which can be operated with one hand—is usually the most functional method.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regardless of how they are performed, such calculations are typically for the purpose of either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Calculating wind correction angles for cross-country navigation based on forecast wind conditions, or&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Calculating crosswind component for takeoff or landing based on reported wind conditions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The later are fairly straight-forward; the former are more complex. Crosswind component is a simple tangent calculation. Wind correction angles are more complex involving vector addition taking into account magnetic course, true airspeed, forecast wind angle, and forecast wind speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, the original question was merely, do pilots need to &lt;em&gt;use&lt;/em&gt; trigonometry. The answer to that question is, &lt;em&gt;&quot;Yes&quot;&lt;/em&gt;. The question has since been edited to specify the use of trigonometry &quot;directly, with trigonometry knowledge&quot;. The answer to that question is, &lt;em&gt;&quot;No&quot;&lt;/em&gt;, pilots do not need to have a working understanding of trigonometry, though they do need to be capable of computing the above described wind problems. A pilot need not understand the trigonometry used by the calculator, slide rule, or FMS that he or she uses to perform these calculations. I know good pilots who have no real working knowledge of trigonometry and do quite well without it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a pilot flying in the IFR environment, wind correction calculation is less frequently a needed calculation since most navigational means provide for wind correction in some way. This is especially true of GPS or RNAV navigation, because the ground track can be compared to the aircraft's heading to show wind correction angle.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-24T18:34:48.163" LastActivityDate="2016-02-24T18:34:48.163" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25384" PostTypeId="1" AcceptedAnswerId="25622" CreationDate="2016-02-19T00:15:26.583" Score="3" ViewCount="1823" Body="&lt;p&gt;What is a fuel over pressure protector on the A320 and other aircraft? What is the purpose of this hole?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-02-26T05:55:13.153" Title="What is a Fuel Over Pressure Protector?" Tags="&lt;wing&gt;&lt;airbus-a320&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25385" PostTypeId="1" CreationDate="2016-02-19T02:35:03.810" Score="0" ViewCount="266" Body="&lt;p&gt;So a friend had an 'idea' where you could make an object land with 0 velocity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the idea is that you drop an object (like a rocket shape) from some altitude. To the object you attach fins (fixed propeller blades so to speak.) as it falls it starts rotating, due to the attached fins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now at some altitude above the ground you either:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) You rotate the fins to get reverse 'thrust' (you don't really have thrust, but you would slow down rotation.) &#xA;2) Retract the fins and expand new ones that face the opposite way (so they counter spin)&#xA;3) something along those lines (like extending flaps)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now one of the arguments he had as to why this works is because you could expand larger fins for the counter rotation, therefore getting more drag and generating more 'lift'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It feels like you cannot do this, but I cannot give a (good enough) reasonable explanation as to why it would or would not work (I'm a noob in this area.) So let's ask the people in the know... that's you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would love to see some 'proof' more so than speculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you in advance.&lt;/p&gt;&#xA;" OwnerUserId="13587" LastActivityDate="2016-02-19T12:11:50.160" Title="Dropping an object from really high, landing at 0 velocity due to 'free' reverse thrust" Tags="&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="6" ClosedDate="2016-02-19T18:33:45.407" ContentLicense="CC BY-SA 3.0" />
  <row Id="25387" PostTypeId="2" ParentId="25385" CreationDate="2016-02-19T03:50:31.540" Score="8" Body="&lt;p&gt;What you are describing is similar to a helicopter &lt;a href=&quot;https://en.wikipedia.org/wiki/Autorotation&quot;&gt;autorotation&lt;/a&gt;.  That is something that does work.  The rotors both generate drag and store rotational momentum.  Then, some of the momentum is converted to lift for landing.  &lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2016-02-19T03:50:31.540" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25388" PostTypeId="2" ParentId="21289" CreationDate="2016-02-19T03:55:33.957" Score="12" Body="&lt;p&gt;As a helicopter pilot with over 3,000 hours I can assure you that landing with a tail rotor malfunction is possible and that I have given over 100 check rides where I made students land with stuck pedals or simulated total loss of thrust.&#xA;As with many other questions it all depends on the type of helicopter.  If it has an adjustable fuel throttle, you can reduce the fuel flow while making a powered approach to a landing. In other helicopters with FADEC, you can make powered approaches using combinations of crosswinds and air over the tail to make a safe landing.  For a total loss of thrust you'll probably land in excess of wheel limitations, but even if pop all the tires you'll still walk away.&#xA;As far as flying 30 minutes to land-since we aren't in authoritative flight it's possible...but I wouldn't advise it because of the nature of Tail Gear Box issues.  If it's eating itself up, will it stay attached and in one piece?  How much will that shift weight and balance?  Will it catch fire?&lt;/p&gt;&#xA;" OwnerUserId="13588" LastActivityDate="2016-02-19T03:55:33.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25391" PostTypeId="2" ParentId="25385" CreationDate="2016-02-19T07:26:45.367" Score="1" Body="&lt;p&gt;Given the object has a terminal velocity, it should be possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before it hits the ground, it has a speed no greater than terminal speed.  Assuming it has some sufficient propeller system, it will require a finite amount of energy to slow the descent to zero at the altitude desired.  But since the start point is arbitrarily high, we can collect an arbitrarily large amount of energy from the fall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Imagine a quadcopter with depleted batteries and some sort of charging system that can be driven from the rotors.  Drop it from a height and let the descent charge up the battery.  Then a few feet before the ground, turn on the motors and let it hover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now this example uses batteries and electronics, but the argument doesn't change in character if you turn it into a kinetic spinning rotor instead (it's just harder to build).&lt;/p&gt;&#xA;" OwnerUserId="3159" LastEditorUserId="3159" LastEditDate="2016-02-19T07:37:17.280" LastActivityDate="2016-02-19T07:37:17.280" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25392" PostTypeId="2" ParentId="14102" CreationDate="2016-02-19T07:53:01.957" Score="9" Body="&lt;p&gt;It isn't German or even European, not with an OX-5 engine on the front - unfortunately there were hundreds of similar designs in the post-ww1 period, however the fact that it has a two bay wing and the struts are wire braced instead of having a diagonal narrows it down, and lo and behold, the Pitcairn PA-3 Orowing appears to be a match.&lt;/p&gt;&#xA;" OwnerUserId="13593" LastActivityDate="2016-02-19T07:53:01.957" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25393" PostTypeId="2" ParentId="25385" CreationDate="2016-02-19T12:11:50.160" Score="0" Body="&lt;p&gt;This reminds me of the defunct Roton experimental rocket, except that it had helicopter rotor blades powered by rockets at the tip to take off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It could be achieved with just one set of blades that have a very large pitch range adjustment. Pitch the blades downwards on descent so that they'll spin like a windmill and let the angular momentum build up, then pitch the blades upwards to convert the angular momentum into lift. The rotor system would require a flywheel of some sort to store the momentum needed to slow the craft down by a decent amount.&lt;/p&gt;&#xA;" OwnerUserId="13052" LastActivityDate="2016-02-19T12:11:50.160" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25394" PostTypeId="2" ParentId="10081" CreationDate="2016-02-19T12:22:58.917" Score="7" Body="&lt;p&gt;Yes they are. There are two pressures available to aircrew of fighters. One is a combat pressure for minimizing decompression if the cockpit is hit. The second is for ferry flights where a more comfortable pressure is maintained to reduce crew fatigue.&lt;/p&gt;&#xA;" OwnerUserId="13598" LastActivityDate="2016-02-19T12:22:58.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25396" PostTypeId="1" AcceptedAnswerId="25400" CreationDate="2016-02-19T15:24:21.980" Score="11" ViewCount="2708" Body="&lt;p&gt;I was just wondering: is it possible to have a commercial plane with no cockpit windshield, just external cameras and video screens?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question come in my mind after reading the nth occurrence of &lt;a href=&quot;http://avherald.com/h?article=493f2b06&amp;amp;opt=0&quot; rel=&quot;nofollow&quot;&gt;laser in pilot's eyes&lt;/a&gt;. Moreover, a structure without windscreen is surely lighter: when there are not passenger, we avoid to put windows! Which are the limits and the opportunities to this solution?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With &quot;ever&quot; I don't mean &quot;in centuries&quot; but in 30/40 years. &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="637" LastEditDate="2016-02-20T16:05:46.647" LastActivityDate="2016-05-25T20:19:48.857" Title="Is it possible for a plane to use cameras and screens instead of a clear windshield?" Tags="&lt;windscreen&gt;" AnswerCount="5" CommentCount="19" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25397" PostTypeId="2" ParentId="25396" CreationDate="2016-02-19T15:39:52.257" Score="15" Body="&lt;p&gt;It's entirely possible to do this now, it's simply not a good idea. The drawbacks to safety outweigh the benefits of doing so. If you have no cockpit windows an electrical or systems failure would leave pilots totally blind, without any references whatsoever. The &quot;mark I eyeball&quot; works in a wide variety of conditions and does not require electrical power of any kind. Plus, there's usually 4 of them in the cockpit, and chances are at least one of them will work. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-02-19T15:39:52.257" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25398" PostTypeId="1" AcceptedAnswerId="25399" CreationDate="2016-02-19T16:48:55.197" Score="2" ViewCount="2558" Body="&lt;p&gt;There's something below the door on almost every commercial aircraft. What is inside that box? The protrusion can be seen from the interior of the aircraft.&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Jump_seat&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/m3HDX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m3HDX.jpg&quot; alt=&quot;a320&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="15982" LastEditDate="2017-06-02T10:04:23.843" LastActivityDate="2017-06-02T10:04:23.843" Title="What is this protrusion on the door?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;&lt;emergency&gt;&lt;doors&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25399" PostTypeId="2" ParentId="25398" CreationDate="2016-02-19T16:55:45.947" Score="12" Body="&lt;p&gt;It contains the evacuation slide. From &lt;a href=&quot;http://www.airspacemag.com/flight-today/how-things-work-evacuation-slides-22196601/?no-ist&quot; rel=&quot;nofollow noreferrer&quot;&gt;airspacemag&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An escape slide sits inside a carbon fiber pressure cap covered by a casing of material similar to the aircraft interior walls—that big square box at the bottom of an airliner’s interior door.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here's an image from Boeing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9jE32.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9jE32.gif&quot; alt=&quot;Evacuation&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q4/2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Boeing, the positioning of evacuation slides inside the doors &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q4/2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;reduced the deployment time&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;By 1963, improvements in materials and inflation systems reduced the weight and bulk of the slide system, making it practical to move the slides out of the ceiling to the lower inboard face of the cabin doors (see fig. A). This location resulted in a still more efficient escape system, reducing the time needed to ready an escape slide from between 20 to 50 seconds to between 18 and 24 seconds, including door opening time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-19T16:55:45.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25400" PostTypeId="2" ParentId="25396" CreationDate="2016-02-19T17:13:20.473" Score="14" Body="&lt;p&gt;Is it possible? certainly yes. Airbus has &lt;a href=&quot;http://pdfaiw.uspto.gov/.aiw?docid=20140180508&amp;amp;SectionNum=1&amp;amp;IDKey=3BEBCC58961A&amp;amp;HomeUrl=http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2%2526Sect2=HITOFF%2526u=%25252Fnetahtml%25252FPTO%25252Fsearch-adv.html%2526r=1%2526p=1%2526f=G%2526l=50%2526d=PG01%2526S1=Zaneboni%2526OS=Zaneboni%2526RS=Zaneboni&quot; rel=&quot;nofollow&quot;&gt;applied for a patent for a windowless cockpit&lt;/a&gt; in which the external view is displayed in the cockpit using cameras and screens. The technology itself is available and some significant progress has been made in recent years in the related equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will it become a reality? Maybe. At present, there is nothing wrong with windshields in aircraft (pointing laser at aircraft is illegal; anyway, lasers can damage camera sensors too). Why fix something that ain't broken? In the future this may well be used, maybe in supersonic aircraft (For example, spike aerospace has proposed a design without cabin windows; interestingly, the design still has cockpit windows). Addition of cameras and displays adds one more layer of complexity, which is at present unnecessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, there are other issues to consider. In order to give the pilot with a view at least as good as the exiting aircraft, images from multiple cameras have to be 'stitched' and displayed. The system should be able to do this without any lag (F-35 had a similar problem while joining feeds from its DAS). Unless there is a compelling reason for the addition of cameras and displays, the windscreen is here to stay.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2016-05-25T20:19:48.857" LastActivityDate="2016-05-25T20:19:48.857" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25403" PostTypeId="2" ParentId="16995" CreationDate="2016-02-19T17:44:41.723" Score="0" Body="&lt;p&gt;As others have noted, it's because of the properties of aluminum. I'd like to add that there are good alternatives to using aluminum but the only one that's feasible on both performance and price is magnesium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Northrop's rocket powered XP-79 used a welded magnesium monocoque structure for example.&lt;/p&gt;&#xA;" OwnerUserId="13603" LastActivityDate="2016-02-19T17:44:41.723" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25405" PostTypeId="1" AcceptedAnswerId="25406" CreationDate="2016-02-19T18:12:30.980" Score="5" ViewCount="3624" Body="&lt;p&gt;Why does the cabin of commercial airplanes always smell like fuel smoke coming out from the internal ventilation a few minutes before taking off, I think when the pilot puts thrust into the engines before going to the runway?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few days ago I went on a trip and noticed this too, when landing. Is it normal?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason to have the passengers smoked?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!!&lt;/p&gt;&#xA;" OwnerUserId="13604" LastEditorDisplayName="user13363" LastEditDate="2016-02-20T19:46:24.573" LastActivityDate="2016-02-20T19:46:24.573" Title="Why do commercial airplanes smell like fuel smoke before take off?" Tags="&lt;airliner&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25406" PostTypeId="2" ParentId="25405" CreationDate="2016-02-19T18:56:35.583" Score="8" Body="&lt;p&gt;This is often a result of when the planes push back from the gate or if there is a direct tail wind on the ground. The pressurization system for aircraft uses bleed air from the compression stage of the engine. If the engines are running at push back or idling when a tail wind hits them the brief reversed airflow can cause some vaporous fuel to make its way forward in the engine and come through the air system causing the smell. &lt;a href=&quot;https://www.quora.com/Why-does-it-smell-like-fuel-when-waiting-for-takeoff&quot; rel=&quot;noreferrer&quot;&gt;This page covers it pretty well&lt;/a&gt;. Patrick Smith also &lt;a href=&quot;http://www.askthepilot.com/questionanswers/cabin-air-quality/&quot; rel=&quot;noreferrer&quot;&gt;touches upon it here&lt;/a&gt;.     &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="946" LastEditDate="2016-02-19T20:03:35.640" LastActivityDate="2016-02-19T20:03:35.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25408" PostTypeId="1" AcceptedAnswerId="25421" CreationDate="2016-02-19T20:26:37.833" Score="16" ViewCount="2914" Body="&lt;p&gt;I am interested in the process of using &lt;a href=&quot;https://en.wikipedia.org/wiki/Maritime_patrol_aircraft&quot; rel=&quot;noreferrer&quot;&gt;maritime patrol aircraft&lt;/a&gt; in an antisubmarine role. I hope there is some general answer, because I have no idea what such missions look like. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;How long can such a mission be and how big an area can it cover? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What techniques are used during such missions?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="3386" LastEditDate="2017-12-29T11:51:18.253" LastActivityDate="2019-11-06T19:06:41.367" Title="How do planes search for submarines?" Tags="&lt;military&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25409" PostTypeId="1" AcceptedAnswerId="25414" CreationDate="2016-02-19T20:53:42.453" Score="0" ViewCount="2430" Body="&lt;p&gt;What are the advantages and disadvantages of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_P-8_Poseidon&quot; rel=&quot;nofollow&quot;&gt;P-8 Poseidon&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Kawasaki_P-1&quot; rel=&quot;nofollow&quot;&gt;Kawasaki P1&lt;/a&gt; in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Maritime_patrol_aircraft&quot; rel=&quot;nofollow&quot;&gt;maritime patrol aircraft&lt;/a&gt; role? They were made for the same role, but they are different. The P-8 is something like converted from a civilian design while the P-1 is military-purpose built. What does that mean? What does the different number of engines mean for missions undertaken by these aircrafts? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;P-8 Posiedon (left) and Kawasaki P-1 (right)&#xA;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/P-8A_of_VP-5_and_Japanese_Kawasaki_P-1_at_NAF_Atsugi_in_2014.JPG/1024px-P-8A_of_VP-5_and_Japanese_Kawasaki_P-1_at_NAF_Atsugi_in_2014.JPG&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/0f/P-8A_of_VP-5_and_Japanese_Kawasaki_P-1_at_NAF_Atsugi_in_2014.JPG/1024px-P-8A_of_VP-5_and_Japanese_Kawasaki_P-1_at_NAF_Atsugi_in_2014.JPG&quot; alt=&quot;P-8 Posiedon and Kawasaki P-1&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Maritime_patrol_aircraft#/media/File:P-8A_of_VP-5_and_Japanese_Kawasaki_P-1_at_NAF_Atsugi_in_2014.JPG&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="13431" LastEditDate="2016-03-14T15:10:57.230" LastActivityDate="2016-03-14T15:10:57.230" Title="What are the major differences in operating the Boeing P-8 Poseidon and Kawasaki P1 in the maritime patrol aircraft role?" Tags="&lt;mpa&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ClosedDate="2016-03-06T16:41:51.100" ContentLicense="CC BY-SA 3.0" />
  <row Id="25410" PostTypeId="1" AcceptedAnswerId="25412" CreationDate="2016-02-19T21:53:03.637" Score="1" ViewCount="6405" Body="&lt;p&gt;I was asked about the difference today. The only difference I know is that mayday doesn't appear in the exams ( like the SOS parts of the book, you get the joke? :) ). I also found the &lt;a href=&quot;http://www.infoplease.com/askeds/mayday-sos.html&quot; rel=&quot;nofollow&quot;&gt;difference in the origin&lt;/a&gt;, but:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is used in aviation? Both are equivalent or there is actually a difference and the one should be preferred over the other?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8887" LastEditorUserId="167" LastEditDate="2016-02-20T05:30:44.197" LastActivityDate="2018-10-20T17:52:00.163" Title="Should &quot;mayday&quot; be preferred over &quot;SOS&quot; in an emergency?" Tags="&lt;emergency&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25411" PostTypeId="1" CreationDate="2016-02-19T22:18:11.077" Score="0" ViewCount="123" Body="&lt;p&gt;I will study for commercial pilot in May but I don´t know where I should study. I have 2 really good schools, one is in Canada (ICAO) the other one is in Florida (FAA), &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the advantages and/or differences of both licenses when it comes to a career in international aviation and what potential differences may it have in career and training paths.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we only talk about license not about schools.&lt;/p&gt;&#xA;" OwnerUserId="13607" LastEditorUserId="167" LastEditDate="2016-02-20T05:29:21.520" LastActivityDate="2016-02-20T05:29:21.520" Title="What are the benefits of an FAA over an ICAO license, and vice versa?" Tags="&lt;faa&gt;&lt;pilot-certification&gt;&lt;icao&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-02-20T08:43:39.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="25412" PostTypeId="2" ParentId="25410" CreationDate="2016-02-19T22:38:21.177" Score="11" Body="&lt;p&gt;SOS is a &lt;em&gt;distress&lt;/em&gt; signal. In the context of &lt;a href=&quot;https://aviation.stackexchange.com/questions/908/when-should-the-term-pan-pan-be-used-instead-of-mayday&quot;&gt;aviation emergency calls&lt;/a&gt; it would be equivalent to a &lt;code&gt;Mayday&lt;/code&gt; call, which is the standard voice signal for distress.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is, as far as I'm aware, no standard equivalent for an &quot;urgency&quot; (&lt;code&gt;pan-pan&lt;/code&gt;) situation in morse code. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As far as its use in aviation, most aviation communication today is by voice (radiotelephone), and &quot;SOS&quot; is not generally used in voice communication.&lt;br&gt;&#xA;Its used by morse code stations is because it is a short and easily recognized pattern:&lt;br&gt;&#xA;&lt;code&gt;. . .&lt;/code&gt; &lt;code&gt;- - -&lt;/code&gt; &lt;code&gt;. . .&lt;/code&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its recognizability is part of the reason it replaced the old Marconi CQD general distress call code&lt;br&gt;&#xA;&lt;code&gt;- . - .&lt;/code&gt; &lt;code&gt;- - . - .&lt;/code&gt; &lt;code&gt;- . .&lt;/code&gt;&lt;br&gt;&#xA;which was literally a general call to all stations (&lt;code&gt;CQ&lt;/code&gt;) signaling &quot;distress&quot; (&lt;code&gt;D&lt;/code&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find a reference, but I would assume there's at least one case in history where the SOS code was used by an aircraft (back when morse stations were common on aircraft).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An SOS signal could of course be transmitted today using the unmodulated carrier from your radio by simply keying the microphone, but that would only be useful if the voice circuit of your radio has failed and you had no other means to communicate. Otherwise voice contact or setting your transponder to &lt;a href=&quot;https://aviation.stackexchange.com/questions/15691/what-are-the-advantages-of-squawking-7700&quot;&gt;an appropriate code&lt;/a&gt; would generally be the preferred way to signal distress.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-02-19T22:38:21.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25413" PostTypeId="2" ParentId="25396" CreationDate="2016-02-19T22:41:54.693" Score="1" Body="&lt;p&gt;Somewhat, but the lack of depth perception may be an issue on the taxiways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But if lasers is the concern, I think they should install something similar to the auto darkening lenses used by welders to the front windows.&lt;/p&gt;&#xA;" OwnerUserId="13609" LastActivityDate="2016-02-19T22:41:54.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25414" PostTypeId="2" ParentId="25409" CreationDate="2016-02-20T00:49:48.003" Score="2" Body="&lt;p&gt;Both the aircraft were designed as replacements for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_P-3_Orion&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed P3C Orion&lt;/a&gt; when the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_P-7&quot; rel=&quot;nofollow noreferrer&quot;&gt;P7&lt;/a&gt; was cancelled. While the USN decided to convert a civilian aicraft (as is the norm for most MPA), the Japanese decided to design theirs from scratch (the aircraft was supposed to share a number of items with &lt;a href=&quot;https://en.wikipedia.org/wiki/Kawasaki_C-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kawasaki C2&lt;/a&gt;, which given the wildly different mission requirements, didn't go very well). Almost all the differences between the two aircraft, which share a number of similarities resulted from this differing approaches to design.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The P8 was derived from 737, a commercial airliner, which means that it is optimized for high speed, high altitude flight. Previosly, the MPA were optimised for low altitude operations. The P8, on the other hand has (relatively) highly swept wings with raked wingtips, optimized for high altitude cruise. This means the development of modified operational procedures for this aircraft. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MIK8x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MIK8x.jpg&quot; alt=&quot;P8&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.ainonline.com/sites/default/files/uploads/webp-8-flying.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;ainonline.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The P1, on te other hand, is purpose built to be a more or less a one-to-one replacement for the P3C, optimised for low altitude operation with strnthened structure. The wings are swept less and the wing area is relatively more compared to the P8. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7D3T1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7D3T1.jpg&quot; alt=&quot;P1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://battlemachines.files.wordpress.com/2015/11/111.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;battlemachines.files&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Operating the aircraft at high altitudes instead of lower ones also means that the operating principles are different. It is the main reason for the P8 not having the Magnetic Anamoly Detector (MAD), which was available in P3C (as well as P1, in the long boom in the tail). Last heard, UAVs are being developed with MADs to overcome this issue.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The P1 has larger windshields (which makes sense, as the crew would be able to scan better for ships at lower altitudes) and more hardpoints compared to the P8.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The P8 has only two engines compared to the four of P1, a significant difference. For aircraft operated in long stretches over areas without airfields, this could be a real issue. While so far no issues have been encountered in this regard, the loss of an engine in a P8 is basically a mission kill, which is not an issue with the P1.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The from-the-scratch development of the P1 alos has enabled the use of fly-by-light controls, which is a first for operational aircraft, allowing for lighter wiring and lesser interference.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One significant advantage of the P8 over P1 is that being based on one of the most successful and widely operated aircraft in history, spares and support will not be a big issue.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-20T00:49:48.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25415" PostTypeId="1" CreationDate="2016-02-20T02:54:16.020" Score="0" ViewCount="653" Body="&lt;p&gt;I was studying a dual-speed, high-bypass ratio turbofan engine dataset which I happened to obtain from NASA's website. This dataset was generated from C-MAPSS simulator where dataset has nominal and fault files. I studied the user guide doc and some other documents related to the same but I failed to understand the difference between these two files (ie. at the value/ parameter level).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have following questions, if anyone has used/aware of this dataset please help me:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;difference between nominal and fault file&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are 27 parameteres used, among these which parameters will affect fan, HPC, HPT, LPC, LPT&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;what is the threshold value for these parameters or when do we say that the parameter has reached its max value and above which it would lead to fault condition.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Here is the link where I got the dataset:&#xA;&lt;a href=&quot;https://c3.nasa.gov/dashlink/resources/140/&quot; rel=&quot;nofollow&quot;&gt;c3.nasa.gov/dashlink/resources/140/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13612" LastEditorUserId="167" LastEditDate="2016-02-20T05:32:14.270" LastActivityDate="2016-02-23T09:57:47.607" Title="How do I interpret these values in NASA's C-MAPSS dataset files?" Tags="&lt;aircraft-design&gt;&lt;nasa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25417" PostTypeId="1" CreationDate="2016-02-20T04:36:42.913" Score="7" ViewCount="801" Body="&lt;p&gt;Would you choose a route or altitude based on the information in a constant pressure chart? How does a constant pressure chart help a pilot plan his or her flight?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-10-03T16:51:37.077" Title="How does a constant pressure chart affect your preflight planning?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25418" PostTypeId="1" CreationDate="2016-02-20T04:42:47.540" Score="7" ViewCount="274" Body="&lt;p&gt;Immediately after an airport incident (e.g. a crash, runway overrun, fire etc.) it is fascinating to hear in recordings the ATC handle various duties so deftly . e.g. Ground vehicles, Fire, Go arounds, the actual aircraft involved, police, medics, tugs, closing runways or airports etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any training material on this? I want to read more (My day job is in Chemical Plants &amp;amp; I'm thinking there is stuff we could learn from Aviation Incident Response Procedures).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine these incidents are rare so any given controller doesn't get much by way of prior experience. So the best way to readiness would be via learning from past incidents or guidelines etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;NTSB reports &amp;amp; past ATC tapes do help a lot but has anyone compiled these learnings into advisory documents? Just like pilots use checklists for difficult situations are there any similar ATC checklists?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-07-11T08:33:43.760" LastActivityDate="2016-07-11T08:33:43.760" Title="Where can I find ATC Guidelines for handling Airport Incidents?" Tags="&lt;air-traffic-control&gt;&lt;incidents&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25419" PostTypeId="2" ParentId="25418" CreationDate="2016-02-20T06:31:47.457" Score="8" Body="&lt;p&gt;I'll answer from US ATC perspective having worked ATC at 3 different airports. First, I'll describe the alerts, then I'll describe training&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with all things, each airport has different procedures for how they handle emergencies or accidents. For each airport, the airport operator and the ATC Tower will come up with numerous Letter's of Agreement for how they want to handle things from lighting to emergency services. My first airport had 2 alert conditions, Orange and Red. Orange was go to standby positions, something is inbound requesting emergency services to be ready in case something happens. These are relatively common. Red was an actual accident/crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more common alerts are broken up into 3 categories I, II, and III. Alert I alerts are usually, a heads up to the crews to just be ready, but not go to the runway. Alert II are go to the standby positions, somebody's inbound with an issue and services are needing to go there. When this alert is declared, often as soon as the plane lands the runway is closed automatically until the airport inspects it(making sure no debris fell off the aircraft on landing). And Alert III is an actual crash. Most of the times, this is an immediate closure of the airport. This is due to the emergency services focusing on the accident and can't be available if something else were to happen on the field. Note, super large airports can have enough spare capacity to keep portions of the field still operating, depending on what all they have and how their command/control works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Training wise, it's often just on the job training and usually the light emergencies, where people just need to get back or gear stuck or similar non-crash emergencies. Usually in the course of a controller's training at their facility they'll get a couple of these and know how to react. There are discussions of past issues as well, when there's time and resources available to do these types of discussions. Full on crashes, as stated are rare, so likely the first time a controller has to deal with it, they'll have seen small issues in the past to help prepare them.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-02-20T06:31:47.457" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25420" PostTypeId="2" ParentId="14407" CreationDate="2016-02-20T07:32:25.793" Score="3" Body="&lt;p&gt;For the 430: use the outer knob to scroll to the AUX group. On page 4 (setup 2) there should be an item called SBAS SELECTION. If there is, it is WAAS equipped, however, verify WAAS is ON. &#xA;Similarly, if on the NAV group you scroll to the satellites page they will display as green rather than blue. But like before, verify WAAS is ON in the 'Setup 2' page of the AUX group.&lt;/p&gt;&#xA;" OwnerUserId="13614" LastActivityDate="2016-02-20T07:32:25.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25421" PostTypeId="2" ParentId="25408" CreationDate="2016-02-20T08:41:57.457" Score="24" Body="&lt;p&gt;&lt;strong&gt;Update.&lt;/strong&gt; Added: much more informative P-8 diagram, sonobuoy diagram, ASW training film (see bottom), ESM, minor formatting fixes. Removed: consolidated two sonobuoy loading pics (linked but not shown inline).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This principle method of airborne sub-hunting is using sonar to search a wide area around your ships in the direction of advance. The intent is less tracking subs as it is to deter them from getting into a good position to shoot and/or obtaining a firing solution on your ships.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ASW is a long, complex topic (see bottom for USN training film). This answer will be brief unless someone has more questions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airborne sensors include:&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;Sonobuoys&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Passive - (omnidirectional or directional) - subs are very quiet today. Detection ranges is extremely short. &amp;lt;100 m by some accounts. &lt;/li&gt;&#xA;&lt;li&gt;Active - all subs are coated with anechoic tiles to absorb acoustic energy&lt;/li&gt;&#xA;&lt;li&gt;A P-3 would go through about 10-30 buoys over a 6-10 hour mission&lt;/li&gt;&#xA;&lt;li&gt;A P-8 can apparently cary &lt;a href=&quot;http://www.b737.org.uk/mma.htm&quot; rel=&quot;noreferrer&quot;&gt;120&lt;/a&gt; sonobuoys.&lt;/li&gt;&#xA;&lt;li&gt;Some &lt;a href=&quot;http://www.sonobuoytechsystems.com/products/&quot; rel=&quot;noreferrer&quot;&gt;vendor specs&lt;/a&gt; are available.&lt;/li&gt;&#xA;&lt;li&gt;GREAT video of sonobuoy deployment. (This is one type. Not all are this complex.) &#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/eidMDdMK38s?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cWioG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cWioG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://thumbnails-visually.netdna-ssl.com/sonobuoy-hunting-for-flight-370_534748f85b113_w1500.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;. &lt;a href=&quot;https://www.flickr.com/photos/84131556@N06/13768398784&quot; rel=&quot;noreferrer&quot;&gt;Illustrator&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zJX9h.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zJX9h.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://i.stack.imgur.com/bgxz3.jpg&quot; rel=&quot;noreferrer&quot;&gt;Alternate view #1&lt;/a&gt;. &lt;a href=&quot;https://i.stack.imgur.com/U0Rx6.jpg&quot; rel=&quot;noreferrer&quot;&gt;Alternate view #2&lt;/a&gt;. &lt;a href=&quot;http://www.military.com/equipment/mh-60r-s-sea-hawk&quot; rel=&quot;noreferrer&quot;&gt;Credit&lt;/a&gt;. &lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;Dipping sonar&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Unique to ASW helos&#xA;&lt;a href=&quot;https://i.stack.imgur.com/A75Bm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/A75Bm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Credit: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:SH-60F_dipping_sonar.jpg&quot; rel=&quot;noreferrer&quot;&gt;USN&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;MAD&lt;/strong&gt; - magnetic anomaly detector&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The large boom extending behind the tail:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EJwLA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EJwLA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Credit: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Orion.usnavy.750pix.jpg&quot; rel=&quot;noreferrer&quot;&gt;DoD&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;looks for large metallic masses&lt;/li&gt;&#xA;&lt;li&gt;limitations: short range (100s of meters), which requires aircraft to fly very low over the surface (increasing airframe fatigue and fuel consumption). Descending from cruising altitude also takes time. &lt;/li&gt;&#xA;&lt;li&gt;upside: good localization (spatial accuracy), relatively few false positives. &lt;/li&gt;&#xA;&lt;li&gt;downsides: Equipment is large and heavy. For these reasons, a MAD boom is not included on the current USN P-8, the navy's newest long range maritime patrol aircraft. &lt;/li&gt;&#xA;&lt;li&gt;Counter-measures: &#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sub can dive deeper to reduce their chances of being detected. Typical SSN operating depths are 400 m. The Type 214 claims a 700 m test depth. &lt;/li&gt;&#xA;&lt;li&gt;Some modern subs are made from non-magnetic steels (eg, German Type 212, Type 214) or titanium (Soviet Sierra, Alfa, and Papa class SSNs, portions of the &lt;a href=&quot;https://ru.wikipedia.org/wiki/%D0%9F%D0%BE%D0%B4%D0%B2%D0%BE%D0%B4%D0%BD%D1%8B%D0%B5_%D0%BB%D0%BE%D0%B4%D0%BA%D0%B8_%D0%BF%D1%80%D0%BE%D0%B5%D0%BA%D1%82%D0%B0_941_%C2%AB%D0%90%D0%BA%D1%83%D0%BB%D0%B0%C2%BB#/media/File:Typhoon_class_Schema.svg&quot; rel=&quot;noreferrer&quot;&gt;Typhoon's 5 pressure hulls&lt;/a&gt;). &lt;/li&gt;&#xA;&lt;li&gt;Subs also undergo degaussing&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Y07Wg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y07Wg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;LA-class USS Toledo (SSN-769) prepares to get underway after four days at the Magnetic Silencing Facility. 5 Feb 2010. Credit: &lt;a href=&quot;http://www.ctf74.navy.mil/imagery/2010/02/100205-N-4397B-002.jpg&quot; rel=&quot;noreferrer&quot;&gt;USN&lt;/a&gt;&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;&lt;strong&gt;Radar&lt;/strong&gt;&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Historically, more useful for detecting subs on the surface, forcing them to spend more time underwater, where they were less effective (slower, limited endurance, limited sensor range). For much of WWII, German U-boats were essentially submersible torpedo boats. Most of their attacks were actually made on the surface. &lt;/li&gt;&#xA;&lt;li&gt;Today, our improved radars can detect submarine periscopes (and their wakes) at significant distances, forcing subs to take only very short glimpses. The periscope is actually quite useful for ID-ing targets and obtaining ranges and headings much more quickly than stalking with sonar alone. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Signal intercept, ESM&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You may detect a sub communicating over radio. You may also detect a sub if it uses its radar (very seldomly).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Visual&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If you're directly above a sub at shallow depth, you can see it. Needless to say, this is &lt;em&gt;extremely&lt;/em&gt; rare, but is one reason operating in shallow, littoral waters is dangerous. If you're lucky, you might spot a periscope wake. It's also unlikely you'll see a surface wake. At periscope depth, subs move very slowly. And at operating depths, surface wakes are extremely minute, likely undetectable even by radar and advanced processing, although attempts have been made.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1HH5b.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1HH5b.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:HMAS_Rankin_at_periscope_depth.jpg&quot; rel=&quot;noreferrer&quot;&gt;Credit&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;EO/IR&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;General SA but may occasionally detect exhaust fumes (eg SSK snorkeling) or periscopes/wakes. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Other non-acoustic methods&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Chemical (eg hydrocarbon sensor) - to detect snorkeling subs recharging their batteries&lt;/li&gt;&#xA;&lt;li&gt;LIDAR - potentially faster than MAD. Limited depth and search band. Less effective in turbid coastal waters. Not used operationally. &lt;/li&gt;&#xA;&lt;li&gt;Radar to detect the minute thermals from warm water heated by reactors. (Claimed by Russians, not demonstrated by US.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Examples&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Land-based maritime patrol aircraft examples: P-3 Orion (modded L-188 Electra), P-8 Poseidon, , &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;P-8 Poseidon&lt;/strong&gt; (modded 737-800ERX).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DZYJG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DZYJG.jpg&quot; alt=&quot;p-8a from b737 tech site&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;The Boeing 737 Technical Site. &lt;a href=&quot;http://www.b737.org.uk/mma.htm&quot; rel=&quot;noreferrer&quot;&gt;Source page with lots more info&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;BAE Nimrod&lt;/strong&gt; (based on the de Havilland Comet)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gVBTO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gVBTO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Nimrod_MRA4_1.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carrier based platforms include: S-3 Viking, SH-60 Seahawk&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SH-60 Seahawk&lt;/strong&gt; - sensors includes a variable-depth active/passive sonar, sonobuoys, and MAD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HZJGf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HZJGf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;MAD bird (orange/red). Credit: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:SH-60B_Seahawk2.jpg&quot; rel=&quot;noreferrer&quot;&gt;DoD&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Anti-submarine warfare intro&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=4OgISrfPDfE&quot; rel=&quot;noreferrer&quot;&gt;COORDINATED ASW PART 1 - Coordinated Anti-Submarine Warfare 2089&lt;/a&gt; (HD version below)&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/PZ5I6eb9rt4?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2017-12-29T04:28:36.187" LastActivityDate="2017-12-29T04:28:36.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25424" PostTypeId="1" AcceptedAnswerId="25429" CreationDate="2016-02-20T10:26:49.643" Score="10" ViewCount="1898" Body="&lt;p&gt;I have been trying to understand how a PESA radar works. Essentially, it uses one signal that is electronically delayed. How is the reception coordinated and known by the receiver?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am interested in understanding the logic behind in delay of signal and reception/identification.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="5517" LastEditDate="2016-02-22T18:08:29.057" LastActivityDate="2016-12-19T01:22:48.497" Title="How does a PESA radar work?" Tags="&lt;radar&gt;&lt;pesa-radar&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25425" PostTypeId="5" CreationDate="2016-02-20T10:28:11.713" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-20T10:28:11.713" LastActivityDate="2016-02-20T10:28:11.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25426" PostTypeId="4" CreationDate="2016-02-20T10:28:11.713" Score="0" Body="Passive Electronically Scanned Array radar that uses a single frequency sending it to phase shift modules sending it to individual emiting elements" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2016-02-20T14:11:54.407" LastActivityDate="2016-02-20T14:11:54.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25427" PostTypeId="2" ParentId="25396" CreationDate="2016-02-20T12:20:50.673" Score="2" Body="&lt;p&gt;That should be ... exciting ... during an electrical failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck getting it approved for use anywhere in the world, you can't even build a pure glass cockpit in many jurisdictions. Likewise you can have all the cameras you like provided you can still look out the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's certainly technically feasible but it's not a good idea.&lt;/p&gt;&#xA;" OwnerUserId="3439" LastActivityDate="2016-02-20T12:20:50.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25428" PostTypeId="2" ParentId="25367" CreationDate="2016-02-20T12:32:20.830" Score="5" Body="&lt;p&gt;While Peter Kämpf already commented the effects I'll take a look at the numbers. Don't expect this calculations to be exact predictions, rather worst cases to know the magnitude of following effects:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Mass increase due to rain drops&lt;/li&gt;&#xA;&lt;li&gt;Forces due to drops hitting the wing&lt;/li&gt;&#xA;&lt;li&gt;Early tripping of the boundary layer&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;After deducing some equations I'll feed them with the data of two different airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Mass increase due to rain drops&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dew layer you find on your airplane in the morning can reach a &lt;a href=&quot;https://en.wikipedia.org/wiki/Dew#Significance&quot; rel=&quot;noreferrer&quot;&gt;maximum altitude&lt;/a&gt; of 0.8 mm. Raindrops, which do not fill the complete wing surface, don't usually exceed 2 mm diameter.Therefore taking an average distributed height of $h_W=1mm$ for the water on the wing should be still a worst-case prediction.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$m_{Drops}=\rho_{W} \cdot A\cdot h_W$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$A$ is the projected area of the aircraft on the horizontal plane and $\rho_W$ water density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Forces due to drops hitting the wing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal &lt;a href=&quot;https://en.wikipedia.org/wiki/Rain#Intensity&quot; rel=&quot;noreferrer&quot;&gt;rainfall intensities&lt;/a&gt; are about 5 mm/hour and we already speak about violent rain with precipitation rates beyond 50 mm/hour. But let us take the &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_weather_records#Rain&quot; rel=&quot;noreferrer&quot;&gt;heaviest rate&lt;/a&gt; ever measured: $I_R=38mm/min$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drops fall normally with $v_{Drop}=10m/s$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To simplify the calculation I'll assume vertical rain and that once a drop hits the airplane it sticks to it. In reality you don't accelerate every drop to the airplane speed nor slow its vertical speed down to 0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;i) Drag increase&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ \Delta D= \rho_{W} \cdot I_R \cdot A \cdot v_{airplane}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ii) Lift decrease&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ \Delta L= \rho_{W} \cdot I_R \cdot A \cdot v_{Drop}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To calculate the total drag ($D=C_D\cdot \frac{\rho_{Air}}{2} V^2 \cdot A$) I've used $C_D=0.035$. $V$ is the cruise speed of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Early tripping of the boundary layer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While it's possible to find airfoil polars in rain searching the Internet, I'll first look at a &quot;bugs influence&quot; diagram where you can see the effect of small disturbances at the nose without other effects overlayed. Bugs and raindrops are similar in size, therefore the comparison should be valid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OswGZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OswGZ.png&quot; alt=&quot;Drag coefficient with and without bugs&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.iag.uni-stuttgart.de/lehre/lehrveranstaltungen/lehrveranst_master/einz_vorl_master/vorlesungen_flugzeuaerodynamik/profilentwurf.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The polar above shows how the drag can double (100% increase)just because of some small disturbances at the leading edge. Keep in mind that in modern profiles the effect will probably be smaller. The next polar is from a transport aircraft airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4192N.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4192N.png&quot; alt=&quot;Transportation Research Record 1428&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://onlinepubs.trb.org/Onlinepubs/trr/1994/1428/1428-004.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not so important as in the glider airfoil, the drag coefficient increase (experimental results) is everywhere at least a two-digit percentage.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airplanes&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've taken two airplanes with really different wing loadings: A1 would be something between the two Solar Impulse models and A2 a single engine four-seater like a Cessna 172. The last three rows give the drag, lift and mass difference as described above as a percentage of its total value.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;|                       |            A1 |     A2 |&#xA;|-----------------------+---------------+--------|&#xA;| Mass m [kg]           |          1600 |   1000 |&#xA;| Area A [m^2]          |           210 |     20 |&#xA;| Wing loading [kg/m^2] |           7.6 |     50 |&#xA;| Cruise speed V [m/s]  |            20 |     58 |&#xA;| Lift L [N]            |         15696 |   9810 |&#xA;| Drag D [N]            |          1800 |   1323 |&#xA;| Drops mass mW [kg]    |           210 |     20 |&#xA;| Drag increase dD [N]  |          2660 |    703 |&#xA;| Lift decrease dL [N]  |          1330 |    127 |&#xA;|-----------------------+---------------+--------|&#xA;| dD/D [%]              |           147 |     53 |&#xA;| dL/L [%]              |           8.5 |    1.3 |&#xA;| mW/m [%]              |            13 |      2 |&#xA;|-----------------------+---------------+--------|&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SUMMARY&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a normal GA airplane the water mass on the wings and the lift decrease influence due to raindrops hitting the wing even considering the worst possible conditions are low single digit percentages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While drag increase due to drops hitting the wing is relevant in the extreme case I took here, under normal conditions it should be below single digit percentages too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand the drag increase due to the early tripping of the boundary layer is at least a two digit percentage, at high lift coefficients even more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes with lower wing loading are more affected with rain precipitation.&lt;/p&gt;&#xA;" OwnerUserId="8749" LastActivityDate="2016-02-20T12:32:20.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25429" PostTypeId="2" ParentId="25424" CreationDate="2016-02-20T13:05:32.933" Score="20" Body="&lt;p&gt;Your question: What is the logic behind the delay of the signal and how is the echo signal later bound with the signal sent?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A PESA is an array of individual antennas. Each antenna radiates the same signal, except the phase. The phase adjustment for each antenna allows for the non-moving array to behave like if it could be rotated, i.e. the direction the energy is sent to or receive from can be selected by adjusting the phase for the individual antennas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Varying the signal phase for an individual antenna of the array can be done by delaying the signal for this antenna, which in turn is as easy as&#xA;making the electrical conductor (or waves guide) between the oscillator and the antenna longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PESA &lt;a href=&quot;https://en.wikipedia.org/wiki/Radar#Transit_time&quot; rel=&quot;noreferrer&quot;&gt;determines the transit time&lt;/a&gt; exactly like another more traditional one with a single rotating antenna. A signal sent by a PESA, after it has been sent, is indistinguishable from a signal sent by a rotating antenna radar.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The principle of a primary radar is to send a radio signal in a given direction and wait for a possible echo. The direction of the radiation pattern is used in determining the direction (azimuth and elevation) of the reflecting object. The antenna must be very directional (small solid angle of the radiation pattern), else the angle determination cannot be precise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/l7mX0.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l7mX0.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Radiation pattern of an antenna with a parabolic reflector (&lt;a href=&quot;http://watkin-online.com/openpage.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That means the antenna must be rotated to scan a useful portion of the sky (or ground).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To clarify the wording used, an antenna is usually composed of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A &lt;em&gt;radiator&lt;/em&gt; which receives the signal to be transmitted (it also collects the waves in reception). The radiator is the interface between electrons and waves and vice-versa.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;em&gt;reflector&lt;/em&gt; used to reflect the waves from the radiator (it also focuses the waves on the radiator in reception).&lt;/li&gt;&#xA;&lt;li&gt;Sometimes &lt;em&gt;directors&lt;/em&gt; to narrow the radiation pattern of the system.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The radiation pattern of an antenna is mostly determined by the shape of the reflector (e.g. the &lt;a href=&quot;http://www.wikiwand.com/en/Parabolic_antenna&quot; rel=&quot;noreferrer&quot;&gt;parabolic reflector&lt;/a&gt;) which only illuminates a given fraction of the space and, due to interferences, also varies the energy based on the direction the energy is sent to or received from. Due to the reflector, a signal from the radiator will usually travels using different paths created by the multiple reflections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interferences are the result of combining the electromagnetic signals at a given point. For signals having the same frequency, the phase determines if signals are added (same phase) or canceled (opposite phases).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E7OvF.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E7OvF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Phase determines how signals interfere (&lt;a href=&quot;https://micro.magnet.fsu.edu/primer/java/interference/waveinteractions/index.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can apply this phenomenon to the multiple signals created in an antenna composed of a radiator and a cylindrical reflector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZxhNn.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZxhNn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Signals summation on a cylindrical reflector antenna creates a privileged direction of radiation with some secondary (unwanted) lobes (&lt;a href=&quot;https://nzwifi2.thruhere.net.nz/Information/Antenna/Parabolic%20Templat.htm&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Array of radiators (electronically scanned array, ESA)&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way of varying the privileged direction of a radiation pattern is to create interferences on a voluntary basis, so that they create a stronger signal in the desired direction, and a weaker signal elsewhere. The advantage is that this electronic direction change can be much quicker than a mechanical rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to create interferences is to send the radar signal from an array of small radiators instead of a single big one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nU98l.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nU98l.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Close-up of the front of the old Cobra Judy radar (&lt;a href=&quot;https://en.wikipedia.org/wiki/AN/SPQ-11&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type of array is quite familiar under the name interferometer in the field of astrophysics:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fMFc4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fMFc4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Siberian Solar Radio Telescope (SSRT) interferometer observing the Sun at 5.7 GHz (&lt;a href=&quot;http://herrero-radio-astronomy.blogspot.fr/2014/02/kochanov-and-4-collaborators-2013.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If all radiators are fed with the same signal, then interferences will occur the same way on the whole surface and the result will be that the direction perpendicular to the array is privileged (image on the left side).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xh9Xk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xh9Xk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Electronic beam-deflection (left: bore sight, right: deflected (&lt;a href=&quot;http://www.radartutorial.eu/06.antennas/Phased%20Array%20Antenna.en.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The right side of the image shows what happens if the signal sent to the individual radiators is delayed in a coordinated way: Delay increases from right to left on the array. It must be remembered that delay means phase here. The direction of the signal is now oblique due to the the location of constructive and destructive interferences. The red circles indicates signal with the same phase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this &lt;a href=&quot;http://www.radartutorial.eu/06.antennas/pic/if3.big.gif&quot; rel=&quot;noreferrer&quot;&gt;animation&lt;/a&gt; too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Delaying an electric signal is quite easy: Just increase the length of the conductor (see &lt;a href=&quot;https://en.wikipedia.org/wiki/Analog_delay_line&quot; rel=&quot;noreferrer&quot;&gt;analog delay line&lt;/a&gt;). A length variation between 0 and the wave length (e.g. 10 cm for a wavelength of 10 cm -- 3 GHz) allows to sweep the whole range of possible phase values from 0 to 360°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Indeed there are other ways to delay a signal without adjusting the length, but they are electrically equivalent. When signals are digitized, it's really easy to process them, there is less electro-mechanical constraints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By varying the phase on individual radiators we can steer the signal as if the antenna had been rotated, but we can also focus the energy on a target.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dxwGU.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dxwGU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.ob-ultrasound.net/somers.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;PESA vs AESA&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two approaches for feeding individual radiators with phase-shifted signals: active and passive:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Active means the radiator has its own oscillator to create its own signal. The active element must receive the value of the phase shift to use from a central element which coordinates the whole array.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Passive means the radiator receives the signal to be sent and just radiates it. The signal must already have the required phase. This is usually done with a single oscillator which feeds an array of phase shifters which in turn feed the array of radiators.&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/fIs1n.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fIs1n.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://smg.photobucket.com/user/xu-an/media/phased_array_illus.jpg.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Transmission vs reception&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The beam formed by the array concentrate the energy during transmission. The signal sent is not different than one sent with a single large radiator (rotating radar antenna). This is also a general result of adding and canceling energy by interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An array conforms to the general rule: An antenna is reversible, the characteristics of the radiation pattern are also valid in reception. That means:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Receive the same signal on all radiators&lt;/li&gt;&#xA;&lt;li&gt;Add individual delays (phase shifts) to obtain a privileged direction of energy origin. The phase values are inverted compared to the ones used for sending in this direction.&lt;/li&gt;&#xA;&lt;li&gt;Mix all signals into a single one to have them interfer and obtain a single mixed signal, equivalent to the one that would have been received with a rotating antenna.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The effect is that energy originating from directions other than the privileged one will be weakened, and the energy in the privileged direction will be emphasized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the phase is used to change the radiation pattern (process known as &lt;em&gt;beam forming&lt;/em&gt;), but the rest of the radar is unchanged compared to a rotating single antenna one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Tell me if there is something that is not clear, I'll improve the post as necessary.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Phase shifter&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned a phase shifter is used on each individual antenna of the array. It should prevent signal loss, distortion and noise addition, and the phase must be controlled accurately and quickly, by steps or continuously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For step by step (&lt;em&gt;digital&lt;/em&gt;), delay lines are used, with a possibility to connect a variable number of them using switching diodes (e.g. pin diodes). See more on &lt;a href=&quot;http://www.radartutorial.eu/06.antennas/Phase%20Shifter.en.html&quot; rel=&quot;noreferrer&quot;&gt;RadarTutorial.eu&lt;/a&gt; with an example of 4-bit shifter (16 phase-shift values). More details on this datasheet for a &lt;a href=&quot;http://module-csums.cognix-systems.com/telechargement/13-8-1.pdf&quot; rel=&quot;noreferrer&quot;&gt;6-bit shifter on S-band&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Continuous (&lt;em&gt;analog&lt;/em&gt;) control can rely on a resonant circuit (LC) to delay the signal. The capacity value can be mechanically changed in MEMS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/enuc9.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/enuc9.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(source)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This extends past what I know in the domain, but other technologies exist, and are detailed in &lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080001449.pdf&quot; rel=&quot;noreferrer&quot;&gt;Array Phase Shifters: Theory and Technology&lt;/a&gt; (Nasa, 2007), including:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Another style of phase shifter uses coupled microstriplines as dc&#xA;  electrodes to polarize a thin [...] ferro-electric film [...]. These&#xA;  planar phase shifters are fairly compact, low loss, easy to fabricate,&#xA;  and can provide 360° of phase shift with bias voltages under 350 V.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Phase shifters design depends on the operating wavelength of the radar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Radiators used in a phased array antenna&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again the operating frequency impacts the radiators design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low frequencies may use:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://tatoott1009.files.wordpress.com/2012/02/array1.jpg?w=470&quot; rel=&quot;noreferrer&quot;&gt;A pair of crossed dipoles&lt;/a&gt; to allow polarization changes during the pulse travel and the reflection on the target.&lt;/li&gt;&#xA;&lt;li&gt;A &lt;a href=&quot;http://www.vikascommunications.com/images/206.5%20antenna_array_Wind_Product.jpg&quot; rel=&quot;noreferrer&quot;&gt;Yagi&lt;/a&gt; antenna.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Higher frequencies use other designs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.antenna-theory.com/antennas/aperture/slot.php&quot; rel=&quot;noreferrer&quot;&gt;Notch&lt;/a&gt; antenna (slot). Used on Russian &lt;a href=&quot;http://defence.pk/threads/mini-awacs-the-powerful-n011m-bars-hybrid-radar-system-su-30-mki.256937/&quot; rel=&quot;noreferrer&quot;&gt;N011M&lt;/a&gt; (also note the dipole array for lower frequency scan of this hybrid radar).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Patch_antenna&quot; rel=&quot;noreferrer&quot;&gt;Patch&lt;/a&gt; antenna (microstrip).&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Vivaldi_antenna&quot; rel=&quot;noreferrer&quot;&gt;Vivaldi&lt;/a&gt; antenna (tapered slot) for broadband spectrum.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;More on &lt;a href=&quot;http://www.radartutorial.eu/06.antennas/Phased%20Array%20Antenna.en.html&quot; rel=&quot;noreferrer&quot;&gt;RadarTutorial.eu&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-12-19T01:22:48.497" LastActivityDate="2016-12-19T01:22:48.497" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25430" PostTypeId="1" AcceptedAnswerId="25445" CreationDate="2016-02-20T14:13:18.650" Score="3" ViewCount="411" Body="&lt;p&gt;Pilots should strive to fly precisely, but we sometimes reach task saturation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When ATC gives a heading, receives the correct readback, but observes a 10- to 15-degree difference between the actual and intended tracks, does the specialist incorporate this difference into future vectors? Do approach and traffic separation vectors generally have a healthy margins of error?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does apparent compass deviation or directional gyro precession factor into vectors that ATC issues?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-02-20T15:37:07.287" LastActivityDate="2016-02-20T23:48:59.837" Title="How does ATC deal with apparent compass errors when giving vectors?" Tags="&lt;air-traffic-control&gt;&lt;heading&gt;&lt;magnetic-compass&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25433" PostTypeId="2" ParentId="25417" CreationDate="2016-02-20T18:01:07.040" Score="0" Body="&lt;p&gt;A constant pressure chart by itself doesn't provide any useful data for flight planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it shows a height of a given pressure level, you can make some assumptions about air mass temperature and pressure systems. You could also determine wind velocity and direction to some accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However most of the information available is usually shown in a pre-computed and pilot-friendly way in other charts, such as sw-charts and wind/pressure charts.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-02-20T18:01:07.040" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25434" PostTypeId="1" AcceptedAnswerId="84256" CreationDate="2016-02-20T18:31:30.537" Score="6" ViewCount="1710" Body="&lt;p&gt;In typical usage, the terms seem to be used interchangeably. However, aircraft must be transponder- or encoder-equipped for traffic advisories to be possible, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What information does each provide to pilots that the other does not?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2021-02-12T04:52:22.250" Title="What are the differences between radar flight following and traffic advisories?" Tags="&lt;air-traffic-control&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25435" PostTypeId="2" ParentId="25368" CreationDate="2016-02-20T19:04:34.000" Score="22" Body="&lt;h3&gt;Pitot tubes&lt;/h3&gt;&#xA;&lt;p&gt;F-117 pitot tubes&#xA;&lt;a href=&quot;https://i.stack.imgur.com/oUUyj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oUUyj.jpg&quot; alt=&quot;f117 pitot tubes&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://youtu.be/U30_-crRpUg?t=45&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;. Also a look at the FLIR and DLIR.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;F-22 pitot tubes&#xA;&lt;a href=&quot;https://i.stack.imgur.com/AWfYI.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AWfYI.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://www.airsceneuk.org.uk/hangar/2005/c130/022-02-0039-F-22A.jpg&quot; rel=&quot;noreferrer&quot;&gt;AIR-SCENE UK&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Incorporation of those pitot probes were a cost savings measure. They are also a dominant RCS signature source in the forward and side sectors. The original ATF proposal was for a flush air data system that would have cost many $ millions. - &lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?p=55452#p55452&quot; rel=&quot;noreferrer&quot;&gt;djcross&lt;/a&gt;, F-16.net&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;F-35 pitot tubes&#xA;&lt;a href=&quot;https://i.stack.imgur.com/krYUW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/krYUW.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://breakingdefense.com/wp-content/uploads/sites/3/2014/11/F-35-first-catapult-launches-USS-Nimitz2.jpg&quot; rel=&quot;noreferrer&quot;&gt;Breaking Defense&lt;/a&gt;. &lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?f=60&amp;amp;t=25796&quot; rel=&quot;noreferrer&quot;&gt;More pics&lt;/a&gt; on F-16.net.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;h3&gt;Canopies&lt;/h3&gt;&#xA;&lt;p&gt;The canopy keeps radar energy out of the cockpit, the inside of which is filled with messy odds and ends. The F-22 and F-35 canopies are gold-impregnated for this reason. &lt;em&gt;Note: the F-22's canopy is &lt;a href=&quot;https://books.google.com/books?id=k8skNF7RZVkC&amp;amp;pg=PA48&amp;amp;lpg=PA48&amp;amp;dq=indium%20tin%20oxide%20f-22&amp;amp;source=bl&amp;amp;ots=9daL7xIEac&amp;amp;sig=Z_S-jSlMtJCgPdX6tO0czc25m0c&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwj-sJbqxpjNAhUJlR4KHajCDXQQ6AEILDAC#v=onepage&amp;amp;q=indium%20tin%20oxide%20f-22&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;possibly&lt;/a&gt; doped with &lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?p=315649&amp;amp;sid=50ad38a90d0fb79dd3c6456ad6f4b8e4#p315649&quot; rel=&quot;noreferrer&quot;&gt;indium-tin-oxide&lt;/a&gt;, not gold.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;In the EA-6B's case, the gold keeps the a/c's own radar energy out of the cockpit---those ram-air turbines are powering two jamming pods. The coating (and a similar one applied to visors) also turn black to protect the pilot's vision from nuclear detonations.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zoira.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zoira.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:EA-6B_Prowler_takes_off_from_Eielson_AFB.jpg&quot; rel=&quot;noreferrer&quot;&gt;USAF&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PPkAY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PPkAY.jpg&quot; alt=&quot;f22 gold&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File:Lockheed_Martin_F-22A_Raptor_JSOH.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FV2p8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FV2p8.jpg&quot; alt=&quot;f35 gold&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: Lockheed Martin. &lt;a href=&quot;https://www.flickr.com/photos/lockheedmartin/sets/72157601438420763/&quot; rel=&quot;noreferrer&quot;&gt;Flickr set&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Notice the similarly tinted/treated window beneath the F-35's nose. That's the aperture for the EOTS (electro-optical targeting system), an IRST and ground targeting system. Also note the two small pitot tubes above the EOTS. I remember pitot plates were being developed for the F-35 (which are stealthier but more difficult to develop), but I haven't heard anything about it in a while.&lt;/p&gt;&#xA;&lt;h3&gt;Sensor apertures&lt;/h3&gt;&#xA;&lt;p&gt;The coverings are transparent to the operating bands of the radar/radio/etc underneath.&lt;/p&gt;&#xA;&lt;p&gt;The F-22 and F-35 have fixed AESA radars. The latter is angled up to minimize returns.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hOSYU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hOSYU.jpg&quot; alt=&quot;apg81&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Credit: Northrop Grumman. &lt;a href=&quot;http://www.northropgrumman.com/MediaResources/Pages/Photo.aspx?pid%3DAN-10137_001%26rel%3D%2F%26name%3DPhotos&quot; rel=&quot;noreferrer&quot;&gt;Hi res&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Some radar energy enters through the aperture. Whatever isn't reflected is absorbed by the radar itself or heaps of RAM, which hides the messy rear/sides.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8w8bo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8w8bo.jpg&quot; alt=&quot;foamy&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.f-16.net/forum/download/file.php?id=11398&amp;amp;t=1&quot; rel=&quot;noreferrer&quot;&gt;via&lt;/a&gt; F-16.net. &lt;a href=&quot;http://forum.keypublishing.com/showthread.php?128252-Eurofighter-Typhoon-Discussion-and-News-2014/page24&quot; rel=&quot;noreferrer&quot;&gt;More AESA pics&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Fun note, the first F-35 radar pic is of an APG-81 installed on the CATBIRD:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/pJMHs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pJMHs.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://www.youtube.com/watch?v=ao7w-Dzig3c&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Did the F-117 have a radar warning receiver?&lt;/h3&gt;&#xA;&lt;p&gt;It's always been a contentious point. Some say yes, some say no, some say 'I like my job.' In a &lt;a href=&quot;http://f117sfa.org/sfa_newsletter/Newsletter2007-05.pdf&quot; rel=&quot;noreferrer&quot;&gt;lengthy 2007 interview&lt;/a&gt;, Lt. Col. Dale Zelko (the F-117 pilot shot down) declined to reveal whether the RWR (if any) warned him of the missile launch, citing sensitivity. He only reconfirms that he visually tracked the missiles. My &lt;em&gt;guess&lt;/em&gt; is the F-117 may have a limited radar warning capability, but perhaps not in the relevant band. If he or the mission planners had detected and thus been aware of of the radar sites, you'd expect them to plan better routes to avoid the threats.&lt;/p&gt;&#xA;&lt;p&gt;I leave you with a quote from &lt;a href=&quot;http://web.archive.org/web/20141202030156/http://www.defense.gov/transcripts/transcript.aspx?transcriptid=597&quot; rel=&quot;noreferrer&quot;&gt;Maj. Gen. Carlsons' (who flew the F-117) briefing on stealth fighters in 1999, shortly after an F-117 was shot down in Allied Force&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;We started out a long time ago building airplanes that had low observable technology incorporated into their design. The SR-71 was an example of where we took the aerodynamic design and then added some radar absorbing material to the airplane to make it slightly stealthy. And I'll give you a representation of that graphically here in a minute. We went to the &lt;em&gt;&lt;strong&gt;second generation&lt;/strong&gt;&lt;/em&gt; of airplanes and you can see we designed that airplane, the F-117, essentially from the bottom up to be stealthy. &lt;strong&gt;It was crude technology.&lt;/strong&gt; It was developed at a time when we didn't have the modeling and computer power we needed to make the kind of aerodynamic design that we would have liked, but we built one that we thought was very stealthy. And of course, the night that Desert Storm opened the quote from Col. Al Whitley still is famous in the Air Force: &amp;quot;Boy, I hope this stuff really works.&amp;quot; And of course, you know that it did. That isn't exactly what he said.&lt;/p&gt;&#xA;&lt;p&gt;Then we came to the third generation of stealth airplanes. We built the B-2. And of course, by that time, we had the modeling tools and the design tools and the computing power to make an aerodynamic design that was optimum. &lt;strong&gt;And this airplane is [a] much higher altitude, much better performing airplane than the F-117. We were able to eliminate a lot of the radar absorbing material from the structure.&lt;/strong&gt; And by the time we got to the fourth generation, we were able to add supersonic speed, the agility of an F-15, F-16 class airplane and do that with no degradation to the stealth. &lt;strong&gt;In addition to that, we were able to add a number of apertures, in other words, openings in the airplane's surface for antennas, radars and other sensors. And in the F-22, as an example, there are over a hundred of those apertures on the airplane, where if we jump back a couple of generations to the F-117, there are essentially a couple of aperture openings and the rest of them we hide when we go into combat.&lt;/strong&gt; [Emphasis mine.]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Some of the F-22's apertures...&#xA;&lt;a href=&quot;https://i.stack.imgur.com/vEMtF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vEMtF.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zvbWU.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zvbWU.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;a href=&quot;http://www.f-16.net/forum/viewtopic.php?p=38563&amp;amp;sid=0b7f399706b874362e557fe8369ba88b#p38563&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;...whose functionalities were consolidated in the F-35's fewer apertures (some shown here).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1X5pe.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1X5pe.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The F-35's ASQ-239 EW suite, an evolution of the F-22's ALR-94, consolidates 30 senors down to 10.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;[Apologies, pressed for time. This answer will be brief, unlike my previous 29,999 character response.]&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-09-24T07:45:45.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25436" PostTypeId="1" AcceptedAnswerId="25441" CreationDate="2016-02-20T20:09:09.977" Score="4" ViewCount="1335" Body="&lt;p&gt;A view of Davis-Monthan AFB shows thousands of retired aircraft sitting in the desert. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/RsklZ.jpg&quot; alt=&quot;Davis-Monthan AFB&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They go through great lengths to preserve them, even sealing them with an opaque white, hi-tech vinyl plastic compound called &quot;spraylat.&quot;&#xA;&lt;img src=&quot;https://i.stack.imgur.com/9DDn3.jpg&quot; alt=&quot;F-14 in storage&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such an enormous stash of aircraft makes me wonder what they're being kept for. I'm sure there are a few uses for some of them but certainly not all of them. There can't be a big demand for spare parts from obsolete planes. It seems like they would want to scrap them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they being kept in case there is some sort of all-out war and they need cobble together a bunch of F-4's and C-141's to support the air force? Would that even be feasible?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does it somehow cost more to scrap them than the materials are worth?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are they keeping so many retired planes?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Photos retrieved from &lt;a href=&quot;http://www.airplaneboneyards.com/davis-monthan-afb-amarg-airplane-boneyard.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;airplaneboneyards.com&lt;/a&gt;&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-02-20T21:53:01.027" Title="Why does the U.S. keep thousands of retired aircraft in storage?" Tags="&lt;us-air-force&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2016-02-20T23:33:30.963" ContentLicense="CC BY-SA 3.0" />
  <row Id="25437" PostTypeId="1" AcceptedAnswerId="25438" CreationDate="2016-02-20T20:14:48.247" Score="8" ViewCount="12564" Body="&lt;p&gt;Many 737 engines have an accessory gearbox on the 9'o clock position, which is part of why the engine has a flat-bottomed shape. What exactly is an accessory gearbox?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-21T21:03:33.050" LastActivityDate="2019-08-15T00:49:40.280" Title="What is an accessory gearbox?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;boeing-737&gt;&lt;accessory-drives&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25438" PostTypeId="2" ParentId="25437" CreationDate="2016-02-20T20:45:51.533" Score="14" Body="&lt;p&gt;The accessory gearbox is generally driven by the N2 shaft (connecting the high-pressure turbine to the high-pressure compressor) and in turn drives the engine accessories such as generators, hydraulic pumps, oil pumps, etc.  The air turbine starter is also part of this gearbox so during starting the accessory gearbox drives the high-pressure compressor.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This analogous to the serpentine belt on your car, which connects your crankshaft to your cars engine accessories (alternator, water pump, power steering, air conditioning, etc).&lt;/p&gt;&#xA;" OwnerUserId="258" LastActivityDate="2016-02-20T20:45:51.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25439" PostTypeId="5" CreationDate="2016-02-20T21:08:55.583" Score="0" Body="&lt;p&gt;Aircraft designed to patrol in search and surveillance of ships and submarines&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-02-20T21:08:55.583" LastActivityDate="2016-02-20T21:08:55.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25440" PostTypeId="4" CreationDate="2016-02-20T21:08:55.583" Score="0" Body="Maritime Patrol Aircraft" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-02-20T21:08:55.583" LastActivityDate="2016-02-20T21:08:55.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25441" PostTypeId="2" ParentId="25436" CreationDate="2016-02-20T21:42:31.790" Score="2" Body="&lt;p&gt;Some aircraft sold or loaned to outside military forces are built in batches. These aircraft stay in service for a longer period of time than those in the advancing military power, making spares very difficult to obtain and replacement aircraft for those lost in action are going to be impossable to get. I remember on 19 Squadron in RAFG Wildenrath (1979/82), the F4 Phantom was very demanding on which panels and parts would swop between aircraft. The Phantom also went through many states of evolution and when our Govenment decided it was cheaper to buy more F4 aircraft, they had to consider the spares, fitment and training that would be needed to keep our units similar. The Phantoms that were purchased I believe came from the boneyard.&#xA;Of course, the 'all out war' theroy also holds true, if a planet size war was to break out, and you recall all your old pilots.... easier to shove them in aircraft they flew 30-40 years ago than train them in the newer stuff.... going to get very messy up there and replacing pilots/ planes will be a priority, numbers can sometimes win wars. Life expectancy of our frontline pilots were 2/3 sorties at best, Ground crew in fixed bases were 2 days at most..... I miss the old days.&lt;/p&gt;&#xA;" OwnerUserId="13622" LastEditorUserId="13622" LastEditDate="2016-02-20T21:53:01.027" LastActivityDate="2016-02-20T21:53:01.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25442" PostTypeId="1" AcceptedAnswerId="25470" CreationDate="2016-02-20T22:16:26.623" Score="3" ViewCount="680" Body="&lt;p&gt;I don't see it has covers for the flap tracks, so,where are the covers for the flap tracks?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vdv8j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vdv8j.jpg&quot; alt=&quot;wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image taken from the English for Aviation book (Oxford).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is a Vickers VC10&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-23T21:30:03.060" LastActivityDate="2016-02-23T21:30:03.060" Title="Where are the flap track covers on this wing?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25443" PostTypeId="2" ParentId="25442" CreationDate="2016-02-20T23:19:20.427" Score="1" Body="&lt;p&gt;They look like Fowler flaps, like on Hercules c130. If that's the case the flaps run on screwjacks and rollers and slip up and into the wing when cursing. All the mechinisums are shrouded by the flaps themselves when retracted and hence no drag. On takeoff and landing the drag is overcome by takeoff thrust and on landing augmented by airbrakes to reduce landing speed. The flap tracks are in the wing and accessable only when the flaps are extended/ deployed.&lt;/p&gt;&#xA;" OwnerUserId="13622" LastActivityDate="2016-02-20T23:19:20.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25444" PostTypeId="2" ParentId="25056" CreationDate="2016-02-20T23:41:08.047" Score="0" Body="&lt;p&gt;The hole you show in the other post tells me it is not a gun turret. The hole has a small diameter and looks like a series of screw holes around the edge. This could be a sensor or access panel fitment point. The dome itself could be a housing for a strike/ recon camera. It might have fitted to a self contained pod that fitted to an aircraft or be part of a recon aircraft fairing. There is not much to go on and with no access to service parts records you are going to be hard pushed to identify it for sure, hell... it could even be an old truck part.&lt;/p&gt;&#xA;" OwnerUserId="13622" LastActivityDate="2016-02-20T23:41:08.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25445" PostTypeId="2" ParentId="25430" CreationDate="2016-02-20T23:48:59.837" Score="2" Body="&lt;p&gt;&lt;em&gt;This question is a partial duplicate of &lt;a href=&quot;https://aviation.stackexchange.com/q/87/167&quot;&gt;this one&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/2806/167&quot;&gt;this one&lt;/a&gt;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When ATC gives a heading, receives the correct readback, but observes a 10- to 15-degree difference between the actual and intended tracks, does the specialist incorporate this difference into future vectors?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Sometimes.&lt;/strong&gt; The controller issues headings but observes ground track.  If the wind is causing drift, the controller will compensate for it when she provides vectors.  Sometimes, if an aircraft is suitably equipped, a controller will ask for a wind report in order to better judge the winds at altitude.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do approach and traffic separation vectors generally have a healthy margins of error?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Yep&lt;/strong&gt;.  &lt;a href=&quot;https://aviation.stackexchange.com/q/2806/167&quot;&gt;See here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does apparent compass deviation or directional gyro precession factor into vectors that ATC issues?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It's up to the pilot&lt;/strong&gt;, not the controller, to correct for compass deviation (since only the pilot can see the compass correction card inside the aircraft) and gyro precession (since only the pilot can turn the little knob to reset the gyro).&lt;/p&gt;&#xA;" OwnerUserId="167" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-20T23:48:59.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25446" PostTypeId="1" AcceptedAnswerId="25449" CreationDate="2016-02-21T00:02:56.030" Score="8" ViewCount="580" Body="&lt;p&gt;&lt;a href=&quot;http://tfmlearning.faa.gov/Publications/atpubs/ATC/atc0506.html&quot;&gt;Order JO 7110.65T Section 6 Part 5-6-1&lt;/a&gt; says&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Vector aircraft:&lt;br&gt;&#xA;  a. In controlled airspace for separation, safety, noise abatement, operational advantage, &lt;strong&gt;confidence maneuver&lt;/strong&gt;, or when a pilot requests. Allow aircraft operating on an RNAV route to remain on their own navigation to the extent possible. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is a confidence maneuver?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="167" LastActivityDate="2016-02-29T14:39:02.867" Title="What is a &quot;confidence maneuver&quot;?" Tags="&lt;air-traffic-control&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25447" PostTypeId="1" AcceptedAnswerId="25510" CreationDate="2016-02-21T00:05:33.020" Score="11" ViewCount="9487" Body="&lt;p&gt;Suppose a general aviation aircraft is operating VFR under part 91. When they call ATC they'd normally use their tail number as the call sign. Something like &quot;November 1-2-3 Foxtrot Uniform.&quot; What if they called up as &quot;little piggy 27?&quot; Are there guidelines or regulations about this? Does a custom call sign require anything or can you just make one up?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="1696" LastEditDate="2016-02-24T16:13:18.040" LastActivityDate="2016-02-24T16:13:18.040" Title="What are the guidelines for call signs for aircraft dealing with US ATC?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;call-sign&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25448" PostTypeId="1" AcceptedAnswerId="25450" CreationDate="2016-02-21T00:30:22.640" Score="7" ViewCount="335" Body="&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airlines&quot;&gt;Wikipedia &gt; List of Airlines&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are around 5000 airlines with IATA codes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airline_codes&quot;&gt;Wikipedia &gt; List of Airlines Codes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;IATA airline designators [..] are two-character codes [..]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;after an airline is delisted, the code becomes available for reuse after six months&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The last quotation suggests that no two airline companies can share the same IATA code.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the characters allowed, a two-character codes can make $26^2=676$ combinations or eventually $36^2=1296$ combinations. It would take at least 71 different characters authorized to register 5000 companies ($71^2=5041$). It is unlikely that 71 or more characters are authorized. It seems paradoxical to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I misunderstanding?&lt;/p&gt;&#xA;" OwnerUserId="13623" LastEditorUserId="1696" LastEditDate="2016-02-21T01:41:18.500" LastActivityDate="2016-02-21T01:41:18.500" Title="Are there 5000+ companies with IATA (two-character) codes?" Tags="&lt;commercial-aviation&gt;&lt;airlines&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25449" PostTypeId="2" ParentId="25446" CreationDate="2016-02-21T00:35:24.613" Score="7" Body="&lt;p&gt;As quoted from the entry in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;nofollow&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CONFIDENCE MANEUVER− A confidence maneuver&#xA;  consists of one or more turns, a climb or&#xA;  descent, or other maneuver to determine if the pilot&#xA;  in command (PIC) is able to receive and comply with&#xA;  ATC instructions. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This could be useful if the controller suspects a hijacking, hypoxia, radio failure, or other situations that would compromise reception and execution of ATC instructions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the best example of an implementation of this would be when ATC suspects a partial aircraft radio failure; a confidence maneuver vector might enable ATC to determine that the pilot was still able to receive instructions, though aircraft radio transmission might be compromised.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-29T14:39:02.867" LastActivityDate="2016-02-29T14:39:02.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25450" PostTypeId="2" ParentId="25448" CreationDate="2016-02-21T00:51:51.370" Score="6" Body="&lt;p&gt;It's obviously an error in that Wikipedia page. The &quot;5000 airlines with IATA codes&quot; text actually links to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airline_codes&quot;&gt;https://en.wikipedia.org/wiki/List_of_airline_codes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which lists lots of airlines (over 6000), but most of those have ICAO (3 letter) codes, but not IATA (2 letter) codes.&lt;/p&gt;&#xA;" OwnerUserId="3313" LastActivityDate="2016-02-21T00:51:51.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25451" PostTypeId="2" ParentId="25447" CreationDate="2016-02-21T03:04:52.603" Score="2" Body="&lt;p&gt;Operator call signs are generally established with the FAA&gt;&#xA;In addition, operators can establish local call signs with their ATC facility.&#xA;E.g. News Chopper 10.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has established aircraft types in call signs at well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can't just make up a call sign. &lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-02-21T03:04:52.603" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25452" PostTypeId="1" AcceptedAnswerId="25456" CreationDate="2016-02-21T05:30:51.887" Score="2" ViewCount="9277" Body="&lt;p&gt;A car requires only 1 single driver. Why do airplanes require 3 pilots given that each pilot does not come cheap to the airline? Furthermore, a plane can go on auto-pilot while a car cannot. Could there be more room for efficiency by reducing the number of pilots needed?&lt;/p&gt;&#xA;" OwnerUserId="13625" LastActivityDate="2018-07-17T02:48:41.470" Title="Why does an airplane require 3 pilots on board?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;pilots&gt;&lt;airlines&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25454" PostTypeId="1" AcceptedAnswerId="25455" CreationDate="2016-02-21T05:46:14.623" Score="19" ViewCount="1049" Body="&lt;p&gt;I've been reading material about the &lt;a href=&quot;http://www.perlanproject.org&quot;&gt;Perlan II experimental glider&lt;/a&gt;. They hope to take it up to 90,000 feet  -- higher even than an SR-71 BlackBird.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the Perlan II is just a glider. Can it really just climb thermals up to that level? Is there something special about its aerodynamic design that lets it do that -- or are all gliders capable of climbing as high as possible, with only the  heat and oxygen needs of the human occupants being the limiting factor? Or is it just me that finds it odd that a glider can climb higher than  a powered aircraft?&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2016-02-21T21:34:55.640" LastActivityDate="2016-02-21T21:34:55.640" Title="How can the Perlan II glider climb to 90,000 feet?" Tags="&lt;glider&gt;&lt;experimental-aircraft&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25455" PostTypeId="2" ParentId="25454" CreationDate="2016-02-21T06:28:04.760" Score="19" Body="&lt;p&gt;Perlan II will climb to extreme altitudes on wave lift, not thermal lift. Wave lift is created when strong winds blow approximately perpendicular to a mountain range, and the wind speed increases steadily with altitude. This creates a standing wave in the atmosphere, kind of like the ripple behind a rock in a fast moving stream of water. On the leading edge of the wave, air is moving up, and that's where gliders fly. Standing waves can reach very high into the atomosphere, which is why Perlan II is expected to reach 90,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perlan II is different from normal gliders in that its wing is optimized for minimum sink, instead of best glide ratio. It's meant to float along while losing a minimum of altitude, which makes sense if it's going to fly in nothing but wave. Normal gliders are usually optimized more for gliding long distances, for which glide ratio is more important than minimum sink. Interestingly, Perlan II's wing looks a lot like RC model glider wings, which are also optimized for minimum sink, since RC gliders don't typically fly cross country.&lt;/p&gt;&#xA;" OwnerUserId="9195" LastActivityDate="2016-02-21T06:28:04.760" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25456" PostTypeId="2" ParentId="25452" CreationDate="2016-02-21T06:33:19.960" Score="24" Body="&lt;p&gt;Actually, for all but very long haul flights, airline aircraft only require two pilots, a Captain and a First Officer. For those long haul flights that exceed the duty time in a pilot seat, a relief pilot is also carried.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older aircraft often also had a flight engineer. Technically speaking the f.e. wasn't usually required to be a pilot, but he was a very necessary crew member. You could say that airlines became more efficient crew-wise when they moved from 3-man cockpit crews to 2-man cockpit crews. For example, the 747-100/200 series uses 3-man crews, but the 747-400 uses 2-man crews. The change was made possible by using automation and instrumentation that wasn't available when the first 747 models came out. Indirectly the increase in engine reliability also helped. If you lost an engine in an 3-man crew 747, the typical manner of handling the loss was to have the first officer fly the airplane while the captain and the f.e. worked the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To illustrate the increase in automation, the 747-100/200 series had, typically, seven or nine fuel tanks, and there was a fuel burn schedule that had to be followed to keep the structural stresses and balances between different levels of the tanks within limits. The f.e. took care of that, doing it manually by throwing switches on his panel. The 747-400 and follow on models do that automatically by computer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the number in the cockpit crew is determined by safety. There's the basic consideration that if you had only one pilot, and that pilot died or otherwise was disabled, that might well be catastrophic. Beyond that, though, there's the matter of what all has to be done and for how long. Pilots make mistakes, and the longer they've on duty, the more mistakes they make. And if an emergency occurs, the work load can get very high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can't reasonably compare an aircraft to a car for at least two reasons. First, a car is moving in only two dimensions, an aircraft in three. Second, a car can stop moving, an aircraft can't; it has to keep moving. Let's say your car loses power. Usually that won't result in anything more than inconvenience. If your aircraft loses power, you've got a much more serious problem. Most airline aircraft have at least two engines. Losing one isn't going cause a crash in most two engine aircraft, losing all power will.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-02-21T08:54:17.960" LastActivityDate="2016-02-21T08:54:17.960" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25457" PostTypeId="2" ParentId="25452" CreationDate="2016-02-21T06:39:09.480" Score="7" Body="&lt;p&gt;Most of the commercial airlines now require only two pilots- a captain and a first officer. It is in a large part, regulatory (GA and combat aircraft have only a single pilot). It is perfectly &lt;em&gt;possible&lt;/em&gt; to &lt;a href=&quot;https://aviation.stackexchange.com/questions/23068/how-many-pilots-are-required-in-an-airbus-a380&quot;&gt;fly a transport aircraft with a single pilot&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, there have been calls for &lt;a href=&quot;http://www.theguardian.com/money/2010/sep/08/ryanair-axe-unnecessary-co-pilots&quot; rel=&quot;nofollow noreferrer&quot;&gt;eliminating the second pilot&lt;/a&gt;. There are some points though.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The roles of the captain and first officer are complementary, not identical; though it is perfectly possible to have only a single pilot, having two helps.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One important reason is safety/redundancy- If something &lt;a href=&quot;http://edition.cnn.com/2015/10/05/us/american-airlines-pilot-death/&quot; rel=&quot;nofollow noreferrer&quot;&gt;happens to a pilot&lt;/a&gt; en route, the other one can take over and land safely. this safety by redundancy extends to all aircraft systems.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In long haul flights, two (or more, usually) pilots are required (both practically and by regulation).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another point is that autolanding is not possible in all the airports. it needs the necessary ILS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;One problem with comparing aircraft with cars (or other surface vehicles, like trains) is that the effects of losing control and power in these cases is completely different. A car can simply go hit something and stop- that is not an option with an aircraft; it'll fall. Trains usually have a dead man's switch that'll apply emergency brakes if the pilot's presence is not felt.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-06-24T14:15:46.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25458" PostTypeId="2" ParentId="25424" CreationDate="2016-02-21T08:54:00.127" Score="3" Body="&lt;p&gt;To further illustrate @mins' excellent explanation, here are some animations and simulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Quick Raytheon marketing vid of the Air and Missile Defense Radar, a next-gen AESA for destroyers. It provides volume search, horizon search, periscope search, ballistic missile tracking, and missile guidance and target illumination, among other functions. Go to [0:30]:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/yNkUx9vguQ8?t=30?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another Raytheon AMDR illustration. Go to [1:00]:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/K1-_4tfWR4c?t=60?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third AMDR animation by Lockheed Martin:&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/UfMYslk29R0?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-35's APG-81 AESA (an advanced derivative of the F-22's radar) is demoed here in a marketing vid by Northrop Grumman, the maker. Interesting bit at [1:00].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/wIwAOupjMeM?t=60?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See here for a &lt;a href=&quot;https://www.reddit.com/r/Warships/comments/3yg08p/ever_wondered_how_active_electronically_scanned/&quot; rel=&quot;nofollow&quot;&gt;simple 15 element linear array&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2016-02-21T08:59:02.673" LastActivityDate="2016-02-21T08:59:02.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25459" PostTypeId="1" AcceptedAnswerId="25461" CreationDate="2016-02-21T09:27:15.647" Score="8" ViewCount="505" Body="&lt;p&gt;What is minimal altitude that aircraft (rocket?) can fly above any country without any permission? I mean, at what altitude ends country's airspace?&lt;/p&gt;&#xA;" OwnerUserId="12259" LastActivityDate="2020-09-15T09:40:00.490" Title="What is minimal altitude that aircraft (rocket?) can fly above any country without any permission?" Tags="&lt;airspace&gt;&lt;altitude&gt;&lt;high-altitude&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25461" PostTypeId="2" ParentId="25459" CreationDate="2016-02-21T13:32:14.230" Score="7" Body="&lt;p&gt;Actually, what you're asking are two different questions- According to ICAO ( ICAO Annex 11: Air Traffic Services), Class G airspace is uncontrolled and aircraft can fly in the without ATC permission. The definition if Class G is left to the regulatory authorities of individual countries (in US, it is where the other airspace classes are undefined). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where does the airspace of the country end is a completely different one and as of now, there is no agreed definition. The United Nations General Assembly Committe on Peaceful Uses of Outer space is &lt;a href=&quot;http://www.unoosa.org/pdf/limited/c2/AC105_C2_2012_DEF_L01E.pdf&quot;&gt;still in the process of defining what exactly an outer space is&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-21T13:32:14.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25462" PostTypeId="1" CreationDate="2016-02-21T13:56:10.947" Score="2" ViewCount="73" Body="&lt;p&gt;I am a private pilot who has not flown in 30+ years, but want to start again.  I'm a little concerned about how airspace and avionics may have changed.  Will be starting with CFI next week.  Can anyone give me an overview of what I might encounter? Cessna 172, SEL, Private no IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;M Walker&lt;/p&gt;&#xA;" OwnerUserId="13630" LastEditorUserId="3201" LastEditDate="2016-02-21T14:10:19.580" LastActivityDate="2016-02-22T02:15:23.793" Title="Currency retraining" Tags="&lt;usa&gt;&lt;airspace&gt;&lt;avionics&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-02-22T06:23:19.643" ContentLicense="CC BY-SA 3.0" />
  <row Id="25464" PostTypeId="1" CreationDate="2016-02-21T15:41:21.223" Score="1" ViewCount="349" Body="&lt;p&gt;With several instances of pilots being subjected to laser lights being shone on them, I wonder if the FAA is actually doing something about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's easier said than done to stop people on the ground from shining their laser lights. Maybe a preventive strategy is better. With a host of eyewear available which minimise the risk of laser light, I am curious as to what the FAA and other similar authorities are doing about it.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="62" LastEditDate="2016-02-22T22:57:14.663" LastActivityDate="2016-09-01T18:53:00.887" Title="Does the FAA advise or require pilots to wear eyewear designed to protect them from lasers?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;pilots&gt;&lt;laser-illumination&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25465" PostTypeId="1" AcceptedAnswerId="25467" CreationDate="2016-02-21T15:47:59.810" Score="16" ViewCount="8248" Body="&lt;p&gt;When reading the specifications of a jet aircraft anywhere on the Internet, it usually states that its engine produces X pounds of &quot;dry thrust&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is it called &quot;Dry&quot; Thrust? As opposed to what?&lt;/p&gt;&#xA;" OwnerUserId="889" LastEditorUserId="1467" LastEditDate="2016-02-22T08:25:50.593" LastActivityDate="2016-02-22T19:25:19.583" Title="Why is it called &quot;Dry Thrust&quot;?" Tags="&lt;jet-engine&gt;&lt;terminology&gt;&lt;jet&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25466" PostTypeId="2" ParentId="25465" CreationDate="2016-02-21T16:00:45.390" Score="7" Body="&lt;p&gt;Dry thrust refers to an afterburning engine running without &lt;a href=&quot;https://en.wikipedia.org/wiki/Afterburner&quot;&gt;afterburner&lt;/a&gt;.  The figures you mention usually refer to the maximum thrust without afterburner.&lt;/p&gt;&#xA;" OwnerUserId="2923" LastActivityDate="2016-02-21T16:00:45.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25467" PostTypeId="2" ParentId="25465" CreationDate="2016-02-21T16:01:23.893" Score="27" Body="&lt;p&gt;Dry thrust usually means the non-augumented thrust i.e. thrust without the use of afterburners or liquid injection. The maximum thrust produced by jet engines w/o afterburner is sometimes called military thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thrust of a jet eingine can be increased by using methods like water(+methonol) injection (mostly in older turbojet engines) or by using afterburners (reheat). In such cases, the (higher) thrust produced is called wet thrust. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="39" LastEditDate="2016-02-22T04:46:36.770" LastActivityDate="2016-02-22T04:46:36.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25468" PostTypeId="2" ParentId="25464" CreationDate="2016-02-21T16:46:17.670" Score="4" Body="&lt;p&gt;I'm not aware of FAA (or any other regulatory body) recommending protective eyewear for lasers. &lt;a href=&quot;https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/laser_hazards_web.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA safety Advisory&lt;/a&gt; doesn't include them. There are a couple of problems with using protective eyewear for lasers:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The eyewear is usually wavelength sensitive; The pilot has to wear the correct eyewear that blocks the incoming laser beam; he/she should know the wavelength of incoming laser.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The protective eyewear filters (atleast most) of the incoming light in that wavelength. This may affect the normal sight of the flight crew.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Due to these reasons, the regulatory authorities are more concerned with procedural changes that protective wear. From &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_01_10/3/&quot; rel=&quot;nofollow&quot;&gt;Boeing's protection against lasers&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... however, airlines should consider the drawbacks that are associated with them. Filtering light reduces the total amount of light entering the eye, which can adversely affect normal viewing, ... . In addition, filtering green light can remove some green flight symbology on flight deck displays and change the appearance of some of the other colors used. As a result, protective glasses should be used with care. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="755" LastEditDate="2016-09-01T18:53:00.887" LastActivityDate="2016-09-01T18:53:00.887" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25469" PostTypeId="2" ParentId="25459" CreationDate="2016-02-21T18:33:49.400" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What is minimal altitude that aircraft (rocket?) can fly above any country without any permission?&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;100 km, probably&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the Kármán line, at an altitude of 100 km (62 mi) above sea level,[7][8] is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the Outer Space Treaty, which was passed by the United Nations in 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;- Wikipedia&lt;/p&gt;&#xA;" OwnerUserId="1289" LastActivityDate="2016-02-21T18:33:49.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25470" PostTypeId="2" ParentId="25442" CreationDate="2016-02-21T21:21:26.597" Score="7" Body="&lt;p&gt;From the Vickers VC-10 repair manual:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w9WVF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w9WVF.jpg&quot; alt=&quot;General arrangement of VC-10 wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;General arrangement of VC-10 wing (picture &lt;a href=&quot;http://www.vc10.net/images/wing_srm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the labelling of the Shock bodies as &quot;flap rail fairings&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flap tracks were inside the Küchemann bodies and the flaps were between them. This produced gaps between the five flap segments which made them less effective than the modern design of uninterrupted flaps with the flap tracks below them.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-21T21:21:26.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25471" PostTypeId="2" ParentId="25462" CreationDate="2016-02-22T02:15:23.793" Score="0" Body="&lt;p&gt;To regain your currency there are a few things you need to do legally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Medical:&lt;/strong&gt; The first thing you will need to do is get your medical cert back, to fly with a CFI this is not mandatory since they are technically acting as pilot in command but you will need it before you can act as pilot in command. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bi-Annual:&lt;/strong&gt; You will be required to do your bi-annual flight review which legally is one hour of ground instruction and one hour of flight time instruction to become current. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Landings:&lt;/strong&gt; Although you will most likely knock this out during your bi-annual, before you carry passengers you will need to do 3 TO/LD for day currency and 3 full stop night TO/LD for night currency. Since you may need a few hours of instruction to feel comfortable I would set up at least 1 night hour to get these landings in. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of what has changed in the last 30 years...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;nofollow&quot;&gt;172&lt;/a&gt; is still a 172 and the yoke is still in the same place. In terms of what you will encounter in the cockpit this will vary from plane to plane. Lots of trainers are old planes and or set up as they were more or less 30 years ago. The biggest difference you will find is the role and inclusion of GPS. While its not required (yet...) a lot of planes have the common &lt;a href=&quot;https://buy.garmin.com/en-US/US/in-the-air/discontinued/gns-430w/prod301.html&quot; rel=&quot;nofollow&quot;&gt;Garmin 430&lt;/a&gt; or 530 units and some planes out there may even have a full &lt;a href=&quot;https://en.wikipedia.org/wiki/Garmin_G1000&quot; rel=&quot;nofollow&quot;&gt;G1000&lt;/a&gt; setup. Much of this depends where you rent from. You will still be able to get all your paper charts as you once could but many people are moving into the tablet/e-flight bag revolution which can really revolutionize how you fly. You may want to check out &lt;a href=&quot;http://foreflight.com/&quot; rel=&quot;nofollow&quot;&gt;ForeFlight&lt;/a&gt; and the like to see what they have to offer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA offers lots of &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/&quot; rel=&quot;nofollow&quot;&gt;free handbooks that can be found here&lt;/a&gt;. Of particular interest might be Pilot's Handbook of Aeronautical Knowledge, Aeronautical Information Manual, and this &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot; rel=&quot;nofollow&quot;&gt;overview on airspaces&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-02-22T02:15:23.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25472" PostTypeId="1" CreationDate="2016-02-22T03:56:08.250" Score="1" ViewCount="132" Body="&lt;p&gt;As it is generally seen, 2 engines are more efficient than 4 engines. So, can we have so powerful engines to design an aircraft as big as A380 with 2 engines?&lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2016-02-22T03:56:08.250" Title="Is it possible to design an aircraft as big as A380 with 2 engines?" Tags="&lt;aircraft-design&gt;&lt;engine&gt;&lt;airbus-a380&gt;" AnswerCount="0" CommentCount="2" FavoriteCount="2" ClosedDate="2016-02-22T07:07:35.773" ContentLicense="CC BY-SA 3.0" />
  <row Id="25473" PostTypeId="1" AcceptedAnswerId="25513" CreationDate="2016-02-22T04:36:35.447" Score="7" ViewCount="14547" Body="&lt;p&gt;When we use this awesome instrument for navigation (not only for ILS/LOC), it is said that there is no reverse sensing (except for back course thing). I kind of understand why pilots are confused when we use conventional VOR, and now I want to know why there is no reverse sensing? How does it work? Can anyone help me out?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="12220" LastEditDate="2016-02-29T14:47:20.013" LastActivityDate="2016-02-29T14:47:20.013" Title="Why is there no &quot;reverse sensing&quot; on a horizontal situation indicator (HSI)?" Tags="&lt;vor&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25475" PostTypeId="1" AcceptedAnswerId="25476" CreationDate="2016-02-22T07:00:34.587" Score="9" ViewCount="3408" Body="&lt;p&gt;I am trying to work out what engine power setting is used during the cruise phase of commercial flights but I can't find anything about it in the usual spots. Anyone have any idea what percent of engine power is used? Like 50% engine power maybe?&lt;/p&gt;&#xA;" OwnerUserId="13643" LastEditorUserId="62" LastEditDate="2016-07-31T16:24:17.217" LastActivityDate="2016-07-31T16:24:17.217" Title="What engine power setting is used during cruise?" Tags="&lt;airliner&gt;&lt;jet-engine&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25476" PostTypeId="2" ParentId="25475" CreationDate="2016-02-22T07:17:54.100" Score="13" Body="&lt;p&gt;At first, I was tempted to close the question as a duplicate, but then I could not find one that would address the point directly. But there are many questions and answers on this site which allow one to cobble together the answer:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12541/why-are-many-jet-aircraft-designed-to-cruise-around-fl350-370/12544#12544&quot;&gt;Why are many jet aircraft designed to cruise around FL350-370?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21820/why-has-the-maximum-service-ceiling-of-boeing-and-airbus-products-remained-about?lq=1&quot;&gt;Why has the maximum service ceiling of Boeing and Airbus products remained about the same for 30 years?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes&quot;&gt;Why do jet engines get better fuel efficiency at high altitudes?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/14099/how-much-fuel-does-it-take-to-start-land-an-aircraft-compared-to-normal-flight?lq=1&quot;&gt;How much fuel does it take to start/land an aircraft, compared to normal flight?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21307/what-is-the-one-engine-inoperative-maximum-range-flight-configuration?lq=1&quot;&gt;What is the one-engine-inoperative maximum range flight configuration?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;To save you to read through all linked answers, here is the gist of it: Jet engines are run at close to their maximum power during cruise, but their thrust is much less at altitude due to lower air density. Airliners want to fly as high as possible to fly faster for the same drag and to gain efficiency, and their designs are balanced to achieve reasonable take-off distances and good cruise performance at close to maximum thrust.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-22T07:17:54.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25477" PostTypeId="2" ParentId="12806" CreationDate="2016-02-22T07:19:13.380" Score="23" Body="&lt;p&gt;As a long time ramp agent for Delta and Southwest Airlines, I can tell you they are a critically necessary element to ground crew safety. Not only do they tell you the impeller in spinning, but once the human eye can no longer identify the swirl pattern, it is spinning with enough speed to be an induction hazard (it can suck you in).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When parking an airliner, the crew lead guides the aircraft using aircraft marshaling wands. When he/she turns both tip toward each other, the crew set chocks around the wheels. Then NOTHING happens until that crew lead can see those spinning spirals clearly in all engines. Then and ONLY then, does that lead clear the crew to continue operations and begins comms with the flight crew. &lt;/p&gt;&#xA;" OwnerUserId="13644" LastEditorUserId="65" LastEditDate="2016-02-23T02:30:34.083" LastActivityDate="2016-02-23T02:30:34.083" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25478" PostTypeId="1" CreationDate="2016-02-22T08:13:50.627" Score="3" ViewCount="699" Body="&lt;p&gt;Here in my home country (Hong Kong), all air traffic controllers are required  to obtain a PPL as part of their training. The reason being, if the controllers can better imagine a pilot's perspective, they can better accommodate and provide assistance to pilots. I don't think they are required to keep the license current, but sure they need to pass all PPL exams.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this requirement common around the world? (Note that I intentionally do not specify which country or jurisdiction. I'm looking for an answer which lists the countries which have this requirement.)&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-22T09:17:34.247" LastActivityDate="2016-02-22T09:17:34.247" Title="Are air traffic controllers required to obtain a pilot license?" Tags="&lt;air-traffic-control&gt;&lt;flight-training&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2016-02-22T13:43:12.470" ContentLicense="CC BY-SA 3.0" />
  <row Id="25479" PostTypeId="2" ParentId="25478" CreationDate="2016-02-22T08:32:45.173" Score="1" Body="&lt;p&gt;No, there is no such requirement here in Germany.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2016-02-22T08:32:45.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25480" PostTypeId="2" ParentId="25473" CreationDate="2016-02-22T09:19:16.417" Score="4" Body="&lt;p&gt;Essentially because you turn the instrument upside down and read it normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the back-course, the signals are reversed. That is a property of the ILS signal. When using traditional ILS/LOC instrument, the needle moves right when it senses more of the right signal, but since the signal is now on the left, you get reverse sensing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the HSI, the needle still moves right when it senses more of the right &lt;em&gt;relative to the arrow&lt;/em&gt; when it senses more of the right signal. However, the needle points in the selected heading and is rotated with compass. So when you fly a back-course, you dial the normal course of the ILS and since you actually fly opposite direction, the arrow points down and right relative to it is left. And you get normal sensing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For VOR, the situation is similar. In VOR, the needle moves normally if you are flying the heading selected and it moves in reverse if you are flying the opposite heading. And when you are flying the opposite heading, the HSI arrow points down, reverting the sensing back to normal.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-02-22T13:51:16.590" LastActivityDate="2016-02-22T13:51:16.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25481" PostTypeId="2" ParentId="25473" CreationDate="2016-02-22T10:05:16.817" Score="-2" Body="&lt;p&gt;I guess what the OP means is that why there is no &quot;reverse sensing&quot; switch on the instrument. The answer being rather simple - to avoid the pilots making a mistake when they forget to flip the switch to the correct position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can always flip the OBS 180 degrees to make that change. I like to think of the HSI as always sensing &quot;positively&quot;. &lt;em&gt;You're just tracking the wrong side.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instrument always tells you the relative position to the VOR course / localizer, it is up to the pilot to manipulate the plane to the desired position. It's reverse &lt;em&gt;tracking&lt;/em&gt;, not reverse &lt;em&gt;sensing&lt;/em&gt;. The instrument tells you your deviation from the selected course, it has been and will be doing that all the time. &lt;em&gt;If your selected course is 180 degrees off, following the rules of geometry, you'll naturally end up switching left and right.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is worth noting that the autopilots have an &quot;reverse course tracking&quot; switch:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/mFc7Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mFc7Z.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want an instrument which tells you how to fly to intercept the course, it is called a &lt;strong&gt;Flight Director&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-02-23T13:15:01.477" LastActivityDate="2016-02-23T13:15:01.477" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25482" PostTypeId="1" CreationDate="2016-02-22T11:46:33.403" Score="4" ViewCount="184" Body="&lt;p&gt;How to calculate the force of hot air balloon envelope fabric?&#xA;and how to select a fabric which can bear this force?&#xA;For example, a spherality balloon:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$r=10~m$&lt;/li&gt;&#xA;&lt;li&gt;$T_1=100~°C$&lt;/li&gt;&#xA;&lt;li&gt;$ρ_1=0.95~kg/m^3$&lt;/li&gt;&#xA;&lt;li&gt;$T_2=20~°C$&lt;/li&gt;&#xA;&lt;li&gt;$ρ_2=1.25~kg/m^3$&lt;/li&gt;&#xA;&lt;li&gt;$m=1000~kg$&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Where: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$r$ is the  radii of the balloon, in m &lt;/li&gt;&#xA;&lt;li&gt;$T_1$ is the temperature of balloon inside atmosphere, in Celsius &lt;/li&gt;&#xA;&lt;li&gt;$ρ_1$ is the density of the balloon inside atmosphere, in  kg/m3&lt;/li&gt;&#xA;&lt;li&gt;$T_2$ is the temperature of balloon outside atmosphere, in Celsius &lt;/li&gt;&#xA;&lt;li&gt;$ρ_2$ is the density of the balloon outside atmosphere, in  kg/m3&lt;/li&gt;&#xA;&lt;li&gt;$m$ is the total weight of the balloon(including balloon all equipment and persons)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13647" LastEditorUserId="1696" LastEditDate="2016-07-05T19:36:04.073" LastActivityDate="2016-07-05T19:36:04.073" Title="How to calculate the force exerted by pressure on hot air balloon envelope fabric?" Tags="&lt;balloon&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-02-22T18:19:34.243" ContentLicense="CC BY-SA 3.0" />
  <row Id="25483" PostTypeId="2" ParentId="25312" CreationDate="2016-02-22T15:27:45.310" Score="5" Body="&lt;h1&gt;Appendix&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I exceeded the 30,000 character limit in my above answer. Here are some additional figures and quotes.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;http://csbaonline.org/publications/2015/04/trends-in-air-to-air-combat-implications-for-future-air-superiority/&quot; rel=&quot;noreferrer&quot;&gt;CSBA&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;h3&gt;On dogfighting and WVR:&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Hitting an alerted opponent was really hard, according to aces in WWI and WWII. ALL viewed &lt;strong&gt;maneuvering combat as high risk, low payoff.&lt;/strong&gt; &lt;/li&gt;&#xA;&lt;li&gt;Ericc Hartmann, Gerhard Barkhorn (300+ kills each on the eastern front in WWII) developed &quot;ambush tactics&quot;: position of advantage, swoop in, shoot, exit, reassess, repeat.&lt;/li&gt;&#xA;&lt;li&gt;Richard Bong and Thomas McGuire developed similar tactics (&quot;boom and zoom&quot;)&lt;/li&gt;&#xA;&lt;li&gt;Post-Vietnam Red Baron air reports: &lt;strong&gt;80% of kills resulted from attacking unalerted victims. Superior SA was key.&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Desert Storm&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ROE - contact is declared hostile if...&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;AWACS declares contact hostile&lt;/li&gt;&#xA;&lt;li&gt;2 sources of ID (eg, visual, Mode 4 IFF, non-cooperative target ID available on F-15Cs)&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;Coalition killed ~33 Iraqi a/c&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;27/33 - AWACS provided targeting info. &lt;/li&gt;&#xA;&lt;li&gt;16/33 - BVR kills &lt;/li&gt;&#xA;&lt;li&gt;17/33 - WVR engagements, only 5 included any significant ACM. Long range detection afforded pilots time to position themselves advantageously for shots &lt;em&gt;without&lt;/em&gt; pulling significant g'.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;BVR engagements&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Longest detection range was 42 nmi (basically the F-15C's radar limit). Longest missile shot was 16 nmi---10 nmi was average---AIM-7 missile limitation. The longer ranged AMRAAMs weren't available yet. Crews often just waited to get into range.&lt;/li&gt;&#xA;&lt;li&gt;Shot 28 AIM-7s in BVR engagements. 22 hit the target or fireball.... new AIM-7s were nearly 10x more reliable than 1960s AIM-7s in Vietnam.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;Speed&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;US aircrews never exceeded 650 knots.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h3&gt;Misc&lt;/h3&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Longest BVR missile kill: 62 nmi in mid 1980s by Iranian F-14 with Phoenix missiles.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7394" LastActivityDate="2016-02-22T15:27:45.310" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25484" PostTypeId="1" AcceptedAnswerId="25496" CreationDate="2016-02-22T15:34:47.887" Score="18" ViewCount="13390" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/25454/how-can-the-perlan-ii-glider-climb-to-90-000-feet#comment61190_25455&quot;&gt;this comment&lt;/a&gt; a brief explanation is made of the differences between Max Glide Ratio and Min Sink Ratio:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sink rate is how much altitude you lose over time, for example, how many feet per second. So minimum sink is the lowest sink rate you can get. Glide ratio is how much distance you can travel per given loss of altitude, for example, how many feet per feet. So max glide ratio is the shallowest angle you can glide at. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;However, I don't understand how the &lt;code&gt;lowest sink rate you can get&lt;/code&gt; isn't the same as the &lt;code&gt;shallowest angle you can glide at&lt;/code&gt;. If I can design wing &lt;em&gt;A&lt;/em&gt; to sink at only 1 foot per minute, wouldn't that automatically get me a longer glide ratio from altitude X than wing &lt;em&gt;B&lt;/em&gt; that sinks at 2 feet per minute?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2017-02-03T03:04:30.713" Title="What is the difference between the Maximum Glide and Minimum Sink ratios?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing&gt;&lt;descent&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25485" PostTypeId="2" ParentId="25484" CreationDate="2016-02-22T15:53:30.683" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;However, I don't understand how the &lt;code&gt;lowest sink rate you can get&lt;/code&gt; isn't the same as the &lt;code&gt;shallowest angle you can glide at&lt;/code&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Look at a &lt;a href=&quot;https://en.wikipedia.org/wiki/Polar_curve_%28aviation%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Polar Curve&lt;/a&gt;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZFmN6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZFmN6.jpg&quot; alt=&quot;Polar curve&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;code&gt;lowest sink rate you can get&lt;/code&gt; is the maximum value of the curve, as illustrated in this image taken from the wiki article above:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fWTbj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fWTbj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;code&gt;shallowest angle you can glide at&lt;/code&gt; is given by the tangent to the curve that passes through the origin (another image from the wiki article)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sXCGP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sXCGP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If I can design one wing to sink at only 1 foot per minute, wouldn't that automatically get me a longer glide ratio from altitude X, than another wing that sinks at 2 feet per minute?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As we see from the images above, the answer is not a clear yes/no, because it depends on the Glide Polar of the aircraft. Having a wing that sinks at 1 ft/min vs another that sinks at 2 fts/min is no guarantee that the polar is shifted upwards, giving you a better glide ratio. It will depend also on wing loading, as Peter wrote in &lt;a href=&quot;https://aviation.stackexchange.com/a/3624/1467&quot;&gt;this answer&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-02-22T16:01:32.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25486" PostTypeId="1" AcceptedAnswerId="25491" CreationDate="2016-02-22T16:14:01.020" Score="3" ViewCount="2175" Body="&lt;p&gt;Consider the following scenario: A crew experiences a flat/burst tyre above V1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it possible, in some type of aircraft, to change it while in flight? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might include, but not limited to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;access the landing gear compartment&lt;/li&gt;&#xA;&lt;li&gt;access hydraulic operated equipment&lt;/li&gt;&#xA;&lt;li&gt;changing the damaged tyre&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="5517" LastEditDate="2016-02-22T16:24:05.733" LastActivityDate="2016-02-22T18:16:57.913" Title="Is it possible to change/repair an aircraft tire while in flight?" Tags="&lt;aircraft-maintenance&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25487" PostTypeId="2" ParentId="25486" CreationDate="2016-02-22T17:01:46.840" Score="3" Body="&lt;p&gt;Normally the answer would be no, but if you have&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;an airplane with a low minimum speed and plenty of gas,&lt;/li&gt;&#xA;&lt;li&gt;a fast pickup truck,&lt;/li&gt;&#xA;&lt;li&gt;a very, very long runway and&lt;/li&gt;&#xA;&lt;li&gt;calm weather,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;you can have someone get the needed tools, the spare wheel and have him climb on the back of a pickup truck. What follows will look like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/R9yyf.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/R9yyf.png&quot; alt=&quot;Stuck landing gear on a PA-28 being freed from the ground&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stuck landing gear on a PA-28 being freed from the ground (picture &lt;a href=&quot;https://www.youtube.com/watch?v=lUlV-8MXm4k&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This repair needed only a jerk on the gear to get it unstuck. Changing a wheel takes much longer and is practically impossible this way.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-22T17:01:46.840" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25489" PostTypeId="2" ParentId="25484" CreationDate="2016-02-22T18:06:48.727" Score="2" Body="&lt;p&gt;You compare different things. Me can use your example. Wing sinks 1 foot minute and goes forward 10 foot. Another sinks 2 foot minute and goes forward 30 foot. You start with 10 foot. 10x10=100 and 5x30=150. You can see that second wing though sinking at 2 foot per minute was going faster and moved 150ft instead of 100ft. So the angle is shallower. &#xA;The same is in real live. If you look at the glider manual it will have two speeds. Max Glide speed and Min Sink(endurance speed, always lower). &lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-02-22T18:06:48.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25491" PostTypeId="2" ParentId="25486" CreationDate="2016-02-22T18:16:57.913" Score="6" Body="&lt;p&gt;Accessing hydraulic lines &amp;amp; resevoirs is perfectly straightforward in plenty of aircraft -- the C-130 as one example.  With crew chiefs &amp;amp; their tools &amp;amp; spare parts on board, a temp repair on a hydraulic line would be possible. Highly unusual, but possible. Spare fluid is common enough to have on-board to replenish the resevoirs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, access to the tires... Nope.  I can't think of anything where you could do that, and it would have to be a designed-in capability. Typically, crew-accessible areas are pressurized, but where the wheels retract, aren't.  You have things like access to unpressurized bomb bays, and in unpressurized aircraft that's not a barrier, but still... If there are designs where the crew can access the tires in flight, I'm not picturing them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted elsewhere, landing with a flat tire isn't typically a big deal.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-02-22T18:16:57.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25492" PostTypeId="2" ParentId="164" CreationDate="2016-02-22T18:20:39.577" Score="0" Body="&lt;p&gt;Autopilot theoretically could not care about the trim but if you disconnected it and plane was out of trim in could depart flight path rapidly.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-02-22T18:20:39.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25493" PostTypeId="1" AcceptedAnswerId="25498" CreationDate="2016-02-22T18:30:40.147" Score="10" ViewCount="3344" Body="&lt;p&gt;Are ground &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_marshalling&quot; rel=&quot;nofollow noreferrer&quot;&gt;marshalling&lt;/a&gt; operations still conducted by personnel on the ground? Are there any airports that still do this procedure?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0VGi2.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0VGi2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://commons.m.wikimedia.org/wiki/Category:Marshallers#/media/File%3AA_Polish_airman_marshals_a_U.S._Air_Force_C-130J_Super_Hercules_aircraft_March_13%2C_2014%2C_at_Lask_Air_Base%2C_Poland_140313-F-BH566-088.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="1696" LastEditDate="2018-04-11T14:34:31.493" LastActivityDate="2018-04-11T14:34:31.493" Title="Are aircraft still guided by ground marshals?" Tags="&lt;airport&gt;&lt;ground-operations&gt;&lt;aircraft-operations&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25494" PostTypeId="2" ParentId="25493" CreationDate="2016-02-22T18:32:52.207" Score="3" Body="&lt;p&gt;For what I know, the EAA AirVenture still uses this method. I have heard from a few friends in the Civil Air Patrol about this.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-02-22T18:32:52.207" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25496" PostTypeId="2" ParentId="25484" CreationDate="2016-02-22T18:49:21.343" Score="18" Body="&lt;p&gt;Glide ratio is the ratio of the distance a glider can travel horizontally to the altitude lost in transit. For instance, if a glider can travel 40 miles horizontally while losing one mile of altitude, the glide ratio is 40:1 (typical for a medium-high performance glider). The &lt;em&gt;best glide ratio&lt;/em&gt; or &lt;em&gt;maximum glide ratio&lt;/em&gt; is simply the best ratio a glider can achieve. Best glide ratio is achieved at a specific airspeed, which varies depending on the glider type. One flies at best glide speed in order to maximize the distance covered. When gliders are flying in a straight line and want to go as far as possible, they fly at best glide speed (typically 55-65kts).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Minimum sink is the minimum vertical speed the glider is capable of flying at in still air (typically 100-200ft/min). Minimum sink is also achieved at a specific airspeed, depending on the glider type (typically 40-50kts). One flies at minimum sink speed to maximize altitude gain when flying in lift. If you're circling in a thermal that is going up at 500ft/min, and your minimum sink speed is 100ft/min, then the glider will go up at 400ft/min.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To review, the key differences are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Glide ratio specifies how &quot;flat&quot; the glide angle is&#xA;&lt;li&gt;Minimum sink specifies the minimum vertical speed the glider can fly at&#xA;&lt;li&gt;One flies at best glide speed to maximize the distance covered vs altitude lost&#xA;&lt;li&gt;One flies at minimum sink speed to maximize altitude gain in lift&#xA;&lt;li&gt;Best glide ratio is achieved at a higher airspeed than minimum sink&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Any aircraft can be a glider with its engines out, so this applies to all aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, I don't understand how the lowest sink rate you can get isn't the same as the shallowest angle you can glide at.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Remember that minimum sink comes at a lower airspeed than best glide. At minimum sink speed, the glide ratio is worse because even though the aircraft is sinking slower, it is also moving forward slower. &lt;/p&gt;&#xA;" OwnerUserId="9195" LastEditorUserId="9195" LastEditDate="2016-02-22T18:56:31.290" LastActivityDate="2016-02-22T18:56:31.290" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25497" PostTypeId="2" ParentId="25465" CreationDate="2016-02-22T19:25:19.583" Score="6" Body="&lt;p&gt;One interesting case of actually wet thrust, as opposed to afterburners, is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot; rel=&quot;noreferrer&quot;&gt;Harrier Jump Jet&lt;/a&gt;, which can &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Pegasus#Water_Injection&quot; rel=&quot;noreferrer&quot;&gt;inject water&lt;/a&gt; into its engines for up to 90 seconds to increase performance for vertical takeoff and landing without melting its turbine blades. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Water_injection_(engine)#Use_in_aircraft&quot; rel=&quot;noreferrer&quot;&gt;use of water in jet engines&lt;/a&gt; is interesting because it not only cools the turbine, but simultaneously adds thrust through the added mass and steam expansion.&lt;/p&gt;&#xA;" OwnerUserId="13656" LastActivityDate="2016-02-22T19:25:19.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25498" PostTypeId="2" ParentId="25493" CreationDate="2016-02-22T19:29:24.497" Score="9" Body="&lt;p&gt;Typically, marshalling is used to guide aircraft to their parking stand. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are alternatives available (&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Stand_guidance_system&quot;&gt;Visual Guidance Docking Systems&lt;/a&gt;) that allow pilots to park their aircraft at the right spot without the aid of a marshaller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In its simplest form, the parking spot has a big identifier to allow the pilot to select the right stand, a centreline for the nose wheel to follow, a marking where the nosewheel should stop and a mirror so the pilot can see where the nose wheel is relative to the marking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In its more advanced form, there are pressure plates in the stand that determine the position of the aircraft, a laser scanning system that determines the exact position of the aircraft and whether the stand is obstacle free, and a digital display guiding the pilot during parking. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case the VDGS is not available or cannot handle the specific aircraft type, a marshaller will have to step in.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="595" LastEditDate="2016-02-22T20:04:25.903" LastActivityDate="2016-02-22T20:04:25.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25500" PostTypeId="1" AcceptedAnswerId="25519" CreationDate="2016-02-22T20:04:59.477" Score="3" ViewCount="192" Body="&lt;p&gt;In a form off a kite can wind be redirected like a sail boat in any direction? Can cross winds around a jet stream be helpful in speed in such a design?&lt;/p&gt;&#xA;" OwnerDisplayName="user20435" LastEditorUserId="167" LastEditDate="2016-02-23T01:47:08.840" LastActivityDate="2016-02-23T07:44:38.173" Title="Can a kite take advantage of crosswinds to gain speed?" Tags="&lt;aerodynamics&gt;&lt;crosswind&gt;&lt;experimental-aircraft&gt;&lt;ultralight&gt;&lt;sailplane&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ClosedDate="2016-02-23T08:25:01.073" ContentLicense="CC BY-SA 3.0" />
  <row Id="25501" PostTypeId="1" AcceptedAnswerId="25502" CreationDate="2016-02-22T20:23:39.670" Score="6" ViewCount="1090" Body="&lt;p&gt;In the animation movie &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Planes:_Fire_%26_Rescue&quot; rel=&quot;nofollow&quot;&gt;Planes 2&lt;/a&gt;&quot; we see the helicopter (Blade character) performing first a 180° roll (getting inverted chassis up and rotor down) and then the U-shaped half loop down into the normal orientation. From Wikipedia it looks like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Split_S&quot; rel=&quot;nofollow&quot;&gt;Split-S&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are helicopters actually capable of doing this? The concerns are&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;An inverted wing still may provide a lift upwards, but the inverted rotor will pull downward. Hence the inverted orientation seems risky.&lt;/li&gt;&#xA;&lt;li&gt;Wings provide air support while making the sharp U-turn. Can the helicopter rotor do the same?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If a helicopter would manage this figure, would it trade altitude to speed as the fixed wing planes do? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the model is important, the helicopter looks somewhat like &lt;a href=&quot;https://en.wikipedia.org/wiki/AgustaWestland_AW139&quot; rel=&quot;nofollow&quot;&gt;Augusta Westland&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="595" LastEditDate="2016-02-23T07:19:01.337" LastActivityDate="2016-02-23T18:47:07.200" Title="Can helicopters perform the Split S maneuver?" Tags="&lt;helicopter&gt;&lt;aerobatics&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25502" PostTypeId="2" ParentId="25501" CreationDate="2016-02-22T20:45:05.613" Score="13" Body="&lt;p&gt;Yes, but you need &lt;a href=&quot;https://en.wikipedia.org/wiki/Helicopter_rotor#Rigid&quot;&gt;a rigid head&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A rigid head does not have any hinges, instead, the blades flex up and down.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wings don't know or care if they are upside down or right way up, indeed, &lt;a href=&quot;http://www.copters.com/aero/airfoils.html&quot;&gt;most helicopter blades are symmetrical&lt;/a&gt;.  It only cares how much airflow there is and at what angle it hits it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's an &lt;a href=&quot;https://www.youtube.com/watch?v=ZgGKtX2FJ18&quot;&gt;EC-120 performing a split S&lt;/a&gt; and a &lt;a href=&quot;https://www.youtube.com/watch?v=NGIViuBf6Ac&quot;&gt;Lynx showing what's possible.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps the best around is &lt;a href=&quot;https://www.youtube.com/watch?v=uYbx5H5e9Es&quot;&gt;Chuck Aaron, displaying for Red Bull.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here, Dennis Kenyon shows &lt;a href=&quot;https://www.youtube.com/watch?v=iJ9qwAu8dCM&quot;&gt;about as good as it can get with a semi-rigid head.&lt;/a&gt;  He gets close to inverted but never actually flips over.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-02-23T18:47:07.200" LastActivityDate="2016-02-23T18:47:07.200" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25503" PostTypeId="1" CreationDate="2016-02-22T20:48:41.110" Score="5" ViewCount="535" Body="&lt;p&gt;When passenger jets have a runway excursion incident &lt;a href=&quot;http://news.sky.com/story/1646006/passenger-jet-veers-off-runway-in-birmingham&quot; rel=&quot;noreferrer&quot;&gt;such as this one in Birmingham&lt;/a&gt; it is apparently common practice to send emergency services vehicles to the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8VBoA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8VBoA.jpg&quot; alt=&quot;Birmingham accident A320&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are emergency services vehicles necessary?&lt;br&gt;&#xA;I would think the plane is more than capable of getting back onto the Tarmac, so why doesn't it?&lt;/p&gt;&#xA;" OwnerUserId="13555" LastEditorUserId="22726" LastEditDate="2019-02-22T04:28:53.740" LastActivityDate="2019-02-22T04:28:53.740" Title="Why are emergency vehicles needed for a runway excursion?" Tags="&lt;commercial-aviation&gt;&lt;accidents&gt;&lt;runway-overrun&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25504" PostTypeId="2" ParentId="25503" CreationDate="2016-02-22T21:22:38.960" Score="5" Body="&lt;p&gt;Going off the the runway can be pretty rough. It not unlikely that a passenger got injured or part of the plane got damaged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Going full throttle on the jets will rip up the dirt and grass and fling it everywhere. It will also put quite a bit of force onto the landing gear which already got a beating from going into the grass. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much safer to tow it back. You can see the white towing vehicle in front of the plane. &lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2016-02-22T21:22:38.960" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25505" PostTypeId="2" ParentId="25503" CreationDate="2016-02-22T21:29:34.927" Score="13" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why are emergency service vehicles necessary?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Something might have been damaged. What if something was and there is a fuel leak somewhere? Hydraulic leaks are also dangerous, and more likely as hydraulic lines run to the brakes and nose wheel steering. Better safe than sorry, so emergency services go check.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes, they also disembark passengers via the ladder if it looks like towing the aircraft to terminal will take too long and the aircraft is on unpaved surface where the mobile stairs have trouble going.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can also help with moving the plane, especially on smaller airports that only have one runway and so have to close until the plane is moved away anyway.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I would think the plane is more than capable of getting back onto the Tarmac, so why doesn't it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, it isn't. Aircraft not designed for unpaved surface will usually sink in somewhat, especially if the ground is wet, and require a lot of power to pull out. Sometimes, the tow truck is enough to get it out, sometimes they have to put planks under the wheels and sometimes they have to get out hydraulic jacks or inflatable support bags.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the plane did not dig in and is easy to move, providing the power with the engines is not a smart thing to do, because the engines will throw up dirt and stones that could damage them, other parts of the aircraft, or something else around. Tow truck is much better for that job.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-02-25T05:41:31.537" LastActivityDate="2016-02-25T05:41:31.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25506" PostTypeId="1" AcceptedAnswerId="25508" CreationDate="2016-02-22T22:02:37.087" Score="7" ViewCount="2143" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/25491/11953&quot;&gt;this answer&lt;/a&gt;, Ralph wrote:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Spare fluid is common enough to have on-board to replenish the resevoirs.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;After reading that, I recalled an incident I was told about nearly twenty years ago about a hydraulic failure on an Aeroflot flight, where Lemonade (a Russian soft drink of sorts) was used in a pinch. I've always wondered about the authenticity of this story.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it true? Is it plausible? Have there been other times where some non-ideal fluid was used in place of hydraulic fluid?&lt;/p&gt;&#xA;" OwnerUserId="11953" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-02-23T01:37:52.747" Title="Is is possible to use non-hydraulic fluids in a hydraulic system in an emergency?" Tags="&lt;emergency&gt;&lt;hydraulic-system&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25507" PostTypeId="2" ParentId="25506" CreationDate="2016-02-22T22:10:03.383" Score="6" Body="&lt;p&gt;&lt;strong&gt;In short, yes!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing is, a fluid is fluid. Any fluid that is similar to water or oil can be used. But, you would need to be on the ground and have enough of that fluid. Also, using such a fluid will introduce potential damage and corrosion to the system, so a flush should be done as soon as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, there might be hydraulic systems that experience higher temperatures, like brakes - in that case, regular water would be a bad idea or anything water based.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lemonade is a a carbonated drink, and using carbonated drink as a hydraulic fluid is a bad as it would emit a lot of gas, and has significantly lower boiling point. So I would speculate that if they did use it, they probably let it vent out all the CO2 first.&lt;/p&gt;&#xA;" OwnerUserId="9146" LastActivityDate="2016-02-22T22:10:03.383" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25508" PostTypeId="2" ParentId="25506" CreationDate="2016-02-22T22:23:39.017" Score="16" Body="&lt;p&gt;Is it possible? Sure. Theoretically. &lt;em&gt;Once.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't speak to your Aeroflot scenario without more details, but broadly speaking &lt;em&gt;any&lt;/em&gt; liquid will work as &quot;hydraulic fluid&quot; within certain limits: At the most basic level all that is required is that it be incompressible and flow at an acceptable rate (i.e. It is a liquid with a viscosity that falls within a certain range).  Engine oil is frequently used as a hydraulic fluid for certain applications (constant-speed propellers on small aircraft), and special-purpose hydraulic oil for others (the brakes on small aircraft).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;There are some challenges to using any old liquid as &quot;hydraulic fluid&quot; though, which are why I say this is only theoretically possible (and probably only once). The two big concerns are the fluid's operating temperature range - its freezing and boiling points - and its corrosion potential.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's consider MIL-PRF-5606H (a typical hydraulic oil) and ordinary lemonade as examples:  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Operating Temperature Range&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;In terms of temperature 5606 hydraulic oil has a much wider operating range than lemonade: It's &quot;pour point&quot; is below -60°C and its boiling point over 175°C, while lemonade's operating temperature range is probably close to water: It will freeze somewhere close to 0°C and boil somewhere close to 100°C (the exact numbers will depend on the chemical composition of the lemonade).&lt;br&gt;&#xA;If we use both of these fluids in a brake system there is a chance the lemonade will boil when the brakes are applied (creating a gas pocket that's compressible, and reducing brake effectiveness), or that it will freeze in flight and the brakes will fail to apply because the ice is blocking the lines. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Corrosion Potential&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As far as corrosion potential 5606 hydraulic oil is a mineral oil with some red dye in it: Since it doesn't contain dissolved water or electrolytes it's generally non-corrosive. Lemonade on the other hand is nothing &lt;em&gt;but&lt;/em&gt; water and dissolved electrolytes (mainly citric acid to make it taste like lemon) plus sugar and a few other things. If we ran hydraulic actuators on this stuff we should expect them to corrode (rust) and eventually fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's possible that under the right circumstances an airplane could complete a flight with lemonade, water, etc. as &quot;hydraulic fluid&quot;, but having done so the maintenance department will have to purge the &quot;creative&quot; fluid from the system, and probably follow some steps to remove any corrosive residue from the system (possibly up to and including replacing major system components). Long term operation in such a condition would probably damage components to the point where many of the system's moving parts (actuators, valves, etc.) would need to be replaced.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-02-22T22:23:39.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25509" PostTypeId="2" ParentId="7972" CreationDate="2016-02-22T22:33:09.897" Score="3" Body="&lt;p&gt;They clearly can't have meant 45 thousand tonnes. Even the likes of the AN225 and the A380 are nowhere near that big. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In parts of continental europe they use the comma as a decimal seperator. All too often I see datasheets (I work in electronics) where the text is in english but the numbers are using european format. However the fact that there seems little reason to use three decimal places for a number like that and the fact they use , as a thousands seperator in the fuel section makes me think this probablly wasn't the source for the original error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect whoever wrote it somehow mixed up kilograms and tonnes and this may have been compounded on proofreading by the above issue of some countries using decimal commas.&lt;/p&gt;&#xA;" OwnerUserId="11774" LastActivityDate="2016-02-22T22:33:09.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25510" PostTypeId="2" ParentId="25447" CreationDate="2016-02-22T23:11:42.103" Score="5" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/JO_7210.3Y.pdf&quot; rel=&quot;noreferrer&quot;&gt;JO 7210.3Y&lt;/a&gt;, &lt;em&gt;Air Traffic Organisation Policy&lt;/em&gt;, section 4-4-2 there are several requirements from both the FAA and FCC. The FAA requirements are (paraphrased from the JO):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Comply with FCC regulations (remember that the FCC is responsible for radio communication technical regulations, not the FAA)&lt;/li&gt;&#xA;&lt;li&gt;Get FAA approval &quot;to avoid possible duplication or conflict&#xA;with air−ground call signs assigned on a national&#xA;basis to other aircraft operators&quot;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The FCC requirements are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;rgn=div5;view=text;node=47%3A5.0.1.1.2;idno=47;cc=ecfr#se47.5.87_1107&quot; rel=&quot;noreferrer&quot;&gt;47 CFR 87.107&lt;/a&gt; (not 87.115 as the JO says):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) &lt;em&gt;Aircraft station&lt;/em&gt;. Identify by one of the following means:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Aircraft radio station call sign.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The type of aircraft followed by the characters of the&#xA;  registration marking (“N” number) of the aircraft, omitting the prefix&#xA;  letter “N.” When communication is initiated by a ground station, an&#xA;  aircraft station may use the type of aircraft followed by the last&#xA;  three characters of the registration marking. Notwithstanding any&#xA;  other provision of this section, an aircraft being moved by&#xA;  maintenance personnel from one location in an airport to another&#xA;  location in that airport may be identified by a station identification&#xA;  consisting of the name of the company owning or operating the&#xA;  aircraft, followed by the word “Maintenance” and additional&#xA;  alphanumeric characters of the licensee's choosing.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) The FAA assigned radiotelephony designator of the aircraft&#xA;  operating organization followed by the flight identification number.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) An aircraft identification approved by the FAA for use by aircraft&#xA;  stations participating in an organized flying activity of short&#xA;  duration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In other words, your call sign must be approved in advance by the FAA, otherwise you can't legally use it per FCC regulations. In reality, if you call up ATC as &lt;em&gt;Little Piggy 27&lt;/em&gt; you'll either get a laugh and a &quot;no, seriously?&quot; or - in the worst case - you'll just annoy them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also military call signs in use but I know nothing about them. I do remember being in the pattern while an Air National Guard aircraft out of Memphis, TN was doing touch and goes using the call sign Elvis 1. But I have no idea how that call sign was set up between the ANG and FAA.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-02-22T23:11:42.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25511" PostTypeId="2" ParentId="25447" CreationDate="2016-02-22T23:45:33.450" Score="0" Body="&lt;p&gt;From ATC's point of view...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot calls up as &quot;little piggy 27&quot;, the controller &lt;strong&gt;may&lt;/strong&gt; respond &lt;strong&gt;initially&lt;/strong&gt; with &quot;little piggy 27&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When &lt;strong&gt;ATC establishes&lt;/strong&gt; communication with a GA aircraft, they state the prefix &quot;November&quot; followed by the phonetic numbers/letters of the aircraft registration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, you could replace &quot;November&quot; with aircraft type, the model, or the manufacturer’s name, and ATC can respond in kind going forward.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[Info from &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;JO 7110.65&lt;/a&gt;, 2−4−20. AIRCRAFT IDENTIFICATION]&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2016-02-22T23:45:33.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25512" PostTypeId="1" AcceptedAnswerId="25652" CreationDate="2016-02-22T23:55:28.763" Score="5" ViewCount="816" Body="&lt;p&gt;How do the different types of slotted flaps (Single, double, and triple as well as a non-slotted one just for comparison) differ aerodynamically? I read in Joe Sutter's book &lt;em&gt;747&lt;/em&gt; that a double-slotted flap design for the 747 had 8 knots higher speed than a triple-slotted one. How does that work?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-02-27T16:02:35.763" Title="What are the aerodynamic differences between the different types of slotted flaps?" Tags="&lt;flaps&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25513" PostTypeId="2" ParentId="25473" CreationDate="2016-02-23T01:31:44.980" Score="2" Body="&lt;p&gt;For conventional VORs, Positive sensing occurs when the headng currently being flown is on the top half of the VOR.  Reverse sensing occurs when the current heading is on the bottom half of the VOR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://allaboutairplanes.files.wordpress.com/2011/06/vor-sensing.png&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://allaboutairplanes.files.wordpress.com/2011/06/vor-sensing.png&quot; alt=&quot;Picture of conventional VOR with positive / reverse sensing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Used wth permission from &lt;a href=&quot;https://allaboutairplanes.wordpress.com&quot; rel=&quot;nofollow&quot;&gt;allaboutairplanes.wordpress.com&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking this theory to the HSI where the currently flown heading is always on the top half and you can never have reverse sensing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also proper technique to set in the front course when flying a LOC/BC approach.  This will negate the effects of reverse sensing for HSIs.  To get all my students into the habit of setting in the front course for HSIs I teach to always set in the front course even when flying on conventional instruments.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I don't believe in positive and reverse sensing anymore.  A discussion for another day.&lt;br&gt;&#xA;&lt;a href=&quot;https://allaboutairplanes.wordpress.com/2011/06/16/tracking-and-intercepting-vors/&quot; rel=&quot;nofollow&quot;&gt;Tracking and intercepting VORs&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="12720" LastEditDate="2016-02-29T14:34:54.313" LastActivityDate="2016-02-29T14:34:54.313" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25514" PostTypeId="2" ParentId="25506" CreationDate="2016-02-23T01:37:52.747" Score="4" Body="&lt;p&gt;In LR-JET type airplanes Learjet uses an emergency air bottle in the event hydraulic fluid is lost.  The emergency air is pressurized between 1800 and 3000.  When the bottle is opened to extend the gear or apply pressure to the brakes, the air will move shuttle valves causing air pressure to extend the gear or stop the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know it is not the same as replenishing it with some soft drink but it does answer the question of whether or not something like this is possible.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-23T01:37:52.747" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25515" PostTypeId="2" ParentId="8428" CreationDate="2016-02-23T02:19:22.197" Score="0" Body="&lt;p&gt;In airplanes without hydraulic actuators on the primary flight surfaces an autopilot usually consists of servos and a computer.  The servos lock onto the cables that control the primary flight surfaces.  When the autopilot moves the cable you can visibly see the control yoke move the proper amount.  It is not fast and will not cause damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The computer is monitoring the pitot/static instruments through the associated air data computer and the gyroscopic instruments through the associated attitude/heading reference system. Through algorithms, the autopilot computer controls the airplane.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-02-23T02:19:22.197" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25516" PostTypeId="1" CreationDate="2016-02-23T03:51:14.260" Score="12" ViewCount="1987" Body="&lt;p&gt;This is a safety question about fuel and fires. This all regards commercial aviation for large passenger planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most fuel is stored in the wings, but in the largest planes, there's also a center tank for the longest flights. &lt;strong&gt;It's this center tank I'm concerned with.&lt;/strong&gt; In the event of a fire, this seems to be the most dangerous tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm obviously concerned with fires in the fuselage, or very close to it. Obviously this is where all the people are and we don't want smoke or flame there, but remember also there are &lt;strong&gt;overhead oxygen canisters&lt;/strong&gt; that if heated or fueled, will explode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet fuel is flammable by its nature. This cannot be changed because its purpose is to combust in an internal combustion engine. So it seems the best we can do is to keep the fuel as far from the fuselage as possible, to make it unlikely that fuel will cause a fire there (initially).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Isn't there someplace we can move this center tank? Some ideas I thought of: store fuel in anti-shock bodies on the wings (or they could be just small sears-haack bodies on the wings); store fuel in the empannage; store fuel in nacelles that have a larger diameter than the engine itself, to make room for fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another exotic idea: Is it possible to engineer the wing such that the most likely structural failure will happen first near the wingtip rather than the wingroot? This would spill the fuel farther from the fuselage. (I got this idea from a really wierd Boeing 747 crash in Netherlands where one engine jumped off then fell back into the other engine, causing 2 engine losses. They said some pins were designed to fail first for a more &quot;benign&quot; failure, but apparently those pylon pins were engineered wrong.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's one more tricky caveat, though: &lt;strong&gt;the cross feed line&lt;/strong&gt; to balance fuel loads in the wings. If we eliminate this line, we increase the dangerous consequences of a fuel imbalance. But, it's interesting to think of what might cause a major fuel imbalance other than a leak, in which case the cross feed valve should &lt;strong&gt;not&lt;/strong&gt; be opened. I can't think of anything so I'm leaning toward the opinion that this line can be eliminated too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; Thanks to bodargpd for pointing this out. Losing an engine in flight means the consumption rates will be hugely different. Without a cross-feed line, all that fuel in the other wing is unavailable and we may have to ditch early. So the cross-feed line is still necessary. I still say this is much less dangerous than a center fuel tank, however. It would also be nice if we engineered the cross-feed line to be weakest at the sides, so any leak will most likely be as far to the outside of the fuselage as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To sum up, the basic question is, can we viably move the center tank volume of fuel somewhere outside the fuselage?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; I'm &lt;strong&gt;not&lt;/strong&gt; primarily worried about fuel explosions. I'm concerned mostly about fuel leaks during hard emergency landings. I'd rather have a fuel leak out on the wing than in the fuselage.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-24T00:40:10.077" LastActivityDate="2019-08-10T15:30:57.537" Title="Can we eliminate the center tank of large passenger planes?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;fuel-tanks&gt;&lt;fire&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25517" PostTypeId="2" ParentId="25516" CreationDate="2016-02-23T04:31:27.583" Score="15" Body="&lt;p&gt;I'm assuming you're talking passenger safety in the event of a ground impact - if anything happened midair, it wouldn't really matter if it were in the fuselage or one of the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving the fuel somewhere else is going to have center of gravity implications. Moving it to wing pods or lager nacelles in particular would increase drag, which would require the plane to have even more fuel on board, which seems counterproductive to decreasing the fuel risk to passengers (and, of course, would substantially increase the cost of operating the flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some military aircraft &lt;em&gt;do&lt;/em&gt; carry fuel in removable underwing fuel pods (particularly fighters being ferried somewhere, where increased endurance/time between refuelings is more important than performance for that particular mission). However, that's less a safety design and more the lack of anywhere else to put the extra fuel on a small aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine fails, the rate of fuel consumption is going to be different on each side of the plane. Although both are rare, you likely have far more situations where different wings use fuel at different rates than situations where having fuel feed under the body would be dangerous. If that's true, then removing the cross-feed line would be &lt;em&gt;more&lt;/em&gt; dangerous than leaving it in.&lt;/p&gt;&#xA;" OwnerUserId="1024" LastActivityDate="2016-02-23T04:31:27.583" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25519" PostTypeId="2" ParentId="25500" CreationDate="2016-02-23T07:44:38.173" Score="4" Body="&lt;p&gt;Why do you need a kite? A glider is much better suited to the task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, nature has invented this long ago. Albatrosses use a technique called &lt;a href=&quot;https://en.wikipedia.org/wiki/Dynamic_soaring&quot; rel=&quot;noreferrer&quot;&gt;dynamic soaring&lt;/a&gt; to cover wide distances over water, using the windshear close to the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ingo_Renner&quot; rel=&quot;noreferrer&quot;&gt;Humans&lt;/a&gt; have tried to imitate this with gliders, albeit with limited success. The few who tried it could indeed stay in the air by harvesting energy from windshear, but the dynamic loads (up to 4 g) were too much to do this over an extended time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-23T07:44:38.173" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25521" PostTypeId="2" ParentId="25415" CreationDate="2016-02-23T09:52:26.593" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;difference between nominal and fault file&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is found inside the &lt;code&gt;.tar.gz&lt;/code&gt; file. From the &lt;code&gt;README&lt;/code&gt; file contained in the page you linked:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;the &lt;strong&gt;Simulation_Info.txt&lt;/strong&gt; contains a summary of the number of flights,&#xA;  the fault type that was simulated, if it is nominal or not, and if not&#xA;  what flight and time sample the fault was introduced.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;There are 27 parameteres used, among these which parameters will affect fan, HPC, HPT, LPC, LPT&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I assume you are asking what are those 27 parameters.&#xA;From the &lt;code&gt;README&lt;/code&gt; file that is found in the page you linked:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/e7x56.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e7x56.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;what is the threshold value for these parameters or when do we say that the parameter has reached its max value and above which it would lead to fault condition.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A detailed answer is out of scope for this site, it heavily depends on the failure simulated. The documentation of the various tests should have enough details to understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, hard absolute values are definitely of no use here, different engines will have different characteristics: the numbers valid for the engine simulated here will be applicable to basically no real engine.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-02-23T09:57:47.607" LastActivityDate="2016-02-23T09:57:47.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25524" PostTypeId="1" CreationDate="2016-02-23T14:24:40.617" Score="9" ViewCount="8113" Body="&lt;p&gt;The pressurization in the cabin requires the doors have their seals working properly. How do they prevent pressurized air from leaking from the doors?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="62" LastEditDate="2016-02-23T15:35:27.783" LastActivityDate="2016-02-23T22:32:27.990" Title="How do door seals work?" Tags="&lt;cabin-pressure&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25525" PostTypeId="2" ParentId="25524" CreationDate="2016-02-23T14:36:13.787" Score="22" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How do they prevent pressurized air to leak from the doors?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They don't. The seal does not have to be perfectly airtight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The requirement is that it will create enough impediment to the air that wants to gush out, where &quot;enough&quot; is defined by the capability of the conditioning system to input new air into the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, everything is fine as long as the air mass that gets out of the doors is less than the maximum air flow that the air conditioning system can input into the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that, as stated on &lt;a href=&quot;https://en.wikipedia.org/wiki/Environmental_control_system_%28aircraft%29#Pressurization&quot;&gt;Wikipedia&lt;/a&gt;, aircraft are equipped with one (or more) &quot;out-flow valve(s)&quot; and &quot;pressure relief valves&quot;: these valves intentionally let air out of the cabin to avoid over pressure in the cabin and thus they prevent possibly dangerous scenarios.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2016-02-23T20:47:43.543" LastActivityDate="2016-02-23T20:47:43.543" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25526" PostTypeId="1" CreationDate="2016-02-23T15:43:22.703" Score="0" ViewCount="69" Body="&lt;p&gt;I understand that there are other costs that go into the full price per seat, like maintenance, crew ect., but all I am asking about here is fuel.&lt;/p&gt;&#xA;" OwnerUserId="13552" LastActivityDate="2016-02-23T15:43:22.703" Title="What's the profit margin for airlines between fuel cost per seat price per seat to the customer?" Tags="&lt;fuel&gt;&lt;cost&gt;&lt;airlines&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-02-23T16:50:50.000" ContentLicense="CC BY-SA 3.0" />
  <row Id="25527" PostTypeId="2" ParentId="25524" CreationDate="2016-02-23T15:57:50.640" Score="10" Body="&lt;p&gt;Like any pressure seal they are generally rubber seals. You can find one of &lt;a href=&quot;http://www.google.com/patents/US2665459&quot; rel=&quot;nofollow&quot;&gt;Boeings patents here&lt;/a&gt; which covers door seals. Some smaller planes (and unpressurized GA planes) use inflatable seals, the door is closed and then the rubber boot is inflated to form a tighter seal. You can find an &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/166041&quot; rel=&quot;nofollow&quot;&gt;interesting discussion on the seals here&lt;/a&gt; but in general they may have tiny leak issues. This was &lt;a href=&quot;http://avherald.com/h?article=46e1dcdb&quot; rel=&quot;nofollow&quot;&gt;the cause of at least one A380 diversion recently&lt;/a&gt;, but it looks like airbus is working through it and has a solution. Since the cabin has an outflow valve to keep it properly pressurized a tiny leak in the door will be compensated by the outflow valve. &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-CAB_OPS-SEQ09.pdf&quot; rel=&quot;nofollow&quot;&gt;This airbus briefing&lt;/a&gt; warns that they can be hazardous and hard to detect if one does occur the crew may not know until the O2 masks deploy. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Slow/Insidious decompression involves a very gradual decrease in cabin&#xA;  pressure. Slow decompression may be the result of a &lt;strong&gt;faulty door seal&lt;/strong&gt;,&#xA;  a malfunction in the pressurization system, or a cracked window. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Slow&#xA;  decompression may not always be obvious. The cabin crew may not notice&#xA;  the changes in the cabin, until the oxygen masks drop down from the&#xA;  Passenger Service Units (PSUs).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It has been noted that leaky seals on both pressurized and unpressurized doors can lead to a very loud noise in the cabin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The seals do at least to some level try to keep water out. This is mainly because excess water may build up and then freeze as the airplane climbs. This ice build up in the door could in theory cause an issue (although I cant find any cases where it has).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-02-23T18:37:23.827" LastActivityDate="2016-02-23T18:37:23.827" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25528" PostTypeId="2" ParentId="25524" CreationDate="2016-02-23T16:07:53.413" Score="8" Body="&lt;p&gt;A lot of aircraft with pressurised cabins have plug type doors which press against the fuselage when in closed position. There is a (silicone) rubber seal where it touches against the fuselage, which minimizes air leak. The image below shows the seal in an aircraft door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vqSJl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vqSJl.jpg&quot; alt=&quot;aircraft door seal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://aviationtroubleshooting.blogspot.in/2013/02/aircraft-emergency-hatches-or-cabin.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;aviationtroubleshooting.blogspot.in&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3503" LastEditDate="2016-02-23T22:32:27.990" LastActivityDate="2016-02-23T22:32:27.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25529" PostTypeId="1" CreationDate="2016-02-23T16:33:04.377" Score="12" ViewCount="8252" Body="&lt;p&gt;Dihedral wings seems to be very common (almost if not all low-wing airliners, many modern gliders,...). Polyhedral seems to be less common and mainly found in relatively old aircraft (F4 Phatom, F4U Corsair, DR400,...). By polyhedral, I mean at least 2 dihedral angle with a sharp discontinuity between both. I don't include wings whose diheadral angle varies smoothly along the wingspan (such as this &lt;a href=&quot;http://www.airliners.net/photo/Thomson-Airways/Boeing-787-8-Dreamliner/2393773/&amp;amp;sid=71a43497a608424635d97138da3105c1&quot;&gt;B787&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I was surprised to discover that this design (polyhedral with sharp angle between the distinct diheadral sections of the wing) was elected in at least 2 project whose first flight was in the last 10 years (namely the &lt;a href=&quot;http://www.airliners.net/photo/Solar-Impulse-Project/1947739/&amp;amp;sid=892d009dfd8fcaf1b933ceb42857a749&quot;&gt;solar impulse&lt;/a&gt; and the &lt;a href=&quot;https://duckduckgo.com/?q=airbus+qinetiq+zephyr&amp;amp;t=ffab&amp;amp;iax=1&amp;amp;ia=images&quot;&gt;qinetiq zephyr&lt;/a&gt;). I do realize that both examples I gave have similar missions (stay airborne as long as possible, and thus fly slowly; gather as many sun-energy as possible, and thus fly as horizontally as possible) and may thus have similar design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given recently-designed aircraft with polyhedral wing exist, what are the pro/cons of such design over well spread dihedral wings and over the smoothly varying dihedral angle?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: note that the polyhedral does not necesseraly increase the dihedral angle as we go away from the wing root (&lt;a href=&quot;https://en.wikipedia.org/wiki/Beriev_Be-12&quot;&gt;Be 12&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/DFS_Habicht&quot;&gt;Habicht&lt;/a&gt;,...)&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2016-02-24T11:40:24.053" LastActivityDate="2019-07-19T19:00:48.437" Title="What are the pro/cons of polyhedral cranked wings?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25530" PostTypeId="2" ParentId="25529" CreationDate="2016-02-23T16:53:49.723" Score="12" Body="&lt;p&gt;While dihedral wings offer increased stability in the roll axis, they also decrease the lift that the wings provide. A polyhedral wing provides a compromise: a steep dihedral at the tip of the wing in order to maximize stability, and a shallower dihedral angle closer to the root in order to maximize lift. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/CwTGO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CwTGO.jpg&quot; alt=&quot;Poly wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, a polyhedral wing allows the best of both worlds for a wing design. Other applications of a polyhedral wing are utilitarian; the gull wing on the Vaught F4U Corsair is designed so that the landing gear is positioned close to the ground while maintaining roll stability and aerodynamics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BK0dm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BK0dm.jpg&quot; alt=&quot;Corsair landing gear&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="5517" LastEditDate="2016-02-23T17:01:10.133" LastActivityDate="2016-02-23T17:01:10.133" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25531" PostTypeId="1" CreationDate="2016-02-23T19:28:21.677" Score="4" ViewCount="172" Body="&lt;p&gt;For a homebuilt prototype aircraft meant for the primary or Canadian JAR-VLA category, is it OK to assume that spar stresses (other than landing loads) can be calculated using zero-wing-fuel numbers? Or perhaps the landing loads usually negate that zero-fuel stress relief?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, when specifying plus and minus stresses, both the wing and its fuel content can be discounted except for full-fuel aileron loads?&lt;/p&gt;&#xA;" OwnerUserId="13673" LastEditorUserId="13673" LastEditDate="2016-02-24T14:56:19.247" LastActivityDate="2018-07-28T13:35:18.253" Title="Can spar stresses be calculated using zero (wing) fuel?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25533" PostTypeId="1" AcceptedAnswerId="25535" CreationDate="2016-02-23T19:44:50.250" Score="8" ViewCount="3379" Body="&lt;p&gt;If I've done my training say 85% in a C152 and 15% in a C172, then upon my earning my PPL, what am I allowed to fly legally?  I assume the 152, but not sure about the 172. Is this indicated somehow in my logbook? When is a separate check out required for a new airplane and assuming the same type (i.e., SEL, fixed gear, fixed pitch prop, non pressurized, etc.), what would this typically entail?  Is this an FAA requirement or a liability requirement for clubs, etc.?&lt;/p&gt;&#xA;" OwnerUserId="9161" LastEditorUserId="62" LastEditDate="2016-02-24T00:20:18.380" LastActivityDate="2016-02-24T18:05:07.987" Title="For a private GA pilot, when is an endorsement needed for a particular type of aircraft?" Tags="&lt;faa-regulations&gt;&lt;liability&gt;&lt;logbook-endorsements&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25534" PostTypeId="1" AcceptedAnswerId="25536" CreationDate="2016-02-23T19:54:05.020" Score="9" ViewCount="6313" Body="&lt;p&gt;It is said that they are exposed to 50% more of radiation than on the ground and they are prone to skin cancer, so, is there any way of reducing the amount of radiation for pilots?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-23T23:55:37.310" LastActivityDate="2018-02-26T11:37:50.287" Title="How do pilots avoid radiation?" Tags="&lt;aircraft-design&gt;&lt;pilots&gt;&lt;cockpit&gt;&lt;airline-pilot&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25535" PostTypeId="2" ParentId="25533" CreationDate="2016-02-23T19:54:25.733" Score="11" Body="&lt;p&gt;There are two aspects here, one what is required legally and then what may be required locally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a legal standpoint (in your case) the basic PPL will allow you to fly single engine, fixed pitch prop, under 200HP, fixed gear aircraft. If you want to go over 200 HP you will need a High Performance check out and log book endorsement. For a constant speed prop/folding gear/movable flap (all 3 are required to require this endorsement) plane you will need a complex endorsement in your log book. You may want to fly something like a Piper Cub which will require a tail wheel endorsement. If you are lucky enough (and have the funding to do so) you may find your self in a small pressurized single (or twin) like the &lt;a href=&quot;http://www.piper.com/aircraft/m-class/m500/&quot; rel=&quot;nofollow&quot;&gt;Piper Meridian&lt;/a&gt; or &lt;a href=&quot;http://www.tbm.aero/&quot; rel=&quot;nofollow&quot;&gt;TBM 900&lt;/a&gt; these planes will require a high altitude checkout as well. &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Advanced-Flight-Training/Ratings-and-Endorsements/Other-Ratings&quot; rel=&quot;nofollow&quot;&gt;AOPA has a nice summary of the endorsements here&lt;/a&gt;. If you want the full &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/61.31&quot; rel=&quot;nofollow&quot;&gt;FAA FAR regs you can find them here&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now as for a club or school that depends on a variety of factors including their insurance and their personal limits. I'll offer some personal experience which seems to be pretty par for the course. The flight school I fly from requires a checkout in type from every new renter before you can fly it even if you have a PPL and the proper endorsements. They don't have an official amount of time but it usually takes about an hour with an instructor. The former flight school I was at had the same deal with the exception of their Saratoga which they also required an instrument rating (along with their checkout).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My buddy's flight club is somewhat similar. They require a check out in their Archer and Dakota to fly solo. They also have a &lt;a href=&quot;http://www.phillyflyingclub.com/faq/faq.htm&quot; rel=&quot;nofollow&quot;&gt;Lance which they require 25 hours time in type and a 5 hour check out in the plane&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for your log book you should be logging the full type of aircraft for every flight. For example when I fly the Warrior I make sure to note PA-28-161 and the Archer I fly is noted as PA-28-181 when I record hours this way I can note time in type at a detailed level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth with the PA-28 airframe it seems that some places to allow you to fly the lower rated planes if you are checked out in the higher power ones. The same basic frame was built in a 140, 160, 180 and 235HP variant over the years and has little differences aside from useful load and V speeds. For example at the place I go if you are checked out in the Archer first you are allowed to fly the Warrior with out a checkout.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This will also extend to ownership should that be the path you go down. In that case you insurance company may require a certain amount of hours of time in type before you are allowed to solo your plane. Keeping that in mind you are not actually prevented from buying the plane and will be insured under the stipulation that the first hours in the plane are with an instructor. When a buddy of mine (instrument rated and close to 600 hours at the time) upgraded from his 72 Archer to a 95 Saratoga HP his insurance company mandated he do 25 hours in type with an instructor before taking the plane solo. The first 25 hours he flew his plane were with an instructor (this included transporting the plane from the factory in Vero Beach to his home field). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can legally fly both planes once you have your PPL. What someone will let you fly should be pretty well addressed above. Neither the 172 or 152 requires a specific type rating like larger planes do.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-02-24T18:05:07.987" LastActivityDate="2016-02-24T18:05:07.987" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25536" PostTypeId="2" ParentId="25534" CreationDate="2016-02-23T20:29:08.530" Score="14" Body="&lt;p&gt;Broadly speaking, radiation exposure can be mitigated in three ways: &lt;strong&gt;Time&lt;/strong&gt;, &lt;strong&gt;Distance&lt;/strong&gt;, and &lt;strong&gt;Shielding&lt;/strong&gt;.  Two of these mitigating factors can't really be improved: Distance and Time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For &lt;strong&gt;distance&lt;/strong&gt;, the radiation exposure concern for commercial jet pilots (and travelers)is generally related to &lt;a href=&quot;https://en.wikipedia.org/wiki/Cosmic_ray&quot; rel=&quot;nofollow noreferrer&quot;&gt;cosmic radiation&lt;/a&gt; and ultraviolet radiation from the sun. The sources are already quite distant, and the practical distances we can achieve on Earth won't make any appreciable difference here, so we can neglect distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Time&lt;/strong&gt; (duration of exposure) is already somewhat limited by the duration of flights, but the cumulative effect over multiple flights is what we're generally concerned about when we discuss &quot;pilot's radiation exposure&quot;.&lt;br&gt;&#xA;As their career requires them to fly, and the nature of jets means they'll be flying at high altitude there's not much that can be done with time, except perhaps having a very short career or not accepting a large number of flights. These options are not economically attractive if flying is your career.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That leaves &lt;strong&gt;shielding&lt;/strong&gt;. Pilots sacrifice the benefit of shielding (from the Earth's atmosphere) as they climb: The atmosphere is less dense and there is less of it between the pilot and the background radiation, therefore their exposure is increased.&lt;br&gt;&#xA;It's here that improvements can at least theoretically be made: The pilots and passengers already gain some shielding from the structure of the aircraft, but not nearly as much as 30,000 feet of atmosphere provides. The aircraft could be constructed with additional radiation-shielding materials (lead foil for example, and UV-attenuating tints in the windows) but doing so would add a significant amount of weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with most radiation shielding situations it ultimately becomes an economic trade-off: You implement shielding to bring the exposure (dose) down to an acceptable level given the time and distance constraints you're working within.&lt;br&gt;&#xA;The additional dose received by pilots &lt;a href=&quot;https://aviation.stackexchange.com/questions/15823/how-much-radiation-is-an-airline-pilot-exposed-to-in-a-year&quot;&gt;is already extremely low&lt;/a&gt;, and adding shielding to reduce it further would not give a huge increase in safety. The costs (in terms of aircraft design, construction, and operating cost to carry the additional weight) would exceed the cost of treating the relatively minor complications such as skin cancer which &lt;em&gt;may&lt;/em&gt; result from the additional exposure over a lifetime career of flying.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If all of that was too much to read, the short answer to your question is &quot;The best way to mitigate increased radiation exposure from flying is to remain at low altitudes.&quot; (Similar to how the best way to mitigate the increased radiation from living in Denver, Colorado at ~5,000 feet above MSL is to move to New Orleans, LA at 7 feet &lt;em&gt;below&lt;/em&gt; MSL.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next best thing would be to fly less frequently or on shorter legs (to reduce the duration of exposure).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-23T20:29:08.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25538" PostTypeId="2" ParentId="25531" CreationDate="2016-02-23T21:23:19.480" Score="7" Body="&lt;p&gt;In general, combining an empty wing with a full fuselage will give the highest stresses in the wing spar at positive and negative load factors. If the wing tanks held fuel, the weight of the fuel mass would reduce the wing spar bending moment inboard of the tanks at the same load factor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, details depend on the particular configuration. Make also sure you look at the most forward c.g. location and at the added load from aileron deflections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, don't assume that the critical load case of one design will also be the critical of another. Please look at cases in all corners of the envelope to make sure you do catch the critical one.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-02-23T21:23:19.480" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25539" PostTypeId="2" ParentId="25529" CreationDate="2016-02-23T23:49:13.987" Score="5" Body="&lt;p&gt;Polyhedral wings are used in aircraft for various reasons, mainly to improve roll stability without significant change in the overall wing design.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The original design of the F-4 Phantom (which started as a 'super F3' had a constant swept wing with anhedral. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uzE3e.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uzE3e.jpg&quot; alt=&quot;F4 prototype&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By U.S. Navy - U.S. Navy National Museum of Naval Aviation photo No. 1996.253.7320.028, Public Domain, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=24564607&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=24564607&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, wind tunnel tests indicated stability problems, which were were overcome with giving the outer wings a 12$^\circ$ dihedral, corresponding to a 3$^\circ$ overall (with changes in wing sweep too). This saved a major redesign of the wing, while also allowing the spar to pass below the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Another example of this is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-12&quot; rel=&quot;nofollow noreferrer&quot;&gt;Antonov An-12 'Cub'&lt;/a&gt;. The early prototypes had a straight high wing. However, test flights showed the aircraft having poor lateral and longitudinal stability, which was remedied by increasing anhedral on the outer wing panels. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nEpxL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nEpxL.jpg&quot; alt=&quot;An-12&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &lt;a href=&quot;//commons.wikimedia.org/wiki/User:Sefjo&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;User:Sefjo&quot;&gt;Sefjo&lt;/a&gt; - Own work, CC BY-SA 3.0, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=29397593&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=29397593&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The F-4U Corsair had polyhedral wings as the the designers had to keep the landing gear short enough, while at the same time &lt;a href=&quot;https://aviation.stackexchange.com/questions/21027/whats-the-advantage-of-the-f4u-corsairs-gull-wing-design&quot;&gt;have enough ground clearance for the huge propeller&lt;/a&gt; used.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-24T17:16:48.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25541" PostTypeId="1" CreationDate="2016-02-24T09:19:36.760" Score="3" ViewCount="2829" Body="&lt;p&gt;I need help picking an airfoil. I'm an artist and have limited knowledge of such things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's for a game with an aircraft similar to an Edge 540 / Extra 300.&#xA;Unfortunately I have a limited selection of airfoils though and need some suggestions for both wing and tail airfoils. (Don't have the ClCdCm for the real Edge)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do have access to many (not all) of the airfoils listed on this site though.&#xA;&lt;a href=&quot;https://aerodynamics.lr.tudelft.nl/cgi-bin/afCDb&quot; rel=&quot;nofollow&quot;&gt;https://aerodynamics.lr.tudelft.nl/cgi-bin/afCDb&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any guidance would be appreciated!&lt;/p&gt;&#xA;" OwnerUserId="13681" LastEditorUserId="12220" LastEditDate="2016-02-24T13:46:48.930" LastActivityDate="2016-02-25T09:32:44.380" Title="What is the best airfoil for Edge 540 Style Aircraft?" Tags="&lt;airfoil&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25542" PostTypeId="2" ParentId="25516" CreationDate="2016-02-24T11:57:08.237" Score="5" Body="&lt;p&gt;Extending bogardpd's answer: moving the fuel from the center to the wings will also upset the weight and balance. When the plane rolls, since the mass is further away from the rotation center, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Moment_of_inertia&quot; rel=&quot;noreferrer&quot;&gt;moment of inertia&lt;/a&gt; is increased. Which means slower response and a need for stronger wings, which means more weight, which means even stronger wings...... You get the idea.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-02-24T11:57:08.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25543" PostTypeId="1" AcceptedAnswerId="25555" CreationDate="2016-02-24T14:50:35.100" Score="4" ViewCount="3034" Body="&lt;p&gt;When you buy a book of government approach plates, or a Terminal Procedures Publication (TPP) it comes with a legend and other supplemental documents along with it. Now that a lot of pilots are using digital flight bags like ForeFlight it's easy to overlook this stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I need is a PDF of these materials, but after a lot of searching I'm just not finding it. Does anyone know if the FAA publishes this digitally? &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/&quot; rel=&quot;nofollow&quot;&gt;This page&lt;/a&gt; mentions that it's available, but I don't see the download for it.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="12720" LastEditDate="2016-02-24T23:39:04.887" LastActivityDate="2017-06-15T04:31:48.143" Title="Where can a PDF of the TPP legend and supplemental materials be found?" Tags="&lt;faa&gt;&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25545" PostTypeId="1" CreationDate="2016-02-24T15:37:46.637" Score="4" ViewCount="193" Body="&lt;p&gt;In moto racing, they use tire warmer to keep tires hot when the tire is not running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular weather conditions (e.g. heavy snow), aircraft require de-icing operation after staying parked for few tenth of minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do any device to protect the wings and other parts of the aircraft requiring to be free from ice before take off from icing and possibly keeping those parts above icing temperature exist? It could save some deicing time (and de-icing fluid) by reducing the amount of ice accumulated while the aircraft is on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: When asking the question, I was thinking of airliners between two legs in winter in Canada (with jetbridge connected, only few tenth of minutes before next scheduled leg, international airport ground support available,... and snow and icing conditions). I don't think the question should be restricited to this case, but it should take it into account.&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="3394" LastEditDate="2016-02-24T22:34:57.080" LastActivityDate="2016-02-24T22:34:57.080" Title="Do wing warmers exist?" Tags="&lt;ground-operations&gt;&lt;anti-ice&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25546" PostTypeId="1" AcceptedAnswerId="25549" CreationDate="2016-02-24T16:50:03.473" Score="8" ViewCount="2353" Body="&lt;p&gt;I've read that they try to keep it short. But on other sites and documentaries, it is said that they have to keep it long so that the birds don't look for food. Which is correct: short or long?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="8730" LastEditDate="2016-02-24T19:49:36.590" LastActivityDate="2021-03-24T18:22:14.050" Title="How high do they cut the grass on airports?" Tags="&lt;ground-operations&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25548" PostTypeId="2" ParentId="25546" CreationDate="2016-02-24T17:02:49.073" Score="-5" Body="&lt;p&gt;It is very important to authorities keep the grass cut, as we can see at Cork Airport (courtesy of youtube).&#xA;Doing this, the airport signs can be seen clearly by the pilots, avoinding mainly runway incursions, and also keeping far, as much as it can, the birds and their nests. This previous measure sometimes does not work as we wanted, but it might help a lot decreasing the bird hazardous airside.&#xA;After cutting the grass, the ground personnel will perform a runway inspection to clean it from debris.&lt;a href=&quot;https://i.stack.imgur.com/DV7Rr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DV7Rr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-02-24T17:02:49.073" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25549" PostTypeId="2" ParentId="25546" CreationDate="2016-02-24T17:09:47.697" Score="11" Body="&lt;p&gt;It depends on the type of bird and mammal species in native to the area and also the type of grass used in turfing; some of them may not survive if mowed very closely. FAA's &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/wildlife/resources/media/2005_FAA_Manual_complete.pdf&quot;&gt;Wildlife Hazard Management Manual&lt;/a&gt; concedes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Species-specific responses may be expected.  ...  Airport managers &#xA;  need to work with airport wildlife biologists to determine what species of concern in regards to aircraft safety are in their area and what the habitat needs are for those species.   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For most airports, FAA recommends a height of 5-8&quot; of grass.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Considering bird, mammal and vegetation limitations, mowing at least monthly at a target of 5 - 8 inches may work in many airport environments as &#xA;  part of a wildlife hazard management program. ... Mowing at 5 - 8 inches should also reduce &#xA;  small mammal abundance.   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-24T17:09:47.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25550" PostTypeId="1" CreationDate="2016-02-24T17:43:37.650" Score="7" ViewCount="21991" Body="&lt;p&gt;I am looking at aircraft performance data. There are charts for &quot;Cruise Ceiling&quot; and &quot;Service Ceiling.&quot;  What is the difference?  (The cruise altitude is lower.)&lt;/p&gt;&#xA;" OwnerUserId="13684" LastEditorUserId="62" LastEditDate="2016-02-24T20:26:20.593" LastActivityDate="2018-04-15T01:36:01.650" Title="What is the difference between Cruise and Service ceilings?" Tags="&lt;aircraft-performance&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25551" PostTypeId="2" ParentId="25550" CreationDate="2016-02-24T18:05:44.017" Score="10" Body="&lt;p&gt;Ceiling refers to the density altitude the aircraft is capable of reaching under a set conditions (configutaion etc.). The main difference between service and cruise ceilings is the aircraft rate of climb at those altitudes. At service ceiling, the rate of climb is 100 fpm. From &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/pilot_handbook.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA pilot handbook&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The service ceiling is the altitude at which the aircraft is unable to climb at a rate greater than 100 feet per minute (fpm).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The cruise ceiling, on the other hand, is the altitude at which the maximum climb rate is 300 fpm, though I've not seen it used much. The absolute ceiling is the maximum altitude where the aircraft can sustain level flight. From the same document:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At the absolute ceiling, there is no excess of power and only one speed will allow steady, level flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The image below shows the data for A-10.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eegvT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eegvT.png&quot; alt=&quot;A-10 ceiling&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://forums.eagle.ru/showthread.php?t=94333&quot; rel=&quot;noreferrer&quot;&gt;forums.eagle.ru&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that these values depend on the aircraft configuration.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2018-04-15T01:36:01.650" LastActivityDate="2018-04-15T01:36:01.650" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25552" PostTypeId="2" ParentId="25545" CreationDate="2016-02-24T18:27:20.270" Score="5" Body="&lt;p&gt;The standard solution for keeping aircraft parts &quot;above icing temperature&quot; when on the ground is, &lt;a href=&quot;https://aviation.stackexchange.com/questions/25545/do-wing-warmers-exist#comment61396_25545&quot;&gt;as was pointed out in the comments&lt;/a&gt;, a nice heated hangar.&lt;br&gt;&#xA;This has the secondary benefit of keeping all the other components at a warmer temperature where they're more amenable to operating (gyros spin up better, wheel bearings rotate more easily, etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once outside of a hangar deicing fluid is used, and provides &quot;anti-icing&quot; protection for a specific period (the fluid's &quot;holdover time&quot;) - we discussed that in more detail &lt;a href=&quot;https://aviation.stackexchange.com/questions/1723/what-are-the-different-kinds-of-de-ice-fluid/&quot;&gt;on this question&lt;/a&gt;.&lt;br&gt;&#xA;Obviously once the aircraft has been exposed to icing conditions or snowfall for a period exceeding that holdover time it must be de-iced again as there is a chance for ice to begin accumulating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also the potential to use the aircraft's &lt;a href=&quot;https://en.wikipedia.org/wiki/Ice_protection_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;ice protection systems&lt;/a&gt; (in particular electro-thermal systems such as used in the Boeing 787 which heat the wing in the manner you allude to in your question), though I'm not aware if any systems are currently approved to be used in this way.&lt;br&gt;&#xA;One of the key challenges there would be verifying that the wing surface is indeed free of ice, snow, and frost - that's easy to do from the deicing truck (particularly since deicing fluid is tinted so you can see where it has been applied), but on a typical passenger jet the pilots can't see the wing from the cockpit, and poor visibility from blowing snow, fog, etc. may make the visual determination difficult from the cabin as well.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-24T18:27:20.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25553" PostTypeId="2" ParentId="25541" CreationDate="2016-02-24T18:29:13.617" Score="5" Body="&lt;p&gt;For the Extra 300 which has symmetrical airfoils:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZGUS6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZGUS6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Extra 300, image by Ampbomber (source: &lt;a href=&quot;http://www.rcgroups.com/forums/thumbgallery.php?do=threadgallery&amp;amp;t=424898&quot; rel=&quot;nofollow noreferrer&quot;&gt;rcgroups.net&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.extraaircraft.com/docs/tech-manuals/MM300S/CH06.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;service manual&lt;/a&gt; of the Extra 300S:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing: from MA 15S (root) to MA 12S (tip). This change in profile allows for good performance both at low and high airspeeds.&lt;/li&gt;&#xA;&lt;li&gt;Tail, for the 3 surfaces: - &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=fx711530-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wortmann FX 71-L-150/30&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Wing airfoils characteristics seems not available online. On X-Plane.org forum (&lt;a href=&quot;http://forums.x-plane.org/index.php?showtopic=64289&quot; rel=&quot;nofollow noreferrer&quot;&gt;How X-Plane Uses Reynolds Number&lt;/a&gt;), it is suggested to replace the airfoils by &lt;a href=&quot;http://www.windandwet.com/windturbine/airfoil_plotter/index.php?airfoil=naca0015.dat&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA 0015&lt;/a&gt; and &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=n0012-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;0012&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the pitching moment coefficient &lt;em&gt;Cm&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Cm&lt;/em&gt; is null for a symmetrical airfoil (no camber).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Manufacturer manuals:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.extraaircraft.com/techservice.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Maintenance manual&lt;/a&gt;, in particular the &lt;a href=&quot;http://www.extraaircraft.com/docs/tech-manuals/MM300/CH57.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;chapter for the wings&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.extraaircraft.com/docs/service/POH_300L_20120419_CUS.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot's Operating Handbook&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Similar project:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On &lt;a href=&quot;http://jsbsim.sourceforge.net/Newsletter_3_2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;SourceForge&lt;/a&gt;: &lt;em&gt;Building an Aerobatics Aircraft for JSBSim: The Su-26&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As an additional information, a &lt;a href=&quot;http://m-selig.ae.illinois.edu/pubs/RaoUhligSelig-2012-AIAA-2012-2768.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;study&lt;/a&gt; was conducted to evaluate the lift coefficient of the wing (or maybe with the tail) and the lift / drag curve, at a reduced scale:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LwkFa.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LwkFa.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Experimentally determined drag polar and lift curve for the Extra 300 (Figure 7)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The scale change introduces a different &lt;a href=&quot;https://en.wikipedia.org/wiki/Reynolds_number&quot; rel=&quot;nofollow noreferrer&quot;&gt;Reynolds number&lt;/a&gt;, unknown adjustments must be made to extrapolate to full scale.&lt;/li&gt;&#xA;&lt;li&gt;The curves are incomplete (alpha max undetermined).&lt;/li&gt;&#xA;&lt;li&gt;The L/D ratio close to 2 is very low compared to the actual performances.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-02-25T09:32:44.380" LastActivityDate="2016-02-25T09:32:44.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25554" PostTypeId="1" AcceptedAnswerId="25775" CreationDate="2016-02-24T20:01:23.603" Score="11" ViewCount="10965" Body="&lt;p&gt;According to FAR 61.57, the regulation requires different experience requirements when a pilot uses FTD or ATD for their experience minimums. So I have tried to look up the difference between those two but I don't really understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Advisory Circular 61-136A, the definition of ATD is a training device, other than a FFS or FTD, that includes&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The definition of FTD, according to FAR Part 1, is also &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They look pretty much same to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could you give me the examples of those two?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="4197" LastEditDate="2016-02-25T21:22:47.307" LastActivityDate="2021-04-29T17:02:53.623" Title="What is the difference between an aviation training device (ATD) and a flight training device (FTD)?" Tags="&lt;flight-training&gt;&lt;far-61&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25555" PostTypeId="2" ParentId="25543" CreationDate="2016-02-24T20:27:51.127" Score="2" Body="&lt;p&gt;Apparently the file you are looking for is &lt;code&gt;FRNTMATTER.PDF&lt;/code&gt;, located in the &quot;D&quot; download file.&lt;p&gt;   &lt;a href=&quot;http://www.aeronav.faa.gov/d-tpp/1603/product_files/DDTPPD_201603.zip&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;DDTPPD_201603.zip&lt;/strong&gt;&lt;/a&gt;&lt;p&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(but it still looks like you have to download the 900MB ZIP file just to get that one important file)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The file that @JonathanWalters &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow&quot;&gt;referenced&lt;/a&gt; has very similar information in a much smaller download and a different format.  But there are differences between the two. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recommend downloading both the Chart Users guide at the FRNTMATTER.PDF file, and judging for yourself which one (or both) best has the info you are after.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2016-02-25T15:16:32.210" LastActivityDate="2016-02-25T15:16:32.210" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25556" PostTypeId="1" AcceptedAnswerId="25558" CreationDate="2016-02-24T20:46:50.283" Score="5" ViewCount="1502" Body="&lt;p&gt;My understanding is that the Concorde was equipped with a system that automatically lowered the aircraft to a safe altitude if cabin pressure was lost. I know such emergency never occurred in its history but did the Concorde have the range to make it to the closest airport if say this happened in the middle of the Atlantic. With a range figure of approximately $6500$ km at Mach $2.0$ and $50000$+ feet cruise, it is not clear that this bird would make it to land in such an emergency given it was terribly inefficient at low speeds and altitudes. What happen if this emergency had ever happened?&lt;/p&gt;&#xA;" OwnerDisplayName="user13363" LastEditorUserId="8022" LastEditDate="2016-02-25T04:10:08.113" LastActivityDate="2016-02-25T04:10:08.113" Title="What would have happened when the Concorde's low-pressure emergency system brought it lower mid-flight?" Tags="&lt;emergency&gt;&lt;cabin-pressure&gt;&lt;concorde&gt;&lt;range&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25557" PostTypeId="2" ParentId="25541" CreationDate="2016-02-24T20:55:15.267" Score="4" Body="&lt;p&gt;There are a few things to consider for a good aerobatic airfoil. The transition between attached and separated airflow has a big influence for spins or snap rolls, and a good aerobatic airfoil needs only a small change in AoA (angle of attack) to fully transition between the two. To achieve this, it helps to shape the forward part similar to an ellipse (a &lt;a href=&quot;https://en.wikipedia.org/wiki/Lemniscate&quot; rel=&quot;nofollow&quot;&gt;lemniscatic&lt;/a&gt; function, to be precise), and to use a straight line for the last 70% to 80% of chord. The goal is to have a &lt;a href=&quot;http://www.cfd-online.com/Wiki/Stratford&amp;#39;s_separation_criterion&quot; rel=&quot;nofollow&quot;&gt;Stratford pressure rise&lt;/a&gt; on those 70% to 80% which gives the maximum possible pressure gradient without separation. Increase AoA just a little, and you have fully separated flow over three quarters of the wing chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When all works as planned, you can get the plane out of a spin by applying rudder at, say, 45° before the fuselage points in the desired direction and get out of the spin within 10° of that direction. Same goes for snap rolls, they get really snappy. It is a real pleasure to fly such planes, but you need some discipline. There are no aerodynamic warnings before you stall, and stalling comes immediately. On the other side, with the limited lift loss of such an airfoil and the powerful engines of aerobatic airplanes, stalling is no big issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next thing to consider is relative thickness. Modern aerobatic aircraft are rated ±10g (note that FAR/JAR only requires ±6g in the aerobatic category), so a thick root airfoil helps to keep the structural mass down. On the other hand, maximum lift is possible with a thickness around 12%, so the compromise is to taper the wing from 15% at the root to 12% at the tips. The airfoil numbers given by mins refer to the relative thickness as percent of chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;None of the airfoils in your collection (which looks awfully like an older version of Michael S. Selig's &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/coord_database.html&quot; rel=&quot;nofollow&quot;&gt;UUIC database&lt;/a&gt;) will fit well. Go ahead and design one with &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot; rel=&quot;nofollow&quot;&gt;XFOIL&lt;/a&gt; and use the calculated polar. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-24T21:11:07.560" LastActivityDate="2016-02-24T21:11:07.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25558" PostTypeId="2" ParentId="25556" CreationDate="2016-02-24T21:22:22.390" Score="7" Body="&lt;p&gt;The pilots had a clear procedure to follow for an emergency descent, but this procedure was not automated by a machine. (It's actually quite complicated because Concorde had no speed brakes. So it requires negotiation with air traffic control for a clear descent path---not much point in doing an emergency descent if you crash into another aircraft on your way down).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde was actually fitted with very small windows, so that a powerful air pump would be able to hold a pressure differential against the outflow in the event of one window loss.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hear more from a Concorde pilot at: &lt;a href=&quot;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&quot;&gt;http://omegataupodcast.net/2015/02/166-flying-the-concorde/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several diversion airfields on the transatlantic route; KEF, YQX, and SJF are the most famous.&lt;/p&gt;&#xA;" OwnerUserId="8565" LastActivityDate="2016-02-24T21:22:22.390" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25559" PostTypeId="2" ParentId="25550" CreationDate="2016-02-24T21:34:39.410" Score="1" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ceiling_%28aeronautics%29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Service ceiling&lt;/a&gt; is generally understood as the maximum altitude at which the highest vertical speed drops below 0.5 m/s or 100 ft/min. This assumes a clean aircraft flown at the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8365/difference-between-best-rate-of-climb-and-maximum-rate-of-climb/8368#8368&quot;&gt;best rate of climb&lt;/a&gt; airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cruise ceiling is the maximum altitude at cruise speed. Cruise speed is one of the design speeds as defined by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=bee4d1f3c800be2fe6ac43067f296405&amp;amp;mc=true&amp;amp;node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1335&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR Part 25, §25.335&lt;/a&gt; and is determined by the manufacturer. Also, the remaining climb speed at cruise ceiling might differ and is defined by the manufacturer if a cruise ceiling is given at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the cruise speed of an aircraft is generally higher than the best rate of climb speed, the cruise ceiling is below the service ceiling of that aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-02-24T21:34:39.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25560" PostTypeId="2" ParentId="25556" CreationDate="2016-02-24T22:31:05.010" Score="9" Body="&lt;p&gt;I'm answering a point in a comment by the OP, rather than answering the question itself directly - but I do think it's totally relevant.  Feel free to vote accordingly :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.concordesst.com/history/destinations.html&quot;&gt;This list&lt;/a&gt; provides a list of Concorde destinations.  I am assuming that it is complete.  I have not gone through every route but looking down the list suggests that GOOY-SBGL (Dakar to Rio) is the route with the longest ocean crossing.  &lt;a href=&quot;http://forums.flightsimlabs.com/index.php?/topic/4607-concorde-routes-in-current-airacs/&quot;&gt;This list&lt;/a&gt; seems to confirm this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde did not fly the southerly Pacific routes, I guess because it would not be capable of diverting in exactly the situation you ask about.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suitable diversions on that route would be FHAW (Wideawake on Ascension Island), SBNT (Natal), SBRF (Recife) and SBSV (Salvador). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.gcmap.com/&quot;&gt;Using this tool&lt;/a&gt;, we can see that GOOY-SBNT is 1870nm and it's all ocean between them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.movable-type.co.uk/scripts/latlong.html&quot;&gt;Using this tool&lt;/a&gt;, we can calculate that the mid-point of GOOY-SBNT is at 10° 26′ 47″ N, 026° 29′ 44″ W.  We can also calculate that the midpoint to FHAW is 732nm and the midpoint to SBNT is 587nm.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So a reasonable guess (without access to the original flight plans) is that the &lt;strong&gt;maximum distance from a diversion&lt;/strong&gt; is to SBNT from the midpoint which is &lt;strong&gt;587nm&lt;/strong&gt;.  Easily done, even at 10,000 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before the midpoint, I guess they would have returned to GOOY since it is closer than FHAW.  Therefore, I also guess that FHAW would only have been considered if SBNT &lt;strong&gt;and&lt;/strong&gt; GOOY were not available - most unlikely.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I have now found a longer one!  KLAX (Los Angeles) to PHNL (Honolulu).  This one's easy.  The Great Circle mapper shows us it's 2220nm.  There is nowhere to divert between those two so the new greatest distance is &lt;strong&gt;1110nm&lt;/strong&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concordes' max range was about 3900nm so as long as it was about 60% efficient at 10,000 feet compared to cruise (1110 / ( 3900/2) plus a bit for go-around time), the diversion was no problem.  Although inefficient at lower levels, I doubt it was less than 60%.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-02-24T23:12:25.900" LastActivityDate="2016-02-24T23:12:25.900" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25562" PostTypeId="2" ParentId="25543" CreationDate="2016-02-24T22:49:00.270" Score="2" Body="&lt;p&gt;Much of the information is available on &lt;a href=&quot;https://www.faa.gov&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA.gov&lt;/a&gt;, in a handy web-based format in a document called the &quot;&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aero Guide&lt;/a&gt;&quot;, or as a PDF download called the &quot;&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Aero Guide provides a digital document of the reference information provided with both the VFR and IFR paper aeronautical charts and publications, as well as other information not included with the charts. For example, much (if not all) of the same information on Approach Lighting Systems is included in the Guide. However, some other information found in the TERPS publications is not available, such as the Inoperative Components Table.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a screen cap of one of the legends available in the Aero Guide on the &lt;code&gt;TPP Symbols&lt;/code&gt; tab (or in the PDF):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/OYwsE.jpg&quot; alt=&quot;legend&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a web-based version follow &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the link to the Aero Guide&lt;/a&gt; and click on the &lt;code&gt;TPP&lt;/code&gt; or &lt;code&gt;TPP Symbols&lt;/code&gt; tabs for the TPP information you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the PDF: as quoted from the 'product description' on the Aero Guide page:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Provided here is the Aeronautical Chart User's Guide in a web-based format. This web-based version is designed to easily reference chart symbology while providing access for all devices. For now, the downloadable PDF version is still available at the bottom of this page.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That link to the downloadable PDF is found at the bottom of the &lt;code&gt;Intro&lt;/code&gt; tab. &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This is the current direct link.&lt;/a&gt; Go to the bottom of that page (although not all the way down into the generic FAA.gov info) and look for the &quot;Aeronautical Chart User's Guide&quot; link. This document is about 22 MB in size.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-06-15T04:31:48.143" LastActivityDate="2017-06-15T04:31:48.143" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25564" PostTypeId="1" AcceptedAnswerId="26575" CreationDate="2016-02-25T01:55:53.133" Score="3" ViewCount="520" Body="&lt;p&gt;I've heard it said many times that &quot;everything has a backup&quot; in commercial planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about the fuel inerting system (injecting nitrogen in the fuel tank). Does it have a backup? Is it somehow failsafe all by itself?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="13754" LastEditDate="2016-03-31T13:13:12.350" LastActivityDate="2016-03-31T17:57:42.353" Title="Is there a backup to fuel inerting systems?" Tags="&lt;safety&gt;&lt;aircraft-systems&gt;&lt;fuel-tanks&gt;&lt;fuel-inerting-system&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25565" PostTypeId="5" CreationDate="2016-02-25T02:00:29.353" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-25T02:00:29.353" LastActivityDate="2016-02-25T02:00:29.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25566" PostTypeId="4" CreationDate="2016-02-25T02:00:29.353" Score="0" Body="A fuel inerting system renders the fuel tank inert, typically by injecting nitrogen gas, such that the oxygen content in the fuel tank is low and does not support combustion." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-25T02:48:46.990" LastActivityDate="2016-02-25T02:48:46.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25569" PostTypeId="1" AcceptedAnswerId="25571" CreationDate="2016-02-25T11:19:13.863" Score="9" ViewCount="1111" Body="&lt;p&gt;Aircrafts operating at high altitude falls into several categories:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wings with high aspect ratio (Global Hawk, TR-1, Scaled Composite Proteus,...)&lt;/li&gt;&#xA;&lt;li&gt;High velocity aircraft (Concorde, A-12, X-51,...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aircraft falling into those two categories cruise between 15km and 30km high.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Balloons (up to 50km high)&lt;/li&gt;&#xA;&lt;li&gt;Suborbital aircraft (X-15, Space Ship Two), performing their mission between 80 and 120km high.&lt;/li&gt;&#xA;&lt;li&gt;higher resides low earth orbit, and thus satellites which can hardly be qualified as aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I cannot find any aircraft designed to perform its mission at an altitude between 50km and 80km, which corresponds more or less to the mesosphere. Is there any aircraft designed to perform its mission into this 30km wide slice of atmosphere? What is the usefulness of this slice for aviation?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="69" LastEditDate="2016-02-29T01:08:39.370" LastActivityDate="2016-02-29T16:15:24.457" Title="Are there any aircraft designed to operate between an altitude of 50-80km?" Tags="&lt;aircraft-design&gt;&lt;high-altitude&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25570" PostTypeId="1" CreationDate="2016-02-25T17:15:13.183" Score="4" ViewCount="177" Body="&lt;p&gt;Depending on the cracked layer, there would be some actions from the crew.&#xA;The inner layer seems to be simple to identify, but if the middle and/or outer layer is cracked, how will pilots identify the right crack's position?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-02-25T18:18:18.957" Title="How can pilots identify, in flight, the cracked layer(inner/middle/outer) from an impaired windshield?" Tags="&lt;windscreen&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25571" PostTypeId="2" ParentId="25569" CreationDate="2016-02-25T17:33:49.830" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there any aircraft designed to perform its mission into this 30km wide slice of atmosphere? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(between 50km and 80km) - apart from some experimental rocket planes and so on, I can't think of any. The main problem is there's so little air - very little opportunity to generate lift, and very little air to run a jet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory it should be possible for a winged aircraft to fly up there (it is below the &lt;a href=&quot;https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_line&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kármán line&lt;/a&gt;) but the engineering difficulties would seem to make this impractical.  For more detail I'd recommend the top answer for this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9188/what-determines-the-maximum-altitude-a-plane-can-reach&quot;&gt;What determines the maximum altitude a plane can reach?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the usefulness of this slice for aviation?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If it were possible, it would be useful for futuristic or military things like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;spy planes like the SR-71 but higher and faster&lt;/li&gt;&#xA;&lt;li&gt;super-fast suborbital transport&lt;/li&gt;&#xA;&lt;li&gt;passing through on getting into orbit - &lt;a href=&quot;https://en.wikipedia.org/wiki/Single-stage-to-orbit&quot; rel=&quot;nofollow noreferrer&quot;&gt;single stage to orbit&lt;/a&gt;&#xA;vehicles for example.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(All of these examples are pipe dreams at the moment of course.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-25T17:33:49.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25572" PostTypeId="1" AcceptedAnswerId="25574" CreationDate="2016-02-25T17:43:06.840" Score="11" ViewCount="10610" Body="&lt;p&gt;I was thinking that red lights on the antennas on buildings help aircraft to see if there are tall objects in the ground. Is this right?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/YsS3L.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YsS3L.jpg&quot; alt=&quot;normal hazard light&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-02-28T13:13:17.410" LastActivityDate="2016-02-29T05:41:04.090" Title="Is it true that the red lights on building antennas help the aircraft &quot;detect/visualize&quot; ground objects?" Tags="&lt;safety&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25574" PostTypeId="2" ParentId="25572" CreationDate="2016-02-25T17:50:49.313" Score="31" Body="&lt;p&gt;Those lights are used to show obstacles that may interfere with the aircraft's course, such as antennas, buildings, wind turbines, and they are mandatory.&#xA;The name of those lights is Aircraft Warning Lights, and here is an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_warning_lights&quot;&gt;article from Wikipedia about them&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="9276" LastEditDate="2016-02-26T12:27:03.377" LastActivityDate="2016-02-26T12:27:03.377" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25575" PostTypeId="2" ParentId="25572" CreationDate="2016-02-25T18:03:53.663" Score="17" Body="&lt;p&gt;Yes, the lighting is helpful for collision avoidance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The red lights are helpful, but the white strobes can be even better for visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I am flying very low to the ground I am far more concerned about towers and windmills (or occasionally high tension power lines) than buildings. Fortunately all of my &lt;em&gt;really&lt;/em&gt; low flying for work is done during daylight hours, but in heavy overcast or other low-light conditions the lights are very helpful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most tall buildings are in congested areas and most flight operations will be required to maintain an altitude of 1000 feet or more above such structures. The presence of towers in excess of 500 feet, and especially in excess of 1000 feet, in uncongested areas posses a much more credible threat to VFR low level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA describes the standards for structure and tower lighting in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_70_7460-1L_.pdf&quot; rel=&quot;nofollow&quot;&gt;AC70/7460-1L&lt;/a&gt;. Generally, any structure that exceeds 200 ft AGL should be marked and/or lighted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that, though the lighting may be mandatory, it may be &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_70_7460-1L_.pdf&quot; rel=&quot;nofollow&quot;&gt;NOTAM&lt;/a&gt;ed out of service.&#xA;For example:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;code&gt;!SFF 02/009 SFF OBST TOWER LGT (ASR 1060807) 473535.00N1171750.00W (5.5NM S SFF) 3971.1FT (352.4FT AGL) OUT OF SERVICE&lt;/code&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-29T05:41:04.090" LastActivityDate="2016-02-29T05:41:04.090" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25576" PostTypeId="2" ParentId="9005" CreationDate="2016-02-25T18:16:22.050" Score="0" Body="&lt;p&gt;There is a threat that a large heavy jet could be stolen while parked at a remote airport at night (see Skywest aircraft stolen video). The crew entry doors and cockpit doors are not locked when not in flight. There are other means of entering the aircraft through electrical doors or cargo door area.&#xA; You do not need keys to start the aircraft and everything from starting the APU to the engines is done by toggle or push button switches. Airport security is the only protection and the fence line. &#xA;  Its just a matter of time before its done and flown into the closest large living structure after takeoff. 9-2-2014 10 &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2741428/Officials-warn-ELEVEN-missing-airplanes-Libya-used-carry-terrorist-attack-9-11-anniversary.html&quot; rel=&quot;nofollow&quot;&gt;Airbus aircraft stolen from Libya&lt;/a&gt;, 5-25-2003 &lt;a href=&quot;https://en.wikipedia.org/wiki/2003_Boeing_727-223_disappearance&quot; rel=&quot;nofollow&quot;&gt;727 stolen all these aircraft are still missing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="13697" LastEditorUserId="14613" LastEditDate="2016-06-01T22:37:16.300" LastActivityDate="2016-06-01T22:37:16.300" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25577" PostTypeId="2" ParentId="25570" CreationDate="2016-02-25T18:18:18.957" Score="3" Body="&lt;p&gt;It is possible to identify whether the crack affects the inner layer by sliding over it with nail or something sharp like pen. If the layer is cracked, the slight indenting in the surface can be felt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I can tell, there is no way to tell whether the outer or middle layer is affected with any useful degree of certainty. It is also not possible to ascertain how many layers are cracked. So usually the procedure is so that if the inner layer is not affected, you can continue and fix the issue at destination and if the inner layer is affected, you have to conservatively assume all layers may be affected and descend.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-02-25T18:18:18.957" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25579" PostTypeId="2" ParentId="25572" CreationDate="2016-02-25T18:28:05.493" Score="5" Body="&lt;p&gt;To answer your question directly, no, they are not used to indicate that you are too close to the ground.  Some of them are over 1500 feet high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are used so you do not fly into them for obvious reasons or fly too close to them for less obvious reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Some are powerful transmitters and can interfere with the systems on the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Towers often have support wires which extend a long way from the obstacle with the light and do not have lights themselves.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Too close to the ground is figured out by looking; by the altimeter; by charts and by planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The red light just means &quot;keep away!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/Research/Rvs/Article/EMI.html&quot;&gt;Some incidents and analysis of interference and even crashes attributed to high intensity EMR.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://catless.ncl.ac.uk/Risks/5.58.html#subj2&quot;&gt;Some follow up on the Blackhawk crashes.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whilst &lt;a href=&quot;https://www.icheme.org/communities/subject_groups/safety%20and%20loss%20prevention/resources/hazards%20archive/~/media/Documents/Subject%20Groups/Safety_Loss_Prevention/Hazards%20Archive/XX/XX-Paper-62.pdf&quot;&gt;this paper&lt;/a&gt; focusses primarily on the ability of high powered EMR sources to cause ignition sparks up to 30kms away (!), it also shows how dangerous they are up to hundreds of metres away.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anyone remains unconvinced that powerful transmitters need to be avoided by aircraft, please let me know and I'll do some more digging, but for now, I have an &quot;all nighter&quot; I need to pull to deliver a project tomorrow so I may be some time....&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-02-25T21:55:49.120" LastActivityDate="2016-02-25T21:55:49.120" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="25580" PostTypeId="1" AcceptedAnswerId="25596" CreationDate="2016-02-25T20:04:35.937" Score="10" ViewCount="2342" Body="&lt;p&gt;Regular airliners use JET A-1 fuel. However, I've seen that military aircraft, i.e., Airforce or Navy; use a different kind of fuel called JP-N, where N is a number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason why this happens? If those other fuels have different properties, which are them to be better than the JET A-1 fuel properties?&lt;/p&gt;&#xA;" OwnerUserId="8407" LastActivityDate="2018-12-13T00:53:33.190" Title="Why do military aircraft use a different kind of aviation fuel?" Tags="&lt;airliner&gt;&lt;military&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25582" PostTypeId="1" CreationDate="2016-02-25T20:17:08.513" Score="0" ViewCount="843" Body="&lt;p&gt;I was recently on a flight and the the engines started after push back has been initiated. I was always under the impression that the process required a GAU to feed pressurised air or use of the APU. &#xA;But the APU wouldn't be used at a major London airport when ground services are available?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How did they start then?&lt;/p&gt;&#xA;" OwnerUserId="13555" LastEditorUserId="12220" LastEditDate="2016-02-25T21:40:28.920" LastActivityDate="2016-02-25T21:40:28.920" Title="Is it possible to start the engines while on push back?" Tags="&lt;jet-engine&gt;&lt;engine-starting&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-02-25T21:34:13.237" ContentLicense="CC BY-SA 3.0" />
  <row Id="25583" PostTypeId="2" ParentId="25358" CreationDate="2016-02-25T20:22:00.223" Score="5" Body="&lt;p&gt;This type of terminals are called &quot;Satellite Terminals&quot;. Passengers are &lt;strong&gt;usually&lt;/strong&gt; processed in a central building while aircraft are parked in remote docks. The satellite buildings are connected with the central building (if any) through tunnels or any kind or collective transportation (e.g. bus). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These terminals have a wide range of advantages and disadvantages when compared with more frequent types of terminals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Advantages:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Suitable for high traffic airports and hubs with a large number of connecting flights.&lt;/li&gt;&#xA;&lt;li&gt;Easiness for the aircraft to maneuver on ground.&lt;/li&gt;&#xA;&lt;li&gt;Easy separation of passengers flows (e.g. international pax, national pax, regional pax).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Disadvantages:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;High investment and maintenance of transportation services.&lt;/li&gt;&#xA;&lt;li&gt;Acces congestion at peak-times.&lt;/li&gt;&#xA;&lt;li&gt;Early check-in.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Munich (MUC) or Madrid (MAD) are some of the airports that have implemented this system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The photo you show seems like a very special kind of satellite terminal with multiple remote &quot;gates&quot; and are probably managed by a bus that travels through the road connecting all of them.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastActivityDate="2016-02-25T20:22:00.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25584" PostTypeId="1" CreationDate="2016-02-25T20:22:50.450" Score="22" ViewCount="11124" Body="&lt;p&gt;Even at remote terminals as discussed &lt;a href=&quot;https://aviation.stackexchange.com/a/25359/1696&quot;&gt;in this answer&lt;/a&gt; it seems there's a preference for using a jet bridge to get passengers to and from the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0soE4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0soE4.jpg&quot; alt=&quot;Remote terminals with jet bridges&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can't the passengers just be bussed directly to the aircraft rather than the remote terminals?&lt;br&gt;&#xA;Why the use of a jet bridge here if they can use stairs at other times?  &lt;/p&gt;&#xA;" OwnerUserId="13555" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-29T15:32:49.667" Title="Why is dropping off passengers on the ramp by bus not more common?" Tags="&lt;passenger&gt;&lt;boarding&gt;" AnswerCount="4" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25585" PostTypeId="2" ParentId="25584" CreationDate="2016-02-25T20:42:02.183" Score="46" Body="&lt;p&gt;The use of a jet bridge has several major advantages over loading passengers from the ramp via portable staircases or built-in &quot;air stairs&quot;, among them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Boarding of handicapped passengers&lt;/strong&gt;&lt;br&gt;&#xA;Not all passengers &lt;em&gt;can&lt;/em&gt; use stairs: a jet bridge allows passengers with limited mobility, particularly those confined to wheelchairs, to board and disembark from the same level as the passenger deck.&lt;br&gt;&#xA;Accommodating these passengers from the ramp would require some kind of lift mechanism to raise them to the passenger deck of the aircraft - this is typically accomplished elsewhere in the terminal when a jet bridge is used, e.g. via passenger elevators in the ticketing area, or in the type of design shown in your question, via an elevator in each &quot;mini-terminal&quot;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Passenger shelter&lt;/strong&gt;&lt;br&gt;&#xA;Boarding from the ramp may work well on a beautiful spring day, but in less favorable conditions (rain, snow, temperature extremes) most passengers would not find the experience to be enjoyable. The jet bridge provides an enclosed and relatively climate-controlled route from the terminal to the aircraft.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Passenger Safety&lt;/strong&gt;&lt;br&gt;&#xA;Airport ramps are inherently dangerous places: Aircraft are starting their engines, being pushed back for departure, etc. and ground support vehicles are moving at all times carrying luggage, cargo, catering supplies, etc. to and from the aircraft. In addition to the ongoing movement there is a great deal of noise from these operations.&lt;br&gt;&#xA;Bringing passengers into this environment represents an inherent liability risk: Someone could be struck by a support vehicle, or injured by jet blast. A jet bridge is an enclosed area away from these dangers, providing an improvement in passenger safety.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Airport Security&lt;/strong&gt;&lt;br&gt;&#xA;A great deal of effort goes into ensuring that unauthorized persons do not have access to the airside facilities at an airport. Bringing passengers into this area represents a security risk, as even a ticketed passenger could be intent on causing disruption or damage once airside.&lt;br&gt;&#xA;A passenger wandering off on the ramp would represent both a safety hazard (as the passenger could be injured) and a security hazard (as the passenger could perform any number of malicious acts before they are located).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="64" LastEditorUserId="595" LastEditDate="2016-02-25T21:06:34.817" LastActivityDate="2016-02-25T21:06:34.817" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25586" PostTypeId="2" ParentId="25582" CreationDate="2016-02-25T21:13:52.917" Score="1" Body="&lt;p&gt;Aircraft engines are started using the APU or a Airstart Cart. The GPU is for electrical power only and the engines are started off air power. It may be a Airstart was not available or they were running late on the block time and they blocked  using the APU to start the engines to make the block time. After engine start and before takeoff the crew will shut down the APU. Most US airlines start their engine off APU air unless the APU is not working then they will start off a Airstart Cart. &lt;/p&gt;&#xA;" OwnerUserId="13697" LastActivityDate="2016-02-25T21:13:52.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25587" PostTypeId="1" AcceptedAnswerId="25594" CreationDate="2016-02-25T21:21:15.730" Score="12" ViewCount="28795" Body="&lt;p&gt;Where does the final approach segment begin on an ILS approach? It may not be as simple as it sounds to answer. The reason I ask is because I've found some support for at least two answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One is that final begins when passing the glide slope intercept point a the last no lower than altitude for the approach. This is the point denoted by the lightning bolt arrow on government charts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/HBJfCAh.png&quot; alt=&quot;glide slope intercept&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another answer I've heard is that it begins when glide slope has be intercepted within the limitations of the glide slope and on an approach segment. For the example plate above, this would mean that if the glide slope were intercepted between SILKY and JAKOR the pilot would be considered to be past the final approach fix for all intents and purposes and might even configure the airplane for landing at that point rather than passing JAKOR at the published glide slope intercept.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think there are valid arguments for both, but I'd apprecate more insight and references on the topic.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2019-10-25T19:50:49.463" Title="Where does the final approach segment begin on an ILS approach?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25589" PostTypeId="2" ParentId="25587" CreationDate="2016-02-25T21:53:48.980" Score="6" Body="&lt;p&gt;It's pretty easy to answer as  best I can determine: The Final Approach Segment begins at the Final Approach Fix. On FAA/NACO charts this is shown on the profile view with the Maltese cross:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wlnnA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wlnnA.png&quot; alt=&quot;LGA VOR 04 profile view&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;lightning bolt arrow&quot; (or as the FAA calls it, the &quot;zigzag line&quot;) designates the precision approach glideslope intercept altitude&#xA;This is usually coincident with the final approach fix (and the specified altitude serves as the minimum crossing altitude for the final approach fix if the glideslope is inopertive or not in use), but it does not appear on non-precision approach charts, as shown above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final approach fix may also be marked in the plan view with the annotation &lt;code&gt;(FAF)&lt;/code&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may have intercepted the glideslope before the FAF as you describe in your second scenario (particularly on a continuous-descent profile) or you may have done a dive-and-drive to that point because the glideslope is out of service before starting your final descent as in your first scenario, but for purposes of the approach segments the FAF marks the beginning of the final approach &lt;em&gt;segment&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-02-25T21:53:48.980" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25590" PostTypeId="1" AcceptedAnswerId="25591" CreationDate="2016-02-25T22:23:03.113" Score="8" ViewCount="8932" Body="&lt;p&gt;Specifically for a piston general aviation aircraft, is there a recommended distance from the runway to fly the downwind leg? Does this change based on the speed of the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-02-25T23:44:37.337" LastActivityDate="2020-12-24T12:41:42.920" Title="In the traffic pattern, what is the appropriate distance from the runway for the downwind leg?" Tags="&lt;general-aviation&gt;&lt;traffic-pattern&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25591" PostTypeId="2" ParentId="25590" CreationDate="2016-02-25T22:30:06.843" Score="4" Body="&lt;p&gt;Most instructors say that (in a low wing plane) you should see the runway on the tip of the wing or between the tip and 1/4 in the wing. AOPA has a &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/awp/media/education/safety%20advisor%20non-towered%20airports.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;nice over view of non towered airports here&lt;/a&gt;. This &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/09_afh_ch7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA brief states it should be flown 1/2 to 1 mile out&lt;/a&gt; (page 7-4 of FAA Airplane Flying Handbook, FAA-H-8083-3B). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This leg should be&#xA;  approximately 1/2 to 1 mile out from the landing runway,&#xA;  and at the specified traffic pattern altitude.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="30388" LastEditDate="2018-04-10T20:39:16.603" LastActivityDate="2018-04-10T20:39:16.603" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25592" PostTypeId="2" ParentId="25590" CreationDate="2016-02-25T22:31:37.090" Score="2" Body="&lt;p&gt;There are multiple considerations, among them: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Other aircraft in the pattern (that may be slower or faster than you): you want to maintain your position, not getting too close to planes ahead of you, nor slowing down planes behind you.&lt;/li&gt;&#xA;&lt;li&gt;The descent rate of your aircraft:  I was taught to descend 25% from TPA on downwind, 25% on base, and 50% on final. (typically from a 1,000 ft TPA, that is 250ft / 250ft / 500ft)&lt;/li&gt;&#xA;&lt;li&gt;The turning rate of your aircraft: You want to make rectangular shaped patterns.  If you are too close, your patterns will be more oval shaped.  If you are too far, you will have a very long base leg.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-02-25T22:31:37.090" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25593" PostTypeId="2" ParentId="25587" CreationDate="2016-02-25T23:10:56.877" Score="3" Body="&lt;p&gt;The lightning bolt is the final approach fix for precision approaches and the Maltese cross is the final approach fix for non-precision approaches. &lt;/p&gt;&#xA;" OwnerUserId="12929" LastEditorUserId="12929" LastEditDate="2016-02-26T02:38:11.220" LastActivityDate="2016-02-26T02:38:11.220" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25594" PostTypeId="2" ParentId="25587" CreationDate="2016-02-25T23:11:14.597" Score="14" Body="&lt;p&gt;No arguments needed, it's very specifically defined. According to the FAA's &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; under &lt;em&gt;SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. Final Approach− The segment between the final approach fix or point&#xA;  and the runway, airport, or missed approach point. (See ICAO term&#xA;  FINAL APPROACH SEGMENT.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it starts at the FAF, which is defined in the same document as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FINAL APPROACH FIX− The fix from which the final approach (IFR) to an&#xA;  airport is executed and which identifies the beginning of the final&#xA;  approach segment. It is designated on Government charts by the Maltese&#xA;  Cross symbol for nonprecision approaches and the lightning bolt&#xA;  symbol, designating the PFAF, for precision approaches; or when ATC directs a&#xA;  lower-than-published glideslope/path or vertical path intercept&#xA;  altitude, it is the resultant actual point of the glideslope/path or&#xA;  vertical path intercept.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In your example, that means the final approach segment starts at JAKOR. I may be wrong here, but your original thought might have been that the final approach starts when you're established on the glideslope, which could be outside JAKOR. That makes sense in a general way, but it isn't how the term is defined.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-02-25T23:11:14.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25595" PostTypeId="2" ParentId="25590" CreationDate="2016-02-25T23:30:41.660" Score="2" Body="&lt;p&gt;&quot;Within gliding distance&quot; is one common rule that many instructors teach. It would be embarrassing to have an engine failure in the pattern and not make it to the runway :-) More seriously, you tend to make a lot of configuration changes in the pattern so the risk of something going wrong is higher, therefore within gliding range is usually a good place to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That doesn't mean being in a position to glide the remaining downwind, base and final legs to land neatly on the numbers: it means gliding to &lt;em&gt;somewhere&lt;/em&gt; on the runway you can safely land (or even to a taxiway if need be). (The FAA's &lt;a href=&quot;http://www.faa.gov/training_testing/testing/test_standards/media/faa-s-8081-12c.pdf&quot; rel=&quot;nofollow&quot;&gt;commercial pilot test standards&lt;/a&gt; require the applicant to glide to a landing from the downwind leg starting at 1000 AGL.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there are lots of variables and you may have to fly a wider (or tighter) pattern at certain times or at certain airports for any number of reasons: traffic, ATC instructions, noise abatement etc.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-02-26T15:42:03.980" LastActivityDate="2016-02-26T15:42:03.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25596" PostTypeId="2" ParentId="25580" CreationDate="2016-02-26T00:08:01.237" Score="16" Body="&lt;p&gt;Military aircraft can and do fill up on civil Jet-A -- this is common at facilities where the extra expense of providing both Jet-A and JP-5 or JP-8 fuel isn't worthwhile.  However, the military jet fuel types do provide some advantages over Jet-A:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;JP-5 has a high flash point, improving its handling properties over civilian jet fuels.  This is important for fire safety in the close confines of an aircraft carrier.&lt;/li&gt;&#xA;&lt;li&gt;JP-8 is similar to civil jet fuel, but also has extra thermal stability additives in it.  This allows for longer-term storage under harsh field conditions, and better resistance to deposit formation in places like afterburners and fueldraulic movable nozzles where the fuel is exposed to high temperatures even before it's burned.  It also may be specified for properties such as cetane rating that are essential for proper performance of diesel reciprocating engines run from JP-8.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(I'm omitting JP-4 from this discussion as it's a wide-cut fuel, comparable to civil Jet-B, and was retired from USAF service in 1995.)&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2018-12-13T00:53:33.190" LastActivityDate="2018-12-13T00:53:33.190" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25597" PostTypeId="5" CreationDate="2016-02-26T00:54:58.643" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T00:54:58.643" LastActivityDate="2016-02-26T00:54:58.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25598" PostTypeId="4" CreationDate="2016-02-26T00:54:58.643" Score="0" Body="Questions regarding very lightweight powered aircraft." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:04:10.710" LastActivityDate="2016-02-26T01:04:10.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25599" PostTypeId="5" CreationDate="2016-02-26T00:59:07.413" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T00:59:07.413" LastActivityDate="2016-02-26T00:59:07.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25600" PostTypeId="4" CreationDate="2016-02-26T00:59:07.413" Score="0" Body="An elevator, in aircraft parlance, is a control surface responsible for pitching up or down." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:12:02.230" LastActivityDate="2016-02-26T01:12:02.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25601" PostTypeId="5" CreationDate="2016-02-26T01:02:46.507" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:02:46.507" LastActivityDate="2016-02-26T01:02:46.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25602" PostTypeId="4" CreationDate="2016-02-26T01:02:46.507" Score="0" Body="An airship, or dirigible, is a lighter-than-air powered craft typically using helium, or historically hydrogen, as the lifting gas." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:11:39.930" LastActivityDate="2016-02-26T01:11:39.930" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25603" PostTypeId="5" CreationDate="2016-02-26T01:05:28.630" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:05:28.630" LastActivityDate="2016-02-26T01:05:28.630" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25604" PostTypeId="4" CreationDate="2016-02-26T01:05:28.630" Score="0" Body="Questions about the round enclosures that house engines." OwnerUserId="3674" LastEditorUserId="22726" LastEditDate="2019-10-03T00:11:28.030" LastActivityDate="2019-10-03T00:11:28.030" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="25605" PostTypeId="5" CreationDate="2016-02-26T01:06:22.943" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:06:22.943" LastActivityDate="2016-02-26T01:06:22.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25606" PostTypeId="4" CreationDate="2016-02-26T01:06:22.943" Score="0" Body="Pitch is rotation about the lateral axis, which makes the nose point up or down." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:17:30.730" LastActivityDate="2016-02-26T01:17:30.730" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25607" PostTypeId="5" CreationDate="2016-02-26T01:09:06.193" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:09:06.193" LastActivityDate="2016-02-26T01:09:06.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25608" PostTypeId="4" CreationDate="2016-02-26T01:09:06.193" Score="0" Body="Use this tag for questions regarding UTC, zulu time, daylight savings time, or flight time." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:17:24.133" LastActivityDate="2016-02-26T01:17:24.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25609" PostTypeId="5" CreationDate="2016-02-26T01:19:16.347" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:19:16.347" LastActivityDate="2016-02-26T01:19:16.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25610" PostTypeId="4" CreationDate="2016-02-26T01:19:16.347" Score="0" Body="Pushback is the operation of pushing an aircraft back from the boarding gate, typically done with a tug." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:40:22.157" LastActivityDate="2016-02-26T01:40:22.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25611" PostTypeId="5" CreationDate="2016-02-26T01:27:24.160" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:27:24.160" LastActivityDate="2016-02-26T01:27:24.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25612" PostTypeId="4" CreationDate="2016-02-26T01:27:24.160" Score="0" Body="This is the ratio of air (by mass) that bypasses the combustion chamber of a jet engine, and instead is pushed through the outer shell of the engine by the main fan in the same way that a propeller pushes air." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:56:50.653" LastActivityDate="2016-02-26T01:56:50.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25613" PostTypeId="5" CreationDate="2016-02-26T01:29:46.487" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:29:46.487" LastActivityDate="2016-02-26T01:29:46.487" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25614" PostTypeId="4" CreationDate="2016-02-26T01:29:46.487" Score="0" Body="For questions about the location of engines on an aircraft." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:57:02.340" LastActivityDate="2016-02-26T01:57:02.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25615" PostTypeId="5" CreationDate="2016-02-26T01:31:53.283" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:31:53.283" LastActivityDate="2016-02-26T01:31:53.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25616" PostTypeId="4" CreationDate="2016-02-26T01:31:53.283" Score="0" Body="For questions about slanted vertical stabilizers in the shape of a V, which can act as both vertical and horizontal stabilizers. This can be a normal or inverted V-tail." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T01:57:56.737" LastActivityDate="2016-02-26T01:57:56.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25617" PostTypeId="5" CreationDate="2016-02-26T01:35:49.953" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-02-26T01:35:49.953" LastActivityDate="2016-02-26T01:35:49.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25618" PostTypeId="4" CreationDate="2016-02-26T01:35:49.953" Score="0" Body="Composite materials technically include any material made up of at least two constituents, such as metal alloys, but more commonly refer to plastic, ceramic, or carbon composites." OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-02-26T02:43:04.620" LastActivityDate="2016-02-26T02:43:04.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25619" PostTypeId="1" AcceptedAnswerId="25631" CreationDate="2016-02-26T01:55:38.477" Score="13" ViewCount="1459" Body="&lt;p&gt;Taking into account relevant elements like the fleet size or the type of flights (short or long haul, passengers or cargo, ...), do airlines use typical ratios between the number of aircraft and the number of pilots and attendants?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Clarification for the type of elements I'm looking for:&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;sup&gt;Northwings has 120 passenger aircraft and 720 pilots, this is comparable to other US airlines with modern aircraft (6 per passenger aircraft).&lt;/sup&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;sup&gt;There are between 4 and 10 Captains per passenger aircraft. This is dependent on local labor laws and unions.&lt;/sup&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;sup&gt;4 to 6 F/O for cargo aircraft (and no attendants because no passengers).&lt;/sup&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;sup&gt;A380 are atypical at Thing Air with 700 flight attendants for 10 aircraft of that type.&lt;/sup&gt;  &lt;/li&gt;&#xA;&lt;li&gt;&lt;sup&gt;Count 25% less for low cost airlines in the Middle East due to less restrictive labor laws and extended working time.&lt;/sup&gt;  &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Figures are for illustration, I've no idea of what the actual values are.)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="19" LastEditDate="2016-11-21T09:10:48.577" LastActivityDate="2016-11-21T09:10:48.577" Title="What is the relation between number of crew members (pilots and attendants) and fleet size in airlines?" Tags="&lt;regulations&gt;&lt;airlines&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25620" PostTypeId="1" AcceptedAnswerId="25624" CreationDate="2016-02-26T04:29:44.363" Score="11" ViewCount="16172" Body="&lt;p&gt;I'm interested to know how much time a descent and ascent to crusing altitude takes as part of a longer journey.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A standard jet-aircraft (for example a A340 or 777) flys for eight hours from City A to City C. While doing so it flies over City B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the same jet flys from City A to City C but as it approaches City B it descends and lands at B. The plane taxis to the gate. As soon as it's there it pushes back, requests take off and returns to the cruise flying to City C.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Approximately how much time is added to the journey by virtue of having descended, landed, taken-off and ascended to cruise ? Assume no ATC delays etc.&lt;/p&gt;&#xA;" OwnerUserId="4007" LastActivityDate="2016-02-26T08:02:40.650" Title="How much time does an landing/take-off add to an otherwise direct flight?" Tags="&lt;airline-operations&gt;&lt;flight-schedules&gt;&lt;time&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25621" PostTypeId="2" ParentId="11760" CreationDate="2016-02-26T05:35:17.310" Score="1" Body="&lt;p&gt;All the correct information has been added except one point. The engines nose spinners have a design painted on them. Once the engines are running the design is suppose to look like the eye of a bird of pray to scare off birds in flight. &#xA;  Does it work I can not say but they claim it does.&lt;/p&gt;&#xA;" OwnerUserId="13697" LastActivityDate="2016-02-26T05:35:17.310" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25622" PostTypeId="2" ParentId="25384" CreationDate="2016-02-26T05:55:13.153" Score="3" Body="&lt;p&gt;It is possible to overfill a wing. You fuel the aircraft when its wing is cold. Later as the aircraft sits on the ramp the outside temp increases causing the full to expand in an already full wing. So they have the overflow system dumps the excess fuel on the ramp. Its usually not a lot of fuel just a few gallons.&#xA;  It also prevents the fueler from over fueling the wind. It can sometime dump 50 gallons or more if the fueler it not paying attention.&lt;/p&gt;&#xA;" OwnerUserId="13697" LastActivityDate="2016-02-26T05:55:13.153" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25624" PostTypeId="2" ParentId="25620" CreationDate="2016-02-26T07:05:10.013" Score="13" Body="&lt;p&gt;Let's take the best case scenario to start with, and assume that the cruise ground speed of the airliner is around 400kts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For our best case, we also assume that the runway is lined up with the flight path and that the airspace is quiet so the plane is cleared &quot;straight in&quot; with no vectoring for separation or holding patterns.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Descent:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;A typical descent profile would start 100nm out, during which the plane would slow pretty uniformly from around 400kts to around 140kt. This gives an average groundspeed of 270kt. So this 100nm is covered in around 25 minutes rather the 15 minutes at full cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The descent has cost us only &lt;strong&gt;10 minutes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Taxi and turnaround:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;At a smallish (and well designed) airport the rollout and taxiing to the stand may only take 5 minutes, plus another 5 to attach the air bridge/stairs and open the door. Passenger and baggage turnaround would typically take around 30 minutes, but you have specifically excluded this in your question so we can ignore it. Then getting departure clearances, startup and taxiing to the active: say another 15 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this phase has cost more or less &lt;strong&gt;25 minutes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;3&quot;&gt;&#xA;&lt;li&gt;Take off and climb out:&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Again assuming we're cleared for immediate take off, it takes around 20 minutes to climb to cruise altitude, at an average ground speed of (say) 200 knots. This means we've covered about 70 miles, which the cruising aircraft would have covered in just over 10 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this final phase has cost us another &lt;strong&gt;10 minutes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Total for the best case scenario is &lt;strong&gt;45 minutes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the best case is not that likely. If the airspace is busy, holding for another 10 minutes before final approach, and 10 minutes further wait for departure and takeoff clearances, would not be surprising. And if the active runway is in the &quot;wrong&quot; direction or vectoring is needed for traffic or noise reasons, that can easily add another 10 minutes or so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in the non-best case scenario, a total loss of &lt;strong&gt;1h15 to 1h30&lt;/strong&gt; would not be unreasonable.&lt;/p&gt;&#xA;" OwnerUserId="4162" LastEditorUserId="4162" LastEditDate="2016-02-26T08:02:40.650" LastActivityDate="2016-02-26T08:02:40.650" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25625" PostTypeId="2" ParentId="12300" CreationDate="2016-02-26T12:40:09.370" Score="2" Body="&lt;p&gt;Something even more radical &lt;em&gt;has&lt;/em&gt; been considered! Airbus &lt;a href=&quot;http://arstechnica.co.uk/cars/2015/11/airbus-proposes-new-drop-in-airplane-cabin-modules-to-speed-up-boarding/&quot; rel=&quot;nofollow&quot;&gt;filed a patent on&lt;/a&gt; replacing the entire upper fuselage - seats, passengers and all - during a layover. The structural problems inherent in that idea look pretty hard though.&lt;/p&gt;&#xA;" OwnerUserId="13709" LastActivityDate="2016-02-26T12:40:09.370" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25626" PostTypeId="2" ParentId="12300" CreationDate="2016-02-26T12:57:38.603" Score="0" Body="&lt;p&gt;I for one would jump at the chance to arrive earlier, &quot;board&quot; earlier and sit in cramped airline seating even longer so the airline can save money. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you didn't pre-load the passengers in your capsules before the plane was ready to depart, there would be no time savings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No thanks. It's bad enough they hold you prisoner on the plane when there are hour + long delays in departure. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-02-26T12:57:38.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25627" PostTypeId="2" ParentId="25572" CreationDate="2016-02-26T13:00:48.847" Score="6" Body="&lt;p&gt;Before the lights were installed, &lt;a href=&quot;http://www.portsmouth.co.uk/heritage/plane-s-collision-showed-strength-of-local-mast-1-3675080&quot; rel=&quot;nofollow noreferrer&quot;&gt;this happened...&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qr6C9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qr6C9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/a6f5v.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a6f5v.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(second picture via &lt;a href=&quot;https://www.pinterest.com/pin/417145984210630603/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pinterest&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A better picture of this incident (a 1915 Sopwith Baby at Horsea Island in 1917) appears in the front of the 1925 edition of the &quot;Admiralty Handbook of Wireless Telegraphy&quot; in a slightly snarky advert, captioned &quot;A proof of the quality of Elwell masts&quot;.&lt;/p&gt;&#xA;" OwnerUserId="4068" LastEditorUserId="3627" LastEditDate="2016-02-26T23:44:21.193" LastActivityDate="2016-02-26T23:44:21.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25628" PostTypeId="2" ParentId="25584" CreationDate="2016-02-26T13:01:34.457" Score="13" Body="&lt;p&gt;Instead of built-in &quot;air stairs&quot; or portable staircases, &lt;a href=&quot;https://en.wikipedia.org/wiki/Mobile_lounge&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mobile lounge&lt;/a&gt; have been used for several airports to transfer passenger from terminal to planes directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jWUvr.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jWUvr.jpg&quot; alt=&quot;Plane-Mate in Dulles airport (Creditor)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Plane-Mate in Washington Dulles airport (&lt;a href=&quot;http://www.virtualtravelog.net/2003/02/the-mobile-lounges-at-dulles-international-airport/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Creditor&lt;/a&gt;)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;However for several reasons most of the mobile lounge has been replaced.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Rise of air transport: Number of flights and capacity of airliners has benn rising quickly in these decades. It require more mobile lounges to serve the passengers. Furthermore the road network within airport have to be upgraded if there are too many mobile lounges. Transferring passengers by People mover or walkway is cheaper and faster.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Trend of airport operation: Since airport security has been continuously rising in these decades, tourists stay much longer in the airport than before. Hence, airport operator are likely to create more retail area so that they can generate more income. The concept of airport lounge does not fit this trend.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Though mobile lounge has been kicked by Jet bridge, it is still used for many airports for special customers, eg: wheelchair tourists to airliners in remote stand. &lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2016-02-29T15:32:49.667" LastActivityDate="2016-02-29T15:32:49.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25630" PostTypeId="2" ParentId="25584" CreationDate="2016-02-26T14:11:24.763" Score="12" Body="&lt;p&gt;An additional complication not touched in the existing answers is the &lt;strong&gt;disparity in number of passengers that can be handled by an airliner and a bus.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A large bus might be able to accomodate somewhere on the order of 50-100 passengers comfortably while maintaining a reasonable turning radius and maneuverability as well as reasonable boarding and unboarding times, assuming luggage remains handled separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large aircraft can handle far more passengers than that. For example, an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380#Testing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus A380 can take 853 passengers&lt;/a&gt;, and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_767&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 767 can accomodate up to 375 persons&lt;/a&gt;. Even &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_MD-80&quot; rel=&quot;nofollow noreferrer&quot;&gt;the MD-80 can seat up to 172 passengers&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that &lt;strong&gt;you would need anywhere between four and seventeen bus roundtrips&lt;/strong&gt; to get everybody onto the plane (two for a big bus and a MD-80), as opposed to simply moving everybody through a single jet bridge at the gate. Intuitively, this would seem to take far longer, in turn reducing aircraft turnaround and thus driving costs up. While &lt;a href=&quot;https://aviation.stackexchange.com/a/12305/753&quot;&gt;the time to board passengers can still be used productively&lt;/a&gt;, I find it doubtful that the same could be said if the time to board passengers was at least several times longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft up to the number of passengers that can comfortably be accomodated by a single bus roundtrip, other issues (security, etc.) notwithstanding, boarding by bus remains a possibility without significantly impacting turnaround. But those types of aircraft tend to not be used for anything but short haul flights anyway.&lt;/p&gt;&#xA;" OwnerUserId="753" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-02-26T14:11:24.763" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25631" PostTypeId="2" ParentId="25619" CreationDate="2016-02-26T15:01:37.590" Score="7" Body="&lt;p&gt;My answer may not directly answer your question but from &lt;a href=&quot;http://web.mit.edu/airlinedata/www/Employees&amp;amp;Productivity.html&quot;&gt;MIT's The Airline Data Project&lt;/a&gt;, I extract data for year 2014 and put in table as follow:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Employees Per Aircraft                                  Southwest    United    American Airlines   Delta Airlines    Jetblue Airways&#xA;----------------------------------------------------------------------------------------------------------------------------------------&#xA;Pilots &amp;amp; Co-Pilots (Crews)                              6.0          8.3       6.8                 7.4               6.5&#xA;Flight Attendants (Crews)                               5.9          8.8       7.3                 6.8               5.0&#xA;Maintenance (Inhouse)                                   3.5          10.5      17.4                11.4              3.8&#xA;Passenger, Cargo and Aircraft Handling (Inhouse)        29.2         63.9      30.7                36.7              27.1&#xA;Other (Inhouse)                                         6.9          6.9       10.8                18.1              10.0&#xA;----------------------------------------------------------------------------------------------------------------------------------------&#xA;Total                                                   70.9         132.2     98.1                107.5             68.2&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;note that total number of crew does not add up with each type of crew in the table&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope it gives you some idea about the ratio of pilot and flight attendant&lt;/p&gt;&#xA;" OwnerUserId="679" LastActivityDate="2016-02-26T15:01:37.590" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25633" PostTypeId="1" CreationDate="2016-02-26T18:24:31.250" Score="4" ViewCount="348" Body="&lt;p&gt;Aispace is separated in sectors, and each one has its own frequency. What's the airspace capacity for procedural and radar services, for a single sector?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-04-11T23:06:20.783" Title="How many aircraft can an ATCo control simultaneously, on procedural and radar service?" Tags="&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;rules-of-the-air&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25634" PostTypeId="2" ParentId="25633" CreationDate="2016-02-26T19:33:56.000" Score="4" Body="&lt;p&gt;There's probably not a specific number.   The answer will probably end up being &quot;however many can do and maintain separation.&quot; Some sectors will include more complex maneuvering (more than one airport, several different approaches, both commercial and GA aircraft) so the airspace would have to be broken up into many smaller sectors with fewer aircraft in each to reduce workload. Whereas if you're talking about en-route, where the aircraft are not doing a lot of maneuvering the controller can probably deal with several times as many planes. If you think of arrivals at a busy airport, the airspace is broken into several different controllers, whereas often one guy in the tower is doing all of the landing clearances. That means he controls every single inbound flight whereas the approach controller is only juggling the portion that approach through his airspace. The workload per plane for the tower on landing is much lower since the approach controller will pass aircraft to him to him separated and already on ILS or with a visual on the runway. So all he is responsidle for is is making sure the runway is clear for each landing. In most situations tower only talks to the arrivals twice. Once to give clearance and then to pass them on to ground.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-04-11T23:06:20.783" LastActivityDate="2016-04-11T23:06:20.783" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25635" PostTypeId="2" ParentId="25584" CreationDate="2016-02-26T20:01:31.207" Score="5" Body="&lt;p&gt;The other answers address the question of why dropping passengers off on the apron by bus isn't common, but it does happen - mostly at smaller airports (for rural places with perhaps just one gate) and even at large busy hubs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are several reasons airlines sometimes board by having passengers walk to the plane and then either up a ramp or airstair:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Not enough gate space.  This could be because a flight that should have left is under some delay and taking up a gate, an inbound flight is early, a diverted aircraft has arrived, or there are simply too many scheduled flights right now.  For example, if a terminal was originally built to accommodate 10 certain size  aircraft but the airline expands its fleet to use a larger aircraft, such that the terminal can now serve only 9 at a time, they might occasionally or routinely bus passengers to and from that 10th flight.  This could also be a temporary situation lasting hours to months, caused by terminal construction for example.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Plane too small for a jetbridge.  This is the case with some smaller turboprop or jet planes in use by airlines.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Other unique situations.  For example, at LAX, customs in most terminals close after a certain time of day.  An arrival from Mexico to T7 at night will involve parking at T7 and the entire passenger group and flight crew getting on large busses and taken to customs at the main international terminal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="7365" LastActivityDate="2016-02-26T20:01:31.207" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25636" PostTypeId="1" AcceptedAnswerId="25640" CreationDate="2016-02-26T21:11:53.677" Score="17" ViewCount="2635" Body="&lt;p&gt;Historically regional jets (eg, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_717&quot;&gt;MD-95/B717&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CRJ700_series#CRJ700_series&quot;&gt;CRJ-700/900&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_ERJ_145_family&quot;&gt;ERJ-145&lt;/a&gt;, etc) have had their engines mounted near the rear of the fuselage.  But, recently, regional jets are increasingly using an under wing configuration (&lt;a href=&quot;https://en.wikipedia.org/wiki/Embraer_E-Jet_family&quot;&gt;E-170/175&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Sukhoi_Superjet_100&quot;&gt;Sukhoi SJ100&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Mitsubishi_Regional_Jet&quot;&gt;Mitsu MRJ700&lt;/a&gt; to name a few.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple related questions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why might this configuration be advantageous for small jets as opposed to the rear mounting configuration commonly used before?&lt;/li&gt;&#xA;&lt;li&gt;If it's advantageous, I assume technical problems are what stopped it from being implemented before.  So what has changed that allows manufacturers to use this configuration now?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="511" LastEditorUserId="22726" LastEditDate="2019-01-04T04:16:11.420" LastActivityDate="2019-01-04T04:16:11.420" Title="Why are modern regional jet designs shifting towards under wing engines?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;regional-jet&gt;" AnswerCount="3" CommentCount="13" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25637" PostTypeId="1" AcceptedAnswerId="25639" CreationDate="2016-02-26T21:44:45.930" Score="5" ViewCount="1107" Body="&lt;p&gt;Let's say you are going to do some maneuvers in a practice area, make a few touch and go landings at a non-towered airport, then return to your home airport...is it possible to file a VFR flight plan for this?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="64" LastEditDate="2016-02-26T23:04:55.927" LastActivityDate="2016-02-26T23:08:08.677" Title="Can I file a VFR flight plan for a training flight?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;usa&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25638" PostTypeId="1" CreationDate="2016-02-26T22:55:38.670" Score="1" ViewCount="526" Body="&lt;p&gt;I have an HSI, an OBS, and a GPS. I normally set my HSI to runway heading, my bug to the wind direction, and the GPS to destination airport/waypoint (which will give me my turn out heading). I don't normally move my OBS. Once I get in line to depart, I set my bug to my departure heading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For my coms I put the tower frequency in COM1 and the ground and guard in COM2. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a standard procedure for setting up your nav instruments and coms? Is there a better or more efficient method than what I am doing? I have been thinking I could set my OBS up for the approach and my second option in COM1 as CTAF or tower at the arrival airport. What does everyone think?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-02-28T09:55:29.387" Title="How do you set up your nav instruments and coms during ground operations and takeoff?" Tags="&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="6" ClosedDate="2016-02-27T15:58:34.147" ContentLicense="CC BY-SA 3.0" />
  <row Id="25639" PostTypeId="2" ParentId="25637" CreationDate="2016-02-26T23:08:08.677" Score="6" Body="&lt;p&gt;Absolutely. In fact it's not a bad idea to do so, if only to get some practice filing flight plans and using the system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US VFR flight plans are a search-and-rescue tool: They're only used if your aircraft is overdue to give the rescue folks information to help plan the search.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your particular case I would file a flight plan that lists your home airport as your departure and destination, with the airport you intend to use for your touch-and-go landings as an intermediate waypoint.  If you want to enter information on the nature of the flight (training, touch-and-gos at XXXX, etc.) in the remarks field you can do that too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Activate the flight plan when you depart, and close it when you return to your home airport. You can optionally also call Flight Service over the radio when you get to the touch-and-go airport to give them a position report and let them know you've reached that waypoint (I would do this on your way out of the area to return home, along with an ETA update if appropriate).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;As an alternative (or in addition to the VFR flight plan) you could get &lt;a href=&quot;https://aviation.stackexchange.com/questions/516/when-can-i-request-flight-following&quot;&gt;flight following&lt;/a&gt; from the ATC facility responsible for your airspace. Be aware that they may drop you and ask you to squawk VFR while you shoot your touch-and-gos since you'll probably be going off their radar, but you can always request service again when you start your return leg. &lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-26T23:08:08.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25640" PostTypeId="2" ParentId="25636" CreationDate="2016-02-26T23:37:18.917" Score="21" Body="&lt;p&gt;The underwing engine location allows for a lighter airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Placing the engines under/ahead of the wings brings these benefits:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Bending relief: Engine mass is closer to where lift is created, so the structure has less stress to carry around.&lt;/li&gt;&#xA;&lt;li&gt;Flutter suppression: Placing the engines ahead of the elastic axis of the wing shifts the flutter speed up, so the wing can be built less stiff.&lt;/li&gt;&#xA;&lt;li&gt;Better evacuation: With wing-mounted engines a rear door is possible to create a second point for emergency egress.&lt;/li&gt;&#xA;&lt;li&gt;Lower noise level in the rear cabin.&lt;/li&gt;&#xA;&lt;li&gt;More useable cabin space at the rear.&lt;/li&gt;&#xA;&lt;li&gt;Easier access to the engines for maintenance.&lt;/li&gt;&#xA;&lt;li&gt;Shorter piping for fuel and bleed air. Especially in the narrow fuselages of regional jets the air ducts for ventilation take a lot of valuable space.&lt;/li&gt;&#xA;&lt;li&gt;And don't discount psychology: The underwing engine design looks more like the bigger jets, which can be a big factor for some passengers. The airplane looks safer and more mature.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With modern CFD it is much easier to reduce the interference between the engine nacelles and the wing, so the biggest disadvantage of an underwing engine location can be reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that early designs for the Boeing 737 used rear-mounted engines. By relocating them under the wings, the structure could be made 700 kg lighter. Quote from &lt;a href=&quot;http://www.b737.org.uk/history.htm&quot;&gt;www.b737.co.uk&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Overall, the wing-mounted layout had a weight saving of 700Kgs over&#xA;  the equivalent “T-tail” design and had performance advantages.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The rear-mounted engines were a fad from the late Fifties (started by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle&quot;&gt;Sud Aviation Caravelle&lt;/a&gt;) to the mid-sixties and driven by the concern about the higher risk of low-mounted engines ingesting debris and the higher asymmetry in engine-out conditions. With more operational experience and more reliable engines, these concerns proved unfounded. Citing &lt;a href=&quot;http://www.b737.org.uk/history.htm&quot;&gt;www.b737.co.uk&lt;/a&gt; again:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Initial worries about the low mounted engines ingesting debris proved&#xA;  unfounded, this was demonstrated by the Boeing 720B whose inboard&#xA;  engines are lower than the 737's and had been in service for four&#xA;  years without significant problems.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Small business jets still prefer rear-mounted engines so they can operate from more airfields (on which the runway might not be as clean as those of big airports) and because the weight penalty of rear-mounted engines is less pronounced. Instead of bending and thrust loads, handling loads and manufacturability drive the minimum skin gauges on smaller jets.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-27T19:47:54.370" LastActivityDate="2016-02-27T19:47:54.370" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25641" PostTypeId="1" CreationDate="2016-02-27T00:04:16.317" Score="8" ViewCount="4170" Body="&lt;p&gt;In VFR flights from class C, I sometimes get &lt;code&gt;resume own navigation, altitude your discretion&lt;/code&gt; after departure and sometimes just &lt;code&gt;resume own navigation&lt;/code&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does &lt;code&gt;resume own navigation&lt;/code&gt; alone mean &lt;code&gt;altitude your direction&lt;/code&gt; as well?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume scenario below for KSNA and to be more specific:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot to Clearance Delivery: &lt;em&gt;529J with request&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearance Delivery: &lt;em&gt;529J go ahead&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot to Clearance Delivery: &lt;em&gt;529J is Cessna 172/u west side parking, requesting &#xA;El Toro departure to Chino with information Bravo&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clearance Delivery to Pilot: &lt;em&gt;After Departure turn left heading 080, Maintain VFR at or &lt;strong&gt;below 2400&lt;/strong&gt;, SoCal on 124.1, SQUAWK 0210&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot: &lt;em&gt;reads back …&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot starts taxi then take off with proper radio communication with ground and tower. After departure Tower hands pilot over to SoCal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilot to SoCal (initial call): SoCal 529J departed John Wayne, 1100 climbing, &lt;strong&gt;requesting 3000&lt;/strong&gt; to Chino&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SoCal to pilot:  &lt;em&gt;529J resume own navigation&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the confusion, sometime SoCal comes back with only resume own navigation. Does this mean pilot can climb to 3000 or altitude restriction for 2400 still valid?&lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="3455" LastEditDate="2016-03-03T22:03:54.230" LastActivityDate="2016-03-03T22:03:54.230" Title="Does &quot;resume own navigation&quot; also mean &quot;altitude your discretion&quot;?" Tags="&lt;visual-flight-rules&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25642" PostTypeId="2" ParentId="25636" CreationDate="2016-02-27T00:07:57.250" Score="5" Body="&lt;p&gt;There are a few reasons for the placement of the engines under wings. As most of the pros and cons have been already discussed elsewhere, I don't want to go into them, but I'll just point out some reasons for this trend.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;One important shift in the last two decades in airline industry is the use of high bypass engines, which have higher diameters and are quite difficult to place in the rear. As the trend appears to be towards higher bypass ratios, it makes more sense to put the engines under wings where engine size increase could be better accomodated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another point is that the aircraft today are not developed seperately for regional and national use, but developed as part of a family, which can be used in a variety of roles. &lt;a href=&quot;https://www.flightglobal.com/news/articles/crucial-choices-165492/&quot; rel=&quot;noreferrer&quot;&gt;Flighglobal points this out&lt;/a&gt; on its article on the Embraer E170:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The response reflects the shift in emphasis since 1998 away from a product geared solely to the regional airline market to a more robust family design with equal appeal to traditional mainline carriers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the 170 is not called ERJ 170, just the E-170; the dropping of the regional moniker is significant. Embraer considerd using a tail mounted engine for 170, but went with a wing mounted one as this design proved better.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The mounting of engines on the wing helps in reducing weight. Mounting engines on the tail needs beefier fuselage for thrust transfer and usually necessiates a T-tail due to engine location. This is somewhat cancelled by a shorter landing gear, but as the aircraft size increases, the weight savings become significant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;From the airline/customer point of view, the mounting of engine on the wing is better in two respects- reduced maintenance due to engine accesibility and reduced noise in cabin.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-27T00:07:57.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25643" PostTypeId="2" ParentId="25641" CreationDate="2016-02-27T00:25:07.650" Score="3" Body="&lt;p&gt;At this time, the definition of &quot;resume own navigation&quot; is very varied from group to group. ATC Controllers say that if there is an altitude restriction, they have to clear it. So safest thing to do is to ask for clarification if you had an altitude restriction/not told &quot;altitude your discretion&quot; that would continue into the &quot;resume own navigation&quot; exactly what you are doing now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/hottopics.aspx?id=39&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-02-27T02:11:35.650" LastActivityDate="2016-02-27T02:11:35.650" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25644" PostTypeId="1" CreationDate="2016-02-27T07:06:05.050" Score="3" ViewCount="871" Body="&lt;p&gt;What does the following mean and what ramifications does it have when purchasing an aircraft?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;term R/H-1958 HOURS SMOH@26/02/1988   - BULK STRIP 27/03/1998  ENGINE&#xA;  1472 SMOH&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does it mean the engine will be at its lide use and has to be replaced with another or am I correct that they replaced some parts to extend the time based on condition and will require a full overhaul 528 hors?&lt;/p&gt;&#xA;" OwnerUserId="13725" LastEditorUserId="3201" LastEditDate="2016-02-27T10:10:14.680" LastActivityDate="2016-02-27T22:22:12.707" Title="What is the meaning of &quot;Bulk Strip&quot;?" Tags="&lt;piston-engine&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25645" PostTypeId="1" AcceptedAnswerId="25647" CreationDate="2016-02-27T08:27:05.047" Score="28" ViewCount="91614" Body="&lt;p&gt;What metal alloy is used for the hot section of a jet engine? Specifically the exhaust nozzle? I have found mention of a titanium alloy and nickel alloy but nothing with that much detail. What sort of metals does one have to use to create something that can withstand temperatures of 650 degrees Celsius? Thanks&lt;/p&gt;&#xA;" OwnerUserId="13643" LastActivityDate="2019-02-04T19:41:51.967" Title="What material is used to make the hot sections of jet engines?" Tags="&lt;jet-engine&gt;&lt;aerospace-materials&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25646" PostTypeId="2" ParentId="25638" CreationDate="2016-02-27T11:09:05.410" Score="3" Body="&lt;p&gt;I think it is save to say that it is a good practice to &lt;strong&gt;do anything you can on the ground rather then doing it in the air.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;My setup:&lt;/em&gt; I usually end up with a similar set up as you do, though I don't use GPS much, but prefer hopping from one VOR to the next ;) (Well, I'll have to add that I'm not the most experienced pilot around here, for sure!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Basic principle&lt;/em&gt;: I try to follow the rule I mentioned up there: I try to decrease the workload in the air by doing it on the ground already. That's why we make our route up on the ground, not as we go (well, one of the many reasons). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say I have Com1 and Com2, each with a standby frequency as well as two Nav's, also each with a standby frequency: Before taxi, I'd have Com1 Active set up as tower and be listening and talking to Com2 to clearance, having ground in the standby. As soon as I have my clearance, I can put in my initial heading with the heading bug (not flying SIDs), as well as the Dep. frequency in Com1 Standby. This way I have all ground related stuff in Com2, all air related stuff in Com1. As for the Navs and the OBS: If there is a VOR at the airport I'm gonna put it in Nav2 and turn the OBS to initial takeoff heading (mostly runway heading). This is just as a support, &quot;heading&quot; still means pointing your nose to where the controller says, no matter what track the wind makes you actually fly. But then I know where I'm at and can already figure out what the wind is doing on my climb out. Nav1 goes to my first VOR, and depending whether I go direct or join an airway, I center the needle or set the OBS to the airway track respectively. The standby frequencies of the Navs are set to my second waypoint on Nav1, and whatever I think I'll need afterwards on Nav2. After takeoff I use Nav1 primarily to navigate, and Nav2 to verify my position (such a aircraft would usually have DME, so that you don't need to cross bear your position with two VORs, but if there is time to do so, why not).&#xA;In the air I usually don't use  the standby freqs much on the Coms, and just swap Com1 and Com2 when changing frequency. Before landing, the same thing counts as before takeoff: Take as much workload off in advance. Thus I'm setting up the coms (I got 3 spare frequencies when talking to approach or center or whatever, the'll all be filled in with usefull frequencies like ATIS, Tower and Ground), the Nav's for the approach (with missed approach in standby if available). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Well that was quite a novel, I hope you didn't fall asleep halfway through. This is what I do, and I get along with it quite well. I am not saying it is the 100% perfect thing to do, and (as Simon points out in his answer) you should do whatever you feel the most comfortable with. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summing up, I think &lt;strong&gt;doing as much as you can in advance is key in flying&lt;/strong&gt; (especially IFR), as it gives you more time in case you need it for something else to do.&lt;/p&gt;&#xA;" OwnerUserId="5592" LastEditorUserId="5592" LastEditDate="2016-02-28T09:55:29.387" LastActivityDate="2016-02-28T09:55:29.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25647" PostTypeId="2" ParentId="25645" CreationDate="2016-02-27T11:27:22.643" Score="42" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Fan: Aluminum, titanium, or stainless steel&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compressor: Nickel-, cobalt-, or iron-based alloys. Additive are aluminum and/or titanium, chromium, as well as rare earth elements like yttrium.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Combustion chamber: Superalloys with refractory metals such as tungsten, molybdenum, niobium, tantalum. Ceramics and ceramic-metal mixes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Turbine: Nickel-based superalloy, outside air is circulated through channels inside of the turbine blades. For lower pressure turbine blades iron-based superalloy or even stainless steel. The metals used for turbine blades are often grown as a single crystal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Exhaust nozzle: Nickel Inconel and stainless steel alloys.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Casing: Aluminum or polymer matrix materials.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The high-pressure turbine is, with the combustion chamber, very hot (more than the exhaust nozzle). You may read this &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbine_blade&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia article&lt;/a&gt; which has a short list of materials used for turbine blades (with &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbine_blade#List_of_turbine_blade_materials&quot; rel=&quot;nofollow noreferrer&quot;&gt;alloys names&lt;/a&gt; and cooling techniques).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Engine structure (turbofan)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uy9Ma.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uy9Ma.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbofan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An actual engine looks &lt;a href=&quot;https://i.stack.imgur.com/alPSm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;like that&lt;/a&gt; (CFM56 turbofan). It's easy to map the detailed elements to the simplified schematic. The fan pushes about one ton of cold air in the engine every second in high power turbofans. This is why temperatures and pressures can be so large after compression and after combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All quotes are from &lt;a href=&quot;http://er.jsc.nasa.gov/seh/ANASAGUIDETOENGINES%5B1%5D.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Nasa Guide To Engines&lt;/a&gt;, 2007.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1903, the Wright brothers built an aluminum&#xA;  block engine because of its light weight compared to cast iron. Its&#xA;  melting point of 660 °C was well above the engine’s operating&#xA;  temperature, so for them it was a good choice. However, aluminum could&#xA;  not be used in the hotter parts of a turbine engine where temperatures&#xA;  reach of 1800 °C or more because it would melt.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This typically does&#xA;  not get very hot (&amp;lt;150 °C) so aluminum, titanium, or stainless steel&#xA;  are all suitable for the fan blades. Most engines use titanium because&#xA;  it has a high strength-to-weight ratio, is corrosion and fatigue&#xA;  resistant, and would be able to withstand the impact of a bird strike.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.dailymail.co.uk/1/2018/04/20/02/2739414-5632767-The_FAA_has_ordered_ultrasonic_inspections_of_fan_blades_on_some-a-5_1524187433507.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fan example&lt;/a&gt; (with a fan blade missing after the engine blew apart).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Compressor section&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pressure of the air can be raised up to 30 times and the&#xA;  temperature, depending on the number of stages in the compressor, can&#xA;  rise to 1000 °C. Here the materials must have high strength at high&#xA;  temperatures; must resist fatigue, cracking, and oxidation; and also&#xA;  must resist “creep.” Creep is the tendency of a material to slowly&#xA;  change shape when stressed at high temperature. Since no single metal&#xA;  would have all the desired properties, an alloy (a mixture of metals)&#xA;  is used. Very high- temperature alloys are called superalloys and are&#xA;  generally nickel-, cobalt-, or iron-based alloys. Aluminum and/or&#xA;  titanium are added for strength, and chromium, as well as rare earth&#xA;  elements like yttrium, are added to improve corrosion resistance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/d/df/CFM56_High_Pressure_Compressor_Rotor.JPG/800px-CFM56_High_Pressure_Compressor_Rotor.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Compressor example&lt;/a&gt; (high pressure rotors)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Combustion chamber&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Temperatures can exceed 1800 °C and again superalloys are used, but&#xA;  without the titanium or aluminum for strength because there are no&#xA;  moving parts. Instead, refractory metals are often added to a&#xA;  superalloy. These are metals of unusually high resistance to heat,&#xA;  corrosion, and wear such as tungsten, molybdenum, niobium, tantalum,&#xA;  and rhenium. They are used in alloys and not as pure metals because&#xA;  they are among the densest of all the elements, a negative property&#xA;  when it comes to aircraft that need to keep weight to a minimum.&#xA;  Ceramics and ceramic-metal mixes are also used here because of their&#xA;  high heat resistance. We are familiar with pottery, tile, crucibles,&#xA;  and fire bricks as types of ceramics. They have very high melting&#xA;  points and don’t require the cooling systems like those needed to keep&#xA;  metals from melting so they make for lighter, less complicated engine&#xA;  parts. The down side is that they tend to fracture under stress, so&#xA;  engineers seek to create new ceramics composites that incorporate&#xA;  other materials to improve properties.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://leehamnews.com/wp-content/uploads/2016/12/TAPS-combustor-larger.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Combustion chamber example&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turbine&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YKcxt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YKcxt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;High-pressure turbine blade (source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Components_of_jet_engines&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The first set of turbine blades are in the highest pressure, hottest&#xA;  part of the gas flow and are generally made of nickel-based superalloy&#xA;  or ceramic blades. Unheated outside air is circulated through channels&#xA;  inside of the turbine blades to keep them from melting in this extreme&#xA;  environment. Further down the engine lower pressure turbine blades&#xA;  often sit. Since the gases have somewhat cooled by this point, the&#xA;  blades can be made of iron-based superalloy or even stainless steel.&#xA;  It is interesting to note that for strength, the metals used for&#xA;  turbine blades are often grown as a single crystal. A close look at&#xA;  most metals and alloys show that they are composed of crystals (also&#xA;  called “grains”), and the places where the crystals meet are called&#xA;  grain boundaries. A material is weaker at the grain boundaries than&#xA;  within the grains—especially at high temperatures— so turbine blades&#xA;  fashioned from metal formed as a single grain (no boundaries) are&#xA;  stronger.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.appropedia.org/Single_Crystal_Turbine_Blades&quot; rel=&quot;nofollow noreferrer&quot;&gt;single crystal material&lt;/a&gt; (known as &lt;em&gt;monocrystalline&lt;/em&gt; material in electronics) .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/CFM56_High_Pressure_Turbine_Vane.JPG/800px-CFM56_High_Pressure_Turbine_Vane.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turbine example&lt;/a&gt; (high pressure stator)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Exhaust&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bZnn0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bZnn0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Exhaust from Boeing 787 engine (GEnx, one of the world's largest jet engine - &lt;a href=&quot;https://blogs.mentor.com/jvandomelen/blog/2010/07/30/ultra-fast-power-switching-coming-soon-to-a-plane-near-you/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_handbook/media/FAA-8083-30_Ch05.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Aviation Maintenance Technician Handbook - FAA-8083-30&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Inconel and stainless steel alloys. The Inconel [nickel-chromium-iron]&#xA;  alloys are frequently used in turbine engines because of their ability&#xA;  to maintain their strength and corrosion resistance under extremely&#xA;  high temperature conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.altempalloys.com/inconel-alloys.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inconel details&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Casing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Although it need not withstand high temperatures like the core of the&#xA;  turbine, the materials here need to be strong enough that if a blade&#xA;  were to break off it would be contained within the casing and not&#xA;  enter the wing or cabin of the aircraft and cause further damage.&#xA;  Aluminum or some polymer matrix materials are used as engine casings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-02-04T19:41:51.967" LastActivityDate="2019-02-04T19:41:51.967" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="25648" PostTypeId="2" ParentId="25645" CreationDate="2016-02-27T11:31:17.593" Score="7" Body="&lt;p&gt;First, the hot section is not the nozzle, but the combustor and the high-pressure turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, 650°C is nothing for modern high-temperature alloys like &lt;a href=&quot;https://en.wikipedia.org/wiki/Inconel&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inconel&lt;/a&gt;. The top gas temperature in a modern jet turbine is more like 1500°C, and the turbine blades tolerate temperatures of around 1200°C. For military turbines and the temperature in the combustor, add a few hundred degrees on top of that. &lt;a href=&quot;http://www.thermopedia.com/content/759/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Film cooling&lt;/a&gt; allows to run high-performance turbines at a few hundred centigrades below the gas temperature. Steel would melt and other materials like &lt;a href=&quot;https://aviation.stackexchange.com/questions/11481/why-are-turbine-blades-not-made-out-of-titanium-only-compressor-blades&quot;&gt;titanium&lt;/a&gt; would quickly oxidize, and only nickel alloys or ceramics are up to the job. Being still too brittle for everyday use, ceramics have not managed to escape the laboratory, so nickel alloys is all we have for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A popular choice for gas turbines is &lt;a href=&quot;http://www.steelgr.com/Steel-Grades/High-Alloy/in-792.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Inconel 792&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-02-27T11:38:56.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25649" PostTypeId="2" ParentId="25638" CreationDate="2016-02-27T12:29:12.343" Score="2" Body="&lt;p&gt;I do think that the question is largely opinion based but paradoxically, that's why I'm offering an answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that the overriding principle should be:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's in a check list, the POH or otherwise mandated, then do it that way.  Not doing so could have legal, operational or insurance implications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it's not, then do &lt;strong&gt;whatever works for you&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you check that you haven't taxied to the wrong end of the runway (it's happened before) by checking that your heading bug is pointing at the runway you are about to enter or some other check which is in your setup, then keep doing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By all means, look for practical, actionable suggestions that make sense to you instantly then consider incorporating them but pilots changing habits, whether by choice or if required to do so, is a continued source of accidents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I do like @rbp comment to you about COM1 and COM2 being on the belly or the roof.  That's a good one I hadn't heard before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's fine to ask for opinions, although it might get the question closed, but how can you trust random strangers on the interweb thing?  Being consistent, logical and above all, true to the way you fly is I believe the most important thing by far.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2016-02-27T12:29:12.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25650" PostTypeId="1" AcceptedAnswerId="25758" CreationDate="2016-02-27T13:45:50.310" Score="14" ViewCount="731" Body="&lt;p&gt;Aerial navigation is designed to primarily use magnetic headings. Consider an international flight which flies a great circle route across the North Pole, or an aerial tour around the Atlantic area. What should the pilots do to avoid getting lost?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/351/how-are-vors-oriented-near-the-magnetic-poles&quot;&gt;This question&lt;/a&gt; asks about VOR alignment, and &lt;a href=&quot;https://aviation.stackexchange.com/questions/17282/is-the-heading-used-near-the-pole&quot;&gt;this question&lt;/a&gt; discusses the coordinate system used; but neither discuss what the pilots should do in the cockpit. How do you align the HSI? And what happens if GPS has malfunctioned?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-03-04T15:31:48.990" Title="What precautions should be taken when flying near the magnetic poles?" Tags="&lt;navigation&gt;" AnswerCount="1" CommentCount="12" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25651" PostTypeId="1" AcceptedAnswerId="25653" CreationDate="2016-02-27T14:27:29.183" Score="10" ViewCount="1691" Body="&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=Z1bcZF3vAEk&quot; rel=&quot;nofollow&quot;&gt;In this video&lt;/a&gt;, the tail cone is popped off as part of the evacuation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It stays attached on a lanyard which seems to be more of a hazard than letting it fall free.  Additionally, the slide doesn't deploy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's clear that the rear and front port exits are the safe ones, but did something go wrong here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(P.S.  I'm not talking about the actions of the pax, just about the tail slide).&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1467" LastEditDate="2019-11-14T09:14:48.107" LastActivityDate="2019-11-14T09:14:48.107" Title="Was this a successful deployment of an MD-88 tail cone evacuation slide?" Tags="&lt;evacuation&gt;&lt;dc-9-family&gt;&lt;md-80&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25652" PostTypeId="2" ParentId="25512" CreationDate="2016-02-27T16:02:35.763" Score="8" Body="&lt;p&gt;The high energy air that passes through the slots prevents boundary layer separation over the top surface of the flap. Though, this increases drag but it improves the stall characteristics of the airfoil. In other words, we can have higher maximum lift coefficient (Cl_max) by having higher maximum angle of attack (alpha_max). So, higher the number of slots higher Cl_max one could reach, there should be a limit. In case of a fixed weight of an aircraft,a higher lift coefficient implies that one can fly at lower speed before it stalls. A comparison between different types of flaps (up to double slotted)can be found in the book Aircraft Design and Performance by Anderson. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:&#xA;The same book. &lt;/p&gt;&#xA;" OwnerUserId="13652" LastActivityDate="2016-02-27T16:02:35.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25653" PostTypeId="2" ParentId="25651" CreationDate="2016-02-27T16:36:26.383" Score="8" Body="&lt;p&gt;Considering that the slide was not deployed, it is definitely unsuccessful. The MD-80 series (also the DC-9 and boeing 717) had tail cone assemblies which could be jettisioned in case of an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When operated, the tailcone is expected to swing to the left of the fuselage due to to its own weight because of the way it was rigged. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The jettison cone is attached to the slide through a lanyard, which passes through two eyelets in the tail cone and is attached to a spring in the middle of the cone. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As the jettison mechanism is activated, the tail cone is released and because of the way it is rigged, turns 90$^\circ$ and moves to the left of the aircraft to keep it from interfering with the slide deployment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As it falls, it pulls on the slide container via the slide lanyard, moving it so that it can inflate and delpoy, while the tail cone remains to one side of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can see it in the images below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VNIle.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VNIle.jpg&quot; alt=&quot;MD 88 J1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/IVm46.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IVm46.jpg&quot; alt=&quot;MD 88 J2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rL69W.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rL69W.jpg&quot; alt=&quot;MD 88 J3&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All images taken from &lt;a href=&quot;http://www.fomento.gob.es/NR/rdonlyres/E33E7C87-5D30-498D-BE8B-890250F7133E/37592/2004_045_IN_ENG.pdf&quot; rel=&quot;noreferrer&quot;&gt;Accident Report IN-045/2004&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the undeployed slide (in an MD-81) from the inside along with the lanyard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gX8Vd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gX8Vd.jpg&quot; alt=&quot;MD 88 J4&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://aircrewbuzz.blogspot.in/2009/09/ntsb-issues-probable-cause-report-for.html&quot; rel=&quot;noreferrer&quot;&gt;aircrewbuzz.blogspot.in&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The release can be made by three ways- there is an emergency handle on the aft bulkhead door, one at the end of the catwalk and another one in the exterior of the handle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the tail cone has pulled the lanyard, but the slide has failed to delpoy. While I'm not sure why the cone is hanging, it appears that the lanyard has snagged somwhere, probably in the cam rotator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: This would not be the first time the slide has &lt;a href=&quot;http://www.fss.aero/accident-reports/dvdfiles/US/1994-03-02-US.pdf&quot; rel=&quot;noreferrer&quot;&gt;failed to deploy/deployed unsuccesfully&lt;/a&gt; or &lt;a href=&quot;http://aircrewbuzz.blogspot.in/2009/09/ntsb-issues-probable-cause-report-for.html&quot; rel=&quot;noreferrer&quot;&gt;has deployed inadvertently&lt;/a&gt;. Also, see this discussion on the MD-88 tailcone jettison and slide deployment mechanism &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/5155944/#menu102&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-02-27T16:48:54.763" LastActivityDate="2016-02-27T16:48:54.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25654" PostTypeId="1" CreationDate="2016-02-27T16:54:39.173" Score="11" ViewCount="4348" Body="&lt;p&gt;Aircraft use GPS and &lt;a href=&quot;https://en.wikipedia.org/wiki/Inertial_navigation_system&quot; rel=&quot;noreferrer&quot;&gt;inertial navigation systems&lt;/a&gt; in combination. Sometimes INS needs alignment (i.e. to be told where it is AND what orientation it has). How can an aircraft be be aligned to true north for proper INS alignment? Are markings at the parking location good enough?&lt;/p&gt;&#xA;" OwnerUserId="13735" LastEditorUserId="12220" LastEditDate="2016-02-28T14:58:37.677" LastActivityDate="2021-05-05T14:28:47.960" Title="How can aircraft determine true north for inertial navigation systems?" Tags="&lt;navigation&gt;&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25655" PostTypeId="2" ParentId="25654" CreationDate="2016-02-27T20:20:42.393" Score="15" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;How can an aircraft be be aligned to true north for proper INS&#xA;alignment? Are markings at the parking location good enough?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A small 0.5° error in assumed heading translates into 10 NM error in computed position on the distance Madrid-Montreal (3,000 NM). As many other errors must be taken into account, north must be known to a higher degree to achieve this accuracy, and a better accuracy is also expected This cannot be done using simple markings.&lt;/p&gt;&#xA;&lt;p&gt;But true north is related to Earth spin axis, which can be accurately sensed by an INS using a gyroscope.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Inertial systems belong to two families: platform and strapdown:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In platform INS (PINS) accelerometers and gyros are mounted on a gimballed platform kept level and oriented to north by torque motors driven by gyros outputs.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In strapdown INS (SINS) these sensors are firmly fixed on the aircraft.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;PINS are mostly using &lt;a href=&quot;https://en.wikipedia.org/wiki/File:LN3-2A_Platform_MVC-876X.JPG&quot; rel=&quot;nofollow noreferrer&quot;&gt;momentum wheels&lt;/a&gt;. Recent gyros are SINS and not inertia-based, they usually measure length differences created by &lt;a href=&quot;https://en.wikipedia.org/wiki/Sagnac_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sagnac effect&lt;/a&gt; (&lt;a href=&quot;https://en.wikipedia.org/wiki/Fibre-optic_gyroscope&quot; rel=&quot;nofollow noreferrer&quot;&gt;fiber optic&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ring_laser_gyroscope&quot; rel=&quot;nofollow noreferrer&quot;&gt;ring laser&lt;/a&gt;, &lt;a href=&quot;https://www.mdpi.com/2072-666X/8/1/2/htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;acoustic&lt;/a&gt;...):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5lzyj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5lzyj.jpg&quot; alt=&quot;Ring laser gyros in AN/WSN-7 US Navy navigation system&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Ring laser gyros in AN/WSN-7 US Navy navigation system (&lt;a href=&quot;https://www.militaryaerospace.com/communications/article/16714471/honeywell-to-replace-ring-laser-gyros-to-keep-navy-anwsn7-shipboard-navigation-functioning&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Regardless of the type, alignment is similar and consists in sensing Earth spin axis and gravity, and is twofold: Leveling, then gyrocompassing.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Alignment principle&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Accelerometers and gyroscopes arrangement in an inertial system, and final orientation:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xeSkp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xeSkp.png&quot; alt=&quot;Accelerometers and gyroscopes arrangement&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Leveling&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Axes which in the end will point to north and east are in a first step leveled by tilting the assembly. Leveling solely involves accelerometers and gravity.&lt;/p&gt;&#xA;&lt;p&gt;Leveling is real for PINS, it gives the platform its working orientation, found by zeroing north and east accelerometer outputs while the unit is stationary. After alignment, accelerometers are able to directly sense accelerations along north, east and up directions.&lt;/p&gt;&#xA;&lt;p&gt;Leveling is virtual (software) for SINS. It consists in evaluating the initial orientation to build a transformation matrix. This matrix is used for projecting the values issued by tilted sensors onto a virtual level platform. The matrix is then constantly updated with orientation changes detected by gyros.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Gyrocompassing&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Likewise leveling, gyrocompassing is real or virtual according to the type of inertial system. Gyrocompassing goal is to determine true north using gyros.&lt;/p&gt;&#xA;&lt;p&gt;After leveling, for a stationary aircraft, north and east gyros (designated X and Y below) sense only Earth rotation, in quantities depending on their orientation relative to Earth spin axis:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5Y24I.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5Y24I.png&quot; alt=&quot;Inertial system with different headings relative to Earth&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;On the left hand picture, X gyro fully senses Earth rotation effects as it is aligned with spin axis, Y gyro doesn't detect any rotation.&lt;/li&gt;&#xA;&lt;li&gt;On the middle picture, the system has been rotated by 90°, the result is reversed.&lt;/li&gt;&#xA;&lt;li&gt;The right hand picture depicts the general case: Both gyros detect Earth rotation rate, but in quantities depending on the heading. X detects a rate proportional to the cosine of the heading, Y a rate proportional to the sine.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Finding north is done by rotating (virtual rotation for SINS) the leveled assembly about the vertical axis until the east gyro output is null, meaning its axis points to east or west. This ambiguity is removed by sensing rotation direction on the other axis which now points north or south.&lt;/p&gt;&#xA;&lt;p&gt;Earth rate detection depends on (cosine of the) latitude angle:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O70oi.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O70oi.png&quot; alt=&quot;Earth rotation rate sensing by an inertial system versus latitude&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Earth rotation rate sensing by an inertial system versus latitude&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Merging what we exposed above, the sensed rates Rx and Ry are given by:&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$$  \begin {cases}&#xA;Rx &amp;amp; = &amp;amp; \omega \times \cos \alpha \cos \phi \\&#xA;Ry &amp;amp; = &amp;amp; \omega \times \sin \alpha \cos \phi&#xA;\end {cases}$$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; is the constant for Earth spin rate, &lt;span class=&quot;math-container&quot;&gt;$\approx 15$&lt;/span&gt;°/hour (360° in a &lt;a href=&quot;https://astronomy.swin.edu.au/cosmos/s/Sidereal+Day&quot; rel=&quot;nofollow noreferrer&quot;&gt;sidereal day&lt;/a&gt;),&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\phi$&lt;/span&gt; is the latitude,&lt;/li&gt;&#xA;&lt;li&gt;&lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; is the heading of the aircraft (or of the reference axis).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;With two linear equations for two unknowns, finding latitude and heading is straight forward, the only condition is Rx and Ry are known. That is where the shoe pinches. Gyrocompassing is actually difficult and slow.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;Actual application of the principle is challenging&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;While the principle is simple, it's difficult to measure Rx and Ry. The reason is &lt;span class=&quot;math-container&quot;&gt;$\omega$&lt;/span&gt; is tiny (0.004°/s), measures must be repeated during a significant time. Five minutes is sufficient at the equator, but twenty minutes are not unusual at 45° latitude.&lt;/p&gt;&#xA;&lt;p&gt;The pilot can provide the current approximated latitude to allow this process to converge more quickly.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kEomp.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kEomp.gif&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Boeing 737, &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_management_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;FMS page&lt;/a&gt; used to enter the initial position estimate to speed up gyrocompassing&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;&lt;strong&gt;Sensor fusion, alignment in motion and loss of alignment&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Alignment may be facilitated, and subsequent measures can be improved by associating additional sources of data, and merging sources after filtering excessive divergence, this is known as &lt;a href=&quot;https://en.wikipedia.org/wiki/Sensor_fusion&quot; rel=&quot;nofollow noreferrer&quot;&gt;sensor fusion&lt;/a&gt; and IRS/GNSS hybridization. These sources include GNSS (position and Doppler velocity), magnetometers, air data, even Doppler velocities of known targets but that's more for underwater rovs to replace GNSS.&lt;/p&gt;&#xA;&lt;p&gt;The different sources allow to maintain the natural cumulated drift associated with the integration process, which is central to inertial positioning, below some threshold, e.g. thresholds fixed by required navigation performance procedures.&lt;/p&gt;&#xA;&lt;p&gt;In some conditions the inertial system can even be realigned in flight from GNSS position and Doppler velocity (e.g. &lt;a href=&quot;https://northropgrumman.litef.com/fileadmin/downloads/Datenblaetter/Datenblatt_LCR-110.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Northrop Grumman LCR-110&lt;/a&gt;). Such in-flight alignment should be common in the future.&lt;/p&gt;&#xA;&lt;p&gt;Level and north orientation are kept after alignment by adjusting the orientation and compensating detected aircraft orientation changes. The sidereal alignment is therefore not maintained.&lt;/p&gt;&#xA;&lt;p&gt;Most inertial systems cannot be realigned in motion, but they can be re-leveled, and while the north direction and the position cannot be recovered, the system is still be able to provide aircraft attitude (mode ATT).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/scxVE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/scxVE.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;The two IRS switches in the normal (navigation) position (&lt;a href=&quot;http://www.daviddarling.info/encyclopedia/L/latitude.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2021-05-05T14:28:47.960" LastActivityDate="2021-05-05T14:28:47.960" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="25656" PostTypeId="2" ParentId="25644" CreationDate="2016-02-27T22:02:13.337" Score="3" Body="&lt;p&gt;A &lt;em&gt;bulk strip&lt;/em&gt; may be an Australian term, e.g. &lt;a href=&quot;https://www.casa.gov.au/sites/g/files/net351/f/_assets/main/airworth/awb/85/005.pdf&quot; rel=&quot;nofollow&quot;&gt;this airworthiness bulletin&lt;/a&gt; and &lt;a href=&quot;http://www.bilyaragroup.com.au/EnginesMaintenance/BilyaraBlueSealEngines/EngineRepairsInspections/tabid/77/Default.aspx&quot; rel=&quot;nofollow&quot;&gt;this engine shop&lt;/a&gt;. I'd never heard of it before, but looking at those sites it seems to be something like a limited overhaul. The AB and the engine shop both list the steps and they're more or less the same: disassemble the engine, inspect all parts, replace any parts that need replacement, reassemble and test the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not an expert on maintenance by any means, but it looks to me like the difference between a bulk strip and a full overhaul is that the bulk strip is precautionary or diagnostic, as suggested by the machine shop site:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Not all engines need a full overhaul. You may have had a prop-strike,&#xA;  or your LAME may have identified metal in the filter or a crack in the&#xA;  crankcase. The pilot may have noticed unusual running of the engine.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;We can ‘bulk-strip’ your engine for a full diagnosis and provide you&#xA;  with a report of your engine’s health:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Looking at it another way, an overhaul &lt;em&gt;will&lt;/em&gt; replace a lot of parts whether they need it or not; a bulk strip &lt;em&gt;may&lt;/em&gt; replace parts if they're worn or broken.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-02-27T22:22:12.707" LastActivityDate="2016-02-27T22:22:12.707" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25658" PostTypeId="1" AcceptedAnswerId="25660" CreationDate="2016-02-28T05:30:43.203" Score="8" ViewCount="1038" Body="&lt;p&gt;I had assumed during a WAAS approach when the GPS is in LPV mode, both lateral guidance and vertical guidance are generated from GPS/WAAS signals and the pitot-static system should have no effect on its vertical guidance. This is in contrast with LNAV/VNAV approach, where the vertical guidance comes from the barometric system, the same source as altimeter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, when I read &lt;a href=&quot;http://flightaware.com/resources/airport/KHAF/IAP/RNAV+(GPS)+Z+RWY+30&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) Z RWY 30 @ KHAF&lt;/a&gt;, I will get a different DA if I use a different altimeter setting. So, why does altimeter settings matter to the DA in an LPV approach?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/S4nNX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S4nNX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-02-28T07:33:04.007" LastActivityDate="2017-02-26T04:25:47.120" Title="Does altimeter setting affect the vertical guidance in a LPV approach?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;gnss&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25659" PostTypeId="2" ParentId="16957" CreationDate="2016-02-28T06:48:22.993" Score="3" Body="&lt;p&gt;Once, all airliners were built as taildraggers. The most important reasons none are conventionally geared these days is simple. A taildragger has its center of gravity located behind the main wheels. Therefore, it is insanely easy to groundloop it. This is because taildraggers are not inherently directionally stable. This was not usually a problem when the pilot was ALWAYS expecting the tail to wander to either side on takeoff or landing roll. If a pilot got distracted or lazy and the tail wandered a bit too far  and he was late correcting with rudder, then the plane would swing around in a wild unstoppable loop and often dig in a wingtip, which was not only embarrassing but often damaged the plane. The tricycle gear stopped all that. The new nosegear planes went where the pilot pointed them and stayed there pretty much automatically. The center of gravity was now in front of the main gear and so the groundloop became a thing of the past. Conventional gear is lighter, and allows shorter takeoffs since the plane naturally sits tail low by design, but the instability issue means that its just a no brainer that large powerful airliners will never again&#xA;be designed with tailwheels...ever.&lt;/p&gt;&#xA;" OwnerUserId="13741" LastEditorUserId="50500" LastEditDate="2020-11-09T07:56:04.070" LastActivityDate="2020-11-09T07:56:04.070" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25660" PostTypeId="2" ParentId="25658" CreationDate="2016-02-28T07:36:20.397" Score="7" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;No, the vertical component of LPV approach performance is based on WAAS GPS input, not the altimeter or barometric system.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longer Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Your assumption about LPV performance is correct: Baro-VNAV is not used for LPV approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On any type of approach with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_approach#Decision_height_or_altitude&quot; rel=&quot;nofollow noreferrer&quot;&gt;Decision Altitude (DA)&lt;/a&gt;, the aircraft's arrival at the DA is determined by the pilot's reading of the aircraft's &lt;a href=&quot;https://aviation.stackexchange.com/a/16916/12720&quot;&gt;sensitive altimeter&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the altimeter is set to an altimeter setting report from a distant reporting station, SFO in this case, then the DA may be increased to give additional altitude margin to allow for variance in local atmospheric pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is true for the DA or &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_approach#Minimum_descent_altitude_.28MDA.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Minimum Descent Altitude (MDA)&lt;/a&gt; on any approach, whether a GPS approach or not. See the &lt;a href=&quot;https://skyvector.com/files/tpp/1602/pdf/05755IL33.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;MKT ILS 33&lt;/a&gt; and &lt;a href=&quot;https://skyvector.com/files/tpp/1602/pdf/05755R15.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;MKT RNAV 15&lt;/a&gt; for other examples of this. See the following excerpts from the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Manual&lt;/a&gt; on altimeter settings for approaches (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-4-5&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;a.&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;strong&gt;4.&lt;/strong&gt; Approach minimums are based on the local&#xA;  altimeter setting for that airport, unless annotated&#xA;  otherwise; e.g., Oklahoma City/Will Rogers World&#xA;  approaches are based on having a Will Rogers World&#xA;  altimeter setting. When a different altimeter source is&#xA;  required, or more than one source is authorized, it will&#xA;  be annotated on the approach chart; e.g., use Sidney&#xA;  altimeter setting, if not received, use Scottsbluff&#xA;  altimeter setting. &lt;strong&gt;&lt;em&gt;Approach minimums may be raised&#xA;  when a nonlocal altimeter source is authorized.&lt;/em&gt;&lt;/strong&gt; When&#xA;  more than one altimeter source is authorized, and the&#xA;  minima are different, they will be shown by separate&#xA;  lines in the approach minima box or a note; e.g., use&#xA;  Manhattan altimeter setting; when not available use&#xA;  Salina altimeter setting and increase all MDAs&#xA;  40 feet. When the altimeter must be obtained from a&#xA;  source other than air traffic a note will indicate the&#xA;  source; e.g., Obtain local altimeter setting on CTAF.&#xA;  When the altimeter setting(s) on which the approach&#xA;  is based is not available, the approach is not&#xA;  authorized. Baro−VNAV must be flown using the&#xA;  local altimeter setting only. Where no local altimeter&#xA;  is available, the LNAV/VNAV line will still be&#xA;  published for use by WAAS receivers with a note that&#xA;  Baro−VNAV is not authorized. When a local and at&#xA;  least one other altimeter setting source is authorized&#xA;  and the local altimeter is not available Baro−VNAV&#xA;  is not authorized; however, the LNAV/VNAV&#xA;  minima can still be used by WAAS receivers using the&#xA;  alternate altimeter setting source.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that Baro-VNAV is a type of VNAV system which uses barometric&#xA;altimetry as a basis for vertical navigation performance. An LNAV/VNAV approach can be flown using WAAS equipment without a Baro-VNAV system.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-02-28T22:29:44.973" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25661" PostTypeId="1" CreationDate="2016-02-28T11:08:48.523" Score="10" ViewCount="779" Body="&lt;p&gt;While turning from the 45˚ to the downwind leg for a downwind pattern landing in a Cessna 182, a Cheyenne was calling 5 miles out on a GPS approach for a straight in landing.  Clear day, both flying VFR, uncontrolled airport.  He and I had been communicating for 5-6 minutes, and I called my base turn knowing I had entered the pattern well ahead of him and had time to land ahead of him.  The Cheyenne pilot acknowledged me and was good with this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seconds before I touched down, I heard from a pilot evidently taxiing to take off from the same runway, &lt;strong&gt;&quot;Dude ... you just cut off that Cheyenne ... you realize he's going about 4 times faster than you.&quot;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now aside from his ignorance by not hearing the leadup conversation to our opposite direction approaches, when is a plane in a straight-on landing considered to have the right of way over one &quot;in the pattern&quot; and when, apart from communicating between pilots, is it proper regulation to land ahead, vs. extending the downwind leg and falling in behind him?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was specifically trained that until you are within 4 miles, you are technically not on &quot;final&quot; during a straight-in approach ... but that common sense must prevail, so even if you reach the pattern first, it may be courteous and safer to allow a faster aircraft in ahead of you.&lt;/p&gt;&#xA;" OwnerUserId="699" LastEditorUserId="699" LastEditDate="2016-03-01T05:15:31.480" LastActivityDate="2016-03-01T05:15:31.480" Title="Is it &quot;cutting off&quot; in the pattern when I go before a plane that is going faster than I am but let me in first?" Tags="&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25662" PostTypeId="2" ParentId="25661" CreationDate="2016-02-28T11:30:26.783" Score="9" Body="&lt;p&gt;The Cheyenne would have been &quot;cutting you off&quot;, if he hadn't worked it out with the aircraft in the pattern and maintained visual separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the AIM, 4-3-3, standard pattern entry at an uncontrolled airport is abeam the midpoint in the downwind. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Enter pattern in level flight, abeam the midpoint of the runway, at pattern altitude. (1,000’ AGL is recommended pattern altitude unless established otherwise. . .)&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faraim.org/aim/aim-4-03-14-189.html&quot;&gt;http://www.faraim.org/aim/aim-4-03-14-189.html&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12116" LastEditorUserId="12116" LastEditDate="2016-02-28T11:35:51.283" LastActivityDate="2016-02-28T11:35:51.283" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25663" PostTypeId="1" CreationDate="2016-02-28T11:47:32.207" Score="3" ViewCount="1000" Body="&lt;p&gt;What are the advantages of using electrical systems as a alternative to pneumatic systems in the Boeing 787-9? Is it a maintenance advantage?&lt;/p&gt;&#xA;" OwnerUserId="13748" LastEditorUserId="5517" LastEditDate="2016-02-29T17:29:39.020" LastActivityDate="2016-02-29T17:29:39.020" Title="What are the advantages of electrical systems over pneumatic systems?" Tags="&lt;aircraft-systems&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25664" PostTypeId="2" ParentId="25663" CreationDate="2016-02-28T12:14:49.367" Score="9" Body="&lt;p&gt;Just on example: The energy taken from the engine as bleed air is contained in this bleed air as heat and as pressure. Now pipe this energy to someplace where it is needed, and the air will cool down and lose some of its pressure. Also, if you want adequate insulation and low transmission losses, the cross section for the piping will be substantial.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare this to taking the energy from the engine by a driveshaft turning a generator: Friction losses will be a few percent at most, energy conversion in the generator will be at above 90%, and transmission losses are low again if your cable cross section is sufficient. Note that the cables will be much thinner than any bleed air line would ever be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add to this the advances made in converting electrical energy between different voltages and frequencies, and it becomes clear that modern aircraft systems can be made more efficient when run electrically. The use of compressed, hot air was only a better choice when modern power electronics were not yet around.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-28T22:35:01.547" LastActivityDate="2016-02-28T22:35:01.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25665" PostTypeId="1" AcceptedAnswerId="25674" CreationDate="2016-02-28T13:24:12.130" Score="4" ViewCount="1056" Body="&lt;p&gt;Almost every passenger cabin in a commercial aircraft is white with a little bit of grey. Why are they in these colors?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/iB2Cm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iB2Cm.jpg&quot; alt=&quot;Lufthansa737&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://ca.wikipedia.org/wiki/Avi%C3%B3_comercial#/media/File:Lufthansa_737_interior.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:07:09.033" LastActivityDate="2017-10-16T07:59:54.760" Title="Why are passenger cabins white?" Tags="&lt;aircraft-design&gt;&lt;passenger&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25667" PostTypeId="1" CreationDate="2016-02-28T16:55:39.990" Score="1" ViewCount="12838" Body="&lt;p&gt;What are the parameters considered and what formulas are used to find the Center of Gravity on an aircraft?&lt;/p&gt;&#xA;" OwnerUserId="5703" LastEditorUserId="12220" LastEditDate="2016-02-28T20:42:35.700" LastActivityDate="2018-09-16T09:53:58.480" Title="How do I determine the center of gravity on aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;aircraft-maintenance&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25668" PostTypeId="1" CreationDate="2016-02-28T17:54:52.633" Score="0" ViewCount="55" Body="&lt;p&gt;What is the significance of a V1 ground roll of an aircraft trying to take off? Why is minimum ground roll is measured in feet? What is the significance of VR (which is greater than V1 but less than V2)?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="12220" LastEditDate="2016-02-28T18:27:57.427" LastActivityDate="2016-02-28T18:27:57.427" Title="What is the significance of the V1 ground roll of an aircraft?" Tags="&lt;v-speeds&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-02-28T19:50:33.363" ContentLicense="CC BY-SA 3.0" />
  <row Id="25669" PostTypeId="1" CreationDate="2016-02-28T18:58:05.487" Score="0" ViewCount="120" Body="&lt;p&gt;Since the earth is rotating, why can't a plane that is flying from say, Perth to Johannesburg, just hover in the air and wait for Jo'burg to arrive underneath?&lt;/p&gt;&#xA;" OwnerUserId="13752" LastActivityDate="2016-02-28T18:58:05.487" Title="Why can't a plane flying due west just hover in the air and wait for the destination country to arrive?" Tags="&lt;general-aviation&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2016-02-28T19:49:21.407" ContentLicense="CC BY-SA 3.0" />
  <row Id="25670" PostTypeId="2" ParentId="25667" CreationDate="2016-02-28T20:28:19.857" Score="5" Body="&lt;p&gt;It is not fully clear to me whether you are interested in determining the CG (Center of Gravity) of a new design or an existing one, I guess is the latter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case the main parameters are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Payload (i.e.: people, cargo, other (e.g.: ammunitions))&lt;/li&gt;&#xA;&lt;li&gt;The Fuel&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The manufacturer provides you with tables to determine the CG due to the different loading condition (combination  of the aircraft payload and fuel).&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-02-28T22:19:02.867" LastActivityDate="2016-02-28T22:19:02.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25671" PostTypeId="2" ParentId="25667" CreationDate="2016-02-28T20:40:05.157" Score="7" Body="&lt;p&gt;You ask particularly about the Center of Gravity (CG), but not the weight. Any CG calculation will necessarily include the weight as a component of the calculation; therefore I refer to the calculations as weight and balance (or CG) calculations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two primary ways that weight and balance measurements are determined are by physically weighing the aircraft and by mathematically calculating based on additions or subtractions to the previous weight. The former is performed by maintenance personnel and forms the empty weight and CG for any given aircraft. The later may be performed by either flight operators or by maintenance and uses the predetermined empty weight and CG as the basis for the calculations; this may be needed due to the installation of new equipment, for example, or a pilot may do such a calculation to determine the weight and CG for a given flight with, for example, fuel and passengers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For maintenance operations, most aircraft have a section in the maintenance manual or operating handbook that prescribes the process. For flight operations, most aircraft have an information manual or operating handbook that will prescribe the calculation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One necessary parameter is an established &lt;a href=&quot;https://en.wikipedia.org/wiki/Center_of_gravity_of_an_aircraft#Terminology&quot; rel=&quot;nofollow&quot;&gt;reference datum&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The basic formula is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;C_G=\frac{(W_1\cdot A_1)+(W_2\cdot A_2)}{W_1+W_2}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$W_n$ is the weight of the aircraft scale's measurement, predetermined empty weight, fuel, or payload, etc.&lt;/li&gt;&#xA;&lt;li&gt;$A_n$ is the moment arm, in reference to the datum, of the of the aircraft scale's measurement, predetermined empty CG, fuel, or payload, etc.&lt;/li&gt;&#xA;&lt;li&gt;$C_G$ is the solution to the center of gravity for the aircraft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The cancelled FAA Advisory Circular &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/74451&quot; rel=&quot;nofollow&quot;&gt;AC65-9A&lt;/a&gt; contains an entire chapter (&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2065-9A/$FILE/Chapter%203.pdf&quot; rel=&quot;nofollow&quot;&gt;Chapter 3&lt;/a&gt;) dedicated to the subject of weight and balance, including exactly what you ask, the parameters that must be considered and the formulae used to perform the calculations. Though cancelled, the AC is still available online (I have a print copy).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;EDIT: See the comment below from @voretaq7 referencing the excellent &quot;Aircraft Weight &amp;amp; Balance Handbook&quot; quoted here:&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In addition to AC 65-9A the current Aircraft Weight &amp;amp; Balance Handbook&#xA;  &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/&quot; rel=&quot;nofollow&quot;&gt;(FAA-H-8083-1A - available here)&lt;/a&gt; contains more than you ever wanted to&#xA;  know about computing weight &amp;amp; balance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/media/FAA-H-8083-1A.pdf&quot; rel=&quot;nofollow&quot;&gt;This is currently the direct link&lt;/a&gt; to the PDF of that document.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-02-29T21:06:48.997" LastActivityDate="2016-02-29T21:06:48.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25673" PostTypeId="2" ParentId="25261" CreationDate="2016-02-28T21:19:03.437" Score="5" Body="&lt;p&gt;The Maximum Zero Fuel Weight Payload, is the amount of payload $m_{pl}$ (i.e.: passengers, cargo, but &lt;em&gt;not&lt;/em&gt; fuel) required to reach the  Maximum Zero Fuel Weight condition while keeping the fuel weight, $m_{fuel}$ to zeros so:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ &#xA;while \; m_{fuel} =0: \\&#xA;MZFW = OEW + m_{pl} \\&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Maximum Zero Fuel Weight ($MZFW$) is an indicator of the maximum loads that the wing structure can bear. For the wing an &quot;unloaded&quot; situation (no fuel in the wing) is critical, since the fuel stored in the wing helps reducing the loads on it in flight. The lift acts &quot;upward&quot; while fuel weight acts &quot;downward&quot;, thus the fuel contribution helps &lt;em&gt;relieving&lt;/em&gt; loads from the wing structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The volume limited payload is an indicator for the sizing of the cargo compartment structures. These are the structures of the cargo area, where the &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;noreferrer&quot;&gt;LD&lt;/a&gt; containers are stored (under the floor of the passenger cabin). This Volume Limited Payload is set to avoid having too &quot;dense&quot; LD containers, the limit of density for the containers is around 350 $kg/m^3$, you can find some technical specifications for LD container &lt;a href=&quot;https://www.deltacargo.com/ShippingToolsInformation/ShippingContainersGuidelines.aspx&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-02-28T22:49:00.957" LastActivityDate="2016-02-28T22:49:00.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25674" PostTypeId="2" ParentId="25665" CreationDate="2016-02-28T22:50:11.757" Score="12" Body="&lt;p&gt;The picture in your question shows the answer: Most lighting in the cabin is done indirectly, so you don't see the light source directly. Instead, light is reflected off the cabin interior. If you would paint that interior in gaudy colors, you would have undesirable effects. Colored surfaces absorb some wavelengths, so the brightness in the cabin is reduced. Plus, the selective reflection will shift the color of the light.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Newspaper and magazine paper would not be white anymore, but have the color of the cabin interior. As @mins correctly points out, the brain can compensate for this. It will, however, make it difficult to read text printed in the color of the cabin interior because it would no longer stand out from the background.&lt;/li&gt;&#xA;&lt;li&gt;The color pictures in the magazines would look funny. If you now think people could switch on the reading lights: Note how few passengers actually know how to operate them.&lt;/li&gt;&#xA;&lt;li&gt;The food you get served would look funny. It is already not a pleasure to look at in most cases, but in colored light it gets even worse.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;While it might be fun momentarily to be in a room with mood lighting, being exposed to this one color for the full length of the flight without a possibility to escape (except for closing your eyes) will offend most passengers.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-02-29T14:23:17.233" LastActivityDate="2016-02-29T14:23:17.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25675" PostTypeId="2" ParentId="25665" CreationDate="2016-02-28T23:04:22.563" Score="5" Body="&lt;p&gt;Although not the original reason, modern plane interiors are designed to keep people calm. &lt;a href=&quot;http://boeing.mediaroom.com/2002-03-08-The-Psychology-of-Comfort-in-Airplane-Interior-Design&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing has a nice article on it here&lt;/a&gt; that is worth taking a look at. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Color psychology plays an important role in developing the overall&#xA;  look. Studies show that people in different cultures associate certain&#xA;  colors with similar emotions or concepts. Blue/green is nearly&#xA;  unanimously associated with peace. Pink and lavender shades connote&#xA;  love, while blue/purple may signify nobility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The darker colors of seats can also aid in hiding stains and dirt better than say white or tan leather (which is found in a lot of GA planes). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As has also be mentioned in some of the comments white plastic is how most plastics are made thus its most likely cheaper to order something in white than have it colored. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some emergency implications to interior colors. In the case of an emergency you want the exits to be clearly marked and easy to find. If you have a &quot;busy&quot; interior when it comes to both over all design and color you can have issues making an emergency exit that contrasts well enough to see when it needs to be seen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what it's worth color has been tried (then again, it was the 70s). Now think about a red emergency light going off in this plane, it would barely stand out. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/vHig0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vHig0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.wists.com/thumbnails/c/5c/c5c6de1d98f5e4b611c7be17fbfb4b82-orig&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="938" LastEditDate="2016-03-06T01:08:50.790" LastActivityDate="2016-03-06T01:08:50.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25676" PostTypeId="1" AcceptedAnswerId="25707" CreationDate="2016-02-28T23:11:44.343" Score="17" ViewCount="5521" Body="&lt;p&gt;From my understanding, a gyroplane (autogyro):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Rotorcraft&quot; rel=&quot;noreferrer&quot;&gt;rotocraft&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Uses an unpowered rotor for lift generation, instead of wings.&lt;/li&gt;&#xA;&lt;li&gt;Uses a propeller for horizontal translation like an airplane.&lt;/li&gt;&#xA;&lt;li&gt;Cannot take off vertically or hover contrary to an helicopter.&lt;/li&gt;&#xA;&lt;li&gt;Can land vertically like an helicopter using rotor inertia.&lt;/li&gt;&#xA;&lt;li&gt;Maybe simpler to build and maintain than an helicopter or an airplane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/znggj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/znggj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are gyroplanes a technology that works but without particular application? Or do gyroplanes have well known uses for which they have significant advantages over airplanes and helicopters?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="19" LastEditDate="2016-07-05T11:16:26.737" LastActivityDate="2017-05-28T07:29:28.417" Title="What are the uses of gyroplanes?" Tags="&lt;rotorcraft&gt;&lt;autogyro&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25677" PostTypeId="2" ParentId="25569" CreationDate="2016-02-28T23:15:43.403" Score="5" Body="&lt;p&gt;Thank you for your question, I never &quot;realised&quot; that even most &quot;exotic&quot; airplane have a maximum ceiling height of not more than 30 km (stratosphere). Why should that be?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Starting from &lt;em&gt;very&lt;/em&gt; first principle, a force shall balance gravity, in &quot;conventional&quot; aircraft, lift equal weight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ W = \frac{1}{2} \rho S V^2 Cl $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's have a look at what happens to density ($\rho$) for height above 30 km, it goes almost to zero! So above this &quot;threshold&quot; it is more convenient to use other principles to contrast gravity, buoyancy, like baloons, or a force directed vertically, similarly to missiles and thurst!&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rPg4B.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rPg4B.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-02-29T16:15:24.457" LastActivityDate="2016-02-29T16:15:24.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25678" PostTypeId="2" ParentId="25641" CreationDate="2016-02-28T23:41:08.243" Score="3" Body="&lt;p&gt;&lt;em&gt;resome own navigation&lt;/em&gt; means any navigation instructions are no longer in effect and you may fly as you wish.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an altitude restriction has been given, you must maintain that restriction until you hear &quot;altitude your discretion.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If no altitude restriction had been given then you may of course change your altitude.  &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-02-28T23:41:08.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25679" PostTypeId="2" ParentId="25529" CreationDate="2016-02-29T00:42:49.423" Score="4" Body="&lt;p&gt;Lets consider the dihedral angle from three points of view:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Stability, the more conventional one, it mainly influences spiral stability, which is the tendency of the aircraft to enter into a spiral due to a perturbation (i.e.: gust): The aircraft should not enter this spiral, it is allowed to enter in a spiral only when the motion  is slow enough for the pilot to safely recover. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Reduction of induced drag, a more &quot;unconventional&quot; aspect to analyse the dihedral angle, requires higher dihedral angles. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Integration, keeping  clearance between the ground and the wing tip and/or engines/propellers. This is specially important for the ground phases.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From the stability point of view the dihedral main effect is on the &lt;span class=&quot;math-container&quot;&gt;$C_{l_{\beta}}$&lt;/span&gt; (and &lt;span class=&quot;math-container&quot;&gt;$C_{l_{r}}$&lt;/span&gt;) derivative. This derivative plays a major role (along with other such as (&lt;span class=&quot;math-container&quot;&gt;$C_{n_{r}}$&lt;/span&gt; &lt;span class=&quot;math-container&quot;&gt;$C_{l_{p}}$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$C_{n_{p}}$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$C_{n_{r}}$&lt;/span&gt;) in defining the spiral and dutch-roll modes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These other derivatives usually depends heavily on the design of the vertical stabilizer design (except &lt;span class=&quot;math-container&quot;&gt;$C_{l_{p}}$&lt;/span&gt;, which is mainly influenced by aspect ratio). Since the vertical stabiliser design is more complex than trading the dihedral angle (whose main influence is on &lt;span class=&quot;math-container&quot;&gt;$C_{l_{\beta}}$&lt;/span&gt;) , the latter can be used to &quot;&lt;em&gt;adjust&lt;/em&gt;&quot; the desired spiral and dutch-roll modes, to desired values. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dihedral angle, when exaggerated, has a secondary effect on induced drag as well. This can be seen from the configuration on the bottom right in the figure below. Here it can be noted how a  (&lt;em&gt;very&lt;/em&gt;) high dihedral angle has a positive effect on the aerodyanmic efficiency factor &lt;span class=&quot;math-container&quot;&gt;$\epsilon$&lt;/span&gt;. Generalizing, the higher the displacement of the wing (the dihedral angle) the better it is for induced drag (think about the new B787 or A350 designs). Since induced drag is the main component of drag in low speed, and since the aircraft you mentioned (solar impulse, kinetiq zephir), are solar powered and flying slowly I can imagine that they have a &lt;em&gt;stronger&lt;/em&gt; use case to minimize drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally the dihedral angle can be used to mitigate &quot;integration&quot; problems. The other example you mentioned I think fall in this category. On the Beriev Be 12,the propellers would be too close to the water, expecially when the aircraft is floating (see &lt;a href=&quot;https://www.airliners.net/photo/Beriev-Design-Bureau/Beriev-Be-12P-200-Chaika/1391168/L?sid=f0cbec0afe809c3a6ea247b19f68f5f1&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;). And similar the Habicht wihtout the gull wing would have a wing tip too close to the ground. &#xA;  &lt;a href=&quot;https://web.archive.org/web/20170830224622/https://upload.wikimedia.org/wikipedia/en/e/ef/Inducd_drag_minimization.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://web.archive.org/web/20170830224622/https://upload.wikimedia.org/wikipedia/en/e/ef/Inducd_drag_minimization.jpg&quot; alt=&quot;Minimize Indiced Drag&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="8282" LastEditDate="2019-07-19T19:00:48.437" LastActivityDate="2019-07-19T19:00:48.437" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="25680" PostTypeId="1" CreationDate="2016-02-29T01:42:07.023" Score="5" ViewCount="2215" Body="&lt;p&gt;How do aircraft like the V-22 not tilt under an unbalanced load? if they are only supported by 2 forces on either side a large weight in the back should cause it to lean backward when stationary, should it not? its hard to put this into an image but here goes nothing:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EJoEZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EJoEZ.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;A large weight in the back would surely cause it to lean; &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:MV-22_Osprey_Line_Drawing.svg&quot; rel=&quot;nofollow noreferrer&quot;&gt;original image source&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13759" LastEditorUserId="14897" LastEditDate="2021-03-13T14:46:41.657" LastActivityDate="2021-03-13T14:46:41.657" Title="How do VTOL aircraft like the V-22 Osprey not tilt?" Tags="&lt;aircraft-design&gt;&lt;weight-and-balance&gt;&lt;tiltrotor&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="25681" PostTypeId="1" CreationDate="2016-02-29T04:17:44.863" Score="2" ViewCount="1081" Body="&lt;p&gt;I came across this video few days back on Edx 16.101 youtube channel. &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/byqqRZBq3FI?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&#xA;At 7.00 min of the video, the presenter derived an equation for minimum flight power which does not depend on Cd0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$P_\min = \frac{4}{3\pi e AR}  \sqrt{\frac{2W^3CL}{\rho S}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have a doubt on the derivation, but this result seems to be very contradictory for me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, let's take 2 identical aircrafts, one with fuselage airbrakes deployed and one without. (Identical CL, AR, $\rho$, S, CL and e but different Cd0)&#xA;According to this expression the power requered cannot change. But,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;For same CL, V is going to be the same&lt;/li&gt;&#xA;&lt;li&gt;With airbrakes deployed, aircraft 1 drag is much higher than the aircraft 2&lt;/li&gt;&#xA;&lt;li&gt;Power required (D*V) should be higher for aircraft 1.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;May be I am missing something simple. Why is this apparent contradiction?&lt;/p&gt;&#xA;" OwnerUserId="13760" LastEditorDisplayName="user5664" LastEditDate="2016-10-01T20:47:24.510" LastActivityDate="2016-10-01T20:47:24.510" Title="Does the minimum power required for level flight depend on CD0?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25682" PostTypeId="1" CreationDate="2016-02-29T07:15:31.773" Score="0" ViewCount="71" Body="&lt;p&gt;Normally one would expect that if the pitch angle is zero, that is the aircraft is level on the artificial horizon, how would the wing present itself to the relative wind at such high angle that it exceeds the critical AOA.?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2016-02-29T07:15:31.773" Title="How can critical angle of attack of the wing of an an aircraft exceed even when the pitch angle is zero?" Tags="&lt;stall&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-02-29T14:34:33.663" ContentLicense="CC BY-SA 3.0" />
  <row Id="25683" PostTypeId="1" CreationDate="2016-02-29T07:55:45.310" Score="0" ViewCount="819" Body="&lt;p&gt;Is it possible for an airplane to fly as it compress the atmospheric air during flight?&lt;/p&gt;&#xA;" OwnerUserId="13761" LastEditorUserId="13761" LastEditDate="2016-02-29T17:35:19.890" LastActivityDate="2016-02-29T17:35:19.890" Title="Is it possible for an airplane to produce thrust from compress air without using fuel?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2016-02-29T14:34:50.427" ContentLicense="CC BY-SA 3.0" />
  <row Id="25684" PostTypeId="2" ParentId="25683" CreationDate="2016-02-29T11:09:04.577" Score="5" Body="&lt;p&gt;First of all, where does the compressed air come from? Is it stored in big tanks, or do you compress it as you fly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you use the second way (the first would be quite inefficient), you need to power the Air Compressor, which means you need to generate energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do not want to use fuel, then it has to be powered by electricity, i.e. an electric plane. This is basically how the Airbus &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_E-Fan&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-Fan&lt;/a&gt; works, using two ducted fans powered by electricity (as &lt;a href=&quot;https://aviation.stackexchange.com/users/5568/zach-lipton&quot;&gt;@Zach Lipton&lt;/a&gt; said in the comments)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question, yes, your theory works. There are already a few prototypes using it.&lt;/p&gt;&#xA;" OwnerUserId="13540" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-02-29T11:09:04.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25685" PostTypeId="1" CreationDate="2016-02-29T13:12:15.617" Score="39" ViewCount="13394" Body="&lt;p&gt;The phrase &quot;aviate, navigate, communicate&quot; is commonplace among pilots, as a reminder to concentrate on flying the aircraft first, with navigation a secondary focus, and fitting in communication when it won't interfere with those other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military pilots have other things to distract them from the primary focus on flying: tracking the target they want, keeping an eye out for other threats (not just collision threats), managing EM emitters or countermeasures, &amp;amp;c. Flying into a bad situation due to &quot;target fixation&quot; is not uncommon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do military pilots have any kind of drill, phrase, mnemonic, or teaching aid to set priorities for their flying, like &quot;aviate, navigate, communicate&quot;? To be clear, I expect they use that phrase for 'normal' flying, and I'm curious to know if there's an extra mnemonic about their combat-specific priorities; maybe something like &quot;wingman, threats, targets&quot;.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2016-02-29T15:22:35.057" LastActivityDate="2020-08-12T23:54:23.290" Title="Do military pilots have a phrase like &quot;aviate, navigate, communicate&quot;?" Tags="&lt;military&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25686" PostTypeId="2" ParentId="25685" CreationDate="2016-02-29T14:02:20.027" Score="79" Body="&lt;p&gt;I am a Naval Aviator and have commanded a flight training squadron.  We actually teach that very phrase.  Aviate, navigate, communicate was one of the first things I learned, and it has served me well over the years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It applies no matter the situation.  The target fixation example you gave is a good one.  Getting an aircraft where it needs to be to put a bomb on target is clearly in the navigate realm.  It is superseded by not flying into the ground...which is in the aviate realm.  &lt;/p&gt;&#xA;" OwnerUserId="8210" LastActivityDate="2016-02-29T14:02:20.027" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25687" PostTypeId="2" ParentId="25685" CreationDate="2016-02-29T15:00:11.297" Score="42" Body="&lt;p&gt;I am a former USMC helicopter pilot and after 20 years I still remember that very phrase - and used it to teach my kids to drive. Yes, it &lt;em&gt;is&lt;/em&gt; a phrase used by military pilots and, given its value, I am sure it is used by pilots in general. The general concept is &quot;don't fly into something or fly into a situation where your wings/rotors get ripped off because you were trying to talk to someone or figure out where you are as opposed to where you are supposed to be.&quot; If you aren't flying the bird, nothing else matters. If you are flying the bird but don't know where you are/are going, then nothing you can tell others matters.&lt;/p&gt;&#xA;" OwnerUserId="13763" LastActivityDate="2016-02-29T15:00:11.297" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25689" PostTypeId="2" ParentId="25661" CreationDate="2016-02-29T15:32:13.543" Score="4" Body="&lt;p&gt;Since you and the Cheyenne pilot had it worked out you are ok and you made a proper entrance to the pattern. However its worth mentioning that there is at least one right of way rule that could apply here (depending on the situation). &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/934f0a02e17e7de086256eeb005192fc!OpenDocument&quot; rel=&quot;nofollow&quot;&gt;Sec. 91.113&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(g) Landing. Aircraft, while on final approach to land or while&#xA;  landing, have the right-of-way over other aircraft in flight or&#xA;  operating on the surface, except that they shall not take advantage of&#xA;  this rule to force an aircraft off the runway surface which has&#xA;  already landed and is attempting to make way for an aircraft on final&#xA;  approach. When two or more aircraft are approaching an airport for the&#xA;  purpose of landing, the aircraft at the lower altitude has the&#xA;  right-of-way, but it shall not take advantage of this rule to cut in&#xA;  front of another which is on final approach to land or to overtake&#xA;  that aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the situation were that the Cheyenne was at say 2,000 ft on his final approach (even 5 miles out) and you overflew the field at 2,500 and made a teardrop entrance to the 45 descending 1000ft. in the process (putting you at 1,500ft. (lets call this pattern altitude)). You would in turn potentially be in breach of 91.113 since you cut in beneath him. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/awp/media/education/safety%20advisor%20non-towered%20airports.pdf&quot; rel=&quot;nofollow&quot;&gt;this brief on un-towered operations&lt;/a&gt; the FAA states that it is common courtesy to extend your downwind leg in this situation &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Courtesy Tip&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If another aircraft is on a straight-in instrument&#xA;  approach in visual conditions and it will not greatly inconvenience&#xA;  you, consider extending your downwind and announce your intentions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;With that in mind, there is no hard rule about it so you are in the clear, the extension is a courtesy to the other aircraft and intended mostly for safety reasons.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a slight tangent, at a towered airport its likely your downwind leg would have been extended by the controller (which is where the courtesy tip most likely stems from) to allow the Cheyenne to come in. If the guy on the ground flys out of towered fields a lot he may be accustom to this style of operations and assumed a rule was broken. This happened to me while on my downwind at a towered airport, a little beech jet entered on the ILS and my downwind was extended to allow him in. That plane was so fast he was on the ground and at the FBO before I turned base.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-02-29T15:32:13.543" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25690" PostTypeId="1" CreationDate="2016-02-29T16:13:38.637" Score="-4" ViewCount="369" Body="&lt;p&gt;I recently ordered the book &quot;The Killing Zone&quot; and am looking forward to reading it. Most of the reviews were positive, but one reader complained that the author made the mistake of using accident frequency counts, rather than accident rates. What is he talking about?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;MAIN QUESTION: Are the statistics in “The Killing Zone” appropriate and scientifically correct?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would seem to me that the natural statistics would be fatal accidents per flight hour. Does the book not use this measure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have read elsewhere that the highest accident rates are those involving pilots having between about 200 hours and 800 hours. Does that come from this book?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly enough, my personal experience with fatal accidents does not correspond with this. Every one of the 8 or so pilots I have known (indirectly in all cases) that have been killed in an accident were high time pilots (&gt; 1500 hours). &lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-02-29T17:30:33.043" LastActivityDate="2016-02-29T18:11:43.670" Title="Are the statistics in &quot;The Killing Zone&quot; appropriate and scientifically correct?" Tags="&lt;accidents&gt;&lt;books&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2016-02-29T19:34:13.373" ContentLicense="CC BY-SA 3.0" />
  <row Id="25691" PostTypeId="1" CreationDate="2016-02-29T16:20:43.757" Score="6" ViewCount="2081" Body="&lt;p&gt;I'm looking at a Mooney M20C with a pretty dated panel, but it's airworthy and could be a great opportunity to build some retrac time. The KLN89b GPS is IFR Certified, but is positively ancient. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There seems to be a convoluted process to keep it up to date. I don't know if the present owner has the cable or the proprietary card reader. I've found &lt;a href=&quot;http://www.ebay.com/itm/Bendix-King-KLN-94-GPS-Data-Card-Reader-Updater-SanDisk-ImageMate-SDDR-31/221573660073&quot; rel=&quot;noreferrer&quot;&gt;some on eBay&lt;/a&gt; that seem to be for the KLN94 so I'm not sure if they will work with the KLN89b. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my club we have a C172 with a GNS430 that has a fairly straightforward update process. I'm hoping the KLN89b is pretty similar if I get the card reader. I certainly don't want to take the entire GPS out of the aircraft and load it into a docking station every month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anyone can share their experience with this unit that would be great.&lt;/p&gt;&#xA;" OwnerUserId="13765" LastEditorUserId="1696" LastEditDate="2016-02-29T16:31:41.047" LastActivityDate="2019-12-08T06:39:29.983" Title="How can I keep the data on a KLN89b GPS up to date?" Tags="&lt;gnss&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25692" PostTypeId="1" AcceptedAnswerId="25700" CreationDate="2016-02-29T16:42:21.967" Score="-5" ViewCount="845" Body="&lt;p&gt;One episode I remember well from my training was a lesson on engine failure. To this day I am still a little uncertain about the takeaway from that lesson, which was by a secondary instructor, not my main instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happened is that we were cruising along around 3000 feet AGL and he reaches over and closes the throttle, putting the engine on idle: &quot;You have an engine failure and cannot restart it, what are you going to do?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I scan the landscape in front of me and see a muddy pond with a road next to it. From my glider experience I know I can land the plane in 50-100 feet on the bank of that pond and it will be an easy landout because the road is right there. So, I make for the pond.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The instructor says, &quot;No, no, do a 360&quot;. So, I do a 360 and lo and behold there is a small 2500-foot private airstrip right behind me. What a coincidence. I line up and deadstick onto the airstrip. He opens the throttle before I touch down and the lesson is over.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in that situation I had a place I knew I could land OR I could do a 360 and look for an even better place at the cost of losing altitude. Doing a 1-minute turn at -500 feet/minute, the altitude penalty for doing the 360 is probably going to be between 500 and 800 feet (out of my 3000). Is it the right policy to do the 360 or go for the first landable location you see as I had done originally?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="64" LastEditDate="2016-03-01T06:21:45.553" LastActivityDate="2018-04-10T18:15:43.310" Title="Do a full 360 on engine failure?" Tags="&lt;emergency&gt;&lt;engine-failure&gt;&lt;emergency-procedures&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="1" ClosedDate="2016-02-29T20:12:20.167" ContentLicense="CC BY-SA 3.0" />
  <row Id="25693" PostTypeId="2" ParentId="25692" CreationDate="2016-02-29T17:09:23.377" Score="12" Body="&lt;p&gt;The lesson here is not about the 360 but about locational awareness (the airstrip being there was no coincidence). One of the best quotes I have ever heard from an old pilot is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;A flight is not from point A to point B as much as its a series of&#xA;  hops from one potential landing spot to another&quot;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;-- An Old Pilot &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The take away is that your instructor was checking to see if you knew where you were and thus knew there was an airfield behind you (and subsequently out of sight). In your case there is nothing incorrect about picking a field and heading for it. If you have sufficient altitude and no suitable field is found a 360 is not a bad choice to check for a field. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On another note, a pond is not a suitable field for landing for a variety of reasons. First off you were (presumably) in a fixed gear plane. While belly landing a retract on water can be preformed safely, belly landing a fixed gear plane on water can be dangerous since the wheels will create a lot of drag when they hit the water. &lt;a href=&quot;http://generalaviationnews.com/2016/02/29/continued-flight-into-imc-ends-in-field/&quot;&gt;Mud can also be dangerous&lt;/a&gt; as you wont really roll on it as much as you will sink hard into it, and potentially nose over. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-02-29T17:09:23.377" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25694" PostTypeId="2" ParentId="2065" CreationDate="2016-02-29T17:56:58.057" Score="1" Body="&lt;p&gt;Balked Landing – A discontinued landing attempt. Term is often used in conjunction with aircraft configuration or performance assessment, as in “Balked landing climb gradient”. Also referred to as  “Go-Around”&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-02-29T17:56:58.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25695" PostTypeId="1" CreationDate="2016-02-29T18:01:27.813" Score="2" ViewCount="12022" Body="&lt;p&gt;Is there a difference between overrun and overshoot landings or are they exactly the same, talking about a runway excursion?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastEditorUserId="22726" LastEditDate="2019-02-22T04:29:43.807" LastActivityDate="2020-03-03T19:52:32.503" Title="What's the difference between overrun and overshoot landings?" Tags="&lt;runways&gt;&lt;runway-overrun&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25696" PostTypeId="2" ParentId="25690" CreationDate="2016-02-29T18:11:43.670" Score="1" Body="&lt;p&gt;I did a bit of reading and found the review questioning the book. That review was written by William R. Knecht.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Knecht has provided in that review a &lt;a href=&quot;http://www.sciencedirect.com/science/article/pii/S0001457513003242&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt; to one of his papers. (Payment is required but the abstract is free to read anyway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead a bit of searching led me to &lt;a href=&quot;https://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/2010s/media/201503.pdf&quot; rel=&quot;nofollow&quot;&gt;this paper&lt;/a&gt; also by William Knecht which I believe covers similar material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;His argument requires a lot of specialist statistical knowledge to understand, but it is worth a read through, especially the Introduction and the Discussion sections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are huge numbers of low-hours pilots, and their accident counts swamp the true pattern of data (my interpretation).  The high-hours pilots have &lt;strong&gt;some&lt;/strong&gt; accidents too, but the data there is noisy due to the relatively low number of these pilots. (Poor data sources are mentioned too.  See the paragraph beginning &quot;We end with an appeal to the FAA and NTSB.&quot;) A more sophisticated analysis of this noisy data would seem to suggest that the &quot;Killing zone&quot; is much wider, reaching up to pilots with a few thousand hours, maybe more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disclaimer: we would probably need to be professional statisticians to understand every detail of the argument. Everything I've written above is my own interpretation, as a non-specialist.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2016-02-29T18:11:43.670" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25697" PostTypeId="1" AcceptedAnswerId="27073" CreationDate="2016-02-29T18:12:07.350" Score="14" ViewCount="820" Body="&lt;p&gt;If improper loading leads to a tip up on a tricycle-geared aircraft:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lBtQQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lBtQQ.jpg&quot; alt=&quot;http://www.iasa-intl.com/folders/belfast/Gemini_tipup/GeminiMD11-Dubai.jpg&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.iasa-intl.com/folders/belfast/Gemini_tipup/GeminiMD11-Dubai.jpg&quot; rel=&quot;noreferrer&quot;&gt;Image source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;what methods are used to &lt;strike&gt;right&lt;/strike&gt; level the aircraft?&lt;/p&gt;&#xA;&lt;p&gt;I can imagine inflating airbags under the tail, or lifting it with a crane, but what prevents it from slamming down on the nose gear once it passes the tipping point?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-02-15T08:47:40.213" Title="How would a tricycle-geared aircraft be recovered from a tip-up?" Tags="&lt;accidents&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25698" PostTypeId="2" ParentId="25695" CreationDate="2016-02-29T18:21:51.397" Score="5" Body="&lt;p&gt;They are more or less the same and are often used interchangeably. &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAdvisoryCircular.nsf/list/AC%2091-79/$FILE/AC_91_79.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA AC 91-79 Runway Overrun Prevention&lt;/a&gt; defines runway overrun as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A runway overrun event is a departure of the aircraft from the end of the intended landing runway surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It means that the aircraft has touched down on the runway before going off it. Overshoot is used in the same sense (note that overrun/overshoot occurs both in TO/landing).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there is one case where they are used differently. Overshooting the runway also can mean that the aircraft has touched beyond the end of the runway i.e. missed the runway entirely.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-02-29T18:21:51.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25699" PostTypeId="1" AcceptedAnswerId="25701" CreationDate="2016-02-29T18:30:09.637" Score="7" ViewCount="1441" Body="&lt;p&gt;Why don't they have yaw dampers if they are always &quot;suffering&quot; from adverse yaw?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="21091" LastEditDate="2019-08-14T14:16:36.887" LastActivityDate="2019-08-14T17:46:55.323" Title="Why don't all GA aircraft have yaw dampers?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;flight-controls&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25700" PostTypeId="2" ParentId="25692" CreationDate="2016-02-29T18:59:26.760" Score="5" Body="&lt;p&gt;Unconditionally, &lt;strong&gt;NO&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The principle is that you should prefer worse result you can certainly achieve over better result you can possibly achieve. You had a landing spot where you could make a survivable landing. That is good enough. Look for anything else &lt;em&gt;only if&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;You actually noticed your flew over a small airstrip. I would expect the instructor to hint that they actually expected you to notice it though if he expected it¹.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The original landing spot is close enough that you can make a 360 &lt;em&gt;and still make that spot if you find nothing else&lt;/em&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But by all means, you must never ever give up a spot for survivable emergency landing spot unless you see a spot that provides safer landing &lt;em&gt;at is at least as certainly reachable&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ I do think it was the original point of the lesson, but I can imagine the instructor themselves didn't really get it when they learned it and therefore reproduced it poorly.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2018-04-10T18:15:43.310" LastActivityDate="2018-04-10T18:15:43.310" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25701" PostTypeId="2" ParentId="25699" CreationDate="2016-02-29T19:02:21.240" Score="17" Body="&lt;p&gt;A yaw damper means added cost, weight, complexity, and one more system that has to be maintained. That's the downside. The upside, for most GA aircraft is that they relieve the pilot of having to make a &quot;coordinated&quot; turn. In other words, having to apply appropriate rudder input along with aileron input. Is that convenience worth the downside when the pilot has internalized doing that without having to think about it? That's a matter of opinion. For myself, a yaw damper in any of the, say, single engine Cessnas would be a waste.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some GA aircraft that could benefit from a yaw damper in other than banking into a turn or leveling from a turn. For example, in level flight the old V-tail Bonanza would yaw around the vertical axis in turbulence to an objectionable degree in my opinion. Very uncomfortable, especially to passengers in the back seat. It would have been great to have had a yaw damper.&lt;/p&gt;&#xA;" OwnerUserId="394" LastActivityDate="2016-02-29T19:02:21.240" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25702" PostTypeId="2" ParentId="25692" CreationDate="2016-02-29T19:24:51.507" Score="4" Body="&lt;p&gt;&lt;strong&gt;&lt;em&gt;Is doing a 360 a normal part of engine out procedures?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, you should not even really be asking such a question here.&#xA;For emergency procedures, you probably want to check the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/&quot; rel=&quot;nofollow&quot;&gt;FAA Handbooks&lt;/a&gt;, or other training materials.  Your POH will detail procedures, and your instructor is a reliable source of info.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that you did ask here:  &lt;strong&gt;No, doing a 360 is not an advisable emergency maneuver, especially at 3,000 AGL&lt;/strong&gt;.  (You may be able to make an argument that the altitude loss is worth the value at much higher altitudes.  But 3,000 is pretty low).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Why did my instructor ask me to do a 360?&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He was encouraging you to locate an ideal landing spot that you already should have been aware of.  Although he kept you busy, situational awareness, both with respect to the ground and other VFR aircraft, is a non-negotiable item.  You cannot skip it when you're &quot;busy&quot;.  Spotting a 2,500 airstrip from 3,000 AGL should've been a no-brainer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm confident that he was not instructing you in &quot;normal&quot; procedures when he told you to do a 360.  He probably should have made that clear, both at that time and during the after-flight de-brief.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;But I had a good landing spot picked out&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think you'll find many people who like your description of &lt;em&gt;&quot;a muddy pond with a road next to it&quot;&lt;/em&gt; as a good landing spot, despite what Alaskan Bush Pilots are capable of.   (Note that most bush pilots will make &lt;em&gt;several&lt;/em&gt; passes over a landing spot before finally touching down.  You don't have that luxury with an engine out.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you imagine an NTSB report that says the pilot died after chosing a muddy pond when a perfect airstrip was less than 2 miles away?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You did not have a good landing spot picked out, and you may recall that over-confidence in one's own abilities is a major risk factor contributing to accidents.  Please dwell on that for some time.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-02-29T19:24:51.507" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25703" PostTypeId="1" AcceptedAnswerId="25706" CreationDate="2016-02-29T20:41:12.760" Score="0" ViewCount="1901" Body="&lt;p&gt;What is the highest service ceiling turboprop airplane,  that is fairly small, like maximum of 8 seats, and fairly cheap as well, not going over a million dollars. I looked at Cessna 425, and this plane has a service ceiling of 10km(33000ft), and this plane had the highest service ceiling, that fit the size and cost, that I could find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, basically , what plane out there has the greatest service ceiling, that  is small in size, like the Cessna 425, turboprop,  and cheap (under a million) ?&lt;/p&gt;&#xA;" OwnerUserId="13769" LastEditorUserId="12220" LastEditDate="2016-02-29T21:16:11.940" LastActivityDate="2016-02-29T22:36:21.663" Title="What is the highest service ceiling for turboprop airplane like a Cessna 425?" Tags="&lt;fuel&gt;&lt;altitude&gt;&lt;turboprop&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-03-16T09:09:18.943" ContentLicense="CC BY-SA 3.0" />
  <row Id="25705" PostTypeId="1" AcceptedAnswerId="25814" CreationDate="2016-02-29T21:00:25.640" Score="6" ViewCount="496" Body="&lt;p&gt;I was told it is a shield to avoid to blind the pilot during night flights when the strobes are on. Now, knowing the primary reason is, as far as I know, the above mentioned:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Does anyone know any official document where the definition of this device is mentioned?&lt;/li&gt;&#xA;&lt;li&gt;Does anyone know any reference where the effect on the wing tip aerodynamic is studied? Considering different speed regimes?&lt;/li&gt;&#xA;&lt;li&gt;Does anyone know if there are any regulations on this small device?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;As far as I know, this device can be founds on the following aircraft:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;King Air&lt;/li&gt;&#xA;&lt;li&gt;T-6 Texan&lt;/li&gt;&#xA;&lt;li&gt;Embraer Legacy 600&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;As can be seen, it can be found on models with and without wing tip devices.&lt;/p&gt;&#xA;&lt;p&gt;One thing that should be mentioned on aircraft fitted with winglet (not wing fence at the tip as those found on the A380), is that during the pull up manoeuvre, at take off, a mild/severe separation is generally observed on the inboard part of the winglet. Could the strobe shield fitted in the Embraer Legacy 600 mitigates this by re-energising  the boundary layer. It would be easy considering the amount of cross flow at the tip.&lt;/p&gt;&#xA;&lt;p&gt;Any official paper or informal discussion anywhere in the web would be very useful.&lt;/p&gt;&#xA;&lt;p&gt;More pictures can be found on these links:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://79ft.net/tag/mechanicing.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://79ft.net/tag/mechanicing.html&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J5WF8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J5WF8.jpg&quot; alt=&quot;strobe shield&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13770" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-04T14:29:37.760" Title="Does a strobe light shield act like a wingtip fence [or better sort of vortex generator]?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;wing-tip-vortex&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25706" PostTypeId="2" ParentId="25703" CreationDate="2016-02-29T21:36:46.950" Score="4" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-46&quot; rel=&quot;nofollow&quot;&gt;PA-46-500TP Malibu Meridian&lt;/a&gt; can climb to FL300 and you may be able to find a high time one for under a million. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/SOCATA_TBM&quot; rel=&quot;nofollow&quot;&gt;Socata TBM&lt;/a&gt; has a quoted ceiling of 31,000 ft and you may be able to find an older TBM 700 high time airframe for in and around a million. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the multi-engine category:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-42_Cheyenne&quot; rel=&quot;nofollow&quot;&gt;PA-42 Cheyenne&lt;/a&gt; will put you up to just under 36,000 ft and can be had used for under a million.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;http://beechcraft.txtav.com/en/king-air-c90gtx&quot; rel=&quot;nofollow&quot;&gt;Beech King Air C-90&lt;/a&gt; will get you up to 30,000 feet and can be found used on the lower end of the price spectrum. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2016-02-29T22:36:21.663" LastActivityDate="2016-02-29T22:36:21.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25707" PostTypeId="2" ParentId="25676" CreationDate="2016-03-01T01:12:32.260" Score="11" Body="&lt;p&gt;Gyroplanes have &lt;a href=&quot;http://www.7-gyroplane.com/home/case-studies/&quot;&gt;quite a few applications&lt;/a&gt;, but the problem is that anything they can do, others (helicopters/fixed wing aircraft) can do better.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The main advantage of a rotorcraft is that they can hover at a location; the gyroplanes are unable to do this, which is kind of a deal breaker.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The main advantage of the gyroplane is that they cost less and are easier to maintain, compared to other type of aircraft. However, most of the autogyros available in market are small ones and as the size scales up, this may vanish.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The gyroplanes are used mainly for low speed surveillance operations due to their low stall speed. Of course, helicopters can be used to do this, albeit at a higher cost&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;So basically, the autogyro can do &lt;em&gt;most&lt;/em&gt; of the things the helicopters/small GA aircraft can do at a lower cost. This low operational cost may be its main advantage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm not aware of anything the autogyro can do which the others cannot do though.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-01T01:12:32.260" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25708" PostTypeId="1" CreationDate="2016-03-01T02:08:36.497" Score="6" ViewCount="381" Body="&lt;p&gt;Does anyone know the part number for the Boeing 727 AC Generator Drive panel?  I have searched the Internet and have not found the part number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eCrpF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eCrpF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.2040-parts.com/boeing-727-ac-generator-drive-panel-used-aircraft-part-i638595/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="13772" LastEditorUserId="3201" LastEditDate="2016-03-01T22:16:10.203" LastActivityDate="2017-07-10T22:58:02.260" Title="What is the Boeing 727 AC Generator Panel Part Number?" Tags="&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25709" PostTypeId="1" AcceptedAnswerId="25712" CreationDate="2016-03-01T02:20:06.380" Score="9" ViewCount="3849" Body="&lt;h2&gt;Introduction&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Pop-up IFR clearances are an accepted way to transition from VFR to IFR flight by obtaining an IFR clearance. They are well documented from a controller's perspective in &lt;a href=&quot;http://www.avweb.com/news/features/Popup-Clearances-225328-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Tarrance Kramer article&lt;/a&gt; appearing in AvWeb and from a pilot's perspective in &lt;a href=&quot;http://www.avweb.com/news/system/183174-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this Rick Durdan article&lt;/a&gt; appearing in AvWeb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These related Aviation.SE questions also address the topic:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1361/12720&quot;&gt;How do you request a “pop up” IFR clearance?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/1849/12720&quot;&gt;How do you open and get a IFR clearance while in the air?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2646/12720&quot;&gt;How should I request an IFR approach at the end of a VFR flight?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Clearly, this is an accepted way to obtain an IFR clearance; I have made use of the option myself plenty of times.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Legal Background&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Now, pop-up clearances are often requested and granted with no previously filed IFR flight plan which, on the face of it, would seem to be in violation of &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.173&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.173&lt;/a&gt; which states (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may operate an aircraft in controlled airspace under IFR&#xA;  unless that person has—&lt;br&gt;&#xA;  (a) &lt;strong&gt;&lt;em&gt;Filed&lt;/strong&gt; an IFR flight plan&lt;/em&gt;; and&lt;br&gt;&#xA;  (b) Received an appropriate ATC clearance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFar.nsf/FARSBySectLookup/91.169&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.169&lt;/a&gt; gives the information required for filing that required IFR flight plan, which states, in part (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Unless otherwise &lt;strong&gt;authorized&lt;/strong&gt; by ATC&lt;/em&gt;, each person filing an IFR flight plan must include in it the following information: [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(I omit the long list of actual information)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Question&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The first part of my question is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Does a request for a pop-up IFR clearance constitute filing a flight&#xA;plan?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there an unwritten (or perhaps written) understanding that the request for the IFR clearance constitutes filing a flight plan to the extent required by 14 CFR 91.173?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The second part of my question is:&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Why is the full list of information required&#xA;for filing an IFR flight plan not required, in fact, of a pilot&#xA;requesting a pop-up IFR clearance?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If ATC issues an IFR clearance without this information, is that a tacit, but legally valid, authorization to exclude the information otherwise required by 14 CFR 91.169?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Is all this actually codified somewhere that I am not aware of?&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-04-18T08:25:55.993" Title="Does a request for a Pop-Up IFR clearance constitute filing a flight plan?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;clearance&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25710" PostTypeId="2" ParentId="25705" CreationDate="2016-03-01T02:31:39.847" Score="0" Body="&lt;p&gt;Vortex generators are located along the wing, not at the wing tip.  They are designed to make the wing stall break over a greater range of angle of attack.  What you show at the wing tip will not have a similar effect as a VG.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-03-01T02:31:39.847" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25712" PostTypeId="2" ParentId="25709" CreationDate="2016-03-01T06:48:09.450" Score="11" Body="&lt;p&gt;I think &lt;a href=&quot;https://aviation.stackexchange.com/questions/25709/does-a-request-for-a-pop-up-ifr-clearance-constitute-filing-a-flight-plan#comment61912_25709&quot;&gt;Porcupine911&lt;/a&gt; nailed the first question perfectly with the reference to &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7110.65W&lt;/a&gt;: A &quot;pop-up&quot; IFR clearance counts as filing an IFR flight plan.&lt;br&gt;&#xA;ATC considers it an &quot;airfiled&quot; flight plan (VFR-to-IFR), and the controller talking to you will take at least the bare minimum information necessary to enter you into the ATC system and generate a flight plan / strip for your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Your second question is a little more complicated, but the short answer is that pop-up IFR clearances aren't &quot;tacit authorization to omit information required by 91.169&quot;, but controllers are busy people and don't have time to key all that into the computer when they're supposed to be working traffic.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer version is that what you probably &lt;em&gt;should&lt;/em&gt; be doing to get an IFR clearance in-flight is calling the local flight service station over the radio and air-filing your IFR flight plan with them, then checking in with ATC (who will have all the information Flight Service took from you and entered into the computer, without having to tie up their frequency interrogating you for it). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA (or at least the ATC organization) is not without a heart though: They understand that if you're calling them for a pop-up IFR clearance it means you're in a bit of a situation (like IMC closing in on you with no good &quot;out&quot; that will allow you to remain VFR) and you need to get into the system before you hit the ground, a building, or another aircraft.&lt;br&gt;&#xA;Giving the controller the bare minimum skeleton of a flight plan allows them to get you into the system and under positive ATC control to ensure you're operating at a safe altitude without any traffic conflicts, which satisfies the first of the three ATC operational criteria (&quot;Safe&quot;) -- the other two (Orderly &amp;amp; Expedient) are a lower priority and can be dealt with later.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-03-01T06:53:58.217" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25714" PostTypeId="1" CreationDate="2016-03-01T07:14:28.393" Score="28" ViewCount="2059" Body="&lt;p&gt;I am a low-time pilot, of approximately 200 hours. I trained on the DA20 and DA40, designs that are derived from the Diamond touring motor glider design(s) of the early 1990s. I anticipate getting my Glider rating this summer in the US. As I've considered getting my glider rating, I've noticed a habit that I've developed that closely matches the &quot;glider pilot mentality&quot; which does not seem so prevalent in my training for ASEL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always preferred using a forward-slip for landing with the engine idle, as opposed to using the throttle to adjust the descent angle. I attribute this to multiple factors, such as being aware of the design history of the DA20, training with its more &quot;glider-like&quot; characteristics, and a general paranoia of the engine quitting on base or final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This brings me to the following questions: &lt;strong&gt;What are the safety considerations for this type of approach? Are there limitations on the use of sideslip on light airplanes?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Supplement questions, for possible merge or replacement of above. (Taken from my comment below)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Instead of puttering in using throttle, why don't we use side slips all the time?&lt;/li&gt;&#xA;&lt;li&gt;Why don't most/more GA aircraft have spoilers or dive brakes?&lt;/li&gt;&#xA;&lt;li&gt;Is the mentality of &quot;every landing is an engine-out landing&quot; creating more danger than it alleviates?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13379" LastEditorUserId="13379" LastEditDate="2016-03-05T08:58:36.103" LastActivityDate="2016-03-05T08:58:36.103" Title="Is it safe and effective to have &quot;glider pilot mentality&quot; when landing single-engine fixed-wing aircraft?" Tags="&lt;safety&gt;&lt;flight-training&gt;&lt;glider&gt;&lt;pilot-technique&gt;&lt;single-engine&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25715" PostTypeId="1" CreationDate="2016-03-01T08:52:06.777" Score="2" ViewCount="498" Body="&lt;p&gt;I'm interested in building a working model of a turbojet engine, but I don't have a lot of supplies. So I'm wondering if it's possible to use aluminum cans for construction, for every body part. While we're on this topic, would the heat melt the aluminum?&lt;/p&gt;&#xA;" OwnerUserId="12355" LastActivityDate="2016-03-08T11:51:10.243" Title="Is it possible to build a turbojet engine with aluminum cans? (Soft drink cans)" Tags="&lt;turbofan&gt;" AnswerCount="1" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25716" PostTypeId="2" ParentId="25714" CreationDate="2016-03-01T09:40:40.940" Score="16" Body="&lt;p&gt;Diamond aircraft are very low drag and do not have particularly effective flaps, so sideslipping is certainly an effective way to approach the problem. However there are considerations you need to be aware of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A steeper approach can bring you down on top of another airplane on final approach. Maintaining a more common approach angle is safer as it is less likely to bring you into a potential collision, and keeps you on a path where other pilots are likely to see you&lt;/li&gt;&#xA;&lt;li&gt;Steep sideslips are not particularly comfortable for passengers, the steep angle and different feel can be frightening&lt;/li&gt;&#xA;&lt;li&gt;Having your engine idle for long periods can lead to ice buildup in your carburetor, even with the heat on. It also lets your engine cool down quite a bit. Keeping some revs on keeps things warm up front&lt;/li&gt;&#xA;&lt;li&gt;A steep approach angle makes it harder to round out accurately&lt;/li&gt;&#xA;&lt;li&gt;A mishandled sideslip can lead to a loss of control. If the ball is to one side and you get past the critical AoA you will be executing a snap roll at low altitude, which = &lt;strong&gt;bad&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There's nothing wrong with using sideslip and keeping up with the technique - it's very useful if you catch a thermal on approach, are given a slam dunk approach, or need to get on the ground fast. For me it's not the best tool for normal approaches when you have alternatives, especially if you come in at a very steep approach angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One technique I've heard of for approaches on Diamond single engine airplanes is to use a combination of both: a slight sideslip dirties up the airflow enough to create some useful drag, and power is used to maintain the approach angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't think of a light airplane you can't sideslip, or any airplane you can't sideslip for that matter (perhaps the Mig 15). Sideslipping was used successfully in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gimli_Glider&quot; rel=&quot;nofollow&quot;&gt;Gimli Glider incident&lt;/a&gt;, and that was a 767! There are limitations which will be listed in the aircraft documentation, for instance you should not sideslip a C152 above 20 degrees of flap. If I'm flying a C150/152/170/172 I follow that rule. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1696" LastEditDate="2016-03-04T15:35:25.460" LastActivityDate="2016-03-04T15:35:25.460" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25717" PostTypeId="1" CreationDate="2016-03-01T10:39:01.863" Score="4" ViewCount="439" Body="&lt;p&gt;Isn't it the job of the air traffic controller to assign altitudes and make sure airplanes do not collide in mid-air? Is having TCAS mandated or optional? If it is a mandate, then is there a mechanism to notify other airplanes that TCAS is off?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="62" LastEditDate="2016-03-01T15:57:40.263" LastActivityDate="2016-03-01T16:18:13.693" Title="What is the need for TCAS?" Tags="&lt;tcas&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25719" PostTypeId="1" CreationDate="2016-03-01T12:56:21.390" Score="7" ViewCount="1103" Body="&lt;p&gt;When a pilot receives the message : THE RUNWAY IS STERILE, what is the meaning?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-03-02T21:25:06.790" Title="What does STERILE RUNWAY mean?" Tags="&lt;phraseology&gt;&lt;closed-runways&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25720" PostTypeId="1" AcceptedAnswerId="25727" CreationDate="2016-03-01T13:04:17.507" Score="5" ViewCount="324" Body="&lt;p&gt;Contaminated Runway is used to say that the runway surface area (25%) is covered by 3.0 mm or more of: water, slush, snow and ice. But is it also possible to use this term to say about: heavy rubber, oil spill, debris or other substances are on the runway surface?&lt;/p&gt;&#xA;" OwnerUserId="12207" LastActivityDate="2016-03-02T14:36:31.367" Title="Can we use the term CONTAMINATED RUNWAY for other meanings, such as: oil spill or debris on the runway?" Tags="&lt;runways&gt;&lt;phraseology&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25721" PostTypeId="2" ParentId="25717" CreationDate="2016-03-01T13:12:14.243" Score="3" Body="&lt;p&gt;TCAS is part of a defense in depth strategy to reduce air accidents. ATC does not cover all areas, so TCAS adds protection where ATC coverage is missing. ATC is not infallible: humans can make errors and computers can go down. With TCAS pilots can get life-saving warnings even in zero visibility, without reliance on any ground based system. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-03-01T13:12:14.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25722" PostTypeId="2" ParentId="25717" CreationDate="2016-03-01T13:32:54.690" Score="3" Body="&lt;p&gt;It is the job of the ATC to assign the aircraft altitudes and ensure their safety. But consider the following situations:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;There is no ATC coverage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;(one of the) The aicraft fails to respond to the ATC directions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft follows the ATC directions, but there is an error either in the aircraft systems/pilot actions or in the ATC directions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In these situations, the TCAs acts as the next layer of defence against mid-air collisions, acting independently of the ATC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most of the regulatory authorities (FAA, EASA etc) &lt;a href=&quot;https://en.wikipedia.org/wiki/Traffic_collision_avoidance_system#Regulatory_situation_around_the_world&quot; rel=&quot;nofollow&quot;&gt;mandate TCAS&lt;/a&gt; (usually TCAS II) in the civil aircraft beyond a certain capacity, though the requirements vary from country to country. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-01T13:32:54.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25723" PostTypeId="2" ParentId="25719" CreationDate="2016-03-01T13:55:31.390" Score="6" Body="&lt;p&gt;It means that aircraft are not allowed to takeoff/land in that runway. From a &lt;a href=&quot;https://www.bas.ac.uk/wp-content/uploads/2015/12/PIM_Issue4_Section7App5_AL6_OpsRotheraVisitingAircraftInfo_151202.pdf&quot;&gt;British Antartic Survey Document on the Rothera Research Station&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;BAS  procedures  require  a  sterile  runway  and  airspace  at  Rothera  for  all  periods where  the  BAS  DASH  7  has  passed  PNR  until  it has  landed.  Aircraft  will NOT be allowed to takeoff, land, hold in the overhead or the vicinity of the airfield during this period. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-01T13:55:31.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25724" PostTypeId="2" ParentId="25709" CreationDate="2016-03-01T13:56:00.360" Score="2" Body="&lt;p&gt;Here are two relevant definitions from the FAA's &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FLIGHT PLAN− Specified information relating to the intended flight of&#xA;  an aircraft that is &lt;strong&gt;filed orally or in writing&lt;/strong&gt; with an FSS or an ATC&#xA;  facility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ABBREVIATED IFR FLIGHT PLANS− An authorization by ATC requiring pilots&#xA;  to submit only that information needed for the purpose of ATC. &lt;strong&gt;It&#xA;  includes only a small portion of the usual IFR flight plan&#xA;  information&lt;/strong&gt;. In certain instances, this may be only aircraft&#xA;  identification, location, and pilot request. Other information may be&#xA;  requested if needed by ATC for separation/control purposes. &lt;strong&gt;It is&#xA;  frequently used by aircraft which are airborne and desire an&#xA;  instrument approach&lt;/strong&gt; or by aircraft which are on the ground and desire&#xA;  a climb to VFR-on-top.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So according to the FAA's own definitions, a flight plan may be filed orally with ATC, and an abbreviated flight plan is specifically intended for pop-up clearances.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-01T13:56:00.360" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25725" PostTypeId="2" ParentId="25691" CreationDate="2016-03-01T14:00:51.883" Score="2" Body="&lt;p&gt;Thanks Guys. I've contacted the manufacturer and they said that there is an approved cable, only sold by avionics shops, that will connect an old fashioned serial port to the data port on the panel. If I get a USB to serial computer, I may be able to use Windows 10 to install the update. Maybe I'll have to downgrade to Win7.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I asked if there was a published end-of-service date for the unit and they stated that there was not. I also asked if there was a guarantee of future database availability for any period into the future and she said that there was no guarantee, but no plans that she knew of to phase the unit out.&lt;/p&gt;&#xA;" OwnerUserId="13766" LastActivityDate="2016-03-01T14:00:51.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25726" PostTypeId="2" ParentId="9357" CreationDate="2016-03-01T14:28:13.260" Score="6" Body="&lt;p&gt;I was struck in the forehead in 1983 from the discharge off a CH-53. I was wearing a kelvar helmet which was split down the middle from the strike, heart rate slowed down to 4 beats a minute thought I was a gone. I was stationed at camp Pendleton USMC when it happened.&lt;/p&gt;&#xA;" OwnerUserId="13783" LastEditorUserId="12220" LastEditDate="2016-03-01T14:33:08.267" LastActivityDate="2016-03-01T14:33:08.267" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25727" PostTypeId="2" ParentId="25720" CreationDate="2016-03-01T14:33:59.557" Score="7" Body="&lt;p&gt;From the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Pilot/Controllers Glossary Book&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CONTAMINATED RUNWAY− A runway is&#xA;  considered contaminated whenever standing water,&#xA;  ice, snow, slush, frost in any form, heavy rubber, or&#xA;  other substances are present. A runway is contaminated&#xA;  with &lt;strong&gt;respect to rubber deposits or other&#xA;  friction-degrading substances&lt;/strong&gt; when the average&#xA;  friction value for any 500-foot segment of the runway&#xA;  within the ALD fails below the recommended&#xA;  minimum friction level and the average friction value&#xA;  in the adjacent 500-foot segments falls below the&#xA;  maintenance planning friction level. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(See also &lt;a href=&quot;https://www.iata.org/iata/RERR-toolkit/assets/Content/Contributing%20Reports/ICAO_Circular_on_Rwy_Surface_Condition_Assessment_Measurement_and_Reporting.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO Circular on Runway Surface Condition Assessment Measurement and Reporting)&lt;/a&gt; Thanks to &lt;a href=&quot;https://aviation.stackexchange.com/users/3201/mins&quot;&gt;mins&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So this covers rubber and oil, but not debris.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, from searching the glossary there are no instances of the word &quot;debris&quot; in the document. Usually if debris or oil were noticed on a runway, ATC would close the runway (issue a NOTAM) and then use an alternate runway until the debris or oil were cleaned up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a pilots perspective, if you notice debris on the runway just tell ATC (provided you didn't hit it), and they will close the runway for a FOD (foreign object debris) check. My local airport does this usually twice a day or more, typically by running a car down the runway looking for debris. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-02T14:36:31.367" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25728" PostTypeId="1" CreationDate="2016-03-01T15:56:59.400" Score="0" ViewCount="552" Body="&lt;p&gt;About a month ago I encountered an unusual landing during a flight from Bangkok to Krabi airport. We were flying Boeing 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We took off 30 minutes late. Our flight should've taken 90 minutes but it actually took less than 70 minutes so we arrived almost on time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The seatbelt sign turned on around the 60th minute while we were still probably in 10000 meters (I don't know the cruising altitude for sure). The whole landing took less than 10 minutes. I guess the landing gear was deployed at around 6000 meters which seemed unusually high to me. The pilot also performed several rather sharp roll maneuvers and at one point he broke his descend and even entered a rather sharp climb. All this with landing gear out. I have to say that many passengers were quite terrified at the moment. The landing itself was hard but not that much.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been  wondering if it was a common maneuver (to decrease speed perhaps?) and would be interested to learn more about it. Does it have something to do with the flight speedup? How is it even possible to be so much faster on such a short flight?&lt;/p&gt;&#xA;" OwnerUserId="13786" LastEditorUserId="12220" LastEditDate="2016-03-01T21:49:37.433" LastActivityDate="2016-03-01T21:49:37.433" Title="Was this an unusual landing sequence for an airliner?" Tags="&lt;airliner&gt;&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="12" ClosedDate="2016-03-10T17:16:06.220" ContentLicense="CC BY-SA 3.0" />
  <row Id="25729" PostTypeId="2" ParentId="25717" CreationDate="2016-03-01T15:57:09.707" Score="3" Body="&lt;p&gt;TCAS is used as a last line of defense to avoid a collision. An air traffic may be distracted or occupied elsewhere and so no instruction is given to the two aircraft. The TCAS overrules any instruction given by air traffic control and the pilots must specific that they are following TCAS over the radio. For example if an aircraft is instructed to descend by air traffic control and TCAS is requesting the aircraft to climb the aircraft will begin a climb. TCAS will order one aircraft to climb and the other aircraft to descend to safely end the conflict between the two aircraft.&lt;/p&gt;&#xA;" OwnerUserId="13787" LastEditorUserId="5517" LastEditDate="2016-03-01T16:18:13.693" LastActivityDate="2016-03-01T16:18:13.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25730" PostTypeId="2" ParentId="25728" CreationDate="2016-03-01T16:42:01.097" Score="6" Body="&lt;p&gt;Why do you think the flight &quot;should&quot; take 90 minutes?&lt;br&gt;&#xA;You really mean it was listed for 90 minutes on the schedule.&lt;Br&gt;&#xA;Airlines almost always pad their scheduled times so that their on-time arrivals stats are favorable, and to account for normally expected delays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scheduled time is also typically measured &quot;gate-to-gate&quot;, while most passengers only observe the flight-time (takeoff-to-landing)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I see the distance is 350 miles, and would probably take a 737 about 60 minutes of actual flight time.  So I don't think your flight was speeding or otherwise behaving abnormally.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-03-01T16:42:01.097" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25732" PostTypeId="2" ParentId="9357" CreationDate="2016-03-01T17:09:03.023" Score="13" Body="&lt;p&gt;I am a Naval Aviator and as part of my water survival training, I was deposited by boat off the coast of Florida and picked up by helicopter.  It was a &lt;strong&gt;&lt;em&gt;huge&lt;/em&gt;&lt;/strong&gt; point of emphasis that we let the helicopter's rescue hook touch the water to discharge any built up static before we touched it.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No one in my class grabbed it before it hit the water, so I can't speak to how bad the shock would have been.&lt;/p&gt;&#xA;" OwnerUserId="8210" LastActivityDate="2016-03-01T17:09:03.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25734" PostTypeId="2" ParentId="23381" CreationDate="2016-03-01T20:14:55.470" Score="12" Body="&lt;p&gt;If the pilot engaged in combat, and simply ran out of ammunition, surrendering isn't something that has to be accepted by the opposing party. The rule is, you need to surrender on first sight of the enemy. Once you engage in combat all bets are off and you can be destroyed even if you release the canopy and throw up your hands (not recommended!) See, people get a peculiar sentiment when you shoot at them. They appreciate that you missed, but they don't take kindly that you offered surrender after you go winchester on the missiles and bullets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, while you are surrendering. Assuming you didn't engage in combat, consider learning the other side's language and make sure you surrender in a top of the line aircraft. For example, Viktor Belenko defected in a Mig-25 in 1976 by flying it to Japan. This was a very valuable aircraft which he traded for a carton of American cigarettes and a million dollars. (ok just kidding, but he did get a nice trust fund set up for him when President Ford accepted his asylum plea.)&lt;/p&gt;&#xA;" OwnerUserId="13789" LastActivityDate="2016-03-01T20:14:55.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25735" PostTypeId="1" CreationDate="2016-03-01T20:21:54.863" Score="16" ViewCount="8816" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jIj5g.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jIj5g.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to ICAO's classification, LPV SBAS approach is in the APV group, because it doesn't meet some specifications for precision approaches. But what exactly does it not meet?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Glossary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LPV: Localizer performance with vertical guidance&lt;/li&gt;&#xA;&lt;li&gt;SBAS: Space-based augmentation system&lt;/li&gt;&#xA;&lt;li&gt;APV: Approach with vertical guidance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13790" LastEditorUserId="14897" LastEditDate="2018-09-19T20:31:39.633" LastActivityDate="2018-09-19T20:31:39.633" Title="Why isn't an LPV SBAS approach considered a precision approach according to ICAO?" Tags="&lt;icao&gt;&lt;iaps&gt;&lt;gnss&gt;&lt;performance-based-navigation&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25736" PostTypeId="1" AcceptedAnswerId="25738" CreationDate="2016-03-01T20:29:01.977" Score="97" ViewCount="21066" Body="&lt;p&gt;Does anyone know why we use Affirm and Negative in RT, rather than Yes and No? I assume it's to prevent confusion with accents and other languages - but Yes and No sound very different to me!&lt;/p&gt;&#xA;" OwnerUserId="13792" LastEditorUserId="13792" LastEditDate="2016-03-05T12:47:48.427" LastActivityDate="2018-10-10T14:12:40.083" Title="Why is &quot;Affirm / Negative&quot; used instead of &quot;Yes / No&quot;?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="25737" PostTypeId="2" ParentId="25736" CreationDate="2016-03-01T20:42:14.927" Score="24" Body="&lt;p&gt;&quot;Affirmative&quot; and &quot;Negative&quot; come from the radio procedure words that went into the aviation world. As a comment above it also adds on more complexity and length to the statement so that the receiver can understand even if the transmission got garbled up or cut off in some parts. It would be really bad if the &quot;yes&quot; or &quot;no&quot; got cut off somehow from the transmission which would be really easy because they take a really short time to say, making it easy to loose the entire word over radio.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-01T20:53:01.913" LastActivityDate="2016-03-01T20:53:01.913" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25738" PostTypeId="2" ParentId="25736" CreationDate="2016-03-01T20:44:15.653" Score="69" Body="&lt;p&gt;Because it makes you sound cool and very Top Gun!&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Negative Ghostrider. The pattern is full&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Seriously though, short words, especially at the end and beginning of transmissions are often clipped. When everything is busy, a question might only need a &amp;quot;yes/no&amp;quot; reply. Yes/no is easily lost in radio communication. Affirm/negative are not.&lt;/p&gt;&#xA;&lt;p&gt;Also, with English native speakers, yes and no are absolute.  In some languages, yes and no are relative to the question.&lt;/p&gt;&#xA;&lt;p&gt;Interpret this:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Don't you have enough fuel to make the field?&lt;/p&gt;&#xA;&lt;p&gt;Yes, we don't.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;No, we don't.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Of course, the question is not good as it contains a negative but, if a question can only have an &amp;quot;affirmative or negative&amp;quot; response, it also helps the questioner to form a good question:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Can you make the field?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This can only be &amp;quot;affirmative (always shortened to &amp;quot;affirm&amp;quot; to avoid confusion) or &amp;quot;negative&amp;quot;.  There is no interpretation.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-03T10:25:43.880" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="25739" PostTypeId="1" AcceptedAnswerId="25740" CreationDate="2016-03-01T20:54:58.267" Score="11" ViewCount="53669" Body="&lt;p&gt;What are the main differences between these two types of fuselages?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="12220" LastEditDate="2016-03-01T20:59:43.057" LastActivityDate="2016-10-15T05:24:33.950" Title="What is the difference between a monocoque and semi-monocoque fuselage type?" Tags="&lt;aircraft-design&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25740" PostTypeId="2" ParentId="25739" CreationDate="2016-03-01T21:06:57.323" Score="11" Body="&lt;p&gt;A monocoque fuselage has its skin holding the skeleton structure together while the semi-monocoque has both the skin and the skeleton holding together. Semi-monocoque also has &quot;stringers&quot; running horizontally down the plane to help hold the frame together. The monocoque fuselage also cannot be used for airframes after a certain size (small aircraft with single engine), but the semi-monocoque has been used from single piston engines to commercial airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A monocoque design would also have a safety risk involved if the skin was damaged because it is the load-bearing structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TpWYH.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TpWYH.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image and some text &lt;a href=&quot;https://www.quora.com/What-is-the-difference-between-monocoque-construction-and-semi-monocoque-construction-in-aircraft&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-02T13:48:49.320" LastActivityDate="2016-03-02T13:48:49.320" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25743" PostTypeId="2" ParentId="25736" CreationDate="2016-03-02T07:09:35.817" Score="109" Body="&lt;p&gt;Why do we say &quot;TANGO&quot; on the radio for the letter &quot;T&quot;? Because &quot;T&quot; could get garbled or misunderstood to be &quot;B&quot;, &quot;E&quot;, &quot;or &quot;V&quot;. &quot;NO&quot; could become &quot;oh?&quot;, &quot;YES&quot; could become &quot;us&quot;, and so on...the possible interpretations and permutations of short, monosyllabic words are many. Use a big word and it will be hard to confuse with others...&lt;/p&gt;&#xA;" OwnerUserId="13795" LastActivityDate="2016-03-02T07:09:35.817" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25744" PostTypeId="2" ParentId="25739" CreationDate="2016-03-02T11:29:52.203" Score="10" Body="&lt;p&gt;The main difference between the two is the way the loads are carried by the aircraft structure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The earliest aircraft had an underlying truss structure that carried the load, with fabric covering this load bearing skeleton. The outer shell carried no loads and from the structural viewpoint, was basically dead weight. The image below shows the underlying structure of the Blériot XI&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wqlEZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wqlEZ.jpg&quot; alt=&quot;Bleroit XI&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &lt;a href=&quot;//commons.wikimedia.org/wiki/User:J.Klank&quot; rel=&quot;noreferrer&quot; title=&quot;User:J.Klank&quot;&gt;J.Klank&lt;/a&gt; - Own work, CC BY 3.0, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=7219409&quot; rel=&quot;noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=7219409&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later, the aircraft structure was designed so that the the skin itself was a mainload carrying member. This type of construction was called the monocoque, which is a French term for single shell (or hull). A good example is the fuselage of the De Haviland Mosquito (which is all the more impressive as it was made of plywood). The fuselage was made in two monocoque halves, which were joined together, which can be seen in the following figure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MhOaD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MhOaD.jpg&quot; alt=&quot;Monocoque&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;De Haviland Mosquito monocoque structure- image from &lt;a href=&quot;http://pistonwings.tumblr.com/post/98704721270/nicknamed-the-wooden-wonder-the-de-havilland&quot; rel=&quot;noreferrer&quot;&gt;pistonwings.tumblr.com&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the skin carries the entire load, the strength requirements mean that this technique cannot be used for aircraft beyond a certain level. For thin skinned structures, buckling is critical issue, which affects the load carrying capcity. Large structures can be made that can carry load only via the skin, but support is still required. For example, the fuel tanks of Altas ICBMs carried the entire load on the skin, but required internal pressure to maintain the shape, without which they collapsed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The semi-monocoque is in between the above two- here, a stressed skin is used that takes some of the load, but is reinforced by the underlying structure, which also takes load. Basically, both the skin and the underlying structure share the load. Most of the aircraft today use this type of construction, from small GA aircraft to the large commercial airliners. For example, the image below shoes a fuselage section of Airbus A350XWB, which features this type of construction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FuQXW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FuQXW.jpg&quot; alt=&quot;A350&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.a350xwb.com/industrial-process/&quot; rel=&quot;noreferrer&quot;&gt;a350xwb.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-03-03T00:15:10.033" LastActivityDate="2016-03-03T00:15:10.033" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25745" PostTypeId="1" CreationDate="2016-03-02T14:18:56.437" Score="0" ViewCount="263" Body="&lt;p&gt;The Bombardier CSeries and the Boeing 737 are two aircraft in the same class. Their nose shapes are very different from each other though as can be seen in these two images. What are the major aerodynamic differences between these two nose designs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CSeries:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/H1uJT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H1uJT.jpg&quot; alt=&quot;CSeries&quot;&gt;&lt;/a&gt;&#xA;Image &lt;a href=&quot;http://www.airliners.net/photo/Swiss-International-Air/Bombardier-CSeries-CS100/2718651/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ho1Fs.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ho1Fs.jpg&quot; alt=&quot;Boeing 737&quot;&gt;&lt;/a&gt;&#xA;Image &lt;a href=&quot;http://www.airliners.net/photo/Delta-Air-Lines/Boeing-737-732/1850974/M/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/12915/why-do-boeing-and-airbus-have-distinctively-different-nose-designs&quot;&gt;This&lt;/a&gt; question and answer set don't really answer my question here because it talks about a generic nose form of aircraft made by Boeing and Airbus. I am looking for specific aerodynamic differences between &lt;em&gt;nose cone shapes on specific models of Boeing and Bombardier aircraft&lt;/em&gt;. The Airbus part of that question cannot answer the Bombardier part of this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That question also does not talk about specific model as it says at the bottom: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This image is only an example and my question is not about any specific model.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I want the specifics for the nose cone shapes of Boeing 737 and the Bombardier CSeries, not specifics on the aircraft themselves. &lt;em&gt;This is more like asking for for the aerodynamic difference, for example, between a blunt nose and an ogive nose&lt;/em&gt; than something to do with aircraft corporations.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-02T15:07:35.477" Title="What are the aerodynamic differences between the nose designs of the CSeries and the Boeing 737?" Tags="&lt;aircraft-design&gt;&lt;boeing-737&gt;&lt;nose&gt;&lt;airbus-a220&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-03-02T15:24:34.477" ContentLicense="CC BY-SA 3.0" />
  <row Id="25746" PostTypeId="1" AcceptedAnswerId="25749" CreationDate="2016-03-02T15:21:23.117" Score="21" ViewCount="11075" Body="&lt;p&gt;For example a Cessna Grand Caravan doesn't have a pressurization system, but a Phenom 100  is pressurized, so what are the main reasons a manufacturer has to build an aircraft with a pressurization system: altitude, speed, etc?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-07T23:06:23.273" LastActivityDate="2016-06-13T15:15:43.900" Title="When is an aircraft required to be pressurized?" Tags="&lt;faa-regulations&gt;&lt;aircraft-systems&gt;&lt;cabin-pressure&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25749" PostTypeId="2" ParentId="25746" CreationDate="2016-03-02T15:48:42.213" Score="22" Body="&lt;p&gt;The main reason is that it's simpler than having everyone wear supplemental oxygen masks. There is no specific requirement for pressurizing an airplane but there are requirements for supplemental oxygen as per FAR 91.211 &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) General. No person may operate a civil aircraft of U.S. registry--&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) At &lt;strong&gt;cabin pressure altitudes&lt;/strong&gt; above 12,500 feet (MSL) up to and&#xA;  including 14,000 feet (MSL) unless the required minimum flight crew is&#xA;  provided with and uses supplemental oxygen for that part of the flight&#xA;  at those altitudes that is of more than 30 minutes duration; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) At &lt;strong&gt;cabin pressure altitudes&lt;/strong&gt; above 14,000 feet (MSL) unless the required&#xA;  minimum flight crew is provided with and uses supplemental oxygen&#xA;  during the entire flight time at those altitudes; and &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) At &lt;strong&gt;cabin pressure altitude&lt;/strong&gt; above 15,000 feet (MSL) unless each occupant of &gt; the aircraft is provided with supplemental oxygen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So by pressurizing the plane to under 15,000 ft you can fly over that altitude and not need to supply the passengers with supplemental oxygen for the duration of the flight. There are unpressurized piston planes that fly well into the flight levels but are required to carry supplemental oxygen and everyone aboard needs to use it, it's a look some people in general aviation don't mind, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lNfZX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lNfZX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.gaoperator.com/wp-content/uploads/2014/08/Cirrus-SR22-race-DC-pic.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a slight side note the engine does have an effect on this choice when it comes to light singles. Pressurization systems on turbo props/light jets pull their air from the compression stage of the turbine which is already compressing air so no extra compression hardware is needed. If you have chosen a piston engine for your design you need to drive some form of pressurization system which can add weight and complexity. There are a few pressurized piston planes out there like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mooney_M22_Mustang&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mooney Mustang&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_210&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cessna 210&lt;/a&gt; (came in both pressurized and un pressurized) and the &lt;a href=&quot;http://www.piper.com/aircraft/m-class/m350/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper M350&lt;/a&gt; (the only one currently in production).  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorDisplayName="user5664" LastEditDate="2016-06-13T15:15:43.900" LastActivityDate="2016-06-13T15:15:43.900" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25750" PostTypeId="2" ParentId="25746" CreationDate="2016-03-02T15:50:30.070" Score="3" Body="&lt;p&gt;The requirement for a pressurization system is dictated by the operating altitude. With increased altitudes the atmospheric pressure diminishes and so the concentration of oxygen available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;T o have an idea of what is consider a &quot;critical altitude&quot; for an average human we can have a look at &lt;a href=&quot;http://www.faa-aircraft-certification.com/91-211-supplemental-oxygen.html&quot; rel=&quot;nofollow&quot;&gt;FAR 91.211&lt;/a&gt;. It requires to  use oxygen when flying above 12500ft (3800m) for more than 30 minutes, and in any condition about 14000ft (4300m).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CS-23 certification requirements, which applies to aircraft 12500lb (5760kg) state the following for pressurization systems:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CS 23.841  Pressurised cabins &#xA;  (a)  If  certification  for  operation  over  7620m &#xA;  (25 000 ft) is requested, the aeroplane must be able &#xA;  to  maintain  a  cabin  pressure  altitude  of  not  more &#xA;  than  4572m  (15 000 ft)  in  event  of  any  probable &#xA;  failure or malfunction in the pressurisation system.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;These are the requirements a different aspect is what a manufacturer selects for its design which be influenced by other factors such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Comfort&lt;/li&gt;&#xA;&lt;li&gt;Marketing&lt;/li&gt;&#xA;&lt;li&gt;Safety&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-03-02T23:31:05.357" LastActivityDate="2016-03-02T23:31:05.357" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25751" PostTypeId="1" AcceptedAnswerId="25754" CreationDate="2016-03-02T16:13:57.897" Score="2" ViewCount="2127" Body="&lt;p&gt;What pilots use VOR navigation: GA pilots, commercial pilots, military pilots? When is it most used?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-03-02T19:11:22.490" Title="When is VOR navigation mostly used?" Tags="&lt;navigation&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25752" PostTypeId="2" ParentId="25746" CreationDate="2016-03-02T16:14:30.667" Score="4" Body="&lt;p&gt;Generally, the operating altitude of the aircraft determines whether the aircraft is pressurised or not.&lt;/p&gt;&#xA;&lt;p&gt;Regulations require the pressurised cabins to maintain certain perssure at the maximum operating altitude. For example, FAR 25-841 Pressurised cabins requires the cabin pressure to be &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2c5e4e6a386ede4111ae38faa3d7285e&amp;amp;mc=true&amp;amp;node=pt14.1.25&amp;amp;rgn=div5#se14.1.25_1841&quot; rel=&quot;noreferrer&quot;&gt;maintained at 8000 ft at the maximum operating altitude of the aircraft&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Pressurized cabins and compartments to be occupied must be equipped to provide a cabin pressure altitude of not more than 8,000 feet at the maximum operating altitude of the airplane under normal operating conditions.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Thought there is no set altitude of operation for the aircraft to be pressurised, it is required to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=2c5e4e6a386ede4111ae38faa3d7285e&amp;amp;mc=true&amp;amp;node=pt14.2.91&amp;amp;rgn=div5#se14.2.91_1211&quot; rel=&quot;noreferrer&quot;&gt;provide supplemental oxygen if the pressure altitudes are above 12500 ft&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;§91.211   Supplemental oxygen.&lt;/p&gt;&#xA;&lt;p&gt;(a) General. No person may operate a civil aircraft of U.S. registry—&lt;/p&gt;&#xA;&lt;p&gt;(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;&lt;/p&gt;&#xA;&lt;p&gt;(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and&lt;/p&gt;&#xA;&lt;p&gt;(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Basically, the aircraft designer has to decide between pressurising the aircraft (which increases weight and complexity) and having a non-pressurised fuselage and operate at a lower altitude, where the performance may suffer (or provide supplemental oxygen). It is a tradeoff and the decision usually depends on the aircraft design requirements. Note that pressurised aircraft also have to be provided with supplemental oxygen above FL250.&lt;/p&gt;&#xA;&lt;p&gt;For example, the Cessna Grand Caravan operates at a &lt;a href=&quot;http://www.wilderness-air.com/cessna_caravan.html&quot; rel=&quot;noreferrer&quot;&gt;cruise altitude of 12,000 ft&lt;/a&gt;, has an unpressurised fuselage, while the Phenom 100, which operates at a higher altitude has pressurised fuselage.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-02T16:14:30.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25753" PostTypeId="2" ParentId="25719" CreationDate="2016-03-02T18:54:12.993" Score="9" Body="&lt;p&gt;A &quot;sterile runway&quot; indicates that all traffic has been cleared from the runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This can include both traffic currently active on the runway as well as potentially other inbound traffic on approach, or even elsewhere on the tarmac - if it is deemed disruptive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A sterile runway is often used in emergency situations, such as when an airplane is coming in for an emergency landing. For the safety of both that plane as well as the others, the runway is cleared of any traffic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, this term is not exclusive to emergencies. For example, the FAA requires 250 feet on either side of a runway to be clear of airplanes when a Commercial Airplane lands. An airport that is smaller and has tight taxiways might have an aircraft taxiing closer than that. To be within FAA compliance, they would need to ensure that the runway was sterile and that there were no active planes taxiing within that 250 feet at the time of the commercial plane landing. An example of this rule being observed includes &lt;a href=&quot;http://www.iflysun.com/assets/pdfs/general-aviation/PilotNotice.pdf&quot;&gt;this notice posted by Friedman Memorial Airport in Hailey, ID&lt;/a&gt;, where they adjusted their procedures in response to FAA determinations in order to accommodate commercial traffic and maintain a &quot;sterile runway&quot;.&lt;/p&gt;&#xA;" OwnerUserId="13636" LastEditorUserId="13636" LastEditDate="2016-03-02T21:25:06.790" LastActivityDate="2016-03-02T21:25:06.790" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25754" PostTypeId="2" ParentId="25751" CreationDate="2016-03-02T19:11:22.490" Score="5" Body="&lt;p&gt;Im not sure on military but its still used by GA and Commercial pilots frequently. Although as has been noted in the comments it is slowly being downsized. It should also be noted that Commercial planes and GA planes use the same facilities and the same ATC. Once in the air a C172 may be given the same instructions as a 777 with the only differences being altitude and speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On one hand some &lt;a href=&quot;http://stoenworks.com/Tutorials/IFR,%20VOR%20Approaches.html&quot; rel=&quot;noreferrer&quot;&gt;VOR's are used for approaches&lt;/a&gt; to some airports. There is an effort to replace these with GPS approaches but there are still active VOR approaches out there today so anyone flying IFR to these airports needs them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are used for all sorts of IFR navigation and are often the terminal points on an airway, so you may be cleared after departure direct to a VOR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOR's can be used as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Holding_(aeronautics)&quot; rel=&quot;noreferrer&quot;&gt;fixed point for a hold in IFR flying&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;VOR navigation (and the use of paper charts for that matter) is still taught during PPL training since GPS is not necessarily installed in every plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_management_system&quot; rel=&quot;noreferrer&quot;&gt;FMS units use RNAV as a backup to GPS&lt;/a&gt; or inertial navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flighttraining.aopa.org/magazine/2000/December/200012_Features_The_ABCs_Of_VORs.html&quot; rel=&quot;noreferrer&quot;&gt;This AOPA article covers most of their uses&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I am a big fan of GPS and fly direct when the airspaces and clearances allow for it (VFR). That being said, the planes I rent generally have dual Nav/CDI installations which I frequently use to cross check my position with the GPS.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-03-02T19:11:22.490" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25755" PostTypeId="1" CreationDate="2016-03-02T20:03:53.343" Score="8" ViewCount="781" Body="&lt;p&gt;I currently live in Canada as a Permanent Resident and I recently received my Canadian Glider Pilot License. I will be going to Europe soon so I was wondering what I have to do to be able to fly a glider there. I will be going to the Netherlands if this makes any difference and I still have my Dutch Citizenship. Do I have to convert my license or just do some extra training?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also would it help if I got a FAA glider certificate/endorsement on top of my TCCA license?&lt;/p&gt;&#xA;" OwnerUserId="13811" LastEditorUserId="19" LastEditDate="2016-03-02T20:11:36.877" LastActivityDate="2017-04-01T19:10:57.653" Title="Can I fly a glider in Europe on a Canadian Glider License?" Tags="&lt;glider&gt;&lt;easa&gt;&lt;transport-canada&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25757" PostTypeId="2" ParentId="25736" CreationDate="2016-03-02T21:42:26.060" Score="17" Body="&lt;p&gt;It has to do with how radios in general work or worked. This is also true with telephones and some VOIP situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So take a plain old radio. You set it to a frequency, then you push a button to talk. When you push the button a circuit completes that lets electricity flow through some components (used to be the mic, but now it's gone through changes at times, but it doesn't matter). Next the sound of your voice is encoded and applied over a carrier signal. Because that carrier signal can't be sent 100% of the time there was/is a bit of distortion at the start and end. In some radios they use a beep or click to help &quot;establish&quot; the carrier signal. Remember that the simplest radios just applied your voices wave form over that of the carrier signals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, on the the receiving end, the same thing happens in reverse. The receiver can actually listen to the carrier signal the entire time, but there is a tiny delay as it starts to notice modulation of that signal, and starts &quot;decoding it&quot;. Again remember the simple radio has your voice as a modulation of the carrier wave. These days there is a lot of logic on this end to filter out noise, but even if there wasn't it would still take a tiny amount of time to &quot;see&quot; that the carrier wave changed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you have several points of distortion and delay at the start and end of a message;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;User pressing the button&lt;/li&gt;&#xA;&lt;li&gt;The mic circuits &quot;turning on&quot;&lt;/li&gt;&#xA;&lt;li&gt;The start of signal modulation&lt;/li&gt;&#xA;&lt;li&gt;The start of signal demodulation&lt;/li&gt;&#xA;&lt;li&gt;The Receiving end starting to &quot;play back&quot; the signal.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Add to that all kinds of distortion and interference, and the fact that as people we have a tendency to think along the lines of &quot;push button -&gt; talk&quot; so fast that we often start &quot;talking&quot; before we are actually transmitting, and you can get some pretty messed up messages. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To combat that there are a few common things that are done.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Using longer words&lt;/li&gt;&#xA;&lt;li&gt;Limiting vocabulary to common words&lt;/li&gt;&#xA;&lt;li&gt;A set of hand shake phrases that ensure that both sides are getting the same thing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For example (not from anything in particular):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You want pizza&lt;br&gt;&#xA;  ooo want pizza&lt;br&gt;&#xA;  ooo ..aunt... pee..ah  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While a bit odd, all three could be understood if you're having a conversation about dinner.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Yes&lt;br&gt;&#xA;  ess&lt;br&gt;&#xA;  sss&lt;br&gt;&#xA;  ye..&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is harder to understand than &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Affirm&lt;br&gt;&#xA;  ..Firm.&lt;br&gt;&#xA;  Affir..&lt;br&gt;&#xA;  Ah.ff.   &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Specially when you are asking a yes or no question. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No&lt;br&gt;&#xA;  oh&lt;br&gt;&#xA;  n...&lt;br&gt;&#xA;  ...  (this is actually pretty common as yes and no are fast words to say)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you say into you radio &quot;Do you want Pizza&quot; and you get back: &quot;...&quot;, your SOL. If you get back &quot;oh&quot;, is that &quot;oh I don't know&quot; or the end of no? If you get back &quot;Neg..&quot; or &quot;N....itive&quot; or &quot;Negiti..&quot; You're still in good shape ( you have your answer).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many things radio operators are taught to do to make sure they can understand one another in less than perfect conditions. Using &quot;longer&quot; words is one, using distinct words is another, and using scripted responses and questions is a third.  It's also important to remember that rarely is the radio a &quot;primary job&quot; it's almost always a  &quot;secondary job&quot;. The pilot needs to communicate, but communication can't be so cumbersome that it gets in the way of actually flying. So whatever system is in place to cover the distortion and what-not has to be easy, and widely understood. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you had two people with training, and they were taught that the question: &quot;Do you want pizza?&quot; could only EVER be answered with &quot;... Yes ...&quot; or &quot;... No ...&quot; then you could use yes or no, they sound different. But that means that the operator answering would have to press the button, count in their head to three, say YES, then count in their head to three, finally releasing the button. However if that operator was distracted, and didn't wait, or if the operator was out sick and the new guy didn't know the protocol, or there was a large network of people asking the question all with slightly different protocols, now &quot;...Yes...&quot; doesn't work as well. &lt;/p&gt;&#xA;" OwnerUserId="12262" LastEditorUserId="34829" LastEditDate="2018-10-10T14:12:40.083" LastActivityDate="2018-10-10T14:12:40.083" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="25758" PostTypeId="2" ParentId="25650" CreationDate="2016-03-02T22:25:48.753" Score="8" Body="&lt;p&gt;You raise an interesting question, and I assume you refer to flying near the poles using a lightly equipped general aviation aircraft. Airliners or jets usually have inertial navigation equipment that is working autonomously and will not be affected by pole proximity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several procedures could be taken in a general aviation aircraft to improve situational awareness:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You need indeed to deslave the HSI from the magnetic slaving transmitter in order to use it as a directional gyro manually slaved (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/24133/how-does-a-horizontal-situation-indicator-hsi-work/24264#24264&quot;&gt;How does a horizontal situation indicator (HSI) work?&lt;/a&gt;). The directional gyro will have to be realigned manually regularly to compensate for precession (astronomical precession is 15°/hour at the pole, to the right at North pole, to the left at South pole).&lt;/li&gt;&#xA;&lt;li&gt;Don't forget it is still possible to use astronomical navigation if you are in VFR conditions and able to see stars (at night) or the Sun (during day). This will not be very accurate but a precision better than 5 to 10 degrees could be reached without needing a sextant. Computing your location only from star positions is a complex operation, but it is rather easy to find out aircraft true heading thanks to the Sun or major stars relative position from aircraft nose. You could use this heading to manually realign your unslaved HSI/directional gyro.&lt;/li&gt;&#xA;&lt;li&gt;Regarding GPS, it is strongly advised to check in advance GPS coverage near the pole using RAIM prediction function, either from the onboard GPS or using web servers. This will allow you to check the coverage should be assured according GPS satellite locations relative to your position (an outage is always possible). When flying in such remote locations I always bring with me a portable standalone GPS unit, in addition to panel mounted GPS.&lt;/li&gt;&#xA;&lt;li&gt;Standard navigation (keeping track of position thanks to heading and clock) of course should be used and near coasts you could cross-check your computed position using landmarks, but above ice caps you will have few or no landmarks.&lt;/li&gt;&#xA;&lt;li&gt;If you are lucky enough to have an inertial navigation platform on board, your position will be kept rather accurately independently of any other input, with an error of the order of 10 NM after 7 hours of flight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The main issue you will encounter in a general aviation aircraft flying near the pole is their endurance is often limited, regulatory fuel reserves are higher than usual, airports are few and far apart, alternates may close quickly due to quickly changing weather conditions. This means that when you fly or are ferrying an aircraft in those regions, you could definitely not afford to get lost or not to be sure of your position.&lt;/p&gt;&#xA;" OwnerUserId="12957" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-03-04T15:31:48.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25759" PostTypeId="2" ParentId="25746" CreationDate="2016-03-02T22:51:04.850" Score="6" Body="&lt;p&gt;An aircraft is never &quot;Required&quot; to be pressurized. The only reason to pressurize an aircraft is profit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No one would ever buy an un-pressurized Phenom 100 or B777, but there is nothing stopping you from building one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressurized aircraft are built because they can generate a profit for the manufacturer. Any aircraft can be made with pressurization but it comes with a price. If marketing determines it will sell, they will build it with pressurization. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can look at pressurization as simply a comfort option. A comfort option that comes with a price.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There have been many cases of aircraft being built in both pressurized and un-pressurized versions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cessna 402 and 414, Cessna 335 and 340, Cessna 210 and P210, Piper PA-31 Navajo and PA-31P Pressurized Navajo are all examples of the same aircraft built in both pressurized and un-pressurized versions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In all these examples the un-pressurized aircraft can fly well above 20,000' but is generally operated at lower altitudes due to the inconvenience of using supplemental oxygen. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-02T23:30:26.803" LastActivityDate="2016-03-02T23:30:26.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25760" PostTypeId="1" CreationDate="2016-03-03T00:23:23.600" Score="-4" ViewCount="445" Body="&lt;p&gt;I recently learned that the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased. So I am confused about what is the point of the slope on top of the airfoil. The Wright brothers' airfoil was flat, but still had the slight slope to it, and now modern aircraft have a huge slope to them. So what is the reason for the slope?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastEditorUserId="12220" LastEditDate="2016-03-03T00:38:21.473" LastActivityDate="2019-04-12T19:50:55.180" Title="Why do modern aircraft have a slope on top of the airfoil?" Tags="&lt;airfoil&gt;" AnswerCount="3" CommentCount="2" ClosedDate="2016-03-03T13:33:52.340" ContentLicense="CC BY-SA 3.0" />
  <row Id="25761" PostTypeId="2" ParentId="25760" CreationDate="2016-03-03T00:52:37.290" Score="-2" Body="&lt;p&gt;The slope (known as the camber) is for better stalling characteristics so that the turbulent flow separates from the airfoil slowly instead of suddenly because the curve allows the air more surface to stick on at the AoA increases to a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This stall diagram shows how the cambered wing performs in a stall:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/02QSa.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/02QSa.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/intro-wings.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, according to the gas laws, the air in higher pressure moves slower than air in low pressure. (P1*V1 = P2*V2) The air on the upper surface does move faster at higher AoAs due to the lower pressure created by the AoA.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-03T00:52:37.290" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25762" PostTypeId="1" AcceptedAnswerId="25793" CreationDate="2016-03-03T01:02:19.210" Score="5" ViewCount="871" Body="&lt;p&gt;In this awesome video, shot at the &quot;Mach Loop&quot; in Wales, F-15Cs fly down the valley, then cross a ridge very low to the ground. While it's difficult to tell from the video just how low they really are, they seem to be &lt;em&gt;fairly&lt;/em&gt; close. How much effect on flight characteristics do the pilots feel as the ground comes up to meet them, then falls away?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/JultKcPcKjk?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To clarify a couple of points from the comments, I'm interested in &lt;em&gt;any&lt;/em&gt; effects on flight control that are caused by flying &lt;em&gt;fairly&lt;/em&gt; low over that ridge and through the valley (&lt;sub&gt;to grandmother's house we go&lt;/sub&gt;).&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2016-03-05T14:01:29.563" LastActivityDate="2018-12-30T11:11:09.443" Title="How much effect does the ground have on flight control when flying low?" Tags="&lt;aerodynamics&gt;&lt;flight-training&gt;&lt;ground-effect&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25763" PostTypeId="1" AcceptedAnswerId="25766" CreationDate="2016-03-03T01:23:15.993" Score="6" ViewCount="1390" Body="&lt;p&gt;I always see images with a runway and a rectangular flight path over it and ask myself why do the pilots take off, fly around the runway and get back and land, what is the purpose of doing that: take off, fly parallel to the runway and land? Am I missing something?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PNDPz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PNDPz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bvartcc.com/Site/Communities/PilotRatingsProgram/VFR1.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="62" LastEditDate="2016-03-06T03:09:33.453" LastActivityDate="2016-03-06T03:09:33.453" Title="What is the purpose of a Traffic Pattern?" Tags="&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25764" PostTypeId="2" ParentId="25762" CreationDate="2016-03-03T01:51:32.460" Score="3" Body="&lt;p&gt;Low is of course a relative term but at a sufficiently low altitude a plane will physically experience &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)&quot; rel=&quot;nofollow&quot;&gt;ground effect&lt;/a&gt;. This generally occurs with in one wing spans length from the ground and manifests its self as reduced drag on the airframe, lower stalling speed and a general floating feeling.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this specific case the planes appear to be flying low in a relatively mountainous area. The pilots may experience certain &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/tips_on_mountain_flying.pdf&quot; rel=&quot;nofollow&quot;&gt;mountain related wind conditions&lt;/a&gt; while flying this low as well. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-03-03T01:51:32.460" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25765" PostTypeId="1" CreationDate="2016-03-03T02:04:30.317" Score="12" ViewCount="1116" Body="&lt;p&gt;If you are not aware, &lt;a href=&quot;http://www.fly-sea.com/charts/EGKK.pdf&quot; rel=&quot;noreferrer&quot;&gt;London Gatwick&lt;/a&gt; (aka EGKK) has a setup with a primary air carrier runway and a backup runway immediately next to it, such that only one runway can be used at a time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main runway 8R/26L (South) has full HIALS (ALSF-2 in FAA parlance) with CAT III ILS as well as RNAV (LNAV/VNAV, no SBAS/LPV) and plated SRA non-precision approaches; however, the backup runway 8L/26R (North) only has RNAV and SRA approaches, and no ALS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similar runway configurations in the US (KEWR aka Newark Int'l is similar save for having a crosswind runway) allow what is called a sidestep ILS procedure, where the main ILS is flown to higher (nonprecision) minima and then a maneuver is executed on short final to &quot;slide&quot; over to the other runway after visual contact with both runways has been achieved. From AIM 5-4-19:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5−4−19. Side−step Maneuver&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; ATC may authorize a standard instrument&#xA;  approach procedure which serves either one of&#xA;  parallel runways that are separated by 1,200 feet or&#xA;  less followed by a straight−in landing on the adjacent&#xA;  runway.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; Aircraft that will execute a side−step maneuver&#xA;  will be cleared for a specified approach procedure&#xA;  and landing on the adjacent parallel runway.&#xA;  Example, “cleared ILS runway 7 left approach,&#xA;  side−step to runway 7 right.” Pilots are expected to&#xA;  commence the side−step maneuver as soon as&#xA;  possible after the runway or runway environment is&#xA;  in sight. Compliance with minimum altitudes&#xA;  associated with stepdown fixes is expected even after&#xA;  the side−step maneuver is initiated.&#xA;  NOTE−&#xA;  Side−step minima are flown to a Minimum Descent&#xA;  Altitude (MDA) regardless of the approach authorized.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;c.&lt;/strong&gt; Landing minimums to the adjacent runway will&#xA;  be based on nonprecision criteria and therefore higher&#xA;  than the precision minimums to the primary runway,&#xA;  but will normally be lower than the published circling&#xA;  minimums.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why has the UK not published similar minima for Gatwick's ILS?  The existing OCHs for the secondary runway RNAV approaches are in the 650' range -- if the Newark ILS sidestep minima are any indication, it'd be possible to obtain lower minima for a sidestep approach to the EGKK secondary runway than are currently available from the RNAV or SRA approaches, and it would require no new navaids to be put into service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are sidestep approaches verboten in JAR-land? Is there some terrain or obstacle factor that I'm not seeing that makes a sidestep ILS approach into EGKK problematic or not desirable relative to the current RNAV approaches to the secondary runway?  Or can the ICAO/CAA format for approach plates not represent sidestep minima?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="3825" LastEditDate="2016-03-03T23:07:23.397" LastActivityDate="2017-06-05T11:44:52.573" Title="Why are sidestep ILS minima not used in EASA-land? (specific example: EGKK)" Tags="&lt;easa-regulations&gt;&lt;ils&gt;&lt;iaps&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25766" PostTypeId="2" ParentId="25763" CreationDate="2016-03-03T02:14:17.510" Score="10" Body="&lt;p&gt;I think there are two parts to your question: why do traffic patterns exist, and why do people fly around them in circles?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, a huge amount of aviation effort goes into avoiding collisions, for obvious reasons. One part of that is making everyone behave as predictably as possible, so that you know what to expect from other pilots and where to look for aircraft near you. That's why there are regulations on airspace, altitudes, speeds and all sorts of other things that affect how and where aircraft fly: if everyone is following the same rules then life is much easier. For example, if you're driving down a one-way street in your car, you can be (reasonably) confident that you won't meet someone coming the other way, and drive accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because aircraft operate very closely together around airports, there's a higher risk of collisions and it's especially important to have very clear rules for how and where pilots take off, approach the runway and land. The traffic pattern is the aviation equivalent of road markings: it 'shows' where you should fly in order to fit in with everyone else, fly in the same direction, be visible to others, and generally be as obvious and predictable as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, why do pilots take off, fly around the pattern and land again? Usually, because it's a great training exercise. In the process of going around the pattern you have to perform multiple important maneuvers and tasks, including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Taking off&lt;/li&gt;&#xA;&lt;li&gt;Climbing out in a controlled, precise way&lt;/li&gt;&#xA;&lt;li&gt;Making coordinated turns&lt;/li&gt;&#xA;&lt;li&gt;Managing airspeed&lt;/li&gt;&#xA;&lt;li&gt;Operating key aircraft systems like the landing gear, flaps, lights etc.&lt;/li&gt;&#xA;&lt;li&gt;Using checklists&lt;/li&gt;&#xA;&lt;li&gt;Working with ATC (if it's a controlled airport)&lt;/li&gt;&#xA;&lt;li&gt;Descending in a controlled, stable approach to land&lt;/li&gt;&#xA;&lt;li&gt;Landing&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since taking off and landing are often considered the riskiest parts of a flight, doing pattern work is a great way to get as much practice as quickly and easily as possible. For example, I just got back from doing some night pattern work: I did 10 takeoffs and landings in about 35 minutes. That packs a lot of practice into a short amount of time, which is useful for everyone but especially for student pilots.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-03T02:14:17.510" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25767" PostTypeId="2" ParentId="25746" CreationDate="2016-03-03T02:41:18.570" Score="0" Body="&lt;p&gt;Taking a broader view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the &quot;partial pressure&quot; of oxygen (that is the overall pressure of the gas mixture multiplied by the propotion of oxygen in it) in the gas mixture people are breathing drops too low then people will suffer serious and potentially life-threatening medcial problems. We need to prevent that happening. There are several options for preventing it each with different disadvantages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One option is to simply fly low enough. This is a common soloution for low speed travel but it doesn't work well for high speed flight. It may also cause issues if you need to fly over mountains.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A second option is to have everyone use supplemental oxygen delivered through some form of mask (possiblly a full face mask, possiblly a non-sealed mask like the one in Daves picture). This is an option for military planes and some GA stuff but I don't think it would work too well for airliners or buisness jets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The third option is to pressurise the cabin. This allows you to fly at high altitudes where fast flight is practical while providing an environment where people don't have to tether themselves to oxygen masks. The downside is that your fuselage is now a pressure vessel and worse it's a pressure vessel that experiances frequent pressure cycles. As a result pressurised airplanes require far more careful design, construction and maintinance then unpressurised ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fourth theoretical option would be to use an oxygen enriched atmosphere in the cabin. Afaict this is not used in avaition, I don't know exactly why but I would guess a combination of fire risks and the difficulty of supplying enough oxygen.&lt;/p&gt;&#xA;" OwnerUserId="11774" LastActivityDate="2016-03-03T02:41:18.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25768" PostTypeId="2" ParentId="25760" CreationDate="2016-03-03T02:58:17.017" Score="-2" Body="&lt;p&gt;You are wrong about the air under the wing travelling faster. It is the air travelling over the top of the wing that is faster. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;slope&quot; is actually called Camber. Camber makes the air flowing over the wing change direction and this causes low pressure and that results in lift. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M2GMy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M2GMy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-03T12:51:49.303" LastActivityDate="2016-03-03T12:51:49.303" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25769" PostTypeId="2" ParentId="25762" CreationDate="2016-03-03T03:19:39.507" Score="1" Body="&lt;p&gt;Ground effect is defined:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...the increased lift (force) and decreased aerodynamic drag that an aircraft's wings generate when they are close to a fixed surface.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)&quot; rel=&quot;nofollow&quot;&gt;Source: Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect is that the aerodynamic drag is decreased and subsequently lift is increased giving the ability for the aircraft to fly at a lower speed than normally it could. It is also a reason why overloaded planes can get off the ground but then stall as soon as they try to get some altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ground effect happens when the aircraft is at an altitude that is less than the wingspan of the aircraft. For an F-15, this means that they would need to be within 43' of the ground. Having watched the video its difficult to determine the exact altitude but I'd hazard to say that they are more than 50' off the turf.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the other part of your question is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How much effect on flight characteristics do the pilots feel as the ground comes up to meet them, then falls away?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It can be significant, especially in low-wing aircraft. Speaking from a GA perspective, the controls become lighter and the airplane floats or doesn't want to touch the ground. However the composition of the surface has a large effect on this. Soft earth or water has a lesser effect than a hard surface like pavement. Passing over peaks at 250+ mph is probably going to have little effect whereas coming in to land will be much more noticeable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few fighter pilots that hang around here that may be able to tell you what it feels like in a fly-by-wire aircraft, but in a cable and pulley system its definitely noticeable. So much so that it can make an otherwise un-flyable aircraft fly. There are aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_vehicle&quot; rel=&quot;nofollow&quot;&gt;designed to operate solely in ground effect&lt;/a&gt; and has been &lt;a href=&quot;http://www.ntsb.gov/news/events/Pages/2012_Roswell_NM_BMG.aspx&quot; rel=&quot;nofollow&quot;&gt;a factor in aircraft crashes&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-03T21:46:19.683" LastActivityDate="2016-03-03T21:46:19.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25770" PostTypeId="2" ParentId="3573" CreationDate="2016-03-03T03:37:05.997" Score="17" Body="&lt;p&gt;It's not really bad at all.  How do we know?  Because the ATC didn't intervene or question you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What emerges for me out of this report is that you need a new CFI. Getting angry at a student's innocent mistake is bad.   In particular if it is not something you've been cautioned about before (have you?).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Communicating angry feedback by text is even worse. A good CFI would have waited till they had a chance to speak to you, and started with asking you what happened, not started with an attack on you.&lt;/p&gt;&#xA;" OwnerUserId="945" LastActivityDate="2016-03-03T03:37:05.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25771" PostTypeId="1" CreationDate="2016-03-03T05:47:40.450" Score="1" ViewCount="855" Body="&lt;p&gt;What is the function of the hole at the rear of a plane?&#xA;I searched online but didn't get a satisfying answer.&lt;/p&gt;&#xA;" OwnerUserId="13761" LastEditorUserId="3201" LastEditDate="2016-03-03T09:46:27.070" LastActivityDate="2016-03-03T09:46:27.070" Title="What is the function of the hole at the rear of the airplane?" Tags="&lt;aircraft-design&gt;&lt;apu&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-03-03T08:18:45.210" ContentLicense="CC BY-SA 3.0" />
  <row Id="25772" PostTypeId="2" ParentId="25771" CreationDate="2016-03-03T06:04:51.643" Score="2" Body="&lt;p&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/d/d2/A380_APU_P1230093.jpg/500px-A380_APU_P1230093.jpg&quot; alt=&quot;APU&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one? It's the APU(auxiliary power unit)'s exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An auxiliary power unit (APU) is a device on a vehicle that provides energy for functions other than propulsion. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The primary purpose of an aircraft APU is to provide power to start&#xA;  the main engines. Turbine engines must be accelerated to a high&#xA;  rotational speed to provide sufficient air compression for&#xA;  self-sustaining operation. Smaller jet engines are usually started by&#xA;  an electric motor, while larger engines are usually started by an air&#xA;  turbine motor. Before the engines are to be turned, the APU is&#xA;  started, generally by a battery or hydraulic accumulator. Once the APU&#xA;  is running, it provides power (electric, pneumatic, or hydraulic,&#xA;  depending on the design) to start the aircraft's main engines.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Auxiliary_power_unit&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Auxiliary_power_unit&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13818" LastActivityDate="2016-03-03T06:04:51.643" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25773" PostTypeId="2" ParentId="25760" CreationDate="2016-03-03T06:52:26.700" Score="-1" Body="&lt;p&gt;First of all, wherever you learned that, &lt;blockquote&gt;&quot;...the pressure on the bottom of the wing is increased, and air moves faster on the bottom part of the wing. The speed of the air on top of the wing is not increased.&quot;&lt;/blockquote&gt; It is wrong, and citations would be useful, if only to educate the owner of that website.&lt;br&gt;&lt;br&gt;A wing provides lift by imparting momentum to the air through which it passes equal to the airplane's weight. If the wing is cambered, it imparts more acceleration to the air through which it passes. (i.e. the air coming off the trailing edge has a faster downward velocity than compared to a non-cambered airfoil of equal area), thus making the wing more efficient for its area. It also affects things like stall speed.&lt;/p&gt;&#xA;" OwnerUserId="8156" LastEditorUserId="8156" LastEditDate="2019-04-12T19:50:55.180" LastActivityDate="2019-04-12T19:50:55.180" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25774" PostTypeId="1" CreationDate="2016-03-03T13:06:54.103" Score="9" ViewCount="5401" Body="&lt;p&gt;Many Aircraft engines mix the bypass air with the core gases before exhausting to atmospheric pressure through a propelling nozzle. However, some do not mix and have separate nozzles for the flow of each. What are the advantages and disadvantages of each?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: I hope that I am clear now. Sorry if the question wasn't clear earlier. &lt;/p&gt;&#xA;" OwnerUserId="13652" LastEditorUserId="12720" LastEditDate="2016-03-03T21:23:27.763" LastActivityDate="2018-07-16T21:12:41.083" Title="What are the advantages and disadvantages of mixing the bypass flow with the core flow?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;engine&gt;&lt;engine-design&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25775" PostTypeId="2" ParentId="25554" CreationDate="2016-03-03T14:57:38.823" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/141.41&quot; rel=&quot;nofollow&quot;&gt;14 CFR Part 141, Chapter 41&lt;/a&gt; &lt;em&gt;Flight simulators, flight training devices, and training aids&lt;/em&gt;. Requirements for a FTD:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Be a full-size replica of instruments, equipment panels, and&#xA;  controls of an aircraft, or set of aircraft, in an open flight deck&#xA;  area or in an enclosed cockpit, including the hardware and software&#xA;  for the systems installed that is necessary to simulate the aircraft&#xA;  in ground and flight operations;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The important mention is it must be a full-size replica of controls and panels. This doesn't apply for an ATD (see definition in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-136A.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 61-136A&lt;/a&gt;, appendix 2).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.fredonflying.com/Articles/IFR_Refresher/1104-Sorting-the-Simulators.pdf&quot; rel=&quot;nofollow&quot;&gt;Sorting the simulators&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://generalaviationnews.com/2015/02/12/faa-withdraws-atd-rule/&quot; rel=&quot;nofollow&quot;&gt;FAA withdraws ATD rule&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-03-03T14:57:38.823" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25778" PostTypeId="1" AcceptedAnswerId="25779" CreationDate="2016-03-03T15:42:23.687" Score="2" ViewCount="9101" Body="&lt;p&gt;What are the pros and cons of a monoplane, biplane and triplane design; aerodynamics, efficiency, etc.?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-03-03T16:42:18.207" Title="What are the advantages and disadvantages of a monoplane, biplane and triplane?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ClosedDate="2016-03-03T18:53:47.927" ContentLicense="CC BY-SA 3.0" />
  <row Id="25779" PostTypeId="2" ParentId="25778" CreationDate="2016-03-03T16:42:18.207" Score="6" Body="&lt;p&gt;One way to look at the differences between them is by looking at the effects of having multiple wings.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Having multiple wings means that the same aircraft can produce more lift for the same wingspan, as they have a greater wing area. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, the biplanes and triplanes have lesser wing loading, which results in shoter to/landing and lower stall speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The shorter wingspan results in reduced roll inertia and roll damping, which results in better roll rates in the bi- and tri- planes. This improved maneuverability was the reason for the surge in triplane designes during WWI.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Due to interference effects, the bi- and tri- planes actually require higher wing area to produce the required lift. Also, the drag is also higher than the monoplane, which gets more pronounced as the speed increases.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The main reason for the use of bi- and tri- planes was that they provided the required strength for the type of airfoils used. As high strength materials became available, this mattered less and the aerodynamic disadvantage of the biplane (and triplane) designs came into fore. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic advantage of the monoplane along with improvements in materials used has made the monoplane the de-facto standard except for certain specialised applications (like low speed aerobatics)&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-03T16:42:18.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25781" PostTypeId="1" AcceptedAnswerId="25783" CreationDate="2016-03-03T18:01:38.400" Score="6" ViewCount="1376" Body="&lt;p&gt;It is said that wake turbulence occurs when an aircraft generates lift and there is no wake turbulence after touch down or before take off. That's how we avoid wake turbulence. However, I've thought we have lift while on landing roll or take off roll because there is the angle of incidence and at least a certain amount of speed, just not enough lift to be airborne. Based on my idea, I don't really understand why does wake turbulence suddenly disappear like a magic when we land. &#xA;Can someone explain this please?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="62" LastEditDate="2016-03-03T18:09:37.490" LastActivityDate="2016-03-03T23:05:31.610" Title="Why there is no wake turbulence right after touch down or before rotation?" Tags="&lt;aerodynamics&gt;&lt;wake-turbulence&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25782" PostTypeId="1" AcceptedAnswerId="25786" CreationDate="2016-03-03T18:09:14.630" Score="6" ViewCount="614" Body="&lt;p&gt;I was watching &lt;a href=&quot;https://m.youtube.com/watch?v=IBeZoyAs_Cw&quot; rel=&quot;nofollow&quot;&gt;Mayday Varig Flight 254&lt;/a&gt; and at minute 38 it said that some passengers noticed that the plane was flying in the wrong direction. This accident &lt;a href=&quot;https://en.wikipedia.org/wiki/Varig_Flight_254&quot; rel=&quot;nofollow&quot;&gt;took place in 1989&lt;/a&gt;, so my question is: without 'modern' aids like GPS, smartphones, in-flight entertainment system maps etc., can a passenger really notice where the aircraft is heading to?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I suggest you watch that minute of the video if you have the time. It will help to understand the question.)&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="62" LastEditDate="2016-03-03T19:39:40.870" LastActivityDate="2017-09-05T01:55:01.763" Title="Can passengers tell (without GPS etc.) where the aircraft is heading to?" Tags="&lt;commercial-aviation&gt;&lt;passenger&gt;" AnswerCount="3" CommentCount="17" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25783" PostTypeId="2" ParentId="25781" CreationDate="2016-03-03T18:35:55.770" Score="10" Body="&lt;p&gt;Well there may be vortex formation on the ground under certain conditions, but it doesn't stick around long enough to really be measured or cause trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any time a wing is producing lift it will generate a wake. This happens even if the wing generates just enough lift to make the aircraft &quot;lighter&quot; but not enough to get it off the ground: Vortices will still start to form at the wingtips, but as they begin their rotation (downward and outward) they will quickly hit the ground and be dispersed.&lt;br&gt;&#xA;If the runway were a narrow strip with the wingtips hanging out in free air you would still see vortex formation in these edge cases, but pilots generally don't like to take off on a tightrope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes also usually don't stay in that kind of edge case situation where the wing is generating lift but the wheels are still on the ground for very long: Either they're taking off (soon after the wing starts producing &lt;em&gt;some&lt;/em&gt; lift it's producing &lt;em&gt;enough&lt;/em&gt; lift and the airplane begins flying), or they're landing (within a few seconds after you touch down you've slowed to a point where the wing's lift production, and thus vortex formation, is negligible). Thus for practical purposes of wake turbulence avoidance the wake begins when the airplane rotates, and ends where it touches down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also worth noting that if you happen to be following close enough for the incipient wingtip vortices to cause trouble on the ground you'll probably be experiencing other issues (jet blast, prop blast, etc.) which will remind you that it's prudent to maintain a safe separation distance from other aircraft on the ground.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-03-03T18:35:55.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25784" PostTypeId="1" AcceptedAnswerId="25785" CreationDate="2016-03-03T18:46:36.440" Score="1" ViewCount="6394" Body="&lt;p&gt;I'm planning my cross country journey for my flight test and it seems I forgot how to calculate my indicated airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The indicated airspeed must be from the POH, right?&#xA;The the true airspeed is from the IAS and TAS correction table in the POH?&#xA;Then the ground speed is based on TAS, with the wind factored in?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm flying a mid-late 70s Cessna 172 skyhawk.&lt;/p&gt;&#xA;" OwnerUserId="13833" LastEditorUserId="64" LastEditDate="2016-03-03T19:04:34.923" LastActivityDate="2016-03-03T19:23:28.030" Title="How do you calculate indicated airspeed on a flight plan?" Tags="&lt;flight-planning&gt;&lt;airspeed&gt;&lt;performance-calculation&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25785" PostTypeId="2" ParentId="25784" CreationDate="2016-03-03T19:14:30.300" Score="5" Body="&lt;p&gt;You do not calculate indicated airspeed: It is an &lt;em&gt;indicated&lt;/em&gt; value, you read it from the airspeed indicator. (I suppose you &lt;em&gt;can&lt;/em&gt; calculate it if you really want to, but I've got no idea why you would want to do so in the context of flight planning.)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;You determine what airspeed to use for flight planning purposes using your aircraft's performance data (from the POH or other manufacturer documents): There will usually be either a chart or a table giving true airspeed as a function of power setting and density altitude.&lt;br&gt;&#xA;(&lt;em&gt;True Airspeed&lt;/em&gt; is a more useful number for planning purposes as it saves you a calculation.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VCnmb.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VCnmbm.png&quot; alt=&quot;Performance Table (Cessna style)&quot;&gt;&lt;/a&gt;  &lt;a href=&quot;https://i.stack.imgur.com/66eOe.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/66eOem.png&quot; alt=&quot;Performance Chart (Piper Style&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;When in flight you can calculate your true airspeed based on the indicated airspeed and density altitude. You can then compare this to your planned figures from the performance charts to determine if adjustments are necessary to your flight plan (ETA, Fuel use, etc.)&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-03-03T19:23:28.030" LastActivityDate="2016-03-03T19:23:28.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25786" PostTypeId="2" ParentId="25782" CreationDate="2016-03-03T20:56:52.153" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;can a passenger really notice where the aircraft is heading to?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A wide variety of observable phenomena and general attentiveness can lead to an approximate understanding of which direction the aircraft is heading in.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passengers can rely on visibly observed phenomena such as stars, moon, sun, ground topology, or major landmarks (interstates, cities, facilities etc.). General familiarity with flight routes and runways, coupled with attentiveness to significant changes in roll, pitch, and yaw can bolster an understanding of the flight's direction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Items such as a compass (built into Casio calculator watches?) could also be used to get an approximation of direction. They may be affected by other instrumentation and mechanical features along with being really cheap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some passengers will be able to note which runway they took off from and a divergence from a typical path. While still ascending they can more easily notice landmarks that are likely familiar, and recognize that no significant change in direction has happened since orienting themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible too that cognitive bias may be another explanation. The media, and documentaries like this, seem to embrace an event as predictive or accurate despite a long history of inaccuracy or patterned behavior. That passenger who makes 98% incorrect assertions of plane direction is only recorded or listened to after the fact and appears to be 100% accurate in their vastly under sampled assertion set. How does it go? A broken clock is right twice a day?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, thanks to all the comments, tried to cover most of those notes/ideas here.&lt;/p&gt;&#xA;" OwnerUserId="11474" LastEditorUserId="11474" LastEditDate="2016-03-03T21:31:56.830" LastActivityDate="2016-03-03T21:31:56.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25788" PostTypeId="2" ParentId="25685" CreationDate="2016-03-03T21:55:11.847" Score="1" Body="&lt;p&gt;In my airforce this is also a useful technique that is thought to assist in handling emergency situations, at least initially. Often it would be followed by other models to assist in dealing with the emergency. It reminds you not to get so distracted by &quot;handling the emergency&quot; that you end up flying into the ground or not routing to a safe area to land or eject. Once you have control of the situation communicate your problem and intentions to ATC who can assist and/or get emergency vehicles on standby. So similar to the previous answers but with more emphasis on an emergency situation. &lt;/p&gt;&#xA;" OwnerUserId="13750" LastEditorUserId="13750" LastEditDate="2016-03-03T22:03:57.057" LastActivityDate="2016-03-03T22:03:57.057" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25790" PostTypeId="1" AcceptedAnswerId="25792" CreationDate="2016-03-03T22:50:55.497" Score="1" ViewCount="440" Body="&lt;p&gt;As a ground observer, how can you tell if an aircraft is climbing or descending?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-03T22:59:45.947" LastActivityDate="2016-03-03T23:14:31.067" Title="How to know if an aircraft is climbing or descending?" Tags="&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25791" PostTypeId="2" ParentId="25781" CreationDate="2016-03-03T23:05:31.610" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8877/how-does-an-aircraft-form-wake-turbulence/8882#8882&quot;&gt;Wake turbulence&lt;/a&gt; is related to the amount of lift produced. This in turn is proportional to the angle of attack of the wing. Before &lt;a href=&quot;https://aviation.stackexchange.com/questions/12892/how-much-lift-do-planes-produce-before-rotation&quot;&gt;take-off rotation&lt;/a&gt; the wing produces little lift, so the effect of wake turbulence is small. &lt;a href=&quot;https://aviation.stackexchange.com/questions/311/what-is-ground-effect&quot;&gt;Ground effect&lt;/a&gt; will weaken the wake further, but it would technically be wrong to say that no wake turbulence is produced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The strength of the wake turbulence of a flying aircraft is proportional to the mass of the aircraft and inverse with airspeed squared. This means that the turbulence gets stronger while the aircraft descends and decelerates, and wake turbulence reaches a peak right before touchdown. With the wing close to the ground, ground effect will weaken the turbulence, so when the wheels touch the ground the intensity of the wake is maybe two thirds of its free flight strength at the same speed. Only when the aircraft derotates (the process when pitch attitude is reduced until the nose wheel touches the ground), the wake turbulence will be significantly reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After derotation the lower &lt;a href=&quot;https://en.wikipedia.org/wiki/Zero-lift_axis&quot; rel=&quot;nofollow noreferrer&quot;&gt;zero-lift angle&lt;/a&gt; due to the flap deflection for landing will let the wing produce more lift at the same speed than in case of the aircraft with flaps set for take-off. Again, ground effect and extending spoilers or wing-mounted speed brakes reduces the wake (with flaps down the ground effect is even stronger), but here it would be even more incorrect to say that there is no wake turbulence. It is only much weaker than in flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-03T23:05:31.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25792" PostTypeId="2" ParentId="25790" CreationDate="2016-03-03T23:12:45.753" Score="5" Body="&lt;p&gt;Listen. Climbing aircraft need more thrust, so the noise they produce is related to their vertical speed. Since most excess performance is available at low speed, a slowly flying aircraft producing a lot of noise will most likely be climbing. Once you gain a little experience, the pitch of the engine and propeller sound of piston-engined aircraft will be a very good indicator of their thrust setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't work for gliders. Here you need to wait to be sure if they are climbing or descending. Only when you see that the glider flies with speed brakes extended you can be sure instantly that it is descending.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-03T23:14:31.067" LastActivityDate="2016-03-03T23:14:31.067" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25793" PostTypeId="2" ParentId="25762" CreationDate="2016-03-03T23:27:18.393" Score="10" Body="&lt;p&gt;At the high speed of the F-15s in the video ground effect is almost negligible. Ground effect is about the restriction of downwash by the ground, and at high speed and air density downwash is rather small. Also, the duration of close proximity to the ground is too short for ground effect to fully develop.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest effect will be air turbulence. Since air will neither flow into the ground nor out of it, the vertical speed of atmospheric turbulence is greatly reduced when flying close to the ground. Also, the scale of turbulence will get smaller with proximity to the ground. While gusts may rock your wings when flying high, at very low altitude (less than one wingspan) the turbulence will average out over the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying over a ridge, any wind speed component perpendicular to the ridge line will mean updrafts on the windward side of the ridge and downdrafts on the leeward side. &lt;strong&gt;This&lt;/strong&gt; will be the strongest effect in this particular case of F-15s flying over a ridge at Mach 0.7 to 0.9.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now back to that ground effect meme which seems to find wide agreement here: Ground effect is a stationary process which is strongest at low speed, when the downwash behind the wing is strong. In the case shown here, the aircraft is only momentarily in close proximity to the ground. The pressure field around the aircraft will never reflect that proximity because it is gone before the aerodynamics could start to react. This is completely instationary aerodynamics, and air, having mass, will take some time to respond. However, it is never given this time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-12-30T11:11:09.443" LastActivityDate="2018-12-30T11:11:09.443" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="25794" PostTypeId="1" AcceptedAnswerId="25809" CreationDate="2016-03-03T23:40:32.583" Score="2" ViewCount="4590" Body="&lt;p&gt;First off, here is my understanding: I'm primarily concerned with retrofit aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A number of Asian countries (and Australia) already require ADS-B to DO-260A standard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The European mandate is set for June 7, 2020 (DO-260B).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The North American (FAA) mandate is set for January 1, 2020 (DO-260B).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I correct in my assumptions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the deadlines, what are the operational limitations (assuming the aircraft is equipment with DO-260A)? Is the aircraft banned from the airspace completely or is it still possible to operate but get undesirable routing (such as low altitude or positioning)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is involved in upgrading to DO-260B? What are the differences between the standards?&lt;/p&gt;&#xA;" OwnerUserId="13836" LastActivityDate="2016-03-04T09:33:01.757" Title="What are the operational limitations on ADS-B DO-260A (as compared to DO-260B)?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airspace&gt;&lt;easa-regulations&gt;&lt;ads-b&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25795" PostTypeId="1" AcceptedAnswerId="25796" CreationDate="2016-03-03T23:45:26.250" Score="10" ViewCount="3244" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uGzcw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uGzcw.jpg&quot; alt=&quot;singapore777&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's in the desert somewhere and it has its windows and landing gear and doors covered. Why is it that? Of course, it's not in service anymore...&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Untitled-(Singapore-Airlines)/Boeing-777-212-ER/2784912/&amp;amp;sid=95a59c577a5258e799c5da51bae50628&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T14:18:41.217" LastActivityDate="2016-03-05T14:18:41.217" Title="Why is this 777 with doors and windows covered?" Tags="&lt;aircraft-storing&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25796" PostTypeId="2" ParentId="25795" CreationDate="2016-03-03T23:51:49.163" Score="13" Body="&lt;p&gt;The aircraft is in storage. The Boeing 777-212(ER) seems to operated by Singapore Airlines under &lt;a href=&quot;http://www.bloomberg.com/research/stocks/private/snapshot.asp?privcapid=1055101&quot;&gt;lease from Pembroke&lt;/a&gt; before being &lt;a href=&quot;https://www.planespotters.net/airframe/Boeing/777/28530/EI-FGT-Pembroke&quot;&gt;withdrawn from use in Dec 2014&lt;/a&gt;. After that, the aircraft is under storage at &lt;a href=&quot;https://en.wikipedia.org/wiki/Southern_California_Logistics_Airport&quot;&gt;Southern California Logistics Airport&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The windows are covered in aluminium foil for storage; however, the engines appear to be still there (which will usually be removed), which indicates that the storage was planned for only a short time. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1467" LastEditDate="2016-03-04T08:10:01.593" LastActivityDate="2016-03-04T08:10:01.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25797" PostTypeId="2" ParentId="25795" CreationDate="2016-03-03T23:52:07.497" Score="13" Body="&lt;p&gt;Currently that airplane is in storage per &lt;a href=&quot;https://www.planespotters.net/airframe/Boeing/777/28530/EI-FGT-Pembroke&quot;&gt;planespotters.net&lt;/a&gt;. The reason why it is stored in the desert is because the environment would not cause some structural damage to the airframe. All those doors and windows are covered to keep animals, dust, and even sunlight out so that they would not damage the airframe either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can read more about storing aircraft in the desert &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_boneyard&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;http://www.johnweeks.com/boneyard/&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-03T23:52:07.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25798" PostTypeId="1" AcceptedAnswerId="25799" CreationDate="2016-03-04T00:22:03.233" Score="4" ViewCount="204" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XB5io.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XB5io.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was going from Argentina to Germany and after takeoff it went over a town and then it went direct to Germany. Why did it go over the town instead of going directly to Germany?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.flightradar24.com/56.2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:01:37.760" LastActivityDate="2016-03-05T17:01:37.760" Title="Why did this departure from Buenos Aires seem to delay heading northeast?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25799" PostTypeId="2" ParentId="25798" CreationDate="2016-03-04T00:50:11.180" Score="7" Body="&lt;p&gt;It's following a &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_instrument_departure_(SID)&quot; rel=&quot;nofollow noreferrer&quot;&gt;departure procedure&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tKfwQ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tKfwQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://uvairlines.com/admin/resources/charts/SAEZ.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;chart source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The path flown matches the route described for departing Runway 11 with the La Plata 6B departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the &lt;a href=&quot;https://skyvector.com/?ll=-34.82778299304897,-58.105224601779156&amp;amp;chart=301&amp;amp;zoom=4&quot; rel=&quot;nofollow noreferrer&quot;&gt;map here&lt;/a&gt; to visually match up the described departure procedure with the flown path.&lt;/p&gt;&#xA;" OwnerUserId="6886" LastActivityDate="2016-03-04T00:50:11.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25800" PostTypeId="1" AcceptedAnswerId="25805" CreationDate="2016-03-04T01:45:48.517" Score="4" ViewCount="919" Body="&lt;p&gt;On many webpages it is said that a departure procedure will keep aircraft away from terrain and obstacles and avoid collisions. Which type of obstacles? Buildings? Towers? What is the purpose of a departure procedure? This is a follow up of &lt;a href=&quot;https://aviation.stackexchange.com/questions/25798/why-did-this-departure-from-buenos-aires-seem-to-delay-heading-northeast&quot;&gt;this question&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-27T05:07:50.670" Title="What is the purpose of a departure procedure?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25801" PostTypeId="1" CreationDate="2016-03-04T02:42:12.400" Score="5" ViewCount="18714" Body="&lt;p&gt;Is this something found in the POH? I know there is a IAS and CAS chart.&lt;/p&gt;&#xA;" OwnerUserId="13833" LastActivityDate="2020-11-27T04:07:34.893" Title="How do you convert true airspeed to indicated airspeed?" Tags="&lt;airspeed&gt;&lt;performance-calculation&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25802" PostTypeId="2" ParentId="25801" CreationDate="2016-03-04T04:47:19.857" Score="0" Body="&lt;p&gt;You read your TAS from your POH. Then you get to your CAS by using a flight computer, such as the E6-B. Then you use your POH to convert from CAS to IAS.&lt;/p&gt;&#xA;" OwnerUserId="13833" LastActivityDate="2016-03-04T04:47:19.857" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25805" PostTypeId="2" ParentId="25800" CreationDate="2016-03-04T07:26:14.223" Score="9" Body="&lt;p&gt;A major advantage is standardization. An aircraft can be given a &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_instrument_departure_%28SID%29&quot; rel=&quot;nofollow&quot;&gt;departure procedure&lt;/a&gt;, and assuming everything goes to plan, everyone involved will be on the same page as to what is going to happen. When air traffic control instructs an aircraft to fly a departure procedure, a large volume of information (e.g. climb to this altitude, turn this way, turn that way, etc...) can be communicated just by giving the name of the procedure. This is far more convenient and predictable for both the crew and controllers than giving every instruction individually. This allows controllers to focus on preventing conflicts and dealing with abnormal situations rather than issuing routine instructions, and it reduces the risk those instructions may be miscommunicated or misunderstood. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The procedure itself will have been developed by specialists based on all sorts of criteria, among them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstacle clearance. This can be anything from the huge mountain range near the airport to buildings to towers to anything else. The procedure can be designed with a required minimum rate of climb, and pilots can ensure they are able to meet that requirement to climb over any obstacles. Obstacles might also be virtual, such as restricted areas for military purposes.&lt;/li&gt;&#xA;&lt;li&gt;Noise abatement. Communities in the vicinity of airports often have noise complaints. Departure procedures can be designed to direct aircraft away from noise sensitive areas. &lt;/li&gt;&#xA;&lt;li&gt;Traffic flow. Near a busy airport, large numbers of aircraft are maneuvering at low altitudes. Standardizing departure and arrival flows along certain corridors allows air traffic control to deal with aircraft moving in predictable ways and avoids potential conflict between different aircraft. Departure procedures help ensure separation between arriving and departing aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Regional traffic flows. In congested airspace where several busy airports are located in close proximity, procedures can be developed to ensure that traffic to and from each airport are kept separated. A good example is the busy airspace around New York City, where &lt;a href=&quot;http://www.aero-news.net/index.cfm?do=main.textpost&amp;amp;id=c729106f-ae43-4406-86a8-59225a983513&quot; rel=&quot;nofollow&quot;&gt;complicated departure and arrival procedures&lt;/a&gt; are used to separate traffic into the region's airports.&lt;/li&gt;&#xA;&lt;li&gt;Winds. Different runways may be used depending on wind conditions. There may be different departure procedures available for different runway configurations and/or universal departure procedures that have different instructions depending on the runway used.&lt;/li&gt;&#xA;&lt;li&gt;Navigational aids. While modern &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_navigation&quot; rel=&quot;nofollow&quot;&gt;RNAV&lt;/a&gt; procedures are now available, traditional departure procedures guide aircraft from the runway through routes navigable through NAVAIDS like &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow&quot;&gt;VORs&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-directional_beacon&quot; rel=&quot;nofollow&quot;&gt;NDBs&lt;/a&gt; onto established &lt;a href=&quot;https://en.wikipedia.org/wiki/Airway_%28aviation%29&quot; rel=&quot;nofollow&quot;&gt;airways&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course, an aircraft flying a departure procedure can always be given instructions to deviate from that procedure if it becomes necessary, such as for other traffic. If conditions permit, it's also possible for a controller to give a &quot;shortcut&quot; by circumventing part of the procedure, perhaps by turning early toward the next waypoint on the flight's filed route.&lt;/p&gt;&#xA;" OwnerUserId="5568" LastEditorUserId="5568" LastEditDate="2016-04-27T05:07:50.670" LastActivityDate="2016-04-27T05:07:50.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25806" PostTypeId="1" AcceptedAnswerId="25808" CreationDate="2016-03-04T08:03:51.750" Score="7" ViewCount="34510" Body="&lt;p&gt;Do CAVOK (ceiling and visibility okay) and CAVU (ceiling and visibility unlimited) have formal definitions worldwide?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uUD6d.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uUD6d.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;CAVOK, source: &lt;a href=&quot;http://www.formercaptain.ca/category/arcadia-flies-again/&quot; rel=&quot;nofollow noreferrer&quot;&gt;formercaptain.ca&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they used in ATC communications?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-09-18T05:44:31.110" LastActivityDate="2018-12-08T15:41:39.073" Title="What is the exact meaning of CAVOK and CAVU? How are they used by pilots and ATC?" Tags="&lt;air-traffic-control&gt;&lt;weather&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25807" PostTypeId="2" ParentId="25806" CreationDate="2016-03-04T09:04:41.023" Score="7" Body="&lt;p&gt;&lt;a href=&quot;https://www.fltplan.com/abbreviations.htm&quot; rel=&quot;noreferrer&quot;&gt;CAVU&lt;/a&gt; means: &quot;CLEAR OR SCATTERED &lt;strong&gt;C&lt;/strong&gt;LOUDS &lt;strong&gt;A&lt;/strong&gt;ND &lt;strong&gt;V&lt;/strong&gt;ISIBILIY &lt;strong&gt;U&lt;/strong&gt;NLIMITED (GREATER THAN TEN MILES)&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.fltplan.com/abbreviations.htm&quot; rel=&quot;noreferrer&quot;&gt;CAVOK&lt;/a&gt; means: &quot;&lt;strong&gt;C&lt;/strong&gt;LOUD &lt;strong&gt;A&lt;/strong&gt;ND &lt;strong&gt;V&lt;/strong&gt;ISIBILITY &lt;strong&gt;OK&lt;/strong&gt; (METAR).&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://chesapeakesportpilot.com/wp-content/uploads/2015/03/military_wx_codes.pdf&quot; rel=&quot;noreferrer&quot;&gt;This military document&lt;/a&gt;, has a little more background: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Overseas locations may use the contraction “CAVOK” (ceiling and&#xA;  visibility OK). &lt;strong&gt;CAVOK&lt;/strong&gt; is used when there is no &lt;strong&gt;significant weather,&#xA;  the visibility is 10 km or greater, and the ceilings are greater than&#xA;  5,000 ft&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have never heard them used in verbal ATC communication, and they are &lt;strong&gt;not&lt;/strong&gt; listed in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/pcg_4-03-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt; so should not be used on the radio.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-03-04T09:33:09.650" LastActivityDate="2016-03-04T09:33:09.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25808" PostTypeId="2" ParentId="25806" CreationDate="2016-03-04T09:14:01.553" Score="10" Body="&lt;p&gt;CAVOK is formally defined in ICAO Annex 3 ( APP3-2 2.2 Use of CAVOK ) . You can hear it at the airports where there is no ATIS , when ATC communicates the weather info.&#xA;CAVU is not formally defined in Annex 3 .&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the following conditions occur simultaneously at the time of observation:&lt;/p&gt;&#xA;&lt;pre&gt;&lt;code&gt; a) visibility, 10 km or more, and the lowest visibility is not reported;&#xA; b) no cloud of operational significance;&#xA; c) no weather of significance to aviation as given in 4.4.2.3 and 4.4.2.6;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&lt;p&gt;information on visibility, runway visual range, present weather and cloud amount, cloud type and height of cloud base shall be replaced in all meteorological reports by the term “&lt;strong&gt;CAVOK&lt;/strong&gt;”.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="7214" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-04T11:44:18.307" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25809" PostTypeId="2" ParentId="25794" CreationDate="2016-03-04T09:33:01.757" Score="2" Body="&lt;p&gt;If the aircraft is subject to the ADS-B mandate of Europe, it will not be allowed to operate in European airspace after June 7, 2020 if it does not have a certified EUROCAE ED-102A (equivalent to RTCA DO-260B) compliant ADS-B transmitter. Aircraft with a maximum take-off weight exceeding 5700 kg or maximum operating true airspeed exceeding 250 knots are subject to the mandate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The USA rule is a bit different, as it allows ADS-B on universal access transceivers (UAT) below 18 000 ft which is different from the 1090ES technology used in DO-260. You can do without ADS-B in the USA after January 1, 2020, if you never fly higher than 10 000ft MSL (exceeding 10 000ft MSL is allowed as long as you don't exceed 2 500ft AGL), you do not enter or overfly class C airspace and keep further than 30 NM from class B airspace. &#xA;If your aircraft is 1090ES ADS-B equipped it must be DO-260B compliant; if it UAT ADS-B equipped it must be DO-282B compliant. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between DO-260A and DO-260B are many small changes. This list is not exhaustive:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;change in the way position integrity is encoded, &lt;/li&gt;&#xA;&lt;li&gt;addition of barometric pressure setting,&lt;/li&gt;&#xA;&lt;li&gt;new encoding aircraft length / width&lt;/li&gt;&#xA;&lt;li&gt;change in encoding of speed on surface &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Typically the update from DO-260A to DO-260B requires a firmware update and some configuration changes. However, note that the mandates include more requirements than just the ADS-B protocol version. There are requirements on the integrity of your position source (GPS) as well, and the maximum latency in the position transmission chain. In the worst case you are up for a rewiring of the GPS or even installing a new GPS. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2016-03-04T09:33:01.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25810" PostTypeId="2" ParentId="25806" CreationDate="2016-03-04T10:31:07.143" Score="2" Body="&lt;p&gt;&lt;strong&gt;Actual Definition From Annex 3&lt;/strong&gt;&#xA;When the following conditions occur simultaneously at the time of observation:&#xA;a) visibility, 10 km or more, and the lowest visibility is not reported;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note 1.— In local routine and special reports, visibility refers to the value(s) to be reported in accordance with&#xA;4.2.4.2 and 4.2.4.3; in METAR and SPECI, visibility refers to the value(s) to be reported in accordance with 4.2.4.4.&#xA;Note 2.— The lowest visibility is reported in accordance with 4.2.4.4 a).&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) no cloud of operational significance;&#xA;c) no weather of significance to aviation as given in 4.4.2.3, 4.4.2.5 and 4.4.2.6; information on visibility, runway visual range, present weather and cloud amount, cloud type and height of cloud base shall&#xA;be replaced in all meteorological reports by the term “CAVOK”.&lt;/p&gt;&#xA;" OwnerUserId="8633" LastActivityDate="2016-03-04T10:31:07.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25811" PostTypeId="2" ParentId="25801" CreationDate="2016-03-04T10:32:58.670" Score="11" Body="&lt;p&gt;&lt;strong&gt;Short Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Getting_to_Grips_With_Aircraft_Performance.html&quot; rel=&quot;noreferrer&quot;&gt;Getting to grips with Aircraft Performance&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Calibrated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;Calibrated Airspeed&lt;/a&gt; are two good places to start!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From TAS to IAS $IAS=f(TAS)$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$IAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} + K_i $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From IAS to TAS $TAS=f(IAS)$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;WARNING: the units should be taken as SI, ($\frac{m}{s},\frac{kg}{m^3},Pa$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In particular:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$a_0$: speed of soundat sea level in ISA condition = $290. 07 \; \frac{m}{s}$&lt;/li&gt;&#xA;&lt;li&gt;$P_0$: static pressure at sea level in ISA condition = $1013.25 \; Pa$&lt;/li&gt;&#xA;&lt;li&gt;$\rho$: density of the air in which you are flying $\frac{kg}{m^3}$&lt;/li&gt;&#xA;&lt;li&gt;$IAS$: indicated Air Speed $\frac{m}{s}$&lt;/li&gt;&#xA;&lt;li&gt;$K_i$: is a correction factor typical of your aircraft. You should find it in the POH.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How to get to this formula, see the long answer below.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Long Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the definition of dynamic pressure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ q_c  = \frac{1}{2} \rho v^2 $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $v = TAS$, I am assuming you are interesting in subsonic speeds (cross-country flight), so we don't consider compressibility effects for the CAS:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$CAS = a_0 \sqrt{5\left[\left(\frac{q_c}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Substituting the dynamic pressure definition in the $CAS$ as a function of $TAS$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$CAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $a_0$ is $295.070 \; \frac{m}{s}$ and  $P_0$ is $101325 \; Pa$. the density $\rho $ is the density at your altitude that day, you can get it from International Standard Atmosphere &lt;a href=&quot;http://www.digitaldutch.com/atmoscalc/&quot; rel=&quot;noreferrer&quot;&gt;calculator&lt;/a&gt; or &lt;a href=&quot;http://home.anadolu.edu.tr/~mcavcar/common/ISAweb.pdf&quot; rel=&quot;noreferrer&quot;&gt;table/formulas&lt;/a&gt;.&#xA;If you measure it from your aircraft instruments $\rho = \frac{P}{RT}$, with $R=287.058 J kg ^{-1} K^{-1}$. You should give in Pressure in Pascal (not $hPa$) and most important temperature in Kelvin $K$.&#xA;Reverting the formula above (double proof is appreciated):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{CAS}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Being &#xA;$$&#xA;IAS = CAS  + K_i \\&#xA;CAS = IAS - K_i&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where $K_i$ is a correction factor typical of your aircraft. You should find it in the POH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally we get TAS as a function of IAS $TAS=f(IAS)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So:&#xA;$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="1467" LastEditDate="2016-03-04T14:58:36.230" LastActivityDate="2016-03-04T14:58:36.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25812" PostTypeId="2" ParentId="25795" CreationDate="2016-03-04T11:20:28.403" Score="4" Body="&lt;p&gt;The aircraft was previously operated by Singapore Airlines but has been returned to Pembroke Leasing. It is probably in storage because it is not economical to sell or lease at the present time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some possible reasons why it may be uneconomical to sell or lease:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) excessive supply of aircraft for market conditions  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) cabin or seating configuration &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3) excessive hours on the aircraft, engines or components&lt;/p&gt;&#xA;&#xA;&lt;p&gt;4) age of the aircraft (14 years)&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-04T11:26:14.227" LastActivityDate="2016-03-04T11:26:14.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25813" PostTypeId="2" ParentId="25782" CreationDate="2016-03-04T12:08:23.403" Score="0" Body="&lt;p&gt;There is a way to determine North with your wristwatch, if the sun is visible through the windows (see &lt;a href=&quot;http://www.wikihow.com/Use-an-Analog-Watch-as-a-Compass&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;). This would help to notice if the plane is heading in a completely wrong direction. Many hikers know this trick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, it is even more obvious if the sun is ascending in the morning on the  completely wrong side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is in the night, many people know where the North star is, and some more skilled in astronomy may guess its location even if they see some other piece of the stellar sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this is not likely for a single random chosen individual, but if there are say 500 passengers on a plane, it may a hiker between them, and it may be an astronomer between them because even finding a certified pilot between passengers is not completely unheard of.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-03-04T12:48:22.413" LastActivityDate="2016-03-04T12:48:22.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25814" PostTypeId="2" ParentId="25705" CreationDate="2016-03-04T13:20:15.227" Score="1" Body="&lt;p&gt;It is a long structured question, I will try to keep up with the answer. As first I would like to cite some sources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I compared both CS23 and CS25 looking for the certification requirements on the lights. They are almost identical. If you want to check them yourself the keyword you want to use is &quot;Lights&quot;. The paragraphs of main interest are from 1285, to 1401, three pages in total. That said.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I was told it is a shield to avoid to blind the pilot during night flights when the strobes are on.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The light on the wingtip in this case are both position lights and anti-collision lights, the strobing light you refer to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Position lights: are described in paragraph from 1285 to 1391. There are requirements on the shielding of them and the intensity of the lights from different radians as well as the colors of them, but none from an aerodynamic point of view. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a design point of view the shield should define some dihedral angles:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Dihedral angle L (left) is formed by two&#xA;  intersecting vertical planes, the first parallel to the&#xA;  longitudinal axis of the aeroplane, and the other at110º to the left of the first, as viewed when looking&#xA;  forward along the longitudinal axis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Dihedral angle R (right) is formed by two&#xA;  intersecting vertical planes, the first parallel to the&#xA;  longitudinal axis of the aeroplane, and the other at&#xA;  110º to the right of the first, as viewed when looking&#xA;  forward along the longitudinal axis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;(d) Dihedral angle A (aft) is formed by two&#xA;  intersecting vertical planes making angles of 70º to&#xA;  the right and to the left, respectively, to a vertical&#xA;  plane passing through the longitudinal axis, as&#xA;  viewed when looking aft along the longitudinal axis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the anti collision lights: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The aeroplane must have an anticollision&#xA;  light system that&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;(1) Consists of one or more approved&#xA;  anti-collision lights located so that their light will&#xA;  not impair the crew’s vision or detract from the&#xA;  conspicuity of the position lights&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Field of coverage. The system must consist&#xA;  of enough light to illuminate the vital areas around&#xA;  the aeroplane considering the physical configuration&#xA;  and flight characteristics of the aeroplane. The field&#xA;  of coverage must extend in each direction within at&#xA;  least 75º above and 75º below the horizontal plane of&#xA;  the aeroplane, except that a solid angle or angles of&#xA;  obstructed visibility totalling not more than 0·03&#xA;  steradians is allowable within a solid angle equal to&#xA;  0·15 steradians centred about the longitudinal axis in&#xA;  the rearward direction.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;On the aerodynamics effect of vortex generator at the wingtip, I found a paper: &lt;a href=&quot;http://www.sciencedirect.com/science/article/pii/S1270963805000568&quot; rel=&quot;nofollow noreferrer&quot;&gt;Modification of a wing tip vortex by vortex generators&lt;/a&gt;. It is an experimental study without a wingtip device though. Citing from the conclusion paragraph:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The results show that substantial redistribution of wake circulation can&#xA;  be achieved by the merger of the tip vortex with a co-rotating&#xA;  vortex from the VG with the core radius of the merged vortex increased by a factor of up to five relative to the undisturbed&#xA;  tip vortex.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The VG was though positioned at a $\eta =\frac{y}{b} = 0.2$ inboard of the wingboard. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summing up the comments above, and merging &lt;a href=&quot;https://aviation.stackexchange.com/questions/8556/is-a-winglet-better-than-an-equal-span-extension&quot;&gt;this&lt;/a&gt; interesting explanation from @Peter Kämpf on winglets, what I think (yes, it is an &quot;&lt;em&gt;opinion&lt;/em&gt;&quot;, but otherwise I would need to run some 3D CFD and/or a wind-tunnel test) is that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;There would be a vortex generated in certain conditions for sure. &lt;/li&gt;&#xA;&lt;li&gt;To design this device in order to avoid winglet stall separation would be quite a challenging task. The device its positioned very outboard which would make it be more or less aligned with the winglet. I think that the close span-wise coupling between he device and the winglet would make it hard for the vortex to develop in such a way to re-attach the flow on the winglet.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-03-04T14:29:37.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25815" PostTypeId="1" CreationDate="2016-03-04T13:23:01.980" Score="3" ViewCount="1468" Body="&lt;p&gt;I was studying the Aeronautical Chart User's Guide and I came across the term 'radar minima' several times under the graphics depicting charted airports.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Blue – Airports with an Instrument Approach Procedure and/or&#xA;  RADAR MINIMA published in the high altitude DoD Flight&#xA;  Information Publications (FLIPs)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Green – Airports which have an approved Instrument Approach&#xA;  Procedure and/or RADAR MINIMA published in either the&#xA;  U.S. Terminal Procedures Publications (TPPs) or the DoD FLIPs&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Brown – Airports without a published Instrument Approach&#xA;  Procedure or RADAR MINIMA&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-03-04T13:52:13.450" LastActivityDate="2016-03-04T16:19:17.810" Title="What is radar minima?" Tags="&lt;terminology&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25816" PostTypeId="1" AcceptedAnswerId="25817" CreationDate="2016-03-04T14:05:03.827" Score="4" ViewCount="2098" Body="&lt;p&gt;I read the information below in the aeronautical chart user's guide. I have several questions. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;On the third line - Why is there an ICAO identifier for a U.S. &amp;amp; Alaska low altitude chart? I thought ICAO was for international flying? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the fourth line it says '0' and '*' but there is no explanation. What do these two symbols mean? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the fifth line it says there is a part time frequency, I assume because the tower is part time based on line three. So if this is the case, why does it need to say part time twice?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/45z4c.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/45z4c.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;CITY&lt;/strong&gt; - City&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Airport Name&lt;/strong&gt; - Airport Name&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(APT) (ICAO) [D]*&lt;/strong&gt; - Airport Identifier, ICAO Location Identifier, Class D airspace with far 93 special requirements operating part time &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;280 0* 43s&lt;/strong&gt; - Airport elevation, unknown symbol, runway length (soft field)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;(A) *109.8&lt;/strong&gt; - ATIS, Part Time Frequency&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-03-04T15:02:11.407" LastActivityDate="2016-03-04T16:11:08.300" Title="On an IFR Low Altitude Chart what does this symbol mean?" Tags="&lt;usa&gt;&lt;aeronautical-charts&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25817" PostTypeId="2" ParentId="25816" CreationDate="2016-03-04T14:20:02.860" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ROO5w.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ROO5w.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;① - ICAO ID&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As indicated, will be used for OCONUS airports only (overseas), e.g. Guam has a 4-letter ICAO designator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pB2KK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pB2KK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;② - Symbol with circle: Lighting&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An &quot;L&quot; following the elevation under the airport name means that&#xA;  runway lights are on during hours of darkness. A circle around the &quot;L&quot;&#xA;  indicates there is Pilot Controlled Lighting. A star beside the &quot;L&quot;&#xA;  means the lighting is less than continuous.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.uscg.mil/auxiliary/missions/auxair/ifr_intro.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is part of the legend, but there is no lead line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;③ - ATIS available part-time&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not the tower frequency (as your question seems to assume), but the ATIS frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This information is not redundant, the ATIS may be available full time for an airfield open part-time. This is the case for &lt;em&gt;Grand Junction Regional&lt;/em&gt; in the snapshot above.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-04T16:11:08.300" LastActivityDate="2016-03-04T16:11:08.300" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25818" PostTypeId="2" ParentId="25816" CreationDate="2016-03-04T14:26:35.967" Score="2" Body="&lt;p&gt;ICAO identifier is given for airports outside contiguous US. From &lt;a href=&quot;http://pilotworkshop.com/tips/images/faa-h-8083-National-Airspace-System.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA National Airspace System&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Airport Information&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Airport information is provided in the legend, and the symbols used for the airport name, elevation, and runway length are similar to the sectional chart presentation. ... FAA identifiers are shown for all airports. ICAO identifiers are also shown for airports outside of the contiguous United States.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The symbol in the fourth line is not a zero, but rather the letter 'L' with a circle over it. It represents the avialbility of pilot controlled lighting, and should be clear from the following image from &lt;a href=&quot;http://www.uscg.mil/auxiliary/missions/auxair/ifr_intro.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this document&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/A7M3q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/A7M3q.jpg&quot; alt=&quot;Image detail&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The explanation for '*' is given just for completeness there is an unidentified one in the fourth line.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-04T14:26:35.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25819" PostTypeId="1" CreationDate="2016-03-04T14:51:37.770" Score="3" ViewCount="702" Body="&lt;p&gt;Below are three NAVAID chart symbols. There is almost no explanation on the aeronautical chart user's guide. It even says that a navaid with an FSS will be shaded but the third box has an FSS and it isn't shaded! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to understand what everything on each of these boxes stands for. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qc7fS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qc7fS.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0HGGy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0HGGy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/B3L1a.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B3L1a.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d6ppG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d6ppG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-03-04T15:01:26.387" LastActivityDate="2016-03-04T15:48:51.040" Title="What are the differences between these IFR Low Altitude Chart Navaid Symbols?" Tags="&lt;usa&gt;&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25820" PostTypeId="1" AcceptedAnswerId="25826" CreationDate="2016-03-04T15:18:04.277" Score="14" ViewCount="3708" Body="&lt;p&gt;How do they manage to open a new route? For example Dubai-Panama. Do they have to open new airways?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2017-10-13T16:09:37.717" Title="How does an airline open a new route?" Tags="&lt;airline-operations&gt;&lt;navigation&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25821" PostTypeId="2" ParentId="25819" CreationDate="2016-03-04T15:33:23.870" Score="1" Body="&lt;p&gt;Your top example would have an FSS with the same name as the Navaid, while your bottom example would have an FSS (with a different name) that controls that Navaid -- i.e. can use it to receive &amp;amp; transmit, even though it isn't co-located.  The presence of either the shadow OR the FSS name (different from the Navaid's name) in brackets underneath will tell you that there is the ability to contact an FSS at that Navaid; without the shadow &amp;amp; with the FSS name underneath, the FSS is physically located elsewhere.  &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;This link&lt;/a&gt; (select the &quot;IFR Symbols&quot; tab) has the following graphic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VySgm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VySgm.jpg&quot; alt=&quot;FAA IFR Chart Legend&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this example (halfway down), the Jonesboro FSS controls the Pine Bluff VOR and can use 122.6 to talk to aircraft close to Pine Bluff.  In the example directly above that one, there is a remote transmitter (with no associated Navaid) that Jonesboro FSS can use to talk to aircraft on 122.55.  Either way, you're talking to Jonesboro FSS (as there is no &quot;Pine Bluff FSS&quot;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the top example in that graphic, you'd be able to talk to Wichita FSS on 122.65 using an antenna approximately at the ICT VOR -- FSS name matches the Navaid name.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-04T15:33:23.870" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25822" PostTypeId="2" ParentId="25816" CreationDate="2016-03-04T15:44:00.790" Score="0" Body="&lt;p&gt;In the continental US, an airport with an ICAO identifier is generally the same as the 3-letter FAA identifier, with the letter &quot;K&quot; in front.  (Note, not all airports with an FAA identifier have an ICAO identifier, and the FAA 3-letter identifier won't always match the IATA 3-letter identifier... almost always but not quite. Branson MO and Sawyer MI have IATA/FAA mismatches.) Elsewhere, such as Alaska, the FAA identifier for the airport may or may not match so closely. Anchorage International is ANC (FAA) and PANC (ICAO), but Elmendorf AFB is EDF for the FAA, but PAED for ICAO.  So in Alaska and Hawaii, it's very helpful to list both the 3-letter FAA identifier and the 4-letter ICAO identifier as they may or may not be similar.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-04T15:44:00.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25823" PostTypeId="2" ParentId="25819" CreationDate="2016-03-04T15:48:51.040" Score="3" Body="&lt;p&gt;The shadow in the NAVAID box indicates that the NAVAID and FSS have the same name, as in your top image. If they are different, the FSS name is given in brackets below the NAVAID box, as in your bottom image. If the FSS is not available, a thin line box is used for NAVAID (without brackets at the bottom), as in the middle figure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Aeronautical Chart User's guide&lt;/a&gt; should help you understand it better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b7RuE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b7RuE.jpg&quot; alt=&quot;Chart symbols&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Aeronautical Chart User's guide&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-04T15:48:51.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25824" PostTypeId="2" ParentId="25714" CreationDate="2016-03-04T16:06:49.143" Score="7" Body="&lt;p&gt;When we learned to fly in low-lift airfoil tailwheels, with radial or early flat-4 engines, we always expected an engine failure. Patterns were close-in, power was idled turning base (pace winds), and landings were made 3-point in a full stall. And the trainers (eg Cub, Citabria) didn't have flaps, so you learned slips to landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the advent of nose wheels, better airfoils, and the marked improvement of engines, the rate of non-fuel-exhaustion engine failures declined, and we could make bigger patterns and expect that some power would carry us to the threshold. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What we lost is a sense of what it takes to make it to the runway. And indeed the airplane private PTS only needs to show a simulated engine failure:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5aXhQ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5aXhQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The commercial PTS, however, requires that the pilot demonstrate a power-off 180 landing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OHaoz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OHaoz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which more closely represents how pilots were originally taught, and how tailwheel pilots are still taught, especially those flying radials and early trainers, like the Cub.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, although slips to landing are a normal procedure, they are not the recommended procedure for either airplanes or for gliders (almost all of which have some kind of drag device).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My preference (winds permitting):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;light tailwheels: power-off 180 to a 3-point&lt;/li&gt;&#xA;&lt;li&gt;high-drag tailwheels: power-off below 300ft to a 3-point&lt;/li&gt;&#xA;&lt;li&gt;nosewheels: low-power (1500 rpm or 15&quot;)&lt;/li&gt;&#xA;&lt;li&gt;gliders: sufficient use of drag device for a 10:1 approach&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In all cases, I am high rather than low, and close in rather than further out in the pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A no-flap landing in an airplane, which is a normal procedure, requires more airspeed because the stall speed is higher, so the approach is flatter and the airspeed is higher. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No flap landing checklists in airplanes do not specify a slip, although slips are still used as necessary. In my airplane, a no-flap landing requires 10 knots higher airspeed because the flaps are so effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an airplane that has not-very-effective landing flaps, such as the DA20 (which I have never flown), the airspeed differential between take-off flaps and  landing flaps would be much smaller, and indeed this is what shows up on the checklist:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aFKb4.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aFKb4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-04T16:31:33.263" LastActivityDate="2016-03-04T16:31:33.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25825" PostTypeId="2" ParentId="25815" CreationDate="2016-03-04T16:19:17.810" Score="3" Body="&lt;p&gt;Published minimums for an &lt;a href=&quot;https://en.wikipedia.org/wiki/Surveillance_radar_approach&quot; rel=&quot;nofollow&quot;&gt;ASR or PAR&lt;/a&gt; approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An ASR is essentially a non-precision approach with an MDA, while a PAR is a precision approach (found almost exclusively at military fields) with minimums of 200 and 1/2.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-04T16:19:17.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25826" PostTypeId="2" ParentId="25820" CreationDate="2016-03-04T16:33:39.527" Score="18" Body="&lt;p&gt;No. You do not need to create new airways. You stick up to the already existent waypoints or not, if the route flies through a segment of free-route airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the engineering department of the airline studies the route, for instance: computes the MSA (Minimum Safe Altitude) for every point, engine failure and depressurization simulations are done in order to avoid possible hazards in critical points, if the aircraft is ETOPS certified they will decide which alternative airports are available for the route, fuel computations, chart generation for arrival and departure (most of the airlines use their own charts instead of those provided by the ANSP), et cetera. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each airline has its own policy and the process may vary but fundamentally the procedure done is to make a study of all the parameters that can affect to guarantee safety and efficiency. &lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="8407" LastEditDate="2016-03-04T16:40:08.607" LastActivityDate="2016-03-04T16:40:08.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25827" PostTypeId="1" CreationDate="2016-03-04T17:20:53.090" Score="3" ViewCount="1349" Body="&lt;p&gt;On &lt;a href=&quot;https://aviation.stackexchange.com/a/24967/12220&quot;&gt;this&lt;/a&gt; answer, there is a comment that asks if there is an alerting alarm of some sort when an engine falls off an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a direct alarm from the engines specifically saying &quot;You lost an engine&quot; to warn that an engine has fallen off from the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2018-11-03T15:17:52.773" Title="Are there any cockpit indications when an engine has separated from the aircraft?" Tags="&lt;jet-engine&gt;&lt;emergency&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="25828" PostTypeId="1" AcceptedAnswerId="25836" CreationDate="2016-03-04T17:21:27.757" Score="7" ViewCount="1058" Body="&lt;p&gt;There are a lot of blue polygons on this VFR chart:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/QrWU3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QrWU3.png&quot; alt=&quot;vfr&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do they mean?&#xA;&lt;a href=&quot;https://skyvector.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-05T17:05:09.673" LastActivityDate="2016-03-05T17:05:09.673" Title="What do these polygons mean on VFR charts?" Tags="&lt;aeronautical-charts&gt;&lt;special-use-airspace&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25829" PostTypeId="2" ParentId="25828" CreationDate="2016-03-04T17:30:32.837" Score="4" Body="&lt;p&gt;See Page #10 of &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot;&gt;this document&lt;/a&gt;, which indicates that the markings show &lt;strong&gt;&quot;Prohibited, Restricted and Warning Areas&quot;&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-03-04T17:30:32.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25830" PostTypeId="2" ParentId="25801" CreationDate="2016-03-04T17:38:45.003" Score="4" Body="&lt;p&gt;I just dial in the OAT, look for the TAS in the white window, and read the IAS on the black scale.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DlUUF.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DlUUF.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-03-04T17:38:45.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25831" PostTypeId="2" ParentId="25827" CreationDate="2016-03-04T17:44:39.830" Score="16" Body="&lt;p&gt;This is the indicator that shows you when one engine falls off in a multi-engine aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dt335.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dt335.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the right engine falls, off, the little ball will move left. If the left engine falls off, the little ball moves right. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you only have one engine, or both engines fall off, you need to use a different indicator that looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qUrOs.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;if both engines fall off, this white pointer will start to move towards the &quot;40&quot;, and you might hear an alarm, a voice shouting &quot;stall, stall&quot;, or feel the stick shake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;if you have one engine and it falls off, the white pointer will move, but in an indeterminate direction.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-04T18:37:06.387" LastActivityDate="2016-03-04T18:37:06.387" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="25832" PostTypeId="2" ParentId="25820" CreationDate="2016-03-04T17:48:32.120" Score="5" Body="&lt;p&gt;Maybe this is an exception which proves the rule, or maybe this is not exactly a valid answer because it doesn't relate to the design a new complete route, but sometimes new airway segments are created, e.g. this discussion between IATA and FAA for opening two new polar segments:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Summary of Discussions of the &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/ato_intl/documents/cross_polar/CPWG17/CPWG17_WP08_CPWG16_Summary_of_Discussions.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sixteenth Meeting&lt;/a&gt; of the Cross Polar Trans East Air Traffic Management Providers Working Group (CPWG/16) 3-6 December 2013 – Ottawa, Canada&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;8.1. Based on ideas and proposals from IATA member airlines, State ATM Corporation developed two new route proposals that would supplement&#xA;  the existing cross polar routes and provide additional flexibility. &#xA;  The routes presented were:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. 7957N16858W – RODOK  to join G495&lt;br&gt;&#xA;  b. 7457N16858W – LUTEM – OLMIN – TURAN – ASKIB  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;8.2. The FAA agreed to review the routes and make an effort to limit restrictions.  These routes will be added to the ATS Route Catalogue.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The routes were later &lt;a href=&quot;http://www.icao.int/APAC/Meetings/2014%20EATSCM2/WP05%20RDGE20%20FAR%20EAST%20Report.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;discussed at ICAO&lt;/a&gt;, but seems to be still waiting for their implementation. However in the same document other routes are adjusted in the Sea of Japan:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ht4YI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ht4YI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-04T18:25:09.180" LastActivityDate="2016-03-04T18:25:09.180" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25833" PostTypeId="2" ParentId="25827" CreationDate="2016-03-04T18:08:37.413" Score="7" Body="&lt;p&gt;The B-737 has a checklist for engine separation, but no specific alarm for it.  The absence of all engine indications might be a hint, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never heard of any aircraft with such an alarm, but I don't know about all of them out there.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-04T18:08:37.413" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25834" PostTypeId="1" AcceptedAnswerId="25837" CreationDate="2016-03-04T18:38:06.530" Score="15" ViewCount="7541" Body="&lt;p&gt;Imagine that a helicopter raises its nose up and then there is a loss in speed. Can it enter a stall? If so, how do you recover from the stall?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2020-01-27T23:43:14.133" Title="Can a helicopter stall?" Tags="&lt;helicopter&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25835" PostTypeId="1" CreationDate="2016-03-04T18:43:10.943" Score="8" ViewCount="13296" Body="&lt;p&gt;I was looking at the Northrop Grumman website and came across the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_EA-18G_Growler&quot; rel=&quot;nofollow noreferrer&quot;&gt;EA-18G Growler&lt;/a&gt;, which looks very similar to the F/A-18. What are the visual differences between the two?&lt;/p&gt;&#xA;" OwnerUserId="13715" LastEditorUserId="3201" LastEditDate="2017-12-22T10:45:37.827" LastActivityDate="2018-12-05T23:14:03.650" Title="What are the visual differences between the F/A-18 Hornet/Super Hornet and the EA-18G Growler?" Tags="&lt;f-18&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25836" PostTypeId="2" ParentId="25828" CreationDate="2016-03-04T20:07:15.520" Score="11" Body="&lt;p&gt;To add a little to @abelenky's answer, you'll notice that each area has a identifier in it: SBR-522, SBP-505 etc. Those identifiers are made up of the &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code#Prefixes&quot;&gt;ICAO country prefix&lt;/a&gt;, the airspace type, and a unique code. The airspace type can be Prohibited (P), Restricted (R) or Danger (D).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since SB is the ICAO code for Brazil, SBR-522 is Brazil Restricted area #522; SBP-505 is Brazil Prohibited area#505 etc. I couldn't quickly see any nearby danger areas, but &lt;a href=&quot;https://skyvector.com/?ll=-33.683668031955634,25.142761243318184&amp;amp;chart=301&amp;amp;zoom=3&quot;&gt;here's one in South Africa&lt;/a&gt;: FAD-193, near Port Elizabeth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can look up those codes in each country's &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeronautical_Information_Publication&quot;&gt;Aeronautical Information Publication (AIP)&lt;/a&gt; or local equivalent to get more information about what each area is, what altitude it goes up to, any special rules etc.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-03-04T20:45:46.263" LastActivityDate="2016-03-04T20:45:46.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25837" PostTypeId="2" ParentId="25834" CreationDate="2016-03-04T20:21:13.927" Score="18" Body="&lt;p&gt;Yes and No.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The definition of a stall is that the airfoil stops generating lift, which happens when the critical angle of attack is reached.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an airplane, this happens during normal flight by pitching up until the critical angle of the airfoil is reached.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a helicopter, aft cyclic (&quot;pitching up&quot; in an airplane) will only serve to make the helicopter climb and slow down until it reaches equilibrium in the new attitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Helicopters, however, can suffer from what is called &quot;retreating blade stall,&quot; when the blade is at full pitch on the retreating side of the rotor:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d8nc8.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d8nc8.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't happen under normal circumstances, but there are four factors which contribute to retreating blade stall: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;fast -- close to Vne&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;heavy -- at max gross weight&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;hot -- above 35C&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;high -- at high altitude&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Retreating blade stall is considered an emergency, and can be recovered from by reducing power. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-04T23:23:19.113" LastActivityDate="2016-03-04T23:23:19.113" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25838" PostTypeId="2" ParentId="25828" CreationDate="2016-03-04T20:35:20.003" Score="4" Body="&lt;p&gt;To add to the informative answers already here, this chart excerpt is from &lt;a href=&quot;https://skyvector.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SkyVector.com&lt;/a&gt; and depicts a &lt;code&gt;World VFR&lt;/code&gt; chart of &lt;a href=&quot;https://skyvector.com/?ll=-30.536111111,-50.467222222&amp;amp;chart=301&amp;amp;zoom=6&quot; rel=&quot;nofollow noreferrer&quot;&gt;this area&lt;/a&gt; in south-eastern Brazil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where available, SkyVector uses FAA sectional charts to stitch together their &lt;code&gt;World VFR&lt;/code&gt; product. Where those are unavailable, my understanding is that SkyVector uses other available data to create their own charts. See &lt;a href=&quot;https://skyvector.com/forum/skyvector-conquers-world&quot; rel=&quot;nofollow noreferrer&quot;&gt;this excerpt&lt;/a&gt; from a SkyVector product announcement (emphasis mine):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;World VFR&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This chart is a &quot;Sectional-style&quot; VFR chart for use at low levels. For&#xA;  the United States, official FAA charts have been thoughtfully stitched&#xA;  together. &lt;em&gt;For the rest of the world, topographical and aeronautical&#xA;  data have been sourced and assembled in a very high quality rendering&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Where SkyVector has used available FAA sectional charts, all chart depictions and symbology are provided by the FAA and follow the FAA charting guidelines laid out in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Chart User's Guide&lt;/a&gt; (Aero Guide) that @abelenky linked to in his answer. See &lt;a href=&quot;https://aviation.stackexchange.com/a/25562/12720&quot;&gt;this Aviation.SE answer&lt;/a&gt; for more information on that document and it's availability. Within SkyVector some of the same information can be found on individual sectional chart renderings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, this is speculation on my part, but I understand that where SkyVector has used other topographical and aeronautical data to assemble World VFR charts outside the United States, they have chosen to use the same depictions and symbology for those charts. For this reason, the Aero Guide should be useable as a guide to understanding those renderings as well.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-03-04T23:25:49.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25839" PostTypeId="1" CreationDate="2016-03-04T22:02:40.143" Score="2" ViewCount="1836" Body="&lt;p&gt;What is difference between ground speed and airspeed? Is ground speed used only for takeoff or is it used for flight too?&lt;/p&gt;&#xA;" OwnerUserId="13555" LastEditorUserId="3201" LastEditDate="2016-03-05T10:09:03.790" LastActivityDate="2016-03-05T10:09:03.790" Title="What is the difference between ground speed and airspeed?" Tags="&lt;airspeed&gt;&lt;wind&gt;&lt;groundspeed&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-03-04T22:16:25.350" ContentLicense="CC BY-SA 3.0" />
  <row Id="25840" PostTypeId="2" ParentId="25839" CreationDate="2016-03-04T22:15:53.970" Score="1" Body="&lt;p&gt;The ground speed is the speed the aircraft is making over ground below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Indicated_airspeed&quot; rel=&quot;nofollow&quot;&gt;indicated airspeed&lt;/a&gt; (IAS) is the speed shown on the airspeed indicator. This will be different than the ground speed for various reasons, such as wind and the attitude of the aircraft. For example, if the aircraft is diving then the IAS will be greater than the ground speed. In fact, if the aircraft were diving straight down, then the ground speed could be 0 while the IAS was hundreds of knots per hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The indicated airspeed is the usual measure used in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ground speed can be calculated to estimate the time of arrival of the aircraft at some destination.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-03-04T22:15:53.970" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25841" PostTypeId="1" AcceptedAnswerId="25843" CreationDate="2016-03-05T01:03:27.013" Score="0" ViewCount="581" Body="&lt;p&gt;Imagine the rotor of a helicopter is not spinning anymore, can you control the aircraft to land safely?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-03-05T01:14:56.507" Title="If the engine of a helicopter fails, is it possible to land safely?" Tags="&lt;safety&gt;&lt;helicopter&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2016-03-05T01:17:21.230" ContentLicense="CC BY-SA 3.0" />
  <row Id="25842" PostTypeId="2" ParentId="25841" CreationDate="2016-03-05T01:14:10.230" Score="2" Body="&lt;p&gt;Helicopter can land via &lt;a href=&quot;https://en.wikipedia.org/wiki/Autorotation&quot; rel=&quot;nofollow noreferrer&quot;&gt;autorotation&lt;/a&gt;.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/uTsuq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uTsuq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastActivityDate="2016-03-05T01:14:10.230" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25843" PostTypeId="2" ParentId="25841" CreationDate="2016-03-05T01:14:56.507" Score="5" Body="&lt;p&gt;You're asking two different questions, actually.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the engines fails in a helicopter, the rotor will usually rotate and the pilot can land the helicopter by autorotation. The &lt;a href=&quot;http://avstop.com/feb_2011/jean_boulet_former_record_breaker_and_test_pilot_dies_at_age_90.htm&quot; rel=&quot;noreferrer&quot;&gt;record is from an altitude of more than 12km&lt;/a&gt; by Jean Boulet when he descended via autorotation as the engine flamed out and couldn't be restarted.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the rotor seizes for some reason in a helicopter, there is no lift produced and it will fall down. For tilt rotors like V-22, if the conditions permit (if it is in aircraft mode), the aircraft &lt;em&gt;can&lt;/em&gt; be glided like normal fixed wing aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-05T01:14:56.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25844" PostTypeId="1" CreationDate="2016-03-05T01:29:10.460" Score="2" ViewCount="237" Body="&lt;p&gt;Boeing worked its Supersonic Transport (&lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_2707&quot; rel=&quot;nofollow&quot;&gt;Boeing SST 2707&lt;/a&gt;) design in the 1960s. They gave it the number &quot;2707&quot;. Why was this aircraft given that number? Did it have some significant inside-Boeing relation to the B707 or was it just some number that followed another Boeing numbering scheme?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-04-04T02:00:05.387" Title="Why was the Boeing SST numbered &quot;2707&quot;?" Tags="&lt;aircraft-naming&gt;&lt;boeing-sst&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25845" PostTypeId="2" ParentId="25844" CreationDate="2016-03-05T01:41:33.180" Score="1" Body="&lt;p&gt;The planned cruise speed was Mach 2.7 so I always assumed 2707 was a combination of Mach 2.7 and the then current Boeing 707. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-03-05T01:41:33.180" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25848" PostTypeId="1" AcceptedAnswerId="25849" CreationDate="2016-03-05T02:17:32.580" Score="15" ViewCount="1294" Body="&lt;p&gt;There is something above the engine on the tail of this MD-11:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4iw34.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4iw34.jpg&quot; alt=&quot;md11&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airliners.net/photo/Varig/McDonnell-Douglas-MD-11/2775385/&amp;amp;sid=8ad2b3a626cf3bff1ea9938a6e757469&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-01-22T05:06:39.643" LastActivityDate="2019-01-22T05:06:39.643" Title="What is this object on an MD-11?" Tags="&lt;aircraft-design&gt;&lt;feature-identification&gt;&lt;tail&gt;&lt;md-11&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25849" PostTypeId="2" ParentId="25848" CreationDate="2016-03-05T03:04:02.093" Score="18" Body="&lt;p&gt;As was said in the comments above, it is the support structure for the engine as seen in this drawing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TW4uz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TW4uz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jKPq1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jKPq1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-03-05T03:04:02.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25850" PostTypeId="1" AcceptedAnswerId="25854" CreationDate="2016-03-05T05:33:09.710" Score="7" ViewCount="1221" Body="&lt;p&gt;Why is a strake placed on the fuselage in front of the tailplane on the Hawk aircraft?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3kH90.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3kH90.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13133" LastActivityDate="2016-03-05T12:52:21.670" Title="Why is a strake placed on the fuselage in front of the tailplane on the Hawk aircraft?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25851" PostTypeId="1" AcceptedAnswerId="26248" CreationDate="2016-03-05T08:29:05.983" Score="14" ViewCount="1055" Body="&lt;p&gt;I've been considering &lt;a href=&quot;https://aviation.stackexchange.com/questions/25834/can-a-helicopter-stall&quot;&gt;this question&lt;/a&gt;.  I believe myself to be an average pilot but I'm embarrassed to say that I could not figure out the answer to the following question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I flare and use power to maintain height, for example coming into the hover.  As I slow, I must keep increasing power.  I have enough power to hover out of ground effect.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I attempt to continue maintaining the flare, attempting to come to a stop, I will sink and if I don't do anything about it, I will hit the ground. Why?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been trying to think through all of the key aerodynamic effects but keep hitting a brick wall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S.  Fixed wing pilots - if you don't have a good understanding of helicopters, please try to resist the temptation to guess.  A helicopter in this flight regime is similar to a fixed wing in that it's a powered, heavier than air flying machine. End of list.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2020-04-22T00:00:28.310" Title="What exactly happens when I try to maintain the flare when coming to a hover?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="3" CommentCount="14" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25852" PostTypeId="1" CreationDate="2016-03-05T10:49:10.783" Score="46" ViewCount="8932" Body="&lt;p&gt;I am a person with very diverse interests and a lot of life goals I want to achieve. One of them is becoming an airline pilot (just working as one for a year or two) and the other is traveling the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to combine two goals in one, that is becoming an airline pilot after I finish college and travelling the world at the same time, i.e. flying intercontinental flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, my question is basically this: &lt;strong&gt;Is it possible to learn to fly and become an airline pilot within about 3 years (let's say age 20-23), then immediately get employed as an airline pilot and fly intercontinental routes (even as a co-pilot)?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="13860" LastEditorUserId="62" LastEditDate="2016-03-05T16:55:58.680" LastActivityDate="2016-04-07T18:14:37.073" Title="Is it practical to become an airline pilot in order to travel internationally?" Tags="&lt;commercial-aviation&gt;&lt;career&gt;" AnswerCount="6" CommentCount="16" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25853" PostTypeId="2" ParentId="25850" CreationDate="2016-03-05T11:38:46.043" Score="6" Body="&lt;p&gt;You may have noted that the tailplane of the Hawk is a full-flying surface, also called an all-moving surface. When the stick is pulled aft, the leading edge will align with the strake, forming in effect a &lt;a href=&quot;https://aviation.stackexchange.com/questions/15637/stall-delay-by-using-leading-edge-root-extensions&quot;&gt;leading edge extension&lt;/a&gt;. This will produce a vortex over the lower surface of the inner tailplane and prevent early flow separation at the tailplane root at low speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The obvious next question is: Why is it not part of the tailplane itself? Adding it to the tailplane would increase drag and produce nonlinear control forces. Since it was added later in the life of the design, fixing it to the fuselage allowed to keep the tail surfaces and their actuation unchanged. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that early Hawk versions (Mk.1, Hawk 50) lacked this detail. In flight testing, it was found that the Hawk would suddenly nose-dive with full flaps and gear up. This was dubbed &quot;phantom dive&quot;. Cutting back the flaps solved that behavior, but later, heavier versions of the Hawk needed more lift, so a different fix had to be found. From &lt;a href=&quot;http://aerosociety.com/Assets/Docs/Publications/The%20Journal%20of%20Aeronautical%20History/2013-01_HawkStory-Fraser-Mitchell.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Hawk story&lt;/a&gt; by Harry Fraser-Mitchell:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It was shown with the half model of the Hawk at Hatfield that high&#xA;  local downwash at the tail, coupled with the very large nose down&#xA;  pitching moment induced by the flap, was causing the tailplane to&#xA;  stall on its lower surface, so that it could no longer provide&#xA;  adequate balancing power. It needed more lift, extended to higher&#xA;  angles of attack.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In the case of the F-4K Phantom aircraft this was achieved by&#xA;  installing a fixed leading edge slot to the tailplane, harking back to&#xA;  demonstrations of such devices by Handley Page on wings in the early&#xA;  Twenties! A fixed slot with its associated drag was not an option on&#xA;  the Hawk although a cambered tailplane was tried on the model with&#xA;  some success. Removal of the outboard vane of the flap reduced the&#xA;  flap pitching moment to such a value that the standard tailplane could&#xA;  cope, so this was the quick solution for the RAF. However, for the US&#xA;  Navy VTX project, (and for later combat versions of the Hawk) the&#xA;  maximum possible lift was required, so that at least the outer flap&#xA;  vane had to be replaced. The dive phenomenon had to be fixed.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;An example of the cross-fertilization of knowledge due to the matrix&#xA;  working of the design department now occurred. Barry Pegram, then&#xA;  Section leader of the Fluid Dynamics section of the Aerodynamics&#xA;  Department, had been working on the adoption of leading edge root&#xA;  extensions (LERX) for the “Harrier” wing, and this work had shown that&#xA;  these devices extended the lift of the wing to higher angles of attack&#xA;  by virtue of the non-linear lift developed by the vortex flow they&#xA;  created. He proposed that these should be added to the tailplane of&#xA;  the Hawk model, but this would have had a serious effect on the&#xA;  tailplane hinge moments. The author, who was working with Barry in the&#xA;  V/STOL tunnel at Hatfield, suggested that the ‘tailplane canard vane’&#xA;  (TCV), as it was called, could be fixed to the fuselage at such a&#xA;  position that it was lined up with the flow at normal conditions, but&#xA;  with its trailing edge adjacent to, with a small clearance, the&#xA;  leading edge of the tailplane at its maximum nose down position. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Experimenting showed that these vanes could be made quite small and&#xA;  they gave a complete cure to the problem in the wind tunnel, with very&#xA;  little drag in the normal flight regime. To prove the concept in&#xA;  flight, some temporary vanes were manufactured which could rapidly be&#xA;  fitted to one of the test aircraft which had flaps with the full vane.&#xA;  First, the aircraft was flown without the TCV to establish the&#xA;  conditions under which the ‘Phantom Dive’ occurred on that particular&#xA;  aircraft. On a later flight, the TCVs were fitted and the aircraft&#xA;  flown again to the identical conditions as before. Despite every&#xA;  attempt by the pilot to instigate the phenomenon, it did not occur –&#xA;  the vanes were a complete success, even though they looked&#xA;  inconspicuously small for such a large effect.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-05T12:52:21.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25854" PostTypeId="2" ParentId="25850" CreationDate="2016-03-05T11:40:15.077" Score="5" Body="&lt;p&gt;They are called Tailplane Canard Vanes (TCV) or the side mounted rear fins (smurfs). Basically, they are vortex generators to solve the problem of tailplane under surface stall at high (negative) angles.&lt;/p&gt;&#xA;&lt;p&gt;During flight testing of the Hawk, it was found that the tailplane under surface stall was causing uncontrollable nose down pitch. From &lt;a href=&quot;http://aerosociety.com/Assets/Docs/Publications/The%20Journal%20of%20Aeronautical%20History/2013-01_HawkStory-Fraser-Mitchell.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Hawk Story:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;It was found that at forward centre of gravity in that configuration, rapid fore-and-aft movement of the control column could induce an uncontrollable nose down pitch, with the nose down attitude and speed increasing quite rapidly. ... It was dubbed the “Phantom Dive”.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The designers fixed it initially by removing the the outboard vane of the flap; however, a better solution was needed and this was achieved by placing a tailplane canard vane in front of the stabilizer. The TCVs created a voretx, that ensured that the control surfaces remained effective by preventing seperation. The image below shows the improvement.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pf87x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pf87x.jpg&quot; alt=&quot;TCV&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://aerosociety.com/Assets/Docs/Publications/The%20Journal%20of%20Aeronautical%20History/2013-01_HawkStory-Fraser-Mitchell.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Hawk Story:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;The addition of TCVs solved the problem of tail plane under surface stall. From the same document:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;With tail and TCV on, there is ample tailplane authority with aft stick (- &lt;span class=&quot;math-container&quot;&gt;$\eta_{T}$&lt;/span&gt; ) at all angles of attack in the usable range.&lt;/p&gt;&#xA;&lt;p&gt;The addition of TCVs was a cheap and effective solution of the problem of tailplane under surface stall, and allowed further development of the wing to try to achieve the low stalling speeds demanded for carrier operation in the US Navy, and for combat versions of the aircraft carrying heavy store loads.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The paper has quite a lot of additional details on solving this problem, and I suggest you go through it. According to &lt;a href=&quot;http://www.raf.mod.uk/rafcms/mediafiles/E28BE76F_5056_A318_A833EB4C9A735AD8.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;RAF Aircraft &amp;amp; Weapons Guide&lt;/a&gt;, the modificaiton was incorporated on the Hawk T2.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-05T11:40:15.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25855" PostTypeId="2" ParentId="25852" CreationDate="2016-03-05T12:06:20.003" Score="28" Body="&lt;p&gt;Even once you get a job as a commercial pilot, you're not going to be starting intercontinental routes immediately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For starters (in the US at least), you're probably only going to be able to start at a regional airline, flying short regional jet flights back and forth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airline industry is &lt;em&gt;very&lt;/em&gt; much dependent on seniority, so you'll have to put in substantial time at that regional carrier before you have a chance at even getting hired by one of the big mainline airlines. Even once you do, the routes you fly on are bid based on seniority, so you're not going to get intercontinental routes for quite a while. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, don't forget that intercontinental flights are flown on different equipment than medium range mainline flights, which are different equipment from regional jets. you're going to have to get trained and certified for several different aircraft along the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, if you become a pilot you may eventually be able to fly intercontinental routes and see the world, but it will likely take decades of work before you're in that position.&lt;/p&gt;&#xA;" OwnerUserId="1024" LastActivityDate="2016-03-05T12:06:20.003" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25856" PostTypeId="2" ParentId="25852" CreationDate="2016-03-05T12:45:10.957" Score="66" Body="&lt;p&gt;No, this is not a good idea, and No, it is not possible finish your education at 23, and then get employed as an intercontinental airline pilot. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems you have a distorted idea of what an airline pilot actually does. An intercontinental airline pilot usually spends just 24 hours at the layover destination. Much of that time is spent sleeping to recover from the fatigue of the long haul flight and sleeping to prepare for the next long haul flight. Not much time for sight-seeing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first requirement for becoming an airline pilot is a love of aviation and aircraft.  Most airline pilots today have been passionate about aviation since an early age. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will never be successful unless you are passionate about aviation due to all the roadblocks and hardships you will have to overcome in order to reach your goal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To say that you only want to do it for 1-2 years is proof enough that you don't have what it takes.   &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-05T12:57:33.813" LastActivityDate="2016-03-05T12:57:33.813" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="25857" PostTypeId="1" AcceptedAnswerId="25859" CreationDate="2016-03-05T12:54:45.283" Score="7" ViewCount="2242" Body="&lt;p&gt;During the Second World War, the British De Havilland Mosquito light bomber achieved success in raids through its sheer speed. Traveling at up to 392 mph, it could outrun virtually all piston-engined interceptors, removing the need for it to carry defensive weaponry. Later in the war though, German jets like the ME-262 could travel at speeds in excess of 500 mph, seemingly making the Mosquito obsolete. How did the Mosquito compete with these jets successfully, despite the obsolescence of its only major advantage?&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="29026" LastEditDate="2018-05-10T17:39:45.113" LastActivityDate="2020-03-24T21:47:29.187" Title="How did the De Havilland Mosquito compete with contemporary jets?" Tags="&lt;military&gt;&lt;aircraft-performance&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25858" PostTypeId="2" ParentId="25820" CreationDate="2016-03-05T13:21:00.140" Score="7" Body="&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/25826/3313&quot;&gt;Airman01's answer&lt;/a&gt;, opening a route goes beyond flying from point A to point B, you also need to:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;get landing and departure slots at each of the airports. At some with lots of spare capacity, this is easy. At others, such as the largest and busiest airports, this is very difficult, and is a process that can sometimes take years. Airlines have been known to buy competitors just to get their slots.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;arrange ground handling (jetways or stairs, loading/unloading luggage, refuelling, possibly catering and light maintenance, check-in and gate personnel). Sometimes this may be provided by the airport itself, sometimes it will be outsourced to specialised companies doing so in many places, sometimes to local companies, and other times it will be handled by the airline itself.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;have all the relevant licenses/authorizations from countries overflown as well as source and destination, and arrange for the payment of relevant taxes and fees to the appropriate authorities.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;and then you need to insert this into the rotation of the planes and crews in order to minimise downtime while still trying to find the most convenient times for your customers.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;h3&gt;EDIT&lt;/h3&gt;&#xA;&lt;p&gt;I forgot to mention that in the case of international flights, there's the issue of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Freedoms_of_the_air&quot; rel=&quot;nofollow noreferrer&quot;&gt;Freedoms of the Air&lt;/a&gt;. Overflying, stopping, flying to, from or between countries other than your own is not automatic, and is usually subject to state-level agreements.&lt;/p&gt;&#xA;&lt;p&gt;Overflying another country (First Freedom) is nearly universal (though the two states must either both be signatories of the IASTA, or have a bilateral agreement). The Wikipedia page on the topic also lists examples of flyover fees.&lt;/p&gt;&#xA;&lt;p&gt;Further freedoms are a much more complex issue, though relatively recent changes like the &lt;a href=&quot;https://en.wikipedia.org/wiki/EU%E2%80%93US_Open_Skies_Agreement&quot; rel=&quot;nofollow noreferrer&quot;&gt;EU–US Open Skies Agreement&lt;/a&gt; changed things a lot on many of the most competitive (and restricted) routes.&lt;/p&gt;&#xA;" OwnerUserId="3313" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-22T10:39:41.380" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25859" PostTypeId="2" ParentId="25857" CreationDate="2016-03-05T13:21:11.067" Score="8" Body="&lt;p&gt;The Mosquito was a great aircraft but it was not faster than Germany's Messerschmitt ME-109 and Focke-Wulf Fw 190 piston powered fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It also did not successfully compete with the jet powered Messerschmitt Me 262. The limited numbers of ME-262 were probably the only reason the Mosquito could survive in the same airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On 26 July 1944 the first aircraft to be shot down by a ME-262 was in fact a Mosquito: &lt;a href=&quot;https://en.wikipedia.org/wiki/De_Havilland_Mosquito_operational_history#Performance&quot;&gt;Mosquito Operational History&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&quot;a 262 A-1a, caught and severely damaged the Mosquito in a pursuit. The Mosquito, which managed to escape into cloud, later crashed at its destination airfield in Italy, and the airframe was written off&quot;&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-05T13:45:32.043" LastActivityDate="2016-03-05T13:45:32.043" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25860" PostTypeId="2" ParentId="25852" CreationDate="2016-03-05T13:45:03.943" Score="20" Body="&lt;p&gt;&quot;...a year or two&quot;? Seriously don't even think about it. But ignoring your lack of commitment, here are some ideas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of traveling the world, try living and working in a foreign country. This can be an incredible adventure and broaden your horizons. You'll have an understanding and appreciation for international concerns that can't be matched by merely being a tourist. You might still want to travel so you can use that place as a base to visit various destinations on your time off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Southeast Asia has experienced tremendous growth in the last few years. Some of the biggest airplane orders are coming from there. Indonesia and Malaysia are looking for good pilots. Don't know if they provide training or not. Check out AirAsia and other regional airlines. Regional in this case means the Southeast Asia region and may be international.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or the middle-east. Here's &lt;a href=&quot;https://careers.etihad.com/Etihad/job/Abu-Dhabi-Cadet-Pilot-Programme-UAE-National-BachelorHigher-Diploma-holders/56566701/&quot;&gt;Etihad training program&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.askcaptainlim.com/becoming-a-pilot-pilot-68/1068-etihad-airways-cadet-pilot-program.html&quot;&gt;This&lt;/a&gt; suggests Etihad accepts non-residents for training. &lt;/p&gt;&#xA;" OwnerUserId="11868" LastEditorUserId="11868" LastEditDate="2016-03-05T14:21:02.057" LastActivityDate="2016-03-05T14:21:02.057" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25861" PostTypeId="1" AcceptedAnswerId="25865" CreationDate="2016-03-05T14:50:07.080" Score="35" ViewCount="16368" Body="&lt;p&gt;The airspeed indicator has a red marking that means: &quot;never exceed this speed&quot; ($V_{NE}$, around 160 KIAS). Why can't you exceed that speed?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-07T15:50:40.680" LastActivityDate="2018-07-30T19:17:42.213" Title="What happens if you exceed the maximum speed on a C172?" Tags="&lt;aircraft-performance&gt;&lt;airspeed&gt;&lt;cessna-172&gt;" AnswerCount="8" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25862" PostTypeId="2" ParentId="25851" CreationDate="2016-03-05T14:54:43.737" Score="7" Body="&lt;p&gt;As I have military pilots in my family I thought I'd ask one who has flown many helicopters in combat and S&amp;amp;R situations. Here is what he told me: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In normal forward flight, the disc is slanted forward, so some/majority of the thrust is downwards, but some is backwards to counteract drag or accelerate. When you decide to slow, the disc is tilted backwards so now some of the thrust is forwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What also happens is that the relative airflow that was impinging on the top of the disc in forward flight is now impinging on the bottom of the disc as you decelerate. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In forward flight this flow is a thrust penalty because it means that the change in downward flow through the disc by the rotor blades is more limited. I.e., the air is already flowing down and the rotor blades find it harder and harder to shove it any faster. They would need to rotate faster and faster to get any lift and then hit supersonic compressibility problems. (This is why modern blades tend to be funny shaped like Lynx/Merlin etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same problem propellers have on fixed wing. There is a speed at which they just can't propel the aircraft any faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely, when the disc is tilted back to flare, the airflow is all bonus. It is known the rotary aviation as the green arrow and what allows autorotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have zoom climbed hundreds of feet upwards whilst assaulting targets in full autorotation with the collective lever full down and essentially nor requiring engines at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The upshot of this is that as you transition from normal forward flight by tilting the disc back you need to lower the collective to maintain level flight or you will zoom climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you don't get something for nothing. You are trading the forward energy of the whole helicopter for rotational energy in the head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually you slow to a stop, and at this point you require engines to sustain the rotation of your rotor system, and if you have maintained a lot of nose up it is a very significant amount of power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power required curve for helicopters is a U shape with most power being required at hover and max speed and min at about 70kt in most helicopters.&#xA;The upshot of this is as your speed tapers off you need to steadily lower the nose or can get bitten hard by the power requirement when the forward momentum ceases especially if you are flying an underpowered toy which almost all hobby helicopters are. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This thrust deficit is exacerbated if the nose is held high because not all the thrust is supporting lift, some is accelerating you backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/qMDIN_R0e68?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is an example. The pilot is coming in too hot and holds the nose very high until a very late stage. He then let's a rate of descent build and doesn't have time to arrest before hitting the ground. Hovering out of ground effect, even military aircraft don't have a lot of spare power, so it is important to correctly judge yeeha flying maneuvers and throw them away before the hover if screwing up. These guys should have thrown it away at about the moment the video starts. I have a feeling that they are approaching downwind as well which makes it all twice as bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/jGMCiDXeCF8?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is it done properly.&#xA;He simultaneously pitches the nose up and enters auto.&#xA;You can see the relative aspect of the disc to the airflow switch from slightly downwards to very much up through the disc.&#xA;As the speed bleeds off he is progressively raising the lever to maintain height as he runs out of forward energy, then as he approaches the hover he pitches back nose down.&lt;/p&gt;&#xA;" OwnerUserId="59" LastEditorUserId="11671" LastEditDate="2020-04-22T00:00:28.310" LastActivityDate="2020-04-22T00:00:28.310" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="25863" PostTypeId="2" ParentId="25861" CreationDate="2016-03-05T15:12:01.923" Score="5" Body="&lt;p&gt;Because above that airspeed, the airframe is increasingly likely to fail.&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Failure would likely start with control surfaces like the ailerons, elevator and flaps, then the wings and tail are likely to separate, resulting in total catastrophic failure.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-03-05T15:12:01.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25864" PostTypeId="2" ParentId="25861" CreationDate="2016-03-05T15:16:50.110" Score="19" Body="&lt;p&gt;You &lt;em&gt;can&lt;/em&gt; exceed the never exceed speed $V_{NE}$, but doing so will most likely result in damage to the structure. From &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2010.pdf&quot;&gt;FAA handbook of pilot knowledge&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;$V_{NE}$ —the speed which should &lt;em&gt;never&lt;/em&gt; be exceeded. If flight is attempted above this speed, structural damage or structural failure may result.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-05T15:16:50.110" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25865" PostTypeId="2" ParentId="25861" CreationDate="2016-03-05T16:50:37.743" Score="40" Body="&lt;p&gt;You can, but you have to live with the consequences. There are several things that can happen:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Depending on the vertical gusts ahead, you might not even get close to v$_{NE}$. There is another speed limit for gusty weather called &lt;a href=&quot;http://aviationglossary.com/v-speeds/&quot; rel=&quot;noreferrer&quot;&gt;v$_B$&lt;/a&gt;, and exceeding this will run the risk of overstressing the wing structure. Going above v$_B$ will &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=76002d4ec8223589d1daab8b70759df6&amp;amp;mc=true&amp;amp;node=se14.1.23_1341&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;overstress the wings in a gust&lt;/a&gt; of more than 50 ft/s, and more than 25 ft/s when flying above v$_D$. The exact values can be found in the &lt;a href=&quot;http://faculty.dwc.edu/sadraey/V-n%20diagram.pdf&quot; rel=&quot;noreferrer&quot;&gt;flight envelope diagram&lt;/a&gt; of the flight manual.&lt;/li&gt;&#xA;&lt;li&gt;On a calm day, you can fly v$_{NE}$ and even a little faster, but once you fly fast enough, flutter will become very likely. Note that &lt;a href=&quot;https://www.metabunk.org/debunked-the-role-of-aeroelastic-flutter-in-the-events-of-9-11.t3359/&quot; rel=&quot;noreferrer&quot;&gt;flutter needs some initial excitation&lt;/a&gt;, so you might fly well into the flutter speed range before flutter occurs. When it does, control surfaces will be ripped from their fittings which will make the aircraft pitch up. At that point the wings will break off.&lt;/li&gt;&#xA;&lt;li&gt;The engine on a C 172 is not powerful enough to sustain level flight at v$_{NE}$. You need to dive the aircraft, which requires some altitude. Maintaining the speed will mean that you dive into the ground, so you need to pull out of the dive in time.&lt;/li&gt;&#xA;&lt;li&gt;On really fast aircraft the pitch trim will get more nose-heavy when the aircraft approaches the speed of sound. You don't run that risk in a C 172, but faster aircraft found themselves &lt;a href=&quot;https://aviation.stackexchange.com/questions/1413/how-does-exceeding-the-critical-mach-number-of-an-aircraft-affect-its-operation/1414#1414&quot;&gt;locked into a dive which they could not end&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-05T17:17:05.077" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="25866" PostTypeId="1" AcceptedAnswerId="25867" CreationDate="2016-03-05T17:52:30.753" Score="6" ViewCount="2196" Body="&lt;p&gt;Most of the time the usage of reverse thrust is not needed. I wonder if it's an authority (e.g. FAA) requirement to land safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, in bad weather conditions or when the runway is contaminated, the brakes might not work as effectively and thus R/T may be required to land safely. However, in most of other situations the aircraft can brake OK. Given that it would probably be more efficient to land without using R/T, why don't airlines routinely do so?&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="7532" LastEditDate="2016-03-05T21:23:38.967" LastActivityDate="2016-03-06T12:21:40.257" Title="Why do commercial pilots always engage reverse thrust even if it is not necessary?" Tags="&lt;landing&gt;&lt;commercial-operations&gt;&lt;thrust-reverser&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25867" PostTypeId="2" ParentId="25866" CreationDate="2016-03-05T19:05:34.590" Score="10" Body="&lt;p&gt;The correct answer is, habit patterns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If your habit, as a pilot, is to ALWAYS select reverse thrust, you'll do so reliably even when the weather is bad, you're fighting gusty crosswinds, and there is whatever else going on. On the other hand, if you sometimes do &amp;amp; sometimes don't select reverse thrust, that habit pattern isn't there to back you up when you have the proverbial &quot;dark &amp;amp; stormy night&quot; and getting into reverse thrust right away may be the difference between staying on the runway or running off the end.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if I'm landing a fairly light aircraft on a 12,000' dry runway in DEN with a little headwind, it is entirely possible to leave the thrust reversers stowed, roll out with the speed brakes deployed, tap the brakes slightly, and exit on the last high speed taxiway at a normal taxi speed.  And I'd burn less fuel and make less noise doing that.  But at my carrier, I'm not allowed to, because it's considered that the habit pattern of always deploying the T/R is so important that it's worth it to burn that extra gas even when it isn't strictly necessary, so that on the day when it's vital, the habit pattern to grab the T/R's right after touchdown is strong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think that this is an OpSpec (i.e. FAA) requirement, at least for the aircraft that I fly, but I'm quite certain that it is a requirement in our books, so my supposition is that it's a company requirement.  If that assumption is correct, then other companies might choose to do differently (and I recall one early morning arrival into Frankfort on a Lufthansa A-320 that used NO reverse thrust, but some heavy braking instead -- presumably to reduce noise at that hour of the morning).  The fact that safety is so important, though, probably drives plenty of operators to make the same choice that our carrier does: build the habit of ALWAYS using reverse thrust -- even though that means sometimes using it when it isn't necessary.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-03-05T19:43:57.387" LastActivityDate="2016-03-05T19:43:57.387" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25868" PostTypeId="1" AcceptedAnswerId="25869" CreationDate="2016-03-05T20:23:01.017" Score="5" ViewCount="429" Body="&lt;p&gt;There are some companies that use decommissioned military aircraft for commercial high-altitude flights (for, say, tourists). Examples would be the MiG-31 and the MiG-29:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/BRQVmM6fSak?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why isn't the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_U-2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed U-2&lt;/a&gt; used for such flights? Here is a two-seat version of the U-2:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vUBjP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vUBjP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;( &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_U-2#/media/File:Lockheed_U-2_TR-1B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source&lt;/a&gt; )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the U-2 still secret? Or is it expensive to build?&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="15311" LastEditDate="2017-12-24T17:07:24.420" LastActivityDate="2017-12-24T17:07:24.420" Title="Why isn't the U-2 used for commercial purposes?" Tags="&lt;reconnaissance-aircraft&gt;&lt;lockheed-u2&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25869" PostTypeId="2" ParentId="25868" CreationDate="2016-03-05T20:57:21.193" Score="15" Body="&lt;p&gt;It is expensive to operate, and there is no economic value in what it does.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from reconnaissance and espionage, the U-2 is used for high-altitude atmospheric research, but since it is operated by NASA and man-carrying, it is subject to an immense bureaucracy. When you want to fly your own scientific instrument on it, you need to go through years of certification procedures. The instruments which are rated to fly on the U-2 are ancient and much less precise than what can be built today. Therefore, most high altitude research is done by balloons, where the bureaucracy is much less suffocating.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-05T20:57:21.193" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="25870" PostTypeId="2" ParentId="24166" CreationDate="2016-03-05T21:04:28.740" Score="4" Body="&lt;p&gt;You would need a three-axis autopilot. The nature of an unusual attitude is that it needs corrections around all three axes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-05T21:04:28.740" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25871" PostTypeId="2" ParentId="25861" CreationDate="2016-03-05T21:08:10.213" Score="4" Body="&lt;p&gt;Think of $V_{NE}$ as the speed &lt;em&gt;&lt;strong&gt;at or beyond which&lt;/strong&gt;&lt;/em&gt; the structural integrity of the airframe is not guaranteed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, parts of the airframe - which is critical for controlled flight cannot be guaranteed to perform as designed.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-03-05T21:08:10.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25872" PostTypeId="2" ParentId="25868" CreationDate="2016-03-05T21:08:10.377" Score="6" Body="&lt;p&gt;Because the owners of the U-2s (the USAF and NASA) don't make them available for commercial use. Presumably, the U-2s on display in Norway and the UK and the US aren't operable and were supplied on the condition that they wouldn't be operated.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2016-03-05T21:08:10.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25873" PostTypeId="1" AcceptedAnswerId="25874" CreationDate="2016-03-05T21:36:07.560" Score="10" ViewCount="2146" Body="&lt;p&gt;I understand that this is some sort of on-board navigation monitoring and alerting...what is it used in? Do the Garmin G500s, G1000s, or the G430s use it? Where can you find it? I know nothing about this and I am trying to figure out what it is. &lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="2143" LastEditDate="2016-03-18T17:55:24.997" LastActivityDate="2016-03-18T17:55:24.997" Title="What is &quot;required navigation performance&quot; or &quot;RNP&quot;?" Tags="&lt;navigation&gt;&lt;rnp&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25874" PostTypeId="2" ParentId="25873" CreationDate="2016-03-05T21:50:34.357" Score="11" Body="&lt;p&gt;RNP (Required Navigation Performance) is a standard which avionics manufacturers may choose to design/certify their products for.  It guarantees a particular level of navigation performance that routes and procedures can be designed around, and not have to worry about &lt;strong&gt;how&lt;/strong&gt; the navigation is being conducted, but only that it will meet requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A particular product may be certified to various levels such as RNP10, RNP5, RNP2, RNP1, RNP0.3, etc. (accurate to within 10NM, 5NM, 2NM, 1NM, 0.3NM, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To see if a particular unit is certified for RNP, and to what level, you would need to look in the aircraft flight manual / supplement and see what it says (note that this is installation specific too, as it involves antennas and &quot;full system&quot; performance, not just the capability of one piece of the puzzle).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has an advisory circular caled &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/903610&quot;&gt;AC 90-101A - Approval Guidance for Required Navigation Performance (RNP) Procedures with Authorization Required (AR) Including Change 1&lt;/a&gt; if you want more technical information on it.&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-03-05T21:50:34.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25877" PostTypeId="1" AcceptedAnswerId="25879" CreationDate="2016-03-06T00:53:47.490" Score="29" ViewCount="7171" Body="&lt;p&gt;When the turbofan is spinning inside the housing, what holds the axis? All I know is that the axis holds the fan blades.&lt;/p&gt;&#xA;" OwnerUserId="12355" LastActivityDate="2020-09-02T15:19:13.583" Title="In a turbofan what holds the spinning axis?" Tags="&lt;turbofan&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25879" PostTypeId="2" ParentId="25877" CreationDate="2016-03-06T01:05:35.550" Score="33" Body="&lt;p&gt;&lt;strong&gt;Stationary frames&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The supporting structures of a turbofan are two stationary frames with their characteristic struts, located at the ends of the engine core: One is behind the &lt;a href=&quot;https://i.stack.imgur.com/74sRU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;OGV stator&lt;/a&gt; of the fan module, the other at the aft end of the turbine module:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zEJ3A.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zEJ3A.jpg&quot; alt=&quot;Forward and rear frames on a CFM56&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;CFM56 with the two frames visible (&lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Stationary frames to spinning shafts&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;In the case of an engine with two spools, the frames support the longest shaft (N1, low pressure), which in turn supports the coaxial N2 shaft (high pressure).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZwF9u.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZwF9u.png&quot; alt=&quot;Turbofan Frames and Shafts&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Shafts are centered within frames by bearings (drawn in magenta in the next picture).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Shaft to rotors&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Disks of rotors on a spool are bolted together to form a continuous structure fixed to the related shaft. The structure is used as the inner wall for the related air duct:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MsK63.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MsK63.png&quot; alt=&quot;Turbofan Frames and Bearings&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Frames, shafts, bearings. Adapted from &lt;a href=&quot;https://www.scribd.com/doc/305212389/Cfm56-7b-Familiarization-Print&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56-7B Familiarization Manual&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;A view of the N1 shaft and the two frames, before adding the bearings and their oil sumps. The fan shaft (darker / trumpet-shaped) is fixed to the N1 shaft using grooves and can be considered part of the N1 shaft:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h5hzV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h5hzV.jpg&quot; alt=&quot;LP shaft, fan frame and turbine frame of a CFM56-7B&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;LP shaft, fan frame and turbine frame of a CFM56-7B&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The bearings and the oil sumps are added to center the N1 shaft (blue tubes are used to pressurize air-oil seals of the fan sump). The clevises used to hang the engine under the pylon strut are (barely) visible on the top of the rear frame (see &lt;a href=&quot;https://aviation.stackexchange.com/q/23151/3201&quot;&gt;this question&lt;/a&gt; for details):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xgNGE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xgNGE.jpg&quot; alt=&quot;LP shaft, fan frame, turbine frame, bearings and sumps of a CFM56-7B&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;LP shaft, fan frame, turbine frame, bearings and sumps of a CFM56-7B&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Another CG view which additional elements:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The fan disk bolted on the N1 shaft (actually fan shaft).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The fan cone and spinner bolted on the fan disk.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The two extremities of the N2 shaft coaxial to the N1 shaft.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AqmnI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AqmnI.jpg&quot; alt=&quot;Shafts of the CFM56-7B&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Shafts of the CFM56-7B&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The HP/N2 shaft (shown in red above) is centered on the LP/N1 shaft by bearings. All rotors of the HP spool form a single structure bolted to the HP shaft (shown in light blue below):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/myoc1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/myoc1.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;HP rotors of CFM56-7B. Adapted from &lt;a href=&quot;https://www.scribd.com/doc/305212389/Cfm56-7b-Familiarization-Print&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56-7B Familiarization Manual&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Frames to core stators&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Similarly, outer shrouds of stators and intermediate rings of a spool are bolted together to form continuous structures.&lt;/p&gt;&#xA;&lt;p&gt;Four stationary structures are built:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The LP compressor (booster) stators assembly is fixed to the mid-box of the fan frame (on the fan side).&lt;/li&gt;&#xA;&lt;li&gt;The HP compressor stators assembly is fixed to the mid-box of the fan frame (on the other side).&lt;/li&gt;&#xA;&lt;li&gt;The combustion chamber is fixed to the HP compressor assembly.&lt;/li&gt;&#xA;&lt;li&gt;The turbine stators assembly is fixed to the combustion chamber on one end and to the rear frame on the other end.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Overall CG view with some components highlighted:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uc6Ds.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uc6Ds.png&quot; alt=&quot;CFM56-7B cutaway&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;CFM56-7B cutaway. Original CG model by &lt;a href=&quot;https://www.deviantart.com/vhfine3d&quot; rel=&quot;nofollow noreferrer&quot;&gt;vhfine3d&lt;/a&gt;, at &lt;a href=&quot;https://www.deviantart.com/vhfine3d/art/CFM56-7B-Turbofan-Engine-Half-cutaway-View-6-612726543&quot; rel=&quot;nofollow noreferrer&quot;&gt;DeviantArt&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;From frames to wing strut&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The engine is supported by a pylon, which is supported by the wing. There are only two mount points connected to the pylon, located on the fan and rear frames. Thrust is usually transferred to the wing using the forward mount point.&lt;/p&gt;&#xA;&lt;p&gt;If it is not practical to transmit the thrust from the forward mount, e.g. because space is lacking to build a strong mount, then &lt;em&gt;thrust links&lt;/em&gt; are used to transfer thrust to the aft mount which transmits it to the pylon:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0dHcy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0dHcy.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Sources: &lt;a href=&quot;https://www.airlineratings.com/did-you-know/what-are-strakes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;left&lt;/a&gt;, &lt;a href=&quot;https://www.pcs.aero/?lightbox=dataItem-ig27xhrk&quot; rel=&quot;nofollow noreferrer&quot;&gt;right&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Other components&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;There are a few other components to support.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The air inlet is fixed on the fan case.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The fan case (which role is to create a duct for the fan and contain any broken fan blade piece) is fixed on the fan frame.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The nacelle, that is the fan cowls and the thrust reversers ducts, including the reversers, is fixed directly to the pylon. The nacelle is not really part of the engine.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The exhaust nozzle and cone are fixed to the turbine frame.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;To sum up&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Engine component are kept together using two frames.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rotors are fixed to shafts, which are maintained within the frames by bearings.&lt;/li&gt;&#xA;&lt;li&gt;Stationary components (fan case, stators, combustion chamber, etc) are bolted together and fixed the directly to the frames.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-09-02T15:19:13.583" LastActivityDate="2020-09-02T15:19:13.583" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25880" PostTypeId="2" ParentId="25877" CreationDate="2016-03-06T01:11:50.677" Score="4" Body="&lt;p&gt;I'm assuming you're asking about the shaft support. In that case, the engine shaft is supported on the engine casing using bearings (the type of which may vary).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-06T01:11:50.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25881" PostTypeId="1" AcceptedAnswerId="25883" CreationDate="2016-03-06T01:23:27.480" Score="13" ViewCount="1120" Body="&lt;p&gt;Looking at some photos, I saw that a lot of planes are very dirty (on the fuselage, not inside or in the cabin), and it is said that the dirt on the fuselage affect performance. Also insects affect the aerodynamics of the plane, so, do airlines ever clean their planes?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-09-07T16:58:49.640" LastActivityDate="2016-09-07T16:58:49.640" Title="Do airlines ever clean their planes?" Tags="&lt;airline-operations&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25882" PostTypeId="2" ParentId="25852" CreationDate="2016-03-06T07:25:05.953" Score="24" Body="&lt;p&gt;If your intention is to travel the world, then don't be a pilot. &lt;strong&gt;Instead, be a flight attendant&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the possibility of being on international flights relatively early in your career, you will likely be surrounded by a majority of female coworkers who will be very glad to let you walk the aisles, lift the luggage, calm the rowdy passengers, and deal with the occasional butt-pincher.&lt;/p&gt;&#xA;" OwnerUserId="354" LastActivityDate="2016-03-06T07:25:05.953" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25883" PostTypeId="2" ParentId="25881" CreationDate="2016-03-06T07:33:42.767" Score="17" Body="&lt;p&gt;In addition to repaints, aircraft are also periodically washed and treated to maintain the paint quality and reduce the build up of dust/grime/salt and other particulates.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are automated systems installed at some airports to clean airplanes as they taxi over these areas. Think of it as a drive through car wash, but for airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The very first applications of these were actually for the US Navy because they have a requirement to wash aircraft due to their proximity to seawater. A company called tammermatic developed a system for the navy to clean airplanes directly on the field using a set of powerful jets. Images from the &lt;a href=&quot;http://www.tammermatic.com/Heavy-Duty-Wash/Applications/Specialty/Airplane&quot; rel=&quot;noreferrer&quot;&gt;tammermatic website&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sexdy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sexdy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rDIqK.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rDIqK.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then there is the &lt;a href=&quot;http://www.pmw.de/pm_online/data/RH_1858_GB.pdf&quot; rel=&quot;noreferrer&quot;&gt;Skywash system&lt;/a&gt; (PDF brochure), developed by PMW (a company that makes concrete pumps) to wash aircraft automatically. It was first used by Lufthansa in 1997 (image cc: ARNE DEDERT / AFP):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qdMKw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qdMKw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-03-06T07:33:42.767" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25884" PostTypeId="2" ParentId="25852" CreationDate="2016-03-06T07:48:49.230" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it possible to learn to fly and become an airline pilot within&#xA;  about 3 years (let's say age 20-23), then immediately get employed as&#xA;  an airline pilot and fly intercontinental routes (even as a co-pilot)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, but not in the US. You'll have to look overseas at airlines like Emirates/Qatar etc. for that.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Airline routes are offered by seniority; and pilots that have been with the airline a significant amount of years (I am talking 5+ at minimum) are given the longer routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, where I have the most exposure to the flight training side - once you get your ATP (Airline Transport Pilot) and have acquired all the relevant type certifications - your entire purpose in life is to build up your hours as PIC (Pilot In Command) / PF (Pilot Flying).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will be doing this on regional airlines, which may be contracted out to larger airlines. You may be flying an aircraft that's painted in United colors, but its actually a regional airline used on &quot;feeder&quot; routes to the larger hub airports. This is typically the case in the US (and Europe).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, you may be employed by an airline that has no international routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of these areas - if you come to the Middle East, you may be flying international routes at the start of your career; simply because that's the only option - and you may be flying the long haul jets if that's all the airline has to offer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, Emirates (the largest operator of 777 and the A380) flies international exclusively; and the majority of their routes are medium to long haul (greater than 3 hours flight time). You may have a chance to fly internationally, but on shorter routes like Dubai - Muscat, Dubai - Bahrain, Dubai - Kuwait (this is the shortest A380 flight by Emirates, and is used for crew training/familiarization).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Qatar Airways is similar - they use their short routes for crew familiarization and training on their newer aircraft. They flew their 777-200/300LR on the Doha - Kuwait - Doha circuit when they first got the aircraft (a route normally served by the A320); and the 787 on the Doha - Dubai - Doha circuit (again, normally served by the A320).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you may not have the opportunity to fly the longer routes until well into your career with the airline; and you will be starting off (training) in smaller aircraft and &lt;em&gt;a lot&lt;/em&gt; of simulator time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typical training period for commercial pilots is between 3 and 4 years (if you are directly trained by an airline, such as Emirate's &lt;a href=&quot;http://www.emiratesflighttrainingacademy.com/&quot; rel=&quot;nofollow&quot;&gt;flight training program&lt;/a&gt;) and then you are qualified as an airline pilot.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastEditorUserId="1049" LastEditDate="2016-03-10T05:07:12.607" LastActivityDate="2016-03-10T05:07:12.607" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25885" PostTypeId="2" ParentId="25866" CreationDate="2016-03-06T10:27:06.603" Score="1" Body="&lt;p&gt;How do you know it wasn't necessary?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maybe there are planes in the pattern ready to land immediately after you. Delaying clearing the runway could effect the safety and schedules of dozens of other aircraft. &lt;/li&gt;&#xA;&lt;li&gt;Maybe your brakes or tires are going to fail partway into your braking leaving you no time to use reverse thrust&lt;/li&gt;&#xA;&lt;li&gt;maybe a portion of the runway IS contaminated. The only way to avoid it is to slow as soon  can. The longer you are at high speed the more likely a problem like this will effect you&lt;/li&gt;&#xA;&lt;li&gt;Something (another plane or animal) might encroach on the runway while you are slowing down lackadaisically &lt;/li&gt;&#xA;&lt;li&gt;Wind or other weather phenomenon might effect your high speed landing roll. The period of time when a plane is near flight speeds while touching the ground is one of the most dangerous times in a flight. Many bad things can happen while &quot;fast taxiing&quot;&lt;/li&gt;&#xA;&lt;li&gt;Missing an earlier taxiway might result in a longer taxi that's even more expensive than a little thrust reversal. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The danger level is so elevated, there is just no reason good enough to maintain high speed while on the ground, other than when you intend to take off. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastEditorUserId="12116" LastEditDate="2016-03-06T10:33:12.870" LastActivityDate="2016-03-06T10:33:12.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25886" PostTypeId="2" ParentId="25877" CreationDate="2016-03-06T11:35:53.853" Score="20" Body="&lt;p&gt;Struts. Lots of them, and with an aerodynamic shape so they don't cause too much drag. Some of those struts double as stator vanes and reduce the swirl of the internal flow. By doing this they add a little thrust. Others house the driveshafts by which rotational energy is taken from the shaft to spin pumps and generators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe it helps to watch &lt;a href=&quot;https://www.youtube.com/watch?v=Q3OiVuAKN9w&quot; rel=&quot;noreferrer&quot;&gt;this YouTube video&lt;/a&gt;. I pasted a screen shot from it below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mAGCZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mAGCZ.jpg&quot; alt=&quot;Jet engine cutaway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engine cutaway. The bright orange shows where the structure has been cut. In the grey gaps you see plenty of vanes and struts: They hold the shaft bearings in place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On multi-spool engines the outer spool is held in place by the struts and has internal bearings to keep the inner spool in place. Since the outer, high-pressure spool is shorter, the inner, low-pressure spool emerges from the outer spool at both ends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://patentimages.storage.googleapis.com/US20050135926A1/US20050135926A1-20050623-D00000.png&quot; rel=&quot;noreferrer&quot;&gt;This drawing from a patent&lt;/a&gt; shows moveable stator vanes. They are arranged like spokes on a wheel. Each disk of stators is placed between two rotor disks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UVJbf.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UVJbf.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stator vanes (26 and 28) held moveably in place by bolts (32 and 44) and interspersed with rotor vanes (24). A lever (38) on each vane is moved by an actuator ring (36) and adjusts the incidence of the stator vanes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-06T11:45:46.547" LastActivityDate="2016-03-06T11:45:46.547" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25887" PostTypeId="2" ParentId="25866" CreationDate="2016-03-06T12:21:40.257" Score="-3" Body="&lt;p&gt;How can we say that it's not necessary?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd say that the reason I use reverse more then brakes is that it's my airline procedure and Airbus says that too!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use of brakes to slow down airplane after high speed landing is not good for tyre's health. So what we do normally is slow down the airplane by thrust reversers till 40-60 knots and then we use brakes. &lt;/p&gt;&#xA;" OwnerUserId="13872" LastActivityDate="2016-03-06T12:21:40.257" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25888" PostTypeId="2" ParentId="25736" CreationDate="2016-03-06T14:42:14.570" Score="2" Body="&lt;p&gt;Because it increases the number of syllables being spoken thus increasing the likelihood of correct communication.&lt;/p&gt;&#xA;" OwnerUserId="13875" LastActivityDate="2016-03-06T14:42:14.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25889" PostTypeId="1" AcceptedAnswerId="25890" CreationDate="2016-03-06T17:51:59.747" Score="5" ViewCount="963" Body="&lt;p&gt;The A380 has 4 nose-wheel doors. Look:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1BkGC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1BkGC.jpg&quot; alt=&quot;qantasa380&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Qantas/Airbus-A380-842/2788797/L/&amp;amp;sid=5d45b4f56c689507c38c7ad60fd13eb1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why does it have 4 nose-wheel doors?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="2171" LastEditDate="2016-03-07T12:53:45.840" LastActivityDate="2016-03-07T12:53:45.840" Title="Why do some aircraft have 4 nosewheel doors?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25890" PostTypeId="2" ParentId="25889" CreationDate="2016-03-06T18:56:19.690" Score="16" Body="&lt;p&gt;Having multiple door sections for the nose gear is a common design. Looking closely at the photo below may make the reason more clear:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xwPQz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xwPQz.jpg&quot; alt=&quot;A380 from below&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the nose gear retracts, it swings forward. You can see that the wheels will need a larger opening than the narrower strut. So instead of having one door with a strange shape or that is larger than it needs to be, it is split into two sections. This also allows the forward doors to be closed once the gear is extended, which reduces drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Splitting the doors down the middle allows for symmetry, and it reduces the amount of surface area each hinge or actuator must support. This results in 4 separate door sections.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at the main landing gear, you can see it uses a similar design. For example, the outboard gears swing inwards on retraction. The doors that cover the main gear bays are larger, and are only open during extension or retraction, and are otherwise closed. The smaller doors at the locations of the struts remain open.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-03-06T22:19:55.640" LastActivityDate="2016-03-06T22:19:55.640" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25891" PostTypeId="5" CreationDate="2016-03-06T20:41:07.103" Score="0" Body="&lt;p&gt;The Boeing SST (&lt;strong&gt;S&lt;/strong&gt;uper&lt;strong&gt;s&lt;/strong&gt;onic &lt;strong&gt;T&lt;/strong&gt;ransport), best known under the name &quot;Boeing 2707&quot; (although its actual &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt; model designation was the Boeing [Model] 733), was designed in the 1960s, but never built. It was one of several &lt;a href=&quot;/questions/tagged/supersonic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;supersonic&amp;#39;&quot; rel=&quot;tag&quot;&gt;supersonic&lt;/a&gt; &lt;a href=&quot;/questions/tagged/airliner&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;airliner&amp;#39;&quot; rel=&quot;tag&quot;&gt;airliner&lt;/a&gt; designs of its time; however, out of the many SST concepts of the 1960s, only the &lt;a href=&quot;/questions/tagged/concorde&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;concorde&amp;#39;&quot; rel=&quot;tag&quot;&gt;concorde&lt;/a&gt; and &lt;a href=&quot;/questions/tagged/tu-144&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tu-144&amp;#39;&quot; rel=&quot;tag&quot;&gt;tu-144&lt;/a&gt; were built, flown, and placed into service (and the latter only briefly).&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-10-09T12:42:45.290" LastActivityDate="2019-10-09T12:42:45.290" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="25892" PostTypeId="4" CreationDate="2016-03-06T20:41:07.103" Score="0" Body="Used for questions about the Boeing SST, commonly known as the 2707 (although formally the Boeing 733)." OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-10-09T12:42:48.233" LastActivityDate="2019-10-09T12:42:48.233" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="25893" PostTypeId="1" AcceptedAnswerId="25901" CreationDate="2016-03-07T00:45:18.610" Score="5" ViewCount="1848" Body="&lt;p&gt;I have been confused about the relation of yaw and pitch in propeller powered aircraft. When such an aircraft is pitching up, will it yaw to the left or right? Conversely, when it's pitching down, which way will it yaw?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I try this out on X-plane, the plane turns left when I take off. However, some online material insists that the plane will yaw to the right when I am pitching up. This is confusing me. What's the best explanation for this?&lt;/p&gt;&#xA;" OwnerUserId="13883" LastEditorUserId="5517" LastEditDate="2016-03-07T13:37:36.480" LastActivityDate="2016-03-07T14:29:50.713" Title="How does yaw relate to pitch?" Tags="&lt;pitch&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25894" PostTypeId="2" ParentId="20921" CreationDate="2016-03-07T00:45:22.157" Score="4" Body="&lt;p&gt;Specific information about requirements is difficult to find. However there is some information that is readily available concerning the Q400 and available ground power units.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Q400 can start its engine with the onboard batteries, thus the necessary power requirement would not be nearly as big as with the A320 series.&lt;/li&gt;&#xA;&lt;li&gt;Ground Power Units are usually supplied in 7,5, 15, 30, 60, 90, 120, 150 and 180kVA configurations&lt;/li&gt;&#xA;&lt;li&gt;The Q400 is listed to have two TRUs which can output maximum of 300A 28VDC from a 115VAC (~73A) source. &lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=Q400-Electrical.pdf&quot; rel=&quot;nofollow&quot;&gt;Source: Q400 Eletrical&lt;/a&gt; This would equal to a 90kVA Ground Power Unit, which according to Power Systems International provides 72A.&lt;/li&gt;&#xA;&lt;li&gt;The Q400 has one 45kVA electrical generator per turbojet.&lt;/li&gt;&#xA;&lt;li&gt;According to the Q400 Electrical document the Q400 has 24-volt NiCad batteries; Main and auxiliary, which both total to 80Ah.&lt;/li&gt;&#xA;&lt;li&gt;The same document also states that the Q400 External Power Protection Unit does not monitor amperage, thus will not monitor total power. Some other system related with engine starting will most likely still monitor total power.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.aia.org.nz/site/aianz/files/GPU%20Code//GPU%20Code%20Master%20Document.pdf&quot; rel=&quot;nofollow&quot;&gt;Aviation New Zealand&lt;/a&gt; provides the following details:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Small business jets fitted with 115 V 3 phase systems may be supplied by lower&#xA;  power units, typically 7.5 kVA and 15 kVA. Aside from over-power limits, all other&#xA;  parameters are likely to be similar to the above. &quot; above=minimum 45kVA (as according to the document is specified in &#xA;  ISO 6858:1982 (E): Aircraft Ground Support Electrical Supplies – General&#xA;  Requirements;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on these details I think that the Q400 does not have specific external power requirements. Most likely a minimum of 7.5kVA is still recommended, as that is the lowest powered GPU I could find. However you might end up charging the batteries first, as the 7kW from the GPU might not be enough to start the engines. A 30kVA generator with 150% overload rating for 60 seconds is also most definitely enough since it can provide the exact 45kVA that is provided by the generators already in the engines of the Q400.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best guestimate calculation I could come up of what the engines need to be started is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A320 CFM56 provides about 30000hp max, while the PW100 provides about&#xA;  5000HP&#xA;      The CFM56 is started by a APS3200 APU, which provides 447hp, of which about 330hp can be used by the compressor equaling to about&#xA;  240kW.&#xA;      Based on the hp difference of about 15%, we will assume the PW100 requires &#xA;      only 15% of that power to start, which would be 36kW or ~40kVa. &#xA;      Of course not all of the 240kW provided by APS3200 would be required for a     CFM56 to start, so I'm pretty confident that a Q400 engine will start with a 30kVa GPU.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think in the end it might come up to the question of using the batteries more, thus them needing more maintenance. NiCd usually rated to 1500-2000 recharge cycles, on Q400 and aircraft batteries it is most likely even lower.&lt;/p&gt;&#xA;" OwnerUserId="13773" LastEditorUserId="13773" LastEditDate="2016-03-07T01:33:46.653" LastActivityDate="2016-03-07T01:33:46.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25895" PostTypeId="2" ParentId="25893" CreationDate="2016-03-07T01:55:57.437" Score="0" Body="&lt;p&gt;From personal experience when pitching up on climb out after take off, I have to apply right rudder because the aircraft wants to yaw left. I've been told its because of engine torque at high power and slow speed.&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2016-03-07T01:55:57.437" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25896" PostTypeId="1" AcceptedAnswerId="25898" CreationDate="2016-03-07T02:00:36.493" Score="47" ViewCount="15159" Body="&lt;p&gt;There is a little door on the upper deck above the cockpit:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2GJDH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2GJDH.jpg&quot; alt=&quot;KLM 747&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/KLM---Royal/Boeing-747-406M/2721102/&amp;amp;sid=dc22971f1358b7b170e751c4f6587ccb&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;, (modified to indicate location of hatch).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that door? What is its purpose?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="3386" LastEditDate="2017-06-04T09:49:40.163" LastActivityDate="2017-06-04T09:49:40.163" Title="What is this hatch above the cockpit of a 747?" Tags="&lt;boeing-747&gt;&lt;doors&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25897" PostTypeId="2" ParentId="25835" CreationDate="2016-03-07T02:20:13.763" Score="12" Body="&lt;p&gt;You asked about visual differences. The main visual difference is that there are no guns on the EA-18G, just AIM-120 AMRAAM or AGM-88 HARM missiles. Other than that the visual differences are minimal. The airframe is still a F/A-18F Super Hornet, where -F stands for twin-seat. Engines are also the same General Electric F414-GE-400, however I suspect there could be some differences in regards to the engine auxiliary equipment, such as the electrical generator. I also suspect there is additional equipment added for the sole purpose of conditioning the electrical power and insulating everything to keep interference minimal. It is even possible that there are optical fibers in areas where on the F/A-18F copper cables are still used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Main differences:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Dedicated electronic attack equipment, e.g. what makes the aircraft an EA-18G, has been put in the place of the cannon.&lt;/li&gt;&#xA;&lt;li&gt;The EA-18G has one extra protruding antenna on the back, along with the satcom antenna behind it.&lt;/li&gt;&#xA;&lt;li&gt;The missile launch rails on the ends of the wings seem to be permanently modified to support the ALQ-218 Tactical Jamming Receiver, which is the same pod as on the EA-6B Prowler.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here is an image of the EA-Growler showing some of the external modifications and what they’re for:&#xA;&lt;a href=&quot;https://web.archive.org/web/20171109002558/https://www.airforce.gov.au/imgs/GrowlerCapacity.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://web.archive.org/web/20171109002558/https://www.airforce.gov.au/imgs/GrowlerCapacity.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://web.archive.org/web/20171109002558/https://www.airforce.gov.au/imgs/GrowlerCapacity.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;airforce.gov.au/Archive.org&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="13773" LastEditorUserId="13773" LastEditDate="2018-12-05T23:14:03.650" LastActivityDate="2018-12-05T23:14:03.650" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25898" PostTypeId="2" ParentId="25896" CreationDate="2016-03-07T02:39:04.670" Score="76" Body="&lt;p&gt;It's an emergency escape hatch. There are inertial reels in the cockpit ceiling adjacent to the hatch to allow the cockpit crew to exit the airplane. See &lt;a href=&quot;http://articles.latimes.com/1986-09-06/news/mn-12687_1_cockpit-crew&quot;&gt;this link for an account of their use escaping the aircraft during a hijacking&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There were five reels in the 747-100/200 aircraft. The cockpit had five seats: pilot, co-pilot, flight engineer, and two observer seats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also sometimes used in third world countries to send a guy out to clean the cockpit windshield. In Mumbai I once made the mistake of asking the windshield to be cleaned, thinking, of course, they'd do it with a cherry picker. Much to my surprise, bare feet appeared at the top of the windshield followed by this poor fellow who was maneuvering into place to clean the windshield. He had a rope tied around his waist, but had he fallen it would have been bad because the rope was anchored through the hatch, which meant he would have swung badly had he fallen.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-03-08T08:20:35.263" LastActivityDate="2016-03-08T08:20:35.263" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="25899" PostTypeId="2" ParentId="25861" CreationDate="2016-03-07T03:54:46.077" Score="1" Body="&lt;p&gt;The answer depends on how much you exceed V_ne.  I do not have the information for this particular aircraft in front of me, so I can not say what will happen at a specific airspeed.  Cessna spent a lot of money and time on engineering and flight testing to come up with the maximum airspeed (V_ne).  There is a safety factor built in to this calculated and tested speed.&#xA;One situation is flying level at a high altitude, then go in to a steep dive.  This may cause an overspeed condition.  One of the first problems as a result of overspeed, will start out as a vibration of control surfaces and controls. The chance for loss of control by the pilot due to mechanical failure or metal fatigue will increase exponentially, as does the airspeed.&#xA;The C172 has airfoil designs meant for low speed. Depending on the exact plane and loading this could differ slightly, but the stall speed is 49 KIAS.&lt;br&gt;&#xA;With its straight, high lift wing structure,  the airfoil may actually completely loose its lift at a very high airspeed.&#xA;As the airspeed increases, farther above the V_ne, the craft will basically start to tear apart and disintegrate.  &lt;/p&gt;&#xA;" OwnerUserId="13886" LastEditorUserId="7532" LastEditDate="2016-03-07T04:31:00.510" LastActivityDate="2016-03-07T04:31:00.510" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25901" PostTypeId="2" ParentId="25893" CreationDate="2016-03-07T10:47:37.650" Score="5" Body="&lt;p&gt;&lt;strong&gt;How does yaw relate to pitch?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are four forces at play on a single engine aircraft that can cause turning tenancies or Yaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason a single-engine propeller aircraft yaws left at T/O is due to  Asymmetrical Thrust (P-Factor). At high angles of attack the right side of the propeller disc creates more thrust than the left side and this causes Yaw to the left. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Gyroscopic Precession causes a yaw to the right when an aircraft is suddenly pitched up(tail is lowered or nose is raised) and a yaw to the left when an aircraft is suddenly pitched down. (tail is raised or nose is lowered). &#xA;This force is only apparent while the aircraft's Pitch is changing, once the pitching action is stopped, the force is gone. (not present in a steady nose up climb)&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slipstream effect causes a slight yaw to the left, and slight roll to the right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine torque causes a roll to the left.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most single engine aircraft today have a clockwise spinning propeller. All these forces would be the opposite if it were a counter-clockwise spinning propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more detailed explanation can be found here: &lt;a href=&quot;http://cfi-wiki.net/w/Turning_Tendencies&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turning Tendencies&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Me1s5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Me1s5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x7moA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x7moA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mZCQA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mZCQA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-07T14:29:50.713" LastActivityDate="2016-03-07T14:29:50.713" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25903" PostTypeId="1" AcceptedAnswerId="25905" CreationDate="2016-03-07T13:25:57.420" Score="7" ViewCount="21071" Body="&lt;p&gt;What are the lumps (Circled) on top of these two Boeing 737s? I looked it up but I only found the answer for one specific Virgin Blue 737.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZOTkt.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZOTkt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Original image &lt;a href=&quot;http://www.jetphotos.net/photo/8165291&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-07T13:46:24.897" Title="What is the lump on top of the Boeing 737?" Tags="&lt;boeing-737&gt;" AnswerCount="2" CommentCount="1" ClosedDate="2016-03-07T17:25:56.330" ContentLicense="CC BY-SA 3.0" />
  <row Id="25904" PostTypeId="2" ParentId="25903" CreationDate="2016-03-07T13:33:31.570" Score="4" Body="&lt;p&gt;It looks like satellite data link antenna &lt;a href=&quot;https://aviation.stackexchange.com/a/11762/524&quot;&gt;discussed here&lt;/a&gt;. It provides internet connection for passengers.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-07T13:33:31.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25905" PostTypeId="2" ParentId="25903" CreationDate="2016-03-07T13:35:15.877" Score="6" Body="&lt;p&gt;It is the antenna for the &lt;a href=&quot;http://gizmodo.com/every-major-airlines-wifi-service-explained-and-ranked-1701017977&quot; rel=&quot;noreferrer&quot;&gt;inflight wifi system&lt;/a&gt;. The Southwest aircraft has a Ku band antenna on the top, allowing it to access the internet through satellites. The United aircraft appears to have a similar system.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-03-07T13:46:24.897" LastActivityDate="2016-03-07T13:46:24.897" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25908" PostTypeId="1" AcceptedAnswerId="25910" CreationDate="2016-03-07T14:33:36.737" Score="4" ViewCount="1076" Body="&lt;p&gt;In this image of a U2S, what it the very unaerodynamic looking pod at the wing-tip? It looks like it holds some sort of sensor package. However, it doesn't seem to appear on all U2s (at least not based on photos on Wiki).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/b/bf/Lockheed_U-2_TR-1B.jpg&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/b/bf/Lockheed_U-2_TR-1B.jpg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/b/bf/Lockheed_U-2_TR-1B.jpg&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_U-2&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2016-03-07T23:30:08.440" Title="What is this pod at the wing-tip of a U2?" Tags="&lt;military&gt;&lt;wing&gt;&lt;sensors&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25909" PostTypeId="2" ParentId="25908" CreationDate="2016-03-07T15:23:58.443" Score="0" Body="&lt;p&gt;In &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/90464main_ER2handbook.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; you can find the handbook of the &quot;civil&quot; version on the U2, the ER-2 by NASA. Researching here and there it seems to be a &quot;pod&quot;. In particular from the document above:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Other payload areas that have been used in the past, including the&#xA;  wing tips, [...]  can  support  small  instrument  assemblies. The&#xA;  structural and electrical connections for these non-standard installa-&#xA;  tions require individual consideration. Contact Lockheed Engineer-&#xA;  ing  for  attachment  details  if  you  are  considering  one  of  these&#xA;  locations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What is inside it depends on the versions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://pubs.usgs.gov/of/1996/0276/report.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; in the 90s they were proposing the wing tip to install potassium magnetometers to make high altitude magnetometric measurements ove Alaska.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.clubhyper.com/reference/u2sdwa_1.htm&quot; rel=&quot;nofollow&quot;&gt;this site&lt;/a&gt; it is a pod used for Electronic Counter Measures (&lt;a href=&quot;http://hsfeatures.com/features04/u2sdwa_2.htm&quot; rel=&quot;nofollow&quot;&gt;ECM&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ECM has been upgraded in 2005, but from the photos on Airliners.net it seems to be there since before 2005. &lt;/p&gt;&#xA;" OwnerUserId="13754" LastActivityDate="2016-03-07T15:23:58.443" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25910" PostTypeId="2" ParentId="25908" CreationDate="2016-03-07T15:24:59.190" Score="6" Body="&lt;p&gt;The pod contains the Radar Warning Reciever (RWR). The variant in the picture is the TR-1B, which had wingtip mounted RWR units. According to &lt;a href=&quot;http://www.globalsecurity.org/intell/systems/u-2-variants.htm&quot; rel=&quot;nofollow&quot;&gt;globalsecurity.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Air Force has fielded new electronic countermeasures on the aircraft, giving it a jamming capability and upgraded radar warning equipment with wing-tip mounted digital receivers.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As an another exmaple, SAAB seems to have put &lt;a href=&quot;http://saab.com/globalassets/commercial/air/electronic-warfare/radar-warning-receivers/bow/bow-product-sheet.pdf&quot; rel=&quot;nofollow&quot;&gt;RWR on the wingtips of Gripen&lt;/a&gt;, though the equipment are certainly different (U-2 uses &lt;a href=&quot;http://www.businesswire.com/news/home/20051020005396/en/BAE-SYSTEMS-Advanced-Defensive-System-Deployed-U-2&quot; rel=&quot;nofollow&quot;&gt;AN/ALQ variants&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the bottom of the 'pod' has (wingtip) landing skid at the bottom and navigation light on the side. The RWRs face outside at an angle of ~45$^{\circ}$. This (containing RWR, skid and nav lights in a single package) is a later design and was added to the exiting U-2Rs as retrofit. It was not avialble in the earlier models. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-03-07T23:30:08.440" LastActivityDate="2016-03-07T23:30:08.440" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25911" PostTypeId="2" ParentId="23176" CreationDate="2016-03-07T15:56:51.877" Score="0" Body="&lt;p&gt;It's possible that you are hearing the blade tips 'brushing' on the honeycomb seals (it's what the blades seal into at the tip). Look up &quot;Turbine shroud seals....&quot;&lt;/p&gt;&#xA;" OwnerUserId="13901" LastActivityDate="2016-03-07T15:56:51.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25912" PostTypeId="1" AcceptedAnswerId="25913" CreationDate="2016-03-07T16:25:57.637" Score="3" ViewCount="3010" Body="&lt;p&gt;There are some cargo aircraft that have windows which are not covered. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4sQwU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4sQwU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the second deck above where it says &quot;Hong Kong Asia's World City&quot; the aircraft has 3 uncovered windows. Source: &lt;a href=&quot;http://www.airliners.net/photo/Cathay-Pacific-Airways/Boeing-747-867F-SCD/2345584/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;br&gt;&#xA;Also here:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9WN5n.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9WN5n.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Martinair-Cargo/Boeing-747-412%28BCF%29/2774380/&amp;amp;sid=0fbb5f03d1b747884d20748ce994c767&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the upper deck of the Martinair 747 the windows are not covered. My question is: if the aircraft is used for cargo, why do they leave the windows uncovered?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2016-03-07T17:25:58.457" Title="Why do some cargo aircraft have windows?" Tags="&lt;windows&gt;&lt;cargo&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-03-08T12:53:36.860" ContentLicense="CC BY-SA 3.0" />
  <row Id="25913" PostTypeId="2" ParentId="25912" CreationDate="2016-03-07T16:30:05.680" Score="7" Body="&lt;p&gt;Some cargo aircraft do have limited seating, as mentioned in the comments it could be for the relief crew, load officer, or other employees making a hop on the plane. Here is a nice &lt;a href=&quot;http://josefindsaway.com/2014/09/03/flying-in-style-the-centurion-cargo-way/&quot; rel=&quot;nofollow noreferrer&quot;&gt;blog post about  flying in a cargo plane&lt;/a&gt;. &lt;a href=&quot;http://www.nycaviation.com/2015/02/anatomy-freighter/#.Vt2tlJMrKV4&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article covers it pretty well also&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6ReET.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6ReET.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://josefindsaway.com/2014/09/03/flying-in-style-the-centurion-cargo-way/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some cargo planes are also old passenger planes and some of the windows may be left in place.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-07T17:25:58.457" LastActivityDate="2016-03-07T17:25:58.457" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25914" PostTypeId="1" AcceptedAnswerId="25929" CreationDate="2016-03-07T17:51:07.673" Score="3" ViewCount="220" Body="&lt;p&gt;Suppose I have an ADS-B IN on my aircraft and I am interested in receiving also data sent from ADS-B OUT of my own aircraft. Is it technically possible or are there any issues due to the relative position between transmitter and receiver or anything else?&lt;/p&gt;&#xA;" OwnerUserId="13903" LastEditorUserId="12220" LastEditDate="2016-03-07T18:02:47.113" LastActivityDate="2016-03-08T02:44:17.410" Title="Is an ADS-B IN able to receive signal from ADS-B OUT of the same aircraft?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25915" PostTypeId="1" AcceptedAnswerId="25917" CreationDate="2016-03-07T18:01:18.380" Score="1" ViewCount="403" Body="&lt;p&gt;Some aircraft used in long-haul flights arrive at the airport daily at 10 am and stay there until 7 pm. Why do the airlines send their planes and make them stay in the airports for more than 9 hours every day?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-07T18:17:07.307" LastActivityDate="2016-03-07T19:15:07.697" Title="Why do some aircraft stay in airports for a long time?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-03-07T19:45:34.983" ContentLicense="CC BY-SA 3.0" />
  <row Id="25916" PostTypeId="1" AcceptedAnswerId="25918" CreationDate="2016-03-07T19:05:51.883" Score="5" ViewCount="1896" Body="&lt;p&gt;&lt;strong&gt;&lt;em&gt;Question Background&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm studying the internal structure and components of a turbojet. I can see there is a shaft between the compressor and the turbine, so that energy is mechanically extracted from the exiting gas and used to help the compressor rotate. You can appreciate it in the next image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xnc35.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xnc35.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Question&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand the shaft is there so that the turbine helps the compressor move. But this introduces a serious constraint: both the compressor and the turbine &lt;em&gt;need&lt;/em&gt; to rotate at the same speed. Is this true in general? How is this managed when there are several shafts connecting several compressors/turbines? Are reduction boxes needed here or do they, in fact, move at the same speed? Is this a big deal, does it introduce any serious limitation/drawbacks regarding the exiting air power?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just started studying jets, hope the answers are not very trivial.&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="12220" LastEditDate="2016-03-07T19:51:18.020" LastActivityDate="2016-03-07T20:28:14.903" Title="What are the limitations of using a single shaft between the compressor and turbine in a jet engine?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25917" PostTypeId="2" ParentId="25915" CreationDate="2016-03-07T19:15:07.697" Score="2" Body="&lt;p&gt;There are many reasons. At least one is that the airline may not need that airframe type until later that day (the next flight that requires said airframe). Airlines don't just fly any plane they have on any route they have, this would be terribly inefficient and involve using an airplane that is not needed for a given mission. Take any major airline for example that fly large planes to lots of destination in Europe. Lets say that they have a 777 Arrive at EWR from Paris. The next long haul flight that airline has out of EWR is that evening to Dublin. But though out the day the carrier has 2 commuter flights down to Charlottesville VA totaling about 100 passengers between the two flights. They are not going to use a 777 to move 100 people and some light bags, so the plane sits until its needed again. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All planes (even non commercial) are built for a given &quot;mission&quot; much like you would not buy a Ferrari if you wanted a car that was good on gas. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-03-07T19:15:07.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25918" PostTypeId="2" ParentId="25916" CreationDate="2016-03-07T19:18:07.710" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How is this managed when there are several shafts connecting several compressors/turbines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The different shaft will rotate at different speed from each other, but the relative compressor/turbine pairs will rotate at the same speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Expanding a little, in the most complex case that I heard of, there are 3 shafts: High Pressure (HP), Intermediate-Pressure (IP) and Low Pressure (LP)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Zkxok.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zkxok.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.latestpilotjobs.com/interviews/view/subject/Cathay+Pacific+Pilot+Interview+and+Assessment.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HP turbine and HP compressor will rotate at the same speed, but this is not necessarily equal (in fact is highly likely that it will be different, otherwise there would not be the need for different shafts) to the speed of the IP compressor/turbine couple. And this will be different also from the speed of the LP turbine/fan couple.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are reduction boxes needed here or do they, in fact, move at the same speed?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They generally rotate at the same speed. And generally you don't want gear boxes in the central section of your engine. Apart from the maintenance nightmare that they would become, given the rotational speeds and energies involved, they would be extremely heavy, inefficient and would constitute a critical system quite prone to failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An exception are the fans, they have enough space and are in front of all the rest of the engine, allowing the housing of a gearbox within their enclosure. You can find a better discussion about this case in this &lt;a href=&quot;https://aviation.stackexchange.com/q/12753/1467&quot;&gt;question&lt;/a&gt;; keep in mind that here you have 3 compressor stages with only 2 turbine stages, the gearbox was necessary to have a speed differential between fan and IP compressor without requiring 3 turbine stages and an additional shaft. (thanks to @fooot for pointing the PW1000G out)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is this a big deal, does it introduce any serious limitation/drawbacks regarding the exiting air power?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As everything in engineering, there are trade-offs. The ideal performance would be obtained via an infinite set of infinitesimally thin turbines/compressors, each rotating at a slightly different speed, but this is not technologically feasible. The engine designers will then settle for a slightly sub-optimal performance, but it will be actually achievable with 1 or 2 (3 in extreme cases) discrete shafts.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-03-07T20:28:14.903" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25919" PostTypeId="1" CreationDate="2016-03-07T21:41:53.087" Score="6" ViewCount="250" Body="&lt;p&gt;Can software simulations and structural health monitoring techniques accurately predict damage occurrence in aerospace structures using historical data(&lt;code&gt;stiffness,damping and vibration measurements over a considerable period of time&lt;/code&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are these techniques more suited to real time damage detection rather than damage prediction ?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For eg. SHM techniques such as parameter estimation using Frequency Response, or Non Destructive Inspection.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13455" LastEditorUserId="19" LastEditDate="2016-11-21T09:08:59.267" LastActivityDate="2020-04-05T23:21:30.090" Title="Can structural damage be detected or predicted using historical data?" Tags="&lt;aircraft-design&gt;&lt;aircraft-structures&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25920" PostTypeId="1" CreationDate="2016-03-07T22:08:56.613" Score="9" ViewCount="16916" Body="&lt;p&gt;I always thought that the definition of slat was:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Lift modifying and adjustable wing element on the leading edge of main airfoil.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the definition of flap was:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Lift modifying and adustable wing element on the trailing edge of main airfoil.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, there are also leading edge flaps, also known as Krueger flaps, and they are located on the leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What gives these elements the name of &quot;flap&quot;? What is the main difference to slats?&lt;/p&gt;&#xA;" OwnerUserId="935" LastEditorUserId="935" LastEditDate="2016-03-07T22:14:27.847" LastActivityDate="2018-02-17T07:54:35.797" Title="What is the difference between a leading edge flap and a slat?" Tags="&lt;wing&gt;&lt;airfoil&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25921" PostTypeId="2" ParentId="25920" CreationDate="2016-03-07T22:32:34.117" Score="6" Body="&lt;p&gt;Slats are leading edge devices on aircraft that enable higher angles of attack. Flaps are devices on the leading (Krueger) and trailing edge which increase camber and the depth of the wing. Slats create a &quot;slat&quot; between the slat body and the wing leading edge so the air can pass from the bottom to the surface to hold off a stall to a higher AoA, flaps merely extend it fore and aft and direct the flow downwards for more lift. Both are mainly used in the low-speed situations of take-off and landing.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="1961" LastEditDate="2016-03-08T08:03:05.557" LastActivityDate="2016-03-08T08:03:05.557" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25922" PostTypeId="5" CreationDate="2016-03-07T23:22:44.990" Score="0" Body="&lt;p&gt;Fuel lines bring the fuel from the fuel tanks to the engines. It includes the piping as well as all the systems used to monitor and regulate the fuel flow.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-08T00:15:08.570" LastActivityDate="2016-03-08T00:15:08.570" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25923" PostTypeId="4" CreationDate="2016-03-07T23:22:44.990" Score="0" Body="For questions pertaining to aircraft fuel lines, which are the pipes that carry fuel throughout the aircraft." OwnerUserId="12220" LastEditorUserId="1696" LastEditDate="2016-03-07T23:28:36.773" LastActivityDate="2016-03-07T23:28:36.773" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25924" PostTypeId="1" AcceptedAnswerId="25925" CreationDate="2016-03-08T01:43:02.443" Score="6" ViewCount="1093" Body="&lt;p&gt;Many commercial aircraft operated by japanese airlines like JAL and ANA have a red circle on the wing. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6e43v.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6e43v.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Japan-Airlines--/Boeing-777-346-ER/186707/&amp;amp;sid=642aaf8510690405db58594bfcd8d0c1&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;And on this ANA plane, also:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zBJMk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zBJMk.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/All-Nippon-Airways/Boeing-777-381-ER/1505780/L/&amp;amp;sid=5599cde0f980e11a2ee88871be9ef9fa&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Why do they have that red circle there?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-08T07:34:31.913" Title="Why do many commercial aircraft have a red circle on the wing?" Tags="&lt;wing&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25925" PostTypeId="2" ParentId="25924" CreationDate="2016-03-08T01:50:53.840" Score="9" Body="&lt;p&gt;That would be the Japanese sun symbol which also appears on that nation's flag. You can also see that symbol on the tail of that JAL 777 on top.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same as the Japanese Flag:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/5YqaO.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5YqaO.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-08T02:40:39.637" LastActivityDate="2016-03-08T02:40:39.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25926" PostTypeId="1" AcceptedAnswerId="25928" CreationDate="2016-03-08T01:59:39.100" Score="5" ViewCount="589" Body="&lt;p&gt;There is &lt;a href=&quot;https://www.youtube.com/watch?v=2fs9HcdhUFI&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; ATC recording where an A340 pilot requests to leave the aircraft and close the fuel panel on the bottom of the fuselage, while the aircraft is on a taxiway (the request is made at 2:50). Now, here is a picture to show how to get in and out of an A340 without deploying the emergency slides and causing even more issues:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cP63J.jpg&quot; alt=&quot;Avionics bay hatch&quot;&gt;&lt;br&gt;&#xA;(Source: &lt;a href=&quot;http://www.flugzeugbilder.de/show.php?id=695499&quot; rel=&quot;noreferrer&quot;&gt;http://www.flugzeugbilder.de/show.php?id=695499&lt;/a&gt; and yes, I realize this is technically a A330)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the picture also makes it look like it not actually possible for anyone to reach the fuselage from the ground. Is that actually the case? And if so, how &lt;em&gt;would&lt;/em&gt; the pilot actually reach the fuselage and close the fuel panel?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastEditorUserId="7735" LastEditDate="2016-03-08T02:19:33.070" LastActivityDate="2016-03-08T02:26:30.737" Title="Is it possible to reach an A340's fuselage from the ground?" Tags="&lt;airbus-a340&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25927" PostTypeId="2" ParentId="25926" CreationDate="2016-03-08T02:15:03.903" Score="2" Body="&lt;p&gt;As you can see in this image of an A340, there is a person standing under the front who is easily in a hand's reach from the bottom of the fuselage. So yes, the pilot could reach to the bottom of the fuselage to close that panel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nrPJI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nrPJI.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Original Image &lt;a href=&quot;http://www.jetphotos.net/photo/8214816&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another closer view with another person (He is standing a little further away though):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4m5SD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4m5SD.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.jetphotos.net/photo/8213470&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-08T02:18:13.140" LastActivityDate="2016-03-08T02:18:13.140" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25928" PostTypeId="2" ParentId="25926" CreationDate="2016-03-08T02:18:06.800" Score="4" Body="&lt;p&gt;Yes, the refuel/defuel service panel can be reached from a person standing on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Airbus A340-200/-300 &lt;em&gt;Aircraft Characteristics - Airport and Maintenance Planning&lt;/em&gt; document, the height of the panel in question is just under 2 meters from the ground:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2xG9B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2xG9B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The panel is located on the lower area of the wing/body interface fairing as seen here (item 13):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CqFIP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CqFIP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7443" LastEditorUserId="7443" LastEditDate="2016-03-08T02:26:30.737" LastActivityDate="2016-03-08T02:26:30.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25929" PostTypeId="2" ParentId="25914" CreationDate="2016-03-08T02:44:17.410" Score="2" Body="&lt;p&gt;On small aircraft many operators use portable ADS-B IN receivers which typically do not have the ability to sense suppression signals from their own transponder/UAT transmissions and so they will pick up their own signal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most installed systems have that suppression functionality so this won't happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The suppression is simply a wire between the two units that if the transmitter is transmitting, it goes high, which tells the receiver to ignore whatever it is receiving at the moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you want to &quot;receive&quot; yourself, simply snip the suppression wire if you have one...&lt;/p&gt;&#xA;" OwnerUserId="340" LastActivityDate="2016-03-08T02:44:17.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25930" PostTypeId="2" ParentId="25861" CreationDate="2016-03-08T04:23:45.717" Score="1" Body="&lt;p&gt;As stated in another response the stock engine in a C172 isn't powerful enough to sustain Vne in horizontal flight.  Establishment of the various speeds is part of the aircraft certification process and usually includes a safety margin of 10 to 15 percent and there are many factors that go into determining these numbers.  For example, I have a Beachcraft Baron and one of the important speeds is Vr or V Rotate.  It's not that the aircraft cannot take off at a slower speed it's just that if you have a critical engine failure at takeoff power and a slower speed you don't have enough control authority to compensate.  There are many factors that go into determining these numbers and structural integrity is just one of them.&lt;/p&gt;&#xA;" OwnerUserId="13910" LastActivityDate="2016-03-08T04:23:45.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25931" PostTypeId="1" CreationDate="2016-03-08T04:47:30.660" Score="2" ViewCount="315" Body="&lt;p&gt;I was recently on a transatlantic flight and watched the movie &lt;a href=&quot;https://en.wikipedia.org/wiki/Steve_Jobs_(2015_film)&quot; rel=&quot;nofollow&quot;&gt;Steve Jobs&lt;/a&gt; on the plane’s entertainment system. Every movie I tried, including that one, had a message right at the start saying the movie had been edited for content.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In one scene, the caracter of Steve Wozniak is fiddling with a watch and the character of Steve Jobs makes a joke it looks like he’s messing with a bomb. Those words were muted. The word “bomb” (and one or two words around it) were gone from the movie. I even rewinded to make sure, and the words were indeed gone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there some weird law that forbids the use of the word in inflight entertainment systems? It there is, it’d be particularly weird since you need to plug headphones to listen to the movie in the first place, so it’s unlikely you’d cause hysteria. In addition, the word was pronounced again later on in the movie but wasn’t muted then. It was less clear audibly, though, so it’s feasible it wouldn’t have been caught by the automated system (if any is used).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airline was &lt;a href=&quot;http://www.flytap.com/&quot; rel=&quot;nofollow&quot;&gt;TAP&lt;/a&gt;, and the entertainment systems are individual per seat.&lt;/p&gt;&#xA;" OwnerUserId="13912" LastEditorUserId="13912" LastEditDate="2016-03-10T02:40:25.770" LastActivityDate="2016-03-10T02:40:25.770" Title="Is the word “bomb” muted in inflight movies?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ClosedDate="2016-03-08T07:57:35.903" ContentLicense="CC BY-SA 3.0" />
  <row Id="25932" PostTypeId="2" ParentId="25931" CreationDate="2016-03-08T06:01:49.977" Score="0" Body="&lt;p&gt;This might be dependent on the airline?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I usually fly Emirates and the movies are not muted for the word &quot;bomb&quot;. Maybe because each seat has its own entertainment console?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the old days when there was one giant projector that displayed movies (which was later replaced by TVs that articulated from the ceiling) - I suppose in these scenarios it might be prudent to mute words or scenes.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-03-08T06:01:49.977" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25933" PostTypeId="1" AcceptedAnswerId="25935" CreationDate="2016-03-08T07:08:28.777" Score="8" ViewCount="13741" Body="&lt;p&gt;Is it sensible to harness wind energy on an airplane? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actually the idea is to build an electric aircraft whose power comes from solar and from wind while the plane is landing. instead of using spoilers as airbrakes, these wind turbines separately mounted could add drag and harness energy at the same time . In other words, regenerative braking.&lt;/p&gt;&#xA;" OwnerUserId="13915" LastEditorUserId="1467" LastEditDate="2016-03-08T09:11:26.830" LastActivityDate="2018-02-06T04:10:51.563" Title="Is it sensible to harness wind energy on an airplane?" Tags="&lt;landing&gt;&lt;wind&gt;" AnswerCount="11" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25934" PostTypeId="2" ParentId="25924" CreationDate="2016-03-08T07:34:31.913" Score="-1" Body="&lt;p&gt;May be another example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emirates airline:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mB6R0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mB6R0.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the flag of the United Arab Emirates:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kna6q.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kna6q.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2016-03-08T07:34:31.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25935" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T07:41:05.693" Score="24" Body="&lt;p&gt;Normally not: Extracting energy from the airflow produces drag, which must be overcome by added thrust. Since every form of energy conversion produces losses, more thrust energy must be added than can be gained from the airflow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only when the engines fail and the generators stop running does it make sense to extract energy from the airflow. In airplanes there are two applications which are driven by &quot;wind energy&quot;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Older airplanes use gyros for the artificial horizon which are powered by ram air. This way the gyros work even after an engine failure.&lt;/li&gt;&#xA;&lt;li&gt;Jets use Ram Air Turbines (RAT), propeller-driven generators which are moved into the airflow when all other means of generating electricity and hydraulic power have failed. Note that this is done in unpowered flight and increases the sink rate.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LQ1L7.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LQ1L7.jpg&quot; alt=&quot;Deployed RAT&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Deployed RAT (picture &lt;a href=&quot;http://4.bp.blogspot.com/-bR2dfvdSc5s/VSMb6eAR0DI/AAAAAAAANvw/54Kj97BZ5Kg/s1600/aero_rat_ram_air_turbine_06.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rocket-powered airplanes have no easy way to generate electricity, so the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet#Me_163B&quot; rel=&quot;noreferrer&quot;&gt;Me-163 B&lt;/a&gt; used a small windmill at the tip of the fuselage to drive a generator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PPuRM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PPuRM.jpg&quot; alt=&quot;Me-163 B&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Me-163 B (picture &lt;a href=&quot;http://www.deutscheluftwaffe.de/Flugzeuge/Jeager/Me163/me163-017.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&#xA;With your question's new focus on electric propulsion the answer will become different. Now you most likely will have propellers which are powered by electric motors. During landing, those could run inverted and charge a battery, which will most likely be empty by the time the aircraft lands. This can be done during final approach until the end of the runout after touchdown. It can be expected that any electric airplane will have a high L/D, so deploying speed brakes to allow for a steeper approach makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would be surprised if an additional device would be economical, however. This recharging must be done by the regular propulsion system, or it would add dead weight during most of the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You asked for formulas, but all I can provide here are some back-of-the-envelope calculations. First, it must be said that variable-pitch propellers will be lousy as windmills, because their camber and twist are wrong for windmilling mode. I would expect that their efficiency is around 30%, which means that only 30% of the energy extracted by drag will be converted into mechanical energy which drives the electric motor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, &lt;a href=&quot;https://www.physicsforums.com/threads/electric-motor-used-as-generator.435164/&quot; rel=&quot;noreferrer&quot;&gt;running an electric motor as a generator&lt;/a&gt; will again require compromises. Good motors make poor generators, and re-wiring the motor for better generator performance will degrade its efficiency in normal use. You will quickly lose more than you gain from the short flight phase when running the motor inverted makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's assume that you keep your propulsion system at top efficiency (say, 90%) and accept that it will only convert 10% of the drag energy into electric energy. Let's also assume that your prospective solar airplane has an L/D of 30 which needs to be reduced to 10 for a practical approach. You do this from 1000 ft downwards and use the windmilling propeller also during the runout. Approach speed is $v$, mass is $m$ and the initial energy of the airplane is $305\cdot m\cdot 9.81 + \frac{m}{2} \cdot v^2$. Two thirds of the potential energy go into propeller drag, and to be generous we assume that 100% of the kinetic energy will also go into propeller drag, even though the braking force of the propellers at low speed is really lousy and needs support from wheel brakes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it is important how fast your airplane flies, because this will shift the ratio between potential and kinetic energy. To keep things simple, I will relate both to the energy required for the next flight. 10% of the full kinetic energy will accelerate the aircraft to less than one third of its flight speed - after this, the remaining 91% of the energy to reach $v$ must be added by charging the batteries between flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electric energy taken from the potential energy will help you climb to 60ft or sustain level flight at $v$ for a distance of 1800ft. At an L/D of 30 the airplane will fly a distance of 30,000ft without thrust, and by braking you will extract the energy to cover 20,000ft, which at 10% conversion efficiency (and 90% propulsion efficiency!) will carry you over just 1800 ft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-09T20:00:52.293" LastActivityDate="2016-03-09T20:00:52.293" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="25936" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T07:52:07.890" Score="10" Body="&lt;p&gt;No, because, from the point of view of a flying aircraft, wind does not have any energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind turbines stand on the ground and the air mass is moving at some velocity past them, so it has kinetic energy. But aircraft is moving relative to the wind, so the wind is the rest frame and has no energy. So when the aircraft is using the air flow and/or ram air pressure, it is using &lt;em&gt;its&lt;/em&gt; energy, not the wind's¹.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now of course a turbine mounted on aircraft &lt;em&gt;will&lt;/em&gt; produce energy. But it will be at expense of the aircraft energy. When flying level under power, the power comes from the engines, so it is more efficient to extract it directly via generator mounted on the accessory drive. But even when the aircraft is descending on idle, it will be at expense of its potential energy and that was originally provided by the engines during climb. Shutting down the engine earlier and using all of it to compensate for drag during the glide is more efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This applies to a solar powered motor glider just like any other plane. It is more efficient to stop the engines earlier and glide at around best glide angle than running the engines longer and then regenerating the energy, because neither conversion from electric energy to potential energy via engine and propeller, nor the conversion from potential energy to electric energy via turbine and generator is particularly efficient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And it applies even when using thermals or other raising air to gain potential energy. It is again more efficient to avoid converting the energy and simply use the thermal to gain altitude and extend the glide while taking electric energy directly from the solar panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, weight will be important limiting factor for solar motor glider. This means you won't be able to put many batteries on board and that in turn means that regenerative braking won't be very useful as you won't have much capacity to store the energy. It also means you might want to avoid dedicated turbine to save weight; you'll still be able to regenerate some energy from windmilling propellers at somewhat lower efficiency. But as explained, it does not make all that much sense.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The only time aircraft use turbines is during emergency. When all engines fail, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot;&gt;ram air turbine&lt;/a&gt; is used to power the essential electric and hydraulic systems. It shortens the gliding distance a bit, but it is worth it if no other power sources are available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as wind goes, the only practical use of wind is choosing route so that there is as much tail wind during cruise as possible. For example the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot;&gt;North Atlantic Tracks&lt;/a&gt; are periodically adjusted to allow the eastbound flights to utilize the &lt;a href=&quot;https://en.wikipedia.org/wiki/Jet_stream&quot;&gt;Jet Stream&lt;/a&gt;. In a sense, this utilizes the wind energy, because the aircraft thus burns less fuel to get to its destination.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Energy is a weird quantity. It is conserved in all inertial reference frames, but some of its forms will have different values in each. You can choose a reference frame where wind does have energy, but it will make less sense.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-08T09:40:23.977" LastActivityDate="2016-03-08T09:40:23.977" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="25937" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T08:52:31.893" Score="4" Body="&lt;p&gt;For the reasons other answerers have said, it isn't &lt;em&gt;normally&lt;/em&gt; worthwhile, because it isn't really wind energy, it's the aircraft's energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One situation where it is worthwhile is to generate electricity when it is difficult to take energy from the engine directly. For example, the vintage aircraft I fly didn't originally have an electrical system. To power their radios and transponders (essential for practical flight nowadays), they've been retrofitted with a small turbine under the nose. It increases the drag of the aircraft slightly, but the alternative would be trying to fit an alternator to a vintage engine, or replacing the engine completely, both much bigger modifications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also seen touring aircraft which use small wind generators when they're tied down on the airfield, presumably to keep the battery topped up. The generator in that case is a small wind turbine atop a vertical pole, similar to what you might see on a houseboat or a caravan. They're removed and stowed before flight, so they're not quite what you're thinking of, but they're still aircraft using wind power.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-03-08T08:52:31.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25939" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T10:54:15.933" Score="0" Body="&lt;p&gt;The normal way to harness the energy of the air in an aircraft is a &lt;em&gt;glider&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_%28soaring%29&quot; rel=&quot;nofollow&quot;&gt;wikipedia article&lt;/a&gt; covers it pretty well: find an area where the air is rising, and use it to lift the aircraft up. There is no fancy energy conversion on the aircraft, it's all done directly by the lifting surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.solar-flight.com/home/&quot; rel=&quot;nofollow&quot;&gt;Solar-powered planes have been built&lt;/a&gt;, although the necessary compromises mean they're not yet popular. Some tech companies are looking at the possibility of high-endurance automated solar aircraft as radio relays for connecting remote areas to the Internet.&lt;/p&gt;&#xA;" OwnerUserId="7776" LastActivityDate="2016-03-08T10:54:15.933" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25940" PostTypeId="1" CreationDate="2016-03-08T11:02:52.163" Score="3" ViewCount="2196" Body="&lt;p&gt;Why, for jet airplane design, does maximum Mach (or maximum speed) affect thrust-to-weight ratio so strictly? (as you can see for example in Daniel P. Raymer &quot;Aircraft Design: A conceptual Approach&quot; Table 5.3 page 80, where you can find $\frac{T}{W_o}=a\cdot M_{max}^C$, where “$a$” and “$C$” are empirical factors, for jet transport $a=0.267$ and $C=0.363$)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just now I did notice to detail that Raymer say : &quot;The equations were developed by the author using data from Ref 1&quot; Ref1: i.e. the famous annual book : &quot;Jane's All the world Aircrafts&quot; . But anyway &quot;maximum speed&quot; (or maximum Mach number) in this case the maximum speed is ...the speed that the aircraft is not able to exceed  or.... the speed that is forbidden for the pilot to try to exceed because it can be dangerous? Because, if it's the first case it's more understandable; in fact, if the other parameters are fixed, with the same fixed distance, if T/W is low the acceleration is lower and so before the end of the distance, you can arrive to low speed. At the opposite if T/W is high the acceleration is higher and so before the end of the distance, you can arrive to high speed. What do you think? So, in Janes book, what is the definition of Maximum Mach number?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="13498" LastEditDate="2016-05-09T14:27:13.737" LastActivityDate="2020-04-14T13:32:02.750" Title="Why does thrust-to-weight ratio depend from max Mach number?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25941" PostTypeId="1" AcceptedAnswerId="25943" CreationDate="2016-03-08T11:31:33.880" Score="3" ViewCount="608" Body="&lt;p&gt;News of the potential further stretch of the A350-1000 have seen pretty much all journalists discuss the &quot;high performance characteristics&quot; of the competing Boeing 777-9 with Middle Eastern airlines. &lt;a href=&quot;http://fortune.com/2016/03/04/airbus-weighs-new-400-seat-jetliner/&quot; rel=&quot;nofollow&quot;&gt;For example&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[...] the new Airbus jet would target airlines that need high-capacity, long-range aircraft but not necessarily require the same high-performance characteristics that have made the 777-9 so popular with Middle Eastern airlines. (The Gulf region can be hard on an airliner.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What exactly are these? Why is the 777-9 suited to them and the A350 not?&lt;/p&gt;&#xA;" OwnerUserId="13369" LastEditorUserId="13754" LastEditDate="2016-03-09T23:46:27.030" LastActivityDate="2016-03-09T23:46:27.030" Title="What are the &quot;high performance characteristics&quot; of a Boeing 777?" Tags="&lt;boeing&gt;&lt;airbus&gt;&lt;boeing-777&gt;&lt;airbus-a350&gt;&lt;economics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25942" PostTypeId="2" ParentId="25715" CreationDate="2016-03-08T11:51:10.243" Score="3" Body="&lt;p&gt;No, you cannot make an entire model jet engine out of aluminium.&#xA;Most fuels burn at 1000+C and aluminium melts at around 660C: Even if you keep the burning contained in airflow (thus away from the walls) the heat transfer will still damage the aluminium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could make the majority of the engine from it, though: Just as long as you find something more suitable for the 'hot' parts.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-03-08T11:51:10.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25943" PostTypeId="2" ParentId="25941" CreationDate="2016-03-08T12:03:50.403" Score="4" Body="&lt;p&gt;The gulf region is very hot, something that can reduce aircraft performance. The 777-9 is better able to cope with that (due to the higher thrust from the engines and larger wing area).&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-03-08T12:03:50.403" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25944" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T12:11:57.200" Score="13" Body="&lt;p&gt;Most other answers focus on normal flight; your (updated) question specifically asks about regenerative braking. In theory, &lt;strong&gt;yes&lt;/strong&gt;, it's possible, in practice, &lt;strong&gt;no&lt;/strong&gt;, it's really not a practical idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's first focus on the descent from cruise altitude to final approach. Ideally, this descent is done with engines on their lowest thrust setting (flight idle), which means the engines are providing power to the various electric and hydraulic systems, and pressurization, and a little bit of thrust since you can't really avoid that on a jet. Theoretically, this could be done by a Ram Air Turbine (let's for now assume that our hypothetical airplane is equipped with a rather big version that comfortably powers all aforementioned systems, since a typical RAT can only provide limited emergency power). However, this will greatly increase the drag, and to maintain speed, the descent profile will be steeper. This in turn means that the airplane must spend a longer time at cruise altitude, which requires energy to maintain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to look at that is by a simple energy balance: there is a finite amount of potential energy, and it doesn't really matter whether you use it to maintain speed only, or whether you use it to maintain speed &lt;strong&gt;and&lt;/strong&gt; for regenerative braking, since the total amount of energy you can extract from it is always the same. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, there is one moment that airplanes &lt;strong&gt;must&lt;/strong&gt; brake, and this is after touchdown. Let's for now assume that we are very environmentally aware, and do not use any other means of braking than a regenerative braking system. The airplane is still going at about, say, 130kts, 240km/h or 150mph, so surely that will give us &lt;strong&gt;a lot&lt;/strong&gt; of energy? Let's make a back-of-the-envelope calculation for some &lt;a href=&quot;http://www.b737.org.uk/vspeeds.htm#Landing_V_Refs_&quot; rel=&quot;nofollow&quot;&gt;figures I found&lt;/a&gt; for a Boeing 737-300.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say we land weighing 60 000kgs (close to MLW) with flaps reduced to 15, which gives us a landing speed of 158kts=81,3m/s. The amount of kinetic energy is then $\frac{1}{2}mv^2\approx200 MJ$ (yes, that's mega-joules!). That's a lot of energy, right?! Well... not really. Kerosene (which is approximately the same as jet fuel) comes at an energy density of around 46MJ/kg. We're talking about the equivalent of a little over 4kg of kerosene, on an aircraft that carries about 16,000kg of the stuff. That means we're regenerating about &lt;strong&gt;0.025%&lt;/strong&gt; of the fuel capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will leave it as an exercise to the reader to think whether a regenerative braking system could be designed, such that the extra fuel used due to its weight and size is under 0.025%. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt; Let's redo the calculation on an airplane that actually has most of the necessary equipment (batteries and electric motors that could perhaps double as alternators or dynamos) on board: the Solar Impulse 2. It has a whopping 4x41kWh battery capacity (590MJ). Assuming the takeoff and landing speed are the same (20kts=36km/h=10m/s) and with a loaded weight of 2300kg, the kinetic energy upon landing is 115kJ. This is 0.0195% of the battery capacity - about the same as our B733 example! And note that this is again assuming that the propellers recover 100% of the kinetic energy... &lt;strong&gt;This idea is never going to work.&lt;/strong&gt; (For comparison, it's less than two seconds of energy generated by the solar panels at their respective peak rating)&lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2016-03-09T10:57:46.243" LastActivityDate="2016-03-09T10:57:46.243" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="25945" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T12:12:11.933" Score="1" Body="&lt;p&gt;Airplanes move pretty fast (in some cases &lt;em&gt;very&lt;/em&gt; fast) and have lots of drag. So they use lots of energy just to cruise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regenerative braking allows you to capture, as an absolute upper limit, all the kinetic energy and gravitational potential energy that the plane has when it starts its descent (obviously there's then an efficiency consideration too, so it will actually be less than this). The work you've done during the flight just to overcome drag at cruising speed is gone no matter what. So first thing: any drag that your doohickey adds to the plane while it's not braking, is costing energy through the whole flight. Let's assume that it's somehow stowed away, just like landing gear can be, and figure that it's going to bulk the plane up a bit but it isn't going to totally ruin the aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, on a typical flight what proportion of the fuel used, is used to reach cruising altitude and speed? I don't actually know, and of course it depends on the length of the flight among other things, but I'm sure some actual pilots could chip in with rough figures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The energy to get up is an upper limit (again, there's inefficiency in the engines) on how much energy you can extract from the process of getting down. So, that proportion of fuel used to get up puts an absolute upper limit on the proportion by which regenerative braking can possibly reduce the total energy requirements of your solar-powered plane. And that's before considering inefficiencies of both processes (the engines and the regenerative brakes). So to completely invent some figures, supposing take-off is 25% of fuel for some particular journey, and combined efficiency is 50%, then regenerative braking could perhaps reduce energy requirements by 12.5%. This seems worthwhile on the face of it, but (a) I've picked what I think are overly-large numbers, and (b) we haven't yet paid for the mechanism that does it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can the batteries (or whatever) that store the energy from the brakes, store more energy than it costs to add them to the plane, thereby hauling a larger weight up to altitude in the first place, and the energy lost in cruise to the extra drag imposed by incorporating the whole system? In the worst case where they can't, you've made a net loss by adding regenerative braking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regenerative braking works reasonably well for cars, especially in city driving, because they slow down frequently and so they're otherwise dispersing a lot of unwanted kinetic energy as heat. To a rough approximation, planes only slow down once per trip. And I believe it's harder to efficiently capture the energy when you're braking against air rather than against static friction on the road, and so the efficiency of the system on the plane will be &lt;em&gt;much&lt;/em&gt; less than that for a car. So I don't think your plan is in good shape right now :-)&lt;/p&gt;&#xA;" OwnerUserId="966" LastEditorUserId="966" LastEditDate="2016-03-08T12:32:06.013" LastActivityDate="2016-03-08T12:32:06.013" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25946" PostTypeId="1" CreationDate="2016-03-08T13:11:47.987" Score="7" ViewCount="1593" Body="&lt;p&gt;Loss of static and pitot tubes affect the display of airspeed, altitude, vertical speed information. Loss of this information can  be catastrophic for flight. How are the pilots communicated about the failure of these ports (ex: when they get blocked). Or is there a system in place already that detects the blockage and unblocks it. Even if such system exists, what is done to ensure that pilot does not trust the airdata information displayed during the time when the ports are blocked?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2018-06-01T21:34:35.073" Title="Is it possible to detect a pitot static failure (blockage) of air data probe during flight and alert the pilot?" Tags="&lt;pitot-static&gt;" AnswerCount="5" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25947" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T13:37:48.540" Score="3" Body="&lt;p&gt;I think no one really adressed your question. I'll try to, as far as I understood. (I still wonder why you need a plane landed with non-empty batteries, but let's assume it's for faster refuel &amp;amp; takeoff?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, it is only possible to harvest wind energy (of air moving w.r.t. ground) if you have access to the ground.(You need to be a the interface between the two moving objects). A wind turbine must be grounded, a sail boat is in contact with the water, etc. For an aircraft this is not the case obviously, so as said in other answers &lt;strong&gt;it is impossible to gather free wind energy mid-flight&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, &lt;strong&gt;it &lt;em&gt;is&lt;/em&gt; possible to use windspeed to harvest some of the &lt;em&gt;aircraft&lt;/em&gt;'s energy&lt;/strong&gt;. Let us recall there are three main energy tanks in an aircraft (i'll use &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320_family#A320&quot; rel=&quot;nofollow&quot; title=&quot;A320&quot;&gt;A320&lt;/a&gt; and &lt;a href=&quot;https://fr.wikipedia.org/wiki/Socata_TB-20&quot; rel=&quot;nofollow&quot; title=&quot;TB20&quot;&gt;TB20&lt;/a&gt; (sorry french link for numbers) both in cruise in a regular mission, it would scale nicely for any e-aircraft):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Kinetic energy (momentum) - A320=2.2GJ / TB20=3.5MJ&lt;/li&gt;&#xA;&lt;li&gt;Potential energy (its height in the earth gravity field) - A320=7.7GJ / TB20=66MJ&lt;/li&gt;&#xA;&lt;li&gt;Fuel energy (required to cover least 1000 n.m. against the drag force, plus the above) - A320=180GJ. / TB20=1000MJ&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As you can see, fuel energy in a classic airplane really dwarfs potential energy about 20-to-1, and potential surpasses kinetic about 10-to-1. It's the travelling part that costs the most, and unfortunately, airplanes are kinda designed expressedly for travel :D&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since &lt;strong&gt;what you used to travel (against the drag) can never be recovered&lt;/strong&gt;, only the surplus kinetic and potential at the end of the mission may be. You propose to perform the descent and landing with the wind turbines. Let's suppose you have the wind turbine for the job. You may only re-gather kinetic energy during approach and landing, and potential energy during descent at constant-speed.&#xA;Even if you manage to recover the whole energy, &lt;strong&gt;you only get ~5% of what you used in your whole mission!&lt;/strong&gt; (and i used 100% efficiency everywhere, full system should be close to 20% efficient including turbine, generators, power unit, batteries etc. so we're really speaking about 1% net energy return).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;That said, &lt;strong&gt;there &lt;em&gt;might&lt;/em&gt; be a use for a windspeed turbine&lt;/strong&gt; in &lt;em&gt;very&lt;/em&gt; specific missions, but you would prob. drop the solar panels. I'm thinking parachuting planes. Mission: go high very quickly, drop your buddies, descend, repeat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this the energy demand isn't very high since you're not &lt;em&gt;travelling&lt;/em&gt;.&#xA;I'm thinking a mission requirement of 2x pot. energy to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Get to speed&lt;/li&gt;&#xA;&lt;li&gt;Climb to altitude&lt;/li&gt;&#xA;&lt;li&gt;Beat the drag while climbing but not travelling&#xA;Then you'll have 1x pot. energy + 1x kinetic energy to recover, and the numbers change a bit: there is 50% of energy available to recover, so with 20% efficiency, about 10% of the whole input can be brought back down.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm saying drop the solar panels, because this will be very power-intensive, and&#xA;solar panels just have too low energy density&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; energy density of a system is energy packed/mass on board. For batteries and fuel this is straight forward, for solar panels it's different: the longer the mission, the more energy produced, the higher the power density. This mission is so short it's not worth it.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; : Unless you have a very weird mission, there just isn't enough energy (~1%) to collect to be worth bringing a few wind turbines for a whole travelling mission.&lt;/p&gt;&#xA;" OwnerUserId="13917" LastActivityDate="2016-03-08T13:37:48.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25948" PostTypeId="1" AcceptedAnswerId="25949" CreationDate="2016-03-08T13:43:51.700" Score="20" ViewCount="6083" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/questions/25926/is-it-possible-to-reach-an-a340s-fuselage-from-the-ground&quot;&gt;this&lt;/a&gt; question, there is an image of a ladder leading to some hole in the bottom of the nose of an A330. What is that hole for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qOPBi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qOPBi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flugzeugbilder.de/show.php?id=695499&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-03-09T13:41:51.193" Title="What is this hole in the nose of the A330?" Tags="&lt;airbus-a330&gt;&lt;nose&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25949" PostTypeId="2" ParentId="25948" CreationDate="2016-03-08T13:51:10.027" Score="31" Body="&lt;p&gt;It is the avionic compartment access door as described in the &lt;a href=&quot;http://www.google.de/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=9&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwi21JGinbHLAhXLkywKHRofDukQFghFMAg&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DA330-Doors.pdf&amp;amp;usg=AFQjCNGKxE3TjwqtDoRrEkB4bK_1O_po9A&amp;amp;sig2=pfYXX8zavoCn8YlIM1U3fw&quot; rel=&quot;noreferrer&quot;&gt;Flight Crew Operating Manual&lt;/a&gt;!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An inward-opening, manually operated, hinged door gives access to the avionics compartment. This door is in the lower fuselage, forward of the nose landing gear bay. A ladder is stowed inside the compartment adjacent to this door, which may be either be operated from the interior or the exterior.&#xA;  This compartment is also accessible from the cockpit, via a floor hatch located behind the Captains' seat. A fixed ladder in the avionics compartment for access from the cockpit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is a drawing from the outside!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lg9ke.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lg9ke.png&quot; alt=&quot;[A330 Avionics Hatch&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And here a view from the cockpit flight deck for an A340!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pEV63.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pEV63.png&quot; alt=&quot;A340 Flight deck Layout&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="8359" LastEditDate="2016-03-08T20:10:09.370" LastActivityDate="2016-03-08T20:10:09.370" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25950" PostTypeId="2" ParentId="25948" CreationDate="2016-03-08T13:56:00.070" Score="13" Body="&lt;p&gt;That 'hole' gives access to the avionics comparment- forward zone. The comparment has a ground access ladder, which is seen in the image. The deployment of that ladder (which is similar in A330/A340) can be seen in &lt;a href=&quot;https://www.youtube.com/watch?v=eKrHO6a04Cw&quot; rel=&quot;nofollow&quot;&gt;this video&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3394" LastEditDate="2016-03-09T13:41:51.193" LastActivityDate="2016-03-09T13:41:51.193" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25951" PostTypeId="5" CreationDate="2016-03-08T14:38:28.887" Score="0" Body="&lt;p&gt;The nose is the forward part of the plane which contains the cockpit and many avionics equipment.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-08T14:54:49.750" LastActivityDate="2016-03-08T14:54:49.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25952" PostTypeId="4" CreationDate="2016-03-08T14:38:28.887" Score="0" Body="For questions about the nose of aircraft." OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-08T15:13:38.060" LastActivityDate="2016-03-08T15:13:38.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25953" PostTypeId="2" ParentId="25946" CreationDate="2016-03-08T14:53:51.747" Score="4" Body="&lt;p&gt;Some planes are set up with &lt;a href=&quot;https://en.wikipedia.org/wiki/Triple_modular_redundancy&quot; rel=&quot;nofollow noreferrer&quot;&gt;triple redundancy&lt;/a&gt; (often found on &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_control_modes&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus planes&lt;/a&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/udchq.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/udchq.png&quot; alt=&quot;Diagram of air data systems&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/ff/Airspeed_indication_system_-_fly_by_wire.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case the system can reject the bad reading (caused by a blockage or bad probe etc.) by using the data from the 2 other sensors. The basic logic is that if all 3 probes are in agreement (same reading) they are all working. If at any given time one of the probes readings differs from two of the others then the reading is rejected. Of course this does open you up to the issue where two of the 3 probes fail and only a single probe is correct. However the chances of two probes failing and giving the same incorrect reading is low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In modern planes things like GPS and INS units can be used to cross check the system but it will not necessarily be connected to all the same systems. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know of any system that unblocks a pitot tube if a physical blockage is present, but if this is in reference to Air France 447, modern airplanes have a heater that can be applied to pitot tubes to de-ice them.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1696" LastEditDate="2016-03-08T16:39:05.003" LastActivityDate="2016-03-08T16:39:05.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25954" PostTypeId="2" ParentId="25933" CreationDate="2016-03-08T15:06:55.163" Score="0" Body="&lt;p&gt;&lt;strong&gt;Very Short Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it sensible to harness wind energy on an airplane? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I assume as &quot;wind energy&quot; you mean, extracting energy from the &quot;airflow&quot;. In theory yes, only in descent, if you can prove a design which brings benefits in terms of energy, complexity, economics. In practice, you have &lt;em&gt;very&lt;/em&gt; slim margins with your solution, and only &quot;&lt;strong&gt;one case&lt;/strong&gt;&quot; when harvesting energy makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Little Longer Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's analyze the idea:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... to build an electric aircraft whose power comes from solar and from wind while the plane is landing. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the airplane is landing it is descending from &quot;cruise&quot; altitude to the airport. In theory it would need no &quot;extra power&quot;, since you have a lot of potential energy, you could just use this potential energy to &quot;&lt;em&gt;glide&lt;/em&gt;&quot; to the airport, similar on what sailplanes do. An &lt;strong&gt;important note&lt;/strong&gt; the energy to get to &quot;cruise&quot; altitude has already been spent, for example, what Solar Impulse 2 do is to &lt;em&gt;climb&lt;/em&gt; and &lt;em&gt;recharge&lt;/em&gt; the batteries during the day, and &lt;em&gt;glide&lt;/em&gt; and use the &lt;em&gt;energy-from-the-batteries&lt;/em&gt; during night. &#xA;Don't underestimate the efficiency of the gliding maneuver over night, with altitude you gain a lot of potential energy! You would not gain the same energy by harvesting it to from the airflow because you are transforming this potential energy in electrical energy with a transformation chain that bring you some losses.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, the &lt;strong&gt;one case&lt;/strong&gt; when makes sense to harvest energy in descent is the moment that you need to loose some altitude in a &quot;short&quot; period of time, (not &lt;em&gt;glide&lt;/em&gt; to the ground, which would be the most efficient solution). In this case it is desirable and possible to &quot;&lt;em&gt;harvest&lt;/em&gt;&quot; some energy, what you are proposing is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;instead of using spoilers as airbrakes, these wind turbines separately mounted could add drag and harness energy at the same time . In other words, regenerative braking.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is correct, it is done in a similar way with &lt;a href=&quot;https://en.wikipedia.org/wiki/Ram_air_turbine&quot; rel=&quot;nofollow&quot;&gt;Ram Air turbines&lt;/a&gt; in emergency situations (no power) on larger jets. On a variable-pitch propeller aircraft theoretically you could change the pitch of the propeller to make them work as windmills, so that you would not need to add extra complexity and weight. If you have an electric motor driving the propellers you could potentially using it as a generator.&#xA; In case you add &quot;wind turbines&quot;, or any extra system, you should make sure that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The energy to fly the extra weight of the system during all the mission is less that the energy that the system helps you harvesting&lt;/li&gt;&#xA;&lt;li&gt;The cost of the harvested energy helps you breaking even the cost of the system in a reasonable amount of time.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A last note: Spoilers are use not only to add drag but even to &lt;em&gt;reduce lift&lt;/em&gt;, the main use case here is descent (emergency or not)!&lt;/p&gt;&#xA;" OwnerUserId="13754" LastActivityDate="2016-03-08T15:06:55.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25955" PostTypeId="2" ParentId="25946" CreationDate="2016-03-08T15:39:03.423" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Loss of this information can be catastrophic for flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is certainly a risk factor, but pilots have to do many mistakes before it really becomes catastrophic. There are procedures to get the plane safely to the ground even without that information.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How are the pilots communicated about the failure of these ports (ex: when they get blocked).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Failure of the ports specifically, rather than the system as a whole, can't be detected and if it can't be detected, it can't be communicated either. So it isn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft with three redundant systems and flight computer have the computer compare the readings and display appropriate message (airspeed disagree, altitude disagree, vertical speed disagree) and sound master warning if it detects mismatch larger than normal measurement error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In smaller aircraft that don't have redundant pitot-static systems (light singles usually don't) and in older aircraft without flight computer it is up to the pilot(s) to spot the problem.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Or is there a system in place already that detects the blockage and unblocks it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It is not possible to detect the blockage. The only unblocking mechanism is anti-ice, which simply heats the pitot tube to prevent ice buildup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only the pitot port, which faces forward, can be blocked in flight. The static ports face sideways and are almost impossible to get blocked in flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Even if such system exists, what is done to ensure that pilot does not trust the airdata information displayed during the time when the ports are blocked?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Nothing. Even if the system does detect a fault by comparing the values from the separate system, it does not know which of the systems is wrong. The pilots must decide themselves by combining other information they have and their understanding of physics of flight. They have pitch-power tables and other &lt;a href=&quot;https://aviation.stackexchange.com/questions/15681/standard-procedure-in-case-of-inconsistent-sensor-readings&quot;&gt;procedures&lt;/a&gt; to diagnose the problem.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-08T15:39:03.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25956" PostTypeId="1" CreationDate="2016-03-08T17:28:17.017" Score="0" ViewCount="174" Body="&lt;p&gt;As you can see in the below image the front landing gear is retracting forwards, meaning that it extends forwards. What is the reason why they are made to drop backwards instead of forwards?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/10dvM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/10dvM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Qantas/Airbus-A380-842/2788797/L/&amp;amp;sid=5d45b4f56c689507c38c7ad60fd13eb1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-08T17:28:17.017" Title="Why does landing gear extend backwards and retract forwards?" Tags="&lt;landing-gear&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2016-03-08T17:46:39.953" ContentLicense="CC BY-SA 3.0" />
  <row Id="25957" PostTypeId="2" ParentId="25852" CreationDate="2016-03-08T17:35:18.690" Score="2" Body="&lt;p&gt;Seems like the hard way to see the world.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming you have a private license with complex and retractable endorsements. Then the next step is to get your instrument rating, multi engine, turbine and commercial ATR rating and at least 800 to a thousand hours as PIC (Pilot in Command). By now you have spend over $50,000 and might be employable as first officer for a small low budget commuter line at a couple of G's a month.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it worth it? That's up to you. I have over 4,000 hours in single and multi engine prop and jet aircraft. I own and fly a Beech Baron which is considered to be one of the more challenging light twin engine planes. I do not consider myself qualified to be an airline pilot.&lt;/p&gt;&#xA;" OwnerUserId="13911" LastEditorUserId="65" LastEditDate="2016-04-07T18:14:37.073" LastActivityDate="2016-04-07T18:14:37.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25958" PostTypeId="1" CreationDate="2016-03-08T17:36:11.617" Score="0" ViewCount="358" Body="&lt;p&gt;In some fly by wire systems I found that there is no trim in the traditional sense. I believe it is because the forces that pilot feels on the stick are artificial. I was told that those fly by wire systems has elevator offload functionality that moves H-stab.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Can anyone explain how elevator offload functionality is implemented?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the artificial feel system generate force in response to airspeed and vertical acceleration? (like making pilot push harder for every knot/every G away from the trimmed state?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is trimming necessary for FBW systems and if so How does the fly by wire system implements the trim?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="12220" LastEditDate="2016-03-08T17:42:12.663" LastActivityDate="2016-03-08T19:42:05.220" Title="How does an elevator offload function works in fly by wire flight control systems?" Tags="&lt;trim&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2016-03-08T19:32:40.497" ContentLicense="CC BY-SA 3.0" />
  <row Id="25959" PostTypeId="2" ParentId="25735" CreationDate="2016-03-08T19:20:19.317" Score="10" Body="&lt;p&gt;Precision Approaches (PA), as you mention, have specific performance requirements, one of which is how &quot;good&quot; the vertical position measurement must be during an approach. In the case of a PA, ground systems either directly measure the aircraft's vertical position on the glide path (Precision Approach Radar in the case of parallel approaches), or provide a means to follow a precise vertical glide slope via a gauge in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For Approaches with Vertical Guidance (APV), there is vertical guidance, but the aircraft's vertical position is measured &lt;em&gt;onboard&lt;/em&gt; the aircraft by either a GPS position source or a barometric sensor. Either of those sensors are subject to measurement errors:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Barometric Measurement Errors:&lt;/strong&gt; ICAO Annex 10 section 4.4.2.4 defines the error model that is used for barometric altitude reporting systems. The 95% bound of the worst case is +/-282ft.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Barometric Setting Errors:&lt;/strong&gt; Additional errors are introduced depending on what barometric MSL pressure is selected on the altimeter and how that compares to current (actual) atmospheric pressures.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;GPS Measurement Errors:&lt;/strong&gt; While GPS position sensors provide very good horizontal position, GPS &lt;em&gt;vertical&lt;/em&gt; position is generally poor. &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/faq/gps/&quot;&gt;According to the FAA&lt;/a&gt;, the 95% vertical error of GPS systems used in civilian contexts is on the order of 300ft and according to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-138B.pdf&quot;&gt;this&lt;/a&gt; Advisory Circular (section 5-7), geometric/GPS altitude does not meet requirements for use in air traffic control internationally.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Combining these errors with flight technical errors while flying the approach, the total error you can expect can add up quickly. Compare that to the fact that in the vertical guidance of an ILS improves the closer you get to the ground, you can quickly see why the alternatives of GPS or altimetry don't quite cut it...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;So specifically to your question&lt;/strong&gt;: For an approach to be a precision approach, you need precise vertical position measurements, which an SBAS cannot provide.&lt;/p&gt;&#xA;" OwnerUserId="13849" LastEditorUserId="13849" LastEditDate="2016-03-09T23:43:37.413" LastActivityDate="2016-03-09T23:43:37.413" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25960" PostTypeId="2" ParentId="25958" CreationDate="2016-03-08T19:25:21.933" Score="0" Body="&lt;p&gt;Regarding the first point, from &lt;a href=&quot;https://www.scribd.com/doc/105499684/102/Elevator-Offload-Function&quot; rel=&quot;nofollow&quot;&gt;Lufthansa Technical Training Manual for 777&lt;/a&gt;, page 30:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Elevator Offload Function&#xA;  Operates only in the AirCommands to Determine when the Elevator is not at the Neutral Position for more than two seconds minimum.Commands the Horizontal Stabilizer to move as a Function of Airspeed. The Movement of the Horizontal Stabilizer then causes the Elevator to move to the Neutral Position&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-03-08T19:42:05.220" LastActivityDate="2016-03-08T19:42:05.220" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25961" PostTypeId="2" ParentId="2952" CreationDate="2016-03-08T19:35:01.203" Score="7" Body="&lt;p&gt;To your question of &quot;how low&quot;: In the US, radar coverage is generally pretty good, but there is a distinct floor below which an aircraft cannot be picked up by a radar system. The figure below shows this radar floor in the US:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/cuh4h.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cuh4h.jpg&quot; alt=&quot;Lowest Altitude with Radar Coverage in US based on ETMS data&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The figure was taken from &lt;a href=&quot;https://dspace.mit.edu/bitstream/handle/1721.1/67188/758649007-MIT.pdf?sequence=2&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, page 73.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the introduction of ADS-B as a surveillance source, this will change quickly. Areas where radar coverage is poor can be improved by the installation of an ADS-B receiver, which is significantly cheaper than a radar installation (~25X cheaper).&lt;/p&gt;&#xA;" OwnerUserId="13849" LastActivityDate="2016-03-08T19:35:01.203" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25962" PostTypeId="1" CreationDate="2016-03-08T20:43:01.020" Score="0" ViewCount="193" Body="&lt;p&gt;I am designing an aircraft and it is my first that will use a combustion engine rather than electric, so I am curious, &lt;em&gt;if I had a single engine in the fuselage and gear shafts to the wings that drove propellers, how would I achieve different speeds on the propellers?&lt;/em&gt; The 'plane' itself is more similar to a VTOL so the different speeds are needed. I would be fine with a solution that used smaller electric motors in it's mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or maybe I'm approaching this in a terribly inefficient way and there's a much better method to what I'm trying to achieve, I just feel stuck after battling it for a few days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft itself will look similar to this: &#xA;&lt;a href=&quot;https://i.stack.imgur.com/cUwGG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cUwGG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13920" LastEditorUserId="1467" LastEditDate="2016-03-08T20:51:39.717" LastActivityDate="2016-03-08T20:58:04.590" Title="Can I have two speeds on one motor?" Tags="&lt;vtol&gt;" AnswerCount="1" CommentCount="11" ClosedDate="2016-03-08T21:37:58.797" ContentLicense="CC BY-SA 3.0" />
  <row Id="25963" PostTypeId="2" ParentId="25962" CreationDate="2016-03-08T20:58:04.590" Score="2" Body="&lt;p&gt;The short answer is you probably wouldn't do it this way: Designing a drive system which allows you to split the work force between two output shafts at an arbitrary ratio (effectively an &lt;a href=&quot;https://en.wikipedia.org/wiki/Differential_%28mechanical_device%29#Active_differentials&quot; rel=&quot;nofollow&quot;&gt;active differential&lt;/a&gt;) is pretty complex, and failure-prone. The failure of the differential would be &quot;problematic&quot; (both rotors stop), and the failure of a single drive link would likely be catastrophic (one rotor stops in the VTOL configuration you have an extreme wing-over from the imbalanced thrust).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The generally preferred design for this type of aircraft has two full engines mounted on the wings (for example &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow&quot;&gt;the V-22 Osprey&lt;/a&gt;).&lt;br&gt;&#xA;Similar results can be achieved by vectoring thrust from a jet engine (as in &lt;a href=&quot;https://en.wikipedia.org/wiki/Harrier_Jump_Jet&quot; rel=&quot;nofollow&quot;&gt;the Harrier &quot;Jump Jet&quot;&lt;/a&gt;), which can be done with a single engine.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-03-08T20:58:04.590" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25966" PostTypeId="2" ParentId="25946" CreationDate="2016-03-09T00:30:08.003" Score="7" Body="&lt;p&gt;The crew checks the pitots and static ports before the flight to ensure they are in good condition and not blocked by objects or insects. Pitot tube (pitot-static) can be obstructed in-flight. Static ports are less affected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Detecting&lt;/strong&gt; a blocked pitot or static port: This is &lt;strong&gt;not done&lt;/strong&gt;, but is possible (e.g. send some air from the back of the tube in a pitot, and see if it can exit the tube at a normal rate (which is dependent on several parameters).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Unblock&lt;/strong&gt; a blocked pitot: &lt;strong&gt;In some cases&lt;/strong&gt; yes:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Melt ice or snow by heating the tube in flight, but the tube may be frozen for a minute from time to time. Some pitots are not heated and must be deiced naturally, which will be longer (while cruising in -50°C air, friction prevents aircraft skin to be cold. Concorde skin was about 100°C, meaning air friction just increased its temperature by 150°C).&lt;/li&gt;&#xA;&lt;li&gt;Drain water using drain holes in the pitot.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Redundancy&lt;/strong&gt; for pitots: &lt;strong&gt;Yes&lt;/strong&gt;, two or three exist on most airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Alert&lt;/strong&gt; for blocked pitot: &lt;strong&gt;Not a direct alert&lt;/strong&gt;, since a blocked pitot is not detected, but air data processors compare the different pressure values received from the different pitots, and in case of significant difference alert the crew and disconnect the automated units relying on pitot pressure (like the autopilot).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A message is displayed to emphasize that airspeed is &lt;em&gt;unreliable&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Dangerous&lt;/strong&gt;? Yes because if the unreliability of airspeed is not taken into account by the pilot, then &lt;strong&gt;stress and inappropriate actions&lt;/strong&gt; can occur because the aircraft is apparently not reacting to attitude changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;noreferrer&quot;&gt;AF447&lt;/a&gt; disaster is sadly a perfect demonstration of the stress that can be generated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the crew detects correctly the situation, then there is nothing special to do, they just need to continue (manual control) at the same altitude and with the same aircraft attitude until the speed becomes reliable again.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-09T08:35:44.690" LastActivityDate="2016-03-09T08:35:44.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25967" PostTypeId="2" ParentId="25933" CreationDate="2016-03-09T04:16:19.157" Score="0" Body="&lt;p&gt;Aircraft generate lift by increasing airspeed, while wind harvesters generate power by decreasing airspeed, so they'd be competing with each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming that there was a way to avoid that problem, it'd also need to store this energy, and large capacity batteries are incompatible with an aircraft's requirements for both high specific energy and high specific power.&lt;/p&gt;&#xA;" OwnerUserId="13930" LastActivityDate="2016-03-09T04:16:19.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25969" PostTypeId="1" CreationDate="2016-03-09T06:07:52.687" Score="1" ViewCount="409" Body="&lt;p&gt;What is the thrust availability per engine in Lockheed C130H?&#xA;The engines are Allison T-56-A-15 (SHP=4100, SFC=0.5)&#xA;Propellers = NP2000 eight Bladed(Prop Efficiency if assumed to be 90% constant at all speeds)&#xA;SHP - Shaft Horse Power&lt;/p&gt;&#xA;" OwnerUserId="13931" LastEditorUserId="13931" LastEditDate="2016-03-14T09:54:48.950" LastActivityDate="2016-03-14T09:54:48.950" Title="How much thrust is available from the Allison T-56-A-15 engine?" Tags="&lt;engine&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25970" PostTypeId="1" CreationDate="2016-03-09T06:36:49.853" Score="10" ViewCount="987" Body="&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the development of T-X program, a major step has been the refining of the technical requirements, in particular this &quot;sustained G&quot; maneuver:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The sustained G maneuver shall be flown with a standard configuration (i.e., clean with no external stores), at or above 80% fuel weight (relative to&#xA;  maximum fuel capacity), steady state flight, and standard day conditions. The maneuver will begin in level flight (flight path angle no lower than zero&#xA;  and no higher than two degrees nose high), wings level (+/‐ 5 degrees of bank), at or above 15,000 feet pressure altitude, and at or below 0.9M. From&#xA;  this point, the pilot shall immediately initiate bank and back pressure to achieve the sustained G. The sustained G must be maintained for a minimum&#xA;  of 140 continuous degrees. The pilot may begin reducing the load factor and rolling out after a minimum of 140 degrees in order to roll out at&#xA;  approximately 180 degrees of turn. The sustained G Threshold:  ≥ 6.5Gs; The sustained G ≥ 7.5Gs. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;seems to be quite challenging for &lt;a href=&quot;https://www.flightglobal.com/news/articles/usaf-reaffirms-ambitious-t-x-sustained-g-requirement-414531/&quot; rel=&quot;nofollow noreferrer&quot;&gt;the T-100 from Alenia and the BAe Hawk&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.flightglobal.com/news/articles/scorpion-will-not-be-proposed-for-usaf-t-x-competiti-417108/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alenia T-100&lt;/a&gt; is still bidding after changing partner.&lt;/li&gt;&#xA;&lt;li&gt;BAe, which partnered with Northrop Grumman, discarded the Hawk in favour of a &lt;a href=&quot;https://www.flightglobal.com/news/articles/northrop-grumman-offers-sneak-peek-of-full-t-x-conce-420004/&quot; rel=&quot;nofollow noreferrer&quot;&gt;clean sheet design&lt;/a&gt;. &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.flightglobal.com/news/articles/boeing-phantom-works-keeping-t-x-and-f-x-plans-under-420044/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing/Saab&lt;/a&gt; participate with a clean sheet design. &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.flightglobal.com/news/articles/lockheed-proposes-kai-t-50a-for-t-x-over-skunk-works-421837/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed&lt;/a&gt; proposing the T-50 after discarding a SkunkWork clean sheet design.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.flightglobal.com/news/articles/raytheon-offers-american-made-t-100-for-t-x-422269/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Textron Scorpion&lt;/a&gt; seems to have pulled out after the new set of requirements. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Trend&lt;/strong&gt;&#xA;The new requirement seemed to challenge the existing design. The Hawk could be considered &quot;old&quot; (first flight in 1974), the scorpion could be considered &quot;simple&quot;. The T-100 and the T-50 starting development mid 90s together with international partners (Italy/Russia,USA/Korea) should though be &quot;modern&quot; trainer. While the T-100 seems to be more challenged, Lockheed considered a clean sheet design as well, so was probably not too relaxed about the T-50 performance .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;&#xA; - Why is this request for maneuverability so important for the next generation of fighters?&#xA; - Should not be other factors like battle-space management more important?&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="22726" LastEditDate="2019-09-21T01:23:01.977" LastActivityDate="2019-09-21T01:23:01.977" Title="Why are high-g requirements so important for training next generation of fighter pilots?" Tags="&lt;military&gt;&lt;maneuverability&gt;&lt;trainer&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="25971" PostTypeId="1" CreationDate="2016-03-09T08:35:04.303" Score="4" ViewCount="1266" Body="&lt;p&gt;Usually max power is time limited for jet/piston engines to 10 or 5 minutes. Can anybody explain the reason? What will happen if those limits are exceeded?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="5517" LastEditDate="2016-03-09T14:24:05.873" LastActivityDate="2017-07-11T04:29:00.423" Title="Why is max power time limited for jet/piston engines?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;piston-engine&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25972" PostTypeId="1" AcceptedAnswerId="25973" CreationDate="2016-03-09T13:11:58.720" Score="25" ViewCount="3929" Body="&lt;p&gt;Looking around aviation news and history, I see that many commercial aircraft are touted to have this or that much time fly between New York and London. What caused the route between these two cities to be used in measuring the &quot;speed&quot; of the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-10T14:02:31.257" Title="Why is New York-London used in time measurement for aircraft?" Tags="&lt;aviation-history&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25973" PostTypeId="2" ParentId="25972" CreationDate="2016-03-09T13:47:09.957" Score="40" Body="&lt;p&gt;They are (and historically, were even more so) two of the biggest cities in the business world (ranked &lt;a href=&quot;https://en.wikipedia.org/wiki/Global_city&quot;&gt;Alpha++&lt;/a&gt;). That specific route has some of the highest rates of business travel and is, therefore, a fairly prestigious, famous route which is popular with fairly wealthy, prestigious people.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are also two of the most famous cities in the world, and most people know roughly where they are on a map. The fact they're separated by an ocean which is large but was just small enough to be possible to cross safely in the early days of aviation also helped, because it gives the impression of being further than it is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example it's a comparable distance to London-Dubai, but that doesn't &quot;feel&quot; as big due to being overland through Europe. Equally while many people know roughly where Dubai is nowadays, it wasn't anywhere near as famous 30-80 years ago.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="595" LastEditDate="2016-03-10T12:14:16.187" LastActivityDate="2016-03-10T12:14:16.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25974" PostTypeId="2" ParentId="25971" CreationDate="2016-03-09T14:43:54.723" Score="7" Body="&lt;p&gt;Maybe Nothing.... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe Catastrophic Failure...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any number published by an engine maker (or any aviation part maker for that matter) is the numbers they have tested it to. Thus if Continental or GE claims a 2000 hour TBO but puts a 5 minute limit on max power, that in turn means that the 2000TBO number is based on operations within these published limitations. Exceeding these limitations may cause TBO to arrive sooner than expected and could possibly cause undesired operating characteristics. It is of course possible that if you drive the engine at max power for a time greater than suggested, it will throw itself to pieces. However, this is unlikely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases there are physical limits based on the materials used in the engine. If exceeding maximum run time provides a way to generate internal temperatures that exceed the limits of an internal part you could very well have an issue very quickly. From my experience with piston engines it's generally a wear and heat fatigue issue when flogging the engine at max power. That being said if the POH calls for a maximum of 5 minutes at full power and you spend 5 minutes and 30 seconds at full power on a climb out chances are you will be fine. If you do this routinely you may find that your engine hits TBO long before the published numbers.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.flyingmag.com/rating-turboprops-power&quot; rel=&quot;nofollow noreferrer&quot;&gt;This article&lt;/a&gt; also alludes to the fact that there may be other limiting factors such as the strength of the gear box the engine is connected to. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The shp of a turboprop engine is restricted by the strength of the gearbox that drives the propeller, and by the ability of the airplane to handle the thrust developed by the prop.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On any note I would think that most manufacturers publish numbers that are on the conservative side for many reasons.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this question is highly related to TBO number you should check out &lt;a href=&quot;http://www.avweb.com/news/savvyaviator/187037-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article about some common myths&lt;/a&gt; around engine overhauling numbers and engine wear in general.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Definitions: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;TBO: &lt;a href=&quot;https://en.wikipedia.org/wiki/Time_between_overhaul&quot; rel=&quot;nofollow noreferrer&quot;&gt;Time Between Overhaul&lt;/a&gt;. This is generally the lifetime of an engine. Although some people commonly think this is a legal number it is only manufacturer suggestion and you are free to exceed it (and plenty of people do). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;POH: Pilots Operating Handbook. The document that outlines the limits and safe operation of a given airframe. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="23079" LastEditDate="2017-07-10T19:53:50.703" LastActivityDate="2017-07-10T19:53:50.703" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25975" PostTypeId="1" CreationDate="2016-03-09T14:56:44.377" Score="2" ViewCount="3892" Body="&lt;p&gt;Pilots training to become instrument rated must learn to intercept and track VOR and LOC courses. What are the basic rules of thumb all pilots should learn regarding picking a course for intercept and making corrections to maintain the course? How do they vary between VOR and LOC courses?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2016-08-09T06:58:27.623" Title="What are the rules of thumb for intercepting and tracking VOR and LOC courses?" Tags="&lt;instrument-procedures&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25976" PostTypeId="1" CreationDate="2016-03-09T15:23:15.063" Score="8" ViewCount="272" Body="&lt;p&gt;Are there ILS approaches where the LOC/non-precision procedure isn't authorized?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2019-03-25T21:37:44.877" Title="Are there ILS approaches where a non-precision procedure isn't allowed?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25977" PostTypeId="1" CreationDate="2016-03-09T15:26:00.047" Score="2" ViewCount="411" Body="&lt;p&gt;Are there ILS approaches out there where descending by the glide slope on a segment of the approach that's outside the final approach segment would cause the aircraft to descend below the no lower than altitude for the segment?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's why I'm asking. It's not uncommon for pilots to intercept the glide slope before the published glide slope intercept point and then to track it all the way down. If doing this could be dangerous or might not provide the protections ILS approach are designed to provide, it might be a better procedure to descend using step downs to the no lower than altitude for each segment only intercepting the glide slope at the published point for all approaches.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="8490" LastEditDate="2016-03-09T15:46:36.643" LastActivityDate="2016-03-09T18:09:28.320" Title="Are there ILS approaches where descending by the glide slope outside final might be dangerous?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="25980" PostTypeId="2" ParentId="25976" CreationDate="2016-03-09T16:23:54.917" Score="4" Body="&lt;p&gt;Yes, there are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;em&gt;Note: This is as opposed to those ILS approaches listed as &lt;code&gt;ILS or LOC&lt;/code&gt; in the title—such as &lt;code&gt;KGEG ILS or LOC RWY 3&lt;/code&gt;—which do have an authorized LOC approach.&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/8400.13.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Special Authorization Cat I ILS&lt;/a&gt;, and Cat II &amp;amp; III ILS approaches do not have authorized LOC procedures. These are precision only approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://skyvector.com/airport/GEG/Spokane-International-Airport&quot; rel=&quot;nofollow noreferrer&quot;&gt;KGEG&lt;/a&gt; approaches, for example. Specifically, the &lt;code&gt;ILS RWY 3 (SA CAT I)&lt;/code&gt;, and the &lt;code&gt;ILS RWY 3 (CAT II &amp;amp; III)&lt;/code&gt; approaches do not have authorized LOC procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this screen cap of the KGEG &lt;code&gt;ILS RWY 21 (SA CAT I)&lt;/code&gt; approach:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;[&lt;img src=&quot;https://i.stack.imgur.com/iO9lh.png&quot; alt=&quot;enter image description here&quot;&gt;][6]&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2019-03-25T20:29:07.840" LastActivityDate="2019-03-25T20:29:07.840" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="25981" PostTypeId="2" ParentId="25977" CreationDate="2016-03-09T18:09:28.320" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there ILS approaches out there where descending by the glide slope on a segment of the approach that's outside the final approach segment would cause the aircraft to descend below the no lower than altitude for the segment?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes.  See &lt;a href=&quot;http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2011/InFO11009.pdf&quot; rel=&quot;noreferrer&quot;&gt;InFO 11009&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In part the InFO reads:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On ILS approaches, stepdown fixes are established for obstacle or traffic separation.  For all practical purposes, the glide slope remains stationary regardless of atmospheric temperature and pressure.  Conversely, stepdown fixes are published for a pilot to fly using indicated altitude, which varies with temperature and pressure changes.  Therefore, the proximity of stepdown fixes in reference to the glide slope, changes with the weather.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;We know the old adage:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;From high (hot) to low (cold) look out below.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What isn't obvious about that adage is the perspective of that statement.  It is from the perspective of the pilot to the ground.  A glide slope's perspective, if you will, is from the ground to the pilot.  Thus what you will experience is this.  In &lt;strong&gt;warm weather&lt;/strong&gt;, the stepdown altitudes will be higher than the glideslope and you will need to level off to remain above the MEA until crossing the next stepdown fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You must remain above the MEA at all times till crossing the precision final approach fix.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-03-09T18:09:28.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25982" PostTypeId="2" ParentId="25971" CreationDate="2016-03-09T19:14:27.667" Score="4" Body="&lt;p&gt;I suspect that the answer might vary from aircraft to aircraft and engine to engine, so I'll answer specifically for an aircraft/engine combination I am familiar with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Lycoming O-360, of various models, was chosen by Robinson to power the R22 series.  This engine is widely used in fixed wing and rotaries, is more or less bullet proof when cared for properly and is serviced by a market with a good spares supply and availability of skilled mechanics and overhaul centres.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the R22 Beta II, the engine is capable of producing 180 HP but Robinson said  we only need 130 HP, maybe 140 HP at most but can you make it lighter?  I forget the numbers - they came from an interview with  Frank Robinson, I'm sure Google will lead you to accurate ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lycoming responded by making several changes without changing the major replaceable components including thinning the cylinder walls and making the cooling fins somewhat smaller.  This means that the engine is less capable of dispersing heat and consequently, cannot run at maximum power for long.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Eventually, they certified it at 145 HP (less than the maximum - i.e. &quot;derated&quot;).  The POH (Pilots Operating Handbook) allows using the maximum derated power, 145 HP, for short periods, from memory, 5 minutes.  The engine life and reliability are only good if these limits are not exceeded.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also limits on how much power the drive train, including the gearbox, tail rotor drive shaft and tail rotor gearbox, can handle which place limits on the maximum power the engine can safely produce.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In an emergency, it is possible at sea level to exceed the 145 derated maximum since there is no physical device to stop you putting the collective into your armpit or opening the throttle wide but there is a good chance that doing so will damage the drive train or blades and if exceeded, a maintenance inspection is mandatory.  Using the whole 180 HP will lead to damage and has been implicated in accidents.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-03-09T21:38:05.903" LastActivityDate="2016-03-09T21:38:05.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25983" PostTypeId="2" ParentId="25969" CreationDate="2016-03-09T19:46:13.220" Score="2" Body="&lt;p&gt;From Raymer's &quot;Conceptual Aircraft Design&quot;, page 327, equation 13.15:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ \eta_p = \frac{TV}{P}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$\eta_P$ is the propeller efficiency&lt;/li&gt;&#xA;&lt;li&gt;$T$ is the Thrust [kN]&lt;/li&gt;&#xA;&lt;li&gt;$V$ is the True Airspeed [m/s]&lt;/li&gt;&#xA;&lt;li&gt;$P$ is the engine power [kW]&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Reverting the formula you get that the Thrust per engine is given by:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$ T  = \frac{P \eta_p}{V}$$&lt;/p&gt;&#xA;" OwnerUserId="13754" LastActivityDate="2016-03-09T19:46:13.220" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25984" PostTypeId="2" ParentId="25975" CreationDate="2016-03-09T20:14:59.127" Score="2" Body="&lt;p&gt;the rule of thumb for IFR flying, including intercepting VOR and LOC courses, is the 5Ts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Throttle: turn the throttle to initiate a climb or descent &lt;/li&gt;&#xA;&lt;li&gt;Turn: to the new inbound or outbound heading &lt;/li&gt;&#xA;&lt;li&gt;Time: reset the timer to time the&#xA;new leg &lt;/li&gt;&#xA;&lt;li&gt;Twist: the OBS to the new course you're intercepting  &lt;/li&gt;&#xA;&lt;li&gt;Talk:&#xA;if you are at a reporting point, you should now use the radio&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-03-09T20:14:59.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25985" PostTypeId="1" AcceptedAnswerId="25986" CreationDate="2016-03-09T21:25:49.963" Score="2" ViewCount="654" Body="&lt;p&gt;What happened to the airframe of Aloha Airlines Flight 243, after the explosive decompression? &#xA;I know that the structures were studied for a while after the aircraft safely landed in  Kahului Airport, but what happened after that? &lt;/p&gt;&#xA;" OwnerUserId="13941" LastEditorUserId="13754" LastEditDate="2016-03-09T21:59:37.770" LastActivityDate="2016-03-09T21:59:37.770" Title="What happend to the airframe of the Aloha Airlines Flight 243?" Tags="&lt;boeing-737&gt;&lt;accident-investigation&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="25986" PostTypeId="2" ParentId="25985" CreationDate="2016-03-09T21:33:18.853" Score="5" Body="&lt;p&gt;&lt;a href=&quot;https://m.planespotters.net/airframe/Boeing/737/20209/N73711-Aloha-Airlines&quot; rel=&quot;noreferrer&quot;&gt;According to Planespotters&lt;/a&gt;, it appears that the airframe in question was destroyed in August 1988.&lt;/p&gt;&#xA;" OwnerUserId="1024" LastActivityDate="2016-03-09T21:33:18.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25987" PostTypeId="1" AcceptedAnswerId="25997" CreationDate="2016-03-10T00:23:46.540" Score="10" ViewCount="501" Body="&lt;p&gt;I have always assumed that landing separation depends on wake turbulence limits depending on weight class.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However I see that no minimum separation needed for the A380 as trailing aircraft (and in a few other cases):&#xA;&lt;a href=&quot;http://www.ais.gov.hk/HK_AIP/aic/AIC22-12.pdf&quot;&gt;http://www.ais.gov.hk/HK_AIP/aic/AIC22-12.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, what distance or time separations used in these cases, where wake turbulence isn't the limiting factor?&lt;/p&gt;&#xA;" OwnerUserId="843" LastEditorUserId="843" LastEditDate="2016-03-10T08:35:43.187" LastActivityDate="2016-03-10T10:36:04.100" Title="What is the minimum separation between two landing A380s?" Tags="&lt;airbus-a380&gt;&lt;wake-turbulence&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25988" PostTypeId="1" AcceptedAnswerId="25989" CreationDate="2016-03-10T00:41:20.937" Score="4" ViewCount="708" Body="&lt;p&gt;I was wondering what this little stick on the wing was. My best guesses are an antenna or some sort of air speed measuring tube?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UL7Zg.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UL7Zg.jpg&quot; alt=&quot;Yak-9&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kDNei.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kDNei.jpg&quot; alt=&quot;Yak-3&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13942" LastEditorUserId="12220" LastEditDate="2016-03-10T01:12:34.867" LastActivityDate="2016-03-10T01:12:34.867" Title="What is this thing sticking out in front of wings?" Tags="&lt;wing&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25989" PostTypeId="2" ParentId="25988" CreationDate="2016-03-10T00:46:35.250" Score="6" Body="&lt;p&gt;You're correct. That is the pitot tube (head), placed  there so that it is in undisturbed airflow. This location of pitot tube is found in othe aircraft too, like the Messerschmitt  Bf 109 G-2  as shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xExK9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xExK9.jpg&quot; alt=&quot;Pitot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Unknown&lt;a href=&quot;//www.wikidata.org/wiki/Q4233718&quot; rel=&quot;nofollow noreferrer&quot; title=&quot;wikidata:Q4233718&quot;&gt;&lt;/a&gt; - &lt;a href=&quot;http://www.militaryimages.net/photopost/showphoto.php/photo/8212&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.militaryimages.net/photopost/showphoto.php/photo/8212&lt;/a&gt;., Public Domain, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=2278317&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=2278317&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-03-10T00:52:08.703" LastActivityDate="2016-03-10T00:52:08.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25990" PostTypeId="1" AcceptedAnswerId="25991" CreationDate="2016-03-10T01:22:14.407" Score="12" ViewCount="1611" Body="&lt;p&gt;There's a little hole on the leading edge of the vertical stabilizer of this plane:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t7HK1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t7HK1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is that? What is its purpose?&lt;br&gt;&#xA;Thanks&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://www.airliners.net/photo/Delta-Air-Lines/McDonnell-Douglas-MD-88/1611318/&amp;amp;sid=9df8bdad06e6b8d0858b3d2eaa8e177b&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="14897" LastEditDate="2017-03-13T18:59:57.403" LastActivityDate="2017-06-05T16:28:52.877" Title="What is this hole on the tail of an MD-88?" Tags="&lt;aircraft-design&gt;&lt;equipment&gt;&lt;md-80&gt;&lt;dc-9-family&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25991" PostTypeId="2" ParentId="25990" CreationDate="2016-03-10T01:27:57.390" Score="16" Body="&lt;p&gt;That is the ram air intake for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_cycle_machine&quot; rel=&quot;nofollow noreferrer&quot;&gt;air conditioning packs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HBHXw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HBHXw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="2341" LastEditDate="2017-06-05T16:28:52.877" LastActivityDate="2017-06-05T16:28:52.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25992" PostTypeId="1" CreationDate="2016-03-10T02:01:28.540" Score="3" ViewCount="733" Body="&lt;p&gt;Looking at this photo I can see lots of lights on the fuselage of this MD81. It can't be a reflection, can it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BvKBC.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BvKBC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Aerolineas-Argentinas-%28Austral/McDonnell-Douglas-MD-81/0390855/&amp;amp;sid=8e991c7a68f8c7259f16b188192a6060&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are there so many lights? &lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="1467" LastEditDate="2019-11-14T09:15:11.730" LastActivityDate="2019-11-14T09:15:11.730" Title="MD81: Why are there so many lights on the fuselage?" Tags="&lt;aircraft-design&gt;&lt;fuselage&gt;&lt;dc-9-family&gt;&lt;aircraft-external-lights&gt;&lt;md-80&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="25993" PostTypeId="2" ParentId="25992" CreationDate="2016-03-10T03:01:51.517" Score="4" Body="&lt;p&gt;I'd say they're reflections. You can see the reflection of a building or something like it on the fuselage, and if you look close enough, you can see the poles of the 2 first lights.&#xA;Also most of them are at or near the windows' corners. There aren't any housings or mounts to lights on those spots.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="8321" LastEditDate="2016-03-10T10:05:53.700" LastActivityDate="2016-03-10T10:05:53.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="25994" PostTypeId="1" CreationDate="2016-03-10T05:46:07.233" Score="3" ViewCount="905" Body="&lt;p&gt;Where can I get weather information (preferably something similar to what pilots get) for a non-pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I usually use flightradar24 for flight tracking, would love to see weather data as well.&lt;/p&gt;&#xA;" OwnerUserId="13944" LastEditorUserId="12220" LastEditDate="2016-03-10T13:26:39.440" LastActivityDate="2019-02-22T20:03:59.220" Title="Where can I get aviation weather information?" Tags="&lt;weather&gt;&lt;website&gt;" AnswerCount="4" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="25996" PostTypeId="2" ParentId="25972" CreationDate="2016-03-10T07:34:24.243" Score="2" Body="&lt;p&gt;I suggest that the particular international air route is used because (1) both countries speak English and (2) English speakers read easily left to right. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that commercial aircraft pilots and air traffic controllers around the world speak English at least as a second language. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The particular route is typically perceived to be longer than many other routes that are the same length yet nearer the equator. Perceptions can be misleading. For instance, on a Mercator projection map, Greenland appears about  the same size as Africa, but actually Africa is 14 times the size of Greenland. &lt;/p&gt;&#xA;" OwnerUserId="13946" LastActivityDate="2016-03-10T07:34:24.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25997" PostTypeId="2" ParentId="25987" CreationDate="2016-03-10T08:04:54.977" Score="10" Body="&lt;p&gt;In general, the heavier an aircraft is, the greater the wake it produces but, it is also less affected by the wake of other aircraft.  In particular, an aircraft can always resist the wake turbulence of a lighter category aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/522.pdf&quot;&gt;It was found&lt;/a&gt; that the A380 was not affected by wake turbulence from any aircraft in front, including another A380, down to the minimum RADAR separation used on approaches which is 3NM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The RADAR separation used on any particular approach might be greater, but not less than this minimum therefore, there is no need to apply wake turbulence separation to a following A380 and the required RADAR separation for the approach is applied.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-03-10T10:36:04.100" LastActivityDate="2016-03-10T10:36:04.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="25998" PostTypeId="1" AcceptedAnswerId="26001" CreationDate="2016-03-10T08:47:44.017" Score="13" ViewCount="1341" Body="&lt;p&gt;Suppose a plane has a cruise speed of 400 knots  TAS. In a 4000 nm route we would have a round trip of 20 hours. If there was a jet stream of 100 knots in either direction, we would have 4000/500=8 hours in the tailwind direction and 4000/300=13.3 flying into the jet stream for a total of 21.3 hours. Now clearly, airlines are smarter than this and plan flightpaths, altitudes and speeds that maximize tailwinds and minimize time spent flying against the wind. The question, is to what extent does this strategy help? Does it simply offset the time lost compared to flying at the same speed in both directions? Or does it help even more than that. In other words, would a hypothetical windless world hurt the airline industry?&lt;/p&gt;&#xA;" OwnerDisplayName="user13363" LastActivityDate="2016-03-11T01:19:50.160" Title="Are jet streams a net benefit in time and fuel savings?" Tags="&lt;wind&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="25999" PostTypeId="2" ParentId="25992" CreationDate="2016-03-10T09:15:16.827" Score="6" Body="&lt;p&gt;I think they are reflection from some light posts in the background environment (green line above the blue &quot;horizon&quot; light), and the reflection of the wingtip position light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c8BTf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c8BTf.jpg&quot; alt=&quot;Reflection Comments&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastActivityDate="2016-03-10T09:15:16.827" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26000" PostTypeId="2" ParentId="25998" CreationDate="2016-03-10T09:23:06.467" Score="-1" Body="&lt;p&gt;The strategy helps in term of block fuel.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Case tailwind&lt;/strong&gt;: at the same True Air Speed (TAS),you fly faster in respect to the ground, Ground Speed GS.  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Case headwind&lt;/strong&gt;: to keep the same TAS now your GS will be slower.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Let's compute the impact of Ground Speed / True Airspeed on Fuel Consumption, from &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Getting_to_Grips_With_Aircraft_Performance.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus getting to grips with Aircraft performance&lt;/a&gt;, page 131:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The specific range (SR) is the distance covered per fuel unit.&#xA;  Basically speaking, the specific range is equal to:&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;$SR_{ground} = \frac{GS}{FF}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering Air Distance the specific range is equal to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$SR_{air} = \frac{TAS}{FF}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where FF is the fuel flow [Kg/h], and TAS/GS is given in [NM/h].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in a no-wind world, $TAS = GS$, otherwise at the same TAS constant, being the GS larger/smaller for a tail-/head- wind situation you will cover more/less distance with the same amount of fuel in respect to the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, operationally speaking, an aircraft tries to flies always at its most efficient speed, how speed effects the specific range can be seen in picture below (always from Aibus getting to grips with Aircraft Performance):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s9QpX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s9QpX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-03-10T10:52:26.933" LastActivityDate="2016-03-10T10:52:26.933" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26001" PostTypeId="2" ParentId="25998" CreationDate="2016-03-10T11:55:02.443" Score="12" Body="&lt;p&gt;Yes, Jetstreams are a net benefit on longer flights because it is easy to minimize headwinds and maximize tailwinds for both directions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Longer flights can detour hundreds of miles in order to take advantage of more favorable winds and still result in a net gain. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I frequently fly from Toronto to Hong Kong. We always fly a polar route YYZ-HKG as it is shorter, but usually take a HKG-YYZ North Pacific route over Alaska to take advantage of the prevailing winds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This daily flight is always scheduled at 15 hours 40 mins for Toronto to Hong Kong over the pole but only 14 hours 45 mins returning via a longer route over Alaska. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer flight routing over Alaska is a net benefit in time and fuel due to the prevailing westerly winds over the North Pacific.  This type of flexibility is not available on shorter flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;YYZ-HKG 6,787nm non-Stop 15:40&lt;/p&gt;&#xA;&#xA;&lt;p&gt;HKG-ANC-YYZ 7,050nm non-Stop 14:45&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/y66nb.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/y66nb.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-11T01:19:50.160" LastActivityDate="2016-03-11T01:19:50.160" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26002" PostTypeId="2" ParentId="1210" CreationDate="2016-03-10T12:50:40.770" Score="1" Body="&lt;p&gt;ICAO was explained. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;CAA is rather common name for aviation authorities in the country. Like police for law enforcement. But different countries call the same differently. Like in Russia they have name milicija for police &#xA;Here is a complete list of CAAs: &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_civil_aviation_authorities&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/List_of_civil_aviation_authorities&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA is mega scale CAA for americans.&#xA;EASA is mega scale CAA for European union.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small countries usually follow FAA or EASA or other big authority.&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-03-10T12:50:40.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26003" PostTypeId="2" ParentId="25994" CreationDate="2016-03-10T13:02:00.083" Score="3" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administration&quot; rel=&quot;nofollow&quot;&gt;NOAA&lt;/a&gt; collects &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow&quot;&gt;METAR&lt;/a&gt;s (current weather) from all over the world and publishes them at &lt;a href=&quot;http://weather.noaa.gov/pub/data/observations/metar/stations/&quot; rel=&quot;nofollow&quot;&gt;http://weather.noaa.gov/pub/data/observations/metar/stations/&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also collect &lt;a href=&quot;https://en.wikipedia.org/wiki/Terminal_aerodrome_forecast&quot; rel=&quot;nofollow&quot;&gt;TAF&lt;/a&gt;s (forecasts) and publish them at &lt;a href=&quot;http://weather.noaa.gov/pub/data/forecasts/taf/stations/&quot; rel=&quot;nofollow&quot;&gt;http://weather.noaa.gov/pub/data/forecasts/taf/stations/&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These reports are what the information told to pilots by controllers or broadcast in &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_Terminal_Information_Service&quot; rel=&quot;nofollow&quot;&gt;ATIS&lt;/a&gt; is based on, written in shorthand format designed for efficient transmission over teletype. If you look around the directory structure, there are also decoded versions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above links are complete, but intended more for machine consumption, being plain text files. You'll find many other sources that look more like normal web pages if you google for some airport code and “METAR” or “TAF”, but different parts of the world will be available at different places. The above links are most comprehensive source.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-10T13:14:04.093" LastActivityDate="2016-03-10T13:14:04.093" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26004" PostTypeId="2" ParentId="25972" CreationDate="2016-03-10T13:28:11.153" Score="1" Body="&lt;p&gt;New York to London is a route which benefits from a strong tail wind - it takes 6 hours (British Airways, in a 777) in that direction, but 8 hours from London to New York.&lt;/p&gt;&#xA;" OwnerUserId="13953" LastActivityDate="2016-03-10T13:28:11.153" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26005" PostTypeId="1" CreationDate="2016-03-10T13:44:38.437" Score="13" ViewCount="5752" Body="&lt;p&gt;Would not it be useful to have the angle of attack information displayed on the flight display? I know that we have shakers that alert pilot when the critical AOA is exceeded, but still we have cases of pilots stalling the aircraft (sometimes stalling one wing more than other).&#xA;I am sure designers have considered this but not chose to display AOA. I am curious what the reason could be.&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="5517" LastEditDate="2016-03-10T16:03:44.037" LastActivityDate="2019-04-21T13:26:49.330" Title="Why is angle of attack information not displayed in the cockpit?" Tags="&lt;angle-of-attack&gt;&lt;display&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26006" PostTypeId="1" AcceptedAnswerId="26011" CreationDate="2016-03-10T13:52:21.210" Score="26" ViewCount="10792" Body="&lt;p&gt;I've been taught before that the word &quot;takeoff&quot; should only be used when reading back a clearance, and that when requesting a clearance pilots should advise &quot;ready&quot; or &quot;ready for departure.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the really critical point to the question. I've always believed that the word &quot;takeoff&quot; should only be used when &lt;strong&gt;reading back a clearance for such an action&lt;/strong&gt;. Not when &lt;strong&gt;requesting a clearance&lt;/strong&gt; for that action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also heard it taught that this is true only for IFR flights but it's okay to ask for a clearance with the word &quot;takeoff&quot; when VFR. I don't see why the difference between VFR or IFR flight would be a factor here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has the ICAO, FAA or any other controlling organization released any written guidance on radio communications that covers this procedure?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="487" LastEditDate="2016-03-10T19:10:52.943" LastActivityDate="2016-08-19T18:45:07.147" Title="When should a pilot use the word &quot;takeoff?&quot;" Tags="&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26007" PostTypeId="2" ParentId="26005" CreationDate="2016-03-10T13:58:16.613" Score="16" Body="&lt;p&gt;Many aircraft do include them, because it's very useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example a modern 737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fpljQ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fpljQ.png&quot; alt=&quot;737 AoA indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Garmin G1000 (one of the more common General Aviation glass cockpits):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/G5W5R.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G5W5R.png&quot; alt=&quot;Garmin G1000 AoA indication&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically the part that looks a bit like this&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6YzGA.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6YzGA.png&quot; alt=&quot;Physical Garmin AoA indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a more traditional analog/mechanical gauge:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/e2tWq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e2tWq.jpg&quot; alt=&quot;Analog AoA indicator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is that usually when someone stalls, it's because they've made a mistake - not because they can't see the AoA. Either they're disorientated, or they've made a mistake with airspeed or an obstacle and are exceeding the aircraft's performance envelope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, the lack of an AoA dial isn't the reason you stall.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="8730" LastEditDate="2016-03-11T02:01:02.750" LastActivityDate="2016-03-11T02:01:02.750" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="26008" PostTypeId="2" ParentId="26005" CreationDate="2016-03-10T13:59:56.937" Score="7" Body="&lt;p&gt;It strongly depends on the aircraft we're talking about.&#xA;As an example, this is the Head Up Display of an F/A-18 &quot;Hornet&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ShTNQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ShTNQ.jpg&quot; alt=&quot;F/A-18 Head Up Display&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The number near the α is the angle of attack (AoA or α) measured in degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume that only in certain conditions knowing the exact value of the AoA may turn out to be useful (when nearing the limits maybe...). Usually, exceeding the maximum AoA is a the result of a mistake, not the mistake itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly-By-Wire systems usually do not allow the pilots to exceed the max AoA (Airbuses' Alpha Floor for instance) during normal operations.&lt;/p&gt;&#xA;" OwnerUserId="9656" LastActivityDate="2016-03-10T13:59:56.937" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26009" PostTypeId="2" ParentId="25972" CreationDate="2016-03-10T14:02:31.257" Score="2" Body="&lt;p&gt;Once a benchmark is set up, it's usually preferable to add data to it and continue using it, than to create a new benchmark, because it permits a comparison between current and previous samples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So even if the two cities are not the most logical choices now, they were in the past.&lt;/p&gt;&#xA;" OwnerUserId="13954" LastActivityDate="2016-03-10T14:02:31.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26010" PostTypeId="1" AcceptedAnswerId="26019" CreationDate="2016-03-10T14:03:14.663" Score="15" ViewCount="7159" Body="&lt;p&gt;Female airline pilots have an area of medical concern that male pilots don't deal with: reproductive issues. If a female airline pilot operating at an air carrier in the United States of America under the Federal Aviation Administration (FAA) were to become pregnant, how would this affect her standing with a first class medical and in general with operations at most airlines?&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="64" LastEditDate="2016-03-10T22:31:32.053" LastActivityDate="2020-12-10T17:37:16.267" Title="How does pregnancy affect airline pilots operating under FAA regulations?" Tags="&lt;faa-regulations&gt;&lt;pilots&gt;&lt;medical&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26011" PostTypeId="2" ParentId="26006" CreationDate="2016-03-10T14:03:20.117" Score="41" Body="&lt;p&gt;The word &quot;Takeoff&quot; should only be used when clearing somebody for takeoff, acknowledging your takeoff clearance, or cancelling/acknowledging a cancelled takeoff clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Departure&quot; should be used in all other circumstances, and as far as I'm aware whoever told you you could use the word Takeoff for VFR was wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anybody saying the word &quot;takeoff&quot; intends for an aircraft to enter, accelerate along, and then leave a runway in the immediate future: never anything else. Anybody saying otherwise should be immediately directed to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot;&gt;Wikipedia article for the Tenerife 747 disaster&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="-1" LastEditDate="2016-03-10T15:10:45.677" LastActivityDate="2016-03-10T15:10:45.677" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26012" PostTypeId="2" ParentId="26010" CreationDate="2016-03-10T15:17:44.150" Score="2" Body="&lt;p&gt;This is not specific to aviation, and I don't know the rules for countries other than Germany.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was just starting to argue about radiation doses, but this turns out not to be an issue in most cases:&lt;br&gt;&#xA;An average pilot / FA receives a dose of about 2 mSv / year (worker in nuclear power plant: 1mSv/y). An embryo / fetus is not allowed to collect more than 1mSv during the entire pregancy. This would not happen if the much larger mother collects 2mSv in one year, but there are still special precaution requirements. For example, the received dose has to be measured weekly instead of monthly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But our law gives even more. For example, after the 3rd month, a pregnant woman is not allowed to work on any means of transport, which an aircraft definitely is. And in general, pregnant woman are not allowed to do a job where they have to lift / push / move weights over 5kg permanently or 10kg occasionally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this laws, pregnant women have to be grounded immediately, no matter what the airline says. &lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2016-03-10T16:03:55.987" LastActivityDate="2016-03-10T16:03:55.987" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26013" PostTypeId="2" ParentId="26010" CreationDate="2016-03-10T15:27:02.553" Score="5" Body="&lt;p&gt;Here is a &lt;a href=&quot;http://flighttraining.aopa.org/magazine/1999/December/199912_Features_Flying_For_Two.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;decent article from AOPA&lt;/a&gt; on the matter (covers the topic from an FAA/USA standpoint). Looks like legally they don't have to say anything and they can't legally be pulled&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The law is on their side, too. In the early 1990s, the U.S. Supreme Court ruled that unless a woman voluntarily disclosed her pregnancy to her employer, she couldn't be switched out of her job to one that carries less risk to her fetus. Essentially this means that a woman has the right to decide when to declare she is pregnant to her employer, and to stay in her position even if it may cause harm to the developing fetus.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;It also seems like the regulations vary from airline to airline,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Few airlines today ban first trimester flying (from the time of conception through the first 12 weeks of pregnancy). Most, along with the military, permit flying through the second trimester (24 to 28 weeks) during an uncomplicated pregnancy. A few companies have no written policy and handle their pilots' pregnancies and leave issues on a case-by-case basis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The article goes on to cover  most of the topics related to this pretty comprehensively and is worth a read.&lt;/p&gt;&#xA;&lt;p&gt;Of course there are some &lt;a href=&quot;http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/expert-answers/air-travel-during-pregnancy/faq-20058087&quot; rel=&quot;nofollow noreferrer&quot;&gt;general medical concerns&lt;/a&gt; that any mother should take into account.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2020-12-10T17:37:16.267" LastActivityDate="2020-12-10T17:37:16.267" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26014" PostTypeId="2" ParentId="26005" CreationDate="2016-03-10T15:29:52.693" Score="14" Body="&lt;p&gt;Slightly off-topic, but I recently came across the &quot;side string&quot; which gives a direct reading of AoA.  Every gilder pilot is familiar with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Yaw_string&quot; rel=&quot;nofollow noreferrer&quot;&gt;yaw string&lt;/a&gt;, but in two years of learning to fly gliders, I'd never heard anyone mention the side string.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3Zvkn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Zvkn.jpg&quot; alt=&quot;Side String&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, in the ultralight / open-cockpit world they use a single piece of yarn mounted on a stick, which acts as a combination yaw and side string.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rqCKe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rqCKe.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2791" LastActivityDate="2016-03-10T15:29:52.693" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26016" PostTypeId="2" ParentId="16800" CreationDate="2016-03-10T16:28:15.180" Score="0" Body="&lt;p&gt;In a fixed wing aircraft this is a common aerobatic maneuver called a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tailslide&quot; rel=&quot;nofollow&quot;&gt;tailslide&lt;/a&gt;.  Many airplanes can safely perform this maneuver, and if you google around, you can easily find video.&lt;/p&gt;&#xA;" OwnerUserId="4405" LastEditorUserId="12720" LastEditDate="2016-03-12T22:15:53.970" LastActivityDate="2016-03-12T22:15:53.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26017" PostTypeId="2" ParentId="26006" CreationDate="2016-03-10T16:37:07.267" Score="10" Body="&lt;p&gt;ICAO Doc. 4444 specifies standards for ATC communication. &quot;DEPARTURE&quot; is used for taxi-ing etc, and &quot;TAKE-OFF&quot; is used when actually taking off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Europe, this &lt;a href=&quot;https://easa.europa.eu/essi/egast/wp-content/uploads/2011/03/EGAST_Radiotelephony-guide-for-VFR-pilots.pdf&quot;&gt;EASA guide&lt;/a&gt; specifies much the same thing.&lt;/p&gt;&#xA;" OwnerUserId="6959" LastActivityDate="2016-03-10T16:37:07.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26018" PostTypeId="2" ParentId="25994" CreationDate="2016-03-10T17:00:39.687" Score="1" Body="&lt;p&gt;The &lt;a href=&quot;http://www.aviationweather.gov/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Digital Data Service (ADDS)&lt;/a&gt; is an excellent source for aviation weather information within the US. This website is free and completely open to non-pilots (as opposed to &lt;a href=&quot;https://www.lmfsweb.afss.com/Website/home&quot; rel=&quot;nofollow noreferrer&quot;&gt;1800wxbrief&lt;/a&gt;, for example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.aviationweather.gov/metar&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR page&lt;/a&gt; gives up to date weather observations for airports throughout the US. The other pages include many other useful weather products, including forecasts, pilot reports, and satellite or radar images.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, this is a website that I use frequently, and have used throughout my career. To a non-pilot some of the products may seem incomprehensible, but the website does provide &lt;a href=&quot;http://www.aviationweather.gov/help&quot; rel=&quot;nofollow noreferrer&quot;&gt;help pages&lt;/a&gt;. Perhaps most importantly for a non-pilot, many of the coded textual products are available in a decoded, normal language format.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-06-15T04:11:18.760" LastActivityDate="2017-06-15T04:11:18.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26019" PostTypeId="2" ParentId="26010" CreationDate="2016-03-10T17:02:13.873" Score="12" Body="&lt;p&gt;As long as the pilot is having a first class medical, her pregnancy should have no effect on the operations, at least legally, though the regulations differ from country to country.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I'm not aware of any FAA regulations that prohibit pilot ing during pregnancy. The closest it comes is in &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.53&quot; rel=&quot;noreferrer&quot;&gt;14 CFR § 61.53 - Prohibition on operations during medical deficiency&lt;/a&gt;, which says (noting that pregnancy is not a medical deficiency in any way and the regulation is taken here in the widest sense) that:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Operations that require a medical certificate. Except as provided for in paragraph (b) of this section, no person who holds a medical certificate issued under part 67 of this chapter may act as pilot in command, or in any other capacity as a required pilot flight crewmember, while that person:&lt;/p&gt;&#xA;&lt;p&gt;(1) Knows or has reason to know of any medical condition that would make the person unable to meet the requirements for the medical certificate necessary for the pilot operation&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As long as the pilot feels that she is medically fit and has a valid medical certificate, they can't be legally prevented from flying the aircraft.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;In case of other regulattions (like EASA), pregnant women are not allowed to pilot after 26 weeks of pregnance. For example, &lt;a href=&quot;https://www.caa.co.uk/Aeromedical-Examiners/Medical-standards/Pilots-%28EASA%29/Conditions/Obs-and-gynae/Obstetrics-and-gynaecology-guidance-material-GM/#Preg&quot; rel=&quot;noreferrer&quot;&gt;UK Aviation Authority&lt;/a&gt; says:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(c) Pregnancy&lt;/p&gt;&#xA;&lt;p&gt;(1) In the case of pregnancy, if the AeMC or AME considers that the licence holder is fit to exercise her privileges, he/she shall limit the validity period of the medical certificate to the end of the 26th week of gestation.  After this point, the certificate shall be suspended.  The suspension shall be lifted after full recovery following the end of the pregnancy.&lt;/p&gt;&#xA;&lt;p&gt;(2) Holders of class 1 medical certificates shall only exercise the privileges of their licences until the 26th week of gestation with an OML.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;There are a number of medical issues that the pilot should be aware of while pregnant, so that appropriate measures could be taken, like,&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Ability to move the controls to their full extent.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ability to wear seat belts.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Effect of high altitude operation on the foetus&lt;/p&gt;&#xA;&lt;p&gt;among others. The airline policy will vary and they have to consider a number of other conditions- for example, the ability of flight crew to egress during a crash etc.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-10T17:02:13.873" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26020" PostTypeId="2" ParentId="26006" CreationDate="2016-03-10T17:09:39.613" Score="0" Body="&lt;p&gt;The ICAO Common Taxonomy Team &lt;a href=&quot;http://www.intlaviationstandards.org/Documents/PhaseofFlightDefinitions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;defines take-off as&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;From the application of takeoff power, through rotation and to an altitude of 35 feet above runway elevation. This phase of flight includes the following subphases:&lt;/p&gt;&#xA;&lt;p&gt;• Takeoff.  From the application of takeoff power, through rotation and to an altitude of 35 feet above runway elevation or until gear-up selection, whichever comes first.&lt;/p&gt;&#xA;&lt;p&gt;• Rejected Takeoff.  During takeoff, from the point where the decision to abort has been taken until the aircraft begins to taxi from the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, the term 'takeoff' should be used only if the intention is to acclerate, rotate and leave the runway. Use of takeoff in any other sense would result in confusion, with potentially dangerous consequences.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-10T17:09:39.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26021" PostTypeId="1" AcceptedAnswerId="26024" CreationDate="2016-03-10T17:13:17.177" Score="11" ViewCount="2322" Body="&lt;p&gt;After years of scientific research on the performance of commercial aircraft like 777's or A320'S, the cabin noise is still very loud. Modern aircraft have new features like serrated engine nacelles, like on the 747-8 or 787 engines; improved aerodynamics; vortex generators; cabin insulation, etc. So why do aircraft still have so much cabin noise after all these improvements? &lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-10T17:22:27.850" LastActivityDate="2018-02-15T23:20:30.303" Title="Why are modern commercial airplanes still so noisy?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26023" PostTypeId="2" ParentId="25998" CreationDate="2016-03-10T17:35:04.177" Score="4" Body="&lt;p&gt;The answer I'm about to give is purely theoretical, and many other factors are specific to Jetstreams, including the ability of a plane to navigate around them. However this is an interesting mathematical result indicating that &lt;strong&gt;in general winds are net negatives&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's imagine a plane flying a round trip 1000km each way at TAS 200kmh. In still air the trip takes 5hrs each way for a &lt;strong&gt;total of 10hrs.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the same trip, with a 50kmh wind (headwind one way, tailwind the other), the tailwind leg takes 4hrs (1000/(200+50)). The headwind leg takes 6.66 hrs (1000/(200-50)). &lt;strong&gt;Total of 10.66hrs.&lt;/strong&gt; The wind has a net negative effect. In our simplified world more time means more fuel, so there would be a negative on fuel consumption too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simple explanation is that the plane spends more time on the headwind leg, and less on the tailwind leg. The advantage on the tailwind does not cancel out the disadvantage on the headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This answer has little bearing on actual reality, though it might apply to smaller aircraft without the ability to avoid winds. But it mainly illustrates a principle that may be useful in making rough time estimates of round trips.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2016-03-10T17:40:43.020" LastActivityDate="2016-03-10T17:40:43.020" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26024" PostTypeId="2" ParentId="26021" CreationDate="2016-03-10T17:41:27.563" Score="18" Body="&lt;p&gt;Like everything in aviation its a trade off of a few factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Efficiency&lt;/strong&gt;: A non-running engine is pretty quiet but that's of little use to a pilot who needs thrust to actually go anywhere. Now you can have lots of sound suppression in an engine and alter the airflow and what not but in the end of the day jets work on Newton's third law so you still need to throw a hot mass out the back. Any attempt to baffle this will take a toll on efficiency. (Side note, car exhausts have a similar effect on car engines these days). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Weight&lt;/strong&gt;: The generally accepted way to reduce noise is to insulate against it. What you are really doing is adding material to absorb the mechanical energy that is the sound wave and dissipate it. Generally this is &lt;a href=&quot;http://www.aircraftspruce.com/catalog/appages/soundproofinstall.php&quot;&gt;done with insulation&lt;/a&gt; of some kind (there is a variety of styles). But like anything this takes a toll on weight and will reduce what you can carry. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cost&lt;/strong&gt;: Insulation does wear out and break down over time (its usually some kind of foam), so the more you have the more you need to replace. Also of importance is the fact that most of it gets removed during check to inspect the airframe so having a lot of insulation will add to your down time during checks (this costs the airline money in terms of hours).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you take a look at some custom-built private planes you will see some of the things they can do in terms of added noise reduction and what those implementations look like. On the other hand &lt;a href=&quot;https://en.wikipedia.org/wiki/Active_noise_control&quot;&gt;active noise control&lt;/a&gt; is becoming a cheaper and more efficient technology in headphones which makes a case for not needing to improve insulation (it will eventually be cheaper to have a pair of ANR headphones for everyone than maintain a lot of insulation). A lot of the GA community has moved to ANR headsets which are much nicer than their traditional counterparts. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="946" LastEditDate="2016-03-10T21:42:50.893" LastActivityDate="2016-03-10T21:42:50.893" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26025" PostTypeId="2" ParentId="26005" CreationDate="2016-03-10T17:48:53.137" Score="2" Body="&lt;p&gt;As others have noted many aircraft do have AOA indicators. Military A/C tend to have them next to the HUD on the left side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage using AOA over stall speed is that the stall AOA is constant while the stall speed depends upon weight. Greater weights =&gt; lower stall speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This difference will be important when there are large differences in A/C weights. If your F-18 has 4x2000lb bombs the stall speed is much different depending upon whether those bombs are dropped or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With your average cessna, the weight change of the A/C/ does not change the stall speed significantly. An AOA indicator does not provide as much value relative to its cost and weight.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastEditorUserId="2129" LastEditDate="2019-04-21T13:26:49.330" LastActivityDate="2019-04-21T13:26:49.330" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26026" PostTypeId="2" ParentId="26006" CreationDate="2016-03-10T17:55:59.613" Score="8" Body="&lt;p&gt;There's no definitive FAA statement one way or another that I could find. Outside the US and per ICAO, &quot;take-off&quot; is only used when accepting a take-off clearance and you should use &quot;departure&quot; in other situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's nothing I could find about departure vs. take-off phraseology in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;P/CG&lt;/a&gt; or &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM&lt;/a&gt;. The &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC orders 4-3-1&lt;/a&gt; do mention it, in the context of clearances:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4−3−1. DEPARTURE TERMINOLOGY&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Avoid using the term “takeoff” except to actually clear an aircraft&#xA;  for takeoff or to cancel a takeoff clearance. Use such terms as&#xA;  “depart,” “departure,” or “fly” in clearances when necessary.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AIM uses &quot;departure&quot; in its examples but makes no comment about avoiding &quot;take-off&quot; and an FAA &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/publications/media/Runway_Safety_Best_Practices_Brochure.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;runway safety publication&lt;/a&gt; doesn't have anything to say about it either. AOPA &lt;a href=&quot;http://flighttraining.aopa.org/magazine/1999/January/199901_Features_ATC_Communications.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;has an article&lt;/a&gt; (from 1999, admittedly, so perhaps it's now considered outdated) that says that pilots &lt;em&gt;can&lt;/em&gt; use &quot;take-off&quot; to tell ATC they're ready:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When you're ready for takeoff, use the same &quot;who, where, and what&quot;&#xA;  format for your initial call to the tower - &quot;Anytown tower, Trainer&#xA;  zero-zero-zero-zero-Yankee , ready for takeoff Runway three-three.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That phraseology is commonly used at my local airport in the US but it would be a major no-no in South Africa, where I learned to fly. And Jon's &lt;a href=&quot;https://aviation.stackexchange.com/a/26011/62&quot;&gt;answer&lt;/a&gt; is based on UK experience (only because it's in his profile), so it looks like an ICAO vs. US thing, at least to some extent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And indeed, &lt;a href=&quot;http://www.navcanada.ca/EN/media/Publications/ICAO-Doc-4444-EN.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO document 4444&lt;/a&gt;  uses the word &quot;departure&quot; as part of &quot;preparation for take-off&quot;, and &quot;take-off&quot; itself for &quot;take-off clearances&quot; (see sections 12.2.4.10 and 12.3.4.11). 12.2.4.10 says that pilots only need to say &quot;ready&quot; to inform ATC that they're ready for departure: &quot;Tower, N12345 is holding at 18, ready&quot;. It doesn't address uncontrolled fields, but the usual call I was taught was &quot;N12345 is departing runway 18&quot;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-08-19T18:45:07.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26027" PostTypeId="1" AcceptedAnswerId="26028" CreationDate="2016-03-10T18:01:21.710" Score="1" ViewCount="371" Body="&lt;p&gt;61.65 says an instrument applicant must have 40 hours of actual or simulated instrument time, 15 of which must be from an authorized instructor. What about the remaining 25 hours? Someone without an instrument rating can't file and go fly an IFR flight, right?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-03-10T18:31:55.447" Title="An instrument applicant must have 40 hours of actual or simulated time. Can some of this be flown without an instructor?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-03-10T20:57:22.243" ContentLicense="CC BY-SA 3.0" />
  <row Id="26028" PostTypeId="2" ParentId="26027" CreationDate="2016-03-10T18:31:55.447" Score="4" Body="&lt;p&gt;The 25 hours that are not required to be &quot;instrument instruction&quot; may be flown under the hood with a safety pilot. This is the usual way to accumulate some of the simulated instrument time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe this time may also be flown &amp;amp; logged in actual IMC with an instrument rated pilot acting as PIC (their name on the flight plan, etc.) and the instrument student acting as sole manipulator of the controls, but you may prefer to conduct your actual IMC practice with an instructor.&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-03-10T18:31:55.447" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26030" PostTypeId="1" CreationDate="2016-03-10T19:55:02.347" Score="11" ViewCount="21313" Body="&lt;p&gt;Is there any way of telling on both a VFR and IFR chart what type of VOR we are looking at?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="62" LastEditDate="2016-03-10T20:06:37.273" LastActivityDate="2021-03-08T08:36:56.957" Title="How do you know if a VOR is High, Low, or Terminal?" Tags="&lt;aeronautical-charts&gt;&lt;navaids&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26031" PostTypeId="1" AcceptedAnswerId="26032" CreationDate="2016-03-10T20:11:29.110" Score="12" ViewCount="80691" Body="&lt;p&gt;What are the differences between an OBS, a CDI, a Heading indicator, and an HSI? As far as I can tell they all use VORs. Why would 4 different version of the same instrument be invented? Is the HSI the most advanced of the 4 because it shows the most detail? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oBARQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oBARQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6dhv3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6dhv3.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/28T12.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/28T12.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/77Gtg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/77Gtg.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="11402" LastEditDate="2016-03-10T20:16:53.343" LastActivityDate="2018-09-13T13:27:08.287" Title="What are the differences between an OBS, a CDI, a Heading indicator, and an HSI?" Tags="&lt;navigation&gt;&lt;flight-instruments&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26032" PostTypeId="2" ParentId="26031" CreationDate="2016-03-10T20:25:44.303" Score="18" Body="&lt;p&gt;Check out &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf&quot; rel=&quot;noreferrer&quot;&gt;this manual from the FAA on flight instruments&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Heading_indicator&quot; rel=&quot;noreferrer&quot;&gt;Heading Indicator&lt;/a&gt;: &lt;a href=&quot;https://i.stack.imgur.com/28T12s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/28T12s.jpg&quot; alt=&quot;Heading Indicator&quot; /&gt;&lt;/a&gt;&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The heading indicator is fundamentally a mechanical&#xA;instrument designed to facilitate the use of the magnetic&#xA;compass. Errors in the magnetic compass are numerous,&#xA;making straight flight and precision turns to headings difficult&#xA;to accomplish, particularly in turbulent air. A heading&#xA;indicator, however, is not affected by the forces that make&#xA;the magnetic compass difficult to interpret.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Heading Indicators are not VOR related. They simple provide an alternative to the compass and are generally used when the compass reading may be inaccurate (non straight and level flight). Due to their functionality they need to be periodically aligned with the compass.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Course_deviation_indicator&quot; rel=&quot;noreferrer&quot;&gt;Course Deviation Indicator&lt;/a&gt;: &lt;a href=&quot;https://i.stack.imgur.com/6dhv3s.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6dhv3s.jpg&quot; alt=&quot;CDI&quot; /&gt;&lt;/a&gt;&lt;/h1&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A course deviation indicator (CDI) is an avionics instrument used in aircraft navigation to determine an aircraft's lateral position in relation to a course. If the location of the aircraft is to the left of course, the needle deflects to the right, and vice versa.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The &lt;strong&gt;OBS&lt;/strong&gt; (Omni Bearing Selector) knob is on the CDI, it is not its own instrument. The knob allows the selection (via the outer ring) of the radial (course) you wish to track from a VOR ground station. When tracking a radial you only track left/right deviation and thus only a single needle is required (the first picture you have). For instrument flying you also need to track the glide slope for an approach and thus vertical deviation may also be displayed on a CDI. When on an instrument approach the CDI is used to track the left/right deviation from the runway (not a VOR).&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Horizontal_situation_indicator&quot; rel=&quot;noreferrer&quot;&gt;Horizontal Situation Indicator (HSI):&lt;/a&gt;  &lt;a href=&quot;https://i.stack.imgur.com/77Gtgs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/77Gtgs.jpg&quot; alt=&quot;HSI&quot; /&gt;&lt;/a&gt;&lt;/h1&gt;&#xA;&lt;p&gt;Is a CDI and Heading Indicator packed into one unit. it provides both left right deviation along with glide slope information as well as heading indication in turns. Many HSI's are coupled to auto pilots and may allow course selection via a heading knob if they are connected to do so. The HSI is not any more advanced than the sum of its counter parts but it is more complex and to a new pilot may be hard to read.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-10T22:27:19.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26033" PostTypeId="2" ParentId="26030" CreationDate="2016-03-10T21:52:28.680" Score="5" Body="&lt;p&gt;Typically terminal VOR's do not have compass roses around them if they are strictly terminal VOR's. I can't find an example of one so I don't have an image for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit&lt;/strong&gt; I found an example:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/TpPQ9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TpPQ9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.skyvector.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: SkyVector&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DEN VOR has no compass rose, so its either a terminal VOR or they omitted the compass rose for clarity. There are two other VOR's in close proximity, MILE HIGH on the North East side of the field and Falcon to the east of Buckley AFB. According to &lt;a href=&quot;http://www.airnav.com/cgi-bin/navaid-info?id=DEN&amp;amp;type=VOR.DME&amp;amp;name=DENVER&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirNav NavAid Info&lt;/a&gt; its a high VOR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as high/low VOR, one way to tell is to look at the High/Low enroute IFR charts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, here is a portion of a low-enroute IFR chart:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MFJP7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MFJP7.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.skyvector.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: SkyVector&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see two VOR stations on here labeled Minot Intl and Devils Lake Rgnl with a victor airway between them (V430).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the same area from the high enroute IFR chart:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KjdFR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KjdFR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.skyvector.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: SkyVector&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see that the VOR symbol around Devils Lake Rgnl has disappeared and (although its difficult to see) the VOR symbol has also disappeared. &lt;a href=&quot;http://www.airnav.com/cgi-bin/navaid-info?id=DVL&amp;amp;type=VOR.DME&quot; rel=&quot;nofollow noreferrer&quot;&gt;NavAid Website lists DVL (Devils Lake) as a LOW VOR&lt;/a&gt; and also lists &lt;a href=&quot;http://www.airnav.com/cgi-bin/navaid-info?id=MOT&amp;amp;type=VOR&quot; rel=&quot;nofollow noreferrer&quot;&gt;MOT (Minot International) as a HIGH VOR&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no differentiation between the VOR high/low symbols on a VFR chart because low altitude VOR's can serve aircraft up to 18,000 feet where you would need to file an IFR flight plan anyway, so all VOR's regardless of high/low are available to VFR flights. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Putting it another (technical) way is that high/low VOR's have the same service volume for VFR and low-enroute IFR flights, so they do not need to be distinguished on VFR or low-enroute IFR charts.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-11T14:16:45.470" LastActivityDate="2016-03-11T14:16:45.470" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26034" PostTypeId="1" CreationDate="2016-03-10T22:58:52.320" Score="0" ViewCount="481" Body="&lt;p&gt;I've always wanted to be a pilot from the age of 3. I've always dreamed about flying high in the sky above the clouds and getting that amazing experience that you can't get any other way. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm now turning 16 and am realising it is coming close for me to start my goal of becoming a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would appreciate if anyone could give me some advice on what to do to become a pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What qualifications you need?&#xA;Where you train?&#xA;Wages?&#xA;What are the health requirements?&#xA;Etc&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is for a pilot in the UK who is hoping to work in Dubai for Emirates. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks. &lt;/p&gt;&#xA;" OwnerUserId="13964" LastActivityDate="2016-03-11T05:24:51.827" Title="Advice for a future pilot?" Tags="&lt;pilots&gt;&lt;student-pilot&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2016-03-11T09:12:57.347" ContentLicense="CC BY-SA 3.0" />
  <row Id="26035" PostTypeId="2" ParentId="18940" CreationDate="2016-03-10T23:23:58.290" Score="-1" Body="&lt;p&gt;Airplanes have many sensors which are sensitive to electrical noise. And moving magnets can cause an electrical flow, hence electrical noise. As you can not estimate who is carrying how strong magnets it is safer to forbid them in life-critical environments like airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And about compass, it is only needed for an initial heading estimate, and it replaces GPS heading after moving a few meters in aircraft. So the compass is not a big deal as long as GPS is available.&lt;/p&gt;&#xA;" OwnerUserId="13965" LastEditorUserId="849" LastEditDate="2018-03-30T23:55:51.850" LastActivityDate="2018-03-30T23:55:51.850" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26036" PostTypeId="1" CreationDate="2016-03-10T23:31:28.387" Score="9" ViewCount="11137" Body="&lt;p&gt;The manual that came with my Jeppensen E6B has the following sample...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If an aircraft is flying at 12,500 feet with an outside air&#xA;  temperature of -20C and the altimeter is set on 30.42 inches of&#xA;  mercury, what is the true altitude?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The explanation goes on to find a pressure altitude of 12,000 feet.  After placing -20C over 12,000 we find 12,500 (12.5) on the B scale and read the true altitude of 12,000 (12.0) on the outer ring.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking closely at the outer ring, I see that the true altitude is actually just slightly below 12,000.  Now for practical purposes I realize we don't worry about differences like this and round the result.  But I'm working on a project in which I need to calculate the true altitude precisely.  I'm having a difficult time finding the formula.  The closest thing I have found says the correction is 4 feet per thousand feet indicated per degree off of ISA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I attempt to apply that formula to our sample problem I get 4 * 12.5 * -35 = -1750.   Applying that correction gives a value far below expected so obviously I'm doing something wrong.  Can someone straighten me out here?  References to documentation with educational value are especially welcome.&lt;/p&gt;&#xA;" OwnerUserId="688" LastEditorUserId="19" LastEditDate="2016-06-28T16:23:32.477" LastActivityDate="2019-09-22T18:17:09.413" Title="How can true altitude be calculated from pressure altitude, temperature and altimeter setting?" Tags="&lt;altitude&gt;&lt;altimeter&gt;&lt;performance-calculation&gt;&lt;e6b&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26037" PostTypeId="2" ParentId="26034" CreationDate="2016-03-11T00:20:35.177" Score="1" Body="&lt;p&gt;What you could do right now is train to be a glider pilot. You probably already have the right age. It is a wonderful experience, and it will be a good basis for a power license.&lt;/p&gt;&#xA;" OwnerUserId="690" LastActivityDate="2016-03-11T00:20:35.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26038" PostTypeId="2" ParentId="26006" CreationDate="2016-03-11T01:00:01.003" Score="2" Body="&lt;p&gt;&quot;Take-off&quot; indicates to others on frequency that a potentially high-risk operation is about to be undertaken by another aircraft, which they should take a special interest in for situational awareness and conflict management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Procedures vary by field, but standard ICAO phraseology (or equivalent for the jurisdiction) should be employed for all the radio telephony. Assuming the aircraft is waiting on a taxiway at the active runway, a typical notification to the tower that the crew are ready to depart might be:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Some Tower. Speedbird Niner Juliet. Holding runway 27 left, ready for departure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Typical responses from the tower would be:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Cleared for takeoff [runway], wind [...]&lt;/strong&gt;. The aircraft is cleared -- at the crew's discretion -- to taxi onto the designated runway, apply power and lift off.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Runway [identifier], line up and wait.&lt;/strong&gt; Cleared to taxi onto the designated runway, DO NOT commence take-off roll, await further instructions. (Delays typically for spacing / sequencing, conflicting traffic movements, departures taking place behind arriving aircraft, ...)&lt;/li&gt;&#xA;&lt;li&gt;No immediate action. The aircraft cannot enter the active runway for some reason, so continues to wait at the hold-short line until further instructions or clearances are provided.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;At some fields, it may not be necessary or desired to provide an indication of departure readiness. Ground may provide such indication on the pilot's behalf and advise at switchover to simply &lt;em&gt;monitor&lt;/em&gt; the tower frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Non-standard RT phraseology does often creep in. I sometimes hear either &quot;[Callsign] rolling&quot;, &quot;rolling [runway identifier]&quot; or a combination announced upon commencing the roll. This is particularly the case if there has been a delay between issuing the take-off clearance and the departure commencing. It's a courtesy and notification to others on the field or in the pattern to watch out for the metal about to be thrown along the tarmac at high-speed.&lt;/p&gt;&#xA;" OwnerUserId="2032" LastEditorUserId="2032" LastEditDate="2016-03-13T00:40:31.280" LastActivityDate="2016-03-13T00:40:31.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26039" PostTypeId="1" AcceptedAnswerId="26043" CreationDate="2016-03-11T02:43:30.960" Score="15" ViewCount="5895" Body="&lt;p&gt;Below the windows, ahead of the seat, there are small grilles. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/RRiSy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RRiSy.jpg&quot; alt=&quot;Boeing 787&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Boeing/Boeing-787-8-Dreamliner/2065806/L/&amp;amp;sid=a5aa987f4fa76aa5b2451cb0291aa568&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are those for?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="3386" LastEditDate="2017-07-06T21:18:58.397" LastActivityDate="2021-01-28T11:34:27.173" Title="What are these grilles in the passenger cabin of this 787?" Tags="&lt;aircraft-systems&gt;&lt;feature-identification&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26040" PostTypeId="2" ParentId="26034" CreationDate="2016-03-11T05:24:51.827" Score="1" Body="&lt;p&gt;Remember that the great majority of pilots don't get paid to fly, we pay to fly - for lessons, renting or buying a plane, fuel, etc.  There's a big difference between the effort, qualifications, and money needed to become a private pilot, and what's needed to become a comercial or airline pilot.  In the US, at least, anyone in reasonably good health can become a sport or private pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope I'm not offending anyone here when I say that being a commercial pilot is work, and making just about anything into an 8-5 job can take the edge off that amazing experience.  Or at least it seems that way to this private pilot :-)&lt;/p&gt;&#xA;" OwnerUserId="6968" LastActivityDate="2016-03-11T05:24:51.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26041" PostTypeId="2" ParentId="9676" CreationDate="2016-03-11T05:48:13.443" Score="0" Body="&lt;p&gt;It is ground power unit.&#xA;Due to the technical difficulty on ground to operate APU, which is the source of power for the aircraft.&#xA;Aircraft engineers connect GPU.&lt;/p&gt;&#xA;" OwnerUserId="13966" LastActivityDate="2016-03-11T05:48:13.443" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26043" PostTypeId="2" ParentId="26039" CreationDate="2016-03-11T06:58:53.807" Score="15" Body="&lt;p&gt;The answers to &lt;a href=&quot;https://aviation.stackexchange.com/questions/1672/how-effective-are-modern-aircraft-at-clearing-smoke&quot;&gt;this question&lt;/a&gt; indicate that these are the exhaust vents for the cabin air circulation. I think they appear to be much too large for just that purpose. I don't have a technical reference for this, but I believe those vents also prevent the cabin floor buckling in the event of a sudden pressurization failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cargo hold is beneath the passenger cabin, and both are pressurized because the cylindrical hull can resist pressure better than the flat cabin floor. If the cabin suddenly loses pressure the air in the hold could buckle the floor upward, or if the hold loses pressure the air in the cabin could buckle the floor downward. The floor must be generously vented to prevent this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;US patents # 6129312 and # 5137231 claim systems for combining the cabin air circulation vents with the depressurization relief vents. From the '9312 patent:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An air return grille mounted below the passenger cabin sidewall&#xA;  comprises openings to allow return airflow from the air conditioning&#xA;  system. The grille openings are covered by a single thin baffle with&#xA;  cutouts within its periphery that slip over and are held in place by&#xA;  fasteners on the molded grille. During normal operation, the thin&#xA;  baffle restricts flow through a small opening in the grille. During a&#xA;  sudden decompression of the cargo compartment, the baffle is dislodged&#xA;  from the fasteners. This allows the airflow to pass through all of the&#xA;  molded grille openings in order to achieve rapid pressure&#xA;  equalization.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="453" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-03-11T13:24:04.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26044" PostTypeId="2" ParentId="26036" CreationDate="2016-03-11T07:57:30.140" Score="5" Body="&lt;p&gt;I would think the OAT in the example is what your on-board thermometer is showing, so at 12,500 ft, not at sea level. ISA is +15°C at sea level, but at 12,500 ft it is &lt;a href=&quot;http://www.wolframalpha.com/input/?i=temperature+at+12500+ft+standard+atmosphere&quot; rel=&quot;noreferrer&quot;&gt;-9.8°C&lt;/a&gt;, so you are just -10 off ISA. Let's see. 4 ⋅ 12.5 ⋅ (−10) = −500, so the formulas match.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note though, that this is still just an approximation. The temperature lapse rate might also differ and that would have to be taken into account as well. The more precise equation is also nonlinear.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-03-11T07:57:30.140" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26045" PostTypeId="1" CreationDate="2016-03-11T08:44:28.467" Score="0" ViewCount="336" Body="&lt;p&gt;Is it possible to in-flight receive navigation data on an electronic device (like smartphone and/or tablet) present in the cockpit?&#xA;I refer to General Aviation aircraft and navigation data like airspeed (not groundspeed), GPS and AHRS data.&lt;/p&gt;&#xA;" OwnerUserId="13903" LastEditorUserId="12220" LastEditDate="2016-03-11T15:27:26.180" LastActivityDate="2016-03-14T09:31:35.563" Title="How can I get General Aviation flight data on smartphone and/or tablet?" Tags="&lt;general-aviation&gt;&lt;navigation&gt;&lt;flight-instruments&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26047" PostTypeId="1" AcceptedAnswerId="26048" CreationDate="2016-03-11T09:30:57.717" Score="10" ViewCount="2161" Body="&lt;p&gt;This morning's METAR for Cambridge looked like this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;EGSC 110720Z 11001KT 0150 &lt;b&gt;R23/0200N R05/0175N&lt;/b&gt; FZFG BKN001 M02/M02 Q1028&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Note the bold runway visual range (RVR) indications. What does the &lt;code&gt;N&lt;/code&gt; mean?&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2016-03-11T15:31:31.400" LastActivityDate="2016-03-11T15:31:31.400" Title="What does N mean after a runway visual range (in a METAR)?" Tags="&lt;metar&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26048" PostTypeId="2" ParentId="26047" CreationDate="2016-03-11T09:30:57.717" Score="10" Body="&lt;p&gt;RVR often has a letter at the end to indicate the visibility trend, so you can tell if it's going to improve (and maybe you should circle overhead for a while) or worsen (and you should consider going to your alternate).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;U&lt;/code&gt; means an &quot;upward&quot; trend: visibility is improving. &lt;code&gt;D&lt;/code&gt; means a &quot;downward&quot; trend: visibility is worsening. &lt;code&gt;N&lt;/code&gt; means &lt;strong&gt;no change&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-03-11T09:30:57.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26049" PostTypeId="2" ParentId="26045" CreationDate="2016-03-11T09:37:14.600" Score="2" Body="&lt;p&gt;&lt;em&gt;EDIT: This answer applies to large commercial aircraft.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a normal passenger? No. As @mins said, this data is captured, processed, and displayed within the aircraft's avionics system, but this data is not available to passengers (it's not transmitted outside the avionics system). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When aircraft are being developed and the manufacturers perform flight tests, then they will install special gateways into the avionics, allowing the test engineers in flight and on the ground to monitor aircraft parameters outside the cockpit - but this equipment is removed long before aircraft are sold to an airline.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best you can do is to use your own sensors - e.g. the GPS on your phone, a separate accelerator/gyro module - to generate your own position and attitude data. However, it will have a worse accuracy than the aircraft-level sensors, and there are certain parameters (e.g. airspeed) which you won't be able to obtain.  &lt;/p&gt;&#xA;" OwnerUserId="1478" LastEditorUserId="1478" LastEditDate="2016-03-14T09:31:35.563" LastActivityDate="2016-03-14T09:31:35.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26050" PostTypeId="1" CreationDate="2016-03-11T10:57:49.200" Score="4" ViewCount="382" Body="&lt;p&gt;Premise: In level unaccelerated flight we have relation $W=L=\frac{1}{2}\cdot\rho\cdot V_{stall}^2\cdot S\cdot C_{L,max}$ (taken from book Daniel P Raymer &quot;Aircraft Design: A Conceptual Approach&quot; equation (5.5) at page 85).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question: Why $C_{L,max}$? Why not $C_{L,min}$? In fact in case the $C_L$ in use is not $C_L,max$, and speed is little more than $V_{stall}$ (valued for $C_{L,max}$), it happen that Lift is not enough and anyway stall happens on aircraft. If using $C_{L,min}$ the calculation is more cautious.&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="4108" LastEditDate="2016-03-11T11:15:49.613" LastActivityDate="2019-08-14T13:28:12.417" Title="For calculating $V_{stall}$, why should be used $C_{L,max}$ and not $C_{L,min}$ (that would be more prudent)?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;aircraft-performance&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26051" PostTypeId="2" ParentId="26050" CreationDate="2016-03-11T11:35:12.007" Score="1" Body="&lt;p&gt;The stall speed is the speed at which you can still fly the plane in &lt;strong&gt;level flight&lt;/strong&gt;. This is important, because strictly speaking, stall happens at a certain angle of attack, not at a certain speed. In other words, you can safely fly a plane way below stall speed - the problem is that you'll be doing it nose-down in order to keep the angle of attack to a minimum (and that as such you will quickly exceed the stall speed again - hey, we just did a stall recovery maneuver!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, let's see what happens when we approach stall speed from a higher speed, while flying level. As we slow down, we must increase our angle of attack to maintain level flight - this way, we are increasing the $C_L$ of the wing, as to keep the lift $L(=W)=\frac{1}{2}\rho VSC_L$ constant when reducing our $V$. Ideally, we'd like to keep increasing our $C_L$ as we reduce our $V$ - however, this means we keep increasing our AoA (angle of attack) until it gets past a critical point, where the airfoil stalls due to flow separation at the suction side of the airfoil.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So really, using $C_{L,min}$ would be nonsensical - if your wings would have a lift coefficient so low at such a low speed, I can &lt;strong&gt;guarantee&lt;/strong&gt; you that $W&amp;gt;L$, i.e., you plummet from the skies. We &lt;strong&gt;need&lt;/strong&gt; to increase our $C_L$ to maintain level flight, and the stall speed is exactly the point where we can no longer increase our $C_L$, or in other words, we arrived exactly at $C_{L,max}$.&lt;/p&gt;&#xA;" OwnerUserId="4108" LastActivityDate="2016-03-11T11:35:12.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26052" PostTypeId="2" ParentId="7849" CreationDate="2016-03-11T11:37:14.550" Score="6" Body="&lt;p&gt;The B777-300 has a Ground Maneuvering Camera System (GMCS) which can be displayed in the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is mainly used to aid in turns (due to the length of the fuselage), but also works well for keeping it on the center line in straight ahead taxing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/Bk6-GlfYIi4?t=44s&quot; rel=&quot;noreferrer&quot;&gt;Ground Camera Video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aT0yO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aT0yO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-11T11:50:38.987" LastActivityDate="2016-03-11T11:50:38.987" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26053" PostTypeId="2" ParentId="26050" CreationDate="2016-03-11T11:44:21.040" Score="0" Body="&lt;p&gt;There are multiple stall speeds that have been defined. For example, the &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;SID=f553dbb9c06409a040f3d6865e435c70&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:1.0.1.1.1.0.1.2&amp;amp;idno=14;cc=ecfr&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §1.2 Abbreviations and symbols&lt;/a&gt; lists the following stall speeds:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{S}$&lt;/span&gt; means the stalling speed or the minimum steady flight speed at which the airplane is controllable.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{SO}$&lt;/span&gt; means the stalling speed or the minimum steady flight speed in the landing configuration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{S1}$&lt;/span&gt; means the stalling speed or the minimum steady flight speed obtained in a specific configuration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{SR}$&lt;/span&gt; means reference stall speed.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{SRO}$&lt;/span&gt; means reference stall speed in the landing configuration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{SR1}$&lt;/span&gt; means reference stall speed in a specific configuration.&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$V_{SW}$&lt;/span&gt; means speed at which onset of natural or artificial stall warning occurs.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;What you're asking is the &lt;span class=&quot;math-container&quot;&gt;$V_{S}$&lt;/span&gt;, the minimum flight speed at which the airplane is controllable. In short, as &lt;span class=&quot;math-container&quot;&gt;$V_{stall} \propto \sqrt{\frac{1}{C_{L}}}$&lt;/span&gt;, &lt;span class=&quot;math-container&quot;&gt;$C_{L_{max}}$&lt;/span&gt; gives the minimum speed at which the aicraft is controllable.&lt;/p&gt;&#xA;&lt;p&gt;Consider an aircraft in a level flight, If the pilot wants to reduce the speed, in order to maintain a steady, level flight, he/she has to increase the angle of attack i.e. increase the &lt;span class=&quot;math-container&quot;&gt;$C_{L}$&lt;/span&gt;. He can do this till the &lt;span class=&quot;math-container&quot;&gt;$C_{L}$&lt;/span&gt; reaches &lt;span class=&quot;math-container&quot;&gt;$C_{L_{max}}$&lt;/span&gt;, where the speed becomes minimum while the aircraft is still in a steady, level flight. If the speed is reduced any further, the aircraft loses lift; this speed gives the stall speed of the aircraft.&lt;/p&gt;&#xA;&lt;p&gt;You can get the stall speed for any configuration by using the &lt;span class=&quot;math-container&quot;&gt;$C_{L}$&lt;/span&gt; at that configuration; but the values have to be realistic. Setting the &lt;span class=&quot;math-container&quot;&gt;$C_{L}$&lt;/span&gt; to very low values to get large &lt;span class=&quot;math-container&quot;&gt;$V_{stall}$&lt;/span&gt; makes no physical or practical sense. For example, the aircraft can be set to have zero (or even negative) &lt;span class=&quot;math-container&quot;&gt;$C_{L_{min}}$&lt;/span&gt;, in which case, the stall speed has no meaning.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-11T11:44:21.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26056" PostTypeId="2" ParentId="26045" CreationDate="2016-03-11T14:31:17.187" Score="0" Body="&lt;p&gt;Yes but only with certain avionics. &lt;a href=&quot;http://www.avidyne.com/news/press.asp?release=320&quot; rel=&quot;nofollow&quot;&gt;Avidyne recently released an SDK&lt;/a&gt; that allows third party developers (tablet/smart phone) to interface with their &lt;a href=&quot;http://www.avidyne.com/products/ifd/index.html&quot; rel=&quot;nofollow&quot;&gt;IDF440 and 540 units&lt;/a&gt;. There are two levels of access (read only and read/write) that an app can have for the data stream. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2016-03-11T15:50:12.000" LastActivityDate="2016-03-11T15:50:12.000" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26057" PostTypeId="2" ParentId="26045" CreationDate="2016-03-11T14:31:32.733" Score="3" Body="&lt;p&gt;Garmin has a product called &lt;a href=&quot;http://www8.garmin.com/aviation/brochures/connext.pdf&quot; rel=&quot;nofollow&quot;&gt;Connext&lt;/a&gt; that allows you to stream in-flight avionics data to mobile devices. They are pushing that product as a move towards connected components and a &quot;Bring your own device&quot; approach to cockpit automation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So is it possible in general to receive it? No, not really. Not unless the avionics package was designed to broadcast it out. As other answers have said, a simple GPS and AHRS integration of the sensors in your tablet/smartphone can give a pretty good approximation of the data you are asking for, but things like airspeed, navigation waypoints, and other on-board sensor data are not generally available without a product like Connext. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other side of it is that if you are a passenger you still probably won't be able to pair with the avionics. Connext allows you to modify the flight plan via a mobile device, and I'm not sure I would want any of my passengers doing that. On top of that, pilots are trained to interpret the data at hand, you don't want a passenger seeing a faulty artificial horizon after a vacuum failure and think that the aircraft is tumbling out of the sky. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a lot of security concerns as it is over being able to hack into commercial aircraft (I know you are talking about GA), but I still don't want a passenger to have the ability to connect to my avionics.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-03-11T14:31:32.733" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26058" PostTypeId="1" AcceptedAnswerId="26060" CreationDate="2016-03-11T15:04:26.660" Score="8" ViewCount="9793" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q4br3.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q4br3.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am unsure of how to operate within this area (red dashed line) without connection to ATC.  It appears to come off of class D airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone provide an explanation of what this area is and how to operate within it?&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="14957" LastEditDate="2016-08-25T19:25:01.720" LastActivityDate="2021-05-06T11:25:10.653" Title="How should I operate within the dashed magenta lines next to Class D airspace?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;&lt;aeronautical-charts&gt;&lt;class-d-airspace&gt;&lt;class-e-airspace&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26059" PostTypeId="2" ParentId="26058" CreationDate="2016-03-11T15:14:33.517" Score="10" Body="&lt;p&gt;The area inside those lines is &lt;a href=&quot;http://flighttraining.aopa.org/pdfs/VFR_Chart_Symbols.pdf&quot; rel=&quot;noreferrer&quot;&gt;class E from the surface&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i4yXG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i4yXG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-03-11T15:14:33.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26060" PostTypeId="2" ParentId="26058" CreationDate="2016-03-11T15:15:09.907" Score="8" Body="&lt;p&gt;Its an area of Class-E airspace used for Instrument Approach Procedures. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2014.pdf&quot;&gt;The Pilot Handbook, Chapter 14, Airspace&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Class D airspace is generally airspace from the surface to&#xA;  2,500 feet above the airport elevation (charted in MSL)&#xA;  surrounding those airports that have an operational control&#xA;  tower. &lt;strong&gt;The configuration of each Class D airspace area is&#xA;  individually tailored and when instrument procedures are&#xA;  published, the airspace is normally designed to contain the&#xA;  procedures. Arrival extensions for instrument approach&#xA;  procedures (IAPs) may be Class D or Class E airspace.&lt;/strong&gt; Unless&#xA;  otherwise authorized, each aircraft must establish two-way&#xA;  radio communications with the ATC facility providing air&#xA;  traffic services prior to entering the airspace and thereafter&#xA;  maintain those communications while in the airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis Mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also from that handbook, the procedures for operating in Class-E:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If the airspace is not Class A, B, C, or D, and is controlled&#xA;  airspace, then it is Class E airspace. Class E airspace extends&#xA;  upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace. When designated&#xA;  as a surface area, the airspace is configured to contain all&#xA;  instrument procedures. Also in this class are federal airways,&#xA;  airspace beginning at either 700 or 1,200 feet above ground&#xA;  level (AGL) used to transition to and from the terminal or&#xA;  en route environment, and en route domestic and offshore&#xA;  airspace areas designated below 18,000 feet MSL. Unless&#xA;  designated at a lower altitude, Class E airspace begins at&#xA;  14,500 MSL over the United States, including that airspace&#xA;  overlying the waters within 12 NM of the coast of the 48&#xA;  contiguous states and Alaska, up to but not including 18,000&#xA;  feet MSL, and the airspace above FL 600.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically class-E rules apply, but be aware you are operating in an Instrument Approach Procedure area.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-03-11T15:15:09.907" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26061" PostTypeId="1" AcceptedAnswerId="26062" CreationDate="2016-03-11T15:42:58.300" Score="16" ViewCount="2877" Body="&lt;p&gt;Watching &lt;a href=&quot;http://www.aeronewstv.com/en/events/crash/3209-spectacular-slowed-fall-of-a-cirrus-sr22.html&quot;&gt;this video&lt;/a&gt; I notice there is a big hole in the middle of the parachute, at its top when deployed. This feature seems to exist in &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:A_member_of_the_Army&amp;#39;s_82nd_Airborne_Division_Fort_Bragg,_North_Carolina,_parachutes_to_the_ground_at_Charleston_Air_Force_Base_after_jumping_from_a_C-17_Globemaster_III,_15th_Airlift_Squadron_Charleston_AFB_010809-F-JQ435-009.jpg&quot;&gt;other smaller parachutes&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me, it seems that air can escape the parachute by this hole and thus the parachute is less efficient than a same-sized parachute without this hole. But it must serve in a way I don't imagine. What is its purpose?&lt;/p&gt;&#xA;" OwnerUserId="3394" LastEditorUserId="12220" LastEditDate="2016-03-11T18:08:33.660" LastActivityDate="2016-03-12T17:52:14.903" Title="What is the purpose of the hole in the Cirrus SR22's parachute?" Tags="&lt;general-aviation&gt;&lt;parachute&gt;&lt;airframe-parachute&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26062" PostTypeId="2" ParentId="26061" CreationDate="2016-03-11T15:46:30.130" Score="38" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;For me, it seems that air can escape the parachute by this hole&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's the point, air HAS to escape the parachute anyway, and without the hole it would do so laterally and in an uneven fashion, leading to lateral oscillations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hole allows the air to escape in a controlled location, avoiding undesired and possibly dangerous oscillations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some (most personal ones, but for example not the SR22 one) parachutes have handles that allow the user to deform the parachute: this allows some extra air to escape from the desired side, giving lateral controllability.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-03-11T15:52:20.337" LastActivityDate="2016-03-11T15:52:20.337" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26063" PostTypeId="1" AcceptedAnswerId="26064" CreationDate="2016-03-11T15:51:40.353" Score="11" ViewCount="1527" Body="&lt;p&gt;&lt;strong&gt;This question is not about how to decode METARs or what software or tools can be used to decode METARs. It is about why we are still using METARs today.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Given that we have smartphones with video messaging capability, cloud services with machine learning today, I struggle to understand why we are still reading METARs:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It is difficult to read. Sure it is not hard to learn, but the fact that you have to learn it means it's not intuitive&lt;/li&gt;&#xA;&lt;li&gt;It is designed at an age when text are transmitted by telegraph and every character counts&lt;/li&gt;&#xA;&lt;li&gt;It is trivial to program a parser and render more friendly messages&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For me I always feel that METARs are meant for machines; there has &lt;em&gt;got&lt;/em&gt; to be something better for pilots which happens to be human. Instead of having this on my flight plan:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;KSFO 111456Z 16015KT 9SM RA FEW012 SCT030 OVC070...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Why not just:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Station: KSFO&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Time: Mar 11 14:56 UTC&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Wind: 160 degrees, 15 knots&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Visibility: 9 statue miles&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Weather condition: rain&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Clouds: few at 1,200 feet; scattered at 3,000 feet; overcast at 7,000&#xA;  feet&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The problem is not about decoding them. Most pilots can read them, and by the time a new pilot completes his PPL training he should have no trouble reading either. The point is &lt;em&gt;everybody around the world is reading them, today, in the 21st century!&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if I'm the only one, but processing the METAR string during flight prep takes a couple of instruction cycles away from my brain (and I have a tendency to check whether the software got it right if I happen to be using one, so I will be processing it anyway, which is a good habit I suppose). I am sure some of that brain power can be better spent somewhere else: reading section charts, route planning, picking an alternate, etc. Scaling this to the global scale? It means every pilot is paying more attention to other things, as opposed to reading coded weather strings which really is the job of a machine. The result? Better flight safely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, why haven't we began the move?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3201" LastEditDate="2016-03-11T20:12:47.233" LastActivityDate="2019-02-22T19:51:36.830" Title="Why don't we get more user-friendly weather reports than METARs?" Tags="&lt;weather&gt;&lt;flight-planning&gt;&lt;metar&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26064" PostTypeId="2" ParentId="26063" CreationDate="2016-03-11T15:58:08.457" Score="7" Body="&lt;p&gt;If it ain't broke... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For what its worth many new aviation apps like ForeFlight and the such display the information in user friendly formats. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SLQ4U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SLQ4U.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.airmart.com/sites/default/files/maps-radar.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be honest I have not decoded a &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; in some time. You are correct that the system comes from a time when transmission bandwidth was not what it is today. Keep in mind things in aviation are slow to change and many other nations also report weather in the &lt;a href=&quot;https://i.stack.imgur.com/SLQ4U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; format so its useful to know how to read one if you fly abroad where they don't have the kind of infrastructure and applications we have available here in the US. Since official bodies like NOAA and the FAA broadcast &lt;a href=&quot;https://i.stack.imgur.com/SLQ4U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;METARS&lt;/a&gt; its far easier for a company like &lt;a href=&quot;http://foreflight.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ForeFlight&lt;/a&gt; to parse and display what they can already get than try to make the government change the format. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would love to see a broadcast of the &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; data in easy to read JSON format....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;https://pypi.python.org/pypi/metar/&quot; rel=&quot;nofollow noreferrer&quot;&gt;some packages out there for dealing with them in software&lt;/a&gt; if you need to. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also something to be said for a format that can easily be transmitted over various communication mediums. While morse code is not that popular anymore and most things are broadcast digitally the &lt;a href=&quot;https://i.stack.imgur.com/SLQ4U.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; format would still allow the information to be transmitted as is, in the event one of the more modern systems failed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the question has been edited a bit ill expand my answer to reflect. There really is no reason to change the format since most places you get the METAR from decode it for you anyway these days. While it has been pointed out there are some quick things that can be determined from reading them in their current format there is no information that is planed to be added to them so there is no reason to change (or expand) the format. A great deal of infrastructure exists around producing and decoding them as is, which would be a large task to overhaul and in the end produce nothing different than what exists now. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-11T19:08:21.123" LastActivityDate="2016-03-11T19:08:21.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26065" PostTypeId="2" ParentId="26063" CreationDate="2016-03-11T16:26:09.153" Score="12" Body="&lt;p&gt;One &lt;a href=&quot;https://en.wikipedia.org/wiki/Use_case&quot;&gt;use case&lt;/a&gt; where the compact METAR format is tough to beat is rapidly scanning meteorological trends. For that purpose, METARs are user friendly in the sense that they are &lt;em&gt;expert&lt;/em&gt; friendly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, a friend invited me to fly with him today on an &lt;a href=&quot;http://www.angelflightsoars.org/&quot;&gt;Angel Flight&lt;/a&gt; mission that would have required a landing at Nashville. We had to scrub because the weather is unfavorable and not getting any better according to the TAF and &lt;a href=&quot;https://www.aviationweather.gov/metar/data?ids=KBNA&amp;amp;format=raw&amp;amp;date=0&amp;amp;hours=3&quot;&gt;ADDS METAR Data&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;b&gt;Data at: 1616 UTC 11 Mar 2016&lt;/b&gt;&#xA;KBNA 111553Z 36006KT 1SM R02L/4000V6000FT -DZ BR OVC005 14/12 A3024 RMK AO2 DZB51 SLP239 P0000 T01390122 $&#xA;KBNA 111541Z 35005KT 1SM BR OVC005 14/12 A3024 RMK AO2 SFC VIS 1 1/2 $&#xA;KBNA 111527Z 01006KT 2SM BR OVC005 14/12 A3022 RMK AO2 SFC VIS 2 1/2 $&#xA;KBNA 111453Z 02008KT 3SM BR OVC005 14/12 A3021 RMK AO2 SLP227 T01390122 53015 $&#xA;KBNA 111451Z 02007KT 3SM BR OVC005 14/12 A3021 RMK AO2 $&#xA;KBNA 111434Z 01007KT 2SM BR OVC004 14/12 A3020 RMK AO2 $&#xA;KBNA 111353Z 02007KT 5SM BR OVC004 14/12 A3019 RMK AO2 SLP219 T01390122 $&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;A subsecond scan confirms that the low overcast ceiling is stuck at four to five hundred feet AGL for the past several hours. Try outdoing that using the same information in &lt;a href=&quot;https://www.aviationweather.gov/metar/data?ids=KBNA&amp;amp;format=decoded&amp;amp;hours=3&amp;amp;taf=off&amp;amp;layout=on&amp;amp;date=0&quot;&gt;decoded METAR format&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-03-11T16:47:18.477" LastActivityDate="2016-03-11T16:47:18.477" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26067" PostTypeId="2" ParentId="26030" CreationDate="2016-03-11T16:54:53.190" Score="6" Body="&lt;p&gt;The range of the VOR is included in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airport/Facility Directory&lt;/a&gt; data under the name &lt;em&gt;class&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;From A/FD legend:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vX5GO.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vX5GO.png&quot; alt=&quot;Navaid class in A/FD&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Example:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fVglS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fVglS.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Service volume for each class:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2dRlY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2dRlY.png&quot; alt=&quot;Navaid service volume by class&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2021-03-08T08:36:56.957" LastActivityDate="2021-03-08T08:36:56.957" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26069" PostTypeId="2" ParentId="26063" CreationDate="2016-03-11T17:43:53.347" Score="3" Body="&lt;p&gt;Because the METAR format is standardized and a large number of systems know how to read and process them. Lots of applications consume METAR data, from weather websites to ACARS terminals in cockpits to pilots' brains. An application can read in METAR data from many stations and use it to produce, say, a map of winds across a region or a graph of temperatures over time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all works because everyone has a common understanding of the format, and there are a number of code libraries for major programming languages that assist in generating and parsing the METAR format. If you change the format to be human readable, all of that breaks. As with many popular standards, changing it would require the immediate global cooperation of everyone at once. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes far more sense to keep the METAR format as it is (or to extend it with new elements to accommodate new reporting needs) and build tools to present the information in user friendly ways, as ForeFlight and many others do.&lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2016-03-11T17:43:53.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26072" PostTypeId="1" AcceptedAnswerId="26074" CreationDate="2016-03-11T19:19:54.740" Score="0" ViewCount="215" Body="&lt;p&gt;I've recently discovered the device named &lt;a href=&quot;http://www.aviation.levil.com/ilevil-2-aw.html&quot; rel=&quot;nofollow&quot;&gt;Levil 2 AW&lt;/a&gt; which gives complete navigation functionalities, including Air Data computations once it is connected to the pitot-static system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this regard, generally speaking, is it really so easy to connect to the aircraft pitot-static system as it appears from both product description and related videos?&lt;/p&gt;&#xA;" OwnerUserId="13903" LastEditorUserId="14897" LastEditDate="2016-06-17T01:35:16.737" LastActivityDate="2016-06-17T01:35:16.737" Title="How easy is it to make a connection to the aircraft pitot-static system?" Tags="&lt;pitot-static&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26073" PostTypeId="1" AcceptedAnswerId="26076" CreationDate="2016-03-11T19:37:02.937" Score="21" ViewCount="1445" Body="&lt;p&gt;In this image of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_X-29&quot; rel=&quot;nofollow noreferrer&quot;&gt;Grumman X-29&lt;/a&gt;, there is an 'arm' just above the exhaust nozzle leading forward and, apparently, attached to the right side of the fuselage. What is this and what is it for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C3K44.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C3K44.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_X-29&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-29 Article&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize this is an experimental aircraft, but it doesn't look like sensors (like the probe off the nose), it looks more like a structure for lifting the plane.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="15311" LastEditDate="2017-12-04T11:43:30.757" LastActivityDate="2017-12-04T11:43:30.757" Title="What is the 'arm' at the rear of the X-29?" Tags="&lt;aircraft-design&gt;&lt;experimental-aircraft&gt;&lt;x-29&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26074" PostTypeId="2" ParentId="26072" CreationDate="2016-03-11T19:43:14.200" Score="2" Body="&lt;p&gt;It's very easy to connect a component to the pitot and static systems: It's literally just basic plumbing (install a T fitting and connect the lines). For IFR certified aircraft a static system test will also be required (and a pitot pressure leakdown test would be advisable if the pitot system is opened).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulatory issues surrounding the installation are more complex regarding what kinds of devices may be installed on a certificated airframe and under what conditions they such devices could be used as a primary or standby reference for flying the aircraft, &lt;a href=&quot;https://aviation.stackexchange.com/questions/26072/connection-to-the-aircraft-pitot-static-system#comment62949_26072&quot;&gt;as Ron alluded to&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-03-11T19:43:14.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26075" PostTypeId="1" CreationDate="2016-03-11T19:47:54.517" Score="5" ViewCount="295" Body="&lt;p&gt;I am looking at some data form the BTS and trying to understand some spikes in month to month Volume delays. From my understanding a Volume delay is due to the volume of airplanes, causing the ATC to manage more take offs and landings and therefore slowing down the whole process.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My problem is that for volume delays bts only provides monthly aggregates. So I have data with a spike for Volume but the number of flights on that same month is normal or sometimes less than average. So I am assuming that something is happening at the daily level that is completely lost in the aggregation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This all boils down to my question. If we where to quantify the capacity of the airspace around say ORD and call it X and on average the airspace is occupied with N planes, such that N &amp;lt; X and airspace is operating at N/X capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On days following mass delays or large number of cancellations, does the amount of planes in the airspace increase to alleviate the pressure of passengers who are behind schedule? or does the load factor simply increase?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For examples say that on average airspace at ORD operates at 75% capacity, then one day you have some event that causes a lot of delays and cancellations. Do the following days operate at say 90% airspace capacity to help relive that congestion? or do they still operate the same number of planes but those planes are simply almost guaranteed to be full.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All summed up, would a spike in delays for some reason other than plane volume result in a spike in volume delay in the following days as they deal with the extra passengers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry if this question is worded strange, I had a hard time putting it down in writing. If its unclear let me know and I'll try to clarify.&lt;/p&gt;&#xA;" OwnerUserId="13962" LastEditorUserId="13197" LastEditDate="2016-04-20T15:13:53.957" LastActivityDate="2016-04-20T15:13:53.957" Title="Is airspace more crowded on days following cancellations or a large number of delays?" Tags="&lt;air-traffic-control&gt;&lt;airline-operations&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26076" PostTypeId="2" ParentId="26073" CreationDate="2016-03-11T19:56:44.063" Score="25" Body="&lt;p&gt;Two X-29's were built, and the only difference between the two is that #2 has an externally mounted spin recovery chute attached to the tail. That is what you are seeing in this picture. The chute is packed in the tube structure and the &quot;arms&quot; are structural to distribute load.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://fas.org/man/dod-101/sys/ac/x-29.htm&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The only significant difference between the two aircraft was an emergency spin chute deployment system mounted at the base of the rudder on aircraft No. 2.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=0PrtM1weNOE&quot;&gt;Here is a video of the chute deployed&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/centers/dryden/multimedia/imagegallery/X-29/EC89-216-5.html&quot;&gt;And here are more details from NASA on the chute system&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason that #2 needed this and #1 did not is that #2 was going to be conducting experiments at up to 67° angle of attack, where entering a spin was much more likely. #1's AOA was limited to about 21° and was considered the &quot;phase-1&quot; flight dynamics platform, while #2 was the &quot;phase-2&quot; platform.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-11T22:26:00.937" LastActivityDate="2016-03-11T22:26:00.937" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26078" PostTypeId="1" AcceptedAnswerId="26083" CreationDate="2016-03-11T20:48:37.947" Score="8" ViewCount="2019" Body="&lt;p&gt;The Buran &lt;a href=&quot;http://www.dailymail.co.uk/sciencetech/article-3119861/Russia-s-forgotten-space-agency-Haunting-images-reveal-two-abandoned-Soviet-shuttles-rotting-giant-derelict-hangar.html&quot; rel=&quot;noreferrer&quot;&gt;had a very sad fate&lt;/a&gt;. But in 1988 it has undertaken its &lt;a href=&quot;https://www.youtube.com/watch?v=ikxwNCcKREY&quot; rel=&quot;noreferrer&quot;&gt;first and last flight&lt;/a&gt;, which was &lt;a href=&quot;https://en.wikipedia.org/wiki/Buran_%28spacecraft%29#Orbital_flight&quot; rel=&quot;noreferrer&quot;&gt;unmanned&lt;/a&gt; and landed with a precision of three meters in a crosswind of 60 km per hour. It lost only 8 of its 38 000 thermal tiles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What was the level of technology of automated flights in that times? Was it usual that airplanes landed automatically or was that flight of the Buran something like exceptional? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an image of the Buran with Energija launch vehicle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OB9Pu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OB9Pu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Buran_%28spacecraft%29#/media/File:Buran.jpg&quot; rel=&quot;noreferrer&quot;&gt;source of the image&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="13431" LastEditDate="2016-03-11T21:26:37.443" LastActivityDate="2018-12-29T01:41:57.660" Title="Was the unmanned flight and landing of the Buran spacecraft in 1988 exceptional?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;space-shuttle&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26079" PostTypeId="1" AcceptedAnswerId="26081" CreationDate="2016-03-11T20:56:33.390" Score="4" ViewCount="441" Body="&lt;p&gt;After the parachute is deployed there is no control where the plane is going, so why didn't Cirrus make the SR-22's parachute steerable? &lt;/p&gt;&#xA;" OwnerUserId="3455" LastEditorUserId="5517" LastEditDate="2016-03-12T01:00:36.530" LastActivityDate="2016-03-12T01:00:36.530" Title="Why didn't Cirrus make the SR-22's parachute steerable?" Tags="&lt;airframe-parachute&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26080" PostTypeId="2" ParentId="19576" CreationDate="2016-03-11T22:04:46.750" Score="4" Body="&lt;p&gt;NFPA (National Fire Protection Agency) 409 - Standard for Aircraft Hangars states in each chapter that deals with the 4 types of Hangars:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;8.6.1*     Grounding facilities shall be provided for removal and control of static electrical accumulations on aircraft while aircraft&#xA;  are stored or are undergoing servicing in a hangar.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;8.6.2     Floor-grounding receptacles shall be provided and shall be either grounded through individual driven electrodes or electrically&#xA;  bonded together in a grid system and the entire system grounded to&#xA;  underground metal piping or driven electrodes. Where driven electrodes&#xA;  are used, they shall consist of 15.9 mm ( 5/8 in.) diameter or larger&#xA;  metal rods driven at least 1.5 m (5 ft) into the ground.&#xA;  Floor-grounding receptacles shall be designed to minimize the tripping&#xA;  hazard.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;8.6.3*     Grounding wires shall be bare and of a gauge that will be satisfactorily durable to withstand mechanical strains and usage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is not a law per se, unless one has adopted a code that references NFPA 409, but at the very least it is a recognized standard for best practices that will be used in a court of law after an incident.&lt;/p&gt;&#xA;" OwnerUserId="13979" LastEditorUserId="12720" LastEditDate="2016-03-11T22:18:24.340" LastActivityDate="2016-03-11T22:18:24.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26081" PostTypeId="2" ParentId="26079" CreationDate="2016-03-11T22:26:00.177" Score="9" Body="&lt;p&gt;Remember what the purpose of the CAPS/BRS airframe parachute is: It's a last-resort emergency measure to put the aircraft on the ground in a condition that is likely to be survivable for those onboard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Steerable parachutes add considerable complexity: Control lines would need to be routed into the cabin, and connected in such a way as to not interfere with the chute deployment under any circumstances.&lt;br&gt;&#xA;Assuming a suitable design could be devised to accomplish that a steerable parachute (even for a single person) requires quite a bit of training and skill to use. This is not something that can be adequately trained for in the case of the Cirrus airframe chute (because pulling the chute on perfectly good aircraft to teach steering would be cost-prohibitive).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Faced with the risks and complexity of a steerable chute or the relative simplicity and safety of a simple drag chute to decelerate the airframe prior to impact (hoping you land in a suitable 40-by-40 foot square) Cirrus and BRS opted for the latter. The result is a dead-simple &quot;Pull the handle!&quot; system that's proven very successful thus far.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-03-11T23:03:16.653" LastActivityDate="2016-03-11T23:03:16.653" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26082" PostTypeId="2" ParentId="5019" CreationDate="2016-03-11T22:45:18.440" Score="6" Body="&lt;p&gt;Q: &lt;em&gt;Could it fly between any two suitable airports on Earth, i.e. further than 20038km?&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A: &lt;em&gt;Not likely&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/S9lhU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/S9lhU.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="14897" LastEditDate="2017-02-15T17:54:56.187" LastActivityDate="2017-02-15T17:54:56.187" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26083" PostTypeId="2" ParentId="26078" CreationDate="2016-03-11T23:02:18.400" Score="12" Body="&lt;p&gt;Your question is very subjective, but I think there are two ways to look at it:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Building a working space plane is pretty exceptional.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;There's really nothing it did that wasn't done by something else.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The NASA shuttle was flown in fully-automatic mode for launch, and most of reentry. It's also the vehicle which pioneered the thermal tiles, the reentry profile of a space plane, and the general concept of a shuttle. Buran could almost be thought of as an iteration on that design. The Soviets used some lessons learned and, in some respects, built a better shuttle. Does that in itself make the Buran exceptional? Probably not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only thing Buran really did that the NASA shuttle never did was fly unmanned, including an automatic landing. That seems to be at the heart of what you're asking, so I'll address that specifically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Autoland&quot; rel=&quot;nofollow noreferrer&quot;&gt;Autoland&lt;/a&gt; had existed for decades before Buran, so it certainly wasn't the first airplane to land on autopilot. Although, it may have been the fastest autolanding to date, which could be an argument for exceptional.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would note that even though there was only one orbital flight of Buran, there were atmospheric tests of prototype vehicles (some prototypes had jet engines), so there were opportunities to safely test the autopilot during the landing phase of flight prior to the orbital test. In fact, it would have been the only phase of the autopilot that saw real-world testing prior to launch. So once Buran got on approach, the fact that landed safely probably shouldn't be too much of a surprise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, I've heard and read many times how amazing it is that Buran landed so close to centerline in such a dramatic crosswind (around 33 knots). I think that would indeed be pretty impressive... if it were true. However, I urge you to go look at video of Buran landing (&lt;a href=&quot;https://youtu.be/Q6WHjQ3Y3Uo?t=2m55s&quot; rel=&quot;nofollow noreferrer&quot;&gt;example&lt;/a&gt;, mute recommended). Does that look like a 33 knot crosswind to &lt;em&gt;any&lt;/em&gt; pilot? To me, it looks like about a 5-10 knot crosswind at most. You see the wings doing very little correcting, and the wheels touchdown at almost the same time, which is very much &lt;em&gt;not&lt;/em&gt; indicative of a crosswind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For comparison, take a look at &lt;a href=&quot;https://youtu.be/gZC1Qi4peOE?t=7&quot; rel=&quot;nofollow noreferrer&quot;&gt;STS-133 landing&lt;/a&gt;. Note the wing movement at 8:58 which is to correct for &lt;a href=&quot;http://www.spaceflightnow.com/shuttle/sts133/anniversary/&quot; rel=&quot;nofollow noreferrer&quot;&gt;about a 12-knot crosswind gust&lt;/a&gt;, which looks about right to me. Notice how the upwind wheel hits the runway about a second before the downwind wheel hits - very indicative of a crosswind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea where the crosswind number came from, but it was almost certainly exaggerated, either on accident (perhaps mistaking wind conditions on approach for surface wind), or intentionally exaggerated to show how great and superior Buran was. Either seems plausible to me.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I tend to be in the camp that says anything you build which successfully goes to space and comes back safely is pretty exceptional, but I wouldn't say Buran was a tremendous advancement over existing technology, and ultimately it's always going to be difficult to really assess a ship which only flew once.&lt;/p&gt;&#xA;" OwnerUserId="6" LastEditorUserId="6" LastEditDate="2018-12-29T01:41:57.660" LastActivityDate="2018-12-29T01:41:57.660" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26084" PostTypeId="1" AcceptedAnswerId="26145" CreationDate="2016-03-12T00:13:52.937" Score="10" ViewCount="1347" Body="&lt;p&gt;Considering a very long route (equal to the max ferry range of an aircraft[1]).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Would it be more fuel efficient to fly multiple legs or a single one ?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Multiple legs would allow you to use less fuel, decreasing weight and fuel consumption&lt;/li&gt;&#xA;&lt;li&gt;Single leg would dispense you having to go through multiples takeoffs and time increased at low, high drag altitude&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;How does theses balance ? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested into any real world aircraft[!].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[1]: Results might differ for each models so you can pick any you like.&lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="13197" LastEditDate="2016-04-27T21:19:25.017" LastActivityDate="2016-04-28T08:19:26.353" Title="When are multiple hops more efficient than single leg?" Tags="&lt;efficiency&gt;&lt;ferry-flight&gt;" AnswerCount="4" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26086" PostTypeId="2" ParentId="26030" CreationDate="2016-03-12T09:21:28.437" Score="2" Body="&lt;p&gt;From the chart you can understand what type of &lt;strong&gt;VOR&lt;/strong&gt; is that  But there are also other ways . By checking the frequency band you can also understand the type of that VOR.   There are basically two types of them and they are Terminal VOR(TVOR) and Airway VOR. The whole VOR frequency range is VHF-108 to 117.95MHz.  ILS frequency shares some portion of the TVOR. The terminal VOR are mainly of low and the airway VOR are mainly of high type. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;TVOR frequency band are from 108.00 to 112.00MHz. In details, TVOR uses even first decimal and even first decimal +50KHz upto 112MHz. Like 108.00MHz, 108.15MHZ, 108.20MHz, 108.25MHz etc&lt;/li&gt;&#xA;&lt;li&gt;and the ILS uses odd first decimal and odd first decimal +50KHz upto 112.00MHz. Like 108.10MHz, 108.15MHz,108.30MHz, 108.35MHz etc.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airway VOR uses the remainder of the frequency band 112.00MHz to 117.95MHz.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;other than this you can understand the VOR type from the chart the people has already shown.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13956" LastActivityDate="2016-03-12T09:21:28.437" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26087" PostTypeId="2" ParentId="26063" CreationDate="2016-03-12T10:23:27.750" Score="2" Body="&lt;p&gt;Other answers have addressed some of the reasons why the METAR transmission format should stick around. I'll add that there is a lot of machinery in place that would be expensive to replace in order to make such a change, so it wouldn't happen even if we wanted it to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If something was going to change, it could be to eliminate the testing requirement that all new pilots are able to read and interpret METARs. As has been pointed out, there are many applications both for devices and on the web that can translate them for you, including aviationweather.gov. So it's dubious reasoning to assert that a person cannot be a competent pilot unless they can interpret a METAR without assistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Useful skills should be trained, but only skills and knowledge required to be competent should be tested.&lt;/p&gt;&#xA;" OwnerUserId="9012" LastActivityDate="2016-03-12T10:23:27.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26089" PostTypeId="2" ParentId="26084" CreationDate="2016-03-12T13:43:43.170" Score="5" Body="&lt;p&gt;In a broad sense, if the flight distance is nearly equal to the max range of the aircraft, the route with shorter legs is prefereable from the point of fuel economy. The reason is simple- more the fuel you carry more the aircraft you have more weight, which requires more fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All other things being equal, the fuel caried is payload- one can see it as the aircraft carrying extra payload or as the fuel eating into the regular payload. Either way, the extra fuel carried impacts on the fuel effeciency of the aircraft negatively.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;According to &lt;a href=&quot;http://www.srs.aero/wordpress/wp-content/uploads/2010/11/NBAA-2010-Optimized-Planning.pdf&quot;&gt;this document&lt;/a&gt;, payload burns fuel at the rate of 2.5-5 % of its weight in fuel per flight hour. For the &lt;a href=&quot;https://en.wikipedia.org/wiki/Non-stop_flight#Currently_scheduled_.28top_30.2C_by_distance.29&quot;&gt;longest non-stop routes in service&lt;/a&gt;, the travel time is in the upwards of 15 hours. Taking a value of 3% fuel burn, this means that a significant portion of fuel consumption is actually to carry the fuel itself. This is a significant issue, especially when the oil prices are high.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The increased take off weight will result in more thrust requirement, TO length and time to climb (or more thrust again), adversely affecting the fuel consumption, while increasing engine wear.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;While it is true that the longer distance flights spend more time in altitudes with less drag, it is questionable whether that translates into any significant real world benifits. For example, the latest 777 ULR version has a higher aspect ratio to reduce drag, requiring the folding of wings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Of course, fuel use is only a part of the story. The other significant factor is time- most of the ultra long range flights are targeted towards business flyers, for whom the addition of more than 25% due to shorter legs may be unacceptable. In the end, the deciding factor may be the percentage of seats filled per flight. When SA cancelled the Singapore-Newark flight, &lt;a href=&quot;http://www.bloomberg.com/news/articles/2013-10-31/fuel-costs-lead-singapore-air-to-end-worlds-longest-nonstop-flights&quot;&gt;one analyst noted&lt;/a&gt;:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“The plane burns a lot of fuel but carries very few passengers,” says Siyi Lim, an analyst at OCBC Investment Research in Singapore. “It didn’t make sense to continue.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The ultra long distance flights also require additional facilities- extra crew for rotaion, extra food items carried etc. In general, the straight long distance routes have higher fares compared to the ones with stops in between. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-12T13:43:43.170" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26091" PostTypeId="1" AcceptedAnswerId="26113" CreationDate="2016-03-12T14:30:19.633" Score="15" ViewCount="2026" Body="&lt;p&gt;On the 747-200 the engines were tilted up to &quot;meet the air at a streamline angle&quot;:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8RrdV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8RrdV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://commons.m.wikimedia.org/wiki/File:Alitalia_Boeing_747-200_Bidini.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hYfMh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hYfMh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://commons.m.wikimedia.org/wiki/File:Boeing_747-212B,_Singapore_Airlines_AN0115851.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1VB2k.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1VB2k.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://www.rcgroups.com/forums/showthread.php?t=1778464&amp;amp;page=22&quot; rel=&quot;noreferrer&quot;&gt;RcGroups.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in the 747-8, the engines are not tilted up:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/HlNVy.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HlNVy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://airwaysnews.com/blog/2013/05/29/boeing-delivers-50th-boeing-747-8/&quot; rel=&quot;noreferrer&quot;&gt;Airways News&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anybody know why the engines are not tilted up anymore?&lt;br&gt;&#xA;Thanks!&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-12T20:10:54.437" LastActivityDate="2018-01-04T11:16:09.133" Title="Why are the 747-8 engines placed differently than on the older versions?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26092" PostTypeId="2" ParentId="26075" CreationDate="2016-03-12T14:43:38.100" Score="2" Body="&lt;p&gt;I would say generally no, because there are only so many landing slots available at busy airports and airlines frequently substitute larger aircraft to clear up a passenger backlog.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-03-12T14:43:38.100" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26094" PostTypeId="5" CreationDate="2016-03-12T16:49:59.740" Score="0" Body="&lt;p&gt;The Boeing 747-8 is the newest addition to the &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt; family. Compared to its predecessor, the 747-400, it has:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a lengthened &lt;a href=&quot;/questions/tagged/fuselage&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuselage&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuselage&lt;/a&gt; of 250ft / 76.3m making it the longest passenger aircraft in the world,&lt;/li&gt;&#xA;&lt;li&gt;new &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s with a larger wingspan of 224ft / 68.4m and raked wingtips,&lt;/li&gt;&#xA;&lt;li&gt;new General Electric GEnx &lt;a href=&quot;/questions/tagged/engine&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;engine&amp;#39;&quot; rel=&quot;tag&quot;&gt;engine&lt;/a&gt;s (also used on the &lt;a href=&quot;/questions/tagged/boeing-787&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-787&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-787&lt;/a&gt;) with chevrons,&lt;/li&gt;&#xA;&lt;li&gt;partial fly-by-wire controls,&lt;/li&gt;&#xA;&lt;li&gt;and many other 787-like upgrades to the traditional 747 airframe.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are two version of the 747-8:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The &lt;strong&gt;747-8I&lt;/strong&gt; (Intercontinental) is the passenger variant with a longer upper deck. It has a capacity of 467 passengers (3-class layout) and a range of 8000NM. 47 have been delivered as of June 2019.&lt;/li&gt;&#xA;&lt;li&gt;The &lt;strong&gt;747-8F&lt;/strong&gt; (Freighter) is the cargo variant with a shorter upper deck. It can carry up to 140t of payload and has a range of 4390NM. 87 have been delivered as of June 2019.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There will also be a replacement for the VC-25A (military variants of the 747-200) used by the US Air Force for presidential transport as &lt;a href=&quot;/questions/tagged/air-force-one&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;air-force-one&amp;#39;&quot; rel=&quot;tag&quot;&gt;air-force-one&lt;/a&gt; based on the 747-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more information, see Wikipedia's article: &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747-8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing 747-8&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="33692" LastEditDate="2019-08-20T16:01:35.717" LastActivityDate="2019-08-20T16:01:35.717" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26095" PostTypeId="4" CreationDate="2016-03-12T16:49:59.740" Score="0" Body="For questions specifically about the Boeing 747-8I or -8F models." OwnerUserId="12220" LastEditorUserId="33692" LastEditDate="2019-08-20T14:27:56.517" LastActivityDate="2019-08-20T14:27:56.517" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26096" PostTypeId="1" AcceptedAnswerId="26098" CreationDate="2016-03-12T16:58:53.340" Score="3" ViewCount="509" Body="&lt;p&gt;I would love to practice within towered airspace (approaches, touch and goes, ect.) However, I do not want to upset operations within the airspace.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the best way to determine when the best time to practice these maneuvers would be? Should I contact both the tower and TRACON?&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="9736" LastEditDate="2016-03-13T01:33:54.627" LastActivityDate="2016-03-13T12:38:43.383" Title="How can I find out the best time to practice within towered airspace?" Tags="&lt;air-traffic-control&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26097" PostTypeId="1" AcceptedAnswerId="26100" CreationDate="2016-03-12T17:05:32.467" Score="8" ViewCount="2471" Body="&lt;p&gt;Seems like an odd scenario, however I have experienced this a few times now.  A non-towered airport will have someone on the radio directing traffic and reading out weather info like barometric pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find this to be extremely dangerous and unwanted as the times I have encountered this, the person on the radio has no reason or training to do this (among other things).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question:  If faced with this scenario what would you do?  Would you report the airport?  Am I looking too much into this and should just let it go?&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="19" LastEditDate="2016-11-01T08:35:02.377" LastActivityDate="2019-02-18T02:11:37.923" Title="How does one deal with a UNICOM operator directing aircraft like at a towered airport?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;non-towered-airport&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26098" PostTypeId="2" ParentId="26096" CreationDate="2016-03-12T17:13:33.450" Score="9" Body="&lt;p&gt;Simplest answer: Call the tower. Or ask instructors/schools in the area if the controllers care when you arrive and want to practice. Usually if you arrive during the busiest time, you'll likely be accommodated as best as they can, but there's a chance you could be told to just do a full-stop taxi-back operation if that helps out or told to go fly around elsewhere for a bit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends on what airport you're thinking about going to. If you want to go to ATL, well, you'll be vectored in a gap, and told go as fast as you can for as long as you can, and be told to land(or if you go around, expect a long delay to find a new gap). If it's just a general aviation airport, anytime is fine.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-03-12T17:13:33.450" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26099" PostTypeId="2" ParentId="26061" CreationDate="2016-03-12T17:45:22.370" Score="6" Body="&lt;p&gt;In order for a parachute to move through the air, all of the air underneath it needs to move out of its way.  If a concave round parachute didn't have any kind of hole in it, it would fill with a convex mass of high-pressure air which would push air that was underneath it outward.  If it had an overly large hole, the air pressure would be accelerated inward but wouldn't face much resistance going there.  If a parachute has a properly-sized hole, the pressures that would push air inward and those which would push air outward will roughly balance, with the effect that as much air as possible will remain underneath the parachute as long as possible thus blocking its downward motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To be sure, it's not possible for a parachute to prevent all of the air below it (or even any of it) from moving horizontally at all, but reducing the outward pressure will greatly increase the time required for the air below the parachute to get out of its way, and thus improve the effectiveness of the parachute.&lt;/p&gt;&#xA;" OwnerUserId="973" LastEditorUserId="973" LastEditDate="2016-03-12T17:52:14.903" LastActivityDate="2016-03-12T17:52:14.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26100" PostTypeId="2" ParentId="26097" CreationDate="2016-03-12T18:00:22.283" Score="13" Body="&lt;p&gt;You're almost certainly talking about a &lt;a href=&quot;https://en.wikipedia.org/wiki/UNICOM&quot; rel=&quot;nofollow noreferrer&quot;&gt;UNICOM operator&lt;/a&gt;, who is just an airport (FBO) employee who gives information to pilots on their request. The FAA's Pilot Handbook &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/phak%20-%20chapter%2013.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;UNICOM is a nongovernment air/ground radio communication station which&#xA;  may provide airport information at public use airports where there is&#xA;  no tower or FSS. On pilot request, UNICOM stations may provide pilots&#xA;  with weather information, wind direction, the recommended runway, or&#xA;  other necessary information. If the UNICOM frequency is designated as&#xA;  the CTAF, it will be identified in appropriate aeronautical&#xA;  publications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The important point is that &lt;em&gt;UNICOM is not ATC&lt;/em&gt;. A UNICOM operator cannot give you instructions, clearances or require you to do anything. He can only give you information, and as PIC it's up to you to decide how to use that information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.aopa.org/asf/publications/inst_reports2.cfm?article=3895&quot; rel=&quot;nofollow noreferrer&quot;&gt;article&lt;/a&gt; that Porcupine911 &lt;a href=&quot;https://aviation.stackexchange.com/questions/26097/non-towered-airport-directing-aircraft-like-towered-airport#comment63014_26097&quot;&gt;mentioned&lt;/a&gt; is a great example of that. A student pilot thought that UNICOM was telling him which runway to land on, whereas in fact the operator was only recommending a runway (presumably based on the prevailing wind or whatever). Unfortunately, the operator recommended the opposite runway to the one that was actually in use by other pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like pilots, UNICOM operators vary in their experience and competence. A good UNICOM operator (in my opinion) will give you the local wind and altimeter information, tell you if there are other aircraft in the pattern or nearby, tell you which runway is in use by those aircraft, and give you any essential safety information (like a closed runway). But as PIC, I'm still going to listen to CTAF and AWOS and look for other traffic before choosing a runway and joining the pattern. It's also common for no one to reply to a UNICOM call (because the operator is out fueling aircraft in his other role as lineman, for example), in which case you're going to have to sort things out without it anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there's no need to &quot;report&quot; anything: UNICOM operators are a well-known and official service, but you have to know how to use them and what their limitations are.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-11-01T21:38:28.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26101" PostTypeId="1" AcceptedAnswerId="26114" CreationDate="2016-03-12T18:22:11.960" Score="14" ViewCount="2211" Body="&lt;p&gt;Why does it have anhedral wings and not &quot;normal&quot; wings? Many other similar aircraft with low-wing have dihedral wings.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Df4wW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Df4wW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://www.dassaultfalcon.com/en/Aircraft/PreOwned/Pages/Pre-owned_list.aspx&quot; rel=&quot;noreferrer&quot;&gt;DassaultFalcon.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: This is about the Falcon 900, which apparently has a low-wing design and it's not used for cargo like the An-225&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-11-16T22:36:18.730" LastActivityDate="2019-11-17T08:17:54.277" Title="Why does the Falcon 900 have anhedral wings?" Tags="&lt;aircraft-design&gt;&lt;dassault-falcon&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26102" PostTypeId="1" AcceptedAnswerId="26106" CreationDate="2016-03-12T19:41:59.490" Score="16" ViewCount="6876" Body="&lt;p&gt;I'm studying turbojets, turbofans, and turboprops. I can see that, for the latter engine configuration, a gearbox is necessary so that the propeller rotates at a lower velocity than the main compressor. Here is an image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5PvhA.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5PvhA.png&quot; alt=&quot;Turboprop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the experts in the aerospace field, my question might be regarded as a bit &quot;odd&quot;, but here I go: &lt;em&gt;is there any reason why we can't use a second turbine to move the propeller with coupled shafts, instead of relying on a gearbox?&lt;/em&gt; The idea would be to use a low pressure turbine that moved the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this might be unfeasible, because the added weight of a second turbine would be higher than the weight of the gearbox itself, but I don't know if there are additional considerations to this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on the positive side, we would have the following (and please, correct me if I'm wrong):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less maintenance work.&lt;/li&gt;&#xA;&lt;li&gt;Propeller rotation shaft aligned with the main engine core (does this &lt;em&gt;even&lt;/em&gt; represent an aerodynamic advantage?).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 1&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea would be using two turbines. A high-pressure turbine (HP) that moved the compressor, and a low-pressure (LP) turbine that moved the turboprop. My idea was taken from the turbofan engine config.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 2&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the user &lt;strong&gt;&lt;em&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/3201/mins&quot;&gt;mins&lt;/a&gt;&lt;/em&gt;&lt;/strong&gt; pointed out, we would need a very slow turbine or even a gearbox. But we could design the LP turbine with few stages (say 1, 2 or 3) so that its rotational velocity would be low enough as to move the propeller without having aerodynamic losses in the tips of the prop. And as this same user pointed out, there already exists such a configuration (see &lt;a href=&quot;http://theaviationist.com/2015/02/15/bear-contra-rotating-blades/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;). The question then is, why isn't this configuration preferred over the &quot;conventional&quot; one? (i.e. the one that uses a gearbox).&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="30468" LastEditDate="2018-05-04T04:19:40.923" LastActivityDate="2020-01-17T13:31:23.483" Title="Is it possible to drive a prop directly from a jet engine without a gearbox?" Tags="&lt;turboprop&gt;&lt;turbine&gt;" AnswerCount="3" CommentCount="12" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26103" PostTypeId="1" CreationDate="2016-03-12T20:21:31.950" Score="8" ViewCount="601" Body="&lt;p&gt;In the movie &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dr._Strangelove&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dr. Strangelove or How I Learned to Stop Worrying and Love the Bomb&lt;/a&gt;&lt;/em&gt;, a safe appears at 4:05 (you can see the sequence &lt;a href=&quot;https://www.youtube.com/watch?v=p-KIAsuoMAQ&amp;amp;index=4&amp;amp;list=PLi5kiwsTn956Vd_S4ztzMOwe2AhZoag7Z&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there really a safe on the B-52? If so, is it normal that bomber planes have a safe on board?&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="62" LastEditDate="2017-01-11T13:41:04.463" LastActivityDate="2017-01-11T13:41:04.463" Title="Is there really a safe for storing secret orders on board a B-52 bomber?" Tags="&lt;military&gt;&lt;strategic-bomber&gt;" AnswerCount="0" CommentCount="8" ClosedDate="2017-01-09T18:52:36.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="26104" PostTypeId="2" ParentId="26096" CreationDate="2016-03-12T20:58:28.737" Score="5" Body="&lt;p&gt;I did most of my training at a towered airport in Class D airspace (&lt;a href=&quot;https://skyvector.com/airport/PNE/Northeast-Philadelphia-Airport&quot; rel=&quot;nofollow&quot;&gt;KPNE&lt;/a&gt;). From my experience there is no &quot;best time&quot; (although there are times when the airspace is more empty) and for what it's worth I found it better to train when the airport was busy as it offered me the chance to practice some real world scenarios.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Running laps in the pattern when no one was around did not really build up my communication skills with the tower as they basically would just clear you for the option every time. When there were other planes in the area they might extend a leg of your pattern or have you do a 180, and these scenarios were better practice in my opinion. Crowded radio frequencies also keeps you on your toes and gets you better practice (especially if there are some similar tail numbers in the area).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will not be upsetting operations by any means. ATC is there to handle you and frankly it's always good to practice being diverted (if that's what happens) in a busy airspace so you will know how to handle it when you get out on your own missions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Class C/D space airports generally run a lot of large private traffic and some scheduled carriers. I found that KPNE and &lt;a href=&quot;https://skyvector.com/airport/ABE/Lehigh-Valley-International-Airport&quot; rel=&quot;nofollow&quot;&gt;KABE&lt;/a&gt; (if I wanted to practice in class C) were heavier later in the day and early in the morning as would be logically expected. But to be honest there were plenty of times a bunch of planes would come in all at once mid day and it would be quiet the rest of the day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are a student pilot (you did not say in your question) you can identify yourself as such when entering the airspace and when getting on with the tower. In most cases it will make them a bit more forgiving if you ask for an instruction repeat or don't understand something.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="12720" LastEditDate="2016-03-13T12:38:43.383" LastActivityDate="2016-03-13T12:38:43.383" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26105" PostTypeId="1" AcceptedAnswerId="26146" CreationDate="2016-03-12T23:36:16.340" Score="3" ViewCount="718" Body="&lt;p&gt;After passing through the packs and turbines, where does the air get into the cabin? On the 737-800, for example. I don't see on the roof any grill to let the air enter the cabin, look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/crZ7q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/crZ7q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Norwegian-Air-Shuttle/Boeing-737-8JP/2171237/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where does the air enter the cabin? According this graphic, the air enters through the roof and exits through the wall:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/H8Cvg.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/H8Cvg.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-13T00:40:42.533" LastActivityDate="2016-03-14T06:04:50.133" Title="Where does the air enter the passenger cabin?" Tags="&lt;aircraft-systems&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26106" PostTypeId="2" ParentId="26102" CreationDate="2016-03-12T23:40:24.040" Score="21" Body="&lt;p&gt;As a side comment, there is a type of engine researched in the 80's/90's, but never marketed, where an unducted fan is driven directly by the turbine shaft without a gearbox: The &lt;a href=&quot;https://en.wikipedia.org/wiki/Propfan&quot; rel=&quot;nofollow noreferrer&quot;&gt;propfan&lt;/a&gt;. It's close to your idea, albeit the unducted fan is not exactly a propeller. Safran &lt;a href=&quot;https://www.safran-group.com/media/20140102_open-rotor-engine-tomorrow-test-bench&quot; rel=&quot;nofollow noreferrer&quot;&gt;has restarted researching&lt;/a&gt; on this design, end of 2017, for an operational use after 2030.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MDtP8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MDtP8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Two counter-rotating unducted fans on a free turbine engine (&lt;a href=&quot;http://www.b-domke.de/AviationImages/Rarebird/0809.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having discarded the propfan, let's go to the actual answer!&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A propeller rotational speed doesn't exceed 1,000 or 1,500 RPM (it depends on its size too). The slowest shaft of a jet engine spins in the range of 5,000 to 15,000 RPM, sometimes more. A reduction gear is used to compensate for the difference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A fan may spin at 5,000 RPM, however the use of a reduction gear is also desirable, though it is often avoided by limiting the speed of the core, at the expense of a loss of efficiency. New aircraft like the A320 NEO can be fitted with geared turbofan engines, for better performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason the turbine cannot spin at a lower speed is that a low speed means low torque, a problem common to many air-breathing engines (maybe except the &lt;a href=&quot;https://en.wikipedia.org/wiki/Free-turbine_turboshaft&quot; rel=&quot;nofollow noreferrer&quot;&gt;free turbine&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xikne.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xikne.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Dotted line: Theoretical torque at low speed. Plain: Actual torque. You may compare with trying to pull away in a hill in fourth gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low torque also means increased spool up time, a drawbacks that is often a no-go factor.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet engines must rotate at high speeds by principle, as a lot of air must be compressed to burn a lot of fuel in a small amount of time. On the other hand the fan or the propeller are more efficient at low RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's see how engineers have dealt with these two opposite needs in different engine types.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Single-spool turbofan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simplest design is the single spool engine (all discs rotating at the same speed). While this is possible, the output shaft is at a high rotational speed. This is usable for a fan which also rotates at high speed. The core compressor is not as efficient as it could if it rotated faster.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Snecma &lt;a href=&quot;https://en.wikipedia.org/wiki/Snecma_M53&quot; rel=&quot;nofollow noreferrer&quot;&gt;M53-P2&lt;/a&gt;, used on the military jet Mirage 2000, has a rotational speed of 10,600 RPM.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Better efficiency can be achieved by increasing the compressor speed and reducing the speed of the fan. It requires the use of a distinct second spool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Two-spool turbofan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such configuration is used in many turbofans (Rolls-Royce being a notable exception with a third spool). A low-speed / low-pressure turbine drives the fan and usually the first stages of the compressor.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From this &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/EASA%20E%20004%20TCDS%20issue%2005_20160103_1.0.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA certificate&lt;/a&gt;, the CFM56-7B used on all B737 NG has a maximum HP shaft speed of about 15,000 RPM and a LP shaft speed of about 5,400 RPM.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Increased efficiency needs to further increase the fan diameter but also to slow down the fan to keep the linear speed of the tips at a reasonable value. A slower fan will not be directly driven by the turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Geared turbofan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Slowing the LP turbine adds complexity and also creates a problem: The output torque also decreases (which is a phenomena in all mechanical engines). This leads to increased reaction times after thrust requests, with also means less safe engines. A gearbox is used to prevent sacrificing the precious torque. This unusual configuration is an option on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320neo_family&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320 NEO&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW1000G&quot; rel=&quot;nofollow noreferrer&quot;&gt;PW1000G&lt;/a&gt; (formerly known as project GTF) has a HP shaft at 20,000 RPM, a LP shaft at 15,000 RPM, and the fan connected by a 3:1 reduction gearbox rotates at 5,000 RPM.&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/qcXkE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qcXkE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;planetary reduction gearbox 3:1 (&lt;a href=&quot;http://www.lavionnaire.fr/MotorTurboReact.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the altitude is sacrificed for other benefits and the engine is used in denser air, then a turbofan is not anymore an efficient solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turboprop&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the fan is replaced by a plain old propeller working at a much slower rotational speed, the use of a speed reduction gearbox with a larger ratio is a required all the more for the same reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_Dash_8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dash 8 / Q400&lt;/a&gt; which has STOL performances, is equipped with two &lt;a href=&quot;http://www.atechturbine.com/engines/pratt-whitney-canada-pw150&quot; rel=&quot;nofollow noreferrer&quot;&gt;PW150A&lt;/a&gt; turboprops. The PW150A is a two-spool core with a free power turbine (two discs not linked to the gas generation section). The &lt;a href=&quot;https://aviation.stackexchange.com/questions/14501/can-you-identify-this-jet-turbine-stage/15542#15542&quot;&gt;free turbine&lt;/a&gt; allows for better propeller speed management, allowing an engine start with the propeller stopped.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;From its &lt;a href=&quot;https://easa.europa.eu/system/files/dfu/TCDS%20PW150%20series%20issue%2001_20141119_1.0.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA certificate&lt;/a&gt;, the HP shaft runs at 31,150 RPM, the LP shaft at 27,000 and the maximum output shaft speed doesn't exceed 1,020 RPM.&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KVOuH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KVOuH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;PW150A (&lt;a href=&quot;http://media.photobucket.com/user/Aceyouroral/media/PW150A.jpg.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;Note: this schematic is not accurate, but it illustrates the principle. Look with an &lt;a href=&quot;http://www.flightrun.com/bombardier-q400/engine-pw150a&quot; rel=&quot;nofollow noreferrer&quot;&gt;accurate (but less readable) schematic&lt;/a&gt; of the engine sections.&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional experimentation: Propfan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly there is an intermediate solution between the fan and the propeller: The unducted fan. It combines the advantages of a high rotational speed and the lack of duct, the drawback being the noise generated by unducted blades close to Mach 1 airflow at the tip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Testing was conducted by several engine manufacturers but no engine was launched on the commercial market for reasons that appear to be &lt;a href=&quot;https://www.flightglobal.com/news/articles/whatever-happened-to-propfans-214520/&quot; rel=&quot;nofollow noreferrer&quot;&gt;non-technical&lt;/a&gt;. An example studied by GE and Nasa combined a double unducted fan (UDF) and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Free-turbine_turboshaft&quot; rel=&quot;nofollow noreferrer&quot;&gt;free turbine&lt;/a&gt; in a new type of engine known as &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Propfan&quot; rel=&quot;nofollow noreferrer&quot;&gt;propfan&lt;/a&gt;&lt;/em&gt;, in a pusher configuration.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://lyle.smu.edu/propulsion/Pages/Images/propfandiagram.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WVeGc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://lyle.smu.edu/propulsion/Pages/variations.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two counter-rotating fans were mounted directly on the free turbine output shaft without a gearbox.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-01-17T13:31:23.483" LastActivityDate="2020-01-17T13:31:23.483" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26107" PostTypeId="2" ParentId="12930" CreationDate="2016-03-13T00:02:53.530" Score="3" Body="&lt;p&gt;Indeed, this is a Skyvan. It was built in Belfast at the Short Brothers facility, near to the then RAF Sydenham - now George Best Airport. My father worked for Shorts as a senior design engineer. In the late 1960s I was able to visit the assembly floor. I was aged nine or ten. I saw part-completed early variant Skyvans. from time to time, I saw the finished planes over Belfast Lough as they were subjected to test flights.&lt;/p&gt;&#xA;" OwnerUserId="13985" LastActivityDate="2016-03-13T00:02:53.530" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26108" PostTypeId="2" ParentId="26102" CreationDate="2016-03-13T01:44:32.310" Score="9" Body="&lt;p&gt;You are right, it is desirable to avoid the gearbox. Big turboprop engines use a two-spool design in which the low pressure turbine is exclusively turning the propeller. However, this also needs a gearbox, albeit with a smaller gearing ratio. The gearbox has been accepted by engine designers as the lesser of two evils, the bigger evil being an excessively large turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V8v3R.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V8v3R.jpg&quot; alt=&quot;Cut-away drawing of the AE-2100 turboprop engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cut-away drawing of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_AE_2100&quot; rel=&quot;noreferrer&quot;&gt;AE-2100 turboprop engine&lt;/a&gt; (picture &lt;a href=&quot;https://myaeroengine.com/OnWingCare/IMAGES/AE_2100A_cutaway.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). The turbine has four stages, the first two driving the high-speed spool and the 14-stage compressor, while the inner, low-speed spool is driven by the last two turbine stages and is connected to the gearbox in front. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the turbine would spin slowly enough to avoid a gearbox altogether, it would need to be much bigger. This would result in an undesirably large nacelle, causing an equally undesirable drag increase. Also, the larger, slower-spinning turbine will make the whole engine much heavier, not simply because the turbine wheel is larger, but mostly because the engine casing has to become much larger, too. Note in the cut-away picture of the AE-2100 above that the low speed turbine is already the widest component - making it any wider would increase drag and engine mass significantly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotational speed of the turbine easily doubles or triples the flow speed at the turbine blade, thus increasing the dynamic pressure at the blade by a factor between four and nine over the dynamic pressure of the axial flow at the exit area of the high speed turbine. A slower turbine would work at a much lower dynamic pressure and will need an increased radius to still give the same torque, which is the product of blade lift and radius. Only the increased number of blades and the increased radius of a much bigger turbine will compensate for the much lower dynamic pressure at the turbine blades.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-13T10:19:04.347" LastActivityDate="2016-03-13T10:19:04.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26109" PostTypeId="5" CreationDate="2016-03-13T02:03:08.110" Score="0" Body="&lt;p&gt;Aircraft windows are much like any other windows - a piece of glass or plastic used to see outside. Some aircraft windows also serve as part of the pressurization vessel.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="1961" LastEditDate="2016-03-13T02:20:07.770" LastActivityDate="2016-03-13T02:20:07.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26110" PostTypeId="4" CreationDate="2016-03-13T02:03:08.110" Score="0" Body="Used for questions pertaining to aircraft windows." OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-13T02:20:42.770" LastActivityDate="2016-03-13T02:20:42.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26111" PostTypeId="5" CreationDate="2016-03-13T02:04:16.833" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-03-13T02:04:16.833" LastActivityDate="2016-03-13T02:04:16.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26112" PostTypeId="4" CreationDate="2016-03-13T02:04:16.833" Score="0" Body="For questions about pilots who fly for airlines." OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-13T02:20:35.943" LastActivityDate="2016-03-13T02:20:35.943" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26113" PostTypeId="2" ParentId="26091" CreationDate="2016-03-13T02:12:03.017" Score="18" Body="&lt;p&gt;On the 747-8 the engines are heavier and mounted farther ahead of the wing. This results in a torsion moment which reduces the incidence of the wing. As a result, even the unloaded wing will have a lower incidence than that of the older 747-200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8w6N3.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8w6N3.jpg&quot; alt=&quot;Transaero Boeing 747-346&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-346 of Transaero (picture &lt;a href=&quot;http://www.airplane-pictures.net/photo/105968/vp-bgu-transaero-airlines-boeing-747-300/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Note that the engines are no longer tilted up (and consequently the wing tip is tilted leading edge down). The lift force twists the wing such that the incidence in flight is lower than when unloaded and on the ground, especially when the high-lift devices are extended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also please make sure to read @Lilibete's answer. I don't know who thought it appropriate to downvote it - it contains another reason for the change in inlet angles, namely the difference in avoidance strategies for foreign object damage.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2017-09-23T00:02:11.563" LastActivityDate="2017-09-23T00:02:11.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26114" PostTypeId="2" ParentId="26101" CreationDate="2016-03-13T02:36:32.337" Score="12" Body="&lt;p&gt;For the same reason why the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;noreferrer&quot;&gt;Lockheed F-104 Starfighter&lt;/a&gt; had such a pronounced anhedral: It is the size and location of the vertical tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wQ5hQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wQ5hQ.jpg&quot; alt=&quot;Lockheed F-104 Starfighter&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed F-104 Starfighter (picture &lt;a href=&quot;http://www.yellowairplane.com/Museums/images/F-104_Starfighter_Afterburners_Lit.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both cases, the vertical tail is large relative to the wing and fully above the roll axis. In a sideslip it produces a high rolling moment, so any more rolling moment from the wing would reduce the handling qualities of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially in case of the F-104, the raised position of the horizontal tail shifts the center of pressure on the vertical tail upwards, exacerbating the offset location of the vertical tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rear-mounted engines on the Falcon 900 move the center of gravity backwards, so the wing is more backwards than usual for aircraft with wing-mounted engines. Therefore, the part of the fuselage ahead of the center of gravity is large, requiring a larger vertical tail to overcome the destabilizing yawing moment of the fuselage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-134&quot; rel=&quot;noreferrer&quot;&gt;Tupolev 134&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-154&quot; rel=&quot;noreferrer&quot;&gt;154&lt;/a&gt;, and - surprise! - they also have no dihedral, even though both are low-wing configurations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/22130.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/22130.jpg&quot; alt=&quot;Tupolev 154M of the Polish Air Force&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev 154M of the Polish Air Force (picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Polish_Air_Force_Tupolev_Tu-154M_Lebeda.jpg/800px-Polish_Air_Force_Tupolev_Tu-154M_Lebeda.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-13T02:36:32.337" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26115" PostTypeId="1" AcceptedAnswerId="26116" CreationDate="2016-03-13T03:36:08.357" Score="20" ViewCount="4563" Body="&lt;p&gt;I'm story-boarding a novel. I'm toying with the idea of contriving a situation in which a midsize commercial aircraft is forced to make an emergency landing on an aircraft carrier. I read &lt;a href=&quot;http://theaviationist.com/2014/07/16/c-130-land-on-carrier/&quot;&gt;here&lt;/a&gt; that the largest plane to land on an aircraft carrier is a C130 Hercules, which it did as a series of tests. Its maximum weight when performing these tests was 121,000 lbs. At this weight, it required only 460 feet to land. And it did so without use of a tailhook, or any other arresting mechanism. The brand new Gerald R. Ford class carrier is 1,106 feet long. The landing strip on the carrier is somewhat shorter. I couldn't find numbers on this, but from photos, I would estimate that the landing strip is a little more than 800 feet long. Which leads me to my first question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In an emergency situation, could an aircraft use the full length of the aircraft carrier's deck to land?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the answer to the above is yes, this means that our commercial aircraft has somewhat more than twice the distance to make its landing than the C130 did. Let us assume that the commercial aircraft is a B737 Classic, weighing aobut 140,000 pounds, just a little more than the C130 did during the tests. This leads me to my main question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Could a 737 Classic safely make an unarrested emergency landing on a Gerald R. Ford Class aircraft carrier?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By safely, I mean without any passenger death. I expect that any such landing attempt would result in significant damage to the aircraft and the carrier. On one hand, the numbers seem to suggest that if a C130 can do it, so could a B737. On the other hand, I would expect that the C130, as a military aircraft, is more robust than a commercial aircraft, and perhaps able to better meet the conditions required to land on a carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I realize that in an emergency situation it may be safer for the aircraft to make a water landing near the carrier, and then for the passengers to evacuate onto inflatable rafts, finally to be brought aboard shortly thereafter. I will have to invent a situation which requires the plane to land on the carrier.&lt;/p&gt;&#xA;" OwnerUserId="13988" LastEditorUserId="12220" LastEditDate="2016-03-13T14:57:11.037" LastActivityDate="2020-09-16T12:48:53.883" Title="Is is possible to land a midsize commercial plane on an Ford Class aircraft carrier?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;aircraft-carrier&gt;" AnswerCount="4" CommentCount="15" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26116" PostTypeId="2" ParentId="26115" CreationDate="2016-03-13T04:31:37.640" Score="31" Body="&lt;p&gt;A Classic 737's &lt;strong&gt;maximum&lt;/strong&gt; landing weight is about 114,000# for a -300, less for a -500, more for a -400.  But that is max. Down to &amp;quot;almost empty&amp;quot; gas tanks, knock another 8 or 10,000# off of that. Less than full pax/cargo load, several more thousand pounds off.&lt;/p&gt;&#xA;&lt;p&gt;With a stiff breeze, say 20 knots, plus the carrier at max speed, you have maybe 50 knots of headwind. With that sort of headwind, can you stop a mid- to light-weight 737 in 1000' using full flaps, max reverse, and max brakes?&lt;/p&gt;&#xA;&lt;p&gt;I don't have the charts with me, but I suspect you totally could, and in fact it wouldn't even be all that close. No margin for error if equipment fails, but if everything works right, those jets can stop quite well. And 50 knots on the beak is a LOT of headwind... &amp;quot;groundspeed&amp;quot; over the deck would be like 60 or 70 knots, and you can lose that in a lot less than 1000'.&lt;/p&gt;&#xA;&lt;p&gt;I've flown C-130's and 737's, and the rate of descent on an assault landing in the Herk is nothing the 737 couldn't handle.&lt;/p&gt;&#xA;&lt;p&gt;So... carrier landing... good to go?&lt;/p&gt;&#xA;&lt;p&gt;Not so sure.  Compared to carrier aircraft, the 737 wingspan in WIDE -- even for the &amp;quot;little&amp;quot; -500.  That limits where you can plan your rollout so that you don't have an unacceptably high risk of clipping the island. Without playing with scale drawings of a 737 and the Ford's deck, I couldn't even guess if or how the geometry would or wouldn't work out.&lt;/p&gt;&#xA;&lt;p&gt;Alternate plan that is probably no more risky for the passengers and might be a LOT safer for the carrier: ditch your (nearly out of fuel) jet close to the carrier, and have the carrier's helos and the small boats of the battle group pull the survivors off the wings or out of the water. With calm water, you get a &amp;quot;Sully&amp;quot; scenario (except with wings filled mostly with air, rather than jet fuel... Better buoyancy). In rough water, the risks go up. Way up.&lt;/p&gt;&#xA;&lt;p&gt;But in that sort of weather, the deck landing gets lots more risky as well.&lt;/p&gt;&#xA;&lt;p&gt;I suspect the deck landing would neither be allowed nor requested, but not for reasons of stopping performance.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2020-09-16T12:48:53.883" LastActivityDate="2020-09-16T12:48:53.883" CommentCount="12" ContentLicense="CC BY-SA 4.0" />
  <row Id="26117" PostTypeId="2" ParentId="26096" CreationDate="2016-03-13T05:53:27.147" Score="3" Body="&lt;p&gt;I did all my training in the NYC area from airports with towers. KMMU and KCDW. There was no such thing as a good time (other than 2am to 5 am). For my first solo, I was number 14 to land. Both of those airports share the same approach control frequency as KEWR. If you want to do an approach, you had to do it in traffic. You'd be the only person doing the LOC or ILS at KMMU/KCDW but you'd be sharing the frequency with non-stop approaches to KEWR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd suggest getting some training with an instructor at a busy airport with a tower.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-03-13T05:53:27.147" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26118" PostTypeId="1" AcceptedAnswerId="26134" CreationDate="2016-03-13T07:59:02.260" Score="16" ViewCount="1786" Body="&lt;p&gt;In most POHs, the flap configuration for short-field is usually recommended as partial flaps, for instance 10˚ for C172. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember the arguments are that full flaps would reduce the acceleration rate, and in no flaps the airplane would have to accelerate to higher speed to off the ground. In either case, the ground roll distance is longer than the optimal partial-flap configurations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this assumes a fixed flap setting during ground roll. How about let the airplane accelerate to a certain speed (in zero flaps) before adding to full flaps? We could achieve best acceleration as well as best lift-off speed?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="595" LastEditDate="2016-03-13T12:37:29.083" LastActivityDate="2016-03-16T01:26:59.663" Title="Does adding flaps during ground roll perform better in short-field takeoff?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;pilot-technique&gt;&lt;maneuver&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26119" PostTypeId="1" AcceptedAnswerId="26120" CreationDate="2016-03-13T09:35:46.797" Score="20" ViewCount="4717" Body="&lt;p&gt;On some instrument approaches, the autopilot-coupled approach is not authorized (or not authorized below a certain minimum). &#xA;For example, &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Autopilot-coupled NA (&lt;a href=&quot;http://flightaware.com/resources/airport/MRY/IAP/ILS+OR+LOC+RWY+10R/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;MRY: ILS OR LOC RWY 10R&lt;/a&gt;)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zUv98.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zUv98.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Autopilot-coupled NA below a minimum (&lt;a href=&quot;http://flightaware.com/resources/airport/LVK/IAP/ILS+RWY+25R/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;LVK: ILS RWY 25R&lt;/a&gt;)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1gsCk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1gsCk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Moreover, on some approaches, the DA is lower if we have a AP/FD/HUD. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess the lower DA is because we can give more attention outside the window when there is AP/FD/HUD's assistance. I didn't come up with any idea or context why autopilot-coupling won't work. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is turbulent and the autopilot doesn't respond quickly enough to keep the needle centre, we may not use autopilot at all. If the air is calm, the autopilot may well outperform hand-flying. However, it depends on the quality of the autopilot.  &lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2019-11-22T08:44:56.470" LastActivityDate="2019-11-22T08:44:56.470" Title="What are the reasons for autopilot restrictions on instrument approaches?" Tags="&lt;instrument-flight-rules&gt;&lt;autopilot&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26120" PostTypeId="2" ParentId="26119" CreationDate="2016-03-13T12:04:42.863" Score="23" Body="&lt;p&gt;It's the fact the autopilot works more accurately than a pilot which is actually the cause of the restriction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The decision to restrict the use of the autopilot usually comes from the certification agency after the ILS inspection flight detected glideslope erratic variations or reversals. The false signals are likely due to interference from the environment or the nearby activities with the runway equipment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight inspection volume&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ILS volume surveyed by certification agencies using ICAO recommendations is located below a 5.25° angle. It means G/S indications are checked and expected to be correct only below this angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Bum3f.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bum3f.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://www.isasi.org/Documents/ISASI%202014%20-%20Beumkes%20Schuurman%20-%20Dutch%20Safety%20Board%20-%20Glide%20slope.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is why G/S are usually intercepted &lt;em&gt;from below&lt;/em&gt; unless specific procedures are in place and extra care is given to validate G/S indications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Anomalies in flight inspection volume&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However there can be false and reversed guidance areas within this volume. They are discovered when the ILS is commissioned and flight tested by the certification agency. Example of glideslope reversal during an inspection on the nominal slope:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/v2Tru.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/v2Tru.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/avn/flightinspection/onlineinformation/pdf/TI%208200-52%20w%20Chg%201-%204.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;, page 15-97)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these areas, the ILS signal may vary quickly and if the autopilot were active it could react to the variations, while a pilot will likely not notice the interference, or will disregard it unless it follows a trend for a few seconds. A pilot with a Vertical Situation Display can confirm the ILS error visually.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A reversal, which is a guidance given in the wrong direction, can lead to a serious incident or an accident, due to autopilot quick reaction time. When such reversals are discovered during the inspection flight, autopilot approaches are not authorized, or forbidden during the final segment where the consequences can be the worst.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Consequences of a reversal during autopilot approach&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using the erroneous signal from the ILS may divert the aircraft from the approach path. Being below the glideslope close to the threshold is indeed not desirable, especially for a jet aircraft for which the thrust increase required to recover the lost altitude cannot be obtained instantaneously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suddenly jumping higher is also dangerous. It leads to a loss of airspeed, and possibly to an unrecoverable stall. Below is an example of autopilot reaction to a reversal. While it didn't happen in the certified volume of the ILS, the principle is exactly the one found in any reversal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Some explanation about the context it happened&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was believed for a long time ILS radio signals for the glideslope contain false guidance at angles multiple of the nominal approach slope (e.g. 6° and 9° for a 3° G/S), but it was also taken for certain these false glideslopes were not reversals and would anyway guide the aircraft to the threshold, at a different descent rate (which would be enough to warn the crew about them following a wrong glide angle).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However G/S reversals, especially after 9° has been observed later (2011-2013), for some types of ILS antennas, without a full understanding of the reasons. Among these cases (source &lt;a href=&quot;https://www.icao.int/NACC/Documents/Meetings/2015/PARAST21/PA-RAST21SummaryDiscussions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Schiphol Airport, The Netherlands, 2011, KLM, Embraer E190&lt;/li&gt;&#xA;&lt;li&gt;Murcia Airport, Spain, 2011, Ryanair, Boeing 737-800&lt;/li&gt;&#xA;&lt;li&gt;Charles de Gaulle Airport, France, 2012, Air France, A340 (&lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/2466.pdf/A343,_vicinity_Paris_CDG_France,_2012&quot; rel=&quot;nofollow noreferrer&quot;&gt;BEA report&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;Treviso Airport, Italy, 2013, Ryanair, Boeing 737-800&lt;/li&gt;&#xA;&lt;li&gt;Eindhoven Airport, Netherlands, 2013, Ryanair, Boeing 737-800.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Eindhoven serious incident, May 2013&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A B738 on autopilot was flying a non stabilized approach where the G/S had been captured from above. When reaching the 9° glideslope area, at 0.85 NM from the threshold, the aircraft suddenly pitched up to 24° and climbed from 400 to 1,000 ft. Airspeed plummeted to 100 kt, the stick shaker activated:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MXjCO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MXjCO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;https://www.skybrary.aero/index.php/B738,_vicinity_Eindhoven_Netherlands,_2013&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;. Original source: Dutch Safety Board &lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/3452.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;report&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the investigation done by the Dutch agency, it appears the actual guidance provided around 6° and 9° is completely reversed:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CbijJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CbijJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.anac.gov.br/assuntos/paginas-tematicas/gerenciamento-da-seguranca-operacional/use-of-reactive-information-to-enhance-pa-rast-safety.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a partial mitigation measure, Boeing changed the Flight Control Computer software to limit the pitch up rate in G/S mode. The BEA also recommended manufacturers would prevent the capture of the G/S by an aircraft not on the published glidepath.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-10-24T19:18:49.200" LastActivityDate="2019-10-24T19:18:49.200" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="26121" PostTypeId="1" AcceptedAnswerId="26123" CreationDate="2016-03-13T12:32:59.860" Score="8" ViewCount="1204" Body="&lt;p&gt;I recently saw a picture of a Russian Bear(TU-95) intercepting one of our(US) military aircraft over the Pacific Ocean.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many years ago, when I flew in reconnaissance aircraft, we were frequently intercepted by Bears which surprisingly flew at 500+ mph airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet no US Military Aircraft uses contra-rotating props(to my knowledge).&#xA;Why is that?&lt;/p&gt;&#xA;" OwnerUserId="3671" LastEditorUserId="12220" LastEditDate="2016-03-13T12:55:36.470" LastActivityDate="2017-11-09T19:11:24.640" Title="Has the United States Air Force used Contra-rotating Propeller Aircraft?" Tags="&lt;military&gt;&lt;propeller&gt;&lt;us-air-force&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26122" PostTypeId="2" ParentId="24715" CreationDate="2016-03-13T13:08:03.630" Score="10" Body="&lt;p&gt;Assuming you are asking about civilian flights operated under FAA rules, part 91 rules (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.3.7.3&quot; rel=&quot;noreferrer&quot;&gt;14 CFR §91.205(b)(12)&lt;/a&gt;) advise that approved and serviceable flotation devices are required to be carried for each occupant during flight where such flight takes place over water outside power-off gliding distance to shore. &amp;quot;Shore&amp;quot; has a specific definition.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;If the aircraft is operated [for VFR flight during the day] for hire over water and beyond power-off gliding distance from shore, [it must carry] approved [and serviceable] flotation gear readily available to each occupant and, unless the aircraft is operating under part 121 of this subchapter, at least one pyrotechnic signaling device. As used in this section, “shore” means that area of the land adjacent to the water which is above the high water mark and excludes land areas which are intermittently under water.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;These provisions are extended to VFR flight at night and IFR flight in 14 CFR §91.205(c) &lt;em&gt;et seq.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Part 91 subpart F stipulates the requirements for large/turbine-powered multiengine operations (where such rules exclude flights for the purposes of common carriage). In summary, §91.509 requires approved flotation devices when operated more than 50 miles from the nearest shore, and liferafts, survival kits, etc for flights operated more than 30 minutes flying time or more than 100 nautical miles from the nearest shore.&lt;/p&gt;&#xA;&lt;p&gt;Most &amp;quot;commercial&amp;quot; flights in large aircraft are further regulated in terms of equipment by sections under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f52c531cb9666e6a5f41c1db362fa09c&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1339&quot; rel=&quot;noreferrer&quot;&gt;part 121&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f52c531cb9666e6a5f41c1db362fa09c&amp;amp;mc=true&amp;amp;node=pt14.3.125&amp;amp;rgn=div5#se14.3.125_1209&quot; rel=&quot;noreferrer&quot;&gt;part 125&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f52c531cb9666e6a5f41c1db362fa09c&amp;amp;mc=true&amp;amp;node=pt14.3.135&amp;amp;rgn=div5#se14.3.135_1167&quot; rel=&quot;noreferrer&quot;&gt;part 135&lt;/a&gt;, etc. with similar equipment requirements to those noted above (links take you directly to relevant sections of the code for extended overwater operations under each part).&lt;/p&gt;&#xA;&lt;p&gt;If operating a commercial air tour compliant with part 136, and such tour is to take place over water beyond minimum gliding distance in a non-compliant aircraft except for the purposes of takeoff and landing, then the code in 14 CFR §136.9 is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=f52c531cb9666e6a5f41c1db362fa09c&amp;amp;mc=true&amp;amp;node=pt14.3.136&amp;amp;rgn=div5#se14.3.136_19&quot; rel=&quot;noreferrer&quot;&gt;more strict&lt;/a&gt;: occupants must wear life jackets until at least the period when the flight ceases to be over water.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Except as provided in paragraphs (b) or (c) of this section, the operator and pilot in command of commercial air tours over water beyond the shoreline must ensure that each occupant is wearing a life preserver from before takeoff until flight is no longer over water.&lt;/p&gt;&#xA;&lt;p&gt;(b) The operator and pilot in command of a commercial air tour over water beyond the shoreline must ensure that a life preserver is readily available for its intended use and easily accessible to each occupant if:&lt;/p&gt;&#xA;&lt;p&gt;(1) The aircraft is equipped with floats; or&lt;/p&gt;&#xA;&lt;p&gt;(2) The airplane is within power-off gliding distance to the shoreline for the duration of the time that the flight is over water.&lt;/p&gt;&#xA;&lt;p&gt;(3) The aircraft is a multi engine that can be operated with the critical engine inoperative at a weight that will allow it to climb, at least 50 feet a minute, at an altitude of 1,000 feet above the surface, as provided in the Airplane Flight Manual or the Rotorcraft Flight Manual, as appropriate.&lt;/p&gt;&#xA;&lt;p&gt;(c) No life preserver is required if the overwater operation is necessary only for takeoff or landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In summary, for FAA aircraft operating solely over land, the regulations noted above and by Ralph J's &lt;a href=&quot;https://aviation.stackexchange.com/questions/24715/are-life-jackets-mandatory-on-planes-that-will-never-fly-over-water-bodies#comment57937_24715&quot;&gt;comment&lt;/a&gt; proscribe that the required equipment to be carried is minimal.&lt;/p&gt;&#xA;&lt;p&gt;Of course, what the letter of the law says, and what's a good idea to carry, may in some cases be different things -- I'm thinking here about good practice to carry additional life preserving equipment when operating a GA aircraft for an extended time over water.&lt;/p&gt;&#xA;" OwnerUserId="2032" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-14T16:17:44.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26123" PostTypeId="2" ParentId="26121" CreationDate="2016-03-13T13:54:35.017" Score="12" Body="&lt;p&gt;In short, the US didn't need one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason for the development of &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-95?wprov=sfla1&quot;&gt;Tu-95&lt;/a&gt; was the rather unique situation existing after WWII, when the Soviet Union needed a heavy bomber to carry the (then very heavy) nuclear weapons. Due to the lack of bases anywhere near contiguous United States, the Soviets were at a significant disadvantage when it came to nuking the US before the ICBMs came into picture (US had bases in Europe and in Pacific). At that time, heavy bombers were the only way to deliver a nuclear payload and it required the aircraft to be fast, have a intercontinental range and be able to carry a reasonable payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first attempt in developing a long range bomber during the last days of WWII by the Soviets didn't work out and as a result, they simply reverse engineered USAAF B-29s which had 'landed' in Russia into the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-4&quot;&gt;Tu-4 'Bull'&lt;/a&gt;, which lacked the necessary range. In a way, the B-29 was the forefather of Tu-95. Further development continued on this airframe, culminating in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-85&quot;&gt;Tu-80 'Barge'&lt;/a&gt;, which had the necessary range, but was considered unsuitable as it lacked speed, which would be fatal against jet interceptors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Tu-95 was developed at the same time of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_B-52_Stratofortress&quot;&gt;B-52 'stratofortress'&lt;/a&gt;. Actually the Soviet Air Force preferred the jet powered &lt;a href=&quot;https://en.wikipedia.org/wiki/Myasishchev_M-4&quot;&gt;Myasishchev M-4&lt;/a&gt; and Tupolev had to convince Stalin about the Tu-95's suitability. During the initial design phase, the Tupolev bureau considered two versions- one with four turbojets and another one with turboprops. The turbojet version was discarded as it would've lacked range due to the fuel hungry turbojets (Tupolev turned out to be right about that as the M-4 was sidelined due to lack of range).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The payload and speed requirements required a very powerful engine (the &lt;a href=&quot;https://en.wikipedia.org/wiki/Kuznetsov_NK-12&quot;&gt;Kuznetsov NK-12&lt;/a&gt; is the most powerful turboshaft engine ever) and the contra-rotating props were selected to overcome the problems associated with the large diameter of the propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Western countries also did a lot work with contra-rotating props, but the advent of jet engines and the complexites associated with the counter-rotating props meant few graduated from the prototype stage. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Hughes_XF-11&quot;&gt;Huges XF-11&lt;/a&gt;, for example had counter rotating props initially; they were changed to conventional ones after Huges crashed in it. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Fairey_Gannet&quot;&gt;Fairey Gannet&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Avro_Shackleton&quot;&gt;Avro Shackleton&lt;/a&gt; were among the few western contra-rotating aircraft to see regular service (both were used in ASw roles, which highlight the increased endurance offered by them). A number of contra-rotating aircraft were tested during the end of WWII, but the advent of jet engines meant that the required speed could be achieved in a far better way.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="8730" LastEditDate="2016-03-14T04:39:43.880" LastActivityDate="2016-03-14T04:39:43.880" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26124" PostTypeId="1" CreationDate="2016-03-13T15:05:14.390" Score="6" ViewCount="401" Body="&lt;p&gt;I am an IFR rated pilot flying 172s and 182s out of &lt;a href=&quot;http://www.airnav.com/airport/KHHR&quot; rel=&quot;nofollow noreferrer&quot;&gt;Hawthorne Municipal Airport (KHHR)&lt;/a&gt; in Los Angeles. I've heard from other pilots that in actual IFR conditions (IMC) it can be difficult to get sequenced for an approach due to the proximity of inbound jet traffic at nearby &lt;a href=&quot;http://www.airnav.com/airport/KLAX&quot; rel=&quot;nofollow noreferrer&quot;&gt;LAX&lt;/a&gt;, perhaps due to separation requirements for IFR aircraft combined with the parallel approaches or the two airports:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ikOJ7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ikOJ7.png&quot; alt=&quot;KLAX-KHHR proximity&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What really happens when both airports are landing to the west as is most often the case? My worry is that if I'm returning home on a cloudy day, I might be forced to land at &lt;a href=&quot;http://www.airnav.com/airport/KTOA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Torrance airport (KTOA)&lt;/a&gt; and then Uber it back to my car at Hawthorne. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard from other pilots that they have returned to the area and been told they will have to hold for hours, which obviously makes the Hawthorne LOC approach useless in a practical sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, this question would be best answered by someone who works as an approach controller in the LA basin.&lt;/p&gt;&#xA;" OwnerUserId="13992" LastEditorUserId="62" LastEditDate="2016-08-09T12:13:28.173" LastActivityDate="2016-08-09T12:13:28.173" Title="Is it practical to fly IFR into Hawthorne Airport (KHHR) in IMC?" Tags="&lt;instrument-flight-rules&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26126" PostTypeId="2" ParentId="26124" CreationDate="2016-03-13T16:02:05.200" Score="5" Body="&lt;p&gt;Without pulling up the SOP/LoAs between HHR and LAX and SoCal Tracon, or working at those facilities to see if there's a better option, and just looking at the positions of the airports and their approaches, I'd say for an actual approach into HHR, you'd have to be vectored into the LAX arrival stream and sequenced like that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the approach plates, at the HHR Final approach fix you might have enough separation from LAX's 25L/R, vertically, but once you get to the end of the runway there isn't enough separation between the procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now if HHR tower can see the LAX traffic and apply visual separation that can change things as well, such that they are making sure you don't get too close, to the other final, as long as wake turbulence isn't involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond the theoretical, just call the tower or SoCal Tracon and ask, or schedule a visit and ask.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-03-13T16:02:05.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26127" PostTypeId="1" CreationDate="2016-03-13T16:48:58.520" Score="3" ViewCount="4266" Body="&lt;p&gt;To quote &lt;a href=&quot;https://www.youtube.com/watch?v=8GObJtQOUJ4&quot; rel=&quot;nofollow noreferrer&quot;&gt;John Oliver&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;&quot;Yemen, home to 26 million Yemeni people, and 27 million American drones.&quot;&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;While these numbers may be slightly exaggerated I started to wonder. As far as I know, military drones are used primarily for survaillance, meaning that they circle a potential target for hours on end to gather intelligence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I immediately thought, that they would be spotted quickly, and any illegal activity would cease. Since they seem to be effective though, this can't really be true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: Given typical operational parameters during survaillance, can military drones, like the Predator, be spotted with the naked eye if they are circling above you?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I tried to find an answer with some quick calculations of my own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can see quite a lot of airliners flying above me, and I can see their bodies quite easily. Airliners are larger though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some sizes I could gather are:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A320&lt;/strong&gt; &lt;a href=&quot;https://de.wikipedia.org/wiki/Airbus-A320-Familie&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Length: 37.57m&#xA;Wingspan: 34.1m&#xA;Body width: 3.96m&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Predator Drone&lt;/strong&gt; &lt;a href=&quot;https://de.wikipedia.org/wiki/Northrop_Grumman_RQ-4&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Length: 8.23m&#xA;Wingspan: 14.84m&#xA;Body width: 0.83m (estimated from picture)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;When I look at just the length of the aircraft, I can calculate the angular size of the object in the sky if I know the altitude. I assume the A320 flies at around 32000 feet, or 9753m. For the drone I have no idea. But it can fly at 7620m and I would assume it stays a bit below, so I assume 6000m.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vx1Om.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vx1Om.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angle of the object is then:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Angle = ArcTan(Length/Altitude)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The human eye has a resolution of &lt;a href=&quot;https://de.wikipedia.org/wiki/Aufl%C3%B6sungsverm%C3%B6gen&quot; rel=&quot;nofollow noreferrer&quot;&gt;0.5-1 arc minutes&lt;/a&gt;, or 0.0125°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the given aircraft I come to these values:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A320:&#xA;Angle = Atan(37.57/9753) = 0.22°&#xA;&#xA;Predator:&#xA;Angle = Atan(8.23/6000) = 0.08°&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;So from the length, both aircraft should be visible. However, that doesn't seem to make sense, because they need to be wide enough as well. So for the body width's I get:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;A320:&#xA;Angle = Atan(3.96/9753) = 0.024°&#xA;&#xA;Predator:&#xA;Angle = Atan(0.83/6000) = 0.008°&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;So the A320 should be visible quite comfortably, while the drone should be invisible to the naked eye.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;But&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is all theoretical. I don't know the operation of the predator, especially how high it flies. I also don't know what really determines visibility. Does the wingspan alter the numbers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone share any actual insight?&lt;/p&gt;&#xA;" OwnerUserId="7873" LastActivityDate="2016-03-13T16:48:58.520" Title="Can I spot the drones watching me in the sky with naked eyes?" Tags="&lt;unmanned-aerial-vehicle&gt;&lt;visibility&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2016-03-13T18:55:51.077" ContentLicense="CC BY-SA 3.0" />
  <row Id="26128" PostTypeId="2" ParentId="26115" CreationDate="2016-03-13T19:34:44.900" Score="3" Body="&lt;p&gt;B737-500 required landing runway requirement is around 975m, while 300/400 model needs longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although actual landing runway requirement is 3/5 of required landing runway requirement(dry) (FAA standard), Ford Class does not have such a long runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without modification of b737, it is not likely for a b737 to land on a Ford class carrier.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/xk8l4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xk8l4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On the other hand, Boeing had proposal to develop &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_T-43&quot; rel=&quot;nofollow noreferrer&quot;&gt;T-43&lt;/a&gt; Carrier Onboard Delivery. If Boeing won the USN contract, we may see B737-200 landing on aircraft carrier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More details can be seen &lt;a href=&quot;http://www.airlinereporter.com/2014/05/airliners-landing-aircraft-carrier-oh-yes/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/fVamL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fVamL.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="8000" LastEditDate="2016-03-13T23:00:07.447" LastActivityDate="2016-03-13T23:00:07.447" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26129" PostTypeId="2" ParentId="26050" CreationDate="2016-03-13T20:02:57.330" Score="0" Body="&lt;p&gt;In the equation $W=L=\frac{1}{2}\cdot\rho\cdot V_{stall}^2\cdot S\cdot C_{L,max}$ the goal is to find minimum flight speed which can produce lift equal to weight. This speed varies in different configuration but the minimum would be at maximum angle of attack producing $C_{L,max}$ (lift coefficient). The lift coefficient is a function of angle of attack, airfoil and wing geometry. &lt;/p&gt;&#xA;" OwnerUserId="13998" LastActivityDate="2016-03-13T20:02:57.330" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26131" PostTypeId="2" ParentId="26118" CreationDate="2016-03-13T20:36:33.087" Score="5" Body="&lt;p&gt;Flaps have the dual function of increasing lift and drag. When they are fully extended, the drag greatly outweighs the extra lift. So whilst you might have a slightly shortened takeoff run (though I doubt that there is a significant reduction in a C172), you could very well struggle to clear any obstacles. And not forgetting that the takeoff distance required is defined as the distance to climb to 50ft, climbing out on full flaps could actually increase this distance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might be tempted to say you should extend the flaps just in time to rotate, then retract them immediately once airborne. Retracting flaps at such a low speed and altitude is incredibly risky. Plus this is a lot of extra work for the pilot at an already critical phase of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most aircraft, using the smaller flap setting provides extra lift with only a bit of the drag. Always follow the POH - it's written by the folks who know the aircraft and its performance better than anyone. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-03-13T20:36:33.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26132" PostTypeId="1" AcceptedAnswerId="26136" CreationDate="2016-03-13T22:42:00.637" Score="23" ViewCount="26276" Body="&lt;p&gt;How long does it take to refuel a big jumbo jet? What about a smaller A320?&lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="31425" LastEditDate="2020-09-13T21:09:12.140" LastActivityDate="2020-09-13T21:09:12.140" Title="How long does it take to refuel a big jumbo jet?" Tags="&lt;airline-operations&gt;&lt;ground-operations&gt;&lt;refueling&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 4.0" />
  <row Id="26134" PostTypeId="2" ParentId="26118" CreationDate="2016-03-13T22:50:37.247" Score="8" Body="&lt;p&gt;I found this answer is a good analysis.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.av8n.com/how/htm/takeoff.html#sec-flap-popping&quot; rel=&quot;noreferrer&quot;&gt;13.3 - Obstructed-Field - Skimming versus Wheelbarrowing or Flap-Popping&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;&lt;em&gt;Another possible procedure (which is usually not recommended) is to keep the flaps retracted until you are ready to leave the runway. Less flaps means less incidence. A big disadvantage is that “popping” the flaps like this increases your workload at a time when there are lots of other things you should be attending to. Another disadvantage is that you run the risk of extending the flaps past the takeoff position to the landing position, creating lots of drag, which is really not what you want in this situation. If your POH calls for this procedure, go ahead, but be careful. Make sure you have some sort of detent to block inadvertent over-extension.&lt;/em&gt;&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;-- &lt;a href=&quot;http://www.av8n.com/how/&quot; rel=&quot;noreferrer&quot;&gt;John S. Denker, See How It Flies&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-16T01:26:59.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26135" PostTypeId="2" ParentId="26132" CreationDate="2016-03-13T23:00:53.497" Score="1" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.latedeparture.com/2011/11/30/airport-day-refuelling-planes/&quot; rel=&quot;nofollow&quot;&gt;this &lt;/a&gt;article, it generally takes about 1-2 hours to fuel a large jumbo such as an A380. As for smaller jets, the &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20061018151916AAMkss8&quot; rel=&quot;nofollow&quot;&gt;second &lt;/a&gt;answer to the Yahoo! question says that Southwest Airlines claims to be able to turn a plane around in 20 minutes. Given that the Southwest fleet is made up entirely of 737s, a jet such as the 737 or A320 should take about 15-20 minutes to refuel.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-03-13T23:00:53.497" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26136" PostTypeId="2" ParentId="26132" CreationDate="2016-03-13T23:27:43.273" Score="28" Body="&lt;p&gt;It depends on a number of factors like:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;the aircraft size and variant&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the range required&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;the aircraft load&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;equipment available&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ground crew proficiency&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;...among others things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This figure from the 737 Airport Planning document gives 9 minutes for the fueling time for a Boeing 737-600:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AwkOw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AwkOw.jpg&quot; alt=&quot;B737-600&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/737.pdf&quot; rel=&quot;noreferrer&quot;&gt;B737 Airplane characteristics for Airport Planning&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following image shows the time taken for refueling a Boeing 747-8 Jumbo to be 44 minutes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8sGiC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8sGiC.jpg&quot; alt=&quot;747-8&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_8.pdf&quot; rel=&quot;noreferrer&quot;&gt;B747-8 Airplane Characteristics for Airport Planning&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3386" LastEditDate="2016-03-14T15:55:44.947" LastActivityDate="2016-03-14T15:55:44.947" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26137" PostTypeId="2" ParentId="26132" CreationDate="2016-03-14T01:00:59.093" Score="14" Body="&lt;p&gt;It depends on how many equipment are being used to refuel and how much fuel an aircraft needs. But in general there are some ratings which manufacturers issue for handling and ground time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, a B747-8 has (according to &lt;a href=&quot;http://www.boeing.com/assets/pdf/commercial/airports/acaps/747_8.pdf&quot;&gt;747-8 Airplane Characteristics for Airport Planning&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;maximum usable fuel capacity of about 59,734 U.S. gallons or 226,113 liters&lt;/li&gt;&#xA;&lt;li&gt;8 fueling nozzles&lt;/li&gt;&#xA;&lt;li&gt;max fueling rate of 500 US gpm  (1,890 lpm) per nozzle&lt;/li&gt;&#xA;&lt;li&gt;total max fuel pressure 50 PSIG &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Therefore, in theory it's possible to refuel an empty B747-8 to its maximum usable fuel capacity in 15 min with all 8 nozzles. In normal refueling configuration two trucks (one truck each wing) being used which serves 4 pressure nozzle and takes 30 min to refuel 56,553 US gallons. So standard fueling time for this aircraft estimated about 50 min.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For A320-200 though these ratings are (according to &lt;a href=&quot;http://www.slideshare.net/FernandoNobre1/airbus-a320-airplane-characteristics-for-airport-planning&quot;&gt;Airbus A320 airplane characteristics for airport planning&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;maximum usable fuel capacity of 6,303 U.S. gallons or 23,859 liters&lt;/li&gt;&#xA;&lt;li&gt;6 fueling nozzles&lt;/li&gt;&#xA;&lt;li&gt;max fueling rate 369.84 US gpm  (1,400 lpm) per nozzle&lt;/li&gt;&#xA;&lt;li&gt;total max fuel pressure 50 PSIG&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And the estimated fueling time is about 15 min refueling 6,303 U.S. gallons using one truck serving two nozzles. &lt;/p&gt;&#xA;" OwnerUserId="13998" LastEditorUserId="8667" LastEditDate="2016-03-14T13:32:22.883" LastActivityDate="2016-03-14T13:32:22.883" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26138" PostTypeId="1" CreationDate="2016-03-14T01:09:31.223" Score="1" ViewCount="1203" Body="&lt;p&gt;I'm taking a flight to Japan this summer and noticed that on United, they may have wifi but it says everywhere that no voice calls or video calls are permitted and strictly prohibited during flight. They don't say why, but out of curiosity why is that such a big deal?&lt;/p&gt;&#xA;" OwnerUserId="14001" LastEditorUserId="14957" LastEditDate="2016-10-22T14:51:20.400" LastActivityDate="2016-10-22T14:51:20.400" Title="Why are videos call and voice calls prohibited on airplanes?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="2" CommentCount="3" ClosedDate="2016-03-14T03:54:34.767" ContentLicense="CC BY-SA 3.0" />
  <row Id="26139" PostTypeId="2" ParentId="26138" CreationDate="2016-03-14T01:18:00.000" Score="8" Body="&lt;p&gt;Voice/video calls have not been approved by the FAA, and no one is particularly interested in having them approved, due to the frustration it would cause amongst passengers, having to listen to a multitude of conversations in a confined space, throughout the flight. Not to mention the fact that it would clog the limited bandwidth if even a sizable chunk of the passengers wanted to do it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Virgin comes right out and says it with something along the lines of &quot;For the safety and comfort of our guests, VoIP and Video Chat is also prohibited&quot;.&lt;/p&gt;&#xA;" OwnerUserId="14000" LastActivityDate="2016-03-14T01:18:00.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26140" PostTypeId="2" ParentId="26138" CreationDate="2016-03-14T01:22:27.663" Score="-2" Body="&lt;p&gt;The FCC does not approve of cell use and airplanes. One of the reasons is it wreaks havoc on cell systems because of frequent cell changes.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-03-14T01:22:27.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26141" PostTypeId="1" AcceptedAnswerId="26148" CreationDate="2016-03-14T02:32:09.247" Score="17" ViewCount="3005" Body="&lt;p&gt;Other than extra braking and reverse thrust, is there a specific short-field landing technique for large jet airliners? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In discussions about the famous landings at &lt;a href=&quot;http://travel.spotcoolstuff.com/caribbean/saint-maarten/maho-beach-airplane-spotting&quot;&gt;St Maarten&lt;/a&gt;, it is sometimes said that part of the reason for the low passes is due to the relatively short runway, so the 747s try to land right on the numbers, rather than the usual technique of touching down within the first third of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a procedure is fine in a Cessna, but in a large passenger jet? I have my doubts.&lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2019-08-10T10:55:33.507" Title="Do large airliners have a short-field landing technique?" Tags="&lt;airliner&gt;&lt;landing&gt;&lt;pilot-technique&gt;" AnswerCount="4" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26142" PostTypeId="2" ParentId="26084" CreationDate="2016-03-14T02:41:00.740" Score="4" Body="&lt;p&gt;For GA aircraft that stay at lower attitudes carrying the extra fuel for a direct flight certainly amounts to more fuel burn. But It seems to me that, in the case of large airliners, the process of landing then taking off would burn more fuel than just flying past. So I ran some numbers through a flight sim fuel calculator to see what I got.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used the calculator at &lt;a href=&quot;http://www.simbrief.com/&quot; rel=&quot;nofollow&quot;&gt;Simbrief.com&lt;/a&gt;. I have no idea of the real-world accuracy of it, but it took a lot of variables into account.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I used a their 777-200ER model for a flight from LAX to JFK with 250 passengers. BOS was alternate. I routed it over the MCI VORTAC (which a great circle route comes within a few NM of anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It calculated trip fuel at 54,878 lbs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I then ran it with a stop at MCI. I used the same SID out of LAX and the same STAR into JFK.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It calculated the LAX-MCI leg fuel at 32,280 lbs, and the MCI-JFK leg at 28,676 for a total trip of 60,956.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stopping at MCI took 6,078 lbs. more fuel,which is about 11%. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The farther off the route the stop is the bigger difference that would be. The reason non-stop flights generally cost more than connecting flights obviously has more to do with economics, passenger logistics and convenience than fuel cost.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-03-14T03:27:44.323" LastActivityDate="2016-03-14T03:27:44.323" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26143" PostTypeId="2" ParentId="26118" CreationDate="2016-03-14T03:13:27.510" Score="5" Body="&lt;p&gt;Yes. But only partial flaps will help; full flaps are almost always a poor choice for takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you describe was the standard operating procedure for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot; rel=&quot;nofollow noreferrer&quot;&gt;Messerschmitt Me-262&lt;/a&gt;s in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Jagdverband_44&quot; rel=&quot;nofollow noreferrer&quot;&gt;JV 44&lt;/a&gt;. Due to the low thrust at low speed it had a very long takeoff run, and to operate from short airfields designed for propeller aircraft and hastily repaired after attacks it needed to employ this technique. Note on the picture below the small deflection angle, however: This only worked well when the takeoff run was made with zero flaps and then takeoff flaps (not full flaps!) were added shortly before rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downside was the risk of an overshoot in case the flaps failed to deploy. If your airfield is long enough, it is certainly safer to set the flaps at the beginning of the takeoff run.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qpCjw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qpCjw.jpg&quot; alt=&quot;Me-262 two-seater replica taking off&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Me-262 two-seater replica taking off (picture &lt;a href=&quot;http://www.sandersaircraft.com/restoration/me262/SAcs_1515-1024.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-14T11:01:10.357" LastActivityDate="2016-03-14T11:01:10.357" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26144" PostTypeId="1" AcceptedAnswerId="26154" CreationDate="2016-03-14T04:03:03.570" Score="10" ViewCount="3299" Body="&lt;p&gt;I am reading about 'Tower Enroute Control' and I saw this on wikipedia &quot;Tower en-route control is a collection of published low-altitude, short-distance IFR routes through large metropolitan areas that require no level of air traffic control higher than approach-control facilities&quot; I also see that you can get these out of the A/FD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is when do you use tower en-route control? Is it commonly used or rarely used? How is an IFR flight different when on a tower en-route control flight then on say, a preferred route? &lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="11787" LastEditDate="2016-06-22T14:19:03.500" LastActivityDate="2016-06-22T14:19:03.500" Title="What exactly is tower enroute control? Is this similar to 'preferred routes'?" Tags="&lt;instrument-flight-rules&gt;&lt;navigation&gt;&lt;ifr-navigation&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26145" PostTypeId="2" ParentId="26084" CreationDate="2016-03-14T04:13:05.000" Score="5" Body="&lt;p&gt;If the total distance is long enough, flying it in several trips is more fuel efficient. In &lt;a href=&quot;https://aviation.stackexchange.com/questions/8652/how-can-i-calculate-the-fuel-consumption-of-an-airbus-320-200-at-various-loads/8654?s=1%7C0.2088#8654&quot;&gt;this answer&lt;/a&gt; I have used Breguet's equation to calculate the fuel required to fly a fully loaded A320-200 over 2000 km and 5700 km. The first trip needs 5 tons of fuel while the second needs 18.1 tons. This means the longer trip needs 27% more fuel per km of distance because more fuel is transported and the aircraft is heavier over most of the trip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, flight through lower, denser air is less efficient in terms of distance flown per unit of fuel burnt, so you need to find an optimum between flying mostly near the ground and flying with a heavier aircraft. On the other hand, the lighter aircraft will climb much faster, so the time spent at low altitude is lower per climb segment in case of the staged legs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, if the total distance is big enough to allow for several hops while still only a fraction of the total flight time is spent at lower altitude, the overall fuel consumption is easily lower.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-03-14T04:13:05.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26146" PostTypeId="2" ParentId="26105" CreationDate="2016-03-14T06:04:50.133" Score="3" Body="&lt;p&gt;It looks to me in your top image that the air vent is right there at the center of the ceiling. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/CjNXP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It looks like a linear slot diffuser running the length of the cabin.  Similar to this&#xA;&lt;img src=&quot;https://i.stack.imgur.com/iIGIy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-14T06:04:50.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26147" PostTypeId="1" CreationDate="2016-03-14T07:01:13.123" Score="6" ViewCount="1399" Body="&lt;p&gt;Clearly some flight testing and certification process is used to establish whether or not a type of production GA aircraft is or is not placarded &quot;SPINS PROHIBITED&quot;. What type of testing and what results determine the outcome/certification? What does such a result mean for the aircraft's actual performance in a spin/recovery situation? I know spin certification is completed with a recovery parachute mounted to the tail in case of an unrecoverable spin and that an aircraft must recover within 6 turns to be certified (unless you are Cirrus and have a parachute) but what else is there?&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="19" LastEditDate="2017-01-01T21:16:25.770" LastActivityDate="2017-01-01T21:16:25.770" Title="What are the regulations and testing that determine whether a &quot;Spins Prohibited&quot; placard is required in an aircraft?" Tags="&lt;faa-regulations&gt;&lt;aircraft-certification&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26148" PostTypeId="2" ParentId="26141" CreationDate="2016-03-14T11:11:58.183" Score="17" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Other than extra braking and reverse thrust, is there a specific short-field landing technique for large jet airliners?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Never heard of any. The required landing distance is calculated so that the plane can reliably stop (even if reversers fail) and landing at shorter runway is not allowed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;so the 747s try to land right on the numbers, rather than the usual technique of touching down within the first third of the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The usual technique is to aim for 1,000 ft down the runway and touch down with some flare somewhere around 1,500.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In discussions about the famous landings at St Maarten, it is sometimes said that part of the reason for the low passes is due to the relatively short runway, so the 747s try to land right on the numbers&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Actually the &lt;a href=&quot;http://ourairports.com/airports/TNCM/&quot;&gt;TNCM&lt;/a&gt; runway 10 has PAPI and TDZ marking a little beyond the usual 1,000 ft mark at around 1,250 ft. &lt;a href=&quot;http://ourairports.com/airports/TNCM/pilot-info.html&quot;&gt;Ourairports says&lt;/a&gt; the threshold is displaced 162 ft (but it also says runway 9, so it is likely out of date), but according to the satellite images it is a bit over 300 ft plus some runway end safety area, placing the threshold around 500 ft past the fence and the touch-down zone around 1,750 ft past the fence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now the normal glide-slope is around 5%. That means the aircraft is supposed to cross the fence at around 90 ft, on &lt;em&gt;average&lt;/em&gt;. That seems about right. Of course you can't expect every aircraft to be positioned precisely within a few feet, so now and then some crosses it at maybe 50 ft. That is not intention, but simply a deviation. But of course the photos of planes flying especially low are more likely to be picked for publishing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, a short field landing normally calls for &lt;em&gt;steep&lt;/em&gt; approach which make precise aim for landing spot easier. That would actually place the aircraft &lt;em&gt;higher&lt;/em&gt; over the beach. But the glide-slope at TNCM is normal 3° (5%) one, so it is not a steep approach.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Such a procedure is fine in a Cessna, but in a large passenger jet? I have my doubts.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In large jet it isn't. Air transport has stricter regulations than general aviation because more is at stake and larger aircraft have stricter limits because the higher energies involved mean errors are harder to fix and have more serious consequences.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-14T13:58:20.613" LastActivityDate="2016-03-14T13:58:20.613" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26150" PostTypeId="1" AcceptedAnswerId="26153" CreationDate="2016-03-14T12:34:54.760" Score="7" ViewCount="1771" Body="&lt;p&gt;Why is it numbers are not always pronounced in a phonetic way? For example a flight number of 2390 is pronounced &quot;twenty-three ninety&quot; instead of &quot;two three niner zero&quot;&lt;/p&gt;&#xA;" OwnerUserId="14005" LastEditorUserId="12220" LastEditDate="2016-03-14T15:29:52.543" LastActivityDate="2016-03-14T15:29:52.543" Title="Why are aircraft callsigns pronounced over the radio in a non-phonetic alphabet way?" Tags="&lt;faa-regulations&gt;&lt;radio-communications&gt;&lt;phraseology&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26151" PostTypeId="1" CreationDate="2016-03-14T13:46:42.667" Score="1" ViewCount="43" Body="&lt;p&gt;On the east coast, we have a lot of Air Force/Naval bases that are listed on sectionals.  Is there a quick way to determine that an airport is one of these?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t2FIH.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t2FIH.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13972" LastActivityDate="2016-03-14T13:46:42.667" Title="On a sectional, is there a way to determine if an airport is an Air Force/Naval base?" Tags="&lt;airport&gt;&lt;map&gt;" AnswerCount="0" CommentCount="6" ClosedDate="2016-03-14T13:58:01.403" ContentLicense="CC BY-SA 3.0" />
  <row Id="26153" PostTypeId="2" ParentId="26150" CreationDate="2016-03-14T13:58:59.900" Score="12" Body="&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;FAA's ATC orders&lt;/a&gt; (section 2-4-20) say that the 'group form' should be used by controllers when talking to any aircraft with an FAA authorized call sign. So you would expect to hear it with airline traffic but not private flights:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;Air carrier and other civil aircraft having FAA authorized call signs. State the call sign followed by the flight number in group&#xA;  form.  &lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;NOTE-&lt;/strong&gt; &lt;em&gt;“Group form” is the pronunciation of a series of numbers&#xA;  as the whole number, or pairs of numbers they represent rather than&#xA;  pronouncing each separate digit. The use of group form may, however,&#xA;  be negated by four-digit identifiers or the placement of zeros in the&#xA;  identifier.&lt;/em&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;EXAMPLE−&lt;/strong&gt; &lt;em&gt;“American Fifty−Two.” “Delta One Hundred.” “Eastern&#xA;  Metro One Ten.” “General Motors Thirty Fifteen.” “United One Zero&#xA;  One.” “Delta Zero One Zero.” “TWA Ten Zero Four.”&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-14T13:58:59.900" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26154" PostTypeId="2" ParentId="26144" CreationDate="2016-03-14T14:24:59.110" Score="4" Body="&lt;p&gt;Tower enroute control is similar to the preferred route in that both are designed to improve the system effeciency. FAA defines the Tower En  Route Control (TEC) (in AIM section 4-1-19) as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TEC is an ATC program to provide a service to aircraft proceeding to and from metropolitan areas. It links designated Approach Control Areas by a network of identified routes made up of the existing airway structure of the National Airspace System.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Preferred routes, on the other hand (from &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/Chapter_2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Procedures Handbook&lt;/a&gt;) are defined as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Preferred IFR routes are established between busier airports to increase system efficiency and capacity. They normally extend through one or more ARTCC areas and are designed to  achieve  balanced  traffic  flows  among  high  density terminals.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This outlines one of the major differences between the two: in TEC route, you never 'talk' to the ARTCC. As &lt;a href=&quot;http://www.flyingmag.com/technique/tip-week/tower-en-route-control&quot; rel=&quot;nofollow noreferrer&quot;&gt;flyingmag notes&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TEC flights are intended to be relatively short — generally two hours or less, and are conducted below 10,000 feet. Throughout the route, communications are managed through tower controllers, and departure and approach controllers at a TRACON facility. You will never talk to ARTCC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another important thing is that the TEC is essentially equivalent of getting a pop-up IFR clearance, &lt;a href=&quot;https://aviation.stackexchange.com/questions/13403/can-atc-decide-whether-or-not-to-provide-tower-enroute-services?lq=1&quot;&gt;as already noted&lt;/a&gt; (from AIM section 4-1-19):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There are no unique requirements upon pilots to use the TEC program. Normal flight plan filing procedures will ensure proper flight plan processing. Pilots should include the acronym “TEC” in the remarks section of the flight plan when requesting tower en route control.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The TEC is established only in areas with Radar coverage. US DoT &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/AT%207110.5A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;WP AT 7110.5A&lt;/a&gt; specifically notes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;TEC should be established/expanded only within areas of radar coverage. In areas without radar coverage ... an equivalent level of safety is maintained, TEC may be established and/or expanded. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;TECs basically are published preferred IFR routes that are entirely in TRACON airspace. As a result, most of the TECs are in the northeast and the west coast (which can be found &lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;), where the airspaces are close enough that one can fly with Radar coverage the whole way.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-03-14T14:24:59.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26155" PostTypeId="2" ParentId="26147" CreationDate="2016-03-14T14:26:47.467" Score="5" Body="&lt;p&gt;Spins require a demonstration for certification, but can be bypassed with an FAA waiver as Cirrus did for the SR-20/22. The waiver was granted under the understanding that the &lt;strong&gt;only&lt;/strong&gt; way to recover a Cirrus is to pull the chute.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=685dc1ae97ae3f5e5569e47880fab01e&amp;amp;mc=true&amp;amp;node=pt14.1.23&quot; rel=&quot;noreferrer&quot;&gt;FAA CFR Part 23&lt;/a&gt; governs the process and requirements for certifying general aviation aircraft. Specifically for spins you are wanting to read &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=685dc1ae97ae3f5e5569e47880fab01e&amp;amp;mc=true&amp;amp;node=pt14.1.23#se14.1.23_1221&quot; rel=&quot;noreferrer&quot;&gt;CFR 23.221&lt;/a&gt; which outlines the process of spin testing:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(a) Normal category airplanes. A single-engine, normal category airplane must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery, or demonstrate compliance with the optional spin resistant requirements of this section.&lt;/p&gt;&#xA;&lt;p&gt;(1) The following apply to one turn or three second spins:&lt;/p&gt;&#xA;&lt;p&gt;(i) For both the flaps-retracted and flaps-extended conditions, the applicable airspeed limit and positive limit maneuvering load factor must not be exceeded;&lt;/p&gt;&#xA;&lt;p&gt;(ii) No control forces or characteristic encountered during the spin or recovery may adversely affect prompt recovery;&lt;/p&gt;&#xA;&lt;p&gt;(iii) It must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin; and&lt;/p&gt;&#xA;&lt;p&gt;(iv) For the flaps-extended condition, the flaps may be retracted during the recovery but not before rotation has ceased.&lt;/p&gt;&#xA;&lt;p&gt;(2) At the applicant's option, the airplane may be demonstrated to be spin resistant by the following:&lt;/p&gt;&#xA;&lt;p&gt;(i) During the stall maneuver contained in §23.201, the pitch control must be pulled back and held against the stop. Then, using ailerons and rudders in the proper direction, it must be possible to maintain wings-level flight within 15 degrees of bank and to roll the airplane from a 30 degree bank in one direction to a 30 degree bank in the other direction;&lt;/p&gt;&#xA;&lt;p&gt;(ii) Reduce the airplane speed using pitch control at a rate of approximately one knot per second until the pitch control reaches the stop; then, with the pitch control pulled back and held against the stop, apply full rudder control in a manner to promote spin entry for a period of seven seconds or through a 360 degree heading change, whichever occurs first. If the 360 degree heading change is reached first, it must have taken no fewer than four seconds. This maneuver must be performed first with the ailerons in the neutral position, and then with the ailerons deflected opposite the direction of turn in the most adverse manner. Power and airplane configuration must be set in accordance with §23.201(e) without change during the maneuver. At the end of seven seconds or a 360 degree heading change, the airplane must respond immediately and normally to primary flight controls applied to regain coordinated, unstalled flight without reversal of control effect and without exceeding the temporary control forces specified by §23.143(c); and&lt;/p&gt;&#xA;&lt;p&gt;(iii) Compliance with §§23.201 and 23.203 must be demonstrated with the airplane in uncoordinated flight, corresponding to one ball width displacement on a slip-skid indicator, unless one ball width displacement cannot be obtained with full rudder, in which case the demonstration must be with full rudder applied.&lt;/p&gt;&#xA;&lt;p&gt;(b) Utility category airplanes. A utility category airplane must meet the requirements of paragraph (a) of this section. In addition, the requirements of paragraph (c) of this section and §23.807(b)(7) must be met if approval for spinning is requested.&lt;/p&gt;&#xA;&lt;p&gt;(c) Acrobatic category airplanes. An acrobatic category airplane must meet the spin requirements of paragraph (a) of this section and §23.807(b)(6). In addition, the following requirements must be met in each configuration for which approval for spinning is requested:&lt;/p&gt;&#xA;&lt;p&gt;(1) The airplane must recover from any point in a spin up to and including six turns, or any greater number of turns for which certification is requested, in not more than one and one-half additional turns after initiation of the first control action for recovery. However, beyond three turns, the spin may be discontinued if spiral characteristics appear.&lt;/p&gt;&#xA;&lt;p&gt;(2) The applicable airspeed limits and limit maneuvering load factors must not be exceeded. For flaps-extended configurations for which approval is requested, the flaps must not be retracted during the recovery.&lt;/p&gt;&#xA;&lt;p&gt;(3) It must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin.&lt;/p&gt;&#xA;&lt;p&gt;(4) There must be no characteristics during the spin (such as excessive rates of rotation or extreme oscillatory motion) that might prevent a successful recovery due to disorientation or incapacitation of the pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Another good read is the &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/order/8110.41a.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Certification Service - FAA Flight Test Responsibilities, Procedures, and Training&lt;/a&gt; which states:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;506. Spin Tests.&lt;/strong&gt; Spin tests conducted by FAA FTPs should be flown initially with a spin chute (or equivalent equipment) installed on the aircraft and approved by an FAA structural and/or systems engineer. (See Appendix 3 for additional guidance on requirements for spin recovery devices). &lt;strong&gt;After all spin modes have been evaluated and found satisfactory, the spin characteristics should be checked with the external spin chute removed&lt;/strong&gt;, unless it is determined&#xA;that the spin chute installation has no significant effect on spin characteristics.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(Emphasis Mine)&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-14T14:32:14.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26157" PostTypeId="2" ParentId="22849" CreationDate="2016-03-14T15:28:18.270" Score="0" Body="&lt;p&gt;Turboprops area complex, certainly because of the gear and flaps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the prop, of course, some do have prop levers, but many single-engine FADEC systems have electric prop governors. In the case of 2-lever systems, like the TBM and the PC-12, there is a &lt;em&gt;condition lever&lt;/em&gt; which does indeed control the prop, even though only in certain regimes of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/20978/what-does-the-condition-lever-in-turboprops-control&quot;&gt;What does the condition lever in turboprops control?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-03-14T15:28:18.270" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26158" PostTypeId="2" ParentId="26141" CreationDate="2016-03-14T16:43:50.773" Score="6" Body="&lt;p&gt;I'm not aware of any short field landing techniques for large commercial airliners. But some of the &lt;a href=&quot;http://boeing.mediaroom.com/2006-07-31-Boeing-Delivers-First-737-with-Enhanced-Short-Runway-Package-to-GOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;do offer some modifications&lt;/a&gt;, that offer improved short field performance. Most of these modifications are aimed at operating the airliners at the Santos Dumont airport, which has a short runway. According to Boeing,&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The short-field design package is an option on the 737-600, -700 and -800 and is standard equipment for the new 737-900ER. The enhancements increase payload capability for landing up to 8,000 pounds on the 737-800 and 737-900ER and up to 4,000 pounds on the 737-600 and 737-700.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This is mainly done using a few modifications, which can be factory ordered or retrofitted and &lt;a href=&quot;http://www.b737.org.uk/flightcontrols.htm#Short-field_Performance_Enhancement_Program&quot; rel=&quot;nofollow noreferrer&quot;&gt;include the following changes&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Flight spoilers are capable of 60 degree deflection on touchdown by addition of increased stroke actuators.&lt;/p&gt;&#xA;&lt;p&gt;Slats are sealed for take-off to flap position 15 (compared to the current 10) to allow the wing to generate more lift at lower rotation angles.&lt;/p&gt;&#xA;&lt;p&gt;Autoslat function available from flap 1 to 25.&lt;/p&gt;&#xA;&lt;p&gt;Flap load relief function active from flap 10 or greater.&lt;/p&gt;&#xA;&lt;p&gt;Two-position tailskid that extends an extra 127mm (5ins) for landing protection. This allows greater angles of attack to be safely flown thereby reducing Vref and hence landing distance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;among others. Around 250 of these modified aircraft are in operations till date. Not to be outdone, &lt;a href=&quot;https://www.flightglobal.com/news/articles/airbus-developing-short-field-enhancement-for-a320ne-416903/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus offers similar options in its A320neo&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-08-08T00:12:59.873" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26160" PostTypeId="7" CreationDate="2016-03-14T19:15:24.297" Score="0" Body="&lt;p&gt;&#xA;    On Stack Exchange, we believe the core moderators should come &lt;i&gt;from&lt;/i&gt; the community, and be elected by the community itself through popular vote. We hold regular elections to determine who these community moderators will be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&#xA;    Community moderators are &lt;a href=&quot;http://blog.stackoverflow.com/2009/05/a-theory-of-moderation/&quot;&gt;accorded the highest level of privilege on our community&lt;/a&gt;, and should themselves be exemplars of positive behavior and leaders within the community.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&#xA;    Our general criteria for moderators is as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;    &lt;li&gt;patient and fair&lt;/li&gt;&#xA;    &lt;li&gt;leads by example&lt;/li&gt;&#xA;    &lt;li&gt;shows respect for their fellow community members in their actions and words&lt;/li&gt;&#xA;    &lt;li&gt;open to some light but firm moderation to keep the community on track and resolve (hopefully) uncommon disputes and exceptions&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&#xA;    Every election has three phases:&#xA;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;    &lt;li&gt;Nomination&lt;/li&gt;&#xA;    &lt;li&gt;Primary&lt;/li&gt;&#xA;    &lt;li&gt;Election&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&#xA;    Please participate in the moderator elections by voting, and perhaps even by nominating yourself to be a community moderator!&#xA;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://chat.stackexchange.com/rooms/97602/2019-aviation-moderator-election-chat&quot;&gt;Election chat room&lt;/a&gt; - discuss the election, candidates, etc.&lt;/li&gt;&#xA;&lt;li&gt;For questions about the election process itself, visit &lt;a href=&quot;https://aviation.meta.stackexchange.com/tags/election&quot;&gt;Meta&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;&lt;a href=&quot;https://aviation.meta.stackexchange.com/q/3881/7938&quot;&gt;The candidates answer your questions&lt;/a&gt;&lt;/strong&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="7938" LastEditDate="2019-08-19T19:57:55.323" LastActivityDate="2019-08-19T19:57:55.323" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26161" PostTypeId="1" CreationDate="2016-03-14T20:38:35.000" Score="6" ViewCount="1910" Body="&lt;p&gt;If outside the aircraft is pretty cold and inside the cabin the air temperature is different, why don't the windows become fogged up on the inside?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="62" LastEditDate="2016-03-15T14:51:13.920" LastActivityDate="2017-11-12T01:43:03.433" Title="Why doesn't condensation form on the inside of airliner windows?" Tags="&lt;airliner&gt;&lt;windows&gt;" AnswerCount="3" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26162" PostTypeId="6" CreationDate="2016-03-14T21:58:58.890" Score="0" Body="&lt;p&gt;I have been using Stack Exchange for 6 years, mostly SO, and I have been an internet user since 1989.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Over the past year or so I have become one of the &quot;regulars&quot; on &lt;em&gt;Aviation&lt;/em&gt;, and am #23 on the reputation list overall with almost 10K rep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As one of the few helicopter and glider pilots on &lt;em&gt;Aviation&lt;/em&gt;, I strive to make sure we have great questions and answers in those two topics, and I also have a special interest in Part 91 regulations and in instrument flying.  I also regularly participate in the review queue, and in editing.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-14T21:58:58.890" LastActivityDate="2016-03-14T21:58:58.890" CommentCount="2" CommunityOwnedDate="2016-03-14T21:58:58.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="26163" PostTypeId="1" CreationDate="2016-03-14T22:23:10.390" Score="0" ViewCount="136" Body="&lt;p&gt;I would like to know where ideally it is to be sat on an Emirates A380 to get a nice picture of the wing and wingtip as well as the outer landscape?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LHR-DXB 7:50 P.M&lt;/p&gt;&#xA;" OwnerUserId="14013" LastEditorUserId="7843" LastEditDate="2016-03-15T01:02:00.197" LastActivityDate="2016-03-15T01:20:32.527" Title="I would like to know where ideally it is to be sat on an Emirates A380 to get a nice picture of the wing and wingtip as well as the outer landscape?" Tags="&lt;airbus-a380&gt;&lt;seats&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-03-15T01:01:35.687" ContentLicense="CC BY-SA 3.0" />
  <row Id="26164" PostTypeId="2" ParentId="26163" CreationDate="2016-03-14T22:40:28.843" Score="1" Body="&lt;p&gt;The best seats would probably be in the back because you can see the wing and the ground without having to twist or having the wing in your view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a picture I took from the back end of a Boeing 757-200. Is it the view that you want?&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KIaBB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KIaBB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="13197" LastEditDate="2016-03-15T01:20:32.527" LastActivityDate="2016-03-15T01:20:32.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26165" PostTypeId="6" CreationDate="2016-03-14T23:11:59.580" Score="0" Body="&lt;p&gt;I'd mostly like to be a moderator because I love aviation and honestly enjoy fostering a good environment for Q&amp;amp;A for both enthusiast and professionals so others can learn about this topic (myself included!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I was made a mod, my goal would be fostering good will between users by mediating disagreements in both comments and (preferably) in chat.  Mostly by hearing out both sides of the argument and making a decision compliant with the rules in our charter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would also do my best to help the community to continue to define it's purpose and police that purpose by removing/reassigning off topic questions and by helping newer users clarify their questions to be more on topic (possibly through 1 on 1 chat sessions.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yeah, it's kind of super vague ;).  But the reality is that being a good mod just means paying close attention and listening to users who have gripes.  I feel like my history of comments on the main site, meta and chat prove that I have the patience and ability to do this.  And I think a review of my user profile shows that I have a vested interest in this community, and aviation in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, if you don't pick me, pick Vorteq7, because that guy is an awesome mod..&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-03-14T23:42:39.403" LastActivityDate="2016-03-14T23:42:39.403" CommentCount="5" CommunityOwnedDate="2016-03-14T23:11:59.580" ContentLicense="CC BY-SA 3.0" />
  <row Id="26167" PostTypeId="2" ParentId="26161" CreationDate="2016-03-14T23:22:40.093" Score="8" Body="&lt;p&gt;The humidity at the altitude airliners fly at is VERY low. However, a tiny bit of moisture does build up - if you look closely you'll see little ice crystals on the window (it's also very cold up there - in the negative degrees F usually). On top of that - airliners have multiple air conditioning &quot;packs&quot; that dehumidify the cabin air so there would be indeed by very little moisture to condense on the inside of the windows. Also, if you look at the windows - they are often two or three layers with quite a bit of space separating the outside of the window from the inside (often multiple inches). Some of this is for pressurization and some of this is for thermal insulation. The VERY cold outdoor air is not in direct contact with the inside cabin pane.&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2016-03-15T06:50:33.327" LastActivityDate="2016-03-15T06:50:33.327" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26168" PostTypeId="1" CreationDate="2016-03-14T23:34:42.820" Score="10" ViewCount="1868" Body="&lt;p&gt;I need to clean my aircraft's windows what do I use?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I hope this is not a &quot;subjective&quot; question, as I don't want to put a potential harmful substance on my aircraft's windows and as a new aircraft owner, I would think this would be a logical question.&lt;/p&gt;&#xA;" OwnerUserId="13972" LastActivityDate="2016-03-15T03:38:18.560" Title="I need to clean my aircraft's windows - what do I use?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26169" PostTypeId="1" AcceptedAnswerId="26209" CreationDate="2016-03-14T23:40:27.250" Score="13" ViewCount="6505" Body="&lt;p&gt;What should I wash my airplane off with?  As a new aircraft owner, any help would be appreciated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am pretty sure using dish washing detergent is not the best here as we are told not to use the stuff on our cars.&lt;/p&gt;&#xA;" OwnerUserId="13972" LastActivityDate="2016-03-20T16:04:42.220" Title="What should I wash my plane with?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26170" PostTypeId="2" ParentId="26168" CreationDate="2016-03-14T23:49:35.300" Score="3" Body="&lt;p&gt;Great article &lt;a href=&quot;http://www.lpaero.com/careins.html&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; on the subject.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most important bit of information is to rinse the windows thoroughly with water before touching them. Will rinse away any of the larger bits and pieces that will cause scratching of the window.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also very important, is NOT using glass cleaner. Assuming here that you have acrylic windows, and the ammonia contained in most glass cleaners will cause crazing (very tiny cracks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best option for cleaning acrylic windows is actually your bare hand, and cleaning with a cotton rag (old t-shirt). The article linked above contains more of what not to get on your windows than it does of what to use, which is far more important in my opinion. A few bugs left on the windows is far better than a ruined window that requires replacing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope that helps.&lt;/p&gt;&#xA;" OwnerUserId="14000" LastEditorUserId="14000" LastEditDate="2016-03-15T00:17:55.187" LastActivityDate="2016-03-15T00:17:55.187" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26171" PostTypeId="2" ParentId="26169" CreationDate="2016-03-14T23:52:59.110" Score="0" Body="&lt;p&gt;Wash it just as you would your car. Soap and water. Of course, be sure not to clog up static ports with anything.&lt;/p&gt;&#xA;" OwnerUserId="14000" LastActivityDate="2016-03-14T23:52:59.110" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26173" PostTypeId="1" AcceptedAnswerId="26174" CreationDate="2016-03-15T00:31:07.860" Score="30" ViewCount="21347" Body="&lt;p&gt;I was going through social media and I came across this GIF image that showed a plane doing some sort of roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iaVDu.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iaVDu.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was labeled &quot;Barrel Roll&quot; but in the comments to the post, someone said that it was an &quot;Aileron Roll&quot;. What is the difference between a barrel roll and an aileron roll?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2016-03-15T14:51:37.993" LastActivityDate="2019-07-14T18:33:28.213" Title="What is the difference between a barrel roll and an aileron roll?" Tags="&lt;aerobatics&gt;&lt;maneuver&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26174" PostTypeId="2" ParentId="26173" CreationDate="2016-03-15T00:55:11.200" Score="34" Body="&lt;p&gt;The difference between an aileron roll and a barrel roll is that an aileron roll's centre of rotation is very close to or on the aircraft. A barrel roll has its centre of rotation around a point further away from the aircraft itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference can be appreciated in this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZcHgS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZcHgS.png&quot; alt=&quot;Image showing path of plane for barrel and aileron rolls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://mpora.com/skydiving-wingsuits/we-had-a-go-in-a-300000-red-bull-air-race-plane-and-threw-up-a-lot&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image Source&lt;/a&gt; You can find out about the difference in feeling that these two manoeuvres have.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having stated these things, the manoeuvre shown in the GIF is certainly an aileron roll.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-02T15:55:07.300" LastActivityDate="2016-04-02T15:55:07.300" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26175" PostTypeId="2" ParentId="26173" CreationDate="2016-03-15T01:42:29.470" Score="22" Body="&lt;p&gt;In a barrel roll, the aircraft rotates both in its longitudinal and lateral axes, while in case of aileron roll, the rotation is only about the longitudinal axis. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MGlqD.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MGlqD.jpg&quot; alt=&quot;Barrel roll&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A barrel roll, image from &lt;a href=&quot;http://www.flightsimbooks.com/f15strikeeagle/04_05_The_Barrel_Roll.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;flightsimbooks.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If properly executed, there is no change in alttitude in case of an aileron roll, while during barrel roll, the aircraft follows a helical path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/l7eX5.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l7eX5.gif&quot; alt=&quot;aileron roll&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aileron roll, image from &lt;a href=&quot;http://www.globalsecurity.org/military/systems/aircraft/intro-performance.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;globalsecurity.org&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, think like this- in a barrel roll, the aircraft goes along the surface of the barrel, while in an aileron roll, the aircraft corkscrews around inside a barrel, with the wingtips grazing the barrel surface.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-15T01:42:29.470" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26176" PostTypeId="2" ParentId="26168" CreationDate="2016-03-15T03:29:37.657" Score="5" Body="&lt;p&gt;I assume that your aircraft has &lt;a href=&quot;https://en.wikipedia.org/wiki/Poly(methyl_methacrylate)&quot;&gt;acrylic&lt;/a&gt; windows. This is a very soft material which is easily scratched and cracks under stress. For cleaning, use these steps:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rinse with lots of water to remove dust.&lt;/li&gt;&#xA;&lt;li&gt;Wipe with a wet, soft sponge. Don't press on the sponge and move it in the direction of airflow. Moving the sponge sideways will increase the risk of sideways scratches which are caused by the movement of dirt particles over the acrylic surface. Those sideways scratches will impair vision when flying into the direction of a low sun.&lt;/li&gt;&#xA;&lt;li&gt;Dry the surface with a chamois leather, again moving in flow direction.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Superficial scratches can be removed by &lt;a href=&quot;https://www.youtube.com/watch?v=PNoOPXi_4o4&quot;&gt;polishing the surface with an acrylic or metal polish&lt;/a&gt;. Be careful with sandpaper because this could take off more material than necessary, resulting in optical distortions when looking through the polished area at an angle. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never use alcohol or other organic solvents!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-15T03:38:18.560" LastActivityDate="2016-03-15T03:38:18.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26177" PostTypeId="1" AcceptedAnswerId="26182" CreationDate="2016-03-15T04:43:48.660" Score="7" ViewCount="5328" Body="&lt;p&gt;In my Cessna 152 POH it is written that the horsepower rating is 110BHP at 2550RPM. My question is: is it 100% of the power of my engine or, as someone told me, if I open full throttle I will get 75% BHP? If so, then why don't I get 100% BHP at 2550 RPM? And is there any relationship between the mixture setting and BHP?&lt;/p&gt;&#xA;" OwnerUserId="13956" LastEditorUserId="62" LastEditDate="2016-05-15T20:56:52.877" LastActivityDate="2016-05-15T20:56:52.877" Title="What is my BHP if I open full throttle and how is it controlled?" Tags="&lt;aircraft-performance&gt;&lt;piston-engine&gt;&lt;cessna-152&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26178" PostTypeId="1" AcceptedAnswerId="26180" CreationDate="2016-03-15T08:10:47.113" Score="17" ViewCount="1913" Body="&lt;p&gt;This is a boomer operator:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d6rZb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d6rZb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_refueling#/media/File:KC-135Boom-operator-521.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt; by John E. Lasky - United States Air Force)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If he is not refueling an aircraft, or the plane is not on a refueling mission, what is he doing? Is he sitting in that small cabin all the time, or is he free to move on the aircraft? Can his role be taken by anybody from the crew, or is he the only person on board who can handle the refueling boom?&lt;/p&gt;&#xA;" OwnerUserId="13431" LastEditorUserId="13431" LastEditDate="2016-03-15T08:17:58.710" LastActivityDate="2016-03-15T14:43:54.857" Title="What is the work routine of a boomer operator in a refueling aircraft?" Tags="&lt;crew&gt;&lt;refueling&gt;&lt;mid-air-refueling&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26179" PostTypeId="6" CreationDate="2016-03-15T13:26:22.060" Score="0" Body="&lt;p&gt;Hello friends,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since always, I have loved airplanes. That is why I have been following Aviation.SE even when it was a concept on Area 51. And then joined it on the very first day, before public beta.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why I want to be a mod? Of course I love aviation. We all do. In addition to this affection and fondness, there are certain attributes I want to highlight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I'm always learning. I don't feel embarrassed when I don't know something and always try to get knowledge for &lt;em&gt;any&lt;/em&gt; source possible.&lt;/li&gt;&#xA;&lt;li&gt;I've been very active in mod duties based on my rep level. Reviewing, flagging, improving, you name it and I'm doing it.&lt;/li&gt;&#xA;&lt;li&gt;I'm the very first recipient of Copy Editor gold badge. (done over 700 edits so far).&lt;/li&gt;&#xA;&lt;li&gt;I always appreciate others and was the first recipient of Electorate gold badge. (standing 3rd on voters table). I don't downvote as criticizing doesn't always help.&lt;/li&gt;&#xA;&lt;li&gt;I actively participated to revive the blog site.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Why I should not be a mod. Because I do not know everything. That doesn't look good but this reason alone helped me continuously increase my knowledge, learn more, and help others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for your time.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;This is a lot of self praise. Glad there's a 1200 char limit.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="65" LastEditorUserId="65" LastEditDate="2016-03-15T17:47:09.753" LastActivityDate="2016-03-15T17:47:09.753" CommentCount="8" CommunityOwnedDate="2016-03-15T13:26:22.060" ContentLicense="CC BY-SA 3.0" />
  <row Id="26180" PostTypeId="2" ParentId="26178" CreationDate="2016-03-15T13:39:30.197" Score="14" Body="&lt;p&gt;The boom operator (or boomer) can freely move around the aircraft. The boom operator position is usually accessible from the cargo hold and the operator can use the opening to move from his/her position. This is especially important for the KC-135 Stratotanker, which has the boom operator working in a prone position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4CgMG.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4CgMG.gif&quot; alt=&quot;KC-135&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://sobchak.files.wordpress.com/2009/09/kc135cutaway.gif&quot; rel=&quot;noreferrer&quot;&gt;sobchak.files.wordpress.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the operator is not fueling other aircraft, he/she has other responsibilities to carry out. According to the US military &lt;a href=&quot;http://usmilitary.about.com/od/airforceenlistedjobs/a/afjob1a0x1.htm&quot; rel=&quot;noreferrer&quot;&gt;job description of a boom operator&lt;/a&gt;, the boomer,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Prepares and verifies load plans, directs cargo loading, and unloading operations, and inspects aircraft load to ensure hazardous cargo compliance and weight and balance status of aircraft. Ensures adequate safety equipment and passenger comfort items are on aboard aircraft. Instructs passengers in use of emergency equipment and emergency procedures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;among other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The boom operator is a specialist and his/her job cannot be done by anyone else on board. The operator also has to be qualified for the type of aircraft he/she is refueling. From &lt;a href=&quot;http://foxtrotalpha.jalopnik.com/confessions-of-a-usaf-kc-135-flying-gas-station-boom-op-1578048155&quot; rel=&quot;noreferrer&quot;&gt;interview of a USAF boom operator in foxtrotalpha&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Every receiver is a little different, so we have specific qualifications for heavy aircraft and fighter aircraft, called gulf and Charlie. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1696" LastEditDate="2016-03-15T14:43:54.857" LastActivityDate="2016-03-15T14:43:54.857" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26181" PostTypeId="6" CreationDate="2016-03-15T15:18:57.457" Score="0" Body="&lt;p&gt;Hello everyone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am nominating myself and is then reasonable for you to demand an explanation of why I think I would be fit to serve as a moderator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me start off by saying that this would not be my first moderator appointment, sure, it would be the first in a StackExchange site, but I believe that some experiences I had in the past will help me to deal with what might be expecting me here.&lt;br&gt;&#xA;I am convinced that part of this experience shows in my stats: out of 243 generic flags raised, 228 (something shy of 94%) have been deemed useful; out of 50 spam flags, 49 have been useful, while only one has aged away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since I began participating 2 years ago, I have tried to be as active as possible, both as a member and as a reviewer: I am one of the few to have the &quot;Fanatic&quot; badge on meta and I am quite active in the review queues (I am one of the 2 people that has 4 &quot;Reviewer&quot; badges).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am also a strong supporter of mutual understanding and I would continue down this path during my appointment; I realise that sometimes this might come across as confrontational, but I think a community thrives on open discussion aimed at finding common ground, be it with meta posts or chat.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-03-15T15:18:57.457" LastActivityDate="2016-03-15T15:18:57.457" CommentCount="2" CommunityOwnedDate="2016-03-15T15:18:57.457" ContentLicense="CC BY-SA 3.0" />
  <row Id="26182" PostTypeId="2" ParentId="26177" CreationDate="2016-03-15T16:00:12.710" Score="8" Body="&lt;p&gt;Rated BHP is measured at sea-level on a standard day. For the Cessna 152 I'm guessing you have an O235-L2 which is rated at 110HP @ 2550 RPM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now to understand how mixture affects the power produced by the engine you need to understand that the mixture knob controls how much fuel enters the cylinders to be burned with the air. As a combustion engine sparks, the fuel ignites but there is the fire triangle, Air, Fuel, Heat. Too much or too little of any of those pieces means a reduction of power or no power at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, depending on the fuel type there is an optimum &lt;a href=&quot;https://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio&quot; rel=&quot;noreferrer&quot;&gt;stoichiometric ratio&lt;/a&gt; where the proper amount of air and fuel are burned such that there is no extra air or fuel left over. For gasoline engines this is about 15:1, so for every 15 units of air, 1 unit of fuel is required. Having a richer fuel mixture results in an incomplete burn and may cool the cylinder temperatures, reducing power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the flip side, having too little fuel for the air can cause hotter cylinder temperatures and hot-spots on the cylinders. This causes detonation or knocking and can damage an engine very quickly. This is especially apparent in engines that have a lot of cylinder carbon deposits where the carbon can heat up and detonate the mixture before the spark plug does. Its like hitting the piston with a sledge hammer as its still coming up. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't have a graph from an O-235L but I did find one from an O-235C, which shows the relationship between throttle and BHP:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2rhoz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2rhoz.png&quot; alt=&quot;O235C Power Curve&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you can see that reducing power from 2500 RPM to 2400 RPM gives a 10% decrease in BHP produced by the engine. Running at 2350 RPM is a 75% power setting (and in this graph nicely matches up with ~75 BHP). You can also see that there is a sweet-spot with relation to fuel consumption and produced power right around the 75% mark, which is usually refered to as the &quot;performance cruise&quot; value (best speed for fuel), and at 65% for &quot;economy cruise&quot; (best fuel).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the mixture control needs to be leaned out based on the amount of air entering the engine. The levels of oxygen decrease with altitude and therefore the mixture needs to be leaned out. Its not uncommon for operations out of high altitude fields to perform take-offs with the mixture leaned, especially on hot days. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So its important to remember that the power produced by the engine is not a straight linear calculation. When you did your comment:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But why the RPM is more and the BHP is only 75%? If I consider 2500RPM =110BHP then at 2400 it should be 105.6BHP which is 96% of total BHP&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You assumed that the engine can produce power at 10RPM, which just isn't true. Lets take a better example and say that at 1600 RPM it is producing 25HP and at 2600 it produces 100HP, we can do the math then.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using a linear interpolation formula this gives us 85HP which the graph tells us is 80 HP. Remember though, the graph is curved, and linear interpolation is, well, linear.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-03-15T16:00:12.710" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26183" PostTypeId="1" CreationDate="2016-03-15T16:17:05.320" Score="7" ViewCount="906" Body="&lt;p&gt;When is it safe to land a Cessna-172 after a commercial airline jet has landed? &lt;/p&gt;&#xA;" OwnerUserId="14020" LastEditorUserId="19" LastEditDate="2016-06-28T16:20:03.553" LastActivityDate="2021-02-13T00:42:18.030" Title="What is the safe separation for landing a Cessna-172 behind a commercial airline jet?" Tags="&lt;cessna-172&gt;&lt;wake-turbulence&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26184" PostTypeId="2" ParentId="26183" CreationDate="2016-03-15T16:40:41.783" Score="11" Body="&lt;p&gt;It depends on the size of the preceding aircraft. &lt;a href=&quot;http://code7700.com/pdfs/icao_doc_4444_15th_edition.pdf&quot; rel=&quot;noreferrer&quot;&gt;ICAO PANS-ATM-Doc 4444 Air Traffic Management&lt;/a&gt; has some values.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;5.8.2 · Arriving aircraft&lt;/p&gt;&#xA;&lt;p&gt;5.8.2.1 Except as provided for in 5.8.l.l a) and b), the following separation minima shall be applied.&lt;/p&gt;&#xA;&lt;p&gt;5.8.2.l.l The following minima shall be applied to aircraft landing behind a HEAVY or a MEDIUM aircraft:&lt;/p&gt;&#xA;&lt;p&gt;a) MEDIUM aircraft behind HEAVY aircraft- 2 minutes;&lt;/p&gt;&#xA;&lt;p&gt;b) LIGHT aircraft behind a HEAVY or MEDIUM aircraft- 3 minutes.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Note that in case of A380, it is more- 4 minutes.&lt;/p&gt;&#xA;&lt;p&gt;In case of distances, the light aircraft are to be landed 5nm after a medium aircraft, 6nm after a heavy and 8nm after A380.&lt;/p&gt;&#xA;&lt;p&gt;Note: The categorisation of aircraft is done as below:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;4.9.1 Wake turbulence categories of aircraft&lt;/p&gt;&#xA;&lt;p&gt;4.9.1.1 Wake turbulence separation minima shall be based on a grouping of aircraft types into three categories according to the maximum certificated take-off mass as follows:&lt;/p&gt;&#xA;&lt;p&gt;a) HEAVY (H)- all aircraft types of 136 000 kg or more;&lt;/p&gt;&#xA;&lt;p&gt;b) MEDIUM (M)- aircraft types less than 136 000 kg but more than 7 000 kg; and&lt;/p&gt;&#xA;&lt;p&gt;c) LIGHT (L)- aircraft types of 7 000 kg or less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-15T16:40:41.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26185" PostTypeId="1" CreationDate="2016-03-15T17:24:15.373" Score="12" ViewCount="2898" Body="&lt;p&gt;When you're departing from an airport within controlled airspace, when should you contact ATC?  This is when the airport you were departing from is non-towered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario: I am departing a non-towered airport in class Charlie airspace. I need to request VFR flight following to another airport. When do I contact ATC?&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="62" LastEditDate="2017-08-18T13:38:24.450" LastActivityDate="2017-08-18T13:38:24.450" Title="When do you contact ATC when departing from a non-towered airport into class C controlled airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26186" PostTypeId="2" ParentId="26185" CreationDate="2016-03-15T17:40:55.853" Score="11" Body="&lt;p&gt;This is spelled out clearly in &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.130&quot;&gt;CFR 91.130&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Communications. Each person operating an aircraft in Class C airspace must meet the following two-way radio communications requirements:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Arrival or through flight. Each person must establish two-way radio communications with the ATC facility (including foreign ATC in the case of foreign airspace designated in the United States) providing air traffic services prior to entering that airspace and thereafter maintain those communications while within that airspace.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Departing flight. Each person—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; (i) From the primary airport or satellite airport with an operating control tower must establish and maintain two-way radio communications with the control tower, and thereafter as instructed by ATC while operating in the Class C airspace area; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; (ii) &lt;strong&gt;From a satellite airport without an operating control tower, must establish and maintain two-way radio communications with the ATC  facility having jurisdiction over the Class C airspace area as soon as practicable after departing.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can try contacting them while on the ground, but if you can't raise them, you have to do it as soon as you can after take-off.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-03-15T17:40:55.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26187" PostTypeId="1" AcceptedAnswerId="26208" CreationDate="2016-03-15T19:12:58.400" Score="4" ViewCount="804" Body="&lt;p&gt;If they carry a lot of weight inside, what avoids them from falling down to the passenger's heads? What holds them? How are they mounted inside the cabin?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-15T21:12:11.757" LastActivityDate="2016-03-16T13:40:17.127" Title="What holds the overhead lockers?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26189" PostTypeId="2" ParentId="21240" CreationDate="2016-03-15T19:56:24.810" Score="6" Body="&lt;p&gt;First of all, the L-1011 had a fourth hydraulic system compared to the DC-10/MD-11 which only had three.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Secondly, the L-1011 was a fantastic aircraft which had design input from Kelly Johnson, the man who brought us the SR 71 Blackbird and the F-104 Star Fighter. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The L-1011 was by far the superior aircraft and had capabilities that have since only been met for an aircraft of its size by the 777. It could even land itself. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What hurt the L-1011 was the financial failure of Rolls Royce that delayed the aircraft's entry into the market by a year. It never recovered from the orders lost to the DC-10 by AA and United who were desperate to get a tri-jet into their fleets. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engines couldn't be changed because the Rolls Royce RB-211 was specifically designed for the L-1011's center engine housing and nothing else would fit, and there wasn't time for a redesign, retest, and re-certification. Fortunately the British government bailed out Rolls Royce so that the engines were eventually built and delivered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final straw for the DC-10 was the crash in Chicago, though technically an AA maintenance failure, the DC-10 was poorly designed and rushed into the marketplace to take advantage of the L-1011's delay. Not another DC-10 was ordered after that incident, and the MD-11 was simply a repackaged version of the same problem aircraft, made of composite materials and more fuel efficient or so everyone thought until it went into service. Another white elephant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Standard on the Tri-Star was a co-pilot stick shaker, an extra cost option on the DC-10, as well as automatic electrical bus relays which transferred load from a dead engine to a live one, standard on the L-1011 and an option on DC-10, and finally the front slats on the L-10 mechanically locked into place once hydraulically extended, something not offered on the DC-10, which is why AA 191 crashed. Had this been an L-1011, that accident would not have occurred.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The final death knell for the Tri-Star was that Lockheed simply wanted out of the commercial aircraft marketplace so that it could focus on military contracts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing had no reason to offer a Tri-jet as it developed the long and short versions of the 747. In fact, the Tri-jets were a design competition between Douglas and Lockheed based on American Airlines criteria which initially ordered the L-10, but switched to the DC-10 after Rolls Royce went into bankruptcy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the 727, never intended to be more than it was, an aircraft capable of short ETOPS, mostly to the Caribbean or Hawaii.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ask any pilot who had flown both the Tri-Star and the DC-10 as to which he preferred and you'll find that almost all will pick the Lockheed.&lt;/p&gt;&#xA;" OwnerUserId="14023" LastActivityDate="2016-03-15T19:56:24.810" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26190" PostTypeId="1" CreationDate="2016-03-15T20:08:45.353" Score="0" ViewCount="615" Body="&lt;p&gt;I was just watching scenes from Final Countdown movie and this little stringy bit caught my attention. Anyone knows what it is and what is its purpose? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=1SwgU42XSpw&quot; rel=&quot;nofollow noreferrer&quot;&gt;Here is the video I saw it in.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QWZpJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QWZpJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3562" LastActivityDate="2016-03-15T20:08:45.353" Title="What is this &quot;string&quot; in front of canopy of F-14" Tags="&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2016-03-15T20:32:43.000" ContentLicense="CC BY-SA 3.0" />
  <row Id="26191" PostTypeId="6" CreationDate="2016-03-15T21:07:08.777" Score="0" Body="&lt;p&gt;OK, I'm running because you're all well-behaved enough for me to put up with!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've been a moderator during the beta so most folks voting in the election are probably familiar with my moderation style: I subscribe to the &quot;moderators are janitors&quot; theory:&lt;br&gt;&#xA;We're here to handle the exceptional messes (spam, blatantly off-topic posts, personal flame wars, mile-long comment threads, and the like) and keep the muck off the floors so the community can function. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am not a fan of &quot;mod-hammering&quot; posts as a unilateral action because autocratic moderation doesn't scale well: In all but the most blatant situations I prefer to let the community handle things on its own (perhaps with the occasional prod in comments, &lt;a href=&quot;http://chat.stackexchange.com/rooms/12036/the-hangar&quot;&gt;chat&lt;/a&gt;, or &lt;a href=&quot;http://meta.aviation.stackexchange.com&quot;&gt;meta&lt;/a&gt; to start or steer the discussion), or at least show the beginnings of a consensus before tacking action.&lt;br&gt;&#xA;My ultimate goal in doing so is to help create a self-moderating environment where the high-reputation users vote, close, and curate content actively as we grow to maintain and improve the quality of the site (basically &quot;A site where things work as designed!&quot;).&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="64" LastEditDate="2016-03-15T21:07:08.777" LastActivityDate="2016-03-15T21:07:08.777" CommentCount="1" CommunityOwnedDate="2016-03-15T21:07:08.777" ContentLicense="CC BY-SA 3.0" />
  <row Id="26193" PostTypeId="6" CreationDate="2016-03-16T02:18:01.470" Score="0" Body="&lt;h2&gt;Why me?&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I have been active on the site since a few days after public beta began.&lt;/li&gt;&#xA;&lt;li&gt;I am a moderator on another stack exchange site, so I know the ropes.&lt;/li&gt;&#xA;&lt;li&gt;I fully subscribe to the &lt;a href=&quot;http://blog.stackoverflow.com/2009/05/a-theory-of-moderation&quot;&gt;theory of moderation&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;I keep an eye on meta and have been an active participant.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h2&gt;Why not me?&lt;/h2&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I haven't been the most active reviewer, editor or flagger.&lt;/li&gt;&#xA;&lt;li&gt;I just started a full time job so while I can commit to being an active moderator, I won't be as active as I have been in the past.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I see my role as a diamond moderator to clean up messes and deal with the few issues on the SE network that community moderators cannot.  I don't wield the mod-hammer on anything the community is capable of taking care of.  I handle flags as soon as I see them.  I communicate with my fellow mods to make sure we are on the same page.  &lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2016-03-16T02:18:01.470" LastActivityDate="2016-03-16T02:18:01.470" CommentCount="1" CommunityOwnedDate="2016-03-16T02:18:01.470" ContentLicense="CC BY-SA 3.0" />
  <row Id="26196" PostTypeId="1" CreationDate="2016-03-16T07:37:05.027" Score="16" ViewCount="5925" Body="&lt;p&gt;Why don't in-flight entertainment systems have the capability to connect to our own devices and play movies? Or why don't they have arena gaming?&#xA;Are there any regulations that prevent engineers from designing innovative in-flight entertainment systems? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, what factors come into play - regulations, cost, weight, complexity?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="2633" LastEditDate="2016-03-16T15:12:50.917" LastActivityDate="2016-03-17T12:06:15.570" Title="Why are in-flight entertainment systems not very evolved?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26197" PostTypeId="2" ParentId="26196" CreationDate="2016-03-16T11:22:09.080" Score="29" Body="&lt;ol&gt;&#xA;&lt;li&gt;It's expensive. If you wanted to build something like an XBox or Playstation into each seat,  you're talking about an absolute minimum of \$300 per seat (\$60,000 for a small-ish aircraft like a 737, \$160,000 for a typical A380, and probably much more). While that doesn't sound like a lot on the price of an airliner, it certainly adds up over a fleet of hundreds of aircraft... all of which means you have to add to the ticket price and become less competitive. And that's just talking about gaming.&lt;/li&gt;&#xA;&lt;li&gt;Safety/security. Allowing the passengers to connect to the system, no matter how well designed, is a potential security hole. This can be avoided to some extent if you &lt;strong&gt;completely&lt;/strong&gt; separate the systems, but there's always potential for someone to find a loophole you didn't think of (overloading the in-flight entertainment and messing up the electrical power, for example). Dealing with this would add significantly to the cost above.&lt;/li&gt;&#xA;&lt;li&gt;There isn't much need to. Most people who fly are either happy with the in-flight movie choices, or bring their own iPad/Kindle etc.&lt;/li&gt;&#xA;&lt;li&gt;While using Airplay to send movies from your iPad to your TV works pretty well for one or two devices at home... it quickly falls apart when you're trying to make a wireless network capable of handling 200-800 streams at once!&lt;/li&gt;&#xA;&lt;li&gt;General safety concerns: despite the fact that we're now fairly confident that having electrical devices &lt;strong&gt;on&lt;/strong&gt; with their WiFi/Bluetooth/4G &lt;strong&gt;off&lt;/strong&gt; is safe, to send the movies they'd need to turn WiFi or similar &lt;strong&gt;on&lt;/strong&gt;, which is a potential risk&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In short it's a lot of risk and cost, for not much reward. If you have an iPad with you, why do you need to send the movie to the TV screen in front of you? You can just watch it on the iPad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note also that some airlines do have some basic multiplayer gaming built into the IFE: although it's more &quot;Connect 4&quot; than &quot;Battlefield 4&quot;&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-03-16T11:22:09.080" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26198" PostTypeId="1" AcceptedAnswerId="26199" CreationDate="2016-03-16T11:42:57.750" Score="23" ViewCount="5744" Body="&lt;p&gt;I know that while in-flight the electricity is produced by the engines. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens if every possible system requiring electricity is in the &lt;code&gt;on&lt;/code&gt; state? This should require extra electricity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does this usage of electricity increase the fuel consumption by any means?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;*Edit to include the additional question from the comments section:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that the engines require fuel to produce electricity how big is the impact on fuel consumption, speaking of &quot;mainstream&quot; airliners like the A320?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;" OwnerUserId="11787" LastEditorUserId="11787" LastEditDate="2016-03-17T15:51:39.110" LastActivityDate="2016-03-18T10:42:48.080" Title="Does electrical usage contribute to fuel consumption?" Tags="&lt;airliner&gt;&lt;fuel&gt;&lt;electrical-system&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26199" PostTypeId="2" ParentId="26198" CreationDate="2016-03-16T11:45:28.887" Score="31" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight, unless you use external energy sources like the Sun, each change in the use of electricity leads to a proportional change in the quantity of fuel burnt in the engines (or in the APU).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On an aircraft, generators only convert fuel potential chemical energy into something else, usually electricity, hydraulic energy or pneumatic energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no other source of energy:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The batteries themselves need to be charged, charging burns fuel.&lt;/li&gt;&#xA;&lt;li&gt;The RAT (&lt;a href=&quot;https://aviation.stackexchange.com/questions/7702/where-can-i-get-a-high-res-photo-of-the-rat-from-an-a320-airbus&quot;&gt;ram air turbine&lt;/a&gt;) uses energy from the relative wind created by the engines thrust. If the RAT is used because the engines and the APU are down, the relative wind is due to the loss of altitude created by the gravity. This kinetic energy is the restitution of the &lt;a href=&quot;http://buildingontheword.org/wp-content/uploads/2015/02/mousetrap.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;potential energy&lt;/a&gt; accumulated during the climb with the engines, so with fuel.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Details&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Maximum power of the electrical equipment&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electrical power needs of the whole aircraft can be completely met by a single engine generator, or by the APU. On the A320 family, the APU is an &lt;a href=&quot;https://hsapps.utc.com/powersystems/products/aps3200pds.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;APS3200&lt;/a&gt; delivering about 90 kVA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;APU fuel consumption&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From this &lt;a href=&quot;http://www.pprune.org/tech-log/381639-a320-apu-average-hour-fuel-burn.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;PPRuNE&lt;/a&gt; discussion, an A320 APU may consume 130 kg per hour on the ground, and 51 kg per hour at FL300. However the APU provides at the same time electricity and bleed air energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;APU fuel consumption for electrical energy generation&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However the fuel quantity used for the sole electricity generation may be approximated:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Maximum power required by the aircraft equipment → 90 kVA AC.&lt;/li&gt;&#xA;&lt;li&gt;Assuming a mean cos φ = 0.8 → Apparent power = 110 kW DC.&lt;/li&gt;&#xA;&lt;li&gt;Assuming 25% efficiency for the system (gas turbine + generator) → Fuel power required 440 kW.&lt;/li&gt;&#xA;&lt;li&gt;Fuel energy required → 440 kWh per hour.&lt;/li&gt;&#xA;&lt;li&gt;Converting to joules (1 MJ = 0.28 kWh) → 440 kWh ≈ 1,570 MJ.&lt;/li&gt;&#xA;&lt;li&gt;Kerosene specific energy = 43 MJ/kg → Fuel quantity burnt in an hour = 1,570 / 43 = 36 kg (45 L)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So approximately 36 kg of fuel are required per hour to provide for electric energy on an A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that in flight all engines generators will be active and will share the total demand (feeding different buses for safety), and the APU will likely be inactive. The fuel consumption should be more or less the same, regardless of the number and nature of the active generators. An inactive or unloaded engine generator can be seen as not impacting the fuel consumption for practical purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Engines burning the maximum rate of fuel&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines have a maximal power. When the engines are already at full thrust, increasing the electric load will divert an additional amount of energy to the generator. This quantity being removed from the energy usable for aircraft propulsion, the aircraft will slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(Updated, taking into account the multiple helpful comments -- Thanks!)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bonus&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Breathing increases fuel use too:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Each time a passenger breathes, they reject heat and CO2 which must be evacuated out of the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Some quantity of air must be replaced by new air by the conditioning system.&lt;/li&gt;&#xA;&lt;li&gt;This system uses pneumatic or electric energy, and again fuel must be burnt to create this energy.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-03-17T22:10:35.050" CommentCount="16" ContentLicense="CC BY-SA 3.0" />
  <row Id="26200" PostTypeId="2" ParentId="26198" CreationDate="2016-03-16T12:26:00.063" Score="10" Body="&lt;p&gt;It is just not possible otherwise but the effect should be somewhat below 10 % even when maximal amounts of electricity are consumed. Much more power is required and consumed just to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A generator axis must rotate in order to produce electricity, and the resistance to rotate is proportional to the generator load (when the generator is not loaded, only friction remains). That's physics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine that is coupled to the generator will meet more resistance and should consume more fuel when powerful energy consumers are connected to the generator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However if the A320 generator requires 90 kW (as from another question), it does not make significant part of the engine power. An engine of 747 produces 16275 Kw and even turboprop engines are rated of the order of a few thousand kW (3,362 kW for C-130 &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20070307224501AAVhueG&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;), so the generator is unlikely to have significant impact on the power produced even when running at the full load.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-03-18T10:42:48.080" LastActivityDate="2016-03-18T10:42:48.080" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26201" PostTypeId="2" ParentId="26198" CreationDate="2016-03-16T12:34:58.770" Score="21" Body="&lt;p&gt;Yes, because (like a car for example), the aircraft is a closed system, and all energy must be provided internally.&#xA;So, in flight, that energy must come from the engines, and therefore, the engine must either slow down, or use more fuel.&lt;/p&gt;&#xA;" OwnerUserId="14035" LastActivityDate="2016-03-16T12:34:58.770" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="26202" PostTypeId="2" ParentId="26161" CreationDate="2016-03-16T12:39:51.783" Score="4" Body="&lt;p&gt;Double glazing.&#xA;The gap in between the panes has very little moisture in it, so there is nothing to condense on the outside pane.&#xA;There is no condensation on the inside pane because of the temperature gradient between the panes.&lt;/p&gt;&#xA;" OwnerUserId="14035" LastActivityDate="2016-03-16T12:39:51.783" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26203" PostTypeId="1" CreationDate="2016-03-16T13:04:06.297" Score="5" ViewCount="443" Body="&lt;p&gt;I have wingtip landing/taxi lights on my plane.  They have acrylic covers to protect the bulbs.  They have started to haze over time, similar to the effect of car headlights.  I am wondering if anyone has experienced this and can provide information on how to correct this issue.  I feel as if this might be affecting the ability of the bulbs to direct light on the runway/taxiway efficiently.  I am starting to eye some of the cleaners that say they can correct this in the automotive aisle, however I am very hesitant.  I don't want to buy new covers, as I am sure there is a better/cheaper option.&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="19" LastEditDate="2016-06-28T16:15:13.140" LastActivityDate="2016-06-28T16:15:13.140" Title="Wingtip landing light lenses are hazed - what can I do to make them clear again?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-lighting&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26204" PostTypeId="2" ParentId="26196" CreationDate="2016-03-16T13:10:05.397" Score="4" Body="&lt;p&gt;Because there's no need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In-flight entertainment screens are generally the size of a large phone, and definitely smaller than a tablet.  Resolution is &lt;em&gt;always&lt;/em&gt; worse, because in-flight entertainment screens don't get replaced as often as consumer electronics.  And the audio circuit is nothing to write home about either.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's measurably worse in every way, compared to a phone or tablet capable of storing and playing video.  Other answers have described the amount of work needed to make it happen, for something which gives customers nothing of benefit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simple as that, really.&lt;/p&gt;&#xA;" OwnerUserId="12155" LastActivityDate="2016-03-16T13:10:05.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26207" PostTypeId="1" CreationDate="2016-03-16T13:39:44.330" Score="3" ViewCount="447" Body="&lt;p&gt;Is it a requirement to record/maintain flight hours for serialized A/C parts? I have searched the FAA website with no luck.&lt;/p&gt;&#xA;" OwnerUserId="14036" LastEditorUserId="12623" LastEditDate="2016-03-16T13:41:37.030" LastActivityDate="2016-03-16T15:03:01.163" Title="Are you required to record flight hours of serialized parts?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26208" PostTypeId="2" ParentId="26187" CreationDate="2016-03-16T13:40:17.127" Score="6" Body="&lt;p&gt;The overhead bins are usually mounted to the aircraft structure. For example, in case of Boeing 737, they are mounted to the stingers using tie rods. From an &lt;a href=&quot;http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/Kegworth/AAIB/COPY/gobmerep.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;accident report of Boeing 737-400&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The forward inertial load is reacted by a diagonal tie, mounted at one end to stringer 6 or 7 in the fuselage crown and at the other end to a fitting on the upper surface of the bin. The vertical and lateral loads are reacted by short tie rods attached to the fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y3Z6z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y3Z6z.jpg&quot; alt=&quot;737 overhead bin&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B737-400 overhead bin attachment. Image from the &lt;a href=&quot;http://www.rvs.uni-bielefeld.de/publications/Incidents/DOCS/ComAndRep/Kegworth/AAIB/COPY/gobmerep.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;same report&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-16T13:40:17.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26209" PostTypeId="2" ParentId="26169" CreationDate="2016-03-16T14:05:29.817" Score="14" Body="&lt;h2&gt;You should wash your aircraft in accordance with the manufacturer's instructions.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;We could all offer opinions and product recommendations in response to this question. However, the best answer is: in accordance with the manufacturer's instructions. Since you ask the question generically, without any information on what aircraft you might have, I will answer generically.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your manufacturer's instructions can generally be found in at least two places: the owner's manual/AFM and the maintenance manual. For example, in the owners manual for a 1975 Cessna 172M, you will find &lt;em&gt;Section V: Care of The Airplane&lt;/em&gt; containing instructions on how to wash painted surfaces, bare aluminum surfaces, interior surfaces, and the windscreen and windows. The maintenance manual for the same aircraft contains nearly—if not exactly—identical information in chapter 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, for that aircraft and others, Cessna recommends use of &lt;em&gt;mild detergent&lt;/em&gt; in certain applications; you might not find that overly helpful in choosing &lt;em&gt;what&lt;/em&gt; to use. Based on my research and experience, and time honored practice that I've observed, Dawn dish soap is widely used for cleaning painted Cessna aircraft with no apparent long term harmful effects. The airframe that I fly for work has tens of thousands of hours on it, and while I cannot vouch for how often it was washed in the past, I try to wash parts of it a few times a week. There is no apparent washing damage to the paint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will also highlight Cessna's instruction to use Stoddard solvent on areas of stubborn oil or grease; this can be especially helpful in cleaning the belly with it's typical collection of oil and dirt. My practice is typically to wipe down the belly with solvent first, and then follow with a water and detergent wash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the manufacturer's instructions are not clear, or are otherwise insufficient to answer your question regarding your specific aircraft, I would recommend asking your maintenance professional. He or she should have both the knowledge and experience to steer you in the right direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For more insight into the world of aircraft cleaning, and especially for the specific product recommendations you want, you might take a look at this AvWeb article by Kim Santerre: &lt;a href=&quot;http://www.avweb.com/news/maint/192152-1.html&quot; rel=&quot;noreferrer&quot;&gt;Aircraft Cleaning&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-20T16:04:42.220" LastActivityDate="2016-03-20T16:04:42.220" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26211" PostTypeId="2" ParentId="26207" CreationDate="2016-03-16T15:02:22.427" Score="2" Body="&lt;p&gt;Short answer: only for the airframe, engines, propellors and rotors (as applicable).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2009/lifelimparts%20-%20(2009)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow&quot;&gt;This legal interpretation&lt;/a&gt; is a response to someone who asked which records are required to identify when life-limited parts need to be replaced. It says that you're only required to keep flight time records of the airframe, engine(s), propellor(s) and rotor(s), as appropriate:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Existing regulations, specifically &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1417&quot; rel=&quot;nofollow&quot;&gt;14 C.F.R. § 91.417(a)(2)(i)&lt;/a&gt;, require&#xA;  each owner or operator to keep records containing the total time in&#xA;  service of the airframe, each engine, each propeller, and each rotor.&#xA;  This is accomplished by the owner or operator recording and tracking&#xA;  in some form and manner the time in service of the airframe,&#xA;  engines(s), propeller(s), and rotor(s) from the moment the aircraft&#xA;  leaves the surface of the earth until it touches it at the next point&#xA;  of landing, as referenced in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot; rel=&quot;nofollow&quot;&gt;14 C.F.R. § 1.1&lt;/a&gt;. In addition, §&#xA;  91.417(a)(2)(ii), and similar provisions in 14 C.F.R. §§ 121.380(a)(2)(iii) and 135.439(a)(2)(ii), require owners or operators (certificate holders) to keep records that show the current status of&#xA;  life-limited parts of each airframe, engine, propeller, rotor, and&#xA;  appliance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;91.417 does indeed say - among other things - that owners and operators have to record the time in service and status for the airframe, engines, props and rotors, but only the status for life-limited &quot;appliances&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) Records containing the following information:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) The total time in service of the airframe, each engine, each&#xA;  propeller, and each rotor.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) The current status of life-limited parts of each airframe,&#xA;  engine, propeller, rotor, and appliance.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;1.1. defines &quot;time in service&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Time in service&lt;/em&gt;, with respect to maintenance time records, means the&#xA;  time from the moment an aircraft leaves the surface of the earth until&#xA;  it touches it at the next point of landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=pt14.1.43#se14.1.43_110&quot; rel=&quot;nofollow&quot;&gt;43.10&lt;/a&gt; defines &quot;life-limited parts&quot;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Life-limited part&lt;/em&gt; means any part for which a mandatory replacement&#xA;  limit is specified in the type design, the Instructions for Continued&#xA;  Airworthiness, or the maintenance manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;To summarize:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;You only need to record service time for the airframe, engine, props and rotors&lt;/li&gt;&#xA;&lt;li&gt;For any other life-limited parts, you only need to record their status, i.e. you need to be able to say when it's time to replace them&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-16T15:02:22.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26212" PostTypeId="2" ParentId="26207" CreationDate="2016-03-16T15:03:01.163" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.417&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.417&lt;/a&gt;(a)(2) States:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(2) Records containing the following information:&lt;/p&gt;&#xA;&lt;p&gt;  (i) The total time in service of the &lt;strong&gt;airframe, each engine, each propeller, and each rotor&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;  (ii) The current status of life-limited parts of each airframe, engine, propeller, rotor, and appliance.&lt;/p&gt;&#xA;&lt;p&gt;  (iii) The time since last overhaul of all items installed on the aircraft which are required to be overhauled on a specified time basis.&lt;/p&gt;&#xA;&lt;p&gt;  (iv) The current inspection status of the aircraft, including the time since the last inspection required by the inspection program under which the aircraft and its appliances are maintained.&lt;/p&gt;&#xA;&lt;p&gt;  (v) The current status of applicable airworthiness directives (AD) and safety directives including, for each, the method of compliance, the AD or safety directive number and revision date. If the AD or safety directive involves recurring action, the time and date when the next action is required.&lt;/p&gt;&#xA;&lt;p&gt;  (vi) Copies of the forms prescribed by§ 43.9(d) of this chapter for each major alteration to the airframe and currently installed engines, rotors, propellers, and appliances.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In addition, if you read closely (a)(2)(ii) requires you to keep records of any &lt;strong&gt;life limited parts&lt;/strong&gt; which means that if the manufacturer identifies it to be &amp;quot;life-limited&amp;quot;, like a gearbox, then the status for that must be recorded as well, with some exceptions for the time being included in other life-limited recordings.&lt;/p&gt;&#xA;&lt;p&gt;How do you know if it is life-limited? You need to read the Type Certificate Data Sheet, Airworthiness Directives, or Limitations of FAA approved manuals. Its also useful to note that while you certainly can keep copies of records in computerized form, the FAA requires paper records mostly because there is a signature requirement that is not satisfied by electronic signatures.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-16T15:03:01.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26213" PostTypeId="2" ParentId="26196" CreationDate="2016-03-16T15:14:15.647" Score="16" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why don't in-flight entertainment systems have the capability to connect to our own devices and play movies?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The answer is that they do. These are actually quite common in the U.S. and many other parts of the world and have been so for at least a few years now. All of Delta's recently-acquired or upgraded interiors on anything 737/A320 size and up have this, for example. Most of Cathay Pacific's fleet and, IIRC, all of Korean Air's fleet also had IFE systems to which you could connect your phone or tablet (via USB.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as the Wi-Fi concerns mentioned in another answer, much of the world does not have any problem with Wi-Fi or Bluetooth being enabled during flight. Nearly all major U.S. airlines offer Wi-Fi during flight and some of them even provide it gate-to-gate (that is, including taxi, takeoff, and landing.) Most of them offer streaming media (movies, TV shows, and even streaming live TV) over the Wi-Fi that you can watch on your own device. On Southwest Airlines, this is actually their sole form of IFE service. There are no screens in the seatbacks; you just use your own, which is almost certainly better quality anyway. Another benefit of this approach is that airlines don't need to constantly upgrade their IFE systems, as passengers will effectively do that for them when they buy new phones/tablets/laptops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There do exist a few jurisdictions around the world where Wi-Fi/Bluetooth are still not allowed during flight, but these seem to be a minority now.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any regulations that prevent engineers from designing innovative in-flight entertainment systems?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are no regulations banning them, but there are lots of regulations that make them expensive to design, test, and certify for flight (as with anything else that is installed on an airplane.) To underscore just how expensive new IFE system testing can be, GoGo (a major in-flight Wi-Fi provider) &lt;a href=&quot;http://concourse.gogoair.com/inside-gogo/2ku-fastestinflight/my-office-in-the-sky-jimmy-ray-n321gg&quot;&gt;actually has their own 737-500&lt;/a&gt; (registration &lt;a href=&quot;https://www.planespotters.net/airframe/Boeing/737/26445/N321GG-Gogo&quot;&gt;N321GG&lt;/a&gt;) that is used for nothing but testing their in-flight Wi-Fi systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even once the design, testing, and certification are done, it's expensive to take the airplane out of service long enough to install the new interior. Keep in mind that most airliners will be generating hundreds of thousands of dollars in revenue per day (although much less in profit, of course.) Roll-outs for new equipment will generally be multi-year processes for large airlines just due to the shear number of airplanes that must be modified and that fact that you can only take a few out of service at any given time if you want to keep your airline operational.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="998" LastEditDate="2016-03-16T16:59:21.040" LastActivityDate="2016-03-16T16:59:21.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26215" PostTypeId="2" ParentId="26203" CreationDate="2016-03-16T15:22:28.437" Score="2" Body="&lt;p&gt;The hazing is a collection of very small scratches on the acrylic, and the way to remove them is to actually remove a thin layer of the acrylic - the trick is to make sure you use something that won't damage any of the paint/metal around the cover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mild acrylic polish is your best bet, although any mild abrasive will work (including non-&quot;sensitive&quot; toothpaste and a paper towel... although it might take a while!). There are plenty of &quot;Perspex cleaner&quot; style products for a reasonable price to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use a small amount (multiple small applications are better for controlling the spread) and try to use a thicker &quot;paste&quot; type of abrasive rather than a runnier one, for the same reason. Apply a small amount and some fairly firm pressure with a cloth, as per the instructions of the cleaner, removing any excess regularly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think there are deeper scratches than just a very fine &quot;hazing&quot; on the lens, you can use a fine sandpaper (eg 1600 grit) to sand the acrylic first before using the polish&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-03-16T15:22:28.437" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26216" PostTypeId="1" CreationDate="2016-03-16T15:56:23.053" Score="3" ViewCount="643" Body="&lt;p&gt;What's the definition and the meaning of &quot;soft dirt runway&quot;? You can read that expression in the following text:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;..The aircraft's rolling resistance, μ, is determined by the type of&#xA;  runway surface and by the type, number, inflation pressure and&#xA;  arrangement of the tires. A thin, high-pressure tire operated over a&#xA;  soft dirt runway will have so much rolling resistance that the&#xA;  aircraft may be unable to move. A large, low pressure tire can&#xA;  operate over a softer runway surface but will have more aerodynamic&#xA;  drag if not retracted, or will take up more room if retracted. Values&#xA;  of μ for different runway surfaces are provided in the detailed&#xA;  takeoff analysis in Chapter 17. ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/1600869114&quot; rel=&quot;nofollow&quot;&gt;Daniel P. Raymer, &lt;em&gt;Aircraft design: a conceptual approach&lt;/em&gt;&lt;/a&gt;. Chapter 5 &lt;em&gt;Thrust-to-weight ratio and wing loading&lt;/em&gt;, paragraph 5.3 &lt;em&gt;Wing Loading&lt;/em&gt;, sub-paragraph &lt;em&gt;Takeoff Distance&lt;/em&gt;, page 88.&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="62" LastEditDate="2016-03-16T17:27:59.540" LastActivityDate="2016-03-16T22:33:02.243" Title="What's the definition and the meaning of “soft dirt runway”?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;airport&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26217" PostTypeId="1" AcceptedAnswerId="26249" CreationDate="2016-03-16T16:11:08.360" Score="7" ViewCount="1205" Body="&lt;p&gt;Commercial aircraft are equipped with &lt;a href=&quot;//aviation.stackexchange.com/q/1583/1696&quot;&gt;ram air turbines&lt;/a&gt; that can be deploy to provide power in case all other sources of power are lost. Ram air turbines have the benefit of providing power as long as the aircraft is moving through the air. However, aircraft are almost always designed with internal generators, driven off of the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a limited case of &lt;a href=&quot;//aviation.stackexchange.com/q/16005/1696&quot;&gt;adding generators to older aircraft&lt;/a&gt;. But they are also used to power large accessories, &lt;a href=&quot;//aviation.stackexchange.com/q/25835/1696&quot;&gt;like the jamming pods on the EA-18 Growler&lt;/a&gt;. The EA-6B, which the Growler replaced, was also a modified attack aircraft using jamming pods with ram air turbines. Larger aircraft that are modified for the electronic warfare role don't seem to go this route though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously the turbine will add drag, and it seems like internal generators are more efficient, since almost all aircraft are designed to generate power that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: what are the benefits or drawbacks of using ram air turbines to generate power? While they are generally saved for emergencies, what makes them more useful in cases like jamming pods, compared to other options?&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-12-07T20:35:05.947" LastActivityDate="2016-12-07T20:35:05.947" Title="What are the pros/cons of ram air turbines?" Tags="&lt;electrical-system&gt;&lt;rat&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26218" PostTypeId="2" ParentId="26217" CreationDate="2016-03-16T17:07:11.813" Score="5" Body="&lt;p&gt;You have kind of answered your own question. The down side to ram air turbines is they cause drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The up side is that they provide power outside the internal generating capacity of the aircraft (e.g., in emergencies when there is no power).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case a of a jamming pod, having its own power source eliminates/reduces the need to rely on internal power. That makes the pod modular. If the pod did not generate its own power, there would need to be a generator inside that sits there regardless of whether the pod were attached.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-03-16T17:07:11.813" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26219" PostTypeId="2" ParentId="26217" CreationDate="2016-03-16T17:57:20.767" Score="0" Body="&lt;p&gt;Another advantage to a RAT as opposed to using the engine powered generator is that it reduces the requirement for bleed air so the engines can be more efficient and responsive.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-16T17:57:20.767" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26220" PostTypeId="1" CreationDate="2016-03-16T18:36:01.243" Score="6" ViewCount="549" Body="&lt;p&gt;Currently I am a student pilot in Spain (Barcelona) and I am 2 days away from my solo. I wanted to ask if there is any good application that will help me on VFR navigation since I'm allowed to go to all Barcelona in my solo, but I am afraid if I get lost I see my self weak in VFR flights and specially to locate my position so any good app in the iPhone device that will help me in navigation because I want to visit the whole Barcelona and not just staying at places that I know because I will get bored for sure.&lt;/p&gt;&#xA;" OwnerUserId="12552" LastEditorUserId="1696" LastEditDate="2016-03-18T14:33:18.517" LastActivityDate="2016-03-18T14:33:18.517" Title="What are good apps to help with VFR navigation on my first solo?" Tags="&lt;flight-training&gt;&lt;navigation&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="26221" PostTypeId="2" ParentId="26196" CreationDate="2016-03-16T18:41:46.560" Score="2" Body="&lt;p&gt;I refer you to&#xA;&lt;a href=&quot;https://en.wikipedia.org/wiki/Swissair_Flight_111&quot; rel=&quot;nofollow noreferrer&quot;&gt;Swiss Air Flight 111&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;At that point in the investigation, the crash was generally believed to have been caused by faulty wiring in the cockpit after the entertainment system in the plane started to overheat.&lt;/p&gt;&#xA;&lt;p&gt;Investigators identified evidence of arcing in wiring of the in-flight entertainment system network&lt;/p&gt;&#xA;&lt;p&gt;The TSB made nine recommendations relating to changes in aircraft materials (testing, certification, inspection, and maintenance), electrical systems, and flight data capture&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;As a result of incidents like Flight 111, new entertainment systems must be tested, certified, inspected, and maintained - which is going to slow down innovation.  Most passengers have tablets, laptops, etc.&lt;/p&gt;&#xA;" OwnerUserId="3830" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-16T18:41:46.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26222" PostTypeId="1" AcceptedAnswerId="26229" CreationDate="2016-03-16T19:23:45.023" Score="2" ViewCount="263" Body="&lt;p&gt;I'm looking for a way to simulate airfoils used to reduce turbulence.&#xA;airfoiltools.com already does this a long way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However I have width and length limits, and I'm interested in comparing full profiles with profiles that are virtually longer but cut where the trailing end meets the boundary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can CAESES or SimFlow do this without too steep learning curve? (I'm a complete newbie.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Specifics: Chord 30 cm, width 25-30%, Reynolds number 1,500,000, NCrit 9, 50-70m/s)&lt;/p&gt;&#xA;" OwnerUserId="14042" LastEditorUserId="19" LastEditDate="2016-10-14T13:46:43.597" LastActivityDate="2016-10-14T13:46:43.597" Title="What airfoil simulation software is suitable for a cut trailing edge?" Tags="&lt;airfoil&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26223" PostTypeId="1" AcceptedAnswerId="26335" CreationDate="2016-03-16T19:30:26.860" Score="17" ViewCount="1720" Body="&lt;p&gt;Let's say you have a &lt;a href=&quot;https://en.wikipedia.org/wiki/Gull&quot;&gt;seagull&lt;/a&gt; and a &lt;a href=&quot;http://www.aeryon.com/aeryon-scout&quot;&gt;drone&lt;/a&gt; of a comparable size.  Pretend either one was going to be ingested by large turbo fan engine, like the one found on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737#Engines&quot;&gt;737&lt;/a&gt; (eg., the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot;&gt;CFM-56&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which would cause more damage and why?  I'm particularly interested in how the fan blades and compressor stages will be affected by the difference in materials.  &lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="7532" LastEditDate="2016-03-16T19:53:21.873" LastActivityDate="2016-12-23T23:08:59.643" Title="Would a drone strike be more dangerous than a bird strike?" Tags="&lt;safety&gt;&lt;unmanned-aerial-vehicle&gt;&lt;turbofan&gt;" AnswerCount="3" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26224" PostTypeId="2" ParentId="26220" CreationDate="2016-03-16T19:35:54.343" Score="0" Body="&lt;p&gt;Please don't do something that you are not used to do at your first solo. First solo is always something you are waiting for, may be from the first day of your flying. So,I hope, it will not be that boring. It is not a good idea at all to depend upon a app when you are flying your 1st VFR solo. Please take enough preparation considering the terrain around your flying areas/routes. Search in Google map/earth to be very specific. Take enough preparation on the use of radio aids and diversion procedures. Be confident about emergencies. And, enjoy your solo. Good luck!!! Have a safe flight.&lt;/p&gt;&#xA;" OwnerUserId="13956" LastEditorUserId="100" LastEditDate="2016-03-17T14:08:39.103" LastActivityDate="2016-03-17T14:08:39.103" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26225" PostTypeId="2" ParentId="26220" CreationDate="2016-03-16T19:38:00.873" Score="14" Body="&lt;p&gt;No, there is no &quot;app&quot; you should be seeking at this stage of your training to do what you're asking about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, if you have questions about what you'll be doing while you're flying solo and how you'll be navigating, you should be discussing this with your instructor, not on an internet message board.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, whatever tools you'll use in flight need to be ones that you've used under supervision of an instructor, so that you understand how to use them, and what their limitations are.  Student solo flying is NOT the time to go exploring technology and apps you've not used before, in addition to the &lt;strong&gt;full-time&lt;/strong&gt; tasks of maintaining aircraft control, aviating, navigating, and communicating.  Too many dead pilots got focused on some technological toy and, without realizing it, lost situational awareness and/or control of their aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, before you are navigating anywhere solo, you need to be able to (and demonstrate to your instructor that you can) navigate successfully with the tools you have -- a map, compass, stopwatch, and the pre-flight planning you've done.  If you don't feel up to that task (which has been all of us early on in our training -- nobody is born with a built-in INS), work on those skills &lt;strong&gt;&lt;em&gt;with an instructor&lt;/em&gt;&lt;/strong&gt;.  Navigation apps are fine, but they supplement, rather than substitute for, your own skills when it comes to VFR navigation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fourth, the fact that you would come here to pose such a question, rather than to your instructor, is troublesome: you want an app that can enable you to go off on adventures sightseeing all of Barcelona, but you aren't discussing these plans with your instructor... perhaps he might not approve of all that you're planning?  Perhaps, maybe, you should limit your expectations of how much adventuring &amp;amp; exploring you'll undertake initially, and have a more complete discussion with your instructor of what you are, and are not, expected to do when, or if, you are signed off to solo.  (As stated in comments, the initial solo is typically pattern work only, rather than navigation.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying is about far more than aircraft control; it is a matter of judgement as well, and the difference between sound judgement and the lack of same can make the difference between a successful or a catastrophic outcome of a flight, at least as much as the difference between great and mediocre &quot;stick &amp;amp; rudder&quot; skills.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-16T19:38:00.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26226" PostTypeId="2" ParentId="26223" CreationDate="2016-03-16T19:52:44.030" Score="11" Body="&lt;p&gt;Birds are soft; drones tend to have at least some parts that are hard metal.  If a small bird goes through the fan blades of an engine, it gets pretty cleanly sliced, and often causes no damage at all.  (A bigger bird going into the core is a different matter -- ask Captain Sullenberger!)  I'd suspect that the metallic parts in a drone would cause far more damage to the fan blades than the bird would -- not necessarily anything immediately catastrophic, but nicks in the leading edge of the fan blades would probably be visible when looking at the shut-down engine, and those take maintenance action to resolve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Anything&lt;/em&gt; going into the core is more involved than if it went only into the fan blades, and the difference between bird flesh cooking and getting spit out versus the metal &amp;amp; plastic of the drone melting &amp;amp; causing clogs &amp;amp; damage is probably another point of difference -- the bird may cause damage, but the drone would probably be more likely to cause damage, and would probably cause greater damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To what extent the crew could tell the difference in flight, is hard to say.  (The experience with bird-strikes to the engines is pretty wide-spread, at least in terms of corporate knowledge; the number of drones-in-engines is far, far fewer.)  Knowing that something is wrong with a motor, and dealing with it, isn't the same as knowing the cause -- at least until you're back on the ground and the engine gets inspected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;UPDATE:&lt;/strong&gt; &lt;a href=&quot;http://www.popularmechanics.com/flight/drones/a24467/drone-plane-collision/?src=nl&amp;amp;mag=pop&amp;amp;list=nl_pnl_news&amp;amp;date=122316&quot; rel=&quot;nofollow noreferrer&quot;&gt;This &lt;em&gt;Popular Mechanics&lt;/em&gt; article&lt;/a&gt; discusses these sorts of issues, with some simulations linked, such as &lt;a href=&quot;https://vimeo.com/144401420&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-12-23T23:08:59.643" LastActivityDate="2016-12-23T23:08:59.643" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26227" PostTypeId="2" ParentId="26216" CreationDate="2016-03-16T19:52:52.410" Score="4" Body="&lt;p&gt;The are many types of runway. But the basic are paved, unpaved. Paved runway may be in form of rigid and flexible. Rigid is one which is made of concrete.Flexible runway are made of like bituminous. And the soft runway is one which is not paved. The runway may be on ice sand or water. But generally for a soft runway we can assume it as a grassy runway.    I did not find anything specific about the dirty runway. But in general we can think dirty means the runway conditions which are not so good for the engine when using of reverse thrust , applying brakes or maintaining direction while on take off roll. &lt;/p&gt;&#xA;" OwnerUserId="13956" LastEditorUserId="13956" LastEditDate="2016-03-16T22:33:02.243" LastActivityDate="2016-03-16T22:33:02.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26228" PostTypeId="1" AcceptedAnswerId="26247" CreationDate="2016-03-16T21:22:26.757" Score="6" ViewCount="1072" Body="&lt;p&gt;I'm studying for my PPL and I've accumulated roughly 70 hours towards my PPL and am only now doing my cross country training.  Sometimes life gets in the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a fan of my CFI but had a situation this past weekend that has made me a bit uncomfortable - he fell asleep on 3 occasions during my first cross-country.  Is this a sign of a bad CFI?  Is it something to be concerned about?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also wondering - is it important to know what you're going to be expected to work on before each lesson and we figure out what we're doing for the lesson during preflight?  Right now most of the agenda is being driven by me and I'm wondering if that's normal.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's a good/bad CFI?&lt;/p&gt;&#xA;" OwnerUserId="12060" LastActivityDate="2016-03-18T09:41:06.033" Title="Do I have a good CFI?" Tags="&lt;flight-training&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26229" PostTypeId="2" ParentId="26222" CreationDate="2016-03-16T21:32:00.887" Score="7" Body="&lt;p&gt;One tool you might want to consider is MIT's &lt;a href=&quot;http://web.mit.edu/drela/Public/web/xfoil/&quot;&gt;XFoil&lt;/a&gt;. I'm not sure I fully understand what you'd like to do, but this tool is used in many of MIT undergraduate aerodynamics classes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think it might work for your purposes, &lt;a href=&quot;http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-810-engineering-design-and-rapid-prototyping-january-iap-2005/index.htm&quot;&gt;here is a course&lt;/a&gt; by the program's creator from MIT's OpenCourseWare site. Lecture 3 is a tutorial on how to use XFoil. You might want to browse the OpenCourseWare site for more advanced uses of XFoil, too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck!&lt;/p&gt;&#xA;" OwnerUserId="13849" LastActivityDate="2016-03-16T21:32:00.887" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26230" PostTypeId="1" AcceptedAnswerId="26231" CreationDate="2016-03-16T21:37:05.133" Score="0" ViewCount="425" Body="&lt;p&gt;Air traffic controllers seem to broadcast this information, is anyone able to tell me what this is or what its use is for?&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;LTBA 162120Z 03008KT 360V080 9999 BKN035 06/02 Q1028 NOSIG&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Especially the last part, what does &lt;code&gt;NOSIG&lt;/code&gt; mean?&lt;/p&gt;&#xA;" OwnerUserId="14045" LastEditorUserId="1696" LastEditDate="2016-03-16T21:41:13.883" LastActivityDate="2016-03-16T21:41:13.883" Title="What is the meaning of this information provided by Air Traffic Control?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-03-16T22:32:13.310" ContentLicense="CC BY-SA 3.0" />
  <row Id="26231" PostTypeId="2" ParentId="26230" CreationDate="2016-03-16T21:40:04.693" Score="1" Body="&lt;p&gt;This is a METAR, a weather report. From the &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow&quot;&gt;Wikipedia article&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;METAR is a format for reporting weather information. A METAR weather&#xA;  report is predominantly used by pilots in fulfillment of a part of a&#xA;  pre-flight weather briefing, and by meteorologists, who use aggregated&#xA;  METAR information to assist in weather forecasting.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The meaning of this METAR is:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Location: LTBA&#xA;Day of month: 16&#xA;Time: 21:20 UTC&#xA;Wind:  True direction = 030 degrees, Speed: 8 knots&#xA;Wind direction is variable between 360 and 080&#xA;Visibility: 10 km or more&#xA;Clouds: Broken sky , at 3500 feet above aerodrome level&#xA;Temperature: 06 degrees Celsius&#xA;Dewpoint: 02 degrees Celsius&#xA;QNH (Sea-level pressure): 1028 hPa&#xA;No significant changes expected in the near future&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;code&gt;NOSIG&lt;/code&gt; means: No significant changes expected in the near future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See this METAR-TAF &lt;a href=&quot;http://heras-gilsanz.com/manuel/METAR-Decoder.html&quot; rel=&quot;nofollow&quot;&gt;decoder&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-03-16T21:40:04.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26232" PostTypeId="1" AcceptedAnswerId="26233" CreationDate="2016-03-16T23:48:34.253" Score="7" ViewCount="938" Body="&lt;p&gt;On this Garmin GMA 340:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the outer marker is blue and is designated O&lt;/li&gt;&#xA;&lt;li&gt;the middle mark is amber and is designated M&lt;/li&gt;&#xA;&lt;li&gt;the inner marker is white and is designated A and placed on the far left.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I looked at the GMA 340 Manual and could not find an answer although it does say Airway/Inner Marker.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would it say Airway if this is what the A indeed stands for and why even have an inner marker because that Garmin can't do a Category II approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/llsjO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/llsjO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="1696" LastEditDate="2016-03-17T20:30:15.060" LastActivityDate="2016-03-18T11:00:54.040" Title="Why does this Garmin GMA340 have an Airway/Inner marker indicator?" Tags="&lt;navigation&gt;&lt;ils&gt;&lt;ifr-navigation&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26233" PostTypeId="2" ParentId="26232" CreationDate="2016-03-17T00:33:08.913" Score="10" Body="&lt;p&gt;The &quot;A&quot; is not an inner marker. The A is an &lt;em&gt;airway marker.&lt;/em&gt; Airway markers were part of a now-obsolete system of &quot;red&quot; airways. They were placed along the enroute path and they could be picked up at cruise altitudes. The red airway system was mostly abandoned in the 60's and few &quot;A&quot; markers are still operational. Here's a map showing where they were located. They weren't at aerodromes. &#xA;&lt;img src=&quot;https://i.stack.imgur.com/jnT2Y.jpg&quot; alt=&quot;red airway beacons&quot;&gt;&#xA;&lt;a href=&quot;http://surveymarks.planetzhanna.com/map-of-ngs-airway-beacons/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airway markers transmit the same 3000 Hz audio frequency as inner markers so the airway marker can be used to pick up the inner marker. Since you say that unit is not certified for cat II it makes sense that they labeled it &quot;A&quot; instead of &quot;I&quot; although it can be used for inner markers. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-03-17T17:24:31.617" LastActivityDate="2016-03-17T17:24:31.617" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26234" PostTypeId="1" AcceptedAnswerId="26250" CreationDate="2016-03-17T02:17:12.940" Score="23" ViewCount="1752" Body="&lt;p&gt;On the Antonov-225's split vertical stabilizers, there is a 'spiked' structure pointing directly rearwards (as you can see below). What is the purpose of these two structures?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6UhL6.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6UhL6.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.airplane-pictures.net/photo/471471/ur-82060-antonov-airlines-design-bureau-antonov-an-225-mriya/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="14050" LastEditorUserId="62" LastEditDate="2016-03-17T18:02:49.657" LastActivityDate="2016-03-17T18:02:49.657" Title="What are the spiky things on the back of the Antonov-225 vertical stabilizers?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;vertical-stabilizer&gt;&lt;antonov-225&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26236" PostTypeId="1" CreationDate="2016-03-17T03:31:11.973" Score="7" ViewCount="66" Body="&lt;p&gt;Reviewing the ILS 7 approach at Barrow (&lt;a href=&quot;http://www.airnav.com/depart?http://155.178.201.160/d-tpp/1603/05463ILD7.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;PABR&lt;/a&gt;) revealed something I have never seen before:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VlxCe.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VlxCe.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, I saw the note (and diagram) in the upper left corner, so I was able to infer that this is a &quot;&lt;strong&gt;grid course&lt;/strong&gt;&quot; but I still have no idea what this is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there anyone on Aviation SE that knows and can explain?&lt;/p&gt;&#xA;" OwnerUserId="1968" LastEditorUserId="595" LastEditDate="2016-03-17T04:50:15.367" LastActivityDate="2016-03-17T04:50:15.367" Title="What is a grid course?" Tags="&lt;instrument-flight-rules&gt;&lt;navigation&gt;&lt;polar&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2016-03-17T11:45:06.250" ContentLicense="CC BY-SA 3.0" />
  <row Id="26237" PostTypeId="2" ParentId="21222" CreationDate="2016-03-17T03:35:23.747" Score="1" Body="&lt;p&gt;Biggest simplification and weight saving would be to totally eliminate the whole mechanical collective &amp;amp; pitch mechanisms and use electrically activated controls to move self energising control flaps on the trailing edge of the blades to drive the required blade pitch alterations in the manner of the Kaman K-Max intermesher - a very successful helio with many years of proven service.&lt;/p&gt;&#xA;" OwnerUserId="14052" LastActivityDate="2016-03-17T03:35:23.747" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26238" PostTypeId="2" ParentId="26232" CreationDate="2016-03-17T04:04:46.533" Score="1" Body="&lt;p&gt;You have mentioned that outer marker is designated as B which is not. It is 'O'. Now the question is if O is outer marker and M is middle marker then what is indicated by A? A serves two purpose, Inner/ Airway marker. So A does not indicate only Airway marker.&#xA;The airway marker was used to indicate reporting points along the center line of now obsolete &quot;Red&quot; airways which  &lt;strong&gt;Tom McW&lt;/strong&gt; mentioned.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was sometimes a &quot;fan&quot; marker, whose radiated pattern was elongated at right angles across the airway course so an aircraft slightly off course would still receive it. Please do not confuse about fan marker, The term fan marker refers to the older type of beacons used mostly for en-route navigation. Most of these are obsolete now a days. There are uses of marker beacon on the instrument approaches mainly.&lt;/p&gt;&#xA;" OwnerUserId="13956" LastEditorUserId="5517" LastEditDate="2016-03-18T11:00:54.040" LastActivityDate="2016-03-18T11:00:54.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26239" PostTypeId="1" AcceptedAnswerId="26241" CreationDate="2016-03-17T08:32:55.897" Score="5" ViewCount="451" Body="&lt;p&gt;I was just reading this &lt;a href=&quot;http://news.sky.com/story/1661072/plane-six-times-faster-than-sound-is-on-horizon&quot; rel=&quot;nofollow&quot;&gt;story&lt;/a&gt; from Sky news and reported the following &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Lockheed Martin says it is close to developing a military plane that flies at Mach 6 - six times the speed of sound, which travels at around 762mph (1,236km per hour).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Am I missing something, or is that a misprint? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;6 * speed of sound at sea level = 4567.2423 miles per hour&lt;/strong&gt; &lt;/p&gt;&#xA;" OwnerUserId="1732" LastEditorDisplayName="user5664" LastEditDate="2016-10-03T15:33:55.883" LastActivityDate="2016-10-03T15:33:55.883" Title="SR-72 --- is the speed reported in this story wrong?" Tags="&lt;military&gt;&lt;airspeed&gt;&lt;sr-72&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26240" PostTypeId="2" ParentId="26239" CreationDate="2016-03-17T08:43:58.970" Score="4" Body="&lt;p&gt;While I'd in general remain sceptical of anything that Sky News talks about the numbers do seem realistic. Aviation Week (amongst others) have mentioned similar speeds and they're not beyond the realm of likelihood. Hypersonic test vehicles have already reached above Mach 5 and many of the designs are capable of the speeds talked about in the article. It's also worth noting that the SR-72 wouldn't enter service for another 15 years.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's impossible to say for definite, though, as we're discussing something that is: a) In the design stage and b) Very secretive.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-03-17T08:43:58.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26241" PostTypeId="2" ParentId="26239" CreationDate="2016-03-17T10:55:11.100" Score="9" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;is the speed reported in this story wrong?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;h1&gt;No&lt;/h1&gt;&#xA;&lt;p&gt;No it is not a misprint that the SR-72 is intended to be capable of Mach 6&lt;/p&gt;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://www.lockheedmartin.co.uk/us/news/features/2015/sr-72.html&quot; rel=&quot;noreferrer&quot;&gt;horses' mouth&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Envisioned as an unmanned aircraft, the SR-72 would fly at speeds up to &lt;strong&gt;Mach 6&lt;/strong&gt;, or six times the speed of sound. At this speed, the aircraft would be so fast, an adversary would have no time to react or hide.&lt;/p&gt;&#xA;&lt;p&gt;The SR-72’s design incorporates lessons learned from the HTV-2, which flew to a top speed of &lt;strong&gt;Mach 20&lt;/strong&gt;, or 13,000 mph, with a surface temperature of 3500°F.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h1&gt;Yes&lt;/h1&gt;&#xA;&lt;p&gt;Yes it is not true that Mach 6 is necessarily 4567.2423 MPH&lt;/p&gt;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Speed_of_sound#/media/File:Comparison_US_standard_atmosphere_1962.svg&quot; rel=&quot;noreferrer&quot;&gt;elsewhere&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hLug8.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hLug8.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;&lt;em&gt;Cmglee. License:CC by SA 3&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-17T11:24:19.657" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26242" PostTypeId="1" CreationDate="2016-03-17T11:31:39.307" Score="6" ViewCount="221" Body="&lt;p&gt;I'm currently learning about Rotary Winged Aircraft, and I have a question regarding lift and fluid flow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given two wings of different material but same shape, will there be a difference in the amount of lift, and the amount of air that is pushed down? Is the lift created related to the material choice in any way? &lt;/p&gt;&#xA;" OwnerUserId="14058" LastEditorUserId="62" LastEditDate="2016-03-17T13:20:07.943" LastActivityDate="2016-03-17T21:04:20.133" Title="Is there a relation between material choice and produced lift at rotation?" Tags="&lt;aerodynamics&gt;&lt;aircraft-performance&gt;&lt;helicopter&gt;&lt;lift&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26245" PostTypeId="2" ParentId="21222" CreationDate="2016-03-17T13:41:23.527" Score="1" Body="&lt;p&gt;Helicopters certified for IFR must meet the requirements of &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/part-27/appendix-B&quot; rel=&quot;nofollow&quot;&gt;14 CFR Part 27 Appendix B&lt;/a&gt;, which specifies certain static and dynamic stability that can only be achieved through the use of electrical systems to control the rotor system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of different kinds of systems which are used to achieve this certification, and all of them use either electric or electro-hydraulic actuators to achieve stability.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-03-17T13:41:23.527" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26247" PostTypeId="2" ParentId="26228" CreationDate="2016-03-17T13:52:39.477" Score="6" Body="&lt;p&gt;Before I comment I have to ask your training habit: Do you fly one lesson each week, or only occasional lessons because you're so busy, or 3 flying days each week, or full time?&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sometimes life gets in the way&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In terms of progress, 70 hours and just starting cross country flights seems to be on the slow side. But then, if you're not training regularly, you can't blame the CFI for spending some time reviewing previous materials during each lesson.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally, the flight lesson pre-flight should go like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CFI: Today we will be practicing steep turns. We will takeoff, head North to this area on the chart and practice there. Then we will fly North East and proceed to this airfield to practice some touch and go. Our weather report says there is weather system South of us, we need to keep an eye on it in case it moves North. I will work on the radios and navigate, you will be doing all the flying. Questions?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This establishes clear goals of the lesson. A good lesson should also conclude with a post-flight debriefing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;CFI: Today I noticed that you did not enter the traffic pattern correctly. You entered like this, which is not good because of that, that, and that. Given the situation, you should have went like this. We will be practicing more traffic patterns in our next lesson.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the agenda is driven by the instructor instead, you'll get more benefits:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The goals of the lessons are clear.&lt;/li&gt;&#xA;&lt;li&gt;The instructor can adjust lessons based on your weakness. For example, if you were rather sluggish during engine-out emergencies, the CFI should review emergency procedures with you on the ground and give you more practice in the air.&lt;/li&gt;&#xA;&lt;li&gt;You may not be aware that you are not getting enough practice in some areas.&lt;/li&gt;&#xA;&lt;li&gt;You can prepare for the next lesson ahead. For example, if your next lesson is a cross country, you can review flight planning, navigation principles &amp;amp; airspace regulations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is your situation normal? I'm not an instructor so I don't know, but it can be better. Then again, if your flying schedule is rather random, learning efficiency would be lower, and you end up spending more flying time and money.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Now, falling asleep......To me, this is a big No No. I am just a student. I have not been certified (yet) that I can operate an airplane safely:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What if I make a navigation error and end up heading to Area 51?&lt;/li&gt;&#xA;&lt;li&gt;What if I'm heading into IMC and need to turn around?&lt;/li&gt;&#xA;&lt;li&gt;What if the fuel level is reducing at a dangerous rate but I didn't notice?&lt;/li&gt;&#xA;&lt;li&gt;What if I got a stuck elevator?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A flight instructor is seated in the same cockpit with the student to correct mistakes or react to situations in a timely manner. To fall asleep during a flight lesson is an irresponsible behavior to the student and other people on the ground who might get hurt if your plane crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, flight instructors are all humans and we all tend to make mistakes. Perhaps he was overstretching himself. Perhaps he got a family emergency the night before and stayed up really late. If it was just one flight, I would pass but keep an eye on. If it happens continuously, it might be a good time to turn away and look somewhere else while you're still safe.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-03-17T13:52:39.477" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26248" PostTypeId="2" ParentId="25851" CreationDate="2016-03-17T14:05:24.173" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;If I attempt to continue maintaining the flare, attempting to come to a stop, I will sink and if I don't do anything about it, I will hit the ground. Why?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;if you continue to maintain aft cyclic after the flare, you will hit the ground because some of the lift which is being generated will be used to fly the helicopter backwards, and you won't have enough power in to both maintain altitude and also maintain backwards flight (which is what you are commanding with aft cyclic). This is why we level off after the flare: to use all the lift in the vertical direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its the exact opposite of take-off: if you are in a hover on the runway, and push the nose over to the 60KIAS nose-down attitude, you will descend into the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although I have never tried it, I imagine that at the peak of the flare, if I add (a lot?) of power without changing the attitude (much:), I will not descend into the runway, but rather I will start to fly backwards. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-17T14:56:46.630" LastActivityDate="2016-03-17T14:56:46.630" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26249" PostTypeId="2" ParentId="26217" CreationDate="2016-03-17T14:47:45.613" Score="3" Body="&lt;p&gt;I made &lt;a href=&quot;https://aviation.stackexchange.com/questions/26217/what-are-the-pros-cons-of-ram-air-turbines#comment63520_26219&quot;&gt;a comment&lt;/a&gt; on TomMcW's &lt;a href=&quot;https://aviation.stackexchange.com/a/26219/5517&quot;&gt;answer&lt;/a&gt;, but I think it deserves to be an answer:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the answer lies in your question: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_EA-6B_Prowler&quot; rel=&quot;nofollow noreferrer&quot;&gt;EA-6B&lt;/a&gt;, which the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_EA-18G_Growler&quot; rel=&quot;nofollow noreferrer&quot;&gt;Growler&lt;/a&gt; replaced, was also a &lt;strong&gt;modified attack aircraft&lt;/strong&gt; using jamming pods with ram air turbines. &lt;sub&gt;Emphasis and links mine&lt;/sub&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If they were designing an electronic warfare aircraft from scratch, I'm sure that all the electronics would be powered by generators driven by the main engine(s). These engines would be sized to provide appropriate thrust for the expected mission profile &lt;em&gt;and&lt;/em&gt; have excess capacity to provide power for the electronics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, since they are modifying existing aircraft for a new role they've found there is not enough excess capacity in the existing engines for the expected flight regimes &lt;em&gt;and&lt;/em&gt; electricity generation, so dealing with the extra drag from the RAT is a cheaper and more expedient alternative than re-engining the the &lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F/A-18_Hornet&quot; rel=&quot;nofollow noreferrer&quot;&gt;FA-18&lt;/a&gt; (or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Grumman_A-6_Intruder&quot; rel=&quot;nofollow noreferrer&quot;&gt;A-6&lt;/a&gt; before it). Also, the cables needed to bring the power from the generator to the wing station must be added, and in tightly packed combat aircraft the space might not be there to add the wiring later. The RAT-driven pod only needs to be hooked up to a communication bus and brings its own power, so it can be designed once and used in a variety of aircraft. Multi-function displays in the cockpit just need a software upgrade, and the aircraft can perform reasonably well in its new role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;hr&gt;Addressing the recently added text about larger aircraft not needing the RAT:&lt;br&gt;&#xA;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_E-3_Sentry&quot; rel=&quot;nofollow noreferrer&quot;&gt;E-3 Sentry&lt;/a&gt; (for example) is powered by the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56-2&lt;/a&gt; producing 18,000-34,000 pounds of thrust while the 707 it was based on was powered by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT3D&quot; rel=&quot;nofollow noreferrer&quot;&gt;P&amp;amp;W JT3D-3B&lt;/a&gt; produced only 18,000 pounds of thrust. Per &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56#CFM56-2_series&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;, the E-3 used CFM56-2A-2 version producing 24,000 pounds of thrust, thus it had the power for its normal flight regime plus power to spare for all the extra electrical demands of its electronic warfare role.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-17T21:40:35.790" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26250" PostTypeId="2" ParentId="26234" CreationDate="2016-03-17T15:36:27.097" Score="20" Body="&lt;p&gt;It appears to be the extension of the aerodynamic fairing between the vertical and horizontal tails (note that the horizontal tail extends outside the vertical one). It can be seen more clearly in the following image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iXScx.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iXScx.jpg&quot; alt=&quot;An 225&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Image from &lt;a href=&quot;http://www.diecastaircraftforum.com/1-1-scale-commercial-aviation/89208-whats-more-impressive-than-a380-tupolev-youll-love-one.html&quot; rel=&quot;noreferrer&quot;&gt;diecastaircraftforum.com&lt;/a&gt;. Original image appears to be from airliners.net&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type of fairings (usually called &lt;a href=&quot;http://www.google.co.in/patents/US3417946&quot; rel=&quot;noreferrer&quot;&gt;bullet fairings&lt;/a&gt;) are found in 'T' tails and other types of tails (like cruciform tail) where two surface intersect each other at right angles and are used to reduce interference drag (and flow seperation). For example, the following image shows the fairing in &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-141_Starlifter&quot; rel=&quot;noreferrer&quot;&gt;C-141 Starlifter&lt;/a&gt;, an aircraft with 'T' tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eNfv2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eNfv2.jpg&quot; alt=&quot;C141&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.airplanesofthepast.com/c141-starlifter.htm&quot; rel=&quot;noreferrer&quot;&gt;airplanesofthepast.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2171" LastEditDate="2016-03-17T17:24:59.163" LastActivityDate="2016-03-17T17:24:59.163" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26252" PostTypeId="1" CreationDate="2016-03-17T20:19:22.297" Score="7" ViewCount="344" Body="&lt;p&gt;Does anybody have experience with getting complex modules that were designed by others for common use, approved for incorporation in an airborne system that is at DAL A, B, or C and thus requires FAA approval?  I am doing research on the topic of how optimal the current approval guidelines are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question is of interest for LRU's (Line Replaceable Units), CBA's (Ciruit Board Assemblies, SoC (System on a Chip sunits) and other integrated technology modules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If anybody out there has interacted with a DER and either found the means of demonstrating compliance to be sensible and practical, or can point out either gaps where potential errors could have snuck through or places where the approval process is impractical, I would appreciate it a lot.&lt;/p&gt;&#xA;" OwnerUserId="12120" LastEditorUserId="19" LastEditDate="2016-06-28T16:18:29.313" LastActivityDate="2016-11-11T14:50:34.403" Title="How can one demonstrate/assure safety for LRU's, CBAs, SoC's and other integrated modules?" Tags="&lt;safety&gt;&lt;easa-regulations&gt;&lt;aircraft-certification&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26253" PostTypeId="2" ParentId="136" CreationDate="2016-03-17T20:47:38.223" Score="0" Body="&lt;p&gt;For the most part, the EASA guidelines (as issued, for example, in Certification Memoranda, and the FAA guidelines (as issued in Advisory Circulars and in guidance to those acting for the certification authority, such as 8110.105) are pretty much harmonized.  (and that goes for the JAA as well.)  There are some minor spots whre EASA is either ahead of or behind the FAA guidelines; For example, there is a paragraph of EASA CM SWE?? - 001 [don't remember the exact number] (dated 2014) that deals with a small class of LRU issues and that is not yet in any FAA guidelines that I could find.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even though the fundanentals are closely aligned, you still have to demonstrate compliance to the FAA authority after having been certified under EASA, and vice-versa.  However, since the process of obtaining certification pretty much demands attention to keeping your paperwork in order, your testing comprehensive and well-organized, and your certification artifacts available, once you have passed in one context the remaining work to be certified in the other is at least 90-95% in place.&lt;/p&gt;&#xA;" OwnerUserId="12120" LastActivityDate="2016-03-17T20:47:38.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26254" PostTypeId="2" ParentId="26242" CreationDate="2016-03-17T21:04:20.133" Score="6" Body="&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some materials are easier to shape (think composites versus metal) or stay in shape better over time or under stress (think metal versus wood). This difference between the intended and the actual shape will have the biggest material-related impact on lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you slightly change the question and ask for useful lift (lift minus weight of the structure), the stiffness and relative strength of the specific material must be added to the comparison. Useful parameters are the ultimate strength relative to density (&lt;a href=&quot;https://en.wikipedia.org/wiki/Specific_strength&quot;&gt;breaking length&lt;/a&gt;) or stiffness relative to density (strain length). A stiff structure deforms less under load, so its shape will change less. Ideally, the structure is shaped such that only under load it assumes the aerodynamically most advantageous shape while its elasticity helps it to avoid being overloaded (&lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroelasticity&quot;&gt;aeroelastic&lt;/a&gt; tailoring).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The surface finish is also material-related, but is more affected by the manufacturing method. A rough surface is better at very low flow speeds while a smooth surface is better at moderate to high flow speeds.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-17T21:04:20.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26255" PostTypeId="2" ParentId="26169" CreationDate="2016-03-18T00:37:13.223" Score="0" Body="&lt;p&gt;Water and with little soap mixed in.  Don't get crazy with cleaning solutions.  I think I used just a little bit of Dawn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;DO NOT WASH YOUR PLANE TOO OFTEN AND AVOID PRESSURE WASHING!!  Too-frequent washing will cause water will to work its way into the wheel bearings and accelerate corrosion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I washed mine a few times a year but dusted it frequently.  The only routine cleaning I did was bug removal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also gave the belly a once-over with Goop hand cleaner (no pumice, of course) and that worked magic on the exhaust, oil, grease, and hydraulic fluid stains.  I had to make a few passes but it was worth the effort.  The paint looked new!  Spot cleaning was simple after that.  Goop should be a staple on every hangar!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Use soap and water or plexiglass cleaner on windows and lense covers.  Never use windex or other harsh cleaners.  I used plexus to clean bugs from the wings as well.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-03-18T04:10:55.010" LastActivityDate="2016-03-18T04:10:55.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26257" PostTypeId="2" ParentId="8913" CreationDate="2016-03-18T07:46:03.320" Score="2" Body="&lt;p&gt;For a truly one-shot deal, you don't even need &quot;enough&quot; runway, as long as you put enough EMAS at the end to handle the size, weight, and speed you expect to be dealing with. Sure, the EMAS itself gets destroyed in the process, but even an old 747 is probably a lot more expensive, and it is pretty well done flying at the end of this adventure, right?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-18T07:46:03.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26258" PostTypeId="2" ParentId="26228" CreationDate="2016-03-18T09:05:45.410" Score="11" Body="&lt;p&gt;I'm a CFI/MEI.  I have 700-800 hours teaching private pilot students in the part 61 environment.  That's not an awesome amount but I think it's enough to comment on this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This guy is wildly unprofessional, maybe even criminally negligent.  You are paying him to observe you, to provide feedback, and to keep you safe.  He can do none of those things while he is sleeping on the job.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You have a lazy instructor and I'm curious to know in what other ways he is failing to teach you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's his job to excercise good judgement and scrub a flight if he's not up for it.  If he's overworked he shouldn't be flying.  That's his problem, not yours.  He has no excuse for his behavior and he's setting a terrible example for you to follow.  DO NOT be like your instructor.  I hope you're not using him as a role model for what a good pilot should be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He's failing to demonstrate sound judgement and showing you that complacency is OK.&#xA;He's not challenging you or looking for teachable moments.&#xA;He's exhibiting classic hazardous attitudes...invulnerability and anti-authourity at a minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd talk to him first and then fire him if this nonsense continues.  I'd also demand a refund on CFI billing for his nap time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And, yes, there should be a defined lesson plan with expectations for each lesson.  This goes for pt61 and pt141 schools.  Every CFI should have created plans during their CFI training.  I have no idea how a CFI applicant can pass a CFI practical or oral exam without a comprehensive collection of lesson plans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, it's not OK for you to be in charge of what is covered.  You should know what the next lesson will cover so you can prepare.  He needs to give you the training plan and he needs to drive it.  Again, it's his job, it's why you pay him.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think this guy is milking you for billable hours.  You might just be a cash pinata for him.  Either that or he's just incompetent.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-03-18T09:41:06.033" LastActivityDate="2016-03-18T09:41:06.033" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26259" PostTypeId="2" ParentId="26220" CreationDate="2016-03-18T09:10:27.753" Score="0" Body="&lt;p&gt;In a solo, you shouldn't be doing anything you haven't already done with an instructor onboard, but without his assistance. If you haven't navigated the trip you plan to fly solo yet without your instructor doing the navigation for you, then you aren't ready to solo. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-03-18T09:10:27.753" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26260" PostTypeId="2" ParentId="25322" CreationDate="2016-03-18T12:56:59.593" Score="3" Body="&lt;p&gt;I don't know much about LSAs, but the regulations say that LSAs with a special airworthiness certificate may not be used in commercial operations (with two exceptions).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/aircraft/gen_av/light_sport/media/LSA_Cert_8July2013.pdf&quot; rel=&quot;nofollow&quot;&gt;This FAA document&lt;/a&gt; says that a weight-shift-control LSA will have a special airworthiness certificate:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A special airworthiness certificate in the light-sport category is&#xA;  issued to an aircraft that meets the definition of light-sport&#xA;  aircraft (LSA), is manufactured to the applicable consensus standards,&#xA;  and is one of the following five classes of the LSA category:&#xA;  airplanes, gliders, powered parachutes, weight-shift-control aircraft&#xA;  (commonly called trikes), and lighter-than-air aircraft (balloons and&#xA;  airships).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1327&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.327&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may operate an aircraft that has a special airworthiness&#xA;  certificate in the light-sport category for compensation or hire&#xA;  except—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) To tow a glider or an unpowered ultralight vehicle in accordance&#xA;  with §91.309 of this chapter; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) To conduct flight training.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-18T12:56:59.593" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26261" PostTypeId="1" AcceptedAnswerId="26263" CreationDate="2016-03-18T14:22:08.523" Score="27" ViewCount="6739" Body="&lt;p&gt;There is an account in a TSB Canada &lt;a href=&quot;http://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/1998/a98q0029/a98q0029.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;investigation report&lt;/a&gt; after a loss of radio and transponder:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The emergency procedure to be followed by a pilot to alert radar&#xA;stations when in distress and unable to establish radio contact is to&#xA;fly a left-hand triangular pattern twice with two-minute legs, resume&#xA;course and repeat the procedure at 20-minute intervals.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PIrJe.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PIrJe.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;After the loss of radio, the transponder was switched to 7600 (signal not picked up by ATC). Shortly thereafter, the aircraft experienced a complete loss of electrical power. The pilot did the triangular maneuver.&lt;/p&gt;&#xA;&lt;p&gt;This story took place in 1998: Is this signal still used today? and has the same meaning in all ICAO countries?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-09-18T12:01:33.547" LastActivityDate="2020-09-18T12:01:33.547" Title="Does air traffic control identify a distress situation when an aircraft flies triangles in the sky?" Tags="&lt;emergency&gt;&lt;radio-communications&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26262" PostTypeId="2" ParentId="26261" CreationDate="2016-03-18T14:38:53.997" Score="9" Body="&lt;p&gt;&lt;strike&gt;There is no standard pattern for an emergency&lt;/strike&gt;(see Pondlife's answer), I suppose if you were really bored you could spell out &quot;HELP&quot; on somebodies radar scope, but if you are operating VFR in the US a controller really isn't going to notice that you are flying a triangular pattern. This would be dangerous though around airfields, since you want to remain in the standard pattern so you aren't confusing or surprising other pilots by coming in from odd angles. The best thing to do in this situation is to fly normally in a manner which other pilots can anticipate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Squawking 7600 is the code for &quot;Communications Failure&quot; and this is the procedure I was taught for VFR (in the US), although it should hold for any ICAO airspace/field:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Set Transponder to 7600&lt;/li&gt;&#xA;&lt;li&gt;Say intentions over the radio, the transmit may still work but the receive may be dead&lt;/li&gt;&#xA;&lt;li&gt;Enter the traffic pattern with a standard pattern entry&lt;/li&gt;&#xA;&lt;li&gt;Watch the tower for &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_light_signals&quot; rel=&quot;noreferrer&quot;&gt;light-gun signals&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Acknowledge Signals by rocking wings or flashing landing/taxi lights.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For an un-towered field, you enter the pattern as normal and follow the traffic flow in to land, taking care to watch for other aircraft on a straight-in or other odd approach. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Class-B offers other issues, if you are outside of class-B and lose your radio you cannot enter the class-B airspace even squawking 7600. If you are already in class-B then you may be able to continue but personally if the aircraft is otherwise flyable I'd head for the nearest class-D or C. There may be some exceptions to this for IFR flight plans, but that should be spelled out in the information in the link below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a good read of the &lt;a href=&quot;http://code7700.com/lost_communications.html&quot; rel=&quot;noreferrer&quot;&gt;Radio Loss Procedures&lt;/a&gt; and exceptions to the ICAO standard procedures for different operational areas below it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, you should be flying with a current AFD, and using your cell-phone to contact the tower is a perfectly acceptable way of establishing communications.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-18T15:13:41.003" LastActivityDate="2016-03-18T15:13:41.003" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26263" PostTypeId="2" ParentId="26261" CreationDate="2016-03-18T15:10:28.980" Score="38" Body="&lt;p&gt;To my surprise, this does exist, at least in the UK. According to the &lt;a href=&quot;https://publicapps.caa.co.uk/docs/33/CAP493%20Edition%206%20Amendment%201%20Corrigendum%20(April%202015).pdf&quot; rel=&quot;noreferrer&quot;&gt;Manual of Air Traffic Services&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;h2&gt;7 Emergency Triangle Procedure&lt;/h2&gt;&#xA;  &#xA;  &lt;p&gt;7.1 Pilots lost or uncertain of position and experiencing either transmitter or complete radio failure are advised, as a last resort, to carry out special procedures to indicate to controllers that they&#xA;  require assistance.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;7.2 The aircraft fly at least two triangular patterns, before resuming course, as follows: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Table 1&lt;/strong&gt;:&#xA;  &lt;a href=&quot;https://i.stack.imgur.com/bJX4d.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bJX4d.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;7.3 If a triangular pattern is observed, controllers shall advise the D&amp;amp;D cell of the position and track and continue to plot the aircraft&#xA;  whilst it is within ATS surveillance system cover. Controllers should&#xA;  also be aware of the effect wind may have on the pilot’s ability to&#xA;  fly an accurate triangle.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I say &quot;to my surprise&quot; because there are well-established procedures for &lt;a href=&quot;https://aviation.stackexchange.com/q/25316/62&quot;&gt;comms failure under IFR&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/q/3794/62&quot;&gt;under VFR&lt;/a&gt;. But having said that, it's possible that the triangle procedure is more useful in the UK (for example) than the US, where there are usually plenty of uncontrolled airports around and many pilots have no need to talk to ATC anyway. In the UK, with a much smaller airspace, fewer airports and more ATC control (at least, that's my understanding), it may be more critical to give even VFR aircraft a &quot;last resort&quot; to contact ATC.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-03-19T19:26:42.373" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26265" PostTypeId="1" CreationDate="2016-03-18T16:12:38.440" Score="6" ViewCount="4626" Body="&lt;p&gt;Raymer in his book suggests a method to find wing loading W/S (for example we consider jet with 2 engines) (starting from specific thrust $\frac TW$, $CL_{to}$, density/reference density etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In step 1:  he suggests to use graphics &quot;Fig. 5.4 Takeoff distance estimation&quot;: you enter takeoff distance (in ordinate), so .. in abscissa you can determine Takeoff Parameter (&quot;TOP&quot;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Step 2: From &quot;TOP&quot; you can find $\frac WS=TOP\cdot \sigma \cdot CL_{to} \cdot \frac tW$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The questions are: in figure 5.4 you can find many diagrams: takeoff distance for:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) &quot;Balanced field Length&quot;&lt;br&gt;&#xA;b) &quot;over 50 ft&quot;&lt;br&gt;&#xA;c) &quot;ground roll&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which one I have to use?&#xA;What is the difference among them?&#xA;Which curve you have to use, in order to calculate &quot;take off parameter&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Daniel P. Raymer, Aircraft design: a conceptual approach. Chapter 5 Thrust-to-weight ratio and wing loading, paragraph 5.3 Wing Loading, sub-paragraph Takeoff Distance, page 88-89 and &quot;Fig. 5.4 Takeoff distance estimation&quot;.&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="1696" LastEditDate="2016-03-18T16:22:32.873" LastActivityDate="2017-05-10T13:41:03.837" Title="In Raymer diagram &quot;Take off parameter- Take off distance&quot;, what is the difference among &quot;balanced field length&quot;, &quot;over 50 ft&quot;, &quot;ground roll&quot;?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26267" PostTypeId="1" CreationDate="2016-03-18T17:18:01.763" Score="1" ViewCount="1496" Body="&lt;p&gt;My understanding of trim (on non fly by wire aircrafts) is that when the pilot feels force on his column or side stick, he trims the aircraft (either up/down) until the forces on the stick or yoke are neutralized. But in fly by wire systems, the pilot does not feel any force on the stick or yoke. In such case how does pilot know when to trim the aircraft (be it pitch/roll/rudder trim).&#xA;Or does flight control computer computes the trim required automatically? In such case, what happens during the direct mode (or alternate law) when flight control computers are no longer in control and pilot commands directly go to actuator controller electronics.&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2016-03-20T22:14:41.213" Title="How does pilot know when to trim when flying an aircraft that have fly by wire flight control computer" Tags="&lt;fly-by-wire&gt;&lt;trim&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-03-18T19:50:38.603" ContentLicense="CC BY-SA 3.0" />
  <row Id="26268" PostTypeId="2" ParentId="26267" CreationDate="2016-03-18T18:12:41.330" Score="6" Body="&lt;p&gt;Fly-by-wire just means that the control column is not connected to the control surfaces (hydro-)mechanically, but using digital (electrical or optical) signal wires. That says nothing about how the controls behave. There are two basic ways they can:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The Boeing way:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Force and position is transmitted in both directions, emulating&#xA;control with mechanical link. The pilot feels force on the control surfaces and trims as usual.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Airbus way:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The position of the control column corresponds to wing loading in pitch and roll rate in roll axis. The computer manipulates the controls to achieve the target values. The control column is spring-loaded, so force always corresponds to position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trim is operated by the computer to balance the control surface for wing loading of 1 G (or is not a separate control at all as in case of FBW fighters with all moving stabilator).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when the system is in direct law (during take-off or if degraded due to fault), the trim still works more or less normally. The centred position of control stick corresponds to the trimmed position of the control surface, so if the pilot feels force on the control stick, because it is displaced, they dial trim and reduce pressure on the stick until the plane flies straight with the stick centred.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The Airbus way is used on Airbus A320 and all newer models, Sukhoi Su100 and some fighters (since F16).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Boeing way is used on Boeing 777, 787 and, IIRC, some regional jets.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-20T22:14:41.213" LastActivityDate="2016-03-20T22:14:41.213" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26269" PostTypeId="2" ParentId="26265" CreationDate="2016-03-18T20:16:17.443" Score="7" Body="&lt;p&gt;Let's clarify:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large commercial airplanes take off in a way which ensures there is sufficient runway length to stop in case of aborted takeoff. There is a speed threshold, &lt;em&gt;V1 speed&lt;/em&gt; or &lt;em&gt;decision speed&lt;/em&gt;, that determines whether the takeoff can still be aborted, or the airplane must continue and liftoff whatever happens. See &lt;a href=&quot;https://en.wikipedia.org/wiki/Balanced_field_takeoff&quot; rel=&quot;nofollow noreferrer&quot;&gt;balanced field takeoff&lt;/a&gt; on Wikipedia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;em&gt;balanced field length&lt;/em&gt; is the minimum runway length to execute a balanced field takeoff for a given aircraft. The V1 speed in this case is the lowest possible. Additional runway length allows greater V1 to be selected (greater V1 means a greater portion of the ground roll with a possibility to abort the takeoff).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/enBZy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/enBZy.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;V1 value and balanced field length (&lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=RANGE_OF_V1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;50 ft distance&lt;/em&gt;: This is the distance from the start of the ground roll to the point where the aircraft is airborne and 50 ft over the runway, to ensure obstacle clearance. &lt;em&gt;35 ft&lt;/em&gt; is another typical obstacle clearance in the US, and indeed the distance to climb to 35 ft is shorter than the previous one (a 35 ft clearance is implicitly used to compute the balanced field distance)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4V0G4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4V0G4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Takeoff roll distance and Obstacle clearance distance (&lt;a href=&quot;http://www.srl.gatech.edu/education/ME6105/Projects/Fa09/UAV/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Using the diagram&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://stl-www.aero.kyushu-u.ac.jp/member/tani/tokuron/2014Lecture/CD201404_DesignProcess_configuration.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this slideshow&lt;/a&gt; which reproduces the figure you refer to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nCWhJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nCWhJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://stl-www.aero.kyushu-u.ac.jp/member/tani/tokuron/2014Lecture/CD201404_DesignProcess_configuration.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This depicts the relationship between takeoff parameter and different distances, either the ground roll distance or the obstacle clearance distance (35 and 50 ft) in the three types of takeoff described above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three groups from left to right:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Jet using balanced field T/O (the obstacle clearance is implicitly 35 ft).&lt;/li&gt;&#xA;&lt;li&gt;Jet not using balanced field T/O.&lt;/li&gt;&#xA;&lt;li&gt;Propeller (not using balanced field T/O).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In these groups, there are one or two data provided:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Jet using &lt;em&gt;balanced field T/O&lt;/em&gt;. The only distance provided is the balanced field length (distance to accelerate, abort the T/O at V1 and decelerate). You must choose the right curve, depending on the number of engines (&lt;em&gt;twin&lt;/em&gt;, &lt;em&gt;tri&lt;/em&gt; or &lt;em&gt;four-engine&lt;/em&gt;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Jet&lt;/em&gt; / &lt;em&gt;propeller&lt;/em&gt;. There are two distance provided and you may need both. &lt;em&gt;Ground roll&lt;/em&gt; is the distance until the aircraft leaves the ground (liftoff); &lt;em&gt;50 ft&lt;/em&gt; is the ground roll + the distance to climb to 50 ft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;See also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/5060/what-would-be-the-ground-roll-and-total-distance-to-clear-a-50ft-obstacle-given&quot;&gt;What would be the ground roll and total distance to clear a 50ft obstacle given these conditions?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/3564/how-is-minimum-runway-length-related-to-v1&quot;&gt;How is minimum runway length related to V1?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-03-19T09:35:27.380" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26271" PostTypeId="1" AcceptedAnswerId="26296" CreationDate="2016-03-18T23:42:32.660" Score="8" ViewCount="3750" Body="&lt;p&gt;Recently on a trip to Orlando on Sun Country, I came across a cabin chime that I'd not heard before. It sounded like two 'high-low chimes' in a row, so basically equivalent to someone ringing a doorbell twice. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that one 'high-low' means that the FAs are speaking to each other through the phone in the aircraft, but I've never heard it twice in rapid succession. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are all 737-800s equipped with these chimes? What do they mean?  &lt;/p&gt;&#xA;" OwnerUserId="14043" LastEditorUserId="753" LastEditDate="2018-11-03T21:22:34.467" LastActivityDate="2018-11-03T21:22:34.467" Title="What does two 'high-low' chimes in the cabin of a 737-800 mean?" Tags="&lt;airliner&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26273" PostTypeId="1" CreationDate="2016-03-19T15:07:15.267" Score="2" ViewCount="200" Body="&lt;p&gt;For complex aircraft, I had always been taught to begin the before landing checklist, or the gear down before landing checklist, abeam the touchdown point, which for me is normally the thousand foot markers. However, I recently heard a DPE say to begin the checklist at midfield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is the appropriate method? There could be many opinions offered on this; however, opinions aside, what might be the considerations that would lead to beginning the checklist sooner? Is there a prescribed point to begin the checklist that I have overlooked, for example in the Practical Test Standards or elsewhere?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="12720" LastEditDate="2016-03-19T17:09:42.460" LastActivityDate="2016-03-19T17:09:42.460" Title="Is it better to begin the gear down before landing checklist abeam the touchdown point or midfield?" Tags="&lt;landing&gt;&lt;checkride&gt;&lt;checklist&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-03-29T13:28:25.910" ContentLicense="CC BY-SA 3.0" />
  <row Id="26274" PostTypeId="1" CreationDate="2016-03-19T17:21:33.003" Score="0" ViewCount="406" Body="&lt;p&gt;We know that every rotating device generates torque . How does a single engine propeller A/C (Piper) counter-balance the torque which is being produced by nose propeller?&lt;/p&gt;&#xA;" OwnerUserId="12245" LastEditorUserId="12245" LastEditDate="2016-03-19T19:44:20.220" LastActivityDate="2016-03-19T19:44:20.220" Title="Propeller Torque" Tags="&lt;propeller&gt;&lt;engine&gt;&lt;aircraft-physics&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2016-03-19T18:13:03.433" ContentLicense="CC BY-SA 3.0" />
  <row Id="26275" PostTypeId="2" ParentId="26274" CreationDate="2016-03-19T17:35:46.467" Score="1" Body="&lt;p&gt;Using the ailerons on the wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The torque is a roll moment and the ailerons will be able to counteract that easily.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2016-03-19T17:35:46.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26276" PostTypeId="1" CreationDate="2016-03-19T19:04:05.657" Score="14" ViewCount="1537" Body="&lt;p&gt;I noticed some dots and lines on the Boeing 747 engine pylons. What are they?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hEmYm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hEmYm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The above image is as seen in this &lt;a href=&quot;https://youtu.be/Ul7LE_oWdHw?t=138&quot; rel=&quot;nofollow noreferrer&quot;&gt;video at 2:18&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="14897" LastEditDate="2018-06-09T16:39:48.603" LastActivityDate="2018-06-09T16:39:48.603" Title="What are those things on the B747 engine pylons?" Tags="&lt;boeing-747&gt;&lt;engine-design&gt;&lt;feature-identification&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26277" PostTypeId="1" AcceptedAnswerId="26281" CreationDate="2016-03-19T21:10:50.750" Score="27" ViewCount="4841" Body="&lt;p&gt;If you look at &lt;a href=&quot;http://www.airliners.net/photo/0777717/L&quot; rel=&quot;noreferrer&quot;&gt;this picture&lt;/a&gt;, you'll see that the horizontal stabilizer has a very pronounced dihedral in comparison to the wings. Could somebody explain in a simple way why? I understand that a dihedral wing makes an aircraft more stable on the roll axis, but why on the horizontal stabilizer, which produces a downforce?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is not just about the DC-10, because there are also other planes that are not trijets and have this feature, I just used the DC-10 as an example&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also this schematic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2bZxQ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2bZxQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;Image excerpted from &lt;a href=&quot;https://en.wikipedia.org/wiki/File:DC10-30v1.0.png&quot; rel=&quot;noreferrer&quot;&gt;original&lt;/a&gt;, by Julien.scavini, used under &lt;a href=&quot;https://creativecommons.org/licenses/by-sa/3.0/deed.en&quot; rel=&quot;noreferrer&quot;&gt;CC BY-SA 3.0&lt;/a&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-01-13T00:20:28.107" LastActivityDate="2019-01-13T00:20:28.107" Title="Why does the DC-10's horizontal stabilizer have such a pronounced dihedral?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;horizontal-stabilizer&gt;&lt;dc-10&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26278" PostTypeId="2" ParentId="1106" CreationDate="2016-03-20T02:09:32.100" Score="4" Body="&lt;p&gt;Ahaha!! There IS in fact a non-ultralight aircraft out there that has its ONLY brake on the retractable nosewheel. That aircraft is the Verhees Delta. Uniquely, that aicraft has only two wheels (tandem, or bicycle undercarriage) and they are in line, one wheel at the front, retractable, and another, same size, 9 feet further aft, at the rear of the aircraft. There is a small bumper wheel at the tip of each wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft lands on the rear wheel - (the nose is very high, during landing as this is a delta wing aircraft). When it has slowed down enough the nosewheel leg makes contact with the runway and it can begin braking.&lt;/p&gt;&#xA;" OwnerUserId="14088" LastActivityDate="2016-03-20T02:09:32.100" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26279" PostTypeId="1" AcceptedAnswerId="26280" CreationDate="2016-03-20T05:09:17.760" Score="48" ViewCount="19274" Body="&lt;p&gt;If a pilot makes a mistake and inadvertently touches the gear up lever, will it actually activate while on the ground and make the plane drop onto its belly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suppose that there would be some sensor to prevent this, but I would like clarification on that.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="12220" LastEditDate="2016-03-20T11:46:25.227" LastActivityDate="2017-06-01T19:09:28.643" Title="Can the landing gear be pulled up while the plane is on the ground?" Tags="&lt;landing-gear&gt;" AnswerCount="3" CommentCount="14" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26280" PostTypeId="2" ParentId="26279" CreationDate="2016-03-20T05:39:06.897" Score="51" Body="&lt;p&gt;There is a weight sensor which senses if the plane is on the ground. This sensor prevents gear retraction while the plane is still on the ground. Failure of this sensor would prevent gear retraction after takeoff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you note closely, the landing gears (even the non-retractable ones) are not connected using a simple metal pole; rather, there is &lt;a href=&quot;https://en.wikipedia.org/wiki/Oleo_strut&quot; rel=&quot;nofollow noreferrer&quot;&gt;an oleo strut&lt;/a&gt; which is compressed by the weight of the aircraft. Besides airborne / ground detection, the struts absorb the vertical energy during touchdown.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/woIW6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/woIW6.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recall some decades ago engineers experimented obtaining the plane's gross weight by installing weight scales to each landing gear (as opposed to just an air/ground detection). The readings were found to be inaccurate and they soon abandoned the idea.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Landing gear stories cannot be complete without mentioning this incident in 1990:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A training captain of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_340&quot; rel=&quot;nofollow noreferrer&quot;&gt;Saab 340&lt;/a&gt; was betting with his students that the weight-on-gear mechanism would prevent gear retraction while on the ground. On the accident airplane type, the mechanism would lock the gear handle, but the lock can be overridden if the pilot manually pull out and move the handle. The instructor confidently pulled out the handle and to his surprise, the hydraulics started to move and the gears were retracted while the plane was still on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nQ9uz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nQ9uz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.airliners.net/photo/Crossair/Saab-Fairchild-SF-340A/648419/L&quot; rel=&quot;nofollow noreferrer&quot;&gt;image source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft was written off. This incompetent instructor pilot was killed 11 years later in &lt;a href=&quot;https://en.wikipedia.org/wiki/Crossair_Flight_3597&quot; rel=&quot;nofollow noreferrer&quot;&gt;another accident&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="7494" LastEditDate="2017-06-01T19:09:28.643" LastActivityDate="2017-06-01T19:09:28.643" CommentCount="23" ContentLicense="CC BY-SA 3.0" />
  <row Id="26281" PostTypeId="2" ParentId="26277" CreationDate="2016-03-20T11:54:01.017" Score="13" Body="&lt;p&gt;In a general sense, there are multiple reasons for the horizontal stabilizer to have dihedral/anhedral.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To clear the tail from the downwash/propwash. A good example is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_425&quot;&gt;Cessna 425&lt;/a&gt;, which was developed from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_421&quot;&gt;Cessna 421&lt;/a&gt;. The 421 had a straight horizontal stabilizer. However, with the addition of dihedral, the tail is kept out of the propwash, improving ride quality. From a report &lt;a href=&quot;http://compair.aviationresearch.com/database_files/TheImage_160.pdf&quot;&gt;citing Cessna engineers&lt;/a&gt;:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Cessna engineers say the dihedral improves Dutch roll qualities and moves a major portion of the tail out of the prop wash, thus providing a smoother ride.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Falcon_50&quot;&gt;Dassault Falcon 50&lt;/a&gt; had anhedral so as to clear the tail from the wing's downwash. Another good example of this is the F-4 Phantom. The prototypes had a straight tail. However, the anhedral tail was adopted so as to keep it clear of the disturbed air from the wing at high angles of attack while at the same time keeping it out of engine exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The anhedral in BAE Hawk is explained by the same reason. From &lt;a href=&quot;http://aerosociety.com/Assets/Docs/Publications/The%20Journal%20of%20Aeronautical%20History/2013-01_HawkStory-Fraser-Mitchell.pdf&quot;&gt;The Hawk Story&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This model gave the first indications of high speed problems due to interference between the high intake and the low wing, and the &#xA;  position of the tail.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;This resulted in the adoption of a low intake, ... .The rear fuselage was cambered downwards  to bring the tail down, and the tailplane was &#xA;  given pronounced anhedral for the same purpose. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Stability- The dihedral/anhedral in the stabilizers affects the aircraft's stability. In short, for a conventional tail, an anhedral improves the yaw stability of the aircraft while reducing the pitch stability (slightly), while a dihedral will reduce the tail's contribution to both pitch and yaw stability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the use of dihedral in the horizontal tail influences static roll stability in the same way as that of dihedral in the wing. Dihedral affects the roll response in the same way as that of the wing- it causes the lift on the right and left semispans to respond differently to downwash.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A good example of this is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_Viscount&quot;&gt;Vickers Viscount&lt;/a&gt;, which had a dihedral horizontal stabilizer, which improved its stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, it is better for the designer to add a dihedral to the horizontal tail rather than wing especially if problems are found in later stages of design as the impact will be lesser.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;From Roskam's Aircraft Design Vol III, Chapter 5.1:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The overall lateral stability is usually dominated by the inherent lateral stability designed into the wing. Wing sweep, dihedral angle and (wing) location on the fuselage dominate the magnitude and the sign of the stability derivative. Since the wing is designed by performance and operational considerations, &lt;strong&gt;the empennage is often used to fine tune the lateral stability of the aircraft&lt;/strong&gt;. Examples include the F-4 and the AV-8B.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It should be noted that, as with any other design consideration, the dihedral of the horizontal stabilizer depends on the design choices made and perfomance characteristics required; as a result, the configuration required will change from aircraft to aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case of DC-10, the main reason appears to be to keep the stabiliser out of the wing influence, especially when high flap settings are used. The more pronounced dihedral (compared to, say Boeing 737) appears to be used as the stabilizer is mounted lower due to the presence of engine in the tail.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-20T11:54:01.017" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26282" PostTypeId="2" ParentId="26277" CreationDate="2016-03-20T11:55:08.087" Score="12" Body="&lt;p&gt;Most airliners with low horizontal tail surfaces have dihedral on them, for two reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;To lift the horizontal surface above the wing wake.&lt;/li&gt;&#xA;&lt;li&gt;To lift the swept tail above the ground, so it will not be damaged in a &lt;a href=&quot;https://aviation.stackexchange.com/questions/14647/how-do-manufacturers-engineer-their-aircraft-to-deal-with-tail-strikes&quot;&gt;tail strike&lt;/a&gt;. Note that the tail is roughly horizontal at the tail strike attitude to have enough clearance for full down elevator deflection.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5s5Xf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5s5Xf.jpg&quot; alt=&quot;Boeing 747-400 tailstrike&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-400 tailstrike (picture &lt;a href=&quot;https://virtualmystic.files.wordpress.com/2010/05/ua-747-tailstrike.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g5lnh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g5lnh.jpg&quot; alt=&quot;Scrapped tail of a VC-10&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given enough angle of attack, a swept, un-dihedraled tail surface will touch the ground with the tips first (picture &lt;a href=&quot;http://www.vc10.net/History/Images/VM_tail_scrap.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a T-tail, both reasons don't exist, so T-tails are straight in most cases. A notable exception would be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_Victor&quot; rel=&quot;nofollow noreferrer&quot;&gt;Handley-Page Victor&lt;/a&gt;, where a noticeable dihedral was added late in the design process to increase the projected side area of the tail section. Thanks to @ymb1 for finding &lt;a href=&quot;https://www.flightglobal.com/pdfarchive/view/1959/1959%20-%202812.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt; which includes a detailed description of the Victor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vertical area is &lt;strong&gt;always&lt;/strong&gt; too small initially, just witness the tail growth in the BAC Lightning. Interestingly enough, the article says that the vertical on the Victor was &lt;strong&gt;shortened&lt;/strong&gt; after flight test. This is an extremely rare occurrence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DH06W.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DH06W.jpg&quot; alt=&quot;Handley-Page Victor&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Handley-Page Victor (picture &lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/photos/4/7/9/1876974.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="14897" LastEditDate="2018-01-13T01:06:12.250" LastActivityDate="2018-01-13T01:06:12.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26283" PostTypeId="1" AcceptedAnswerId="26345" CreationDate="2016-03-20T14:22:12.787" Score="10" ViewCount="3687" Body="&lt;p&gt;The cabin pressure controller controls the pressure in the cabin in relation with aircraft altitude, and a manual control is possible using the overhead panel:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A320&lt;/strong&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/pB5Ua.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pB5Ua.jpg&quot; alt=&quot;Air Conditioning and Cabin Pressure panels A320&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Air Conditioning and Cabin Pressure panels on an Airbus A320 (source: &lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Overhead_panel_of_an_Airbus_A320_during_cruise.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Olivier Cleynen on Wikimedia&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;B737&lt;/strong&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Cy7f8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cy7f8.jpg&quot; alt=&quot;Pressurization panel B737 NG&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Pressurization panel on a Boeing 737 NG (source: &lt;a href=&quot;http://www.b737.org.uk/pressurisation.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;B737.org.uk&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall how do the controller and the related equipment work in a commercial airliner, e.g:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the source used for pressure reference?&lt;/li&gt;&#xA;&lt;li&gt;How outflow and relief valves and packs are related to the controller?&lt;/li&gt;&#xA;&lt;li&gt;When and how is used the manual control of the pressure?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-22T14:12:14.330" LastActivityDate="2019-12-07T09:10:46.873" Title="How does the cabin pressure controller work in a large commercial airliner?" Tags="&lt;aircraft-design&gt;&lt;cabin-pressure&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26287" PostTypeId="2" ParentId="8289" CreationDate="2016-03-20T16:50:20.503" Score="0" Body="&lt;p&gt;There is no single normal descent rate in fpm. It varies widely.&#xA;A normal descent clearance only requires at least 500fpm. Unless ATC gives a hurry/expedite command.&#xA;For most of the explanation I assume an idle thrust descent, without an emergency or any reason to waste energy on purpose. A normal descent is almost a glide, with the engines producing minimum idle thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that scenario, descent rate is largely proportional to TAS (true airspeed).&#xA;So when the descent begins, say from a Mach 0.78 (250kias/450ktas) cruise, descent rate should be around 2500fpm.&#xA;This rate of descent should be maintained until transition from Mach to IAS happens. At that point the lower the aircraft goes, the slower the TAS will be, as a consequence, the descent rate will slow down proportionately.&#xA;At the same time, idle thrust at high altitude is quite low. The lower the aircraft goes, the higher idle thrust will be, further moderating descent rate.&#xA;In many jurisdictions there's a 250kias limit, so the descent rate should reduce a lot 11500 and 10000 to slow down from around 280kias to 250kias, since the true airspeed reduced, so will the descent rate.&#xA;Assuming no further speed restrictions, pilot should keep 240-250kias (resulting in about 1300fpm down) until entering the base leg or in the case of a straight in approach around 15nm final. At that point the aircraft should be gear down and rapidly transition to final approach flaps and final approach speed, again, true air speed reduces again, so does rate of descent, assuming a 140kias final, this should lead to around 700fpm descent.&#xA;A 3000fpm descent could happen if ATC assigns an altitude restriction, and the pilot trade airspeed for altitude in idle/low thrust, until a minimum safe speed is achieved. Once ATC clears the aircraft to continue its descent, the pilot can trade altitude for airspeed which would result in higher sink rate for a few minutes until the aircraft accelerates back to cruise descent.&#xA;If the pilot is too high or is given a hurry through descent clearance, it can deploy spoilers and/or lower the landing gear which could result in a 4000fpm descent.&#xA;Some congested airspace calls for quick descents to avoid invading climb/descent areas for other airports.&#xA;There's this saying that speed breaks is for pilot's mistakes, but not for ATC's mistakes... That's not a good wisdom. If you don't cooperate with ATC, you might find yourself in a hold or unnecessary detour for your lack of compliance. What might look like a mistake for a pilot might be unavoidable for ATC (for instance short staffed for a few minutes).&lt;/p&gt;&#xA;" OwnerUserId="14094" LastActivityDate="2016-03-20T16:50:20.503" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26289" PostTypeId="1" AcceptedAnswerId="26307" CreationDate="2016-03-20T20:47:53.197" Score="14" ViewCount="1952" Body="&lt;p&gt;Ice forms on the wings and instrument probes and vanes, but why not on the fuselage? If the temperature of the air is the same, why does the ice form on the wing but not on the fuselage?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="487" LastEditDate="2016-03-21T22:35:40.347" LastActivityDate="2016-03-24T01:25:35.750" Title="Why doesn't ice form on the fuselage?" Tags="&lt;aerodynamics&gt;&lt;icing&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26290" PostTypeId="2" ParentId="26279" CreationDate="2016-03-20T20:52:06.873" Score="18" Body="&lt;p&gt;This incident was &quot;half on ground&quot; during takeoff:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last year, the copilot of a Dash 8 applied erroneously the gear lever during takeoff as the rear gear had still ground contact. This resulted in a tail strike. The aircraft bounced back on runway 9 of Saarbrücken's airport, slipped some hundred meters and will be written off as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See the &lt;a href=&quot;http://www.bfu-web.de/DE/Publikationen/Bulletins/2015/Bulletin2015-09.pdf?__blob=publicationFile&quot;&gt;report of the German aviation authority&lt;/a&gt;, pages 60-76. It turns out that the Dash 8 has a weight-on-wheels sensor only on the front gear. The report says that the design responsible called this to &quot;comply with the design logic&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Differently from the incident @kevin mentioned, the gear doors were already closed as the fuselage touched ground.&lt;/p&gt;&#xA;" OwnerUserId="14099" LastEditorUserId="14099" LastEditDate="2016-03-20T22:13:19.577" LastActivityDate="2016-03-20T22:13:19.577" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26292" PostTypeId="2" ParentId="22495" CreationDate="2016-03-20T21:21:50.540" Score="3" Body="&lt;p&gt;Heavy helicopters tend to be hydraulicly controlled to such an extent that there no longer is a physical link between the controls and the blades (like big jets). You're just opening and closing hydraulic valves one way or another. So... no hydraulics, no controls. The hydraulic pumps are generally driven by the main gearbox so that you will always have hydraulic pressure (main and backup) as long as the rotors are turning faster than a minimum speed. Usually you will fall out of the sky before that rotor speed falls below that threshold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a rotor speed that if it falls below that rpm, you will have lost the ability to get it back up and will have lost the ability to auto rotate.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2016-03-20T21:21:50.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26293" PostTypeId="2" ParentId="26279" CreationDate="2016-03-20T21:49:42.873" Score="8" Body="&lt;p&gt;Safety standards have improved since the 1940s, but soon after a £1m restoration project on a WWII Spitfire, somebody blocked the runway at a local airport by demonstrating this design flaw. Apparently the pilot got confused about which of two levers retracted the flaps, and which retracted the landing gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The accident happened just before sunset, so I don't think there are any good pictures available on the web that show the damage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.bbc.co.uk/news/uk-england-leicestershire-22474805&quot;&gt;http://www.bbc.co.uk/news/uk-england-leicestershire-22474805&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/5422ed3640f0b6134200014f/Vickers_Supermarine_Spitfire_MK_XIX__G-RRGN_5-2013.pdf&quot;&gt;https://assets.digital.cabinet-office.gov.uk/media/5422ed3640f0b6134200014f/Vickers_Supermarine_Spitfire_MK_XIX__G-RRGN_5-2013.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2016-03-20T21:49:42.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26294" PostTypeId="6" CreationDate="2016-03-20T23:38:50.937" Score="0" Body="&lt;p&gt;I've been a PPL student for just over a year, and active on the site throughout that time. Although I haven't been as prolific on this site as some other parts of SE, I love the aviation.SE community because there is so little moderation needed on the site: we have a good team of active, high-rep users and hardly any 1-rep fly-by-nights (most of those were looking for travel.SE anyway). I feel that Aviation breaks the SE mould of &quot;for SO users who also like x&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to use the diamond to help set a more visible example of being a good citizen: assuming good faith, being encouraging to new visitors even when they're posting ELI5 questions or dangerous guesswork answers. Our community is doing so well, I'd like to challenge every member to be the best they can be: to delete that snarky comment before pressing enter, to spend an extra moment finding a source or a good (and public-domain!) picture, to research their own question and then post the answer too. This way we can remain a moderation-light site as we grow, and become an example to other SE sites of what it looks like when it works well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My favourite button in the review queues is &quot;skip&quot;, and I hope to keep it that way.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2016-03-20T23:38:50.937" LastActivityDate="2016-03-20T23:38:50.937" CommentCount="1" CommunityOwnedDate="2016-03-20T23:38:50.937" ContentLicense="CC BY-SA 3.0" />
  <row Id="26295" PostTypeId="1" AcceptedAnswerId="51408" CreationDate="2016-03-21T00:34:43.237" Score="13" ViewCount="1818" Body="&lt;p&gt;Approach plates include frequencies in the order that pilots will require them, reading from left to right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The example below from McClellan-Palomar’s ILS or localizer/DME approach to runway 24 is a fair representative. On the far right hand side just above the overhead view is the clearance delivery frequency of 134.85.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Talking to clearance delivery prior to &lt;em&gt;departure&lt;/em&gt; is common, but when would a pilot talk to clearance delivery on arrival? What is the purpose of including this frequency on the approach plate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hrqUd.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hrqUd.png&quot; alt=&quot;ILS or LOC/DME RWY 24 KCRQ&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2018-05-11T11:36:27.387" LastActivityDate="2020-02-10T21:36:08.007" Title="Why is the clearance delivery frequency included on an approach plate?" Tags="&lt;instrument-flight-rules&gt;&lt;approach&gt;&lt;aeronautical-charts&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26296" PostTypeId="2" ParentId="26271" CreationDate="2016-03-21T01:22:15.217" Score="10" Body="&lt;p&gt;As far as I know, the chimes work the same on all 737 NG (and Classic) versions, although as was mentioned in comments, how they are employed will vary from airline to airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two tone &quot;high-low&quot; chime described in the OP is the &quot;crew call&quot; system. The pilots have a button, the forward F/A station has one, and the aft F/A station has one.  Regardless of which button is pushed, the &quot;hi-low&quot; chime is the same.  In many, though not all, cases, this chime is a signal to the F/A's to answer the interphone.  If the pilots press their button, they're asking to speak to the F/A's; if one F/A station presses the button, they're asking to speak to the &lt;em&gt;other&lt;/em&gt; F/A station.  (They can also press a different button that calls the cockpit, but passengers won't hear that chime. In the cockpit, we hear that &quot;call&quot; as the two-tone chime; we don't hear the chimes in the cabin unless we're listening to PA audio.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At one carrier, a single high-low chime may mean &quot;answer the interphone,&quot; while at another carrier, one chime might be used to mean &quot;secure the cabin&quot; while two chimes is &quot;answer the interphone,&quot; three chimes is &quot;answer the interphone - urgent,&quot; and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll also hear chimes when the F/A Call Button above a passenger row is pressed; this is a distinct chime (a single, relatively high note).  There is also a chime when the Fasten Seatbelt sign is turned on or off, this is again distinctive, a single lower note.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that you won't necessarily hear the chimes when the interphone is in use; it's simply a &quot;Hey!&quot; call to the Flight Attendants in the cabin.  While it's often followed by a conversation on the interphone, they two are separate systems and one can be used without the other.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-21T01:22:15.217" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26298" PostTypeId="1" AcceptedAnswerId="26299" CreationDate="2016-03-21T03:43:46.260" Score="5" ViewCount="1864" Body="&lt;p&gt;Air traffic control (ATC) can issue a standard terminal arrival route (STAR) to aircraft entering the terminal environment. The STAR usually communicates a predefined route of flight (fix1, fix2, fix3, etc.). The STAR procedure usually includes altitudes too.&#xA;What will I hear from a controller when I am to follow the vertical guidance on the STAR vs. waiting for assigned altitudes?&lt;/p&gt;&#xA;" OwnerUserId="12288" LastActivityDate="2016-03-21T08:22:40.840" Title="How do I know if an arrival procedure (STAR) clearance includes altitudes?" Tags="&lt;instrument-procedures&gt;&lt;clearance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26299" PostTypeId="2" ParentId="26298" CreationDate="2016-03-21T04:23:22.560" Score="8" Body="&lt;p&gt;In the U.S., the phrase &quot;&lt;em&gt;Descend via&lt;/em&gt; the (arrival)&quot; means that you are cleared to the altitudes as published.  Without that phrase, simply cleared for the ___ arrival, then your clearance is the fixes, but ATC will assign your altitude explicitly. In this case, the published altitudes may later be assigned, so descent planning should still be based on making the next fix at its altitude. You just don't go below your assigned altitude until cleared lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA Explanations:&#xA;Starting on page 8 for &quot;descend via&quot; clearances: &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/pbn/media/rnav1_rnp1_rnav2/climb_descend_via_faq.pdf&quot;&gt;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/pbn/media/rnav1_rnp1_rnav2/climb_descend_via_faq.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More succinctly: &lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2014/InFO14003.pdf&quot;&gt;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2014/InFO14003.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-21T04:23:22.560" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26300" PostTypeId="2" ParentId="26298" CreationDate="2016-03-21T08:22:40.840" Score="3" Body="&lt;p&gt;ICAO phraseology has the same phraseology for being cleared for arrivals:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;.724  Freigaben auf Einflugstrecken &#xA;Clearances on a STAR &#xA;&#xA;G: DESCEND VIA (designator) (level) &#xA;G: DESCEND VIA (designator) (level) CANCEL LEVEL / &#xA;   SPEED RESTRICTION(S) *AT (significant point)* &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The phraseology for transitions is different from this:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;   RNAV phraseologies &#xA;&#xA;G: CLEARED (designator) TRANSITION &#xA;G: CLEARED (designator) TRANSITION AND PROFILE &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The interesting part about STARs however is: Even when cleared to descend to a flight level or altitude after previously being assigned a STAR, the altitude restrictions of the STAR are in effect until cancelled by the air traffic control unit, as referenced above, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The waypoint EXMPL has a lower restriction (minimum restrictions of FL100) and you are cleared to descend via the STAR to FL70, the fix still needs to crossed at or above FL100, &lt;a href=&quot;http://www.skybrary.aero/bookshelf/books/973.pdf&quot; rel=&quot;nofollow&quot;&gt;unless that restriction is cancelled with above phraseology&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2016-03-21T08:22:40.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26301" PostTypeId="5" CreationDate="2016-03-21T09:53:16.023" Score="0" Body="&lt;p&gt;This tag should be used for questions related to the Garmin GNS430 and GNS430W integrated avionics system. The GNS 430 and GNS 430W are integrated avionics systems providing comm/nav radio functionality and GPS navigation.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-21T10:12:30.590" LastActivityDate="2016-03-21T10:12:30.590" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26302" PostTypeId="4" CreationDate="2016-03-21T09:53:16.023" Score="0" Body="Questions related to the Garmin 430" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-21T10:36:28.893" LastActivityDate="2016-03-21T10:36:28.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26303" PostTypeId="5" CreationDate="2016-03-21T09:57:55.703" Score="0" Body="&lt;p&gt;This tag should be used for questions related to the Garmin GNS430 and GNS430W integrated avionics system. The GNS 430 and GNS 430W are integrated avionics systems providing comm/nav radio functionality and GPS navigation.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-21T10:11:53.430" LastActivityDate="2016-03-21T10:11:53.430" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26304" PostTypeId="4" CreationDate="2016-03-21T09:57:55.703" Score="0" Body="Questions related to the Garmin 430" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-21T10:36:11.473" LastActivityDate="2016-03-21T10:36:11.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26306" PostTypeId="6" CreationDate="2016-03-21T10:25:37.270" Score="0" Body="&lt;p&gt;I would like help the community as a moderator. As many of the others have pointed out, moderators are service people. We are not here to mod and edit every post, the community already does a great job and reviews the queues. Moderators are as voretaq already pointed out: janitors. We grease the gears and we tidy up the place, but usually do that in the background.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have been with the community for some 2 years, have participated in the blog that unfortunately lost momentum and I am quite knowledgeable in some fields of aviation: General Aviation, Air Traffic Control, EASA Regulations and I own a PPL with roughly 100h+ of flight time. I also control on the simulation network VATSIM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SentryRaven for &lt;s&gt;president&lt;/s&gt; moderator!&lt;/p&gt;&#xA;" OwnerUserId="572" LastEditorUserId="572" LastEditDate="2016-03-21T10:25:37.270" LastActivityDate="2016-03-21T10:25:37.270" CommentCount="0" CommunityOwnedDate="2016-03-21T10:25:37.270" ContentLicense="CC BY-SA 3.0" />
  <row Id="26307" PostTypeId="2" ParentId="26289" CreationDate="2016-03-21T10:34:43.223" Score="16" Body="&lt;p&gt;It does, but there is much less of it on the fuselage than on the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two ways how ice is accumulated on the aircraft's structure:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When flying through air containing &lt;a href=&quot;https://en.wikipedia.org/wiki/Supercooling&quot; rel=&quot;nofollow noreferrer&quot;&gt;supercooled water droplets&lt;/a&gt;, the water will freeze on impact. It does not make much of a difference whether the water impacts the fuselage nose or the leading edge of the wings and tail surfaces: It will form a sheet of clear ice.&lt;/li&gt;&#xA;&lt;li&gt;When flying through moist air at a temperature close to freezing, the &lt;a href=&quot;https://aviation.stackexchange.com/questions/23676/why-would-a-canard-wing-be-more-prone-to-icing-than-a-stabilizer/23686?s=1%7C0.3346#23686&quot;&gt;pressure loss of the air flowing around any obstacle&lt;/a&gt; will &lt;a href=&quot;https://aviation.stackexchange.com/questions/14327/what-is-the-mechanism-by-which-condensation-forms-above-wings/14331?s=2%7C0.0978#14331&quot;&gt;cool it down&lt;/a&gt;, so the moisture condenses and, if temperature allows, will form ice accumulations. Those in turn exacerbate the suction peaks, leading to more ice being collected.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The wing's leading edge shows the most pronounced suction peaks, so they will collect most ice. However, if the icing conditions are right, the fuselage nose will also pick up it's share of ice. Along the length of the fuselage, pressure is similar to ambient, so it will collect ice only when sitting on the ground in freezing rain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SejoX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SejoX.jpg&quot; alt=&quot;Iced engine nacelle in the NASA icing research tunnel&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Iced engine nacelle in the NASA Lewis (now Glenn) Research Center icing research tunnel (picture &lt;a href=&quot;http://www.nasa.gov/multimedia/imagegallery/image_feature_464.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Here, water is sprayed into the tunnel and forms supercooled droplets.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both cases icing has nothing to do with the boundary layer - with supercooled water it is simple ballistics, while the second case of ice accumulation is dominated by the pressure of the flow around the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-03-21T11:37:23.467" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26308" PostTypeId="2" ParentId="26289" CreationDate="2016-03-21T10:40:55.510" Score="4" Body="&lt;p&gt;In order to answer you properly I need to first introduce firstly the concept of boundary layer. When an airplane is flying over the air in normal conditions (I mean, usual high Reynolds number), the air flows cretes an small layer around the airplane that is call boundary layer (image source &lt;a href=&quot;http://web.cecs.pdx.edu/~gerry/class/ME322/notes/img/airfoilBoundaryLayer.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Portland State University&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zbB2U.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zbB2U.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The previous figure gives you an sketch of how is the boundary layer around an airfoil that is similar to the figure you will see around the airplane. Notice the following behaviours of the air:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The boundary layer grows downwash.&lt;/li&gt;&#xA;&lt;li&gt;The boundary layer is really thin at the beginning.&lt;/li&gt;&#xA;&lt;li&gt;The air flow (the inviscid flow...) follows the shape of the limit of the boundary layer, not the shape of the airfoil.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now, let's say the air contains some water drops. Depending on the size of the water drops they can behave following the air or like bullets following the an straight path. In the reallity the drops have an intermediate behavior, having some inertia and taking some time to adapt to the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Based on that, some drops following the streamlines of slighly over or down the airplane will almost follow the streamlines flying over the boundary layer and not pouring over the surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, some drops will impact directly over the surface of the airplane in what is called &quot;stagnation point&quot;, once over that surface they will behave like an humid surface moving in the air... the drops will expand along the surface and eventually leave the surface, in that process due to the air temperature and the surface heat exchange ratios some ice will be formed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the previous explanation we can understand why ice is not formed in the rear part of the fuselage, simply because the boundary layer is &quot;protecting&quot; it and the water accumulated in the front is simply not reaching the rear part.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to find locations where you can find ice in an airplane, just look for stagnations points (where the flow &quot;impacts&quot; in a simplified way) and the surrondings. Where do we have this areas?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Leading edges of wings (image source &lt;a href=&quot;https://www.google.es/url?sa=i&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=imgres&amp;amp;cd=&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwik1_XP-9fLAhWFAxoKHdKIDcsQjRwIBw&amp;amp;url=http%3A%2F%2Fwww.airdorrin.com%2F%3Fp%3D957&amp;amp;psig=AFQjCNEpUp54aqg-YCgMUkh2FHvNfr62Fw&amp;amp;ust=1458862276178771&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirDorrin&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yM2Vk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yM2Vk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Engine inlets ( image source &lt;a href=&quot;http://history.nasa.gov/SP-4306/p113.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d4j6r.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d4j6r.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Instruments (image source &lt;a href=&quot;https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTqg7atl1jSP3shFfqlYajD0m0U7On5vCSGmnPBlJptJSU5WeSYyQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;AviationWeather&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Rkxi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Rkxi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rarely front windows (image source  flyjoe180 at &lt;a href=&quot;http://rnzaf.proboards.com/thread/7844&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wings over new Zeland&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hIiNZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hIiNZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Front fuselage (did not find any picture).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course, having the airplane on ground removes the &quot;protection&quot; of the boundary layer, leaving the airplane exposed to any ice creation.&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="6979" LastEditDate="2016-03-24T01:25:35.750" LastActivityDate="2016-03-24T01:25:35.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26309" PostTypeId="1" AcceptedAnswerId="26311" CreationDate="2016-03-21T13:40:27.433" Score="38" ViewCount="23076" Body="&lt;p&gt;Is the force of gravity less on an airliner at cruise speed and altitude? I'm not talking about a special reduced gravity flight with a parabolic flight path, just a typical long distance flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems to me there should be less as passengers are further away from the centre of the earth, and also possibly a tiny effect from the speed the plane as it travels round the curve of the earth (altitude remaining constant) but does anybody actually know how much less?&lt;/p&gt;&#xA;" OwnerUserId="14109" LastEditorUserId="814" LastEditDate="2016-03-22T13:02:26.780" LastActivityDate="2016-10-20T14:23:13.390" Title="Is gravity less on an airliner at cruise altitude?" Tags="&lt;airliner&gt;&lt;theory&gt;" AnswerCount="7" CommentCount="12" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26310" PostTypeId="2" ParentId="26309" CreationDate="2016-03-21T14:06:32.330" Score="4" Body="&lt;p&gt;You are correct that the force of gravity is slightly less the further you get from the earth.   Airlines typically cruise around 30,000 - 35,000 feet.  We can use as a proxy measurement the force of gravity on Mt. Everest, which is 29,000 ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The force of gravity on Everest is about 0.434% less than the standard 9.8N/kg.  This means that one pound at Sea Level would weigh about 0.995 lbs. at 29,000 ft.   Or, a typical 180 lb. human would weigh 179.1 lbs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't consider the speed of the aircraft going around the earth to be significant.  Any centripetal force would be extremely tiny.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-03-21T14:06:32.330" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="26311" PostTypeId="2" ParentId="26309" CreationDate="2016-03-21T14:15:36.557" Score="43" Body="&lt;p&gt;There is less gravitational force, but by how much? An insignificant amount.&#xA;The gravitational force of attraction between two objects is given by,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\displaystyle F_{\mathrm g} = \frac{G m_{1} m_{2}}{R^2}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$G$ is the graviational constant,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R$ is the distance between the object's centers, and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$m_{1}$ and $m_{2}$ are the masses of the objects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead of finding the variation in force between the aircraft and earth, it would be be better to find the variation in the acceleration due to gravity, $g$ (as $F_{\mathrm g} = m_{\mathrm a} g$, with $m_{\mathrm a}$ being the mass of the airliner)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have, on earth's surface,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\displaystyle g = \frac{G m_{\mathrm e}}{R_{\mathrm e}^2}$ &lt;/p&gt;&#xA;&#xA;&lt;p&gt;where,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$m_{\mathrm e}$ is the mass of the earth, and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$R_{\mathrm e}$ is the radius of the earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the aircraft at an altitude $h$ above the surface of the earth, this becomes,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\displaystyle g_{h} = \frac{G m_{\mathrm e}}{\left(R_{\mathrm e} + h\right)^2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking ratio, we get,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\displaystyle \frac{g_{h}}{g} = \left(1 + \frac{h}{R_{e}}\right)^{-2}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plugging in numbers, we get, for an airliner cruising at 12 km,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$g_{h} = 9.773\ \mathrm{m\ s^{-2}}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or about 0.37 % less compared to the sea level value. This is quite small and would not be noticable to all but the sensitive instruments.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2016-10-20T14:23:13.390" LastActivityDate="2016-10-20T14:23:13.390" CommentCount="15" ContentLicense="CC BY-SA 3.0" />
  <row Id="26313" PostTypeId="2" ParentId="26309" CreationDate="2016-03-21T18:03:44.303" Score="2" Body="&lt;p&gt;Here's the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fermi_problem&quot; rel=&quot;nofollow&quot;&gt;Fermi Estimate&lt;/a&gt; version, in case the math in Aeroalias's answer is difficult to follow:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's been said that the ISS experiences 0.9 G (90% of standard gravity at sea level), which is of course canceled out by their orbital velocity so the astronauts inside feel like they're in 0G.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes are said to fly a mile high, and the ISS is over 100 miles high--these are not particularly accurate numbers, but they're good enough for order-of-magnitude estimations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, without any complicated math, we would expect an airplane to experience 99.9% of standard gravity.  As Aeroalias's answer works out to 99.63%, this is a pretty good estimate.&lt;/p&gt;&#xA;" OwnerUserId="4221" LastEditorUserId="4221" LastEditDate="2016-03-21T18:51:12.707" LastActivityDate="2016-03-21T18:51:12.707" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="26314" PostTypeId="2" ParentId="26295" CreationDate="2016-03-21T19:22:04.610" Score="0" Body="&lt;p&gt;If the aircraft is making a multi-hopped journey, then they will need a new clearance after they land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In that case they may begin talking to clearance delivery before they land or while they are taxiing.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-03-21T20:22:13.713" LastActivityDate="2016-03-21T20:22:13.713" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26315" PostTypeId="2" ParentId="26309" CreationDate="2016-03-21T19:39:17.330" Score="21" Body="&lt;h2&gt;Gravity itself&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;@aeronalias is absolutely right. &#xA;Given the gravitational acceleration of $g=9.81m/s^2$ on the ground, a perfect spherical earth of radius $R_E=6370km$ with homogenous (at least: radially symmetric) density, one can calculate the gravitational acceleration at an altitude of $h=12km$ by&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$g(h)=g\cdot\frac{R_E^2}{(h+R_E)^2}= 9.773 \rm{m}/s^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Expressed in terms of $g$, the difference is&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$g_\rm{diff} = 0.0368565736 m/s^2 = 0.003757g$$&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Centrifugal forces&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The question also asks for the centrifugal effect on the aircraft &lt;em&gt;as it travels round the curve of the earth&lt;/em&gt;, which has not yet been answered yet. The effect is considered small, but compared to the effect on gravity itself, it isn't always.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I got some heavy objections on my answer and I have to admit, I really don't see their point. Therefore, I've edited this section and hope this helps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, an object moving on a circular path experiences a centrifugal acceleration, pointing away from the center of the circle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a_c=\omega^2r=\frac{v^2}{r}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\omega=\frac{\alpha}{t}$ is the angular speed, i.e. the angle $\alpha$ (in radians) the object travels in a given time $t$ (in seconds).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's consider a &quot;perfect&quot; Earth as described above, plus no wind.&#xA;A balloon hovering stationary over a point at the equator at 12km altitude will do one revolution ($\alpha=2\pi[=360°]$) in 24 hours. So it is $\omega=\frac{2\pi}{24\cdot60\cdot60s}$. Together with $r=R_e+h$, one gets for the balloon:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a_{cb}=0.03374061 m/s² = 0.0034394098 g$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The circumference of the circle the balloon flies is $2\pi(R_e+h)=40099km$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider an aircraft flying east along the equator at the same altitude at 250m/s (900km/h, 485kt) with respect to the surrounding air. (Keep in mind: no wind). In 24h, this aircraft travels a distance of 21600km, or 0.539 of the circumference. This means the aircraft does 1.539 revolutions of the circle in 24h, which means its angular speed is  $\omega=1.539\cdot\frac{2\pi}{24\cdot60\cdot60s}$.&#xA;Thus, the centrifugal force on the aircraft flying east is&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a_\rm{ce} = 0.0799053814 m/s^2  =  0.0081452988 g$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same way, one can calculate what happens when the aircraft flies west:&#xA;$\omega=(1-0.539)\cdot\frac{2\pi}{24\cdot60\cdot60s}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$a_\rm{cw} = 0.0071833292 m/s^2   =   0.0007322456 g$$&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Comparison&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Let's write the values together to compare them. I've also added how much lighter a 100kg (220lb) person would feel due to the effects:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                                             | &quot;weight loss&quot;&#xA;g_diff = 0.0368565736 m/s²  = 0.003757 g     | 376gram (0.829lb)&#xA;a_cb   = 0.03374061   m/s²  = 0.0034394098 g | 344gram (0.758lb)&#xA;a_ce   = 0.0799053814 m/s²  = 0.0081452988 g | 815gram (1.797lb)&#xA;a_cw   = 0.0071833292 m/s²  = 0.0007322456 g |  73gram (0.161lb)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note:&lt;/strong&gt; The 100kg is what a scale at the North Pole (i.e. without any centrifugal effect) shows. The person already feels 344g lighter on the ground at the equator. The balloon doesn't change this (much).&#xA;But moving east/west has a larger effect on the weight than gravity alone. A person flying west feels even heavier than on ground!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe another table, showing the weight of the person:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                                             kg      lb&#xA;1. Man at north pole                       100.00  220.46&#xA;2. Man at equator                           99.66  219.70&#xA;3. Man at equator, in balloon               99.28  218.88&#xA;4. Man at equator, in aircraft flying east  98.81  217.84&#xA;5. Man at equator, in aircraft flying west  99.55  219.47 &amp;lt;- More than 3.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The numbers shown are only valid at the equator and for flights east / west. In other cases, it becomes a little more complex. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; Being curious on how this depends on latitude, I created this plot about the absolute acceleration an aircraft experiences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/07Tnq.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/07Tnq.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radius in the equation of the centrifugal force is the distance of the aircraft to the axis of the Earth. It is clear that it decreases when moving away from the equator, and so does the acceleration.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The speed of the aircraft flying west will cancel out the speed of the earth at about 57° N / S, i.e. there is no centrifugal force. At larger latitude, the aircraft will fly in the opposite direction around the axis of the earth, building up a centrifugal force again.&lt;br&gt;&#xA;Near the poles, both aircraft become  centrifuges (theoretically). E.g. flying a circle of 500m radius gives an acceleration of 12.7g. This is why the data rises to infinity there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(When doing the math, one has to keep in mind that gravity always points to the center of the earth, while the centrifugal force points away from the axis. You can't just add them)&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2016-03-24T09:01:10.887" LastActivityDate="2016-03-24T09:01:10.887" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="26316" PostTypeId="1" AcceptedAnswerId="26321" CreationDate="2016-03-21T20:01:26.613" Score="10" ViewCount="1409" Body="&lt;p&gt;I've seen the occasional Service Bulletin that is marked &lt;em&gt;Obsolete&lt;/em&gt;, and others that &lt;em&gt;Supersede SB-123&lt;/em&gt;. If I'm a pilot or A&amp;amp;P looking through logbooks, what resources are available to determine if a given SB still applies to the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, American SB-131 applies to AA-1, AA-1A, and AA-5 aircraft. However, &lt;a href=&quot;http://www.grummanpilotsassociation.com/wp-content/uploads/2015/01/SB-131.pdf&quot;&gt;this scan&lt;/a&gt; (pdf) seems to suggest that it's obsolete, and the contents are now in the service manual.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2016-03-21T20:12:49.647" LastActivityDate="2016-03-26T05:54:54.413" Title="How can one determine if a Service Bulletin is still applicable?" Tags="&lt;faa-regulations&gt;&lt;aircraft-maintenance&gt;&lt;airworthiness&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26317" PostTypeId="2" ParentId="17421" CreationDate="2016-03-21T21:03:31.667" Score="0" Body="&lt;p&gt;This was tried in the '50s by providing small flaps on the tires which caught the air and spun the tire prior to touchdown.  Medium and mixed success.  Don't know why it never caught on.&lt;/p&gt;&#xA;" OwnerUserId="14119" LastActivityDate="2016-03-21T21:03:31.667" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26318" PostTypeId="1" AcceptedAnswerId="26329" CreationDate="2016-03-21T21:40:54.257" Score="5" ViewCount="295" Body="&lt;p&gt;I understand that KSJC is a busy airport. I have done touch'n'gos at &lt;a href=&quot;https://skyvector.com/airport/OAK/Metropolitan-Oakland-International-Airport&quot; rel=&quot;nofollow&quot;&gt;Oakland&lt;/a&gt; (also a busy Class C airport), but they have three dedicated runways for GA aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There &lt;a href=&quot;https://skyvector.com/airport/SJC/Norman-Y-Mineta-San-Jose-International-Airport&quot; rel=&quot;nofollow&quot;&gt;is nothing&lt;/a&gt; about which runway is preferred for GA operations at SJC in the Airport Facility Directory notes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What should I expect if planning an unannounced trip to SJC (arriving from the north/north-east)? Are touch-n-goes tolerated (i.e. staying in the pattern)? Which runway should I expect to be directed to? Is there anything else I should know?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm looking for local knowledge from someone with experience flying in the area, for example &quot;GA operations are usually conducted on 30L, as the air carrier terminal is on the the other runway, and transient parking is adjacent to this runway&quot; [I'm not sure this is the case, this is just an example of the type of information I'm looking for].&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2016-03-21T23:02:43.010" LastActivityDate="2016-03-22T06:04:26.727" Title="What should I expect for an unannounced GA visit for touch-n-gos at San Jose?" Tags="&lt;airport&gt;&lt;general-aviation&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26319" PostTypeId="2" ParentId="26309" CreationDate="2016-03-21T22:13:02.897" Score="0" Body="&lt;p&gt;Most answers here are from a perspective of &quot;at a height of X, you weigh Y&quot;. Lets turn this around.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the altitude of the ISS, gravity is about 10% less. I doubt you'd notice 10% reduction in weight (double-blind, if such a thing were possible), without using measuring equipment. That's 400km up (250 miles), and well outside our atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason people are &quot;weightless&quot; on the ISS, is that they are in orbit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things in orbit are always weightless. The scales you are standing on is falling at the same speed you are. This can happen at any altitude - if you kick a ball, it is in orbit - an orbit that intersects with the surface of the earth, so it can't complete the orbit. &lt;/p&gt;&#xA;" OwnerUserId="14121" LastActivityDate="2016-03-21T22:13:02.897" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26320" PostTypeId="2" ParentId="26318" CreationDate="2016-03-21T22:46:36.380" Score="3" Body="&lt;p&gt;KSJC is a towered airport so you are at the discretion of the controller as to what runway you will be instructed to use as well as if touch and go's will be permitted at the time. This may be load dependent when you arrive. I would expect either runway and it all depends who is about to depart when you arrive.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gshMM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gshMM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While a typical pattern is the norm at a towered field it should be noted the controller may extend a leg or two to make room for other traffic. It should also be noted that according to the AFD 30R and and 12R have Right Traffic while the other runways will have left traffic so you should be alert of the pattern you are flying depending on the runway you are inbound for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since this airport is with in class C airspace (from the surface) you will also need to contact the appropriate controller to enter the airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should always get a flight brief before heading out to ensure that there are no active Notams or information you may need about the airport.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-22T01:57:56.580" LastActivityDate="2016-03-22T01:57:56.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26321" PostTypeId="2" ParentId="26316" CreationDate="2016-03-21T23:14:14.807" Score="5" Body="&lt;p&gt;This &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-176A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA AC outlines how SB's should be drafted&lt;/a&gt;. It also says that the Design Approval Holder should make available an easy way to search the SB's&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A DAH should develop a robust SB/AD tracking and management system&#xA;using the following process to ensure overlaps and conflicts between&#xA;new and existing SB actions are identified and addressed: a. Search&#xA;capabilities should include the following primary areas:&lt;/p&gt;&#xA;&lt;p&gt;(1)&#xA;Make/model or part number of affected product(s),&lt;/p&gt;&#xA;&lt;p&gt;(2) Major aircraft&#xA;elements (e.g., engine, strut, wing, etc.),&lt;/p&gt;&#xA;&lt;p&gt;(3) ATA code,&lt;/p&gt;&#xA;&lt;p&gt;(4)&#xA;Maintenance zones,&lt;/p&gt;&#xA;&lt;p&gt;(5) Service information (e.g., service bulletin&#xA;number),&lt;/p&gt;&#xA;&lt;p&gt;(6) Airworthiness limitation sections,&lt;/p&gt;&#xA;&lt;p&gt;(7) Previously issued&#xA;ADs, and&lt;/p&gt;&#xA;&lt;p&gt;(8) Planned ADs (i.e., action(s) that the FAA proposes to&#xA;mandate in an AD).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This puts the ownership on the company a bit.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgSAIB.nsf/MainFrame?OpenFrameSet&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA makes all current bulletins available here&lt;/a&gt; so you can check if they still list it as current.&lt;/p&gt;&#xA;&lt;p&gt;There is also a bit of duality between service bulletins and Air worthiness directives. SB's are issued by the company if they feel there is a safety hazard to the aircraft. Most importantly, unless they are issued alongside an AD they may not be mandatory. You can &lt;a href=&quot;http://blog.covingtonaircraft.com/2015/06/09/service-bulletins-and-airworthiness-directives/&quot; rel=&quot;nofollow noreferrer&quot;&gt;check out this blog post&lt;/a&gt; that goes into it a bit more.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-22T01:54:45.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26322" PostTypeId="1" AcceptedAnswerId="26323" CreationDate="2016-03-21T23:16:46.417" Score="2" ViewCount="4542" Body="&lt;p&gt;The inside back cover of the FAA Terminal Procedures Publication contains a table headed &amp;ldquo;CLIMB/DESCENT TABLE,&amp;rdquo; excerpted below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AUgvj.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AUgvj.png&quot; alt=&quot;FAA TPP Climb/Descent Table&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;&lt;b&gt;Source: &lt;a href=&quot;http://aeronav.faa.gov/d-tpp/1603/frntmatter.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA&lt;/a&gt;, p.&amp;nbsp;19&lt;/b&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do required ascent or descent per nautical mile and ground speed combine to give feet per minute? What is the relationship between the values in the two leftmost columns?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-03-22T01:08:54.840" LastActivityDate="2019-01-18T04:19:27.613" Title="How does the FAA compute the values in TPP's Climb/Descent Table?" Tags="&lt;aircraft-performance&gt;&lt;flight-planning&gt;&lt;performance-calculation&gt;&lt;descent&gt;&lt;climb&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26323" PostTypeId="2" ParentId="26322" CreationDate="2016-03-21T23:16:46.417" Score="2" Body="&lt;p&gt;Given a required climb or descent in feet per minute and ground speed in knots, compute the target VSI reading with &lt;em&gt;required climb/descent&lt;/em&gt; multiplied by &lt;em&gt;ground speed&lt;/em&gt; divided by sixty, or&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\delta_{VSI} = \frac{\mathrm{RCD} \times \mathrm{GS}}{60}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apply &lt;a href=&quot;https://en.wikipedia.org/wiki/Dimensional_analysis&quot; rel=&quot;nofollow noreferrer&quot;&gt;dimensional analysis&lt;/a&gt; to see why this works. Informally, we can think of nautical miles and hours in the numerator and denominator as canceling each other out to leave a figure in feet per minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;\delta_{VSI}\ \frac{\mathrm{ft}}{\mathrm{min}}&#xA;=&#xA;\mathrm{RCD}\ \frac{\mathrm{ft}}{\mathrm{nm}}&#xA;\times&#xA;\mathrm{GS}\ \frac{\mathrm{nm}}{\mathrm{hour}}&#xA;\times&#xA;\frac{\mathrm{1\ hour}}{\mathrm{60\ min}}&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fundamentally, trigonometry determines the values given angles in the leftmost column and the FAA&amp;rsquo;s definition of a nautical mile being 6,076.1 feet. In a right triangle, tangent is the ratio of the opposite leg to the adjacent leg for a given angle $\theta$, illustrated below for a climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/L0rdS.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/L0rdS.png&quot; alt=&quot;Figure: climbing at a certain angle over 1 NM&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the values in the table&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the adjacent leg is exactly 1 nautical mile&lt;/li&gt;&#xA;&lt;li&gt;the angle $\theta$ is the precise value from the leftmost column&lt;/li&gt;&#xA;&lt;li&gt;the opposite leg is unknown and is the desired ft/NM value&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The core formula is $6,076.1 \tan\theta$ for the ft/NM values, and this is the derivation of the values in the &lt;strong&gt;Vertical Path Angle&lt;/strong&gt; box outlined with a heavy border. Outside this box, the climb rates are rounded to the nearest multiple of 5. The rest of the table values use the $\delta_{VSI}$ formula above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, see a &lt;a href=&quot;https://docs.google.com/spreadsheets/d/15VIemi3Co9aoS933fqY1JreAxK1JBg1k3QtT2ZfB_A0/edit?usp=sharing&quot; rel=&quot;nofollow noreferrer&quot;&gt;Google spreadsheet that computes climb/descent rates&lt;/a&gt; using the above. The formula for altitude change for a climb or descent at 2.0° over 1 NM is of the form&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;=mround($O$1*tan(radians(B4)),5)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The value in &lt;code&gt;O1&lt;/code&gt; is the number of feet in one nautical mile. The trigonometric functions in Excel and Google Sheets deal in radians rather than degrees, where a complete circle has $2\pi$ radians.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The formula for the $\delta_{VSI}$ values in feet-per-minute is either&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;=mround(D$3*$C4/60,5)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;or&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;=D$3*$C6/60&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;depending on whether the cell is inside the Vertical Path Angle box, &lt;em&gt;i.e.&lt;/em&gt;, whether the value should be rounded to the nearest multiple of 5 or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are discrepancies, no more than 15 feet per minute. Some of the FAA figures are more conservative, some less. I was not able to discern a pattern; for details, see the color coding in the Computed sheet or the Deltas sheet in the &lt;a href=&quot;https://docs.google.com/spreadsheets/d/15VIemi3Co9aoS933fqY1JreAxK1JBg1k3QtT2ZfB_A0/edit?usp=sharing&quot; rel=&quot;nofollow noreferrer&quot;&gt;linked workbook&lt;/a&gt;. The odd duck is for a 2.0° climb at 210-knot ground speed: the FAA table gives an unrounded value of 743 feet per minute rather than rounding as with its neighbors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stack Exchange does not support tables in their Markdown flavor, so a screenshot of the computed table is below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O3Jd1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O3Jd1.png&quot; alt=&quot;Computed Climb/Descent Table&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-03-24T18:08:22.393" LastActivityDate="2016-03-24T18:08:22.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26327" PostTypeId="1" AcceptedAnswerId="26336" CreationDate="2016-03-22T03:01:58.507" Score="1" ViewCount="733" Body="&lt;p&gt;I am working on a game involving flying and steering a paper airplane for WP7. I want the plane to fly just like how normal paper airplanes (&lt;a href=&quot;http://armorgames.com/play/7598/flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;online game&lt;/a&gt;) but I can't seem to find an equation for how paper airplanes fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyone have any experience with this? In my game now, it just follows the usual motion for an object in a vacuum, which makes for some flight, but it doesn't feel perfect, and traveling at a slight downward angle makes you lose speed, which isn't right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I am asking do paper air planes have a maximum velocity brought on by its paper design even if control and thrust was possible maybe using composite cardboard material?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On Physics.SE: &lt;a href=&quot;https://physics.stackexchange.com/questions/9896/paper-airplane-physics&quot;&gt;Paper airplane physics&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user20435" LastEditorUserId="-1" LastEditDate="2017-04-13T12:40:14.990" LastActivityDate="2017-03-27T02:17:27.530" Title="How can I properly model paper airplane physics?" Tags="&lt;aircraft-design&gt;&lt;paper-airplane&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2016-03-22T08:57:22.700" ContentLicense="CC BY-SA 3.0" />
  <row Id="26328" PostTypeId="1" CreationDate="2016-03-22T06:02:19.617" Score="1" ViewCount="842" Body="&lt;p&gt;I was reading a question on Travel.SE. The asker was asking whether the time on his ticket was in Daylight Savings Time or in standard time. I would imagine flight schedules are supposed to be time-zone/DST agnostic so as to avoid any potential confusion and timezone conversions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A commenter mentioned UTC time, which makes sense to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So my question is: is there a standard time zone or other time standard used for tickets and/or flight schedules?&lt;/p&gt;&#xA;" OwnerUserId="14125" LastEditorUserId="12720" LastEditDate="2016-03-22T10:19:56.560" LastActivityDate="2016-03-22T10:19:56.560" Title="Is there a standard time zone for flight schedules?" Tags="&lt;flight-schedules&gt;&lt;time&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-03-22T11:15:24.497" ContentLicense="CC BY-SA 3.0" />
  <row Id="26329" PostTypeId="2" ParentId="26318" CreationDate="2016-03-22T06:04:26.727" Score="7" Body="&lt;p&gt;I have flown several times to SJC for touch and goes. I have always been on the weekends, and probably in the afternoons. It is a lot of fun, especially because the runways are so long for a small plane. I think I’ve been three times, and each time they have accommodated me on 30L. The wind is almost always favoring the 30 runways, and I don’t remember ever being cleared for 30R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They will occasionally make you circle briefly before entering the C. They will also sometimes make you extend for a pretty long pattern to the SE if they have a big fella cleared for 30R. All the big commercial jets seem to be sent to 30R, and it is small GA jets that use 30L.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have only done touch and goes, as I wanted to get out of the way quickly. But I get the impression that the tower is happy to accommodate as long as they’re not too busy. My instructor told me that they sometimes will say ‘no’ if they are busy, especially during the morning push, but I have no experience of that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Have fun! There’s a beautiful 787 that is often at the terminal, keep an eye out for it!&lt;/p&gt;&#xA;" OwnerUserId="639" LastActivityDate="2016-03-22T06:04:26.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26330" PostTypeId="2" ParentId="26328" CreationDate="2016-03-22T06:17:50.903" Score="10" Body="&lt;p&gt;Customer facing documents like boarding passes and itineraries typically show local times for ease of use.  Just use airport clocks.  I would not trust the flying public to compute UTC.  It would be chaos.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Crew facing documents will usually be set to UTC, or zulu time.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-03-22T06:24:10.497" LastActivityDate="2016-03-22T06:24:10.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26331" PostTypeId="2" ParentId="26309" CreationDate="2016-03-22T07:07:02.153" Score="1" Body="&lt;p&gt;Most of questions deal with the gravity reduction due increased distance to the Earth but there is also centrifugal force caused by movement. This force allows spaceships to circle the Earth with no power applied and causes weightlessness inside - just increased distance would not be enough for these effects. An airplane is also flying around the Earth, same as a satellite does, just much slower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This effect described &lt;a href=&quot;http://www.phy6.org/stargaze/Srotfram1.htm&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and may reduce the perceived weight (the aircraft feels lighter and everything inside is lighter) but can also increase it (depending on how the flight direction is related to the rotation of the Earth). The effect is somewhat about 0.3 % of mass at the speeds close to the speed of sound so comparable to the effect from the increased altitude.&lt;/p&gt;&#xA;" OwnerUserId="917" LastActivityDate="2016-03-22T07:07:02.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26333" PostTypeId="1" AcceptedAnswerId="26334" CreationDate="2016-03-22T09:07:50.733" Score="5" ViewCount="1426" Body="&lt;p&gt;&lt;em&gt;very similar to &lt;a href=&quot;https://aviation.stackexchange.com/questions/7599/what-happens-to-incoming-flights-when-the-airport-shuts-down&quot;&gt;What happens to incoming flights when the airport shuts down&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event that an airport &lt;a href=&quot;http://www.cbsnews.com/news/reported-explosions-at-brussels-airport-in-belgium&quot; rel=&quot;nofollow noreferrer&quot;&gt;shuts down&lt;/a&gt; for undetermined period, flights that already airborne would be divert to other nearby airports. What about planes those are still on the ground? Would they proceed to takeoff to land at a diversion or would they simply cancel the flights?&#xA;What about next day if the destination airport still close? Would they cancel all flights until airport reopen?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-22T09:25:31.940" Title="What happen to schedule flight when airport close for undertermined duration?" Tags="&lt;airline-operations&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26334" PostTypeId="2" ParentId="26333" CreationDate="2016-03-22T09:25:31.940" Score="6" Body="&lt;p&gt;If an airport is shut down, all flight operations are ceased, with maybe the exception to police, state or medical flights. Scheduled, non-scheduled and general aviation flights will be grounded until the airport is reopened. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flights will be cancelled or the passengers will be bused to airports in the vicinity, from where flights are able to depart, e.g. passengers that were scheduled to depart from &lt;a href=&quot;https://skyvector.com/airport/EDLW&quot; rel=&quot;noreferrer&quot;&gt;Dortmund Airport&lt;/a&gt; would be bused to &lt;a href=&quot;https://skyvector.com/airport/EDLP/Paderborn-Lippstad-Airport&quot; rel=&quot;noreferrer&quot;&gt;Paderborn Airport&lt;/a&gt;. But since the reason for a shutdown usually involves public safety, passengers will be rather evacuated and the flights cancelled, rather then moving them to another airport.&lt;/p&gt;&#xA;" OwnerUserId="572" LastActivityDate="2016-03-22T09:25:31.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26335" PostTypeId="2" ParentId="26223" CreationDate="2016-03-22T10:10:50.703" Score="13" Body="&lt;p&gt;There is a numerical study on the topic at &lt;a href=&quot;http://www.vtnews.vt.edu/articles/2015/10/102815-engineering-jetenginedronestrike.html&quot; rel=&quot;noreferrer&quot;&gt;VirginiaTech&lt;/a&gt;, where they simulated a 5kg drone being ingested by a turbofan, some pictures related to the study below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/k6e5m.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k6e5m.jpg&quot; alt=&quot;From Aerospace America November 2015, graphic Modeling by PhD Students Yangkun Song and Kevin Schroeder of VirginiaTech Crashworthiness for Aerospace Structures and Hybrids lab.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the same  &lt;a href=&quot;http://www.aerospaceamerica.org/Documents/Aerospace%20America%20PDFs%202015/November2015/AA_Nov2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;Aerospace America Article&lt;/a&gt; it can be read that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FAA will begin testing of drone ingestion &lt;a href=&quot;http://www.nbcnews.com/tech/tech-news/engine-makers-havent-tested-drones-n408711&quot; rel=&quot;noreferrer&quot;&gt;next year&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;The metric for danger is the density of the material, so metallic parts are more critical than the bird bones/tissues. Modern drones have more aluminum parts, but the most critical component of a Drone ingestion would be the batteries.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Comparing different sizes, a commercial quad copter is around 1.4kg, while the most frequent bird impact (from &lt;a href=&quot;http://www.faa.gov/airports/airport_safety/wildlife/&quot; rel=&quot;noreferrer&quot;&gt;FAA database&lt;/a&gt;) is around 1.8kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not the worst case scenario since larger drones are commercially available, and a goose, which can weight up to 6kg.&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="5517" LastEditDate="2016-03-22T12:30:47.250" LastActivityDate="2016-03-22T12:30:47.250" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26336" PostTypeId="2" ParentId="26327" CreationDate="2016-03-22T10:49:50.293" Score="2" Body="&lt;p&gt;I would model the energy flows between kinetic and potential energy. Start with a full bucket of potential energy plus the appropriate speed and drain kinetic energy away over time depending on flight speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To know how much energy is lost to drag, you need to &lt;a href=&quot;https://aviation.stackexchange.com/questions/3610/how-are-the-glide-polar-and-l-d-ratio-charts-related/3624?s=3%7C0.1061#3624&quot;&gt;model the drag&lt;/a&gt; using two components:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16953/how-do-insects-decrease-aircraft-performance/16956#16956&quot;&gt;Friction drag&lt;/a&gt;, which grows with the square of airspeed, and&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/24494/induced-drag-of-the-elliptical-wing/24506?s=1%7C0.2246#24506&quot;&gt;Induced drag&lt;/a&gt;, which drops with the square of airspeed.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If your drag is the sum of both, its minimum will be at some moderate speed. I plotted the drag components for a glider below, but since the physics are the same for a paper airplane, this plot should do for now.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/IqqyP.png&quot; alt=&quot;Glider drag components&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nonlinear behavior of the induced drag curve at low speed is due to flow separation, and something very similar will happen for a paper airplane. The important thing is: The drag curve has a minimum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The energy loss over time is drag $D$ times speed $v$. This energy $E$ has to come from the reduction of height $h$ over time $t$:&#xA;$$\frac{\delta E}{\delta t} = \frac{\delta(m\cdot g\cdot h)}{\delta t} = D\cdot v = m\cdot g\cdot v_z$$&#xA;with $m$ the mass of the paper airplane, $g$ gravitational acceleration and $h$ its height above ground. Only $h$ changes over time, so derivation is easy and the derivative of $h$ is $v_z$, the vertical speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For picking a realistic drag it helps to rephrase the equation above by introducing lift $L = m\cdot g\cdot n_z$. $n_z$ is the load factor and is approximately one in straight flight. The ratio between lift and drag for a paper airplane is somewhere between 4 and 10 - just pick a number which results in a realistic simulation. To calculate the sink speed $v_z$ as a function of flight speed $v$ use this formula:&#xA;$$v_z = \frac{c_{D0}\cdot S\cdot v^3\cdot\rho}{m\cdot g\cdot 2} + \frac{m\cdot g\cdot 2}{v\cdot\pi\cdot b^2\cdot\rho}$$&#xA;S is the wing area of the paper airplane and $b$ its wing span. $\rho$ is air density, and for the zero-lift drag coefficient $c_{D0}$ you should pick a number which makes the paper airplane look realistic. Start maybe with 0.05.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-03-22T15:37:21.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26337" PostTypeId="1" CreationDate="2016-03-22T11:38:51.353" Score="3" ViewCount="306" Body="&lt;p&gt;From the &lt;a href=&quot;https://en.wikipedia.org/wiki/Swiss_International_Airlines_Flight_850&quot; rel=&quot;nofollow&quot;&gt;Wikipedia page&lt;/a&gt; on the Swiss International Airlines Flight 850 crash investigation, it was stated that the initial METAR did not reflect the situation and the METAR less than an hour (a moment before the approach was started) was drastically different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Initial METAR:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EDDT 04001KT CAVOK 30/17 Q1002 A2959 0998 2947 NOSIG. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Later:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;EDDT VRB01KT 9999 FEW040CB SCT120 BKN260 29/17 Q1002 A2959 0998 2947 TEMPO 27025G55KT 2000 +TSRA BKN009 BKN015CB COMMENTS: OCNL LTNG AND CB SW OF STN.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not very familiar with these reports, or how they are generated. From some research it sounds like the second report is much more serious, however I'm having trouble understanding a few things:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VRB01KT&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This seems to suggest variable visible range, but I'm not sure what the 01KT means. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Can someone clarify?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The later report first mentions scattered cumulonimbus clouds, but then says the coverage is up to broken. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Why are there multiple mentions of the same types of clouds? &lt;/li&gt;&#xA;&lt;li&gt;Are they talking about different height/direction?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia article seems to suggest that there was a massive storm moving rapidly into the area. My understanding is that NOSIG means the weather is not expected to significantly change in the next two hours. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What would cause the initial report to include NOSIG?&lt;/li&gt;&#xA;&lt;li&gt;Given how much worse the weather seems to be in the later report, why would it take the station almost an hour to file a new report? &lt;/li&gt;&#xA;&lt;li&gt;Why wouldn't they file a new report as soon as it seemed like the weather was degrading?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14128" LastEditorUserId="19" LastEditDate="2016-07-15T07:12:35.947" LastActivityDate="2016-07-15T07:12:35.947" Title="How should the Swiss international airlines flight 850 METAR reports be interpreted?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26339" PostTypeId="2" ParentId="26337" CreationDate="2016-03-22T12:39:47.200" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Can someone clarify?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I can try to clarify the METAR report:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Wikipedia source link on METAR:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;EDDT:  METAR for Tegel Airport&lt;/li&gt;&#xA;&lt;li&gt;VRB01KT: Wind variable at 1 knot (1.9 km/h)&lt;/li&gt;&#xA;&lt;li&gt;9999: visibility in excess of 10 kilometres (5.4 nmi)&lt;/li&gt;&#xA;&lt;li&gt;FEW040CB: few clouds at 4000 ft. including cumulonimbus&lt;/li&gt;&#xA;&lt;li&gt;SCT120:  scattered clouds at 12000 ft&lt;/li&gt;&#xA;&lt;li&gt;BKN260:  broken clouds at 26000 ft &lt;/li&gt;&#xA;&lt;li&gt;29/17: temperature 29 degrees Celsius, dew point 17 degrees Celsius&lt;/li&gt;&#xA;&lt;li&gt;Q1002: current altimeter setting (in QNH) is 1002 hPa &lt;/li&gt;&#xA;&lt;li&gt;A2959 0998 2947: current altimeter setting 29.59 in.Hg, falling to 998 HPa, 29.47 in.Hg. &lt;/li&gt;&#xA;&lt;li&gt;TEMPO: Temporarily&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;27025G55KT: Temporarily winds from 270° at 25 knots (46 km/h), gusting to 55 knots (102 km/h)&lt;/li&gt;&#xA;&lt;li&gt;2000 +TSRA: visibility 2000 meters (1.1 nmi)&lt;/li&gt;&#xA;&lt;li&gt;+TSRA: heavy thunderstorm and rain&lt;/li&gt;&#xA;&lt;li&gt;BKN009: broken clouds at 900 ft&lt;/li&gt;&#xA;&lt;li&gt;BKN015CB: broken clouds at 1500 ft including cumulonimbus&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;COMMENTS: OCNL LTNG AND CB SW OF STN: Occasional lightning and cumulonimbus clouds south west of the station&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Why are there multiple mentions of the same types of clouds? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are they talking about different height/direction?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Sky Condition (i.e.:FEW040CB SCT120 BKN260 ) reports the sky coverage and is given for different &lt;strong&gt;height&lt;/strong&gt;, the following three-digit height is given in hundreds of feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For further clarification of METAR convention I find &lt;a href=&quot;https://aviationweather.gov/static/help/taf-decode.php&quot; rel=&quot;nofollow&quot;&gt;this&lt;/a&gt; useful!&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;My understanding is that NOSIG means the weather is not expected to significantly change in the next two hours. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Correct, &lt;em&gt;NOSIG&lt;/em&gt; stands for NO SIGnificant change, doesn't mean that the weather will not change!&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="609" LastEditDate="2016-03-22T14:38:13.303" LastActivityDate="2016-03-22T14:38:13.303" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26342" PostTypeId="1" AcceptedAnswerId="26343" CreationDate="2016-03-22T15:24:21.043" Score="4" ViewCount="427" Body="&lt;p&gt;I trying to find a way to stay in a jet stream unpowered for a &lt;a href=&quot;https://aviation.stackexchange.com/questions/24420/can-a-football-field-sized-kite-with-a-crew-of-5-like-captain-hooks-crew-in-pet&quot;&gt;larger question&lt;/a&gt;. Is there a glider, kite or plane that flies best when in turbulent weather?&lt;/p&gt;&#xA;" OwnerDisplayName="user20435" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-03-28T06:24:23.253" Title="What flies better in turbulent wind?" Tags="&lt;glider&gt;&lt;turbulence&gt;&lt;ultralight&gt;&lt;hang-glider&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26343" PostTypeId="2" ParentId="26342" CreationDate="2016-03-22T15:50:46.043" Score="5" Body="&lt;p&gt;Turbulence is always a nuisance. It will require more control inputs to stay at the desired polar point, which increases drag. Also, small-scale turbulence will cause earlier transition of the boundary layer, which is important for gliders with a laminar airfoil. Powerful turbulence might even overload the airplane's structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jet stream turbulence is low and only becomes noticeable at the boundaries between the fast moving air of the jet stream and calmer air above and below. To stay unpowered in the jet stream is impossible - any unpowered craft will lose altitude due to drag when moving through the air, and even a balloon will be hard to stabilize at the altitude of highest wind speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even a kite is not unpowered - it needs some force acting on the line; either by an airplane flying below or by something holding the end of the line on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know what makes turbulence more bearable: Higher wing loading, lower aspect ratio and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1726/why-do-some-military-aircraft-use-variable-sweep-wings/3699#3699&quot;&gt;wing sweep&lt;/a&gt; will help. A higher wing loading means higher airspeed, so the relative speed changes from turbulence will become smaller. Both aspect ratio and sweep will reduce the lift curve slope, so changes in angle of attack will result in smaller force changes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-03-28T06:24:23.253" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26344" PostTypeId="2" ParentId="8665" CreationDate="2016-03-22T16:16:38.930" Score="1" Body="&lt;p&gt;The B-52 is still in service due to its high degree of effectiveness. It is not the only plane still in service by means of effectiveness. Other aircraft, such as the F/A-18 Hornet/Superhornet, F-16, F-15, E-2C, C-2, C-130, and UH-1 are still in service because they are still very effective and it would be cost ineffective to replace them. It was anticipated that the F-35 would replace the F/A-18, but after the 3 trillion dollar price tag for the program, and the fact that in test runs against F/A-18 Superhornets and E/A-18G Growlers the F-35 was greatly outperformed, the Department of the Navy decided they will not replace it until around 2035. The B-52 is still very effective for bringing heavy tonnage of explosive ordinance and forcing the hostile force into surrender. If it isn't broken, don't fix it.&lt;/p&gt;&#xA;" OwnerUserId="14135" LastActivityDate="2016-03-22T16:16:38.930" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26345" PostTypeId="2" ParentId="26283" CreationDate="2016-03-22T16:16:49.303" Score="6" Body="&lt;p&gt;The System you are referring to is described in ATA chapter 21. I will report here an example for &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/A320-Air_Conditioning_and_Pressurization.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;A320&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An overview of the system is reported below (from the ATA21 report):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XXg9e.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XXg9e.png&quot; alt=&quot;The schematic of an A320 pressurization system&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the source of pressure reference?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In flight the outside pressure signal can be come from either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The Air Data Reference System (ADIRS), for the pressure altitude.&lt;/li&gt;&#xA;&lt;li&gt;The Flight Management and Guidance Computer (FMGC), for the landing elevation.&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If FMGC not available, uses the landing elevation from the ADIRS and the landing elevation&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How the different valves (outflow, relief) and the packs are related to the CPC?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are two independent safety valves controlled by two independent Cabin Pressure Controllers (CPC) and actuated by three independent motors.&#xA; The pressure in the cabin is controlled only with these valves, while the temperature of the cabin is controlled by mixing the air from the packs with the one of the cabin. In particular the valves are opened and closed to keep the desired pressure profile according to the logic dictated by the different flight phase. &lt;a href=&quot;https://i.stack.imgur.com/jmSGc.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jmSGc.png&quot; alt=&quot;Pressurization Profile&quot;&gt;&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Different constraint drive the controller:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cabin pressure at cruise altitudes is limited to an equivalent &lt;a href=&quot;https://en.m.wikipedia.org/wiki/International_Standard_Atmosphere?wprov=sfla1&quot; rel=&quot;nofollow noreferrer&quot;&gt;ISA&lt;/a&gt; pressure of 8000ft, due to structural fuselage requirements. By providing higher pressures levels (equivalent to lower ISA equivalent altitudes, e.g.: sea level) the fuselage would overstrain. A (very) simplified example  of this is a &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;source=web&amp;amp;rct=j&amp;amp;url=%23&amp;amp;ved=2ahUKEwjKw5-WmKPmAhVFKlAKHV5VBrEQwqsBMAp6BAgHEAQ&amp;amp;usg=AOvVaw0VTJzWxrN8ZFOD4xbU2nov&amp;amp;cshid=1575709768875&quot; rel=&quot;nofollow noreferrer&quot;&gt;balloon in a vacuum chamber&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Maximum descent rate is kept under 750 ft/min for passenger comfort. Otherwise your internal ear starts hurting.&lt;/li&gt;&#xA;&lt;li&gt;At take-off on ground the cabin is de-pressurized till -0.1 psi with a max rate of 400ft/min to avoid pressure surge at rotation&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When and how is used the manual control of the pressure?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Manual control of the pressure is used when both the CBC controllers fail or when the crew uses the cabin press control panel, that you showed. In case of aircraft ditching the inlets are closed as well with a ditching button (first image, right in the CABIN PRESS panel)&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2019-12-07T09:10:46.873" LastActivityDate="2019-12-07T09:10:46.873" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26346" PostTypeId="1" AcceptedAnswerId="26347" CreationDate="2016-03-22T17:30:10.423" Score="13" ViewCount="3379" Body="&lt;p&gt;An &lt;a href=&quot;https://aviation.stackexchange.com/questions/14829/which-airplane-designs-have-the-greatest-longevity&quot;&gt;earlier question&lt;/a&gt; received interesting answers on what airplanes have been in service the longest; this question asks about airplanes &lt;strong&gt;&lt;em&gt;in production&lt;/em&gt;&lt;/strong&gt; the longest.  By this, I mean from earliest production of the first variant, to the end of the production run of the latest variant.  Thus, the 737 would count from 1967 through the present, even though there have been plenty of variants along the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding breaks in production... &lt;strong&gt;&lt;em&gt;EDIT:&lt;/em&gt;&lt;/strong&gt; any break in production less than a decade, doesn't rule out an aircraft.  Multiple breaks in production that total less than a decade of &quot;down&quot; time don't either. An aircraft that is essentially the same produced by somebody else is fine if both are generally regarded as being the same aircraft, even if the designation is different (i.e. the F4U was built by multiple manufacturers, but today everybody thinks of any of them as a Corsair).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military, civilian, large &amp;amp; small, even including gliders &amp;amp; helos (if any have been in production long enough to be competitive) are all fair game.  We can mention balloons (as &quot;aircraft,&quot; though not really &quot;airplanes&quot;) as having been produced since before the Wright brothers, but that's not &lt;strong&gt;&lt;em&gt;really&lt;/em&gt;&lt;/strong&gt; what I have in mind here.  Edit: Nor is &quot;oldest aircraft still in production,&quot; even though the answers tend to be similar since it looks like the aircraft mentioned there are still in production.  This question is about length of production run, even if it is complete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, longest production run... what do we have?&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-03-23T14:20:17.613" Title="Which airplane has had the longest production run?" Tags="&lt;aviation-history&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26347" PostTypeId="2" ParentId="26346" CreationDate="2016-03-22T17:39:17.347" Score="20" Body="&lt;p&gt;Probably the longest production run of any given craft is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Taylor_Cub&quot; rel=&quot;noreferrer&quot;&gt;Taylor Cub&lt;/a&gt; (more popularly known as the Piper Cub).  Which has, in one form or another, been built since about 1930, moving from manufacturer to manufacturer as the years go by.  There's been a recent resurgence in new manufacturers picking up the design lately because it now can be used in the LSA class of aircraft, created a few years back to encourage manufacturers to produce cheap, easy to fly, short range aircraft for recreational purposes.  &lt;a href=&quot;http://www.cubcrafters.com&quot; rel=&quot;noreferrer&quot;&gt;CubCrafters&lt;/a&gt; is one such manufacturer, and here is their, very current, CarbonCub SS as an example of the type:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bwdJP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bwdJP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/2/25/CC11-160_Carbon_Cub.JPG&quot; rel=&quot;noreferrer&quot;&gt;https://upload.wikimedia.org/wikipedia/commons/2/25/CC11-160_Carbon_Cub.JPG&lt;/a&gt;, Author: FlugKerl2&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longest production run for an aircraft from a single manufacturer is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_Bonanza&quot; rel=&quot;noreferrer&quot;&gt;BeechCraft Bonanza&lt;/a&gt; (&lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_most-produced_aircraft&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).  Which has been in continuous production since 1947:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/utPF8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/utPF8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://i.stack.imgur.com/utPF8.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://i.stack.imgur.com/utPF8.jpg&lt;/a&gt;, Author: Bill Larkins&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another long production run is that of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-2&quot; rel=&quot;noreferrer&quot;&gt;Antonov An-2&lt;/a&gt; which also started in 1947 and only ceased in 2001, though a variant, a turboprop version called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-3&quot; rel=&quot;noreferrer&quot;&gt;An-3&lt;/a&gt;, is still in production to this day:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YDvgG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YDvgG.jpg&quot; alt=&quot;Antonov An-2&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://i.stack.imgur.com/YDvgG.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://i.stack.imgur.com/YDvgG.jpg&lt;/a&gt;, Author: Sergey Ryabtsev&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other honerable mentions include the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_C-130_Hercules&quot; rel=&quot;noreferrer&quot;&gt;C-130 Hercules&lt;/a&gt; (in continuous production since 1954, even though only 2300 have been built).  And also, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot; rel=&quot;noreferrer&quot;&gt;Cessna 172&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_182&quot; rel=&quot;noreferrer&quot;&gt;Cessna 182&lt;/a&gt;.  Both started in 1956 and are still going strong today, with older airframes still being extremely common.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it is probably worth pointing out the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_UH-1_Iroquois&quot; rel=&quot;noreferrer&quot;&gt;Uh-1 &quot;Huey&quot; Iroquois&lt;/a&gt;, which has been in production since 1959, and is probably the longest production run for a rotary wing aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jWVEg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jWVEg.jpg&quot; alt=&quot;The UH-1 &amp;quot;Huey&amp;quot; as used by New Zealand&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://i.stack.imgur.com/jWVEg.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://i.stack.imgur.com/jWVEg.jpg&lt;/a&gt;, Author: 111 Emergency&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-03-23T14:20:17.613" LastActivityDate="2016-03-23T14:20:17.613" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26348" PostTypeId="2" ParentId="26309" CreationDate="2016-03-22T18:40:55.470" Score="2" Body="&lt;p&gt;&lt;strong&gt;Gravity decreases with altitude&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.engineeringtoolbox.com/standard-atmosphere-d_604.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this table&lt;/a&gt; providing gravity at different altitudes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/W0YP2.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/W0YP2.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Gravity field at different altitudes (source: &lt;a href=&quot;http://www.engineeringtoolbox.com/standard-atmosphere-d_604.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Engineering Toolbox&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a height of 10 km, gravity is 9.776 against 9.807 at sea level. That's a variation of 0.32%, which I consider as significant from an aircraft design angle, as it allows to reduce the fuel consumption in a larger proportion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Can we sense the gravity difference at the altitude of 10 km?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such difference cannot be sensed by a human, a metering instrument is required. Sensing 0.3% difference just requires a scale. If you &quot;weight&quot; a mass of 100 kg, then at a height of 10 km, the scale will just display 99.7 kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: A gravity value of 9.78 m/s² already exists on Earth, e.g. in Mexico city and in Singapore, due to &lt;a href=&quot;http://units.wikia.com/wiki/Gravity_of_Earth&quot; rel=&quot;nofollow noreferrer&quot;&gt;gravity anomalies&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How fast gravity decreases?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The center of the gravity field is near the center of the Earth. The surface of the Earth is at 6,400 km from the center and the value of gravity is 9.81 m/s² or g.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each time the distance from the center doubles, the gravity value is divided by 4: At 12,800 km, the value is 1/4 g. This progression is said to be an &lt;em&gt;inverse square law&lt;/em&gt;, which looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uZwn0.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uZwn0.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Curve of an inverse square law (&lt;a href=&quot;http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/invsqs.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many physical quantities are based on this same law (light intensity, sound intensity, radio signal intensity). As you can see after 3 or 4 Earth radius, the variation has slowed down a lot, but it continue to decrease and will never reach zero. it means &lt;em&gt;any&lt;/em&gt; object in the universe has an impact on &lt;em&gt;all other&lt;/em&gt; objects! (but a small one).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gravity value decreases when climbing, but also decreases when going underground. Near the center of the Earth the gravity is null (at least that's what we believe, we are not going to be able to check until a very long time, it's easier to explore space than the depths of our planet). This is the complete picture of the gravity: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QzqEi.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QzqEi.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Gravity field according to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Preliminary_reference_Earth_model&quot; rel=&quot;nofollow noreferrer&quot;&gt;preliminary reference Earth model&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gravity is a puzzling force not yet understood. We know local effects of the gravity, but we ignore the reasons of such effects.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-23T14:17:18.770" LastActivityDate="2016-03-23T14:17:18.770" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26349" PostTypeId="1" CreationDate="2016-03-22T19:55:17.790" Score="1" ViewCount="411" Body="&lt;p&gt;I'm designing an aircraft for fun, and I've selected a CFE738-1-1B as the engine. It's never going to fly outside of X Plane, but it's still fun, so I'd like to make the X Plane version as realistic as possible. This means that I need to know a bit about this engine (it's used in the Falcon 2000, so any Falcon 2000 pilots, not including anything after the 2000 like 2000EX, you would be very helpful). What I need to know and haven't been able to find on the internet is the following:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Minimum N2 to avoid a hot start.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Length of time it takes from beginning of engine start to idle fuel flow.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Time from idle throttle to max throttle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Time for N1 to spool up to max from idle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Thrust curves.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;SFC at half thrust at 0 and 40,000 feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel flow at flight idle.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Any help much appreciated (Don't feel obligated to answer all of these in the same post)!&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="12220" LastEditDate="2016-03-22T20:25:52.577" LastActivityDate="2016-03-22T20:25:52.577" Title="What are the specifications for the CFE738-1-1B?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="0" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26351" PostTypeId="1" CreationDate="2016-03-23T00:33:35.153" Score="11" ViewCount="2392" Body="&lt;p&gt;I was studying for icing and a tailplane stall. I have looked up some internet pages and instrument flying handbook, and found the procedure below.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;raise flaps to the previous setting. (To reduce down wash from the main wing so that reducing negative angle of attack of the tail and break the stall)  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;apply nose up elevator pressure (I don't get it. The nose up pressure will make the elevator to go up and wouldn't this increase the negative angle of attack and worsen the stall?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;do not increase airspeed unless it is necessary to avoid a wing stall. (Why shouldn't we increase airspeed?)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;So now I'm trying to understand the reason why should a pilot do such actions. Can you help me out?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="4197" LastEditDate="2016-03-23T08:40:23.833" LastActivityDate="2019-04-14T22:54:35.907" Title="How can we recover from a tailplane stall?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26352" PostTypeId="1" CreationDate="2016-03-23T04:32:36.013" Score="10" ViewCount="816" Body="&lt;p&gt;That is certainly a beginner question but I cannot find the answer anywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia page on &lt;a href=&quot;https://en.wikipedia.org/wiki/Geodesic&quot; rel=&quot;nofollow noreferrer&quot;&gt;geodesics&lt;/a&gt; says that they are the shortest path between two points on a geometric object (surface, manifold,...). It also  mentions geodesic airframes as a real-life application. However, the linked page about &lt;a href=&quot;https://en.wikipedia.org/wiki/Geodetic_airframe&quot; rel=&quot;nofollow noreferrer&quot;&gt;geodesic airframes&lt;/a&gt; does not seem to deal with geodesic curves. It is mostly about about a structure made by triangles or other polygons. A &lt;a href=&quot;https://aviation.stackexchange.com/questions/12277/why-are-geodesic-airframes-no-longer-produced&quot;&gt;related question&lt;/a&gt; explaining why geodesic frames are no longer in use is answered only with this point of view.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, my question: are geodesic frames related to geodesic curves? If yes, in what way?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My intuition is that geodesic curves are used to design the shape of the &quot;perfect&quot; frame (with respect to some constraints), and that the polygonal structure is an approximation of this perfect shape.&lt;/p&gt;&#xA;" OwnerUserId="14142" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-25T15:04:18.037" Title="What is the relation between geodesic airframe and geodesic curves?" Tags="&lt;aircraft-design&gt;&lt;airframe&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26353" PostTypeId="1" CreationDate="2016-03-23T09:19:26.553" Score="9" ViewCount="6121" Body="&lt;p&gt;Elon Musk has said that he has a design for a vertical take off and landing super sonic electric jet. I was under the impression that jet engines work by burning fuel, expanding volume and thus creating force. How can this be done electrically?&lt;/p&gt;&#xA;" OwnerUserId="14105" LastEditorUserId="5517" LastEditDate="2016-03-25T15:45:34.817" LastActivityDate="2017-08-06T17:26:32.187" Title="What does Elon Musk mean by &quot;electric jet&quot;?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;electric-engine&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26354" PostTypeId="1" AcceptedAnswerId="26358" CreationDate="2016-03-23T09:30:27.667" Score="7" ViewCount="2496" Body="&lt;p&gt;I've read phrases like &quot;All gas turbine engines use pressurized seals for their shaft bearing compartments to keep [...]&quot; but I do not understand what &quot;seals&quot; means. In spanish we haven't a word for it.&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="1467" LastEditDate="2016-03-23T09:51:34.470" LastActivityDate="2020-01-16T15:35:30.407" Title="What is a seal in aeronautics?" Tags="&lt;terminology&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26355" PostTypeId="2" ParentId="26354" CreationDate="2016-03-23T09:45:07.797" Score="8" Body="&lt;p&gt;Seals are things like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jwVAG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jwVAG.jpg&quot; alt=&quot;Pressurised shaft seal&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;they prevent oils and other fluid from contaminating areas where they do not belong (and they prevent impurities from contaminating the oils).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see one of these used in this assembly diagram (the &quot;oil seal&quot;) to protect the ball bearing assembly:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mJ9xR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mJ9xR.jpg&quot; alt=&quot;Shaft assembly diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(Image &lt;a href=&quot;http://automotiverepairguides.blogspot.de/2013/07/fiat-131-1975-77-drive-axles-repair.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-03-23T11:49:54.900" LastActivityDate="2016-03-23T11:49:54.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26356" PostTypeId="2" ParentId="26354" CreationDate="2016-03-23T09:45:44.860" Score="8" Body="&lt;p&gt;&quot;Seal&quot; is used here to mean &quot;&lt;a href=&quot;http://www.wordreference.com/es/translation.asp?tranword=seal&quot;&gt;closure&lt;/a&gt;&quot;. Specifically, a seal is a mechanism which prevents gases (or liquids) from crossing a barrier.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, a rotating shaft must be connected to a fixed structure by means of a bearing (which allows it to rotate). If dirt or liquid were to enter the bearings, it would damage the mechanisms inside. Therefore, seals are used to keep dirt and liquids out of the bearings. Here is an example from general machinery: &lt;a href=&quot;http://www.machinerylubrication.com/Read/838/protect-bearings&quot;&gt;http://www.machinerylubrication.com/Read/838/protect-bearings&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="1478" LastActivityDate="2016-03-23T09:45:44.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26357" PostTypeId="2" ParentId="26351" CreationDate="2016-03-23T12:06:03.493" Score="5" Body="&lt;p&gt;Lets start with the very basic concepts....&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In most aircraft, the Centre of Gravity (cg) is somewhat forward of the wing or mainplane Centre of Pressure. The exact distance between the cg and the Centre of pressure will depend on aircraft loading, configuration, thrust setting and drag. However, cg forward of the Centre of Pressure produces a nose-down pitching moment. The horizontal stabilizer, or tailplane, then provides a downward force to overcome this normal, nose-down, pitching moment.&#xA;The tailplane behaves as an ‘upside down’ wing and operates with negative Angle of Attack (AOA) as shown in Figure 1&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Positive and Negative Angle of Attack&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/60asc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure 1 - Positive and Negative Angle of Attack&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the horizontal stabiliser becomes contaminated with ice, airflow separation from the surface can prevent it from providing sufficient downward force or negative lift to balance the aircraft and a nose-down pitch upset can occur.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When compared to an aircraft's mainplane, the horizontal stabiliser normally has a thinner aerofoil with a sharper leading edge. Differences in the ice collection efficiency or catch rate between the two surfaces means ice accumulates faster on the horizontal stabiliser and may form before any ice is present on the aircraft's mainplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tailplane stall can occur at relatively high speeds, well above the normal 1G stall speed of the mainplane. Typically, tailplane stall induced by icing is most likely to occur near the flap limit speed when the flaps are extended to the landing position, especially when extension is combined with a nose down pitching manoeuvre, airspeed change, power change or flight through turbulence. Aircraft stall warning systems provide warnings based on an uncontaminated mainplane stall so during a tailplane stall induced upset there will be NO artificial stall warning indications, such as a stick shaker, warning horn or the mainplane or flap buffeting normally associated with a mainplane stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tailplane Stall Aerodynamics&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The horizontal stabiliser, or tailplane, of an aircraft is an aerofoil that provides a downward force to overcome the aircraft's normal nose-down pitching moment. The further forward the Centre of Gravity is from the Center of Pressure, the greater the nose down moment and, thus, the greater the amount of down-force that must be generated by the tailplane. This, in turn, requires a greater negative tailplane angle of attack (AOA). angle of attack (AOA).&#xA;[As shown in Figure 1, The tailplane is effectively an upside down aerofoil so an increase in negative tailplane AOA occurs with UP elevator movement or when the aircraft is pitching nose down.]&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Accumulation of ice on the tailplane will result in disruption of the normal airflow around that surface and will reduce the critical (or stalling) negative AOA of the horizontal stabiliser.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ice can accumulate on the tailplane before it begins to accumulate on the mainplane or other parts of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flaps extension usually moves the mainplane Centre of Pressure aft, lengthening the arm between the Centre of Pressure and the cg and increasing the mainplane nose down moment. More down force is required from the tailplane to counter this moment, necessitating a higher negative tailplane AOA.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flap extension, especially near the maximum extension speed, increases the negative tailplane AOA due to the increase in downwash, as shown in Figure 2&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Increasing the power setting on a propeller driven aircraft may, depending on aircraft configuration and flap settings, increase the downwash and negative tailplane AOA.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When the critical negative AOA of the horizontal stabiliser is exceeded causing it to stall.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Tailplane stall drastically reduces the downward force it produces, creating a rapid aircraft nose-down pitching moment.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Effect of mainplane flap on downwash&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/xHo2B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Figure 2 - Effect of mainplane flap on downwash&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On aircraft with reversible (unpowered) elevator, tailplane airflow changes caused by ice accretion may lead to an aerodynamic overbalance driving the elevator trailing edge down and pitching the aircraft nose down. This can occur separately from or in combination with the nose down pitching moment caused by tailplane stall. The yoke may be snatched forward out of the pilot’s hands and the control force required for the pilot to return the elevator to neutral or to a nose-up deflection can be significant and potentially greater than the pilot can exert.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;now match with your recovery actions&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You have no doubt with your 1st point.&lt;/li&gt;&#xA;&lt;li&gt;The second point: You have to resist the nose down elevator movement. Once the tailplane is already stalled then you have to assume the elevator has already gone in down position to make your ac nose down. So you have to apply nose up elevator pressure. &lt;/li&gt;&#xA;&lt;li&gt;You should not increase the airspeed cause it might make the situation worse. Cause in dive with increased airspeed is always difficult to maintain the aircraft control. And you might end up with overstressing the elevator which is not good at all in such condition.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="13956" LastActivityDate="2016-03-23T12:06:03.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26358" PostTypeId="2" ParentId="26354" CreationDate="2016-03-23T12:38:05.573" Score="18" Body="&lt;p&gt;&lt;strong&gt;Translation&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Seal&lt;/em&gt; means &lt;em&gt;&lt;a href=&quot;https://carbosystem.com/sellos-mecanicos/&quot; rel=&quot;nofollow noreferrer&quot;&gt;sello mecánico&lt;/a&gt;&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the answer could stop here, we wouldn't know what seal types are used in turbine engines, and how some are pressurized to prevent &lt;a href=&quot;https://www.faa.gov/data_research/research/med_humanfacs/oamtechreports/2010s/media/201520.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;contaminants&lt;/a&gt; entering the aircraft pressure vessel.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Need for bearing compartments and seals&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I've read phrases like &quot;All gas turbine engines use pressurized seals&#xA;  for their shaft bearing compartments...&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In turbine engines, there are one or more shafts holding the rotating parts of the compressors and turbines (rotors). &lt;a href=&quot;https://www.ntnglobal.com/en/products/review/pdf/NTN_TR82_en_083_087p.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bearings&lt;/a&gt; are inserted between a shaft and its stationary supports to limit destructive and heat-generating friction. Bearings also bear the large &lt;a href=&quot;https://www.flight-mechanic.com/bearings/&quot; rel=&quot;nofollow noreferrer&quot;&gt;axial load&lt;/a&gt; transferred by compressor and turbine rotors to the shafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In turbine engine bearings, solid friction is replaced by fluid friction using an oil film between balls or rollers and races. Bearings are enclosed in a cavity and oil is injected into the cavity. This cavity is known as a &lt;em&gt;sump&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The following drawing is taken from  &lt;a href=&quot;https://aviation.stackexchange.com/questions/25877/in-a-turbofan-what-holds-the-spinning-axis/25879#25879&quot;&gt;an answer to &lt;em&gt;In a turbofan what holds the spinning axis?&lt;/em&gt;&lt;/a&gt;. You can see the five bearings within their sumps:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a1poV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a1poV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.slideshare.net/ccoyure/ata-72-cfm56-3&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oil must be circulated from the oil tank to the sumps and back, and cooled before being reused. As oil quantity is limited, oil must be prevented from leaving the oil system. This is where seals enter into action. In particular, seals are used to prevent leakage between a rotating shaft and stationary sump apertures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;High speed seals&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turbo engines' oil seals are specially selected to bear the high rotation speed of the shafts (wear), and the high operating temperature of the engine core (adjustment and bending). They are of two main types: Carbon or labyrinth. Both reduce oil pressure while it travels in the interstice between the shaft and the sump wall. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DfOvY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DfOvY.jpg&quot; alt=&quot;Carbon and labyrinth seals&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Carbon (&lt;a href=&quot;https://www.aeroexpo.online/prod/skf-aerospace/product-170575-47142.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) and labyrinth (&lt;a href=&quot;https://www.indiamart.com/proddetail/turbine-labyrinth-seal-13540917233.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) seals&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Air sealing&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All gas turbine engines use pressurized seals&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As one would think, these seals are not perfect: a small quantity of oil will be able to make its way across the seal, and this quantity will increase with seal wear. Unfortunately, burnt oil releases hazardous fumes which could enter the aircraft air conditioning system as cabin air is tapped most of the time into the engine compressor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To limit the leakage further and to recover leaked oil, a second cavity is built around the first seal and pressurized air is injected into it. This has two effects:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air pushes oil back into the sump.&lt;/li&gt;&#xA;&lt;li&gt;The second cavity being also sealed, any leaked oil can be drained and dumped overboard.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For example, the forward sump (on the left of the first picture) encloses 3 bearings (from left to right: #1, #2 and #3). Oil must be contained within the sump near bearings #1 and #3. Let's look at a CFM56-7B engine mounted on Boeing 737 NG. This is the lower half of the forward sump:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DSzbZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DSzbZ.png&quot; alt=&quot;CFM56-7B forward sump sealing&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;CFM56-7B forward sump, based on drawing from &lt;a href=&quot;https://www.scribd.com/doc/305212389/Cfm56-7b-Familiarization-Print&quot; rel=&quot;nofollow noreferrer&quot;&gt;CFM56-7B Familiarization Manual&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Oil enters the sump and is directed to bearing races using tubes and oil nozzles.&lt;/li&gt;&#xA;&lt;li&gt;An oil seal prevents oil from escaping the sump in large quantity.&lt;/li&gt;&#xA;&lt;li&gt;As some oil would nevertheless cross the seal, compressed air is injected on the other side of the seal, to counter oil leakage. Air entering the sump is then dumped overboard by the centrifugal air-oil separators.&lt;/li&gt;&#xA;&lt;li&gt;The space where air is injected is closed by a cap on the sump with a air seal on the shaft.&lt;/li&gt;&#xA;&lt;li&gt;Air and a small quantity of oil able to cross the oil seal are eventually drained and released overboard.&lt;/li&gt;&#xA;&lt;li&gt;Oil crossing the bearing is scavenged and returns to the oil tank after air has been removed. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Metal particles in scavenged oil are captured by magnets to detect abnormal wearing of bearings. From time to time &lt;a href=&quot;https://aviation.stackexchange.com/q/46038/3201&quot;&gt;oil is added to the oil tank&lt;/a&gt; to compensate for small leakages in the bearing sumps (and in the gearboxes).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;See on Youtube: &lt;a href=&quot;https://www.youtube.com/watch?v=WQGW-60xxcQ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Carbon Seals - Turbine Engines: A Closer Look&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-01-16T15:35:30.407" LastActivityDate="2020-01-16T15:35:30.407" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26359" PostTypeId="2" ParentId="26351" CreationDate="2016-03-23T13:29:20.180" Score="2" Body="&lt;p&gt;There was a NASA report on the &lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19990019485&amp;amp;hterms=19990019485&amp;amp;qs=Ntk%3DDocument-ID%26Ntt%3D19990019485%26N%3D0&quot; rel=&quot;nofollow noreferrer&quot;&gt;NASA/FAA Tailplane Icing Program Overview&lt;/a&gt;, which covers the points raised by you. It lists certain actions that can be done to recover from a tail plane stall:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the full tail stall was experienced during the power transition, the stall recovery procedure was:&lt;/p&gt;&#xA;&lt;p&gt;• Reduce thrust (may be airplane specific)&lt;/p&gt;&#xA;&lt;p&gt;• Pull back on yoke/ increase &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;p&gt;• Raise flaps&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Raise flaps to previous setting&lt;/p&gt;&#xA;&lt;p&gt;This is done mainly to undo the changes that caused the stall in the first place (reducing thrust is also done for this reason). The report says,&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The major lesson learned to recover from a tail stall was to undo what was&#xA;just done to cause the event.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Apply nose up elevator pressure&lt;/p&gt;&#xA;&lt;p&gt;Basically you are pulling back on the yoke to increase the tail download so that the aircraft nose-down pitching moment is countered. From the report:&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Pulling back on the yoke increased the camber of the tailplane, which provided enough tail download to counteract the nose-down pitching moment and increase the &lt;span class=&quot;math-container&quot;&gt;$\alpha_{tail}$&lt;/span&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This sounds counterintutive as the conventional tail produces force in the direction opposite to the main wing. The report notes:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;It was noted that this tail stall recovery procedure is opposite of the recovery from a wing stall. The reason for the difference is the location of the flow separation. In a wing stall, the flow separates from the upper surface of the wing, therefore reattachment is made by decreasing the wing &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt;. In a tail stall event, the flow separates from the lower surface of the tail and requires a positive increase in tail to reattach the flow.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Do not increase airspeed unless it is necessary to avoid a wing stall&lt;/p&gt;&#xA;&lt;p&gt;The aircraft is already at a nose down attitude. Increasing speed will further excabarate the situation, which may put the corrective action beyond the capability of the tailplane.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-23T13:29:20.180" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26360" PostTypeId="1" AcceptedAnswerId="26363" CreationDate="2016-03-23T14:18:01.367" Score="4" ViewCount="3503" Body="&lt;p&gt;For analysing the FDR, data is downloaded to the local computer from the FDR and feed into the Analysing Software. I would like to know what is the file extension of the data stored on the FDR. &#xA;I came to the conclusion that it must be csv for storing all the data about Height, longitude, latitude and so on. Then this .csv file is feed into the Analysing Software for analysing. But I am not sure if I am correct. &lt;/p&gt;&#xA;" OwnerUserId="14149" LastEditorUserId="14150" LastEditDate="2016-03-23T14:32:53.507" LastActivityDate="2016-03-23T23:32:17.687" Title="What data file format is used by FDRs?" Tags="&lt;flight-data-recorder&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ClosedDate="2016-03-26T06:28:45.473" ContentLicense="CC BY-SA 3.0" />
  <row Id="26361" PostTypeId="1" AcceptedAnswerId="26364" CreationDate="2016-03-23T14:42:08.130" Score="3" ViewCount="2392" Body="&lt;p&gt;When the FAA approves a hardware or software (or mixed) system for use in an aircraft requiring Type Certification, A Designated Engineering Representative (DER) is selected to work with the developers and apply the safety assurance guidelines (or other alternative means of compliance) needed for approval. Although the DER is not the final authority granting approval, &lt;em&gt;de facto&lt;/em&gt; if you fail to satisfy the DER you won't get approval, and if the DER finds that all needed guidelines have been met and all evidence is in order, you probably will.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The EASA process in Europe is very similar, but many of the acronyms and terms they use are different, which brings me to the question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the European (EASA) equivalent of what in America we call the Design Engineering Representative (DER)?&lt;/p&gt;&#xA;" OwnerUserId="12120" LastActivityDate="2016-03-23T15:56:42.857" Title="What term is the EASA equivalent of the DER in the FAA safety assurance process?" Tags="&lt;safety&gt;&lt;terminology&gt;&lt;easa-regulations&gt;&lt;easa&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26363" PostTypeId="2" ParentId="26360" CreationDate="2016-03-23T15:27:13.613" Score="7" Body="&lt;p&gt;The builders of an FDR must comply with &lt;a href=&quot;https://en.wikipedia.org/wiki/DO-178C&quot; rel=&quot;nofollow&quot;&gt;DO-178C&lt;/a&gt; (the older &lt;a href=&quot;https://en.wikipedia.org/wiki/DO-178B&quot; rel=&quot;nofollow&quot;&gt;DO-178B&lt;/a&gt; may also be of interest here) as per &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-141B.pdf&quot; rel=&quot;nofollow&quot;&gt;AC 20-141B issued by the FAA&lt;/a&gt;. These documents do not specifically define a data format but provide requirements for what it must be resilient against. Here is an &lt;a href=&quot;https://people.cs.uchicago.edu/~shanlu/paper/FDR-OSDI-CR-FINAL.pdf&quot; rel=&quot;nofollow&quot;&gt;interesting research paper&lt;/a&gt; that covers some of the topics you are asking about. Since most avionics use &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC_429&quot; rel=&quot;nofollow&quot;&gt;ARNIC 429&lt;/a&gt; as their standard of communication some FDRs provide &lt;a href=&quot;http://www.l-3ar.com/pdf/datasheets/MKT060-AP_DASU_12-12rev3.pdf&quot; rel=&quot;nofollow&quot;&gt;ARNIC 429 inputs&lt;/a&gt; to record the avionics instructions at the time. I would assume these inputs dump the bus data right to the storage medium (most likely solid state memory these days). Since the formats the device uses may be proprietary as well as very low level (and memory efficient) I am sure they make software to dump it to other formats. For example &lt;a href=&quot;http://www.l-3ar.com/pdf/datasheets/MKT064-AP_RAU_12-12rev3.pdf&quot; rel=&quot;nofollow&quot;&gt;L3 makes a full unit for their FDRs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some more searching I found what may be the most comprehensive answer from this &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_02/textonly/s01txt.html&quot; rel=&quot;nofollow&quot;&gt;Boeing summary document&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What Is a Data Frame?&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A flight data recorder (FDR) data frame is the&#xA;  order of the words that are transmitted from the digital flight data&#xA;  acquisition unit (DFDAU) to the digital FDR (DFDR) each second over&#xA;  many seconds (see ARINC 717 for additional information). Most FDR&#xA;  system data frames are made up of four subframes within one&#xA;  superframe. For a 64-words-per-second (wps) FDR system, a DFDAU will&#xA;  output 64 12-bit words to the FDR each second, where each word&#xA;  typically contains the value of an analog parameter. The order of the&#xA;  words (for example, word number 12 of the 64 words) within a subframe,&#xA;  as well as the order of the subframes, define an FDR data frame. This&#xA;  order is important to understand in order to decode the data recorded&#xA;  in the DFDR.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It should also be noted although they may have all been phased out by now, some older cockpit voice recorders and FDRs recorded on analog mediums and may still be inservice doing so.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-23T23:32:17.687" LastActivityDate="2016-03-23T23:32:17.687" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26364" PostTypeId="2" ParentId="26361" CreationDate="2016-03-23T15:56:42.857" Score="0" Body="&lt;p&gt;The closest EASA equivalent would be the Design Organisation Approval (DOA). According to &lt;a href=&quot;https://www.easa.europa.eu/easa-and-you/aircraft-products/design-organisations/design-organisations-approvals&quot; rel=&quot;nofollow noreferrer&quot;&gt;EASA&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A Design Organisation Approval is the recognition that a Design Organisation complies with the requirements of Part 21 Subpart J.&lt;/p&gt;&#xA;&lt;p&gt;Privileges: A DOA holder can&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Perform design activities within the scope of approval&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Have compliance documents accepted by the Agency without further verification&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Perform activities independently from the Agency&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-23T15:56:42.857" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26365" PostTypeId="2" ParentId="26353" CreationDate="2016-03-23T16:18:23.257" Score="7" Body="&lt;p&gt;&lt;strong&gt;Jet&lt;/strong&gt; &lt;em&gt;noun&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a rapid stream of liquid or gas forced out of a small opening&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A Jet Engine is an Engine which uses a Jet for propulsion. Typically, a &quot;rapid stream of gas&quot;, in which the gas is air. Really, we could count pretty much any aircraft engine as a jet, but it depends on how &quot;rapid&quot; you require the air to be before it's a jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a typical jet engine as we define it now, the jet is created by burning fuel and air... but there's no requirement for that to be the case. An electric jet would simply use an electric motor to create a rapid stream of air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would it &lt;strong&gt;really&lt;/strong&gt; be a &quot;jet&quot; engine? That depends how fast the air is - but most people see &quot;jet&quot; as being a fast, powerful, reliable type of aircraft, so it's as much about marketing as anything else. An Electric Prop or Electric Plane doesn't sound as cool as Electric Jet... (Although I'd argue that ElectroJet/ElectroProp/ElectroPlane are awesome names and Elon Musk has let himself down by not using one of those names)&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-03-23T16:18:23.257" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26366" PostTypeId="1" CreationDate="2016-03-23T16:56:56.940" Score="5" ViewCount="859" Body="&lt;p&gt;IN EASA safety approval guidance, particularly &lt;a href=&quot;https://www.easa.europa.eu/system/files/dfu/certification-docs-certification-memorandum-EASA-CM-SWCEH-001-Development-Assurance-of-Airborne-Electronic-Hardware.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;CM – SWCEH – 001&#xA;&lt;em&gt;Development Assurance of Airborne Electronic Hardware&lt;/em&gt;&lt;/a&gt;, the entity charged with making sure that a system meets applicable requirements and guidelines (especially concerning safety) is called &amp;quot;Panel 10.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;However, in section  5.2 &amp;quot;Background&amp;quot; there is a list of panels, and there, Safety is listed as Panel 12.  (Immediately after this list comes most of the assurance-related material, which extensively speaks of Panel 10.)  Yet no other mention of Panel 12 is made in this document.&lt;/p&gt;&#xA;&lt;p&gt;Is this just a typo, where they meant Panel 10, not Panel 12?&lt;/p&gt;&#xA;" OwnerUserId="12120" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-02-26T15:40:36.990" Title="In EASA, what is Panel 12? Is this just the same as Panel 10?" Tags="&lt;safety&gt;&lt;easa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26367" PostTypeId="1" AcceptedAnswerId="26368" CreationDate="2016-03-23T17:21:45.907" Score="20" ViewCount="3623" Body="&lt;p&gt;I'm a physicist who was amused by the argument in the comments of &lt;a href=&quot;https://aviation.stackexchange.com/questions/26309/is-gravity-less-on-an-airliner-at-cruise-altitude&quot;&gt;this question about gravity&lt;/a&gt;.  The correct answer about the affect of the accelerating reference frame of the plane on the apparent gravity depends on how the airliner's speed is measured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know very little about practical aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I'm on a trans-Atlantic flight moving 900 km/hr, with respect to what am I moving?  Is that my speed relative to the ground (which is also moving)? relative to the local atmosphere (which could be additionally moving due to wind)? relative to some imaginary, absolute grid hovering above the Earth's surface? relative to the &quot;fixed stars&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is probably a duplicate, but I can't seem to find the right search terms...&lt;/p&gt;&#xA;" OwnerUserId="14152" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-03-24T16:38:34.010" Title="What is the reference used when measuring flight speed?" Tags="&lt;airspeed&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26368" PostTypeId="2" ParentId="26367" CreationDate="2016-03-23T17:57:20.917" Score="24" Body="&lt;p&gt;Speed of a plane is actually measured in a number of different ways, and relative to different things. Here is a summary of the different types:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Indicated Airspeed&lt;/strong&gt; (IAS). This is the number shown on the instrument that measures airspeed, and isn't really relative to anything.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Rectified Airspeed&lt;/strong&gt; (RAS) or Calibrated Air Speed (CAS) This is IAS corrected for known errors in the instrument and the measurement system.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;True Air Speed&lt;/strong&gt; This is the speed relative to the air around the aircraft; usually found by correcting the RAS for pressure and some other errors.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Ground Speed&lt;/strong&gt; This is the speed relative to the ground, or a fixed point on the earth ('imaginary grid). Its the vector addition of the True Airspeed (and direction) plus the wind speed (and direction). In olden days this was estimated from the Airspeed and the wind velocity, or through dead reckoning navigation, but now it is trivially found from GPS or other navigation aids.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Planes use different ones of these for different purposes. Measurements relative to the fixed stars are not generally useful until you are in the realm of space travel.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2016-03-24T16:05:43.863" LastActivityDate="2016-03-24T16:05:43.863" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26373" PostTypeId="2" ParentId="26360" CreationDate="2016-03-23T21:16:53.347" Score="4" Body="&lt;p&gt;We can use &lt;a href=&quot;https://en.wikipedia.org/wiki/Inductive_reasoning&quot; rel=&quot;nofollow noreferrer&quot;&gt;inductive reasoning&lt;/a&gt; to make a guess at a &lt;strong&gt;probable&lt;/strong&gt; answer to your question.&lt;/p&gt;&#xA;&lt;p&gt;Your premise:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;I came to the conclusion that it must be csv&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;is likely wrong.&lt;/p&gt;&#xA;&lt;p&gt;The only purpose of a CSV file is to transfer data between a source and a sink which do not understand the way in which the other stores data.&lt;/p&gt;&#xA;&lt;p&gt;An FDR does not need to be understood by any other sink other than the manufacturer and/or incident investigators.&lt;/p&gt;&#xA;&lt;p&gt;Adding the ability to store or retrieve data in a CSV format would add some complexity, through additional problems to solve, which is simply not needed.&lt;/p&gt;&#xA;&lt;p&gt;All that is required is a method to extract the raw data and display it in a format that humans can understand.  This is trivially done with a piece of custom software.&lt;/p&gt;&#xA;&lt;p&gt;The designers will have no requirement to provide data in any format other than that required by the extraction software so they simply won't implement it.&lt;/p&gt;&#xA;&lt;p&gt;CSV, and other data interchange format files, all have limitations.  They lose resolution, they are inefficient in their use of resources and only exist to work around problems introduced by a lack of standards, differing interpretations of standards and attempts by commercial, general purpose software vendors to differentiate themselves or make it more difficult for systems to interoperate.&lt;/p&gt;&#xA;&lt;p&gt;We can therefore reasonably conclude that an FDR does not store data in a CSV file.  Of course, the custom software which does extract the data &lt;em&gt;might&lt;/em&gt; contain such a feature but then again, why would it?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-23T21:38:02.443" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26374" PostTypeId="2" ParentId="5070" CreationDate="2016-03-23T22:26:40.517" Score="10" Body="&lt;p&gt;Unlike the AAIB, the NTSB &lt;em&gt;does&lt;/em&gt; release FDR data dumps (adjusted for engineering units and culled to the same parameters as the graphs) as part of the docket release for a given accident -- no FOIA pestering needed!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://dms.ntsb.gov/pubdms/search/document.cfm?docID=424787&amp;amp;docketID=57175&amp;amp;mkey=89324&quot;&gt;these&lt;/a&gt; &lt;a href=&quot;http://dms.ntsb.gov/pubdms/search/document.cfm?docID=424788&amp;amp;docketID=57175&amp;amp;mkey=89324&quot;&gt;examples&lt;/a&gt; from the Bedford, MA Gulfstream overrun crash, for instance (they're CSV files).  You'll be able to find more by looking through the dockets associated with recent major NTSB accident reports.&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2016-03-23T22:26:40.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26375" PostTypeId="2" ParentId="26367" CreationDate="2016-03-23T23:40:54.053" Score="7" Body="&lt;p&gt;There are multiple speeds referred to in aviation, some of which are not 'speed' in the traditional sense.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Indicated airspeed (IAS): This is a measure of dynamic pressure and not actual speed, measured using the pitot-static system (i.e. difference of the total and static pressure). It is a function of density and airspeed, not speed alone. Usually, the critical speeds are given in terms of IAS as the aircraft behaves similarly in same IAS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Calibrated Airpseed (CAS): This is nothing but the Indicated airspeed corrected for instrument and position errors- still not an actual speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;True airspeed: This gives the speed of the aircraft in relation to the sorrounding airmass. This is the speed used in the flight planning (before taking into account wind, that is) and for measuring aircraft performance. This is the speed with respect to the local atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ground speed: This is the speed of the aircraft with respect to the ground and as such akin to the speed of the car. This cannot be measured without an external instrument and usually, measured with GPS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As far as air travel is concerned, speeds relative to stars are not used, as there is no need for such complexity.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-23T23:40:54.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26376" PostTypeId="2" ParentId="26367" CreationDate="2016-03-24T00:17:16.557" Score="1" Body="&lt;p&gt;I will try to add some information to the previous questions, which are correct. My intention is to provide you physical meaning, but previous answers are essentially correct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When discussing reference frames where the speed is usually provided I will essentially summarize in 2:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airplane reference (aka body axis): is the ideal reference frame attached to the airplane (not usually considering acceleration, but in practice should be done). The upstream speed is measure here (as the air approaches the airplane in this reference frame) and has been mentioned before as best approximation as &quot;&lt;strong&gt;True Airspeed&lt;/strong&gt;&quot; (the other are measured and calibrated speeds).&lt;/li&gt;&#xA;&lt;li&gt;Ground reference: is the reference located at the ground, usually located just below the airplane. That's &quot;&lt;strong&gt;Ground Speed&lt;/strong&gt;&quot;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you would like to know further about reference frames in the airplane, there are more reference frames (or variations of the previous one):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Body reference: just intermediate step to define other systems I am coming back to this one. Is located in the center of gravity, the x axis goes along the fuselage from cockpit to tail, z axis along gravity.&lt;/li&gt;&#xA;&lt;li&gt;Stability reference: is the body reference rotated along y axis to make the external air speed component in the z direction 0. It is usually used to define angle of attack and compute stability of the trajectory.&lt;/li&gt;&#xA;&lt;li&gt;Wind reference: is the stability reference rotated along z axis to make the air speed in this reference only in x direction. Formally this is where lift and drag are defined. (Notice that in body reference you are propulsed by aerodynamic force at the vertical tail plane. :)) Also, sideslip is defined as the rotation of axis system.&lt;/li&gt;&#xA;&lt;li&gt;I have seen some literature defining lift and drag in stability reference.&lt;/li&gt;&#xA;&lt;li&gt;I have seen in structural context to define another reference frame, x as in body reference and y axis along the wing as in body reference. This system is different to Body reference when turning, and used to compute the load factor.&lt;/li&gt;&#xA;&lt;li&gt;It is very common to assume that the airplane is quasi-stationary, so no acceleration assumed in the frame except for highly precise calculations (or the load factor).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="755" LastEditDate="2016-03-24T16:38:34.010" LastActivityDate="2016-03-24T16:38:34.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26377" PostTypeId="1" AcceptedAnswerId="26388" CreationDate="2016-03-24T01:55:43.447" Score="23" ViewCount="563" Body="&lt;p&gt;Reading about a &lt;a href=&quot;https://en.wikipedia.org/wiki/Nuestra_Se%C3%B1ora_de_las_Mercedes&quot;&gt;Spanish treasure ship&lt;/a&gt;, I found that it eventually created a dispute between the company that found it (Odyssey) and the Spanish government, so the following questions came to my mind (focused on an international ocean wreck):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the same ownership law applicable to wrecked ships and wrecked planes?&lt;/li&gt;&#xA;&lt;li&gt;Is there any difference between floating debris and sunk debris?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;More specifically, regarding &lt;a href=&quot;https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370#Debris_discoveries&quot;&gt;Malaysian Flight 370&lt;/a&gt;, who owns the debris discovered at La Réunion?&lt;/p&gt;&#xA;" OwnerUserId="6979" LastEditorUserId="62" LastEditDate="2016-03-24T11:10:14.157" LastActivityDate="2016-03-24T18:11:58.343" Title="Who owns wrecked airplanes in international waters?" Tags="&lt;accidents&gt;&lt;international&gt;&lt;regulations&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="26379" PostTypeId="1" AcceptedAnswerId="26384" CreationDate="2016-03-24T05:24:22.117" Score="8" ViewCount="3036" Body="&lt;p&gt;While reading this &lt;a href=&quot;https://aviation.stackexchange.com/questions/23372/why-cant-armrests-be-raised-on-window-and-aisle-seats&quot;&gt;question&lt;/a&gt;, I came across a little &lt;a href=&quot;http://www.milevalue.com/how-did-i-just-learn-this-awesome-trick-to-get-more-space-in-coach/&quot; rel=&quot;nofollow noreferrer&quot;&gt;trick&lt;/a&gt;, of how to lift up the locked arm-rests in window and aisle seats. Though I always wondered why they were locked, knowing that little trick now makes me wonder is it legal to lift locked arm-rests. Would it get me into any trouble with the cabin crews or the airline?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VJO5o.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VJO5o.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-03-29T09:49:50.467" Title="Is it ok to lift locked armrests on aisle or window seats?" Tags="&lt;seats&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26380" PostTypeId="1" CreationDate="2016-03-24T07:22:12.663" Score="11" ViewCount="3901" Body="&lt;p&gt;When I was flying with Swiss Air we hit some turbulence. Of course, the seat belt light came on but above the bathroom sign, a blue light came on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yASbX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yASbX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://studopedia.su/19_94191_Up-latch-release-button.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then after a while a second one came on. I'm just wondering if this has something to do with the turbulence or not.It was an Airbus A340 if that helps any. &lt;/p&gt;&#xA;" OwnerUserId="14161" LastEditorUserId="-1" LastEditDate="2016-03-28T12:14:51.893" LastActivityDate="2016-03-28T12:14:51.893" Title="What does a blue light by the toilet sign mean?" Tags="&lt;safety&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26381" PostTypeId="2" ParentId="26352" CreationDate="2016-03-24T08:27:54.173" Score="6" Body="&lt;p&gt;Before answering the questions, let's try to see how simple is the notion of a geodesic. In planar construction, we use latices to rigidify a structure, e.g. a truss:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vLElK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vLElK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The structure is made of straight segments that don't deform when axial forces are applied. If we switch from the plane to an arbitrary curved surface, something similar can be done, but geodesics take the place of the straight lines (actually the line is the geodesic for the plane).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The idea behind a geodesic construction is that its rigidity is obtained from segments on the surface of the truss, and the inner volume is left empty and available for other uses.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;What is the relation between geodesic airframe and geodesic curves?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Are geodesic frames related to geodesic curves? If yes, in what way?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Geodesic airframes are indeed constructions made of geodesics, a technique first applied to aviation by &lt;a href=&quot;https://en.wikipedia.org/wiki/Barnes_Wallis&quot; rel=&quot;nofollow noreferrer&quot;&gt;Barnes Wallis&lt;/a&gt;. From the Barnes Wallis Foundation, and article &lt;em&gt;&lt;a href=&quot;http://www.barneswallisfoundation.co.uk/life-and-work/geodetic-aircraft-design/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Geodetic Aircraft Design&lt;/a&gt;&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A geodetic (or geodesic) airframe makes use of a space frame formed&#xA;  from a spirally crossing basket-weave of load-bearing members. By&#xA;  having the geodesic curves form two helices at right angles to one&#xA;  another, the members became mutually supporting in a manner that the&#xA;  torsional load on each cancels out that on the other. In addition to&#xA;  being comparatively light and strong, the fact that the geodetic&#xA;  structure was all in the outer part of the airframe meant that the&#xA;  centre was a large empty space, ready to take payload or fuel.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Sz1Q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Sz1Q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;A close-up view of the geodetic structure designed by Barnes Wallis (&lt;a href=&quot;http://www.sirbarneswallis.com/Geodetics.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CnoF9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CnoF9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Vickers Wellington's under construction (&lt;a href=&quot;http://www.ww2warbirds.net/ww2htmls/vickwelling.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;[The &lt;a href=&quot;https://en.wikipedia.org/wiki/Geodesic&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia article&lt;/a&gt;] does not seem to deal with  geodesic curves. It is mostly about about a structure made by triangles or other polygons&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Geodesics are curved lines. Using 2 or 3 geodesics on a closed surface creates repetitive and symmetrical curved polygons, e.g. curved triangles and curved lozenges. Providing the supporting geodesics are angled so that &quot;&lt;em&gt;the torsional load on each cancels out that on the other&lt;/em&gt;&quot;, the resulting geometry belongs to the family of geodesic modeling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Whether the actual construction is an approximation of the perfect model is a different engineering/costing problem. This is related to the actual cancellation of the torsional loads after approximation and the effect of the residual loads on the structure. This residual load could potentially be absorbed by additional engineering device if appropriate. This dome is made of straight segments only, the triangles are planar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/SPZr9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/SPZr9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;The geodesic dome at Amundsen Scott South Pole Station by Ernie Mastroianni (&lt;a href=&quot;http://mastroianni.photoshelter.com/image/I0000v3XAvTVEGEE&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-25T15:04:18.037" LastActivityDate="2016-03-25T15:04:18.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26382" PostTypeId="2" ParentId="26377" CreationDate="2016-03-24T12:38:28.223" Score="6" Body="&lt;p&gt;&lt;a href=&quot;http://www.emsa.europa.eu/retro/Docs/marine_casualties/annex_13.pdf&quot; rel=&quot;noreferrer&quot;&gt;ICAO Annex 13&lt;/a&gt;, &lt;em&gt;Aircraft Accident and Incident Investigation&lt;/em&gt;, says that the country where the aircraft is registered is responsible for investigation and it (or the operator's country) makes the final decision on what to do with the wreckage.&lt;/p&gt;&#xA;&lt;p&gt;The &amp;quot;State of Registry&amp;quot; is responsible for investigation if the accident is in international waters:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;State of Registry&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;5.3 When the location of the accident or the serious incident cannot definitely be established as being in the territory of any State, the&#xA;State of Registry shall institute and conduct any necessary&#xA;investigation of the accident or serious incident. However, it may&#xA;delegate the whole or any part of the investigation to another State&#xA;by mutual  arrangement and consent.&lt;/p&gt;&#xA;&lt;p&gt;5.3.1 States nearest the scene of an accident in international waters shall provide such assistance as they are able and shall, likewise,&#xA;respond to requests by the State of Registry.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;And it (or the &amp;quot;State of the Operator&amp;quot;) decides who should take custody of the wreckage once the investigation is complete:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Release from custody&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;3.4 Subject to the provisions of 3.2 and 3.3, the State of Occurrence shall release custody of the aircraft, its contents or any parts&#xA;thereof as soon as they are no longer required in the investigation,&#xA;to any person or persons duly designated by the State of Registry or&#xA;the State of the Operator, as applicable.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Practically speaking, I assume that once an investigation is complete the wreckage is either scrapped or returned to the operator (airline) if it still has any value.&lt;/p&gt;&#xA;&lt;p&gt;In the case of MH370, that means that Malaysia as the State of Registry (and the State of the Operator) is responsible for investigation and for ownership of the wreckage. But I'm not a lawyer, so if you want a definitive answer then I suggest &lt;a href=&quot;http://law.stackexchange.com&quot;&gt;asking elsewhere&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-24T12:38:28.223" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26383" PostTypeId="2" ParentId="26380" CreationDate="2016-03-24T14:28:40.597" Score="3" Body="&lt;p&gt;There's a panel of lights. The blue one indicates that a passenger has pressed a call button. If it were a red light that means the crew is using the interphone to call one another. &lt;/p&gt;&#xA;" OwnerUserId="14164" LastActivityDate="2016-03-24T14:28:40.597" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26384" PostTypeId="2" ParentId="26379" CreationDate="2016-03-24T14:36:20.233" Score="11" Body="&lt;p&gt;I'll have a go at this, but this answer applies only to the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, is it legal? As far as I can see, yes. There are various regulations (e.g. &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=5fbbcc58dbe905fe53c2e7a691b7e06e&amp;amp;mc=true&amp;amp;node=se14.3.121_1317&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 121.317&lt;/a&gt;) about specific items that passengers have to be briefed on and comply with instructions on. They include smoking, seatbelts, emergency exits, screens and tables etc. But there's no explicit mention of armrests and I didn't see any generic clause like &quot;any other equipment&quot; or whatever. So in the absence of any explicit or general regulation that says you can't, I would say you can.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, will it get you &quot;into trouble&quot;? Maybe. As &lt;a href=&quot;https://aviation.stackexchange.com/a/23374/62&quot;&gt;the answer&lt;/a&gt; to a related question shows, the FAA doesn't want armrests to become an obstacle to evacuation and they advise crew members to make sure that armrests are locked down for takeoff and landing. Many airlines I've traveled on have an announcement about the armrests, even if there's no regulation that requires it. If the crew ask you to put your armrest down and you refuse then the 'best' thing that can happen is that they decide you're rude but not dangerous and let it go. But if you refuse repeatedly and they decide you're being confrontational or unlikely to follow other instructions then &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_111&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.11&lt;/a&gt; would apply:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may assault, threaten, intimidate, or interfere with a&#xA;  crewmember in the performance of the crewmember's duties aboard an&#xA;  aircraft being operated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Under that regulation, if the crew decides you're &quot;interfering&quot; with their duties (which include keeping you and everyone else safe), you'll probably get a police escort off the aircraft, especially if alcohol is involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But having said all that, I don't think this is a big deal at all. The FAA's concern seems to be about armrests that get stuck at an angle, not about ones that can be fully lifted. I've often seen passengers put up their armrests and I've never heard a crew member comment on it, but if they do ask you to lower them, arguing about regulations would probably be a bad idea.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-03-24T14:36:20.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26385" PostTypeId="1" AcceptedAnswerId="26387" CreationDate="2016-03-24T16:53:10.343" Score="15" ViewCount="23826" Body="&lt;p&gt;I am currently trying to study aircraft performance and I have some difficulties distinguishing between rate of climb and climb gradient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can someone explain what are the differences between the two of them?&lt;/p&gt;&#xA;" OwnerUserId="14165" LastEditorUserId="1696" LastEditDate="2018-04-13T20:03:58.633" LastActivityDate="2019-05-05T16:46:43.577" Title="What is the difference between rate of climb and climb gradient?" Tags="&lt;aircraft-performance&gt;&lt;climb&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26387" PostTypeId="2" ParentId="26385" CreationDate="2016-03-24T17:00:11.160" Score="14" Body="&lt;p&gt;The climb gradient is the percentage of the rise over run (100% if you are climbing at 45 degrees) that your aircraft is climbing at while the rate of climb is the speed at which you are climbing based off the airspeed and climb gradient (given in feet per minute).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2019-05-05T16:46:43.577" LastActivityDate="2019-05-05T16:46:43.577" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26388" PostTypeId="2" ParentId="26377" CreationDate="2016-03-24T18:11:58.343" Score="7" Body="&lt;p&gt;Insofar as it relates to MH370 the treaty sections Pondlife quoted would probably work quite smoothly if it were found by a government or someone working on behalf of the govt. The question arises as to what happens when James Cameron goes and finds it. (Inevitable, am I right?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is located by a private party then the law would not be quite so clear. It would fall to courts and there would be legal claims falling under &lt;a href=&quot;https://en.wikipedia.org/wiki/Admiralty_law?wprov=sfla1&quot;&gt;admiralty law&lt;/a&gt;, salvage law and those might even be superceded by laws governing criminal investigation at sea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally under ocean salvage law the original owner continues to own it, but the salvaging party is entitled to a substantial award or prize. To complicate matters, there are two international conventions on salvage law, &lt;a href=&quot;https://en.wikipedia.org/wiki/Brussels_Convention_on_Assistance_and_Salvage_at_Sea?wprov=sfla1&quot;&gt;one from 1910&lt;/a&gt; and a second &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Convention_on_Salvage?wprov=sfla1&quot;&gt;one from 1989&lt;/a&gt;. Some countries recognize one of them and object to the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If Malaysian Airlines is no longer in business when it's found that will make things even more unclear. Probably the best analog would be the Titanic case. The company that recovered most of the artifacts sued to be declared owner. A US court &lt;a href=&quot;http://www.theguardian.com/world/2009/oct/26/titanic-artefact-case&quot;&gt;declared jurisdiction and ruled&lt;/a&gt; that as compensation for the cost of recovery they had the right to &lt;em&gt;display&lt;/em&gt; the items, but they do not &lt;em&gt;own&lt;/em&gt; them. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;After a series of court battles, an American company, RMS Titanic Inc (RMST), emerged as the owner of the salvage rights, allowing it to keep possession and put on touring display the 5,900 artefacts it has lifted from the ship during six dives.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.theguardian.com/world/2009/oct/26/titanic-artefact-case&quot;&gt;From an article in The Guardian&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So far no one owns them since White Star Line is long gone. The US and UK quickly hashed together a treaty to declare them a public memorial so the artifacts can't be sold off to private collectors.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An international agreement signed by Britain and the US designates the Titanic as an international memorial and seeks to protect it from being plundered or damaged by unauthorised dives.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;from the same article*&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;With all these things at play there is simply no telling what would happen with it.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-24T18:11:58.343" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26389" PostTypeId="1" AcceptedAnswerId="26391" CreationDate="2016-03-24T18:15:51.083" Score="9" ViewCount="7509" Body="&lt;p&gt;In looking at all the sources of aviation data, including POH's, instrument dials, instructional materials, FAA publications, METAR's, flying magazine stories, YouTube videos, etc., I see no standard usage of either knots (nautical miles per hour), or mph (statute miles per hour).  It seems many people use them not interchangeably, but mix them up seemingly randomly.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any kind of agreed upon standard about when to use which system of units?  It's easy enough to convert one to the other (well actually a lot easier to convert knots to mph), but it seems this is just a latent trap for mistakes in navigating and, more importantly, in airspeed errors.&lt;/p&gt;&#xA;" OwnerUserId="9161" LastEditorUserId="9491" LastEditDate="2016-09-09T03:13:19.040" LastActivityDate="2020-05-11T00:45:28.963" Title="Knots vs MPH, is there some standard for when to use which unit?" Tags="&lt;airspeed&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26390" PostTypeId="2" ParentId="26389" CreationDate="2016-03-24T18:40:27.760" Score="4" Body="&lt;p&gt;Knots are used almost universally for marine and aviation navigation because a nautical mile relates directly to mapping of the earth.  A nautical mile is equal to 1 minute of latitude making it very easy to use Knots for speed and nautical miles for distance when already the earth's mapping uses degrees and minutes of latitude.  Each degree of latitude is equal to 60 minutes of latitude.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastEditorUserId="13424" LastEditDate="2016-03-24T22:02:23.860" LastActivityDate="2016-03-24T22:02:23.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26391" PostTypeId="2" ParentId="26389" CreationDate="2016-03-24T19:03:46.033" Score="5" Body="&lt;p&gt;According to the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-18.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Flight Navigators Handbook&lt;/a&gt; (the Flight Navigator Cert is rarely issued any more to my understanding but none the less).  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The standard unit of distance for navigation is the nautical mile&#xA;  (NM). The NM can be defined as either 6,076 feet or 1 minute of&#xA;  latitude&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It goes on to talk about speed &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Closely related to the concept of distance is speed, which determines&#xA;  the rate of change of position. Speed is usually expressed in miles&#xA;  per hour (mph), this being either SM per hour or NM per hour. If the&#xA;  measure of distance is NM, it is customary to speak of speed in terms&#xA;  of knots. Thus, a speed of 200 knots and a speed of 200 NM per hour&#xA;  are the same thing. It is incorrect to say 200 knots per hour unless&#xA;  referring to acceleration.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It seems it comes down to what you measure distance in, then simply report the appropriate speed units. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most pilots will calculate (and talk in units) based on the instrumentation in their plane. Some airspeed indicators contain both knots and MPH however its not uncommon for them to contain only a single unit (generally older GA planes is where I have seen MPH instruments). POH's will generally contain what ever unit the air speed indicators in the original build of the plane contained (some POHs will contain both units). Just to show some examples, &lt;a href=&quot;http://flyblueridgeaviation.com/wordpress/wp-content/uploads/2014/10/N3354X-POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mooney reported speeds in MPH in their older POH's&lt;/a&gt; while say a &lt;a href=&quot;http://www.wrongbrosftw.com/wp-content/uploads/2014/05/Warrior-PA28-161-POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper from that era shows Kts in its POH&lt;/a&gt;. For example this indicator contains both units.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8YEiW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8YEiW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;(&lt;a href=&quot;http://www.aircraftspruce.com/catalog/graphics/10-02216.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end of the day its most important that the units are not mixed up and or used interchangeably. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the errors in airspeeds this is one of the reasons that air speed indicators have color queues to indicate things like stall range, flap extend range and smooth air operating range. This way if a pilot does accidentally confuse units there are other things to rely on. (Side note there are some important speeds that do NOT appear on airspeed indicators that should always be noted).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;-Edit- &#xA;To answer the comments below. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I report distance in NM since thats what foreflight uses on its ruler function as well as its ring function (at least the way I have it set up). Most plotters I have seen are in NM so even if I had a paper map I would be reporting NM as well.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Im not sure the FAA has official declared that Knots are the only acceptable unit. MPH airspeed indicators are still considered air worthy so they must at least accept it on that level. There have been pushes to standardize instrumentation after the issues caused by the eastern vs. western attitude indicators but with the advent of glass cockpits most of these things can now be configurable in software and changed by a simple setting. The FAR's (such as 91.117) report speed in both KTS and MPH and that is the letter of the law from the FAA.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-25T21:43:29.530" LastActivityDate="2016-03-25T21:43:29.530" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26392" PostTypeId="2" ParentId="26380" CreationDate="2016-03-24T19:06:14.893" Score="19" Body="&lt;p&gt;You don't indicate which aircraft make and model you were flying in. I'm going to answer with some general information regarding Airbus aircraft, since that's the predominant manufacturer of &lt;a href=&quot;https://en.wikipedia.org/wiki/Swissair#Fleet&quot;&gt;aircraft currently in SwissAir's fleet&lt;/a&gt;. There may be subtleties from version to version.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;: a blue light typically indicates a passenger has pressed the &quot;call attendant&quot; button above their seat. It's used to provide a central indication that assistance is required, and may help localise the row the passenger is seated in by only illuminating a blue light in some parts of the aircraft in closest proximity to the relevant row.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Longer answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The panel with coloured lights to which you refer is the &lt;strong&gt;Area Call Panel&lt;/strong&gt; (ACP). These panels are situated at either end of the cabin, and possibly in the mid cabin or at other locations depending on aircraft type and age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ACP typically has multiple colour indications, such as &lt;strong&gt;pink&lt;/strong&gt;, &lt;strong&gt;blue&lt;/strong&gt;, &lt;strong&gt;amber&lt;/strong&gt; and &lt;strong&gt;green&lt;/strong&gt;. Their meaning is as follows:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;Pink&lt;/strong&gt;: communication from cockpit. Normally steady, flashing if an &lt;em&gt;emergency&lt;/em&gt; call is taking place (initiated in either direction: cockpit to cabin or cabin to cockpit).&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Blue&lt;/strong&gt;, steady: passenger call using at-seat attendant button in the &lt;strong&gt;passenger service unit&lt;/strong&gt; (PSU -- overhead panel above each seat row). This light may only appear on particular ACPs, which enables the calls to be segregated by cabin and further by seat location.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Amber&lt;/strong&gt;: assistance request from the lavatory. Steady indicates a passenger in the lavatory has requested assistance from an attendant. Flashing indicates a smoke detector activation.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Green&lt;/strong&gt;: attendant call, using the cabin interphone to call between interphone stations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The indication panel is integrated with, and receives event indications from, the Cabin Intercommunication Data System (CIDS). The CIDS is a crucial network on the aircraft responsible for handling crew communications, managing some aspects of the flight attendant displays, operating the speaker system and giving the relevant indications. Calls requiring attention from a flight attendant typically trigger a notification on the attendant loudspeakers and illuminate the relevant light on the ACP (unless already illuminated) in order to draw attention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, for passenger calls, the relevant seat number light in the PSU is illuminated when the attendant button is operated. This allows the request to be localised to the relevant row and side of the aircraft. If an aircraft door is open, the row number flashes -- typically a door open event leads to the PSU row indications to be illuminated to enable embarking passengers to find their seats more easily.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;References&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Only a small amount of information is publicly available about the ACP, its role in the CIDS and the CIDS more generally. The information here is corroborated by two sources:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A &lt;strong&gt;Lufthansa&lt;/strong&gt; training manual for the A319/320/321 aircraft, &lt;a href=&quot;https://www.scribd.com/doc/24949816/13/ATTENDANT-INDICATION-PANEL&quot;&gt;published online&lt;/a&gt;. See pages 166, &lt;em&gt;et seq.&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Jonathan Hurst&lt;/strong&gt;'s site, in particular the excerpts of &lt;a href=&quot;http://hursts.org.uk/airbus-technical/html/ar01s10.html&quot;&gt;A320 technical operations manuals, chapter 10 &quot;Cabin&quot;&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Any further sources or references, especially for non-A319/A32x models, are gratefully received in the comments.&lt;/p&gt;&#xA;" OwnerUserId="2032" LastEditorUserId="2032" LastEditDate="2016-03-24T19:35:37.470" LastActivityDate="2016-03-24T19:35:37.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26393" PostTypeId="2" ParentId="2443" CreationDate="2016-03-24T19:57:13.283" Score="16" Body="&lt;h1&gt;Relatively short answer&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Cospas-Sarsat: Feasible but...&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible, but there are many individual elements involved. It's a matter of probability that most of the time there will be a combination preventing the link to work. If you know what to do and take care of ensuring a good direct &lt;a href=&quot;https://en.wikipedia.org/wiki/Line-of-sight_propagation&quot; rel=&quot;noreferrer&quot;&gt;line of sight&lt;/a&gt; (LOS) you may be able to avoid some of these combinations. It cannot work underwater.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Parameters that can attenuate the signal reaching the satellite receiver are of different origins:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The aircraft design itself (composite materials or aluminum, number of windows, ...)&lt;/li&gt;&#xA;&lt;li&gt;The location of the accident (canyon, trees, ...)&lt;/li&gt;&#xA;&lt;li&gt;The transmitter use (position, window proximity, metallic surface or debris interference, body proximity, ...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm not aware of experiment results for using a PLB within a metallic container like a commercial aircraft cabin. It's still possible to evaluate the RF channel loss in different configuration and see if the signal can reach the receiver with the minimum required level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As explained in the next sections about the Sarsat satellites of the international SAR service on 406 MHz:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The threshold for signal reception by the receiver is 161 dBW.&lt;/li&gt;&#xA;&lt;li&gt;With an initial power of 7 dBW (5 W), the attenuation must be at most 168 dB&lt;/li&gt;&#xA;&lt;li&gt;In good conditions we can expect an attenuation of &quot;only&quot; 148.1 dB. Such signal 12.9 dB stronger that the threshold can be detected easily.&lt;/li&gt;&#xA;&lt;li&gt;In degraded conditions we may experiment an attenuation of 177.5 dB. Being 9.5 dB below the threshold, this signal is not detected.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Indoor transmission put the system at its limits of detection capability (a S-meter unit is 6 dB).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gApyo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gApyo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Weak signal on a S-meter, S-unit is 6 dB (&lt;a href=&quot;http://www.universal-radio.com/used/sold070.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many small attenuation causes that, when summed, can prevent the link to work must be taken into account, hence this answer is a long one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;SPOT LLC&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SPOT LLC solution you mention is a commercial messaging initiative working on 1.6 GHz, out of the Cospas-Sarsat system. Higher frequency means higher attenuation. The limited 0.4 W RF output also makes the signal weaker. It's very unlikely that SPOT could work within the cabin.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Details&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Introduction: PLB principles&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Emergency PLB operate on 406 MHz. The previous 121.5 MHz civil frequency is not monitored anymore by SAR satellites, but can be used (in addition of the actual signal at 406 MHz) as a homing guide for the SAR team. They are informed about whether this homing feature is active or not by the message sent by the PLB.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;PLB output power is 5 W (equivalences: 7 dBW 37 dBm) at 406 MHz, in vertical polarization. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;From &lt;a href=&quot;http://vnmcc.vishipel.vn/images/uploads/attach/T004.PDF&quot; rel=&quot;noreferrer&quot;&gt;C/S T.004&lt;/a&gt;, the performance of the satellite system is:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A &quot;&lt;em&gt;probability better than 95% to provide a valid solution (15 hexa identification provided) for a beacon transmitting with a 37 dBm output power (with a whip  antenna) and for satellites passes with elevation above 5°)&lt;/em&gt;&quot;&lt;/li&gt;&#xA;&lt;li&gt;A &quot;&lt;em&gt;probability better than 95% to provide a Doppler location with an accuracy better than 5 km&lt;/em&gt;&quot;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There are no satellites entirely dedicated to the SAR service, rather distress signal receivers are carried as one of the payloads aboard satellites. The system is made of two constellations:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;GEOSAR constellation, Geostationary Earth Orbit SAR. These satellites are at fixed positions, 36,000 km above the equator, and are covering the globe except the polar regions.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;LEOSAR, Low Earth Orbit SAR. Satellites in near-polar (about 85°). LEOSAR is made of two sub-constellations: Sarsat satellites orbiting at 850 km, and Cospas satellites orbiting at 1,000 km.&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/tCNiW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tCNiW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://oceansignal.com/fr/how-do-epirbs-and-plbs-operate/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A third constellation is planned to operate at a higher altitude than LEOSAR (MEOSAR, currently not fully deployed).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;While GEOSAR are likely to be first to detect the PLB activation due to their permanent LOS, LEOSAR will provide the best detection due to the shorter distance to the device.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'll focus on LEOSAR / Sarsat payload which provides the best chances for the detection of a PLB signal partially blocked by RF impermeable obstacles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Sarsat payloads&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Satellites carrying a LEOSAR Sarsat payload are &lt;a href=&quot;http://www.n2yo.com/satellite/?s=25338&quot; rel=&quot;noreferrer&quot;&gt;NOAA 15&lt;/a&gt; (Sarsat 7), &lt;a href=&quot;http://www.n2yo.com/satellite/?s=28654&quot; rel=&quot;noreferrer&quot;&gt;NOAA 18&lt;/a&gt; (Sarsat 10), &lt;a href=&quot;http://www.n2yo.com/satellite/?s=33591&quot; rel=&quot;noreferrer&quot;&gt;NOAA 19&lt;/a&gt; (Sarsat 12). Other are scheduled to be active in the future (some may be already, I haven't checked). They are fitted with a SAR receiver (search and rescue processor, SARP). Sarsat satellites can be tracked on &lt;a href=&quot;http://www.n2yo.com/satellites/?c=7&quot; rel=&quot;noreferrer&quot;&gt;N2YO.com&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;em&gt;Cospas-Sarsat LEOSAR Space Segment Commissioning Standard&lt;/em&gt; - &lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/T4OCT29.09.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S T.004&lt;/a&gt;, a SARP-2 has a sensitivity of -161 dBW, and SARP-3 -164 &lt;a href=&quot;https://en.wikipedia.org/wiki/Decibel_watt&quot; rel=&quot;noreferrer&quot;&gt;dBW&lt;/a&gt; (that's about 60 &lt;a href=&quot;https://en.wikipedia.org/wiki/Metric_prefix&quot; rel=&quot;noreferrer&quot;&gt;attowatts&lt;/a&gt; to be compared with a &lt;a href=&quot;https://docbox.etsi.org/workshop/2013/201310_eeworkshop/s04_ee_applicationofmethodologies/nsn_scheck.pdf&quot; rel=&quot;noreferrer&quot;&gt;cellular phone cell&lt;/a&gt;: -134 dBW, 1,000 times less sensitive).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can this small quantity be delivered to the SARP from the inside of a cabin?.. This is a matter of knowing the initial power, and determining the loss along the wave path until the signal reaches the receiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power generated by the transmitter amplifier is 5 W, or 7 dBW. 161 dBW on the receiver means receiving a 1 W signal that has been attenuated by 161 dB. If we have already 7 dBW at the source, we can bear a maximum attenuation of 168 dB.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Main loss inventory&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Propagation loss in direct view&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most important part of the signal will be lost in the atmosphere between the antenna of the PLB and the antenna of the SARP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KspQK.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KspQK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Loss due to distance&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Loss is dependent on two factors: distance and wavelength. Both factors limit the area of the receiving antenna compared to the whole sphere of the wave front, and in consequence the portion of energy received is smaller too.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Using the propagation model &lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.525-2-199408-I!!PDF-E.pdf&quot; rel=&quot;noreferrer&quot;&gt;ITU-R P.525&lt;/a&gt; (free-space propagation).&lt;/li&gt;&#xA;&lt;li&gt;Distance = 850 km, f = 406 MHz.&lt;/li&gt;&#xA;&lt;li&gt;Assuming &lt;a href=&quot;https://en.wikipedia.org/wiki/Isotropic_radiator&quot; rel=&quot;noreferrer&quot;&gt;isotropic antennas&lt;/a&gt; for the time being.&lt;/li&gt;&#xA;&lt;li&gt;According to the model, the loss (dB) is:&lt;BR&gt;&#xA;&lt;code&gt;Lbf = 20 log(4πd/λ)&lt;/code&gt;&lt;BR&gt;&#xA;&lt;code&gt;.   = 32.4 + 20 log(f) + 20 log(d)&lt;/code&gt;&lt;BR&gt;&#xA;&lt;code&gt;.   = 32.4 + 20 log(406) + 20 log(850)&lt;/code&gt;&lt;BR&gt;&#xA;&lt;code&gt;.   = 143 dB&lt;/code&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The signal that left the PLB antenna reaches the SARP antenna -143 dB weaker, assuming the best antenna alignment. But this is never the case, because when in a polar orbit, the satellite is unlikely to be exactly above the beacon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Misalignment of the receiving antenna&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There will be an angle between the nadir of the SARP and the beacon. This off-nadir angle, depends on the actual track of the satellite for the current orbit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p4k3q.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p4k3q.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Target off-nadir&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The gain of the antenna varies according to this angle. Sarsat-TIROS SARP Receive Antenna (UDA) Gain Pattern:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/24u3F.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/24u3F.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;UDA antenna gain at different off-nadir angles (&lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1478-1-200405-S!!MSW-E.doc&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming the &lt;a href=&quot;https://en.wikipedia.org/wiki/Polarization_%28waves%29&quot; rel=&quot;noreferrer&quot;&gt;polarization&lt;/a&gt; is favorable (RHCP), the gain may varies between +2 dB and -10 dB. Note that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The gain is better when the off-nadir angle is large. This is likely to compensate the higher distance to the beacon.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;I'll assume a link length f 850 km, but the actual length is larger when the beacon is not directly at the satellite's nadir.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;We should now work with the probability distribution of the misalignment for the LEOSAR antennas to have the full range of possibilities and their likelihood (e.g. &lt;a href=&quot;https://en.wikipedia.org/wiki/Monte_Carlo_method&quot; rel=&quot;noreferrer&quot;&gt;Monte-Carlo&lt;/a&gt; simulation). To simplify, let's just use a bad case: -4.4 dB (this is not the worst possible). Loss so far: -147.4 dB (-143 - 4.4).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Attenuation due to feeder and duplexer&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the satellite, the SARP is connected to an antenna via a duplexer to isolate the SARP uplink antenna from the SARR downlink signal (SAR repeater used on local mode, not detailed here):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mLMaw.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mLMaw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Hardware on the Sarsat satellite (&lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1478-1-200405-S!!MSW-E.doc&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The duplexer + feeder loss is -1.6 dB. Loss so far: -149 dB (-147.4 - 1.6).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Loss margin left&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We had a budget for -168 dB loss, we have used -149 dB. The margin until the PLB signal is lost by the SARP is 19 dB, assuming we are in this configuration:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;PLB is outdoor.&lt;/li&gt;&#xA;&lt;li&gt;The LOS is completely clear, no foliage, no roof, etc.&lt;/li&gt;&#xA;&lt;li&gt;PLB antenna has no gain/loss (0 dB gain).&lt;/li&gt;&#xA;&lt;li&gt;PLB antenna is vertical, this is the normal use of the SAR device.&lt;/li&gt;&#xA;&lt;li&gt;PLB antenna and RF output stage &lt;a href=&quot;https://en.wikipedia.org/wiki/Standing_wave_ratio&quot; rel=&quot;noreferrer&quot;&gt;impedances match (no SWR)&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;There is no atmospheric loss (free space)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional losses&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's time to re-look at the assumption made until here, and take into account the additional effects encountered when the PLB is used from the cabin of a crashed aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;PLB is outdoor.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Actually the PLB is behind a cabin window.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;From &lt;a href=&quot;http://www.plexiglas.com/export/sites/plexiglas/.content/medias/downloads/sheet-docs/plexiglas-optical-and-transmission-characteristics.pdf&quot; rel=&quot;noreferrer&quot;&gt;Arkema&lt;/a&gt;:&lt;BR&gt;&#xA;&quot;&lt;em&gt;Most formulations of colorless Plexiglas sheet readily transmit standard broadcast, television and most radar waves of the electromagnetic spectrum&lt;/em&gt;&quot;. It can been assumed that windows (including the internal protection sheet) don't block the PLB signal. Loss = 0 dB.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the cabin, numerous reflections will occur on the wall, and due to the closed space with only small windows, it's likely the reflected signals will globally interfere in a destructive way (phase mismatch) with the original signal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If the PLB is displaced, even by a small amount, the reflections are changed. The RF energy actually vary continuously, creating a &lt;a href=&quot;https://en.wikipedia.org/wiki/Fading&quot; rel=&quot;noreferrer&quot;&gt;fading&lt;/a&gt; effect. Reflections has been studied in somehow comparable environments, for UHF frequencies. While the frequency was a bit higher, and the environment was a simple one, we can use the results for a rough order of magnitude:&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/xqs21.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xqs21.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;RFID signal (915 MHz) loss due to reflections (&lt;a href=&quot;http://www.ee.washington.edu/faculty/nikitin_pavel/papers/RFID_2008.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;BR&gt;The spatial fading is visible, at some distances reflected signals add, at other they subtract. This loss is also known as &lt;em&gt;multipath&lt;/em&gt; effect. The signal may be attenuated by 10 dB or more compared to free space.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Each reflection has also the potential to change the polarization. See next point.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;PLB antenna is vertical, this is the normal use of the SAR device.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The transmitter and receiver antenna polarization must match or an attenuation occurs. The polarization of an antenna describes the plane in which the electric field is transmitted. For a simple antenna, made of a single active element, the electric field is sent in the plane of the element:&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/V05pE.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V05pE.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Vertically and horizontally polarized waves (&lt;a href=&quot;http://www.kenbotong.com/Applications/Antenna-Knowledge/46.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Vertical polarization creates less reflection on the ground, which is usually what is desired, so a PLB creates a vertical polarization, but only if the antenna is kept vertical, else the polarization will follow the antenna orientation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To cop with both linear vertical and horizontal polarizations, and everything in between, the SARP antenna is designed to be circularly polarized, and is able to receive both in good conditions, but not optimal conditions:&lt;BR&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;linearly polarized antennas will work with circularly polarized&#xA;  antennas and vice versa. However, there will be up to a 3 dB loss in&#xA;  signal strength. In weak signal situations, this loss of signal may&#xA;  impair communications (&lt;a href=&quot;http://www.astronwireless.com/topic-archives-antennas-polarization.asp&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&lt;/li&gt;&#xA;&lt;li&gt;The antenna on the satellite should be like this:&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/jddqb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jddqb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Helical, circularly polarized, antenna (&lt;a href=&quot;http://www.tacoantenna.com/product-list.php&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The LOS is completely clear, no foliage, no roof, etc.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Indeed, if there is a metallic obstacle in the LOS &lt;em&gt;and&lt;/em&gt; there is no possibility for reflections (no hole in the metallic cabin), no signal is transmitted. This could happen if the PLB were surrounded by metallic debris from the airplane wreckage.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Else there is a volume (the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fresnel_zone&quot; rel=&quot;noreferrer&quot;&gt;Fresnel zone&lt;/a&gt;) between the transmitter and the receiver that must be free of obstacles. This zone is an ellipsoid around the LOS. If obstacles are present there will be diffraction and reflection. Diffraction scatters the signal (no need to have knife-edge corners), and reflection deviates it, which could be a positive effect when there is no clear LOS.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dense vegetation or heavy foliage on the LOS: There is water in plants, a loss occurs, typically larger than 0.1 dB/m at 406 MHz. We can use models to evaluate the attenuation:&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/iqYdl.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iqYdl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Source, page 155)&lt;/sup&gt;&lt;BR&gt;&#xA;&lt;BR&gt;Example: The aircraft crashed in a forest. The aircraft is surrounded by 25 m trees, except in the direction from which it came.&lt;BR&gt;&#xA;&lt;BR&gt;Satellites low on the horizon will not be accessible: GEOSAR satellites over the equator are usually low on the horizon when viewed for medium latitudes, and some orbits of LEOSAR will be hidden by the trees due to the loss exceeding -15 dB as soon as the depth of foliage is 50 m (slant depth). This depth can be quickly encountered, leaving a small free field of view from a window (it would be larger for the windshield though):&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/BEutu.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BEutu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Tree trench created by crash-landing in a forest&lt;/sup&gt;  &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;PLB antenna has no &lt;a href=&quot;https://en.wikipedia.org/wiki/Antenna_gain&quot; rel=&quot;noreferrer&quot;&gt;gain/loss&lt;/a&gt; (0 dB gain).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This is likely the case for many PLB. PLB antenna seems to be a shortened 1/4 λ whip. Antennas are measured against an hypothetical perfect antenna (isotropic antenna), and the ratio of amplification is expressed in dBi (dB comparing to isotropic). dBi and dB are equivalent in the current discussion as the isotropic antenna has a gain of 0 dB.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;PLB antenna and RF output stage &lt;a href=&quot;https://en.wikipedia.org/wiki/Standing_wave_ratio&quot; rel=&quot;noreferrer&quot;&gt;impedances match (no SWR)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In order for the current out of the PLB RF amplifier to be radiated entirely by the antenna, PLB output impedance and antenna impedance must be equal. As soon as there is a mismatch, a part of the RF current is not converted into an electromagnetic wave and returns to the amplifier, mixing with the current flowing in the other direction. The result is the appearance of &lt;em&gt;standing waves&lt;/em&gt; in the PLB device. The ratio of SW is smartly named &lt;a href=&quot;https://en.wikipedia.org/wiki/Standing_wave_ratio&quot; rel=&quot;noreferrer&quot;&gt;SW ratio (SWR)&lt;/a&gt;. PLB are stated having a SWR less than 1.5 or 2 in their specifications. The &lt;a href=&quot;http://www.csgnetwork.com/vswrlosscalc.html&quot; rel=&quot;noreferrer&quot;&gt;corresponding loss&lt;/a&gt; is 0.2 and 0.5 dB. Not so much.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The impedance of the antenna varies greatly as soon as the antenna is not in a free space. A common cause is that a part of the body (containing water) is close to the antenna, or touching it. This could easily lead to a loss of 10 dB. The radiative efficiency of the antenna (gain) also suffers: Touching the antenna is like deforming it. Its characteristics are changed. For example is is no more optimized for the signal frequency to radiate. So in addition of SW appearance, the current that reaches the radiator is also poorly converted into waves. In your scenario it is important to use the PLB as intended, the antenna being unobstructed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There is no atmospheric loss (free space).&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;This is another effect difficult to estimate, as it varies with time of the day, weather aspects and Sun activity.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Oxygen and water vapor play an important role. From &lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.676-10-201309-I!!PDF-E.pdf&quot; rel=&quot;noreferrer&quot;&gt;ITU-R P.676-10&lt;/a&gt;:&lt;BR&gt;&#xA;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/FIZub.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FIZub.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Attenuation in dB per km (&lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.676-10-201309-I!!PDF-E.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;br&gt;&#xA;&lt;BR&gt;It seems for UHF the absorption is rather limited, so let's ignore it.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Other losses are due to sporadic electrical activities in the ionosphere. They are more difficult to estimate, and they translate into noise rather than attenuating the signal received by the SARP. Other elements like the capability of the SARP to reject noise would also need to be considered.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Ionosphere anomalies could potentially introduce errors in the Doppler localization.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Bottom line&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's recapitulate the losses we have discussed:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; - Impedance mismatch / SWR:                 -0.5 dB&#xA; - Transmitter antenna gain:                 +0 dB&#xA; - Reflection in the cabin:                  -0 to -10 dB (center).&#xA; - Cabin window:                             -0 dB&#xA; - Fresnel obstruction and trees:            -0 to -15 dB&#xA; - Free space loss:                          -143 dB&#xA; - Absorption by atmosphere gases            -0 dB&#xA; - Other propagation losses:                 Not evaluated.&#xA; - Off-nadir angle:                          -0 to -4.4 dB&#xA; - Linear to circular polarization mismatch: -3 dB&#xA; - Satellite duplexer:                       -1.6 dB&#xA;&#xA;                               Acceptable:   -168   dB&#xA;                               Best case:    -148.1 dB&#xA;                               Worst case:   -177.5 dB&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;The worst case is encountered when:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The PLB experiments the higher level of reflected waves. This can be eliminated by being very close to the window, and shielding the rest of the cabin with something metallic, but not too close.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Fresnel ellipsoid is blocked by trees. Not much freedom here. LEOSAT will hopefully have orbits with sufficient high elevation to be out of the obstacles. If the aircraft is really covered by deep foliage, there is no much chance for a successful link.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The aircraft is at the nadir of the satellite. The SARP antenna is optimized for off-nadir locations (no sure off-nadir locations will be better served, due to the increased slant distance, that would need to be checked). Too bad if the aircraft is in a forest.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Note that carrying a personal locator doesn't cause a safety problem, as it doesn't transmit before being activated. Activation will be either manual (usually for PLB) or by sensing a large acceleration (seems limited to ELT). I don't know if the security guys at the airport will let you board with a transmitter. It should be easier to persuade the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Case of a SPOT device&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compared to the numerous documents that describe governments-financed SAR service on 406 MHz, SPOT is a more confusing solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not related to &lt;a href=&quot;http://www.geo-airbusds.com/en/147-spot-6-7-satellite-imagery&quot; rel=&quot;noreferrer&quot;&gt;SPOT&lt;/a&gt;, the observation satellite family built by Astrium. GEOS IERCC (International Emergency Response Coordination Center) has no link with the &lt;a href=&quot;http://gmao.gsfc.nasa.gov/GEOS/&quot; rel=&quot;noreferrer&quot;&gt;GEOS satellites family&lt;/a&gt; launch by Nasa some decades ago. It is not either &lt;a href=&quot;https://fr.wikipedia.org/wiki/Geostationary_Operational_Environmental_Satellite&quot; rel=&quot;noreferrer&quot;&gt;GOES&lt;/a&gt;, the geostationary satellites that support GEOSAR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.globalstar.com/en/&quot; rel=&quot;noreferrer&quot;&gt;Globalstar&lt;/a&gt; is a large satellite phone company owning satellites. &lt;a href=&quot;http://www.findmespot.com/en/&quot; rel=&quot;noreferrer&quot;&gt;SPOT LLC&lt;/a&gt; is a subsidiary of Globalstar providing satellite data links and related sets for messaging and voice communications. &lt;a href=&quot;http://www.geosalliance.com/&quot; rel=&quot;noreferrer&quot;&gt;GEOS-Alliance&lt;/a&gt; has launched a privately-owned assistance service based on SPOT capabilities. GEOS-Alliance services are sold online, and by retaillers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From SPOT website:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;SPOT Gen3 provides location-based messaging and emergency notification&#xA;  technology that allows you to communicate from remote locations around&#xA;  the globe. It offers custom tracking interval options,&#xA;  motion-activated tracking, long-life battery and more.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In short:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Instead of buying a SAR transmitter and then having the service for free, the GEOS-Alliance subscriber receives a transmitter and pays an annual fee.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Instead of having the SAR device connected to the SAR organizations worldwide through the &lt;a href=&quot;http://www.unoosa.org/pdf/sap/2006/safrica/presentations/03-01-02.pdf&quot; rel=&quot;noreferrer&quot;&gt;LUTs&lt;/a&gt; and &lt;a href=&quot;http://www.sarsat.noaa.gov/UN_USA08/2009%20USA%20AFRCC.pdf&quot; rel=&quot;noreferrer&quot;&gt;MCCs/RCCs&lt;/a&gt;, the subscriber is connected to GEOS which calls the local emergency services on your behalf.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The technology behind:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;SPOT/Globalstar seems to use LEO spacecraft at 1,414 km instead of 850 km for Sarsat, with a 52° inclination instead of 85°, meaning their coverage could be reduced.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;SPOT messengers are limited to 0.4 W instead of 5 W for Sarsat, maybe because of regulations, as they can be used without actually signaling a distress situation.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Globalstar frequency used is 1.6 GHz, instead of 406 MHz for Sarsat.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It seems that these three technical differences are not going to make SPOT devices as efficient as Sarsat:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Using the same &lt;a href=&quot;https://www.itu.int/dms_pubrec/itu-r/rec/p/R-REC-P.525-2-199408-I!!PDF-E.pdf&quot; rel=&quot;noreferrer&quot;&gt;ITU-R P.525&lt;/a&gt;: Lbf = 20 log(4πd/λ) gives a free space loss of 159 dB upfront, to be compared to the 143 dB for Sarsat (difference: -16 dB).&lt;/li&gt;&#xA;&lt;li&gt;0.4 W = -4 dBW instead of 7 dBW for Sarsat (difference: -11 dB).&lt;/li&gt;&#xA;&lt;li&gt;We may add a loss of 1 dB for the atmosphere absorption at this frequency.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If I'm not wrong, that's already a difference of -28 dB at the receiver. It must be very sensitive, or be liked to hi-gain antennas to compete with the governments-operated SAR. That's not going to make it from within the cabin of an aircraft with a limited LOS, and sometimes this seems to even &lt;a href=&quot;http://14erskiers.com/franksblog/2010/06/spot-gps-messengers-worth-it-or-worthless/&quot; rel=&quot;noreferrer&quot;&gt;not work well&lt;/a&gt; in the open space.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;Reference documents&lt;/h1&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/A-003-DEC-2015.pdf:%20Cospas-Sarsat%20System%20Monitoring%20and%20Reporting&quot; rel=&quot;noreferrer&quot;&gt;C/S A.003&lt;/a&gt;: Cospas-Sarsat System Monitoring and Reporting&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/CS-G003-OCT-2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S G.003&lt;/a&gt;: Introduction to the Cospas-Sarsat System&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/G4OCT28E.99D.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S G.004&lt;/a&gt;: Cospas-Sarsat Glossary&lt;/li&gt;&#xA;&lt;li&gt;C/S G.006: Cospas-Sarsat System Assessment&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/CS-G008-OCT-2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S G.008&lt;/a&gt;: Operational Requirements For Cospas-Sarsat Second Generation. 406 Mhz Beacons&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/T-001-DEC-2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S T.001&lt;/a&gt;: Specification for Cospas-Sarsat 406 MHz Distress Beacons&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/CS-T.003_OCT-14.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S T.003&lt;/a&gt;: Description of the Payloads Used in the Cospas-Sarsat LEOSAR System&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/T-004-DEC-2015.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S T.004&lt;/a&gt;: Cospas-Sarsat LEOSAR Space Segment Commissioning Standard&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.cospas-sarsat.int/images/stories/SystemDocs/Current/CS-T011-OCT-2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;C/S T.011&lt;/a&gt;: Description of the 406 Mhz Payloads Used in the Cospas-Sarsat GEOSAR System&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;More Sarsat documentation: &lt;a href=&quot;http://www.cospas-sarsat.int/en/documents-pro/system-documents&quot; rel=&quot;noreferrer&quot;&gt;Cospas-Sarsat site&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-03-29T08:19:57.293" LastActivityDate="2016-03-29T08:19:57.293" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26394" PostTypeId="2" ParentId="26385" CreationDate="2016-03-24T21:02:57.720" Score="10" Body="&lt;p&gt;A climb &lt;strong&gt;&lt;em&gt;gradient&lt;/em&gt;&lt;/strong&gt; is a geometry problem -- the relationship of two points in 3-dimensional space... to get from one to the other you gain X' in Y NM, so you have X/Y feet per nautical mile as a climb gradient.  Or it can be expressed in percent slope -- the two terms are different ways of describing the same thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A climb &lt;strong&gt;&lt;em&gt;rate&lt;/em&gt;&lt;/strong&gt; is simply speed in the vertical dimension, X feet gained per minute.  It is typically read on the Vertical Speed Indicator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two come together when the discussion turns to &quot;what climb performance is required to clear an obstacle.&quot;  The surveyors determine the &lt;strong&gt;geometry&lt;/strong&gt; between a starting point (such as, the end of the runway at 35' AGL) and an end point (an obstacle at some distance from the end of the runway with a given height, plus a prescribed amount of clearance).  Then they publish this as a required climb &lt;strong&gt;&lt;em&gt;gradient&lt;/em&gt;&lt;/strong&gt; which will ensure that you'll cross the obstacle with the required clearance.  They don't know, or care, what speed you'll be flying; they've surveyed the geometry of the runway and obstacle and applied the regulatory 'required clearance', so their work here is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the pilot in the cockpit, though, I don't have a way to determine my climb gradient at a glance.  Performance computers will do that and typically work the calculations to determine how much weight I can take off with, in order to have adequate climb capability, and at some lighter weight they may tell me what my climb gradient will actually be.  But it's not a value that I can read off of an instrument as I'm flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a given groundspeed, flying exactly &quot;this&quot; climb gradient will yield &quot;that&quot; vertical speed... define any two and the third can be calculated.  So you will often see charts that tell you at various groundspeed values, what vertical speed you will need to maintain in order to achieve the necessary gradient.  So the two concepts are related, but nevertheless distinct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8365/difference-between-best-rate-of-climb-and-maximum-rate-of-climb&quot;&gt;not-really-a-duplicate question&lt;/a&gt; shows, the airspeed that will give the best climb &lt;strong&gt;&lt;em&gt;gradient&lt;/em&gt;&lt;/strong&gt; is not necessarily the airspeed that will give the best climb &lt;strong&gt;&lt;em&gt;rate&lt;/em&gt;&lt;/strong&gt;.  Normally those are referred to as Vx and Vy -- best angle of climb speed (best gradient -- most vertical distance climbed per distance of forward travel) is Vx, and best rate of climb speed is Vy (best rate of climb speed -- most altitude gained per unit of time).  The Vy speed is typically faster than Vx.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-03-24T21:08:37.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26396" PostTypeId="1" AcceptedAnswerId="26398" CreationDate="2016-03-25T02:01:08.820" Score="18" ViewCount="16372" Body="&lt;p&gt;A high-wing aircraft is considered to be more stable in a side-slip because of the pendulum effect. How does the pendulum effect increase stability in high wing aircraft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This question is about high-wing stability, not about comparisons between low and high-wing design also in the question that talks about pros and cons of high and low-wing design, it doesn't really explain the stability from an aerodynamic point of view.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-04-01T21:59:37.430" LastActivityDate="2019-05-31T12:29:30.510" Title="Why are high-wing aircraft more stable?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26397" PostTypeId="1" CreationDate="2016-03-25T09:55:42.680" Score="4" ViewCount="3668" Body="&lt;p&gt;I am reviewing autopilot requirements which mention that whenever an aircraft's altitude changes as a result of air disturbance or an out of trim condition, the inertial sensors will detect this change and an error signal is developed and fed to the relevant control channel, amplified, and applied to the servo actuator so that flight control surface can  be moved. &#xA;My question is what is out-of-trim condition? Is it something related to setting trim for constant speed?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="12220" LastEditDate="2016-03-27T20:53:21.037" LastActivityDate="2016-03-27T20:53:21.037" Title="What is an out-of-trim condition and how is it detected?" Tags="&lt;autopilot&gt;&lt;trim&gt;&lt;trim-tab&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26398" PostTypeId="2" ParentId="26396" CreationDate="2016-03-25T10:26:06.790" Score="23" Body="&lt;p&gt;Are they really?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a high wing aircraft the center of lift is above the center of gravity. This will not increase stability when the aircraft banks, however, as you rightly say, will help once the aircraft is in a sideslip. In order to keep the fuselage at an angle to the airflow, the wing has now to create a sideways lift component, which it does by flying at an angle to the horizontal. This roll angle of the aircraft will shift the center of gravity sideways, so it is not exactly below the center of lift, but offset laterally. This lateral offset seems to produce a rolling moment which works against the roll angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below I sketched the major forces in a sideslip. Note that the aircraft has a sideways speed component which creates a side force on fuselage and tail (green) which needs to be counteracted by the sideways component of lift (blue).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E3RZT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E3RZT.png&quot; alt=&quot;Short Sandringham in sideslip&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short Sandringham in sideslip (based on &lt;a href=&quot;http://www.seawings.co.uk/images/Sandringham%20-%20Plans/Sandringham%20Plan%20-%201.jpg&quot; rel=&quot;noreferrer&quot;&gt;this source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But still the weight (black) is attacking at the center of gravity, so it will not roll the aircraft, and the lift is in the vertical plane of symmetry, so it, too, will not create a rolling moment. Ergo, we have no stabilizing effect due to the high wing location!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a sideslip of a high-wing aircraft the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12099/why-do-low-wing-aircraft-have-higher-dihedral-than-high-wing-aircraft/12101#12101&quot;&gt;windward wing root will see a slightly increased angle of attack while the leeward wing root will experience a reduced angle of attack due to the crossflow around the fuselage&lt;/a&gt;. This would indeed create a rolling moment because it will shift the center of lift sideways, out of the plane of symmetry. In a static sideslip the pilot will deflect the ailerons to maintain the roll angle as well as the rudder to maintain the sideslip, shifting the lift vector back into the vertical plane of symmetry. Now any stabilizing effect of the lift asymmetry is on purpose cancelled by the pilot!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this is achieved in a low wing airplane by adding dihedral. Therefore, a low wing aircraft can easily be made as stable as a high wing aircraft in a sideslip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will notice that the lateral aerodynamic force (green) acts above the center of gravity and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5239/would-a-vertical-stabilizer-that-extends-both-above-and-below-the-centerline-be/5242#5242&quot;&gt;also produces a correcting rolling moment&lt;/a&gt;. This is dictated by the location of the vertical tail, which contributes little to the location of the center of gravity, but produces a considerable share of the lateral force (reduced in the sideslip case by rudder deflection, however). This rolling moment, though, is almost independent of wing location. In a low wing, the center of gravity will be lower in total, especially when the engines are mounted on the wing, so the rolling moment contribution of the vertical tail is somewhat higher. The effect is small in a sideslip since the rudder deflection means that the fuselage contributes the majority of the side force. And this is not &lt;strong&gt;the pendulum effect&lt;/strong&gt; which you asked about and which &lt;strong&gt;does not exist&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airships, &lt;a href=&quot;https://aviation.stackexchange.com/questions/24862/why-do-blimps-have-fins/24866#24866&quot;&gt;the pendulum effect is real&lt;/a&gt;, however: Since buoyancy always acts against gravity, a lateral offset of the heavy gondola will create an uprighting moment, just as it does in a pendulum. When turning, the heavy gondola will be pulled sideways by centrifugal forces, and the airship will roll. Since the turn is commanded with rudder, the rotation will give the rudder a small nose-down moment, which must be compensated by a nose-up elevator command. The pendulum effect will ensure that the gondola is at the lowest point in straight flight.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;P.S.: Thanks to the hint of @kepler22b I have now discovered the &lt;a href=&quot;https://en.wikipedia.org/wiki/Keel_effect&quot; rel=&quot;noreferrer&quot;&gt;keel effect page&lt;/a&gt; on Wikipedia. It also mentions the pendulum effect and calls both the fuselage contribution to the dihedral effect. Man, if there is ever a competition for the most misleading name of an effect, this would be the winning entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pendulum is a mass mounted &lt;strong&gt;below&lt;/strong&gt; the hinge point, so it will stabilize in the down position. A flying airplane &lt;strong&gt;is not hinged&lt;/strong&gt;, so all motion is around the center of gravity. There simply is no pendulum effect in airplanes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-07-11T21:56:02.070" LastActivityDate="2018-07-11T21:56:02.070" CommentCount="19" ContentLicense="CC BY-SA 4.0" />
  <row Id="26399" PostTypeId="1" CreationDate="2016-03-25T11:00:03.940" Score="10" ViewCount="368" Body="&lt;p&gt;Many times passengers might found themselves in the lavatory, when turbulence happens. During such times, do the handlebars inside the lavatory provide adequate support to the passenger, or does it makes more sense to install some kind of seat belt?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question comes from the premise, that if a passenger is in the lavatory when sudden turbulence hits, he/she may not have such necessary aids to prevent injuries, which might lead to a claim of negligence against the airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am mostly looking at answers concerning commercial airlines.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="6979" LastEditDate="2016-03-25T16:39:53.643" LastActivityDate="2016-03-26T04:57:29.720" Title="Is it practical to install seat belts in airline lavatories?" Tags="&lt;safety&gt;&lt;airline-operations&gt;&lt;passenger&gt;" AnswerCount="2" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="26401" PostTypeId="1" CreationDate="2016-03-25T11:43:10.913" Score="8" ViewCount="693" Body="&lt;p&gt;Having travelled quite a number of times, there are times, when the cabin becomes a bit too cold, or people with certain condition get shivering quickly. In such circumstances and generally, is it possible to request for heated air in the cabin. If not the entire cabin, but atleast to specified seats, via the air flow controller on top of the head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before that, are airlines equipped to provide heated air, like in a car?&lt;/p&gt;&#xA;" OwnerUserId="14178" LastActivityDate="2016-03-25T13:50:45.140" Title="Can heated air be provided in the cabin in commercial airlines?" Tags="&lt;cabin-design&gt;&lt;temperature&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26402" PostTypeId="2" ParentId="26401" CreationDate="2016-03-25T13:41:52.077" Score="8" Body="&lt;p&gt;The fresh air vents near your head at each seat can not be adjusted for temperature individually.  Cabin temperature is controlled. Just ask a Flight Attendant to warm it up as they have a control panel to adjust cabin temperature by zone. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most modern airliners use bleed air from the engines to power two Air Conditioning Packs which circulate cooled or heated air throughout the cabin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Environmental_control_system_(aircraft)&quot; rel=&quot;noreferrer&quot;&gt;Environmental control system (aircraft)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;B777 Air Systems &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/f3KZf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/f3KZf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-25T13:50:45.140" LastActivityDate="2016-03-25T13:50:45.140" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26403" PostTypeId="2" ParentId="26397" CreationDate="2016-03-25T13:59:05.433" Score="5" Body="&lt;p&gt;The trim system on an aircraft relieves the control pressures so that the aircraft maintains an attitude without pressure on the control system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When hand-flying this is very noticeable in that you constantly have to be pushing, pulling, or turning (in the event you have aileron trim) to maintain an attitude. Notice how I don't say &quot;straight and level&quot;, you can trim an aircraft to maintain a climb/descent or other attitude as long as the trim tabs have enough authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Autopilots detect an out-of-trim condition the same way you do. They sense that there is pressure on the controls to maintain the desired attitude, and if this is over some threshold it will display a warning light for an out-of-trim condition. Some autopilots have a trim-up or trim-down light to help the pilot determine which way to trim the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a diagram from a S-Tec System 50 Autopilot found in many GA aircraft:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CHDiC.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CHDiC.png&quot; alt=&quot;System 50 AutoPilot&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;out of trim&quot; condition lights are two yellow indicators on the right side of the auto-pilot instrument.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this important? Mostly for the longevity of the equipment. The autopilot works by either physically moving the cables or actuating the hydraulic system. It uses power to run motors which cause the motors to heat up and use electrical power. By trimming the aircraft, you can reduce these forces required by the autopilot so that it isn't working so hard to control the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another good reason is that you don't want the aircraft to do something unexpected when you hit the autopilot &quot;off&quot; or &quot;disconnect&quot; switches. This is especially dangerous in IMC when you don't have a visual reference to anything. There are also conditions which can cause the autopilot to disconnect automatically, and it takes a few precious seconds to figure out what is going on before the pilot gets positive control.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-25T14:12:49.670" LastActivityDate="2016-03-25T14:12:49.670" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26404" PostTypeId="1" AcceptedAnswerId="26405" CreationDate="2016-03-25T15:43:40.867" Score="37" ViewCount="19542" Body="&lt;p&gt;Fog is a form of a cloud and it is said clouds are visible moisture.  We all know that mist (baby rain) is also moisture so I am curious when will a METAR say BR (mist) or FG (fog)?&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="595" LastEditDate="2016-03-25T18:14:52.413" LastActivityDate="2021-01-08T16:08:56.780" Title="What is the difference between mist and fog?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26405" PostTypeId="2" ParentId="26404" CreationDate="2016-03-25T15:53:13.737" Score="38" Body="&lt;p&gt;Quoting from the &lt;a href=&quot;https://www.aviationweather.gov/static/help/taf-decode.php&quot;&gt;METAR decoder&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;BR Mist (Foggy conditions with visibilities greater than 5/8 statute mile) &#xA;&#xA;FG Fog (visibility 5/8 statute mile or less)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;You may ask &quot;Why 5/8th of a statute mile?&quot;  That's because &lt;a href=&quot;http://www.wolframalpha.com/input/?i=5%2F8ths%20of%20a%20mile&quot;&gt;5/8ths of a mile is 1,006 meters&lt;/a&gt;, or about 1 kilometer.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-03-25T15:53:13.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26406" PostTypeId="2" ParentId="26404" CreationDate="2016-03-25T16:00:05.757" Score="27" Body="&lt;p&gt;The main difference between the fog and mist is their density and as a consequence, the visibility. From &lt;a href=&quot;http://www.metoffice.gov.uk/learning/fog/difference-mist-and-fog&quot; rel=&quot;noreferrer&quot;&gt;UK Met office&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... they are two distinct terms for a similar phenomenon. Visibility less than 1,000 metres we call 'fog' and obscurity with visibility greater than 1,000 metres we call 'mist'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is the same one given in FAA Aeronautical Information Manual (Page 7-1-62 in Dec 2015 Version). For visibility below 5/8 statute miles (~1000m), the term fog is used, while for values above that, mist is used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rnfCv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rnfCv.png&quot; alt=&quot;Fog and mist&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from FAA AIM, page 7-1-62&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-25T16:00:05.757" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26407" PostTypeId="1" CreationDate="2016-03-25T18:44:11.523" Score="3" ViewCount="60" Body="&lt;p&gt;I understand that the purpose of winglets is to decrease the wingtip vortexes to increase performance in climbs and cruising by redirecting the air over the wing. However on some old cessnas the winglets curve downwards. What is the reason for this?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-03-25T18:44:11.523" Title="Why do the winglets go down on some cessnas?" Tags="&lt;aerodynamics&gt;" AnswerCount="0" CommentCount="4" FavoriteCount="0" ClosedDate="2016-03-25T22:21:15.667" ContentLicense="CC BY-SA 3.0" />
  <row Id="26408" PostTypeId="2" ParentId="26399" CreationDate="2016-03-25T18:45:13.313" Score="3" Body="&lt;p&gt;Potty belts are common on business jets. They could be installed on airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;E.g.:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.embraer.com/en-US/ImprensaEventos/Press-releases/noticias/Pages/Embraer-certifica-assento-extra-para-o-jato-phenom-100.aspx&quot; rel=&quot;nofollow&quot;&gt;http://www.embraer.com/en-US/ImprensaEventos/Press-releases/noticias/Pages/Embraer-certifica-assento-extra-para-o-jato-phenom-100.aspx&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-03-25T18:45:13.313" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26409" PostTypeId="1" AcceptedAnswerId="26437" CreationDate="2016-03-25T19:29:43.690" Score="9" ViewCount="177" Body="&lt;p&gt;If the aircraft is not trimmed correctly and either the pilot or autopilot is having to use constant pressure on the elevator does this increase drag? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-26T22:47:25.417" Title="Does being out of trim affect drag?" Tags="&lt;drag&gt;&lt;trim&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26410" PostTypeId="1" AcceptedAnswerId="26433" CreationDate="2016-03-25T19:54:47.523" Score="8" ViewCount="279" Body="&lt;p&gt;If the engine on airliners has for example, an oil leak, can the oil or other substances contaminate the air on the passenger cabin? How would this situation be avoided?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-25T21:47:57.140" LastActivityDate="2016-03-26T17:42:29.857" Title="If there was an engine malfunction, could we breathe contaminated air?" Tags="&lt;airliner&gt;&lt;emergency&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26411" PostTypeId="1" CreationDate="2016-03-25T22:00:55.013" Score="2" ViewCount="621" Body="&lt;p&gt;Is there a big demand for transporting overseas for turbofan engines with nacelles like TrentXWB or GEnx by cargo airplanes ? If yes, what planes are used? &lt;/p&gt;&#xA;" OwnerUserId="14187" LastEditorUserId="12220" LastEditDate="2016-03-25T22:40:12.947" LastActivityDate="2016-03-26T00:24:00.000" Title="What cargo airplanes can transport fully assembled large turbofan engines?" Tags="&lt;engine&gt;&lt;turbofan&gt;" AnswerCount="2" CommentCount="2" ClosedDate="2016-03-27T09:53:50.760" ContentLicense="CC BY-SA 3.0" />
  <row Id="26412" PostTypeId="2" ParentId="26410" CreationDate="2016-03-25T23:07:07.877" Score="3" Body="&lt;p&gt;Jet engines on airliners take some relatively low pressure bleed air from the front stages of the compressor in order to feed compressed fresh air to the cabin and to power other items.  This air is as fresh as the outdoor air.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that when a commercial airline starts engines on the ground at an airport with a significant tailwind then the engine can ingest some of its own exhaust and therefore upon occasion as a passenger you can smell the odor of kerosene.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an engine is shut down in the air for some reason then no pressure is generated and other engines on the plane will supply the compressed air to the cabin.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastEditorUserId="13424" LastEditDate="2016-03-26T16:56:59.540" LastActivityDate="2016-03-26T16:56:59.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26413" PostTypeId="1" CreationDate="2016-03-25T23:40:58.197" Score="7" ViewCount="526" Body="&lt;p&gt;I just completed an ILS approach and went missed.  I followed the published missed approach and entered the hold.  When I entered the hold, on the MFD map a timer-like display was on top of the &quot;aircraft&quot; e.g. 00:00&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The timer display did not increase after being in the hold for about 5-10 minutes.  I even started the timer from the TMR/REF softkey on the PFD to see if it would change the display on the MFD, and it still remained at 00:00.  Does anyone know what this timer display on the MFD during a hold is?&lt;/p&gt;&#xA;" OwnerUserId="14188" LastActivityDate="2021-05-21T00:00:55.060" Title="What is the time information on the G1000 MFD map during a hold?" Tags="&lt;holding&gt;&lt;g1000&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26414" PostTypeId="2" ParentId="26411" CreationDate="2016-03-25T23:59:24.233" Score="0" Body="&lt;p&gt;I can't really answer this, but generally, there's no reason to transport fully assembled engines. They'd have to be taken apart into order to be installed anyway. The props would overbalance and overload the assembly used to raise and position the engine to properly bolt it in place. The cowling would have to be removed to allow access to connecting lines to the aircraft. Ditto the prop. Besides, in most engine changes, there's no reason to replace the cowling.&lt;/p&gt;&lt;p&gt;I once flew on a C-130 that was carrying a R-28 engine for a C-124. It wasn't even a strain.&lt;/p&gt;&#xA;" OwnerUserId="11931" LastActivityDate="2016-03-25T23:59:24.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26415" PostTypeId="2" ParentId="26411" CreationDate="2016-03-26T00:14:22.643" Score="2" Body="&lt;p&gt;Engine nacelles are part of the aircraft and not the engine. I think you're asking about fully assembled engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Oversized jet engines are usually transported by road when possible; in case air transport is required, the Antonov &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot; rel=&quot;nofollow noreferrer&quot;&gt;An-124 'Ruslan'&lt;/a&gt; is your best bet. It is the only aircraft capable of transporting engines like the Engine Alliance GP7000 and RR Trent XWB.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xfFgk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xfFgk.png&quot; alt=&quot;An 124&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.antonov.com/news/418&quot; rel=&quot;nofollow noreferrer&quot;&gt;antonov.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For smaller engines (or partially disassembled ones), other aircraft like the Boeing 747F and A330-200F are used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, &lt;a href=&quot;http://airlineinfo.com/ostpdf92/618.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this filing with US DoT&lt;/a&gt; shows the An-124 being used to transport GE GEnx engines from Rickenbacker airport to Seattle to ensure smooth production in Boeing factories.  &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="12220" LastEditDate="2016-03-26T00:24:00.000" LastActivityDate="2016-03-26T00:24:00.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26416" PostTypeId="2" ParentId="26410" CreationDate="2016-03-26T01:21:40.227" Score="8" Body="&lt;p&gt;Yes, an malfunction in a jet engine can cause contaminated air to reach the passenger cabin. It is a rare occurrence, but it does happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the most famous cases was British Midland Flight 92 on Jan 8th 1989 in Kegworth England. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Kegworth_air_disaster&quot;&gt;Kegworth air disaster&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&quot;After taking off from Heathrow at 7:52 p.m., Flight BD 092 was climbing through 28,300 feet to reach its cruising altitude of 35,000 feet when a blade detached from the fan of the port (left) CFM International CFM56 engine. While the pilots did not know the source of the problem, a pounding noise was suddenly heard, accompanied by severe vibrations. &lt;strong&gt;In addition, smoke poured into the cabin through the ventilation system and a burning smell entered the plane&lt;/strong&gt;&quot;.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to contamination from engine failures, there is a much more public debate over contamination due to perceived weaknesses in the design of the aircraft cabin air systems. These weaknesses have not been positively identified but many believe it is due to faulty engine seals and/or air conditioning packs. There are numerous reports of pilots, flight attendants, and passengers feeling ill from &quot;toxic air&quot; on aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The name &quot;Aerotoxic Syndrome&quot; is also used to describe the problem of bad air in aircraft. More information here: &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerotoxic_syndrome&quot;&gt;Aerotoxic syndrome&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a website dedicated to Toxic Cabin Air. &lt;a href=&quot;http://www.toxiccabinair.com/cms/&quot;&gt;Toxic Cabin Air&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-26T01:40:10.313" LastActivityDate="2016-03-26T01:40:10.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26419" PostTypeId="2" ParentId="23424" CreationDate="2016-03-26T04:05:32.037" Score="2" Body="&lt;p&gt;Sleep problems are a concern to the FAA. Lack of sleep or not having restful sleep contributes to fatigue, and fatigue is one of the 12, aka 'The Dirty Dozen,' leading factors for accidents, incidents and mishaps. This is a serious matter for all parties involved. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are a couple good resources: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Sleep-Disorders&quot; rel=&quot;nofollow&quot;&gt;http://www.aopa.org/Pilot-Resources/Medical/Medical-Certification-and-Conditions/Sleep-Disorders&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22&quot; rel=&quot;nofollow&quot;&gt;http://www.skybrary.aero/index.php/The_Human_Factors_%22Dirty_Dozen%22&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lack of good quality sleep not only contributes to fatigue, but it is stressful on the body and mind. It magnifies the existing stress. Tell your friend to take care of themselves first, and then they could consider working with a local AME that specializes in complex medical cases.&lt;/p&gt;&#xA;" OwnerUserId="14100" LastActivityDate="2016-03-26T04:05:32.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26420" PostTypeId="2" ParentId="26091" CreationDate="2016-03-26T04:25:23.627" Score="13" Body="&lt;p&gt;Peter's answer explains one aspect of the appearance of the engine angle being the way it is between the -200 engine angle relative to the angle of attack on the ground versus in the air and between the -200 and the -8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also the considerations of FOD (foreign object debris) entering into the engine and the account for accessories off of the engine that are concealed by the cowlings. FOD is handled very different today (using bleed air screens) than when the -200 was designed when the angle on the engine's inlet was used. As far as the accessories that are concealed under the cowlings, they are also vastly different. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another thing that drives the shape and size of the fan cowls is the bypass ratio. For the -8, the bypass ratio at takeoff is 9.0/1, so 90% of the air going through the fan goes into the bypass section. For the -200, the bypass ratio is 5.72/1, so roughly 83% of the air is bypassed. While the doesn't seem like a large difference, the geometries are significantly different. Those differences mean that the risk of FOD going through the fan versus the core are different and yield different inlet angles. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other factors that make the appearance of the overall angle being different between the two versions are going to be side slips inlet designs and just the camera angles taking the pictures. The overall angles of the engine itself may not actually be that different.&lt;/p&gt;&#xA;" OwnerUserId="14100" LastEditorUserId="19" LastEditDate="2018-01-04T11:16:09.133" LastActivityDate="2018-01-04T11:16:09.133" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26421" PostTypeId="1" AcceptedAnswerId="26435" CreationDate="2016-03-26T04:41:19.703" Score="6" ViewCount="578" Body="&lt;p&gt;Is there an acceptable treatment plan for neuropathic pain? Gabapentin is not an acceptable drug. Lyrica and Cevalla aren't approved. Is there a treatment that could even get a special issuance? &lt;/p&gt;&#xA;" OwnerUserId="14100" LastEditorUserId="12220" LastEditDate="2016-03-26T12:21:02.640" LastActivityDate="2016-03-26T18:23:35.573" Title="What are acceptable treatments for chronic pain that will not result in a loss of an FAA Medical?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26422" PostTypeId="2" ParentId="26399" CreationDate="2016-03-26T04:57:29.720" Score="4" Body="&lt;p&gt;While it may appear at first glance that a seatbelt could simply be installed, it is not a simple answer. There would actually have to be some significant certification analyses and testing done. Seat belts tend to be fabric. While those fabric lap belts are approved for the rest of the cabin, the lavatories have different certification requirements especially regarding propagation of a fire in the enclosed space. There would have to be fire certification testing done and analyses to verify that the information gained during the certification testing was applicable to all configurations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, who would want to use or even touch a lap belt that was installed in the lavatory while someone with explosive diarrhea experiences turbulence? Eww! I wouldn't want to use it as a passenger or service it as a mechanic. That is a biohazard. &lt;/p&gt;&#xA;" OwnerUserId="14100" LastActivityDate="2016-03-26T04:57:29.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26423" PostTypeId="2" ParentId="26316" CreationDate="2016-03-26T05:10:26.750" Score="0" Body="&lt;p&gt;There are two issues here: the first would be the status of the SB itself, and whether the work described in the service bulletin has been competed. The link in &lt;a href=&quot;https://aviation.stackexchange.com/a/26321/946&quot;&gt;Dave's answer&lt;/a&gt; links to an FAA website the lists all special airworthiness information bulletins, and SAIBs are not the same as SBs. This problems becomes more challenging when the OEM is not actively creating and/or maintaining the maintenance and service documentation. If the OEM still is open for business, i.e. Cessna, Robinson, Boeing, etc., they usually have a method to subscribe for updated information. The FAA may mandate an easy way to get that information, but that does not mean it is inexpensive. It is through these subscriptions that you get the latest information. For aircraft that no longer have an OEM created maintenance and service documentation, that becomes a challenge. If in doubt, refer to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-176A.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_20-176A.pdf&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="14100" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-03-26T05:54:54.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26424" PostTypeId="2" ParentId="25000" CreationDate="2016-03-26T06:44:41.953" Score="4" Body="&lt;p&gt;Like many of these answers mentioned, it depends. For instance, the 787 program did write off the airframes for the first 6 aircraft due to the extensive number of modifications that were required to those airframes. They do go to museums of strategic importance to either the manufacturer or the kick-off customer and their country. Some of these aircraft end up going into lifecycle fatigue testing or are maintained in the ownership of the manufacturer for follow-on testing that would be for upgrades or newer subsequent models. If the program is a brand new model or significant technological change to an existing model, it has to go through stability and control testing and flutter testing. That literally beats the airframe to hell. It will most likely experience an over-G loading in these tests, and therefore, cannot and should not be used to carry passengers. There would be a potential for cargo in these cases, but then there would be added maintenance costs and operating costs from being structurally modded and heavy. There aren't many that would want to purchase a 'new' aircraft that had gone through the beatings these aircraft take.&lt;/p&gt;&#xA;" OwnerUserId="14100" LastActivityDate="2016-03-26T06:44:41.953" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26425" PostTypeId="1" AcceptedAnswerId="26427" CreationDate="2016-03-26T10:07:43.850" Score="0" ViewCount="2802" Body="&lt;p&gt;How do plane tyres roll? Are they equipped with special engines like cars or are they rolling using the plane flying engines? Or can both methods be found with different constructors?&lt;/p&gt;&#xA;" OwnerUserId="14191" LastEditorUserId="595" LastEditDate="2016-03-26T10:23:11.447" LastActivityDate="2016-03-26T16:56:00.083" Title="How do plane landing-gear tyres roll before take off?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ClosedDate="2016-03-26T13:32:33.893" ContentLicense="CC BY-SA 3.0" />
  <row Id="26426" PostTypeId="2" ParentId="26425" CreationDate="2016-03-26T10:28:12.290" Score="4" Body="&lt;p&gt;During take-off roll, the aircraft tyres move due to the thrust generated by the engines (or propellers for that matter). They don't have any engines (motors) fitted inside them to help in movement. In case the engine is not producing thrust, the aircraft are towed using a tug. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-26T10:28:12.290" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26427" PostTypeId="2" ParentId="26425" CreationDate="2016-03-26T12:42:04.987" Score="5" Body="&lt;p&gt;Normally, aircraft wheels are rotating freely around their axle, unless the brakes are activated. The ground roll was a convenient time for engine warm-up in the days of piston aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, rolling on the ground using jet engines is very inefficient; fuel consumption could be reduced if the aircraft uses other means of propulsion on the ground and only starts the engines right before take-off. Therefore, electric propulsion using hub motors is actively studied. The batteries could be charged (partially) during landing, when the hub motors are switched to generator mode, and the rest of the power could be provided by the APU.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pushing back from the gate using jet engines is unwise, so a tug is used to move the aircraft to a position from which it can continue the ground roll to its take-off position. These tugs push a bar which is linked to the nose wheel of the aircraft. Towbarless (TBL) tugs scoop up the nosewheel and lift it off the ground, allowing more-secure control and faster maneuvering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p2BnA.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p2BnA.jpg&quot; alt=&quot;Conventional tug Goldhofer F110E&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conventional tug &lt;a href=&quot;http://www.goldhofer.de/en/conventional,30.html&quot; rel=&quot;noreferrer&quot;&gt;Goldhofer F110E&lt;/a&gt; (picture &lt;a href=&quot;http://www.goldhofer.de/fileadmin/bilder/galerie/TOWBAR_Galerie_110E_Galerie_01.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Fa6JN.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Fa6JN.jpg&quot; alt=&quot;Boeing 777 being pulled by Goldhofer aircraft tug&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 777 being pulled by &lt;a href=&quot;http://www.goldhofer.de/en/airport-technology,11.html&quot; rel=&quot;noreferrer&quot;&gt;Goldhofer&lt;/a&gt; TBL aircraft tug (picture &lt;a href=&quot;http://www.pixstel.com/goldhofer-aircraft-tug_picm89-8920.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). They are really hard to see when you are sitting in the cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oC4EL.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oC4EL.jpg&quot; alt=&quot;Towbarless tug&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Towbarless tug detail (picture &lt;a href=&quot;http://www.airteamimages.com/pics/93/93151_800.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-26T16:56:00.083" LastActivityDate="2016-03-26T16:56:00.083" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26428" PostTypeId="1" CreationDate="2016-03-26T13:45:31.017" Score="2" ViewCount="265" Body="&lt;p&gt;I have a healing tibia. In the worst possible case, if it does not heal fully, will this impede a future attempt to become an air traffic controller?&lt;/p&gt;&#xA;" OwnerUserId="14192" LastEditorUserId="2032" LastEditDate="2016-03-26T15:07:33.377" LastActivityDate="2016-03-26T16:02:19.273" Title="Can a person with a tibia problem become an air traffic controller?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26429" PostTypeId="2" ParentId="25043" CreationDate="2016-03-26T15:14:43.610" Score="8" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;What is the actual numerical reliability statistics of the modern, large-aircraft, commercial turbofan engines available today?&lt;/p&gt;&#xA;&lt;p&gt;e.g. How many running hours can we expect a failure after? Are there empirical or projected MTBF statistics?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Buried in &lt;a href=&quot;http://www.geaviation.com/press/ge90/ge90_20120119.html&quot; rel=&quot;noreferrer&quot;&gt;this GE press release&lt;/a&gt; is the comment that the GE90 has 'only one engine IFSD  per one million engine flight-hours'.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.icao.int/SAM/Documents/2014-EDTO/EDTO%20Module%20%204%20%E2%80%93%20Aircraft%20certification%20considerations.pdf&quot; rel=&quot;noreferrer&quot;&gt;This ICAO presentation&lt;/a&gt; has a lot more info, including these threshholds for ETOPS IFSD rates:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Propulsion system should achieve an in-flight shutdown (IFSD) rate of:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;0.05 / 1000 engine hours for EDTO 120 min&lt;/li&gt;&#xA;&lt;li&gt;0.02 / 1000 engine hours for EDTO 180 min&lt;/li&gt;&#xA;&lt;li&gt;0.01 / 1000 engine hours for EDTO beyond 180 min&lt;/li&gt;&#xA;&lt;li&gt;Rate computed based on world fleet data, on a 12-month rolling average&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This strongly implies that the reliability targets are empirical, not based on theoretical numbers.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Is there a significant difference in the failure rate between engine models or manufacturers?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Page 56 of the presentation above has some data, but IMHO not enough to draw any conclusions.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;How rapidly has engine reliability improved? Do we have a time trend of reliability numbers?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;All I can say is it's definitely improved massively, but I'm not sure where to find the info.&lt;/p&gt;&#xA;" OwnerUserId="13927" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-26T22:38:02.573" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26430" PostTypeId="2" ParentId="26428" CreationDate="2016-03-26T16:02:19.273" Score="3" Body="&lt;p&gt;In the US, an air traffic controller is required to have &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/general/classes/&quot; rel=&quot;nofollow&quot;&gt;Class-II medical&lt;/a&gt;. However, &lt;a href=&quot;https://www.leftseat.com/atc/standard2.htm&quot; rel=&quot;nofollow&quot;&gt;it is mentioned here&lt;/a&gt; that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The applicant must have no deformity of spine or limbs of sufficient&#xA;  degree to interfere with the requirements of the position of&#xA;  employment being sought. Certain limitations of range of motion may be&#xA;  acceptable for certain specific options or positions, in which case&#xA;  acceptance for employment will be noted specifically for that position&#xA;  or option only.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Other than the regulatory standpoint, reaching the top air traffic tower might be hard. There may not be elevators reaching all the way to the top. To save space, many use ladders, not even a staircase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, working as air traffic controllers does not always mean in the tower. Many radar rooms are ADA complaint and are wheel chair accessible.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-03-26T16:02:19.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26431" PostTypeId="1" AcceptedAnswerId="26434" CreationDate="2016-03-26T16:36:14.527" Score="24" ViewCount="3825" Body="&lt;p&gt;Really novice question here: if both the pilot and the aircraft are instrument-rated, why would anyone fly VFR? IFR lets one fly in a wider range of weather conditions and at night while there are no situations where VFR is allowed and IFR isn't. Or are there?&lt;/p&gt;&#xA;" OwnerUserId="14194" LastActivityDate="2016-11-19T18:03:28.373" Title="Why fly VFR at all?" Tags="&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26432" PostTypeId="2" ParentId="26431" CreationDate="2016-03-26T16:57:30.120" Score="11" Body="&lt;ol&gt;&#xA;&lt;li&gt;VFR is the basics of flight. In VFR, you learn takeoffs, landings, turns, stalls etc., with plenty to visibility to help you recover should things go wrong.&lt;/li&gt;&#xA;&lt;li&gt;IFR flight puts more workload on the pilot.&lt;/li&gt;&#xA;&lt;li&gt;You won't want to &lt;a href=&quot;https://aviation.stackexchange.com/questions/12179/aerobatics-in-firm-imc-how-would-one-do-it?lq=1&quot;&gt;fly aerobatics in IMC&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;IFR requires instruments. Instruments can fail.&lt;/li&gt;&#xA;&lt;li&gt;IFR requires more planning. You have to choose a route, tune VOR stations, join airways etc.&lt;/li&gt;&#xA;&lt;li&gt;Not all places have navigation radios on the ground. Many small airports don't have anything more than a grass strip and a few houses beside it.&lt;/li&gt;&#xA;&lt;li&gt;Sometimes you don't want to stay on predefined routes, for example in a search and rescue mission.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;It is true that most commercial operations today are carried in IFR. However there are still plenty of other flights, such as private flights to a cousin's house, sight seeing tours, aerial photography, banner towing, gliding, parachuting, crop dusting, search and rescue etc., that are conducted in good visibility and require the pilots to navigate using visual references.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-03-27T05:29:46.333" LastActivityDate="2016-03-27T05:29:46.333" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26433" PostTypeId="2" ParentId="26410" CreationDate="2016-03-26T17:42:29.857" Score="3" Body="&lt;p&gt;Yes, it is possible for contaminated air to enter the cabin. The air pressurization is provided by the &quot;packs&quot; (air conditioners), which are in turn powered by the bleed air (hot air extracted from low stages of the turbine) of the engine:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/t5oLH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t5oLH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To avoid the problem, bleed air is shut when engine trouble is confirmed or suspected. For example, the Engine Fire checklist for the Boeing 737 calls for:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;[Autothrottle]...Disengage&lt;/li&gt;&#xA;  &lt;li&gt;[Thrust lever]...Confirm...Close&lt;/li&gt;&#xA;  &lt;li&gt;[Engine start lever]...Confirm...CUTOFF&lt;/li&gt;&#xA;  &lt;li&gt;...&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;[ISOLATION VALVE]...CLOSE&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;li&gt;&lt;strong&gt;[PACK switch]...OFF&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;With one engine out, the cabin air is provided by the bleed air of the other good engine. With a dual bleed shutoff (or failure), you better get down right away.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-03-26T17:42:29.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26434" PostTypeId="2" ParentId="26431" CreationDate="2016-03-26T18:09:49.487" Score="29" Body="&lt;p&gt;(This answer is based on light aircraft in the US.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Leaving aside any scenarios where you &lt;em&gt;must&lt;/em&gt; file IFR (class A, IMC) and any where you &lt;em&gt;can't&lt;/em&gt; (pilot and/or aircraft not IFR-capable), it comes down to whether the 'overhead' and benefits of operating IFR are worth it for your particular flight. By the way, your question seems to assume that IFR is required at night, but night VFR is legal in many countries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 'overhead' of operating IFR is firstly in planning: there are different rules for fuel reserves, altitudes, airspace, alternate airports, weather minimums etc. Generally speaking you need more time and thought to prepare and file an IFR flight plan. Secondly, operating IFR potentially places a lot of restrictions on you: ATC can delay your takeoff, &lt;a href=&quot;https://aviation.stackexchange.com/q/24275/62&quot;&gt;give you vectors that take you miles out of your direct route&lt;/a&gt;, put you in a hold, require position reports, and generally keep you busy. As a pilot, you have to perform at a 'higher' - or at least different - level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For many people, that's already reason enough to file VFR if conditions allow (don't forget that in the US there's no need to talk to ATC at all on many flights). But the purpose of the flight is important too: IFR more or less assumes that you're flying from A to B on a fairly direct route. If you're training, or sightseeing, or dropping parachutists, or just flying around for the fun of it then IFR isn't really appropriate or useful. You can just &lt;a href=&quot;https://aviation.stackexchange.com/q/19265/62&quot;&gt;get flight following&lt;/a&gt; instead, which gives you the benefits of ATC keeping an eye on you, without any of the IFR rules to follow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And regarding your comment about IFR letting you fly in more weather conditions, there's a pilots' saying in the southern US (and probably many other places) that &quot;if the weather's good, file IFR; if it's bad, file VFR&quot;. The reason is that Florida and other southern states get a lot of convective activity and it's very common to have to pick your way between thunderstorms and building cumulus towers to get where you're going, or just for a more comfortable ride. By remaining in visual conditions you're able to see what's going on with the clouds and being VFR means you're more or less free to change course and altitude as needed to avoid them. If you're IFR, ATC may put you in a cloud layer where you can't see anything and vector you closer to the buildups than you'd like. VFR just gives you a lot more options in general.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, are there any scenarios where only VFR is allowed, even for IFR-capable flights? This might be different in different countries, but offhand I can't think of any in the US. IFR minimum altitudes are higher than VFR ones, so you can't fly IFR at 500' AGL, but I guess that's not really what you're thinking about. Maybe someone else will come up with something.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-03-26T18:09:49.487" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26435" PostTypeId="2" ParentId="26421" CreationDate="2016-03-26T18:23:35.573" Score="3" Body="&lt;p&gt;The only real answer here is to &lt;a href=&quot;https://www.faa.gov/pilots/amelocator/&quot; rel=&quot;nofollow&quot;&gt;consult an AME&lt;/a&gt;. I searched on the AOPA forums (members only) and the information wasn't encouraging: all current (as of 2014, which was the more recent relevant post I found) neuropathy drugs are disqualifying. AOPA's &lt;a href=&quot;http://www.aopa.org/members/databases/medical/druglist.cfm&quot; rel=&quot;nofollow&quot;&gt;list of approved drugs&lt;/a&gt; does show some approved drugs for pain relief, but it looks like it's all OTC stuff.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, the usual medical disclaimer applies here: every case is different so the above may be irrelevant to you personally; I'm not a doctor and I don't know what I'm talking about anyway; only an AME can give you meaningful information.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-26T18:23:35.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26436" PostTypeId="2" ParentId="26431" CreationDate="2016-03-26T19:11:16.953" Score="4" Body="&lt;p&gt;IFR would not be feasible for a lot of different types of recreational and professional flight activities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a majority of the flying that I used to do at one of my old jobs, I would not have been unable to get an IFR clearance had I wanted to. That notwithstanding, the routing would have been so complicated that it would have increased my workload—not to mention the controller's workload—to the extent that IFR would not have been feasible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many types of mountain flying would simply be impossible to do under IFR. The same goes for most ground proximity flying. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not necessarily recommended, a pilot could fly VFR into an active MOA, whereas an IFR flight would not be cleared into that active MOA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding weather conditions, the fact is that I could &lt;em&gt;legally&lt;/em&gt; fly in worse weather than would be allowable for many IFR operations, though to do so would—in some cases—be against company rules. It simply is not true that there are no situations in which IFR would be allowable where VFR would not. &lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-11-19T18:03:28.373" LastActivityDate="2016-11-19T18:03:28.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26437" PostTypeId="2" ParentId="26409" CreationDate="2016-03-26T22:47:25.417" Score="5" Body="&lt;p&gt;Normally not; details depend on the control system and by how much the aircraft is out of trim. The force produced by the empennage will be the same in the trimmed state and when out of trim, only the control forces are different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's examine the different possibilities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Adjustable spring (as used on some light aircraft and gliders): The elevator deflection will be identical to the trim position, so there is no difference at all.&lt;/li&gt;&#xA;&lt;li&gt;Trim or servo tab on the elevator: The tab deflection will be different, but the elevator position will be practically identical. For tab angles of less than 10° relative to the elevator there should not be any difference in drag.&lt;/li&gt;&#xA;&lt;li&gt;Adjustable stabilizer: Now the elevator deflection will be different, and depending on the trimmed state the deflection angle might cause higher airfoil drag. If the elevator deflection relative to the stabilizer is more than 10°, a slight drag increase can be expected.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If the power consumption of the autopilot is higher in the out of trim case, this might cause higher generator loads and more engine power is needed to keep it powered. But this effect should be very small.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-26T22:47:25.417" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26438" PostTypeId="1" AcceptedAnswerId="26441" CreationDate="2016-03-26T23:03:08.393" Score="5" ViewCount="749" Body="&lt;p&gt;This is going to be a no-brainer for a pilot, I am sure. I am not one, however, only an enthusiast.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario is: I am flying under the directions of ATC, into a relatively busy Class-B airport and am given a change of heading by them.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Piper N1234A, fly heading 235 ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The radio is full of communications, and I cannot seem to be able to squeeze in to confirm receipt of heading change. I assume I would start the standard-rate turn immediately, and acknowledge as soon as possible, even if I've already completed the course change?&lt;/p&gt;&#xA;" OwnerUserId="2171" LastEditorUserId="19" LastEditDate="2016-10-14T13:44:19.267" LastActivityDate="2016-10-14T15:56:32.257" Title="How quickly should a maneuver be started when ATC gives new heading?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26439" PostTypeId="1" AcceptedAnswerId="26446" CreationDate="2016-03-26T23:07:37.920" Score="16" ViewCount="7543" Body="&lt;p&gt;Almost every aspect of flight seems to be affected by the speed of sound, somewhat in the same way that nearly everything in physics is determined by the speed of light.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously it's not exactly the same - it &lt;em&gt;is&lt;/em&gt; possible to travel faster than the speed of sound, unlike the speed of light - but still, what happens below the speed of sound is quite different from what happens above the speed of sound, while the region close to the speed of sound seems to be a mysterious transition zone.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This isn't just limited to aerodynamics, but also for example to the way the fuel/air mixture burns in a jet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, &lt;em&gt;why is the speed of sound so significant&lt;/em&gt; for aerodynamics and aircraft design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I presume that it is something to do with a limit on how fast information about the movement (or pressure changes) of air molecules (i.e cause and effect involving air molecules) can travel through a medium of those molecules, and that &quot;speed of sound&quot; is shorthand for that speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These movements of air molecules presumably also might be in a form that we wouldn't ever actually hear (frequency too low, frequency too high) or indeed that we wouldn't ever experience as a sound (a single pulse rather than a vibration); in this case &quot;speed of sound&quot; seems to be a rather misleading way of describing it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume that there are analogous issues around the speed of information of pressure changes in water, so that hydrodynamics has to deal with them too. I imagine that because is much less compressible than air, that the speed would be much higher, so perhaps less likely to trouble hydrodynamic designers and engineers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think my high-school physics seems to be more or less enough to deal with these concepts, but the language around &lt;em&gt;speed of sound&lt;/em&gt; does seem to hide away some of the key ideas, and leads my intuitive grasp in the wrong directions.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="12720" LastEditDate="2016-03-26T23:18:11.510" LastActivityDate="2016-07-13T19:39:24.173" Title="What is the significance of the speed of sound to aerodynamics and aircraft design?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-physics&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26441" PostTypeId="2" ParentId="26438" CreationDate="2016-03-27T00:07:51.573" Score="8" Body="&lt;p&gt;You are correct, you should turn to the assigned heading immediately unless you aren't sure of the instruction (was that 100 assignment a heading or a speed?).   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When ATC gives you a change, it is based on a continuously changing environment and they want you comply right away, as long as it was clear. Usually, doing the wrong thing is worse than doing nothing at all. &lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-03-27T00:07:51.573" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26442" PostTypeId="2" ParentId="26439" CreationDate="2016-03-27T01:16:17.880" Score="10" Body="&lt;p&gt;You're correct that the speed of sound is important because it has something to do with how 'information' is transmitted through the gas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 'speed' of sound is actually the speed of transmission of a (small) disturbance through the medium. Air is a compressible medium, in general. When there is an infinestimal pressure change generated at some point of the flow due to some disturbance (say, an airfoil moving), this will be propogated throughout the air as a pressure wave at the speed of sound. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disturbances are propogated in the air due to collisions involving (randomly moving) molecules. Due to this, the air molecules in the path of the disturbance 'knows' that there is something coming on their way and try to get out. Consider the following image of an airfoil in a smoke tunnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yEZR0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yEZR0.jpg&quot; alt=&quot;airfoil smoke&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://forums.x-plane.org/uploads/monthly_04_2015/post-1379-0-33469900-1430161721.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;forums.x-plane.org&lt;/a&gt;; credited to Alexander Lippisch&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here, you can see that the air (made visible through smoke) has already 'moved' out of way of the airfoil before coming into physical contact with it; this is because of the disturbance, which was propogated through the air at the speed of sound. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, if the flow velocity exceeds the speed of propogation of these disturbances, they will 'pile up' to form strong (pressure) waves, which we call shock waves. The following image shows a model of the X-15 in a wind tunnel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BwLc5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BwLc5.jpg&quot; alt=&quot;X-15&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By NASA - Great Images in NASA Description, Public Domain, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=6450008&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=6450008&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disturbances are still being propogated; but the flow velocity is greater than that- the result is that the molecules have no way of 'knowing' that there is an object is on the way and pile up over it.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="946" LastEditDate="2016-03-27T03:46:44.913" LastActivityDate="2016-03-27T03:46:44.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26443" PostTypeId="1" CreationDate="2016-03-27T02:18:32.307" Score="30" ViewCount="843" Body="&lt;p&gt;I own a grass airstrip that was registered for me by a good friend.  I want to sell my land and the guy that registered it is dying and can't help me.  What do I need to do to have this airstrip closed?&lt;/p&gt;&#xA;" OwnerUserId="14201" LastEditorUserId="12220" LastEditDate="2016-03-27T20:42:32.910" LastActivityDate="2016-03-27T20:42:32.910" Title="What is the proper air strip closure procedure with the FAA?" Tags="&lt;usa&gt;&lt;faa&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26444" PostTypeId="2" ParentId="26443" CreationDate="2016-03-27T03:31:54.143" Score="27" Body="&lt;p&gt;It looks to me like you need to file &lt;a href=&quot;http://aeronav.faa.gov/content/aeronav/Form7480_1.pdf&quot;&gt;FAA Form 7480-1&lt;/a&gt;, Notice of Landing Area Proposal.  There is a checkbox for &quot;Deactivation or Abandonment&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The form explains that you have to give 90 days advance notice.  So you shouldn't make any changes until 90 days after filing the form.  This presumably gives them time to update charts, so that pilots know the airstrip is no longer usable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The form has the address and phone number for your FAA regional office, who might be able to help if you have questions about how to complete the form.&lt;/p&gt;&#xA;" OwnerUserId="2546" LastActivityDate="2016-03-27T03:31:54.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26445" PostTypeId="1" CreationDate="2016-03-27T04:52:01.060" Score="9" ViewCount="222" Body="&lt;p&gt;A typical IFR cleared route is like, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;KABC VOR1 V12 VOR2 V23 VOR3 V34 VOR4 KXYZ&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Suppose the verbal ATC clearance is &quot;N7890, you are cleared to KXYZ airport, KABC.ZYBUD departure, radar vector VOR1, V12 VOR2 V23 VOR3 V34 VOR4 then direct, climb and maintain 3000, expected 5000 5 min after departure, departure frequency is 123.45, squawk 4321&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While you are en-route on V12, ATC says &quot;cleared direct to VOR3&quot;. Does this new clearance change the clearance limit from KXYZ to VOR3? If no further clearance is issued while approaching VOR3, should we hold at VOR3 or continued with the cleared route firstly obtained?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;POST EDIT: &#xA;The context is within US.&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-03-31T07:09:16.250" LastActivityDate="2016-03-31T07:09:16.250" Title="Does an amended shortcut clearance change the clearance limit?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;ifr-navigation&gt;&lt;holding&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26446" PostTypeId="2" ParentId="26439" CreationDate="2016-03-27T07:41:46.693" Score="16" Body="&lt;p&gt;Your question shows that you know that the speed of sound is the speed of small pressure changes in a fluid, and moving faster than that will give the fluid ahead no warning of an approaching disturbance. I will, therefore, dig a little deeper in my answer, fully knowing that I can only scratch the surface. I encourage you to ask more specifically if one topic piques your interest but is not sufficiently explained.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Short answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The speed of sound is significant in aircraft design mainly in:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Splitting the flight regimes into two areas with markedly different flow behavior,&lt;/li&gt;&#xA;&lt;li&gt;helping to convert a geometry for compressible flow to one which can be calculated by simpler, incompressible methods,&lt;/li&gt;&#xA;&lt;li&gt;limiting the maximum practical flight speed for efficient air travel and&lt;/li&gt;&#xA;&lt;li&gt;giving the designer hints how to push this boundary up.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the combustion of gasses the speed of sound is of less significance than the &lt;a href=&quot;https://en.wikipedia.org/wiki/Flame_speed&quot; rel=&quot;nofollow noreferrer&quot;&gt;speed at which a flame advances&lt;/a&gt;. This is &lt;a href=&quot;http://engine.princeton.edu/download/ju-digital-publication/2004-nonlinear-science-flame-front-Ju-Lee.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more complex&lt;/a&gt; (PDF!) and depends on the turbulence level, mixing ratio, temperature and the activation energy for the combustion reaction to start.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Explanation&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To explain the influence of the speed of sound let me look at the molecular level: Air is a collection of molecules which zip around constantly, bumping into each other frequently. We express this with macroscopic parameters:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The intensity of the collisions is measured as pressure,&lt;/li&gt;&#xA;&lt;li&gt;the number of molecules per volume is measured as density, and&lt;/li&gt;&#xA;&lt;li&gt;the speed of the molecular movement is measured as temperature.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At rest, the frequency and intensity of these collisions is the same in all directions. If something moves through the gas at a speed far below the speed of sound, the collisions are still roughly of the same intensity all around. The local intensity may vary, but the molecules will stay equally distributed over the volume. This means that the disturbance will cause a change in pressure, but density will be unaffected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Similarity methods&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moving faster, the disturbance will cause more intense collisions in the direction of movement and will start to push the molecules together: Now it will also cause weak density changes, and those grow with the square of of its speed. To regain an equal distribution over space, the molecules will now move sideways (and up and down), and the pressure changes will reach farther out to the sides. When you compare the pressure fields at different speeds, the &quot;faster&quot; field will look like one made by a more narrow disturbance at lower speed. This effect is captured by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Prandtl%E2%80%93Glauert_transformation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Prandtl-Glauert factor&lt;/a&gt; $(1-Mach)^2$. Scaling the Y- and Z-coordinates of an aircraft geometry (where X is in flight direction) with this factor will result in a geometry which can be calculated with incompressible methods.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the speed of sound this factor has a singularity, so its application should be restricted to speeds below Mach 0.7. Above Mach 1 a similar transformation can be applied, now using the &lt;a href=&quot;https://en.wikipedia.org/wiki/Jakob_Ackeret&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ackeret&lt;/a&gt; factor $(Mach-1)^2$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Convergent and divergent flow&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ratio of density changes to pressure changes continues to increase such that in supersonic flow the density changes become dominant. This shows when looking at the flow in an expanding or contracting duct:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Subsonic flow in an expanding duct will slow down to preserve density and will accelerate in a contracting duct.&lt;/li&gt;&#xA;&lt;li&gt;Supersonic flow in an expanding duct will accelerate further, reducing density and pressure, and decelerate in a contracting duct.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This different behavior is used when accelerating the compressed gasses flowing from an aircraft turbine: First the nozzle diameter is reduced until the gas accelerates to the speed of sound. To accelerate the gas further, now the diameter has to increase again in flow direction. The result is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9653/why-are-adjustable-area-jet-engine-nozzles-mostly-limited-to-military-use/9666#9666&quot;&gt;convergent-divergent nozzle&lt;/a&gt;, a typical part of supersonic jet engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Wave drag&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now picture the aircraft in slow motion from the side as it slices through the air at supersonic speed: Since pressure increases while the aircraft body expands and decreases once it contracts, you will have two drag components in supersonic flow which do not exist in subsonic flow: Forward facing parts experience higher pressure and rearward-facing parts experience suction. This effect is called wave drag and makes supersonic flight inherently less efficient that subsonic flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Transsonic design&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same effect also affects the pressure field around an aircraft which is moving close to the speed of sound. Its movement displaces air and has an effect similar to a contracting duct, accelerating the flow in its vicinity as long as the aircraft grows thicker in flow direction, and decelerating it again over its rear half where it contracts. Once this local flow reaches the speed of sound, it will accelerate further while the aircraft contour contracts, leading to a supersonic pocket of air which will not slow down. It does so eventually, collapsing in a local shock which can cause &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=7%7C0.1508#5055&quot;&gt;flow separation&lt;/a&gt; and high local drag. Even worse, this separation will affect the whole pressure field and reduce the speed increase, which opens a feedback loop which will make the shock fluctuate. This oscillating shock can excite vibrations, render control surfaces ineffective and can incite flutter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To reduce the local speed increase the surfaces of airplanes can be swept so the flight speed can be increased without running into the aforementioned transsonic effects. Also, sweep will smear out the sonic effects when accelerating through Mach 1, so the drag peak around Mach 1 can be greatly reduced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Around Mach 1 it is important to limit the rate at which the aircraft's body expands or contracts over the direction of flight, and the wider-ranging nature of pressure changes allows the designer to expand one part of the aircraft to compensate for the local contraction at a different part when both are at the same position relative to the direction of flight. The consequence of this is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/7451/what-is-the-area-rule&quot;&gt;area rule&lt;/a&gt; which shows in &lt;a href=&quot;https://aviation.stackexchange.com/questions/16296/confusion-on-area-rule-application-on-airliners-like-the-a380&quot;&gt;coke-bottle fuselages&lt;/a&gt; or big &lt;a href=&quot;https://aviation.stackexchange.com/questions/16296/confusion-on-area-rule-application-on-airliners-like-the-a380/16301?s=1%7C0.3671#16301&quot;&gt;flap track fairings&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-07-13T19:39:24.173" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26453" PostTypeId="2" ParentId="26445" CreationDate="2016-03-27T16:43:53.390" Score="2" Body="&lt;p&gt;It doesn't change your clearance limit. If it were to change your clearance limit, he would have issued you a new clearance Instead of &quot;cleared direct ...&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually it goes something like this: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;N123, I have an amended clearance for you. Advise ready to copy&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Approach ready to copy&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;N123, you are cleared present position to ... &quot;&#xA; And then CRAFT. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-03-27T20:54:13.683" LastActivityDate="2016-03-27T20:54:13.683" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26456" PostTypeId="2" ParentId="26445" CreationDate="2016-03-27T18:07:27.197" Score="6" Body="&lt;p&gt;I assume that this question is about the US, based on your examples. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, it doesn't change the clearance limit. For some reason I could only find the documentation in the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC orders&lt;/a&gt;, not the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot;&gt;AIM&lt;/a&gt;. Section 4-2-5 of the orders says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;Issue a clearance “direct” to a point on the previously issued route.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;PHRASEOLOGY&lt;/strong&gt;−&lt;br&gt;&#xA;  CLEARED DIRECT (fix,waypoint).&lt;br&gt;&#xA;  Or&lt;br&gt;&#xA;  CLEARED DIRECT (destination) AIRPORT.&lt;/em&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;&lt;em&gt;NOTE&lt;/strong&gt;− Clearances authorizing “direct” to a&#xA;  point on a previously issued route do not require the phrase “rest of&#xA;  route unchanged.” However, it must be understood where the previously&#xA;  cleared route is resumed. When necessary, “rest of route unchanged”&#xA;  may be used to clarify routing.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the clearance limit changes, the controller will usually give you a completely new clearance to copy.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-03-27T18:07:27.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26457" PostTypeId="1" AcceptedAnswerId="26461" CreationDate="2016-03-27T19:02:04.857" Score="7" ViewCount="2023" Body="&lt;p&gt;I noticed in &lt;a href=&quot;https://www.youtube.com/watch?v=GdWWr4O2P04&quot; rel=&quot;nofollow noreferrer&quot;&gt;this recent video&lt;/a&gt; that some of the passengers are not wearing their seat belts. I realize this is not a typical commercial flight, but is it advisable to wear seat belts when a 747 or similar aircraft is flying so close to the ground, (apparently) during a final approach? Or are the safety precautions here so thorough that it's not actually necessary in this case?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/k6Vc7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/k6Vc7.png&quot; alt=&quot;nice view! (crop 2)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JXIa0.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JXIa0.png&quot; alt=&quot;nice view! (crop 1)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PA43S.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PA43S.png&quot; alt=&quot;nice view!&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14213" LastActivityDate="2016-03-28T00:53:55.470" Title="Is it always advisable for passengers to wear seat belts when a 747 is on final approach?" Tags="&lt;safety&gt;&lt;military&gt;&lt;approach&gt;" AnswerCount="3" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="26458" PostTypeId="1" CreationDate="2016-03-27T19:51:28.520" Score="9" ViewCount="6224" Body="&lt;p&gt;I would like to ask about the function of the lower vertical fin in Mig 23 .&lt;a href=&quot;https://i.stack.imgur.com/kSgMw.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kSgMw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14215" LastEditorUserId="12623" LastEditDate="2016-03-27T19:58:57.010" LastActivityDate="2019-10-02T11:23:32.567" Title="What is the function of the lower vertical fin on a MIG-23?" Tags="&lt;aircraft-design&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26459" PostTypeId="2" ParentId="26457" CreationDate="2016-03-27T20:12:18.500" Score="13" Body="&lt;p&gt;Yes, it is always advisable for passengers to wear the provided safety belts in all phases of flight. This is especially true for aircraft on takeoff, landing, in low level flight, or in any other flight regimes that are especially prone to turbulence or other risk exposure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A large, heavy aircraft—such as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot;&gt;B747&lt;/a&gt;—will be less affected by wake or mechanical turbulence than would a smaller aircraft—such as a &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_CRJ200#CRJ200&quot;&gt;CRJ200&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/Cessna_172&quot;&gt;C172&lt;/a&gt;. However, even large, heavy aircraft can be subjected to severe turbulence that could result in injury or death if passengers are not restrained by appropriate safety belts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, for flights conducted under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=20524ff5a58bd9263808557ecf34715e&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1311&quot;&gt;14 CFR 121&lt;/a&gt;—which I am confident is a majority of the US operated passenger flights involving the B747 (though not, obviously, Air Force One pictured in the question above)—passengers are generally required to:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;occupy an approved seat or berth with a separate safety belt properly secured about him or her during movement on the surface, &lt;strong&gt;takeoff&lt;/strong&gt;, and &lt;strong&gt;landing&lt;/strong&gt;&lt;br&gt;&#xA;  &lt;em&gt;&lt;sub&gt;Excerpted from 14 CFR 121.311 (b)&lt;/sub&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-03-28T00:53:55.470" LastActivityDate="2016-03-28T00:53:55.470" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26460" PostTypeId="2" ParentId="26458" CreationDate="2016-03-27T20:19:50.367" Score="2" Body="&lt;p&gt;That piece of tail under the belly made it easier for the MiG-23 to be stabilised in high speed conditions. That part would be folded away for ground operations if you are also curious about that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airvectors.net/avmig23_1.html&quot; rel=&quot;nofollow&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-03-27T20:19:50.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26461" PostTypeId="2" ParentId="26457" CreationDate="2016-03-27T21:05:19.917" Score="7" Body="&lt;p&gt;It is, of course, advisable to wear your seat belt, yes. However, there appears to be somewhat of a tradition of not always wearing seat belts on Air Force One:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stanley B. Greenberg, &lt;em&gt;Dispatches from the War Room: In the Trenches with Five Extraordinary Leaders&lt;/em&gt; (&lt;a href=&quot;https://books.google.com/books?id=rGTwXgpDUXUC&amp;amp;pg=PA98&amp;amp;lpg=PA98&amp;amp;dq=air%20force%20one%20seat%20belts&amp;amp;source=bl&amp;amp;ots=COpztRELQP&amp;amp;sig=yPUJNu9msgO1ABaFN1FP50IXJ0w&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwirsOnS3uHLAhUS9WMKHRjaBCg4ChDoAQhUMAk#v=onepage&amp;amp;q=air%20force%20one%20seat%20belts&amp;amp;f=false&quot;&gt;Google Books&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Nobody wears seat belts and everyone uses their cell phones while the&#xA;  plane is taking off.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Presumably the crew would provide a special warning if they expected a rough ride.&lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2016-03-27T21:05:19.917" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26462" PostTypeId="1" AcceptedAnswerId="26468" CreationDate="2016-03-27T21:14:28.197" Score="5" ViewCount="1551" Body="&lt;p&gt;I'm aware of both &lt;a href=&quot;http://www.wsdot.wa.gov/aviation/Registration/Program.htm&quot; rel=&quot;nofollow&quot;&gt;Washington&lt;/a&gt; and &lt;a href=&quot;http://www.oregon.gov/aviation/pages/aircraftreg.aspx&quot; rel=&quot;nofollow&quot;&gt;Oregon&lt;/a&gt; requiring, by law, registration of aircraft and pilots who are based in the state. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this something &lt;em&gt;every&lt;/em&gt; state does? Do states enforce it?&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2016-03-27T22:26:09.453" LastActivityDate="2018-02-10T02:42:02.720" Title="Does every state in the US require aircraft and pilot registration?" Tags="&lt;faa-regulations&gt;&lt;usa&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="26463" PostTypeId="1" AcceptedAnswerId="26465" CreationDate="2016-03-27T22:27:31.737" Score="4" ViewCount="4024" Body="&lt;p&gt;NACA airfoils are not used anymore except on some aircraft. So which type of airfoil does the 737 use? Which company designs it and builds it?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-03-28T12:03:44.937" LastActivityDate="2019-08-14T07:26:09.577" Title="Which type of airfoil does the 737 use?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;boeing-737&gt;&lt;airfoil&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26464" PostTypeId="2" ParentId="26458" CreationDate="2016-03-27T23:16:34.673" Score="5" Body="&lt;p&gt;It is called called a ventral fin and is used to provide improved stability. A number of combat aircraft (like F-14, F-8, for example) have them. the image below shows the ventral fin in F-8.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YVTzJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YVTzJ.jpg&quot; alt=&quot;F-8 ventral fin&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-024-DFRC.html&quot; rel=&quot;noreferrer&quot;&gt;nasa.gov&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding a ventral fin helps in increasing directional stability (especially at supersonic speeds) and reduces yaw induced roll (as the roll contribution of vertical fin is reduced in a sideslip). This improves the handling qualities. Another advantage is that they retain their effectiveness at high angles of attack, while the vertical fin may be blanked by the main wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ventral fins in Mig 23 were quite big, which necessiated folding them when landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jGP2Y.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jGP2Y.jpg&quot; alt=&quot;Mig 23&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;MiG-23 with wing flaps lowered, landing gear deployed, and ventral fin folded aside as it approaches to land&lt;/em&gt;; image from &lt;a href=&quot;http://www.aerospaceweb.org/aircraft/fighter/mig23/pics03.shtml&quot; rel=&quot;noreferrer&quot;&gt;aerospaceweb.org&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is not limited to Mig-23; Vought XF8U-3 'Super Crusader' also had quite large ventral fins, which required folding.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-27T23:16:34.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26465" PostTypeId="2" ParentId="26463" CreationDate="2016-03-27T23:31:41.500" Score="9" Body="&lt;p&gt;Boeing designs its own airfoils for its aricraft. According to &lt;a href=&quot;http://m-selig.ae.illinois.edu/ads/aircraft.html&quot;&gt;this site,&lt;/a&gt; the following airfoils are used in 737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737-100: Wing root- BAC 449/450/451; Wing tip- BAC 442&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737-200: Wing root- BAC 449/450/451; Wing tip- BAC 442&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737-300: Wing root- BAC 449/450/451; Wing tip- BAC 442 mod&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737-400: Wing root- BAC 449/450/451; Wing tip- BAC 442 mod&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 737-500: Wing root- BAC 449/450/451; Wing tip- BAC 442 mod&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 737 wings are manufactured at the Boeing plant in Renton, Washington.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-03-27T23:31:41.500" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26466" PostTypeId="2" ParentId="26457" CreationDate="2016-03-28T00:39:47.903" Score="2" Body="&lt;p&gt;Don't worry about what Obama does in particular . It's always advised to wear seat belt whether you are in Boeing 747 or other small planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to this &lt;a href=&quot;http://www.telegraph.co.uk/travel/news/Will-wearing-a-seatbelt-on-a-plane-save-your-life/&quot; rel=&quot;nofollow&quot;&gt;Telegraph.co.uk&lt;/a&gt; article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;Seat belts are required and designed to ensure passenger safety and reduce the risk of injury, particularly during deceleration, turbulence and unplanned or difficult to predict events.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And later on in the same article:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Last year, severe turbulence caused three EasyJet crew members to “hit&#xA;  the ceiling” over Italy, according to a passenger eye-witness, with&#xA;  one sustaining a hip injury. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Now all that can be said is if you don't want to be next victim wear the seatbelts.&lt;/p&gt;&#xA;" OwnerUserId="14219" LastEditorUserId="12720" LastEditDate="2016-03-28T00:51:51.690" LastActivityDate="2016-03-28T00:51:51.690" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26467" PostTypeId="1" AcceptedAnswerId="26469" CreationDate="2016-03-28T02:20:36.563" Score="10" ViewCount="21882" Body="&lt;p&gt;I am reading about aircraft maneuvering and the end of section check contains this question: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During a turn, if you reduce the airspeed and maintain the angle of bank, the result is a _____________ rate of turn. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The correct answer is &quot;higher&quot; which is confusing me. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If I reduce the airspeed, won't it take longer to complete the turn, thus &quot;lower&quot; rate of turn? &lt;/li&gt;&#xA;&lt;li&gt;I can understand that the turn might be smoother and more coordinated if I reduce the airspeed, but how can the rate of turn be higher? &lt;/li&gt;&#xA;&lt;li&gt;What am I missing here?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13883" LastEditorUserId="5517" LastEditDate="2016-03-28T14:06:57.017" LastActivityDate="2018-11-25T17:08:57.120" Title="What is the relation between airspeed and rate of turn?" Tags="&lt;airspeed&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26468" PostTypeId="2" ParentId="26462" CreationDate="2016-03-28T02:38:16.320" Score="5" Body="&lt;p&gt;&lt;strong&gt;No.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It varies from state to state. &lt;a href=&quot;https://www.dot.ny.gov/divisions/operating/opdm/aviation/faqs&quot;&gt;New York&lt;/a&gt;, for example, requires tax payment but no aircraft or pilot registration. &lt;a href=&quot;http://www.state.nj.us/transportation/airwater/aviation/faqs.shtm&quot;&gt;New Jersey&lt;/a&gt; doesn't require any registration and didn't mention any taxes. In &lt;a href=&quot;http://www.delreg.com/air.cfm&quot;&gt;Delaware&lt;/a&gt;, registration is required but taxes can be waived if you register your aircraft under your corporate, instead of your own name. &lt;a href=&quot;http://www.iowadot.gov/aviation/aircraftregistration/registration.aspx&quot;&gt;Iowa&lt;/a&gt; requires registration and so does &lt;a href=&quot;https://www.dot.state.oh.us/Divisions/Operations/Aviation/Pages/AircraftRegistration.aspx&quot;&gt;Ohio&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find a single resource which lists all states and their aircraft and pilot registration requirements. FAA does not have this information, probably because FAA does not care about state regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can create a Wiki on this topic here.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-03-28T02:38:16.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26469" PostTypeId="2" ParentId="26467" CreationDate="2016-03-28T03:03:46.273" Score="13" Body="&lt;p&gt;Independent of airspeed, angle of bank gives you the &quot;G&quot; force in a level coordinated turn. A 60 degree bank = 2 G's, at any speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At low speed, a given G force will give you a greater heading change than it would at a high speed. Driving your car at 10 mph you can complete a U-turn, 180 degrees of heading change, in a couple seconds without pinning passengers against the door, but at highway speeds, even a hard turn that does impose big side-loads will take much longer to give you that much heading change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related to all this is turn &lt;em&gt;radius&lt;/em&gt;: at low speed, your turn radius for any given loading (bank angle) is smaller than it would be at a higher speed with that same loading/bank angle. Thus, even though you're going slower, you have less distance (circumference of the circle) to cover, and so you are able to complete the circle (or one 360th of it) more quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;((For the pedantic ones, everything here assumes level, coordinated turns. Change those assumptions enough, things can be different, but those aren't particularly instructive cases until the base case is understood.))&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-03-28T03:03:46.273" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26470" PostTypeId="2" ParentId="26467" CreationDate="2016-03-28T03:47:17.430" Score="8" Body="&lt;p&gt;The rate of turn is inversely proportional to the (True) airspeed. For an aircraft in a level, coordinated turn, the rate of turn is given by&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\mathrm{Rate\ of\ turn} = \frac{1091 \tan\theta}{V}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Rate of turn is in degrees per second,&lt;/li&gt;&#xA;&lt;li&gt;$\theta$ is the bank angle in degrees, and&lt;/li&gt;&#xA;&lt;li&gt;$V$ is the TAS in knots.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, as the airspeed decreases, the rate of turn increases and vice versa—as long as the angle of bank is kept constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tfu6K.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tfu6K.jpg&quot; alt=&quot;Rate of turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Image from &lt;a href=&quot;http://www.cfinotebook.net/graphics/maneuvers-and-procedures/airborne/Rate-And-Radius-Of-Turn.jpg&quot; rel=&quot;noreferrer&quot;&gt;cfinotebook.net&lt;/a&gt;&lt;/strong&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an aircraft in a coordinated turn (i.e., no skidding or slipping), the vertical component of lift is equal to the weight, while the horizontal component is equal to the centrifugal force. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TR22B.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TR22B.jpg&quot; alt=&quot;Forces in a turn&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Forces in a turn, image from Instrument Flying Handbook&lt;/strong&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the aircraft turns, if the airspeed increases with the bank angle held constant, the radius of turn increases with the square of the speed ($r = \frac{V^{2}}{11.26 \tan\theta}\ \mathrm{ft}$). Hence, the distance traveled during the turn increases as the square of the speed. Even though the aircraft is flying faster, the distance to be flown increases faster than the speed. As a result, the time taken to complete the turn is increased and the turn rate decreases.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="2143" LastEditDate="2016-03-28T15:20:14.477" LastActivityDate="2016-03-28T15:20:14.477" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26471" PostTypeId="1" CreationDate="2016-03-28T05:54:40.817" Score="15" ViewCount="1474" Body="&lt;p&gt;Tom is flying a C172S/G on &lt;a href=&quot;http://flightaware.com/resources/airport/SNS/IAP/ILS+RWY+31/pdf&quot; rel=&quot;noreferrer&quot;&gt;ILS RWY 31 approach to KSNS&lt;/a&gt;. He just established on the localizer at 6000, from the SNS-22 DME Arc. He obtained weather from ATIS, wind 240@20G23, ceiling OVC006, visibility 1 1/2 SM. The wind favors RWY 26 but he notice there is no published circling minimum associated with his current ILS RWY 31 approach. He checked other approaches and found &lt;a href=&quot;http://flightaware.com/resources/airport/SNS/IAP/RNAV+(GPS)+Y+RWY+31/pdf&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) Y RWY 31 @ KSNS&lt;/a&gt; has a published circling minimum of 500-1. He thinks since the two approaches are for the same runway and final leg should be similar, he may use the RNAV 500-1 circling minimum and to land on RWY 26. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;X-Wind quick notes: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wind angle for RWY 31 is 70˚. &lt;/li&gt;&#xA;&lt;li&gt;Crosswind component for Landing on RWY 31 (18~22 knots)&lt;/li&gt;&#xA;&lt;li&gt;Maximum demonstrated crosswind for C172S is 15 knots&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this case, what should he do? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A) Continue the ILS RWY 31 straight-in approach and land on RWY 31&lt;/li&gt;&#xA;&lt;li&gt;B) Advise tower circle south to land on RWY 26. Start to circle upon reaching 500. &lt;/li&gt;&#xA;&lt;li&gt;C) Change to &lt;a href=&quot;http://flightaware.com/resources/airport/SNS/IAP/RNAV+(GPS)+Y+RWY+31/pdf&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) Y RWY 31 @ KSNS&lt;/a&gt; (approach without vertical guidance), re-intercept final approach course (WIGGL-IVUVY leg) and circling to RWY 26.&lt;/li&gt;&#xA;&lt;li&gt;C*) Change to &lt;a href=&quot;http://flightaware.com/resources/airport/SNS/IAP/LOC_DME+RWY+31/pdf&quot; rel=&quot;noreferrer&quot;&gt;LOC/DME RWY 31 @KSNS&lt;/a&gt; (load a new approach) and circle at 560 to RWY 26&lt;/li&gt;&#xA;&lt;li&gt;D) Once he has the airport in sight, cancel IFR and advise tower enter left base for RWY 26&lt;/li&gt;&#xA;&lt;li&gt;E) Low-approach flying over RWY 31 until reaching 31-26 intersection, turn left and land on RWY 26. &lt;/li&gt;&#xA;&lt;li&gt;F) Others, your suggestions.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dcEP2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dcEP2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1IT5R.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1IT5R.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="69" LastEditDate="2016-03-29T17:55:15.503" LastActivityDate="2016-08-21T19:03:40.083" Title="Can I circle to a different runway if cleared for an instrument approach without circling minimums?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;&lt;iaps&gt;&lt;non-precision-approach&gt;&lt;circling-approach&gt;" AnswerCount="4" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26472" PostTypeId="2" ParentId="26471" CreationDate="2016-03-28T06:04:06.040" Score="13" Body="&lt;p&gt;&lt;strong&gt;The only minimums that apply to &lt;em&gt;any approach&lt;/em&gt; are those printed on the plate.&lt;/strong&gt; Doing anything else is being a test pilot. Minimums are charted based on obstacle clearance, descent gradient, distance from the airport, and a variety of other factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The appropriate course of action is to either:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;land straight in on 31 and attempt to deal with the crosswind. This would be preferred, in my opinion.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;go missed&lt;/em&gt; and pick up the GPS Y 31 approach and circle to 25. You can't switch approaches once you're cleared. Given the ~1 mile visibility and low ceilings, this would not be ideal.&lt;/li&gt;&#xA;&lt;li&gt;divert to your alternate if neither of those works. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Choosing a build-your-own circle with 600' ceilings is reckless - certainly more so than landing with a ~15-20 knot crosswind. There's no guarantee that you'll remain clear of any surface obstacles.&lt;/p&gt;&#xA;" OwnerUserId="39" LastEditorUserId="39" LastEditDate="2016-03-28T12:42:56.077" LastActivityDate="2016-03-28T12:42:56.077" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26473" PostTypeId="1" AcceptedAnswerId="26475" CreationDate="2016-03-28T06:25:20.137" Score="29" ViewCount="4105" Body="&lt;p&gt;Say a seaplane has ditched onto ocean or a very large lake due to engine failure. Is it possible to sail the plane to the shore using wind alone, similar to sailing a boat?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-03-28T07:52:03.150" LastActivityDate="2016-03-29T06:35:30.317" Title="Is it possible to sail a seaplane?" Tags="&lt;flight-controls&gt;&lt;seaplane&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26474" PostTypeId="2" ParentId="26458" CreationDate="2016-03-28T06:41:23.903" Score="14" Body="&lt;p&gt;Directional stability at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air above the aircraft is less dense at supersonic speed, and elasticity reduces the effectivity of the fin - it bends and twists from the air loads. Conversely, the lower fin operates in denser air and creates more side force per area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the lower fin shifts the aerodynamic center of the empennage downwards, which is improving the handling characteristics. Adding area below the centerline helps to reduce the roll contribution of the vertical tail in a sideslip, which improves handling characteristics (more directional stability AND lower yaw-induced roll).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as the vertical tail surface sits above the centerline (more precisely the longitudinal axis of inertia - for now we can assume both fall together), any side force will also create a rolling moment.  This is undesirable because now a yaw command will not only create the intended yawing moment, but also a rolling moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to yaw in order to turn, the vertical tail above the centerline will even roll the aircraft in the wrong direction, so you need more coordinated aileron command than with a symmetrical vertical tail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The MiG-23 is not alone: Many supersonic combat aircraft use ventral fins. See the picture below for an example where the effects of additional vertical tail area are compared to the effects of a ventral fin of the same area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/cinDn.jpg&quot; alt=&quot;comparison of fin and vertical tail area effectiveness&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Source: Ray Whitford: Fundamentals of fighter design)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At supersonic speeds, the stiff, low aspect ratio ventral fin has a nearly constant contribution to directional stability, whereas the wing-like vertical tail loses effectivity in proportion to the Prandtl-Glauert factor $\frac{1}{\sqrt{Ma^2-1}}$ because it bends and twists more due to its higher aspect ratio. The small ventral fin of the F-104 raised directional stability by 30% at Mach 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/NHshF.png&quot; alt=&quot;F-104 ventral fin contribution to directional stability&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Source: Ray Whitford: Fundamentals of fighter design)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high angles of attack, the vertical tail is in the wake of the fuselage which reduces local dynamic pressure and, consequently, effectivity. The ventral fin then is in ideal flow conditions, so it can help to stabilize the aircraft at high angle of attack, just when the fuselage contribution to instability is largest.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-28T06:41:23.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26475" PostTypeId="2" ParentId="26473" CreationDate="2016-03-28T07:40:47.667" Score="36" Body="&lt;p&gt;You can sail a seaplane, but there are a lot of considerations. For starters, it makes a big difference as to whether you're talking about a seaplane where the hull is in the water or a floatplane. A floatplane sitting up on its pontoons (floats) is more up in the wind, but it's also more susceptible to rough water because of its higher center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My personal experience with sailing a floatplane was with a J-3 cub with an 85 horse engine on rivers and lakes. If we wanted to back onto the shore, we had to sail it since there was no reverse pitch propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For purposes of explanation on how to do it, let's say that there's no wind, but we're on a river with enough current that the movement of the floatplane with the current when the engine is off gives the floatplane a wind relative to the water. Further let's say the river is flowing from east to west, and we want to back onto a beach on the north shore. We land and stop the engine upstream from the beach. As the floatplane drifts it will weathervane into the wind. Thus, with the controls neutralized, we'll be facing west and moving downstream in mid-river with the current, but not as fast the current because of the drag of the wind on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rule of thumb is that you point the tail towards the shore you wish to get to. We do that by applying left rudder and right aileron. Thus we have increased the drag on the left wing, which will swing the nose left, and the left rudder will also swing the nose left. Thus the nose is now pointed a few degrees toward the left shore (south), the tail toward the right shore (north). The airplane will then sail to the right shore (north) relative to the direction the aircraft nose is pointing because the the aircraft is moving backwards relative to the water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trick in this instance is vary the control input to arrive at the downstream point you want. For practice, I used to have students sail to alternate sides of the river on Oregon's Willamette River downstream from the city of Eugene.&lt;/p&gt;&#xA;" OwnerUserId="394" LastEditorUserId="394" LastEditDate="2016-03-28T20:00:26.107" LastActivityDate="2016-03-28T20:00:26.107" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26476" PostTypeId="1" AcceptedAnswerId="26480" CreationDate="2016-03-28T12:42:43.357" Score="5" ViewCount="3912" Body="&lt;p&gt;I was diagnosed with &lt;a href=&quot;https://en.wikipedia.org/wiki/Obstructive_sleep_apnea&quot; rel=&quot;nofollow&quot;&gt;Obstructive Sleep Apnea&lt;/a&gt; a few weeks ago.  I'm told that this somehow complicates my ability to get a license (I haven't started on my license yet.)  I'm having a hard time figuring out what the &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/dec_cons/disease_prot/osa/&quot; rel=&quot;nofollow&quot;&gt;FAA page is trying to tell me&lt;/a&gt; (and what the accompanying &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/media/FAA%20OSA%20Flow%20Chart.pdf&quot; rel=&quot;nofollow&quot;&gt;&quot;helpful chart&quot;&lt;/a&gt; means.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Could someone who speaks FAA style legalese give me a run down of what is being said?  I just want to know if I'm allowed to fly with treated sleep apnea, and what I need to do to make sure my medical is completed properly...&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-03-28T12:53:08.840" LastActivityDate="2016-03-29T00:24:56.137" Title="How do I get permission to fly when diagnosed with Sleep Apnea?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;&lt;ppl&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26477" PostTypeId="1" AcceptedAnswerId="26478" CreationDate="2016-03-28T13:30:28.730" Score="3" ViewCount="1758" Body="&lt;p&gt;This probably has already an answer somewhere, but probably don't know the proper search keys to find the information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Out of curiosity today I was trying to track a flight: one of my friend texted me about her flight being a lot late, and for fun I wanted to try to see if it was possible to understand what caused the delay. I knew flightradar24 by fame and found too flightaware by chance; I tried with the flight number (EZY2604...if this is the flight number) and couldn't find many information, 'till I realized that EZY2604 is probably something like the callsign for the route plus the scheduling, so with that I can only find details for this combination. And I can only track a plane which is flying, it seems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR:&lt;/strong&gt; how can I go from a flight number to the full route of the physical plane in the previous hours?&lt;/p&gt;&#xA;" OwnerUserId="9830" LastEditorUserId="9830" LastEditDate="2016-03-30T07:26:59.750" LastActivityDate="2016-03-30T11:26:23.650" Title="How to completely track a plane, not a flight?" Tags="&lt;online-tracking&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26478" PostTypeId="2" ParentId="26477" CreationDate="2016-03-28T13:33:29.353" Score="5" Body="&lt;p&gt;If you want to look for the airplane that flew a certain flight (U22604/EZY42EA for your case), you could go onto &lt;a href=&quot;http://flightradar24.com/data&quot; rel=&quot;nofollow&quot;&gt;flightradar24.com/data&lt;/a&gt; and search for that specific flight to find the list of aircraft which flew with the callsign and if you select any one of the planes, you can find out the flight history of that plane for the past few months. You could also search &lt;a href=&quot;https://flightaware.com/&quot; rel=&quot;nofollow&quot;&gt;flightaware.com/&lt;/a&gt; for flight history too.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-03-30T11:26:23.650" LastActivityDate="2016-03-30T11:26:23.650" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26479" PostTypeId="1" CreationDate="2016-03-28T13:45:50.983" Score="2" ViewCount="134" Body="&lt;p&gt;As per the forward to ICAO Annex 11, the status of a &quot;NOTE&quot; in any annex is - &lt;strong&gt;&quot;Notes included in the text, where appropriate, to give factual information or references bearing on the Standards or Recommended Practices in question, but not constituting part of the Standards or Recommended Practices.&quot;&lt;/strong&gt;&#xA;So, does it mean, a note given in the Annex does not hold any authority as it is not a part of the SARPs ?&lt;/p&gt;&#xA;" OwnerUserId="14227" LastEditorUserId="19" LastEditDate="2016-09-29T11:22:13.140" LastActivityDate="2016-09-29T11:22:13.140" Title="What is the status of &quot;Notes&quot; in ICAO Annexes?" Tags="&lt;icao-sarps&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26480" PostTypeId="2" ParentId="26476" CreationDate="2016-03-28T14:02:08.967" Score="7" Body="&lt;p&gt;When an Aviation Medical Examiner, AME, issues you a medical certificate, that is the relevant &quot;permission&quot; you need. Having sleep apnea complicates that issuance process, but doesn't necessarily make it impossible. Along with what you read on the AOPA forums, I would suggest making an appointment to talk with a local AME, preferably one who has accomplished this process with other pilots before. He can give you a picture of what the process is likely to look like in &lt;em&gt;your&lt;/em&gt; case, which is a better answer than assuming that your journey will look like that of somebody you read about on the internet. &lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="511" LastEditDate="2016-03-28T19:07:48.883" LastActivityDate="2016-03-28T19:07:48.883" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26481" PostTypeId="2" ParentId="26479" CreationDate="2016-03-28T14:20:27.343" Score="1" Body="&lt;p&gt;Yes. But there should not be a contradiction to the standard. Additional material usually serves to guide the user of the standard.&lt;/p&gt;&#xA;" OwnerDisplayName="user7241" LastActivityDate="2016-03-28T14:20:27.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26482" PostTypeId="2" ParentId="26477" CreationDate="2016-03-28T19:06:32.230" Score="4" Body="&lt;p&gt;EZY is the ICAO airline identifier for EasyJet. U2 is their IATA identifier. That's why it's listed as both. Normally Flight Aware and FlightRadar24 both use the 3-letter ICAO ID. It's a little unusual to have to search with the IATA code, but go figure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem with tracking a &lt;em&gt;plane&lt;/em&gt; instead of a &lt;em&gt;flight&lt;/em&gt; is that the system doesn't know which aircraft is being used until it actually pushes back. There's always the possibility of a last-minute aircraft change.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SMSvonderTann's method of looking up past flights and seeing what aircraft flew the route before will get you a &lt;em&gt;possible&lt;/em&gt;, or maybe even &lt;em&gt;probable&lt;/em&gt; tail no. but if the flight is delayed there's a possibility that it is being swapped out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see from the listing that the plane that flew EZY2604 from ATH to MXP flew the reverse EZY2603 from MXP to ATH right before. You can then try looking up 2603 and see what the status is on that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Problem is you never really know for sure if they might change the aircraft until it's in the air. And a delay makes that more likely.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-28T19:06:32.230" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26483" PostTypeId="1" AcceptedAnswerId="26485" CreationDate="2016-03-28T19:46:03.740" Score="26" ViewCount="4398" Body="&lt;p&gt;As I understand it (I'm not a pilot), radio communications are a more-or-less first come first served proposition. If I'm in busy airspace with near constant communication between ATC &amp;amp; aircraft, how do I break in to make contact with the ATC for whatever purpose necessary (establishing comms to enter airspace, or whatever the situation may be)?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="487" LastEditDate="2016-03-29T20:05:37.383" LastActivityDate="2016-03-31T13:15:36.990" Title="How do I get attention on a busy radio channel?" Tags="&lt;radio-communications&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26484" PostTypeId="2" ParentId="26483" CreationDate="2016-03-28T20:05:02.167" Score="16" Body="&lt;p&gt;Key up the mic and state:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Who you're contacting (e.g. Seattle Approach)&lt;/li&gt;&#xA;&lt;li&gt;Who you are (e.g. Skyhawk 1234)&lt;/li&gt;&#xA;&lt;li&gt;Where you are (e.g. 5 west of Bremerton)&lt;/li&gt;&#xA;&lt;li&gt;Your altitude (e.g. 5500)&lt;/li&gt;&#xA;&lt;li&gt;Your request (e.g. VFR flight following to Renton)&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If the frequency is really busy, some people will substitute #3, 4, 5 with &quot;request&quot; (e.g. &quot;Seattle Approach, Skyhawk 1234, VFR request&quot;). Once the controller responds the remaining details can be filled in.&lt;/p&gt;&#xA;" OwnerUserId="1520" LastEditorUserId="5517" LastEditDate="2016-03-31T13:15:36.990" LastActivityDate="2016-03-31T13:15:36.990" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26485" PostTypeId="2" ParentId="26483" CreationDate="2016-03-28T20:05:02.870" Score="29" Body="&lt;p&gt;As Ron commented, the basic answer is that you try to anticipate when a short gap is going to be, and jump on before someone else does. It sounds a bit daunting, but it actually works out pretty well in practice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That being said, it's not &lt;em&gt;exactly&lt;/em&gt; first come first serve. ATC tends to prioritize talking to the aircraft which need the most immediate instructions. So, an aircraft on final is going to get more priority than one which hasn't even entered the airspace yet. Even if you manage to get your request in, if the controller has a more immediate issue to address, you may get completely ignored. Sometimes they'll come back with &quot;calling approach, say again&quot; or sometimes you just have to try again later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Either way, it's usually not too difficult to stay out of trouble long enough to get someone's attention. If you're IFR or have already made initial contact, you can probably just continue on your path and you'll eventually become a big enough priority for them that they'll call &lt;em&gt;you&lt;/em&gt; if you still haven't a chance to get a word in. If you're VFR and haven't made initial contact, you can probably just avoid the airspace for a few minutes.&lt;/p&gt;&#xA;" OwnerUserId="6" LastActivityDate="2016-03-28T20:05:02.870" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26487" PostTypeId="2" ParentId="26473" CreationDate="2016-03-28T20:46:59.127" Score="7" Body="&lt;p&gt;I know this is not what was asked, but I couldn't resist. There was indeed a seaplane that could be sailed: A sailplane with a seaplane hull. It was a curiosity and built only because none had been built before - or ever since.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zesbq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zesbq.jpg&quot; alt=&quot;DFS Seeadler floating on water&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/DFS_Seeadler&quot; rel=&quot;nofollow noreferrer&quot;&gt;DFS Seeadler&lt;/a&gt; floating on water (picture &lt;a href=&quot;http://www.luftarchiv.de/segel/seeadler1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). First flight was in 1935, and the official reasoning was to create a modern sailplane for clubs without access to a good airfield, but a lake nearby. But I guess the designer Hans Jacobs knew already how flimsy the official reasoning was: Below the keeled fuselage bottom was a wooden skid to allow landing on land. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-28T20:46:59.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26488" PostTypeId="2" ParentId="26483" CreationDate="2016-03-28T22:21:34.087" Score="7" Body="&lt;p&gt;The first thing to get clear is: who are we talking to here? a tower? an ARTCC? what?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my experience the biggest problem can be trying to reach a busy tower for a small or medium-sized airport. In other situations, usually ATC calls you, not the other way around. For example, if you request vectoring, you only have to do it once; after that they call you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are trying to reach a tower and they are tied up, it can be a real problem because as you get closer to the airport you need an answer. In one or two cases I have actually had to circle to wait for some chat head to shut up so I could talk to the tower and get instructions for an approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Commercial flights have this problem less because they are operating on filed flight plans, so the tower is ready and waiting for them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another serious problem is when you are in the pattern on downwind and the tower is too busy to give you a landing clearance. In this situation all you can do is to keep flying downwind. Sometimes it gets ridiculous. I have flown literally miles downwind waiting for clearance to turn onto final, which then turns into this loooooong 5 mile final.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you fly downwind too far, you might even have to leave the pattern completely and start the whole process all over again, although this has never happened to me.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-03-28T22:21:34.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26489" PostTypeId="1" AcceptedAnswerId="26495" CreationDate="2016-03-28T23:26:38.907" Score="11" ViewCount="1722" Body="&lt;p&gt;I marked them with black circles. What are they for? &#xA;&lt;a href=&quot;https://i.stack.imgur.com/LVh0S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LVh0S.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://2.bp.blogspot.com/-oHdmyDdrYAs/UUR0gIJO8-I/AAAAAAAAStg/1tMMdmyJCG8/s1600/Slide.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt; (modified)&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="1696" LastEditDate="2016-06-14T16:58:52.950" LastActivityDate="2017-02-08T19:04:13.703" Title="What are these little things on the evacuation slide?" Tags="&lt;evacuation&gt;&lt;emergency-procedures&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26490" PostTypeId="1" AcceptedAnswerId="26527" CreationDate="2016-03-28T23:46:41.193" Score="1" ViewCount="427" Body="&lt;p&gt;I was wondering if there is anyone that offers on-line searching of prior flight plans.&lt;/p&gt;&#xA;" OwnerUserId="13972" LastActivityDate="2016-03-30T02:38:06.103" Title="Is there a service to review prior flight plans?" Tags="&lt;flight-planning&gt;&lt;flight-plans&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26491" PostTypeId="1" CreationDate="2016-03-28T23:49:53.053" Score="2" ViewCount="619" Body="&lt;p&gt;Some of my flights are tracked on sites like Flightradar24 and others are not, regardless of flight plans being opened and closed. It would be nice to go to a website that tracks all flights, so I can review the flight dynamics after I land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am interested in a website that provides this service, not an app (I have had limited success with these).&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="62" LastEditDate="2016-11-10T13:54:38.527" LastActivityDate="2016-11-10T13:54:38.527" Title="Is there a site that tracks all flights?" Tags="&lt;flight-tracking&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26492" PostTypeId="2" ParentId="26476" CreationDate="2016-03-29T00:24:56.137" Score="4" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/a/26480/3677&quot;&gt;Ralph J Covered&lt;/a&gt; it pretty well but I will expand on what he said with a few other facts. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality you only need one AME to sign you off. With that in mind if the first one says you are a no go that does not mean that its said an done. Another AME may have a different opinion and sign off on your medical. An AME may be able to give you a good feel if not a straight answer over the phone if you can accurately describe your condition. I see you have this tagged as PPL so I will assume you are going for you PPL and asking in that regard. If you are talking about an aviation career I am under the impression that some of the majors do not let you chose your own AME and may make you go to their in-house doctor. This may be an issue down the line if your local AME cleared you but the airline you eventually work for has a different opinion.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While still under debate, &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2015/December/09/Third-class-medical-FAQs&quot; rel=&quot;nofollow noreferrer&quot;&gt;third class medical reform&lt;/a&gt; may change the playing field for all of this and you may no longer need a medical cert to fly private.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;AOPA is a great resource for this kind of thing and they are one of the big parties advocating for third class reform.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-03-29T00:24:56.137" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26494" PostTypeId="2" ParentId="26413" CreationDate="2016-03-29T01:42:20.970" Score="0" Body="&lt;p&gt;It's most likely an Expect Further Clearance (EFC) timer. You didn't mention the aircraft type but there are several references to it online: &lt;a href=&quot;http://garmin.blogs.com/aviationalerts/2015/03/service-advisory-1507-rev-b-published-hold-can-be-shown-on-the-wrong-side.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Garmin service advisory&lt;/a&gt;; Seneca V &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2013/February/20/Exclusive-first-look-Seneca-goes-G1000&quot; rel=&quot;nofollow noreferrer&quot;&gt;impressions&lt;/a&gt;; Archer manual &lt;a href=&quot;http://forums.jetcareers.com/threads/unpublished-hold-programming-in-g1000-gns530w.115575/page-3#post-2312192&quot; rel=&quot;nofollow noreferrer&quot;&gt;quoted in a forum&lt;/a&gt;. My G1000 experience is in a C172 and I've never seen it there (I can't find it in the manual either) but the features are different depending on the aircraft, so it's possible that EFC timing just isn't in the C172 version.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2020-12-21T22:54:07.180" LastActivityDate="2020-12-21T22:54:07.180" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26495" PostTypeId="2" ParentId="26489" CreationDate="2016-03-29T02:01:28.963" Score="11" Body="&lt;p&gt;@ratchet freak is correct. The protrusions are canopy poles, where the canopy in the evacuation slide/raft is propped up. The image below shows a canopy propped on them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J40Ni.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J40Ni.jpg&quot; alt=&quot;Canopy&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.tulmar.com/images/site_client/documents/download_center/Manuals/Training_Slides/Single_and_Dual_Lane_Generic_Training_Slide.pdf&quot;&gt;tulmar.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the document:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The canopy is supported in the center in 4 places by inflatable yellow “CANOPY END SUPPORTS” and “CANOPY CENTER SUPPORTS”, and supported along the sides by 14 numbered supports on the top of the slides inflatable structure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here's a closeup of the support from the same document.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5gEak.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5gEak.jpg&quot; alt=&quot;Canopy support&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="7532" LastEditDate="2016-03-29T02:51:45.183" LastActivityDate="2016-03-29T02:51:45.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26496" PostTypeId="1" AcceptedAnswerId="26503" CreationDate="2016-03-29T04:31:42.463" Score="7" ViewCount="530" Body="&lt;p&gt;Took off from LHR in a B747-400 on Sunday and I experienced something new that is puzzling me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After take off as the aircraft was climbing it seemed to continually speed up and slow down at the rate of once every one or two seconds. Kind of like an oscillation in the direction of travel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After a few minutes of this it stopped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What caused this to happen?&lt;/p&gt;&#xA;" OwnerUserId="14233" LastEditorUserId="1696" LastEditDate="2016-03-29T15:48:26.467" LastActivityDate="2016-03-30T13:15:32.717" Title="What could be the reason for a feeling of speed oscillation after takeoff in a 747?" Tags="&lt;airliner&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26497" PostTypeId="2" ParentId="26473" CreationDate="2016-03-29T05:21:26.133" Score="11" Body="&lt;p&gt;It's been done at least once before.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 1925 a US Navy PN-9 landed in the Pacific when it ran out of fuel on the way to Hawai'i. The crew then rigged a sail from parts of the canvas wings and sailed their plane over 400 miles (in nine days) to reach the islands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://timeandnavigation.si.edu/multimedia-asset/naval-aircraft-factory-pn-9-116-scale&quot;&gt;http://timeandnavigation.si.edu/multimedia-asset/naval-aircraft-factory-pn-9-116-scale&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14234" LastEditorUserId="1467" LastEditDate="2016-03-29T06:35:30.317" LastActivityDate="2016-03-29T06:35:30.317" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26498" PostTypeId="1" AcceptedAnswerId="26499" CreationDate="2016-03-29T07:29:56.253" Score="8" ViewCount="1311" Body="&lt;p&gt;One of the planes I worked on had ground spoiler response checked with proximity sensors. The reason mentioned for that was - &quot;The ground spoiler is hydraulic only - hence its response will be checked with proximity sensors&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing gear control unit reads the proximity sensors and flight control system receives the signals indicating deployment of ground spoilers by landing gear control unit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are proximity sensors?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are they used because the surface is hydraulic?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="1696" LastEditDate="2016-06-14T16:32:25.030" LastActivityDate="2016-06-14T16:32:25.030" Title="What is the purpose of proximity sensors on hydraulic systems?" Tags="&lt;spoilers&gt;&lt;sensors&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26499" PostTypeId="2" ParentId="26498" CreationDate="2016-03-29T08:13:35.123" Score="6" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Proximity_sensor&quot; rel=&quot;nofollow&quot;&gt;proximity sensor&lt;/a&gt; is any sensor that detects whether there is something in its proximity (within specified distance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are many kinds of proximity sensors (optical, magnetic, capacitive etc.) that detect different kinds of target objects and to various distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, proximity sensor is used to detect position of the spoiler. Proximity sensors are preferred over micro-switches because they are more reliable, since they have no moving parts and thus don't wear out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For parts actuated with hydraulics they are the only way to detect the position, since hydraulic actuators don't provide any direct way for detecting their position (compared to electric actuators, where in some cases the response of the actuator can be used to detect the position; the principle is similar to a magnetic proximity sensor anyway though).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-30T12:07:02.233" LastActivityDate="2016-03-30T12:07:02.233" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26500" PostTypeId="1" AcceptedAnswerId="26501" CreationDate="2016-03-29T08:53:12.343" Score="7" ViewCount="419" Body="&lt;p&gt;The Bombardier C-Series aircraft has a movable horizontal stabilizer. It also has Trim Up/Down (discrete) switches in the cockpit. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Is the aircraft also equipped with trim tabs?&lt;/li&gt;&#xA;&lt;li&gt;If so, when pilot adjusts the trim using the trim switches, which surface moves - horizontal stabilizer or trim tabs?&lt;/li&gt;&#xA;&lt;li&gt;If an aircraft has both trim tabs and movable stabilizer, when are the trim tabs used for trimming?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="1467" LastEditDate="2016-03-29T08:57:34.803" LastActivityDate="2016-03-31T06:45:20.117" Title="Are elevator trim tabs required for an aircraft equipped with movable horizontal stabilizer?" Tags="&lt;trim&gt;&lt;trim-tab&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26501" PostTypeId="2" ParentId="26500" CreationDate="2016-03-29T09:13:45.260" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Is the aircraft also equipped with trim tabs?&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From the images available online (this is a youtube screenshot, click it to see the larger version), no. And see point 3 on why I was not expecting any different.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/h9R3Y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/h9R3Y.jpg&quot; alt=&quot;Bombardier CS300&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;3&quot;&gt;&#xA;  &lt;li&gt;If an aircraft has both trim tabs and movable stabilizer&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I do not see the need of such a solution, a trimmable stabilizer is already optimal, adding trim tabs would increase the complexity of the system with no significant benefits, as the use of tabs increases drag, something that a THS does not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not know of any aircraft that uses both THS and tabs, but, should one exist, I presume one would use the tabs only if significantly faster than the THS actuation system, allowing the aircraft to be trimmed more rapidly, but afterwards the THS would take care of the trim allowing the tabs to go back to neutral and reducing drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This solution would be hardly beneficial, since commercial aircraft (as the one that prompted your question) do not preform manoeuvers that require such fast (and eventually frequent) re-trimming.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition, as GHB has pointed out in the comments, the elevator is already able to take care of fast transients, the trim tab would only provide unneeded complications (in the design, the maintenance, the control).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-03-31T06:45:20.117" LastActivityDate="2016-03-31T06:45:20.117" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26503" PostTypeId="2" ParentId="26496" CreationDate="2016-03-29T10:35:27.857" Score="13" Body="&lt;p&gt;There are a whole bunch of possible reasons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing to note is that, from inside the cabin it can be very difficult to tell the difference between speeding up/slowing down, pitching up/down, and the rise and fall from turbulence (particularly when in a climb). And one I wasn't aware of but as pointed out by Sami, the air conditioning pressure varying because of a malfunction in the engine bleed or pack valve.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why could it be happening?&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Turbulence causing the aircraft to gentle rise/fall, which, in a climb, is fairly akin to small acceleration/decelerations - both to our inner ear, and in terms of what's physically happening to the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The air conditioning pressure rising and falling more than usual rather than maintaining a constant pressure&lt;/li&gt;&#xA;&lt;li&gt;Slight pitch up/down manoeuvres, possibly from a relatively inexperienced pilot flying the aircraft&lt;/li&gt;&#xA;&lt;li&gt;The auto-throttle throwing a hissy fit or, if climbing at 250 knots under 10,000 ft, oscillating slightly in order to stay at/below the 250 knot speed limit&lt;/li&gt;&#xA;&lt;li&gt;The pilots adjusting thrust manually, possibly for the same reason as above&lt;/li&gt;&#xA;&lt;li&gt;A gusting head/tailwind. Particularly noticeable near the ground and when in a climb, and can cause a feeling of acceleration/deceleration.&lt;/li&gt;&#xA;&lt;li&gt;A malfunction in one of the engines causing the power to vary slightly. It's possible this was only noticeable at takeoff/climb thrust levels, and disappeared when throttling back&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Typically you'd expect it to be due to either turbulence or a gusting wind, but there are several systems which could develop a small, fairly benign fault and have this symptom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: As noted by user Jamiec, Storm Katie (a reasonably strong storm) was over the UK at the time, which would certainly back up turbulence/gusting winds being the most likely culprit&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3504" LastEditDate="2016-03-30T13:15:32.717" LastActivityDate="2016-03-30T13:15:32.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26504" PostTypeId="2" ParentId="26471" CreationDate="2016-03-29T13:01:47.183" Score="5" Body="&lt;p&gt;In this scenario, you do in fact have two legal options -- although you must decide if they are safe.&lt;/p&gt;&#xA;&lt;p&gt;First, you can cancel IFR when you break out on the approach and switch to SVFR (this was mentioned in a comment by @pondlife). You can even coordinate it in advance with the approach controller, and even specify that you intend to do this in the &amp;quot;NOTES&amp;quot; section of the IFR flight plan. Although its legal for airplanes, it is more typically a helicopter procedure, due to heli's lower IFR and SVFR minimums. The process would be to descend on the straight-in approach, and when you can satisfy SVFR requirements, cancel IFR and substitute SVFR. You can then complete the approach to your desired circling runway.&lt;/p&gt;&#xA;&lt;p&gt;The second option you might have is a contact approach (see below), although I have never heard of anyone actually requesting one in real weather. With the contact approach, you would ask for vectors to the airport, preferably towards Runway 26, at the MVA. If you can see the ground during the vector, and believe you can satisfy the contact parameters, you then request a contact approach, and follow the procedures outlined below.&lt;/p&gt;&#xA;&lt;p&gt;Both of these scenarios are fairly obscure precisely because they do not afford you the safety margins that a straight-in or even a circling approach does.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;Contact Approaches&lt;/h3&gt;&#xA;&lt;p&gt;If conditions permit, pilots can request a contact approach,  which&#xA;is  then  authorized  by  the  controller.  A  contact   approach&#xA;cannot be initiated by ATC. This procedure may  be  used  instead  of&#xA;the  published  procedure  to  expedite   arrival, as long as the&#xA;airport has a SIAP the reported ground  visibility is at least 1 SM,&#xA;and pilots are able to remain clear  of  clouds  with  at  least  one&#xA;statute  mile  flight  visibility   throughout the approach. Some&#xA;advantages of a contact  approach  are  that  it  usually  requires&#xA;less  time  than  the   published instrument procedure, it allows&#xA;pilots to retain  the  IFR  clearance,  and  provides  separation&#xA;from  IFR  and   SVFR traffic. On the other hand, obstruction&#xA;clearances and  VFR  traffic  avoidance  becomes  the  pilot’s&#xA;responsibility.   Unless otherwise restricted, the pilot may find it&#xA;necessary  to descend, climb, or fly a circuitous route to the airport&#xA;to  maintain cloud clearance or terrain/ obstruction clearance.&lt;/p&gt;&#xA;&lt;p&gt;The main  differences  between  a  visual  approach  and   a  contact&#xA;approach  are:  a  pilot  must  request  a  contact   approach,  while&#xA;a  visual  approach  may  be  assigned  by   ATC or requested by the&#xA;pilot; and a contact approach may  be approved with 1 mile visibility&#xA;if the flight can remain  clear of clouds, while a visual approach&#xA;requires the pilot  to  have  the  airport  in  sight,  or  a&#xA;preceding  aircraft  to  be   followed, and the ceiling must be at&#xA;least 1,000 feet AGL  with at least 3 SM visibility.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Source: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/chapter_4.pdf#page=58&quot; rel=&quot;nofollow noreferrer&quot;&gt;Instrument Procedures Handbook, Chapter 4 (Approaches). “Contact Approaches,” p. 4-58&lt;/a&gt; (49 MB PDF)&lt;/strong&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-08-21T12:57:50.033" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26506" PostTypeId="1" CreationDate="2016-03-29T13:56:29.890" Score="2" ViewCount="876" Body="&lt;h2&gt;STALL:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I believe a simple software update to the existing on-board flight computers could - possibly - save lives.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots need to be indicated possible errors by the on-board computers more detailed and more clearly.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Backround: after having watched these 3 reports on:&lt;/h2&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;       1) crash Air France flight 447 to Rio into the Atlantik in 2009,&#xA;          an A330-203 (reason:stall, technical problem: air speed sensor(s)  &#xA;          frozen)&#xA;&#xA;   2) crash of Air New Zealand owned XL-Airways A320-200 in 2008    &#xA;          (reason: stall, technical problem: pitch sensor frozen)&#xA;&#xA;       3) crash Birgenair 301 in 1996 of 757-200 from the Dominican Republic&#xA;          (reason: stall, technical problem: air speed sensor)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;In general, these very often occuring problems with a faulty or temporarily faulty sensors (i.e. frozen) such as an &#xA;air speed sensor should be directly indicated to the pilots by better software in the current on-baord computers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A more relevant message to the pilots could and should be indicated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example: &quot;POSSIBLE ERROR - Air speed sensor. Check pitch.  If pitch within the range of xx - xx then possibly no stall situation present&quot;.&#xA;[the pitch value to be used could come from an internal look-up table in the on-board computers memory for the given aircraft under its current load conditions].&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of Air France, had the pilots taken no action other than maintaining altidude and air speed, nothing would have happened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As they took incorrect action, assuming there was a stall situation, the whole problem emerged in the first place.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The on-board computers should &quot;know&quot;:&#xA;IF the air speed does not match +/- the air speed the plane should be doing for its given amount of thrust by the engines&#xA;[lookup-table in software],&#xA;then: (assuming engines and plane is ok), there must either be a problem with the pitch sensor(s) or air speed sensor(s).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As these sensors are doubled, they are checked against each other.&#xA;If , for example, two air speed sensors differ from each other, as I believe it is currently done, then it is &#xA;assumed by the on-boad computers that one of these is faulty, but the on board computer does not conclude which one it may be and thus does not &quot;know&quot; what air speed it should use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;BUT, as explained above, WHY NOT: when checking against prevailing thrust and pitch and other relevant sensors, the on-board&#xA;computers can come to an estimation for the given aircraft's actual air speed currently present [lookup-table in on-baord computers memory].&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And then, this information with the big mention of POSSIBILITY should be indicated in the warning messages,&#xA;to give pilots a head start in analyzing and identifying the problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Currently, it seems to me, that unneccessarily, much valuable time is spent by the piolots having to first analyze the&#xA;situation from scratch and then decide on which action is needed  to regain control from the stall, by which time it is often too &#xA;late as  altidude/air speed are by then too low for a recovery.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was the case for (1) Air France as well as for (2) XL-Airlines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, (1, Air France) had the problem that if one pilot pulled the stick backwards and the other pilot moved the stick forward,&#xA;the action was cancelled out and no indication was given as far as I know, so pilots lost further valuable time arguing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In (2, XL-Airlines) also had the problem that the A320-200 would in the stall emergency situation only respond to the &#xA;trim wheel and not to the stick.&#xA;The pilots realised this too late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The on-board computer indicated this on its screen, but it was overlooked, as obviously very unusual.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is as if when driving a car, suddenly it is no longer the steering whel we need to change direction but the handbrake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What were the developers thinking here, I really do not understand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Last but not least: the constant alarm noise should after a while be tuned down somewhat and the sound level reduced - it does nothing to get the &#xA;situation resolved faster but instead causes stress levels to soar even higher, which is detrimental to pilots acting &#xA;calmly and in getting the situation under control..&lt;/p&gt;&#xA;" OwnerUserId="14236" LastActivityDate="2016-03-29T14:42:37.713" Title="stall on commercial airliner - why is there no better on-board software?" Tags="&lt;airliner&gt;&lt;stall&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ClosedDate="2016-03-29T15:23:04.323" ContentLicense="CC BY-SA 3.0" />
  <row Id="26507" PostTypeId="2" ParentId="26506" CreationDate="2016-03-29T14:33:00.370" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;For example: &quot;POSSIBLE ERROR - Air speed sensor. Check pitch. If pitch within the range of xx - xx then possibly no stall situation present&quot;. [the pitch value to be used could come from an internal look-up table in the on-board computers memory for the given aircraft under its current load conditions].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An aircraft can stall at any pitch angle and many different speeds, so pitch is not a good indicator of the onset of a stall. A better indicator is Angle of Attack, but in many cases those sensors freeze over. You cannot measure AoA without a physical sensor using MEMS or INS components. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The on-board computers should &quot;know&quot;: IF the air speed does not match +/- the air speed the plane should be doing for its given amount of thrust by the engines [lookup-table in software], then: (assuming engines and plane is ok), there must either be a problem with the pitch sensor(s) or air speed sensor(s).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A problem with the pitch sensor/airspeed sensor does not automatically mean a stall, and also should not present additional stall warnings without the actual stall condition. How would you separate the two? Just like you don't want them to overlook a warning, you also don't want to present too many that aren't relevant as it will increase the time it takes to figure out what is going on.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;BUT, as explained above, WHY NOT: when checking against prevailing thrust and pitch and other relevant sensors, the on-board computers can come to an estimation for the given aircraft's actual air speed currently present [lookup-table in on-baord computers memory].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Imagine flying from clean air into the jet stream as the sensors fail. You haven't changed the thrust levels and suddenly you are presented with a tail wind which greatly reduces your airspeed. Engine thrust does not immediately react to the surrounding air mass, you can't say that for every condition Thrust X = Airspeed Y, its not a simple correlation especially given changing conditions. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And then, this information with the big mention of POSSIBILITY should be indicated in the warning messages, to give pilots a head start in analyzing and identifying the problem.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, this is absolutely not a good thing to do. Like I said above, you don't want to present warning conditions about the &lt;strong&gt;possibility&lt;/strong&gt; of a situation. The pilot should be able to infer from &lt;em&gt;airspeed invalid&lt;/em&gt; warnings that the possibility of a stall is there, and fly the aircraft appropriately. Presenting too many warnings is worse than not enough.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Currently, it seems to me, that unneccessarily, much valuable time is spent by the piolots having to first analyze the situation from scratch and then decide on which action is needed to regain control from the stall, by which time it is often too late as altidude/air speed are by then too low for a recovery&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Pilots are trained for stall recognition and recovery and the recovery procedure after recognition should be a reaction without a lot of thought. The problem with the Air France flight is that the pilots did not recognize the stall even after the airspeed sensors started working again. By the time the captain realized that one person was climbing while the other person was descending, it was too late:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;02:13:40 (Robert) Remonte... remonte... remonte... remonte...&lt;br/&gt;&#xA;  &lt;em&gt;Climb... climb... climb... climb...&lt;/em&gt;&lt;br/&gt;&#xA;  02:13:42 (Captain) Non, non, non... Ne remonte pas... non, non.&lt;br/&gt;&#xA;  &lt;em&gt;No, no, no... Don't climb... no, no.&lt;/em&gt; &lt;br/&gt;&#xA;  02:13:43 (Robert) Alors descends... Alors, donne-moi les commandes... À moi les commandes!&lt;br/&gt;&#xA;  &lt;em&gt;Descend, then... Give me the controls... Give me the controls!&lt;/em&gt;&lt;br/&gt;&#xA;  02:14:23 (Robert) Putain, on va taper... C'est pas vrai!&lt;br/&gt;&#xA;  &lt;em&gt;Damn it, we're going to crash... This can't be happening!&lt;/em&gt;&lt;br/&gt;&#xA;  02:14:25 (Bonin) Mais qu'est-ce que se passe?&lt;br/&gt;&#xA;  &lt;em&gt;But what's happening?&lt;/em&gt;&lt;br/&gt;&#xA;  02:14:27 (Captain) 10 degrès d'assiette...&lt;br/&gt;&#xA;  &lt;em&gt;Ten degrees of pitch...&lt;/em&gt;&lt;br/&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Exactly 1.4 seconds later, the cockpit voice recorder stops. That means when the pilot realized that they had the wrong control inputs at 2:13:42 it was less than 60 seconds from impacting the water, no way they would have been able to recover. So the take-away from AF447 was that pilots needed to be trained to recognize a stall and the proper recovery techniques. The pilots had regained control at 2:10:38 and the airspeed sensors were reading normally at that time. By 2:10:55 all avionics were functional. They put the aircraft into another stall at 2:11:03 when they tried to climb at TOGA power around 37,500 feet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Again, the issue is overload. You don't want to overload the pilots with too much information. A stall horn and the red X over the airspeed indication should be enough for the pilot to realize to lower the nose and increase speed. AF447 was a wake-up call to commercial operators about the lack of hand-flying skills in todays pilots and quite a few good changes came from it including stall awareness training and recovery training on a reoccurring basis.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-03-29T14:42:37.713" LastActivityDate="2016-03-29T14:42:37.713" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26508" PostTypeId="2" ParentId="25089" CreationDate="2016-03-29T15:31:06.970" Score="3" Body="&lt;p&gt;For a given lift coefficient, boundary layer drag is smaller for the straight wing configuration, and lift-induced drag is larger for straight wing.  These conflicting effects may give an advantage to straight wing at low subsonic speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At speeds of about Mach 0.8 you begin to get wave drag because the flow over the wing is not uniform, and in some regions you have supersonic flow.  The wave drag is much less for swept wings, roughly in proportion to the aspect ratio.  So when you are trying to push the plane to Mach 1, swept wings make your job easier.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At Mach 1 and a bit higher more and more of the wing region experiences supersonic flow, and the shock drag is dominant.  Again, swept wings have a huge  drag advantage (not to mention a control advantage).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But pretty soon, certainly by Mach 2, both wings have the same amount of wave drag, and the shock drag becomes less important as the region near Mach 1 disappears.  And now we come to our first observation, about boundary layer and lift-induced drag roughly balancing.  Except --&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;At supersonic flow there is no lift-induced drag&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is because the &quot;wake cannot be felt upstream.&quot;  More accurately, the penalty associated with turning the flow to generate lift is captured over the wing surface and what happens downstream of the wing cannot affect the flow over the wing because &quot;knowledge&quot; of what happens downstream propagates at the speed of sound.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we have to remove, from our calculations for each type of wing, the lift-induced drag, which had been greater in the straight wing.  And this makes the straight wing drag coefficient lower at moderately high supersonic speeds, compared to the swept wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I may be wrong here because fluid dynamics is famous for introducing subtle effects that nobody would have anticipated, but I believe this issue is understood and the trade-off mentioned is the heuristic reason.&lt;/p&gt;&#xA;" OwnerUserId="12120" LastActivityDate="2016-03-29T15:31:06.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26509" PostTypeId="2" ParentId="26491" CreationDate="2016-03-29T16:03:33.227" Score="5" Body="&lt;p&gt;No, there will always be flights that are private, or for any other reason not traceable. &lt;/p&gt;&#xA;" OwnerUserId="14237" LastActivityDate="2016-03-29T16:03:33.227" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26511" PostTypeId="2" ParentId="26471" CreationDate="2016-03-29T16:29:18.797" Score="7" Body="&lt;h2&gt;Intro&lt;/h2&gt;&#xA;&lt;p&gt;This is a bit of an odd situation, but they have a good reason for doing what they did.&lt;/p&gt;&#xA;&lt;p&gt;First of all, each instrument approach is designed to be a stand-alone procedure, and the designers consider that you may not have any of the other approach plates when you are flying a particular procedure.  All of the information that you need to fly the approach is included on its individual chart.&lt;/p&gt;&#xA;&lt;h2&gt;Procedure differences&lt;/h2&gt;&#xA;&lt;p&gt;Now, let's look at the ILS and LOC approaches more closely with that in mind.  Very often, these two approaches will be combined into one procedure.  This has a benefit in that if the glideslope fails, you can simply descend to LOC minimums and continue the approach without having to go missed.  In this case though, they are two different procedures.  Why?&lt;/p&gt;&#xA;&lt;p&gt;Equipment requirements:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The ILS RWY 31 approach requires an ILS receiver, plus ADF or DME (per the note, and is needed to identify the holding point).&lt;/li&gt;&#xA;&lt;li&gt;The LOC/DME RWY 31 approach requires the LOC receiver &lt;strong&gt;and&lt;/strong&gt; DME.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The designers wanted someone without DME to be able to fly the ILS procedure.  Because of this, the missed approach point is only identified by reaching the decision height (282' MSL in this case) while on the glideslope.  If  you leveled off sooner, using only the equipment that is &lt;strong&gt;required&lt;/strong&gt; to fly the approach, you have no way to identify the missed approach point (or the visual descent point for that matter).  When you reached your self-imposed MDA, you would level off and continue to fly until the MAP if you don't break out.  Wherever that may be....  This is why there are no circling minimums.&lt;/p&gt;&#xA;&lt;p&gt;The LOC/DME procedure on the other hand requires DME, and specifies that the MAP is at 0.4 DME.  Now you can descend to the specified minimums and continue along with no visual references until you reach the defined MAP, at which point you would fly the published missed approach procedure.  If you are at the MDA and see the airport earlier, then you can circle in accordance with circling procedures if you have been cleared to do so.&lt;/p&gt;&#xA;&lt;p&gt;The other two procedures require GPS or a VOR receiver, and define the MAP according to the required equipment, so also have circling minimums.&lt;/p&gt;&#xA;&lt;h2&gt;Resolution&lt;/h2&gt;&#xA;&lt;p&gt;Now that we know why they did this, what can we do differently?  &lt;strong&gt;Plan ahead.&lt;/strong&gt;  You should know the weather before you are given an approach (via preflight planning and the ATIS). You should know which approaches are available and which one that you want to fly &lt;strong&gt;before&lt;/strong&gt; ATC assigns it.  If the ATIS states that they are using the ILS RWY 31 approach and you know that you want to land on a different runway, request the specific procedure and runway that you want on initial contact with approach.&lt;/p&gt;&#xA;&lt;p&gt;As others have said, don't switch procedures in the middle of an approach.  If you can't fly it, go missed and get properly setup / familiar with the procedure and fly the procedure when you are prepared for it.&lt;/p&gt;&#xA;&lt;p&gt;If you decide to continue with the current procedure, you either land straight in, go missed, or request a contact approach to your preferred runway if you break out in time (this option would most likely require prior coordination since there may be traffic following too closely for them to approve it).  Do &lt;strong&gt;not&lt;/strong&gt; cancel IFR, as this isn't legal without a 1,000 ft. ceiling, and pilots have been violated for that.&lt;/p&gt;&#xA;&lt;p&gt;The mountains surrounding the area that you are flying in will not be forgiving if you try to get into a contest of wills or rush and make a mistake.&lt;/p&gt;&#xA;&lt;p&gt;Lastly, make sure that whatever you decide to do has been coordinated with ATC and that they know what you want to do and give you a clearance to do so.  For everybody's well-being, you don't want to surprise anyone by doing something unexpected.&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-29T16:36:30.587" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26512" PostTypeId="1" AcceptedAnswerId="26513" CreationDate="2016-03-29T16:34:09.037" Score="39" ViewCount="4947" Body="&lt;p&gt;In the following frames, you can see a guy in green showing a panel-like device with numbers on it to the pilot of the Super-Hornet that is about to launch from the carrier USS John C. Stennis. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is this panel for? &lt;/li&gt;&#xA;&lt;li&gt;What information is the pilot given?&lt;/li&gt;&#xA;&lt;li&gt;Why just before takeoff and not while boarding/briefing?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/a0fms.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a0fms.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;https://youtu.be/nPZV6btBGx4?t=3m50s&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&#xA;I won't accept &lt;a href=&quot;https://aviation.stackexchange.com/questions/25084/what-is-the-force-exerted-by-the-catapult-on-aircraft-carriers&quot;&gt;this&lt;/a&gt; question as a duplicate. It may contain the answer &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Taxiing up to the catapult, a green shirt will hold up the weight board. If the weight on the board matches the weight on the weight chit, acknowledge ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;but the question isn't really about that part and quite &quot;hidden&quot;.&lt;/p&gt;&#xA;" OwnerUserId="9544" LastEditorUserId="14897" LastEditDate="2017-09-26T15:03:19.033" LastActivityDate="2017-09-26T15:03:19.033" Title="What is the guy in green showing to the F/A-18E pilot before catapult launch?" Tags="&lt;military&gt;&lt;takeoff&gt;&lt;fighter&gt;&lt;aircraft-carrier&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26513" PostTypeId="2" ParentId="26512" CreationDate="2016-03-29T16:51:56.187" Score="38" Body="&lt;p&gt;That's a weight check. The sign has the weight of the aircraft in pounds. The catapult crew guy first shows the presumed weight to the PIC who must give a thumbs up, agreeing, &quot;Yes, that is the weight I believe my aircraft to have.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew guy must then show the same exact set of numbers to the catapult chief operator, who must also approve it: &quot;Yes, the catapult is set to launch that weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can actually see both verifications happening in the two photographs above, the first one is to the PIC, the second to the catapult operator. Only when both verifications have occurred will a launch be permitted.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-03-29T17:49:10.823" LastActivityDate="2016-03-29T17:49:10.823" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26514" PostTypeId="1" AcceptedAnswerId="26515" CreationDate="2016-03-29T17:13:35.107" Score="4" ViewCount="3920" Body="&lt;p&gt;Which materials are used to make the wings and the fuselage of an airliner, for example the Boeing 767 or the Airbus A320?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="3386" LastEditDate="2017-12-29T11:06:49.167" LastActivityDate="2017-12-29T11:06:49.167" Title="What are the wings and fuselage of an airliner made of?" Tags="&lt;airliner&gt;&lt;aerospace-materials&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26515" PostTypeId="2" ParentId="26514" CreationDate="2016-03-29T17:18:42.250" Score="5" Body="&lt;p&gt;Most modern planes are made mostly of &lt;a href=&quot;https://en.wikipedia.org/wiki/6061_aluminium_alloy&quot; rel=&quot;nofollow noreferrer&quot;&gt;aircraft aluminum&lt;/a&gt;. Or at least are skinned in aluminum. The spars and cross members may be made of other materials but I am under the impression they are mainly aluminum as well. Generally high stress areas like wing/fuselage joints may be made of more rigid materials like steel. Aircraft Spruce provides a nice &lt;a href=&quot;http://www.aircraftspruce.com/catalog/mepages/aluminfo.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;break down of the various types of aluminum here&lt;/a&gt;. This answer to a similar question &lt;a href=&quot;https://aviation.stackexchange.com/a/12960/3677&quot;&gt;provides a nice break down&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the technology gets better and the facilities grow in both scale and ability, &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_2.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;composites like carbon fiber have found their place in planes like the 787&lt;/a&gt;. Here is a break down for the 787 &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/odbPo.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/odbPo.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/images/article_04_chart1.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-03-29T17:26:09.177" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26516" PostTypeId="1" CreationDate="2016-03-29T17:40:45.537" Score="2" ViewCount="5118" Body="&lt;p&gt;I want to check the trim condition for aircraft. For this I need the pitching moment coefficient of wing. How to calculate?&lt;/p&gt;&#xA;" OwnerUserId="14239" LastActivityDate="2017-09-29T02:20:21.780" Title="How to calculate the Pitching moment coefficient of wing?" Tags="&lt;pitch&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26517" PostTypeId="1" AcceptedAnswerId="26519" CreationDate="2016-03-29T18:19:05.160" Score="10" ViewCount="1981" Body="&lt;p&gt;Is it possible to recover from a single engine failure at cruising altitude on the HondaJet and safely land the aircraft?&lt;/p&gt;&#xA;" OwnerUserId="14240" LastEditorUserId="14240" LastEditDate="2016-06-02T10:52:21.490" LastActivityDate="2016-06-02T10:52:21.490" Title="Is a single engine failure on the HondaJet recoverable?" Tags="&lt;jet-engine&gt;&lt;accidents&gt;&lt;engine-failure&gt;&lt;single-engine&gt;&lt;hondajet&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26518" PostTypeId="2" ParentId="26491" CreationDate="2016-03-29T18:33:42.403" Score="1" Body="&lt;p&gt;The short answer to this question is to fly ADS-B. If you use ADS-B, then in general, you will always be tracked unless you employ a specific blocking mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than that your only recourse is to always fly under a IFR flight plan which should result in tracking 98% of the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are not getting tracked, it may be because you are using a VFR flight plan, or are flying in an area outside Europe or the United States.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-03-29T18:33:42.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26519" PostTypeId="2" ParentId="26517" CreationDate="2016-03-29T18:34:49.853" Score="13" Body="&lt;p&gt;There would not be much point in having two engines if a single engine failure would be unrecoverable.  In fact, that would make the plane twice as likely to have an unrecoverable event!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one engine has a 1/1million chance of failure, then the chance of failure of at least one of 2 engines is 2-in-a-million.&lt;br&gt;&lt;em&gt;(technically, slightly less than 2-in-a-million... but close enough)&lt;/em&gt;&lt;p&gt;  And if either engine failure is catastrophic, then you've doubled your chances of losing the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know about the HondaJet in particular, but by logic and statistics, I can say that a single engine failure &lt;strong&gt;&lt;em&gt;must&lt;/em&gt;&lt;/strong&gt; be recoverable.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="1696" LastEditDate="2016-03-29T19:55:48.613" LastActivityDate="2016-03-29T19:55:48.613" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="26520" PostTypeId="2" ParentId="26491" CreationDate="2016-03-29T18:47:13.753" Score="5" Body="&lt;p&gt;Tracking sites use FAA data for the most part, augmented by ADS-B data nowadays.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For FAA data, they use what's in the National system. This is usually 99%+ of IFR flight plans, and some VFR flight following flight plans. IFR flights plans that aren't included are those that are local area pop-up requests(staying with the same approach control with a pop-up IFR clearance).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For VFR flights, the only data in the NAS is what's input by controllers for flight following that leaves their airspace(leaving a TRACON headed to a center or another facility, usually; sometimes you can get a NAS code for just a local flight). VFR flight plans sent to and activated by flight service are not sent to ATC, all they are is a tool for rescuers to search for you if you're late and never check in and a search needs to go find you.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-03-29T18:47:13.753" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26521" PostTypeId="1" CreationDate="2016-03-29T19:00:49.560" Score="3" ViewCount="200" Body="&lt;p&gt;I have just spotted &lt;a href=&quot;https://www.flightradar24.com/DLH7TV/93ecc48&quot; rel=&quot;nofollow noreferrer&quot;&gt;something weird&lt;/a&gt; (at least to me) on Flightradar24. A Lufthansa domestic flight from Munich to Frankfurt flying toward... Warsaw in Poland:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b3y6p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b3y6p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My first, and quite obvious conclusion was a Flightradar24 error, as it happens from time to time. But then, I have opened &lt;a href=&quot;https://www.flightradar24.com/flight/lh121&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight LH121 recent details&lt;/a&gt; and to my extreme surprise it turned out, that the very same flight was diverted to Warsaw yesterday as well:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NbG3n.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NbG3n.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any logical, business or technical explanation for this? Is there any logic at all in diverting local, domestic flight to a distant airport in not so close country? Because from mine -- real layman to airline operational rules -- this seems very, very wrong.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, they have like about ten other airports in Germany, about six more in Czech Republic, not mentioning next six or seven in Poland itself, that this plane could land on, before reaching Warsaw.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not mentioning for the fact, that looking at Flightradar24 track it seems like this plane would pointing Warsaw from the very beginning of takeoff. I mean -- Frankfurt is exactly opposite the way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I missing?&lt;/p&gt;&#xA;" OwnerUserId="3230" LastActivityDate="2016-03-29T19:00:49.560" Title="Possible reason for diverting domestic flight to a distant country" Tags="&lt;airline-operations&gt;&lt;commercial-operations&gt;&lt;lufthansa&gt;" AnswerCount="0" CommentCount="11" ClosedDate="2016-03-29T19:34:20.883" ContentLicense="CC BY-SA 3.0" />
  <row Id="26522" PostTypeId="1" AcceptedAnswerId="26545" CreationDate="2016-03-29T19:25:14.550" Score="1" ViewCount="928" Body="&lt;p&gt;Some years ago I have spotted that an Eurolot flight from Amsterdam to Gdansk, diverted close to final approach to a distant airport on the other side of Poland:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UV8hz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UV8hz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this another &lt;a href=&quot;https://aviation.stackexchange.com/q/26521/3230&quot;&gt;example of Flightradar24 bug&lt;/a&gt; and it is more than possible, that this particular flight actually landed in desired destination airport? Or are there any business or operational rules or some special situation, that would judge diverting a plane to a distant airport, while having at least 5-6 other airports closer &quot;on the track&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For me -- layman -- the answer is: &lt;em&gt;No, there are no such reasons and airplane is always diverted to the nearest airport, that is able to accept it (taking plane type, weather conditions etc. into account).&lt;/em&gt; But, I'd like to get some expert confirmation, if there are no exceptions from this rule of thumb?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: &lt;em&gt;In my opinion, we're dealing with a quite different situation here than in &lt;a href=&quot;https://aviation.stackexchange.com/q/26521/3230&quot;&gt;previous question&lt;/a&gt; (and that's why I didn't merged both questions into one). Mainly, because:&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;flight path IMHO is clearly suggesting a diversion, not an error in Flightradar24 and&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;plane's vertical speed is suggesting, that plane is actually landing in the moment, this screenshot was captured, and since I was living in Katowice for over 30 years now, I'm pretty sure, that there was not direct flight on AMS-&gt;KTW route, neither by Eurlot nor by any other airline and neither at the moment of capturing this screenshot nor right now.&lt;/em&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;So there actually was no other flight between Amsterdam and Katowice that Flightradar24 could mistakenly taken as this one&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-04T12:31:22.220" Title="Is it possible to divert a plane to a distant airport?" Tags="&lt;airline-operations&gt;&lt;commercial-operations&gt;" AnswerCount="4" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="26524" PostTypeId="2" ParentId="26516" CreationDate="2016-03-29T20:52:36.520" Score="2" Body="&lt;p&gt;Take the pitching moment coefficient of the wing's airfoil at the trim angle of attack. Since the reference area normally is the wing's area and the reference chord is the wing's mean aerodynamic chord, you do not even need to adjust the number. I hope you have the airfoil polar at hand; if the wing uses several airfoils, take a volume-weighted average; volume being here the product of local area and chord. If the wing has a symmetric airfoil, the coefficient is zero, in most other cases it will be a small negative number.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-03-30T04:22:20.817" LastActivityDate="2016-03-30T04:22:20.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26525" PostTypeId="2" ParentId="26517" CreationDate="2016-03-29T22:53:05.030" Score="-5" Body="&lt;p&gt;Normally, for a dual-engine aircraft to be certifiable, it must be able to fly on a single engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, a single engine failure is very dangerous because the dead engine generates huge drag, so the yaw effect is enormous. In many cases the pilot must reduce the power from the remaining engine to mitigate yaw imbalance, so the aircraft ends up flying at a minimal power which is dangerous. Nevertheless, in most cases if the failure occurs at altitude, there is a good likelihood of being able to land successfully if good flying and procedures are followed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an old joke, &quot;the purpose of the second engine is to fly you to the site of the crash in case of an engine failure&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Contrary to what another answer states, dual engines are not used to provide safety redundancy, they are used to provide more power. As a general rule, aircraft designs with dual engines will usually have greater power, speed and range than comparable single-engine designs. Dual engines are actually more dangerous than single engines because they are more complex to fly and you have double the chances of engine failure.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-03-29T22:53:05.030" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26526" PostTypeId="1" CreationDate="2016-03-30T00:03:46.633" Score="8" ViewCount="1642" Body="&lt;p&gt;If we look at this approach plate it has&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LPV DA&lt;/li&gt;&#xA;&lt;li&gt;LNAV / VNAV DA&lt;/li&gt;&#xA;&lt;li&gt;LNAV MDA&lt;/li&gt;&#xA;&lt;li&gt;CIRCLING&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I understand that if you have WAAS you can shoot the approach to LPV DA minimums. If you have only a GPS with a DME providing lateral navigation you can shoot the LNAV MDA. If you are more than 30 degrees off centerline you shoot the circling. So my question is, how can you shoot the LNAV / VNAV DA on a non-precision GPS approach? Does this require a special GPS that has vertical guidance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y7vdX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y7vdX.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="3825" LastEditDate="2016-03-30T00:24:06.773" LastActivityDate="2018-08-31T00:15:18.493" Title="How do you determine whether you can us LNAV/VNAV minima on an RNAV approach?" Tags="&lt;faa-regulations&gt;&lt;iaps&gt;&lt;terps&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26527" PostTypeId="2" ParentId="26490" CreationDate="2016-03-30T02:38:06.103" Score="1" Body="&lt;p&gt;Lockheed Martin Flight Services (LMFS) provides a history of filed flight plans on their web site under &lt;strong&gt;Flight Planning &amp;amp; Briefing | History&lt;/strong&gt;. The path to the particular page is: &lt;a href=&quot;https://www.1800wxbrief.com/Website/showPilotHistory&quot; rel=&quot;nofollow&quot;&gt;https://www.1800wxbrief.com/Website/showPilotHistory&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, only the last 15 days are available. So if your flight plan is older, it won't be displayed. Additionally, if you're filing your flight plans through a service provider that doesn't provide full LMFS integration (e.g., ForeFlight) it won't be displayed even if within 15 days. In this case, you'll need to refer to your service provider's interface.&lt;/p&gt;&#xA;" OwnerUserId="1968" LastActivityDate="2016-03-30T02:38:06.103" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26528" PostTypeId="2" ParentId="26526" CreationDate="2016-03-30T03:13:53.793" Score="5" Body="&lt;p&gt;The STC documentation provided with the GPS / FMS installation will indicate the type of minima it can go down to.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically, GA aircraft like a Garmin 430/530 will only be certified down to LNAV minima.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Business type aircraft with FMS's may be certified to LNAV/VNAV minima.  These installations use a barometric altitude input to calculate a pseudo glidepath to be displayed.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-03-30T03:13:53.793" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26529" PostTypeId="1" AcceptedAnswerId="26544" CreationDate="2016-03-30T05:43:01.693" Score="4" ViewCount="878" Body="&lt;p&gt;In US, the weather minimums for an alternate airport are typically 600-2 for precision approaches and 800-2 for non-precision approaches at ETA, unless otherwise specified at US Terminal Procedure Publication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it comes when we actually fly the approach, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a) Is the DA raised to 600 for precision approaches?&lt;/li&gt;&#xA;&lt;li&gt;b) Is the MDA raised to 800 for non-precision approaches? &lt;/li&gt;&#xA;&lt;li&gt;c) Is the visibility requirement raised to 2SM for approaches at an airport? &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Do alternate minimums work similar to inoperative components, use of alternate altimeter settings, NOTAM to change the actual minimums we use to fly, or a purely preflight planning number for selecting alternate airport? &lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-03-30T06:16:10.237" LastActivityDate="2016-03-30T12:57:55.357" Title="When an alternate minimum applies, does it change MDA or DA?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;approach&gt;&lt;ifr-navigation&gt;&lt;non-precision-approach&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26530" PostTypeId="1" CreationDate="2016-03-30T06:58:00.393" Score="11" ViewCount="3426" Body="&lt;p&gt;WWII RAF fighters had a loop on top of the joy stick in case of hand loss or injury - Anyone know why the Allies didn't copy this very helpful idea?&lt;/p&gt;&#xA;" OwnerUserId="14243" LastEditorUserId="19" LastEditDate="2016-10-25T15:10:13.307" LastActivityDate="2020-05-05T17:01:13.823" Title="Why was the WWII RAF fighter joy stick loop design not used widely?" Tags="&lt;aircraft-performance&gt;&lt;emergency&gt;&lt;flight-instruments&gt;&lt;cockpit&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26531" PostTypeId="1" CreationDate="2016-03-30T07:12:49.007" Score="4" ViewCount="321" Body="&lt;p&gt;This question is specific to Bombardier C-Series aircraft which  has three modes: Flight control computer normal mode, FCC Direct mode and REU direct mode:&#xA;(I am not sure if other aircraft have an intermediate mode before switching to alternate law)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Control law gains are computed for both FCC normal and FCC direct mode even if the computer is in normal mode. Direct mode commands are outputted when the switch happens from normal to direct.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fly By Wire Flight control computer switches from normal law to alternative law under certain conditions (when minimum required sensor set is lost for instance). &#xA;So I assume the control laws are also switched from normal to direct. &#xA;Are the direct mode control gains computed and monitored when the flight control system is under normal law?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="11517" LastEditDate="2016-03-30T12:40:55.063" LastActivityDate="2016-03-30T12:40:55.063" Title="Are direct law command gains monitored for correctness when flight control computer is in normal mode?" Tags="&lt;fly-by-wire&gt;&lt;bombardier&gt;&lt;airbus-a220&gt;" AnswerCount="0" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26532" PostTypeId="1" AcceptedAnswerId="26892" CreationDate="2016-03-30T08:09:10.403" Score="8" ViewCount="4052" Body="&lt;p&gt;I have read that is to help the flow remains attached, but I do not understand the physical principle.&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="5517" LastEditDate="2016-04-13T15:31:29.387" LastActivityDate="2018-09-19T15:57:44.353" Title="Why should the leading edge be blunt on low-speed, subsonic airfoils?" Tags="&lt;aerodynamics&gt;&lt;airfoil&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26533" PostTypeId="1" CreationDate="2016-03-30T08:23:39.470" Score="9" ViewCount="3519" Body="&lt;p&gt;In the next picture what are the items circled in red?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TkRVR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TkRVR.jpg&quot; alt=&quot;747 undercarriage&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Undercarriage.b747.arp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Photographed by Adrian Pingstone in August 2002 and released to the public domain.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="1289" LastEditDate="2016-03-31T13:35:59.313" LastActivityDate="2016-03-31T13:35:59.313" Title="What are those in the belly of a 747?" Tags="&lt;boeing-747&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26534" PostTypeId="2" ParentId="26533" CreationDate="2016-03-30T08:51:59.250" Score="4" Body="&lt;p&gt;The forward inlets are air inlets for the air conditioning and pressurisation.&#xA;I am not sure of the after ringed area.&lt;/p&gt;&#xA;" OwnerUserId="14127" LastEditorUserId="753" LastEditDate="2016-03-30T11:15:39.150" LastActivityDate="2016-03-30T11:15:39.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26535" PostTypeId="2" ParentId="26533" CreationDate="2016-03-30T08:59:08.067" Score="11" Body="&lt;p&gt;The forward ones are a ram air inlet (NACA duct) for the Environmental conditioning System (ECS) and what looks like an antenna. The aft one is an exit louver for the ECS.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="1467" LastEditDate="2016-03-30T10:06:29.687" LastActivityDate="2016-03-30T10:06:29.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26536" PostTypeId="1" CreationDate="2016-03-30T09:46:13.100" Score="20" ViewCount="7648" Body="&lt;p&gt;As I understand the procedure for go-around it includes retracting the flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The decision to make a go-around must sometimes be made quickly, under stressful conditions, like in bad weather. Retracting flaps introduces one more thing to do under sometimes stressful conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speed is low during landing and by retracting flaps you give away safety margin for lift. (Speed may also slow further since the nose is raised during go-around.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Retracting flaps may also affect pitch and thereby make control of the aircraft slightly more difficult in a situation which may already be stressful.&lt;/p&gt;&#xA;" OwnerUserId="14245" LastEditorUserId="14245" LastEditDate="2016-03-30T10:44:39.257" LastActivityDate="2016-07-12T15:30:23.610" Title="Why retract flaps at go-around?" Tags="&lt;flaps&gt;&lt;go-around&gt;" AnswerCount="6" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26537" PostTypeId="2" ParentId="26536" CreationDate="2016-03-30T10:04:59.700" Score="-2" Body="&lt;p&gt;Flaps change the wing properties and thereby changes the lift, the approach attitude and lowers the stall speed (all landings are basically controlled stalls). If you need to get out of trouble quickly in a go-around then you may need all the energy that you can get, retracting the flaps changes the wing back to the efficiency of take off to allow you to climb out of trouble.&lt;/p&gt;&#xA;" OwnerUserId="14127" LastEditorUserId="14127" LastEditDate="2016-03-30T11:21:47.743" LastActivityDate="2016-03-30T11:21:47.743" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26538" PostTypeId="2" ParentId="26536" CreationDate="2016-03-30T10:44:26.937" Score="31" Body="&lt;p&gt;For the same reason that you don't takeoff with full flaps. Because the climb performance sucks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flaps do add lift, but also a lot of drag. A low flap setting often provides more lift than drag, assisting climbout, whereas full flap offers a whole lot of drag, which is desirable when you want to be slow for landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But a go-around necessitates gaining height quickly, which will not work with landing flap selected. The usual procedure, at least in light aircraft, is to wait until the vertical speed is neutral or positive before retracting flap. This minimises some of the risks you've raised about aircraft control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is often said that a go-around is a period of heavy workload, and managing the flaps and airspeed &lt;a href=&quot;https://www.atsb.gov.au/publications/investigation_reports/2012/aair/ao-2012-116/&quot;&gt;is not easy&lt;/a&gt;. That is why the go-around is a fundamental procedure taught right from the very beginning, and practiced and tested regularly. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-03-30T10:44:26.937" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26539" PostTypeId="2" ParentId="26536" CreationDate="2016-03-30T10:55:33.363" Score="3" Body="&lt;p&gt;Retracting flaps on a go around is not done until a positive climb rate is attained. And even then it should be done incrementally as airspeed picks up. The specific checklist varies among planes, but generally speaking you throttle up, remove carb heat, attain a positive climb rate, (raise landing gear if it is retractable), remove one click of flaps, wait for speed to increase, remove more flaps, wait for speed increase, rinse and repeat...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A go around isn't unlike a takeoff, you want to be climbing as fast as possible, shedding the drag caused by the flaps allows you to pick up speed faster, resulting in a safer climb. But, you can't just fully retract the flaps immediately because they are providing significant lift, you could slam into the ground if you aren't climbing or if you reduce flaps too quickly. There is also the danger of stalling if you reduce flaps before your speed has picked up sufficiently. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastEditorUserId="753" LastEditDate="2016-03-30T11:24:10.527" LastActivityDate="2016-03-30T11:24:10.527" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26540" PostTypeId="2" ParentId="26536" CreationDate="2016-03-30T11:10:03.840" Score="11" Body="&lt;p&gt;You correctly point out some of the challenges surrounding the procedure of retracting flaps upon go-around. Go arounds can be a stressful situation, flaps do give additional lift and margin against a stall, and retracting them does result in a pitch change for which the pilot must compensate. Allow me to address each of these concerns in turn.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A go-around can be a stressful situation—especially, as you point out, if additional concerns such as weather come into play. Outside of the training environment, a go around is usually executed because some aspect of the landing is not right, whether that be the pilot, the airplane, the weather, the runway, other traffic, or any combination of those or numerous other conditions. All of these can add up to create a very demanding situation indeed. For this reason, the go-around procedure is carefully taught and practiced often in primary training, and pilots continue to practice and demonstrate it throughout their career. Now, raising the flaps is a normal configuration change that experienced pilots are used to making. Even in demanding situations, raising the flaps should not make an excessive demand on the pilot's attention. This includes already demanding situations such as during a go-around.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airspeed is a major consideration during go-around. Flaps do give additional margin above the stall, some designs more than others. A go-around is all about transitioning from the low-speed approach to the generally higher speed climb out. Thus, the aircraft will be accelerated, typically to the best rate of climb speed (&lt;a href=&quot;https://en.wikipedia.org/wiki/V_speeds#Regulatory_V-speeds&quot;&gt;Vy&lt;/a&gt;). Typical go-around procedure will call for retracting the flaps once the aircraft is stabilized with sufficient speed, thus reducing—if not eliminating—the risk associated with reduced margin above stall. Even then, the flaps should typically be retracted slowly and in stages, allowing for the speed to increase appropriately. Putting all this together, proper flap retraction during a go-around will not result in excessive risk exposure due to airspeed consideration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Retracting the flaps does result in a pitch change, though different types of flap designs will result in different amounts of change at different rates. Again, the pilot should be experienced and practiced in compensating for this change. Again, since the flaps will typically be retracted slowly and/or in stages, the pilot will be able to compensate throughout the retraction process. During the go-around, the pilot is already making numerous pitch changes and compensations as power, airspeed, and lift change; compensating for flap induced pitch change is part of the expected process.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Now, your question was why &lt;em&gt;should we&lt;/em&gt; retract the flaps during a go-around. I have addressed your valid concerns above. Now allow me to give a some reasons why retracting the flaps is advisable or necessary.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Flaps reduce climb rate. Flaps add drag which is a good thing for landing, but not good for the climb. In retracting the flaps, the aircraft is configured for its best possible climb performance. Some aircraft have such limited performance that they simply will not climb with full flaps, even at typical elevations and in typical weather. At high elevations and in hot weather, most aircraft will have substantially diminished ability to climb with full flaps.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Each type of aircraft has a speed limit for how fast the aircraft is allowed to go with flaps extended (&lt;a href=&quot;https://en.wikipedia.org/wiki/V_speeds#Regulatory_V-speeds&quot;&gt;Vfe&lt;/a&gt;). This is for structural considerations so that the flaps and wings are not damaged by excessive speed. Retracting the flaps allows for acceleration to climb speed and above without the risk of overspeed damage to the flaps. It is very possible, in some aircraft, to overspeed the flaps after the go-around if they are not retracted soon enough.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For multi-engine aircraft, having the flaps retracted typically puts the aircraft in the best configuration to handle an engine failure emergency. If one of the engines fail, the aircraft will climb best on the power of the remaining engine(s) with the flaps retracted.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-03-30T11:10:03.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26542" PostTypeId="1" AcceptedAnswerId="26558" CreationDate="2016-03-30T11:34:18.903" Score="8" ViewCount="527" Body="&lt;p&gt;As I understand it, pressurization cycles introduce the most stress on an airframe so maintenance intervals are tied to it. However, not all planes are equal in that regard, a long haul flight in a 747 might easily take 10 hours counting for one pressurization cycle while a 737 can do 6 trips in that time. Are short-haul planes build &quot;sturdier&quot; in this regard than their long-haul counterparts so that they are able to better cope with the amount of stress? And/or do they have to go into maintenance more often?&lt;/p&gt;&#xA;" OwnerUserId="7735" LastEditorUserId="19" LastEditDate="2016-10-14T13:42:55.220" LastActivityDate="2016-10-14T13:42:55.220" Title="What are the structural differences between short- and long-haul airplanes?" Tags="&lt;aircraft-design&gt;&lt;airframe&gt;&lt;short-haul&gt;&lt;long-haul&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26543" PostTypeId="1" AcceptedAnswerId="27096" CreationDate="2016-03-30T12:49:59.300" Score="8" ViewCount="803" Body="&lt;p&gt;I'm an early solo glider pilot, with the long term goal of also obtaining a PPL (not a LAPL(A)).  I am planning to do this after I have obtained at least my bronze badge, which I aspire to within the next twelve months.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Originally I thought that the only route open to me was to do the full PPL.  My understanding was that I can get a credit of 10% of P1 hours on a glider deducted from the requirements (max 10 hrs), however the CAA website refers to holders of &quot;a pilot’s licence for another type of aircraft, except balloons&quot;.  I'm not sure if that applies to a bronze holder or if I would need to obtain a LAPL(S) or SPL for them to count (for which I would presumably need a bronze XC endorsement to make the required XC flight).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I obtain a LAPL(S), then according to the CAA I can add a TMG rating (6+ hrs) and then, after hours building (24hrs) do a conversion course (15+ hrs) to the full PPL(A).  It's not clear if this route is available if I obtained an SPL, although for a fee I believe you can swap licences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can P1 hours as a glider pilot count towards a PPL(A) without obtaining a LAPL(S)/SPL?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the LAPL(S) -&gt; TMG -&gt; PPL route viable? Would I need to go to an &quot;ATO&quot; for TMG training or can my local gliding club do this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aside from just doing a PPL from scratch, are there any other viable routes that I've missed (e.g. via a LAPL(A) on a TMG somehow)?&lt;/p&gt;&#xA;" OwnerUserId="14246" LastEditorUserId="62" LastEditDate="2016-03-30T13:06:10.917" LastActivityDate="2016-04-21T21:45:31.170" Title="What PPL routes are available with gliding experience?" Tags="&lt;easa-regulations&gt;&lt;caa-uk-regulations&gt;&lt;sailplane&gt;&lt;lapl&gt;&lt;tmg&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26544" PostTypeId="2" ParentId="26529" CreationDate="2016-03-30T12:57:55.357" Score="4" Body="&lt;p&gt;From the FAA Instrument Procedures Handbook, section 6-4: &quot;The 600-2 and 800-2 rules, or any exceptions, only apply to flight planning purposes, while published landing minimums apply to the actual approach at the alternate.&quot;&lt;/p&gt;&#xA;" OwnerUserId="2696" LastActivityDate="2016-03-30T12:57:55.357" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26545" PostTypeId="2" ParentId="26522" CreationDate="2016-03-30T13:08:35.427" Score="6" Body="&lt;p&gt;The diversion airport is selected by the captain¹.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft needs to divert for some urgent reason like engine failure, smoke/suspected fire/fire, medical emergency and similar, the captain will select the airport so that they can land as soon as possible. However from cruise altitude even expedient descent still takes about 15–30 minutes and the plane can cover 50–100 nmi, so they still have some choice in most places, especially densely populated areas like Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But there are many less urgent reasons that warrant diversion. The most common is of course that the intended destination is closed due to weather, accident or other problem. And then there are problems like pressurization failure that require descent to lower altitude where the fuel consumption is higher, so the plane no longer has enough fuel to reach the original destination, but still has fuel to fly considerable distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes the plane can even reach the intended destination just fine, but some fault occurs that would be hard to fix there, so the plane returns or diverts somewhere it will be easier to fix.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In these cases, the captain calls the airline dispatching (over radio, HF radio or satellite phone) and discusses with them where they should divert to make least disruption to the overall airline operations considering things like ability to fix the diverting plane, availability of replacement plane or alternate connections for the passengers, availability of replacement crew to fly the replacement plane or this plane after it is fixed, availability of airline representatives to take care of the passengers and many other things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So something happened and for some operational reason it was easier for the airline if they had the plane in Krakow than if they had it in Gdansk (or, if it was not possible to have it in Gdansk, better to have it in Krakow than, say, Warsaw, which was still closer). For example I remember reading about incident where wind shield cracked on a plane already on approach to their destination, Klagenfurt, and they returned to Vienna and sent the passengers by bus. Because it was apparently easier (and cheaper) for the airline than fixing the airplane in Klagenfurt without suitable hangar (with cracked winshield the plane may complete the flight, but not take off again).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Except really special circumstances like violation of foreign airspace and arrest by interceptors, nobody from outside can divert the plane. The pilots do.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-03-30T13:15:38.043" LastActivityDate="2016-03-30T13:15:38.043" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26546" PostTypeId="2" ParentId="26530" CreationDate="2016-03-30T15:44:24.997" Score="27" Body="&lt;p&gt;A control stick with a loop at the top was called a &quot;Spade Stick&quot;.  Generally only Hurricanes and Spitfires had them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cockpits on these aircraft were small and it was a problem for the control column to get full travel for roll control. This was solved by making the control column rotate at about mid-stick instead of from the the floor. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other aircraft didn't use them because the cockpits were large enough to accommodate a normal stick and still provide good leverage and side to side travel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The loop was there so a pilot could use both hands on the stick to get more lateral force since the effective length of the stick was now much less than a conventional floor mounted control stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots found them to be much more comfortable to hold and loop style sticks did also get used some on larger aircraft with conventional floor mounted control sticks.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Full right aileron&#xA;&lt;a href=&quot;https://i.stack.imgur.com/3ZHWl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3ZHWl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-10-26T11:13:38.117" LastActivityDate="2016-10-26T11:13:38.117" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26547" PostTypeId="1" CreationDate="2016-03-30T16:08:04.443" Score="1" ViewCount="281" Body="&lt;p&gt;For propellers, as the airspeed increases thrust decreases. Is the airspeed component taken as a vector quantity perpendicular to the propeller? If that's true, then it's quite easy to visualize in the case of airplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for quadcopters can the forward component of the thrust vector of a quadcopter type rotor be expressed as:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$&#xA;V_q\cdot{sin}\theta_t&#xA;$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;$V_q$ is the forward airspeed of the quadcopter, and&lt;/li&gt;&#xA;&lt;li&gt;$\theta_t$ is the angle of rotor tilt&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is this an accurate expression of the thrust vector?&lt;/p&gt;&#xA;" OwnerUserId="14248" LastEditorUserId="9012" LastEditDate="2016-03-31T20:23:41.997" LastActivityDate="2016-03-31T23:35:47.240" Title="How is propeller thrust vector accurately expressed for airplanes and multirotors?" Tags="&lt;propeller&gt;&lt;aircraft-physics&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-04-01T10:29:38.717" ContentLicense="CC BY-SA 3.0" />
  <row Id="26548" PostTypeId="1" CreationDate="2016-03-30T17:26:54.400" Score="7" ViewCount="501" Body="&lt;p&gt;What action does the flight control computer take (under normal law) when it realizes, for instance, &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Inboard actuator of aileron/elevator disengaged or &lt;/li&gt;&#xA;&lt;li&gt;There is a disconnect between the LVDT and the actuator &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Is there any backup for this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any minimum control requirements established for the flight control computer to 'arm' or 'enable' the &quot;backup&quot; if available ?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="3504" LastEditDate="2016-04-20T16:42:27.070" LastActivityDate="2016-11-20T18:30:12.927" Title="How does a flight control computer deal with control surface disengagement?" Tags="&lt;flight-controls&gt;&lt;fly-by-wire&gt;&lt;control-surfaces&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26549" PostTypeId="1" AcceptedAnswerId="26551" CreationDate="2016-03-30T19:03:53.223" Score="30" ViewCount="54951" Body="&lt;p&gt;When the tower controller, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_terminal_information_service&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATIS&lt;/a&gt; or a &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow noreferrer&quot;&gt;METAR&lt;/a&gt; says &lt;em&gt;Wind 270, 15 knots&lt;/em&gt; does it mean the wind is blowing in the westward or in the eastward direction?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a single convention used to express the wind direction?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-16T09:01:48.867" LastActivityDate="2020-04-30T18:27:52.730" Title="How is wind direction reported (blowing from or blowing to)?" Tags="&lt;air-traffic-control&gt;&lt;wind&gt;&lt;metar&gt;&lt;atis&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26550" PostTypeId="2" ParentId="26549" CreationDate="2016-03-30T19:07:59.463" Score="18" Body="&lt;p&gt;Wind numbers say where the wind is coming from. Wind 270 means that the wind is coming from the west, and blowing towards the east. If you point west (270), you will have the wind in your face as a headwind. If you point east (270 - 180 = 90), you will have a tailwind, or the wind at your back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to think about this is if you want to take off from runway 27, where you are pointing to 270, (pointing west), you want the wind coming from 270, so that you have a headwind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's easy to remember that when you are on runway 27 you are pointing to 270. Just remember that a headwind aligned with the runway will have the same number, and you will remember that the wind direction is where it is coming from.&lt;/p&gt;&#xA;" OwnerUserId="639" LastEditorUserId="639" LastEditDate="2016-03-30T19:13:07.450" LastActivityDate="2016-03-30T19:13:07.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26551" PostTypeId="2" ParentId="26549" CreationDate="2016-03-30T19:13:58.063" Score="29" Body="&lt;p&gt;As far as METARs are considered, the wind direction gives the direction &lt;em&gt;from which&lt;/em&gt; the wind is coming. From &lt;a href=&quot;http://www.met.tamu.edu/class/metar/metar-pg6.html#Wind%20Definitions&quot; rel=&quot;noreferrer&quot;&gt;METAR definitions&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Wind Direction.&lt;/p&gt;&#xA;&lt;p&gt;The direction, in tens of degrees, from which the wind is blowing with reference to true north.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;So, Wind 270 shows that the wind is coming from west.&lt;/p&gt;&#xA;&lt;p&gt;The reporting in ATIS and tower is the same, only difference being that the reference is magnetic north, while it is true north for METAR.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-03-30T19:13:58.063" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26553" PostTypeId="1" CreationDate="2016-03-30T20:19:35.100" Score="3" ViewCount="735" Body="&lt;p&gt;In simple words, what are LNAV, VNAV, and BARO-NAV?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they all precision approaches and will they cancel the traditional approaches?&lt;/p&gt;&#xA;" OwnerUserId="14251" LastEditorUserId="167" LastEditDate="2016-04-06T21:22:39.640" LastActivityDate="2016-04-06T21:22:39.640" Title="In simple terms, what are LNAV, VNAV, and Baro-VNAV approaches?" Tags="&lt;terminology&gt;&lt;approach&gt;&lt;instrument-procedures&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-04-07T07:04:23.087" ContentLicense="CC BY-SA 3.0" />
  <row Id="26554" PostTypeId="1" AcceptedAnswerId="26571" CreationDate="2016-03-30T20:45:33.913" Score="3" ViewCount="270" Body="&lt;p&gt;Is an &lt;a href=&quot;https://www.acrartex.com/products/catalog/elts-general-aviation/me406-ace-elt/&quot; rel=&quot;nofollow&quot;&gt;Emergency locator transmitter - ELT&lt;/a&gt; required on any type of aircraft carrying passengers over water? Does it need to be fitted with an &lt;a href=&quot;http://www.cmhammar.com/products/onboard/h20/epirbs/&quot; rel=&quot;nofollow&quot;&gt;hydrostatic release unit&lt;/a&gt; so that it doesn't sink with the aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If they don't carry a releasable ELT, how are aircraft planned to be located after an accident over the ocean?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;References to regulatory documentation definitely a plus (e.g. for the US, or for island countries like Australia or New Zealand).&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-03-31T10:39:00.690" Title="Is a releasable locator beacon (ELT) required for aircraft carrying passengers over a water area?" Tags="&lt;regulations&gt;&lt;search-and-rescue&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="26555" PostTypeId="2" ParentId="25089" CreationDate="2016-03-30T22:09:57.997" Score="13" Body="&lt;p&gt;Mark is right when he says that there is no induced drag at supersonic speeds, but it is an invitation for misunderstandings. Induced drag is replaced by lift wave drag, and all what happens is that aerodynamicists choose to use two different names for basically the same effect: Air gets pushed down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As usual when I post a long answer, I was not quite happy with the existing answer(s). Now I have some time and try to give a better answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, why does the straight wing work better only at very high Mach numbers (&gt; 2.0)? Because at lower supersonic speed a swept wing gives overall better performance. The sweep angle $\varphi_0$ must be high enough to allow for a subsonic leading edge (Mach &amp;lt; $\frac{1}{cos\varphi_0}$). Then the flow around the leading edge is subsonic and creates a suction area when accelerating around the nose contour. This suction helps to reduce drag - after all, this same suction is why a subsonic airfoil in inviscid flow has no drag. Edward C. Polhamus did a lot of research on this at NACA Langley and published &lt;a href=&quot;http://www.pdas.com/refs/tp1500.pdf&quot; rel=&quot;noreferrer&quot;&gt;several papers with equations for calculating the suction force&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you fly faster than Mach 2, the sweep angle for a subsonic leading edge rapidly gets too high for acceptable subsonic flight, and an unswept wing becomes the better alternative since you need to accept a supersonic leading edge. Examples are the wing of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;noreferrer&quot;&gt;F-104&lt;/a&gt; or the canard of the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;XB-70&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now for the airfoil drag at supersonic speed. Because it is easiest to explain, I select a rhombic cross section:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0lYfR.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0lYfR.png&quot; alt=&quot;Rhombic airfoil in symmetric supersonic flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rhombic airfoil in supersonic flow at zero angle of attack (own work). The plus sign denotes higher pressure, the minus sign lower pressure than ambient. By selecting a rhombic airfoil, the flow is very easy to determine because the pressure only changes &lt;a href=&quot;https://aviation.stackexchange.com/questions/12001/what-causes-the-reduction-in-speed-across-the-shockwave/12003#12003&quot;&gt;when the local contour gradient changes&lt;/a&gt;. The two compression shocks create the typical sonic boom when arriving at the ground. Note that this airfoil already creates pressure drag even at zero lift. Any airfoil thickness greater than zero and any airfoil camber will cause this type of drag where the forward-facing areas see higher pressure and the rear-facing areas experience suction. This type of drag is called wave drag. It can only be minimized by minimizing the relative thickness of whatever is supposed fly at supersonic speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the angle of attack is increased, this airfoil begins to create lift. Now the compression by the lower forward shock becomes stronger and that by the upper forward shock becomes weaker. The expansion fan is the same again on both sides, so the upper rear half experiences less pressure than the lower rear half. I tried to symbolize this by the amount of plus and minus signs:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PKF2m.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PKF2m.png&quot; alt=&quot;Rhombic airfoil in supersonic flow at an angle&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the pressure difference is constant over chord, so the center of pressure is at 50% of chord length. Note also that the lift vector is perpendicular to the chord line. Since lift is defined as the force perpendicular to the direction of the undisturbed air, supersonic lift always carries a drag component which is proportional to the angle of attack - there is no suction at the nose to alleviate this! The wave drag of the airfoil at zero angle of attack still comes on top, so we have a shape-dependent wave drag and a lift-dependent wave drag component. This lift-dependent wave drag replaces the induced drag of subsonic speeds. If we compare the magnitude of both, we find:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Subsonic: $c_{Di} = \frac{c^2_L}{\pi\cdot AR\cdot\epsilon}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Supersonic formula for 2D flow: $c_{{DW}_L} = c_L\cdot\alpha$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't look so similar, so let's now express the angle of attack $\alpha$ by the lift coefficient divided by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/14508/calculating-a-finite-wings-lift-from-its-sectional-airfoil-shape/14559#14559&quot;&gt;lift curve slope&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\alpha = \frac{c_L}{c_{L\alpha}} = \frac{c_L}{\frac{4}{\sqrt{Ma^2-1}}\cdot\left(1 - \frac{\lambda}{2\cdot AR\cdot\sqrt{Ma^2-1}}\right)}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the lift wave drag component becomes $c_{{DW}_L} = \frac{c^2_L}{\frac{4}{\sqrt{Ma^2-1}}\cdot\left(1 - \frac{\lambda}{2\cdot AR\cdot\sqrt{Ma^2-1}}\right)}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's compare the F-104 wing, which has an aspect ratio $AR$ of 2.45 and a taper ratio $\lambda$ of 0.385: If we plug in the parameters and adjust $\epsilon$ such that both sub- and supersonic lift-dependent drag coefficients agree, $\epsilon$ would need to be 0.89 at Mach 1.2, 0.58 at Mach 1.4 and 0.31 at Mach 2.0. The dramatic rise of lift wave drag over Mach is caused by the reduction in the lift curve slope over Mach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For slender bodies the lift curve slope is $c_{L\alpha} = \frac{\pi\cdot AR}{2}$ and the lift wave drag component becomes $c_{{DW}_L} = 2\cdot\frac{c^2_L}{\pi\cdot AR}$. For slender bodies the supersonic $\epsilon$ is 0.5, regardless of Mach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The important conclusions from this for wing selection are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Sweep does no longer help once the leading edge is supersonic.&lt;/li&gt;&#xA;&lt;li&gt;Lift wave drag continues where induced drag drops off. Lift always causes drag.&lt;/li&gt;&#xA;&lt;li&gt;For a supersonic wing the aspect ratio is of minor importance.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Now back to the original question: Once the leading edge is supersonic, sweep is no longer helpful. Now the best wing is straight, because it will need the lowest wing area to create the required lift at subsonic speed. At supersonic speed its lower area will translate into lower friction drag, making it better than comparable delta or swept wings.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2017-04-01T11:09:37.883" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26556" PostTypeId="2" ParentId="13257" CreationDate="2016-03-30T22:25:16.583" Score="5" Body="&lt;p&gt;There are many engineering factors that determine g ratings.  The cumulative fatigue damage from dominant operations primarily determine g-ratings.  When landing, this contributes heavy fatigue positive g's.  When flying, the natural forces of gravity and turbulence (to include gusting winds) contribute to fatigue damage.  These stresses are felt throughout the control systems.  Therefore, the plane is engineered to be stronger in all its considerations to support and counter the greater fatigue concerns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://adg.stanford.edu/aa241/structures/structuraldesign.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://adg.stanford.edu/aa241/structures/structuraldesign.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How come V-n diagrams are not symmetric?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;V-n Diagrams tend to visually reflect some of the more dominant fatigue considerations.  Engineered considerations that influence g ratings also are reflected in the V-n Diagrams for similar reasons. Notice the sharp changes in shape in the following Vn diagram and its explanations:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://adg.stanford.edu/aa241/structures/vn.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://adg.stanford.edu/aa241/structures/vn.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why not strengthen everything to have higher g limits? Cost and useful return on investment.  There is little practicality to have an aircraft stressed to +/- 100 g's if it has little useful load, is too heavy to fly, or costs so much very few customers can afford buying it and pay for its operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Balances in weight, cost, strength... are in constant flux throughout design to provide an overall useful and affordable aircraft.  Equal g ratings is not a priority, however, meeting regulatory minimums is a priority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/air/directorates_field/small_airplanes/media/CPS_Part_23.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/air/directorates_field/small_airplanes/media/CPS_Part_23.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are normal and abnormal conditions in which an airplane is stressed for negative g's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normal negative g's include: in-flight turbulence, recovery from a bounced landing, down drafts / wind shear ... and other engineered limits that are reflected in negative g ratings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Abnormal negative g's include: walking on or otherwise loading the top of a wing, unrated aerobatics, excessive snow loading while parked, excessive pilot induced control moments causing negative g's, excessive road bumps while in transport ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conditions violating negative g design considerations include: improperly secured or excessively worn folding wing hardware, worn or warped wing gusset or related fastening hardware, fatigued or weak weldments, corrosion ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;G-ratings have to do with Damage Tolerance&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a point of reference.  Fatigue failures are usually more significant at gross weight, and therefore &lt;strong&gt;utility&lt;/strong&gt; and &lt;strong&gt;ultimate&lt;/strong&gt; g ratings (regulatory) are usually given at gross weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Strength of Materials is a particular area of science and engineering that characterizes properties of materials, including fatigue.  Computer simulations can run thousands of tests using variations in parameters to anticipate fatigue failures before they actually occur in flying aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft can be engineered to have greater negative g limits than positive g limits; however the cost for this non-useful engineered feature would likely be unacceptable to customers.  Lower useful weight to have the higher negative g support structure as an example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How come planes can endure more positive than negative g's?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the FAA over many years of experience has set standards for minimum g ratings to help control accident outcomes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example, see Part 25 AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES&#xA;Subpart C--Structure Fatigue Evaluation&#xA;Sec. 25.571&#xA;Damage-tolerance and fatigue evaluation of structure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://lessonslearned.faa.gov/Comet1/25.571.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://lessonslearned.faa.gov/Comet1/25.571.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and an A/P's insights under the following debrief:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/files/gslac/library/documents/2011/Jul/55585/FLYING%20LESSONS%20110623.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.faasafety.gov/files/gslac/library/documents/2011/Jul/55585/FLYING%20LESSONS%20110623.pdf&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In terms of engineering to meet regulatory requirements, the cumulative probability of fatigue failure resulting from negative g's is less than the cumulative probabilities of fatigue failure from positive g's.  The design limits reflect these failures through probability equations relating likeliness to occur and level of impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAA SYSTEM SAFETY ANALYSIS AND ASSESSMENT (acceptable methods) &#xA;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1309-1E.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2023.1309-1E.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Methods of working probability equations:&#xA;&lt;a href=&quot;http://people.qatar.tamu.edu/shehab.ahmed/ecen_459/Lec34-37.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://people.qatar.tamu.edu/shehab.ahmed/ecen_459/Lec34-37.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The information provided in these links are to show the effort involved is no small task for aircraft designers.  Many thousands of failure modes accumulate when every part, joint, human error, environmental, and every other factor potentially part of a failure is considered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So when asking a designer what the effect would be on g-rating based on a specific failure mode of a part, is not a reasonable question to ask because of the extensive interactions with the total system to be considered.&lt;/p&gt;&#xA;" OwnerUserId="14253" LastEditorUserId="14253" LastEditDate="2017-03-15T17:17:04.313" LastActivityDate="2017-03-15T17:17:04.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26557" PostTypeId="2" ParentId="25231" CreationDate="2016-03-30T22:32:08.813" Score="0" Body="&lt;p&gt;To add to the above, in all carbureted A/C dew point is needed for indication of carburetor icing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dew Point relative to temperature is a useful indication of weather conditions .&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-03-30T22:32:08.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26558" PostTypeId="2" ParentId="26542" CreationDate="2016-03-30T22:37:47.650" Score="8" Body="&lt;p&gt;Yes, short range airliners are designed for up to 90.000 cycles whereas long range airliners can be designed for 40.000 cycles or less. And it is not only the pressurized cabin that needs to be designed for more load cycles, also the landing gear has a lot more work to do. This should become clear when you calculate how many miles/kilometers an airplane will taxi in its life and compare that to the design life of a regular car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your average short range airliner will easily taxi 5 times more miles in its life than your average car will drive.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-03-30T22:37:47.650" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26559" PostTypeId="1" AcceptedAnswerId="26561" CreationDate="2016-03-30T23:07:32.207" Score="23" ViewCount="4549" Body="&lt;p&gt;If a pilot is trying to complete 3 day or night landings every 90 days in a multi-engine aircraft in order to be multi-engine current per FAA requirements, can those landings be done in a Simulator or a Flight Training Device?&lt;/p&gt;&#xA;" OwnerUserId="14254" LastActivityDate="2016-03-31T20:33:18.483" Title="Do Landings in a Simulator Count Towards Landing Currency? (FAA in the USA)" Tags="&lt;faa-regulations&gt;&lt;currency&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26561" PostTypeId="2" ParentId="26559" CreationDate="2016-03-31T00:33:44.807" Score="30" Body="&lt;p&gt;Yes, as long as the simulator is properly certified (to level B,C,or D) you can do your takeoffs and landings to regain currency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long haul airline pilots frequently have trouble staying current for 3 takeoffs and landings in 90 days. This is because it takes 4 pilots to complete a long haul flight but only 1 will get the takeoff and landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;3 trips a month is about all you do, and if you are scheduled to be the augment pilot, you don't get a takeoff and landing.      &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-03-31T20:33:18.483" LastActivityDate="2016-03-31T20:33:18.483" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26562" PostTypeId="2" ParentId="26559" CreationDate="2016-03-31T00:39:06.010" Score="19" Body="&lt;p&gt;It can be done. As mentioned &lt;a href=&quot;https://www.nbaa.org/ops/safety/in-flight-safety/night/Part61-Sect61-57.php&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) The takeoffs and landings required by paragraph (b)(1) of this&#xA;  section may be accomplished in a flight simulator that is—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Approved by the Administrator for takeoffs and landings, if the&#xA;  visual system is adjusted to represent the period described in&#xA;  paragraph (b)(1) of this section; and&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Used in accordance with an approved course conducted by a&#xA;  training center certificated under part 142 of this chapter.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The regulation is &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/61.57&quot;&gt;14 CFR 61.57&lt;/a&gt;. For more details, you can read &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2061-98B.pdf&quot;&gt;this AC&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-03-31T00:39:06.010" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26563" PostTypeId="2" ParentId="12563" CreationDate="2016-03-31T02:53:48.787" Score="0" Body="&lt;p&gt;Another important consideration is each planned OR potential stop for the aircraft (potential meaning a diversion or extra stop for fuel, maintenance, weather or passenger issues such as illness). Any passenger boarding an international flight must have all the appropriate documentation for both entry AND exit for stops even if they are to remain aboard while some other passengers enplane or deplane. The reason is, so that a person is not arrived physically in a destination they have no proper credentials for (EX: a VISA or passport or both)&lt;/p&gt;&#xA;" OwnerUserId="14255" LastActivityDate="2016-03-31T02:53:48.787" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26564" PostTypeId="2" ParentId="8950" CreationDate="2016-03-31T04:49:00.030" Score="1" Body="&lt;p&gt;With enough engines and all the right hardware...sure, it's possible.  See this report on tow launching an F-106: &lt;a href=&quot;http://www.nasa.gov/centers/dryden/history/pastprojects/Eclipse/index.html&quot; rel=&quot;nofollow&quot;&gt;http://www.nasa.gov/centers/dryden/history/pastprojects/Eclipse/index.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The problem is that it's just not practical.  Nevermind the actual execution of a pickup maneuver.   As mentioned in previous answers the costs of a standby fleet required to execute reliable pickups are very high.  There would be zero utilization of such a fleet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your edit asks about a fighter jet serving as the tow plane.  Yeah, sure, it's technically possible to build a trap of some kind to be a tow rig on an airliner.  If afterburner is required to keep both planes aloft tow time would be extremely limited though.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2016-03-31T04:49:00.030" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26565" PostTypeId="2" ParentId="26549" CreationDate="2016-03-31T06:36:37.013" Score="14" Body="&lt;p&gt;I always use the old saying;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;The North wind doth blow, and we shall have snow...&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since this saying originated in England and in England it is colder to the North, we can conclude that a North wind blows &lt;em&gt;from&lt;/em&gt; the North.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Incidentally, it is precisely the &lt;em&gt;opposite&lt;/em&gt; with ocean currents. The Gulf Stream is a North-Easterly current, because if you are floating in it, it will take you &lt;em&gt;to&lt;/em&gt; the North-East.&lt;/p&gt;&#xA;" OwnerUserId="9189" LastActivityDate="2016-03-31T06:36:37.013" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26567" PostTypeId="1" CreationDate="2016-03-31T07:01:41.250" Score="7" ViewCount="9106" Body="&lt;p&gt;Alice is approaching KTCY on &lt;a href=&quot;http://flightaware.com/resources/airport/TCY/IAP/RNAV+(GPS)+RWY+12/pdf&quot; rel=&quot;noreferrer&quot;&gt;RNAV (GPS) RWY 12 at KTCY&lt;/a&gt; circle NE to RWY 30. When she is turning right base to RWY 30 final, she loses visual contact with runway environment and decides to go missed. Spotted her GPS map, she notices she is right over the RWY 30 touchdown zone. How should she execute the missed approach?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a) Climb to 700 (600 to 700, HDG 300˚), Climb left turn (~left 260˚ over circling NA region), 3000 direct ECA hold.  &lt;/li&gt;&#xA;&lt;li&gt;b) Climb to 700 (600 to 700, HDG 300˚), Climb right turn (~right 100˚) 3000 direct ECA hold.&lt;/li&gt;&#xA;&lt;li&gt;c) Climb right turn (~right 100˚) 3000 direct ECA. Note Alice is above circling minimums 600 and initial climb to 700 is based on a HDG of 120˚.&lt;/li&gt;&#xA;&lt;li&gt;d) Continue fly over LNAV MAP, make a right 180˚, then climb 700, climb left turn 3000 direct ECA hold &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In more general senses, does circling nullify the initial climb, initial turn portion for a missed approach procedure, so that we may choose to intercept the following course, navigational radial, or direct to the fix from the side we turn with less degrees? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7jMhj.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7jMhj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-03-31T07:08:16.593" LastActivityDate="2018-12-26T15:04:41.583" Title="What are the guidelines to execute a missed approach during circling?" Tags="&lt;instrument-flight-rules&gt;&lt;circling-approach&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26569" PostTypeId="1" CreationDate="2016-03-31T07:43:16.157" Score="6" ViewCount="269" Body="&lt;p&gt;I was looking at the design diagram of actuators. &#xA;Every channel of the actuator is connected to a voltage differential transducer. The transducer outputs are fed to a sum voltage monitor. I could not understand its purpose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;How can summed voltage exist if there is a single sensor? Or am I missing something here?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YRx2g.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YRx2g.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="13197" LastEditDate="2016-04-20T15:12:44.420" LastActivityDate="2019-05-28T13:07:16.947" Title="What is the purpose of sum voltage monitor?" Tags="&lt;control-surfaces&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26571" PostTypeId="2" ParentId="26554" CreationDate="2016-03-31T10:28:15.287" Score="2" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is an ELT required on any type of aircraft carrying passengers over water?&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally, commercial transport aircraft are not required to carry an ELT.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;how are aircraft planned to be located after an accident over the ocean?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;I believe pilots are expected to use radio to inform controllers of any emergency.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If ATC are unable to contact an aircraft for an extended time, they instigate S&amp;amp;R based on the last known location of the aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The FDR and CVR are required to include an underwater location beacon (ULB), though this is only short range and has limited duration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;It is expected that, sometime in the future, commercial transport aircraft will be required to have automated systems that report their position frequently (perhaps every 15 minutes)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;References:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.iata.org/pressroom/pr/pages/2014-06-03-1.aspx&quot; rel=&quot;nofollow&quot;&gt;IATA - Aircraft Tracking Task Force (ATTF)&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.iata.org/pressroom/Documents/aircraft-tracking-task-force-faqs.pdf&quot; rel=&quot;nofollow&quot;&gt;ATTF FAQ&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.icao.int/safety/globaltracking/Documents/NATII%20Final%20Report.pdf&quot; rel=&quot;nofollow&quot;&gt;ICAO Normal Aircraft Tracking Implementation Initiative&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-03-31T10:39:00.690" LastActivityDate="2016-03-31T10:39:00.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26572" PostTypeId="1" CreationDate="2016-03-31T10:37:10.130" Score="6" ViewCount="223" Body="&lt;p&gt;Having currently read this article in Wikipedia, linked through Reddit, regarding &lt;a href=&quot;https://en.wikipedia.org/wiki/American_Airlines_Flight_191&quot;&gt;American Airlines Flight 191&lt;/a&gt;, which crashed due to maintenance issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Inside the article, it says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;McDonnell-Douglas, however, &quot;does not have the authority to either&#xA;  approve or disapprove the maintenance procedures of its customers.&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Is that the scenario in the current aviation industry, or has it changed. Why would airline companies not listen to the manufacturer and carry out non-approved procedures.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2016-04-02T13:10:47.717" Title="Do aircraft manufacturers have the authority to either approve or disapprove the maintenance procedures of its customers?" Tags="&lt;aircraft-maintenance&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="2" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="26573" PostTypeId="2" ParentId="26536" CreationDate="2016-03-31T12:55:37.277" Score="4" Body="&lt;p&gt;Since the first objective of any go-around is to establish a stable climb-out, the procedures involved all revolve around changing the current configuration to the required climb-out configuration. Stuff like power-up is pretty obvious in powered aircraft, and since most aircraft use far more flaps for landing configuration then take off, selecting take-off flaps also begins to seem more obvious. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The original question is based on an incomplete understanding about how flaps work, which some of the other answers here have not helped clarify. Most people know that flaps affect lift, drag and attitude, but tend to forget that each is affected by airspeed at different rates. In particular, drag increases far faster then lift when airspeed increases and this is why most aircraft use far more flaps for landing then for take-off. Also people tend to often forget that flaps are used during take-off to reduce the runway requirements, not to increase climb rate, and in a go-around, you are not on the runway so it is not a factor. &lt;/p&gt;&#xA;" OwnerUserId="2233" LastActivityDate="2016-03-31T12:55:37.277" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26574" PostTypeId="1" AcceptedAnswerId="26588" CreationDate="2016-03-31T13:24:01.337" Score="7" ViewCount="12500" Body="&lt;p&gt;What is the Keel Effect and how does it happen? Is it the same as Pendulum Effect or it doesn't exist? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Pilot's Handbook of Aeronautical Knowledege by the FAA has an explanation that says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An aircraft always has the tendency to turn the longitudonal axis of the aircraft into the relative wind. This &quot;weather vane&quot; tendency is similar to the keel of the ship and exerts a steadying influence on the aircraft laterally about the longitudonal axis. When an aircraft is disturbed and one wing dips, the fuselage weight acts as a pendulum returning the plane to its original attitude&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I know I'm like answering my own question, but is this explanation quite right? Because in &lt;a href=&quot;https://aviation.stackexchange.com/questions/26396/why-are-high-wing-aircraft-more-stable&quot;&gt;this question&lt;/a&gt; it is said that perhaps it doesn't exists or it means something different.&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-01T20:58:19.640" Title="What is the Keel Effect?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26575" PostTypeId="2" ParentId="25564" CreationDate="2016-03-31T13:50:24.313" Score="5" Body="&lt;p&gt;&lt;strong&gt;Short Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, it does not have a back-up, there are some fail-safe components in the system(see below), but in general the system itself is not duplicated. The system, together with a design that avoid ignition sources within the tanks, is just a part that contributes to prevent fuel tanks to ignite. An &lt;a href=&quot;https://en.wikipedia.org/wiki/Inerting_system&quot; rel=&quot;noreferrer&quot;&gt;Inerting System&lt;/a&gt; for commercial planes have been considered since &lt;a href=&quot;https://en.wikipedia.org/wiki/TWA_Flight_800&quot; rel=&quot;noreferrer&quot;&gt;1996 TWA accident&lt;/a&gt; and first regulation arrived in may 2006.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Longe Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The certification &lt;strong&gt;CS25.981 Fuel tank ignition prevention&lt;/strong&gt; states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No ignition source may be present at each point&#xA;  in the fuel tank or fuel tank system where&#xA;  catastrophic failure could occur due to ignition of&#xA;  fuel or vapors. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Design precautions must be taken to achieve&#xA;  conditions within the fuel tanks which reduce the&#xA;  likelihood of flammable vapors.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the function that should be achieved is &lt;em&gt;prevent tank ignition&lt;/em&gt; and there are two fronts two work on, &lt;em&gt;avoid ignition source&lt;/em&gt;, and &lt;em&gt;reduce fuel vapors&lt;/em&gt; (similar to the two slices of cheese that rbp was mentioning in the comments). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the fuel ignition system is a system designed to &lt;em&gt;avoid fuel vapors&lt;/em&gt;. As can be seen in the image below, within the systems there are some redundancies (e.g.: Dual Flow Shut Off Valve), but the system itself is not duplicated. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Moreover the system is not on the Minimum Equipment List (MEL), so the aircraft can still be dispatched with the system inoperative for 10 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XaGAk.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XaGAk.png&quot; alt=&quot;Schematic of the Fuel Tank Inerting System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="5568" LastEditDate="2016-03-31T17:57:42.353" LastActivityDate="2016-03-31T17:57:42.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26576" PostTypeId="2" ParentId="26522" CreationDate="2016-03-31T13:56:01.233" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is it possible to divert a plane to a distant airport?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I was on a flight that was diverted from Heathrow in the south of England to Prestwick in Scotland. It seemed like quite a long distance to me at the time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are actually plenty of airports closer to Heathrow than Prestwick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was due to major storms sweeping through the British Isles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane was initially diverted to Manchester but that airport was closed before we got there. Prestwick was pretty bad but I think the pilot was probably running out of choices within fuel range by that time.&lt;/p&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-03-31T14:01:27.413" LastActivityDate="2016-03-31T14:01:27.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26577" PostTypeId="2" ParentId="26572" CreationDate="2016-03-31T14:01:38.100" Score="3" Body="&lt;p&gt;For N-Registered Planes Under FAA regulations... (this may differ elsewhere in the world)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The short answer is No (although some &lt;a href=&quot;http://www.dommagazine.com/article/are-service-bulletins-mandatory-or-not&quot; rel=&quot;nofollow&quot;&gt;service bulletins may be legally required&lt;/a&gt;), the manufacturer can not legally enforce anything per say, however here's how it plays out. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most makers are at least in some capacity always testing their aircraft and aircraft procedures (at least the models in service). This may be as simple as inspecting the ones out there and looking at used parts for fatigue and what not. This in turn can lead to the company issuing a &lt;a href=&quot;https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1024688&quot; rel=&quot;nofollow&quot;&gt;Service Bulletin&lt;/a&gt; which is basically a document that says: &quot;hey here's something we found, you should look at it&quot;. This can apply to a any part of the aircraft as well as inspection and maintenance procedures. However service bulletins are not legally required to be complied with when issued by the company (although many may choose to comply). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand the Service Bulletins may trigger the FAA to issue an &lt;a href=&quot;https://www.faa.gov/regulations_policies/airworthiness_directives/&quot; rel=&quot;nofollow&quot;&gt;Airworthiness Directive&lt;/a&gt; which is a legally enforceable document. In this case the owner/operator of the aircraft is legally required to comply and alter their procedures.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case of the accident in question I think this is the &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/AOCADSearch/92392F3CC10BCD4486256E0C00739134?OpenDocument&quot; rel=&quot;nofollow&quot;&gt;AD that was issued as a result&lt;/a&gt;. You can find a full list of &lt;a href=&quot;https://www.faa.gov/regulations_policies/airworthiness_directives/search/?q=DC-10&amp;amp;makeModel=&amp;amp;type=Current&amp;amp;filter=&amp;amp;sort=effectiveDate&amp;amp;direction=desc&amp;amp;startRow=201&quot; rel=&quot;nofollow&quot;&gt;MD-10 AD's Here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On to the question of &lt;em&gt;why&lt;/em&gt; an airline may not listen. This is most likely a cost related issue. If the airlines insurance does not change and the cost to inspect or possibly replace a part that they don't legally need to replace is simply to high, they wont do so until its legally required. Again since every thing in aviation has two sides, manufactures may have the courtesy to replace the part at no cost to the owner. For example, when Porsche dropped the FAA Type Certification for the 3.2 motor in the Mooney M20PFM leaving all the owners somewhat high and dry, Mooney was kind enough to have the 40 odd aircraft updated with Continental motors (although many were destroyed in a hurricane while under going the change). The crux of it also comes down to the fact that only the government and its various organizations (here in US) can legally impose anything on an individual or company. So while it may be a good idea to heed the advice of the maker you may not be required to do so.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;--Edit--&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the comment below which is somewhat relevant to the original question. My understanding is that yes the FAR's may require you to refer to the manufacturer procedure but at the same time you only must refer to the procedures required (associated with the current certification of the airframe) for your airframe an SB with out an accompanying AD is a manufacturer procedure but is not legally required. So you may refer to it but you may not have to comply with it. Ill dig into the regulations and see if I can find the letter of the law on it.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-03-31T17:37:08.077" LastActivityDate="2016-03-31T17:37:08.077" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26578" PostTypeId="2" ParentId="23099" CreationDate="2016-03-31T14:03:46.850" Score="1" Body="&lt;p&gt;&lt;strong&gt;Preamble&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will keep it short and try to hit the point since I see some good answers here, please feel free to comment to get more detailed information&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does this process happen? &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In airport baggage is handled from the check-in desk to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Unit_load_device&quot; rel=&quot;nofollow&quot;&gt;Unit Load Device&lt;/a&gt;  (ULD) via a &lt;a href=&quot;https://en.wikipedia.org/wiki/Baggage_handling_system&quot; rel=&quot;nofollow&quot;&gt;Baggage Handling System&lt;/a&gt;. In about 15 minutes the baggage is automatically sorted, thanks to some sensors that scan the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bag_tag&quot; rel=&quot;nofollow&quot;&gt;bag tag&lt;/a&gt; attached to your luggage. In the meanwhile the baggage undergo X-Ray and potentially other security checks. It finally gets to the dedicated &quot;&lt;a href=&quot;https://en.wikipedia.org/wiki/Baggage_carousel&quot; rel=&quot;nofollow&quot;&gt;carousel&lt;/a&gt;&quot; (similar to the one where you retrieve your baggage). Here the operators put it in different ULD. Transit baggage are usually kept in a different ULD so that they are the first to be unloaded from the aircraft and can be quickly sorted, and re-directed to the correct connection flight. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How is passenger baggage transferred?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are three different technologies, and &lt;a href=&quot;https://www.beumergroup.com/en/products/airport-baggage-handling-systems&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; you can have a detailed look at them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Tilt trays where each baggage has its own tray and the tray is moved around.&lt;/li&gt;&#xA;&lt;li&gt;Convey belts, similar to the one you see in most airport&lt;/li&gt;&#xA;&lt;li&gt;Operators: the baggage are moved by hand by an operator and a &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_support_equipment#Dollies&quot; rel=&quot;nofollow&quot;&gt;dolly&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13754" LastEditorUserId="13754" LastEditDate="2016-04-01T07:55:59.540" LastActivityDate="2016-04-01T07:55:59.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26579" PostTypeId="2" ParentId="5065" CreationDate="2016-03-31T14:50:57.580" Score="1" Body="&lt;p&gt;Solar power on Earth peaks at somewhere between 400W and 1.3kW per square metre, in theory, at midday.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, we can typically expect more like 40-70% of this to be available due to inefficiencies in the solar panels and the fact the wing wouldn't be pointing directly at the sun. This is discounting clouds, and only at midday. At any other time, the amount available is lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking the best case scenario (1.3kW at midday at the equator, 70% available) then we still only have ~910 watts, or a little over 1.2 horsepower, per m^2&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's take a typical hang glider: a Wills Wing Alpha 210 has 19 square metres of wing area. That would give 17 kW, or 22.5 BHP. In theory, that's more than enough to get a microlight into the air, if you can keep the weight of the battery, motor, and solar panels down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, though, are you really going to be flying at the equator, with your wings perfectly level, at midday?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And more importantly, are you really going to get a 17kW motor, 20 m^2 of solar panels, wires, and a battery (pretty much required) into the weight of a hang glider that weighs, itself, less than a typical person?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's theoretically possible to make some kind of small ultralight type aircraft solar powered, but probably not until we find a way to make lighter motors and lighter solar panels that can take advantage of the wing area without causing weight/stability issues&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-03-31T14:50:57.580" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26580" PostTypeId="1" CreationDate="2016-03-31T15:24:45.570" Score="1" ViewCount="62" Body="&lt;p&gt;For instance an engine separated from aircraft (though most unlikely 1E-13 probability)  or wing got damaged, how is it reported to the pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Will it be reported as 'Engine Fail' or 'Left Wing Fail'? &#xA;If so, how is pilot supposed to know if it is a functional failure or a structural failure?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2016-03-31T15:24:45.570" Title="How are the structural failures reported to pilot" Tags="&lt;aircraft-design&gt;&lt;aircraft-structures&gt;" AnswerCount="0" CommentCount="9" ClosedDate="2016-03-31T16:35:16.137" ContentLicense="CC BY-SA 3.0" />
  <row Id="26581" PostTypeId="1" AcceptedAnswerId="26584" CreationDate="2016-03-31T15:42:39.010" Score="3" ViewCount="331" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Static_discharger&quot; rel=&quot;nofollow noreferrer&quot;&gt;Static dischargers&lt;/a&gt; have high electrical resistance, and work via corona discharge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if I understand correctly, what wicks do is limit the voltage that the aircraft builds up. But as the wick is ionizing the air around, I guess this voltage is rather high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do commercial, fixed-wing aircraft need any additional grounding method once on the ground, when the passengers are boarding/unboarding for example?. How it's done?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/19576/aircraft-hangar-storage-electrical-grounding-requirements&quot;&gt;This question&lt;/a&gt; is about grounding for hangar storage, and also explains grounding for refueling operations&lt;/p&gt;&#xA;" OwnerUserId="14018" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-03-31T20:23:24.340" Title="Are there additional electrical grounding methods besides static wicks?" Tags="&lt;safety&gt;&lt;static-electricity&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26583" PostTypeId="2" ParentId="26581" CreationDate="2016-03-31T16:22:46.863" Score="4" Body="&lt;p&gt;When fueling a grounded connection is established. Or at the very least the fuel tank is electrically bonded to the aircraft before the fuel line is connected by a clamp on a post on the landing gear.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="12220" LastEditDate="2016-03-31T17:00:03.060" LastActivityDate="2016-03-31T17:00:03.060" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26584" PostTypeId="2" ParentId="26581" CreationDate="2016-03-31T17:17:57.117" Score="5" Body="&lt;p&gt;Many aircraft tyres conduct electricity which also dissipates charges.  The compound contains &quot;carbon black&quot; or graphites.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the special case of helicopters using a hook to pick up a load from a hover, the wise ground handler will use a rod on the end of a grounded cable to earth the charge.  Helicopters can build up a &lt;strong&gt;lot&lt;/strong&gt; of static and many a ground handler has been left with smoking underpants by not heeding this advice.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-03-31T17:33:59.320" LastActivityDate="2016-03-31T17:33:59.320" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26585" PostTypeId="2" ParentId="26567" CreationDate="2016-03-31T19:03:10.637" Score="4" Body="&lt;p&gt;This is what ICAO specifies&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If visual reference is lost while circling to land from an instrument approach, the missed approach specified for that particular procedure shall be followed. The transition from the visual (circling) manoeuvre to the missed approach should be initiated by a climbing turn, within the circling area, towards the landing runway, to return to the circling altitude or higher, immediately followed by interception and execution of the missed approach procedure. The indicated airspeed during these manoeuvres shall not exceed the maximum indicated airspeed associated with visual manoeuvring. (ICAO Doc 8168: PANS-OPS, Volume 1, Chapter 7, Section 7.4)&#xA;  Related Articles&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-03-31T19:03:10.637" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26586" PostTypeId="1" AcceptedAnswerId="26598" CreationDate="2016-03-31T20:06:09.893" Score="6" ViewCount="269" Body="&lt;p&gt;&lt;strong&gt;tl;dr&lt;/strong&gt;: How do I go from non-airman to commercial UAS pilot under an FAA 333 exemption?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the rules are imminently changing, but waiting for the formal implementation of the &lt;a href=&quot;https://www.faa.gov/uas/nprm/&quot;&gt;NPRM&lt;/a&gt; could mean a very long wait before even getting started, and there is already a &lt;a href=&quot;https://www.faa.gov/uas/legislative_programs/section_333/&quot;&gt;backlog of section 333 petitions&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Say I have a small (under 55 pounds) quadrotor aircraft, and I want to fly it for &quot;&lt;a href=&quot;https://www.faa.gov/uas/civil_operations/&quot;&gt;civil operations&lt;/a&gt;&quot; (commercial). As a non-airman, what do I need to do before I can operate the craft in this manner?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As near as I can determine, the process is something like this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Obtain a pilot license&lt;/li&gt;&#xA;&lt;li&gt;File a petition for part 333 exemption&lt;/li&gt;&#xA;&lt;li&gt;Acquire either a SAC or Waiver/CoA&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Do I really need to obtain a pilot license of some sort for real aircraft (either PPL, sport, or recreational) for this purpose, or can I legally operate the craft using some other short-cut? Is there a difference if I plan to fly a craft with a SAC rather than a craft which has none?&lt;/p&gt;&#xA;" OwnerUserId="8233" LastActivityDate="2016-04-01T12:48:39.560" Title="How do I get certified to fly under FAA 333?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;unmanned-aerial-vehicle&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26588" PostTypeId="2" ParentId="26574" CreationDate="2016-03-31T22:31:20.433" Score="7" Body="&lt;p&gt;According to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Keel_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;keel effect page&lt;/a&gt; on Wikipedia it is the rolling moment created by the fuselage and vertical surfaces in a sideslip if the center of pressure is vertically offset from the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Functions of a keel&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The keel of a ship (besides shifting the center of gravity below the &lt;a href=&quot;https://en.wikipedia.org/wiki/Metacentric_height&quot; rel=&quot;nofollow noreferrer&quot;&gt;metacenter&lt;/a&gt;) provides a stabilizing side force when the ship rolls. The same is achieved by a tail surface, but in aviation this is called &lt;a href=&quot;https://aviation.stackexchange.com/questions/7734/how-can-i-calculate-the-rolling-moment-of-an-aileron-for-a-given-plane-based-on/7737#7737&quot;&gt;roll damping&lt;/a&gt;. The much larger wing tends to dominate roll damping, so the effect of the vertical surface is small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next task of the keel is to balance the side force and rolling moment from the sails in crosswind conditions. It does this by letting the boat build up a sideslip condition until the side force from the keel and hull balances the side force from the sails, and the rolling moment from the side force and from &lt;a href=&quot;https://en.wikipedia.org/wiki/Sailing#Heeling&quot; rel=&quot;nofollow noreferrer&quot;&gt;heeling&lt;/a&gt; balances the rolling moment from the sails. The keel effect is this rolling moment due to a sideslip condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few aircraft with very small wings and large vertical surfaces do indeed suffer from excessive moments created by side loads on those vertical surfaces. The best known of those is probably the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed F-104 Starfighter&lt;/a&gt;. The massive tail on the upswept rear fuselage made 10° anhedral necessary to get the sideslip-induced rolling moment right.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Pendulum effect&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia page also mentions the pendulum effect and calls both the fuselage contribution to the dihedral effect. Man, if there is ever a competition for the most misleading name of an effect, this would be the winning entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Pendulum&quot; rel=&quot;nofollow noreferrer&quot;&gt;pendulum&lt;/a&gt; is a mass mounted &lt;strong&gt;below&lt;/strong&gt; the &lt;a href=&quot;https://en.wiktionary.org/wiki/pivot&quot; rel=&quot;nofollow noreferrer&quot;&gt;pivot&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Metacentric_height&quot; rel=&quot;nofollow noreferrer&quot;&gt;metacenter&lt;/a&gt;, so it will stabilize in the down position. It seems the adherents of the pendulum effect belief believe that the plane is somehow hinged at the center of the wing. &lt;strong&gt;This is so wrong!&lt;/strong&gt; A flying aircraft &lt;strong&gt;is not hinged&lt;/strong&gt;, so all motion is around the center of gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is different with airships: As @JanHudec points out in the comments, the buoyancy of the lifting gas always works against gravity whereas the lift of a wing acts perpendicular to its span and the airspeed. This does produce a moment when the airship rolls, and the heavy gondola is pulled down by the same effect which pulls down a pendulum. Also, due to an airship's low density (by definition very close to the density of the air it displaces) the aerodynamic side forces on an airship are much larger compared to the inertial forces. This lets the airship effectively pivot around a point near the center of the envelope. Note that airships have no means of roll control - it is just gravity which ensures that the gondola stays on the lower side of the hull.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you can argue that the same is true for aircraft, only with much smaller aerodynamic forces. Yes, but those side forces are vanishingly small in comparison to the wing's aerodynamic forces which, again by definition, are close to the weight of the aircraft. A small change there will completely dominate the picture, and the small loads on the fuselage are just a rounding error. By moving the control surfaces, the pilot can shift the lift vector around almost as he/she likes, and the forces on the fuselage are insignificant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that &lt;a href=&quot;https://aviation.stackexchange.com/questions/12383/can-you-fly-an-airplane-at-a-90-roll-angle-without-losing-altitude/12386?s=1%7C0.2181#12386&quot;&gt;knife edge flight&lt;/a&gt;, a situation when the side force on the fuselage really is close to the aircraft's weight, needs lots of fuselage area and a powerful engine. Fuselage loads in normal flight are a fraction of those in knife edge flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-04-01T20:58:19.640" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26589" PostTypeId="1" CreationDate="2016-03-31T22:56:04.237" Score="7" ViewCount="945" Body="&lt;p&gt;I came across an extremely interesting note from a &lt;a href=&quot;https://en.wikipedia.org/wiki/G-LOC&quot; rel=&quot;nofollow&quot;&gt;wiki article on G-LOC&lt;/a&gt; (g-force loss of consciousness, or blackout):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Brief but vivid dreams have been reported to follow G-LOC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Sadly no citation. Where can I read more about this? I did a quick Google search on &quot;pilots dream g-force blackout&quot; but only got 2 relevant hits that didn't tell me much. Some reddit posts described a dream trapped in a maze and a trip to Hawaii, that's about it. They sometimes described it as an out-of-body experience instead of a dream.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anyone know where to go to read more? Is this really a common phenomenon?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2017-09-26T13:24:51.723" LastActivityDate="2017-09-26T13:24:51.723" Title="Where can I learn more about pilots' dreams during G-LOC?" Tags="&lt;military&gt;&lt;pilots&gt;&lt;medical&gt;&lt;fighter&gt;&lt;g-forces&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-04-01T18:01:49.147" ContentLicense="CC BY-SA 3.0" />
  <row Id="26590" PostTypeId="2" ParentId="26547" CreationDate="2016-03-31T23:35:47.240" Score="2" Body="&lt;p&gt;The term &#xA;$$V_q\cdot{sin}\theta_t$$&#xA;is a speed, not a force, so it cannot be an accurate expression of the thrust vector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Propellers &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power/8822#8822&quot;&gt;accelerate the air flowing through the propeller disc&lt;/a&gt; in the direction of the propeller axis (or perpendicular to the propeller disc), so the force is only parallel to the propeller axis when the airspeed is aligned with the propeller axis. If the airspeed is at an angle to the propeller axis, the thrust vector is tilted towards the airspeed vector. The magnitude of this tilt depends on the speed increase of the propeller stream relative to airspeed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-03-31T23:35:47.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26591" PostTypeId="1" CreationDate="2016-04-01T01:29:36.033" Score="6" ViewCount="536" Body="&lt;p&gt;A long time ago, I had the privilege of flying in 4 engine turboprop airplanes in which the props were 'synched'(blades rotating in same speed) which of course is necessary for smooth thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, one of the exercises we performed(as a military aircraft) was called a &quot;crash and dash&quot;; we dove as steep as we could until we could get as close as we could to the surface, then pull out of the dive and attempt to 'fly below' any surface radar that may be tracking us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every time we did this maneuver it threw the props out of 'synch' and cause the airframe to shudder violently. Anything that was literally not 'nailed down' was thrown through the cockpit or cabin.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, what effect does this have on the airframe and does one of the events require an inspection, or shorten the check cycle?&lt;/p&gt;&#xA;" OwnerUserId="3671" LastEditorUserId="13197" LastEditDate="2016-04-20T15:12:21.307" LastActivityDate="2016-04-20T19:00:35.450" Title="What is the Effect of Unsynchronized Propellers?" Tags="&lt;propeller&gt;&lt;airframe&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26593" PostTypeId="2" ParentId="26589" CreationDate="2016-04-01T05:09:25.867" Score="7" Body="&lt;p&gt;I'm not sure if you've come across this or not, but the paper &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a200214.pdf&quot; rel=&quot;noreferrer&quot;&gt;Recovery from &#xA;Gz-lnduced Loss of Consciousness:Psychophysiologic Considerations&lt;/a&gt; has some details on this phenomenon. It describes the tests carried out on eight volunteers.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;This does not appear to be very common- five 'dreams' were recalled out of 21 acceleration runs. The subjects seem to have indicated that these were definitely 'dreams' as opposed to 'thoughts'. Also, the report notes:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... it is difficult objectively to determine exactly what the subjects experienced during their individual G-LOC episodes (dream or thought) or even state that G-LOC can be equated to a normal sleep mental state (in relation to dream activity)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another paper &lt;a href=&quot;https://dokumente.unibw.de/pub/bscw.cgi/d5424523/ASEM_2000_71%285%29_496-500.pdf&quot; rel=&quot;noreferrer&quot;&gt;Further Support for the  Concept of a  G-LOC Syndrome: A Survey of Military High-Performance Aviators&lt;/a&gt; shows that the dream-like state occurs in about 15% of the cases. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 'dream' state appears to be restricted to &amp;lt;13s and vary from person to person (in some cases, they were not aware that they've lost conciousness).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-01T05:09:25.867" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26594" PostTypeId="1" AcceptedAnswerId="26624" CreationDate="2016-04-01T08:02:11.267" Score="12" ViewCount="1426" Body="&lt;p&gt;Disregarding financial and difficulty concerns, would it be possible (legal) for someone to obtain a PPL license on a jet aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is possible, would there be any restrictions on the license on operating piston engine aircrafts?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;EDIT: the linked question asks about EASA regulations. This question is about FAA regulations, thus, the answer in the linked question does not apply.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-04-02T14:16:25.163" LastActivityDate="2016-04-02T19:34:38.337" Title="Is it legal to begin pilot training on a jet?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;" AnswerCount="2" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26595" PostTypeId="1" CreationDate="2016-04-01T11:41:15.213" Score="1" ViewCount="387" Body="&lt;p&gt;How can I estimate the maximum required take-off power for a propeller aircraft with the following available data?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Wing surface S&lt;/li&gt;&#xA;&lt;li&gt;Max. lift coefficient in T/O configuration cL&lt;/li&gt;&#xA;&lt;li&gt;Take-off distance available d (regardless of obstacle clearance etc.)&lt;/li&gt;&#xA;&lt;li&gt;MTOW&lt;/li&gt;&#xA;&lt;li&gt;Airfield altitude (let us assume MSL)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Is the data available even enough?&lt;/p&gt;&#xA;" OwnerUserId="6859" LastEditorUserId="1696" LastEditDate="2018-04-13T20:04:30.930" LastActivityDate="2018-04-13T20:04:30.930" Title="How can I estimate the required T/O power for propeller aircraft?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26596" PostTypeId="1" AcceptedAnswerId="26682" CreationDate="2016-04-01T11:52:49.573" Score="18" ViewCount="1411" Body="&lt;p&gt;There are several Zero-G airplanes to experiment briefly microgravity without going into orbit. One is the A310 from Novespace (F-WNOV):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yjWNf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yjWNf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Novespace A310 F-WNOV (source: Jonas Wirz at &lt;a href=&quot;http://www.airplane-pictures.net/photo/614790/f-wnov-noverspace-zero-g-airbus-a310/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane-Pictures.net&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When a Zero-G flight is executed, fuel should take the form of a sphere in the tanks, like demonstrated in the cabin for a beverage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xEout.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xEout.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Advertisement in microgravity (&lt;a href=&quot;https://www.youtube.com/watch?v=uweiXnxKY-M&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thoughts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;This effect won't appear in negative G, subject to the design, fuel lines may still be immersed in tanks, this cannot be the case in micro-gravity. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The 0G segment is likely flown with power. First this is not a continuously descending flight as seen below. Second, friction will slow down the free fall anyway and must be compensated by some acceleration from the engines.&#xA;&lt;BR&gt;&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nNPGz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nNPGz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;0G segment is not limited to the descent (based on &lt;a href=&quot;https://en.wikipedia.org/wiki/Reduced-gravity_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How does Airbus ensure the fuel is still delivered to the engines at the required pressure, without air?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Related: &lt;a href=&quot;https://aviation.stackexchange.com/questions/19047/are-engines-fed-differently-in-reduced-gravity-aircraft&quot;&gt;Are engines fed differently in reduced gravity aircraft?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically it says no modification is required because the lines are pressurized, and this is supported by a 1966 Nasa study (&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660014262.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Use of aircraft for zero-gravity environment&lt;/a&gt;) which is not more detailed. The line being pressurized downstream of the pumps seems only one element of an adequate design. Upstream fuel will experiment the effect of micro-gravity and lines are no more immersed in the fuel. Air can enter and create a problem when reaching a pump or an engine. Pumps could be drained. Maybe the problem won't appear during the 0G segment, but it should appear later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to have the details about how pumps, pressure, flow, or anything else contribute to maintain a good fuel supply to the engines.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;This is the fuel system for the A310:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2EzlN.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2EzlN.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.smartcockpit.com/download.php?path=docs/&amp;amp;file=A310-Fuel_System.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="22726" LastEditDate="2019-01-01T01:33:06.033" LastActivityDate="2019-01-01T01:33:06.033" Title="How is fuel managed in the Zero-G A310?" Tags="&lt;fuel-systems&gt;&lt;airbus-a310&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="26597" PostTypeId="2" ParentId="26595" CreationDate="2016-04-01T11:56:02.400" Score="2" Body="&lt;p&gt;You need takeoff speed (from the lift coefficient, wing surface and altitude) and the time in which you need to achieve it (before you run off the runway). That'll give you the needed acceleration ($a = \frac{\Delta v}{s}$) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From that you can know how much force the prop must generate ($F = ma$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add some margin to account for friction losses.&lt;/p&gt;&#xA;" OwnerUserId="609" LastActivityDate="2016-04-01T11:56:02.400" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26598" PostTypeId="2" ParentId="26586" CreationDate="2016-04-01T12:48:39.560" Score="3" Body="&lt;p&gt;The FAA's &lt;a href=&quot;https://www.faa.gov/uas/faq/#qn19&quot; rel=&quot;nofollow&quot;&gt;FAQ says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Is an FAA-issued pilot certificate required to operate a civil UAS under an experimental airworthiness certificate or a grant of&#xA;  exemption under Section 333?&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If the aircraft is issued an&#xA;  airworthiness certificate, a pilot certificate is required.&lt;SUP&gt;5&lt;/SUP&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Pilot&#xA;  certification requirements for petitions for exemption under Section&#xA;  333 are evaluated on a case-by-case basis.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The footnote links to this &lt;a href=&quot;http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgOrders.nsf/0/10947cee0052205886257bbe0057bd76/$FILE/8130.34C.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA order&lt;/a&gt; called &lt;em&gt;Airworthiness Certification of Unmanned Aircraft Systems and Optionally Piloted Aircraft&lt;/em&gt;, which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;b. UA PIC Certification and Ratings Requirements.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The PIC must hold and be in possession of, at a minimum, an FAA private pilot&#xA;  certificate, with either an airplane, rotorcraft, or powered-lift&#xA;  category; with single- or multiengine class ratings, appropriate to&#xA;  the type of UA being operated.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The PIC must have and be in&#xA;  possession of a valid second-class (or higher) airman medical&#xA;  certificate issued under 14 CFR part 67, Medical Standards and&#xA;  Certification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, it looks like there are two possibilities:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Your UAS has an airworthiness certificate, therefore you need a pilot's license per the Order (private at least, not sport or recreational)&lt;/li&gt;&#xA;&lt;li&gt;Your UAS doesn't have an airworthiness certificate, therefore your section 333 petition will be evaluated individually and the FAA will tell you if you need a license or not&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-04-01T12:48:39.560" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26599" PostTypeId="2" ParentId="26517" CreationDate="2016-04-01T15:50:05.263" Score="13" Body="&lt;p&gt;The HondaJet is &lt;a href=&quot;https://www.hondajet.com/news/article?articleType=pressrelease&amp;amp;categoryType=d82b11b7-98a3-4a02-9688-5bd05eef476d#0&quot;&gt;type certified by the FAA&lt;/a&gt;. The &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/4d17265c4e1d151886257f37005117a4/$FILE/A00018AT_Rev0.pdf&quot;&gt;type certificate&lt;/a&gt; says that it's certified in the normal category under &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr23_main_02.tpl&quot;&gt;14 CFR 23&lt;/a&gt;, which includes the requirements to be able to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a511d47517bda1b24da9aa93bf5d9ba0&amp;amp;mc=true&amp;amp;node=se14.1.23_166&amp;amp;rgn=div8&quot;&gt;take off&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a511d47517bda1b24da9aa93bf5d9ba0&amp;amp;mc=true&amp;amp;node=se14.1.23_167&amp;amp;rgn=div8&quot;&gt;climb&lt;/a&gt; on a single engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Simply put, the HondaJet has plenty of surplus thrust even on one engine and there should be no problem at all landing it after a single engine failure, assuming no other complications.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-04-01T15:50:05.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26600" PostTypeId="2" ParentId="26567" CreationDate="2016-04-01T15:56:38.077" Score="5" Body="&lt;p&gt;Flying a missed approach while circling can require some judgement, as the procedures are designed to originate at the missed approach point. Going missed while circling can mean starting the procedure some distance away from the MAP. The goal of the initial procedure should be to intercept the published missed approach &lt;em&gt;course&lt;/em&gt;, while maintaining obstacle and traffic clearance. Put another way, a pilot may deviate from the letter of the procedure, if doing so follows the spirit of it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this situation, I would recommend option B. The procedure will provide obstacle clearance when started from three points: 443 MSL and about 4000 feet from the RW12 threshold (LPV minima); 638 MSL and about 11,500 feet from RW12 (LNAV/VNAV); and 600 MSL over the RW12 threshold (LNAV and circling). The procedure assumes you can climb at least 200 ft/nm, so to climb 100 feet would require less than 3035 feet across the ground. This puts you within the area where the published missed approach starts. Once you reach 700 feet, you can turn directly to the VOR and continue the procedure as published. The initial turn would normally be towards the landing runway, but in this example the runway is straight ahead.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you descended below circling minima and needed a significant climb to get back, consider circling over the airport until either reaching 700 feet before flying towards the VOR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA has recommends the thought process above in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM&lt;/a&gt;, section 5-4-21. Emphasis mine:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-4-21 (c):&lt;/strong&gt; If visual reference is lost while circling−to−land&#xA;  from an instrument approach, the missed approach&#xA;  specified for that particular procedure must be&#xA;  followed (unless an alternate missed approach&#xA;  procedure is specified by ATC). &lt;strong&gt;To become&#xA;  established on the prescribed missed approach&#xA;  course, the pilot should make an initial climbing turn&#xA;  toward the landing runway and continue the turn until&#xA;  established on the missed approach course.&lt;/strong&gt; Inasmuch&#xA;  as the circling maneuver may be accomplished in&#xA;  more than one direction, &lt;strong&gt;different patterns will be&#xA;  required to become established on the prescribed&#xA;  missed approach course&lt;/strong&gt;, depending on the aircraft&#xA;  position at the time visual reference is lost.&#xA;  Adherence to the procedure will help assure that an&#xA;  aircraft will remain laterally within the circling and&#xA;  missed approach obstruction clearance areas. Refer&#xA;  to paragraph h concerning vertical obstruction&#xA;  clearance when starting a missed approach at other&#xA;  than the MAP.  &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5-4-21 (h):&lt;/strong&gt; ... In the event a balked (rejected) landing occurs at a position&#xA;  other than the published missed approach&#xA;  point, the pilot should contact ATC as soon as possible&#xA;  to obtain an amended clearance. &lt;strong&gt;If unable to&#xA;  contact ATC for any reason, the pilot should attempt&#xA;  to re−intercept a published segment of the missed approach&#xA;  and comply with route and altitude&#xA;  instructions.&lt;/strong&gt; If unable to contact ATC, and in the pilot’s&#xA;  judgment it is no longer appropriate to fly the&#xA;  published missed approach procedure, then consider&#xA;  either maintaining visual conditions if practicable&#xA;  and reattempt a landing, or a circle−climb over the&#xA;  airport...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AIM includes a diagram that demonstrates a pilot turning against the missed-approach instructions when that is the safer course. The missed approach requires a climbing right turn to the VOR; the pilot in the scenario on the right chooses to make a left turn as that allows the initial climb to take place over the airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6MBre.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6MBre.png&quot; alt=&quot;AIM Fig 5-4-30 and 5-4-31&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: FAA AIM&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="136" LastActivityDate="2016-04-01T15:56:38.077" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26601" PostTypeId="1" CreationDate="2016-04-01T17:22:34.047" Score="1" ViewCount="489" Body="&lt;p&gt;Some aircraft have engine beneath the wings and some have at the rear of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the factors that are considered while deciding where to mount an engine? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is one configuration advantageous over other?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="1467" LastEditDate="2016-04-01T17:32:12.193" LastActivityDate="2016-04-01T18:09:53.633" Title="What factors lead to mounting engines towards the rear of aircraft" Tags="&lt;aircraft-design&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ClosedDate="2016-04-01T18:01:25.363" ContentLicense="CC BY-SA 3.0" />
  <row Id="26602" PostTypeId="2" ParentId="26601" CreationDate="2016-04-01T17:51:39.743" Score="3" Body="&lt;p&gt;I am just a Flight Sim enthusiast so everything I say should be heavily scrutinized, but there is a flightsim that features the A-10C which has an engine configuration just like you describe as you can see in the picture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QNxPT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QNxPT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.digitalcombatsimulator.com/en/downloads/documentation/dcs_a-10c_flight_manual_en/&quot; rel=&quot;nofollow noreferrer&quot;&gt;(ingame) flight manual&lt;/a&gt; has the following to say about the engine configuration:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Engines&lt;/strong&gt; &#xA;  All versions of the A-10 have been powered by twin TF-34-GE-100A engines that are mounted high&#xA;  on the rear fuselage between the wings and the rear stabilizers. The unusual placement of the&#xA;  engines provides several distinct advantages:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The high mounting reduces the likelihood of the engines ingesting Foreign Object Debris&#xA;  (FOD) when operating from rough, forward bases in war-time.&lt;/li&gt;&#xA;  &lt;li&gt;Engines can remain running when aircraft is being rearmed and refueled. This leads to&#xA;  faster mission turn-around&lt;/li&gt;&#xA;  &lt;li&gt;Ease of servicing the engines&lt;/li&gt;&#xA;  &lt;li&gt;Reduced IR signature from below due to the shielding of the horizontal stabilizer.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Another related thing I found was how they combine with the leading edge slats, it says.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Added leading edge slats for improved airflow to engines at higher angles of attack&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As most of these reasons are in a military setting I cannot comment on the advantages for civilian aviation.&lt;/p&gt;&#xA;" OwnerUserId="13699" LastEditorUserId="13699" LastEditDate="2016-04-01T18:09:53.633" LastActivityDate="2016-04-01T18:09:53.633" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26603" PostTypeId="2" ParentId="21265" CreationDate="2016-04-01T20:26:41.367" Score="4" Body="&lt;p&gt;The casing treatments shown work by providing an alternative path for the rotor tip leakage flows; which otherwise collect at the rotor tip when highly loaded and block the flow resulting in a surge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lack of change is because there was no significant improvement in computing power between the 50s and the 70s that would help with such designs, (in fact it is only very recently that the flows can be accurately modelled.) and the cost of the experiments required to substantially iterate the design would be prohibitive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference in designs is partially driven by parallel development, partially by patent avoidance, and partially the desire to minimise the impact on the compressor's components and its efficiency.&lt;/p&gt;&#xA;" OwnerUserId="14278" LastActivityDate="2016-04-01T20:26:41.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26604" PostTypeId="1" AcceptedAnswerId="26605" CreationDate="2016-04-01T21:52:42.130" Score="15" ViewCount="1682" Body="&lt;p&gt;I haven't seen these markings in other airports in the world. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/howzt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/howzt.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They also appear in other Japanese airports. What do they mean?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2018-07-08T19:10:58.437" LastActivityDate="2018-07-08T19:17:04.897" Title="What are these markings on the runway at Haneda Airport?" Tags="&lt;airport-markings&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26605" PostTypeId="2" ParentId="26604" CreationDate="2016-04-01T22:19:32.163" Score="19" Body="&lt;p&gt;I dug around for a while but couldn't find any official documentation on this (I suspect someone whose Japanese is better than mine will have to do that.)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But!  I did find the markings on all of the Haneda Airport runways and I noticed they were roughly halfway along the length of the entire physical runway.  A little bit of measuring confirmed my suspicion, it appears the marks show you exactly where the halfway point is on that particular runway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also looked at other Japanese airports and took measurements of the same markings at Narita, Osaka and Kobe.  All airports turned up the same results.  (You can use the measure tool on Google Maps to confirm if you'd like to)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also find out that not all airports in Japan have these markings.  Neither Nagasaki nor Osaka seem to have markings like the ones mentioned above...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure why they mark the halfway point...someone with better Japanese than me will have to look into the history of that decision.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;  &lt;a href=&quot;https://aviation.stackexchange.com/users/3201/mins&quot;&gt;mins&lt;/a&gt; found some documentation and posted it in the comments (thanks mins!):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.mlit.go.jp/jtsb/eng-air_report/JA3919.pdf&quot; rel=&quot;noreferrer&quot;&gt;This&lt;/a&gt; is an English translation of a report done by the Japan Transport Safety Board regarding a runway overrun.  They mention the meaning of the markings (in passing) on page 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a capture mins created of the relevant part of the report:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DHZBZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DHZBZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, there we go, more than just circumstantial evidence we have the aviation authority of Japan saying it's true.  It's the halfway mark for the runway.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="13197" LastEditDate="2018-07-08T19:17:04.897" LastActivityDate="2018-07-08T19:17:04.897" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="26606" PostTypeId="1" AcceptedAnswerId="26607" CreationDate="2016-04-01T22:24:44.517" Score="41" ViewCount="7576" Body="&lt;p&gt;There is one spoiler that isn't totally deployed. Look:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JxQtW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JxQtW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Singapore-Airlines/Boeing-777-212-ER/2330739/L/&amp;amp;sid=82542e69fd8be766c9bf13d48543173c&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And also on this other picture:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eNRYT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eNRYT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Swiss-International-Air/Boeing-777-3DE/ER/2801695/L/&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why aren't they deployed at the same angle?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="12220" LastEditDate="2016-04-01T23:45:18.150" LastActivityDate="2019-08-16T14:46:48.017" Title="Why does one of the Boeing 777's spoilers deploy differently from the rest?" Tags="&lt;wing&gt;&lt;boeing-777&gt;&lt;spoilers&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26607" PostTypeId="2" ParentId="26606" CreationDate="2016-04-01T22:57:38.470" Score="57" Body="&lt;p&gt;Roll control is provided by 2 flaperons, 2 ailerons, and 14 spoilers.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoiler panels 4 and 11 are controlled mechanically rather than electrically. They are driven directly from control wheel deflections via a control cable. In case of compete electrical loss, limited roll control is available until the electrical system is restored.  This probably explains the difference in rigging. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Spoiler panels 4 and 11 are also used as speedbrakes, both in the air and on the ground. The speedbrake function for this spoiler pair only has two positions: stowed and fully extended. The speedbrake commands for spoilers 4 and 11 are electrical in nature, with an ACE (actuator control electronics) giving an extend or retract command to a solenoid operated valve in each of the actuators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once that spoiler pair has been deployed by a speedbrake command, there is no control wheel speedbrake command mixing, as there is on all the other fly-by-wire spoiler surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.davi.ws/avionics/TheAvionicsHandbook_Cap_11.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boeing B-777: Fly-ByWire&#xA;Flight Controls&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tlA3Z.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tlA3Z.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z8pVz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z8pVz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-01T23:16:50.873" LastActivityDate="2016-04-01T23:16:50.873" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26608" PostTypeId="1" AcceptedAnswerId="26609" CreationDate="2016-04-02T00:04:55.560" Score="1" ViewCount="1024" Body="&lt;p&gt;When flying at cruise altitude, the pressure inside the aircraft is higher than outside and that means a lot of air is pushing the door outwards. So how does the door stay in place and not open?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm not asking if a passenger could open a door, because that's almost impossible. I'm asking how does the door not open if there is a lot of air pushing it outwards?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="62" LastEditDate="2016-04-02T03:38:26.857" LastActivityDate="2016-04-02T03:38:26.857" Title="Why doesn't the pressure inside an airliner push the doors open?" Tags="&lt;airliner&gt;&lt;doors&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-04-02T06:31:39.070" ContentLicense="CC BY-SA 3.0" />
  <row Id="26609" PostTypeId="2" ParentId="26608" CreationDate="2016-04-02T00:24:44.683" Score="7" Body="&lt;p&gt;Most of the airline doors are &lt;a href=&quot;https://en.wikipedia.org/wiki/Plug_door&quot; rel=&quot;nofollow noreferrer&quot;&gt;plug type&lt;/a&gt;- i.e. they are wedge shaped, so that the pressure differential pushes it against the fuselage and prevents opening. For example, the following image shows the Boeing 737 door.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2jiPo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2jiPo.jpg&quot; alt=&quot;B737 door&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airteamimages.com/boeing-737_HL8248_korean-air_155564.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;airteamimages.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the door is bigger on the inside, so that when it is locked in position, the pressure will push it against the fusealge, preventing it from opening. For opening the door, it has to be swung inwards before moving out.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-02T00:24:44.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26610" PostTypeId="1" CreationDate="2016-04-02T05:16:54.220" Score="1" ViewCount="510" Body="&lt;p&gt;For cars, I've heard of LLumar used as window tint.&lt;br&gt;&#xA;Do jet aircraft use window tint? If so, what type of window tint do they use?&lt;/p&gt;&#xA;" OwnerUserId="14281" LastEditorUserId="65" LastEditDate="2016-04-03T03:45:24.060" LastActivityDate="2016-04-03T04:16:32.420" Title="Do jets use tinted windows?" Tags="&lt;aircraft-design&gt;&lt;windows&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26611" PostTypeId="1" CreationDate="2016-04-02T08:01:29.610" Score="9" ViewCount="1224" Body="&lt;p&gt;As I read &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.169&quot;&gt;14 CFR 91.169&lt;/a&gt; literally, I understand an alternate airport listing waiver can be granted if the destination airport&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Has at least one instrument approach procedure from an authorized source.&lt;/li&gt;&#xA;&lt;li&gt;reports/predicts within ETA ± 1 hours, ceiling 2000 or higher, 3 SM or greater (1-2-3 Rule) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Q1) So one case, If we plan an IFR flight to an airport without any IAP, even if the whole area is SKC, we are legally required include an alternate airport?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the alternate airport qualifications, I get the following following flow,&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there any weather reporting or forecast service at this airport?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, Go to Step 2&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, return Unqualified Alternate. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the weather good enough for basic VFR descend from MEA, approach and landing at ETA? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, return Qualified Alternate&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, Go to Step 3.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Does the airport have an IAP?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, Go to Step 4&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, return Unqualified Alternate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is your airplane WAAS-equipped?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, include GPS approaches in your candidate IAP pool. Go to Step 5&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, remove all GPS approaches from your candidate IAP pool. Go to Step 5.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Remove any IAP with unmonitored or inoperative equipments from your candidate IAP pool. Go to Step 6.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Find the alternate minimums for each IAP in your candidate IAP pool from Step 5, or if no alternate minimum is published apply 600-2 for precision approach and 800-2 for non-precision approach. Go to Step 7.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Compare the your lowest minimums from Step 6 with the weather report or forecast at alternate airport. Is your lowest minimums greater than the weather minima?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, return Qualified Alternate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No, return Unqualified Alternate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Q2) Does this flow reflect the current FAA alternate airport requirements? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Q3) In an actual approach to the alternate, can we first attempt an approach that is different from the one we used to satisfy the alternate weather minimum planning requirement? (the one selected from Step 7 for lowest minimums). Technically, The IAP to use is not a required part of a flight plan.&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="69" LastEditDate="2018-03-30T20:07:53.903" LastActivityDate="2018-03-30T20:07:53.903" Title="What are the US flight planning regulations for an alternate airport?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;instrument-flight-rules&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26614" PostTypeId="1" AcceptedAnswerId="26615" CreationDate="2016-04-02T10:47:19.747" Score="12" ViewCount="1956" Body="&lt;p&gt;FMS/FMGS computers can fly many modern aircraft between waypoints set by the crew. They find their way using aids like IRS, GPS, DME, and ILS and are able to manage route, altitude and thrust.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VruRe.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VruRe.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Mode control panel (MCP) on a B737 NG (probable source: &lt;a href=&quot;https://www.flickr.com/photos/109969275@N07/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Alessio Meneghetti on Flickr&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Most of a commercial flight can be handled by computers when everything goes as planned, air regulations don't seem to forbid such automation.&lt;/p&gt;&#xA;&lt;p&gt;On the other hand the crew ensures flight safety, programs, engages and monitors computers, handles changes, hitches and abnormal situations, takes decisions and re-programs computers with new instructions. Some configuration changes (e.g. landing gears) are also beyond computer reach.&lt;/p&gt;&#xA;&lt;p&gt;I'm curious to know which actions are manual and how much time is spent for them from entering the takeoff runway to leaving the landing runway, e.g. for a 2,500 NM commercial flight? What is the current trend for airlines policies regarding the use of these automation capabilities?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="33692" LastEditDate="2021-03-24T11:56:41.960" LastActivityDate="2021-03-24T11:56:41.960" Title="How much time is a commercial aircraft (e.g. A320 / B737NG families) flown manually?" Tags="&lt;airline-operations&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26615" PostTypeId="2" ParentId="26614" CreationDate="2016-04-02T11:58:00.277" Score="15" Body="&lt;p&gt;Today's aircraft automation is just not set up for unattended operation.&lt;/p&gt;&#xA;&lt;p&gt;There are too many individual tasks, that pilots must complete, to list here. The lowest workload for pilots is during cruise but even then ATC can instruct you to change speed, routing, or altitudes. Maybe one day this could be controlled from the ground but today only the pilots can make those changes.&lt;/p&gt;&#xA;&lt;p&gt;I think you want to know how many minutes of an average flight are the pilots actually manipulating the controls either manually or through the A/P.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;The A/P comes on somewhere between 30 seconds and 7 mins after takeoff and it stays on continually for the whole flight until maybe 2 mins before touchdown.&lt;/p&gt;&#xA;&lt;p&gt;Every flight is different and sometimes there is lots of vectoring by ATC on departure/arrival and lots of step climb/descents, which requires the crew to &amp;quot;fly&amp;quot; the A/P. Sometimes the arrival/departure are linked up directly with the en route portion and you get a direct climb/descent.&lt;/p&gt;&#xA;&lt;p&gt;So as a rough guess on an average flight the pilots might &lt;strong&gt;manually fly the aircraft for about 3–10 minutes and &amp;quot;fly&amp;quot; the A/P for about 5–10 mins.&lt;/strong&gt; The rest of the time is spent talking to ATC, doing checklists, checking weather, fuel checks, and trying to keep yourself busy any other way you can think of. :)&lt;/p&gt;&#xA;&lt;p&gt;I personally fly mostly ultra long haul flights of 13–15 hours as part of a 4-man crew so I also spend about 6–7 hours sleeping in the bunk.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;In every phase of flight the crew is needed to do much more than just monitor the automation. The automation can not be used unless the pilots first enter all the required parameters, and then activate the automation at the right time, and in the correct order.&lt;/p&gt;&#xA;&lt;p&gt;There is no aircraft that can take off on autopilot. The autopilot can only be engaged after takeoff. Once airborne at cruising altitude the aircraft could follow a programmed flight routing but any change in heading, routing or altitude must be manually entered by the pilot.&lt;/p&gt;&#xA;&lt;p&gt;At the destination the approach must be manually programmed for the approach and runway in use. Once the aircraft in on the ILS approach an aircraft with autoland capability can land itself but it still needs the pilots to clear the runway.&lt;/p&gt;&#xA;&lt;p&gt;Autopilot/autothrottle policies can vary with each airline. Typically airline pilots hand fly from takeoff to at least 200' but many hand fly to 10,000' or more for practice. When landing most pilots hand fly from about 1,000'.&lt;/p&gt;&#xA;&lt;p&gt;Depending on the specific aircraft, autothrottle is usually engaged during the the takeoff roll and stays on until the flare just as it lands. There is no automation for landing gear and flap operation. It is 100% manual.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="14897" LastEditDate="2021-03-23T18:06:24.027" LastActivityDate="2021-03-23T18:06:24.027" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="26616" PostTypeId="1" CreationDate="2016-04-02T12:12:01.837" Score="3" ViewCount="590" Body="&lt;p&gt;I have been trying to estimate the lift calculation for a straight wing. The previous project I worked on was a swept wing. But this is a straight wing. I would like to to get the stall speed so I need the Clmax formula. What would the lift formula for this type of wing be?&lt;/p&gt;&#xA;" OwnerUserId="14287" LastEditorUserId="12220" LastEditDate="2016-04-02T12:18:30.970" LastActivityDate="2016-10-06T14:34:44.833" Title="What would be the lift formula for straight wings?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26617" PostTypeId="2" ParentId="26572" CreationDate="2016-04-02T13:10:47.717" Score="2" Body="&lt;h2&gt;Short Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Generally, no, but in at least one notable exception, &lt;strong&gt;Yes&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Longer Answer:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;@Dave has given a good answer that covers much of the industry. However, there is an industry sector for which the answer is, &quot;Yes&quot;: FAA certified &lt;a href=&quot;https://en.wikipedia.org/wiki/Light-sport_aircraft#United_States_-_FAA_certification&quot; rel=&quot;nofollow&quot;&gt;Special Light Sport Aircraft&lt;/a&gt; (S-LSA). These maintenance requirements are found in part 91, not—curiously enough—in part 43.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Firstly, the FAA gives manufacturers of S-LSA the authority to prescribe what must be done for routine maintenance and inspections. This authority is not absolute, as part 43 also applies and the role is also open to &quot;a person acceptable to the FAA&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=965c36f953afc298487d83aa7e90336d&amp;amp;mc=true&amp;amp;node=se14.2.91_1327&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.327&lt;/a&gt; (b) (1) and (2):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) No person may operate an aircraft that has a special airworthiness&#xA;  certificate in the light-sport category unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) The aircraft is maintained by a certificated repairman with a&#xA;  light-sport aircraft maintenance rating, an appropriately rated&#xA;  mechanic, or an appropriately rated repair station in accordance with&#xA;  the applicable provisions of part 43 of this chapter and maintenance&#xA;  and inspection procedures developed &lt;strong&gt;by the aircraft manufacturer&lt;/strong&gt; or a&#xA;  person acceptable to the FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) A condition inspection is performed once every 12 calendar months&#xA;  by a certificated repairman (light-sport aircraft) with a maintenance&#xA;  rating, an appropriately rated mechanic, or an appropriately rated&#xA;  repair station in accordance with inspection procedures developed &lt;strong&gt;by&#xA;  the aircraft manufacturer&lt;/strong&gt; or a person acceptable to the FAA;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In addition to this, manufacturers of S-LSA can issue Safety Directives, which are generally mandatory and can be thought of as roughly equivalent to &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/continued_operation/ad/&quot; rel=&quot;nofollow&quot;&gt;Airworthiness Directives (ADs)&lt;/a&gt;. Again, this power is not absolute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=965c36f953afc298487d83aa7e90336d&amp;amp;mc=true&amp;amp;node=se14.2.91_1327&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.327&lt;/a&gt; (b) (4):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(4) The owner or operator complies with each safety directive&#xA;  applicable to the aircraft that corrects an existing unsafe condition.&#xA;  In lieu of complying with a safety directive an owner or operator may—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Correct the unsafe condition in a manner different from that&#xA;  specified in the safety directive &lt;strong&gt;provided the person issuing the&#xA;  directive&lt;sup&gt;1&lt;/sup&gt; concurs with the action&lt;/strong&gt;; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) Obtain an FAA waiver from the provisions of the safety directive&#xA;  based on a conclusion that the safety directive was issued without&#xA;  adhering to the applicable consensus standard;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; &lt;sub&gt;&lt;em&gt;That is, the S-LSA manufacturer.&lt;/em&gt;&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, any repairs or alterations must be approved by the manufacturer, either by the existing manufacturer supplied Maintenance Manual, or on a case by case basis for those falling outside the scope of the Maintenance Manual. Once again, this power is not absolute; the FAA has to retain some authority. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=965c36f953afc298487d83aa7e90336d&amp;amp;mc=true&amp;amp;node=se14.2.91_1327&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.327&lt;/a&gt; (b) (5) and (6):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(5) Each alteration accomplished after the aircraft's date of&#xA;  manufacture meets the applicable and current consensus standard and&#xA;  has been authorized by either &lt;strong&gt;the manufacturer&lt;/strong&gt; or a person acceptable&#xA;  to the FAA;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(6) Each major alteration to an aircraft product produced under a&#xA;  consensus standard is authorized, performed and inspected in&#xA;  accordance with maintenance and inspection procedures developed &lt;strong&gt;by the&#xA;  manufacturer&lt;/strong&gt; or a person acceptable to the FAA; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also this article by D. Martino: &lt;a href=&quot;http://www.ussportaircraft.com/documents/CFI_guide_to_LSA_maintenance.pdf&quot; rel=&quot;nofollow&quot;&gt;Work Books: A flight instructor’s guide&#xA;to S-LSA maintenance regulations&lt;/a&gt;, which gives a good interpretation of these rules with less legalese.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-04-02T13:10:47.717" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26619" PostTypeId="1" AcceptedAnswerId="26620" CreationDate="2016-04-02T14:03:18.070" Score="5" ViewCount="319" Body="&lt;p&gt;Commercial airplanes sometimes suffer from a bird strike or something else that could ignite a part of the engine. So apart from noise insulation, do airliners have fire insulation?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="946" LastEditDate="2016-04-02T16:38:37.777" LastActivityDate="2016-04-02T16:38:37.777" Title="Do airplanes have any kind of fire insulation?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;fire&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26620" PostTypeId="2" ParentId="26619" CreationDate="2016-04-02T14:27:34.213" Score="6" Body="&lt;p&gt;Yes, aircraft have fire-protection systems as well with many of the materials being of such a sort.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/articles/2011_q4/4/&quot;&gt;boeing.com&lt;/a&gt; about the fire-resistant/fire-suppression systems on their aircraft. You can see that most of the aircraft is covered in these materials. Emphasis mine.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Interior components of Boeing airplanes meet flammability requirements prescribed in Title 14 Code of Federal Regulations (CFR) Part 25. These components include:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;- Interior ceiling.&#xA;- Interior sidewall panels.&#xA;- Partitions.&#xA;- Galley surfaces and structure.&#xA;- Exposed surfaces of stowed galley carts and standard galley containers.&#xA;- Large cabinets and cabin stowage compartments.&#xA;- Passenger seat material.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;  &#xA;  &lt;p&gt;For materials in areas not covered by the CFR requirements, Boeing design guidelines are used to identify additional flammability, smoke, and toxicity requirements.&#xA;  The standards for flammability of insulation blankets have improved over time. A recent requirement change calls for the enhancement of the fire-protective features of &lt;strong&gt;insulation blankets&lt;/strong&gt; in the event of an in-flight or post-crash fire. The latest standard increases protection by minimizing the contribution of the insulation blankets to the propagation of a fire. &lt;strong&gt;Thermal/acoustic insulation&lt;/strong&gt; installed behind cabin interior panels with the appropriate fire-resistant properties can delay the onset of fire into the cabin in the event of a crash (see fig. 1). &lt;strong&gt;&lt;em&gt;The insulation blankets, along with the airplane skin, must be capable of resisting burn-through from a fuel-fed post-crash fire next to the bottom half of the fuselage for a minimum of four minutes to allow passengers to evacuate the airplane before burn-through can occur.&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can also find out much more in that webpage about the various active and passive fire-suppression systems in aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA Regulation about these systems can be found &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch17.pdf&quot;&gt;here&lt;/a&gt; in PDF format.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-04-02T14:27:34.213" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26622" PostTypeId="2" ParentId="26594" CreationDate="2016-04-02T16:12:08.230" Score="4" Body="&lt;p&gt;There is nothing in the US regulations and no references that I can find that prohibits a pilot from learning to fly in a jet aircraft.  There are multiple systems on a jet aircraft that are not found in small GA aircraft and the same systems are more complex.  A lot of professional pilots who fly the same jet for a career don't fully understand the different systems on their jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The issue isn't with the FAA though; it is with the instructor and insurance companies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I certainly would not agree, as a CFII, to train a new student pilot in a jet.  I personally don't want to take on the liability for the payment I would receive for my services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most insurance companies will not ensure a student pilot to learn to fly in a jet.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="12220" LastEditDate="2016-04-02T17:30:43.537" LastActivityDate="2016-04-02T17:30:43.537" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26623" PostTypeId="2" ParentId="26611" CreationDate="2016-04-02T16:18:02.433" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.169&quot; rel=&quot;nofollow&quot;&gt;91.169&lt;/a&gt;, if the weather meets Basic VFR minima, you don't need an instrument approach to list it as an alternate.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;91.169(c)(2) &lt;strong&gt;If no instrument approach procedure has been published&lt;/strong&gt; in part 97&#xA;  of this chapter and no special instrument approach procedure has been&#xA;  issued by the Administrator to the operator, &lt;strong&gt;for the alternate&#xA;  airport, the ceiling and visibility minima are those allowing descent&#xA;  from the MEA, approach, and landing under basic VFR&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-02T16:18:02.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26624" PostTypeId="2" ParentId="26594" CreationDate="2016-04-02T16:36:23.247" Score="4" Body="&lt;p&gt;In theory, it is perfectly legal to do your primary training in a jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is becoming common in militaries to do initial training in turboprops. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airforce-technology.com/projects/t6b/&quot; rel=&quot;nofollow&quot;&gt;http://www.airforce-technology.com/projects/t6b/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Managing such a turboprop aircraft is actually simpler than managing your typical piston aircraft. One button start. One lever engine control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe some day that will become a single engine jet.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastEditorUserId="2129" LastEditDate="2016-04-02T19:34:38.337" LastActivityDate="2016-04-02T19:34:38.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26625" PostTypeId="1" AcceptedAnswerId="26630" CreationDate="2016-04-02T17:09:34.750" Score="49" ViewCount="5628" Body="&lt;p&gt;I was on a tour at the University of Maryland, and I saw these wings sitting against the wall:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/hHgmn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hHgmn.jpg&quot; alt=&quot; &quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I asked the guide, and he had no idea. (In case you can't tell these are two wings. The green lines indicate the extent of the two wings.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What aircraft do these belong to?&lt;/p&gt;&#xA;" OwnerUserId="580" LastEditorUserId="595" LastEditDate="2016-04-03T06:38:34.317" LastActivityDate="2016-07-24T05:21:13.563" Title="Does anybody recognize these wings?" Tags="&lt;wing&gt;&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26626" PostTypeId="1" AcceptedAnswerId="26632" CreationDate="2016-04-02T17:16:53.160" Score="2" ViewCount="6839" Body="&lt;p&gt;I am trying to solve some problems on converting from LMT (local mean time) to UTC (coordinated universal time) for flight planning purposes and I have some doubts. The problem is the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If the LMT in Delhi (LON=85ºE) is 17:45 (5:45 PM), what is the UTC?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First of all, what I've done is converting longitude into time as follows:&#xA;$$t=85\cdot4=340\hspace{1mm} min=5h\hspace{1mm}40m$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then, in order to compute the UTC time, what do I have to do, either adding up this time to the current LMT or subtract it (and what is the reason)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$UTC=Delhi(LMT)\pm t$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have checked a website that allows you to convert from LMT to UTC (&lt;a href=&quot;https://savvytime.com/converter/lmt-to-utc-india-delhi&quot; rel=&quot;nofollow&quot;&gt;https://savvytime.com/converter/lmt-to-utc-india-delhi&lt;/a&gt;) and I've seen the solution is 11:15 PM. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if I add or subtract my result, it is not the same as the given in the website. I suspect it is because in India they are using UTC +5:30 and probably these equations do not contemplate that, but I want to know the opinion of the experts anyway.&lt;/p&gt;&#xA;" OwnerUserId="8407" LastEditorUserId="19" LastEditDate="2016-07-11T14:20:13.463" LastActivityDate="2019-04-15T07:44:10.993" Title="How can LMT be converted to UTC time?" Tags="&lt;navigation&gt;&lt;time&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="26627" PostTypeId="1" AcceptedAnswerId="26673" CreationDate="2016-04-02T18:43:19.197" Score="8" ViewCount="2639" Body="&lt;p&gt;The fairings are painted red at the tips, look:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/C8DNo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C8DNo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://m.airliners.net/photo/detail/id/2722001&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen that on many new airplanes, not only the A330. So why are they painted red?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-04-02T23:33:33.677" LastActivityDate="2020-04-20T17:42:50.707" Title="Why are the tips of the flap track fairings painted red?" Tags="&lt;flaps&gt;&lt;paint&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26630" PostTypeId="2" ParentId="26625" CreationDate="2016-04-02T19:55:14.563" Score="112" Body="&lt;p&gt;Those wings are from an ERCO Ercoupe. The diagonal ribs are very distinctive. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BNQHf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BNQHf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wYmKn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wYmKn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uKVUz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uKVUz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BA9RZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BA9RZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9IeRT.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9IeRT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-02T19:55:14.563" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26632" PostTypeId="2" ParentId="26626" CreationDate="2016-04-03T00:41:24.323" Score="8" Body="&lt;p&gt;You have almost solved the problem yourself. The &lt;a href=&quot;https://savvytime.com/converter/lmt-to-utc-india-delhi&quot;&gt;website you linked to&lt;/a&gt; does not help you because, for some reason, it assumes &lt;a href=&quot;https://en.wikipedia.org/wiki/Local_mean_time&quot;&gt;Local Mean Time (LMT)&lt;/a&gt; to be equal to UTC. For your problem, LMT needs to be for 85° of East longitude. So, ignore that website and let's move on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For every degree of longitude, you calculate 4 minutes of difference from UTC. You have already correctly calculated the LMT difference from UTC for 85°E:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;First of all, what I've done is converting longitude into time as&#xA;  follows: $$t=85\cdot4=340\hspace{1mm} min=5h\hspace{1mm}40m$$&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This leaves you with the question of whether to add or subtract this difference, as you stated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But then, in order to compute the UTC time, what do I have to do, either adding up this time to the current LMT or subtract it (and what is the reason)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Let me start with the reason—the explanation of why we want to either add or subtract the difference between LMT and UTC—and then give you the solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LMT can be thought of as roughly equivalent to time based on the Sun's position. It is &lt;em&gt;not&lt;/em&gt; equivalent to that, which is &lt;a href=&quot;https://en.wikipedia.org/wiki/Solar_time&quot;&gt;Solar Time&lt;/a&gt;, but it is related. Keeping that approximation in mind, consider the difference in time between when the sun reaches solar noon over Delhi, and when the sun reaches solar noon over London. As the earth rotates, the sun reaches solar noon first over Delhi, and then, a few hours later, over London. Thus you know that UTC will be a few hours behind Delhi LMT. This means that you need to &lt;em&gt;subtract&lt;/em&gt; the calculated difference between LMT and UTC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to put this is: LMT for East longitude is ahead of UTC (subtract the difference to find UTC), and LMT for West longitude is behind UTC (add the difference to find UTC). Thus a more proper way to perform your calculation mathematically would be to properly incorporate the negative sign:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$t=-85\cdot4=-340\hspace{1mm} min=-5h\hspace{1mm}40m$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, if the LMT in Delhi (LON=85°E) is 17:45, then:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$UTC=12h05m$$ &lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-04-03T00:50:41.563" LastActivityDate="2016-04-03T00:50:41.563" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26633" PostTypeId="2" ParentId="26610" CreationDate="2016-04-03T04:16:32.420" Score="3" Body="&lt;p&gt;Yes, airplanes (all types including jets) can use window tints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Ultraviolet &quot;A&quot;&lt;/strong&gt;&lt;br&gt;&#xA;Tints for airplanes are with enhanced protection from UVA radiation. UVA exposure can increase the risk of skin cancer and will damage most organic materials. Its intensity increases about 5% with every 1000 feet of altitude. Unlike car tints, airplane tints need to block the additional exposure to UVA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Solar Energy Control&lt;/strong&gt;&lt;br&gt;&#xA;Tints also block near-infrared radiation which results in lesser interior heat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;LP Aero Plastics (&lt;a href=&quot;http://www.aircraftspruce.com/catalog/appages/lpaero.php&quot; rel=&quot;nofollow&quot;&gt;product listing&lt;/a&gt;) and &lt;a href=&quot;http://www.sdplastics.com/polycastaerospaceacrylicsheet.html&quot; rel=&quot;nofollow&quot;&gt;PolyOne&lt;/a&gt; are the two manufactures I found for aircraft tints.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-04-03T04:16:32.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26636" PostTypeId="1" AcceptedAnswerId="26639" CreationDate="2016-04-03T13:27:18.440" Score="21" ViewCount="3328" Body="&lt;p&gt;Sometimes airline pilots need to get in touch with their company while in the air, for example diagnosing cautionary messages or reporting a diversion. By what means is the communication channel established?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;VHF / HF radio? If that's the case, who allocates the frequencies to each airline?&lt;/li&gt;&#xA;&lt;li&gt;Satellite phone? (Are all aircrafts equipped with one in the cockpit?)&lt;/li&gt;&#xA;&lt;li&gt;Something else?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2021-03-26T17:29:51.917" Title="How do airline pilots contact their company while in the air?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;radio-communications&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26639" PostTypeId="2" ParentId="26636" CreationDate="2016-04-03T16:18:06.967" Score="21" Body="&lt;p&gt;While enroute the primary communication with company is via ACARS. (Aircraft Communications Addressing and Reporting System)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a digital datalink system and is kind of like sending text messages. On modern aircraft like a B777 it operates on HF, VHF, or SATCOM so there is coverage almost anywhere in the world.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft is close to an airport with a company frequency, regular VHF radio communication can also be used.  Some airlines may even have company Peripheral stations (PAL) at certain locations so they can use a VHF radio to talk directly to Dispatch from hundreds of miles away.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the USA, VHF company frequencies are allocated by Aviation Spectrum Resources, Inc. (ASRI) &lt;a href=&quot;https://www.asri.aero/our-services/asri-ground-station-administration-service/&quot; rel=&quot;noreferrer&quot;&gt;ASRI Ground Station Administration Service (AGSA)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;SATCOM is also be used to make Satellite phone calls so we can talk directly to Dispatch or Maintenance from thousands of miles away. You can use pre-selected company numbers or manually enter any phone number.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft without SATCOM can use VHF or HF radios to contact ARINC (Aeronautical Radio, Incorporated) who can create a phone patch to any phone number.  &lt;a href=&quot;https://en.wikipedia.org/wiki/ARINC&quot; rel=&quot;noreferrer&quot;&gt;Aeronautical Radio, Incorporated (ARINC)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GdJhD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GdJhD.jpg&quot; alt=&quot;SATCOM phone number menu&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: B777 Aircraft Operating Manual Volume 2 (2.23 Communications)&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-04T18:46:01.953" LastActivityDate="2016-04-04T18:46:01.953" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26640" PostTypeId="2" ParentId="17370" CreationDate="2016-04-03T16:24:24.963" Score="0" Body="&lt;p&gt;Teetering rotors are 'underslung' to maintain a constant center of mass during the flapping cycle. Lead-lag movements are not required, so long as the rotor is coned to a certain degree. Twin bladed tail rotors are delta hinged to provide lead lag. Augusta helicopters have pre-coned tail rotors and are both underslung and delta. &lt;/p&gt;&#xA;" OwnerUserId="14304" LastActivityDate="2016-04-03T16:24:24.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26641" PostTypeId="2" ParentId="12952" CreationDate="2016-04-03T17:11:54.767" Score="4" Body="&lt;p&gt;Yes. Someone can (and unfortunately has) opened an aircraft door while still armed. Some aircraft have an indicator that is visible from the outside indicating the door is still armed. Other aircraft require indincation from flight attendants (such as a thumbs up) indicating the door is disarmed. Older single isle aircraft  (727 DC-9) the slides would fall out of slide pack but not inflate. Flight attendants would have to pull an inflation handle at the part of the slide attached to the floor of the aircraft after opening the aircraft door. This was an economic feaure for airlines as slide deployment are expensive. If the slide deploys but not inflated they were just rolled back into the protective covering.  However these were dangerous in actual emergencies as flight attendants would have to reach down and inflate slides and could be pushed out. The ones that automatically inflate are dangerous if opened accidentally if they are deployed into a jetwat or catering vehicle &lt;/p&gt;&#xA;" OwnerUserId="14305" LastActivityDate="2016-04-03T17:11:54.767" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26642" PostTypeId="2" ParentId="26517" CreationDate="2016-04-03T19:32:32.907" Score="3" Body="&lt;p&gt;While the others answers are completely correct regarding the ability of the Hondajet (and any other twin jet, for that matter) to safely fly after an engine failure (including during the takeoff roll past V1,) it's probably also worth pointing out that &lt;strong&gt;you don't need any engines to safely land from cruising altitude&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engines are generally needed to climb or maintain altitude, but you can glide with no engines at all. According to &lt;a href=&quot;http://www.hondajet.com/hondajet/Specifications&quot; rel=&quot;nofollow&quot;&gt;Honda's website&lt;/a&gt;, the Hondajet has a maximum cruise altitude of 43,000 ft and has a cruise speed of 420 KTAS if cruising at 30,000 ft. Even if you lost both engines at 30,000 ft., you'd almost certainly be able to glide around a hundred miles and still land safely. From 43,000 ft. it would probably be well over 100 miles. This would be true for almost any commercial or private jet aircraft.&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2016-04-03T19:39:49.917" LastActivityDate="2016-04-03T19:39:49.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26643" PostTypeId="2" ParentId="26295" CreationDate="2016-04-03T19:37:00.393" Score="6" Body="&lt;p&gt;An airman can close an IFR flight plan at airports without continuously operating towers using the clearance delivery frequency.&lt;/p&gt;&#xA;" OwnerUserId="12288" LastEditorUserId="12288" LastEditDate="2020-02-10T21:36:08.007" LastActivityDate="2020-02-10T21:36:08.007" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="26644" PostTypeId="2" ParentId="26276" CreationDate="2016-04-03T19:45:11.570" Score="5" Body="&lt;p&gt;These are latches holding the engine support pylon panel in closed. Behind this panel is the diagonal brace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This area was modified ~1992 due to the &lt;a href=&quot;https://en.wikipedia.org/wiki/El_Al_Flight_1862&quot; rel=&quot;nofollow noreferrer&quot;&gt;El Al Flight 1862&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/China_Airlines_Flight_358&quot; rel=&quot;nofollow noreferrer&quot;&gt;China Airlines Flight 358&lt;/a&gt; crashes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://archive.is/B1GhD#selection-24.0-33.15&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Lessons Learned&lt;/a&gt; (via archive.is).&lt;/p&gt;&#xA;" OwnerUserId="12288" LastEditorUserId="14897" LastEditDate="2018-06-09T16:37:40.687" LastActivityDate="2018-06-09T16:37:40.687" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26645" PostTypeId="1" CreationDate="2016-04-03T21:33:31.327" Score="10" ViewCount="1607" Body="&lt;p&gt;In IFR-GPS-equipped (/G) aircraft, a pilot flies most of the segments with GPS as primary navigational resource* even the route is along victor airways or VOR radials. However, when we start the approach, we have to switch the nav source from GPS to the nav source specified for the approach. In this context of using GPS for non-GPS approaches, &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;When should a pilot switch away from GPS? Is it from an IAF, FAF or upon ATC vectors to intercept the final approach course?&lt;/li&gt;&#xA;&lt;li&gt;If the a pilot executes a missed approach, when can the pilot switch back to GPS? Is it when established on course direct to the holding fix?&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;*By primary navigational resource, I mean it provides the signal/data source for the CDI needle on a HSI, that a pilot, autopilot or flight director refers to make actions or action suggestions.&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-04-03T21:38:43.100" LastActivityDate="2016-04-03T22:06:39.200" Title="In what portion a non-GPS approach, can a pilot legally fly with GPS as primary navigational resource?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26646" PostTypeId="2" ParentId="26645" CreationDate="2016-04-03T22:06:39.200" Score="10" Body="&lt;p&gt;An appropriately installed GPS may be used until crossing the final approach fix on a non-localizer approach, and until the segment requiring navigation via the localizer on a LOC, ILS, SDF, or LDA approach. It's generally approved and legal at any other time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the missed approach, a pilot may switch to GPS immediately, unless the missed approach requires navigating by using the localizer, in which case the ground-based navaid must continue to be used until the procedure no longer requires navigation by reference to the localizer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA covers this in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/90-108.pdf&quot;&gt;AC 90-108&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An otherwise &#xA;  suitable RNAV system cannot be used for the following:&lt;br&gt;&#xA;  &lt;strong&gt;a.   NOTAMed   Procedures.&lt;/strong&gt; &#xA;  Unless otherwise specified, navigation on procedures that are &#xA;  identified as not authorized (“NA”) without &#xA;  exception by a NOTAM. For example, an operator &#xA;  may not use a RNAV system to navigate on a procedure affected by an expired or unsatisfactory &#xA;  flight inspection, or a procedure that is based upon a &#xA;  recently decommissioned NAVAID.&lt;br&gt;&#xA;  &lt;strong&gt;b.   Substitution on a Final Approach Segment.&lt;/strong&gt; &#xA;  Substitution for the NAVAID (for &#xA;  example, a VOR or NDB) providing lateral &#xA;  guidance for the final approach segment.&lt;br&gt;&#xA;  &lt;strong&gt;c. Lateral Navigation on LOC-Based Courses.&lt;/strong&gt;&#xA;   Lateral navigation on LOC-based courses &#xA;  (including LOC back-course guidance) &#xA;  without reference to raw LOC data. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="136" LastActivityDate="2016-04-03T22:06:39.200" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26647" PostTypeId="2" ParentId="25316" CreationDate="2016-04-03T23:44:32.020" Score="1" Body="&lt;p&gt;Let's extract some abbreviations from &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.185&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.185 (c) (3)&lt;/a&gt;, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ECL: En-route clearance limit&lt;/li&gt;&#xA;&lt;li&gt;EFC: Expected further clearance&lt;/li&gt;&#xA;&lt;li&gt;IAF: Initial approach fix, a fix from which an approach&lt;/li&gt;&#xA;&lt;li&gt;ETA: Estimated time of arrival, adjusted by departure time offset and superseded by most recent ATC amendment.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and expand the four possible concrete scenarios regarding how to commence   the approach to the destination airport.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;ECL is a IAF with EFC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;En-Route → ECL/IAF (Hold until EFC) → Descent and approach&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ECL is a IAF without EFC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;En-Route → ECL/IAF (Hold until ETA) → Descent and approach&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ECL is not a IAF with EFC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;En-Route → ECL (Hold until EFC) → IAF (Hold until ETA) → Descent and approach &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ECL is not a IAF without EFC:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;En-Route → ECL → IAF (Hold until ETA) → Descent and approach &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2016-04-03T23:44:32.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26648" PostTypeId="1" AcceptedAnswerId="26649" CreationDate="2016-04-04T00:54:40.163" Score="26" ViewCount="6290" Body="&lt;p&gt;On the tail section of the YF-22 further back in the image below, there is a red canister. What is that canister for? I suppose it is for some flight testing purposes from what I can see.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OOCck.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OOCck.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;I can't pinpoint the image source.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-05-13T05:39:56.983" Title="What is this red canister on the tail of the YF-22?" Tags="&lt;experimental-aircraft&gt;&lt;f-22&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26649" PostTypeId="2" ParentId="26648" CreationDate="2016-04-04T00:57:40.643" Score="29" Body="&lt;p&gt;It is a spin recovery/stabilization chute, installed during testing for high AoA test flights. The following image shows it being deployed on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/97p0Y.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/97p0Y.jpg&quot; alt=&quot;spin chute&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://fas.org/man/dod-101/sys/ac/f-22-19990727stabilization-chute-test.jpg&quot; rel=&quot;noreferrer&quot;&gt;fas.org&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="11390" LastEditDate="2016-04-04T07:46:06.050" LastActivityDate="2016-04-04T07:46:06.050" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26651" PostTypeId="2" ParentId="26522" CreationDate="2016-04-04T10:33:22.250" Score="1" Body="&lt;p&gt;There are lots of factors playing into a pilot's decision as to which airfield to divert to.  Typically this will include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Where that airline has a ground team e.g. a Easyjet flight inbound to Gatwick is unlikely to divert to Heathrow because it won't have any staff on the ground to deal with passengers, and it costs a hell of a lot to hire someone else's team!&lt;/li&gt;&#xA;&lt;li&gt;What are the landing conditions at the diversion airfield e.g. if there is low visibility and fog at Charles De Gaulle, then the same weather might be present at Orly&lt;/li&gt;&#xA;&lt;li&gt;The length of the runway - most passenger jets (say B737 and above) are going to be too large/heavy to be able to land at London City, so they'll choose to divert elsewhere&lt;/li&gt;&#xA;&lt;li&gt;And, of course, how much fuel is left on the aircraft!  Pilots will want to have enough fuel to be able to safely abort one landing, circle the airfield and try again - as an absolute bare minimum.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;As for fuel minima - it varies a bit from country to country and airline to airline, but a general rule of thumb is that the flight should have enough fuel to hold in a stack for a reasonable time (20-30 minutes at Heathrow), attempt a landing, &lt;em&gt;and&lt;/em&gt; divert to their declared alternate.  So, if you're going to make the decision to divert early, then you could feasibly travel a good extra distance in pursuit of one of the items listed above.&lt;/p&gt;&#xA;" OwnerUserId="14235" LastActivityDate="2016-04-04T10:33:22.250" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26652" PostTypeId="2" ParentId="26648" CreationDate="2016-04-04T10:50:16.567" Score="46" Body="&lt;p&gt;The canister contains a small parachute and either a spring or an explosive charge to kick the chute out when it is needed. It is a precaution for spin flight tests, that's why it is called a spin chute. See here for a &lt;a href=&quot;https://www.youtube.com/watch?v=aBxaDkXHzKY&quot; rel=&quot;nofollow noreferrer&quot;&gt;video of the spin chute of the F-35&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess now I should explain how a spin chute works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an aircraft &lt;a href=&quot;https://aviation.stackexchange.com/questions/3484/how-is-a-wing-designed-to-be-stall-or-spin-proof/3486#3486&quot;&gt;spins&lt;/a&gt;, it will rotate around a vertical axis which is somewhere between slightly ahead of the aircraft (regular spin) or near the leading edge (flat spin). The pitch angle &lt;span class=&quot;math-container&quot;&gt;$\Theta$&lt;/span&gt; is nose down and the angle of attack &lt;span class=&quot;math-container&quot;&gt;$\alpha$&lt;/span&gt; is high (around 45° in a regular spin, up to 90° in a flat spin), so the airflow over most of the wing and horizontal tail is separated. But the rotation, which is a mix of rolling and yawing, will induce an angle of attack variation over span, so a part of one wing will operate in the normal angle of attack range, where lift is high and drag is low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now we have a receding wing with separated flow, at high angle of attack, with low lift and high drag so the resulting air force vector R (green, below) points mostly into the direction of local flow (which is up). The other wing has partially attached flow, a lower angle of attack, high lift and moderate drag, so the resulting air force vector is almost perpendicular to the local flow, pointing up and forward. This difference in lift and drag propels the rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/57rXU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/57rXU.png&quot; alt=&quot;Speeds and resulting force on spinning wing sections&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speeds and resulting force on spinning wing sections. &lt;span class=&quot;math-container&quot;&gt;$\omega_z$&lt;/span&gt; is the rotation speed around the vertical axis, y is the local wing station and the green v shows the local flow direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Without the rotation the aircraft would immediately pitch nose down, pick up speed and can be pulled out of the resulting dive. With the rotation, however, we get an inertial pitch moment due to the fuselage masses. All parts of the aircraft rotate with the same yaw rate, and the centrifugal force from this yawing motion grows linearly with distance from the spin axis. This difference in centrifugal force along the lengthwise coordinate of the aircraft adds a powerful nose-up moment which in some cases cannot be overcome by the tail surfaces - remember, they have less effectivity in separated flow. &lt;a href=&quot;https://aviation.stackexchange.com/questions/2170/is-it-possible-to-recover-from-a-flat-spin/8590#8590&quot;&gt;Flat spins are almost impossible to escape from&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://aviation.stackexchange.com/questions/21646/why-cant-model-aircraft-be-used-to-discover-spin-and-stall-behavior-of-manned-a/21662#21662&quot;&gt;can be tested in spin tunnels&lt;/a&gt;, but Murphy's Law is very relevant to spin tests. So it is a good precaution to add a spin chute for the first tests: If the aircraft cannot &lt;a href=&quot;https://aviation.stackexchange.com/questions/11246/what-is-the-beggs-mueller-emergency-spin-recovery-technique/11256#11256&quot;&gt;end the spin with control surface deflections&lt;/a&gt;, it is in a trap from which it can only escape with something that will add a strong nose-down moment. In the chaotic airflow behind a rapidly spinning airplane. That is why the spin chute is not bolted to the skin of the airplane, but sits in an elevated position hanging out at the back. From there it will not be caught by the tail surfaces but will work as intended in all conceivable situations (save an inverted spin ...)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-05-13T05:39:56.983" LastActivityDate="2020-05-13T05:39:56.983" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="26653" PostTypeId="1" AcceptedAnswerId="26659" CreationDate="2016-04-04T10:54:27.217" Score="6" ViewCount="1546" Body="&lt;p&gt;I understand that if I am tracking a radial inbound I will set that radial as the reciprocal so I don't have to worry about reverse sensing. On an approach however, do I need to set the CDI to the reciprocal? If I go missed and track the same course outbound do I then leave the CDI on the same heading? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On this approach plate, which was talked about &lt;a href=&quot;https://aviation.stackexchange.com/questions/1096/why-do-some-back-course-operations-use-normal-sensing&quot;&gt;here&lt;/a&gt;, why is the back course on two different sides (one is shaded on the left, one is shaded on the right)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iEUu1.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iEUu1.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does a front course and a back course affect your CDI settings?&#xA;&lt;a href=&quot;https://i.stack.imgur.com/40ISV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/40ISV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any difference between these two CDIs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jlsKB.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jlsKB.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/5E5Ow.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5E5Ow.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(And also, why is it labeled a VOR receiver? I thought both of these instruments were called Course Deviation Indicators.&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-04-05T18:38:59.793" Title="When do I need to worry about a course deviation indicator reverse sensing?" Tags="&lt;instrument-flight-rules&gt;&lt;flight-instruments&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26654" PostTypeId="1" CreationDate="2016-04-04T10:59:47.743" Score="5" ViewCount="158" Body="&lt;p&gt;My understanding of precision was both lateral and vertical guidance. If a GPS approach with WAAS provides both, why is it still considered non-precision?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-04-04T10:59:47.743" Title="Why is an LPV WAAS GPS approach considered non-precision?" Tags="&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2016-04-04T13:57:51.193" ContentLicense="CC BY-SA 3.0" />
  <row Id="26655" PostTypeId="1" AcceptedAnswerId="26671" CreationDate="2016-04-04T11:04:14.237" Score="4" ViewCount="308" Body="&lt;p&gt;I had always been taught to begin a descent from TPA abeam the touchdown point, even if tower tells me to follow another aircraft. Yesterday I flew with an instructor who did not want me to descend from TPA until abeam the aircraft I was following. I understand that I begin my base turn when the aircraft I am following is abeam my wing. I did not know to also wait until then to descend from TPA. It does make more sense to stay at TPA until this point but I can't find anything saying one way or the other. &lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-04-05T14:13:03.997" Title="In a pattern, when do you begin your descent from TPA if following another aircraft?" Tags="&lt;traffic-pattern&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26656" PostTypeId="1" AcceptedAnswerId="26663" CreationDate="2016-04-04T11:33:05.637" Score="9" ViewCount="28649" Body="&lt;p&gt;When flying a procedure turn like the one shown below, the first step is to fly outbound 039 degrees. When you turn inbound to 219 degrees, do you make that turn to the left or to the right? The left meaning to turn to the outside of the procedure turn (a greater distance from the FAF) and the right meaning to turn to the inside of the procedure turn (a shorter distance from the FAF). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Q72Ax.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q72Ax.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at these pictures, it looks like the procedure turn is made outwards from the course:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/1y4JO.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1y4JO.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11402" LastEditorUserId="69" LastEditDate="2016-04-04T20:35:35.443" LastActivityDate="2018-08-31T00:13:03.160" Title="On a procedure turn, do you make the turn on the inside or outside of the procedure turn?" Tags="&lt;faa-regulations&gt;&lt;instrument-procedures&gt;&lt;terps&gt;" AnswerCount="5" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26657" PostTypeId="2" ParentId="26522" CreationDate="2016-04-04T11:42:44.583" Score="4" Body="&lt;p&gt;I won't reply to the &quot;is it possible the flight was diverted this far&quot; bit, as other have given good reasons for this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, even though we're missing quite a bit of data, it seems quite obvious that &lt;strong&gt;this specific flight was never diverted&lt;/strong&gt;: the AMS-GDN flight got out of range of FR24 on approach to GDN, and somehow FR24 took the following flight (from GDN to somewhere else, probably Krakow) as the continuation of this flight. Full data history would probably show a big gap in the data between the two sharp &quot;turns&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is consistent with:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the times shown (ETA 9:09 PM CET, actual time 21:47 UTC which is 10:47 PM CET, well into the next flight),&lt;/li&gt;&#xA;&lt;li&gt;the actual paths which are clearly aligned with GDN (both inbound and outbound),&lt;/li&gt;&#xA;&lt;li&gt;the fact that the &quot;turns&quot; are way too sharp,&lt;/li&gt;&#xA;&lt;li&gt;recent flight history for the aircraft (which flies GDN-KRK on a very regular basis)&lt;/li&gt;&#xA;&lt;li&gt;the absence of any other aircraft on the map in the GDN area&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Remember this is a Dash 8, which is not equipped with ADS-B, but a simpler Mode-S transponder, which requires multilateration (MLAT) and hence to be visible from at least 4 stations to show up on the FR24 map, and provides less data.&lt;/p&gt;&#xA;" OwnerUserId="3313" LastEditorUserId="3313" LastEditDate="2016-04-04T12:31:22.220" LastActivityDate="2016-04-04T12:31:22.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26658" PostTypeId="1" CreationDate="2016-04-04T11:50:16.537" Score="0" ViewCount="97" Body="&lt;p&gt;I hold a LSA license wit 200 hours. I am currently doing my PPL and I was wondering if any of the SLA hours can count for some of my PPL training hours? What are the regulations?&lt;/p&gt;&#xA;" OwnerUserId="14317" LastEditorUserId="1467" LastEditDate="2016-04-04T12:00:37.280" LastActivityDate="2016-04-04T12:00:37.280" Title="Does LSA hours count towards PPL training hours" Tags="&lt;flight-training&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-04-04T14:00:05.213" ContentLicense="CC BY-SA 3.0" />
  <row Id="26659" PostTypeId="2" ParentId="26653" CreationDate="2016-04-04T11:55:43.870" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;On this approach plate, which was talked about here, why is the back course on two different sides (one is shaded on the left, one is shaded on the right)?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The 108.5 IPKN localizer is there only to mark safe path out for missed approach procedure and is intended to be flown outbound, so it has the signal swapped so it indicates normally when flown outbound.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does a front course and a back course affect your CDI settings?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It does not affect &lt;em&gt;settings&lt;/em&gt; of &lt;em&gt;CDI&lt;/em&gt; at all, because ILS does not take the OBS course into account. It indicates left when it senses more of the left signal and right if it senses more of the right signal, independent of anything else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What it affects is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The left signal is on the left when flying the normal direction and this applies both before and after the transmitter. So when you fly in opposite direction, the left signal is on the right from your point of view, causing the reverse sensing.&lt;/li&gt;&#xA;&lt;li&gt;With HSI you can compensate for it by selecting the normal course in the OBS. The instrument then still senses the same, but the instrument is now upside down, negating the reverse sensing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are there any difference between these two CDIs?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, since these are both CDIs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a difference if you have HSI:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Horizontal_situation_indicator-en.svg#/media/File:Horizontal_situation_indicator-en.svg&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Horizontal_situation_indicator-en.svg/1200px-Horizontal_situation_indicator-en.svg.png&quot; alt=&quot;Horizontal situation indicator-en.svg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The difference between CDI and HSI is that on CDI the needle always moves left-right, indicating whether your position is left or right of the selected radial (via OBS for VOR, but fixed for ILS) independent on direction you are flying. So if you are actually flying the opposite direction, you must steer the other way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In contrast the inner part of HSI rotates with compass, always pointing the arrow in the selected direction. This has two advantages:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;you see how your direction of flight relates to the selected heading and&lt;/li&gt;&#xA;&lt;li&gt;when you are flying in the opposite direction (backcourse), the needle is upside-down, negating the reverse sensing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And also, why is it labeled a VOR receiver?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Because it is (also) used to display VOR signal. Both CDI (where the needle always moves left-right) and HSI (where the inner part with the needle rotates with compass) are VOR indicators.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that almost always the same tuner is used to receive VOR and ILS signals and the same instrument is used to display them though the processing logic is different (VOR detects phase while ILS detects differences in the depth of modulation from the two signals).&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="5568" LastEditDate="2016-04-05T18:38:59.793" LastActivityDate="2016-04-05T18:38:59.793" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26663" PostTypeId="2" ParentId="26656" CreationDate="2016-04-04T16:00:25.930" Score="8" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_4-03-14.pdf&quot;&gt;Section 5-4-9 of the AIM&lt;/a&gt; contains a lot of guidance on procedure turns, and says (in short):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If the procedure turn is charted as a teardrop or hold-in-lieu of procedure turn, then it must be flown as charted. (Does not apply in this case.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If it is a standard procedure turn, the barbed arrow shows the maneuvering side (so the first turn should be flown as indicated), but the rest of the procedure is at the discretion of the pilot, as long as they stay within the distance specified on the chart.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I was taught (and see it as a &quot;standard practice&quot;) to turn away from the fix defining the start of the procedure turn for the 180 degree turn, and in fact have never seen anyone fly it the other way.  That being said, there is nothing which prevents it if it can be done within the protected area and accomplishes the purpose of becoming established on the final approach course in time.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;A small excerpt from the AIM (lots more information is available there):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5−4−9. Procedure Turn and Hold−in−lieu of Procedure Turn&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;On U.S. Government charts, a barbed arrow indicates the maneuvering side of the outbound course on which the procedure turn is made.&#xA;  Headings are provided for course reversal using the 45 degree type&#xA;  procedure turn. However, the point at which the turn may be commenced&#xA;  and the type and rate of turn is left to the discretion of the pilot&#xA;  (limited by the charted remain within xx NM distance). Some of the&#xA;  options are the 45 degree procedure turn, the racetrack pattern, the&#xA;  teardrop procedure turn, or the 80 degree  260 degree course&#xA;  reversal. Racetrack entries should be conducted on the maneuvering&#xA;  side where the majority of protected airspace resides. If an entry&#xA;  places the pilot on the non−maneuvering side of the PT, correction to&#xA;  intercept the outbound course ensures remaining within protected&#xA;  airspace. Some procedure turns are specified by procedural track.&#xA;  These turns must be flown exactly as depicted.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-04-04T16:30:18.210" LastActivityDate="2016-04-04T16:30:18.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26664" PostTypeId="2" ParentId="26656" CreationDate="2016-04-04T16:31:19.240" Score="4" Body="&lt;p&gt;In the FAR's it is left up to the pilot how to perform the turn. You just have to do it on the correct side of the approach coarse and stay within the protected area.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In your instrument training, your instructor may have insisted that you fly a standard barbed PT just as it's depicted. Nothing wrong with that. But you don't have to do it that way. Both the FAA's Instrument Flying Handbook and the AIM say that &quot;the point at which the turn may be commenced and the type and rate of turn is left to the discretion of the pilot.&quot; Besides the standard 45-180, you can also fly a 90-270 or what some pilots call the 40-second turn, which consists of an abbreviated 45-degree outbound turn to compensate for the effects of a tailwind. &#xA;  &lt;a href=&quot;http://www.avweb.com/news/system/183196-1.html&quot; rel=&quot;nofollow&quot;&gt;www.avweb.com&lt;/a&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;as long as the pilot stays on the side of the procedure turn barb, inside the protected airspace determined by distance or time and does not exceed the maximum holding airspeed you may fly the course reversal as desired.&#xA;  &lt;a href=&quot;http://aviationtrainingus-rob.blogspot.com/2009/05/do-i-have-to-fly-instrument-procedure.html?m=1&quot; rel=&quot;nofollow&quot;&gt;aviationtrainingus-rob.blogspot.com&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That said, the usual way is to the outside of the procedure. That would give you more distance for the approach.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-04-04T16:31:19.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26665" PostTypeId="2" ParentId="26596" CreationDate="2016-04-04T16:46:55.567" Score="3" Body="&lt;p&gt;Jet powered aircraft use feeder tanks to stabilize the flow of fuel to engines and APUs.  These feeder tanks are pressurized and kept full to a specific amount to ensure fuel flow (for a certain period of time).  The feeder tanks are fed by a system of transfer pumps from the main tanks, which in turn are pressurized (usually with an inert gas mixture).  Unlike most gravity fed tanks, the tank is not drained via a single sump type arrangement, but a more complicated series of apertures for fuel to flow into the feeder (which may include in tank pumps).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I cannot speak exactly to this aircraft, it is usually the case that special mission aircraft have fuel systems modified or designed to suit their needs.  This aircraft may have a larger feeder tank or a different feeder tank design that allows for extended periods of low-g operation.  Generally speaking, low-g operation does not have an affect on pressurized fuel systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Much of the information you seek is provided by the FAA here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_ch14.pdf&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_ch14.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14322" LastActivityDate="2016-04-04T16:46:55.567" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26666" PostTypeId="2" ParentId="26656" CreationDate="2016-04-04T17:06:29.080" Score="4" Body="&lt;p&gt;&quot;&lt;em&gt;a barbed arrow indicates the maneuvering side of the outbound course on which the procedure turn is made&lt;/em&gt;&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That only means the procedure must be flown on the east side of the outbound course. &lt;strong&gt;It does not tell you which way to turn after flying 039 degrees.&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;JEPP charts show the entire loop on a procedure turn and they never turn towards the FAF. The turn is always away from the FAF.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if you believe that turning right after 039 degrees would keep you in the maneuvering area, do not do it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No one does it that way and if you are flying with someone else in the flight deck they will question your sanity and not want to fly with you again. :) &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-04T18:34:35.777" LastActivityDate="2016-04-04T18:34:35.777" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26667" PostTypeId="1" AcceptedAnswerId="26668" CreationDate="2016-04-04T17:23:23.697" Score="6" ViewCount="1180" Body="&lt;p&gt;Angle of attack is the angle between the chord line of the wing to the direction of relative wind. So angle of attack helps the aircraft climb.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Then what is the angle between the chord line of the elevator and relative wind? Because if I am not wrong, by pitching the elevator up, the wing of an aircraft is subjected to the 'angle of attack'. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When you say angle of attack exceeds the critical angle of attack, is it because the elevator is pitched up thus creating wider angle between the chord line and the relative direction of the wind?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the Air France 447 accident, the PF kept saying, &lt;a href=&quot;https://www.bea.aero/uploads/tx_elyextendttnews/annexe.01.en.pdf&quot; rel=&quot;nofollow&quot;&gt;keeps the wings level&lt;/a&gt;. What does it mean? How can the wings be leveled when the angle of attack is so high? Does keeping the wings level mean reducing the angle of attack to zero?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="4197" LastEditDate="2016-04-06T09:21:47.920" LastActivityDate="2016-04-06T09:21:47.920" Title="What are the definitions of elevator angle of attack and critical angle of attack?" Tags="&lt;wing&gt;&lt;angle-of-attack&gt;&lt;elevator&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26668" PostTypeId="2" ParentId="26667" CreationDate="2016-04-04T17:38:23.160" Score="2" Body="&lt;p&gt;Angle of Attack is the angle between the chord line of the &lt;strong&gt;airfoil&lt;/strong&gt; and the relative wind. The elevator is also a &quot;wing&quot; in the effect that it is an airfoil.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1) Then what is the angle between the chord line of the elevator and relative wind? Because if I am not wrong, by pitching the elevator up, the wing of an aircraft is subjected to the 'angle of attack'.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It's also called &quot;Angle Of Attack&quot;. Pitching the elevator up also changes the angle of attack of the elevator. There are such conditions as elevator stall, although much less common than wing stall.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;2) When you say angle of attack exceed critical angle of attack, is it because the elevator is pitched up thus creating wider angle between the chord line and the relative direction of the wind?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &quot;Critical AoA&quot; is the angle at which the airfoil is generating the most lift. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[&lt;a href=&quot;https://en.wikipedia.org/wiki/Angle_of_attack&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia Article on AoA&lt;/a&gt;]: The critical angle of attack is the angle of attack which produces maximum lift coefficient. This is also called the &quot;stall angle of attack&quot;. Below the critical angle of attack, as the angle of attack increases, the coefficient of lift (Cl) increases. At the same time, above the critical angle of attack, as angle of attack increases, the air begins to flow less smoothly over the upper surface of the airfoil and begins to separate from the upper surface&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Usually when you exceed the critical AoA, the air on the upper surface of the airfoil de-laminates and becomes turbulent. This results in a loss of lift (stall). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/spVdz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/spVdz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.flightsimbooks.com/flightsimhandbook/CHAPTER_02_16_Basic_Aerodynamics.php&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source: FlightSimBooks.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3)In the Air France 447 accident, the PF kept saying, keeps the wings level. What does it mean? How can the wings be leveled when the angle of attack is so high? Does keeping the wings level means reducing the angle of attack to zero?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I'm not sure what context you are talking about. I've read the transcripts pretty carefully and I don't recall the PF saying to keep the wings level. The Captain said to descend, while the PF was trying to climb. The SIC was pushing the stick forward while the PF was pulling back, causing the wings to remain level (or at a slight climb). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keeping the wings level (avoiding an un-coordinated turn) in a stall condition is the best way to avoid putting the aircraft into a spin. This is possibly what they meant, although they didn't know that they were in a stall (or if they did, they were not reacting to it appropriately).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, leveling the wings would be making the AoA at zero (zero meaning where the airfoil is developing lift, and depending on the bank angle), but only if there were positive airspeed to make the relative wind parallel with the chord. In the case of AF447, the aircraft was falling out of the sky at a spectacular 15,000 FPM, which means that the relative wind to the airfoil was basically perpendicular. They didn't have the forward airspeed to change the AoA, so they should have lowered the nose to gain airspeed and decrease the AoA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The important thing to remember is that the pitch angle of the aircraft is not the same as the AoA. You can take an aircraft at zero forward speed and drop it straight down, the pitch angle will be zero but the AoA will be perpendicular. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="1467" LastEditDate="2016-04-04T19:31:22.333" LastActivityDate="2016-04-04T19:31:22.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26669" PostTypeId="1" AcceptedAnswerId="26670" CreationDate="2016-04-04T18:12:06.980" Score="31" ViewCount="11149" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/q/8840/8730&quot;&gt;this question&lt;/a&gt; it is mentioned that the fan, compressor and turbine blades are mounted loosely in the disc. This is well demonstrated by &lt;a href=&quot;https://youtu.be/6ZVaeP1fE6w&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt; posted by RedGrittyBrick. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-06T11:40:19.317" Title="Why are the fan blades mounted loosely?" Tags="&lt;turbofan&gt;&lt;blade&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26670" PostTypeId="2" ParentId="26669" CreationDate="2016-04-04T19:37:09.187" Score="27" Body="&lt;p&gt;The blades are loose in their &quot;Fir Tree&quot; blade mounts so that they can self balance. They are called &quot;fir tree&quot; because they are v shaped.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the rotation speed and centrifugal force increases, they move in the mounts and establish individual lead/lag positions to achieve a balanced disc. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It will be understood that turbine wheels rotate at very high speeds&#xA;  of rotation, thereby generating large centirfugal forces tending to&#xA;  throw the blades outwardly from the wheel. By providing contact&#xA;  surfaces of equal and opposite slope with respect to the longitudinal&#xA;  axis of the root on opposite sides of root, the force components of&#xA;  the centrifugal force balance each other out. Periodic and other&#xA;  vibrations which might otherwise be generated are damped out and&#xA;  greatly minimized&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.google.ca/patents/US3045968&quot; rel=&quot;noreferrer&quot;&gt;Fir tree blade mount Patent &lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nQPcC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nQPcC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/JA3lZ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JA3lZ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZvFNz.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZvFNz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-04T20:00:34.740" LastActivityDate="2016-04-04T20:00:34.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26671" PostTypeId="2" ParentId="26655" CreationDate="2016-04-04T21:31:35.467" Score="3" Body="&lt;p&gt;Every CFI I have ever flown with has a different procedure for when to descend. Its annoying. Think of it as descending to the runway when you are in a position to land. If you are not following another aircraft, then you can begin your descent abeam the threshold. If you are following another aircraft, then you should wait to descend until you are in a position to land as #2, which could be after you've already turned base or (long) final.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-04-05T14:13:03.997" LastActivityDate="2016-04-05T14:13:03.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26672" PostTypeId="1" CreationDate="2016-04-04T22:44:02.547" Score="1" ViewCount="811" Body="&lt;p&gt;Software developed for aircraft needing TA certification pretty much has to be done using a process following RTCA/DO-178C.  My question regards low-level (sometimes called &quot;derived&quot;) requirements:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low-level requirements either refine high-level requirements, or express design decisions.  I've been told a low-level requirement should be traceable to some statement or small block of code, and at DAL C and above, each piece of code needs to be traceable to a low-level requirement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do DERs want to see a test corresponding to each low-level requirement, or is that only so for the high-level requirements?  Would it be OK to do testing at a function level (&quot;unit testing&quot;) as low-level requirement testing, and are the DERs happy with that?&lt;/p&gt;&#xA;" OwnerUserId="12120" LastEditorUserId="1467" LastEditDate="2016-04-05T07:46:37.247" LastActivityDate="2016-11-11T19:54:36.473" Title="What do FAA DERs require regarding low-level requirements in DO-178C?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;software&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26673" PostTypeId="2" ParentId="26627" CreationDate="2016-04-05T00:02:51.297" Score="7" Body="&lt;p&gt;Elaborating on &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%C3%A4mpf&quot;&gt;Peter Kämpf&lt;/a&gt;'s comment: The flashy tips are for preventing accidents during ground handling operations, e.g. by belt loaders. This can be a painting or an adhesive tape (possibly reflective, useful at night).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According the pages referenced below, this is done for the A320 family aircraft for which the flap track canoe fairings are not low enough to be obvious, not high enough to not cause a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems this is a company decision not required by regulation. Several airlines do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Variations on the painting (taping):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Only the fairings close to the locations where ground handling personnel works.&lt;/li&gt;&#xA;&lt;li&gt;Only the right side of the aircraft.&lt;/li&gt;&#xA;&lt;li&gt;Also the winglet.&lt;/li&gt;&#xA;&lt;li&gt;Color used: Red, bright pink, reflective green.&#xA;&lt;BR&gt;&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8R3vz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8R3vz.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Photo &lt;a href=&quot;http://www.airliners.net/search/photo.search?photographersearch=Taha%20Ashoori%20-%20Iranian%20Spotters&quot; rel=&quot;nofollow noreferrer&quot;&gt;Taha Ashoori&lt;/a&gt; on Airliners.net (&lt;a href=&quot;http://www.airliners.net/photo/Mahan-Air/Airbus-A310-308/1685000/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;BR&gt;&#xA;&lt;a href=&quot;https://www.flickr.com/photos/vlk77/24703438381/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nyNgA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Photo &lt;a href=&quot;http://Vin%20Lane-Kieltyka&quot; rel=&quot;nofollow noreferrer&quot;&gt;Vin Lane-Kieltyka&lt;/a&gt; on Flickr (&lt;a href=&quot;https://www.flickr.com/photos/vlk77/24703438381/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/wZBog.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wZBog.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://gofar.aircanada.com/en/go-far-answers/question/what%E2%80%99s-that-green-tape-around-the-wings-and-winglets-of-air-canada%E2%80%99s-airbus-fleet/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;References (non authoritative):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Air Canada Flap Track Fairing Speed Tape? (&lt;a href=&quot;http://7.airliners.net/aviation-forums/tech_ops/read.main/328619&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Why Do Airliners Paint Trailing Edge Flap Fairing (&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/279964&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;li&gt;Colour On Flap Track Fairings (&lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/362588/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-05T13:23:26.407" CommentCount="0" CommunityOwnedDate="2016-04-05T00:02:51.297" ContentLicense="CC BY-SA 3.0" />
  <row Id="26674" PostTypeId="2" ParentId="26669" CreationDate="2016-04-05T00:08:39.677" Score="14" Body="&lt;p&gt;There are a few reasons for assembling the blades loosely in the gas turbine engine.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The loose attachment of the fan blades allow for the easy installation/removal of the fan blades.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Though the blades are loose while the blades are stationary, as the engine start spinning, the centrifugal force pushes the blades out and as a result, they will not be so loose. Still, the blades can move slightly in their attachments in order to dampen the vibration.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another thing is that the blades (especially turbine blades) undergo thermal expansion, in which case they may warp if there is no space for expansion.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-05T00:08:39.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26675" PostTypeId="2" ParentId="26627" CreationDate="2016-04-05T04:20:13.680" Score="0" Body="&lt;p&gt;When Southwest Airlines started flying Boeing 737 Next Generation, many years ago, now, they used the same red as on the underside of their &quot;Corndog&quot; scheme for the flap track fairings of the NG models. So ground crew would easily know whether they were receiving a &quot;Classic&quot; or an &quot;NG&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1897" LastActivityDate="2016-04-05T04:20:13.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26680" PostTypeId="2" ParentId="11237" CreationDate="2016-04-05T14:10:19.040" Score="4" Body="&lt;p&gt;Answering an old question but there are issues with the winch launch that have not been covered; one is a wing drop on the ground run. If the wing touches the ground while being winched then the glider can cartwheel if the pilot is not quick enough or able to pull the cable release. The winch can keep pulling the aircraft until the winch operator spots a problem and stops the launch or the pilot pulls the release.&#xA;This happened at my club about 3 years ago (2012) with an experienced pilot in a Nimbus 3. He died of his injuries.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also the possible issue with cable fouling, although unlikely it is possible in a shallow fast climb to dip the nose on release and impact the cable if the cable parachute has opened. That will ruin your day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pulling too far back on the stick on the ground run can cause an overly-quick rotation into a steep climb causing the tail to hit the ground. While removal of the tail will reduce drag considerably it will cause one of two control issues.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In winch launches you are very much at the mercy of your ground crew and winch driver. All it takes is for a misheard instruction or someone to mistake the glider model and you could be launched on the wrong winch setting. An underpowered or overpowered launch can cause a lot of problems for a pilot but then that is why we drill for problems. I have to admit to signalling a launch for the wrong type of glider, thankfully it was spotted by the pilot who radioed a correction but I have seen gliders launched on the incorrect winch setting on a few occasions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots of Petrol Pigeons don't have a cable to worry about.&lt;/p&gt;&#xA;" OwnerUserId="14127" LastActivityDate="2016-04-05T14:10:19.040" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26682" PostTypeId="2" ParentId="26596" CreationDate="2016-04-05T17:26:36.127" Score="26" Body="&lt;p&gt;I wrote an email to AirZeroG and asked them:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Other than the interior, are your aircraft modified in any way to handle zero-g flight?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Here is the response that they gave me:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dear Sir,&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Except free floating area cabin configuration, there are very few differences with a “standard aircraft”. The most significant one is installation of Zero-G meters in cockpit and a very simple installation on the wheels to help one pilot to lead the aircraft only in vertical axis, and the other pilot to lead only in horizontal axis.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Out of that, the biggest difference is maintenance program: each parabola performed to create Zero G onboard is considered as an aircraft cycle for the aircraft and its engines, and maintenance adjusted accordingly. Such consideration dramatically increases maintenance costs of the aircraft.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Kind regards&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Gilles GOMPERTZ&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I would say that &lt;em&gt;if&lt;/em&gt; there were a fuel system difference they would say that is more significant than G-Meters in the cockpit. I'm assuming based on the response above that the fuel storage/delivery system is unmodified. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-05T17:36:42.663" LastActivityDate="2016-04-05T17:36:42.663" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26683" PostTypeId="1" AcceptedAnswerId="26685" CreationDate="2016-04-05T18:24:04.520" Score="6" ViewCount="1966" Body="&lt;p&gt;For an IFR currency flight in a high-performance and/or complex airplane where the pilot flying has all the appropriate ratings and endorsements to be PIC, does another pilot with strictly a private ASEL certificate meet the legal requirements to be the safety pilot?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, I would assume the entire flight must be conducted in VMC. What other constraints or restrictions apply in such a scenario?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If permissible, how may the safety pilot log the flight so as to count toward future ratings and so on?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-04-06T04:29:52.677" LastActivityDate="2019-06-08T05:41:06.043" Title="May a VFR-only pilot without high-performance or complex endorsements be the safety pilot for an IFR currency flight?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;logging&gt;&lt;safety-pilot&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26684" PostTypeId="2" ParentId="26683" CreationDate="2016-04-05T19:35:12.220" Score="2" Body="&lt;p&gt;61.31 requires these endorsements for the legal pilot in command only.  If the safety pilot is not the legal pilot in command the endorsements are not required.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only requirement is for the safety pilot to be appropriately rated and have a current medical.  See 91.109&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-04-05T19:35:12.220" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26685" PostTypeId="2" ParentId="26683" CreationDate="2016-04-05T19:44:37.637" Score="6" Body="&lt;p&gt;First, can a pilot without an HP endorsement act as safety pilot in an HP aircraft? Since &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1109&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.109&lt;/a&gt; only requires a safety pilot to have category and class ratings, there's no need to have any additional endorsements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's confirmed in &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/1991/rizner%20-%20(1991)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this FAA legal interpretation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;there is no regulatory requirement that a safety pilot have a&#xA;  high performance endorsement to act as safety pilot&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The same document says that safety pilots are &quot;encouraged to be thoroughly familiar and current in the aircraft that is used&quot; - which is great advice - but that's it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the flight conditions (IMC/VMC) and rules (IFR/VFR), I'm not sure what you're asking. Is either pilot IFR current? If not, then the flight can only be VFR. &lt;a href=&quot;https://aviation.stackexchange.com/q/23810/62&quot;&gt;This question&lt;/a&gt; might be relevant.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="14661" LastEditDate="2019-06-08T05:41:06.043" LastActivityDate="2019-06-08T05:41:06.043" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="26686" PostTypeId="1" CreationDate="2016-04-05T19:53:49.757" Score="17" ViewCount="7796" Body="&lt;p&gt;When taking off, why are we required to climb at least 35 feet over the departure end of runway? Why not other numbers? This comes from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?mc=true&amp;amp;node=se14.1.25_1111&quot;&gt;the FAA regulations&lt;/a&gt;. I believe there must a clear explanation for this but can't find one. Is there any historical or mathematical reason?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="1696" LastEditDate="2016-04-06T15:51:32.293" LastActivityDate="2020-07-08T01:16:44.180" Title="Where does the 35 feet screen height come from?" Tags="&lt;faa-regulations&gt;&lt;takeoff&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26687" PostTypeId="2" ParentId="26669" CreationDate="2016-04-05T21:03:55.220" Score="20" Body="&lt;p&gt;I's like to expand the answers on how this could reduce vibrations, as it was mentioned in a comment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, I'd like to look at something completely different: When computers were equipped with faster and faster CD-ROM drives, the reduction of vibrations caused by small imbalances in the discs became more and more important. The solution is is shown below. The spindle which sets the CD into rotation contains a circular shaped grove with a few metal balls, which can move freely in the grove. It looks a little like a ball bearing which lost some balls:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/i7tny.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/i7tny.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://technikwissen.rde.de/cd-dvd-unwucht.html&quot;&gt;Source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's consider there are just four balls. If the disc  is perfectly balanced, the balls will arrange themselves so that all centrifugal forces (black arrows) point away from the axis of rotation and cancel out each other. The center of gravity (COG) is located on the geometrical center, which is also the axis of rotation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Xqqxo.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xqqxo.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now let's consider some imbalance, modeled as additional mass here, which will shift the COG away from the geometrical center towards this mass (My library put barcode stickers on their CDs...)&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If the disc could rotate freely, it would rotate around its new COG.&lt;/li&gt;&#xA;&lt;li&gt;If the support of the spindle is absolutely rigid, it forces the disc to rotate around its geometrical center, though the imbalance exerts a centrifugal force and heavy vibration on the support.&lt;/li&gt;&#xA;&lt;li&gt;If the support is flexible, it will follow the centrifugal force of the imbalance at low RPMs. (Left animation)&lt;/li&gt;&#xA;&lt;li&gt;At higher RPMs, something strange happens: The spindle starts to act as counterbalance for the imbalance, and the disc rotates around a point &lt;em&gt;between&lt;/em&gt; the COG and the geometrical center. Yet, the movement of the spindle exerts forces, i.e. vibration on the support. (Right animation)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/F9YgS.gif&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/F9YgS.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a resonance effect and a bit hard to understand. Maybe, an analog: Hold a spring with a weight at the lower end. When you move your hand up and down slowly, the weight will follow your movement exactly. But when you move your hand much faster than the resonance frequency of the system, your hand an the weight will always move in opposite directions. (I guess, this still does not make it clear, but I have no better explanation...)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However... What happens to the balls?&lt;br&gt;&#xA;I have drawn the centrifugal forces (black) on the four balls in my last point / right animation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4LSMb.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4LSMb.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The disc rotates around the green x instead around the geometrical center (red +). The centrifugal forces point away from the green x. With respect to the geometrical center, the force on the upper and lower ball can be dissected into a radial (gray) and tangential (magenta) component. As the balls can move freely in the grove, they will follow the tangential force to the right. This means, some mass shifts from the left to the right side and as consequence, the COG and the axis of rotation are  much closer to the geometrical center.&lt;br&gt;&#xA;Finally, this principle can eliminate the vibration to a large extent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Coming back to a fan&lt;/strong&gt;, the loosely mounted blades act like the balls. As the fan is for sure already well balanced, it is sufficient if they can just tilt a little in their position.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="4170" LastEditDate="2016-04-06T11:40:19.317" LastActivityDate="2016-04-06T11:40:19.317" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26688" PostTypeId="2" ParentId="516" CreationDate="2016-04-05T22:01:08.433" Score="6" Body="&lt;p&gt;I would request flight following on most flights, short or long as soon as practical, which means, on the ground (with ground control) or if at an uncontrolled airport after I have finished flying the plane safely out of the pattern and started navigating to my destination (even if I am not at cruising altitude yet).  If you talk to ATC and they are too busy, they will let you know that they are too busy, But most air traffic controllers  would much rather have radio contact with you, then not be in radio contact and try to guess what you are doing.  For example you are flying vor outside their controled airspace and are ascending to your planned flight altitude, mean while, a wide body commercial plane is descending across your flight path.  It is easier, quicker and safer to talk to you about keeping your current altitude until advised, or change your heading then have to divert a wide body plane around you which is on an IFR flight plan because you did not see them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You get the added safety of another set of eyes looking out for you (some of the time as work load permits) and they get communication with you and an ability to move you around to increase safety.  They get another piece on the board that they can legally control, that they normally have no control over.  It is a Win for both sides.&lt;/p&gt;&#xA;" OwnerUserId="14343" LastActivityDate="2016-04-05T22:01:08.433" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26690" PostTypeId="1" AcceptedAnswerId="26691" CreationDate="2016-04-06T00:41:29.090" Score="9" ViewCount="471" Body="&lt;p&gt;To be considered a safety pilot, must the aviator in question be able to manipulate the flight controls, or is see-and-avoid responsibility sufficient?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Asked another way, if the PIC wants to fly under simulated instrument conditions to maintain currency in a Cessna 172, is the lone pilot seated in the rear a safety pilot or a passenger? Did the PIC bring along one safety pilot or two?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-04-06T00:53:19.353" LastActivityDate="2016-04-06T01:41:00.463" Title="Is a certificated pilot in a rear seat with no access to flight controls a safety pilot or a passenger?" Tags="&lt;faa-regulations&gt;&lt;safety-pilot&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26691" PostTypeId="2" ParentId="26690" CreationDate="2016-04-06T01:24:16.033" Score="9" Body="&lt;p&gt;After looking through the FAR's, the answer is no, the rear passenger seat cannot be occupied by somebody claiming to be a &quot;safety pilot&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10.2.4.5&amp;amp;rgn=div8&quot;&gt;FAR 91.109(c)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) No person may operate a civil aircraft in simulated instrument flight unless—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&amp;nbsp;&amp;nbsp;(1) &lt;strong&gt;The other control seat is occupied by a safety pilot&lt;/strong&gt; who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.&lt;br/&gt;&lt;br/&gt;&#xA;  &amp;nbsp;&amp;nbsp;(2) The safety pilot has &lt;strong&gt;adequate vision forward and to each side of the aircraft&lt;/strong&gt;, or a competent observer in the aircraft adequately supplements the vision of the safety pilot; and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis Mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the safety pilot basically has to be able to access the controls &lt;strong&gt;and&lt;/strong&gt; have vision that supplements the pilot, meaning must be able to see as well as the pilot position would.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="7532" LastEditDate="2016-04-06T01:41:00.463" LastActivityDate="2016-04-06T01:41:00.463" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26692" PostTypeId="1" AcceptedAnswerId="33364" CreationDate="2016-04-06T01:56:17.970" Score="5" ViewCount="336" Body="&lt;p&gt;Can a pilot use a VLD for IFR currency if the aircraft requires two pilots? Can it be used while carrying passengers? If so, is this ever done?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm thinking of part 121 airline pilots under FAA.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-11-23T10:04:43.237" Title="Can a view limiting device be used in an aircraft requiring two pilots?" Tags="&lt;faa-regulations&gt;&lt;ifr-navigation&gt;&lt;currency&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26693" PostTypeId="2" ParentId="26669" CreationDate="2016-04-06T03:04:52.123" Score="1" Body="&lt;p&gt;You need to realize just how big the radial force on each blade (caused by the rotating shaft) actually are, when the engine is running at in its normal operating speed range. Those centripetal and centrifugal forces are literally thousands of times the weight of the blades. On each fan blade of a large turbofan engine, the radial load on the blade root is more than 100 tons (or tonnes, for non-US readers). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no practical way that you could clamp up the blades with forces as large as that when you assembled them, even if there was any point in doing so. It's more sensible to design the fan so that is easy to assemble, and let it clamp itself rigidly when it is operating. The only disadvantage is that if the rotor is turning very slowly, you can often hear individual &quot;clicks&quot; from the blades moving about as they rotate, which can frighten the uninitiated.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2016-04-06T03:04:52.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26695" PostTypeId="1" AcceptedAnswerId="26747" CreationDate="2016-04-06T03:58:05.563" Score="7" ViewCount="2385" Body="&lt;p&gt;I have known two types IFR clearance that a pilot may request with flight plan filing.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pop-up clearance: A pilot on VFR requests an IFR clearance to destination airport. ATC grants a clearance on a work-load permit basis.&lt;/li&gt;&#xA;&lt;li&gt;IFR Climb to VFR-on-top: A pilot may obtain this type of clearance from ground clearance delivery and the clearance limit is usually a nearby Nav aid.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The unlikely clearance without pre-filed plan is,&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airport-to-airport: Ask ground clearance delivery for an IFR clearance to another airport.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;What other types of IFR clearance else may I request ATC directly? We know that the flight plan checked-in time needs to 30 min prior to its start time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;IFR-descent-to-VFR-under-bottom&quot;: Is it possible to request an IFR descent through a cloud layer, say 8000 to 5000 through a layer 6000~7000? Is it just one special case of &quot;pop-up clearance&quot;, or due to the descent nature, ATC won't grant it?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there any concrete regulations or general conventions that a pilot may follow?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2016-04-07T19:05:50.263" Title="What IFR clearances may a pilot obtain from ATC directly without a pre-filed flight plan with FSS?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;clearance&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26696" PostTypeId="1" CreationDate="2016-04-06T04:12:33.093" Score="2" ViewCount="819" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.newsweek.com/boeings-737-airplane-prone-problems-63629&quot; rel=&quot;nofollow&quot;&gt;this Newsweek article&lt;/a&gt; - which seems like a reputable source - the FAA has issued a number of Airworthiness Directives to address stress fatigue concerns with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;nofollow&quot;&gt;737NG series&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Between 2000 and 2011, as the number of NG series in the air grew to&#xA;  more than 2,000, I identified 13 directives that specifically&#xA;  concerned cracking and fatigue issues in the model’s fuselage.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article focuses on potential issues with the aft pressure bulkhead:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;But the most alarming alert concerned involved a repeatedly troubled&#xA;  area called the aft pressure bulkhead (the rear portion of the cabin).&#xA;  In an Airworthiness Directive dated Nov. 5, 2001, the agency called&#xA;  for “immediate corrective action” to deal with a flaw in the aft&#xA;  pressure bulkhead [...] Four airlines had discovered, during&#xA;  checks, that if a 737 made a hard landing, damaging the main landing&#xA;  gear, or simply a certain kind of hard landing that led to shimmying,&#xA;  involving violent swerves on the runway (not uncommon in turbulent&#xA;  weather), the forces transmitted from that impact would end up&#xA;  damaging the aft pressure bulkhead, fatally jeopardizing the tailfin.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;There were five alerts about problems with this bulkhead. [Prof. Tony] &#xA;  Ingraffea, after looking at the [details], told me in an&#xA;  email: “Skin cracking and aft bulkhead problems are clearly chronic.”&#xA;  [...]&#xA;  In a written memo to Newsweek,&#xA;  Boeing claimed that to say that there were “persistent problems” with&#xA;  the bulkhead is “not correct” but did not elaborate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on the number of ADs (and any other relevant information), is Newsweek accurate in claiming that the 737 is more susceptible to stress fatigue than other, similar aircraft? Is the number of ADs for this issue unusual? Is there any measurably higher risk associated with flying in a 737 because of this issue?&lt;/p&gt;&#xA;" OwnerUserId="14350" LastEditorUserId="22726" LastEditDate="2019-02-04T06:20:57.157" LastActivityDate="2019-02-04T06:20:57.157" Title="Is the Boeing 737 unusually susceptible to stress fatigue?" Tags="&lt;safety&gt;&lt;boeing-737&gt;&lt;fatigue&gt;" AnswerCount="0" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26697" PostTypeId="1" CreationDate="2016-04-06T07:05:55.080" Score="6" ViewCount="274" Body="&lt;p&gt;I came across this question while studying stalling of airfoils. How does the chord length of an airfoil affect the position of the separation point of flow?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flow_separation&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Flow_separation&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Wikipedia article on flow separation isn't very clear on what is the relation between location of separation point and Reynolds Number (and thus Chord Length). &lt;/p&gt;&#xA;" OwnerUserId="14351" LastEditorUserId="12220" LastEditDate="2016-04-06T23:45:19.437" LastActivityDate="2016-04-06T23:45:19.437" Title="How is flow separation related to the chord length of an airfoil?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26701" PostTypeId="1" CreationDate="2016-04-06T10:00:18.487" Score="4" ViewCount="175" Body="&lt;p&gt;What are the factors a pilot needs to consider before preparing for the steep approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is steep approach combined with auto land feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yBgbv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yBgbv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="11517" LastEditDate="2016-04-07T06:06:53.183" LastActivityDate="2016-04-07T06:06:53.183" Title="What are the driving factors for performing a steep approach" Tags="&lt;aircraft-systems&gt;" AnswerCount="0" CommentCount="10" ClosedDate="2016-04-06T20:09:23.470" ContentLicense="CC BY-SA 3.0" />
  <row Id="26702" PostTypeId="1" CreationDate="2016-04-06T10:22:09.047" Score="5" ViewCount="1374" Body="&lt;p&gt;Winglets have been discussed &lt;a href=&quot;https://aviation.stackexchange.com/questions/2111/what-do-winglets-do-to-increase-aircraft-performance&quot;&gt;fairly&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/19541&quot;&gt;regularly&lt;/a&gt;, but not much can be found on the topic of endplates. What are endplates, how do they work, and how do they relate to winglets?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-08T07:21:21.470" Title="What are endplates? How do they work?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26703" PostTypeId="1" AcceptedAnswerId="26705" CreationDate="2016-04-06T12:19:33.233" Score="10" ViewCount="5201" Body="&lt;p&gt;I have been watching a few aircraft landing videos in crosswind situations and I noticed that if the airliner missed the runway the landing gear would go back into the aircraft. So I'm wondering if this system is automatic after a takeoff or if it's controlled by the pilot manually?&lt;/p&gt;&#xA;" OwnerUserId="9716" LastActivityDate="2016-04-07T08:38:30.503" Title="Is the landing gear controlled by the pilot or is it automatic?" Tags="&lt;landing-gear&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26704" PostTypeId="2" ParentId="26703" CreationDate="2016-04-06T12:25:27.910" Score="6" Body="&lt;p&gt;All landing gear that I know of are all controlled by the pilots. I have never heard of an &quot;automatic landing gear&quot; as you describe it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As some comments below say, there is one airplane that has/had an automatic gear (Piper Arrow) but it was not really the brightest idea because it could cause in-flight problems if not handled properly.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-06T15:00:53.833" LastActivityDate="2016-04-06T15:00:53.833" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26705" PostTypeId="2" ParentId="26703" CreationDate="2016-04-06T12:28:06.957" Score="17" Body="&lt;p&gt;The landing gear system is operated by the pilots. The extension and retraction, depend on the action from the pilot monitoring, on 2 pilots operation.&#xA;The pilot has a lever on their panel, on which they select the extension (down) and/or retraction (up).&#xA;Some aircraft has a system to avoid extending them on high speed, to avoid some damage, and on the ground, avoiding retracting, for obvious reasons.&#xA;There are lights, green and red, indicating their position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qKidl.png&quot; rel=&quot;noreferrer&quot; title=&quot;courtesy code7700.com&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qKidl.png&quot; alt=&quot;enter image description here&quot; title=&quot;courtesy code7700.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14354" LastActivityDate="2016-04-06T12:28:06.957" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26707" PostTypeId="2" ParentId="26703" CreationDate="2016-04-06T12:45:26.797" Score="2" Body="&lt;p&gt;As the other answers point out, it generally is operated by the pilots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &lt;a href=&quot;http://www.aerodays2015.com/wp-content/uploads/sites/20/4G-Reimund-Kueke.pdf&quot; rel=&quot;nofollow&quot;&gt;last project&lt;/a&gt; I have participated in, though, flap and gear control was performed by an automated system (see slide 17). The control system was automatically deploying the flaps and gear at a specified location during the final approach, without any pilot intervention.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the future there might be more aircraft that will use such automation, but not before the appropriate amendments will be done to the regulations and not before one such system will be succesfully certified.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-04-06T12:45:26.797" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26708" PostTypeId="2" ParentId="26703" CreationDate="2016-04-06T12:49:38.333" Score="7" Body="&lt;p&gt;It's manual. Once there is positive climb the pilot will retract the gear &lt;a href=&quot;https://aviation.stackexchange.com/q/26536/609&quot;&gt;and flaps&lt;/a&gt; to minimize drag.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-04-06T12:49:38.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26709" PostTypeId="1" AcceptedAnswerId="26710" CreationDate="2016-04-06T15:03:51.127" Score="14" ViewCount="8159" Body="&lt;p&gt;I see &lt;a href=&quot;https://aviation.stackexchange.com/questions/22385/why-do-military-turbofan-engines-use-a-low-bypass-ratio&quot;&gt;some&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/12977/can-the-thrust-of-a-turbofan-be-increased-by-increasing-bypass-ratio&quot;&gt;questions on&lt;/a&gt; &lt;a href=&quot;https://aviation.stackexchange.com/questions/11586/what-is-a-high-bypass-geared-turbofan-and-why-is-it-so-much-more-efficient&quot;&gt;the site&lt;/a&gt; that talk about the relative positives and negatives of a high bypass turbofan (HB) vs a low bypass turbofan (LB).  But I don't see anything explaining what actually makes a turbofan engine HB or LB?  I assume it has to do with the ratio of air that is bypassing the compressor stages and just going through the fans.  But what ratio makes an engine HB v. LB?  And why was that ratio chosen?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Please note: I am not looking for usage cases, I am looking for differences in design specifications.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-04-06T21:30:51.257" Title="What is the difference between a high bypass turbofan and a low bypass turbofan?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26710" PostTypeId="2" ParentId="26709" CreationDate="2016-04-06T16:15:29.583" Score="13" Body="&lt;p&gt;The first turbofan, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Conway&quot;&gt;RR Conway&lt;/a&gt;, had just a bypass ratio of 0.25. It was designed for installation into the wing root of airplanes like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Handley_Page_Victor&quot;&gt;HP Victor&lt;/a&gt; bomber or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Vickers_V-1000&quot;&gt;Vickers V-1000&lt;/a&gt; transport project, so RR strived to keep the diameter small. Of course, back then nobody distinguished low- and high-bypass engines. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT3D&quot;&gt;P&amp;amp;W JT-3D&lt;/a&gt;, which powered most of the second generation of jet airliners (Boeing 707 and DC-8), had a bypass ratio of less than 1.5.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when the new generation of engines (&lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_CF6&quot;&gt;GE CF-6&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D&quot;&gt;JT-9D&lt;/a&gt;) with bypass ratios of around 5 were developed for the first generation of wide body jets, marketing needed a term to make clear that this was a new generation of engines, and the high-bypass ratio engine category was born. Generally, the threshold is around 5, but note that some CF-6 versions have bypass ratios as low as 4.24 and still fall into the high bypass ratio category. Therefore, &lt;a href=&quot;https://en.wikipedia.org/wiki/Category:High-bypass_turbofan_engines&quot;&gt;Wikipedia&lt;/a&gt; sets the limit at a bypass ratio of 4.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no technical difference between a low- and a high-bypass engine, and the limit is arbitrary. The jump in bypass ratio from 1.5 to 5 brought significant improvements in specific fuel consumption and noise reduction, but part of the technical progress was also from better materials and aerodynamics, which allowed higher compression ratios and turbine entry temperatures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, almost 50 years later, we see the first engines with &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000&quot;&gt;bypass ratios above 10&lt;/a&gt; entering service. Designs are being readied with bypass ratios of 12, so marketing will need a new word to describe those creations. With &quot;ultra high bypass&quot; already taken by the &lt;a href=&quot;https://en.wikipedia.org/wiki/Propfan&quot;&gt;unducted fan&lt;/a&gt; crowd, the search is on.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-04-06T21:30:51.257" LastActivityDate="2016-04-06T21:30:51.257" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26711" PostTypeId="2" ParentId="26709" CreationDate="2016-04-06T16:26:39.660" Score="8" Body="&lt;p&gt;There is no particular ratio at which the engine becomes a 'high' bypass, though the it is generally taken to be around ~5:1. The reasons are more historic than technical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first large scale development of the high-bypass turbofans was spurred by the USAF's CX-HLS competition, which lead to the C-5 Galaxy. The requirements of the competition (range and fuel efficiency) lead to the development of a new generation of engine by GE and PW, which developed the TF39 and JTF14E respectively. GE won the contract with the TF39 engine, which had a previously unheard of 8:1 bypass ratio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PW figured out that it better develop a high bypass engine itself or lose the market and developed the JT9D, which had a 5:1 bypass ratio. This engine was the first widely used engine with high bypass ratio (the previous engine had bypass ratios in the range of ~1 or so) and necessitated a special mention, which came to be called high-bypass engines, once it became widely used, especially in the Boeing 747 (Ironically, it was the two losers of the CX-HLS competition PW and Boeing, which won the immediate race in civil aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Joe Sutter acknowledged the effect of the CX competition in the &lt;a href=&quot;http://www.seattlepi.com/business/article/Aerospace-Notebook-Man-behind-the-747-tells-his-1193757.php&quot;&gt;development of 747&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I should add that fostering large high-bypass engines was all that the USAF C-5 competition contributed to the Boeing 747, as my new airplane would be called. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not to be left behind, GE developed the CF6 series with bypass ratios of 6:1 and RR developed the RB211-22 which had a bypass ratio of ~5:1. Due to these, the ratio of around 5:1 (or &gt;4:1) is usually taken as the dividing line between the 'high' and 'low' bypass ratio turbofans.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-06T16:26:39.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26712" PostTypeId="1" AcceptedAnswerId="26718" CreationDate="2016-04-06T17:34:18.490" Score="10" ViewCount="652" Body="&lt;p&gt;This question came up as a followon to &lt;a href=&quot;https://aviation.stackexchange.com/a/26691/2143&quot;&gt;another answer&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=260e87b2919c6aa5b5a87561f779ed6f&amp;amp;mc=true&amp;amp;node=sp14.2.91.b&amp;amp;rgn=div6#se14.2.91_1109&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.109&lt;/a&gt; reads in part, with added emphasis:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;§91.109 Flight instruction; Simulated instrument flight and certain flight tests.&lt;/h3&gt;&#xA;&lt;p&gt;(c) No person may operate a civil aircraft in simulated instrument flight unless—&lt;/p&gt;&#xA;&lt;p&gt;    (1) The other control seat is occupied by a safety pilot who possesses at least a private pilot certificate with category and class ratings appropriate to the aircraft being flown.&lt;/p&gt;&#xA;&lt;p&gt;    (2) The safety pilot has adequate vision forward and to each side of the aircraft, or a &lt;strong&gt;competent observer&lt;/strong&gt; in the aircraft adequately supplements the vision of the safety pilot …&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Is the “competent observer” a passenger or a required crewmember?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-08T18:23:21.650" Title="Is the “competent observer” a required crewmember?" Tags="&lt;faa-regulations&gt;&lt;safety-pilot&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26713" PostTypeId="2" ParentId="23058" CreationDate="2016-04-06T19:17:37.160" Score="3" Body="&lt;p&gt;The FAA interprets a limitation to its authority (which is derived from FAR 25.1309 for transport aircraft, for example): It is not supposed to say anything is &lt;strong&gt;required&lt;/strong&gt; to demonstrate compliance (for a module of software or a system of hardware) and be approved in the context of a certified aircraft. It can (and does) specify certain steps which constitute acceptable means of compliance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The documents in the &quot;chain of authority&quot;, not only DO-178C and DO-254, but also AC 20-152, are always careful to say that alternative means of compliance may be acceptable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The practical matter, however, is that if DO-178C is even plausibly appropriate for a software module, and if hardware being developed is at all within the ballpark of DO-254, the DER is likely to insist that those standards be followed.  And the FAA is certainly comfortable with that stance.  So although these documents are not normative, they are as important as if they were normative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the standards did include examples of alternative means of compliance, one of two things would happen.  Either these examples would be taken in the same semi-normative light that the rest of the standard is taken, in which case approval (where appropriate) based on some &lt;em&gt;other&lt;/em&gt; means of compliance would be that much less likely to be accepted, or the existence of the examples would overly encourage developers to fight for acceptance of their own means of compliance, in cases where DO-178C is perfectly applicable.  The latter would surely generate &quot;more heat than light.&quot;&lt;/p&gt;&#xA;" OwnerUserId="12120" LastActivityDate="2016-04-06T19:17:37.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26714" PostTypeId="2" ParentId="26712" CreationDate="2016-04-06T19:56:47.153" Score="1" Body="&lt;p&gt;No, it does not need to be a crew member.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the safety pilot has adequate vision forward and to each side, then no one else is required. Only in a case when there is some hinderance or obstacle in the field of view for the safety pilot, and a competent observer's view is not hindered by that obstacle, then they can be used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A competent observer is only an observer who is competent in observing. Logically, a crew member is always the first and preferred choice than curious or grumpy passengers. I did not find any details on the qualifications of a competent observer in the CFR.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-04-06T19:56:47.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26715" PostTypeId="2" ParentId="8145" CreationDate="2016-04-06T21:01:05.410" Score="1" Body="&lt;p&gt;The data you want is here: &lt;a href=&quot;http://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=236&amp;amp;DB_Short_Name=On-Time&quot; rel=&quot;nofollow&quot;&gt;http://www.transtats.bts.gov/DL_SelectFields.asp?Table_ID=236&amp;amp;DB_Short_Name=On-Time&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Select pre-zipped file to get all fields. You have to download it one month at a time.&lt;/p&gt;&#xA;" OwnerUserId="14362" LastActivityDate="2016-04-06T21:01:05.410" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26716" PostTypeId="2" ParentId="26709" CreationDate="2016-04-06T21:29:22.193" Score="0" Body="&lt;p&gt;&quot;Bypass&quot; in this context is how much air transits the actual fan stage and is used to directly generate thrust, vs. how much air transits the fan stage and moves into the compressor stage to be burned in the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low-bypass turbofans don't use a lot of air for thrust; most of the air that transits the fan stage is routed into the engine, compressed, combusted, and exhausted like a standard turbojet.  High-bypass turbofans route more air outside the combustion core, so the spinning fan generates most of the thrust (rather than the actual engine).  In this case, the turbojet core of the engine is used (mostly) to generate engine rotation, and the fans generate most of the thrust.&lt;/p&gt;&#xA;" OwnerUserId="14363" LastActivityDate="2016-04-06T21:29:22.193" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26717" PostTypeId="2" ParentId="26697" CreationDate="2016-04-06T21:51:25.923" Score="6" Body="&lt;p&gt;The chord length is a minor influence. The main driver for separation is the local pressure gradient.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Make sure to read the first three paragraphs of &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;this answer&lt;/a&gt; if you are unsure how the pressure gradient drives separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chord length only comes into play via the local Reynolds number. Higher Reynolds numbers mean steeper pressure gradients can be tolerated, but the effect is rather weak. It shows in the separation point which moves back slightly on the upper side of an airfoil near stall at the same angle of attack when the Reynolds number is increased.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-04-06T21:51:25.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26718" PostTypeId="2" ParentId="26712" CreationDate="2016-04-06T22:09:41.367" Score="6" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, the &quot;competent observer&quot; is a required crewmember in that situation, by definition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=17df02567828b3ce4bcb1d52e91d662f&amp;amp;mc=true&amp;amp;node=se14.1.1_11&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 1.1&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Crewmember&lt;/em&gt; means a person assigned to perform duty in an aircraft during flight time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Clearly, a &quot;competent observer&quot; operating as such under §91.109 (c)(2) is a person assigned to perform a duty in an aircraft during flight time; such an observer is therefore a crewmember. The operator is &lt;em&gt;required&lt;/em&gt; to operate the aircraft with that observer performing their observation duties, and that person is therefore a &lt;em&gt;required&lt;/em&gt; crewmember.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are no other requirements as to who this person may or may not be other than the qualifying term &quot;competent&quot;. The aircraft operator bears the burden of determining the observer's competency. One might argue that a certified pilot would be a competent observer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An implied question here might be, &lt;em&gt;is this competent observer a required crewmember that is able to log time for the performance of their duties&lt;/em&gt;? To this I would say, no, there is no provision in 14 CFR 61 for the logging of flight time for a person designated as an &quot;observer&quot;, competent or otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt; to further explain the above paragraph in consideration of discussion in the comments: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=6cf53aadcf7aef8afc22b537d49a8d4f&amp;amp;mc=true&amp;amp;node=se14.2.61_151&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;14 CFR 61.51&lt;/a&gt; allows &lt;em&gt;pilots&lt;/em&gt; to log PIC and SIC time for flight in, among other conditions, &quot;aircraft for which more than one pilot is required under the [...] regulations under which the flight is conducted&quot;. The &quot;qualified observer&quot; is indeed &lt;em&gt;required&lt;/em&gt; in the situation in question, but &lt;em&gt;need not&lt;/em&gt; be a pilot, and—unless otherwise qualified—&lt;em&gt;is not&lt;/em&gt; acting as one of the required pilots in an &quot;aircraft for which more than one pilot is required under the [...] regulations under which the flight is conducted&quot;. Obviously, if the person fulfilling the duties of a &quot;competent observer&quot; is otherwise &lt;em&gt;also&lt;/em&gt; a required pilot, then the pilot may log the flight time as the required &lt;em&gt;pilot&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-04-08T18:23:21.650" LastActivityDate="2016-04-08T18:23:21.650" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26720" PostTypeId="1" CreationDate="2016-04-07T05:44:30.783" Score="4" ViewCount="1236" Body="&lt;p&gt;Where can it possible to find pictures or drawings of &quot;endplate&quot;? (for &quot;winglet&quot; is much easier, but not endplate)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm asking what's written above, after I read the following text from Raymer and I need a better comprehension of it.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The wing aspect ratio &quot;$A$&quot; is the geometric aspect ratio of the&#xA;  complete reference planform. the effective aspect ratio will be&#xA;  increased by wing endplates or winglets&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Endplate: $A_{effective} = A(1+1.9\frac{h}{b})$ - (12.10)   where $h$ = endplate height&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Winglet: $A_{effective} = \approx 1.2A$  -     (12.11)&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;These effective aspect ratios should also be used in the induced drag&#xA;  calculations below. note that Eq. (12.11) for winglets is a crude&#xA;  approximation based upon limited data for wings of moderate aspect&#xA;  ratio&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;......................&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The extra drag due to non-elliptical lift distribution and the flow&#xA;  separation can be accounted for using e, the &quot;Oswald span efficiency&#xA;  factor&quot;. This effectively reduces the aspect ratio, producing the&#xA;  following equation for $K$&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;$K=\frac{1}{πAe}$ (12.48) &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;If the wing has end-plates or winglets, the effective aspect ratio&#xA;  from Eq. (12.10) or (12.11) should be used in Eq. (12.48)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Source: Daniel P. Raymer &quot;Aircraft design . A conceptual approach&quot; , Chapter 12 Aerodynamics)&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="13498" LastEditDate="2016-04-08T13:21:15.363" LastActivityDate="2020-02-20T00:34:10.790" Title="Where can I find pictures of &quot;endplate&quot;?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26723" PostTypeId="2" ParentId="26703" CreationDate="2016-04-07T08:38:30.503" Score="0" Body="&lt;p&gt;As soon as there is a positive rate of climb, the gear is retracted because it is a large contributor to &lt;em&gt;drag&lt;/em&gt; on the aircraft, effectively reducing its climb performance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a passenger you can feel this on some aircraft when the gear is deployed as you can feel the drag on the aircraft (and depending on where you are sitting, you may be able to hear the gear deploying).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to its large effect on the performance of the aircraft, in some aircraft the gear is also used as an impromptu air brake to reduce the speed of the aircraft - although in most modern aircraft, this function is taken care of by the air brake/spoilers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Gear is retracted manually, usually by the pilot observing, and not by the pilot flying (PF). Usually the pilot observing will say &quot;positive rate, gear up&quot; and then move the lever to retract the gear - this is what you are observing in those videos.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-04-07T08:38:30.503" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26724" PostTypeId="1" CreationDate="2016-04-07T09:29:00.450" Score="0" ViewCount="58" Body="&lt;p&gt;I'm sure that all the technological advancements in various field are enabling us to create or develop stuffs which were unthinkable even few decade ago. My question is what is the current R&amp;amp;D stage in self flying commercial aircraft or any project in the pipeline ? Also, who is leading this concept?&lt;/p&gt;&#xA;" OwnerUserId="14371" LastEditorUserId="62" LastEditDate="2016-04-07T11:56:04.460" LastActivityDate="2016-04-07T11:56:04.460" Title="Self-flying commercial aircraft!" Tags="&lt;aircraft-design&gt;&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-04-07T11:32:15.653" ContentLicense="CC BY-SA 3.0" />
  <row Id="26725" PostTypeId="2" ParentId="25172" CreationDate="2016-04-07T09:50:42.160" Score="2" Body="&lt;p&gt;The traffic pattern altitude (and the pattern turn direction) is set by the airport owner in coordination with the FAA. &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC90-66A.pdf&quot; rel=&quot;nofollow&quot;&gt;Refer to section 8.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport traffic patterns are often 1000 ft. AGL today. In recent past, the typical altitude above ground level was 800 ft. Flying Magazine, in a September 1958 article states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Under VFR conditions proper entry into the zone is sadly neglected. Before you enter the control zone you should be at the Pattern Altitude which is more or less standard rule at every airport in the country--800 to 1,000 feet for light aircraft, 1,200 to 1,500 for heavy or fast aircraft. This provides you with altitude, yet gives plenty of room to make your turns. Letting down in traffic makes you vulnerable and blind, at the same time increasing the odds of hitting someone you will never see&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Experts and non-experts seem to agree an altitude increase would be beneficial:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Better noise abatement near the airport environment&lt;/li&gt;&#xA;&lt;li&gt;Increasing tower heights&lt;/li&gt;&#xA;&lt;li&gt;1000 is easier to remember than 800&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Fun facts:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Tangier island/KTGI airport elevation is 6 ft mean sea level. The traffic pattern altitude is 605 ft.&lt;/li&gt;&#xA;&lt;li&gt;Truckee/KTRK is 5901 ft. MSL with an 1100 ft. TPA.&lt;/li&gt;&#xA;&lt;li&gt;Sedona/KSEZ is 4830 ft. MSL. The TPA is 1173 ft.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Pilots flying into Sedona must be precise, haha!&lt;/p&gt;&#xA;" OwnerUserId="12288" LastEditorUserId="12288" LastEditDate="2016-04-09T00:27:46.177" LastActivityDate="2016-04-09T00:27:46.177" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26727" PostTypeId="1" CreationDate="2016-04-07T11:37:40.787" Score="7" ViewCount="11336" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Does a pilot need to communicate with ATC while flying VFR (during departure, flight or departure) or does it depend on type of flight (like private, commercial, etc.)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Or is it required for pilot to inform ATC only during arrival and departure for runway clearance and altitudes?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If a pilot does not remain in contact with ATC during the flight, how does ATC know what pilot's intentions are?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="2143" LastEditDate="2016-08-21T12:04:35.773" LastActivityDate="2019-01-12T16:46:46.257" Title="Is it required for pilots to contact ATC while flying VFR?" Tags="&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="1" ClosedDate="2019-01-13T06:18:26.520" ContentLicense="CC BY-SA 3.0" />
  <row Id="26728" PostTypeId="1" CreationDate="2016-04-07T11:45:18.733" Score="23" ViewCount="5783" Body="&lt;p&gt;Usually we read, on reports, aircraft reporting urgency or emergency during the flight, while airborne. But, is it correct to use these &quot;words&quot; on ground?&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="487" LastEditDate="2016-04-07T17:57:17.363" LastActivityDate="2016-04-07T20:13:12.510" Title="Can we use MAYDAY or PAN PAN on ground?" Tags="&lt;emergency&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26729" PostTypeId="2" ParentId="26727" CreationDate="2016-04-07T11:49:58.307" Score="2" Body="&lt;p&gt;Note: This answer is specifically about procedures in the USA; it does not apply to the rest of the world, although most countries are very similar.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It depends &quot;where&quot; you are flying resp. in &lt;em&gt;which&lt;/em&gt; airspace.&#xA;The airspace is divided into types, according to the picture attached, and is an international classification. It is then up to the countries to split their airspace (including the one in the vicinity of the airfields) into the shown ones (some use just two, some use more).&#xA;On specific charts, you can see if it is necessary or not.&#xA;Summarizing, in controlled airspace (so if the airfield lies inside of an airspace class E or higher) it is mandatory.&#xA;If the airspace around an airfield is of class F (missing in the chart) or G, it is not. This is quite often the case for smaller airfields.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Q2IeP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Q2IeP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="14957" LastEditDate="2016-08-22T19:18:52.573" LastActivityDate="2016-08-22T19:18:52.573" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26730" PostTypeId="2" ParentId="26720" CreationDate="2016-04-07T11:53:13.100" Score="2" Body="&lt;p&gt;I seem to remember that wing end plates were sometimes used on Short Take Off and Landing(STOL) aircraft in the 1960's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found a few photos while doing an internet search but they seem to be much more prevalent on race car wings these days. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QrYAy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QrYAy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/II73j.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/II73j.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ptDqg.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ptDqg.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Dk9v.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Dk9v.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5NgS4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5NgS4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an explanation of why end plates are used on race cars: &lt;a href=&quot;http://thewptformula.com/2013/08/13/analysis-rear-wing-endplates/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Analysis: Rear Wing Endplates&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The endplate has two functions, the primary reason for their shape is&#xA;  to control the wingtip vortices at the trailing edge of the wing as&#xA;  this reduces drag and also lift. The second reason is that they&#xA;  control how the airflow makes its way over, under or around the&#xA;  aerofoil device that is creating the downforce on the car, resulting&#xA;  in better airflow management and maximising the performance of the&#xA;  component.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TvR6o.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TvR6o.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-07T17:25:23.577" LastActivityDate="2016-04-07T17:25:23.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26731" PostTypeId="1" AcceptedAnswerId="26735" CreationDate="2016-04-07T12:01:48.183" Score="24" ViewCount="9688" Body="&lt;p&gt;There have been many accidents involving metal fatigue. How do the engineers, maintenance team, etc. know if an aircraft has metal fatigue? What is done to &quot;minimize&quot; metal fatigue or repair it?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2019-02-04T06:21:15.557" LastActivityDate="2019-02-25T13:44:48.663" Title="How is metal fatigue detected in an aircraft?" Tags="&lt;aircraft-maintenance&gt;&lt;fatigue&gt;" AnswerCount="4" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26732" PostTypeId="2" ParentId="26728" CreationDate="2016-04-07T12:01:56.557" Score="11" Body="&lt;p&gt;Absolutely they are correct to use on the ground if the situation warrants. They are used to express an emergency or urgency, and those can happen on the ground as well as the air. Those conditions are roughly the same: passenger illness requiring medical assistance, an engine fire, unlawful interference, etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you make the call you would report your position as being on the ground, and where you are. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-04-07T12:01:56.557" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26733" PostTypeId="2" ParentId="26728" CreationDate="2016-04-07T12:05:53.230" Score="22" Body="&lt;p&gt;Yes, it is correct to use MAYDAY or PAN PAN PAN on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In recurrent training we are often reminded that in the case of a rejected takeoff in a foreign country it is important to use MAYDAY or PAN PAN PAN on the ground to avoid any confusion due to language difficulties. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's probably a good idea at any airport as a disabled aircraft on a busy runway could be a major hazard to other aircraft landing and taking off. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-07T12:05:53.230" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26734" PostTypeId="2" ParentId="26731" CreationDate="2016-04-07T12:28:31.580" Score="3" Body="&lt;p&gt;Some metal fatigue can be spotted visually as an visible crack or as a collection of tiny cracks that can give the metal a 'frosty' look but most is done via non-visual non destructive testing techniques such as radiography (basically X-raying) or Ultrasonic testing to search for microfractures before they reach the problem stage. Visual checks are no use for platform critical damage as by the time you see it it is well into the failed zone which is why NDT techniques are used to detect an impending failure well before it causes a problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other techniques such as Dye Penetrant tests where a dye in a carrier fluid is painted into the surface and then wiped off. The fluid is light enough to penetrate and 'wick' into any fine cracks and will highlight cracks that are invisible to the eye. The dye is often fluorescent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for what can be done it very much depends in the extent and location of the cracking. Extensive damage and/or damage to critical area will be repaired by replacement, minor damage can be gouged out and welded up.&#xA;The best method of minimising fatigue it to prevent it and so most manufacturers will feed back fatiguing data from surveys to the design sections who will design out the weak point if one exists. Real life data trumps even the most extensive FEA predictions.&lt;/p&gt;&#xA;" OwnerUserId="14127" LastActivityDate="2016-04-07T12:28:31.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26735" PostTypeId="2" ParentId="26731" CreationDate="2016-04-07T12:31:39.937" Score="25" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;How do the engineers, maintenance team, etc know if an aircraft has metal fatigue?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;First of all, is not an &quot;aircraft&quot; that has fatigue, but a component.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the naked eye, there is no way to detect metal fatigue until it starts being too late: you can only see cracks that are already forming and/or propagating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are tools available to allow for early detection, my bachelor's thesis was about one of these: the &lt;a href=&quot;https://en.wikipedia.org/wiki/Photoelasticity&quot;&gt;photoelasticity&lt;/a&gt; of certain materials is used. A light coat of one such material is applied on the new component and the photoelastic properties and exams done during the lifetime of the component tell the maintenance people what is the current status of the inner layers of the piece.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another method uses electric resistance, as metal fatigue, by cracking the metal, increases the resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the scenario, X-rays could also be used.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What do they do to &quot;minimize&quot; metal fatigue or repair it?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You cannot minimize fatigue, once it starts setting in, it is an irreversible process. You can delay the likely catastrophic failure by applying strengthening elements around the affected one, but the safest course of action is to replace the component and recycle the old one.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-04-07T12:31:39.937" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26736" PostTypeId="2" ParentId="26731" CreationDate="2016-04-07T12:34:42.757" Score="1" Body="&lt;p&gt;The pilot listens and notify the technicians that the plane is giving out strange noises.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And now seriously: For each plane type there are cards which parts need to be replaced or inspected after certain flight hours, start count or time. Together with required quality control at production and maintenance it should prevent metal fatigue incidents as much as possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And for the rest - @AndyW already mentioned techniques used during the inspections&lt;/p&gt;&#xA;" OwnerUserId="14373" LastActivityDate="2016-04-07T12:34:42.757" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26737" PostTypeId="2" ParentId="26731" CreationDate="2016-04-07T12:39:56.627" Score="14" Body="&lt;p&gt;Engineers have a variety of ways to detect metal fatigue in aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Visual inspection: sometimes cracks are visible to the naked eye, or can be seen under magnification&lt;/li&gt;&#xA;&lt;li&gt;Auditory inspection: sometimes a thump sounding wrong can give a clue that there's an issue. It's not a primary means of checking for fatigue, but something that may clue in an astute engineer that something needs to be looked into&lt;/li&gt;&#xA;&lt;li&gt;Ultrasound: Ultrasound uses very high pitched sound waves to image materials and can be used to find cracks inside materials&lt;/li&gt;&#xA;&lt;li&gt;Radiology: xrays and other types of radio imaging can be used to find sub-surface cracks&lt;/li&gt;&#xA;&lt;li&gt;Visible dyes: flourescent dyes in penetrating oils show up cracks which make it to the surface&lt;/li&gt;&#xA;&lt;li&gt;Magnetic powders: these only work on iron-based parts which are rare on an aircraft but are used&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Here's a &lt;a href=&quot;http://www.aviationpros.com/article/11281754/nondestructive-testing-then-now-and-in-the-future&quot;&gt;good article&lt;/a&gt; that goes into some details on non-destructive fatigue testing. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-04-07T12:39:56.627" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26739" PostTypeId="2" ParentId="908" CreationDate="2016-04-07T14:11:01.663" Score="6" Body="&lt;p&gt;It might be worth remembering that both these terms have a nautical origin. On the sea, &lt;strong&gt;pan-pan-pan&lt;/strong&gt; (from the french &lt;em&gt;en panne&lt;/em&gt;, meaning &lt;em&gt;broken down&lt;/em&gt;) usually meant that your engine was out and that you were drifting. You were not in immediate danger but obviously, you could soon be hitting rocks or drifting into the path of other vessels with no way to alter your heading. &lt;strong&gt;May-day&lt;/strong&gt; (from the french &lt;em&gt;m'aidez&lt;/em&gt; meaning &lt;em&gt;help me&lt;/em&gt;) usually meant that you were sinking.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These don't translate to aircraft so well since planes can't generally drift along aimlessly for very long. So probably the category for &lt;em&gt;pan-pan&lt;/em&gt; is rather narrow.&lt;/p&gt;&#xA;" OwnerUserId="9189" LastActivityDate="2016-04-07T14:11:01.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26740" PostTypeId="1" CreationDate="2016-04-07T14:17:18.590" Score="6" ViewCount="1425" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/908/when-should-the-term-pan-pan-be-used-instead-of-mayday&quot;&gt;This question&lt;/a&gt; deals with the pilot procedures for declaring an emergency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder how ATC in the US handles different kinds of emergency or quasi-emergency situations, such as:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;MAYDAY&lt;/li&gt;&#xA;&lt;li&gt;PAN PAN&lt;/li&gt;&#xA;&lt;li&gt;Minimum Fuel&lt;/li&gt;&#xA;&lt;li&gt;Medivac&lt;/li&gt;&#xA;&lt;li&gt;etc&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Are there multiple levels of priority handling inside ATC, and how do they communicate priority handling from controller to controller?&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-07-09T20:44:14.730" Title="How does ATC handle different kinds of emergencies?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;emergency&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26741" PostTypeId="2" ParentId="20838" CreationDate="2016-04-07T14:30:45.240" Score="8" Body="&lt;p&gt;As per &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap2_section_1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7110.65 &lt;strong&gt;ATC&lt;/strong&gt;&lt;/a&gt;, Section 2-1-16 SURFACE AREAS, when you are in contact with ATC, you do not need to specifically ask for authorization to enter a towered service area:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; Coordinate with the appropriate control tower for transit authorization when you are providing radar traffic advisory service to&#xA;an aircraft that will enter another facility's airspace.&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;NOTE-&lt;/strong&gt;&lt;/em&gt;&lt;br /&gt;&#xA;&lt;em&gt;The pilot is not expected to obtain his/her own authorization through each area when in contact with a radar facility.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="14897" LastEditDate="2021-04-12T23:39:36.677" LastActivityDate="2021-04-12T23:39:36.677" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="26742" PostTypeId="2" ParentId="26702" CreationDate="2016-04-07T15:55:19.193" Score="6" Body="&lt;p&gt;The air doesn't notice or care that we humans use so many different names for those wingtip extensions. They all help to keep the pressure difference up between both sides of the tip and add some friction drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since giving basically the same thing such a variety of names is a pettifoggery and there is no standardization for naming them, it is hard to give a clear, distinguishing feature. If I now say that endplates extend to both sides of the wing and are smaller, while winglets point up only and are larger, I am sure that somebody will rightfully point out an exception to this rule. Just look at the latest monstrosity Boeing added to their new &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_Next_Generation&quot; rel=&quot;nofollow noreferrer&quot;&gt;737NG&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0MGzG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0MGzG.jpg&quot; alt=&quot;Boeing scimitar winglets&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing scimitar winglets (picture &lt;a href=&quot;http://static4.businessinsider.com/image/51e713a46bb3f7522200001c-1200-/hop_6091-1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the term endplate is used, the transition between wing and extension is sudden and sharp, while winglets tend to have a smooth, rounded transition. Maybe this would be a better guide, but also here exceptions can be found.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1467" LastEditDate="2016-04-08T07:21:21.470" LastActivityDate="2016-04-08T07:21:21.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26743" PostTypeId="1" AcceptedAnswerId="26746" CreationDate="2016-04-07T16:12:43.303" Score="4" ViewCount="1367" Body="&lt;p&gt;I'm tasked with developing part of a cross country flight plan to cap off my ground school class. Among my group, I am handling the radio communications and regulations. However, I was not provided further details, and came here to gain a greater understanding of what I need to accomplish. Specifically, the trip is to fly from Aspen, fly by Capital Peak for the view, and then land in DIA (KBDU-KASE-KDEN). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far a radio communications go, I imagine I need the frequency of each of the listed airports, but is there anything else I need to consider? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Further Information:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm flying N370SP, a Cessna 172S Skyhawk SP. I pick up friends (190, #320) and luggage (35, #60).&lt;/p&gt;&#xA;" OwnerUserId="14374" LastEditorUserId="14374" LastEditDate="2016-04-07T16:23:46.317" LastActivityDate="2016-04-08T17:25:53.840" Title="Cross Country flight: what do I have to consider concerning radio communications?" Tags="&lt;flight-planning&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26744" PostTypeId="2" ParentId="26743" CreationDate="2016-04-07T16:32:42.000" Score="4" Body="&lt;p&gt;There are three categories of radio communication to deal for each leg of a flight:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;arrival and departure airport: tower/CTAF, ATIS/ASOS/AWOS, Ground/Clearance Delivery&lt;/li&gt;&#xA;&lt;li&gt;En route ATC: arrival/departure, center&lt;/li&gt;&#xA;&lt;li&gt;En route weather and information: Flight Service, Flightwatch, HIWAS, en-route ATIS&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You have to decide which of these services you will interact with, and know where to find the frequencies (almost always a chart or the A/FD) and how to contact each of them.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-07T16:32:42.000" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26745" PostTypeId="1" AcceptedAnswerId="26748" CreationDate="2016-04-07T18:50:11.227" Score="8" ViewCount="3575" Body="&lt;p&gt;When using ADS-B are squawk codes still necessary or does the unit provide a discrete code (like a tail number or something) that is recognized by ATC? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-07-09T20:37:49.780" Title="Are squawk codes used with ADS-B?" Tags="&lt;air-traffic-control&gt;&lt;ads-b&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26746" PostTypeId="2" ParentId="26743" CreationDate="2016-04-07T18:58:04.760" Score="3" Body="&lt;p&gt;A common way to approach this is to walk through the flight and write down each frequency you'll need in order. Your route is a bit unclear (are you departing Aspen or landing there?) but let's say it's KBDU-KASE-KDEN and it's a VFR flight. And I'm assuming you're only asking about comms, not nav.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You think through what you're doing at each point and then write down the station, frequency and what you plan to say, request or listen for, as the case may be. For example, you're departing &lt;a href=&quot;http://airnav.com/airport/KBDU&quot; rel=&quot;nofollow&quot;&gt;KBDU&lt;/a&gt;; it's uncontrolled so you'll check the AWOS and then use the CTAF to announce your intentions as you taxi and depart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After that the route to KASE seems to be through uncontrolled airspace but you'll probably want to get the Empire and Copper Mtn AWOS along the way. And if you want flight following then you'll have to call Denver Center to get it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://airnav.com/airport/KASE&quot; rel=&quot;nofollow&quot;&gt;KASE&lt;/a&gt; is controlled, so you'll need to get their ATIS, then call the tower, and after landing you'll be handed off to Ground. Departing KASE, you'll get the ATIS, call Ground, then the Tower and after departure maybe Denver Center again for flight following.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And so on...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll end up with a frequency log like this:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;KBDU - AWOS - 118.825 - Get altimeter, wind, etc.  &lt;/li&gt;&#xA;&lt;li&gt;KBDU - CTAF - 122.725 - Announce taxi and departure &lt;/li&gt;&#xA;&lt;li&gt;Denver Ctr - 126.1 - Request flight following &lt;/li&gt;&#xA;&lt;li&gt;Empire AWOS - 134.325 - Get WX and compare to forecast; change flight plan if needed&lt;/li&gt;&#xA;&lt;li&gt;[...]&lt;/li&gt;&#xA;&lt;li&gt;KASE - ATIS - 120.4 - Get WX and runway in use &lt;/li&gt;&#xA;&lt;li&gt;KASE - Tower - 118.85 - Announce landing intentions (check two way comms before entering class D!)&lt;/li&gt;&#xA;&lt;li&gt;KASE - Ground -121.9 - Request taxi to FBO&lt;/li&gt;&#xA;&lt;li&gt;[Etc...]&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This can be a really useful planning exercise, especially in unfamiliar areas. If you're unsure of the phraseology or procedures for any item on the list then you can talk to your instructor about it, and listen to real comms on &lt;a href=&quot;http://www.liveatc.net/&quot; rel=&quot;nofollow&quot;&gt;LiveATC&lt;/a&gt;. &lt;a href=&quot;http://airnav.com/airport/KDEN&quot; rel=&quot;nofollow&quot;&gt;KDEN&lt;/a&gt; in particular would (will?) be busy, it's class B.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But remember that plans change. ATC may give you an unexpected frequency, or you may copy down a frequency incorrectly and then find no one is listening. Make sure that you update your log in flight as needed; don't fixate on it being 'correct' to the point where you ignore instructions or information to the contrary; and be able to look up frequencies quickly on your charts or flight software.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-04-08T13:29:30.290" LastActivityDate="2016-04-08T13:29:30.290" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26747" PostTypeId="2" ParentId="26695" CreationDate="2016-04-07T19:05:50.263" Score="4" Body="&lt;p&gt;The theoretical answer to your question is that you can always get an IFR clearance directly from ATC over the radio, and filing a flight plan in advance isn't required (but it is strongly advised to avoid delays).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reality, however, you should file in advance if at all possible. This is from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-1-8&lt;/a&gt; (my emphasis):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Instrument flight plans may be submitted to the nearest FSS or ATCT&#xA;  either in person or by telephone (or &lt;strong&gt;by radio if no other means are&#xA;  available&lt;/strong&gt;). Pilots should file IFR flight plans at least 30 minutes&#xA;  prior to estimated time of departure to preclude possible delay in&#xA;  receiving a departure clearance from ATC.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The IFR flight plan system is there for good reasons: it helps ATC manage busy airspace and it avoids the need for lengthy radio discussions. If you don't file a flight plan in advance then you'll probably annoy ATC and you may be delayed because they can't take your request directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pop-up clearances by definition don't have a full flight plan filed in advance, but they do have an &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;abbreviated IFR flight plan&lt;/em&gt;&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An authorization by ATC requiring pilots to submit only that&#xA;  information needed for the purpose of ATC. It includes only a small&#xA;  portion of the usual IFR flight plan information. In certain&#xA;  instances, this may be only aircraft identification, location, and&#xA;  pilot request. Other information may be requested if needed by ATC for&#xA;  separation/control purposes. It is frequently used by aircraft which&#xA;  are airborne and desire an instrument approach or by aircraft which&#xA;  are on the ground and desire a climb to VFR-on-top.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Weather isn't predictable and a VFR flight may have to become IFR for safety reasons, so there needs to be some flexibility for aircraft that are actually in the air. A pop-up clearance is just a different, simpler way of requesting an IFR clearance; once you have it, you're IFR and operating in exactly the same way that you would if you had filed in advance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Descending to VFR conditions is an interesting idea but ATC can't clear you to descend below the minimum IFR altitude for the area. You could request the lowest altitude ATC can give you, then cancel IFR if you break out. But descending without a specific altitude restriction seems very risky: the temptation would be to keep going lower to &quot;have a look&quot;, and that could end up as a &lt;a href=&quot;https://aviation.stackexchange.com/q/22052/62&quot;&gt;CFIT incident&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, at least in my experience the 30-minute 'rule' is really a guideline to avoid delays. I've never had an issue filing IFR and departing 15 minutes later, but then I'm usually flying between class C or D airports and the airspace isn't particularly busy. A class B airport is probably a different story.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-04-07T19:05:50.263" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26748" PostTypeId="2" ParentId="26745" CreationDate="2016-04-07T19:33:54.940" Score="6" Body="&lt;p&gt;Yes, squawk codes are still used and required with ADS-B.&lt;br&gt;&#xA;It's possible that in the future this may change, but because of the bifurcated implementation the FAA has chosen for ADS-B I don't think it's likely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ADS-B operates by giving &lt;em&gt;additional&lt;/em&gt; information beyond the Mode A (squawk) code - this is either encoded on the 1090MHz transponder frequency (Mode S &quot;Extended Squitter&quot; - what most of the world uses) or sent on a separate frequency (the 987MHz &quot;Universal Access Transceiver&quot; frequency, which is a US/FAA only thing mainly intended for light GA aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Mode S and Extended Squitter data includes things like the aircraft's unique Mode S address (a 24-bit number assigned to the aircraft by its national registry, in the US this is linked to the N number), and may also provide the tail number or flight number. The ATC radar system will accept and display this information for the controller.&lt;br&gt;&#xA;At the moment the Mode S/ES data is not used as a substitute for the Mode A transponder code, but because Mode S data is coming through the ATC secondary radar system it's all immediately available with the secondary radar return the same way a Mode A squawk code is, and it's possible that the FAA may use the Mode S ID in place of the Mode A squawk code for these aircraft in the future.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 987MHz UAT transmissions also include the Mode S address (because it's a useful unique identifier for a given aircraft) and flight ID/tail number can be sent as well. Information from UAT transmitters is received through separate ground stations and recombined with the radar return in the ATC radar back-end.&lt;br&gt;&#xA;There's some magic to that recombining which is out of my depth, but my limited understanding is that since the UAT data isn't directly correlated with a radar return squawk codes are part of how the two are matched up (the radar computer knows your N number by your discrete squawk code, the UAT ground station knows it from your Mode S ID - if they match and the position data is within reason the ADS-B information can be associated with your radar data block). &lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-04-07T19:33:54.940" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26751" PostTypeId="2" ParentId="26740" CreationDate="2016-04-07T21:03:36.830" Score="7" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order JO 7110.65W - ATC Procedures, Chapter 10&lt;/a&gt; outlines how ATC should handle procedures for emergency situations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the very first section though, it says: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;10-1-1(d)&lt;br/&gt;&#xA;  Because of the infinite variety of possible emergency situations, specific procedures cannot be prescribed. However, when you believe an emergency&#xA;  exists or is imminent, select and pursue a course of action which appears to be most appropriate under the circumstances and which most nearly conforms to the instructions in this manual.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, for Mayday and Pan-Pan, it says in 10-1-1(a):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A pilot who encounters a Distress condition should declare an emergency by beginning the initial communication with the word “Mayday,” preferably&#xA;  repeated three times. For an Urgency condition, the word “Pan-Pan” should be used in the same manner.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The use of Mayday and Pan-Pan declares an emergency, but doesn't tell ATC about the &lt;em&gt;nature&lt;/em&gt; of that emergency. Therefore just saying those words doesn't trigger any particular method for handling the emergency other than probably the controller offloading other traffic and giving you priority handling. It'll probably also trigger a clearing of the airspace around you, and if you are on final or near an airport, a ground hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For Medevac:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2-1-4(b) outlines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Provide priority to civilian air ambulance flights (call sign “MEDEVAC”). Use of the MEDEVAC call sign indicates that operational&#xA;  priority is requested. When verbally requested, provide priority to AIR EVAC, HOSP, and scheduled air carrier/air taxi flights. Assist the pilots of&#xA;  MEDEVAC, AIR EVAC, and HOSP aircraft to avoid areas of significant weather and turbulent conditions. When requested by a pilot, provide notifications to&#xA;  expedite ground handling of patients, vital organs, or urgently needed medical materials.&lt;br/&gt;&lt;br/&gt;&#xA;  &lt;em&gt;NOTE−&lt;br/&gt;&#xA;  It is recognized that heavy traffic flow may affect the controller’s ability to provide priority handling. However, without compromising safety, good judgment must be used in each situation to facilitate the most expeditious&#xA;  movement of a MEDEVAC aircraft.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;For Minimum Fuel&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2-1-8 Outlines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If an aircraft declares a state of “minimum fuel,” inform any facility to whom control jurisdiction is transferred of the minimum fuel problem and be alert&#xA;  for any occurrence which might delay the aircraft en route.&lt;br/&gt;&lt;br/&gt;&#xA;  &lt;em&gt;NOTE−&#xA;  Use of the term “minimum fuel” indicates recognition by a pilot that his/her fuel supply has reached a state where, upon reaching destination, he/she cannot accept any undue delay. &lt;strong&gt;This is not an emergency situation but merely an&#xA;  advisory that indicates an emergency situation is possible&lt;/strong&gt; should any undue delay occur. A minimum fuel advisory &lt;strong&gt;does not imply a need for traffic priority&lt;/strong&gt;. Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, the pilot should declare an emergency and report fuel remaining in minutes.&lt;/em&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Really you should read through the entire (long) document to see how ATC is supposed to behave for certain situations. Chapter 2, Section 1 has a lot of &quot;emergency&quot; situations, but most of it boils down to giving priority and assistance that the pilot asks for.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-07T21:17:32.483" LastActivityDate="2016-04-07T21:17:32.483" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26752" PostTypeId="2" ParentId="21953" CreationDate="2016-04-07T21:19:57.267" Score="1" Body="&lt;p&gt;Simon mentioned a great list of common checklists (of course, keep in mind there are lots of other checklists for emergency situations; fuel dump, engine out, engine fire, hydraulics, etc. etc.)- I would like to address one specific point in your question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I wanted to know the number of times a pilot &lt;strong&gt;has to refer&lt;/strong&gt; to his/her checklist&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't mean to be pedantic here, but checklists are always referred to (in other words, they are not memorized). Even the most experienced pilots go through the checklist &lt;em&gt;manually&lt;/em&gt;  - of course - it takes them quicker to go through each checklist due to their experience but they always refer to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have the most experience with the 737 and on this aircraft, typically the checklists are laminated and on some aircraft placed above the cockpit instrument cluster; in addition some checklists are actually written on the yoke itself:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ori7T.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ori7T.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(image from wikipedia entry on yoke)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The checklists are before takeoff / after takeoff / approach / landing. The little yellow bug (on the right) is to keep track of the items.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During one of my orientation sessions, the instructor reminded me to not do the checklist by memory, you must always refer to the written list.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He then mentioned &lt;em&gt;&quot;in the air force they make us memorize the checklists and do them by memory, but not on civilian aircraft&quot;&lt;/em&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-04-07T21:19:57.267" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26754" PostTypeId="1" AcceptedAnswerId="26807" CreationDate="2016-04-08T00:11:12.933" Score="10" ViewCount="352" Body="&lt;p&gt;Ok, before you say, &quot;Military Training Routes are used for... uhh... military training,&quot; let me elaborate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've read about how they work with ATC and speed restrictions etc. What I'm wondering is what they do on them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take, for instance, IR-504. It starts in the middle of nowhere about 20 miles south of the BUM vortac in western Missouri, almost 70 miles from the nearest Air Force Base. It takes numerous turns and meanders, seemingly randomly all over northeastern Kansas. It finally ends in an MOA in the middle of the state, but once again, not by a base or anything. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't see any rhyme or reason to the routing and can't imagine what it would be used to train for. It's not bombing practice; only a very small section is inside an MOA. It can't be terrain following exercises; its an IFR route and 3 digits means over 1500ft agl. Besides, what terrain could they be following? We're talking about central Kansas here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What in the world do they use these routes for?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="62" LastEditDate="2016-04-08T00:45:28.990" LastActivityDate="2016-04-13T07:29:08.787" Title="What are MTRs used for?" Tags="&lt;military&gt;&lt;flight-training&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26756" PostTypeId="1" AcceptedAnswerId="26818" CreationDate="2016-04-08T06:14:30.930" Score="9" ViewCount="834" Body="&lt;p&gt;I want to understand the theory behind supercritical airfoils and all the details about them. It would be nice if I could get a standard supercritical airfoil, its experimental Cl, Cd data in the transonic region and its verification from theory. I haven't been able to find anything concrete on the internet.&lt;/p&gt;&#xA;" OwnerUserId="3029" LastEditorUserId="1467" LastEditDate="2016-04-08T06:23:45.327" LastActivityDate="2019-11-05T15:10:17.613" Title="Which books should I study to understand more about Supercritical airfoils?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;drag&gt;&lt;airfoil&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26757" PostTypeId="1" AcceptedAnswerId="26758" CreationDate="2016-04-08T08:20:26.370" Score="11" ViewCount="2625" Body="&lt;p&gt;I didn’t notice any distance regulations or recommendations regarding how far away an alternate airport may be. However, it is reasonable that, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Too close: The weather between the two is likely to be similar. If you are unable to land in one, you are unlikely to land the other.&lt;/li&gt;&#xA;&lt;li&gt;Too far away: The fuel reserve is a concern, and we lose the purpose of the trip. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="2143" LastEditDate="2016-04-19T21:17:37.840" LastActivityDate="2018-12-29T13:31:52.280" Title="Are there any regulations about the distance between destination and alternate airports?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26758" PostTypeId="2" ParentId="26757" CreationDate="2016-04-08T08:38:15.723" Score="13" Body="&lt;p&gt;On an IFR flight plan, &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/135.223&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 135.233&lt;/a&gt; requires&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;h3&gt;§ 135.223 IFR: Alternate airport requirements.&lt;/h3&gt;&#xA;&lt;p&gt;&lt;strong&gt;(a)&lt;/strong&gt; Except as provided in paragraph (b) of this section, no person may operate an aircraft in IFR conditions unless it carries enough fuel (considering weather reports or forecasts or any combination of them) to—&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(1)&lt;/strong&gt; Complete the flight to the first airport of intended landing;&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(2)&lt;/strong&gt; Fly from that airport to the alternate airport; and&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(3)&lt;/strong&gt; Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Constraining from the other side, &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.169&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.169&lt;/a&gt; requires&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;(c) IFR alternate airport weather minima.&lt;/strong&gt; Unless otherwise authorized by the Administrator, no person may include an alternate airport in an IFR flight plan unless appropriate weather reports or weather forecasts, or a combination of them, indicate that, at the estimated time of arrival at the alternate airport, the ceiling and visibility at that airport will be at or above the following weather minima:&lt;/p&gt;&#xA;&lt;p&gt;    &lt;strong&gt;(1)&lt;/strong&gt; If an instrument approach procedure has been published inpart 97 of this chapter, or a special instrument approach procedure has been issued by the Administrator to the operator, for that airport, the following minima:&lt;/p&gt;&#xA;&lt;p&gt;        &lt;strong&gt;(i) For aircraft other than helicopters:&lt;/strong&gt; The alternate airport minima specified in that procedure, or if none are specified the following standard approach minima:&lt;/p&gt;&#xA;&lt;p&gt;            &lt;strong&gt;(A) For a precision approach procedure.&lt;/strong&gt; Ceiling 600 feet and visibility 2 statute miles.&lt;/p&gt;&#xA;&lt;p&gt;            &lt;strong&gt;(B) For a nonprecision approach procedure.&lt;/strong&gt; Ceiling 800 feet and visibility 2 statute miles.&lt;/p&gt;&#xA;&lt;p&gt;        &lt;strong&gt;(ii) For helicopters:&lt;/strong&gt; Ceiling 200 feet above the minimum for the approach to be flown, and visibility at least 1 statute mile but never less than the minimum visibility for the approach to be flown, and&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The maximum distance for an alternate airport is limited by your aircraft’s fuel range, but practicality (not losing the purpose of the trip) will tend to be more constraining than math. The minimum distance depends on the weather.&lt;/p&gt;&#xA;&lt;p&gt;Considering it from this perspective, given that the objective is safety, stipulating “at least X but no more than Y units of &lt;em&gt;distance&lt;/em&gt;” would be inappropriate for similar reasons as to why we tend to &lt;a href=&quot;http://aviation.stackexchange.com/q/8834/2143&quot;&gt;think of fuel in terms of time rather than length&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-12-29T13:31:52.280" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26759" PostTypeId="1" AcceptedAnswerId="26764" CreationDate="2016-04-08T11:09:09.707" Score="15" ViewCount="24027" Body="&lt;p&gt;I've been looking for this topic on the internet but I don't have enough concrete answers. Suppose we have a plane with dihedral and it has a suddenly swinging to the right (watching from the nose of the plane), so the right wing goes down. I'm trying to understand why the right wing generates more lift than the left wing when it has a sideslip. I have seen in some sites that the sideslip induces a flow from the tip to the root and this makes the right wing increase locally the angle of attack, hence the lift of this wing increases too. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, why the right wing increases the angle of attack? I think it couldn't be possible because the sideslip flow is in a different plane respect the mainstream.&lt;/p&gt;&#xA;" OwnerUserId="14384" LastEditorUserId="12220" LastEditDate="2016-04-08T14:59:38.043" LastActivityDate="2021-01-23T23:55:43.010" Title="How does the dihedral angle work?" Tags="&lt;aerodynamics&gt;&lt;wing&gt;" AnswerCount="5" CommentCount="3" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26762" PostTypeId="2" ParentId="26759" CreationDate="2016-04-08T14:40:38.130" Score="-5" Body="&lt;p&gt;This is a very exaggerated diagram of a fuselage with dihedral wings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the plane is flying normally (top), both wings produce the same lift vectors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the airplane is disturbed in the roll axis, and one wing goes higher than the other (bottom), the vertical lift vectors are different, with the &quot;down&quot; wing producing more vertical lift than the &quot;up&quot; wing. This increased vertical lift on the down wing and decreased vertical lift on the up wing, pushes the down wing up, and helps right the airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: everything in this diagram is schematic and is not meant to indicate any specific mathematical or physics laws or formulas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Kri9F.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Kri9F.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-04-08T14:45:53.117" LastActivityDate="2016-04-08T14:45:53.117" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26764" PostTypeId="2" ParentId="26759" CreationDate="2016-04-08T14:59:05.773" Score="13" Body="&lt;p&gt;Basically, dihedral effect is that during banking, the 'lower' wing will experience a higher angle of attack compared to the 'higher' wing, and a result, a greater lift. The resulting net force and moment reduces the banking angle, reducing stability.&lt;/p&gt;&#xA;&lt;p&gt;Consider a wing with a dihedral angle &lt;span class=&quot;math-container&quot;&gt;$\Gamma$&lt;/span&gt; with a forward airspeed of &lt;span class=&quot;math-container&quot;&gt;$u$&lt;/span&gt;. If the sideslip angle is &lt;span class=&quot;math-container&quot;&gt;$\beta$&lt;/span&gt;, the wind due to sideslip is &lt;span class=&quot;math-container&quot;&gt;$u \cdot \sin\beta$&lt;/span&gt;. From geometry, the normal velocity induced due to dihedral, &lt;span class=&quot;math-container&quot;&gt;$v_{n}$&lt;/span&gt; becomes &lt;span class=&quot;math-container&quot;&gt;$u \cdot \sin\beta \cdot \sin\Gamma$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bgvWo.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bgvWo.png&quot; alt=&quot;Dihedral angle&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=17&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwi2xM6dl__LAhUGto4KHTN5An4QFghxMBA&amp;amp;url=http%3A%2F%2Fwww.clarkson.edu%2F%7Epmarzocc%2FAE430%2FAE-430-7.pdf&amp;amp;usg=AFQjCNHmHTgbz_fVwZbPXQAxXKbhpBQAAw&amp;amp;bvm=bv.118817766,d.c2E&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stability and Control of Aerospace Vehicles&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Note: The notations are different in the figure; but the principle is the same.&lt;/p&gt;&#xA;&lt;p&gt;For our purposes, we can take the sideslip velocity (&lt;span class=&quot;math-container&quot;&gt;$u \cdot \sin\beta$&lt;/span&gt;) as &lt;span class=&quot;math-container&quot;&gt;$v_{y}$&lt;/span&gt;. Now, consider two sections from the wing - one each from the 'lower' and 'higher' sides. The induced velocity is of the same magnitude in both the sides, while the direction differs, as can be seen from the above figure.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/OULGV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OULGV.jpg&quot; alt=&quot;Dihedral angle&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://people.rit.edu/pnveme/EMEM682n/StaticStab/dihedral.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;people.rit.edu&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sqNiE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sqNiE.png&quot; alt=&quot;Wing section&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=17&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwi2xM6dl__LAhUGto4KHTN5An4QFghxMBA&amp;amp;url=http%3A%2F%2Fwww.clarkson.edu%2F%7Epmarzocc%2FAE430%2FAE-430-7.pdf&amp;amp;usg=AFQjCNHmHTgbz_fVwZbPXQAxXKbhpBQAAw&amp;amp;bvm=bv.118817766,d.c2E&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stability and Control of Aerospace Vehicles&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;For small angles, &lt;span class=&quot;math-container&quot;&gt;$v_{y}$&lt;/span&gt; is nearly equal to &lt;span class=&quot;math-container&quot;&gt;$u \beta$&lt;/span&gt;. The induced angle can be given as,&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\Delta \alpha = \frac{v_{n}}{u}$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;From the earlier relations, we have,&lt;/p&gt;&#xA;&lt;p&gt;&lt;span class=&quot;math-container&quot;&gt;$\Delta \alpha_{1} = \beta \cdot \sin\Gamma$&lt;/span&gt;, and &lt;span class=&quot;math-container&quot;&gt;$\Delta \alpha_{2} = -\beta \cdot \sin\Gamma$&lt;/span&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Because of these induced angles, the lift on the downgoing wing increases by &lt;span class=&quot;math-container&quot;&gt;$\Delta L$&lt;/span&gt;, while of the other one decreases by &lt;span class=&quot;math-container&quot;&gt;$\Delta L$&lt;/span&gt;. The net result is that the 'lower' wing experiences an increases lift, causing a rolling moment, which causes the banking angle to reduce.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w2968.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w2968.png&quot; alt=&quot;Dihedral&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=17&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwi2xM6dl__LAhUGto4KHTN5An4QFghxMBA&amp;amp;url=http%3A%2F%2Fwww.clarkson.edu%2F%7Epmarzocc%2FAE430%2FAE-430-7.pdf&amp;amp;usg=AFQjCNHmHTgbz_fVwZbPXQAxXKbhpBQAAw&amp;amp;bvm=bv.118817766,d.c2E&quot; rel=&quot;nofollow noreferrer&quot;&gt;Stability and Control of Aerospace Vehicles&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2021-01-23T23:55:43.010" LastActivityDate="2021-01-23T23:55:43.010" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26765" PostTypeId="1" AcceptedAnswerId="26768" CreationDate="2016-04-08T15:02:03.310" Score="5" ViewCount="5820" Body="&lt;p&gt;When reviewing notices to airmen (NOTAMs) for the KDNL airport today (08 April, 2016) there's a particular NOTAM that references an NTAP with a number. What's an NTAP? How does one go about looking one up?&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;!DNL 03/008 KDNL SVC SPECIAL EVENT MASTER'S GOLF TOURNAMENT SEE NTAP 1604031100-1604112359&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="5517" LastEditDate="2016-04-08T15:49:22.123" LastActivityDate="2016-04-08T19:36:32.030" Title="What is an NTAP when referenced in a NOTAM?" Tags="&lt;notam&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26766" PostTypeId="2" ParentId="26765" CreationDate="2016-04-08T15:10:27.170" Score="1" Body="&lt;p&gt;Simply enough, it is the &quot;Notices to Airmen publication&quot;, which has the full description of the NOTAM.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-08T15:10:27.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26767" PostTypeId="2" ParentId="26765" CreationDate="2016-04-08T15:11:36.260" Score="3" Body="&lt;p&gt;NTAP is the Notice to Airmen Publication. It is published every 28 days. The electronic version can be found in the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/notices/&quot; rel=&quot;nofollow&quot;&gt;faa site&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-08T15:11:36.260" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26768" PostTypeId="2" ParentId="26765" CreationDate="2016-04-08T16:30:40.690" Score="6" Body="&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/notices/&quot; rel=&quot;nofollow&quot;&gt;Notice to Airmen Publication&lt;/a&gt; is an FAA publication, currently available in PDF or print form, published every 28 days. The NTAP contains airway, airport, facility, procedural, general, and international NOTAMs. As voretaq7 notes, this includes long term NOTAMs that a flight service brief won't include if you don't ask. There is also a section with graphic notices, including general notices, special operations, airport and facility notices, and major sporting and entertainment events.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That last section is the one relevant for the NOTAM listed above. This lists information and procedures for any airports affected by special events, which is nice to have in one place rather than looking up long and complicated NOTAMs for each airport. For example, the Masters Golf Tournament referenced in the NOTAM above has a section in the NTAP, affecting airports AGS, AIK, DNL, and HQU. The information includes preferred IFR arrival routings, potential for holds and VFR arrival delays, departure procedures, preferred IFR departure routes, IFR overflights, and VFR arrivals/departures to/from DNL. There is also a special schedule for the tower at AGS, and a temporary tower at DNL. &lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-04-08T19:36:32.030" LastActivityDate="2016-04-08T19:36:32.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26770" PostTypeId="2" ParentId="26743" CreationDate="2016-04-08T17:15:40.607" Score="1" Body="&lt;p&gt;Normally what you do is group information for each leg of the flight. Each bundle of information should have everything you need, not just frequencies. So, you should have field elevation, runway length, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airports do not have just one frequency as your question seems to imply. Normally you will always have two frequencies at a minimum, which is CTAF and ground. For larger airports you will also have clearance delivery and tower. Make sure you label each frequency, that is critical. You do not want to be trying to get landing clearance from the guy that is driving the fuel truck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trickiest thing in radio work is a handover wherever you take off from one airport and enter the airspace of another. Since your radio may only have two frequencies you will have them set to tower and ground of the departure airport, but will need to immediately switch to ATC as soon as you take off while you are trying to do fifteen other things. So, if you have situation like this, you want to plan ahead carefully for how you handle it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is good idea to find out which airports have shared CTAF. In some cases you will hear traffic on CTAF which is actually pilots at &lt;em&gt;other airports&lt;/em&gt;, not the one you are at. They are supposed to announce the airport always, but do not always do so, also sometimes it is garbled. It can be very confusing if you hear some guy say &quot;on final for one six&quot; and you are looking around and wondering where the hell he is---he is at a &lt;em&gt;different&lt;/em&gt; airport. Don't make that mistake.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, practice your comm phrasing as much you can. You want to say exactly the right thing. It needs to be automatic. You don't want to be in a situation where you need to request something and can't remember how to phrase it. Practice your phraseology out loud until you have it down cold.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-04-08T17:25:53.840" LastActivityDate="2016-04-08T17:25:53.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26771" PostTypeId="1" AcceptedAnswerId="27520" CreationDate="2016-04-08T18:55:10.203" Score="10" ViewCount="406" Body="&lt;p&gt;I know that for ADS-B in the US to receive TIS-B information you need to be a participating aircraft (ie ADSB-Out).  My question is more specifically, if you are flying an aircraft with a 1090ES transponder and have a &lt;a href=&quot;http://stratux.me&quot; rel=&quot;nofollow noreferrer&quot;&gt;stratux&lt;/a&gt; or similar ADSB-In device for your phone or tablet, will the system create the traffic puck around your aircraft and send TIS-B information for you?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YfUlz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YfUlz.png&quot; alt=&quot;FAA Traffic Puck&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3931" LastEditorUserId="13197" LastEditDate="2016-04-16T21:14:33.883" LastActivityDate="2016-05-13T21:18:43.703" Title="What will create a &quot;traffic puck&quot; on the UAT band?" Tags="&lt;usa&gt;&lt;ads-b&gt;&lt;tis-b&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26772" PostTypeId="1" CreationDate="2016-04-08T19:06:08.420" Score="5" ViewCount="1553" Body="&lt;p&gt;When a passenger aircraft travels at higher altitudes will it be in constant touch with air traffic controller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the altitudes or flight levels assigned by ATC or does the pilot file them as part of flight plan?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While flying over regions with no radio communication, how does one ensure that there are no other aircraft nearby?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="13197" LastEditDate="2016-04-16T21:39:55.137" LastActivityDate="2016-04-16T21:39:55.137" Title="Will the ATC be in constant communication with aircraft?" Tags="&lt;air-traffic-control&gt;&lt;aircraft-systems&gt;&lt;altitude&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ClosedDate="2016-10-22T17:40:45.980" ContentLicense="CC BY-SA 3.0" />
  <row Id="26773" PostTypeId="2" ParentId="26772" CreationDate="2016-04-08T19:44:26.203" Score="1" Body="&lt;p&gt;At high altitudes one in never out of &lt;em&gt;radio&lt;/em&gt; range for ATC. The usual VHF airband frequencies only work within line-of-sight, but if you're too far away for that, one can switch to HF radio which follows the curvature of the Earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most parts of the oceans are outside &lt;em&gt;radar&lt;/em&gt; coverage, so the controller cannot see where you are. In these areas ATC depends on position reports from pilots for separating flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight plans contain a requested cruising altitude, which ATC will generally clear the flight for if possible, but when traffic requires it pilots have to take what ATC assigns.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2016-04-08T19:44:26.203" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26774" PostTypeId="2" ParentId="26759" CreationDate="2016-04-08T20:07:46.723" Score="11" Body="&lt;p&gt;The explanation lies in the fact that a rolled wing creates a oblique relative wind, and that a wing with a dihedral angle seen from an oblique direction is having a larger angle of attack on the side in this direction:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/91sNL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/91sNL.jpg&quot; alt=&quot;Looking at wings with a dihedral angle, from the wind direction&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Because of the dihedral angle, for the wind coming from an oblique direction on the right of the aircraft, the right wing shows a larger AoA. This is even more important for a larger dihedral angle.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Visual demonstration&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the image below:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;On the left side, there is an aircraft which is horizontal, flying level, and in a relative headwind. Obviously the action of the wind will be the same on both wings, whatever the dihedral angle, and the lift vector is oriented vertically (in blue).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;On the right side, the aircraft has been disturbed and for some reason is now rolled to the right without pilot action. Imagine the heading is still the same.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nVJry.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nVJry.png&quot; alt=&quot;Lift on horizontal and rolled wings&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key to see what will happen is to understand the right wing now develops more lift than the left wing, the difference being proportional to the dihedral angle. As soon as this is clear, we can anticipate the roll angle will be cancelled automatically, without pilot action.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's look at the rolled aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The lift vector, which is still normal to the wing, is no more vertical. From a mathematical point of view it &lt;a href=&quot;https://www.citycollegiate.com/vectorXc.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;can be split into two components&lt;/a&gt; along arbitrary directions. If we choose a resolution along the vertical and horizontal axes, we see the vertical component is now smaller (therefore the aircraft starts descending) and a horizontal component appeared in the process.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The horizontal component pulls the aircraft to the right side. As the heading is unchanged, the aircraft is not in a turn, and no centrifugal force opposes this horizontal component of the lift, therefore the aircraft starts side-slipping and the relative wind is no more a headwind, there is some crosswind from the right side.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Angle of attack seen from the relative wind standpoint: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;When the aircraft was flying in a headwind, the angle of attack was the same for both wings.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;With the crosswind component, the angle of attack of the right wing is higher than the angle of attack of the left wing. The difference is small when the dihedral angle is small, and increases with its value. To make this apparent, I added wings with higher dihedral angles to the aircraft:&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/91sNL.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/91sNL.jpg&quot; alt=&quot;Looking at wings with a dihedral angle, from the wind direction&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: The difference appears only when the wind is off axis. This means the dihedral effect on the angle of attack exists only when there is a sideslip.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course because the angle of attack is larger on the right, a recovery moment starts developing and counteracts the initial roll. The aircraft returns to the horizontal after some damped oscillations around the longitudinal axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lateral stability is of prime importance for general and commercial aviation aircraft. The dihedral angle is the most simple mean to obtain this stability, there are others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Stability from swept wing, due to spanwise flow&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is generated taking into account the airflow parallel to the chord which is accelerated. Air moved in a perpendicular direction is not accelerated and doesn't create any lift, see left image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MECEl.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MECEl.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By principle, a swept wing decreases the amount of lift created, this is compensated by other benefits that make it useful anyway).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the swept wing receives wind from an oblique direction, like during a sideslip, the available air energy will not be lost in the same proportion for each wing (see image on the right, above).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The chord of the right wing is better oriented in the airflow coming from the right, and a larger ratio of air generates lift compared to when the airflow comes frontally. This is the contrary for the left wing. This effect also contributes to lateral stability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Preventing spiral&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dihedral angle participates to the roll stability, along with other factors. The area where the dihedral plays a critical role is the stabilization of the &lt;em&gt;spiral mode&lt;/em&gt; (or spiral divergence).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The spiral mode, like the Dutch roll and the phugoid, is an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_dynamic_modes&quot; rel=&quot;nofollow noreferrer&quot;&gt;oscillatory mode&lt;/a&gt; that can either self-decay with time (stable) or constantly increase (unstable). The unstable spiral mode happens this way:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;(1) The disturbance creates a small roll moment and sideslip to the right.&lt;/li&gt;&#xA;&lt;li&gt;(2) The sideslip creates a crosswind component from the right.&lt;/li&gt;&#xA;&lt;li&gt;(3) The vertical stabilizer AoA increases and creates lift to the left.&#xA;&lt;BR&gt;&lt;BR&gt;&lt;a href=&quot;https://i.stack.imgur.com/dP7ng.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dP7ng.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;&lt;/li&gt;&#xA;&lt;li&gt;(4) Lift creates a yaw moment and turns the nose to the right.&lt;/li&gt;&#xA;&lt;li&gt;(1) The yaw moment increases the roll moment and the sideslip to the right (a new cycle has begun).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If this effect is not detected and corrected, which can easily happen in IMC when the natural horizon is not visible, the aircraft continues to sideslip and yaw, while the vertical component of the lift decreases due to the roll, creating a dangerous spiral downwards which can lead to structural damages or ground collision.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cycle is the result of all dynamic forces in action on the aircraft, in particular the lift on each wing and the position of the center of pressure. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The use of a dihedral wings affects the forces and their relative timing, and transforms an unstable spiral mode into a stable one. This is facilitated by also using a smaller vertical stabilizer and rudder, which in turn can create an unstable &lt;a href=&quot;https://en.wikipedia.org/wiki/Dutch_roll&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dutch roll&lt;/a&gt;, or a shorter cabin.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Thanks to &lt;a href=&quot;http://tf3dm.com/user/ahmetsalih&quot; rel=&quot;nofollow noreferrer&quot;&gt;ahmetsalih&lt;/a&gt; for the Learjet 3D model available at &lt;a href=&quot;http://tf3dm.com/3d-model/learjet-25-atlasjet-42833.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;TF3DM&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-28T17:27:41.627" LastActivityDate="2019-11-28T17:27:41.627" CommentCount="18" ContentLicense="CC BY-SA 4.0" />
  <row Id="26775" PostTypeId="2" ParentId="26772" CreationDate="2016-04-08T21:05:36.683" Score="4" Body="&lt;p&gt;Generally speaking airliners are always able to be in contact with ATC, either by VHF (regular radio), HF (usable over longer distances, e.g. on oceanic crossings), or satellite communication (possibly relayed through their company dispatch). It is also possible for one aircraft to relay messages for another (for example if one aircraft's HF radio has failed they may contact a nearby aircraft on VHF to relay messages to ATC). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because they can usually talk to ATC even when they are out of radar contact airliners can and will provide position reports, and ATC updates their position information the old fashioned way (&lt;a href=&quot;https://aviation.stackexchange.com/questions/492/how-is-aircraft-separation-maintained-when-there-is-no-radar&quot;&gt;which we talked about over here&lt;/a&gt;). The controllers can then assign altitudes, speeds, and headings/routes in such a way that no two aircraft attempt to occupy the same piece of sky at the same time.  (This is generally the way oceanic routes are handled. There are also air-to-air frequencies for aircraft flying these routes so they can coordinate with each other if necessary.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event an aircraft is out of contact with ATC - whether through a radio blind spot, an equipment failure, or for some other reason - they rely on a combination of lost communication procedures (&lt;a href=&quot;https://www.faasafety.gov/files/gslac/courses/content/38/483/Lost%20Com%20Graphic.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here's a quick reference from the FAA&lt;/a&gt;) and &quot;see-and-avoid&quot; (if you &lt;em&gt;see&lt;/em&gt; another aircraft &lt;em&gt;avoid&lt;/em&gt; hitting it) until contact can be re-established.&lt;br&gt;&#xA;The use of standard lost communication procedures also allow the controllers to continue updating the aircraft's position in a non-radar environment (they can estimate progress based on the standard procedures and the aircraft's prior position reports/speed/wind data). A larger block of airspace will be reserved in such situations to account for any error.&lt;/p&gt;&#xA;" OwnerUserId="64" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-08T21:05:36.683" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26777" PostTypeId="1" AcceptedAnswerId="26778" CreationDate="2016-04-08T21:48:15.913" Score="7" ViewCount="2063" Body="&lt;p&gt;Look at this 777 nose:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dRTAk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dRTAk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Air-France/Boeing-777-228-ER/1629826/L/&amp;amp;sid=f5b64c289034832f0433727234e9f35a&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is full of rivets.Why are they so visible on this particular aircraft? Why doesn't the radome have rivets?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-04-08T22:03:00.980" LastActivityDate="2016-04-08T22:11:25.967" Title="Why are these rivets on the 777 so visible?" Tags="&lt;aircraft-maintenance&gt;&lt;fuselage&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26778" PostTypeId="2" ParentId="26777" CreationDate="2016-04-08T22:11:25.967" Score="11" Body="&lt;p&gt;At the risk of sounding ridiculous, the purpose of the rivets is to hold the plane together. More specifically, they hold the outer aluminum skin to the structural skeleton of the aircraft:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/p3YvJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p3YvJ.jpg&quot; alt=&quot;777 skeleton&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(That skeleton happens to be made of &lt;a href=&quot;http://www.seattlepi.com/business/boeing/article/Man-building-Boeing-777-out-of-manila-folders-5169705.php#photo-5766864&quot; rel=&quot;noreferrer&quot;&gt;manilla folders&lt;/a&gt;, but the real one is pretty much identical except that it's bigger and made of metal.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also additional rivets around things like the AOA vane, holding doublers in place to stiffen the skin where these instruments penetrate and create additional load.&#xA;The radome has no rivets as it is a single molded piece of plastic. It does however have structural stiffeners, which you can see running fore-to-aft in the photo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the rivets clearly on this particular aircraft because of the paint scheme (all white) and lighting, however if you look closely you can spot them on any 777 nose.&lt;br&gt;&#xA;Here's one from an aircraft during assembly, and as the interior has not been installed you can also see the skeleton through the windscreen openings:&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/cZ0Rm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cZ0Rm.jpg&quot; alt=&quot;Rivets on a green 777 nose&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="64" LastActivityDate="2016-04-08T22:11:25.967" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26779" PostTypeId="1" AcceptedAnswerId="26781" CreationDate="2016-04-09T02:01:43.057" Score="13" ViewCount="982" Body="&lt;p&gt;Apparently, the MD-87 has a strake on both engines:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Ue5ke.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ue5ke.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://www.airliners.net/photo/Iberia/McDonnell-Douglas-MD-88/0185347/L/&amp;amp;sid=54567eb804d0c8e5a0d38b168dcc3169&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;br /&gt;&#xA;If I'm not wrong, the engine strake attaches the airflow at high angles of attack on the wing. But in this case the engine is behind the wing. So what is the purpose of this little fin? Is it a strake or something else?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="22726" LastEditDate="2020-12-03T00:07:15.583" LastActivityDate="2020-12-03T00:07:15.583" Title="Why does the MD-87 have strakes on its engines?" Tags="&lt;aerodynamics&gt;&lt;engine&gt;&lt;dc-9-family&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26780" PostTypeId="1" AcceptedAnswerId="26782" CreationDate="2016-04-09T05:38:19.223" Score="19" ViewCount="1647" Body="&lt;p&gt;Are simulators owned by airline operators or are they property of private companies who are specialised in this business and offer the services on an outsourcing basis to airlines that require it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm talking about proper simulators like the Airbus or Boeing ones and not PC based ones.&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="64" LastEditDate="2016-07-07T21:05:07.540" LastActivityDate="2017-09-15T05:59:44.560" Title="Are jet simulators a commercial business or are they owned by airlines?" Tags="&lt;flight-simulator&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26781" PostTypeId="2" ParentId="26779" CreationDate="2016-04-09T06:14:20.303" Score="10" Body="&lt;p&gt;They are indeed strakes which serve to reduce flow separation on the lower rear engine fairing by creating a vortex which will mix the outer, faster flow with the slowed down boundary layer on the lower rear part of the fairing. You will notice that the nacelle is &lt;a href=&quot;https://aviation.stackexchange.com/questions/1543/why-do-dc-9-and-md-82-have-engines-that-are-slightly-angled-upwards&quot;&gt;mounted at an angle of 3 degrees to the fuselage&lt;/a&gt;: This is to position the intake and nacelle in line with local airflow, which is pointing slightly downwards at the rear fuselage due to the wing's downwash. The exhaust is again pointing directly back, so the thrust will be aligned with the lengthwise axis of the fuselage and will not produce pitch moment variations when thrust is changed. In combination with the nacelle incidence this produces a more pronounced curvature on the lower side of the nacelle, which in turn is more prone to flow separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could as well place a row of vortex generators on the bottom of the fairing, but the strake will produce less drag when downwash is low and its service is not needed. With higher downwash, the strake will produce a stronger vortex, just when it is needed most.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-09T06:14:20.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26782" PostTypeId="2" ParentId="26780" CreationDate="2016-04-09T07:34:42.180" Score="23" Body="&lt;p&gt;Both!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airlines operate simulator facilities. For example, United has a training &lt;a href=&quot;http://www.amimechanical.com/portfolio-transportation-flight-simulator&quot;&gt;facility in Denver&lt;/a&gt; with a number of simulators. In turn, they &lt;a href=&quot;http://www.unitedtechops.com/news-and-media/docs/svc-bro-flight-training.pdf&quot;&gt;rent out training services&lt;/a&gt; to others who will pay to use the facilities (&lt;a href=&quot;http://www.unitedtechops.com/training/&quot;&gt;more info on their offerings here&lt;/a&gt;). They can also provide trainers, cabin crew training, ground school training, and other such services. Many airlines have similar programs. They've even &lt;a href=&quot;https://exclusives.mileageplus.com/Listing/Details/452400/BehindtheScenes-Flight-Simulator-Travel-Experience&quot;&gt;auctioned off simulator time&lt;/a&gt; to customers willing to bid frequent flyer miles for the privilege. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airline doesn't own and operate the necessary equipment itself (even an airline that runs its own simulators may not have a suitable quantity for every aircraft in its fleet), it can contract for such services from someone else. That someone else might be another airline, a company that provides simulators (&lt;a href=&quot;http://www.superjetinternational.com/wp-content/uploads/A320-FFS-Services-Leaflet-2014.pdf&quot;&gt;example&lt;/a&gt;) and may offer other training services like instructors, or a provider affiliated with the manufacturer (&lt;a href=&quot;http://www.airbus.com/support/training/network/airbus-training-miami/&quot;&gt;example&lt;/a&gt;). &lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2016-04-09T07:34:42.180" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26783" PostTypeId="1" CreationDate="2016-04-09T09:22:58.523" Score="3" ViewCount="581" Body="&lt;p&gt;I am approaching my 18 month mark on the job. Wanting to get my A license first. I have done all kinds of airframe work in this time period. Wondering if anyone has suggestions for the names of the good practice tests books for general and airframe. I have the FAA books on all 3 subjects just no study guides or practice tests. Any suggestions?&lt;/p&gt;&#xA;" OwnerUserId="14393" LastEditorUserId="1696" LastEditDate="2016-04-09T16:35:12.473" LastActivityDate="2019-06-14T20:21:42.803" Title="What are good study guides/practice tests for the airframe maintenance certificate?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;aircraft-maintenance&gt;&lt;airframe&gt;" AnswerCount="1" CommentCount="0" ClosedDate="2019-06-15T11:35:18.150" ContentLicense="CC BY-SA 3.0" />
  <row Id="26784" PostTypeId="2" ParentId="26780" CreationDate="2016-04-09T12:16:41.003" Score="9" Body="&lt;p&gt;In addition to the good information in @ZachLipton's answer, many aviation training companies offer simulator training for aircraft types other than those that most airlines fly, for example the Kodiak, Citation, or King Air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This type of training is often used for training individuals flying their own advanced aircraft or for professional pilots. Pilots flying for corporate or charter outfits will typically do initial and recurrent training with such aviation training facilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Examples of such training facilities would be the &lt;a href=&quot;http://spokaneturbinecenter.com/&quot;&gt;Spokane Turbine Center&lt;/a&gt;, &lt;a href=&quot;https://www.flightsafety.com/fs_reservation.php?pg_xevent=p_clear&quot;&gt;Flight Safety International&lt;/a&gt;, &lt;a href=&quot;http://www.simulator.com/&quot;&gt;SIMCOM Aviation Training&lt;/a&gt;, and many others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to these companies that specialize in aviation training for advanced aircraft, many flight schools that specialize in primary flight training also include training in &lt;a href=&quot;http://www.aerosim.com/productstechnology/proceduretraining/ftdfaalevel6.aspx&quot;&gt;high level FTDs&lt;/a&gt;—which have also been used by &lt;a href=&quot;http://www.wsj.com/articles/SB10001424052702304887904576395850731566080&quot;&gt;some airlines&lt;/a&gt;, at least in the past. Examples of such schools would be &lt;a href=&quot;http://ed.mnsu.edu/aviation/&quot;&gt;MSU&lt;/a&gt; and &lt;a href=&quot;http://flightops.aero.und.edu/&quot;&gt;UND&lt;/a&gt;, among many others.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-04-09T12:16:41.003" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26785" PostTypeId="2" ParentId="26783" CreationDate="2016-04-09T14:44:13.840" Score="3" Body="&lt;p&gt;I used the &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/9872?gclid=CjwKEAjw0KK4BRDCiKHD5Ny8pHESJACLE620llqMaGXAXe6hSzL3NAOlQuGsJlPoB2fcQIzbqH1BvhoC_hrw_wcB&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dale Crane series&lt;/a&gt; of study guides from &lt;a href=&quot;http://www.asa2fly.com/AMT-Test-Guide-Books-C39.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;ASA&lt;/a&gt; years ago, available from either of those two links as well as many other places.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the specific study guide for &lt;a href=&quot;http://www.asa2fly.com/Fast-Track-2016-Test-Guide-Airframe-P2257.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airframe&lt;/a&gt;, but you will also want the &lt;a href=&quot;http://www.asa2fly.com/Fast-Track-2016-Test-Guide-General-P2255C39.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;General&lt;/a&gt; study guide. These are for written test prep, but &lt;em&gt;might&lt;/em&gt; also include Oral and Practical (O&amp;amp;P) test prep.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RIwMp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RIwMp.jpg&quot; alt=&quot;Dale Crane Test Guide Covers&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;em&gt;Image from &lt;a href=&quot;http://images.mypilotstore.com/products/9872.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;mypilotstore.com&lt;/a&gt; product listing&lt;/em&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also other options out there. Gleim offers an &lt;a href=&quot;https://www.gleim.com/aviation/amt/#avTab%3Dmain&quot; rel=&quot;nofollow noreferrer&quot;&gt;AMT test prep course&lt;/a&gt;, as does ASA in their &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/sep/10062&quot; rel=&quot;nofollow noreferrer&quot;&gt;AMT Prepware&lt;/a&gt;, but I don't know that I have any experience with either one. I definitely used one of the digital test prep packages out there, but I can't remember which one. I do like the digital tests, especially since that is probably how you will be taking the writtens anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also studied the &lt;a href=&quot;http://www.mypilotstore.com/MyPilotStore/secp/132&quot; rel=&quot;nofollow noreferrer&quot;&gt;Jeppesen&lt;/a&gt; textbooks in addition to the FAA textbooks you mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will also want to study the &lt;a href=&quot;http://www.mypilotstore.com/mypilotstore/sep/2147&quot; rel=&quot;nofollow noreferrer&quot;&gt;Practical Test Standards (PTS)&lt;/a&gt; for your O&amp;amp;P test prep.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="1696" LastEditDate="2019-06-14T20:21:42.803" LastActivityDate="2019-06-14T20:21:42.803" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26786" PostTypeId="1" AcceptedAnswerId="26805" CreationDate="2016-04-09T18:13:10.557" Score="17" ViewCount="1979" Body="&lt;p&gt;Disks and disk-like objects (frisbees, pie pans, round cardboard piece, hats of all sorts, and many other things) can fly well when thrown along with a spinning force which creates a gyroscopic effect stabilising the object. What causes disk objects to be able to generate lift?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2016-04-09T18:38:43.457" LastActivityDate="2016-04-10T08:01:49.970" Title="How do disks generate lift?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26787" PostTypeId="1" AcceptedAnswerId="26789" CreationDate="2016-04-09T18:49:16.753" Score="13" ViewCount="2195" Body="&lt;p&gt;Have a look at this picture:                                                  &lt;a href=&quot;https://i.stack.imgur.com/UAlK1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UAlK1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's from &lt;a href=&quot;http://www.airliners.net/photo/KLM---Royal/Boeing-747-406/2805594/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt; (though I've modified it a lot) and shows some lines on the fuselage. What are they? Are they Lightning Diverter Strips like in &lt;a href=&quot;https://aviation.stackexchange.com/questions/25020/what-are-these-lines-on-the-nose-of-a-boeing-737&quot;&gt;this question &lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-08-23T07:37:41.193" Title="What are these lines on the fuselage of a 747?" Tags="&lt;boeing-747&gt;&lt;fuselage&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26788" PostTypeId="1" CreationDate="2016-04-09T18:55:49.367" Score="3" ViewCount="136" Body="&lt;p&gt;I am looking for FAA documents and regulations regarding the quality management system for producers of aircraft components.&#xA;Specifically I would like to know what is a &lt;strong&gt;production certificate&lt;/strong&gt; .&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore may I download those regulation somewhere ?&lt;/p&gt;&#xA;" OwnerUserId="8399" LastEditorUserId="19" LastEditDate="2016-08-09T11:30:02.790" LastActivityDate="2016-08-10T18:17:40.180" Title="What regulations govern the quality management system for producers of aircraft components?" Tags="&lt;faa-regulations&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26789" PostTypeId="2" ParentId="26787" CreationDate="2016-04-09T19:32:31.650" Score="22" Body="&lt;p&gt;No, they are just the boundaries between skin panels. See below for a picture of the 747-8 fuselage during assembly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[&lt;img src=&quot;https://i.stack.imgur.com/dhxBD.jpg&quot; alt=&quot;Boeing 747-8 front from side[1]&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-8 front from side (picture &lt;a href=&quot;http://www.cnet.com/pictures/where-boeings-next-gen-747-8-comes-to-life-photos/13/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And this is how the panels for the cylindrical section look like before they are joined:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Su30t.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Su30t.jpg&quot; alt=&quot;Boeing 747-8 panel skins&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 747-8 fuselage panels. The original picture (&lt;a href=&quot;http://www.cnet.com/pictures/where-boeings-next-gen-747-8-comes-to-life-photos/34/&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) is named &quot;wing panel skins&quot;, but these are really fuselage parts.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-04-09T19:32:31.650" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26790" PostTypeId="1" AcceptedAnswerId="26834" CreationDate="2016-04-09T19:45:07.987" Score="2" ViewCount="198" Body="&lt;p&gt;I get the basics of autorotation when it comes to a helicopter in unpowered flight, but it's a bit unclear to me when it comes to quadrotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My objective is to cover some directed horizontal distance while in freefall and resume control before crashing. I want to do this to save battery, rather than starting controlled flight from the start. If I get horizontally closer to a target location without using much any battery, this is optimal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say the quad has stable attitude and is in free fall. Then I brake one motor, causing the prop to stop. A naive freebody diagram says the quad will pitch since there's no longer any lift on that side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is what happens after that. Does it reach some &lt;strong&gt;equilibrium position&lt;/strong&gt;? Does the decreased upward lift yield &lt;strong&gt;horizontal acceleration&lt;/strong&gt; relative to the ground, or will it just &lt;strong&gt;spin in a circle&lt;/strong&gt;? Do the rotation directions of the remaining props (2CW/1CCW or 2CCW/1CW) affect what happens next? What if I cut off 2 motors, either next to each other or across from each other?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you.&lt;/p&gt;&#xA;" OwnerUserId="14396" LastEditorUserId="1696" LastEditDate="2016-04-11T21:25:50.030" LastActivityDate="2016-04-11T21:41:43.220" Title="What happens if one or more rotors are stopped during autorotation on a quadrotor?" Tags="&lt;auto-rotation&gt;&lt;quadcopter&gt;" AnswerCount="1" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="26791" PostTypeId="2" ParentId="26788" CreationDate="2016-04-09T19:54:24.687" Score="4" Body="&lt;p&gt;From FAA, &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/production_approvals/prod_cert/&quot; rel=&quot;nofollow&quot;&gt;Production Certificate&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A production certificate is an approval (document) to manufacture&#xA;  duplicate products under an FAA-approved type design (e.g., type&#xA;  certificate or supplemental type certificate). The holder of a&#xA;  production certificate may obtain an airworthiness certificate for&#xA;  aircraft produced under the production certificate without further&#xA;  showing. To obtain one, the production application and approval&#xA;  process must be followed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;See also: &#xA;Production Approval - Regulations &amp;amp; Policies (&lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/production_approvals/prod_cert/pc_regs/&quot; rel=&quot;nofollow&quot;&gt;link&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-04-09T19:54:24.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26792" PostTypeId="1" CreationDate="2016-04-10T00:00:50.940" Score="6" ViewCount="391" Body="&lt;p&gt;Is a transponder needed to be turned on to operate above the upper limit of class B airspace?&lt;/p&gt;&#xA;" OwnerUserId="14397" LastEditorUserId="1696" LastEditDate="2016-04-10T00:43:34.883" LastActivityDate="2016-04-10T04:51:13.110" Title="Does the transponder need to be on in the upper limit of Class B airspace?" Tags="&lt;faa-regulations&gt;&lt;transponder&gt;&lt;class-b-airspace&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26794" PostTypeId="1" AcceptedAnswerId="26798" CreationDate="2016-04-10T00:22:14.283" Score="7" ViewCount="2037" Body="&lt;p&gt;Let's find a runway where there are localizer-related procedures at both ends, e.g. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;KMRY: 110.7 for both &lt;a href=&quot;http://flightaware.com/resources/airport/MRY/IAP/ILS+OR+LOC+RWY+10R/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS RWY 10R&lt;/a&gt; and &lt;a href=&quot;http://flightaware.com/resources/airport/MRY/IAP/LOC_DME+RWY+28L/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;LOC/DME RWY 28L&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;KLAX: 108.5 for both &lt;a href=&quot;http://flightaware.com/resources/airport/LAX/IAP/ILS+OR+LOC+RWY+06L/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS OR LOC RWY 06L&lt;/a&gt; and &lt;a href=&quot;http://flightaware.com/resources/airport/KLAX/IAP/ILS+OR+LOC+RWY+24R/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ILS OR LOC RWY 24R&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, this doesn't align with the ILS back course concept. When I fly one procedure, how can I can tell that I am not on the back course of the other? Getting down to instrument interpretation, for an HSI, how to set the front course? In a traditional VOR, is it positive or negative sensing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;POST EDIT: &#xA;Tried in a SIM, it seems that when well above the slope, it shows back course. When I get lower, it shows front course.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7eAi7.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7eAi7.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="13197" LastEditDate="2016-04-16T21:37:32.357" LastActivityDate="2016-04-16T21:37:32.357" Title="Why do double-ended ILS runway share the same frequency from both sides?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26795" PostTypeId="2" ParentId="26792" CreationDate="2016-04-10T00:22:30.507" Score="3" Body="&lt;p&gt;Yes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, Class B airspace extends up to 10,000ft. That said, FAA states that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;All aircraft are required to be equipped with a Mode C transponder&#xA;  when flying at or above 10,000 feet msl, over the 48 contiguous states&#xA;  or the District of Columbia, excluding that airspace below 2,500 feet&#xA;  agl.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="11136" LastActivityDate="2016-04-10T00:22:30.507" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26798" PostTypeId="2" ParentId="26794" CreationDate="2016-04-10T00:28:02.600" Score="9" Body="&lt;p&gt;Listen to the identifier... That will tell you if you have the 10R I-MRY or the 28L I-MTB ils.  Some runways use the same frequency like this, while others use different frequencies for opposite direction ILS's.  The identifier will always be unique, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 10R transmitter doesn't operate at the same time as the 28L transmitter. One transmits &quot;this&quot; ils beam in &quot;this&quot; direction using &quot;this&quot; ident on whatever frequency; the other transmits a different ils beam in a different direction using a different ident; the fact that it is or is not the same frequency is incidental.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Usually, the two reciprocal ILS's to the same length of pavement use the same frequency, with one switched off when the other is switched on.  MRY in the OP is a good example of this, and most other airports I looked at have the same behavior, but this is not universal.  Reno, NV -- KRNO -- is an example where the opposite ILS's are &lt;strong&gt;not&lt;/strong&gt; on the same frequency: 16R ils is 110.9, but 34L ils is 109.9. Same pavement, different frequencies.  Also, Detroit, MI -- KDTW -- appears to have two full ILS's set up for runway 4R/22L, with one pair on 111.75, and the other on 111.95.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One other note: the various flight simulator programs may or may not accurately model this behavior.  Some may simply have every ILS &quot;on&quot; at the same time, so if you're west of &quot;this&quot; airport, you'll receive the ILS for landing east, and vice versa.  Works well for a flight simulator program, but that's not how the real world works.  It takes a call to tower to have the one ILS turned off and the other turned on, and it isn't something they prefer to do repeatedly or on short notice.  In the sim, it's convenient to fly approaches back &amp;amp; forth to 16C then 34C then 16C and so on, but even if traffic permitted, in the real world they'd probably prefer you flew your ILS's to one runway, and use something that doesn't need the ILS or the LOC when landing in the opposite direction.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-04-11T14:37:28.297" LastActivityDate="2016-04-11T14:37:28.297" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26800" PostTypeId="2" ParentId="26792" CreationDate="2016-04-10T04:51:13.110" Score="7" Body="&lt;p&gt;Yes:&#xA;If you combine the two sections provided by SMSvonder Tann and Raaj Tram you get: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;14 CFR 91.215 - ATC transponder and altitude reporting equipment and use:&lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(b)(4) All aircraft in all airspace above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL; and&lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(b)(5)(I) airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You can't fly over B or C without a transponder. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some specific exceptions for aircraft not originally equipped with an electrical system.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-04-10T04:51:13.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26801" PostTypeId="1" AcceptedAnswerId="26806" CreationDate="2016-04-10T05:40:38.443" Score="9" ViewCount="4071" Body="&lt;p&gt;I was watching &lt;a href=&quot;https://youtu.be/9pBHB7tYceg?t=197&quot; rel=&quot;noreferrer&quot;&gt;this&lt;/a&gt; youtube video and I noticed that at 3:17 seconds they show a coast guard helicopter rescuing a man from a ship. Whats shocking about this is that the main rotor of the helicopter seem to be going incredibly slowly and the tail rotor has completely stopped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How was the helicopter able to stay flying with such a low rotational speed? Was this some optical illusion or was the rotor really spinning that slowly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, how was the helicopter not spinning? From what I understand the main purpose of the rear rotor is to counteract the rotational force of the main rotor. Since the rear rotor wasn't moving, shouldn't the helicopter developed a spin counter to the spin of the main rotor (even though it was slow)?&lt;/p&gt;&#xA;" OwnerUserId="2265" LastActivityDate="2017-12-15T01:17:13.990" Title="Can a helicopter really fly with rotors going this slow?" Tags="&lt;helicopter&gt;&lt;airspeed&gt;&lt;rotorcraft&gt;&lt;spins&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26802" PostTypeId="2" ParentId="18811" CreationDate="2016-04-10T05:46:27.200" Score="1" Body="&lt;p&gt;For a given horsepower two blades are more efficient than three, three more than four, and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few reasons to have more than two blades:&lt;br&gt;&#xA;-the engine generates so much power that a two blade prop would need to be so long that it would contact the ground.&lt;br&gt;&#xA;-the engine generates so much power that a two blade prop would need to be so long that the velocity of the blade tips would exceed the speed of sound.&lt;br&gt;&#xA;-the application of the aircraft requires acceleration and climbing ability over top speed.  More blades for a given power equate to slower top speeds but better takeoff acceleration and rates of climb.&lt;br&gt;&#xA;-in the case of the V-tail Bonanza, the added weight of the three blade moves the CG forward making loading easier.&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most efficient prop for a given hp is a single blade (it exists).  Plenty of examples in Google images.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost and manufacturing/maintenance aspect are other considerations and have been addressed in other answers.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-04-10T05:57:27.857" LastActivityDate="2016-04-10T05:57:27.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26804" PostTypeId="1" CreationDate="2016-04-10T07:27:54.997" Score="11" ViewCount="1143" Body="&lt;p&gt;When in a peak load scenario with plenty of departing &amp;amp; arriving aircraft to keep the ATC pipeline full, are there considerations that make a certain sequence of Departures / Arrivals that optimizes throughput?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For specificity, let us assume a single runway in use and no general aviation aircraft with predominantly jet traffic and multiple runway entry &amp;amp; exit taxiways available. Including high speed exit turnoffs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I typically see a sequence something like:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt; Dep-Dep-Arr-Dep-Dep-Arr&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;But an alternative optimum might turn out to be:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Dep-Arr-Dep-Arr-Dep-Arr&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I realize that the specifics will depend on the exact aircraft etc. but just to use an idealized model what would result from typical operating constraints. e.g. You need to allow a certain separation during approach but you can have multiple aircraft lined up for take off. So is the potential to squeeze departures into the &quot;holes&quot; higher? Also, you can clear a second departure after a first far more rapidly, than the landing-to-landing interval right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just wondering, if you had to set up a formal optimization model what sort of parameters &amp;amp; constraints should go into the model as inputs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A follow up question:&lt;/strong&gt; Say you had two runways available in parallel &amp;amp; widely spaced apart. Does it make sense (for throughput) to dedicate one to landings &amp;amp; another to takeoffs or is it more efficient to mix landings &amp;amp; takeoffs on both runways? &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R18L: Dep-Dep-Dep-Dep-Dep-Dep-Dep-Dep-Dep&#xA;R18R: Arr-Arr-Arr-Arr-Arr-Arr-Arr-Arr-Arr&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;vs &lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;R18L: Dep-Dep-Arr-Dep-Dep-Arr-Dep-Dep-Arr&#xA;R18R: Dep-Dep-Arr-Dep-Dep-Arr-Dep-Dep-Arr&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;PS.&lt;/strong&gt; If further simplifying assumptions are necessary, let's imagine a hypothetical airport serving a single aircraft type, say A320 only. Or assume any type you will to be representative of a wide class of aircraft just to get the modelling started. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="19" LastEditDate="2016-07-11T14:36:32.827" LastActivityDate="2016-07-11T14:36:32.827" Title="What is the optimal sequence of departures and arrivals on a single runway?" Tags="&lt;air-traffic-control&gt;&lt;landing&gt;&lt;takeoff&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26805" PostTypeId="2" ParentId="26786" CreationDate="2016-04-10T08:01:49.970" Score="15" Body="&lt;p&gt;As with regular wings, the angle of attack and the dynamic pressure determine the lift of a frisbee.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://web.mit.edu/womens-ult/www/smite/frisbee_physics.pdf&quot; rel=&quot;noreferrer&quot;&gt;This short paper by V. Morrison&lt;/a&gt; gives a short overview. If you want to dig deeper, &lt;a href=&quot;http://biosport.ucdavis.edu/research-projects/frisbee-flight-simulation-and-throw-biomechanics/HummelThesis.pdf&quot; rel=&quot;noreferrer&quot;&gt;Sarah Hummel&lt;/a&gt; and &lt;a href=&quot;https://www.researchgate.net/publication/242123705_The_Physics_of_Frisbees&quot; rel=&quot;noreferrer&quot;&gt;Eugene Motoyama&lt;/a&gt; (sorry, paywalled) have done more detailed work on flying discs. The following pictures were shamelessly copied from the work of &lt;a href=&quot;https://math.la.asu.edu/~nbrewer/Spring2010/HonorsProjects/Kevin_Walsh_MAT266.pdf&quot; rel=&quot;noreferrer&quot;&gt;Kevin Walsh&lt;/a&gt;. They show that the rounded edge improves airflow over the disc by delaying flow separation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/elLNi.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/elLNi.jpg&quot; alt=&quot;Flow around a frisbee&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow around a frisbee (&lt;a href=&quot;https://math.la.asu.edu/~nbrewer/Spring2010/HonorsProjects/Kevin_Walsh_MAT266.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The frisbee can be seen as a wing with an &lt;a href=&quot;https://aviation.stackexchange.com/questions/19122/aerofoil-wing-that-gives-reasonably-good-lift-for-both-air-flow-directions-fo&quot;&gt;airfoil that looks the same from both directions&lt;/a&gt;. This incurs a small separation area at the rear end, but prevents much larger separation at the leading edge at medium angles of attack. Morrison found the farthest flying distances with an angle of attack of 12° and a starting speed of 14 m/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the center of pressure is close to the leading edge, a disc would quickly topple over due to the different locations of the center of pressure and the center of gravity. By spinning, it can be stabilized:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rx4cT.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rx4cT.png&quot; alt=&quot;Difference between spinning and non-spinning frisbee&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Difference between spinning and non-spinning frisbee (&lt;a href=&quot;https://math.la.asu.edu/~nbrewer/Spring2010/HonorsProjects/Kevin_Walsh_MAT266.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;). Inertia / &lt;a href=&quot;https://en.wikipedia.org/wiki/Gyroscope&quot; rel=&quot;noreferrer&quot;&gt;gyro forces&lt;/a&gt; prevents the spinning frisbee from pitching up.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-04-10T08:01:49.970" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26806" PostTypeId="2" ParentId="26801" CreationDate="2016-04-10T11:59:39.593" Score="33" Body="&lt;p&gt;It's an illusion that the blades appear to be going slowly. It's actually a well known effect called the &lt;a href=&quot;https://en.wikipedia.org/wiki/Wagon-wheel_effect&quot;&gt;wagon wheel effect&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially the rotor is spinning at close to an even multiple of the camera's framerate divided by the number of rotors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that between frames the blades have moved a full quarter rotation (or a multiple of that). Creating the illusion that the rotor is moving more slowly that it actually is.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2016-04-10T19:38:24.780" LastActivityDate="2016-04-10T19:38:24.780" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26807" PostTypeId="2" ParentId="26754" CreationDate="2016-04-10T14:16:28.083" Score="4" Body="&lt;p&gt;There is a description of this route page &lt;a href=&quot;http://www.yumpu.com/en/document/view/11490268/ap-1b-cnatra&quot; rel=&quot;nofollow noreferrer&quot;&gt;1-139 of &quot;Area Planning, MTR&quot;&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c4zBl.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c4zBl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The scan is not good, you may get the textual content &lt;a href=&quot;ftp://ftp2.dot.state.mn.us/pub/outbound/Aeronautics/GIS/56DySubscription_June_30__2011_-_August_25__2011/Additional/MTR.txt&quot; rel=&quot;nofollow noreferrer&quot;&gt;here too&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It says terrain following activities &lt;em&gt;may&lt;/em&gt; take place, as well as visual contours (which I assume to be navigating without radar, looking at the outdoor and searching in a catalog the same relief contour to know where you are). As you commented, taking into account the local relief:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;For terrain following should be for newbies.&lt;/li&gt;&#xA;&lt;li&gt;For visual contours navigation should be for top-guns only.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are different routes like this, starting from nowhere and ending in the Smoky MOA. They seem to be routes avoiding nearby airfields. On the image below, I've emphasized the area without airfields, including MOAs. It looks like IR-504 is drawn along the centerline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zeGAS.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zeGAS.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Based on &lt;a href=&quot;http://vfrmap.com/?lat=38.3&amp;amp;lon=-95&amp;amp;zoom=10&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFRMAP&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other possible selection criteria:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Unpopulated areas (noise from low flying jets)&lt;/li&gt;&#xA;&lt;li&gt;Low radio noise areas.&lt;/li&gt;&#xA;&lt;li&gt;Flat terrain for UAV training.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-04-10T14:29:29.680" LastActivityDate="2016-04-10T14:29:29.680" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26808" PostTypeId="1" CreationDate="2016-04-10T14:23:57.073" Score="24" ViewCount="5225" Body="&lt;p&gt;Assume you enter a cloud with no visibility of the horizon. Your glider is not equipped with an artificial horizon, turn speed indicator or the like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You must fly within safe limits, using air speed, ball, yarn, compass, variometer, altimeter and what basic instruments are available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this possible, and how difficult is it? Can most &quot;normally skilled&quot; pilots do that without extensive previous training? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if you just correct the yarn with the ailerons, the speed with the elevator and keep rudder neutral or fly a fixed compass heading, is that likely to keep you flying safely until you're out of the cloud?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&#xA;I now remember an old &quot;story&quot;. I am not sure I remember it correctly though. What is certain is that in the &quot;old days&quot; some instruments were sometimes sealed before a competition, in order to (try to) make it impossible to go into clouds. I think it was the turn speed indicator and also the compass? But some pilots were caught cheating by bringing a small compass in their pocket.&#xA;OK, I am not sure I am telling this story correctly. (Nowadays they check GPS logs and compare to cloud base altitude.) If I remember correctly, these pilots were willing to fly in clouds and also curve using only primary instruments.&lt;/p&gt;&#xA;" OwnerUserId="14245" LastEditorUserId="14245" LastEditDate="2016-04-11T16:23:32.917" LastActivityDate="2019-03-15T19:42:39.313" Title="Can you fly a glider in a cloud on primary instruments?" Tags="&lt;glider&gt;&lt;ifr-navigation&gt;" AnswerCount="9" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26809" PostTypeId="2" ParentId="26808" CreationDate="2016-04-10T14:36:25.050" Score="10" Body="&lt;p&gt;It would be difficult to stay stable for any length of time because those basic instruments give you almost no information on your angle of bank. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you could manage to keep your spirit compass on a constant heading and keep the yarn straight, your wings would be level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So while it would be possible, I would think you would need an experienced glider pilot and relatively calm conditions to maintain wings level for any usable length of time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be interesting to hear from someone who has actually done it.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="595" LastEditDate="2016-04-10T15:05:15.877" LastActivityDate="2016-04-10T15:05:15.877" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26810" PostTypeId="2" ParentId="26804" CreationDate="2016-04-10T14:50:10.073" Score="8" Body="&lt;p&gt;Usually a mixed usage runway is more efficient than a dedicated arrival runway(s). Arrivals are harder to get closer together than departures as well. Running a final with 5 mile gaps(for wake and all departures) is a good way to do dep-arr-dep-arr.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With dedicated Dep-Arr runways, and assuming you have aircraft ready to go, your expected hourly rate for Arrival only runways is usually around 30, whereas with a departure only runway the rate is about 45 or so(assuming minimal spacing, and have decent fan headings, and the departure routes are split decently to allow good separation heading to the center).&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-04-10T14:50:10.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26811" PostTypeId="2" ParentId="26808" CreationDate="2016-04-10T15:56:39.153" Score="15" Body="&lt;p&gt;Yes it is possible to fly in cloud in a glider. In fact there is an &lt;a href=&quot;https://members.gliding.co.uk/library/pilots/bga-cloud-flying-endorsement-application-form/&quot; rel=&quot;nofollow noreferrer&quot;&gt;endorsement&lt;/a&gt; for it for your licence with an exam. (In the UK anyway.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does only require primary instruments, the one used for cloud flying is called a turn and slip, showing bank and yaw. Along with the yaw string. These are found in almost all gliders I have come across. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is generally an endorsement only held by otherwise experienced pilots, and isn't done for prolonged periods of time. But, you are then licensed to do so. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is easy to become disorientated, and be in odd angles of attack etc. So you must learn not to trust your feeling. I have heard of goggles used in training to cloud your vision. &lt;/p&gt;&#xA;" OwnerUserId="11884" LastEditorUserId="11884" LastEditDate="2018-01-30T21:56:39.943" LastActivityDate="2018-01-30T21:56:39.943" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26812" PostTypeId="2" ParentId="26808" CreationDate="2016-04-10T16:01:32.680" Score="33" Body="&lt;p&gt;With basic instruments (altimeter, speed and climb indicator and compass): Forget it!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A glider can enter a cloud when thermalling into it from below. Below the cloud the rising air was governed by dry adiabatic laws. Once it crosses into the cloud, the air is fully saturated and humidity starts to condense - after all, this is how clouds form. Now the rising air gets additional energy from condensation (its lapse rate goes down from the usual degree per 100 m of the dry adiabatic lapse rate to half a degree per 100 m) and the thermals inside the cloud become stronger. This is to say that turbulence will be more violent and the airplane will be tossed around. It will bank and pitch, and there is little chance that it will stay level for long. Since the spiral dive motion has very little damping, the glider will soon enter a spiral dive and overspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advice I got for the case that you are &quot;sucked&quot; into the cloud always was: Let go of the stick and open the speed brakes. Then wait until it gets light again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the 1930's some competition pilots tried to gain additional altitude by entering clouds. The results were catastrophic. In some cases the cover of the wings was torn to shreds by hail, and even bailing out would not be safe: One pilot froze to death when strong thermals inside the cloud lifted him to more than 8000m while he hung on his parachute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have done it once on a calm day when returning from the Alps. In the mountains the cloud base is higher, so it is entirely possible to arrive at the clouds over the alpine upland above their base height. I had a GPS on board that told me that I would reach the glider port safely when flying a straight line. It was late in the day, the thermals had died down and the clouds were fuzzy already, so little turbulence could be expected. One was in my way, and I went into it and flew out less than a minute later. The whole thing was completely uneventful, but I would not had done it with active thermals.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-04-10T16:48:26.190" LastActivityDate="2016-04-10T16:48:26.190" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26813" PostTypeId="2" ParentId="26801" CreationDate="2016-04-10T17:29:31.413" Score="7" Body="&lt;p&gt;Many things give similar effects. Strobe lights are popular with dance and and other entertainment venues. One game was to adjust the strobe timing so a spinning wheel would look like it was going backwards, then forwards, then standing still, and so on until you grew tired of the game. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Watch old movie westerns and the wheels sometimes look like they are going backwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the days of old CRT monitors TV shows had to use special electronics with TVs filmed on show sets to avoid the video appearing to break up or doing other funny things. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can get a simple strobe effect with many modern LED Christmas light strings. Move your eyes rapidly so your vision crosses the lights and you may well see the lights appear to flash. Actually, they are always flashing. It is just that they are flashing faster than the eye can normally notice. &lt;/p&gt;&#xA;" OwnerUserId="14408" LastEditorUserId="14408" LastEditDate="2016-04-17T23:01:15.973" LastActivityDate="2016-04-17T23:01:15.973" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26815" PostTypeId="1" AcceptedAnswerId="26817" CreationDate="2016-04-10T18:42:44.010" Score="10" ViewCount="9960" Body="&lt;p&gt;The newest planes like the 787 or A350 have a different kind of cockpit windshields:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rgDPk.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rgDPk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture &lt;a href=&quot;http://www.airliners.net/photo/United-Airlines/Boeing-787-9-Dreamliner/2623611/L/&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A350 has &quot;black&quot; windshields:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/sH2S5.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sH2S5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Qatar-Airways/Airbus-A350-941/2602827/L/&amp;amp;sid=78fbff0103b0095d9bf3783c9eb3569e&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does anybody know why are the windshields different? &lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="595" LastEditDate="2016-04-10T18:51:28.320" LastActivityDate="2017-01-28T23:20:07.660" Title="Why are the cockpit windshields on the A350 black?" Tags="&lt;cockpit&gt;&lt;airbus-a350&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26817" PostTypeId="2" ParentId="26815" CreationDate="2016-04-11T01:19:49.283" Score="11" Body="&lt;p&gt;The gold tint on the 787 window is a conductive coating for de-icing. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Dreamliner jet flight-deck crews will view the world through commercial aviation's largest windshields by PPG, kept clear of fog and ice with gold and indium-tin oxide heating systems. &lt;sup&gt;&lt;a href=&quot;http://investor.ppg.com/phoenix.zhtml?c=112929&amp;amp;p=irol-newsArticle&amp;amp;ID=1383368&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The A350 also has a windshield anti-ice system. It is referred to in &lt;a href=&quot;https://i.stack.imgur.com/vkIDc.jpg&quot; rel=&quot;noreferrer&quot;&gt;this answer&lt;/a&gt;. One thing both aircraft have in common is that they use &lt;a href=&quot;http://bloga350.blogspot.com/2012/12/a350-xwb-first-curved-windows-airbus-is.htmlhttp://bloga350.blogspot.com/2012/12/a350-xwb-first-curved-windows-airbus-is.html?m=1&quot; rel=&quot;noreferrer&quot;&gt;curved windshields&lt;/a&gt;. I'm not sure if that adds to the black look. But what &lt;strong&gt;does&lt;/strong&gt; add to the black sunglasses look is that the window frames are painted black.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/vkIDc.jpg&quot; alt=&quot;A350 windscreen&quot;&gt;&#xA;&lt;a href=&quot;http://www.a350xwb.com/fileadmin/media_gallery/photogallery/big/1600x1200_1418316757_A350_XWB_MSN3_NOSE_CLOSE_UP.jpg&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Btw: There's a &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/6140825/&quot; rel=&quot;noreferrer&quot;&gt;thread on Airliners.net&lt;/a&gt; where most of them seem to despise the black window frames.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-04-12T03:05:30.040" LastActivityDate="2016-04-12T03:05:30.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26818" PostTypeId="2" ParentId="26756" CreationDate="2016-04-11T07:11:11.400" Score="13" Body="&lt;p&gt;&lt;strong&gt;Introduction to Transonic Aerodynamics&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Roelof Vos, Saeed Farokhi&lt;/em&gt; (&lt;a href=&quot;https://books.google.com/books?id=KG3xCAAAQBAJ&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lorLY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lorLY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Written to teach students the nature of transonic flow and its&#xA;  mathematical foundation, this book offers a much-needed introduction&#xA;  to transonic aerodynamics. The authors present a quantitative and&#xA;  qualitative assessment of subsonic, supersonic and transonic flow&#xA;  around bodies in two and three dimensions. The book reviews the&#xA;  governing equations and explores their applications and limitations as&#xA;  employed in modeling and computational fluid dynamics.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Transonic Aerodynamics of Airfoils and Wings&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;W.H. Mason&lt;/em&gt; (&lt;a href=&quot;http://www.dept.aoe.vt.edu/~mason/Mason_f/ConfigAeroTransonics.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hVWfw.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hVWfw.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Professor emeritus by the Virginia Tech, expert in aerospace&#xA;  engineering who worked at Grumman Aerospace where he served in the&#xA;  structural mechanics section and later in aerodynamics and worked on a&#xA;  number of high-profile projects, including the Grumman X-29. Has&#xA;  taught classes — including his &quot;famous&quot; Configuration Aerodynamics&#xA;  course.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Review of NASA Supercritical Airfoils&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Richard T. Whitcomb&lt;/em&gt; (&lt;a href=&quot;http://crgis.ndc.nasa.gov/crgis/images/5/59/Review_SC_Airfoils.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0lic4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0lic4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NASA supercritical airfoils are characterized by a substantially&#xA;  reduced curvature of the midcord region of the upper surface together&#xA;  with increased camber near the trailing edge. The basic aerodynamic&#xA;  phenomena associated with the airfoils and representative wind tunnel&#xA;  results are discussed. The results indicate that the drag rise Mach&#xA;  numbers for NASA supercritical airfoils are 0.1 higher than for&#xA;  comparable NACA 6-series airfoils. A recent analytic method for&#xA;  predicting the aerodynamic characteristics of supercritical airfoils&#xA;  is described. The flight demonstration programs of three applications&#xA;  of supercritical airfoils utilizing the F-8, T-2C and F-111 as test&#xA;  beds are summarized.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Richard_T._Whitcomb&quot; rel=&quot;nofollow noreferrer&quot;&gt;Richard T. Whitcomb&lt;/a&gt; on Wikipedia.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;NASA Supercritical Airfoils, A Matrix of Family-Related Airfoils&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Charles D. Harris&lt;/em&gt; (&lt;a href=&quot;https://ntrs.nasa.gov/search.jsp?R=19900007394&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/13d6h.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/13d6h.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The NASA supercritical airfoil development program is summarized in a&#xA;  chronological fashion. Some of the airfoil design guidelines are&#xA;  discussed, and coordinates of a matrix of family related supercritical&#xA;  airfoils ranging from thicknesses of 2 to 18 percent and over a design&#xA;  lift coefficient range from 0 to 1.0 are presented.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Supercritical Airfoil Design for Future HALE Concepts&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Kasim Biber, Carl P. Tilmann&lt;/em&gt; (&lt;a href=&quot;http://aircraftdesign.nuaa.edu.cn/MDO/ref/Application/Jointed_wing/Supercritical%20airfoil%20design%20for%20future%20HALE%20concepts%5EHigh-Altitude%20Long-Endurance%20aircraft.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tyweG.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tyweG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This paper presents design and analysis of a new airfoil for future&#xA;  High-Altitude Long-Endurance (HALE) aircraft that has an operational&#xA;  condition at supercritical speeds. The XFOIL and MSES computational&#xA;  codes were used to design, modify and analyze the airfoil.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Design of Laminar Supercritical Airfoils Based on Navier-Stokes Equations&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Zhong-Hua HAN, Jie DENG, Jun LIU,  Ke-Shi, ZHANG, Wen-Ping SONG&lt;/em&gt; (&lt;a href=&quot;http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/575.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J6lPp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J6lPp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This paper aims to develop a suit of design methods and&#xA;  tools for laminar supercritical airfoils, based on &#xA;  high-fidelity computational fluid dynamics (CFD). The reliable &#xA;  transition perdition method, efficient inverse design and &#xA;  global optimization design methods are regarded as &#xA;  three key issues, which are addressed in this paper. The automatic &#xA;  transition prediction method coupling Navier-Stokes equations &#xA;  flow solver and eN linear &#xA;  stability analysis method is applied to the design and analysis of the&#xA;  laminar supercritical airfoils; inverse design and optimization design&#xA;  methods based on kriging surrogate model is developed to &#xA;  attain favorable pressure gradient while reducing wave &#xA;  drag; efficient optimization based on kriging model and an &#xA;  improved EI (expected improvement) method is developed for finding &#xA;  the global optimum.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;NASA Technical Memorandum 103933 An Experimental Investigation of a Supercritical Airfoil at Transonic Speeds&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;George G. Mateer, H. Lee Seegmiller, Lawrence A. Hand and Joachim Szodruch&lt;/em&gt; (&lt;a href=&quot;https://ia800502.us.archive.org/0/items/nasa_techdoc_19930015345/19930015345.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/65kES.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/65kES.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Benchmark experimental data obtained in the two-dimensional, transonic&#xA;  flow field surrounding a supercritical airfoil are presented. Airfoil&#xA;  surface and tunnel wall pressure and LDV measurements are used to&#xA;  describe the flow on the model, above the wing and in the wake.&#xA;  Comparisons are made with calculations using the Reynolds-averaged&#xA;  Navier-Stokes equations. The results illustrate the performance of two&#xA;  turbulence models in both separated and attached flows. The largest&#xA;  differences between theory and experiment occurred in separated flows&#xA;  with the Johnson and King turbulence model providing the best&#xA;  estimates.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Analysis of Aerodynamic Characteristics of a Supercritical Airfoil for Low Speed Aircraft&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;P.Sethunathan, M.Niventhran, V.Siva, R.Sadhan Kumar&lt;/em&gt; (&lt;a href=&quot;https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780022113.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/itPU4.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/itPU4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The main goal of the proposed paper is the analysis of aerodynamic&#xA;  characteristics of an various supercritical airfoils like 0406, 0412,&#xA;  0706 and 1006 influence on the  dramatic improvement in lift and&#xA;  reduction of drag in low speed aircraft. In a precedent work,  a  cusp &#xA;  like  structure  at  the  trailing  edge  of  an  unsymmetrical &#xA;  airfoil  produces a  very  high  improvement  in  climbing performance&#xA;  of an aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Two-dimensional Wind-tunnel Tests of a NASA Supercritical Airfoil with Various High-lift Systems&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;E. Omar et Al.&lt;/em&gt; (&lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19800003804&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4U9ev.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4U9ev.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Three high lift systems for a 9.3 percent blunt based, supercritical&#xA;  airfoil were designed, fabricated, and wind tunnel tested. A method&#xA;  for calculating the viscous flow about two dimensional multicomponent&#xA;  airfoils was evaluated by comparing its predictions with test data. A&#xA;  comparison of high lift systems derived from supercritical airfoils&#xA;  with high lift systems derived from conventional airfoils is&#xA;  presented. The high lift systems for the supercritical airfoil were&#xA;  designed to achieve maximum lift and consisted of: (1) a single&#xA;  slotted flap, (2) a double slotted flap and a leading edge slat, and&#xA;  (3) a triple slotted flap and a leading edge slat.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Aerodynamic Characteristics of an 11-percent-thick Symmetrical Supercritical Airfoil at Mach Numbers Between 0.30 and 0.85&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Blackwell, J. A., Jr.&lt;/em&gt; (&lt;a href=&quot;http://ntrs.nasa.gov/search.jsp?R=19830002814&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;)  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xnNWA.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xnNWA.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Abstract: The aerodynamic characteristics of an 11 percent thick&#xA;  symmetrical supercritical airfoil were determined in an 8 foot&#xA;  transonic pressure tunnel over a Mach number range of 0.30 to 0.85.&#xA;  The Reynolds number of the tests, based on the airfoil chord, varied&#xA;  with Mach number over a range of 360 million to 774 million. The&#xA;  geometric angle of attack varied from -0.5 to 10.5 deg. The abrupt&#xA;  drag rise for the supercritical airfoil at zero normal force&#xA;  conditions occurs at a Mach number just above 0.82. The corresponding&#xA;  drag rise Mach number for a conventional NACA 0012 airfoil is&#xA;  approximately 0.70. At zero normal force conditions, the level of&#xA;  supervelocity over the supercritical airfoil is considerably reduced&#xA;  from that for the NACA 0012 airfoil. Also, the shock wave for the&#xA;  supercritical airfoil is substantially weaker than that for the NACA&#xA;  0012 airfoil.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-11-05T15:10:17.613" LastActivityDate="2019-11-05T15:10:17.613" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="26821" PostTypeId="2" ParentId="26808" CreationDate="2016-04-11T12:15:35.663" Score="4" Body="&lt;p&gt;I've done it many times to climb slightly into the cloud (in situations when the risk to meet with another fellow in the cloud is low, i.e. far from any airfield and there are quite lot of useful clouds nearby). Immediately after losing visual to the ground I level wings and quickly find my way out of the cloud. Punching a hole on the side of the cloud and scooting into sunlight with 200km/h is something what I really like in flying gliders :) But this is not real IMC flight just biting a bit into the cloud. I once tried that how long I can maintain spiraling in a cloud just by pants (so w/o turn indicator). And even a slight turbulence was enough to confuse my senses, so I opened speedbreak and left the cloud. What surprised me was that I entered into cloud in a left spiral and descended out of it in a right spiral - without even noticing this direction change. Important fact that I done this experiment in a glider which has speedbrake effective enough the keep the speed below Vne even in vertical dive (fortunately I didn't have to use this capability in this situation). So I'd guess that even with significant IR experience it is very difficult if not impossible to maintain a steady spiral in a cloud without proper instrumentation (like a turn indicator). &lt;/p&gt;&#xA;" OwnerUserId="14419" LastActivityDate="2016-04-11T12:15:35.663" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26822" PostTypeId="2" ParentId="26815" CreationDate="2016-04-11T14:30:48.967" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;http://www.airbus.com/aircraftfamilies/passengeraircraft/a350xwbfamily/commonality/&quot; rel=&quot;nofollow&quot;&gt;only reference&lt;/a&gt; regarding A350 I could find is: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A350 XWB is the first aircraft to &quot;wear sunglasses,&quot; referring to&#xA;  this jetliner’s distinctive cockpit windows.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Although from the inside, the view appears to be normal. It could probably be adjustable because on &lt;a href=&quot;http://airwaysnews.com/blog/2016/03/20/onboard-tams-inaugural-airbus-a350-xwb-flight-to-the-americas/&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt;, you can see normal transparent windows from outside. &lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-04-11T14:30:48.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26823" PostTypeId="1" AcceptedAnswerId="26825" CreationDate="2016-04-11T14:53:39.853" Score="18" ViewCount="5880" Body="&lt;p&gt;Wikipedia says that the control surfaces were locked. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does this mean, and if the control surfaces cannot be moved, how did the aircraft get into the air in the first place?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="5517" LastEditDate="2016-04-11T15:32:31.223" LastActivityDate="2018-08-29T18:37:48.953" Title="Why did the first Boeing B17 test flight crash on takeoff?" Tags="&lt;boeing&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26824" PostTypeId="2" ParentId="26823" CreationDate="2016-04-11T15:01:06.253" Score="10" Body="&lt;p&gt;If you follow through the links to the one on &lt;a href=&quot;https://en.wikipedia.org/wiki/Ployer_Peter_Hill&quot;&gt;Ployer Peter Hill&lt;/a&gt; the B-17 (Model 299) test pilot, it says this about his death:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On October 30, 1935, Ployer Peter Hill died as a result of injuries received from the crash of the Boeing experimental aircraft Model 299 at Wright Field. &lt;strong&gt;The crash occurred because the crew neglected to remove the devices intended to keep the control surfaces from moving when the plane was on the ground.&lt;/strong&gt; This aircraft was the prototype of what would later become the famous B-17 Flying Fortress of World War II. Major Hill was buried in Newburyport, Massachusetts, on November 3, 1935.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically they forgot to remove the gust-lock devices. Yet another case for doing a thorough pre-flight check and control check before taking off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find any evidence or anything to suggest the aircraft ever left the ground, however its possible for the aircraft to become airborne just through the amount of lift generated at higher speeds. Many airplanes will fly even with slight nose-down attitudes. Its also possible that the gust locks still allowed enough elevator movement to get off the ground. The link that &lt;a href=&quot;http://www.thisdayinaviation.com/30-october-1935/&quot;&gt;Federico provided&lt;/a&gt; seems to suggest that the elevator was in the up position and allowed the aircraft to climb into a stall, but still not completely clear since most tail-draggers require some down-elevator to get the tail up, then up elevator to climb.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-11T15:06:59.270" LastActivityDate="2016-04-11T15:06:59.270" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26825" PostTypeId="2" ParentId="26823" CreationDate="2016-04-11T15:37:19.757" Score="15" Body="&lt;p&gt;The prototype aircraft had small &quot;blocks&quot; (more like wedges) which were used to prevent the control surfaces moving in the wind and potentially damaging the control surfaces, or even moving the aircraft on the ground. A bit like putting chocks under the wheels to stop the aircraft rolling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These were not removed when the aircraft was taken on a test flight, so the control surfaces could not move. Essentially, they were &quot;fixed&quot; in an approximately neutral position. Imagine if you couldn't move your steering wheel in your car because someone had put wedges next to your front wheels to prevent them turning: that's basically the situation the pilots were dealing with, but unlike you they can't just hit the brakes and stop once the aircraft is in the air.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;The Boeing 299 / B-17 are &quot;taildragger&quot; aircraft.&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As you can see in &lt;a href=&quot;http://fly.historicwings.com/wp-content/uploads/2012/10/HighFlight-Checklist4.jpg&quot; rel=&quot;noreferrer&quot;&gt;this photograph&lt;/a&gt; which I won't link directly due to the size, the aircraft's nose is pointing quite sharply &quot;up&quot; when on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a B-17, which isn't identical to the Type 299 but is close enough that it makes no difference. Hopefully this gives you the visual to see why the aircraft will lift off at a high enough speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mdQj2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mdQj2.jpg&quot; alt=&quot;B-17&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When accelerating the nose being pointed slightly up gives a positive angle of attack for the wings. This means that once the aircraft gets above stall speed, it will naturally lift off into the air. Essentially, the aircraft is already pitched slightly up before any control surfaces are moved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That also means that when the aircraft takes off, it will climb - at least initially. With the locked elevators, there is no way to change the pitch angle of the aircraft, and the aircraft will either pitch up or down naturally - there is almost no chance that the aircraft would be perfectly trimmed by accident.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case, the position the elevators were locked caused the aircraft to continue pitching up until it stalled. The crew had no way to correct this and the aircraft stalled out, rolled and crashed into the ground.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastEditorUserId="3945" LastEditDate="2016-04-11T16:08:16.487" LastActivityDate="2016-04-11T16:08:16.487" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="26826" PostTypeId="1" AcceptedAnswerId="26827" CreationDate="2016-04-11T15:44:56.647" Score="28" ViewCount="11374" Body="&lt;p&gt;At 4:30 in this YouTube video, a Chinook traverses the runway on its rear wheels. The text on the video lists &quot;Emergency landing and take-off&quot;. Is there any reason for the pilot to do this other than &quot;because I can and it's an airshow&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/9pBHB7tYceg?start=270&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot then proceeds to back down the runway on the rear wheels, a maneuver that I can only imagine is showing off, but again, is there a legitimate flying need to do this?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="15311" LastEditDate="2018-01-02T12:38:54.350" LastActivityDate="2018-01-02T12:38:54.350" Title="What would the reason be for this helicopter maneuver?" Tags="&lt;landing&gt;&lt;helicopter&gt;&lt;ch-47&gt;" AnswerCount="5" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26827" PostTypeId="2" ParentId="26826" CreationDate="2016-04-11T17:20:44.167" Score="50" Body="&lt;p&gt;Ex-Royal Air Force helicopter force here, spent a lot of time around Chinooks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the main answer is &quot;because I can&quot;, but I can think of a legitimate combat use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are heavy, and forced to land downwind into a narrow strip because there is a hazard on the upwind side of the landing zone.  There is not enough room to turn around.  You could hover taxi backwards like this to pick up some inflow into the rotors from the relative airflow (and therefore increased lift), then climb away backwards until you do have enough room to transition into normal forward flight, more or less as shown in the video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is where team work kicks in - you've &lt;strong&gt;really&lt;/strong&gt; got to trust your load master who is telling you exactly where you are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never seen it done though.&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2016-04-11T17:20:44.167" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26828" PostTypeId="1" CreationDate="2016-04-11T19:41:21.253" Score="3" ViewCount="16077" Body="&lt;p&gt;Yesterday, the Department of Energy was flying a military helicopter at low altitudes over Boston and the surrounding area &lt;a href=&quot;http://nnsa.energy.gov/mediaroom/pressreleases/nnsa-conduct-aerial-radiation-assessment-survey-over-boston-area-0&quot; rel=&quot;nofollow noreferrer&quot;&gt;as part of an experiment of some type to measure radiation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I saw one of these aircraft when I driving through Watertown and in fact it passed right over me. It was operating at a very dangerous altitude. Any kind of engine failure would have created a multiple fatality situation. Normally, aircraft do not fly at high speed below 500 feet and when helicopters descend below 500 feet they normally do so cautiously and in an area they know to be safe. Having a large helicopter flying at high speed over a dense city at 100 feet AGL is very dangerous and against FAA regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The type of helicopter was not the civvy type pictured in the news story, it was a Chinook. For NASA to be circulating a photo with a little civvy helicopter and then actually flying around a big Chinook I thought was pretty deceptive on their part. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have not filed a pilot complaint about this because I assume some kind of special &quot;permission&quot; or exception was created to allow for this dangerous activity. Does anybody know the legal authority involved here and conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BTW, I did not check the NOTAMs and did not get any NOTAMs in my mailbox on this, so if somebody can link the NOTAM that would be useful.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Update:&lt;/strong&gt; this may have been a medevac flight, with emphasis on the word &quot;may&quot;. Apparently, in some cases military helicopters are used for medevac flights to Burlington. However, if it was, the pilot was hot dogging and off the normal routes, both of which are serious regulation violations, but nevertheless I am told some military pilots disregard the rules.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="15311" LastEditDate="2017-12-27T13:34:18.497" LastActivityDate="2020-03-05T18:13:16.833" Title="Under what conditions would a helicopter be allowed to fly at low altitude over populated areas?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;helicopter&gt;&lt;notam&gt;&lt;regulations&gt;" AnswerCount="3" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26829" PostTypeId="2" ParentId="26826" CreationDate="2016-04-11T19:55:46.790" Score="5" Body="&lt;p&gt;It looks like it's done to showcase the impressive level of skill &amp;amp; control that the pilot is able to achieve w/ this aircraft. Sort of like the Ken Block Gymkhana video series, where he's showing off amazing car control, but you would never want to drive like that except in a drifting contest.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stretching the definition of 'practical', if you needed to tow something a short way &amp;amp; you had no pickup truck available, but somehow you did have a Chinook helicopter w/ a world-class pilot.... this would &lt;em&gt;kind of be an option&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: I just enjoyed the mental image of someone using a Chinook as a pickup truck&lt;/p&gt;&#xA;" OwnerUserId="14424" LastActivityDate="2016-04-11T19:55:46.790" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26832" PostTypeId="2" ParentId="26828" CreationDate="2016-04-11T21:26:22.697" Score="9" Body="&lt;p&gt;I have no idea about the specific flight you saw, but the general answer to your question about operating legally below the minimum safe altitudes in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:2.0.1.3.10.2.4.10&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.119&lt;/a&gt; is that the FAA can grant a waiver allowing lower flight. The &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.3,Ch7,Sec1&quot; rel=&quot;nofollow noreferrer&quot;&gt;waiver process&lt;/a&gt; says that to get a waiver to 91.119(b) (flight over congested areas) there must be a public interest reason but aircraft can't be lower than 500ft unless lives are at stake:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When issuing the waiver, the altitude requested should be an absolute&#xA;  minimum, but may not be less than 500 feet from persons or property,&#xA;  unless necessary to safeguard human life&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There isn't enough information about the helicopter you saw to say what was going on but assuming that it really was a Chinook at at 100' AGL then it was too low even for a waiver, according to the FAA's process. But the most obvious explanation is simply that it was taking off; helicopters take off in a &lt;a href=&quot;https://aviation.stackexchange.com/a/23222/62&quot;&gt;range of attitudes and airspeeds&lt;/a&gt; and some of those takeoffs are probably relatively low and fast. It might have been a medevac flight (they're often brightly painted) or perhaps something to do with logistics or construction; if you got the N number then you could look it up.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-11T21:26:22.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26833" PostTypeId="1" AcceptedAnswerId="26843" CreationDate="2016-04-11T21:39:18.683" Score="8" ViewCount="1250" Body="&lt;p&gt;I was wondering, the publicly announced departure time of a commercial flight, is it the ETOT (estimated takeoff time) or is it the &lt;a href=&quot;http://www.eurocontrol.int/lexicon/lexicon/en/index.php/Estimated_Off-Block_Time&quot;&gt;EOBT&lt;/a&gt; (estimated off-block time)? Or maybe some other time?&lt;/p&gt;&#xA;" OwnerUserId="878" LastEditorUserId="878" LastEditDate="2016-04-11T23:38:55.397" LastActivityDate="2016-04-12T10:53:00.763" Title="Which one is considered the departure time of a commercial flight?" Tags="&lt;commercial-aviation&gt;&lt;time&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26834" PostTypeId="2" ParentId="26790" CreationDate="2016-04-11T21:41:43.220" Score="5" Body="&lt;p&gt;After watching the video the problem he was having was in keeping it horizontal. It appears that the software isn't able to control the unpowered motors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know absolutely nothing about quads but I'm assuming with a fixed rotor pitch they must use variable voltage to the motor to control everything such as translational movement. I'm also assuming they have an accelerometer to determine pitch. The first question is how accurate the accelerometer is at low g's. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, when in free fall if a rheostat that is controlled by the computer could be connected across the sides of the motor then your problem could be solved. The freewheeling motors will create a voltage just like a generator so a rheostat would be able to control the current and thus the mechanical resistance to the motor. The rheostat will have an inverse relationship with the mechanical resistance (more electrical resistance less mechanical resistance). How linear that relationship is you'll have to experiment with. If you have the software switch to controlling that resistance it should be able to direct the freefall in the same way it does everything under power, only it will be more limited In its authority. If you do it right you might even be able to use the power generated to recover a little bit of the energy from the fall to charge the batteries like a hybrid car does. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like I said, I know absolutely zero about quadecopters so I can't fill in any details, but it seems feasible.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-04-11T21:41:43.220" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26836" PostTypeId="2" ParentId="25633" CreationDate="2016-04-11T22:34:56.197" Score="0" Body="&lt;p&gt;As already mentioned, airspace capacity is not a simple term. One very important aspect is aircraft separation. For example in procedural control separation is time based and (if I recall) it's 10 minutes flight time. That's definitely less capacity when compared to 10 miles for en-route and 6 for approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One other important aspect for calculating the capacity of a sector is the workload. Workload includes the time a controller spends talking (and listenign) to aircraft, coordinating flights, how much time is left for thinking and resolving conflicts etc. Eurocontrol has developed the CAPAN (capacity analyzer) methodology for calculating capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each sector is unique and has a unique capacity which the ANSP managing the sector should calculate. There is no &quot;one size fits all&quot; solution.&lt;/p&gt;&#xA;" OwnerUserId="878" LastActivityDate="2016-04-11T22:34:56.197" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26837" PostTypeId="2" ParentId="26808" CreationDate="2016-04-11T23:16:08.003" Score="9" Body="&lt;p&gt;I'm offering this answer more for amusement to readers than anything;&#xA;everything is factual first-person observation by me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No.  I cannot fly a glider in a cloud on primary instruments.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I was a young man of 23 years old I flew hang gliders before I obtained my Private Pilot's license in the USA about 1986. My flight instruments in my hang glider were an aircraft altimeter with 20 foot resolution, a variometer that was sensitive to about 50 foot per minute climb/descent rate, and very sensitive airspeed indication by human ear.  I lacked any turn or bank or artificial horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my flying club it was common knowledge that intentionally flying into a cloud like a cumulonimbus was tantamount to suicide.  This was about 1986 and already there were a number of reports of hang-glider's deaths from hypoxia and hypothermia from thermallinig up into cumulonimbus clouds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once in a competition flying from Crested Butte Colorado USA I was in such a strong thermal that it took me over one minute to exit a thermal and I luckily did exit it at 17000 feet MSL.  Imagine this; usually glider pilots seek lift.  In this case I identified it was dangerous and dove a straight line to exit the thermal and just escaped zero visibility within the cloud deck of 17000 feet MSL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My total flight time that day was 4 hours and 20 minutes with a maximum altitude of 17,000 feet above sea level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my years in the flying club I knew of one individual that fought  being lifted into a cumulonimbus cloud by performing wing-over maneuvers which is an easy way to waste energy meaning to waste altitude.  He eventually broke the spar of his hang-glider with excessive G forces, then spiraled like a maple seed under his busted glider and saved himself at lower altitudes with his emergency parachute.  He's the only hang-glider friend I know to have deployed a parachute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I hope this was fun to read.  Comments or questions are welcome.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastEditorUserId="13424" LastEditDate="2016-04-12T00:20:51.240" LastActivityDate="2016-04-12T00:20:51.240" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26838" PostTypeId="2" ParentId="26532" CreationDate="2016-04-11T23:41:25.303" Score="0" Body="&lt;p&gt;There is no requirement for a blunt leading edge. Some low speed subsonic airfoils, such as the Wainfan Facetmobile, have sharp leading edges. Airfoil design has a lot of tradeoffs, lift/drag, predictable stall characteristics, etc.&lt;/p&gt;&#xA;" OwnerUserId="14426" LastActivityDate="2016-04-11T23:41:25.303" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26839" PostTypeId="2" ParentId="26532" CreationDate="2016-04-12T00:18:17.367" Score="5" Body="&lt;p&gt;The short answer is that a blunt leading edge tolerates a wider envelope of angle of attack than a sharp leading edge.  Making it even simpler to understand it makes the airplane more forgiving to fly than a sharp leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm certain someone will give a more thorough explanation consistent with what I have said here.  I just thought it would be useful to give a quick reply.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-04-12T00:18:17.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26840" PostTypeId="2" ParentId="26826" CreationDate="2016-04-12T00:54:12.703" Score="27" Body="&lt;p&gt;What you are seeing is whats called a &lt;a href=&quot;http://www.airspacemag.com/daily-planet/coming-extractions-46921426/?no-ist&quot;&gt;Pinnacle Landing or Pinnacle Maneuver&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why its practiced is much cleared from the below image. The Chinook has a large base that may prevent it from safely landing in circumstance that require an evacuation from a small raised area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NhB8Y.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NhB8Y.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user14257" LastActivityDate="2016-04-12T00:54:12.703" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26841" PostTypeId="2" ParentId="15194" CreationDate="2016-04-12T03:10:48.230" Score="0" Body="&lt;p&gt;It is not correct that on most aircraft including the newest Boeing, Dassault, bombardier products only display indicated Mach. You do need to check your manuals.  Only the Gulfsteam aircraft display true Mach.  &lt;/p&gt;&#xA;" OwnerUserId="14427" LastActivityDate="2016-04-12T03:10:48.230" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26842" PostTypeId="2" ParentId="13957" CreationDate="2016-04-12T03:45:35.180" Score="-3" Body="&lt;p&gt;There are actually two sources of induced drag (see &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift-induced_drag&quot; rel=&quot;nofollow&quot;&gt;wikipedia article&lt;/a&gt;.  One source is described well by Peter's post. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the other source is vortex drag, from the wingtip vortices (turbulence), which depend on the aspect ratio of the wing as well as on wingtip treatments like winglets.   In the end the wingtip vortices lower the glide ratio (L/D) of the aircraft.  So if they produce a little bit of lift, it doesn't help because the drag has increased by a bigger factor, lowering the L/D. &lt;/p&gt;&#xA;" OwnerUserId="14428" LastEditorUserId="14428" LastEditDate="2016-04-12T05:10:37.877" LastActivityDate="2016-04-12T05:10:37.877" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26843" PostTypeId="2" ParentId="26833" CreationDate="2016-04-12T04:47:32.680" Score="6" Body="&lt;p&gt;The scheduled time is the EOBT. Flights that depart within 15 minutes of it are considered on-time.&#xA;Standard taxi times for each airport are included in the scheduled flight time.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-04-12T04:47:32.680" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26844" PostTypeId="1" AcceptedAnswerId="26845" CreationDate="2016-04-12T06:11:41.833" Score="5" ViewCount="938" Body="&lt;p&gt;I thought that the actuators are hydraulically controlled when the hydraulic fluid changes their position, but some aircraft (Bombardier, for example) has hydraulically powered and electrically controlled actuators.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;What does electrically controlled means?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How does hydraulics power the actuator?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="1467" LastEditDate="2016-04-12T07:22:19.980" LastActivityDate="2016-04-12T13:06:32.577" Title="What are hydraulically powered and electrically controlled actuators?" Tags="&lt;flight-controls&gt;&lt;electrical-system&gt;&lt;control-surfaces&gt;&lt;bombardier&gt;&lt;hydraulic-system&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26845" PostTypeId="2" ParentId="26844" CreationDate="2016-04-12T07:04:11.557" Score="5" Body="&lt;p&gt;As &lt;a href=&quot;https://en.wikipedia.org/wiki/Electro-hydraulic_actuator&quot; rel=&quot;nofollow noreferrer&quot;&gt;wikipedia&lt;/a&gt; mentions, &quot;Electro-Hydrostatic actuators&quot; (EHA) are self contained, the only input they need is electrical power and commands.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electricity powers up the hydraulic pump that is used to move the actuator piston, while the electrical commands are used to select what the actuator does through the use of a valve.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;What does electrically controlled means?&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Means that the position (and thus the action) of the valve is controlled via a solenoid. The following scheme shows a valve with two solenoids. The valve has three positions, indicated by the three squares. Depending on the electrical control signal, the current in the solenoids changes and thus moves the selector (the block with the three squares) laterally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/E2avm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E2avm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.sukanmarketing.com/blog/hydraulic/cnc-repair-and-troubleshooting-hydraulic-solenoid-valves-and-simple-circuit-diagram&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;How does hydraulics power the actuator?&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Through a pump. Where the fluid goes is selected by the electrically controled valve, but the piston of the actuator is moved by the hydraulic fluid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the image below, if the valve of the image above is in the central position, the actuator does not move.&#xA;If it is in the left position, the actuator retracts.&#xA;If it is in the right position (with the two arrows crossing) the actuator extends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WqGZ5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WqGZ5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.sukanmarketing.com/blog/hydraulic/cnc-repair-and-troubleshooting-hydraulic-solenoid-valves-and-simple-circuit-diagram&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-04-12T13:06:32.577" LastActivityDate="2016-04-12T13:06:32.577" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26846" PostTypeId="1" AcceptedAnswerId="26850" CreationDate="2016-04-12T07:13:41.163" Score="12" ViewCount="1116" Body="&lt;p&gt;I'm sitting in a small regional airport in Vietnam and I've noticed something odd about the aircraft I've seen arriving and departing. All of these aircraft appear to have the copilot-side window covered or shaded. (The windows are covered from the inside with what looks like the reflective covers you put against your car windshield if you park in the sun to keep the inside of your car from heating up so badly.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these aircraft are ATR 72's, and they're all flown by the same airline. The one I just observed depart had the copilot's side window and cockpit window covered at the time they taxiied to the runway. The one I just saw land had just the side window covered when it taxiied off of the runway and over to the &quot;gate.&quot; I can't speak to whether the window was still covered when the plane actually took off since I didn't have a clear view from the airport of the actual runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(What I'm calling &quot;copilot-side&quot; is the left-hand side if you're standing in front of and looking towards the tail.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of keeping some of the cockpit windows covered? Is it a regular practice? (Is it safe? It seems like a safety hazard to cut your visibility in half while taxiing around an airport, even if this place is just an airstrip.)&lt;/p&gt;&#xA;" OwnerUserId="373" LastActivityDate="2016-04-12T12:56:10.320" Title="Why would a copilot's window be shaded/covered?" Tags="&lt;commercial-aviation&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26847" PostTypeId="2" ParentId="26833" CreationDate="2016-04-12T10:45:49.493" Score="-1" Body="&lt;p&gt;In &lt;a href=&quot;http://www.euro-cdm.org/library/airports/cdg/data_sheet_nr3.pdf&quot; rel=&quot;nofollow&quot;&gt;this document&lt;/a&gt; you will find some of the many timestamps used in CDM.&#xA;As you can see there, the EOBT is the timestamp displayed in the flight plan.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The time on the ticket usually corresponds to the ETA/ETD which in term should be STOT (scheduled take-off time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are you extracting information from a data source or are you just curious?&lt;/p&gt;&#xA;" OwnerUserId="5588" LastEditorUserId="878" LastEditDate="2016-04-12T10:53:00.763" LastActivityDate="2016-04-12T10:53:00.763" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26848" PostTypeId="1" CreationDate="2016-04-12T12:01:41.853" Score="19" ViewCount="4648" Body="&lt;p&gt;Are there any airports with scheduled services where big jets (say 737 or A320) or wide bodies regularly operate without control tower? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any rules (EASA FAA) for this? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If controllers go on strike can commercial air transport continue to operate?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastEditorUserId="5517" LastEditDate="2016-04-12T12:51:23.430" LastActivityDate="2016-08-19T14:49:20.520" Title="Can commercial air traffic operate from uncontrolled airport, airspace?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;airline-operations&gt;&lt;easa-regulations&gt;" AnswerCount="5" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26849" PostTypeId="2" ParentId="26848" CreationDate="2016-04-12T12:21:19.370" Score="15" Body="&lt;p&gt;I will answer your question with what we can see in Brazilian Airspace and its rules.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Brazil, there are some airports - non towered, operated by radio stations - which give information such as wind direction/intensity and temperature and QNH. Based on this information, the pilot decides on which runway they will land or take off, and relays this message to the radio operator. The operator will only relay these pieces of information to pilots monitoring the radio frequency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those airports are not controlled, then, if there is any strike, flying visually, no control will be effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, &lt;a href=&quot;https://en.wikipedia.org/wiki/Ara%C3%A7atuba_Airport&quot;&gt;ARU/SBAU&lt;/a&gt; is a non towered airport, and &lt;a href=&quot;https://en.wikipedia.org/wiki/TAM_Airlines&quot;&gt;TAM Airlines&lt;/a&gt; operates the A320F there.&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="6886" LastEditDate="2016-04-12T18:59:28.997" LastActivityDate="2016-04-12T18:59:28.997" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26850" PostTypeId="2" ParentId="26846" CreationDate="2016-04-12T12:48:16.990" Score="16" Body="&lt;p&gt;Aircraft flight decks can become very warm at times and pilots will always try their best to avoid letting the sun add any additional heat. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most aircraft have sun visors or sun screens as part of the flight deck equipment. These are usually a clip-on design or pull-shade design. Both types are translucent and can be left in place for all phases of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many pilots will also bring their own temporary sun shades to use in the flight deck. Theses can be translucent or opaque. Many pilots even use their charts as temporary make-shift shades while parked at a gate in the blaring sun. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you described them as reflective covers, I suspect what you saw may have been some kind of temporary shade supplied by the company. They would not be used on the forward windscreen so they would be safe to use during taxiing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some examples of a pull shade being used in an ATR 72.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Rt0em.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rt0em.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/KS7UY.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KS7UY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WTPRU.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WTPRU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example of what looks like a reflective shade.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/edMZJ.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/edMZJ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-12T12:56:10.320" LastActivityDate="2016-04-12T12:56:10.320" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26851" PostTypeId="1" AcceptedAnswerId="26855" CreationDate="2016-04-12T13:15:15.437" Score="2" ViewCount="376" Body="&lt;p&gt;Depending on the types of de-ice and anti-ice fluids used, the HOT changes.&#xA;Is it possible to post some HOT table here?&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="19" LastEditDate="2016-06-28T16:16:24.177" LastActivityDate="2016-06-28T16:16:24.177" Title="Is there a source of deicing holdover time tables?" Tags="&lt;ground-operations&gt;&lt;deice&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26852" PostTypeId="2" ParentId="26848" CreationDate="2016-04-12T13:18:41.530" Score="15" Body="&lt;p&gt;The Canadian Arctic has B737 scheduled airline operations to many uncontrolled airports that have no control tower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wz0Is.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wz0Is.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yVjbr.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yVjbr.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-12T13:18:41.530" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26853" PostTypeId="2" ParentId="26851" CreationDate="2016-04-12T13:22:26.190" Score="0" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/media/FAA_2015-16_HoldoverTables.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;This FAA document&lt;/a&gt; has a lot of them, starting on page 11.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One example, from &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/publications/tp185-4-08-operations-4049.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Transport Canada&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ibW7p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ibW7p.jpg&quot; alt=&quot;Type 4 holdover time graphic&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-04-12T13:37:38.627" LastActivityDate="2016-04-12T13:37:38.627" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26854" PostTypeId="2" ParentId="26848" CreationDate="2016-04-12T13:26:17.817" Score="12" Body="&lt;p&gt;American Airlines &lt;a href=&quot;https://flightaware.com/live/flight/AAL363/history/20160402/1645Z/KDFW/KGUC&quot; rel=&quot;nofollow noreferrer&quot;&gt;operates an A319&lt;/a&gt; seasonally from DFW to &lt;a href=&quot;https://www.aa.com/i18n/travelInformation/destinationInformation/gunnison/gunnison.jsp&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gunnison&lt;/a&gt; (KGUC), which &lt;a href=&quot;http://airnav.com/airport/KGUC&quot; rel=&quot;nofollow noreferrer&quot;&gt;is an uncontrolled airport&lt;/a&gt;. There are probably many other similar examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airline flight arriving at an uncontrolled field operates just like any other aircraft: it will almost certainly be IFR and fly an instrument approach, or a visual approach if conditions allow it. Radio calls, pattern etc. should be the same as for any other aircraft arriving IFR at an uncontrolled airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airline's &lt;a href=&quot;https://aviation.stackexchange.com/q/1641/62&quot;&gt;OpSpec&lt;/a&gt; might have some specific procedures for uncontrolled airports, but otherwise it's just another aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers going on strike is a totally different scenario; you might want to ask about that separately.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-12T13:26:17.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26855" PostTypeId="2" ParentId="26851" CreationDate="2016-04-12T13:35:36.793" Score="3" Body="&lt;p&gt;Here are some holdover charts I have access to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UTf0X.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UTf0X.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;&lt;a href=&quot;https://i.stack.imgur.com/cWpOV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cWpOV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ifewa.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ifewa.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/M2R6l.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M2R6l.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/mxtYR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mxtYR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6T5dh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6T5dh.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0FZKk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0FZKk.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/nF5wm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nF5wm.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/dUgFn.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dUgFn.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-12T14:16:13.380" LastActivityDate="2016-04-12T14:16:13.380" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26856" PostTypeId="1" CreationDate="2016-04-12T13:39:51.347" Score="7" ViewCount="557" Body="&lt;p&gt;Are there any statistics on the distribution of pilots between the two genders? Specifically, has the ratio changed over the past decades (I'd expect female pilots to be getting more common)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware that the number will vary between countries. I'm more interested in the trend of certain group(s) that are statistically significant to an area (e.g. all commercial carriers in the United Kingdom / all PPL holders in the United States).&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-04-12T13:50:25.730" LastActivityDate="2016-04-12T16:29:34.373" Title="What is the trend of gender distribution among pilots?" Tags="&lt;pilots&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26857" PostTypeId="2" ParentId="26856" CreationDate="2016-04-12T13:41:56.650" Score="7" Body="&lt;p&gt;At least for the FAA, you can get the &lt;a href=&quot;https://www.faa.gov/data_research/aviation_data_statistics/civil_airmen_statistics/&quot; rel=&quot;noreferrer&quot;&gt;U.S. Civil Airmen Statistics&lt;/a&gt; as a download that covers from 2005 to 2014. It includes data based on gender and license type. I'm not sure when they will update for 2015. If you download the 2010 one, it has data back to 2001, so about 13 years of data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an example of the data provided:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dV6VV.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dV6VV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly for the UK, you can download statistics from &lt;a href=&quot;https://www.caa.co.uk/Data-and-analysis/Approved-persons-and-organisations/Datasets/&quot; rel=&quot;noreferrer&quot;&gt;this website&lt;/a&gt;. I haven't downloaded them but it looks like what you are looking for is there.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may be able to find similar data for Canada, Australia, and some other relatively &quot;open&quot; countries. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-12T14:03:45.837" LastActivityDate="2016-04-12T14:03:45.837" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26858" PostTypeId="2" ParentId="26856" CreationDate="2016-04-12T14:26:09.057" Score="5" Body="&lt;p&gt;Air Canada's pilots are about 95% male and that is about average for all North American airlines.   The Air Line Pilots Association, which represents pilots in Canada and the U.S., recently reported that 5.4 per cent of members are women. British Airways said in 2013 that 200 of its 3,500 pilots are women – about 5.7 per cent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air Canada's first female pilot was hired in 1978 and recently retired after 37 years.  &lt;a href=&quot;http://www.ctvnews.ca/canada/as-air-canada-s-first-female-pilot-retires-95-per-cent-are-still-men-1.2390777&quot; rel=&quot;noreferrer&quot;&gt;Air Canada's first female pilot retires, 95 per cent are still men&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-12T14:26:09.057" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26859" PostTypeId="1" AcceptedAnswerId="26863" CreationDate="2016-04-12T16:18:34.707" Score="32" ViewCount="5696" Body="&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm a model aviation enthusiast and really enjoy seeing how far people can push the limits of aerobatics. Model aircraft are able to push the limits well beyond full scale due to their small size. I understand that this is only possible because models are small* so they can withstand forces that would kill any occupants in a manned craft. Also, model aircraft are typically overpowered when compared to full scale aircraft&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, I don't have a model plane that isn't capable of a 30 degree climb, and it's quite common for aerobatic model airplanes to have thrust to weight ratios exceeding 1.5:1 or even 2:1. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I first saw some of what &lt;a href=&quot;https://youtu.be/Qrmd_Qdryos?t=235&quot;&gt;model helicopters were capable of&lt;/a&gt; I was blown away. Having also seen some full scale helicopter aerobatics (&lt;a href=&quot;https://www.youtube.com/watch?v=uYbx5H5e9Es&quot;&gt;Red Bull Demonstration&lt;/a&gt;) I've been wondering just what full scale helicopters are capable of. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the Red Bull Demonstration it looked like the helicopter might use some negative (or at least neutral) collective while rolling, however it did not appear that it would have enough to sustain an inverted hover or inverted flight. This got me wondering: has there been a full scale helicopter capable of sustaining inverted flight or an inverted hover (which takes even more power)? If there hasn't, would it be possible to purpose build a helicopter that would be capable of doing so? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Note&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm just wondering about technical possibility of creating a machine capable of this maneuver. For the scope of this question, please ignore the regulatory, legal, and economical obstacles that would need to be overcome to attempt such a feat (not to mention finding a pilot willing to try).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, I'm only asking about full scale inverted flight. I understand physics get in the way very fast if someone were to try to design a full scale helicopter capable of all the aerobatics models do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*some model airplanes and helicopters can be greater than 35% full scale, but that is still small when compared to full scale aircraft.&lt;/p&gt;&#xA;" OwnerUserId="14435" LastEditorUserId="22726" LastEditDate="2018-10-16T03:00:04.513" LastActivityDate="2018-10-16T03:00:04.513" Title="Are there full scale helicopters capable of sustaining inverted flight?" Tags="&lt;helicopter&gt;&lt;aerobatics&gt;&lt;inverted-flight&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26860" PostTypeId="2" ParentId="26848" CreationDate="2016-04-12T16:26:11.670" Score="8" Body="&lt;p&gt;Any plane can land at any airport as long as the runway is long enough. There is no regulation saying that a 737 cannot land at a non-controlled airport. All of the commercial pilots that have had their training in the private sector have had to land at non controlled airports. I say all, but I'm sure there are some exceptions. Let's just say most. It is no big deal. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here at our local airport, KLBX, there is no tower and there are four large jets that come and go every single day, even when the weather is IFR. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is so little realistic understanding of aircraft and air travel due to the continued misrepresentation by the media and movies.  There was the incident of the control tower guy falling asleep and the commercial flight had to land without the tower control. It was all over the news as though it was a miracle that the plane didn't just crash all over the place. As though a pilot cannot land a plane without the tower saying &quot;Cleared to land 13R.&quot; That's all they do anyway. The pilot is still responsible for looking and seeing if the runway is really clear and ready to take the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In IFR conditions there is still what's called the minimums. If you can't see the runway when you reach the minimums you are not allowed to land there. Again, there is an exception, but it won't be available at non-controlled airports because of the cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know about Brazil or Japan or any other country. I fly in the US only, and most of it in Texas. You'd be surprised how many non-towered airports there are where you even have to turn on the runway lights from your plane at night.&lt;/p&gt;&#xA;" OwnerUserId="8228" LastEditorUserId="995" LastEditDate="2016-04-12T19:02:19.857" LastActivityDate="2016-04-12T19:02:19.857" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26862" PostTypeId="1" AcceptedAnswerId="26873" CreationDate="2016-04-12T17:01:55.693" Score="6" ViewCount="1368" Body="&lt;p&gt;Source: Wolfgang Langewiesche - Stick and Rudder; An Explanation of the Art of Flying&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the first chapter the author mentions, in a glide, if you want to descend more steeply, you want to want to point your nose less steeply.&#xA;And if you want descend less steeply you point your nose more steeply. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the reason for this?&lt;a href=&quot;https://i.stack.imgur.com/gVmwO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gVmwO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2016-04-12T22:02:09.870" Title="What does this statement about steep descent mean?" Tags="&lt;descent&gt;&lt;nose&gt;" AnswerCount="4" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26863" PostTypeId="2" ParentId="26859" CreationDate="2016-04-12T17:08:49.040" Score="34" Body="&lt;p&gt;There is no real helicopter capable of sustained inverted flight and certainly not of hovering inverted.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The simple reason is that there is no operational need to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it theoretically possible?  Yes, but you have a lot of engineering problems to overcome.  In addition to inverted fuel and oil systems, the rotor head will be much more complex than it needs to be.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When flying normally, the fuselage effectively hangs like a pendulum underneath the rotor with a large nut (OK, it's more complex than that) holding the rotor onto the rotor shaft hub.  The rotor pulls the fuselage up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To fly inverted, the rotor must be able to push the fuselage up so the hub would have to be engineered to apply and withstand the appropriate forces in both directions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then, the rotating blade cuffs, and associated hinges, must be designed so that the blades can have negative pitch (as seen from the normal attitude) across the full range.  In turn, this means that the collective mechanism must be designed so that it is possible to set positive and negative pitch as required.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades would also need to be more rigid, so that they do not cone excessively and contact the fuselage.  This would add more forces to the head joints which would need to be strengthened.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, you must &quot;reverse&quot; the cyclic controls so that the expected collective pressure, cyclic back; nose up; reduce speed; works in the opposite sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've probably not considered other factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of this would add significant complexity and weight which, given that there is no requirement for inverted flight, will not happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, the power required to fly or hover inverted would be the same as for normal flight.  There is no intrinsic reason why inverted flight would need more power - blades rotating at a certain speed, with a particular angle of attack will generate the same amount of lift no matter which way they are pointing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason model helicopters can do this is that the ratio of the weight of the rotor to the weight of the fuselage is much lower than for a real helicopter, and therefore requires a lot less power to produce the required lift, and models have a much higher power to weight ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason real helicopters can go inverted for a short time in aerobatic manoeuvres is because the momentum on the fuselage is pulling away from the rotor so that the lift vector pointing up, toward the fuselage, is countered. Consider an outside loop, which would be impossible, since the momentum of the fuselage and the lift vector would combine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should be able to demonstrate this in a model with a normally designed rigid head.  Add some (secure) ballast in the fuselage until you must accelerate in ground effect to gain translational lift in order to be able to climb out.  Now try to fly inverted!&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-04-13T06:01:15.170" LastActivityDate="2016-04-13T06:01:15.170" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="26864" PostTypeId="2" ParentId="26862" CreationDate="2016-04-12T17:11:43.830" Score="0" Body="&lt;p&gt;This is apparently talking about maneuver around the best glide speed. The behavior of an airplane is counter-intuitive then. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pushing the nose down, increases the speed and causes the angle of descent to decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pulling the nose up, decreases the speed and causes the angle of descent to increase.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastEditorUserId="595" LastEditDate="2016-04-12T17:13:21.807" LastActivityDate="2016-04-12T17:13:21.807" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26865" PostTypeId="2" ParentId="26862" CreationDate="2016-04-12T17:51:03.247" Score="6" Body="&lt;p&gt;That comment by Wolfgang Langewiesche in his book &quot;Stick and Rudder&quot; has caused lots of discussion over the years. Maybe that is what he intended when he worded it so ambiguously.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;By pointing the nose down less steeply, you descend more steeply. By pointing the nose down more steeply, you can glide further&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is really only true if you are flying just a little bit slower than best glide speed (best Lift /Drag ratio) or (best glide distance).  Also, that statement is really only true if you point the nose up or down just a little. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best glide distance means the speed at which the most distance is traveled for the least amount of sink. If you are flying slower than the best glide speed, putting the nose down and going faster, so that you are closer to the best glide speed, will allow you to cover more distance as the aircraft sinks. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are already flying at the best glide speed and point the nose down, you will no longer be at the beast lift to drag ratio. You will increase the speed and distance traveled, but you will also increase the sink rate and drag from the higher airspeed. That will result in a steeper descent because you are no longer at the best lift to drag ratio.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you point the nose down to 60 degrees below the horizon I guarantee you will descend more steeply not less steeply and NOT glide farther as Langewiesche says in the book. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-12T22:02:09.870" LastActivityDate="2016-04-12T22:02:09.870" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26866" PostTypeId="1" CreationDate="2016-04-12T18:25:36.967" Score="0" ViewCount="1134" Body="&lt;p&gt;Irrespective of the stall speed, the only reason aircraft stalls is when its control surface (elevator, aileron) exceeds critical AOA. Then what is the significance of the stall speed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Does the aircraft stall at the &quot;stall speed&quot; even if its AOA is less than critical?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="4108" LastEditDate="2016-04-12T19:35:12.020" LastActivityDate="2016-04-12T19:35:12.020" Title="What is the significance of stall speed" Tags="&lt;stall&gt;&lt;angle-of-attack&gt;" AnswerCount="2" CommentCount="4" ClosedDate="2016-04-12T20:39:56.553" ContentLicense="CC BY-SA 3.0" />
  <row Id="26867" PostTypeId="2" ParentId="808" CreationDate="2016-04-12T18:30:56.597" Score="2" Body="&lt;p&gt;In conventional forums (i.e. in person), the FAA even organizes interactions with controllers. Here is an example of a Pilot-Controller forum for Livermore Airport, in Northern California, organised by the &lt;a href=&quot;https://www.faasafety.gov/&quot; rel=&quot;nofollow&quot;&gt;FAASTeam&lt;/a&gt; team.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faasafety.gov/SPANS/event_details.aspx?eid=47646&quot; rel=&quot;nofollow&quot;&gt;https://www.faasafety.gov/SPANS/event_details.aspx?eid=47646&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A search for the term &quot;controller&quot; indicates that such interactions are common: &lt;a href=&quot;https://www.faasafety.gov/SPANS/events/EventList.aspx&quot; rel=&quot;nofollow&quot;&gt;https://www.faasafety.gov/SPANS/events/EventList.aspx&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen similar presentations involving controllers which are web-based, and which are followed by Q&amp;amp;A sessions with participants.&lt;/p&gt;&#xA;" OwnerUserId="995" LastActivityDate="2016-04-12T18:30:56.597" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26868" PostTypeId="1" CreationDate="2016-04-12T18:32:25.653" Score="0" ViewCount="42" Body="&lt;p&gt;Can anyone tell me which pilot training institute is best for getting CPL in India?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What other things are needed to be done along with CPL in order to become a co-pilot in an airliner?&lt;/p&gt;&#xA;" OwnerUserId="14441" LastEditorUserId="14441" LastEditDate="2016-04-12T18:36:38.800" LastActivityDate="2016-04-12T18:36:38.800" Title="Guidance on becoming a pilot" Tags="&lt;flight-school&gt;&lt;cpl&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-04-12T19:10:04.750" ContentLicense="CC BY-SA 3.0" />
  <row Id="26869" PostTypeId="2" ParentId="26866" CreationDate="2016-04-12T18:56:04.313" Score="0" Body="&lt;p&gt;No. If the angle of attack is not critical, then it does not matter what the relative air speed is, the plane will not stall. By definition the &quot;critical&quot; AOA is the angle the plane stalls at, so you are asking sort of a tautological question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stall speed is there for guidance only, to give the pilot a general idea of at about what point the aircraft will begin to stall in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice the speed at which the aircraft actually stalls will vary according to a lot of different conditions such as temperature, humidity, angle of bank, gust conditions and many other factors, even how clean the wings are.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-12T18:56:04.313" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26870" PostTypeId="2" ParentId="26862" CreationDate="2016-04-12T19:06:52.883" Score="2" Body="&lt;p&gt;The key thing here is that he is referring to the ANGLE of descent, not the RATE of descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you push the stick forwards the rate of descent will always increase, but the angle of descent may actually decrease. This is because you go faster so you generate more lift, thus your overall angle of descent will decrease.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A typical beginner's mistake some glider pilots make is that they get worried they are not descending fast enough when they are landing so they push the stick forwards to dive--a big mistake. What happens is they go a lot faster, so they tend to overshoot even more. Pulling back on the stick, slowing the aircraft down and flattening the pitch is what to do to steepen the angle of descent, just as Langewiesche says.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-12T19:06:52.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26871" PostTypeId="2" ParentId="26866" CreationDate="2016-04-12T19:16:37.110" Score="2" Body="&lt;p&gt;There is not one stall speed, instead &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=93d736bfb443106e1d2faa4523edcca0&amp;amp;mc=true&amp;amp;node=se14.1.23_149&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;there are several&lt;/a&gt;, depending on aircraft configuration and flight conditions. They are used to determine speeds for the safe operation of the aircraft or for limit speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example: The stall speed in landing configuration and level flight with the actual weight is used for determining the approach speed. By multiplying with a safety factor of 1.3, you arrive at the recommended approach speed. Or: The stall speed in take-off configuration is used for determining the rotation speed. And so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example: The speed range in which it must be &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=93d736bfb443106e1d2faa4523edcca0&amp;amp;mc=true&amp;amp;node=se14.1.23_1345&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;safe to deploy flaps&lt;/a&gt; is limited by 1.4 times stall speed of the clean aircraft, or 1.8 times the stall speed in landing configuration, whichever is greater. Or: The &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=93d736bfb443106e1d2faa4523edcca0&amp;amp;mc=true&amp;amp;node=se14.1.23_1335&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;maneuvering speed&lt;/a&gt; v$_A$ is calculated by multiplying the stall speed of the clean aircraft with the square root of the maximum allowable load factor. And so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you wonder what a stall is, maybe it helps to read the &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed&quot;&gt;answers to this question&lt;/a&gt;. It is not flow separation or exceeding a specific angle on the control surfaces that determines the stall condition, but the reversal of the lift curve slope over angle of attack: Stall is when more angle of attack will no longer increase lift, so it is the angle of attack of the whole aircraft that counts. Physically, this means that large-scale flow separation appears over part of the wing. A good design will still have fully working control surfaces at this point.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-12T19:16:37.110" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26872" PostTypeId="2" ParentId="26848" CreationDate="2016-04-12T19:16:57.583" Score="6" Body="&lt;p&gt;Usually any airport with enough traffic that it would attract a big commercial jet will merit a tower. However, there are a few weird exceptions here and there and some of the other answers have described these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think you may be thinking that a tower would be necessary somehow or that flying a heavy into an airport without a tower would be dangerous, and that is not necessarily true.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots can self-organize and land themselves just fine without a tower. The tower is mostly there to speed things up and enable large volumes of aircraft to land as quickly as possible. If an airfield is busy and there is no tower, then the aircraft will tend to spread themselves out more, approach from longer distances and do things more slowly. With the tower there it speeds everything up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airport is out in the middle of nowhere and does not get any traffic, then there is no need for a tower and it does not really matter whether the plane is big or small.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-12T19:16:57.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26873" PostTypeId="2" ParentId="26862" CreationDate="2016-04-12T20:01:44.103" Score="9" Body="&lt;p&gt;The statement is only true if you fly at a speed below the best glide speed. For simplicity, let's look at a glider: Below you see the plot of the L/D ratio over speed of the &lt;a href=&quot;https://en.wikipedia.org/wiki/DG_Flugzeugbau_DG-1000&quot; rel=&quot;nofollow noreferrer&quot;&gt;DG-1000 two-seater glider&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/DUyHv.jpg&quot; alt=&quot;Glide ratio over speed diagram&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Glide ratio over speed diagram for three different wing loadings (&lt;a href=&quot;https://aviation.stackexchange.com/questions/606/why-would-a-glider-have-water-ballast-if-it-is-trying-to-stay-aloft-without-an/698#comment6823_609&quot;&gt;source&lt;/a&gt;). If we just look at the lowest wing loading (leftmost curve), the best L/D can be achieved when flying at 95 km/h. Minimum speed is around 62 km/h, so it is entirely possible to fly along at 80 km/h. When the pilot reduces the angle of attack, the aircraft will pitch down and speed up. If it now flies at 90 km/h, he has just improved his L/D from 43 to 46, so he will descend less steeply when dropping the nose. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that our flight path angle is now less steep, and the change in attitude is less than the commanded change in angle of attack. Nevertheless, the pitch attitude is reduced and the pilot has the impression that he dropped the nose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same is true in reverse when slowing down. When approaching the stall speed, large angle of attack changes will result in relatively small speed changes, so the effect of a steeper descent when pitching up becomes more pronounced as the airplane slows down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The underlying reason is the fact that &lt;a href=&quot;https://aviation.stackexchange.com/questions/3670/is-the-maximum-lift-drag-ratio-found-at-minimum-drag/3674#3674&quot;&gt;drag will increase when the pilot moves away from the best L/D speed&lt;/a&gt;. Slowing down will increase drag, and more drag will result in a steeper descent. As soon as he shifts his starting point to higher speeds, things reverse and the aircraft will descend more steeply when the nose is lowered.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adding an engine will not fundamentally change this behavior. It is only easier to explain when using gliders.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-04-12T20:01:44.103" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26875" PostTypeId="2" ParentId="26826" CreationDate="2016-04-12T22:03:39.573" Score="1" Body="&lt;p&gt;My guess is that if you need to get into and out of a 'hot' strip this approach would minimise the time (and position in the sky) that you would be exposed to enemy fire. Just the sort of flying that might be needed on special ops.&lt;/p&gt;&#xA;" OwnerUserId="14445" LastActivityDate="2016-04-12T22:03:39.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26876" PostTypeId="1" AcceptedAnswerId="26879" CreationDate="2016-04-12T23:58:01.367" Score="5" ViewCount="830" Body="&lt;p&gt;This is about the &lt;a href=&quot;https://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision&quot; rel=&quot;nofollow&quot;&gt;crash over Lake Constanz/Überlingen&lt;/a&gt; on July 1, 2002. The planes were on a collision course, the automated TCAS told one to climb and the other to descend, but air traffic control gave the opposite order to the Russian plane and they crashed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, why were they on a collision course? I have not seen anything indicating they were off course. Don't planes flying different directions fly at different altitudes? And aren't there paths in the sky that planes are supposed to stay in? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about flight plans? Does anyone check to see if two planes are on a collision course?&lt;/p&gt;&#xA;" OwnerUserId="14447" LastEditorUserId="22726" LastEditDate="2019-02-21T04:29:16.197" LastActivityDate="2019-02-21T04:29:16.197" Title="Why were DHL611 and Bashkirian 2937 on a collision course?" Tags="&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;accidents&gt;&lt;mid-air-collision&gt;" AnswerCount="2" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26877" PostTypeId="2" ParentId="26876" CreationDate="2016-04-13T01:25:04.897" Score="2" Body="&lt;p&gt;Aircraft flying in different directions fly at same altitudes (FLs) &lt;em&gt;at different times&lt;/em&gt;. If two aircraft were to to be found in the same FL at the same time, the ATC would assign different FL to atleast one of them, so as to minimize the risk.&lt;/p&gt;&#xA;&lt;p&gt;In this case, the controller didn't notice that the two aircraft were in the same FL due to various reasons (mainly, he was concentrating on a delayed A320). From the &lt;a href=&quot;http://www.bfu-web.de/EN/Publications/Investigation%20Report/2002/Report_02_AX001-1-2_Ueberlingen_Report.pdf?__blob=publicationFile&quot; rel=&quot;nofollow noreferrer&quot;&gt;accident investigation report&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When the TU154M crew contacted Zurich at 21:30:11 hrs for the first time and also reported the flight level, the controller did not notice that the B757-200 had reached the same flight level and that both airplanes were approaching each other at right angles. The distance between the two aircraft was still approximately 64NM. If he had noticed the situtation, he would have instructed the TU154M crew to descend to FL350.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The investigation listed this among the immediate causes of the accident:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The following immediate causes have been identified:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The imminent seperation infringement was not noticed by ATC in time. The instruction for the TU154M to descend was given at a time when the prescribed seperation to the B757-200 could not be ensured anymore.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-18T14:15:30.883" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26878" PostTypeId="1" CreationDate="2016-04-13T02:02:14.827" Score="1" ViewCount="90" Body="&lt;p&gt;How can an aircraft still continue to fly when it turns turtle or upside down in air? Is'nt it opposite of 'lift' principle?&lt;/p&gt;&#xA;" OwnerUserId="14436" LastEditorUserId="3201" LastEditDate="2016-04-13T06:27:03.440" LastActivityDate="2016-04-13T06:27:03.440" Title="Isn't lift inverted when flying upside down?" Tags="&lt;aerodynamics&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-04-13T04:27:15.187" ContentLicense="CC BY-SA 3.0" />
  <row Id="26879" PostTypeId="2" ParentId="26876" CreationDate="2016-04-13T02:03:32.133" Score="14" Body="&lt;p&gt;The Airways that the planes fly on criss-cross the sky and there are many, many intersections where there can be a potential for 2 aircraft to meet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, it is normal that aircraft are routinely flight planned to be on &quot;collision courses&quot;. The flight plans don't keep aircraft separated. They are used so that Air Traffic Controllers can know the exact routing and plan where any conflicts may occur. It is normal and safe as ATC can then keep the aircraft separated using radar.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally aircraft flying eastbound fly at odd altitudes and westbound aircraft fly at even altitudes. This works quite well but we can still have 2 westbound aircraft both flying at 36,000' on a &quot;collision course&quot; because westbound can mean any track from 180 degrees to 359 degrees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case the 2 aircraft were crossing paths at about 90 degrees to each other at the same altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally they would be constantly monitored and the ATC controller would simply have one aircraft climb or descend to avoid the other aircraft. Another common practice is to tell one aircraft to turn slightly off course to avoid the other aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On this day the ATC system and the controller were both overloaded and a number of factors contributed to the controller not seeing the conflict until it was almost too late. At the last minute he told one aircraft to descend to avoid the other. This action alone would have been fine but the order was given far too late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Traffic Collision Avoidance System on the aircraft also saw the conflict and automatically issued an instruction for one pilot to climb while instructing the other aircraft to descend.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The controller did not know that the TCAS had also spotted the conflict and his  command to descend was contrary to the TCAS climb command. The pilot chose to follow the controller's instruction instead of following the TCAS climb instruction. The other aircraft was also following his TCAS instruction to descend so both aircraft were now descending while still on a conflicting flight path routing.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS is there as a safeguard when the ATC system fails. It should always take priority over an ATC instruction.  It is clear that the ATC system failed these pilots and TCAS operated as it should. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As pilots we spend so much time following ATC instructions that I can see how it would be difficult to ignore the controller and instead follow the TCAS instruction. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-13T02:18:27.717" LastActivityDate="2016-04-13T02:18:27.717" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26880" PostTypeId="1" CreationDate="2016-04-13T05:10:00.703" Score="9" ViewCount="2334" Body="&lt;p&gt;Just curious. Would it do nothing, would it generate a massive amount of thrust? Would it even work?&lt;/p&gt;&#xA;" OwnerUserId="13120" LastActivityDate="2016-04-18T14:13:02.633" Title="What would happen if put a jet engine behind another jet engine?" Tags="&lt;jet-engine&gt;" AnswerCount="4" CommentCount="12" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26881" PostTypeId="2" ParentId="26880" CreationDate="2016-04-13T06:23:03.967" Score="7" Body="&lt;p&gt;Engines need &lt;strong&gt;oxygen&lt;/strong&gt; for fuel combustion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turbojet&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After most of the oxygen has been extracted and used to oxidize / burn fuel in the first engine, air is no more useful. In the second engine the core combustion wouldn't start, air would just turn the discs, but there would be no compression, so no additional thrust (discs would actually slow the flow).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Afterburners try to burn the remaining oxygen after the core combustion, but there is only the previously mentioned limited quantity to burn. An afterburner is not a second engine, it has no rotating parts, only burners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turbofan&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition of the core flow, a turbofan has a bypass flow. The bypass flow is not used for combustion and still contains its oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However this flow generates most of the thrust by air compression / acceleration, so anything which slows the cold flow also degrades the engine efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a technique to burn the bypass flow: The &lt;a href=&quot;https://en.wikipedia.org/wiki/Plenum_chamber&quot;&gt;plenum chamber&lt;/a&gt;, but this requires something different and no rotors are involved.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-04-13T07:55:43.237" LastActivityDate="2016-04-13T07:55:43.237" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26883" PostTypeId="1" CreationDate="2016-04-13T06:53:10.920" Score="24" ViewCount="9317" Body="&lt;p&gt;Most commercial jet engines today would be those large jet engines on large passenger craft like a Boeing 747. Can these run on &lt;strong&gt;straight ethanol&lt;/strong&gt; without any problems?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would more maintenance be required? Would the engine lifetime be reduced? Would it be more susceptible to flameouts or other mechanical risks? Would the airplane never make it off the ground? (I imagine thrust reduction will be limit the takeoff weight.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One reason I'm asking is because eventually petrol will be gone. (I'm not an apocalyptic saying that will happen next year, but somewhere down the line it will certainly be gone.) Will jet engines require a major redesign, or could they just use ethanol for a few years/decades and be fine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: I'm talking about &lt;strong&gt;jet engines (turbofans, but turbojets are okay too)&lt;/strong&gt;, but &lt;strong&gt;not&lt;/strong&gt; piston engines and turboprops.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; A lot of talk has been generated that ethanol contains less energy than kerosene. &lt;strong&gt;I assure you I'm aware of this.&lt;/strong&gt; Ethanol is like 25 MJ/kg and kerosene is more like 40 or 45. I'm not asking this question with energy efficiencies in mind, but rather out of curiosity if the same engine geometries will work well with both fuels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;A rephrasing:&lt;/strong&gt; Would current jet engine geometries (blade angles, compression ratios, volumetric flow, etc.) work well with ethanol instead of regular jet fuel?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="17971" LastEditDate="2018-01-17T23:22:36.783" LastActivityDate="2020-02-20T00:45:57.533" Title="Could most commercial jet engines today run on ethanol without any problems?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;&lt;fuel&gt;" AnswerCount="7" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26885" PostTypeId="2" ParentId="17203" CreationDate="2016-04-13T06:58:23.443" Score="2" Body="&lt;p&gt;Theoretically it is possible to make a pivot turn on a B777, according to the Flight Crew Training Manual (FCTM) from Boeing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a turn is started after lining up with the edge of the runway, stopping the aircraft completely,locking the brakes on the inner side of the turn and applying thrust to the outer engine on the turn. The wheels on the inner side of the turn will be really locked and subject to a high stress, and there is potential for tyre and runway surface damage. Such a turn on a B777-300 would require a minimum runway width of 43.6 meters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a procedure that involves ground crew coordination and supervision and quite a risk both for the personnel involved, the landing gear and tyres and the runway surface, so it is not a normal manoeuvre, probably used only in an emergency situation where no other option is available. Having a tug to manoeuvre the aircraft around could be a much better option.&lt;/p&gt;&#xA;" OwnerUserId="14455" LastEditorUserId="3386" LastEditDate="2016-04-13T07:12:20.870" LastActivityDate="2016-04-13T07:12:20.870" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26886" PostTypeId="2" ParentId="26754" CreationDate="2016-04-13T07:22:55.787" Score="2" Body="&lt;p&gt;MTRs are used for all types of military training at low altitude.  Low altitude flying in the military is typically defined as below 5k AGL although certain systems such as terrain following can be defined slightly differently. Flying below 5k AGL with tactical maneuvering (formation, practicing weapons deliveries, or using a system like terrain following) involves a different level of focus and training than above 5k. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your example when bringing a brand new pilot and teaching him how to trust and when not to trust the terrain following system at night at 500' and 500kts, flat is the perfect training environment. Later on I would take a student in the mountains and further build confidence in the system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best thing to know as a GA pilot is that the military is flying fast and often doing high-G maneuvering at low altitude so it's best to stay 5nm either side of one of these routes and fly above it by around 3-5k AGL or the limits of the original route.&lt;/p&gt;&#xA;" OwnerUserId="14451" LastEditorUserId="1467" LastEditDate="2016-04-13T07:29:08.787" LastActivityDate="2016-04-13T07:29:08.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26887" PostTypeId="2" ParentId="26883" CreationDate="2016-04-13T07:48:35.920" Score="10" Body="&lt;p&gt;Yes, jet/turbine engines can run on ethanol... but ethanol has only 60% of the energy content per mass unit of Jet-A fuel which means you have to use 67% more of it by mass to get the same energy output. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll have to increase the additional fuel carried (due to having to lug around a lot more low density fuel) of every aircraft by quite a margin if you were to fuel them with ethanol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternative energy use for turbine engines has been studied extensively.  The problem is always that they pack much less energy density than Jet-A, making them unfeasible.&lt;/p&gt;&#xA;" OwnerUserId="3399" LastActivityDate="2016-04-13T07:48:35.920" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26888" PostTypeId="2" ParentId="26883" CreationDate="2016-04-13T08:08:07.083" Score="38" Body="&lt;p&gt;Although turbines could be designed to run on ethanol it's actually a lousy aviation fuel (actually it's a lousy fuel in general). Petroleum-based jet fuel is high grade kerosene which has lubricant properties, which ethanol lacks, and ethanol has different characteristics which mean you can't pour it in and use it as a replacement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some problems with ethanol as a fuel are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;It's a solvent which dissolves some types of seals and hoses&lt;/li&gt;&#xA;&lt;li&gt;It evaporates very easily, and can cause vapor lock&lt;/li&gt;&#xA;&lt;li&gt;It is &lt;a href=&quot;https://en.wikipedia.org/wiki/Hygroscopy&quot; rel=&quot;noreferrer&quot;&gt;hygroscopic&lt;/a&gt;, meaning it attracts and mixes with water very readily. Water contamination would not settle to the lowest point, instead it would be suspended with the fuel&lt;/li&gt;&#xA;&lt;li&gt;It has significantly less stored energy per unit of weight. Jet fuel has an energy density of 46&amp;nbsp;MJ/kg (megajoules per kilogram) and pure ethanol has 26.4&amp;nbsp;MJ/kg; that's only 57% of the energy density of jet fuel! Even if a jet was able to burn it at its maximum efficiency it would get just over half the oomph from it.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;There are bio-fuel replacements for jet (and diesel) fuels based on oilseed crops like rapeseed (&lt;a href=&quot;https://en.wikipedia.org/wiki/Canola&quot; rel=&quot;noreferrer&quot;&gt;canola&lt;/a&gt;), palm oil, etc. These are processed to remove their OH atoms using &lt;a href=&quot;https://en.wikipedia.org/wiki/Transesterification#Methanolysis_and_biodiesel_production&quot; rel=&quot;noreferrer&quot;&gt;transesterification&lt;/a&gt; to create fuels which are almost identical chemically. Modifying jets to use ethanol would be hugely expensive if it is even possible to do, so there's no point given there's a suitable replacement. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The point is actually moot though because crop-based biofuels are never going to replace petroleum. There simply aren't enough crops grown to feed people and engines at the same time, in fact even if we used all the worlds farmable land to grow bio-fuel crops instead of food crops we still would not have enough of it to replace fossil fuels. We have enough trouble feeding people already and the biofuels craze is not helping that. Bio-fuels based on non-food crops from marginal land may some day become economically viable and partially replace petroleum fuels.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After some searching I found a link to &lt;a href=&quot;http://www.iaopa.eu/mediaServlet/storage/gamag/aug08/GA_p24-25.pdf&quot; rel=&quot;noreferrer&quot;&gt;an article&lt;/a&gt; I wrote on biofuels for AOPA UK magazine which goes into more detail on biofuel issues. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2016-04-14T07:38:14.367" LastActivityDate="2016-04-14T07:38:14.367" CommentCount="19" ContentLicense="CC BY-SA 3.0" />
  <row Id="26889" PostTypeId="2" ParentId="26883" CreationDate="2016-04-13T08:53:40.757" Score="7" Body="&lt;p&gt;I'm not an expert of real jet engines. I think it should in general be possible to run a jet on ethanol, though some modification might be necessary. Some materials might not be resistant to ethanol and need replacement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the main reason for not using ethanol is that it contains by far less energy: Just 27MJ per kilogram instead of 43MJ for jet fuel.&#xA;For the same energy demand (i.e. an entire flight), the aircraft would need 60% more fuel, plus additional fuel to carry the additional fuel...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is some data about the A380 from &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot;&gt;wikipedia&lt;/a&gt; (fuel weight calculated by a factor of 0.8kg/l):&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Maximum take-off weight    575,000 kg (1,268,000 lb)&#xA;Operating empty weight     276,800 kg (610,200 lb)&#xA;Max. fuel capacity         256,000 kg (564,000 lb) (44% MTOW)&#xA;-------------------------------------------------------------&#xA;Calculated payload:        299,000 kg&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;If the aircraft would use ethanol, this changes to:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Maximum take-off weight    575,000 kg (1,268,000 lb)&#xA;Operating empty weight     276,800 kg (610,200 lb)&#xA;ethanol equivalent:        407,000 kg (900,000 lb) (70% MTOW)&#xA;-------------------------------------------------------------&#xA;Calculated payload:       -108,000 kg (-240,000 lb)&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Even if you manage to load the additional fuel, the aircraft is waaay to heavy to take off, even without payload.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;It's not the cost (or availability), it's the bad energy density which makes ethanol unsuitable.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It would be better to use something more similar to jet fuel like Biodiesel, which is similar to fossile diesel. Biofuels typically also have a lower energy density, but not to an extent that it makes them technically unsuitable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are different kinds of such fuels for aviation, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Aviation_biofuel&quot;&gt;wikipedia has an impressive list&lt;/a&gt; of test and commercial flights using biofuels. In most cases, a mixture of fossile fuel and biofuel was used, but on some flights, one engine (or the entire aircraft?) was powered by pure biofuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main problem with biofuel of any kind still is availability. We simply can't produce enough to replace fossile fuels completely. &lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2016-04-13T08:53:40.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26890" PostTypeId="2" ParentId="26880" CreationDate="2016-04-13T12:19:41.403" Score="12" Body="&lt;p&gt;There is an alternate way to answer your question, and it relates to thermodynamics.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think about the purpose of a jet engine.  It exists to take uncompressed air, compress it, mix it with fuel, burn it efficiently and then expand it (hopefully adiabatically) to generate a larger volume of gas at higher pressure than the intake.  The work done by the engine is described by the Brayton cycle (Figure 3.13 from &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node28.html&quot; rel=&quot;noreferrer&quot;&gt;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node28.html&lt;/a&gt;), and this cycle shows us where we can and can't hope to achieve theoretically efficient operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at the chart of the cycle in the above reference, you'll note that the compression and exhaustion portions of the cycle are where inefficiency (in the form of entropy) creep in and prevent the cycle from being perfect.  As such, even if there were sufficient oxygen left to burn, putting two jet engines back to back would be horribly inefficient (because you are repeating the inefficient portions of each twice).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The better solution is to work towards improving compression ratios, and recovering more work from expansion.  Much of this has been done over the last 50 years, and is why Brayton efficiencies are in the 0.6 to 0.7 range for modern jet engines (ref same website, Figure 3.19).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: Also, remember that jet engines are designed to work on air that is &quot;cold&quot; relative to their exhaust. They don't compress hot gases efficiently. You could certainly design a compressor to efficiently compress hot gases for combustion, but jet engine compressor sections are not designed for this, so the compression achieved by the second engine in your question would be MUCH lower than its design, which would further decrease it's contribution of additional thrust. &lt;/p&gt;&#xA;" OwnerUserId="14322" LastEditorUserId="14322" LastEditDate="2016-04-15T00:05:46.450" LastActivityDate="2016-04-15T00:05:46.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26891" PostTypeId="2" ParentId="22232" CreationDate="2016-04-13T15:10:42.540" Score="2" Body="&lt;p&gt;I thought of another one; if you're installing wingtips and it doesn't matter whether they point up or down, the latter will be less of an obstruction to the view from the cockpit, which is convenient for an aircraft also used for forward observation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's an interesting question! I think my answer wasn't mentioned yet?&lt;/p&gt;&#xA;" OwnerUserId="14458" LastActivityDate="2016-04-13T15:10:42.540" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26892" PostTypeId="2" ParentId="26532" CreationDate="2016-04-13T15:19:46.857" Score="11" Body="&lt;p&gt;When using an airfoil with a sharp leading edge in subsonic regime, you need to &lt;strong&gt;adapt&lt;/strong&gt; the angle of attack so that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stagnation_point&quot; rel=&quot;noreferrer&quot;&gt;stagnation point&lt;/a&gt; occurs right on the sharp edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At every flight condition there should be an AoA which achieves this. Higher AoA, and the stagnation point is too low. To low AoA, and the stagnation point is too high. However flight conditions change frequently, so the required AoA changes dynamically as well. Since AoA also drives the lift and lift is the priority in a pilot's mind (he wants to keep flying after all), stagnation point will only &lt;em&gt;occasionally&lt;/em&gt; match the leading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During flight &lt;strong&gt;the AoA will often fail to match the stagnation point&lt;/strong&gt;, let's say with too high AoA, separation would occur below the leading edge (on the &quot;intrados&quot;).  This is the only good illustration I could find:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4jPp4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4jPp4.jpg&quot; alt=&quot;Reverse flow and stagnation point&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stagnation point is at the tip of the only grey line that stops right on the black plate.&#xA;Basically all incoming flow between these leading edge and stagnation point  (unfortunately no line shows this on the picture) will follow this trajectory:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Incoming at high speed onto the airfoil, below leading edge, going towards the stagnation point, but aims just slightly higher up.&lt;/li&gt;&#xA;&lt;li&gt;The stagnation point is the point of highest pressure, so the incoming flow slows down&lt;/li&gt;&#xA;&lt;li&gt;Comes a point where the slowdown is sufficient to actually reverse the flow which now shoots up along the surface towards the leading edge, now driven by the pressure from stagnation point&lt;/li&gt;&#xA;&lt;li&gt;Arriving at the leading edge from below the flow needs to do a U-turn around the leading edge to keep following the wing shape and flow towards the &quot;extrados&quot; and keep on with its life.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Therein lies the problem: when finally arriving at the leading edge, the air has non-zero speed (zero speed only occurs at stagnation point, of which there is only one), but must instantly reverse it. Physics says &lt;strong&gt;nope&lt;/strong&gt;, and you get a large leading edge vortex to smooth the motion out. Unfortunately that is also called a flow separation bubble, which may became a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;bad for performance (drag)&lt;/li&gt;&#xA;&lt;li&gt;bad for safety (stallable)&lt;/li&gt;&#xA;&lt;li&gt;bad for comfort (vibration from the eddies) &lt;/li&gt;&#xA;&lt;li&gt;bad for structure (vibration fatigue)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why does it only happen in subsonic flight?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At supersonic speeds, information cannot travel back on the flow using the same pressure gradient trick, once the air is on the intrados/extrados, it stays there, and cannot back up the other way. So no 'adaptation' is possible, regardless of AoA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why use rounded leading edge to remedy this in subsonic?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With a rounded edge, the U-turn is not so sharp, it is actually manageable for the air. This means you'll not always have flow separation, so you're safe. The rounder, the easier larger the range of AoA stay &quot;adapted&quot;. This animated gif shows really well how the stagnation point can move around the rounded tip thus avoiding separation:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/orPr6.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/orPr6.gif&quot; alt=&quot;Stagnation point moving vs. AoA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;Source: UNIVERSITY OF GENOA&#xA;FACULTY OF ENGINEERING&#xA;DEPARTMENT OF ENVIRONMENTAL ENGINEERING&#xA;IRROTATIONAL PLANE FLOWS OF AN INVISCID FLUID&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TL;DR&lt;/strong&gt; It's possible to fly subsonic with sharp leading edge, but less safe and lower performance. The key is AoA adaptation.&lt;/p&gt;&#xA;" OwnerUserId="13917" LastEditorUserId="13917" LastEditDate="2018-09-19T15:57:44.353" LastActivityDate="2018-09-19T15:57:44.353" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26893" PostTypeId="2" ParentId="24498" CreationDate="2016-04-13T15:43:08.627" Score="6" Body="&lt;p&gt;While not used for commercial aircraft, many military aircraft used started cartridges. These were slow burning explosives much like black powder packed into a canister and installed in the side of the engine. When ignited they produced a relatively high speed exhaust that rotate the turbines to reach starting speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They were used regularly on alert B-52 and KC135 aircraft during the cold war. &lt;/p&gt;&#xA;" OwnerUserId="14459" LastActivityDate="2016-04-13T15:43:08.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26895" PostTypeId="2" ParentId="9822" CreationDate="2016-04-13T16:34:06.727" Score="4" Body="&lt;p&gt;&lt;strong&gt;The 1897 plane of Clement Ader has never left the ground&lt;/strong&gt;,  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;see: &lt;a href=&quot;http://wrightbrothers.altervista.org/Ader/1897/1897-10-27--Mensier--Report-Trials-Clement-Ader-Avion--Paris-Oct-21-27-1897.htm&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;General Mensier's Report&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Clement Ader did not fly. The October 21, 1897 report made by general MENSIER and its annex from October 27, 1897 (see the link) are clear, Ader’s plane never left the ground with its front wheels in both the October 12 and 14, 1897 officially witnessed tests. The October 14, 1897 alleged take off and short flight is a pure myth contradicted by historical documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was Clement Ader an aviation pioneer? Yes, because he built a plane in 1897. Was he a flyer? No. Did he fly earlier in 1890? No. The 1897 (Avion III) plane was seen on the ground by General Mensier and his comision. Other earlier planes (Avion I and II), Ader claimed he had built, has never been seen in the air or on the ground.&lt;/p&gt;&#xA;" OwnerUserId="10018" LastActivityDate="2016-04-13T16:34:06.727" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26898" PostTypeId="1" AcceptedAnswerId="26911" CreationDate="2016-04-13T19:20:11.053" Score="8" ViewCount="1653" Body="&lt;p&gt;There are some circles below the wings of these two aircraft. Look:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/j5GQd.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j5GQd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/KLM-Cityhopper/Embraer-190STD-%28ERJ-190-100STD%29/1593053/L/&amp;amp;sid=493e6194844e841ebffeb0bbaa95ebab&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt; (modified)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nPCqF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nPCqF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/China-Eastern-Airlines/Airbus-A320-214/1100601/L/&amp;amp;sid=640147ea93b37fb357990949f84d4e02&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the second picture the circles are clearly visible on the wing. What are they? What is their purpose?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2017-09-19T20:05:28.963" Title="What are these circles below the wing?" Tags="&lt;airliner&gt;&lt;wing&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26899" PostTypeId="2" ParentId="26898" CreationDate="2016-04-13T20:30:58.617" Score="3" Body="&lt;p&gt;These are inspection rings. From FAA Advisory Circular &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861&quot; rel=&quot;nofollow&quot;&gt;43.13-1B&lt;/a&gt; (complete &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_02.pdf&quot; rel=&quot;nofollow&quot;&gt;PDF is here&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Inspection Rings. Inspection access is provided adjacent to or over&#xA;  every control bellcrank, drag-wire junction, cable guide, pulley, wing&#xA;  fitting, or any other component throughout the aircraft which will be&#xA;  inspected or serviced annually. They are installed only on the bottom&#xA;  side of the wings except where installed on the top surface by the&#xA;  original manufacturer.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flighttraining.aopa.org/magazine/2016/January/feature-parts.html&quot; rel=&quot;nofollow&quot;&gt;This article&lt;/a&gt; also mentions it from a student's point of view.&lt;/p&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-04-13T20:30:58.617" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26900" PostTypeId="1" AcceptedAnswerId="26902" CreationDate="2016-04-13T21:23:52.997" Score="2" ViewCount="873" Body="&lt;p&gt;As far as I know, all engines used in aircraft produce thrust by means of some propellant: kerosene, hydrogen peroxide etc. Maybe I've missed something, but could you tell me, are there any engines that can produce thrust without using exhaust gases expelled from the nozzles? Is it even possible?&lt;/p&gt;&#xA;" OwnerUserId="14463" LastEditorUserId="13197" LastEditDate="2016-04-16T21:25:08.723" LastActivityDate="2020-05-04T20:13:33.973" Title="Is there any engine that doesn't use a propellant to produce thrust?" Tags="&lt;engine&gt;&lt;theory&gt;&lt;propulsion&gt;" AnswerCount="3" CommentCount="10" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26901" PostTypeId="2" ParentId="26880" CreationDate="2016-04-13T21:31:59.660" Score="3" Body="&lt;p&gt;You would end up with an extremely inefficient setup, if it works at all. It's not the lack of oxygen, because only 20-25% of the oxygen is begin burnt in the core jet engine, so there should be plenty of oxygen left for the second engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The high outlet temperature of the first engine would decrease the power of the second engine dramatically. The exhaust velocity of ENG1 would be reduced by ENG2 as it wouldn't be able to process the incoming volume of air. The turbulent flow will reduce the compressors efficiency as well. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All in all, there would be no benefit to such a setup at all.&lt;/p&gt;&#xA;" OwnerUserId="8771" LastActivityDate="2016-04-13T21:31:59.660" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26902" PostTypeId="2" ParentId="26900" CreationDate="2016-04-13T22:47:18.207" Score="6" Body="&lt;p&gt;No matter which kind of engine, you need &lt;em&gt;some&lt;/em&gt; way to supply the engine with energy and you need some way to store that energy until you need it in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short of going nuclear (and there are some nontrivial engineering problems involved in designing a halfway safe nuclear reactor that you can put on a plane and keep it lightweight enough that flying it isn't pointless), chemical fuels for burning have the best available ratios of weight to energy stored. This is particularly important for aviation because more weight means more induced drag which means more thrust needed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Joule for joule, the efficiency of fuel-burning engines is not great, but the superior energy density of hydrocarbon fuel more than makes up for that and allows them to supply more useful thrust per kilogram of energy storage lifted than either batteries (low losses, but very heavy) or fuel cells (medium losses, but require small-molecule fuel such as hydrogen or methane that still have markedly worse energy densities than kerosene).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Since you speak about &quot;exhaust gases&quot; in the question, note that current aircraft derive at most a small fraction of their thrust from ejecting &lt;em&gt;exhaust gases&lt;/em&gt;. Propeller planes don't generally make use of the exhaust at all, and &quot;jet&quot; engines are practically always &lt;em&gt;high-bypass turbofan&lt;/em&gt; engines where &lt;em&gt;most&lt;/em&gt; of the energy from the combustion goes to drive the fan that blows intake air backwards without burning anything in it.&lt;/p&gt;&#xA;" OwnerUserId="959" LastActivityDate="2016-04-13T22:47:18.207" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26906" PostTypeId="1" AcceptedAnswerId="26907" CreationDate="2016-04-14T04:20:59.543" Score="34" ViewCount="9579" Body="&lt;p&gt;Since we &lt;a href=&quot;https://aviation.stackexchange.com/questions/26848/can-commercial-air-traffic-operate-from-uncontrolled-airport-airspace&quot;&gt;don't need a control tower&lt;/a&gt; for instrument landings I was wondering what else that is thought to be needed could be skipped. I know some small general aviation is done on grass runways and I was wondering what is the biggest airplane that does not need a paved runway? Examples of manufacturer-approved usage or regular (e.g. daily or weekly) usage are preferred.&lt;/p&gt;&#xA;" OwnerUserId="2910" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-10-11T18:46:35.650" Title="What is the biggest airplane that does not need a paved runway?" Tags="&lt;aircraft-design&gt;&lt;runways&gt;&lt;aircraft-limitations&gt;" AnswerCount="6" CommentCount="13" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26907" PostTypeId="2" ParentId="26906" CreationDate="2016-04-14T04:55:11.250" Score="43" Body="&lt;p&gt;Military transports are designed to be operated from unpaved runways- by extension, any of these converted to civilian use can operate from unpaved runways. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_Airlines&quot;&gt;Antonov Airlines&lt;/a&gt; operates a number of &lt;a href=&quot;https://en.wikipedia.org/wiki/Antonov_An-124_Ruslan&quot;&gt;Antonov An-124 'Ruslan'&lt;/a&gt;, which can and do operate from unpaved runways regularly. The &lt;a href=&quot;http://www.volga-dnepr.com/en/fleet/an-124&quot;&gt;Volga-Dnepr group&lt;/a&gt; specifically states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Multi-leg landing gears equipped with 24 wheels allow to operate the aircraft on unpaved runways ...&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-14T04:55:11.250" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26908" PostTypeId="2" ParentId="26906" CreationDate="2016-04-14T05:36:19.123" Score="42" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Hughes_H-4_Hercules&quot; rel=&quot;noreferrer&quot;&gt;H-4 Hercules (Spruce Goose)&lt;/a&gt; should easily win this contest.  That plane was ridiculously huge and, in fact, couldn't use a runway, rather it was a &quot;flying boat&quot; that took off from the the water.  So I'd say it's the one...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted, if you mean a grass or gravel strip aeroalias is probably correct.  The only other major planes that I know were designed to land on gravel were the early &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;noreferrer&quot;&gt;737&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_727&quot; rel=&quot;noreferrer&quot;&gt;727&lt;/a&gt;.  They both had special landing gear guards that keeps the front gear from kicking gravel into the engines and both have specific instructions for preparing the landing gear for touch down on gravel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's the guard, if you were curious, on a 737:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3VwOv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3VwOv.jpg&quot; alt=&quot;737 nose gear with gravelkit guard&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;Source &lt;a href=&quot;https://www.flickr.com/photos/capnmikesphotos/14891693505&quot; rel=&quot;noreferrer&quot;&gt;https://www.flickr.com/photos/capnmikesphotos/14891693505&lt;/a&gt;, Author: Mike Pearson&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-04-15T16:08:44.617" LastActivityDate="2016-04-15T16:08:44.617" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26909" PostTypeId="2" ParentId="26883" CreationDate="2016-04-14T07:33:37.130" Score="0" Body="&lt;p&gt;NO!  Both as originally asked and revised.  NO!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintenance?  Jet-engines are LUBRICATED with their FUEL.  Ethanol does not have the necessary viscosity and lubricity to protect the moving surfaces.  How about replacement after every flight!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The High-bypass fan at the front of the engine requires a certain amount of Shaft Horse Power delivered from the “Jet” portion at the back.  The existing fuel lines can't deliver enough ethanol to achieve either full power or peak efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Burning ethanol will require re-engineering not limited to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;recirculating oil lubrication pumps&lt;/li&gt;&#xA;&lt;li&gt;oil coolers (which increase drag)&lt;/li&gt;&#xA;&lt;li&gt;larger fuel lines&lt;/li&gt;&#xA;&lt;li&gt;ethanol safe seals &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Ethanol's lower density alone does not prevent its use as the vast majority of commercial fights do not take off with full fuel and as such there has always been extra volume available.  However, the longest direct flights such as L.A. to Sydney will require a fuel stop.  Adding extra landings and takeoffs to an existing routes as well as fuel depots almost define the word problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ethanol?    NO!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Peanut oil? Yes&lt;/p&gt;&#xA;" OwnerUserId="14465" LastEditorUserId="5517" LastEditDate="2016-04-14T12:08:17.830" LastActivityDate="2016-04-14T12:08:17.830" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26910" PostTypeId="1" AcceptedAnswerId="26919" CreationDate="2016-04-14T10:26:46.557" Score="41" ViewCount="51311" Body="&lt;p&gt;I have looked at various questions on this SE site regarding this topic but I have not really found a satisfactory answer. Some comments &lt;a href=&quot;https://aviation.stackexchange.com/questions/9940/what-are-the-advantages-and-disadvantages-of-ducted-fans-in-designs-such-as-the/9949#comment19200_9949&quot;&gt;here&lt;/a&gt; regarding torque and power in electric motors vs gasoline engines were helpful. Additional info also found &lt;a href=&quot;https://aviation.stackexchange.com/questions/19569/how-many-kilowatts-to-get-an-electric-747-8-airborne&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Underlying my question is the assumption that battery technology will considerably advance from what is available commercially now. Simply assume that providing the electric motor with enough power is not an issue and that the weight of the battery is equal to fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Is it possible to build an electric aircraft engine that would allow current commercial airplanes the same capabilities as jet engines available today do?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="14468" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2020-05-30T15:06:05.417" Title="Could an electric engine provide the same performance as jet engines on current aircraft?" Tags="&lt;airliner&gt;&lt;electric-engine&gt;" AnswerCount="11" CommentCount="12" FavoriteCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="26911" PostTypeId="2" ParentId="26898" CreationDate="2016-04-14T11:01:21.597" Score="12" Body="&lt;p&gt;In the US, those are called either &quot;Access Panels&quot; or &quot;Inspection Covers&quot;, depending on their function, but many people combine the two terms and call them &quot;&lt;strong&gt;Inspection Panels&lt;/strong&gt;&quot;. Based on the comments, other parts of the world apparently refer to them as &quot;Inspection Ports&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We remove both panels and covers to perform routine inspections, but access panels cover system components that may be accessed more often for servicing. Both panels and covers are designed for quick removal, typically fastened with screws, as is the case in the aircraft depicted in the photos above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an inspection hole with the cover removed. This is on a Cessna 170 that I am in process of rigging. Note the aileron cable turnbuckle visible inside the wing. Through this access panel I will adjust the cable tension, among other things, and once the cable is properly tensioned I will safety wire this turnbuckle. Here the panel is removed for maintenance, but during an inspection I would remove this panel to inspect these same systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VD80x.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VD80x.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-09-19T20:05:28.963" LastActivityDate="2017-09-19T20:05:28.963" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26912" PostTypeId="2" ParentId="26910" CreationDate="2016-04-14T11:19:21.917" Score="13" Body="&lt;p&gt;Engines are great as they are. Electric engines can be fast, powerful and effective. I see two problems:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First - the sheer amount of energy consumed by the commercial airplane. With a single engine giving out 200kN you need a small power-plant attached to the aircraft. Even batteries would be 100% effective and could store enough energy, you need to burn higher amount of fuel to charge them up (you would need a A LOT of alternative energy sources to match the energy given out).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second - it is all about the energy density. Jet fuel having 34 MJ/l , batteries having up to 120 Wh/kg = 0.36MJ/kg (according to &lt;a href=&quot;http://www.epectec.com/batteries/cell-comparison.html&quot;&gt;this site&lt;/a&gt; ). So you need more than 100x more space to store the same amount of energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just search for the 'electric airplane' and you will get a list of mainly small, ultralight or self-propeled gliders where they don't need to carry a LOT of energy with it. &lt;/p&gt;&#xA;" OwnerUserId="14373" LastEditorUserId="14373" LastEditDate="2016-04-14T11:27:27.370" LastActivityDate="2016-04-14T11:27:27.370" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="26913" PostTypeId="1" AcceptedAnswerId="26915" CreationDate="2016-04-14T11:38:40.187" Score="11" ViewCount="1842" Body="&lt;p&gt;I'm in the process of writing a flight-dynamics software program, but I'm not sure what to call the derivatives of the aircraft attitude. If it was in one dimension, they would be the &quot;angular velocity&quot; and &quot;angular acceleration&quot; respectively.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In aviation, is there a special name for these vectors? &lt;/p&gt;&#xA;" OwnerUserId="13876" LastActivityDate="2019-10-16T21:46:05.947" Title="Is there a name for change in attitude with respect to time?" Tags="&lt;terminology&gt;&lt;attitude&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26914" PostTypeId="2" ParentId="26913" CreationDate="2016-04-14T11:46:52.130" Score="2" Body="&lt;p&gt;I believe you are looking for &lt;em&gt;yaw&lt;/em&gt;, &lt;em&gt;pitch&lt;/em&gt; and &lt;em&gt;roll&lt;/em&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Pitching for the nose moving up and down.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Yawing for the nose moving side to side.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Rolling for the wings rocking back and forth.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="609" LastActivityDate="2016-04-14T11:46:52.130" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26915" PostTypeId="2" ParentId="26913" CreationDate="2016-04-14T11:48:13.210" Score="22" Body="&lt;p&gt;The components of attitude vector are called:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;yaw (or heading) is the angle of longitudinal (&lt;em&gt;x&lt;/em&gt;) axis in horizontal plane,&lt;/li&gt;&#xA;&lt;li&gt;pitch is angle of longitudinal (&lt;em&gt;x&lt;/em&gt;) axis from the horizontal and&lt;/li&gt;&#xA;&lt;li&gt;roll is angle of lateral (&lt;em&gt;y&lt;/em&gt;) axis from the intersection of the &lt;em&gt;yz&lt;/em&gt; (orthogonal to longitudinal axis) plane with horizontal.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;And their derivatives are usually yaw-rate, pitch-rate and roll-rate. Second derivative names probably vary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding coordinate system, the first axis, called &lt;em&gt;x&lt;/em&gt;, is always longitudinal and positive direction is forward. The second axis, called &lt;em&gt;y&lt;/em&gt;, is usually lateral one, but positive direction is right in some systems and left in others. And &lt;em&gt;z&lt;/em&gt; completes a &lt;em&gt;right-handed&lt;/em&gt; coordinate system (so your vector products work the usual way), so &lt;em&gt;z&lt;/em&gt; down if &lt;em&gt;y&lt;/em&gt; points right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I thought &lt;em&gt;u,v,w&lt;/em&gt; is sometimes used as alias for the axis, but actually they are usually rather used for the velocity vector components.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-04-14T14:45:27.523" LastActivityDate="2016-04-14T14:45:27.523" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26916" PostTypeId="1" CreationDate="2016-04-14T12:22:58.703" Score="13" ViewCount="2769" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_720&quot;&gt;Boeing 720&lt;/a&gt; was a modification of the Boeing 707. Why was it given the unusual number of &quot;720&quot; instead of a &quot;707-xxx&quot; or &quot;7x7&quot; designation?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-01-24T04:27:14.303" LastActivityDate="2019-01-24T04:27:14.303" Title="Why did Boeing choose to give the Boeing 720 such a designation?" Tags="&lt;aviation-history&gt;&lt;aircraft-naming&gt;&lt;boeing-707&gt;&lt;boeing-720&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26917" PostTypeId="5" CreationDate="2016-04-14T12:25:20.593" Score="0" Body="&lt;p&gt;Aircraft companies give their own numbers and names to their own aircraft and aircraft get nicknames from what they are or what they do. This tag is used for questions asking why such names or numerical designations were given to a certain aircraft.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-14T13:15:49.800" LastActivityDate="2016-04-14T13:15:49.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26918" PostTypeId="4" CreationDate="2016-04-14T12:25:20.593" Score="0" Body="For questions about the name and/or number designation of aircraft." OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-09-29T01:06:07.983" LastActivityDate="2019-09-29T01:06:07.983" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26919" PostTypeId="2" ParentId="26910" CreationDate="2016-04-14T12:26:02.467" Score="42" Body="&lt;p&gt;Not yet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To look at a medium-range aircraft, let's base the engine on the &lt;a href=&quot;https://en.wikipedia.org/wiki/CFM_International_CFM56&quot; rel=&quot;noreferrer&quot;&gt;CFM56&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/IAE_V2500&quot; rel=&quot;noreferrer&quot;&gt;IAE V2500&lt;/a&gt;. Those engines produce between 100 and 150 kN static thrust. In cruise, their thrust is &lt;a href=&quot;https://engineering.purdue.edu/~propulsi/propulsion/jets/tfans/cfm56.html&quot; rel=&quot;noreferrer&quot;&gt;considerably lower&lt;/a&gt; due to the low density in cruise altitude and due to them moving at Mach 0.8. Let's use a value of 25 kN - this is enough so that two of them will comfortably push an &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A320_family&quot; rel=&quot;noreferrer&quot;&gt;A320&lt;/a&gt; class airframe through the thin air at altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The power to produce such an amount of thrust is force times speed. The speed when flying with Mach 0.8 in &lt;a href=&quot;http://www.wolframalpha.com/input/?i=speed%20of%20sound%20at%2035000%20ft%20altitude&quot; rel=&quot;noreferrer&quot;&gt;35.000 ft&lt;/a&gt; is 240 m/s, so the power produced by one engine is 6.0 MW. Now &lt;a href=&quot;https://en.wikipedia.org/wiki/Power-to-weight_ratio#Electric_motors.2FElectromotive_generators&quot; rel=&quot;noreferrer&quot;&gt;let's look up how big and heavy&lt;/a&gt; an electric motor has to be to produce 6 MW continuously. As you can see from the linked Wikipedia page, the results are all over the place. Big, industrial motors come in at less than 1 kW/kg, so our motor would weigh more than 6 tons. The smaller motors for electric airplanes are pushing 10 kW/kg, the power-to-weight ratio of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_GE90&quot; rel=&quot;noreferrer&quot;&gt;GE90 turbofan&lt;/a&gt;, but will lose some of that when scaled up to size. Remember, even at 98% efficiency the motor will generate 120 kW of heat - this needs to be removed, and operating in thin air doesn't make this easy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With current technology the motor could achieve maybe 2 to 3 kW/kg - this means the motor driving our hypothetical engine comes in at 2 to 3 tons. Add to this the fan and the fairing of the jet engine (we will not need the high-pressure part and all the turbines), but double the fan weight because we need to compensate for the missing high-energy core flow. This will maybe weigh 50% of the CFM56 / V2500, so we need to add another 1.2 tons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The electric motor will be twice as heavy as the parts it replaces. There is still some work to do before it can gain an advantage over current jet engines, but it has some potential because it does not dump half of the energy supplied to it overboard in a hot, fast-moving, noisy gas stream.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;EDIT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since so many people get excited about me omitting the energy density aspect of electric propulsion, even though the question did expressly desire to leave this out, here are &lt;strong&gt;two&lt;/strong&gt; things to consider. Energy density is only half of the problem of electric storage.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Energy_density#Energy_densities_of_common_energy_storage_materials&quot; rel=&quot;noreferrer&quot;&gt;energy density&lt;/a&gt; of jet fuel is around 43 MJ/kg, while Lithium polymer batteries achieve not even one MJ/kg. But this comparison is linear thinking - realistically, the current will be produced either by a high-efficiency turbine-generator combination, or by fuel cells, burning hydrogen at twice the efficiency of a conventional jet engine. Since hydrogen packs 142 MJ per kilogram, at twice the efficiency the electric airliner would need only 162 kg of hydrogen for every ton of kerosene in a conventional jet. Yes, I know, even then its volume will still be a problem.&lt;/li&gt;&#xA;&lt;li&gt;If any form of batteries is used, the fact that empty batteries weigh as much as full ones is the final nail in the coffin of battery-powered flight. While your average long-range jet &lt;a href=&quot;https://en.wikipedia.org/wiki/Fuel_fraction&quot; rel=&quot;noreferrer&quot;&gt;lands at 60% of its take-off weight&lt;/a&gt;, the battery-powered jet would need to schlepp those heavy batteries all the way to the final destination. To be competitive, those hypothetical batteries would need to have &lt;strong&gt;twice&lt;/strong&gt; the energy density of kerosene.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-08-29T08:35:12.957" LastActivityDate="2016-08-29T08:35:12.957" CommentCount="39" ContentLicense="CC BY-SA 3.0" />
  <row Id="26920" PostTypeId="5" CreationDate="2016-04-14T12:30:22.457" Score="0" Body="&lt;p&gt;The &lt;em&gt;Boeing 707&lt;/em&gt; was a narrowbody quadjet airliner formerly produced by &lt;a href=&quot;/questions/tagged/boeing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing&lt;/a&gt;; it was Boeing's first commercial &lt;a href=&quot;/questions/tagged/jet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;jet&amp;#39;&quot; rel=&quot;tag&quot;&gt;jet&lt;/a&gt;.  Though not the first jetliner, it became the first one to become commercially successful, and is credited with ushering in the jet age.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 707 (alongside its sister, the KC-135 &lt;a href=&quot;/questions/tagged/tanker&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tanker&amp;#39;&quot; rel=&quot;tag&quot;&gt;tanker&lt;/a&gt; aircraft) was developed from the one-off 367-80 (or &quot;Dash 80&quot;), a proof-of-concept for a Boeing jet-powered transport, which made its maiden flight on 15 July 1954.  While the KC-135 was essentially a straight tanker conversion of the 367-80, the 707 was redesigned early in development to use a significantly-wider fuselage in response to customer demand, allowing it to use six-abreast seating (three columns of seats on each side of a single central aisle); the 707 also had longer wings than the 367-80.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First flying on 20 December 1957, and entering revenue service on 26 October 1958, the 707 was the fifth jetliner in the air (following the &lt;a href=&quot;/questions/tagged/de-havilland-comet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;de-havilland-comet&amp;#39;&quot; rel=&quot;tag&quot;&gt;de-havilland-comet&lt;/a&gt;, Avro Canada Jetliner, &lt;a href=&quot;/questions/tagged/sud-caravelle&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;sud-caravelle&amp;#39;&quot; rel=&quot;tag&quot;&gt;sud-caravelle&lt;/a&gt;, and Tupolev &lt;a href=&quot;/questions/tagged/tu-104&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;tu-104&amp;#39;&quot; rel=&quot;tag&quot;&gt;tu-104&lt;/a&gt;), and the third in revenue service (after the Comet and Tu-104).  865 707s were built until production ended in 1979, plus 154 of the smaller, shorter-range &lt;a href=&quot;/questions/tagged/boeing-720&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-720&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-720&lt;/a&gt;, a 707 derivative; military versions of the 707 remained in production until 1991.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In its early years, the 707 mainly competed with the Douglas &lt;a href=&quot;/questions/tagged/dc-8&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;dc-8&amp;#39;&quot; rel=&quot;tag&quot;&gt;dc-8&lt;/a&gt;, which entered service eleven months after the 707, along with (to a much lesser extent) the later models of the Comet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seven major civilian versions of the 707 were produced:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The 707-120 was the first 707 version (produced from 1957 through 1960, and entering service in October 1958), which carried up to 189 passengers.  Powered by Pratt &amp;amp; Whitney JT3C &lt;a href=&quot;/questions/tagged/turbojet&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbojet&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbojet&lt;/a&gt; engines, it required a water-injection system in order to take off safely at maximum weight, and had a relatively short range (generally having to stop partway for fuel on &lt;a href=&quot;/questions/tagged/transatlantic&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;transatlantic&amp;#39;&quot; rel=&quot;tag&quot;&gt;transatlantic&lt;/a&gt; and transpacific routes).  63 were built (most of which were later converted to 707-120Bs), including seven 707-138s (a shorter-fuselage, longer-range 707-120 variant built especially for Qantas).&lt;/li&gt;&#xA;&lt;li&gt;The 707-320 was derived from the 707-120 by stretching the &lt;a href=&quot;/questions/tagged/fuselage&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;fuselage&amp;#39;&quot; rel=&quot;tag&quot;&gt;fuselage&lt;/a&gt;, the &lt;a href=&quot;/questions/tagged/wing&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;wing&amp;#39;&quot; rel=&quot;tag&quot;&gt;wing&lt;/a&gt;s, and the vertical and &lt;a href=&quot;/questions/tagged/horizontal-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;horizontal-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;horizontal-stabilizer&lt;/a&gt;s, and replacing the engines with more powerful JT4A turbojets; the larger wings increased its fuel capacity compared to the 707-120, allowing it to fly transoceanic routes without making a fuel stop en route.  Despite the longer fuselage, its maximum passenger capacity remained at 189 (as would that of all 707s until the 707-320C), the same as that of the 707-120.  69 707-320s were built from 1957 through 1963; the type entered revenue service in August 1959.&lt;/li&gt;&#xA;&lt;li&gt;The 707-220 featured the more powerful engines of the 707-320 (which it postdated, despite its lower version number), but without the latter version's various stretches.  It was designed for so-called &quot;hot and high&quot; operations (operations from high-altitude airports under conditions of high ambient temperature, both of which decrease air density, and, thus, aircraft performance; an example would be Mexico City in the summer), but was quickly rendered obsolete by the advent of the 707-120B (see below), and only five were built (one of which was destroyed in a training accident before it could be delivered), all for Braniff, with the first entering service in December 1959.&lt;/li&gt;&#xA;&lt;li&gt;The 707-420 was the first &lt;a href=&quot;/questions/tagged/turbofan&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;turbofan&amp;#39;&quot; rel=&quot;tag&quot;&gt;turbofan&lt;/a&gt;-powered 707, using the Rolls-Royce Conway engine; it was otherwise identical to the 707-320, with the exception of a larger &lt;a href=&quot;/questions/tagged/vertical-stabilizer&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;vertical-stabilizer&amp;#39;&quot; rel=&quot;tag&quot;&gt;vertical-stabilizer&lt;/a&gt;, modified &lt;a href=&quot;/questions/tagged/rudder&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;rudder&amp;#39;&quot; rel=&quot;tag&quot;&gt;rudder&lt;/a&gt; controls, and a small ventral fin under the tail (all added to meet British certification requirements), the former two of which would be adopted as standard on all 707s.  37 707-420s were built from 1960 until 1963, all for foreign airlines, with the type entering service in March 1960.&lt;/li&gt;&#xA;&lt;li&gt;The 707-120B, which carried its first passengers in March 1961, was similar to the 707-120, but used Pratt &amp;amp; Whitney JT3D turbofans, which were quieter, more powerful, and more fuel-efficient than the 707-120's JT3Cs, had a larger tail, and used the more aerodynamically-efficient wing pioneered by the 720 instead of the original 707-120 wing.  The water-injection system was also removed, as the more powerful engines eliminated the need for it.  78 707-120Bs were built new from 1960 through 1969, including six short-bodied, long-ranged 707-138Bs for Qantas (which were to the 707-120B what the original 707-138 was to the 707-120), but the changes could also be applied to already-built 707-120s, and 39 of the latter (including all seven 707-138s) were converted to 707-120B standard.&lt;/li&gt;&#xA;&lt;li&gt;The 707-320B was based off of the 707-320, with the &quot;B&quot; indicating - as with the 707-120B - that this was now a turbofan aircraft, using the same JT3Ds as the 707-120B.  Unlike with the 707-120B, the 707-320B's other aerodynamic improvements (mainly &lt;a href=&quot;/questions/tagged/drag&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;drag&amp;#39;&quot; rel=&quot;tag&quot;&gt;drag&lt;/a&gt;-reducing modifications to the wings) could not be retrofitted to an already-built 707-320, and all 175 707-320Bs were new builds.&lt;/li&gt;&#xA;&lt;li&gt;The 707-320C was the final, and most-produced, civilian 707, with 335 being built up until 1979.  It was designed to be easily converted from a passenger to a &lt;a href=&quot;/questions/tagged/cargo&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;cargo&amp;#39;&quot; rel=&quot;tag&quot;&gt;cargo&lt;/a&gt; aircraft and vice versa (hence the &quot;C&quot;, for &quot;convertible&quot;); however, the vast majority were used (at least at first) solely as passenger aircraft.  The 707-320C's maximum passenger capacity was greater than that of all previous 707 variants (219 rather than 189), due to it bearing a greater number of emergency exits.&lt;/li&gt;&#xA;&lt;li&gt;In the late 1970s, Boeing explored the possibility of building a new 707 variant: the 707-700, which would have been powered by the much more efficient General Electric/SNECMA CFM56 high-bypass turbofan.  A single aircraft was built to 707-700 standard, but, after testing, it was converted to a 707-320C and sold; however, the experience gained with the CFM56 from the 707-700 program was put to valuable use when the U.S. Air Force began reengining its KC-135s (which are, you will recall, a close sister to the 707) with the CFM56, starting in 1980, and the CFM56 was also chosen to power all post-1980 military 707s.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Boeing removed the 707 from its product offerings in 1980 (except for the military variants).  By then, the market it had originally filled had mostly passed to large widebody (twin-aisle) aircraft, such as the &lt;a href=&quot;/questions/tagged/boeing-747&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-747&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-747&lt;/a&gt;, and the 707 was left without a direct replacement (although the &lt;a href=&quot;/questions/tagged/boeing-757&quot; class=&quot;post-tag&quot; title=&quot;show questions tagged &amp;#39;boeing-757&amp;#39;&quot; rel=&quot;tag&quot;&gt;boeing-757&lt;/a&gt;, introduced into service in 1983, comes close).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To learn more about the 707, &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_707&quot; rel=&quot;nofollow noreferrer&quot;&gt;see Wikipedia&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-09-25T07:53:07.820" LastActivityDate="2019-09-25T07:53:07.820" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26921" PostTypeId="4" CreationDate="2016-04-14T12:30:22.457" Score="0" Body="For questions about the Boeing 707 family of airliners, a series of narrowbody quadjets produced from 1957 through 1979." OwnerUserId="12220" LastEditorUserId="22726" LastEditDate="2019-01-17T15:05:48.573" LastActivityDate="2019-01-17T15:05:48.573" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="26922" PostTypeId="2" ParentId="26916" CreationDate="2016-04-14T12:30:28.227" Score="23" Body="&lt;p&gt;Because the launch customer, United Airlines wanted it. From &lt;a href=&quot;http://www.boeing.com/news/frontiers/archive/2004/february/i_history.html&quot;&gt;Boeing frontiers&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The 720 was a ... first marketed to the airlines as the model 707-020. United Airlines was very interested in the 707-020 but had previously decided to go with Douglas and the DC-8. To help United avoid any negative public relations for going back to the 707, Boeing changed the name of the 707-020 to the 720. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to &lt;a href=&quot;http://aviationweek.com/blog/farewell-boeings-720&quot;&gt;aviationweek&lt;/a&gt;, the name change was at the behest of William ‘Pat’ Patterson, the president of launch customer United Airlines.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-04-14T15:14:53.347" LastActivityDate="2016-04-14T15:14:53.347" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="26926" PostTypeId="2" ParentId="9869" CreationDate="2016-04-14T14:30:45.310" Score="3" Body="&lt;p&gt;If you want to maximize your budget including saving valuable time, make sure you like him or her and their teaching style fits your learning style but more importantly if the instructor ever had a student fail a checkride. How many students has he or she recommended who have passed THE FIRST TIME.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each checkride can cost $500 or more. That usually applies to retakes. A students performance in the checkride is a direct reflection of the instructor. Things happen, retakes or partial retakes happen. But quite frankly, CFIs who work independently often leave gaps in the students' learning. The checkride examiner shouldn't be the one to find the deficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It always pays to have a good instructor, a good syllabus, and a structured environment in which to learn. One in which there are several experienced instructors who contribute to the student's success. &lt;/p&gt;&#xA;" OwnerUserId="14474" LastEditorUserId="3386" LastEditDate="2016-04-14T16:46:32.550" LastActivityDate="2016-04-14T16:46:32.550" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26927" PostTypeId="2" ParentId="26910" CreationDate="2016-04-14T15:05:41.513" Score="12" Body="&lt;p&gt;There is one important disadvantage that batteries will always have compared with fuel combustion for aviation propulsion: the weight remains constant. Airliners (especially those used for long-haul flights) burn off a large percentage of their take-off mass over the course of the flight. Batteries, however, retain their initial mass constantly. This is a problem for a number of reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The most obvious reason this is a problem is that more energy is required for the flight. Even if you get a battery that has equal energy density to jet fuel and is also stable (which we are currently quite far from,) the airplane will need to carry the entire mass of the batteries for the entire duration of the flight. Thus, as the flight goes on, far more energy will be used per mile on a battery-powered flight than on a fuel-powered one, even if the batteries have the same energy density as the fuel. This also means that even more battery mass will be needed for the same range, since that extra energy requirement has to come from the batteries.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The other big problem is maximum landing weight. Many airliners are not designed to be able to land at their maximum takeoff weight simply because it isn't needed. This is one of the reasons why fuel sometimes needs to be dumped or burnt off before an aircraft that encounters a problem after takeoff can land again. However, with batteries, you'll still be at take-off weight when you're landing, which means you'll need stronger landing gear and tires, which means yet more weight and design/manufacturing cost. It also means you'll be landing faster (because of the extra weight,) so you'll need more runway length to land as well as needing brakes that can absorb more energy. The kinetic energy of the airplane is equal to half its mass times its speed squared, so the energy that must be absorbed by the brakes during landing increases dramatically as landing weight and speed increases.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A somewhat less important, but still significant problem is more punishment to runway surfaces. With planes now landing near their MTOW, runways surfaces will be damaged more quickly and will need to be resurfaced more often and/or designed for larger loads than they are now. This would also probably mean that the aircraft wouldn't be able to access as many runways as an otherwise-equivalent fuel-powered aircraft would be able to use until those runways were strengthened.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Of course, you could start jettisoning battery cells as they're depleted, but this also (obviously) has a lot of problems:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;In order to deplete some batter cells sooner than others, you won't be able to draw on all cells in parallel, which will mean higher power draw levels per cell (and, thus, more heat produced per unit time per active cell, etc.)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;You'll need to design the airplane to be able to jettison the cells safely. This is doable, but will require lots of extra cost in design effort and extra weight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Environmentalists won't be too happy when you start dropping huge batteries all over the place. Neither will property owners. Existing battery chemistries are already quite corrosive and a battery chemistry with the energy density of Jet-A is probably going to be even more corrosive, unstable, and otherwise bad for whatever it's dropped on.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="755" LastEditorUserId="755" LastEditDate="2016-04-14T15:43:27.693" LastActivityDate="2016-04-14T15:43:27.693" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26928" PostTypeId="1" AcceptedAnswerId="26933" CreationDate="2016-04-14T16:25:33.140" Score="4" ViewCount="4144" Body="&lt;p&gt;I work with small commercial aircraft. Up until now I have understood Part 91 to mean that the flight has been filed as private and Part 135 to mean that the flight has been filed as commercial, to put it simply.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recently, after a problem I can't go into, my colleague suggested that the problem could have been caused if the carrier was not &quot;Part 129 approved&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the difference between Part 129 and Part 135?&#xA;Are there any cases in which you would need one and not the other, or both, or neither?&#xA;Are there any other &quot;Parts&quot; that can affect a foreign carrier flying to/from/within the US?&lt;/p&gt;&#xA;" OwnerUserId="9867" LastActivityDate="2016-04-14T18:20:33.837" Title="What is the difference between Part 135 and Part 129?" Tags="&lt;faa-regulations&gt;&lt;flight-planning&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26929" PostTypeId="2" ParentId="26906" CreationDate="2016-04-14T16:40:41.913" Score="21" Body="&lt;p&gt;It's not quite as big as the Antonov An-124, but honorable mention would have to go to the &lt;a href=&quot;http://www.popularmechanics.com/flight/g634/how-the-lc-130-flies-to-greenland-and-antarctica/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed LC-130&lt;/a&gt;.  It's designed to resupply scientific and military operations in polar regions, and so it has a dual wheel-and-ski landing gear setup that allows it to take off from and land on snow and ice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/unWLY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/unWLY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:LC130-Takeoff-Greenland.swn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;(Image source:  Wikimedia Commons)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13297" LastActivityDate="2016-04-14T16:40:41.913" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26930" PostTypeId="2" ParentId="26906" CreationDate="2016-04-14T17:34:36.237" Score="15" Body="&lt;p&gt;Going off on another direction if ice counts as &amp;quot;unpaved&amp;quot;, &lt;a href=&quot;http://mashable.com/2015/11/27/antarctica-flights/#kj4shOBAhmqg&quot; rel=&quot;noreferrer&quot;&gt;a Boeing 757&lt;/a&gt; was landed in Antarctica in November 2015, the first commercial airliner to do that.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2xJ3x.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2xJ3x.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Source is from the link above.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-14T17:34:36.237" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26931" PostTypeId="2" ParentId="26900" CreationDate="2016-04-14T17:43:23.493" Score="1" Body="&lt;p&gt;Some simple helicopter models like &lt;a href=&quot;https://en.wikipedia.org/wiki/Bamboo-copter&quot; rel=&quot;nofollow&quot;&gt;bamboo copter&lt;/a&gt; use rotary inertia as the power source. Either rotor or, in some cases, the whole simple model is spun up on the ground, providing enough rotating energy for the short flight with the help of the blades, same as for the real helicopter. However I am not aware of the full scale machines relying on such a power source.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-04-14T17:49:23.850" LastActivityDate="2016-04-14T17:49:23.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26932" PostTypeId="1" AcceptedAnswerId="26936" CreationDate="2016-04-14T18:01:00.330" Score="5" ViewCount="1120" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YRKuX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YRKuX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ygT4A.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ygT4A.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Wolfgang Langewiesche - Stick and Rudder; An Explanation of the Art of Flying&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Why is it called a mushing glide?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In this glide, does the aircraft point its nose less (or more?) steeply? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;How does it steepen the descent?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;I find the explanation confusing. At one point it seems that a mushing glide is caused by a high AOA and at another point it seems that a low AOA (pointing slightly above horizon) causes it.&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="13197" LastEditDate="2016-04-16T21:27:15.423" LastActivityDate="2016-04-16T21:27:15.423" Title="What is a mushing glide?" Tags="&lt;glider&gt;&lt;descent&gt;&lt;glide-ratio&gt;&lt;nose&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26933" PostTypeId="2" ParentId="26928" CreationDate="2016-04-14T18:20:33.837" Score="5" Body="&lt;p&gt;I'm not at all sure what you're asking, but maybe I can at least point you towards more information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, the parts you mentioned define operating rules for different flight types (I'm simplifying a bit here):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 91&lt;/a&gt;: rules for all flights in the US&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr121_main_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 121&lt;/a&gt;: rules for flights by a US airline&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:3.0.1.1.9&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 129&lt;/a&gt;: rules for flights by a foreign airline in the US&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr135_main_02.tpl&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part 135&lt;/a&gt;: rules for 'on demand' (usually charter) flights by a US operator&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Any given flight will operate under one or more of those sets or rules, e.g. a US airline flight from New York to Los Angeles would follow the rules in parts 91 and 121; a foreign flight from London to New York would follow parts 91 and 129 (while in US airspace). Individual operators and airlines also have &lt;a href=&quot;https://aviation.stackexchange.com/q/1641/62&quot;&gt;OpSpecs&lt;/a&gt; that are approved by the FAA and that can add more rules for specific situations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And I'm not entirely sure, but it looks like &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&amp;amp;node=14:3.0.1.1.9#se14.3.129_119&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 129.119(c)&lt;/a&gt; effectively applies part 121 to foreign airlines too, by requiring them to comply with the same rules as US airlines:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(c) Each foreign air carrier shall conform to the practices,&#xA;  procedures, and other requirements prescribed by the Administrator for&#xA;  U.S. air carriers for the areas to be operated in.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Without knowing what your mysterious problem was (and I understand you can't share it), I don't think it's possible to say much more than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By the way, &quot;filing&quot; is something different. Filing a flight plan is required &lt;a href=&quot;https://aviation.stackexchange.com/q/1612/62&quot;&gt;for various reasons&lt;/a&gt; but they apply to all aircraft, even private flights. If I want to fly a C172 under IFR then I have to file essentially the same flight plan information that an A380 pilot will file.)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-04-14T18:20:33.837" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26934" PostTypeId="1" CreationDate="2016-04-14T18:21:30.207" Score="1" ViewCount="159" Body="&lt;p&gt;CPL holder can be PIC on any plane if it's not a commercial air transport. So if the flight is positioning, acceptance, testing, delivery or any other without cargo and passengers any CPL holder provided he/she has TR and special training for the left seat can act as PIC? Do airlines allow this maybe as bonus for young first officers? &#xA;Another option is big business jets like 737 747 BBJ, A319...&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-10-01T21:25:15.590" Title="Are there any low time lucky CPL holders who operate as PIC on medium or heavy jets?" Tags="&lt;regulations&gt;&lt;cpl&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26935" PostTypeId="2" ParentId="26932" CreationDate="2016-04-14T18:46:10.383" Score="6" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Why is it called a mushing glide?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aircraft is not cleanly cutting through the air. It is &quot;mushing&quot; through the air at a high angle of attack creating lots of drag and a slow forward airspeed.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In this glide, does the aircraft points its nose less (or more?) steeply?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aircraft has its nose pointed up (less steeply) than a normal glide.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does it steepen the descent?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The low forward airspeed and high drag creates a high rate of sink relative to the forward motion. Low forward speed and relatively high sink rate means the descent will be very steep. A fully stalled condition would be an extreme example of a &quot;mushing&quot; glide.  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;low AOA (pointing slightly above horizon) causes it.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;pointing the nose slightly above the horizon is still a High Angle of Attack, not low AOA. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="1467" LastEditDate="2016-04-15T11:12:13.503" LastActivityDate="2016-04-15T11:12:13.503" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26936" PostTypeId="2" ParentId="26932" CreationDate="2016-04-14T18:48:16.453" Score="5" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;It is called &quot;mushing&quot; probably because the controls will be a little mushy (soft). At high angles of attack you begin to lose control authority and the controls can feel soft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The nose will be pointed slightly above horizon.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When you pull back on the stick your forward velocity will decrease, but your rate of vertical descent will stay the same or decrease by only a small amount, so your angle of descent will become more steep.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Let's put some numbers on this and make a &quot;real&quot; example. Let's imagine you are in a sailplane which is in a configuration that stalls around 35 mph. You are currently travelling at 45 mph in a level flight attitude, descending at 150 feet per minute. You will be on 2-degree glide slope (confirm this for yourself). Ok, now pull back on the stick until you are going about 37 mph. At this point the controls will start to get soft. Your vertical speed may decrease to about 140 feet per minute. Your glide slope will increase to 2.5-degrees. Thus by this maneuver your glide slope increases (becomes more steep).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just as a further exercise, let's compute how much we can change our touchdown point by the above maneuver. Suppose we are at 200 feet AGL, then we will touchdown in about 5200 feet in the beginning attitude (confirm this for yourself). Okay, now we pull back the stick to 37 mph (&quot;mushing&quot; descent to use Langewiesche's terminology) and our vertical speed goes to -140 FPM. How much does this change our touchdown point? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you do the math, you will find our touchdown point changes from 5200 feet to 4650, a difference of over 600 feet. So, by using a &quot;mushing&quot; glide we have changed our touchdown point significantly. Let's just illustrate it with a real airfield:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FOoFL.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FOoFL.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, here we see our current position at the circle. If we continue on our current glide path we touch down in 5200. It's too close to the crossover on the runway. We would much rather land at the blue line. By using a mushing glide we could accomplish that. &lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-04-14T23:06:19.107" LastActivityDate="2016-04-14T23:06:19.107" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26937" PostTypeId="1" CreationDate="2016-04-14T19:02:46.480" Score="5" ViewCount="597" Body="&lt;p&gt;Are there any visual differences between a Trent 892 and a Trent 900 engine?&#xA;Particularly referring to the ones mounted on the 777-200.&lt;/p&gt;&#xA;" OwnerDisplayName="user14481" LastEditorUserId="4095" LastEditDate="2016-04-14T22:54:45.100" LastActivityDate="2018-03-03T15:25:15.803" Title="What are the visual differences between Trent 892 and 900 engines?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;multi-engine&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26938" PostTypeId="2" ParentId="26916" CreationDate="2016-04-14T19:05:42.773" Score="3" Body="&lt;p&gt;The 720 first flew before the 727 project began. At that time, there was no &quot;7x7 series&quot;&amp;nbsp;&amp;ndash; just the 707.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(The 717 passenger plane didn't come along until the 1990s, though the internal Boeing model number of what are usually called the C-135 Stratolifter and KC-135 Stratotanker was also 717, and that did exist at the time the 720 was produced.)&lt;/p&gt;&#xA;" OwnerUserId="946" LastEditorUserId="946" LastEditDate="2016-04-14T20:43:37.343" LastActivityDate="2016-04-14T20:43:37.343" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26939" PostTypeId="1" CreationDate="2016-04-14T19:11:12.337" Score="9" ViewCount="619" Body="&lt;p&gt;Keeping in mind that a plane can fly with different engine models (&lt;a href=&quot;https://youtu.be/2lcGKbfQy3w?t=57s&quot; rel=&quot;nofollow&quot;&gt;e.g. for test purposes&lt;/a&gt;), has an error ever happened during normal operations that led to the wrong engine being mounted? Is some kind of calibration or check necessary before flight to ensure that the engines are the correct ones?&lt;/p&gt;&#xA;" OwnerDisplayName="user14481" LastEditorUserId="62" LastEditDate="2016-07-19T12:21:45.863" LastActivityDate="2017-05-11T09:59:33.743" Title="Has the wrong engine ever been mounted after maintenance?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;flight-testing&gt;&lt;multi-engine&gt;" AnswerCount="1" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26940" PostTypeId="1" CreationDate="2016-04-14T19:49:50.890" Score="6" ViewCount="598" Body="&lt;p&gt;MH370 Factual Information reported &quot;Right engine consumes average 1.5T more fuel per/hour compared to left engine&quot; on p.28 (page 47 on page count)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://mh370.mot.gov.my/download/FactualInformation.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://mh370.mot.gov.my/download/FactualInformation.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking at spotters photos on the web I spotted the following difference:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Some kind of visible replacement (partial or total) to the left engine was made after Oct 28 '13 and before Jan 22 '14.&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Before&lt;/strong&gt; - Two shades, longer curving, bigger bulge on top engine border before exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;After&lt;/strong&gt; - One shade, steeper curving, smaller bulge on top engine border before exhaust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Google Drive document with links to 9M-MRO photos (I can't post more than 2 links since not enough reputation still)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://docs.google.com/document/d/1tkY6H8zQmOyJj0M2_gd_j81iDr2MeumBoIlrYNtbcus/edit?usp=sharing&quot; rel=&quot;noreferrer&quot;&gt;https://docs.google.com/document/d/1tkY6H8zQmOyJj0M2_gd_j81iDr2MeumBoIlrYNtbcus/edit?usp=sharing&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerDisplayName="user14481" LastEditorUserId="1467" LastEditDate="2016-04-14T20:41:17.160" LastActivityDate="2016-04-15T00:50:35.143" Title="What was the reason why 9M-MRO burned more fuel on one engine?" Tags="&lt;jet-engine&gt;&lt;engine&gt;&lt;boeing-777&gt;&lt;mh370-incident&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ClosedDate="2016-04-20T05:00:38.993" ContentLicense="CC BY-SA 3.0" />
  <row Id="26941" PostTypeId="2" ParentId="26940" CreationDate="2016-04-14T21:14:04.147" Score="10" Body="&lt;p&gt;Those engines all look the same to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1.5T per/hour difference does seem excessive, but probably not unheard of.  It could be just because one engine is newer than the other and has less wear on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look at APPENDIX 1.6B of that same report it shows that the right engine consumed about 1.5% more fuel during Takeoff and Climb, not 1.5T more, so it may just be a typo. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(APPENDIX 1.6B WF is fuel flow in lbs/hr)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/lphf9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/lphf9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/NnxY1.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NnxY1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some crops of the photos you linked to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ceWvh.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ceWvh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Jan. 15, 2012 &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/japsj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/japsj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Feb. 16, 2013&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VL4Ot.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VL4Ot.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Oct. 28,2013&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RZJzq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RZJzq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Jan. 22, 2014&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/w5iWj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/w5iWj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Feb. 8, 2014&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fYaey.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fYaey.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Feb. 10, 2014&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ASMnk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ASMnk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="8730" LastEditDate="2016-04-15T00:50:35.143" LastActivityDate="2016-04-15T00:50:35.143" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26942" PostTypeId="2" ParentId="26771" CreationDate="2016-04-14T22:20:52.830" Score="1" Body="&lt;p&gt;No, you will most likely not get a TIS-B service dedicated to your aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TIS-B transmitting system creates a 'traffic puck' around aircraft that: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) have a version 2 ADS-B transmitter,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;b) transmit the proper quality indicators which indicates that the system is certified and is properly functioning, and&lt;/p&gt;&#xA;&#xA;&lt;p&gt;c) indicate in their ADS-B transmissions that the aircraft is equipped with ADS-B IN. (see &lt;a href=&quot;https://www.faa.gov/nextgen/programs/adsb/faq/#34&quot; rel=&quot;nofollow&quot;&gt;FAA ADS-B FAQ #34&lt;/a&gt;, link provided by @Rigged4Flight ) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically TIS-B will provide information on the same frequency as the ADS-B transmitter, but the ADS-B protocol allows for indicating a different technology is used for ADS-B IN. I am not sure whether the FAA system uses this information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: currently version 1 ADS-B aircraft with sufficient data quality are also still eligible for TIS-B services, however this will change in the next couple of years.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-05-03T09:20:38.833" LastActivityDate="2016-05-03T09:20:38.833" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26943" PostTypeId="2" ParentId="26906" CreationDate="2016-04-14T22:29:42.800" Score="19" Body="&lt;p&gt;These oldies seem worth mentioning...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you loosen your definition of &quot;airplane&quot; to &quot;&lt;em&gt;the longest class of flying machine and the largest airship by envelope volume&lt;/em&gt;&quot; you could think of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Hindenburg-class_airship&quot; rel=&quot;noreferrer&quot;&gt;Hindenburg-class airship&lt;/a&gt; that &lt;em&gt;was&lt;/em&gt; in regular commercial service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They landed in  fields &lt;a href=&quot;https://i.stack.imgur.com/qQURv.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qQURv.jpg&quot; alt=&quot;field&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're more comparable in size to buildings or very large boats, rather than other airplanes &#xA; &lt;a href=&quot;https://i.stack.imgur.com/kDJrM.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kDJrM.png&quot; alt=&quot;size&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hindenburg in green compared to&lt;br&gt;&#xA;  Blue: The Pentagon building,&lt;br&gt;&#xA;  Pink: Queen Mary 2, ocean liner&lt;br&gt;&#xA;  Yellow: USS Enterprise, supercarrier&lt;br&gt;&#xA;  Dark blue: Yamato, WWII Japanese warship&lt;br&gt;&#xA;  Grey: Empire State Building&lt;br&gt;&#xA;  Red: Mont, a supertanker&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Compared to other airplanes (Hindenburg in orange): &lt;a href=&quot;https://i.stack.imgur.com/yj5JX.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yj5JX.png&quot; alt=&quot;planes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Or the &lt;a href=&quot;http://www.evergreenmuseum.org/the-spruce-goose&quot; rel=&quot;noreferrer&quot;&gt;Spruce Goose (* Not acutal Spruce)&lt;/a&gt;. &lt;sub&gt;(Just noticed it mentioned in another answer, &lt;em&gt;after&lt;/em&gt; posting this)&lt;/sub&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Originally designated HK-1 for the first aircraft built by Hughes-Kaiser, the giant was re-designated H-4 when Henry Kaiser withdrew from the project in 1944. Nevertheless, the press insisted on calling it the “Spruce Goose” despite the fact that the plane is made almost entirely of birch.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Apparently it is &lt;em&gt;&quot;the largest flying boat ever built and has the largest wingspan of any aircraft in history&quot;&lt;/em&gt; at 320 ft 11 in (97.54 m). Not strictly a &quot;regularly used&quot; airplane, but&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Hughes retained a full crew to maintain the mammoth plane in a climate-controlled hangar up until his death in 1976.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HSs2e.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HSs2e.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="4506" LastActivityDate="2016-04-14T22:29:42.800" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26944" PostTypeId="1" AcceptedAnswerId="26980" CreationDate="2016-04-14T22:44:22.647" Score="10" ViewCount="317" Body="&lt;p&gt;Since the beginning of commercial jets, constructors thrived to make planes more fuel efficient. I assume most gains since then come from cleaner aerodynamic design, weight savings, and engine design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, these are not the only factors to take into account.&#xA;For example, we have also became better at predicting meteo, or transmitting live information about airstreams so that planes can spend more time in the most favorable zones.&#xA;Traffic control can also improve fuel efficiency by optimizing the landings of planes or reducing taxi/idle time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much of the gain in efficiency can be attributed to this factors ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to phrase it would be: How much more fuel efficient would it be to fly an old plane with modern avionics today? &lt;/p&gt;&#xA;" OwnerUserId="4105" LastEditorUserId="13197" LastEditDate="2016-04-16T21:11:21.893" LastActivityDate="2016-04-16T21:11:21.893" Title="How much efficiency gain can be attributed to aircraft handling?" Tags="&lt;commercial-aviation&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26945" PostTypeId="5" CreationDate="2016-04-14T22:59:02.273" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-04-14T22:59:02.273" LastActivityDate="2016-04-14T22:59:02.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26946" PostTypeId="4" CreationDate="2016-04-14T22:59:02.273" Score="0" Body="The structure of an aircraft, including the fuselage, wings, and landing gear, but excluding the propulsion system." OwnerUserId="4095" LastEditorUserId="12720" LastEditDate="2016-04-14T23:19:34.333" LastActivityDate="2016-04-14T23:19:34.333" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26947" PostTypeId="2" ParentId="26937" CreationDate="2016-04-14T23:12:57.237" Score="9" Body="&lt;p&gt;The main difference between the two installed engines would be the fan blades. The 892 uses hollow wide chord Ti blades, like shown below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/xp0pP.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xp0pP.jpg&quot; alt=&quot;Trent 892&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Cory W. Watts from Madison, Wisconsin, United States of America - Rolls Royce Trent 892 [777-200ER], CC BY-SA 2.0, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=43524027&quot; rel=&quot;noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=43524027&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Trent 900, on the other hand, uses a swept design to reduces the effect of shock waves. From &lt;a href=&quot;http://www.rolls-royce.com/products-and-services/civil-aerospace/products/civil-large-engines/trent-900.aspx#technology&quot; rel=&quot;noreferrer&quot;&gt;RR site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The engine’s 24 fan blades are to a new swept design that reduces the effect of shock waves, as the tip of the fan rotates supersonically, making it lighter, quieter and more efficient&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/30iKO.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/30iKO.jpg&quot; alt=&quot;Trent 900&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.imageresourcemedia.com/broadcast/streaming_site/pages/Trent%20900%20build.jpg&quot; rel=&quot;noreferrer&quot;&gt;imagesourcemedia.com&lt;/a&gt;; appears to be taken from RR site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the Trent 900 is exclusively for A380.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-14T23:12:57.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26949" PostTypeId="2" ParentId="26686" CreationDate="2016-04-15T05:39:30.730" Score="11" Body="&lt;p&gt;The best explanation I've seen for the logic behind the 35 foot crossing height requirement can be found in the FAA Instrument Procedures Handbook (IPH). It's available from the FAA website at this link: &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In Chapter 1, Departure Procedures, under Design Criteria on page 1-16: &amp;quot;The aircraft climb path assumption provides a minimum of 35 feet of additional obstacle clearance above the required obstacle clearance (ROC), from the DER outward, to absorb variations ranging from the distance of the static source to the landing gear, to differences in establishing the minimum 200 FPNM climb gradient, etc.&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;So, the 35 feet is in place to account for a multitude of variables. The phrase &amp;quot;differences in establishing the minimum 200 FPNM (Feet Per Nautical Mile) climb gradient&amp;quot; covers a whole host of potential errors such as variations in individual aircraft performance, early rotation, late rotation, under rotation, over rotation, poor airspeed control, etc. This error proofing is important since the 35 foot requirement is used when building all performance data for go and no-go decisions. That performance data is all based on set assumptions. Reasonable deviations from the assumptions are mitigated (somewhat) by the 35 foot margin.&lt;/p&gt;&#xA;&lt;p&gt;As with most safety margins, there isn't necessarily a precise reason for the size of the buffer. However, even increasing the crossing height a slight amount, say to 50 feet can have significant effect on performance calculations. At a minimum climb gradient of 200 FPNM, the difference between a screen height of 35 feet and 50 feet is just over 450 feet of required horizontal distance. In a tight performance situation such as high pressure elevation or short runways, a 50 foot crossing height could be too much for some large commercial aircraft.&lt;/p&gt;&#xA;&lt;p&gt;Of note, the regulation that created the 35 foot crossing height, SR422, came about in the late 50s during the beginning of jet-powered commercial aviation. The aircraft being designed and fielded back then, the Boeing 707 for example, would have had a hard time making a higher restriction. That likely had influence on the required crossing height.&lt;/p&gt;&#xA;" OwnerUserId="14495" LastEditorUserId="5517" LastEditDate="2020-07-08T01:16:44.180" LastActivityDate="2020-07-08T01:16:44.180" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="26950" PostTypeId="1" AcceptedAnswerId="26955" CreationDate="2016-04-15T09:56:39.093" Score="20" ViewCount="2350" Body="&lt;p&gt;Seeing the image of a Lockhead LC-130 doing a jet assisted takeoff in snow mentioned in this &lt;a href=&quot;https://aviation.stackexchange.com/a/26929/3027&quot;&gt;answer&lt;/a&gt;, I wonder: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the procedure for a rejected takeoff when using JATO?&#xA;Can the JATO rockets be turned off once ignited?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XZiM9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XZiM9.jpg&quot; alt=&quot;LC130 JATO Takeoff&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:LC130-Takeoff-Greenland.swn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;(Image source:  Wikimedia Commons)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3027" LastEditorUserId="22726" LastEditDate="2019-03-27T21:31:49.243" LastActivityDate="2021-02-28T17:48:51.183" Title="What is the procedure for a rejected Jet/Rocket Assisted Takeoff (J/RATO)?" Tags="&lt;takeoff&gt;&lt;rejected-takeoff&gt;&lt;rato&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26952" PostTypeId="1" AcceptedAnswerId="26953" CreationDate="2016-04-15T11:41:17.867" Score="7" ViewCount="1336" Body="&lt;p&gt;Due to financial impediments (other priorities in life) I had to postpone my PPL. While browsing the questions on the site here, I was having a look at this question: &lt;a href=&quot;https://aviation.stackexchange.com/questions/738/can-microsoft-flight-simulator-help-me-learn-to-fly-or-make-me-a-better-pilot/744#744&quot;&gt;&lt;em&gt;Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?&lt;/em&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In that question there is an &lt;a href=&quot;https://aviation.stackexchange.com/a/746/62&quot;&gt;answer&lt;/a&gt; by abelenky where he posts a &lt;a href=&quot;https://i.stack.imgur.com/91TBhm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;picture of his old simulator rig&lt;/a&gt;. I was wondering about the process to put a similar simulator rig together.&lt;/p&gt;&#xA;&lt;p&gt;What hardware and software would I need? I've heard about joysticks, but is it necessary to have &lt;a href=&quot;https://answers.yahoo.com/question/index?qid=20100613121247AA8Uaxx&quot; rel=&quot;nofollow noreferrer&quot;&gt;pedals to move the rudder&lt;/a&gt;? To make things as specific as possible, here's how I imagine using it:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The purpose of the simulator&lt;/p&gt;&#xA;&lt;p&gt;I would like to practice the use of the instruments while enjoying myself. Maybe flying some of my favourite second world war planes for instance, if possible.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What types of planes and flying is it for?&lt;/p&gt;&#xA;&lt;p&gt;I would see what is available. I have been flying only Cessnas so far. I would love to fly a &lt;a href=&quot;https://en.wikipedia.org/wiki/Focke-Wulf_Fw_190&quot; rel=&quot;nofollow noreferrer&quot;&gt;Focke-Wulf Fw 190&lt;/a&gt; if it's possible.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What types of training or practice?&lt;/p&gt;&#xA;&lt;p&gt;Navigation, landing, instruments, anything to help with the PPL.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;https://aviation.stackexchange.com/questions/2489/i-want-to-build-a-flight-simulator?rq=1&quot;&gt;This&lt;/a&gt; is a similar question; it has been closed because it was too broad, since it asked about all possible solutions. I'm only asking which are the essential components to make a basic simulator for PPL-level skills.)&lt;/p&gt;&#xA;" OwnerUserId="11358" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-15T20:18:10.283" Title="What hardware and software is needed to put together a basic flight simulator?" Tags="&lt;flight-training&gt;&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="26953" PostTypeId="2" ParentId="26952" CreationDate="2016-04-15T12:08:54.177" Score="8" Body="&lt;p&gt;&lt;em&gt;(first off, I need to post a new picture of my sim rig soon.  It's improved since then)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;1. Yoke vs. Stick&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Try to model it after a plane you're actually going to fly.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;If it's a yoke-controlled model (like a Cessna), then you should have a Yoke.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;If you're working towards a stick controlled plane (like a Piper Cub), then you should get a simple joystick (not a fighter-pilot-styled super fancy one).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I have this model: &lt;a href=&quot;https://i.stack.imgur.com/yex49.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yex49.jpg&quot; alt=&quot;Pro-Flight Yoke&quot;&gt;&lt;/a&gt;&#xA;But I want to upgrade to: &lt;a href=&quot;https://i.stack.imgur.com/GvVWE.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GvVWE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;2. Throttle&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;After that, I think a throttle is important.&#xA;Making the throttle precisely mirror your chosen airplane is not as important.&#xA;(pushing a lever is pretty similar to pushing a control rod).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The three-lever model comes with the Pro Flight Yoke.&#xA;Or you can get a a Push-rod version like this:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Xn9Cg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Xn9Cg.jpg&quot; alt=&quot;Throttle Prop Mix controls&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;(more updates when I have time)&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="1467" LastEditDate="2016-04-15T12:22:15.750" LastActivityDate="2016-04-15T12:22:15.750" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26954" PostTypeId="1" CreationDate="2016-04-15T12:42:09.233" Score="4" ViewCount="1383" Body="&lt;p&gt;What type Altimeter is an SA-91? It has three pointers 100, 1000, 10000.&#xA;Don't know if it is Kollsman. I can't find any info as far as repairing unit.&lt;a href=&quot;https://i.stack.imgur.com/xrPjn.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/xrPjn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14501" LastEditorUserId="1467" LastEditDate="2016-04-15T12:46:54.473" LastActivityDate="2016-04-16T23:54:06.907" Title="What type of altimeter is this?" Tags="&lt;military&gt;&lt;flight-instruments&gt;&lt;altimeter&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26955" PostTypeId="2" ParentId="26950" CreationDate="2016-04-15T13:54:44.523" Score="21" Body="&lt;p&gt;&lt;a href=&quot;https://wikipedia.org/wiki/JATO&quot; rel=&quot;nofollow noreferrer&quot;&gt;JATO&lt;/a&gt; (more correctly: RATO) typically uses simple &lt;a href=&quot;https://wikipedia.org/wiki/Solid-fuel_rocket&quot; rel=&quot;nofollow noreferrer&quot;&gt;solid-fuel rockets&lt;/a&gt; for their ease of maintenance, simple construction, long-term storability, robustness, and reliability. However, a simple solid-fuel rocket has to burn out once ignited, there is no way to shut it down. Techniques for extinguishing and even &lt;a href=&quot;http://google.com/patents/US8336287&quot; rel=&quot;nofollow noreferrer&quot;&gt;throttling&lt;/a&gt; solid-fuel rockets &lt;em&gt;do&lt;/em&gt; exist, but they were developed rather recently, have not yet been commercialized, and clash with the goal of simplicity.&lt;/p&gt;&#xA;&lt;p&gt;Currently, the &amp;quot;usual&amp;quot; way to shut down a solid-fuel rocket is to rapidly decrease the pressure in the combustion chamber, aka an explosive Flight Termination System, aka blowing up the rocket – not something you want to happen with a rocket strapped to your wings (IOW directly below the fuel tanks). Alternatively, you could get rid of that extra thrust by jettisoning the rockets. Having a dozen or so flaming projectiles uncontrollably flying around the airplane is also not a good idea.&lt;/p&gt;&#xA;&lt;p&gt;So, you either reject before igniting the rockets or you don't reject at all. V₁ is when you hit the button, which may be as low as 0 kt, depending on the specific application.&lt;/p&gt;&#xA;" OwnerUserId="3721" LastEditorUserId="28837" LastEditDate="2021-02-28T17:48:51.183" LastActivityDate="2021-02-28T17:48:51.183" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="26957" PostTypeId="2" ParentId="26910" CreationDate="2016-04-15T16:10:09.390" Score="0" Body="&lt;p&gt;Yes.  What your question boils down to is, essentially:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Ignoring power input, can an electrical engine produce equivalent output to a jet engine within the size and weight of that jet engine?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is the power to weight ratio of a jet engine greater than electric engines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is the power to volume ratio of a jet engine greater than electric engines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Power-to-weight_ratio#Electric_motors.2FElectromotive_generators&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Power-to-weight_ratio#Electric_motors.2FElectromotive_generators&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GE90-115B Brayton turbofan jet engine used on the Boeing 777 has a power to weight ratio of 10.0 kW/kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An electric motor made for aviation, the EMRAX268, has significantly lower power, but attains 10.0 5kW/kg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some will be concerned about whether the motors can scale up but as can be seen in the electric vehicle industry fast electric cars are readily available, and the size and volume of of just the motor and its required components (cooling, control) is smaller and lighter than the gas engines for those vehicles that can compete in terms of acceleration and top speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even more telling is that the electric motor and its components are not only lighter and smaller, but they are cheaper as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only limiting factor to electric aviation is the power source, and as a step forward every major manufacturer is already designing hybrid electric planes.  As powerful as jet engines are, they are still not as fuel efficient (and thus emissions efficient) as they could be.  A jet fuel powered generators powering electric engines may be available in the market within a decade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These hybrid planes wouldn't be possible if the electric engines couldn't hold their own in size, weight, and power relative to a jet engine.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2016-04-15T16:10:09.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26958" PostTypeId="1" AcceptedAnswerId="26962" CreationDate="2016-04-15T16:31:35.623" Score="10" ViewCount="1004" Body="&lt;p&gt;I'm a student pilot studying right-of-way and confused about the landing provisions. Right-of-way is determined first by aircraft category, and then by position. That makes sense.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But the last provision, on final, says the lower aircraft has the right away. Does that mean that the lower aircraft regardless of the category has the right-of-way, or does the lower aircraft only have the right-of-way when they are in the same category?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For instance, if a glider was on final but high, and a Cessna 172 was on final but lower/closer, who would have the right-of-way?&lt;/p&gt;&#xA;" OwnerUserId="14505" LastEditorUserId="19" LastEditDate="2016-10-14T14:19:28.393" LastActivityDate="2016-10-14T14:19:28.393" Title="What are the rules for right-of-way on final approach: by aircraft category or only by height?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26959" PostTypeId="1" CreationDate="2016-04-15T16:33:16.117" Score="15" ViewCount="469" Body="&lt;p&gt;I know that when manoeuvring on the ground, asymmetric thrust is often used, for example to assist in turns when taxiing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there other circumstances in normal operations which might call for the use of deliberate asymmetric thrust in manoeuvring?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am specifically not asking about emergency or other abnormal ops, flight testing or auto-throttle operation.  I could rephrase the question as &quot;in day-to-day ops of flying an multi-engine commercial jet, is asymmetric thrust ever used to manoeuvre the aircraft when not on the ground?&quot;.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="1696" LastEditDate="2018-04-09T19:43:17.270" LastActivityDate="2018-04-10T01:48:13.800" Title="On commercial jets, is asymmetric thrust used as part of normal operations?" Tags="&lt;airliner&gt;&lt;airline-operations&gt;&lt;multi-engine&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26960" PostTypeId="1" AcceptedAnswerId="26965" CreationDate="2016-04-15T16:38:58.523" Score="16" ViewCount="2386" Body="&lt;p&gt;This image of a LC-130 taking off from a snow runway shows that in addition to wheels on the landing gear, it's also been equipped with skis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f1/LC130-Takeoff-Greenland.swn.jpg&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f1/LC130-Takeoff-Greenland.swn.jpg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/f/f1/LC130-Takeoff-Greenland.swn.jpg&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: Wikimedia Commons.&lt;br&gt;We're getting a lot of use out of this image lately!&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How do these skis get stowed when the gear retract? &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do the skis become part of the gear door?&lt;/li&gt;&#xA;&lt;li&gt;Is there enough room in the gear bay for the skis?&lt;/li&gt;&#xA;&lt;li&gt;Are modifications to the gear bays necessary to accommodate the skis?&lt;/li&gt;&#xA;&lt;li&gt;Is there any modification necessary to the movement of the gear to accommodate the skis? (i.e. some gear rotate as they stow. I'm not sure if the C-130s do or not.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2016-04-15T16:54:59.313" LastActivityDate="2016-04-15T18:59:00.777" Title="How are skis stowed on retractable gear aircraft?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26961" PostTypeId="2" ParentId="1776" CreationDate="2016-04-15T16:54:11.640" Score="1" Body="&lt;p&gt;All the above answers are wrong. A POH is a 'kind' of AFM. All aircraft must have an approved AFM. Before 1978 this could be anything (owners manual, POH, etc.). After 1978 GAMA (General Aviation Manufacturers Association) decided to standardize the AFM around the POH format. The name POH stuck… but it is still a kind of AFM.&lt;/p&gt;&#xA;" OwnerUserId="14506" LastEditorUserId="21763" LastEditDate="2021-05-21T08:27:28.230" LastActivityDate="2021-05-21T08:27:28.230" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="26962" PostTypeId="2" ParentId="26958" CreationDate="2016-04-15T17:26:08.590" Score="11" Body="&lt;p&gt;The C172 has right of way, it's lower. The rules are in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1113&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.113&lt;/a&gt; and the only place where categories are mentioned is in 91.113(d), which is specifically about &lt;em&gt;converging&lt;/em&gt; traffic at &quot;approximately the same altitude&quot;. For &lt;em&gt;landing&lt;/em&gt; traffic, the lower aircraft has the right of way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;People spend lots of time and energy discussing who has right of way on final, what &quot;on final approach&quot; really means, if it's OK to &lt;a href=&quot;https://aviation.stackexchange.com/q/25661/62&quot;&gt;cut off&lt;/a&gt; a faster (or slower) aircraft, if an aircraft on a 5-mile final prevents other aircraft in the pattern from landing etc. But the discussion often becomes a bit academic: practically speaking the point is to be safe, not create any problems, and not cause other aircraft to go around or maneuver to avoid you. Think of it like pulling out of a side street in your car: if another car is coming then you shouldn't cause him to brake hard or swerve to avoid you.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-04-15T18:12:42.580" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26964" PostTypeId="2" ParentId="26960" CreationDate="2016-04-15T18:17:16.777" Score="8" Body="&lt;p&gt;The LC-130 is heavily modified but when the skis retract, they stay outside the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_LC-130&quot; rel=&quot;noreferrer&quot;&gt;Lockheed LC-130 From Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The aircraft are equipped with retractable skis that allow the aircraft to land on snow and ice as well as on conventional runways.&quot; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.litech.org/~lutchana/downsouth/South-Pole-Trip/South-Pole-Trip.html&quot; rel=&quot;noreferrer&quot;&gt;The skis retract until they are almost flush&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;The skis retract until they are almost flush with the fuselage during flight, and they can also retract the skis and deploy regular wheels.&quot; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;LC-130 in flight&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QE94f.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QE94f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;source: &lt;a href=&quot;http://www.nzff.org/viewtopic.php?t=13402&amp;amp;p=8272160&quot; rel=&quot;noreferrer&quot;&gt;http://www.nzff.org/viewtopic.php?t=13402&amp;amp;p=8272160&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VuSHq.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VuSHq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;source: &lt;a href=&quot;http://www.vaq34.com/lc130list/c-130h.htm&quot; rel=&quot;noreferrer&quot;&gt;http://www.vaq34.com/lc130list/c-130h.htm&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-15T18:59:00.777" LastActivityDate="2016-04-15T18:59:00.777" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26965" PostTypeId="2" ParentId="26960" CreationDate="2016-04-15T18:17:24.900" Score="18" Body="&lt;p&gt;The skis partially retract. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an image of one with the gear retracted:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Oz5Sc.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Oz5Sc.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;Source: &lt;a href=&quot;http://www.uwosh.edu/faculty_staff/hiatt/Research/mcmurdo.html&quot; rel=&quot;noreferrer&quot;&gt;UW Oshkosh&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do the skis become part of the gear door?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;From looking at the images with the gear deployed and then the ones with the gear stowed, it appears that the skis do form the gear doors. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there enough room in the gear bay for the skis?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, the skis are not retracted into the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Are modifications to the gear bays necessary to accommodate the skis?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It doesn't appear to be, but there may be modifications to the retraction mechanism to allow the wheels to be stowed while the ski is still outside of the aircraft. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there any modification necessary to the movement of the gear to accommodate the skis? (i.e. some gear rotate as they stow. I'm not sure if the C-130s do or not.)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It does appear that there is, yes. The ski's can be deployed without the wheels touching the ground, or the skis can remain retracted and the wheels extended for paved runway operations. Take a look at these two photos:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BsQV5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BsQV5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;Source: &lt;a href=&quot;https://www.pinterest.com/pin/399976010631389685/&quot; rel=&quot;noreferrer&quot;&gt;PIntrest&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice how the wheels are on top of the skis? Now take a look at this one:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tiJvn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tiJvn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;Source: &lt;a href=&quot;http://www.flyian.net/aircraft/airshow/2012psm/c130ski.htm&quot; rel=&quot;noreferrer&quot;&gt;FlyIan.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You notice that the skis are still retracted and the wheels are extended through the skis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to know what was modified for the gear doors, take a look at this image of a &quot;normal&quot; C-130:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EN0JC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EN0JC.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;Source: &lt;a href=&quot;https://www.youtube.com/watch?v=VUMHj4CReU8&quot; rel=&quot;noreferrer&quot;&gt;YouTube&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice how the rear gear door goes a quarter way up the &quot;pontoon&quot;? The version with skis has a fixed panel that replaces the gear door and matches up with the profile of the skis to reduce drag.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-15T18:45:50.403" LastActivityDate="2016-04-15T18:45:50.403" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26967" PostTypeId="1" AcceptedAnswerId="26972" CreationDate="2016-04-15T18:56:10.260" Score="8" ViewCount="1775" Body="&lt;p&gt;At LAX, planes (usually) take off from east to west. On the west end of the runways there are dark tire marks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the cause of thesey tire marks? Failed take offs? Late landings? Something else?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LjARn.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LjARn.png&quot; alt=&quot;runway marks on northwest LAX runway&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://www.google.com/maps/@33.9466778,-118.4313842,1382m/data=!3m1!1e3&quot; rel=&quot;noreferrer&quot;&gt;Google Maps of LAX&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7129" LastEditorUserId="13197" LastEditDate="2016-04-16T21:06:31.650" LastActivityDate="2016-04-16T21:06:31.650" Title="What is the cause of tire marks at the extreme ends of runways?" Tags="&lt;landing&gt;&lt;takeoff&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26968" PostTypeId="1" AcceptedAnswerId="26971" CreationDate="2016-04-15T19:01:31.193" Score="33" ViewCount="3079" Body="&lt;p&gt;In the Southwest corner of LAX (at the intersection of Imperial Highway and Pershing Dr.) there is a strange looking area that appears to have some abandoned airplane parts. Also, it looks like a road-striper had a good time one day doing donuts around one of the artifacts. Anyone familiar with this area and what it is used for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Waqrf.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Waqrf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://www.google.com/maps/place/33%C2%B055&amp;#39;55.9%22N+118%C2%B025&amp;#39;42.0%22W/@33.9322043,-118.4290073,366m/data=!3m2!1e3!4b1!4m2!3m1!1s0x0:0x0&quot;&gt;Google Maps&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="7129" LastEditorUserId="824" LastEditDate="2017-02-12T00:16:03.353" LastActivityDate="2017-02-12T00:16:03.353" Title="Southwest corner of LAX has peculiar airplane parts, what is this area?" Tags="&lt;runways&gt;&lt;firefighting&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="26969" PostTypeId="2" ParentId="26967" CreationDate="2016-04-15T19:03:55.810" Score="5" Body="&lt;p&gt;That would be caused by the tires which are not rolling start rubbing away on the runway on touchdown. Since the tires are not moving, it is going to &quot;scrape&quot; on the runway and leave a mark. This problem is addressed by &lt;a href=&quot;https://aviation.stackexchange.com/questions/3702/why-are-aircraft-tires-not-pre-spun-prior-to-landing-to-preserve-them/3705#3705&quot;&gt;this question&lt;/a&gt;. It also produces some smoke as you can see in the image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EI8kq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EI8kq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;http://www.avionale.com/2011/10/airbus-a340-500-hard-and-smokey-landing.html/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Same thing happens when a car spins on the road.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/mX4J8.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mX4J8.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find the source for this.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-15T19:10:36.280" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26970" PostTypeId="2" ParentId="26968" CreationDate="2016-04-15T19:06:54.527" Score="36" Body="&lt;p&gt;It is an aircraft fire simulator. They use it for training emergency response personnel and vehicles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see them training on one in this &lt;a href=&quot;https://www.youtube.com/watch?v=1bS6mb2FgEM&quot;&gt;YouTube video&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/vcRbu.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/vcRbu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br/&gt;&#xA;Source: &lt;a href=&quot;https://www.leipzig-halle-airport.de/en/company/about-us/fire-training/aircraft-rescue-and-fire-fighting-976.html&quot;&gt;Leipzig Halle Airport&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-04-15T19:06:54.527" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26971" PostTypeId="2" ParentId="26968" CreationDate="2016-04-15T19:09:25.060" Score="30" Body="&lt;p&gt;All major airports have practice fire fighting facilities equipped with dummy aircraft that are made of steel so they don't burn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the dummy steel aircraft, they will often use retired aircraft to use for familiarization and evacuation training.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mvMgQ.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mvMgQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &#xA;&lt;a href=&quot;http://news.hjnews.com/news/cache-valley-firefighters-practice-putting-out-aircraft-fires/article_11cb912c-d018-11df-920b-001cc4c002e0.html&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/OGMQ2.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/OGMQ2.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://australianaviation.com.au/2013/04/new-fire-training-ground-for-melbourne-airport/&quot;&gt;Source&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/coVxH.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/coVxH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.airport-data.com/aircraft/photo/000936595.html&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="13197" LastEditDate="2016-04-15T20:10:45.573" LastActivityDate="2016-04-15T20:10:45.573" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26972" PostTypeId="2" ParentId="26967" CreationDate="2016-04-15T19:13:23.917" Score="14" Body="&lt;p&gt;The marks are left by the tires of landing planes when they touch down -- that is, ordinary routine landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wheels of a landing aircraft do not start rotating &lt;em&gt;before&lt;/em&gt; they hit the runway -- so right at the moment of touchdown, the wheels will at first &lt;em&gt;skid&lt;/em&gt; along the runway surface until the friction between tires and runway has delivered enough angular momentum to the tire to spin it up so it matches the ground speed of the landing plane. Once that happens, the wheel will roll normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This skidding causes the skid marks you have observed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if the runway is &lt;em&gt;usually&lt;/em&gt; used in the east-to-west direction, there are still enough days where landings are from the west that both ends of the runway will collect tire marks. How many days that are doesn't really influence how black the runway gets, only how long it can go between having the rubber buildup cleaned off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the few airports that are &lt;em&gt;really&lt;/em&gt; only used in one direction (such as the famous Princess Juliana Intl Airport at St. Maarten, which does not even have charted approaches from the east due to terrain obstacles) you will find the tire marks only at the touchdown end of the runway.&lt;/p&gt;&#xA;" OwnerUserId="959" LastEditorUserId="959" LastEditDate="2016-04-15T20:38:46.063" LastActivityDate="2016-04-15T20:38:46.063" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26973" PostTypeId="1" AcceptedAnswerId="27017" CreationDate="2016-04-15T19:54:11.583" Score="6" ViewCount="1038" Body="&lt;p&gt;Tried looking for a definition on wikipedia for a G-Check. The wikipage only mentions A,B,C,D checks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any ideas what a G-check exactly is? I think I found an article stating it is a 7500 hr major inspection. What is considered a major inspection relative to a minor?&lt;/p&gt;&#xA;" OwnerUserId="2960" LastEditorUserId="13197" LastEditDate="2016-04-16T21:08:01.250" LastActivityDate="2016-04-17T19:14:46.663" Title="What is a G-Check and what are the differences relative to other checks?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26974" PostTypeId="2" ParentId="26906" CreationDate="2016-04-15T19:58:12.083" Score="12" Body="&lt;p&gt;Another option might be the Soviet Ekranoplan: these are aircraft that use the ground effect to fly just off a surface of water.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example we might have the Lun-class (73m):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BWdYa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BWdYa.jpg&quot; alt=&quot;MD-160 Ekranoplan&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;or the experimental Caspian Sea Monster (92m):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2w5gM.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2w5gM.jpg&quot; alt=&quot;Caspian Sea Monster&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sadly neither of these are flying any longer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(source: Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_effect_vehicle&quot; rel=&quot;noreferrer&quot;&gt;Ground effect vehicle&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lun-class_ekranoplan&quot; rel=&quot;noreferrer&quot;&gt;Lun-class ekranoplan&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="14510" LastEditorUserId="4506" LastEditDate="2016-04-17T03:53:16.107" LastActivityDate="2016-04-17T03:53:16.107" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26976" PostTypeId="2" ParentId="26954" CreationDate="2016-04-15T22:12:19.787" Score="5" Body="&lt;p&gt;It seems to be a C-12 or C-13 &lt;a href=&quot;https://aviation.stackexchange.com/questions/16910/what-is-the-difference-between-sensitive-and-non-sensitive-altimeters&quot;&gt;sensitive&lt;/a&gt; altimeter (&lt;em&gt;SA&lt;/em&gt;) from Kollsman Instrument Division / Square D Company, manufactured circa 1940:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qbbcU.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qbbcU.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://www.liveauctioneers.com/item/1453586_vint-kollsman-instrumentsquare-d-co-altimeter&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only difference seems to be the marking &quot;ALTITUDE&quot; replaced by &quot;SA-91&quot;. As this is the 39th in the series, this could be the initial marking, later replaced by the more standard one. I don't see what could be &quot;91&quot; for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Kollsman window is black (as commented) because the setting dial has been turned past maximum pressure reference, as indicated by the bug between 7 and 8. The window value and this bug are linked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The brown color seem to be related to &lt;a href=&quot;https://en.wikipedia.org/wiki/Phosphorescence&quot; rel=&quot;nofollow noreferrer&quot;&gt;phosphorescent&lt;/a&gt; markings and needles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-12 has apparently many variants, likely designed on demand, especially for the USAF, like this one with alternate colors for the marks:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rAvuy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rAvuy.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;C-12 manufactured by &lt;em&gt;C.G. Conn Ltd.&lt;/em&gt;, (&lt;a href=&quot;https://www.etsy.com/listing/180016687/c-g-conn-c-12-sensitive-altimeter-flight?utm_source=Pinterest&amp;amp;utm_medium=PageTools&amp;amp;utm_campaign=Share&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.tumblr.com/search/c.g.%20conn&quot; rel=&quot;nofollow noreferrer&quot;&gt;C.G. Conn Ltd.&lt;/a&gt; is a music instruments company (saxophones), but at war time they provided aircraft instruments to the USAF (&lt;a href=&quot;https://i.imgur.com/ybnj7I2.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying on instruments&lt;/a&gt; finally explained!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kollsman published handbooks about their instruments. Here is one from 1938. It doesn't cover this model of altimeter, but can be helpful though:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/l4i6B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/l4i6B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://babel.hathitrust.org/cgi/pt?id=mdp.39015011832311;view=2up;seq=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-16T23:54:06.907" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="26977" PostTypeId="2" ParentId="26967" CreationDate="2016-04-15T22:41:05.757" Score="2" Body="&lt;p&gt;The reason for the marks is that this is the touchdown zone of the runway. The aiming point for landing is the 1,000' marker, the pair of solid white stripes. This is where the ILS glideslope and visual landing aids are aligned. Planes to float past the touchdown marker because of the flair at the end of landing so the densest tire marks tend to be at and just beyond the marker.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-04-15T22:41:05.757" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26978" PostTypeId="2" ParentId="26954" CreationDate="2016-04-15T23:42:03.173" Score="0" Body="&lt;p&gt;Of interest is the serial number on the face of the instrument.  Yes it appears to be the Kollsman type but lacks the barometric readout in the &quot;Kollsman window&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I suspect that you have an early prototype of the Kollsman.  At least that is my best guess.  I'm not an expert on antique altimeters but just a knowledgeable pilot and aviation enthusiast.&lt;/p&gt;&#xA;" OwnerUserId="13424" LastActivityDate="2016-04-15T23:42:03.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26980" PostTypeId="2" ParentId="26944" CreationDate="2016-04-16T02:13:50.857" Score="9" Body="&lt;p&gt;In a &lt;a href=&quot;http://www.google.com/url?q=http://www.atag.org/component/downloads/downloads/59.html&amp;amp;sa=U&amp;amp;ved=0ahUKEwj8l7Pb6pHMAhUCt4MKHdl_Cq4QFggNMAE&amp;amp;sig2=Ds9tu0AftqLoJGZ5jBVbFQ&amp;amp;usg=AFQjCNHkeD86BwJAFyRfFkR_waEq951NAw&quot; rel=&quot;noreferrer&quot;&gt;paper&lt;/a&gt; written in 2010 several factors are laid out in addition to aircraft design that have improved fuel efficiency and cost over the years and possible improvements in the future. Several areas were highlighted.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Routing&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Opening up more airspace by more efficient usage increases efficiency.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is estimated that up to 8% of all aviation fuel is wasted as a result of the inefficient routes aircraft have to fly.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The paper cites flight management systems on newer aircraft as contributing toward efficiencies in routing.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;On certain oceanic routes, flight control computers are automatically plotting their own, most efficient routings with some impressive results. One airline, for example, has been working with Australian air traffic management to save almost 10 million litres of jet fuel and 772 hours of f light time in five years. It does this by exploiting the jet streams and tailwinds in the Indian Ocean.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The following charts show projected savings for implementation of NextGen air traffic systems in the US and SESAR in Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y9A06.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y9A06.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yY0U8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yY0U8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Continuous climb&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Being able to climb continuously to cruise altitude can save on fuel.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A number of airports and airlines are trialling the use of so-called ‘green departures’, allowing pilots to take-off and climb to the optimal cruising altitude in one smooth, continuous ascent. This is   in contrast to the traditional method of climbing to the cruising altitude in several steps. By using this new departure method at one airport alone, some 10,000 tonnes of fuel and 32,000 tonnes of carbon dioxide were saved in one year alone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Continuous descent&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Similarly to climbing, fuel can be saved by avoiding stepped approaches.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In trials, fuel savings of up to 40% during the approach phase have been demonstrated. This equates to between   CDO [continuous descent operations] vs stepped approach 50 and 150kg of fuel depending on the level at which CDO is commenced and the aircraft type. Up to 150,000 tonnes of fuel a year, or 500,000 tonnes of CO2, could be saved in Europe alone if CDO approaches were more widely adopted. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Satellite based approaches and departures&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Using RNAV procedures help expedite aircraft through the airport environment.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Using satellite-based and on-board precision navigation systems such as “Area Navigation” and “Required Navigation Performance” capabilities allows ANSPs [Air Navigation Service Providers] to re-design airspace and procedures so aircraft can fly automatic fuel-saving routes into and out of the busiest airports in the world. These new departure routes have reduced departure delays of more than 2.5 minutes per flight at one airport since their introduction. Annual fuel savings are estimated at $34 million, with cumulative savings of 105 million from 2006 through 2008.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Ground handling&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Fuel is saved by using single engine taxi or tugs where appropriate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another place more efficiency can be garnered is by installing ground electrical power to reduce APU usage.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;studies suggest that up to 85% of APU use can be reduced if groundbased electrical power systems are available, cutting the fuel bill, per gate, by $100,000 a year.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Reducing delays&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Another costly problem is flight delays. Aircraft end up sitting on the ramp or taxiway burning fuel waiting for clearances.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In the United States alone, the cost of burning fuel on the ground as a result of delays to the airline schedule amounted to over $5 billion in 2008 alone.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;h2&gt;Conclusion&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The following graph represents the potential fuel savings projected into the future broken down by technological improvements in aircraft design and fuels, operational issues such as ground handling and delays, and infrastructure such as airspace availability and routing. Of course any future projection is speculative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/rLZrs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rLZrs.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-04-16T02:13:50.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26982" PostTypeId="1" AcceptedAnswerId="26994" CreationDate="2016-04-16T08:21:27.930" Score="5" ViewCount="767" Body="&lt;p&gt;In practice, they are simply available online and mostly free. &#xA;Alternatively, anyone may purchase an ADS-B receiver to monitor the surrounding air traffic and air-band radio to listen to ATC. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering if there are regulations, similar to restriction of the use of GPS tracker and phone call recording? Or is it simply assumed that, for public safety, anyone conducting a flight is automatically presumed to volunteer the information of flight path and air conversation to the public?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="13197" LastEditDate="2016-04-16T21:09:58.543" LastActivityDate="2016-04-16T23:40:36.233" Title="Are ATC radar tracking records and audio recordings considered legally public?" Tags="&lt;faa-regulations&gt;&lt;regulations&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="26983" PostTypeId="1" AcceptedAnswerId="26984" CreationDate="2016-04-16T10:54:52.303" Score="5" ViewCount="761" Body="&lt;p&gt;I am doing my college project in which air is first accelerated to supersonic  conditions in a nozzle. Then it is added into slow moving subsonic air. I see that my flow becomes supersonic and then subsonic but I don't see a shockwave. All this is done on Fluent using various 2 equation models. &lt;/p&gt;&#xA;" OwnerUserId="13652" LastActivityDate="2016-04-16T12:34:38.207" Title="Can a flow which is initially supersonic, become subsonic without a shock wave?" Tags="&lt;supersonic&gt;&lt;shock-waves&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26984" PostTypeId="2" ParentId="26983" CreationDate="2016-04-16T12:26:32.610" Score="5" Body="&lt;p&gt;Yes, it is possible . The shockless transition from supersonic to subsonic. It has been tested both experimentally and numerical solution. Read &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/3.51438&quot; rel=&quot;noreferrer&quot;&gt;this AIAA Paper&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in your case I would suggest you to be a bit cautious and recheck your mesh and boundary condition in CFD solver.&lt;/p&gt;&#xA;" OwnerUserId="14332" LastEditorUserId="4197" LastEditDate="2016-04-16T12:34:38.207" LastActivityDate="2016-04-16T12:34:38.207" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26985" PostTypeId="5" CreationDate="2016-04-16T12:48:21.253" Score="0" Body="&lt;p&gt;The Antonov An-225 Mriya is a single commercial cargo airplane built by Antonov as the transport for the Soviet Union's version of the Space Shuttle. It is the largest airplane in the world with a length of 276 feet/84 metres.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-16T12:48:21.253" LastActivityDate="2016-04-16T12:48:21.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26986" PostTypeId="4" CreationDate="2016-04-16T12:48:21.253" Score="0" Body="For questions about the 6-engined cargo airplane created by Antonov." OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-04-16T12:48:21.253" LastActivityDate="2016-04-16T12:48:21.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26987" PostTypeId="1" AcceptedAnswerId="26991" CreationDate="2016-04-16T13:06:02.880" Score="6" ViewCount="2565" Body="&lt;p&gt;I was having a discussion with my friend about equilibrium condition in flight:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Scenario:&#xA;While going in straight and level flight, say I reduced my airspeed by 30 mph. &#xA;At the same time keeping the airplane's attitude strictly the same as before &#xA;(doing whatever it takes to keep the nose where it was before).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reducing the speed means, the aircraft develops less lift: Aircraft is supported by less pounds of lift force (meaning which lift is less than weight)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happens next? (imagining that pilot does not nose down)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My take:&#xA;1. Since weight &gt; lift, aircraft drops attitude and falls like a stone that was dropped in midair unless the nose is down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My friend says: &#xA;2.  The airplane finds new lift. This sinking motion creates lift &#xA;for aircraft. But it will not maintain straight level flight but descends. It will be a steady descent not accelerating descent. (not like a stone falling out of sky). He says this is called power descent&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;1) Who is right here&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) If my friend is right, if aircraft can find lift after it descends (which means it found equilibrium) , why can not it maintain straight and level flight. And what exactly caused it to find new lift? Has angle of attack changed?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="13197" LastEditDate="2016-04-16T20:13:35.863" LastActivityDate="2016-04-16T21:28:59.857" Title="What happens during a powered descent?" Tags="&lt;lift&gt;&lt;angle-of-attack&gt;&lt;descent&gt;&lt;weight&gt;" AnswerCount="5" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26988" PostTypeId="2" ParentId="26987" CreationDate="2016-04-16T13:21:31.940" Score="0" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Your friend is right. The airplane is basically a glider in that scenario and gliders still fly even though they are mostly unpowered of themselves, motor-gliders excepted.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The airplane can find lift as it descends because of the gravitational potential energy it has. However, the lift produced is less than the weight of the aircraft, due to drag and the Laws of Thermodynamics (The First and Second if I am not mistaken) so the airplane starts to descend. The lift is caused by the airspeed as the potential energy of the &quot;dropping&quot; plane converts to kinetic energy and thus airspeed and lift along with it. You could find net positive lift by flying into a rising thermal like a glider does to bring it higher.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-04-16T13:21:31.940" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26989" PostTypeId="2" ParentId="26987" CreationDate="2016-04-16T14:00:06.460" Score="5" Body="&lt;p&gt;Note: This answer refers to the initial question as asked by user2927392. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who is right depends on the initial speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift  is determined by two parameters as long as the wing geometry stays unchanged, &lt;a href=&quot;https://aviation.stackexchange.com/questions/22630/what-is-the-relation-between-the-lift-coefficient-and-the-angle-of-attack&quot;&gt;angle of attack&lt;/a&gt; and dynamic pressure (which is the product of air density and speed squared). The slower plane will initially develop less lift and start to descend, which in turn will increase the angle of attack such that the initial lift is regained. Since you want to maintain the attitude of the aircraft, its sinking motion will mean that the airflow comes in more from below. Note that we speak of very small angle changes - just a few degrees normally.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now much depends on how close the aircraft was to its minimum speed. As angle of attack increases, the flow will have trouble to follow the steeper contour of the wings and &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055#5055&quot;&gt;start to separate&lt;/a&gt;. If this separation grows, it will limit the lift the wings can produce. Now we have two cases:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;If the initial airspeed was higher than minimum airspeed + 30 mph, your friend is right. The aircraft will settle at a new angle of attack and will compensate the missing thrust with a &lt;a href=&quot;https://aviation.stackexchange.com/questions/26327/paper-airplane-physics/26336#26336&quot;&gt;gradual altitude loss&lt;/a&gt;, just as in SMSvonderTann's answer. Like a glider, the airplane will glide down to the ground. I assume you intend to keep the nose up by pulling on the stick: This will trim the aircraft to the lower speed and a higher angle of attack where it settles at the new equilibrium.&lt;/li&gt;&#xA;&lt;li&gt;If the initial airspeed was lower than minimum airspeed + 30 mph, you are partially right. The aircraft will &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall&quot;&gt;stall&lt;/a&gt;, lift will not suffice to find a new equilibrium, and the airplane will pitch down to pick up the missing speed, no matter how hard you pull. If you still insist on lowering the speed, you will now pull out of the dive and repeat this maneuver all over again, until the ground interfers. Note that the resulting motion is not a continuing dive, but a sequence of &quot;J&quot;-shaped curves when seen by an outside observer. The dive is less a vertical plummeting than a steep glide, similar to a rollercoaster.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;To answer your second question: Drag will slow down the aircraft unless some energy is continuously furnished by reducing altitude. Please &lt;a href=&quot;https://aviation.stackexchange.com/questions/26327/paper-airplane-physics/26336#26336&quot;&gt;read this answer&lt;/a&gt; which has a detailed explanation, albeit for paper aircraft, including some fancy math.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-16T14:42:33.777" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26991" PostTypeId="2" ParentId="26987" CreationDate="2016-04-16T14:14:58.877" Score="6" Body="&lt;p&gt;Neither of you are necessarily right, but you both have some understanding which is accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let me reiterate what you have stated, for clarity's sake. The scenario starts with the aircraft flying straight and level. Then the airspeed is reduced by 30 mph through a power reduction while the attitude is held constant. Regardless of what else happens we all recognize that this will result in some type of descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You are right in that the airplane has lost &quot;lift&quot; from the lost thrust and will thus descend. Depending on the aircraft and the starting airspeed, you might be right that the  aircraft might respond with an &lt;em&gt;uncommanded&lt;/em&gt; attitude pitch down. If that were the case, it would be due to the scenario resulting in an aerodynamic stall. However, &lt;em&gt;even if&lt;/em&gt; the aircraft were to stall it would not drop like a stone (that is, with no lift to oppose gravity), but would descend at what would still be a substantial rate of descent while still producing some lift to oppose gravity. Moreover, considering the possible entry speeds and attitudes, a stall would be unlikely in this scenario.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your friend is right in that, with sufficient airspeed and no aerodynamic stall—both of which depend on the airspeed at which the maneuver was started—this scenario will result in a descent. It would be accurate to call this a powered descent. Depending on what he means by it, your friend may not be quite right to think that any &quot;new&quot; lift would be produced by the &lt;em&gt;sinking motion itself&lt;/em&gt;, but this might be a difference of semantics. Let's explore this further.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's consider a Cessna 172 cruising straight and level at 110 mph. We then reduce the power to maintain 80 mph and hold the pitch attitude exactly where we started. In this scenario we have transitioned from cruise speed to something closer to the aircraft's best rate of climb speed. This means that we have transitioned from a high speed, high drag region of flight to a lower speed, lower drag region of flight. At the same time, by holding the aircraft's pitch attitude constant, we have changed from a low angle of attack, low coefficient of lift region of flight to a high angle of attack, high coefficient of lift region of flight. This increase in angle of attack is due to the new angle of the relative wind introduced by the aircraft's descent. The overall amount of lift doesn't change, but the way the lift is created does change. As the speed is reduced the wing's ability to create lift (expressed by the coefficient of lift) increases with the increase in angle of attack. Thus the lift doesn't change, but the lift is now due more to the angle of attack than the airspeed. If this is what your friend means by &quot;new&quot; lift introduced by the sinking motion, then he is right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this &quot;new&quot; lift must be understood to be due to the angle of attack change, not an increase in net speed (kinetic energy). The lift isn't actually changing, merely the way in which it is created—angle of attack as opposed to speed. However, if the scenario were different and we allowed the aircraft to pitch down as we reduced power, the aircraft would pitch down to maintain about 110 mph, and the wing's coefficient of lift would change very little as the airspeed and angle of attack remained relatively constant.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-04-16T14:41:33.583" LastActivityDate="2016-04-16T14:41:33.583" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="26992" PostTypeId="2" ParentId="26987" CreationDate="2016-04-16T14:34:25.327" Score="0" Body="&lt;p&gt;Let's generalized where the airspeed is any X, where X &gt;&gt; 30 kts and that X &amp;lt;&amp;lt; Mach 1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were level and you reduce the power and touch nothing else, the aircraft will descend and accelerate until it reaches roughly X again; the point of equilibrium between angle of attack and airspeed. The aircraft will descend with roughly the same airspeed as what you started with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This effect is critical in landing. Adding power reduces the descent and reducing power increases the descent; without significantly and over the long term changing the airspeed.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-04-16T14:34:25.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26993" PostTypeId="2" ParentId="26987" CreationDate="2016-04-16T21:28:59.857" Score="-2" Body="&lt;p&gt;I think you (and some of the answerers) are making this way more complicated than it needs to be. These are the facts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(1) If you are in level flight and you reduce power, you will descend. This is the normal way to descend.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(2) If you are in level flight and you push the yoke forwards, you will go faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(3) If you are in level flight and you pull the yoke back, you will slow down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That is all there is to it. Don't make it too complicated.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-16T21:28:59.857" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="26994" PostTypeId="2" ParentId="26982" CreationDate="2016-04-16T21:49:41.273" Score="7" Body="&lt;p&gt;The FAA is only authorized by congress to regulate FLIGHT, not radio communications.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radio communications are regulated by the FCC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both of these agencies have no power to make laws. They can make only &quot;regulations&quot;. In the United States, according to the Constitution, laws can only be made by Congress or the legislatures of the several states.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The position of the FCC is that it is legal for any person to monitor and record any radio transmission that they wish. The only exception to this is listening to private telephone conversations or encrypted military transmissions. The Federal law that prohibits this, &lt;em&gt;explicitly exempts maritime and aeronautical transmissions&lt;/em&gt;. This is the language:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;18 USC § 2511 (2)(g.ii.IV) It shall not be unlawful under this chapter&#xA;  or chapter 121 of this title for any person to intercept any radio&#xA;  communication which is transmitted by any marine or aeronautical&#xA;  communications system;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Therefore, by United States federal law it is explicitly allowed and permitted for anyone to monitor and record maritime or aeronautical communications.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-04-16T23:40:36.233" LastActivityDate="2016-04-16T23:40:36.233" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="26998" PostTypeId="1" CreationDate="2016-04-17T03:01:45.430" Score="3" ViewCount="843" Body="&lt;p&gt;Here is a rendering of the original Boeing 787 design:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://qph.is.quoracdn.net/main-qimg-e9fed2323fb50190a219714e50d32c91?convert_to_webp=true&quot; alt=&quot;787 original design&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plane built can be seen here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://images.franchiseherald.com/data/thumbs/full/3042/570/0/0/0/boeing-787-dreamliner.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;787 as built http://images.franchiseherald.com/data/thumbs/full/3042/570/0/0/0/boeing-787-dreamliner.jpg&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why were the shapes of the nose, tailfin and tailcone changed during the design process?&lt;/p&gt;&#xA;" OwnerUserId="2923" LastEditorUserId="3313" LastEditDate="2016-04-17T15:02:05.763" LastActivityDate="2016-04-17T15:48:07.577" Title="Why did the Boeing 787 design change shape from the original renderings to the actual design?" Tags="&lt;aircraft-design&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="26999" PostTypeId="1" AcceptedAnswerId="27001" CreationDate="2016-04-17T04:31:09.607" Score="16" ViewCount="12481" Body="&lt;p&gt;My CFI has told me that in my checkride I will begin a planned cross country flight and will be diverted to another airport shortly into the flight. My question is, how do I effectively plan for this? I am unable to get for example NOTAMS, weather predictions, runways and their lengths etc. for the airport I'm going to (because I don't know what it is)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I have read I will be acting as PIC on the checkride and as such I don't feel like I can comfortably satisfy CFR 91.103 when I don't even know where I will be flying to.&lt;/p&gt;&#xA;" OwnerUserId="14527" LastEditorUserId="19" LastEditDate="2016-07-11T14:32:24.543" LastActivityDate="2016-07-13T16:12:31.150" Title="How do I plan for my PPL checkride which will involve a diversion?" Tags="&lt;flight-planning&gt;&lt;checkride&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27000" PostTypeId="1" CreationDate="2016-04-17T06:01:33.333" Score="5" ViewCount="99" Body="&lt;p&gt;People often refer to the four forces in navigation as weight, lift, thrust and drag. Are there separate names for the forces acting upon the side of a craft? &lt;/p&gt;&#xA;" OwnerUserId="9172" LastEditorUserId="1467" LastEditDate="2016-04-17T08:39:59.580" LastActivityDate="2016-04-17T08:39:59.580" Title="What are the names of the forces acting upon the side of a vessel?" Tags="&lt;flight-controls&gt;&lt;navigation&gt;&lt;terminology&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27001" PostTypeId="2" ParentId="26999" CreationDate="2016-04-17T06:16:02.563" Score="25" Body="&lt;p&gt;This thread should be a great source of tips and tricks :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way to think about this is to think about the purpose of being asked to divert during your checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What the examiner will be looking for is not that you have all of the information for every possible airport you might be asked to fly to.  The examiner is wanting to see that if you had to divert unexpectedly for whatever reason, that you are able to do this safely.  That's the bottom line.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to do this, you should start working on the problem during your ground planning, and for the purposes of your checkride, this will be no different to planning any other flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Plan for your alternate.  You should have charts, frequencies etc and of course, enough fuel.  Your examiner is not going to ask you to divert to somewhere when you reach your destination, it's going to be somewhere en-route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As part of any good plan, you are going to familiarise yourself with possible diversions along the route.  If you had an urgent situation (not a dire emergency where nearest available is the only choice) requiring you to divert when you were flying solo after you gained your license, where would you go?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This doesn't mean that you need every possible piece of information for every possible airport but it does mean:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Do I have enough fuel to make possible diversions?&lt;/li&gt;&#xA;&lt;li&gt;Do I have charts on board covering the areas to the left and right of my plan?   - Have I folded my charts so that it's easy to see what possible diversions there are easily?&lt;/li&gt;&#xA;&lt;li&gt;Do I have Jeppesen (or whatever) on board and is it up to date?&lt;/li&gt;&#xA;&lt;li&gt;Have I checked the METARs and NOTAMs for anything significant for those likely diversions.&lt;/li&gt;&#xA;&lt;li&gt;Do I have my E6B or other planning tool and do I know how to use it fully?&lt;/li&gt;&#xA;&lt;li&gt;Do I know what ATC agencies I would talk to along the route if I need assistance, even if flying in uncontrolled airspace?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In your notebook for the planned flight, write down the likely diversion airfields with their key details.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The list above should be part of any plan, not just for your checkride.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the key things you're going to need to figure out is &quot;how long will it take me to get to the diversion&quot;?  In order to know this, you're going to need to know the wind at the altitude you are going to be flying at. The way I handled this was to draw a circle on my chart, marked with the wind at altitude, then the corresponding ground speed already worked out on my E6B and written into the circle for each cardinal and mid-cardinal point on the compass rose.  You can glance at this little chart to instantly see that if, for example, the requested diversion needs me to fly a heading of 320, I will be doing 86 kts for an airspeed of 100 kts.  This saves you having to actually use your E6B in the cockpit to do this.  Mark off 0, 45, 90, 135 etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you think about it, doing this in planning will prepare you for any *sensible&quot; diversion you might be asked to make.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When it comes to the time of the diversion, the primary thing your examiner is looking for is do you get &quot;aviate, navigate, communicate&quot;?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second thing the examiner is looking for is &quot;can you safely divert from en-route&quot;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have planned thoroughly, and you follow aviate, navigate, communicate, then almost by definition, you will safely divert.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So your examiner suddenly says, OK, see that completely unexpected giant sandstorm ahead, you need to get down soon.  Please divert to &quot;Mark Watney- Space Pirate&quot; airport.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Avoid the single, most important thing in this whole exercise at this point.  &lt;strong&gt;Do no go into heads down mode&lt;/strong&gt;.  It's easy to do if you are unprepared.  Your head should be down for at most 15 seconds.  Do each thing one step at a time, then scan and lookout.  If you are well prepared and planned, then not going heads down will be easy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You now need 3 things immediately - everything else can come later.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What heading do I need to fly?  &lt;/li&gt;&#xA;&lt;li&gt;How long will it take me to get&#xA;there?  &lt;/li&gt;&#xA;&lt;li&gt;Can I make it?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;For the heading, grab your chart, find the airport, then take a &lt;em&gt;rough&lt;/em&gt; heading you need.  You don't, at this stage, need to be super accurate.  Within 10 or 15 degrees will be good.  The important thing is to begin flying to towards the diversion.  You can get the ruler out and refine your heading once you've got the initial diversion sorted out.  Don't forget to aviate.  Keep your head moving, keep your scan and lookout going.  When you set up for the new heading and turn on to it, remember the gross error check as you roll out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How long will it take?  Again, you don't need to be super accurate.  Grab a quick measure of the distance from the chart and your ruler.  Then look at that wind chart you prepared earlier.  Get your estimated ground speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I get there?  You should know the aircrafts' fuels consumption numbers so do the quick calculation in your head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During all of this, remember to aviate at all times.  Also, remember to conduct your normal en-route and turn check lists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it's time to communicate.  If you are in controlled airspace, let them know you've diverted then start looking for who you might need to talk to along your diversion and get the next frequencies into the box.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you are safely flying towards your destination, you can start to do some more detailed in-the-air planning to refine your estimated heading and fuel use if needed.  You can also now deal with &quot;do I have the NOTAMs and METARs&quot; I need?  It's OK not to have them all for every possible airport (you should have them for the most likely ones) because you can always call up ATC.  That's one of the reasons they are there - to help pilots dealing with unplanned contingencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember, the examiner is looking for prior planning and aviate, navigate, communicate.  If you do this, I hope that you will see that the unexpected diversion is not actually that scary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is primarily a planning exercise, not a flying exercise.  Arrive in plenty of time.  Recognise that every minute you spend planning will reduce your stress and workload in the air and aim to be ready to go, twiddling your thumbs and itching to get airborne, 15 minutes before your planned time to walk to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might notice that I've repeated myself a lot.  That's deliberate.  Prior planning and aviate, navigate, communicate it what this is all about.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck!&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-07-12T05:26:44.483" LastActivityDate="2016-07-12T05:26:44.483" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27002" PostTypeId="2" ParentId="26999" CreationDate="2016-04-17T06:16:49.523" Score="4" Body="&lt;p&gt;The answer is: you can't plan this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is done to see how you react while in flight to a non-planned diversion, and can happen anytime in real life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's used also to evaluate how you manage stressful situations, how you manage both flying the plane and searching through the documentation to find the plate of the new destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, this means you should have with you all the required maps and approach plates for all the airfields in the vicinity of the planned path (wether its paper or in an electronic device).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And even if you don't have some required information, the tester will ensure you are able to safely proceed when encountering any unexpected situation, and thats the bottom line of any pilot.&lt;/p&gt;&#xA;" OwnerUserId="8641" LastEditorUserId="8641" LastEditDate="2016-07-12T11:32:59.587" LastActivityDate="2016-07-12T11:32:59.587" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27003" PostTypeId="1" AcceptedAnswerId="27006" CreationDate="2016-04-17T08:18:10.990" Score="12" ViewCount="11111" Body="&lt;p&gt;I heard that the diffuser allows the compressed air after the inlet spike to &quot;spread out&quot;. What does this mean? If this means expansion, wouldn't it be beneficial to have it compressed before entering the compression chamber, so why would it spread out?&lt;/p&gt;&#xA;" OwnerUserId="14530" LastEditorUserId="13197" LastEditDate="2016-04-17T17:02:51.687" LastActivityDate="2019-02-25T15:45:12.013" Title="Why does the J58 engine of the SR-71 have a diffuser after the inlet spike?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;military&gt;&lt;sr-71&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27004" PostTypeId="2" ParentId="27000" CreationDate="2016-04-17T08:39:50.673" Score="5" Body="&lt;p&gt;As we engineers are extremely boring people, and given the fact that a name seems not to be available, we generally refer to them simply as &quot;side forces&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or, at least, I never encountered a different term on any of the textbooks that I have read.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-04-17T08:39:50.673" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27005" PostTypeId="1" CreationDate="2016-04-17T10:04:58.943" Score="3" ViewCount="247" Body="&lt;p&gt;On a recent passenger flight my son asked me, &quot;How come we're able to build a 737 for \$50M - \$80M with fantastic reliability and technology but can't design a PA system so that we can understand the pilot's announcements?&quot; Many are quite un-intelligible but the cabin crew announcements generally are intelligible. I didn't have a good answer. Does anyone know?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a follow on and of more concern, if pilots' microphone technique / equipment is so poor then how does air-traffic control understand them? I know there is a limited vocabulary set and that standard phrases are used to avoid mis-hearing but there must be some problems.&lt;/p&gt;&#xA;" OwnerUserId="13124" LastActivityDate="2016-04-17T16:32:11.783" Title="Pilot announcement PA quality" Tags="&lt;headset&gt;" AnswerCount="1" CommentCount="14" ClosedDate="2016-04-17T17:04:01.060" ContentLicense="CC BY-SA 3.0" />
  <row Id="27006" PostTypeId="2" ParentId="27003" CreationDate="2016-04-17T10:08:58.257" Score="15" Body="&lt;p&gt;Generally, a compressor cannot work efficiently at supersonic speed due to the shockwaves, the role of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Inlet_cone&quot; rel=&quot;noreferrer&quot;&gt;inlet cone&lt;/a&gt; and diffuser is to slow the air below Mach 1. There is a similar need for a ramjet, so that the combustion can occur within the engine and produce thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cone position and diffuser geometry are adjusted according to the airspeed. The overall shape of the diffuser is diverging.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://en.wikipedia.org/wiki/Bernoulli&amp;#39;s_principle&quot; rel=&quot;noreferrer&quot;&gt;Bernoulli's principle&lt;/a&gt;, the diffuser &lt;em&gt;decreases velocity&lt;/em&gt; and &lt;em&gt;increases pressure&lt;/em&gt; according to:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$\frac 1 \rho \; dp = - \mathrm V\;d \mathrm V$ where $\rho$ is air density.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Look at this video: &lt;a href=&quot;https://www.youtube.com/watch?v=3lkO12Fz-Q8&quot; rel=&quot;noreferrer&quot;&gt;Converging Diverging Nozzles&lt;/a&gt; for more details about how pressure and velocity are affected in a nozzle / a diffuser. Here is a summary:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N9XBJ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N9XBJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The J58 is turbojet within a ramjet. The forward section of the engine has a complex role. It adapts to a large range of speed (0 to Mach 3.2) and altitude (0 to 85,000 ft), and modifies the airflow to work either as turbojet, or as a ramjet, depending on the airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8jCJQ.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8jCJQ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Simplified adjustment of the airflow (&lt;a href=&quot;http://www.aerospaceweb.org/question/propulsion/q0175.shtml&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Actual mechanism used at different airspeed ranges in the J58:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/YXe2o.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YXe2o.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://en.wikipedia.org/wiki/File%3ASR71_J58_Engine_Airflow_Patterns.svg?wprov=sfla1&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="14897" LastEditDate="2017-04-08T23:39:08.997" LastActivityDate="2017-04-08T23:39:08.997" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27007" PostTypeId="1" AcceptedAnswerId="27011" CreationDate="2016-04-17T13:24:15.430" Score="24" ViewCount="3602" Body="&lt;p&gt;Say a major hurricane is expected to hit. Given that the weather is known beforehand, what can be done to avoid damage to the airliners sitting on the tarmac?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Fly every plane away&lt;/strong&gt; - not very economical, considering that commercial operations cease at the last minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Move all planes into a hangar&lt;/strong&gt; - a Boeing 747 takes a huge hangar to park. It may be possible to move all GA planes inside, but certainly not airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Planes are designed to interact with winds; the wings is meant to generate lift, and the sideway forces on a vertical stabilizer is meant to swing a plane around. What procedures would minimize the stress put in the airframe by the 100+km/h winds?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="13197" LastEditDate="2016-04-17T13:26:39.847" LastActivityDate="2017-09-07T21:07:47.990" Title="How are airliners secured on the ground during hurricanes?" Tags="&lt;airliner&gt;&lt;weather&gt;&lt;ground-operations&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27008" PostTypeId="2" ParentId="27005" CreationDate="2016-04-17T15:09:54.303" Score="1" Body="&lt;p&gt;Many pilots prefer to use their headset boom mic or hand mic instead of the dedicated interphone handset for PA announcements. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know why, but I know from personal experience that the dedicated interphone handset has much better PA readability. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-17T16:32:11.783" LastActivityDate="2016-04-17T16:32:11.783" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27009" PostTypeId="2" ParentId="26998" CreationDate="2016-04-17T15:48:07.577" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;https://www.quora.com/Why-did-Boeing-dumb-down-the-design-of-the-787&quot; rel=&quot;nofollow&quot;&gt;this &lt;/a&gt;answer to the same question on Quora, it was changed in order to &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;keep as many parts common with other Boeing products as possible so they could reuse old part designs, vendors and tools and let the economics of scale help bring down the costs of these parts and thus the entire airplane.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;By maintaining a greater similarity to previous Boeing products, the altered designs made the plane easier to design, build and sell, for a few reasons:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Maintaining similarity with older models made the certification process much easier and faster.&lt;/li&gt;&#xA;&lt;li&gt;Instead of having to revise, test, remodel, and debug an entirely new part, the revised design had a greater background for the engineers to work with.&lt;/li&gt;&#xA;&lt;li&gt;Completely new parts would have required more work building the machines used to construct the aircraft. Using prior designs led to reduced costs and time required in manufacturing.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Overall, the revised design made the aircraft easier and quicker to design and build which,  considering the &lt;a href=&quot;http://www.ibtimes.com/boeing-787-complete-timeline-dreamliners-legacy-failure-after-cracks-discovered-wings-1560491&quot; rel=&quot;nofollow&quot;&gt;issues and delays&lt;/a&gt; suffered by even the revised model, was a necessity.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-04-17T15:48:07.577" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27010" PostTypeId="1" AcceptedAnswerId="27014" CreationDate="2016-04-17T16:25:09.133" Score="8" ViewCount="3266" Body="&lt;p&gt;Yesterday I learned that the surface that the helicopter blades create while rotating is very similiar to a gyroscope, and thus gyroscopic precession works there as well. My question is, when the pilot moves the cyclic pitch controls forward, how does that affect the swashplate? Does it rise it in back and lower in front or does it rise on one side and lower on the other?&lt;/p&gt;&#xA;" OwnerUserId="14536" LastEditorUserId="19" LastEditDate="2016-07-11T14:34:51.450" LastActivityDate="2018-02-21T00:55:32.597" Title="How does the a movement of the cyclic control stick in a helicopter affect the swashplate?" Tags="&lt;helicopter&gt;&lt;flight-controls&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27011" PostTypeId="2" ParentId="27007" CreationDate="2016-04-17T17:07:04.130" Score="22" Body="&lt;p&gt;Looking at the hurricane manuals for a few airports, evacuating flyable aircraft to a safer location tends to be the most common choice.&lt;/p&gt;&#xA;&lt;p&gt;From the &lt;a href=&quot;http://m.bocaairport.com/sites/default/files/fileattachments/General/page/227/braa_hurricane_plan_053014.pdf&quot; rel=&quot;noreferrer&quot;&gt;Boca Raton Airport: &lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Effective with the issuance of a Storm WARNING and/or Hurricane WARNING:&lt;/p&gt;&#xA;&lt;p&gt;Relocate flyable aircraft to other geographical areas, place under suitable shelter, or secure as appropriate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Also, from the &lt;a href=&quot;http://www.miami-airport.com/pdfdoc/Hurricane_Manual.pdf&quot; rel=&quot;noreferrer&quot;&gt;Miami International Airport:&lt;/a&gt;&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Upon receipt of a Hurricane Warning, Airside Operations will:&lt;/p&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Initiate evacuation of all flyable aircraft and post Airfield Operations Senior Agents and Agents in detail to insure compliance and report results.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-17T17:07:04.130" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27012" PostTypeId="2" ParentId="16831" CreationDate="2016-04-17T17:14:47.110" Score="4" Body="&lt;p&gt;The C-17 has a special autopilot system including a component called the MILCAS-FR formation flying system by Honeywell and here is a link &lt;a href=&quot;http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Defense_Brochures-documents/MILACAS-FR_Formation_Flying_System.pdf&quot; rel=&quot;nofollow&quot;&gt;a sales brochure&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My military flight time was not in a C-17 but in my opinion once the precise formation locations were determined that achieve the fuel savings in the article it would be a simple decision to use them on any given formation flight based on the tactical situation.  The requirements of each mission would drive that decision.&lt;/p&gt;&#xA;" OwnerUserId="14451" LastEditorUserId="5517" LastEditDate="2016-04-18T12:09:12.073" LastActivityDate="2016-04-18T12:09:12.073" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27014" PostTypeId="2" ParentId="27010" CreationDate="2016-04-17T17:40:19.883" Score="6" Body="&lt;p&gt;&lt;strong&gt;Horizontal displacement: Tilt the rotor&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the rotor blades rotating around a vertical mast, the total lift vector of the rotor is vertical and the helicopter hovers. If a translation is desired, this vector must be tilted so that an horizontal component can appear. This is done by tilting the rotor disc. The rotor disc is the plane of rotation of the blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/StoHd.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/StoHd.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Rotor tilted forward: The helicopter moves forward.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Rotor tilt: Change blades pitch&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rotor disc is tilted using the lift difference between individual blades. For instance to tilt the rotor forward, each blade creates more lift when it is aft of the mast, less when it is forward of the mast, and the change is progressive between these two positions. The lift difference creates a torque moment on the mast, tilting the mast and the helicopter with it, at least this is our intuition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you mentioned, the force doesn't produce its effect instantaneously due to the gyroscopic precession. It is effective only 90° later. So the lift variation must have an advance of phase of 90°. For a forward translation, the lift is maximum when the blade is on the left, and minimum when it is on the right. The momentum is stored into the blade and released 90° later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DHmuJ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DHmuJ.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;The variation of lift is done 90° in advance.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift depends on the angle of attack of the blade. Varying the amount of lift according to the position around the mast leads to varying the AoA around the mast: Increased AoA on the left, decreased on the right. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/krSit.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/krSit.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Pitch varies according to the radial position of the blade.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Change blades pitch with the swashplate&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Changing the pitch of a blade is done using a system of swashplates. A stationary plate is oriented in space by the pilot using the cyclic stick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another plate is maintained in contact with the first one, but can turn freely with the rotor. This second plate is forced to rotate in the plane of the stationary plate, thus it oscillates constantly as it rotates. In turn, it creates an oscillation of the vertical rods (horn links). Each horn converts the rod oscillation into a pitch oscillation on the blade. The blade is now pitched according to its instantaneous radial position relative to the mast, and according to the cyclic stick command.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g8ck1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g8ck1.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;MBB Bo105, based on photo by &lt;a href=&quot;http://www.b-domke.de/AviationImages/Rotorhead.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Burkhard Domke&lt;/a&gt; (&lt;a href=&quot;http://www.b-domke.de/AviationImages/Rotorhead/7131.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Horns are linked to different angular sectors of the swashplate&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vertical rod transmits the stationary swashplate height at its current axial position. By locating the rod 90° ahead of the blade, the link takes care of the rotor precession. The mechanism is so that when the pilot pushes the cyclic forward:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The swashplate is tilted forward.&lt;/li&gt;&#xA;&lt;li&gt;When a blade moves left of the mast, its horn link measures the height of the stationary swashplate in its aft sector, where the plate is the highest.&lt;/li&gt;&#xA;&lt;li&gt;The horn is pushed by the link to the maximum, and the blade in turn gets the largest pitch angle.&lt;/li&gt;&#xA;&lt;li&gt;The situation is reversed when the blade arrives on the right. The link is in contact with the forward sector of the swashplate, where the latter is at the lowest position. The blade gets a low pitch angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HgPxK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HgPxK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(Redrawn from &lt;a href=&quot;http://avstop.com/ac/basichelicopterhandbook/ch5.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Advance for pitch order can be adjusted as required&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By adjusting the offset of the horn link which interfaces the horn and the plate, one can adjust to the exact amount of advance required for a given blade.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2017-04-08T15:05:42.700" LastActivityDate="2017-04-08T15:05:42.700" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27015" PostTypeId="2" ParentId="5090" CreationDate="2016-04-17T18:27:49.307" Score="3" Body="&lt;p&gt;Good luck finding number 1-3 on your list.  As far as I know these are proprietary data the you would have to get from Fairchild Republic.  After a career of flying fighters I never saw this data or really care about it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my opinions numbers 4 and 5 on your list are much more relevant.  What you are looking for are called EM diagrams.  EM stands for energy maneuverability and these diagrams show a scale of turn rate, turn radius, airspeed and altitude to display meanueverability at a given energy state.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using these diagrams you can find some key performance factors:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Min maneuvering airspeed - where the rate and radius slope drops off on the left of the chard showing min flying airspeed at given altitudes and wing loading&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Max instantaneous rate of turn - max possible turn rate given a certain energy state - top of the rate curve then drops off&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Max sustained rate of turn - maximum rate that can be achieved while maintaining your energy state (Ps = 0)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Corner velocity - velocity to achieve max rate at a given energy state&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Min radius - smallest radius of turn acheveable given a certain energy state&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Radius for given conditions - important to determine this when planning something like a targeting attack&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've found an A-10 EM diagram and a good Mig-21 diagram that annotates the factors I have defined above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note:  I have to giggle at your &quot;Low-Mach data is good enough for me&quot; statement.  There is no high-Mach data in an A-10.  It will top out around .6 Mach (max speed around .7)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;[&lt;img src=&quot;https://i.stack.imgur.com/8aISV.jpg&quot; alt=&quot;Mig-21 EM Diagram&quot;&gt;]&#xA;[&lt;img src=&quot;https://i.stack.imgur.com/rWzEf.jpg&quot; alt=&quot;A-10 EM Diagram&quot;&gt;]&lt;a href=&quot;https://i.stack.imgur.com/rWzEf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;2&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14451" LastEditorUserId="14451" LastEditDate="2016-04-17T18:41:55.977" LastActivityDate="2016-04-17T18:41:55.977" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27016" PostTypeId="2" ParentId="25774" CreationDate="2016-04-17T19:08:23.817" Score="2" Body="&lt;p&gt;Early jet engines were called turbojets where all flow went through the turbine. In other words there is no bypass. These are the cigar shaped engines you see in early airliners and military fighters. These types of engines are very loud and whiny and required high fuel flows to achieve the amount of thrust required.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bypass allows a few things, it provides a cooling flow of air to mix with turbine exhaust and lower the overall exit temperature so you don't overheat your nozzle. The combination of the two exhausts can also see gains in thrust for given fuel flows. One of the most significant gains of bypass flow is noise reduction by having this outer flow &quot;masking&quot; the turbine noise. This is desirable in airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two types of bypass:&lt;br&gt;&#xA;Low bypass is where there is more turbine flow than bypass flow. This is common in business jets and military fighters with a ratio of around 1.5:1 or 2.0.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High bypass where there is more bypass flow than turbine flow. This is common in modern airlines with bypass ratios upward so 10.0:1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Low bypass:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EVy4w.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EVy4w.png&quot; alt=&quot;Low bypass engine&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;High Bypass:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/C9v0p.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/C9v0p.png&quot; alt=&quot;High bypass engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In low bypass, the flow is remixed prior to exiting the nozzle, giving the cooler exit temperature typically to save the nozzle material. In a high bypass, the bypass air is allowed to flow outside of the engine after its high bypass compressor section, giving a very efficient airflow and adding to the overall thrust by moving a large volume of air outside the combustion and turbine section. This give greater fuel efficiency and much quieter engines for airplanes that can use them due to their size.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below is an example of a low bypass F-100 engine which is found on F-15 and F-16 fighters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GLnFc.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GLnFc.jpg&quot; alt=&quot;F-100 engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the GEnx high bypass engine found on 747-8 and 787.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DLT9V.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DLT9V.jpg&quot; alt=&quot;GEnx engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14451" LastEditorUserId="5517" LastEditDate="2016-04-18T12:47:11.080" LastActivityDate="2016-04-18T12:47:11.080" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27017" PostTypeId="2" ParentId="26973" CreationDate="2016-04-17T19:14:46.663" Score="2" Body="&lt;p&gt;It's tough to tell based on your question, but I think you are talking about an inspection due to an over-G reported on a flight either by the pilot or the flight control system post-flight report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintainers will do inspections of known stress points on the aircraft to look for breaks, cracking or loosened parts and then declare it safe for flight or fix anything out of tolerance.  For a low level over-G, this could be pulling a few panels.  For higher level over-Gs it could be 8 hours worth of work&lt;/p&gt;&#xA;" OwnerUserId="14451" LastActivityDate="2016-04-17T19:14:46.663" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27018" PostTypeId="2" ParentId="25152" CreationDate="2016-04-17T19:23:34.100" Score="0" Body="&lt;p&gt;From my experience, tower controllers are always being trained to use consistent phrases to make instructions clear at their airport, but in the end you are dealing with humans trying to communicate what they want you to do and what the limits of your clearance are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To me, it is more relevant to your question that one controller is using a specific heading for you departure and the other referenced the local field downwind pattern.  For your 1st example you are expect to turn to the specific heading of 180 and then proceed on our VFR departure.  For your second example all you have to do is turn toward the downwind leg and then proceeded on your departure, giving you more leeway.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Keep in mind you are departing VFR so I wouldn't overthink it so long as you are complying with specific instructions.&lt;/p&gt;&#xA;" OwnerUserId="14451" LastActivityDate="2016-04-17T19:23:34.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27019" PostTypeId="1" AcceptedAnswerId="27032" CreationDate="2016-04-17T20:18:04.607" Score="37" ViewCount="5116" Body="&lt;p&gt;In a previous question the P&amp;amp;W J 58 engine for the SR-71 was discussed. The engine was a new and innovative design combining the characteristics of a turbojet and a ramjet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before flying with such a new design I would think they would want to test it on the ground as much as possible to ensure the safety of the pilot and the aircraft. Otherwise you're sending a guy up with things that &lt;em&gt;should&lt;/em&gt; work but so far only on paper. (I know that's what test pilots signed up for but they don't want to be reckless about it.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d3zlX.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d3zlX.jpg&quot; alt=&quot;J-58 ground test&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;J-58 ground test. &lt;sup&gt;from &lt;a href=&quot;https://en.wikipedia.org/wiki/File%3AJ58_AfterburnerT.jpeg?wprov=sfla1&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia commons&lt;/a&gt;&lt;/sup&gt;   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I know a pure ramjet won't even operate at zero airspeed. What I'm wondering is how much can be learned from ground testing on such a radical new design, or any supersonic design for that matter? Can supersonic conditions be replicated on the ground?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="13197" LastEditDate="2016-04-17T20:20:42.213" LastActivityDate="2018-02-14T09:25:55.277" Title="Can supersonic conditions be replicated on the ground?" Tags="&lt;jet-engine&gt;&lt;flight-testing&gt;&lt;engine-design&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27020" PostTypeId="1" CreationDate="2016-04-17T20:41:01.393" Score="8" ViewCount="875" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iZ50Q.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iZ50Q.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/thumb/7/77/Turbofan_operation_lbp.svg/220px-Turbofan_operation_lbp.svg.png&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;N1 and N2 are the rotational speeds of the engine sections expressed as a percentage of a nominal value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is similar to the revolutions per minute (RPM) of a piston engine, expressed in percentage instead of in the actual rate of rotation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are different because they are characteristic on two-spool engines (see the figure below). The first spool is the low pressure compressor (LP), that is N1 and the second spool is the high pressure compressor (HP), that is N2. The shafts of the engine are not connected and they operate separately.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KLHgK.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KLHgK.gif&quot; alt=&quot;Turbojet Engine&quot;&gt;&lt;/a&gt;&#xA;Image &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/Images/turbth.gif&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14539" LastEditorUserId="12220" LastEditDate="2016-04-17T20:58:55.123" LastActivityDate="2016-06-18T11:47:30.533" Title="Is there a relationship between turbojet engine rpm (N1 &amp; N2) and fuel consumption rate?" Tags="&lt;jet-engine&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27021" PostTypeId="1" CreationDate="2016-04-17T21:14:12.840" Score="1" ViewCount="59" Body="&lt;p&gt;When the time comes to make a runway change, let's say because wind has changed direction, how is this performed?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Aircraft might already be on finals, what does ATC do? Do they ask them if they want to continue with the approach or be vectored to another runway?&lt;/li&gt;&#xA;&lt;li&gt;Aircraft might not be on finals but being vectored to the finals. Same question here.&lt;/li&gt;&#xA;&lt;li&gt;Finally, there might be aircraft on the ground already taxied to the runway. Do they takeoff anyway or do they taxi to the new runway?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="878" LastActivityDate="2016-04-17T21:14:12.840" Title="How are runway changes performed when radar vectoring is available?" Tags="&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2016-04-17T21:52:17.007" ContentLicense="CC BY-SA 3.0" />
  <row Id="27022" PostTypeId="1" CreationDate="2016-04-17T21:27:28.690" Score="11" ViewCount="1541" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/kHA41.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/kHA41.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This plane was probably built around 1912. I do not know by what company built this. Does anyone know what airplane this is?&lt;/p&gt;&#xA;" OwnerUserId="14524" LastEditorUserId="595" LastEditDate="2016-04-18T19:42:45.227" LastActivityDate="2016-04-19T04:27:19.857" Title="Can anyone identify this pusher biplane?" Tags="&lt;aircraft-identification&gt;&lt;biplane&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27023" PostTypeId="2" ParentId="27020" CreationDate="2016-04-17T21:33:31.100" Score="2" Body="&lt;p&gt;Yes, these need to be roughly proportional for the engine to work, and will move towards an equilibrium if they are not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The compressor provides the air for the combustion, and injecting more fuel will only generate a little extra power, which however increases the turbine speed, increasing air intake, which will allow more fuel to be burned, again increasing available power and so on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In practice, if the air/fuel mixture is way off, &lt;a href=&quot;https://www.youtube.com/watch?v=MQWYhsYfMxE&quot; rel=&quot;nofollow&quot;&gt;compressor surges&lt;/a&gt; can happen, so in modern systems the engine computer will limit fuel flow.&lt;/p&gt;&#xA;" OwnerUserId="3333" LastActivityDate="2016-04-17T21:33:31.100" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27024" PostTypeId="2" ParentId="27003" CreationDate="2016-04-17T22:14:51.413" Score="7" Body="&lt;p&gt;Actually, the task of the diffusor was to create thrust. Sounds strange? Then read on!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At supersonic speed the spike ahead of the inlet will create a cascade of ever-steeper shocks in order to slow down and compress the air. Inside, the cross section narrows down further until the flow is decelerated to below Mach 1 in a final, straight shock. This is the point of the smallest cross section, called the throat. Falling to subsonic speed fundamentally &lt;a href=&quot;https://aviation.stackexchange.com/questions/56222/what-is-compressibility-drag/57430#57430&quot;&gt;changes the behavior of the flow&lt;/a&gt;: When before, at supersonic speed, it would slow down in a narrowing cross-sectional profile, it now needs a widening cross-sectional profile to slow down further. As it slows down, the kinetic energy of the flow is converted to pressure, so at the compressor face the flow is only Mach 0.4 fast, but has almost 40 times ambient pressure. Note that this is about the pressure ratio of modern jet engines like the F120 or the GE90 and way above the pressure ratios of 1950's-era turbo compressors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By moving the cone, the position of the throat is adjusted such that the intake works over the full flight speed range. From subsonic to Mach 3.2 the capture area increases by 112% while the throat width is narrowed to 54% of its subsonic value.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The diffusor is needed to slow down the subsonic region of the intake flow. At the same time it is filled with high-pressure air which pushes at its walls. The pressure acting on the projection area in flight direction is contributing the majority of the total thrust of the J58. The job of the engine is to suck away the air in the diffusor and to eventually accelerate it back to flight speed and above. Without the engine, the same pressure would be acting on the rear wall of the diffusor and would cause massive drag - the engine had to pump all that air away to avoid this to happen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the claim of 80% thrust made on &lt;a href=&quot;http://www.456fis.org/YF-12A_SR-71_ENGINE.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt; is not quite true, but it illustrates the point.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At Mach 3.2 cruise the inlet system itself actually provided 80&#xA;  percent of the thrust and the engine only 20 percent, making the J58&#xA;  in reality a turbo-ramjet engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A little down, it presents us with more credible numbers:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;At Mach 3, the inlet itself produces 54% of total thrust through&#xA;  pressure recovery, the engine contributing only 17% and the ejector&#xA;  system 29%. The compression ratio at cruise is 40 to 1.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Also, the reason to call it a turbo-ramjet is actually a different one, as given on &lt;a href=&quot;http://solarnavigator.net/aviation_and_space_travel/jet_engine.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;this page&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The SR-71's Pratt &amp;amp; Whitney J58 engines were rather unusual. They&#xA;  could convert in flight from being largely a turbojet to being largely&#xA;  a compressor-assisted ramjet. At high speeds (above Mach 2.4), the&#xA;  engine used variable geometry vanes to direct excess air through 6&#xA;  bypass pipes from downstream of the fourth compressor stage into the&#xA;  afterburner. 80% of the SR-71's thrust at high speed was generated in&#xA;  this way, giving much higher thrust, improving specific impulse by&#xA;  10-15%, and permitting continuous operation at Mach 3.2. The name&#xA;  coined for this configuration is turbo-ramjet.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Please note that all the diagrams which show air flowing from the diffusor directly to the afterburner don't get it quite right: Some air was needed for cooling, but also the &lt;a href=&quot;https://aviation.stackexchange.com/questions/32187/is-it-possible-to-create-a-direct-supersonic-airflow-to-a-turbofans-afterburner/32193#32193&quot;&gt;first four stages of the compressor were still involved&lt;/a&gt;, and the remainder of the turbo machinery also had to be working at Mach 3.2 to supply the compressor with torque. The J-58 took compressed air from the compressor at stage 4 and piped it directly into the flow aft of the turbine. This cooled the exhaust stream that entered the afterburner, so the starting temperature there was lower and the density higher, which increases efficiency and thrust. See the thick black tubes in the J58 picture below (&lt;a href=&quot;http://roadrunnersinternationale.com/image/j_58_transparent2.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) - those piped the compressed air to the afterburner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VFsKG.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VFsKG.gif&quot; alt=&quot;J58 engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All supersonic intakes use this principle: See below for a breakdown of thrust contributions inside the Concorde's &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593&quot; rel=&quot;nofollow noreferrer&quot;&gt;Olympus 593&lt;/a&gt; engine and nacelle:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7Vw1r.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Vw1r.jpg&quot; alt=&quot;Concorde nacelle cross section&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concorde nacelle cross section and thrust breakdown (picture &lt;a href=&quot;http://i991.photobucket.com/albums/af32/riconc1/Concorde/Thrust.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-02-25T06:04:58.977" LastActivityDate="2019-02-25T06:04:58.977" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="27025" PostTypeId="2" ParentId="27019" CreationDate="2016-04-17T22:26:58.537" Score="12" Body="&lt;p&gt;As shown &lt;a href=&quot;http://www.lockheedmartin.com/us/products/HighSpeedWindTunnel.html&quot;&gt;here&lt;/a&gt;, Lockheed Martin has a supersonic wind tunnel capable of generating wind speeds of up to mach 5. A quick Internet search revealed an extensive list of other supersonic wind tunnels, indicating that such tech is fairly widespread. In addition, as suggested by SMSvondertann, jet- and rocket powered cars such as the &lt;a href=&quot;https://en.m.wikipedia.org/wiki/ThrustSSC&quot;&gt;Thrust SSC&lt;/a&gt; have attained supersonic speeds on land. &lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-04-17T22:26:58.537" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27026" PostTypeId="2" ParentId="27019" CreationDate="2016-04-17T22:45:03.980" Score="33" Body="&lt;p&gt;It is a struggle, but it can be done. For the J58, Pratt&amp;amp;Whitney had a test facility at West Palm Beach which would simulate conditions at speed and altitude. From &lt;a href=&quot;http://www.wvi.com/~sr71webmaster/j-58~1.htm&quot; rel=&quot;noreferrer&quot;&gt;this site&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/W4bUR.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/W4bUR.jpg&quot; alt=&quot;J-58 Engine Testing in Afterburner at test cell A-1 at Pratt and Whitney’s West Palm Beach facility.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The picture actually shows test cell A-1 at Pratt and Whitney’s West&#xA;  Palm Beach facility. […]. This test cell was actually an altitude simulation&#xA;  cell used for testing purposes. (We had a additional cell used for sea&#xA;  level runs for motors which were overhauled onsite also.)  It used a&#xA;  non-afterburning J-79 as a slave motor. The exhaust of the slave was&#xA;  introduced to the inlet of the J-58 through a series of valves thereby&#xA;  simulating the speed, temperature, and density of the air at the inlet&#xA;  normally seen during flight. In this particular picture the motor is&#xA;  running at sea level as indicated by the inlet screen.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-04-17T22:45:03.980" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27027" PostTypeId="2" ParentId="26959" CreationDate="2016-04-18T01:34:46.563" Score="10" Body="&lt;p&gt;&lt;a href=&quot;http://www.boeing.com/commercial/aeromagazine/aero_03/textonly/fo01txt.html&quot;&gt;This &lt;/a&gt;paper from Boeing sheds a light on the subject: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;[A]n intentional engine throttle up or down could create a desired yawing moment followed by a desired rolling moment. Using asymmetric thrust to control roll is not precise because of the lag time associated with engine spool-up or spool-down and should be avoided unless no other means of roll control are available. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While the paper is admittedly about righting the plane from an in flight upset, and is therefore based on a disaster scenario, the message still applies to everyday flight: asymetrical thrust is not the preferred method of control, as the delay between adjusting the throttle and the actual thrust change makes it less precise for maneuvering than the main control surfaces.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-04-18T01:34:46.563" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27028" PostTypeId="1" AcceptedAnswerId="27031" CreationDate="2016-04-18T06:28:52.587" Score="13" ViewCount="7301" Body="&lt;p&gt;I noticed that most jet engines are made out of aluminum or metal components. However, carbon fiber has a melting point of 3500 degrees celcius, way above metal or aluminum. So, can I build an entire jet engine out of carbon fiber?&lt;/p&gt;&#xA;" OwnerUserId="14530" LastEditorUserId="1467" LastEditDate="2016-04-18T06:54:39.893" LastActivityDate="2016-04-18T11:56:53.440" Title="Why can't I build an entire jet engine out of carbon fiber?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;" AnswerCount="3" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27029" PostTypeId="1" CreationDate="2016-04-18T06:47:01.600" Score="3" ViewCount="273" Body="&lt;p&gt;The Harrier jump jet, while still in use in other countries, has been decomissioned in the UK, as the article below from the DailyMail mentions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hiHNh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Harrier jump jet for sale on eBay at £69,999&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the causes of a still capable aircraft to be decomissioned?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it due mainly to political reasons, like this other article suggests in the case of the Harriers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.telegraph.co.uk/news/uknews/defence/8892953/US-military-to-buy-Britains-scrapped-fleet-of-Harrier-jets.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;US military to buy Britain's scrapped fleet of Harrier jets&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The US military has agreed to buy Britain’s entire fleet of Harrier&#xA;  jump jets after they were controversially scrapped under the&#xA;  Government’s austerity measures.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hiHNh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hiHNh.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;In action: Harrier T2 XW269 on active service in Gutersloh, Germany&lt;/p&gt;&#xA;" OwnerUserId="11358" LastEditorUserId="12220" LastEditDate="2016-04-18T12:35:47.743" LastActivityDate="2016-04-18T12:35:47.743" Title="What causes a military aircraft to be decomissioned?" Tags="&lt;military&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2016-04-24T11:52:29.267" ContentLicense="CC BY-SA 3.0" />
  <row Id="27030" PostTypeId="2" ParentId="27028" CreationDate="2016-04-18T07:04:06.100" Score="11" Body="&lt;p&gt;What is relevant is not the melting point, but the temperature at which the material loses its mechanical properties (such as stiffness or elasticity).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The epoxy (the material keeping together the fibers) will usually degrade much sooner than the fibers, basically voiding the benefit of the material.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;http://www.iccm-central.org/Proceedings/ICCM17proceedings/Themes/Materials/CARBON%20-%20CARBON%20COMPOSITES/D3.6%20Kobayashi.pdf&quot;&gt;studies&lt;/a&gt; to increase the resistance to high temperatures, but I have no idea how near we are to see them applied to critical components such as the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that usually the blades of the turbine and the combustion chambers are made of alloys designed specifically to resist the high temperatures in those areas of the engines.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-04-18T07:15:36.147" LastActivityDate="2016-04-18T07:15:36.147" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27031" PostTypeId="2" ParentId="27028" CreationDate="2016-04-18T07:26:04.893" Score="29" Body="&lt;p&gt;No, you can not. Carbon fibre composites always contain a matrix component which serves different functionalities, but (in a micro nutshell) bonds and keeps the fibres in place. What you get is a very complex material with lots of lightweight potential, but also very different property profiles compared to metals.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most matrix materials (thermoset, thermoplastics) will not work up to engine (combustion chamber) temperatures and either degrade/burn or melt/vaporize/burn long before reaching even a meagre few hundred Kelvin (say, 500K). In fact, carbon fibres will not work as well in an oxygenated high-temperature environment, and degrade/burn up as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One composite material that works and is used already in engines are ceramic matrix composites, like (amongst others) e.g. C/C-SiC structures, but those are very special animals (and even there the carbon fibre parts are susceptible to burn). Especially in terms of mechanical properties, these cannot compete with superalloys.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But also for many other, ambient temperature parts, metals are much better suited. Think of example of a ball bearing - doing that completely in composite will not work really well (if at all).&lt;/p&gt;&#xA;" OwnerUserId="95" LastEditorUserId="95" LastEditDate="2016-04-18T08:23:47.863" LastActivityDate="2016-04-18T08:23:47.863" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27032" PostTypeId="2" ParentId="27019" CreationDate="2016-04-18T07:31:43.900" Score="43" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, supersonic conditions can indeed be replicated on the ground for purposes of airframe and engine testing.&lt;/p&gt;&#xA;&lt;h2&gt;Arnold Engineering Development Complex (AEDC)&lt;/h2&gt;&#xA;&lt;p&gt;The U.S. Air Force and NASA both operate supersonic wind tunnels, as do Lockheed, P&amp;amp;W, and others. The most advanced of these facilities are probably those at &lt;a href=&quot;https://en.wikipedia.org/wiki/Arnold_Engineering_Development_Complex&quot; rel=&quot;noreferrer&quot;&gt;Arnold Engineering Development Complex&lt;/a&gt; on Arnold Air Force Base. I won't mention any specific numbers from memory because they've likely changed since I worked there and I can't remember exactly which ones were classified/FOUO/otherwise-not-public, but let's just say they're pretty good.&lt;/p&gt;&#xA;&lt;p&gt;AEDC has test cells designed both for testing jet engines as well as for testing scale models of airframes (or full scale airframes if it's a small enough airframe, such as a missile.) Additionally, it has facilities for testing upper-stage rocket motors. Lower-stage rocket motors don't need the facilities at Arnold, as those are designed to operate in the atmosphere and can just be lit up out in a desert somewhere.&lt;/p&gt;&#xA;&lt;p&gt;According to Wikipedia (which I believe is sourced from publically-available information,) &lt;a href=&quot;https://en.wikipedia.org/wiki/Hypervelocity_Wind_Tunnel_9&quot; rel=&quot;noreferrer&quot;&gt;Hypervelocity Wind Tunnel 9&lt;/a&gt; can generate air flow of Mach 14 with simulated altitudes from sea level to 173,000 ft.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RBMz5.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RBMz5.jpg&quot; alt=&quot;AEDC Tunnel 9 with Test Article&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;strong&gt;AEDC Tunnel 9 (with test article)&lt;/strong&gt;  Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Hypervelocity_Wind_Tunnel_9#/media/File:THAAD_testing_in_Tunnel_9.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;In case that's not enough, &lt;a href=&quot;https://en.wikipedia.org/wiki/AEDC_Range_G&quot; rel=&quot;noreferrer&quot;&gt;G Range&lt;/a&gt; can fire projectiles at roughly the speed of low Earth orbit. However, this one is kind of stretching the definition of &amp;quot;supersonic,&amp;quot; since it's typically pumped down to such negligible air pressure that Mach number isn't really defined before a shot at that kind of velocity. Still, as the wiki article indicates, it's capable of shots at up to 1.7 atmospheres, so it definitely counts as legitimately supersonic on those shots.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8yE2S.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8yE2S.jpg&quot; alt=&quot;AEDC G Range&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;strong&gt;AEDC Range G&lt;/strong&gt;  Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/AEDC_Range_G#/media/File:AEDC_Range-G_Launcher_facility.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;h2&gt;Holloman Air Force Base&lt;/h2&gt;&#xA;&lt;p&gt;In addition to wind tunnels and other facilities at AEDC, the U.S. Air Force also occasionally uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Rocket_sled&quot; rel=&quot;noreferrer&quot;&gt;rocket sleds&lt;/a&gt;, such as the one at &lt;a href=&quot;https://en.wikipedia.org/wiki/Holloman_High_Speed_Test_Track&quot; rel=&quot;noreferrer&quot;&gt;Holloman Air Force Base&lt;/a&gt;, which currently holds &lt;a href=&quot;https://en.wikipedia.org/wiki/Land_speed_record_for_rail_vehicles#Rocket_sleds&quot; rel=&quot;noreferrer&quot;&gt;the speed record for any type of non-air/space vehicle&lt;/a&gt; at 6,416 mph / 10,326 km/h (Mach 8.5.)&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GTJ4n.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GTJ4n.jpg&quot; alt=&quot;Holloman High Speed Test Track&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;strong&gt;Holloman High Speed Test Track&lt;/strong&gt; Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Holloman_High_Speed_Test_Track#/media/File:HHSTT_View_from_South_to_North.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o6yB0.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o6yB0.jpg&quot; alt=&quot;Land Speed Record Rocket Sled at Holloman&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;strong&gt;Land Speed Record Rocket Sled at Holloman&lt;/strong&gt; Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Land_speed_record_for_rail_vehicles#/media/File:8.5_Mach_rocket_sled_030430.jpg&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2SrIo.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2SrIo.jpg&quot; alt=&quot;Holloman &amp;quot;Speed Limit&amp;quot;&quot; /&gt;&lt;/a&gt;&#xA;&lt;strong&gt;The &amp;quot;Speed Limit&amp;quot; at Holloman Air Force Base&lt;/strong&gt;&lt;br /&gt;&#xA;Source: &lt;a href=&quot;http://www.crviewer.com/targets/120516/120516.htm&quot; rel=&quot;noreferrer&quot;&gt;some guy's website&lt;/a&gt;, which got them from publically-released images from Holloman AFB&lt;/p&gt;&#xA;" OwnerUserId="755" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-02-14T09:25:55.277" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27034" PostTypeId="2" ParentId="25152" CreationDate="2016-04-18T10:56:29.297" Score="4" Body="&lt;p&gt;It depends on local custom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some airports have multiple runways, so controllers will use compass points instead of pattern legs, and this habit will carry over when they are assigned to a single-runway airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other airports have noise abatement procedures which have specific names. Below are the departures for San Carlos airport, and pilots are expected to use a named departure, such as &quot;Belmon Slough Departure&quot; instead of &quot;right-crosswind departure,&quot; and tower will readback the named departure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/K8xDt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/K8xDt.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-18T10:56:29.297" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27035" PostTypeId="1" CreationDate="2016-04-18T11:12:40.577" Score="11" ViewCount="453" Body="&lt;p&gt;I recently flew for the first time on a &lt;a href=&quot;https://www.flightradar24.com/data/aircraft/a7-bcy&quot;&gt;Boeing 787-8 Dreamliner, registered A7-BCY&lt;/a&gt;. This aircraft had the universal symbol for wifi externally displayed beside the entrance door, and as wifi on an aircraft was another first for me I was keen to try it out. Which I did, without much fanfare.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wifi used to provide internet access was named along the lines of &quot;OneAir&quot;, which is consistent with the name of that airline's connectivity/On-board entertainment services.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What intrigued me was that there was a second wifi network available (albeit secured from public access) which was named with the aircraft's registration &quot;A7-BCY&quot; in the SSID of the network. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of this network? What data would you be able to access/see if you were to connect to it using a laptop (for example)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note: I know there have been some questions here and on computer security regarding the vulnerability of modern airliners to hackers - I'm less interested in &quot;doomsday scenarios&quot; with this technology, and more interested on what legitimate uses there are of this network)&lt;/p&gt;&#xA;" OwnerUserId="100" LastEditorUserId="13197" LastEditDate="2016-04-20T15:11:36.273" LastActivityDate="2016-09-27T22:56:26.947" Title="What is the purpose of the second wifi network on board (some?) B787 aircraft?" Tags="&lt;airlines&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="27036" PostTypeId="2" ParentId="27028" CreationDate="2016-04-18T11:56:53.440" Score="8" Body="&lt;p&gt;When I was beginning my university studies in engineering 15 years ago our professor told us that they actually think of building jet engines of that material!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Carbon-based materials seem to be the perfect material for jet engines in nearly all points (heat resistance, mechanical strength at high temperatures, weight, ...) with one important exception:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These materials burn when they get in contact with hot air!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The professor told us that a lot of effort and money is spent in search of a coat or varnish that would protect carbon-based parts from the hot air. He told us that jet engines would be built of that material if such a coat is found.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He also told us that up to then no suitable coat was found - obviously this has not changed in the last 15 years.&lt;/p&gt;&#xA;" OwnerUserId="14550" LastActivityDate="2016-04-18T11:56:53.440" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27037" PostTypeId="2" ParentId="12656" CreationDate="2016-04-18T12:43:00.167" Score="0" Body="&lt;p&gt;The power required to maintain altitude at forward flight is lower than the power required to hover. As horizontal velocity ($V_x$) increases, the induced velocity ($V_i$) at the disc decreases, and induced power ($P_i$) decreases roughly equal to $\frac{1}{V_i}$. However, as $V_x$ increases, parasitic power ($P_p$) increases proportional to $V^3$. Profile power ($P_0$ - the power needed to maintain rotor speed) remains roughly constant. If you chart all of these together with Required Power on the y-axis and forward velocity on the x-axis, you end up with something that looks like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zEfMF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zEfMF.jpg&quot; alt=&quot;Power vs forward speed&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means is that there's an optimum forward speed at which your power is minimized. This is important, because the max rate of climb (and lifting power) is determined by your available power $$P_{av} = P_{tot} - P_i - P_p - P_0$$. If you minimize the power needed to keep the aircraft flying, you have more net power for lifting other things (and for heavy helicopters, they may not be able to take off vertically at all). For this reason, the max rate of climb will always be at some forward speed, and by definition, the max lifting capacity will also be at some forward velocity. A practical demonstration of this principle is that large cargo lifters like the sky crane and the chinook always take off with some forward velocity component. This is why.&lt;/p&gt;&#xA;" OwnerUserId="14552" LastEditorUserId="4197" LastEditDate="2016-04-19T15:08:20.313" LastActivityDate="2016-04-19T15:08:20.313" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27038" PostTypeId="2" ParentId="26880" CreationDate="2016-04-18T13:09:26.487" Score="6" Body="&lt;p&gt;Your question was inadvertently answered by &lt;a href=&quot;https://aviation.stackexchange.com/users/1961/peter-k%c3%a4mpf&quot;&gt;Peter Kämpf&lt;/a&gt; when he provided &lt;a href=&quot;https://aviation.stackexchange.com/a/27026/5517&quot;&gt;this answer&lt;/a&gt; to another question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One jet engine was placed in front of another in a test facility to test the high speed, high altitude performance of the trailing &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J58&quot; rel=&quot;nofollow noreferrer&quot;&gt;PW J58&lt;/a&gt; when it was chosen to power the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow noreferrer&quot;&gt;SR-71&lt;/a&gt;. Test details located &lt;a href=&quot;http://www.wvi.com/~sr71webmaster/j-58~1.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-18T14:13:02.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27040" PostTypeId="1" CreationDate="2016-04-18T13:50:50.923" Score="3" ViewCount="1055" Body="&lt;p&gt;In the mid-air collision over Uberlingen, why couldn't the DHL611 crew hear the instructions given by the controller to Bashkirian 2937 crew if both aircraft were on the same frequency?&lt;/p&gt;&#xA;" OwnerUserId="13675" LastEditorUserId="22726" LastEditDate="2019-02-22T04:11:37.703" LastActivityDate="2019-02-22T04:11:37.703" Title="Why couldn't the DHL611 crew hear the ATC transmissions for the Bashkirian 2937 crew?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;accidents&gt;&lt;mid-air-collision&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27041" PostTypeId="1" AcceptedAnswerId="27081" CreationDate="2016-04-18T14:04:51.133" Score="3" ViewCount="698" Body="&lt;p&gt;I am working on an assignment and I need to calculate the center of pressure of an airfoil, through a numerical method (the panel method). I am getting a weird result because it gives its position on a point outside the chord for a determined angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I asked my professor he said that under an angle of attack near the angle of attack that makes Cl=0, it may come out that way, because the center of pressure is calculated through an expression that involves a quotient with the Cl=0 on its denominator.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am confused because I don't know if it is just that the method fails in that case, or if it has some physical explanation. &lt;/p&gt;&#xA;" OwnerUserId="14554" LastEditorUserId="19" LastEditDate="2016-08-09T11:27:56.917" LastActivityDate="2016-08-09T11:27:56.917" Title="Why is the numerically determined location of the center of pressure inaccurate near Cl = 0?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;airfoil&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27042" PostTypeId="2" ParentId="27040" CreationDate="2016-04-18T16:19:25.430" Score="11" Body="&lt;p&gt;It wouldn't matter if they had.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DHL611 crew had been trained to obey TCAS orders over ATC. This was fairly common, but not universal practice at the time. Their training was unambiguous, and stated that TCAS should be followed over ATC instructions. They had been trained that both aircraft would follow TCAS and avoid the collision, and had no reason to believe that wasn't the case: they didn't even necessarily know that BTC2937 was the aircraft causing their TCAS alert&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The crew of BTC2937 hadn't been trained to follow these priorities, or became confused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the Wikipedia page about the incident:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The TCAS Pilot's Guide was ambiguous as to whether or not TCAS advisories should take precedence over ATC instructions.[BFU 14] This ambiguity was replicated in the Tu-154 Flight Operations Manual, which contained contradictory sections. On the one hand, chapter 8.18.3.4 emphasized the role of the ATC and describes the TCAS as an &quot;additional aid&quot;,[BFU 15] whilst chapter 8.18.3.2 forbids manoeuvers contrary to the TCAS&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since that accident, it was made official procedure for all flights to follow TCAS, ignoring ATC when a TCAS RA is in effect.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-04-18T16:19:25.430" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27043" PostTypeId="1" AcceptedAnswerId="27046" CreationDate="2016-04-18T18:14:08.013" Score="6" ViewCount="828" Body="&lt;p&gt;Is there any sensor incorporated on the Passenger Service Unit that tells the masks to deploy when a cabin decompression occurs? &lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="12220" LastEditDate="2016-04-18T18:38:42.727" LastActivityDate="2016-04-18T18:48:40.823" Title="How do the oxygen masks deploy after a cabin decompression?" Tags="&lt;oxygen&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27044" PostTypeId="1" CreationDate="2016-04-18T18:15:55.287" Score="-1" ViewCount="3072" Body="&lt;p&gt;An aircraft heading west at an airspeed of 100 km/h has a crosswind blowing from the south at 100 km/h. What will be the aircraft's speed relative to the ground?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The correct answer is 141km/h. Can anyone explain and give the formula?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is it? I know it but I need the formula with which it is calculated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I found &lt;a href=&quot;http://www.physicsclassroom.com/class/vectors/Lesson-1/Relative-Velocity-and-Riverboat-Problems&quot; rel=&quot;nofollow&quot;&gt;Pythagorean theorem&lt;/a&gt; for this (but since the directions of heading and wind are not the same result is not same here, so it must be another formula).&lt;/p&gt;&#xA;" OwnerUserId="14557" LastEditorUserId="1696" LastEditDate="2016-07-06T21:55:28.277" LastActivityDate="2016-07-06T21:55:28.277" Title="How does a crosswind affect an aircraft's speed relative to the ground?" Tags="&lt;flight-planning&gt;" AnswerCount="1" CommentCount="5" ClosedDate="2016-04-18T20:07:59.870" ContentLicense="CC BY-SA 3.0" />
  <row Id="27045" PostTypeId="2" ParentId="27044" CreationDate="2016-04-18T18:20:44.640" Score="3" Body="&lt;p&gt;&lt;strong&gt;Simple Answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Pythagorean Theorem does give the correct answer as the square root to the whole number of $100^2 + 100^2$ is indeed 141. This works only if the wind is blowing at right angles to your compass direction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;More trigonometric function-based method&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to get to 141 is to divide 100 by $\sin 45^{\circ}$ or $\cos 45^{\circ}$ because the triangle has two equal legs. (Your airspeed and wind speed are equal at 100 knots.) Therefore, the angles opposite them must be equal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, since it is a right triangle and the sum of angles in a triangle is 180, the other two angles’ sum must be 90. Since the angles are equal, $\frac{90}{2} = 45$. The sine of an angle is the ratio of the side opposite the angle to the hypotenuse (your groundspeed). Doing a little rearranging of the terms, it comes out that the groundspeed is 100 divided by the sine of 45.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\begin{align}&#xA;\sin 45^{\circ} &amp;amp; = \frac{\mathrm{crosswind}}{\mathrm{groundspeed}} \\&#xA;\\&#xA;\mathrm{groundspeed} \cdot \sin 45^{\circ} &amp;amp;= \mathrm{crosswind} \\&#xA;\\&#xA;\mathrm{groundspeed} &amp;amp;= \frac{\mathrm{crosswind}}{\sin 45^{\circ}}&#xA;\end{align}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, for the other angles created by the wind-heading combination, you would have to get the different components together and use either the &lt;a href=&quot;https://en.wikipedia.org/wiki/Law_of_sines&quot; rel=&quot;nofollow&quot;&gt;Law of Sines&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Law_of_cosines&quot; rel=&quot;nofollow&quot;&gt;Cosines&lt;/a&gt;, depending on what components you have.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="2143" LastEditDate="2016-04-18T20:38:05.773" LastActivityDate="2016-04-18T20:38:05.773" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27046" PostTypeId="2" ParentId="27043" CreationDate="2016-04-18T18:48:40.823" Score="3" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.airliners.net/aviation-forums/tech_ops/read.main/291546/&quot; rel=&quot;nofollow&quot;&gt;this &lt;/a&gt;Airliners.net forum post, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The masks are deployed automatically (typically when cabin altitude exceeds 14,000 feet), or can be deployed manually from the flight deck. In addition, if a passenger service unit oxygen door should fail to open, cabin crew can open the PSU door (either inserting a flat object or a special tool depending on the aircraft type) manually. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So basically, the masks are deployed automatically based on sensors, with manual deployment as a primary failsafe and physical access as a secondary failsafe.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastActivityDate="2016-04-18T18:48:40.823" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27048" PostTypeId="1" AcceptedAnswerId="27053" CreationDate="2016-04-18T19:18:00.993" Score="9" ViewCount="1764" Body="&lt;p&gt;Just to clarify: I am explicitly &lt;em&gt;not&lt;/em&gt; referring to the &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Bell_X-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Bell X-1&lt;/a&gt;, or any other early experimental supersonic aircraft that were rocket-powered. I'm curious as to the first supersonic aircraft powered by an &lt;em&gt;air-breathing&lt;/em&gt; jet engine, as well as (if possible) the technological innovations needed to transition from rocket-powered to air-breathing supersonic flight.&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="15311" LastEditDate="2018-06-10T19:02:07.017" LastActivityDate="2021-03-01T15:14:05.737" Title="What was the first jet-powered supersonic aircraft?" Tags="&lt;aircraft-design&gt;&lt;aviation-history&gt;&lt;jet&gt;&lt;supersonic&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="27049" PostTypeId="1" AcceptedAnswerId="27051" CreationDate="2016-04-18T19:21:39.123" Score="12" ViewCount="2832" Body="&lt;p&gt;I found a little &quot;door&quot; on the upper deck of this A380:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EIUbn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EIUbn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Lufthansa/Airbus-A380-841/2570598/L/&amp;amp;sid=760e921a06af5d6640f3f59d59b02741&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the purpose of that door, hatch, whatever?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastActivityDate="2019-10-10T17:37:10.733" Title="What is this little door on the upper deck of the A380?" Tags="&lt;aircraft-design&gt;&lt;airbus-a380&gt;" AnswerCount="3" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27050" PostTypeId="2" ParentId="27049" CreationDate="2016-04-18T19:28:50.133" Score="21" Body="&lt;p&gt;It's for the emergency slide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see it deployed here:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/y0KVk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/y0KVk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:  Airliners.Net&lt;/p&gt;&#xA;" OwnerUserId="595" LastActivityDate="2016-04-18T19:28:50.133" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27051" PostTypeId="2" ParentId="27049" CreationDate="2016-04-18T19:38:24.710" Score="12" Body="&lt;p&gt;Looking at Airbus's &lt;a href=&quot;http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-Dec2014.pdf&quot; rel=&quot;noreferrer&quot;&gt;diagram gallery&lt;/a&gt; on the A380, this image suggests that the panel is to store and deploy the emergency evacuation slides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9T09J.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9T09J.jpg&quot; alt=&quot;Slide diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is also supported by another picture from the same document, in which similar doors are seen under each second row entrance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O5k7m.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O5k7m.jpg&quot; alt=&quot;Door diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="1696" LastEditDate="2019-10-10T17:37:10.733" LastActivityDate="2019-10-10T17:37:10.733" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="27052" PostTypeId="1" CreationDate="2016-04-18T19:58:43.640" Score="1" ViewCount="106" Body="&lt;p&gt;I have seen many videos, and I noticed that only the inner engine reverses were opened. Why not on the 4 engines?&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="14354" LastEditDate="2016-04-18T20:10:25.450" LastActivityDate="2016-04-18T20:10:25.450" Title="Why does Airbus A380 have only reversers on inner engines?" Tags="&lt;airbus-a380&gt;" AnswerCount="0" CommentCount="1" ClosedDate="2016-04-18T20:15:53.360" ContentLicense="CC BY-SA 3.0" />
  <row Id="27053" PostTypeId="2" ParentId="27048" CreationDate="2016-04-18T20:05:39.327" Score="14" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Hans_Guido_Mutke&quot;&gt;One ME-262 Pilot&lt;/a&gt; claims to have exceeded Mach 1 in a dive, but the conditions are disputed due to compressibility and later tests that find the aircraft uncontrollable above Mach .84. The first U.S. fighter plane to exceed Mach 1 in level flight is the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_F-100_Super_Sabre&quot;&gt;F-100 Super Sabre&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For research on how the sound barrier was broken as it results to aircraft design is to read &lt;a href=&quot;https://en.wikipedia.org/wiki/Sound_barrier&quot;&gt;Wikipedia: Sound Barrier&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia also has a good read on &lt;a href=&quot;https://en.wikipedia.org/wiki/Supersonic_aircraft&quot;&gt;Supersonic Aircraft&lt;/a&gt; that lists aircraft by manufacture date.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for technological innovations, I would suggest reading about the &lt;a href=&quot;https://en.wikipedia.org/wiki/Turbofan&quot;&gt;turbofan engine&lt;/a&gt;, specifically &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/inlet.html&quot;&gt;inlet design&lt;/a&gt; since the air must be slowed sub-sonic before entering the compressor stages. &lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-04-18T20:05:39.327" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27054" PostTypeId="1" CreationDate="2016-04-18T20:54:02.180" Score="0" ViewCount="105" Body="&lt;p&gt;A bird, or indeed any object, entering a jet engine is a very undesirable situation and may cause engine failure. There are also fears we're not far away from seeing the first incident of a drone entering a jet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do we not see grilles or cages on the front of the jet engines to prevent this happening?&lt;/p&gt;&#xA;" OwnerUserId="7576" LastActivityDate="2016-04-18T20:54:02.180" Title="Could jet engines have a grille to prevent bird or drone entry?" Tags="&lt;jet-engine&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-04-18T21:01:09.887" ContentLicense="CC BY-SA 3.0" />
  <row Id="27055" PostTypeId="2" ParentId="27019" CreationDate="2016-04-18T20:55:20.840" Score="8" Body="&lt;p&gt;Not quite on the ground, but some organisations go to quite extreme lengths to simulate supersonic conditions. Take NASA and their supersonic parachute intended for Martian atmospheric entry, also known as the Low-Density Supersonic Decelerator. They recently tested this on a quite startling rig:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;-The parachute was dropped from a helicopter&lt;br&gt;&#xA;-A 1km steel rope attached the chute to a winch via a pulley&lt;br&gt;&#xA;-The winch keeps the rope under tension...&lt;br&gt;&#xA;-...and is attached to the the star of the show - a 4-motor rocket sled, designed to accelerate the parachute to extreme speed before it hits the ground.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This rig is worth mentioning not least because the description conjures up an image of a pile of empty ACME boxes!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nasa.gov/mission_pages/tdm/ldsd/index.html#.Uuu6_PldXXs&quot;&gt;See here for further information&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14559" LastEditorUserId="1467" LastEditDate="2016-04-19T10:22:42.737" LastActivityDate="2016-04-19T10:22:42.737" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27057" PostTypeId="1" CreationDate="2016-04-19T02:20:46.833" Score="1" ViewCount="100" Body="&lt;p&gt;Nowadays we have space crafts that go as far as to the Mars and they are controlled by people sitting in the earth (by some remote control method).Why are aeroplanes not controlled in this way?Are pilots absolutely necessary?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for any help!!&lt;/p&gt;&#xA;" OwnerUserId="14563" LastActivityDate="2016-04-19T02:20:46.833" Title="Why aren't aeroplanes controlled from a control center (without a pilot inside)?" Tags="&lt;flight-controls&gt;" AnswerCount="0" CommentCount="6" FavoriteCount="1" ClosedDate="2016-04-19T08:22:04.760" ContentLicense="CC BY-SA 3.0" />
  <row Id="27058" PostTypeId="2" ParentId="25774" CreationDate="2016-04-19T02:37:49.717" Score="5" Body="&lt;p&gt;In simple terms, mixing the exhaust flow (with any bypass ratio) is good for all the reasons except for construction and weight. It is aerodynamically more efficient; it reduces noise (exhaust noise makes most of the jet noise); it cools combustion chamber (and other downwind parts) more efficiently, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, making the mixing chamber on a high bypass / big engine would require enormous outer nacelle to cover the whole engine (and extend somewhat beyond), and the weight penalty and complexity/cost negates all the benefits.&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-04-19T02:37:49.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27059" PostTypeId="2" ParentId="27022" CreationDate="2016-04-19T03:51:23.123" Score="9" Body="&lt;p&gt;It looks like a Farman Aviation Works design but many builders copied the Farman designs. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most Farman aircraft had straight boxed struts but some had staggered wings and slanted struts:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maurice Farman biplane&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EO080.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EO080.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://flyingmachines.ru/Site2/Crafts/Craft28602.htm#tabs-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://flyingmachines.ru/Site2/Crafts/Craft28602.htm#tabs-1&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AR3X4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AR3X4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source:  &lt;a href=&quot;http://www.ebay.com/itm/FARMAN-3-SEAT-BIPLANE-At-the-French-Military-Trials-Rheims-France-1911-RP-/371424887006&quot; rel=&quot;nofollow noreferrer&quot;&gt;ebay auction&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also similar to the MF.9&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Roodo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Roodo.jpg&quot; alt=&quot;http://flyingmachines.ru/Site2/Crafts/Craft28795.htm&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:&lt;a href=&quot;http://flyingmachines.ru/Site2/Crafts/Craft28795.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://flyingmachines.ru/Site2/Crafts/Craft28795.htm&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-19T04:27:19.857" LastActivityDate="2016-04-19T04:27:19.857" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27060" PostTypeId="1" AcceptedAnswerId="27061" CreationDate="2016-04-19T05:24:01.293" Score="8" ViewCount="1846" Body="&lt;p&gt;More precisely, in the case when a straight-in approach is present, what is the maximum angle between the final approach course and the runway heading for a straight-in minimum apply? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had thought it is 15° for GPS IAP and 30° for others. However, when I looked at &lt;a href=&quot;http://flightaware.com/resources/airport/MRY/IAP/RNAV+(GPS)+Y+RWY+28L/pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;RNAV (GPS) RWY 28L @ KMRY&lt;/a&gt;, the angle is |279.4° - 261°| = 18.4° &gt; 15°. Is there any other rule that applies, or is this simply an exception?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that on IAP runway diagram (bottom-left), there is usually an arrow with a distance from FAF to MAP and course direction, and they are omitted here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NvYAq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NvYAq.jpg&quot; alt=&quot;RNAV (GPS) RWY 28L @ KMRY&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="62" LastEditDate="2016-04-20T21:16:29.000" LastActivityDate="2016-04-20T21:16:29.000" Title="What runway alignment should I expect from a straight-in approach?" Tags="&lt;faa-regulations&gt;&lt;instrument-flight-rules&gt;&lt;iaps&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27061" PostTypeId="2" ParentId="27060" CreationDate="2016-04-19T08:14:00.270" Score="8" Body="&lt;p&gt;This is an interesting question because it turns out that RNAV approach criteria aren't defined in the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FAA_Order_8260.3C.pdf&quot;&gt;TERPS&lt;/a&gt; as you would expect. Instead, there's a separate FAA order &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FAA_Order_8260.58A.pdf&quot;&gt;8260.58&lt;/a&gt; for RNAV approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The TERPS does indeed give 30° as the maximum offset for most approaches (e.g. section 4-2-4) and 15° for VOR/DME RNAV approaches (section 13-3-4), but VOR/DME RNAV approaches are still based on ground stations (section 13-1):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VOR/DME RNAV systems use signals based solely upon a VOR/DME, VORTAC,&#xA;  or TACAN reference facility. These systems use radials and distances&#xA;  from a reference facility to compute position and flight track&#xA;  information&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;On the other hand, the criteria for 'true' RNAV approaches not based on ground stations are defined in 8260.58 and they allow for offsets up to 30°  for approaches without vertical guidance (section 3-2-2):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. Offset. When the final course must be offset, it may be offset up&#xA;  to 30 degrees (published separately from vertically guided) when the&#xA;  following conditions are met:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Offset ≤ 5 degrees. Align the course through LTP.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Offset &gt; 5 degrees and 10 ≤ degrees. The course must&#xA;  cross the runway centerline extended at least 1500 feet prior to LTP&#xA;  (5200 feet maximum).  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Offset &gt; 10 degrees and ≤ 20 degrees. The&#xA;  course must cross the runway centerline extended at least 3000 feet&#xA;  prior to LTP (5200 feet maximum). For offsets &gt; 15 degrees, CAT C/D&#xA;  minimum published visibility 1 SM, minimum HAT of 300 feet.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(4) Offset 20 to 30 degrees (CAT A/B only). The course must cross the runway centerline extended at least 4500 feet prior to the LTP (5200 feet&#xA;  maximum).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the approach you showed doesn't have vertical guidance, it would fall under this section and therefore the offset of 16.76° marked on the plate is normal.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-04-20T21:03:47.450" LastActivityDate="2016-04-20T21:03:47.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27063" PostTypeId="2" ParentId="26900" CreationDate="2016-04-19T18:35:39.997" Score="11" Body="&lt;p&gt;Yes there are. Although they are not for commercial aviation. One example are solar powered engines:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Vfb5k.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Vfb5k.jpg&quot; alt=&quot;Solar Impulse&quot;&gt;&lt;/a&gt;&#xA;Source &lt;a href=&quot;https://en.wikipedia.org/wiki/Solar_Impulse&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, there are other means of storing energy - rubber bands, but this one is just for model aitplanes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/V9WLP.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/V9WLP.jpg&quot; alt=&quot;Rubber band engine.&quot;&gt;&lt;/a&gt;&#xA;Source: Pinterest&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But in either case, you need store energy somewhere, and best way is to use oil-based fuels.&lt;/p&gt;&#xA;" OwnerUserId="9146" LastEditorUserId="9146" LastEditDate="2020-05-04T20:13:33.973" LastActivityDate="2020-05-04T20:13:33.973" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="27064" PostTypeId="1" CreationDate="2016-04-20T01:24:51.627" Score="16" ViewCount="3498" Body="&lt;p&gt;It's been over 90 days since I've been flying, but I have a biennial flight review coming up pretty soon and would like to prep for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The regulations regarding this seem to be extremely vague, but is it legal for me to fly around, do my landings, log PIC time, and such with another licensed, current pilot in the plane with me?&lt;/p&gt;&#xA;" OwnerUserId="700" LastEditorUserId="2" LastEditDate="2016-04-20T05:14:35.733" LastActivityDate="2018-11-21T05:35:45.060" Title="Can I bring a person with me while getting landing current if they're a licensed, current pilot?" Tags="&lt;faa-regulations&gt;&lt;currency&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27065" PostTypeId="2" ParentId="27064" CreationDate="2016-04-20T01:47:55.953" Score="2" Body="&lt;p&gt;I don't think it's that ambiguous. The kicker in your requirementsis the &quot;log PIC time&quot; part...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://flightphysical.com/part61/currency/a.htm&quot; rel=&quot;nofollow&quot;&gt;CFR 61.57&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) General experience.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Except as provided in paragraph (e) of this section, &lt;strong&gt;no person may act as a pilot in command of an aircraft carrying passengers&lt;/strong&gt; or of an aircraft certificated for more than one pilot flight crewmember unless that person has made at least three takeoffs and three landings within the preceding 90 days, and—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) &lt;strong&gt;The person acted as the sole manipulator of the flight controls&lt;/strong&gt;;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And this section:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) For the purpose of meeting the requirements of paragraph (a)(1) of this section, a person may act as a pilot in command of an aircraft under day VFR or day IFR, &lt;strong&gt;provided no persons or property are carried on board the aircraft&lt;/strong&gt;, other than those necessary for the conduct of the flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So I interpret that as no passengers. If the other pilot is a CFI and giving instruction, then that would count but if they are just going for a ride, no its not &quot;legal&quot;. The take offs and landings have to be done either solo, not as PIC, or under instruction. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other person may be a pilot, but unless they are performing pilot duties they are a passenger like any non pilot rated passenger. By the way,  the PIC does not have to sit on the left, you can still occupy the left seat as long as your pilot friend accepts PIC responsibilities as you complete your currency then you can resume being PIC.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-20T02:06:30.970" LastActivityDate="2016-04-20T02:06:30.970" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27067" PostTypeId="2" ParentId="27064" CreationDate="2016-04-20T01:59:25.293" Score="16" Body="&lt;p&gt;As long as  you are not the legal pilot in command you can do what you want.  This means the other pilot has to be willing to act as the legal pilot in command on this flight.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=754abc363b0a3df897df6f956dde81f9&amp;amp;mc=true&amp;amp;node=se14.2.61_157&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;61.57&lt;/a&gt;(a) General experience.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Except as provided in paragraph (e) of this section, no person may&#xA;  act as a &lt;strong&gt;pilot in command&lt;/strong&gt; of an aircraft &lt;strong&gt;carrying passengers&lt;/strong&gt; or of an&#xA;  aircraft certificated for more than one pilot flight crewmember unless&#xA;  that person has made at least three takeoffs and three landings within&#xA;  the preceding 90 days, and—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) The person acted as the sole manipulator of the flight controls;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The regulation is clearly required of the legal pilot in command.  If your current passenger is willing to act and take responsibility for your flying as the legal pilot in command then it is allowable.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, the other pilot is taking all the responsibility and gets none of the credit as they, under an airplane certificated for single pilot operations, cannot log any PIC time while you are getting current.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From &lt;a href=&quot;https://www.faa.gov/about/office_org/field_offices/fsdo/sdl/local_more/avsafety_program/media/LOGGING%20PILOT-IN-COMMAND%20TIME.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;LOGGING PILOT IN COMMAND TIME (FAA)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;However, two pilots may not simultaneously log PIC when one pilot is&#xA;  sole manipulator of the controls and the other is acting as&#xA;  pilot-in-command if the regulations governing the flight do not&#xA;  require more than one pilot.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;If the other pilot is a CFI and it is a training flight then no one has to be landing current as there are no passengers.  See the &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2006/kortokrax%20-%20(2006)%20legal%20interpretation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kortokrax interpretation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Relevant excerpt:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;We agree that, for purposes of section 61.57(b), an authorized&#xA;  instructor providing instruction in an aircraft is not considered a&#xA;  passenger with respect to the person receiving instruction, even where&#xA;  the person receiving the instruction is acting as PIC. (The instructor&#xA;  must be current, qualified to instruct, and hold a category, class and&#xA;  type rating in the aircraft, if a class and type rating is required.)&#xA;  The instructor is not a passenger because he is present specifically&#xA;  to train the person receiving instruction. Neither is the person&#xA;  receiving instruction a passenger with respect to the instructor. This&#xA;  training may take place, even though neither pilot has met the&#xA;  61.57(b) requirements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="132" LastEditDate="2018-11-20T15:52:13.113" LastActivityDate="2018-11-20T15:52:13.113" CommentCount="14" ContentLicense="CC BY-SA 4.0" />
  <row Id="27068" PostTypeId="1" AcceptedAnswerId="27070" CreationDate="2016-04-20T05:48:54.077" Score="46" ViewCount="9530" Body="&lt;p&gt;I recently went to &lt;a href=&quot;https://en.wikipedia.org/wiki/Sinsheim_Auto_%26_Technik_Museum&quot; rel=&quot;nofollow noreferrer&quot;&gt;the museum in Sinsheim&lt;/a&gt;, Germany, where a &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-144&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev Tu-144&lt;/a&gt; is on display. I noticed that the landing gear of this plane is actually way wider than the space it has available when retracted. How can this work? Does the gear fold before retracting?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sadly, I wasn't able to find any video footage of the TU-144 retracting its gear. Please take a look at the picture I took to understand what I mean:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uKI4Y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uKI4Y.jpg&quot; alt=&quot;Enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14457" LastEditorUserId="22726" LastEditDate="2019-01-24T03:44:55.927" LastActivityDate="2019-01-24T03:44:55.927" Title="How can the landing gear fit in the small room in the engine bay on the Tupolev Tu-144?" Tags="&lt;jet-engine&gt;&lt;landing-gear&gt;&lt;supersonic&gt;&lt;tu-144&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27069" PostTypeId="2" ParentId="27068" CreationDate="2016-04-20T06:59:57.440" Score="47" Body="&lt;p&gt;The Tu-144 landing gear rotates 90 degrees when retracted up between the engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Elpwf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Elpwf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://forum.keypublishing.com/showthread.php?19475-December-31st-1968&amp;amp;p=242413#post242413&quot; rel=&quot;noreferrer&quot;&gt;Tu-144 Landing Gear Retraction&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gqTPu.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gqTPu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://www.britmodeller.com/forums/index.php?/topic/46320-1144th-braz-tupolev-tu-144-charger/page-2#entry492570&quot; rel=&quot;noreferrer&quot;&gt;Tu-144 Landing Gear Retraction&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-20T06:59:57.440" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27070" PostTypeId="2" ParentId="27068" CreationDate="2016-04-20T07:01:00.697" Score="49" Body="&lt;p&gt;The Tu-144 uses much smaller wheels than comparably-sized subsonic aircraft. This makes it possible to rotate the &lt;a href=&quot;https://aviation.stackexchange.com/questions/8670/is-there-a-best-number-of-wheels-per-bogie/8672#8672&quot;&gt;gear bogie&lt;/a&gt; sideways towards the middle of the aircraft, so it can be stowed vertically inside the wheel well. Your picture already hints at that:  Note that the gear strut is offset inside the wheel well, so it would leave more space on one side for the gear bogie.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/F4Io1.jpg&quot; alt=&quot;Tupolev Tu-144 landing gear&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Tupolev Tu-144 landing gear (picture &lt;a href=&quot;http://zizis.livejournal.com/206699.html?thread=3749995&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the big drums of the wheel brakes: They were needed to stop the aircraft - the engines had no thrust reversers! Inside are stacks of disc brakes to absorb the energy that comes with a &lt;a href=&quot;http://www.tu144sst.com/techspecs/performance.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;landing speed of 270 km/h&lt;/a&gt;. Also note the unusual sideways arrangement of the scissors link: This way it did not interfere with the rotated wheel bogie. Next clue: The big hydraulic cylinder on the left was used to pivot the bogie around an axis parallel to the direction of flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j1RgR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j1RgR.jpg&quot; alt=&quot;Photo from Tu-144 landing gear test&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture of a photo from Tu-144 landing gear test, including finger print (picture &lt;a href=&quot;http://i752.photobucket.com/albums/xx168/jasper999/P1070980.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). This shows the gear in mid-sequence: The bogie is already rotated and lies sideways, with the gear strut between the wheels. Now the strut pivots forward and up into the wheel well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Requiring complex motion adds more failure modes: On its 59th flight, the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;nofollow noreferrer&quot;&gt;XB-70A&lt;/a&gt; suffered a malfunction of the left gear which left the bogie in the upright position. If you want to know how it was supposed to work, watch &lt;a href=&quot;https://www.youtube.com/watch?v=Rd0mSLv7zoA&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt; from 14:47 on. The picture below is taken from &lt;a href=&quot;https://www.youtube.com/watch?v=WlL1M0ugtWU&quot; rel=&quot;nofollow noreferrer&quot;&gt;this video&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FFHqY.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FFHqY.jpg&quot; alt=&quot;XB-70A after flight 59&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-22T21:08:13.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27071" PostTypeId="2" ParentId="13837" CreationDate="2016-04-20T08:06:12.980" Score="0" Body="&lt;p&gt;Efficiency dictates the optimun rotational speed of propellers and turbines so a gearbox will keep both of them at their best. &lt;/p&gt;&#xA;" OwnerUserId="14574" LastActivityDate="2016-04-20T08:06:12.980" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27072" PostTypeId="1" AcceptedAnswerId="27078" CreationDate="2016-04-20T08:41:25.567" Score="14" ViewCount="1034" Body="&lt;p&gt;As a follow up to &lt;a href=&quot;https://aviation.stackexchange.com/questions/6361/why-doesnt-the-a380-use-its-outboard-thrust-reversers&quot;&gt;why doesn't the A380 use outboard thrust reversers&lt;/a&gt;, if a component is not used in an engine, is it completely removed (hardware, wiring etc etc) or is it just made inoperative?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the A380 wouldn't it make it more difficult to maintain and handle 2 engines which are the same, but with different accessories installed?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't it be risky as there might be human error factors whilst servicing or installing the thrust reversers?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="824" LastEditDate="2019-12-15T04:30:04.203" LastActivityDate="2019-12-16T02:03:44.640" Title="Components on engines, are they removed or blanked out?" Tags="&lt;aircraft-maintenance&gt;&lt;engine&gt;&lt;thrust-reverser&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27073" PostTypeId="2" ParentId="25697" CreationDate="2016-04-20T10:04:34.197" Score="21" Body="&lt;p&gt;While I do not have a specific source to cite, which is always important to reference in regard to any aircraft work, I'm basing this answer on my training as an FAA certified aircraft mechanic.  (There are many more experienced mechanics than myself out there, but alas, none who have done this particular process have arrived yet.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, if you have to work on something that does not already have specified methods from the aircraft manufacturer, the go-to reference is:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;AC43.13 1b/2b - Acceptable Methods, Techniques, &amp;amp; Practices of Aircraft Inspection and Repair&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But I don't know if that volume covers this mishap.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can tell you with some certainty that several inspections will be called for on that aircraft.  The skin and structure of the empennage, of course, but also the main gear will almost certainly require a &quot;&lt;strong&gt;hard landing check&lt;/strong&gt;&quot;, since the airframe was &lt;strong&gt;adversely loaded&lt;/strong&gt; so much that the nose lifted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's every chance that the event will call for a &quot;&lt;strong&gt;tail strike&lt;/strong&gt;&quot; check, which can be extensive.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the aircraft were tipped forward in an uncontrolled fashion, the nose gear may come down quite hard, but the fact that the forces involved would be unknown (compared, say, to a landing touchdown at a known sink rate and aircraft weight,) would also necessitate a hard-landing inspection of the nose gear.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a hard-landing event, the fuselage structure may also be compromised, and relevant areas are also checked, as prescribed by the aircraft's particular inspection and maintenance documents.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an airframe ever does something in an uncontrolled fashion, many inspections will be needed to conservatively account for every possible imagined consequence, and that can cost a great deal of time and money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All this is preamble to the kind of approach a good mechanic will take to a problem that offers little previous experience.  Every &lt;strong&gt;A&amp;amp;P&lt;/strong&gt; can change a tire, balance a control surface, and check for corrosion, but getting an aircraft back on all wheels safely is not often addressed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We know a few things: &lt;br/&gt;&#xA;• The nose gear can support the unloaded nose of the plane (and we know from records what weight range that is). &lt;br/&gt;&#xA;• Dramatic movements are frowned upon. &lt;br/&gt;&#xA;• The aircraft was fine before that last load was introduced. &lt;br/&gt;&#xA;• Personnel safety is a primary concern. (No dangerous heroics!)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things we don't know:  &lt;br/&gt;&#xA;• How hard you can pull down on the nose gear before damaging something (they were not meant for such loads!) &lt;br/&gt;&#xA;• Whether the main gear are at or over their load limit already.  (If people were watching the aircraft's weight and balance figures, we wouldn't be in this mess.) &lt;br/&gt;&#xA;• Whether the fuselage/empennage has been structurally compromised. &lt;br/&gt;&#xA;• How fast/hard the nose might come down with the weight distribution corrected - too fast?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From these things, we can determine what &lt;strong&gt;NOT&lt;/strong&gt; to do: &lt;br/&gt;&#xA;• Pile a bunch of baggage handlers in the nose until it tips back down.  Yay, concussions! &lt;br/&gt;&#xA;• Adding weight (ballast) in general. (Will the airframe be damaged further?) &lt;br/&gt;&#xA;• Haul downward on the nose with a winch. (Don't tear the nose gear off!) &lt;br/&gt;&#xA;• Jack up the tail from the rear. (We don't know if it will hold.  Probably, but we don't take chances.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Variables that could be leveraged: &lt;br/&gt;&#xA;• Can the cargo be winched back towards the front without endangering anyone? &lt;br/&gt;&#xA;• Does this model (&quot;type&quot;) have fore and aft fuel tanks in the main fuselage, and if so, can fuel be moved between them (or pumped out) for weight shift, in safety?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We're left with two primary goals: &lt;br/&gt;&#xA;• Decrease the weight moment behind the mains in a controlled fashion, hopefully without adding any weight to the airframe. &lt;br/&gt;&#xA;• Do not let the nose fall uncontrolled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My approach would resemble the following, depending on equipment available (or that could be found in the local region):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Provide safe support under the nose of the aircraft that can support the normal full weight of the nose of the aircraft.  We want to ensure the nose cannot come down without our say-so.  A sling is ideal, and the airframe manufacturer will have specifications on how to lift and support the airframe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a comment, @TomMcW provided a nice linked visual in this YouTube video: &lt;br/&gt;&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/GNP8epdbIi0?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As seen in the video, the best option would be an overhead crane, with a sling approved for lifting that airframe wrapped under the forward fuselage.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's a more extreme example of using a sling to lift an aircraft:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/a15xC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/a15xC.jpg&quot; alt=&quot;Zero-G Airbus A300 being lifted at Cologne Bonn Airport&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the aircraft is in a stable support with minimized risk of unexpected movement, the next phase is to &lt;strong&gt;UN&lt;/strong&gt;weight the rear, in the safest way we can.  That might be to pump out fuel from an aft tank, or winch a cargo container slowly forward, or (the least favorite) manually unload items, using as few personnel as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As weight is removed from the rear, the airframe will weigh down the sling.  You can lower the sling in a slow and controlled way, with the main gear &quot;&lt;strong&gt;chocked&lt;/strong&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the nose is down, sorting out the rest of the cargo and fuel will be trivial, as flight crew can enter and operate internal systems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But one thing I know for sure: that bird ain't flying today!&lt;/p&gt;&#xA;" OwnerUserId="14575" LastActivityDate="2016-04-20T10:04:34.197" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27074" PostTypeId="1" CreationDate="2016-04-20T10:17:20.827" Score="2" ViewCount="75" Body="&lt;p&gt;One can see  jet trails behind an airplane. I know that they form because of rapid condensation of Jet exhaust. But I can't figure out why some remain for too long time (hence, longer) while  some are smaller and disappear rapidly.  Does this depend on height of airplane or some other parameter ? &lt;/p&gt;&#xA;" OwnerUserId="13652" LastEditorUserId="13197" LastEditDate="2016-04-20T10:27:46.000" LastActivityDate="2016-04-20T10:27:46.000" Title="Why are some jet trails longer and some shorter?" Tags="&lt;contrails&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-04-20T11:52:42.367" ContentLicense="CC BY-SA 3.0" />
  <row Id="27075" PostTypeId="2" ParentId="26591" CreationDate="2016-04-20T19:00:35.450" Score="5" Body="&lt;p&gt;I would agree with the other comments, in that I don't think the extreme buffeting could be caused by out-of-sync props. Maybe if you lost a chunk of a blade and you had out-of-balance props, but that's a bit different. Or if one of the props came WAY out-of-sync. But I know nothing of the Orion aerodynamics or engineering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My twin experience has been more of the light piston and turboprop variety, but I can tell you that out-of-sync props produce a &quot;whah whah whah&quot; sound that will drive you absolutely bonkers. As soon as I was straight and level, I'd match rpms/prop pitch on my engines (or turn on the prop sync) to get rid of the noise. I never wanted to try it long enough, but apparently acoustic oscillation like that can cause serious fatigue. And I would imagine that long-term exposure can't be good for the airframe. &lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2016-04-20T19:00:35.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27076" PostTypeId="1" CreationDate="2016-04-20T21:35:57.983" Score="8" ViewCount="6026" Body="&lt;p&gt;I observed a helicopter hovering over a residential area/houses for more than 20-30 minutes. I would guesstimate about 500 feet altitude or more for the helicopter. The low altitude and long duration of the hovering created lots of what I would call unpleasant &quot;noise pollution&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the FAA minimum allowed altitude for helicopters over a residential area?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;re &quot;possible duplicate&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;@fooot I already googled and read that entire question. That question is asking about &quot;when is a Helicopter legally allowed by FAA to fly below the FAA's minimum allowed safe altitude?&quot; and that question is even more specific to a specific situation observed by the OP. They both have wording that talks about minimum altitude but are not the same question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As others have noted in the comments, they agree this is not a duplicate.&lt;/p&gt;&#xA;" OwnerUserId="7955" LastEditorUserId="62" LastEditDate="2016-04-24T10:10:01.380" LastActivityDate="2018-10-16T21:54:04.097" Title="What is the minimum allowed altitude for helicopters over a residential area in the US?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;helicopter&gt;&lt;altitude&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27077" PostTypeId="2" ParentId="27076" CreationDate="2016-04-20T21:56:48.050" Score="4" Body="&lt;p&gt;It depends on where it is.&lt;/p&gt;&#xA;&lt;p&gt;A &lt;em&gt;residential area/houses&lt;/em&gt; may or not be &amp;quot;congested&amp;quot; -- that term is not defined. But we typically use 500 feet for helis.&lt;/p&gt;&#xA;&lt;p&gt;When hovering in an area for a specific purpose, such as photo shoots or other surveillance operation, or for some other operational reason, then we can use a lower altitude.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Sec. 91.119&lt;/p&gt;&#xA;&lt;p&gt;Minimum safe altitudes: General.&lt;/p&gt;&#xA;&lt;p&gt;Except when necessary for takeoff or landing, no person may operate an&#xA;aircraft below the following altitudes:&lt;/p&gt;&#xA;&lt;p&gt;(a) Anywhere. An altitude&#xA;allowing, if a power unit fails, an emergency landing without undue&#xA;hazard to persons or property on the surface.&lt;/p&gt;&#xA;&lt;p&gt;(b) Over congested&#xA;areas. Over any congested area of a city, town, or settlement, or over&#xA;any open air assembly of persons, an altitude of 1,000 feet above the&#xA;highest obstacle within a horizontal radius of 2,000 feet of the&#xA;aircraft.&lt;/p&gt;&#xA;&lt;p&gt;(c) Over other than congested areas. An altitude of 500 feet&#xA;above the surface, except over open water or sparsely populated areas.&#xA;In those cases, the aircraft may not be operated closer than 500 feet&#xA;to any person, vessel, vehicle, or structure.&lt;/p&gt;&#xA;&lt;p&gt;(d) Helicopters,&#xA;powered parachutes, and weight-shift-control aircraft. If the&#xA;operation is conducted without hazard to persons or property on the&#xA;surface--&lt;/p&gt;&#xA;&lt;p&gt;(1) A helicopter may be operated at less than the minimums&#xA;prescribed in paragraph (b) or (c) of this section, provided each&#xA;person operating the helicopter complies with any routes or altitudes&#xA;specifically prescribed for helicopters by the FAA; and&lt;/p&gt;&#xA;&lt;p&gt;(2) A powered&#xA;parachute or weight-shift-control aircraft may be operated at less&#xA;than the minimums prescribed in paragraph (c) of this section.]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-04-20T21:56:48.050" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27078" PostTypeId="2" ParentId="27072" CreationDate="2016-04-20T22:28:28.360" Score="17" Body="&lt;p&gt;&lt;strong&gt;Short answer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reverser is not installed on the outer engines. As the linked question mentions: This allows to lighten the engines, this also prevents any unwanted and hazardous opening in flight as well as the costly check time for an unused feature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reverser used on the A380 is a &lt;em&gt;cold flow&lt;/em&gt; type. It is merely part of the engine by itself. It is actually integrated in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Nacelle&quot; rel=&quot;nofollow noreferrer&quot;&gt;nacelle&lt;/a&gt; structure channeling the bypass cold flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engine should be usable in all four nacelles, the nacelles themselves cannot be swapped as they provide the reverser. The answer to &lt;a href=&quot;https://aviation.stackexchange.com/q/68026/3201&quot;&gt;this question&lt;/a&gt; seems to confirm this possibility.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Principle&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thrust reversal on this aircraft type consists in opening the bypass duct sideways, blocking the bypass flow in the duct and redirecting it through the opening. The opening is created by sliding the aft section of the nacelle case to expose a set of vanes. The blocked flow now escapes sideways and is guided forward by the vanes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/nt5FA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/nt5FA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Principle of cold flow thrust reverser (&lt;a href=&quot;http://lessonslearned.faa.gov/Lauda/Lauda_ThrustReverser_pop_up.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XDSuq.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XDSuq.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Thrust reverser on the A380 (&lt;a href=&quot;https://aviation.stackexchange.com/questions/6361/why-doesnt-the-a380-use-its-outboard-thrust-reversers&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Engine, reverser, nacelle&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The A380 is equipped with Trent 900 from Rolls-Royce or GP7200 from Engine Alliance. The thrust reversers are made by a different provider, &lt;a href=&quot;http://www.aircelle.com/nacelle-systems/nacelle-systems-long-range-aircraft/airbus-a380-nacelle-systems&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airbus-Aircelle&lt;/a&gt; (part of Safran), which also manufactures the nacelles. This is because the thrust reverser is really integrated in the nacelle rather than linked to the engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Trent 900&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reverser is in the cold / bypass flow behind the fan section which is the engine section with the largest diameter (in the Trent 900, about 3m!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zhKNX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zhKNX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Hot flow, cold flow and reversed flow in a Trend XWB (similar to 900).&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;Based on &lt;a href=&quot;http://www.aero-news.net/index.cfm?do=main.textpost&amp;amp;id=1ea393e1-6eee-4320-801c-b644c1f1ccc1&quot; rel=&quot;nofollow noreferrer&quot;&gt;RR picture&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cold flow duct (fan duct) is similar in both versions of the nacelles.  The duct is fenced by two semi-annular walls behind the &lt;a href=&quot;https://aviation.stackexchange.com/questions/25877/in-a-turbofan-what-holds-the-spinning-axis&quot;&gt;fan frame&lt;/a&gt;, where the flow is rushed by the fan. This is called a double D-duct (in reference to the shape of the semi-duct).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two D-ducts of an inner nacelle contain the reverser panes and their associated components. This version is named the &lt;em&gt;thrust reverser unit&lt;/em&gt; (TRU). The other version without the reverser is the &lt;em&gt;fixed fan duct&lt;/em&gt; (FFD), it doesn't slide.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;TRU&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T87J8.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T87J8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;The TRU is visible behind the fan section, &lt;a href=&quot;https://www.reussirmavie.net/Delphine-formatrice-en-maintenance-sur-A380_a679.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the image above, the two halves of the TRU are open. Note the outer wall of the duct has some thickness, contrary to the FFD wall (see next). This volume is used to host the mechanism needed to move the panels rerouting the flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The inner wall prevents all the flow to reach the core and the components and pipes around it, in order to not create damage or drag and heat. However a limited quantity of air is still directed toward the core for cooling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More easy to see on this CG view:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d7Pri.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d7Pri.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Trent 900 duct and reverser. Based on &lt;a href=&quot;http://www.turbosquid.com/index.cfm&quot; rel=&quot;nofollow noreferrer&quot;&gt;TurboSquid&lt;/a&gt; models.&lt;/sup&gt;&lt;br&gt;&#xA;&lt;sup&gt;Top: &lt;a href=&quot;http://www.turbosquid.com/3d-models/trent-900-jet-engine-max/786059&quot; rel=&quot;nofollow noreferrer&quot;&gt;3D model&lt;/a&gt; by BlueGreen. Bottom: Another &lt;a href=&quot;http://www.turbosquid.com/3d-models/3d-trent-900-jet-engine/789132&quot; rel=&quot;nofollow noreferrer&quot;&gt;excellent 3D model&lt;/a&gt; by BlueGreen.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;FFD&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Left D-duct highlighted in blue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bicD9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bicD9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Nacelle duct for cold flow. Based on image by &lt;a href=&quot;http://www.airliners.net/search/photo.search?photographersearch=Benny%20Zheng&quot; rel=&quot;nofollow noreferrer&quot;&gt;Benny Zheng&lt;/a&gt; on &lt;a href=&quot;http://www.airliners.net/photo/Qantas/Airbus-A380-842/1815483/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-12-16T02:03:44.640" LastActivityDate="2019-12-16T02:03:44.640" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="27079" PostTypeId="2" ParentId="23990" CreationDate="2016-04-21T01:52:05.427" Score="17" Body="&lt;p&gt;I agree, Malaysian MH132 was a Non-Event.   If the pilots had any concerns over the slight variation in their routing, they should have mentioned it before they loaded it into the Flight Management System (FMS).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I currently fly long haul B777 for a major airline. I can't speak for others, but at the airline I work for &lt;strong&gt;we do many &quot;gross error checks&quot;&lt;/strong&gt;. Some are done in flight planning, some during the loading of the FMC, and some are done during the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;While still in the flight planing area&lt;/strong&gt;, the Captain and First Officer will look at the total routing in regards to wind, temperature, turbulence, volcanic activity, etc.  Often a call is made to the dispatcher who generated the Operational Flight Plan (OFP) to discuss the routing, expected levels of turbulence, and fuel reserves.  About 20% of the time the Captain will request a slight change to the routing or additional fuel be added.  A new OFP is then generated and it will be designated &quot;Release 2&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both the flight plan route and ICAO flight plan route are printed on the OFP and we compare the two.  I have never found an error in the 17 years I have been doing it, but we still do it every time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once the Captain, FO and augment pilots ALL agree, the OFP is officially accepted and we head to the aircraft. (up to 4 pilots on Ultra Long Haul flights)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When we get to the aircraft&lt;/strong&gt; we run though the basic preflight checks, and then the flight plan is downloaded to the FMS using the Aircraft Communications Addressing and Reporting System (ACARS) digital datalink system. The departure runway and SID is also loaded at this time.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before we &quot;activate&quot; and &quot;execute&quot; the routing, the Pilot Monitoring (PM) reads the entire FMC routing and the Pilot Flying (PF) compares it to the OFP.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After runway takeoff performance data is loaded we then check the &quot;Legs&quot; page of the FMC for a logical sequence of legs. We generally just check to make sure there are no course reversals on the various legs of the route.  If there are any user defined waypoints (Lat/Long waypoints) we perform bearing and distance checks of  the FMC against the OFP. This is done with the the Heading Reference switched to TRUE heading instead of Magnetic for more accurate numbers.  These bearing and distance checks are not done for &quot;Named&quot; waypoints, only Lat/Long waypoints. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind data is then requested and then loaded via ACARS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next is a check of the FMC distance compared to both the OFP distance and Great Circle Route distance.  The FMC distance is almost always somewhere between the OFP distance and GCR distance. This check is one sure way to spot a routing entry error.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally a check of the FMC and OFP predicted fuel over destination is done. If there is a large difference, it means either the routing or winds were incorrectly entered. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Once airborne&lt;/strong&gt; there are more checks:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the old days before GPS we would check the accuracy of the Inertial Navigation System (INS) as we approached the coast for any over water flight. This was usually done using a VOR/DME fix. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once airborne we again check bearing and distance as we approach each user defined waypoint (Lat/Long waypoint). Once past the waypoint by about 5 mins we then plot our current Lat/Long on a plotting chart to insure we are still on course.  &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-21T02:01:11.183" LastActivityDate="2016-04-21T02:01:11.183" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27080" PostTypeId="1" CreationDate="2016-04-21T06:08:52.507" Score="8" ViewCount="10419" Body="&lt;p&gt;I was looking for A319neo, A320neo and A321neo IATA code all over the net but I could't find it, can someone help me with this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(As of 9 March, 2018, the answer with the highest up-vote count (from April 2016) states &quot;will likely be the same as&quot;. A more definitive answer should be available now.)&lt;/p&gt;&#xA;" OwnerUserId="14583" LastEditorUserId="2171" LastEditDate="2018-03-09T17:19:23.950" LastActivityDate="2018-03-15T12:26:24.270" Title="What is the IATA code for the A320neo family?" Tags="&lt;airbus-a320&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27081" PostTypeId="2" ParentId="27041" CreationDate="2016-04-21T06:47:33.587" Score="3" Body="&lt;p&gt;If some parts of the airfoil create lift and others a downforce, the center of pressure can be outside of the airfoil's chord at low lift coefficients. This condition is fulfilled for cambered airfoils, airfoils with a deflected flap and especially for rear loading airfoils, which have low camber in the front and high camber in the rear part. Supercritical airfoils meet this last condition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In airfoil theory, an airfoil creates lift and a moment, because the lift is assumed to attack at the quarter chord point. This point is special because here the moment coefficient does not change with the angle of attack (at least in the inviscid, linear potential theory, which is sufficiently close to reality at large Reynolds numbers to be useful). In reality, positive camber will cause the resulting lift force to act aft of the quarter chord point, and the pitching moment is negative. When lift becomes small and the pitching moment stays constant, the lever arm of that small lift needs to become large to achieve the same moment, and this is when the center of pressure can slip out of the airfoil's chord.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below you see the result from XFRL5 V6.0.5. I plotted the local center of pressure as a green line. It's elevation over the plane of the wing shows the amount of lift locally created, and the location in streamwise direction shows that it leaves the local chord when lift becomes low. Note that when moving out in spanwise direction the location jumps from far aft of the airfoil to far ahead when the local lift turns negative. At the point of no local lift you have a division by zero error, patched over here by a straight connection between the results from the single panels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n99j8.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n99j8.png&quot; alt=&quot;Location of the local center of pressure on a swept wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Location of the local center of pressure on a swept wing (own work).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When angle of attack is increased, all additional lift has the Birnbaum distribution, so the local center of pressure moves towards the quarter-chord location.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-04-23T18:33:36.377" LastActivityDate="2016-04-23T18:33:36.377" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27082" PostTypeId="2" ParentId="27080" CreationDate="2016-04-21T07:14:54.293" Score="8" Body="&lt;p&gt;The IATA three letter code for the Neo will likely be the same as for the regular model. &#xA;Unfortunately the IATA code list is copyrighted, and I can't find a public document that confirms it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The more commonly used ICAO type designator, a four letter code can be found in  &lt;a href=&quot;http://www.icao.int/publications/DOC8643/Pages/default.aspx&quot;&gt;ICAO doc 8643&lt;/a&gt;. It contains a list of all common aircraft and their codes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ICAO type designator for the neo will be the same as for the regular versions. So A319, A320 and A321. Only if the performance of the Neo aircraft significantly differs from the originals, then a dedicated designator will be created.&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-04-21T08:16:22.443" LastActivityDate="2016-04-21T08:16:22.443" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27083" PostTypeId="1" AcceptedAnswerId="27090" CreationDate="2016-04-21T08:23:24.277" Score="14" ViewCount="2592" Body="&lt;p&gt;I asked this as a comment in &lt;a href=&quot;https://aviation.stackexchange.com/questions/27064/can-i-bring-a-person-with-me-while-getting-landing-current-if-theyre-a-licensed&quot;&gt;this question&lt;/a&gt;, but I thought it was worth asking properly to preserve it for future Aviation.SE generations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there any sort of permission required to fly from the right seat of an aircraft? If I've done all of my training on the left side of a C172 is there anything stopping me from deciding one day to stick a passenger in there and fly with my right hand?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I acknowledge that for experienced pilots there shouldn't really be a safety risk in doing this, but many light aircraft displays/instrumentation are designed for the pilot being in the left seat. &lt;/p&gt;&#xA;" OwnerUserId="3746" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-21T15:46:40.170" Title="Is an approval required to fly from the right seat?" Tags="&lt;cockpit&gt;&lt;casa-regulations&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27084" PostTypeId="1" CreationDate="2016-04-21T08:39:56.950" Score="1" ViewCount="267" Body="&lt;p&gt;According to the TSO 151c: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Speed. Airspeed or groundspeed must be included in the logic that determines basic&#xA;  GPWS alerting time for “excessive closure rate to terrain” and “flight into terrain when not in&#xA;  landing configuration” to allow maximum time for the flight crew to react and take corrective&#xA;  action.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As I understand for &quot;flight into terrain when not in landing configuration&quot; modes, in the guides corner speeds are given as from 190 KTS to 250 KTS. I can understand the calculations dependency on airspeed but do you have any idea how these speeds are selected? Are they regulated by FAA or EASA? As far as i know, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§91.117   Aircraft speed.&#xA;  (a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;but why 190 KTS? Is there any speed limits that should be obeyed for approaches and landing?&lt;/p&gt;&#xA;" OwnerUserId="11948" LastEditorUserId="1467" LastEditDate="2016-04-21T08:53:17.847" LastActivityDate="2016-04-21T08:53:17.847" Title="Why does TAWS alert depends on airspeed?" Tags="&lt;landing&gt;&lt;approach&gt;" AnswerCount="0" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27085" PostTypeId="1" AcceptedAnswerId="27093" CreationDate="2016-04-21T08:53:38.043" Score="5" ViewCount="416" Body="&lt;p&gt;Take GFC700 for example, when autopilot (or flight director) engaged, the lateral mode falls into&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ROL, HDG, GPS, VOR, VAPP, LOC, BC, ...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and the vertical model has to fall into&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;PIT, ALT, FLC, VS, VPATH, GS, GP, ...&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;When disengaged (or temporarily by CWS), a pilot has to hand-fly both axes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering if this is universal across all autopilot systems. Is there any autopilot that I may engage one axis and hand-flying the other. e.g. The autopilot only holds altitude and I may roll the yoke without any counter pressure. Are there regulations or purely from technical consideration?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="12019" LastEditDate="2016-04-22T04:18:35.767" LastActivityDate="2016-04-22T04:18:35.767" Title="Is it possible to disengage only one axis of a two-axis autopilot?" Tags="&lt;autopilot&gt;&lt;fms&gt;&lt;flight-director&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27088" PostTypeId="2" ParentId="27085" CreationDate="2016-04-21T10:53:31.273" Score="2" Body="&lt;p&gt;On some autopilots it is clearly possible to disconnect each axis separately as evidenced by the accident of &lt;a href=&quot;https://en.wikipedia.org/wiki/Aeroflot_Flight_593&quot; rel=&quot;nofollow&quot;&gt;Aeroflot flight 593&lt;/a&gt;. On others, including the ones used on later Airbus models (A320+; the accident was A310), it is not.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-04-21T10:53:31.273" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27090" PostTypeId="2" ParentId="27083" CreationDate="2016-04-21T13:29:24.347" Score="6" Body="&lt;p&gt;As Ron mentions in the comments here in the US it is not illegal by any specific regulations however... &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most GA aircraft (the smaller ones at least) only have a single set of instruments that reside in front of the left seat as you mention in the question. Lets say hypothetically you were flying right seat and something went wrong. Due to the angle of view you were not able to read an instrument and this lead to an accident. Lets say you lose your primary CDI/Glide Slope while flying an ILS approach and you need to use one on the far side of the cockpit. For some reason you are alone and in the right seat. If an accident did occur as a result of this you may be able to be held to &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=3d9bc1f1cdecc6e1bb0581c301c38b91&amp;amp;mc=true&amp;amp;node=se14.2.91_113&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;§91.13   Careless or reckless operation.&lt;/a&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Aircraft operations for&#xA;  the purpose of air navigation. No person may operate an aircraft in a&#xA;  careless or reckless manner so as to endanger the life or property of&#xA;  another.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Since the left seat was open and available for you. But other than that there is no regulation preventing such operation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/users/12623/ron-beyer&quot;&gt;Ron&lt;/a&gt;  posted an &lt;a href=&quot;http://aviationmentor.blogspot.com/2011/01/flying-right-seat.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;excellent article&lt;/a&gt; in the comments below that has at least one quote worth mentioning &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft insurance policies and flying club rules often specify that&#xA;  all flying is to be done from the left seat unless the pilot holds a&#xA;  current flight instructor certificate or has specific authorization.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While this is not an FAA regulation insurance companies or the rental/flight club you get your plane from may stipulate left seat only flying. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-21T15:46:40.170" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27091" PostTypeId="1" CreationDate="2016-04-21T14:13:47.243" Score="6" ViewCount="526" Body="&lt;p&gt;I am working on a flight control computer (Bombardier) where I got a bunch of requirements for steep approaches. All they do is 'engage steep approach' or disengage it after determining if it is safe to engage the steep approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even after engaging the steep approach, if the pilot does not configure the flight properly (throttle, flap, slat settings) then it disengages the steep mode and informs the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After carefully going through the requirements, I did not find anything that the flight control computer does during the steep approach. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;So is all that the flight control computer does during steep approaches to monitor it and display steep engage or disengage messages?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What would a pilot do if steep approach was to disengage when he reached below 200 ft? (Breaking off from steep approaches, I understand, is the result of losing some of the sensors, jamming of actuators etc..). Can a pilot 'go around' even if the altitude drops below 200 ft (decision height of CAT I landing)?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is there a possibility for the aircraft to stall while trying to descend steeply?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="62" LastEditDate="2016-04-21T21:09:14.597" LastActivityDate="2017-10-10T14:46:14.943" Title="What is the role of a flight control computer during a steep approach?" Tags="&lt;flight-controls&gt;&lt;approach&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27093" PostTypeId="2" ParentId="27085" CreationDate="2016-04-21T14:43:09.917" Score="5" Body="&lt;p&gt;Some autopilots found on advanced aircraft can be engaged on selected axis only, for example Boeing 737, 747-200 &amp;amp; MD-11. There are three autopilot indicators on the Boeing autopilots: auto throttle, roll and pitch. Each can be in a different mode.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here a Boeing 737's autopilot roll mode is set to Heading Select (HDG SEL) while the &lt;strong&gt;P&lt;/strong&gt;itch is flown manually (CWS &lt;strong&gt;P&lt;/strong&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pfafB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pfafB.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilot can pull or push the yoke, and the autopilot will roll the aircraft automatically. If the pilot steer the yoke left or right, the roll mode will change to CWS R.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this image below, the pilot is manually &lt;strong&gt;R&lt;/strong&gt;olling the aircraft (CWS &lt;strong&gt;R&lt;/strong&gt;), but the autopilot pitch mode is set to Vertical Speed mode.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/DUB1Q.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DUB1Q.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Later models, such as the Boeing 777, does not have this feature - both pitch and roll modes must be engaged together.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-04-21T18:05:55.070" LastActivityDate="2016-04-21T18:05:55.070" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27095" PostTypeId="1" AcceptedAnswerId="27098" CreationDate="2016-04-21T20:47:14.997" Score="16" ViewCount="1313" Body="&lt;p&gt;I just started to receive instructions to become a glider pilot, yay me! :)&#xA;I (and my instructor) have noticed that I have the tendency to keep the head level (eye-line parallel to horizon) in turns and my instructor says that wouldn't be a good idea, because at some point I won't be able to keep the head level anymore, so I should practice with keeping my head level to the lateral axis of the plane, i.e. inclined together with the bank and eye-line parallel with the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do professional or experienced glider pilots do? Is it maybe a matter of taste? Or should I let go of this tendency because at some point I just can't use horizon and gravity-sensation to orient myself (due to g-forces, spinning, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="2958" LastEditorUserId="2958" LastEditDate="2016-04-21T20:56:03.803" LastActivityDate="2017-01-25T20:10:00.757" Title="Should head stay level or inclined in a bank?" Tags="&lt;glider&gt;" AnswerCount="6" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27096" PostTypeId="2" ParentId="26543" CreationDate="2016-04-21T21:40:12.657" Score="3" Body="&lt;p&gt;I have a partial answer after more research and some help on &lt;a href=&quot;http://www.pprune.org/private-flying/577812-routes-ppl-gliding.html&quot; rel=&quot;nofollow&quot;&gt;pprune&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A Bronze + XC can be used to get a gliding licence, which under the transitional arrangements can be used to obtain a LAPL(S).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory the route from there to a LAPL(S)+TMG  and on to a LAPL(A) TMG is feasible, however the BGA is not an ATO yet and there are very few instructors or examiners around.  This route may be problematic at the moment, but should become easier as time goes on.  There's no reason not to claim the LAPL(A) on the way to a PPL(A) if taking this route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An alternative route is via an NPPL under the transitional arrangements.  After gaining the gliding certificate, a minimum of 10 hours under instruction is needed until reaching the standard for an NPPL SMLG.  After short conversion training, this can then be converted to an NPPL SSEA.  After 6 hours PIC this lot in turn can be traded in for a LAPL(A) SEP+TMG.  Complicated, but overall less hours and my much can be done at a BGA club with a motorglider and instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the straight PPL(A) route with credit, given the statement &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you hold a pilot’s licence for another type of aircraft, except&#xA;  balloons, you will be credited with 10% of your total flight time as&#xA;  PIC up to a maximum of 10 hours&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;it would seem clear that at that some form of licence is needed, and given the gliding licence qualifies for a LAPL(S) anyway, which one is moot.&lt;/p&gt;&#xA;" OwnerUserId="14246" LastEditorUserId="14246" LastEditDate="2016-04-21T21:45:31.170" LastActivityDate="2016-04-21T21:45:31.170" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27097" PostTypeId="2" ParentId="27095" CreationDate="2016-04-21T22:16:49.110" Score="9" Body="&lt;p&gt;I was taught (by multiple instructors) to keep head straight.  During my instrument training, I was told it helped w/spatial disorientation.  During my aerobatic training, my instructor sat behind me and would slap the back of my head if I did not keep it straight during maneuvers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;straight == not tilted, lean back and keep head firmly planted on headrest, do not compensate bank, etc.&lt;/p&gt;&#xA;" OwnerUserId="2536" LastEditorUserId="2536" LastEditDate="2016-04-22T14:36:37.580" LastActivityDate="2016-04-22T14:36:37.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27098" PostTypeId="2" ParentId="27095" CreationDate="2016-04-22T01:42:29.993" Score="23" Body="&lt;p&gt;I am not a glider pilot, but the principle holds for flying any fixed wing aircraft&lt;sup&gt;1&lt;/sup&gt;: you should keep your head level with the aircraft, as you described, not the horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As your instructor explained, there may come—or will come—a time when you are not able to keep your head level with the horizon due to the nature of a particular maneuver or orientation, and that is a practical matter to consider. It is certainly difficult to incline one's head 60° to the side in a steep turn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From my perspective, however, the more important reason is that your frame of reference needs to be &lt;em&gt;the aircraft&lt;/em&gt;. You are used to viewing the world with the ground as your frame of reference; down is down, up is up. As you learn to fly, however, you need to learn a new way to view three dimensional space, or—more specifically—the way you move through that space in the aircraft. It might sound cheesy, but you really need to learn to become one with the aircraft and hold the same perspective regardless of the aircraft's orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, that being said, as you gain experience and develop your skills, you may come to realize that this perspective shift does not always require that your head remain rigidly perpendicular to your shoulders. Rather, it is a matter of perception which will eventually be independent of how your head is oriented relative to the aircraft. At my first flying job I spent much of my time in maneuvering flight and my head was rarely still—much less level with the aircraft. I spent a great deal of time with my head on a swivel, looking up and down, side to side, craning forward to clear into a turn, looking back into the cockpit, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At this stage in your training, however, it is probably important to train to keep your head straight within the aircraft; certainly follow your instructor's instructions, and you should do well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;sub&gt;This probably holds true for rotorcraft as well, or any aircraft for that matter. I am only sharing what I am familiar with.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2017-01-25T20:10:00.757" LastActivityDate="2017-01-25T20:10:00.757" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27099" PostTypeId="1" CreationDate="2016-04-22T03:54:13.247" Score="9" ViewCount="24431" Body="&lt;p&gt;About a week ago, I was flying from Boston to San Juan in an A320 and noticed that the flight was staying at about 42000 feet for the major part of the trip, according to the flight map screen on the plane's entertainment system. That struck me as an unusually high altitude and I am even more surprised now that I have read a little on the subject. I am wondering if that was even possible, or the altitude readout to the entertainment system was simply wrong. The flight proceeded uneventfully in other ways, and was on time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the ceiling altitude for the Airbus A320?&lt;/p&gt;&#xA;" OwnerUserId="14598" LastEditorUserId="15311" LastEditDate="2018-12-29T00:52:08.960" LastActivityDate="2018-12-29T00:52:08.960" Title="What is the ceiling altitude for the Airbus A320?" Tags="&lt;aircraft-design&gt;&lt;airbus-a320&gt;&lt;altitude&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27100" PostTypeId="5" CreationDate="2016-04-22T04:20:15.360" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-04-22T04:20:15.360" LastActivityDate="2016-04-22T04:20:15.360" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27101" PostTypeId="4" CreationDate="2016-04-22T04:20:15.360" Score="0" Body="An FMS is a specialized computer system that automates a wide variety of in-flight tasks, reducing the workload on the flight crew. A primary function is in-flight management of the flight plan. [Wikipedia]" OwnerUserId="12019" LastEditorUserId="511" LastEditDate="2016-04-22T06:07:43.717" LastActivityDate="2016-04-22T06:07:43.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27102" PostTypeId="1" AcceptedAnswerId="27103" CreationDate="2016-04-22T07:14:11.083" Score="2" ViewCount="9307" Body="&lt;p&gt;One of my coworkers says his chemistry teacher told them (a long time ago) that kerosene has a higher octane value than gasoline. My understanding was always that aviation gasoline has octane value above 120, but it is really gasoline, while kerosene is more like diesel fuel. What is the truth?&lt;/p&gt;&#xA;" OwnerUserId="6963" LastActivityDate="2016-04-22T07:53:01.380" Title="Does kerosene have a higher octane value than gasoline?" Tags="&lt;fuel&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2016-04-22T14:20:35.907" ContentLicense="CC BY-SA 3.0" />
  <row Id="27103" PostTypeId="2" ParentId="27102" CreationDate="2016-04-22T07:53:01.380" Score="7" Body="&lt;p&gt;Octane rating is a measure of how well a fuel resists detonation, which is the premature explosion of fuel in an engine cylinder before the spark is applied. This is relevant for spark ignition engines which use gasoline type fuels like avgas. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Kerosene has a very low octane rating, somewhere around 15, and isn't a good fuel for spark ignition engines as it would detonate on compression. This is why kerosene and diesel are used in diesel cycle engines which rely on the spontaneous detonation of fuel under pressure. Kerosene is not typically used in internal combustion engines, however in aviation there are turbo-diesel piston engines which run on Jet-A1.&lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-04-22T07:53:01.380" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27104" PostTypeId="2" ParentId="27095" CreationDate="2016-04-22T09:52:22.413" Score="5" Body="&lt;p&gt;Level with the wings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you keep level with the horizon then you are not maintaining an even lookout all round for a start and when you find yourself in a stack of other gliders in a thermal you need to keep a good lookout even with FLARM. &#xA;In addition what the head does the body tends to follow and so you may find yourself unintentionally decreasing the bank angle to match your head and then slipping out of the turn. &lt;/p&gt;&#xA;" OwnerUserId="14127" LastActivityDate="2016-04-22T09:52:22.413" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27105" PostTypeId="1" CreationDate="2016-04-22T10:13:02.987" Score="3" ViewCount="1252" Body="&lt;p&gt;During CAT IIIA/IIIB approach where the decision height is 50 ft/0 ft, if the Runway Visual Range requirement for the approach is not met, what is a pilot to do?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, 50 ft (or even 100 ft?) seem so low enough  that a go around can not be initiated. Unless the pilot knows the RVR beforehand how can he be sure to perform CAT III approach?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="1467" LastEditDate="2016-04-22T14:13:48.523" LastActivityDate="2016-04-22T18:40:56.613" Title="Is the Runway Visual Range (RVR) communicated to the pilots?" Tags="&lt;runways&gt;&lt;approach&gt;&lt;go-around&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27106" PostTypeId="2" ParentId="27105" CreationDate="2016-04-22T12:33:44.847" Score="4" Body="&lt;p&gt;Pilots get the RVR values either from weather reports or directly from ATC. RVR also shows up on ATIS reports when visibility drops to less than 1 mile. ATC will have a realtime readout of RVR and can communicate these values to pilots at any time by radio. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC RVR display&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/VbqfR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VbqfR.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://mtechsystems.com/corporation/company-news-2012.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://mtechsystems.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The CAT III approach should only be commenced if the ceiling and RVR values meet the minimum for the approach in use and for the current aircraft equipment status. Some airlines will have their own minimums which can differ from the published CAT III minimums. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots will often ask for the latest ceiling and RVR values while doing the approach. ATC will also announce any changes or reduction in ceiling or RVR values while aircraft are on approach. If the new values are below limits, the crew should commence a go-around. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A go-around can be done from any altitude and the wheels can touch the runway during the go-around. Low atlitude, &quot;Low Energy&quot; go-arounds are practiced during re-current Simulator training.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-22T18:40:56.613" LastActivityDate="2016-04-22T18:40:56.613" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27107" PostTypeId="2" ParentId="9223" CreationDate="2016-04-22T16:06:32.367" Score="7" Body="&lt;p&gt;From an engineering perspective, concrete is modeled as a rigid pavement and asphalt is a flexible pavement.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concrete is harder and more brittle than asphalt. Concrete generally cannot tolerate significant ground movement without cracking.  The addition of steel reinforcing to concrete can help to mitigate concrete's brittleness to some extent, but Jan is correct in saying that once concrete has cracked or spalled, it cannot be easily repaired.   Generally an entire panel must be completely replaced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Asphalt is less expensive than concrete to install initially but the surface will degrade over time due to the evaporation of volatile aromatic hydrocarbons so must be maintained on a regular schedule whereas a concrete surface requires no regular maintenance.  Asphalt is a weaker material than concrete but can be made to support equal loads by constructing a thicker pavement.  Asphalt will soften under high temperatures so warm climates can be a problem for asphalt.  Because asphalt is flexible it is a better choice over soils that are prone to movement or over soils that would be too expensive to treat to raise their bearing capacity.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Concrete reflects light better than asphalt so will have better visibility at night.  For highways, asphalt is a quieter surface than concrete although that would not be a consideration for aviation purposes.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The choice of whether to use concrete or asphalt must consider all these variables of initial cost vs. long term maintenance, soil condition, visibility, climate, local budgetary considerations, local availability of materials, etc.  Each installation will be different.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have supervised drilling cores from the runway and taxiways at San Diego International Airport (KSAN).  It has alternating layers of concrete and asphalt in some locations although the top surface is asphalt.  The total thickness varies but is generally at least 18&quot; thick.  The airport sits on the former outlet to the San Diego River and is only a short distance from the bay, so the sub soils are weak alluvial silts that are saturated a short distance below grade.  Yet the taxiways are mostly concrete.  Go figure.  &lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2016-04-22T16:06:32.367" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27108" PostTypeId="2" ParentId="27095" CreationDate="2016-04-22T17:11:30.790" Score="2" Body="&lt;p&gt;As others have said, keep your head straight in reference to the aircraft.  To add to Ron's comment, head leaning can lead to coriolis illusion.  &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/tLmpGca6QDY?start=463&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="651" LastActivityDate="2016-04-22T17:11:30.790" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27109" PostTypeId="1" AcceptedAnswerId="27111" CreationDate="2016-04-22T17:35:29.117" Score="30" ViewCount="28928" Body="&lt;p&gt;I'm not a helicopter pilot. The way I understand it, helicopter pilots have to constantly make small adjustments to make a helicopter hover steadily at a certain point in space, just like fixed wing pilots flying in close formations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any systems which, when engaged, will measure the helicopter's movement with gyroscopes and accelerometers, and automatically compensate for small deviations?&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="5517" LastEditDate="2017-08-30T15:18:20.847" LastActivityDate="2019-01-02T05:44:15.057" Title="Do helicopters have an auto hover system?" Tags="&lt;helicopter&gt;&lt;autopilot&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27110" PostTypeId="2" ParentId="27109" CreationDate="2016-04-22T18:34:05.973" Score="15" Body="&lt;p&gt;Yes.  Some helicopters, especially rescue, have auto-hover.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Thk58yD6QCI?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More to follow...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I tried to find some videos for you, especially of the Bell 412 auto hovering on YouTube which seems to have been removed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AW-101, Bell 412, Bell 525, S92 and others have this capability.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-04-22T18:51:17.093" LastActivityDate="2016-04-22T18:51:17.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27111" PostTypeId="2" ParentId="27109" CreationDate="2016-04-22T20:55:07.297" Score="32" Body="&lt;p&gt;Yes, advanced flight directors and autopilots for helicopters can control the aircraft in all axes, and often they have modes for hovering built in, including maintain altitude, lateral veloctiy hold, hover, and/or autolevel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hovering is difficult because it requires more complex controls than maintaining altitude in an airplane.  Helicopters have a different set of control axes than fixed-wing aircraft.  Fixed wing aircraft are controlled in pitch, roll, and yaw, with thrust as an extra variable.  On a helicopter the flight path is controlled through cyclic (roll and pitch), collective, and throttle, with the anti-torque pedals as well to control yaw.  Hovering the aircraft requires controlling of the cyclic to keep the aircraft over its target with no lateral movement, and collective and throttle to maintain constant altitude, although the exact procedures are a little more complex. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While not present on low-end helicopters due to a combination of complexity and lack of necessity, advanced autopilots for helicopters do exist.  Like on other aircraft, there is a wide variety in autopilots between simple functions to maintain attitude (often called one or two-cue guidance depending on the number of axes used) to complex FMS-integrated three-axis modes (which would be &quot;three-cue&quot; guidance). The FAA &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/&quot;&gt;Helicopter Flying Handbook&lt;/a&gt; states, for example, that  &quot;The most advanced autopilots can fly an instrument approach to a hover without&#xA;any additional pilot input once the initial functions have&#xA;been selected.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Agusta AW139 helicopter that I'm familiar with (although I'm not a pilot), they have several modes that provide this functionality:  &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;an altitude mode to maintain a given altitude &lt;/li&gt;&#xA;&lt;li&gt;an altitude acquire mode to smoothly reach a desired altitude&lt;/li&gt;&#xA;&lt;li&gt;an autolevel mode to level off at the end of an approach segment&lt;/li&gt;&#xA;&lt;li&gt;a lateral velocity hold mode to maintain slow lateral motion or no lateral motion&lt;/li&gt;&#xA;&lt;li&gt;more exotic search and rescue modes providing capabilites to transition to a hover, mark-on-target descents to predefined altitutdes, etc.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;A traditional hover would be achieved by combining a low lateral velocity mode with a zero vertical speed mode like altitude or autolevel.&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="14613" LastEditDate="2016-04-22T21:06:40.363" LastActivityDate="2016-04-22T21:06:40.363" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27112" PostTypeId="1" AcceptedAnswerId="27119" CreationDate="2016-04-22T21:21:29.897" Score="12" ViewCount="3893" Body="&lt;p&gt;I often see small aircraft flying at a low altitude around beaches and the like with banner advertisements trailing behind them on a rope sort of structure. I have a few questions about them:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What sort of permissions does it require (FAA) ?  &lt;/li&gt;&#xA;&lt;li&gt;Is this hazardous in any way (I believe there would be some&#xA;restrictions on this type of flight but is there an inherent danger&#xA;involved in such flights) ?&lt;/li&gt;&#xA;&lt;li&gt;Are there any limits as to what altitude they are allowed to reach and&#xA;any restricted air space that they are only allowed to fly in ?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="2862" LastEditorUserId="62" LastEditDate="2016-04-23T13:43:26.603" LastActivityDate="2019-09-24T03:25:12.180" Title="What are the regulations involved in aerial advertising?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27114" PostTypeId="1" AcceptedAnswerId="27120" CreationDate="2016-04-23T01:08:48.253" Score="15" ViewCount="7431" Body="&lt;p&gt;In this photo, there is a 757 at Narita Airport with a tube connected to the belly. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/ISvaf.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ISvaf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.airliners.net/photo/Delta-Air-Lines-%28Northwest-Airlines%29/Boeing-757-251/1603286/L/&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;br&gt;&#xA;The tube is in the middle of the plane. &#xA;There is a &lt;a href=&quot;https://aviation.stackexchange.com/questions/21688/what-is-this-every-time-i-deplane-its-put-onboard/21901#21901&quot;&gt;similar question&lt;/a&gt; about this tube, but here it seems to be connected to the ground and not to the jet bridge.&#xA;Does anybody know something about this tube?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2020-12-29T16:16:04.173" Title="What is this tube connected to a 757 for?" Tags="&lt;airliner&gt;&lt;boeing-757&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27115" PostTypeId="2" ParentId="27114" CreationDate="2016-04-23T01:15:52.240" Score="7" Body="&lt;p&gt;The yellow tube you see in the photo is &quot;in-ground air conditioning&quot;. It is more common to see it connected to the bridge. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-23T11:28:16.823" LastActivityDate="2016-04-23T11:28:16.823" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27117" PostTypeId="2" ParentId="25308" CreationDate="2016-04-23T05:51:34.733" Score="10" Body="&lt;p&gt;Assuming there is no &lt;strong&gt;STC&lt;/strong&gt; (&quot;Supplemental Type Certificate&quot;) that addresses this as an existing &lt;em&gt;modification&lt;/em&gt;, the answer, in terms of acceptable aircraft airworthiness, is a hard &lt;strong&gt;&lt;em&gt;no&lt;/em&gt;&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Can the aircraft fly&quot; is a tricky question in some ways, but dead-easy in others.  And remember: a helicopter is a thousand moving parts spinning wildly around an oil leak.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking at it from a flight physics and dynamics perspective, as a result of a mishap/damage in flight, (assuming no other problems like a damaged rotor or loss of hydraulic fluid,) and whether you can control the aircraft safely to the ground, a skilled pilot &lt;strong&gt;rated&lt;/strong&gt; for this aircraft &quot;&lt;strong&gt;type&lt;/strong&gt;&quot; would probably be able to wrestle the aircraft to a safe landing.  The &lt;strong&gt;main rotor&lt;/strong&gt; does the work of holding the helo aloft, and the &lt;strong&gt;tail rotor&lt;/strong&gt; holds the attitude steady against the torque of the main rotor.  The &lt;strong&gt;stabilator&lt;/strong&gt; (stabilizer-elevator combined surface) does not contribute to total lift in hover, although it may affect lift in forward flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, any mission the helo had been in the midst of should be immediately abandoned for the sake of making the landing.  Even if you were rescuing someone from drowning in the ocean, you're more likely to just add the flight crew to the tally of the dead if you persist in trying to make the bird work while in an &lt;strong&gt;adverse configuration&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This does not answer what an actual pilot of that type - which I am not - would experience in flight.  But the stabilator is considered a &lt;strong&gt;flight control surface&lt;/strong&gt;, and you never take to the air without your flight controls 100% operational.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But ending up missing part of your flight control surfaces during flight would be considered an emergency condition.  If instead the aircraft is already on the ground, in need of maintenance, and one is considering a &quot;&lt;strong&gt;ferry flight&lt;/strong&gt;&quot; to somewhere else to better service it, there are many things that an inspector could let slide for just a ferry flight, but this is &lt;em&gt;not&lt;/em&gt; one of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such a stabilator contributes to the control, stability, and balance of the aircraft, and without the entire stabilator, the aircraft is not in flight configuration, and therefore, it's not &quot;&lt;strong&gt;airworthy&lt;/strong&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Definition of Airworthiness:&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;The aircraft conforms to its type design and is in a condition for safe operation.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=ce9268530ce70d33431c343ac1cdfc54&amp;amp;mc=true&amp;amp;node=se14.1.3_15&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR Part 3.5(a)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if a cogent argument is &lt;em&gt;somehow&lt;/em&gt; made that the helicopter is &quot;&lt;em&gt;in a condition for safe operation&lt;/em&gt;&quot; while lacking all or part of its stabilator, it still utterly fails the first half, being: &quot;&lt;em&gt;conforms to its type design&lt;/em&gt;&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A note regarding balance: &lt;br/&gt; &#xA;Many mid-sized helicopters have an acceptable &lt;strong&gt;CG&lt;/strong&gt; (Center of Gravity) range that's about the size and shape of a large mobile phone (as I write this in early 2016).  This is a larger craft, flown by the military, so its CG envelope may be the size of a small to medium tablet device.  Loading various people near the CG location doesn't shift the CG very much, which is why the main passenger/cargo area is always under the main rotor.  But that stabilator flight control surface could weigh 20, 50, 100 pounds or more, and removing that from the end of a long lever arm at the end of the &lt;strong&gt;tail boom&lt;/strong&gt; will cause a noticeable shift in CG location, possibly putting it out of range for the aircraft.  This is also a situation that a skilled pilot in an emergency may be able to compensate for if action is taken immediately, but is a condition you &lt;strong&gt;never&lt;/strong&gt; enter into knowingly. That way lies only heartache and doom.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am an FAA certified &lt;strong&gt;A&amp;amp;P&lt;/strong&gt; (Airframe and Powerplant) mechanic, and during my training school, the third-ranking member in the entire FAA (in 2007) came and gave a talk on a few different topics, but primarily on the concept of airworthiness.  It comes down to this:  Are you &lt;strong&gt;&lt;em&gt;SURE&lt;/em&gt;&lt;/strong&gt; it will fly safely?  &lt;em&gt;How&lt;/em&gt; sure?  Would you put &lt;em&gt;your kids&lt;/em&gt; in that aircraft and let it fly?  As aircraft mechanics, we need to be &lt;strong&gt;&lt;em&gt;that&lt;/em&gt;&lt;/strong&gt; sure that the aircraft is safe to fly, or, it simply isn't. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;An aircraft is fully airworthy, or it's not airworthy.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The Sikorsky SH-60 Seahawk, without a complete stabilator, is &lt;strong&gt;not&lt;/strong&gt; airworthy.&lt;/p&gt;&#xA;" OwnerUserId="14575" LastActivityDate="2016-04-23T05:51:34.733" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27119" PostTypeId="2" ParentId="27112" CreationDate="2016-04-23T13:43:07.917" Score="8" Body="&lt;p&gt;The short answer is that you need to get an &lt;a href=&quot;http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.3,Ch3,Sec1&quot; rel=&quot;noreferrer&quot;&gt;FAA waiver&lt;/a&gt; (special permission), as required by &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1311&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 91.311&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;§91.311   Towing: Other than under §91.309.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;No pilot of a civil&#xA;aircraft may tow anything with that aircraft (other than under&#xA;§91.309) except in accordance with the terms of a certificate of&#xA;waiver issued by the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1309&quot; rel=&quot;noreferrer&quot;&gt;91.309&lt;/a&gt; is about towing gliders, so banner towing comes under 91.311.)&lt;/p&gt;&#xA;&lt;p&gt;You need at least a private pilot certificate to tow banners - sport and recreational pilots aren't allowed to do it - but since most banner towing is paid work, in practice the pilot will usually have a commercial certificate (this is from the waiver instructions):&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;When banner tow operations are conducted for compensation or hire, the&#xA;pilot must have at least a limited commercial pilot certificate&#xA;(without an instrument rating) and at least a valid second class&#xA;medical certificate. An instrument rating is not a requirement for&#xA;this operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The FAA has a &lt;a href=&quot;http://fsims.faa.gov/wdocs/other/faa-fs-i-8700-1_rev1.pdf&quot; rel=&quot;noreferrer&quot;&gt;complete guide on banner towing&lt;/a&gt; and the waiver issue process has more administrative details. There don't seem to be many specific airspace requirements apart from the obvious, e.g. no towing in a TFR zone. But the FAA can impose more or less any conditions that they like as part of a waiver, and it will include the approved times and areas for operation.&lt;/p&gt;&#xA;&lt;p&gt;(As an aside, it's widely believed in the pilot community that the permanent &lt;a href=&quot;http://tfr.faa.gov/save_pages/detail_4_3621.html&quot; rel=&quot;noreferrer&quot;&gt;stadium&lt;/a&gt; and &lt;a href=&quot;http://tfr.faa.gov/save_pages/detail_4_3634.html&quot; rel=&quot;noreferrer&quot;&gt;Disney&lt;/a&gt; TFRs are really there to prevent banner towing, not to increase security.)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-09-24T03:25:12.180" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27120" PostTypeId="2" ParentId="27114" CreationDate="2016-04-23T15:10:29.863" Score="25" Body="&lt;p&gt;What Mike said is correct, but I thought I'd add a little more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The hose is technically called the &quot;PCA Hose&quot; which stands for Pre-Conditioned Air Hose. The hose supplies pre-conditioned air to the aircraft from a ground based unit, that is typically electrically powered and is usually mounted on to each jetbridge. The air can be cold or hot, depending on the needs of the day. The aircraft has a connection that feeds directly into the aircraft's air distribution mix manifold, which is where recirculating air is mixed with fresh pack air before being sent back to the cabin. The ground port connector port has an exterior door and an internal check valve to prevent pressured air from escaping in flight (the 757 actually has two internal check valves that are in series). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the pre-conditioned air is connected to the aircraft, a small amount of it is sent directly to the cockpit and is 100% fresh (at least on Boeing aircraft), while the remaining PCA air is sent to the mix manifold where it mixed with recirculated cabin air before being released into the cabin. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main reason to use pre-conditioned air is that it allows the crew to shut off the APU (and air conditioning packs) at the gate, which reduces fuel burn, emissions, noise and maintenance cost. When fuel costs went up dramatically in the mid '00s, there was a major push at airlines to eliminate APU run times, because it is much cheaper to run a ground based, electric air conditioner than running the mini-jet engine to produce bleed air. At the same time, there was also a push to ensure that aircraft were connected to ground electrical power as well, for the same reason. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are some downsides of using PCA air. First, the hoses get a ton of debris in them and the hoses themselves breakdown internally. All of this debris gets blown back into the aircraft and clogs up the ducts and gaspers. This drives a lot of extra maintenance cost on the air distribution system, which didn't used to require much maintenance. Screens help some, but don't fully fix the problem. Second, ground crew tend to always use the max flow setting on the ground unit, and this can over pressurize ducts on narrowbody aircraft, leading to their failure (especially when the ducts are clogged). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Third, many crews/airports think that on a &quot;hot day&quot; you still have to run the APU, this is false and actually counter productive the cold ground air blows directly on the mix manifold's temperature sensor, so the airplane thinks the air is too cold and starts adding &quot;trim air&quot; from the APU to heat up the mixed air. So running the APU actually makes the cabin hotter, but then the ground crew thinks &quot;since the aircraft is hot with the ground air and APU, imagine how hot it'd be with just the ground air!&quot; I've seen this a lot more at airports where 85F is considered a hot day, as opposed to airports where 105F is considered hot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, there is a lot of infrastructure and maintenance that goes into all the ground equipment and at some airports, the ground units are actually diesel powered. So at the end of the day, using PCA air and ground power probably save some money, but it definitely isn't &quot;free.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: As to the reason the PCA hose pictured is coming from the ramp instead of the jetbridge, this has to with the infrastructure setup at each airport. There are many systems that can route the PCA air underground. I assume that most of these systems use a centralized plant loop with chilled water/steam pumped throughout the terminal, then use a heat exchanger at each gate. Take a look at the recent setup at SEA for more information: &lt;a href=&quot;http://www.portseattle.org/Business/Construction-Projects/Airport-Projects/Pages/Pre-Conditioned-Air.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;SEA PCA Centralization Project&lt;/a&gt;. This Cavotec brochure has some interesting information and graphics as well: &lt;a href=&quot;https://web.archive.org/web/20160716062015/http://www.cavotec.com/static/upload/media/Market_Brochure_Airports.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cavotec Brochure (PDF)&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="36340" LastEditDate="2019-10-03T20:38:20.953" LastActivityDate="2019-10-03T20:38:20.953" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27122" PostTypeId="2" ParentId="27099" CreationDate="2016-04-23T19:52:46.637" Score="7" Body="&lt;p&gt;Let us state the known facts (from the question and its comments):&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The altitude reported on the passenger entertainment system was observed to be 42,000 feet.&lt;/li&gt;&#xA;&lt;li&gt;The aircraft was an Airbus A320.&lt;/li&gt;&#xA;&lt;li&gt;Looking up the flight history shows the plane flown at 36,000 feet.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;h2&gt;Case #1: aircraft was flying at FL420&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;As noted in the comments, this is beyond the certified service ceiling of the A320. Also, this would contradict (3), which data is collected via ADS-B and presumably correct.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Case #2: the OP misread &quot;latitude&quot; as &quot;altitude&quot;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;From my experience flying as a passenger, the raw longitude and latitude data is not displayed on the passenger's flight information screen. There would be no need to, since (most) passengers would not carry a map with them and plot the coordinates onto it. The coordinates themselves are therefore useless information, and I doubt the engineers who designed the software of the entertainment system would put it in.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Case #3: reported altitude was geometric height&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;I don't have a source for this, but I don't think the passenger's entertainment system would have a function to convert pressure altitude into geometric height, when even the pilots don't have it.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Case #4: the reported altitude does not correspond to the altimeter's reading&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The flight information display reports data captured in the cockpit in real time. Data such as the plane's location, speed, altitude, vertical speed, heading and winds aloft, are supplied by the flight management computer and are identical to those seen by pilots. I know this is the case as I always watch the flight information screen closely during takeoffs and landings, and the readings correspond to how a pilot would have flown a SID or STAR. &lt;em&gt;(I always fear the pilots may mess up and I would feel safer if I'm in the cockpit, but since I'm not allowed to do that, I watch the flight information screen to act as &quot;passenger monitoring&quot;.)&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;I'm left with one conclusion:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The altimeter's reading was wrong&lt;/strong&gt;. There are multiple altimeters on an airplane like this. If one of them malfunctions, the pilots can set the source of the autopilot and flight management computer to another good altimeter. But since the passenger's flight information display is a non-critical system, its source probably cannot be switched, hence the wrong data is displayed in the cabin (most passengers don't know what are the nominal values anyway).&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-04-23T19:52:46.637" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27123" PostTypeId="1" CreationDate="2016-04-23T20:30:49.177" Score="0" ViewCount="144" Body="&lt;p&gt;Are there any innovations that were made during the development or flight of &lt;a href=&quot;http://www.solarimpulse.com/&quot; rel=&quot;nofollow&quot;&gt;the Solar Impulse plane&lt;/a&gt; that would go into any type of regularly used airplanes in the near future?&lt;/p&gt;&#xA;" OwnerUserId="14627" LastEditorUserId="62" LastEditDate="2016-04-23T21:05:10.967" LastActivityDate="2016-04-23T21:46:57.620" Title="Is there any benefit to science from the Swiss built solar plane flying across the globe?" Tags="&lt;aircraft-design&gt;&lt;electric-engine&gt;&lt;solar-impulse&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ClosedDate="2016-04-24T06:51:24.523" ContentLicense="CC BY-SA 3.0" />
  <row Id="27124" PostTypeId="2" ParentId="25765" CreationDate="2016-04-23T20:38:14.280" Score="3" Body="&lt;p&gt;After a lot of Googling, it looks to me like a side-step ILS approach is exclusively a US term and - at least practically speaking - it doesn't exist in the rest of the world. There are almost no relevant search hits for the term in other countries; Transport Canada &lt;a href=&quot;https://www.tc.gc.ca/eng/civilaviation/opssvs/secretariat-terminology-glossary-825.htm&quot; rel=&quot;nofollow&quot;&gt;includes it in their glossary&lt;/a&gt; but it's a direct copy from the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA's P/CG&lt;/a&gt; and is noted as a US term:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;U.S.: A visual maneuver [sic] accomplished by a pilot at the&#xA;  completion of an instrument approach to permit a straight-in landing&#xA;  on a parallel runway not more than 1200 ft to either side of the&#xA;  runway to which the instrument approach was conducted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I did find out that some other countries use the term &lt;em&gt;swingover&lt;/em&gt; for more or less the same thing, but the only two extensive sources I found are in German: &lt;a href=&quot;https://www.ivao.de/kompendium/Swingover&quot; rel=&quot;nofollow&quot;&gt;IVAO Deutschland&lt;/a&gt; and &lt;a href=&quot;https://de.wikipedia.org/wiki/Swing_Over&quot; rel=&quot;nofollow&quot;&gt;wikipedia.de&lt;/a&gt;. Neither of them quotes a regulatory or ICAO source. The IVAO page says that pilots usually ask for a swingover, whereas in the US - at least based on what I found in forums - ATC will request it from the pilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even if you're willing to accept that &quot;it's a US thing&quot;, it doesn't explain &lt;em&gt;why&lt;/em&gt; only the US has side-step approaches. I can think of a fairly vague reason, but I may be completely wrong. Side-step minima are different, as the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;ATC orders&lt;/a&gt; (section 4-8-7) note:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Side-step maneuvers require higher weather minima/MDA. These higher&#xA;  minima/MDA are published on the instrument approach charts&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means it takes actual work to create side-step minima, you can't just use them 'for free' from another ILS approach. So my guess here is that the US simply has - or, historically, had - better ILS and weather reporting facilities than many other countries do, as well as more resources directed at defining approaches and &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_the_world%27s_busiest_airports_by_passenger_traffic&quot; rel=&quot;nofollow&quot;&gt;more flights going into busy airports&lt;/a&gt;. In other words, side-step approaches are more practical, 'affordable' and useful for the US than for other countries. But that's entirely my own speculation, and if someone can find a documented reason that would be great.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-04-23T20:47:02.973" LastActivityDate="2016-04-23T20:47:02.973" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27125" PostTypeId="2" ParentId="23074" CreationDate="2016-04-23T20:46:12.567" Score="2" Body="&lt;p&gt;I know nothing about PDCs, but it does seem that they are now standardized. One aircrew training site &lt;a href=&quot;https://www.aircrewacademy.com/follow-the-agonic-line/313-finally-pdc&quot; rel=&quot;nofollow&quot;&gt;said in April 2014&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For those of you capable of receiving a Predeparture Clearance (PDC),&#xA;  have you noticed a change since the first week of April? The FAA&#xA;  changed the way it issues PDCs. Gone are the days of trying to decide&#xA;  if you got a reroute in the PDC. The FAA recognized there was a&#xA;  problem with standardization with regards to reroutes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The article points to &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/2015-04-13_JO_7110_113E_Final.pdf&quot; rel=&quot;nofollow&quot;&gt;JO 7110.113&lt;/a&gt;, &lt;em&gt;Procedures for Issuing Automated Clearances&lt;/em&gt;, which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5. Explanation of Policy Changes.&lt;/strong&gt; This order is revised to provide standardization of PDC clearances across the FAA.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess you can read the rest of the JO for more information, it means nothing to me :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-04-23T20:46:12.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27127" PostTypeId="1" AcceptedAnswerId="27193" CreationDate="2016-04-23T21:34:03.437" Score="7" ViewCount="981" Body="&lt;p&gt;At what point is a pilot considered to have accepted an clearance or instruction? Upon simple acknowledgement (&lt;em&gt;e.g.&lt;/em&gt;, &lt;code&gt;Roger&lt;/code&gt; or &lt;code&gt;Wilco&lt;/code&gt;), any readback, &lt;em&gt;correct&lt;/em&gt; readback, or something else?&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="14661" LastEditDate="2016-06-08T16:16:22.517" LastActivityDate="2016-06-08T16:19:34.623" Title="When has a pilot legally accepted an ATC clearance or instruction?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;clearance&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27128" PostTypeId="2" ParentId="27123" CreationDate="2016-04-23T21:46:57.620" Score="2" Body="&lt;p&gt;As you can see from the massive delay in its flight schedule, the Solar Impulse II has run &lt;a href=&quot;http://www.theguardian.com/environment/2015/jul/15/solar-plane-impulse-2-suspends-flight-hawaii&quot; rel=&quot;nofollow&quot;&gt;into some problems&lt;/a&gt;. This is always an indication that something has been learned. Unfortunately, what has been learned is that electric flight is even harder than expected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The value of this particular airplane is the demonstration that purely electric long-range flights are possible, and in this it ranks with the &lt;a href=&quot;http://www.weebau.com/history/opel-rak.htm&quot; rel=&quot;nofollow&quot;&gt;first rocket-powered airplanes in 1928 and 1929&lt;/a&gt; - yes, it can be done, but for now there is no practical value in it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for long term developments - this is just speculation, but I doubt that in 50 or 100 years we will see the Solar Impulse II as the starting point of a new era.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-04-23T21:46:57.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27129" PostTypeId="2" ParentId="12303" CreationDate="2016-04-23T23:34:24.377" Score="9" Body="&lt;p&gt;I can relate to you the true story of my uncle who successfully landed a large WWII aircraft with no flight training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He was the flight surgeon on board a large aircraft that got heavily shot up.  Hostile fire killed or severely injured every crew member.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He moved the pilot out of his seat, and contacted a control tower.  With the expert help of the control tower operators, he successfully landed the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After the war, he had a private practice in his home where he saw patients.  For patients too ill to come to him, he performed house calls.  He continued to perform house calls until a short time before he passed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have always thought his life story would form a compelling foundation for an inspiring movie.&lt;/p&gt;&#xA;" OwnerUserId="4095" LastActivityDate="2016-04-23T23:34:24.377" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27130" PostTypeId="2" ParentId="27099" CreationDate="2016-04-24T00:23:11.337" Score="4" Body="&lt;p&gt;Nobody ever flies at FL420, ever. RVSM airspace, where usable altitudes are 1000' (10 FL's) apart, stops at FL410. Above that, only &quot;odd&quot; altitudes are used: FL430, FL450, FL470. Between the lower service ceiling &amp;amp; the unusability of FL420, I'd totally agree that the &lt;em&gt;entertainment system's&lt;/em&gt; altitude readout was wrong. What causes this, however, is a harder question; if the aircraft altimetry systems were messed up, getting an ATC clearance &lt;em&gt;into&lt;/em&gt; RVSM airspace (above FL280) could be problematic at best.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd wonder if the entertainment system wasn't jumbling things around somehow &amp;amp; putting bad data on the displays. And then that glitch was fixed in the &quot;return home&quot; airplane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Side note - @JanHudec makes 2 excellent point in comments on the other answer about the possibility of the IFE using GPS altitude. Other then the magnitude of the 6000' delta between the flown altitude and the reported altitude, I could readily believe that the IFE might be reporting GPS altitude rather than the more accurate info from the FMS.)&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-04-24T00:31:09.843" LastActivityDate="2016-04-24T00:31:09.843" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27131" PostTypeId="1" AcceptedAnswerId="27132" CreationDate="2016-04-24T01:54:42.707" Score="5" ViewCount="1979" Body="&lt;p&gt;How do fighter jet flares work?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the concept behind them and how do they stop impending missiles during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And also how do pilots know when a good time to launch flares is?&lt;/p&gt;&#xA;" OwnerUserId="14628" LastEditorUserId="1467" LastEditDate="2017-04-07T11:01:18.593" LastActivityDate="2017-04-09T13:11:05.403" Title="How do flares work?" Tags="&lt;fighter&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27132" PostTypeId="2" ParentId="27131" CreationDate="2016-04-24T02:12:47.930" Score="7" Body="&lt;p&gt;You have 3 questions here (Or maybe 2 because the first and second are very similar)&lt;/p&gt;&#xA;&lt;h1&gt;1 and 2:&lt;/h1&gt;&#xA;&lt;p&gt;Flares are some sort of burning compound that generates a significant amount of heat to distract (hopefully) an Infra-Red guided missile. They attract the IR missiles because the amount of IR energy created by them may be greater than that of the exhaust, which is what IR missiles follow.&lt;/p&gt;&#xA;&lt;h1&gt;3&lt;/h1&gt;&#xA;&lt;p&gt;The flares are deployed when the plane detects the presence of an IR missile. (&lt;a href=&quot;https://en.wikipedia.org/wiki/Flare_%28countermeasure%29#Tactics&quot; rel=&quot;noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Once the presence of a &amp;quot;live&amp;quot; IR missile is indicated, flares are released by the aircraft in an attempt to decoy the missile; some systems are automatic, while others require manual jettisoning of the flares.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;They also &lt;a href=&quot;https://www.google.com/search?q=military%20airplane%20flares%20at%20airshow&amp;amp;biw=1021&amp;amp;bih=635&amp;amp;tbm=isch&amp;amp;tbo=u&amp;amp;source=univ&amp;amp;sa=X&amp;amp;ved=0ahUKEwirmPqxmabMAhXMwYMKHbW3ADYQsAQIGw#imgrc=_&quot; rel=&quot;noreferrer&quot;&gt;deploy them for show&lt;/a&gt; too.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-04-07T17:12:02.287" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27133" PostTypeId="2" ParentId="12303" CreationDate="2016-04-24T03:47:41.357" Score="8" Body="&lt;p&gt;&lt;strong&gt;Yes.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The question will have subjective answers and this is my opinion.  The basics of flying an airplane doesn't change from a single engine airplane to a big airliner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The concept of lining up on final, flaring into the touchdown attitude and setting it down is exactly the same.  There are some things that are different; for example, retractible landing gear, leading edge slats, spoilers and thrust reversers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of the differences can be overcome by talking with ATC and an instructor / pilot trained to fly that airplane through the radio.  The biggest challenge would be knowing when to flare as you are sitting much higher in an airliner than in a single engine airplane.  This can be overcome with listening to the radar altimeter and flaring as directed by the instructor.  &lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-04-24T03:47:41.357" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27134" PostTypeId="1" CreationDate="2016-04-24T04:12:10.733" Score="4" ViewCount="1812" Body="&lt;p&gt;I was at KORD this week for the first time in decades. I spotted 4 control towers (two near the terminals, and one at each end—and I am not sure if I got them all). I was not counting the short ones, obviously for gate control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the division of labor?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it anything like KDFW?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/O3G4f.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/O3G4f.jpg&quot; alt=&quot;#1&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/MdWOF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MdWOF.jpg&quot; alt=&quot;#2&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ZwgMX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZwgMX.jpg&quot; alt=&quot;#3&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/XacrQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XacrQ.jpg&quot; alt=&quot;#4&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was not counting&#xA;&lt;a href=&quot;https://i.stack.imgur.com/YvWg4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YvWg4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/E342f.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/E342f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2129" LastEditorUserId="19" LastEditDate="2016-10-14T13:41:28.153" LastActivityDate="2017-02-22T18:49:54.147" Title="What is the division of tasks among the control towers at Chicago O'Hare airport?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27135" PostTypeId="1" AcceptedAnswerId="27137" CreationDate="2016-04-24T05:19:02.737" Score="1" ViewCount="319" Body="&lt;p&gt;I've had my IFR rating for ~2 years now, but haven't done much other than practice approaches to stay current. Flying to KBKL tomorrow, and when I depart to come back, I can't tell who I call to pick up my clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approach plates say &quot;CLNC DEL 121.9 (when tower closed)&quot; - okay, what about when the tower is open?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've tried googling around, but the internet is filled with people asking how to pick up clearances in the air; I trained at a non-towered field so I've got the opposite issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Here's a link: &lt;a href=&quot;http://airnav.com/airport/KBKL&quot; rel=&quot;nofollow&quot;&gt;http://airnav.com/airport/KBKL&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="204" LastActivityDate="2016-04-24T10:03:09.193" Title="Who do I call to pick up my IFR Clearance at KBKL?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27136" PostTypeId="1" AcceptedAnswerId="27139" CreationDate="2016-04-24T08:06:14.570" Score="4" ViewCount="404" Body="&lt;p&gt;I read this news:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://edition.cnn.com/2016/04/23/us/boeing-dreamliner-engine-fix/index.html&quot; rel=&quot;nofollow&quot;&gt;http://edition.cnn.com/2016/04/23/us/boeing-dreamliner-engine-fix/index.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So seemingly the reliability of the 787 engines made by General Electric is not as high as expected and need to be overhauled to increase reliability. If one engine fails due to icing there should be also increased chances that the second one may fail as well.&#xA;Does it mean that - even temporarily - this may have an effect on the plane's ETOPS rating?&lt;/p&gt;&#xA;" OwnerUserId="14065" LastEditorUserId="1467" LastEditDate="2016-04-24T08:23:43.983" LastActivityDate="2016-04-24T12:02:42.083" Title="Can the need for an engine overhaul affect the ETOPS rating?" Tags="&lt;boeing-787&gt;&lt;etops&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27137" PostTypeId="2" ParentId="27135" CreationDate="2016-04-24T10:03:09.193" Score="6" Body="&lt;p&gt;When there is no separate Clearance Delivery frequency, just call on the ground control frequency to get your clearance.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Separate Clearance Delivery frequencies are only needed at busy airports to relieve radio congestion and work load. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even at a &quot;busy&quot; airport sometimes you will see(hear) one controller work both Ground and Clnc Del when the workload is low. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-04-24T10:03:09.193" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27138" PostTypeId="1" AcceptedAnswerId="27163" CreationDate="2016-04-24T11:35:04.960" Score="0" ViewCount="289" Body="&lt;p&gt;I know that they repair everything that concerns engines, but what is the actual day for them. Do they sit in the factories or work in airports?&lt;/p&gt;&#xA;" OwnerUserId="14630" LastEditorUserId="1467" LastEditDate="2016-04-24T15:22:23.100" LastActivityDate="2016-04-25T20:19:45.793" Title="What does a jet engine technician do?" Tags="&lt;jet-engine&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-04-30T14:34:52.000" ContentLicense="CC BY-SA 3.0" />
  <row Id="27139" PostTypeId="2" ParentId="27136" CreationDate="2016-04-24T12:00:50.800" Score="6" Body="&lt;p&gt;Every time an engine is shut down in flight, it is tracked. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engine reliability does affect ETOPS certification. In addition to the aircraft being certified, each airline is also ETOPS certified. An aircraft or an airline with a poor record could have its ETOPS certification downgraded, or even potentially revoked. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/ETOPS&quot;&gt;Wikipedia ETOPS Approval&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;ETOPS approval is a two-step process. First, the airframe and engine combination must satisfy the basic ETOPS requirements during its type certification. This is called &quot;ETOPS type approval&quot;. Such tests may include shutting down an engine and flying the remaining engine during the complete diversion time. Often such tests are performed in the middle of the ocean. It must be demonstrated that, during the diversion flight, the flight crew is not unduly burdened by extra workload due to the lost engine and that the probability of the remaining engine failing is extremely remote. For example, if an aircraft is rated for ETOPS-180, it means that it should be able to fly with full load and just one engine for 3 hours.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Second, an operator who conducts ETOPS flights must satisfy their own&#xA;  country's aviation regulators about their ability to conduct ETOPS&#xA;  flights. This is called &quot;ETOPS operational certification&quot; and involves&#xA;  compliance with additional special engineering and flight crew&#xA;  procedures in addition to the normal engineering and flight&#xA;  procedures. Pilots and engineering staff must be qualified and trained&#xA;  for ETOPS. An airline with extensive experience operating long&#xA;  distance flights may be awarded ETOPS operational approval&#xA;  immediately, others may need to demonstrate ability through a series&#xA;  of ETOPS proving flights.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Regulators closely watch the ETOPS performance of both type&#xA;  certificate holders and their affiliated airlines. Any technical&#xA;  incidents during an ETOPS flight must be recorded. From the data&#xA;  collected, the reliability of the particular airframe-engine&#xA;  combination is measured and statistics published. The figures must be&#xA;  within limits of type certifications. Of course, the figures required&#xA;  for ETOPS-180 will always be more stringent than ETOPS-120.&#xA;  Unsatisfactory figures would lead to a downgrade, or worse, suspension&#xA;  of ETOPS capabilities either for the type certificate holder or the&#xA;  airline.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="1467" LastEditDate="2016-04-24T12:02:42.083" LastActivityDate="2016-04-24T12:02:42.083" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27141" PostTypeId="2" ParentId="12303" CreationDate="2016-04-24T18:56:41.210" Score="5" Body="&lt;p&gt;I'd share a personal experience: a few years ago I got the chance to fly a Boeing 737 simulator (the &lt;em&gt;real&lt;/em&gt; thing, not the PC simulator!) At that time the only real aircraft I've flown was a Cessna 172. I managed to land on &lt;a href=&quot;https://en.wikipedia.org/wiki/Kai_Tak_Airport&quot; rel=&quot;nofollow&quot;&gt;Kai Tak airport&lt;/a&gt; in the simulator on my very first attempt to land a (simulated) 737. I was so nervous that I totally forgot to call for the landing checklist, and the instructor helped me with the gear and flaps, but I was the sole manipulator of the controls and I landed with no automation whatsoever, not even ILS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How? There were a few factors that came into play:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;I learnt how planes fly in ground school. Big planes fly just the same way as smaller planes, only with larger wings and more powerful engines.&lt;/li&gt;&#xA;&lt;li&gt;I knew how to manipulate the flight controls. It came as a bit of a surprise that the controls feel heavier than I'd expect, but they behaved the same anyway.&lt;/li&gt;&#xA;&lt;li&gt;My enthusiasm in aviation meant I have learnt beyond the Cessna 172 from books, online articles and PC simulation experience. I was not able to identify every single switch and knob in the cockpit, but I knew enough to fly the plane in that situation.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;My answer? If it's a perfectly flyable aircraft (no failures), calm weather, then &lt;strong&gt;Yes, definitely!&lt;/strong&gt; Here's what I'd do if it happens in real life:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;Aviate, navigate, communicate.&lt;/strong&gt; No matter what happens, always remember that. That means the first thing to do after entering the cockpit is not to find the radio buttons and call for help; the first thing is to access all primary flight instruments and make sure we're flying.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Radio for help&lt;/strong&gt;. Declare an emergency on the last radio frequency. If no one responds, tune to 121.5 and try again.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Request a long runway with calm weather.&lt;/strong&gt; Unless it's something like a A380 or Boeing 747, chances are there would be a runway long enough so you don't have to worry about hitting the touchdown spot.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Setup autoland&lt;/strong&gt;, if available. Autoland requires suitable equipment both on the plane and on the ground. If it's not available, given a long enough final (say 20 miles), I think I'd feel comfortable hand flying the aircraft down.&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;Have the emergency trucks standing by&lt;/strong&gt;. In the event I crashed during landing, gear collapsed or whatever, everyone'd be ready to help.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-04-27T08:34:31.997" LastActivityDate="2016-04-27T08:34:31.997" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27142" PostTypeId="2" ParentId="12303" CreationDate="2016-04-24T19:16:28.963" Score="3" Body="&lt;p&gt;Like anything in aviation, it depends, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There, to date, have been no documented cases of this happening. There have been a few &lt;a href=&quot;https://en.wikipedia.org/wiki/Talk_down_aircraft_landing&quot; rel=&quot;nofollow&quot;&gt;&quot;talk down landings&quot;&lt;/a&gt; in smaller aircraft with low time or inexperienced pilots. Similarly there is at least &lt;a href=&quot;https://www.youtube.com/watch?v=sOO_oYZF_B0&quot; rel=&quot;nofollow&quot;&gt;one documented case&lt;/a&gt; of an air force &lt;a href=&quot;https://en.wikipedia.org/wiki/Rockwell_B-1_Lancer&quot; rel=&quot;nofollow&quot;&gt;B-1B&lt;/a&gt; Pilot assisting in &lt;a href=&quot;http://www.mirror.co.uk/news/world-news/off-duty-pilot-lands-plane-saves-3640802&quot; rel=&quot;nofollow&quot;&gt;landing an airliner&lt;/a&gt; he had no experience flying but you can argue he had plenty of jet time. People have &lt;a href=&quot;https://www.youtube.com/watch?v=htg0VKt3j_w&quot; rel=&quot;nofollow&quot;&gt;tried it in simulators of course&lt;/a&gt; but a sim is a sim. Of course things like cross winds and runway length will play into the success rate of an event like this. I will say that the margin of error on these things is small and on a calm day I'm sure it's possible. I would hesitate to give a hard yes to this question since there are far to many factors to take into account but I do feel under the correct circumstances it could be done. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a small side note, since this question is about Quad Engine planes (747, A380 etc) considering the distances those planes typically fly it's more than likely that there is one if not two relief crews on the plane so the chances of everyone becoming incapacitated and requiring a passenger step up to the plate is slim to none.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-04-26T19:08:45.577" LastActivityDate="2016-04-26T19:08:45.577" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27143" PostTypeId="1" CreationDate="2016-04-24T19:59:29.263" Score="0" ViewCount="208" Body="&lt;p&gt;I am 25 years old, I have completed my bachelor  degree  from electrical  engineering. So what should I do to become a pilot?&lt;/p&gt;&#xA;" OwnerUserId="14633" LastEditorUserId="62" LastEditDate="2016-04-24T20:16:43.243" LastActivityDate="2016-04-24T21:26:55.817" Title="What should I do to become a commercial pilot?" Tags="&lt;career&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-04-24T23:10:29.710" ContentLicense="CC BY-SA 3.0" />
  <row Id="27144" PostTypeId="2" ParentId="27095" CreationDate="2016-04-24T21:03:58.403" Score="1" Body="&lt;p&gt;I find this an odd question.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I am &lt;em&gt;looking over the nose&lt;/em&gt;, my head is wings level. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But most of the time my head is moving around anyway, scanning for traffic and scanning instruments. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And especially when turning, I am looking &lt;em&gt;through&lt;/em&gt; the turn which means say 30 degrees to the side of the nose, and up and down over the horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I can't say how my head is oriented, except to say it's pointed at where I want to look. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-24T21:03:58.403" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27145" PostTypeId="2" ParentId="27143" CreationDate="2016-04-24T21:26:55.817" Score="1" Body="&lt;p&gt;If you plan to train and fly in the US...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should spend that money on an MSE or MBA, get your private/instrument, and then buy your own plane and fly whenever you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you feel you must become a commercial pilot you should find a local flight school and lay out a plan with someone who has authourity to negotiate pricing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-lay out your objective.  You are paying for a private license, instrument, all of the time building for commercial, and then commercial.  That's a minimum of 250 flight hours plus a lot of billable hours for a very lucky CFI.  You can negotiate an awesome rate if you guarantee the school that business in s short amount of time.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-DO NOT pre-pay more than $1000 at a time.  Keeping funds on account is fine, just don't give them more than you're comfortable losing if suddenly they close.  It happens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-stick to a schedule.  Fly a lot.  It's cheaper to knock it all out at once.  You have to relearn stuff if you only fly once or twice a week.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-don't get caught up comparing part 61 and part 141 schools.  Just go with the most affordable option.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-research airline minimums.  A commercial cert won't necessarily get you a job.  If fact, a commercial cert means very little wothout hours to go with it.  Think about adding a CFI cert to your shopping list.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastActivityDate="2016-04-24T21:26:55.817" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27146" PostTypeId="2" ParentId="27095" CreationDate="2016-04-25T00:03:16.350" Score="5" Body="&lt;p&gt;You need to keep your head level with reference to the airplane and not the horizon.  Until you learn this basic building block, other more advanced things will be difficult to grasp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane Flying Handbook, pg. 3-11&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The pilot’s posture while seated in the airplane is very important, particularly during turns. It will affect the interpretation of outside visual references. At the beginning, the student may lean away from the turn in an attempt to remain upright in relation to the ground rather than ride with the airplane. This should be corrected immediately if the student is to properly learn to use visual references. [Figure 3-12]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/EbVmt.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EbVmt.png&quot; alt=&quot;Figure 3-12&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="14613" LastEditDate="2016-05-11T20:32:59.163" LastActivityDate="2016-05-11T20:32:59.163" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27147" PostTypeId="2" ParentId="1287" CreationDate="2016-04-25T01:27:03.410" Score="2" Body="&lt;p&gt;The biggest problem you face in a propeller aircraft when going through a flock of birds is instant IFR. You don't want to do that on landing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had the experience of a flock of Canadian geese taking off as I was committed to takeoff while soloing as a student pilot. It was a spectacular mess, right out of a Friday the 13th Movie (or Indiana Jones).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I had to fly by instruments to climb to a safe altitude then maintain straight and level. Then I had to search the plane for some spare paper towels that I used to create a clear area in the windscreen so that I could see to land (reaching out the side window).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, it is best to stay away from the birds. If they take off, you can abort the landing and climb. If the runway is long enough, you can land long, past the birds.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-04-25T01:27:03.410" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27148" PostTypeId="1" CreationDate="2016-04-25T08:26:22.180" Score="4" ViewCount="133" Body="&lt;p&gt;when the aircraft navigation system is tuned to VHF COM frequency (118-137.990MHz) then COM receiver will able to receive two types of signals one is COM signal and the other is AUX COM signal what is the difference between them ?&lt;/p&gt;&#xA;" OwnerUserId="12307" LastActivityDate="2016-04-26T19:13:50.667" Title="What is the difference between COM and Auxilary COM signals?" Tags="&lt;radio-communications&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27149" PostTypeId="1" AcceptedAnswerId="27150" CreationDate="2016-04-25T08:48:41.360" Score="0" ViewCount="838" Body="&lt;p&gt;Why do we always use circular nozzles for commercial aircraft engines? Other shapes like rectangular nozzles are used in military aircraft, e.g., &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor&quot; rel=&quot;nofollow&quot;&gt;Raptor&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_F-117_Nighthawk&quot; rel=&quot;nofollow&quot;&gt;Nighthawk&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="14522" LastEditorUserId="1696" LastEditDate="2016-07-05T19:34:59.133" LastActivityDate="2016-07-05T19:34:59.133" Title="Why do we always use circular nozzles for commercial aircraft engines?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;engine-design&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-04-25T10:47:21.963" ContentLicense="CC BY-SA 3.0" />
  <row Id="27150" PostTypeId="2" ParentId="27149" CreationDate="2016-04-25T09:55:57.393" Score="3" Body="&lt;p&gt;Simple geometry: Circles are strong, and provide a large area for the amount of material used. That means you get more intake/nozzle for the cost of the materials, while giving you a strong and (relatively) light engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A circle also helps to keep the airflow smooth, because it's (again, relatively) uniform: no weird edges, corners, or angled things to cause turbulence, vortices, or otherwise disturb or make the airflow &quot;complicated&quot;. This is ideal at subsonic speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, this makes a circular engine the most efficient, and when it comes to commercial aircraft efficiency is king: the lighter and simpler you can make a safe engine, the better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some aircraft we will see &quot;off-circle&quot; (eg 737 engines, which have a not-quite-circular intake) or oval intake, but they're basically just circles where the dimensions have been adjusted to take a slight efficiency hit for the purpose of fitting the shape of the aircraft better.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military aircraft which use rectangular air intakes tend to do so for two different reasons, rather than because it's actually any more efficient.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Stealth. Circles scatter radar waves in a &quot;bad&quot; way for stealth. Angles are much better for stealthy aircraft&lt;/li&gt;&#xA;&lt;li&gt;Because that air intake is actually an &lt;a href=&quot;https://en.wikipedia.org/wiki/Intake_ramp&quot; rel=&quot;nofollow&quot;&gt;Intake Ramp&lt;/a&gt; designed to slow the airflow into the engine by deliberately creating a shockwave to slow the air down. This is because jet engines need subsonic air to work properly: this is why you tend to see square intakes on &lt;strong&gt;supersonic&lt;/strong&gt; aircraft. Commercial aircraft don't usually fly supersonic, though, with the notable exceptions of Concorde and the Tu-144 which both had square intakes for this reasons.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If you don't care about subsonic efficiency (Concorde/Tu-144, which were both designed to spend most of their working lives supersonic), or if you just want to be able to go supersonic at all, a square intake can make sense - but for those of us living life under Mach 1, and for airlines who care about fuel efficiency above pretty much anything else, a circle is best.&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2016-04-25T09:55:57.393" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27151" PostTypeId="1" AcceptedAnswerId="27152" CreationDate="2016-04-25T10:32:52.910" Score="15" ViewCount="3226" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-144&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tupolev TU-144&lt;/a&gt; uses retractable canards to stabilize the aircraft while starting and landing. On this picture you can see them very well:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ncO64.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ncO64.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;http://www.airlinefan.com/airline-photos/large/1800968/Aeroflot/Tupolev/Tu-144/CCCP-77110/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirlineFan.com&lt;/a&gt; Copyright: VOLPATI&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It doesn't have reverse thrust and air-brakes, and relies purely on very strong wheel brakes. Wouldn't it be possible to rotate the canards by 90° (after touchdown) in order to create a very large air-brake? I don't think it would need too many modifications to the current form of the canards.&lt;/p&gt;&#xA;" OwnerUserId="14457" LastEditorUserId="22726" LastEditDate="2019-01-24T03:45:32.047" LastActivityDate="2019-01-24T03:45:32.047" Title="Why aren't the canards used as airbrakes on the Tupolev Tu-144?" Tags="&lt;supersonic&gt;&lt;braking&gt;&lt;canard&gt;&lt;tu-144&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27152" PostTypeId="2" ParentId="27151" CreationDate="2016-04-25T11:20:33.220" Score="30" Body="&lt;p&gt;A number of things happen when you rotate the canards by 90°, and in no way I see how these could be addressed by &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;not too many modifications&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h1&gt;1. Transient&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Once you land, you need a certain amount of time to rotate the canards. During this time the canards will not produce a perfectly horizontal force, but it will have also a vertical component.&#xA;Whether this component will be upwards or downwards it will depend on the rotation direction: rotate them with the leading edge up, and you will have some upward force; downward otherwise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both cases this is not ideal:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;an upward force will reduce the adherence of the nose wheel, reducing the steering authority&lt;/li&gt;&#xA;&lt;li&gt;a downward force will increase the load on the wheel, increasing the chance of tire burst and increasing the required size of the strut to sustain said load.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;2. Deployed Status&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Let's assume for a second that the transient problem can be avoided. Now you have two large surfaces perpendicular to the airflow that create a massive amount of drag. And torque.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You need then to design a structure that is capable of:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;keep the canard in place during the flight&lt;/li&gt;&#xA;&lt;li&gt;rotate the canard by 90°&lt;/li&gt;&#xA;&lt;li&gt;sustain the drag force during deceleration&lt;/li&gt;&#xA;&lt;li&gt;sustain the torque during deceleration&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can reduce the torque and drag forces to be transmitted through the mounting by delaying the deployment/rotation of the canards, but that would defeat the purpose or, at the very least, severely limit the usefulness of such a system.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;In conclusion, a structure that would fulfill all the listed requirements is &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;extremely likely to be heavier than equivalent brakes, &lt;/li&gt;&#xA;&lt;li&gt;more likely to be prone to structural problems due to complexity,&lt;/li&gt;&#xA;&lt;li&gt;more expensive due to maintenance,&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;making even less sense in an aviation application.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-04-25T11:47:31.803" LastActivityDate="2016-04-25T11:47:31.803" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27153" PostTypeId="1" AcceptedAnswerId="27154" CreationDate="2016-04-25T16:24:41.040" Score="49" ViewCount="6515" Body="&lt;p&gt;This photo of the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_XB-70_Valkyrie&quot; rel=&quot;noreferrer&quot;&gt;XB-70 Valkyrie&lt;/a&gt;'s main gear shows a small wheel between the two main wheels:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zwzkn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zwzkn.jpg&quot; alt=&quot;XB-70 MLG&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Courtsey of &lt;a href=&quot;http://airpigz.com/blog/2012/1/29/day-2-airpigz-air-force-museum-meetup-1-28-12.html&quot; rel=&quot;noreferrer&quot;&gt;AirPigz.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This smaller wheel doesn't touch the ground, though I can see where it might as the side walls of the main tires compress under landing weight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AirPigz site promised an explanation, but none has been forthcoming (in the 4+ years since that was posted), and I couldn't find any information on it on Wikipedia, either. Does anyone have any information (real or speculative) on what it's for?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="62" LastEditDate="2017-05-30T17:08:28.260" LastActivityDate="2017-05-30T17:08:28.260" Title="What is the purpose of the extra wheel on the XB-70 main gear?" Tags="&lt;military&gt;&lt;landing-gear&gt;&lt;experimental-aircraft&gt;&lt;xb-70-valkyrie&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27154" PostTypeId="2" ParentId="27153" CreationDate="2016-04-25T16:42:27.677" Score="72" Body="&lt;p&gt;It is a sensing wheel that is part of the antiskid braking system. It contains an electronic sensor to measure the true groundspeed of the airplane. See &lt;a href=&quot;http://www.nasa.gov/centers/dryden/pdf/87742main_H-471.pdf&quot; rel=&quot;noreferrer&quot;&gt;NASA Technical Note D-4836, &lt;em&gt;Landing Loads and Accelerations of the XB-70-1 Airplane&lt;/em&gt; (1968)&lt;/a&gt;, bottom of page 3 of the document (page 5 on the PDF):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yBceH.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yBceH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="520" LastEditorUserId="3233" LastEditDate="2016-04-26T17:17:11.067" LastActivityDate="2016-04-26T17:17:11.067" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27155" PostTypeId="1" AcceptedAnswerId="27156" CreationDate="2016-04-25T17:49:44.253" Score="4" ViewCount="4101" Body="&lt;p&gt;What happens when a small aircraft like Cessna is flying in daytime then night hits and its now pitch black with zero visibility? How does he not run into mountains and the like?&lt;/p&gt;&#xA;" OwnerUserId="14641" LastEditorUserId="12220" LastEditDate="2016-04-25T17:54:01.993" LastActivityDate="2016-04-25T19:23:55.837" Title="How does a small aircraft like a Cessna fly at night?" Tags="&lt;instrument-flight-rules&gt;&lt;visual-flight-rules&gt;&lt;night-flying&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27156" PostTypeId="2" ParentId="27155" CreationDate="2016-04-25T18:34:16.137" Score="11" Body="&lt;p&gt;Lets attack this from a few different angles. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;then night hits and its now pitch black with zero visibility?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is plenty of visibility at night, a clear night is just as nice as a clear day. As a matter of fact when the air cools at night and clouds roll out you can some times see farther than you can during the day. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here's me on a VFR approach (Piper Warrior) in to KLNS at about 10pm one night, you can see the runways are lit up nicely and can usually be spotted from 5 - 10 miles out depending on altitude.&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WOyKQ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WOyKQ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is us earlier that night heading away from KABE (those lights are Allentown PA)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/8Ghr4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Ghr4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(photo credit to my girlfriend who was bravely sitting in the back)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you can see you can still make out the horizon and plently of land marks. While it may be different during the day you can still fly VFR at night. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;zero visibility?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Zero visibility during the day is the same as zero visibility at night and as mentioned in the comments will require you to &lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;fly IFR&lt;/a&gt; if you want to fly., &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;How does he not run into mountains and the like?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Not flying into the side of a mountain is a topic of its own. You should check out &lt;a href=&quot;https://aviation.stackexchange.com/questions/22052/what-steps-can-pilots-take-to-mitigate-the-risk-of-controlled-flight-into-terrai/22054#22054&quot;&gt;my answer here&lt;/a&gt; to that very question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a more general stand point there are lots of ways to navigate in an aircraft. &lt;a href=&quot;https://aviation.stackexchange.com/questions/19295/what-will-happen-if-satellite-navigation-fails/19301#19301&quot;&gt;Here is a solid answer&lt;/a&gt; that covers most of them. The only thing that is not really feasible in a small single pilot aircraft if you are solo is celestial navigation although it could be done.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-04-25T19:23:31.780" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27157" PostTypeId="2" ParentId="27155" CreationDate="2016-04-25T18:44:48.290" Score="1" Body="&lt;p&gt;First of all, a day does not transition into a pitch-black night instantly, but gradually. When an airplane is on an altitude of 2000-3000 feet, most of the building structures and hills etc. are not an obstacle anymore and the pilot has a much better visibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For flights initiating during daylight and going to night time, there are several things which are considered.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Planning&lt;/strong&gt;&lt;br&gt;&#xA;A pilot, most of the time, plans a flight thoroughly. It includes the final destination, duration to that destination, the route, terrain underneath, weather conditions at present and the changes expected, expected traffic and many other things.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Pilot&lt;/strong&gt;&lt;br&gt;&#xA;For pitch black darkness, pilots are specially trained and are instrument flight rated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Aircraft&lt;/strong&gt;&lt;br&gt;&#xA;The aircraft have specialized and enhanced equipment which helps the pilot to navigate during such a time. Most of the time, an IFR pilot flying an airplane for night flying has enough help through different instruments in the plane that he does not need to visually be looking outside. Hence the terms IFR vs VFR.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;Other things&lt;/strong&gt;&lt;br&gt;&#xA;Many other things are considered. You can read those on &lt;a href=&quot;http://flighttraining.aopa.org/students/crosscountry/skills/night.html&quot; rel=&quot;nofollow&quot;&gt;AOPA&lt;/a&gt; or &lt;a href=&quot;http://www.planeandpilotmag.com/article/20-things-you-may-not-know-about-night-flying/#.Vx5hTqMrJTY&quot; rel=&quot;nofollow&quot;&gt;PlaneAndPilotMag&lt;/a&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="65" LastActivityDate="2016-04-25T18:44:48.290" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27158" PostTypeId="1" CreationDate="2016-04-25T18:47:37.093" Score="4" ViewCount="3810" Body="&lt;p&gt;Apologies for multiple pictures but I thought they would depict my question more clearly than a lengthy description.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image 1: Why does the aircraft still follow the straight path even if the wind is blowing from left to right?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image 2: Why does it appear that the aircraft is sliding?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image 3: Why is there no need to apply any rudder in the presence of a cross wind?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/bxYc9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bxYc9.jpg&quot; alt=&quot;Scan from book depicting effect of wind drift, with explanation (1)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Y4N6G.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Y4N6G.png&quot; alt=&quot;Scan from book depicting effect of wind drift, with explanation (1)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/KwZAX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/KwZAX.jpg&quot; alt=&quot;Scan from book depicting effect of wind drift, with explanation (1)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="9276" LastEditDate="2016-04-26T10:31:03.413" LastActivityDate="2016-04-26T14:13:01.677" Title="Why does the airplane not 'feel' the crosswind?" Tags="&lt;wind&gt;&lt;crosswind&gt;" AnswerCount="5" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27159" PostTypeId="2" ParentId="27158" CreationDate="2016-04-25T18:55:46.060" Score="14" Body="&lt;p&gt;The main reason is that you are, in fact, flying straight through the air, and the air is moving sideways. So the plane isn't really being pushed sideways or anything, it's just flying straight through something that is moving...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a simple example, if you are flying north at 150knots (the red line below) and the wind is blowing east at 20 knots (the blue line), you are going to end up flying just every so slightly North East at about 151knots (roughly). But, to your plane, you're just traveling north at 150 knots, the wind is adding the last 1 knots.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/brErv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/brErv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bottom line is that your plane flies in a straight line through the air mass, and the air mass moves as well.  You have to add these two velocities/directions together in order to find your true velocity/direction relative to the ground.  This is normally called a &lt;a href=&quot;https://www.youtube.com/watch?v=9QiPvLHfFd0&quot; rel=&quot;noreferrer&quot;&gt;&quot;vector&quot; in the aviation&lt;/a&gt; world, and if you do a bit of study into those, I think you'll have a much easier time understanding those charts.&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-04-25T19:01:25.950" LastActivityDate="2016-04-25T19:01:25.950" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27160" PostTypeId="2" ParentId="27158" CreationDate="2016-04-25T19:11:05.173" Score="24" Body="&lt;p&gt;When dealing with crosswinds and drift, I find the easiest way to understand the concept is to imagine a fast flowing river of water. If you tried to swim straight across a fast river you will end up downstream. You don't &quot;feel&quot; the current. You just keep swimming and the current carries you.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any time you have wind it is like a river of air flowing over the earth.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Traveling through a river of air is exactly like traveling through a river of water.  You don't go where you are pointed, you go where the current carries you, plus the direction you are swimming.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="9491" LastEditDate="2016-04-26T04:37:18.807" LastActivityDate="2016-04-26T04:37:18.807" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27161" PostTypeId="2" ParentId="27155" CreationDate="2016-04-25T19:23:55.837" Score="8" Body="&lt;p&gt;First, let's get the obvious answer out of the way: the aircraft flies fine, it doesn't know it's night. It's the &lt;em&gt;pilot&lt;/em&gt; who may have issues with night flying.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's true that night flying isn't the same as day flying, and some countries require additional training or even an instrument rating for night flight, but in the US (for example) night VFR flight is allowed and night training is &lt;a href=&quot;https://aviation.stackexchange.com/q/24045/62&quot;&gt;included in basic pilot training&lt;/a&gt;. VFR at night is still visual flying, and if you can't see where you're going then you need to stay on the ground. Unless perhaps you have an instrument rating, but operating in night IMC in a single-engine, single-pilot aircraft is considered fairly risky by many pilots, especially if it's over rough terrain.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To address a couple of your specific points:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Night doesn't &quot;hit&quot;; sunset is a well-known and easily planned for event. A pilot's flight planning should never be so poor that night comes as a surprise.&lt;/li&gt;&#xA;&lt;li&gt;Night is not &quot;zero visibility&quot;. With a full moon and clear skies, you can see a very long way. And unless you're in a remote area, there are usually plenty of lights visible on the ground. On the other hand, it's certainly true that some nights are darker than others, and if you fly into a cloud at night then you will indeed lose all visibility immediately. That's why most countries require some form of instrument training for night flying, even if it's very basic.&lt;/li&gt;&#xA;&lt;li&gt;While pilots do occasionally &lt;a href=&quot;https://en.wikipedia.org/wiki/Controlled_flight_into_terrain&quot; rel=&quot;nofollow noreferrer&quot;&gt;run into mountains&lt;/a&gt;, it's also something that &lt;a href=&quot;https://aviation.stackexchange.com/q/22052/62&quot;&gt;they plan to avoid&lt;/a&gt; by choosing a good route and altitude. This is also where night training helps, because you learn things like paying attention to lights (including stars) that suddenly disappear: that means something is now between you and the lights, and you need to have a reasonable idea of what it is. A GPS with terrain features can be very useful.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Of course there are some specific challenges to flying at night, and they're addressed in training. There are &lt;a href=&quot;https://en.wikipedia.org/wiki/Sensory_illusions_in_aviation&quot; rel=&quot;nofollow noreferrer&quot;&gt;sensory illusions&lt;/a&gt; that only occur at night (or in very poor visibility), like black holes and autokinesis. There's also a tendency to fixate on the largest, most visible light sources and fly towards them even if it takes you off course. And judging height, distance and runway length are all a little different too, which is why pilots who haven't flown at night for some time should always go up with an instructor first, to refresh their memory.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-04-25T19:23:55.837" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27162" PostTypeId="2" ParentId="27127" CreationDate="2016-04-25T20:10:17.390" Score="3" Body="&lt;p&gt;This isn't a very satisfying answer, but as far as I can tell (after a lot of searching) there's no formal definition.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A lot of discussions about this start from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp&amp;amp;r=PART&amp;amp;n=14y2.0.1.1.2#se14.2.61_13&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 61.3&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No person may act as pilot in command of a civil aircraft under IFR or&#xA;  in weather conditions less than the minimums prescribed for VFR flight&#xA;  unless that person holds [an instrument rating and is current]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If that's what you were thinking about, the universal consensus on pilot forums is that by reading back an IFR clearance you're accepting it, and from that moment the flight is operating under IFR. However, there seems to be no explicit regulation or statement from the FAA to confirm it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, I couldn't find a definition (P/CG, 14 CFR 1.1 etc.) or FAA legal interpretation of what &quot;accepting&quot; a clearance of &lt;em&gt;any&lt;/em&gt; kind actually means. The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM&lt;/a&gt; and the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC orders&lt;/a&gt; both refer to &quot;acknowledging&quot; clearances, e.g. in the ATC Orders (section 2-4-3):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;pilots may acknowledge clearances, control instructions, or other&#xA;  information by using “Wilco,” “Roger,” “Affirmative,” or other words&#xA;  or remarks with their aircraft identification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the AIM mentions some scenarios where a readback - as opposed to an acknowledgement - is required, e.g. this from section 4-4-7:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots of airborne aircraft should read back those parts of ATC&#xA;  clearances and instructions containing altitude assignments, vectors,&#xA;  or runway assignments as a means of mutual verification.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But practically speaking, when ATC issues a clearance or instruction there are only three basic options:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The pilot reads back the clearance correctly (or ATC asks again until he gets it right)&lt;/li&gt;&#xA;&lt;li&gt;The pilot acknowledges without a readback (and ATC accepts that, or asks for a readback)&lt;/li&gt;&#xA;&lt;li&gt;The pilot says &quot;unable&quot; or asks for a different clearance&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In case 1, it seems reasonable that the correct readback is the acceptance, because the pilot didn't decline the clearance or ask for a different one. In case 2, the acknowledgement is the acceptance for the same reason (I can't think of a good example offhand; see &lt;a href=&quot;https://aviation.stackexchange.com/q/279/62&quot;&gt;this question&lt;/a&gt;). In case 3, the pilot is declining the clearance anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Personally, I think there's no formal definition  because it just isn't necessary. It seems obvious that by reading something back or saying &quot;roger&quot; you're agreeing to follow ATC's instructions, and I think it would be very difficult to argue differently.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-04-25T20:10:17.390" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27163" PostTypeId="2" ParentId="27138" CreationDate="2016-04-25T20:19:45.793" Score="0" Body="&lt;p&gt;You ask a very broad question. Jet engine technicians can work in various capacities depending on the job they are hired to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my experience, I worked on the flight-line directly on aircraft removing/installing, performing operational checks, troubleshooting and servicing engines and other systems.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some technicians work on engines out of the aircraft and in a controlled environment like the factories where engines are made. Others work in repair shops tearing down and rebuilding existing engines.&lt;/p&gt;&#xA;" OwnerUserId="2127" LastActivityDate="2016-04-25T20:19:45.793" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27164" PostTypeId="1" CreationDate="2016-04-25T21:06:57.863" Score="10" ViewCount="561" Body="&lt;p&gt;In &lt;a href=&quot;http://www.swissinfo.ch/eng/si2-fast-facts_10-questions-about-the-solar-impulse---answered/41329902&quot;&gt;this&lt;/a&gt; article the author explains that the aircraft flies at a lower altitude to conserve energy. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;During the day, it climbs to its maximum cruising altitude of 8,500 metres to capture the most rays. To conserve energy, it works its way down to 1,500 metres in the evening, and stays there overnight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How is this possible?&lt;/p&gt;&#xA;" OwnerUserId="14643" LastEditorUserId="13197" LastEditDate="2016-04-27T21:21:26.987" LastActivityDate="2016-04-27T22:27:42.590" Title="How does lowering altitude conserve energy in Solar Impulse 2?" Tags="&lt;solar-impulse&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27165" PostTypeId="1" CreationDate="2016-04-25T22:35:49.050" Score="1" ViewCount="329" Body="&lt;p&gt;What, if anything, does the phrase, &quot;clear to maneuver&quot; mean if given by an FAA airspace controller?&lt;/p&gt;&#xA;" OwnerUserId="14645" LastEditorUserId="62" LastEditDate="2016-04-25T23:20:38.853" LastActivityDate="2016-04-26T12:53:24.123" Title="What does the phrase from the FAA, &quot;clear to maneuver&quot; mean?" Tags="&lt;air-traffic-control&gt;&lt;usa&gt;&lt;phraseology&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27166" PostTypeId="2" ParentId="27164" CreationDate="2016-04-25T22:46:43.523" Score="13" Body="&lt;p&gt;Generally, best range is at high altitude(thin air, less drag), and best endurance is at low attitude(thick air, more lift) and low power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes sense that at night they would have to descend to a best endurance altitude to conserve battery power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/de9nw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/de9nw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;Source: &lt;a href=&quot;http://blog.solarimpulse.com/post/140441354990/second-training-flight-completed&quot; rel=&quot;nofollow noreferrer&quot;&gt;solarimpulse.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-04-26T11:37:01.903" LastActivityDate="2016-04-26T11:37:01.903" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27167" PostTypeId="2" ParentId="27151" CreationDate="2016-04-25T23:12:40.340" Score="3" Body="&lt;p&gt;Would the stopping distance perhaps increase instead of decrease from using the canard as an air brake?  My career involved stopping performance calculations for conventional airliners rather than delta wing configurations, but it seems that with existing landing technique you are getting a lot of drag benefit from the angle of attack of that big inefficient delta wing while the nose gear is still in the air.  Maybe more drag than there is to be had from getting the nose on the ground relatively quickly so that a smallish canard can be rotated? To come out ahead, it might be necessary to have the canard air brake activate prior to nose gear touchdown.  That would likely require automated real-time adjustment of the elevons to counteract the transitory moments, and perhaps a non-90 degree canard deployment angle during rollout to reduce the undesirable  moment coming from a drag force well above the vertical CG.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even if it happened to be the case that the canard was already capable of being rotated to any desired angle, given all of the above considerations something like slightly bigger drag chutes would presumably be a much easier way to get the same result.&lt;/p&gt;&#xA;" OwnerUserId="14644" LastEditorUserId="14644" LastEditDate="2016-04-25T23:20:08.690" LastActivityDate="2016-04-25T23:20:08.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27168" PostTypeId="2" ParentId="27164" CreationDate="2016-04-25T23:37:43.340" Score="3" Body="&lt;p&gt;Altitude is energy.  A long shallow dive, from 8,500 to 1,500 meters, recaptures the energy that it cost to climb up during the day.  It is completely analogous to charging the batteries with solar power during the day and drawing that energy out of the battery at night.  &lt;/p&gt;&#xA;" OwnerUserId="291" LastActivityDate="2016-04-25T23:37:43.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27169" PostTypeId="1" AcceptedAnswerId="27172" CreationDate="2016-04-26T00:26:57.847" Score="4" ViewCount="2092" Body="&lt;p&gt;Let's say I read a PIREP as follows...&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;KATL UA/OV KATL/TM 1522/FL080/TP C210/SK SCT013-TOP079/WX FV05SM&#xA; HZ/TA M04/WV 24540KT/TB LGT/RM IN CLR.&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;I'm in KATL where the field elevation is 1,026, so if I were reading a METAR that reported bases at 013 I'd expect to enter the clouds at 2,300' MSL. I'm reading a PIREP here though, so based on this am I expecting to enter the bases as 1,300 MSL or 1,300 AGL? I have the same question with the tops.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastEditorUserId="3825" LastEditDate="2016-04-26T00:56:50.983" LastActivityDate="2016-04-26T03:17:36.880" Title="How are cloud bases and tops reported on PIREPS?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27170" PostTypeId="1" CreationDate="2016-04-26T01:52:24.417" Score="8" ViewCount="2562" Body="&lt;p&gt;What is this plane? It kept circling overhead and I managed to get a picture during one of it's passes. The only parts I could see was 4 piston engines, straight wings, and a tall tail with some obscure markings on it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NBLyW.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NBLyW.jpg&quot; alt=&quot;Pretty Picture of An Airplane in the sky.&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14648" LastEditorUserId="14648" LastEditDate="2019-08-28T23:36:24.470" LastActivityDate="2019-08-28T23:36:24.470" Title="What is this plane?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="27171" PostTypeId="2" ParentId="27170" CreationDate="2016-04-26T01:57:15.710" Score="20" Body="&lt;p&gt;This looks like a C-130, as features like the bulge for the landing gear make it fairly easy to make the comparison.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For reference, here is a C-130 in flight: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dmy4H.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dmy4H.jpg&quot; alt=&quot;image 1&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/cwT1Q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/cwT1Q.jpg&quot; alt=&quot;image 2&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first image even appears to have the same markings as shown in the footage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military practices quite often will require an aircraft to hold a position, and could have just been circling for that reason. These aircraft are primarily used for lifting and aerial refueling. I do not see any refueling pods on the reference though, so it appears to be an unconverted plane. &lt;/p&gt;&#xA;" OwnerUserId="4379" LastEditorUserId="4379" LastEditDate="2016-04-26T12:41:51.117" LastActivityDate="2016-04-26T12:41:51.117" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27172" PostTypeId="2" ParentId="27169" CreationDate="2016-04-26T02:15:27.757" Score="4" Body="&lt;p&gt;It depends. For a PIREP cloud Heights are &lt;a href=&quot;http://groundschool.prepware.com/cgi-bin/faraim.pl?subsection_id=310&quot; rel=&quot;nofollow&quot;&gt;reported as they are read by the pilot&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;FAR AIM 7-1-16(b)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... In reports disseminated as PIREPs, height references are given the same as received from pilots, that is, above MSL.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This means some conditions may be reported MSL as read of the altimeter at local barometer settings while others may be set at standard pressure and read from there. I would assume that altitude reports less than 18,000ft are MSL.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-26T03:17:36.880" LastActivityDate="2016-04-26T03:17:36.880" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27173" PostTypeId="2" ParentId="27164" CreationDate="2016-04-26T02:51:29.677" Score="4" Body="&lt;p&gt;It is basically gliding at night. Not pure gliding but a powered glide - similar to what normal aircraft do on landing approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Altitude is energy. We all know this from science class - height = potential energy. Therefore an aircraft that's climbing uses energy and an aircraft that's gliding gains energy (technically it converts potential energy to kinetic energy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, it has to be done properly since the aircraft has no way of generating power at night. This is why it can't be a pure glide - if it loses too much altitude it won't have enough charge left in the batteries to climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The glide requires a lot less energy than maintaining level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In effect, the aircraft uses altitude as a second type of &quot;battery&quot;.&lt;/p&gt;&#xA;" OwnerUserId="2117" LastActivityDate="2016-04-26T02:51:29.677" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27174" PostTypeId="2" ParentId="27158" CreationDate="2016-04-26T02:58:02.440" Score="2" Body="&lt;p&gt;As for your question about why no rudder is required, there are two methods for handling a crosswind.  One is &quot;crabbing&quot; and the other is &quot;slipping.&quot;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you crab, you point the nose of the airplane into the wind as described in the other answers and in your pictures.  This is an efficient way to deal with a crosswind over long distances, such as when cruising.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During landing, if you are still crabbing when the wheels touch down, it's very hard on the airplane and is called &quot;side-loading&quot; the landing gear.  Instead, a slip is used.  In a slip the ailerons are held towards the wind and the rudder is held away from the wind just enough to keep the nose from turning.  In this way the longitudinal axis of the airplane is still kept in line with your flight path, but some of your lift is being used to &quot;pull&quot; you up-wind and thus counteract the crosswind.  On most airplanes this is the method used right before touchdown.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the final/short final phase, pilots have different preferences for crab or slip technique.&lt;/p&gt;&#xA;" OwnerUserId="14651" LastActivityDate="2016-04-26T02:58:02.440" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27175" PostTypeId="2" ParentId="27165" CreationDate="2016-04-26T03:50:02.173" Score="0" Body="&lt;p&gt;It means, on the radar and from other information report available to the controller, it appears that no aircraft are in the way, and that the maneuver can be performed in time. No other aircraft appear to be coming in the area needed to perform the maneuver, in the time that the maneuver need to be performed. It also implies that the controller is aware and ready to respond in case of emergency.&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2016-04-26T03:50:02.173" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27176" PostTypeId="2" ParentId="82" CreationDate="2016-04-26T03:57:17.697" Score="1" Body="&lt;p&gt;Magnetic heading works with a compass. No need for electricity, no need for a radio, no need for satellites. If you have a failure of any navigation system, or main battery, your compass will tell you the magnetic pole (which is slightly different than the real pole, depending where you are in the globe). It's a safety feature. Satellite work great, when they work, and when your navigation system works. If your battery is dead or something get disconnected, you need some backup that works! You can't say &quot;I lost my battery fuse for my navigation, therefore I got lost and we are going to die&quot; you need a backup, that's why.&lt;/p&gt;&#xA;" OwnerUserId="8050" LastActivityDate="2016-04-26T03:57:17.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27177" PostTypeId="1" CreationDate="2016-04-26T05:29:15.513" Score="2" ViewCount="220" Body="&lt;p&gt;Myth or Fact? Why are U.K/British pilots struggling to find their first job, then once they get the hours are still struggling? The question Is... Is it easier to get a job being a American Aviator Or British Aviator. For Aviation &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are even TV Shows about pilots having to travel across the world just to find work with a British passport. Worst Place To Be A Pilot - Season 1 / Episode 3 - Full Episode &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Meanwhile, CNN posted an article that U.S American pilots are in heavy demand and big companies are practically kicking down the door for new pilots. I list my sources so you know what I'm talking about. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a fact that U.S student pilots are having trouble paying for training with the U.S economy or is it because there are harsher rules for Americans so now less people are meeting the requirements? Are older pilots retiring? etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sNfeK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sNfeK.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA; I would hyper link but I don't have enough reputation points &lt;/p&gt;&#xA;" OwnerUserId="14641" LastEditorUserId="14641" LastEditDate="2016-04-27T16:11:52.970" LastActivityDate="2016-04-27T16:11:52.970" Title="Myth or Fact? U.K pilots struggling for work while U.S big airlines are kicking down the door for pilots with an American passport" Tags="&lt;flight-training&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="2" ClosedDate="2016-04-26T12:12:55.327" ContentLicense="CC BY-SA 3.0" />
  <row Id="27179" PostTypeId="2" ParentId="3052" CreationDate="2016-04-26T10:28:34.790" Score="22" Body="&lt;p&gt;The &lt;a href=&quot;http://opensky-network.org&quot;&gt;OpenSky Network&lt;/a&gt; has a free open-source API for real-time air traffic data. In its current version it allows users to retrieve live (and partially historical data). The data is retrieved by a network of ADS-B receivers and consists of&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;ICAO 24-bit transponder ID to identify the aircraft&lt;/li&gt;&#xA;&lt;li&gt;the flight's callsign&lt;/li&gt;&#xA;&lt;li&gt;aircraft's current location (latitude, longitude, altitude)&lt;/li&gt;&#xA;&lt;li&gt;aircraft's current horizontal and vertical velocity plus heading&lt;/li&gt;&#xA;&lt;li&gt;Unix timestamps which indicate the age of each field&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It's a REST API which provides all these data in JSON. They also provide simple Java and Python bindings. Their official API documentation can be found &lt;a href=&quot;https://opensky-network.org/apidoc/&quot;&gt;here&lt;/a&gt;. The sources for the Java and Python bindings are on &lt;a href=&quot;https://github.com/openskynetwork/opensky-api&quot;&gt;github&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="14656" LastEditorUserId="14656" LastEditDate="2016-04-26T12:13:00.580" LastActivityDate="2016-04-26T12:13:00.580" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27180" PostTypeId="1" AcceptedAnswerId="30425" CreationDate="2016-04-26T10:37:52.440" Score="6" ViewCount="24142" Body="&lt;p&gt;I wonder which of these has higher or lower rotational speed:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;turboshaft&lt;/li&gt;&#xA;&lt;li&gt;turbofan&lt;/li&gt;&#xA;&lt;li&gt;turbojet&lt;/li&gt;&#xA;&lt;li&gt;turboprop&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Does anybody know the typical speeds for these kind of engines? &lt;/p&gt;&#xA;" OwnerUserId="637" LastEditorUserId="1467" LastEditDate="2016-04-26T10:42:11.140" LastActivityDate="2020-01-10T21:35:20.880" Title="Which are typical rpm values for aeronautical turbines?" Tags="&lt;jet-engine&gt;&lt;turboprop&gt;&lt;turbine&gt;&lt;turbofan&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27181" PostTypeId="1" CreationDate="2016-04-26T12:16:07.410" Score="3" ViewCount="1224" Body="&lt;p&gt;Does &lt;em&gt;any&lt;/em&gt; country legally require the window blinds to be open for takeoff and landing? I'm asking about legal regulations that specifically mention window blinds, not airline procedures or general 'follow the crew instructions' regulations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I only need one example, whether it's FAA, EASA, a national CAA or some other regulator, or an ICAO standard or recommendation.&lt;/p&gt;&#xA;" OwnerUserId="14657" LastEditorUserId="14957" LastEditDate="2016-07-21T13:45:30.683" LastActivityDate="2016-07-21T13:45:30.683" Title="Is there any country that requires window blinds to be open for takeoff and landing?" Tags="&lt;faa-regulations&gt;&lt;airliner&gt;&lt;easa-regulations&gt;&lt;regulations&gt;&lt;caa-uk-regulations&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27182" PostTypeId="2" ParentId="27158" CreationDate="2016-04-26T12:52:36.347" Score="4" Body="&lt;p&gt;A change of reference frame may help to understand. So you sit in the plane and fly as usual, the only effect of wind is drifting the ground in the direction where it comes from. Headwind moves the ground forward, tailwind backwards. Sidewind to the side, so you compensate not by applying continuous rudder, but just by pointing the nose slightly to the side.&lt;/p&gt;&#xA;" OwnerUserId="2345" LastActivityDate="2016-04-26T12:52:36.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27183" PostTypeId="2" ParentId="27165" CreationDate="2016-04-26T12:53:24.123" Score="1" Body="&lt;p&gt;That isn't standard FAA phraseology; at least, it isn't anywhere in &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;the ATC orders&lt;/a&gt;. The closest thing is in section 9-2-20 on evasive action maneuvers. I know nothing about them, but they seem to be a military training thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;PHRASEOLOGY−&lt;/strong&gt;&lt;br&gt;&#xA;  CLEARED TO CONDUCT EVASIVE ACTION MANEUVER FROM (fix) TO&#xA;  (fix),&lt;br&gt;&#xA;  and&lt;br&gt;&#xA;  (number of miles) EITHER SIDE OF CENTERLINE,&lt;br&gt;&#xA;  and&lt;br&gt;&#xA;  MAINTAIN&#xA;  (altitude) THROUGH (altitude),&lt;br&gt;&#xA;  and&lt;br&gt;&#xA;  COMPLETE MANEUVER AT (fix) AT&#xA;  (altitude)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But of course both pilots and controllers use non-standard phraseology all the time, especially for unusual situations. It's certainly possible that a controller somewhere has indeed said &quot;cleared to maneuver as requested&quot; or something similar. Although the 'correct' phraseology would be &quot;approved as requested&quot; (see section 2-1-18 of the orders) for a general request.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another possibility is that it's military phraseology, not civilian. If you can link to a source or ATC recording then you might get a better answer.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-04-26T12:53:24.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27184" PostTypeId="2" ParentId="27158" CreationDate="2016-04-26T14:13:01.677" Score="1" Body="&lt;p&gt;In general: as Jay Carr visualized with his interactive graphic, velocities (speeds) are vectors (this is rather physics than aviatic, but if pilots consider physics they tend to live longer). Vectores have a value and a direction. So you can visualizes them by an arrow (lenght visualizes the velocity). Contrary to e.g. temperature which is a scalar measure, it has only a value but no direction. &#xA;So to add speeds you must consider values and directions. &#xA;Now to your questions ...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ad Image 1) &#xA;The wind is blowing from the left. If the aircraft would aim to the north (&quot;heading north&quot;), the cross wind would move it to the right, so it would pass the city more to its right (if map is oriented &quot;north up&quot; than it would pass the city east). &#xA;BUT, the pilot is smart: he compensates for the crosswind by pointing the aircraft's nose slightly &quot;into the wind&quot; (look, where the aircraft's noise is pointing to). Durign his flight planning he might have calculated the &quot;offset&quot; comparing desired track and forecasted wind. Once in the air he could also find out by applying a heading into the wind and check whether the aircraft moves along the desired track.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ad image 2) &#xA;the plane is sliding (well, it does not touch the ground) because its air speed (caused by the propulsion of the prop and being straight - visualized in the image by the wake vortices and its wing tips ) points to its noise (the prop is mounted without pivot), plus (plus in a sense of vector addition) the wind from the left result here in a track following the railways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ad image 3) &#xA;the wind from the left moves the whole air which surrounds the aircraft (a static wind, no gusts). So the while the aircraft moves through this air mass, the air mass itself (and with it the aircraft) moves along the wind direction. So you do not need rudder to hold that direction (heading). You only have to apply rudder to change the direction. So the pilot did apply rudder for some seconds when he noted that he needs to compensate for the crosswind, just until the aircraft changed its direction from north to slighly north-north-west.&#xA;The author says &quot;the aircraft does note feel the crosswind&quot; - yeah, due to its static effect you could not tell without any reference (to the ground, to your GPS or whatever navigation aid) that there is a wind at all. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To bring Wurzel's answer into the context: yes, if you want to land then you could use the same maneuver as shown in the 3 images (called crab, because this animal walks sideways), - or if you could fly straight along the runway direction but compensate for the crosswind by lowering the windward wing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hope it helps&#xA;Holger&lt;/p&gt;&#xA;" OwnerUserId="14658" LastActivityDate="2016-04-26T14:13:01.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27185" PostTypeId="2" ParentId="24316" CreationDate="2016-04-26T14:36:52.987" Score="1" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;For common procedures and or VFR rules you want to check the respective countries' AIP:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Switzerland   &lt;a href=&quot;http://www.skyguide.ch/en/services/aim-services/&quot; rel=&quot;nofollow&quot;&gt;http://www.skyguide.ch/en/services/aim-services/&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;the other countries you mentioned can be found from this link collection &lt;a href=&quot;http://www.eddh.de/equipment/ais.html&quot; rel=&quot;nofollow&quot;&gt;http://www.eddh.de/equipment/ais.html&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;you may want to check the website of Eurocontrol here you can find IFR standard arrivals and departures&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;No warranty! Please prepare your flight carefully.&lt;/p&gt;&#xA;" OwnerUserId="14658" LastEditorUserId="1467" LastEditDate="2016-04-26T15:06:46.027" LastActivityDate="2016-04-26T15:06:46.027" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27186" PostTypeId="2" ParentId="12303" CreationDate="2016-04-26T15:10:40.617" Score="4" Body="&lt;p&gt;My dad, an experienced pilot, was once given the chance to fly a 727 simulator (full motion, the works). He stalled it 40 feet over the runway and the simulator came down hard enough on the stops to hurt his back and scramble the gyros.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's only one data point, but any rate, the crash would have been survivable, so there's that.&lt;/p&gt;&#xA;" OwnerUserId="87" LastActivityDate="2016-04-26T15:10:40.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27188" PostTypeId="1" CreationDate="2016-04-26T16:50:19.373" Score="2" ViewCount="491" Body="&lt;p&gt;I've been trying to get my head around wing design and have been following a few YouTube videos. When people talk about aspect ratio (AR) on a wing and give a value (Piper PA28 having an AR of 5.7) what is the 5.7? Is it wingspan length? Square metre of coverage? Or something else? I'm confused.&lt;/p&gt;&#xA;" OwnerUserId="14660" LastEditorUserId="1696" LastEditDate="2016-07-05T19:32:33.383" LastActivityDate="2016-07-05T19:32:33.383" Title="What is the aspect ratio of a wing?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-04-26T20:27:01.643" ContentLicense="CC BY-SA 3.0" />
  <row Id="27189" PostTypeId="1" CreationDate="2016-04-26T16:58:57.010" Score="2" ViewCount="431" Body="&lt;p&gt;I understood that Oswald coefficient doesn't modify the induced drag (i.e. =1) if the lift distribution is elliptical.&#xA;When is the lift distribution not elliptical? What are the physical or ideal causes?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="1467" LastEditDate="2016-04-26T17:20:52.267" LastActivityDate="2016-04-26T17:21:02.020" Title="In which cases the lift distribution is not elliptical? (i.e. e≠1)" Tags="&lt;aerodynamics&gt;&lt;aircraft-structures&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27190" PostTypeId="2" ParentId="27188" CreationDate="2016-04-26T16:59:49.383" Score="0" Body="&lt;p&gt;The Aspect Ratio ($AR$) is defined as the ratio (hence the name) between the wingspan squared $b^2$ and the area of the wing $S$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since both $b^2$ and $S$ are measured with a length squared (e.g., $m^2$), $AR$ is an dimensionless quantity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer the follow-on question of TomMcW in the comments, $b$ is the distance between the wingtips, no matter the shape of the wing.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-04-26T17:21:58.367" LastActivityDate="2016-04-26T17:21:58.367" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27191" PostTypeId="2" ParentId="27189" CreationDate="2016-04-26T17:11:47.013" Score="1" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;When is the lift distribution not elliptical?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The distribution is non elliptical basically always, you have to struggle quite a lot to achieve an elliptical distribution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know only the Spitfire managed to decently approximate the elliptical distribution, and even then, the unavoidable presence of the fuselage had its consequences.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the physical or ideal causes?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Ideal? I think you are confusing what is ideal here. The ideal case is the elliptical distribution, since it gives you the minimal induced drag for equivalent lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As basic theory goes, you can have an elliptical distribution with an elliptical wing (is a consequence of the so-called &lt;a href=&quot;https://en.wikipedia.org/wiki/Lifting-line_theory&quot; rel=&quot;nofollow&quot;&gt;lifting-line theory&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-04-26T17:21:02.020" LastActivityDate="2016-04-26T17:21:02.020" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27192" PostTypeId="2" ParentId="27148" CreationDate="2016-04-26T17:13:39.250" Score="2" Body="&lt;p&gt;That frequency range is not for navigation equipment at all, so I would speculate that it isn't related to the navigation system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They don't receive two types of signals; they do the exact same thing, but the reason someone may want two radios is to make things easier during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I think you are seeing is your primary communications radio system, and then a switch for an additional, optional &quot;Com 2&quot; unit that may or may not be installed in the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you are talking to air traffic control, and you want to listen to an automated weather station without having to leave the ATC frequency; most systems provide you with an option to listen to both Com 1 and Com 2 at the same time, while allowing you to transmit on only one of them.  That way, you could monitor and talk on ATC's frequency on Com 1 while getting a weather update on Com 2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another advantage is that you can transition between frequencies faster by simply changing from Com 1 to Com 2 (ie. &quot;AUX COM&quot;) after having already set the frequency you want to switch to in the other Com.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet another advantage is that one com will act as a backup to the other if either one stops working for some reason.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-04-26T17:13:39.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27193" PostTypeId="2" ParentId="27127" CreationDate="2016-04-26T17:40:05.293" Score="6" Body="&lt;p&gt;I would try to not over complicate this issue.  There are three conditions a clearance/instruction can have:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Transmitted/Received&lt;/li&gt;&#xA;&lt;li&gt;Accepted&lt;/li&gt;&#xA;&lt;li&gt;Rejected&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;If ATC provides a clearance/instruction, but has not yet received a response, the clearance/instruction has not been accepted or rejected.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;If the pilot acknowledges the clearance/instruction with a read-back or affirmation of understanding, then it is accepted.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot responds with the term &lt;strong&gt;&quot;unable&quot; to any element of the clearance/instruction, then the &lt;em&gt;entire clearance/instruction set&lt;/em&gt; is rejected&lt;/strong&gt;, which may prompt ATC to inquire as to why the clearance/instruction is being rejected or to provide a different clearance/instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Per 91.3 the pilot-in-command reserves the right to act as the final authority as to the operation of the aircraft, but once a clearance/instruction is accepted, it is an indication that the pilot-in-command is agreeing, as the authority of operation, to operate by that clearance/instruction until released from it or forced to deviate due to an emergency or TCAS alert.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;One note for safety:&lt;/em&gt;&lt;/strong&gt; to be clear, one cannot simply reject one element of a clearance/instruction without rejecting the entire clearance/instruction.  For example, if ATC issues a turn and a climb, but the pilot's aircraft cannot or may not climb higher for whatever reason, the pilot should not read back the new heading and say, &quot;unable climb,&quot; and then turn to the heading and wait for more instructions.  What if the climb is to avoid obstructions that exist on the new heading?&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-06-08T16:19:34.623" LastActivityDate="2016-06-08T16:19:34.623" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27194" PostTypeId="1" AcceptedAnswerId="27197" CreationDate="2016-04-26T19:08:32.183" Score="0" ViewCount="558" Body="&lt;p&gt;I was just wondering if any one knows if the piper Aztec has flaps and what kind. Also if the piper Aztec has any other high lift devices.&lt;/p&gt;&#xA;" OwnerUserId="14663" LastEditorUserId="1467" LastEditDate="2016-04-26T19:13:25.603" LastActivityDate="2016-04-26T19:48:39.403" Title="Does the Piper Aztec have flaps and slats and if so what kind?" Tags="&lt;aerodynamics&gt;&lt;commercial-aviation&gt;&lt;flaps&gt;&lt;slats&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27195" PostTypeId="2" ParentId="27148" CreationDate="2016-04-26T19:13:50.667" Score="1" Body="&lt;p&gt;This may be in reference to the precision of band devision used in radio communications. Most older aircraft radios are only tunable to the 0.00MHz frequencies, while some newer ones may be sensitive enough to tune into 0.000MHz bands. Generally when tuned to say 120.00 on an older radio you will be able to pick up 120.00 as well as 120.005 while some planes are now capable of discreetly tuning to these frequencies. Thus AUX COM signals are those that live in the .000 bands    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-04-26T19:13:50.667" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27197" PostTypeId="2" ParentId="27194" CreationDate="2016-04-26T19:37:15.620" Score="7" Body="&lt;p&gt;The Piper Aztec has standard (plain) flaps:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/g708n.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g708n.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://sky4buy.com/1964-PIPER-PA-23-250-AZTEC-AIRFRAME-NICE-INTERIOR-GEAR-UP-DAMAGE-CHEAP-381236610083/01918&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sky4Buy.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another View:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zX8Fb.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zX8Fb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: Same as above&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Aztec does not have slats as can be seen in the image from the front of the wing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/p5Rk5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/p5Rk5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://www.nwaviators.com/aztec/aztec_pics.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;NWAviators.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a close-up view of the wing of the plane in the first two images (damaged, but no slats):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WYW7f.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WYW7f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;http://sky4buy.com/1964-PIPER-PA-23-250-AZTEC-AIRFRAME-NICE-INTERIOR-GEAR-UP-DAMAGE-CHEAP-381236610083/01918&quot; rel=&quot;nofollow noreferrer&quot;&gt;Sky4Buy.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than the flaps (and wings) there are no other high-lift devices installed on a Piper Aztec.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-26T19:48:39.403" LastActivityDate="2016-04-26T19:48:39.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27198" PostTypeId="1" CreationDate="2016-04-26T20:26:22.277" Score="2" ViewCount="152" Body="&lt;p&gt;Sorry for the complicated Question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering (&lt;a href=&quot;http://avherald.com/h?article=4953b8f6&quot; rel=&quot;nofollow&quot;&gt;after reading this report&lt;/a&gt;) if a two-engine air plane has an alternative operating scheme/setting for the remaining engine. Maybe a setting which is not that fuel efficient but more stable with respect to compressor surge and stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the cited report one engine suffered compressor stall (maybe by bird-strike) and was subsequently shut down. The other engine was reported to have left a trail.&lt;/p&gt;&#xA;" OwnerUserId="11294" LastActivityDate="2016-04-26T20:46:51.677" Title="Is there an alternative (more robust) operating law/setting for jet-engines? After one engine failed?" Tags="&lt;jet-engine&gt;&lt;engine-failure&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27199" PostTypeId="1" AcceptedAnswerId="27202" CreationDate="2016-04-26T20:35:06.583" Score="4" ViewCount="7687" Body="&lt;p&gt;In browsing Trade-a-Plane for my dream (light GA) ride, I often note the TBO (Time Before Overhaul) for an aircraft in relation to its asking price.  Obviously, the more time left before an overhaul is due, the greater the value of the airplane compared to one that is near or beyond its overhaul due date (hours).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always assumed this was an airworthiness item, meaning the aircraft was illegal to fly if it was overdue for a major overhaul.  But now I'm not so sure.  I've seen aircraft advertised as having a relatively recent top overhaul while being overdue for a major overhaul and I've seen a couple advertised that were overdue with no recent work done. Is a GA aircraft legal to fly if it's overdue for maintenance, and what are the exact rules for this?&lt;/p&gt;&#xA;" OwnerUserId="9161" LastEditorUserId="62" LastEditDate="2016-04-26T20:42:53.670" LastActivityDate="2016-04-27T04:10:59.497" Title="Is TBO an airworthiness item or just a recommendation?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;aircraft-maintenance&gt;&lt;piston-engine&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27200" PostTypeId="2" ParentId="27198" CreationDate="2016-04-26T20:46:51.677" Score="2" Body="&lt;p&gt;Aircrews regularly practice emergency procedures for engine out scenarios in their training and simulations. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft manufacturers and airlines provide procedural outlines for various possible emergency conditions specific to the type of aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;During an in flight emergency, fuel efficiency is not a priority. The aircrew is to ensure safe flight of the aircraft and the priority becomes landing quickly and safely. This may require use of the engine in any fashion to keep the aircraft in flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the report you reference, there is no real way to know what (if anything) caused what appeared to be a trail of smoke seen by another person in another aircraft waiting to take off. &lt;/p&gt;&#xA;" OwnerUserId="2127" LastActivityDate="2016-04-26T20:46:51.677" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27201" PostTypeId="1" CreationDate="2016-04-26T21:24:19.550" Score="2" ViewCount="1608" Body="&lt;p&gt;It is known how &lt;em&gt;stabilizers&lt;/em&gt; affect the longitudinal stability of an airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about longitudinal stability in airplanes using &lt;em&gt;stabilators&lt;/em&gt; (all-flying tails) or trimmable stabilizers?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it to be expected that certain combinations of angles of attack of the main wing and stabilators or trimmable stabilizers should lead to longitudinal instabilities?&lt;/p&gt;&#xA;" OwnerUserId="14665" LastEditorUserId="1467" LastEditDate="2016-04-27T09:16:29.123" LastActivityDate="2016-04-27T09:16:29.123" Title="What difference is there between stabilizers and stabilators concerning longitudinal stability?" Tags="&lt;aircraft-design&gt;&lt;stability&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27202" PostTypeId="2" ParentId="27199" CreationDate="2016-04-26T21:30:08.010" Score="10" Body="&lt;p&gt;Unless there is a TBO Airworthyness Directive for that particular engine/airframe/serial number, it is not illegal for GA operations to fly beyond TBO. I can't find an example of a TBO AD but I do remember seeing some.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TBO is a manufacturer recommendation for that particular engine, and does not have any legal enforcement with the FAA. An engine that is well cared-for and has good compressions and clear oil screens (along with other positive inspections) is perfectly fine to fly beyond TBO. There are even stories of people flying 1000 hours or more beyond TBO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here are some good reads from around the web:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.avweb.com/news/savvyaviator/187037-1.html&quot;&gt;The Savvy Aviator - Debunking TBO&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://flighttraining.aopa.org/magazine/1998/November/199811_FT_Owner_Engine_Overhauls.html&quot;&gt;AOPA Engine Overhauls&lt;/a&gt;&lt;br/&gt;&#xA;&lt;a href=&quot;http://www.aviationlawmonitor.com/2009/12/articles/claims-and-defenses/running-past-tbo-smart-economics-or-owner-negligence/&quot;&gt;Aviation Law - Flying Past TBO, Negligence or Smart Economics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case, flying beyond TBO is controversial. Some say that an engine near or over TBO is less likely to fail than one that has been recently taken apart, or at least less likely to fail suddenly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The key aspect though when buying used aircraft is you don't know how the engine was treated in its run up to TBO. Was it shock cooled? Used for training? Operated out of a grass strip? Poor maintenance? Flown rarely? There are way too many conditions to consider when buying an aircraft near TBO to make the judgement of going beyond it safely or not. The only person who can answer that question is an A&amp;amp;P. That is why TBO is tied so closely to the value of an aircraft. Engine overhauls are expensive, running $25k or more.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastActivityDate="2016-04-26T21:30:08.010" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27204" PostTypeId="1" AcceptedAnswerId="27208" CreationDate="2016-04-26T22:24:44.147" Score="9" ViewCount="433" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/12303/could-a-single-engine-pilot-land-a-passenger-jet-from-airplane&quot;&gt;Related question&lt;/a&gt;, but not a dupe as that's about starch-wings and the gap between light fixed-wing planes and fixed-wing transports does seem larger than the similar gap in rotorcraft...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say our good friend Simon, with his considerable amount of cyclic-time in small-to-modest helicopters, is onboard an S-76 (or other similar large helo) and both the pilots find out that the fish was a bad choice of preflight meal.  How much assistance would he need from someone on the ground with time-in-type in order to get the helicopter on the ground safely, assuming this was in VMC?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-04-27T06:33:49.933" Title="Could a light helicopter pilot land a transport-category helicopter?" Tags="&lt;landing&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27205" PostTypeId="2" ParentId="24023" CreationDate="2016-04-27T02:34:58.070" Score="5" Body="&lt;p&gt;Taxiway &quot;A&quot; at the approach end of runway 29R has the words &lt;code&gt;TAXI&lt;/code&gt; on the taxiway.  Many A-10 and F-16 pilots over the years have mistaken the parallel taxiway with the runway.  The primary is the approach is a &lt;code&gt;LOC BC&lt;/code&gt; and as such is a little more difficult than standard for training pilots.  They look up at MDA, right of center-line and see a long &quot;runway&quot; and not the taxiway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://binged.it/1SzlPiA&quot; rel=&quot;nofollow&quot;&gt;KTUS Aerial map runway 29R&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;I've personally trained pilots who have lined up on a taxiway.  Two things were apparent, they were both visual approaches with no instrument backup to reference and they both looked up assuming the runway was right in front... like it always is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One pilot commented he can't imagine a pilot mistaking a taxiway for a runway till he was circling one day and lined up on the parallel taxiway to the circling runway.  We talked about it afterwards, he said. &quot;Wow.  I swore that was the runway.  I identified the runway and my perception made it so... even though it wasn't.  I need to take more time to confirm what my perceptions are telling me.&quot;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2016-07-15T12:41:56.043" LastActivityDate="2016-07-15T12:41:56.043" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27206" PostTypeId="2" ParentId="27201" CreationDate="2016-04-27T03:29:04.943" Score="5" Body="&lt;p&gt;There is no fundamental difference between them in such context. If you don't go to the extremes like 90° deflection (and generally stay in the linear range), you can mentally replace an elevator with a stabilator at a different equivalent angle. All-moving surfaces are typically a design solution when additional efficiency is required for whatever reason.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are finer effects, especially at supersonic, but they don't change the overall picture for 'normal' aircraft. You can always find border cases when, say, elevator will stall but an equivalent stabilator will not yet, but they will generally be beyond the operational envelope.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stability is primarily determined by &lt;em&gt;derivatives&lt;/em&gt;, i.e. the way moments &lt;em&gt;change&lt;/em&gt; with changing angles (of attack in this case). Absolute angles (tail vs wing) are less important and are usually the &lt;em&gt;consequence&lt;/em&gt; of the desired derivatives.&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-04-27T03:29:04.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27208" PostTypeId="2" ParentId="27204" CreationDate="2016-04-27T05:39:21.610" Score="12" Body="&lt;p&gt;This is based on knowledge and a &lt;em&gt;little&lt;/em&gt; experience. I have flown a Wessex to a hover and they are big, heavy, powerful beasts. If your example &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;our good friend Simon&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;refers to me, then I must also state that I only have about 130 hours so &lt;em&gt;limited hours&lt;/em&gt; is more accurate :)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is said that if you can fly one helicopter, then you can fly another.  Indeed, I learned on the R22 and it's a &quot;fact&quot; (insofar as if enough people repeat something enough times, it becomes a &quot;fact&quot;) that if you can fly the R22, then you can fly anything because it demands careful handling and has very small power margins.  I have never heard a really experienced pilot refute that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we assume that you have enough fuel and that there is no complex fuel system which requires switching of pumps to keep the engines fed, then yes, you could land anything with one notable exception.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nearly all helicopters have a couple, either manual or automatic, between the demand for power (how much pitch you are asking for) and the engine power output.  Raise the collective and the throttle is automatically opened and vice-versa.  This is certainly true about transport category aircraft.  On something like early Hilliers, I would need to learn pretty fast that as I increase pitch, I must roll on throttle otherwise, I will stall when I try to climb or raise the lever to come into the hover.  This is practised during PPL but I must admit, I've never used manual throttle control since I got my license.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another area of concern would be over controlling but that's easy to deal with.  I am now thrust into the pilots seat of a type I don't know and I am not licensed for.  I am going to land on the nearest safe spot.  I'm not going to do anything fancy whatsoever so, if I need a descent, I will lower the lever gently and use the cyclic to maintain my speed. Then I'll climb a little by gently raising the cyclic until I start to climb.  All helicopters fly nicely at about 60 kts so I will pitch for that speed. The only thing I need to look at to ensure the limits aren't busted is airspeed.  Any helicopter pilot would get the feel of this in very little time as would any fixed wing pilot.  It's just a question of how heavy the controls are and how much they physically need to move but that's quickly explored by starting gently and using just enough to do what you need to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume that the subject craft does have automatic throttle control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will also assume that we are in VMC otherwise, we are all going to die.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are only two other areas of concern that I can think of and that's the type of the landing gear (skids vs wheels and how many) and the height of your seat above the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One major difference between rotaries and fixed wing is that there is no stall speed and all helicopters can land with the same forward speed and rate of descent.  I can, if I want to, bring the craft to a hover and stop to have a good think about what comes next.  To come into a hover is also easy.  You can do it by the numbers but the practical way is to keep your speed over the ground so that the site picture is apparently a fast walking speed and keep the landing spot in the centre of the window.  if the landing spot moves up, decrease your rate of descent and vice-versa.  Do this, and you will arrive close to the spot at a sensible speed and with a low rate of descent.  Vortex ring state won't be a concern for me.  I won't know at which speed I will lose translational lift but it will be somewhere between 10 and 15 kt, so I'll be waiting for that little shudder to start and the nose to swing a little, ready to bring in power and pedal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that most, perhaps all, wheeled transport helicopters have wheel brakes, but I will have no clue how use these.  So, I am going to land zero-zero and ensure that I am directly into wind and on a level surface.  The next think is how will I know when I've landed?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I first landed a B206, it was on my conversion course so I already knew how to land smoothly.  All I had to do to deal with the extra height I was sitting above the ground was &quot;feel&quot; the aircraft down.  It can be surprisingly difficult to know when a helicopter is fully on the ground and not flying it all the way down is one way to get into trouble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would deal with this by feeling for the first contact and then smoothly, but not too quickly, lowering the lever.  This does two things.  It ensures a firm contact and removes my biggest landing worry in an unfamiliar type which is dynamic rollover.  It won't be pretty and I might even get a blade strike somewhere but with power now off, we'll all walk away. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in summary, I wouldn't need any assistance but, if I can figure out where the transmit button is and how to tune the radio, I will try to get some anyway.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-04-27T06:33:49.933" LastActivityDate="2016-04-27T06:33:49.933" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27209" PostTypeId="1" AcceptedAnswerId="27230" CreationDate="2016-04-27T08:11:53.283" Score="7" ViewCount="1725" Body="&lt;p&gt;Past the cyclic-collective pitch control, I understand (maybe incorrectly) that additional mechanisms are required to prevent or limit vibrations and loads on the mast and the blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1Tu7N.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1Tu7N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Aerospatiale SA321G Super Frelon, photo by &lt;a href=&quot;http://www.b-domke.de/AviationImages.html&quot; rel=&quot;noreferrer&quot;&gt;Burkhard Domke&lt;/a&gt; (&lt;a href=&quot;http://www.b-domke.de/AviationImages/Rotorhead/15007.html&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are other rotor heads that are very simplified:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hgZ8a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hgZ8a.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Bell AH-1 Super Cobra (&lt;a href=&quot;http://www.wikiwand.com/en/Bell_AH-1_SuperCobra&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can you explain what are the &lt;em&gt;main&lt;/em&gt; mechanisms in the Super Frelon rotor head, and why the simple rotor head design is not used?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="1467" LastEditDate="2016-04-27T08:40:50.063" LastActivityDate="2021-03-30T16:25:31.430" Title="What are the mechanisms fitted in the SA321G Super Frelon rotor head?" Tags="&lt;helicopter&gt;&lt;rotor-head&gt;" AnswerCount="1" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27210" PostTypeId="1" AcceptedAnswerId="27245" CreationDate="2016-04-27T08:37:50.203" Score="2" ViewCount="1864" Body="&lt;p&gt;I am trying to learn more about airspaces. It would be nice if I had the airspace map of my region to look and observe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;skyvector.com shows very few information about Turkey, not useful.&lt;/p&gt;&#xA;" OwnerUserId="14589" LastEditorUserId="3201" LastEditDate="2016-04-28T09:47:42.383" LastActivityDate="2016-04-28T09:47:42.383" Title="Where can I find airspace maps for Turkey?" Tags="&lt;airspace&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27211" PostTypeId="1" AcceptedAnswerId="27213" CreationDate="2016-04-27T09:13:11.543" Score="11" ViewCount="9684" Body="&lt;p&gt;If the wing tanks of an A320 are fully filled and the fuel expands due to high temperatures then the fuel overflows into the vent tank. My question is, does the fuel get stored in the vent tank? If yes, how much? If not, does all of the fuel just spill on the ramp?&lt;/p&gt;&#xA;" OwnerUserId="11290" LastEditorUserId="62" LastEditDate="2016-04-27T10:09:58.820" LastActivityDate="2021-01-18T12:06:49.250" Title="What is the capacity of the vent surge tank in an A320?" Tags="&lt;aircraft-systems&gt;&lt;airbus-a320&gt;&lt;fuel-tanks&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27212" PostTypeId="1" CreationDate="2016-04-27T09:14:22.987" Score="2" ViewCount="956" Body="&lt;p&gt;What type of flaps, slats or other high-lift devices are used on this aircraft?&lt;/p&gt;&#xA;" OwnerUserId="14663" LastEditorUserId="62" LastEditDate="2016-04-27T10:10:47.167" LastActivityDate="2016-04-27T15:09:43.223" Title="What high-lift devices are used on the Bombardier Dash 8 Q400?" Tags="&lt;aerodynamics&gt;&lt;flaps&gt;&lt;slats&gt;&lt;dash-8&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27213" PostTypeId="2" ParentId="27211" CreationDate="2016-04-27T10:15:45.730" Score="15" Body="&lt;p&gt;From Airbus &lt;a href=&quot;http://www.smartcockpit.com/docs/A320-Fuel.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;flight crew operating manual (FCOM)&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AVMmX.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AVMmX.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The expansion tanks above the center tank allow the center tank to be filled to the maximum. Tanks capacity is 23,858 liters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FCOM says the fuel can expand up to 2 % without spillage in the vent/surge tanks. That's about 239 liters per surge tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The volumetric expansion of the fuel is about 0.095% per °C. 2% allows for a 21°C temperature increase.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The vent/surge tank communicates with the outer tank on the same side, and fuel can flow back by gravity, when conditions permit.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-04-27T11:38:49.627" LastActivityDate="2016-04-27T11:38:49.627" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27214" PostTypeId="1" CreationDate="2016-04-27T10:16:09.480" Score="2" ViewCount="483" Body="&lt;p&gt;The cabin temperature controller in commercial airlines, controls the cabin temperature. But if for any reason, it does not function, does the pilot have to make an emergency landing, or can he cruise to a lower altitude for normal temperatures?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2016-04-28T01:40:36.603" Title="If the cabin temperature controller does not function, does the pilot have to make an emergency landing?" Tags="&lt;emergency&gt;&lt;cabin-pressure&gt;&lt;cabin-design&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27215" PostTypeId="1" CreationDate="2016-04-27T10:45:33.507" Score="23" ViewCount="7120" Body="&lt;p&gt;I was on landing rollout and misheard a tower &quot;turn off at xxx switch ground&quot; call. We read back the incorrect taxi way and turned off there and switched to the ground frequency. After our incorrect read back we were not contacted again until ground told us to call tower. I was under the impression that the landing aircraft had the right of way over any traffic behind them, even on roll out. I was also under the impression that a tower cannot stop you from using the whole runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is missing a directed turn off a runway a flight violation? If so what FAR/AIM or regulation did it violate? Is the fault with us for mishearing or with the controller for not correcting us? Does this count as a runway incursion? Does the controller maintain responsibility for maintaining separation until we taxi clear?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer a few of the questions from below:&#xA;when we contacted the ground controller, they gave us a phone number to contact tower then gave us a taxi clearance. When they told us to call i became concerned with receiving a flight violation. We were not corrected to my knowledge, we only heard radio traffic once we had turned off the runway. This was also not a LAHS operation.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;another question: From the AIM 4-3-20 it says : &quot;the following procedures must be followed...&quot; &quot;exit the runway without delay&quot; &#xA;&quot; is that at the discretion of the pilot? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;also if tower gives you a taxiway instruction to leave the runway is that an instruction or a clearance?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it a good idea to call the local FAA office and see if they have opened an investigation? &lt;/p&gt;&#xA;" OwnerUserId="14667" LastEditorUserId="14667" LastEditDate="2016-04-28T18:02:40.040" LastActivityDate="2020-10-29T20:06:36.423" Title="Is it a flight violation to mishear ATC instructions for exiting the runway?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;air-traffic-control&gt;&lt;landing&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27217" PostTypeId="2" ParentId="27215" CreationDate="2016-04-27T13:54:58.513" Score="40" Body="&lt;p&gt;I don't think you violated any regulations. It was an ATC instruction, not an ATC clearance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was an instruction you were unable to comply with. The instruction was badly timed and was obviously not clear since you did not correctly understand it.  In the busy time during the landing roll, you understood something different, and read back what you understood it to be. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The landing roll-out can be a busy time needing the attention of both pilots.  ATC issuing an instruction while you are basically still in the landing roll should not be expected to be complied with unless it is happens to be convenient for you to do so.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many airlines SOP say that you do &lt;strong&gt;nothing&lt;/strong&gt; until you are clear of the runway. Both pilots remain heads up and don't touch anything. The pilot in command alone will decide where it is safe to tun off the runway. If ATC makes a &quot;Request&quot;, and it can be safely complied with, then the PIC may decide to deviate from SOP and comply. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you ran off the side of the runway trying to comply with an ATC &quot;request&quot;, who do you think will be held responsible? (I'll give you a hint, it won't be ATC)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a prime example of why ATC should not be doing this. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorDisplayName="user13148" LastEditDate="2016-04-27T15:56:48.433" LastActivityDate="2016-04-27T15:56:48.433" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27218" PostTypeId="2" ParentId="27215" CreationDate="2016-04-27T14:14:30.343" Score="15" Body="&lt;p&gt;Mike has a good answer, but I thought it was worth while mentioning something you say in your question:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...I was also under the impression that a tower cannot stop you from using the whole runway. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;While in many cases this is true, there are some that it is not. The main example of this is a &lt;a href=&quot;http://www.aopa.org/Pilot-Resources/Safety-and-Technique/Operations/Land-and-Hold-Short-Operations-LAHSO&quot;&gt;Land and Hold Short Operation (LAHSO)&lt;/a&gt;. If you accept a LAHSO then you are required to comply with the hold short point on the runway and not go beyond that. (The only other one I can think of is when a crossing runway is closed).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if you had accepted a LAHSO request (and its up to you as the pilot to accept or decline the request), and subsequently used more than the LAHSO permitted you to, this would be a violation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, if you are a light plane and want more than your fair share of runway, its usually &quot;polite&quot; to tell the controller that you want &quot;full length&quot;. The controller is trying to space out landing aircraft and may assume that you don't need 8000+ feet of runway in your Cessna 172. Legally unless you accept a LAHSO you are welcome to use all of it, but the controller will be a happier person if you tell them you need more. I do this quite a bit when coming in on a certain runway that has the FBO at the opposite end, its better to land long than spend 10 minutes taxing. The controller may request that you &quot;make it short&quot; for landing aircraft.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-04-27T14:26:05.300" LastActivityDate="2016-04-27T14:26:05.300" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27219" PostTypeId="1" AcceptedAnswerId="27235" CreationDate="2016-04-27T15:08:34.847" Score="10" ViewCount="1571" Body="&lt;p&gt;I may be wrong but I learned that control surfaces depends on the air flow to work properly, and that airliners have a higher cruise altitude because of the less dense atmosphere, improving the fuel efficiency.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But that got me thinking:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Will control surfaces on a plane be less effective at a higher altitude because of the less dense air?&lt;/li&gt;&#xA;&lt;li&gt;Do modern airliners have a workaround to solve this problem?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="1696" LastEditDate="2016-06-14T16:42:51.867" LastActivityDate="2016-06-14T16:42:51.867" Title="Will control surfaces on a plane be less efficient at a higher altitude?" Tags="&lt;airliner&gt;&lt;control-surfaces&gt;&lt;cruise&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27220" PostTypeId="2" ParentId="27212" CreationDate="2016-04-27T15:09:43.223" Score="2" Body="&lt;p&gt;The &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=4&amp;amp;ved=0ahUKEwj7qJ39ia_MAhUM6SYKHTglAp0QFggyMAM&amp;amp;url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath%3Ddocs%2F%26file%3DQ400-Aeroplane_General.pdf&amp;amp;usg=AFQjCNH4Tw3iAsebig88SxAZIaOTA2p0FA&amp;amp;cad=rja&quot; rel=&quot;nofollow&quot;&gt;Dash8 - Q400 - Aeroplane General&lt;/a&gt; PDF (courtesy of &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Q400-Flight_Controls.html&quot; rel=&quot;nofollow&quot;&gt;smartcockpit.com&lt;/a&gt;) indicates on page 27 that there are inboard and outboard flaps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Reading through the &lt;a href=&quot;http://www.smartcockpit.com/aircraft-ressources/Q400-Flight_Controls.html&quot; rel=&quot;nofollow&quot;&gt;Dash8 - Q400 Flight Controls&lt;/a&gt; PDF (also from smartcockpit.com) indicates that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Two single-slotted inboard and outboard fowler flaps are attached to the trailling edge of each wing (Figure 12.8-1).&lt;br&gt;&lt;sup&gt;page 43&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no indication of slats or any other high-lift device.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastActivityDate="2016-04-27T15:09:43.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27221" PostTypeId="1" AcceptedAnswerId="27222" CreationDate="2016-04-27T15:12:46.430" Score="9" ViewCount="1927" Body="&lt;p&gt;I'm definitely new to the site so apologies if this question is naive but google turned up no answers for me:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was reading &lt;a href=&quot;http://www.reuters.com/article/us-nuclearpower-cyber-germany-idUSKCN0XN2OS&quot; rel=&quot;noreferrer&quot;&gt;this article&lt;/a&gt; and read the following paragraph:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As an example, Hypponen said he had recently spoken to a European aircraft maker that said it cleans the cockpits of its planes every week of malware designed for Android phones. The malware spread to the planes only because factory employees were charging their phones with the USB port in the cockpit.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The question that immediately sprung to my mind was:  &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What is the intended purpose of USB port(s) in the plane cockpit?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Was it really intended for charging devices like phones? That seems naively insecure.&lt;/p&gt;&#xA;" OwnerUserId="14673" LastEditorUserId="13197" LastEditDate="2016-04-27T16:51:54.450" LastActivityDate="2016-04-27T18:43:47.353" Title="What is the purpose of a USB port in the cockpit?" Tags="&lt;cockpit&gt;" AnswerCount="1" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27222" PostTypeId="2" ParentId="27221" CreationDate="2016-04-27T15:21:25.763" Score="11" Body="&lt;p&gt;Some &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_management_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight Management System&lt;/a&gt; databases are &lt;a href=&quot;https://www.youtube.com/watch?v=COrjd-9xorY&quot; rel=&quot;nofollow noreferrer&quot;&gt;updated via USB stick&lt;/a&gt; and require a USB port. Since navigational databases are updated frequently and require a simple way to make an update, USB (or memory card slots) are generally used to allow for rapid and easy updates without having to remove any panels. In some cases the port may be in the avionics bay however that is usually easily accessed as well. It should be noted that a recent change in regulation now allows pilots to update nav data, &lt;a href=&quot;https://aviation.stackexchange.com/questions/1293/may-pilots-perform-fms-database-updates-under-part-135&quot;&gt;this question covers it well&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Was it really intended for charging devices like phones? That seems&#xA;  naively insecure.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally these ports are not for charging but the basic design of a USB port more or less always allows you to charge from it because of the nature of the port. The security on the ports is more about cockpit security. In most cases the security lies in making it difficult to get into the cockpit in the first place. It is often assumed now that if you are in the cockpit you should be there. There is of course many questions this opens up some of which have been answered here or would be good to ask about.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As iPads become more common in the cockpit for navigation and the such USB ports are &lt;a href=&quot;http://www.aircraftspruce.com/menus/el/powerconvert_cabin.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;becoming more commonplace on panels&lt;/a&gt; for charging but this seems to be more common in GA planes currently.&lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-27T18:43:47.353" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27225" PostTypeId="2" ParentId="27219" CreationDate="2016-04-27T15:58:39.243" Score="4" Body="&lt;p&gt;Control effectiveness is dependent on airflow. Flying slower or through thinner air makes the controls less effective. However, given the same indicated airspeed (IAS), the same number air molecules are passing by the control surfaces, so the effectiveness will be the same. Do note that a given IAS results in higher true airspeed (TAS) in thinner air (higher altitude).&lt;/p&gt;&#xA;" OwnerUserId="1520" LastActivityDate="2016-04-27T15:58:39.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27226" PostTypeId="1" AcceptedAnswerId="27258" CreationDate="2016-04-27T16:08:02.260" Score="9" ViewCount="368" Body="&lt;p&gt;I have never passed through class-C airspace without intending on landing at the primary airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the flight is conducted under VFR, and I am planning on landing at a satellite airport to the primary class-C, will approach control expect me to indicate that I have ATIS information from the primary airport, that I &quot;&lt;strong&gt;have numbers&lt;/strong&gt;&quot; for the satellite airport landing destination, or that I have both weather station information sets?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about just passing through their airspace with no intent to land nearby? Do they still expect that you indicate receipt of ATIS information?&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-06-25T13:50:51.573" LastActivityDate="2016-06-25T13:50:51.573" Title="What are approach control's expectations regarding weather information for flights to satellite airports?" Tags="&lt;visual-flight-rules&gt;&lt;atis&gt;&lt;class-c-airspace&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27228" PostTypeId="2" ParentId="27215" CreationDate="2016-04-27T16:59:25.150" Score="5" Body="&lt;p&gt;Exiting a runway is purely at the discretion of the PIC. The tower-recommended exit is just that: a recommendation. This is a safety issue. The pilot exits the runway where they and they alone decide it is safe to do so.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-27T16:59:25.150" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27229" PostTypeId="1" AcceptedAnswerId="27232" CreationDate="2016-04-27T17:02:07.367" Score="11" ViewCount="2412" Body="&lt;p&gt;I would like a clarification about requesting practice approaches.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen pilots at uncontrolled airports shoot practice approaches such as VOR, SDF, etc. without needing approval; obviously.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Am I correct in thinking that a practice approach approval is only required to be explicitly requested when being controlled by ATC via flight following or approach/tower control?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know this may seem like a silly question, so I will describe a scenario so that readers understand the context of why I am asking a little bit better:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A VFR flight passes through class C airspace, and contacts approach control prior to entering.  On the other side of said class C airspace, a few miles out of the boundary line, there is a destination airport where the pilots would like to shoot a practice approach, which is a non-controlled airport outside of the boundaries of &quot;ATC-contact-required&quot; airspace.  Do the pilots request a practice approach, or do they request to terminate radar service and then go ahead and shoot the approach?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe the answer lies in the content of the approach depending on whether or not initial fixes or a missed approach segment would lead a flight into &quot;ATC-contact-required&quot; airspace.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="62" LastEditDate="2016-04-28T08:26:35.960" LastActivityDate="2021-03-09T21:49:27.963" Title="When are pilots required to have approval to conduct practice approaches?" Tags="&lt;faa-regulations&gt;&lt;approach&gt;&lt;visual-flight-rules&gt;&lt;instrument-procedures&gt;" AnswerCount="4" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27230" PostTypeId="2" ParentId="27209" CreationDate="2016-04-27T17:07:10.467" Score="8" Body="&lt;p&gt;All rotor heads need to deal with multiple forces but two in particular have a big influence on the design and complexity of the rotor head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a blade moves forward (the advancing blade), it experiences an airflow equal to the speed of the blade plus the air speed.  As the blade moves backwards (the retreating blade), it experiences an airflow equal to the air speed minus the speed of the blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, the advancing blade generates more lift and will rise which causes the airflow to hit the blade with a more vertical component, reducing the angle of attack and the lift generated.  The opposite happens to the retreating blade.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This causes the advancing blade to flap up and the retreating blade to flap down.  The rotor head must allow this to happen and deal with the resulting forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second effect arises from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Coriolis_force&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coriolis effect&lt;/a&gt;.  This results in a force applied to the hub by each blade as it speeds up and down called lead/lag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are three main types of rotor head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.danubewings.com/fully-articulated-rotor-system/&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Fully articulated&lt;/strong&gt;&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/J3Mzt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/J3Mzt.jpg&quot; alt=&quot;From danubewings.com, copyright of FlightLearning.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.danubewings.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;From danubewings.com, copyright of FlightLearning.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades are attached to the hub with hinges that allow the blade to flap up and down and lead/lag (or drag) hinges around the hub, allowing these forces to be absorbed without applying them to the blade or the hub. The blades may also rotate in a cuff through which the blade is attached to the hub. Each blade can flap and lead/lag.  Note that dampers may also be fitted to reduce vibrations and to better absorb the forces. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These are the most complex heads, an example of which is in your first image.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.copters.com/mech/mr_semi.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Semi-rigid&lt;/strong&gt;&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/z2674.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/z2674.jpg&quot; alt=&quot;Copyright Copters.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.copters.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Copyright www.copters.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades are attached to the head with lead/lag hinges only.  Flapping is enabled by allowing the entire head to &quot;teeter&quot; on hub so that if one blades rises, the other must fall.  They cannot flap independently. Since the entire disc tilts together, semi-rigid heads can only have 2 blades.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The coning hinges allow both blades to move up and down together, without regard to where the teetering hinge is, as power is changed collectively.  So, the flapping (or teetering) hinge enables cyclic flapping whilst the coning hinge enables collective flapping. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.helistart.com/Pictures/RotorHeads/IMG_0189Hingless.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;strong&gt;Rigid&lt;/strong&gt;&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Vubt.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Vubt.jpg&quot; alt=&quot;Copyright helistart.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.helistart.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Copyright helistart.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blades are rigidly attached to the hub and the flapping and lead/lag forces are absorbed entirely through flexing of the blades.  This is the simplest of all heads.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The choice of rotor head type is a complex one with intended design and performance being primary drivers but, as the head gets more complex, rigid being the simplest and fully articulated being the most complex, the maintenance cost goes up and generally, so does the weight.  Conversely, fully articulate heads produce the lightest loads on the main rotor shaft, it's thrust bearings and the gearbox coupling allowing weight savings to be made there. Rigid heads also require the strongest blades, and therefore weight, although modern composites are enabling the manufacture of blades with high flexibility but lower weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The head you have shown is particularly complex as it is six bladed and has an automatic folding system so that it can be stored and hangared in small spaces and be ground manoeuvrable on aircraft carriers with limited deck space. The tail folds at the same time as the blades. Most of the stuff you can see apart from the blades, their cuffs and their hinges is hydraulic piping, pumps and motors, electrical bonding strips, sensors and transducers. There is also an oil lubrication system for the bearings - you can see the oil reservoir on the top of the hub.  The use of &lt;a href=&quot;https://en.wikipedia.org/wiki/Elastomer&quot; rel=&quot;nofollow noreferrer&quot;&gt;elastomers&lt;/a&gt; in bearings has removed a lot of the need for lubrication.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you stripped all of that it away, it wouldn't look (quite) so complex.  I.e. Not so barking mad!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zdynR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zdynR.jpg&quot; alt=&quot;Copyright helistart.com&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.helistart.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Copyright helistart.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-04-28T06:39:36.783" LastActivityDate="2016-04-28T06:39:36.783" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27231" PostTypeId="1" AcceptedAnswerId="29715" CreationDate="2016-04-27T17:08:30.503" Score="7" ViewCount="2338" Body="&lt;p&gt;I'm not an expert but as I understand autogyro sustentation relies on the rotor. If the rotor breaks, the aircraft will fall as a rock to the ground... But If the autogyro was built as a tractor design and had wings as the first cierva autogyros did: Would it survive to a rotor destruction? In case of rotor breaking the pilot maybe has a chance to glide and do an emergency landing. Is it safe to build an autogyro with wings? Does it have an increased operational cost?&lt;/p&gt;&#xA;&lt;p&gt;Note that having wings add the  incovenience of being afected more by the turbulences and wind.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5kGRJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5kGRJ.jpg&quot; alt=&quot;Cierva Tractor Aurogyro with Wings&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14675" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2017-11-15T21:23:42.277" Title="Can an Autogyro with wings survive a rotor mechanical failure? Will it be safer?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;wing&gt;&lt;auto-rotation&gt;&lt;autogyro&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27232" PostTypeId="2" ParentId="27229" CreationDate="2016-04-27T17:39:37.660" Score="7" Body="&lt;p&gt;Usually airports with approach controls will have it printed on the approach plate. Take for example the non-towered field Menominee-Marinette Twin County:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5PMci.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5PMci.png&quot; alt=&quot;KMNM Approach Plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The approach control frequency is highlighted in the chart. This is who you receive approach clearance from. KMNM is outside of KGRB (Green Bay) airspace by a good 40 miles, but KGRB approach control is responsible for the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the short answer is: Look at the approach plate for the responsible frequency/agency for the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the other part of your question is more along the lines of &quot;If I'm shooting an IFR approach, am I required to get clearance via ATC?&quot; This I'm not 100% sure about but I would guess that the answer is &quot;yes&quot; since you don't want to interfere with traffic shooting real approaches. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/aim_basic_chg_1_1-30-20.pdf#page=220&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Manual&lt;/a&gt; has advice for conducting practice approaches in section 4-3-21 (Page 204):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) ...Practice&#xA;  instrument approaches are considered to be instrument approaches made by either a VFR aircraft not on an IFR flight plan or an aircraft on an IFR flight plan.&#xA;  &lt;strong&gt;To achieve this and thereby enhance air safety, it is Air Traffic’s policy to provide for separation of such operations&lt;/strong&gt; at locations where approach control&#xA;  facilities are located and, as resources permit, at certain other locations served by ARTCCs or parent approach control facilities.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(Emphasis mine)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, it goes on to say...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(b) Before practicing an instrument approach, &lt;strong&gt;pilots should inform the approach control facility or the tower&lt;/strong&gt; of the type of practice approach they desire to make and how they intend to terminate it, ... &lt;br/&gt;&#xA;  (c) At airports without a tower, pilots wishing to make practice instrument approaches should notify the facility having control jurisdiction of the desired&#xA;  approach as indicated on the approach chart. &lt;br/&gt;&#xA;  (e) VFR aircraft practicing instrument approaches are not automatically authorized to execute the missed approach procedure. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But as I say in my comment, the AIM is a guideline, not a rule and I don't think there is anybody stopping somebody from doing an instrument approach without controller notification, however because ATC isn't providing traffic separation at that point, it could be considered negligent of the pilot to not request ATC clearance. Besides, a good portion of conducting practice approaches is talking to ATC.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="14661" LastEditDate="2020-06-06T16:08:18.307" LastActivityDate="2020-06-06T16:08:18.307" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="27234" PostTypeId="1" AcceptedAnswerId="27602" CreationDate="2016-04-27T19:57:21.143" Score="3" ViewCount="626" Body="&lt;p&gt;I'm working on a project that investigates Continuous Descent Approach (CDA), the procedure by which an aircraft approaches an airport for landing by descending continuously from cruise altitude with idle or near-idle thrust setting. As a Continuous Descent Operation (CDO), CDA provides operational benefits in terms of fuel burn reduction which reduces emissions as well as noise levels around airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In my project, I'm studying CDA operations during high traffic periods with the aim of developing key performance indicators (KPIs) for airports. However, I really need some expert and professional advice from pilots and air traffic controllers (ATC) on how CDA is being coordinated, managed, and conducted between pilots and ATCs. The following questions underscore my point:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;If a pair of jet aircraft is approaching an airport, is the separation distance between them smaller, the same, or larger under CDA and Non-CDA scenarios?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Just before touchdown on runway, is the aircraft's approach speed the same under CDA and Non-CDA scenarios?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In general, how many track miles could be used for approaching traffic at a major airport?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In general, is the airspeed during descent different between CDA and Non-CDA scenarios?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Just before touchdown, will the pilot utilize thrust to increase speed or will the aircraft be on its own volition, under CDA and Non-CDA scenarios?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="14676" LastEditorUserId="5517" LastEditDate="2016-06-17T12:30:51.550" LastActivityDate="2016-06-17T12:30:51.550" Title="Is the separation distance between two aircraft approaching an airport the same under CDA and Non-CDA scenario?" Tags="&lt;air-traffic-control&gt;&lt;aircraft-performance&gt;&lt;airport&gt;&lt;approach&gt;&lt;descent&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27235" PostTypeId="2" ParentId="27219" CreationDate="2016-04-27T21:14:52.417" Score="12" Body="&lt;p&gt;Please let me assume that you wonder about control surface effectiveness rather than their efficiency. Both are closely related, but I prefer to address their effectiveness - doing what the pilot demands them to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aerodynamic forces are proportional to the dynamic pressure $q$ of the flow, which is density times velocity squared, as in&#xA;$$q = \frac{\rho}{2}\cdot v^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To create the same amount of lift at a higher altitude, the airplane has to fly faster, so in effect the forces can stay the same. Only the true air speed will be different, which helps to get where you want faster. The control surface effectivity remains unchanged.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we dig a little deeper, the atmosphere cools down with increasing altitude until you reach the &lt;a href=&quot;https://aviation.stackexchange.com/questions/23318/what-is-tropopause-height-and-how-is-it-determined&quot;&gt;Tropopause&lt;/a&gt;. This cooling makes the engines &lt;a href=&quot;https://aviation.stackexchange.com/questions/1609/why-do-jet-engines-get-better-fuel-efficiency-at-high-altitudes/4983?s=1%7C0.1067#4983&quot;&gt;more efficient&lt;/a&gt; but also &lt;a href=&quot;https://aviation.stackexchange.com/questions/24641/drag-as-a-function-of-altitude/24644#24644&quot;&gt;reduces the Reynolds number&lt;/a&gt; of the flow around the aircraft. A lower Reynolds number translates into a thicker boundary layer, which will reduce the effectiveness of control surfaces a tiny bit and will reduce the range of their best effectivity. But this effect is so small that it has no practical consequence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airliners fly at transsonic speeds at altitude, so now sonic effects become more pronounced. For the control surfaces this means that they will &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight/5004?s=1%7C0.0930#5004&quot;&gt;lose their effectiveness at higher deflection angles&lt;/a&gt;. For small corrections all is very similar to low level, slow flight, but if you need full deflections the control surfaces are indeed less effective at altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another effect will be rather more pronounced, and this is aerodynamic damping. Damping is the tendency of a system to create additional forces from movements which run against this movement. Take a wing: If the aircraft rolls, the wingtips will move up on one side and down on the other. Both movements will add a small angle of attack, lowering the total angle of attack on the up moving tip and increasing it on the down moving tip. Both tips will see a change in lift which will counteract the rolling motion. If the rolling speed is $\omega_x$, the resulting change in angle of attack $\alpha$ at a wing station $y$ is&#xA;$$\Delta\alpha = arctan \left(\frac{\omega_x \cdot y}{v}\right)$$&#xA;As you can see, the flight speed is in the denominator, so a higher flight speed will create a smaller angle change for the same roll rate. The same holds true for the other axes of movement, and in consequence the &lt;a href=&quot;https://aviation.stackexchange.com/questions/5131/when-might-a-pilot-hand-fly-a-jet-at-cruise-altitudes-and-is-it-difficult/5132?s=3%7C0.0991#5132&quot;&gt;higher-flying aircraft needs either more pilot attention&lt;/a&gt; or an artificial damper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess it is the lower damping which made you think that the control surfaces are less effective. They aren't.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-04-28T07:14:22.053" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27236" PostTypeId="1" CreationDate="2016-04-27T22:24:59.613" Score="9" ViewCount="775" Body="&lt;p&gt;The AFM for DA40 states in 4A.3.9 CRUISE checklist:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Electrical fuel pump . . . . . . . . . . . . . . . . . . . ON at high&#xA;  altitudes&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;CAUTION Operation at high altitudes with the electrical fuel&#xA;  pump OFF may cause vapor bubbles, resulting in intermittent low fuel&#xA;  pressure indications, sometimes followed by high fuel flow&#xA;  indications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I (sort of) understand the reason for needing to compensate for lower ambient pressure with a mechanical fuel pump, but the problem is I can't find a clear reference to what is considered &quot;high altitudes&quot; for this purpose? It has a demonstrated operating limit of FL164, so we're obviously not talking crazy high.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it more of a &quot;if you experience these symptoms, try turning on the fuel pump&quot; type of caution? Or is there some specific altitude above which the pump should always be on?&lt;/p&gt;&#xA;" OwnerUserId="9012" LastEditorUserId="1696" LastEditDate="2016-06-14T16:42:08.943" LastActivityDate="2016-06-14T16:42:08.943" Title="What is considered &quot;high altitude&quot;?" Tags="&lt;high-altitude&gt;&lt;diamond-da40&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27237" PostTypeId="2" ParentId="27164" CreationDate="2016-04-27T22:27:42.590" Score="4" Body="&lt;p&gt;&quot;Working down&quot; conserves battery power, as the other answers suggest. But it is also better for endurance to descend, simply because the flight Reynolds number will be higher, and the viscous drag lower.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/24641/drag-as-a-function-of-altitude/24644#24644&quot;&gt;this answer&lt;/a&gt; for an explanation how the physics behind this works.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See &lt;a href=&quot;https://aviation.stackexchange.com/questions/3610/how-are-the-glide-polar-and-l-d-ratio-charts-related&quot;&gt;this answer&lt;/a&gt; for the Reynolds number effect on a glider. Here the same aircraft is plotted at the same altitude, but with different wing loadings, so all typical speeds increase with wing loading, and so does the Reynolds number. You will see that L/D slightly increases with Reynolds number.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the optimum polar point for minimum energy loss of propeller-driven aircraft is at a high lift coefficient $c_{L_{opt}}$, and this lift coefficient goes up with the wing's aspect ratio $AR$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$c_{L_{opt}}=\sqrt{3\cdot c_{D0}\cdot\pi\cdot AR}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At an aspect ratio of 20, this might be close to the airfoil's maximum lift coefficient, so flying slowly runs the risk of flying close to stall. Since the maximum lift coefficient goes up with the Reynolds number (after all, the viscous effects diminish and flow separation will be delayed), flying at a low altitude allows to make flying at the optimum polar point for minimum energy loss more safe or even possible. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-04-27T22:27:42.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27238" PostTypeId="1" CreationDate="2016-04-28T01:27:10.790" Score="5" ViewCount="213" Body="&lt;p&gt;If i understand correctly this is the &quot;back work ratio&quot;. I'd like to know how much % of the &quot;gross&quot; thrust is used by the turbine to drive the compressor in a typical turbofan. &lt;/p&gt;&#xA;" OwnerUserId="14683" LastActivityDate="2016-04-28T01:27:10.790" Title="Just how much power (as a percentage) is necessary to drive a compressor in a jet engine?" Tags="&lt;engine&gt;&lt;jet&gt;&lt;turbofan&gt;&lt;efficiency&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2017-08-24T23:42:26.603" ContentLicense="CC BY-SA 3.0" />
  <row Id="27239" PostTypeId="2" ParentId="27214" CreationDate="2016-04-28T01:40:36.603" Score="3" Body="&lt;p&gt;I'll use the B757 as an example, on it you would not divert due to temperature control issues. In fact the &lt;a href=&quot;http://fsims.faa.gov/wdocs/mmel/b-757%20rev30.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Master Minimum Equipment List&lt;/a&gt; items 21-61-1 and 21-61-2 give permission to dispatch the aircraft with inoperative zone temperature control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.737ng.co.uk/757%20QRH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Quick Reference Handbook (PDF)&lt;/a&gt; for the 757 gives the following instructions for failure of zone temperature control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0GaXh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0GaXh.jpg&quot; alt=&quot;flight deck checklist&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XmcNH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XmcNH.jpg&quot; alt=&quot;Cabin checklist&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I also think most airlines and crew think passengers would rather get to where they are going than being comfortable. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the emergency landing, aircraft can and do divert all the time without declaring an emergency (Mayday) or urgency (Pan-Pan). So worse case the crew would choose to divert to a suitable airport.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-04-28T01:40:36.603" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27241" PostTypeId="2" ParentId="23947" CreationDate="2016-04-28T05:40:02.397" Score="5" Body="&lt;p&gt;The precise truth cannot be known without consulting the authors of the report.  However, assuming it was not a typo, there are several contributing factors that may lead to this result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Primarily, aviation is a very conservative business, and every opportunity to mitigate risk will be taken.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this instance, not only did the aircraft lose a tire, the tire also damaged the hydraulic &quot;A&quot; line, and the flaps.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main issue to address was the tires themselves, but it was noted that the tire blowout appeared to occur at &quot;&lt;strong&gt;rotation&lt;/strong&gt;&quot;, which puts the greatest stress on the main gear tires.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the airplane may be &lt;em&gt;about&lt;/em&gt; to take wing and unload the landing gear, the moment the aircraft's nose rotates up is the moment of peak main gear loading.  The weight of the aircraft is no longer supported by the nose gear, and not yet supported by the wings.  The elevator pushes the tail and empennage &lt;em&gt;downward&lt;/em&gt; in order to raise the nose, which further burdens the main gear.  And during takeoff, the aircraft flaps will be lowered to aid in generating more lift while still at low air speeds, &lt;em&gt;BUT&lt;/em&gt;, lowering the flaps aerodynamically causes a nose-down &quot;&lt;strong&gt;moment&lt;/strong&gt;&quot;, which makes the elevator's job that much harder, and that additional force is also transferred to the main gear at the moment of &quot;rotation&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple ways to help alleviate the burden on the main gear are to not drop flaps as much, and to &quot;rotate&quot; more gradually.  Also, since flaps were damaged in the tire incident, having your flaps tucked up higher puts them less in harm's way of a possible exploding tire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why that directive in Malta?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the link below, the main runway at &lt;strong&gt;Malta Luqa Airport&lt;/strong&gt; is 11627 feet long (3544m), which is fairly long as runways go, so an aircraft can take its time getting airborne if necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skyvector.com/airport/LMML/Malta-Luqa-Airport&quot; rel=&quot;noreferrer&quot;&gt;Malta Luqa Airport charts, at SkyVector&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's not the longest runway around, but it's longer than necessary for most commercial aircraft, especially at sea level.  Malta is also a very flat place, with its highest point only 253m above the Mediterranean. (830 feet)  This makes it a reasonable place to use a procedure that would result in a longer take-off roll and more gradual climb (from the less-deployed flaps.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So there are reasons it would possibly be more doable there than at some other airports.  However, I think the dominant factor is this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Boeing 737-33A&lt;/strong&gt;, registration &lt;strong&gt;9H-ADH&lt;/strong&gt;, is a Maltese registration (as indicated by the &lt;strong&gt;9H&lt;/strong&gt;, and the aircraft belonged to &lt;strong&gt;Air Malta&lt;/strong&gt; at the time of the incident.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I used the past-tense, since the current ledger of aircraft registered in Malta does not include that aircraft.  In fact it was transferred (sold?) to Air New Zealand in 2008, and is now in Bahrain, to the best of my knowledge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airfleets.net/ficheapp/plane-b737-27459.htm&quot; rel=&quot;noreferrer&quot;&gt;737 s/n 27459 registration history&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While I do suspect there is more to the story details than we are privy to in that one publication, it's my opinion, as a certified aircraft mechanic and persistent internet sleuth, that the change in practice was made as a matter internal to Air Malta operations at their home airfield.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bonus: A photo of the actual aircraft, after the incident in question, sitting cordoned off, on the ramp at Glasgow International Airport (&lt;strong&gt;GLA&lt;/strong&gt;).  Click the link above the pic for a little more info, and additional resources.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.jetphotos.net/viewphoto.php?id=352716&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737, registration 9H-ADH&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZiYnV.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZiYnV.jpg&quot; alt=&quot;Boeing 737-33A - 9H-ADH&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cheers!&lt;/p&gt;&#xA;" OwnerUserId="14575" LastActivityDate="2016-04-28T05:40:02.397" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27242" PostTypeId="2" ParentId="27236" CreationDate="2016-04-28T07:05:28.040" Score="7" Body="&lt;p&gt;It seems I've asked a question that has no answer. From the explanation below provided by a Diamond Aircraft representative, it is clarified that the intent of the AFM's caution is not to always run the electric fuel pump at high altitude, but to use it as needed to clear the symptoms - which are more likely to occur as altitude increases.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The IO 360 with the Precision Fuel Injection System does not have a&#xA;  vapor separation and return line to the tank(s). Vapor in the fuel&#xA;  system will travel through the fuel system including flow and pressure&#xA;  transducers, into the injection system. Vapor can form under higher&#xA;  ambient temperatures and low ambient pressures. Fuel gravity fed&#xA;  through the system (electric pump off) from the tanks is “lifted” by&#xA;  the mechanical pump. The suction of the mechanical pump can cause some&#xA;  cavitations (vapor formation), especially as the fuel flows through&#xA;  resistances such as elbow fittings. Vapor bubbles will cause momentary&#xA;  low pressure indications and may also cause momentary erratic or high&#xA;  flow readings as the flow transducer turbine spools up with the loss&#xA;  of fluid resistance. These momentary occurrences can be suppressed&#xA;  with the electric pump. The electric pump activation increases system&#xA;  pressure to compress or return to liquid, the formed fuel vapor&#xA;  bubbles.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The intention of the steps for electrical pump selection, above each&#xA;  of the Cautions in the AFM &lt;em&gt;is not for continuous operation of the&#xA;  pump&lt;/em&gt;, as this could potentially mask a defective mechanical pump and&#xA;  eliminate the redundancy of the fuel delivery system. If the abnormal&#xA;  fuel pressure or flow indications do not stabilize with the electric&#xA;  pump on, emergency procedures and maintenance action may be required.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9012" LastActivityDate="2016-04-28T07:05:28.040" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27243" PostTypeId="2" ParentId="11984" CreationDate="2016-04-28T07:46:32.307" Score="2" Body="&lt;p&gt;Since the question is about &lt;em&gt;how&lt;/em&gt; to find them, and not actually asking for a listing of them, I'll answer that one option would be to locate a flight school (ideally one operating near KATL like &lt;a href=&quot;http://aeroatlanta.com/&quot; rel=&quot;nofollow&quot;&gt;Aero Atlanta&lt;/a&gt; at DeKalb-Peachtree) and pay for a one hour ground school lesson specifically on how to read KATL's Visual and Instrument approaches (the flights could be on either depending on what's happening with weather and ATC.) A CFI would be able to help you identify which procedures cross low over your area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The downside is it will cost you (probably in the neighborhood of $50) but you'll get a really interesting introduction to airport procedures. And may even lead to a discovery flight!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also find out that none of the arrival procedures involve low routes over you and ATC was vectoring traffic into unusual areas to create space for a situation at the field. Within Class B airspace, all aircraft are under positive radar control by ATC, meaning they can pretty much send any aircraft anywhere they want if the situation warrants and the pilots are able to comply. Still for noise abatement reasons they usually wouldn't have large jets flying low unless they were on an approach.&lt;/p&gt;&#xA;" OwnerUserId="9012" LastActivityDate="2016-04-28T07:46:32.307" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27244" PostTypeId="2" ParentId="26084" CreationDate="2016-04-28T08:19:26.353" Score="2" Body="&lt;p&gt;One factor I haven't seen mentioned is that many GA pilots like to fly with excessive reserve fuel (far beyond FAA requirements) as a safety margin. In addition some operators keep the tanks full in order to avoid condensation* in aircraft which tend to sit for long periods. For those reasons it is not unusual for a GA flight to carry significantly more fuel than it needs on any given leg. If you're going to carry a full tank anyway, it will certainly be more efficient to make the trip without stopping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airlines are obviously critical of waste related to carrying excess fuel and have policies in place intended to ensure that no more than the minimum required fuel is carried on any leg. The closer that works out to being true, the more relevant this question becomes. But knowing my share of airline pilots, I also find that the more disgruntled they are, the less inclined they are to pinch pennies for the boss. i.e. The benefits gained from flying shorter legs will likely be partially negated by carrying excess fuel anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sub&gt;* Regardless of whether the condensation theory has merit, storing the tanks full is commonly taught as good practice.&lt;/sub&gt;&lt;/p&gt;&#xA;" OwnerUserId="9012" LastActivityDate="2016-04-28T08:19:26.353" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27245" PostTypeId="2" ParentId="27210" CreationDate="2016-04-28T09:39:05.887" Score="3" Body="&lt;p&gt;What you need would be named &quot;ICAO 1/500,000 map&quot;, this is a VFR map with airspace class, based on a &lt;a href=&quot;https://en.wikipedia.org/wiki/Lambert_conformal_conic_projection&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lambert conformal conic projection&lt;/a&gt;. Example in the US (1/250,000):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/4DZ42.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4DZ42.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best I can find online is SkyVector, but you said it's not sufficient for you needs:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c3M6R.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c3M6R.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;By searching carefully you may find things like that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ISwTu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ISwTu.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EdN4u.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EdN4u.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(source: &lt;a href=&quot;http://www.lib.utexas.edu/maps/onc/&quot; rel=&quot;nofollow noreferrer&quot;&gt;University of Texas&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But these are 1/1,000,000th very old maps from US DoD.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An alternative would be to use the online &lt;a href=&quot;http://gis.icao.int/icaoviewer/&quot; rel=&quot;nofollow noreferrer&quot;&gt;GIS viewer from ICAO&lt;/a&gt;, selecting carefully layers and data to display, my trial at that:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LUBPV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LUBPV.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It must be improved to suit your needs, but I don't expect it to be better than SkyVector. By clicking on a location, you can display all the information about relevant areas (description, limits, etc).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;For enroute, &lt;a href=&quot;http://www.eurocontrol.int/articles/eurocontrol-regional-charts-erc&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurocontrol&lt;/a&gt; provide two maps:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/content/documents/nm/cartography/erc04h-31mar2016.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;High altitude&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.eurocontrol.int/sites/default/files/content/documents/nm/cartography/erc05l-31mar2016.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Low altitude&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Good for intersection points and routes.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;On the airport plates side, the &lt;a href=&quot;http://ssd.dhmi.gov.tr/ANSLogin.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIP for Turkey&lt;/a&gt; is not in public access, but several sites provide plates, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.thyva.com/charts&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turkish Virtual Airlines&lt;/a&gt; (static)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.rocketroute.com/weather.php?icao=ltac&quot; rel=&quot;nofollow noreferrer&quot;&gt;RocketRoute&lt;/a&gt; (interactive)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://airportnavfinder.com/airport/LTBA/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AirportNavFinder&lt;/a&gt; provides link to other sites like SkyVector.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ivaotr.org/&quot; rel=&quot;nofollow noreferrer&quot;&gt;IVAO Turkey&lt;/a&gt; could be a good point of contact to discuss local documentation. They have a section Charts accessible to registered users.  - &lt;a href=&quot;http://www.turvacc.org/pilots/air/ltba-istanbul-ataturk-int-l.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;VACC turkey&lt;/a&gt; is another virtual network.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you can provide additional requirements, me or someone else may provide better material.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastActivityDate="2016-04-28T09:39:05.887" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27247" PostTypeId="1" AcceptedAnswerId="27250" CreationDate="2016-04-28T11:30:11.973" Score="3" ViewCount="198" Body="&lt;p&gt;Can an auto-gyro apply for commercial purposes? Utility in remote areas, Alaska for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What license is needed (airworthiness, etc.)? How much does it cost approximately?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I build my own Auto-gyro and license it to this purpose? Applying for the required FAA license surely will improve the design's safety.&lt;/p&gt;&#xA;" OwnerUserId="14675" LastEditorUserId="5517" LastEditDate="2016-04-28T13:30:10.497" LastActivityDate="2016-04-28T15:24:19.670" Title="Can I apply for a commercial-utility licence for an auto-gyro?" Tags="&lt;faa-regulations&gt;&lt;commercial-aviation&gt;&lt;commercial-operations&gt;&lt;pilot-certification&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27249" PostTypeId="1" AcceptedAnswerId="27257" CreationDate="2016-04-28T12:57:56.203" Score="5" ViewCount="401" Body="&lt;p&gt;I was wondering why the fuselage of a passenger airplane is not built along with the nose? It might be difficult to build fuselage and wings together as one unit, but nose is a small part. Then why is it made separately? &lt;/p&gt;&#xA;" OwnerUserId="14627" LastEditorUserId="19" LastEditDate="2017-05-15T08:11:04.823" LastActivityDate="2017-05-15T08:11:04.823" Title="Why are passenger and cargo airplane noses manufactured separately from fuselages and then put together?" Tags="&lt;fuselage&gt;&lt;aircraft-manufacturer&gt;&lt;nose&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27250" PostTypeId="2" ParentId="27247" CreationDate="2016-04-28T13:42:05.253" Score="4" Body="&lt;p&gt;Really this is a moot point...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.319&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.319&lt;/a&gt; (a) states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) No person may operate an aircraft that has an experimental certificate—&lt;br/&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;(1) For other than the purpose for which the certificate was issued; or&lt;br/&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;(2) &lt;strong&gt;Carrying persons or property for compensation or hire&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And again (e) states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(e) &lt;strong&gt;No person may operate an aircraft that is issued an experimental certificate under§ 21.191(i) of this chapter for compensation or hire&lt;/strong&gt;, except a person may operate an aircraft issued an experimental certificate under § 21.191(i)(1) for compensation or hire to—&lt;br/&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;(1) Tow a glider that is a light-sport aircraft or unpowered ultralight vehicle in accordance with§ 91.309; or &lt;br/&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;(2) Conduct flight training in an aircraft which that person provides prior to January 31, 2010.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/21.191#i_1&quot; rel=&quot;nofollow&quot;&gt;21.191 (i)&lt;/a&gt; is in reference to operating light-sport aircraft and how it obtains an experimental certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are very few auto-gyros that are factory built and certified, and none that I can find that are currently being built. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anything you build in your home (home-built) needs to pass certain FAA inspections before it is issued an airworthiness certificate and/or experimental certificate. All home-builts are experimental since they are not built under the manufacturers quality control system. Either way, the FAA certifies that you build it to a safe standard and a standard in which the manufacturer intended it to fly. Being used for a commercial purpose, even if that were possible (which it is not) would not change the certification process for that aircraft. It would not require you to abide by any different rules or build standards. That is implying that personal aircraft would be built to a lower safety standard than commercial ones, which isn't the case.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="62" LastEditDate="2016-04-28T15:24:19.670" LastActivityDate="2016-04-28T15:24:19.670" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27251" PostTypeId="1" AcceptedAnswerId="27260" CreationDate="2016-04-28T13:53:55.203" Score="5" ViewCount="932" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/c3M6R.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/c3M6R.jpg&quot; alt=&quot;screenshot from SkyVector - Ankara/Turkey&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By looking at the dashed blue lines overlay with thick faded blue lines, can we say these are Class D airspace and Class E airspace above 1200' AGL?&lt;/p&gt;&#xA;" OwnerUserId="14589" LastActivityDate="2016-04-29T15:39:20.160" Title="What does dashed blue lines overlay with thick faded blue lines mean in an aeronautical-chart?" Tags="&lt;airspace&gt;&lt;aeronautical-charts&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27252" PostTypeId="1" CreationDate="2016-04-28T15:18:14.413" Score="9" ViewCount="2009" Body="&lt;p&gt;The Federal Aviation Administration (FAA) made Runway Incursion Avoidance a special emphasis area and added it as a required task in several of the Practical Test Standards (PTS) documents. All the PTS documents have a bullet item that reads something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Distinct challenges and requirements during taxi operations not found in other phases of flight operations.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have reviewed the applicable sections of the &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/media/pdf/PHAK%20-%20Appendix%201%20-%20April%202012.pdf&quot;&gt;Pilot's Handbook of Aeronautical Knowledge&lt;/a&gt; and &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2091-73B.pdf&quot;&gt;AC 91-73B&lt;/a&gt;, but I haven't found a concrete answer on what exactly these challenges are. If an examiner asked me to explain these challenges I'd do my best, and I'm sure I could come up with some good arguments for my thoughts, but I like to know what the FAA is looking for when they ask a question and this one doesn't seem to have an exact reference.&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2016-05-14T00:40:57.183" Title="What distinct challenges are faced in taxi operations that aren't found in other phases of flight?" Tags="&lt;runway-incursion&gt;" AnswerCount="3" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27253" PostTypeId="1" CreationDate="2016-04-28T15:56:32.567" Score="1" ViewCount="61" Body="&lt;p&gt;The solar impulse has a massive wing span, greater than a jumbo jets. Would it not be possible to have a biplane design to shorten the wingspan(making it more practical and maneuverable)and have the wings offset so that they both capture the sun?&lt;/p&gt;&#xA;" OwnerUserId="14699" LastEditorUserId="14699" LastEditDate="2016-04-28T18:01:05.857" LastActivityDate="2016-04-28T18:01:05.857" Title="Solar biplane possibilty?" Tags="&lt;aerodynamics&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2016-04-28T17:36:04.483" ContentLicense="CC BY-SA 3.0" />
  <row Id="27254" PostTypeId="1" CreationDate="2016-04-28T16:02:47.747" Score="6" ViewCount="230" Body="&lt;p&gt;What are the chances of rotor failure? What percentage of crashes are related to a malfunction of the rotor head? &lt;/p&gt;&#xA;" OwnerUserId="14675" LastActivityDate="2016-10-01T21:25:51.043" Title="what is the statistical risk of head rotor failure?" Tags="&lt;security&gt;&lt;rotorcraft&gt;&lt;aircraft-failure&gt;&lt;rotor-head&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27256" PostTypeId="1" AcceptedAnswerId="27302" CreationDate="2016-04-28T16:20:16.077" Score="9" ViewCount="1196" Body="&lt;p&gt;In the USA, is there a way to find locations of VHF transmitters that are used for air traffic communication, and the frequencies they transmit/receive on? There are some places (Northern Bay Area, CA) where I fly where I have good signal/communication with a Terminal Radar facility, but have trouble contacting area approach in the same area - especially when low (&amp;lt;2000ft AGL). The area is hilly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interesting in seeing range and altitude support for a given frequency (in a given area).&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2017-02-24T22:15:28.787" LastActivityDate="2020-01-21T19:18:10.090" Title="How can I find the location and coverage of aviation VHF transmitters?" Tags="&lt;usa&gt;&lt;radio-communications&gt;&lt;radio&gt;" AnswerCount="2" CommentCount="13" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27257" PostTypeId="2" ParentId="27249" CreationDate="2016-04-28T17:21:46.153" Score="7" Body="&lt;p&gt;A radome, or nose cone, is essentially a structural cover serving a different purpose than the fuselage. These are made separate because they a special material invisible to the radar mounted beneath them. They are different shapes or sizes depending on the customer specific component they cover (radar antennas) and can be easily removed or replaced. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The radome serves two essential purposes. 1) It covers electronic equipment mounted to the forward bulkhead of the fuselage to protect it from weather, or from view. 2) It acts as an aerodynamic cover for the leading edge of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Nose_cone&quot; rel=&quot;noreferrer&quot;&gt;https://en.wikipedia.org/wiki/Nose_cone&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2127" LastActivityDate="2016-04-28T17:21:46.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27258" PostTypeId="2" ParentId="27226" CreationDate="2016-04-28T17:32:15.470" Score="6" Body="&lt;p&gt;I fly out of a controlled satellite class D (&lt;a href=&quot;http://airnav.com/airport/KLOU&quot; rel=&quot;nofollow noreferrer&quot;&gt;KLOU, Bowman Field&lt;/a&gt;) below a class C (&lt;a href=&quot;http://airnav.com/airport/KSDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;KSDF, Louisville International&lt;/a&gt;) so I'm fairly familiar with this scenario, at least in the way that it's handled there. The short story - in my experience - is that Approach only cares about you having the numbers or ATIS for the airport where you'll actually land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First the theory. The &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC orders&lt;/a&gt; say:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;7−1−3. APPROACH CONTROL SERVICE FOR VFR ARRIVING AIRCRAFT&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Issue the following where procedures have been  established for&#xA;  arriving VFR aircraft to contact approach control for landing&#xA;  information:  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. Wind, runway, and altimeter setting at the airport of intended&#xA;  landing. This information may be omitted if contained in the ATIS&#xA;  broadcast and the pilot states the appropriate ATIS code or if the&#xA;  pilot uses the phrase, “have numbers.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note the &quot;airport of intended landing&quot;, they aren't going to pester you to get the ATIS for somewhere that you aren't going to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the practice. If I'm inbound to KLOU on flight following (don't leave home without it!) then my first contact with Louisville Approach usually goes like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Me: &lt;em&gt;Louisville Approach, N12345 level at 6500&lt;/em&gt;&lt;br&gt;&#xA;  Appch: &lt;em&gt;N12345, roger, Louisville Altimeter is 2992, report when you have the weather at Bowman, information Kilo is current&lt;/em&gt;&lt;br&gt;&#xA;  Me: &lt;em&gt;N12345 has Kilo at Bowman&lt;/em&gt;&lt;br&gt;&#xA;  Appch: &lt;em&gt;N12345, roger [and further instructions as needed]&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As a controlled field, Bowman has ATIS, not &quot;the numbers&quot; but I've had more or less the same exchange at other places. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think that &lt;a href=&quot;https://aviation.stackexchange.com/questions/27226/what-are-approach-control-weather-information-expectations-for-flights-to-satell#comment66875_27226&quot;&gt;Ron's comment&lt;/a&gt; about information is useful here: when I'm inbound I usually have both the KSDF and KLOU ATIS anyway, just in case. Also notice how the KSDF controller helps me: the KLOU ATIS could have changed from Kilo to Lima between the time I got it and the time I called Approach. By telling me that Kilo is current, the controller is effectively telling me if I have to go and get the ATIS again or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for just passing through class C, the very few times I've done that ATC has simply given me the local altimeter setting and that's it. I'm not landing, so they don't seem to care if I have the ATIS or not.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-04-28T17:32:15.470" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27259" PostTypeId="2" ParentId="1573" CreationDate="2016-04-28T18:19:03.373" Score="3" Body="&lt;p&gt;I passed my checkride on April 19th and was told by both the DPE and my instructor that typical wait times to receive the permanent certificate in the mail are around 90 days.  The DPE told me to mark the 120 expiration date of the temporary certificate on my calendar and that I should call the local FSDO if I had not received the permanent one in the mail and it was approaching two weeks from the expiration of the temporary.  The FSDO can grant 30 day extensions to your temporary certificate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just keep this in mind: It's is very important not to let the temporary expire since that temporary certificate &quot;supersedes&quot; all previous certificates.  This means you have NOTHING if a temporary Private Pilot certificate has expired and you have not yet received the permanent one.  Even your original Student Pilot certificate is no longer in effect, since it was superseded when you were issued your temporary private certificate; therefore you won't even be able to fly solo anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As long as you contact your local FSDO within a couple weeks prior to the temporary certificate's expiration, you should have no problems.&lt;/p&gt;&#xA;" OwnerUserId="14701" LastActivityDate="2016-04-28T18:19:03.373" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27260" PostTypeId="2" ParentId="27251" CreationDate="2016-04-28T19:20:00.923" Score="7" Body="&lt;p&gt;&lt;strong&gt;Overall: Turkey system may be specific&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turkey is not integrated in the Single European Sky. The harmonization and simplification of airspace classification going on in many European countries is not applicable to Turkey, so we are in a kind of specific case which requires more research effort to understand it. See this &lt;a href=&quot;https://www.eurocontrol.int/sites/default/files/content/documents/official-documents/reports/2013-lssip-turkey.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurocontrol report&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the documentation I happen to read, the Turkish airspace system is seemingly as efficient as another and, for instance, is more efficient in releasing military areas (SUA) to civil use when possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wasn't able to find any description. If you can register to the &lt;a href=&quot;http://ssd.dhmi.gov.tr/ANSLogin.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;Turkey AIP&lt;/a&gt;, you should have access to the relevant data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional information from ICAO GIS Viewer&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same area than the one in the question in the &lt;a href=&quot;http://gis.icao.int/icaoviewer/&quot; rel=&quot;nofollow noreferrer&quot;&gt;ICAO viewer&lt;/a&gt;. I have selected different layers (a bit of learning would be needed to understand all of them), and highlighted data for three areas:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/288pp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/288pp.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I selected only the lower space, else the viewer display is really cluttered because the developers haven't done a great job in managing label locations. The areas are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Yellow: ANKARA &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_Control_Center&quot; rel=&quot;nofollow noreferrer&quot;&gt;ACC&lt;/a&gt; SCTR 8 LOWER. GND to FL325.&lt;/li&gt;&#xA;&lt;li&gt;Blue:  ESENBOGA &lt;a href=&quot;https://en.wikipedia.org/wiki/Control_zone&quot; rel=&quot;nofollow noreferrer&quot;&gt;CTLZ&lt;/a&gt;. SFC to 4,500 AMSL&lt;/li&gt;&#xA;&lt;li&gt;Green: AKINCI CTLZ. SFC to 12,000 AMSL&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You can click on an area and a list of descriptions is displayed. You can browse this list with the arrows on the popup title bar (multiple areas may be relevant for the point you clicked). For AKINCI CTLZ:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/M7axu.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/M7axu.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which class of airspace are they? Which rules are associated with them? I've really no idea and the legend in the viewer doesn't help:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/yDQmj.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/yDQmj.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Special use airspace (SUA)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think it's still reasonable to interpret for non-professional purposes the area names this way (LT being the ICAO prefix for Turkey):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;LTD: Danger (e.g. LDT-20)&lt;/li&gt;&#xA;&lt;li&gt;LTR: Restricted or Regulated (e.g. LTR-30)&lt;/li&gt;&#xA;&lt;li&gt;LTP: Prohibited (e.g. LTP-0097)&lt;/li&gt;&#xA;&lt;li&gt;LTM: Military (e.g. LTM-LTANKZ1).&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So these are &lt;a href=&quot;https://en.wikipedia.org/wiki/Special_use_airspace&quot; rel=&quot;nofollow noreferrer&quot;&gt;SUA&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Documents that may be interesting&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.ivaotr.org/downloads/documents/other/APOM-TR%20Rev.4.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;ATC Prosedür ve Operasyonları Kılavuzu&lt;/a&gt; from IVAO Turkey.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Get additional help&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also want to look at &lt;a href=&quot;http://www.pprune.org/&quot; rel=&quot;nofollow noreferrer&quot;&gt;PPRuNE&lt;/a&gt; which is a discussion board for pilots. You'll find pilots flying in/to Turkey, and they may provide you more information.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-04-29T15:39:20.160" LastActivityDate="2016-04-29T15:39:20.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27261" PostTypeId="2" ParentId="27252" CreationDate="2016-04-28T20:25:57.157" Score="0" Body="&lt;p&gt;Challenges: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Your airplane is on ground, so the physics of ground play role. Slipping, skidding, stopping, decelerating, pushback etc. &lt;/li&gt;&#xA;&lt;li&gt;Visual outlook responsibility is both the pilot's and the tower's and any other traffic's.&lt;/li&gt;&#xA;&lt;li&gt;A fuel truck or passenger bus or a follow me car can hit you any time. &lt;/li&gt;&#xA;&lt;li&gt;Navigating on the airport can be stressful for a first comer pilot, especially if it's a crowded airport. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Whereas in air, most of the events are foreseen, and the autopilot handles most of the detailed tasks and creates the situational awareness to give time for the pilot to think carefully.&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2016-04-28T20:25:57.157" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27262" PostTypeId="2" ParentId="25676" CreationDate="2016-04-28T20:53:54.907" Score="3" Body="&lt;p&gt;I also want to mention these advantages (in addition to the lower operational cost):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Easy to fly and enjoy the flying experience.&lt;/li&gt;&#xA;&lt;li&gt;Because it is in constant autorotation it can't stall.&lt;/li&gt;&#xA;&lt;li&gt;It's simpler than a helicopter or plane&lt;/li&gt;&#xA;&lt;li&gt;Because it's simpler and can't stall: With a proper design It can be safer than a helicopter or plane.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Mix that and you find the perfect recipe for sport/pleasure flying for people that have been dreaming of flying. Also this is the foundation of the bad safety reputation (with is not the fault of autogyros) as amateurs are building and flying this aircraft without the proper preparation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;With a prerotator and rotor pitch control it can do jump takeoffs, taking off vertically.&lt;/li&gt;&#xA;&lt;li&gt;It can not hover but it can land within a very short distance (practically none)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In conclusion, &lt;strong&gt;private usage&lt;/strong&gt; is the perfect application for Autogyros.&lt;/p&gt;&#xA;" OwnerUserId="14675" LastEditorUserId="14675" LastEditDate="2016-04-28T22:08:39.113" LastActivityDate="2016-04-28T22:08:39.113" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27263" PostTypeId="1" AcceptedAnswerId="27376" CreationDate="2016-04-28T22:30:28.387" Score="17" ViewCount="8603" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/questions/21464/why-do-jet-engines-take-a-long-time-to-throttle-down&quot;&gt;my related question&lt;/a&gt;, it seems that an engine suddenly shut off would suffer from dangerous differential cooling from the airflow. This differential cooling would cause the engine to warp.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So now I'm wondering about a jet engine that suddenly enters rain. &lt;strong&gt;Wouldn't this initially cause severe differential cooling and thus warping, maybe even cracking?&lt;/strong&gt; (P.S. would the same thing happen from entering a thick, dark cloud?)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How does the engine handle a huge amount of sudden rain ingestion? To me it seems like the sudden cooling on one side of the engine would cause thermal contraction, causing all sorts of problems.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; There seems to be a lot of comments about rain certification for engines and the fact that jets fly through rain all the time with no problem. I'm not questioning any of that. What I want to know is, how a jet engine handles &lt;strong&gt;the differential cooling caused by rain without warping or cracking?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-05-05T17:40:02.060" Title="How does a jet engine handle suddenly entering a lot of rain?" Tags="&lt;jet-engine&gt;&lt;weather&gt;" AnswerCount="2" CommentCount="19" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27264" PostTypeId="2" ParentId="27251" CreationDate="2016-04-29T00:09:06.447" Score="0" Body="&lt;p&gt;The numbers are probably in hundreds of meters. So 120/SFC would be surface to 12,000 meters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Turkey does not have the kind of airspace classification that we do in the United States. The dashed blue lines probably just mean that it is controlled airspace. You can see that there are frequencies listed. So, what that means, is that you have to call on those frequencies to get clearance to enter those areas.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-04-29T00:09:06.447" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27265" PostTypeId="2" ParentId="27252" CreationDate="2016-04-29T03:50:24.750" Score="1" Body="&lt;p&gt;There are quite a few challenges:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Low visibility taxi&lt;/li&gt;&#xA;&lt;li&gt;Did I mention complex taxi routes in low visibility&lt;/li&gt;&#xA;&lt;li&gt;Hot spots (which are designed to alert pilots to possible taxi operational challenges&lt;/li&gt;&#xA;&lt;li&gt;Runway incursion&lt;/li&gt;&#xA;&lt;li&gt;Winds and the possibility of the upwind wing rising unless compensated for.&lt;/li&gt;&#xA;&lt;li&gt;Taxiing with your feet and staying on the yellow line&lt;/li&gt;&#xA;&lt;li&gt;Jet blast&lt;/li&gt;&#xA;&lt;li&gt;Taxiing on a snow covered or icy taxiway&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-04-29T03:50:24.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27267" PostTypeId="1" CreationDate="2016-04-29T06:01:21.343" Score="6" ViewCount="220" Body="&lt;p&gt;Are there any special kinds of fuels that manufacturers are considering in order to make high performance, high efficiency jet engines?&lt;/p&gt;&#xA;" OwnerUserId="14704" LastEditorUserId="1467" LastEditDate="2016-04-29T13:56:38.093" LastActivityDate="2016-04-29T16:13:15.790" Title="Is there a special kind of fuel needed to obtain high efficiency engines?" Tags="&lt;jet-engine&gt;&lt;fuel&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27268" PostTypeId="1" CreationDate="2016-04-29T06:56:07.397" Score="14" ViewCount="2548" Body="&lt;p&gt;In other words, after some training, is it possible to recovery a spin solely by relying on instruments? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If using a vacuum-pump traditional attitude indicator, I assume the answer is no, since there are limitations for its pitch and bank indication. What about an AHRS-based attitude indicator? Is it capable of matching 360° attitude changes in all directions, and catching up (without delay) with fast rolls? Can it filter out vibration well enough, so that a pilot is able to perform a spin recovery maneuver?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastEditorUserId="62" LastEditDate="2016-04-29T19:13:02.247" LastActivityDate="2020-04-06T16:30:36.657" Title="Is it possible to perform a spin recovery in IMC?" Tags="&lt;maneuver&gt;&lt;spins&gt;&lt;imc&gt;" AnswerCount="6" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27270" PostTypeId="1" AcceptedAnswerId="27283" CreationDate="2016-04-29T10:01:53.907" Score="6" ViewCount="4769" Body="&lt;p&gt;It 'appears' that in most flights the horizontal stabilizer is set for positive angle of attack. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So does this produce an 'up force' (lifting force) on tail thus making the aircraft nose-heavy? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or does the horizontal stablizer presents itself to the relative air at a different angle of attack than the wing does (which creates down force on tail)?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastActivityDate="2021-01-20T21:29:19.003" Title="What is the angle of attack of horizontal stabilizer?" Tags="&lt;nose&gt;&lt;tail&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27272" PostTypeId="2" ParentId="27268" CreationDate="2016-04-29T13:32:20.607" Score="16" Body="&lt;p&gt;Entirely possible, although it is the turn coordinator not the artificial horizon that is primary -- to determine the direction of the spin.  Nose-down elevator, rudder opposite the spin, the when spinning stops recover from the dive using airspeed &amp;amp; altimeter for pitch control &amp;amp; the turn coordinator for roll. Those instruments don't tumble.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm told that in the 1950s, spin recovery in simulated IMC was a requirement for some ratings (commercial, instrument, and/or ATP - not sure which).  Not so much now, obviously, but with a suitable airplane and appropriate instruments, it is entirely possible.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-04-29T13:32:20.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27274" PostTypeId="1" AcceptedAnswerId="27290" CreationDate="2016-04-29T15:47:49.503" Score="16" ViewCount="5566" Body="&lt;p&gt;I'm sure many helicopters also need/use Hangars frequently. How do you take them to a hangar and take them out of it without wheels?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specially when they have to be taken indoors for some maintenance work on them. Are there any special forklifts/carts used for ground handling of helicopters that do not use wheels and need to be moved without actually flying?&lt;/p&gt;&#xA;" OwnerUserId="1048" LastEditorUserId="1048" LastEditDate="2016-05-01T05:35:29.953" LastActivityDate="2016-05-01T05:35:29.953" Title="Helicopters with landing skids, no wheels; How are they taken in and out of a hangar?" Tags="&lt;helicopter&gt;&lt;landing-gear&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27275" PostTypeId="2" ParentId="27267" CreationDate="2016-04-29T15:48:13.527" Score="5" Body="&lt;p&gt;Surprisingly, it isn't a big factor in GA or commercial aviation.&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;                            Specific  Energy&#xA;                            Energy    Density&#xA;                            MJ/Kg     MJ/L&#xA;Diesel / Fuel oil           48        35.8&#xA;LPG (inc Propane / Butane)  46.4      26    &#xA;Jet fuel (Kerosene)         46        37.4&#xA;Gasoline (petrol)           46.4      34.2&#xA;HMX (Rocket Fuel)            5.7      10.8  &#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Even high-performance long-range military aircraft like the U2 and SR-71 use some variant of Kerosene with additives, their fuels are optimized for high flash point, not for energy density or for specific energy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, availability and infrastructure trump efficiency.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Energy_density&quot; rel=&quot;nofollow&quot;&gt;Wikipedia: Energy Density&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Thielert_Centurion&quot; rel=&quot;nofollow&quot;&gt;Aircraft Diesel Engine&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1289" LastEditorUserId="1289" LastEditDate="2016-04-29T16:13:15.790" LastActivityDate="2016-04-29T16:13:15.790" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27276" PostTypeId="2" ParentId="8391" CreationDate="2016-04-29T16:22:34.330" Score="1" Body="&lt;p&gt;There is some case law that states that your privacy extends up to 87.5'AGL  This was in application to a hovering 'drone'  flyovers for other purposes probably does not apply.  General flyovers of adjacent property would fall under the same rules and laws that govern manned aircraft overflight - FAA domain.  Privacy laws seem to be more narrow to hovering.  Expectation of privacy has many limitations.  eg. if the paparazzi can see you with their long range cameras, then you do not likely have much of an argument re privacy.  However if you have an 8' fence and there are no tall structures which allow a clear view, you might just have a claim - Property rights domain.&lt;/p&gt;&#xA;" OwnerUserId="14713" LastActivityDate="2016-04-29T16:22:34.330" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27278" PostTypeId="1" AcceptedAnswerId="27282" CreationDate="2016-04-29T17:43:34.500" Score="2" ViewCount="291" Body="&lt;p&gt;Why the temperature of hot gas entering the turbine is maintained  far below the adiabatic combustion temperature?&lt;/p&gt;&#xA;" OwnerUserId="14618" LastEditorUserId="19" LastEditDate="2016-07-28T13:04:54.433" LastActivityDate="2016-07-28T13:04:54.433" Title="Why is the combustion temperature in a turbojet engine kept low?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;&lt;temperature&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27279" PostTypeId="2" ParentId="27268" CreationDate="2016-04-29T17:50:50.923" Score="3" Body="&lt;p&gt;It's certainly possible, but also highly unlikely. It's possible because - ignoring thunderstorms, icing or other extreme conditions - being inside a cloud doesn't change how the aircraft handles or &lt;a href=&quot;https://aviation.stackexchange.com/q/11246/62&quot;&gt;how to recover from a spin&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real challenge would be to &lt;a href=&quot;https://aviation.stackexchange.com/q/12234/62&quot;&gt;recognize that you're in a spin&lt;/a&gt; and react quickly. &lt;a href=&quot;https://aviation.stackexchange.com/q/9764/62&quot;&gt;With no visual reference&lt;/a&gt;, the only way to know you're spinning is to deduce it from the instruments, and it could be very difficult for you to interpret them correctly and in time to prevent a crash. Even more difficult if some have toppled or become unreliable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's true that &quot;unusual attitude&quot; recovery is part of instrument training in the US (and probably most other places), but the training exercises are usually based on steep, turning climbs and descents or near stalls. I couldn't find any solid information on spin training under the hood, but personally I think it's highly unlikely that most pilots would survive, unless perhaps they have an &lt;a href=&quot;https://aviation.stackexchange.com/q/593/62&quot;&gt;airframe parachute&lt;/a&gt; and deploy it promptly. Or they break out of cloud with enough altitude - and presence of mind - to recover safely. I've never heard of an instructor spinning an aircraft with a student under the hood, although I suppose there's no specific reason not to. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, it's often &lt;a href=&quot;https://books.google.com/books?id=bGUok8wPJHIC&amp;amp;lpg=PA158&amp;amp;ots=V5_dFnedJM&amp;amp;dq=aviation%20spin%20down%20through%20clouds&amp;amp;pg=PA158#v=onepage&amp;amp;q=aviation%20spin%20down%20through%20clouds&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;mentioned&lt;/a&gt; that in the early days of aviation, spinning was used as a way to descend through a narrow hole in clouds or even directly through the clouds. It was a 'convenient' way to lose altitude quickly while staying in more or less the same place. On the other hand, I've never read a first-person account of that (maybe someone else has?) and without knowing for sure where the cloud bases are it would be extremely dangerous. But every description I've seen also says that pilots spun through the clouds before recovering in VMC, which is a different situation anyway.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-04-29T17:50:50.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27280" PostTypeId="1" AcceptedAnswerId="32924" CreationDate="2016-04-29T18:15:44.907" Score="3" ViewCount="748" Body="&lt;p&gt;Are there official definitions of air traffic corridor pathing? Specifically European &amp;amp; Mediterranean routes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm working on an application that needs this input data to perform an analysis. I and others in my company have been unable to find anything, and I really don't want to have to derive something approximating it myself if I don't have to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Since what I'm asking for doesn't seem to be very clear I'll try a different way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When an commercial jet starts a flight from one airport to another. I assume it had a generally predetermined path (or options of paths). These are not straight shortest path between two points on an ellipsoid so the data at &lt;a href=&quot;http://openflights.org/data.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;OpenFlights.org&lt;/a&gt; isn't helpful, as it is not accurate enough. Obviously though no one can fully predict exactly where an aircraft will be in the future because that changes in respect to many different unknown variables, but I need something more like &lt;a href=&quot;https://drive.google.com/open?id=1m_RLYwqklWhjR5QdeLrqyjRRmgQ&amp;amp;usp=sharing&quot; rel=&quot;nofollow noreferrer&quot;&gt;this&lt;/a&gt;, which was done tracking one commercial jet from one airport to another which includes no amount of variation, and it takes a long time to do this live.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ideally I could get the general routes that these individual flights tend to follow, but to get an approximation of the actual routes between airports would be a whole lot better than I am know. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a perfect world there would be lat/lon/alt/ pairings of the paths with some sort of standard deviation on those points. I doubt that exists but anything that could get me closer to that would be excellent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Paying for something is not necessarily a problem, as long as I can prove it to my boss that it is what we need.&lt;/p&gt;&#xA;" OwnerUserId="14703" LastEditorUserId="8282" LastEditDate="2019-06-16T20:05:25.917" LastActivityDate="2019-06-16T20:05:25.917" Title="Where can I find the planned and flown paths for certain flight routes?" Tags="&lt;datasets&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="18" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="27281" PostTypeId="2" ParentId="27268" CreationDate="2016-04-29T19:21:19.123" Score="9" Body="&lt;p&gt;When I used to teach my IFR students, they usually spent only the first couple of hours with all of their instruments. I put them in all sorts of unusual attitudes and let them recover under the hood, and with &quot;failed&quot; instruments. And I sometimes included spins with the students I thought could handle it. That was what my instructor did to me, and I guess I carried on the tradition. It sucked. And I know my students had horrible thoughts of me at the time. But it made us better pilots. Especially in IMC. It taught me not to rely on the things that were  more likely to fail and to quickly be able to interpret what my instruments were telling me. I went for a month in training thinking the Attitude Indicator and Directional Gyro looked like a suction-cupped soap holder. I don't think it's hard to tell you're in a spin; you just have to know what your plane is saying to you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To your question: Is it possible to recover? Absolutely. Is it likely though? It depends. If you have a lot of altitude and you're in an aircraft that has decent spin characteristics, probably (especially since you mentioned prior spin training). But if you were at a couple thousand feet in a Piper Tomahawk, probably not. Would I recommend trying it? A big resounding NO!!!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And to your other question about AHRS: In a spin, the Attitude Indicator, no matter how accurate it might be, was the last thing I looked at in recovery. Unless it can demonstrate 100% reliability in all flight attitudes, it's safest to just assume it's lying to you. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Side Note: I recently did a balance function test with a physical therapist for an inner ear vertigo issue. She told me that pilots were some of the hardest people to test, specifically because we teach ourselves to ignore what our ears tell us. :-)&lt;/p&gt;&#xA;" OwnerUserId="383" LastActivityDate="2016-04-29T19:21:19.123" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27282" PostTypeId="2" ParentId="27278" CreationDate="2016-04-29T19:36:38.107" Score="2" Body="&lt;p&gt;Because the fuel-air mixture in a turbine is &lt;a href=&quot;https://aviation.stackexchange.com/questions/10034/if-jets-carried-pure-o2-to-use-for-combustion-would-they-be-more-efficient/10036#10036&quot;&gt;much leaner&lt;/a&gt; than what it would be for a &lt;a href=&quot;https://en.wikipedia.org/wiki/Stoichiometry&quot; rel=&quot;nofollow noreferrer&quot;&gt;stoichiometric&lt;/a&gt; combustion. It needs to stay lean to restrict the maximum gas temperature inside the engine - higher temperatures lead to exponentially shorter lives of the turbine components.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-04-29T19:36:38.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27283" PostTypeId="2" ParentId="27270" CreationDate="2016-04-29T20:54:17.267" Score="7" Body="&lt;p&gt;You are right, the horizontal tail of a conventional airplane appears to have a higher incidence, but the actual angle of attack is smaller than that of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The wing, flying ahead of the tail, produces downwash, so the flow at the tail location has a distinct downward component. The downwash angle can be calculated from the lift coefficient and the geometry of the aircraft: To simplify things, let's assume the wing is just acting on the air with the density $\rho$ flowing with the speed $v$ through a circle with a diameter equal to the span $b$ of the wing. If we just look at this stream tube, the mass flow is $$\frac{dm}{dt} = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift $L$ is then the impulse change which is caused by the wing and equal to weight. With the downward air speed $v_z$ imparted by the wing, lift is: $$L = \frac{b^2}{4}\cdot\pi\cdot\rho\cdot v\cdot v_z = S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$S$ is the wing area and $c_L$ the overall lift coefficient. If we now solve for the vertical air speed, we get $$v_z = \frac{S\cdot c_L\cdot\frac{v^2}{2}\cdot\rho}{\frac{b^2}{4}\cdot\pi\cdot\rho\cdot v} = \frac{2\cdot c_L\cdot v}{\pi\cdot AR}$$&#xA;with $AR = \frac{b^2}{S}$ the aspect ratio of the wing. Now we can divide the vertical speed by the air speed to calculate the angle by which the air has been deflected by the wing. Let's call it $\alpha_w$: $$\alpha_w = arctan\left(\frac{v_z}{v}\right) = arctan \left(\frac{2\cdot c_L}{\pi\cdot AR}\right)$$&#xA;A typical airliner cruise lift coefficient is 0.4, and a typical aspect ratio is around 8: This results in a downwash angle of nearly 2° if the lift distribution over span is elliptical. In reality, it is more triangular-shaped, so the downwash angle is larger near the center of the aircraft. Note that the engine nacelles of the &lt;a href=&quot;https://aviation.stackexchange.com/questions/1543/why-do-dc-9-and-md-82-have-engines-that-are-slightly-angled-upwards/1544#1544&quot;&gt;DC-9 and the MD-80 range&lt;/a&gt; are tilted 3° up to align them with the local flow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The resulting angle of attack is lower by those 3°, and if the angle of attack difference between wing and tail is less than that, the tail surface will appear angled upward. To achieve static stability, the tail will have to fly at a slightly &lt;a href=&quot;https://aviation.stackexchange.com/questions/3902/why-is-managing-cg-centre-of-gravity-important-for-aircraft/3927#3927&quot;&gt;lower angle of attack than the wing&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-04-29T21:00:19.107" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27289" PostTypeId="1" AcceptedAnswerId="27294" CreationDate="2016-04-30T10:01:27.903" Score="13" ViewCount="798" Body="&lt;p&gt;I was a passenger on an east to west flight recently. During the flight I was playing with Garmin Pilot's new &quot;Flight profile&quot; feature that nicely shows the wind speeds at various altitudes, and I noticed that we were flying against an 80+ knot headwind at FL320, but if we'd dropped to FL220 we'd shave about 40 knots of headwind. That seems pretty significant. A 1,000 NM flight with 355 knot ground speed (which we were cruising at) would save 17 minutes of cruise time with 40 knots less headwind. That's a 10% increase in efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the question is, did we stay (or even plan in the first place) to fly at FL 320 the entire cruise portion of the flight simply due to ATC needing to keep us there for traffic routing purposes,&#xA;Is there an even larger increase in fuel efficiency between FL320 and FL220 than 10%,&#xA;or is the difference negligible enough that it's not worth asking for a different altitude from ATC,&#xA;or some other factor not considered here?&lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-04-30T21:24:48.540" Title="Why might a passenger jet fly at altitudes in a strong headwind when the winds are more favorable at a different altitude?" Tags="&lt;air-traffic-control&gt;&lt;commercial-aviation&gt;&lt;flight-planning&gt;&lt;fuel&gt;&lt;commercial-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27290" PostTypeId="2" ParentId="27274" CreationDate="2016-04-30T12:04:27.983" Score="12" Body="&lt;p&gt;Basically, you put wheels on the skid and tow them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In some cases, towing wheels are attached to the skids (which usually have sleeves in them for mounting), and a tow bar is attached to the front (one or two sets of wheels may be attached to the skids), which is then towed by a vehicle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FOYnC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FOYnC.jpg&quot; alt=&quot;Helicopter towing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.incrediblediary.com/wp-content/uploads/2012/07/helicopter_WId4e_6648.jpg&quot; rel=&quot;noreferrer&quot;&gt;incrediblediary.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are also specialised tow carts available for helicopters, which basically grip the skids (usually in a couple of places on either side) and lift them up, after which the helicopter can be moved by the operator by controlling the cart.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/guyOG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/guyOG.jpg&quot; alt=&quot;Helicopter cart&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.hasmak.com.tr/yeni/dosyalar/images/v900_bell206.jpg&quot; rel=&quot;noreferrer&quot;&gt;hasmak.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-04-30T12:04:27.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27291" PostTypeId="1" AcceptedAnswerId="27313" CreationDate="2016-04-30T14:21:35.507" Score="6" ViewCount="453" Body="&lt;p&gt;If one centers the gyro-copter in a thermal and then &lt;a href=&quot;https://youtu.be/SxVM2a7OFQo?t=114&quot;&gt;simulates a hover facing headwind&lt;/a&gt;; can the gyro-copter climb up like that ? &#xA;Is it technically possible or is it advisable....&lt;/p&gt;&#xA;" OwnerUserId="1953" LastActivityDate="2016-05-02T01:16:02.203" Title="Can a gyro-copter soar?" Tags="&lt;theory&gt;&lt;experimental-aircraft&gt;&lt;thermals&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27292" PostTypeId="1" AcceptedAnswerId="27296" CreationDate="2016-04-30T14:33:29.070" Score="13" ViewCount="680" Body="&lt;p&gt;Some time ago, I came across a GIF of a Russian military airplane doing a Kulbit manoeuvre (Probably for showoff). How, in terms of control surface movement, does an airplane to the Kulbit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o3ehr.gif&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o3ehr.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Source: &lt;a href=&quot;https://www.reddit.com/r/interestingasfuck/comments/28w8yv/the_kulbit_maneuver_xpost_from_raviationgifs/&quot;&gt;Reddit&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="3201" LastEditDate="2016-04-30T20:03:25.360" LastActivityDate="2016-04-30T20:21:46.737" Title="How does an airplane do a Kulbit manoeuvre?" Tags="&lt;aerobatics&gt;&lt;maneuver&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27293" PostTypeId="1" AcceptedAnswerId="27352" CreationDate="2016-04-30T14:57:07.893" Score="12" ViewCount="1731" Body="&lt;p&gt;I'm a student participating in a design project wherein we have to develop a paper design for a payload to be airdropped from a C-130J.  Naturally, I'd like to look at the weight and balance of the C-130 to see what sort of limitations we have (since we'd like to literally fill the cargo bay with multiples of this payload), but it does not seem to be available anywhere.  I found a &lt;a href=&quot;https://play.google.com/store/apps/details?id=cni_mu_int.B4A.cnimu&quot; rel=&quot;nofollow noreferrer&quot;&gt;CNI-MU emulator&lt;/a&gt; on Google Play that gives some basic information (basic weight/arm, crew weight/arm, fuel weight/arm), and I have a loadmaster form from the &lt;a href=&quot;http://www.ustranscom.mil/dtr/part-iii/dtr_part_iii_app_v.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;2015 Defense Transport Regulations&lt;/a&gt; that shows me the cargo hold layout. However, something's not lining up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The default information loaded into the emulator places the basic weight at STA 730 and the fuel at STA 750, which is roughly where the aircraft ramp begins according to the DTR cabin layout (which labels it as corresponding to the B/E/H models, but, according to the DTR, it applies to the J model as well), but it seems strange because, according to the CNI-MU emulator, that's around the quarter-chord of the wing, which is a little behind the center of the cargo hold.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, I'm a bit confused and am looking for anyone who might be able to either make sense of the above or answer the following question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is the loading diagram for a C-130J (i.e., what is the basic weight/arm, crew arm, fuel arm, and payload stations within the cargo cabin)?&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="14720" LastEditorUserId="15311" LastEditDate="2017-12-10T10:53:31.257" LastActivityDate="2018-06-02T20:50:48.910" Title="What is the loading diagram for a C-130J?" Tags="&lt;weight-and-balance&gt;&lt;cargo&gt;&lt;c-130&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27294" PostTypeId="2" ParentId="27289" CreationDate="2016-04-30T19:04:50.363" Score="13" Body="&lt;p&gt;You assessment is flawed in that it does not take different air density in account.  You state the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FL320&lt;/li&gt;&#xA;&lt;li&gt;80 kt headwind&lt;/li&gt;&#xA;&lt;li&gt;355 kt groundspeed&lt;/li&gt;&#xA;&lt;li&gt;1000 nm distance&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and you are proposing descending to the following conditions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;FL220&lt;/li&gt;&#xA;&lt;li&gt;40 kt headwind&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;At 32,000 ft, standard conditions are around 275 hPa, 225 K and density of 0.43 kg m$^{-3}$.  If your 80 kt wind is a pure headwind, a 355 kt groundspeed translates into a 435 kt TAS. If we correct this TAS for the ambient conditions we get an indicated airspeed of about 255 KIAS.  This is the airspeed that really matters because it is what the airplane experiences as it interacts with the atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we descend to FL220, where standard conditions are 430 hPa, 244 K and 0.61 m$^{-3}$, an airspeed of 255 KIAS yields a TAS of 363 kt TAS.  If we have a headwind of 40 its, this yields a groundspeed of 323 kt.  This is about 30 kt slower than you were flying at FL320.  A flight of 1000 nm will take about 15 minutes longer to complete.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, it is most likely possible that the airplane you were in is capable of flying faster than 255 KIAS at FL220 and in fact is probably capable of somewhere around 310 KIAS.  Flying at 310 KIAS at FL220 will have true airspeed or 440 KTAS and with the 40 kt headwind a ground speed of 400 kt. This will get you to your destination faster, but at the expense of a much higher fuel burn. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is also likely that you could have been flying faster at FL320 (not sure what max mach number would have been for you), but also at the expense of burning more fuel.  If the airplane wasn't dispatched for the additional fuel burn to go faster at FL220, then after descending you would probably not have enough fuel to go fast enough to make up the difference in true airspeeds.&lt;/p&gt;&#xA;" OwnerUserId="258" LastEditorUserId="258" LastEditDate="2016-04-30T21:24:48.540" LastActivityDate="2016-04-30T21:24:48.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27295" PostTypeId="1" CreationDate="2016-04-30T19:53:13.493" Score="10" ViewCount="1292" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zo31e.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zo31e.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;I've put together a model plane in the form of an angel, and the planform is quite tail heavy (please see pic).&#xA;I'm trying to balance the plane with a lifting tail prop that makes the &quot;apparent&quot; CG in the place where the CG should be.&#xA;I've launched the plane twice. The first time it seemed like there wasn't enough forward thrust. The second time the tail rotor didn't have enough thrust and it pitched upwards. (Please see video links).&#xA;Will this concept work if tweaked properly?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/biX1fsdc-j8?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&#xA;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/Mt_OYPfmAZA?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="14723" LastActivityDate="2016-05-01T06:49:15.927" Title="Is it possible to balance a tail heavy plane with a vertical prop on its tail?" Tags="&lt;aircraft-design&gt;&lt;stability&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27296" PostTypeId="2" ParentId="27292" CreationDate="2016-04-30T20:14:29.980" Score="13" Body="&lt;p&gt;The Kulbit maneuver is a variation on the &lt;a href=&quot;https://aviation.stackexchange.com/questions/24292/pugachevs-cobra-aerodynamics-meaning-of-docile-pitch-behavior&quot;&gt;Cobra maneuver&lt;/a&gt; (Pugachev's Cobra) with a higher pitch rate and continuous positive pitch rate throughout the maneuver. It requires two things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A docile pitch behavior of the airframe over the full angle of attack range of 360°. Docile means that the pitch moments stay low and do not change abruptly with the angle of attack.&lt;/li&gt;&#xA;&lt;li&gt;Thrust vectoring nozzles to keep the pitch rate up.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;An electronic flight system is helpful to make execution easier, but is not strictly required. Also helpful is an engine-intake-combination which does not stall the compressor if the outer flow is reversed briefly. As you can see, the control surfaces only play a minor role - they are only important initially to start the pitch-up motion. This is done by negative elevator and/or positive canard deflection.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-04-30T20:21:46.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27297" PostTypeId="2" ParentId="27295" CreationDate="2016-04-30T20:31:15.050" Score="11" Body="&lt;p&gt;Tryin' to cheat the laws of stability, aren't we?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In both videos it is evident that the plane is unstable in pitch. Adding a lifting prop will not change this, because changes in the angle of attack will not affect this prop's lift force much. &lt;a href=&quot;https://aviation.stackexchange.com/questions/12507/what-does-it-mean-for-a-plane-to-be-aerodynamically-stable?rq=1&quot;&gt;Stability&lt;/a&gt; is achieved by shifting the center of gravity forward, so that changes in the angle of attack will produce additional forces which create a counteracting pitch moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, adding the motor will shift the center of gravity even further back. &lt;a href=&quot;https://aviation.stackexchange.com/questions/8077/why-did-moving-the-cg-aft-on-the-wright-brothers-plane-improve-handling/8079?s=2%7C0.1293#8079&quot;&gt;In some cases this helped&lt;/a&gt; because the increased pitch inertia made it easier for the pilot to keep the aircraft under control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to keep the center of gravity so far backward, add artificial stability with a pitch rate sensor and a microcontroller which deflects the elevator appropriately. &lt;a href=&quot;http://www.freetronics.com.au/blogs/news/7956857-diy-model-aircraft-remote-control-with-arduino#.VyWmrmMape8&quot; rel=&quot;nofollow noreferrer&quot;&gt;There are many pages&lt;/a&gt; with &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/B009YDK6NA&quot; rel=&quot;nofollow noreferrer&quot;&gt;Arduino-controlled artificial stability&lt;/a&gt; solutions - take your pick!&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-05-01T06:49:15.927" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27298" PostTypeId="2" ParentId="27295" CreationDate="2016-04-30T22:58:31.990" Score="0" Body="&lt;p&gt;Yes, &lt;em&gt;if tweaked properly&lt;/em&gt;. You need it to be able to articulate, and employ the same type of software that makes Ospreys &lt;strike&gt; not crash so much anymore&lt;/strike&gt; fly, and either have two of them or an additional tail rotor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RzL6J.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RzL6J.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3497" LastActivityDate="2016-04-30T22:58:31.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27299" PostTypeId="2" ParentId="27291" CreationDate="2016-04-30T23:00:41.570" Score="2" Body="&lt;p&gt;Any aircraft, from a helicopter to a 747, can soar. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All it has to do is enter and maintain its position in rising air. How the pilot accomplishes that would be based on picking a strategy for staying in the rising air, and using his skill to do it.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-04-30T23:00:41.570" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27300" PostTypeId="1" AcceptedAnswerId="27303" CreationDate="2016-05-01T01:23:01.640" Score="34" ViewCount="14018" Body="&lt;p&gt;Why is the fan in a turbofan different than a propeller in a small airplane? Why do propellers typically have 2 or 3 blades, but the fan has a lot more? And why is the fan shrouded but the propeller open?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I read that a ducted fan is more efficient at very slow speeds (it generates more static thrust than an open prop), but at high speeds the drag becomes too great and you're better off with an open propeller. Which is why they use a ducted fan in hovercrafts, for instance. But if that's true, shouldn't the fan in a turbofan be open (unshrouded), considering the high speeds (higher than a propeller)? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, how does the fan get away with supersonic tip speeds and the prop don't? Would the fan be more efficient if tip speeds were lower?&lt;/p&gt;&#xA;" OwnerUserId="14683" LastEditorUserId="5517" LastEditDate="2016-05-02T16:27:18.080" LastActivityDate="2020-12-16T22:43:30.077" Title="How does a fan differ from a propeller?" Tags="&lt;propeller&gt;&lt;turbofan&gt;" AnswerCount="5" CommentCount="2" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27301" PostTypeId="2" ParentId="27295" CreationDate="2016-05-01T05:53:12.107" Score="0" Body="&lt;p&gt;Maybe. Pitch stability could be the biggest problem. The &quot;tail rotor&quot; will have to vary its thrust according to airspeed in order to match what the wing is doing. Let's say the aircraft is in straight and level flight, with the tail rotor delivering an appropriate amount of thrust. Now if the airspeed increases only slightly, the wings will generate slightly more lift, but because of their position, will create a significant nose-up moment, so the aircraft will pitch up rather abruptly. Of course, only a slight increase in tail rotor thrust will offset it and keep the aircraft in balance. You might want to ditch the traditional tail surface altogether and control the tail rotor via a feedback control system cued by angle of attack. Your flight control input would then adjust the target angle.&lt;/p&gt;&#xA;" OwnerUserId="3218" LastActivityDate="2016-05-01T05:53:12.107" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27302" PostTypeId="2" ParentId="27256" CreationDate="2016-05-01T08:03:48.923" Score="2" Body="&lt;p&gt;&lt;a href=&quot;http://www.radioreference.com/apps/db/?rpt=6&amp;amp;aid=2236&quot; rel=&quot;nofollow noreferrer&quot;&gt;This is a useful site&lt;/a&gt; for the Oakland (ZOA) Air Route Traffic Control Center (ARTCC), and the locations of these match up with the RCO locations on the sectional. It seems Mt Tamalpais RCAG is the one that applies to my area. The list seems a little out of date, however, as the location of &quot;Priest - RCAG&quot; doesn't have anything on the sectional, or in Google Maps.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further, there is an &lt;a href=&quot;http://faa.gov/about/office_org/headquarters_offices/ato/service_units/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA site&lt;/a&gt; depicting RCOs and frequencies for &lt;strong&gt;Alaska&lt;/strong&gt;.&lt;/p&gt;&#xA;" OwnerUserId="995" LastEditorUserId="995" LastEditDate="2020-01-21T19:18:10.090" LastActivityDate="2020-01-21T19:18:10.090" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27303" PostTypeId="2" ParentId="27300" CreationDate="2016-05-01T10:50:48.153" Score="24" Body="&lt;p&gt;The simple answer that covers the majority of engines is that a fan has a shroud. The possible exception are unducted fans or &lt;a href=&quot;https://en.wikipedia.org/wiki/Propfan&quot; rel=&quot;nofollow noreferrer&quot;&gt;Open Rotor Engines&lt;/a&gt;, which are a hybrid between a turboprop and a fan engine.&lt;/p&gt;&#xA;&lt;p&gt;A more scientific answer is based on the difference in disk loading: How much power per disk area can be pumped into the fan for propulsion. For propellers, this is distinctively less than for fans. Some examples:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Cessna 172 with O-320 engine (150 hp) and McCauley 1C160 prop (1.9 m diameter): 39.45 kW/m².&lt;/li&gt;&#xA;&lt;li&gt;P-51D with Packard-Merlin 1650 (1590 hp) and Hamilton-Standard prop (3.4 m diameter): 130.59 kW/m².&lt;/li&gt;&#xA;&lt;li&gt;Lockheed C-130H Hercules with Allison T-56 engine (4590 hp) and Aeroproducts propeller (4.1 m diameter): 259.25 kW/m².&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;With jets, this comparison needs power when thrust is listed. Therefore, we make the heroic assumption that the speed at the fan is Mach 0.4 in static conditions and thrust is split according to bypass ratio (which is completely imprecise but will do for the purpose here):&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;BAe 146 with &lt;a href=&quot;https://en.wikipedia.org/wiki/Lycoming_ALF_502&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lycoming ALF 502&lt;/a&gt; (31 kN static thrust, 5.7:1 bypass ratio and 1.02 m fan diameter): 4254.35 kW/m².&lt;/li&gt;&#xA;&lt;li&gt;Boeing 747-200 with &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt &amp;amp; Whitney JT9D&lt;/a&gt; (213 kN static thrust, 5:1 bypass ratio and 2.34 m fan diameter): 5388.74 kW/m².&lt;/li&gt;&#xA;&lt;li&gt;Boeing 777 with &lt;a href=&quot;http://web.stanford.edu/%7Ecantwell/AA283_Course_Material/GE90_Engine_Data.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;GE90&lt;/a&gt; (388.8 kN thrust at take-off, 8.4:1 bypass ratio and 3.124 m fan diameter): 6077.23 kW/m².&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;I guess by now you see where this is heading: Turbofans are simply a different class when thrust per frontal area is concerned. And for this to be possible, three conditions must be met:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;A well-designed intake which produces uniform flow over the engine face. The shroud is only the consequence of providing the fan with an intake.&lt;/li&gt;&#xA;&lt;li&gt;A high &lt;a href=&quot;http://quest.arc.nasa.gov/qna/questions/Propellers_Activity_Factor.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;solidity factor&lt;/a&gt; of the fan/propeller (the ratio of the total blade area of the propeller to the disk swept out when the prop turns)&lt;/li&gt;&#xA;&lt;li&gt;High dynamic pressure at the engine face, so the engine power can be absorbed by the fan/propeller.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;Note that those conditions depend on each other: Without the solidity, much less power could be absorbed. Without the intake, the supersonic flow at the fan tips would produce &lt;a href=&quot;https://aviation.stackexchange.com/questions/21683/did-the-xf-84h-thunderscreech-really-cause-900-sonic-booms-per-minute&quot;&gt;horrible losses and noise&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Now for the crazy ones. The misfits. The rebels. The troublemakers. The round pegs in the square holes:&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Antonov 70 with &lt;a href=&quot;https://en.wikipedia.org/wiki/Progress_D-27&quot; rel=&quot;nofollow noreferrer&quot;&gt;Progress D-27&lt;/a&gt; (14,000 hp and 4.5 m prop diameter): 656.4 kW/m².&lt;/li&gt;&#xA;&lt;li&gt;MD-81 with GE36 UDF (&lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/apl/research/aircraft_technology/cleen/reports/media/Open_Rotor_Public_Final_Report.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;6661 kN thrust at max climb and 3.25 m prop diameter&lt;/a&gt;): 803 kW/m².&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Here it is hard to make a clear call whether these are fans or propellers. Their proper name &amp;quot;propfans&amp;quot; hints at that already.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;A last word on terminology&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Efficiency is a measure how much effort is needed for a certain result. An efficient prop needs less power per unit of thrust produced. It has &lt;a href=&quot;https://aviation.stackexchange.com/questions/23009/what-are-the-advantages-of-more-than-4-propeller-blades/23015#23015&quot;&gt;few blades&lt;/a&gt;, turns slowly and has a big diameter. A subsonic fan would be more efficient, but would create much less thrust for a given size.&lt;/p&gt;&#xA;&lt;p&gt;If you want to express the capacity for thrust creation at a specific diameter, use disk loading, not efficiency.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-12-16T22:43:30.077" LastActivityDate="2020-12-16T22:43:30.077" CommentCount="15" ContentLicense="CC BY-SA 4.0" />
  <row Id="27305" PostTypeId="1" AcceptedAnswerId="27307" CreationDate="2016-05-01T15:31:36.370" Score="6" ViewCount="7098" Body="&lt;p&gt;This is a followup to &lt;a href=&quot;https://aviation.stackexchange.com/q/23743/8730&quot;&gt;my other question&lt;/a&gt; on this topic. Figured I'd just make it a whole separate question. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The plates below show STAR arrivals to KMEM. The points along the route are marked with two different symbols. When I look in the FAA guide it refers to the triangular symbols as non-reporting &lt;em&gt;fixes&lt;/em&gt; and the star shaped symbols as non-reporting &lt;em&gt;waypoints&lt;/em&gt;. What is the difference between the two? Why are they marked with different symbols? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PVEZ1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PVEZ1.jpg&quot; alt=&quot;DAWGG TWO ARRIVAL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LPhLp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LPhLp.jpg&quot; alt=&quot;HOBRK ONE ARRIVAL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ewXZy.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ewXZy.jpg&quot; alt=&quot;Fixes/ATC Reporting Requirements Legend&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="1696" LastEditDate="2020-05-26T17:49:06.327" LastActivityDate="2020-05-26T17:49:06.327" Title="What is the difference between fixes and waypoints on an arrival plate?" Tags="&lt;navigation&gt;&lt;aeronautical-charts&gt;&lt;ifr-navigation&gt;&lt;waypoint&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="27306" PostTypeId="2" ParentId="27305" CreationDate="2016-05-01T16:19:09.737" Score="2" Body="&lt;p&gt;According to the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/pcg_4-03-14.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pilot/Controller Glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;WAYPOINT− A predetermined geographical position used for&#xA;  route/instrument approach definition, progress reports, published VFR&#xA;  routes, visual reporting points or points for transitioning and/or&#xA;  circumnavigating controlled and/or special use airspace, that is&#xA;  defined relative to a VORTAC station or in terms of latitude/longitude&#xA;  coordinates.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;FIX− A geographical position determined by visual reference to the&#xA;  surface, by reference to one or more radio NAVAIDs, by celestial&#xA;  plotting, or by another navigational device.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They are pretty much used interchangibly, but a &lt;em&gt;fix&lt;/em&gt; is just a point in space, where as a &lt;em&gt;waypoint&lt;/em&gt; is a &lt;em&gt;fix&lt;/em&gt; where the pilot might actually do something, although this doesn't always hold (e.g., the MAP)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes one or the other may be built directly into the nomenclature, like &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;DME &lt;em&gt;Fix&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;Final Apprach &lt;em&gt;Fix&lt;/em&gt; (FAF)&lt;/li&gt;&#xA;&lt;li&gt;Visual Descent &lt;em&gt;Point&lt;/em&gt; (VDP)&lt;/li&gt;&#xA;&lt;li&gt;Missed Approach &lt;em&gt;Point&lt;/em&gt; (MAP)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Sometimes you have to be very careful using fix or waypoint:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Missed Approach Point&lt;/em&gt; (MAP) -- where the land/missed decision must be made. It uses &lt;em&gt;point&lt;/em&gt; and not &lt;em&gt;fix&lt;/em&gt; because it may be determined by DH, a timer, or a GPS fix, even on the same approach chart.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;em&gt;Missed Approach Fix&lt;/em&gt; (MAF) -- where the missed approach hold is&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In this example for the ILS at KMEM, the MAP may be determined either by:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;466MSL DA with a working GS&lt;/li&gt;&#xA;&lt;li&gt;4:18 seconds @60KIAS from the FAF with GS INOP&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Z6lZV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Z6lZV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-05-01T17:41:38.447" LastActivityDate="2016-05-01T17:41:38.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27307" PostTypeId="2" ParentId="27305" CreationDate="2016-05-01T17:15:51.447" Score="5" Body="&lt;p&gt;As described in the &lt;a href=&quot;https://aviation.stackexchange.com/a/23745/136&quot;&gt;answer to the previous question&lt;/a&gt;, all of the points on the chart are both waypoints and fixes. The difference between the printed icons is how they are identified from the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The waypoints marked by hexagons, some with darkened edges and some printed inside a square, note where the waypoint is on top of a VOR. This includes Razorback, Walnut Ridge, Gilmore, and Memphis. The icons with bolded sides are a VOR collocated with TACAN; inscribed inside a square notes a VOR collocated with a DME station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Triangles are waypoints determined by a radial and distance from a VOR station. The star icons are determined by an RNAV (area navigation) system, which does not require the aircraft to fly a particular VOR radial to determine its course. Note that the procedure you provided is not available for RNAV-capable aircraft, likely because there is an RNAV arrival procedure that is preferred by ATC.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;To fly the procedure, starting from the left, a pilot would identify the Razorback (RZC) point by their &lt;a href=&quot;https://aviation.stackexchange.com/questions/26031/what-are-the-differences-between-an-obs-a-cdi-a-heading-indicator-and-an-hsi&quot;&gt;CDI&lt;/a&gt; showing that they had flown over the beacon itself. The next waypoint is MARBI; that is determined by flying along the 098 degree radial to a distance of 34 NM from RZC. Similarly, IGLOO can be identified by flying the 098 degree radial another 85 NM for a total distance of 119 NM. The distinct icons tell pilots how to identify the waypoints using their onboard equipment, but they otherwise have the same meaning.&lt;/p&gt;&#xA;" OwnerUserId="136" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-05-01T17:15:51.447" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27308" PostTypeId="2" ParentId="27300" CreationDate="2016-05-01T17:20:24.353" Score="2" Body="&lt;p&gt;First, let's start with the simplest machine, the &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Screw_(simple_machine)&quot; rel=&quot;nofollow&quot;&gt;screw&lt;/a&gt;&lt;/em&gt;, which converts rotational motion to linear motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;fan&lt;/em&gt; is a &lt;em&gt;screw&lt;/em&gt; whose primary purpose is to move the fluid (air for a plane or water for a boat) which surrounds it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;em&gt;propeller&lt;/em&gt; is a &lt;em&gt;screw&lt;/em&gt; whose primary purpose is to move (&lt;em&gt;propel&lt;/em&gt;) the object that it is attached to, such as a boat or a prop plane. And indeed, mariners use the term &lt;em&gt;screw&lt;/em&gt; instead of &lt;em&gt;prop&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of &lt;em&gt;turboprop&lt;/em&gt; and &lt;em&gt;turbofan&lt;/em&gt;, the turboprop uses its prop as the primary means of motion, whereas in the &lt;em&gt;turbofan&lt;/em&gt;, the fan simply increases the velocity of the air, but doesn't provide the primary means of motion for the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3504" LastEditDate="2016-05-02T08:15:16.437" LastActivityDate="2016-05-02T08:15:16.437" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27309" PostTypeId="5" CreationDate="2016-05-01T19:51:41.210" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-05-01T19:51:41.210" LastActivityDate="2016-05-01T19:51:41.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27310" PostTypeId="4" CreationDate="2016-05-01T19:51:41.210" Score="0" Body="Instrument meteorological conditions (IMC) are the weather conditions that require to fly primarily by reference to instruments, under instrument flight rules (IFR).  " OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-05-01T22:16:51.267" LastActivityDate="2016-05-01T22:16:51.267" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27312" PostTypeId="1" AcceptedAnswerId="27314" CreationDate="2016-05-02T01:10:51.400" Score="10" ViewCount="10475" Body="&lt;p&gt;In a METAR report gusts of wind are shown with a &lt;code&gt;G&lt;/code&gt; after the wind speed.  When will gusts be reported?  I have seen reports that show:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;12017G20&lt;/li&gt;&#xA;&lt;li&gt;12010G20&lt;/li&gt;&#xA;&lt;li&gt;12003G20&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-05-02T01:56:13.657" Title="What constitutes a wind gust in a METAR report?" Tags="&lt;weather&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27313" PostTypeId="2" ParentId="27291" CreationDate="2016-05-02T01:16:02.203" Score="2" Body="&lt;p&gt;I need to work out the math for this, but an issue complicating the question is that the L/D of the gyrocopter would change in the updraft.  So, like a helicopter in autorotation, a gyrocopter derives lift from flow passing upwards through the rotor as it flies forward on its propeller.  However, if the aircraft is in a vertical updraft, the freestream is no longer directed horizontally, but more vertically, increasing the angle of attack on the rotor blades and directing your vehicle's drag force in the upward direction (magnitude and direction, naturally, depends on your flight speed, thermal strength, etc.).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, gyrocopters have at cyclic and collective pitch control (generally speaking), so you could vary the collective in order to maintain a lower angle of attack, gain stall margin, and maintain altitude...or you could take advantage of the updraft on your rotor to gain altitude for &quot;free&quot;!  This also assumes that you have sufficient collective pitch travel to get your blades at a low enough angle of attack to stop producing upward-directed thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could try to pitch over too, thus redirecting the rotor thrust vector forward and spoiling a lot of the inflow, but this is starting to get into the downside of thermalling in helicopters: namely, that, if the updraft is sufficiently strong to stall your blades (no matter the pitch setting) but also strong enough that the vertical drag on the airframe can induce a climb...it's not going to be a good day.  I'm thinking primarily of updrafts that occur in the presence of thunderstorms--they have been known to be strong enough to suck aircraft up into the clouds.  Similarly, if you make your way out of the thermal, they are generally surrounded by regions of strong sink because of the recirculating air (&lt;a href=&quot;http://www.drjack.info/INFO/DELMONTE/thermal.page.html&quot; rel=&quot;nofollow&quot;&gt;http://www.drjack.info/INFO/DELMONTE/thermal.page.html&lt;/a&gt;), which not only is going to load the blades completely the opposite of how they were in the thermal (so your inertial loads spike, provided you don't have mast bumping problems...in which case you lose the aircraft right then), but, if the sink is strong enough, you might find yourself in vortex-ring-state or the like and lose control--if only temporarily.  At least from my brief experience in an S-300Cbi and R22, helicopters don't like to fly, so even brief periods of control loss would be bad.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yeah, I think it's technically feasible, and, in some cases, very dangerous.  I wouldn't try to set an endurance record in a rotary winged aircraft doing this.&lt;/p&gt;&#xA;" OwnerUserId="14720" LastActivityDate="2016-05-02T01:16:02.203" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27314" PostTypeId="2" ParentId="27312" CreationDate="2016-05-02T01:56:13.657" Score="13" Body="&lt;p&gt;The definition of &quot;Wind Gust&quot; for METAR reports can be found in the &lt;a href=&quot;http://www.ofcm.gov/fmh-1/fmh1.htm&quot;&gt;Federal Meteorological Handbook No. 1&lt;/a&gt;, chapter 5:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;5.4.4 Wind Gust.&lt;/strong&gt; The wind speed data for the most recent 10 minutes shall be examined to evaluate the&#xA;  occurrence of gusts. Gusts are indicated by rapid fluctuations in wind speed with a variation of 10 knots&#xA;  or more between peaks and lulls. The speed of a gust shall be the maximum instantaneous wind speed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="675" LastActivityDate="2016-05-02T01:56:13.657" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27317" PostTypeId="2" ParentId="15954" CreationDate="2016-05-02T16:22:45.017" Score="2" Body="&lt;p&gt;Adverse Yaw created by the propellor will vary based on aircraft and design. Lots of modern single engine aircraft do things to counter act adverse yaw but if we take a pretty neutral aircraft design and apply the tabs you reference all you will see is a slightly more aggressive rudder. Since there is a tab in each direction in a centered situation they will cancel each other out however they will cause the rudder to have a more drastic impact at smaller angles of deflection.    &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What actually happens? Does the neutral position of the rudder change&#xA;  at different power settings when flying straight and level? Does this&#xA;  arrangement reduce your foot workload compared to other aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The neutral position of the rudder will always change a bit as the power settings vary. For this you have &lt;a href=&quot;https://en.wikipedia.org/wiki/Trim_tab&quot; rel=&quot;nofollow&quot;&gt;rudder trim&lt;/a&gt;. Generally speaking a lot of GA planes have a bit of left rudder trim always in to counteract &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow&quot;&gt;P-Factor&lt;/a&gt; some even have permanent design features to do so. It should also be noted that &lt;a href=&quot;https://en.wikipedia.org/wiki/P-factor&quot; rel=&quot;nofollow&quot;&gt;P-Factor&lt;/a&gt; is most prominent at high angles of attack and high power settings (takeoff and climb out) generally this also means lower airspeeds. Once you settle into cruise its effects are decreased. I have never felt that it adds to my work load when flying but &lt;a href=&quot;https://en.wikipedia.org/wiki/ERCO_Ercoupe&quot; rel=&quot;nofollow&quot;&gt;Ercoupe pilots&lt;/a&gt; may have a different opinion on that.... The design you mention does not really reduce workload, for that you would need something like a &lt;a href=&quot;http://www.aopa.org/News-and-Video/All-News/2010/December/1/Yaw-dampers&quot; rel=&quot;nofollow&quot;&gt;yaw damper&lt;/a&gt; some new planes like the &lt;a href=&quot;http://cirrusaircraft.com/aircraft/sr22/&quot; rel=&quot;nofollow&quot;&gt;Cirrus SR22 have them&lt;/a&gt;. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-02T16:22:45.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27318" PostTypeId="1" AcceptedAnswerId="27425" CreationDate="2016-05-02T17:16:10.837" Score="11" ViewCount="2055" Body="&lt;p&gt;There is a stem that is located on the underside of the airplane between the drain valves for the fuel strainer and reservoir tank. It looks like a small stem that is protruding. &lt;a href=&quot;https://i.stack.imgur.com/wu112.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wu112.jpg&quot; alt=&quot;picture of stem&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have noticed it leaks a small amount of fuel (1 drip per 5 seconds). I am going to talk t my instructor about it but wanted to know what it was called. I am not seeing it in the fuel system diagram. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/raaEI.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/raaEI.jpg&quot; alt=&quot;fuel diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Updates:&#xA;I believe it is a part of the electric auxiliary fuel pump, but want any input. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft is a Cessna 172R made in 1997. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is 100LL that is dripping.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the fluid dripping.... Not water. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/ulBo5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ulBo5.jpg&quot; alt=&quot;collected 100LL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11216" LastEditorUserId="11216" LastEditDate="2016-05-03T18:02:09.257" LastActivityDate="2016-05-07T22:18:04.767" Title="What is this stem on the underside of a Cessna 172R (1997)?" Tags="&lt;fuel&gt;&lt;cessna-172&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27320" PostTypeId="2" ParentId="27300" CreationDate="2016-05-03T00:48:12.167" Score="2" Body="&lt;p&gt;In simple terms, the working principle is different:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A propeller is a rotating wing. This means that its main working principle is the Bernoulli principle. A difference in pressures (i.e. low pressure in the front and high pressure in the back) causes the plane to move forward. Is the same as in the helicopter rotors. See &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_(force)&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Lift_(force)&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Airfoil&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Airfoil&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The turbofan is mainly a reactor. This means that its main working principle is Newton's third law. The high velocity air that is forced trough the nozzle pushes the plane forward. The same as in a garden hose. See &lt;a href=&quot;https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer one of your additional questions, the one that is less efficient at high velocities is the propeller. This is because, in the propeller, at high velocities the air is flowing from the front to the back causing the pressure to rise at the front thus stalling the propeller. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the other hand in the turbofan, the additional pressure at the front actually helps the air to be forced trough the nozzle increasing performance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At extremely high velocities, however, the drag from the fan becomes very high and the speed is limited again (but at a higher velocity than in the propeller.) To achieve even more velocity, the rotating blades are removed and the air is forced trough the compressor because of the very high pressure at the front (See ramjets.) The working principle of ramjet is also Newton's third law.&lt;/p&gt;&#xA;" OwnerUserId="13210" LastEditorUserId="13210" LastEditDate="2016-05-03T18:50:51.623" LastActivityDate="2016-05-03T18:50:51.623" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27321" PostTypeId="1" CreationDate="2016-05-03T04:02:59.867" Score="7" ViewCount="3846" Body="&lt;p&gt;I want to know if there are any standard factors for determining maximum wing camber and thickness for heavy and light airplanes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm using an optimization process to find the best wing shape to reach the best aerodynamics. E.g. in cruise mode to find the maximum lift-over-drag ratio, maybe choosing a thinner camber or thickness has a higher C&lt;sub&gt;L&lt;/sub&gt; over C&lt;sub&gt;D&lt;/sub&gt; ratio, but may lead to problems with structural limits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can anyone help me with some good references on the appropriate limits of changes in both maximum thickness and camber?&lt;/p&gt;&#xA;" OwnerUserId="14747" LastEditorUserId="5517" LastEditDate="2016-05-03T16:35:35.093" LastActivityDate="2019-08-13T16:39:09.923" Title="How can we determine the maximum camber and thickness for airplane wings?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27322" PostTypeId="1" AcceptedAnswerId="27323" CreationDate="2016-05-03T04:47:05.107" Score="6" ViewCount="1182" Body="&lt;p&gt;I'm planning a trip in a Cessna 182T and was calculating fuel requirements and started wondering. I have always assumed that fuel consumption is in US Gallons (or 3.785 litres) but I can't find a section in the Pilot's Operating Handbook (POH) that really confirms this. The fuel tank capacity is expressed in USG so I reckon it's close to assume that this implies that GPH is US gallons per hour. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a Imp. Gallon to Liter and Imp Gallon to US Gallon conversion table in the POH, when do we need Imp. Gallons?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any comments, did I miss something?&lt;/p&gt;&#xA;" OwnerUserId="1957" LastEditorUserId="19" LastEditDate="2016-11-21T09:08:11.250" LastActivityDate="2016-11-21T09:08:11.250" Title="Does the Cessna POH state the fuel consumption in Imperial or US Gallons?" Tags="&lt;fuel&gt;&lt;units&gt;&lt;poh&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27323" PostTypeId="2" ParentId="27322" CreationDate="2016-05-03T05:11:29.530" Score="3" Body="&lt;p&gt;The plane was certified with US Gallons. Use those for fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The conversion tables are there in case your FBO's fuel pump is calibrated in L or Imp Gal.&lt;/p&gt;&#xA;" OwnerUserId="3504" LastEditorUserId="3825" LastEditDate="2016-05-03T11:37:21.930" LastActivityDate="2016-05-03T11:37:21.930" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27324" PostTypeId="2" ParentId="27322" CreationDate="2016-05-03T05:12:55.713" Score="0" Body="&lt;p&gt;I am currently flying cessna 152(ii) and I have my POH which is from the year of 1979. The fuel per consumption and other performance data are given in the performance section of the POH at section 5. The arrangement of data and other information are similar for all the POH. So you will get it in the section 5 probably. There are some tables which dictates information regarding cruise range, endurance, cruise performance. In the cruise performance chart you will get the consumption of fuel in accordance with temperature and RRP and if you have manifold pressure system you will have it on this chart hopefully. And for the calculation of fuel you will depend on the the calibration of the gauge you have in the cockpit. I think the on the chart of POH the fuel consumption is given in US Gallon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hopefully this will help you. &lt;/p&gt;&#xA;" OwnerUserId="13956" LastActivityDate="2016-05-03T05:12:55.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27325" PostTypeId="1" AcceptedAnswerId="27331" CreationDate="2016-05-03T09:40:31.493" Score="7" ViewCount="1699" Body="&lt;p&gt;Why do almost all civilian VTOL aircraft existing today use propellers (or rotors) for take off and landing and not jet engines (as the Harrier does)? Is there a technical reason for this?&lt;/p&gt;&#xA;" OwnerUserId="12911" LastEditorUserId="7532" LastEditDate="2016-05-03T20:36:58.643" LastActivityDate="2019-08-09T17:51:52.763" Title="Can jet engines be used for VTOL civilian aircraft?" Tags="&lt;jet-engine&gt;&lt;landing&gt;&lt;takeoff&gt;&lt;propeller&gt;" AnswerCount="5" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27326" PostTypeId="2" ParentId="27325" CreationDate="2016-05-03T10:30:08.727" Score="0" Body="&lt;p&gt;Jet engines have already been used for VTOL aircraft, see the &lt;a href=&quot;https://en.wikipedia.org/wiki/British_Aerospace_Sea_Harrier&quot; rel=&quot;nofollow&quot;&gt;Harrier&lt;/a&gt; or the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II&quot; rel=&quot;nofollow&quot;&gt;Joint Strike Fighter&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-05-03T10:30:08.727" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27327" PostTypeId="2" ParentId="27325" CreationDate="2016-05-03T11:48:56.957" Score="1" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL#Jet_lift&quot; rel=&quot;nofollow&quot;&gt;Wikipedia page on VTOL has a whole section on the history of &quot;jet lift&quot; VTOL aircraft&lt;/a&gt;. It includes some pictures of the Harrier &quot;Jump Jet&quot;, which is probably the most widely recognisable VTOL fixed-wing, and has a jet engine. I think the only reason &quot;almost all&quot; VTOL aircraft use propellors is that almost all VTOL aircraft are helicopters. VTOL fixed-wing aircraft turn out to be quite hard (read: expensive) to get right and not many designs (with props or jets) have made it into production.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-05-03T11:48:56.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27328" PostTypeId="1" AcceptedAnswerId="27329" CreationDate="2016-05-03T11:52:04.493" Score="35" ViewCount="10055" Body="&lt;p&gt;If a plane has been delayed at the origin how does it make up for the lost time? Does the pilot need any special permission from ATC to increase the speed so that it can cover the lost time or has the pilot the power to make such kind of decisions?&lt;/p&gt;&#xA;" OwnerUserId="14755" LastEditorUserId="1467" LastEditDate="2016-05-03T11:56:06.977" LastActivityDate="2016-05-03T22:11:26.353" Title="How can an airliner make up for time lost?" Tags="&lt;airline-operations&gt;" AnswerCount="6" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27329" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T12:03:22.587" Score="38" Body="&lt;p&gt;According to ICAO Annex II (Rules of the air) 3.6.2.2(b):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Variation in true airspeed: if the average true airspeed at cruising&#xA;  level between reporting points varies or is expected to vary by plus&#xA;  or minus 5 per cent of the true airspeed, from that given in the&#xA;  flight plan, the appropriate air traffic services unit shall be so&#xA;  informed.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So the pilot in command has the right to increase speed, just as well as the air traffic controller has the right to limit it. However, as airliners normally cruise fairly close to their maximum speeds, this isn’t very effective. Recovering lost time by increasing speed is at best 1 to 3 minutes per hour.&lt;br&gt;&#xA;Better ways are to request possible shortcuts from ATC and change altitude for better wind and temperature.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="2143" LastEditDate="2016-05-03T15:15:06.337" LastActivityDate="2016-05-03T15:15:06.337" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="27331" PostTypeId="2" ParentId="27325" CreationDate="2016-05-03T12:05:45.900" Score="12" Body="&lt;h1&gt;Can?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Of course they &lt;em&gt;can&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Does it make sense?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;No, it does not.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A VTOL needs thrust at least equal to its weight. That is much more than a fixed-wing aircraft (HTOL) needs. Airliners have lift-to-drag ratio around 18–20. That is in clean configuration; in landing configuration it might be about half (~10) and we need twice as much thrust in case an engine fails, so around ¼ weight. So a VTOL would need 4 times as much thrust as a HTOL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Likely more, because the craft would still have to be capable of reasonably controlled landing in case of engine failure. And while rotorcraft can do that by autorotation and pilot of Harrier or F-35B can simply eject, jet-powered civilian VTOL would only have the remaining engines for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now fortunately thrust and power are only indirectly related. To create thrust, force must be applied to the air. This force accelerates air, giving it some momentum and some kinetic energy. Thrust is (change of) momentum per time and momentum is mass time velocity while power is (change of) energy per time and energy is ½ mass times speed &lt;em&gt;squared&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we can produce a lot of thrust with little power by accelerating a &lt;em&gt;lot of air by a little&lt;/em&gt;. Which means large propeller: a rotor. That's how helicopters get enough lift/thrust with reasonably small engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately rotors are not very practical for flying fast. One would also be rather difficult to tilt. That's why V-22 Osprey and Augusta-Westland AW603 use a compromise that is somewhere between; large enough to still have good efficiency in hover and small enough to be possible to tilt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What would definitely &lt;em&gt;not&lt;/em&gt; be efficient for hover is a jet though. Jets are small and can't affect that much air; what they can is accelerate it a lot. That is necessary for flying fast, but it is terribly inefficient when flying slowly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military jets don't care. They want so powerful engine to fly very fast anyway and they don't care for efficiency much as decisive edge in combat is worth a lot of money. But for civilian transport the small advantage of being able to land closer to destination would not outweigh the disadvantage of being several times more expensive to operate. Flying the long distance with HTOL to a nearby airport and, if the destination is not reachable by car, hiring a helicopter just for the final part of the trip ends up being a lot cheaper.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-05-03T12:05:45.900" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27332" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T12:28:15.610" Score="3" Body="&lt;p&gt;On &lt;a href=&quot;https://www.eurocontrol.int/network-operations&quot; rel=&quot;nofollow&quot;&gt;NMOC&lt;/a&gt; (Network Manager Operations Centre) there is one member of each airline, and in case of fleet delays, due to weather for example, they discuss and instruct the ATC  to expedite one or some flights, clearing them to fly direct, and sometimes, overtake leading traffics on the queue.&lt;/p&gt;&#xA;" OwnerUserId="14354" LastEditorUserId="524" LastEditDate="2016-05-03T18:41:28.133" LastActivityDate="2016-05-03T18:41:28.133" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27333" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T14:30:13.530" Score="-2" Body="&lt;p&gt;On some planes (airplus, sorry no reference) there is a “sprint mode” that uses more fuel but goes faster.    Airlines may therefore decide to time their flights not using the “sprint mode”, so as to save fuel costs, but be willing to use it if they are running late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flights are also timed so that can keep to timings even if the wind is in the “wrong” direction,  therefore often a flight can go faster than the planners assumed. &lt;/p&gt;&#xA;" OwnerUserId="1792" LastEditorUserId="7532" LastEditDate="2016-05-03T16:21:25.737" LastActivityDate="2016-05-03T16:21:25.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27335" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T15:36:15.697" Score="6" Body="&lt;p&gt;&quot;Block&quot; times are most often padded to cover any delays like this. &lt;a href=&quot;http://www.flightstats.com/company/what-is-block-time-in-an-airline-schedule-and-why-does-it-matter/&quot; rel=&quot;nofollow&quot;&gt;FlightStats&lt;/a&gt; has a good explanation of what goes into calculating block times.  The short version is that carriers publish the &quot;quoted&quot; time it takes to go from block-to-block.  Pushing back from the departure gate to pulling into the destination gate.  As shown in the FlightStats link, some quote a shorter duration for the same segment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the destination side, nobody ever complains that their flight landed early. Problems for the airlines that do this is that when a plane is on the ground, you're paying money to the port instead of making money flying the plane.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that not all airlines have the same trip duration listed for a given flight segment. This can be tough to determine because such overlap generally requires one end be a large hub, and on the East coast US, these large airports are often slot controlled. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Padding block times helps accommodate WX (Weather), headwinds, tailwinds, etc. All at the expense of $$$. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;h2&gt;Further Reading:&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Interesting info on actual performance vs. Airlines published block times:  &lt;a href=&quot;http://projects.fivethirtyeight.com/flights/&quot; rel=&quot;nofollow&quot;&gt;http://projects.fivethirtyeight.com/flights/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also background on how that infographic is built and what factors into the decisions: &lt;a href=&quot;http://fivethirtyeight.com/features/how-we-found-the-fastest-flights/&quot; rel=&quot;nofollow&quot;&gt;http://fivethirtyeight.com/features/how-we-found-the-fastest-flights/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="11482" LastEditorUserId="11482" LastEditDate="2016-05-03T22:11:26.353" LastActivityDate="2016-05-03T22:11:26.353" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27336" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T16:50:51.020" Score="39" Body="&lt;p&gt;That's a common scenario, that you're pushing off the gate late and would like to make up time.  There are a number of ways that making up time can happen, although how much of that the pilot can affect doesn't often amount to a huge impact.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flight is scheduled for whatever length of time, gate-to-gate.  This accounts for the sorts of delays that the planners foresee when they're building the schedule: it's winter, so the aircraft may need to be de-iced.  It's a busy time of day, so they plan on a slower taxi than simply driving out to the runway &amp;amp; taking off.  The flight is usually scheduled around a moderately worst-case headwind/(lack of) tailwind.  And so for the 1+00 (in the air) flight, you might be scheduled for 1+30 gate-to-gate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And if some of the negative factors don't materialize, then you'll under-fly the schedule, which is nice.  Maybe the delay at the gate caused you to miss the &quot;morning rush hour&quot; and you &lt;em&gt;did&lt;/em&gt; get to taxi right out, no line or delay, and take off.  There's no precipitation, so no delay for de-icing.  The tailwinds are better than average today, so instead of 1+00, your flight will only be 0+55 in the air.  All good things!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But none of that is really under the pilot's control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The two places that the pilot can most affect things are, going faster, and getting shortcuts.  Going faster essentially means using more gas, and sometimes guys are willing to do that... the high-school tour group is in danger of missing their connecting flight &amp;amp; being stranded in the hub for the night, let's go fast &amp;amp; get them there!  Another version of going fast is flying at a more &quot;speed efficient&quot; altitude, usually around FL290 or FL300.  If winds are all the same, you'll generally get more speed there because your maximum indicated airspeed (Vmo) and limiting Mach number (Mmo) are very close around that altitude.  The tradeoff is, however, that you are burning more gas by doing this compared to going higher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you have the gas to burn, this can typically work.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, you can request shortcuts.  Depending on the filed route and what's going on in the airspace, this may get significant savings.  From the West Coast to DFW or IAH, you're typically routed around the north or south side of White Sands.  But, if it's Saturday night and the restricted area is cold (not in use), then you may be cleared direct right through it &amp;amp; save some significant time.  Of course, requesting shortcuts also saves gas (unless it takes you off a wind-optimized route -- rare but possible), so there's no real reason not to do it on every leg.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;ATC may or may not cooperate with your plans.  If the restricted area is hot, then you don't get the shortcut through it.  If you're inbound to a busy terminal area (DFW, LAX, IAH, BOS, etc) then ATC probably has a sequence in mind, and they won't approve anything that changes the orderly flow of aircraft into the arrival.  In fact, they may assign you a speed in order to fit the sequence together.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other than that sort of planning, though, they typically don't mind if you fly fast, and if they aren't too busy, ATC usually approves requests for shortcuts that don't have you driving through restricted areas (or other special use airspace).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much time can you make up as a pilot?  If you &lt;strong&gt;&lt;em&gt;really&lt;/em&gt;&lt;/strong&gt; want to burn the gas, you might make up 5-10 minutes by going fast on a typical 1-2 hour flight, but those extra minutes are getting pretty expensive when you do that.  Shortcuts may give you another 5 minutes or so, in the best case.  (Longer flights tend to be more direct, as a % of the time, so you can't get the bigger &amp;amp; bigger time savings on the longer flights with shortcuts as you do with speed, compared to the short flights.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But when a pilot tells you that he's going to make up 20 minutes off the planned flying time, most of that will probably be already baked in (tailwinds, no delays, etc) rather than things that he's doing differently than he otherwise would.  (It's still a nice line on the PA, though.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And some days, none of the above works the way you hope, and the late flight doesn't get any earlier, or even gets later, despite your best efforts.  Speed, time, and distance can just be a bear, sometimes! &lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-03T16:50:51.020" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27337" PostTypeId="2" ParentId="27263" CreationDate="2016-05-03T18:10:56.033" Score="3" Body="&lt;p&gt;A flameout is defined as a loss of engine power that is not caused by a mechanical failure. The three items needed to keep a jet engine operating are fuel, air, and a source of heat to make them burn. Loss of any one of these three can result in a flameout.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically if the temperature in the combustion chamber gets too low you get a flameout. But the engine's controller detects lowering temperatures (due to the rain or ice ingestion) very quickly and adds more fuel to compensate for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are (old) aircraft which have used water injection to increase engine performance, usually for take-off or engine failures, where it is needed the most. The reason the thrust is increased is because more mass (the water) is accelerated, but also that the temperature of the hottest section of the engine decreases, sod you can then add even more fuel to get a higher thrust without cooking the engines. If you add water to an oil based fire, it just explodes - a similar kind of energy is in play here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even in a strong storm, however, the main consequence of water ingestion a jet engine experiences is a reduction in the efficiency of the combustion process. This efficiency is a function of the fuel-air ratio that is changed by the presence of water vapor. This effect is negligible under most conditions since the percentage of water present in the large volume of air entering an engine is still relatively small in most storms. The high temperature in the engine's combustion chamber quickly evaporates this level of water into steam that has little influence on the engine's power output.&lt;/p&gt;&#xA;" OwnerUserId="14761" LastEditorUserId="5517" LastEditDate="2016-05-03T20:01:21.257" LastActivityDate="2016-05-03T20:01:21.257" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27338" PostTypeId="2" ParentId="27328" CreationDate="2016-05-03T19:12:57.343" Score="1" Body="&lt;p&gt;I am not a ATP, but I would be surprised if commercial flights went faster to make up time, even if they were delayed. The reason for this is that it is much more expensive because you burn fuel faster. To go at top speeds it is not a linear relationship and you could spend a lot of money to get a marginally faster time of arrival.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One free way to increase speed is to take advantage of winds at altitude. So, for example, if there are known to be favorable winds at 40,000 feet, you increase altitude to that level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You do not need &quot;permission&quot; to go faster. The pilots are the bosses and ATC are the servants, not the other way around. If a pilot wants to go faster, he goes faster, and notifies ATC of the change and they adjust what they have to.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-03T19:12:57.343" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27340" PostTypeId="2" ParentId="27321" CreationDate="2016-05-03T20:01:13.353" Score="8" Body="&lt;p&gt;Camber pushes the lift coefficient operating range up and increases the pitching moment of an airfoil. It is advised to use lots of camber if you need to create lots of lift at low speed and have no need to fly fast. Conversely, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow noreferrer&quot;&gt;high speed aircraft&lt;/a&gt; use uncambered wings. &lt;a href=&quot;https://aviation.stackexchange.com/questions/13584/why-do-airfoils-trailing-edges-point-downward/13597?s=1%7C0.0572#13597&quot;&gt;Flaps add camber&lt;/a&gt; - this makes them so effective for lowering the minimum speed of heavy aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/iqGIB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/iqGIB.png&quot; alt=&quot;Comparison of the same baseline airfoil at different camber values&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Comparison of the same baseline airfoil at different camber values (picture &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1945/naca-report-824.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). This is taken from &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1945/naca-report-824.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA Report 824&lt;/a&gt; which later was turned into one of the most important books for aerodynamicists.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wing thickness helps to build a lighter wing but will increase friction drag due to higher supervelocities caused by the displacement effect of the thick wing and cause earlier flow separation because the boundary layer is more stressed. In the end, you need to find a compromise: A 15% - 16% thickness is quite normal for GA aircraft, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Davis_wing&quot; rel=&quot;nofollow noreferrer&quot;&gt;high aspect ratio wings&lt;/a&gt; like those of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Consolidated_B-24_Liberator&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-24&lt;/a&gt; and the &lt;a href=&quot;http://airfoiltools.com/airfoil/details?airfoil=b29root-il&quot; rel=&quot;nofollow noreferrer&quot;&gt;B-29&lt;/a&gt; had a root thickness of  22%, but tapered the thickness down towards the outer wing as soon as practical. The tip thickness of both was just 9%.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The maximum lift will peak around 12% to 15% relative thickness. Below I copied figure 85 from &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1933/naca-report-460.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;NACA Report 460&lt;/a&gt; to illustrate the point:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Pk4Ec.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Pk4Ec.gif&quot; alt=&quot;Variation of maximum lift coefficient with airfoil thickness&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now this was all subsonic aerodynamics. Once you move closer to the speed of sound, the supervelocities can cause &lt;a href=&quot;https://aviation.stackexchange.com/questions/5048/why-does-supersonic-flight-detach-airflow-from-a-wing/5055?s=7%7C0.1486#5055&quot;&gt;pockets of supersonic air&lt;/a&gt; which end in a local shock. Therefore, the optimum thickness is reduced as the cruise speed approaches Mach 1, and wing sweep is added to cheat a little and keep thickness higher. Modern &lt;a href=&quot;https://aviation.stackexchange.com/questions/19016/could-airliners-wings-be-thinner-if-no-fuel-were-stored-in-them&quot;&gt;airliners use airfoils of around 13% relative thickness&lt;/a&gt;, and supersonic wings rarely use more than 6% relative thickness at the root, tapering to 2% to 3% at the tip.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2019-08-13T16:39:09.923" LastActivityDate="2019-08-13T16:39:09.923" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27341" PostTypeId="1" CreationDate="2016-05-03T20:22:11.553" Score="5" ViewCount="1961" Body="&lt;p&gt;On flights of a regular nature to set destination airports, I assume that there is a system is in place between airlines and airports/providers to pay invoices for fuel/services. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What do airlines do if diverted to an airport that the airline never normally serves or a freight airline doing a one-off flight to an airport? How do they pay? Does the captain carry a company credit card to pay for these one off charges?&lt;/p&gt;&#xA;" OwnerUserId="14762" LastEditorUserId="595" LastEditDate="2016-05-03T20:31:09.857" LastActivityDate="2016-05-04T02:34:49.697" Title="How do airlines pay for aviation fuel and services at an airport they don't normally use?" Tags="&lt;airline-operations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27342" PostTypeId="2" ParentId="27300" CreationDate="2016-05-03T20:49:13.163" Score="0" Body="&lt;p&gt;I guess both the propeller and the fan act in the principle of conservation of momentum, call it 'action-reaction', it send backwards a mass of air that pushes the device forward, the speed of expelled air mass, and the airspeed of airplane have an influence on which type of propulsive method gives better results, a lot of air at a not very high speed, or a lesser mass of air expelled very fast.&#xA;German engineers during WW II thought that propellers would be good up to a bit above Mach 1, but the contra-rotating propellers version of the F-84 Thunderstreak jet fighter proved so noisy that those close to the running engine or airstrip got sick. Here is a brief YouTube audio recording of the F-84H 'Thunderscreech':&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/YItexQxJS9U?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may like the attached chart, from the booklet: 'Ducted Fans for Ultralight Aircraft', by R. W. Hovey. It shows the efficiency of different propulsion systems according to AirSpeed of a flying machine. &#xA;&lt;a href=&quot;https://i.stack.imgur.com/euBl1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Typical Propulsion systems efficiency&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's a more detailed analysis of the subject in a 2009 Thesis by Leighton Montgomery Myers, Pennsylvania State University: 'Aerodynamic Experiments on a Ducted Fan in Hover and Edgewise Flight' &lt;a href=&quot;http://www.engr.psu.edu/rcoe/theses/Myers_Leighton.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://www.engr.psu.edu/rcoe/theses/Myers_Leighton.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also: AIAA-98-3116 NASA / TM--1998-208411 &#xA;General Aviation Light Aircraft Propulsion: From the 1940's to the Next Century Leo A. Burkardt Lewis Research Center, Cleveland, Ohio&#xA;Prepared for the 34th Joint Propulsion Conference cosponsored by AIAA, ASME, SAE, and ASEE Cleveland, Ohio, July 12-15, 1998 National Aeronautics and&#xA;Space Administration Lewis Research Center, July 1998. &#xA;&lt;a href=&quot;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980209647.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980209647.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3424" LastEditorUserId="5517" LastEditDate="2016-05-04T16:17:41.307" LastActivityDate="2016-05-04T16:17:41.307" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27343" PostTypeId="2" ParentId="27341" CreationDate="2016-05-03T21:01:42.093" Score="4" Body="&lt;p&gt;In the United States most places take credit cards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large carriers generally get billed, or for smaller airports they use a company credit card. There are even specialized credit cards that are designed specifically for this use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is also what is called &quot;contract fuel&quot;. Basically there is a company that is a middleman, a fuel supplier who pays the airport fuel company and then rebills the airline. The pilot has a card that identifies them as a client of the fuel contractor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, check out &lt;a href=&quot;http://aegfuels.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AEG Fuels&lt;/a&gt;, a typical fuel contractor. (Please click on that link. I get 25 cents every time you do. Just kidding.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0wzeV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0wzeV.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-05-04T02:34:49.697" LastActivityDate="2016-05-04T02:34:49.697" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27344" PostTypeId="1" CreationDate="2016-05-03T21:04:32.153" Score="8" ViewCount="377" Body="&lt;p&gt;Has a Tu-95 Bear bomber ever made an emergency landing in a European country while the flight was on a mission to test the country's defences?&lt;/p&gt;&#xA;" OwnerUserId="14762" LastEditorUserId="5517" LastEditDate="2017-10-05T14:41:23.493" LastActivityDate="2017-10-05T14:41:23.493" Title="Has a Russian Tu-95 ever had to make an emergency landing in Europe?" Tags="&lt;military&gt;&lt;tupolev&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="27345" PostTypeId="1" CreationDate="2016-05-03T21:18:32.110" Score="28" ViewCount="21673" Body="&lt;p&gt;The AOPA website lists four medications as acceptable treatments for depression. I was treated with one of them, but it ended up making things far worse, to the point where I had issues with suicidal ideation. I've since stopped taking it and, while I'm still somewhat depressed, no longer have those thoughts, and don't have any issues getting along with daily life.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My depression is more along the melancholic lines, so I basically just don't find most things enjoyable. Being in the air is one of the few things that helps, so obviously I'm worried about not being able to do so. I don't have any of the symptoms that would seem to have an impact on actually flying, but I know having a history is a problem, so I've been trying to figure out how much this will affect things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure if aircraft type matters for medical requirements, but I was hoping to either fly helicopters commercially, or in the very likely case that I can't find a helo school, I'd probably end up crop dusting.&lt;/p&gt;&#xA;" OwnerUserId="14767" LastEditorUserId="790" LastEditDate="2016-05-03T22:27:08.510" LastActivityDate="2016-05-10T20:13:54.963" Title="Will having a history of depression prevent me from flying?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;medical&gt;" AnswerCount="3" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27346" PostTypeId="2" ParentId="27345" CreationDate="2016-05-03T22:53:34.563" Score="25" Body="&lt;p&gt;This is one of those questions where you really need to talk to an AME, preferably one who has significant experience working through these sorts of issues.  In order to get the Class II medical that you'll need to fly commercially, you'll end up needing to work through the process anyway, so you're probably better off &lt;em&gt;starting&lt;/em&gt; with the expert, rather than with a message board like this one.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only case where you'd save any money by starting here is if someone here were to &lt;em&gt;accurately&lt;/em&gt; tell you that there is no need to go to an AME as there is no way anything could possibly work.  I doubt you're going to get that sort of advice, because (a) we don't have any AME's that post here on av.se, as far as anybody has ever self-identified, at least, and (b) this stuff is sufficiently complicated that you don't want to trust a layman's info or opinions, even one who &quot;knew somebody who had a similar situation.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That said, I'd suspect that the chances are pretty good that you may well be able to get a medical certificate, so I would encourage you to pursue that path.  Let a good AME take a look at the specifics of what your history looks like, and listen to his/her advice about what would need to happen (maybe very little, maybe quite a bit) in order to satisfy the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/26476/how-do-i-get-permission-to-fly-when-diagnosed-with-sleep-apnea/&quot;&gt;This thread&lt;/a&gt; deals with an entirely different medical condition, but the answers, and the logic behind them, apply here as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Be honest with the flight surgeon, and don't let random posters here talk you out of giving yourself every opportunity to pursue your dream of flying commercially.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Best of luck to you!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-03T22:58:57.697" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27347" PostTypeId="2" ParentId="27345" CreationDate="2016-05-03T23:58:53.930" Score="9" Body="&lt;p&gt;This is what the medical certification standards for third class say. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second class's standards text in the &quot;mental&quot; section is verbatim to third class standards.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§ 67.307 Mental.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Mental standards for a third-class airman medical certificate are: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) No established medical history or clinical diagnosis of any of the&#xA;  following: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) A personality disorder that is severe enough to have repeatedly&#xA;  manifested itself by overt acts.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) A psychosis. As used in this section, “psychosis” refers to a&#xA;  mental disorder in which— (i) The individual has manifested delusions,&#xA;  hallucinations, grossly bizarreor disorganized behavior, or other&#xA;  commonly accepted symptoms of this condition; or (ii) The individual&#xA;  may reasonably be expected to manifest delusions, hallucinations,&#xA;  grossly bizarre or disorganized behavior, or other commonly accepted&#xA;  symptoms of this condition. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) A bipolar disorder.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;...[stuff about drug and alcohol abuse truncated]...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) No other personality disorder, neurosis, or other mental condition&#xA;  that the Federal Air Surgeon, based on the case history and&#xA;  appropriate, qualified medical judgment relating to the condition&#xA;  involved, finds— (1) Makes the person unable to safely perform the&#xA;  duties or exercise the privileges of the airman certificate applied&#xA;  for or held; or (2) May reasonably be expected, for the maximum&#xA;  duration of the airman medical certificate applied for or held, to&#xA;  make the person unable to perform those duties or exercise those&#xA;  privileges.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If a medical is denied the FAA can choose to make exceptions.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;§67.315   Discretionary issuance.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A person who does not meet the provisions of §§67.303 through 67.313&#xA;  may apply for the discretionary issuance of a certificate under&#xA;  §67.401.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a6e8d117db3c3d1befb14b49baad49ac&amp;amp;mc=true&amp;amp;node=se14.2.67_1401&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;Here is a link to §67.401&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My personal opinion on the matter is that you will probably be able to get a medical and you may have a couple of extra hoops to jump through.  I'd think the fact that you've proven to be stable and aren't on medication will help you.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-04T05:21:34.377" LastActivityDate="2016-05-04T05:21:34.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27348" PostTypeId="1" CreationDate="2016-05-04T00:51:37.680" Score="12" ViewCount="1594" Body="&lt;p&gt;How much separation is required after an aircraft lands before ATC can clear another aircraft to take off from the same runway? On longer runways are small aircraft allowed to commence take off roll or be cleared for take off while the preceding landing aircraft is still on the runway? I looked and was unable to find any ATC instruction requiring separation between landing and departing traffic on the same runway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this would be unsafe, it seems to me that I have been cleared to take off while there was still an aircraft finishing its landing roll. By the time I had lined up for take off the preceding traffic is alway clear but is this still a &quot;legal&quot; practice to be cleared for take off before the preceding air craft calls &quot;clear of the active&quot; &lt;/p&gt;&#xA;" OwnerUserId="14667" LastEditorUserId="14667" LastEditDate="2016-05-04T01:32:25.800" LastActivityDate="2016-05-04T16:07:52.543" Title="Can tower clear aircraft for take off with traffic still on the runway?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;air-traffic-control&gt;&lt;far-91&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27349" PostTypeId="1" AcceptedAnswerId="27356" CreationDate="2016-05-04T00:58:01.297" Score="10" ViewCount="347" Body="&lt;p&gt;The fan blades in a fanjet are mounted loosely in a fir-tree shaped mount so they are free to lead or lag and balance themselves. The blades on fully articulated and semi-rigid helicopter rotor heads are mounted with a drag hinge that allows them to lead/lag as needed. Do any propeller aircraft have a method to allow the blades to lead/lag, or is this for some reason unnecessary?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-05-05T04:56:56.807" Title="Do propellers have any lead/lag mechanism?" Tags="&lt;propeller&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27350" PostTypeId="2" ParentId="27348" CreationDate="2016-05-04T01:54:53.683" Score="6" Body="&lt;p&gt;All references for this answer are in the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;nofollow&quot;&gt;FAA Order 7110.65&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A departure cannot start their takeoff roll before the previous arrival has cleared the runway. What most controllers will do, is use a provision for anticipated separation (3-9-5), which basically means, if someone's holding short, and you can predict when the arrival will exit, you can go ahead and issue the take-off clearance. The controller will keep an eye on things, and if it looks like it won't work, or something's changed, the pilot of the departure will be told something along the lines of: &quot;[Callsign], cancel takeoff clearance, runway [x] line up and wait, traffic exiting downfield&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can 2 or more aircraft be on the runway at the same time for the same type of action? Yes, in a few cases. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Between 2 arrivals, during daylight, small single engine propeller driven aircraft, and small twin engine propeller driven aircraft weighing less than 12,500, as long as the lead aircraft is at least 3000, or 4500 feet down the runway, the next can continue and land. &lt;/li&gt;&#xA;&lt;li&gt;Also departures, depending on type, the as long as separation exists, 3000, 4500, or 6000 feet and airborne between departures is all that's needed under normal situations. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All the full details can be found in Chapter 3, Sections 9, 10 of the 7110.65.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastEditorUserId="5517" LastEditDate="2016-05-04T16:07:52.543" LastActivityDate="2016-05-04T16:07:52.543" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27351" PostTypeId="2" ParentId="27348" CreationDate="2016-05-04T01:57:29.830" Score="13" Body="&lt;p&gt;According to &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;the ATC orders&lt;/a&gt; controllers can indeed clear an aircraft for takeoff 'early':&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;3−9−5. ANTICIPATING SEPARATION&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Takeoff clearance needs [&lt;em&gt;sic&lt;/em&gt;] not be withheld until prescribed separation&#xA;  exists if there is a reasonable assurance it will exist when the&#xA;  aircraft starts [&lt;em&gt;sic&lt;/em&gt;] takeoff roll.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;A common scenario would be clearing an aircraft that's holding off the runway to take off while the landing aircraft is still on the runway. If the controller expects that the landing aircraft will be off the runway by the time the holding one turns onto it, then it would be allowed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 3-9-6 lists the conditions for allowing an aircraft to start its takeoff roll. It's too long to quote here and you can read it yourself but the two main  conditions seem to be:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The other aircraft has departed and crossed the runway end or turned to avert any conflict&lt;/li&gt;&#xA;&lt;li&gt;A preceding landing aircraft is clear of the runway&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-04T01:57:29.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27352" PostTypeId="2" ParentId="27293" CreationDate="2016-05-04T03:15:01.217" Score="9" Body="&lt;p&gt;As listed on a CNI-MU emulator designed for use by C-130J loadmasters, the following is a list loads and moment arms for the aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Basic weight: 80,000 lbf/STA 530 &lt;/li&gt;&#xA;&lt;li&gt;Crew weight: 600 lbf/STA 153&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fuel weight: 38,000 lbf/STA 551 -- this weight is, naturally, variable,&#xA;although the moment arm appears to stay relatively constant.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;CG limits: 21-30% MAC&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Finally, payload moment arms can be determined via use of of DD form 2130-2 on page III-V-17 of the 2015 Defense Transport Regulations (&lt;a href=&quot;http://www.ustranscom.mil/dtr/part-iii/dtr_part_iii_app_v.pdf&quot; rel=&quot;noreferrer&quot;&gt;http://www.ustranscom.mil/dtr/part-iii/dtr_part_iii_app_v.pdf&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="14720" LastEditorUserId="19" LastEditDate="2016-06-23T14:37:40.853" LastActivityDate="2016-06-23T14:37:40.853" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27353" PostTypeId="2" ParentId="27345" CreationDate="2016-05-04T04:25:36.397" Score="16" Body="&lt;p&gt;I have a history of depression and hold a 3rd class medical certificate.  In my case the depression is managed by medication so the certificate is issued under what is called a Special Issuance (SI).  Therefore I have personal experience with the extra &quot;hoops&quot; involved that others have mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You must start with a consultation with a HIMS (Human Intervention Motivation Study) AME.  These doctors have additional training and familiarity with the depression and anti-depressant SI protocol introduced in 2010.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The AME who moderates the AOPA medical issues forum is an excellent starting point (he helped write the protocol that the FAA adopted) and you can contact him directly for advice.  Alternatively you can find a HIMS AME in your local area by consulting the FAA's &lt;a href=&quot;http://www.faa.gov/pilots/amelocator/media/HIMS%20INDEPENDENT%20MEDICAL%20SPONSORS.pdf&quot;&gt;official list&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Good luck!&lt;/p&gt;&#xA;" OwnerUserId="386" LastActivityDate="2016-05-04T04:25:36.397" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27354" PostTypeId="2" ParentId="8805" CreationDate="2016-05-04T05:06:01.247" Score="16" Body="&lt;p&gt;Hi guys few days ago a twin otter did make an aborted landing and made a &quot;go around&quot; at the airport and headed back to Kathmandu. This is the first time such an incident happened although there has been numerous crashes in the past. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a link to the video.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/8LD5JhGMxow?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="14771" LastActivityDate="2016-05-04T05:06:01.247" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27355" PostTypeId="1" AcceptedAnswerId="27362" CreationDate="2016-05-04T06:47:53.843" Score="15" ViewCount="1631" Body="&lt;p&gt;My understanding of trim:&#xA;When you say you have trimmed an aircraft for a constant speed, say 100 mph, you are actually trimming the horizontal stabilizer so that there are no forces on stick (or tail down force is balanced with nose weight) at that speed. To do that you either control the horizontal stabilizer/trim tabs until no force is felt on the stick. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is, (if my understanding is right), can I say that we are trimming for constant angle of attack instead of speed (and the constant angle of attack is represented in form of speed). By trimming the aircraft, aren't we making the aircraft fly  at constant angle of attack?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, can I make these following statements about trim: (ignoring the things like propeller blast etc..,)&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;When you are cruising in a trimmed condition and decrease( or increase) the engine power, the aircraft will pitch down (or up) until it finds the old angle of attack where all the forces are balanced and the trim is reestablished. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When you are cruising and closed (or opened) the throttle completely, the aircraft will descent (or climb) at the same trimmed angle of attack.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="15982" LastEditDate="2018-05-07T11:54:20.683" LastActivityDate="2021-05-15T21:49:16.797" Title="Is trimming for constant speed equal to trimming for constant angle of attack?" Tags="&lt;engine&gt;&lt;airspeed&gt;&lt;trim&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27356" PostTypeId="2" ParentId="27349" CreationDate="2016-05-04T06:51:49.707" Score="9" Body="&lt;p&gt;The two things are completely different and exist for different reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Fan and turbine blades are mounted loosely, so they can self-balance. This is because at the very high RPM fans and turbines spin at they are extremely sensitive to imbalance. On the other hand, the self-balancing only works at high RPM. It also requires the blades to be connected at the tips with the “shroud”.&lt;/li&gt;&#xA;&lt;li&gt;Rotors have lead-lag hinges because the rotor spins parallel to the flow so in forward flight the advancing blade  meets the air at significantly higher speed than the retreating blade.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Propellers spin slower, so they are not as sensitive to imbalance, and they don't have the shroud, so they can't be mounted loosely anyway. They spin perpendicular to the airflow, so all blades meet the air at similar speed and angle of attack, so they don't need to deal with as big differences in the aerodynamic forces. And they are smaller and more rigid.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="13666" LastEditDate="2016-05-05T04:56:56.807" LastActivityDate="2016-05-05T04:56:56.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27357" PostTypeId="1" AcceptedAnswerId="27368" CreationDate="2016-05-04T07:20:39.937" Score="7" ViewCount="250" Body="&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/about/media/b-chron.pdf&quot; rel=&quot;nofollow&quot;&gt;This is a history of the FAA from their site.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the U.S., we had the original set of aviation laws known as aeronautical bulletins back in the 1920's and 1930's. Later (in 1938) we had the Civil Aviation Regulations (CARs), created by the Civil Aeronautics Authority (CAA), added to them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am curious if those laws were actually repealed or simply made redundant by today's regulations and whether or not there were additional laws not seen in the FARs today but which did exist in the CARs and Aeronautical Bulletins.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="938" LastEditDate="2016-05-04T23:07:31.507" LastActivityDate="2016-05-08T14:43:57.437" Title="Do &quot;Civil Aviation Regulations&quot; and &quot;Aeronautics Bulletins&quot; still have any legal authority today?" Tags="&lt;faa-regulations&gt;&lt;aviation-history&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27358" PostTypeId="2" ParentId="27357" CreationDate="2016-05-04T07:20:39.937" Score="6" Body="&lt;p&gt;No, except for a type certification rule.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aug 23, 1958: &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;President Eisenhower signed the Federal Aviation Act of 1958 (P.L.&#xA;  85-726) into law. Treating comprehensively the Federal role in&#xA;  fostering and regulating civil aeronautics and air commerce, the new&#xA;  statute repealed the Air Commerce Act of 1926, the Civil Aeronautics&#xA;  Act of 1938, the Airways Modernization Act of 1957, and those portions&#xA;  of the various Presidential reorganization plans dealing with civil&#xA;  aviation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The aviation law slate was wiped clean and started fresh with the FAA, although many of the principles in the aeronautical bulletins and the Civil Aviation Regulations were clearly incorporated into the FARs we know today.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-08T14:43:57.437" LastActivityDate="2016-05-08T14:43:57.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27359" PostTypeId="2" ParentId="27355" CreationDate="2016-05-04T07:44:11.770" Score="-1" Body="&lt;p&gt;This is an interesting question. I believe that both of your statements are wrong though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Trimming for constant speed&quot; is technically not possible, as the trim itself has nothing to do with the speed. As you probably know, you have to adjust both throttle and trim to have the plane fly level at a constant speed. Trim only controls your elevator (neglecting the other two trims that larger aircraft usually have as well). When you &quot;trim for constant speed&quot;, you usually adjust your power setting while keeping the plane flying at a certain altitude. Then (or even while you adjust your speed) you trim the plane to take work of your arms ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you're flying at a constant speed, you can say that the angle of attack remains the same when you're not descending/ascending. No comes the tricky part though:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You're saying that the aircraft will find a balanced condition again - which is right. Yet you have decreased the power, thus you've changed one force. Because of that, the other forces must change as well to balance each other out. The angle of attack will thus &lt;strong&gt;NOT&lt;/strong&gt; be the same when the throttle is different.&lt;/li&gt;&#xA;&lt;li&gt;Again, when closing the throttle, the aircraft will find a new balanced condition, and again, the angle of attack will change.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Another interesting question is: &lt;em&gt;When you are flying at a trimmed condition and decrease the throttle, then after a while increase it back to the original setting, will the aircraft return to level flight?&lt;/em&gt; - The answer is yes, but no ;) Yes, because now all forces are back to the original condition, thus the airplane must have the same attitude. No, because by descending, the air density will change, thus resistance of the air becomes bigger which enforces a bigger force or resistance on the plane messing up the balance again. &lt;/p&gt;&#xA;" OwnerUserId="5592" LastActivityDate="2016-05-04T07:44:11.770" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27361" PostTypeId="1" AcceptedAnswerId="27363" CreationDate="2016-05-04T08:17:00.337" Score="14" ViewCount="543" Body="&lt;p&gt;When ATC instructs me something like &quot;There is a Skyhawk on your 2 clock, 7 miles, 6500&quot;. I am not able to spot the target at least half of the time after several ATC reports its position until ATC says &quot;not a factor&quot; or gives me a new heading or altitude assignment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering if there is any effective ways to get the aircraft spotting skill? Or knows my limit that it is nearly impossible to see it if it beyond a certain range and give up searching. When entering busy airspaces, the aircraft looking is taking a large portion of cockpit time. &lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2017-01-29T12:31:22.353" Title="What are effective ways to spot the aircraft ATC specified?" Tags="&lt;air-traffic-control&gt;&lt;visual-flight-rules&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27362" PostTypeId="2" ParentId="27355" CreationDate="2016-05-04T08:38:16.770" Score="20" Body="&lt;h2&gt;Short answer: Yes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Generally you are right. You are trimming the aircraft for a point on its polar, and that point is reached at a specific angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You say yourself we should neglect secondary effects like the propeller blast, and under this condition you are right. Trimming means to set the distribution of lift between wing and tail surface, and this directly sets the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Now the more elaborate part of the answer&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;You trim the aircraft for a specific dynamic pressure, that is the product of air density and flight speed. If you slightly change your question from &quot;trimming for constant speed&quot; to &quot;trimming for constant indicated speed&quot;, you gain precision and the answer is still yes. With a change in altitude you will also &lt;a href=&quot;https://aviation.stackexchange.com/questions/24641/drag-as-a-function-of-altitude/24644?s=3%7C0.1426#24644&quot;&gt;affect the Reynolds number&lt;/a&gt; the aircraft flies at, and the same polar point is reached at a slightly higher angle of attack the lower the Reynolds number gets when the aircraft climbs into colder air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In turns the lift demand is increased. Not changing trim during a turn will let the aircraft speed up to increase lift at an unchanged angle of attack. That is why you pull more when turning - you want to increase the angle of attack, so speed can stay constant. When speeding up, you again change the Reynolds number and indirectly also the angle of attack, but this effect is very small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you change the power setting, you &lt;a href=&quot;https://aviation.stackexchange.com/questions/12096/what-is-the-relationship-between-power-and-fuel-efficiency/12107?s=1%7C0.1048#12107&quot;&gt;add energy to the aircraft&lt;/a&gt; at a different rate. Thrust becomes bigger and is counteracted by the sum of drag and the component of weight which acts in parallel to the thrust vector. Now &lt;a href=&quot;https://aviation.stackexchange.com/questions/12714/why-do-airplanes-lift-up-their-nose-to-climb/12720?s=1%7C0.2553#12720&quot;&gt;the vertical component of weight is reduced&lt;/a&gt;, and so is your need for lift - but ever so slightly. This effect by itself means you will fly at a slightly smaller speed which will also very slightly affect the angle of attack. But since you did not change trim, the distribution of lift between wing and tail is unchanged, so the angle of attack is the same, save for a minuscule Reynolds number effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Increasing thrust will also increase the prop blast over the tail surfaces, making them more effective and slightly changing the balance of the aircraft. Depending on the direction of tail lift, the result is an increase or a decrease in angle of attack, but this is precisely the effect you wanted us to disregard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another secondary effect is a constant loss of weight as the engine burns fuel. This makes the aircraft lighter, so it requires less lift and a smaller angle of attack over time to remain at the same speed. Since you trimmed a specific polar point, the aircraft would need to slow down in order to stay at this polar point at its lower weight. But the lower weight also creates less drag, so instead of slowing down the aircraft will climb. Now the reduced density will require more angle of attack and will reduce engine output so in the end the same angle of attack is maintained at a higher altitude but a slightly lower indicated airspeed.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-05-07T22:30:35.940" LastActivityDate="2018-05-07T22:30:35.940" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="27363" PostTypeId="2" ParentId="27361" CreationDate="2016-05-04T10:25:08.183" Score="8" Body="&lt;p&gt;(Daytime flying only. Peripheral and night vision is different and I have zero practice of night flying.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The highest resolution part of the eye is the fovea, and it's surprisingly narrow. If a small, slow-moving object is outside this area it probably won't be seen. If you scan from say 20 degrees left of an object to 20 degrees right of it you will also miss, because the eye tends to jump in steps and we only see a small fraction of what is actually in front of us.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I was always told to gaze steadily, in ten degree steps, for a few seconds at each area. A grid of search areas both above and below the horizon should be checked. You'll only recognise an object when your fovea is virtually on it.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Only look for a second or two at each are because any longer and the vision &quot;bleaches&quot; and you are even less likely to recognise anything in that region; just keep moving on to the next.&lt;/li&gt;&#xA;&lt;li&gt;The narrow 10 degree steps are that size because that's the region&#xA;of acceptably sharp vision. (I suspect it differs between individuals)&lt;/li&gt;&#xA;&lt;li&gt;This was what I was taught for general lookout, though I suppose it should apply to a specific search area given by ATC too.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Apparently these tips were all derived from RAF training for this sort of thing, but I don't have any notes on that.  In any case I suspect it's more practice than bookwork anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of my gliding instructors liked the spotting game. One point for every aircraft I spot before him. He had one dodgy eye and of course still won by an appalling margin... (I've also heard some play this game for beers, though frankly none of my instructors would ever be able to drive home.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastEditorUserId="8417" LastEditDate="2016-05-04T10:58:05.173" LastActivityDate="2016-05-04T10:58:05.173" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27364" PostTypeId="2" ParentId="27361" CreationDate="2016-05-04T12:19:05.877" Score="5" Body="&lt;p&gt;A lot of it is about disciplined scanning:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Don't move your head, move your eyes&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Scan up and down, left to right, like a lawnmower; be methodical&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;a difference of 1000 feet at 10 miles is about 1-degree, which is the angular diameter of the moon which is the width of 1 finger held at arm's length; so for example, if it is at 6500 7 miles away and you are at 4500, then it is about 3 moons/fingers above your horizon&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If you missing stuff, the most likely reason is that you are looking around randomly, instead of lawnmower scanning&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-04T12:19:05.877" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27365" PostTypeId="2" ParentId="27344" CreationDate="2016-05-04T12:28:49.803" Score="3" Body="&lt;p&gt;Not that anyone knows of. A couple of Bears have crashed within Russia's borders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They usually fly over international waters only, so if one did go down there would be a chance it would sink without a trace.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-04T12:28:49.803" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27367" PostTypeId="2" ParentId="5159" CreationDate="2016-05-04T16:55:12.507" Score="8" Body="&lt;p&gt;I asked my instructor and this was his answer!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Nefarious Skyhawk Gas Gremlin !&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fact: When a high wing plane (such as a Cessna 172 or a Cessna 150) is flown on a training flight with the fuel selector in the &quot;Both&quot; position (C150 fuel valves are always on the &quot;both&quot; position - even when &quot;off&quot;) with a primary flight student at the controls, the plane will almost always land with more fuel in the right tank than in the left (but the very same plane may occasionally land with more fuel in the left tank with a slightly more experienced student, or - eventually - with equally balanced fuel tanks).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Why is this?&quot; you ask.  &quot;How can this be?&quot; you demand to know!  I ask all my students this, but I try not to give them the answer.  The answer is completely obvious once they have flown for a while.  Once they understand the most fundamental basics of flight, they will be able to tell me the secret of &quot;The Nefarious Skyhawk Gas Gremlin&quot;.  (But once in a while a CFI is compelled to point out the obvious).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;WHAT IT IS NOT:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not because of a design flaw in the Cessna.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not because of an obstruction in the fuel line or the vent (while that is possible, this rare obstruction problem is not germane to the nearly universal &quot;Gas Gremlin&quot; phenomenon).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not because of turns and banks during flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An aircraft can do steep turns all day long; loops, wing-overs, and barrel rolls, ad infinitum, with the fuel selector in the &quot;both&quot; position, and never have a fuel imbalance.  Yet a simple training flight will usually result in more fuel in the right tank than the left.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;WHAT IS THE CAUSE?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hint, the answer is related to the &quot;native call of the CFI in his/her natural environment&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cause is revealed, not by the trusty aircraft mechanic, nor by the psychic aviation consultant, but by the most simple indicator found in all airplanes: The slip/skid ball.  The force that causes the ball to be pulled to the right side of the curved glass tube during takeoff, climb, and power-on stall practice, is the very same force that is pulling the fuel from the left tank into the right wing tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is also the origin of the &quot;native call of the CFI in his/her natural environment&quot; ...  &quot;RIGHT RUDDER!  RIGHT RUDDER!  RIGHT RUDDER!  ... STEP ON THE BALL !!!&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note: this unbalanced fuel condition will also be caused when even the most experienced pilot is practicing side-slips and forward slips.  But this is OK, and elicits only a silent smile from the CFI.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;JT Rairigh, CFII, MEI, Helicopter, A&amp;amp;P/IA&lt;/p&gt;&#xA;" OwnerUserId="14780" LastActivityDate="2016-05-04T16:55:12.507" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27368" PostTypeId="2" ParentId="27357" CreationDate="2016-05-04T17:13:29.317" Score="5" Body="&lt;p&gt;Many aircraft were certified to CAR standards.  Those aircraft still have to meet those standard.  Even a brand new aircraft off the line today, that is produced  based on a type certificate data sheet that has CAR regulations has to meet those regulations.   &lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2016-05-04T17:13:29.317" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27369" PostTypeId="1" CreationDate="2016-05-04T21:01:40.483" Score="11" ViewCount="479" Body="&lt;p&gt;Raymer tells (Source: Raymer: Aircraft Design – A Conceptual Approach Chapter &quot;5 THRUST-TO-WEIGHT RATIO AND WING LOADING&quot; Paragraph “5.3 WING LOADING” Subparagraph “Climb and Glide”) that, when the aircraft is climbing, if the climb angle γ is small,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;then $G=\frac{T-D}{W}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(G is Climb Gradient as defined by Raymer words: &quot;Rate of climb is vertical velocity,.. Climb gradient G is the ratio between vertical and horizontal distance traveled. This is approximately equal to the vertical climb rate divided by the aircraft velocity, or the sine of the climb angle γ.&quot; Source: Raymer: Aircraft Design – A Conceptual Approach Chapter &quot;17 PERFORMANCE AND FLIGHT MECHANICS&quot; Paragraph “17.3 STEADY CLIMBING AND DESCENDING FLIGHT” Subparagraph  “Climb Equations of Motion”)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then $\frac{D}{W}=\frac{T}{W}-G$   ( that is the first relation for D/W).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time  $D=q\cdot S\cdot c_{D0} + q\cdot S\cdot\frac{c_L^2}{π\cdot AR \cdot e}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And substituting $c_L=\frac{W}{q\cdot S}$,&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{D}{W}=\frac{q\cdot S\cdot c_{D0}+q\cdot S\cdot\frac{c_L^2}{π\cdot AR\cdot e}}{W}=\frac{q\cdot c_{D0}}{\frac{W}{S}}+\frac{W}{S}\cdot\frac{1}{q\cdot π\cdot AR\cdot e}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(that is the second relation for $\frac{D}{W}$)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Equating the first and the second relation and solving for wing loading,&#xA;we have:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{W}{S}=\frac{\left(\frac{T}{W}-G\right)± \sqrt {\left(\frac{T}{W}-G\right)^2-\frac{4\cdot c_{D0}}{π\cdot AR\cdot e}}}{\frac{2}{q\cdot π\cdot AR\cdot e}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MY FIRST QUESTION: In this equation are both, the bigger and the lower solution values for $\frac{W}{S}$ realistic for aircraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After,  Raymer notes that the term within the square root symbol in the equation above cannot fall below zero, so the following must be true regardless of the wing loading: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{T}{W}≥G+2\cdot\sqrt{\frac{c_{D0}}{π\cdot AR\cdot e}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MY SECOND QUESTION: Raymer doesn’t consider that there are two solutions sourcing from the condition that the term within the square root symbol cannot fall below zero, the other one is:   $$\frac{T}{W}≤G-2\cdot\sqrt{\frac{c_{D0}}{π\cdot AR\cdot e}}$$. Why shouldn’t be considered? Could the second solution represent something realistic?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I HAVE A SUPPLEMENTARY QUESTION:&#xA;Relating to my questions above, I have to report two comments Raymer writes immediately after the last equation and inequality.: &quot;This equation says that no matter how &quot;clean&quot; your design is, the T/W must be greater than the desired climb gradient! ....... Another implication of this equation is that a very &quot;clean&quot; aircraft that cruise at a high speed despite a very low T/W will probably climb poorly. A 200-mph airplane that flies on 20 hp can't be expected to climb as well as an airplane that requires 200 hp to reach 200 mph (unless the latter weighs ten times as much)&quot;&#xA;Could anyone explain me better the last sentences, in particular, in which case T/W is very low with high speed? If we have high speed doesn't T/W should be high too?&lt;/p&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="13498" LastEditDate="2016-05-05T16:32:44.560" LastActivityDate="2016-05-16T05:18:47.497" Title="About climb: If we use T/W as input, the second grade equation yields two solutions for W/S. Are both solutions realistic?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27372" PostTypeId="2" ParentId="25681" CreationDate="2016-05-04T22:25:00.167" Score="2" Body="&lt;p&gt;Thank you for the excellent question!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The whole expression is only valid for the optimum polar point where the ratio $\frac{c^2_D}{c^3_L}$ reaches its maximum. If you deflect spoilers, this optimum will shift to a higher lift coefficient, so both aircraft will not fly at the same lift coefficient or the same speed any more! Always keep in mind that &lt;strong&gt;in this special condition&lt;/strong&gt; the lift coefficient can also be expressed as &#xA;$$c_L=\sqrt{3\cdot\pi\cdot AR\cdot e\cdot c_{D0}}$$&#xA;Just plug that back into the equation and the minimum power expression will make a whole lot more sense:&#xA;$$P_{min}=\frac{4}{3\cdot\pi\cdot AR\cdot e}\cdot\sqrt{\frac{2\cdot W^3\cdot\sqrt{3\cdot\pi\cdot AR\cdot e\cdot c_{D0}}}{\rho\cdot S}}$$&#xA;This is still the same equation, but now it should be obvious that opening the spoilers will require more power.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-05T06:44:16.167" LastActivityDate="2016-05-05T06:44:16.167" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27373" PostTypeId="1" CreationDate="2016-05-04T22:40:51.423" Score="15" ViewCount="1532" Body="&lt;p&gt;Some time ago, I was on a commercial flight and while the airplane was taxiing around, there was this rhythmic bouncing. &lt;a href=&quot;https://www.youtube.com/watch?v=4utjBf6XnJQ&quot;&gt;Here&lt;/a&gt; is a video I made of the takeoff. You can notice the bouncing at the taxi and takeoff roll of the video. What causes that rhythmic bouncing? Is it a result of uneven wear on the tires?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the sake of anyone who wants to know in case it helps, the airplane was a Boeing 757-200.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-05-05T16:15:45.137" LastActivityDate="2016-05-05T18:08:36.837" Title="What causes an airplane to rhythmically bounce during taxiing?" Tags="&lt;landing-gear&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27374" PostTypeId="1" CreationDate="2016-05-04T23:00:06.997" Score="7" ViewCount="399" Body="&lt;p&gt;I recently saw a domestic tour operator using aircraft with foreign registry. The pilots had U.S. CPLs. Can foreign-registered aircraft operate commercially within the U.S.A, in an operation where flights begin and end within the U.S.A.?&lt;/p&gt;&#xA;" OwnerUserId="14782" LastEditorUserId="19" LastEditDate="2016-07-07T10:17:56.767" LastActivityDate="2016-07-07T10:17:56.767" Title="Is commercial domestic service using foreign registry aircraft allowed in the USA?" Tags="&lt;faa-regulations&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27375" PostTypeId="2" ParentId="27374" CreationDate="2016-05-05T02:07:10.610" Score="10" Body="&lt;p&gt;Yes, it's allowed under both part 135 (on-demand) and part 121 (airlines); &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=57fa7884e04214aba7f9e3cc9053ea51&amp;amp;mc=true&amp;amp;node=se14.3.121_1153&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;121.153&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=1a6df52e7a785d3cceb7f2bf28884677&amp;amp;mc=true&amp;amp;node=sp14.3.135.a&amp;amp;rgn=div6#se14.3.135_125&quot; rel=&quot;nofollow noreferrer&quot;&gt;135.25&lt;/a&gt; both have the same wording:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A certificate holder may operate in common carriage, and for the&#xA;  carriage of mail, a civil aircraft which is leased or chartered to it&#xA;  without crew and is registered in a country which is a party to the&#xA;  Convention on International Civil Aviation if— [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And US pilots &lt;a href=&quot;https://aviation.stackexchange.com/q/3667/62&quot;&gt;may fly foreign aircraft&lt;/a&gt; within the US.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-05-05T02:07:10.610" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27376" PostTypeId="2" ParentId="27263" CreationDate="2016-05-05T02:11:06.243" Score="12" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16841/how-are-temperature-differences-handled-in-a-jet-engine&quot;&gt;In another question&lt;/a&gt; there is an excellent answer for how thermal expansion is handled in a jet engine.  It's an established fact that jet engines can handle fast temperature swings.  Have you watched how fast an ITT gauge goes up when starting an engine? My answer will focus on rain's effect on a jet engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing to understand is that jet engines take a lot of air. That's why they can handle bizarrely heavy rainfall or even water on the runway splashing into the engine from the tires (this water jet has the fun name &quot;rooster tails&quot;). The Airbus 320, for example, goes through 27,000 liters of air every second during takeoff. &lt;a href=&quot;http://collaboration.cmc.ec.gc.ca/science/rpn/SEM/dossiers/2006/seminaires/2006-04-07/AirVolumes_CMOSBULLETINSCMO_latest.pdf%20[1]&quot; rel=&quot;nofollow noreferrer&quot;&gt;2&lt;/a&gt; That means even during rigorous FAA certification testing the concentration of water ingested never gets higher than 20 g of water for every cubic meter of air.  &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/part-33/appendix-B&quot; rel=&quot;nofollow noreferrer&quot;&gt;See FAA Part 33.78 Appendix B&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order for you to understand why the water has little cooling effect I have to describe what happens when an engine takes in water, assuming you know the basic parts of a jet engine.  The air/water mixture enters the compressor, and the fan blades in this compressor are spinning rapidly enough to catch a lot of the water and like a centrifuge this water is spun towards the walls.  This helps prevent water from entering the combustion path on a bypass engine, but it does not prevent water from following the gas path, especially on an engine with no bypass around the gas path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine must now adjust for the extra water in the air, and &lt;em&gt;engines are very good at adjusting for these kinds of changes in conditions&lt;/em&gt;.  If there's more than one independent compressor rotor, for example, the rotor speeds will change to keep the air moving smoothly and ensure a correct pressure drop across the compressor, called &quot;compressor rematching.&quot;  The engine will also increase the fuel to air ration to compensate for the water.  These two processes evaporate the extra water through thermodynamic heating, not through heat transfer.  In essence, the first stages of the engine are providing the extra energy to evaporate the water, so little differential cooling occurs, even if the amount of rain is rapid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One thing to note here is that the engine actually runs hotter than normal instead of cooler than normal during these events, due to the reasons noted above as well as &lt;a href=&quot;https://en.wikipedia.org/wiki/Water_injection_(engine)#Use_in_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;the extra thrust provided from the water injection.&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All the parameter changes noted above reduce your margins for engine flame out and compressor stall.  In practice, an engine should flame-out or surge before water can cause a big enough thermal change to cause engine damage.  If you think about it, the amount of temperature change needed to cause a problematic warping of an engine should be a lot more than the amount required to cause the engine to quit running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So we've established that &lt;a href=&quot;https://aviation.stackexchange.com/questions/16841/how-are-temperature-differences-handled-in-a-jet-engine&quot;&gt;jet engines are good at expanding and contracting due to thermal changes&lt;/a&gt;.  We've also established that relatively speaking we're actually not talking about a ton of water here, just a few grams per cubic meter of air, which would take a small percent of the engine power to evaporate (~1% by my calculations). Most of the extra water is evaporated not by cooling down engine parts, but by making the early stages of the engine work harder.  Finally, the reduced margins caused by water intake mean that you'll surge or flame-out before you get to warping engine parts.  These principles should apply regardless of whether the water ingestion begins in a matter of seconds or ramps up over several minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In conclusion, in &quot;Investigation of Engine Power Loss and Instability in Inclement Weather,&quot;&lt;a href=&quot;http://lessonslearned.faa.gov/SouthernAirways242/AIA_PC338.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;(pdf)&lt;/a&gt;  the FAA noted &quot;Engines typically are not damaged during a heavy rain encounter. Usually the most severe situation is to experience multiple engine flameout or surge with a subsequent pilot initiated engine shutdown.&quot;  The report then went on to note that the two incidents where engine damage had occurred from rain were over-temperature events, not from differential cooling.  So your biggest worry when flying through even storm-of-the-century rainfall should not be whether your engine will warp from rain cooling things down.&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-05-05T17:40:02.060" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27377" PostTypeId="1" CreationDate="2016-05-05T06:30:32.027" Score="-1" ViewCount="1243" Body="&lt;p&gt;According to regulations, what should a mini-drone do once it is out of the control range?  Would it continue flying even if it receives no signal? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about full size drones?&lt;/p&gt;&#xA;" OwnerUserId="14786" LastEditorUserId="12220" LastEditDate="2016-05-06T23:17:19.613" LastActivityDate="2016-05-09T19:06:23.690" Title="What does a drone do when it's out of control range?" Tags="&lt;faa-regulations&gt;&lt;easa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;&lt;security&gt;" AnswerCount="2" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27380" PostTypeId="2" ParentId="27373" CreationDate="2016-05-05T12:25:01.370" Score="5" Body="&lt;p&gt;That is caused because the wheels are &quot;uneven&quot; after the plane was waiting at the stand. You have to imagine, that a plane has an enormous weight. The wheel are not fully pressurized like in a car, because they are going to expand in higher elevation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, assuming an 44.5in (1.1m) tyre diameter (circumference ca 4m) and the taxying speed of approx. 17kts (ca 8m/s), we would hit the flat spot every ca 4 meters, so twice a second. That would induce oscillations. Im not a mechanical engineer, but i could imagine that this in combination with the dampers would cause the described vibrations. As the Boeing technical Guide is describing this as the cause I don't see any reason to doubt that.&lt;/p&gt;&#xA;" OwnerUserId="5588" LastEditorUserId="12220" LastEditDate="2016-05-05T18:08:36.837" LastActivityDate="2016-05-05T18:08:36.837" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27381" PostTypeId="2" ParentId="27373" CreationDate="2016-05-05T13:16:56.707" Score="14" Body="&lt;p&gt;If you are old enough to remember, the bias-ply automobile tires used in the 1960's would develop a flat spot when left sitting overnight. The flat spot would quickly go away when you started driving. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many of today's aircraft tires still use bias-ply tires and are also subject to flat spotting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Aj4wk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Aj4wk.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://books.google.ca/books?id=J6wnCQAAQBAJ&amp;amp;pg=PA176&amp;amp;lpg=PA176&amp;amp;dq=aircraft+bias+ply+tire+flat+spot+setting&amp;amp;source=bl&amp;amp;ots=wuHU_W5fOS&amp;amp;sig=exYER3t4838T0HhrusvfpBGc0cA&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwiOnva7qsPMAhUMFR4KHaRuCiYQ6AEIQDAH#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;noreferrer&quot;&gt;The Boeing 737 Technical Guide&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-05-05T16:37:27.460" LastActivityDate="2016-05-05T16:37:27.460" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27382" PostTypeId="1" AcceptedAnswerId="27383" CreationDate="2016-05-05T13:33:15.927" Score="10" ViewCount="6022" Body="&lt;p&gt;The takeoff minimums and (obstacle) departure procedures for the Asheville Regional Airport (KAVL) have special instructions due to the rising terrain in the vicinity of the airport. Instrument departures have special procedures to follow when departing IFR.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are special procedures for visual climb which mention VCOA. There is no mention of VCOA in the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/FAA-H-8083-15B.pdf&quot; rel=&quot;noreferrer&quot;&gt;Instrument Flying Handbook&lt;/a&gt;. Where is VCOA explained and what are the special considerations for pilots conducting this procedure?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.imgur.com/OlW45Ki.png&quot; alt=&quot;KAVL Departure Minimums&quot;&gt;&lt;/p&gt;&#xA;" OwnerUserId="8490" LastActivityDate="2016-05-05T14:20:48.677" Title="What is a Visual Climb Over Airport (VCOA) and how is it properly executed?" Tags="&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27383" PostTypeId="2" ParentId="27382" CreationDate="2016-05-05T14:20:48.677" Score="11" Body="&lt;p&gt;It's defined in the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/PCG.pdf&quot;&gt;pilot/controller glossary&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VISUAL CLIMB OVER AIRPORT (VCOA)− A departure option for an IFR&#xA;  aircraft, operating in visual meteorological conditions equal to or&#xA;  greater than the specified visibility and ceiling, to visually conduct&#xA;  climbing turns over the airport to the published “climb−to” altitude&#xA;  from which to proceed with the instrument portion of the departure.&#xA;  VCOA procedures are developed to avoid obstacles greater than 3&#xA;  statute miles from the departure end of the runway as an alternative&#xA;  to complying with climb gradients greater than 200 feet per nautical&#xA;  mile. These procedures are published in the ‘Take−Off Minimums and&#xA;  (Obstacle) Departure Procedures’ section of the Terminal Procedures&#xA;  Publications.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/AIM.pdf&quot;&gt;AIM&lt;/a&gt; 5-2-8 says that pilots must request it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Pilots are responsible to advise ATC as early as possible of the&#xA;  intent to fly the VCOA option prior to departure&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC orders&lt;/a&gt; 4-3-2 say that ATC may not offer it:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Do not solicit use of the Visual Climb over Airport (VCOA) option.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/FAA_Order_8260.3C.pdf&quot;&gt;TERPS&lt;/a&gt; 14-4 has all the technical details and explains the purpose, which is to allow aircraft that can't maintain a 200fpnm climb to climb safely within a limited area over the airport:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VCOA is an alternative method for pilots to depart the airport where&#xA;  aircraft performance does not meet the specified climb gradient.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The departure designer creates a vertical cylinder (called a &lt;em&gt;Visual Climb Area&lt;/em&gt; in the TERPS) of airspace over the airport that's safe to climb in, based on airport elevation, runway positions and a default airspeed of 250kt (although other airspeeds can be used). Even if the VCA dimensions aren't charted or stated in the DP, for an airport at 2000msl (KAVL is at 2162msl) the &lt;em&gt;radius&lt;/em&gt; of the cylinder is at least 2nm at 90kts, or 2.8nm at 250kts, which seems to be plenty for a spiral climb (in the aircraft I fly, anyway). And the climb has to be in visual conditions, so terrain clearance shouldn't be an issue.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know of any detailed guidance on how execute it, but &quot;climbing turns over the airport&quot; seems fairly clear. I've never done it myself, but I'd simply fly a continuous spiral climb after takeoff, up to the en route altitude mentioned in the procedures and go from there. &lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-05T14:20:48.677" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27386" PostTypeId="1" AcceptedAnswerId="27387" CreationDate="2016-05-05T16:52:56.867" Score="22" ViewCount="12215" Body="&lt;p&gt;Airliners are often (almost always actually) pushed back by a tug or a tractor to leave the gate. The tug can also tow an aircraft that cannot taxi by itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much force is required to pull or push a large airliner on the ground? In other words, what is the horsepower of these tugs?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: By large airliner, I mean Boeing 747 / 777 / A380 type, the ones which ATC append &quot;Heavy&quot; (or &quot;Super&quot;) to their call sign. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WOAGm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WOAGm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-05-05T17:10:19.323" LastActivityDate="2016-05-07T13:11:24.173" Title="How much force is needed to tow an airliner?" Tags="&lt;airport&gt;&lt;ground-operations&gt;" AnswerCount="4" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27387" PostTypeId="2" ParentId="27386" CreationDate="2016-05-05T17:13:31.460" Score="22" Body="&lt;p&gt;Tugs do not need that much horsepower, even the biggest tugs only have around 400bhp. What they do need is lots of torque for push/pull power, lots of weight to give it plenty of inertia, and big grippy tires to transfer the power to the surface. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The T80 in &lt;a href=&quot;http://www.littlebigtugcompany.co.uk/specs.htm&quot; rel=&quot;nofollow&quot;&gt;this link&lt;/a&gt; is pretty typical, 50-70 tons, 408bhp, and 1500 pound feet of torque. That's more than triple the torque of a hefty pickup. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2016-05-07T13:11:24.173" LastActivityDate="2016-05-07T13:11:24.173" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27391" PostTypeId="2" ParentId="27386" CreationDate="2016-05-05T19:02:55.900" Score="17" Body="&lt;p&gt;It only takes 7030 Kg, 309 BHP, and 553 lb/ft of torque. Well, it does if your tug is a &lt;a href=&quot;http://www.autocar.co.uk/car-news/motoring/touaregs-towing-ability-plane-silly&quot; rel=&quot;nofollow noreferrer&quot;&gt;VW Toureg&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://images.cdn.autocar.co.uk/sites/autocar.co.uk/files/styles/gallery_slide/public/volkswagen-touareg-231166102093.jpg?itok=SAMUMnFS&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://images.cdn.autocar.co.uk/sites/autocar.co.uk/files/styles/gallery_slide/public/volkswagen-touareg-231166102093.jpg?itok=SAMUMnFS&quot; alt=&quot;https://images.cdn.autocar.co.uk/sites/autocar.co.uk/files/styles/gallery_slide/public/volkswagen-touareg-231166102093.jpg?itok=SAMUMnFS&quot;&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Very pixeley image sourced from link above&lt;/sup&gt;&lt;br&gt;&#xA;This was a stunt done by the TV Show &lt;em&gt;Fifth Gear&lt;/em&gt; and &lt;em&gt;Autocar&lt;/em&gt; magazine. Realistically it doesn't take much, but I wouldn't count on the Toureg for day-to-day movements at JFK, ORD or ATL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;No, that's not a standard 747-200, &lt;a href=&quot;https://en.wikipedia.org/wiki/G-BDXJ&quot; rel=&quot;nofollow noreferrer&quot;&gt;it was modified&lt;/a&gt; for the James Bond movie &lt;em&gt;Casino Royale&lt;/em&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2017-03-10T09:42:48.627" LastActivityDate="2016-05-06T13:39:06.513" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27393" PostTypeId="1" AcceptedAnswerId="27394" CreationDate="2016-05-05T22:31:56.237" Score="10" ViewCount="598" Body="&lt;p&gt;Taking &lt;a href=&quot;http://airnav.com/airport/KEWR&quot;&gt;KEWR&lt;/a&gt; as an example, let us say that aircraft are taking off from 4L at N and landing on 4R.  Can I be cleared to cross 4L at say V, &lt;em&gt;behind&lt;/em&gt; the aircraft taking off on 4L, without interrupting the departure flow? Or will the runway need to be clear full-length to let me cross it?&lt;/p&gt;&#xA;" OwnerUserId="3825" LastEditorUserId="62" LastEditDate="2016-05-05T22:59:56.000" LastActivityDate="2016-05-24T20:14:06.877" Title="Can you be cleared to cross a runway *behind* an aircraft on takeoff?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;runways&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27394" PostTypeId="2" ParentId="27393" CreationDate="2016-05-05T22:50:35.770" Score="6" Body="&lt;p&gt;You can cross behind the aircraft on departure roll. This type of operation is done heavily at ATL, on the middle complex during an east flow. Aircraft will depart  runway 9L at M2, and arrivals from either of the south runway will cross behind them the whole time at M1, to get up to the gates.&lt;/p&gt;&#xA;" OwnerUserId="2785" LastActivityDate="2016-05-05T22:50:35.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27395" PostTypeId="2" ParentId="24803" CreationDate="2016-05-06T00:34:28.073" Score="2" Body="&lt;p&gt;Simply put, it's supposed to follow a constant flow/fanspeed curve but multiple stages and the mechanics of surging make it a lot more complex in practice.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The surge line slope on multistage compressors can range from a simple, single-parabolical [sic] relationship to a complex curve containing several break-points or even 'notches.'  The complexity of the surge line shape depends on whether or not the flow limiting stage changes with operating speed from one compression stage to another; in particular, very closely matched stage combinations frequently exhibit complex surge lines... The surge line in many cases has an approximately constant value of Q/N [mass flow/fan speed].  In many multi-stage units, and especially in units which are controlled by variable inlet guide vanes, the surge line curves bend dramatically at higher flows and speeds.&lt;br&gt;&lt;sup&gt;Source: &quot;Practical Aspects of Centrifugal Compressor Surge and Surge Control&quot; by  Meherwan P. Boyce &lt;a href=&quot;http://turbolab.tamu.edu/proc/turboproc/T12/T12147-173.pdf&quot; rel=&quot;nofollow&quot; title=&quot;Practical Aspects of Centrifugal Compressor Surge and Surge Control&quot;&gt;(pdf)&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So some of the shape comes from the curvature and irregular spacing of the constant speed lines, and some of the curve comes from adding in different stages.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, exact surge conditions are not easy to describe mathematically even if we know the properties of each stage in the compressor.  There are things like multi-blade interactions and boundary layer effect that make things difficult really fast.  These factors are so important because &lt;em&gt;surge is not quite the same as a stall on compressor blades&lt;/em&gt;.  Surge is a more complex unstable compressor flow resulting from stalls. Single blade stall, which isn't observed much in practice, will not cause a surge.  Surge happens when the stall propagates across several blades due to blocked incoming air.  There aren't easy,exact, and universal equations for this complex behavior unfortunately. &lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="5517" LastEditDate="2016-05-06T15:44:26.533" LastActivityDate="2016-05-06T15:44:26.533" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27397" PostTypeId="2" ParentId="27386" CreationDate="2016-05-06T06:41:45.083" Score="2" Body="&lt;p&gt;Actually, friction of the wheels, and the slope of the concrete is all you need.&#xA; &quot;Strongmen&quot; pulling buses only have to pull 300 pounds, once static friction is broken.&#xA;    &lt;a href=&quot;http://entertainment.howstuffworks.com/arts/circus-arts/question523.htm&quot; rel=&quot;nofollow&quot;&gt;See explanation HERE&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;416,299 pound planes (188.83 tons) like the CC-177 Globemaster III cargo plane can be pulled by It is MUCH BIGGER than a jumbo jet.&#xA;Youtube is full of videos of people pulling planes with teeth or &quot;other&quot; body parts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;110 BHP is the rating that the &quot;AIRCRAFT TOWING TRACTOR – MODEL BA10G40&quot; claims. It hauls 737's at up to 25 kmph.&#xA;&lt;a href=&quot;https://firangionindia.wordpress.com/military/indian-army/army-photos/aircraft-towing-tractor-model-ba10g40/&quot; rel=&quot;nofollow&quot;&gt;See full stats HERE&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14808" LastActivityDate="2016-05-06T06:41:45.083" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27398" PostTypeId="1" CreationDate="2016-05-06T08:21:15.720" Score="1" ViewCount="211" Body="&lt;p&gt;ICAO requires or recommends 25 degrees bank angle. On Boeing auto pilot it's possible to set 30 degrees to be used. What bank angles usually are used for Holding, ILS intercept en-route when flying manually and on autopilot? Any EASA rules in this field?&lt;/p&gt;&#xA;" OwnerUserId="8466" LastActivityDate="2016-05-06T08:21:15.720" Title="What bank angles are used for IFR operations?" Tags="&lt;instrument-flight-rules&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-05-06T16:24:26.873" ContentLicense="CC BY-SA 3.0" />
  <row Id="27399" PostTypeId="2" ParentId="9440" CreationDate="2016-05-06T13:13:08.957" Score="1" Body="&lt;p&gt;From publicly available FAA tie-up data I figured out what the algorithms are that relate the American N numbers to their ICAO hex address - there are 24 algorithms in all for the 12 categories of 915399 possible N numbers. I turned these into a little Windows commandline application which works two-ways, N number &amp;lt;--&gt; ICAO address. If somebody is interested, just ask for it : hero@ccstrombeek.be. The derived algorithms are available too (in Dutch only).&lt;/p&gt;&#xA;" OwnerUserId="14810" LastEditorUserId="14810" LastEditDate="2017-03-06T12:31:43.087" LastActivityDate="2017-03-06T12:31:43.087" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27400" PostTypeId="2" ParentId="14734" CreationDate="2016-05-06T15:18:02.663" Score="4" Body="&lt;p&gt;I know very little about this, but it looks like you can fly commercially with an SPL if you pass an additional checkride. This is from the &lt;a href=&quot;https://www.caa.co.uk/General-aviation/Pilot-licences/EASA-requirements/PPL-SPL-BPL/SPL-requirements/&quot; rel=&quot;nofollow&quot;&gt;UK CAA&lt;/a&gt;, and the same wording is quoted on a bunch of European gliding organization sites:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;You cannot operate commercially, or receive any kind of payment, until&#xA;  you:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Are 18 years of age or over &lt;/li&gt;&#xA;  &lt;li&gt;Have completed 75 hours of flight time or 200 launches, after your licence has been issued &lt;/li&gt;&#xA;  &lt;li&gt;Have passed a proficiency check with an examiner&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.easa.europa.eu/system/files/dfu/AMC%20and%20GM%20to%20Part-FCL.pdf&quot; rel=&quot;nofollow&quot;&gt;EASA's Part-FCL guidance&lt;/a&gt; defines what the additional checkride includes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;AMC1 FCL.205.S(b) SPL — Privileges and conditions&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;CONTENTS OF THE PROFICIENCY CHECK FOR THE EXTENSION OF SPL PRIVILEGES TO EXERCISE COMMERCIAL PRIVILEGES ON A SAILPLANE&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that it calls it an &quot;extension&quot; of SPL privileges, which strongly implies that an SPL by itself doesn't allow commercial privileges. There is one exception, which is that an instructor can be paid to instruct with just an SPL. The CAA site says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The exception to this is for holders of a SPL with instructor or&#xA;  examiner privileges, who can be paid for the following:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;Flight instruction&lt;/li&gt;&#xA;  &lt;li&gt;Conducting skill tests and proficiency checks&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;for the LAPL (S) or SPL and any associated ratings and endorsements.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-06T15:18:02.663" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27401" PostTypeId="1" AcceptedAnswerId="27415" CreationDate="2016-05-06T15:18:14.463" Score="110" ViewCount="23282" Body="&lt;p&gt;Is there any theoretical or practical limit to the maximum number of passengers - and therefore size - one can build an airplane for?&lt;/p&gt;&#xA;" OwnerUserId="14811" LastEditorUserId="62" LastEditDate="2016-05-06T17:43:40.237" LastActivityDate="2021-05-24T12:48:43.993" Title="Is there a maximum possible size for an airplane?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;commercial-aviation&gt;" AnswerCount="9" CommentCount="19" FavoriteCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="27402" PostTypeId="2" ParentId="27401" CreationDate="2016-05-06T15:50:24.183" Score="24" Body="&lt;p&gt;Theoretically, unlimited (well bigger than is practically necessary)...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TL;DR&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airplanes scale fairly well and it would be &lt;em&gt;physically&lt;/em&gt; possible to build and airplane of just about any size. Granted there are some things that come into play from a structure standpoint but there are surely ways around that. You may have to stray away from the traditional single fuselage, two wing and empennage design but none the less. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are lots of realistic factors that will stand in your way before you even need to design such a plane. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You don't have enough money to build such a plane &lt;/li&gt;&#xA;&lt;li&gt;Boeing does not have enough money to build such a plane &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Juan_Trippe&quot; rel=&quot;nofollow noreferrer&quot;&gt;Juan Trippe&lt;/a&gt; has no interest in such a plane so there is probably no reason to build it. &lt;/li&gt;&#xA;&lt;li&gt;There are no runways that could handle such an aircraft. Planes like the A380 and 747 are already route limited by runway length/weight capacity. You would need to modify runways to handle anything significantly bigger. That is of course assuming that it lands in a similar fashion to most airliners (i.e. not VTOL)&lt;/li&gt;&#xA;&lt;li&gt;What route is it going to fly? Planes are not the size they are because we cant build them bigger, they are the size they are because the routes dictate them being such a size. Do you really need to move 1,000 people on a given route at once? How many routes have this much travel density? &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Let's look at this hypothetically, &lt;a href=&quot;https://aviation.stackexchange.com/questions/27401/is-there-a-maximum-possible-size-for-an-airplane#comment67513_27401&quot;&gt;Jamiec makes an excellent point&lt;/a&gt; that a plane that has the capacity in excess of 7Bn would be kind of useless so let's take that as a maximum. XKCD what if &lt;a href=&quot;https://what-if.xkcd.com/8/&quot; rel=&quot;nofollow noreferrer&quot;&gt;covers this in a similar question&lt;/a&gt; and estimates that shoulder to shoulder all the people on earth take up roughly the size of Rhode Island. For the sake of argument lets say that you would need seats and toilets and what not for this many people so to fit everyone on earth in a plane you would need maybe twice the size of Rhode island or a bit more. Unlike that question we can build up so a 4-8 story (or any amount) of plane would be plausible. The average &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-27E.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA person weighs about 180 lb (81.65 kg)&lt;/a&gt; so you would need to lift   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;1,260,000,000,000 lb Or 630,000,000 tons (572,000,000,000 kg or 572,000,000 metric ton )&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To provide a frame of reference the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airbus_A380&quot; rel=&quot;nofollow noreferrer&quot;&gt;A380 has a maximum structural payload of 330,300 lb (149,822 kg)&lt;/a&gt;. Keep in mind this is only payload, you also need to lift the weight of the airframe, engines, and fuel (if you actually want to go anywhere). So basically you would need a multi level plane close to the size of Rhode Island that had most of the combined thrust available on the planet and enough liquor to keep everyone calm for the flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The structural issue in some regards boils down to wing loading. One commonly self imposed limit these days is that most planes are typical &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_configuration&quot; rel=&quot;nofollow noreferrer&quot;&gt;low wing cantilever monoplanes&lt;/a&gt; so we view things in relation to that. In other words the fuselage may stress about the wing mounting points and the wings are generally long and low but there is nothing preventing us from using an alternate design with multiple wings or a full lifting body design to accomplish the structure we need. As such the idea of big wings can be overcome and historically this is how the problem was solved in early aviation (tri-planes, etc...) The weight issue (from a practical standpoint) is something we concern ourselves with for efficiency reasons. If we are just building a giant plane we can use jets, rockets and all manners of high thrust devices for the purpose of science. You could fly a cement plane if it was shaped right and you had enough thrust. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Remember if Thrust &gt; Drag and Lift &gt; Weight you will fly (I learned this the first day in flight school). Doing so in a controlled and organized manner took significantly more time to learn....  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;-- Edit -- &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the question has been edited to involve the passenger count there are other issue that crop up. &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;You need to realistically load and unload the plane which takes time. A plane that takes too long to load and unload will not be economical to operate.  &lt;/li&gt;&#xA;&lt;li&gt;Weight (&lt;a href=&quot;http://articles.orlandosentinel.com/2005-08-11/news/VBIGAIR11_1_airline-passengers-fuel-center-of-gravity&quot; rel=&quot;nofollow noreferrer&quot;&gt;Americans are getting fat&lt;/a&gt;) (see above) &lt;/li&gt;&#xA;&lt;li&gt;You need a reason to move that many people that far all at once.&lt;/li&gt;&#xA;&lt;li&gt;Depending on flight length you need to consider food, water, and restrooms to accommodate everyone (waste tanks are not infinitely large). &lt;/li&gt;&#xA;&lt;li&gt;Are there even enough people in one place? Planes move people (and often stuff) from one place to another but let's take NYC for example which has a population of about &lt;a href=&quot;http://www1.nyc.gov/site/planning/data-maps/nyc-population/current-future-populations.page&quot; rel=&quot;nofollow noreferrer&quot;&gt;8.5 million people&lt;/a&gt; the chances that all of them are going to the same place at once is near 0%. So you don't need an 8.5 million passenger plane, but you can start a bit smaller. &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;From an airline standpoint (The people actually buying) planes like the 747 are already big enough and expensive enough. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_747&quot; rel=&quot;nofollow noreferrer&quot;&gt;747 nearly bankrupt Boeing&lt;/a&gt; at the time but has had a fairly successful run since. The A380 is fairly new but it will be interesting to see how it changes the game. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="9401" LastEditDate="2020-03-27T16:48:55.783" LastActivityDate="2020-03-27T16:48:55.783" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="27403" PostTypeId="2" ParentId="27369" CreationDate="2016-05-06T17:00:02.850" Score="6" Body="&lt;p&gt;Raymer's G is a little unusual. In effect, it is the tangent of the flight path angle $\gamma$, and since his equations are for small values of $\gamma$, we can assume that it is approximately equal to $sin\gamma$ or $\gamma$ itself when expressed in radians.&#xA;$$G \approx \gamma$$&#xA;Next, the expression $\pi\cdot AR\cdot e$: This is part of the square root of the lift coefficient for minimum drag. The complete equation is:&#xA;$$c_{L\:(minimum\:drag)} = \sqrt{c_{D0}\cdot\pi\cdot AR\cdot e} = c_{L\:(md)}$$&#xA;Next, I need to express that thrust-to-weight ratio differently. As long as we keep $\gamma$ small:&#xA;$$\gamma = \frac{T}{W} - \frac{c_D}{c_L} =&amp;gt; \frac{T}{W}-\gamma = \frac{c_D}{c_L}$$&#xA;Now I can rewrite the equation of your first question:&#xA;$$\frac{W}{S} = q\cdot\frac{\frac{c_D}{c_L}\cdot \frac{c^2_{L\:(md)}}{c_{D0}}}{2} ± q\cdot\frac{\sqrt {\left(\frac{c_D}{c_L}\right)^2\cdot\left(\frac{c^2_{L\:(md)}}{c_{D0}}\right)^2 - 4\cdot c^2_{L\:(md)}}}{2}$$&#xA;and when I restrict the equation to the minimum drag point where $c_{D0} = c_{Di}$, I can write&#xA;$$\frac{W}{S} = q\cdot c_{L\:(md)} ± q\cdot\sqrt {c^2_{L\:(md)} - c^2_{L\:(md)}}$$&#xA;Fancy that! The expression under the root becomes zero when I look at the polar point of minimum drag! The only variable term under the square root is the ratio $\frac{c_D}{c_L}$, and it reaches its minimum at the $c_{L\:(md)}$ point. When I move away from this polar point, I should get two valid solutions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I guess these two wing loadings allow to fly with the specified flight path angle at the given polar point and thrust-to-weight ratio. Since the weight is prescribed by the thrust-to-weight ratio, the solution is actually for two different wing areas. The smaller wing requires a higher speed and the larger wing a smaller speed than what you get at the lowest drag point. Between both, the speed and wing area should result in configurations which achieve a higher flight path angle $\gamma$, and outside of this interval no level flight should be achievable with the resulting wing areas and speeds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot follow how you arrive at the second question. The term under the square root should be&#xA;$$\left(\frac{T}{W}\right)^2 - 2\cdot\frac{T}{W}\cdot G + G^2 ≥ \frac{4\cdot c_{D0}}{\pi\cdot AR\cdot e}$$&#xA;But when I insert again as explained above, I can write for the term under the root:&#xA;$$\left(\frac{c_D}{c_L}\right)^2 - \frac{4\cdot c^2_{D0}}{c^2_{L\:(md)}}$$&#xA;so the condition for a positive root is&#xA;$$\frac{c_{D0}+c_{Di}}{c_L} ≥ \frac{2\cdot c_{D0}}{c_{L\:(md)}}$$&#xA;or&#xA;$$ \frac{c_{D0}}{c_L} + \frac{c_L}{\pi\cdot AR\cdot e} ≥ 2\cdot\sqrt{ \frac{c_{D0}}{\pi\cdot AR\cdot e}}$$&#xA;which is certainly true; both sides of the equation are equal at the lowest drag polar point and away from it the left side is bigger and the right side stays constant.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you just isolate the term under the root and look at it by itself, I doubt you have something that corresponds to a realistic configuration. You need to extract both numerator and denominator to keep the physical analogies intact. What Raymer does is to look at the term under the root in isolation and then postulates that the first summand must be larger than the second. He puts both on the two sides of an inequality and extracts the roots on both sides separately. Then he moves G over to the other side. There is no second version of the inequality possible.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-16T05:18:47.497" LastActivityDate="2016-05-16T05:18:47.497" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27406" PostTypeId="1" CreationDate="2016-05-06T21:39:06.023" Score="10" ViewCount="946" Body="&lt;p&gt;For large drones like the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Atomics_MQ-9_Reaper&quot;&gt;Reaper&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Northrop_Grumman_X-47A_Pegasus&quot;&gt;X-47&lt;/a&gt;, and aircraft like that, how do the &quot;pilots&quot; communicate with ATC when they need to?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="12220" LastEditDate="2016-05-06T22:37:47.923" LastActivityDate="2016-05-07T14:12:30.107" Title="How do large drones communicate with ATC?" Tags="&lt;radio-communications&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27407" PostTypeId="2" ParentId="27401" CreationDate="2016-05-06T21:39:31.383" Score="51" Body="&lt;p&gt;It is no accident that the biggest birds are flightless. The ability to fly goes down with increasing size, so there is also an upper limit for aircraft. The main reason is that as size increases, masses go up with the cube of the size increase while the load-carrying structures like wing spar cross sections only grow with the square of the size increase. This power law is the simplest of the &lt;a href=&quot;http://www.av8n.com/physics/scaling.htm&quot; rel=&quot;noreferrer&quot;&gt;scaling laws&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the loads on an aircraft's wing depend not only on its size, but also on many more parameters (angle of attack, speed, aspect ratio …), there is no clear boundary, and advances in materials help to shift the size limit up. If one would try to build the biggest airplane in the world, the wingspan could easily be double of what todays biggest airplanes measure, but the utility of this airplane would be very limited.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using this airplane for passenger travel would add more restrictions like the number of emergency exits and the maximum distance to the nearest exit, but this could be overcome by using several smaller fuselages. A double-hull airplane would also spread out the payload weight, so the wing would experience a reduced root bending moment. Going from this (&lt;a href=&quot;http://modelismo.wehrmacht-info.com/wp-content/uploads/2013/07/Bundesarchiv_Bild_101I-385-0587-07_Flugzeug_Heinkel_He_111_H-Z.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/T6fCp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/T6fCp.jpg&quot; alt=&quot;He-111H in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;to this (&lt;a href=&quot;http://www.airwar.ru/image/idop/cww2/he111z/he111z-3.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8vuPY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8vuPY.jpg&quot; alt=&quot;He-111Z in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;would immediately raise the size limit substantially. However, it would require new, wider runways to take off from. And adding more fuselages to the same wing will run into flutter problems soon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next indication could be &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_large_aircraft#Projects&quot; rel=&quot;noreferrer&quot;&gt;designs which have been studied&lt;/a&gt; and deemed feasible but were eventually not built for economical reasons. Here the biggest are ground effect vehicles: Flying slowly in dense air pushes the size limit up. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_Pelican&quot; rel=&quot;noreferrer&quot;&gt;Boeing Pelican&lt;/a&gt; was planned with 152 m wingspan, and &lt;a href=&quot;http://www.beriev.com/eng/Be-2500_e/Be-2500_e.html&quot; rel=&quot;noreferrer&quot;&gt;Beriev proposed one&lt;/a&gt; with 2500 t take-off mass and 125.5 m wing span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would guess that a wingspan of 200 m is still feasible, and when &lt;a href=&quot;http://www.uh.edu/engines/heliosinflight.jpg&quot; rel=&quot;noreferrer&quot;&gt;spreading the weight&lt;/a&gt; even 500 m should be realistic, but totally unpractical. Taking a lesson from history, this would be a multi-hulled flying boat which flies in ground effect, similar to the (mono-hulled) &lt;a href=&quot;https://aviation.stackexchange.com/questions/23675/which-came-to-be-first-bigger-airplanes-or-longer-runways/23687#23687&quot;&gt;biggest aircraft record holders&lt;/a&gt; in the 1920s.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2018-01-07T22:43:30.920" LastActivityDate="2018-01-07T22:43:30.920" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27408" PostTypeId="2" ParentId="27401" CreationDate="2016-05-06T22:31:54.830" Score="8" Body="&lt;p&gt;Certainly a plane can't be bigger than Earth. I would even say 10 miles long aircraft is quite useless, because you need to have some transportation inside of it to deliver all passengers on theirs seats.  An airport for keeping such places should be also a big. Therefore limitations are coming not from weight/lifting power, they are coming from practical uses of such big planes.&lt;/p&gt;&#xA;" OwnerUserId="14816" LastActivityDate="2016-05-06T22:31:54.830" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27410" PostTypeId="2" ParentId="27386" CreationDate="2016-05-07T00:37:43.473" Score="9" Body="&lt;p&gt;Actually Boeing (publicly) publishes this data for all of its aircraft in the &lt;a href=&quot;http://www.boeing.com/commercial/airports/plan_manuals.page&quot; rel=&quot;noreferrer&quot;&gt;Airplane Characteristics for Airport Planning Manuals&lt;/a&gt;. Here is the chart for the 747-8:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/d5ft4.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/d5ft4.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;Total Traction Wheel Load&quot; is the required weight of the tug on its drive wheels, while the &quot;Drawbar Pull&quot; is the force on the actual towbar/NLG.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-05-07T00:37:43.473" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27411" PostTypeId="2" ParentId="25940" CreationDate="2016-05-07T04:38:35.580" Score="4" Body="&lt;p&gt;Disclaimer: I have no copy of Raymer's book, so I have to guess what this table looks like.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There should be no direct dependency, except that all aircraft need to operate in the real world. If you look at the wing loading of regular jet transports, you will notice that they bunch together around 500 - 600 kg/m². This is the maximum wing loading which still allows them to operate from normal airports - go to higher values an you need a &lt;a href=&quot;https://en.wikipedia.org/wiki/Rogers_Dry_Lake&quot; rel=&quot;nofollow&quot;&gt;dry lakebed&lt;/a&gt; for take-offs and especially landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To push the resulting wing to higher flight speeds needs more thrust - hence the dependency. If you start with a higher wing loading (say, 800 kg/m²), the thrust/weight ratio for reaching the same Mach number is lower. The approach and landing speeds grow with wing loading as well, which in turn affects the resulting landing distance. I guess there is a maximum landing distance requirement for all aircraft in the table which is not explicitly mentioned.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-05-07T04:38:35.580" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27414" PostTypeId="1" CreationDate="2016-05-07T12:25:03.470" Score="8" ViewCount="284" Body="&lt;p&gt;I am interested to know if there are any changes in propeller performance (thrust, efficiency) with respect to distance from obstructions such as the fuselage or wings? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am particularly looking for studies or experiments. Mostly interested in tractor/puller configurations but info for pushers would be nice to know too.&lt;/p&gt;&#xA;" OwnerUserId="14824" LastEditorUserId="14824" LastEditDate="2016-05-07T14:57:57.913" LastActivityDate="2018-12-24T23:42:09.047" Title="How does the performance of an aircrafts propeller change with respect to distance from obstructions?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;propeller&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27415" PostTypeId="2" ParentId="27401" CreationDate="2016-05-07T13:09:38.980" Score="34" Body="&lt;p&gt;Yes, there is an upper limit, but that upper limit might change with technological innovation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airplane flies because of the lift coefficient $L=\frac12\rho v^2 A C_L$, with $v$ the airspeed, which is a combination of the speed of the plane and the wind speed, $\rho \approx 1 \, \text{kg m}^{-3}$ at a theoretical mimimum of 5 km height (remember that most planes reach 10 km, but I took this a little more extreme to show an upper limit), $A$ the area, and $C_L$ an coefficent with a typical value less than 2, that might change with technological innovation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the only factors we can influence are $v$ and $A$. However, if we increase $A$, the mass $m$ increases faster than the area $A$ because there is more material needed to avoid the plane form breaking under the huge forces. Increasing $A$ quadratically gives more than a quadratically in $m$, and hence in the needed $L$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we increase $v$, we need more fuel. The amount of fuel per distance unit increases linearily in $v$, because it increases quadratically per unit of time in $v$. Hence $L$ increases quadratically where $m$ only increases linearily. This means that we might do something with increasing $v$. That means that airplanes have to go faster before liftoff, which will need drastically longer takeoff lanes.&#xA;Note that we can't keep increasing $v$ because we can't lose control. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In summary, things we can improve are $v$, the speed, $C_L$, with technological innovations and $\rho$ by lowering flying height. However, it is not practical.&lt;/p&gt;&#xA;" OwnerUserId="14823" LastEditorUserId="14823" LastEditDate="2016-05-08T14:46:28.730" LastActivityDate="2016-05-08T14:46:28.730" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27416" PostTypeId="1" CreationDate="2016-05-07T13:18:50.070" Score="12" ViewCount="30501" Body="&lt;p&gt;As far as static thrust, does a shrouded/ducted propeller outperform an un-shrouded propeller? It seems that the guide blades on the bottom of the duct would allow little more thrust to be extracted from the vortex the prop generates by redirecting the air flow. Also the duct seems like it could &quot;focus&quot; the propelled air (like a rocket thruster) resulting in better thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HcB1Xm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HcB1Xm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;&lt;sup&gt;(&lt;a href=&quot;http://diydrones.com/profiles/blogs/3d-printed-propeller-shroud-kit&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course I can see how an improperly implemented duct could really kill efficiency (creating more interference and turbulence), but what about a well designed one? And if they are better, why wouldn't we seem most propeller aircraft use them (what is the advantage about not having the duct)?&lt;/p&gt;&#xA;" OwnerUserId="14825" LastEditorUserId="14897" LastEditDate="2017-02-16T06:11:58.287" LastActivityDate="2020-10-25T06:15:59.890" Title="Are ducted fans more efficient?" Tags="&lt;propeller&gt;&lt;efficiency&gt;&lt;propulsion&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27417" PostTypeId="2" ParentId="27406" CreationDate="2016-05-07T14:12:30.107" Score="7" Body="&lt;p&gt;They have an onboard VHF radio that can be used to receive and transmit on local frequencies.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, on the MQ-1B Predator you will see a small fin on the back of the aircraft behind the GPS dome. That is an omni-directional antenna which can transmit VHF. The Global Hawk has a similar capability.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-07T14:12:30.107" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27419" PostTypeId="1" AcceptedAnswerId="27423" CreationDate="2016-05-07T16:33:56.780" Score="9" ViewCount="9453" Body="&lt;p&gt;As per this image of the A350, the crew rest areas have been placed on the top of the fuselage. How can this be possible and how would the crew get into the rear one since it seems that it is placed above first class?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that the front one is accessible from the cockpit, but the second one seems to be straight on top the first/business class section. Is this actually practical?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BFFAb.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BFFAb.png&quot; alt=&quot;A350 diagram showing location of crew rest areas&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2016-05-07T23:36:37.993" LastActivityDate="2017-03-27T14:37:16.203" Title="How is the crew rest area on the A350 accessed?" Tags="&lt;crew&gt;&lt;airbus-a350&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27420" PostTypeId="2" ParentId="27401" CreationDate="2016-05-07T16:37:51.800" Score="5" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Floating_city_%28science_fiction%29&quot; rel=&quot;noreferrer&quot;&gt;flying city&lt;/a&gt;, such as those proposed by &lt;a href=&quot;http://www.editorialtenov.com/en/books/georgii-krutikov-the-flying-city-and-beyond-s-o-khan-magomedov/&quot; rel=&quot;noreferrer&quot;&gt;Georgii Krutikov&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As most of the problems seem related to taking off and landing, best probably would be to keep such a giant plane constantly airborne, very high where the air is more stable and compose of multiple modules that could take off self-dependently and then join that bigger &quot;flying castle&quot; - like a space station. Docking seems tricky but should be possible as areal refueling is possible. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This castle could be solar-powered or nuclear-powered, for instance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is more difficult to think what would be the use of it.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="3117" LastEditDate="2016-05-08T16:07:25.597" LastActivityDate="2016-05-08T16:07:25.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27422" PostTypeId="1" AcceptedAnswerId="27431" CreationDate="2016-05-07T16:53:17.100" Score="12" ViewCount="2559" Body="&lt;p&gt;I'm studying the fundamentals of jet propulsion and its applications. I really have this next question and haven't found an answer yet: why do jets use a shaft (or more) to connect the turbine(s) to the compressor device(s), but not a &quot;rotating drum&quot; instead?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I call a &quot;rotating drum&quot; (I sketched it below) is a thin, rotating cylinder that has built-in rotor blades at the beginning and exit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to know if this is a feasible arrangement, and what would be the disadvantages of it. I think this might be unfeasible because:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;There would be a lot of thermal stress at the middle of the drum.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;But if we were to overcome this drawback somehow, I think we would benefit in the following ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Less weight, I think, with respect the traditional shaft system.&lt;/li&gt;&#xA;&lt;li&gt;More internal space (no hollow) for other demanding components, like the combustor. The combustor could be made a bit larger, thus increasing the burning efficiency (more reaction time for reactants, ...).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HIKPS.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HIKPS.jpg&quot; alt=&quot;Rotating-Drum&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know how correct/wrong I am. This is a question out of pure curiosity and I wanted to get some feedback on it. Should I go ahead and start working on a small scale prototype of it? Hope my question here is not too basic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS: The sketch I made is just that: a sketch. Therefore, important things like the relative number of stages compressor-turbine, or the increasing/decreasing areas for each of those two components, do not appear.&lt;/p&gt;&#xA;" OwnerUserId="7990" LastActivityDate="2018-12-09T10:27:56.717" Title="Compressor-Turbine: Why a shaft and not kind of a &quot;rotating drum&quot;?" Tags="&lt;jet-engine&gt;&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="3" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27423" PostTypeId="2" ParentId="27419" CreationDate="2016-05-07T17:36:52.200" Score="14" Body="&lt;p&gt;It looks like your image came from &lt;a href=&quot;http://bloga350.blogspot.com/2012/10/where-pilots-and-flight-attendants.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;this article&lt;/a&gt;, since they have the exact same one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to Boeing, this is the &lt;strong&gt;most&lt;/strong&gt; practical place, and Airbus has finally decided they agree.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;For the first time in Airbus aircraft –and after benchmarked[sic] Boeing´s configuration-, the A350 XWB’s crew rest compartments are in the aircraft crown.&lt;br&gt;&lt;sup&gt;--All images and quotes from article linked above unless otherwise noted.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This image shows that the cabin crew's rest area is at the rear of the aircraft, while the flight crew's is up front. It also shows how they've shifted out of the basement and into the attic:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pMgQN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pMgQN.jpg&quot; alt=&quot;A350XWB Crew Rest Compartments&quot;&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Image courteously, but unknowingly supplied by &lt;a href=&quot;http://www.core77.com/posts/27476/The-Part-of-the-Plane-You-Never-Get-to-See-What-Do-Cabin-Crews-Chillaxation-Spots-Look-Like&quot; rel=&quot;nofollow noreferrer&quot;&gt;core77.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further down in that article they state &lt;strong&gt;why&lt;/strong&gt; the crew rest areas are where they are:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The A350 XWB crew rests, located overhead in the crown area, have no impact on revenues space – whether cargo or passenger – and contribute to the efficiency of the A350 XWB cabin.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also explains &lt;strong&gt;how&lt;/strong&gt; you get there:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Entrances to these rest areas are located outside the passenger cabin, so they do not use up seat space. “This is the first time a crew rest area on an aircraft will have no revenue-generating impact,” A350 XWB Marketing Director Bausor said.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Unfortunately, I'm guessing that the crew rest areas do &lt;em&gt;not&lt;/em&gt; actually have a skylight one might infer from this image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://1.bp.blogspot.com/-zNGGryN1Z74/UIw3VmcvzAI/AAAAAAAAAZs/TSbdBkytuR8/s320/cabinrest1.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://1.bp.blogspot.com/-zNGGryN1Z74/UIw3VmcvzAI/AAAAAAAAAZs/TSbdBkytuR8/s320/cabinrest1.jpg&quot; alt=&quot;https://1.bp.blogspot.com/-zNGGryN1Z74/UIw3VmcvzAI/AAAAAAAAAZs/TSbdBkytuR8/s320/cabinrest1.jpg&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm sure the day-shift crew would enjoy sleeping under the stars at night, though the night-shift crew probably wouldn't enjoy the bright sunlight while trying to sleep.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2017-03-27T14:37:16.203" LastActivityDate="2017-03-27T14:37:16.203" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27424" PostTypeId="2" ParentId="27422" CreationDate="2016-05-07T20:43:32.027" Score="13" Body="&lt;p&gt;A rotating drum will have a higher inertia. When the pilot commands a thrust increase, spooling up the drum will take longer than spooling up a shaft. Also, a big drum is harder to balance well than a thin shaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, what you propose is not so far from general practice: The high pressure spool on modern engines is quite big already, but it is still on the inside of the blades. See the cut-away picture of the &lt;a href=&quot;https://en.wikipedia.org/wiki/General_Electric_Passport&quot; rel=&quot;nofollow noreferrer&quot;&gt;General Electric Passport&lt;/a&gt; engine for example (&lt;a href=&quot;http://www.air-cosmos.com/upload/18/pics/2014/02/web/530d1afb8e523.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0sEOG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0sEOG.jpg&quot; alt=&quot;General Electric Passport engine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here it is interesting to see that the core components are quite a bit smaller than the channel for the bypass air, but the high pressure spool uses all the space left by the combustor. You can also see that the low pressure spool must be thin to allow enough cross section for the first stages of the high pressure compressor. Using a drum here would not only increase the inertia of the low pressure spool, but also of the whole high pressure compressor. Putting the drum on the outside of the blades would put it in the way of bleed air lines, accessories driveshafts and fuel lines. Also, making the stator vanes moveable would be much harder. The cut-away should make it obvious that the diameter of the high pressure section was kept as small as practical. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2017-04-22T16:11:10.680" LastActivityDate="2017-04-22T16:11:10.680" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27425" PostTypeId="2" ParentId="27318" CreationDate="2016-05-07T22:18:04.767" Score="4" Body="&lt;p&gt;Ok - got word from the local a&amp;amp;p that this stem is a part of the aux fuel pump. It drains the motor side of the pump of any fuel in case the seal that separates the motor from the pump fails. You wouldn't want fuel getting inside of where the motor has current and sparks, hence this &quot;stem&quot; is the safety backup. The entire pump had to be replaced because overhauling made less sense due to the age of the pump. Turns out it wasn't in the diagrams at all!&lt;/p&gt;&#xA;" OwnerUserId="11216" LastActivityDate="2016-05-07T22:18:04.767" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27426" PostTypeId="2" ParentId="24617" CreationDate="2016-05-07T22:48:54.737" Score="1" Body="&lt;p&gt;a lot of the small regional airports where I live in france have the firefighters doing a multi task job. they handle baggage,fuel aircraft drive the vehicle with the steps to the aircraft and other jobs. &lt;/p&gt;&#xA;" OwnerUserId="14762" LastActivityDate="2016-05-07T22:48:54.737" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27428" PostTypeId="1" AcceptedAnswerId="27429" CreationDate="2016-05-08T00:04:06.087" Score="7" ViewCount="548" Body="&lt;p&gt;On a recent flight from Washington, DC to Toronto, the pilot gave very specific directions to rebalance the plane (a Dash-8 IIRC), something like &quot;someone needs to move to seat 11E.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How did he know that putting someone in seat 11E would balance the plane properly? Does the plane weigh itself or is there a computer model somewhere that tells him what to do? Or would an experienced pilot be able to look at the seat chart and know what to do? &lt;/p&gt;&#xA;" OwnerUserId="14835" LastEditorUserId="62" LastEditDate="2016-05-08T14:46:42.763" LastActivityDate="2016-05-09T09:06:19.540" Title="How do pilots of small planes know where to move people?" Tags="&lt;airline-operations&gt;&lt;passenger&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27429" PostTypeId="2" ParentId="27428" CreationDate="2016-05-08T02:08:31.170" Score="6" Body="&lt;p&gt;Depending on the airline, and the size of the aircraft, the Weight and Balance calculations for each flight are either done by the pilots, or by the Flight Operations, Load Department. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If it is done by the pilots, they will receive the loading information which contains the weight and location of all passengers, cargo, and fuel. They then calculate manually, or by using software, the exact center of gravity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If done by the Load Department, the center of gravity information will be communicated by radio or ACARS datalink. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is not unusual to require a last minute seating or cargo change in order to ensure the aircraft is within the proper center of gravity limits for takeoff. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="100" LastEditDate="2016-05-09T09:06:19.540" LastActivityDate="2016-05-09T09:06:19.540" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27430" PostTypeId="2" ParentId="27416" CreationDate="2016-05-08T04:00:35.350" Score="16" Body="&lt;p&gt;there is a lot going on here.  Short answer is that a ducted fan (what you have pictured) can produce a lot more thrust (experiments from one paper say twice as much) than an open rotor of the same size.  The big thing that these ducted fans have going for them is the fact that tip losses become negligible because there simply isn't room for the tip vortex to develop because there is a duct in the way!  Simple, easy solution that works well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, nothing comes for free.  One, you have to have the duct there, which is weight &amp;amp; money (you have to build the duct and the support structure, which adds some drag too).  Think of scale too--as propellers get larger, the duct has to grow with them.  Imagine the difficulties in putting a 20' duct on a B-36 propeller!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Second, the manufacturing tolerances on the duct are critical--the tighter it is, the more efficient you are (to a limit, naturally)...but the tighter it is, the more susceptible you are to having your blades strike the duct due to flexing of the duct or the blades.  And, speaking of flexing blades and the necessary support structure you'd need, this could make pitch control (on a propeller, variable pitch, and on a rotor, cyclic and collective) difficult to implement, depending on which of those schemes you're looking to do.  Then again, for a small implementation using RPM control...maybe you don't need those anyhow.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, while a crosswind on an open rotor leads to a sudden decrease in power, a crosswind on a ducted fan leads to a sudden pitching moment due to the lip of the duct and the asymmetric inflow to the fan (which, since you're now producing more thrust to begin with, asymmetric inflow effects become even more pronounced).  Now, if you stick this on the front of a typical Cessna 172, say, and throw a crosswind at it (which, if you think of takeoffs and landings, which since they must be in a certain direction, having a crosswind is actually quite likely) imagine the yawing moments that would be induced by the propeller (proportional to the static thrust) -- even before the aircraft got off the ground and before you have a lot of control authority to counteract it!  A similar scenario in the air could be as dramatic.  And, yeah, you could throw some guide vanes at it to help, but nothing comes for free.  Guide vanes, which is a workable solution, now mean that you need to have actuator(s) for those vanes, power &amp;amp; maybe hydraulics for the actuator(s), mounts for the actuators, hinges for the vanes, linkages from the actuator(s) to the vanes, redundancy for the actuation or some means of facilitating control in an emergency...it's a lot of work.  Or, by contrast, you could just bolt a fixed pitch prop on a shaft at the front of said Cessna 172 and call it a day.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the long run, and this is some speculation, I think it just leads to a more complex system, particularly in full-size implementations, which is a maintenance, cost, and manufacturing headache that isn't worth having if you can get plenty of performance from a regular open propeller.  If you venture into the world of diffuser augmented wind turbines, there have been similar debates going on for decades...and a ducted wind turbine has yet to be successful on the large scale.  Similarly, while ducted fan aircraft have flown...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tVR1x.jpg&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tVR1x.jpg&quot; alt=&quot;Ryan XV-5A Vertifan, circa 1950&quot;&gt;&lt;/a&gt;&#xA;(Ryan XV-5A Vertifan, circa 1950.  The ducted fans are underneath the circular domes on the wings and another under the shuttered area on the nose for pitch control. Source: &lt;a href=&quot;http://www.aero-web.org/specs/ryan/xv-5a.htm&quot;&gt;http://www.aero-web.org/specs/ryan/xv-5a.htm&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;...there aren't any non-MAV examples around today that I know of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:&#xA;&lt;a href=&quot;https://theses.lib.vt.edu/theses/available/etd-05262005-170916/unrestricted/WGraf_Thesis_2005.pdf&quot;&gt;https://theses.lib.vt.edu/theses/available/etd-05262005-170916/unrestricted/WGraf_Thesis_2005.pdf&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14720" LastEditorUserId="14720" LastEditDate="2016-05-10T01:48:44.670" LastActivityDate="2016-05-10T01:48:44.670" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27431" PostTypeId="2" ParentId="27422" CreationDate="2016-05-08T04:01:59.563" Score="19" Body="&lt;p&gt;There are a few very practical reasons why turbine engines use inner shafts/spools. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, jet engine spools are very high speed rotating parts, this means they are subjected to high amounts of centripetal force. Centripetal force is calculated by $F=mr\omega ^2$ were F is Force, m is mass, r is radius of gyration and $\omega$ is angular velocity. So obviously the larger the radius of gyration the higher the forces that the rotors must carry. To reduce the radius of gyration manufacturers try to push the mass of the rotors as close to the centerline of the engine as possible. In the picture below (&lt;a href=&quot;https://www.google.com/patents/US8126628&quot;&gt;source&lt;/a&gt;) I have circled the HPC, HPT and LPT rotors. You can see how they are very thin under the blades and then have a large bulb very close to the engine centerline. Moving all of this mass towards the centerline, lowers the radius of gyration, and thus reduces the centripetal force. By reducing the centripetal force, you can reduce the strength of the rotors as well, since they don't have to carry as much load. This allows you to remove mass from the rotors, further reducing the centripetal force and overall weight of the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ritJu.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ritJu.png&quot; alt=&quot;Rotors&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next, you want the bearings to be as small as possible. This is because as the radius of a bearing increases the linear velocity of it also increases, via this equation: $v=\omega r$. The faster the linear velocity the higher the wear, the greater the friction and greater the heat generation. So there is a push to make the bearings as small as possible given other constraints. In the image below I have circled the bearings, the red circles are on the low pressure spool bearings, while the blue circles are the high pressure spool bearings. This isn't always done, but it is becoming very common for the aft high pressure bearing to actual ride on the low pressure shaft. Typically these shafts spin in the same direction, so the bearing speed is reduced by this equation $\omega_{AftHPbearing}=\omega_{HP}-\omega_{LP}$. Bearing friction reduces the efficiency of the engine, and bearing wear is a significant maintenance driver. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/3Olg0.png&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/3Olg0.png&quot; alt=&quot;Bearings&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(This is getting long so I am going to truncate the rest) There would be many other issues as well, such of blade mounting (dovetails in compression instead of tension), blade design (compression instead of tension), possible increase in leakage paths, containment, stator structure design (now all of your stators are attached to a stationary shaft that can only be supported at the ends), control of variable stator vanes, getting the fuel into the combustor, how do mount the engine, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: Just reread the question and realized you were also talking about making the combustor bigger. Modern combustors are getting smaller and are much smaller than they were in the original jet engines. You can also see in the pictures above, they already don't use all of the space available to them and if they needed more space the arm (shaft) connecting the HPT and HPC could be lowered some more.  &lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2016-05-08T04:16:56.497" LastActivityDate="2016-05-08T04:16:56.497" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27432" PostTypeId="2" ParentId="27401" CreationDate="2016-05-08T08:03:36.757" Score="1" Body="&lt;p&gt;The limits you are asking about have been pushed by the antonov. Anything bigger than that is certainly possible but not very much economical and may not be safe. While the global economy is in melting ice and a few solid patches here and there it would be a very unsuitable experiment to justify. Rather diverting the funds to improving the current airplanes may have a better result compared to an increase in size. &lt;/p&gt;&#xA;" OwnerUserId="14839" LastActivityDate="2016-05-08T08:03:36.757" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27433" PostTypeId="1" AcceptedAnswerId="27453" CreationDate="2016-05-08T08:47:11.170" Score="5" ViewCount="169" Body="&lt;p&gt;In the movement area at a controlled airport, I would assume any airworthy aircraft is automatically eligible to make requests to enter into, exit from, transit through movement areas, for the purpose of aviation related activity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about the other ground vehicles and pedestrians? Do they need some  special permit, or can simply make requests like a crew member?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2016-05-09T18:47:21.150" Title="What are the regulations for non-aircraft targets in airport movement area?" Tags="&lt;faa-regulations&gt;&lt;ground-operations&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27434" PostTypeId="1" CreationDate="2016-05-08T09:26:53.737" Score="6" ViewCount="3639" Body="&lt;p&gt;I've noticed some variation between loadsheet weights and FAC (Flight Augmentation Computer) calculated weight. That's of course normal, since loadsheet is calculated with standard weights and FAC calculates the weight from alpha and speed (at least as far as I know).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Question:&lt;/strong&gt; Does anyone have any information about the correctness and reliability of the FAC calculated gross-weight?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also interested in how exactly, and with what parameters, the FAC calculates it.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastEditorUserId="8321" LastEditDate="2016-05-09T07:53:04.823" LastActivityDate="2017-09-07T12:30:17.113" Title="How reliable is the Airbus FAC calculated gross-weight?" Tags="&lt;airbus&gt;&lt;airbus-a320&gt;&lt;weight-and-balance&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27435" PostTypeId="2" ParentId="2570" CreationDate="2016-05-08T13:56:22.917" Score="3" Body="&lt;p&gt;In theory, yes it is possible to do so.  It all depends on the aircraft type, approach speeds, sea and weather conditions, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the end of the Vietnam War, a South Vietnamsee refugee landed an OV-1 Bird Dog on the deck of the USS Midway (CV-41).  So, yes light airplanes have made unarrested landings on carriers in the past.  If your in a light airplane with a stall speed around 30kts and very proficient on your short field landings, this should be no sweat, provided the ship can steam either at, or into the prevailing wind at 30 or so kts.  If you're flying a dedicated bush airplane eg an Aviat Husky, Carbon Cub, etc designed for STOL operations, it may even be possible to stick a 3-wire (touch down and hold the main wheels in the third cross deck pendant full stop) under these conditions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Larger, heavier aircraft have faster approach speeds and need considerably more runway to stop on.  The CE-350 Corvalis mentioned above is going to require around 1500-2000 ft to land depending on ambient atmospheric conditions at sea level and calm winds, provided you can fly a short field right by the book.  Even with a 30kt headwind, you're looking at an 1100 ft or so of ground roll, making an unarrested landing on a carrier impractical.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there was no other option available to you, the deck hands could rig the barricade - a device which looks something like a tennis court net on steroids.  Granted this device was designed to stop aircraft 10-20 times the weight of a Corvalis at nearly twice the approach speed and I don't know if the arresting gear attached to it have settings available for smaller lighter aircraft.  If it doesn't, it could cause serious structural damage to your airplane, possibly making things worse.  Maybe that's better than ditching alongside the ship, maybe not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another factor would be the sea itself.  Carriers are not fixed airfields and in rough seas, the deck lists, pitches, and rolls considerably - think of a 100,000 ton cork bobbing in the ocean - making approaches quite dangerous for neophyte pilots.  Rough swellscouldbreak the gear off or do other structural damage during a round out, or cause the pilot to strike the round out, etc.  but if there was no other alternative, it's a risk you would have to take.&lt;/p&gt;&#xA;" OwnerUserId="14843" LastActivityDate="2016-05-08T13:56:22.917" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27436" PostTypeId="1" AcceptedAnswerId="29505" CreationDate="2016-05-08T14:53:07.933" Score="10" ViewCount="380" Body="&lt;p&gt;I have been seeking an intercom unit for a Cessna 172N that has four seats but only two headset jacks, and I would like my rear passengers to be able to communicate without yelling.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation intercoms have external radio transmit switches, but the airplane also has its own built-in radio transmit system.  How does the transmit function trigger in this type of system?  Do they send a certain audio signal frequency or tone to the COM stack that tells it to transmit?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are most intercoms universally compatible with all com stacks if they use the same plug types?&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-08T20:39:22.603" LastActivityDate="2016-06-22T06:48:22.677" Title="Do aviation intercoms have a standardized compatibility with radio stacks?" Tags="&lt;radio-communications&gt;&lt;avionics&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27438" PostTypeId="1" AcceptedAnswerId="27439" CreationDate="2016-05-08T16:45:01.530" Score="9" ViewCount="1384" Body="&lt;p&gt;From what i've seen delta wings are more appropriate to supersonic designs, and have poor lift/drag ratios at subsonic speeds. The Starship had a cruise speed of 300 kn, so what was the reasoning behind the wing design?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I know that the engine on the back/pusher configuration puts the CoG further back, so you would want to put the wings behind, but the Piaggio Avanti does the same with conventional wings.&lt;/p&gt;&#xA;" OwnerUserId="14683" LastActivityDate="2018-03-05T00:58:20.253" Title="Why did the Beechcraft Starship use a delta wing?" Tags="&lt;delta-wing&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27439" PostTypeId="2" ParentId="27438" CreationDate="2016-05-08T17:54:14.647" Score="13" Body="&lt;p&gt;Because it was something of a &lt;a href=&quot;https://en.wikipedia.org/wiki/Burt_Rutan&quot; rel=&quot;noreferrer&quot;&gt;Burt Rutan&lt;/a&gt; trademark since his early days. His first designs, the VariViggen and VariEze, had such a wing already, and apparently he saw no reason to optimize the wing of the Starship.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/1OsQj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/1OsQj.jpg&quot; alt=&quot;Rutan VariEze in flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rutan VariEze in flight (picture &lt;a href=&quot;http://v2.ez.org/images/gy1104-15.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only true innovation was a variable geometry canard, which he even &lt;a href=&quot;https://www.google.de/patents/US4641800&quot; rel=&quot;noreferrer&quot;&gt;patented&lt;/a&gt;. Being only 85% scale, the performance of the Starship prototype was formidable, but once the real production aircraft had been designed with full compliance to airworthiness regulations, the Beech Starship turned out to be less impressive. The additional wetted surface produced more friction drag. Piaggio's design is clearly superior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, the idea behind the variable geometry canard was sound: In the landing configuration it would balance the additional lift from the fowler flaps on the wing. But the whole mechanism cost more in weight than the reduction in drag during cruise could save.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8uq2g.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8uq2g.png&quot; alt=&quot;Drawing from US Patent 4641800&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Drawing from US Patent 4641800.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-05-08T17:54:14.647" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27441" PostTypeId="1" AcceptedAnswerId="27442" CreationDate="2016-05-08T20:41:44.153" Score="5" ViewCount="193" Body="&lt;p&gt;I would like to know how far above and below a wing's surface an observer must look in order to see no change to the airflow. Not simply visually but mechanically, assuming a perfect scenario. I am not particularly adept at mathematics, so if there is a rule of thumb, or a general upper boundary, that would suffice for the figure I need.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a visual representation, a wind tunnel with smoke trails. At some point distant from the top and bottom of the wing in the tunnel, all flow lines will be identical again, implying that wings have an area of effect. How far is this point from each respective surface?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way to ask would be to say how far apart must biplane wings be (in a perfect scenario) for them to have no effect on each other?&lt;/p&gt;&#xA;" OwnerUserId="14849" LastEditorUserId="1467" LastEditDate="2016-05-08T20:59:34.710" LastActivityDate="2016-05-16T23:27:20.337" Title="How far away from a wing's surface does the air stream remain unaffected?" Tags="&lt;wing&gt;&lt;lift&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27442" PostTypeId="2" ParentId="27441" CreationDate="2016-05-08T21:30:15.293" Score="7" Body="&lt;p&gt;A precise answer would be: Only outside of the supersonic shock cone. In subsonic flow the change has unlimited range, but dies down with the inverse of the distance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A mathematical description is possible with the &lt;a href=&quot;https://en.wikipedia.org/wiki/Biot%E2%80%93Savart_law&quot; rel=&quot;nofollow&quot;&gt;Biot-Savart law&lt;/a&gt;. It was first formulated for calculating the magnetic field induced by a current, but can equally well be applied to aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now it depends on how much error you still accept. If you need the interference-free distance between two biplane wings, express that distance in multiples of the wingspan - that is how it scales. A few wingspans of vertical separation should be enough to make the interference between wings negligible. In flow direction the distance must be much larger: Munk's displacement law postulates that in inviscid aerodynamics the distance in flow direction between two wings makes no difference. In reality, air traffic control requires a &lt;a href=&quot;https://en.wikipedia.org/wiki/Wake_turbulence#Wake_vortex_separation&quot; rel=&quot;nofollow&quot;&gt;separation of up to 8 nautical miles&lt;/a&gt; between heavy airplanes for the turbulence to die down or be washed away by wind.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-09T19:51:30.080" LastActivityDate="2016-05-09T19:51:30.080" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27443" PostTypeId="2" ParentId="13132" CreationDate="2016-05-08T23:37:17.533" Score="0" Body="&lt;p&gt;its is called a flare, it is a 5-10 degree pull to slow the aircraft down and put the rear wheels on the ground.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Rear landing gear is put down first because there at the center of mass (CoM), It is also smoother and safer. It is safer because the front landing gear is not made to hold the whole wait of the aircraft. (EX. the airbus A380 has many Rear Gear but only 1 front gear(&lt;a href=&quot;http://avimotive.com/wp-content/uploads/2016/01/a.jpg&quot; rel=&quot;nofollow&quot;&gt;http://avimotive.com/wp-content/uploads/2016/01/a.jpg&lt;/a&gt;))&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is smoother because It slows the sink rate.&lt;/p&gt;&#xA;" OwnerUserId="14851" LastActivityDate="2016-05-08T23:37:17.533" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27444" PostTypeId="2" ParentId="27377" CreationDate="2016-05-09T09:20:33.750" Score="2" Body="&lt;p&gt;Depending on your drone, the drone will probably stop moving and land safely. Or it will continue flying until there is no power left. There are no regulations about this and this question can only be answered if you try it out yourself or ask this to your manufacturer.   &lt;/p&gt;&#xA;" OwnerUserId="14237" LastActivityDate="2016-05-09T09:20:33.750" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27445" PostTypeId="1" AcceptedAnswerId="27448" CreationDate="2016-05-09T10:12:08.887" Score="25" ViewCount="4833" Body="&lt;p&gt;In the shock wave of the next image (in a blunt body)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/29Zbb.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/29Zbb.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why the wavefront is in front of the object? It does not assume that if the object travels faster than the speed of sound wave front should be just touching the object that causes it ?&lt;/p&gt;&#xA;" OwnerUserId="11221" LastEditorUserId="1467" LastEditDate="2016-05-09T10:54:26.810" LastActivityDate="2016-05-16T13:13:22.470" Title="Why does this shockwave not touch the body that creates it?" Tags="&lt;fluid-mechanics&gt;&lt;shock-waves&gt;" AnswerCount="3" CommentCount="4" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27446" PostTypeId="1" AcceptedAnswerId="27460" CreationDate="2016-05-09T10:54:47.627" Score="8" ViewCount="6758" Body="&lt;p&gt;This is the usual view of a two-spool turbine engine:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/U4Qe5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/U4Qe5.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(From &lt;a href=&quot;http://usedstuff001.blogspot.fr/2012_10_01_archive.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know if &lt;em&gt;shaft casing&lt;/em&gt; or &lt;em&gt;hub&lt;/em&gt; are correct names, this is the external skin of the volume around the N1/N2 shafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can't find a description of how this volume is made. It seems descriptions omit a number of elements for simplicity, for instance, this drawing from &lt;a href=&quot;https://aviation.stackexchange.com/questions/27422/compressor-turbine-why-a-shaft-and-not-kind-of-a-rotating-drum#27431&quot;&gt;this answer&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7L4Qr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7L4Qr.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.google.tl/patents/US20090037035&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My interest is about the green area. It's not clear to me:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How airtightness is obtained overall on both sides of the core air duct?&lt;/li&gt;&#xA;&lt;li&gt;How airtightness is obtained in locations like 1, 4 or 5 when rotating elements meet stationary (or N1) elements?&lt;/li&gt;&#xA;&lt;li&gt;How torque is transmitted from the HP turbine to blade 2? or how elements (like 3) between the turbine and the compressor discs are assembled together to form a rigid wall/pipe?&lt;/li&gt;&#xA;&lt;li&gt;How stators (like in 3) are fixed?&lt;/li&gt;&#xA;&lt;li&gt;Why the central hole size varies for the rotor discs (like 2)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Cross-sections would help but I can't find ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bottom line: Without necessarily entering into details (but they are welcome), could you provide an overall description of how this &quot;hub&quot; is assembled, particularly the HP part?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-11-11T22:11:39.460" Title="How is the central hub / shaft casing of a two-spool jet engine assembled?" Tags="&lt;turbine&gt;&lt;engine-design&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27448" PostTypeId="2" ParentId="27445" CreationDate="2016-05-09T11:47:06.290" Score="30" Body="&lt;p&gt;After passing through the shock wave, the air still has to evade the body. If the shock-wave touched the body, the air would have to escape through infinitely thin space at infinitely high pressure and it obviously can't do that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So behind the shockwave there is a boundary layer (called shock layer) in which the air is moving with the body and flows, under high pressure, to the sides where it can escape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The blunter the body, the thicker the boundary layer, because the air must cover longer distance to the sides and takes longer to do that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the high pressure between the shock and the body causes a lot of drag, which is why sharp nose and leading edges are preferred for supersonic flight.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-05-09T19:40:43.740" LastActivityDate="2016-05-09T19:40:43.740" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27449" PostTypeId="2" ParentId="27445" CreationDate="2016-05-09T12:22:55.413" Score="10" Body="&lt;p&gt;In case of an infinestimally thin body in supersonic flow, the disturbances created propogate as Mach waves. However, as the the thickness of the body increases, the flow has to physically turn away from the object after the shock wave.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if a wedge at an angle $\theta$ is placed in supersonic flow, the fluid has to turn by that angle after passing through the compression shock (so that the flow is along the body). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a given upstream Mach number $M_{1}$, there is a maximum turning angle $\theta_{max}$, beyond which an oblique shock is physically not possible and the shock wave gets detached i.e. it is physically not possible to turn the flow suddenly while conserving mass, momentum and energy. The flow 'solves' this problem by detaching the shock in front of the body.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-05-09T12:22:55.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27450" PostTypeId="1" CreationDate="2016-05-09T15:12:06.217" Score="3" ViewCount="471" Body="&lt;p&gt;I'm curious if anybody can provide a &lt;strong&gt;rough price estimate for a commercial aviation ULB like those used on Black Boxes&lt;/strong&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Area of interest: Europe i.e. Euros, EASA CS-25.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;(For instance the RJI ULB-362 or the Dukane DK-120, but any equivalent is good)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="790" LastActivityDate="2016-05-09T16:12:27.073" Title="How much does a Black Box Underwater Locator Beacon (ULB) cost?" Tags="&lt;flight-data-recorder&gt;&lt;cost&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27451" PostTypeId="2" ParentId="27450" CreationDate="2016-05-09T16:12:27.073" Score="3" Body="&lt;p&gt;There is one listed here on &lt;a href=&quot;http://www.ebay.com/itm/like/201468749609?lpid=82&amp;amp;chn=ps&amp;amp;ul_noapp=true&quot; rel=&quot;nofollow&quot;&gt;Ebay for $750&lt;/a&gt;. Some of the makers like &lt;a href=&quot;http://l-3ar.com/tso-c121b/SIL_L-3AR-2015-0005_90-Day_Beacon_retrofit_kits_rev-.pdf&quot; rel=&quot;nofollow&quot;&gt;L-3 list contact info&lt;/a&gt; for getting pricing, all of the other sales sites I am finding look like you need to submit for a price quote. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-09T16:12:27.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27452" PostTypeId="1" CreationDate="2016-05-09T18:25:41.487" Score="4" ViewCount="1191" Body="&lt;p&gt;(I was trying to understand the longitudinal stability of aircraft and how it is related to elevator)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I pull the stick back by, say 2 inches, will it have the same affect as trimming the horizontal stabilizer to make the aircraft fly at that angle of attack?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I mean, does setting the elevator at constant 2 degree will make the aircraft swing its nose up as long as the stick is held or does it trim itself to the new angle of attack and ride steadily in its new position?&lt;/p&gt;&#xA;" OwnerUserId="11517" LastEditorUserId="19" LastEditDate="2016-07-28T16:39:04.153" LastActivityDate="2020-08-21T06:03:43.653" Title="Is setting elevator to certain angle equal to trimming the horizontal stabilizer?" Tags="&lt;stability&gt;&lt;trim&gt;&lt;elevator&gt;&lt;horizontal-stabilizer&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27453" PostTypeId="2" ParentId="27433" CreationDate="2016-05-09T18:32:13.477" Score="3" Body="&lt;p&gt;Ground vehicles are really problematic at an airport. The problem is not so much a matter of regulation as a problem that the people driving the vehicles sometimes are unfamiliar with flight processes so they create hazards without really understanding the danger they are creating. The &quot;regulations&quot; are that nobody is supposed to be on taxiways or runways without approval whatever that means, but since the FAA cannot revoke the license of somebody that does not have a license, it's a toothless rule. Also, the typical runway intruder does not even have a radio, so getting approval is problematic for them. Cops are the worst offenders. I have seen some very dangerous situations evolve from ignorant cops with no idea what they are doing just driving onto runways acting like they are god or something.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The main way the FAA interfaces to the ground control problem is to &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/media/Ground_Vehicle_Guide_Proof_Final.pdf&quot; rel=&quot;nofollow&quot;&gt;publish a lot of safety guidelines&lt;/a&gt; hoping that somebody will read them. Some airports have elaborate safety training for ground personnel, but the main risks usually come from untrained personnel at smaller airports where there is little or no training.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is one of the main reasons why most airports work hard to get good fencing set up, so some bozo does not drive onto the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, ground control takes care of authorizing vehicle movement and utility trucks are supposed to coordinate their actions with ground control. In untowered airports, utility trucks are supposed to call on CTAF to notify nearby pilots what they are doing, but unfortunately most do not have radios. Once I was landing and there was some truck on the side of the runway because the guy was removing a turtle or something. The truck had flashing lights so it was easy to see luckily.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-05-09T18:47:21.150" LastActivityDate="2016-05-09T18:47:21.150" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27454" PostTypeId="2" ParentId="27377" CreationDate="2016-05-09T19:06:23.690" Score="3" Body="&lt;p&gt;Let's take it from the top: &lt;strong&gt;it depends on the drone&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regular, off the shelf hobby drones, might just turn off and then fall to their doom. Some more expensive ones, might have a feature to safely land (instead of dropping like a rock).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering military ones, it all depends on the programming and the manufacturer. Some drones have parachutes, so that could aid them when they run out of juice.&lt;/p&gt;&#xA;" OwnerUserId="14857" LastActivityDate="2016-05-09T19:06:23.690" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27455" PostTypeId="1" AcceptedAnswerId="27459" CreationDate="2016-05-09T19:53:12.093" Score="0" ViewCount="833" Body="&lt;p&gt;Which operating systems run the In-Flight Entertainment Systems on commercial passenger aircraft?&lt;/p&gt;&#xA;" OwnerUserId="14858" LastEditorUserId="6886" LastEditDate="2016-05-09T23:36:20.013" LastActivityDate="2016-05-09T23:36:20.013" Title="Which operating systems do entertainment systems run on?" Tags="&lt;inflight-entertainment&gt;" AnswerCount="1" CommentCount="8" ClosedDate="2016-05-10T03:32:29.963" ContentLicense="CC BY-SA 3.0" />
  <row Id="27456" PostTypeId="2" ParentId="27452" CreationDate="2016-05-09T20:14:01.003" Score="6" Body="&lt;p&gt;Yes, both are equal for small angle changes. Exceptions do apply, &lt;a href=&quot;https://aviation.stackexchange.com/questions/5003/what-control-issues-did-the-x-1-have-to-overcome-to-achieve-supersonic-flight/5004#5004&quot;&gt;especially in transsonic flow&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Both changing the stabilizer incidence and the elevator deflection will change the lift distribution between wing and tail surfaces and will trim the aircraft for a different angle of attack. Changing the incidence gives the empennage a new angle of attack while changing the deflection will change the camber (and with it the zero-lift angle of attack) and the angle of attack of the empennage. For small deflections the effect is the same; however, the change in stabilizer incidence is smaller than the elevator deflection change for the same effect in proportion to the square root of the relative elevator chord.&lt;/p&gt;&#xA;&lt;p&gt;Say you change the stabilizer nose-down rsp. the elevator trailing edge up. The tail will produce less lift / more downforce and the aircraft pitches up. Now the angle of attack of both the wing and the tail will increase which increases lift on both until the distribution of lift between both is as before - after all, we did not change the position of the center of gravity, and the angle of attack will change until the center of pressure is exactly below or above the center of gravity again. There the aircraft finds a new equilibrium speed and will fly on in its new attitude.&lt;/p&gt;&#xA;&lt;p&gt;Nevertheless, depending on the initial trim point, the aircraft will now climb or sink because the thrust does not match the new drag at the new trim point. The aircraft will settle at a new vertical speed, too.&lt;/p&gt;&#xA;&lt;p&gt;Before you think that one of them would be enough: Both are needed because each is a specialist for tasks that the other would handle poorly:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The elevator moves quickly and needs small actuation forces, so it is built for manoeuvring or gust response.&lt;/li&gt;&#xA;&lt;li&gt;The stabilizer moves slowly but can effect much higher lift changes. It is meant for retrimming during or after changes in configuration. Deflection of the lift devices on the wing will shift the center of pressure backwards, so in order to balance all lift forces, the tail now needs to produce massive downforce, something only the adjustable stabilizer is capable of.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21114/why-do-some-fighter-jets-have-movable-horizontal-stabilizer-instead-of-elevators/21130#21130&quot;&gt;This answer&lt;/a&gt; covers these aspects in more detail.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2020-08-14T18:33:05.547" LastActivityDate="2020-08-14T18:33:05.547" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="27457" PostTypeId="1" AcceptedAnswerId="27458" CreationDate="2016-05-09T21:41:13.290" Score="24" ViewCount="5101" Body="&lt;p&gt;The S-70 Black Hawk has some kind of movable surfaces on its tail, look:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/PNAYa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PNAYa.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;http://m.airliners.net/photo/detail/id/2816999&quot; rel=&quot;noreferrer&quot;&gt;Airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They look like &quot;elevators&quot; on airplanes. Does anybody know what are these things for?&lt;/p&gt;&#xA;" OwnerUserId="13197" LastEditorUserId="13197" LastEditDate="2016-05-09T23:35:46.597" LastActivityDate="2016-10-13T18:42:39.030" Title="What is the purpose of fins on the empennage on some helicopters?" Tags="&lt;aerodynamics&gt;&lt;helicopter&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27458" PostTypeId="2" ParentId="27457" CreationDate="2016-05-09T22:47:45.393" Score="38" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Stabilator&quot; rel=&quot;nofollow&quot;&gt;It's a stabilator&lt;/a&gt; used on the &lt;a href=&quot;http://www.aviastar.org/helicopters_eng/sik_s-70.php&quot; rel=&quot;nofollow&quot;&gt;Blackhawk&lt;/a&gt; to reduce attitude changes with airspeed and to offset pitch effects from the tail rotor.  It's part of the automatic flight control system.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All &quot;traditional&quot; design helicopters have horizontal stabilisers to push the tail down to reduce the nose down pitch in forward flight.  Fixed ones are normally trimmed to provide a more level deck at typical cruise speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the Blackhawk, it's fully movable. It is automatically adjusted according to collective pitch and airspeed. &lt;a href=&quot;http://aasf1-ny.org/4-Standards/Documents/PUBLICATIONS/StudentHandouts/UH60%20AFCS.pdf&quot; rel=&quot;nofollow&quot;&gt;From here&lt;/a&gt;, the benefits are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Align stabilator and main rotor downwash in low speed flight to minimize nose up attitude resulting from downwash.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Provide collective coupling to minimize pitch attitude excursions due to collective inputs from the pilot.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Decrease angle of incidence with increased airspeed to improve static stability.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Provide sideslip to pitch coupling to reduce susceptibility to gusts.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Provide pitch rate feedback to improve dynamic stability. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-10-13T18:42:39.030" LastActivityDate="2016-10-13T18:42:39.030" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27459" PostTypeId="2" ParentId="27455" CreationDate="2016-05-09T23:09:54.220" Score="1" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.linuxinsider.com/story/65541.html&quot; rel=&quot;nofollow&quot;&gt;this article&lt;/a&gt;, Linux is at least one of the main contenders in the space, Wikipedia also makes a &lt;a href=&quot;https://en.wikipedia.org/wiki/In-flight_entertainment&quot; rel=&quot;nofollow&quot;&gt;lose reference to Linux&lt;/a&gt; and &lt;a href=&quot;http://www.engadget.com/2007/02/10/mega-hands-on-virgin-americas-airbus-a320-with-red-in-flight-e/&quot; rel=&quot;nofollow&quot;&gt;cites this article as the source&lt;/a&gt;. Here is some &lt;a href=&quot;http://oduinn.com/blog/2012/09/20/linux-on-a-boeing-777/&quot; rel=&quot;nofollow&quot;&gt;photographic evidence that its Linux as well&lt;/a&gt;. Although I'm sure it varies by maker it seems that Linux is at least one of the main players. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="12220" LastEditDate="2016-05-09T23:16:02.153" LastActivityDate="2016-05-09T23:16:02.153" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27460" PostTypeId="2" ParentId="27446" CreationDate="2016-05-10T01:17:24.803" Score="11" Body="&lt;p&gt;The first thing to know when designing jet engines, is everything leaks. But the OD of the engine core is generally pretty tight. This is achieved using large solid structural pieces, for example the entire LPT outter casing is generally one piece. These large pieces are bolted together with an excessive number of bolts to make them very tight. Any penetrations will have various types of seals and gaskets, as well as high clamping forces. Although the outer case is pretty tight, the cavity between the core case and the bypass duct is still actively purged with air from the low pressure compressor (labelled as undercowl cooling on the image below). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;GE90 Engine Airflow Diagram (This is actually a widely available training poster but I stole it from &lt;a href=&quot;http://www.twirpx.com/file/355593/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;, you can find similar for just about every engine)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/zhvGs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zhvGs.jpg&quot; alt=&quot;GE90Airflow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the inner side of the core, this is where literally everything leaks. As you can see in the picture above, Stage 1 (S1) High Pressure Compressor (HPC) bleed air is used to actively purge the cavity under the Low Pressure Compressor (LPC) and early stages of the HPC. It is then plumbed though a small duct around the low pressure shaft to the Low Pressure Turbine (LPT) (zoom in on the image and flow the arrows in the yellow fill). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your location number 1 is the split between the LPC rotors (spinning) and the Fan Frame (stationary). Your location number 5 is the split between the LPT (spinning) and the turbine rear frame (stationary). In these locations (and in all gaps in the ID of the core) the air is allowed to flow back into the flow path. The purge air must be at a higher pressure the flow path air, and allowing it to flow back into the main flow path actively purges these gaps and in the turbine prevents hotter gas path air from backflowing into the rotor cavity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your location 4 is at the end of the compressor and beginning of the combustor and is known as Compressor Discharge Pressure (CDP) air. The image below (&lt;a href=&quot;https://en.wikipedia.org/wiki/Combustor&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) shows what is going on here. A faction of the air is directed directly into the combustor through the fuel nozzle assembly, while the rest bypasses and is used as dilution air, as well as combustor liner cooling. Another faction is taken off the OD to cool the S1 HPT Vane and Shroud, while a larger fraction is taken off the ID to cool the S1 HPT Vane, Blade and rotor, as well as actively purge the gap between the S1 blade and vane. If this cooling air was ever lost, the HPT would literally oxidize/melt/creep away in a matter of seconds. The gap at location 4 is sized so the correct about of flow goes into the combustor dome and the right amount bypasses the fuel nozzles. Note that in ultra modern combustors, the diluation holes no longer exist and a much larger fraction of air enters at the fuel nozzle location.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ayo7I.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ayo7I.png&quot; alt=&quot;Combustor Airflow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torque is transferred from the HPT to the HPC through the spool arms (basically a shaft), which is what connects each rotor to each other. I have highlighted this in red in the image below. The full spool is created in multiple ways. Some of the HPC rotors are forged together into sub-spools. Some of these sub-spools are welded together (becoming more common) and then some joints are done with bolts. In the second image below, is the HPC spool for the CFM56, I have circled the bolted connections. Bolts are generally used when there is a change in materials so welding can't be done. The first couple of stages will be Ti, while the later stages are a Nickle based super(ish) alloy. The HPT rotor is a Nickle based super alloy but is generally being pushed to the limit too much to be welded. When it is all put together, you have a very stiff shaft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2Ennf.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2Ennf.png&quot; alt=&quot;HPShaft&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/2nl1b.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2nl1b.png&quot; alt=&quot;HPCSpool&quot;&gt;&lt;/a&gt; (&lt;a href=&quot;https://fenix.tecnico.ulisboa.pt/downloadFile/844820067123432/Tese.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source PDF&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The stators are attached to the outer casing. Generally there is a circumferential slot in the case, the stators slide into this slot. Generally the stators are brazed together in multi-vane assembles to reduce air leakage. There is also a &lt;a href=&quot;https://en.wikipedia.org/wiki/Labyrinth_seal&quot; rel=&quot;noreferrer&quot;&gt;labyrinth seal&lt;/a&gt; on the ID of each stator to reduce air leakage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The S1 and S2 HPC rotors (your location 2) have a larger ID than the other rotors so they can fit over the bearing race when they are unbolted from the spool and to allow tool access to the bolts. The S3 rotor is the largest because it support the arm going to the bearing, a still largish blade and the bolted joint of the spool join. As you go aft the rotors get a little smaller because they support smaller blades, but that is counter acted by raising temperatures that reduce the material capabilities.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall engine assembly (&lt;a href=&quot;https://www.youtube.com/watch?v=XNS3uX9nIAE&quot; rel=&quot;noreferrer&quot;&gt;Youtube Video of GEnx-2B being assembled&lt;/a&gt;). Depending on the engine it'll be assembled from Fan back or LPT forward. So from LPT forward (Very simplified). First take the built up LPT module and attach the LP shaft (aka fan shaft/fan mid shaft). Next, you would build up the HP section including outer casing seperately, then slide this onto the LPT, attach the HPT outer casing to the LPT case with an excessive number of bolts, if there is a mid turbine frame it would be installed between the two turbines with bolted joints on both sides. Then you install the fan frame to the HPC case and then the fan spool to in the LP shaft and the fan case to the fan frame. With the right tools, it all slides together pretty easily. One way the LP shaft is connected to the LPT and Fan Spool through splined connections and a large coupling nut is installed on each end of the shaft to prevent the splines from backing off. Sometimes the shaft is bolted directly to the LPT or Fan spool directly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sorry for being so long winded, but I hope that answers your questions. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is one more flow diagram for reference (&lt;a href=&quot;http://i308.photobucket.com/albums/kk337/afoggyeye/Engine%20and%20drydock/LM2500Airflow.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;):&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Gxnv6.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Gxnv6.jpg&quot; alt=&quot;LM2500 Flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2016-05-11T00:22:22.643" LastActivityDate="2016-05-11T00:22:22.643" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27461" PostTypeId="1" CreationDate="2016-05-10T04:44:36.603" Score="16" ViewCount="5898" Body="&lt;p&gt;I've lived near several airports and have grown accustomed to a certain noise a jet plane makes when passing overhead: a swooping sound, very bass-heavy, that dives rapidly in pitch, maybe 1.5 seconds in duration. It happens toward the very beginning of the plane's audibility and is followed by the normal sound of the jet passing above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it simply the Doppler effect as the plane passes overhead and its noise rapidly changes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or is there a mechanism on the airframe whose actuation on an approach might make this sound? Sometimes the same plane makes this sound more than once, which makes me think it isn't simply the Doppler effect.&lt;/p&gt;&#xA;" OwnerUserId="12970" LastEditorUserId="12970" LastEditDate="2016-05-10T16:21:52.050" LastActivityDate="2018-08-31T05:48:26.990" Title="What makes the swooping noise when a jet flies overhead?" Tags="&lt;commercial-aviation&gt;&lt;jet-engine&gt;&lt;approach&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27462" PostTypeId="2" ParentId="9703" CreationDate="2016-05-10T07:17:05.577" Score="2" Body="&lt;p&gt;You can start an f-22 in about 2 minutes or less. The procedure is&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Master Batt. &lt;/li&gt;&#xA;&lt;li&gt;APU(Auxiliary Power Unit)&lt;/li&gt;&#xA;&lt;li&gt;Flip 2 generator switches&lt;/li&gt;&#xA;&lt;li&gt;flip nav and position lights as required for mission&lt;/li&gt;&#xA;&lt;li&gt;Make sure fuel switches are set right&lt;/li&gt;&#xA;&lt;li&gt;Wait a couple seconds for APU to finish start up&lt;/li&gt;&#xA;&lt;li&gt;push throttles to idle      &lt;/li&gt;&#xA;&lt;li&gt;configure MFDs as needed as engines spin up.&lt;/li&gt;&#xA;&lt;li&gt;taxi to runway&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="14864" LastActivityDate="2016-05-10T07:17:05.577" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27464" PostTypeId="2" ParentId="27445" CreationDate="2016-05-10T10:34:11.247" Score="7" Body="&lt;p&gt;Perhaps, at the root of your question, there is a misunderstanding of the nature of a shock wave. A shock wave is a surface, an ensemble of points, where the properties of the gas change discontinuously (it is not the only surface with this characteristic, but the other class, that of &lt;em&gt;contact discontinuities&lt;/em&gt; is &lt;em&gt;absolutely unstable&lt;/em&gt;, and quickly disappears). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus a shock wave has gas on &lt;strong&gt;both&lt;/strong&gt; sides of it, by definition. Hence, it cannot touch the object, because there must be another layer of gas between the object and the shock wave. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But now your question can become: why must there be gas on &lt;strong&gt;both&lt;/strong&gt; sides of the shock wave? The reason is that fluid &lt;strong&gt;must&lt;/strong&gt; cross the shock wave, &lt;em&gt;i.e.&lt;/em&gt;  fluid goes continuously from the front to the back of the shock wave (discontinuous are the thermodynamic properties of the gas, and the component of the perpendicular speed across the shock wave, but otherwise gas move continuously from one side to the other). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there surfaces where matter does &lt;strong&gt;not&lt;/strong&gt; cross a surface of discontinuity? Yes, there are, and they are called &lt;em&gt;contact discontinuities&lt;/em&gt;, which, being absolutely unstable (the term &lt;em&gt;absolutely&lt;/em&gt; has a very special meaning in fluidodynamics), quickly disappear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second part of your question,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It does not assume that if the object travels faster than the speed of sound wave front should be just touching the object that causes it ?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;seems to indicate that you are thinking of a shock wave as a regular wave, hence the blunt object should catch up with it. Unfortunately, calling a shock wave a &lt;em&gt;wave&lt;/em&gt; is a historical relic, which betrays the fact that shock waves move supersonically with respect ot the fluid in which they propagate. In fact, there can be &lt;strong&gt;no&lt;/strong&gt; shock wave which moves sonically or slower, lest the second principle of thermodynamics be violated (Landau and Lifshitz's &lt;em&gt;Fluid Mechanics&lt;/em&gt; volume has a beautiful proof of this theorem, in full generality).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a matter of fact, we (could) take the above statements (in a quantitive form, mind you) and push them one step further: since the motion of the post-shock gas is slow (&lt;em&gt;i.e.&lt;/em&gt;, subsonic) with respect to both the shock wave and the blunt object, its flow away from the fore of the blunt object occurs slowly, so that more and more fluid is trapped between the shock wave and the object. More fluid means more counter-pressure, hence the the shock must be located further and further from the blunt object: it forms close to the tip of the blunt object, but then it drifts away from it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The truly cute feature of the picture above is the well-defined turbulent region in the object's wake...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As per &lt;em&gt;mins&lt;/em&gt;' request (see below), you can see it as follows. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The speed of sound arises when you consider the fate of small perturbations. Imagine for instance that you locally compress matter a tiny little bit, &lt;em&gt;i.e.&lt;/em&gt; you increase the density from $\rho$ to $\rho + \delta\!\rho$. In fluids, a higher density of a given fluid (= a smaller occupied volume) induces an extra pressure, so that, locally, $p\rightarrow p + \delta\!p$. So now you have a small volume whose pressure exceeds that of the surrounding medium: what happens? It obviously expands, &lt;em&gt;i.e.&lt;/em&gt; pushes away nearby matter in order to claim for itself the volume occupied by the surrounding medium. &lt;em&gt;Hence&lt;/em&gt;, a small increase in local density results in nearby matter having to move away, dislodged by the extra-density volume. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dislodged matter moves slowly, because the force acting on it is small: we assumed that the extra pressure is small compared to the average pressure, $\delta\!p \ll p$. However, the first dislodged parcel of fluid sits next to another (for the moment static) parcel of fluid, which itself must make room for the first parcel of fluid, giving rise to a second dislodged parcel of fluid, and so on. There will be $N \gg 1$ dislodged generations of parcels of fluids, all set in motion by the original compressed fluid element, and reached eventually by this chain of dislodgings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first sight, one might think that this chain of dislodging events goes only as fast as each parcel of fluid, which is very slow as we said above, but this is &lt;strong&gt;not&lt;/strong&gt; the case. The reason is that what we are asking is &lt;strong&gt;not&lt;/strong&gt; the speed at which is parcel of fluid is moving (slow, as stated above), but how long it takes for the $N$-th generation dislodging &lt;strong&gt;to begin&lt;/strong&gt;, not to complete. The speed of sound identifies the moment when the $N$-th generation dislodging begins, not ends, it identifies when the first perturbation arrives, not when it completes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This speed is much larger than the speed at which individual parcels move. When we have compressed the initial parcel, we have also heated it (compression leads to heating, in normal materials), hence the average molecule will have a higher-than-before temperature $T+\delta\!T$. As you clearly know, a molecule coming from a warmer region is slightly faster (in the average) than one from a colder region because $v \approx \sqrt{kT/m}$, &#xA;so that the first generation dislodged material will &lt;strong&gt;first&lt;/strong&gt; notice that it has a warmer (=greater pressure) neighbor when it is first reached by its hotter-than-average molecules, which travel at speed $\approx \sqrt{kT/m}$. Thus the speed with which the message &lt;em&gt;Slide over, you wimp&lt;/em&gt; travels is the same as that of the molecules from the warmer surroundings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;These hotter-than-average molecules from the hotter surrounding collide with the average local molecules, and transfer to them a bit of their extra energy, &lt;em&gt;i.e.&lt;/em&gt; local molecules are heated by the collisions from the original place of compression. Now these newly heated molecules will move out to the region of the 2-nd generation dislodged gas, and repeat the process again: the speed with which the &lt;em&gt;signal&lt;/em&gt; travels, &lt;em&gt;i.e.&lt;/em&gt; the first perception that the local gas must start moving, is again (actually, always) that of the molecules, $\approx \sqrt{kT/m}$. Hence the sound of speed is $c_s \approx \sqrt{kT/m}$.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the derivation above I have skipped some details, whose inclusion however only modifies $c_s$ to the extent of replacing the previous formula with $c_s = \sqrt{5 kT/2m}$. The real detail I left out is that, once compression occurs, in real fluids this does not necessarily lead to the maximum heating possible (which leads to the factor $5/2$ above), but it can be lower than that because some of the extra heat may be dissipated away &lt;strong&gt;before&lt;/strong&gt; the warmer-than-their-surrounding molecules have managed to reach their surroundings. If heat is dissipated (via viscosity, radiation, whatever) then it takes longer for the first-generation fluid to realize that the initial parcel of fluid has been compressed, because fewer of the molecules arriving to it are warmer than its own molecules. &lt;/p&gt;&#xA;" OwnerUserId="14866" LastEditorUserId="14866" LastEditDate="2016-05-16T13:13:22.470" LastActivityDate="2016-05-16T13:13:22.470" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27465" PostTypeId="2" ParentId="27461" CreationDate="2016-05-10T11:05:01.380" Score="14" Body="&lt;p&gt;The effect you noticed is the result of the combination of Doppler effect and sound absorption. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sound absorption in a fluid is proportional to &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$exp(- \alpha \nu^2 x)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;where $\alpha$ is a dimensional constant, $x$ is the traveled path, and $\nu$ is the sound frequency. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In its own reference frame, the airplane emits always the same sound, irrespective of whether it is approaching or receding from the observer. But for the observer, the frequency of a wave (which is $\nu_0$ in the plane frame) seems $\nu_a = \frac{\nu_0}{(1-v_j/c_s)}$ when the airplane is approaching, and $\nu_r = \frac{\nu_0}{(1+v_j/c_s)}$ when the plane is receding (here $c_s$ is the sound speed and $v_j$ the airplane's speed). Thus the perceived frequency jumps by a factor&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$F = \left(\frac{1+v_j/c_s}{1-v_j/c_s} \right)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that the absorption coefficient, at the time when the airplane is passing overhead (thus $x \approx H$, the plane's height over the ground), jumps from &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$D_a = \exp \left(\frac{-\alpha H \nu_0^2 }{(1-v_j/c_s)^2}\right)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;to &lt;/p&gt;&#xA;&#xA;&lt;p&gt;$D_r = \exp\left(\frac{-\alpha H \nu_0^2 }{(1+v_j/c_s)^2}\right)$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For typical values for the atmosphere, and the propagation of sound waves in it, this means that $D_a \ll 1$, while $D_r \approx 1$. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hence, what is happening is that, as the airplane passes roughly overhead, the sound goes from being deeply absorbed, especially at high frequencies, to not being absorbed at all (its &lt;em&gt;normal sound&lt;/em&gt;, as you call it). The strange sound you noticed is what you perceive as the lower frequencies are becoming less and less absorbed, and thus the sound spectrum changes. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 1&lt;/strong&gt;: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;after I wrote my reply, DClayton (in a comment above) gave a very important hint that this is exactly what is happening when he noticed that the same effect appears with &lt;em&gt;gliders&lt;/em&gt;, hence it is unrelated to engine sounds (I ignored this, thanks). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT 2&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;it is also worthwhile remarking what happens for high-altitude planes, when observed from the ground: in that case, the traveled distance $x$ is sufficiently large that all frequencies audible to human ears are absorbed, so that the plane goes from being nearly silent when it is approaching to being very clearly noticeable as it is receding. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may try this on a clear day with high humidity at high altitudes, when over-flying jets leave white wakes: you will be unable to hear them as they approach (even though you can see them thanks to the presence of the white wake), but you can easily hear them as they go away, but just keep in mind that all of this is delayed by the (substantial) time it takes for sound to reach the ground, which, for 33,0000 feet or more, is of order 30 seconds. In other words, you will hear the noise level grow perceptibly about 30 seconds after the jet has passed the point closest to the observer, &lt;em&gt;i.e.&lt;/em&gt; 30 seconds after flying directly overhead. &lt;/p&gt;&#xA;" OwnerUserId="14866" LastEditorUserId="14866" LastEditDate="2016-05-16T10:51:14.040" LastActivityDate="2016-05-16T10:51:14.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27466" PostTypeId="2" ParentId="27461" CreationDate="2016-05-10T11:35:53.763" Score="5" Body="&lt;p&gt;There are at least three effects that can cause this&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Doppler_effect&quot; rel=&quot;noreferrer&quot;&gt;Doppler-effect&lt;/a&gt;&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When a source of noise moves to you, you'll hear the noise with higher pitch, and when the source moves away, you'll hear it with lower pitch. This can be described by this formula, which gives the ratio of frequencies head by you and sent by the source of the noise moving with speed $v$, at speed of sound $c$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\frac{f_{heard}}{f_{send}}=\frac{1}{1-\frac{v}{c}} $$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since aircraft pass by in some distance, you can't just enter the speed of the aircraft, but this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v=\frac{v_{aircraft}\cdot x}{\sqrt{x^2+y^2}} $$&#xA;where x is the horizontal and y the vertical distance to the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I plotted this for two different speeds and several altitudes, and put the time until passing you on the x-axis:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/omYpG.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/omYpG.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shows that the total shift in frequency is larger for higher speeds and that the time the sweep takes is shorter, the nearer the aircraft passes by. BUT an airliner will not fly at 1000ft with 270kt, its more 135kt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the aircraft has to fly at really low altitude to cause a noticeable doppler effect. Here is a &lt;a href=&quot;https://www.youtube.com/watch?v=JB58g8f6lqk&quot; rel=&quot;noreferrer&quot;&gt;youtube video&lt;/a&gt; of a landing A320, recorded near the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I didn't take into account other effects like that speed of sound changes with altitude. Also Marius Matutiae meanwhile wrote something about absorption of sound in air.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Engines&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Something you can observe in that youtube video, too,  is that you can clearly hear a high, screaming noise from the fans in the beginning, which changes to a dumb rumbling from the jet blast after it passed by. &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Flaps&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Most aircraft make some noise when deploying flaps, and I would say, the &lt;a href=&quot;https://www.youtube.com/watch?v=RNZ92B7QsOA&quot; rel=&quot;noreferrer&quot;&gt;Avro RJ100 is one of the loudest airliners&lt;/a&gt; concerning this. The reverse effect can be heard when retracting the flaps, &lt;a href=&quot;https://www.youtube.com/watch?v=9F34ATDg9TU&quot; rel=&quot;noreferrer&quot;&gt;also from inside the aircraft&lt;/a&gt; (2:40)&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2016-05-10T11:35:53.763" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27468" PostTypeId="1" AcceptedAnswerId="30639" CreationDate="2016-05-10T13:30:00.660" Score="9" ViewCount="7889" Body="&lt;p&gt;This question is concerning the possibility of operating an Unmanned Aerial Vehicle (UAV) outdoors—a commercially available quadcopter, for example—but with the distinction of operating the UAV while &lt;em&gt;tethered&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In &lt;a href=&quot;https://www.ushpa.org/legacy/documents/FlightOps/FAR%20101%20vs.%20103%20-%20Legal%20Interpretation%2020150102.pdf&quot;&gt;this letter of legal interpretation&lt;/a&gt;, the FAA states, that:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The FAA has repeatedly affirmed it's position that any vehicle&#xA;  designed for tethered operations only, and not for &quot;free flight&quot;,&#xA;  should be considered a kite.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;An applicable kite (over 5 lbs., etc) would be subject to &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=b58c8e14a9b103fda47b98ca7ba8acdc&amp;amp;mc=true&amp;amp;n=pt14.2.101&amp;amp;r=PART&amp;amp;ty=HTML#se14.2.101_119&quot;&gt;14 CFR 101&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, any UAVs which were originally designed for free flight would clearly not meet the &quot;kite&quot; definition—even if operated tethered, since the original design was for &quot;free flight&quot; and not tethered operations only.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is my primary question: &lt;strong&gt;If an UAV were attached to a tether and so operated, would that UAV remain subject to all legal requirements regarding the operation of UAVs?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, I would be interested in the following:  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a letter of legal interpretation from the FAA on this matter, or any other regulatory or guidance material that I am not aware of?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any rules governing tethered &lt;em&gt;aircraft&lt;/em&gt; flight, in general, apart from &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=&amp;amp;SID=b58c8e14a9b103fda47b98ca7ba8acdc&amp;amp;mc=true&amp;amp;n=pt14.2.101&amp;amp;r=PART&amp;amp;ty=HTML#se14.2.101_119&quot;&gt;14 CFR 101&lt;/a&gt;?&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-08-10T12:43:08.087" Title="What FAA rules govern tethered, outdoor UAV flight?" Tags="&lt;faa-regulations&gt;&lt;unmanned-aerial-vehicle&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27469" PostTypeId="1" AcceptedAnswerId="27473" CreationDate="2016-05-10T15:35:49.513" Score="8" ViewCount="940" Body="&lt;p&gt;I am running some analysis on a uav, and the results I have found show that with proposed modifications I am unable to trim at my previous $c_{L\:max}$ and thus originally designed stall speed (experimentally determined).  Ideally I want to decrease my stall speed as much as possible (for obvious reasons).  Theoretically with a new flap design I can achieve higher lift coefficients however the elevator does not have enough control authority to obtain steady level flight at these conditions.  Varying my cg location somewhat will allow me to capture my original $c_{L\:max}$ but it doesn't have enough range to reach the new potential $c_{L\:max}$.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I over looking that can help me achieve a lower stall speed?  How does the propeller/power, glide slope etc effect this problem?&lt;/p&gt;&#xA;" OwnerUserId="781" LastEditorUserId="19" LastEditDate="2016-07-04T15:22:51.730" LastActivityDate="2018-07-17T06:43:05.487" Title="How do I achieve a lower stall speed, and capture potential CLmax without enough elevator control authority?" Tags="&lt;aerodynamics&gt;&lt;flight-controls&gt;&lt;stall&gt;&lt;elevator&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27470" PostTypeId="1" AcceptedAnswerId="27483" CreationDate="2016-05-10T15:53:26.493" Score="5" ViewCount="607" Body="&lt;p&gt;I have found various definitions for attitude.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.merriam-webster.com/dictionary/attitude%20of%20flight&quot; rel=&quot;nofollow&quot;&gt;Merriam Webster: &lt;/a&gt;inclination of the three principal axes of an airplane in flight to the relative wind.&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Attitude_indicator&quot; rel=&quot;nofollow&quot;&gt;Wikipedia - Attitude Indicator:&lt;/a&gt; the orientation of the aircraft relative to Earth's horizon.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;In my words, based on my current understanding:&lt;/em&gt; the angular orientation of the longitudinal and lateral axes relative to a 2D geometric plane, which is orthogonal to the Earth's average curvature at the point on the surface below the aircraft.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;What is the &lt;em&gt;correct&lt;/em&gt; reference plane for flight attitude in regards to terrestrial aerodynamic flight?&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="1696" LastEditDate="2016-06-14T16:44:14.897" LastActivityDate="2016-06-14T16:44:14.897" Title="What is the most accurate geometric plane for referencing terrestrial flight attitude?" Tags="&lt;flight-instruments&gt;&lt;terminology&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27472" PostTypeId="2" ParentId="27470" CreationDate="2016-05-10T16:03:51.703" Score="5" Body="&lt;p&gt;There are a few definitions because there are a few ways to look at it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most general thing to say would be something along the lines of, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An object's angles in pitch, roll and yaw from a set of chosen zero planes&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It boils down to what you want to use as your point(s) of reference. Attitude indicators use the horizon and if you really want to talk about it even space ships have gimbals that measure attitude relative to a plane. Your definition assumes only attitudes of aircraft flying over the earth (using the surface as a reference plane) which is valid for most cases but not all.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, attitude indicators are referenced to the horizon because it is an easy to find and generally a universal level plane with respect to the Earth's surface. In aircraft flight we care about the Earth's surface because that is where we want to get back to and subsequently not smack into in the process, so its convenient to reference to its plane. Furthermore at high altitudes the horizon is still the horizon; it simply becomes a space/Earth horizon as opposed to a sky/ground horizon. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the view out of the SR-71's cockpit (@73,000ft, this is also the highest-flying non-experimental plane ever made) to illustrate the point.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/doccZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/doccZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;http://www.extremetech.com/extreme/170463-lockheed-unveils-sr-72-hypersonic-mach-6-scramjet-spy-plane&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To extend the frame of reference explanation, we can look at the Apollo rockets &lt;a href=&quot;http://nassp.sourceforge.net/wiki/CSM_FDAI&quot; rel=&quot;nofollow noreferrer&quot;&gt;FDAI&lt;/a&gt;, which is a nice example of a 3-axis attitude indicator that was referenced to multiple planes instead of a single horizon. In this case the flight attitude was simply the angle from a chosen set of zero planes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7VISQ.gif&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7VISQ.gif&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The first one is called &quot;Inertial Stellar&quot;. That means that the reference is a 3D system of coordinates which is fix relative to the stars. That does not mean that there's only one system of reference. In fact, there is a system of reference for almost every phase of the mission. Some are reused during the flight and. in order to be accessed multiple times, they are stored in the computer as &quot;REFSMMAT&quot;, which stands for REference For Stable Member Matrix. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;-- EDIT --&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the root question has changed somewhat ill add to my answer. Generally speaking airplanes are oriented to the gravitational force below which is taken to be the &quot;vertical&quot;. The vertical is often taken to be the tangent of the ground beneath it but since the ground may also not be level this is a generalization. There is a bit of real world discussion involved here since attitude indicators, the point of reference for an aircrafts attitude may not always be perfectly level to the ground. A pilot is mainly concerned with setting his 0 degree point with a pitch that will yield flight that does not increase or decrease in altitude. This is called &quot;straight and level flight&quot;. In reality, due to the design of aircrafts this may in fact be a few degrees of pitch away from true 0 on the reference plane. Power settings will also effect this angle. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-05-10T20:51:48.890" LastActivityDate="2016-05-10T20:51:48.890" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27473" PostTypeId="2" ParentId="27469" CreationDate="2016-05-10T19:45:25.823" Score="5" Body="&lt;p&gt;It depends, partially on what you precisely mean with &quot;trim&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots use a rather narrow definition where trimming means to zero the control forces for a specific control surface deflection and speed. This is achieved by tabs or springs in the control linkage.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Engineers use it more broadly and include the ability to deflect control surfaces such that the desired attitude can be stabilized. I guess that you refer to this line of thought.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Long before the lift coefficient of a stalling airplane peaks, the flow over part of the wing will start to separate. Ideally it will do so near the trailing edge of the wing root, and the separation will slowly progress forward and outward as angle of attack increases. This separation will shift the local center of pressure back, such that the aircraft will experience an increasing nose-down moment as it approaches stall. To stabilize it at higher angles of attack will, therefore, need nonlinearly increasing elevator deflections. Depending on the position of the center of gravity, the installed elevator authority might not be sufficient to trim the aircraft all the way into the fully developed stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you mean the first interpretation of &quot;trim&quot;, then yes, most aircraft will not allow you to zero stick forces into the stationary stall. The trim range should cover the speed for steepest climb, not more. However, if the center of gravity range is wide enough, you should be able to trim an aircraft with rear c.o.g. all the way into the stall. After all, with neutral stability you can ideally trim (second interpretation) any angle of attack with the same elevator deflection angle (note that the nonlinearity explained above will require more negative elevator deflections as you approach stall even in a statically neutral aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would rule out that the control forces are too high - after all, when stalling in level flight at 1g the aircraft will fly as slowly as possible, so stick forces should be small.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effects of thrust depend on the engine installation. With a propeller, more power will add torque and increase the dynamic pressure at the tail. Now it depends whether the prop blast will hit the empennage - if it doesn't, the effect of adding power will at best be be an asymmetric stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In case you have a configuration change where the older configuration is known and the new should give the same flight characteristics, use tail volume as a sizing parameter. Horizontal tails of the same volume should give the same control power. Volume is the product of area and the lever arm between tail neutral point and the center of gravity. If the new tail has a different dihedral angle, don't forget to add the cosine of the dihedral angle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When comparing elevators of the same size but of different flap chords, use the square root of the relative flap chord for comparison. Say the old elevator has a 20% flap and the new one 30%. The new one will have 22.5% more control power for the same deflection ($\sqrt\frac{0.3}{0.2}$).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on elevator chord, at some point more deflection will not help much (typically 20° for a 25% elevator - going higher will add little control power). Now several options can be employed to increase control power:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Change the incidence of the stabilizer. That is &lt;a href=&quot;https://aviation.stackexchange.com/questions/24934/what-are-the-advantages-of-a-trimmable-horizontal-stabilizer/24938#24938&quot;&gt;what airliners do&lt;/a&gt; to compensate the massive trim changes caused by Fowler flaps.&lt;/li&gt;&#xA;&lt;li&gt;Add leading edge devices on the stabilizer to make the elevator more effective. This adds a lot of complexity for a small gain, however.&lt;/li&gt;&#xA;&lt;li&gt;Use slotted flaps and double flaps to eke more control power and higher useful deflection angles from an existing elevator. Again, &lt;a href=&quot;https://aviation.stackexchange.com/questions/24203/why-isnt-the-wing-span-of-a-certain-airliner-longer-with-the-longer-fuselage-ve/24215#24215&quot;&gt;airliners with their wing flaps&lt;/a&gt; should point the way.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In damping, both the dihedral angle and the lever arm have a quadratic influence while they have a linear influence on control power. This way one can adjust damping and control characteristics individually.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-18T21:55:55.613" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27474" PostTypeId="2" ParentId="27401" CreationDate="2016-05-10T19:50:35.710" Score="6" Body="&lt;p&gt;The Convair XC-99, cargo and passenger version of B-36 bomber, was rejected by airlines, they say, because airports were not prepared to handle over 200 passengers and their luggage disembarking at the same time, one of the main problems in the giant Airbus may be that it's close in undercarriage width to some airstrips, you remind an aircraft carrier ship deck take off and landing when watching an Airbus 380.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The type of take-off and landing of Saab Viggen, designed to eventually operate from Swedish highways, is not acceptable for commercial flights, and the marginal vortex in the tips of Airbus 380 is so powerful, that the airport must be closed for some minutes after one of these giants used it, in order to avoid an smaller airplane being send down when entering the turbulence, thus limiting the whale airplane advantage in passengers per day in this airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding huge size flying machines, you may have to look at Sci-Fi and UFO writers, eg., 'Rendezvous with Rama', or the case of a commercial flight pilot, if I remember well, going from Barcelona to Pamplona, in Spain, who watched an stationary round cloud hovering high over a dam lake, that draw his attention, and reported requesting permit from air traffic control tower to turn 360º around the cloud. He concluded the cloud wasn't a cloud, but a metallic object one and a half kilometers in size (sorry, I don't know if it was diameter or circumference), this is really much bigger than the Kalinin K-7, a heavy bomber built in 1933, that crashed for an structural failure of because a mid-air collision with a smaller airplane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who knows what the future may be in airplane size?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the end, as in the movie: 'The yellow Rolls-Royce', 'Tomorrow never comes'&lt;/p&gt;&#xA;" OwnerUserId="3424" LastActivityDate="2016-05-10T19:50:35.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27476" PostTypeId="1" CreationDate="2016-05-10T21:01:13.553" Score="5" ViewCount="10108" Body="&lt;p&gt;In &lt;a href=&quot;https://aviation.stackexchange.com/a/27473/62&quot;&gt;an answer to a previous question&lt;/a&gt;, Peter Kämpf stated:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Before the lift coefficient of a stalling airplane peaks, the flow over part of the wing will start to separate. Ideally it will do so near the trailing edge of the wing root, and the separation will slowly progress forward and outward as angle of attack increases. This separation will shift the local center of pressure back, such that the aircraft will experience an increasing nose-down moment as it approaches stall. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If separation starts at the back and progresses forward it seems to me that center of pressure ought to move forward. Why does it move back? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-05-11T05:22:39.127" Title="When approaching stall, why does the center of pressure move back?" Tags="&lt;aerodynamics&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27477" PostTypeId="2" ParentId="11272" CreationDate="2016-05-10T21:35:00.210" Score="2" Body="&lt;p&gt;From the Jeppesen glossary, &lt;a href=&quot;http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/glossary-legends.pdf&quot; rel=&quot;nofollow&quot;&gt;page 14 of this PDF&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;HIGH SPEED TAXIWAY / TURNOFF (HST)&lt;/strong&gt; — A long radius taxiway designed and provided with lighting or marking to define the path of an aircraft, traveling at high speed &lt;strong&gt;(up to 60KT)&lt;/strong&gt;, from therunway center to a point on the center of a taxiway. Also referred to as long radius exit or turnoff taxiway. The high speed taxiway is designed to expedite aircraft turning off the runway after landing, thus reducing runway occupancy time.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="14875" LastEditorUserId="1467" LastEditDate="2016-05-12T11:07:45.677" LastActivityDate="2016-05-12T11:07:45.677" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27478" PostTypeId="1" CreationDate="2016-05-10T23:12:57.123" Score="3" ViewCount="900" Body="&lt;p&gt;These are portions of two flights by a Cessna T206H on separate days:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sydae.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sydae.jpg&quot; alt=&quot;N915WC flight track&quot;&gt;&lt;/a&gt; &lt;a href=&quot;https://i.stack.imgur.com/bpj4a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/bpj4a.jpg&quot; alt=&quot;N915WC flight track&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cloverleaf portion of the track was flown at around 8200 feet altitude. This plane is typically seen over the Los Angeles basin flying &quot;lawnmower&quot; patterns similar to those that might be used for &lt;a href=&quot;http://www.dynamicaviation.com/flight-solutions-and-services/sterile-insect-technique/&quot; rel=&quot;nofollow noreferrer&quot;&gt;sterile insect technique flights&lt;/a&gt; or aerial imagery collection flights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the significance of this pattern?  Could it be for radio direction finding?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: The aircraft is N915WC, which is registered to a company that specializes in supporting the intelligence community and law enforcement.  I didn't mention that initially because I didn't want to bias people's answers, and I was curious if the pattern was distinctive enough to identify without that information.&lt;/p&gt;&#xA;" OwnerUserId="3037" LastEditorUserId="3037" LastEditDate="2016-05-11T18:21:00.170" LastActivityDate="2017-07-19T15:16:00.140" Title="What is the significance of a clover-shaped flight track?" Tags="&lt;general-aviation&gt;&lt;flight-planning&gt;" AnswerCount="2" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27480" PostTypeId="1" CreationDate="2016-05-11T01:50:34.390" Score="15" ViewCount="3673" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CfQo8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CfQo8.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pPjMl.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pPjMl.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MiG-15 and MiG-17 both have a &lt;strong&gt;split air intake&lt;/strong&gt; in their nose. However, they have &lt;strong&gt;only one jet engine&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why is the air intake split? Wouldn't it be a lot less drag to just let the intake flow cleanly into the engine?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="22726" LastEditDate="2019-09-11T23:37:36.470" LastActivityDate="2019-09-11T23:37:36.470" Title="Why do the MiG-15 and MiG-17 have a split air intake in their noses?" Tags="&lt;aircraft-design&gt;&lt;jet-engine&gt;&lt;military&gt;&lt;fighter&gt;&lt;mig-15-17&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27481" PostTypeId="2" ParentId="27476" CreationDate="2016-05-11T02:49:23.640" Score="3" Body="&lt;p&gt;The center of pressure is generally not the best way to characterize the aerodynamic forces on an aircraft since it varies with AoA.  That is why the neutral point or aerodynamic center is used instead.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Having said that the center of pressure is the location of average pressure force acting on the wing or aircraft.  Mathematically it is found by taking the sum of integral of the magnitudes of pressure and shear stress acting on the surface and multiplying it by a distance (for an airfoil from the LE) on the upper and lower surfaces resulting in a moment at the LE, or reference point.  This is then divided by the sum of the integrals of the pressure and shear stresses acting on the upper and lower surfaces.  My explanation does not do it justice see &lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/fluids/Lectures/f03.pdf&quot; rel=&quot;nofollow&quot;&gt;http://web.mit.edu/16.unified/www/FALL/fluids/Lectures/f03.pdf&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It can be somewhat complicated to calculate for an entire aircraft but in general for an airfoil it does move forward up until the point of stall or critical point after which it then moves aft.  See &lt;a href=&quot;https://www.reddit.com/r/aviation/comments/2kibfo/why_does_the_centre_of_pressure_move_rearward/&quot; rel=&quot;nofollow&quot;&gt;https://www.reddit.com/r/aviation/comments/2kibfo/why_does_the_centre_of_pressure_move_rearward/&lt;/a&gt; for a good simple explanation of this.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The movement of center of pressure is highly dependent on the configuration of the aircraft (airfoils are much simpler) and unless you are certain of the specifics of the configuration generalizing the center of pressure movement is inaccurate...&lt;/p&gt;&#xA;" OwnerUserId="781" LastActivityDate="2016-05-11T02:49:23.640" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27482" PostTypeId="2" ParentId="27476" CreationDate="2016-05-11T05:22:39.127" Score="3" Body="&lt;p&gt;It is the &lt;em&gt;overall&lt;/em&gt; centre of pressure that &lt;em&gt;includes the stabilizer&lt;/em&gt; that moves back.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is that as the flow starts to separate, the lift it generates no longer increases linearly with angle of attack. However, as long as it is properly designed, the elevator is &lt;em&gt;not stalling yet&lt;/em&gt; and its lift &lt;em&gt;does&lt;/em&gt; still increase linearly with AoA, leading to higher increase of lift on the aft surface and overall down pitch moment.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The centre of pressure of the wing itself should indeed first move forward a little as the trailing edge loses lift. Not too much, because the centre of pressure on the upside is always quite far forward to begin with. And then past $C_{L_{max}}$ it moves aft since the centre of pressure on the underside is about midchord.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-05-11T05:22:39.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27483" PostTypeId="2" ParentId="27470" CreationDate="2016-05-11T07:03:59.120" Score="3" Body="&lt;p&gt;Attitude is rotation of the body frame of reference (its principal axes, whatever it means) relative to a chosen frame of reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The body frame of reference is the longitudinal, lateral and vertical axes, where the longitudinal-vertical plane is the plane of symmetry and longitudinal axes is chosen to point generally forward, along cabin floor if there is such a thing.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The chosen outside frame of reference is the local horizontal, which is plane perpendicular to the local weight¹ vector, and in that plane the main axis is chosen either as projection of either local magnetic inductance vector (magnetic heading) or Earth rotational axis (true heading).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Regarding “true horizon”, in the sense of where the you see the ground/sky boundary, that can't be used for defining attitude at all, because it is &lt;em&gt;not a plane&lt;/em&gt;. The line connecting you to the “true horizon” ahead and the line connecting you to the “true horizon” behind is not the same line, so it can't be used as axis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Instead, horizon is defined in terms of horizontal, the plane orthogonal to the weight vector (and tangent to the Geoid, the ‘idealized’ sea level).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To fly level, your velocity vector must point along the local horizontal. In most aircraft it means your pitch is slightly positive. This is because most aircraft are designed to never need to fly at negative pitch² and as the angle of attack for level flight depends on weight and speed, most of the time your pitch will be slightly positive.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;¹ Not “gravity”, because it centrifugal force due to Earth rotation is included. Actually, the instruments measure the value including the centrifugal force due to the movement of the aircraft, which might be slightly different from centrifugal force on stationary object. The immediate measurement also includes the inertial force due to acceleration (the forces can't be distinguished), but this is eliminated by averaging, because the average acceleration (over several minutes) is known to be zero or close enough for practical purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;² There are some exceptions that do normally fly slightly nose-down, like B-52, which does it because its unusual gear does not allow it to rotate on take-off, or DHC-6 Twin Otter, which apparently does it to provide better view during slow short take-offs and landings.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-05-11T07:03:59.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27484" PostTypeId="2" ParentId="27480" CreationDate="2016-05-11T08:03:52.487" Score="13" Body="&lt;p&gt;The intake is split in order to provide a place for the squishy human pilot to sit. Sure, it would be less drag to have a straight pipe, but that would mean the pilot being subjected to the airflow. If they wanted a straight airflow they would have had to move the pilot position or move the air intake. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-05-11T08:03:52.487" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27485" PostTypeId="2" ParentId="27480" CreationDate="2016-05-11T11:51:23.727" Score="16" Body="&lt;p&gt;The advent of (turbo)jet engines resulted in an important change in design of aircraft- the location of the engine, which can either be mounted on the fuselage  or in the wings (as in Me 262).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the engine was shifted from the front (as in the case of a majority of piston engined fighters) to the rear in jet aircraft (as the exhaust has to be routed below the fuselage otherwise). In this case, the intakes can either be in the nose or in the sides (like in Hawker Hunter). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the aircraft with nose intakes (a design which was eliminated by the ever increasing size of Radar equipment), the problem was how to get the air to the engine. In case of Mig-15, the Russians split the air in a central splitter, which then passed through two narrow air ducts passing through either side of the cockpit, avionics bay, fuel tanks and the nose landing gear bay. This inlet was quite complex, not to metion it made for a cramped cockpit, but on the other had, it was compact. Similar air intakes were used in aircraft like the Mig-21.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another method was to put to simply put the cockpit above the air inlet duct, like the F-86 Sabre, which resulted in the raised stance of the cockpit (and better visibility).&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-05-11T11:58:06.583" LastActivityDate="2016-05-11T11:58:06.583" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27486" PostTypeId="1" CreationDate="2016-05-11T16:38:21.990" Score="6" ViewCount="918" Body="&lt;p&gt;Is there any FAA guidance which specifies when a call sign &amp;amp; flight number or registration number &lt;strong&gt;must&lt;/strong&gt; be used for Part 91 &amp;amp; 135 operations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am familiar with the guidance on how to obtain an ICAO call sign (and in fact work for a company who has one), but am unable to find anything which specifies when one must be used versus the other.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically, can commercial flights file under the registration number and can private flights (re-positioning flights, etc.) file under the company call sign?  I understand that this is backwards from &quot;typical&quot; use, but is it legal?&lt;/p&gt;&#xA;" OwnerUserId="69" LastEditorUserId="69" LastEditDate="2016-05-11T17:18:16.197" LastActivityDate="2016-05-14T16:46:35.650" Title="What are the FAA requirements for when to use an airline call sign &amp; flight number versus the aircraft registration number?" Tags="&lt;faa-regulations&gt;&lt;far-91&gt;&lt;aircraft-registration&gt;&lt;far-135&gt;&lt;call-sign&gt;" AnswerCount="1" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27487" PostTypeId="2" ParentId="25940" CreationDate="2016-05-11T17:32:45.857" Score="2" Body="&lt;p&gt;Related: &lt;a href=&quot;https://engineering.stackexchange.com/questions/8101/how-can-we-prove-that-thrust-to-weight-ratio-depends-by-max-speed&quot;&gt;https://engineering.stackexchange.com/questions/8101/how-can-we-prove-that-thrust-to-weight-ratio-depends-by-max-speed&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a short answer: In practice Mmax and Thrust to weight ratio are not correlated because other factors are more important, but in theory there is some dependency.  The answer depends if you're trying to compare planes, in which case you're looking at correlations among dozens of performance parameters and trying to fit estimates into simple equations.  Or you could be designing a plane, in which case you'd run equations to make sure the plane has enough thrust to meet the target Mmo. The case presented by Raymer seems to be a mix of the two.  He's using industry data to predict necessary T/W early in the design process.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Design Theory&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;The most confusing part here is that normally we think of thrust working against drag to provide acceleration, yet here we're talking about steady-state speed, not acceleration. The catch here is that drag is not constant as speed increases.  As you accelerate you reach a point where drag becomes strong enough to counteract the maximum engine thrust, and you can't go any faster in level flight (see the first graph &lt;a href=&quot;https://www.princeton.edu/~stengel/MAE331Lecture6.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;[source])&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x53xh.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x53xh.png&quot; alt=&quot;Drag versus Velocity&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assuming thrust is constant with respect to velocity, then from the formulas for drag as a function of speed we can derive  the maximum velocity.  This maximum velocity (in a thrust-limited level flight) can be written as a function of thrust-to-weight ratio and wing loading: (see derivation &lt;a href=&quot;http://www.srmuniv.ac.in/sites/default/files/downloads/class9-2012.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here (pdf)&lt;/a&gt;, compare with &lt;a href=&quot;https://www.princeton.edu/~stengel/MAE331Lecture6.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;here (pdf)&lt;/a&gt;)&#xA;$$&#xA;V_{max}=\sqrt{\frac{\frac{T_{A,max}}{W}\frac{W}{S}+\frac{W}{S}\sqrt{(\frac{T_{A,max}}{W})^2-4C_{D_{0}}K}}{\rho _{\infty }C_{D_{0}}}}&#xA;$$&#xA;Where $ T_a$ is available thrust, $W$ is the weight of the aircraft, $\frac{W}{S}$ is wing loading, $K$ is the correction factor for induced drag, and $C_{D_0}$ is the drag coefficient of aircraft when lift equals zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, you'll notice that there are other parameters in this formula besides thrust to weight ratio like wing loading and drag coefficient.  In practice these are not trivial considerations, especially when comparing different planes.  Raymer himself notes &quot;Later in the design process, aerodynamics calculation of drag at the design maximum speeds will be used, with other criteria, to establish the required T/W.&quot;  There are also factors this formula doesn't consider like the &lt;a href=&quot;http://www.grc.nasa.gov/WWW/K-12/airplane/ngnsim.html.&quot; rel=&quot;nofollow noreferrer&quot;&gt;variation in thrust as speed changes&lt;/a&gt;. These are the reasons thrust to weight ratio and maximum speed are not correlated when comparing different planes.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Comparing Planes&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Let's see if this relationship actually holds out when comparing different planes. What real-world perfomance parameter should we reference for Vmax? Mmo, high speed cruise TAS, or something else? Technically speaking, Mmo is the certified max operational speed and is a safety limit, not just a performance limit.  During descents you can pick up energy very quickly and exceed the maximum level flight speed and Mmo. However, in practice (for business jets at least) the Mmo, high speed cruise TAS, and maximum level flight speeds are correlated. After all, you don't design many planes for their diving performance and many jets are designed to cruise close to their Mmo.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The truth is that none of these speeds is closely correlated with thrust/weight when comparing jets.  In my data set of 31 business jets from &quot;Business Jets 2012&quot;, the correlation between thrust to weight and Mmo has a pitiful R-squared value of 0.20 (see the second graph). I'm not sure what data Raymer was using and if anyone has better data for showing a trend let me know.  I should note that once we account for the effects of wing-loading, there is a weak relationship between thrust to weight ratio and maximum speed.  So the effect of thrust/weight on Mmax in the above equation is very weak but present (see the third graph).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/b1tyV.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b1tyV.png&quot; alt=&quot;T/W and Mmo&quot;&gt;&lt;/a&gt;&lt;a href=&quot;https://i.stack.imgur.com/EulKm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EulKm.png&quot; alt=&quot;T/W, W/S, and Mmo&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a lot of parameters that loosely correlate with Mmo besides thrust, including aircraft type, cruise altitude, wing loading, and range.  These parameters need to be engineered in conjunction to make sure the airplane meets all the performance expectations.  Mmo may be reduced or increased so that one of these parameters reaches its target and vice versa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In theory, there is a correlation, but I have to say my stats don't agree with Raymer's on the variables being &quot;closely related&quot; when comparing different jets.  Other variables like drag and wing loading are too important to be neglected.&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="-1" LastEditDate="2017-04-13T12:51:48.340" LastActivityDate="2016-05-11T17:39:14.267" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27488" PostTypeId="1" AcceptedAnswerId="83017" CreationDate="2016-05-11T20:46:11.597" Score="11" ViewCount="1154" Body="&lt;p&gt;I was talking with a pilot about an inability to maintain the targeted climb rate in a particular situation and asked him what the Vy was for the jet.  He curtly replied &quot;Vy is only for Part 23 aircraft.&quot; (FYI for those outside the US:  Part 25 aircraft are commerical planes, while Part 23 are usually general aviation planes. You can find more details &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/airworthiness_certification/std_awcert/std_awcert_regs/regs/&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yet, I know for a fact that there is a maximum excess thrust speed, because at a certain speed drag is at a minimum. This should be close to Vy.  I also know that rate of climb is frequently listed for these aircraft. However, the optimal speed for gaining altitude isn't usually listed for commercial aircraft like it is for GA aircraft.   In fact, many of the v-speeds like Vmca and Vdec are harder to find for larger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DZDnj.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DZDnj.jpg&quot; alt=&quot;Drag vs Speed curve&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this?  I can think of several possibilities:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Commercial aircraft speeds are defined by ATC and operating procedures, not by performance considerations&lt;/li&gt;&#xA;&lt;li&gt;Commercial aircraft have enough thrust that climb performance limits isn't an issue (which I doubt from my experience).&lt;/li&gt;&#xA;&lt;li&gt;Commercial aircraft use other parameters for similar purposes like rate of climb, v2, or long range cruise speed&lt;/li&gt;&#xA;&lt;li&gt;Jets don't list this speed but propeller planes do&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="13197" LastEditDate="2016-05-11T21:40:49.820" LastActivityDate="2020-12-20T12:21:42.013" Title="Why don't Transport Category aircraft have a listed Vy?" Tags="&lt;aircraft-performance&gt;&lt;v-speeds&gt;&lt;vertical-speed&gt;&lt;far-25&gt;" AnswerCount="5" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27489" PostTypeId="1" AcceptedAnswerId="27558" CreationDate="2016-05-11T21:42:28.763" Score="7" ViewCount="1215" Body="&lt;p&gt;I have some questions regarding the stagnation points, both on an airfoil and on a generic object.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What is the physical explanation for the formation of two stagnation points on an object moving in a fluid (e.g. a cylinder)?&lt;/li&gt;&#xA;&lt;li&gt;Why in potential flow with zero circulation the rear stagnation point is located above the trailing edge of an airfoil (and not below)?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Does the Kutta condition hold even on flatback airfoils like this one? They have a truncated trailing edge, so I think the &quot;infinite velocity&quot; problem would still arise (in theory, of course).&lt;/li&gt;&#xA;&lt;li&gt;Where is the rear stagnation point located? The image below gives their approximate position, but it's not clear where the rear stagnation point is.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/o1Tvj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/o1Tvj.jpg&quot; alt=&quot;ANSYS velocity analysis of an airfoil showing stagnation points&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://upcommons.upc.edu/bitstream/handle/2099.1/14489/Report_Jose_Maria_Milian_Sanz.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="14859" LastEditorUserId="1696" LastEditDate="2016-07-06T21:43:53.023" LastActivityDate="2016-07-06T21:43:53.023" Title="What is the physical explanation for the formation and position of stagnation points on an object moving in a fluid?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27490" PostTypeId="2" ParentId="27488" CreationDate="2016-05-11T21:46:34.227" Score="14" Body="&lt;p&gt;Large commercial jets operate within a much wider range of weights than most GA aircraft do, and since Vy varies with weight, it wouldn't make sense to publish &quot;a&quot; single Vy speed for them. The crew can get a best rate or best angle of climb speed from the FMC (which &quot;knows&quot; the current weight of the aircraft, based on current fuel &amp;amp; an entered Zero Fuel Weight). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;From an empty aircraft with minimum fuel to a loaded aircraft with max fuel, the weight probably won't quite double for most commercial jet aircraft, but the one might be 170% or more of the other. With that much range, any single Vy you publish would be way far off in a lot of cases. On a GA aircraft, without an FMC and operating in a much narrower weight range, publishing a single speed makes much more sense as the delta between published and actual becomes smaller and the consequence of being a couple knots off is probably slight.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-11T21:46:34.227" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27491" PostTypeId="1" AcceptedAnswerId="27496" CreationDate="2016-05-12T01:05:40.350" Score="22" ViewCount="2473" Body="&lt;p&gt;One thing I saw on the news recently was the following image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zxAd9.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zxAd9.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How has this happened?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some details:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;British Airways A380-800.&lt;/li&gt;&#xA;&lt;li&gt;Flight BA-32 from Hong Kong to Heathrow.&lt;/li&gt;&#xA;&lt;li&gt;While climbing out of Hong Kong crew received a tyre pressure notification, but continued on as the A380 can land with 1 of it's 18 tyres flat. &lt;/li&gt;&#xA;&lt;li&gt;Landed safely, but had to request a tug to the gate.&lt;/li&gt;&#xA;&lt;li&gt;The photo above is after landing.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I can't seem to find a clear explanation to why the tyre has gone this square shape. Generally when a tyre is flat it's round with the bottom being straight. The explanations seem to vary between tyre pressure, to the way it lands, to the way it is stored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's the real reason it's square?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://avherald.com/h?article=498050d8&quot; rel=&quot;noreferrer&quot;&gt;http://avherald.com/h?article=498050d8&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8300" LastEditorUserId="8300" LastEditDate="2016-05-12T08:57:43.597" LastActivityDate="2016-05-12T10:26:24.787" Title="Why Is This Tyre Square On The BA A380?" Tags="&lt;airbus-a380&gt;" AnswerCount="1" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="27493" PostTypeId="2" ParentId="8403" CreationDate="2016-05-12T03:15:14.563" Score="0" Body="&lt;p&gt;They could get to their target if they pressurised the cabin, chose a turbo charged engine, and flew at FL25. Current max cruise speed is achieved at FL12.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, if they went with the IO540 with 350hp they could have the record for fastest piston single, I estimate 262KTAS at FL25. Probably worried about heat dissipation. Also, it isn't what they want to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SMA 400hp diesel would be interesting in this plane, despite weighing 600lbs. &lt;/p&gt;&#xA;" OwnerUserId="14885" LastActivityDate="2016-05-12T03:15:14.563" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27494" PostTypeId="1" CreationDate="2016-05-12T08:22:22.827" Score="4" ViewCount="1365" Body="&lt;p&gt;I am developing C# code that reads 1090ES Automatic Dependent Surveillance - Broadcast  (ADS-B). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ADS-B position messages broadcast by the aircraft's ADS-B transmitter have a different encoding depending on whether the aircraft is airborne or on the ground. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I decode Airborne Position frames as Compact Position Reporting (CPR) encoded positions, I get realistic results. However, when I decode the CPR for Surface Position frames, the positions I get are far (geographically) from what I should get.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How is the CPR in Surface position messages different from airborne position messages and how are they decoded properly?&lt;/p&gt;&#xA;" OwnerUserId="13099" LastEditorUserId="19" LastEditDate="2016-10-14T13:39:40.627" LastActivityDate="2016-10-14T13:39:40.627" Title="How are ADS-B surface position frames decoded?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27495" PostTypeId="1" CreationDate="2016-05-12T10:24:06.593" Score="2" ViewCount="226" Body="&lt;p&gt;Among the currently certified &lt;a href=&quot;https://www.easa.europa.eu/system/files/dfu/agency-measures-docs-certification-specifications-CS-23-CS-23-Amdt-3.pdf&quot; rel=&quot;nofollow&quot;&gt;CS-23 airplanes&lt;/a&gt; (or &quot;Part 23&quot; in FAA-land or your personal region equivalent), which has the lowest rotation speed ($V_r$)?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="946" LastEditDate="2016-06-14T07:53:02.347" LastActivityDate="2016-06-14T07:53:02.347" Title="Which CS-23 airplane has the lowest takeoff speed?" Tags="&lt;aircraft-performance&gt;&lt;takeoff&gt;&lt;cs-23&gt;" AnswerCount="0" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27496" PostTypeId="2" ParentId="27491" CreationDate="2016-05-12T10:26:24.787" Score="27" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.fzt.haw-hamburg.de/pers/Scholz/dglr/hh/text_2008_06_05_LandingGear.pdf&quot;&gt;this document&lt;/a&gt; about the landing gear system, the wheel dimension  of the main lading gears is 1400x530 R23. This is not the standard notation known from car tires, but it says that the diameter is 1400mm and the width is 530mm, so the tread has a surface of about 2,3m².&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The same document further states:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Depending on the flight phase, a warning will be triggered if a &#xA;  tyre pressure is detected below a given percentage of the nominal tyre pressure (for 5 seconds continuously).&lt;br&gt;&#xA;  Likewise, a warning will be triggered if a differential pressure above a given percentage is detected across tyres on the same axle (measured from the tyre with the higher pressure). &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;though no concrete threshold is given.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nominal pressure of the tires is 15Bar (atm) and will quickly fall, even when there's just a tiny leak. So no wonder there was a warning during climb.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During the 13h flight at up to 40.000ft, the pressure could easily fall to the environmental pressure of about 0.2Bar at that altitude. And from that altitude, it takes only 30min to landing (taken from flightaware for a BA32 flight), which may not be enough to equalize tire pressure to ambient pressure through a tiny leak. Also, ambient pressure will rise slowly in the beginning and reach 1Bar at ground quite late.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the pressure in the tire was still 0.2Bar when landing, the pressure difference to the ambient caused a force of 176kN on the tread, which equals a weight of 18t or 39700lbs! (one could also say: 4.5t or 5000lbs on each of the sides of this square shaped tire.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So it's no wonder that the tire was compressed, though this doesn't explain why the tire choose the square shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, the tire tries to minimize its volume while the surface is constant, but it can't change to any shape. Its stiffness and the rim only allow the tread to bulge inwards. From math, we know that the more sides a symmetric polygon has, the more surface it has w.r.t its circumference. So the less sides, the better.  A triangular shape seems not to be possible due to the rim and the needed large force to bend side walls. A pentagon doesn't provide enough reduction of volume, so a square is the best choice.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So though the picture looks really crazy, the square shape is not that surprising.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a tire does not think about how to collapse best to minimize volume. It starts an one or more points and evolves. If it starts with three bulges, it could have stayed with it, and the A380 had landed with a triangular tire. May be, a fourth bulge has developed at some point. Maybe, the shape in air was different, and some punched during landing pushed the tire into that shape. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, one can only say that it's clear that the tire collapses to something like this due to the ambient pressure working against the low pressure inside, but one can not really predict the resulting shape. But the rectangular shape seems to be the best to minimize volume.&lt;/p&gt;&#xA;" OwnerUserId="4170" LastActivityDate="2016-05-12T10:26:24.787" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27498" PostTypeId="1" AcceptedAnswerId="32448" CreationDate="2016-05-12T14:08:51.183" Score="3" ViewCount="958" Body="&lt;p&gt;I am considering obtaining an EASA PPL in the U.K. I would like to know where exactly in the world the license is recognized with little to no additional paperwork/training outside of Europe. Specifically I would like to know what is needed to fly in the Caribbean, Colombia or Chile with this license.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am a complete aviation beginner so apologies if this is a silly question.&lt;/p&gt;&#xA;" OwnerUserId="14888" LastActivityDate="2016-10-17T14:13:10.703" Title="Where is an EASA PPL valid outside of Europe?" Tags="&lt;ppl&gt;&lt;easa&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27500" PostTypeId="1" AcceptedAnswerId="27508" CreationDate="2016-05-12T15:33:28.470" Score="11" ViewCount="1619" Body="&lt;p&gt;In these two lovely images:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/6/60/J58_AfterburnerT.jpeg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/commons/6/60/J58_AfterburnerT.jpeg&quot; alt=&quot;https://upload.wikimedia.org/wikipedia/commons/6/60/J58_AfterburnerT.jpeg&quot; /&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/File%3AJ58_AfterburnerT.jpeg&quot; rel=&quot;noreferrer&quot;&gt;Wikimedia Commons&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/GY4Ds.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/GY4Ds.jpg&quot; alt=&quot;http://www.wvi.com/~sr71webmaster/J58AB.jpg&quot; /&gt;&lt;/a&gt;&lt;br&gt;&lt;sup&gt;Source: &lt;a href=&quot;http://www.wvi.com/%7Esr71webmaster/j-58%7E1.htm&quot; rel=&quot;noreferrer&quot;&gt;wvi.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The exhaust end of the engines are glowing bright orange from being so hot. Do they get that hot during normal flight operations, or are they hot because the engines are statically mounted for testing and have (relatively) minimal air flow to cool it?&lt;/p&gt;&#xA;&lt;p&gt;If it's normally this hot, what is the exhaust made of, and how is it insulated to keep it from melting the nacelle around it?&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2020-02-12T04:01:59.427" Title="Do jet engine exhausts usually glow orange?" Tags="&lt;jet-engine&gt;&lt;temperature&gt;" AnswerCount="3" CommentCount="10" ContentLicense="CC BY-SA 4.0" />
  <row Id="27501" PostTypeId="2" ParentId="27494" CreationDate="2016-05-12T17:42:01.890" Score="4" Body="&lt;p&gt;The Compact Position Report (CPR) coding in Surface squiters is different from Airborne CPR coding. The resolution is 4 times better (~1.25 m instead of ~ 5 m), at the cost of losing the 2 most significant bits. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, global surface position decoding gives an ambiguous solution. IIRC the solution can be at 4 points on the globe, you have to select the nearest to you. And you should validate that it is within a realistic range, like you should do with Airborne CPR decoding. After you validated the position using global decoding on a couple of odd- even squiter pairs you can use the more efficient local decoding. Of course, as with Airborne CPR decoding, you need to protect against position jumps and time gaps in your decoding algorithm. &lt;/p&gt;&#xA;" OwnerUserId="19" LastActivityDate="2016-05-12T17:42:01.890" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27502" PostTypeId="1" CreationDate="2016-05-12T17:55:08.870" Score="6" ViewCount="3866" Body="&lt;p&gt;I know that other countries like Brazil, Argentina, etc. do publish minimum and maximum temperatures in their Terminal Aerodrome Forecasts, abbreviated TN and TX. But why are they not shown in TAFs in the United States? (I guess other countries in Europe also have the temperatures).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BTW, where are the expected min and max temperatures in the US published in an official report? NOAA/NWS? WX-BRIEF?&lt;/p&gt;&#xA;" OwnerUserId="14891" LastEditorUserId="62" LastEditDate="2016-05-12T18:46:46.823" LastActivityDate="2016-05-12T18:46:46.823" Title="Why are min and max temperatures (TN TX) not published in TAFs in the United States?" Tags="&lt;weather&gt;&lt;usa&gt;&lt;temperature&gt;&lt;taf&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27503" PostTypeId="1" AcceptedAnswerId="27504" CreationDate="2016-05-12T18:00:49.063" Score="18" ViewCount="9321" Body="&lt;p&gt;I had always been under the impression that the forces of air rushing out a broken window or hole in an airplane would be pretty limited and nothing near the levels necessary to carry a body through to the outside. The scene in &lt;em&gt;Goldfinger&lt;/em&gt; has always been scoffed at by other pilots I have known.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, recently I discovered that allegedly &lt;a href=&quot;http://home.bt.com/news/world-news/june-10-1990-miracle-of-ba-flight-5390-as-captain-is-sucked-out-of-the-cockpit-and-survives-11363985642960&quot; rel=&quot;noreferrer&quot;&gt;the pilot of an airliner was sucked out of a cockpit window&lt;/a&gt; in 1990 (re-enactment photo below):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TYerZ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TYerZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seems fishy to me. Is this for real? Can you really be sucked out of an aircraft window? Remind me to buckle up. Gives a whole new meaning to the word &quot;deplaning&quot;.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2020-01-18T23:54:41.547" Title="Can you get sucked out of a hole in an aircraft?" Tags="&lt;cabin-pressure&gt;" AnswerCount="2" CommentCount="9" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27504" PostTypeId="2" ParentId="27503" CreationDate="2016-05-12T18:22:41.410" Score="34" Body="&lt;p&gt;Yes, it's real. Here's the &lt;a href=&quot;https://assets.digital.cabinet-office.gov.uk/media/5422faa7e5274a131400078d/1-1992_G-BJRT_2_.pdf&quot;&gt;official accident report&lt;/a&gt; on BA5390, which says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The commander had been partially sucked out of his windscreen aperture&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The two men tried to pull the commander back within the aircraft [but]&#xA;  the effect of the slipstream frustrated their efforts&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There's also &lt;a href=&quot;https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243&quot;&gt;Aloha 243&lt;/a&gt; where one cabin crew member was ejected, although that was a really extreme case.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-12T18:22:41.410" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27505" PostTypeId="2" ParentId="27502" CreationDate="2016-05-12T18:42:56.007" Score="5" Body="&lt;p&gt;This isn't much of an explanation, but &lt;a href=&quot;https://www.aviationweather.gov/static/help/taf-decode.php&quot; rel=&quot;noreferrer&quot;&gt;the National Weather Service says&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The international TAF also contains forecast temperature, icing, and&#xA;  turbulence. These three elements are not included in National Weather&#xA;  Service (NWS) prepared TAFs. The U.S. has no requirement to forecast&#xA;  temperatures in an aerodrome forecast&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That sounds to me like &quot;we don't think it's worth it&quot;. There are various temperature forecasts on the NWS aviation site (&lt;a href=&quot;https://www.aviationweather.gov/icing/frzlvl&quot; rel=&quot;noreferrer&quot;&gt;icing level&lt;/a&gt;, &lt;a href=&quot;https://www.aviationweather.gov/windtemp/plot&quot; rel=&quot;noreferrer&quot;&gt;surface temperatures&lt;/a&gt;, &lt;a href=&quot;http://new.aviationweather.gov/areafcst&quot; rel=&quot;noreferrer&quot;&gt;graphical area forecast&lt;/a&gt;) but personally speaking, I get low/high temperature information from regular, non-aviation forecasts. You can get those forecasts from &lt;a href=&quot;http://forecast.weather.gov/MapClick.php?lat=38.22221656694211&amp;amp;lon=-85.68080179316746#.VzTN7YQwgdU&quot; rel=&quot;noreferrer&quot;&gt;the NWS site&lt;/a&gt; too, if that's what you mean by &quot;official&quot;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-12T18:42:56.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27506" PostTypeId="1" AcceptedAnswerId="27511" CreationDate="2016-05-12T19:23:35.717" Score="11" ViewCount="2718" Body="&lt;p&gt;I am part of a team developing a Cessna 172 P model for FlightGear, an open source free flight simulator. We are now programming how the panel and radio lightning rheostat should work, but we found a lot of unclear and/or contradictory information about it online. Our main problem is to understand how the radio light knob (labelled as RADIO LT) work in these older models of the 172.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The POH from 1982 states the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The engine instrument cluster (if post lights are installed), radio equipment, and magnetic compass have integral lightning and operate independently of post or flood lightning. The intensity of this lightning is controlled by the inner knob on the light dimming rheostat labelled RADIO LT; rotate the knob clockwise to obtain the desired light intensity. However, for daylight operation, the compass and engine instrument lights may be turned off while still maintaining maximum light intensity for the digital readouts in the radio equipment. This is accomplished by rotating the RADIO LT knob full counterclockwise. Check that the flood lights/post lights are turned off for daylight operation by rotating the PANEL LT knob full counterclockwise.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This makes it look like the RADIO LT knob controls both the brightness of the radio digital readouts (i.e. the frequency digits) as well as other types of lights (radio cluster buttons and compass), but I found out that other renowned simulations of the 172 for other simulators do not dim the digital readouts with that knob. It also seems strange to me that one would be able to dim the radio digits under any condition, let alone turn them completely off.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So does anyone here have experience with these models of the 172? Would anyone be able to describe how to best model the behaviour of the radio lights?&lt;/p&gt;&#xA;" OwnerUserId="399" LastEditorUserId="1696" LastEditDate="2016-05-12T19:49:12.950" LastActivityDate="2016-06-24T20:08:28.247" Title="What lights does the Cessna 172 light rheostat control?" Tags="&lt;cockpit&gt;&lt;electrical-system&gt;&lt;cessna-172&gt;&lt;aircraft-lighting&gt;" AnswerCount="3" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27507" PostTypeId="2" ParentId="25746" CreationDate="2016-05-12T19:50:13.653" Score="0" Body="&lt;p&gt;Aircraft do not need to be pressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above about 12,000 feet humans need additional oxygen.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above about 50,000 feet any humans inside the aircraft need to be wearing pressure suits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no &quot;requirement&quot; for any aircraft to be pressurized.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-12T19:50:13.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27508" PostTypeId="2" ParentId="27500" CreationDate="2016-05-12T20:02:32.470" Score="11" Body="&lt;p&gt;Both images you posted are of &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J58&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pratt&amp;amp;Whitney J58&lt;/a&gt; &lt;a href=&quot;https://en.wikipedia.org/wiki/Afterburner&quot; rel=&quot;nofollow noreferrer&quot;&gt;afterburning&lt;/a&gt; turbojet that was used on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_A-12&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed A-12&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_SR-71_Blackbird&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed SR-71&lt;/a&gt; aircraft. That engine ran particularly hot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine was designed for operation at Mach 3.2. The efficiency of turbojet increases with speed, but only to a certain point and somewhere above Mach 2 it starts to decline. However efficiency of afterburner continues to increase, so this engine was designed to operate continuously with afterburner and to generate higher fraction of power in the afterburner than other engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The afterburner combustor liner was able to withstand temperature up to 1,760°C (3,800°F). The core of the flame was much hotter still, but a colder air was fed along the walls, like in all turbine engines, as explained &lt;a href=&quot;https://aviation.stackexchange.com/q/16841/524&quot;&gt;here&lt;/a&gt;. The engine was also cooled by incoming fuel similarly to how rocket engines are.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Additionally, at the top speed, the compression heating as the air was slowed to subsonic speed in the inlet heated it to over 400°C (800°F) at the compressor face already. Since in the static test the air was not that hot, the engine might have actually ran a bit &lt;em&gt;colder&lt;/em&gt; in the test than in normal operation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was however specific to this one engine. The compression heating is negligible at subsonic speeds and grows faster at higher Mach numbers. Most supersonic aircraft fly around Mach 2, where the effect is already noticeable, but not nearly as pronounced. For most engines, they run at roughly the same temperature in test as they do in normal operation. It just isn't as high as in this special case.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-05-12T20:02:32.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27509" PostTypeId="1" CreationDate="2016-05-12T20:32:13.063" Score="4" ViewCount="1672" Body="&lt;p&gt;I'm looking to do a N1 low idle speed adjustment oa King Air B350 with the PT6A-60A engine. There is a note saying that one flat movement of the low idle speed screw in the FCU increases N1 by 3.5%&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is &quot;one flat movement&quot; in this context?&lt;/p&gt;&#xA;" OwnerUserId="14893" LastEditorUserId="5517" LastEditDate="2016-05-13T14:07:47.723" LastActivityDate="2016-05-13T14:07:47.723" Title="What is &quot;one flat movement&quot; of a screw on the fuel control unit?" Tags="&lt;aircraft-maintenance&gt;" AnswerCount="0" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27510" PostTypeId="1" CreationDate="2016-05-12T22:32:12.817" Score="13" ViewCount="1683" Body="&lt;p&gt;Wikipedia article on &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15&quot;&gt;MiG-15&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Another major design deficit was that the tank could develop under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, destroying the aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-17&quot;&gt;MiG-17&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Like its forebear, the MiG-17 inherited the major design deficit which could cause the fuel tanks develop to under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, crushing the main fuselage of the aircraft mid-fight, with almost always fatal results.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19&quot;&gt;MiG-19&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Initial enthusiasm for the aircraft was dampened by several problems, the most alarming inherited from MiG-15/MiG-17 was the danger of mid-air tank implosions when more than half of the fuel had been used - the leaking fuel of the crushed fuselage fuel tanks located between the engines would then ignite, leading to a fatal explosion;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-21&quot;&gt;MiG-21&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Additionally when more than half the fuel was used up, violent maneuveurs prevented fuel from flowing into the engine, thereby causing it to shutdown midflight.&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19&quot;&gt;3&lt;/a&gt; and risking tank implosions (a problem inherited from MiG-15/MiG-17 and MiG-19).&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;None of these entries has a citation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would like to know if these aircraft really did have a design flaw in the fuel tanks, and if so, &lt;strong&gt;what was it?&lt;/strong&gt; What was wrong with the tank that made it susceptible to implosions once more than 50% of fuel was gone?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="22726" LastEditDate="2019-09-12T21:03:16.650" LastActivityDate="2019-09-12T21:03:16.650" Title="Was there a design flaw in the fuel tanks of the MiG-15/17/19/21?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;fighter&gt;&lt;fuel-tanks&gt;&lt;mig-15-17&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27511" PostTypeId="2" ParentId="27506" CreationDate="2016-05-12T22:47:27.293" Score="4" Body="&lt;p&gt;This depends more on the radios installed than the plane its self, older era planes may have had King radios with analog numeric readouts. These radios are generally back lit and controlled by what ever rheostat controls the panel those radios generally look like this &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qPuOM.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qPuOM.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://i.ebayimg.com/00/s/Mzc1WDUwMA==/z/CnoAAOxycmBS-qrg/$_35.JPG?set_id=2&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;later planes may have had digital readouts which in some cases had another control to dim the intensity. This is often because in a sense the lights are always on you may need to control them with out turning on or dimming the panel. As a matter of fact you generally want them to work opposite, during the day when the panel is dim or off you want the radio lights to be brightest they would then be dimmed in the evening as you bring the panel lights on. Those radios often looked like this, &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MSDkv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MSDkv.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://thumbs.ebaystatic.com/images/g/DZkAAOSwLmVXEBMX/s-l225.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The dim function may appear on units like the DME and Auto Pilot if they are similarly lit. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its been a while since I have night flown with one but if memory servers the newer GPS units like the GNS430/540 have backlit buttons that come on when the panel lights are activated. These units also tend to have separate ways to control the screen brightness/contrast&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/X9L1B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/X9L1B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://www.gulfcoastavionics.com/images/products/3214/gns-530.jpeg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may have more luck referencing the manuals for the radios them selves than the POH for the plane. You should design for the types of radios you are putting in (looks wise)  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-05-13T14:32:54.167" LastActivityDate="2016-05-13T14:32:54.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27512" PostTypeId="2" ParentId="27510" CreationDate="2016-05-12T23:59:48.513" Score="9" Body="&lt;p&gt;I found a reference to exploding fuel tanks on Mig-21's caused by overheating engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.airvectors.net/avmig15_3.html&quot;&gt; &quot;it had an unfortunate tendency to explode in mid-air. The problem was finally traced to a fuel tank placed under the engines that could cook up when the engines overheated.&quot;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;em&gt;Like its forebear, the MiG-17 inherited the major design deficit which&#xA;  could cause the fuel tanks develop to under-pressure if more than half&#xA;  the fuel had been used, which could easily lead to tank implosions,&#xA;  crushing the main fuselage of the aircraft mid-fight, with almost&#xA;  always fatal results.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Tank implosion implies negative tank pressure. Under pressure or negative pressure is caused by improper fuel tank venting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;High pressure pumps sucking fuel out of an improperly vented tank can quickly develop negative pressure which can cause a tank collapse. If the tank was integral to the fuselage it could also cause an airframe failure. A collapsed tank could also leak fuel which could lead to catastrophic failure if the fuel found an ignition source. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-05-13T00:05:02.047" LastActivityDate="2016-05-13T00:05:02.047" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27513" PostTypeId="1" AcceptedAnswerId="27514" CreationDate="2016-05-13T08:13:51.373" Score="0" ViewCount="1309" Body="&lt;p&gt;I'm trying to &quot;compile&quot; single list of IATA meal codes. By using different airlines and data sources I have found many meal codes. However, I have also found problems with codes that are used to mean different things, or different codes used to mean the same thing. For example:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;On &lt;a href=&quot;http://www.cathaypacific.com/cx/en_HK/travel-information/inflight/food-and-beverages/special-meals.html&quot; rel=&quot;nofollow&quot;&gt;Cathay Pacific's special meal page&lt;/a&gt; I have found an information, that both &lt;code&gt;Non-Beef Meal&lt;/code&gt; and &lt;code&gt;Liquid Diet Meal&lt;/code&gt; are using the same code of &lt;code&gt;SPML&lt;/code&gt;. These meal types seems to be far different. How to understand this? A bug on CP's page? To make things more complicated, another source uses &lt;code&gt;SPML&lt;/code&gt; code for &lt;code&gt;Special Meal or Specify Meal&lt;/code&gt;.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Cathay Pacific uses &lt;code&gt;VGML&lt;/code&gt; for &lt;code&gt;Vegetarian Vegan Meal&lt;/code&gt; (&lt;em&gt;Strict vegetarian food with high protein, rich iron and high calcium&lt;/em&gt;). Other source uses &lt;code&gt;VVML&lt;/code&gt; code for this meal type and have &lt;code&gt;VGML&lt;/code&gt; code reserved for &lt;code&gt;Vegetarian Non-Dairy Meal&lt;/code&gt;. Is there any difference between these two meal types and if yes, then which code is correct / official according to IATA.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Help with the above two examples would be appreciated. However, my main question is:&lt;br&gt;&#xA;&lt;strong&gt;Where can I find official IATA codes for food?&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is any &quot;ultimate source&quot;, that we can / should use for this purpose (ignoring airline's specific listings, as in case of Cathay Pacific)? If so, then please, provide a link to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: &lt;em&gt;Please, consider above paragraph. This question asks official IATA meal list, not about airline-specific regulations.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="3230" LastEditDate="2016-05-16T07:16:16.593" LastActivityDate="2021-03-27T16:54:18.437" Title="Where can I find an accurate list of IATA meal codes?" Tags="&lt;airline-operations&gt;&lt;iata&gt;" AnswerCount="1" CommentCount="7" ClosedDate="2016-05-16T22:49:56.013" ContentLicense="CC BY-SA 3.0" />
  <row Id="27514" PostTypeId="2" ParentId="27513" CreationDate="2016-05-13T08:21:52.007" Score="3" Body="&lt;p&gt;SPML is Special Meal, differs from airline to airline.&lt;/p&gt;&#xA;&lt;p&gt;VGML is vegan, i.e. not even dairy products are used. Unlike vegetarian were animal products can be used, say eggs or milk.&lt;/p&gt;&#xA;&lt;p&gt;Source: International Air Transport Association. &amp;quot;&lt;a href=&quot;https://www.skybrary.aero/bookshelf/books/3996.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Cabin Operations Safety Best Practices Guide&lt;/a&gt;.&amp;quot; (2017).&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2021-03-27T16:54:18.437" LastActivityDate="2021-03-27T16:54:18.437" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27515" PostTypeId="1" CreationDate="2016-05-13T09:24:33.993" Score="6" ViewCount="3648" Body="&lt;p&gt;Right now at my university we are busy with a project for designing a conceptual aircraft. Our aircraft is in the CS-23 range, this airplane is a small cargo aircraft with the option for carrying injured passengers (so like an ambulance aircraft).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our aircraft will have a cruise height at 10,000 ft. We want to make this aircraft pressurised but our question is therefore, is it possible to pressurise the aircraft from inside below the normal 8,000ft. So for example, we are flying at 10,000 ft but we want to have the inside pressure having the same as on sea level if that is possible, or is it only possible to pressurise the inside at 8000ft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thank you in advance.&lt;/p&gt;&#xA;" OwnerUserId="14898" LastEditorUserId="770" LastEditDate="2016-05-14T06:19:56.730" LastActivityDate="2021-02-21T21:14:12.943" Title="Can an aircraft at 10,000 feet have sea level pressure in the cabin?" Tags="&lt;aircraft-design&gt;&lt;cs-23&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27516" PostTypeId="2" ParentId="27515" CreationDate="2016-05-13T09:40:30.953" Score="9" Body="&lt;p&gt;The &lt;a href=&quot;http://www.syberjet.com/&quot; rel=&quot;nofollow&quot;&gt;SyberJet SJ30&lt;/a&gt; business jet flies way higher, around FL410, and it is pressurized at sea-level. Composite materials help in coping with extreme cycles.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-06-21T21:16:27.570" LastActivityDate="2016-06-21T21:16:27.570" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27517" PostTypeId="2" ParentId="27515" CreationDate="2016-05-13T09:41:38.570" Score="22" Body="&lt;p&gt;If you design the aircraft, shouldn't you be answering that question? If it is part of your aircraft's mission to fly at 10.000ft whilst maintaining sea level cabin pressure, then you should design it that way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why would it only be possible to pressurize the inside to 8000ft? Not to 9000ft, 7000 ft or any other arbitrary altitude?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course the construction of the aircraft needs to be able to withstand the forces caused by pressure difference between the inside of the cabin and the outside. And the pressurization system needs to be able to maintain the pressure at sea level, so compensating for any air leaks in the pressure vessel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For an initial feasibility study you could look at the pressure difference on the hull when an aircraft is flying at FL430 whilst maintaining cabin pressure at 8.000ft. Note thate the Boeing 787 maintains the cabin altitude at &lt;a href=&quot;https://aviation.stackexchange.com/q/1728/19&quot;&gt;6.000ft, while operating at 43.000 ft&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Compare that to the pressure difference between 10.000ft and sea level. &#xA;Looking at those pressure differences should give you a feeling whether or not it is easy to achieve your objective.  &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-13T09:41:38.570" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27520" PostTypeId="2" ParentId="26771" CreationDate="2016-05-13T21:18:43.703" Score="2" Body="&lt;p&gt;The answer is &quot;yes&quot; if &lt;/p&gt;&#xA;&#xA;&lt;p&gt;a) you configure your 1090 out system to request ADS-B uplink at 978 MHZ (this feature was added to the message structure in DO-260B)&#xA;b) your 1090 ADS-B out message is confirming certain minimum &quot;quality&quot; standards related to both the quality of the position information (GPS Integrity or &quot;NIC&quot;) and the quality of the avionics (SDA or system design assurance)and the quality of the install or SIL  The specifics of what quality message triggers the system is under review by the FAA, but if you equipment is certified (TSO'd) and the install is in accordance with AC-20/165B you will be fine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, if you have a UAT ADS-B you can specify which uplink frequency you want in the same way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further note - almost all ADS-B system are single band transmitters (ADS-B Out) and dual band receivers (ADS-B In). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nuance - the uplink is broadcast to the quadrant (relative to the ground station) where you are flying.  This can lead to aircraft with no or &quot;below quality&quot; ADS-B out receiving traffic intended for another aircraft.  Depending on geometry this can create a partial traffic picture which can be quite misleading and potentially dangerous&lt;/p&gt;&#xA;" OwnerUserId="14904" LastActivityDate="2016-05-13T21:18:43.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27521" PostTypeId="1" CreationDate="2016-05-13T21:42:37.653" Score="21" ViewCount="5996" Body="&lt;p&gt;In another question, someone said everyone but Mooney has the vertical stabilizer on backward. (As a Cessna driver, this looks backwards to me). Is there an aerodynamic reason or some reason other than marketing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Note the slants of the leading and trailing edges.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wxBP8.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wxBP8.jpg&quot; alt=&quot;Mooney M20&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/G1vSC.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/G1vSC.jpg&quot; alt=&quot;Cessna 182&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="132" LastEditorUserId="62" LastEditDate="2016-05-14T13:55:53.353" LastActivityDate="2020-06-24T23:46:24.600" Title="Why is the Mooney's signature tail profile different from most planes?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;" AnswerCount="5" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27522" PostTypeId="1" AcceptedAnswerId="27538" CreationDate="2016-05-14T00:22:12.370" Score="7" ViewCount="476" Body="&lt;p&gt;Say you have an eastbound flight at FL210 that wants to climb and a westbound flight on a converging track at FL220 that wants to descend. There's the minimum required 1000 ft vertical separation. Once the planes have passed each other can ATC clear them to climb/descend right away or do they have to wait until they are 5nm apart before they can break the vertical separation? And what about TCAS? Would it consider that a conflict? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-07-09T20:29:05.250" Title="Does ATC have to maintain separation on diverging aircraft?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;separation&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27523" PostTypeId="2" ParentId="27252" CreationDate="2016-05-14T00:26:38.893" Score="5" Body="&lt;p&gt;Well in air you don't have to worry about &lt;a href=&quot;https://www.youtube.com/watch?v=vkvJJMmRjHk&quot; rel=&quot;nofollow noreferrer&quot;&gt;kangaroos in your path&lt;/a&gt; or &lt;a href=&quot;https://en.wikipedia.org/wiki/Dash_8_landing_gear_incidents#Similar_incidents_with_Dash_8s&quot; rel=&quot;nofollow noreferrer&quot;&gt;a wheel falling off unnoticed&lt;/a&gt;, or &lt;a href=&quot;http://www.asias.faa.gov/pls/apex/f?p=100:18:0::NO::AP_BRIEF_RPT_VAR:20151106017929I&quot; rel=&quot;nofollow noreferrer&quot;&gt;people beside a taxiway mistakenly indicating you won't hit a golf cart&lt;/a&gt;.  Heaven forbid &lt;a href=&quot;https://aviation.stackexchange.com/questions/26279/can-the-landing-gear-be-pulled-up-while-the-plane-is-on-the-ground&quot;&gt;you accidentally retract the landing gear&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Jokes aisde, taxiing can be a major challenge even for experienced pilots. First off, your traditional warning systems don't work.  You can't check your route using a low or mid-range GPS because they don't have airport taxiway information.  You won't get a &quot;terrain!&quot; warning when you're about to head off the end of a taxiway. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Steering is difficult because the control surfaces are used differently on the ground, especially in a crosswind.  You don't use your ailerons or elevator to control your path; you use them to keep the wings from lifting and to keep you on the ground.  You use the rudder and steerable nose wheel/tail-wheel (if present) to keep you on the right path, with help from the brakes only when necessary.   Those brakes definitely will be necessary in a tail-wheel aircraft with a strong enough crosswind.  If you fail to control the ground path in a tail-wheel aircraft, an unstable and difficult &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/2013/january/17/dont-let-the-ground-loop-get-you&quot; rel=&quot;nofollow noreferrer&quot;&gt;ground loop&lt;/a&gt; can develop. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Did wbeard52 mention low visibility? You can technically land a plane in zero visibility if your plane and the airport are properly equipped, but good luck naviagting the taxiways afterwards. A pilot once remarked that &quot;Taxiing at ORD the first time in low visibility conditions is impossible,&quot; and another remarked that he was so confused by low visibility he had to have a follow-me truck guide him. &lt;a href=&quot;http://www.iasa.com.au/folders/Safety_Issues/FAA_Inaction/callfortaxi.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;[source]&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taxiing can also be confusing in good weather, especially at night.  Sometimes the taxiway letters jump randomly around the alphabet, sometimes markings are obstructed, sometimes there's construction (you don't see construction much in the air!).   The FAA has an entire handbook &lt;a href=&quot;https://www.faa.gov/airports/runway_safety/media/pdf/PHAK%20-%20Appendix%201%20-%20April%202012.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;appendix&lt;/a&gt; devoted to avoiding runway incursions that explains these navigational issues.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also have to be vigilant for obstacles around you (like those kangaroos I mentioned earlier).  In a tail-wheel aircraft with a high nose, for example, it's recommended to zig-zag a little so you can see what's right in front of you.   In aircraft like the B777-300 they actually have camera systems to augment visibility.  (see &lt;a href=&quot;https://aviation.stackexchange.com/questions/7849/how-do-pilots-manage-to-keep-aircraft-on-centerline-during-taxi&quot;&gt;this question&lt;/a&gt; and the FAA's &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-6of7.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Airplane Flying Handbook&lt;/a&gt; ).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can also look up a list of recent taxiing incidents &lt;a href=&quot;http://www.asias.faa.gov/pls/apex/f?p=100:11:0::NO:::&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-05-14T00:40:57.183" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27524" PostTypeId="2" ParentId="27522" CreationDate="2016-05-14T06:57:16.940" Score="1" Body="&lt;p&gt;You will have to comply with the minimum horizontal separation required by the regulations before crossing their levels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS might consider them clear of conflict before they have the minimum horizontal separation required (3, 5, 8Nm, whatever that may be), but remember TCAS is not a way of providing ATC separation.&lt;/p&gt;&#xA;" OwnerUserId="14905" LastActivityDate="2016-05-14T06:57:16.940" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27525" PostTypeId="2" ParentId="27522" CreationDate="2016-05-14T07:34:52.993" Score="5" Body="&lt;p&gt;It depends wether you get procedural or radar service. In case of procedural service if both pilots report clear of traffic (beeing previously informed of the traffic) the longitudinal sepparation criteria is met. &#xA;In case of radar service longitudinal sepparation minimas can vary from 5 to 10 NM or more.&lt;/p&gt;&#xA;" OwnerUserId="7214" LastActivityDate="2016-05-14T07:34:52.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27527" PostTypeId="1" CreationDate="2016-05-14T14:02:01.423" Score="14" ViewCount="1919" Body="&lt;p&gt;I wondered whether the final scene in The Memphis Belle where they hurry to extend the gear by hand crank (because their electric system failed) is realistic, but according to &lt;a href=&quot;https://aviation.stackexchange.com/a/16915/524&quot;&gt;this answer&lt;/a&gt; the B-17 indeed used a hand crank for manual gear extension.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But why did it (and other aircraft of the era that used similar system) need to manually crank the gear all the way down rather than just pull a latch out and let gravity do the rest, like modern systems generally work?&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-05-15T10:52:20.340" Title="Why did some aircraft use hand-crank instead of gravity for alternate gear extension?" Tags="&lt;emergency&gt;&lt;aviation-history&gt;&lt;landing-gear&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27528" PostTypeId="2" ParentId="27527" CreationDate="2016-05-14T14:15:03.360" Score="14" Body="&lt;p&gt;They had to manually crank down the gear because the electric system was damaged. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Memphis_Belle_(film)&quot;&gt;&quot;As the B-17 limps closer to base, Dearborn orders the landing gear dropped. Only one wheel descends due to electrical failure caused by battle damage, but the crew are able to manually lower the malfunctioning wheel just before landing.&quot; &lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Free fall only works for hydraulic powered landing gear systems. The B-17 uses an electrically driven motor to raise and lower the gear. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not all hydraulic landing gear can free fall. PBY-5A's have hydraulic gear and emergency gear extension used a backup hydraulic pump. Additionally you could manually break the up locks and then manually push the gear to the locked position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I bet many other WWII era aircraft with hydraulic gear were similar. Free falling hydraulic gear probably came much later.     &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-05-14T22:31:54.290" LastActivityDate="2016-05-14T22:31:54.290" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27529" PostTypeId="2" ParentId="27486" CreationDate="2016-05-14T16:46:35.650" Score="4" Body="&lt;p&gt;I found something relevant buried in the depths of &lt;a href=&quot;https://www.nbaa.org/ops/airspace/issues/call-signs/JO-7340.2E.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7340.2&lt;/a&gt; on contractions (i.e. abbreviations) for airlines, aircraft types etc. Section 1-4-2 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The company designator, together with a flight number, serves as the&#xA;  aircraft identification in the ATC system. Company designators are&#xA;  valid only for company business in accordance with the provisions of&#xA;  its operating certificate or servicing organization. Pilots will use&#xA;  standard identification procedures for personal flying&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Compare that to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/27486/what-are-the-faa-requirements-for-when-to-use-an-airline-call-sign-flight-numb#comment67822_27486&quot;&gt;quote from your safety organization&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;commercial flights are always conducted under a flight number, and&#xA;  private operations (e.g. repositioning flights) are always conducted&#xA;  under the aircraft registration number.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If you remove the words &quot;e.g. repositioning flights&quot; then it's saying almost exactly the same thing. What's really odd is that the checklist uses repositioning as an example of a &quot;private operation&quot; (the JO uses the words &quot;personal flying&quot;, which has different connotations). I think most people would say repositioning is definitely company business. Perhaps it's just sloppy wording or a poorly chosen example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the safety organization's claim that there are specific requirements in 8900.1, I &lt;a href=&quot;http://fsims.faa.gov/PICResults.aspx?mode=Search&amp;amp;q=%22call%20sign%22&amp;amp;kw=%22call%20sign%22&amp;amp;status=a&amp;amp;syn=1&amp;amp;sort=0&amp;amp;searchwv=0&amp;amp;searchfuzzy=0&amp;amp;&quot; rel=&quot;nofollow noreferrer&quot;&gt;couldn't find anything&lt;/a&gt;. The only vaguely similar thing I found is the 'use it or lose it' clause in 2-275:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;B.    Failure to Use Three-Letter Company Designator and Telephony&#xA;  Designator.&lt;/strong&gt; ATO AJV-2 will place on a watch list any company that does&#xA;  not use an assigned three-letter company designator and telephony&#xA;  designator for 2 years on an instrument flight rules (IFR) flight plan&#xA;  in U.S.-controlled airspace. ATO AJV-2 will revoke and release any&#xA;  three-letter company designator and telephony designator that are not&#xA;  used for 3 years on an IFR flight plan in U.S.-controlled airspace.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Whoever wrote your checklist &lt;em&gt;might&lt;/em&gt; be saying that you need to make sure that you're using your company call sign regularly to make sure you don't have it revoked, but that seems like a real stretch to me. And even if that is the case, it wouldn't explain why repositioning flights should be different. Since 8900.1 is a very large reference library, I'd ask the safety guys to point you to the exact document and wording.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looking in the other usual sources (FARs, AIM, P/CG, ATC orders etc.) that you and &lt;a href=&quot;https://aviation.stackexchange.com/users/12623/ron-beyer&quot;&gt;Ron&lt;/a&gt; mentioned, I couldn't find any specific legal or regulatory requirements either. Almost every reference in FAA sources says &quot;registration or call sign&quot; or something similar (e.g. the AIM's instructions on filing flight plans), and the FCC regulations allow either in radio use (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr;rgn=div5;view=text;node=47%3A5.0.1.1.2;idno=47;cc=ecfr#se47.5.87_1107&quot; rel=&quot;nofollow noreferrer&quot;&gt;47 CFR 87.107&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-14T16:46:35.650" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27532" PostTypeId="2" ParentId="19446" CreationDate="2016-05-14T23:12:13.430" Score="50" Body="&lt;p&gt;Additional details to Marco's selected answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the two-seater version, the instructor seat (aft) is not high enough, contrary to other training aircraft, to see the runway. A forward view mirror replaces the rear view mirror and allows the instructor to see ahead. The runway is projected on a second mirror inside the cockpit, creating a full periscope system:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x6OiO.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x6OiO.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://flickrhivemind.net/flickr_hvmnd.cgi?method=GET&amp;amp;page=4&amp;amp;photo_number=50&amp;amp;tag_mode=all&amp;amp;originput=slovakairforce&amp;amp;search_type=Tags&amp;amp;sorting=Interestingness&amp;amp;photo_type=250&amp;amp;noform=t&amp;amp;search_domain=Tags&amp;amp;sort=Interestingness&amp;amp;textinput=slovakairforce&quot; rel=&quot;nofollow noreferrer&quot;&gt;Photo&lt;/a&gt; by &lt;a href=&quot;https://www.flickr.com/photos/97026550@N00/albums/72157651485454118&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pavel Vanka&lt;/a&gt;. Modified.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/syMZo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/syMZo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.migflug.com/jetflights/wp-content/uploads/2016/02/MiG-29-periscope.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note how the projected part of the image fits very well into the direct view of the exterior.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An opening is created in the canopy when the top mirror is deployed. From below this is what it looks like (not exactly the same model):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/otgm4.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/otgm4.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;&lt;a href=&quot;http://www.b-domke.de/AviationImages/Fulcrum/2161.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Photo&lt;/a&gt; by Burkhard Domk. Modified.&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The bottom mirror unfolds down to instructor eyes height:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/v9k1p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/v9k1p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.strizhi.ru/cgi-bin/yabb/YaBB.pl?num=1044026226/40&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-01-18T09:05:26.287" LastActivityDate="2019-01-18T09:05:26.287" CommentCount="7" ContentLicense="CC BY-SA 4.0" />
  <row Id="27533" PostTypeId="2" ParentId="27521" CreationDate="2016-05-14T23:14:49.237" Score="10" Body="&lt;p&gt;The best explanation I've heard is that at high angles of attack the rudder is nearly vertical providing the pilot better yaw authority.  I don't know whether this is true or not but it makes for a good story, doesn't it?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The story goes something like this:&lt;br&gt;As the plane pitches up, the rudder, being slanted &quot;forward,&quot; moves closer to a vertical position and provides better directional control at low speeds.  Conversely, at high angles of attack a swept tail (and rudder) moves further away from a vertical position and is, in theory, less effective.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some go on to speculate that the leading edge of the vertical stab, being un-swept, protrudes further into undisturbed airflow at high AOA/low airspeeds which may slightly enhance the pilot's ability to control yaw at the edge of a stall.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never spun a Mooney (I did complete my CFI in an M20F/201) nor do I have a burning desire to do so.  I imagine that it's not a friendly spinner.  Catching the spin early would be critical in a slippery air frame like a Mooney.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A brief online search of Mooney tail lore yields everything from pure marketing to discussion of wetted area to better directional control during landing to spin recovery/prevention to &quot;those swept tails provide no speed benefit and are simply designed to look good.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is one discussion (of many) on a Mooney forum regarding the tail design: &lt;a href=&quot;http://mooneyspace.com/topic/9905-mooney-tail-aerodynamics-not-backwards/&quot; rel=&quot;noreferrer&quot;&gt;http://mooneyspace.com/topic/9905-mooney-tail-aerodynamics-not-backwards/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I doubt very much that it's simply a marketing gimmick (although, it could be as simple as that!).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe that the explanation I've relayed here is merely &lt;strong&gt;&lt;em&gt;&quot;somewhat plausible&quot;&lt;/em&gt;&lt;/strong&gt; as it was gleaned from hours of beer-fueled hangar talk and some Google searching...not exactly a scientifically rigorous method of research.  I have no credible references and, as far as I know, no data exists to back any of it up.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-09-24T23:10:07.867" LastActivityDate="2016-09-24T23:10:07.867" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27535" PostTypeId="1" AcceptedAnswerId="27536" CreationDate="2016-05-15T03:56:26.737" Score="6" ViewCount="1077" Body="&lt;p&gt;How did the performance of jets in World War II compare to the cutting edge propeller planes (e.g. P-51, Zero's, etc) of the day?&lt;/p&gt;&#xA;" OwnerUserId="3369" LastEditorUserId="14661" LastEditDate="2016-05-16T01:26:46.310" LastActivityDate="2020-01-21T23:36:23.237" Title="How did jet engine aircraft perform compared to the best reciprocating engine aircraft during WW2?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;jet&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27536" PostTypeId="2" ParentId="27535" CreationDate="2016-05-15T05:14:50.960" Score="12" Body="&lt;p&gt;Much longer take-off distance and less endurance, but higher speed at all altitudes with jets. The performance advantage of jets widened with increasing altitude and resulted in a higher service ceiling. Both the &lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot; rel=&quot;nofollow noreferrer&quot;&gt;Me-262&lt;/a&gt; and the &lt;a href=&quot;https://en.wikipedia.org/wiki/Arado_Ar_234&quot; rel=&quot;nofollow noreferrer&quot;&gt;Ar-234&lt;/a&gt; would fly at least 100 km/h faster than any propeller airplane, and the Ar-234 could fly reconnaissance missions over France and England in complete impunity. A Me-262 test variant (262 V9) with a low-profile canopy reached 600 MPH in level flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This gave jets the possibility to break off combat at will. They could only be engaged with success when they were flying in for a landing with empty tanks or by chance, when the jet pilot was unaware of his opponent. Since the Me-262 was designed to intercept bomber formations, it was not suited for dogfights. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Heinkel_He_280&quot; rel=&quot;nofollow noreferrer&quot;&gt;Heinkel He-280&lt;/a&gt;, on the other hand, was evaluated in 1943 against a FW-190 and would easily outturn the propeller aircraft, so this was not an engine-related characteristic.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that the first kill of a Me-262 was by a de Havilland Mosquito, a very fast propeller aircraft that could outrun almost all other propeller aircraft of its time.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="31425" LastEditDate="2020-01-21T23:36:23.237" LastActivityDate="2020-01-21T23:36:23.237" CommentCount="9" ContentLicense="CC BY-SA 4.0" />
  <row Id="27537" PostTypeId="1" CreationDate="2016-05-15T06:08:30.510" Score="9" ViewCount="680" Body="&lt;p&gt;What is the best airfoil shape for flight in ground effect over water? &lt;/p&gt;&#xA;" OwnerUserId="14912" LastEditorUserId="14661" LastEditDate="2016-05-23T10:01:12.543" LastActivityDate="2019-05-09T18:04:05.810" Title="What is the best combination of airfoil shape for flight in ground effect over water?" Tags="&lt;aircraft-design&gt;&lt;lift&gt;&lt;wing-tip-vortex&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27538" PostTypeId="2" ParentId="27522" CreationDate="2016-05-15T07:08:45.160" Score="7" Body="&lt;p&gt;Yes, this is allowed, subject to certain conditions. See &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot; rel=&quot;noreferrer&quot;&gt;FAA Order 7110.65&lt;/a&gt; (the ATC &quot;bible&quot;), section 5-5-7, for the full details.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...all other approved separation may be&#xA;  discontinued and passing or diverging separation applied when ... Aircraft are on opposite/reciprocal courses and you have observed that they have passed each other; or aircraft are on same or crossing courses/assigned radar vectors and one aircraft has crossed the projected course of the other, and the angular difference between their courses/assigned radar vectors is at least 15 degrees.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's in the terminal environment; it's still possible in the enroute environment but a bit more restrictive due to the greater aircraft speeds and poorer radar accuracy.&lt;/p&gt;&#xA;" OwnerUserId="3417" LastActivityDate="2016-05-15T07:08:45.160" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27540" PostTypeId="2" ParentId="27527" CreationDate="2016-05-15T10:52:20.340" Score="-2" Body="&lt;p&gt;&lt;strong&gt;Because of wind pressure&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Disengaging locks will result in landing gear to partially open but gravity is not strong enough to make the gears lock in their extended position. Wind blast or wind pressure will oppose the movement of landing gear and to actually make the gears extend fully when main system has failed, hand crank is the better option as opposed to relying on gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also modern systems do not solely rely on gravity!&lt;/p&gt;&#xA;" OwnerUserId="14913" LastActivityDate="2016-05-15T10:52:20.340" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27541" PostTypeId="1" CreationDate="2016-05-15T13:00:28.853" Score="1" ViewCount="587" Body="&lt;p&gt;I've flown a piper cadet arrow. The airplane has an engine of 200 horsepower at 2700 RPM. According to the power setting table in the POH, the maximum power we can set is 75% horsepower. With 100% power, we could fly faster (more fuel would burn though). Why doesn't the manufacturer provide the 100% power setting?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="1467" LastEditDate="2016-05-15T13:27:01.060" LastActivityDate="2016-05-15T19:24:41.503" Title="Why is there no 100% power in the POH power setting table?" Tags="&lt;piston-engine&gt;&lt;poh&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ClosedDate="2016-05-15T22:15:25.183" ContentLicense="CC BY-SA 3.0" />
  <row Id="27542" PostTypeId="2" ParentId="27541" CreationDate="2016-05-15T13:18:24.873" Score="1" Body="&lt;p&gt;100% power on a typical aircraft engine is only good for short durations like takeoff or emergency maneuvers. Sustained 100% power setting will destroy the engine. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not to mention flying faster is not always a good thing. It means higher aerodynamic loads on the airplane. Especially when you hit some turbulence.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="609" LastEditDate="2016-05-15T19:24:41.503" LastActivityDate="2016-05-15T19:24:41.503" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27543" PostTypeId="2" ParentId="27541" CreationDate="2016-05-15T13:38:43.517" Score="3" Body="&lt;p&gt;There are no 100% power setting tables because it is impossible to cruise at 100% power with a normally aspirated engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;100% power is rarely available, even at takeoff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is only available at sea level when the temperature is 15C and the altimeter setting is 29.92&quot;. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-05-15T13:38:43.517" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27544" PostTypeId="1" CreationDate="2016-05-15T15:31:02.237" Score="40" ViewCount="7137" Body="&lt;p&gt;Today, commercial aircraft cockpit is manned by 2 pilots, previously  it was 3 to 5. Is safety compromised in any way?&lt;/p&gt;&#xA;" OwnerUserId="14916" LastEditorUserId="524" LastEditDate="2016-05-16T12:24:31.817" LastActivityDate="2017-06-29T21:35:09.600" Title="Is 3 crew cockpit safer than 2 crew?" Tags="&lt;safety&gt;&lt;commercial-aviation&gt;&lt;aviation-history&gt;&lt;crew&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27545" PostTypeId="2" ParentId="27544" CreationDate="2016-05-15T15:47:43.980" Score="11" Body="&lt;p&gt;Back before satellite navigation, affordable inertial navigation systems and small digital computers people had to do the tasks which are now automated. Navigation on long overwater flights was done by sextant, engines were managed by a flight engineer, etc. More people were needed because the jobs could not be done in any other way&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Nowadays computers very efficiently handle many of the tedious and complex tasks, so there simply is not a need for additional cockpit crew. As for whether safety is compromised I would suggest you look at the accident rate over time as it's much lower than it used to be. As for how much of that is due to better automation in the cockpit I cannot say, but it certainly has not increased the accident rate. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-05-15T15:47:43.980" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27546" PostTypeId="1" AcceptedAnswerId="27547" CreationDate="2016-05-15T16:11:19.327" Score="5" ViewCount="23160" Body="&lt;p&gt;In military aviation, crews will sometimes refer to &quot;angels&quot; meaning MSL altitude. However, one might guess that it is a pronunciation of AGL (&lt;strong&gt;A&lt;/strong&gt;n&lt;strong&gt;G&lt;/strong&gt;e&lt;strong&gt;L&lt;/strong&gt;), above ground level. Did it originally mean AGL and then at some point it changed meaning to MSL?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-05-15T17:36:46.490" LastActivityDate="2019-07-07T06:17:32.243" Title="Why do &quot;angels&quot; mean MSL, not AGL?" Tags="&lt;military&gt;&lt;terminology&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27547" PostTypeId="2" ParentId="27546" CreationDate="2016-05-15T16:14:58.937" Score="17" Body="&lt;p&gt;It was originally Royal Air Force slang for altitude in thousands and not a way of pronouncing AGL.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Up in the air, where the angels fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/RAF_slang&quot;&gt;https://en.wikipedia.org/wiki/RAF_slang&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Angels 10 meant 10,000 feet.  Cherubs were hundreds of feet.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-05-15T20:17:07.073" LastActivityDate="2016-05-15T20:17:07.073" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27548" PostTypeId="2" ParentId="27544" CreationDate="2016-05-15T16:26:22.320" Score="57" Body="&lt;p&gt;&lt;strong&gt;No aircraft ever had more than two &lt;em&gt;pilots&lt;/em&gt;&lt;/strong&gt; (on duty at the same time).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The additional flight crew members were flight engineer, navigator and radio operator.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Dedicated radio operators were only needed in the early days when the radio was primitive and required some care and experience to tune properly. As it improved, operating radio was merged into navigator or flight engineer job and eventually became simple enough for pilots to do themselves.&lt;/li&gt;&#xA;&lt;li&gt;Navigators were used on long-distance flights especially over water. They kept track of the progress on the map and corrected the position using celestial navigation and some landmarks where available. With advent of inertial navigation systems and long range radio this simplified enough that dedicated crew member was not needed any more.&lt;/li&gt;&#xA;&lt;li&gt;Flight engineer was most common and remained longest. Engines had many gauges that needed monitoring and controls that had to be correctly set to start them and adjusted to keep them running efficiently. And while turbine engines are simpler to manage than piston ones, the addition of more electric and hydraulic system meant that there was still a lot to set up and monitor. But now this job is done by a computer that monitors all the parameters and displays specific messages when something fails including instructions what needs to be checked and done for each problem.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In the meantime, the improvements in autoflight systems freed more time for the pilots in which they can now handle, with help of the electronics, the tasks that before needed a dedicated crew member.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to these technological advances allowing for the removal of these crew members, overall flight safety has not been compromised. It is likely that safety has actually &lt;em&gt;improved&lt;/em&gt; by reducing the probability of human error.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-09-08T19:13:55.267" LastActivityDate="2016-09-08T19:13:55.267" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27549" PostTypeId="2" ParentId="27546" CreationDate="2016-05-15T17:27:15.687" Score="8" Body="&lt;p&gt;No, it always meant altitude and altitude means above mean sea level since it is distinguished:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Back in 1930s and 1940s when the term was already in use, there was no way to find height above ground level at all. Even now the radar altimeters only measure height up to few thousand feet.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The term is mainly used to describe position of flights over the battle area, for which you need something that will immediately tell you whether the other flight is above or below you. Altitude is such thing—higher number means above, lower number means below. Height wouldn't work as a flight over mountains can have lower height AGL and still be above you.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-05-16T08:07:13.277" LastActivityDate="2016-05-16T08:07:13.277" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27550" PostTypeId="2" ParentId="27535" CreationDate="2016-05-15T18:16:08.617" Score="5" Body="&lt;p&gt;I don't have much in the way of numbers, but, at least from reading the autobiography of Chuck Yeager (&quot;Yeager: An Autobiography&quot; - &lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/0553256742&quot; rel=&quot;noreferrer&quot;&gt;http://www.amazon.com/Yeager-Autobiography-Chuck/dp/0553256742&lt;/a&gt;) that he shot down an Me 262 (one of Germany's jet fighters) by exploiting a weakness of the aircraft (such as their long landing approaches at relatively slow speeds).  He notes that, as @Peter Kampf says, that it was really hard to engage 262s due to their extremely high speed, but also keep in mind that this doesn't make them a good fighter -- especially not against slower aircraft when both only have guns.  If the aircraft was designed to cruise at high speeds, it would be extremely difficult for it to maneuver at low speeds due to the higher wing loading (e.g., maneuvering loads become higher for a lower airspeed and you become structurally limited on how tight your turns can be).  Hence, a slower aircraft could, potentially, fly circles around such a plane.  If it could convince the jet to slow down in the first place...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, because of their high speed, Yeager notes that they could dive through a bomber formation with relative impunity.  They would not have long to fire on the formation, but it was incredibly difficult to hit the jet fighter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyhow, according to the National Air and Space Museum's website (&lt;a href=&quot;http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19600328000&quot; rel=&quot;noreferrer&quot;&gt;http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19600328000&lt;/a&gt;), the Me-262 had a top speed of 540 mph (unclear if that is in level flight, but I'd believe so).  Looking at a max. level flight speed versus altitude for a P-51B, it never breaks 450 mph (source: &lt;a href=&quot;http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-level-blue.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-level-blue.jpg&lt;/a&gt;).  This performance plot is from an Army performance test in 1943 (source: &lt;a href=&quot;http://www.wwiiaircraftperformance.org/mustang/P-51B_Official_Performance_Figures_15May1943.jpg&quot; rel=&quot;noreferrer&quot;&gt;http://www.wwiiaircraftperformance.org/mustang/P-51B_Official_Performance_Figures_15May1943.jpg&lt;/a&gt;).&lt;/p&gt;&#xA;" OwnerUserId="14720" LastActivityDate="2016-05-15T18:16:08.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27551" PostTypeId="1" AcceptedAnswerId="27566" CreationDate="2016-05-15T19:52:23.430" Score="6" ViewCount="255" Body="&lt;p&gt;In general, does a person's anxiety or &quot;fear of flying&quot; have an effect on his likelihood of experiencing motion sickness during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am wondering if providing some ground education to first-time flyers would have a positive impact on their experience by reducing anxiety levels and, therefore, the chances of needing to use regurgitation collection devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Assume all other factors such as specific G-forces and accelerations experienced, temperatures, meals eaten, etc. are controlled or disregarded.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-16T17:03:14.867" LastActivityDate="2016-05-16T18:52:34.210" Title="Does anxiety increase the likelihood of developing motion sickness?" Tags="&lt;flight-training&gt;&lt;passenger&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27552" PostTypeId="2" ParentId="27546" CreationDate="2016-05-15T20:59:38.833" Score="1" Body="&lt;p&gt;Close to the ground, altitude AGL matters far more than altitude MSL, since it is the ground that you're trying to land on, or avoid running into. At higher altitudes, however, altitude AGL matters far less, and is much harder to determine, and thus altitude MSL is used as the reference. That is also what is read on the barometric altimeter.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, for an aircraft looking to join up with (or avoid hitting) another aircraft, giving the altitude in the same reference (MSL, not AGL) that can be readily read on the instruments is most useful.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Besides, if that aircraft is over a mountain and I'm over a valley, we might be at the same altitude even though he is at 4000' AGL (above the ground directly beneath him) while I'm at 6000' AGL (above the ground beneath me).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One might ask, why not set QFE and reference everything to the &quot;ground level&quot; at some particular airport, rather than referencing everything to sea level.  You could do that, AS LONG AS everybody has the same QFE for the day.  If you're doing all your flying in a theater where all the airfields are at about the same altitude, this probably wouldn't cause much problem, but if I have QFE set for the field I took off from (elevation 10' MSL), that setting won't show me what I want to see if I end up landing at another field at say 500' MSL!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, the fairly common choice to set altimeters to read height above sea level, and thus reference calls of other aircraft altitude to that same standard.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-15T20:59:38.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27554" PostTypeId="1" AcceptedAnswerId="27557" CreationDate="2016-05-16T02:17:02.663" Score="30" ViewCount="5040" Body="&lt;p&gt;I was recently reading about the MiG-29 and its many upgrades, one of which (MiG-29M) was to smokeless engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What makes a smokeless jet engine? Is it just the fuel, or something about the way the engine works itself?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've observed smokey engines were more common in the past and I'm wondering why that is too. Were they just easier to build for some reason?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2016-05-17T04:21:14.407" Title="What makes a smokeless jet engine?" Tags="&lt;jet-engine&gt;&lt;military&gt;&lt;fuel&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27555" PostTypeId="2" ParentId="27554" CreationDate="2016-05-16T03:34:00.367" Score="26" Body="&lt;p&gt;Generally, smoke comes from incomplete burned fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally, a jet engine burns a very lean mixture (due to turbine temperature constraints). Nevertheless, getting all the fuel to burn is a considerable challenge, primarily because the air/mixture flows faster in the engine than the flame front. So in order to provide stable burn, many tricks come into play: the combustion chamber expands after the compressor; there are special vortex generators that force the mixture to backflow and circulate; the air may be fed in stages along the chamber, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This complicated gas dynamics is difficult to optimise, especially in the 70s when MiG-29's engines (RD-33) were designed. What usually happens is that there are pockets of over-rich mixture in the combustion chamber, and the extra fuel decomposes due to high temperature before it has an opportunity to burn.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From what I know, RD-33MK got a redesigned combustion chamber (amongst other things), but what exactly the changes are is hard to say. I can speculate that the source of the original problem was that RD-33 had an early example of the &lt;em&gt;annular&lt;/em&gt; combustion chamber, which was not well studied then. But the problem was bad enough to make MiG-29 more easily detectable in visual fight.&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-05-16T03:34:00.367" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27556" PostTypeId="2" ParentId="27234" CreationDate="2016-05-16T04:28:00.710" Score="1" Body="&lt;p&gt;If a pair of jet aircraft is approaching an airport, does the separation distance between them is the same or larger, under CDA and Non-CDA scenario?&#xA;Ans: Same. U.S. separation starts are in FAA Order 7110.65. It has one set of standards&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just before touchdown on runway, does the aircraft approach speed is the same, under CDA and Non-CDA scenario?&#xA;Ans: Generally the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, how much track miles could be used for approaching traffic at a major airport? &#xA;Ans: Many instrument approaches are defined for 15 NM (the Initial Approach Fix). However, often aircraft are cleared to the Intermediate Fix, about 10 NM from the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In general, is the airspeed during descent differs CDA and Non-CDA scenario?&#xA;Ans: I don't know.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just before touchdown on runway, will the pilot utilize thrust to increase speed or aircraft will be on its own volition, under CDA and Non-CDA scenario?&#xA;Ans: Just before touchdown, the pilot will generally initiate a flare maneuver to reduce the impact.&lt;/p&gt;&#xA;" OwnerUserId="14736" LastActivityDate="2016-05-16T04:28:00.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27557" PostTypeId="2" ParentId="27554" CreationDate="2016-05-16T05:52:58.167" Score="18" Body="&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/8646/why-does-an-aircraft-leave-a-white-smoke-trail/8653#8653&quot;&gt;Smoke&lt;/a&gt; results from soot in the combustion gasses, so the carbon part of the hydrocarbon fuel was incompletely burned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/3.49345?journalCode=aiaaj&quot; rel=&quot;nofollow noreferrer&quot;&gt;literature&lt;/a&gt; (sorry, paywalled, but you can read the first page) reports that in the first decades of jet engine design much combustor development was trial and error. Specifically, to arrive at a smokeless combustor, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Pratt_%26_Whitney_JT9D&quot; rel=&quot;nofollow noreferrer&quot;&gt;JT9D&lt;/a&gt; team had to perform 465 modifications and 140 full engine tests. Mainly, these tricks help:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Slow flow speeds by careful diffusor design at the compressor exit&lt;/li&gt;&#xA;&lt;li&gt;Swirling of the flow at the combustor entry to improve fuel-air mixing&lt;/li&gt;&#xA;&lt;li&gt;Measured inflow of air into the combustor, such that the fuel injection area has an essentially stoichiometric mixture for best flame stability. Then more air is added in a secondary and a third dilution region. This dilution helps to lower the gas temperature so the gas stream is palatable to the turbine.&lt;/li&gt;&#xA;&lt;li&gt;Longer combustors, so that 99% combustion can be achieved at the end of the secondary region.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Selecting the right fuel helps, too. If you would burn methanol or ethanol, a smokeless combustor is easier to achieve, but the &lt;a href=&quot;https://en.wikipedia.org/wiki/Energy_density#Energy_densities_of_common_energy_storage_materials&quot; rel=&quot;nofollow noreferrer&quot;&gt;energy density&lt;/a&gt; of the fuel suffers. Lighter fuels with shorter hydrocarbon chains help, but are more expensive to produce and reduce energy density, so kerosene was preferred even if its combustion produces soot.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-05-17T04:21:14.407" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27558" PostTypeId="2" ParentId="27489" CreationDate="2016-05-16T08:21:35.253" Score="4" Body="&lt;p&gt;The forward stagnation point is easy to explain: Imagine the flow path of molecules which approach an airfoil. Some will continue above and some below the airfoil contour. Between them there must be one flow path which will neither go above nor below, but hit the airfoil straight on. The point where it hits the airfoil is the &lt;a href=&quot;https://aviation.stackexchange.com/questions/9955/can-a-steady-flow-have-stagnation-points/9958#9958&quot;&gt;stagnation point&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The rear stagnation point is similarly explained: When the flows from above and below meet, there will be a line dividing both. Continue this line forward until it hits the airfoil: This is where the rear stagnation point is located. A rear stagnation point is only possible in inviscid flow, which exists only in theory. In both points the speed of air relative to the airfoil is zero, and air molecules will never completely arrive at the stagnation point, but slow down on their way into it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An airfoil of zero circulation &lt;strong&gt;and zero camber&lt;/strong&gt; will have its rear stagnation point right at the trailing edge. Only when you add asymmetry by giving the airfoil positive camber, the flow has to develop an asymmetric pattern which shifts the rear stagnation point away from the trailing edge to satisfy the zero circulation condition. Give the airfoil negative camber, and the rear stagnation point will duly relocate below the trading edge.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Kutta_condition&quot; rel=&quot;nofollow noreferrer&quot;&gt;Kutta condition&lt;/a&gt; postulates that the rear stagnation point is fixed at the trailing edge. Make the trailing edge blunt and you need to define where precisely your stagnation point will be. Note that your choice of location will influence the circulation at a given angle of attack! The Kutta condition imposes an arbitrarily chosen stagnation point which just helps to explain real flows better. This does not mean that real flows will observe the Kutta condition closely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look for the &quot;real&quot; stagnation point, you should really search for the point where local pressure reaches a maximum, fully knowing that a full deceleration to stagnation will not happen in reality. This can only be outside of the boundary layer, since the energy loss of the boundary layer flow will result in a pressure loss. Now the picture from the second paragraph will help: Find the line separating upper and lower flows and follow it upstream until it hits the airfoil. This procedure will land you straight at the lowest speed section of the boundary layer, and near the airfoil the pressure there is too low. But now move back again and watch how the slow center part of the boundary lower gets accelerated by shear with the neighboring flow. At some point pressure will peak: This is the closest you can come to for a rear stagnation point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Below I plotted a quick XFOIL calculation of a NACA4418 with a 5% trailing edge gap to get something similar to your airfoil. Note how the $c_p$-value of the viscous flow (solid line) peaks at some point behind the blunt trailing edge. For the outer flow the airfoil looks as if it is slightly longer, the void behind the blunt trailing edge being filled by separated, slow flow. Also note that the upper boundary layer is thicker, shifting the &quot;rear stagnation point&quot; a little up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x5eOp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x5eOp.png&quot; alt=&quot;XFOIL Plot of a NACA4412 with 5% blunt trailing edge at 4° AoA&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;XFOIL Plot of a NACA4412 with 5% blunt trailing edge at 4° AoA (own work).&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-05-16T08:21:35.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27559" PostTypeId="2" ParentId="11260" CreationDate="2016-05-16T08:24:22.237" Score="0" Body="&lt;p&gt;Depends on the programming of the drone - mostly if it contains code for autonomous operations. Furthermore, it can have a &quot;drone call home&quot; subroutine which would cause it to become &quot;autonomous&quot; (it isn't fully autonomous, but it can fly on it own in a straight line).&lt;/p&gt;&#xA;" OwnerUserId="14857" LastActivityDate="2016-05-16T08:24:22.237" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27560" PostTypeId="2" ParentId="27414" CreationDate="2016-05-16T08:40:39.953" Score="5" Body="&lt;p&gt;A propeller accelerates air, and the stream tube going through the propeller disc &lt;a href=&quot;https://aviation.stackexchange.com/questions/8819/is-there-any-equation-to-bind-velocity-thrust-and-power?lq=1&quot;&gt;can be idealized&lt;/a&gt; as something which is initially wider than the propeller disc and contracts while being accelerated (&lt;a href=&quot;http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/fprops/cvanalysis/node50.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Froude's propeller hypothesis&lt;/a&gt;). Now two types of obstruction are possible:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Obstructions to the flow near the propeller axis, and&lt;/li&gt;&#xA;&lt;li&gt;Obstructions to the flow near the stream tube.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;It is quite obvious that something which blocks the flow will reduce the propeller's efficiency, and since flow speed is higher behind the propeller, the same obstruction will reduce performance more if placed behind the propeller disc. This is why pusher designs show better performance with the same engine power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But also objects near the outer edge of the propeller can reduce efficiency. When a wall on one side ahead of the propeller prevents air from flowing towards the disc, the flow though the propeller disc is disturbed and efficiency will suffer. Similarly, a wall past the propeller will prevent a symmetric outflow, and the stream tube will attach to the wall (Coanda effect). This can be used to the advantage of high lift devices on wings, but will generally reduce efficiency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For experimental data, I recommend to read NACA reports like the one for &lt;a href=&quot;http://crgis.ndc.nasa.gov/crgis/images/7/70/1940_Cowling_Development.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;engine cowling development&lt;/a&gt; or &lt;a href=&quot;http://crgis.ndc.nasa.gov/crgis/images/c/c6/1928_naca-tn-274.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one on fuselage-propeller interference&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-05-16T08:47:59.347" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27561" PostTypeId="2" ParentId="24390" CreationDate="2016-05-16T09:25:23.583" Score="13" Body="&lt;p&gt;First of all: jets are not &amp;quot;n-propellant&amp;quot;. Rockets are bipropellant. That's because rocket needs to carry fuel and oxidizer, while air-breathing jet gets the oxidizer (plus huge amounts of reaction mass) for free from the air. So jets carry only one propellant (which doesn't make them monopropellant either). The tripropellant rockets were imagined to overcome problems with specific impulse. The most complicated and impractical rocket engine could go as high as 542s - while average jet operates around 3000s easily. So specific impulse is the problem jets never had in the first place.&lt;/p&gt;&#xA;&lt;p&gt;The biggest advantage of RD-701 was to use the kerosene-hydrogen mix on low altitude (where kerosene is more efficient) and then switch to pure hydrogen in space (where hydrogen is more efficient). They started with a hydrogen engine (RD-0120) and then added kerosene to increase efficiency by reducing the amount of hydrogen needed - so the exactly opposite reasoning. The main problem with your idea here is that &lt;strong&gt;jets never leave the kerosene zone&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The main problem of liquid hydrogen is that the fuel is lighter, but the tanks are so heavy it completely obliterates any savings. Rockets here get it easy - rocket working lifetime is measured in minutes (Space Shuttle burn: 8m30s Soyuz burn: bit over 10m50s). A plane on the other hand would need to store the hydrogen for a dozen of hours = even more weight. There is no weight-efficient way of keeping the cryogenic fluid on the go. All you can do is to let some of it &amp;quot;boil-off&amp;quot;. Twice as heavy as kerosene tank is a huge understatement IMHO, as in modern jet liners the tanks - &amp;quot;wet wing&amp;quot; - are almost free (in terms of mass). Can't do that with hydrogen - you'll need to sacrifice cargo space for dedicated LH2 tank.&lt;/p&gt;&#xA;&lt;p&gt;Another issue is that hydrogen burns in higher temperature. We're already having problems with making the turbine survive kerosene temperatures, adding hydrogen would make the engine design even more difficult. From the green perspective it's not all roses either, because the higher combustion temperature, the more NOx created.&lt;/p&gt;&#xA;&lt;p&gt;I have to agree with others here - hydrogen planes won't happen unless we'll run out of easier options. Having 2 kinds of fuel is the most difficult of them all.&lt;/p&gt;&#xA;" OwnerUserId="3903" LastEditorUserId="3903" LastEditDate="2020-09-23T06:46:55.207" LastActivityDate="2020-09-23T06:46:55.207" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="27562" PostTypeId="2" ParentId="25125" CreationDate="2016-05-16T12:18:13.490" Score="1" Body="&lt;p&gt;Paranee,&#xA;There is no such detail in the LDM, it is just a WEIGHT value. There maybe specifics for certain SL/DG (review AHM again for those) as some SL/DG are required to show location and some location and weight - explained in AHM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;BUT - LDM is just an overview, not very specific as it does not need to be. For a through flight A&gt;B&gt;C, where A is OFFLINE to your system, if you have received teletype LDM for processing and you are doing the sector B&gt;C then any load B&gt;C is just shown (know by the system) as TRA (transit) load - nothing more. No more detail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However for unitized aircraft, the CPM complements the LDM to show the detail required by bay as opposed to HOLD and/or COMPARTMENT.&lt;/p&gt;&#xA;" OwnerUserId="14929" LastEditorUserId="1467" LastEditDate="2016-05-16T12:40:03.227" LastActivityDate="2016-05-16T12:40:03.227" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27563" PostTypeId="1" AcceptedAnswerId="27565" CreationDate="2016-05-16T15:49:19.473" Score="9" ViewCount="1615" Body="&lt;p&gt;Obviously for aircraft arriving to or departing from an airport/airspace (as relevant), they listen to the ATIS and/or are given the QNH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what happens if that pressure changes? Even a fairly small change can make a big difference when we're dealing with 1000ft of vertical separation (which can be much less by the time we account for human margins for error).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the new QNH announced to the entire frequency, or similarly the change of ATIS, which each aircraft would then be expected to check? Or would it just be updated when assigning a new altitude to any aircraft already in the airspace?&lt;/p&gt;&#xA;" OwnerUserId="3945" LastActivityDate="2021-02-11T01:38:07.947" Title="How does ATC handle changing QNH/altimeter values?" Tags="&lt;air-traffic-control&gt;&lt;altitude&gt;&lt;separation&gt;&lt;qnh&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27565" PostTypeId="2" ParentId="27563" CreationDate="2016-05-16T16:10:03.167" Score="11" Body="&lt;p&gt;In the US, ATC simply broadcasts a notification on whatever frequency is needed. For the terminal environment, section 2-9-2 of the &lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/ATC.pdf&quot;&gt;ATC orders&lt;/a&gt; says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Broadcast on all appropriate frequencies to advise aircraft of a&#xA;  change in the ATIS code/message.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The phraseology is usually something like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Attention all aircraft, Bowman information Kilo is now current.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;For en route operations (see section 2-7-2) the ARTCC gives altimeter setting updates directly:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Attention all aircraft, the Nashville altimeter now 2992&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-16T16:10:03.167" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27566" PostTypeId="2" ParentId="27551" CreationDate="2016-05-16T18:52:34.210" Score="4" Body="&lt;p&gt;It's different for everyone, but I'd expect stress/anxiety to be a contributing factor for many, which is an ultimately self-defeating cycle; if you &quot;know&quot; you're going to get sick, you'll be anxious about that, and that'll make you sick.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The trigger for me is inadequate ventilation. I'm fortunate enough to rarely get motion sickness, but when it does happen it's usually because I'm in a hot, still cabin without a good source of fresh air. &lt;/p&gt;&#xA;" OwnerUserId="7629" LastActivityDate="2016-05-16T18:52:34.210" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27567" PostTypeId="2" ParentId="27544" CreationDate="2016-05-16T19:52:55.137" Score="10" Body="&lt;p&gt;Your question seems to imply that having an extra hand on deck would help prevent an accident, which is not always true.  Firstly, let's make a historical note that you're far from the first one to ask this question. When the DC-9-80 was being certified there was a heated debate between pilot unions and manufacturers over whether the two pilot crew was sufficiently safe, and a presidential commission tasked to investigate in 1981 &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a106889.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;concluded that&lt;/a&gt;: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The safety record of aircraft flown by crews of two is at least as&#xA;  good as the safety record of aircraft flown by crews of three. In our&#xA;  judgment, the presence of a third crew member in the DC-9-80 would not&#xA;  improve the ability of the crew to operate the aircraft safely in the&#xA;  air traffic environment. Therefore, safety-related improvements must&#xA;  come from measures other than enlarging the size of the flight crew.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The other answers have focused on decreased necessity of an extra crew member for navigation, engine tuning, and radio usage. I'd like to explain in the rest of my answer why having an extra crew member doesn't always prevent mistakes from a &lt;a href=&quot;https://en.wikipedia.org/wiki/Crew_resource_management&quot; rel=&quot;nofollow noreferrer&quot;&gt;crew resource management (CRM)&lt;/a&gt; perspective.  Occasionally in practice the extra crew member made the plane &lt;em&gt;less&lt;/em&gt; safe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CRM developed after some major cases where the flight engineer was ignored by the pilots and a crash resulted.  In these cases the flight engineer certainly didn't prevent the accident. After all, when &lt;a href=&quot;https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401&quot; rel=&quot;nofollow noreferrer&quot;&gt;EAL Flight 401&lt;/a&gt; descended too close to the ground the flight engineer wasn't even in the cockpit to monitor the low altitude alarm that sounded from his station.  In my opinion the flight engineer's presence potentially makes it easier for the pilot to ignore warning signs that are the flight engineer's responsibility.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/United_Airlines_Flight_173&quot; rel=&quot;nofollow noreferrer&quot;&gt;UA 173&lt;/a&gt;, one of the pivotal crashes for CRM, happened during approach when a problem with landing gear extension left the landing gear down and locked, but damaged the landing gear sensor assembly so that the landing gear indicator light did not come on.  The pilots focused on this issue, and ignored the rapidly dwindling fuel supply.  The flight engineer gave repeated hints about the fuel problem but the pilot ignored him.  The NTSB said the pilot failed to monitor the fuel supply and did not take the flight engineer's comments seriously, and the flight engineer was not assertive enough.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The infamous &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow noreferrer&quot;&gt;Tenerife airport disaster&lt;/a&gt; happened when a pilot mistakenly thought he had takeoff clearance in low visibility and collided with a Pan-Am 747 that was still taxiing. The flight engineer of the taking-off plane had asked &quot;Is he not clear, that Pan-American?&quot; to which the pilot simply responded &quot;Oh yes&quot;. The breakdown in CRM prevented the flight engineer from stopping the crash.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Accidents in which a flight engineer caused or failed to prevent an accident have greatly been mitigated by the improvements in CRM, but they still happen.  In 2011, &lt;a href=&quot;https://en.wikipedia.org/wiki/RusAir_Flight_9605&quot; rel=&quot;nofollow noreferrer&quot;&gt;RusAir Flight 9605&lt;/a&gt; crashed after the navigator had been giving mistaken directions and was even intoxicated, but the pilot did not question his guidance.  Once again, the flight engineer may have made it easier for the pilot to ignore warning signs due to a breakdown in effective CRM.  This was a similar situation to the 1996 &lt;a href=&quot;https://en.wikipedia.org/wiki/Charkhi_Dadri_mid-air_collision&quot; rel=&quot;nofollow noreferrer&quot;&gt;Charkhi Dadri mid-air collision&lt;/a&gt; that TomMcW pointed out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The President's Task Force on Aircraft Crew Complement similarly &lt;a href=&quot;http://www.dtic.mil/dtic/tr/fulltext/u2/a106889.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;concluded that&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;there is no advantage to any particular crew size in relation to safe&#xA;  and effective cockpit resource management. We also interpret incident,&#xA;  accident, and relevant research data to indicate that it is more&#xA;  difficult to achieve effective crew integration with larger crews.&#xA;  Distractions... should&#xA;  be dealt with by instituting more effective operational controls&#xA;  rather than by using a larger operating crew.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In summary, having an extra set of hands in the cockpit only helps safety when the crew is communicating effectively and using proper CRM.  Quite a few flight engineers have failed to prevent or have even caused a crash.&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="14613" LastEditDate="2017-06-29T21:35:09.600" LastActivityDate="2017-06-29T21:35:09.600" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27568" PostTypeId="2" ParentId="3513" CreationDate="2016-05-16T19:56:21.840" Score="3" Body="&lt;p&gt;Matt got a lot of it right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Dynamic compressors and turbines tend to get less efficient as their sizes decrease, because of Reynolds' number effects and because of limits on materials and manufacturing.  To get a good stage pressure ratio in a compressor, a tip speed of at least 300 m/s is required;  exceeding 500 m/s is not unheard of.  Since the centripetal acceleration is inversely proportional to radius at constant tip speed, centripetal loads can be too high for most materials.  Tip clearances have to be small -- about 1% of tip chord -- for best efficiency, high temperatures demand cooled blades and vanes in the hot end, and that means that blades and vanes have to have cooling passages inside the blade.  This is easier in a PW4084 than an Allison 250, as the PW's blades are a lot bigger.&lt;/p&gt;&#xA;" OwnerUserId="13301" LastActivityDate="2016-05-16T19:56:21.840" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27569" PostTypeId="1" AcceptedAnswerId="27572" CreationDate="2016-05-16T22:11:34.840" Score="16" ViewCount="6062" Body="&lt;p&gt;Doing some of my airplane learning, I have come across a point many times that the engines for the Boeing 747 (at least partially) came from Boeing's competitor to the C-5 Galaxy. What was this plane that Boeing had made to compete with the C-5?&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="14897" LastEditDate="2020-04-22T11:05:05.210" LastActivityDate="2020-04-22T11:05:05.210" Title="What was Boeing's competitor to the C-5?" Tags="&lt;aviation-history&gt;&lt;boeing&gt;&lt;lockheed-c-5&gt;" AnswerCount="2" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27570" PostTypeId="2" ParentId="27441" CreationDate="2016-05-16T23:27:20.337" Score="1" Body="&lt;p&gt;2 cents here: One of the first homework assignments of our aerodynamics class was to calculate the lift of an airfoil by using the pressure data of the wind tunnel walls. Any wing shape would generate a pressure variation (if it's generating lift) at the boundaries of the tunnel. (Unmeasurable it may be)&lt;/p&gt;&#xA;" OwnerUserId="8079" LastActivityDate="2016-05-16T23:27:20.337" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27571" PostTypeId="1" AcceptedAnswerId="27573" CreationDate="2016-05-17T00:08:56.930" Score="18" ViewCount="1123" Body="&lt;p&gt;I wonder about sonic boom existence and effects when two fast aircraft interact, for example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When supersonic aircraft flying opposite routes cross each other, do pilots hear a sonic boom?&lt;/li&gt;&#xA;&lt;li&gt;If they fly in the same direction, with the appropriate offset, does one hear a permanent sonic boom?&lt;/li&gt;&#xA;&lt;li&gt;If two aircraft fly in opposite directions at Mach 0.6, can they create a sonic boom by adding their individual shockwave speeds?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/DdjzR.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/DdjzR.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Two Sukhoi Su-30MKI maneuvering, &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_combat_manoeuvring&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Further than the sound aspect:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;What are the effects on the aircraft?&lt;/li&gt;&#xA;&lt;li&gt;Is there a distance after which the effects become insignificant?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2019-12-04T01:25:02.950" LastActivityDate="2019-12-04T01:25:02.950" Title="What does happen when a supersonic aircraft passes another supersonic aircraft, regarding sonic booms?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="27572" PostTypeId="2" ParentId="27569" CreationDate="2016-05-17T01:55:14.060" Score="18" Body="&lt;p&gt;In 1964 the US Air Force awarded study contracts for a new cargo aircraft to Boeing, Douglas and Lockheed. The aircraft was called CX-HLS. ( cargo experimental - heavy logistics system)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lockheed won with the C-5A design. Boeing's design was never built but would have looked like this:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/uZwlY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uZwlY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;source: &lt;a href=&quot;http://widebodyaircraft.nl/chro1963.htm&quot; rel=&quot;noreferrer&quot;&gt;Widebody Aircraft Chronology&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Sx04f.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Sx04f.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source: Boeing archives&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Dmc2N.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Dmc2N.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Source:&lt;a href=&quot;http://www.tdpri.com/threads/since-were-on-a-roll-native-speakers-boeing-seven-four-seven-or-seven-forty-seven.563541/#post-6425836&quot; rel=&quot;noreferrer&quot;&gt;TDPRI.COM&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="946" LastEditDate="2016-05-19T04:13:23.073" LastActivityDate="2016-05-19T04:13:23.073" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27573" PostTypeId="2" ParentId="27571" CreationDate="2016-05-17T05:13:26.880" Score="8" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;When supersonic aircraft flying opposite routes cross each other, do pilots hear a sonic boom?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If the aircraft are near enough, yes.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If they fly in the same direction, with the appropriate offset, does one hear a permanent sonic boom?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The boom will not be permanent i.e. static, but yes, it will be persistent. However, it should be noted that the shocks from various parts of the aircraft body will interact nonlinearly (mostly coalsce), resulting in unpredictable results. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If two aircraft fly in opposite directions at Mach 0.6, can they create a sonic boom by adding their individual shockwave speeds?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;No, sonic boom is caused by the object travelling faster than sound while the disturbances travel in the medium with speed of sound and get 'bunched up'. So, the aircraft has to fly supersonic &lt;em&gt;with respect to the medium&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the effects on the aircraft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Shock wave is basically a pressure discontinuity. So the effect will be similar to that of an impact, whose strength depends on the shock wave.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Is there a distance after which the effects become insignificant?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, but it depends on the aircraft size and the speed. The shock wave produced by the bullet loses its strength in a short distance, while the Concorde has to be flown over sea and Tu-144 at over 35000' to mitigate the effects.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="12220" LastEditDate="2016-05-17T05:22:43.193" LastActivityDate="2016-05-17T05:22:43.193" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27574" PostTypeId="1" CreationDate="2016-05-17T05:36:31.737" Score="9" ViewCount="4413" Body="&lt;p&gt;I'm trying to figure out when it is safe to continue at normal cruise speed and when I should slow down to avoid over-stressing the airframe due to turbulence. (of course I have asked instructors but I'd like to get some more opinions)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My aircraft has a maneuvering speed listed, Va, also listed as the turbulence penetration speed. When should I actually slow down to this speed (i.e. light, moderate, severe turbulence)? How long should such turbulence occur before I slow down (after a bump or two, when the turbulence is observed to be intermittent or continuous, should I slow down immediately)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For the scope of this question I'm asking specifically about light single-engine general aviation aircraft that cruise around 140 kts. Va is 112 kias. I'd be interested in hearing about larger/smaller aircraft too though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answers from actual pilots with experience in this area, please (I would hope all pilots have some :-) ).&lt;/p&gt;&#xA;" OwnerUserId="8531" LastEditorUserId="8531" LastEditDate="2016-05-17T05:44:34.623" LastActivityDate="2016-05-18T19:47:10.293" Title="When to slow down to Va for turbulence?" Tags="&lt;airspeed&gt;&lt;turbulence&gt;" AnswerCount="3" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27575" PostTypeId="2" ParentId="3513" CreationDate="2016-05-17T05:43:26.867" Score="1" Body="&lt;p&gt;For me, the answer is money. A P&amp;amp;W PT-6 turbine engine is going to run you between \$500,000 USD and \$750,000 USD to be overhauled. A turbocharged piston engine, even a very expensive one, isn't going to cost more than about \$50,000 USD to overhaul. Other than that, for certain missions such as over-water/mountain operations I'd take the fuel burn for reliability and weight savings trade-off in a small plane, though you can expect to burn 2 to 3 times more fuel in a small turbine vs a large piston. Note that there are many piston types that have STCs available to replace the standard piston engine with an aftermarket piston, but as I mentioned the costs are relatively astronomical to do so. For example, the Silver Eagle Cessna 210. &lt;a href=&quot;http://www.onaircraft.com/the-planes/the-silver-eagle-ii/&quot; rel=&quot;nofollow&quot;&gt;http://www.onaircraft.com/the-planes/the-silver-eagle-ii/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8531" LastActivityDate="2016-05-17T05:43:26.867" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27576" PostTypeId="1" AcceptedAnswerId="27579" CreationDate="2016-05-17T06:13:35.693" Score="10" ViewCount="3107" Body="&lt;p&gt;I was watching the video of the &lt;a href=&quot;http://www.abc.net.au/news/2016-05-16/antonov-an-225--mriyn-perth-airport/7416958&quot;&gt;AN 225 unloading at Perth airport&lt;/a&gt; this weekend, and it suddenly occurred to me that there are about a zillion rear wheels on the aircraft, yet only 2 nose wheels? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This might make sense in a normal airliner, but in this one, the whole weight of the 117 Tonne generator is passed over the front wheels, as it is unloading?&lt;/p&gt;&#xA;" OwnerUserId="14940" LastEditorUserId="12220" LastEditDate="2016-05-17T06:41:52.210" LastActivityDate="2016-05-17T18:47:36.303" Title="How can the Antonov AN 225 only have 2 nose wheels?" Tags="&lt;landing-gear&gt;&lt;weight-and-balance&gt;&lt;antonov-225&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27577" PostTypeId="1" AcceptedAnswerId="27580" CreationDate="2016-05-17T08:12:38.800" Score="5" ViewCount="1059" Body="&lt;p&gt;I got an exercise where IATA codes are involved - exercise's specification says those codes can be 2-4 letters. After a few minutes of research I see that those codes should be 3 letters, so c&lt;strong&gt;an IATA code for an airport be more or less than 3 letters&lt;/strong&gt;?&lt;/p&gt;&#xA;" OwnerUserId="12891" LastEditorUserId="12891" LastEditDate="2016-05-17T09:41:34.293" LastActivityDate="2021-04-24T02:34:32.463" Title="Can IATA code for an airport be more or less than 3 letters?" Tags="&lt;iata&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27578" PostTypeId="1" AcceptedAnswerId="27599" CreationDate="2016-05-17T08:26:29.670" Score="8" ViewCount="1406" Body="&lt;p&gt;Yesterday I was spotting at Barcelona International (&lt;a href=&quot;https://skyvector.com/airport/LEBL/Barcelona-El-Prat-Airport&quot; rel=&quot;nofollow&quot;&gt;LEBL&lt;/a&gt;). I noticed that at least two airliners were approaching with their landing lights OFF, just to light them on very short final (about 0.4NM from runway threshold).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I thought landing lights were required to be ON at all times below 10000 feet. Am I wrong? Is there any situation when landing lights are not required below 10000 feet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Visibility was excellent, &lt;strike&gt;I'm going to see if I can find the actual METARs but I would say CAVOK conditions.&lt;/strike&gt; see the METARs:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&#xA;LEBL 161630Z 17007KT 140V210 CAVOK 19/11 Q1019 NOSIG&#xA;LEBL 161700Z 20007KT 150V230 CAVOK 19/11 Q1019 NOSIG&#xA;LEBL 161730Z 22007KT 170V240 CAVOK 19/12 Q1019 NOSIG&#xA;LEBL 161800Z 21007KT CAVOK 18/12 Q1019 NOSIG&#xA;LEBL 161830Z 20005KT 170V230 CAVOK 18/12 Q1020 NOSIG&#xA;LEBL 161900Z 21005KT CAVOK 17/12 Q1020 NOSIG&#xA;&lt;/pre&gt;&#xA;" OwnerUserId="424" LastEditorUserId="19" LastEditDate="2016-11-21T09:05:57.867" LastActivityDate="2016-11-21T09:05:57.867" Title="Is it a mistake or standard procedure to lit the landing lights only on very short final?" Tags="&lt;landing&gt;&lt;easa-regulations&gt;&lt;aircraft-external-lights&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27579" PostTypeId="2" ParentId="27576" CreationDate="2016-05-17T11:09:55.007" Score="15" Body="&lt;p&gt;The reason An 225 has only two nose landing gears (for a total of four wheels) is that it was developed from An 124 Ruslan, which had pretty much the same arrangement. This works during normal operations as the MLG take up most of the load. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, for loading/unloading, the wheels are not loaded- the nose landing gear is folded, while a support strut comes out, which provides the necessary support and load carrying capacity, as shown below (thanks to @Federico for finding the image).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/36uFk.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/36uFk.jpg&quot; alt=&quot;Strut&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.airliners.net/photo/Antonov-Design-Bureau/Antonov-An-225-Mriya/1802921/L/&quot; rel=&quot;noreferrer&quot;&gt;airliners.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this image, you can clearly see that the NLG is folded and the weight is supported by the struts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0h5uG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0h5uG.jpg&quot; alt=&quot;AN 225&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://au.news.yahoo.com/thewest/wa/a/31582963/take-a-tour-of-the-world-s-biggest-plane-an225/&quot; rel=&quot;noreferrer&quot;&gt;news.yahoo.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="9731" LastEditDate="2016-05-17T11:33:44.300" LastActivityDate="2016-05-17T11:33:44.300" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27580" PostTypeId="2" ParentId="27577" CreationDate="2016-05-17T14:27:50.130" Score="6" Body="&lt;p&gt;IATA themselves &lt;a href=&quot;http://www.iata.org/services/Pages/codes.aspx&quot; rel=&quot;noreferrer&quot;&gt;say it's a three-letter code&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Airlines and CRSs [computer reservations systems] may request the&#xA;  assignment of a unique three-letter code to identify an airport&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://www.unece.org/fileadmin/DAM/cefact/locode/unlocode_manual.pdf&quot; rel=&quot;noreferrer&quot;&gt;UN trade locations coding&lt;/a&gt; also says the same thing:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;when a three-letter code is used alone to indicate a location, it&#xA;  designates the name of an airport or location as adopted by IATA&#xA;  (whose code only has three letters)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to Wikipedia, IATA has several &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Air_Transport_Association_code&quot; rel=&quot;noreferrer&quot;&gt;different types of code&lt;/a&gt; that can be from one to four characters, but airport codes specifically are always three based on all the sources I mentioned.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-17T14:27:50.130" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27581" PostTypeId="2" ParentId="27574" CreationDate="2016-05-17T15:08:21.273" Score="0" Body="&lt;p&gt;As with anything you should refer to &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_manual&quot; rel=&quot;nofollow&quot;&gt;your POH for the specific aircraft&lt;/a&gt; as it often covers what you should do in this very case. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example the &lt;a href=&quot;http://takeflightsandiego.com/assets/documents/1980%20PA32-301%20POH.pdf&quot; rel=&quot;nofollow&quot;&gt;POH for the Piper Saratoga states&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4.39 Turbulent Air Operation&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;In keeping with good operating practice used in all aircraft it is recommended that wen turbulent air is encountered or expected, the airspeed is reduced to maneuvering speed to reduce the structural loads caused by gusts and to allow for inadvertent speed build-ups which may occur as a result of turbulence or of distractions caused by the conditions. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Of course this is not terribly specific as to what turbulence is but its safe to say that if you feel you are going to be thrown around to the point you will begin to see speed build ups as a result of the conditions you should reduce your speed to Va. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly the &lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow&quot;&gt;POH for the 172 states (P. 4-3)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Turbulent Air Penetration Speed:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;2300 Lbs ......... 97 KIAS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1950 Lbs ......... 89 KIAS&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;1600 Lbs ......... 80 KIAS&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Cessna seems to base it on load while Piper just advises a slow down to Va which is interesting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should also not be in the yellow arc (what ever it may be) in rough air, that is the &quot;smooth air operating range&quot; or &quot;caution range&quot;. Basically the advised &quot;slow down&quot; is to give you a buffer area so you can inadvertently speed up and not enter the caution area or come close to Vne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how much, I would say you should slow down in consistent turbulence. A single bump may just be you catching a thermal or crossing a mountain ridge etc. Turbulent air tends to persist the bumps as you move through it in which case I would slow down.    &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Speaking from personal experience I generally reduce speed when the ride gets &quot;choppy&quot; (its hard to say objectively what that is). This is somewhat a personal preference as well as for safety. The interesting thing to note is that when doing approaches in gusty conditions you may want to add speed to your approach speed.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-05-17T15:17:48.397" LastActivityDate="2016-05-17T15:17:48.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27582" PostTypeId="2" ParentId="27576" CreationDate="2016-05-17T15:21:11.290" Score="2" Body="&lt;p&gt;When an aircraft lands, the nose wheel remains elevated, and the main wheels touch down first. This results in a considerable impact on the runway as all of the weight of the aircraft hits the ground. In order to minimise the impact, and prevent damage to the runway, larger aircraft tend to have multiple bogeys on the main wheels to distribute the weight over a larger surface area.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the sheer size, and unique mission of the An-225, it features a number of wheels in order to maximise the weight distribution on the runway surface, allowing it to carry a greater weight, and operate from smaller airports with weaker runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The nosewheel does not suffer from this problem, as the landing impact is much softer due to the main wheels taking most of the weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interesting aside: The A320 can be purchased in both a single-pair and dual-pair main wheel configuration. So far, Indian Airlines (now part of Air India) are the only airline to operate the dual-pair main-wheeled A320, as the standard of runways is not as good in India, and therefore they can serve airports they otherwise wouldnt be able to do.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0n8vd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0n8vd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1720" LastEditorUserId="1720" LastEditDate="2016-05-17T18:47:36.303" LastActivityDate="2016-05-17T18:47:36.303" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27583" PostTypeId="2" ParentId="27574" CreationDate="2016-05-17T16:02:37.860" Score="3" Body="&lt;p&gt;To help you understand this, I feel like we should discuss how Va is determined.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=93e9c32bb8280fa7ba049f42dc60af23&amp;amp;mc=true&amp;amp;node=se14.1.23_1337&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 23.337 Limit maneuvering load factors.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) The positive limit maneuvering load factor n may not be less than—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) 2.1 + (24,000 ÷ (W + 10,000)) for normal and commuter category&#xA;  airplanes, where W = design maximum takeoff weight, except that n need&#xA;  not be more than 3.8;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) 4.4 for utility category airplanes; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) 6.0 for acrobatic category airplanes.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) The negative limit maneuvering load factor may not be less than—&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) 0.4 times the positive load factor for the normal utility and&#xA;  commuter categories; or&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) 0.5 times the positive load factor for the acrobatic category.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Maneuvering load factors lower than those specified in this&#xA;  section may be used if the airplane has design features that make it&#xA;  impossible to exceed these values in flight.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Based on that regulation, the light single-engine aircraft I've flown have a &lt;strong&gt;+3.8/-1.52 load factor limit in normal category&lt;/strong&gt; loading.  The aircraft is designed to structurally handle those load factors up to max gross weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A pilot could exceed those limits by making abrupt control inputs or &quot;pulling G's&quot; because by pitching up abruptly, for example, the pilot is increasing the angle of attack and accelerating the aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At speeds above Va, the wings are capable of producing enough force to damage the structure with positive or negative loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a V-G diagram (&lt;a href=&quot;http://www.dviaviation.com/image/51953489_scaled_616x408.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/CJMWm.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CJMWm.png&quot; alt=&quot;V-G Diagram&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The curved line represents the load factor at which the aircraft will stall at a given indicated airspeed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Va is the speed at which the aircraft would reach its maximum positive load factor limit at the same time it would experience an aerodynamic stall.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An angle of attack less than or greater than the critical angle of attack will cause the wing to generate less lift than it would at the critical angle of attack.  Therefore, the stall point is used to determine where the maximum load factor would occur for a given speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maneuvering speed, as you can see by the chart, has no safety buffer above it, which is why Dave's answer has some details about inadvertently increasing speed.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flying &lt;em&gt;below maneuvering speed&lt;/em&gt; would be a better guideline to follow if you feel that there is are hazardous levels of turbulence.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say you are flying well below Va, and you are hit by a strong vertical gust.  The vertical, upward, gust will increase the angle of attack by momentarily changing the relative wind, and therefore increase lift.  If that change in angle of attack exceeds the critical angle of attack, then the aircraft will aerodynamically stall rather than continue to produce greater lift. In that case, the stalled condition would protect the structure of the aircraft by acting as a limit on structure loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Now to answer your specific question:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is unlikely that severe turbulence will come as a surprise during flight in a small single-engine aircraft.  I have never personally experienced turbulence where I felt the need to decrease my speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a judgement call that needs to be made by the PIC, and I would slow down whenever I am experiencing consistent turbulence that is causing me to physically perceive unusually high G-forces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If a pilot is in that scenario, there has likely been a poor go/no go decision regarding the flight.  If you need a quantifier, &quot;severe turbulence&quot; would be the classification for which this matters.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have experienced moderate to severe turbulence in flight, but those were attitude altering gusts; the load factors imposed were not near limits.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-18T05:11:40.007" LastActivityDate="2016-05-18T05:11:40.007" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27584" PostTypeId="1" AcceptedAnswerId="27592" CreationDate="2016-05-17T18:34:29.650" Score="9" ViewCount="1123" Body="&lt;p&gt;Why is a ski-shaped deck used on an aircraft carrier for take off?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft needs a particular lift for a particular weight, how does ski assist in take off?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="3201" LastEditDate="2016-05-18T07:27:57.340" LastActivityDate="2017-04-12T15:44:31.963" Title="How does the ski shape of an aircraft carrier deck help for take off?" Tags="&lt;aircraft-carrier&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27585" PostTypeId="2" ParentId="27574" CreationDate="2016-05-17T19:15:43.427" Score="1" Body="&lt;p&gt;If the load factor from the next vertical gust is likely to exceed the maximum load factor of your aircraft it is time to slow down. Now you might wonder how to know the strength of the next gust. If flying in gusty air is &lt;strong&gt;really&lt;/strong&gt; uncomfortable, better slow down. It's not that you are about to break the aircraft, but being kicked about in the cockpit will severely restrict your flying skills. Flying more slowly is safer because you stay in control. Lower speed will increase the angle of attack change from the gust, but the lower dynamic pressure will reduce overall loads. Also, the lower speed translates into a less steep gust load onset ramp, which also makes flying at lower speed more comfortable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Regarding the duration: Slow down immediately if only one gust feels like it exceeds your maximum load factor. Yes, there is a structural safety limit of 50%, and it will take thousands of gusts at the rated limit load to exceed the fatigue limit, but with gusts I recommend to play it safe. Note that the increase in safety comes mainly from avoiding piloting errors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My worst experience was in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Diamond_DA20&quot; rel=&quot;nofollow&quot;&gt;Katana&lt;/a&gt; over the Arkansas River valley. Coming from Oklahoma, the cloud cover under me increased and I was forced to continue below the clouds, flying VFR only. Below the clouds I was literally thrown around by the worst gusts I have ever experienced. To make the experience tolerable I flew more slowly than usual, but not much - I wanted not to stay too long in this kind of weather.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Gerhard_Waibel_(engineer)&quot; rel=&quot;nofollow&quot;&gt;Gerhard Waibel&lt;/a&gt; once told me he was invited to fly with &lt;a href=&quot;https://en.wikipedia.org/wiki/Karl_Striedieck&quot; rel=&quot;nofollow&quot;&gt;Karl Striedieck&lt;/a&gt; along the Appalachians. Now you need to know that both flew an &lt;a href=&quot;https://en.wikipedia.org/wiki/Schleicher_ASW_20&quot; rel=&quot;nofollow&quot;&gt;ASW-20&lt;/a&gt;, a glider which Gerhard had designed. And he knows that he built in reserves! Karl's style of flying was repeatedly overloading the airframe beyond the design limit, but he never slowed down. Gerhard, certainly no wussy, said that he was seriously concerned that Karl would break the airplane, but he never did. He will turn 80 next year.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-18T19:47:10.293" LastActivityDate="2016-05-18T19:47:10.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27586" PostTypeId="2" ParentId="15042" CreationDate="2016-05-17T19:38:09.450" Score="1" Body="&lt;p&gt;With the 737-900 tipping is a real issue. IMHO the lack of incidents is down to luck more than anything else.&#xA;This was an unloading incident. The rampers can be seen removing bags (weight) from the front pit. Added to this, normal unloading sees all of the 1st class passengers leaving the aircraft followed by economy passengers row by row, front to back. This means at some point all of the passengers in front of the main undercarrage are off the aircraft while all those behind remain on board. &#xA;The extra length of the 900 means that the combined weight of the remaining passengers is further back than that of a 700 or 800. When this is added to an empty front cargo/baggage pit tipping is a very real possibility.&#xA;The Airlines and Boeing know this problem exists with the 900 and are taking it seriously enough to develop tailstands similar to those used by cargo operators on their 747 freighters.&lt;/p&gt;&#xA;" OwnerUserId="14948" LastActivityDate="2016-05-17T19:38:09.450" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27587" PostTypeId="1" AcceptedAnswerId="27591" CreationDate="2016-05-17T19:56:07.187" Score="6" ViewCount="8657" Body="&lt;p&gt;It seems that there is no XXX IATA code: from &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_airports_by_IATA_code:_X&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt;, XVL (Vinh Long, Vietnam) is followed by XYA (Yandina, Solomon Islands). There is a &lt;a href=&quot;http://airport-codes.wanderbat.com/l/14254/Mena-AR-Mena-Intermountain-Municipal&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt; claiming that XXX used to refer to Mena Intermountain Municipal Airport, but from &lt;a href=&quot;https://en.wikipedia.org/wiki/Mena_Intermountain_Municipal_Airport&quot; rel=&quot;nofollow&quot;&gt;Wikipedia&lt;/a&gt; this place seems (rather strangely) to have no IATA code at all (and a &lt;a href=&quot;http://www.gcmap.com/airport/KMEZ&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt; for this claim is given).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the reasons for not having the XXX IATA code? Is this a reserved combination? Has it belonged to the Mena Airport in the past, and if so, why has it been deregistered on October 21, 2014, as the source claims?&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="9276" LastEditDate="2016-05-18T09:41:29.877" LastActivityDate="2016-05-18T09:41:29.877" Title="Why there is no airport IATA code XXX?" Tags="&lt;iata&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27588" PostTypeId="5" CreationDate="2016-05-17T19:58:46.750" Score="0" Body="" OwnerUserId="-1" LastEditorUserId="-1" LastEditDate="2016-05-17T19:58:46.750" LastActivityDate="2016-05-17T19:58:46.750" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27589" PostTypeId="4" CreationDate="2016-05-17T19:58:46.750" Score="0" Body="International Air Transport Association (IATA) is the trade association of the world’s airlines. IATA assigns three letter codes (used mainly by passenger booking services) for airports." OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-05-17T21:02:11.770" LastActivityDate="2016-05-17T21:02:11.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27590" PostTypeId="1" AcceptedAnswerId="27594" CreationDate="2016-05-17T20:42:05.333" Score="11" ViewCount="3717" Body="&lt;p&gt;Can small airplanes, such as a Cessna 172, dump fuel during flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My understanding is that large commercial passenger aircraft often have the capability to dump fuel during flight, as can many military aircraft.  However, is that capability available for small 2 or 4 seat planes?  How big does a plane need to be before a fuel dump capability becomes useful?&lt;/p&gt;&#xA;" OwnerUserId="14949" LastActivityDate="2016-05-21T07:06:57.387" Title="Can small airplanes dump fuel during flight?" Tags="&lt;fuel-dumping&gt;" AnswerCount="7" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27591" PostTypeId="2" ParentId="27587" CreationDate="2016-05-17T20:43:00.567" Score="22" Body="&lt;p&gt;It looks to me like the &lt;a href=&quot;http://airport-codes.wanderbat.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source site&lt;/a&gt; you quoted is unreliable or at least not current, e.g. it gives results for codes QQQ and ZZZ too, but they &lt;a href=&quot;http://www.iata.org/publications/Pages/code-search.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;haven't been assigned by IATA&lt;/a&gt;. The actual IATA code for &lt;a href=&quot;http://airnav.com/airport/KMEZ&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mena (ICAO: KMEZ)&lt;/a&gt; seems to be MZX.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, there's no particular reason why &lt;a href=&quot;https://aviation.stackexchange.com/q/16667/62&quot;&gt;XXX&lt;/a&gt;, ZZZ or any other specific combination should be assigned; they just &lt;a href=&quot;https://aviation.stackexchange.com/q/21395/62&quot;&gt;haven't been used yet&lt;/a&gt;. There's also no reason why IATA should assign a code to every airport: the US alone &lt;a href=&quot;http://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/html/table_01_03.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;has over 5,000 public airports&lt;/a&gt; but only 500 or so have air carrier service.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2016-05-17T20:43:00.567" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27592" PostTypeId="2" ParentId="27584" CreationDate="2016-05-17T21:09:44.337" Score="11" Body="&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_deck#Ski-jump_ramp&quot;&gt;The Ski jump was originally used by the UK Royal Navy&lt;/a&gt; to assist Harriers in getting airborne.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Harrier cannot take-off vertically when fully loaded.  &lt;a href=&quot;https://en.wikipedia.org/wiki/Harrier_Jump_Jet#Specifications&quot;&gt;In all models, the thrust is lower than the maximum weight&lt;/a&gt;.  Therefore, they need to do a &quot;short take-off&quot; where the thrust nozzles are angled rearwards to provide thrust, then partially angled downwards as speed is gained to produce enough lift from the wings, and thrust angled downwards, to climb away.  Watch the nozzles closely at about 17 and 36 seconds in &lt;a href=&quot;https://www.youtube.com/watch?v=nLn-Nt4GCbU&quot;&gt;this video&lt;/a&gt;.  Try not to watch the poor chaps forehead too closely at 20 seconds.  Also watch &lt;a href=&quot;https://www.youtube.com/watch?v=KhnytihkJHs&quot;&gt;this video&lt;/a&gt;.  At about 16 seconds, you can see the pilots left hand pull back on the &lt;a href=&quot;https://i.ytimg.com/vi/Cd8u-9HjL04/maxresdefault.jpg&quot;&gt;nozzle angle lever&lt;/a&gt; as he passes the end of the deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now imagine a flat deck on an aircraft carrier.  Operations must be able to carry on in rough seas.  You accelerate down the deck and fly off the end, just as the deck dips downwards as the carrier rides a large wave.  You are pointed straight at the sea.  In order to avoid flying into the sea, you need to climb, which means pulling G and a lot of power at low speed which the Harrier just didn't have.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now consider the ski jump.  There are two effects.  &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The jump is angled so that even in the worst seas in which operations will continue, the bow pitching down will not point an aircaft leaving the end of the jump towards the sea.  The aircraft will always be pitched upwards.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Imagine driving a fast car up the jump and off the end.  It will be thrown up and forward in a &lt;a href=&quot;https://en.wikipedia.org/wiki/Parabola&quot;&gt;parabola&lt;/a&gt;.  Even a car, which cannot fly, will be pointing up for a few seconds, then level for few seconds before falling into the sea.  But instead of a car, you are driving a jet which can fly and has thrust. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The aircraft will angle the nozzles rearwards for maximum acceleration until it leaves the jump. The wings are now generating significant lift, let's say 50% of that required to climb away.  As you leave the end of the jump, you angle the nozzles downwards so that you have the momentum of the aircraft and some rearward thrust maintaining lift on the wings whilst adding lift from the thrust vector having a downward component.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those seconds of pointing up, then level, enable the aircraft to continue to accelerate until all of the lift required can be gained from the wing when the nozzles can now be angled rearward again to continue the acceleration. Take-off speed is therefore reduced and take-off distance is about halved meaning smaller, cheaper carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's how Harriers do it.  I imagine it's the same story for any other VSTOL aircraft.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-05-18T07:22:06.250" LastActivityDate="2016-05-18T07:22:06.250" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27593" PostTypeId="2" ParentId="15042" CreationDate="2016-05-17T21:10:03.327" Score="8" Body="&lt;p&gt;One thing these answers miss is that fact that there have actually been a handful of tail tip incidents on the 737-900. Since it's happened, then the answer is obviously: yes, it's possible. See, for instance &lt;a href=&quot;https://www.youtube.com/watch?v=JLWxD0gY__A&quot; rel=&quot;noreferrer&quot;&gt;this video&lt;/a&gt; of a Delta 737 tipping. There was apparently &lt;a href=&quot;http://www.luchtzak.be/miscellaneous/incidents/ukrainian-international-airlines-boeing-737-900-tail-tipped/&quot; rel=&quot;noreferrer&quot;&gt;just one at TLV&lt;/a&gt;. United &lt;a href=&quot;http://derbosoft.proboards.com/thread/19319/boeing-737-900er-tail-issues&quot; rel=&quot;noreferrer&quot;&gt;warned its pilots&lt;/a&gt; about the situation and put in place some procedures to better load cargo and ensure bags are quickly removed from the rear cargo bin before allowing forward passengers off. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To help prevent this, United &lt;a href=&quot;http://aviationweek.com/awincommercial/united-building-its-own-tail-stands-737-900s&quot; rel=&quot;noreferrer&quot;&gt;is rolling out tail stands&lt;/a&gt; for these aircraft. &lt;a href=&quot;https://www.reddit.com/r/aviation/comments/3vwzfp/this_is_how_we_prevent_tilting_of_a_737900/&quot; rel=&quot;noreferrer&quot;&gt;Delta has used stands too&lt;/a&gt;. &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/6614930/&quot; rel=&quot;noreferrer&quot;&gt;This discussion&lt;/a&gt; at airliners.net has more from some employees who've used them. &lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2016-05-17T21:10:03.327" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27594" PostTypeId="2" ParentId="27590" CreationDate="2016-05-17T22:13:18.893" Score="11" Body="&lt;p&gt;The short answer is, no, generally only large aircraft have purpose-built fuel dumping systems. Such a system may be helpful in reducing aircraft gross weight to a safe landing weight in the case of a precautionary landing. The approved landing weight of smaller aircraft, such as the C172, is generally the same as the approved takeoff weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The longer answer is, yes, it would be possible to &quot;dump&quot; fuel from an aircraft such as a C172, though not by means of a purpose built mechanism. The &quot;dumping&quot; would be more of a slow to moderately fast drain, depending on the means used.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I wanted to drain the fuel from one of the wing tanks in a C172 while in flight I could use a pen, screw or other such device to drain fuel from the wing tank sump. A faster dumping/draining method—though requiring considerably more work—would be to unscrew and remove the fuel drain valve, thereby releasing all the fuel in the wing. Obviously, this later method would hamper the possibility of draining only a portion of the fuel from the wing tank.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/jZkOM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/jZkOM.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I cannot think of any reason why I would want to drain the fuel in flight apart from reducing the risk of fire in the event of an emergency landing. And in that case, my prefered method of reducing the risk of a post-landing fire would be to concentrate my efforts on the landing, not on eliminating a fuel source.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, I prefer to have more rather than less fuel in the tanks when I fly.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastActivityDate="2016-05-17T22:13:18.893" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27595" PostTypeId="2" ParentId="27590" CreationDate="2016-05-17T22:50:38.773" Score="5" Body="&lt;p&gt;As Jonathan mentions these systems are typically not found on light aircraft as there is little need for them but in some cases the design of the plane may allow for it. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-32R&quot; rel=&quot;nofollow noreferrer&quot;&gt;Piper Saratoga&lt;/a&gt; has has an in cabin fuel drain switch that drains fuel from a center drain at a low point on the fuselage. This is intended for expelling water from the system but can in theory be used to dump fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Wkg8x.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Wkg8x.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://takeflightsandiego.com/assets/documents/1980%20PA32-301%20POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Other aircraft may have similar systems as well. The small/older cherokees however do not contain such a system. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-17T22:50:38.773" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27598" PostTypeId="2" ParentId="15042" CreationDate="2016-05-18T04:00:16.450" Score="1" Body="&lt;p&gt;The reason for this possibility is the way the tricycle landing gear works. In a classic design, the line from the main wheels to the centre of mass (CM) (projected on the vertical plane of symmetry) comes at an angle of 15° forward from vertical. This is only slightly more than the angle to which the aircraft rotates during takeoff. The whole point of this arrangement is that the aircraft could rotate with normal pitch input, and similarly be controllable on landing when touching down on main wheels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With the CM slightly aft for whatever reason, the airplane will not need much force to tip over, and may remain stable in such position.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the aircraft with tail mounted engines are more prone to this phenomenon. Most of their payload is located forward of CM (because of the heavy engines on the back), so invariably they have very aft CM when empty. Tu-154 was known to tip over by hand force when empty (typically, when a mechanic was doing some service on the tail).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IL-62 (one of the few airplanes with 4 tail engines) has a special tail wheel to prevent this.&#xA;&lt;a href=&quot;http://cdn-www.airliners.net/aviation-photos/middle/6/3/9/0623936.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Il-62 support wheel http://cdn-www.airliners.net/aviation-photos/middle/6/3/9/0623936.jpg&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.airliners.net/photo/Russia-State-Transport/Ilyushin-Il-62M/0623936/L/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;P.S. You can find a galore of tipped aircraft of all kinds in &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/print.main?id=6562953&quot; rel=&quot;nofollow noreferrer&quot;&gt;this thread&lt;/a&gt; (scroll to the middle).&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-05-18T04:00:16.450" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27599" PostTypeId="2" ParentId="27578" CreationDate="2016-05-18T05:58:01.470" Score="7" Body="&lt;p&gt;It is not an ICAO &lt;em&gt;requirement&lt;/em&gt; to operate landing lights whenever you are below 10,000 FT. The mandatory aircraft lights you will see in regulations is strobe lights, nav lights and anti collision beacon lights.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is standard operating procedure at several airlines to only turn on the landing lights when a landing clearance is received by air traffic control. This is most likely what you have observed. The landing clearance is usually given at very short final, and so crews will turn on the landing lights on very short final (unless you are in FAA territory, where multiple aircraft can be cleared to land on the same runway at the same time ...)&lt;/p&gt;&#xA;" OwnerUserId="14957" LastEditorUserId="5517" LastEditDate="2016-05-18T12:25:22.370" LastActivityDate="2016-05-18T12:25:22.370" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27600" PostTypeId="2" ParentId="21522" CreationDate="2016-05-18T06:12:45.040" Score="2" Body="&lt;p&gt;ICAO three-letter codes are always unique. The official source, ICAO Document 8585, says the following:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;1.2 The same designator will not be registered for more than one aircraft operating agency, aeronautical authority or service.&lt;/p&gt;&#xA;&lt;p&gt;1.3 No more than one three-letter or telephony designator will be registered for each aircraft operating agency, aeronautical authority or services.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;In your example, Tiger Airways Singapore only exists as a single airline in document 8585. The fact that they have an Australian division does not mean that it is a separate aircraft operator, and thus no separate ICAO code can be assigned.&lt;/p&gt;&#xA;&lt;p&gt;You can find more rules regarding ICAO identification codes, including a complete list of every ICAO code in the world, in doc 8585: &lt;a href=&quot;http://dcaa.trafikstyrelsen.dk:8000/icaodocs/Doc%208585/DOC%208585,%20Edition%20no%20149.PDF&quot; rel=&quot;nofollow noreferrer&quot;&gt;http://dcaa.trafikstyrelsen.dk:8000/icaodocs/Doc%208585/DOC%208585,%20Edition%20no%20149.PDF&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;Interestingly, British Airways seem to contradict the above rules with their seasonal &amp;quot;Santa&amp;quot; flights. Around Christmas, certain British Airways flights will operate with the XMS ICAO code (radio callsign &amp;quot;Santa&amp;quot;), instead of the usual BAW ICAO code (radio callsign &amp;quot;Speedbird&amp;quot;).&#xA;In ICAO doc 8585, the XMS code is registered to &amp;quot;British Airways Santa&amp;quot;, which I very much doubt is the name of a real company, so it does seem there are ways around the rules quoted above.&lt;/p&gt;&#xA;" OwnerUserId="14957" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-18T20:11:02.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27601" PostTypeId="2" ParentId="27563" CreationDate="2016-05-18T06:23:43.393" Score="1" Body="&lt;p&gt;Where ICAO rules apply (e.g. most of the world), broadcasting a change in QNH to the entire frequency is not sufficient. The QNH is considered (for good reason) to be safety critical information, and so each aircrew most positively acknowledge that they have correctly received it. This means informing each aircraft on the frequency of the new QNH, and wait for them to read back.&#xA;I'm sure this is not always actually done, but it is what the rules say.&lt;/p&gt;&#xA;&lt;p&gt;Reference: ICAO document 9432, 2.8.3.5:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;The following information shall always be read back:&lt;/p&gt;&#xA;&lt;p&gt;[...]&lt;/p&gt;&#xA;&lt;p&gt;c) runway-in-use, &lt;strong&gt;altimeter settings&lt;/strong&gt;, SSR codes, level instructions, heading and speed instructions and,&#xA;whether issued by the controller or contained in ATIS broadcasts, transition levels.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="14957" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-18T06:23:43.393" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27602" PostTypeId="2" ParentId="27234" CreationDate="2016-05-18T06:38:23.183" Score="2" Body="&lt;p&gt;Continuous descent operations do not warrant a change in separation minima. The same separation minima (wake turbulence, radar minima, lateral, horizontal and vertical minima) apply at CDA airports as they do at all other airports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer 2, 4 and 5 at the same time: continuous descent approach means that an aicraft descending from cruise level (typically 10-11 km.) to the final approach procedure (typically about 1000 metres) will do so in one continuous motion - e.g. without levelling out and maintaining a certain intermediate level along the way.&#xA;Although it is possible, and widely utilised, crews are not required to use idle engine thrust for the descend. It may well be the case that an aircraft is required by air traffic control to maintain a certain speed during descend, in order to establish and maintain the separation requirements mentioned above. As such, you can see CDA operations where aircraft apply thrust during descend, but where the descend is still conducted as one continuous motion.&#xA;On the final approach, usually starting at an altitude of about 1000 metres, 20 or-so km. from the airport, there is no difference between CDA and non-CDA operations. Aircraft will fly completely normally, using engine thrust and lift augmentation devices (flaps, slats) to maintain an appropriate airspeed (actually, angle of attack) so that the aircraft descends at the correct rate to hit the runway. For a normal jet aircraft, it is &lt;em&gt;not&lt;/em&gt; possible to fly the final 20-or-so km. of the approach with idle thrust - it simply wouldn't make it to the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When talking about track miles, I will assume you are talking about the distane from the top of descend (TOD) until the runway threshold (THR). For an average jet airlines, descending from a level of 10-11 km., it will take somewhere between 100 and 120 nautical miles of distance to get from TOD to runway THR. For non-CDA airports, this distance will generally be longer, because the descend has to be initiated sooner, but you will also find examples where there is almost no difference.&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-05-18T06:38:23.183" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27603" PostTypeId="1" CreationDate="2016-05-18T11:37:25.913" Score="43" ViewCount="85348" Body="&lt;p&gt;If an airliner is flying at approximately 500-600mph, it seems to me that there would need to be a significant adjustment for altitude so as to not fly off into space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Bedford_Level_experiment&quot;&gt;says that there's an 8 inch drop for every mile&lt;/a&gt; because of the Earth's curvature. But, I've never heard of any airliner adjusting for the curvature. Also, shouldn't aircraft have to adjust somehow for the &lt;a href=&quot;https://en.wikipedia.org/wiki/Earth%27s_rotation#Angular_speed&quot;&gt;Earth's rotation&lt;/a&gt; because it varies depending on the latitude?&lt;/p&gt;&#xA;" OwnerUserId="9105" LastEditorUserId="62" LastEditDate="2016-05-20T20:57:40.733" LastActivityDate="2020-03-25T20:10:04.997" Title="Do pilots adjust the aircraft's flight path to allow for the curvature of the Earth?" Tags="&lt;altitude&gt;" AnswerCount="18" CommentCount="4" FavoriteCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27604" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T11:50:28.393" Score="75" Body="&lt;p&gt;There is no adjustment needed as the aircraft will naturally follow the curvature of the earth without any input from the pilot. This is because the aircraft flies through the atmosphere which also follows the curvature of the earth.&lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-05-18T11:50:28.393" CommentCount="17" ContentLicense="CC BY-SA 3.0" />
  <row Id="27605" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T11:57:13.607" Score="30" Body="&lt;p&gt;There isn't an adjustment for altitude. An aircraft flying level at a given altitude and trimmed for level flight will stay at that altitude. That means the flight path will have a gentle nose-down curve (looking from far away from the earth) as the direction of down (towards the centre of the earth) changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Think about the gravitational potential energy of the aircraft. To climb (which is actually flying in a straight line when you consider the curvature of the earth), the aircraft has to gain energy. In a level flight attitude, it doesn't gain any energy, so it will stay at the same altitude. A path that doesn't gain or lose altitude is an ellipse that goes around the earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another way of thinking about it is to consider how &quot;down&quot; changes as the aircraft travels. The weight of the aircraft always acts towards the centre of the earth, and is matched (in level flight) by the lift of the wings. Imagine if you had a model aircraft suspended on a piece of string, dangled from your hand. If you hold the string and carry the model a quarter of the way around the earth, the bottom of the model will still point down (towards the centre of the earth). The model has rotated 90 degrees, without you having to rotate it by hand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you trim for level flight, you do so by finding the pitch attitude where your speed and altitude remain constant (or at least stable: atmospheric conditions might make them fluctuate a lot). That attitude might be a touch more nose-down than it would be if the earth were flat, but it's imperceptible.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="998" LastEditDate="2016-05-18T17:59:24.777" LastActivityDate="2016-05-18T17:59:24.777" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27606" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T12:01:46.700" Score="83" Body="&lt;p&gt;Aircraft altitude is measured (inferred) by atmospheric pressure. The aircraft is usually flown at an altitude that maintains constant ambient pressure (by pilot or autopilot, as the case may be). Changes in local barometric pressure (provided by air traffic control) are used to recalibrate the aircraft altimeter.  As long as the aircraft is flown at a constant ambient pressure (hence constant altitude), it will be following the earth's curvature (as the atmosphere is attached to the spherical earth and has same properties at same distance from the center, in an ideal case) as the altitude is measured from the surface, which is curved, and not a plane.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2019-01-17T16:36:46.727" LastActivityDate="2019-01-17T16:36:46.727" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27607" PostTypeId="1" AcceptedAnswerId="27614" CreationDate="2016-05-18T12:22:10.133" Score="8" ViewCount="971" Body="&lt;p&gt;The climb-out for one of the runways at my local aerodrome is over a residential area, with fields to the left. My instructor has had a bee in his bonnet lately about engine failure after take-off if the take-off run is longer than it should be (e.g. after a touch-and-go). He's started encouraging all of us to perform constant-aspect climb-out into the circuit, where we start the turn onto the crosswind leg at the aerodrome boundary regardless of height, and keep the runway end at the same declination in our field of view as the turn progresses. This means we point towards the fields much earlier on, but it hurts the climb performance to do it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although I can see the wisdom of being ready for EFATO, I'm concerned about practising a non-standard circuit which contravenes the Noise Abatement Procedure. (The NAP forbids turns below 500 ft, although it is overridden by measures to ensure flight safety.) When I come to do my PPL skills test, would this unusual circuit be acceptable, or will I have to fly a standard circuit with a straight climb-out, turning onto base at 500 ft? I'm in the UK and studying towards an EASA PPL(A).&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-05-18T15:40:56.887" Title="Will I fail a skills test for doing a constant-aspect climb-out?" Tags="&lt;flight-training&gt;&lt;easa&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27608" PostTypeId="2" ParentId="27590" CreationDate="2016-05-18T12:24:09.117" Score="5" Body="&lt;p&gt;On some small aircraft it is possible to dump a small portion of fuel by mishandling the fuel system. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On certain models of Cessna 310, 401, 402, 414, 421 and similar aircraft, the auxiliary tanks feed return fuel back to the main tanks. Normal procedure is to burn down the mains before switching to the auxiliary tanks. If the mains are full the return fuel from the auxiliary tanks will overflow the mains and be vented overboard. Wing locker tanks were pumped directly into the mains and would also cause venting overboard if activated too early.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One time I was asked to take a Cessna 310 to a very short runway to pick up 5 passengers and their luggage. The aircraft had accidentally been fuelled to 1,200 lbs. when only only 600 lbs was needed to complete the trip. The extra 600 lbs. of fuel would have made the aircraft over weight &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Shortly after take off I switched to the auxiliary tanks and also activated the wing locker tanks. This resulted in the main tanks becoming over filled and about 400 lbs of fuel was both consumed and also vented overboard during the 1 hour flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;While this was not an actual example of fuel dumping, it had the same effect, and allowed me to depart a short runway with a full load of passengers and baggage while not being overweight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2bTt5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2bTt5.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="1467" LastEditDate="2016-05-19T06:49:31.333" LastActivityDate="2016-05-19T06:49:31.333" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27610" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T14:14:38.977" Score="22" Body="&lt;p&gt;This is more of a physics question rather than an aviation question. While other answers have addressed the question from the aerodynamics point of view, let me try answering it from a physics perspective: &lt;strong&gt;frame of reference&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;h2&gt;Frame: where are you going?&lt;/h2&gt;&#xA;&lt;p&gt;How do you know an object is moving? The answer is you don't - there is nothing like a &amp;quot;fixed absolute coordinate in space&amp;quot;. Speed is measured by referencing another object. If you think of it, every time we mention an object's speed, we always mean it's speed relative to something. The car's speed is 50mph relative to the ground below it, although we seldom say it explicitly in our daily conversations.&lt;/p&gt;&#xA;&lt;h2&gt;Curvature of the Earth&lt;/h2&gt;&#xA;&lt;p&gt;Most of our daily experiences of motion are related to one of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Fundamental_interaction&quot; rel=&quot;noreferrer&quot;&gt;four fundamental forces of nature&lt;/a&gt;: &lt;strong&gt;gravity&lt;/strong&gt;. Gravity is spherical - if we pick a random point on the planet, the gravitational force should be the same as any other random point (let's assume the Earth is a perfect sphere for now).&lt;/p&gt;&#xA;&lt;p&gt;Consider me walking on the surface of the Earth. I would be unaware that the Earth is spinning without external reference points like stars and the sun. If the Earth stands still, I would walk just the same, because when I walk I am interacting with the ground below me, which is part of the Earth; I am not interacting with Saturn or any other planet.&lt;/p&gt;&#xA;&lt;h2&gt;How do planes fly?&lt;/h2&gt;&#xA;&lt;p&gt;Well, it happens that planes fly by interacting with the atmosphere. The atmosphere is affected by the Earth's gravity like the ground - the &lt;em&gt;ground+atmosphere&lt;/em&gt; spins round and around together. Airplanes are not interacting with other stars or planets or satellites in any way - its engines produce thrust against the atmosphere (which moves together with the ground).&lt;/p&gt;&#xA;&lt;p&gt;You chose your frame of reference as an arbitrary point in space, which is why it leads to incorrect conclusions. If you are travelling on a train and you want to move around, you don't have to factor in how fast the train is moving - you are interacting with the train, not the rail which the train travels on. Otherwise, as the train moves forward following the curvature of the Earth, you will rise higher and higher in the cabin, eventually hitting the ceiling. You are following gravity, which is spherical. Same for planes.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-18T19:51:34.567" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27611" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T14:32:06.907" Score="3" Body="&lt;p&gt;An important flight instrument is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_instruments#Attitude_Indicator&quot; rel=&quot;nofollow noreferrer&quot;&gt;Attitude Indicator&lt;/a&gt;, which has an artificial horizon line.  This instrument tells the pilot if the wings are level and whether the nose is pointing above or below the horizon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Rather than &lt;em&gt;never&lt;/em&gt; taking the curvature of the earth into account, when a pilot is using this instrument to keep his flight level, he is actually &lt;em&gt;constantly&lt;/em&gt; adjusting for the curvature of the earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: The following link is to a question on how attitude indicators are kept accurate.  A particularly acrobatic flight might cause it to tumble and become useless until it is reset.  However it easily maintains accuracy during normal flights, including sustained turns.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/16376/how-are-attitude-indicators-kept-accurate&quot;&gt;How are attitude indicators kept accurate&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Short version: Yes, a gyroscope would have problems with earth curvature, but another part of this instrument constantly maintains a &quot;local down&quot; for the instrument.&lt;/p&gt;&#xA;" OwnerUserId="11598" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-05-19T13:46:30.807" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27612" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T15:00:57.603" Score="12" Body="&lt;p&gt;Is a plane fast enough to get to space? Well, unfortunately for space exploration, no, it isn’t. Let’s check with a few calculation.&lt;/p&gt;&#xA;&lt;h2&gt;Assumptions and definitions&lt;/h2&gt;&#xA;&lt;p&gt;First, let’s make an assumption: our plane &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; is flying in the void: there is no air slowing it down. Of course, this assumption is &lt;em&gt;very&lt;/em&gt; wrong, but we only care about speed here. Air friction only slows &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; down. So, if &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; doesn’t go into space without an atmosphere, it won’t either if we &lt;em&gt;add&lt;/em&gt; an atmosphere.&lt;/p&gt;&#xA;&lt;p&gt;Let’s consider a reference object &lt;em&gt;&lt;strong&gt;O&lt;/strong&gt;&lt;/em&gt; orbiting the Earth at the same altitude &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt; as our plane. Of course, we can neglect the mass of &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; and &lt;em&gt;&lt;strong&gt;O&lt;/strong&gt;&lt;/em&gt;, which is several orders of magnitude lesser than the mass of the Earth.&lt;/p&gt;&#xA;&lt;p&gt;Let &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; be the &lt;a href=&quot;https://en.wikipedia.org/wiki/Orbital_speed&quot; rel=&quot;noreferrer&quot;&gt;orbital speed&lt;/a&gt; of &lt;em&gt;&lt;strong&gt;O&lt;/strong&gt;&lt;/em&gt; and &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;P&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; be the speed of &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt;. If &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;P&lt;/sub&gt; &amp;gt; v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt;, then &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; will spiral away from Earth and end up in space. If, on the other hand, &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;P&lt;/sub&gt; &amp;lt; v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt;, then &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt; will spiral down until it crashes.&lt;/p&gt;&#xA;&lt;h2&gt;Computing &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt;&lt;/h2&gt;&#xA;&lt;p&gt;Because &lt;em&gt;&lt;strong&gt;O&lt;/strong&gt;&lt;/em&gt; is orbiting on a circular trajectory, &lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; and &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt; are correlated by the following formula:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; = √(&lt;em&gt;GM&lt;/em&gt;/&lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Where &lt;em&gt;G&lt;/em&gt; is the gravitational constant and &lt;em&gt;M&lt;/em&gt; the mass of the object we’re orbiting around.&lt;/p&gt;&#xA;&lt;p&gt;In our case, we are orbiting around the Earth and&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_gravitational_parameter&quot; rel=&quot;noreferrer&quot;&gt;&lt;em&gt;GM&lt;/em&gt; = 3.99×10&lt;sup&gt;14&lt;/sup&gt; m&lt;sup&gt;3&lt;/sup&gt;s&lt;sup&gt;-2&lt;/sup&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;By using the SI units and approximating 3.99 with 4, we end up with the following relation:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; = 2×10&lt;sup&gt;7&lt;/sup&gt; &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt;&lt;sup&gt;-1/2&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The radius of the Earth is included in &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt;, so we must add 6 371 km to go from altitude to &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt;. 6 371 km is actually two order of magnitude higher than any altitude you could fly at, so let’s round it to 6,400 km and be happy with it.&lt;/p&gt;&#xA;&lt;p&gt;So, in order to orbit at 6 400 km = 6 400 000 m from the center of Earth, we would need to go at&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt; = 2×10&lt;sup&gt;7&lt;/sup&gt; &lt;em&gt;&lt;strong&gt;r&lt;/strong&gt;&lt;/em&gt;&lt;sup&gt;-1/2&lt;/sup&gt; = 2×10&lt;sup&gt;7&lt;/sup&gt; (6 400 000)&lt;sup&gt;-1/2&lt;/sup&gt; m/s = 2×10&lt;sup&gt;7&lt;/sup&gt;/2530 m/s = 7.9×10&lt;sup&gt;3&lt;/sup&gt; m/s = 1.8×10&lt;sup&gt;4&lt;/sup&gt; mph&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;That’s the speed relative to the center of the Earth, not to its surface.&lt;/p&gt;&#xA;&lt;h2&gt;So, does our poorly modeled plane fly?&lt;/h2&gt;&#xA;&lt;p&gt;Our plane &lt;em&gt;&lt;strong&gt;P&lt;/strong&gt;&lt;/em&gt;, is flying at 600 mph relative to the surface. If we suppose we’re flying above the equator, we can reach a speed of 1600 mph relative to the center; that still is an order of magnitude below the speed we need to reach to orbit at such a low altitude.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;v&lt;sub&gt;P&lt;/sub&gt; &amp;lt;&amp;lt; v&lt;sub&gt;O&lt;/sub&gt;&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Our plane would crash. &lt;em&gt;Fast&lt;/em&gt;.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h2&gt;Thank goodness, planes are safer than that. But how come?&lt;/h2&gt;&#xA;&lt;p&gt;Well, as we’ve just seen, the speed of the plane is not what keeps it flying. But we made a very strong assumption in our opening section: we neglected the atmosphere.&lt;/p&gt;&#xA;&lt;p&gt;Air certainly slow our plane down. But we’ve also built it so that, when moving through air, our plane tends to go up thanks to &lt;a href=&quot;https://en.wikipedia.org/wiki/Lift_(force)&quot; rel=&quot;noreferrer&quot;&gt;lift&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;So we have two opposing effects, here: the plane isn’t going fast enough to escape the Earth attraction; but the lift pulls up the plane hard enough that it keeps flying. But lift depends, among other things, on the density of air around the plane: the higher the planes fly, the weaker lift is. So, all in all, the plane flies in a layer of air at the same pressure, which in turn follows approximately the surface of the Earth.&lt;/p&gt;&#xA;" OwnerUserId="13933" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-21T01:58:03.757" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27613" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T15:37:36.573" Score="5" Body="&lt;p&gt;I think there are a lot of good answers in regards to the curvature of the Earth, but I didn't see anyone addressing the spin of the Earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The atmosphere is naturally dragged along with the surface of the planet. Wind speed is measured relative to a fixed location on the surface. Therefore differences between the movement and the Earth's surface are reflected as wind. Pilots do adjust for the effect of wind on the flight path. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If the pilot is using basic navigation techniques, he would calculate the heading he had to fly with the predicted crosswind to end up at his destination. If there is any crosswind component, the flown heading will be different than the direct heading on the ground or great circle heading. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;With navigation equipment these adjustments can be done in real time. for example if you want to fly a specific GPS heading, but keep drifting to the right you would turn to a more left heading to regain and keep the desired heading. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="43" LastEditDate="2016-05-18T19:39:30.167" LastActivityDate="2016-05-18T19:39:30.167" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27614" PostTypeId="2" ParentId="27607" CreationDate="2016-05-18T15:40:56.887" Score="11" Body="&lt;p&gt;I fly in the UK, and while there is certainly a &quot;standard circuit&quot; (ie pattern) in the syllabus there are many, many fields that have a non-standard circuit for one reason or another. This is often to avoid antagonizing unfriendly neighbors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's also the fact that the NAP is not a rule or regulation, it's more how the airfield management would like you to fly. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I personally don't like the constant aspect climb-out idea at all, it will mean you are paying more attention to aspect than airspeed and looking out for other traffic. It also means that the pattern traffic is not predictable for other visiting your airfield or by others in the pattern. So I would push back on your instructor on this. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for whether you will fail your skills test if you do it would depend on the examiner's view, and what they are looking for. While a constant aspect departure shows skill, I personally would take a dim view of people doing it despite the published departure procedure, even if it is non-binding. I would discuss it with your examiner ahead of time, and practice your circuits how they say they want it, or at least discuss it with them on the day. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastActivityDate="2016-05-18T15:40:56.887" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27615" PostTypeId="1" CreationDate="2016-05-18T16:14:40.850" Score="3" ViewCount="707" Body="&lt;p&gt;I wonder if a jet plane can have helicopter rotor for vertical take off and then, when moving forward just stops that rotor and uses lift from wings like normal plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since rotor blade seems thinner and smaller than wings, I guess when turned off, its drag should be much lower than wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why doesn't that type of hybrid plane exist?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or the drag of the rotor at the jet speed would be so high? If the drag is high, why is it high, since the rotor blade is also airfoil like wing?&lt;/p&gt;&#xA;" OwnerUserId="2516" LastEditorUserId="19" LastEditDate="2016-10-14T14:20:08.733" LastActivityDate="2016-10-14T14:20:08.733" Title="What is the drag of helicopter rotor at jet speed?" Tags="&lt;helicopter&gt;&lt;drag&gt;&lt;fixed-wing&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27616" PostTypeId="1" AcceptedAnswerId="27617" CreationDate="2016-05-18T16:27:51.917" Score="5" ViewCount="2489" Body="&lt;p&gt;Above Victor airway 154 on the IFR enroute low altitude chart, there is a grey zigzag line between &lt;a href=&quot;https://skyvector.com/?ll=32.467442673819086,-82.26361084336237&amp;amp;chart=302&amp;amp;zoom=3&amp;amp;fpl=undefined&quot; rel=&quot;noreferrer&quot;&gt;Dublin VORTAC and LOTTS intersection&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What does the gray zigzag over the segment indicate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7oREv.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7oREv.png&quot; alt=&quot;V154 between DBN and LOTTS&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Credit: &lt;a href=&quot;https://skyvector.com/?ll=32.467442673819086,-82.26361084336237&amp;amp;chart=302&amp;amp;zoom=3&amp;amp;fpl=undefined&quot; rel=&quot;noreferrer&quot;&gt;SkyVector&lt;/a&gt;&lt;/strong&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;" OwnerUserId="2143" LastActivityDate="2016-05-18T18:14:29.603" Title="What is the gray zigzag line over V154 between Dublin VORTAC and LOTTS intersection?" Tags="&lt;instrument-flight-rules&gt;&lt;aeronautical-charts&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27617" PostTypeId="2" ParentId="27616" CreationDate="2016-05-18T16:27:51.917" Score="5" Body="&lt;p&gt;According to the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/#ifr-airspace-information&quot; rel=&quot;nofollow noreferrer&quot;&gt;“Airspace Information” section&lt;/a&gt; of &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA Aeronautical Chart User’s Guide&lt;/a&gt;, it is a low-altitude unusable route. The high-altitude flavor is similar in shape with a smaller amplitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/media/Chart_Users_Guide_12thEd.pdf#page=62&quot; rel=&quot;nofollow noreferrer&quot;&gt;page 62 of the Guide PDF&lt;/a&gt;, if you prefer.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;UNUSABLE ROUTE&lt;/strong&gt; &lt;a href=&quot;https://i.stack.imgur.com/VEonw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VEonw.jpg&quot; alt=&quot;Low- and high-altitude unusable routes&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In this particular case, observe the overprint on 110 in the compass rose surrounding DBN, which indicates abnormal status. The Airport/Facility Directory entry for Dublin VORTAC (as of the 31 MAR 2016 publication) reads, with added emphasis:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;DUBLIN&lt;/strong&gt; N32°33.81′ W82°49.80′ NOTAM FILE MCN.&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;(L) VORTAC&#xA;   113.1   DBN   Chan 78   276º 7.9 NM to W H 'Bud' Barron. 306/5W.&#xA;  HIWAS.&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;VOR portion unusable:&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;215°–285° byd 10 NM blo 3,500’&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&lt;strong&gt;001°–139° byd 33 NM&lt;/strong&gt;&lt;br&gt;&#xA;  &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&lt;strong&gt;001°–139° blo 5,000’&lt;/strong&gt;&lt;br&gt;&#xA;  RCO&#xA;   122.1R 122.6 113.1T (MACON RADIO)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note that the DBN 110 radial falls within the 001-139° unusable range. Beyond LOTTS intersection, V154 is defined with reference to the Savannah VORTAC.&lt;/p&gt;&#xA;" OwnerUserId="2143" LastEditorUserId="2143" LastEditDate="2016-05-18T18:14:29.603" LastActivityDate="2016-05-18T18:14:29.603" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27618" PostTypeId="2" ParentId="27615" CreationDate="2016-05-18T16:36:24.660" Score="3" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;So why doesn't that type of hybrid plane exist?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This type of plane does not exist largely because there is a simpler way to go about this that has already been done with some success. Planes like the Harrier are capable of &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;VTOL&lt;/a&gt; by simply re-directing the exhaust of the jet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r4x7p.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r4x7p.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://en.mercopress.com/data/cache/noticias/34734/0x0/harrier.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In this case you reduce the amount of moving parts by not needing both a regular jet system and a helicopter mechanism (which requires a lot of up keep) instead its simply easier to have a directed nozzle&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6ceBF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6ceBF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/5/5d/Vector-nozzle-sea-harrier-jet-common.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This idea has been carried over into the prop world with &lt;a href=&quot;https://en.wikipedia.org/wiki/Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeings V-22 Osprey&lt;/a&gt; which has tilt control rotors that allow for &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;VTOL&lt;/a&gt; but are also used for forward flight. In this case &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wTi9g.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wTi9g.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://blogs-images.forbes.com/lorenthompson/files/2015/01/Osprey-1940x1165.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To directly answer the drag question, yes the drag would be high (some one else may be able to provide a specific number or the math) but like anything else the design could be built it just would not be very efficient. Since you can generally control the pitch of a helicopter rotor you could potentially (on an even numbered rotor system) orient at least 2 of them to act like small wings and generate very limited lift to assist you even in their static situation. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like most things in aviation planes are built for a given mission profile. &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;VTOL&lt;/a&gt; fits certain cases like anding on an aircraft carrier or in other hard to reach places but things like commercial planes already have a large runway based infrastructure to support them. Any hard to reach place that you need to land at most likely also means your loads are small and a helicopter will suffice, you would need a large hard to reach place that had constantly large loads going in and out to justify a sizable commercial plane that had &lt;a href=&quot;https://en.wikipedia.org/wiki/VTOL&quot; rel=&quot;nofollow noreferrer&quot;&gt;VTOL&lt;/a&gt; capability. While there are some applications for this in the military space (carrier landings come to mind) there are other systems that have been found to be efficient to use. Interestingly enough the directed exhaust from the new F-35's has caused issues on the deck of aircraft carriers.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-18T16:36:24.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27620" PostTypeId="2" ParentId="27615" CreationDate="2016-05-18T17:21:59.160" Score="4" Body="&lt;p&gt;There were actually some experiments with &lt;a href=&quot;https://en.wikipedia.org/wiki/Rotor_wing#Stopped_rotors&quot; rel=&quot;nofollow&quot;&gt;stopped rotor&lt;/a&gt;. Furthest with the actual implementation was probably the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-50_Dragonfly&quot; rel=&quot;nofollow&quot;&gt;Boeing X50 Dragonfly&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/File:Boeing_X-50A.jpg#/media/File:Boeing_X-50A.jpg&quot; rel=&quot;nofollow&quot;&gt;&lt;img src=&quot;https://upload.wikimedia.org/wikipedia/en/8/8d/Boeing_X-50A.jpg&quot; alt=&quot;Boeing X-50A.jpg&quot;&gt;&lt;/a&gt;&lt;br&gt;By Source, Fair use of copyrighted material in the context of &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-50_Dragonfly&quot; rel=&quot;nofollow&quot; title=&quot;Boeing X-50 Dragonfly&quot;&gt;Boeing X-50 Dragonfly&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The main reasons I can think of why nothing like this reached production yet are:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;When the rotor spins, the blade on one side moves aft and needs to have its leading edge face aft, but when the rotor is stopped, both sides need the leading edge facing forward. So either the airfoil must be symmetric, but that has really poor efficiency, or some blades have to turn somehow, which is complicated.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To be light, rotor blades are normally very flexible and rely on the centrifugal force to keep them straight under load. But when they stop, they won't have such force, so they must be much stiffer, which makes them bit too heavy to spin.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Having separate wings and rotor would add a lot of weight, especially since the rotor would still have to be made strong enough to resist the aerodynamic loads when stopped.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-05-18T17:21:59.160" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27621" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T17:26:35.883" Score="5" Body="&lt;p&gt;There have been good answers, but all seem to miss one aspect.&lt;br&gt;&#xA;The aircraft does not maintain a constant distance to the surface of the earth. It simply maintains a level, where the atmospheric pressure is at a set target.&lt;br&gt;&#xA;To clarify:&lt;br&gt;&#xA;Autopilot (or the pilot) wants to maintain a contstant reading on the altimeter. This reading is merely a calibrated difference to a reference level, which normally is set to 1013,25hPa (or 29,92inHg) on cruise flight. This means that maintaining an altitude of about 30000ft, you want to maintain a pressure level of 300hPa. I say about 30000ft, because the true altitude of this level varies greatly, affected by airmass temperature and air pressure.&lt;br&gt;&#xA;Jan Hudec was close to this on his answer, though I'd like to make a few corrections. First of all, the levels aren't isobars. Isobars is by definition &lt;em&gt;&quot;an imaginary line or a line on a map or chart connecting or marking places of equal barometric pressure&quot;&lt;/em&gt; &lt;a href=&quot;http://www.merriam-webster.com/dictionary/isobar&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;. Second of all, there's no need to over-complicate things: the (auto)pilot monitors the altimeter, and does the necessary corrections. It would do so if the aircraft was out of trim also.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-05-18T17:26:35.883" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27622" PostTypeId="2" ParentId="27615" CreationDate="2016-05-18T18:03:02.410" Score="2" Body="&lt;p&gt;Anything that uses a rotor to take-off vertically is &lt;a href=&quot;https://i.stack.imgur.com/8WOOs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;most inefficent when lifting, hovering or moving slowly&lt;/a&gt;.  This is most obvious when a helicopter is at max weight or in &quot;hot and heavy&quot; conditions when it &lt;a href=&quot;https://aviation.stackexchange.com/questions/22492/should-helicopters-fly-when-they-the-lack-power-for-vertical-climb-out-of-ground&quot;&gt;might not be possible to take-off vertically&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to lift vertically, thrust must be greater than weight.  This is not true for a &quot;conventional&quot; aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use a rotor only for lifting off, then that rotor becomes nothing but extra weight (and complexity) that you don't need.  Maybe you could use the stopped rotor to generate some lift in a similar fashion to a conventional wing but as others have pointed out, to make a rotor blade which is rigid enough to act as a static wing and can still handle the forces generated when rotating is a serious engineering challenge that will add more weight and complexity (because the rotor hub must have hinges that can absorb the forces when rotating but keep the blade rigid when stationary).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You also need some complex, and therefore heavy, mechanism for tranisitioning the thrust from the rotor whilst lifting to whatever propulsion you use for forward flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More weight, more complexity, more maintenance, more cost, more to go wrong.  What's not to like? ;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other answers also point out better solutions such as vectored thrust and using the same rotors to lift and to provide thrust in forward flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Add this all together and you have a solution for a problem which doesn't exist.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-05-18T18:27:01.427" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27623" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T18:50:35.450" Score="11" Body="&lt;p&gt;The posted answers are good.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A tangent (pun intended) answer: if &lt;em&gt;adjusting for curvature of earth&lt;/em&gt; was required, it infers that you could accidentally fly into space.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you could accidentally fixed-wing fly into space, we wouldn't need sophisticated and powerful rockets.&lt;/p&gt;&#xA;" OwnerUserId="14549" LastEditorUserId="14549" LastEditDate="2016-05-18T20:34:35.740" LastActivityDate="2016-05-18T20:34:35.740" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27624" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T19:25:12.737" Score="9" Body="&lt;p&gt;It's no different than driving.  If you drive absolutely straight you'll eventually leave the road.  The road lines are meant to be followed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what is equivalent to the road lines in flight?  Air pressure.  The air pressure reduces the further you are from the surface.  Pilots and autopilots follow the air pressure gradient, trying to keep the plane at a set air pressure.  This pressure is used rather than GPS or &quot;straight flight&quot; because it's one of the many factors that affects flight efficiency - speed vs air resistance vs load bearing capacity of the aircraft.  They are flying, or attempting to fly, in a pressure range that is going to cost the least to accomplish the various goals of the airline.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The air pressure varies according to many factors, but the main factor is height from sea level, and so by flying inside a specific range of pressures, they maintain a reasonably constant height from sea level.  Since &quot;sea level&quot; pressure is curved along with the earth, then what you find is that they automatically follow the curvature of the earth.  In other words, the planes are flying slightly down all the time.&lt;/p&gt;&#xA;" OwnerUserId="1073" LastActivityDate="2016-05-18T19:25:12.737" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27626" PostTypeId="2" ParentId="27603" CreationDate="2016-05-18T19:57:20.417" Score="5" Body="&lt;p&gt;Planes don't stay perfectly level!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That's the long and short of it. As these 600 mph machines go that 1 mile forward, both gravity and air pressure force the plane down those 8 inches. More, actually; these massive metal monstrosities have to put up a fight to be able stay up in the air! That's what the elevators, rudders, engines, airfoils, etc. are all there for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if it were going sufficiently fast (at least &lt;strong&gt;25,020 mph&lt;/strong&gt;), it would overpower gravity, leave the atmosphere, and enter orbit. I hope it has engines that don't rely on air, and a body made of &lt;a href=&quot;https://en.wikipedia.org/wiki/Reinforced_carbon%E2%80%93carbon&quot; rel=&quot;nofollow&quot;&gt;reinforced carbon-carbon&lt;/a&gt;!&lt;/p&gt;&#xA;" OwnerUserId="3140" LastEditorUserId="3140" LastEditDate="2016-05-20T15:35:39.110" LastActivityDate="2016-05-20T15:35:39.110" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27628" PostTypeId="1" AcceptedAnswerId="27629" CreationDate="2016-05-18T20:39:44.103" Score="4" ViewCount="3498" Body="&lt;p&gt;According to the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow&quot;&gt;Chart Supplement&lt;/a&gt;, Orlando International airport (&lt;a href=&quot;http://airnav.com/airport/KMCO&quot; rel=&quot;nofollow&quot;&gt;KMCO&lt;/a&gt;) is an LRA (landing rights airport). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What permission is needed to fly an aircraft to an airport classified as LRA? Can I just file a VFR flight plan, take off under VFR from somewhere in Florida, enter the class B with a clearance, and land there?&lt;/p&gt;&#xA;" OwnerUserId="6831" LastEditorUserId="62" LastEditDate="2016-05-19T15:05:16.540" LastActivityDate="2016-05-19T15:05:16.540" Title="Do I need special permission to land at a Landing Rights Airport?" Tags="&lt;faa-regulations&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27629" PostTypeId="2" ParentId="27628" CreationDate="2016-05-18T20:54:58.520" Score="5" Body="&lt;p&gt;According to the &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/19/122.14&quot; rel=&quot;noreferrer&quot;&gt;FAR's&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(2) Private aircraft. The pilots of private aircraft are required to&#xA;  secure permission to land from CBP following transmission of the&#xA;  advance notice of arrival via an electronic data interchange system&#xA;  approved by CBP, pursuant to § 122.22. Prior to departure as defined&#xA;  in § 122.22(a), from a foreign port or place, the pilot of a private&#xA;  aircraft must receive a message from CBP that landing rights have been&#xA;  granted for that aircraft at a particular airport.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This only matters if you are inbound from an out of country origin. An LRA airport is &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Landing rights airport. A landing rights airport is any airport, other than an international airport or user fee airport, at which flights from a foreign area are given permission by Customs to land.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-18T20:54:58.520" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27630" PostTypeId="2" ParentId="27569" CreationDate="2016-05-18T21:16:01.133" Score="10" Body="&lt;p&gt;Boeing called the aircraft CX-HLS( Cargo Experimental - Heavy Logistics System). It never entered production though. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The below image is of a scaled down model of the CX-HLS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CAxrz.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CAxrz.jpg&quot; alt=&quot;Boeing CX-HLS Model at Boeing Corporate Archives - 1963/64&quot;&gt;&lt;/a&gt;&#xA;&lt;strong&gt;&lt;em&gt;Source&lt;/em&gt;&lt;/strong&gt;: &lt;em&gt;Boeing Archives - Bellevue, Washington USA&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Details about the CX-HLS can be found &lt;a href=&quot;http://airwaysnews.com/html/museums/boeing-archives-bellevue-washington-usa/boeing-cx-hls-model-196364/19149&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="3010" LastEditorUserId="3010" LastEditDate="2016-05-19T20:16:14.637" LastActivityDate="2016-05-19T20:16:14.637" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27631" PostTypeId="2" ParentId="27590" CreationDate="2016-05-19T00:07:34.497" Score="1" Body="&lt;p&gt;Usually no, although in some cases you may be able to dump fuel by exploiting features of the fuel system. Why not on smaller planes? Fuel jettisoning systems were only ever &lt;em&gt;required&lt;/em&gt; for transport-category aircraft.  There is some reasoning behind this link, since many transport category aircraft perform comparatively poorly at MTOW and would take a long time to burn off the difference between maximum take-off and maximum landing weights.  Many GA aircraft can even land at their maximum take-off weights and so don't list a separate landing weight. (See, for example, the &lt;a href=&quot;http://www.skywarriorinc.com/downloads/POH%20BOOKS/172N%20POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;C172 POH&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason for this discrepancy between small and large aircraft, like many differences between transport category and GA aircraft, is in part due to practicality and in part due simply to regulation.   Fuel jettisoning is required on many transport aircraft but is not required on GA aircraft. The FAA had &lt;a href=&quot;https://books.google.com/books?id=l105AAAAIAAJ&amp;amp;pg=PA206#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;a regulation&lt;/a&gt; that stated (though &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/25.1001&quot; rel=&quot;nofollow noreferrer&quot;&gt;it's since changed&lt;/a&gt; to be performance, not weight-based):&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Sec. 25.1001 Fuel jettisoning system.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) If the maximum takeoff weight is more than 105 percent of the&#xA;  maximum landing weight, there must be a fuel jettisoning system able&#xA;  to jettison enough fuel to bring the takeoff weight down to the&#xA;  maximum landing weight...&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;version of 25.1001 effective on 02/01/1965.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is good reason for the distinction between small GA aircraft and large transport aircraft in certification requirements.  First, many GA aircraft are designed to be able to land and take-off at the same weight.  Other reasons include performance consideration and that fuel flow is not proportional to max fuel, in part because larger aircraft usually have longer ranges. Longer range means more distance to burn off all the fuel, which usually makes it harder to burn off any unwanted fuel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to be technical, the driving factors here are the performance at MTOW and the practicality of burning off the difference in MTOW (max takeoff weight) and max landing weight, not fuel fraction (fuel available/empty weight) and not necessarily the ratio of MTOW to max landing weight. As counterexamples to the notion that fuel fraction or MTOW/MLW are important, the F7x can hold almost 90% of its empty weight in fuel but can also land at almost 90% of its take-off weight and so has no fuel dumping.  Even a Learjet 60XR, with a MTOW to MLW ratio worse than an A320, can burn off the difference in fuel during a little more than a 300 nm trip. By comparison, by my calculations a 757-200 could make a 2,000 nm trip without burning off the difference between maximum take-off and maximum landing weights, and &lt;a href=&quot;http://www.dailymail.co.uk/travel/article-3519817/Ryanair-flight-returns-Manchester-following-bird-strike.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;circling for hours burning off fuel like that tends to horrify passengers&lt;/a&gt;. (Source: Plane Purchasing Handbook 2012 and &lt;a href=&quot;http://www.boeing.com/resources/boeingdotcom/company/about_bca/startup/pdf/historical/757_passenger.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this 757 presentation&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You may also want to read: &lt;a href=&quot;https://aviation.stackexchange.com/questions/9393/why-doesnt-the-737-have-a-fuel-dump-nozzle&quot;&gt;Why doesn&amp;#39;t the 737 have a fuel dump nozzle?&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/2854/when-are-aircraft-required-to-dump-fuel-for-emergency-landings?lq=1&quot;&gt;When are aircraft required to dump fuel for emergency landings?&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-05-19T16:38:56.073" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27632" PostTypeId="2" ParentId="11326" CreationDate="2016-05-19T00:46:59.693" Score="4" Body="&lt;p&gt;After searching for morphing I stumbled on to this question and just wanted to add a few things to what was already said since the question is a bit old, in case anyone like myself happens across it during a search...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question: What is the perceived advantage of this new generation of wing warping technology, what are barriers to its adoption, and how practicable is it for it to trickle down to general aviation? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Answer: A warped wing or a morphing airfoil, shows significant improvement in lift to drag ratio and in decreasing the overall drag of the vehicle.  Depending on the specific technology many of the components are internal which has several benefits (decreased drag, increased life span) and with advancing technology and research the power consumption and additional weight of these components has been significantly reduced.  In the world of UAS's morphing wings have been show in some cases to increase stall AoA by 8 degrees or more (see &lt;a href=&quot;https://www.google.com/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=1&amp;amp;ved=0ahUKEwiU_Mnr8eTMAhXB0RoKHTskB9sQFggfMAA&amp;amp;url=http%3A%2F%2Fwww.ewp.rpi.edu%2Fhartford%2F~ernesto%2FF2011%2FEP%2FMaterialsforStudents%2FFerrari%2FShyy2005.pdf&amp;amp;usg=AFQjCNEmDbkJp3tgjJqZqRAnu3M2lNMX_g&amp;amp;sig2=3J5NxIXr7bQ3-jmWY0LERA&quot; rel=&quot;nofollow&quot;&gt;Membrane Wing-Based Micro Air Vehicles&lt;/a&gt;) The complexity of analyzing morphing wings and airfoils however can present a challenge, as now there is significantly more fluid structure interaction, requiring solvers with more capabilities, or an increase in experimental data.  Large scale implementation is currently underway (see &lt;a href=&quot;http://www.nasa.gov/press-release/nasa-successfully-tests-shape-changing-wing-for-next-generation-aviation&quot; rel=&quot;nofollow&quot;&gt;NASA Successfully Tests Shape-Changing Wing for Next Generation Aviation&lt;/a&gt; or &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/2015/may/04/morphing-wing-passes-test&quot; rel=&quot;nofollow&quot;&gt;Morphing Wing Passes Test, Business Jet Flew Concept Years in Making&lt;/a&gt;) and in a aerospace world that is concerned about improvements to &lt;a href=&quot;http://aero.larc.nasa.gov/&quot; rel=&quot;nofollow&quot;&gt;develop faster and more efficient vehicles&lt;/a&gt; this technology holds some appeal.&lt;/p&gt;&#xA;" OwnerUserId="781" LastActivityDate="2016-05-19T00:46:59.693" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27633" PostTypeId="1" CreationDate="2016-05-19T00:49:37.540" Score="10" ViewCount="2971" Body="&lt;p&gt;I've been trying to find the history of flares (as countermeasures to heat-seeking missiles), but have not had much luck. Closest thing has been &lt;a href=&quot;https://en.wikipedia.org/wiki/Infrared_countermeasure&quot;&gt;this wiki article&lt;/a&gt; which has but a single sentence in its history section saying &quot;First deployed during the Vietnam War&quot;, with an explicit &quot;citation needed&quot; tag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flare_(countermeasure)&quot;&gt;Another article&lt;/a&gt; is also surprisingly void of history details, and doesn't even have a history section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Who first conceived of flares as IR countermeasures? When and where were they first used on a large scale?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only hint I have is that the AIM-4 Falcon was the first IR-seeking AA missile to enter service, doing so in 1956. So presumably flares would not have shown up until that year or later.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2017-07-05T00:56:43.600" Title="When were flares first used as IR countermeasures, and by whom?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;missiles&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27635" PostTypeId="2" ParentId="27590" CreationDate="2016-05-19T05:01:26.287" Score="0" Body="&lt;p&gt;The answer is simple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an aircraft's maximum takeoff weight is significantly greater than its maximum landing weight it needs to be able to dump fuel so that it can land quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Small planes, such as C-172, can usually land at maximum takeoff weight. Thus they have no need for fuel dumping capability.There simply is no need for dumping fuel in a C-172 so the aircraft does not have that capability.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-05-19T05:01:26.287" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27636" PostTypeId="1" CreationDate="2016-05-19T06:26:00.240" Score="14" ViewCount="3166" Body="&lt;p&gt;With today's technology in memory storage, where simple voice recorders can record virtually endless durations, why are CVRs limited to only 2 hours. Is it the eternal &quot;cost vs benefit&quot; reason?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wouldn't more recording provide greater insight to investigators in case of any disaster?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastActivityDate="2016-10-03T02:44:12.263" Title="Why are cockpit voice recorders limited to 2 hours recording?" Tags="&lt;cockpit-voice-recorder&gt;" AnswerCount="2" CommentCount="22" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27638" PostTypeId="2" ParentId="27603" CreationDate="2016-05-19T08:50:13.243" Score="2" Body="&lt;p&gt;Your question is basically &quot;What makes the flight change its direction continuously?&quot; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's consider the case of a plane flying overhead right now. If we are told that the plane is in level flight, the vertical, downward pull of gravity is equal to the vertical, upward lift. Further both forces are perpendicular to the fuselage and cancel out.&lt;br&gt;&#xA;Imagine what happens a very very short time later when the plane has moved a very small distance ahead &lt;strong&gt;in a straight line&lt;/strong&gt;. Since the plane has moved in a straight line, the lift is still pointing upwards and perpendicular to the the fuselage, but gravity is pointing towards the center of the Earth. So now only a part of the lift is countering the gravity, and there is a resultant gravitational force that will pull the aircraft down towards the center of the Earth.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is very similar to how you can tie a stone to a rope and whirl it. The stone will go around in circles. The force of the string (tension) keeps the direction of the stone changing continuously without affecting the speed.&lt;/p&gt;&#xA;" OwnerUserId="14983" LastEditorUserId="19381" LastEditDate="2017-10-18T13:09:07.353" LastActivityDate="2017-10-18T13:09:07.353" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27641" PostTypeId="1" AcceptedAnswerId="27643" CreationDate="2016-05-19T10:45:22.887" Score="5" ViewCount="210" Body="&lt;p&gt;I was watching a &lt;a href=&quot;https://www.youtube.com/watch?v=9tzga6qAaBA&quot; rel=&quot;noreferrer&quot;&gt;youtube video&lt;/a&gt; about high voltage cable inspections performed with helicopters. It can be seen how the helicopter has to reach the same electric potential as the wire, something that normally does not occur to other crafts.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was wondering, is there any kind of special instrumentation/equipment that must be installed on the helicopters to perform such operations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are the pilots aided in any special way to maintain a stable hover or it boils down to skill and training?&lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-05-19T11:10:50.853" Title="Is special equipment required to perform high-voltage line inspections?" Tags="&lt;helicopter&gt;&lt;equipment&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27642" PostTypeId="1" CreationDate="2016-05-19T11:00:54.717" Score="2" ViewCount="4501" Body="&lt;p&gt;Why, on a Cessna 172S, there is a positive voltage reading on the Main bus when only the standby battery switch is on? In the checklist it says &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;verify M BUS Volts are 1.5volts or less.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I thought that the standby battery was supposed to power only the essential bus.&lt;/p&gt;&#xA;" OwnerUserId="14987" LastEditorUserId="19" LastEditDate="2016-06-21T15:52:37.097" LastActivityDate="2016-06-21T15:52:37.097" Title="How is the Cessna 172S G1000 Electrical System powered?" Tags="&lt;cessna-172&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27643" PostTypeId="2" ParentId="27641" CreationDate="2016-05-19T11:10:50.853" Score="5" Body="&lt;p&gt;I work in this area and, to my knowledge, I never heard about any special aid to help the pilot. They know precisely which are the wind speed limitations to do the work safely, the rest is basically skill.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What they do install in helicopters, is the so called Wire Strike Protection System (WSPS), which should cut the cable if the helicopter strikes it, avoiding damages on the main rotor (see the picture &lt;a href=&quot;https://upload.wikimedia.org/wikipedia/commons/b/bf/Ntsp-oh58-N170FR-070205-01cr.jpg&quot; rel=&quot;noreferrer&quot;&gt;https://upload.wikimedia.org/wikipedia/commons/b/bf/Ntsp-oh58-N170FR-070205-01cr.jpg&lt;/a&gt; that Bell has two WSPS, one over the cabin another underneath the avionics bay). But this is more important on power line inspection, which is made at around 60-80 km/h with cameras and LiDARs. When the helicopter is hovering by the cables this doesn't bring much aid.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But this is a risky job anyway and if you search, you will find plenty of accidents which happened with helicopters and power lines.&lt;/p&gt;&#xA;" OwnerUserId="11121" LastActivityDate="2016-05-19T11:10:50.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27644" PostTypeId="2" ParentId="27603" CreationDate="2016-05-19T12:26:29.427" Score="2" Body="&lt;p&gt;I am not really qualified to answer, but did so on account of the many answers implying that some form of pilot control is necessary to keep an airplane following the curvature of the earth. Input from a real aerodynamicist would be appreciated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Several answers state that when an airplane is flown to a constant altitude, it implicitly follows that curve. True enough, but the question asks whether pilot control is necessary. Are there physical constraints relevant to the question?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airplane were to follow a tangent, rather than the curvature of the earth, it would experience at least two effects: the direction of the earth's gravitational field would change, causing its weight vector to rotate rearwards, and the local air density would decrease as the aircraft's distance to the earth increases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the weight vector rotates  backwards, it increasingly retards the airplane, and if it is longitudinally stable, it will, as a result, tend to pitch downwards. The effect of decreasing density seems more complicated, on account of its effects on power as well as aerodynamic forces, but there seems to be a general tendency for a trimmed, longitudinally stable airplane to be stable in density altitude - see &lt;a href=&quot;https://aviation.stackexchange.com/a/12511/1981&quot;&gt;What does it mean for a plane to be aerodynamically stable?&lt;/a&gt;. It is certainly true that every airplane has a maximum achievable altitude, determined by physics. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Both of these effects (longitudinal stability with respect to the local gravity field, and stability in density altitude) will tend to guide the airplane to follow the curvature of the Earth without pilot input.&lt;/p&gt;&#xA;" OwnerUserId="1981" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-22T13:48:26.117" CommentCount="0" CommunityOwnedDate="2016-05-19T21:26:10.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="27645" PostTypeId="1" CreationDate="2016-05-19T13:06:08.467" Score="7" ViewCount="763" Body="&lt;p&gt;Why are cannular type burners used in aircraft engines if annular type have more advantages over it?&lt;/p&gt;&#xA;" OwnerUserId="14618" LastEditorUserId="1696" LastEditDate="2016-05-19T16:53:05.723" LastActivityDate="2017-12-09T06:13:52.953" Title="Why would a jet engine use cannular combustors if the annular design is superior?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;&lt;turbine&gt;&lt;turbofan&gt;&lt;combustion&gt;" AnswerCount="3" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27646" PostTypeId="1" AcceptedAnswerId="27650" CreationDate="2016-05-19T14:39:50.147" Score="6" ViewCount="624" Body="&lt;p&gt;First, I'm not looking for speculation on an accident, I just want to know if pilots are trained to make certain maneuvers in response to an emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In reading about the jet that just went down in Egypt, &lt;a href=&quot;http://www.cnn.com/2016/05/18/middleeast/egyptair-flight-disappears/index.html&quot;&gt;the story&lt;/a&gt; stated&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;It turned 90 degrees left and then a 360 degree turn toward the right, dropping from 38,000 to 15,000 feet and then it was lost at about 10,000 feet,&quot; Kammenos added.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Assuming the report is accurate, are those maneuvers a standard procedure of some kind? Are pilots trained to maneuver like that in an emergency? If so, in what type of emergency would those maneuvers be useful?&lt;/p&gt;&#xA;" OwnerUserId="14994" LastEditorUserId="62" LastEditDate="2016-05-19T15:10:44.900" LastActivityDate="2016-05-20T19:19:02.827" Title="Are sudden turns and descents a standard emergency procedure?" Tags="&lt;emergency&gt;&lt;maneuver&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27648" PostTypeId="2" ParentId="27636" CreationDate="2016-05-19T16:00:02.863" Score="7" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;With today's technology in memory storage, where simple voice&#xA;  recorders can record virtually endless durations, why are CVRs limited&#xA;  to only 2 hours. Is it the eternal &quot;cost vs benefit&quot; reason?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is at least partially the result of the fact that CVR's (and FDR's alike) do not necessarily include the latest and greatest tech out there. &lt;a href=&quot;https://aviation.stackexchange.com/questions/27636/why-are-cockpit-voice-recorders-limited-to-2-hours-recording#comment68365_27636&quot;&gt;As mentioned in the comments&lt;/a&gt;, while they are flying today they were not designed today, last week or even last year. The FAA has some very strict regulations on CVR/FDR from a storage stand point (&lt;a href=&quot;https://aviation.stackexchange.com/questions/26360/what-data-file-format-is-used-by-fdrs&quot;&gt;you can check out this related question for more info&lt;/a&gt;). It's hard enough to get things approved for use as is, there may be current efforts out there to integrate better storage (and we have seen it slowly) but chances are you will see today's tech in airplanes in 5-10 years, not next week. Of course historically this may have been a data medium limitation and over the years the 2 hours has been found to be sufficient and has become a standard. &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Wouldn't more recording provide greater insight to investigators in&#xA;  case of any disaster?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, no. While there are of course cases that can refute this, the overwhelming amount of aviation accidents happen in a relatively short period of time. If we look back at the history of aviation accidents (for which there is a great deal of data) the chain of events generally occurs over minutes not hours thus recording 2 hours of data prior to an impact is more than enough. If you watch any analysis of an investigation (there are a variety of shows out there on it these days) you will see that more often than not they are analyzing the last minutes of flight data and possibly the conversation that lead up to and occurred during that time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have seen a great deal of tech progression in CVR/FDR's over the years. The earliest ones were tape and some even had a primitive system that physically punched data onto a metallic strip. This slowly moved to magnetic tape and now some digital tech has been integrated. It's not that it won't happen it just won't happen overnight.      &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-10-03T02:44:12.263" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27649" PostTypeId="2" ParentId="27645" CreationDate="2016-05-19T16:29:19.537" Score="6" Body="&lt;p&gt;Modern jet engines do not use can or cannular combustors. GE made the switch to annular combustors by at least the J85, which had a first engine to test in the 1950s. The TF39 (1964) engine formed the basis of the CF6, which also uses an annular combustor. I don't know of any GE engine since the TF39 that did not use some form of annular combustors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Modern Pratt and Rolls engines also use some form of annular combustors, but I am not sure when they made the switch.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2017-12-08T21:15:26.933" LastActivityDate="2017-12-08T21:15:26.933" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27650" PostTypeId="2" ParentId="27646" CreationDate="2016-05-19T16:59:24.657" Score="10" Body="&lt;p&gt;There are no emergency procedures I'm aware of that requires a pilot to turn left 90 degrees and then turn right 360 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is a procedure for situations requiring rapid descent for things like medical emergencies and fires.  They consist of a 45 degree banked, full-flap, power-idle descent flown at maximum flap extension speed.  So it is a spiraling-turn descent.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, the Cessna 172N checklist instructs the pilot to slip in the opposite direction from a wing fire to keep the flames blown in an outboard direction.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="3386" LastEditDate="2016-05-20T16:43:57.593" LastActivityDate="2016-05-20T16:43:57.593" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27651" PostTypeId="2" ParentId="27633" CreationDate="2016-05-19T16:59:59.937" Score="6" Body="&lt;p&gt;The document &lt;a href=&quot;http://www.dtic.mil/get-tr-doc/pdf?AD=ADA495417&quot; rel=&quot;noreferrer&quot;&gt;Genesis of Infrared Decoy Flares- The early years from 1950 into the 1970s&lt;/a&gt; by Naval Surface Warfare Center has a lot of details about the work done on decoy flares in the initial stages, at least in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to the report, the first use of IR flares was not as a decoy, but as a tracking device for drones. The T-131 flare was used in this capacity. From the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;NOTS, China Lake was involved with infrared target augmentation since 1954. ... The T-131 tracking flare developed at NOTS was the first infrared source for drone use. Six to sixteen of these are needed on the F6F-5K drone to provide a suitable signature.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The first IR flare developed as a countermeasure is the NOTS Model 704, which was developed around 1959. However, the studies on decoys for IR started in the mid fifties, though the concept of using flares came later (the initial concepts were towed decoys). From the report:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Hayes Corporation, Birmingham, Alabama initiated infrared countermeasures and radiation suppression studies in 1955. ... There was a need about 1957 to create a decoy device that would simulate the signature of a turbojet engine. Instead of the pyrotechnic decoy flare approach,&#xA;  ... proposed an inflatable envelope that absorbs the energy from a self-contained pyrotechnic and re-radiates this energy at a lower temperature approximating that of the heated surfaces of the turbojet engine.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Initial flares (RR-77, probably) were fitted in the B-47 and B-52 bombers, which were deployed through the AN/ALE-14 dispenser around 1960. Though the report has indications that the flares were used in the Vietnam war, there is no data on the exact time and location of the use of flares in combat. However, we can be sure that the IR flares were used in combat in Vietnam. The report says,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In 1967, Dr. Edwards of Air Development Test Center at Eglin Air Force Base, requested Picatinny Arsenal to improve the ALA-17 flare. The Air Force wanted a quick fix to the poor rise time of the ALA-17 flare. They also required that a single ALA-17 flare would have decoy capability to protect B-52 bombers in Southeast Asia against seekers operating in the 2μm to 3μm and 3μm to 5μm bandpass.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;indicating feedback from combat operations. Though I'm sure that the Soviets too were developing IR flares at the same time, not much detail is available about their effort.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="3386" LastEditDate="2016-05-19T19:05:19.957" LastActivityDate="2016-05-19T19:05:19.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27652" PostTypeId="2" ParentId="27645" CreationDate="2016-05-19T17:12:47.023" Score="11" Body="&lt;p&gt;Single combustor cans are simpler to develop. To get the ignition and combustion process right in an annular combustor is quite a challenge. When the first jet engines were developed, &lt;a href=&quot;https://en.wikipedia.org/wiki/Junkers_Jumo_004&quot; rel=&quot;noreferrer&quot;&gt;Junkers&lt;/a&gt; decided for separate cans while &lt;a href=&quot;https://en.wikipedia.org/wiki/BMW_003&quot; rel=&quot;noreferrer&quot;&gt;BMW&lt;/a&gt; wanted to design a theoretically superior annular combustor. In the end, the troubles with the combustor meant that Junkers got their engine fielded much earlier, even though BMW had started their jet engine development before Junkers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With today's CFD tools the annular design is not quite such a challenge any more.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-21T05:48:21.150" LastActivityDate="2016-05-21T05:48:21.150" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27653" PostTypeId="2" ParentId="27636" CreationDate="2016-05-19T17:47:15.747" Score="12" Body="&lt;p&gt;Aviation manufacturers generally design the equipment to comply with legal requirements. Under FAA two hours is what is required by law.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;14 CFR  121.359–Operating Requirements:  Domestic,  Flag,  and Supplemental  Operations–Cockpit  Voice  Recorders&lt;/p&gt;&#xA;&lt;p&gt;(i)  By  April  7,  2012, all  turbine  engine-powered  airplanes  subject to  this  section  that are manufactured  before  April  7, 2010, must  have  a  cockpit  voice  recorder  installed that  also—&lt;/p&gt;&#xA;&lt;p&gt;(1)  Meets  the  requirements  of  §23.1457(d)(6)  or  §25.1457(d)(6)  of  this  chapter, as  applicable;&lt;/p&gt;&#xA;&lt;p&gt;(2)  &lt;strong&gt;Retains  at  least  the  last  2 hours  of  recorded  information using  a  recorder  that  meets  the standards  of  TSO-C123a,  or  later  revision&lt;/strong&gt;;  and&lt;/p&gt;&#xA;&lt;p&gt;(3)  Is  operated  continuously  from  the  use  of  the  checklist  before  the  flight  to completion of  the final checklist at the  end  of  the  flight.&lt;/p&gt;&#xA;&lt;p&gt;(4)  If  transport  category,  meets  the  requirements  in §25.1457(a)(3),  (a)(4),  and  (a)(5) of this chapter.&lt;/p&gt;&#xA;&lt;p&gt;[&lt;em&gt;The following section has the same requirements for aircraft manufactured after April 7, 2010.&lt;/em&gt;]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The flight data recorder is required to retain 15 hours worth of data.&lt;/p&gt;&#xA;&lt;p&gt;FAA allows pilots to erase anything on the CVR recorded 30 min (in some cases 15 min) prior. This is probably something that was negotiated between the NTSB and the pilots union to protect the pilots' privacy.  Since it's written into the statute that way I assume modern digital CVR'S must have a function to erase everything but the last 30 min. (@OSUZorba &lt;em&gt;there's that word again&lt;/em&gt;)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;14 CFR  121.359 (f)  In  complying  with this  section, an approved  cockpit  voice  recorder  having  an  erasure feature  may  be  used, so that  at  any  time  during  the  operation of  the  recorder, information recorded more than  30  minutes  earlier  may  be erased  or  otherwise obliterated.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;This was most likely in response to the 1979 incident that occurred on &lt;a href=&quot;https://en.wikipedia.org/wiki/TWA_Flight_841_%281979%29?wprov=sfla1&quot; rel=&quot;noreferrer&quot;&gt;TWA flight 841&lt;/a&gt; where the pilot was accused of improperly extending flaps during cruise but had erased the CVR when they landed,  so they had no proof. At the time CVR's were still fairly new and pilots balked at having their conversations recorded for privacy reasons, so it was common practice to erase it after each flight. There is still some concern over privacy issues since in some situations the recording can open the pilot up to legal liability.&lt;/p&gt;&#xA;&lt;p&gt;There are really only a handful of cases where a longer recording would have been useful, most of which involved pilot incapacitation. In 2014 EASA proposed extending the requirement. The European Cockpit Association, which represents pilots released a position paper &lt;a href=&quot;http://www.google.com/url?q=https://www.eurocockpit.be/sites/default/files/eca_position_easa_opinion_01_2014_on_cvr_uld_14_0626_f.pdf&amp;amp;sa=U&amp;amp;ved=0ahUKEwjmy9nb2ObMAhVG5yYKHfYCB-g4ChAWCBgwBQ&amp;amp;sig2=pwzgOC_dzBPS1KSxmGOhCQ&amp;amp;usg=AFQjCNGz3Hwm_w1VoqcsQHEarZJpcmm6Sg&quot; rel=&quot;noreferrer&quot;&gt;.pdf&lt;/a&gt; stating that they would only support the extension if there were also systems in place to ensure that only the pertinent portions could be used and any other conversation could not be leaked to the public or used in jurisdictions where there are no legal requirements to maintain pilots' privacy.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;ECA  stresses  the  following:&lt;/p&gt;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;&lt;p&gt;Pilots  submit  to such  recording  under  the  strict  condition  that  the  CVR  data is  to be  used exclusively by  accident  investigation authorities in  the  context  of  their  safety  investigations.  Pilots  are  one of  the few  professions  that  agree  to  being  recorded  at  their  workplace  and  the  consequent  infringement  of their  privacy&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;National  and  European  legislators  recognise  the  need  to  protect  CVR  recordings  (Reg.  996/2010). However,  despite  various  legal  provisions  at  EU  and  national  level,  as  well  as  best  practices  in many  airlines,  CVR  data  or  their  transcripts  have  too  often  leaked  to  the  public  and  media , exposing  data  with  private  and  personal  content  –  sometimes  the  last  minutes  of  the  crews’  lives  – to  a  wide  audience,  generating  speculation,  interpretations  and  apportioning  blame  –  in  a  way  that may  be  far  removed  from  what  actually  happened,  what  contributed  to  the accident  and why.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;This  inappropriate  use  and  distribution  of  sensitive  CVR  data  beyond  accident  investigation agencies  negatively  affects  Just  Culture  and  the  safety  improvement  efforts  in  Europe.  Extending CVR duration would increase the  quantity  of  data  available for  misuse  significantly.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Leaking  of  CVR  data  results  in speculation that  increases  the  pressure on  accident  investigators,  on the  judiciary  to  act  quickly  to  hold  accountable those  ‘responsible’,  and  on  other  authorities  or  public figures  to  come  up  with  quick  answers,  rather  than  waiting  for  the  Final  Report  to  be  published  and generating  mature  safety  improvements.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Increasing  CVR  duration  would  also  increase  the  data  that  is  potentially  available  to  the  airline management.  While   many  companies  in  Europe  have  internal  procedures  –  and  sometimes agreements  with  the  pilot  representatives  –  in  place  to  ensure  sensitive  data  is  not  misused,  this  is not  the  case  for  all  companies.  Hence,  an  increased  recording  time  –  combined  with  very  powerful digital  storing  facilities  and  the  possibility  to  cross-check  CVR  and  FDM  data  –  would  also  increase the  scope  for  (un)intentional  (ab)use  of  such  data  by  company  management  for  other  than  safety purposes  (e.g.  any  form  of  disciplinary  measures).  Although  this  would  not  be  in  line  with  EU legislation,  not  all  airlines  are  as exemplary  as  some,  and not  all  legislation is adequately  enforced.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Increasing  CVR  duration  on  European aircraft  also increases  the  risk  of  CVR  data being  used  –  and potentially  made  public  –  by  non-European  authorities,  which  are  not  bound  by  EU  legislation  and the  protections  contained  therein.  This  is  the  case  especially  for  long-haul  operations  (at  which  an increase  of  the  recording  time  is  actually  aimed)  where  the  majority  of  the  flight  is  outside  Europe.  If an  accident  happens  outside  Europe,  the  national  safety  and  judicial  authorities  will  be  entitled  to seize  the  CVR  and  will  be  bound  by  their  own  local  laws,  by  local  political  considerations,  and general  public  pressure.  –  This  would be  an  unintended  –  but  very  real  –  consequence  that  must  be taken  into  account.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-19T18:07:19.867" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27654" PostTypeId="2" ParentId="27590" CreationDate="2016-05-19T19:07:31.557" Score="0" Body="&lt;p&gt;the Mooney M20M has a gross take-off weight of 3368, and a gross landing weight of 3200#. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although not designed for fuel dumping, it has a operable valve on the floor of the right seat that is used for draining the lowest part of the fuel system, and this valve &lt;em&gt;could&lt;/em&gt; be used to dump 168# or 28 gallons of fuel, although it would take a fairly long time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The better technique is to do a soft-field landing at full gross on a long runway. &lt;/p&gt;&#xA;" OwnerUserId="3504" LastActivityDate="2016-05-19T19:07:31.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27657" PostTypeId="1" AcceptedAnswerId="27682" CreationDate="2016-05-20T00:08:35.403" Score="7" ViewCount="2344" Body="&lt;p&gt;As a passenger on a commercial flight into Essaouira From London Luton a short while ago, I noticed the aircraft made several quite steep banked turns, all to left, very close to landing. When I say close I mean about five minutes before we touched the runway, and I'd estimate 600-1500 feet off the ground at most. It was possible to make out individual bushes in detail in the scrub. What was more concerning was that the terrain became undulating and was rising into rounded hills with a height difference of around 250 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sky was clear, and I don't remember any turbulence near the airport. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it normal to bank that close to the ground? I thought an approach was lined up further out and higher up.&lt;/p&gt;&#xA;" OwnerUserId="15008" LastEditorUserId="11215" LastEditDate="2018-10-31T15:54:01.817" LastActivityDate="2018-10-31T15:54:01.817" Title="Why would a commercial flight make banked turns five minutes before landing / low altitude?" Tags="&lt;approach&gt;&lt;altitude&gt;" AnswerCount="4" CommentCount="8" FavoriteCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="27658" PostTypeId="2" ParentId="27657" CreationDate="2016-05-20T01:14:43.460" Score="4" Body="&lt;p&gt;Given that the sky was clear and there are no charted visual approaches in the Moroccan Aeronautical Information Publication for Essaouira (GMMI) -- what I suspect happened was that ATC gave your flight a vector or vectors to a visual final approach after having them descend to the area Minimum Vectoring Altitude.  (The Minimum Vectoring Altitude for an area can be lower than the published procedure altitudes.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also: while &quot;normal&quot; approaches line up early, airspace or terrain constraints mean there are procedures that call for turns much lower and later than the vectoring your flight receieved.  Examples include the main instrument approaches to runway 19 at Reagan National (KDCA).&lt;/p&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2016-05-20T01:14:43.460" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27659" PostTypeId="2" ParentId="27657" CreationDate="2016-05-20T01:36:17.213" Score="8" Body="&lt;p&gt;Now, I'm not an ATP, but as a pilot I know that sometimes I (and commercial airlines) will make &quot;S&quot; turns on final for spacing.  There are minimum times between an aircraft taking off/landing and another aircraft landing behind them due to wake turbulence.  Instead of making the aircraft go-around (which would take quite a bit of time), they may be asked to slow down as much as safely possible and make the s-turns for spacing.&lt;/p&gt;&#xA;" OwnerUserId="15012" LastActivityDate="2016-05-20T01:36:17.213" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27660" PostTypeId="1" AcceptedAnswerId="27662" CreationDate="2016-05-20T04:41:50.857" Score="4" ViewCount="568" Body="&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;nofollow&quot;&gt;Wikipedia page for &lt;em&gt;Automatic Dependent Surveillance – Broadcast&lt;/em&gt; (ADS–B)&lt;/a&gt; explains that the aircraft surveillance technology is being phased-in around the world currently, with some due dates in 2017 and 2020 and so on. I see organizations like &lt;a href=&quot;https://flightaware.com/adsb/&quot; rel=&quot;nofollow&quot;&gt;FlightAware.com are deploying their own ADS-B receivers&lt;/a&gt; and are crowd-sourcing data from &lt;a href=&quot;https://flightaware.com/adsb/piaware/build&quot; rel=&quot;nofollow&quot;&gt;homemade receivers&lt;/a&gt; as well. That leads me to wonder…&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How many commercial airliners are currently equipped? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any reports or estimates by airline or by country/region? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also: Are private jets being equipped? Are small aircraft being equipped?&lt;/p&gt;&#xA;" OwnerUserId="2956" LastEditorUserId="2956" LastEditDate="2016-05-20T04:50:08.720" LastActivityDate="2016-05-21T02:24:43.100" Title="How many commercial jetliners are equipped with ADS–B?" Tags="&lt;ads-b&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27661" PostTypeId="2" ParentId="27603" CreationDate="2016-05-20T06:06:57.843" Score="2" Body="&lt;p&gt;I'm missing one thing mentioned in the answers. The point is: They say that the gravitational force and the lift force's vertical component have to be equal to make the plane fly levelled. This is not entirely true. The plane is also turning, which needs some force. Let's see how much it is, for a plane at $10\,{\rm km}$ flying $900\,\rm{km\,h^{-1}}$:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Gravity: $-mg = -m\cdot9.8\,{\rm m\, s^{-2}}$&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Force needed for turning: $-mv^2/r = -m\cdot (250\,{\rm m\,s^{-1})^2} / 6388000\,{\rm m}=-m\cdot0.00978\,{\rm m\, s^{-2}}$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;($m$ is the weight, $g$ is the gravitational acceleration, $v$ is the speed and $r$ is the turning radius)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So the force needed for turning is $1/1000$ of the gravitational force. This is negligible in the planes power and other settings, and also much smaller than any irregularities such as varying air density, wind speed etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conclusions: the adjustment for &quot;turning down&quot; is so little that it's negligible.&lt;/p&gt;&#xA;" OwnerUserId="802" LastEditorUserId="802" LastEditDate="2016-05-20T20:31:40.303" LastActivityDate="2016-05-20T20:31:40.303" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27662" PostTypeId="2" ParentId="27660" CreationDate="2016-05-20T07:42:40.500" Score="8" Body="&lt;p&gt;The majority of commercial airliners are currently equipped. I don't have the latest statistics, but for Europe over 80% of the airliners were equipped with 1090 Extended Squitter ADS-B two years ago. The percentage in the USA was similar but a bit lower. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;That doesn't mean that all those aircraft are compliant with the European rules that mandate ADS-B for these aircraft from 2020 onwards. To be compliant, the aircraft need to have ADS-B version 2 (EUROCAE ED-102A / RTCA DO-260B compliant transmitters) and the installation in the aircraft has to meet certain criteria. At this moment (May 2016) I estimate the percentage of rule compliant airliners to be less than 20%. I haven't run statistics on my own dataset for a while, I may update this figure over the summer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In Europe, all aircraft heavier than 5700 kg maximum take-off mass or a maximum cruise speed exceeding 250 knots true airspeed are subject to the ADS-B rule.&#xA;Therefore private jets and some small propeller aircraft will need to equip with ADS-B as well. In addition many people voluntary equip their aircraft with ADS-B; it is not uncommon to see ADS-B equipped gliders in Europe. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The situation in the US is a little different. The FAA mandate requires aircraft flying in certain airspaces to equip with ADS-B. In my view this makes more sense since it will prevent a mix of equipped and non-equipped flights in one airspace. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the USA, two types of ADS-B are allowed. The 1090 ES is required above 18 000 ft, below that altitude Universal Access Transceiver is also allowed. This causes all kinds of interoperability problems that can only be fixed at high cost.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA mandates aircraft in the 48 contiguous states (and D.C.) that operate in class A, B, or C airspace or class E airspace above 10 000ft (class E airspace below 2500 AGL excluded) to be ADS-B OUT equipped by January 1st, 2020. The mandate itself can be found &lt;a href=&quot;https://www.gpo.gov/fdsys/pkg/FR-2010-05-28/pdf/2010-12645.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; and the associated Advisory Circular (AC90-114) can be found &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2090-114.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means many more aircraft are subject to the rule. I have no recent information on what the implementation status is. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="8730" LastEditDate="2016-05-21T02:24:43.100" LastActivityDate="2016-05-21T02:24:43.100" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27664" PostTypeId="2" ParentId="2198" CreationDate="2016-05-20T13:58:37.453" Score="2" Body="&lt;p&gt;This service is already available for GA aircraft on VFR flight plans, using the consumer grade Spot Beacon.   &lt;a href=&quot;http://www.findmespot.com/en/index.php?cid=112&quot; rel=&quot;nofollow&quot;&gt;(&lt;strong&gt;&lt;em&gt;Link to Press Release&lt;/em&gt;&lt;/strong&gt;)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because Spot &lt;a href=&quot;http://www.findmespot.com/en/index.php?cid=108&quot; rel=&quot;nofollow&quot;&gt;covers most of the earth&lt;/a&gt;, I cannot see why it wouldn't be a generalized solution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The cost (at the GA level) is around \$100 for the device and about \$100 per year, so its quite reasonable.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The device is not covered by a TSO, so it is not certified for commercial use, and such a certification would be pricey and difficult.  Still, I think the technology is ready and has been demonstrated.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2016-05-20T14:28:07.730" LastActivityDate="2016-05-20T14:28:07.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27666" PostTypeId="1" CreationDate="2016-05-20T16:48:14.433" Score="7" ViewCount="2022" Body="&lt;p&gt;Are turn rate indicators calibrated to a certain speed? If they are, what speed are they calibrated to, and why aren't all the turn rate indicators calibrated for the same speed?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="34686" LastEditDate="2020-10-27T10:37:25.553" LastActivityDate="2020-10-31T06:19:40.057" Title="Are turn rate indicators calibrated to a certain speed? If so, what speed?" Tags="&lt;flight-instruments&gt;&lt;gyroscopic-instruments&gt;&lt;calibration&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="27667" PostTypeId="1" AcceptedAnswerId="27672" CreationDate="2016-05-20T17:06:36.610" Score="21" ViewCount="4413" Body="&lt;p&gt;I'm aware that there is a lot that goes into an aircraft accident investigation, so I understand that the investigations take a long time &lt;em&gt;for a reason&lt;/em&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what I don't know is what those reasons are.  I'm hoping someone with some familiarity can give a high level overview as to why aircraft accident investigations take so much time?&lt;/p&gt;&#xA;" OwnerUserId="511" LastEditorUserId="511" LastEditDate="2016-05-20T20:53:17.087" LastActivityDate="2016-05-21T20:57:03.143" Title="Why does it take months, sometimes years, for the BEA and NTSB to complete aviation accident investigations?" Tags="&lt;accident-investigation&gt;&lt;ntsb&gt;" AnswerCount="4" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27669" PostTypeId="2" ParentId="27666" CreationDate="2016-05-20T17:48:07.267" Score="15" Body="&lt;p&gt;&lt;strong&gt;They are not calibrated for a certain speed.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If by &quot;calibrated&quot;, you mean they deflect together / to the same side, then you're using the instruments wrong. The two instruments have are not linked to each other, they operate independently and they operate on different principles. They are located next to each other in the cockpit out of convenience.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;slip indicator&quot; is a ball in a U-shape tube. It tells you whether gravity (or experienced acceleration) is pointed down, or to the side. Period. It is as simple as that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &quot;turn coordinator&quot; (little white plane / white needle) indicates your yaw rate. It operates by using a spinning &lt;a href=&quot;https://en.wikipedia.org/wiki/Gyroscope&quot; rel=&quot;nofollow noreferrer&quot;&gt;gyro&lt;/a&gt;; the &lt;a href=&quot;https://en.wikipedia.org/wiki/Precession&quot; rel=&quot;nofollow noreferrer&quot;&gt;precession effect&lt;/a&gt; of yawing causes the gyro assembly to roll.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zkgHI.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zkgHI.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The roll is restricted by a spring, which is calibrated to indicate &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_rate_turn&quot; rel=&quot;nofollow noreferrer&quot;&gt;standard rate turn&lt;/a&gt; when the yaw rate is 3 degrees per second. The turn coordinator works &lt;em&gt;at any airspeed&lt;/em&gt; (part of the preflight check is to turn the plane while taxing and verify the turn coordinator works).&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2017-03-01T20:03:10.320" LastActivityDate="2017-03-01T20:03:10.320" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27670" PostTypeId="2" ParentId="27667" CreationDate="2016-05-20T18:00:07.283" Score="10" Body="&lt;p&gt;If you would like a little &quot;light-reading&quot; to answer the question.  Take a look at the &lt;a href=&quot;http://www.ntsb.gov/investigations/process/Documents/MajorInvestigationsManual.pdf&quot;&gt;NTSB investigation manual&lt;/a&gt; as well as the &lt;a href=&quot;http://www.ntsb.gov/about/Documents/MajorInvestigationsManualApp.pdf&quot;&gt;315 page appendix&lt;/a&gt; that goes with it.  Together they will give you some sense of the investigation process.  Just the time to read through that manual will take a while, let alone to perform the processes that it discusses.  &lt;/p&gt;&#xA;" OwnerUserId="4405" LastActivityDate="2016-05-20T18:00:07.283" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27671" PostTypeId="2" ParentId="27667" CreationDate="2016-05-20T18:26:10.337" Score="17" Body="&lt;p&gt;I have not done any aviation investigation (I am far from even qualifying for the job), but I will try to relate it to something I have experience with: research paper writing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A couple of similarities between both come to mind:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;strong&gt;You don't know what you're looking for.&lt;/strong&gt; You take a quick look at the big picture, pick your best guess (sometimes a wild guess), then dig deeper into that direction. If you're lucky, it works; usually it takes a few trials.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You need to call experts.&lt;/strong&gt; Even within the field of aviation, there are many experts who specialize only in subfields, e.g. materials, human factors, aerodynamics etc. If you need to analyze the inner workings of a component or system, often times you have to contact the manufacturer. They have to then contact their employees, who may delegate that work to someone in their department, then that person has to pack up and travel. And it's likely you need many experts like these during the investigation.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you suspect a bomb, you need an explosives expert.&lt;/li&gt;&#xA;&lt;li&gt;If you suspect the weather was abnormal, you need a meteorologist.&lt;/li&gt;&#xA;&lt;li&gt;If you suspect a structural failure, you need a materials expert.&lt;/li&gt;&#xA;&lt;li&gt;If you suspect a defect in a component, you need an engineer from the manufacturer.&lt;/li&gt;&#xA;&lt;li&gt;If you suspect pilot fatigue, you need a doctor who specializes in aviation.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You need to collect data&lt;/strong&gt;. You need to conduct experiments or examinations to collect data. You need to &lt;em&gt;design&lt;/em&gt; an experiment that fits your purpose. You need to set them up: apparatus, environment, users, everything. You need to do it scientifically. You need accurate measurements. Typical data I've seen in major accident reports include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Flight data recorder / transcript of cockpit voice recorder&lt;/em&gt;. If the blackbox was damaged, technicians will need more time to extract data.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Flight history&lt;/em&gt;. When did it take off? Which airway it was flying? Do radar tracks deviate from the FDR? What was the weather?&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Pilots' background&lt;/em&gt;. When did the captain get their license? When did he get training? Are there any failed checks in the past? Was the license &lt;em&gt;actually&lt;/em&gt; valid and not fake? &lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Interviews&lt;/em&gt;. Did the previous crew have problems with this plane? What did the mechanics do? How did the ground crew fuel the plane? What do the pilots who landed just before this plane say? What do friends of the pilot involved think about his flying ability? What about the controllers?&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Examinations&lt;/em&gt;. What was the position of the switches in the cockpit before impact? Did this debris come off because of metal fatigue? Are there signs of fuel leak? Did this break before impact, during impact, or during the post-crash fire?&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Experiments&lt;/em&gt;. Would putting a rubber tire before the engine inlet lead to an explosion? Would the wings oscillate at 30mph crosswind? The manufacturer says the strength of the valve should withstand 100psi. Is that true?&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You need to analyze.&lt;/strong&gt; There is a huge amount of data. Do you find any anomalies? Any trends? Any correlation? Was that an experimental error, or did you find something?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;em&gt;Is the scenario reproducible in the simulator?&lt;/em&gt; This is common for control surface issues / corrupted flight data in the blackbox / abnormal cockpit warnings recorded.&lt;/li&gt;&#xA;&lt;li&gt;&lt;em&gt;Was it possible for the crew to save the plane?&lt;/em&gt; Quite often, for controlled-flight-into-terrain accidents, the report would state something like &quot;if the pilot applied corrective action at or before the 13.7s mark, he would have cleared the trees by at least 200 feet&quot;.&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You need to coordinate.&lt;/strong&gt; Only the core investigators (those who get to decide the direction or conclusion of the investigation) have access to every piece of information. The others only get information related to their tasks. When necessary, the team would split up, e.g. two or three people investigate engine fire, another two or three study the charts and the flight path. You need meetings for the teams to present their findings and coordinate. Sometimes you would also need to coordinate with external parties:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;If you need to run simulator trials, you need find someone with a simulator and volunteer pilots.&lt;/li&gt;&#xA;&lt;li&gt;If you need aerial trials, you (likely) need special permission from the aviation authority and ATC, along with a plane and its pilots.&lt;/li&gt;&#xA;&lt;li&gt;If you suspect the airline's training program is a factor, you need to talk to the chief instructor. &lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;strong&gt;You need to prove&lt;/strong&gt;. One of the reasons why NTSB reports are so reputable, is that they carry out extensive analysis to prove that &lt;em&gt;every other possible scenario was not the case&lt;/em&gt;. They disprove every theory you can imagine, until you are left with nothing but the proposed cause of the incident.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;You need to write.&lt;/strong&gt; A decent research paper takes around a month just to write. You need to organize the content. You need to proofread for mistakes. A full investigation report is several times longer than a research paper.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="595" LastEditDate="2016-05-21T09:50:47.563" LastActivityDate="2016-05-21T09:50:47.563" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27672" PostTypeId="2" ParentId="27667" CreationDate="2016-05-20T18:42:29.087" Score="35" Body="&lt;p&gt;When it comes down to it, accident investigations involve lots of coordination between many different groups, companies, and agencies, often around the world. These groups may range from helpful and responsive to completely uncooperative.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Visiting the Site&lt;/strong&gt; - First there will be a team that heads to the incident site to collect information. If the site is easily accessible, this may be a fairly quick process. If the site is tough to access, or takes a while to find, this will of course take much longer. This is generally the part most visible to the public, but is only the tip of the iceberg in generating a useful report.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Research&lt;/strong&gt; - There is also a lot of research that must go on behind the scenes. Especially if a possible cause is not clear, investigators must look into many factors to rule out the options. This can be a lot of information and may involved many different groups around the world:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Previous maintenance done on the plane&lt;/li&gt;&#xA;&lt;li&gt;ATC and weather information about the flight&lt;/li&gt;&#xA;&lt;li&gt;Information about the crew, the passengers, and the cargo on the flight&lt;/li&gt;&#xA;&lt;li&gt;Many individuals may also be interviewed&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If any of this initial information provides clues as to possible causes of an accident, they will also be gathering information about related aircraft design and functions. This can be a lot of information and may involve working with many different groups. The process of narrowing the focus of the investigation may involve tracking down different leads which end up being irrelevant. It may take a lot of effort just for the report to end up saying &quot;X was not a factor.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Flight Recorders&lt;/strong&gt; - Gathering the flight recorder data is not always as simple as plugging it in and reading the data. If there is damage, extracting and repairing the memory may take time. The FDR data must be analyzed and &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1201.pdf&quot;&gt;it may take additional work to investigate and verify the parameters&lt;/a&gt;. The CVR must be read out and then transcribed. Transcription is also a long process, involving different parties to the investigation, and must be synchronized to ATC and FDR information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Analysis&lt;/strong&gt; - Once the information has been collected, it must all be analyzed. Investigators may need to contact and work with many different groups and experts to develop an understanding of parts and processes that took groups of engineers years to analyze and design. Components may need to be analyzed down to a microscopic level. This is generally the longest part of the process. Investigators may realize that they must go gather more information. This may involve running tests on equipment to recreate issues. It may take a lot of work to not only explain what failed, but also the reasons behind the failure and how it could be avoided in the future. Most reports will find issues in many different areas, including human factors, regulations, procedures, and aircraft design.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Report&lt;/strong&gt; - The investigators will eventually need to come to some conclusions among themselves. This must all be written up in a report. Some reports can be quite lengthy. If you've ever had to write something like this, you might know that writing the report can easily take much longer than the work that went into it. There will also be an opportunity for parties to the investigation to make comments and provide feedback before the report is released. This is where the investigators get to share the results of all their hard work, and it will be published to get picked apart by the whole world, so it's worth taking the time to get it right.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Law&lt;/strong&gt; - While most agencies like the NTSB focus on producing a factual report and not assigning blame, lawyers may also need to get involved. Investigations may involve dealing with proprietary or sensitive information, or groups that are reluctant to divulge information (see &quot;completely uncooperative&quot; above). Some accidents may involve criminal investigations as well, in which case organizations like the FBI may also be involved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Followup&lt;/strong&gt; - It's not even over after the report has been released. The agency will still need to follow up with regulatory agencies (like the FAA) about recommendations made in the reports and determine whether the responses are adequate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Additional Duties&lt;/strong&gt; - On top of all this, many investigators will not be working on one incident full time. Agencies like the BEA and NTSB investigate many smaller incidents as well. So imagine that at any given time, an agency may have many active investigations at different points in the above process. In the case of the NTSB, all of this is accomplished by about &lt;a href=&quot;http://www.ntsb.gov/about/reports/Documents/NTSB_FY2017_Budget.pdf&quot;&gt;400 people with a budget of around $100 million per year&lt;/a&gt;. While aviation safety is the largest part of this with about 130 employees, the NTSB also investigates highway, marine, and railroad/pipeline/hazardous material incidents. Employees also spend time on other things such as educating the public about safety issues, looking for ways to improve safety, and producing &lt;a href=&quot;http://www.ntsb.gov/investigations/AccidentReports/Pages/ASR1602.aspx&quot;&gt;additional types of reports&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-05-20T20:47:31.650" LastActivityDate="2016-05-20T20:47:31.650" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27673" PostTypeId="2" ParentId="27657" CreationDate="2016-05-20T19:05:58.567" Score="3" Body="&lt;p&gt;I don't know the type of aircraft but most probably you were not so close to ground. In normal stabilised approach it would be approximately 1:30 minutes from 1500 ft to ground. In old days we were making timing approaches for defined ground speeds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So Second part : Airliners don't make step turns unless otherwise there is emergency. Bank limit for turn 33 degrees for airbus and after that you need to push even more to 67 degrees without slip control. If you make a step turn so close to ground you need to apply a lot of thrust due to load factor to achieve level flight. Also you definitely feel the turn due to increased G. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My option, you may have seen a nice circle to land operation, wind condition may not be the best option for approach runway, either pilot or ATC may ask to circle another runway which is close to ground, but again in safe altitude. 500 ft above the ground an airliner must be aligned and stabilised, unless safety issues. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Above requirements are for conducting a safe flight, depends on carrier and pilot they may have push limits more if you think that you were closer than 500 ft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Especially in Africa, there are many non-precision approaches and you may need to make approach to one runway and circle to land another one. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I could not find official charts of ESU. Never been there but hope it helps. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cheers,&lt;/p&gt;&#xA;" OwnerUserId="9809" LastActivityDate="2016-05-20T19:05:58.567" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27674" PostTypeId="2" ParentId="27646" CreationDate="2016-05-20T19:19:02.827" Score="1" Body="&lt;p&gt;There is no such procedure for making these turns, however you can make orbits to lose altitude which is basically 360 turns. You may need it when you are very high and need to lose altitude. Let say you lost engines, executing powerless flight and you have very good option for airport just below you. So you can come on top the airport and begin orbiting. Also in military there is pill off manoeuvre making 360 to land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For this crash, I think there is a total loss of control associated with electrical fire after examining ACARS messages. You can find the link here :&#xA;&lt;a href=&quot;http://avherald.com/h?article=4987fb09&amp;amp;opt=7168&quot; rel=&quot;nofollow&quot;&gt;http://avherald.com/h?article=4987fb09&amp;amp;opt=7168&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;May be detailed but nice to read all. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Bests,&lt;/p&gt;&#xA;" OwnerUserId="9809" LastActivityDate="2016-05-20T19:19:02.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27677" PostTypeId="2" ParentId="27603" CreationDate="2016-05-20T22:02:05.017" Score="0" Body="&lt;p&gt;I think that the aircraft should fly straight, not following the Earth curvature if nothing is done. This means, it should have a slight tendency to raise up but this may be only noticeable when it flies half way around the globe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This effect may be much smaller than other factors that would alter the altitude. Anyway, if the aircraft is set to fly at some fixed altitude, it would compensate for the Earth curvature as well without doing anything special.&lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2020-03-25T16:00:15.780" LastActivityDate="2020-03-25T16:00:15.780" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27678" PostTypeId="2" ParentId="27603" CreationDate="2016-05-20T22:56:06.463" Score="1" Body="&lt;p&gt;For reasons that are explained in several other answers, there is no need&#xA;for an aircraft pilot to make any special calculations or adjustments of&#xA;the controls in order to &quot;drop&quot; the aircraft eight inches per mile&#xA;and thereby follow the Earth's curvature.&#xA;Instead what pilots actually &lt;em&gt;do&lt;/em&gt; is to keep the aircraft at a constant&#xA;pressure altitude, which (approximately) follows the curvature of the earth.&#xA;The path followed by an aircraft in this fashion actually can rise or&#xA;fall quite a bit due to weather-induced variations in pressure, so it's&#xA;not guaranteed to drop 8 inches each and every time the aircraft flies a&#xA;mile, but it will follow the curve of the Earth much more closely than it&#xA;follows a straight line over any long-distance flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer to the first part of your question is, &lt;em&gt;yes, pilots do&#xA;adjust the aircraft's flight path to allow for the curvature of the Earth,&lt;/em&gt;&#xA;and this is how they do it.&#xA;There is no &lt;em&gt;explicit&lt;/em&gt; &quot;adjustment for curvature&quot; term in the pilots'&#xA;(or autopilots') calculations, however, because they&#xA;keep the aircraft on the desired (curved) path by observing the&#xA;pressure altitude, much like the&#xA;way you would keep an automobile in its lane on a highway&#xA;by observing the lane markers,&#xA;which does not require you to know anything about the radius of&#xA;curvature of each curve the highway engineers laid out.&#xA;If the curve is gentle enough you might not even notice that &#xA;the road is curved, yet you would still be following it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A notable difference between highway lanes and the altitude of an aircraft,&#xA;however, is that the aircraft does not have the &lt;em&gt;ability&lt;/em&gt; to fly above&#xA;a certain altitude at a certain setting of the controls, due to the&#xA;low density of air at higher altitudes--so at higher altitudes the&#xA;aircraft will tend to descend--whereas at much lower altitudes&#xA;the aircraft's engines will generate more than enough power to keep the&#xA;aircraft aloft and so the aircraft will tend to climb.&#xA;The physical properties of the atmosphere and the aircraft therefore&#xA;tend to deflect the aircraft along a path that (approximately)&#xA;follows the curve of the Earth, and they absolutely prevent the aircraft&#xA;from continuing along a straight tangent line into outer space.&#xA;A large part (one might say the most important part) of how pilots make the aircraft stay at a given pressure altitude is by adjusting the &quot;trim&quot; of the aircraft (including throttle) in order to make it tend to fly at the&#xA;desired altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for the Earth's rotation, since the atmosphere generally rotates along with the rest of the Earth, and aircraft fly in the atmosphere, the aircraft do not have to fly faster or slower to overcome the Earth's rotation, any&#xA;more than you have to be able to run 500 mph in order to make your way&#xA;from the aft restroom forward to your seat.&#xA;(Some bits of the atmosphere do sometimes go a little faster than the Earth's rotation, sometimes a little slower, depending on which way the wind is blowing at each place; pilots &lt;em&gt;do&lt;/em&gt; to account for the wind in&#xA;order to fly the desired path over the ground and to know how long it&#xA;will take to arrive.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the other hand, pilots very much &lt;em&gt;do&lt;/em&gt; have to take the curvature of the earth into account when planning the &lt;em&gt;lateral&lt;/em&gt; direction in which to fly.&#xA;For example, to fly from New York to London, the shortest path (fewest miles over the ground or water) heads out of New York on a course of about 51.4 degrees. The return flight starts out toward New York on a course of about 288 degrees.&#xA;Similarly, from London to Tenerife is a course of 213.5 degrees, 23.1 returning, and from Tenerife to New York is 300.5 degrees, 85.8 returning.&#xA;If you take those three flight paths as the three sides of a triangle,&#xA;it has angles of 34.4 degrees at New York, 74.5 degrees at London,&#xA;and 82.6 degrees at Tenerife, which adds up to 191.5 degrees, &#xA;which is impossible for any triangle plotted on a flat plane.&#xA;Pilots and other people who plan the routes of aircraft do so by&#xA;calculations (nowadays generally done in software) that take into account the approximately spherical shape of&#xA;the Earth to do so (and nowadays even take into account the few miles'&#xA;difference between the diameter of the Earth measured from pole to pole&#xA;and the diameter measured across the equator).&lt;/p&gt;&#xA;" OwnerUserId="3831" LastEditorUserId="3831" LastEditDate="2016-05-21T14:40:30.833" LastActivityDate="2016-05-21T14:40:30.833" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27682" PostTypeId="2" ParentId="27657" CreationDate="2016-05-21T04:32:09.547" Score="18" Body="&lt;p&gt;As denizhanedeer said, it was a circling approach. There is only one charted IFR approach to ESU. It comes in from the northwest and would line up for a straight-in approach to runway 16. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WOst2.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WOst2.jpg&quot; alt=&quot;ESU approach plate&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Depending on the wind the pilot may have needed runway 34 (same runway from the opposite end) so they would circle around to line up with it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This flight did just that. (It might even be your actual flight, Easyjet 2039 on 5/17/2016) It did a short hold at the final approach fix to lose altitude then circled to land on runway 34. It landed at 4:09 UTC. It did the first left turn at 4:06 and 1850 ft. The image here shows it during the second turn at 4:07 and 1475 feet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eDY7a.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eDY7a.jpg&quot; alt=&quot;U22039 5/17/2016&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The altitudes given are MSL. The terrain rises pretty quickly there. I'm guesstimating from some topo maps that at the area of the turns it rises to 175-200 feet. So 1475 ft MSL would be as low as 1275 ft above ground level. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-05-21T04:46:59.243" LastActivityDate="2016-05-21T04:46:59.243" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27683" PostTypeId="2" ParentId="27590" CreationDate="2016-05-21T07:06:57.387" Score="0" Body="&lt;p&gt;Generally, no. However in the Piper J-3 cub.. just fly upside down for a few minutes (you'll then be a glider unless you have an inverted fuel and oil system).  Plenty of fuel will drain out around the metal wire which is your fuel gage. :)&lt;/p&gt;&#xA;" OwnerUserId="15012" LastActivityDate="2016-05-21T07:06:57.387" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27684" PostTypeId="1" CreationDate="2016-05-21T07:32:56.790" Score="1" ViewCount="62" Body="&lt;p&gt;With today's technology, why are voice recordings not transmitted, saved somewhere in case a disaster does happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's say a plane goes missing, they can spend a long time trying to salvage the black box, thus could take years to find out the real cause of the problem. Surely if the data was transmitted, stored somewhere, the investigators could then use this information to clearly determine the cause and highlight any technical failure to help prevent such things happening again.&lt;/p&gt;&#xA;" OwnerUserId="10007" LastEditorUserId="595" LastEditDate="2016-05-21T09:18:55.940" LastActivityDate="2016-05-21T09:18:55.940" Title="Why are voice recordings stored and not transmitted?" Tags="&lt;commercial-aviation&gt;" AnswerCount="0" CommentCount="2" ClosedDate="2016-05-21T11:15:10.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="27685" PostTypeId="1" AcceptedAnswerId="27750" CreationDate="2016-05-21T08:23:15.320" Score="2" ViewCount="509" Body="&lt;p&gt;Surely, airline crews must have manuals/apps by which they calculate the (minimum) amount of refueling before departure to a given destination. I have been looking online for such sources, with zero hits.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Specifically, I'm intersted in such free manuals/apps for the Airbus A318...A321 and Boeing B737 families.&lt;/p&gt;&#xA;" OwnerUserId="15036" LastEditorUserId="19" LastEditDate="2016-07-06T16:05:41.483" LastActivityDate="2016-07-06T16:05:41.483" Title="Where can I find (online) manuals for refueling A320/B737 for a given destination?" Tags="&lt;airline-operations&gt;&lt;boeing-737&gt;&lt;airbus-a320&gt;&lt;refueling&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27686" PostTypeId="1" AcceptedAnswerId="27688" CreationDate="2016-05-21T16:08:58.730" Score="-2" ViewCount="20668" Body="&lt;p&gt;I was playing extreme landings pro with failure enabled but i've encountered a bunch of alarm types that does not in the tutorials such as tires etc. &#xA;What are all alarm types and workarunds in extreme landing. I couldn't find anywhere.&lt;/p&gt;&#xA;" OwnerUserId="15043" LastActivityDate="2016-05-21T16:26:51.337" Title="Extreme landings alarm types" Tags="&lt;flight-simulator&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-05-21T16:32:05.067" ContentLicense="CC BY-SA 3.0" />
  <row Id="27688" PostTypeId="2" ParentId="27686" CreationDate="2016-05-21T16:26:51.337" Score="2" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;&quot;Tire Alarm&quot; would be that the tires do not have enough pressure in them. You deal with that one by coming in at a lower speed. Once you land, you would have to compensate for whatever direction the airplane lurches in.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For the airspeed and altimeter alarms, just use your memory of about how a certain altitude and speed looks like. For airspeed, the engine sound might also help.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For any of the braking alarms (brake, air brake, thrust reverse) just go in a little slower and lower and prepare for a longer landing roll.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Flaps alarm. Just fly and land normally, not too much of a problem with that.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;ASY and No Fuel (for certain engines) alarms would best be counteracted by just using more throttle than you normally would since a number of engines would not be working.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Note: Tire, airspeed, altimeter, braking, and flaps alarms can't be &quot;fixed&quot; from your controls. The ASY and No Fuel may be able to be fixed by transferring fuel over to the empty tank. However, in certain alarms, the fuel just leaves immediately, so forgo trying to transfer fuel over. You also want to keep your attention of your flying or you might smash into the ground while trying to take care of your alarms.&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-05-21T16:26:51.337" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27689" PostTypeId="1" AcceptedAnswerId="27710" CreationDate="2016-05-21T20:14:19.537" Score="19" ViewCount="31722" Body="&lt;p&gt;How does the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tactical_air_navigation_system&quot; rel=&quot;noreferrer&quot;&gt;Tactical Air Navigation&lt;/a&gt; (TACAN) system work? How is it different from the &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;noreferrer&quot;&gt;VHF Omnidirectional Range&lt;/a&gt; (VOR) system? Please explain in the simplest possible way. &lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="15311" LastEditDate="2017-12-27T20:05:20.073" LastActivityDate="2020-10-28T19:39:11.540" Title="How does TACAN work?" Tags="&lt;navigation&gt;&lt;avionics&gt;&lt;radio-navigation&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27690" PostTypeId="2" ParentId="27689" CreationDate="2016-05-21T20:32:42.727" Score="5" Body="&lt;p&gt;Well, the short answer is that it operates in the same way as VOR except it uses UHF instead of VHF - and is therefore less subject to distortion - and always incorporates DME so a range and bearing are both given.  VOR/DME is the civilian equivalent.&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="595" LastEditDate="2016-05-22T06:26:15.727" LastActivityDate="2016-05-22T06:26:15.727" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27691" PostTypeId="2" ParentId="27667" CreationDate="2016-05-21T20:57:03.143" Score="1" Body="&lt;p&gt;This is not a canonical answer to this Q as asked.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But I will add: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a slow investigation is not a bad thing, thorough is good&lt;/li&gt;&#xA;&lt;li&gt;a &lt;em&gt;completed&lt;/em&gt; investigation is just one part of the value in the holistic process of aviation safety&lt;/li&gt;&#xA;&lt;li&gt;when investigators find something obviously wrong, corrective actions are sent out immediately to the aviation community in various directives. This often happens &lt;em&gt;before an investigation is complete&lt;/em&gt; (I'm not an aviation professional, so someone may have good examples of this)&lt;/li&gt;&#xA;&lt;li&gt;the most valuable part of this process is the accuracy of the investigation---and how good the corrective actions address the root cause of the accident&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14549" LastActivityDate="2016-05-21T20:57:03.143" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27693" PostTypeId="1" CreationDate="2016-05-21T21:12:42.943" Score="5" ViewCount="18310" Body="&lt;p&gt;First of all, we all know what IAS is and if not for some people you can follow &lt;a href=&quot;https://aviation.stackexchange.com/questions/7500/why-are-planes-slower-at-higher-altitudes/7502#7502&quot;&gt;this link&lt;/a&gt; to read the basics about stall and the differents speeds. So we also know that our TAS/ Mach number will increase with increasing altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Let's assume that our IAS stall speed is 100kts at sea level, what will be our IAS stall speed at 30 000 feet with exactly the same aircraft ? (Assume ISA atmosphere)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Everyone would be tempted to answer that it doesn't change, right? but what about the low speed buffet in this picture ?&lt;a href=&quot;https://i.stack.imgur.com/Nzrms.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Nzrms.jpg&quot; alt=&quot;low and high speed buffet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We agree in saying that the low speed buffet here is not the same as the one at sea level but look, our IAS/CAS stall speed has a higher value now. Maybe that it's a representative value of IAS/CAS calculated by the Air Data Computer from an EAS but still, our IAS stall speed has rised.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We can also keep it simple and think about it for a non pressurized single engine aircraft. I don't need an exact value but I would love to have a logic and smart answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to be very basic but when we correctly think about it we can find ourself a little bit confused.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;For me, the answer is : The IAS stall speed will increases&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="7411" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-05-22T15:06:18.780" Title="How does the IAS stall speed vary with increasing altitude?" Tags="&lt;aerodynamics&gt;&lt;airspeed&gt;&lt;stall&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27694" PostTypeId="2" ParentId="27693" CreationDate="2016-05-21T22:12:07.517" Score="8" Body="&lt;p&gt;Airplanes do not stall at the same indicated speed or even at the same angle of attack - &lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375#6375&quot;&gt;it all depends on circumstances&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The angle of attack dependency is discussed &lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620#3620&quot;&gt;here&lt;/a&gt;. An increased pitch rate can push the stall angle of attack 50% higher than what the stall angle of attack is in stationary conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next big factor is the Mach number. When increasing the angle of attack, the flow around the airfoil's nose will develop a suction peak. This suction is equivalent to higher local speed, and if the critical speed (when local flow speed equals the local speed of sound) is exceeded, the flow past the suction peak will &lt;a href=&quot;https://aviation.stackexchange.com/questions/8846/what-happens-when-an-aircraft-breaks-the-sound-barrier/8848#8848&quot;&gt;no longer behave similarly&lt;/a&gt; to the flow at the same angle of attack but a lower flight Mach number. Let's just say that the local Mach number in the suction peak has a strong influence on the stall angle of attack, and flying at a higher Mach number lowers the stall angle of attack, &lt;a href=&quot;https://aviation.stackexchange.com/questions/8016/what-is-a-high-speed-stall/8020#8020&quot;&gt;sometimes dramatically&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Increasing altitude will raise the flight Mach number in two ways:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;The reducing density means you need to speed up to fly at the same dynamic pressure, and&lt;/li&gt;&#xA;&lt;li&gt;the &lt;a href=&quot;https://en.wikipedia.org/wiki/Lapse_rate&quot; rel=&quot;nofollow noreferrer&quot;&gt;atmospheric lapse rate&lt;/a&gt; decreases the speed of sound in air.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Both effects conspire to reduce the stall angle of attack at 30.000 ft to a value quite a bit below that at sea level. Details depend on the airfoil and &lt;a href=&quot;https://aviation.stackexchange.com/questions/14236/is-there-always-a-stall-if-you-exceed-a-specific-angle-of-attack/14257#14257&quot;&gt;specifically on its nose radius&lt;/a&gt; and wing loading.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only very light aircraft will not be affected by the change in Mach number, but even here the stall angle of attack at altitude is lower than at sea level due to the &lt;a href=&quot;https://aviation.stackexchange.com/questions/24641/drag-as-a-function-of-altitude/24644#24644&quot;&gt;reduction of the flow's Reynolds number&lt;/a&gt; with increasing altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, the indicated stall speed goes up with increasing altitude for a variety of reasons and does so nonlinearly. The magnitude of the change depends on a multitude of details.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-05-21T22:12:07.517" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27697" PostTypeId="2" ParentId="27642" CreationDate="2016-05-21T22:41:57.770" Score="1" Body="&lt;p&gt;It would appear that there is a standby battery controller PCB.  It's important to note that &lt;code&gt;M BUS VOLTS&lt;/code&gt; are read off the crossfeed bus as there is no main bus.  The label is a bit misleading in my opinion.  It's been awhile since I have flown a G1000 C172 but if I remember correctly you should not see 1.5volts on the &lt;code&gt;M BUS VOLTS&lt;/code&gt; but zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The checklist is verifying the PCB box doesn't have a fault that will allow the standby battery to power more than just the essential bus.  Unfortunately, the POH is silent as to why this check is done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TKo77.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TKo77.png&quot; alt=&quot;C172 Standby Battery Electrical System&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-05-21T22:41:57.770" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27699" PostTypeId="1" AcceptedAnswerId="27703" CreationDate="2016-05-21T22:48:44.853" Score="6" ViewCount="3856" Body="&lt;p&gt;When cruising at high altitude, a fixed-wing aircraft has less margin for adjusting its speed, due to the convergence of the &lt;a href=&quot;https://en.wikipedia.org/wiki/Stall_%28fluid_mechanics%29#Speed&quot; rel=&quot;noreferrer&quot;&gt;stall &quot;speed&quot;&lt;/a&gt; and the overspeed limit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/0GAae.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0GAae.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If and aircraft has to be separated to prevent it to get close to a preceding, and ATCO asks to the second aircraft to slow down a bit, this may result in speed lower than the stall speed. On the other hand asking it to descend to a lower level may be costly due to fuel rate increasing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the usual way to fulfill such separation need?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-05-22T02:18:36.413" LastActivityDate="2016-05-22T13:25:38.307" Title="How are aircraft separated at high altitude?" Tags="&lt;air-traffic-control&gt;&lt;separation&gt;&lt;high-altitude&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27700" PostTypeId="2" ParentId="27699" CreationDate="2016-05-21T23:11:44.617" Score="3" Body="&lt;p&gt;The usual way is to change altitude. Going above or below the other plane. The TCAS/ACAS system (the last automated warning to avoid collisions) will give a ascend or descend command to the pilots. The minimal vertical separation between such passing plane should be 1000 ft. Typically it will be 2000 ft because the altitudes are allocated per direction (odd go one way even go the other).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also there isn't just one altitude airliners fly at. If 2 planes have to follow the same path they will be assigned different altitudes. It's also possible for the planes to be offset laterally by a dozen miles. ATC will in general &lt;strong&gt;never&lt;/strong&gt; put 2 planes close enough that they could crash. If they did then something is horribly wrong and should be investigated. &lt;a href=&quot;https://aviation.stackexchange.com/q/2806/609&quot;&gt;The rules about how close planes are allowed to be is answer in detail here.&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not to mention when the choice is between a potential crash or higher fuel cost the answer is always more fuel. There is no way anyone can justify saving fuel at the risk of collisions.&lt;/p&gt;&#xA;" OwnerUserId="609" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-05-21T23:11:44.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27701" PostTypeId="1" AcceptedAnswerId="29060" CreationDate="2016-05-22T01:10:02.983" Score="25" ViewCount="6586" Body="&lt;p&gt;I know &lt;a href=&quot;https://wikipedia.org/wiki/Scimitar_propeller&quot;&gt;scimitar propellers&lt;/a&gt; are used to reduce noise, but what is their downside? There has to be one, considering most propellers don't use that shape.&lt;/p&gt;&#xA;" OwnerUserId="14683" LastEditorUserId="4095" LastEditDate="2016-05-22T12:07:15.387" LastActivityDate="2021-03-20T00:18:04.130" Title="What are the pros and cons of scimitar propellers?" Tags="&lt;propeller&gt;" AnswerCount="2" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27703" PostTypeId="2" ParentId="27699" CreationDate="2016-05-22T05:45:17.927" Score="14" Body="&lt;p&gt;First of all, there is no such thing as a stall &lt;em&gt;speed&lt;/em&gt;, but that is a topic of its own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATC system has numerous ways of dealing with keeping aircraft separated, even at high levels. Let me try to summarize some of the most important ones, starting with the planning that happens when planes are still at the ground at their departure airport, working our way towards what happens when they do get (too) close.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft flying en-route will follow pre-defined routes (known as airways or RNAV-routes). Airways are like highways in the sky, and ensure that air traffic will fly in predictable patterns. This makes it a relatively simple task of predicting potential conflicts (a conflict in this denotes a situation where two or more aircraft get closer than the prescribed separation minima), because every flight will send a flight plan in advance, detailing the planner route, level and speed to fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to just specifying lateral paths, airways also have vertical restrictions. This means that, when following a certain airways, you have to be flying in a certain range of vertical levels. It is quite typical for airways to limit traffic to fly at either “even” or “odd” levels. An even level in this case could be 34,000 feet, 36,000 feet, 38,000 feet and so on, while an odd level could be 33,000 feet, 35,000 feet etc. The general rule in most parts of the world is that airways going east will force traffic to fly odd levels, while airways going west will force traffic to fly even levels. This acts as a fall back procedures, which in principle means that two aircraft flying in opposite directions (one heading west, the other east) will never fly at the same level. Of course, it is easy to realise that this rule cannot cover every potential conflict.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We have now looked at some of the permanent infrastructure in the sky, but let’s zoom in further and look at the tactical aspect of flight planning, specifically, air traffic control.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Air traffic controllers, whose job is it to “maintain a safe and expeditious flow of air traffic”, use various means of technology to keep aircraft in the sky separated. In many parts of the world, their job is achieved by processing large amounts of information received in real time about air traffic using radar technology, and communicating with planes using radio. In places where no radar coverage exists, such as over large oceans, only radio is used. If no radar is available, pilots have to periodically call up on the radio and make a detailed position report, stating the location, level, speed and planned route of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using either radar or pilot position reports, air traffic controllers will predict potential conflicts and try to solve them. (This is really where the essence of your question will be answered).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a few different separation &lt;em&gt;minima&lt;/em&gt;. For the sake of simplifying the answer slightly, let’s assume we are working with only three:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;vertical separation (the vertical space required between two aircraft who pass each other at (almost) the same position&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;horizontal separation (the horizontal distance required between two aircraft passing each other at the same, or near the same level)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;time based separation (the minimum time required between aircraft following the same route, at the same level)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The vertical separation minima is generally 2,000 feet, however, as aircraft altimeters and radars have gotten more accurate, this has been reduced to 1,000 feet in many areas of the world (called RVSM airspace). Considering the fact that most commercial aircraft cruise in a level band between 30,000 feet and 40,000 feet, this gives you 10 different levels to work with (30,000, 31,000, 32,000 and so on). That actually means, that using vertical separation alone, it is possible to have 10 different aircraft at the same position, at the same time, while they are still separated.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, forcing an aircraft to fly at a non-optimum level is not the perfect solution in terms of fuel efficiency, but it can often be the lesser evil (as opposed to forcing speed changes etc.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Horizontal separation is achieved by (temporarily) changing aircraft routes. This might sound like a big deal, but in fact, potential conflicts are usually detected early enough that only very small adjustments are required. For two aircraft on intersecting tracks, if you detect the conflict between them 10-15 minutes in advance, it will often be enough to instruct either of the aircraft to adjust their heading by as little as 5 degrees to prevent the conflict. Once they are passed, you simply instruct them to return to their planned routes. This will only result in marginally longer flight paths, and so will only cause a small impact on fuel consumption.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Time based separation using speed control is probably the last resort in most cases. Instructing an aircraft to change it speed for a long period can have a serious impact on fuel efficiency. However, there is no need to worry about aircraft being forced to slow down enough to risk a stall (or speed up enough to risk damage to the aircraft). For starters, the pilot would never accept such instructions from air traffic control, and ATC would have to come up with another plan. In addition, air traffic controllers have been trained thoroughly, and are well aware of the performance limitations of different aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As with heading adjustments however, it might surprise you how little it takes to ensure separation using speed control. This is because most modern airliners actually fly at very similar speeds (usually between 75% and 85% the speed of sound). Changing the speed of an aircraft by just 1% will have a huge impact over a long distance, such as a flight across the North Atlantic Ocean. And so, as with levels, where in principle you have around 10 usable levels, considering 1,000 feet minimum vertical separation, you might also have about 10 different speeds to work with.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, speed control is a very efficient way of maintaining separation that already exists (e.g. two aircraft following each other on the same route, at the same level), because instructing them to fly at the same speed will ensure that the latter aircraft never catches up with the former. Horizontal and vertical separation can be applied when separation needs to be established, for example between aircraft on intersecting or opposite routes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, let’s briefly discuss what happens if the system fails. That is, if air traffic control, for one reason or the other, fails to provide the required separation between two aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All modern commercial aircraft are equipped with airborne collision avoidance systems (ACAS), the most common form being the TCAS. TCAS equipment of two different aircraft in proximity to each other communicate directly to determine a) if there is going to be a conflict and b) how to best solve it. I won’t go into details here, but basically, if two aircraft are predicted to get too close, the TCAS systems will work out how to solve the conflict, typically by instructing one aircrew to descend while instructing the other one to climb. The fact that the TCAS systems communicate ensures that the same instruction is not issues to both different aircrews (imagine the airplanes flying toward each other at the same level, both being instructed to climb …). If the TCAS goes off, all instructions received from the TCAS system takes precedence over air traffic control instructions (much like air traffic control instructions take precedence over the general airways rules we covered earlier).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to sum it all up – aircraft separation comes down to planning. If it is predicted, based on flight plans received from hundreds of different aircraft, that a certain route or level will be very busy for a certain period of time, then the system will simply not allow more aircraft to fly this way. They will be re-routed or their planned level changed, even before they leave the gate (allowing them to bring extra fuel, if required, to fly a slightly longer route or at a non-optimum level). Once in the air, air traffic control will make use of vertical, horizontal and time based separation, and, if all else fails, on-board computer systems will ensure that no collisions actually occur.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Edit:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A few references for further reading:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Mid-Air_Collision&quot; rel=&quot;noreferrer&quot;&gt;Mid-Air Collision&lt;/a&gt; - On the consequences of losses of separation, and how to prevent them&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Conflict_Detection_with_Adjacent_Sectors&quot; rel=&quot;noreferrer&quot;&gt;Conflict Detection&lt;/a&gt; - On detecting potential conflicts in the ATC system&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/ATM_Sector_Management&quot; rel=&quot;noreferrer&quot;&gt;ATM Sector Management&lt;/a&gt; - On predicting capacity and responding to demand in the ATC infrastructure&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Flight_Plan_Filling&quot; rel=&quot;noreferrer&quot;&gt;Flight Plan Filling&lt;/a&gt; - On ATC flight plans and their content&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://xn.ivao.aero/ops/doc?view=download&amp;amp;id=7&quot; rel=&quot;noreferrer&quot;&gt;Guidelines for providing Radar Separation&lt;/a&gt; - A few example calculations&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Airborne_Collision_Avoidance_System_%28ACAS%29&quot; rel=&quot;noreferrer&quot;&gt;Airborne Collision Avoidance System (ACAS)&lt;/a&gt; - On ACAS, the last resort, when all else fails&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.skybrary.aero/index.php/Reduced_Vertical_Separation_Minima_%28RVSM%29&quot; rel=&quot;noreferrer&quot;&gt;Reduced Vertical Separation Minima (RVSM)&lt;/a&gt; - On the parts of airspace where the minimum vertical separation is reduced from 2,000 feet to 1,000 feet&lt;/p&gt;&#xA;" OwnerUserId="14957" LastEditorUserId="14957" LastEditDate="2016-05-22T13:25:38.307" LastActivityDate="2016-05-22T13:25:38.307" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27704" PostTypeId="2" ParentId="13151" CreationDate="2016-05-22T06:07:42.710" Score="2" Body="&lt;p&gt;Most of the answers are based on the US system, so let me give a very brief explination of how ATC training generally works in Europe.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Overall, you will not get accepted into the training programme unless there is a job for you in the other end. This means that the selection rounds prior to starting training is not just a matter of being fit for training - it also includes a job interview.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Many European countries make use of the First European Air Traffic Controller Selection Test (FEAST), which is a standardized, computer-based test used to evaluate potential ATCO trainees.&#xA;FEAST is used to assess your cognitive and mental skills such as IQ, working under time pressure, multi-tasking, logical planning, mathematics etc. etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you pass the FEAST tests (there are two of them), you will be invited to the job interview, which is a pretty standard interview. Following the interview, if you are among the few lucky ones, you will have to undergo a medical examination and security clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you make it this far, you can start the actual education.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Training to become an ATCO takes about 3 years. The first half is part class-room, part simulator training, focusing on the huge amount of theoretical material you have to know as an air traffic controller. You will find many topics resemble those of pilot training: air law, radio communication, human factors and performance etc., but there are also more technical classes that deal directly with air traffic management.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second half of the education consists of on-the-job-training (OJT). During this period, you will handle real air traffic in a real environment, under the supervision of an instructor, who will brief, de-brief and generally assist you. You will learn to apply your theoretical knowledge in practise, and get familiar with the airspace and local procedures of the facility where you will end up working.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, during both the first and second half of education, you will have to take tests and exams to ensure you are keeping up with the goals and requirements.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then finally, after about three years, you will walk into your familiar training facility, but the instructor will be gone, and you just get on with it . . .&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-05-22T06:07:42.710" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27705" PostTypeId="2" ParentId="27693" CreationDate="2016-05-22T07:25:25.327" Score="-1" Body="&lt;p&gt;Vstall is measured as a true airspeed, it increases approximately 1% for every thousand feet increase in altitude.&#xA;100KTS its sea level - 110 KTS at 10000 feet&#xA;TAS increases 2% per thousand feet for any given IAS.&#xA;110 KTS TAS at 10000 feet  = 92 kts&#xA;Thus, Vstall TAS increases, IAS decreases&lt;/p&gt;&#xA;" OwnerUserId="15057" LastActivityDate="2016-05-22T07:25:25.327" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27706" PostTypeId="1" AcceptedAnswerId="27713" CreationDate="2016-05-22T08:47:24.403" Score="6" ViewCount="2530" Body="&lt;p&gt;I read, not only on this site, that the &lt;em&gt;stall speed&lt;/em&gt; of an airfoil doesn't exist, and I usually make the effort to stay away from this expression.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While an airfoil can stall at any airspeed, it's clear that the stall speed refers to the airspeed at which the stall occurs in an horizontal 1G flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/s55JP.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/s55JP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Stall speeds for B747-200 (n=1). (&lt;a href=&quot;http://home.anadolu.edu.tr/~mcavcar/common/Stall.pdf&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This speed is the lowest one that can generate a vertical component of lift equal to the weight with the airfoil at its stall angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would compare this implicit assumption with the maximum airspeed of an aircraft: It's clear we are assuming at least an horizontal flight and a standard atmosphere, etc, else this speed can be anything too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So what's wrong with this definition of the &quot;stall speed&quot;? Is the stall speed defined in the aerodynamics field?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example of use: &lt;a href=&quot;http://home.anadolu.edu.tr/~mcavcar/common/Stall.pdf&quot; rel=&quot;noreferrer&quot;&gt;Stall Speed&lt;/a&gt; (Dr. Mustafa Cavcar).&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-05-22T08:52:49.900" LastActivityDate="2019-06-20T00:58:14.703" Title="Does the expression &quot;stall speed&quot; have a definition?" Tags="&lt;aerodynamics&gt;&lt;terminology&gt;&lt;stall&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27707" PostTypeId="1" AcceptedAnswerId="27708" CreationDate="2016-05-22T10:17:10.330" Score="3" ViewCount="232" Body="&lt;p&gt;How can a 777ER be operated from the Bologna runway which is only 9000ft? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recently took the Emirates flight and the aircraft was full. I suppose that it was close to max weight. According to wiki the required runway at max load is 10000ft so what is the trick behind this?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="1696" LastEditDate="2016-05-22T19:31:47.320" LastActivityDate="2016-05-22T19:31:47.320" Title="How can a 777ER fly from the 9000 ft runway at Bologna (LIPE)?" Tags="&lt;runways&gt;&lt;boeing-777&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27708" PostTypeId="2" ParentId="27707" CreationDate="2016-05-22T10:36:33.267" Score="7" Body="&lt;p&gt;LIPE - OMDB is only around 4,500 KM (2,800 NM) according to &lt;a href=&quot;http://www.gcmap.com/mapui?P=LIPE-OMDB&amp;amp;PM=b%3Adisc7&amp;amp;MS=wls&amp;amp;DU=mi&quot; rel=&quot;noreferrer&quot;&gt;Great Circle Mapper&lt;/a&gt;, which is nowhere close to the 773ER max range of 14,500 KM (7,830 NM), so one can make an educated guess that the aircraft wasn't at MTOW.&lt;/p&gt;&#xA;" OwnerUserId="3363" LastEditorUserId="595" LastEditDate="2016-05-22T12:18:37.950" LastActivityDate="2016-05-22T12:18:37.950" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27709" PostTypeId="2" ParentId="27706" CreationDate="2016-05-22T12:14:33.387" Score="9" Body="&lt;p&gt;Indeed, &quot;the stall speed of an airfoil doesn't exist.&quot; But the stall speed of an airplane does exist, though it's dependent on the aircraft weight $W$, load factor $n_z$, configuration (e.g., flaps position) and the air density. This variability makes it disadvantageous (for pilots---even dangerous) to think of an airplane's stall in terms of a definite stall speed $v_{Stall}$, as if it were a constant characteristic of the type. What &lt;em&gt;are&lt;/em&gt; (roughly) constant are the stall angle of attack and the stall lift coefficient $c_{L_{Stall}}$.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The equilibrium equation for the forces acting on the airplane &lt;em&gt;In stall&lt;/em&gt; in its symmetry plane and perpendicular to its velocity is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$n_z\cdot W = \frac{1}{2}\cdot\rho\cdot v^2_{Stall}\cdot S_{ref}\cdot c_{L_{Stall}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Doing the algebra, one can easily exspress the stall speed in terms of the remaining parameters ($\rho$ = density of air, $S_{ref}$ = reference area) The resulting expression will explain (i) that for an airplane, stall speed does exist; (ii) the nature of its dependences and (iii) that for an airfoil, to which force equilibrium does not apply, there is no &quot;stall speed.&quot;&lt;/p&gt;&#xA;" OwnerUserId="15036" LastEditorUserId="1961" LastEditDate="2016-05-25T06:12:12.697" LastActivityDate="2016-05-25T06:12:12.697" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27710" PostTypeId="2" ParentId="27689" CreationDate="2016-05-22T14:00:59.760" Score="40" Body="&lt;blockquote&gt;&#xA;&lt;p&gt;How is TACAN different from the VHF Omnidirectional Range (VOR) system?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;A very short question, but the answer calls for describing several techniques which are by themselves difficult to summarize without taking liberties with reality, so the post is rather long and should be read by sections of interest rather than totally at once. And for those not interested in the design techniques, fortunately there is a...&lt;/p&gt;&#xA;&lt;H3&gt;Short answer&lt;/H3&gt;&#xA;&lt;p&gt;Design principle:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Tactical_air_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;TACAN&lt;/a&gt; uses &lt;a href=&quot;https://en.wikipedia.org/wiki/Ultra_high_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;UHF&lt;/a&gt; to increase &lt;a href=&quot;https://en.wikipedia.org/wiki/Bearing_(navigation)&quot; rel=&quot;nofollow noreferrer&quot;&gt;bearing&lt;/a&gt; precision. It consists on a single integrated system performing bearing and distance determination at once. In this system, the ground station is a transponder and the interrogator is on-board the aircraft (contrary to the SSR transponder). Frequency is like graduations on a scale, when frequency increases the graduations on the scale are more dense, and readings are more accurate.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;VOR&lt;/a&gt; works on &lt;a href=&quot;https://en.wikipedia.org/wiki/Very_high_frequency&quot; rel=&quot;nofollow noreferrer&quot;&gt;VHF&lt;/a&gt; for bearing determination. No aircraft action is required to trigger the ground station signal which is permanent. To determine distance, another independent system, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Distance_measuring_equipment&quot; rel=&quot;nofollow noreferrer&quot;&gt;DME&lt;/a&gt;, is used. The DME has been borrowed to military and is actually a TACAN without its bearing components (so it is a transponder interrogated by the aircraft).&#xA;&lt;br&gt;&#xA;When selecting a VOR frequency in a civilian aircraft, the avionics actually sets the VOR receiver on this frequency, and the standalone DME &lt;em&gt;interrogator&lt;/em&gt; at some &amp;quot;paired&amp;quot; UHF frequency obtained from the ICAO standard pairing table (&lt;a href=&quot;https://www.casa.gov.au/sites/default/files/distance-measuring-equipment.pdf#page=6&quot; rel=&quot;nofollow noreferrer&quot;&gt;page 6&lt;/a&gt;). VOR and DME share nothing on board beyond the frequency pairing table.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Station antennas:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The original TACAN antenna is made of two small rotating drums with parasitic antenna elements (see details below). A TACAN can be installed on ships or mobile stations. The TACAN antenna is externally similar to a conventional VOR. A TACAN in Alaska during an exercise:&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/B5pN5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/B5pN5.jpg&quot; alt=&quot;TACAN mobile station in Alaska&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Radionavigation_mobile_station&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;br&gt;&#xA;The cylinder contains the rotating antenna system. In more modern TACAN, the mechanical rotation has been replaced by &lt;a href=&quot;https://en.wikipedia.org/wiki/Active_electronically_scanned_array&quot; rel=&quot;nofollow noreferrer&quot;&gt;electronically scanned arrays&lt;/a&gt;, reducing the size:&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/g4Vkv.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g4Vkv.jpg&quot; alt=&quot;Transportable TACAN&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;Transportable TACAN, &lt;a href=&quot;http://www.dbsant.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Doppler VOR (DVOR) are more common than conventional VOR (CVOR), because they can be located on airfields (CVOR: See below for details). The DVOR antenna is a large circular array with a central reference antenna and a large counterpoise under the array.  VOR are sometimes colocated with a DME station, in that case the DME vertical antenna is above and coaxial to the VOR system.&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/pgbCh.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pgbCh.jpg&quot; alt=&quot;Lambourne doppler VOR/DME&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;Lambourne VOR/DME, DME antenna on top of the central VOR reference antenna. (source: &lt;a href=&quot;https://en.wikipedia.org/wiki/VHF_omnidirectional_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;)&lt;/sup&gt;&#xA;&lt;br&gt;&#xA;Because the DME part is common to VOR/DME and TACAN, it is technically possible to associate a VOR to a TACAN to obtain a &lt;a href=&quot;https://i.stack.imgur.com/TpQp2.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;VORTAC&lt;/a&gt; station. Military use the TACAN, civilian use the VOR and the DME information of the TACAN:&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/rwjp6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/rwjp6.jpg&quot; alt=&quot;VORTAC station&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;A full TACAN in place of the previous DME antenna. &lt;a href=&quot;https://en.wikipedia.org/wiki/Tactical_air_navigation_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In addition VOR (CVOR/DVOR) uses &lt;a href=&quot;https://aviation.stackexchange.com/a/35269/3201&quot;&gt;Alford loop antennas&lt;/a&gt; which are &lt;a href=&quot;https://en.wikipedia.org/wiki/Antenna_(radio)#Polarization&quot; rel=&quot;nofollow noreferrer&quot;&gt;horizontally polarized&lt;/a&gt; and radiate low on the horizon. They are sensitive to reflection on obstacles. An &lt;a href=&quot;https://en.wikipedia.org/wiki/Counterpoise_(ground_system)&quot; rel=&quot;nofollow noreferrer&quot;&gt;electrical counterpoise&lt;/a&gt; is required to hide the ground and raise the radiation angle. This artificial ground plane can be very large:&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/6aUyV.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6aUyV.jpg&quot; alt=&quot;PFN Vortac&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;PFN Vortac (decommissioned), &lt;a href=&quot;http://catheyconstruction.com/project/pfn-doppler-vortac-relocation/&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Signals:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A VOR transmits bearing information continuously.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A TACAN only sends reply pulse pairs when interrogated (see the explanation below). These pairs encode both the bearing and DME information.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A TACAN is usually more powerful than a VOR and has a larger range of use.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;I'll focus on explaining bearing determination systems, and explain the DME as an integral component of the TACAN. In addition there are two types of VOR, conventional and Doppler, which work very differently even if they deliver compatible signals to the (unsuspecting) common receiver.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;H3&gt;Bearing determination principle&lt;/H3&gt;&#xA;&lt;p&gt;The common principle of bearing determination is to send two signals from the ground station:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;A &lt;em&gt;reference signal&lt;/em&gt; telling any receiver around the current orientation of the active signal.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A &lt;em&gt;variable signal&lt;/em&gt; allowing a particular receiver to determine when the active signal is &amp;quot;pointing&amp;quot; to the receiver (pointing is not the accurate word as the DVOR signals are omnidirectional, see more in &lt;a href=&quot;https://aviation.stackexchange.com/a/29900/3201&quot;&gt;this answer&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;The receiver determines its relative bearing by comparing these two signals. Both signals are sine functions, the orientation value is represented by the &lt;em&gt;current phase&lt;/em&gt; of this function. Both VOR and TACAN use this basic principle, albeit they realize it differently.&lt;/p&gt;&#xA;&lt;p&gt;The signal &lt;a href=&quot;https://en.wikipedia.org/wiki/Phase_(waves)&quot; rel=&quot;nofollow noreferrer&quot;&gt;phase&lt;/a&gt; has the major role in this story, so let's be sure we agree the meaning:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Any periodical (repetitive) signal can be seen as the result of a vector turning at some rate &lt;span class=&quot;math-container&quot;&gt;$\small \omega$&lt;/span&gt;. The sine function for angle &lt;span class=&quot;math-container&quot;&gt;$\small x$&lt;/span&gt; is &lt;span class=&quot;math-container&quot;&gt;$\small y = sin(x)$&lt;/span&gt;. Applied to a sinusoidal wave of frequency &lt;span class=&quot;math-container&quot;&gt;$\small f$&lt;/span&gt; and peak amplitude &lt;span class=&quot;math-container&quot;&gt;$\small A$&lt;/span&gt;, this becomes &lt;span class=&quot;math-container&quot;&gt;$\small y=A.sin(\omega t+\varphi)$&lt;/span&gt; where &lt;span class=&quot;math-container&quot;&gt;$\small \omega = 2 \pi f$&lt;/span&gt;. The angle &lt;span class=&quot;math-container&quot;&gt;$\small \omega t+\varphi$&lt;/span&gt;, has been split between the &lt;em&gt;phase&lt;/em&gt; &lt;span class=&quot;math-container&quot;&gt;$\small \omega t$&lt;/span&gt; and the &lt;em&gt;phase at origin&lt;/em&gt; &lt;span class=&quot;math-container&quot;&gt;$\small \varphi$&lt;/span&gt;. &lt;span class=&quot;math-container&quot;&gt;$\small \varphi$&lt;/span&gt; is null if we start a cycle at time 0, this is usually the case. More simply, the quantity &lt;span class=&quot;math-container&quot;&gt;$\small \omega t$&lt;/span&gt; represents how much the vector has turned at time &lt;span class=&quot;math-container&quot;&gt;$t$&lt;/span&gt;. It is an angle, reset after a full turn, therefore it indicates in the end which portion of a full cycle has already been spent (which &lt;em&gt;phase&lt;/em&gt; we are in the cycle). Visually:&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MwFhp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MwFhp.png&quot; alt=&quot;Phase angle of a sine wave&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Phase angle of a sine wave&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;From that, it is clear that comparing phases of two signals with the same frequency (simple to do with electronics) is equivalent to comparing how much time one lags behind the other (time is actually difficult to measure).&lt;/p&gt;&#xA;&lt;H3&gt;VOR types&lt;/H3&gt;&#xA;&lt;p&gt;Conventional VOR (CVOR) and Doppler VOR (DVOR) stations are perceived identically by the receiver, though they transmit very different signals. The DVOR use tricks to mimic a CVOR and deceive the CVOR receiver. CVOR have nearly disappeared from sight because, due to their sensitivity to reflections, they cannot be located on airfields or close to roads. However en-route/high altitude CVOR can be found at isolated places, the reason is they are more compact and have a smaller cone of silence than DVOR and reflections can be minimized, e.g. when the VOR is located at the top of a hill.&lt;/p&gt;&#xA;&lt;p&gt;Understanding the DVOR tricks without knowing how a CVOR works is difficult, and doesn't give clues on how the bearing is really determined. So I'm afraid we need to understand the CVOR before the DVOR.&lt;/p&gt;&#xA;&lt;H3&gt;Conventional VOR: CVOR&lt;/H3&gt;&#xA;&lt;p&gt;Early CVOR antenna used to be an array of four Alford loops at the corners of an imaginary square, known by their conventional names: NW, NE, SW and SE. NW+SE loops form the first pair, NE+SW loops form the second pair.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/udLWM.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/udLWM.png&quot; alt=&quot;CVOR with four Alford loops&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;CVOR with four Alford loops&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Alford loops are horizontally polarized and very sensitive to reflections on surrounding obstacles (&lt;a href=&quot;https://en.wikipedia.org/wiki/Multipath_propagation&quot; rel=&quot;nofollow noreferrer&quot;&gt;multipath&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;Recent generations of CVOR use a slotted antenna, which is a fixed cylinder with vertical slots (generally four slots):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hnAy7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hnAy7.png&quot; alt=&quot;CVOR with slotted antenna&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;CVOR with slotted antenna and the DME antenna on top. Source: &lt;a href=&quot;https://aviatecho.com/le-vor/&quot; rel=&quot;nofollow noreferrer&quot;&gt;AviaTecho&lt;/a&gt;.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;A counterpoise is placed under the array to hide the VOR shelter and the ground and raise the radiation direction, it has the dual effect of minimizing undesirable reflection on the shelter and the ground and reducing the &lt;a href=&quot;https://aviation.stackexchange.com/q/35255/3201&quot;&gt;cone of silence&lt;/a&gt; above the VOR.&lt;/p&gt;&#xA;&lt;p&gt;CVOR creates and uses reference and variable signals this way:&lt;/p&gt;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;A low frequency generator creates three 30 Hz signals, identical except their phases. Two audio signals are derived from a &lt;em&gt;reference&lt;/em&gt; signal: The &lt;em&gt;sin&lt;/em&gt; signal has a phase at origin of -90° and the &lt;em&gt;cos&lt;/em&gt; signal has a phase at origin of +90° (the point is sin and cos signals are in phase opposition).&#xA;&lt;br&gt;&#xA;The phase of the reference conceptually represents a direction and is often called the &lt;em&gt;goniometer&lt;/em&gt;. As this signal frequency is 30 Hz, the imaginary direction it represents sweeps 360° 30 times per second (1,800 rpm, this is pure abstraction, there is no rotating parts in a CVOR).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A low frequency generator creates a 9960 Hz signal which is FM modulated by the reference. This signal is known as the &lt;em&gt;reference &lt;a href=&quot;https://en.wikipedia.org/wiki/Subcarrier&quot; rel=&quot;nofollow noreferrer&quot;&gt;subcarrier&lt;/a&gt;&lt;/em&gt;.&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/oCHc5.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oCHc5.png&quot; alt=&quot;Conventional VOR block diagram&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;Conventional VOR block diagram&lt;/sup&gt;&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A HF generator creates a &lt;a href=&quot;https://en.wikipedia.org/wiki/Carrier_wave&quot; rel=&quot;nofollow noreferrer&quot;&gt;carrier&lt;/a&gt; of frequency f (f being the VOR frequency), this carrier is split in three parts:&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;one part is AM modulated by the &lt;em&gt;reference subcarrier&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;another is AM modulated by &lt;em&gt;sin&lt;/em&gt;.&lt;/li&gt;&#xA;&lt;li&gt;the last part is AM modulated by &lt;em&gt;cos&lt;/em&gt;.&lt;br /&gt;&#xA;&lt;br&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The HF signal with the reference subcarrier is sent to all antennas. This way the reference can be received identically regardless of the position of the receiver around the CVOR.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The two other HF signals have first their carrier removed, so that only the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sideband&quot; rel=&quot;nofollow noreferrer&quot;&gt;sidebands&lt;/a&gt; subsist. This is to prevent carriers to interfere in space, &lt;a href=&quot;https://en.wikipedia.org/wiki/Wave_interference&quot; rel=&quot;nofollow noreferrer&quot;&gt;interferences&lt;/a&gt; must occur only between sidebands.&#xA;&lt;br&gt;&#xA;Then one signal is sent to the NW+SE pair of antennas, the other signal is sent to the other pair (remember the two pairs are perpendicular).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Space_modulation&quot; rel=&quot;nofollow noreferrer&quot;&gt;space modulation&lt;/a&gt; magic does the rest. The &lt;em&gt;sin&lt;/em&gt; and &lt;em&gt;cos&lt;/em&gt; sidebands are added as field vector values, sometimes the individual amplitudes are added, sometimes they are subtracted, in variable proportion. This results in an unbalanced &lt;a href=&quot;https://en.wikipedia.org/wiki/Cardioid&quot; rel=&quot;nofollow noreferrer&quot;&gt;cardioid&lt;/a&gt; pattern (more precisely a &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Lima%C3%A7on&quot; rel=&quot;nofollow noreferrer&quot;&gt;Limaçon de Pascal&lt;/a&gt;&lt;/em&gt;) which rotates around the VOR antennas at 1,800 rpm, the direction being linked to the phase of the &lt;em&gt;reference&lt;/em&gt; (or &lt;em&gt;sin&lt;/em&gt; or &lt;em&gt;cos&lt;/em&gt;, as they are all linked by fixed values).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The signal resulting from space modulation appears like being a carrier AM modulated according to the direction of the virtual &amp;quot;rotating antenna&amp;quot;. The AM modulation is also a 30 Hz signal, and is known as the &lt;em&gt;variable signal&lt;/em&gt;.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The resulting signal also contains the unmodified (and constant amplitude) carrier with its reference subcarrier.&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/aUwE7.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aUwE7.png&quot; alt=&quot;CVOR spectrum&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;br&gt;&#xA;&lt;sup&gt;CVOR spectrum&lt;/sup&gt;&#xA;&lt;br&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;To determine the bearing (the radial) of the receiver relative to the CVOR, one only needs to compare the phase of the variable signal with the phase of the reference signal. Both are contained in the resulting signal. The phase of the reference signal and the phase of the variable signal are equal when the reference &amp;quot;points&amp;quot; to north (per principle at this time both phases have a value of 135°, the sum of 45° and 90°, but the actual value has no influence, only the phase difference is meaningful):&#xA;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Bbi4b.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Bbi4b.png&quot; alt=&quot;VOR: Determination of the bearing by comparing phases&quot; /&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;br&gt;&#xA;&lt;sup&gt;VOR: Determination of the bearing by comparing phases&lt;/sup&gt;&#xA;&lt;br&gt;&#xA;Now we know the principle of the CVOR, it more easy to understand the principle of the DVOR. The DVOR was created to make up for some weaknesses in the CVOR: The CVOR is not terribly accurate unless the installation site is very carefully selected (no obstacle). That means isolated points, not airfields. That's not the preferred option for maintenance and this often precludes having the CVOR aligned with the runway for a VOR approach.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;H3&gt;From CVOR to Doppler VOR, ensuring retro-compatibility&lt;/H3&gt;&#xA;&lt;p&gt;The lack of precision of the VOR is rooted in two design choices:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The antennas are close to each other, any default in their placement has great consequences in the accuracy.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The variable signal is AM modulated, AM modulation is deadly subject to errors created by electromagnetic noise and multipath.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In the Doppler VOR (once again... there are two types of DVOR, the single sideband and the double sideband, I'll describe the DSB here):&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The two active antennas are at a large distance from each other (diametrically opposed).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The variable signal is FM modulated.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;In order to be compatible with the CVOR receiver, other changes had to be made:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;As the receiver still compares two signals, one being AM, the other FM, the reference signal must be AM modulated.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Because the result of the phase comparison is now inverted (variable minus reference becomes reference minus variable), the direction of rotation of the pattern must also be inverted (anti-clockwise instead of clockwise).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Because the pair of antennas used for the variable signal creates deliberately a Doppler effect, the reference must be sent on a specific central antenna preserved from the Doppler effect.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;H3&gt;Doppler VOR: DVOR&lt;/H3&gt;&#xA;&lt;p&gt;The principle of a Doppler VOR is to create the frequency modulation by &lt;a href=&quot;https://en.wikipedia.org/wiki/Doppler_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;Doppler effect&lt;/a&gt; rather than by electronic modulation. The Doppler effect occurs with a moving wave source: In spite the source has a constant frequency, when it comes closer to the receiver the apparent frequency is higher than the actual frequency. How much higher depends only on the closure rate.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7TG6e.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7TG6e.png&quot; alt=&quot;Doppler effect on train noise&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Doppler effect on train noise: Sound is higher-pitched at the front than at the rear&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;In the DVOR, pairs of opposed antennas (still Alford loops) are constantly switched on/off, scanning the full array anti-clockwise, the full scan being done 30 times per second. Actually there are two &lt;em&gt;groups&lt;/em&gt; of antennas rather than two antennas involved to allow for &lt;em&gt;blending&lt;/em&gt; (smooth transition from one pair to the next), but let's simplify for a second. From a receiver standpoint, the signal seems to come from a moving source, and therefore a Doppler shift will occur in a proportion which depends on the apparent direction of the move.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hjKhj.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hjKhj.png&quot; alt=&quot;DVOR Doppler effect&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;DVOR Doppler effect&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;To allow for compatibility with the CVOR receiver, this shift must be at most 480 Hz, 480 Hz being the FM swing of the subcarrier in the CVOR. A simple calculation shows the array diameter must be about 14 m (46 feet).&lt;/p&gt;&#xA;&lt;p&gt;To generate the FM modulated signal, the unmodulated 9960 Hz subcarrier is sent on the &amp;quot;rotating&amp;quot; pair of antennas. The Doppler shift is maximum when the receiver direction is tangential to the pair trajectory and minimal when the pair is perpendicular to the direction of the receiver. This shift is exactly representative of the aircraft bearing and is the variable signal modulation we need.&lt;/p&gt;&#xA;&lt;p&gt;From a radio signal perspective, only the sideband frequencies are used to transmit the 9960 Hz subcarrier (VOR frequency f +/- 9960 Hz). The carrier is itself sent on the central antenna, AM modulated by the reference signal. This way the carrier is not subject to the Doppler shift.&lt;/p&gt;&#xA;&lt;p&gt;Bottom line... Like in the CVOR, the receiver sees the composite signal: A carrier AM modulated with a 30 Hz (which is the reference instead of the variable signal), with a subcarrier FM &amp;quot;modulated&amp;quot; as the result of the Doppler effect, at 30 Hz (the frequency of the scan, it now represents the variable signal instead of the reference) and with a swing not far from the expected 480 Hz.&lt;/p&gt;&#xA;&lt;p&gt;Blending: If a pair of antennas were used one at a time, the number of measurable bearings would be equal to the number of antennas in the array (about 50). To create a more continuous scan (and therefore a larger number of measurable bearings), the antennas which precede and follow the main antenna are also fed by the subcarrier signal, but with a smaller power. This &amp;quot;blends&amp;quot; the transition from a scan position to the next one.&lt;/p&gt;&#xA;&lt;p&gt;See also &lt;a href=&quot;https://aviation.stackexchange.com/q/33834/3201&quot;&gt;What causes the phase to change in a VOR?&lt;/a&gt; for a better explanation of the DVOR.&lt;/p&gt;&#xA;&lt;H3&gt;TACAN bearing&lt;/H3&gt;&#xA;&lt;p&gt;A TACAN is based on a stationary antenna plus a rotating parasitic system. The base antenna is vertical and common to the distance and bearing measurement instruments.&lt;/p&gt;&#xA;&lt;p&gt;Parasitic elements in the aerial field refer to passive antenna elements added to the actual active radiator. A reflector decreases the gain on its side, a director increases the gain on its side (&lt;a href=&quot;https://en.wikipedia.org/wiki/Directional_antenna&quot; rel=&quot;nofollow noreferrer&quot;&gt;more&lt;/a&gt;). The well-known Yagi directional antenna (here in an horizontal polarization) has the two types of parasitic elements:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/TpQp2.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/TpQp2.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.hamradio.me/antennas/loop-fed-array-lfa-planar-yagi-uda.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;, modified)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;These elements are used in the TACAN, but they are rotating around the active element:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/P2KzB.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/P2KzB.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;BR&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;(&lt;a href=&quot;http://www.opticfox.com/2a4x2/tacan-fun.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;, modified)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The central element, which is the one also used for the DME portion, transmits a constant amplitude signal.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;A rotating drum with a reflector electrically adjusts the radiation pattern, adding a signal dip (low gain) that rotates at 900 RPM, which is equivalent to a 15 Hz amplitude modulation. The radiation pattern in the horizontal plan takes the shape of a cardioid:&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/eMMRK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eMMRK.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;BR&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://books.google.fr/books?id=tsMdMQsLF48C&amp;amp;pg=PP1&amp;amp;lpg=PP1&amp;amp;dq=Advances%20in%20Electronics%20and%20Electron%20Physics,%20Volume%2068&amp;amp;source=bl&amp;amp;ots=jEApKDsvUY&amp;amp;sig=1vrL82bfvt0irUvpa6MN33gy-ps&amp;amp;hl=fr&amp;amp;sa=X&amp;amp;ved=0ahUKEwjgwoKSnvHMAhUHsxQKHbBnCgoQ6AEIODAD&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advances in Electronics and Electron Physics, Volume 68&lt;/a&gt;, modified)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Another drum with a set of 9 directors, mechanically linked to the first one, creates a 135 Hz (9x15) additional amplitude ripple over the 15 Hz modulation:&lt;BR&gt;&lt;BR&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/7Ogjk.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7Ogjk.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;BR&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://books.google.fr/books?id=tsMdMQsLF48C&amp;amp;pg=PP1&amp;amp;lpg=PP1&amp;amp;dq=Advances%20in%20Electronics%20and%20Electron%20Physics,%20Volume%2068&amp;amp;source=bl&amp;amp;ots=jEApKDsvUY&amp;amp;sig=1vrL82bfvt0irUvpa6MN33gy-ps&amp;amp;hl=fr&amp;amp;sa=X&amp;amp;ved=0ahUKEwjgwoKSnvHMAhUHsxQKHbBnCgoQ6AEIODAD&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advances in Electronics and Electron Physics, Volume 68&lt;/a&gt;, modified)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Now we need to start again the reasoning taking into account that the TACAN signal isn't transmitted permanently, but only keyed (switched on/off) by bursts of information. Burst are of two kinds:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Reference bursts&lt;/li&gt;&#xA;&lt;li&gt;DME responses.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;Reference bursts are generated according to the orientation of the modulation pattern:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When the 15 Hz peak faces North a main reference burst is sent. The burst consists of 24 pulses&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;with an asymmetric duty cycle.&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;When any of the 135 Hz peaks faces East, an auxiliary reference burst is sent. The burst consists of 24 pulses with a symmetric duty cycle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/UNmjn.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/UNmjn.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;BR&gt;&#xA;&lt;sup&gt;(Source: &lt;a href=&quot;https://books.google.fr/books?id=tsMdMQsLF48C&amp;amp;pg=PP1&amp;amp;lpg=PP1&amp;amp;dq=Advances%20in%20Electronics%20and%20Electron%20Physics,%20Volume%2068&amp;amp;source=bl&amp;amp;ots=jEApKDsvUY&amp;amp;sig=1vrL82bfvt0irUvpa6MN33gy-ps&amp;amp;hl=fr&amp;amp;sa=X&amp;amp;ved=0ahUKEwjgwoKSnvHMAhUHsxQKHbBnCgoQ6AEIODAD&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advances in Electronics and Electron Physics, Volume 68&lt;/a&gt;. Modified)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The duration of these bursts is only a portion of the 15 Hz cycle, meaning that if there is few aircraft DME interrogations, most of the time the TACAN signal is not keyed, therefore not transmitted. This lack of transmission would create a difficulty for the aircraft receiver:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;To adjust its receiver gain (AGC) to counter fading.&lt;/li&gt;&#xA;&lt;li&gt;To identify the 15 Hz and 135 Hz modulations.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;To maintain the capability of reception, the TACAN signal is instead keyed at a constant rate of 2,700 pairs of pulses per second, adding &lt;em&gt;squitter pulses&lt;/em&gt; if necessary to fill the blanks. The more the DME interrogations are received by the TACAN, the more DME reply bursts are sent, the less squitter pulses are necessary (more in &lt;a href=&quot;http://everyspec.com/MIL-STD/MIL-STD-0100-0299/download.php?spec=MIL-STD-291C.011561.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;MIL-STD-291&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Zw5jE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Zw5jE.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;BR&gt;&#xA;&lt;sup&gt;The 135 Hz signal has been removed for simplification (&lt;a href=&quot;http://pages.erau.edu/%7Eericksol/projects/shuttle/21ExternalNavigationSystemsGPSTACANMSBLSPonso.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The 135 Hz modulation is used for the bearing determination. By comparing the time between an auxiliary burst and the subsequent reception of one of the 9 signal peaks, it is possible to determine the aircraft bearing relative to the ground station. The main burst (15 Hz) is used to disambiguate which of the 9 lobes was used, and therefore which of the 40° (360/9) sector is actually relevant for the bearing.&lt;/p&gt;&#xA;&lt;p&gt;In theory the use of the top end of the UHF band and the 135 Hz ripple increase the bearing accuracy by one order of magnitude compared to the VOR. In practical this is less, but still better than the VOR.&lt;/p&gt;&#xA;&lt;p&gt;The &lt;a href=&quot;https://i.stack.imgur.com/MwFhp.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;DME&lt;/a&gt; principle is to measure the time a radio signal takes for a roundtrip to the ground station. As radio waves travel at light speed, knowing the time is knowing the distance. &amp;quot;&lt;em&gt;The aircraft interrogates the ground transponder with a series of pulse-pairs (interrogations) and, after a precise time delay (typically 50 microseconds), the ground station replies with an identical sequence of pulse-pairs.&lt;/em&gt;&amp;quot; (Wikipedia).&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-10-28T19:39:11.540" LastActivityDate="2020-10-28T19:39:11.540" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="27711" PostTypeId="2" ParentId="27706" CreationDate="2016-05-22T15:47:14.293" Score="3" Body="&lt;p&gt;A stall speed can be predicted if the other variables that are factors for a stall at any given speed are known.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Obviously, the point of discussion with stall speed is to make sure everyone has awareness that it isn't a fixed number, and it is definitely not the authoritative variable regarding the point at which an airfoil will stall; that would be the angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason we need to acknowledge the existence of an estimated stall speed during common, predictable flight conditions is because the airspeed is going to be one of the pilot's primary focus points during critical phases of flight where a stall presents a greater risk.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Attempting to utilize a speed is just more practical.  There are virtually unlimited stall speeds, so in the same way we refer to a number divided by zero as &quot;undefined,&quot; stall speed is also numerically undefined. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Yes, it has a literary definition, but no, it doesn't have a numerical definition, just a reference point for various operational configurations in different aircraft.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-05-22T15:47:14.293" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27712" PostTypeId="2" ParentId="27706" CreationDate="2016-05-22T15:58:59.923" Score="6" Body="&lt;p&gt;There is not a single stall speed, because stall depends on&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/21035/does-stall-angle-of-attack-in-inverted-flight-change-due-to-the-camber-of-an-asy/21041?s=1%7C0.5402#21041&quot;&gt;Angle of Attack&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/2903/how-does-stall-depend-on-angle-of-attack-but-not-speed/3620#3620&quot;&gt;Pitch rate&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/6366/what-is-the-immediate-cause-of-stall/6375#6375&quot;&gt;Mach number&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;Reynolds number&lt;/li&gt;&#xA;&lt;li&gt;Load factor&lt;/li&gt;&#xA;&lt;li&gt;Flap settings&lt;/li&gt;&#xA;&lt;li&gt;Center of gravity position.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, for regulations the simplification of a single stall speed is helpful; here it is the minimum speed at which the aircraft can be controlled with idle power. Note that the definition for stall speed in the US regulations for GA aircraft (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=22c37e4b8c1577347f37ac1944ae5941&amp;amp;mc=true&amp;amp;node=se14.1.23_149&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Part23 subpart B §23.49&lt;/a&gt;) is quite vague, allowing for details like the flight mass and altitude being&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;in the condition existing in the test, in which V$_{SO}$ and V$_{S1}$ are&#xA;  being used;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;At least the center of gravity needs to be in the position which results in the highest stall speed (normally most forward). The controllability condition can result in the stall speed not being at the highest lift coefficient, but at the elevator control limit. Note also that it is not determined in level flight, but with engines idle or providing no thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Your linked example is rather theoretical - the lift curve slope of an airplane rarely looks so nice and clean like in the example. If you test a wing with a constant cross section in the wind tunnel, the resulting lift curve slope allows to define a maximum lift coefficient, and with this you can calculate a theoretical stall speed when adding wing loading and absolute size (for the Reynolds number). But the stall speed as measured in flight test will be different and most likely higher.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2016-05-22T15:58:59.923" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27713" PostTypeId="2" ParentId="27706" CreationDate="2016-05-22T16:04:06.317" Score="4" Body="&lt;p&gt;'Stall speed' is defined only with respect to the aircraft as it is the case where it has a physical meaning. We define stall as the point where the airfoil or wing stops producing the necessary lift due to flow separation (This is an extremely simple definition, which will suffice for now), i.e where the lift coefficient is maximum.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For aircraft, the stall speed is given as where the wing reaches the max. lift coefficient. Basically, we are using the stall speed because it is directly available to the pilot i.e. it is a derived quantity, based on the angle of attack, configuration etc. among others. On by itself, the value has no meaning, as you pointed it out yourself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, coming to the airfoil, the same (or similar) definition cannot be used as there is no way of saying lift equals weight due to the nature of airfoil itself. Thus, the stall speed is a performance term, not an aerodynamic one.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="22726" LastEditDate="2019-06-20T00:58:14.703" LastActivityDate="2019-06-20T00:58:14.703" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27717" PostTypeId="1" CreationDate="2016-05-22T20:14:33.593" Score="6" ViewCount="314" Body="&lt;p&gt;In a commercial airliner at FL370, in the event of rapid (explosive) decompression, will the cabin air fog? And can that fog trip smoke detectors?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pressurized aircraft can have a cabin altitude of 6,000 ft, or so. What is the differential pressure at 37,000 ft? Again, would an explosive decompression of 8-9 PSI, fog the interior environment?&lt;/p&gt;&#xA;" OwnerUserId="15067" LastEditorUserId="1467" LastEditDate="2016-05-22T20:56:59.050" LastActivityDate="2016-05-26T08:13:01.093" Title="Could an explosive decompression trigger the smoke detectors?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;&lt;airliner&gt;" AnswerCount="1" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27718" PostTypeId="1" AcceptedAnswerId="27720" CreationDate="2016-05-22T23:38:09.007" Score="4" ViewCount="836" Body="&lt;p&gt;Somehow, a variation of &lt;a href=&quot;https://aviation.stackexchange.com/questions/13422/how-do-long-haul-pilots-cope-with-boredom&quot;&gt;How do long-haul pilots cope with boredom?&lt;/a&gt; . &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Has it ever happened that the pilots started some small talk about politics, or football, or favourite rock band, or that one cheated with the other's SO, and the discussion degenerated in some strong arguments, if not a fight? Is there anything in place to prevent that (like, procedures on what you're supposed to talk about during free moments)?&lt;/p&gt;&#xA;" OwnerUserId="15066" LastEditorUserId="12220" LastEditDate="2016-05-23T01:10:38.040" LastActivityDate="2016-05-23T14:53:58.627" Title="Has a &quot;fight&quot; ever happened in the cockpit?" Tags="&lt;airline-pilot&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27719" PostTypeId="1" CreationDate="2016-05-23T01:25:39.127" Score="14" ViewCount="1540" Body="&lt;p&gt;There are many kinds of jets on an aircraft carrier. I'm curious how they're moved around below deck. They have to be moved around for storage and to get to and from the large elevator that takes them up to and down from the flight deck.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how are they moved? Is there some tug? Or something powering their wheels? I really hope they don't have to use their jet engines below deck, as that seems very dangerous to me.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-05-23T02:55:38.197" LastActivityDate="2019-03-17T07:09:39.273" Title="How are naval jets moved around below the deck of a carrier?" Tags="&lt;military&gt;&lt;jet&gt;&lt;aircraft-carrier&gt;&lt;aircraft-storing&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27720" PostTypeId="2" ParentId="27718" CreationDate="2016-05-23T01:54:46.770" Score="4" Body="&lt;p&gt;I've never seen anything about pilots fighting &lt;em&gt;during&lt;/em&gt; the flight but on &lt;a href=&quot;http://timesofindia.indiatimes.com/india/Air-India-co-pilot-beats-up-captain-inside-cockpit/articleshow/46818054.cms&quot; rel=&quot;nofollow&quot;&gt;Air India 611&lt;/a&gt; they fought &lt;em&gt;before&lt;/em&gt; the flight then proceeded to fly anyway. There are differing accounts of whether it was physical or just verbal. The captain claims he was punched for calling his older copilot &quot;uncle.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On &lt;a href=&quot;http://viewfromthewing.boardingarea.com/2015/09/21/what-actually-happened-on-that-united-express-flight-where-the-fight-broke-out-between-pilot-and-co-pilot/&quot; rel=&quot;nofollow&quot;&gt;Express Jet 4453&lt;/a&gt; apparently they got into such a heated argument that when they landed, the flight attendant made the passengers disembark. They continued on in a different plane with a different flight crew.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are reports of a fight between pilots on a &lt;a href=&quot;https://usattravel.wordpress.com/2015/09/01/pilot-on-pilot-fight-breaks-out-in-cockpit-during-flight/&quot; rel=&quot;nofollow&quot;&gt;China United Airlines&lt;/a&gt; flight but finding out what actually happened will be difficult.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On &lt;a href=&quot;http://www.dailymail.co.uk/news/article-2121240/JetBlue-pilot-Clayton-Osbon-restrained-PASSENGERS-going-berserk-mid-flight.html&quot; rel=&quot;nofollow&quot;&gt;JetBlue flight 191&lt;/a&gt; the captain started ranting and raving to the point where flight attendants and passengers had to remove him and physically restrain him for the duration of the flight. There's &lt;a href=&quot;https://youtu.be/6OluuEH16MY&quot; rel=&quot;nofollow&quot;&gt;video&lt;/a&gt; of the incident. He was charged with interfering with a flight crew but was found not guilty by reason of insanity. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And on &lt;a href=&quot;https://www.washingtonpost.com/news/morning-mix/wp/2016/01/31/delta-flight-grounded-after-crew-members-get-into-fight-with-flying-fists/&quot; rel=&quot;nofollow&quot;&gt;Delta 2598&lt;/a&gt; the pilots did an emergency landing when two flight attendants got into a brawl.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-05-23T04:57:09.357" LastActivityDate="2016-05-23T04:57:09.357" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27721" PostTypeId="1" AcceptedAnswerId="27723" CreationDate="2016-05-23T02:16:37.240" Score="27" ViewCount="6424" Body="&lt;p&gt;I keep seeing these land based vehicles whenever I am looking airports on flightradar24, like in the image below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QRI6h.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QRI6h.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why do they come up on the radar? Do they have a transponder? What is the purpose of these vehicles?&lt;/p&gt;&#xA;" OwnerUserId="1534" LastActivityDate="2016-06-24T12:40:47.830" Title="What are these vehicles with no callsign used for?" Tags="&lt;airport&gt;&lt;ads-b&gt;&lt;flightradar24&gt;" AnswerCount="2" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27722" PostTypeId="2" ParentId="27721" CreationDate="2016-05-23T03:39:40.913" Score="8" Body="&lt;p&gt;On &lt;a href=&quot;https://aviation.stackexchange.com/q/19087/8730&quot;&gt;this question&lt;/a&gt; it is mentioned that ground support vehicles are equipped with ground transponders that work with the airport ground radar. I doubt they have ADS-B. They are most likely getting a feed from the ground radar system. In &lt;a href=&quot;http://forum.flightradar24.com/threads/7257-Ground-vehicles&quot; rel=&quot;nofollow noreferrer&quot;&gt;this thread&lt;/a&gt; on the Flightradar24 forum they discuss what types of ground systems are compatible with the FR24 recievers. One of them mentions that the feed can apparently be switched off by the controllers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can toggle ground vehicles on and off in settings,&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-05-23T04:02:02.223" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27723" PostTypeId="2" ParentId="27721" CreationDate="2016-05-23T05:28:25.743" Score="33" Body="&lt;p&gt;They have Mode-S transponders / ADS-B transmitters specifically for vehicles such a the &lt;a href=&quot;http://www.era.cz/air-traffic-management/squid&quot; rel=&quot;nofollow&quot;&gt;ERA SQUID&lt;/a&gt;, &lt;a href=&quot;https://www.thalesgroup.com/en/mosquito-airfield-vehicle-transponder&quot; rel=&quot;nofollow&quot;&gt;Thales MOSQUITO&lt;/a&gt; or &lt;a href=&quot;http://saab.com/globalassets/commercial/security/air-traffic-management-and-airport-security/air-traffic-management-solutions/veelo/veelo-nextgen_downloads_brochure.pdf&quot; rel=&quot;nofollow&quot;&gt;Saab Sensis VeeLo&lt;/a&gt;&lt;sup&gt;PDF&lt;/sup&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically vehicles that operate on taxiways and runways are equipped with such transponders, which ensures the vehicles can be tracked by the Advanced Surface Movement Guidance and Control System (A-SMGCS).&#xA;Vehicles that only operate near parked aircraft are usually not equipped.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When using a magnetic mount, these transponders can be easily transferred between cars. This reduces the total number of transponders needed, but makes it necessary to reprogram the call sign after each transfer. For this reason it may have been decided to have no call sign in the transponder at all for these vehicles at Sydney airport.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of an airport using fixed installations with call signs is &lt;a href=&quot;https://www.flightradar24.com/52.32,4.75/13&quot; rel=&quot;nofollow&quot;&gt;Amsterdam airport&lt;/a&gt;. Using FR24 you can see bird control, maintenance, supervisors, tugs, fire trucks etc. driving at the airport and sometimes,  when they forget to turn the system off, on the highway.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;After some further investigation, I am fairly sure they use the Saab Sensis VeeLo in Sydney. The units are magnetically mounted to the vehicles. Each unit transmits using a fixed unique 24-bit address (like all Mode-S transponders /  ADS-B tranmitters) and no call sign. In the A-SMGCS software the 24-bit address is mapped to a call sign which is displayed on the Controller Working Position. There is procedure in place to ensure that when a vehicle is entering the manoeuvring area the correct mapping between the 24 bit address and the call sign is in the A-SMGCS system. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2016-06-24T12:40:47.830" LastActivityDate="2016-06-24T12:40:47.830" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27724" PostTypeId="1" CreationDate="2016-05-23T06:00:21.913" Score="10" ViewCount="2242" Body="&lt;p&gt;This past Saturday I was taking off from runway 22 at Catalina Airport (IATA: AVX) when I heard on radio a GA pilot requesting the tower to turn off VASI after requesting weather advisory.  I did not know if that airplane was on ground or in air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the clouds were gathering over and I am not an IFR pilot, I was concentrating on the fast moving clouds. After a while he asked for VASI to be turned back on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I wonder why did that GA pilot ask to turn off VASI and get them turned on shortly afterwards?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a side note, I got lucky and saw the giant Shuttle fuel tank being towed down below near LA Forum to LA Science museum; took some pictures!&lt;/p&gt;&#xA;" OwnerUserId="9265" LastEditorUserId="65" LastEditDate="2016-07-30T22:32:31.733" LastActivityDate="2016-07-30T22:32:31.733" Title="Why would a pilot ask the tower to turn the VASI off?" Tags="&lt;single-engine&gt;&lt;airport-lighting&gt;&lt;vasi&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27725" PostTypeId="2" ParentId="27724" CreationDate="2016-05-23T06:20:22.403" Score="22" Body="&lt;p&gt;It could have been a flight instructor with a student that was becoming too reliant on the VASI's slope information for visual approaches to landing, and he wanted to force the student to do without.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-05-23T06:20:22.403" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27726" PostTypeId="1" AcceptedAnswerId="27727" CreationDate="2016-05-23T08:12:10.573" Score="15" ViewCount="4550" Body="&lt;p&gt;I've read several times that the navy versions of jet aircraft need to have a strengthened undercarriage. Here is &lt;a href=&quot;https://en.wikipedia.org/wiki/Navalised_aircraft&quot; rel=&quot;nofollow noreferrer&quot;&gt;one example&lt;/a&gt;, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan_MiG-29K&quot; rel=&quot;nofollow noreferrer&quot;&gt;another&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've always just automatically assumed this was needed because aircraft landings are &quot;rough&quot;. That is, the aircraft smacks down hard on the carrier deck (or so went my assumption).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now I find myself questioning this. Naval jets land by catching a wire that brakes them hard. They may also takeoff with a catapult, which is some running device that pulls the nose gear forward at high g's.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what is the real reason that naval versions of jets need a strengthened undercarriage?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2017-08-14T11:01:35.307" LastActivityDate="2017-08-14T11:01:35.307" Title="Why do naval jet aircraft need to have strengthened undercarriages?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;fighter&gt;&lt;aircraft-carrier&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27727" PostTypeId="2" ParentId="27726" CreationDate="2016-05-23T08:48:58.377" Score="37" Body="&lt;p&gt;The landing on carrier is indeed hard. The reason is not the deceleration (which is handled by the hook), but the touch-down. Since the deck is short, the wires can't be spaced very far apart, so the aircraft must touch down very precisely. Since the precision is better at steeper angle, the aircraft landing on carrier &lt;em&gt;do not flare.&lt;/em&gt; At all. So they hit the deck at more than twice the vertical speed compared to typical landing on decent runway.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-05-23T08:48:58.377" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27728" PostTypeId="1" AcceptedAnswerId="27735" CreationDate="2016-05-23T09:52:10.463" Score="13" ViewCount="1216" Body="&lt;p&gt;This question is bordering between aviation and biology. I am posting it here, since it is really about aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At first, one would think, that birds should be aerodynamically stable to save themselves the effort of maintaining stable flight.&#xA;However, even if humans had rigid joints they are in an unstable configuration other than four-legged animals. Thus, stability does not seem to be a must for biology, at least in certain aspects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, are birds aerodynamically stable? Are all of them, or are some species which are and some which aren't?&lt;/p&gt;&#xA;" OwnerUserId="9892" LastActivityDate="2016-05-28T07:41:01.630" Title="Are birds aerodynamically stable?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;" AnswerCount="1" CommentCount="11" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27730" PostTypeId="2" ParentId="27717" CreationDate="2016-05-23T12:29:56.513" Score="5" Body="&lt;p&gt;In an explosive decompression the cabin air may fog, this is because of rapid cooling causing the moisture in the air to condense. How thick it is and how long it may last depends on a number of factors. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are two types of smoke detectors, these are optical particle detection devices and ionization devices. Both types are used on commercial aircraft, some detectors have both methods built in.  Ionization devices are tripped by changes in the electrical conductivity of the air flowing through them and are not very sensitive to steam. Optical smoke detectors work on a different principle, detecting light being scattered by particles in the air. Optical devices are susceptible to false readings from moisture, in fact manufacturers of home devices recommend they are installed away from bathrooms to avoid false alarms. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, airplane certified units are designed and built to a very high standard, the FAA states in the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/amt_airframe_handbook/media/ama_Ch17.pdf&quot; rel=&quot;nofollow&quot;&gt;Aviation Maintenance Handbook&lt;/a&gt; that requirements for fire protection systems include:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;No false warnings under any flight or ground condition.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So it is very likely that the manufacturers have taken steam into account, after all cabins sometimes fill with steam when the air conditioning has been turned on when if the air is very moist. An extreme example is &lt;a href=&quot;http://www.dailymail.co.uk/news/peoplesdaily/article-3099148/Shenzhen-Airlines-plane-cabin-fills-steam-high-humidity.html&quot; rel=&quot;nofollow&quot;&gt;this flight at Shenzen&lt;/a&gt;. That did not set off smoke alarms, and although I've never seen it that bad I have personally been in the cabin when it's noticeably filled with steam and there were no smoke alarms. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, the cabin can fill with steam in an explosive decompression, but it is unlikely - but possible - that the smoke alarms would go off. &lt;/p&gt;&#xA;" OwnerUserId="1791" LastEditorUserId="1791" LastEditDate="2016-05-26T08:13:01.093" LastActivityDate="2016-05-26T08:13:01.093" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27731" PostTypeId="2" ParentId="27719" CreationDate="2016-05-23T12:35:03.293" Score="9" Body="&lt;p&gt;As Simon pointed out, they use tugs. Obviously the engines are not started below the deck as it would have potentially deadly consequences. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tugs are either electric or powered by a diesel/JP-5 engine. For example, the USN uses the &lt;a href=&quot;http://navyaviation.tpub.com/14014/css/A-S32A-32-Aircraft-Towing-Tractor-217.htm&quot; rel=&quot;noreferrer&quot;&gt;A/S32A-32 towing tractor&lt;/a&gt; (also called spotting dolly SD-2), among others.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zyDLs.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zyDLs.jpg&quot; alt=&quot;A/S32A&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://zone-five.net/showthread.php?t=19489&quot; rel=&quot;noreferrer&quot;&gt;zone-five.net&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This tug is powered by a diesel engine and controlled using a joystick. In order to be useful in the confines of the deck, the tug can rotate with a zero turning radius. The operation is pretty much similar to the other tugs- the tug is moved so that it lifts up the nosewheel, facilitating the aircraft movement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The French, on the other hand use remotely controlled mototk tugs on board de Gaulle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Ji7oD.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Ji7oD.jpg&quot; alt=&quot;mototok&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://www.mototok.com/military.php&quot; rel=&quot;noreferrer&quot;&gt;mototok.com&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-05-23T12:35:03.293" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27732" PostTypeId="1" CreationDate="2016-05-23T12:57:57.417" Score="8" ViewCount="813" Body="&lt;p&gt;Are there any limitations for myopia (-number) for a pre-eye refraction surgery for a class 1 medical certificate? I live in India &amp;amp; I have -6.5 &amp;amp; -7.5 in the left &amp;amp; right eye respectively.&lt;/p&gt;&#xA;" OwnerUserId="15079" LastEditorUserId="62" LastEditDate="2016-05-23T13:29:34.067" LastActivityDate="2017-08-21T10:53:52.697" Title="What are the limits on myopia for a pre-eye refraction surgery for a class 1 medical certificate?" Tags="&lt;medical&gt;&lt;dgca-india-regulations&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27733" PostTypeId="2" ParentId="27726" CreationDate="2016-05-23T13:03:53.683" Score="9" Body="&lt;p&gt;I'm not sure why &quot;Naval jets land by catching a wire that brakes them hard. They may also takeoff with a catapult, which is some running device that pulls the nose gear forward at high g's.&quot; would make you question your assumption that carrier &quot;landings are 'rough'&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to &lt;a href=&quot;https://aviation.stackexchange.com/a/27727/5517&quot;&gt;Jan Hudec's description of the landing process&lt;/a&gt;, your statement about takeoffs is reasonably accurate, as well. According to Wiki, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_catapult#Steam_catapults_types&quot; rel=&quot;nofollow&quot;&gt;C-13-1 catapult&lt;/a&gt; (used on many Nimitz class carriers) can shoot 80,000 lbs to 140 knots in 310 feet generating 2.81g with a total force of 225,140 lb (Thanks reirab!). All that stress goes through the nose gear.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Between the launch and the landing, there are considerably higher forces on the undercarriage of the plane, thus it needs to be considerably stronger than that of an equivalent land-based aircraft.&lt;/p&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="5517" LastEditDate="2016-05-24T12:01:30.210" LastActivityDate="2016-05-24T12:01:30.210" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27734" PostTypeId="1" AcceptedAnswerId="27742" CreationDate="2016-05-23T13:07:18.510" Score="7" ViewCount="3164" Body="&lt;p&gt;I'm a student pilot having trouble with landings, and problems are occurring in the pattern on base and on final;  I am either too high or too low. As a result, I feel I have lost confidence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I feel like I am relying on my instructor to tell me what to do next instead of me flying the plane. How do I improve this situation?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, it has been suggested that I stop using the simulator as this is teaching me bad habits.&lt;/p&gt;&#xA;" OwnerUserId="15080" LastEditorUserId="14661" LastEditDate="2016-05-23T18:51:24.690" LastActivityDate="2016-05-24T13:53:03.510" Title="How can I stop being too high or low when on base and final?" Tags="&lt;landing&gt;&lt;flight-training&gt;&lt;takeoff&gt;&lt;traffic-pattern&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27735" PostTypeId="2" ParentId="27728" CreationDate="2016-05-23T13:57:54.167" Score="11" Body="&lt;p&gt;Birds have integrated active control systems that rely on several sensors to adjust the control surfaces to stabilize the flight. Since it is very difficult (perhaps impossible) to study the aerodynamic properties of the bird independently from its control system it is hard to make any claims on the static or dynamic stability of a bird. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;What can be said is that from a control system point of view, most birds are observable, controllable and stabilizable in flight. This does not apply to the class of &lt;a href=&quot;https://en.wikipedia.org/wiki/Flightless_bird&quot; rel=&quot;nofollow noreferrer&quot;&gt;flightless birds&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are interested in the similarities in aerodynamics between insects, birds and aircraft I recommend getting a copy of &quot;&lt;a href=&quot;https://mitpress.mit.edu/books/simple-science-flight&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Simple Science of Flight; from insects to jumbo jets&lt;/a&gt;&quot; by Henk Tennekes, an  Emeritus Professor of Aerospace Engineering at Pennsylvania State University. &lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;After sitting in the garden on a sunny afternoon, observing various bird species and tinkering a bit more on the subject I actually think that many birds are unstable. Especially the smaller species that fly in the garden through bushes and trees, but also those that hunt for flying insects, are capable of extreme rapid changes in direction of flight; they are very agile. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Stability and extreme manoeuvrability are difficult to combine. In fact &lt;a href=&quot;https://aviation.stackexchange.com/q/8049/19&quot;&gt;modern jet fights are designed to be unstable to improve their manoeuvrability&lt;/a&gt;. They then need a computerized control system to stabilize them. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;An online search showed that some research has been done on the field of flight stability of birds Petter Krus of the Linköping University in Sweden has published an article on &lt;a href=&quot;http://arc.aiaa.org/doi/abs/10.2514/6.1997-5653&quot; rel=&quot;nofollow noreferrer&quot;&gt;Natural methods for Flight Stability in Birds&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Abstract:&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;There is a stark contrast between the behaviour of flying man-made&#xA;  artifacts and the effortless elegance of bird flight. In this paper,&#xA;  mechanisms are proposed that seems to be at least related to the way&#xA;  birds fly when they are gliding (the no propulsion case). It is&#xA;  recognized that biological structures and actuator systems (muscles)&#xA;  are characterized by a great deal of compliance that produce a&#xA;  completely different dynamic behaviour of flight. In this paper it is&#xA;  demonstrated how this can be applied on a geometrically unstable&#xA;  bird-like configuration. The result is that geometrically unstable&#xA;  configurations can be stabilised without the need of rate gyros and/or&#xA;  accelerometers. Although the bird might have a fast acting control&#xA;  system for flight control, it is unlikely that it is fast enough for&#xA;  active stabilisation of the short period oscillation, and this is&#xA;  unnecessary with the model described here, which only requires&#xA;  stabilisation of the long period oscillation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In his introduction he also briefly refers to the work of Tennekes, which does not include much about the stability of birds. Also in the introduction he observes that birds have a cambered wing and must have an aft centre of gravity. This combination makes the bird unstable (if it were a rigid body). &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-05-27T13:21:28.867" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27736" PostTypeId="2" ParentId="27718" CreationDate="2016-05-23T14:53:58.627" Score="2" Body="&lt;p&gt;In addition to the examples TomMcW cites, &lt;a href=&quot;https://www.bea.aero/uploads/tx_elydbrapports/BEA2015-0125.en-LR.pdf&quot; rel=&quot;nofollow&quot;&gt;the final report into Germanwings&lt;/a&gt; lists on pp 72-73 several related incidents. The list includes the JetBlue 191 mentioned by TomMcW. Similar events occurred on a Egypt Air flight in 1999 where the relief co-pilot flew the aircraft into terrain despite the captain trying to override his input (on a non-fly-by-wire aircraft), and on a Royal Air Maroc flight in 1996, and a Japan Airlines flight in 1982. In all of those cases, the cause was (or was suspected to be) a psychiatric problem rather than a simple argument.&lt;/p&gt;&#xA;" OwnerUserId="998" LastActivityDate="2016-05-23T14:53:58.627" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27737" PostTypeId="1" CreationDate="2016-05-23T14:56:18.307" Score="4" ViewCount="970" Body="&lt;p&gt;Let's say you have an EASA-style logbook with European flight time, and then, you start flying in the USA, so you buy an FAA-style logbook and begin logging hours for your flights in the USA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't think it is a good practice to mix foreign hours, since &lt;em&gt;if both logbooks are still open&lt;/em&gt; you can have inaccuracies and inconsistencies in the transferred hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;The question is:&lt;/em&gt;&lt;/strong&gt; is it mandatory to bring your flying hours from the European logbook to the &quot;AMOUNT FORWARD&quot; section in the American logbook, or is it optional?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is a good practice if you have multiple foreign logbooks?&lt;/p&gt;&#xA;" OwnerUserId="14891" LastEditorUserId="14661" LastEditDate="2017-01-27T05:58:07.630" LastActivityDate="2017-01-27T05:58:07.630" Title="How should I log total hours flown in different countries?" Tags="&lt;logging&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27739" PostTypeId="2" ParentId="27737" CreationDate="2016-05-23T16:02:57.447" Score="7" Body="&lt;p&gt;&lt;strong&gt;Is it mandatory to bring your flying hours from the European logbook to the &quot;AMOUNT FORWARD&quot; section in the American logbook?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;No, it is not mandatory to bring your flying hours from the European logbook to the &quot;AMOUNT FORWARD&quot; section in the American logbook.&lt;/em&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the USA, logging time is not required at all other than information for required recent experience and check ride prerequisites.  Also, there is no reason the EASA logbook is not an acceptable document for that purpose so long as it contains the needed information such as landings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What is a good practice if you have multiple foreign logbooks?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consolidate them into one logbook that best fits the system in which you do most of your flying and keep only specific additional requirements for the other systems logged elsewhere.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you need to keep the total flight hours separate, I would use one of the customizable columns that I have seen in most logbooks and label it with whichever system you fly in less.  Then you can simply subtract that column from your grand total to deduce the other system's total time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although, based on how much I get picked on by my German friends for not using the metric system, I could understand the assumption that we must be different.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-23T18:26:26.917" LastActivityDate="2016-05-23T18:26:26.917" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27740" PostTypeId="1" CreationDate="2016-05-23T16:14:32.213" Score="0" ViewCount="80" Body="&lt;p&gt;Newton's laws state that for every force there is an equal and opposite force. I'm thinking of an airplane like a simple system: we put x force in and get y force out. An airplane has the force from thrust and the force from gravity, I understand this. The force of gravity is constant and equals the airplane's mass times gravity. It seems like airplanes cheat newton's laws. Somehow an airplane is only generating about 1/10th the force of gravity, but it is able to use this thrust force to provide the force equal to the gravity force plus a force against the air resistance (drag). I have heard lift explained in Newtons laws as the downwash of air and how the total mass x acceleration of the air in the downwash equals the mass x gravity of the airplane. In short, the airmass acceleration generated by the propeller &amp;lt; than airmass accelerated by the wing: how does this make sense? What am I missing?&lt;/p&gt;&#xA;" OwnerUserId="14825" LastEditorUserId="14825" LastEditDate="2016-05-25T02:07:32.077" LastActivityDate="2016-05-25T02:07:32.077" Title="Lift and Newton's laws" Tags="&lt;lift&gt;" AnswerCount="0" CommentCount="6" FavoriteCount="0" ClosedDate="2016-05-23T16:50:12.107" ContentLicense="CC BY-SA 3.0" />
  <row Id="27741" PostTypeId="1" CreationDate="2016-05-23T19:03:11.283" Score="0" ViewCount="320" Body="&lt;p&gt;What are the flying accommodations in Silicon Valley for private pilots? I notice there are two pretty sizable airports: Moffett Airfield and Mineta San Jose. Do both accept GA flights and have landing fees below $50?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What about instruction? Where do pilots generally go for instruction in the San Jose-Palo Alto area?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="19" LastEditDate="2016-07-06T16:12:53.347" LastActivityDate="2016-07-06T16:12:53.347" Title="What are the flying accommodations in Silicon Valley for private pilots?" Tags="&lt;airport&gt;&lt;flight-training&gt;&lt;usa&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27742" PostTypeId="2" ParentId="27734" CreationDate="2016-05-23T19:07:46.013" Score="11" Body="&lt;p&gt;I think one thing that does not get emphasized enough:&lt;br&gt;&#xA;&lt;strong&gt;Pilots do not land airplanes!&lt;/strong&gt;&lt;br&gt;In fact, we try to keep the airplane flying as long as possible!  We systematically rob the airplane of energy (energy from engine power, energy from airspeed, energy from altitude) until the plane can no longer fly, and settles gently on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But even as the plane is landing, the pilot is still trying to coax it back into the air to remove as much energy as possible.  A big student mistake is to point the airplane at the runway, and try to &lt;em&gt;force&lt;/em&gt; it to land there.  That leads to landings too fast, too high, big bounces, porpoising, and sometimes nose-in crashes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So don't think about &lt;em&gt;&quot;how am I going to land this thing?&quot;&lt;/em&gt;  Instead think about &lt;em&gt;&quot;How am I going to remove more energy from the equation to lose altitude and airspeed?&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A landing is a series of precise targets you are aiming to hit, each with less energy than the last one (but each one still with enough energy to keep flying and be safe)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Each target consists of Position (horizontal and altitude), airspeed, and descent rate.  You hit each of these targets at 3 different points on a square (abeam the numbers, downwind-to-base, and base-to-final) Hitting a target that consists of a position + airspeed + descent rate is not easy! But the more precisely you can hit each target, the easier the next part is.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Although I hope I'm repeating the same instructions you've already heard, for the sake of the Site, let me re-iterate the standard instructions for a C-172.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Be level at TPA (airport + 1000 feet), and at a cruise speed of approximately 100 kts.  The runway should be approx 3/4 of the way up your strut.&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When you are abeam the numbers, Carb Heat (if applicable), throttle back to approx 1,600 RPM, and pull-back as necessary to maintain altitude (the consequence will be that you slow down).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Watch your speed, altitude and position.  Drop flaps 10&amp;deg; when speed allows, and aim to hit a speed of 85 kts, an altitude loss of 250 feet, and have the numbers at 45&amp;deg; behind you, all at the same time.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Turn the corner to base, using approximately 30&amp;deg; of bank angle.  Continue to reduce speed (by pulling back) to hit 75 kts, and drop altitude another 250 ft. (you're now 500 ft above the runway).  Add Flaps 20 when appropriate.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Turn the corner to final.  You can &quot;oval&quot; your turn if you are undershooting the centerline, but do NOT over-bank if you have overshot the centerline.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Aim for the centerline, acquire a PAPI/VASI, keep an eye on your airspeed relative to approach speed (68 kts).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Watch 3 and ONLY 3 things:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airspeed (Slowing towards 68 kts)&lt;/li&gt;&#xA;&lt;li&gt;Centerline (left? right? on target?)&lt;/li&gt;&#xA;&lt;li&gt;Slope (PAPI/VASI? Light configuration).&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Keep repeating &quot;Airspeed, Centerline, Slope&quot; out loud, describe if you're too far/too close on each one, and describe how you're going to correct.  For example: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;Airspeed: 75 kts; too fast; pulling back to slow down&quot;&lt;/li&gt;&#xA;&lt;li&gt;&quot;Centerline: Left of center; coming slightly right&quot;&lt;/li&gt;&#xA;&lt;li&gt;&quot;Slope: 3 red+1 white is too low; adding power to slow descent&quot;&lt;/li&gt;&#xA;&lt;li&gt;(repeat!)&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;When the runway is made, drop final flaps, engine to idle, and prepare to flare when you're about 10-15 feet, and hopefully right at the numbers.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Remember that your altitudes are 1000, 750, 500, touchdown.&lt;br&gt;&#xA;And your airspeeds are 85, 75, 65.&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2016-05-24T13:53:03.510" LastActivityDate="2016-05-24T13:53:03.510" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27743" PostTypeId="2" ParentId="27734" CreationDate="2016-05-23T19:18:35.467" Score="4" Body="&lt;p&gt;The problem with simulators is that they do not have a very wide field of view, so it is hard to train your eye using a simulator. If they develop simulators with full VR panoramic vision someday, that will be much more useful. Some walk-in military simulators are like this, but normal students do not have access to these.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you look down at the runway, it should be at the right angle. When you go onto final that angle is 3-degrees which is a 20:1 distance/height ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically the way it works is as you go downwind you look left (or right) and espy the numbers, if they too are low (ie you are high) you keep heading downwind and gradually descending until it looks right. To learn what &quot;looks right&quot; learn all the distances and altitudes at your home airport. If you know the geometry of your home airport you should know EXACTLY where to turn for any given altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It sounds to me like you do not know this. You need to sit down with satellite photos of the field, a ruler, pencil, and calculator and start measuring until you really know all the angles and measurements exactly. Every good pilot does this when they are a student. Once you learn it for one airport your eye will know what is right and can land anywhere.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is really a homework and serious study problem. Don't just jump in a plane and wing it--that's how bad, sloppy pilots get made. You need to sit down and master it before you even drive to the airport. I was just sitting with a student yesterday and he showed me his notebook. Wow! Looked like engineering drawings. He had every dimension and angle all plotted out on graph paper in incredibly neat writing. He is going to be a really good pilot someday. That is the kind of behavior you need to emulate.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-05-23T20:29:36.873" LastActivityDate="2016-05-23T20:29:36.873" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27744" PostTypeId="1" AcceptedAnswerId="27753" CreationDate="2016-05-23T20:25:51.440" Score="5" ViewCount="1284" Body="&lt;p&gt;Let's consider the next turboprop arrangement:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/9IRsz.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9IRsz.jpg&quot; alt=&quot;Energy-Balance-Shaft-Turboprop&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What I am looking for&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I am looking for an &lt;em&gt;equation that involves&lt;/em&gt; $\dot{W}_T$, $\dot{W}_C$ and $\dot{W}_P$ (i.e. the power done by each component). This needs to be done through an energy balance in the shaft.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;What we know&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;We know that the shaft has an efficiency of $\eta_{\text{shaft}}$, and the gearbox has an efficiency of $\eta_{\text{box}}$.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My try (#1)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since energy is derived from the turbine, we adopt the convention $\dot{W}_T&amp;gt;0$, therefore $\dot{W}_P, \dot{W}_C &amp;lt; 0$. In other words, &lt;em&gt;energy is required&lt;/em&gt; to move the compressive devices.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following the definition of mechanical efficiency: $$\boxed{\eta_{\text{shaft}}=\dfrac{-\dot{W_C}-\dot{W_P}}{\dot{W_T}}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I don't know how to incorporate the efficiency $\eta_{\text{box}}$ into this equation. This led me to try and find another expression.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My try (#2)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Following an hydraulic analogy for the power, I thought that &lt;em&gt;whatever power the turbine generates needs to be invested in:&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Increasing the temperature of the bearings of the main shaft (because the shaft is not ideal and has an efficiency of $\eta_{\text{shaft}}$).&lt;/li&gt;&#xA;&lt;li&gt;Moving the compressor.&lt;/li&gt;&#xA;&lt;li&gt;Increasing the temperature of the gearbox (because the box is not ideal and has an efficiency of $\eta_{\text{box}}$).&lt;/li&gt;&#xA;&lt;li&gt;Moving the propeller.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Following this thinking, I can intuitively find this next equation (which I don't know if is correct or not): $$\boxed{\eta_{\text{shaft}}\times \dot{W}_T = -\dot{W}_C-\dfrac{\dot{W}_P}{\eta_{\text{box}}}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The thing is I don't know if I assigned the efficiency $\eta_{\text{box}}$ correctly or not. Is there an easier way (i.e. less intuitive/more mechanical way) to apply the energy equation? What if we had 2 or more shafts?&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="19" LastEditDate="2016-07-06T16:08:11.187" LastActivityDate="2016-07-06T16:08:11.187" Title="What is the equation for the energy balance between turbine, compressor and propeller?" Tags="&lt;propeller&gt;&lt;turbine&gt;&lt;compressor&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27745" PostTypeId="2" ParentId="27741" CreationDate="2016-05-23T20:41:24.133" Score="3" Body="&lt;p&gt;Moffett Field is still primarily a Federal airfield. They'll take some corporate jets, but not GA, and &lt;a href=&quot;https://sites.google.com/a/pv-nuq.com/nuq/forms&quot; rel=&quot;nofollow&quot;&gt;prior permission&lt;/a&gt; is required. All requests go through Planetary Ventures LLC, which owned by Google.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;San Jose is a large international airport, but it appears to have no landing fee, though you'll pay a ramp fee unless it's waived. Some &lt;a href=&quot;https://www.airnav.com/airport/KSJC/ATLANTIC#c&quot; rel=&quot;nofollow&quot;&gt;AirNav reviews of the FBO&lt;/a&gt; give you an idea of what to expect, and you could contact them for further information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are a number of GA airports to choose from though. Including:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://www.countyairports.org/rhv.html&quot; rel=&quot;nofollow&quot;&gt;Reid-Hillview&lt;/a&gt; &lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.airnav.com/airport/KPAO&quot; rel=&quot;nofollow&quot;&gt;Palo Alto&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://www.airnav.com/airport/KSQL&quot; rel=&quot;nofollow&quot;&gt;San Carlos&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;All of these airports have flying clubs and should offer instruction.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Along with others somewhat further away (a few examples include Half Moon Bay to the Northwest, San Martin to the south, Hayward Executive and Oakland International to the east), depending on where exactly you'd like to be. &lt;/p&gt;&#xA;" OwnerUserId="5568" LastActivityDate="2016-05-23T20:41:24.133" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27746" PostTypeId="1" CreationDate="2016-05-23T20:59:17.617" Score="3" ViewCount="1174" Body="&lt;p&gt;What is the specific aerodynamic effect which requires one to hold into-wind aileron to keep the wings level during takeoff in a B737? (i.e. dihedral or sweep)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Subsequently, what is the aerodynamic reason for having to increase that into- wind aileron input immediately after Takeoff.&lt;/p&gt;&#xA;" OwnerUserId="15087" LastEditorUserId="11787" LastEditDate="2016-06-22T15:41:35.563" LastActivityDate="2016-06-27T17:44:29.103" Title="What are the effects of crosswind on takeoff?" Tags="&lt;aerodynamics&gt;&lt;takeoff&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27747" PostTypeId="2" ParentId="27746" CreationDate="2016-05-23T21:14:59.590" Score="0" Body="&lt;p&gt;When a crosswind hits an aircraft it affects the windward side more because the fuselage shadows the leeward wing. Therefore, what happens is that the wind tends to lift up the wing on the windward side. This only happens when the plane is on the ground because what happens is that the wind fills the space between the ground and the wing and pressurizes this area. This pressurization is called &lt;em&gt;ground effect&lt;/em&gt;. If the wind is a headwind (such as when landing), then the area under both wings is equally pressurized, but if there is a crosswind, then the windward side will be pressurized harder and tend to lift up the wing. In such cases the pilot needs to use the aelirons to counteract that effect.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that any upgust can have a similar effect. For example, when landing on a windy day, the wind will hit the ground and move upwards creating upgusts. These can hit your wing and flip you over, if the aircraft is light. Therefore, when landing a pilot will always be wing down to the wind.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-23T21:14:59.590" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27748" PostTypeId="2" ParentId="27434" CreationDate="2016-05-23T21:29:24.613" Score="1" Body="&lt;p&gt;the following information only concerns the A320.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Flight Augumentation (FAC) performs the following functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Yaw damper&lt;/li&gt;&#xA;&lt;li&gt;Rudder travel limiting &lt;/li&gt;&#xA;&lt;li&gt;Monitoring of the flight envelope and computation of maneuvering speed&lt;/li&gt;&#xA;&lt;li&gt;Yaw autopilot order &lt;/li&gt;&#xA;&lt;li&gt;Bite fuction of the AFS&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However to my knowledge, the Flight augmentation Computers, (FACs) do not calculate the Gross-weight. In fact it's the single or dual channel weight and balance system utilizing six weight sensing elements attached to mounting surfaces in the main and nose landing gear. these transducers are driven by a digital computer (WBC). The WBC computes the aircraft center of gravity and the gross weight which is communicated to the flight crew via the Display Management Computers (DMCs) the ECAM.  &lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="15062" LastEditDate="2016-05-23T21:37:09.810" LastActivityDate="2016-05-23T21:37:09.810" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27749" PostTypeId="2" ParentId="27726" CreationDate="2016-05-23T21:50:32.900" Score="3" Body="&lt;p&gt;It's the first reason you list: the aircraft hit the deck hard. It's not just the undercarriage; the whole airframe has to be ruggedized to withstand the greater shock of carrier landings.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-23T21:50:32.900" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27750" PostTypeId="2" ParentId="27685" CreationDate="2016-05-23T23:11:12.740" Score="4" Body="&lt;p&gt;Very rarely will a manual &lt;em&gt;directly&lt;/em&gt; be used by flight crew for calculation of fuel uplift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight crews generally receive an Operational Flight Plan prepared by the operator (the airline), or an agent of the operator, where calculations have been made for how much fuel will be required for the specific flight, and necessary reserves. Flight crew may elect to revise the fuel required to provide additional margin for weather, traffic or other factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The calculations made for the Operational Flight Plan are made with flight planning software, which in its turn uses data from performance manuals/data sets, and takes a large amount of parameters into account (routing (duh!), wind, flight altitude, speed, aircraft weight, load distribution (c.g.), alternate airport availability etc). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flight crew &lt;strong&gt;can&lt;/strong&gt; however make simplified fuel calculations using the FPPM for the aircraft type (Flight Performance and Planning Manual) (Boeing). The flight profile is however generally quite limited to a few climb/cruise/descent schedules, and the data is not what would be used on a normal line day. Distribution of FPPM (and other manuals) is generally restricted. If you however would come across a replica of a FPPM, you could probably make a usable fuel calculation using the instructions within it.&lt;/p&gt;&#xA;" OwnerUserId="7172" LastActivityDate="2016-05-23T23:11:12.740" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27751" PostTypeId="1" CreationDate="2016-05-24T00:05:26.800" Score="1" ViewCount="172" Body="&lt;p&gt;With those many websites that compare flights we usually have the opportunity to chose between different paths to reach the final destination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Should the type of plane influence the decision? Ex. If I see that one company uses a Boeing 787 instead of a Boeing 767 or an Airbus A330-300, does that influence the travel experience in a perceivable way (In terms of turbulence attenuance, noise reduction, smoothness of flight, different types of landing/take off)?&lt;/p&gt;&#xA;" OwnerUserId="15089" LastEditorUserId="15089" LastEditDate="2016-05-24T00:15:28.637" LastActivityDate="2016-05-24T00:31:54.817" Title="Should the type of plane influence my travel choice?" Tags="&lt;airliner&gt;&lt;airlines&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-05-24T02:22:29.317" ContentLicense="CC BY-SA 3.0" />
  <row Id="27752" PostTypeId="2" ParentId="27751" CreationDate="2016-05-24T00:31:54.817" Score="3" Body="&lt;p&gt;As a general rule, not really, though there may be some factors that could cause you to consider it as part of your decision-making.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Some short-haul routes may be served by aircraft of significantly different sizes. For instance, some flights between San Francisco and Los Angeles may be on a Boeing 737, while others are on a CRJ Regional Jet. Still others may be offered on a turboprop like the &lt;a href=&quot;https://en.wikipedia.org/wiki/Bombardier_Dash_8&quot; rel=&quot;nofollow noreferrer&quot;&gt;Dash 8&lt;/a&gt; or the even smaller &lt;a href=&quot;https://en.wikipedia.org/wiki/Beechcraft_1900&quot; rel=&quot;nofollow noreferrer&quot;&gt;Beechcraft 1900&lt;/a&gt; (or even smaller aircraft, especially serving remote areas). Even those who aren't afraid of flying may be uncomfortable on small &quot;puddle jumper&quot; aircraft, as the seats and headroom are usually physically small and they can be more impacted by turbulence. Such aircraft can also require standard carry-on bags to be checked at the gate (they are usually returned to you at the gate on arrival), as lack large overhead bins.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The Boeing 787 Dreamliner can be &lt;a href=&quot;https://aviation.stackexchange.com/questions/1728/does-the-b787-dreamliner-operate-with-higher-cabin-pressure&quot;&gt;pressurized to a lower cabin altitude&lt;/a&gt; and has a higher level of humidity than is typical. Efforts were made to lower cabin noise as well. This can lead to a more comfortable flight. Many of these enhancements may be carried over into future next-generation aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;There may be differences in the cabins depending on the aircraft model, especially in premium classes. For instance, first class passengers on Lufthansa may have a separate bed on Boeing 747 aircraft, while those on Lufthansa's A340 will have to make do with sleeping on bedding atop their luxurious seat. Emirates business class is supposedly far better on the A380 (which includes a bar in the back) than the 777, though which you get mostly depends on your route. In other cases, an airline may be rolling out a new premium seat design, which is only available on some aircraft types. While the differences are less pronounced in economy, there may be variations in seat pitch (legroom) and configuration (2-5-2 vs 3-4-3 for example) that can make a significant difference in comfort.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Some people prefer newer aircraft. This can be difficult to guarantee by type alone though, as many aircraft have been produced over a period of decades. Even older aircraft have to go through a rigorous inspection and maintenance procedure though.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That said, most people are choosing their flights based on factors like price, route/time, and frequent flyer membership. Type of aircraft is usually pretty low on the priority list unless you're an enthusiast determined to fly a certain new model. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also note that aircraft type is never guaranteed, and carriers reserve the right to make substitutions for operational reasons without notice. &lt;/p&gt;&#xA;" OwnerUserId="5568" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-24T00:31:54.817" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27753" PostTypeId="2" ParentId="27744" CreationDate="2016-05-24T01:15:44.273" Score="3" Body="&lt;p&gt;Since the compressor loses a fraction of the turbine's work through the shaft, but is unaffected by the gearbox, but the prop experiences losses from the shaft and the gearbox, this equation should be what you need:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$\dot{W_t}=\frac{-\dot{W_c}}{\eta_{shaft}}+\frac{-\dot{W_p}}{\eta_{shaft}*\eta_{gearbox}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is the same as your attempt two (with some algebra).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As you add more efficiencies to a component, you would just continue to multiple the all $\eta$'s together to get the total efficiency of that component, since efficiencies are multiplicative and the associative property of multiplication.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-05-24T01:15:44.273" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27754" PostTypeId="2" ParentId="12224" CreationDate="2016-05-24T01:17:12.170" Score="3" Body="&lt;p&gt;The Flight Augmentation (FAC) performs the following functions:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Yaw damper  Rudder travel limiting&lt;/li&gt;&#xA;&lt;li&gt;Monitoring of the flight envelope and computation of maneuvering speed&lt;/li&gt;&#xA;&lt;li&gt;Yaw autopilot order&lt;/li&gt;&#xA;&lt;li&gt;Bite fuction of the AFS &lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;The trim actuator, the yaw damper servoactuators and the travel limitation unit are normally controlled by the flight Augmentation Computer (FAC 1) and FAC 2 being in standby.&#xA;The rudders are controlled either mechanically from the pedals or electrically when the auto pilot is engaged. Therefore if both FACs fail, the rudder control remains unaffected. However the autopilot is no longer available.&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="19" LastEditDate="2016-05-24T06:04:44.993" LastActivityDate="2016-05-24T06:04:44.993" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27755" PostTypeId="2" ParentId="14772" CreationDate="2016-05-24T02:02:57.420" Score="1" Body="&lt;p&gt;The Flight management and guidance system (FMGC) performs the following functions:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Autopilot&lt;/li&gt;&#xA;&lt;li&gt;Flight director &lt;/li&gt;&#xA;&lt;li&gt;autothrust&lt;/li&gt;&#xA;&lt;li&gt;flight management &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The FMGS sends the thrust commands for the autothrust function to the ECU1/EEC1 to set the thrust command on the engine 1. ECU2/EEC2 to set the thrust command on the engine 2.&lt;/p&gt;&#xA;" OwnerUserId="15062" LastActivityDate="2016-05-24T02:02:57.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27756" PostTypeId="2" ParentId="24160" CreationDate="2016-05-24T02:22:00.190" Score="1" Body="&lt;p&gt;When the angle of attack limit is reached, a value which is dependent on the configuration and longitudinal wind gradient, the FMGC receives the order from the FAC. This order is only taken into account by the FMGC, if:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Landing gear shock absorbers are extended at takeoff&lt;/li&gt;&#xA;&lt;li&gt;and up to 100 ft at landing &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;If these conditions are met, the A/THR is engaged, and the Alpha floor protection is activated. The A/THR is commanded max. consequently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only way to cancel alpha floor is by disengaging the A/THR function.&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="7532" LastEditDate="2016-05-24T03:11:15.340" LastActivityDate="2016-05-24T03:11:15.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27757" PostTypeId="2" ParentId="16292" CreationDate="2016-05-24T02:33:38.990" Score="1" Body="&lt;p&gt;The MATOW (max allowable takeoff weight) isn't only limited it's structural weight limit (MTOW) but is absolutely limited by other factors.  For transport category aircraft these other factors can limit max allowable takeoff weight.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Max structural weight&lt;/li&gt;&#xA;&lt;li&gt;Brake energy for takeoff&lt;/li&gt;&#xA;&lt;li&gt;Wheel brake cooling limits&lt;/li&gt;&#xA;&lt;li&gt;Maximum tire speed&lt;/li&gt;&#xA;&lt;li&gt;Required gradients for first, second and final segment climb to 1500' AGL.&lt;/li&gt;&#xA;&lt;li&gt;Required runway distance to verify the takeoff weight will produce a runway distance below all runway declared distances.&lt;/li&gt;&#xA;&lt;li&gt;Obstacles in the takeoff flight path&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The pilot in command is required to verify they do not takeoff above any of those limits.  The airlines have dispatchers that will calculate this information.  If a mistake is made, it is possible to be loaded above the max allowable takeoff weight and not realize it.  Most of the list above is accounting for an engine failure below or above the decision speed.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-05-24T02:33:38.990" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27758" PostTypeId="2" ParentId="7500" CreationDate="2016-05-24T02:40:53.520" Score="0" Body="&lt;p&gt;During the climb there is a point where the climb is continued by maintaining a fixed Mach number. This point during the climb is called the cross over altitude. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;M=TAS/a&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;M: Mach number&lt;/li&gt;&#xA;&lt;li&gt;TAS: True Airspeed&lt;/li&gt;&#xA;&lt;li&gt;a: Speed of sound&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since the speed of sound is decreasing with decreasing OAT, the TAS has to decrease as well to keep the Mach number constant. However although TAS is decreasing the aircraft is not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/BTKzz.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BTKzz.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;(&lt;a href=&quot;http://www.pprune.org/tech-log/360114-inc-perf-above-cross-over.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;pprune.org&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="14897" LastEditDate="2017-02-08T15:55:07.023" LastActivityDate="2017-02-08T15:55:07.023" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27760" PostTypeId="1" AcceptedAnswerId="27764" CreationDate="2016-05-24T03:42:02.540" Score="5" ViewCount="3644" Body="&lt;p&gt;Since the L/D ratio remains unaffected by the aircraft weight, will there be any effect to the gliding range?&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="1467" LastEditDate="2016-05-24T10:19:11.920" LastActivityDate="2016-05-24T10:19:11.920" Title="How does aircraft weight affect the glide performance?" Tags="&lt;aircraft-performance&gt;&lt;weight-and-balance&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="2" ClosedDate="2016-05-24T11:51:22.440" ContentLicense="CC BY-SA 3.0" />
  <row Id="27761" PostTypeId="1" CreationDate="2016-05-24T04:55:20.657" Score="2" ViewCount="221" Body="&lt;p&gt;My airline's vertical navigation data isn't certified for use and is considered 'advisory' only.  But, 90% of the time it provides highly accurate data.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some instructors at my company contend that 'localizer recommended altitudes' are required to be used as the primary / only reference for a CANPA style continuous descent to our DDA (derived decision altitude) on localizer approaches. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I contend that any method chosen for a descent to DDA is purely technique and as long as our advisory VNAV data is backed up with other data &amp;amp; looks accurate, there's nothing wrong with using it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are localizer recommended altitudes regulatory in any way?  Is it legal to use an 'advisory' Vnav data to fine-tune your descent from the FAF to DDA? Any links, references, or regulations you can point me to on the subject would also be greatly appreciated.&lt;/p&gt;&#xA;" OwnerUserId="15092" LastEditorUserId="15092" LastEditDate="2016-05-24T14:49:48.697" LastActivityDate="2017-01-08T04:29:24.083" Title="Is it acceptable to use VNAV data in lieu of localizer recommended altitudes?" Tags="&lt;instrument-procedures&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27762" PostTypeId="2" ParentId="13904" CreationDate="2016-05-24T06:12:27.177" Score="2" Body="&lt;p&gt;When both engines have failed, the A320 reverts to alternate law. However the pitch law is replaced by the direct law upon landing gear extension. The side stick movement directly controls the elevator position. It means that side stick input is proportional to flight control output. The THS is mechanically controlled from the trim control wheel. No protection is included.&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="15062" LastEditDate="2016-05-24T06:17:28.860" LastActivityDate="2016-05-24T06:17:28.860" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27763" PostTypeId="1" AcceptedAnswerId="27779" CreationDate="2016-05-24T07:26:09.380" Score="13" ViewCount="2778" Body="&lt;p&gt;Increasingly, modern types do not use plug doors to save complexity and weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As far as I know, the doors automatic/manual interlock only controls whether the slide inflates when the door is opened.  The doors have electrically powered locks and EICAS alerts to show unlocked doors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, anything electrical can and does fail.  What fail safe protections are in place to prevent non-plug doors from being opened in flight?&lt;/p&gt;&#xA;" OwnerUserId="595" LastEditorUserId="19" LastEditDate="2017-05-15T08:09:09.993" LastActivityDate="2017-05-15T08:09:09.993" Title="What fail safe protections exist to prevent non-plug type cabin doors opening in flight?" Tags="&lt;aircraft-design&gt;&lt;safety&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27764" PostTypeId="2" ParentId="27760" CreationDate="2016-05-24T08:00:21.253" Score="5" Body="&lt;p&gt;The gliding slope, which equals $D/L$, does not change with weight. Hence, starting from a given height $h$, the &lt;em&gt;longest&lt;/em&gt; gliding distance will be $d = h \cdot max(L/D) = h \cdot max(C_L/C_D)$, i.e., independent of weight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the gliding speed, and, consequently, the gliding time, do change with weight, and significantly. If $C_{L,max}$ is the lift coefficient when $C_L/C_D$ is maximal, the gliding speed at best slope, $\bar{V}$, is obtained from $W = (1/2) \cdot rho \cdot \bar{V}^2 \cdot S_{ref} \cdot  C_{L,max}$.&lt;/p&gt;&#xA;" OwnerUserId="15036" LastEditorUserId="1467" LastEditDate="2016-05-24T09:06:31.533" LastActivityDate="2016-05-24T09:06:31.533" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27766" PostTypeId="1" AcceptedAnswerId="27767" CreationDate="2016-05-24T15:15:44.700" Score="1" ViewCount="370" Body="&lt;p&gt;Which country requires the fewest number of flight hours for pilot certification?&lt;/p&gt;&#xA;" OwnerUserId="15013" LastEditorUserId="14661" LastEditDate="2016-05-24T17:27:35.980" LastActivityDate="2016-05-24T17:27:35.980" Title="Which country has the lowest flight time requirement for the issuance of a pilot certificate?" Tags="&lt;flight-training&gt;&lt;pilot-certification&gt;&lt;ppl&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-05-24T18:06:16.123" ContentLicense="CC BY-SA 3.0" />
  <row Id="27767" PostTypeId="2" ParentId="27766" CreationDate="2016-05-24T16:14:03.000" Score="2" Body="&lt;p&gt;Here in the US you can get your &lt;a href=&quot;https://www.aopa.org/advocacy/advocacy-briefs/frequently-asked-questions-about-sport-pilot&quot; rel=&quot;nofollow noreferrer&quot;&gt;sport pilot in 20 hours&lt;/a&gt; but that is a pretty heavily limited license, your basic VFR PPL will require at least &lt;a href=&quot;https://aviation.stackexchange.com/questions/1199/what-are-the-requirements-to-take-the-private-pilot-check-ride&quot;&gt;40 hours here in the US&lt;/a&gt;. You should note that this is flight time which is generally tracked on the hobbs meter (positive oil pressure or master switch on depending on configuration). There is a lot of other time in ground school, flight planing, pre-flight checks, and waiting for weather to pass that you will undoubtedly run into. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Looks like &lt;a href=&quot;http://www.langleyflyingschool.com/Pages/Licencing%20Requirements.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Canada requires 45 hours&lt;/a&gt; and thats day only. The &lt;a href=&quot;https://en.wikipedia.org/wiki/Pilot_licensing_in_the_United_Kingdom&quot; rel=&quot;nofollow noreferrer&quot;&gt;UK also requires 45 hours&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These hours are for &lt;a href=&quot;https://en.wikipedia.org/wiki/Visual_flight_rules&quot; rel=&quot;nofollow noreferrer&quot;&gt;VFR only&lt;/a&gt;. An instrument rating, which is not a separate license but an additional rating on the pilot certificate, will take more hours. Some countries limit night flying privileges without an instrument rating, and if you intend on doing any serious flying its a good idea to have.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned by &lt;a href=&quot;https://aviation.stackexchange.com/users/12623/ron-beyer&quot;&gt;Ron&lt;/a&gt; in the comments, not all licenses are valid everywhere. Some are recognized with limitations, and some can be transferred depending on what you are trying to do. Some privileges may be recognized if you are flying to an area to visit etc. Other situations may require more training or filing different types of flight plans. Almost everyone is on ICAO format these days.    &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-05-24T17:13:13.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27769" PostTypeId="2" ParentId="27741" CreationDate="2016-05-24T18:28:01.250" Score="3" Body="&lt;p&gt;@zach-lipton has a pretty concise answer about airports. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the SFO class B airspace, the training area is primarily NE (Calaveras) to SE (&quot;UTC&quot; / Anderson Lake) of KRHV (and South to East of KLVK). If you're departing from KPAO, it's a good 15-20 mins each way to and from the training area. KPAO also has IMC more frequently than KRHV, which is a big advantage if you're mostly going to fly VFR. It's also further out to get to non-towered airports from KPAO (E16/KTCY/C83 are the closest). Highway 101 N/S is pretty busy around KPAO (Embarcadero exit), so unless you will generally avoid the morning/evening commute, KRHV may be easier to get to by road than KPAO.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;KSJC is a busy airport, but they do accommodate GA training operations if they can. I would recommend against using KSJC GA as your transit point though -- KRHV is about 5 miles away, and much cheaper.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're a visiting pilot and want to use the transient parking, transient tiedown fees apply -- see &lt;a href=&quot;http://www.cityofpaloalto.org/civicax/filebank/documents/46915&quot; rel=&quot;nofollow&quot;&gt;KPAO&lt;/a&gt;, &lt;a href=&quot;http://www.countyairports.org/docs/Fees/FeeSchedule_2016.pdf&quot; rel=&quot;nofollow&quot;&gt;KRHV&lt;/a&gt;. Some FBOs or flight schools may offer lower tiedowns in their ramp areas at the airports.&lt;/p&gt;&#xA;" OwnerUserId="15098" LastActivityDate="2016-05-24T18:28:01.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27770" PostTypeId="1" CreationDate="2016-05-24T18:39:39.783" Score="3" ViewCount="2127" Body="&lt;p&gt;I have an &lt;a href=&quot;https://www.flightschoolcandidates.gov&quot; rel=&quot;nofollow&quot;&gt;AFSP (TSA)&lt;/a&gt; approval to train with a part 61 provider. I want to transfer from them to an individual part 61 CFI. Do I need to go through the AFSP approval process again?&lt;/p&gt;&#xA;" OwnerUserId="15099" LastEditorUserId="62" LastEditDate="2016-05-26T15:59:20.110" LastActivityDate="2019-11-19T20:35:00.530" Title="Do I need to get a new AFSP approval if I change to a new part 61 instructor?" Tags="&lt;flight-training&gt;&lt;general-aviation&gt;&lt;usa&gt;&lt;tsa&gt;" AnswerCount="4" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27771" PostTypeId="2" ParentId="27770" CreationDate="2016-05-24T19:17:51.920" Score="5" Body="&lt;p&gt;&lt;strong&gt;Yes&lt;/strong&gt;, you will need to apply for AFSP approval for your new training provider. The &lt;a href=&quot;https://www.flightschoolcandidates.gov/afsp2/common_servlet/help.html?clean=1&amp;amp;nav=guide&quot; rel=&quot;nofollow&quot;&gt;Application Guide&lt;/a&gt; for the AFSP says in step 7:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It is possible for a Candidate to have several active training requests at a given time. These requests may be for the same or different flight training providers. Each training request form will be processed separately; AFSP approval is valid only for the Provider listed in the application.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So if you needed AFSP approval for your original training provider, you will need a new approval to switch to a different provider.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="1696" LastEditDate="2016-05-26T17:08:49.423" LastActivityDate="2016-05-26T17:08:49.423" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27772" PostTypeId="2" ParentId="27393" CreationDate="2016-05-24T20:14:06.877" Score="2" Body="&lt;p&gt;At smaller airports with multiple runways, it is fairly common to get a runway crossing clearance behind an aircraft taking off (or landing). Sometimes the tower will ask you to cross &quot;no delay&quot; if there's another aircraft on short final so you don't get in the way of the arriving aircraft.&lt;/p&gt;&#xA;" OwnerUserId="15098" LastActivityDate="2016-05-24T20:14:06.877" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27773" PostTypeId="2" ParentId="8795" CreationDate="2016-05-24T20:23:47.040" Score="2" Body="&lt;p&gt;The airspace in which the mentioned incident took place is not classified B. In fact, no class B airspace exists in Denmark or Sweden at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The incident did take place in København TMA (which is airspace class C).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So I would like to know which controller normally gives the clearance to enter class B airspace to a VFR flight?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I don't know how this works in the USA, but in most of the world, it is very easy to figure out which ATC unit is responsible for a specific airspace. All aerodrome specific airspaces, such as control zones, are listed in the appropriate AD 2 section of the AIP. For all other airspaces, including TMA's, you should look at the ENR 2.1 section of the AIP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you look up the airspace in question in AIP Denmark, you will see that the responsible ATC unit is Copenhagen APP, specifically the approach east sector (118.450 MHz). So, the &lt;strong&gt;specific&lt;/strong&gt; unit who will give clearances to enter this &lt;strong&gt;specific airspace&lt;/strong&gt; is Copenhagen Approach. There is no &lt;strong&gt;general&lt;/strong&gt; answer to your question, since different procedures are used in different places.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;When entering from class E, does the area controller provide the clearance or the approach controller of the airport whose class B it is?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There is no class E airspace to be found around the position of the incident. Plenty of G, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The ATC unit responsible for providing service in a certain airspace is the only unit who can give a clearance to enter such airspace. In the specific case, Copenhagen Approach is (naturally) the only unit which can issue a clearance into its airspace. If such a clearance is received by another ATS unit, it has been initially provided by Copenhagen Approach and then forwarded to another unit to pass on to the pilot.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;And when the aircraft then crosses from one class B airspace to another?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Again, I think you are assuming that every part of the world works like the USA, which is not the case. What I think you mean is: &lt;em&gt;What happens when an aircraft crosses from one TMA to another?&lt;/em&gt; And what you really should be asking is: &lt;em&gt;What happens when an aircraft crosses from one ATC unit area of responsibility to another?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer to which is quite simple: the aircraft will be transferred to the next ATC unit, who will then provide appropriate service within its airspace.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So does it make any sense it was (still) talking to Swedish controller (the article is not absolutely clear, but seems to say it was Sweden area, not Malmo approach) while the other flight was talking to Kobenhavn approach?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;København TMA - airspace class C - extends from various lower levels to FL195. At the position of the incident, as you have indicated on the chart, the TMA extends from 2500 FT upwards. While Copenhagen Approach provides service within København TMA, service in the airspace below the TMA (which is classified G) is not provided by Copenhagen Approach. Unlike other Danish airports, where the local approach unit will provide service &quot;in, above, below and around&quot; the TMA, Copenhagen Approach is simply too busy dealing with IFR traffic to and from EKCH. Service to traffic below the TMA (which is mainly VFR traffic) is thus provided partly by Malmö ACC (Sweden Control), partly by Copenhagen FIS (Copenhagen Information).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As it so happens, service within Malmö TMA (which is class C, rather than class B as you suggest) is also provided by Sweden Control. There is no approach unit at ESMS - approach control service is provided by Malmö ACC. Therefore, it makes perfect sense that the pilot, coming from the east, was talking to Sweden Control. And since the controllers on the Sweden Control sector had no reason to assume otherwise, they had to believe that the VFR flight in question was in fact below København TMA, in class G airspace, where Copenhagen Approach does &lt;em&gt;not&lt;/em&gt; provide service. This is of course not true - the VFR flight was actually in København TMA, for reasons which are beyond the scope of this to discuss - and as such, should have been talking to Copenhagen Approach (and should have been operating a mode C transponder).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the same time, the IFR arrival (737) was approaching EKCH, within København TMA (class C), and so, was correctly talking to Copenhagen Approach.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What happened then can be read from the incident report. My purpose with this was simply to clear up the misunderstanding concering the airspace in question (which is also what the original question was about).&lt;/p&gt;&#xA;" OwnerUserId="14957" LastEditorUserId="524" LastEditDate="2016-05-24T21:43:37.040" LastActivityDate="2016-05-24T21:43:37.040" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27775" PostTypeId="2" ParentId="19231" CreationDate="2016-05-24T22:54:23.517" Score="1" Body="&lt;p&gt;Direct law:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the data for the C* law is no longer valid, or upon landing gear extension when the alternate law is active, the direct law is activated in pitch. The side stick directly controls the elevator position. Therefore the side stick position is no longer generates a load factor demand as a function of the position of the side stick and inertial feedbacks.&#xA;The THS is mechanically controlled and no flight envelope protections are included.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In lateral control, the side stick movements directly control the position of the ailerons and the spoiler 4 and 5.&lt;/p&gt;&#xA;" OwnerUserId="15062" LastEditorUserId="15062" LastEditDate="2016-05-26T23:13:09.853" LastActivityDate="2016-05-26T23:13:09.853" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27776" PostTypeId="1" AcceptedAnswerId="27778" CreationDate="2016-05-24T23:45:35.220" Score="5" ViewCount="282" Body="&lt;p&gt;I'm a student who is curious about designing his own pulse jet engine, I am wondering if there are any schematics designs, notes, and other related materials I could/should study to learn about these engines. Where can I find such things and what is a good place to start?&lt;/p&gt;&#xA;" OwnerUserId="15103" LastEditorUserId="1696" LastEditDate="2016-07-05T19:31:36.057" LastActivityDate="2016-07-05T19:31:36.057" Title="What is a good place to start learning about pulse jets?" Tags="&lt;jet-engine&gt;&lt;engine-design&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27777" PostTypeId="2" ParentId="27770" CreationDate="2016-05-24T23:48:16.060" Score="2" Body="&lt;p&gt;Yes you do.  I've had two Germans and an Indian receive training from me while here on visas.  I was freelance, and they all had to go through ASFP.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There must be a new training request submitted each time a student in this situation changes training providers, and yes, I had to register with flightschoolcandidates.gov as a flight training provider and was involved with the students' application processes.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-26T17:26:04.860" LastActivityDate="2016-05-26T17:26:04.860" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27778" PostTypeId="2" ParentId="27776" CreationDate="2016-05-25T02:32:33.263" Score="4" Body="&lt;p&gt;You could try &lt;a href=&quot;http://www.pulse-jets.com/&quot; rel=&quot;nofollow&quot;&gt;this website on home made pulse jets&lt;/a&gt; looks like it has some good info. &lt;a href=&quot;http://www.pulsejetengines.com/&quot; rel=&quot;nofollow&quot;&gt;These guys are selling some plans&lt;/a&gt; and have info as well. Here is an &lt;a href=&quot;http://www.instructables.com/id/Make-a-Pulse-jet-engine-Scanned-from-1958-plans/&quot; rel=&quot;nofollow&quot;&gt;interesting instructables&lt;/a&gt;... And here is &lt;a href=&quot;http://www.colinfurze.com/big-pulse-jet-project.html&quot; rel=&quot;nofollow&quot;&gt;another DIY one&lt;/a&gt;. You may also be able to dig up some of the work that was done with them during WWII with a bit of directed searching on some public archives (as it may be more or less public record now). Of course physics and engineering text books will always be of help but there may not be any pulse jet specific ones. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PSA: You should take extreme caution when building and testing something like this. You will presumably be burning jet fuel (or another comburent) in a home made combustion chamber which can lead to very bad things. Care should always be taken when firing up an engine (of any kinda) for the first time. Welds should be double checked, metal choice is important and please wear safety goggles!   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="1467" LastEditDate="2016-05-25T13:37:13.010" LastActivityDate="2016-05-25T13:37:13.010" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27779" PostTypeId="2" ParentId="27763" CreationDate="2016-05-25T03:43:58.760" Score="12" Body="&lt;p&gt;I am not sure about all aircraft types, but on the 777 cabin pressure is still used to positively lock the door into position in flight. When the door is open, the door is in a slightly raised position. As the door is closed, rollers on the door are lowered into tracks on the door frame. The tracks are curved slightly outwards, so to open the door the it most be moved slightly inward, which is impossible even with a slight amount of cabin pressure. The actual pressure load on the door is carried through the stops, which are inboard on the door and outboard on the frame. Once loaded with the pressure, these stops would also have a tremendous amount of friction preventing the door from sliding upward. Note the vent door near the top of the door in the picture below, this door is attached to the latching mechanism and it opens in the first movement of the handle, again preventing the door from unlatching if the cabin is pressurized.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Refer to this picture of the 777 door, to see the rollers, tracks and stops (&lt;a href=&quot;http://www.airliners.net/photo/Malaysia-Airlines/Boeing-777-2H6-ER/1731209/L/&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/uTZDQ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/uTZDQ.jpg&quot; alt=&quot;777 Door Frame&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I believe the 777 design is very similar to the Airbus design. There is a very good video showing the operation of Airbus doors on YouTube, &lt;a href=&quot;https://www.youtube.com/watch?v=oqOyLKZApuc&quot; rel=&quot;noreferrer&quot;&gt;here&lt;/a&gt;. It shows how the door must be lifted above the stops, before it can open outward. If you watch closely you can see the move slight inboard before lifting. This is a quote from the A340 maintenance manual: The lifting arms of the lifting shaft (which support the passenger door in roller fittings attached to the door frame) move the passenger door a small distance into the cabin and then upwards.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note, some people (including Airbus and Boeing) still consider these doors plug designs since pressure still loads the door against the stops. For example, Boeing specifically states the 777 doors are plug type doors.&lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="13366" LastEditDate="2016-06-09T03:59:02.617" LastActivityDate="2016-06-09T03:59:02.617" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27780" PostTypeId="1" CreationDate="2016-05-25T04:48:17.293" Score="5" ViewCount="5103" Body="&lt;p&gt;I was reading the Cessna 150H POH earlier today and noticed that the manual mentions something like &quot;Normal cruising is done at 65% to 75% of METO power.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Cessna 172S POH charts refer to cruising power as &quot;75% MCP.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that METO stands for &quot;Maximum Except for Take Off&quot; and MCP stands for &quot;Maximum Cruising Power&quot;, are the two terms the same thing or do they have differences?&lt;/p&gt;&#xA;" OwnerUserId="15104" LastEditorUserId="1467" LastEditDate="2016-05-25T06:38:58.677" LastActivityDate="2020-01-11T00:41:30.620" Title="What is the difference between MCP and METO?" Tags="&lt;terminology&gt;&lt;cessna-172&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27781" PostTypeId="2" ParentId="15519" CreationDate="2016-05-25T05:05:41.087" Score="3" Body="&lt;p&gt;Such information is not available, for free, on a world wide level.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are willing to spend some money, you should have a look at &lt;a href=&quot;https://www.navigraph.com/&quot; rel=&quot;nofollow&quot;&gt;Navigraph&lt;/a&gt;, which provides such information on a world wide level, for hobby use.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, most countries now make their AIP publically available on the internet. Simply search for &quot;[country name] AIP&quot; to look up an AIP for a specific country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any AIP, you want to look at part 3 of the ENR section. Usually ENR 3.1, ENR 3.2 or ENR 3.3. Here is an example of from AIP Denmark: &lt;a href=&quot;http://aim.naviair.dk/AIM%20Documents/AIP%20Danmark/AIP%20PART%202%20-%20EN%20ROUTE%20%28ENR%29/ENR%203%20ATS_RNAV%20ROUTES/EK_ENR_3_3_en.pdf&quot; rel=&quot;nofollow&quot;&gt;AIP Denmark ENR 3.3 - RNAV routes&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This information is digital, official, up to date, free and in WGS84 format. However, you will have to look it up for every country.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking for a visual overview of airways and RNAV routes in Europe, a good place to start is the &lt;a href=&quot;http://www.eurocontrol.int/articles/eurocontrol-regional-charts-erc&quot; rel=&quot;nofollow&quot;&gt;Eurocontrol regional charts&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should also check out &lt;a href=&quot;https://skyvector.com/&quot; rel=&quot;nofollow&quot;&gt;SkyVector&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-05-25T05:05:41.087" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27784" PostTypeId="2" ParentId="25396" CreationDate="2016-05-25T08:48:11.593" Score="-2" Body="&lt;p&gt;Technically possible but not very comfortable. As a first step, windowless passenger aircraft could be attempted. In crowded Indian buses with windows being swamped by opaque advertising material it is very disconcerting not knowing where you have reached. Passenger experiences can be taken as a starting point. Also the experience of astronauts could be considered....&lt;/p&gt;&#xA;" OwnerUserId="15106" LastActivityDate="2016-05-25T08:48:11.593" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27785" PostTypeId="1" AcceptedAnswerId="29584" CreationDate="2016-05-25T09:54:59.427" Score="3" ViewCount="2412" Body="&lt;p&gt;I understand higher speed, and higher drag mean higher adiabatic compression leading to heating up the air, and the plane as result. &lt;a href=&quot;https://en.wikipedia.org/wiki/North_American_X-15&quot; rel=&quot;nofollow noreferrer&quot;&gt;X-15&lt;/a&gt; needed ablative coating to prevent overheating. On reentry of space vehicles heat shielding is the most critical problem. This is perfectly understandable as higher speed with constant or growing air density means higher drag - and this results in higher speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd like to know &lt;em&gt;how&lt;/em&gt; are these values related though. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;[for the purpose of this question, let's neglect the issues of engine efficiency. We have a magical rocket engine that weighs nothing and needs no air nor fuel to produce thrust. This is a purely an aerodynamics question.]&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At given pressure, drag is directly proportional to lift (both being &lt;a href=&quot;https://engineering.stackexchange.com/questions/3018/how-is-lift-related-to-airspeed&quot;&gt;quadratically&lt;/a&gt; proportional to airspeed and linearly to air density). That means higher airspeed allows raising the altitude, lowering air density, and thus lowering drag until lift and gravity even out.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's maintain such a flight: We're constantly accelerating (slowly); and climbing, at such a rate, that lift remains constant, and evens out with gravity (minus a minimal delta to retain climb). The increase of lift coming from rising airspeed is being offset by decreasing air density as the craft climbs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With constant lift, and drag being directly proportional to lift, drag remains constant too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maintaining constant drag through climb like that, air density is inversely proportional to square of airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How would heat creation behave in this situation though?&lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="-1" LastEditDate="2017-04-13T12:51:48.340" LastActivityDate="2016-06-27T19:13:38.727" Title="What is the relation between airspeed and generated heat at constant drag?" Tags="&lt;aerodynamics&gt;" AnswerCount="2" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27786" PostTypeId="5" CreationDate="2016-05-25T10:40:18.113" Score="0" Body="" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-05-25T10:40:18.113" LastActivityDate="2016-05-25T10:40:18.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27787" PostTypeId="4" CreationDate="2016-05-25T10:40:18.113" Score="0" Body="A lighter-than-air aircraft without its own means of propulsion, typically filled with helium, hydrogen, or hot air." OwnerUserId="1467" LastEditorUserId="22726" LastEditDate="2019-02-21T16:09:09.267" LastActivityDate="2019-02-21T16:09:09.267" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27788" PostTypeId="2" ParentId="9931" CreationDate="2016-05-25T11:25:59.210" Score="5" Body="&lt;p&gt;High altitude balloons going into commercial airspace that are large enough to be a threat to a plane require a NOTAM to be issued and even small balloon launches are encouraged to have a NOTAM. Also, a weather balloon will not spend very much time in the danger zone but will drift right through it, so the exposure is brief. Most commercial fights occur along well-known corridors and flight paths. Balloons are often launched far away from those lines of travel. Just that alone makes it pretty safe. Small planes do the same thing: stay away from commercial flight corridors.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-25T11:25:59.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27789" PostTypeId="1" AcceptedAnswerId="27791" CreationDate="2016-05-25T13:06:46.870" Score="6" ViewCount="3233" Body="&lt;p&gt;I was on the flight CX635 from Hong Kong to Singapore today, and I noticed the plane turning in a circle reminiscent of the holding pattern that planes often enter when they are queuing up to land. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, this time I saw this flight pattern on the in-flight tracker while it was still in level flight, and once again when it was descending. When I got home, I saw that the pattern was also recorded on &lt;a href=&quot;https://www.flightradar24.com/data/flights/cx635/#9d14c73&quot; rel=&quot;noreferrer&quot;&gt;FlightRadar24&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/m9c1e.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/m9c1e.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why did the pilot fly two circles in the middle of the ocean off the east coast of West Malaysia? I did not observe any obvious severe weather patterns, and the clouds were generally sparse (2 oktas or so) when it was doing the first roundabout, and there were no visible indicators of significant severe weather activity. &lt;/p&gt;&#xA;" OwnerUserId="5537" LastActivityDate="2016-05-25T13:43:25.133" Title="Why did this commercial flight fly in circles while far from the destination?" Tags="&lt;flight-planning&gt;&lt;flight-path&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="2" ClosedDate="2016-05-25T21:15:35.107" ContentLicense="CC BY-SA 3.0" />
  <row Id="27790" PostTypeId="1" CreationDate="2016-05-25T13:07:45.967" Score="2" ViewCount="567" Body="&lt;p&gt;The answer to the question about &lt;a href=&quot;https://aviation.stackexchange.com/questions/1640/what-is-the-difference-between-oat-rat-tat-and-sat/1642#1642&quot;&gt;OAT, RAT, TAT, and SAT&lt;/a&gt; has the following:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Problem is, not all instruments will compress that air in the same way, and not all of them will pick up this Ram Rise entirely. So they will publish a K, a ram-rise-coefficient (also called recovery factor) meaning how much of from the theoretical Ram Rise they actually pick up.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It appears for speeds exceeding 1.5 Mach, Ram Rise starts achieving oppressive values. At 1.6 Mach, and -25C SAT we're already dealing with temperature rise to above 100C. The only &quot;redeeming factor&quot; is K, which may prevent such rapid and drastic rise for a short while.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What orders of magnitude does &lt;em&gt;K&lt;/em&gt; appear in, in typical scenarios where ram rise starts playing a role - a supersonic fighter, a missile, a rocket? &lt;/p&gt;&#xA;" OwnerUserId="12341" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-25T13:07:45.967" Title="What orders of Ram Rise Coefficient (Recovery Factor) are commonly encountered?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;aircraft-physics&gt;" AnswerCount="0" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27791" PostTypeId="2" ParentId="27789" CreationDate="2016-05-25T13:22:07.093" Score="14" Body="&lt;p&gt;The first &quot;circle&quot; is a holding pattern. We discussed those &lt;a href=&quot;https://aviation.stackexchange.com/q/12481/1467&quot;&gt;here&lt;/a&gt;.&#xA;In particular, it seems that you were on hold at VINIL or VEPLI, according to the &lt;a href=&quot;http://www.fly-sea.com/charts/WSSS.pdf&quot;&gt;approach charts&lt;/a&gt; (page 5 of the PDF).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second one is most likely for separation on final approach, the aircraft was probably early and ATC has asked them to perform a 360° to increase the separation between them and the aircraft in front.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-05-25T13:43:25.133" LastActivityDate="2016-05-25T13:43:25.133" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27795" PostTypeId="2" ParentId="9931" CreationDate="2016-05-25T16:41:41.017" Score="7" Body="&lt;p&gt;High altitude balloons reach more like 30km rather than kft. This means that there's a limited time in which they can interfere with normal aviation traffic (which, during cruise, is usually in a fairly narrow band between 8-12km).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Outside of cruise can be more of a problem (i,e: When landing or taking-off). For that reason it's essential to launch from somewhere far from an airport, so that the balloon can ascend in a location where it will not affect air traffic. Most countries also require you to inform air traffic control in advance of a balloon launch so that they can issue a warning (NOTAM) to pilots that lets them know to be aware of balloon activity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, one can reduce the risk to aviation by constructing the balloon payload carefully. The balloon itself doesn't pose much of a risk but a heavy/dense payload can. To reduce the risk lightweight components should be used and dense items like batteries kept to a minimum. Most countries also have rules governing the size and weight of the balloon that you can launch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For balloons that can't meet the rules (too heavy, need to launch near an airport, etc) there's two choice: &#xA;1) Don't launch.&#xA;2) Perform a much more extensive risk analysis and actively divert air traffic away from the balloon. This requires air traffic control to be able to see the balloon (using a radar reflector or, more usually, a transponder). Because of the cost of this option it's normally only very important or high-value payloads that are sent this way (such as NASA's research balloons).&lt;/p&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-05-25T16:41:41.017" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27796" PostTypeId="1" CreationDate="2016-05-25T17:14:23.193" Score="4" ViewCount="771" Body="&lt;p&gt;What is the difference between dry operating mass and dry operating weight in the context of rotorcraft?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the formula for converting mass to weight?&lt;/p&gt;&#xA;" OwnerUserId="15110" LastEditorUserId="3201" LastEditDate="2016-05-26T10:54:59.060" LastActivityDate="2016-05-26T11:28:52.717" Title="What is the difference between dry operating weight and dry operating mass?" Tags="&lt;helicopter&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27797" PostTypeId="1" AcceptedAnswerId="27798" CreationDate="2016-05-25T18:08:00.453" Score="15" ViewCount="3056" Body="&lt;p&gt;I have never reported reckless behavior by other pilots to the FAA, but I have thought about it several times. The only problem is that usually I will only know the tail number, not the name of the pilot. Since the owner of the aircraft may be different than the one flying it, how does one go about making sure the complaint is filed against the right person?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2018-03-11T20:09:05.733" Title="How do you report reckless pilots?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;faa&gt;&lt;aircraft-registration&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27798" PostTypeId="2" ParentId="27797" CreationDate="2016-05-25T18:36:50.893" Score="16" Body="&lt;p&gt;The FAA provides an &lt;a href=&quot;https://www.faa.gov/contact/safety_hotline/&quot;&gt;online reporting tool here&lt;/a&gt; I would say it falls under &quot;aviation concern&quot;. In your description if you include tail number and time they should be able to figure out who was flying (or in the cockpit if its a 2 man situation). You can also contact your &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot;&gt;local FSDO&lt;/a&gt; and report the tail number and time of incident. Aircraft owners/renters (the people the tail number will trace back to) will more than likely know who was flying a given tail number at a certain time so as long as you know when it happened you should be ok its not necessarily on you to know who was flying but the tail number and incident time is key. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-25T18:36:50.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27799" PostTypeId="2" ParentId="27796" CreationDate="2016-05-25T19:30:21.120" Score="4" Body="&lt;p&gt;Weight is a force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mass is a property of matter. Acceleration makes mass produce a force. Specifically, a mass in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Gravitational_acceleration&quot; rel=&quot;nofollow&quot;&gt;gravitational field of Earth&lt;/a&gt; effects a weight force on its support. The relation between both is the gravitational acceleration g, which is standardized to 9.80665 m/s² (approximately 32.174 ft/s²), as in Weight = Mass · g.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-05-25T19:30:21.120" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27800" PostTypeId="2" ParentId="27776" CreationDate="2016-05-25T19:40:05.717" Score="1" Body="&lt;p&gt;If you look for performance data on the As-014 pulse jet, NACA did some thorough testing of it in 1945. The resulting report E5J02 can be found &lt;a href=&quot;http://naca.central.cranfield.ac.uk/reports/1945/naca-wr-e-269.pdf&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;. It contains information about thrust, fuel flow, pressures and information about the test setup and procedure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;http://www.airbase.ru/modelling/rockets/res/konstr/argus/argus_2.html&quot; rel=&quot;nofollow&quot;&gt;Russian site&lt;/a&gt; has lots of drawings and detail pictures.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-25T19:48:41.113" LastActivityDate="2016-05-25T19:48:41.113" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27801" PostTypeId="2" ParentId="27796" CreationDate="2016-05-25T21:13:29.927" Score="0" Body="&lt;p&gt;Weight = Mass x Gravity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In typical aviation terms, in an operational sense, you don't need to worry about mass (unless you're talking about a spacecraft...)&lt;/p&gt;&#xA;" OwnerUserId="3746" LastActivityDate="2016-05-25T21:13:29.927" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27802" PostTypeId="1" AcceptedAnswerId="27811" CreationDate="2016-05-25T21:30:47.413" Score="21" ViewCount="3524" Body="&lt;p&gt;Commercial airlines spend a lot of their operating income on fuel, so in order to maximize shareholder value presumably like to use as little fuel as is safely possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are commercial pilots ever given incentives (e.g. financial, performance review) for reducing fuel usage, or given dis-incentives for excessive fuel usage?&lt;/p&gt;&#xA;" OwnerUserId="2797" LastActivityDate="2019-03-13T14:35:51.783" Title="Are commercial pilots incentivized to reduce fuel consumption?" Tags="&lt;commercial-aviation&gt;&lt;fuel&gt;" AnswerCount="4" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27803" PostTypeId="1" AcceptedAnswerId="27807" CreationDate="2016-05-25T21:35:31.550" Score="4" ViewCount="1101" Body="&lt;p&gt;I'd like to understand what electrical power sources are available (engines? APU? GPU? Other?) on a larger jet like the G550, and how much power they can provide, depending on whether the airplane is flying at cruise speed or on the ground. I'm curious about how much electrical load can be added to the aircraft and how.&lt;/p&gt;&#xA;" OwnerUserId="15113" LastEditorUserId="19" LastEditDate="2016-05-25T23:16:50.453" LastActivityDate="2016-05-26T12:14:39.640" Title="How much electrical power is available in a Gulfstream G550 and from which power sources?" Tags="&lt;jet-engine&gt;&lt;aircraft-systems&gt;&lt;jet&gt;&lt;electrical-system&gt;&lt;apu&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27806" PostTypeId="1" AcceptedAnswerId="27816" CreationDate="2016-05-26T02:01:04.163" Score="6" ViewCount="772" Body="&lt;p&gt;I was looking at the predicted flight path for &lt;a href=&quot;http://flightaware.com/live/flight/UAL106/history/20160525/2140Z/KIAD/EDDM&quot; rel=&quot;nofollow noreferrer&quot;&gt;UA106 from IAD to MUC&lt;/a&gt; and noticed this odd pattern. Why would it do this? I understand that most flight paths are not straight and there are &lt;a href=&quot;https://aviation.stackexchange.com/questions/11506/why-do-pilots-use-airways-instead-of-just-flying-direct-every-time&quot;&gt;airways that most all flights follow&lt;/a&gt;, but this path makes two less than 90 degree turns. Wouldn't it be simpler to go straight to the Belgium point rather than go to Poland, then back to Belgium, then back again to Munich?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/02Q4H.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/02Q4H.png&quot; alt=&quot;flight path&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="15116" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.873" LastActivityDate="2020-09-23T11:41:07.070" Title="Why has flight UA106 such a strange predicted flight path?" Tags="&lt;flight-path&gt;" AnswerCount="1" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27807" PostTypeId="2" ParentId="27803" CreationDate="2016-05-26T02:20:02.037" Score="3" Body="&lt;p&gt;There are some answers to &lt;a href=&quot;http://www.gulfstreamcontractpilotservices.com/resources/gulfstream-library/gv-systems-1-electrical.php&quot; rel=&quot;nofollow&quot;&gt;common electrical questions about the G550 here&lt;/a&gt; according to them the engine integrated drive generator (IDG) unit delivers 40KVA, 400HZ, 115V; they don't list a &lt;a href=&quot;http://www.coresite.com/resources/thought-leadership/faq-what-is-kva&quot; rel=&quot;nofollow&quot;&gt;power factor but lets be conservative and assume .8 (it must be between 0 and 1)&lt;/a&gt;. This would result in 32 Kilowatts per IDG. So you have 64 Kilowatts at your disposal. The minimum load will depends on the avionics installed and can vary from plane to plane. At night load will be increased as a result of the use of interior lights as well as landing lights during takeoff and approach. Your load will be highly variant on the interior of the aircraft. As this is a luxury plane there could be a whole host of things inside like TV's, lights, kitchen equipment etc. You can find specific equipment installations in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Aircraft_flight_manual&quot; rel=&quot;nofollow&quot;&gt;POH/loading info&lt;/a&gt; for a given airframe. You can find a nice breakdown of the &lt;a href=&quot;http://code7700.com/g450_electrical_ac_sources.html&quot; rel=&quot;nofollow&quot;&gt;G450's electrical system here&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how you can add it, you can simply add it as you would add any accessory, to the main bus (by an A&amp;amp;P of course). You will need to make sure the item can be added to the craft and in some cases there may be a stipulation along the lines of not using it during takeoff or landing. The amount of load will vary by aircraft and dependent on what else is installed.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I'd like to understand what electrical power sources are available&#xA;  (engines? APU? GPU? Other?)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The engines (while running) are generally the main source of power. The APU is often used on the ground when the engines are off but the plane needs electronics on and can also serve to help start the engines. It &lt;a href=&quot;http://www.gulfstreamcontractpilotservices.com/resources/gulfstream-library/gv-training-2-apu-starting.php&quot; rel=&quot;nofollow&quot;&gt;does appear the G550 has an APU&lt;/a&gt;. According to &lt;a href=&quot;http://investor.honeywell.com/Cache/1500080545.PDF?O=PDF&amp;amp;T=&amp;amp;Y=&amp;amp;D=&amp;amp;FID=1500080545&amp;amp;iid=4121346&quot; rel=&quot;nofollow&quot;&gt;this data sheet&lt;/a&gt; the G550 runs a &lt;a href=&quot;https://aerospace.honeywell.com/en/products/auxiliary-power-and-thermal/re220-apu&quot; rel=&quot;nofollow&quot;&gt;Honeywell RE220 APU&lt;/a&gt; that can output 45 Kilowatts. According to the site it will operate up to 37,000+ Ft. so it in theory could be run for the duration of a flight. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Shorepower#Aircraft&quot; rel=&quot;nofollow&quot;&gt;GPU is only available on the ground&lt;/a&gt; and only at airports that have them. Their output varies widely and a large variety of types may be available at any given airport. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2016-05-26T12:14:39.640" LastActivityDate="2016-05-26T12:14:39.640" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27808" PostTypeId="2" ParentId="14379" CreationDate="2016-05-26T02:30:55.747" Score="6" Body="&lt;p&gt;What is great about google earth flight sim is what makes it unrealistic. I can experience things I would never have the opportunity to experience: like diving down the face of Everest at full throttle, Landing at the bottom of the Marianas Trench, skimming just beneath the surface of the water as we approach LA at 1200 knots, and landing on Hadley Delta on the Moon. All for free. All safe, and tell  my friends how I like to land at Boston, Heathrow, and a tiny airport in Peru surrounded by mountains.&#xA;The truth is I am terrified of getting on a real plane, but Google Flight simulator's suspension of reality restores the fun of flying, and makes me wonder if I should not be so scared to get on a real plane.&lt;/p&gt;&#xA;" OwnerUserId="15118" LastActivityDate="2016-05-26T02:30:55.747" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27810" PostTypeId="2" ParentId="27802" CreationDate="2016-05-26T03:35:54.120" Score="2" Body="&lt;p&gt;It's seems like you are talking about part 121 operations which is like delta to Chicago and Atlanta and daily passenger operations. The pilots don't really do the weight and balance(fuel required). Dispatchers do the calculations and then it's sent to the pilots and they double check the math. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm gonna say they don't because it's already at mins. &#xA;Then you have other factors like it's cheaper to buy fuel at this airport so I will top of the tanks so you can fly to another airport and back. &lt;/p&gt;&#xA;" OwnerUserId="11761" LastActivityDate="2016-05-26T03:35:54.120" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27811" PostTypeId="2" ParentId="27802" CreationDate="2016-05-26T04:56:23.590" Score="22" Body="&lt;p&gt;There have been, at various times, and with various carriers, incentive programs set up to encourage pilots to save fuel, improve on-time performance, or some combination of the two.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of a fuel-saving incentives program existed at the former Continental Airlines in the early 90s, where pilots would be paid a bonus for using less fuel than planned. The problem was that it wreaked havoc with the schedule itself, as pilots would simply dial back to economy cruise thrust settings, saving fuel but taking noticeably longer to reach their destinations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An example of an actual-vs-scheduled block incentive program intended to help with on-time performance existed at Silver Airways in their Beech 1900D fleet, whereby pilots would be paid a bonus for each minute they were able to shave off a baseline target time. Ironically enough, it was called the &quot;Green Incentive Program&quot; (don't ask). And it was a can of worms.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I vaguely remember other airlines experimenting with incentives programs relating to fuel consumption and on-time performance, but it's been several years since I left the industry and can't recall any other examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In short, yes they do get implemented fairly regularly, but they can be very problematic due to the difficulty in properly designing and managing them (incentivization is a complex problem).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lastly, since another poster has brought this up, dispatchers do indeed perform most, if not all the flight planning, but the PIC (i.e. Captain of the flight) has the option of overriding most everything the dispatcher plans and arranges for (subject to the carrier's Operational Specifications), including amount of fuel to be carried. Basically, if the Captain decides that the plane is to be filled with as much fuel as it can carry up to MTOW, that's what's going to happen. Might not be the most business-savvy (or even prudent) decision, but it's part of their prerogative as PIC (i.e. the person ultimately responsible for the craft, crew, passengers, and goods onboard).&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2016-05-26T04:56:23.590" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27812" PostTypeId="1" AcceptedAnswerId="27817" CreationDate="2016-05-26T05:56:31.093" Score="4" ViewCount="673" Body="&lt;p&gt;For Class B airports, I think the answer is realistically yes, due to traffic flows. How about Class C airports? Are there any legal requirements that it has to operate in 24/7, or is a convention?&lt;/p&gt;&#xA;" OwnerUserId="12019" LastActivityDate="2016-05-26T13:22:40.750" Title="Do all Class B and Class C towers operate 24/7?" Tags="&lt;faa-regulations&gt;&lt;airspace&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27813" PostTypeId="2" ParentId="27796" CreationDate="2016-05-26T11:28:52.717" Score="3" Body="&lt;p&gt;The problem occurs due to lazy terminology. In aviation both normally mean the same thing: The reading you would get if you put the empty aircraft onto a large weighing device (scales, or whatever). This is normally given in kilograms (kg) or pounds (lb).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This trouble arises because both of these quantities are actually masses, the weights would be in Newtons (N) or pounds-force (lbf). To transform the mass into a weight you multiply by the local gravity, g, which is usually assumed to be 9.81m/s2.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar problem exists when at home: If you weigh yourself on standard bathroom scales you will normally see a value in kilograms (i.e: A mass), but the scales actually measure a force. This means if you use the same scales on another planet you will get a different value in kilograms, which is nonsensical. The same goes for aviation: Weight and mass are being used interchangeably, which is incorrect.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;edit - And to specifically answer your question: Dry weight and dry mass mean the same thing in this context.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12234" LastActivityDate="2016-05-26T11:28:52.717" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27816" PostTypeId="2" ParentId="27806" CreationDate="2016-05-26T12:53:09.053" Score="25" Body="&lt;p&gt;As @mins suggested, it seems to be a wrong longitude of a waypoint in the Shannon Control area. I assume it is a hemisphere error (they used East instead of West).&#xA;If the longitude of the waypoint is mirrored with respect to the Greenwich meridian, the resulting path gives a more likely route to be flown:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/t3ypF.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/t3ypF.png&quot; alt=&quot;Corrected path&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="19" LastEditDate="2020-09-23T11:41:07.070" LastActivityDate="2020-09-23T11:41:07.070" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="27817" PostTypeId="2" ParentId="27812" CreationDate="2016-05-26T13:22:40.750" Score="7" Body="&lt;p&gt;The short answer is no. It's easy to find examples of class C towers that aren't 24/7, by checking in the &lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dafd/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Chart Supplement&lt;/a&gt;. Two examples are &lt;a href=&quot;http://airnav.com/airport/KXNA&quot; rel=&quot;nofollow noreferrer&quot;&gt;KXNA&lt;/a&gt; (as &lt;a href=&quot;https://aviation.stackexchange.com/questions/27812/do-all-class-b-and-class-c-towers-operate-24-7#comment68882_27812&quot;&gt;mentioned&lt;/a&gt; in the comments) which operates 1130-0500Z and &lt;a href=&quot;http://airnav.com/airport/KHSV&quot; rel=&quot;nofollow noreferrer&quot;&gt;KHSV&lt;/a&gt;, which operates 1200-0600Z. Note that the airspace changes when the tower is closed: KXNA becomes class G, and KHSV becomes class E.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for class B, I would also assume that they're 24/7. I checked a few (KATL, KBOS, KSEA) in the Chart Supplement and they are indeed 24/7 but I don't feel like checking them all :-)&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-05-26T13:22:40.750" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27819" PostTypeId="2" ParentId="16793" CreationDate="2016-05-26T17:46:50.917" Score="1" Body="&lt;p&gt;There is no guidance as far as I am aware of.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Most good pilots make their own checklists for smaller aircraft. Generally speaking different pilots like different levels of detail and size formats for the checklist. So, you might have one pilot with an 8.5&quot; x 11&quot; monster checklist with a lot of detail and another guy who is using an index card strapped to his forearm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would keep the color and symbology to a minimum. You cannot see color at night. Also, other people may need to use your checklist or may look at it (like a flight examiner). You do not want to have cryptic elements on a checklist that could be misinterpreted.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is an advantage to simplicity.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-26T17:46:50.917" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27820" PostTypeId="2" ParentId="27785" CreationDate="2016-05-26T17:57:29.187" Score="1" Body="&lt;p&gt;A given airplane moving through the atmosphere at at given weight and velocity requires a specific and determinate amount of energy. That known energy can be expressed in foot-pounds, calories, btu's, etc. There are simple, straightforward conversions between these metrics. btu's typically represent heat energy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A simple approach to determine the energy in foot-pounds is to fly at a known HP setting and fly for a specific time frame. The product of that HP times that time represents energy. Simply convert it to btu's. &lt;/p&gt;&#xA;" OwnerUserId="15129" LastActivityDate="2016-05-26T17:57:29.187" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27821" PostTypeId="1" CreationDate="2016-05-26T19:44:45.637" Score="1" ViewCount="132" Body="&lt;p&gt;I'm not entirely sure this is appropriate for this forum but it's worth a shot...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have propeller data ($C_T$ , $C_P$ , J , and $\eta$) and very very limited electric brushless motor data (motor diameter, shaft diameter, Kv, voltage range, max amperage) I am trying to put together a power available curve (P vs V) but I'm not exactly sure how to use the data I have to do so.  How do I get shaft power from my engine data?  Or what can I use?&lt;/p&gt;&#xA;" OwnerUserId="781" LastEditorUserId="34686" LastEditDate="2020-02-29T21:59:49.733" LastActivityDate="2020-05-06T23:06:31.700" Title="How can I use electric motor data with my prop data to obtain a power available versus velocity curve?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;engine&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="27822" PostTypeId="1" CreationDate="2016-05-26T21:08:21.153" Score="4" ViewCount="611" Body="&lt;p&gt;I want to scale down my propeller for a wind tunnel testing. But I am unable to find any literature on it.  Please give suggestions.&lt;/p&gt;&#xA;" OwnerUserId="11167" LastEditorUserId="19" LastEditDate="2016-06-21T16:09:25.443" LastActivityDate="2016-12-30T21:56:25.370" Title="How can I scale down a propeller for wind tunnel testing?" Tags="&lt;propeller&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27823" PostTypeId="1" AcceptedAnswerId="27825" CreationDate="2016-05-26T22:00:02.080" Score="12" ViewCount="14087" Body="&lt;p&gt;This question goes against everything I've read or heard with the exception of a suggestion from my CFI in my last flight lesson, so I was hoping to get some clarification:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During a left turn into our crosswind leg my instructor informed me that I shouldn't be using so much left rudder, and in fact, might even need to use some &lt;em&gt;right&lt;/em&gt; rudder to stay coordinated due to the left turning tendencies of the plane. I could &lt;em&gt;somewhat&lt;/em&gt; understand given that I definitely noticed a tendency for the plane to roll more when turning left than right, but still I would think the antidote for that would just be less left rudder, not opposite rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This does not make sense to me. In what situations would I need to do this? I was still able to perform my turns just fine with slight right rudder on my left turns, but I would like to understand this more.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;FYI - I'm flying a Piper Cherokee 140 (PA-28-140)&lt;/p&gt;&#xA;" OwnerUserId="13937" LastEditorUserId="19" LastEditDate="2016-07-06T08:36:29.860" LastActivityDate="2019-04-11T04:58:30.660" Title="Why is using opposite rudder and aileron necessary in left turn for coordination?" Tags="&lt;flight-controls&gt;&lt;rudder&gt;&lt;ailerons&gt;" AnswerCount="8" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27824" PostTypeId="2" ParentId="27823" CreationDate="2016-05-26T22:57:46.403" Score="10" Body="&lt;p&gt;You should just look at the ball and that will remove all doubt. If the ball is to the left, you use left rudder. It's that simple.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After a while, like a couple hundred hours, you will start to feel when the aircraft is coordinated naturally, but until then just look at the ball. Don't fixate on it, though. Just glance down at some point when you are making your turn.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-05-26T22:57:46.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27825" PostTypeId="2" ParentId="27823" CreationDate="2016-05-26T23:03:55.210" Score="11" Body="&lt;p&gt;First and foremost you should always be looking at the turn coordinator to see what is going on and applying rudder as necessary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In your specific case (if we want to discuss the physics), basically what your instructor is saying is that you are using the ailerons to bank (turn) the plane and the rudder to counteract the propeller's yawing moment. The rudder is simply counteracting the Adverse Yaw: the inputs will change depending on how steeply you are banking. If opposite rudder is called for on your ball, then step on it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Perhaps more importantly, what your instructor is actually stressing is during your crosswind, base and final turns you should really be paying attention to staying coordinated. A great deal of Stall -&gt; Spin -&gt; Crashes happen in the pattern as planes slow down and dirty up, thus it's extremely important in the pattern to watch your speed and your turn coordination. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2019-04-11T04:58:30.660" LastActivityDate="2019-04-11T04:58:30.660" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27826" PostTypeId="2" ParentId="27434" CreationDate="2016-05-26T23:30:35.723" Score="2" Body="&lt;p&gt;so after having done some more research this is what I have found.The A320 has two independent gross weight calculations. When the aircraft is on the ground the FMS does the GW calculation. Prior to engine start, the current GW and CG are not defined.; predictions are computed based on the pilot entered ZFW , ZFWCG, blockfuel and the FM calculates the TOW. The GW is calculated  by adding FOB to the pilot entered ZFW (GW=ZFW+FOB)  However I don't know what this iteration rate would be.&#xA;When the A320 is airborne, the FACs independently determine the aircraft gross weight (GW) by using the aircraft angle of attack sensors. If a significant difference occurs between the FAC and FMS gross weighs (delta &gt; 7 tons) , the  message &quot;CHECK GW&quot; will be displayed on the scratchpad. &lt;/p&gt;&#xA;" OwnerUserId="15062" LastActivityDate="2016-05-26T23:30:35.723" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27827" PostTypeId="2" ParentId="27823" CreationDate="2016-05-27T00:31:47.500" Score="0" Body="&lt;p&gt;I agree that this sounds counterintuitive, and my gut tells me that there is some misunderstanding here. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Torque and p-factor will have a greater effect at the lower speed in the traffic pattern.  If, in level flight, you are holding right rudder, then maybe when you're rolling left all you need is a reduction of right and not necessarily input of left in order to maintain coordination.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have very strong doubts that what your instructor is telling you is that you should add right rudder, in the sense of increase it, as you roll left.  If anything it is a decrease of right rudder.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, a reduction of right rudder during the roll is still right rudder in the same way that turning a car's wheels toward center, but still being in a right turn is not considered turning your car left.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-05-27T00:31:47.500" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27829" PostTypeId="2" ParentId="27823" CreationDate="2016-05-27T01:09:55.420" Score="4" Body="&lt;p&gt;The other answers have good general discussions of engine- and propeller-induced left turning tendencies, but I don't think anyone's addressed the exact situation your instructor gave you that piece advice in, namely the crosswind turn in the traffic pattern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At that particular point of the pattern, unless you've extended your upwind leg until you've reached pattern altitude and leveled off, you will still be flying at a relatively slow speed (so flight controls are less effective, including the little rudder trim tab on your vertical stabilizer), with a high engine power setting (so lots of torque and a nice, fast spiraling slipstream), and in a nose-high attitude (so p-factor comes into play in a big way). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these things combine to impart more left-yawing and -rolling tendencies on the aircraft than at just about any other point in the traffic pattern. Quite a few aircraft, in fact, require minimal, if any, inputs to initiate a left turn from this attitude. As you've seen yourself, you might have to add opposite rudder just to keep the aircraft coordinated while it's doing its thing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're looking for more practical demonstrations of this (as well as how this differs from making turns to the right from this attitude), I recommend asking your instructor to give you a brief introduction to chandelles. They're great for demonstrating and understanding the turning tendencies imparted by the engine at different airspeeds and pitch attitudes (and a lot of fun to boot).&lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2016-05-27T01:09:55.420" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27830" PostTypeId="1" AcceptedAnswerId="27831" CreationDate="2016-05-27T03:15:16.570" Score="0" ViewCount="435" Body="&lt;p&gt;I don't understand the FAA's policy for psychiatric medications (&lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item47/amd/antidepressants/&quot; rel=&quot;nofollow&quot;&gt;specifically anti-depressants&lt;/a&gt;). Obviously I'm glad there is oversight into who can obtain a pilot's license for the safety of the pilot, crew, passengers, and the people on the ground. And obviously people need to be in a stable condition before they eligible to fly. But some of these rules sound ridiculous to me.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, they won't approve you to fly while taking a psychiatric medication, but they may approve you to fly if you decide to go off of it for 60 days.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;What?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically if you have a chronic mental health condition, and you are taking a medication for it, and it's working well without side effects, it's better to go off the medication before you try flying? Wouldn't the disease be more apt to return if you were off the medication, than on it? That sounds like a very stupid risk for the FAA to take.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they worried about side-effects? Most of the side effects for modern SSRIs are very limited and/or transient and/or don't apply to flying (like constipation), so I know they can't be worried about those.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they just concerned about withdrawals if you miss a dose? That seems pretty unlikely to happen, and probably less likely to cause trouble than to go off meds entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Basically, I don't get it. It seems that if you are fully-treated for a condition without side effects that you should be eligible to fly, regardless of whatever drugs are put in your body. Honestly, I'd be more concerned if people were taking less medications for passing a test, than what they were on before.&lt;/p&gt;&#xA;" OwnerUserId="14505" LastEditorUserId="62" LastEditDate="2016-05-27T12:45:26.250" LastActivityDate="2016-05-27T12:45:26.250" Title="What is the US FAA concerned about when it comes to psychiatric medications?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27831" PostTypeId="2" ParentId="27830" CreationDate="2016-05-27T04:52:22.037" Score="7" Body="&lt;p&gt;The FAA is concerned that individuals taking anti-depressant medication will not have the mental focus required when juggling multiple tasks in real time in the cockpit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;anti-depressant medications are psychotropic -- They are specifically intended to alter the takers' mental state.  The assumption is that any artificial modification of mental state will negatively impact aeronautical decision making. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The SSRI special issuance protocol requires, among other things, the applicant to demonstrate the ability to quickly and accurately perform multiple tasks simultaneously.  The idea is to make sure that you aren't being slowed down by the medications to the point where you can't make the right decisions rapidly enough to ensure safety of flight.&lt;/p&gt;&#xA;" OwnerUserId="386" LastActivityDate="2016-05-27T04:52:22.037" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27832" PostTypeId="1" CreationDate="2016-05-27T07:49:09.613" Score="4" ViewCount="909" Body="&lt;h1&gt;Safety through understanding of human factors&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;This question is based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/27814/&quot;&gt;https://aviation.stackexchange.com/questions/27814/&lt;/a&gt; and related to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27833/&quot;&gt;How have deep-seated cultural human factors (particularly in east Asia) in the cockpit been successfully managed in the past 20 years?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27835&quot;&gt;To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aviation industry safety has improved as much through better understanding of human factors in the cockpit as it has through advances in science, technology and engineering, to the extent that practitioners in other sectors (from software development to surgery) are interested in how its principles might apply to their own disciplines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aviation practices of this kind that aim to manage or mitigate human factors include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;extensive use of checklists&lt;/li&gt;&#xA;&lt;li&gt;strict rule-following&lt;/li&gt;&#xA;&lt;li&gt;extensive cross-checking&lt;/li&gt;&#xA;&lt;li&gt;health-checking&lt;/li&gt;&#xA;&lt;li&gt;blameless incident analysis&lt;/li&gt;&#xA;&lt;li&gt;eliminating authority gradients that make it hard for junior crew to question decisions&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Aviation practices across different cultures&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;These practices and the ideas behind them have largely emerged from western social cultures, and largely in the civilian post-WWII industry, and to a certain extent exemplify aspects of western politics and culture.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Examples of incidents related to cultural human factors&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;There are many stories (and some are no doubt apocryphal) of how cultural human factors have been involved in incidents. In recent years:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;steep cultural authority gradients:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;a junior first officer reluctant to question an overbearing captain's decisions&lt;/li&gt;&#xA;&lt;li&gt;a timid first officer who failed to realise his remote and taciturn captain had actually &lt;em&gt;died&lt;/em&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;li&gt;attitudes to regulation, and attitudes of family/VIP exceptionalism:&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;the pilot who allowed a teenaged family member to touch controls in the cockpit&lt;/li&gt;&#xA;&lt;li&gt;the pilots who ignored ATC advice to divert in fog because the president and other VIPs were anxious to attend a ceremony&lt;/li&gt;&#xA;&lt;/ul&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;How does cultural difference impinge upon human factors in aviation industry safety?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;How well have they worked (adoption, implementation, outcome) in very different cultures? &lt;/li&gt;&#xA;&lt;li&gt;Has it been particularly hard for them to find acceptance in other cultures (this applies not just to non-western cultures, but also for example to military culture in the west, where levels of authority and hierarchy are very significant)?&lt;/li&gt;&#xA;&lt;li&gt;Have &lt;em&gt;different&lt;/em&gt; approaches been used or tried with better results, in different cultures?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-06-23T08:05:42.857" Title="How does cultural difference impinge upon human factors in aviation industry safety?" Tags="&lt;safety&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27833" PostTypeId="1" CreationDate="2016-05-27T08:04:56.517" Score="7" ViewCount="519" Body="&lt;p&gt;This question is based on &lt;a href=&quot;https://aviation.stackexchange.com/questions/27814/&quot;&gt;https://aviation.stackexchange.com/questions/27814/&lt;/a&gt; and related to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27832/&quot;&gt;How does cultural difference impinge upon human factors in aviation industry safety?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27835&quot;&gt;To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Successful management of cultural human factors&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;East Asian airlines used to have poor safety records, notably KAL and Chinese airlines, in part because of cultural human factors in the cockpit (hence the disquiet in Korea over &lt;a href=&quot;http://www.bbc.co.uk/news/world-asia-30390724&quot; rel=&quot;noreferrer&quot;&gt;the notorious nut rage incident in 2014&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The last two decades have seen considerable improvements in these safety records.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To the extent that the improvements have been related to better management of human factors (rather than say better technical resources and practices) what approaches have been successful in managing these cultural factors to improve safety (and to what extent)?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2018-10-02T13:47:53.143" Title="How have deep-seated cultural human factors (particularly in east Asia) in the cockpit been successfully managed in the past 20 years?" Tags="&lt;safety&gt;&lt;human-factors&gt;" AnswerCount="1" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27834" PostTypeId="2" ParentId="27823" CreationDate="2016-05-27T08:08:43.810" Score="8" Body="&lt;p&gt;There are already good answers, so I won't dwell on the standard advice to look at the slip indicator and do the necessary, but I'll answer to clear up a possible misunderstanding.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You &lt;strong&gt;do not&lt;/strong&gt; use rudder to correct for adverse yaw &lt;strong&gt;when turning&lt;/strong&gt;. You use rudder to correct for adverse yaw &lt;strong&gt;when rolling into&lt;/strong&gt; the turn. When you turn left, you put the stick left to roll to the correct bank angle, and then you put the stick in the centre to maintain that bank angle throughout the turn. While the stick is on the left, you should be applying left rudder, but as the stick goes back towards the centre, so you should be reducing the left rudder. You don't keep that left rudder in for the whole turn. Later, when you roll out of the turn, you use right rudder then while your stick is on the right, and then return the rudder to the centre when you return the stick to the centre.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you're turning across the wind direction, you'll definitely need to adjust the rudder position because the direction of the airflow against the aircraft changes. Exactly what is different in different situations (of wind direction and turn direction). Once you've completed the roll, you need to use the correct rudder for the situation. The fact you're in a left turn doesn't mean you can only use left rudder.&lt;/p&gt;&#xA;" OwnerUserId="998" LastEditorUserId="13937" LastEditDate="2016-05-27T14:26:10.957" LastActivityDate="2016-05-27T14:26:10.957" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27835" PostTypeId="1" CreationDate="2016-05-27T08:14:54.767" Score="10" ViewCount="702" Body="&lt;p&gt;This question is related to:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27832/&quot;&gt;How does cultural difference impinge upon human factors in aviation industry safety?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/questions/27833&quot;&gt;How have deep-seated cultural human factors (particularly in east Asia) in the cockpit been successfully managed in the past 20 years?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Standard industry practices of cockpit management can invert or disrupt very deep cultural and political expectations of command and authority.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The question&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;What &lt;strong&gt;evidence&lt;/strong&gt; is there, &lt;strong&gt;in research, incident reports or other documented sources&lt;/strong&gt;, &lt;em&gt;that has identified political attitudes around race, gender or social class as human factors in the cockpit&lt;/em&gt;?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;With more women in airline cockpits, have new human factors emerged (for example, a male pilot displeased to be questioned by a woman)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In regions with troubled racial histories (southern Africa, the USA) have race relations and attitudes in the cockpit been responsible for incidents?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cultures where social class or even caste is very significant, have these been implicated as human factors in the cockpit?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="14897" LastEditDate="2019-02-13T20:25:20.533" LastActivityDate="2019-03-06T07:19:00.837" Title="To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?" Tags="&lt;safety&gt;&lt;human-factors&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="27836" PostTypeId="2" ParentId="27832" CreationDate="2016-05-27T08:26:05.410" Score="8" Body="&lt;p&gt;What you are asking looks like a university assignment on Interface design and sociology. It is a very complex area and your question does not suggest a simple answer but here goes:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These cultural factors are covered by Hofstead's theory of Cultural dimensions. Specifically the Cultural factors of Power Distance, Individualism and Uncertainty Avoidance. I have studied Hofstead (and others) and its relation to Interaction Design and Interface Design for a computing degree.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Power Distance (PD). The higher the score then the more likely the culture is to vest  power in an elite and accept that their decisions. The lower the score the more power is devolved and people are more likely to question leaders.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Individualism (IND). The higher the score the the more loose the societal structure. The lower it is then the society tend to collectivism and rigid structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Uncertainty Avoidance (UA). The higher the score then the more the society prefers rigid rules and procedures for all events. The lower then the more relaxed the society is to rules unexpected events.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that these overlap considerably.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What this means is that cultures with high PD, UA or Low IND are more likely to follow instruction or even crave instruction and rule. Checklists and instructions are more likely to be followed. Cultures with the opposite may be inclined to be a little more relaxed and may be more of a risk to safety due to a laissez-faire attitude to checks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However a high PD, low IND and high UA may result in a subordinate unquestioningly accepting instruction from the captain despite knowing that the order was wrong even to the point of crashing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is a massively complex subject and to get an answer you really need to be specific with scenarios and cultures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To see the scores for various cultures then go to &lt;a href=&quot;https://geert-hofstede.com/countries.html&quot;&gt;geert-hofstede.com/countries.html&lt;/a&gt; and try some countries&lt;/p&gt;&#xA;" OwnerUserId="14127" LastEditorUserId="19" LastEditDate="2016-05-27T09:15:17.940" LastActivityDate="2016-05-27T09:15:17.940" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27837" PostTypeId="1" CreationDate="2016-05-27T09:10:00.313" Score="4" ViewCount="1349" Body="&lt;p&gt;Why is the afterburner flame of some fighter aircraft blue while for some it is orange?&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="1467" LastEditDate="2017-04-07T10:59:48.037" LastActivityDate="2017-04-07T10:59:48.037" Title="Why is the reheat exhaust flame of some fighter aircraft blue while for some it is orange?" Tags="&lt;jet-engine&gt;&lt;fighter&gt;" AnswerCount="1" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27838" PostTypeId="1" CreationDate="2016-05-27T09:51:51.327" Score="4" ViewCount="1176" Body="&lt;p&gt;As far as I know, jets did not see mass production across the world until the 1950's. So I'm interested in how they were built in that time. How many different types of factories were needed? How did those factories work? What supplies were needed and how much manpower did they need per jet?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Right now I'm only imagining two kinds, an airframe factory and an engine factory. I'm very interested in learning more and would not be surprised if there are many other types of factories that go into making a fighter jet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For simplicity, let's exclude electronics factories like the radar, and weapons factories like guns, bullets, and missiles.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2017-04-07T10:59:21.180" LastActivityDate="2019-11-05T04:26:39.707" Title="How were fighter jets built in the 1950's?" Tags="&lt;military&gt;&lt;aviation-history&gt;&lt;jet&gt;&lt;fighter&gt;&lt;plane-construction&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27839" PostTypeId="1" AcceptedAnswerId="27840" CreationDate="2016-05-27T10:06:06.660" Score="12" ViewCount="1934" Body="&lt;p&gt;Let's say there are two aircraft in a risk of collision, one of them is equipped with Traffic Collision Avoidance System (TCAS) I so it will get only a Traffic Advisory (TA), however the second one is equipped  with TCAS II, and it will get both TA and Resolution Advisory (RA). What is the procedure to be followed if there is a risk of collision, the TCAS II aircraft must follow the RA, and the TCAS I must follow the ATC instructions or what is the procedure in this case?&lt;/p&gt;&#xA;" OwnerUserId="12552" LastEditorUserId="1696" LastEditDate="2016-05-27T17:19:04.363" LastActivityDate="2016-08-20T20:32:50.607" Title="How is a conflict between aircraft with TCAS I and II resolved?" Tags="&lt;air-traffic-control&gt;&lt;instrument-flight-rules&gt;&lt;flight-instruments&gt;&lt;instrument-procedures&gt;&lt;tcas&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27840" PostTypeId="2" ParentId="27839" CreationDate="2016-05-27T10:32:31.073" Score="15" Body="&lt;p&gt;TCAS 1 will only give a Traffic Advisory (TA). The crew will lookout for the other aircraft and take evasive action if necessary. They also may contact ATC for instructions. They will follow ATC instructions unless they see that the instructions will bring them into the path of the other aircraft.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS II will give a traffic advisory first, then a Resolution Advisory (RA). The crew has to follow the resolution advisory and inform ATC of their maneuvering (e.g. TCAS climb, Big Jet 123). They are trained not to follow ATC instructions that oppose the TCAS RA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that TCAS II RA's are always in the vertical plane; TCAS II can not give instructions to turn. &lt;/p&gt;&#xA;" OwnerUserId="19" LastEditorUserId="8490" LastEditDate="2016-08-20T20:32:50.607" LastActivityDate="2016-08-20T20:32:50.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27842" PostTypeId="2" ParentId="27837" CreationDate="2016-05-27T13:45:35.817" Score="4" Body="&lt;p&gt;I agree with Simon's comments. Lighting and ambient lights make &lt;em&gt;all the difference&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The flame is always equally bright, so if the ambient light is lower, the difference between the flame and the rest of the image is larger. When the difference exceeds the dynamic range of the film or sensor, the image of the flame becomes saturated in all channels and ends up as white. Note, that all the images with white flame are night ones.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also the blue sensor is slightly sensitive to near infrared (being about half wavelength of the blue light), so when high sensitivity/long time are used, this causes the blue glow around the white flames on night images, while on day images with lower sensitivity it is not noticeable.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-05-27T14:17:46.260" LastActivityDate="2016-05-27T14:17:46.260" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27843" PostTypeId="2" ParentId="27838" CreationDate="2016-05-27T14:53:57.990" Score="8" Body="&lt;p&gt;Building an airframe did not change all that much in the jet age. Assuming you are talking about all aluminum aircraft the power plant is somewhat abstracted from the equation in terms of a production line. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is the assembly line that Lockheed had for the early &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_P-80_Shooting_Star&quot; rel=&quot;noreferrer&quot;&gt;P-80 Jets&lt;/a&gt; (not all that different than &lt;a href=&quot;http://spitfiresite.com/wp-content/uploads/2012/07/23-23-7557926480_17cc030455_k.jpg&quot; rel=&quot;noreferrer&quot;&gt;their propellor counter parts&lt;/a&gt;). This picture would make it seem as though the airframe was all built in one place as you can see it in various stages in this image alone.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/adKDn.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/adKDn.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://l7.alamy.com/zooms/186583e235f14936b1af798875baa500/lockheed-p-80-production-line-1945-lockheed-ad-869-via-rjf-f2f53g.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is a &lt;a href=&quot;http://www.airspacemag.com/history-of-flight/shooting-star-180952799/?no-ist&quot; rel=&quot;noreferrer&quot;&gt;pretty interesting article about the history of the plane&lt;/a&gt; and the role Kelly Johnson played in it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Like anything in the world of production the assembly line does not change nearly as much as the tooling does. One of main costs in bringing anything to production is cutting and preparing the tooling. Assembling a jet airframe was not all to different than assembling a high performance prop plane of the era. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Things got more complex as they moved to more complicated materials (this came a bit later than your question references but none the less). By all accounts an &lt;a href=&quot;https://www.youtube.com/watch?v=d8I7MLD0YZQ&quot; rel=&quot;noreferrer&quot;&gt;enormous portion of the SR-71 Blackbird budget was spent developing tooling that could work with titanium&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The engine companies (Like GE/P&amp;amp;W etc) saw much bigger changes as they were now making and testing a completely different product. The P-80 above housed a &lt;a href=&quot;https://en.wikipedia.org/wiki/Allison_J33&quot; rel=&quot;noreferrer&quot;&gt;GE/Allison J33&lt;/a&gt;. This would have fallen on to GE to build and like many engines prior would have simply been bought by Lockheed for the plane. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I will try and find some hard production numbers/times for this era of planes. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastActivityDate="2016-05-27T14:53:57.990" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27844" PostTypeId="1" CreationDate="2016-05-27T16:24:53.300" Score="8" ViewCount="9930" Body="&lt;p&gt;I would like to know the difference between marginal VFR (MVFR) and Special VFR (SVFR), particularly when flying in the US airspace. What does each of them mean exactly?&lt;/p&gt;&#xA;" OwnerUserId="14891" LastEditorUserId="62" LastEditDate="2016-05-27T17:13:25.620" LastActivityDate="2020-12-05T04:41:50.870" Title="What is the difference between Marginal VFR (MVFR) and Special VFR (SVFR)?" Tags="&lt;faa-regulations&gt;&lt;weather&gt;&lt;visual-flight-rules&gt;&lt;special-vfr&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27845" PostTypeId="2" ParentId="27844" CreationDate="2016-05-27T17:03:01.823" Score="7" Body="&lt;p&gt;&lt;strong&gt;Marginal VFR&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Straight out of the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_00-45G_CHG_1-2.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation Weather Services advisory circular (AC 00-45G with changes 1 and 2)&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;Marginal Visual Flight Rules (MVFR) indicated on the Weather Depiction&#xA;Chart represents ceiling 1,000 to 3,000 feet and/or visibility 3 to 5&#xA;statute miles and VFR operations can take place. MVFR areas are&#xA;outlined with a solid line, but the area is not shaded. MVFR areas are&#xA;typically shaded blue in colorized versions of the chart.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;For all regulatory purposes, this has no rule changes from VFR.  I believe the reason it exists is for pilots to more easily identify areas where the weather conditions are approaching IMC.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Special VFR in the US&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1157&quot; rel=&quot;nofollow noreferrer&quot;&gt;Special VFR&lt;/a&gt; allows a pilot to fly within the lateral boundaries of controlled airspace to the ground with &lt;em&gt;at least 1SM visibility and clear of clouds.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;Special VFR is something that can be granted by ATC upon request by a pilot.  It may only be granted within the lateral boundaries of &lt;em&gt;controlled airspace that goes to the ground.&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;If the special VFR request is being made at night, the pilot and airplane must be IFR legal.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/documentLibrary/media/Order/7110.65Y_ATC_Bsc_w_Chg_1_2_dtd_7-16-20.pdf#page=357&quot; rel=&quot;nofollow noreferrer&quot;&gt;JO 7110.65Y Section Regarding Special VFR&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;em&gt;&lt;strong&gt;There is no requirement that the weather conditions being reported are below basic VFR.&lt;/strong&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/n2aQo.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/n2aQo.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;The Difference&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;MVFR is an advisory term.&lt;/p&gt;&#xA;&lt;p&gt;Special VFR is an, on request by pilot only, &amp;quot;required weather minimums&amp;quot; change that may be approved by ATC.&lt;/p&gt;&#xA;&lt;p&gt;For the purposes of special VFR in the US, here is the FAA regulation. (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_1157&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.157&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2020-12-05T04:41:50.870" LastActivityDate="2020-12-05T04:41:50.870" CommentCount="6" ContentLicense="CC BY-SA 4.0" />
  <row Id="27846" PostTypeId="1" AcceptedAnswerId="27847" CreationDate="2016-05-27T17:54:54.343" Score="17" ViewCount="2934" Body="&lt;p&gt;This probably sounds like a silly question, but I was watching floatplanes land on Lake Union, Seattle, and it got me wondering whether a plane that touches down onto water is still talked about as &quot;landing&quot; in aviation parlance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it?&lt;/p&gt;&#xA;" OwnerUserId="14835" LastEditorUserId="14835" LastEditDate="2016-05-28T19:02:57.683" LastActivityDate="2016-05-28T19:02:57.683" Title="Is it still &quot;landing&quot; in a seaplane?" Tags="&lt;landing&gt;&lt;terminology&gt;&lt;seaplane&gt;" AnswerCount="3" CommentCount="11" ContentLicense="CC BY-SA 3.0" />
  <row Id="27847" PostTypeId="2" ParentId="27846" CreationDate="2016-05-27T18:03:12.120" Score="19" Body="&lt;p&gt;Yes. One 'official' example is from the FAA's &lt;a href=&quot;https://www.faa.gov/training_testing/testing/test_standards/media/FAA-S-8081-14B.pdf&quot;&gt;test standards&lt;/a&gt; for land and seaplanes, which includes these tasks for seaplanes:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Task H: Glassy Water Approach and Landing&lt;br&gt;&#xA;  [...]&lt;br&gt;&#xA;  Task J: Rough Water&#xA;  Approach and Landing&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA's &lt;em&gt;&lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook/&quot;&gt;Seaplane, Skiplane, and Float/Ski Equipped Helicopter Operations Handbook&lt;/a&gt;&lt;/em&gt; also uses it; Chapter 6 is called &quot;Seaplane Operations - Landings&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Interestingly, the word &quot;landing&quot; itself isn't defined in the FAA's &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/pcg.pdf&quot;&gt;glossary&lt;/a&gt; or in &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=14:1.0.1.1.1.0.1.1&quot;&gt;14 CFR 1.1&lt;/a&gt; (the US air regulations general definitions). Presumably it's considered to be too 'obvious' to require a definition.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-05-27T19:07:29.543" LastActivityDate="2016-05-27T19:07:29.543" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27848" PostTypeId="1" AcceptedAnswerId="27908" CreationDate="2016-05-27T18:21:18.963" Score="5" ViewCount="24987" Body="&lt;p&gt;I think I understand the relationship between the power lever and the RPM lever in an aircraft with a constant speed prop thanks to this &lt;a href=&quot;https://aviation.stackexchange.com/questions/9333/how-do-throttle-control-and-propeller-control-work-together&quot;&gt;question&lt;/a&gt;. However, what'd be a general rule of thumb for flying a small aircraft (e.g. Cessna 170) that has a variable-pitch propeller?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit:&#xA;I'm flying a Cessna 170 that has been modified to fit a constant speed prop. What I'm trying to determine are the general recommendations for flying with them. Things like: On takeoff you should use full power &amp;amp; full rpms, on cruise lower power to 75% but keep full  rpms, etc. I'm not sure if there are general recommendations to begin with.&lt;/p&gt;&#xA;" OwnerUserId="15144" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2018-07-13T00:33:21.527" Title="What's the rule of thumb for power and rpm in a constant speed prop?" Tags="&lt;general-aviation&gt;&lt;constant-speed-propeller&gt;" AnswerCount="4" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27849" PostTypeId="1" AcceptedAnswerId="30270" CreationDate="2016-05-27T18:22:12.670" Score="0" ViewCount="707" Body="&lt;p&gt;Looking at the stats breakdown on Wikipedia &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Merlin#Specifications_.28Merlin_61.29&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; for the Merlin 61 series reciprocating engines used in Spitfire planes, I noticed that maximum horsepower is given at approximately 3000 RPM. But AirPages has what looks like a manual &lt;a href=&quot;http://www.airpages.ru/eng/mt/merlin01.shtml&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt; that lists the &lt;em&gt;maximum&lt;/em&gt; RPM as 3000.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are they simply stating that the same thing: that torque starts to fall off at 3000 RPM? Or are they saying that the engine is just physically incapably of spinning faster than 3000 RPM (seems unlikely)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the case of the first one, what &lt;em&gt;is&lt;/em&gt; the (approximate) redline for one of these engines?&lt;/p&gt;&#xA;" OwnerUserId="3484" LastEditorUserId="19" LastEditDate="2016-06-24T10:42:42.280" LastActivityDate="2016-07-24T18:56:29.960" Title="Is the maximum power the Merlin 61 reciprocating engine occuring at its maximum RPM?" Tags="&lt;aircraft-systems&gt;&lt;piston-engine&gt;&lt;spitfire&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27850" PostTypeId="2" ParentId="27849" CreationDate="2016-05-27T18:32:18.050" Score="0" Body="&lt;p&gt;Maximum RPM and Red Line RPM are the same thing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They can be exceeded but not without the chance of engine damage. &lt;/p&gt;&#xA;" OwnerUserId="12589" LastActivityDate="2016-05-27T18:32:18.050" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27851" PostTypeId="2" ParentId="27848" CreationDate="2016-05-27T18:44:07.617" Score="2" Body="&lt;p&gt;Most aircraft today either have a fixed pitch propeller, or have constant speed propellers where the RPM is controlled by a governor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some aircraft have ground adjustable propellers, or manually controllable, variable pitch propellers, but they are pretty rare these days.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cessna 170's were all built with fixed pitch propellers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is possible to modify the C170 to a constant speed propellor but the engine would need to be changed, or modified, in order to supply oil pressure to the prop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you were to install a constant speed propeller in a C170 it would be operated just as any other light aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You should always follow the manufacturer's procedures but a general rule for direct drive normally aspirated engines is to keep the manifold pressure less than the RPM for cruise power. (eg. 24 inches of MP at 2400 RPM) &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2018-07-13T00:33:21.527" LastActivityDate="2018-07-13T00:33:21.527" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="27852" PostTypeId="2" ParentId="27848" CreationDate="2016-05-27T18:45:33.667" Score="2" Body="&lt;p&gt;The general rule of thumb that I am familiar with is 2400RPM set by the &lt;strong&gt;governor control lever&lt;/strong&gt; and 23in-Hg for manifold pressure set by the throttle lever.  This is what we do in a Diamond DA-40, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen the same settings used in other small aircraft, but I am sure there are variations between models.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-05-27T18:51:00.210" LastActivityDate="2016-05-27T18:51:00.210" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27853" PostTypeId="2" ParentId="27846" CreationDate="2016-05-27T18:50:08.930" Score="4" Body="&lt;p&gt;No. ICAO defines a landing like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;From the beginning of the landing flare until aircraft exits the landing &lt;strong&gt;runway&lt;/strong&gt;, comes to a stop on the &lt;strong&gt;runway&lt;/strong&gt;, or when power is applied for takeoff in the case of a touch-and-go landing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.intlaviationstandards.org/Documents/PhaseofFlightDefinitions.pdf&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And a runway like this:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A defined rectangular area &lt;strong&gt;on a land aerodrome&lt;/strong&gt; prepared for the landing and take-off of aircraft&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;(&lt;a href=&quot;http://www.icao.int/safety/implementation/library/manual%20aerodrome%20stds.pdf&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wikipedia suggests that &quot;landing&quot; on water is referred to as &quot;alighting&quot;&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-05-27T18:50:08.930" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27854" PostTypeId="2" ParentId="27846" CreationDate="2016-05-27T20:10:56.790" Score="10" Body="&lt;p&gt;Not in French it isn't. French for landing is 'aterrir' which roughly translates to 'return to the land'. Using this verb for a sea 'landing' would sound silly to them so they use 'amerrir' which means 'return to the sea' (Mer being French for sea, terre is French for ground). A landing in the Moon would be 'alunir'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This interesting fact was mentioned by the instructor on my French audio course.&lt;/p&gt;&#xA;" OwnerUserId="14244" LastEditorUserId="14244" LastEditDate="2016-05-27T21:34:03.097" LastActivityDate="2016-05-27T21:34:03.097" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27858" PostTypeId="2" ParentId="27839" CreationDate="2016-05-27T21:19:31.927" Score="5" Body="&lt;p&gt;According to &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_120-55c_chg_1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 120-55C&lt;/a&gt;, the TCAS II aircraft will issue a TA (Traffic Advisory) and an RA (Resolution Advisory) if necessary and the pilot should follow any RA immediately and safely.  The TCAS I aircraft should attempt to establish visual contact and maintain a safe distance from the other aircraft while following good operating procedures and ATC clearance. TCAS I only offers information about the traffic around the aircraft and does not give RA's.  Meanwhile the TCAS II aircraft will see the TCAS I aircraft but will not expect the intruder to follow RA's or coordinate TCAS behavior, similar to if the TCAS I aircraft had only a mode C transponder or had TCAS II but with &quot;TA only&quot; active.  See the table below for response details:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dnxSU.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dnxSU.png&quot; alt=&quot;TCAS Resolution Levels&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/TCAS%20II%20V7.1%20Intro%20booklet.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Table Source&lt;/a&gt;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The behavior on the TCAS II aircraft is not all that different than if both were TCAS II equipped and the aircraft in question was the first to issue a Resolution Advisory (RA).   The first aircraft will select an RA direction (up or down) that gives the most vertical separation from the intruder.  The RA direction and strength for the first aircraft is calculated independently of the expected TCAS response of the intruder, except in a few exceptional cases.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You will not get coordinated behavior if one of aircraft is TCAS I equipped, but coordination only applies when the other aircraft has already issued an RA or an RA reversal is necessary.  To give a brief description of coordination, normally the two TCAS II aircraft issue RA's at a slightly different time, and the first to declare an RA sends an &quot;intent message&quot; to the other to prevent it from issuing a contradictory RA. Coordination will also send a message during an RA reversal indicating that the other plane should follow the reversal. The exact details of coordination is beyond the scope of this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS II and TCAS I will also have slightly different requirements for displaying a TA.  For example, the logic was adjusted in TCAS II v7.0 to reduce thresholds for RVSM airspace.  So the TA may be displayed on one plane when it is not displayed on the other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is important as well to remember the cardinal rules of TCAS:  Always immediately and safely follow an RA (except in cases of stall or terrain), but do not deviate from ATC clearance and good operating procedures just to avoid a TA.    The &lt;a href=&quot;https://en.wikipedia.org/wiki/%C3%9Cberlingen_mid-air_collision&quot; rel=&quot;nofollow noreferrer&quot;&gt;Uberlingen mid-air collision&lt;/a&gt; underscored the importance of following an RA and not ATC.  The crash was caused by one plane following the RA and the other following conflicting ATC guidance. See &lt;a href=&quot;http://www.faa.gov/documentlibrary/media/advisory_circular/ac_120-55c_chg_1.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AC 120-55C&lt;/a&gt; for more details on expected pilot response to TCAS.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;TCAS logic is complicated when you get into the inner workings.  I'd recommend reading the &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/TCAS%20II%20V7.1%20Intro%20booklet.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA's guide&lt;/a&gt; for more details.  Most of this information comes from that booklet.  &lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="14613" LastEditDate="2016-05-27T23:25:12.340" LastActivityDate="2016-05-27T23:25:12.340" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27859" PostTypeId="1" AcceptedAnswerId="27860" CreationDate="2016-05-27T22:29:13.237" Score="4" ViewCount="133" Body="&lt;p&gt;I got caught in gusty cross wind on the  final approach to Catalina airport last week and decided to add power and push for quick turn to come back over laterally sliding runway in a Cessna 172N. Later I was thinking back about the distribution of wind and lift pressure on the wings and could imagine a loading that would be directed upward under my left wing but changing downward on at least part of my right wing. Imagine that you're viewing the plane from behind and see it like a catamaran banked into 30' angle. And a horizontal line not necessarily passing through center crossing it as the sea water level. Is it possible and what to do to handle it? &lt;/p&gt;&#xA;" OwnerUserId="9265" LastEditorUserId="19" LastEditDate="2016-11-01T11:54:22.330" LastActivityDate="2016-11-01T11:54:22.330" Title="Is there any load and balance and attitude that can put positive G on one wing and negative on the other?" Tags="&lt;cessna-172&gt;&lt;crosswind&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27860" PostTypeId="2" ParentId="27859" CreationDate="2016-05-27T23:53:48.080" Score="4" Body="&lt;p&gt;Just imagine an aerobatic aircraft going straight up and rolling at the same trime - sure it will have positive lift on one side and negative on the other while accelerating into the roll or when stopping the rolling motion. Note that during a constant rolling motion while in a vertical climb the overall rolling moment and the &lt;a href=&quot;https://aviation.stackexchange.com/questions/12742/why-do-planes-not-fly-backwards-up-from-the-planes-pov-when-in-a-vertical-cl/12743#12743&quot;&gt;overall lift&lt;/a&gt; both are zero.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, wing twist will cause very little lift or even a small downforce at the wingtip at low angle of attack. I remember that the wingtips of the &lt;a href=&quot;http://www.akaflieg-braunschweig.de/prototypen/sb8/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SB-8&lt;/a&gt; and &lt;a href=&quot;http://www.akaflieg-braunschweig.de/prototypen/sb10/&quot; rel=&quot;nofollow noreferrer&quot;&gt;SB-10&lt;/a&gt; gliders would point downwards from the negative lift at high speed. The high aspect ratio glass fiber wing would bend a lot and indicate the local lift with a local change in curvature.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, if you were flying an approach, the aircraft should have flown too slowly to allow for that condition, unless it also started to roll violently from the lift asymmetry. If you had to apply full aileron to counter a gust-induced rolling moment, that very aileron deflection would avoid any negative lift on one of the wingtips. This only leaves the possibility that you had negative lift for a very short moment and over a small part of the wing when the gust hit you and before you countered the rolling motion with the ailerons.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-27T23:53:48.080" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27861" PostTypeId="1" CreationDate="2016-05-28T00:30:17.200" Score="2" ViewCount="221" Body="&lt;p&gt;I was checking out some flights on FlightAware and went onto the &quot;Route&quot; page for a flight and I saw these &lt;a href=&quot;http://www.cfinotebook.net/notebook/aircraft-operations/enroute/reporting&quot; rel=&quot;nofollow noreferrer&quot;&gt;IFR Reporting Points&lt;/a&gt; with really odd names. Is there a regulatory reason why they have such names?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sq54B.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sq54B.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://flightaware.com/live/flight/UAL779/history/20160527/2035Z/KSFO/KEWR/route&quot; rel=&quot;nofollow noreferrer&quot;&gt;Page I snipped image from&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastEditorUserId="62" LastEditDate="2016-05-28T15:18:18.270" LastActivityDate="2016-05-28T15:18:18.270" Title="Why do IFR reporting points have odd names?" Tags="&lt;faa-regulations&gt;&lt;navigation&gt;&lt;ifr-navigation&gt;" AnswerCount="0" CommentCount="7" ClosedDate="2016-05-28T19:57:00.317" ContentLicense="CC BY-SA 3.0" />
  <row Id="27864" PostTypeId="1" CreationDate="2016-05-28T07:22:44.247" Score="5" ViewCount="846" Body="&lt;p&gt;The nozzles of the Sukhoi T-50 seem to be aligned not perfectly parallel. However, it is not very pronounced.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What may be the reasons for aligning the &lt;s&gt;nozzles&lt;/s&gt; engines not perfectly parallel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; in my original post I asked about the nozzles, however, as it was pointed out, this plane used 3D thrust vectoring, so the nozzle arrangement might be this way by chance. However, also the engines seem to be aligned not perfectly parallel. The question has been edited accordingly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/oOhY9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oOhY9.jpg&quot; alt=&quot;Suchoi T-50&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://commons.wikimedia.org/wiki/Category:T-50-2_%28aircraft%29#/media/File:Sukhoi_T-50_at_the_MAKS-2013_%2801%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source Wikimedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit 2:&lt;/strong&gt; Here is another picture &lt;a href=&quot;https://i.stack.imgur.com/60R5q.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/60R5q.jpg&quot; alt=&quot;of a PAK-FA with a Mig-29&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://commons.wikimedia.org/wiki/File:Sukhoi_T-50_in_2012_%285%29.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Image source, Wikipedia again&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9892" LastEditorUserId="15311" LastEditDate="2017-12-23T22:16:12.610" LastActivityDate="2017-12-23T22:16:12.610" Title="Why do the engines of the PAK FA (Sukhoi T-50) seem not to be not aligned parallel to each other?" Tags="&lt;aircraft-design&gt;&lt;fighter&gt;&lt;russia&gt;&lt;sukhoi-pak-fa&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27865" PostTypeId="1" CreationDate="2016-05-28T07:38:00.767" Score="1" ViewCount="1193" Body="&lt;p&gt;I've tested my RC plane yesterday. It's a canard. After hand launching, the plane goes straight, then I change the elevator to go down and it's going down, but when I pitch up the canard doesn't work and the plane crashes.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The plane is at full throttle.&lt;/li&gt;&#xA;&lt;li&gt;When diving the plane slightly rotates to right.&lt;/li&gt;&#xA;&lt;li&gt;Controls tested before flight.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Airfoil is a NACA 2412, but tips gets a little thick (all cutting, sanding is done by hand)&lt;/li&gt;&#xA;&lt;li&gt;No incidences.&lt;/li&gt;&#xA;&lt;li&gt;One servo for the canard and one servo for the ailerons. &lt;/li&gt;&#xA;&lt;li&gt;No thrust angle.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The plane:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/oqujy.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oqujy.png&quot; alt=&quot;RC plane with canard&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CG is just in front of the vertical stabilizer (the little cross in the image)&lt;/p&gt;&#xA;" OwnerUserId="13066" LastEditorUserId="1696" LastEditDate="2016-05-28T21:42:05.950" LastActivityDate="2016-06-01T18:09:56.033" Title="Why does this plane not pitch up after a dive?" Tags="&lt;model-aircraft&gt;" AnswerCount="4" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27867" PostTypeId="1" AcceptedAnswerId="27917" CreationDate="2016-05-28T08:36:03.920" Score="3" ViewCount="395" Body="&lt;p&gt;The most obvious way to verify if birds are stable or not in at least gliding flight would be to make the exact rigid model of the bird (including weight distribution) and launch it into flight. The simplest approach that even early aircraft inventors may have tried is to use a frozen real bird.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are there any references about anybody trying such experiments? Pure logical or mathematical analysis is outside the topic of this question. &lt;/p&gt;&#xA;" OwnerUserId="917" LastEditorUserId="917" LastEditDate="2016-05-28T14:11:39.227" LastActivityDate="2016-05-31T12:35:06.923" Title="Has anybody done gliding experiments with exact replicas of the birds or other real world flying creatures?" Tags="&lt;aerodynamics&gt;&lt;stability&gt;&lt;birds&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27868" PostTypeId="2" ParentId="27865" CreationDate="2016-05-28T10:18:48.380" Score="3" Body="&lt;p&gt;I would suspect a combination of a very nose heavy CG, and not enough up elevator control throw, but it's impossible to determine based on the information given. &lt;/p&gt;&#xA;" OwnerUserId="12116" LastActivityDate="2016-05-28T10:18:48.380" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27869" PostTypeId="2" ParentId="27867" CreationDate="2016-05-28T11:05:42.737" Score="7" Body="&lt;p&gt;The closest I know of are several attempts to build &lt;a href=&quot;http://www.pterosaur.org.uk/PDB2012/T/Flying/Flying01.htm&quot; rel=&quot;nofollow&quot;&gt;models of pterosaurs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since the head with its long beak is ahead of their center of gravity, the configuration is statically unstable in yaw and needs continuous control corrections. On the other hand, this instability provides very quick responses. &lt;a href=&quot;https://www.youtube.com/watch?v=MzFCIc2gfJk&quot; rel=&quot;nofollow&quot;&gt;This YouTube movie&lt;/a&gt; contains footage of a Pterodactyl model made by &lt;a href=&quot;https://en.wikipedia.org/wiki/Paul_MacCready&quot; rel=&quot;nofollow&quot;&gt;Paul MacCready&lt;/a&gt; in flight. Note that Paul had attached a conventional tail for the first flights to statically stabilize the model in pitch and yaw. Later in the flights this tail was removed. The small skin area between the legs was most likely not sufficient for pitch stabilization, and small changes in wing sweep were used to stabilize the animals in pitch, just like modern birds still do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another branch, the &lt;a href=&quot;http://en.wikipedia.org/wiki/Rhamphorhynchoidea&quot; rel=&quot;nofollow&quot;&gt;Rhamphorhynchoidea&lt;/a&gt;, had a tail which provided additional lateral and longitudinal control. Palaeobiologists are still arguing, however, whether the tip of the tail was oriented horizontally or vertically in flight.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="1961" LastEditDate="2016-05-31T12:35:06.923" LastActivityDate="2016-05-31T12:35:06.923" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27870" PostTypeId="2" ParentId="27864" CreationDate="2016-05-28T11:26:59.610" Score="5" Body="&lt;p&gt;The Sukhoi T-50 operates Thrust vectoring nozzle control at low speeds. The nozzles are a part of the Fly By Wire system and will deflect as per the control input given by the pilot. The nozzles move in coordination with other flight controls and it is not necessary for them to be parallel in all conditions of flight. However on the ground they will appear to be parallel. &lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="5517" LastEditDate="2016-05-31T12:47:49.753" LastActivityDate="2016-05-31T12:47:49.753" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27872" PostTypeId="2" ParentId="27867" CreationDate="2016-05-28T18:44:36.173" Score="2" Body="&lt;p&gt;I don't know about birds but researchers have been working for a long time to replicate insect flight. &lt;a href=&quot;http://www.wired.com/2011/03/flying-robot-insects/&quot; rel=&quot;nofollow&quot;&gt;This&lt;/a&gt; article talks about how 3D printing has made this much easier. It has a video of a working replica hovering. They call it an &lt;em&gt;ornithopter.&lt;/em&gt; Technically &quot;ornitho-&quot; means &quot;bird,&quot; but I guess &lt;em&gt;entomopter&lt;/em&gt; didn't have the right ring to it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I remember reading something back in the 80's about spy agencies trying to develop a &quot;fly on the wall&quot; cyber-insect that could get in through air ducts or other tight spaces. &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="8730" LastEditDate="2016-05-28T22:38:35.493" LastActivityDate="2016-05-28T22:38:35.493" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27873" PostTypeId="1" AcceptedAnswerId="27878" CreationDate="2016-05-28T22:08:22.920" Score="2" ViewCount="881" Body="&lt;p&gt;While taking my pre-solo exam, I noticed my medical has my birth date one year earlier than it actually is. I am expecting to solo tomorrow. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would this error legally prohibit me from soloing until it is corrected?&lt;/p&gt;&#xA;" OwnerUserId="15156" LastEditorUserId="14661" LastEditDate="2016-05-29T09:30:57.063" LastActivityDate="2016-05-29T09:30:57.063" Title="What should I do to resolve an incorrect birth date on my FAA medical certificate?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27874" PostTypeId="1" CreationDate="2016-05-28T22:14:35.637" Score="0" ViewCount="810" Body="&lt;p&gt;For example, I completed my CPL multi and have 300 flight hours, can I do a A320 type rating and work for an airline if they allowed my to work with 300 hours?&lt;/p&gt;&#xA;" OwnerUserId="15155" LastEditorUserId="19" LastEditDate="2016-06-21T16:07:47.367" LastActivityDate="2016-06-21T18:31:07.497" Title="How can I go from a CPL to an A320 Rating?" Tags="&lt;airbus-a320&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27875" PostTypeId="2" ParentId="27874" CreationDate="2016-05-28T23:33:02.717" Score="1" Body="&lt;p&gt;A U.S. pilot with a Commercial license can get a type rating by going through an appropriate course. It isn't cheap, but it can be done.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefit of having the type rating with only 300 hours is probably pretty slight, at least in the U.S.  Anybody hiring into the right seat of an A320 either has their own &quot;ab initio&quot; curriculum, or else they're probably looking for far more experience than that.  There may be a unique job out there that is looking for exactly this sort of applicant, but it seems hard to imagine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You might be better off saving the money until you have a line on exactly what position you're after, and you're confident that they'd hire you with 300 hours (or whatever you have by then). Who knows -- you may find someplace that will be glad to hire you to fly something else, if you'll get the training on (whatever they fly) by going to get the type rating. Having the money available to spend on the &lt;em&gt;needed&lt;/em&gt; type rating could be a lot more useful than have the 320 type at that point.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-28T23:33:02.717" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27877" PostTypeId="1" CreationDate="2016-05-29T05:26:12.733" Score="2" ViewCount="1609" Body="&lt;p&gt;I know that in the US there exist documents which are published by the FAA such as the Aeronautical Information Manual (AIM) and the Aeronautical Information Publication (AIP). What is the difference of each one? What is their relationship with the Aeronautical Information Service (AIS)?&lt;/p&gt;&#xA;" OwnerUserId="14891" LastActivityDate="2016-11-26T03:56:28.910" Title="What is the difference between AIM, AIP and AIS in the US?" Tags="&lt;aim&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27878" PostTypeId="2" ParentId="27873" CreationDate="2016-05-29T06:25:32.983" Score="4" Body="&lt;p&gt;I read the FARs for this one, and there is a rule:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=912310b5802d43b7d1e6291bfc7340e2&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.5.5.1.2&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR §67.403 Applications, certificates, logbooks, reports, and records: Falsification, reproduction, or alteration; incorrect statements.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;From what I gather, the rule is there to get liars in trouble.&lt;/p&gt;&#xA;&lt;p&gt;If you didn't lie, which you clearly have no reason to because your age does not disqualify you, I don't think you have to worry about getting in trouble because it was the doctor's mistake.&lt;/p&gt;&#xA;&lt;p&gt;However: (&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=912310b5802d43b7d1e6291bfc7340e2&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.5.5.1.2&amp;amp;idno=14&quot; rel=&quot;nofollow noreferrer&quot;&gt;From 67.403&lt;/a&gt;)&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;(c) The following may serve as a basis for suspending or revoking a&#xA;medical certificate; withdrawing an Authorization or SODA; or denying&#xA;an application for a medical certificate or request for an&#xA;authorization or SODA:&lt;/p&gt;&#xA;&lt;p&gt;(2) &lt;strong&gt;An incorrect entry&lt;/strong&gt;, upon which the FAA relied, &lt;strong&gt;made in any&#xA;logbook, record, or report that is kept, made, or used to show&#xA;compliance with any requirement for a medical certificate&lt;/strong&gt; or an&#xA;Authorization or SODA. [My emphasis]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Let's pull out the important words and we get this:&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;An incorrect entry ... made in any ... record, or report that is &lt;strong&gt;kept ... or used&lt;/strong&gt; to show compliance with any requirement for a medical certificate...&amp;quot;&lt;/p&gt;&#xA;&lt;p&gt;A medical certificate is certainly &lt;strong&gt;kept or used to show compliance&lt;/strong&gt; with a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=daa7831942ba4a74cd7aa2560eeafb51&amp;amp;mc=true&amp;amp;node=se14.2.61_13&amp;amp;rgn=div8&quot; rel=&quot;nofollow noreferrer&quot;&gt;requirement to posses a medical certificate &lt;strong&gt;§61.3(c)(1)&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;You have discovered an incorrect entry.  Call the doctor that issued your medical as soon as you can in order to get it resolved, and do not accept a solo sign-off on this incorrectly filed document now that you have knowledge of the mistake.&lt;/p&gt;&#xA;&lt;p&gt;To give you a straight answer based on my interpretation of the law, &lt;strong&gt;yes; this error would prohibit you from soloing until it can be corrected.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-29T06:33:58.653" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27879" PostTypeId="1" CreationDate="2016-05-29T07:38:29.010" Score="7" ViewCount="3537" Body="&lt;p&gt;I noticed the term BUS in the startup procedure of a 737. What do BUS on, off and transfer mean and what is their significance?&lt;/p&gt;&#xA;" OwnerUserId="8346" LastEditorUserId="3201" LastEditDate="2016-05-29T08:33:08.217" LastActivityDate="2016-05-31T08:51:10.470" Title="What does BUS mean in the startup procedure?" Tags="&lt;boeing-737&gt;&lt;electrical-system&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27880" PostTypeId="1" CreationDate="2016-05-29T11:07:59.647" Score="6" ViewCount="884" Body="&lt;p&gt;Raymer says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Landing distance is largely determined by wing loading. Wing loading affects the approach speed, which must be a certain multiple of stall speed (1.3 for civil aircraft, 1.2 for military aircraft). Approach speed determines the touchdown speed, which in turn defines the kinetic energy which must be dissipated to bring the aircraft to a halt. The kinetic energy, and hence the stopping distance, varies as the square of the touchdown speed. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My question is : In which manner does wing loading affect approach speed? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'll explain my question better:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;The first option:&lt;br&gt;&#xA;Higher wing loading implies less wing surface. Therefore, you have a higher value of stall speed (because, for the same lift needed and the same C&lt;sub&gt;L&lt;/sub&gt; and the same density, with a small wing surface area, you have to increase speed to compensate for less surface), so you need a higher value of approach speed. &#xA;In this case : a higher wing loading REQUIRES a higher approach speed.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;The second option:&lt;br&gt;&#xA;Higher wing loading causes less wing surface. Therefore, you have less exposed surface, so you have less drag, so it’s easier to maintain a higher speed.&#xA;So if this last sentence is correct (I’m not sure), in this case it’s not only the required speed, but the CAUSED speed. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;What do you think?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;SOURCE:   DANIEL P: RAYMER “Aircraft Design: A Conceptual Approach”, Chapter 5 “THRUST-TO-WEIGHT RATIO AND WING LOADING”, Paragraph 5.3 WING LOADING, Subparagraph: “Landing distance”&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="13498" LastEditorUserId="21091" LastEditDate="2019-08-15T02:07:16.227" LastActivityDate="2019-08-15T06:12:10.800" Title="Does a high &quot;wing loading&quot; require a high approach speed or does it cause a high approach speed?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27881" PostTypeId="2" ParentId="27880" CreationDate="2016-05-29T11:49:51.703" Score="11" Body="&lt;p&gt;It's the first of your options.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The effect of reduced drag with reduced wing area is dominant only at high speed, when friction drag is dominant. At low speed induced drag is the major source of drag, and with a given planform a smaller wing will create more drag at the same speed, not less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to the possibility of wind shear or gusts you should keep some margin to your stall speed during approach, right down to the flare. Therefore, the safe approach speed dominates the landing distance, as Raymer writes.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-05-29T11:49:51.703" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27883" PostTypeId="1" AcceptedAnswerId="27884" CreationDate="2016-05-29T15:32:21.803" Score="7" ViewCount="1009" Body="&lt;p&gt;In this blog, the FA refers to the 787 Dreamliner as having &quot;lower pressurization&quot;:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://theflightattendantlife.com/the-boeing-787-8-a-flight-attendant-takes-you-on-an-inside-tour-of-the-dreamliner/&quot;&gt;http://theflightattendantlife.com/the-boeing-787-8-a-flight-attendant-takes-you-on-an-inside-tour-of-the-dreamliner/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Dreamliner has higher air-pressure in the cabin due to its fuselage construction -- but this &lt;strong&gt;higher&lt;/strong&gt; air-pressure makes the perceived 'altitude' &lt;strong&gt;lower&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is the correct (air transport) term for this &quot;lower pressurization&quot; or &quot;higher pressurization&quot; or is there a better third alternative??&lt;/p&gt;&#xA;" OwnerUserId="2407" LastEditorUserId="2407" LastEditDate="2016-05-29T15:38:50.257" LastActivityDate="2016-05-29T15:45:06.123" Title="Is &quot;lower pressurization&quot; the correct term for the 787 Dreamliner?" Tags="&lt;terminology&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27884" PostTypeId="2" ParentId="27883" CreationDate="2016-05-29T15:45:06.123" Score="11" Body="&lt;p&gt;The terminology is confusing. When you say lower or higher, it is better to clarify the reference. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing 787 has a &lt;a href=&quot;https://aviation.stackexchange.com/questions/1728/does-the-b787-dreamliner-operate-with-higher-cabin-pressure&quot;&gt;&lt;em&gt;higher cabin pressure&lt;/em&gt;&lt;/a&gt; compared to the legacy airliners.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The best way to say it is that it is pressurized to (or has) a lower cabin altitude compared to other airliners.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-05-29T15:45:06.123" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27885" PostTypeId="1" AcceptedAnswerId="27889" CreationDate="2016-05-29T15:45:09.130" Score="9" ViewCount="2933" Body="&lt;p&gt;If I were standing outside on a windy day holding a flat rectangular object such as a food tray up in the wind, orthogonal to the direction of flow, the drag created would be classified, mostly, as form drag; a differential in pressure from the higher pressure upwind side of the tray and its lower pressure downwind side.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an airplane's wing began at a 0 degree angle of attack and were slowly rotated to a 90 degree angle of attack, lift would increase until the critical angle of attack is exceeded, but the coefficient of drag would continue to increase up to 90 degrees.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I assume the drag created by the wing at 90 degrees is much like the form drag created by the tray in the wind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is induced drag nothing more than form drag with a different classification due to its usual nature of discussion in regards to lift?&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-07-01T21:32:23.397" LastActivityDate="2020-04-16T08:18:31.967" Title="Is induced drag essentially nothing more than a specific type of form drag?" Tags="&lt;aerodynamics&gt;&lt;drag&gt;&lt;terminology&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27887" PostTypeId="1" CreationDate="2016-05-29T19:02:40.280" Score="3" ViewCount="855" Body="&lt;p&gt;Let's think about a turboprop with a single shaft. The turbine moves the compressor and the propeller.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question: what is the &quot;limit&quot; to the expansion ratio achieved by the turbine?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we call $5$ the air that is exiting the turbine, and $4$ the air that enters the turbine, then the expansion (or compression) ratio is defined by: $$\pi_t\equiv \dfrac{p_{05}}{p_{04}}&amp;lt;0\Longleftarrow \left(\textit{Because air is expanding}\right)$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But for a non-ideal, single-stage axial turbine this ratio can be related to $T_{04}$ (that is, the temperature at the burner exit) by: $$\pi_t=\bigg[1-\dfrac{W_t}{c_p\eta_tT_{04}}\bigg]^{\gamma/\left(\gamma-1\right)}\quad \text{where}\quad \gamma\approx 1,35&amp;gt;0$$ where $W_t$ is the specific energy extracted from the fluid by the turbine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the one hand, as $T_{04}$ increases, $\pi_t$ will increase as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But on the other hand, &lt;em&gt;I think we are interested in $T_{04}$ as high as possible&lt;/em&gt; &lt;strong&gt;BUT&lt;/strong&gt; &lt;em&gt;$\pi_t$ as low as possible&lt;/em&gt;, which comes into direct contradiction right? &lt;em&gt;(Please, correct me here if I'm wrong)&lt;/em&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the compromise solution between $T_{04}$ and $\pi_t$? If we make $T_{04}$ too high (which is thermodinamically convenient) then $\pi_t$ will be higher than its optimal value, and the other way around.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$T_{04}$ has itself a structural/thermal limit (if it goes too high, it can ultimately melt and/or generate way too high pressure on the turbine blades until it breaks). I think this defines a maximum value for $\pi_t$, right? Although knowing the maximum $\pi_t$ I think doesn't make sense, because we want to minimize it.&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="7990" LastEditDate="2016-05-29T19:10:48.327" LastActivityDate="2016-05-29T19:10:48.327" Title="Maximum/Lowest achievable expansion ratio (generally) in a turbine?" Tags="&lt;engine&gt;&lt;turbine&gt;&lt;aerospace-materials&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-06-09T12:15:25.827" ContentLicense="CC BY-SA 3.0" />
  <row Id="27889" PostTypeId="2" ParentId="27885" CreationDate="2016-05-29T22:28:13.643" Score="20" Body="&lt;h1&gt;No, &lt;em&gt;by definition&lt;/em&gt; it isn't.&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;There is drag. Drag is caused by different physical phenomena. According to the cause, it is classified to:&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Induced drag&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Induced drag is side-effect of &lt;em&gt;generating lift&lt;/em&gt; over finite wing span.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lift is an upward force that the air exerts on the wing. By principle of action and reaction (Newton's third law of motion), the wing exerts downward force of equal magnitude on the air, and since the air is free to move, that force accelerates the air downwards.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now there are two equivalent arguments why this causes drag:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;In the frame of reference of the wing, the wing is not doing any work (because it is not moving), so it can't change kinetic energy of the air, and therefore can't change its total velocity. Since the vertical component of that velocity increases, the horizontal component has to decrease and this requires forward force from the wing. The backward reaction to that force is the induced drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In the frame of reference of the oncoming air, the kinetic energy does increase. Therefore the wing has to do some work on the air, which means applying force in direction of its motion. The backward reaction to that force is the induced drag.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The explanations are both equally true, just using different frame of reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Induced drag &lt;em&gt;decreases&lt;/em&gt; with (square of) speed (for constant lift), because at higher speed there is more air to accelerate, so it only needs to be accelerated by less.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Induced drag is also &lt;em&gt;independent of cross-section&lt;/em&gt;. If you cancel lift by moving elevator or aileron up, the cross-section may not change at all (the flap might still be behind the wing), but the induced drag will vanish.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By the way, it follows from this that induced drag of wing at 90 degrees is zero, because it is not producing any lift. The form drag is, of course, huge.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Form drag&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Form drag is caused by imperfect pressure recovery behind the body. At the front of the object moving through fluid the fluid slows down, which comes with increase of pressure. In ideal laminar flow the fluid closes behind the object with the same slow speed and same high pressure. But as the object moves faster, the inertia causes the flow to separate and form a turbulent area behind the object where the pressure remains low. This pressure difference cause the form drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The form drag depends on cross-section and shape of the object. It always increases with speed.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Interference drag&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;When complex structure, like an aircraft, is analysed, the form drag of each component (wing, fuselage, empennage etc.) is first analysed independently. But as the components are assembled together, the pressure fields around the parts negatively affect each other and this increase in drag is then called interference drag.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Skin drag&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Skin drag is caused by the friction between the surface of the object and the fluid. The skin drag depends mainly on &lt;em&gt;wetted surface&lt;/em&gt; of the object. It increases with speed in similar way to the form drag, so for practical purposes it is usually combined with the form drag into one term, the &lt;a href=&quot;https://en.wikipedia.org/wiki/Parasitic_drag&quot; rel=&quot;noreferrer&quot;&gt;parasitic drag&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Wave drag&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;As the object moving through fluid approaches the speed of sound, the flow exceeds it as it tries to avoid the object and forms a shock wave. Behind the shock wave the pressure is much higher and this increase is not balanced by any increase on the aft part of the object, therefore causing large amount of drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This kind of drag only appears as the flow speed approaches speed of sound, but then it quickly grows larger than the other forms.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-06-30T05:04:20.760" LastActivityDate="2016-06-30T05:04:20.760" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="27890" PostTypeId="2" ParentId="27877" CreationDate="2016-05-30T00:37:30.533" Score="3" Body="&lt;p&gt;From the beginning section of the Aeronautical Information Manual (AIM).&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;This manual is designed to provide the aviation community with basic flight information and ATC procedures for use in the National Airspace System (NAS) of the United States. An international version called the Aeronautical Information Publication contains parallel information, as well as specific information on the international airports for use by the international community.&lt;/p&gt;&#xA;&lt;p&gt;This manual contains the fundamentals required in order to fly in the United States NAS. It also contains items of interest to pilots concerning health and medical facts, factors affecting flight safety, a pilot/controller glossary of terms used in the ATC System, and information on safety, accident, and hazard reporting.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;Aeronautical Information Publication&lt;/strong&gt; front section&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;2.1 The AIP is prepared in accordance with the Standards and Recommended Practices (SARP) of Annex 15 to the Convention on International Civil Aviation and the Aeronautical Information Services Manual (ICAO Doc 8126). Charts contained in the AIP are produced in accordance with Annex 4 to the Convention on International Civil Aviation and the Aeronautical Chart Manual (ICAO Doc 8697). Differences from ICAO Standards, Recommended Practices and Procedures are given in subsection GEN 1.7.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/flight_info/aeronav/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aeronautical Information Services&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Is the authoritative government source for collecting, validating,&#xA;storing, maintaining, and disseminating aeronautical data for the U.&#xA;S. and its territories.&lt;/li&gt;&#xA;&lt;li&gt;Develops and maintains all public instrument flight procedures and airways.&lt;/li&gt;&#xA;&lt;li&gt;Serves as the FAA's aeronautical charting authority for the development, publication, and dissemination of aeronautical charts and products to support aviation and to meet demand for increased capacity, efficiency, and predictability in the airspace, routes, and airports of the NAS.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-05-30T00:37:30.533" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27891" PostTypeId="2" ParentId="14705" CreationDate="2016-05-30T01:02:35.453" Score="12" Body="&lt;p&gt;It has nothing to do with cost or wasting fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A military jet is notoriously designed to do the best it can, to hell with how much it costs.&#xA;If expense of construction was a concern, they'd think it was ridiculous to build from exotic components just to shave a few pounds. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fuel efficiency and fuel cost is only a concern in terms of being economical as possible in order to have the best range to attack the enemy, or to loiter on station on patrol. Wasting a little fuel on landing is inconsequential; why else would jet fighters have fuel dumps? It's common to jettison any few thousand extra pounds of fuel to get landing weight down, and it's also common to take extra fuel on from the tanker just in case. So you take three times as much fuel as you need to get back to base, then when you get there safely, you just dump it so you're light enough to land.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;They don't include reversers because the extra weight and space they need would be better used for something else like fuel or avionics.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military jets, especially fighters, are ridiculously expensive to operate, not just buy. Commercial aircraft, on the other hand, need to do things cheaply, with little maintenance and short turn-around times. Passenger aircraft and airlifters are far larger and heavier than fighters; that's why they need reverse thrust. A big enough parachute is a real pain to pack back up again, and replacing worn out brakes is expensive. A thrust reverser is extra initial expense, but it pays for itself.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Military &lt;em&gt;large airlifters&lt;/em&gt; use thrust reversers to quickly unload and return for more, and to land on short runways; that's rarely a concern for a fighter. They may also need to turn themselves around for takeoff; while a fighter could be pushed by hand in a pinch, a C-5 Galaxy, not so easy. It's not surprising, in the few fighters that have a reverser (the Tornado and the Saab Viggen), landing on short or icy runways was a primary motivation, coupled with rapid turnaround, and the fact that parachutes are only effective at high speeds.&lt;/p&gt;&#xA;" OwnerUserId="15165" LastEditorUserId="31425" LastEditDate="2019-10-25T04:19:50.597" LastActivityDate="2019-10-25T04:19:50.597" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="27892" PostTypeId="2" ParentId="27802" CreationDate="2016-05-30T04:36:09.607" Score="1" Body="&lt;p&gt;After the collapse of the USSR and break-up of Aeroflot into smaller regional entities, there was (reportedly) a widespread practice of such incentives. Or rather, disincentives to 'waste' fuel. Say, a pilot could be penalised for doing such 'unnecessary' thing as a go-around. This was often unofficial or semi-official, but still put pressure on pilots to compromise safety. It is believed such practice may have contributed to some accidents in the 90s.&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-05-30T04:36:09.607" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27893" PostTypeId="2" ParentId="27879" CreationDate="2016-05-30T07:11:42.897" Score="11" Body="&lt;p&gt;A bus is a strong connection that distributes current. It's not limited to the conductive part, it is usually understood as including the switches and relays that manage its connection to the rest of the wiring.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(Keep in mind that with AC, when two different sources are used to feed the same component, &lt;a href=&quot;http://electrical-engineering-portal.com/preparing-to-synchronize-a-generator-to-the-grid&quot; rel=&quot;noreferrer&quot;&gt;frequency and phase&lt;/a&gt; need to be adjusted and must coincide, else energy would be lost, and voltage increased / decreased, possibly to a dangerous level.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The transfer buses in that case have a logic detecting multiple current sources, e.g. battery and ground supply, and selecting which one to use to feed the bus. The crew has some authority on this process, using switches:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RYsir.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RYsir.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.b737.org.uk/electrics.htm&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is one transfer bus on each side of the aircraft. They feed other buses, like galley and main buses, with energy, typically from the engine generators. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are connected by the tie bus (between BTB1 and 2 on the image, it's name doesn't appear), for redundancy purposes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/18pHc.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/18pHc.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Boeing 737 NG, modified (&lt;a href=&quot;http://virtualairlines.hu/737NG_Videok/737NG_04_ELECTRICAL.pdf&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before the two engines are running (and their generator supplies current), the tie bus allows the ground power, or the APU, or a single engine to feed the whole aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Transfer buses can be disconnected from the tie bus for normal use, each engine generator providing energy to different smaller buses, creating a redundancy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If one source fails, the other can feed the whole aircraft by connecting the tie bus. Another connection can be used on the DC part (cross-bus tie relay). This mode is useful and required when performing an approach with the autopilot (e.g. ILS cat III).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Conversely if one transfer bus creates a security problem, it can be switched off.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-05-31T08:51:10.470" LastActivityDate="2016-05-31T08:51:10.470" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27894" PostTypeId="2" ParentId="27865" CreationDate="2016-05-30T08:33:32.697" Score="1" Body="&lt;p&gt;To add to Greg's answer (which points to the two most obvious suspects), I'd say that a typical stable canard should have a higher incidence on the canard than on the wing. You can offset it with a constant pitch up trim, but apparently you don't have enough of it (for the chosen CG position).&lt;/p&gt;&#xA;" OwnerUserId="13666" LastActivityDate="2016-05-30T08:33:32.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27895" PostTypeId="1" CreationDate="2016-05-30T09:14:14.287" Score="8" ViewCount="2255" Body="&lt;p&gt;What are the operational differences between normal diesel fuel used in cars and the Jet-A diesel type fuel used for some prop aircraft such as the Diamond DA62? I know that aircraft use Jet-A fuel, but could an airplane be run on car diesel?&lt;/p&gt;&#xA;" OwnerUserId="15172" LastEditorUserId="12720" LastEditDate="2016-05-31T10:41:54.323" LastActivityDate="2018-08-09T13:59:58.567" Title="Can a Diesel Aircraft engine be run on Car Diesel?" Tags="&lt;fuel&gt;" AnswerCount="3" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27896" PostTypeId="1" AcceptedAnswerId="27903" CreationDate="2016-05-30T10:21:09.500" Score="5" ViewCount="1531" Body="&lt;p&gt;What happens in a commercial airliner, when a passenger finds the seat belt to be broken. Does the crew de-plane the passenger or do they provide him something like a child/infant seat belt?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm also curious as to FAA's regulation on this area, if any.&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="7532" LastEditDate="2016-05-30T14:41:55.677" LastActivityDate="2016-05-30T14:41:55.677" Title="What happens if a seat belt is found broken, before flight take off?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;passenger&gt;&lt;seats&gt;" AnswerCount="1" CommentCount="8" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27897" PostTypeId="1" AcceptedAnswerId="27898" CreationDate="2016-05-30T10:31:58.787" Score="2" ViewCount="294" Body="&lt;p&gt;Is it possible to download the flight route before the flight?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in a table (or something similar) containing the following data:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;Timestamp | Coordinates | Human readable location&#xA;————————-—+————————————-+—————————————————————————&#xA;                       ...&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;This would be quite helpful, so I can follow the airplane progress during the flight, without having internet connection.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Where can I get that from?&lt;/p&gt;&#xA;" OwnerUserId="15173" LastEditorUserId="1467" LastEditDate="2016-05-30T10:50:51.037" LastActivityDate="2016-05-30T13:09:51.403" Title="Where to download a specific flight route before the flight?" Tags="&lt;commercial-aviation&gt;&lt;flight-path&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27898" PostTypeId="2" ParentId="27897" CreationDate="2016-05-30T11:23:20.170" Score="2" Body="&lt;p&gt;From what I know, you can &quot;decode&quot; certain routes on flightaware.com which will bring up this which may be the closest thing possible to what you want.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gJ1GA.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gJ1GA.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-05-30T11:23:20.170" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27899" PostTypeId="2" ParentId="27897" CreationDate="2016-05-30T13:09:51.403" Score="1" Body="&lt;p&gt;No, such information is not publically available.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It does exist, of course, but in order to obtain it, you would have to know a dispatcher or something similar, and they would have to be willing to disregard their confidentiality agreement.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You could always find the specific flight (flown on a previous date) in a website such as FlightAware of FlightRadar24, and see which route it flew. The route will likely be similar, but not necessarily the same.&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-05-30T13:09:51.403" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27900" PostTypeId="1" CreationDate="2016-05-30T13:40:00.330" Score="2" ViewCount="49" Body="&lt;p&gt;So I have an interesting scenario:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You hold an ASEL private pilot certificate in the USA with high-performance and complex endorsements. You also fly a Cessna 206 on a regular basis.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that all your certs and currencies are valid, are you allowed to act as the sole PIC of a Cessna 206 amphibian as long as you perform your takeoffs and landings on land only?&lt;/p&gt;&#xA;" OwnerUserId="15104" LastEditorUserId="62" LastEditDate="2016-05-30T15:19:19.350" LastActivityDate="2016-05-30T15:19:19.350" Title="Flying an amphibian with ASEL privileges" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;amphibian&gt;" AnswerCount="0" CommentCount="0" ClosedDate="2016-05-30T16:32:08.957" ContentLicense="CC BY-SA 3.0" />
  <row Id="27902" PostTypeId="2" ParentId="27833" CreationDate="2016-05-30T14:35:54.667" Score="7" Body="&lt;p&gt;The commercial aviation world today emphasizes crew resource management (CRM) as an integral part of flying. The premise of effective CRM lies in the principle that any member of the flight crew, whether it's the captain or the first officer, is able to, and should express honest and valid concerns during the flight without worrying about being marginalized or ignored.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Before I start, I would like to point out that Asian airlines are not the only ones to exhibit poor crew management in the past. &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow noreferrer&quot;&gt;KLM 4805&lt;/a&gt; (Tenerife), &lt;a href=&quot;https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eastern 401&lt;/a&gt; (crew gets distracted on approach trying to replace a light bulb), and more recently, &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_447&quot; rel=&quot;nofollow noreferrer&quot;&gt;Air France 447&lt;/a&gt; serve as some examples.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think the reason why crew management-related accidents in Asia come under the spotlight much more than others (I still hear &lt;a href=&quot;https://en.wikipedia.org/wiki/Asiana_Airlines_Flight_214&quot; rel=&quot;nofollow noreferrer&quot;&gt;Asiana 214&lt;/a&gt; jokes all the time, and it's getting really old...) is the fact that the very nature of East Asian culture counters the basic premise of effective CRM — that regardless of position or status in the cockpit, each crew member has a responsibility and a right to speak up. Instead, everybody has a clear-cut hierarchical position roughly based on age. Therefore, whereas accidents in the West are viewed as one-off mistakes made by individuals in an individual case, accidents in the East are viewed more as a natural consequence of the area's culture.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, Asian aviation has changed a lot since the '80s. CRM training is a big thing in the industry (just like how the western world has been doing it) and there has been a giant push in the general culture as a whole to create an environment where everyone is heard with equal weight. Change alright, but the roots of old culture remain despite these recent developments, and this is especially true in the corporate environment (including the cockpit). The give-it-to-me-straight-doc cockpit culture in the East still makes it very hard for the FO to speak up and sort of awkward for the captain to allow other crew members to cooperate, even if he or she is willing to make the most use of the crew body.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, to wrap up my answer to the question, there have been numerous efforts to improve crew management/human factors in the East, but we haven't quite seen the full effects of such changes. Perhaps when the current generation of pilots go (most of them in their '40s and '50s, who were born before the rapid cultural changes in Asia) and the newer, younger generation sets in might we be able to better gage the true effects of changing culture in Asia.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There is no way to summarize this entire subject in a perfectly objective way and there will be people that disagree with some things I've noted. All my above observations were made as a Korean now living in the US. Hopefully my 2 cents help.&lt;/p&gt;&#xA;" OwnerUserId="15104" LastEditorUserId="2556" LastEditDate="2018-10-02T13:47:53.143" LastActivityDate="2018-10-02T13:47:53.143" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27903" PostTypeId="2" ParentId="27896" CreationDate="2016-05-30T14:38:12.750" Score="7" Body="&lt;p&gt;Options would be to either move the passenger to another seat &amp;amp; placard that seat as unusable, or go back to the gate and have maintenance fix what's broken. In the former case, the seat would most likely be fixed by a mechanic at the next station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The seatbelts used in the F/A demos are seatbelt &lt;em&gt;extensions&lt;/em&gt;, which still need the installed seatbelt itself to be intact. They are fully functional as such, though, unlike the demo life vests &amp;amp; O2 masks, which indeed are &quot;demo only&quot; and of no use at all in a real emergency.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a mechanic, the seatbelt is quick &amp;amp; easy to replace, although without needle-nose pliers (and a spare male or female belt), rather difficult for the crew -- who wouldn't be allowed to anyway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA requires that every passenger has a seatbelt and has been told how &amp;amp; when to use it, and that the crew has verified that they have it on before takeoff.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-30T14:38:12.750" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27906" PostTypeId="2" ParentId="25245" CreationDate="2016-05-30T22:28:06.033" Score="6" Body="&lt;p&gt;At full power it is the mixing process of the fast exhaust flow with the surrounding air. Note that noise increases with the sixth to eighth power of jet velocity, so the loudest engines are those with a low bypass ratio  and reheat on.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/Rp90i.gif&quot; alt=&quot;Plot of exhaust noise level over jet velocity&quot;&gt;&#xA;Diagram from a &lt;a href=&quot;http://adg.stanford.edu/aa241/noise/noise.html&quot; rel=&quot;noreferrer&quot;&gt;Stanford web page on noise&lt;/a&gt;. The jet velocity is in ft/s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At idle the biggest noise source of the whole aircraft is the flow around the lowered landing gear, gear cavities and the slotted flaps that you asked us to disregard. The engine noise is a combination of intake noise, bearing noise and nozzle noise, and which of those contributes most to the engine noise depends on the individual engine and its installation into the aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-05-30T22:28:06.033" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27908" PostTypeId="2" ParentId="27848" CreationDate="2016-05-31T00:48:43.407" Score="14" Body="&lt;p&gt;The answer to your question is actually really simple: do not exceed the limitations specified in the POH.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Really, that's it!  Note that &lt;em&gt;LIMITATIONS&lt;/em&gt; are not the same as &lt;em&gt;RECOMMENDED PROCEDURES.&lt;/em&gt;  Recommended procedures are just that: recommendations.  Limitations (exclusively from the &quot;limitations&quot; section of the POH) are the hard and fast rules you must adhere to.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Full RPM in Cruise&lt;/strong&gt;&lt;br&gt;&#xA;As long as your POH does not impose a limitation on takeoff RPM (the Seneca II has such a limitation, for example), then there is nothing wrong with using max RPM from takeoff to shutdown. You won't damage the engine.  If the POH provides a limitation on engine RPM (specifically in Section II of the POH), you must adhere to that limitation.  It's common to see a 5 minute &quot;max RPM&quot; limitation on some turbocharged engines.  Great, takeoff at max RPM then pull the engines back to the top of the green arc until you land.  Easy! &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Manifold Pressure &amp;amp; RPM&lt;/strong&gt;&lt;br&gt;&#xA;Mike Sowsun said:&#xA;&quot;You should always follow the manufacturer's procedures &lt;em&gt;but a general rule for direct drive normally aspirated engines is to keep the manifold pressure less than the RPM for cruise power. (eg. 24 inches of MP at 2400 RPM).&lt;/em&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you decide to apply &quot;rules of thumb&quot; to all phases of flight you will be voluntarily handicapping your airplane's full potential.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some definitions:&lt;br&gt;&#xA;Oversquare - manifold pressure &gt; RPM (23&quot; @ 2100 RPM)&lt;br&gt;&#xA;Undersquare - manifold pressure &amp;lt; RPM (23&quot; @ 2500 RPM)&lt;br&gt;&#xA;Square - manifold pressure = RPM (23&quot; @ 2300 RPM)&lt;br&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do not embrace the idea that manifold pressure should never, ever exceed the value of the first two digits of the engine RPM (sounds pretty arbitrary when I put it that way, right?).  It actually may be beneficial to run an engine &quot;oversquare&quot; in some cases!  This is another example of why knowing your aircraft's &quot;Section II&quot; limitations is important.  If 23&quot; @ 2100 RPM falls within the limitations, go for it!!  You won't hurt the engine.  Same with 25&quot; @ 2300 RPM or 26.756431&quot; @ 2196.454634 RPM.  I think you get my drift.  As long as your manifold/RPM combination falls within the limitations set out in Section II of the POH, you're golden!!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, climbing out on a hot day with a garden variety Lycoming or Continental (like in 170)?  29&quot; @ 2100 RPM probably isn't wise.  30&quot; @ 2700 RPM?  Yeah, that's better!  25&quot; @ 2500 RPM isn't bad but it's no better or worse that 26&quot; @ 2700 RPM or 30&quot; @ 2650 RPM.  Remember, there's nothing special about &quot;square&quot; manifold/RPM values.  I'd routinely run the IO-520 in my Bonanza at max manifold pressure and max RPM from takeoff to cruise and simply leaning to an EGT target as I climbed (and watching CHTs, of course).  Only when leveling off in cruise did I pull it back to an economical setting (sometimes oversquare, sometimes undersquare; always lean of peak).  The engine ran beautifully with good CHTs and incurred no unusual wear.  In fact, the engine's health improved.  Exhaust and plugs became noticeably cleaner and compressions improved.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In cruise, set the power to any combination of manifold/RPM you desire &lt;em&gt;provided&lt;/em&gt; that setting falls within the limitations in your POH.  You won't hurt the engine with a valid manifold/RPM setting.  It's possible to put undue stress on a motor with a bad mixture setting, though.  POHs are notorious for giving poor guidance with regard to mixture settings.  Mixture settings require a little more attention above ~65% power but that's another topic entirely.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recommend that everyone with engine questions read John Deakin's &quot;Pelican Perch&quot; articles.  He's THE source for fact based, accurate engine operation information. He happens to have touched on this &quot;oversquare&quot; myth here.  See &lt;a href=&quot;http://www.avweb.com/news/airman/184274-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Myth #2&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: I credited John Deakin with my linked article.  I was mistaken.  The author of the linked article is Linda Pendelton.  She links to a Deakin article, though.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mike Busch also addresses the oversquare myth &lt;a href=&quot;http://www.avweb.com/news/airman/184483-1.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2017-06-29T16:28:08.190" LastActivityDate="2017-06-29T16:28:08.190" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27909" PostTypeId="1" CreationDate="2016-05-31T01:38:13.260" Score="7" ViewCount="815" Body="&lt;p&gt;Dry thrust is normal jet engine power without using an afterburner. Max dry thrust is the engine's most powerful thrust level without afterburner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But what if the engine is at half power, or even idle power? Can you safely engage afterburner at that point?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in turbojets and turbofans. Both can have an afterburner. I'm wondering if it's possible to engage afterburner on both of them at a time when the engine is not already at full dry thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Edit: one reason it might not work is that idle thrust might not be powerful enough to ignite the fuel in the afterburner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I ask is for emergencies. Jet engines need several seconds to spool up from idle to full thrust. If you could engage afterburner from the get-go, you could be up to max speed much quicker.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-06-02T05:31:06.873" LastActivityDate="2016-06-02T05:31:06.873" Title="Will afterburner work at settings less than full dry thrust?" Tags="&lt;jet-engine&gt;&lt;military&gt;&lt;afterburner&gt;" AnswerCount="1" CommentCount="1" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27910" PostTypeId="2" ParentId="27909" CreationDate="2016-05-31T03:10:45.687" Score="9" Body="&lt;p&gt;Afterbuner simply injects fuel directly into the jet pipe (i.e. beyond the turbine) in order to greatly increase thrust. The way throttle levers are normally set up, afterburner is engaged once the lever is advanced past maximum dry thrust, but I can't imagine why, theoretically, you couldn't set one up to be engaged at less than maximum dry thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mind you, it would be awfully inefficient to do so, as thrust output is exponential, with most of it being delivered in the top 5% of the RPM band; engaging afterburner while you still have a lot of dry thrust available would just be a massive waste.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What's more, jet engines are much quicker to respond today, and, in addition, landing approaches are not performed at idle thrust; the main benefit of flap settings greater than 20 degrees is that they slow the aircraft down, allowing for steeper approaches. In jet aircraft, this also allows the engines to be kept spooled up above flight idle, specifically in order to reduce response times in the event of a go around. &#xA;In other words, throttle might be reduced to flight idle for the initial descent, but the final approach will use a higher thrust setting. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The benefits of adding afterburner to civilian transport aircraft are usually massively outweighed by their costs (see the Concorde and Tu-144). &lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2016-05-31T03:10:45.687" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27912" PostTypeId="1" CreationDate="2016-05-31T05:01:18.140" Score="0" ViewCount="139" Body="&lt;p&gt;One thing I have always wondered when taking intercontinental flights is the way passengers are distributed in an aircraft. It seems to me that in some way people of different ethnicities are purposely mixed. I have the strange idea that this is preset and done mostly for security reasons. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Seeking for clarification on this matter. Please do not get me wrong as I am not trying to classify different types of people! &lt;/p&gt;&#xA;" OwnerUserId="770" LastActivityDate="2016-05-31T23:54:43.420" Title="Is seating distribution planned in airliners or is it left to casuality?" Tags="&lt;security&gt;" AnswerCount="1" CommentCount="4" ClosedDate="2016-05-31T11:29:47.020" ContentLicense="CC BY-SA 3.0" />
  <row Id="27913" PostTypeId="2" ParentId="27912" CreationDate="2016-05-31T05:26:59.737" Score="5" Body="&lt;p&gt;People tend to travel by themselves or in small groups. They sit all over the airplane, either selecting their own seats or having them assigned by the airline's ticketing system. When you go to select your seats, the system shows you what seats are available, but it does not show you other passenger's ethnicities. Airlines also don't necessarily know passengers' ethnicities when assigning seats in advance, except to the extent that they could conceivably guess based on names (they may know what country's passport someone is traveling on, which is not the same as their ethnicity, but even so, they may not know this information until well after a seat assignment is in place).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So lots of people check-in and have their seats assigned basically randomly. The expected result is that small groups of people of different ethnicities would be mixed throughout the plane fairly randomly. I'm not understanding why you think this is something an airline would deliberately need to do, as it would already happen naturally. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Using ethnicity for seating purposes could also violate anti-discrimination laws in many countries, if this was something an airline even wanted to do.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is sometimes the case that a large group of passengers largely of the same ethnicity will book a block of seats together as part of a group booking, such as a Japanese school trip or German musicians. Such groups may, if space permits, be seated together, and if the group is relatively ethnically homogeneous, you may find a number of travelers of one ethnicity seated together for this reason.&lt;/p&gt;&#xA;" OwnerUserId="5568" LastEditorUserId="5568" LastEditDate="2016-05-31T23:54:43.420" LastActivityDate="2016-05-31T23:54:43.420" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27916" PostTypeId="1" CreationDate="2016-05-31T11:03:00.030" Score="1" ViewCount="3357" Body="&lt;p&gt;I am trying to figure out how does the horizontal stab attached itself to the plane and moves up and down? Is the HS attached by the rear spar and to the fuselage? &lt;/p&gt;&#xA;" OwnerUserId="15188" LastActivityDate="2016-06-03T02:52:26.713" Title="How is a horizontal stabilizer attached to the fuselage and works as a trimmable Horizontal Tail as well?" Tags="&lt;fuselage&gt;&lt;trim&gt;&lt;horizontal-stabilizer&gt;&lt;plane-construction&gt;" AnswerCount="3" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27917" PostTypeId="2" ParentId="27867" CreationDate="2016-05-31T11:54:16.190" Score="3" Body="&lt;p&gt;A number of experiments and papers by Robert Hoey (from the early 1990s on) have used models of flat-winged soaring birds such as ravens.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of his papers is referenced in this broad review: &lt;a href=&quot;https://lentinklab.stanford.edu/uploads/1354400541_2010%20bioinspired%20flight%20lentink.pdf&quot; rel=&quot;nofollow&quot;&gt;Lentink &amp;amp; Biewener 2010&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of his earlier papers is copied here: &lt;a href=&quot;http://www.johnnyarmstrong.com/wp-content/uploads/2014/03/RavenAIAAcomplete-pdf.pdf&quot; rel=&quot;nofollow&quot;&gt;Hoey, 1992, American Institute of Aeronautics &amp;amp; Astronautics&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The topics include some discussion of low static stability of the model and the lack of vertical surfaces in real birds, as well as unknowns such as wing profile.&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2016-05-31T11:54:16.190" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27918" PostTypeId="1" CreationDate="2016-05-31T15:12:36.003" Score="4" ViewCount="604" Body="&lt;p&gt;How much thrust is involved, and how much fuel is burned, to get an aircraft like a Boeing 767 - or something similar - moving from a complete stop?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recently, I was on a 767 that took the &quot;scenic route&quot; around the &lt;a href=&quot;https://en.wikipedia.org/wiki/Dallas/Fort_Worth_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;DFW airport&lt;/a&gt; trying to get to a gate.  We were on the tarmac for an unusually long time, and had multiple stops and starts.  I was curious how that might have affected fuel costs as opposed to a shorter time on the tarmac and a more direct path to our gate.&lt;/p&gt;&#xA;" OwnerUserId="15189" LastEditorUserId="62" LastEditDate="2016-05-31T15:48:56.730" LastActivityDate="2020-12-30T12:48:06.763" Title="How much thrust and fuel are required to get a B767 moving from a complete stop?" Tags="&lt;fuel&gt;&lt;taxiing&gt;&lt;boeing-767&gt;" AnswerCount="1" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27919" PostTypeId="2" ParentId="27895" CreationDate="2016-05-31T15:42:29.137" Score="8" Body="&lt;p&gt;In at least some cases, yes. &lt;a href=&quot;http://www.continentaldiesel.com/typo3/index.php?id=102&amp;amp;L=1&quot; rel=&quot;noreferrer&quot;&gt;Continental's CD-155 diesel engine&lt;/a&gt; will run on auto diesel, Jet A or any mixture of both:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The CD-155 is certified for the use of both jet fuel and diesel (DIN&#xA;  EN590) and is running with the two fuels in any mixture ratio.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;EN590 is the European &lt;a href=&quot;https://en.wikipedia.org/wiki/EN_590&quot; rel=&quot;noreferrer&quot;&gt;standard for auto diesel&lt;/a&gt;. The &lt;a href=&quot;http://www.geminidiesel.aero/aviation/gemini-125&quot; rel=&quot;noreferrer&quot;&gt;Gemini 125 engine&lt;/a&gt; can run on Jet A and diesel according to their website, as can the &lt;a href=&quot;http://austroengine.at/en/products&quot; rel=&quot;noreferrer&quot;&gt;Austro AE300&lt;/a&gt;. So it seems that in general, aircraft diesel engines can indeed run on auto diesel.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-05-31T15:42:29.137" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27920" PostTypeId="2" ParentId="27918" CreationDate="2016-05-31T16:08:48.430" Score="5" Body="&lt;p&gt;&lt;a href=&quot;http://www.mit.edu/~hamsa/pubs/KhadilkarBalakrishnanGNC2011.pdf&quot; rel=&quot;nofollow&quot;&gt;This research paper&lt;/a&gt; may be of interest for you. According to their data the 777 burns about 250Kg of fuel on taxi on average with a few data points showing burns well over 700Kg of fuel. &lt;a href=&quot;http://apex.aero/wp-content/uploads/2014/11/APEX-Airline-Fuel.pdf&quot; rel=&quot;nofollow&quot;&gt;This paper&lt;/a&gt; which quotes the previously linked paper talks a bit about different fuel saving methods and their impacts, like single engine taxi and what not. In short taxi distance will always burn a bit more fuel, the primary concern is taxing for takeoff (since you don't want to cut into your estimates). Once the plane is back on the ground it becomes less of a safety concern as running out of fuel becomes an inconvenience (that a tug can solve) and less of flight risk.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is an &lt;a href=&quot;http://www.atlanta-airport.com/docs/airport/environmental/appendices/Appendix%20E%20-%20Fuel%20Consumption_Taxi-Stage%20Length.pdf&quot; rel=&quot;nofollow&quot;&gt;interesting paper on fuel burn rates&lt;/a&gt; if you were to extend a runway by 500Ft. They provide data/estimates for many air frames.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-06-01T04:43:44.893" LastActivityDate="2016-06-01T04:43:44.893" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27921" PostTypeId="1" AcceptedAnswerId="27994" CreationDate="2016-05-31T20:02:35.293" Score="10" ViewCount="14514" Body="&lt;p&gt;When commercial airlines calculate the mass and distribution of passenger load, in the cases where they do not weigh the passengers directly, they use standard weight measures which have been approved by the appropriate aviation authority.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard weights can be broken down by passenger type (adult/child), by sex (male/female) and by other factors such as season or business/economy class. To obtain these figures a survey is carried out at an airport and appropriate measures are taken to ensure the sample is representative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The result is a single value that represents the standard weight for a male/female/child/etc. Whilst the standard weight may have a minimal bias (i.e. a small deviation from the population mean), it does not represent the variance of the observed passenger weights. That is if the sample mean is 90kg with a std deviation of 10, the there is a ~15% chance that a passenger has a weight more than 100kg (assuming normal distribution, for the purpose of this example).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Given that airline operators have to be extremely careful and conservative with their weight management how do they account for this uncertainty in their calculations? Using the example above, if there were a flight with 100 passengers each &gt;100kg, there would be an underestimation of mass by over 1 tonne (relatively small in comparison to total loaded aircraft mass, but still a large figure in itself).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Are accommodations for this variation incorporated into the standard passenger weight (say use mean + &lt;em&gt;x&lt;/em&gt; std. dev.) or does this get included in the operational limits that the airline set for their max weight allowances in their various forms, for example reduced Max Zero Fuel Weight (MZFW) or Max Take Off Weight (MTOW)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Edit: This is a slightly different question to a similar one about how a commercial aircraft has its mass determined. The focus here is more specific in looking at how the standard passenger weights are calculated and what are the assumptions around using that data.&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="2280" LastEditorUserId="2280" LastEditDate="2016-05-31T20:44:56.003" LastActivityDate="2016-06-04T19:10:09.113" Title="How do airlines handle uncertainty in passenger weight for weight and balance calculations?" Tags="&lt;weight-and-balance&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27922" PostTypeId="1" CreationDate="2016-05-31T22:00:43.867" Score="14" ViewCount="706" Body="&lt;p&gt;I recently visited Roswell, NM, and was surprised at how many flight tests have been performed there.  Even the fatal Gulfstream flight test crash happened there. My research shows that a lot of flight tests happen at places like San Bernardino, Roswell, Fresno, and  Moses Lake. My research turned up only simplistic explanations for why these airports are so popular like &quot;Boeing chose the San Bernardino facility because of three factors: hangar size, availability and weather.&quot; (Source: &lt;a href=&quot;http://www.sbsun.com/article/ZZ/20130607/NEWS/130609259&quot; rel=&quot;nofollow noreferrer&quot;&gt;The Sun News&lt;/a&gt;)  Is that really all they consider in determining flight test locations?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've heard that you can't do flight tests at just any airport, though I haven't been able to find any relevant legal restrictions.  The airport choice doesn't even seem to be just the obvious factors like weather, runway length, and GA availability.  (I also don't care about specialized testing that would require unusual airports like long runways or specific temperatures.) There are a few dozen low-volume long runways in the arid American West and similar regions.  Why are just a few so popular?  Are there any FAA (or EASA) restrictions on doing flight tests at any old airport?&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="27883" LastEditDate="2018-01-13T14:58:40.050" LastActivityDate="2018-04-05T22:19:38.573" Title="Why are airports like Roswell and Fresno so popular for flight tests?" Tags="&lt;airport&gt;&lt;flight-testing&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27923" PostTypeId="1" AcceptedAnswerId="27925" CreationDate="2016-05-31T22:04:09.457" Score="6" ViewCount="475" Body="&lt;p&gt;I was &lt;a href=&quot;https://aviation.stackexchange.com/questions/16063/solo-under-the-hood&quot;&gt;reading a question about flying under the hood&lt;/a&gt; for Instrument Flight Rules (&lt;a href=&quot;https://en.wikipedia.org/wiki/Instrument_flight_rules&quot;&gt;IFR&lt;/a&gt;) training when this question popped to mind.  Are pilots flying under the hood required to notify the tower?  Does it change the towers approach to that plane at all (especially in &lt;a href=&quot;https://en.wikipedia.org/wiki/Visual_meteorological_conditions&quot;&gt;VMC&lt;/a&gt; conditions)?&lt;/p&gt;&#xA;" OwnerUserId="511" LastActivityDate="2016-05-31T22:25:58.147" Title="Are pilots required to notify the tower when they are flying &quot;under the hood&quot; for IFR training?" Tags="&lt;safety&gt;&lt;air-traffic-control&gt;&lt;flight-training&gt;&lt;instrument-flight-rules&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27925" PostTypeId="2" ParentId="27923" CreationDate="2016-05-31T22:25:58.147" Score="5" Body="&lt;p&gt;No, because the responsibilities aren't any different. And, with a safety pilot on board, the capabilities really shouldn't be either. &lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-05-31T22:25:58.147" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27927" PostTypeId="1" CreationDate="2016-05-31T23:25:43.230" Score="8" ViewCount="965" Body="&lt;p&gt;If we take a single seater electric gyrocopter like &lt;a href=&quot;http://www.auto-gyro.com/chameleon/public/0cf14de7-aaf2-59ef-c3d4-91145c1a49d3/24-06-2015_Press-release_AutoGyro-flies-electric.pdf&quot; rel=&quot;noreferrer&quot;&gt;this one&lt;/a&gt;, could a human-powered propeller &lt;a href=&quot;http://www.wired.com/images_blogs/autopia/2009/12/mozi_011.jpg&quot; rel=&quot;noreferrer&quot;&gt;like this&lt;/a&gt; add to the endurance of the aircraft? The gyrocopter only needs a 32km/h forward speed to stay airborne.&lt;/p&gt;&#xA;" OwnerUserId="1953" LastEditorUserId="22661" LastEditDate="2017-06-25T20:20:07.800" LastActivityDate="2019-10-03T02:26:42.813" Title="How much could human power add to the endurance of an electric gyrocopter?" Tags="&lt;aircraft-performance&gt;&lt;propeller&gt;&lt;experimental-aircraft&gt;&lt;electric-engine&gt;&lt;rotary-wing&gt;" AnswerCount="2" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27928" PostTypeId="2" ParentId="27865" CreationDate="2016-05-31T23:44:13.977" Score="5" Body="&lt;p&gt;My vote is that the surfaces aren't rigid enough and get twisted so much that the control surfaces can't overcome the effect. How floppy (non-rigid) are the wings and the canard surfaces? The wing looks to be sagging under its own weight! My thought too is that you're tail heavy, tail heavy will pitch both ways and you can get stuck in either positive or negative stall (or tuck). Tail heaviness causes the plane to tend towards going or falling flat like a leaf; it's usually strongest (leeast recoverable) when under the influence of negative G's. It doesn't matter whether the craft is upright or inverted; it's still &quot;negative G's&quot; including the caused airflows. Still, my best guess is weak surface rigidity. Good luck with your cool project!!!&lt;/p&gt;&#xA;" OwnerUserId="15168" LastEditorUserId="946" LastEditDate="2016-06-01T18:09:56.033" LastActivityDate="2016-06-01T18:09:56.033" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27929" PostTypeId="2" ParentId="27848" CreationDate="2016-06-01T00:46:14.123" Score="2" Body="&lt;p&gt;I think acpilot covered most of it.  I'd like to add this little tidbit to assist in thinking about how to use your constant speed prop.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A constant speed prop is like a continuously variable transmission.   The main settings to be concerned with are climb and cruise.  In a climb scenario, particularly takeoff, it is desirable to have all power available, this is achieved by running your engine at a higher rpm.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In a cruise scenario, on the other hand, it is desirable to &quot;upshift&quot; by lowering the rpm at a cruise power setting.  This has the effect of opening the pitch of the propeller.  You may find additional efficiency at this setting.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I recommend, and it may exist in your checklist, to move the rpm all the way to the top end as part of your pre-landing checklist.  While the effect on your descent and landing is not of great concern, this simplifies the steps necessary in the event of a go-around.  You are already set up for max power, all that is necessary is to advance the throttle.&lt;/p&gt;&#xA;" OwnerUserId="182" LastActivityDate="2016-06-01T00:46:14.123" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27932" PostTypeId="2" ParentId="27823" CreationDate="2016-06-01T01:30:57.620" Score="0" Body="&lt;p&gt;just thought I would note that I believe torque causes rotation around the longitudinal axis (left wing down)and is corrected with aileron input. P-Factor causes rotation to the left around the vertical axis (yaw) and is corrected with opposite rudder as needed. &lt;/p&gt;&#xA;" OwnerUserId="15197" LastActivityDate="2016-06-01T01:30:57.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27934" PostTypeId="1" CreationDate="2016-06-01T03:30:40.617" Score="1" ViewCount="215" Body="&lt;p&gt;I am interested in the engineering and weights for aircraft around 8,059 lb (3,655 kg) Citation 505) and  18,900 lb (8,570 kg F-16).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Curious about specifically structural mass and landing gear systems. How much can landing gears lift?&lt;/p&gt;&#xA;" OwnerUserId="15196" LastActivityDate="2019-08-14T05:10:01.307" Title="Are there specific mass breakdowns for aircraft?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27935" PostTypeId="2" ParentId="27922" CreationDate="2016-06-01T06:03:02.270" Score="15" Body="&lt;p&gt;You can do flight tests from almost any airport, but it helps if:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;The weather is dry and stable,&lt;/li&gt;&#xA;&lt;li&gt;the field is not too far from the factory,&lt;/li&gt;&#xA;&lt;li&gt;there is a large unpopulated area nearby, and&lt;/li&gt;&#xA;&lt;li&gt;you have support facilities available.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The support facilities were installed by the Air Force, and the other factors were already taken care of by Mother Nature in the case of places like Fresno or Roswell. Given that the distance from Los Angeles, a major aviation industry hub, to Fresno is only a bit more than 200 miles, flight testing in predictable weather and over the open terrain west of Fresno becomes very attractive. If you look at Lancaster, the next town near the vast Edwards Air Force base, the driving distance to Los Angeles is only 70 miles. This should help to explain why Edwards is today the main Air Force test base. Once you have a long runway and some experienced flight test engineers in place, other manufacturers will also converge on this location in order to make their flight testing more predictable and effective.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-06-01T06:03:02.270" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27936" PostTypeId="1" AcceptedAnswerId="27988" CreationDate="2016-06-01T06:09:49.103" Score="1" ViewCount="812" Body="&lt;p&gt;liveatc.net is available, but the voice quality on there, I am given to understand, does not represent the quality of voice available to someone actually sitting in an ATC tower. So I am looking for a source which offers more representative recordings.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;EDIT: I intend to use these recordings to evaluate which speech to text engine &lt;a href=&quot;https://en.wikipedia.org/wiki/List_of_speech_recognition_software&quot; rel=&quot;nofollow&quot;&gt;(Non comprehensive list)&lt;/a&gt; works best in the context of aviation, so recordings which best mirror what happens in reality are important to reduce pre-processing.&lt;/p&gt;&#xA;" OwnerUserId="15201" LastEditorUserId="15201" LastEditDate="2016-06-01T06:57:59.283" LastActivityDate="2016-06-03T10:32:54.960" Title="Are any online resources available for ATC recordings?" Tags="&lt;air-traffic-control&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27937" PostTypeId="2" ParentId="27865" CreationDate="2016-06-01T06:48:05.400" Score="5" Body="&lt;p&gt;Thank you for giving more information, but I still have to resort to speculation. Here are some things you might want to consider:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;A rear-mounted prop stabilizes the aircraft. Full throttle limits your control power. You would had a better chance of recovery with engine idle.&lt;/li&gt;&#xA;&lt;li&gt;No incidence means that the plane needs to compensate for the c.g. location with elevator deflection alone. If your plane is statically stable, it would need to be trimmed with some elevator-down deflection for straight flight. This limits the maximum possible canard lift and your nose-up control power. Better give the canard a few degrees of positive incidence.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;However, from the picture it might well be that you use a full-flying canard. In that case, the incidence is set automatically by trimming, and a nose-up command means increasing the incidence further. Now the control commands do not change the camber of the canard wing which reduces both the amounts of maximum and minimum lift possible. Better use a canard with a stabilizer-elevator combination to increase control power.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You talk of cutting and sanding. Are the wings and canard made from styrofoam? Then @TipStall is right: The plane lacks stiffness. Commanding a descent (what you described as &quot;going down&quot;) increased the dynamic pressure and thus the forces warping wings and canard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For now, I think you suffered a canard wing stall, but I am not able to say why. Either it was aeroelasticity (twisting of wing and canard) or insufficient control power. In that case, use a stabilizer-elevator combination for the canard, throttle your engine and maybe consider a less stable aircraft by shifting the c.g. back a bit.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-06-01T06:48:05.400" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27938" PostTypeId="2" ParentId="27916" CreationDate="2016-06-01T07:02:46.000" Score="2" Body="&lt;p&gt;The stabilizer is hinged at the quarter-chord point of the tail surface and has a second, movable attachment point. This second point can be moved up and down, generally by turning a spindle on which a nut rides which moves the second attachment point.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/MmDvs.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/MmDvs.png&quot; alt=&quot;A340 stabilizer root&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A300 stabilizer root (&lt;a href=&quot;http://www.pprune.org/tech-log/447730-af447-wreckage-found-90.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On this picture (sorry, was the best I could find now) you see the stabilizer being attached to the bulkhead ahead of the APU. Ahead of it, near the left edge of the drawing, you see the vertical spindle which moves the forward attachment point. It turns according to trim commands from the flight control computer or from the cockpit.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastActivityDate="2016-06-01T07:02:46.000" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27939" PostTypeId="1" AcceptedAnswerId="27940" CreationDate="2016-06-01T07:09:22.923" Score="10" ViewCount="4184" Body="&lt;p&gt;I came across the photo below on &lt;a href=&quot;http://flightaware.com/photos/view/6917733-5c59584420ce88b0d0c06a5de54ae9fc587d0e96/staffpicksweek/sort/date/page/1&quot; rel=&quot;noreferrer&quot;&gt;flightaware.com&lt;/a&gt;. The image was taken by someone with, I think, an Ukrainian name: Arkadiusz Cieslak. They piqued my interest as they do not appear to have insignia except for the &quot;B&quot; (cyrillic?) on the tail of the transport plane and a design on the fighters. Any ideas? I'm just curious.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/QcaAW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/QcaAW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2550" LastEditorUserId="1696" LastEditDate="2016-06-01T19:54:13.913" LastActivityDate="2016-09-22T15:50:43.113" Title="What are these small jets and large propeller aircraft flying in formation?" Tags="&lt;aircraft-identification&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27940" PostTypeId="2" ParentId="27939" CreationDate="2016-06-01T07:14:09.573" Score="22" Body="&lt;p&gt;The design on the belly of the fighters makes it clear that they are from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Patrouille_Suisse&quot;&gt;Patrouille Suisse&lt;/a&gt;, the aerobatic team of Switzerland. They use &lt;a href=&quot;https://en.wikipedia.org/wiki/F-5_Freedom_Fighter&quot;&gt;F-5E&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the comment in the page you linked (or from the aircraft registration HB-RSC, as suggested by @falstro), instead, we see that the other aircraft is the Breitling (hence the &quot;B&quot;) &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_Constellation&quot;&gt;Super Constellation&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Breitling Super Constellation from the Swiss Super Constellation Flyers Association: It is the last Super Constellation in flying condition in Europe.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="1467" LastEditDate="2016-06-01T07:20:35.153" LastActivityDate="2016-06-01T07:20:35.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27941" PostTypeId="2" ParentId="27916" CreationDate="2016-06-01T09:42:20.580" Score="3" Body="&lt;p&gt;Fighter aircraft usually have their tailplane connected to the fuselage with a single pivot joint, as visible in this F-15 drawing:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cc6bR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cc6bR.jpg&quot; alt=&quot;F-15 stabilator&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Passenger aircraft often have a horizontal tailplane which is a single part, and as such, the entire stabilizer is being trimmed by an actuator around a pivot, as can be seen in this 727 drawing. The actuating system is different on newer aircraft, but the idea is the same.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RncVK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RncVK.png&quot; alt=&quot;B727 stabilizer&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="598" LastActivityDate="2016-06-01T09:42:20.580" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27942" PostTypeId="2" ParentId="27934" CreationDate="2016-06-01T13:38:00.317" Score="2" Body="&lt;p&gt;I can point you at some reference materials you can use. These methods involve estimates for different types of aircraft and formulas you can use to estimate the component weight based on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Maximum_takeoff_weight&quot; rel=&quot;nofollow&quot;&gt;MTOW&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Operating_empty_weight&quot; rel=&quot;nofollow&quot;&gt;OEW&lt;/a&gt;, for example.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can use the following books:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/1884885241&quot; rel=&quot;nofollow&quot;&gt;Roskam - Airplane design&lt;/a&gt; (a series of books)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;http://rads.stackoverflow.com/amzn/click/9024727243&quot; rel=&quot;nofollow&quot;&gt;Egbert Torenbeek - Synthesis of Subsonic Airplane Design&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Jane%27s_All_the_World%27s_Aircraft&quot; rel=&quot;nofollow&quot;&gt;Jane's All the World's Aircraft&lt;/a&gt; (over 600 aircraft)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://scholar.google.com/&quot; rel=&quot;nofollow&quot;&gt;scholar.google.com&lt;/a&gt; is another good source for finding articles about landing gear systems and design in general.&lt;/p&gt;&#xA;" OwnerUserId="15202" LastEditorUserId="62" LastEditDate="2016-06-01T15:11:03.533" LastActivityDate="2016-06-01T15:11:03.533" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27943" PostTypeId="2" ParentId="27921" CreationDate="2016-06-01T13:51:10.760" Score="6" Body="&lt;p&gt;Not only does the FAA define standard passenger weights they have a lengthy AC describing how you should calculate loading. You &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC120-27E.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;can find that AC here&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4. What should an operator consider while reading this AC?&lt;/strong&gt; &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;a.&lt;/strong&gt; Accurately calculating an aircraft’s weight and CG before flight is&#xA;  essential to comply with the certification limits established for the&#xA;  aircraft. These limits include both weight and CG limits. By complying&#xA;  with these limits and operating under the procedures established by&#xA;  the manufacturer, an operator is able to meet the weight and balance&#xA;  requirements specified in the aircraft flight manual (AFM). Typically,&#xA;  an operator calculates takeoff weight by adding the operational empty&#xA;  weight (OEW) of the aircraft, the weight of the passenger, cargo&#xA;  payload, and the weight of fuel. The objective is to calculate the&#xA;  takeoff weight and CG of an aircraft as accurately as possible. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;b.&lt;/strong&gt; When using average weights for passengers and bags, the operator must&#xA;  be vigilant to ensure that the weight and balance control program&#xA;  reflects the reality of aircraft loading. The FAA will periodically&#xA;  review the guidance in this AC and update this AC if average weights&#xA;  of the traveling public should change or if regulatory requirements&#xA;  for carry-on bags or personal items should change. Ultimately, the&#xA;  operator is responsible for determining if the procedures described in&#xA;  this AC are appropriate for use in its type of operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You may be particularly interested in &lt;strong&gt;&lt;em&gt;CHAPTER 2. METHODS TO DETERMINE THE WEIGHT OF PASSENGERS AND BAGS&lt;/em&gt;&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The opening of the chapter pretty much covers that deviations may happen &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;200. What should an operator consider when choosing the appropriate method?&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;a. For many years, operators of transport category aircraft&#xA;  have used average weights for passengers and bags to calculate an&#xA;  aircraft’s weight and balance, in accordance with standards and&#xA;  recommended practices. This method eliminates many potential sources&#xA;  of error associated with accounting for a large number of relatively&#xA;  light weights. However, differences between the actual weight of&#xA;  passengers and bags and the average weight of passengers and bags can&#xA;  occur when using average weights. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. Statistical probability dictates&#xA;  that the smaller the sample size (i.e., cabin size), the more the&#xA;  average of the sample will deviate from the average of the larger&#xA;  universe. Because of this, the use of standard average passenger&#xA;  weights in weight and balance programs for small and medium cabin&#xA;  aircraft should be examined in greater detail. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;c. The next four&#xA;  sections describe four methods available to operators to determine&#xA;  passenger and bag weight. They are standard average weights in Section&#xA;  2; average weights based on survey results in Section 3; segmented&#xA;  weights in Section 4; and actual weights in Section 5. An operator&#xA;  should review the following discussion and consult Table 2-1 to&#xA;  determine which method or methods are appropriate to its type of&#xA;  operation.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I will refrain from quoting the rest of the document but its worth a read on covers the topic well, it should answer the main body of this question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also of interest may be &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/phak%20-%20chapter%2009.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;the FAA handbook on weight and balance&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From an operations stand point there are things to consider as well. First off airplanes have a CG range, not a single CG point. This range does in fact have some room to play with. The airlines only need to be within this range for TO/LD. Check out the &lt;a href=&quot;https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/phak%20-%20chapter%2009.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA handbook&lt;/a&gt; for more on CG ranges. In theory the airline can (and does on occasion) move people around, although my understanding is that this happens more so in smaller commercial planes. When I fly &lt;a href=&quot;https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee&quot; rel=&quot;nofollow noreferrer&quot;&gt;the Archer or Warrior&lt;/a&gt; I typically fly you better believe all my passengers are stepping on a scale before the flight!   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some planes may have ways to mitigate this to an extent. Depending on airframes the fuel loading can be distributed differently among the tanks but you still must be with in limits for TO/LD of course. Any large plane that may also be carrying cargo (for shipping reasons not the baggage its self) may have some ability to rearrange the pallets to keep the CG within limits but this again depends on the situation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-- EDIT (in response to CG range question in the comments below)--&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for how the planes are designed to handle this there is a CG range. This varies from plane to plane and some have bigger ranges than others. A full break down on how that works could be the subject of its own question here. Generally speaking there is a Max Takeoff weight that must fall with in a CG envelope. Here is the CG envelope for a Piper Warrior&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hfP0H.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hfP0H.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.fireair.co.uk/images/W&amp;amp;B.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The charts for airliners have bigger numbers and some more boxes but its easier to describe the issue with a chart like this. As you can see at max gross weight you have 6 inches of CG play. While this may not seem like a lot its more than enough to play with when loading the plane. This leaves room to have passengers of different weights in different seats etc. For the sake of a complete answer it should be noted that these ranges are just the tested limits of the airframe if your CG falls out of these ranges the plane may still fly however it will exhibit different behaviors (high/lower cruise speed, easier entry to a stall or tougher exit etc.). There have been &lt;a href=&quot;https://en.wikipedia.org/wiki/National_Airlines_Flight_102&quot; rel=&quot;nofollow noreferrer&quot;&gt;various accidents in history&lt;/a&gt; that happened as the result of a massive CG shift in flight, there is some debate as to the role that the &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_France_Flight_4590&quot; rel=&quot;nofollow noreferrer&quot;&gt;over loading of AF4590&lt;/a&gt; (the Concorde that crashed) played in the accident. You should be able to find similar CG range charts for most modern airliners out there if you want more specific ranges.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-06-04T19:10:09.113" LastActivityDate="2016-06-04T19:10:09.113" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27944" PostTypeId="1" CreationDate="2016-06-01T16:30:38.073" Score="2" ViewCount="243" Body="&lt;p&gt;Is there a product or some other way to track an aircraft's use, even if the pilot doesn't file an IFR flight plan, to let the owner know if it's used without authorization?&lt;/p&gt;&#xA;" OwnerUserId="15203" LastEditorUserId="62" LastEditDate="2016-06-01T21:32:37.820" LastActivityDate="2016-07-08T18:35:46.210" Title="How can an aircraft owner/operator track unauthorized flights?" Tags="&lt;security&gt;" AnswerCount="1" CommentCount="10" ContentLicense="CC BY-SA 3.0" />
  <row Id="27945" PostTypeId="1" AcceptedAnswerId="27968" CreationDate="2016-06-01T18:33:31.593" Score="14" ViewCount="11900" Body="&lt;p&gt;I have a chart where the thrust ($F$) and the &lt;em&gt;thrust-specific fuel consumption&lt;/em&gt; (TSFC) are plotted against the aircraft flying speed, for several altitudes (i.e. sea level, 3000 meters and 11000 meters). This is for a generic turbojet.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/zjhCF.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/zjhCF.jpg&quot; alt=&quot;chart01&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't know the source of the image, I apologize for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the left, we see that the thrust decreases with altitude. At the right, we observe that the TSFC actually decreases with altitude as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, I think this is counter-intuitive. I understand that $F$ decreases with altitude, since density (and therefore mass flow rate) decreases when the airplane goes up.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What I don't understand is that the TSFC, defined as: $$\text{TSFC}\equiv\dfrac{\text{fuel mass flow rate}}{F}$$ decreases with altitude. In other words, the higher we fly, the more thermodynamically-efficient the airplane is. How does that happen?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From a &lt;em&gt;pure mathematical point of view&lt;/em&gt;, it doesn't make sense that TSFC decreases with altitude since, following the aforementioned formula, $F$ is decreasing, which leads me to think that the fuel mass flow rate diminishes with altitude faster than thrust.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;In a nutshell:&lt;/strong&gt; why does the TSFC decreases with the flying altitude, having the last equation into consideration?&lt;/p&gt;&#xA;" OwnerUserId="7990" LastEditorUserId="609" LastEditDate="2017-02-08T16:32:42.863" LastActivityDate="2018-04-15T22:10:19.637" Title="Why does fuel consumption decrease with increasing aircraft altitude?" Tags="&lt;jet-engine&gt;&lt;aircraft-performance&gt;&lt;fuel&gt;&lt;altitude&gt;" AnswerCount="4" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27947" PostTypeId="1" CreationDate="2016-06-01T20:04:35.577" Score="1" ViewCount="6877" Body="&lt;p&gt;I am trying to use METAR data from &lt;a href=&quot;http://aviationweather.gov/adds/metars&quot; rel=&quot;nofollow&quot; title=&quot;AviationWeather.gov&quot;&gt;AviationWeather.gov&lt;/a&gt; to programmatically collect hourly rainfall data.  &lt;a href=&quot;https://en.wikipedia.org/wiki/METAR&quot; rel=&quot;nofollow&quot; title=&quot;wiki&quot;&gt;This Wiki&lt;/a&gt; says that the first field in the report should be &quot;type&quot; - either METAR or SPECI.  METARs are sent every hour, SPECIs are sent sporadically under certain conditions.  The problem is that the AviationWeather.gov reports are missing that first field, so I can't tell the difference between METAR and SPECI reports.  I care because I can only get reliable cumulative Rainfall data from the METAR reports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What am I missing?&lt;/p&gt;&#xA;" OwnerUserId="15204" LastEditorUserId="62" LastEditDate="2016-06-01T20:16:47.680" LastActivityDate="2016-06-01T20:44:54.000" Title="How to tell the difference between METAR and SPECI reports?" Tags="&lt;weather&gt;&lt;usa&gt;&lt;datasets&gt;&lt;metar&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27948" PostTypeId="2" ParentId="27947" CreationDate="2016-06-01T20:44:54.000" Score="1" Body="&lt;p&gt;I don't think you can use METARs to produce precise hourly rainfall data. METARs do not express the exact amount of precipitation; rain is only expressed in three categories (light, moderate, heavy).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The way I understand your problem, you want to skip SPECI reports because you only want a single report per hour. A better way of doing this would be to use the time/date stamp in the report and simply dismiss a report if you already have one from the same hour. Say you have a report from 011203Z and you then receive another report from 011220Z. You want to dismiss the last report, because it is only 17 minutes older than the first one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Alternatively, you can find METARs from a number of other sources, which include the message designator as well. Here is one I find useful: &lt;a href=&quot;http://www.ogimet.com/metars.phtml.en&quot; rel=&quot;nofollow&quot;&gt;http://www.ogimet.com/metars.phtml.en&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-06-01T20:44:54.000" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27949" PostTypeId="1" CreationDate="2016-06-01T22:31:26.187" Score="1" ViewCount="400" Body="&lt;p&gt;Drag increases with the square of airspeed. Is the same true of the pressure that a forward-facing area experiences?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an aircraft approaches and then exceeds the speed of sound, how does experienced pressure on a forward-facing area increase?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-07T11:06:40.187" Title="How does experienced pressure vary with airspeed?" Tags="&lt;aerodynamics&gt;&lt;airspeed&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27950" PostTypeId="1" CreationDate="2016-06-02T02:13:01.787" Score="2" ViewCount="680" Body="&lt;p&gt;The context I am asking is regarding if electric motors could ease the fuel cost, take off weight, or runway length if they were set up in 'hybrid' configuration with regular hydrocarbon engines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If so, could potentially a military aircraft (IE, F35) have any weight savings or feature benefit of having an electrically boosted STOVL/VTOL system? Any fuel savings over regular flight? And of course, would this make sense at all from an engineering standpoint, today or ten years from now?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I am not asking the ability of electrical propulsion systems to replace the current main prop or jet systems, but rather to the alternative capacity that they might offer in other auxiliary or backup uses.&lt;/strong&gt;&lt;/p&gt;&#xA;" OwnerUserId="15196" LastEditorUserId="15196" LastEditDate="2016-06-02T15:13:37.697" LastActivityDate="2016-06-02T17:50:12.880" Title="What are some alternative benefits to electric propulsion?" Tags="&lt;aircraft-performance&gt;&lt;experimental-aircraft&gt;&lt;electric-engine&gt;" AnswerCount="2" CommentCount="4" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27951" PostTypeId="2" ParentId="12830" CreationDate="2016-06-02T02:23:53.547" Score="1" Body="&lt;p&gt;You've asked about different doors. I'll skip the standard, rectangular pull in/push out door and the L1011-style door you've mentioned.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some examples:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FoPVo.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FoPVo.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/PPhoZ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/PPhoZ.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/IJ2YH.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/IJ2YH.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ytZYT.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ytZYT.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/VVatm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/VVatm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/0zB7t.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/0zB7t.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-06-02T02:23:53.547" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27952" PostTypeId="1" AcceptedAnswerId="27956" CreationDate="2016-06-02T05:28:02.713" Score="27" ViewCount="5996" Body="&lt;p&gt;This is one of the videos of the crash: &lt;a href=&quot;https://www.youtube.com/watch?v=oYmaP5OKWBQ&quot;&gt;727 Test Crash&lt;/a&gt;. It seems it was more of a hard landing without gears. Why wouldn't the experimenters have made it more of a really hard crash if they needed to study the effects of a crash on a plane? Would slamming down the plane really hard (maybe even nose down) given a more realistic scenario and more valuable data rather than making it soft?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="753" LastEditDate="2016-06-02T20:26:08.517" LastActivityDate="2016-06-03T09:22:18.250" Title="Why are test crashes not made harder on the airframe?" Tags="&lt;safety&gt;&lt;accident-investigation&gt;" AnswerCount="4" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27953" PostTypeId="1" AcceptedAnswerId="27954" CreationDate="2016-06-02T05:55:45.120" Score="5" ViewCount="469" Body="&lt;p&gt;In the &lt;a href=&quot;http://www.hondajet.com/gallery-and-downloads/videos#3&quot; rel=&quot;nofollow noreferrer&quot;&gt;third Hondajet marketing video&lt;/a&gt; there is a sword-like object visible on the nose of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is this used for?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/fy5vR.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/fy5vR.jpg&quot; alt=&quot;still from Hondajet marketing video #3&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14240" LastEditorUserId="1467" LastEditDate="2016-06-02T21:03:26.060" LastActivityDate="2016-06-02T21:03:26.060" Title="What is the object on the nose of this HondaJet in this marketing video?" Tags="&lt;nose&gt;&lt;hondajet&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27954" PostTypeId="2" ParentId="27953" CreationDate="2016-06-02T06:22:10.807" Score="7" Body="&lt;p&gt;It is a &lt;a href=&quot;https://en.wikipedia.org/wiki/Pitot_tube&quot; rel=&quot;nofollow noreferrer&quot;&gt;Pitot tube&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is used to measure some air data values, depending on the model.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The most basic will measure only pressures (and then &quot;derives&quot; the velocity of the aircraft), the most advanced will measure angle of attack and sideslip as well.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The one in the photo is particularly long to make sure that is measuring values in the undisturbed airflow in front of the aircraft. It is a model usually seen in flight tests or on fighter aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In flight tests, because despite the accurate CFD modelling available today, uncertainties are still present during the first flights (that's why they are tests). The long probe gives a reference as much undisturbed as possible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;During normal operations you will generally find smaller probes, such as the ones found in &lt;a href=&quot;https://aviation.stackexchange.com/q/5009/1467&quot;&gt;this&lt;/a&gt; other question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Fighter aircraft need the long boom for the reasons seen in &lt;a href=&quot;https://aviation.stackexchange.com/q/7457/1467&quot;&gt;this&lt;/a&gt; question.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-06-02T11:28:12.517" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="27955" PostTypeId="2" ParentId="27952" CreationDate="2016-06-02T06:26:22.547" Score="29" Body="&lt;p&gt;Because they wanted to analyse survivability, making the crash non survivable would have defeated the point. &lt;/p&gt;&#xA;" OwnerUserId="1467" LastActivityDate="2016-06-02T06:26:22.547" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27956" PostTypeId="2" ParentId="27952" CreationDate="2016-06-02T07:32:05.930" Score="61" Body="&lt;p&gt;If the plane crashes with high vertical speed, the decelerations involved are so insanely huge that there is absolutely no way to make it survivable. That is well explained in &#xA;&lt;a href=&quot;https://aviation.stackexchange.com/q/16545/524&quot;&gt;Even after years of research, why are planes unable to keep passengers alive in case of a fiery crash?&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However in many cases the aircraft is still, at least partially, controllable, so a crash-landing can be made. And that is the case where survivability can be improved by careful design, so that is the case they were testing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is also relevant for accidents on landing where the aircraft simply does not have that much vertical speed. Together these scenarios cover more accident cases than the out of control scenario.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-06-02T12:29:08.657" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27957" PostTypeId="2" ParentId="27949" CreationDate="2016-06-02T07:35:22.790" Score="1" Body="&lt;p&gt;1) Pressure is simply a force divided by an area, so yes: The dynamic pressure experienced by a forward-facing surface will, in an incompressible flow, vary with the square of the speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;2) The dynamic pressure increases dramatically as one approaches the speed of sound, once going faster than mach one the pressure will begin to decrease. The trans-sonic phase (around mach one) is difficult to describe and can depend on the airflow around the body - but in many cases it can be quite stable.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;-edit-&#xA;For the second question here's a couple of links that can provide more information:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://www.scielo.br/scielo.php?script=sci_arttext&amp;amp;pid=S1678-58782005000400017&quot; rel=&quot;nofollow&quot;&gt;Transonic flow around a rocket&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;&lt;a href=&quot;http://history.nasa.gov/SP-4219/Chapter3.html&quot; rel=&quot;nofollow&quot;&gt;NASA history of transonic research&lt;/a&gt;&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="12234" LastEditorUserId="14197" LastEditDate="2016-06-07T11:06:40.187" LastActivityDate="2016-06-07T11:06:40.187" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27959" PostTypeId="2" ParentId="27950" CreationDate="2016-06-02T08:24:55.927" Score="8" Body="&lt;p&gt;For aircraft, &lt;strong&gt;none&lt;/strong&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Hybrid drive trains are used because:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;They offer, &lt;em&gt;rather limited&lt;/em&gt;, efficiency improvement by being able to operate the engine closer to its optimal conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because &lt;em&gt;spark-ignition&lt;/em&gt; engines are more efficient at higher power settings, the hybrid can get advantage by having smaller engine, running it at (relatively) high power or not at all and cover the variations in required power using the electric engine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Cars accelerate and stop a lot and often cruise at small fraction of power, so they can make good use of this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The advantage only applies to spark-ignition, i.e. gasoline, engines. &lt;em&gt;Compression-ignition&lt;/em&gt; (diesel) engines have more uniform efficiency over their operating range, so there is no or only negligible advantage. Which is part of the reason you don't see hybrid diesel cars.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Batteries can be pre-charged with cheaper mains power. This is used in the hybrid cars, but it obviously requires lots of &lt;em&gt;heavy&lt;/em&gt; batteries.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Electric motors can provide high torque from standstill. Piston engines can only provide limited torque from standstill and it stresses the clutch heavily.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is particularly important for train engines. Train wheels have bearings lubricated by oil pumps attached to the axles that only operate when the train is moving, so when the train is stopped, the bearings are not lubricated and the force required to get it moving is much higher then when moving.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;At high power outputs, electric generator and motor are simpler and more reliable than a gearbox and clutch. For big train engines and ships, mechanical clutch is out of question. Hydraulic one, which is a turbopump and turbine in oil, can be used, but that still needs variable gearbox. The electric drive-train acts as almost ideal continuously variable transmission, being able to deliver almost constant power over wide range or rotational speeds.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In either case the hybrid drive-train is heavier than mechanical one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now &lt;strong&gt;for aircraft&lt;/strong&gt;:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;The engine is run at constant speed and power setting, which is relatively high (usually cruise setting is 75% for piston and even higher for turbine planes). So there is no room to design a hybrid drive train to run the engine closer to optimal.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Weight is critical for aircraft, so the weight of electric generator and motor is a show-stopper there. For cars adding weight causes smaller increase in drag, so its less of a concern and trains even need to be heavy to have enough adhesion for their traction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Since weight is critical, aircraft can't afford to take much batteries that could be pre-charged with cheaper mains electricity, the other benefit hybrid cars have.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Propellers need almost no force to start spinning and are operated at narrow range of RPM, so the ability of electric motor to provide torque from standstill and across wide range of RPM is of no use to aircraft.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So none of the benefits for which hybrid drive trains are used in other vehicles is applicable to aircraft, so there is no point in building one.&lt;/p&gt;&#xA;" OwnerUserId="524" LastEditorUserId="524" LastEditDate="2016-06-02T13:37:29.690" LastActivityDate="2016-06-02T13:37:29.690" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27960" PostTypeId="1" CreationDate="2016-06-02T11:25:16.700" Score="1" ViewCount="625" Body="&lt;p&gt;I have been an ardent aviation geek since childhood and always wanted to be flying commercially. But sometime later during a medical examination through Ishihara plates test I learned that I am color blind. I have been reading quite a lot about colour blind people are considered to be medically unfit to fly. So I just wanted to confirm if this is true or should I go and take some additional test before I let go of my dream.&lt;/p&gt;&#xA;" OwnerUserId="15213" LastEditorUserId="5517" LastEditDate="2016-06-02T11:47:21.800" LastActivityDate="2016-06-02T11:47:21.800" Title="Can a colour blind person pursue a career in Commercial Flying?" Tags="&lt;commercial-aviation&gt;&lt;pilots&gt;&lt;medical&gt;&lt;regulations&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2016-06-02T12:46:39.053" ContentLicense="CC BY-SA 3.0" />
  <row Id="27961" PostTypeId="2" ParentId="27949" CreationDate="2016-06-02T13:07:34.730" Score="0" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Drag increases with the square of airspeed. Is the same true of the pressure that a forward-facing area experiences?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Drag increases with the square of the airspeed because it is a function of the dynamic pressure $\bar{p}$:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$D = C_D A \bar{p} =  C_D A \frac{1}{2} \rho V^2$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So the answer is yes, because the drag is a function of the (dynamic) pressure that a forward-facing area experiences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do not speak of the static pressure because that is a function of the atmospheric conditions, and is not a function of the movement of the aircraft through the atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;As an aircraft approaches and then exceeds the speed of sound, how does experienced pressure on a forward-facing area increase?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I think this has been addressed in the answers &lt;a href=&quot;https://aviation.stackexchange.com/q/25089/1467&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="1467" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-06-02T13:07:34.730" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27962" PostTypeId="1" AcceptedAnswerId="27965" CreationDate="2016-06-02T14:05:30.480" Score="4" ViewCount="1422" Body="&lt;p&gt;In this situation, I would be flying from Richmond Executive-Chesterfield (FCI) to New Kent Co (W96).  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Can I land at an uncontrolled airport under class C without talking to ATC?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Picture source: SkyVector&#xA;&lt;a href=&quot;https://i.stack.imgur.com/WWfik.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WWfik.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13972" LastEditorUserId="13972" LastEditDate="2016-06-02T20:46:51.503" LastActivityDate="2016-06-02T20:56:41.490" Title="Can I land at an uncontrolled airport under class C without talking to ATC?" Tags="&lt;radio-communications&gt;&lt;navigation&gt;&lt;airspace&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27963" PostTypeId="2" ParentId="27952" CreationDate="2016-06-02T14:38:28.127" Score="3" Body="&lt;p&gt;The basic principle of the airworthiness regulations is risk analysis. If you can demonstrate that a particular scenario has a sufficiently low risk of ever happening, you don't need to consider the consequences if it does happen. As an order of magnitude, &quot;sufficiently low risk&quot; means you might expect something to happen at most once during the full lifetime of all the aircraft of that type - which may be a period of 50 years or more for a popular aircraft type where thousands of aircraft were manufactured.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Landing a partly controllable aircraft with the gear up is more likely to happen than that &quot;extremely rare&quot; probability, so you need to demonstrate what the consequences are, hence the test. But there are thousands of possible but extremely unlikely scenarios that could (and most likely would) lead to the loss of the aircraft. For those scenarios, you design to reduce the risk of the event happening at all, not to deal with the consequences if it does happen. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A topical example: you don't try to design planes that will survive explosions in mid flight. Rather, you try to design systems to ensure that planes don't &lt;em&gt;carry&lt;/em&gt; explosive material in the first place.&lt;/p&gt;&#xA;" OwnerUserId="8206" LastActivityDate="2016-06-02T14:38:28.127" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27964" PostTypeId="2" ParentId="27962" CreationDate="2016-06-02T15:38:17.907" Score="3" Body="&lt;p&gt;I would just proceed under the shelf and pick up flight following enroute. If you're under the shelf, you don't have to talk to ATC at all, however I think it would be a good idea as you'll be crossing the extended centerline of all three runways at some point during your flight. Once you get flight following, you can gain altitude and possibly cut straight through the center ring as well.&lt;/p&gt;&#xA;" OwnerUserId="15218" LastActivityDate="2016-06-02T15:38:17.907" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27965" PostTypeId="2" ParentId="27962" CreationDate="2016-06-02T15:40:29.133" Score="12" Body="&lt;p&gt;It looks to me like New Kent is entirely &lt;strong&gt;&lt;em&gt;below&lt;/em&gt;&lt;/strong&gt; the shelf of the class C space.   You don't need to go through the Class C Core at all, so I don't see that you need to speak to them.  The detour to avoid the core looks minimal&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see the shelf height shown as 42/14, meaning that the class C space starts at 1400 feet, and goes up to 4200 feet.   Just stay below the shelf, at about 1100 feet. At that altitude, pay extra attention to any obstacles like radio antennas!  I do see several obstacles going up to 500 / 600 feet!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you want to let them know of your intentions, I'd just say:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&quot;Potomac Approach: N12345, Departing Richmond Exec, to New Kent, VFR below Class C.  On Frequency.&quot;&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They will likely respond with:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;&quot;N12345: Proceed as requested. Maintain VFR&quot;&lt;/em&gt;&#xA;&lt;hr&gt;&lt;hr&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://skyvector.com/?ll=37.449405240185456,-77.31099700289352&amp;amp;chart=301&amp;amp;zoom=1&amp;amp;fpl=%20KFCI%203723N07730W%203725N07716W%203730N07710W%20W96&quot; rel=&quot;noreferrer&quot;&gt;&lt;strong&gt;&lt;em&gt;Link to Flight Diagram&lt;/em&gt;&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2016-06-02T20:03:42.697" LastActivityDate="2016-06-02T20:03:42.697" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27966" PostTypeId="2" ParentId="26353" CreationDate="2016-06-02T15:45:46.173" Score="2" Body="&lt;p&gt;There are instances of interviews where Musk describes in detail what the intention is.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft's main advantage would be in his opinion, would be the ability to conduct high altitude flight in envelopes where engines requiring atmospheric oxygen to combust could not operate, thus able to move faster with less resistance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;He also talks about gimballing engines for control surfaces, and using it to have VTOL capacity.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The biggest issue right now is power density for it to even exist, but from a design stand point, I'm not sure that it would be wisest to leave your control surfaces to JUST the engines. The biggest benefits to having tails, canards etc, is that in the event of engine failure, you don't turn into a brick. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;And also in higher altitudes, around (At least higher than 20km) 40-60 km, I imagine you might need RCS like control systems as backup.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But getting to the 'jet' part, I believe that it's precisely what you think of it as, a 'turbofan' with the core powered by a motor and gimballed.&lt;/p&gt;&#xA;" OwnerUserId="15196" LastActivityDate="2016-06-02T15:45:46.173" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27967" PostTypeId="2" ParentId="27950" CreationDate="2016-06-02T17:50:12.880" Score="1" Body="&lt;p&gt;I agree with the previous answer that there are a number of issues with implementing a serial hybrid (e.g., a chemically powered generator running electric motor(s)) on an aircraft, but I think there are a couple of positive sides to it as well...though we may have to design a new propulsion system rather than supplement an existing one.  I found a NASA study looking at distributed turboelectric propulsion to replace cryogenically stored hydrogen scramjets on a BWB aircraft which shows the potential to actually save weight by moving over to the electric system (&lt;a href=&quot;https://mdao.grc.nasa.gov/publications/IPLF08-Kim.pdf&quot; rel=&quot;nofollow&quot;&gt;https://mdao.grc.nasa.gov/publications/IPLF08-Kim.pdf&lt;/a&gt;), but that's a pretty niche application.  This, naturally, does not universally imply that that is the case, however: just for now and for that application.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the mention of &lt;em&gt;distributed&lt;/em&gt; propulsion does highlight a major plus for electric propulsion systems.  It's dramatically easier to route flexible power lines than mechanical shaft connections.  Hence, if you want to have multiple engines...electric propulsion enables you to do that relatively easily.  Also, say that you want to make an aircraft that can hover and cruise as a typical fixed wing aircraft -- typically, you'd have to design collective pitch change into your proprotors.  Or, with electric propulsion, you could just have a bunch (I mean 12+) of proprotors, each of which you tailor with a twist distribution proper to a certain mode of flight.  Look at a proposed NASA design (&lt;a href=&quot;http://aero.larc.nasa.gov/files/2012/11/Distributed-Electric-Propulsion-Aircraft.pdf&quot; rel=&quot;nofollow&quot;&gt;http://aero.larc.nasa.gov/files/2012/11/Distributed-Electric-Propulsion-Aircraft.pdf&lt;/a&gt;), a separate design by Aurora Flight Sciences that has advanced in the DARPA X-Plane program (&lt;a href=&quot;http://www.darpa.mil/news-events/2016-03-03&quot; rel=&quot;nofollow&quot;&gt;http://www.darpa.mil/news-events/2016-03-03&lt;/a&gt;), or Lilium Aviation's recent design (&lt;a href=&quot;http://lilium-aviation.com/&quot; rel=&quot;nofollow&quot;&gt;http://lilium-aviation.com/&lt;/a&gt;).  Given all of these are &lt;em&gt;concepts&lt;/em&gt;, so nothing is proven by a working design as of yet...but it seems like a lot of people are looking into the possibilities afforded by a distributed electrical propulsion system.  The expected advent of lithium-sulfur batteries should be a big deal here too.  These batteries are expected to have a capacity of ~500 kWh/kg (about 2x the absolute best Li-poly available now), but I think that 2019 is the expected date for high-capacity Li-S batteries to start hitting the market.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, one thing about engines is that their efficiency can vary dramatically depending on how they are being run (i.e., the load on the engine, RPM, etc.).  This excerpt from a German textbook is, unfortunately, in German (&lt;a href=&quot;https://books.google.com/books?id=QAGHZPVnnSAC&amp;amp;pg=PA540#v=onepage&amp;amp;q&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;https://books.google.com/books?id=QAGHZPVnnSAC&amp;amp;pg=PA540#v=onepage&amp;amp;q&amp;amp;f=false&lt;/a&gt;), but the basic idea is reflected on a Wikipedia page where the plot is reproduced in English (&lt;a href=&quot;https://en.wikipedia.org/wiki/Consumption_map&quot; rel=&quot;nofollow&quot;&gt;https://en.wikipedia.org/wiki/Consumption_map&lt;/a&gt;).  On the vertical axis is power output of a spark-ignition engine, the horizontal axis is the RPM that the motor is being run at, the the contours are, essentially, fuel consumption.  The long and the short of it is that, if you have any change in the engine's load or what RPM it's running at, it's not running at its most efficient.  This would be the case for your typical non-hybrid propulsion, where load and RPM vary with flight condition.  However, if we decouple flight condition (i.e., desired cruise speed, throttle setting, prop speed setting, prop pitch setting, etc.) from the chemical engine and let an electric motor (which has a much higher efficiency than a chemical engine) deal with these variations, we can, conceivably, run the chemical engine within an optimal performance range (some variation will probably be needed if power output is excessive, but that's a design problem wherein you'd try to size the engine for its most efficient in cruise, I'd think).  That's a fuel savings for us, plus a decrease on engine wear because it doesn't have to see all the throttle variations typically present in normal flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted, this isn't the case for a typical airplane (small RPM bands)...but what if we decided to play the game that Aurora, Lilium, and NASA are playing and make VTOL/STOVL aircraft?  The differences between flying a proprotor in edgewise and axial flight are dramatic, and having RPM control can make a lot of difference and might obviate a need for variable pitch propellers.  Just design your twist distribution right, vary your RPM, and you just might be able to get acceptable efficiency in both regimes (at least for slower speeds).  Or, like NASA, use two different sets of proprotors for a fixed-wing cruise and vertical flight, each one optimized for that specific flight regime.  I'm not saying it's easy...just that electric propulsion makes the opportunity present.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But, yes, weight and technology are major concerns...and you can see in the electric aircraft that have been built to date.  Firefly (Sikorsky's electric helicopter) has a max endurance, I think, of 15 minutes.  Helios (&lt;a href=&quot;https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-068-DFRC.html&quot; rel=&quot;nofollow&quot;&gt;https://www.nasa.gov/centers/armstrong/news/FactSheets/FS-068-DFRC.html&lt;/a&gt;) is a neat aircraft, but look at how flimsy the design is in order to enable it work as a solar/fuel-cell hybrid (i.e., solar just doesn't provide a lot of power, so you need to make a light, high-aspect ratio aircraft).  The Gamera-S is a solar-powered quadcopter under development at the University of Maryland (see below), but look at how sparse the frame is--weight is a HUGE problem for these aircraft, especially given how much power we can currently get from batteries or the sun.  Serial hybrids don't get rid of that problem (since it introduces engine weight, fuel weight, lubrication system weight, etc.) but it can give you a couple of perks, as noted above.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/nP03nHievKM?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="14720" LastActivityDate="2016-06-02T17:50:12.880" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27968" PostTypeId="2" ParentId="27945" CreationDate="2016-06-02T18:05:33.260" Score="8" Body="&lt;p&gt;I can't provide the math, but yes, this is correct. Fuel flow decreases as air density decreases. The engine becomes more efficient because of the greater temperature differential between inlet and exhaust gases combined with the lower fuel flow.&lt;/p&gt;&#xA;" OwnerUserId="9298" LastActivityDate="2016-06-02T18:05:33.260" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27969" PostTypeId="1" AcceptedAnswerId="27975" CreationDate="2016-06-02T18:34:51.813" Score="7" ViewCount="2765" Body="&lt;p&gt;Consider picking a plane for weather study. This plane will intentionally fly into weather systems (e.g. inside the eye of a hurricane) to collect scientific data. It will be equipped with on-board weather radar and other atmospheric sensors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which airframe designs are most suitable for this type of flying?&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;4 engines is probably a must for reliability&lt;/li&gt;&#xA;&lt;li&gt;Piston? Turbo-prop? Turbo-fan?&lt;/li&gt;&#xA;&lt;li&gt;Low wing? High wing?&lt;/li&gt;&#xA;&lt;li&gt;Low / high aspect ratio?&lt;/li&gt;&#xA;&lt;li&gt;Delta wing? Sweep wing?&lt;/li&gt;&#xA;&lt;li&gt;Conventional tail? T tail?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;You get the idea...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: I would also like to know why the current planes are chosen. For example, if delta wing is not used, then it suggests a certain criteria which cannot be met by the delta wing design (e.g. requires high AoA at low speeds).&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-06-02T19:11:44.423" LastActivityDate="2016-06-02T22:12:14.983" Title="What airframe design is best for stormy weather?" Tags="&lt;aircraft-design&gt;&lt;weather&gt;" AnswerCount="3" CommentCount="2" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27970" PostTypeId="2" ParentId="27969" CreationDate="2016-06-02T18:54:25.407" Score="3" Body="&lt;p&gt;Planes that actually fly &lt;a href=&quot;https://en.wikipedia.org/wiki/Hurricane_Hunters&quot; rel=&quot;nofollow&quot;&gt;into a hurricane&lt;/a&gt; for such purposes all the time are the C-130 and P-3 both of which are quadruple turbo-prop airplanes. As the C-130 is high-wing and the P-3 is low-wing, that part does not really matter. Both planes also have relatively straight wings and not swept back in any way as well as conventional tails. The P-3 has an aspect ratio of 7:5 and the C-130 has an aspect ratio of 10.1.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So basically, get a military plane with 4 turbo-prop planes and you are safe to go as we do it nowadays. &lt;/p&gt;&#xA;" OwnerUserId="12220" LastActivityDate="2016-06-02T18:54:25.407" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27971" PostTypeId="2" ParentId="27969" CreationDate="2016-06-02T18:59:04.920" Score="8" Body="&lt;p&gt;To answer this, let's look at the planes primarily being used for this task today: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;the  &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Lockheed_WP-3D_Orion&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed WP-3D Orion&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/ajQ93.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ajQ93.jpg&quot; alt=&quot;Orion &quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;and the &lt;a href=&quot;https://en.m.wikipedia.org/wiki/Lockheed_WC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;Lockheed WC-130&lt;/a&gt;&lt;br&gt;&#xA;&lt;a href=&quot;https://i.stack.imgur.com/b1Cj6.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/b1Cj6.jpg&quot; alt=&quot;C130&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These planes both feature 4 engines like you suggested, likely both for reliability and for the fact that they are rather large planes in order to maximize instrument and sensor space, as well as stability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;They are both powered by turboprops, which is likely due to the compromise provided between speed, range, efficiency, and reliability. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One has a low wing and the other a high wing, indicating that this is not a primary concern, as they have both been operational for decades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aspect ratios are relatively moderate, again indicating a compromise between performance and stability. The wings feature little sweep, reflective of the emphasis on stability and range over speed. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally, both feature a conventional tail, suggesting that simpler, more reliable designs are favored over designs that are more complex to maintain. &lt;/p&gt;&#xA;" OwnerUserId="13371" LastEditorUserId="12720" LastEditDate="2016-06-02T22:12:14.983" LastActivityDate="2016-06-02T22:12:14.983" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27972" PostTypeId="1" AcceptedAnswerId="27985" CreationDate="2016-06-02T19:09:51.867" Score="9" ViewCount="2475" Body="&lt;p&gt;Some version of B737 have built in stair, which allows passengers boarding and exit without jet bridge or stair car.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How much do the stair systems weigh? And how much volume do they occupy?&lt;/p&gt;&#xA;" OwnerUserId="8000" LastEditorUserId="12220" LastEditDate="2016-06-02T19:15:21.730" LastActivityDate="2016-06-03T12:30:26.920" Title="How large and heavy is the B737's built-in stair?" Tags="&lt;boeing-737&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27973" PostTypeId="1" CreationDate="2016-06-02T19:56:18.957" Score="2" ViewCount="1390" Body="&lt;p&gt;How much money do commercial pilots make per year, and per hour? Is there significant non-monetary compensation, such as free hotels stays and food?&lt;/p&gt;&#xA;" OwnerUserId="1001" LastActivityDate="2016-06-05T00:35:49.667" Title="Do pilots make a lot of money?" Tags="&lt;pilots&gt;&lt;career&gt;" AnswerCount="1" CommentCount="6" ClosedDate="2016-06-02T20:25:37.890" ContentLicense="CC BY-SA 3.0" />
  <row Id="27974" PostTypeId="2" ParentId="27973" CreationDate="2016-06-02T20:14:58.593" Score="5" Body="&lt;p&gt;I can only answer from a US standpoint as that is the jurisdiction I know best, elsewhere in the world things may be different. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The first thing you can check is &lt;a href=&quot;http://www.bls.gov/ooh/transportation-and-material-moving/airline-and-commercial-pilots.htm&quot; rel=&quot;nofollow&quot;&gt;this data from the Bureau Of Labor And Statistics&lt;/a&gt; according to their data &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;2015 Median Pay&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;em&gt;The wage at which half of the workers in the occupation earned more&#xA;  than that amount and half earned less. Median wage data are from the&#xA;  BLS Occupational Employment Statistics survey. In May 2015, the median&#xA;  annual wage for all workers was $36,200.&lt;/em&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;For Pilots the 2015 median pay was 102,520 USD per year&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You should read over &lt;a href=&quot;http://thetruthabouttheprofession.weebly.com/professional-pilot-salaries.html&quot; rel=&quot;nofollow&quot;&gt;this article as well&lt;/a&gt; as it covers a wide variety of how pilots are paid and the such. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is some more &lt;a href=&quot;https://skift.com/2013/08/28/the-u-s-airline-pilots-who-barely-make-minimum-wage/&quot; rel=&quot;nofollow&quot;&gt;data on salary as well&lt;/a&gt;. You should how ever note that for many articles the data is submitted by choice and may not accurately reflect the true pay scale. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is &lt;a href=&quot;http://www.airliners.net/aviation-forums/general_aviation/read.main/845246/&quot; rel=&quot;nofollow&quot;&gt;some discussion on the per hour pay&lt;/a&gt; but I should caution you to be weary of per hour statistics for pilots. In many cases these numbers are computed using flight hours which does not accurately reflect how much a pilot may work as there is more time involved in a flight than just what the hobbs meter records. Here in the US it is my impression most commercial (121) pilots are salaried. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My two flight instructors recently went to the regionals after completing their ATP hours from talking to them it is evident that starting pay is very low (under 30K a year). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One interesting (and often debated issue) is that the &lt;a href=&quot;http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/E82EE36F043F887086257E62004FDE40?OpenDocument&amp;amp;Highlight=121.383&quot; rel=&quot;nofollow&quot;&gt;FAA requires pilots to retire at 65&lt;/a&gt; (was previously 60). This in theory puts a cap on their earning potential as an airline pilot (however they can fly non 121 operations like a 135 charter afterwords).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As for perks, that depends on the airline (and may to some extent depend on seniority). Its common to get some comped tickets for family members and the such but its not what it once was. I have heard that many pilots can fly standby on their own (or in company) airlines for free. They may also be able to ride in the jump seat if there is one. This can be attractive for a young single pilot but is not very efficient for family travel. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Free hotels and things will depend on the route you are flying. If overnight stay is required they may put the pilot up (i.e. long haul routes) but you should not expect 5 Star Penthouses and bottomless lobster dinners. However there are plenty of short routes for which a pilot may end up back at their base at the end of their shift.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are looking for a decent overview of the pilots life I would advise picking up a copy of &lt;a href=&quot;http://www.askthepilot.com/cockpitconfidential/&quot; rel=&quot;nofollow&quot;&gt;Cockpit Confidential&lt;/a&gt; it has a lot of the answer you may be looking for and is very to the point. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-06-05T00:35:49.667" LastActivityDate="2016-06-05T00:35:49.667" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="27975" PostTypeId="2" ParentId="27969" CreationDate="2016-06-02T20:18:23.660" Score="11" Body="&lt;p&gt;In observing the configuration of the current aircraft used for weather study, it's important to also note that those planes were originally built for different missions that allowed modifications for such a special purpose.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The P-3 was built as a maritime patrol plane, which is a role not all that different from weather observation. It requires good range and endurance to allow the plane to fly out to sea and remain there long enough to accomplish its mission. The primary mission is using sensors, either onboard or deployed from the aircraft. The plane must also be able to withstand more time spent at lower altitudes and in more turbulence than typical aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The C-130 was built as a transport plane. This requires good range and payload capacity, both in weight and volume. These attributes have allowed it to serve in many roles, such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_AC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;attack&lt;/a&gt;, &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_MC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;special operations transport&lt;/a&gt;, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Lockheed_EC-130&quot; rel=&quot;nofollow noreferrer&quot;&gt;electronic warfare&lt;/a&gt;. As both aircraft were originally built for the military, they are built to withstand higher loading than typical civilian aircraft, which is useful when flying to bad weather.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;4 engines are &lt;a href=&quot;https://aviation.stackexchange.com/q/18847/1696&quot;&gt;less efficient&lt;/a&gt; but provide redundancy&lt;/strong&gt; - Both aircraft have 4 engines, as this is a good compromise between size of engine and propeller for this size of aircraft, at the time at which they were designed (around 1960). &lt;a href=&quot;https://aviation.stackexchange.com/q/15037/1696&quot;&gt;This primarily provides redundancy&lt;/a&gt;. The plane is required to be able to fly with one engine failed, and controllable with two on the same wing failed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Turboprops are efficient at moderate speed&lt;/strong&gt; - Both aircraft are also powered by turboprops. The primary roles for the aircraft do not require high speeds or altitudes, which is where turbofans have an advantage. Turboprops provide good power and efficiency at moderate speeds and altitudes, which is acceptable for shorter cargo missions and maritime patrols as well as weather observation. It's worth noting that the US Navy is replacing the P-3 with the P-8, which is a twin engine jet aircraft. A large part of this is likely due to the availability of an existing aircraft design, not being worth the cost of designing an entirely new plane. Although two engines provide less redundancy, they can still provide a similar level of reliability. &lt;a href=&quot;https://en.wikipedia.org/wiki/Kawasaki_P-1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Japan designed an entirely new maritime patrol plane, and opted for 4 turbofans.&lt;/a&gt; Although turbofans may require more fuel, they do allow higher speeds which allows the aircraft to reach its station faster.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Low wing may be a more versatile configuration&lt;/strong&gt; - The high wing of the C-130 is mainly to allow easy loading and unloading of cargo by keeping the fuselage closer to the ground. This is less important for a weather observation role, though it does allow better downward visibility from the cabin. The P-3 sits higher above the ground, which allowed for a radar to be mounted underneath. Mounting sensors on top is &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737_AEW%26C&quot; rel=&quot;nofollow noreferrer&quot;&gt;certainly an option&lt;/a&gt; but may require &lt;a href=&quot;https://aviation.stackexchange.com/q/11808/1696&quot;&gt;modifications&lt;/a&gt; to retain stability. One might conclude that a low wing offers more versatility in this regard.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Moderate aspect ratio with sweep to match speed&lt;/strong&gt; - The &lt;a href=&quot;https://aviation.stackexchange.com/q/19475/1696&quot;&gt;wing design&lt;/a&gt; will depend on the speeds for which the aircraft is designed. Low aspect ratios and high sweep or delta wings are good for reducing drag at higher speeds. There is no need for very high speeds in a weather observation aircraft, so these would seem to be poor choices. High aspect ratio and low sweep are good for reducing drag at lower speeds, which can maximize endurance. Though endurance is important for weather observation, these designs also have higher wing bending and generally lower top speeds. Both the C-130 and P-8 have moderate aspect ratios and low sweep, which offers a good compromise for strength and efficiency. Jet aircraft fly faster and generally use moderate sweep and aspect ratio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Conventional tails can be more robust&lt;/strong&gt; - T-tails have some issues with &lt;a href=&quot;https://aviation.stackexchange.com/q/1400/1696&quot;&gt;control and stability&lt;/a&gt;, and this prevents them from being used in most cases. The T-tail is mainly useful when the normal position of the horizontal stabilizer is taken up by engines or cargo doors, or would place it too close to wash the engines, or if efficiency is a high priority. Control and stability are particularly important when flying in adverse weather conditions, so if there is no other reason for having a T-tail, a conventional tail works better. All of the aircraft mentioned above have conventional tails.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.643" LastActivityDate="2016-06-02T20:18:23.660" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27976" PostTypeId="1" CreationDate="2016-06-03T01:20:26.580" Score="11" ViewCount="5373" Body="&lt;p&gt;Does the FAA require a minimum distance the between the TDZ of a runway and a public road? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason I ask is because an aircraft landing at a small GA airport (&lt;a href=&quot;http://airnav.com/airport/K68&quot; rel=&quot;noreferrer&quot;&gt;Garnett Municipal, K68)&lt;/a&gt; came across the roadway I was driving on low enough that if I'd been 200 yards up the road he'd have hit my truck. Or at least he'd have had to go around. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N5N4F.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N5N4F.jpg&quot; alt=&quot;runway 19, K68&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the satellite pic you can see that the end of the runway is about 30 feet from the road. The TDZ is about 150 feet. A 3° approach would put you just short of 8' AGL at the road, which is just about exactly how high he was. My truck has a clearance of 10', so it's quite possible to strike vehicles on the road if one is too focused on the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Although it's not a highway (that's about 1000' from the runway), it's the only paved road going east/west for several miles so it gets a bit of traffic&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is it common to put a runway so close to a road? &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="62" LastEditDate="2016-06-03T12:52:04.740" LastActivityDate="2016-08-21T13:48:16.900" Title="Is there a minimum distance between a runway and a public road?" Tags="&lt;faa-regulations&gt;&lt;safety&gt;&lt;runways&gt;" AnswerCount="3" CommentCount="13" ContentLicense="CC BY-SA 3.0" />
  <row Id="27977" PostTypeId="2" ParentId="27976" CreationDate="2016-06-03T01:52:33.683" Score="-3" Body="&lt;p&gt;The FAA regulates aviation and aircraft, not road layout or runway locations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The standard glideslope is three degrees, pretty shallow, so aircraft often travel long distances low above the ground prior to landing. Trees are a big issue. On the island of St. Maarten 747's fly as low as 10-15 feet right over a heavily populated resort beach and pathway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/x6Vff.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/x6Vff.jpg&quot; alt=&quot;KLM 747 coming in for a landing at SXM airport over Maho Beach&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;sup&gt;&lt;strong&gt;Credit: Blick, William E. &lt;a href=&quot;http://www.qsl.net/pj7b/airport.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Princess Juliana International Airport&lt;/a&gt;&lt;/strong&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often there are signs warning of low-flying aircraft so that motorists are not startled.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Don't worry about it too much, planes are way more flimsy than a truck, so as long as the 50 gallons of aviation fuel does not catch on fire or explode, your vehicle will come off much better in the rare event of a collision.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="2143" LastEditDate="2016-08-21T12:31:25.780" LastActivityDate="2016-08-21T12:31:25.780" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="27978" PostTypeId="2" ParentId="27976" CreationDate="2016-06-03T01:57:40.477" Score="7" Body="&lt;p&gt;Yes, there is a minimum area that must be free of obstructions and closed to vehicles, but only for airports that have air carrier operations (see &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=8d6814b39c0ecdd7b08de340ca5e4f9c&amp;amp;mc=true&amp;amp;node=se14.3.139_1309&amp;amp;rgn=div8&quot; rel=&quot;noreferrer&quot;&gt;14 CFR 139.309&lt;/a&gt;) or that receive FAA grants. &lt;a href=&quot;http://www.faa.gov/airports/resources/advisory_circulars/index.cfm/go/document.current/documentnumber/150_5300-13&quot; rel=&quot;noreferrer&quot;&gt;AC 150/5300-13A - &lt;em&gt;Airport Design&lt;/em&gt;&lt;/a&gt; has all the technical details; the actual distances are calculated from formulas, so there's no single answer. If you're really curious, you can read all the gory details in Chapter 3 and &lt;a href=&quot;https://www.faa.gov/airports/southern/airport_safety/runway_safety/media/rsa-tsa-faq.pdf&quot; rel=&quot;noreferrer&quot;&gt;this FAA FAQ&lt;/a&gt; has a (very) simplified explanation:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;What is the size of the RSA [Runway Safety Area]?&lt;/strong&gt;   &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The RSA is a rectangular box surrounding&#xA;  the runway and is based on the runway design code. The dimensions&#xA;  range from 120 feet to 500 feet in width and 240 feet to 1000 feet in&#xA;  length beyond the departure end of the runway. (see FAA Advisory&#xA;  Circular 150/5300-13, Airport Design) Generally, on airports that&#xA;  serve air carrier aircraft, the RSA extends 250 feet either side of&#xA;  the runway centerline and 1000 feet beyond each end of the runway.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You didn't mention which airport you're asking about, but presumably it's either privately owned and/or doesn't receive FAA grant money.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-06-03T02:03:26.040" LastActivityDate="2016-06-03T02:03:26.040" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27979" PostTypeId="2" ParentId="27916" CreationDate="2016-06-03T02:52:26.713" Score="0" Body="&lt;p&gt;Apart from those listed above, some unique aircraft have the horizontal stabilizer attached solid to the vertical stabilizer and then the entire pair pivots around a point on the empennage. The Lockheed Jetstar does this (next time you look at a Jetstar, look for the silver strip of metal below the horiz. stab.) but more commonly, the Mooney M20 series uses this mechanism, illustrated below:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8Jb9D.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8Jb9D.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="15104" LastActivityDate="2016-06-03T02:52:26.713" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27980" PostTypeId="2" ParentId="27823" CreationDate="2016-06-03T04:32:45.947" Score="1" Body="&lt;p&gt;I'm assuming that you are climbing at full power as you're turning left. In this position everything thrust related is essentially creating both left roll and left yaw. Left Yaw in a left bank creates a nose down tendency and may indeed un-coordinate your turn to a point whereas right rudder may be needed which is admittedly cross sticking, BUT IS IT??? Essentially the torque and particularly the P factor may be providing &quot;too much Yaw input&quot; all by itself and the only way to lessen it is to apply right rudder. AKA the p factor and many other &quot;full power&quot; attributes is already adding what is &quot;effectively&quot; &quot;too much&quot; left &quot;rudder input&quot; (even though it's P factor input) and in extreme cases (as is full power and turning left), especially if airspeed begins reducing too, there will be a point whereas the pilot would need right rudder in a left turn. The Ball doesn't lie, step on it!!!&lt;/p&gt;&#xA;" OwnerUserId="15168" LastActivityDate="2016-06-03T04:32:45.947" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27982" PostTypeId="1" AcceptedAnswerId="27983" CreationDate="2016-06-03T06:06:20.163" Score="6" ViewCount="372" Body="&lt;p&gt;Here are some examples I've found on Wikipedia:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Messerschmitt_Me_262&quot;&gt;Me-262&lt;/a&gt;: first flight 1942 July, introduced 1944 April.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19&quot;&gt;MiG-19&lt;/a&gt;: first flight 1953 Sep, introduced 1955 March.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dassault_Mirage_III&quot;&gt;Dassault Mirage III&lt;/a&gt;: first flight 1956 November, introduced 1961.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II&quot;&gt;F-4 Phantom&lt;/a&gt;: first flight 1958 May, introduced 1960 December.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This shows a two or three or even five year gap between the first flight and the entering into mass production.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why such a long gap? What goes on during those years? To me it seems like once the first flight is done, it &quot;works&quot; and the only thing left is some finishing touches. Is it possibly more a matter of setting up a factory?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="1467" LastEditDate="2016-06-03T06:46:17.293" LastActivityDate="2016-06-03T07:23:55.133" Title="Why is there typically a large gap between the first flight and mass production of aircraft?" Tags="&lt;aircraft-design&gt;&lt;military&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="27983" PostTypeId="2" ParentId="27982" CreationDate="2016-06-03T07:23:55.133" Score="7" Body="&lt;p&gt;You don't want an aircraft that just 'works'- rather, you want an aircraft that satisfies your needs. The first flight is usually made by a prototype and does just that- it flies and pretty much nothing else. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Only once you start the flight tests do you understand the airframe limitations and whether the aircraft meets the requirements; usually, a number of modifications are needed. Also, the first flights are rarely, if ever in production configuration. In most of the cases, the required systems are fitted later. In general, most of the combat aircraft bring about substantial improvement over its predecessors- in fact it is a requirement, as the old ones can be used with small improvements at a much lesser cost. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Me 262 was really a revolutionary product and the use of jet engines caused a number of delays; in fact the prototypes were flight tested with piston engines in 1941. The first test flight happened with piston engine- just as well because both the jets flamed out soon after takeoff. By the time the second and third prototypes, the engines had been changed. However, these engines (Jumo 004) were larger, requiring larger nacelles, which in turn required a bigger vertical stabilizer (the landing gear was changed later). Pre-production of Me 262 had started in 1943 (and went nowhere due to engine troubles) when it was decided to change it into a bomber, further increasing the development period. By the time it took the field, it was in too few numbers to do anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another example is the Mirage III. There were significant differences between the aircraft in first flight and the production one. The prototype never reached the required Mach 2 in level flight.The first one to do was the pre-produciotn Mirage IIIA with an engine with more than 30% extra thrust, lengthened fuselage for radar etc. Even this version was not combat capable- that was the Mirage IIIC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The design is not frozen till the flight testing is over and the production plans can only be finalized after that- you never know what'll change (for example the hugely successful Su-27 underwent a change in wing design midway through testing). The delays due to setting up of production comes later and is normally quite less for countries/companies having experience. It is the design freeze that takes up more time during test flights.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-06-03T07:23:55.133" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="27984" PostTypeId="1" CreationDate="2016-06-03T07:24:18.703" Score="11" ViewCount="3536" Body="&lt;p&gt;When I left an A320 today, the fuel truck was already there and refueling the aircraft. (At least, the hose was connected.) Also, a FA said they will fly back within 40 minutes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This isn't much time, and I wonder if they start to refuel the aircraft before actually calculating the required amount. (Since it's a 4h flight, they'll need quite some fuel.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So I'd like to know how much time is needed for flight planning of an airliner. Maybe some planning for the next flight can already be done in advance during the current flight? Maybe some part can already be done by others?  Or does the entire process take just a few minutes today?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's also not clear to me what is done during flight planning. Of course planning the route, including possible ways to divert the aircraft, and amount of fuel. What else?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT:&lt;/strong&gt; To make it more clear: I'm asking about the work the pilots have to do to prepare for the next flight&lt;/p&gt;&#xA;" OwnerUserId="4170" LastEditorUserId="1696" LastEditDate="2016-06-03T15:26:39.650" LastActivityDate="2016-06-04T14:16:43.493" Title="How long does flight planning take / when is it done / how is it done?" Tags="&lt;airline-operations&gt;&lt;flight-planning&gt;" AnswerCount="3" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27985" PostTypeId="2" ParentId="27972" CreationDate="2016-06-03T08:59:36.700" Score="8" Body="&lt;p&gt;A number of 737s are fitted with forward airstairs (and aft ones too). The Boeing Airplane Planning Document gives the airstairs opening as 0.41 X 1.12m, while the airstairs can be folded to less than 2.5m length. This should give the volume occupied by the airstairs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/sy2t0.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/sy2t0.png&quot; alt=&quot;Airstair&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from Boeing 737 &lt;a href=&quot;http://www.google.co.in/url?sa=t&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=web&amp;amp;cd=11&amp;amp;ved=0ahUKEwiu2sa0vIvNAhWHVZQKHXiMCFMQFghSMAo&amp;amp;url=http%3A%2F%2Fwww.boeing.com%2Fassets%2Fpdf%2Fcommercial%2Fairports%2Facaps%2F737.pdf&amp;amp;usg=AFQjCNEoss0uTBwrNUe9HIQDVLCpBWxBAA&amp;amp;bvm=bv.123664746,d.dGo&amp;amp;cad=rja&quot; rel=&quot;noreferrer&quot;&gt;Airplane Characteristics for Airport Planning&lt;/a&gt; document.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;According to an article in &lt;a href=&quot;http://www.aviationpros.com/article/10388532/dc9-md80-737-airstairs-the-forgotten-ones&quot; rel=&quot;noreferrer&quot;&gt;aviationpros&lt;/a&gt;, the total system weighs in around 200 lbs:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Aircraft such as the DC9, MD80, MD90, and 737 aircraft have had a long enough history that many of them were built with the forward passenger air stair assembly. Many aircraft were also converted to non-airstair versions Ñ a 200+ lb. weight savings for the operator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2016-06-03T12:30:26.920" LastActivityDate="2016-06-03T12:30:26.920" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27986" PostTypeId="2" ParentId="27952" CreationDate="2016-06-03T09:22:18.250" Score="5" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Would slamming down the plane really hard (maybe even nose down) given a more realistic scenario and more valuable data rather than making it soft?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Gone, everything is gone then. What are you going to try to improve from the outcome of such a test? Forget the real airplanes I have never been able to salvage a model aircraft that crashed nose down for any reason whatsoever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have on many times crash landed a model safely that had its landing gear malfunction and that's the practice that gives you valuable lessons for future landings. If you had an airplane without a landing gear and you wanted to study how can you improve chances of its survivability you would want to make a survivable attempt in the first place. You wouldn't want to crash it hard deliberately and then try to pick up pieces of the landing gear to find out what could you have done better.&lt;/p&gt;&#xA;" OwnerUserId="1048" LastActivityDate="2016-06-03T09:22:18.250" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27988" PostTypeId="2" ParentId="27936" CreationDate="2016-06-03T10:32:54.960" Score="3" Body="&lt;p&gt;LiveATC is probably your best shot. The quality you'll get on the stream depends on where the receiver is setup. Since aircraft communications are in VHF or UHF (military) reception is basically within line-of-sight range. This is why often you'll hear the aircraft side of the conversation without hearing ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would just browse the various streams on LiveATC until you find a good one. OR, if you're near an airport, set up your own receiver!&lt;/p&gt;&#xA;" OwnerUserId="15218" LastActivityDate="2016-06-03T10:32:54.960" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27989" PostTypeId="2" ParentId="27984" CreationDate="2016-06-03T10:57:18.403" Score="18" Body="&lt;p&gt;The pilots don't do the flight planning. It is done 1-2 hours before the flight by dispatchers using computer software.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On a quick turnaround, one pilot goes to a printer to retrieve the flight plan. The other stays with the aircraft and prepares for the next flight.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sometimes someone will bring the flight plan directly to the aircraft. Some airlines have stopped using paper flight plans and instead download to an iPad. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots review the flight plan to ensure it meets all requirements, and can request a reroute, or additional fuel it they feel it is needed.  &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-06-04T12:23:27.810" LastActivityDate="2016-06-04T12:23:27.810" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="27991" PostTypeId="1" AcceptedAnswerId="27992" CreationDate="2016-06-03T13:33:39.490" Score="9" ViewCount="3917" Body="&lt;p&gt;The HondaJet has over wing mounted engines as can be seen here:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HZw1L.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HZw1L.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Image from &lt;a href=&quot;http://luxurylaunches.com&quot; rel=&quot;nofollow noreferrer&quot;&gt;LuxuryLaunches.com&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The advantages v drawbacks of the over wing mount have been discussed &lt;a href=&quot;https://aviation.stackexchange.com/questions/9680/why-not-mount-airliner-jet-engines-above-the-wings&quot;&gt;here&lt;/a&gt; and &lt;a href=&quot;https://aviation.stackexchange.com/questions/1397/how-does-the-mounting-location-of-a-jet-engine-affect-aircraft-performance&quot;&gt;here&lt;/a&gt;. The over wing mount on the HondaJet &lt;em&gt;could&lt;/em&gt; take advantage of the &lt;a href=&quot;http://en.wikipedia.org/wiki/Coand%C4%83_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;Coandă effect&lt;/a&gt;, except that they're not &lt;em&gt;in front&lt;/em&gt; of the wing, as can be seen (above), but more clearly here:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/r7oX5.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/r7oX5.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Sourced from &lt;a href=&quot;https://www.hondajet.com/gallery-and-downloads&quot; rel=&quot;nofollow noreferrer&quot;&gt;HondaJet.com&lt;/a&gt; themselves.&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;In fact, the placement looks like the typical rear fuselage mount, except they're not mounted to the fuselage. The rear fuselage mount is quite common in the small private/luxury jet market:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WXM9J.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WXM9J.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Gulfstream G550 hosted by &lt;a href=&quot;https://www.gulfstreamnews.com/photo/album?id=5085aae329371a4f7d004a9f&amp;amp;p=1000&amp;amp;s=order&amp;amp;t=photo&quot; rel=&quot;nofollow noreferrer&quot;&gt;Gulfstream&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wIFgX.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wIFgX.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&#xA;&lt;br&gt;&lt;sup&gt;Learjet 45 image from &lt;a href=&quot;http://aviation-times.aero/bombardier-highlights-significant-progress-on-its-new-learjet-aircraft-programs/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aviation-Times.aero&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;This seems to combine all the disadvantages of an over wing mount with the disadvantages of a rear fuselage mount, and neither of those positions seem to have a huge amount of advantages.&lt;/p&gt;&#xA;&lt;h2&gt;What are the advantages of a high, over/behind wing engine mounting position as seen in the HondaJet?&lt;/h2&gt;&#xA;" OwnerUserId="5517" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-04-20T07:47:42.697" Title="What advantage(s) are there for the HondaJet's engine mount position?" Tags="&lt;aircraft-design&gt;&lt;engine-placement&gt;&lt;hondajet&gt;" AnswerCount="4" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="27992" PostTypeId="2" ParentId="27991" CreationDate="2016-06-03T14:28:25.637" Score="9" Body="&lt;p&gt;Probably the reasons are similiar to the reasons which lead to the same mounting on the &lt;a href=&quot;https://en.wikipedia.org/wiki/VFW-Fokker_614&quot;&gt;VFW-Fokker 614&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;This arrangement was used to avoid the structural weight penalties of rear mounted engines and the potential ingestion problems of engines mounted under the wings. This allowed a short and sturdy undercarriage, specially suited for operations from poorly prepared runways.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;// Update  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The space in the cabin should be the &lt;a href=&quot;http://www.hondajet.com/Content/pdf/FlightInternational_CoverStory.pdf&quot;&gt;actual&lt;/a&gt; reason in this case.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;“I had the idea around 1996,” says Fujino. “The cost of a business jet is very high. To reduce the cost, you have to reduce the size of the aircraft, but then you sacrifice comfort. I wanted to make the aircraft smaller, but not sacrifice the cabin.” &lt;strong&gt;Most business jets have the engines mounted on the rear&#xA;  fuselage, and moving the structure and systems to support the engines out of the fuselage would maximise space inside the cabin without increasing the size of the aircraft, he believed.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As always, there are pro and cons:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The problem with an overwing engine is&#xA;  that interference between the nacelle and&#xA;  wing can accelerate the airflow and cause&#xA;  &lt;strong&gt;a strong shockwave&lt;/strong&gt;, reducing the drag&#xA;  rise Mach number – the airspeed at which&#xA;  shockwaves form and drag begins to rise&#xA;  rapidly. Fujino says computational analysis&#xA;  and windtunnel testing enabled Honda to&#xA;  find a “sweet spot”, &lt;strong&gt;an overwing engine&#xA;  location that minimises the shockwave.&lt;/strong&gt;&#xA;  The result, he says, is a 5% better lift-to-&#xA;  drag ratio – aerodynamic efficiency – in the&#xA;  cruise than a rear-engined aircraft.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="1084" LastEditorUserId="5517" LastEditDate="2016-06-03T14:50:08.783" LastActivityDate="2016-06-03T14:50:08.783" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27993" PostTypeId="2" ParentId="27984" CreationDate="2016-06-03T15:20:31.820" Score="10" Body="&lt;p&gt;&lt;strong&gt;When is flight planning done?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anytime convenient! Honestly. You can plan for a trip 3 hours later, tomorrow, next week, or even next month. There're already pre-defined airways on most areas you'll fly above; you just need to lookup the charts and select yourself a route.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, unlike a family road trip, commercial flights are flown everyday. Every pilot assigned to the flight will make that trip. So, no, pilots do not arrive at the gate, being told &quot;&lt;em&gt;Your next hop is going to Hawaii&lt;/em&gt;&quot;, then grab the charts, lay them out on a nice big table, and figure out which waypoints to go. Somebody at the company has already done that for them. That somebody is called a dispatcher.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And remember, it's the same route flown over and over again, day by day. You only have to plan once.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;When do I know how much fuel to take?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To figure that out, you need to know how much cargo and how many passengers are going on this flight. When will you know that? A few hours before departure, you already have a good estimate (given that usually x% of passengers will turn up). By the time check-in for this flight is closed, you have the exact number. Just plug in that number into a calculator and you'll get your fuel requirement. Even without computers, this calculation takes only a minute.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Pilots' responsibility&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots (in particular the captain) has the final and unquestionable authority over any matter of the flight, including its flight plan. That said, pilots are not the ones who come up with the initial plan. In airline operations, the pilots' responsibility is to adjust the plan as necessary. For example, if bad weather is expected at the destination, the captain might request extra contingency fuel.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So in short, the pilots' responsibility include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Familiar themselves with the planned route&lt;/li&gt;&#xA;&lt;li&gt;Review the weather forecast and NOTAMs, and adjust the flight plan if necessary&lt;/li&gt;&#xA;&lt;li&gt;Verify the weight and balance is appropriate (taking into consideration cargo, fuel and passengers. Again, somebody has already done the calculation for them.)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;That's not much, indeed.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="3386" LastEditDate="2016-06-04T14:16:43.493" LastActivityDate="2016-06-04T14:16:43.493" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="27994" PostTypeId="2" ParentId="27921" CreationDate="2016-06-03T15:50:37.437" Score="8" Body="&lt;p&gt;&lt;strong&gt;They don't handle that uncertainty.&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Safety is always the prominent factor in the aviation industry. That said, measurements need only to be &quot;accurate enough&quot; for the purpose of safety. Being off by small amount would not compromise safety.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Furthermore, the atmospheric condition is always different; it is so dynamic and cannot be precisely measured. As long as the measurement is &lt;em&gt;accurate enough&lt;/em&gt;, the aircraft will fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Theoretically, you could argue that there's a chance:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;calculated weight is already at MTOW&lt;/li&gt;&#xA;&lt;li&gt;every passenger happens to weight way above average&lt;/li&gt;&#xA;&lt;li&gt;they all bought a lot of souvenir at the airport shops&lt;/li&gt;&#xA;&lt;li&gt;density altitude was extraordinary high&lt;/li&gt;&#xA;&lt;li&gt;a 10 knots tailwind was present at takeoff&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and the aircraft overrun the runway during its takeoff roll. However, such a chance is so small that we accept our current method as it is and expect the aircraft to tolerate that uncertainly within its designed safety factors.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Such believe was found to be wrong when &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_Midwest_Flight_5481&quot; rel=&quot;noreferrer&quot;&gt;a small aircraft crashed on takeoff in 2003&lt;/a&gt;. Regulations were then modified so that on a small enough aircraft, the actual weight of each passenger (plus luggage) must be used, rather than using a standard weight for estimation.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-06-03T15:50:37.437" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27996" PostTypeId="1" AcceptedAnswerId="29024" CreationDate="2016-06-03T17:47:38.413" Score="6" ViewCount="878" Body="&lt;p&gt;Does a jet engines air intake count to the overall jets geometry dependent air resistance?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Taking the &lt;a href=&quot;https://en.wikipedia.org/wiki/Saab_29_Tunnan&quot; rel=&quot;nofollow&quot;&gt;Saab Tunnan&lt;/a&gt; as an example it's overall air resistance has to be quite low because of it's huge air inlet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or does the inlet create air resistance as well but just not so much?&lt;/p&gt;&#xA;" OwnerUserId="15244" LastEditorUserId="1696" LastEditDate="2016-06-23T17:03:18.217" LastActivityDate="2016-06-23T17:03:18.217" Title="Does the air resistance of a jet engine air intake count towards the jet's total air resistance?" Tags="&lt;aerodynamics&gt;&lt;jet-engine&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="27998" PostTypeId="1" AcceptedAnswerId="27999" CreationDate="2016-06-03T19:58:26.493" Score="22" ViewCount="1831" Body="&lt;p&gt;I have seen photos of hot air balloons aloft with fearsome looking burners shooting flames into the interior of the balloon. That may be fine for a fully inflated balloon. But what about when the balloon is in a heap on the ground? How do you get it inflated without burning the fabric?&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-06-04T12:36:02.253" Title="How do hot air balloons get started (without burning the fabric)?" Tags="&lt;takeoff&gt;&lt;balloon&gt;" AnswerCount="1" CommentCount="3" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="27999" PostTypeId="2" ParentId="27998" CreationDate="2016-06-03T20:50:22.833" Score="33" Body="&lt;p&gt;The balloon is spread out on the ground and rigged to the basket.&#xA;Then, a cold air blower is used to do the initial inflation, blowing air into the envelope through the bottom aperture. This gets the balloon about 75% inflated, but still horizontal.&#xA;Lastly, the burners are lit to heat the cold air already inside the canopy, expanding it and raising the balloon to vertical and full inflation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can find any number of videos on YouTube that show the process. Here's one: &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/aetVZJfTyX4?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="15245" LastEditorUserId="-1" LastEditDate="2016-06-04T12:36:02.253" LastActivityDate="2016-06-04T12:36:02.253" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28002" PostTypeId="1" CreationDate="2016-06-04T02:49:24.397" Score="15" ViewCount="1526" Body="&lt;p&gt;I'm licensed to fly multi-engine aircraft. I currently fly the &lt;a href=&quot;https://en.wikipedia.org/wiki/Diamond_DA42&quot;&gt;DA-42NG&lt;/a&gt;. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, nowhere in my training and in the official POH was I introduced to procedures for handing a dual-engine failure in-flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There's no mention of a Best Glide Speed whatsoever.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm assuming this is the case for most, or maybe all GA Twin-Engine airplanes. I know jets can glide for some time without any power. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Question is - can GA airplanes? I know it won't fall like a rock - but there's got to be some science to follow here, right? Why haven't the manufactures mentioned it even once? Why isn't it part of the training?&lt;/p&gt;&#xA;" OwnerUserId="11136" LastEditorUserId="3201" LastEditDate="2016-06-04T10:42:21.513" LastActivityDate="2019-12-03T10:14:08.570" Title="Why isn't there a procedure for dual-engine failure in twin-engine airplanes?" Tags="&lt;faa-regulations&gt;&lt;general-aviation&gt;&lt;usa&gt;&lt;engine-failure&gt;&lt;multi-engine&gt;" AnswerCount="2" CommentCount="10" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="28003" PostTypeId="2" ParentId="28002" CreationDate="2016-06-04T03:08:22.627" Score="10" Body="&lt;p&gt;There are.  The Metroliner (SA227) has a dual flameout checklist.  It's possible that the company I flew for developed their own and had it approved, but we DID have a checklist for that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I think they're rare on pistons twins because there are a very limited number of environmental factors that can cause double engine failures.  It's also possible to simply run out of gas.*  A turbine can ingest water, ice, dust, sand, snow, etc (no filters) that can contribute to a flameout.  The factor that causes one to quit will likely effect the other in a similar way.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I do know a pilot who flamed out both engines by using engine inlet heat on both engines at the same time.  The ice melted off the inlets at about the same time, both engines ingested the ice, and they quit.  He managed to relight both of them and landed uneventfully.  That likely would not happen in a piston twin.  The alt air doors would open and keep the engines running.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;*If you find yourself thinking &quot;I'm going to need that double engine failure checklist in about 20mins,&quot; you should probably seriously reflect upon the decisions you made throughout the flight.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="11201" LastEditDate="2016-06-04T17:12:06.410" LastActivityDate="2016-06-04T17:12:06.410" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="28004" PostTypeId="1" CreationDate="2016-06-04T03:22:05.707" Score="3" ViewCount="7908" Body="&lt;p&gt;After landing, which speed shall we use to exit from high speed taxiway? Max. 60 knots ground speed or indicated air speed?&lt;/p&gt;&#xA;" OwnerUserId="15251" LastActivityDate="2016-06-08T09:20:40.417" Title="Which speed shall be used on high speed taxiway?" Tags="&lt;taxiing&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-06-08T16:51:45.263" ContentLicense="CC BY-SA 3.0" />
  <row Id="28005" PostTypeId="1" CreationDate="2016-06-04T04:54:28.640" Score="4" ViewCount="1476" Body="&lt;p&gt;Are there any guidelines or rules of thumb about when airframes become affected by metal fatigue?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More specifically, is something like a 1950s vintage Cessna still safe, or should I be worried about metal fatigue? I'm thinking of buying and completely overhauling a C172, but how can I determine if I should be concerned about metal fatigue or not? The planes are so old, and it doesn't seem possible to me that their structure has not been compromised because of their age.&lt;/p&gt;&#xA;" OwnerUserId="15252" LastEditorUserId="62" LastEditDate="2016-06-04T18:11:47.303" LastActivityDate="2016-06-05T08:42:30.533" Title="Are there any guidelines on airframe age and metal fatigue in light aircraft?" Tags="&lt;safety&gt;&lt;general-aviation&gt;&lt;aircraft-maintenance&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="28006" PostTypeId="2" ParentId="28004" CreationDate="2016-06-04T07:28:24.760" Score="14" Body="&lt;p&gt;According to the ICAO manual on Aerodrome Standards (based on Annex 14) &lt;a href=&quot;http://www.icao.int/safety/implementation/library/manual%20aerodrome%20stds.pdf&quot;&gt;(link)&lt;/a&gt; - maximum 35 knots for code 1 and 2 runways, and maximum 50 knots for code 3 and 4 runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since you are moving &lt;strong&gt;on the ground&lt;/strong&gt;, it makes sense to use your &lt;strong&gt;ground speed&lt;/strong&gt; as reference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I imagine most aircraft operators have procedures for using rapid exit taxiways in their standard operating manuals. As a result, the actual speed used by air crews is likely to vary depending on which company they fly for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;IFALPA recommends that you slow down to normal taxi speed on the runway, and then use rapid exit taxiways with normal taxi speed (as opposed to the very low speed you would need to use to turn off the runway using a pendicular taxiway). &lt;a href=&quot;http://www.ifalpa.org/downloads/Level1/Safety%20Bulletins/Airport%20Issues/07SAB012%20-%20Misuse%20of%20rapid%20exit%20taxiways.pdf&quot;&gt;(link)&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the ICAO manual:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;3.8.15&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A rapid exit taxiway shall be designed with a radius of turn-off curve of at least: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;550 m where the code number is 3 or 4; and &lt;/li&gt;&#xA;  &lt;li&gt;275 m where the code number is 1 or 2; &lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;  &#xA;  &lt;p&gt;to enable exit speeds under wet conditions of: &lt;/p&gt;&#xA;  &#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;93 km/h where the code number is 3 or 4; and &lt;/li&gt;&#xA;  &lt;li&gt;65 km/h where the code number is 1 or 2.&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Note: you can find the definitions of the code numbers (1, 2, 3, 4) on page 17 of the manual to which I linked above.&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-06-04T07:28:24.760" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="28007" PostTypeId="1" AcceptedAnswerId="29082" CreationDate="2016-06-04T11:11:43.373" Score="4" ViewCount="1574" Body="&lt;p&gt;Common documentation easily found online (using A320 family as an example):&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://fr.scribd.com/doc/36100929/Aircraft-Manual-Airbus-A330-Flight-Crew-Operating-Manual-Vol2&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight crew operating manual&lt;/a&gt; (FCOM, multiple volumes)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://fr.scribd.com/doc/249804121/AIRBUS-A320-Flight-Crew-Training-Manual&quot; rel=&quot;nofollow noreferrer&quot;&gt;Flight crew training manual&lt;/a&gt; (FCTM)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://fr.scribd.com/doc/104395824/A-320-Standards-Operating-Procedures-Manual-Vietnam-Airlines&quot; rel=&quot;nofollow noreferrer&quot;&gt;Standard operating procedures&lt;/a&gt; (SOP)&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://fr.scribd.com/doc/314464077/Airbus-A319-A320-A321-Quick-Reference-Handbook&quot; rel=&quot;nofollow noreferrer&quot;&gt;Quick reference handbook&lt;/a&gt; (QRH)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZV2Jj.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZV2Jj.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.nycaviation.com/2014/03/youre-pilot-flight-medical-emergency/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are they used for? What are the other major documents necessary to fly? Do they differ with manufacturers or airlines? Are they available on paper or display?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-06-04T11:26:25.947" LastActivityDate="2016-06-07T15:44:39.673" Title="What is the structure of the crew documentation used in flight for a commercial aircraft?" Tags="&lt;airline-operations&gt;&lt;airline-pilot&gt;&lt;aircraft-manufacturer&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="28008" PostTypeId="2" ParentId="28005" CreationDate="2016-06-04T12:49:14.820" Score="4" Body="&lt;p&gt;The short answer is no, age or airframe hours alone are not something to be concerned about on these light Cessnas.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A 1975 C172M I flew for work had about 20,000 hours, or more, on the airframe (can't remember exactly), largely in low level flight at or below 500 ft AGL, often in high winds, moderate turbulence, low level wind shear, etc., and flight including plenty of relatively high G maneuvering, and lots of crosswind landings far exceeding the demonstrated crosswind component. Years ago, before my employer bought it, someone managed to flip it over on it's back while taxiing. The thing has also had several bird strikes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an A&amp;amp;P mechanic, I have thoroughly inspected this airframe, to the level of an annual/100 hr inspection. Keeping in mind the airframe's age and history, my inspections included paying special attention to items of structural interest such as spar and strut attach points, control surface attach points, firewall, spars, etc. I have no concerns about the structure of this particular airframe, and I've trusted my life to it over 840 flight hours.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have quite a bit of experience maintaining a number of single engine Cessna models, including quite a number of older, well worn individuals. I cannot recall encountering any structural issues that were due to metal fatigue alone. Most of the structural instances I can think of would be due to one time events such as a hard landing causing a firewall to wrinkle or crack. Some, such as cracked gear strut castings—in a U206G for example—are relatively common on such airframes that are used for rough, backcountry flying. I suppose that could be chalked up to a type of metal fatigue, but I don't think it is what you are concerned about with this question. Such items are a known issue and won't cause you to fall out of the sky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The real age-related concerns regarding structural issues will be corrosion. Obviously, corrosion can occur over a short time frame, but give an airframe an extended stay in a harsh, corrosion conducive environment and it may fare more poorly than in a &quot;good&quot; environment. That being said, there are plenty of great airframes from the '50-'70s that have been hangered or sitting in barns in humid climates that are in excellent shape. The same will probably not be true of the engines if they sat unused, but the airframes may be in great shape.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Every airframe is different, and a thorough pre-buy inspection will be necessary to ensure that yours does not suffer from some major structural issue. But age and hours alone should not be of real concern.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would not hesitate to buy a high-time, vintage Cessna airframe merely on account of those factors.&lt;/p&gt;&#xA;" OwnerUserId="12720" LastEditorUserId="12720" LastEditDate="2016-06-04T13:59:53.550" LastActivityDate="2016-06-04T13:59:53.550" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28009" PostTypeId="1" CreationDate="2016-06-04T13:34:57.803" Score="15" ViewCount="5043" Body="&lt;p&gt;Are the new systems of today built with the same CPUs and programming languages and development software as those of 20 or more years ago?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By &lt;em&gt;new&lt;/em&gt; I mean that these systems are currently being designed for future airliners, or have seen service for the first time recently.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any specific examples of new designs as used in a major latest-generation airliner (the A350 and 787 be the most obvious examples) would be better than general answers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm interested in examples from any flight-essential systems (but not, for example, on-board entertainment).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As part of this question: does the industry tend to update its products through incremental updates to the microprocessors and programming languages it adopts, or does it tend to make once-in-a-generation shifts to new technologies? And, are there significant differences in the way airline manufacturers (as opposed to military/general aviation industries) approach this?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="14197" LastEditDate="2016-06-09T00:08:18.123" LastActivityDate="2017-12-03T02:34:39.967" Title="Which CPUs and programming languages are used in new airliner flight control systems?" Tags="&lt;avionics&gt;&lt;autopilot&gt;&lt;software&gt;&lt;fly-by-wire&gt;" AnswerCount="2" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28010" PostTypeId="2" ParentId="27984" CreationDate="2016-06-04T14:06:44.253" Score="0" Body="&lt;p&gt;Well, a 40 minute turnaround time can be quite short to leave time for planning.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Mind you it's not just about choosing an appropriate flight route, but weather considerations, reading Notams, winds, choosing an appropriate flight level, deciding on extra fuel, choosing takeoff alternates, en-route alts, destinations alts, then the w/x and Notams for those alternates, etc.  It can probably be done in 30 minutes , but it will be hairy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Normally all my sectors (legs?) are pre-planned/read/briefed at the beginning of a work day. Deciding on most important factors before we even go to the plane.  Then, when we have to do a 40' (30'?) turnaround it makes it all much easier. Most times we can call ground handling companies via VHF before we even land, informing them in advance of the services we need (including the amount of refuelling).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How long does flight planning take&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Computers print an OFP in probably under 1 minute. Then maybe 5-10 minutes for the pilots to read/change/understand/brief.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;when is it done&lt;/strong&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the beginning of the work day&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;how is it done?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;uhm.. see above&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;I'm asking about the work the pilots have to do to prepare for the next flight&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ok, different question as it is not so much planning related: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Refuel&lt;/li&gt;&#xA;&lt;li&gt;walk-around check&lt;/li&gt;&#xA;&lt;li&gt;prepare the FMC (in one way or another)&lt;/li&gt;&#xA;&lt;li&gt;review the mass&amp;amp;balance loadsheet&lt;/li&gt;&#xA;&lt;li&gt;compute takeoff speeds&lt;/li&gt;&#xA;&lt;li&gt;review and brief the departure &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;and you are good to do. Did I forget anything?&lt;/p&gt;&#xA;" OwnerUserId="419" LastEditorUserId="419" LastEditDate="2016-06-04T14:14:44.140" LastActivityDate="2016-06-04T14:14:44.140" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="28011" PostTypeId="1" AcceptedAnswerId="28015" CreationDate="2016-06-04T15:50:27.693" Score="4" ViewCount="352" Body="&lt;p&gt;I hold a sport pilot certificate and a valid third class medical. I'm pursuing a private pilot certificate and receiving training in C172's and C182's, though I also have access to a C162. I was wondering if I can be signed off to solo in the non-LSA aircraft without going through the process of obtaining a student pilot certificate, and just getting the logbook endorsement as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;I certify that (First name, MI, Last name) has received the required presolo training in a (make and model aircraft). I have determined he/she has demonstrated the proficiency of FAR 61.87(d) and is proficient to make solo flights in (make and model aircraft). &#xA;  4/25/14 J. J. Jones 987654321CFI Exp. 12/31/05&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I have several solo missions that could benefit from additional power and useful load provided by the larger aircraft, but with the new student pilot certification process, I'm wondering if it's worth the hassle.&lt;/p&gt;&#xA;" OwnerUserId="15261" LastEditorUserId="62" LastEditDate="2016-06-04T18:14:22.490" LastActivityDate="2016-06-04T19:35:28.800" Title="Upgrading a Sport license to a Private license - is a new student license necessary to solo non-LSA aircraft?" Tags="&lt;faa-regulations&gt;&lt;flight-training&gt;&lt;student-pilot&gt;&lt;light-sport-aircraft&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="28012" PostTypeId="2" ParentId="28007" CreationDate="2016-06-04T15:56:07.550" Score="2" Body="&lt;p&gt;The documents legally required on-board differ by jurisdiction. I can only speak to the case here in the US which falls under the FAA. If the flight is between two jurisdictions there may be local regulations to comply with at your destination as well. For example if leaving the US all onboard must have their passports as well as any pertinent custom forms.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are they used for?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Generally these documents are all used for reference. Here in the US its generally forbidden to read personal material in the cockpit however the pilots are free to read documentation relating to the aircraft and operations. They may chose to use time in flight to read up on things.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These documents also include emergency procedures that the crew may need to use in the event of a failure.   &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;What are the other major documents necessary to fly?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Aside from what the plane needs the crew must also have current medical certificates and pilots license on their persons.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If we take a look at &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=c422e9ffb37f43ed89bfef56558f4f1f&amp;amp;mc=true&amp;amp;node=se14.3.121_1153&amp;amp;rgn=div8&quot; rel=&quot;nofollow&quot;&gt;FAR 121.135&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;(a) Except as provided in paragraph (c) of this section, no&#xA;  certificate holder may operate an aircraft unless that aircraft— &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1)&#xA;    Is registered as a civil aircraft of the United States and &lt;strong&gt;carries an&#xA;    appropriate current airworthiness certificate issued under this&#xA;    chapter&lt;/strong&gt;; and &lt;/p&gt;&#xA;    &#xA;    &lt;p&gt;(2) Is in an airworthy condition and meets the applicable&#xA;    airworthiness requirements of this chapter, including those relating&#xA;    to identification and equipment. &lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;(b) A certificate holder may use an&#xA;  approved weight and balance control system based on average, assumed,&#xA;  or estimated weight to comply with applicable airworthiness&#xA;  requirements and operating limitations. &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) A certificate holder may&#xA;  operate in common carriage, and for the carriage of mail, a civil&#xA;  aircraft which is leased or chartered to it without crew and is&#xA;  registered in a country which is a party to the Convention on&#xA;  International Civil Aviation if— &lt;/p&gt;&#xA;  &#xA;  &lt;blockquote&gt;&#xA;    &lt;p&gt;(1) &lt;strong&gt;The aircraft carries an&#xA;    appropriate airworthiness certificate issued by the country of&#xA;    registration and meets the registration and identification&#xA;    requirements of that country&lt;/strong&gt;; &#xA;    (2) The aircraft is of a type design&#xA;    which is approved under a U.S. type certificate and complies with all&#xA;    of the requirements of this chapter (14 CFR Chapter 1) that would be&#xA;    applicable to that aircraft were it registered in the United States,&#xA;    including the requirements which must be met for issuance of a U.S.&#xA;    standard airworthiness certificate (including type design conformity,&#xA;    condition for safe operation, and the noise, fuel venting, and engine&#xA;    emission requirements of this chapter), except that a U.S.&#xA;    registration certificate and a U.S. standard airworthiness certificate&#xA;    will not be issued for the aircraft; &#xA;    (3) The aircraft is operated by&#xA;    U.S.-certificated airmen employed by the certificate holder; and (4)&#xA;    The certificate holder files a copy of the aircraft lease or charter&#xA;    agreement with the FAA Aircraft Registry, Department of&#xA;    Transportation, 6400 South MacArthur Boulevard, Oklahoma City, OK&#xA;    (Mailing address: P.O. Box 25504, Oklahoma City, OK 73125).&lt;/p&gt;&#xA;  &lt;/blockquote&gt;&#xA;  &#xA;  &lt;p&gt;Do they differ with manufacturers or airlines?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Airlines may publish excess documentation and checklists that meet or exceed the manufacture specifications this some airlines may have slightly varying procedures. Aircraft makers must publish documentation for the aircraft that includes its operational limitations you can find a &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title14/14cfr23_main_02.tpl&quot; rel=&quot;nofollow&quot;&gt;good chunk of the regulations in the FAR's here&lt;/a&gt;. Specifically, &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;&lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=a1f9b33a0b28aaba60b03e25edbaab21&amp;amp;mc=true&amp;amp;node=sg14.1.23_11567.sg47&amp;amp;rgn=div7&quot; rel=&quot;nofollow&quot;&gt;§23.1581   General.&lt;/a&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Furnishing information. An Airplane Flight Manual must be&#xA;  furnished with each airplane, and it must contain the following:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(1) Information required by §§23.1583 through 23.1589.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) Other information that is necessary for safe operation because of&#xA;  design, operating, or handling characteristics.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Further information necessary to comply with the relevant&#xA;  operating rules.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Approved information. (1) Except as provided in paragraph (b)(2)&#xA;  of this section, each part of the Airplane Flight Manual containing&#xA;  information prescribed in §§23.1583 through 23.1589 must be approved,&#xA;  segregated, identified and clearly distinguished from each unapproved&#xA;  part of that Airplane Flight Manual.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(2) The requirements of paragraph (b)(1) of this section do not apply&#xA;  to reciprocating engine-powered airplanes of 6,000 pounds or less&#xA;  maximum weight, if the following is met:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(i) Each part of the Airplane Flight Manual containing information&#xA;  prescribed in §23.1583 must be limited to such information, and must&#xA;  be approved, identified, and clearly distinguished from each other&#xA;  part of the Airplane Flight Manual.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(ii) The information prescribed in §§23.1585 through 23.1589 must be&#xA;  determined in accordance with the applicable requirements of this part&#xA;  and presented in its entirety in a manner acceptable to the&#xA;  Administrator.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(3) Each page of the Airplane Flight Manual containing information&#xA;  prescribed in this section must be of a type that is not easily&#xA;  erased, disfigured, or misplaced, and is capable of being inserted in&#xA;  a manual provided by the applicant, or in a folder, or in any other&#xA;  permanent binder.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) The units used in the Airplane Flight Manual must be the same as&#xA;  those marked on the appropriate instruments and placards.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(d) All Airplane Flight Manual operational airspeeds, unless otherwise&#xA;  specified, must be presented as indicated airspeeds.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(e) Provision must be made for stowing the Airplane Flight Manual in a&#xA;  suitable fixed container which is readily accessible to the pilot.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(f) Revisions and amendments. Each Airplane Flight Manual (AFM) must&#xA;  contain a means for recording the incorporation of revisions and&#xA;  amendments.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;Are they available on paper or display?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Depends on the carrier, a great deal of movement to iPads and the such has seen the digitization of many things.   &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-06-04T22:48:25.903" LastActivityDate="2016-06-04T22:48:25.903" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28014" PostTypeId="1" CreationDate="2016-06-04T18:47:11.583" Score="9" ViewCount="12273" Body="&lt;p&gt;I couldn't find any official comparison for noise level (dB) in Airbus A380 versus the Boeing 777 300 ER. Does anyone have some info about it? Which one is better in terms of acoustic isolation?&lt;/p&gt;&#xA;" OwnerUserId="15266" LastEditorUserId="487" LastEditDate="2016-06-21T18:53:40.813" LastActivityDate="2020-06-14T10:24:46.283" Title="How do the cabin noise levels of the A380 and the 777 300 ER compare?" Tags="&lt;airbus-a380&gt;&lt;noise&gt;&lt;boeing-777&gt;&lt;cabin&gt;" AnswerCount="7" CommentCount="2" FavoriteCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="28015" PostTypeId="2" ParentId="28011" CreationDate="2016-06-04T19:35:28.800" Score="6" Body="&lt;p&gt;You do not need to get another student pilot certificate.  The endorsement you need is not for student pilots.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;strong&gt;70. To act as PIC of an aircraft in solo operations when the pilot does not hold an appropriate category/class rating: § 61.31(d)(2).&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;I certify that (First name, MI, Last name) has received the training as required by § 61.31(d)(2) to serve as a PIC in a (specific category and class of aircraft). I have determined that he/she is prepared to serve as PIC in that (make and model) aircraft. Limitations: (optional).&#xA;/s/ [date] J. J. Jones 987654321CFI Exp. 12-31-19&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;The answer lies in &lt;a href=&quot;http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_61-65F.pdf&quot; rel=&quot;noreferrer&quot;&gt;Advisory Circular 61-65&lt;/a&gt;.  Version F is the latest.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-06-04T19:35:28.800" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28016" PostTypeId="1" CreationDate="2016-06-04T19:41:06.503" Score="3" ViewCount="233" Body="&lt;p&gt;Consider a large ATC facility, where a range of ATC services are provided and each position requires a dedicated person to manage (unlike small airports, where the same guy is ground + tower). Which positions are considered the most demanding, and it would make sense to assign a senior and experienced controller there?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would imagine, Clearance Delivery is probably the easiest one, then Enroute, Approach / Departure, Ground and finally Tower. What's the training sequence recommended by the authorities for a new controller? After all, assigning a fresh trainee to LAX tower or JFK ground does not sound like a good idea.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastActivityDate="2016-06-04T19:41:06.503" Title="Which air traffic controller positions are considered most challenging?" Tags="&lt;air-traffic-control&gt;" AnswerCount="0" CommentCount="3" ClosedDate="2016-06-04T23:33:54.707" ContentLicense="CC BY-SA 3.0" />
  <row Id="28017" PostTypeId="1" CreationDate="2016-06-04T21:17:52.370" Score="7" ViewCount="2250" Body="&lt;p&gt;I'm sorry if this is a little fantastical, but I'm just wondering if this type of maneuver is possible in any way. I understand if this question gets pulled. I'm trying to make a little action-animation-cgi and just wondering if this was ever a last-resort option for maybe two planes, maybe one is a bit larger than the other but maybe similar speeds could be maintained for the one plane that is running out of fuel could latch-on somehow. &lt;/p&gt;&#xA;" OwnerUserId="9105" LastActivityDate="2016-12-21T21:13:36.277" Title="Could a plane land inside or on top of another plane in flight?" Tags="&lt;emergency&gt;" AnswerCount="4" CommentCount="11" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="28018" PostTypeId="2" ParentId="28017" CreationDate="2016-06-04T21:48:16.600" Score="9" Body="&lt;p&gt;The airforce used to have Parasite Fighters that could be launched and then recovered by a larger aircraft. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Parasite_aircraft&quot; rel=&quot;noreferrer&quot;&gt;Parasite Fighter&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8bNVY.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8bNVY.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Space Shuttle was routinely transported on the back of two specially equipped B747s.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.m.wikipedia.org/wiki/Shuttle_Carrier_Aircraft#&quot; rel=&quot;noreferrer&quot;&gt;Shuttle Carrier Aircraft&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/wo0uG.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wo0uG.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="12589" LastEditorUserId="12589" LastEditDate="2016-06-05T01:51:07.523" LastActivityDate="2016-06-05T01:51:07.523" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="28019" PostTypeId="1" AcceptedAnswerId="29022" CreationDate="2016-06-05T00:27:00.437" Score="4" ViewCount="2975" Body="&lt;p&gt;The overall aerodynamic force acting on a wing that is creating lift is not straight upward but is inclined backward. We usually consider the vertical and horizontal axes of the force separately. Lift is defined as the portion of the resultant force that is perpendicular to the relative wind, and induced drag is the portion parallel with it. The slope of the angle of the resultant force is the L/D ratio. This ratio changes with angle of attack as shown in the following diagram. As the AoA increases this vector leans further back creating a different L/D ratio (more drag for the same amount of lift).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/I03xP.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/I03xP.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then looking from the wing's point of view, the portion of the RF perpendicular to the chord is the normal force (N) and the part parallel to it is the axial force (A). We can see that the the angle of the RF with respect to the wing chord is less affected by changes in AoA. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/WxG3O.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/WxG3O.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've never seen a chart that graphs out the N/A relationship. Does this ratio change at all with AoA or is it a fixed property of the wing design? If it is not fixed, what dynamic factors (speed, AoA, etc.) affect the direction of the resultant force?      &lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="3201" LastEditDate="2016-06-05T10:55:15.470" LastActivityDate="2016-06-05T18:29:08.747" Title="What factors determine the direction of the resultant force vector?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;drag&gt;" AnswerCount="2" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="29020" PostTypeId="2" ParentId="28019" CreationDate="2016-06-05T09:40:50.530" Score="1" Body="&lt;p&gt;The angle of attack changes the L/D ratio, yes. Image the angle increased to 90 degrees (coming straight from the bottom). I suppose you could call that 100% lift and 0% drag.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Not sure how useful that is... From another point of view, that's 100% drag and 0% lift. &lt;a href=&quot;https://en.wikipedia.org/wiki/Pugachev%27s_Cobra&quot; rel=&quot;nofollow&quot;&gt;Pugachev's Cobra&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="11953" LastActivityDate="2016-06-05T09:40:50.530" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29021" PostTypeId="2" ParentId="9339" CreationDate="2016-06-05T09:42:34.720" Score="-1" Body="&lt;p&gt;B777-31H(ER) can fly further than B777-31H.&lt;/p&gt;&#xA;" OwnerUserId="15274" LastActivityDate="2016-06-05T09:42:34.720" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29022" PostTypeId="2" ParentId="28019" CreationDate="2016-06-05T12:23:34.847" Score="2" Body="&lt;p&gt;Yes, the resulting force is not perpendicular to the wing's chord but can point either way, slightly forward and backward. The very first polar charts which were published show this nicely, because those plots were true polar plots and used the wing chord as the reference orientation for 0°.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/9r6rN.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/9r6rN.png&quot; alt=&quot;Illustration on page 196 of Otto Lilienthal&amp;#39;s &amp;quot;Der Vogelflug als Grundlage der Fliegekunst&amp;quot;&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Illustration on page 196 of Otto Lilienthal's &quot;Der Vogelflug als Grundlage der Fliegekunst&quot; showing measurements on model wings as polar plots (&lt;a href=&quot;http://www.museumnet.lilienthal-museum.de/digitalisate/gl_10.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;). Note the left part: Here the forces are plotted in the wing section's coordinate system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The N/A relationship was covered by the work of Edward C. Polhamus, who did a lot of research on this at NACA Langley and published several papers with equations for &lt;a href=&quot;http://www.pdas.com/refs/tp1500.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;calculating the leading edge thrust&lt;/a&gt;, the force which helps to tilt the resultant force vector forward.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="8730" LastEditDate="2016-06-05T18:29:08.747" LastActivityDate="2016-06-05T18:29:08.747" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="29023" PostTypeId="2" ParentId="22603" CreationDate="2016-06-05T13:02:09.913" Score="0" Body="&lt;p&gt;Nacelles usually have structural components like frames,formers and stringers  due to there sizes, and are found mostly on turbine engines. while Cowlings don't always have structural components and are usually smaller in size compare to Nacelles as seen on piston engine aircraft.&lt;/p&gt;&#xA;" OwnerUserId="15275" LastActivityDate="2016-06-05T13:02:09.913" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29024" PostTypeId="2" ParentId="27996" CreationDate="2016-06-05T13:14:06.503" Score="10" Body="&lt;p&gt;This is a very tricky topic. Basically, you need a clear definition of what is part of the engine-related drag and what is counted towards airframe drag. Splitting up drag between components will always produce an arbitrary result.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An intake can generate thrust as well as drag. In case of the SR-71 at Mach 3, the intake &lt;a href=&quot;https://aviation.stackexchange.com/questions/27003/why-does-the-j58-engine-of-the-sr-71-have-a-diffuser-after-the-inlet-spike/27024#27024&quot;&gt;contributed 54% of overall thrust&lt;/a&gt;, if you just look at the pressure distribution over the intake walls.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally, the job of the intake is to feed air to the engine compressor at just the right speed and as homogeneously as possible. This requires it to suck in air when at rest from all around the aircraft, and to ingest only the core of the stream of air flowing towards it at high speed. What is not ingested needs to flow around the intake lips and the engine fairing, and the drag caused by this process even has its own name, being called &lt;a href=&quot;https://www.grc.nasa.gov/www/k-12/airplane/inleth.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;spill drag&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At high speed the intake needs to slow down the oncoming air and does so already ahead of the intake lip at subsonic speed. At supersonic speed this slowing down is &lt;a href=&quot;https://aviation.stackexchange.com/questions/9066/why-cant-jet-engines-operate-with-supersonic-air-and-how-do-they-slow-it-down/9222?s=6%7C0.1057#9222&quot;&gt;accomplished by shocks&lt;/a&gt;, which adds another source of drag. This can be easily counted as part of the airframe drag, but done right this slowing down will compress the air, which in turn will increase thrust. Apart from viscous losses, this compression pays for itself and is almost drag-neutral in a good design and at ideal conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Next is the flow around the intake. Just throttling the engine will change the airflow through it and thus the flow pattern around the intake. You can imagine that some configurations show marked changes in aerodynamic drag depending on the throttle setting. In case of the Eurofighter, the vicinity of the canard will even cause throttle changes to result in notable pitch moment changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To answer your question: Yes, the intake will produce drag, and how much it does depends on how you define drag. It is certainly wrong to think that the stream tube hitting the intake will just disappear into it and not add any drag.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-06-23T16:35:02.813" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29025" PostTypeId="1" CreationDate="2016-06-05T13:22:44.203" Score="1" ViewCount="397" Body="&lt;p&gt;The scope of my Master Thesis is the development of an assignment algorithm of aircraft types to routes with a given distance. As part of violation checks I'm validating the possible range of the AC type against the route distances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As defined per payload-range diagram the max range of an aircraft type is not a static value but depends on the amount of payload desired. For a more realistic approach I'm looking for values of the max range at maximum payload of every aircraft type defined in ICAO Doc 8643.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However this value is not very easy to find out. Does anyone have an idea where to find a list of all (or at least all major aircraft types) max ranges at max payload of all aircraft types given in ICAO Doc 8643 grouped by the ICAO Designators (e.g. A332, B773, etc.)&lt;/p&gt;&#xA;" OwnerUserId="15276" LastEditorUserId="19" LastEditDate="2016-11-21T09:04:16.283" LastActivityDate="2016-11-21T09:04:16.283" Title="Where can I find a collection of maximum range at maximum payload values for all aircraft types?" Tags="&lt;icao&gt;&lt;datasets&gt;&lt;range&gt;&lt;payload&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29026" PostTypeId="2" ParentId="28017" CreationDate="2016-06-05T14:44:43.033" Score="6" Body="&lt;p&gt;The Navy has already done this using airships.  Here is a video showing launch and recovery. &lt;a href=&quot;https://m.youtube.com/watch?v=IWoEQRl8dCs&quot; rel=&quot;noreferrer&quot;&gt;USS Macon launching a recovering aircraft.&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8210" LastActivityDate="2016-06-05T14:44:43.033" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29027" PostTypeId="2" ParentId="28017" CreationDate="2016-06-05T14:55:53.827" Score="5" Body="&lt;p&gt;Let me take a stab at the &quot;inside another plane part&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the smallest trainer planes is the Cessna 172, with a wingspan of 36'.&lt;br&gt;&#xA;One of the biggest cargo planes is the C-5 Galaxy, with an inside diameter of 19'.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So right there, you'd be hard-pressed to find a small plane that could even fit inside a larger plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The next problem is airspeed:  The C-172 needs to travel at least 40 kts to maintain flight, and this is 40kts &lt;strong&gt;&lt;em&gt;relative to the air it is in&lt;/em&gt;&lt;/strong&gt;, so if it were inside the cargohold of a larger plane, it needs to be traveling 40 kts faster than the larger plane.  I couldn't find a canonical reference for the C5 Galaxy's minimum speed, but I can estimate it around 140 kts.&lt;p&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This means that on approach to the host-plane, the smaller plane would need to be doing about 180 kts relative to the outside air.  That is around the fastest speed the Cessna is capable of; it would need to be in a considerable descent at full power to achieve that speed. The propeller would be turning about 2700 RPM.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the transition from outside the host to inside the host, the small plane needs to slow its propeller from 180kts (2700 RPM) to only 40 kts(1200 RPM).  The propeller needs to slow to landing speed nearly instantaneously, otherwise the fast propeller would accelerate the smaller plane relative to its host.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, the parasite-plane would need to be in a considerable descent at full power to make an approach speed.  Then as it enters the host-plane, it would need to level off and slow its propeller drastically. This seems incredibly risky.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Once you're inside the larger plane, the Cessna has a published landing roll out of about 500 feet.   The C-5 Galaxy has a length of around 250 feet. So you'd need some sort of arrester cable system, like found on aircraft carriers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, in summary:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Most big planes are not big enough to fit small planes inside&lt;/li&gt;&#xA;&lt;li&gt;Small planes cannot go fast enough to catch up to a big plane's minimum speed.&lt;/li&gt;&#xA;&lt;li&gt;The airspeed transition from outside a big plane to inside a big plane is extreme and sudden.&lt;/li&gt;&#xA;&lt;li&gt;There isn't a lot of space in a big plane for a landing roll out.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;So, I would generally say &quot;No&quot;, landing inside a larger plane seems impossible.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hEDN9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hEDN9.jpg&quot; alt=&quot;Busted!&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="43" LastEditorUserId="43" LastEditDate="2016-06-08T12:11:06.360" LastActivityDate="2016-06-08T12:11:06.360" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29028" PostTypeId="2" ParentId="28014" CreationDate="2016-06-05T16:51:20.570" Score="5" Body="&lt;p&gt;I can tell you that in economy, the 777 noise was, in my opinion, almost unbearable. The A380 was almost silent. I have been on both on long haul to the uk, and their is a world of difference in the noise levels. Will never fly 777 again.&lt;/p&gt;&#xA;" OwnerUserId="15252" LastActivityDate="2016-06-05T16:51:20.570" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29030" PostTypeId="1" CreationDate="2016-06-05T17:14:21.417" Score="-1" ViewCount="2109" Body="&lt;p&gt;If a body has a greater than one thrust to weight ratio, then is the centrifugal force acting perpendicular to the Earth's gravitational pull that allows it to fly ?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or are there other forces that I am not aware of being at play here ?&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Further Clarification&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, when a body is moving on the surface of the Earth, we can assume that it adheres to some semblance of circular motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any body in circular motion will experience an outward force perpendicular to the direction of motion.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6HDRW.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6HDRW.png&quot; alt=&quot;Sample&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, given enough thrust, can any body fly because of the centrifugal force created against Earth's gravitational force ?&lt;/p&gt;&#xA;" OwnerUserId="14881" LastEditorUserId="14881" LastEditDate="2016-06-05T20:14:43.623" LastActivityDate="2016-06-06T07:59:09.517" Title="Is it centrifugal force that allows a non-aerodynamic body to achieve lift purely because of thrust?" Tags="&lt;aerodynamics&gt;&lt;lift&gt;&lt;aircraft-physics&gt;&lt;g-forces&gt;&lt;groundspeed&gt;" AnswerCount="2" CommentCount="11" ClosedDate="2016-06-06T00:53:48.253" ContentLicense="CC BY-SA 3.0" />
  <row Id="29031" PostTypeId="2" ParentId="29030" CreationDate="2016-06-05T20:13:28.060" Score="0" Body="&lt;p&gt;It is not centrifugal force that allows a &lt;s&gt;non-aerodynamic&lt;/s&gt; body not designed to be aerodynamic to achieve lift by harnessing the energy from thrust unless it is going so fast that it is in orbit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If an object is moving fast enough, it would eventually get to the point where it would be in a low orbit; in that case I suppose you could say it is the centrifugal force keeping it at that height (orbiting), and of course, the lower it is the faster it must move, and the more thrust is required to counter the air resistance. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Typically when we talk about something moving through the air, the thing providing a constant height would be the aerodynamic force acting on it.  Even a brick can fly aerodynamically by creating lift from striking air molecules if it has enough thrust to keep its speed high enough to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It is still due to the air's Newtonian action-reaction on the object. Unless of course, we are talking about vertical flight, in which case the lift comes from the Newtonian action-reaction from the thrust, not the air.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I don't mean to exclude thrust vectors here.  Of course, the angle of thrust will play a part even when there is Newtonian aerodynamic lift.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're talking about orbital properties, &lt;a href=&quot;https://space.stackexchange.com/questions/12939/how-can-there-be-different-heights-of-orbit/12949#12949&quot;&gt;check this out&lt;/a&gt; in the space section of SE.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;So, given enough thrust, can any body fly because of the centrifugal&#xA;  force created against Earth's gravitational force?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Yes, but it would be called orbiting, not flying.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="-1" LastEditDate="2017-04-13T12:58:55.350" LastActivityDate="2016-06-05T20:27:42.740" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29032" PostTypeId="1" CreationDate="2016-06-05T20:43:26.713" Score="6" ViewCount="433" Body="&lt;p&gt;I wonder if anyone can help with a hypothetical question. Its for a novel I am researching&#xA;All passengers with a ticket for a flight will pass through normal passport controls but I am told that Pilots can jump a flight if theres a spare seat. I know it might be outside of procedure but...&#xA;Is it feasible that he might join his buddies and get on the plane with them and avoid the official record of him entering and leaving another country say between the USA and Canada?&lt;/p&gt;&#xA;" OwnerUserId="15281" LastEditorUserId="19" LastEditDate="2016-07-04T15:23:58.870" LastActivityDate="2016-07-04T15:23:58.870" Title="Do pilots have the ability to bypass customs when utilizing jump-seat privileges?" Tags="&lt;security&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="29033" PostTypeId="2" ParentId="29030" CreationDate="2016-06-05T21:16:19.960" Score="8" Body="&lt;p&gt;Basically, you're asking 'Can you achieve orbital velocity in atmospheric conditions?'. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Orbital velocity is approximately equal to&lt;/p&gt;&#xA;&#xA;&lt;p&gt;$$v_o \approx \sqrt{\dfrac{GM}{r}}$$&lt;/p&gt;&#xA;&#xA;&lt;p&gt;which, if we &lt;a href=&quot;http://www.wolframalpha.com/input/?i=sqrt((graviational+constant)*(mass+earth)%2F(radius+earth))&quot; rel=&quot;noreferrer&quot;&gt;fill it in at Wolfram.alpha&lt;/a&gt;, yields a velocity of almost 8km/s (yes, per second), or almost 18000mph, or a Mach number of 23.23. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The current speed record for sustained atmospheric flight is just shy of 2200mph (which, interestingly, stems from &lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_airspeed_record&quot; rel=&quot;noreferrer&quot;&gt;1976 and was set by the SR-71 Blackbird&lt;/a&gt;). This means we're still a factor 8 short. Since drag is roughly proportional to the square of your velocity, this means we're a factor 64 short of thrust on a similarly designed airplane. But I think by that time you'll be running into all sorts of interesting exotic effects, not the least of which is that your airplane will desintegrate by the massive amount of compressive heating (basically, you're doing a 'sustained' orbital re-entry maneuver in a &lt;strong&gt;much&lt;/strong&gt; thicker part of the atmosphere).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer is then, &lt;strong&gt;hell no&lt;/strong&gt;. Not as long as Earth has an atmosphere.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Note: if you're asking about vacuum conditions, then the figure you're looking for is delta-V, not thrust-to-weight ratio. The delta-v of your craft must exceed aforementioned orbital velocity. Your T/W ratio doesn't come in to play at all. &lt;/p&gt;&#xA;" OwnerUserId="4108" LastEditorUserId="4108" LastEditDate="2016-06-06T07:59:09.517" LastActivityDate="2016-06-06T07:59:09.517" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29034" PostTypeId="2" ParentId="8851" CreationDate="2016-06-05T21:39:56.603" Score="-1" Body="&lt;p&gt;There is a BIG difference.  The curve of the blades is reversed.  On a propellor, the leading edge is close to the propellor disk, with the flatter surface towards the rear.  In a turbine, the leading edge points forward (into the wind), with the flatter surface also forward. &lt;/p&gt;&#xA;" OwnerUserId="15283" LastActivityDate="2016-06-05T21:39:56.603" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29035" PostTypeId="2" ParentId="29032" CreationDate="2016-06-05T23:22:57.850" Score="5" Body="&lt;p&gt;Just to put down as an answer what has been pretty well covered in the comments...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All pilots, jump-seating or not, will still clear customs.  They may have a separate line, but there will still be the normal record of their entry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond that, the airline absolutely knows who they let on the jumpseat for each flight -- so &quot;no record&quot; won't really happen in any event.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-06-05T23:22:57.850" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29036" PostTypeId="1" CreationDate="2016-06-06T02:10:01.440" Score="6" ViewCount="570" Body="&lt;p&gt;On a recent flight, I was able to observe visual artefacts over the wing (Boeing 767-300 in cruise). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can see them in the image below; they look like creases in a surface. They moved forwards and backwards over the wing. Later in the flight they extended to the end of the wing; at this point, they extended no further than a few metres.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've added red and yellow arrows pointing to their ends - as you can see, one of them appears to fork.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/XWJjg.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/XWJjg.jpg&quot; alt=&quot;Visual artefacts caused by shockwave over wing&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Adjusting brightness and contrast makes the artefacts more visible:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/dU0Ze.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/dU0Ze.jpg&quot; alt=&quot;Same image with increased contrast&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I understand that this artefact is caused by a shockwave produced by supersonic airflow over the forward part of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'd be interested to know: &lt;em&gt;what exactly is it that I am seeing?&lt;/em&gt; &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Is the artefact projected onto the surface of the wing, like a&#xA;shadow?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Is the artefact a refractive distortion caused by different air&#xA;densities? &lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;In this image, there appear to be two creases, one behind the other -&#xA;what do they represent?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What does the fork at the right-hand end of one of the 'creases'&#xA;represent?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;What do the darker and lighter portions of the 'creases' represent?&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="4170" LastEditDate="2016-06-06T06:06:21.643" LastActivityDate="2017-04-01T08:00:20.660" Title="What do the components of a shockwave's visual artefacts represent?" Tags="&lt;aerodynamics&gt;&lt;shock-waves&gt;" AnswerCount="1" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29037" PostTypeId="1" CreationDate="2016-06-06T04:25:48.707" Score="8" ViewCount="17452" Body="&lt;p&gt;I would like to know the difference between Distant (D) NOTAMs, Local (L) NOTAMs and FDC NOTAMs in the US. Is their meaning obsolete or still in use by the FAA?&lt;/p&gt;&#xA;" OwnerUserId="14891" LastEditorUserId="62" LastEditDate="2016-06-06T19:31:41.360" LastActivityDate="2016-06-07T15:00:28.060" Title="What is the difference between Distant (D) NOTAMs, Local (L) NOTAMs and FDC NOTAMs in the US?" Tags="&lt;usa&gt;&lt;notam&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29038" PostTypeId="2" ParentId="29037" CreationDate="2016-06-06T05:14:48.957" Score="3" Body="&lt;p&gt;A really great source for these kinds of answers is the Pilot's Handbook of Aeronautical Knowledge, or PHAK.  You can dowload it for free from the FAA &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;The answer to your question from chapter 13, pages 13-3 &amp;amp; 13-4 of the PHAK:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;NOTAMs provide the most current information available.  They provide&#xA;time-critical information on airports and  changes that affect the&#xA;national airspace system (NAS) and are of concern to IFR operations.&#xA;NOTAM information is classified into three categories. These are&#xA;NOTAM-D or  distant, NOTAM-L or local, and flight data center (FDC)&#xA;NOTAMs. NOTAM-Ds are attached to hourly weather reports and are&#xA;available at automated flight service stations (AFSS) or FSS.&lt;/p&gt;&#xA;&lt;p&gt;FDC NOTAMs are issued by the National Flight Data Center and contain&#xA;regulatory information, such as temporary flight restrictions or an&#xA;amendment to instrument approach procedures. The NOTAM-Ds and FDC&#xA;NOTAMs are contained in the NOTAM publication, which is issued every&#xA;28 days. Prior to any flight, pilots should check for any NOTAMs that&#xA;could affect their intended flight.&lt;/p&gt;&#xA;&lt;p&gt;NOTAM-D information includes such&#xA;data as taxiway closures, personnel and equipment near or crossing&#xA;runways,  and airport lighting aids that do not affect instrument&#xA;approach criteria, such as visual approach slope indicator (VASI).&#xA;NOTAM-D information is distributed locally only and is not attached to&#xA;the hourly weather reports. A separate file of local NOTAMs is&#xA;maintained at each FSS for facilities  in their area only. NOTAM-D&#xA;information for other FSS areas must be specifically requested&#xA;directly from the FSS that has responsibility for the airport&#xA;concerned.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;NOTAMs are far from obsolete.  They are critical and pilots are actually required to familiarize themselves with all applicable information before each flight.  NOTAMs are arguably the most important vehicles to help pilots satisfy that requirement.&lt;/p&gt;&#xA;&lt;p&gt;The civilian NOTAM-L has been discontinued snd evetything that one qualified as a -L is now -D.&lt;/p&gt;&#xA;" OwnerUserId="11201" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-06-07T15:00:28.060" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29040" PostTypeId="1" AcceptedAnswerId="29044" CreationDate="2016-06-06T10:01:39.510" Score="32" ViewCount="8751" Body="&lt;p&gt;A &lt;a href=&quot;https://en.wikipedia.org/wiki/Wing_fence&quot; rel=&quot;noreferrer&quot;&gt;Wing Fence&lt;/a&gt; is a straight, vertical &quot;fence&quot; running from forwards to backwards down the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/iV2KP.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-17&quot; rel=&quot;noreferrer&quot;&gt;MiG-17&lt;/a&gt; has three fences per wing. I've also seen them on delta-winged aircraft such as the &lt;a href=&quot;https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25&quot; rel=&quot;noreferrer&quot;&gt;MiG-25&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The purpose of the wing fence is to prevent the air from flowing sideways over the wing. Air instead becomes trapped between the fences and flows front to back as normal. This is the ideal condition for creating lift, because the air follows the camber of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So why doesn't the &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;noreferrer&quot;&gt;Concorde&lt;/a&gt; have them?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;img src=&quot;https://i.stack.imgur.com/qdLBE.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The even more extreme sweep (at first) of Concorde's wing seems to me like it would induce even more sideways-flowing air, meaning it should benefit even more from wing fences.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I noticed the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tupolev_Tu-144&quot; rel=&quot;noreferrer&quot;&gt;Tupolev Tu-144&lt;/a&gt; doesn't have them either.)&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="2956" LastEditDate="2016-06-07T06:01:30.490" LastActivityDate="2016-06-08T06:50:21.523" Title="Why doesn't the Concorde have any wing fences?" Tags="&lt;aircraft-design&gt;&lt;wing&gt;&lt;concorde&gt;" AnswerCount="2" CommentCount="8" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29041" PostTypeId="1" AcceptedAnswerId="29050" CreationDate="2016-06-06T11:06:30.917" Score="8" ViewCount="3797" Body="&lt;p&gt;What's the point of the usual &quot;please keep your seat belt fastened until the aircraft stops completely (at the gate)&quot; in large passenger aircrafts? Since the plane is on the ground, it is not moving very quick. Even if it stopped abruptly, the seat belt won't prevent me from banging my head against the seat in front of me since it's a two-point seat belt.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The only reason I can think of is if two aircraft collided with each other, which could potentially generate enough force for the seat belt to be useful. Though, I could argue that when a plane is taxiing to the gate, it has to abide to a certain speed limit, which would render any kind of collision not serious enough to be prevented by two-point seat belts.&lt;/p&gt;&#xA;" OwnerUserId="9112" LastActivityDate="2016-06-07T20:49:43.557" Title="Why do you have to keep your seat belt fastened after landing?" Tags="&lt;safety&gt;&lt;taxiing&gt;" AnswerCount="3" CommentCount="9" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29042" PostTypeId="2" ParentId="29040" CreationDate="2016-06-06T12:27:01.863" Score="27" Body="&lt;p&gt;The Concorde makes use of vortex lift (&lt;a href=&quot;http://www.heritageconcorde.com/#!the-wing/c21eq&quot; rel=&quot;noreferrer&quot;&gt;link&lt;/a&gt;).&lt;br&gt;&#xA;While one of the reasons for applying wing fences is to prevent air from flowing sideways, they are also able to create vortices (&lt;em&gt;R. Whitford, Design for Air Combat, 1987&lt;/em&gt;), though this only applies to wing fences that don't extend over the entire wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The need for vortex generators can be overcome if the wing itself is designed in such a way that a vortex is generated. Besides that, the vortex itself is very stable and also prevents air from flowing sideways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/mhZV4.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/mhZV4.jpg&quot; alt=&quot;Concorde vortex flow&quot;&gt;&lt;/a&gt;&#xA;(&lt;a href=&quot;http://www.pprune.org/tech-log/353898-strongest-wing-tip-vortices-when-slow-clean-heavy-but-why-2.html#post5292022&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;)&lt;/p&gt;&#xA;" OwnerUserId="598" LastEditorUserId="598" LastEditDate="2016-06-08T06:50:21.523" LastActivityDate="2016-06-08T06:50:21.523" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29043" PostTypeId="2" ParentId="29032" CreationDate="2016-06-06T12:58:07.190" Score="5" Body="&lt;p&gt;I have flown numerous times on jump seats. I just enter the airport as anyone else, report to the check-in desk and wait there until check-in closes. With the check-in closed the phone the gate and ask for the number of seats available. With all the seats taken they ask the captain if they would allow the jump seats to be taken. Check-in and Security is done as with a regular ticket. I also do not fly as airline staff and have to que in the normal lines and can't take the crew shortcut.&#xA;On my boarding class the booking/travel class is different.&lt;/p&gt;&#xA;" OwnerUserId="15202" LastActivityDate="2016-06-06T12:58:07.190" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29044" PostTypeId="2" ParentId="29040" CreationDate="2016-06-06T13:35:32.373" Score="44" Body="&lt;p&gt;The main &lt;a href=&quot;https://aviation.stackexchange.com/questions/25198/what-is-the-difference-between-a-stall-fence-and-a-vortex-generator&quot;&gt;purpose of the wing fence&lt;/a&gt; is to prevent the boundary layer thickening in the wing due to the spanwise flow observed in swept wing, as can be seen below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pRvBa.gif&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pRvBa.gif&quot; alt=&quot;Spanwise flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;http://fuckyeahfluiddynamics.tumblr.com/post/16984040595/flow-over-a-swept-wing-behaves-very-differently&quot; rel=&quot;noreferrer&quot;&gt;fuckyeahfluiddynamics.tumblr.com&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the reason for having wing fence in aircraft such as Mig-25- to avert stall and improve stability. In case of highly swept wing like the Concorde, this is not required as the mode of generation of lift is different- using &lt;a href=&quot;https://aviation.stackexchange.com/questions/21069/what-is-vortex-lift&quot;&gt;vortex lift&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/j1i0o.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/j1i0o.jpg&quot; alt=&quot;Concorde wing&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Vortices over the Concorde wing, Separation in three-dimensional steady flow, ONERA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, there is a significant cross flow, as can be seen in the following image:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/AFljJ.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/AFljJ.jpg&quot; alt=&quot;Cross sectional Flow&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Flow above the Concorde Wing, Separation in three-dimensional steady flow, ONERA&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Due to this, the wing fences are not required in case of highly swept wings like Delta and Ogival wings (as in Concorde), where separation leads to vortex lift. Mig- 25 wings, though highly swept, was neither of these- the wing generated lift by conventional manner.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-06-06T13:35:32.373" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="29045" PostTypeId="1" CreationDate="2016-06-06T14:11:12.473" Score="9" ViewCount="1406" Body="&lt;p&gt;I know turbofans are less efficient than propellers due to accelerating a smaller mass of air faster. So my question here is not comparing turbofans vs other engines, but compare how inefficient is a turbofan operating at take off and low speeds compared to that same turbofan in its optimal conditions?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, how much is the efficiency loss? Are we talking about 5% or about 50%?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, why exactly that loss of efficiency happen (again, compared to the same engine at optimal cruise conditions)? Is it just the speed differential between the exhaust and aircraft airspeed, or is it something to do with the compressor/turbine efficiency?&lt;/p&gt;&#xA;" OwnerUserId="14683" LastEditorUserId="19" LastEditDate="2016-06-22T13:18:24.553" LastActivityDate="2017-05-30T23:10:59.633" Title="How does the efficiency of a turbofan compare between take off speeds and optimal conditions?" Tags="&lt;turbofan&gt;&lt;efficiency&gt;" AnswerCount="1" CommentCount="2" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29047" PostTypeId="1" AcceptedAnswerId="29048" CreationDate="2016-06-06T14:26:26.580" Score="10" ViewCount="632" Body="&lt;p&gt;On a recent trip to the &lt;a href=&quot;https://en.wikipedia.org/wiki/Sinsheim_Auto_%26_Technik_Museum&quot; rel=&quot;nofollow noreferrer&quot;&gt;Technikmuseum Sinsheim&lt;/a&gt;, I noticed that the back of the Tupolev TU-144 is not symmetric. &#xA;Please take a look at the picture I took to understand what I mean:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/wrRXu.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/wrRXu.jpg&quot; alt=&quot;&quot;&gt;&lt;/a&gt;&#xA;(Please don't mind the crane, the Tupolev was getting cleaned that day)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those parts most likely serve some aerodynamic/stabilizing purpose, but what exactly do they do? Why aren't they the same on both sides?&lt;/p&gt;&#xA;" OwnerUserId="14457" LastEditorUserId="22726" LastEditDate="2019-01-24T03:46:11.947" LastActivityDate="2019-01-24T03:46:11.947" Title="What are these unsymmetrical parts at the tail of the Tupolev TU-144?" Tags="&lt;aerodynamics&gt;&lt;supersonic&gt;&lt;tail&gt;&lt;tu-144&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29048" PostTypeId="2" ParentId="29047" CreationDate="2016-06-06T14:38:51.330" Score="12" Body="&lt;p&gt;The four parts you're referring to contain the actuation mechanism for the rudder, similar to the wing pods that contain the flap actuation mechanism.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason they are not arranged symmetrically is that the rudder has two sections (you can see the 'cut' in the middle in your image)- apparently to provide redundancy and improve safety. So,each section has two actuation mechanisms on the same side, with both of them in opposite sides.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Concorde had a similar arrangement, albeit with only a single mechanism on either side, as can be seen below.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/8po7O.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/8po7O.jpg&quot; alt=&quot;Concorde rear&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;By Simon Boddy, CC BY-SA 2.0, &lt;a href=&quot;https://commons.wikimedia.org/w/index.php?curid=31619795&quot; rel=&quot;noreferrer&quot;&gt;https://commons.wikimedia.org/w/index.php?curid=31619795&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-06-06T14:38:51.330" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29050" PostTypeId="2" ParentId="29041" CreationDate="2016-06-06T15:59:09.993" Score="12" Body="&lt;p&gt;Ground operations are just as dangerous as air operations. Strictly speaking the &lt;a href=&quot;https://en.wikipedia.org/wiki/Tenerife_airport_disaster&quot; rel=&quot;nofollow noreferrer&quot;&gt;deadliest aviation incident actually happened on the ground&lt;/a&gt; (not saying seatbelt played a role or not however severe accidents do happen on the ground). The comments cover things well, (&lt;a href=&quot;https://aviation.stackexchange.com/questions/29041/why-do-you-have-to-keep-your-seat-belt-fastened-after-landing#comment70652_29041&quot;&gt;keeping people seated&lt;/a&gt;, &lt;a href=&quot;https://aviation.stackexchange.com/questions/29041/why-do-you-have-to-keep-your-seat-belt-fastened-after-landing/29050?noredirect=1#comment70703_29050&quot;&gt;keeping people from accessing over head compartments&lt;/a&gt; etc.) Planes are not safe simply because they are on the ground, they are only safe from &lt;em&gt;flight related incidents&lt;/em&gt; and once on the ground they are susceptible to ground related incidents. &lt;a href=&quot;http://flightsafety.org/archives-and-resources/ground-accident-prevention-gap&quot; rel=&quot;nofollow noreferrer&quot;&gt;By some estimates 27,000 ground incidents&lt;/a&gt; happen a year. The fact remains there are plenty of things to hit on the ground and plenty that can go wrong in taxi. These accidents are &lt;a href=&quot;http://www.icao.int/APAC/Meetings/2012_APRAST/OccurrenceCategoryDefinitions.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;classified by ICAO under&lt;/a&gt; (RAMP) and (GCOL) codes (and potentially others). &lt;a href=&quot;http://www.boeing.com/resources/boeingdotcom/company/about_bca/pdf/statsum.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Boeing has a breakdown of accidents by flight category&lt;/a&gt; (taxi and ground ops make up about 10%).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://rgl.faa.gov/REGULATORY_AND_GUIDANCE_LIBRARY/RGFAR.NSF/0/00802fa7c076996f862571ab0050301d!OpenDocument&quot; rel=&quot;nofollow noreferrer&quot;&gt;Furthermore here in the US under the FAA FAR 91.107&lt;/a&gt; as well as &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/121.311&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAR 121.311 in the commercial case(basically the same wording)&lt;/a&gt; requires it&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;...(3) Except as provided in this paragraph, each person on board a&#xA;  U.S.-registered civil aircraft (except a free balloon that&#xA;  incorporates a basket or gondola or an airship type certificated&#xA;  before November 2, 1987) must occupy an approved seat or berth with a&#xA;  safety belt and, if installed, shoulder harness, &lt;strong&gt;properly secured&#xA;  about him or her during movement on the surface&lt;/strong&gt;, takeoff, and landing.&#xA;  For seaplane and float equipped rotorcraft operations during movement&#xA;  on the surface, the person pushing off the seaplane or rotorcraft from&#xA;  the dock and the person mooring the seaplane or rotorcraft at the dock&#xA;  are excepted from the preceding seating and safety belt requirements....&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2016-06-06T18:51:42.153" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29052" PostTypeId="2" ParentId="29037" CreationDate="2016-06-06T19:30:55.120" Score="5" Body="&lt;p&gt;Short answer: D NOTAMs are about airports and navigation facilities; FDC NOTAMs are about airspace, procedures or regulations; and L NOTAMs don't exist any more (unless you're in the military).&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;The information on NOTAM types is a bit messy and inconsistent, to say the least. The Alaskan FSS &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/alaska/fai/notam/ntm_overview/&quot; rel=&quot;nofollow noreferrer&quot;&gt;lists 11 types&lt;/a&gt;; the PHAK &lt;a href=&quot;http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/&quot; rel=&quot;nofollow noreferrer&quot;&gt;13-3 lists 3 types&lt;/a&gt; (as acpilot mentioned in &lt;a href=&quot;https://aviation.stackexchange.com/a/29038/62&quot;&gt;his answer&lt;/a&gt;); the &lt;a href=&quot;http://www.faa.gov/air_traffic/publications/media/aim.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIM 5-1-3 lists five&lt;/a&gt; in its NOTAM section, plus GPS NOTAMs in the GPS section.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And the FAA's &lt;a href=&quot;https://www.notams.faa.gov/dinsQueryWeb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;military NOTAM site&lt;/a&gt; lists yet more types in &lt;a href=&quot;https://www.notams.faa.gov/faq.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;their FAQ&lt;/a&gt;  such as M, V, W and F.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Anyway, here's what the AIM says about D and FDC NOTAMs:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;NOTAM (D)&lt;/strong&gt; information is disseminated for all navigational facilities&#xA;  that are part of the National Airspace System (NAS), all public use&#xA;  airports, seaplane bases, and heliports listed in the Chart Supplement&#xA;  U.S. [...]  NOTAM (D) information includes such data as taxiway&#xA;  closures, personnel and equipment near or crossing runways, and&#xA;  airport lighting aids that do not affect instrument approach criteria,&#xA;  such as VASI.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;FDC NOTAMs.&lt;/strong&gt; On those occasions when it becomes necessary to&#xA;  disseminate information which is regulatory in nature, the National&#xA;  Flight Data Center (NFDC), in Washington, DC, will issue an FDC NOTAM.&#xA;  FDC NOTAMs contain such things as amendments to published IAPs and&#xA;  other current aeronautical charts. They are also used to advertise&#xA;  temporary flight restrictions caused by such things as natural&#xA;  disasters or large-scale public events that may generate a congestion&#xA;  of air traffic over a site.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;According to the Alaska FSS page, NOTAM(L) doesn't exist any more for civilian use:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;NOTAM (L):&lt;/strong&gt;  A NOTAM given local dissemination by voice and other&#xA;  means, such as telautograph and telephone, to satisfy local user&#xA;  requirements.  This type of NOTAM is now used only in the military&#xA;  NOTAM system.  All NOTAMs previously considered NOTAM (L)s in the&#xA;  civil NOTAM system are now considered NOTAM (D)s.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That's confirmed by &lt;a href=&quot;https://www.notams.faa.gov/baseops/afi11-208(i).pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;AIR FORCE INSTRUCTION 11-208 (I)&lt;/a&gt;, which describes NOTAM(L) as a military type:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;4.2.1. Military.&lt;/strong&gt;&lt;br&gt;&#xA;  [...]&lt;br&gt;&#xA;  &lt;strong&gt;4.2.1.2. Local NOTAM (L series).&lt;/strong&gt; Local NOTAMs are non-critical and non-safety related information that is essential for the flying and&#xA;  support communities to know. Facility managers may establish the&#xA;  parameters for local NOTAM determination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Civilian L NOTAMs are now D NOTAMs that start with the specific facility code. You can find them on the &lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;civilian NOTAM site&lt;/a&gt;, e.g.:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;!LOU 05/077 LOU RWY 15/33 CLSD&#xA;  1605091213-1606222000&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;And to address your final point, NOTAMs are not obsolete. There needs to be some way to inform pilots about temporary changes or things that happen at short notice, and that's what NOTAMs are for. Many people feel that the system could be improved somehow - pulling up the NOTAMs for even a short flight can give you dozens of results - but there's no doubt that it's needed. Reviewing NOTAMs is an important preflight step, and examiners often test you on it during checkrides. There are plenty of NTSB accident reports that mention NOTAMs, usually &lt;a href=&quot;http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20120405X40552&amp;amp;key=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;in cases where the pilot didn't review them&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.497" LastActivityDate="2016-06-07T12:42:47.537" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29053" PostTypeId="1" CreationDate="2016-06-06T19:46:39.323" Score="7" ViewCount="1555" Body="&lt;p&gt;So my student pilot license is missing a middle name, but my drivers license, written exam, and passport all have it printed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've spoken with the DPE, and he says it may be an issue, or it may not, and that he is going to look into it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've called FSDO, airmen certification branch, and other DMVesque organizations, and they all seem to say the same thing: &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Oh, you need to talk to (insert amorphous bureaucracy here)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Does anyone know who I actually need to talk to, or if this is even an issue? Do I just need to call FSDO and insist that they fix the issue, or what?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The DPE said that with the written exam being OK it may be a non-issue. Would love to hear from a DPE on here if possible.&lt;/p&gt;&#xA;" OwnerUserId="267" LastEditorUserId="19" LastEditDate="2016-06-21T16:05:51.260" LastActivityDate="2016-06-21T16:05:51.260" Title="Is it necessary to have my full name (including middle name) on my student pilot license?" Tags="&lt;faa&gt;&lt;pilot-certification&gt;&lt;checkride&gt;&lt;fsdo&gt;" AnswerCount="1" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29054" PostTypeId="1" CreationDate="2016-06-06T20:04:53.003" Score="3" ViewCount="77" Body="&lt;p&gt;In the UK, which ATS unit would be responsible for CTR entry clearances? Would the approach controller issue them, or would the approach controller need to co-ordinate a clearance from the aerodrome controller? If the former, I assume the approach controller would pre-note the aerodrome controller?  &lt;/p&gt;&#xA;" OwnerUserId="14520" LastEditorUserId="62" LastEditDate="2016-06-06T20:39:36.677" LastActivityDate="2016-06-07T13:41:27.720" Title="In the UK, which ATS unit would be responsible for CTR entry clearances?" Tags="&lt;air-traffic-control&gt;&lt;approach&gt;&lt;uk&gt;&lt;airport&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29055" PostTypeId="1" CreationDate="2016-06-06T21:34:31.587" Score="4" ViewCount="802" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HAMBEm.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HAMBEm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;By Stefan Krause, Germany (Own work) [&lt;a href=&quot;http://artlibre.org/licence/lal/en&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAL&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File%3AGehling_PLZ106AR_Kruk_OTT_2013_D7N9017_009.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What is the exact dialogue a &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerial_application&quot; rel=&quot;nofollow noreferrer&quot;&gt;crop duster&lt;/a&gt; pilot will have, if any, with ATC on a routine flight?&lt;/p&gt;&#xA;" OwnerUserId="15289" LastEditorUserId="14897" LastEditDate="2017-05-02T11:18:15.020" LastActivityDate="2021-02-12T23:40:18.760" Title="What dialogue would a crop duster typically have with ATC?" Tags="&lt;air-traffic-control&gt;&lt;radio-communications&gt;&lt;visual-flight-rules&gt;&lt;aerial-application&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29058" PostTypeId="2" ParentId="29025" CreationDate="2016-06-06T21:58:49.863" Score="2" Body="&lt;p&gt;Perhaps the DVB Bank report &quot;&lt;a href=&quot;https://www.dvbbank.com/~/media/files/d/dvb-bank-corp/documents/dvb-aviation-finance-commerical-aircraft-booklet-2013.pdf&quot; rel=&quot;nofollow&quot;&gt;An Overview of Commercial Jet Aircraft 2013 - 2014&lt;/a&gt;,&quot; contains the information you are looking for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It contains a type description, performance data, world fleet data and engines for many aircraft types, as well as payload-range diagrams for each aircraft category.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-09-13T20:04:59.130" LastActivityDate="2016-09-13T20:04:59.130" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29060" PostTypeId="2" ParentId="27701" CreationDate="2016-06-06T23:39:45.873" Score="10" Body="&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Molding of the intricate shape requires expensive carbon fiber&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;For it to dampen the noise it's best with 5+ blades (see 3.)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Which is hard to balance and too much weight for your run-of-the-mill 4-seater single engine plane&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;By the time the benefits (see @PeterKämpf 's &lt;a href=&quot;https://aviation.stackexchange.com/a/29092/14897&quot;&gt;answer&lt;/a&gt;) were realized, enter the jet engine for the big planes that would have benefited from it. You only see it in few turboprops nowadays.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&lt;p&gt;The correlation between no. of blades and noise was mainly discovered from tests. Focusing on the cropped table below (see ref. for full table), the noise reduction potential is low for swept tips, and increasing the number of blades gets the full suite of penalties. Reduce the RPM by way of a gearbox for the fullest potential, and the same penalties apply again.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Yfjxl.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Yfjxl.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Metzger, F. Bruce. &amp;quot;An assessment of propeller aircraft noise reduction technology.&amp;quot; Order 50 (1995): 50418D. &lt;a href=&quot;https://ntrs.nasa.gov/citations/19960008053&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://ntrs.nasa.gov/citations/19960008053&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2021-03-20T00:18:04.130" LastActivityDate="2021-03-20T00:18:04.130" CommentCount="2" ContentLicense="CC BY-SA 4.0" />
  <row Id="29061" PostTypeId="1" AcceptedAnswerId="29063" CreationDate="2016-06-06T23:41:18.513" Score="11" ViewCount="1299" Body="&lt;p&gt;I recently saw something I've not previously encountered: shortly after take-off, for a few seconds, an extremely dense tube of condensation rose from about 75cm in front of the wing, in-board of the engine, to a height of about 50cm above the wing and then raced back over it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The tube of condensation was exceptionally well-defined. It appeared to have a diameter of around 15-20cm, which hardly varied, and a very circular cross-section. Its surface was smooth, and it appeared and a few seconds later disappeared as abruptly as if controlled by a switch.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an illustration of some of the airflow over that portion of the wing, it was quite remarkable - I expected it to be more turbulent than that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What was the likely source of this well-defined condensation? It appeared to originate from below and in front of the wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've seen condensation form and travel across portions of the wing many times before, but never in this fashion, so I was thrilled to see it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft was a 767-300 if that makes any difference. &lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="3248" LastEditDate="2016-06-07T10:01:32.883" LastActivityDate="2016-06-07T10:01:32.883" Title="What could cause a distinct tube of condensation over a wing?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29063" PostTypeId="2" ParentId="29061" CreationDate="2016-06-07T00:16:13.417" Score="22" Body="&lt;p&gt;What you might have seen is the condensation due to the vortex generated by the &lt;a href=&quot;https://aviation.stackexchange.com/questions/6399/what-is-this-flange-on-the-engine&quot;&gt;engine nacelle chine&lt;/a&gt;. The image below shows a vortex being generated by the chine.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/tc2mk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/tc2mk.jpg&quot; alt=&quot;Nacelle chine&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image from &lt;a href=&quot;https://www.flickr.com/photos/spiderman/2303021515&quot; rel=&quot;nofollow noreferrer&quot;&gt;flickr.com&lt;/a&gt;. Photo credit- &lt;a href=&quot;https://www.flickr.com/photos/spiderman/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Frank Starmer&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-06-07T01:09:04.810" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29067" PostTypeId="1" CreationDate="2016-06-07T04:50:06.217" Score="7" ViewCount="844" Body="&lt;p&gt;I've always wondered how a private pilot makes sure they have read all the NOTAM's that might affect their flight. There must be thousands of NOTAM's out there. &lt;a href=&quot;https://aviation.stackexchange.com/q/29037/8730&quot;&gt;This question&lt;/a&gt; talks about the many types. Some will be just for the day, some applicable for months. Some affect large areas, some just one taxiway. If doing a cross-country flight, especially to an unfamiliar airport, how does one know how to wade through all of them and be sure they've covered all of those that might affect their flight?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.323" LastActivityDate="2017-03-21T12:09:09.103" Title="How does a pilot make sure they have received all applicable NOTAM's?" Tags="&lt;flight-planning&gt;&lt;notam&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29068" PostTypeId="1" AcceptedAnswerId="29069" CreationDate="2016-06-07T05:12:09.040" Score="24" ViewCount="106609" Body="&lt;p&gt;I saw this quite thick white smoke like thing in the cabin in my last flight, before takeoff that is, while it was taxiing and loading passengers:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ziKLl.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ziKLl.png&quot; alt=&quot;A picture from the flight&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=xm-EM7dGLg8&quot; rel=&quot;noreferrer&quot;&gt;Video&lt;/a&gt;&#xA;Please watch in HD to best notice the phenomenon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It seems to be coming from the AC vents of aircraft. I think it's a quite common phenomenon as the cabin crew didn't even pay any attention to this. &#xA;But I saw it for the first time. What is this?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft Details : &lt;a href=&quot;https://planefinder.net/data/aircraft/VT-IDE&quot; rel=&quot;noreferrer&quot;&gt;VT-IDE&lt;/a&gt; (A 3.5 year old A320)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The departure location was &lt;a href=&quot;https://en.wikipedia.org/wiki/Biju_Patnaik_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;Bhubaneshwar&lt;/a&gt; and the approximate weather was:&lt;br&gt;&#xA;Temperature : 28 °C&lt;br&gt;&#xA;Humidity ~ 85%&lt;br&gt;&#xA;Clear Sky, good visibility&lt;/p&gt;&#xA;" OwnerUserId="8482" LastEditorUserId="1467" LastEditDate="2018-09-05T10:48:42.157" LastActivityDate="2020-12-12T15:00:21.107" Title="What is this white smoke like thing, seen inside the cabin before takeoff?" Tags="&lt;aircraft-design&gt;&lt;cabin-design&gt;&lt;cabin&gt;" AnswerCount="3" CommentCount="1" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="29069" PostTypeId="2" ParentId="29068" CreationDate="2016-06-07T05:57:11.490" Score="69" Body="&lt;h3&gt;Direct answer&lt;/h3&gt;&#xA;&lt;p&gt;Air conditioning causes a large drop in cabin temperature, air humidity present in the air condensates into water droplets. It is similar to mist, fog and clouds. If water droplets enter in contact with a solid they form dew and moisture. Accurately, it is an &lt;a href=&quot;https://en.wikipedia.org/wiki/Aerosol&quot; rel=&quot;nofollow noreferrer&quot;&gt;aerosol&lt;/a&gt; of water droplets.&lt;/p&gt;&#xA;&lt;p&gt;Water droplets appear in air when air temperature is lowered below its &lt;em&gt;dew point&lt;/em&gt; (see further down). This phenomenon is exactly the same than when a freezer is opened and air over the freezer is in contact with cold air from the freezer tank:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/N8GtE.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/N8GtE.jpg&quot; alt=&quot;Condensation over open freezer&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Marcellus ̶̶̶̶̶̶̶̶ freezer. &lt;a href=&quot;https://www.homestratosphere.com/types-of-freezers/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;&lt;/sup&gt;.&lt;/p&gt;&#xA;&lt;h3&gt;Quick explanation&lt;/h3&gt;&#xA;&lt;p&gt;In your case, before air conditioning is started the cabin is filled with air from the outside, which happens to be warm and nearly saturated in water vapor. The ambient temperature is close to the dew point. The injection of colder conditioned air in the cabin decreases the temperature around the AC vents (&lt;em&gt;inlet air&lt;/em&gt; on the picture below):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LBdU9.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LBdU9.png&quot; alt=&quot;Air circulation in large pressurized aircraft&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Air circulation in large pressurized aircraft, from &lt;a href=&quot;https://aviation.stackexchange.com/a/72440/3201&quot;&gt;this answer&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The temperature quickly goes below the dew point causing invisible gas (water vapor) condensation into visible liquid water droplets (fog).&lt;/p&gt;&#xA;&lt;p&gt;Due to the limited instantaneous capacity of the air conditioning system, the temperature is decreased only around the AC vents, not in the whole cabin. When the water droplets mix with the warmer air in the rest of the cabin, they immediately return to the gaseous form (vapor), and doing this they also make this air a bit colder (&lt;a href=&quot;https://en.wikipedia.org/wiki/Evaporation&quot; rel=&quot;nofollow noreferrer&quot;&gt;evaporative cooling&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;As pointed out by @JanHudec the humidity level must be kept low during the flight to prevent structure oxidation. Humid air from the cabin returns &lt;a href=&quot;https://aviation.stackexchange.com/q/26039/3201&quot;&gt;through the decompression panels&lt;/a&gt; to the air conditioning system where it is mixed with dryer air from the packs. After some cycles the cabin air is rather dry and condensation doesn't occur anymore.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=GSjcf50NnNo&quot; rel=&quot;nofollow noreferrer&quot;&gt;Another case&lt;/a&gt; of condensation:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.youtube.com/watch?v=GSjcf50NnNo&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ehKjK.jpg&quot; alt=&quot;Water Condensation in Aicraft&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;h3&gt;Detailed explanation&lt;/h3&gt;&#xA;&lt;p&gt;&lt;strong&gt;Why does water vapor condense?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The quantity of water vapor in air is named water saturation ratio (or &lt;a href=&quot;https://en.wikipedia.org/wiki/Relative_humidity&quot; rel=&quot;nofollow noreferrer&quot;&gt;relative humidity&lt;/a&gt;) and is expressed as a percentage: 0% for dry air, 100% for air fully saturated. Saturated air cannot contain more water vapor. If vapor is added then it immediately condenses into visible water droplets.&lt;/p&gt;&#xA;&lt;p&gt;Saturation occurs at certain combinations of temperature and pressure. For a given pressure, the higher the temperature, the larger the quantity of vapor than can be present without condensation. So condensation can occur when the temperature decreases.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Psychrometrics&quot; rel=&quot;nofollow noreferrer&quot;&gt;Psychrometrics&lt;/a&gt;, the branch of physics studying how liquids and solids boil or condense, revolves around the notion of &lt;a href=&quot;https://en.wikipedia.org/wiki/Vapor_pressure&quot; rel=&quot;nofollow noreferrer&quot;&gt;equilibrium vapor pressure&lt;/a&gt;, but for us mere mortals, the notion of dew point is more practical.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Dew point&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The quantity of vapor air can contain before being saturated is called its &lt;em&gt;water vapor capacity&lt;/em&gt;, it increases exponentially with temperature:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gKaRK.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gKaRK.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;https://www4.uwsp.edu/geo/faculty/lemke/geog101/text_notes/07a_saturation_curve.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Let's define two cases:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Full saturation: If the quantity of vapor is the maximum allowed for the current temperature (100% relative humidity), decreasing the temperature or adding vapor will cause some vapor to condensate into water.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Partial saturation: If air is not fully saturated, there is a (lower) temperature for which it becomes saturated. This temperature is referred to as &lt;em&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Dew_point&quot; rel=&quot;nofollow noreferrer&quot;&gt;dew point&lt;/a&gt;&lt;/em&gt;. So whatever the current temperature, fog can be created by decreasing the temperature until the dew point is reached.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;For sake of accuracy: When water vapor is present in air, it is continuously condensed and evaporated. The dew point is the point where condensation occurs at a greater rate than evaporation and water droplets start accumulating.&lt;/p&gt;&#xA;&lt;p&gt;Whether fog will form depends on the the dew point spread, that is the difference between current temperature and dew point. When the spread is large, the change in humidity or in temperature must be large. In your case, the spread is small, because air is wet and temperature is high.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Bhubaneshwar case&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Before air conditioning system is started, cabin air is the same than at the airport: 28°C and 85% humidity. AC is going to inject air at 20°:&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Quantity of vapor for 85% RH at 28°C is 23g per kg (85% * 27).&lt;/li&gt;&#xA;&lt;li&gt;Vapor capacity at 20°: 17g per kg.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;When air is injected and temperature is decreased to 20° around the vents, air becomes fully saturated, and the 6g of vapor in excess per kg of air are condensed into fog.&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/moLJZ.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/moLJZ.png&quot; alt=&quot;Cabin air relative humidity and AC fog&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;sup&gt;Cabin air relative humidity and AC fog&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;This air returns to the AC system, and is mixed with air from packs which condition air entering the cabin at the 20% RH targeted for the flight. The 13.6g/kg of vapor in excess (for 20% RH) are progressively extracted by outflow valves, which regulate pressure in the cabin by releasing overboard as much air as packs push in. After some cycles, air contains only 3.4g/kg of vapor (the cycle is simplified, actually we would also account for passengers perspiration and breathing, fog re-vaporization and AC air humidity)&lt;/p&gt;&#xA;&lt;p&gt;For typical cabin of 150m&lt;sup&gt;3&lt;/sup&gt; containing about 175 kg of air, 3.5 kg of water are extracted.&lt;/p&gt;&#xA;&lt;p&gt;Fog in the aircraft is indeed a problem, fog outside the aircraft is another one as visibility is strongly impeded. It requires flying using &lt;em&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/12208/3201&quot;&gt;Instrument Flying Rules&lt;/a&gt;&lt;/em&gt; (IFR). IFR is allowed only with a specific pilot rating and aviation certification. Knowing the dew point is important to plan a flight, in particular to know whether IFR will be required. Therefore the dew point is measured and published as aeronautical information.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Measuring the dew point&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;The dew point may be determined with a &lt;a href=&quot;https://en.wikipedia.org/wiki/Hygrometer#Psychrometers&quot; rel=&quot;nofollow noreferrer&quot;&gt;psychrometer&lt;/a&gt; (a system with dry and wet thermometers):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/HaGaN.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/HaGaN.jpg&quot; alt=&quot;Psychrometers&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Whirling (&lt;a href=&quot;https://www.youtube.com/watch?v=4nwZ3I9MwzA&quot; rel=&quot;nofollow noreferrer&quot;&gt;how to use it&lt;/a&gt;) and digital psychrometers&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;Pressure, dry and wet temperatures, dew point and relative humidity are linked by the mean of vapor pressure. By knowing three elements, the two other can be determined. So knowing pressure, dry temperature and wet temperature allows to determine the dew point. It exists precalculated charts (&lt;a href=&quot;https://i.stack.imgur.com/jywHk.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;Mollier diagrams&lt;/a&gt;) to read dew point directly. There are also &lt;a href=&quot;https://afim-luchtdroging.com/en/mollier-chart-air-calculator/&quot; rel=&quot;nofollow noreferrer&quot;&gt;online calculators&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;Here is a vertical profile of the temperature and moisture information (&lt;a href=&quot;https://en.wikipedia.org/wiki/Emagram&quot; rel=&quot;nofollow noreferrer&quot;&gt;emagram&lt;/a&gt;) collected by a radiosonde in Ireland:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hWz3W.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hWz3W.png&quot; alt=&quot;Emagram from Valentia Observatory (Ireland)&quot; /&gt;&lt;/a&gt;&lt;br /&gt;&#xA;&lt;sup&gt;Emagram from Valentia Observatory (Ireland). Source &lt;a href=&quot;http://www.meteociel.fr/observations-meteo/sondage.php?map=1&quot; rel=&quot;nofollow noreferrer&quot;&gt;meteociel.fr&lt;/a&gt;&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The vertical scale is the pressure (hPa on the left, equivalent altitude on the right) and temperature is on an oblique scale, with the quantity of water at saturation for this temperature. The dry temperature is shown in read, the wet temperature in blue, and the computed dew point in cyan. When the dew point curve is close to the temperature, moisture is hight (%RH on altitude scale) and cloud/fog can occur (like under 1,600 m for this example).&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Dew point and fog/mist information&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;http://w1.weather.gov/obhistory/KLAX.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;KLAX ASOS report&lt;/a&gt;:&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CowAN.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CowAN.png&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;As previously mentioned, when the dew point is close to the ambient temperature and the humidity percentage is high, the visibility is low and fog occurs.&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;Common examples of condensation&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Frost around the freezer pipes: Air with water vapor enter the fridge when the door is open. When air starts to be cooled below the dew point by the pipes, condensation occurs and ice forms around them.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air exhaled when the weather is cold. Air in our lungs is not saturated due to the high body temperature, but becomes saturated when it starts cooling.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Air saturated by water vapor coming from a pressure cooker.&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;As pointed out by @RyanMortensen, saturated air on car windows (when the temperature decreases during the night, or when air is saturated without temperature change, because there is more water/rain in the air that can be evaporated naturally -- Increasing car temperature above the dew point is the solution).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Fog and clouds formation: Fog because the ground is colder than the surrounding atmosphere (early in the morning), cloud because air is cooled below the dew point while it climbs (pressure and suddenness play also a role).&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Dew :-)&lt;/p&gt;&#xA;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&lt;p&gt;&lt;strong&gt;When water vapor changes into ice&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;When the dew point is below 0°C, water vapor is not condensing into water droplets, it is converted directly into ice crystals (&lt;a href=&quot;https://en.wikipedia.org/wiki/Frost&quot; rel=&quot;nofollow noreferrer&quot;&gt;frost&lt;/a&gt;).&lt;/p&gt;&#xA;&lt;p&gt;This effect is particularly dangerous and can lead to &lt;a href=&quot;https://copanational.org/en/2020/06/11/carb-ice-likely-brought-down-cessna-tsb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;icing in the carburetor&lt;/a&gt; of a piston engine. This condition can happen in areas of low pressure and low temperature, commonly created by the sudden pressure drop in the &lt;a href=&quot;https://www.easa.europa.eu/sites/default/files/dfu/EGAST_GA5-Piston-Engine-Icing-final.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;throttle venturi&lt;/a&gt;, due to &lt;a href=&quot;https://en.wikipedia.org/wiki/Venturi_effect&quot; rel=&quot;nofollow noreferrer&quot;&gt;venturi effect&lt;/a&gt; and the temperature drop due to &lt;a href=&quot;https://sciencing.com/evaporation-cause-cooling-5315235.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;fuel vaporization&lt;/a&gt;.&lt;/p&gt;&#xA;&lt;p&gt;For a typical piston engine, this effect is centered on a external temperature around 10°C but extends to a large range of temperature when the engine is slowed down (descent):&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/Cejap.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Cejap.png&quot; alt=&quot;Induction icing conditions&quot; /&gt;&lt;/a&gt;&#xA;&lt;sup&gt;Induction icing conditions&lt;/sup&gt;&lt;/p&gt;&#xA;&lt;p&gt;The remedy to carburetor induction icing is to &lt;a href=&quot;https://en.wikipedia.org/wiki/Carburetor_heat&quot; rel=&quot;nofollow noreferrer&quot;&gt;heat the carburetor&lt;/a&gt; and raise the due point to a safe area, especially when descending.&lt;/p&gt;&#xA;&lt;p&gt;For jet engines, induction icing (not to be confused with &lt;a href=&quot;https://www.skybrary.aero/index.php/High_Level_Ice_Crystal_Icing:_Effects_on_Engines&quot; rel=&quot;nofollow noreferrer&quot;&gt;flying in atmosphere with ice crystals&lt;/a&gt; or supercooled water droplets) can cause ice to form at the engine inlet. Blocks of ice can then break, causing damage to blades, compressor stall and/or combustor flameout. It can also cause &lt;a href=&quot;https://www.skybrary.aero/index.php/Engine_Pressure_Ratio_(EPR)&quot; rel=&quot;nofollow noreferrer&quot;&gt;EPR probe (PT2)&lt;/a&gt; reading errors and subsequent &lt;a href=&quot;https://www.skybrary.aero/index.php/Full_Authority_Digital_Engine_Control_(FADEC)&quot; rel=&quot;nofollow noreferrer&quot;&gt;FADEC&lt;/a&gt; fatal behavior.&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2020-12-12T15:00:21.107" LastActivityDate="2020-12-12T15:00:21.107" CommentCount="14" ContentLicense="CC BY-SA 4.0" />
  <row Id="29070" PostTypeId="2" ParentId="29067" CreationDate="2016-06-07T06:08:23.983" Score="3" Body="&lt;p&gt;Theoretically, they could go by NOTAM category and select every NOTAM that falls along their planned route of flight (and planned alternates, if applicable), along with a few NOTAMs that warrant a general check regardless e.g. Presidential TFRs anywhere near their route of flight (and I use the term &quot;near&quot; very loosely; I'd check for Presidential TFRs anywhere in the state, and even in the adjacent state if close to the border).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More practically, it depends from pilot to pilot, but if you file a flight plan and ask for a briefing (which you really should for all but the most local of flights), you can ask the briefer to check for NOTAMs in effect along your route of flight to leverage their software to filter out unnecessary info.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More recently, we've also got a plethora of digital flight planning tools that can access the FAA NOTAM databases and pull down any and all relevant NOTAMs according to the filters you set.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At a minimum, you'd want to make sure you might want to check NOTAMs at your airports of departure and destination, along with your alternates and any TFRs. Checking NOTAMs for any navigational equipment you're planning to use (e.g. VOR/DME stations under maintenance, RAIM outages, etc.) is also a good idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Ultimately, however, it's up to the PIC to determine which NOTAMs are relevant and should be reviewed and which ones are not. All part of the position's prerogatives. &lt;/p&gt;&#xA;" OwnerUserId="7568" LastActivityDate="2016-06-07T06:08:23.983" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29071" PostTypeId="2" ParentId="29067" CreationDate="2016-06-07T06:19:05.427" Score="4" Body="&lt;p&gt;A quick lookup tool is &lt;a href=&quot;https://pilotweb.nas.faa.gov/PilotWeb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;PilotWeb&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The pilots may receive NOTAMS during flight briefing.  The best way to ensure that you are getting proper NOTAMS is to request all NOTAMS for the route of flight you have filed when you speak with the flight briefer.  The briefers are trained professionals, and they know what NOTAM information to provide to pilots, but &lt;strong&gt;it must be requested!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA says this in regards to a &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/alaska/fai/pfpwb/&quot; rel=&quot;nofollow noreferrer&quot;&gt;standard briefing:&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Notices to Airmen (NOTAMs)&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) Available NOTAM (D) information pertinent to the proposed flight,&#xA;  including special use airspace (SUA) NOTAMs for restricted areas,&#xA;  aerial refueling, and night vision goggles (NVG).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- Other SUA NOTAMs (D), such as military operations area (MOA),&#xA;  military training route (MTR), and warning area &lt;strong&gt;NOTAMs, are considered&#xA;  “upon request” briefing items&lt;/strong&gt; as indicated in paragraph 7-1-4b10(a).&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) Prohibited Areas P-40, P-49, P-56, and the special flight rules&#xA;  area (SFRA) for Washington, DC.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) FSS briefers do not provide FDC NOTAM information for special&#xA;  instrument approach procedures &lt;strong&gt;unless specifically asked.&lt;/strong&gt; Pilots&#xA;  authorized by the FAA to use special instrument approach procedures&#xA;  &lt;strong&gt;must specifically request FDC NOTAM information&lt;/strong&gt; for these procedures.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- NOTAM information may be combined with current conditions when&#xA;  the briefer believes it is logical to do so.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;NOTE- NOTAM (D) information and FDC NOTAMs which have been published&#xA;  in the Notices to Airmen Publication are not included in pilot&#xA;  briefings &lt;strong&gt;unless a review of this publication is specifically&#xA;  requested by the pilot.&lt;/strong&gt; For complete flight information you are urged&#xA;  to review the printed NOTAMs in the Notices to Airmen Publication and&#xA;  the A/FD in addition to obtaining a briefing.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;If someone is performing a self-brief via &lt;a href=&quot;https://www.1800wxbrief.com/Website/#!/&quot; rel=&quot;nofollow noreferrer&quot;&gt;1800wxbrief.com&lt;/a&gt;, which is the best internet briefing site in my personal opinion (&lt;em&gt;because it will tell you if you make a mistake rather than purge your flight plan without telling you&lt;/em&gt;), they can see NOTAMS invoked by relevance to their proposed flight path.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to be &lt;em&gt;sure&lt;/em&gt; you're getting everything, call 1-800-WXBRIEF via phone and file that way and &lt;strong&gt;request&lt;/strong&gt; NOTAMS from the briefer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One last thing that needs to be reiterated here:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&quot;&lt;a href=&quot;https://aviation.stackexchange.com/questions/29037/what-is-the-difference-between-distant-d-notams-local-l-notams-and-fdc-nota&quot;&gt;This&#xA;  question&lt;/a&gt;&#xA;  talks about the many types [of NOTAMS].&quot;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;There are &lt;a href=&quot;http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/alaska/fai/notam/ntm_overview/&quot; rel=&quot;nofollow noreferrer&quot;&gt;various classifications of NOTAMS&lt;/a&gt;, but for all intents and purposes in the civilian world, we have two types of NOTAMS; Distant-(D) and FDC.  &lt;em&gt;That's it.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Civilians haven't had local NOTAMS in the US since 2008 when an advisory circular announced that they were being packaged into NOTAM-(D)s&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.623" LastActivityDate="2016-06-07T06:19:05.427" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29073" PostTypeId="1" CreationDate="2016-06-07T09:22:36.153" Score="4" ViewCount="676" Body="&lt;p&gt;I've noticed on many military and commercial jets, the trailing edge control surfaces (ailerons and flaps) are separate from each other.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why is this? Can't both serve the same function? It would save weight and complexity if one combined control surface ran the length of the trailing edge, instead of being split in half.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A particular example I found is the &lt;a href=&quot;https://en.wikipedia.org/wiki/Convair_F-102_Delta_Dagger#Specifications_.28F-102A.29&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-102 Delta Dagger&lt;/a&gt;. There's no conventional tail to experience disrupted airflow, so why have separate ailerons and flaps?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/YxZfE.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/YxZfE.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A similar idea that I know exists is the V-tail, such as in the F-117, which has &quot;ruddervators&quot;---combined elevators/rudders. It can still control yaw and pitch at the same time by somehow averaging the deflections. Presumably, combining and averaging ailerons and flaps should be even simpler, since they're both deflecting on the same axis.&lt;/p&gt;&#xA;" OwnerUserId="3674" LastActivityDate="2019-08-15T01:00:51.517" Title="Why are trailing-edge control surfaces usually split?" Tags="&lt;aircraft-design&gt;&lt;flaps&gt;&lt;control-surfaces&gt;&lt;ailerons&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29074" PostTypeId="2" ParentId="29073" CreationDate="2016-06-07T10:12:24.617" Score="5" Body="&lt;p&gt;Same reason you have split ailerons on most big airliners. The inboard surfaces deflect at higher speeds and the outboard ones are locked, reducing the twisting (torque) forces on the wings. It also allows for finer control (in &lt;a href=&quot;https://en.wikipedia.org/wiki/Fly-by-wire&quot; rel=&quot;noreferrer&quot;&gt;fly-by-wire&lt;/a&gt; cases) as well. Like a lever, a small deflection of the outboard surface results is higher rate pitch/roll (in this delta wing &lt;a href=&quot;https://en.wikipedia.org/wiki/Aileron#Combinations_with_other_control_surfaces&quot; rel=&quot;noreferrer&quot;&gt;elevon&lt;/a&gt; example) compared to same deflection of the inboard surface.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastActivityDate="2016-06-07T10:12:24.617" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29075" PostTypeId="1" AcceptedAnswerId="29078" CreationDate="2016-06-07T11:07:23.010" Score="20" ViewCount="3385" Body="&lt;p&gt;How can the IATA &lt;a href=&quot;http://airlines.iata.org/data/safer-than-ever&quot; rel=&quot;noreferrer&quot;&gt;claim&lt;/a&gt; that the year 2015 saw no accidental hull losses, if we had the &lt;a href=&quot;https://en.wikipedia.org/wiki/Germanwings_Flight_9525&quot; rel=&quot;noreferrer&quot;&gt;Germanwings Flight 9525&lt;/a&gt; accident? Even if this one is not considered &quot;an accident&quot; then there are &lt;a href=&quot;https://en.wikipedia.org/wiki/Category:Aviation_accidents_and_incidents_in_2015&quot; rel=&quot;noreferrer&quot;&gt;a few others&lt;/a&gt; (for instance &lt;a href=&quot;https://en.wikipedia.org/wiki/Metrojet_Flight_9268&quot; rel=&quot;noreferrer&quot;&gt;Metrojet Flight 9268&lt;/a&gt;) that can be clearly taken as &quot;accidental hull losses&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;How should I understand &quot;accidental hull loss&quot; exactly, or what is it that I am missing?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;EDIT&lt;/strong&gt;: &lt;em&gt;While I agree, that I may be missing some certain points and the general definition given in IATA article and while I agree with all answers and comments given here, I think that on contrary &lt;a href=&quot;https://en.wikipedia.org/wiki/Carson_Air_Flight_66&quot; rel=&quot;noreferrer&quot;&gt;Carson Air Flight 66&lt;/a&gt; fits pretty perfectly into &quot;accidental hull loss&quot; definition. It is from 2015 and it is a bit interesting, why IATA &quot;forgot&quot; about it in their report?&lt;/em&gt;&lt;/p&gt;&#xA;" OwnerUserId="3230" LastEditorUserId="3230" LastEditDate="2016-06-08T14:13:54.977" LastActivityDate="2019-05-09T11:38:44.037" Title="How exactly should I understand the term &quot;accidental hull loss&quot;?" Tags="&lt;terminology&gt;&lt;iata&gt;" AnswerCount="3" CommentCount="7" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29076" PostTypeId="2" ParentId="29075" CreationDate="2016-06-07T11:14:57.263" Score="10" Body="&lt;p&gt;From the IATA link:&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;[W]e were all shocked and horrified by two deliberate acts—the destruction of Germanwings 9525 and Metrojet 9268.&lt;/p&gt;&#xA;&lt;p&gt;They are not, however, included in the accident statistics as they are classified as deliberate acts of unlawful interference.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;RE comment:&lt;/p&gt;&#xA;&lt;p&gt;&lt;strong&gt;How is it reasonable to talk about safety if we exclude non-jet, non-accidental and non-passenger flights, that crashed?&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;If no passengers (e.g., Carson Air) and/or if no IATA member is involved, then it is beyond IATA's scope, which is a trade association for most (but not all) air carriers. As far as IATA is concerned, 2015 was a good year.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2019-05-09T11:38:44.037" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="29077" PostTypeId="2" ParentId="29073" CreationDate="2016-06-07T11:24:29.597" Score="4" Body="&lt;p&gt;There is no &quot;usually&quot; here. For every aircraft with split control surfaces you come up with, I believe it would be possible to come up with an aircraft that either has one combined control surface (eg F-16 has flaperons), an aircraft that has some kind of a combination (eg F-18, which has an inboard flap and an outboard flaperon as can be seen here - warning headphones users - &lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/fNInwpnIdS4?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;) &lt;/p&gt;&#xA;&#xA;&lt;p&gt;or even an aircraft that doesn't even use ailerons (eg F-14, that only uses elevons and spoilers on the top of the wing for roll authority).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What you may consider to be less complex structurally might end up being more complex as much as the Fly-By-Wire software logic is concerned.&lt;/p&gt;&#xA;" OwnerUserId="3363" LastEditorUserId="5517" LastEditDate="2016-06-07T15:49:36.467" LastActivityDate="2016-06-07T15:49:36.467" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29078" PostTypeId="2" ParentId="29075" CreationDate="2016-06-07T11:49:03.190" Score="21" Body="&lt;p&gt;Both the MetroJet and GermanWings incidents were deliberate acts of destruction, not &lt;em&gt;accidents&lt;/em&gt; in any common understanding of the word, or indeed in the sense defined by the Convention on International Civil Aviation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Chicago_Convention_on_International_Civil_Aviation&quot;&gt;Chicago Convention&lt;/a&gt;, as it's also known, defines an &lt;em&gt;accident&lt;/em&gt; as:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An occurrence associated with the operation of an aircraft [...] in which  [...] a person is fatally or seriously injured [...] &lt;strong&gt;except when the injuries are [...] inflicted by other persons&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My emphasis added - see &lt;a href=&quot;http://www.iprr.org/manuals/Annex13.html&quot;&gt;Annexe 13 of the Convention&lt;/a&gt; for the full definition - it's quite dry but interesting, if you're interested in that kind of thing. The exceptions it lists are illuminating.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Deliberate acts and &quot;incidents&quot;&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;I do think that the definitions in the &lt;em&gt;Annexe&lt;/em&gt; are slightly odd. You'd think that the deliberate destruction of an airliner in flight should be called an &lt;em&gt;incident&lt;/em&gt;, but an &lt;em&gt;incident&lt;/em&gt; is apparently:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An occurrence, other than an accident, [affecting safety].&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;I guess that's one way of describing a bombing or deliberate crash into terrain... but then there's also a &lt;em&gt;Serious incident&lt;/em&gt; which is merely:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;An incident involving circumstances indicating that an accident &lt;em&gt;nearly&lt;/em&gt; occurred. [my emphasis again]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So that would make the GermanWings and MetroJet cases &lt;em&gt;incidents&lt;/em&gt;, but not &lt;em&gt;serious incidents&lt;/em&gt;!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;However&lt;/strong&gt;: since &quot;Appendix 7&quot; of the &lt;em&gt;ICAO Accident/Incident Reporting Manual&lt;/em&gt; lists &quot;types of incident&quot;, and deliberate acts of destruction are not amongst them, I can only deduce that they are classified as neither &lt;em&gt;incidents&lt;/em&gt; nor &lt;em&gt;accidents&lt;/em&gt;. I am not sure exactly what the official terminology is for them.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-07T11:49:03.190" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="29080" PostTypeId="2" ParentId="29054" CreationDate="2016-06-07T13:41:27.720" Score="2" Body="&lt;p&gt;The answer depends on which aerodrome you are talking about, and can be found in the UK AIP: &lt;a href=&quot;http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&amp;amp;task=blogcategory&amp;amp;id=165&amp;amp;Itemid=3.html&quot; rel=&quot;nofollow&quot;&gt;http://www.nats-uk.ead-it.com/public/index.php%3Foption=com_content&amp;amp;task=blogcategory&amp;amp;id=165&amp;amp;Itemid=3.html&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Click eAIP to open the electronic AIP. In the left menu, open the AD 2 Aerodromes section and navigate to the aerodrome in question. Then open the AD 2.17 section of that aerodrome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In AD 2.17, airspaces related to the specific aerodrome are listed. Column 1 contains the airspace designator and lateral limits. Column 4 contains the responsible ATS unit.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As an example - the Birmingham (EGBB) CTR is controlled by Birmingham Approach.&lt;/p&gt;&#xA;" OwnerUserId="14957" LastActivityDate="2016-06-07T13:41:27.720" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29081" PostTypeId="2" ParentId="24456" CreationDate="2016-06-07T13:50:35.847" Score="10" Body="&lt;p&gt;The transportation industry tends to use specific phrases to describe events of this kind. They are not just euphemisms, but are intended to neutralise the potential for drama, speculation, voyeurism that can surround them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the UK, for example, you will sometimes hear that an London Underground service has been disrupted by &quot;passenger action&quot;. This means that someone has committed suicide on the rail lines.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As noted in other answers, &quot;the needs of a passenger&quot; means a serious medical issue.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-07T13:50:35.847" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29082" PostTypeId="2" ParentId="28007" CreationDate="2016-06-07T15:44:39.673" Score="2" Body="&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;FCOM: This document has everything the flight crew might need to know about the aircraft during flight. It must be available on board and pilots refer to it for anything they don't want to, or shouldn't, rely on their memory for, mainly performance calculations and troubleshooting. It is provided by the aircraft manufacturer, but customized according to equipment of each particular airframe and SOP of the particular operator.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;FCTM: This document describes what the flight crew must regularly train, usually on the simulator. It does not have to be on board.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;SOP: This document describes the operation side of things. There may be additional restrictions on acceptable clearances, rules for using derated take-off thrust, communication protocol towards cabin crew etc. This is created by the operator. The procedure side of things is usually uniform across the fleet, but there are also restrictions pertaining to particular aircraft. Should be available on board.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;QRH: Basically excerpt from the above documents containing checklists and tables, so they are easy to find when they are needed, usually when things go wrong. Of course, should be on board.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-06-07T15:44:39.673" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29083" PostTypeId="1" CreationDate="2016-06-07T15:44:46.687" Score="11" ViewCount="2148" Body="&lt;p&gt;Following up on &lt;a href=&quot;http://edition.cnn.com/2016/06/02/politics/military-plane-crash/&quot;&gt;recent events involving the Blue Angels and the Thunderbirds&lt;/a&gt;, what is the typical procedure for these teams following a unexpected turnover of a pilot (in this case, a fatal or other serious crash)?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Do these teams have a &quot;B&quot; team in training to pull talent from, or possibly have a larger pilots roster that will rotate in and out throughout the season to pull from?  Maybe even have multiple teams that trade off show duties and training during the season?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;(I assume that the Thunderbirds will just paint up a new plane and give the pilot a good pep talk).&lt;/p&gt;&#xA;" OwnerUserId="15314" LastEditorUserId="1467" LastEditDate="2017-08-14T11:00:42.417" LastActivityDate="2017-08-14T11:00:42.417" Title="What happens to US military demo teams following unexpected pilot turnover?" Tags="&lt;usa&gt;&lt;accidents&gt;&lt;airshow&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29085" PostTypeId="2" ParentId="29041" CreationDate="2016-06-07T16:51:31.243" Score="5" Body="&lt;p&gt;A plane that has just landed is actually in a new and vulnerable condition. The passengers may finally be relaxing because the wings didn't fall off and &lt;a href=&quot;http://www.theguardian.com/us-news/2016/may/07/professor-flight-delay-terrorism-equation-american-airlines&quot; rel=&quot;noreferrer&quot;&gt;the Italian mathematician in has packed away his terrifying scribblings&lt;/a&gt;, but the aircraft has entered a new environment with new risks, and the crew are certainly not thinking &quot;There, done that, work's over.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A stationary or slow-moving aircraft is at risk from a fuel, oil and even other fluid leaks in a way that one that's flying isn't.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A newly-landed aircraft has new, different stresses on its structure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One that's just landed has hot engines, brakes and tyres. Tyres in particular, but also other components, can and do catch fire.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unlike when it's in the air, an aircraft heading to the terminal is in close proximity to buildings and other obstacles, some of which also move around themselves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For any number of reasons aircraft may need to be evacuated, or manoeuvred violently shortly after landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those are not circumstances in which you want 200 people standing up, blocking each other's view of the cabin crew, talking loudly, pulling luggage out of overhead compartments, putting objects in the aisle.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The safe place for people to be is sitting quietly in their seats, until the doors are opened and they are invited to get up and leave.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-07T16:51:31.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29086" PostTypeId="2" ParentId="29083" CreationDate="2016-06-07T17:01:47.450" Score="26" Body="&lt;p&gt;I can't answer for the Blue Angels or the Thunderbirds, but I can for the UK equivalent, the Red Arrows.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Red Arrows have no spare pilots (or 'B team'). The nine pilots on the team fly every display in their 3 year tour. The explanation is that a spare pilot would not fly frequently enough to be current and safe. They do however have the capability to do an 8-plane display (rather than the usual 9) which they can use if a pilot is temporarily incapacitated. They also have a spare plane, something I know also applies to the Thunderbirds.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the event of any kind of serious accident, it is likely that displays would be suspended for at least a while, in order to investigate and also out of respect. If all pilots are available when displays resume everything would be normal, using the spare plane if required. If a pilot was out for a short time they might fly the 8-plane display. The Arrows fly standard planes with minimal modifications, so presumably a new one could be readied fairly quickly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In 2010 when Flt Lt. Ling was injured too badly to continue with display flying he was replaced by a pilot who had already flown with the team in a previous season.&lt;/p&gt;&#xA;" OwnerUserId="289" LastEditorUserId="289" LastEditDate="2016-06-07T19:21:30.617" LastActivityDate="2016-06-07T19:21:30.617" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29087" PostTypeId="1" CreationDate="2016-06-07T17:44:46.763" Score="2" ViewCount="174" Body="&lt;p&gt;A TAF is published 4 times a day at 6 hour intervals. However if you look at the forecasts within a TAF one might be at a 4 hour interval and the next at an 8. Just look at this example:&lt;/p&gt;&#xA;&#xA;&lt;pre&gt;&lt;code&gt;TAF KPDK 071124Z 0712/0812 32009KT P6SM SKC &#xA;FM071600 33011G18KT P6SM FEW045 &#xA;FM080000 32008KT P6SM SKC&#xA;&lt;/code&gt;&lt;/pre&gt;&#xA;&#xA;&lt;p&gt;Why not publish at consistent intervals?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-06-08T05:54:48.763" Title="Why does the TAF provide forecasts at irregular intervals?" Tags="&lt;weather&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29088" PostTypeId="1" CreationDate="2016-06-07T17:52:31.860" Score="0" ViewCount="157" Body="&lt;p&gt;Why are area forecasts, METARs, and TAFs written in an abbreviated manner? I understand that in the beginning, each digit or symbol costs money. However, that is no longer the situation. Why not make an area forecast as clear as possible? Aviators kill themselves because they do not understand the weather. Is there a reason the FAA continues to do this? Can the community of aviators change this?&lt;/p&gt;&#xA;" OwnerUserId="11402" LastActivityDate="2016-06-07T18:26:37.970" Title="Why Do They Continue To Abbreviate Weather Products? Can We As A Community Change This?" Tags="&lt;weather&gt;" AnswerCount="1" CommentCount="2" ClosedDate="2016-06-07T18:30:26.897" ContentLicense="CC BY-SA 3.0" />
  <row Id="29089" PostTypeId="2" ParentId="29087" CreationDate="2016-06-07T17:54:29.560" Score="4" Body="&lt;p&gt;I assume you're referring to the FM (FROM) groups. The TAF itself is published at regular intervals but sometimes the conditions are expected to change significantly in between those times; obviously, the weather doesn't operate on a neat schedule. So the TAF will show the expected time of those changes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.aviationweather.gov/static/help/taf-decode.php#FM&quot; rel=&quot;nofollow&quot;&gt;According to the National Weather Service&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;FROM Group: ie. (FM1600)&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The FM group is used when a rapid change, usually occuring in less&#xA;  than one hour, in prevailing conditions is expected. Typically, a&#xA;  rapid change of prevailing conditions to more or less a completely new&#xA;  set of prevailing conditions is associated with a synoptic feature&#xA;  passing through the terminal area (cold or warm frontal passage).&#xA;  Appended to the FM indicator is the four-digit hour and minute the&#xA;  change is expected to begin and continues until the next change group&#xA;  or until the end of the current forecast.&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;A FM group will mark the beginning of a new line in a TAF report. Each&#xA;  FM group contains all the required elements -- wind, visibility,&#xA;  weather, and sky condition. Weather will be omitted in FM groups when&#xA;  it is not significant to aviation. FM groups will not include the&#xA;  contraction NSW.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-06-07T17:54:29.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29090" PostTypeId="2" ParentId="29088" CreationDate="2016-06-07T18:26:37.970" Score="5" Body="&lt;p&gt;The language of aviation is terse, compressed and intended to leave minimum room for interpretation or misapprehension. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;It makes heavy use of formulas, themselves intended to to be unambiguous, but which are not always obviously and immediately meaningful to those who are unfamiliar with the language. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This is the norm for potentially critical communication in all fields that I'm aware of - the military, medicine and throughout the transportation industry.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The users of this language are trained in it; being familiar with it is an essential part of their competence. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Language, interfaces, procedures and tools in aviation don't need to be user-friendly, they need to be utterly precise, be usable in difficult circumstances, and on every occasion they're used have exactly the same outcome.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's possible that an aviator has failed to understand a weather forecast and died as a result, but a weather reports that allowed themselves the liberty of free expression would kill a lot more than that. &lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-07T18:26:37.970" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29092" PostTypeId="2" ParentId="27701" CreationDate="2016-06-07T19:59:53.317" Score="12" Body="&lt;p&gt;The biggest benefit of a scimitar propeller is the higher operating Mach number that can be achieved. Tip sweep delays the onset of shocks on the propeller and reduces drag at high subsonic speed. The noise reduction is achieved by reducing shocks on the blade tips at the same tip Mach number - supersonic props are known to be &lt;a href=&quot;https://aviation.stackexchange.com/questions/21683/did-the-xf-84h-thunderscreech-really-cause-900-sonic-booms-per-minute?s=1%7C0.8988&quot;&gt;extremely loud&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The major disadvantage is the torsional moment created by the swept back tip. This can be somewhat mitigated by sweeping the inner blade forward which results in the typical scimitar shape. Still, in-blade torsion moments mean that the blade has to be built such that the deformation in flight will result in the desired blade twist. The use of stiff carbon fiber allows to keep this pre-twisting low.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That scimitar propellers have a high blade count is a result of their high operating speed: To keep the tip Mach number low, the diameter must be limited which increases the load on the single blade. Flying fast needs a lot of thrust, so the &lt;a href=&quot;http://www.avweb.com/news/airman/182418-1.html&quot; rel=&quot;noreferrer&quot;&gt;activity factor&lt;/a&gt; (power absorbed by the propeller per blade area) is high. To reduce the local Mach number on the blade, both chord and blade count are increased while the relative thickness of the blade's airfoil is reduced when compared to a conventional propeller. This results in a lower operating lift coefficient on the blades and lower supervelocities which again helps to increase the operating Mach number.&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.880" LastActivityDate="2016-06-08T05:54:18.597" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29093" PostTypeId="2" ParentId="19313" CreationDate="2016-06-07T20:39:12.623" Score="-10" Body="&lt;p&gt;Any aircraft can land on a grass field. It is actually easier and safer to land on a grass field than a hard surface. The reason that hard surface runways are used is because a dirt runway will develop ruts and require frequent resurfacing, but a hard surface can be landed on repeatedly with no change. Also, if you land on dirt it kicks up a lot of dust and possibly rocks which are bad.&lt;/p&gt;&#xA;&lt;p&gt;Landing gear will not &amp;quot;rip off&amp;quot; an aircraft unless it hits an immovable object, like a brick wall. The landing gear is the toughest part of a plane, so if you hit a brick wall what happens is that the plane rips off the landing gear, not the other way around. I know of small planes that have hit steel highway dividers and come to a dead stop. You have to have a very severe sort of accident to pull apart an aircraft from the landing gear. Normally wings and stuff will come off way before the landing gear does. The landing gear is heavily integrated with the fuselage, so they basically act like a unit.&lt;/p&gt;&#xA;&lt;p&gt;Dirt is very good for landing because the aircraft comes to a stop more quickly. With concrete you just keep rolling and rolling, which is much more dangerous. If I had to land off field, I would look for the muddiest place I could find. Shallow water is excellent too for the same reason: it slows you down quickly.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;To respond to some of the asphalt-loving comments... In any off field landing you should ALWAYS land on dirt, grass or mud (even better). Landing on streets and highways is incredibly dangerous because there are cars and people on roads and other dangerous obstacles such as railings, signposts, fire hydrants, traffic lights and highway lights. Also, in any settled areas there will be wires and steel cables strung across the roads which are invisible from the air and can cut a plane in half.&lt;/p&gt;&#xA;&lt;p&gt;People who advise landing off field on asphalt are just power pilots who don't have off field experience, so they don't know what they are talking about. As any glider pilot or bush pilot will tell you grass is way way safer than trying to land on a road. Even at an airport, it is much safer and easier to land on the grass strip at the airport than the runway.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2021-04-29T13:49:39.087" LastActivityDate="2021-04-29T13:49:39.087" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="29094" PostTypeId="2" ParentId="29041" CreationDate="2016-06-07T20:49:43.557" Score="12" Body="&lt;p&gt;Twice, I've had vehicles (the tractors that tow the baggage carts) cut sharply in front of me as I've taxied toward the gate.  The individual driving the tractor was either oblivious or reckless -- either way, foolish in the extreme -- but no matter what his issues are, I'll do everything I can to avert the risk of a collision.  And that means using the wheel brakes that can stop the aircraft when it's moving nearly 200 mph... and using their full braking capability, right now.  If anyone were standing, he'd have a face full of bulkhead or floor before he had an opportunity to react.  If he were retrieving luggage from an overhead bin, the chance that he'd be able to control the bag are probably pretty slight, and now it's a projectile coming down on the back of somebody's head.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Even our Flight Attendants stay seated as we taxi in to the gate, simply because of the risk that the pilot may need to bring the aircraft to an immediate, even violent, stop with no warning.  It's pretty rare, but when it happens, it happens hard.  Taxiing out for takeoff, you've left the congested gate area behind, and this risk is lower, but after landing, you're heading to the most congested area with the greatest opportunity for something or someone to intrude into the path of the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, yes, by all means, please do follow the Flight Attendants' instruction, and example, and remain seated with your seatbelt fastened until we're parked at the gate.  The face or other body parts you save, might be your own!&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-06-07T20:49:43.557" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29095" PostTypeId="1" CreationDate="2016-06-07T21:08:03.373" Score="4" ViewCount="393" Body="&lt;p&gt;I recently saw a very interesting documentary film made in 1980 about a narrowly-averted airline disaster in which the flight crew were incapacitated and a retired pilot, with the help of other crew members and experienced ground controllers, managed to land the plane safely. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The aircraft in the film is a 707, though I was puzzled by some of the interior shots, in which I thought it looked much more like a DC-8 (it's been a very long time since I flew in either). The footage of the cockpit was actually quite baffling, and I really didn't recognise it at all.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What exterior and interior features would help identify the particular 707 variant?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The documentary is apparently quite famous, so perhaps someone even knows the tail number. It's simply called &lt;em&gt;Airplane!&lt;/em&gt; - very informative, and I learned a great deal about the aviation - highly recommended.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="19" LastEditDate="2017-03-19T14:52:27.207" LastActivityDate="2017-03-19T14:52:27.207" Title="How to identify a specific 707 variant?" Tags="&lt;aircraft-identification&gt;&lt;boeing-707&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29096" PostTypeId="1" CreationDate="2016-06-07T21:25:21.903" Score="9" ViewCount="1418" Body="&lt;p&gt;Two or three decades ago, I would experience quite uncomfortable blocking of the eustachian tubes, which would noisily unblock and become blocked once more as the plane descended.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I haven't experienced that in recent years, in which I have been flying on considerably newer aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is this likely to be a change in the cabin environment or my own physiology - that is, have cabin pressures generally increased so that changes during descent are less dramatic, or have I just become older and less susceptible to blocked ears?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Recent airliners such as the 787 and the A350 have much-touted higher cabin pressure levels; has there also been a general increase in standard cabin pressures over the years?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="14197" LastEditDate="2018-06-24T10:27:15.827" LastActivityDate="2018-06-24T10:27:15.827" Title="Has the typical cabin pressure in airliners changed in recent decades?" Tags="&lt;cabin-pressure&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="29097" PostTypeId="2" ParentId="29096" CreationDate="2016-06-07T21:41:29.747" Score="11" Body="&lt;p&gt;Let's take the &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_737&quot; rel=&quot;noreferrer&quot;&gt;Boeing 737&lt;/a&gt; as an example: an airliner that first flew in 1967 and is still being produced, its variants—old to new—indeed show a trend of increasing pressurization capability.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Note that even the 1967 variant had an &lt;strong&gt;automatic controller&lt;/strong&gt; for the cabin pressurization, and the &lt;em&gt;200Adv&lt;/em&gt; and the &lt;em&gt;Classic&lt;/em&gt; shared the same max ceiling of FL370.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The better the engines and the aerodynamics are, the higher they'll fly, and the stronger the aircraft will be made to offer better cabin altitude. However stronger is now easier than in the past thanks to the materials engineering advancements.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;1/200 (&lt;strong&gt;7.5 psi&lt;/strong&gt;) → 200Adv (&lt;strong&gt;7.8 psi&lt;/strong&gt;) → Classic (&lt;strong&gt;8.65 psi&lt;/strong&gt;) → NG (&lt;strong&gt;9.1 psi&lt;/strong&gt;)&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The higher those values, the lower (denser) the cabin altitude is, for a plane flying at the same altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those values are the limits, each variant will use lower values in the day-to-day operations to reduce the stresses.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;SUP&gt;Source of the figures: &lt;a href=&quot;http://www.b737.org.uk/pressurisation.htm&quot; rel=&quot;noreferrer&quot;&gt;b737.org.uk&lt;/a&gt;&lt;/SUP&gt;&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-09-11T22:39:33.170" LastActivityDate="2016-09-11T22:39:33.170" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29098" PostTypeId="2" ParentId="29095" CreationDate="2016-06-08T00:46:24.693" Score="3" Body="&lt;p&gt;Don't know about the interior shots but for the exterior:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In-flight shots use a model, some ground shots use N6723, c/n 18989/492, a TWA 707-131B.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This is from the awesome website &lt;a href=&quot;http://www.impdb.org/index.php?title=Airplane!&quot; rel=&quot;nofollow&quot;&gt;IMPDb Internet Movie Plane database&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-06-08T00:46:24.693" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29099" PostTypeId="2" ParentId="29096" CreationDate="2016-06-08T01:34:40.377" Score="11" Body="&lt;p&gt;No doubt older airlines had a lower max differential pressure as @ymb1 pointed out.  More likely though is the fact that modern aircraft have automatic pressurization systems that are designed for maximum passenger comfort as the cabini altitude climbs and descends.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Older manual pressurization systems required a pilot to monitor and adjust the pressurization system anytime the aircraft changed altitude or power settings.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastActivityDate="2016-06-08T01:34:40.377" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29100" PostTypeId="2" ParentId="29083" CreationDate="2016-06-08T04:22:40.743" Score="2" Body="&lt;p&gt;Similar to what happened in the aftermath of &lt;a href=&quot;http://www.cnn.com/US/9910/28/missing.angel.04/&quot; rel=&quot;nofollow&quot;&gt;this 1999 crash&lt;/a&gt;, I would anticipate that the Navy will bring back one of the former team members to replace Capt. Kuss when the Navy and the team are ready to resume flying.&lt;/p&gt;&#xA;" OwnerUserId="15317" LastActivityDate="2016-06-08T04:22:40.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29101" PostTypeId="1" CreationDate="2016-06-08T04:39:17.457" Score="5" ViewCount="2174" Body="&lt;p&gt;When am I allowed to change my transponder code to 1200?&lt;/p&gt;&#xA;&lt;p&gt;Is it after clearing the boundary of regulatory airspace (ie. airspace requiring radio contact and an operating transponder)?&lt;/p&gt;&#xA;" OwnerUserId="15318" LastEditorUserId="14661" LastEditDate="2021-02-13T07:53:49.650" LastActivityDate="2021-02-13T07:53:49.650" Title="When may I change my transponder code to 1200 when being handled by ATC?" Tags="&lt;faa-regulations&gt;&lt;air-traffic-control&gt;&lt;transponder&gt;&lt;squawk-codes&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="29102" PostTypeId="2" ParentId="29101" CreationDate="2016-06-08T04:55:01.340" Score="10" Body="&lt;p&gt;ATC will tell you something like, &amp;quot;N1234R radar service terminated. Squawk VFR. Frequency change approved; good day&amp;quot; which you will repeat back as an instruction.&lt;/p&gt;&#xA;&lt;p&gt;You do not change from the assigned transponder code until instructed.&lt;/p&gt;&#xA;&lt;p&gt;If you're in a hurry to get away from ATC, you may request to &lt;strong&gt;terminate radar service&lt;/strong&gt; as soon as you are out of their regulatory airspace.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2021-02-13T07:52:19.963" LastActivityDate="2021-02-13T07:52:19.963" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="29103" PostTypeId="2" ParentId="287" CreationDate="2016-06-08T05:41:21.900" Score="4" Body="&lt;p&gt;There is always more that can be added to a topic, I'm answering late here, but there is one thing that no one has pointed out to my unpleasant surprise.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Pilot/Controller Glossary!&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The asker's question says: (My emphasis)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The effect [&lt;em&gt;of declaring that you are a student pilot&lt;/em&gt;] should be that the controller will be more lenient towards&#xA;  the pilot and &lt;strong&gt;speak slower&lt;/strong&gt;.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Alright folks... pull out your FAR/AIM and flip on to the back where the &lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf#page=99&quot; rel=&quot;nofollow&quot;&gt;pilot/controller glossary&lt;/a&gt; is and find the &lt;strong&gt;bolded&lt;/strong&gt; terminology &quot;&lt;strong&gt;SPEAK SLOWER.&lt;/strong&gt;&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf#page=99&quot; rel=&quot;nofollow&quot;&gt;The bottom of this page in this .pdf file of the pilot/controller glossary&lt;/a&gt; is the term.&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;SPEAK SLOWER&lt;/strong&gt;.  Used in verbal communications as a request to reduce speech rate.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The AIM 4-2-4 says:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;c. Student Pilots Radio Identification -&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;The FAA desires to help student pilots in acquiring sufficient practical experience in the environment in which they will be required&#xA;  to operate. To receive additional assistance while operating in areas&#xA;  of concentrated air traffic, student pilots need only identify&#xA;  themselves as a student pilot during their initial call to an FAA&#xA;  radio facility.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;EXAMPLE:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;DAYTON TOWER, THIS IS FLEETWING ONE TWO THREE FOUR, STUDENT PILOT.&lt;/p&gt;&#xA;  &#xA;  &lt;ol start=&quot;2&quot;&gt;&#xA;  &lt;li&gt;This special identification will alert FAA ATC personnel and enable them to provide student pilots with such extra assistance and&#xA;  consideration as they may need. This procedure is not mandatory.&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;My answer here is, yes&lt;/strong&gt;; it is legal to say you are a student pilot even if you aren't, but why do that when you can say, &quot;&lt;em&gt;English isn't my first language. Could you please &lt;strong&gt;SPEAK SLOWER&lt;/strong&gt; for me&lt;/em&gt;?&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Also: no&lt;/strong&gt;, ATC would not deny you entry into class B for saying you're a student.  They may follow-up by asking if you have the required endorsements from your instructor to enter class B.  Then, if you tell them you aren't actually a student, you may just get on their nerves.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Controllers are human, just tell them what your needs are and they will help you.  Read the pilot/controller glossary.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Another &lt;strong&gt;bolded&lt;/strong&gt; term in the pilot/controller glossary for those who may need extra assistance in communication is &quot;&lt;strong&gt;WORDS TWICE&lt;/strong&gt;.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://www.faa.gov/air_traffic/publications/media/pcg.pdf#page=118&quot; rel=&quot;nofollow&quot;&gt;&lt;strong&gt;WORDS TWICE:&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;a. As a request: “Communication is difficult. Please say every phrase&#xA;  twice.” &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;b. As information: “Since communications are difficult, every&#xA;  phrase in this message will be spoken twice.”&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So to add to the above, &quot;&lt;em&gt;English isn't my first language. I request that you &lt;strong&gt;SPEAK SLOWER&lt;/strong&gt; and say &lt;strong&gt;WORDS TWICE&lt;/strong&gt; for me&lt;/em&gt;.&quot;&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-06-08T17:02:26.433" LastActivityDate="2016-06-08T17:02:26.433" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29104" PostTypeId="2" ParentId="29087" CreationDate="2016-06-08T05:54:48.763" Score="4" Body="&lt;p&gt;This is actually very simple. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason is because the conditions shown on a given line are implied to be current until the next line provides a change.  If the conditions forecast in a given line are expected for 3 hours, then the next line will be three hours later.  If it is 5 hours, then the next line will be five hours later.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When you see TEMPO, then those conditions replace the previous FM line, but only for the block of time in the TEMPO, and then it reverts back to the previous FM line's information until a new FM line replaces it for good.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-06-08T05:54:48.763" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29106" PostTypeId="1" AcceptedAnswerId="29140" CreationDate="2016-06-08T12:57:55.480" Score="9" ViewCount="8236" Body="&lt;p&gt;F/A-18, F-22 Raptor have a horizontal tailplane as well as canted rudders? Why can't the horizontal tailplane done away with (as in the F-117) and have only the ruddervators for pitch control?&lt;a href=&quot;https://i.stack.imgur.com/g4e6Q.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/g4e6Q.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="15311" LastEditDate="2017-12-21T11:24:01.790" LastActivityDate="2017-12-21T11:24:01.790" Title="Why do the F/A-18 and the F-22 Raptor have horizontal stabilizer as well as canted rudders for pitch control?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;rudder&gt;&lt;f-22&gt;&lt;f-18&gt;" AnswerCount="4" CommentCount="1" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29107" PostTypeId="1" AcceptedAnswerId="29111" CreationDate="2016-06-08T13:00:20.027" Score="4" ViewCount="15112" Body="&lt;p&gt;Why is gold used in the canopy of the F-22 Raptor?&lt;/p&gt;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/RPn77.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/RPn77.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="13133" LastEditorUserId="14897" LastEditDate="2021-05-06T21:04:21.673" LastActivityDate="2021-05-06T21:04:21.673" Title="Why does the canopy of the F-22 Raptor have a golden tinge?" Tags="&lt;aircraft-design&gt;&lt;f-22&gt;&lt;canopy&gt;" AnswerCount="1" CommentCount="1" ClosedDate="2016-06-08T16:06:58.943" ContentLicense="CC BY-SA 3.0" />
  <row Id="29108" PostTypeId="2" ParentId="29101" CreationDate="2016-06-08T13:07:22.700" Score="-4" Body="&lt;p&gt;Normally, as a courtesy, you terminate radar service by notifying ATC in a handshake as in Mortensen's answer. In most cases this never happens, because as soon as you leave their zone ATC will terminate service unilaterally--you don't have to ask for it.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying under IFR rules in any airspace except G, you must have a clearance and be using the code currently assigned to you under the clearance.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you are flying VFR, you normally use code 1200. You can change to 1200 whenever you want, but if you previously had a clearance, you will immediately lose your clearance when you switch to 1200.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Therefore, the general principle is that you can switch to 1200 whenever you are flying VFR and do not require a clearance to be where you are. In class B, C, and D you are required to be in &quot;voice contact&quot; with ATC, which could be construed to require a handoff. In class E you are only required to be in voice contact if you are in the vicinity of a towered airport, in which case you have to be in voice contact with the tower (not ATC). So, basically what this means is that if you are in G or E (not near an airport) you can go to 1200 whenever you want. In B, C, D you should always do signoffs (&quot;Cessna 5678 Golf terminating radar service&quot;). If you are in an area that requires a clearance, you must get permission to terminate radar service.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, your own statement is basically correct: once you leave a radio-contact required area, you are free to go VFR. Note that if you abandon a flight plan and go VFR without notifying ATC, even if you are in a radio-free zone, they can get miffed about that because it messes up their rack, so it is always a good practice to explicitly terminate your service/flight plan before switching to VFR and going numberless.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example: You are flying VFR through a restricted military operating area and have a clearance to do so. You must stay on code as long as you are in the restricted area, because you require a clearance to be there.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastEditorUserId="1378" LastEditDate="2016-06-08T16:05:57.520" LastActivityDate="2016-06-08T16:05:57.520" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="29109" PostTypeId="1" CreationDate="2016-06-08T13:09:05.823" Score="5" ViewCount="465" Body="&lt;p&gt;Supposing, after a &quot;bad&quot; landing, performing a high vertical speeed, the crew, unintentionally, activates the ELT, sending the signs to the sattelites, warning the rescue and team about the &quot;accident&quot;, that does not happen.&#xA;Would the fees for the services be payed?&#xA;Is there any penalty for the crew or company?&lt;/p&gt;&#xA;" OwnerUserId="14354" LastActivityDate="2019-06-20T19:32:18.093" Title="What would happen if the Emergency Locator Transmitter was activated wrongly?" Tags="&lt;search-and-rescue&gt;" AnswerCount="2" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29110" PostTypeId="2" ParentId="23620" CreationDate="2016-06-08T13:11:29.067" Score="2" Body="&lt;p&gt;The Suntoucher solar aircraft design looks fine to me. A key note: this is a solar electric powered aircraft using an AC electric motor to turn the prop.  Therefore the stinger section of the fuselage would contain batteries, adding much weight in the area of the wing, putting the CG near the prop on the wing side. Also with the prop mounted, and spinning on (around) the stinger part of the fuselage applying a pusher force on the crew pod, you need to strengthen the connection from the wing to the crew pod; thus the outriggers from the canards to the wing will carry the force and stabilize the wing&lt;/p&gt;&#xA;" OwnerUserId="15322" LastActivityDate="2016-06-08T13:11:29.067" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29111" PostTypeId="2" ParentId="29107" CreationDate="2016-06-08T13:29:00.577" Score="6" Body="&lt;p&gt;In order to reduce the radar cross section (RCS) of the aircraft, the F22 canopies are coated with a thin layer of Indium Tin Oxide (ITO), which gives it a golden tint.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the book &lt;a href=&quot;https://books.google.co.in/books?id=k8skNF7RZVkC&amp;amp;pg=PA48&amp;amp;lpg=PA48&amp;amp;dq=f+22+canopy+gold&amp;amp;source=bl&amp;amp;ots=9daL7xHDfc&amp;amp;sig=VOncilNEnVKkRgDbH_5x0iKEg9o&amp;amp;hl=en&amp;amp;sa=X&amp;amp;ved=0ahUKEwiB6In2wpjNAhUBHJQKHTUrDP44ChDoAQgoMAI#v=onepage&amp;amp;q=f&quot; rel=&quot;nofollow noreferrer&quot;&gt;F-22 Raptor&lt;/a&gt; by Bill Sweetman:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The F22 Raptor canopy ... comprises two sheets of polycarbonate, sandwiched between two layers of optical glass, fusion bonded in an autoclave and drape formed over a canopy blank ... A metallic coating of indium-tin-oxide is added to the canopy to reflect the radar waves, giving it a golden tint.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They are used in stealth aircraft to reduce the RCS. From &lt;a href=&quot;http://www.globalsecurity.org/military/world/stealth-aircraft-material.htm&quot; rel=&quot;nofollow noreferrer&quot;&gt;globalsecurity.org&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A window member composed of a transparent resin or inorganic glass with a transparent conducting film such as gold or ITO (indium tin oxide) coated thereon, is used as an electromagnetic wave shield window for stealth aircraft. Applying such transparent conducting film enables, while maintaining transparency to visible radiation, both a radio wave stealth property which scatters radio waves in various directions so as not to be detected by radar, and an electromagnetic wave shield property which prevents harmful electromagnetic waves, except for visible radiation, from invasion into an aircraft. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This technique is used in other aircraft like the EA6B Prowler and the F-35.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="-1" LastEditDate="2020-01-24T20:43:48.643" LastActivityDate="2020-01-24T20:43:48.643" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="29112" PostTypeId="2" ParentId="29109" CreationDate="2016-06-08T13:31:38.013" Score="2" Body="&lt;p&gt;The ELT guys get a lot of false alarms. About 97% of ELT alerts are false alarms. Most false alarms are generated by bad ELTs on boats.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Neverthless, they chase them all down. The organization that does this is the Civil Air Patrol.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Legally, a person activating false alarm can be held liable for substantial fines, but in practice it is unknown for those fines to be assessed for an accidental alert. If someone was deliberately setting off an ELT, the FCC might attempt to prosecute and assess a fine, which by statute can be as much as $100,000.&lt;/p&gt;&#xA;" OwnerUserId="1378" LastActivityDate="2016-06-08T13:31:38.013" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29113" PostTypeId="2" ParentId="29106" CreationDate="2016-06-08T14:11:01.590" Score="-2" Body="&lt;p&gt;On the F-18, the elevators do not generate enough downward force for takeoff. The rudders provide the additional force required. Visible in this video:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/y3XMUBU6HLc?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice that both rudders are inward on takeoff. Clearly if the elevators do not provide enough pitch control, the rudders along are not going to do it either.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-06-08T14:11:01.590" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29114" PostTypeId="2" ParentId="29109" CreationDate="2016-06-08T14:13:06.770" Score="3" Body="&lt;p&gt;It happens ALL the time. I have been on many airport hunts looking for the airplane with a triggered ELT. You tale a handheld radio and walk through the ramp until you find it.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-06-08T14:13:06.770" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29115" PostTypeId="1" AcceptedAnswerId="29117" CreationDate="2016-06-08T14:23:22.167" Score="21" ViewCount="8538" Body="&lt;p&gt;Story Time:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume, for the sake of the question, that you were piloting a twin engine plane and the right engine, out of the blue, shuts down. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;After realizing it you declare emergency, and explain &lt;strong&gt;very briefly&lt;/strong&gt; to the ATC what is your situation at the moment, and after that you start to work out the checklists (&lt;em&gt;I don't know the right order to proceed on a emergency scenario, but i don't think that it's important to this question&lt;/em&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After that you managed well the situation and safely landed the plane.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So here is my question:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At the moment of the emergency you weren't able to explain with details everything that happened to the ATC.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;According to FAA, is it required to detail/explain (maybe file some kind of official document) your emergency to some kind of authority?&lt;/li&gt;&#xA;&lt;li&gt;If you do have to file an explanation, what information do you have to supply?&lt;/li&gt;&#xA;&lt;li&gt;Also what would happen if they &quot;didn't believe&quot; that situation was an emergency?&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="1700" LastEditorUserId="62" LastEditDate="2016-06-08T14:52:23.550" LastActivityDate="2016-06-20T14:41:08.077" Title="Do you have to explain what your emergency is?" Tags="&lt;faa-regulations&gt;&lt;emergency&gt;" AnswerCount="6" CommentCount="1" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29116" PostTypeId="1" AcceptedAnswerId="29138" CreationDate="2016-06-08T14:40:22.357" Score="11" ViewCount="4423" Body="&lt;p&gt;Why does every kind of propeller-powered plane lack an auto-throttle? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;No single-props no twin-props, not even turboprops like the Dash-8 Q400. To be honest, I don't know many turboprops, but if the Dash-8 doesn't have one, why shouldn't others? I mean, even a mini Cherokee 180 has an autopilot, whats so hard implementing an auto-throttle? And the Dash-8 is an airliner... without auto-throttle!&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks for your answers, I would really appreciate your answers.&lt;/p&gt;&#xA;" OwnerUserId="12629" LastEditorUserId="12623" LastEditDate="2016-06-08T15:12:03.263" LastActivityDate="2019-10-04T21:13:02.987" Title="Why do most propeller-powered planes not have an autothrottle?" Tags="&lt;propeller&gt;&lt;autothrust&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29117" PostTypeId="2" ParentId="29115" CreationDate="2016-06-08T14:41:28.450" Score="42" Body="&lt;p&gt;The order is &quot;Aviate, Navigate, Communicate&quot;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a pilot, your first responsibility is to keep the plane flying. After that it is to avoid hitting something or to avoid getting lost. After that comes communication. There are many instances of in-flight emergencies where the pilots never talked to anybody about it, because they were busy flying the plane...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;According to FAA, is it required to detail/explain (maybe file some kind of official document) your emergency to some kind of authority?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The FAA has many procedures on reporting accidents, incidents, and emergencies. Whether or not you report it depends on what the emergency was. If its a very sick passenger, there may be no reporting required. If your control cables failed, you are required to report it. I'll update this answer with the regulations as soon as I find them all. Quick answer is any time you declare an emergency or &quot;PAN-PAN&quot;, call the FSDO and let them know. Also depending on the nature of the accident/incident, you may be required to &lt;strong&gt;immediately&lt;/strong&gt; notify the NTSB. See &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=49:7.1.4.1.12.2.1.1&quot;&gt;CFR 49 830.5&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;If you do have to file an explanation, what information do you have to supply?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;This depends again on the nature of the emergency, and the FSDO/NTSB will ask you for the proper information when you file the report. At the very least they are probably going to want a narrative of what happened, and depending on what took place, you may want to contact your lawyer first. (Note: You may have to contact the NTSB &lt;em&gt;immediately&lt;/em&gt; but it doesn't say you need to provide details, just that there was an incident, so the NTSB would be your first call &quot;I had an incident&quot;, short and sweet, and the lawyer second.)&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Also what would happen if they &quot;didn't believe&quot; that situation was an emergency?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Its not ATC's responsibility to determine if you are lying or not. When you as a pilot say &quot;emergency&quot; you have their full attention. After you get on the ground and the emergency turns out to be you forgot to call your girlfriend/wife and wanted to get ahead of other traffic, then the FAA will get involved. Until you are on the ground, an emergency is handled as priority, regardless of the reason.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.nytimes.com/2011/04/06/nyregion/06plane.html?_r=0&quot;&gt;Here you can read a good story about a stupid pilot&lt;/a&gt; who abused the &quot;emergency&quot; system by landing on a public beach in New York because of an airsick passenger and an engine that was &quot;running a teensy bit rough&quot;. He didn't officially declare an emergency, and I can't find any record of official enforcement action against him for doing that. Note the NTSB did not investigate this &quot;incident&quot;.&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-06-08T15:04:58.113" LastActivityDate="2016-06-08T15:04:58.113" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29118" PostTypeId="2" ParentId="29106" CreationDate="2016-06-08T14:41:29.157" Score="5" Body="&lt;p&gt;The design philosophy of the F-117 was different from that of the F-22 (or F-18, which was not intended to be a stealth aircraft). The main design driver of the F-117 (in fact, practically the only one) was to reduce the RCS- the result being a distinctly non-aerodynamic design. The inclusion of separate horizontal stabilizers would've reduced the effectiveness of the design. The F-117 utilized the four elevons (a combination of ailerons and elevators) in lieu of the horizontal stabilizer, due to their location far back in the fuselage. No horizontal stabilizers were ever considered in the development of F-117.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The F-22, on the other had was a supersonic, high performance combat aircraft, which would require horizontal stabilizers for maneuverability (it is a super-maneuverable fighter which uses thrust vectoring). In absence of horizontal stabilizer, it would be very difficult for the F-22 or F-18 to reach their performance objectives, particularly for the carrier borne F-18.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In fact, there was a variant of F-117 which was designed to have a horizontal stabilizer- the unbuilt A/F-117X, which was expected to be a multi-mission aircraft (unlike F-117, which could barely do anything other than lob bombs). One main reason this design had a horizontal stabilizer was that the F-117 had quite high approach speeds, as the elevons didn't double up as flaps. The revised tail had horizontal stabilizers similar to F-22, which was used to reduce the descent rate and control the approach angle, which wouldn't have been possible with the original F-117. &lt;/p&gt;&#xA;" OwnerUserId="9731" LastEditorUserId="5517" LastEditDate="2016-06-08T15:25:56.413" LastActivityDate="2016-06-08T15:25:56.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29119" PostTypeId="2" ParentId="29115" CreationDate="2016-06-08T14:41:43.073" Score="8" Body="&lt;p&gt;Here in the US under the FAA if you say something to the extent of &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N12543 Declaring an Emergency &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;You have declared an emergency, no further explanation is necessary while you are in the air, they will always trust you and you will have priority over all other aircraft. Since you are now an aircraft under duress you can ask things of the controller that you may not otherwise be able to ask like &quot;please clear RW24 for a straight in approach&quot; or &quot;where is the nearest airfield and can you clear the runway&quot; etc. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Often times in declaring an emergency its in your best interest to provide a brief description to the controller for your own safety. For example if you say &lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;N12543 Fire in the Cockpit where is the nearest airfield?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;They will dispatch a fire crew (if available) or any similar situation that may require emergency services. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now you are on the ground safely, there is some stuff you need to do. You should contact your local &lt;a href=&quot;http://www.faa.gov/about/office_org/field_offices/fsdo/&quot; rel=&quot;nofollow&quot;&gt;FSDO to report the accident&lt;/a&gt; then you must file a report with the FAA/NTSB you can find the &lt;a href=&quot;http://www.ntsb.gov/pages/report.aspx&quot; rel=&quot;nofollow&quot;&gt;instructions on how to do this here&lt;/a&gt;. The full form &lt;a href=&quot;http://www.ntsb.gov/Documents/6120_1web_Reader.pdf&quot; rel=&quot;nofollow&quot;&gt;can be found here&lt;/a&gt; and is fairly verbose (it outlines what you need to report/the kind of explanation you need to give). Once this has been done the NTSB will investigate the incident which depending on the nature of the incident can take time. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I was always taught in flight school to err on the side of caution when it came to declaring. That falls in the &quot;better safe than sorry&quot; mind set. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="5517" LastEditDate="2016-06-20T14:41:08.077" LastActivityDate="2016-06-20T14:41:08.077" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29120" PostTypeId="1" CreationDate="2016-06-08T14:43:02.970" Score="19" ViewCount="41705" Body="&lt;p&gt;I would like to know the fundamental difference between GPS, GNSS and RNAV. How are they related each other? Are all/some of them synonyms? &lt;/p&gt;&#xA;" OwnerUserId="14891" LastEditorUserId="62" LastEditDate="2016-06-08T14:53:06.337" LastActivityDate="2017-09-26T04:22:15.357" Title="What is the difference between GPS, GNSS and RNAV?" Tags="&lt;terminology&gt;&lt;gnss&gt;" AnswerCount="3" CommentCount="0" FavoriteCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="29121" PostTypeId="2" ParentId="29120" CreationDate="2016-06-08T14:51:38.843" Score="5" Body="&lt;p&gt;Are you asking about the acronyms on their own or in relation to instrument approaches? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Generally speaking, &lt;a href=&quot;https://en.wikipedia.org/wiki/Global_Positioning_System&quot; rel=&quot;nofollow&quot;&gt;GPS stands for Global Positioning System&lt;/a&gt; and is a satellite based navigation system built and maintained by the US government.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GNSS stands for &lt;a href=&quot;https://en.wikipedia.org/wiki/GNSS_applications&quot; rel=&quot;nofollow&quot;&gt;Global Navigation Satellite System&lt;/a&gt;, which encompasses &lt;a href=&quot;https://en.wikipedia.org/wiki/Global_Positioning_System&quot; rel=&quot;nofollow&quot;&gt;GPS&lt;/a&gt; as well as the &lt;a href=&quot;https://en.wikipedia.org/wiki/GLONASS&quot; rel=&quot;nofollow&quot;&gt;Russian built and operated GLONASS&lt;/a&gt; (Global'naya Navigatsionnaya Sputnikovaya Sistema/&quot;&lt;em&gt;Global Navigation Satellite System&quot;&lt;/em&gt; in Russian) and Galileo (EU) or Beidou (China).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;RNAV stands for &lt;a href=&quot;https://en.wikipedia.org/wiki/Area_navigation&quot; rel=&quot;nofollow&quot;&gt;Area Navigation&lt;/a&gt; and is one of the main components of the US National Airspace System.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these things are forms of navigation used by aircraft and sometimes boats too. &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="3677" LastEditDate="2016-06-09T13:26:10.813" LastActivityDate="2016-06-09T13:26:10.813" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29122" PostTypeId="2" ParentId="29115" CreationDate="2016-06-08T14:51:40.403" Score="12" Body="&lt;p&gt;Per &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?node=14:2.0.1.3.10#se14.2.91_13&quot; rel=&quot;nofollow&quot;&gt;14 CFR 91.3&lt;/a&gt;, you only have to provide more details if the FAA asks for them:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§91.3   Responsibility and authority of the pilot in command.&lt;/strong&gt;&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;[...]&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(b) In an in-flight emergency requiring immediate action, the pilot in&#xA;  command may deviate from any rule of this part to the extent required&#xA;  to meet that emergency.  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(c) Each pilot in command who deviates from a rule under paragraph (b)&#xA;  of this section shall, upon the request of the Administrator, send a&#xA;  written report of that deviation to the Administrator.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;But &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?rgn=div8&amp;amp;node=49:7.1.4.1.12.2.1.1&quot; rel=&quot;nofollow&quot;&gt;per 49 CFR 830.5&lt;/a&gt; you have to notify the NTSB immediately (instructions &lt;a href=&quot;http://www.ntsb.gov/pages/report.aspx&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;) if various specific incidents occur:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;§830.5   Immediate notification.&lt;/strong&gt;  &lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;The operator of any civil aircraft,&#xA;  or any public aircraft not operated by the Armed Forces or an&#xA;  intelligence agency of the United States, or any foreign aircraft&#xA;  shall immediately, and by the most expeditious means available, notify&#xA;  the nearest National Transportation Safety Board (NTSB) office when:&lt;/p&gt;&#xA;  &#xA;  &lt;p&gt;(a) An aircraft accident or any of the following listed serious&#xA;  incidents occur: [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Engine failure in a large multi-engine aircraft is only reportable if two or more engines fail.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the general aviation world, if there's no damage to people or property then incidents or accidents rarely lead to any action from the FAA and they mostly aren't reported to the NTSB (because they don't have to be). Filing &lt;a href=&quot;http://asrs.arc.nasa.gov/report/electronic.html&quot; rel=&quot;nofollow&quot;&gt;an ASRS report&lt;/a&gt; is often a good idea, especially if the FAA does decide to investigate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have no idea about the airline world, but it's safe to say that any incident is taken a lot more seriously and handled a lot more formally, even minor ones. Although all in-flight emergencies are handled in the same way by ATC, whether they're airline flights or not.&lt;/p&gt;&#xA;" OwnerUserId="62" LastEditorUserId="62" LastEditDate="2016-06-08T19:40:00.507" LastActivityDate="2016-06-08T19:40:00.507" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29123" PostTypeId="2" ParentId="29115" CreationDate="2016-06-08T15:02:15.053" Score="11" Body="&lt;p&gt;My understanding in the US is that controllers will frequently consider an emergency that is handled well and has a successful outcome as a non-event.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Among the reasons:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Less paperwork for the Pilot&lt;/li&gt;&#xA;&lt;li&gt;Less review of the controllers work!&lt;br&gt;&#xA;&lt;em&gt;(Once the emergency is reviewed, the smallest mistake in phraseology can come up)&lt;/em&gt;&lt;/li&gt;&#xA;&lt;li&gt;It encourages people to fly safe by letting them declare an emergency without any consequences.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I've personally seen a pilot declare an emergency because:&lt;br&gt;&lt;em&gt;&quot;One cylinder is running a little hotter than the others&quot;&lt;/em&gt;.&lt;br&gt;   He landed just fine, and didn't have to file anything.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Its better to declare an emergency and get extra attention in case the situation gets worse than it is to avoid declaring just because you're afraid of paperwork, and end up dead.&lt;/p&gt;&#xA;" OwnerUserId="43" LastActivityDate="2016-06-08T15:02:15.053" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29124" PostTypeId="2" ParentId="29106" CreationDate="2016-06-08T15:08:42.027" Score="8" Body="&lt;p&gt;They're very different aircraft, built to different requirements, meant to fill very different roles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Large tails are good for pitch authority and high-alpha---which are good for maneuvering and dogfighting, but not very relevant to the F-117's missions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The F-117&lt;/strong&gt; was a medium-altitude, &lt;strong&gt;tactical bomber&lt;/strong&gt; that spent its life trucking around a pair of large, 2000 lb bombs. It wasn't expected to tango with opposing fighters, so maneuverability was less important, thus the small tail and very modest T/W ratio. &lt;em&gt;Stealth&lt;/em&gt; kept it alive, not fancy footwork. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Hornet&lt;/strong&gt; classic (and Super Hornet thereafter) is a &lt;strong&gt;multirole fighter&lt;/strong&gt;, expected to perform everything from fleet defense, SEAD, interdiction, recon, and of course CAS. It was made to handle extremely well at low-speed and high AOA. Pitch-rate and nose-pointing is very good---it will easily turn inside an F-16, albeit briefly (turn rate v. turn radius). Low-speed controllability is also crucial for landing on carriers. This is why it needs large tails&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;The Raptor&lt;/strong&gt; is an &lt;strong&gt;air superiority fighter&lt;/strong&gt; (with some multirole capability). Its job is going toe-to-toe with anyone else in the air. So all the classic performance parameters matter: T/W, acceleration, top speed, climb rate, turn rate &lt;em&gt;and&lt;/em&gt; turn radius. It will out-turn a Hornet (instantaneous and sustained) and out-run an F-16 despite being twice as heavy as either. Large tails are even more important for control here, especially the very high altitudes at which the F-22 can fly.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In other words, the Raptor and Hornet need to be pretty nimble---the F-117 does not.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Here's a Super Hornet giving a little show. Watch it yank its nose around at 4:35 and 5:00.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;div class=&quot;youtube-embed&quot;&gt;&lt;div&gt;&#xD;&#xA;                &lt;iframe width=&quot;640px&quot; height=&quot;395px&quot; src=&quot;https://www.youtube.com/embed/fDfVwTQ-RhE?start=0&quot;&gt;&lt;/iframe&gt;&#xD;&#xA;            &lt;/div&gt;&lt;/div&gt;&lt;/p&gt;&#xA;" OwnerUserId="7394" LastEditorUserId="7394" LastEditDate="2016-06-08T18:04:58.447" LastActivityDate="2016-06-08T18:04:58.447" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29126" PostTypeId="2" ParentId="29053" CreationDate="2016-06-08T16:25:27.560" Score="7" Body="&lt;p&gt;Alright so here is the outcome: &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I called FSDO, spoke with a real nice guy who told me to give him a call if I couldn't handle this online.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Called a zillion bureaucracies, all telling me to call someone else.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Called the nice guy at FSDO, set up an appointment for a name &lt;strong&gt;correction&lt;/strong&gt; not a name change. Went to the appointment and was in and out in under an hour.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're having the same issue, I would recommend bringing every official identification you've got: passport, birth certificate, drivers license, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Tl;DR&lt;/strong&gt; call FSDO and tell them you need a name &lt;strong&gt;correction&lt;/strong&gt;. NOT a name change. Can't stress that enough.&lt;/p&gt;&#xA;" OwnerUserId="267" LastActivityDate="2016-06-08T16:25:27.560" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29127" PostTypeId="1" CreationDate="2016-06-08T17:37:19.330" Score="10" ViewCount="2867" Body="&lt;p&gt;What environmental factors are considered when a new runway construction is planned (e.g. winds, weather, sun direction, etc.)?&lt;/p&gt;&#xA;" OwnerUserId="770" LastEditorUserId="14897" LastEditDate="2017-05-03T19:46:31.890" LastActivityDate="2019-01-20T14:20:33.190" Title="What factors are considered when a runway is planned?" Tags="&lt;runways&gt;&lt;airport-design&gt;" AnswerCount="2" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29128" PostTypeId="2" ParentId="29120" CreationDate="2016-06-08T17:46:40.070" Score="2" Body="&lt;p&gt;Global Positioning System (GPS) is a U.S. initiated, monitored and maintained system.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As Dave pointed out, GLONASS is maintained by Russia, Galileo by Europe and BeiDou by China.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;All of these systems and others comprise the Global Navigation Satellite System (GNSS).  There is a subset of GNSS called satellite based augmentation system (SBAS).  Under this subset is the U.S. wide area augmentation system (WAAS), EGNOS by Europe, MSAS by Japan and GAGAN by India.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&quot;Random&quot; Area Navigation (RNAV) allows an aircraft to choose any course within a network of ground based stations or GNSS.  It is typically developed and flight checked (in the U.S.) and published as procedures.  In the U.S. you will see approaches titled &lt;code&gt;RNAV (GPS)...&lt;/code&gt; that use procedures developed by the FAA.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="9491" LastEditDate="2017-09-26T04:22:15.357" LastActivityDate="2017-09-26T04:22:15.357" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29129" PostTypeId="1" AcceptedAnswerId="29132" CreationDate="2016-06-08T17:53:46.693" Score="11" ViewCount="8418" Body="&lt;p&gt;I've wondered this for a long time (every six months while getting my latest first class medical), but what are the doctors checking for when they perform the urine test?  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Maybe Drugs?  Medical conditions (which ones)?  Both?  Other things?&lt;/p&gt;&#xA;" OwnerUserId="69" LastActivityDate="2016-06-08T18:17:24.200" Title="Why is a urine test performed during pilot medical examinations?" Tags="&lt;faa-regulations&gt;&lt;medical&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29130" PostTypeId="2" ParentId="27944" CreationDate="2016-06-08T18:01:25.743" Score="2" Body="&lt;p&gt;The owner could do regular checks of the aircraft's Hobbs meter, and if the times don't match what the log is saying, then there could be some red flags being thrown.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If someone it out to deceive, I'm sure they could get around this, but maybe then, the problem is giving access of expensive equipment to people who aren't trustworthy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are GPS tracking systems that could keep a movement log in memory.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastActivityDate="2016-06-08T18:01:25.743" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29131" PostTypeId="2" ParentId="29120" CreationDate="2016-06-08T18:08:06.103" Score="19" Body="&lt;p&gt;As stated in the othe answers, &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;strong&gt;GPS&lt;/strong&gt; is the US Global Positioning System&lt;/li&gt;&#xA;&lt;li&gt;&lt;strong&gt;GNSS&lt;/strong&gt; is an umbrella term that encompasses GPS as well as other nations' satellite systems that achieve essentially the same capability&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;RNAV&lt;/strong&gt; is the aircraft capability that allows you to navigate from point to point, defined by Latitude/Longitude and independent of any ground-based system.  There are various ways that the hardware in the aircraft maintains its position.  It may use GPS sensors, it may use GLONASS, it may uses a combination of satellite systems, it may use DME/DME updates from ground-based navaids.  But the point of RNAV is that &lt;em&gt;for the most part&lt;/em&gt; the procedures are agnostic with regard to how the position info is obtained.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, you can have RNAV routes and approaches, meaning that the airway or approach segments are defined by Lat/Lon waypoints, and as long as your system meets defined accuracy tolerances (usually 1.0 NM enroute and 0.3 NM for an approach in the US), you can fly that airway or approach.  There are more stringent tolerances incorporated into RNAV(RNP) approaches, and these require that the system can monitor its accuracy and alert the pilot if the system isn't confident that its position is accurate to within a specified performance.  This can be set to match whatever is required on the approach; 0.1 NM is common, although there are other values that can be specified.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the US, the FAA typically distinguishes basic RNAV approaches by designating them &lt;strong&gt;RNAV(GPS)&lt;/strong&gt; in the title, as opposed to &lt;strong&gt;RNAV(RNP)&lt;/strong&gt;.  (The RNAV(RNP) approaches require a couple of additional things beyond basic RNAV, but those are beyond the scope of this question.)  Internationally, &quot;RNAV(GNSS)&quot; is often used instead of &quot;RNAV(GPS)&quot; in the approach title, but functionally they're pretty well the same thing -- it's simply a nod internationally to the fact that if your FMC knows where it is, the approach designer doesn't care which satellite system it's getting its position data from.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the &quot;old days&quot;, it was possible to have RNAV operations that worked by taking radial/DME data from a single VOR and creating a pseudo-VOR essentially whereever you wanted, and the HSI or other display would act as if the VOR were in the new location.  This was very early RNAV capability, in that it allowed you to fly a straight line course by keeping the HSI centered rather than flying VOR to VOR.  These days, that capability is pretty much gone, in favor of the much greater capability of GPS.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastEditorUserId="7532" LastEditDate="2016-06-09T04:06:55.397" LastActivityDate="2016-06-09T04:06:55.397" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29132" PostTypeId="2" ParentId="29129" CreationDate="2016-06-08T18:17:24.200" Score="8" Body="&lt;p&gt;It's for diabetes and kidney disease. You can read the AME guidance &lt;a href=&quot;https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item57/&quot;&gt;here&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Item 57. Urine Test&lt;/strong&gt;&lt;br&gt;&#xA;  Glycosuria or proteinuria is cause for deferral of medical&#xA;  certificate issuance until additional studies determine the status of&#xA;  the endocrine and/or urinary systems. If the glycosuria has been&#xA;  determined not to be due to carbohydrate intolerance, the Examiner may&#xA;  issue the certificate. Trace or 1+ proteinuria in the absence of a&#xA;  history of renal disease is not cause for denial.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Glycosuria&quot;&gt;Glycosuria&lt;/a&gt; is an indication of diabetes, and &lt;a href=&quot;https://en.wikipedia.org/wiki/Proteinuria#Conditions_with_proteinuria_as_a_sign&quot;&gt;proteinuria&lt;/a&gt; is an indication of kidney disease (among dozens of other things, if Wikipedia is to be believed). And the AME can do other tests too, if he thinks they're necessary:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;The Examiner may request additional urinary tests when they are&#xA;  indicated by history or examination.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;The regulatory reference (per the AME guide) is &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&amp;amp;sid=b0859a44f58f555dbdc7660c19c131c6&amp;amp;rgn=div8&amp;amp;view=text&amp;amp;node=14:2.0.1.1.5.2.1.7&amp;amp;idno=14&quot;&gt;14 CFR 67.113&lt;/a&gt; for a first-class medical, but exactly the same regulation is there for second- and third-class too.&lt;/p&gt;&#xA;" OwnerUserId="62" LastActivityDate="2016-06-08T18:17:24.200" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29133" PostTypeId="2" ParentId="29116" CreationDate="2016-06-08T18:29:38.493" Score="0" Body="&lt;p&gt;Autothrottles are a wonderful piece of automation to have, but they are expensive to install and maintain, and the technology behind them is complicated and can be easily misunderstood by a pilot who isn't fully up-to-speed with the automation and &quot;what's it doing now.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An autopilot is pretty easy to grasp, conceptually.  Turn on altitude hold, it does.  Turn on heading hold, it does.  Couple the autopilot to a VOR or GPS course, and it holds that.  There's no energy management, no interactions between the left/right and the airspeed.  Navigating vertically changes that, because you have a lot of coupling between the vertical modes (i.e. things driving the elevator) and the throttle modes (i.e. things driving the throttle).  This translates into more complicated software, more controls, and more required pilot understanding of what's going on in the FMC and autopilot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Beyond this, when you have an autothrottle, you need to make sure that it will disengage fully when you tell it to, that it can be overridden with pilot input, and that it won't drive the engine into an out-of-limits condition (RPM, Manifold Pressure, Torque, EGT, etc).  Jet engines are generally pretty simple in this regard (particularly when they're already protected with a FADEC) compared to turboprop or (especially) reciprocating engines.  Do you really want your autothrottle trying to lean out the engine in the climb?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The end result of all of this is the the economics tend not to be worth it to put autothrottles in the various prop-driven aircraft.&lt;/p&gt;&#xA;" OwnerUserId="7532" LastActivityDate="2016-06-08T18:29:38.493" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29138" PostTypeId="2" ParentId="29116" CreationDate="2016-06-08T19:50:54.880" Score="6" Body="&lt;p&gt;&lt;strong&gt;Because each jet engine only has one lever; each piston engine has three.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;p&gt;Jet engine's throttle is pretty straight forward - move forward, more power. The computer automatically manages fuel flow to prevent surge, flameout and N1 overshoot.&lt;/p&gt;&#xA;&lt;p&gt;On a piston engine you have three - a mixture lever, a propeller lever and a throttle lever. Granted, I don't think auto-mixture would be too hard to implement. Now, do I want a high-speed climb or high-power climb? And remember, the prop and throttle must be managed together. You cannot go beyond a certain power range with the props set for low rpm, otherwise you'll damage the engine.&lt;/p&gt;&#xA;&lt;p&gt;It's like a car's automatic transmission, except it has one more dimension.&lt;/p&gt;&#xA;&lt;h2&gt;Power affects pitch&lt;/h2&gt;&#xA;&lt;p&gt;When you change power you must change the aircraft's pitch altogether. Autopilots on modern airlines have quite a number of vertical modes: ALT, V/S, G/S, VNAV, FLCH, TO/GA, CLB etc. None of those have the concept of gear ratio, which is required for propeller management.&lt;/p&gt;&#xA;&lt;p&gt;Can you design an autopilot system such that it functions on propeller engines? Absolutely. But it is going to be complicated. Not only the usual operations, but the failure modes, have to be engineered and learnt by the pilots. How do you deal with an auto-mixture failure? RPM mismatch? Such training would add unnecessary cost to an otherwise simple aircraft operation. If your airplane does not have a variable pitch propeller, it is probably too simplistic for this kind of autopilot anyway.&lt;/p&gt;&#xA;&lt;p&gt;Jets have another property which makes auto throttle a logical choice - the faster you fly, the more powerful the engines. Thus, on a jet, you would have to make continuous throttle adjustment if you change your airspeed. So an auto throttle would be helpful. Pistons do not behave like that.&lt;/p&gt;&#xA;&lt;h2&gt;Turboprops&lt;/h2&gt;&#xA;&lt;p&gt;One of the main reasons for choosing piston aircraft is - it is simple. It just fly. No fancy stuff. No lengthy preflight checks. No computers. I just want to get flying. This thinking also extends to turboprops.&lt;/p&gt;&#xA;&lt;p&gt;It's worthy to note that the ATR does not have auto throttle as well. The ATR 42 has power management (but not speed management), where activating it will simply move a bug on the torque gauge; the pilots have to manually move the levers to follow it. The ATR 72 has a notch for the pilots to place the throttle levers, but still, no motor to move the levers automatically. I can't think of any reason behind this design philosophy besides simplicity and cost.&lt;/p&gt;&#xA;" OwnerUserId="3386" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2016-06-08T20:17:22.070" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29139" PostTypeId="2" ParentId="2883" CreationDate="2016-06-08T21:58:27.573" Score="26" Body="&lt;p&gt;&lt;em&gt;Do airplanes need wings?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Wait a minute! Airplanes &lt;strong&gt;have to&lt;/strong&gt; have wings by FAA regulation, so you won't find any airplane without wings in the US.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;http://www.faa.gov/air_traffic/flight_info/avn/maintenanceoperations/programstandards/webbasedtraining/CBIChg29/AVN300WEB/Glossarytems.htm&quot; rel=&quot;noreferrer&quot;&gt;FAA definition&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Airplane&lt;/strong&gt;. An engine-driven fixed-wing aircraft heavier than air, that&#xA;  is supported in flight by the dynamic reaction of the air against its&#xA;  wings.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;My advice here: If you encounter an airplane without wings (an unapproved case) do only your duty, call FAA immediately at 866-TELL-FAA (866-835-5322):&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/gnJrp.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/gnJrp.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;(&lt;a href=&quot;http://www.bbc.com/news/world-australia-29876001&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;BR&gt;&#xA;Aircraft on the other hand has benefited from FAA's leniency, and don't have to have wings:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Aircraft&lt;/strong&gt;. A device that is used or intended to be used for flight in&#xA;  the air.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;As you can see, they are not required to have an engine, nor large rocks in the cargo hold to ensure they are still heavier than air. No, the only requirements for an aircraft are that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;At the beginning you intend to make the thing fly. It's perfectly legal to try to see if you could save wings from the bill, as long as you are honestly expecting it to fly.&lt;/li&gt;&#xA;&lt;li&gt;You want it to fly in the air, not in the water, certainly not in the vacuum of the space. That's the part requiring all your attention during the design. The lift must be carefully monitored, you need to remain in this tiny layer called &lt;em&gt;atmosphere&lt;/em&gt;, else you leave the aircraft category, and maybe the aviation field too.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;This is a wingless aircraft:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CaaNW.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CaaNW.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;Full scale Lippisch's Aerodyne, a VTOL aircraft built at Collins (&lt;a href=&quot;http://ideacape.blogspot.fr/2015/08/a-collection-of-some-of-most-bizarre.html&quot; rel=&quot;noreferrer&quot;&gt;Source&lt;/a&gt;)&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This one is fully in the law, don't call FAA...&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;It's certainly a stupid answer, I did my best for, but it's correct :-)&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-06-11T20:48:25.750" LastActivityDate="2016-06-11T20:48:25.750" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29140" PostTypeId="2" ParentId="29106" CreationDate="2016-06-08T22:02:11.317" Score="9" Body="&lt;p&gt;The rudders on modern fighters are canted mostly to &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0157.shtml&quot; rel=&quot;noreferrer&quot;&gt;reduce their radar cross section&lt;/a&gt;. A straight vertical tail would produce a corner reflector in combination with the fuselage or the wing and would send radar waves straight back to their source. To reduce the detection radius, such a behavior must be avoided. The first aircraft to use this trick was the SR-71.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On the F-18 an additional reason was to move the tips of the vertical tails into the lateral position of the chine vortex: The wing's big leading edge extension produces a strong vortex at high angle of attack which improves the effectiveness of the tails and gives better yaw control. However, the bursting of the vortex would cause heavy buffeting, and an &lt;a href=&quot;http://www.aerospaceweb.org/question/planes/q0176.shtml&quot; rel=&quot;noreferrer&quot;&gt;additional fix was needed&lt;/a&gt; to improve the fatigue life of the tails.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The horizontal tail is a necessity for pitch control and to trim the flap moments in the landing configuration. Just look at &lt;a href=&quot;https://en.wikipedia.org/wiki/Boeing_X-32&quot; rel=&quot;noreferrer&quot;&gt;Boeing's entry to the JSF competition&lt;/a&gt;: The X-32 was initially planned as a delta with only vertical tails, but when the Navy refined their carrier operation requirements, Boeing had to add a conventional horizontal tail to achieve the required angle of attack and minimum speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/aT7Be.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/aT7Be.png&quot; alt=&quot;Boeing X-32 (left), planned production version (right)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Boeing X-32 (left, &lt;a href=&quot;http://avia-museum.narod.ru/usa/boeing_xf-32-2.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) and the planned production version (right, &lt;a href=&quot;http://www.deagel.com/library1/medium/2007/m02007012800028.jpg&quot; rel=&quot;noreferrer&quot;&gt;source&lt;/a&gt;) with the added horizontal tail. The F-117 was an Air Force plane with very limited agility, so it could get away with a tailless design. Real fighters and carrier airplanes cannot.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Giving the horizontal tail dihedral reduces its effectiveness in two ways: &lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Angle of attack changes from pitch variations are reduced by the cosine of the dihedral angle, and &lt;/li&gt;&#xA;&lt;li&gt;the vertical component of the aerodynamic force is also reduced by the cosine of the dihedral angle.&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Note that the drag of a &lt;a href=&quot;https://aviation.stackexchange.com/questions/9504/what-is-the-difference-between-the-v-shape-tail-and-the-straight-tail-on-the-bee/9509#9509&quot;&gt;V-tail&lt;/a&gt; depends on the total lift created, regardless of its direction. Only the horizontal component is effective for pitch control, so a steeply angled V-tail is very ineffective for pitch control. In air combat the high drag will reduce performance when it is needed most. &lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-06-08T22:09:22.860" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29143" PostTypeId="1" CreationDate="2016-06-09T00:10:13.977" Score="8" ViewCount="313" Body="&lt;p&gt;The development of computer flight systems is characterised by lengthy certification processes, exceptionally rigorous testing regimes and a default position of extreme caution.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A change in any component at any layer in the hardware/software stack could introduce new incorrect behaviour. For example, microprocessors are so complex that &lt;a href=&quot;https://en.wikipedia.org/wiki/Motorola_68040#68LC040&quot; rel=&quot;nofollow noreferrer&quot;&gt;different manufacturing revisions of the same model can introduce bugs&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a result, these systems are very tightly specified at all levels and very slow to change, so that many systems still in production use what in most other contexts would be considered obsolete technology.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;CPUs such as the 68040 and 80486 (both introduced around 1990) were designed into systems a quarter of a century ago that are still being produced today.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Summary of the problem&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The pace of development of the electronics industry has accelerated hugely since the first generation of computerised flight control systems were introduced in the early 1970s, and is becoming increasingly incompatible with the needs of the aviation industry. It means that for example:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Devices now have manufacturing lifetimes of just a few years (compared with several times that a few decades ago).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Devices are now intended to have much shorter service lives than they used to (by orders of magnitude).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Increasingly tiny widths in microprocessors mean they succumb increasingly early to problems such as oxide breakdown.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Aerospace represents a very small portion of the manufacturers' business: their main customers make consumer devices, and have utterly different demands on the electronics industry from those of customers in aviation.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Research into the issue&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;These and other issues are outlined in some detail in &lt;a href=&quot;https://nepp.nasa.gov/files/16365/08_102_4_%20JPL_White.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;Microelectronics Reliability: Physics-of-Failure Based Modeling and Lifetime Evaluation&lt;/a&gt; (and no doubt elsewhere - this was just one I found while trying to answer my own question).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;http://avsi.aero&quot; rel=&quot;nofollow noreferrer&quot;&gt;Aerospace Vehicle Systems Institute&lt;/a&gt; (AVSI) Consortium Project #17 &lt;a href=&quot;http://avsi.aero/projects/current-projects/avionics-reliability/semiconductor-reliability/815-2/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Methods to Account for Accelerated Semiconductor Device Wear Out&lt;/a&gt; has attempted to quantify these risks. &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The question&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;What can the aerospace industry do - or what is it already doing - to mitigate the problems and risks this poses?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="14197" LastEditDate="2019-04-19T07:00:07.120" LastActivityDate="2019-04-19T20:54:21.410" Title="What measures can the aerospace industry take to deal with changes in the electronic industry that are incompatible with its own conservatism?" Tags="&lt;avionics&gt;&lt;electronics&gt;" AnswerCount="2" CommentCount="11" ClosedDate="2019-04-20T19:59:44.803" ContentLicense="CC BY-SA 4.0" />
  <row Id="29144" PostTypeId="2" ParentId="29127" CreationDate="2016-06-09T00:17:53.330" Score="14" Body="&lt;p&gt;First, &lt;a href=&quot;https://en.wikipedia.org/wiki/Wind_rose&quot; rel=&quot;noreferrer&quot;&gt;wind rose&lt;/a&gt; data, unless you built the airport in the early 20th century without weather data.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/ZQSWGm.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/ZQSWGm.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;BR&gt;By BREEZE Software (&lt;a href=&quot;http://www.breeze-software.com/&quot; rel=&quot;noreferrer&quot;&gt;http://www.breeze-software.com/&lt;/a&gt;) [&lt;a href=&quot;http://www.gnu.org/copyleft/fdl.html&quot; rel=&quot;noreferrer&quot;&gt;GFDL&lt;/a&gt; or &lt;a href=&quot;http://creativecommons.org/licenses/by-sa/3.0/&quot; rel=&quot;noreferrer&quot;&gt;CC-BY-SA-3.0&lt;/a&gt;], &lt;a href=&quot;https://commons.wikimedia.org/wiki/File%3AWind_rose_plot.jpg&quot; rel=&quot;noreferrer&quot;&gt;via Wikimedia Commons&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It's nice to check old airports and see how they evolved over time. In the past they usually built three runways, each separated by 60 degrees in direction, to cover the compass. Over time some are lengthened, others demolished, more are added in the favorable direction, and so on. Nice example is &lt;a href=&quot;https://en.wikipedia.org/wiki/O&amp;#39;Hare_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;KORD&lt;/a&gt; if you want to hunt the history on your own.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example of runway closure: &lt;a href=&quot;https://aviation.stackexchange.com/q/31432/14897&quot;&gt;Why did the north / south runways close at Daugherty Field (KLGB)?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a commercial airport expecting long haul jets, you need a long runway, to bring down civil works cost you need to find a place with a relatively flat terrain that would house said long runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Airport's elevation also plays a factor to runway length. The higher the airport, the longer the runways need to be. Surrounding terrain also is important. Unless you can build an island: &lt;a href=&quot;https://en.wikipedia.org/wiki/Hong_Kong_International_Airport&quot; rel=&quot;noreferrer&quot;&gt;VHHH&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For sun direction, engineers recommend Ray Bans, since the Earth spins.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/JU6R5m.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/JU6R5m.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2017-05-04T13:27:54.167" LastActivityDate="2017-05-04T13:27:54.167" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29146" PostTypeId="1" AcceptedAnswerId="29147" CreationDate="2016-06-09T03:04:35.730" Score="6" ViewCount="288" Body="&lt;p&gt;In kinda reverse of &lt;a href=&quot;https://aviation.stackexchange.com/questions/14535/did-flight-engineers-progress-to-be-pilots&quot;&gt;Did Flight Engineers progress to be pilots?&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In three-crew cockpit can a person qualified as pilot work in the position of flight engineer? Does a flight enginner have different qualifications that are not covered by an ATPL, thus rendering a pilot unqualified for the position?&lt;/p&gt;&#xA;" OwnerUserId="679" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:59.263" LastActivityDate="2016-06-10T10:49:49.093" Title="Can a pilot work flight engineer's station?" Tags="&lt;pilots&gt;&lt;crew&gt;" AnswerCount="1" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29147" PostTypeId="2" ParentId="29146" CreationDate="2016-06-09T03:51:04.247" Score="5" Body="&lt;p&gt;The pilot cannot just sit down in the flight engineer station.  First there is a different FAA flight engineer certificate that the pilot needs to obtain.  Secondly, the pilot would need to go through the airline's training program for that station.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Granted, a pilot who has flown that airplane before should quickly get those done.&lt;/p&gt;&#xA;" OwnerUserId="9491" LastEditorUserId="13197" LastEditDate="2016-06-10T10:49:49.093" LastActivityDate="2016-06-10T10:49:49.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29148" PostTypeId="1" AcceptedAnswerId="68315" CreationDate="2016-06-09T05:57:52.860" Score="7" ViewCount="1991" Body="&lt;p&gt;It is explained &lt;a href=&quot;http://www.aerospaceweb.org/question/dynamics/q0045.shtml&quot; rel=&quot;nofollow noreferrer&quot;&gt;here&lt;/a&gt; that adverse yaw is caused by the difference in induced drag due to the difference in lift being generated by each wing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I've also seen a couple of &lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw?wprov=sfsi1&quot; rel=&quot;nofollow noreferrer&quot;&gt;websites&lt;/a&gt; (including &lt;a href=&quot;https://en.wikipedia.org/wiki/Adverse_yaw?wprov=sfsi1&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;) that argue that this explanation is wrong. They explain the cause of adverse yaw as being the change in the &lt;em&gt;direction&lt;/em&gt; of the lift vector during a roll, or what some refer to as the &quot;twisted lift&quot; concept. They usually have a diagram like the following:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/qAInY.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/qAInY.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;&lt;a href=&quot;http://www.av8n.com/how/htm/yaw.html#sec-adverse-yaw&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The twisted lift explanation discounts a difference in induced drag due to a change in the &lt;em&gt;amount&lt;/em&gt; of lift. They contend that lift and drag remain the same but they twist in different directions. The descending wing has a slightly higher local AoA and the rising wing slightly lower. Since lift is perpendicular to the &lt;em&gt;local airflow&lt;/em&gt; the lift vector rocks forward on one wing and aftward on the other. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;This explanation seems flawed to me. &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;First of all, in the diagram they show the force on each wing being the same. If that were the case the aircraft wouldn't roll at all, it would ONLY yaw.&lt;/li&gt;&#xA;&lt;li&gt;Second, the vector of lift being perpendicular to the airflow is correct, but that is really just an arbitrary division of the total aerodynamic force. The yaw axis of the plane is not dependent on airflow. It would be dependent on the portion of the force vector parallel to the wing chord, aka the axial force. As shown in &lt;a href=&quot;https://aviation.stackexchange.com/q/28019/8730&quot;&gt;another question&lt;/a&gt;, depending on a number of factors the force vector in relationship to the wing does not necessarily move forward with an increase in AoA. &lt;/li&gt;&#xA;&lt;li&gt;I can't come up with solid numbers, but trying to figure this out for normal flight speeds it would require a very fast roll to even make a 1° difference in local AoA. I ran numbers for a 3° per sec roll at 120 KTAS on a 36ft wingspan (C172) and came up with a change in AoA of about .27°, and that Is only at the wingtip. It would decrease the closer it got to the fuselage. It doesn't seem like it would be enough to cause a significant change in vector and a resulting yaw moment. Or at least it would be secondary in magnitude to the difference in the drag due to reduction of lift. &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Since the changes in lift are being created either by changing the effective camber of the wings (ailerons) or by altering the trailing edge flow (spoilerons) rather than a change in AoA I don't think it's quite so simple to predict that the direction of the aerodynamic vectors will necessarily move in opposite directions as this theory assumes.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If this explanation is correct can someone show me what I'm missing?&lt;/p&gt;&#xA;" OwnerUserId="8730" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.023" LastActivityDate="2019-09-01T08:01:41.187" Title="Is this explanation of adverse yaw correct?" Tags="&lt;flight-controls&gt;&lt;flight-dynamics&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29149" PostTypeId="2" ParentId="29115" CreationDate="2016-06-09T07:03:00.787" Score="2" Body="&lt;p&gt;From my knowledge, all you have to do to declare an emergency is to announce it over the radio.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This gets you priority for the traffic controller responsible for your area. They may further ask you questions, to coordinate any emergency services that you may require, or to further help them in their duties guiding you.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For example, if you have a co-pilot incapacitated they may put further spacing between you and other aircraft in the sequence in order to give you more time to go through the landing checklists and procedures.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Or if you have a medical emergency they may ask in order to inform the airport to ready the emergency services; or if a mechanical issue they may coordinate with the airport for a full stop on the runway, etc.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However &lt;em&gt;all of that is strictly optional&lt;/em&gt;. As in an emergency situation your first priority is to fly the aircraft; therefore ATC will understand if you are not very chatty on the radio, etc.&lt;/p&gt;&#xA;" OwnerUserId="1049" LastActivityDate="2016-06-09T07:03:00.787" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29150" PostTypeId="1" AcceptedAnswerId="29152" CreationDate="2016-06-09T07:35:42.877" Score="4" ViewCount="1000" Body="&lt;p&gt;I'm working on a program that requires a taxiing passenger aircraft (of any model) to perform a semi-accurate turn given a steering angle of the front landing gear. For this I need to calculate the pivot/center point for the aircraft to rotate around. There seem to be a few factors that influence this (including some basic specifications of the aircraft) but I can't seem to find even a general equation that breaks it down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I'm aware that there are also a number of more complex factors that would influence this, but for my purposes I'm assuming an ideal situation with minimal interference.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thanks in advance!&lt;/p&gt;&#xA;" OwnerUserId="15326" LastActivityDate="2016-06-10T19:54:07.413" Title="Is there a formula for calculating the pivot point of an aircraft while turning on the ground?" Tags="&lt;landing-gear&gt;&lt;ground-operations&gt;&lt;taxiing&gt;" AnswerCount="2" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29151" PostTypeId="1" CreationDate="2016-06-09T07:36:23.713" Score="3" ViewCount="635" Body="&lt;p&gt;Is it possible to deploy the thrust reversal, in the cruise phase of a flight? And, if they are accidentally deployed, what could be the possible consequences? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As the cruise phase requires a lot of lift, so certainly the impact would not be very desirable.. &lt;/p&gt;&#xA;" OwnerUserId="8482" LastActivityDate="2016-06-09T08:08:15.827" Title="What would happen if thrust reversal is accidentally deployed during a flight?" Tags="&lt;thrust-reverser&gt;&lt;cruise&gt;" AnswerCount="1" CommentCount="0" FavoriteCount="0" ClosedDate="2016-06-09T11:43:13.963" ContentLicense="CC BY-SA 3.0" />
  <row Id="29152" PostTypeId="2" ParentId="29150" CreationDate="2016-06-09T07:50:25.957" Score="1" Body="&lt;p&gt;If you assume the main gear does not rotate (in the left-right sense), then the pivot point will always be somewhere on a line joining the two main gears.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You can then use trigonometry and the turn angle of the nose wheel to identify the centre of rotation. (Assume the nose tyre does not slip sideways.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;(By the way this is very similar to Ackermann steering used on cars - lots of standard mechanical texts talk about this.)&lt;/p&gt;&#xA;" OwnerUserId="8417" LastActivityDate="2016-06-09T07:50:25.957" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29153" PostTypeId="2" ParentId="29151" CreationDate="2016-06-09T08:08:15.827" Score="3" Body="&lt;p&gt;If the aircraft is at cruise altitude and speed, the wing will see a large loss of lift, and will become uncontrollable.&lt;br&gt;&#xA;It used to be possible to deploy thrust reversers in Boeings. It was not feared as a problem, since early tests showed that accidental deployments were survivable and the plane would stay controllable. However, these tests were only performed at low speeds, since low-speed deployments were assumed to be the most critical (&lt;a href=&quot;http://lessonslearned.faa.gov/ll_main.cfm?TabID=2&amp;amp;LLID=34&amp;amp;LLTypeID=2#null&quot; rel=&quot;nofollow&quot;&gt;source&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;But then in 1991 &lt;a href=&quot;http://en.wikipedia.org/wiki/Lauda_Air_Flight_004&quot; rel=&quot;nofollow&quot;&gt;Lauda Air 004&lt;/a&gt; crashed mid-flight in Thailand after an uncommanded thrust reverser deployment. After this crash, additional safety features such as mechanical positive locks were mandated to prevent thrust reverser deployment in flight.&lt;br&gt;&#xA;I'm not sure about Airbus, but I guess all current aircraft have some kind of lock.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Because engines on modern aircraft are so closely attached to the wing, the thrust reverser exhaust flow is right in front of the wing. Therefore, the wing will see a lower flow speed which results in a loss of lift.&lt;/p&gt;&#xA;" OwnerUserId="598" LastActivityDate="2016-06-09T08:08:15.827" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29154" PostTypeId="1" CreationDate="2016-06-09T08:20:03.093" Score="13" ViewCount="8143" Body="&lt;p&gt;I am not a pilot and have come to this site to ask a question about the measurement of height.  This is as a result of the comments made as a result of a question in the Physics Stack Exchange forum &lt;a href=&quot;https://physics.stackexchange.com/questions/261185/does-barometer-improve-gps-position-accuracy/261240#261240&quot;&gt;&quot;Does barometer improve gps accuracy?&quot;&lt;/a&gt;  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I feel that there will be more of you on this site who have real time experience with flying and so can answer my question which is:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Which is more accurate for height measurement: GPS or barometer?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have noted that those engaged in geocaching often have GPS units with built-in barometers to improve height accuracy.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of my friends who is a pilot responded as follows:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A light aircraft relies on a barometer that is set to the standard&#xA;  1013 millibars when in cruise at height (or the regional QNH when&#xA;  lower) but they set to the local reading for the airfield (QFE) when&#xA;  planning their decent. Commercial aircraft also have ground proximity&#xA;  radar but they also have a standard set of old fashioned flight&#xA;  instruments in case the electronics fail. My old aircraft GPS did&#xA;  indeed read out height as well but you were told never to rely on it!&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;" OwnerUserId="15334" LastEditorUserId="69" LastEditDate="2017-05-18T14:11:14.080" LastActivityDate="2017-05-18T14:11:14.080" Title="Which is more accurate for height measurement: GPS or barometer?" Tags="&lt;aircraft-design&gt;&lt;aircraft-systems&gt;&lt;altitude&gt;&lt;gnss&gt;" AnswerCount="5" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="29155" PostTypeId="2" ParentId="29154" CreationDate="2016-06-09T08:54:41.140" Score="2" Body="&lt;p&gt;This depends on the accuracy of the barometer and the weather, since the weather influences the air pressure. So even if you're standing still at the same altitude the barometer will show you different readings. This is why a pilot constantly has to adjust his altimeter. An altimeter is designed to measure the altitude above a fixed level. This is why pilots have to calibrate their altimeters before take-off with ATC.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS system, on the other hand, works with an accurate clock and the known positions of the satellites. The satellite sends out packages which are time stamped. The receiver receives these time-stamped packages and uses its own calibrated clock to determine the sequence. Comparing this to the know positions of the satellite at certain positions allow the use of triangulation formulas to solve for the position of the receiver.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The GPS system is owned by the US military and they have this graph about the accuracy improvements over the years.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/EwrZD.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/EwrZD.png&quot; alt=&quot;source: http://www.gps.gov/systems/gps/performance/accuracy/URE.pdf&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to answer your question, it is determined by the equipment you use, but cost wise it is cheaper to get an accurate reading from a GPS since it is also less influenced by the weather.&lt;/p&gt;&#xA;" OwnerUserId="15202" LastEditorUserId="5517" LastEditDate="2016-06-09T11:59:21.827" LastActivityDate="2016-06-09T11:59:21.827" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="29156" PostTypeId="2" ParentId="29154" CreationDate="2016-06-09T08:58:23.773" Score="2" Body="&lt;p&gt;Most likely GPS is more accurate, after all, it can calculate your location in three-dimensional space within a few feet. However, it's not really that usable, since GPS measures altitude from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Geoid&quot; rel=&quot;nofollow&quot;&gt;geoid&lt;/a&gt;. That said, new GPS-receivers should be able to correct the difference between the geoid and actual earth surface.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Baro-altimeters are also quite accurate, but only when the atmosphere is at &lt;a href=&quot;https://en.wikipedia.org/wiki/International_Standard_Atmosphere&quot; rel=&quot;nofollow&quot;&gt;ISA&lt;/a&gt;-conditions. Baro-altimeters are calibrated to ISA-atmosphere, and when any condition varies from this, you get an error. Some of those, for example temperature error, can be compensated for, but removing all potential errors is a tedious task.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I was geocaching and wanted the most accurate elevation information for my location, I would use an old-fashioned geographic map with elevation information.&lt;/p&gt;&#xA;" OwnerUserId="8321" LastActivityDate="2016-06-09T08:58:23.773" CommentCount="14" ContentLicense="CC BY-SA 3.0" />
  <row Id="29157" PostTypeId="2" ParentId="16371" CreationDate="2016-06-09T09:07:43.007" Score="1" Body="&lt;p&gt;You can find an estimate in the Roskam book &quot;Airplane Design Part VIII&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which is partial on google books:&#xA;&lt;a href=&quot;https://books.google.nl/books?id=GIHHFkd829cC&amp;amp;printsec=frontcover&amp;amp;dq=roskam+part+VIII&amp;amp;hl=en&amp;amp;sa=X&amp;amp;redir_esc=y#v=onepage&amp;amp;q=roskam%20part%20VIII&amp;amp;f=false&quot; rel=&quot;nofollow&quot;&gt;https://books.google.nl/books?id=GIHHFkd829cC&amp;amp;printsec=frontcover&amp;amp;dq=roskam+part+VIII&amp;amp;hl=en&amp;amp;sa=X&amp;amp;redir_esc=y#v=onepage&amp;amp;q=roskam%20part%20VIII&amp;amp;f=false&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, most Engineering Universities may have a copy of this series in their library. Most of the data you want to know, companies try their best to keep them private as it is information the competition would like to know.&#xA;In general most aircraft programs are based on an fixed set of sold units. If you know the cost of the individual units (aircraft) and the amount of units needed to sell to reach the break even point then you have a fairly good estimate over the program cost.&lt;/p&gt;&#xA;" OwnerUserId="15202" LastActivityDate="2016-06-09T09:07:43.007" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29158" PostTypeId="2" ParentId="29143" CreationDate="2016-06-09T09:43:55.203" Score="4" Body="&lt;p&gt;The aviation industry is strongly cognisant of these risks.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;At least one research programme has attempted to analyse them in depth, the &lt;a href=&quot;http://avsi.aero&quot; rel=&quot;nofollow&quot;&gt;Aerospace Vehicle Systems Institute&lt;/a&gt; (AVSI) Consortium Project #17 &lt;a href=&quot;http://avsi.aero/projects/current-projects/avionics-reliability/semiconductor-reliability/815-2/&quot; rel=&quot;nofollow&quot;&gt;Methods to Account for Accelerated Semiconductor Device Wear Out&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The project ran for six years until 2007 with a budget of ~US$1.2 million.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, the project's scope was analysis, development of guidelines, testing methods and so on, and did not include ways of addressing the fundamental problem.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A paper from the project &lt;a href=&quot;https://nepp.nasa.gov/files/16365/08_102_4_%20JPL_White.pdf&quot; rel=&quot;nofollow&quot;&gt;Microelectronics Reliability: Physics-of-Failure Based Modeling and Lifetime Evaluation&lt;/a&gt; discusses some of the issues in depth.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-09T09:43:55.203" CommentCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29159" PostTypeId="1" CreationDate="2016-06-09T11:32:39.307" Score="3" ViewCount="1579" Body="&lt;p&gt;I am studying for private pilot checkride and saw this form in an Oral Exam. Can you tell me where I can get this form online? If not, is there a better form for expiration and W&amp;amp;B data?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/6Bx4a.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/6Bx4a.jpg&quot; alt=&quot;Expiration and WB form&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="15337" LastEditorUserId="14661" LastEditDate="2016-06-09T15:47:51.167" LastActivityDate="2016-06-11T05:05:53.937" Title="What weight and balance form should I use for my checkride?" Tags="&lt;weight-and-balance&gt;&lt;student-pilot&gt;&lt;checkride&gt;" AnswerCount="2" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29160" PostTypeId="2" ParentId="29148" CreationDate="2016-06-09T12:53:08.083" Score="10" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;First of all, in the diagram they show the force on each wing being the same.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;In a &lt;strong&gt;steady&lt;/strong&gt; roll, i.e. when the roll rate is constant, the forces &lt;strong&gt;are the same&lt;/strong&gt;. A non-zero moment causes angular &lt;em&gt;acceleration&lt;/em&gt;, so when the aircraft is rolling with constant rate of roll, the moment must be zero, which means the lift on both wings have to be equal.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;That rules out difference in magnitude of lift as the source of the difference and leaves the difference in angle as the only plausible explanation. The explanation is correct.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;When you first deflect ailerons, the wing with aileron down does indeed start to produce more lift and the wing with aileron up less lift. This difference causes rolling moment, which causes the roll rate to increase. It already starts causing adverse yaw due to the difference in magnitude of lift too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However as the roll rate builds up, the angle of attack increases lift on the wing going down and decreases it on the wing going up until the lift equalizes and the roll rate stabilizes. At that point the lift is the same and the adverse yaw is caused by different direction of lift due to different angle of attack.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The fact that ailerons are deflected throughout the roll might lead you to think that there is still difference in lift. But there isn't. The aileron deflection just changes the roll rate in which the forces are in equilibrium.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also while the angle between realtive wing and the total aerodynamic force (which corresponds to the relation between lift and induced drag) is in general not constant, in this case all the factors it depends on — wing span, air speed and density — are (almost) the same for both wings, so the difference in angle of attack is the main factor for the direction of the resulting force.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And last, but not least: &lt;a href=&quot;http://www.av8n.com/how/&quot;&gt;How It Flies&lt;/a&gt; is very reliable regarding the physics (and most other things too). I would be very surprised to find an incorrect explanation there.&lt;/p&gt;&#xA;" OwnerUserId="524" LastActivityDate="2016-06-09T12:53:08.083" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="29161" PostTypeId="2" ParentId="29154" CreationDate="2016-06-09T15:01:27.660" Score="7" Body="&lt;p&gt;For surveying glacier movement, or a mountain range's growth/decay, GPS is more accurate.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For airplanes: refresh rate, reliability, and simplicity matter more. When it comes down to accuracy, ground augmented GPS provides ILS CAT I accuracy using &lt;a href=&quot;https://en.wikipedia.org/wiki/Localizer_performance_with_vertical_guidance&quot; rel=&quot;noreferrer&quot;&gt;LPV&lt;/a&gt;. So alongside refresh rate, and accuracy, comes the question of application. For airplanes in cruise, where separation matters, reliable devices are best.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;GPS signals can be jammed. As can be seen in the news lately in &lt;a href=&quot;https://www.aopa.org/news-and-media/all-news/2016/june/08/navy-cancels-planned-gps-outage-in-southern-california&quot; rel=&quot;noreferrer&quot;&gt;California&lt;/a&gt; and &lt;a href=&quot;http://www.mirror.co.uk/news/world-news/fresh-terror-fears-hackers-trying-8074849&quot; rel=&quot;noreferrer&quot;&gt;Egypt&lt;/a&gt;. And GPS signal can be lost due to ionospheric interference. So, any equipment that doesn't rely on external sources is safer.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2017-05-16T15:04:08.610" LastActivityDate="2017-05-16T15:04:08.610" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29162" PostTypeId="2" ParentId="29159" CreationDate="2016-06-09T15:58:31.453" Score="4" Body="&lt;p&gt;Use the same form you use every other time you go fly with your instructor.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you're at the point of preparing for a check-ride and you have never had a weight and balance form before, you may want to sue your flight instructor (...kidding, kind of).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If I approach a new trainer-airplane for the first time, I find out whether someone has made a weight and balance form for the plane yet and ask for a copy.  If not, one can be created using the data in the AFM in Excel or other spreadsheet program.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I like to make mine fully-automated as much as possible for day-to-day usage, but they can still be filled in manually for the purpose of demonstrating the understanding to an examiner.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you use LibreOffice Calc, you can download &lt;a href=&quot;http://www.mortensenaviation.com/files/N6285FDataSheet.ods&quot; rel=&quot;nofollow noreferrer&quot;&gt;the one I made for the plane I use&lt;/a&gt;.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/5dQtl.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/5dQtl.png&quot; alt=&quot;The spreadhseet&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/eH5Nv.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/eH5Nv.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If you try to open it with other software, it will look screwed up, but you can still get the idea.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The light blue shaded fields are the only ones that can have data entered into them.  The graph is created based on the weight data, and it automatically subtracts the fuel burn based on the flight duration.  So the two connected dots are the takeoff and landing C.G./Weight combinations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This was all done from scratch using the AFM's data.  It takes some work, but it is worth it.  Your instructor &lt;em&gt;should&lt;/em&gt; have something like this made already.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2016-06-11T05:05:53.937" LastActivityDate="2016-06-11T05:05:53.937" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29163" PostTypeId="2" ParentId="29159" CreationDate="2016-06-09T16:06:20.427" Score="2" Body="&lt;p&gt;As &lt;a href=&quot;https://aviation.stackexchange.com/users/62/pondlife&quot;&gt;Pondlife&lt;/a&gt; mentions in the comments there is no officially accepted form per say but you must insure that the values you use to calculate WB are out of the POH for &lt;em&gt;THE SPECIFIC&lt;/em&gt; aircraft you are flying that day. For your checkride you will be required to bring along all the paperwork for the plane which includes the POH. Since a given airframe may have small alterations like avionics variations or other modifications that effect empty weight and CG and the such the numbers from plane to plane may differ. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some POH's may have example worksheets like &lt;a href=&quot;http://www.wrongbrosftw.com/wp-content/uploads/2014/05/Warrior-PA28-161-POH.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this one for the Piper Warrior (see page 6-11)&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/LCEbd.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/LCEbd.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No matter the worksheet you use you should check the published procedure for calculating WB in the specific POH. Granted most of the procedures will be the same you should follow them none the less (you may be asked about how you arrived at a given value). My flight school had a form, I was comfortable with it so thats the one I used.   &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/e0f3Z.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/e0f3Z.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt; &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The video you linked (which I also watched many times before my check ride) is a bit dated but still relevant. You should note that the dates he is pointing to on that form are taken out of the log books. Your DPE may (mine did) ask you to show him the date in the actual logs that quick reference is not an official document. You should go over the POH and logs of the aircraft before your checkride to make sure that everything is in line and up to date. Strictly speaking you can bust your check ride if you show up in an aircraft that is not airworthy. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Real Wold Scenario:&lt;/em&gt; Every DPE varies the oral exam a bit so here is the WB stuff I had to answer. Before I even got there my DPE gave me his weight and had me to the WB for our XC flight (full fuel). He went over the numbers when I got there, I had the luxury of checking that a few times before showing up. After that he created a scenario for me (flights with friends etc). Had me run some WB to make sure we could make it, take off performance as well. He also asked me some questions about moving stuff around in the plane to shift CG if I needed to, as well as the effects of a far aft and far forward CG on the flight characteristics of the plane.  &lt;/p&gt;&#xA;" OwnerUserId="3677" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-06-09T16:15:26.253" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29164" PostTypeId="2" ParentId="28009" CreationDate="2016-06-09T17:14:49.057" Score="11" Body="&lt;p&gt;&lt;em&gt;Note: I focused more on changes in aviation hardware and software than what's currently used since the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3608/what-programming-languages-are-used-for-equipment-onboard-aircraft?rq=1&quot;&gt;question linked&lt;/a&gt; about programming languages is still current for &quot;new&quot; aircraft.  I do not wish to duplicate that question or its answers.  In my opinion C++, C#, and Ada will probably be the dominant programming languages for avionics for the next decade at least.&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;First, you've got to understand the life cycle of aircraft.  Many aircraft are in service for &lt;a href=&quot;https://aviation.stackexchange.com/questions/3370/why-are-older-airplanes-still-in-use/3928#3928&quot;&gt;more than 30 years&lt;/a&gt;.  The avionics do get updates (whether adding new features, fixing bugs, or adding in compliance to meet mandates). However, the bulk of the work is done during initial development of the software and hardware.  The configuration is then mostly fixed until that generation of avionics is replaced by the manufacturer or retrofitted by another manufacturer.  &lt;/p&gt;&#xA;&#xA;&lt;h2&gt;So What's Changed in Practice?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;If the avionics goes through a generational update (like CRT's to LCD screens), anything changed has to be worth the cost, so usually not much is changed.  Maybe the CPU, but definitely not the programming language. For example, the G1000 was out for 12 years before releasing another generation of hardware (although in the meantime they published numerous software updates for hardware compatibility and synthetic vision and such). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, &lt;a href=&quot;https://en.wikipedia.org/wiki/Avidyne_Entegra&quot; rel=&quot;nofollow noreferrer&quot;&gt;Avidyne Entegra&lt;/a&gt; was out for five years and continuously adding major features like data link weather and LPV approach before it finally upgraded the hardware in release 9 in 2009.  Falcon jets like the Falcon 900 had a &lt;a href=&quot;http://www.dassaultfalcon.com/en/MediaCenter/Newsd/Pages/PR%202012/Falcon-900-Operators-Showing-Strong-Interest-in-EASy-II-Flight-Deck-Nearly-50-Operators-Already-Flying-with-EASy-II-Equippe.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;software and hardware update&lt;/a&gt; to their avionics in 2011, but that upgrade was based on Primus Epic family of hardware and software, whose first generation was already 9 years old.  I believe all the 900's were still running the old 1996 hardware before the 2011 upgrade.  On the other end of the spectrum from these slow upgrades, the military's JSF system is &lt;a href=&quot;http://www.militaryaerospace.com/articles/print/volume-14/issue-5/features/special-report/f-35-jet-fighters-to-take-integrated-avionics-to-a-whole-new-level.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;designed to be upgraded easily&lt;/a&gt; every few years (but they don't say just how often).&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Why Not Make More Frequent Upgrades?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;What drives value in avionics isn't usually exotic new features and definitely not computing performance.  &lt;strong&gt;Value is driven by reliability, compliance to mandates, and safety-compliance&lt;/strong&gt;.  This requires features that are simple enough for the engineer and the pilot to understand and are robust enough to have hundreds of lives depend on it. So the new features being added generally require little extra performance, and there's little incentive for cutting-edge technology or the latest programming paradigms like cloud computing, machine learning, or object orientation.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;An engineer at Rockwell Collins &lt;a href=&quot;http://www.militaryaerospace.com/articles/print/volume-14/issue-5/features/special-report/f-35-jet-fighters-to-take-integrated-avionics-to-a-whole-new-level.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;stated&lt;/a&gt; something that applies to all avionics &quot;In the past, we struggled to fit everything we needed to do into the size of processor and speeds we had and how to get all those bits over the interfaces we had. With the processors we have now and fiber interfaces, that is no longer a concern... Now the problem is how to manage and design good, trouble-free software and test all the lines of code involved. So now that we have all the processing and bandwidth we need, we have to make sure we can use it and not design ourselves into a corner.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Verification is one of the biggest driving factors (and costs) in processor and programming language usage.  All hardware and software must have a &lt;a href=&quot;https://en.wikipedia.org/wiki/ARP4761&quot; rel=&quot;nofollow noreferrer&quot;&gt;safety level&lt;/a&gt; attached to it, with the most critical functions (like avionics for autoland) considered &quot;Level A&quot; meaning such a failure of the avionics could be catastrophic.  In order to achieve the stringent safety requirements for Level A software (which is often one such failure per 10^9 flight hours), the software and hardware need to be exhaustively tested to ensure nothing will ever go wrong.  That includes covering every condition on every line of code.  Most tools developed to work with your programming language and software architecture needs to be formally verified (usually called &quot;qualified&quot;) as well. On top of that all, costly flight testing needs to be done to evaluate any changes.  This creates a lot of inertia and means a complete overhaul of an existing product or starting from scratch for a new product just to get a &quot;faster system&quot; is often not cost-effective.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;What about support for new CPU features?&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Virtualization (allowing different OS's to act like they're running by themselves but are actually running with a layer between themselves and the bare hardware) and multi-core processing is now supported by some real-time OS's for commercial off-the-shelf processors. These have to follow the standards in DO-332 and other materials.  According to my &lt;a href=&quot;https://books.google.com/books?id=VlxfJ1qmZ8AC&amp;amp;q=multi%20core#v=snippet&amp;amp;q=multi%20core&amp;amp;f=false&quot; rel=&quot;nofollow noreferrer&quot;&gt;2013 text&lt;/a&gt;, this is still in the investigatory phase and no avionics with these features have been certified.  The main issue is that multi-core processors don't just have more features, but they have more features that are not comprehensively documented or testable. For more information on issues with use of multi-core see the &lt;a href=&quot;https://www.faa.gov/aircraft/air_cert/design_approvals/air_software/cast/cast_papers/media/cast-32.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;FAA's CAST 32&lt;/a&gt; and &lt;a href=&quot;http://www.ae-expo.eu/wp-content/uploads/2016/04/AAE2016_PaulParkinson_WindRiver_presentation.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this presentation&lt;/a&gt;.  &lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="14613" LastEditDate="2017-12-03T02:34:39.967" LastActivityDate="2017-12-03T02:34:39.967" CommentCount="9" ContentLicense="CC BY-SA 3.0" />
  <row Id="29165" PostTypeId="2" ParentId="29075" CreationDate="2016-06-09T23:05:04.117" Score="3" Body="&lt;p&gt;I think your question actually deserves a second answer, approaching it from another direction. You ask &quot;How can IATA make this claim?&quot;&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;What is actually being claimed?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In fact, the claim is quite slippery, and you'll notice that it is expressed in multiple different ways, &lt;em&gt;with different meanings&lt;/em&gt;, in different reports.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;These include: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&quot;no accidental hull losses&quot; (lead-in of IATA's &lt;a href=&quot;http://airlines.iata.org/data/safer-than-ever&quot; rel=&quot;nofollow noreferrer&quot;&gt;Safer than ever&lt;/a&gt; article)&lt;/li&gt;&#xA;&lt;li&gt;&quot;zero jet hull loss accidents involving passenger fatalities&quot; (the &lt;a href=&quot;http://airlines.iata.org/sites/default/files/Safer%20than%20ever%20PDF.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;infographic they link to from that page&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;&quot;No fatal jet hull losses&quot; (headline of &lt;a href=&quot;http://www.iata.org/pressroom/pr/Pages/2016-02-15-01.aspx&quot; rel=&quot;nofollow noreferrer&quot;&gt;IATA press release&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;(They're also written in a way that makes one wonder whether the &lt;em&gt;zero&lt;/em&gt; figure only refers to &quot;IATA Operational Safety Audit (IOSA)-registered carriers&quot;, though in fact I think that's not the case.)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Then you can read other reports that relate the news as &quot;&lt;a href=&quot;http://www.voanews.com/content/report-fewer-airline-accidents-in-2015/3191672.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;The number of airline accidents declined in 2015 with no deaths from jet aircraft reported&lt;/a&gt;&quot;, &quot;&lt;a href=&quot;http://time.com/4249996/airplane-accidents/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Not a single passenger died in a jetliner accident&lt;/a&gt;&quot;, and so on. No wonder people find it hard to see what is actually being claimed.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The six conditions&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;But anyway, working from IATA's own texts, the actual point is that in 2015 there were no incidents that were &lt;em&gt;all&lt;/em&gt; of the following:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;hull-losses (i.e. the aircraft was destroyed or written-off)&lt;/li&gt;&#xA;&lt;li&gt;accidental (deliberate acts don't count)&lt;/li&gt;&#xA;&lt;li&gt;involved fatalities...&lt;/li&gt;&#xA;&lt;li&gt;...of passengers&lt;/li&gt;&#xA;&lt;li&gt;of jet aircraft&lt;/li&gt;&#xA;&lt;li&gt;operated by airlines&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;I'm guessing that if we exclude any one of those conditions the figure will no longer be zero, but I'll leave that for others to show or not.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there's anything to be concluded from this, it's that words do actually mean things and when they change, so does meaning! &lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="22726" LastEditDate="2019-05-09T04:30:43.870" LastActivityDate="2019-05-09T04:30:43.870" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="29166" PostTypeId="1" AcceptedAnswerId="29167" CreationDate="2016-06-09T23:14:42.627" Score="6" ViewCount="305" Body="&lt;p&gt;I spend an unacceptable amount of time 'flying' around the country (U.S.) via Google Earth and I'm always zooming in on airplane symbols to have a look at airfields.  In the western U.S. there are lots of rural strips that have the little aircraft symbol on them which I'm presuming come from the FAA.  Some of these fields appear marginal at best as legitimate airfields, especially the ones that are obviously part of a farm or ranch.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question is what level of improvement is necessary for a field to be listed by the FAA as an airstrip?  Is there some minimum length, width, slope, etc.?  Is there some inspection that is done before you can get put on the charts and are there any ongoing checks to make sure the field is still there when the charts are updated?  Does the owner of a strip assume some ongoing obligation as a result of their strip showing up on a sectional?&lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2016-06-10T00:10:12.633" Title="Are there some minimum criteria for a field to be registered with the FAA as an airstrip?" Tags="&lt;airport&gt;&lt;airport-design&gt;&lt;airport-markings&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="29167" PostTypeId="2" ParentId="29166" CreationDate="2016-06-09T23:46:21.687" Score="4" Body="&lt;p&gt;Good question.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;14 CFR Part 139 requires FAA to issue airport operating certificates to airports that:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Serve scheduled and unscheduled &lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/139.5&quot; rel=&quot;nofollow&quot;&gt;air carrier aircraft&lt;/a&gt; with more than 30 seats;&lt;/li&gt;&#xA;&lt;li&gt;Serve scheduled air carrier operations in aircraft with more than 9 seats but less than 31 seats.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Also:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;VFR charts depict airport's hard and soft surface runways. Enroute charts depict airports having hard surface runways of at least 3000-foot in length. If your airport meets those criteria, you may contact the local Federal Aviation Administration, Airports District Office or Aeronautical Information Management, AJV-21, at 1-(866) 295-8236 to have your airport charted.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;That means for a private airstrip, it's your call as the owner to have it placed on a chart. Pretty cool.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;More: &lt;a href=&quot;https://www.faa.gov/licenses_certificates/airport_certification/&quot; rel=&quot;nofollow&quot;&gt;https://www.faa.gov/licenses_certificates/airport_certification/&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-06-10T00:10:12.633" LastActivityDate="2016-06-10T00:10:12.633" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29168" PostTypeId="1" AcceptedAnswerId="29182" CreationDate="2016-06-10T00:41:57.820" Score="6" ViewCount="5421" Body="&lt;p&gt;As I understand it, compression ratio is the max pressure inside the engine divided by the ambient air pressure. This is for turbojets and turbofans.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sea level pressure is about 100 kPa. An altitude of 10 km would have an ambient air pressure more like 26 kPa.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So you would think the compression ratio must drop 4x, but the thing is, does the turbine spin any faster at high altitudes to compensate?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So how does compression ratio change, if at all, from low to high altitudes?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Edit:&lt;/strong&gt; Maybe I should have started with hard figures. What are typical compression ratios for turbojets and turbofans?&lt;/p&gt;&#xA;" OwnerUserId="3674" LastEditorUserId="3674" LastEditDate="2016-06-10T23:43:54.960" LastActivityDate="2019-09-02T03:43:19.440" Title="How does compression ratio change, if at all, from sea level to higher altitudes?" Tags="&lt;jet-engine&gt;&lt;aircraft-performance&gt;" AnswerCount="1" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29169" PostTypeId="1" AcceptedAnswerId="29188" CreationDate="2016-06-10T08:49:10.930" Score="5" ViewCount="798" Body="&lt;p&gt;Everyone knows flight attendants represent the airline for the passengers, and have a commercial role by distributing meals, selling goods, managing the entertainment system, and receiving complaints.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/pSFfF.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/pSFfF.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;&lt;sup&gt;One of the well known glamour airline-clichés for flight attendants, circa 1960 (&lt;a href=&quot;http://www.bianoti.com/vintage-flight-attendant-poster.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;source&lt;/a&gt;).&lt;/sup&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Apart from this commercial role, they also provide the regulatory information about safety. But I feel there is more to know related to their technical role.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What are the non commercial missions or responsibilities of a flight attendant, what are they accountable for? did that role change over years? How are they trained? What is their career path?&lt;/p&gt;&#xA;" OwnerUserId="3201" LastEditorUserId="3201" LastEditDate="2016-06-11T16:13:09.707" LastActivityDate="2016-06-11T16:13:09.707" Title="What is the technical role of a flight attendant?" Tags="&lt;regulations&gt;&lt;airlines&gt;&lt;flight-attendant&gt;" AnswerCount="2" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="29172" PostTypeId="1" AcceptedAnswerId="29174" CreationDate="2016-06-10T11:32:56.233" Score="14" ViewCount="5267" Body="&lt;p&gt;A new airliner was launched on June 8, 2016 by the Russian company &lt;a href=&quot;http://eng.irkut.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;Irkut Corporation&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/2K9nf.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/2K9nf.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&#xA;Source: &lt;a href=&quot;https://www.flightglobal.com/&quot; rel=&quot;nofollow noreferrer&quot;&gt;https://www.flightglobal.com/&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The airliner looks good on paper:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Empty plane weight is reduced due to composite and prospective alloy materials and lighter new generation onboard systems&lt;/li&gt;&#xA;&lt;li&gt;Wide cabin (3.81m), MC-21's cabin is wider than the cabin of an&#xA;Airbus A320 by 12 cm and a Boeing 737 by 28 cm. As a result, two&#xA;passengers can walk through the aisle without blocking each other.&#xA;The wide cabin also supports the biggest luggage racks in its class&#xA;in order to accomplish the goals of decreasing MC-21's turn-around&#xA;time at the airport (important for charter and low-cost carriers),&#xA;providing better comfort for passengers, and making the cabin more&#xA;suitable for carriers' purposes&lt;/li&gt;&#xA;&lt;li&gt;Relatively to the current models MC-21’s engines will emit 20% less&#xA;СО2 per passenger seat&lt;/li&gt;&#xA;&lt;li&gt;High cost operational effectiveness, international certification&#xA;under AR IAC, EASA, FAA requirements, individual logistic and&#xA;maintenance support during all life cycle will make the aircraft&#xA;attractive both for Russian and foreign carriers&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Source: &lt;a href=&quot;https://en.wikipedia.org/wiki/Irkut_MC-21&quot; rel=&quot;nofollow noreferrer&quot;&gt;Wikipedia&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Almost all of the orders look like they come from Russian airlines. But why haven't any US/UK/Japanese etc. airlines ordered any planes?&lt;/p&gt;&#xA;" OwnerUserId="1678" LastEditorUserId="1678" LastEditDate="2016-06-11T05:35:36.247" LastActivityDate="2016-06-11T05:35:36.247" Title="Why have none of the US /UK/Japanese airlines ordered the Irkut MC-21 yet?" Tags="&lt;airlines&gt;" AnswerCount="2" CommentCount="14" FavoriteCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29174" PostTypeId="2" ParentId="29172" CreationDate="2016-06-10T12:29:27.733" Score="47" Body="&lt;p&gt;Ordering an aircraft is a very complex business, and implicates a number of matters that don't actually (on the surface, anyway) have anything to do with the aircraft itself. Consider this from the point of view of a western European or north American airline. &lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Broadly political obstacles&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;These could include:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;international trade agreements and disputes (Russia's relations with much of the world are not very friendly at present)&lt;/li&gt;&#xA;&lt;li&gt;existing suppliers (&quot;Lovely relationship we've enjoyed since the 1970s; it would be a shame if &lt;em&gt;someone&lt;/em&gt; carelessly trampled it underfoot and soured it.&quot;)&lt;/li&gt;&#xA;&lt;li&gt;governments and politicians (&quot;Oh really? Well, it certainly has been nice supporting you fearlessly in Parliament/the Ministry/Congress/against my opponents who hate your guts. Bye!&quot;)&lt;/li&gt;&#xA;&lt;li&gt;national expectation (&quot;Traitors!&quot;)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;History and reputation&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Russian (like Chinese) design, technology, engineering and manufacturing have a reputation in the west that works against them. These things take &lt;em&gt;decades&lt;/em&gt;, not years, to be overcome by stellar achievements in those fields (consider how long it took &quot;Japanese&quot; to become regarded as a positive rather than a negative adjective when applied to products).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However unfairly, this feeds in to other obstacles:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;customers (&quot;Get on a &lt;em&gt;Russian&lt;/em&gt; airliner? No way!&quot;) &lt;/li&gt;&#xA;&lt;li&gt;shareholders (&quot;You're proposing to buy a what?!&quot;) &lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;Risks&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Then, it doesn't make sense to buy one plane to &quot;try it out&quot;. Even with a single aircraft of the type, you'd need the same training, certification, engineering support, etc etc as if you had a fleet of them.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, you'd be looking at a fleet of them, and now you're facing the purchase of a fleet of aircraft that very much represent an unknown quantity. It's a huge, huge risk; no wonder airlines cleave so strongly to the Airbus/Boeing duopoly - maybe it's not entirely to their economic advantage, but they don't expect too many surprises, which is arguably more important.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Some of these risks: &lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;are simply technical (&quot;How good will the product turn out to be in the long run?&quot;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;are economic (&quot;Could the trade climate make spare parts and maintenance prohibitively expensive in the future?&quot;)&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;hinge on international relations (&quot;Could our government ban us from working with this supplier in future? Could a meddling Kremlin disadvantage us?&quot;).&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;h1&gt;How could it work? Will it ever work?&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Give it a couple of decades. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If airlines in places like India, Indonesia, Brazil, with fewer historical attachments and political obstacles than in the west, find that the aircraft and manufacturer prove to be good for them, bit by bit we may see that influence trickle into western airlines, especially as those non-western airlines and the economies they belong to expand and become more influential themselves.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-10T12:29:27.733" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29175" PostTypeId="2" ParentId="29172" CreationDate="2016-06-10T12:31:15.713" Score="9" Body="&lt;p&gt;CityJet has taken delivery of the SuperJet SSJ100s, one of the first carriers in Europe to fly a Russia made aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason that other airlines haven't placed an order is the fact that you need a completely new maintenance facility, crew, workers, parts storage etc, to maintain the aircraft or you need to completely outsource the maintenance. Since there are no other European airlines operating them you need to fly them to Eastern-Europe for maintenance. (From the US is this difficult given the range of the aircraft)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The second item is no problem for low cost carriers that do not do the maintenance themselves. But low cost carriers prefer to fly one type of aircraft (Easyjet, Ryanair) This saves cost on crews and facilities since everything is focused at one type of aircraft (or family). So a new low cost carrier could consider them, but when looking at the history of low cost carriers is that they start with old planes and when successful replace them with newer and cheaper to operate aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And lastly the unknown trackrecord and new market (for Irkut) does play a role, Airbus for example had quite some difficulties to sell their aircraft on the US market when they first started, some legacy of that is still visible since most of the US airlines fly an all Boeing fleet. Airbus did get their share of the market by giving huge discounts to US airlines ordering aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So to conclude, the airline industry is a high tech environment which on the other hand can be very conservative and does a lot of risk management when considering the purchase of aircraft.&lt;/p&gt;&#xA;" OwnerUserId="15202" LastActivityDate="2016-06-10T12:31:15.713" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="29176" PostTypeId="1" CreationDate="2016-06-10T13:21:24.403" Score="10" ViewCount="1492" Body="&lt;p&gt;Why we rarely see an A320 (or equivalent aircraft) on a long route with all premium business seats or an A380 (or equivalent aircraft) with high density seating and on a short route?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;On top of that, it is a much easier task to design a long range light aircraft and a short range heavy/high capacity aircraft, so why have no airliners (as far as I know) ever been designed with these characteristics in mind?&lt;/p&gt;&#xA;" OwnerUserId="15347" LastEditorUserId="14897" LastEditDate="2018-03-21T23:11:59.657" LastActivityDate="2018-03-21T23:11:59.657" Title="Why there is such a strong correlation between the range of an airliner and its passenger capacity?" Tags="&lt;aircraft-design&gt;&lt;airliner&gt;&lt;aircraft-performance&gt;&lt;range&gt;&lt;seating-capacity&gt;" AnswerCount="5" CommentCount="7" FavoriteCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29177" PostTypeId="2" ParentId="29176" CreationDate="2016-06-10T13:54:33.310" Score="4" Body="&lt;p&gt;Basically the airlines need keep their planes always flying, parking them idle on the airport just costs money. &lt;em&gt;Parking&lt;/em&gt; a big plane and waiting a complete day until it gets &lt;em&gt;full with passengers&lt;/em&gt; is expensive, &lt;em&gt;flying&lt;/em&gt; a small plane a long time while passengers &lt;em&gt;already waiting&lt;/em&gt; for the next flight is lost money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In the past big planes were build for short and medium-routes, like the B747-100SR/300-SR or the A300 (first time two aisles one a twin-engine?). The 747-SR was used a lot &lt;em&gt;inside Japan&lt;/em&gt;, while the A300 founds it first customers &lt;em&gt;inside&lt;/em&gt; USA. But the airlines don't buy them anymore.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Consider that on short routes you are often connecting smaller airports with fewer passengers per trip, therefore a smaller plane is more efficient. On the other side, most jet-engines become more efficient when they are bigger, furthermore long boarding times are not a problem on long distance flights.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Also, one, two or three flights during a day on long routes are okay for passengers on long routes (selecting a round about departure/arrival), while on short routes you may need a flight every hour (selecting exact departure/arrival).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notable exceptions are current B737-700ER and A319LR, both can fly around 10.000 km. I don't know the sales figures, but I think only customers with special needs buy them.&lt;/p&gt;&#xA;" OwnerUserId="1084" LastEditorUserId="5517" LastEditDate="2016-06-10T14:59:21.847" LastActivityDate="2016-06-10T14:59:21.847" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29180" PostTypeId="2" ParentId="29176" CreationDate="2016-06-10T15:02:50.687" Score="7" Body="&lt;p&gt;A big part of the difference in range between small and large aircraft is simply mathematical. When you make a 3D object larger, area increases with the square of length while volume increases with the cube. The A320 has a wingspan of 35.8m, carries 150 (2-class), and carries 24,210L of fuel (standard). The A380 has a wingspan of 79.75m, about twice the dimensions of the A320. However, the passenger capacity increases by a factor of 4 to 644 (2-class), and the fuel capacity increases by over a factor of 10 to 320,000L. There is simply more room for fuel in a larger aircraft. Smaller aircraft may have options to carry additional fuel talks to increase range. Note that this trend also applies to &lt;a href=&quot;https://en.wikipedia.org/wiki/Business_jet&quot; rel=&quot;nofollow noreferrer&quot;&gt;business jets&lt;/a&gt; despite their market having less of a correlation between range and passenger demand.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In addition to the geometrical constraints, &lt;a href=&quot;https://aviation.stackexchange.com/q/13150/1696&quot;&gt;airlines have other reasons for not operating large planes on short routes&lt;/a&gt;, or vice versa, more often. Using small planes allows for more frequent service and more flexibility even if there is enough demand to use a smaller number of larger aircraft.&lt;/p&gt;&#xA;" OwnerUserId="1696" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:54.737" LastActivityDate="2016-06-10T15:02:50.687" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29181" PostTypeId="1" CreationDate="2016-06-10T15:28:36.740" Score="9" ViewCount="648" Body="&lt;p&gt;I was in an aircraft yesterday waiting for its turn in the departure queue on the taxiway and noticed that the windsock was showing a direction approximately 30 degrees but directed &lt;em&gt;along&lt;/em&gt; the direction we were entering the runway in. i.e. The parallel component would point in the take-off direction &amp;amp; not against it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Made me wonder: &lt;em&gt;Are there instances when lined up aircraft have to be made to taxi to the other end of a runway due to a last minute wind direction reversal?&lt;/em&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Never happened to me, nor seen it mentioned in any ATC conversations / videos online so made me wonder. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course, if the parallel component is smaller than the allowable tailwind for the aircraft then  I guess it does not matter?&lt;/p&gt;&#xA;" OwnerUserId="7611" LastEditorUserId="7611" LastEditDate="2016-06-11T02:26:25.233" LastActivityDate="2018-11-08T04:17:26.523" Title="Has reversing the active runway direction ever led to lined-up aircraft taxiing to the other end of the runway?" Tags="&lt;air-traffic-control&gt;&lt;takeoff&gt;&lt;wind&gt;" AnswerCount="2" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29182" PostTypeId="2" ParentId="29168" CreationDate="2016-06-10T16:18:27.323" Score="7" Body="&lt;p&gt;The compression ratio of the turbo machinery will not change with altitude as long as the speed of the compressor does not change (excluding Reynolds number effects). This will lower the maximum pressure in parallel with the outside pressure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;However, to create the same lift at altitude, the aircraft has to fly faster. In 10 km, where the air density is roughly 1/4 of sea level density, the airplane has to fly twice as fast. Also, air temperature drops with altitude, so the &lt;a href=&quot;https://aviation.stackexchange.com/questions/3693/how-does-altitude-affect-the-speed-of-sound/3695?s=1%7C0.2855#3695&quot;&gt;flight Mach number increases&lt;/a&gt; even more. And this Mach number determines how much &lt;a href=&quot;https://aviation.stackexchange.com/questions/14710/what-is-a-ramjet/14717?s=1%7C0.2432#14717&quot;&gt;ram compression&lt;/a&gt; happens ahead of and in the intake. Flying fast will increase the intake pressure level, which partially compensates for the lower atmospheric pressure. Since the pressure rises with the square of the Mach number, fast airplanes have a clear advantage here.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Take the &lt;a href=&quot;https://en.wikipedia.org/wiki/Concorde&quot; rel=&quot;nofollow noreferrer&quot;&gt;Concorde&lt;/a&gt;: Its &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce/Snecma_Olympus_593&quot; rel=&quot;nofollow noreferrer&quot;&gt;Olympus 593&lt;/a&gt; had a compression ratio of measly 12, but the precompression around the intake added another factor of 7 at Mach 2, so the total pressure ratio between the peak pressure in the engine and outside air was over 80! Admittedly, this air pressure was only 76 mbar at the cruising altitude of the Concorde, so the absolute peak pressure in the engine was a much less impressive 6 bar.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Typical compression ratios&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;To answer the question about typical compression ratios: This correlates strongly with the age of the design: The first operational turbojet, the Junkers Jumo 004 of 1943, had a compression ratio of just 3.2 using 7 compressor stages. The more recent &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurojet_EJ200&quot; rel=&quot;nofollow noreferrer&quot;&gt;Eurojet EJ200&lt;/a&gt; of the Eurofighter achieves a compression ratio of around 26 with a similar size and weight using 8 compressed stages, but produces almost 7 times more thrust. The main difference is better aerodynamics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The &lt;a href=&quot;https://en.wikipedia.org/wiki/Rolls-Royce_Trent_XWB&quot; rel=&quot;nofollow noreferrer&quot;&gt;most recent civilian engines&lt;/a&gt; achieve a pressure ratio of around 50 using 15 compressor stages. They can afford to compress the air more because they try to heat and accelerate the air as little as necessary during the combustion process. Since the maximum heat inside the engine is limited by the materials used, a higher compression in military engines would leave less thermal margin for combustion heating. The higher nozzle velocities of supersonic-capable engines are best achieved with less compression and more combustion heating.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Here is a plot of the pressure ratio trends for commercial transport engines (&lt;a href=&quot;http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node84.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;Epstein, 1998&lt;/a&gt;)&#xA;&lt;a href=&quot;https://i.stack.imgur.com/Iunb9.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/Iunb9.jpg&quot; alt=&quot;Pressure ratio trends for commercial transport engines (Epstein, 1998)&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;" OwnerUserId="1961" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:55.230" LastActivityDate="2016-11-27T06:22:05.243" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29183" PostTypeId="2" ParentId="12173" CreationDate="2016-06-10T17:19:58.430" Score="6" Body="&lt;p&gt;Many other answers have covered lights for seeing on the ground, which are invaluable during taxiing, takeoff and landing.  They've also covered how most obstacles (like other planes) should be illuminated to be seen (according to &lt;a href=&quot;http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/1028657&quot; rel=&quot;nofollow noreferrer&quot;&gt;Advisory Circular 70/7460-1L&lt;/a&gt; in the US).  I'm going to cover the other ways that an aircraft can &quot;see&quot; what's around it. IFR navigation and &lt;a href=&quot;https://aviation.stackexchange.com/questions/22052/what-steps-can-pilots-take-to-mitigate-the-risk-of-controlled-flight-into-terrai/22073#22073&quot;&gt;avoiding controlled flight into terrain&lt;/a&gt; are related topics.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The answer depends somewhat on whether we're talking about visual flight rules or instrument flight rules.  Visually spotting lit obstacles is far more important if you're not instrument-rated.   Of course, &lt;em&gt;planes don't have to visually see obstacles to avoid them&lt;/em&gt;. Properly trained pilots can fly IFR in zero visibility, so they have plenty of tools to identify threats ahead that they can't see.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Charts&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Aircraft can fly in low visibility situations where even lights won't do you much good.  This is done in large part using careful navigation and reference to charts.  Sectional charts are required to show peaks, towers, and other obstructions as shown in the legend below.  Approach plates and procedures may also list smaller obstacles particularly close to the runway.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/FcAsJ.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FcAsJ.jpg&quot; alt=&quot;How obstacles are marked on sectional charts&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;You'll notice that the sectional below has the obstructions marked, as well as a big 07 in the right hand bottom.  That 07 means that the highest terrain or obstruction in the right hand box on the image below (basically everything east of Logan Intl Airport, outlined by straight lines with tick marks) is 700 feet, including a small margin and rounding, so if you're flying safely above that altitude you can avoid obstacles.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/byvBp.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/byvBp.jpg&quot; alt=&quot;Sectional chart excerpt for Boston&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Synthetic Vision&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;A new emerging technology is &lt;a href=&quot;https://en.wikipedia.org/wiki/Synthetic_vision_system&quot; rel=&quot;nofollow noreferrer&quot;&gt;synthetic vision&lt;/a&gt;, as mentioned in SierraSkyport's answer.  This system combines precision location information with very detailed terrain and obstacles databases to provide a view of the surrounding area.&lt;br&gt;&#xA;This is sometimes combined an &lt;a href=&quot;https://aviation.stackexchange.com/questions/23722/what-is-an-enhanced-vision-system/23723#23723&quot;&gt;enhanced vision system&lt;/a&gt; with an near-IR camera to see in darkness and through fog and clouds, and this clear camera-based view of the surrounding area is often overlaid on the center of the synthetic vision display.  I've seen a near-IR camera in action and you can actually make out features like the edge of the runway and buildings, even in very low visibility.&#xA;&lt;a href=&quot;https://i.stack.imgur.com/FdBA0.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FdBA0.jpg&quot; alt=&quot;Synthetic vision system&quot;&gt;&lt;/a&gt;&#xA;(Image by Honeywell, provided with Permission)&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;TCAS and ADS-B&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Your major obstacles when above the ground are other aircraft (I don't know what else you'd hit in the air, &lt;a href=&quot;http://www.scientificamerican.com/article/is-it-possible-that-a-met/&quot; rel=&quot;nofollow noreferrer&quot;&gt;meteorites&lt;/a&gt;?) Any aircraft equipped with a mode-C or mode-S transponder is &quot;visible&quot; to a plane with TCAS, and the TCAS system will provide traffic alerts for nearby aircraft (and guidance for how to resolve the conflict if the intruder gets close enough and it's a TCAS II system).&#xA;&lt;a href=&quot;https://i.stack.imgur.com/oB4eG.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/oB4eG.jpg&quot; alt=&quot;TCAS Display&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast&quot; rel=&quot;nofollow noreferrer&quot;&gt;ADS-B in&lt;/a&gt; also provides a traffic information for any nearby aircraft equipped with ADS-B out (which thanks to mandates is becoming very common). If you have ADS-B out as well as ADS-B in, you'll additionally receive radar information for all aircraft from ATC over a service called TIS-B. ADS-B is often supplied integrated into a mode-s transponder, but this is not always the case, so you could have ADS-B out and ADS-B in but not a TCAS-compatible transponder.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;TAWS, GPWS, and Radar altimeter&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;For avoiding the ground these systems provide some information to avoid a controlled flight into terrain.  Terrain  awareness warning systems (TAWS) and ground proximity warning systems (GPWS) (the two are sometimes synonymous) are now required by the FAA on all large turbine and turbojets.  These systems warn if you're descending too fast, below the glideslope, or flying too close to terrain, based on a radar altimeter.  Even without this system, you may have a radar altimeter to monitor your height above terrain.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Radar&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Weather_radar&quot; rel=&quot;nofollow noreferrer&quot;&gt;Weather Radar&lt;/a&gt; (or Stormscopes), XM radio, and ADS-B all provide excellent information about weather ahead that you can't see.  Most non-military aircraft &lt;a href=&quot;https://www.quora.com/Why-dont-commercial-aircraft-have-their-own-radar&quot; rel=&quot;nofollow noreferrer&quot;&gt;do not have primary radar&lt;/a&gt; for seeing things other than weather. Since ATC provides their own primary radar information over TIS (ADS-B traffic information), there is not much need to have a primary radar on the aircraft.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;ATC&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;In a worst case scenario ATC has tools like minimum safe altitude warning systems and short-term conflict alerts and &lt;a href=&quot;https://aviation.stackexchange.com/questions/29351/how-much-responsibility-does-atc-have-to-alert-a-flight-about-being-in-a-dangero&quot;&gt;may alert you&lt;/a&gt; if you're about to run into terrain or another aircraft.  As far as I understand, this isn't supposed to be your primary method of avoiding obstacles though, even in IFR conditions.&lt;/p&gt;&#xA;&#xA;&lt;h2&gt;Night Vision Goggles&lt;/h2&gt;&#xA;&#xA;&lt;p&gt;Of course, if you really need to see far ahead of you in dangerous terrain, you can use &lt;a href=&quot;https://iflyamerica.org/nightvision.asp&quot; rel=&quot;nofollow noreferrer&quot;&gt;night vision goggles&lt;/a&gt;.  Your aircraft needs to meet certain requirements and you need training, however.&lt;/p&gt;&#xA;" OwnerUserId="14613" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.883" LastActivityDate="2016-08-11T16:31:13.523" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29184" PostTypeId="2" ParentId="29176" CreationDate="2016-06-10T19:41:27.127" Score="2" Body="&lt;p&gt;There are two design reasons for this:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Airline routes&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;In the hub-and-spoke system most large airlines use, larger volumes of passengers are concentrated into a few airport hubs then moved greater distances between hubs. In that system, there is little need for long distance/small passenger aircraft.&lt;/p&gt;&#xA;&#xA;&lt;ol start=&quot;2&quot;&gt;&#xA;&lt;li&gt;Fuel Capacity&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;A larger plane can carry more fuel and thus go farther. Yes, you can get a 737 configured for business that can go as far as an early 747 but, when loaded like that, it cannot carry very many people. A BBJ 737 with full fuel can only carry about 2500 lbs—about 15 passengers with no bags, no food, no nothing.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastActivityDate="2016-06-10T19:41:27.127" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29185" PostTypeId="2" ParentId="29181" CreationDate="2016-06-10T19:53:07.233" Score="11" Body="&lt;p&gt;What you are describing does happen. The runway change is a major event at a big airport and it usually occurs once a day. This becomes a major transition because landing aircraft have to be switched to the other end. AND, areas served by a single approach control, the change has to be coordinated with the other airports. Note that lines of aircraft waiting to take off rarely occur unless the airport is very busy and has few runways.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Thus, the runway change generally occurs over time (half an hour). &lt;/p&gt;&#xA;&#xA;&lt;p&gt;If there is a sudden, unpredicted wind change, generally, aircraft that are already at the &quot;wrong&quot; end of the runway are allowed to continue using it if they are able to do so.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So yes, aircraft will on occasion have to move to the other end of the runway.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I have seen this more frequently at busy general aviation airports than at commercial airport.&lt;/p&gt;&#xA;" OwnerUserId="2129" LastEditorUserId="3386" LastEditDate="2018-11-08T04:17:26.523" LastActivityDate="2018-11-08T04:17:26.523" CommentCount="3" ContentLicense="CC BY-SA 4.0" />
  <row Id="29186" PostTypeId="2" ParentId="29150" CreationDate="2016-06-10T19:54:07.413" Score="3" Body="&lt;p&gt;The pivot point will be where an imaginary line through the rear wheels and an imaginary line perpendicular to the front wheel intersects.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/FDM0Y.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/FDM0Y.jpg&quot; alt=&quot; pivot point illustration&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if θ is the steering angle and d is the distance between the front wheel and a point halfway between the rear wheels then &lt;/p&gt;&#xA;&#xA;&lt;p&gt;X = d • tan(θ)&lt;/p&gt;&#xA;&#xA;&lt;p&gt;will give you the distance from the point between the rear wheels to the pivot point.&lt;/p&gt;&#xA;" OwnerUserId="8730" LastActivityDate="2016-06-10T19:54:07.413" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29187" PostTypeId="1" AcceptedAnswerId="29289" CreationDate="2016-06-10T20:19:59.083" Score="3" ViewCount="1070" Body="&lt;p&gt;I have moved to another place from current address with in same city, Do I have to change my address to the new one on my FAA Student Pilot License? If yes, how do I do it?&lt;/p&gt;&#xA;" OwnerUserId="9353" LastEditorUserId="62" LastEditDate="2016-06-14T01:03:19.613" LastActivityDate="2016-06-14T03:43:45.803" Title="How should I handle a change of address for a Student Pilot License in the USA?" Tags="&lt;faa-regulations&gt;&lt;pilot-certification&gt;&lt;student-pilot&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29188" PostTypeId="2" ParentId="29169" CreationDate="2016-06-10T21:43:16.093" Score="12" Body="&lt;p&gt;I flew for a major airline as a flight attendant for 7 years.  The FAA requires flight attendants on board for the safety aspect of passenger service and sets the minimum number based on the aircraft's passenger capacity.  We usually flew with at least one more crew member than the minimum required by the FAA.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Our FAA mandated duties include safe boarding, including stowage of personal articles, arming the evacuation slides after the doors are closed, a safety briefing prior to departure, verification that the cabin is safe for flight, inflight enforcement of pilot instructions (usually return to seats and fasten seat belts), and to render passenger assistance as necessary for flight safety.  Same for pre-landing and de-planing.  First aid training (including how to deliver a baby in-flight) was rarely seen by the public.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Annually we would be required to attend jet recurrent training where we reviewed NTSB accident reports with an emphasis on cabin crew responses to emergencies, review of first aid and CPR techniques, re-testing of our knowledge of the location and how to use all the safety equipment on board, including life preservers, life rafts, and emergency slide procedures.  We were also briefed on any changes to FAA mandated procedures and tested on everything.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;We were trained to be current on every aircraft the company flew so that we had maximum flexibility for our scheduling.  At the time I flew, this would have been B-727, B-707,B-757, B-767, DC-9, DC-9 stretch, and L-1011.  That meant we had to know the location of every flashlight, first aid kit, supplemental oxygen bottle, safety briefing kit, life raft, life preserver, safety exit, safety lighting, etc. for every aircraft type we flew.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The normal passenger service duties that passengers see such as food and beverage services, in-flight entertainment and generally trying to be accommodating, were in addition to the FAA required duties and were entirely up to the company's discretion to provide and train us for.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The FAA mandated safety aspects of flight attendant duties have become so integrated with the normal flow of a commercial flight they can go nearly unnoticed, especially for routine travelers.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;And no, we weren't trained how to land a plane in case all the pilots got sick at the same time and passed out.  &lt;/p&gt;&#xA;" OwnerUserId="9161" LastActivityDate="2016-06-10T21:43:16.093" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29189" PostTypeId="1" CreationDate="2016-06-10T22:01:09.027" Score="8" ViewCount="434" Body="&lt;p&gt;&lt;a href=&quot;https://www.mhi-global.com/products/detail/engineering_mals.html&quot; rel=&quot;noreferrer&quot;&gt;Mitsubishi's Air Lubrication System&lt;/a&gt; blows a fine sheet of bubbles below the hull of a ship. The bubbles form a &quot;carpet&quot; on the hull, reducing friction. See &lt;a href=&quot;http://www.gizmag.com/mitsubishi-air-lubrication-system/21196/&quot; rel=&quot;noreferrer&quot;&gt;Gizmag&lt;/a&gt; (yes, sorry) for some more information.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's &lt;strong&gt;assume&lt;/strong&gt; that such a similar mechanism - something like the surface of an &lt;a href=&quot;https://en.wikipedia.org/wiki/Air_hockey&quot; rel=&quot;noreferrer&quot;&gt;air-hockey table&lt;/a&gt; perhaps - would be feasible to implement on an aircraft.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;What aerodynamic effect would it have? Could it, &lt;strong&gt;assuming it were feasible&lt;/strong&gt;, provide any benefit to an aeroplane/helicopter/dirigible?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="14897" LastEditDate="2016-12-11T04:37:09.083" LastActivityDate="2018-06-08T22:02:44.223" Title="Can planes benefit from Mitsubishi's Air Lubrication System?" Tags="&lt;aircraft-design&gt;&lt;aerodynamics&gt;&lt;drag&gt;" AnswerCount="1" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29190" PostTypeId="1" CreationDate="2016-06-10T22:34:28.330" Score="4" ViewCount="267" Body="&lt;p&gt;As you might gather from &lt;a href=&quot;https://aviation.stackexchange.com/questions/29189&quot;&gt;Can planes benefit from Mitsubishi&amp;#39;s Air Lubrication System?&lt;/a&gt; I'm interested in what possibilities there are for radically different approaches to aircraft body surfaces.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Aircraft body surfaces appear to be as smooth as possible, but not all things that fly well are smooth:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;golf balls are dimpled (see the very interesting discussion of &lt;a href=&quot;https://aviation.stackexchange.com/questions/24752&quot;&gt;Is a golf ball surface a good idea for wings or fuselage?&lt;/a&gt;)&lt;/li&gt;&#xA;&lt;li&gt;birds are feathered&lt;/li&gt;&#xA;&lt;li&gt;sharks have &lt;a href=&quot;https://en.wikipedia.org/wiki/Fish_scale#Placoid_scales&quot; rel=&quot;nofollow noreferrer&quot;&gt;placoid scales&lt;/a&gt; (yes, I am aware that sharks don't &lt;em&gt;actually&lt;/em&gt; fly through the air...)&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;Has scientific or industry research indicated useful possibilities in new surfaces for aircraft body skins - or maybe alternatives to skins altogether?&lt;/p&gt;&#xA;" OwnerUserId="14197" LastEditorUserId="-1" LastEditDate="2017-04-13T12:59:58.323" LastActivityDate="2016-06-13T13:10:18.187" Title="Has research into the aerodynamic properties of non-smooth surfaces suggested any promising directions for future aircraft design?" Tags="&lt;aerodynamics&gt;" AnswerCount="1" CommentCount="5" ContentLicense="CC BY-SA 3.0" />
  <row Id="29192" PostTypeId="2" ParentId="29189" CreationDate="2016-06-10T23:01:23.927" Score="9" Body="&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/CdSTa.jpg&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/CdSTa.jpg&quot; alt=&quot;enter image description here&quot; /&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&lt;p&gt;NASA tested a &lt;a href=&quot;https://aviationweek.com/awin-featured-story/boeing-nasa-test-active-flow-control-tail&quot; rel=&quot;noreferrer&quot;&gt;similar concept&lt;/a&gt;. They call it &lt;strong&gt;Active Flow Control,&lt;/strong&gt; or AFC.&lt;/p&gt;&#xA;&lt;blockquote&gt;&#xA;&lt;p&gt;A full-scale 757 tail, equipped with active flow control, has demonstrated increased rudder effectiveness in wind-tunnel tests by Boeing and NASA that could lead to smaller, lower-drag vertical tails.&lt;/p&gt;&#xA;&lt;p&gt;&amp;quot;Sweeping jet&amp;quot; AFC actuators were mounted on one side of the fixed stabilizer, just upstream of the rudder hinge line to blow on to the leading edge of the deflected surface. The 37 actuators were supplied with variable mass-flow pressurized air from an external source and were individually addressable so that different spacings and zones could be tested.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&lt;p&gt;Tail fins are huge to help compensate for engine failures. But with such system blowing pressurized air out of holes upstream from the rudder, manufacturers can design smaller tails to save on drag and weight.&lt;/p&gt;&#xA;&lt;hr /&gt;&#xA;&lt;p&gt;Another system that works by suction (not blowing) at the leading edge is on the 787-9/10. It is used for both the horizontal and vertical stabilizers on the -9, but Boeing dropped the horizontal stabilizer system on the -10. There were plans to use it on the upcoming 777X, but Boeing &lt;a href=&quot;http://aviationweek.com/commercial-aviation/boeing-ditches-drag-reduction-system-777x&quot; rel=&quot;noreferrer&quot;&gt;dropped it&lt;/a&gt;. That system is called &lt;a href=&quot;https://www.flightglobal.com/news/articles/farnborough-aero-secrets-of-boeings-new-dreamliner-401784/&quot; rel=&quot;noreferrer&quot;&gt;hybrid laminar-flow control&lt;/a&gt; (HLFC).&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="-1" LastEditDate="2020-06-17T08:28:45.000" LastActivityDate="2018-06-08T22:02:44.223" CommentCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="29193" PostTypeId="2" ParentId="29181" CreationDate="2016-06-10T23:57:14.263" Score="8" Body="&lt;p&gt;This goes back a few years, but I was on a 727 departing LGA, and we had to abandon our position in the queue to taxi to the other end.  Everyone was all ready taking off with a tailwind but the aircraft weight and airline opspec would not permit us to launch.  We had to taxi to the other end but soon all the other planes joined us, because the wind was increasing over time.  Net result we took off sooner!  Happy dance! &lt;/p&gt;&#xA;" OwnerUserId="291" LastEditorUserId="291" LastEditDate="2018-11-07T16:53:08.703" LastActivityDate="2018-11-07T16:53:08.703" CommentCount="0" ContentLicense="CC BY-SA 4.0" />
  <row Id="29195" PostTypeId="2" ParentId="29176" CreationDate="2016-06-11T01:14:43.557" Score="5" Body="&lt;p&gt;There are five points that need to be addressed on the graph of range vs capacity, not just two.&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;Short and thin.  These routes are flown by small aircraft such as puddlejumpers and regional jets as well as smaller mainline aircraft, and represent the spokes in the classical hub-and-spoke model (Savannah-Atlanta or Bordeaux-Paris for instance).  Service frequencies are low to modest, and competition is generally fairly limited, with one or a few carriers on the route.&lt;/li&gt;&#xA;&lt;li&gt;Short and fat.  These routes mainly exist in areas where there are large cities close together, but land/sea connectivity has a tough time competing due to geographical or political issues.  Examples of this include Tokyo-Osaka and Taiwan-Hong Kong.  Oftentimes, service frequencies are high, competition is fierce, and both narrowbody and densely configured widebody (2-class seating at best) aircraft can be found.&lt;/li&gt;&#xA;&lt;li&gt;Long and fat.  These are your classical, long-haul hub-to-hub routes such as London-New York or Los Angeles-Sydney.  Most of these flights are on traditional 3-class or 4-class configured widebody aircraft, and see relatively infrequent service compared to shorter routes.&lt;/li&gt;&#xA;&lt;li&gt;Long and thin.  These routes are introduced to relieve congestion from major hubs, usually in international markets.  An example would be Newark-Glasgow, bypassing the otherwise-obligatory plane change at Heathrow or Amsterdam.  Other examples of this pattern include US domestic long-hauls.&lt;/li&gt;&#xA;&lt;li&gt;In the middle.  Most short-to-intermediate haul mainline flying is this way -- these may be busy hub-to-spoke connections, or inter-hub flights that aren't fat enough or long enough to sustain the use of larger aircraft.  LCC networks (Southwest, JetBlue, Ryanair, Easyjet) center around these types of routes because they work well for a homogenous fleet (vs. hub and spoke networks, which require smaller planes for the spokes and bigger planes for hub-to-hub).&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;" OwnerUserId="3825" LastActivityDate="2016-06-11T01:14:43.557" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29196" PostTypeId="2" ParentId="29176" CreationDate="2016-06-11T01:46:35.807" Score="1" Body="&lt;p&gt;In general as an aircraft gets bigger, with more passengers, the bigger the wing has to be to carry all of that extra load. As the wing gets longer, the root has to increase in thickness quite a bit due to the increased bending moment (also due to the increased load going into the wing). As the wingspan gets longer, the wing chord usually increases at the root as well (on commercial aircraft). Finally, since the wing root has has gotten thicker and longer, the center wing under the fuselage has also gotten taller and longer. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Considering the vast majority of fuel is stored in the wings and center wing on commercial aircraft (on many that is the only location of storage), and nearly all of the wing between the spars is dedicated to fuel storage, a higher capacity aircraft just has far more fuel storage volume available. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Of course you could put a huge wing on a small aircraft to give it a lot of range, but I think the other answers have done a good job of explaining why that isn't done. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-06-11T01:46:35.807" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29197" PostTypeId="2" ParentId="29169" CreationDate="2016-06-11T02:10:53.797" Score="1" Body="&lt;p&gt;In the FAA word, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5&quot; rel=&quot;nofollow&quot;&gt;14 CFR 121&lt;/a&gt; has a lot to say about flight attendant responsibilities. In fact the term flight attendant is used in Part 121 150 times. The most direct sections of Part 121 are &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1391&quot; rel=&quot;nofollow&quot;&gt;121.391 Flight attendants&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1392&quot; rel=&quot;nofollow&quot;&gt;121.392 Personnel identified as flight attendants&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1393&quot; rel=&quot;nofollow&quot;&gt;121.393 Crewmember requirements at stops where passengers remain on board&lt;/a&gt;, &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1394&quot; rel=&quot;nofollow&quot;&gt;121.394 Flight attendant requirements during passenger boarding and deplaning&lt;/a&gt; and &lt;a href=&quot;http://www.ecfr.gov/cgi-bin/text-idx?SID=47e3db32559d6354948f7080e1960aa4&amp;amp;mc=true&amp;amp;node=pt14.3.121&amp;amp;rgn=div5#se14.3.121_1397&quot; rel=&quot;nofollow&quot;&gt;121.397 Emergency and emergency evacuation duties&lt;/a&gt;.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;There are more sections dedicated to training and duty times as well, and various other responsibilities are sprinkled throughout Part 121. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Section 121.391 basically requires at least 1 flight attendant for each full or partial block of 50 seats. This is why when American Airlines went to a 160 seat configuration on their 737-800s they had to add a fourth FA. Later they removed ten seats so they could eliminate the extra FA. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastActivityDate="2016-06-11T02:10:53.797" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29198" PostTypeId="1" CreationDate="2016-06-11T02:35:44.647" Score="0" ViewCount="54" Body="&lt;p&gt;Typical taxi speeds are less than 20 knots. These are speeds at which city-transport  buses regularly operate &amp;amp; even exceed. Buses don't mandate seat belts &amp;amp; in fact even allow standees. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now my question is: Is the risk of collision higher in a taxing aircraft? Are decelerations higher? Or do we operate in aviation with a lower risk appetite. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Just curious. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As a counterexample, during flight even if the seatbelt light is turned on, toilet-visits seem allowed (mostly, unless its severe turbulence). On the other hand, the ground taxi period seems an absolute PAX movement prohibition period akin to takeoff &amp;amp; landing. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is ground-taxi riskier than in-flight seat-belts-on periods? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;PS. Don't interpret this as advocacy to get rid the seat-belts during-taxi rule. Just curious about the differential risk assessment. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;In any case most safety prohibitions are a risk-vs-convenience tradeoff. Just evaluating that tradeoff in this particular case. &lt;/p&gt;&#xA;" OwnerUserId="7611" LastActivityDate="2016-06-11T02:35:44.647" Title="Seatbelts-on during taxi protocol: Risk assessment" Tags="&lt;accidents&gt;&lt;taxiing&gt;" AnswerCount="0" CommentCount="5" ClosedDate="2016-06-11T04:58:38.820" ContentLicense="CC BY-SA 3.0" />
  <row Id="29200" PostTypeId="1" CreationDate="2016-06-11T04:58:47.477" Score="0" ViewCount="234" Body="&lt;p&gt;Could you please give me the steps or procedure to start the a/c twin otter gas turbine engine?&lt;/p&gt;&#xA;" OwnerUserId="15355" LastActivityDate="2016-06-11T04:58:47.477" Title="Twin otter engine starting procedure" Tags="&lt;turboprop&gt;" AnswerCount="0" CommentCount="4" ClosedDate="2016-06-11T09:41:15.770" ContentLicense="CC BY-SA 3.0" />
  <row Id="29204" PostTypeId="1" AcceptedAnswerId="30995" CreationDate="2016-06-11T11:10:25.067" Score="23" ViewCount="7043" Body="&lt;p&gt;I'd think that on certain heavily trafficked routes, especially ones with lots of business travelers, there would be a market for high-speed (supersonic) flights?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Why are there currently no supersonic commercial flights? (Or are there?)&lt;/p&gt;&#xA;" OwnerUserId="11795" LastEditorUserId="11795" LastEditDate="2016-08-25T21:19:38.273" LastActivityDate="2019-01-30T23:12:35.590" Title="Why are there no commercial supersonic flights at present?" Tags="&lt;commercial-aviation&gt;&lt;supersonic&gt;" AnswerCount="5" CommentCount="13" FavoriteCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29205" PostTypeId="1" AcceptedAnswerId="29206" CreationDate="2016-06-11T13:21:58.130" Score="3" ViewCount="610" Body="&lt;p&gt;When executing an instrument approach, when the pilot should start reference the RVR reported. Also, How do we get the required RVR for the current approach in execution and actual RVR. I think actual RVR can be part of METAR data. But I am not sure on the required RVR.&lt;/p&gt;&#xA;" OwnerUserId="15361" LastActivityDate="2016-06-13T14:00:35.237" Title="How do we get Required RVR or Actual RVR for an instrument approach?" Tags="&lt;approach&gt;" AnswerCount="1" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29206" PostTypeId="2" ParentId="29205" CreationDate="2016-06-11T13:32:13.580" Score="4" Body="&lt;p&gt;Current RVR is obtained from the METAR, yes, which in turn is obtained from &lt;a href=&quot;https://en.wikipedia.org/wiki/Runway_visual_range&quot; rel=&quot;nofollow noreferrer&quot;&gt;transmissometer(s)&lt;/a&gt; on the airport site.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Minimum allowable RVR is obtained from charts (&lt;a href=&quot;http://ww1.jeppesen.com/documents/aviation/business/ifr-paper-services/intro-USA.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;chart legend from Jeppesen, PDF&lt;/a&gt;), more specifically the &lt;a href=&quot;https://en.wikipedia.org/wiki/Approach_plate&quot; rel=&quot;nofollow noreferrer&quot;&gt;instrument approach plate&lt;/a&gt; for approaching an airport. And on the &lt;a href=&quot;https://en.wikipedia.org/wiki/Standard_instrument_departure_(SID)&quot; rel=&quot;nofollow noreferrer&quot;&gt;SID&lt;/a&gt; chart for departing.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Example:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/NFz31.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/NFz31.png&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;R is RVR in hundreds of feet, V is Visibility in miles, in this example. Units can change and will be denoted, check full PDF for all examples.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-06-13T14:00:35.237" LastActivityDate="2016-06-13T14:00:35.237" CommentCount="3" ContentLicense="CC BY-SA 3.0" />
  <row Id="29207" PostTypeId="1" AcceptedAnswerId="29208" CreationDate="2016-06-11T18:20:18.950" Score="11" ViewCount="2316" Body="&lt;p&gt;I know this is not practical (considering there is normally not much use to use up to 30 degrees of elevator trim), but if you were on a Boeing 777 or 737, or similar, and the elevator trim was set into said position, and stuck there, would it be possible to safely land said aircraft in that condition?&lt;/p&gt;&#xA;" OwnerUserId="15364" LastEditorUserId="1467" LastEditDate="2016-06-11T18:29:27.743" LastActivityDate="2018-06-05T09:27:05.377" Title="Is it possible to land a commercial aircraft with an elevator trim stuck at a high degree?" Tags="&lt;landing&gt;&lt;emergency&gt;&lt;trim&gt;" AnswerCount="2" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29208" PostTypeId="2" ParentId="29207" CreationDate="2016-06-11T18:31:23.223" Score="15" Body="&lt;p&gt;From the Boeing 737 emergency procedures:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;After all attempts fail to free the stabilizer...&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;ul&gt;&#xA;  &lt;li&gt;Anticipate higher than normal elevator forces during approach and landing.&lt;/li&gt;&#xA;  &lt;li&gt;The thrust reduction at flare will cause a nose down pitch.&lt;/li&gt;&#xA;  &lt;li&gt;Note: Elevator control is sufficient to safely land the airplane &lt;strong&gt;regardless of stabilizer position.&lt;/strong&gt;&lt;/li&gt;&#xA;  &lt;/ul&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;&lt;em&gt;Note on terminology:&lt;/em&gt; Most jet-liners (including the 777 and 737 as the question requests) use a &lt;a href=&quot;https://www.skybrary.aero/index.php/Trimmable_Horizontal_Stabiliser&quot; rel=&quot;nofollow noreferrer&quot;&gt;trimmable horizontal stabilizer&lt;/a&gt; (THS), in which the pitch trim is achieved by positioning the whole rear wing up/down -- as opposed to using trim tabs.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/hL4Pw.jpg&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/hL4Pw.jpg&quot; alt=&quot;enter image description here&quot;&gt;&lt;/a&gt;&lt;br&gt;&#xA;(&lt;a href=&quot;https://www.airteamimages.com/embraer-erj-190_ER-ECB_air-moldova_142006.html&quot; rel=&quot;nofollow noreferrer&quot;&gt;airteamimages.com&lt;/a&gt;) THS of an Embraer ERJ-190.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2018-06-05T09:27:05.377" LastActivityDate="2018-06-05T09:27:05.377" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="29209" PostTypeId="2" ParentId="29204" CreationDate="2016-06-11T18:52:30.283" Score="6" Body="&lt;p&gt;There are regulations in place that state that a supersonic aircraft can only go supersonic when over sea, (especially seen with concerns about noise levels when concorde was in production, and sonic booms 'breaking windows' when flying over land) and must be subsonic when on land, which limits the amount of destinations you could get supersonic flights to (like if you were travelling from Turkey to France), not to mention that supersonic jets guzzle fuel (especially delta winged design ones, such as Concorde and the TU-144, which need extra thrust on takeoff due to the design making it harder to gain lift).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They're very expensive to maintain as a whole, which can be seen by the amount of wear that can be done during supersonic flight, which is costly to repair, and if oil prices go up, it adds onto that expense because of how much it guzzles. If there's a demand for people to fly supersonic, then considering there's limited routes to do so, it would just make a supersonic jet a tin can of losses.&lt;/p&gt;&#xA;" OwnerUserId="15364" LastActivityDate="2016-06-11T18:52:30.283" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29210" PostTypeId="1" AcceptedAnswerId="30144" CreationDate="2016-06-11T21:09:22.953" Score="10" ViewCount="17235" Body="&lt;p&gt;Last year at &lt;a href=&quot;http://www.eaa.org/en/airventure&quot; rel=&quot;noreferrer&quot;&gt;EAA Airventure&lt;/a&gt; I saw a helicopter (can't remember the model, but it was something like a &lt;a href=&quot;https://en.wikipedia.org/wiki/Eurocopter_EC135&quot; rel=&quot;noreferrer&quot;&gt;Eurocopter EC135&lt;/a&gt; or similar with a full glass cockpit). It was US registered (N-Number tail) but had &quot;Experimental&quot; written on the door. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;When I asked the person at the booth why it was experimental they said it was because they used it as a test platform for new avionics packages, which got me thinking...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Is there a method to transition an aircraft from certified to experimental? Or is this done on a case-by-case basis through the FAA? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I can see advantages for an aircraft owner to want to transition to experimental if they want to keep up on latest (cheapest) non-TSO'd avionics and be able to do more work on the aircraft without an A&amp;amp;P. The downside is obviously higher insurance rates, but I'm not sure it would be a significant difference...&lt;/p&gt;&#xA;" OwnerUserId="12623" LastEditorUserId="12623" LastEditDate="2016-06-12T01:17:08.600" LastActivityDate="2019-06-12T18:19:58.270" Title="What is the procedure to turn a certified aircraft into an experimental aircraft?" Tags="&lt;faa&gt;&lt;aircraft-certification&gt;&lt;experimental-aircraft&gt;" AnswerCount="3" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29211" PostTypeId="1" AcceptedAnswerId="29220" CreationDate="2016-06-11T22:55:01.790" Score="8" ViewCount="2496" Body="&lt;p&gt;From &lt;a href=&quot;https://aviation.stackexchange.com/a/13810/128&quot;&gt;this question&lt;/a&gt;:&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;In airliners, shoulder harnesses are not installed for &lt;strong&gt;passengers&lt;/strong&gt; because:&lt;/p&gt;&#xA;  &#xA;  &lt;ol&gt;&#xA;  &lt;li&gt;it is not mandated by law&lt;/li&gt;&#xA;  &lt;li&gt;it is too much for average passengers to deal with&lt;/li&gt;&#xA;  &lt;li&gt;it requires money to install&lt;/li&gt;&#xA;  &lt;li&gt;it is superfluous in a crash when compared to the same safety from a lap belt&lt;/li&gt;&#xA;  &lt;/ol&gt;&#xA;  &#xA;  &lt;p&gt;&lt;strong&gt;Flight crew&lt;/strong&gt; is required to use the shoulder harness (when installed) as it is the law (&lt;a href=&quot;https://www.law.cornell.edu/cfr/text/14/91.105&quot; rel=&quot;nofollow noreferrer&quot;&gt;14 CFR 91.105&lt;/a&gt;): [...]&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;How is 4 true? Why would shoulder harnesses be obligated for flight attendants in their jump seats, but not for passengers? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Against 1 and 2, should shoulder harnesses be installed, at least to enable passengers to decide to use them or not? &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Against 3, do the safety benefits not outweigh the costs? &lt;/p&gt;&#xA;" OwnerUserId="128" LastEditorUserId="11215" LastEditDate="2017-12-29T20:15:56.947" LastActivityDate="2019-01-13T18:21:06.497" Title="Why are passengers not given the option of shoulder harnesses?" Tags="&lt;safety&gt;" AnswerCount="2" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29212" PostTypeId="2" ParentId="29204" CreationDate="2016-06-11T23:24:47.810" Score="22" Body="&lt;p&gt;There are numerous reasons. They are &lt;strong&gt;not&lt;/strong&gt; all economic ones by the way, even if most of them are.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;First, you must build your supersonic airliner&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Neither of the two supersonic airliners that once flew fly anymore, and none of the aircraft that still exist are likely to made airworthy ever again.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Someone's going to have to design and build a new one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Unfortunately...&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;The historical moment has passed&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;The British and French governments began collaborating in earnest on the project in the late 1950s. The immediate post-war period was over, but they both faced a kind of crisis as their colonial empires fell apart across the world, making for just the kind of mood in which weakening global powers reach for grand projects that will prove that they really are, after all, in the top club of nations.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;For slightly different reasons at the same time the USA and the USSR were also making huge efforts to prove themselves Top, expressed in the race to reach the moon.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It was at any rate a moment that seemed to demand extraordinary symbolic achievements in technology by certain governments.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Now, no government has the stomach for that kind of project, nor do their populations (one wonders whether China or India might soon decide that it's time for &lt;em&gt;their&lt;/em&gt; grand gesture though). International agreements, such as those that bind the member states of the European Union as well as trade agreements that reach across the world, limit the kind of support governments can provide to enterprises of this scale, that made them possible in the past.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;They don't seem to be able to keep their own airlines going any more, never mind global-scale technological extravagances.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So if the 21st century is no longer a time for such politically-powered technological extravagance, it's going to be up to private enterprise to produce it, and now the economic factors start to become more important.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;A supersonic airliner is less necessary than it was&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Time spent in the air is not &quot;dead time&quot; for the highly-expensive business traveller any more. Increasingly, in-flight Internet and telephone connections will make it less urgent to be there &lt;em&gt;now&lt;/em&gt;. The business traveller will be more interested in comfort and facilities, if the flight time can be used productively.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Fluctuating oil prices are on everyone's mind&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;A supersonic airliner will be fuel-expensive. Since the 1970s, the price of oil has fluctuated violently enough several times to cause various airline-related extinctions. Airlines flying supersonic airliners will take the first hit.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;And so is the environment&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Airlines already face a great deal of pressure because of environmental concerns: it's an industry that's hugely damaging to the planet. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;A supersonic airliner will be considerably more damaging than most. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;Which airline is likely to want to be the first to fly the most environmentally-noxious airliner in the world in order for the super-rich to spend a little less time getting wherever it is they go?&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;Possibly, no airline could afford to buy it&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;It's far from clear that any airline could afford to invest in a supersonic fleet, and it would have to earn a vast amount of money even if they could.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;It wouldn't be very useful&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;Where would it fly? One thing that the Concorde project failed to foresee was just how obnoxious the aircraft were to the people who lived anywhere near their noise. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;For a while the British and French put up with the appalling noise it made because it reassured them that they were still great, but after a while even they grew pretty tired of it. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Americans cared rather less about Franco-British greatness, and kept trying to ban it from the USA; it was banned from flying over various other places too.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Let's assume that you could build a supersonic airliner that was civilised enough to be reasonably welcome at airports near populous cities (and Concorde with its 1960s turbojets would not be), you'd still have an aircraft that could not be flown over populated land at supersonic speeds, because of the horrific noise its shockwave would make. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, it would be pretty much limited to coast-to-coast operations over oceans.&lt;/p&gt;&#xA;&#xA;&lt;h1&gt;In conclusion&lt;/h1&gt;&#xA;&#xA;&lt;p&gt;There's not just one reason why we haven't seen a new supersonic passenger airliner, but a whole raft of them - and I think it will be a very long time before we do.&lt;/p&gt;&#xA;" OwnerUserId="14197" LastActivityDate="2016-06-11T23:24:47.810" CommentCount="8" ContentLicense="CC BY-SA 3.0" />
  <row Id="29214" PostTypeId="2" ParentId="14569" CreationDate="2016-06-12T01:44:08.263" Score="5" Body="&lt;p&gt;I will use the 757 as an example, but everything is true for every multi-axle landing gear I've ever been around (except the 777).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The truck (bogie) is tilted into a specific angle so that it'll fit into the wheel well, all other functions are secondary. The truck must be angled because the landing gear strut itself is not completely perpendicular to the fuselage, due to other considerations. This is what the 757 Maintenance Manual says about the truck position actuator (aka tilt actuator): &quot;This actuator applies the force to put the truck assembly at an angle to permit clearance with the structure.&quot;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;This &lt;a href=&quot;https://www.youtube.com/watch?v=jwRl5GwUYN4&amp;amp;t=4m20s&quot; rel=&quot;nofollow noreferrer&quot;&gt;YouTube video&lt;/a&gt; shows the extension/retraction of the 757 landing gear, you can clearly see in the video that if the truck was not at a specific angle it would impact either the keel beam or the wing to body fairings. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The reason it stays tilted in the down position comes down to cost and complexity. The actuator is a simple one-way hydraulic actuator, meaning it can only be powered into the extended direction. Any time hydraulic power is supplied to the landing gear, either in the up or down position the truck positioning actuator is powered on the extended side, regardless of gear position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;&lt;em&gt;Extra information, for the non-TL:DR crowd&lt;/em&gt;&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;When the aircraft touches down, the actuator attempts to keep the truck tilted, which massively increases the pressure in the actuator (normal system pressure is 3000psi). A check valve prevents the hydraulic fluid from being forced back into the hydraulic supply system, then at 4500 psi dumps the fluid into the return allowing the actuator to collapse. At takeoff when the aircraft rotates it again forces this actuator even further into the retracted position as the aft wheels get closer to the fuselage. As you can see the stroke of this actuator must be quite long. So fully extended gives you a toe up position and fully retracted gives you a toe down position. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;To have the truck powered to any position other than fully extended would first require the ability to power in both directions, which adds a lot of complexity to the hydraulics system and actuator and this would only get you fully extended and fully retracted. To position the truck in any other position would require complex control valves with position feedback or multi-position actuators and also sequence valves to ensure any time the gear was not down and locked the truck was in the proper position. Since there is no need to flatten the truck for landing, this is not down.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Finally having the truck position always powered fully extended means the truck will always be in the correct position for retraction and you can use the truck tilt to detect air/ground (weight on wheels). In fact on the 757, if pressure to the truck positioning actuator fails, the aircraft will not switch to ground mode until the nose gear shows weight on wheels.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;To address the nose down moment that has been mentioned, while technically this does happen the moment is very small relative to the aircraft and is over in a fraction of a second. The actuator itself is fairly small, smaller than a spoiler actuator and reacts its load on the strut very near the truck pivot pin, so the moment arm is short. Also this same force would fight against aircraft rotation at takeoff. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;The 767 does nose down because its struts are at a different angle than the 757 and they have to be nose down to fit in the wheel well, this is a design decision due to a limitation at LGA. &lt;/p&gt;&#xA;" OwnerUserId="13366" LastEditorUserId="946" LastEditDate="2018-06-11T23:41:13.677" LastActivityDate="2018-06-11T23:41:13.677" CommentCount="11" ContentLicense="CC BY-SA 4.0" />
  <row Id="29215" PostTypeId="1" AcceptedAnswerId="29243" CreationDate="2016-06-12T01:56:59.233" Score="10" ViewCount="671" Body="&lt;p&gt;It's not uncommon for polar flights to lose GPS signal (ionosphere issues due to the high latitudes). But it is not a concern because the typical IRS drift is 650 meters for every hour of flight, and the skies are empty (compared to the &lt;a href=&quot;https://en.wikipedia.org/wiki/North_Atlantic_Tracks&quot; rel=&quot;noreferrer&quot;&gt;Atlantic tracks&lt;/a&gt;) in those regions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Sooner or later GPS will be back, navaids will be within reach, and radar coverage will resume.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Q: Now, what happens when the GPS signal is lost? Does the FMS navigation start to drift from this point on, or does it switch to all the accumulated IRS drifting that's been going on for hours prior?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;One way to picture the latter (I guess), is the &lt;em&gt;magenta&lt;/em&gt; line on the navigation display to abruptly shift away from the plane-symbol, even if it is just by a mere few nautical miles.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;My question applies to the older IRS systems that require stationary alignment, unlike the new GPS-coupled &lt;a href=&quot;http://www.skybrary.aero/index.php/Inertial_Navigation_System_(INS)#Alignment&quot; rel=&quot;noreferrer&quot;&gt;align-in-motion&lt;/a&gt; systems found on the 787, etc.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2017-02-14T21:21:01.470" LastActivityDate="2017-02-17T20:35:05.547" Title="How does an FMS shift after losing all external navaids?" Tags="&lt;navigation&gt;&lt;gnss&gt;&lt;oceanic&gt;&lt;fms&gt;&lt;inertial-nav-system&gt;" AnswerCount="1" CommentCount="5" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29217" PostTypeId="1" CreationDate="2016-06-12T05:00:24.467" Score="18" ViewCount="5154" Body="&lt;p&gt;I've noticed that (long-haul) airliners &lt;em&gt;sometimes&lt;/em&gt; travel at as high as 1000  km/h (I believe I've even seen 1040 km/h), but usually they fly closer to 800 km/h, for most of the trip.  This seems odd to me.  &lt;/p&gt;&#xA;&#xA;&lt;p&gt;I would understand this if it was due to wind speed; however, usually those that travel slowly seem to do so for most if not all of the journey, regardless of the direction of travel (e.g. even if they are going up to the north pole and back down, and whether the net direction is west or east). I find it nearly impossible to explain this using wind speed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Similarly, given that the speed of sound is around 1,060 km/h at 12 km above sea level, I find it equally uncompelling to reason that they need to go at less than mach 0.8 due to the speed of sound. I would understand it if they limited themselves to (say) mach 0.95 (obviously you don't want to do mach 0.99 due to variability etc.), but I &lt;em&gt;routinely&lt;/em&gt; see top speeds that are around mach 0.8 for cross-continental flights, and I don't understand why.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;So, what's the real reason?&lt;/p&gt;&#xA;" OwnerUserId="732" LastEditorUserId="1696" LastEditDate="2018-08-09T19:35:35.777" LastActivityDate="2020-10-17T17:46:41.637" Title="Why does the speed of commercial airliners fluctuate, sometimes as high as 1,060 km/h or as low as 800 km/h?" Tags="&lt;airliner&gt;&lt;airspeed&gt;&lt;jet&gt;&lt;groundspeed&gt;" AnswerCount="5" CommentCount="11" FavoriteCount="4" ContentLicense="CC BY-SA 4.0" />
  <row Id="29218" PostTypeId="2" ParentId="29217" CreationDate="2016-06-12T05:19:29.173" Score="22" Body="&lt;p&gt;Information displayed to passengers through the entertainment system often gives the aircraft &lt;a href=&quot;https://en.wikipedia.org/wiki/Ground_speed&quot; rel=&quot;noreferrer&quot;&gt;ground speed&lt;/a&gt; rather than airspeed.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Wind affects the ground speed, you're right about that.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Few things out of the way first.&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;Pilots do not use ground speed for flying, instead they use &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspeed#Indicated_airspeed&quot; rel=&quot;noreferrer&quot;&gt;indicated airspeed&lt;/a&gt;.&lt;/li&gt;&#xA;&lt;li&gt;Mach number is &lt;strong&gt;not&lt;/strong&gt; derived from the ground speed, as it is dependent on air temperature, instead it is derived from the &lt;a href=&quot;https://en.wikipedia.org/wiki/Airspeed#True_airspeed&quot; rel=&quot;noreferrer&quot;&gt;true airspeed&lt;/a&gt;. Notice we already have two kinds of airspeed. There are more still.&lt;/li&gt;&#xA;&lt;li&gt;Aircraft type (for example 737 vs. 777) determines &quot;top speed&quot;. Not all airliners are the same. Those two types range from Mach 0.77 to Mach 0.85, roughly.&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;In less words than Wikipedia which I linked:&lt;/p&gt;&#xA;&#xA;&lt;ol&gt;&#xA;&lt;li&gt;&lt;p&gt;Indicated airspeed tells the pilot the aerodynamically relevant speed to be used for flying.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;True airspeed is the actual speed relative to the surrounding atmosphere.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;From the true airspeed, add or subtract tail or headwind, and you get ground speed from that. Typical wind experienced by the regular subsonic airliner is fast (+100 km/h). The tail or headwind &lt;em&gt;component&lt;/em&gt; would vary depending on the plane's direction and the wind's direction.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Finally, Mach number is a function of temperature and &lt;strong&gt;true airspeed&lt;/strong&gt; (notice, not ground speed). The higher you are, the colder it is. Also very important, Mach number is a ratio, &lt;strong&gt;never a speed&lt;/strong&gt;. Since the speed of sound varies as the atmosphere changes density and temperature at the different altitudes.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ol&gt;&#xA;&#xA;&lt;p&gt;Here's a nice &lt;a href=&quot;http://www.telegraph.co.uk/news/worldnews/northamerica/usa/11337617/Jet-stream-blasts-BA-plane-across-Atlantic-in-record-time.html&quot; rel=&quot;noreferrer&quot;&gt;story&lt;/a&gt;, a 1200 km/h &lt;em&gt;subsonic&lt;/em&gt; flight.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Summary:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Pilots don't use ground speed (for flying), mach number is not a speed.&lt;/p&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2016-06-13T13:05:55.663" LastActivityDate="2016-06-13T13:05:55.663" CommentCount="6" ContentLicense="CC BY-SA 3.0" />
  <row Id="29219" PostTypeId="2" ParentId="29217" CreationDate="2016-06-12T05:37:58.943" Score="22" Body="&lt;p&gt;There are three different speeds that are of relevance here:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;p&gt;Groundspeed- This is probably the speed indicated to the passenger. For them, this is the most relevant as it determines the time taken for the trip&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Airspeed- This is the speed of relevance to the flight crew and is used for flight.&lt;/p&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;p&gt;Local airspeed- This determines the maximum speed of (subsonic) airliners. The reason is that the local airspeed over the wings are higher compared to the undisturbed flow- a result of the air being accelerated over the wing. As a result, the local airspeed over the wing can exceed Mach 1 quite a bit before the airspeed of the airliner goes anywhere near that. &lt;/p&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;&#xA;&lt;p&gt;The result of such local supersonic flow would be a rapid rise of drag at the &lt;a href=&quot;https://en.wikipedia.org/wiki/Drag_divergence_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;drag divergence Mach number&lt;/a&gt; (which is greater than the &lt;a href=&quot;https://en.wikipedia.org/wiki/Critical_Mach_number&quot; rel=&quot;noreferrer&quot;&gt;critical Mach number&lt;/a&gt;).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://i.stack.imgur.com/7NNO9.png&quot; rel=&quot;noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/7NNO9.png&quot; alt=&quot;Drag Divergencce&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Image taken from &lt;a href=&quot;https://www.google.co.in/url?sa=i&amp;amp;rct=j&amp;amp;q=&amp;amp;esrc=s&amp;amp;source=images&amp;amp;cd=&amp;amp;cad=rja&amp;amp;uact=8&amp;amp;ved=0ahUKEwjjjJaq4aHNAhVMpo8KHeG-BzIQjhwIAw&amp;amp;url=https%3A%2F%2Fwww3.nd.edu%2F~atassi%2FTeaching%2Fame%252060639%2FNotes%2Fcompressible.pdf&amp;amp;psig=AFQjCNGzylsDbHDVxWW_x_L4lj3GnW4dcQ&amp;amp;ust=1465794301621178&quot; rel=&quot;noreferrer&quot;&gt;notes of Advanced Aerodynamics&lt;/a&gt; by Professor H.M. Atassi of University of Notre Dame&lt;/p&gt;&#xA;&#xA;&lt;p&gt;In order to avoid the drag penalty, the airliners fly at speeds below the drag divergence Mach number. The reason is reduced speed is not the free-stream Mach number- it is the local Mach number, which should be kept below the Drag divergence Mach number.&lt;/p&gt;&#xA;" OwnerUserId="9731" LastActivityDate="2016-06-12T05:37:58.943" CommentCount="2" ContentLicense="CC BY-SA 3.0" />
  <row Id="29220" PostTypeId="2" ParentId="29211" CreationDate="2016-06-12T05:42:15.370" Score="8" Body="&lt;p&gt;I'll address these one by one.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Should shoulder harnesses be installed, at least to enable passengers to decide to use them or not?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;No. They would not serve a significant purpose to improve safety &lt;em&gt;in those seats&lt;/em&gt;, and they would add weight and increase maintenance costs for airlines.  Keep reading, and this will come to light collectively with my full answer.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Why would shoulder harnesses be obligated for flight attendants in their jump seats, but not for passengers?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Those seats aren't lined up in rows, therefore there is no seat in front of them that they would hit and be stopped by.  Think of it like a school bus with no seat belts; the passengers will be stopped by the seat in front of them in a &lt;strong&gt;low-force&lt;/strong&gt; crash, but the bus driver wears a seat belt because there is a steering wheel and windshield in front of them, not a padded seat.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;How is 4 true? (It is superfluous in a crash when compared to the same safety from a lap belt)&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Essentially, if there is a crash that will kill people, the shoulder harness will not be the thing that makes a difference.  The lap belt isn't really even there for crashes.  Extreme turbulence could throw someone up out of a seat; a lap belt is sufficient to prevent this.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;A shoulder strap is designed to reduce impact with an object on board a vehicle. A car, we can safely assume, will remain in one piece if it hits a concrete wall.  Airplanes do not have structures designed to withstand impacts like that. If a plane disintegrates in a crash, the passenger, packaged along with the lap belt, shoulder strap, and all, will come to impact the external object directly due to structural failure.  No seat belt can save you from a total structural failure.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Do the safety benefits not outweigh the costs?&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Since there really is no safety benefit whatsoever in adding them in the seats that don't already have them, no.  It would be security theater that costs airlines a lot of money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Regarding Pilots&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Notice I highlighted the low-force impact statement up above in regards to buses.  Let's say there is a low-force impact in a plane such as a taxiing crash that jars everyone on board. The passengers will hit the seats in front of them, not that the seats are even necessary to prevent injury.  However the pilots, on the other hand, have a lot of &lt;em&gt;hard&lt;/em&gt; instrumentation in front of them such as &lt;em&gt;throttle quadrants, and other things you don't want accidentally shoved forward&lt;/em&gt; during a ground crash.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;It appears that very little actual research has been done on this subject. For example, &lt;a href=&quot;http://etsc.eu/wp-content/uploads/1996_increasing_survival_rate_aircraft_accidents.pdf&quot; rel=&quot;nofollow noreferrer&quot;&gt;this European Transportation Safety Council report&lt;/a&gt; states,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;Many proposed safety measures &lt;strong&gt;require further research before their benefit to cabin&#xA;  safety and the optimal design can be firmly established&lt;/strong&gt;. In most cases, &lt;strong&gt;the availability&#xA;  of accurate, validated analytical models is indispensable.&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;It also states,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;It must be emphasised that these [death count] figures are at best estimates, since &lt;strong&gt;insufficient detailed&#xA;  accident information is available.&lt;/strong&gt;&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;and,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;A fundamental limitation to this process, however, is the &lt;strong&gt;lack of adequate accident&#xA;  information for a sufficient number of accidents to allow full cost benefit analyses&lt;/strong&gt; to be&#xA;  performed. &lt;strong&gt;The absence in many accident investigations of detailed information on&#xA;  injury mechanisms and cause of death makes the precise estimation of the potential&#xA;  benefits of any one measure very difficult.&lt;/strong&gt;&#xA;  The Cherry study (1995)*&#xA;  , one of few studies which have performed a detailed trade-off&#xA;  concerning the full range of possible survivability measures, provides insight into&#xA;  available options. However, the small number of accidents available for investigation&#xA;  in such studies means that &lt;strong&gt;the basis for determining priorities still relies heavily upon&#xA;  best expert judgement rather than a truly numerically-specific approach.&lt;/strong&gt; &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;...and lastly,&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;&lt;strong&gt;Three-point lap and shoulder harnesses:&lt;/strong&gt;&#xA;  As mentioned above, passengers who are restrained by a lap belt only and who do not&#xA;  take up a brace position prior to impact, are &lt;strong&gt;&lt;em&gt;likely to&lt;/em&gt;&lt;/strong&gt; suffer serious injuries due to the&#xA;  flailing motion of the upper body. As with rearward facing seats, the provision of&#xA;  three-point shoulder harness restraint systems would prevent this situation. If all&#xA;  passenger assumed the brace position prior to impact, the additional benefits of a threepoint&#xA;  shoulder harness would be small. In reality, however, for a variety of reasons,&#xA;  occupants generally do not assume a proper brace position, so a three-point lap and&#xA;  shoulder harness &lt;strong&gt;would be &lt;em&gt;likely&lt;/em&gt; [to] improve&lt;/strong&gt; occupant protection substantially. &lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;So, after reading this document, I did not find any numerical evidence contained within to support its claims, and it even states that it has very little research to go on and appears to be written in an almost purely speculative and subjective manner, which leads me back to the original point above...&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;a href=&quot;https://youtu.be/2KcRNi1HGGI?t=46&quot; rel=&quot;nofollow noreferrer&quot;&gt;A shoulder strap will not save you from a structural failure&lt;/a&gt;, and if the plane bumps into something while rolling wheels-down on the ground, the seat in front of the passenger will absorb their impact.&lt;/p&gt;&#xA;" OwnerUserId="14661" LastEditorUserId="14661" LastEditDate="2019-01-13T18:21:06.497" LastActivityDate="2019-01-13T18:21:06.497" CommentCount="8" ContentLicense="CC BY-SA 4.0" />
  <row Id="29221" PostTypeId="2" ParentId="29217" CreationDate="2016-06-12T07:35:36.190" Score="8" Body="&lt;p&gt;It is all about the wind. If you check schedules, you'll see that for example USA-Europe flights are way shorter (about an hour, say) than Europe -USA. This is due to the jetstream. I found it even more significant in the Southern hemisphere, when flying Australia-New Zealand (and back) or Santiago-Buenos Aires. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;As mentioned in the other answers, no commercial jet goes anywhere near mach 1. The &lt;em&gt;ground speed&lt;/em&gt; you are shown may be close to the speed of sound (it could even be higher, if the wind were strong enough), but the actual &lt;em&gt;airspeed&lt;/em&gt; of the aircraft (its speed relative to the air mass) is way less than that (around mach 0.8 for the bigger jets, and less for many smaller comercial aircraft). &lt;/p&gt;&#xA;" OwnerUserId="690" LastEditorUserId="690" LastEditDate="2016-06-12T14:11:30.967" LastActivityDate="2016-06-12T14:11:30.967" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29222" PostTypeId="2" ParentId="29217" CreationDate="2016-06-12T09:45:52.620" Score="4" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Similarly, given that the speed of sound is around 1,060 km/h at 12 km above sea level, I find it equally uncompelling to reason that they need to go at less than mach 0.8 due to the speed of sound. I would understand it if they limited themselves to (say) mach 0.95 (obviously you don't want to do mach 0.99 due to variability etc.), but I routinely see top speeds that are around mach 0.8 for cross-continental flights, and I don't understand why.&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;What matters is the speed of the air passing the plane. As the other answers have explained, the numbers you see in the cabin are typically speed over the ground, rather than speed through the air, so a big component of the difference is whether the plane has a headwind or a tailwind, which can easily add or subtract 100km/h at cruise altitude.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The other thing you need to look at is not just the plane's speed through the air but the speed of the airflow over the plane.  How are those things different? The point is that, as a plane pushes through a mass of air, air has to move out of the way of the big metal thing. This means that the air passing over the plane will be moving quite a bit faster than the plane's speed relative to the air. Thus, even a plane moving quite a bit below Mach&amp;nbsp;1 can have supersonic air flowing over it. The reason you don't fly at Mach&amp;nbsp;0.99 is not because a gust of headwind might take you over the speed of sound, but because you'd already be experiencing supersonic airflow  100% of the time, at that speed.&lt;/p&gt;&#xA;" OwnerUserId="946" LastActivityDate="2016-06-12T09:45:52.620" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29223" PostTypeId="1" CreationDate="2016-06-12T09:48:14.173" Score="3" ViewCount="284" Body="&lt;p&gt;Why wasn't MH17 prevented by government regulators from flying the route it took?&lt;/p&gt;&#xA;&#xA;&lt;p&gt;MH17 wasn't the first case of governments or combatants downing commercial aircraft: &lt;a href=&quot;https://en.wikipedia.org/wiki/Iran_Air_Flight_655&quot; rel=&quot;nofollow&quot;&gt;Iran Air Flight 655&lt;/a&gt; and &lt;a href=&quot;https://en.wikipedia.org/wiki/Korean_Air_Lines_Flight_007&quot; rel=&quot;nofollow&quot;&gt;Korean Air Lines Flight 007&lt;/a&gt; come to mind.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;I find it hard to believe that if an area had an unacceptably high risk for aircraft, that it would be up to the individual airlines to decide not to fly that route, rather than governments being flown over, or the source or destination countries, flat-out forbidding it unless there's no alternative.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Was military aircraft (such as &lt;a href=&quot;https://en.wikipedia.org/wiki/Ukrainian_Air_Force_Ilyushin_Il-76_shoot-down&quot; rel=&quot;nofollow&quot;&gt;Ukrainian Air Force Ilyushin Il-76&lt;/a&gt; and other incidents mentioned in the &lt;a href=&quot;https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_17#Background&quot; rel=&quot;nofollow&quot;&gt;Background&lt;/a&gt; section of Wikipedia's article on MH17) being shot down in the area a new phenomenon, with regulators not acting fast enough to deal with this new information?&lt;/p&gt;&#xA;" OwnerUserId="2250" LastEditorUserId="2250" LastEditDate="2016-07-09T12:30:32.910" LastActivityDate="2016-07-09T12:30:32.910" Title="Why didn't government regulators prevent MH17 from flying the route it took?" Tags="&lt;accidents&gt;&lt;mh17-accident&gt;" AnswerCount="1" CommentCount="3" ClosedDate="2016-06-12T16:19:36.040" ContentLicense="CC BY-SA 3.0" />
  <row Id="29224" PostTypeId="5" CreationDate="2016-06-12T09:49:22.837" Score="0" Body="&lt;p&gt;MH-17 was a Boeing 777 airliner owned my Malaysia Airlines which was shot down over Ukraine in July 2014. More information can be found &lt;a href=&quot;http://%20https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_17&quot; rel=&quot;nofollow&quot;&gt;here&lt;/a&gt;.&lt;/p&gt;&#xA;" OwnerUserId="-1" LastEditorUserId="12220" LastEditDate="2016-06-12T12:02:59.243" LastActivityDate="2016-06-12T12:02:59.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29225" PostTypeId="4" CreationDate="2016-06-12T09:49:22.837" Score="0" Body="Malaysia Airlines Flight 17, a flight shot down in Ukraine." OwnerUserId="2250" LastEditorUserId="12220" LastEditDate="2016-06-12T12:02:59.243" LastActivityDate="2016-06-12T12:02:59.243" CommentCount="0" ContentLicense="CC BY-SA 3.0" />
  <row Id="29227" PostTypeId="1" CreationDate="2016-06-12T10:21:42.220" Score="10" ViewCount="2456" Body="&lt;p&gt;Auxiliary Power Unit (APU) generators seem to be rated in kilo-volts-amperes (kVA) and not kilo-watts (kW). Are kVA not the same as kW? Is there a reason why the generator is rated in terms of kVA instead of kW?&lt;/p&gt;&#xA;" OwnerUserId="15347" LastEditorUserId="3201" LastEditDate="2016-06-12T20:44:31.090" LastActivityDate="2019-06-29T15:30:02.847" Title="Why are APU engine generators rated in kVA and not kW?" Tags="&lt;aircraft-design&gt;&lt;aircraft-performance&gt;" AnswerCount="2" CommentCount="7" ContentLicense="CC BY-SA 3.0" />
  <row Id="29228" PostTypeId="2" ParentId="29223" CreationDate="2016-06-12T12:11:29.190" Score="4" Body="&lt;p&gt;The Airlines can decide for them selves which route to take, however the government has an intelligence operation which can predict events that might happen in political unstable regions of the world. However in the case of MH17 it was not the &quot;army&quot; that shot down a plane but an conflict between rebels and the government.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;&lt;strong&gt;Routes flown to Kuala Lumpur&lt;/strong&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;While the flight from Amsterdam to Kuala Lumpur from Malaysia airlines have been suspended, one can still retrieve the route flown via flightaware.com:&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The KLM flightpath (KL809) 10246km:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/BzM3g.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/BzM3g.png&quot; alt=&quot;KLM flight 809 AMS-KUL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The Malaysia Airlines flightpath (MH19) 10855km:&#xA;&lt;a href=&quot;https://i.stack.imgur.com/4GYfr.png&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;img src=&quot;https://i.stack.imgur.com/4GYfr.png&quot; alt=&quot;Malaysia Airlines flight 19 AMS-KUL&quot;&gt;&lt;/a&gt;&lt;/p&gt;&#xA;&#xA;&lt;p&gt;From the plots it can be seen that both Airlines diverted their routes after the accident with MH17. They both avoid Ukrainian airspace.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Would flying these routes prevented the accident? Yes, but at the time intelligence agencies where not aware that the Separatists had acces to such advanced surface-to-air missiles. This also because the nature of the conflict would not suggest that such weapons would be required. &lt;/p&gt;&#xA;" OwnerUserId="15202" LastEditorUserId="15202" LastEditDate="2016-06-13T12:42:51.897" LastActivityDate="2016-06-13T12:42:51.897" CommentCount="4" ContentLicense="CC BY-SA 3.0" />
  <row Id="29231" PostTypeId="2" ParentId="29217" CreationDate="2016-06-12T15:50:05.650" Score="2" Body="&lt;p&gt;There are other factors that people already mentioned. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;On modern jets the flight computer can be programmed for efficiency during the route. &lt;/p&gt;&#xA;&#xA;&lt;p&gt;One of the reasons why mach 0.6-0.8 is used is it is sufficiently fast without burning a lot more fuel. The 777 if I remember correctly uses about 30% more fuel fully loaded to accelerate to 0.87 (edited) mach than at 0.7 mach at around 11.5 km. That's a lot of fuel to save yourself less than 20% of time. That extra fuel would result in more expensive tickets, in an industry which is trying to keep ticket prices to the minimum to compete. &lt;/p&gt;&#xA;" OwnerUserId="15373" LastEditorUserId="22726" LastEditDate="2019-05-20T02:00:37.193" LastActivityDate="2019-05-20T02:00:37.193" CommentCount="1" ContentLicense="CC BY-SA 4.0" />
  <row Id="29232" PostTypeId="1" CreationDate="2016-06-12T18:18:11.277" Score="13" ViewCount="16199" Body="&lt;p&gt;Presumably planes aren't completely empty of fuel when the land, so they don't start refueling from zero, is that right? Is it true that they must dump excess fuel before they land? How much? Presumably not all, in case there's a problem with the landing and they need to abort?&lt;/p&gt;&#xA;" OwnerUserId="15370" LastEditorUserId="1467" LastEditDate="2016-06-12T19:30:02.580" LastActivityDate="2017-07-31T16:36:40.270" Title="Do airplanes dump fuel before landing?" Tags="&lt;landing&gt;&lt;fuel&gt;" AnswerCount="6" CommentCount="6" FavoriteCount="1" ContentLicense="CC BY-SA 3.0" />
  <row Id="29233" PostTypeId="2" ParentId="29232" CreationDate="2016-06-12T18:51:11.083" Score="32" Body="&lt;blockquote&gt;&#xA;  &lt;p&gt;Is it true that they must dump excess fuel before they land?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Nope. You don't siphon your car just before your destination. Fuel is money.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Except in emergency in big planes, fuel then is a potentially lethal burden (weight).&lt;/p&gt;&#xA;&#xA;&lt;blockquote&gt;&#xA;  &lt;p&gt;... in case there's a problem with the landing and they need to abort?&lt;/p&gt;&#xA;&lt;/blockquote&gt;&#xA;&#xA;&lt;p&gt;Contingency fuel just for aborted landings, weather deviations, etc., is added during the fuel loading for such things. You get to keep it at the destination.&lt;/p&gt;&#xA;&#xA;&lt;hr&gt;&#xA;&#xA;&lt;p&gt;Further reading:&lt;/p&gt;&#xA;&#xA;&lt;ul&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/2854/14897&quot;&gt;When are aircraft required to dump fuel for emergency landings?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://aviation.stackexchange.com/q/33252/14897&quot;&gt;Can a wide body airliner land safely with a full fuel tank?&lt;/a&gt;&lt;/li&gt;&#xA;&lt;li&gt;&lt;a href=&quot;https://en.wikipedia.org/wiki/Flight_planning#Fuel_calculation&quot; rel=&quot;nofollow noreferrer&quot;&gt;Fuel planning—fuel calculation&lt;/a&gt;&lt;/li&gt;&#xA;&lt;/ul&gt;&#xA;" OwnerUserId="14897" LastEditorUserId="14897" LastEditDate="2017-07-30T16:17:40.927" LastActivityDate="2017-07-30T16:17:40.927" CommentCount="12" ContentLicense="CC BY-SA 3.0" />
  <row Id="29234" PostTypeId="2" ParentId="29227" CreationDate="2016-06-12T19:18:37.113" Score="19" Body="&lt;p&gt;Current and voltage don't always vary at the same time, one usually lags, this lag is the root of evils found in electrical engineering.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Any device is a mix of resistive load (no lag), inductive load (current lags) and capacitive load (voltage lags).&lt;/p&gt;&#xA;&#xA;&lt;p&gt;The lag (&lt;em&gt;phase shift angle&lt;/em&gt;) is denoted with Greek letter φ, and usually expressed as &lt;a href=&quot;https://en.wikipedia.org/wiki/Power_factor&quot; rel=&quot;nofollow noreferrer&quot;&gt;&lt;em&gt;cos φ&lt;/em&gt;, or &lt;em&gt;power factor&lt;/em&gt;&lt;/a&gt;. Power factor &lt;span class=&quot;math-container&quot;&gt;$=100 \cos φ$&lt;/span&gt;. Each device has its own individual φ, which may vary with conditions.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;Lag effect is only visible when voltage or current changes. This happens transiently in DC when the circuit is closed or opened (effect used to create high DC voltage from low DC voltage in a contact breaker), but constantly in AC  (not mentioning other induced variations, e.g. changes in mechanical demand on an electric engine will change the impedance of the coil, so the current). The effect of the phase angle increases with circuit frequency, and is significant in aircraft circuitry, with major loads working at 400 Hz.&lt;/p&gt;&#xA;&#xA;&lt;p&gt;